British
and Irish Legal Information Institute
Freely Available British and Irish Public Legal Information
[Home] [Databases] [World Law] [Multidatabase Search] [Help] [Feedback]
England and Wales High Court (Patents Court) Decisions
You are here: BAILII >> Databases >> England and Wales High Court (Patents Court) Decisions >> Rohm & Haas Company v. Collag Ltd [2000] EWHC Patents 72 (28th July, 2000)
URL: http://www.bailii.org/ew/cases/EWHC/Patents/2000/72.html
Cite as: [2000] EWHC Patents 72
[New search] [Help]
Rohm & Haas Company v. Collag Ltd [2000] EWHC Patents 72 (28th July, 2000)
HC
1999 01919
IN THE HIGH COURT
OF JUSTICE
CHANCERY DIVISION
PATENTS COURT
BEFORE: MR JUSTICE NEUBERGER
BETWEEN:
|
ROHM
& HAAS COMPANY
|
Claimant |
|
|
-and-
|
||
|
COLLAG
LIMITED
|
Defendant
|
Mr. Henry Carr QC and Dr. Piers Ackland (instructed by Messrs.
Hammond Suddards) appeared on behalf of the claimant.
Mr. Christopher Floyd QC and Mr. James St. Ville (instructed by Messrs. Bristows)
appeared on behalf of the defendant.
This is an approved judgment of the court and I direct that no further note or transcript be made.
The Hon
Mr Justice Neuberger
Dated: 28th July 2000
MR. JUSTICE NEUBERGER:
INTRODUCTION
- The claimant, Rohm & Haas Company, is the registered proprietor of European Patent EP 0 484 147 B1 ("the patent in suit") filed on 30th October 1991, granted on 26th August 1998. Its brief description is "propanil dispersible granule formulation". It teaches a process for manufacturing water-dispersible granules containing propanil, which is a herbicide used in agriculture. It claims a priority date of 31st October 1990.
- The defendant, Collag Ltd, has employed two different processes for manufacturing herbicide granules. For convenience, these processes have been referred to as "Process A" and "Process B". The present proceedings were initiated by the claimant, whose claim alleges that Process A infringes the patent in suit. In its defence, the defendant not only denies that Process A infringes, but it also counterclaims for revocation of the patent in suit, and for a declaration that Process B does not infringe. In relation to both Process A and Process B, the defendant denies infringement on the grounds that neither process involves the formation of a paste prior to extrusion. In relation to Process B only, the defendant raises an additional ground for justifying non-infringement of the patent in suit.
- With a view to being able to manufacture propanil granules by Process B and to market the resultant product, without having to wait for a determination as to the validity of the patent in suit or as to whether the fact that both processes involve the formation of a paste prior to extrusion renders them non-infringing, the defendant applied for the determination of a preliminary point. That application came before Laddie J on 24th February 2000, and, over the objection of the claimant, he ordered the following issues to be tried:
- These preliminary issues now comes before me for determination.
- Depending on factors such as the physical and chemical properties of the active ingredient, the method of application and the mode of action, agrochemicals are manufactured in a number of different formulations. Thus, some are supplied in liquid form, such as solutions, emulsions or suspensions, and others in solid form, such as powders or granules.
- A problem in the field of solid agrochemicals has been how to manufacture formulations which are not only convenient and safe, but which also contain a high concentration of active ingredient which will efficiently disperse in water before being sprayed onto crops. Where that ingredient is milled into very fine particles, normally in order to ensure efficient dispersion, this can create a number of problems. In the case of powders, the product can be difficult to handle, and can also be liable to "pack" during carriage, which can lead to inconsistent dosing levels. In the case of granules, the product can often be difficult to disperse in water.
- As at 31st October 1990, water dispersible granules containing agrochemicals were well known; they were made by mixing the ingredients in powder form and then granulating. Mixing could be effected by blending and/or milling, for instance, by an air mill using jets of air to break up particles to a smaller size. Granulating could also be effected by a number of techniques, one of which was extrusion granulation, which involves making a wet paste from powdered ingredients and forcing it through an extrusion machine, followed by drying.
- An essential ingredient of such water-dispersible granules was a surfactant (a shortening of the expression Surface Active Agent). Surfactants were known to act as wetting agents and as dispersing agents. A wetting agent, when added to liquid, increases the spreading or penetrating power of the liquid by reducing interfacial tension between the liquid and the surface on which it spreads. A dispersing agent adsorbs on to the surface of particles in a liquid medium, and helps to prevent their reaggregation.
- To act as a wetting agent, at least in water, a substance must be amphiphilic in nature. A substance is amphiphilic if it consists of molecules having both hydrophilic (water loving) and hydrophobic (water hating) ends. Such molecules orientate themselves at a surface and effectively reduce surface tension.
- A number of other ingredients were frequently included in water dispersible granules. Anti-foaming agents were, as their name suggests, added to prevent excess foaming. These were often themselves surfactants. Flow aids, milling aids, fillers and carriers such as clays, silica particles or starch were often included in the process to stop the particles sticking together, to soak up the moisture, to assist the flow, and to adjust the composition. Disintegrants, such as starch, sugar or inorganic salts were also used to break up the granules on the addition of water.
- As mentioned above, propanil is a herbicide, i.e. a weedkiller. Its chemical name is N-(3, 4-dichlorophenyl) propionamide. It is solid at room temperature, but melts at around 92ºC. Accordingly, any processing of propanil involving heat or pressure can run in to the risk of the particles becoming sticky; if that happens, they tend to agglomerate.
- Having explained that the claimed invention "relates to a process for preparing dispersible propanil granules", and having described two earlier patents, the specification continues at page 2, lines 14-23:
- After referring to propanil, there is this at page 2, lines 27-30:
- Immediately afterwards, at page 2 lines 31-35 the specification continues:
- At lines 36-41 of page 2, the specification continues:
- At page 2 lines 45-48 there is this:
- The invention is then summarised in precisely the same words as are to be found in Claim 1, which I will set out below.
- On page 3, the specification contains a number a statements and definitions upon which either or both of the parties rely. Thus, the expression "granular form" is described as meaning "granules substantially or which have a mean particle size of at least 1mm ...". At page 3 lines 10-11 one finds this:
- At lines 18-20 of page 3, the specification explains how to measure dispersability, and at lines 21-22 the term "attrition" is explained. At page 3, lines 25-28, there is this:
- At page 3 lines 42-43, the specification continues:
- At page 3, line 50, the specification contains this:
- At page 3, lines 53-57 one finds the following:
- On page 4 of the specification, there is this at lines 3-8:
- The final part of the specification to which I should refer is at page 4, lines 12 and 13:
- Page 5 of the specification contains a table setting out certain proprietary dispersants, wetting agents, flow aids and defoaming agents. There then follow a six pages of "Examples" and experiments. On pages 12-13 of the patent in suit, there are the Claims. Claim 1, which as I have mentioned, is effectively reproduced in the specification, is in these terms:
- It is necessary, for the purpose of dealing with the arguments raised in these proceedings, also to set out Claims 4, 5 and 10:
- Arising out of Laddie J's order, there are two substantive disputes between the parties. The first dispute concerns the meaning "surfactant" as that expression is used in the patent in suit, and in particular the meaning of the expression "one or more surfactants" in claim 1(a). The defendant contends that the expression is limited to amphiphiles, that it is limited to substances which perform their function in relation to two media, at least one of which is liquid. The claimant, on the other hand, argues that the expression "surfactant" can and, in the context of the patent in suit, does include non-amphiphiles and that it extends to any substance which is active at the interface of two phases to modify the surface energy of the substrate.
- Whoever succeeds on the first issue, it is still necessary to consider the second issue, namely whether Process B infringes the patent in suit. It is true that if the defendant succeeds on the first issue, Process B does not, at any rate at first sight, infringe the patent in suit, because it does not involve the addition of a surfactant (on the defendant's definition) at the stage identified in paragraph (a) of Claim 1. However, the issue of infringement still nonetheless arises. Equally, if the claimant succeeds on the first issue, the defendant still contends that Process B does not infringe, and the second issue falls to be resolved.
- There is another issue between the parties, namely as to which of them has the burden of proof. I shall deal with that issue first, and I will then turn to the substantive issues which divide the parties.
- The claimant's case is simple. The preliminary issues ordered by Laddie J, and which I am determining, both arise out of the defendant's counterclaim which seeks a declaration that, irrespective of the validity of the patent in suit and irrespective of the question of whether Process A infringes or not, Process B does not infringe. Accordingly, runs the claimant's argument, given that it is the defendant who is seeking that relief, the burden of proof lies on the defendant.
- In the absence of special circumstances, which, he contends, exist in the present case, Mr Christopher Floyd QC (who appears with Mr James St Ville for the defendant) accepts that the claimant's argument would be correct. In other words, where a person (whether claimant or defendant) seeks a declaration that a particular process or product does not infringe a patent, the onus lies on him to establish that he is entitled to the relief he seeks, even though it is in effect a negative declaration, rather than on the patentee. The correctness of this concession seems to me to be supported by what was said by Scarman LJ in Mallory Metallurgical Products Limited -v- Black Sivalls & Brison Incorporated [1977] RPC 321. In that case, the plaintiff was seeking a declaration of non-infringement under Section 66 of the Patents Act 1949, and, at 345 lines 28-30, one finds this:
- In the present case, the claimant, in its original pleading, contended that the defendant's product, which was in fact manufactured sometimes by Process A and sometimes by Process B, infringed the patent in suit. However, at that time, Mr Henry Carr QC (who appears with Mr Piers Acland for the claimant) says, and I accept, that the claimant was unaware that the defendant employed two different processes for manufacturing its product. It was only on 9th December 1999, that the defendant alleged for the first time that it had been using two different processes. Shortly thereafter, the defendant asked for acknowledgement from the claimant that Process B did not infringe, and the claimant refused to grant it. It was for this reason that the defendant counterclaimed for a declaration of non-infringement in relation to Process B.
- It seems to me that the thrust of the pleadings and correspondence is as follows. The claimant did not distinguish between Process A and Process B in its allegation of infringement against the defendant, because it was unaware that the defendant employed more than one process to manufacture its product. Once the defendant made it clear to the claimant that there were two separate processes, the parties proceeded on the basis that the claimant would be contending that Process A infringed, and was prepared to leave it to the defendant to decide whether to seek a declaration that Process B did not infringe. The defendant decided that it did wish to ask for such a declaration, and accordingly it counterclaimed appropriately. It is pursuant to that counterclaim that the preliminary issues ordered by Laddie J arose.
- From this, and from the terms of the correspondence (which I do not propose to discuss in any detail, not least because to do so would add unnecessarily to what is to be an over-long judgment) I extract the following two conclusions. First, it is solely the defendant's counterclaim for a declaration of non-infringement from which the instant preliminary issues are derived. Secondly, the claimant has been playing the system, in that, having first brought these proceedings, in relation to the defendant's product and its Process A, it is now leaving it to the defendant to decide whether to seek a declaration of non-infringement as to Process B.
- In the absence of the second conclusion, it seems to me that it would follow that the burden of proof is on the defendant, in light of Mr Floyd's concession, which is probably inevitable following Mallory (on the basis that the principle is no different under the current Patents Act). Although the claimant's attitude to Process B in these proceedings might be thought, according to taste, to be unattractive, tactical, canny or commercial, it is certainly not an abuse of the process of the court. Indeed, the very existence of the present preliminary issue shows that it cannot even be said that Process A and Process B have to be considered together. In those circumstances, if the worst that can be said about the claimant is that it is playing the system, I do not see that as a valid reason for a different result as to where the burden of proof lies in the absence of the claimant being open to such a charge.
- It is true that the claimant has not amended its original formal allegation of infringement against the defendant, which can therefore be fairly said to extend to Process B. However, it seems to me that, on a fair reading of the correspondence, the claimant made it clear to the defendant that, as soon as the claimant was told that the defendant had two processes, it was only Process A which was said to infringe. That the defendant accepted this is supported by the very existence and terms of its counterclaim, which only refers to Process B.
- In these circumstances,
I am of the view that the burden of proof in relation to the preliminary issues,
which I have to consider, lies on the defendant.
- The first issue (and indeed, arguably, the second issue) between the parties is ultimately one of pure construction for the court. In many, indeed most, cases of construction of a patent, expert evidence is not admissible - see for instance Lubrizol Corporation -v- Esso Petroleum Co. Ltd [1998] RPC 727 where the point is summarised in the headnote at 730, paragraph (4). However, in the present case, each party has called two expert witnesses. The reason is that the word "surfactant" has a technical meaning, and therefore expert evidence is admissible. The claimant called Michael Hounslow, Professor of Chemical Engineering, and Head of the Particle Products Group at the Department of Chemical and Process Engineering, at the University of Sheffield, and Anthony Ryan, Professor of Physical Chemistry, and Head of the Department of Chemistry, at the University of Sheffield. The defendant called Paul Luckham, Professor in the Department of Chemical Engineering and Chemical Technology at the Imperial College of Science, Technology and Medicine, London, and Mr Alan Knowles, who is, and has been since 1992, principal of his own consultancy offering advice and training in the area of environmentally friendly pesticide formulations, having previously worked for 22 years in the agrochemical division of ICI.
- The correct approach to construction of patents has been laid down in a number of cases, including two recent decisions of the Court of Appeal, Hoechst Celanese Corporation -v- BP Chemicals Ltd [1999] FSR 319 and Cartonneries de Thulin SA -v- CTP White Knight Ltd (unreported, 25th May 2000). In the former case, Hoechst [1999] FSR 319, the headnote, at holding (2) on page 320, summarises the correct approach as being:
- In the latter case, Cartonneries (unreported), the Court of Appeal, through Robert Walker LJ, referred to "an inadmissible attempt to use other parts of the specification to put a gloss on the clear language of the claim" (page 12) and considered, at page 37, that the right approach was to consider "the ordinary meaning of the words used in [a] claim" and then consider whether there was anything to "indicate a narrower [or indeed a different] construction". As was said by Mr. Carr, the cases show that the court must avoid the extremes of the strict literal construction on the one hand, and, on the other hand, an approach to the claims which treat them merely as a guideline. The court must strive to adopt an approach which leads to fair protection for the patentee and reasonable certainty for the public - see e.g. per Hoffmann J in Improver Corporation -v- Remington Consumer Products Ltd [1990] FSR 181 at 189-190 referring to Article 69 of the European Patents Convention.
- If the defendant wins on the first issue, the second issue will involve considering whether, given that the defendant's Process B involves a literal departure from the process claimed in the patent in suit, that departure is sufficient to prevent Process B infringing the patent in suit. In this connection, the proper approach is that laid down by Hoffmann J in Improver, applying the reasoning in the speech of Lord Diplock in Catnic Components Limited -v- Hill & Smith Limited [1982] RPC 183 at 243. In Improver [1990] FRS 181 at 189, Hoffmann J said that, where "a feature embodied in an alleged infringement... fell outside the primary, literal or acontextual meaning of a descriptive word or phrase in the claim ("a variant")" then "the court should ask itself the following three questions", and those questions ("the Improver questions") were:
- It is convenient to consider at this juncture the person to whom the patent in suit should be treated as addressed. For the claimant, Mr Carr contends that it is a team assembled by a chemical company, including a formulation scientist in the agrochemical field and a physical chemist (i.e. essentially the two types of expert witness called by each party). Mr Floyd argues for the defendant that the addressee would be a formulation scientist in the agrochemical field (e.g. Mr Knowles) and not a physical chemist (such as Professor Ryan or Professor Luckham). The difference between the parties on this issue could be slight, in the sense that, even if Mr Floyd is correct, it might nonetheless be that his addressee, or the employer of his addressee, may think it right to consult a physical chemist. However, the difference may be of some significance in relation to the issues which I have to determine.
- In my judgment, the contention on behalf of the defendant is correct. In Richardson Vicks' Patent [1997] RPC 888 at 895, Aldous LJ said:
- It cannot be doubted but that the patent in suit is addressed to a formulation scientist in the agrochemical field. Having considered the patent, in the context of the technical background, which in the main is agreed, it seemed to me unlikely that the addressee would also include a physical chemist, particularly in light of what Aldous LJ said in the passage I have quoted. That provisional view received support, in my judgment, from the evidence. In relation to the main issue which requires to be determined, namely the meaning of "surfactant", the relevant evidence on this point was as follows. Professor Ryan had never been consulted about the practical side of operating a process for making herbicides (apart from the instant case); Professor Luckham thought it unlikely that he would be consulted on the choice of a surfactant; Mr Knowles said he would not find it necessary to consult another chemist for the purpose of deciding whether a particular substance was a surfactant. It was suggested on behalf of the claimant that the addressee would include a physical chemist because such a person would be needed to understand how the invention described by the patent in suit works. I find that unconvincing: not only does the patent in suit not describe how the invention works, but I do not see why it is necessary to understand how it works in order to put it into practice.
- The view that
the addressee of the patent is a formulation scientist in the relevant field,
namely that of agrochemicals, and, indeed, that such a scientist would not
need to consult any other specialist is supported by a statement in the specification
upon which Mr Floyd understandably relies on behalf of the defendant. At page
3 lines 51-52, one finds this:
"The worker of ordinary skill in the formulation art can select a surfactant most suitable for the purpose in view."
- Perhaps rather unusually, therefore, the draftsman of this patent has, at least for one purpose, identified the type of addressee he has in mind and indicated that he is expected to be able to act without having to consult experts in other fields. Of course, that may not be conclusive, in the sense that such addressees might all agree that they would need to consult an expert in another field; however, that is not the case here. Further, the fact that one part of a patent appears to be expressly directed to a specific category of expert does not necessarily mean that the whole of the patent should be treated as directed to that type of expert alone. However (1) the sentence I have just quoted from the patent in suit is directed towards the selection of the surfactant, (2) the issue in the present case is what is meant, and would be understood, by the term "surfactant" and (3) it is common ground that expert evidence is appropriate on that issue. Accordingly, it appears to me that the sentence is of significance in relation to the question of the addressee of the patent in suit.
- Of the four witnesses from whom I heard, it appears to me clear that Mr Knowles is closest, possibly by quite a long way, to the notional addressee of the patent in suit. Professor Hounslow, and the group which he heads at Sheffield University, have particular expertise in granulation, but he very frankly accepted that questions such as whether clay and starch are surfactants in the solid phase was not something upon which he felt qualified to give evidence. Indeed, until he was instructed in this case, Professor Hounslow had not been involved in water-dispersible granules.
- The claimant instructed Professor Ryan as an additional expert witness when it became apparent that it might be somewhat vulnerable in relying on Professor Hounslow alone. Nonetheless, Professor Ryan is not a formulation scientist, but a physical chemist. In cross examination he accepted that he was "a very long way away from the herbicide formulation scientist". Further, when discussing the way in which the patent in suit was drafted, he said that he was "not sure that the person who wrote the patent was approaching this problem in the same way that I am approaching the problem...".
- Although Professor Luckham has had contacts with the agrochemical industry, and has worked on water-dispersible granules, he is not the sort of person to whom the patent in suit is addressed. Indeed, Mr Floyd does not suggest that he does fall within that category; he was called by the defendant essentially for defensive purposes, when the claimant decided to call Professor Ryan in addition to Professor Hounslow. At the priority date, Mr Knowles had been a formulation scientist in the field of agrochemicals for 20 years. He has also been involved with pilot and commercial scale operations. He gave evidence as to what he and experts in the agrochemicals business understood by the term "surfactant", and I see no reason to conclude that an agrochemical formulation scientist of ordinary skill would need to consult a physical chemist as to what was meant by "one or more surfactants" in Claim 1(a).
- As Mr Floyd submitted, the notional addressee is an ordinary, albeit reasonably well qualified and experienced, herbicide formulation scientist. While not suggesting that Mr Knowles is, in any derogatory sense, "ordinary", it seems to me clear that, particularly when compared with the other three witnesses, he is the only one who could fairly be said to fall within that category. So far as the general content of his evidence was concerned, it was internally consistent, as well as being consistent with the evidence as a whole (although there were, inevitably, differences of opinion and emphasis on various points between the expert witnesses). His demeanour in the witness box and the way in which he dealt with the questions put to him did nothing to displace my impression that he was a witness who was doing his best to help the court rather than his client.
- As already mentioned, the defendant contends that the word "surfactant", at least in the context of the patent in suit, has a more limited meaning than that argued for by the claimant. It is common ground that a surfactant works by reducing the energy at an interface between two materials. The claimant contends that the term "surfactant" extends to any molecule which is active at the interface of two phases to modify the surface energy of the substrate, and whether something is a surfactant depends upon the system in which it is used. The claimant accepts that most surfactants are amphiphiles because they are used in the presence of water, but that a surfactant does not have to be amphiphilic (or, as it is sometimes called amphipathic), particularly if it is used in the absence of water. The defendant contends that, at least in the context of the patent in suit, the reference in Claim 1(a) to "one or more surfactants" is limited to materials whose molecules are amphiphilic in nature.
- A number of different factors were put forward in evidence and argument as being relevant to the first issue. It can be dangerous to over-analyse or over-compartmentalise the various possibly relevant factors advanced on an issue of construction; it can involve the risk of not seeing the wood for the trees. However, it is not really possible to do justice to the arguments or to explain the reasons for reaching my conclusion on the first issue, if I do not identify, separate and discuss the various different strands of the expert evidence and argument which were advanced during the hearing.
- As Mr Carr pointed out, the first step - that is the first of the four steps in Claim 1, i.e. Claim 1(a) - which is referentially included in every subsequent Claim, requires the addition of one or more surfactant. That is not an optional aspect of the teaching; it is a mandatory aspect. The nature of the first issue between the parties prompts the obvious question whether it is possible to discern from the patent in suit, and, to the extent that it is admissible on this point, from the expert evidence, the purpose of adding one or more surfactants at the first step.
- The claimant's
case is that Claim 1 requires one or more surfactants to be added at the first
step in order to coat the material, and thereby to overcome the problem of
stickiness and melting, identified at page 2 lines 31-35 and page 3 lines
53-55 of the specification. The defendant, on the other hand, argues that
the purpose of adding one or more surfactant at the first step is to achieve
intimate mixing of the surfactant or surfactants (which, on this assumption,
are, of course, amphiphilic) so that the surfactant or surfactants operate
more effectively at the next stage, namely that described in Claim 1(b) of
the patent in suit ("the second step"). Each of these explanations is open
to attack.
- Three points can be made against the claimant's interpretation. First, there is no relevant teaching, indeed no suggestion of any teaching anywhere in the specification, that deals with solving the "sticky propanil" problem. Indeed, the first passage dealing with the problem mentions micro-encapsulation as a possible solution, and the second passage simply asserts that "[f]low aids such as clays or silica particles may be used to minimise these problems" and goes on to suggest certain proprietary flow aids.
- The second problem with the claimant's explanation as to why surfactant is added at the first step is the claimed discovery at page 2 lines 45-47 of the patent in suit, which appears to encapsulate the alleged inventive concept. It is "a process for producing dispersible granule formulations" which have "good suspensibility and dispersibility characteristics, and which resist attrition". Thus, there is, at least in express terms, no suggestion of the discovery involving a new method of overcoming the "sticky propanil" problem. The focus of the alleged discovery is good suspensibility dispersibility and attrition characteristics.
- Thirdly, if the claimant is right, it is a little difficult to understand why the patent in suit limits the substances which assist in the milling process to surfactants. Even on the claimant's wider meaning of the word, there would be materials which would assist in the milling of propanil which are not surfactants. This was clear from Professor Ryan's evidence in cross-examination. The effect of his evidence was that not all dispersants in the milling at the first step are surfactants. If that is so, why, one asks rhetorically, did the draftsman limit the materials added to the propanil at the first step to surfactants, if their function is as contended for by the claimant.
- I do not consider that it can be fairly contended that, because the specification mentions the "sticky propanil" problem, it must be assumed to claim to solve it. Unlike many patents, there is no contention, or even suggestion, in the patent in suit that the alleged discovery overcomes all the problems identified in the specification. Thus, there is no sensible way in which the patent in suit can be read as even contributing anything new towards dealing with the "dust problem" identified in the course of the passage at lines 14-23 on page 2 of the patent in suit: all that is said in that connection is at page 4 lines 12-13, which refers to "the preferred method of extrusion", as to which the patent in suit contains no teaching or claims.
- This also impinges on the possible explanation why, on the claimant's case, the materials at the first step are limited to surfactants. It may be said that the innovative concept, on the claimant's case, was the use of surfactants, as opposed to substances which keep the milled propanil particles apart in some other way, at the first step. If that were correct, one would have expected some express suggestion, indeed some teaching, on that aspect. Yet there is none.
- The claimant also suggests that, on its case as to the purpose of adding surfactant at the first step, the surfactant is acting as a flow aid or as a dispersant or as a disintegrant at that stage. I do not believe that is supported by the terms of the patent in suit or, at least on my view, by the expert evidence.
- First, flow aids. At least in the context of the specification, the contention that surfactants are, or can include, flow aids, is not a happy one. As I have mentioned, at lines 25-26 of page 3 of the specification, the draftsman tells one that "surfactant" is used in the patent in suit "to include materials which may be referred as emulsifying agents, dispersing agents and wetting agents". Further, in the course of the specification, the draftsman appears to have been tolerably careful in distinguishing between dispersing agents, wetting agents, flow aids, defoaming agents and disintegrants. Obviously, as the draftsman plainly contemplates, some substances can and will fall within more than one of those categories, but I do not think that significantly detracts from the force of the point.
- Although Professor Ryan suggested in his evidence in chief that "one or more surfactants" were added at the first step to assist the milling of the propanil, he accepted that, when looking at the specification, this view is difficult to marry up with the reference to "flow aids such as clays or silica particles" at page 3 line 54. As I have said, flow aids are treated as different from surfactants in the specification (compare page 3 lines 25-28, explaining surfactants, with page 3 lines 53-57, discussing flow aids). Indeed it was in connection with this point that Professor Ryan said that he was not sure that the draftsman of the patent "was approaching this problem in the same way that I am approaching the problem..."
- The attempt on behalf of the claimant to suggest that flow aids, at least as that term is used in the patent in suit, can include surfactants runs into a further difficulty. At least until they were instructed in this case, neither of the claimant's experts, Professor Hounslow and Professor Ryan, had heard use of, or had used, the term "surfactant" in relation to particulate materials in the dry state; the flow aids referred to in the patent in suit are, of course, such materials.
- As to dispersing agents, it is true that the patent in suit states that "surfactant" could include "dispersing agents" (page 3 lines 25-26). However, I do not consider that this points to the conclusion that the addition of a surfactant or surfactants at the first step was as a dispersing agent in an anhydrous dry medium to keep the "sticky propanil" particles apart. Although both the claimant's experts gave evidence which could be said to support this reading of the patent in suit, I was not persuaded by it. The persuasiveness of their evidence on this aspect was not assisted by the fact there was a difference between them. Professor Hounslow described a surfactant as a material which "operates by energetic interactions at an interface", whereas Professor Ryan thought that any material, even if particulate, would be a surfactant if, at any rate for the purposes of the first step, it kept the particles of propanil from agglomerating; according to him, it would not matter how the material worked, whether it was particulate, provided it performed this function it was a surfactant. On this basis, the flow aids referred to in the specification were surfactants, and he accepted that, on this basis, oil would be a surfactant as well. Indeed, even the micro-encapsulation referred to at page 2 lines 31-35 of the specification would involve a surfactant. On this basis also, as Mr Floyd points out, gas absorbing onto a metal surface, indeed water absorbing onto propanil particles, would be a surfactant activity, which suggest a far wider concept of surfactant than that envisaged by the patent in suit, particularly in light of the evidence of Professor Luckham and Mr Knowles.
- In his cross-examination, Professor Luckham said that, at least in his view and experience, while a material could be capable of acting as a surfactant other than in a liquid phase, it could not act as a dispersing agent other than in a liquid phase. He said that he would be surprised if people in industry thought of dispersing agents as materials acting in anything other than the liquid phase. Mr Knowles said that:
- Further, Mr Knowles knew nothing of the idea of powdered ingredients or particles acting as dispersants in the dry state from his long experience in the agrochemical industry. He agreed with Professor Luckham, and said that "they work[ed] from a solution in water and only in the molecular state by absorption onto surfaces"; he immediately went on to correct that by expanding the reference to water to "other liquids, but certainly not in the dry state". However, he went on to say that, in the context of subject matter of the patent in suit, concerned with water-dispersible granules, it was "inconceivable" that the liquid medium "could be anything other than water". When dealing with what he understood by dispersants or dispersing agents, he made what amounted to the same point. In the context of the agrochemical industry, dispersants were understood to be substances which acted in that capacity in "any liquid system, ... but not a dry system" but he had "got [his] mind on the patent in suit, which is an aqueous system".
- I have little hesitation in preferring the evidence of Mr Knowles and Professor Luckham on this issue. As already mentioned, of the four expert witnesses who gave evidence in this case, I consider that Mr Knowles is the closest to the notional addressee of the patent in suit.
- Quite apart from this, the dispersion with which the patent in suit is concerned appears to me to be dispersion in water, and that suggests that the dispersing agents which the draftsman had in mind were dispersing agents in water, and, in my view, they must amphiphilic. Indeed, that was accepted by Professor Ryan, the claimant's expert physical chemist, when he said:
- Although Mr Carr nonetheless seeks to argue that, in the context of the patent in suit, dispersing agents were not so limited, it seems to me that his argument (and the evidence of Professor Ryan) faces a further difficulty from another passage in the specification, at page 3 lines 42-43:
- I do not think that the words "for example" assist the claimant in this connection, because the only liquid mentioned in the specification, and the only liquid mentioned in the claims, is water. Anyway, this passage fairly plainly limits dispersants to those which act as such in liquids, not in the dry phase, as is involved at the first step. Accordingly, the claimant's notion that the reference to "one or more surfactants" in the first step is to one or more dispersing agents which act as such in a non-liquid phase is inconsistent with the definition of dispersing agent in the patent in suit itself.
- Before concluding on the issue of dispersants and dispersing agents, it is right to mention three subsidiary matters. Reference was made by Professor Hounslow to work that had been done on the interaction of clay with sodium pentaborate. However, they had only been studied in recent months, and cannot therefore conceivably have been in the mind of the addressee of the patent in suit at its claimed priority date. Reference was also made in the cross-examination of Professor Luckham to dispersants with only hydrophilic ends, in the ceramics industry. However, it seems to me that the course of that cross-examination is a good illustration of how important it is to construe words in their context, in this case the words "surfactant" and "dispersants" in the context of the patent in suit. Two examples from the cross examination will suffice:
- I turn to the
suggestion of the claimant that a disintegrant could be a surfactant. For
the purpose of the patent in suit, it seems to me that the two concepts are
very different. First, disintegrants are not included in the type of substances
which are mentioned in the patent in suit as being within the category of
surfactants ("emulsifying agents, dispersing agents, wetting agents" - lines
26-27 page 3). Secondly, there is the observation that the recommended disintegrants
"have adverse effects on the propanil granules", a rather odd observation
if they were intended to be included as surfactants. Thirdly, the Example
on pages 10-11 of the patent in suit shows that the addition of increasing
amounts of specified disintegrants has an adverse effect on the beneficial
effect of a surfactant, as Professor Hounslow accepted. Further, disintegrants
are said to be "water soluble" (page 4 line 3 of the patent in suit); that
does not suggest that the draftsman had in mind materials which would be used
at the first step, which involves air milling and is anhydrous.
- The defendant's explanation as to why the surfactant is added at the first step is, as I have mentioned, to ensure that the surfactant is intimately mixed with the propanil so as to enable it to perform its function at the second step. However, there is no reference anywhere in the patent in suit to the need for intimate mixing at the first step. That is true whether one looks at the specification or at the Examples. Accordingly, there is obvious force in Mr Carr's point on behalf of the claimant that the defendant's explanation as to the addition of surfactant at the first step gets no support from anything in the specification or Examples in the patent in suit, given that, on the defendant's construction, the surfactant only operates at the second step.
- The claimant also can derive some assistance from the fact that neither Professor Luckham nor Mr Knowles said that, as at the claimed priority date, there was any perceived problem at the second step which would be avoided by the intimate mixing of propanil with a surfactant at the first step. However, Mr Knowles said in his evidence:
- He then went on to expand on this in a little more detail both in his proof and in answers to questions from Mr Floyd. He was cross examined about this view by Mr Carr, but nothing which was put to him and nothing he said shook his evidence on this point. Mr Carr correctly points out that the only documentary evidence of any research suggesting the desirability of intimate mixing is in a book edited by Mr Knowles, which was published in 1998. However, I have no reason to think that the evidence I have quoted from Mr Knowles did not reflect what was known to, and would have been appreciated by, the appropriately qualified and experienced addressee as at the priority date.
- Mr Carr also relied on some answers given by Mr Knowles in cross-examination which, he suggested, showed a misunderstanding of Claim 1 in the patent in suit, because Mr Knowles envisaged wetting agents or dispersing agents being added at the second step, particularly if they were liquid, whereas the first step of Claim 1 made it clear that surfactants had to be added at that stage. I do not think that is an entirely fair interpretation of Mr Knowles's evidence. To my mind what he was saying was this. In so far as the dispersing agents or wetting agents were liquid, they could not be added at the first step and would have to be added at the second step. His evidence seems to have been to the effect that some of the proprietary wetting agents identified in the specification were liquids, whereas others were solids; however, all the dispersing agents were solid. In those circumstances, as I read Claim 1 of the patent in suit, in light of Mr Knowles's evidence that liquid surfactants could not be added at the first step, any solid surfactant employed in the process described in Claim 1 is required to be added at the first step, whereas any liquid surfactant would be added at the second step. The absence of any reference to dispersing agents at the second step is therefore explicable on Mr Knowles's evidence by the fact that no liquid dispersing agents appear to have been included in the examples, or were suggested by anyone in the evidence, so far as I understood it. Further, the addition of an optional wetting agent is mentioned at the second step, it is explicable by the fact that a liquid wetting agent could not, as Mr Knowles explained, be added at the first step. In so far as Mr Knowles's evidence was inconsistent with this conclusion, I do not think he was right; however, it is fair to him to say that I do not read his evidence as being inconsistent in this way.
- It is inherent in the forensic process that every aspect of the specification of the patent in suit which appears to cast favourable light on a party's contention will be put forward by its representatives as a factor to be taken into account when determining the meaning of a Claim in that patent. That process can be dangerous, not so much, perhaps, for the advocates, but for the tribunal deciding the issue, because it inevitably involves careful consideration of every part of the patent in suit, including the specification, which could be of relevance. The process therefore encourages the court to adopt what Lord Diplock deprecated as a "detailed semantic analysis" of the specification to see if one can tease out of it features which appear to assist the resolution of the point in dispute. While it is obviously right to construe the words of a claim in the context of the whole of the patent in suit, including the specification, one must avoid the trap of being too easily persuaded to invoke words in the specification to cut down the natural and wide meaning of the words of the claim. Indeed, that was the trap into which I fell in Cartonneries (unreported).
- In the present case, it appears to me that the terms of the specification are of particular significance at least in so far as they seek to define "surfactant" or to indicate directly what the draftsman of the patent in suit had in mind when using that term. Two passages are, in my judgment, of particular relevance. The first is at page 3, lines 25-27, where, as I have mentioned, one finds this:
- Three points may be made about this. The first is the fact that "surfactant" is expressly stated to be "used in the broad sense". At least taken on its own, that suggests that, if the word "surfactant" has a broader meaning (such as that, for instance, intended for by the claimant) and a narrower meaning (such as that contended for by the defendant) the draftsman has in mind the wider meaning. However, one cannot stop with the words "broad sense". They must be seen in their context. That brings me to the second point; the draftsman goes on to refer to the fact that the term includes "materials which may be referred to as emulsifying agents, dispersing agents and wetting agents". It is clear that all "wetting agents" are amphiphiles. Initially, the claimant contended that not all "dispersing agents" would be amphiphiles. However, it seems to me that, reading the patent in suit as a whole, that contention cannot be right. For the reasons already discussed, when the patent in suit refers to dispersing agents it is limited, in my view, to amphiphiles (see especially the specification at page 3 lines 42-43).
- I have not so far considered the effect of the reference to "emulsifying agents". I am bound to say that that expression in the context of the patent in suit appears to be somewhat mystifying. Mr Knowles said in his evidence that he regarded emulsifying agents as surfactants which "emulsify oils into water and play a major role in the stabilisation of pesticide formulations and impart good shelf life". Two points can be made about that, both of which were expressed by Mr Knowles, and which I accept. First, such emulsifying agents would be amphiphilic (because again they are concerned with surfactant activity in water); secondly, they are not relevant to the claims of the patent in suit because that is not concerned with "forming emulsions [because] the particles are solid and not oily droplets", to quote Mr Knowles again.
- The third point to be made about the passage at page 3 lines 25-27 of the specification is the statement that surfactants "may comprise one or more surfactant selected from the anionic, cationic and non-ionic type". During cross examination, Professor Ryan accepted that, even though, on his view, not every surfactant was amphiphilic, any surfactant "selected from the anionic, cationic and non-ionic type" would be amphiphilic. He accepted that "it would not be appropriate to describe a surfactant which was not amphiphilic as being selected from the anionic, cationic and non-ionic type".
- The other provision of relevance in this context is at page 3 line 50 of the specification, where it is stated that:
- As already indicated, I am satisfied that, at least in the context of this patent in suit, all "dispersing agents" and "wetting agents" are amphiphiles. If "all surfactants" within the meaning of that expression in the patent in suit, act as dispersing agents and as wetting agents, it must follow, in my judgment, that all surfactants, as referred to in the patent in suit, are amphiphiles. As I have said, Professor Ryan accepted that "surfactants which function as wetting and dispersing agents must be amphiphiles".
- It is true that Professor Hounslow appeared to suggest that this view may be called into question in light of the use of the words "to some degree" but I am unpersuaded that this takes matters any further. Some surfactants may act more effectively as dispersing agents than as wetting agents, some may work more efficiently as wetting agents than as dispersing agents, and some may not perform particularly efficiently in either capacity. However, the words at page 3 line 50 appear to me naturally to indicate that, when the draftsman refers to a surfactant, he has in mind something which will act to some degree both as a dispersing agent and as a wetting agent, which means that they must be amphiphilic.
- As is not uncommon in a case involving issues such as the present, each party has referred to definitions and uses of the word "surfactant" in published material available at the priority date. Thus, in Atkin on "Physical Chemistry" one finds this:
- On the other
hand, in "Introduction to Colloid and Surface Chemistry" by Shaw, there is
this:
"The strong adsorption on such materials at surface or interfaces in the form of an orientated monomolecular layer (or monolayer) is termed surface activity. Surface-active materials (or surfactants) consist of molecules containing both polar and non-polar parts (amphiphilic)."
- Finally, I was referred to the Royal Society of Chemistry's Handbook "Surfactants Europa" which contains the following:
- While it would
be wrong to ignore definitions or uses of a particular word in text books
and other publications, it can obviously be dangerous to rely upon them in
a case such as this. The question which has to be determined is not what the
word "surfactant" means in abstract, let alone what it means in the context
of other publications directed to a different, or at any rate wider, class
of person than the person to whom the patent in suit is directed. The cases
to which I have referred emphasise the danger of trying to construe a word
or expression acontextually, that is outside the context of the patent in
which it is found. There can be even greater danger, I think, if one is seeking
to construe the meaning of a word in one context by reference to how it is
used in another context.
- Nonetheless,
where, as here, one party is seeking to give a word a significantly narrower
meaning than is suggested by the other party, some assistance may well be
found in passages such as those I have cited.
- The definition
of "surfactant" in Atkin is of some assistance to the claimant for two reasons.
First, it does not limit surfactant activity to the liquid phase; secondly,
it does not appear to limit surfactant to amphiphilic substances. However,
it is interesting to note that the one example given by Atkin is one which
would involve only an amphiphile as a surfactant, and would, I think, only
be likely to apply where one of the phases is liquid. Further, it does not
seem to me surprising that a term should have a substantially wider meaning
to physical chemists generally than it would have in the context of a specific
aspect of teaching in a patent directed specifically to the agrochemicals
industry. Quite apart from this, at least in the context of the patent in
suit, it is clear from the expert evidence that Atkin's definition would have
to be cut down by a functional qualification, namely keeping particles apart.
It is neither necessary nor appropriate for me to consider whether this qualification
should be imported into Atkin's definition. For all I know, the definition
may not need amendment, at least on one view of the meaning of "surfactant"
to physical chemists generally. I merely make the point in order to show how
a definition of a word in a text book may be too wide for the purpose of defining
how the word is used in another, more specialised, context, such as a patent.
- The definition
in Shaw is of help to the defendant. However, it can be said on behalf of
the claimant that the second sentence of the passage I have quoted from Shaw
may not have been intended to be exclusive. Even if that is right, however,
it does seem to me that the fact that a text book gives a narrower, rather
than a wider, definition of a word is of some assistance to the contention
that, when used in a specialist context, the word must have been intended
to have that narrower meaning. However, it would be wrong to suggest that
I think that that point, taken on its own, gets the defendant very far, particularly
in light of the definition in Atkin.
- The Royal Society
of Chemistry's publication is, I think, in principle, of rather greater assistance
than a text book, because it is intended to be a practical document, as is
the patent in suit, whereas a text book has a somewhat different purpose.
Mr Carr was able to point to Professor Luckham, who produced the extract I
have quoted from "Surfactants Europa", to one or two passages which rather
weakened the effect of the extract. In particular, there was the statement
that "there are many definitions of "surfactant" depending on personal preference
and field of usage". However, the extract referred to by Professor Luckham
is of some assistance to the defendant, in my judgment.
- In the end,
neither Mr Floyd nor Mr Carr places a great deal of weight on these definitions,
and, in my judgment, rightly. Nonetheless, they are of some limited assistance.
- During the course
of argument, reference was made by Mr Carr to some of the other Claims of
the patent in suit, and in particular Claims 4, 5 and 10. Claim 4 narrows
Claim 1 (and Claims 2 and 3) to the extent of adding a dispersant at the second
step. Claim 5 is a variant in that it specifically involves the addition of
dispersant and flow aid at the first step, it involves a smaller particle
size at the first step, it involves adding less water at the second step,
it has a mandatory, rather than an optional, wetting agent at the second step,
and it requires the paste at the second step to be extruded. Claim 10 is a
variant on the preceding claims in that it requires the dispersible granule
to be "substantially free of disintegrant".
- While Mr Carr
places some reliance on the effect of these three later Claims to support
the claimant's construction of Claim 1, and in particular of the reference
to "one or more surfactants" in the first step, I do not find his arguments
convincing. His main point, at least in opening, was based on Claim 10. He
points out that the defendant's case is that disintegrants cannot be surfactants
for the purpose of the patent in suit in light of the passage at lines 3-8
on page 4 of the specification, which describes certain disintegrants as having
"adverse effects on the propanil dispersible granules". He argues that, given
that Claim 10 involves the addition of a disintegrant, the defendant's construction
cannot be right, and that it supports the view that a substance can be a disintegrant
and not a surfactant in one medium, such as water, but a surfactant in another
medium, such as the anhydrous air during the milling at the first step.
- First, it seems
to me that there is nothing in that argument which displaces the view that
the draftsman has distinguished between surfactants, which are desirable,
and disintegrants, which are undesirable, for dispersion purposes (compare
page 3 line 50 with page 4 lines 3-8 of the specification). Secondly, I consider
that Mr Floyd is correct in contending that Claim 10 has been included by
the draftsman for the normal reason, namely to protect the patentee if the
earlier claims are too wide. The draftsman has adopted the familiar scheme
of each successive claim being, at least generally, narrower than the previous
claim, with a view to giving a maximum potential protection for the patentee.
I do not see how the mere fact that the specific addition of disintegrant
in Claim 10 is of any real assistance to the issue of construction of Claim
1(a).
- So far as Claim
5 is concerned, it represents, as I have mentioned, really a narrowing down
of Claim 1 (and indeed of Claims 2 to 4) in a number of respects. As for Claim
4, at least if the defendant is correct, it is the first time that the problem
of "sticky propanil" has been addressed, namely by the express addition of
flow aid at the first step. Again, I do not see how they help on the issue
dividing the parties. On the claimant's case, flow aid could be within the
"one or more surfactants" at the first step of Claim 1, but it need not be.
On the defendant's case, flow aid might or might not be added at the first
step of Claim 1, but the draftsman has narrowed the ambit of the first step,
or, to put it another way, has been specific that flow aid has to be added
at the first step, when drafting Claim 5. In the same way the draftsman has
only specifically added a defoaming agent for the first time at Claim 4. Further,
the fact that the flow aid solution to one problem (which the specification
does not suggest is an inventive aspect of the claimed discovery) comes in
for the first time at Claim 5 is no more significant than extrusion coming
in for the first time at Claim 3.
- To a substantial
extent, I have already discussed the expert evidence relating to the first
issue in the preceding sections of this part of the judgment. Where, as here,
there is a dispute between the parties as to the meaning of a particular technical
word in a patent (or indeed in any other document), and each party leads expert
evidence to support its favoured construction, the net effect of that evidence
is often to confuse rather than enlighten. That is not meant to be critical
of such expert evidence in general, or of the expert evidence in this case
in particular. There are cases where an expert witness changes his mind, can
be shown to be proceeding on a false assumption, or can be shown simply to
be wrong. Where that does not happen, the court can be said to be faced with
the additional problem of resolving a dispute between reasonably credible
expert witnesses, in addition to having to resolve the centrally relevant
issue, namely the meaning of the word in question in the context of the particular
document in which it is found.
- Professor Luckham's
evidence was to the effect that the word "surfactant" was generally understood
in the field of physical chemistry as meaning an amphiphile. As Mr Carr said,
once one accepts that a surfactant must be an amphiphile, then the resolution
of the first issue between the parties is facile. In those circumstances,
unless "surfactant" must in all circumstances mean an amphiphile, and cannot
have the wider meaning contended for by the claimant, the rest of Professor
Luckham's evidence is of limited value: it puts the cart before the horse,
in that it decides what "surfactant" means generally and in the patent in
suit, and then proceeds to explain the patent in suit on that basis.
- Accordingly,
I regard Professor Luckham's evidence, in so far as it relates directly to
the meaning of the word "surfactant" in the patent in suit, as being of very
limited value. However, three further points should be made. First, as a physical
chemist, his view of the meaning of the word "surfactant" is of itself of
some significance. Secondly, as will be appreciated from observations made
earlier in this judgment, Professor Luckham gave useful evidence on various
other aspects, including the meaning of other technical words in the patent
in suit. Thirdly, as I have mentioned, Professor Luckham was not put forward
as the defendant's principal expert witness: he was an additional expert called,
as it were, to counter Professor Ryan, whom the claimant decided to call in
addition to its original expert witness, Professor Hounslow.
- Turning to the evidence of Professor Hounslow, he was primarily concerned with the meaning of the word "disintegrant" in the patent in suit. Having described the meaning as "flexible", he, correctly in my view, went on to consider the meaning of the word in the context of the patent in suit, and then turned to the question of whether a disintegrant could be a surfactant. He had three or four years working as a development officer for ICI's Australian operation in the early 1980s, but since then has held university posts. His particular expertise is in granulation. Although I accept that he believed that, even in the context of the patent in suit, disintegrants were, or at least could be, surfactants, I consider that his evidence was of limited value, not least because, as Mr Floyd argued, he is, and was at the priority date, far too skilled to be treated as the addressee of the patent in suit. Furthermore, as I have also mentioned, the reason the claimant decided to call Professor Ryan was because the question of whether certain substances could be termed "surfactants" was not really within Professor Hounslow's area of expertise.
- As to Professor
Ryan himself, I have already explained why he cannot fairly be said to be
the notional addressee of the patent in suit. I have also mentioned that,
at least in one important respect, he accepted that the draftsman of the patent
in suit did not appear to have approached the meaning of the word in the same
way as he does. His view as to the meaning of the word "surfactant", if approached
acontextually, was in accordance with the contention of the claimant, rather
than that of the defendant and its equivalent expert, Professor Luckham. It
is fair to say that, so far as his evidence in chief was concerned, Professor
Ryan appeared to approach the question of the meaning "surfactant" in the
patent in suit with a more open mind than did Professor Luckham. He concluded
that, in light of the passage at lines 25-28 on page 3 of the patent in suit,
the draftsman had used the word "surfactant" in the way in which Professor
Ryan would have understood it acontextually. However, as a result of his cross-examination,
I think that his evidence was as helpful, or as unhelpful, as that of Professor
Luckham. Each of them had a fairly clear idea as to what he thought "surfactant"
meant, and each of them approached the patent in suit with that thought very
much in mind.
- As with Professor
Luckham, the evidence of Professor Ryan was nonetheless of some help, taken
as a whole. In my judgment, Mr Floyd got further with Professor Ryan than
Mr Carr did with Professor Luckham, and I have in mind in particular the concession
by Professor Ryan, which I have already mentioned, that the draftsman of the
patent in suit did not appear to be approaching at least some of the technical
expressions in the same way as Professor Ryan would have done. Like Professor
Luckham, and indeed Professor Hounslow, Professor Ryan is not the sort of
person to whom the patent in suit should be treated as being addressed. At
best, each of them is the sort of person who might conceivably have been consulted
by the notional addressee, but, in light of the evidence of Mr Knowles (to
which I turn) and the way in which the patent in suit is drafted, I do not
think it likely that that would have happened.
- As I have mentioned, Mr Knowles is within the scope of the notional addressee of the patent in suit. Having explained the role of water dispersible granules in the agrochemicals business, and the role of extrusion processes in that business, he proceeded to describe what he understood the process described by the patent in suit. He then went on to explain what he understood by the expressions "surfactants", "wetting agents", and "dispersing agents", and explained why he considered that the word "surfactant" in the context of the patent in suit was limited to amphiphiles. It could be said that, in some respects, his testimony went into areas on which evidence is strictly not admissible, but that is always a danger in a case where expert evidence is admissible on a limited topic, and it is fair to say that a similar point may be made in relation to the other three experts. It should also be said that this is not intended to be an adverse criticism of them as witnesses.
- However, dissecting
out the essence of Mr Knowles's admissible and centrally relevant evidence,
it seemed to me that, as a person representing the notional addressee of the
patent in suit, he was an honest witness, whose testimony as to how "surfactant"
in the context of the patent in suit would have been understood by the notional
skilled addressee was convincing. That evidence was to the effect that "surfactant"
would be understood to be referring to an amphiphile. As I have already mentioned,
it would be unfair to the claimant, and indeed on Mr Carr, to leave this topic
without mentioning that the expert evidence was not all one way. Although
they were not, by virtue of their disciplines and knowledge, as helpful witnesses
as Mr Knowles, Professor Hounslow and Professor Ryan did make some valid points,
and, as is probably clear from the earlier sections of this part of my judgment,
there are undoubtedly some factors which favour the claimant's case. Nonetheless,
principally because of his expertise and experience, Mr Knowles's evidence
was of more value than that of the other three expert witnesses. In sum, he
appears to have approached the issue in a helpful and correct way in his evidence,
and to have expressed a view on the central issue which was, in my judgment,
honestly held and reasonably convincing.
- With the exception
of the claimant's reliance on other Claims of the patent in suit, all the
other factors relied on by the parties appear to me to have some force. In
the end, while there are features of each factor upon which the claimant can
justifiably rely, it appears to me that the balance of advantage on each factor
lies with the defendant. So far as the body of the specification is concerned,
the claimant does get some assistance from the fact that the draftsman says
that the word "surfactant" is used in the patent in suit "in the broad sense".
However, the reference to surfactants being "dispersing agents and wetting
agents", particularly in light of the subsequent definitions and explanations
of those terms in the specification, significantly assists the defendant.
So too is the statement that the surfactant should be "selected from the anionic,
cationic and non-ionic type". The reference to surfactants acting as dispersing
agents, particularly in light of the definition and explanation of "dispersing
agents" in the patent in suit also supports the defendant's case.
- I consider that
the defendant's case is further assisted by the expert evidence. While not
in any way questioning the expertise of the other three witnesses, it appears
to me that Mr Knowles was the only witness who had the experience and discipline
of the notional addressee, whose identity is somewhat unusually expressly
suggested in the specification. He was an honest witness, whose evidence was
entirely consistent and stood up to cross examination. It would be unfair
on Mr Carr not to accept that he made some valid points to and about Mr Knowles,
but, viewing matters overall, they do not cause me to doubt his evidence as
to the understanding of formulation scientists in the agrochemical field of
the word "surfactant" and how that word would be understood at Claim 1(a)
of the patent in suit, namely as an amphiphile.
- The two text
books pointed in somewhat different directions, but, particularly when one
remembers the contents of the publication of the Royal Society of Chemists,
it seems to me that the balance is in favour of the defendant, albeit mildly,
on this score also. As I have already said, this is a comparatively minor
aspect.
- The question as to why the surfactant is added at the first step is an important one, as Mr Carr rightly says, because one is here concerned with the question of construction of a document which is intended to have practical effect. If one confines oneself, as a lawyer, to what is said in the patent in suit, then there is considerable force in Mr Carr's point that it is difficult to discern the purpose of adding one or more surfactants at the first step. For the reasons already given, I am quite unpersuaded by the claimant's contention that it is for the purpose of assisting at the milling stage. There is no teaching, or even any claim to any discovery, to that effect anywhere in the patent. On the other hand, in the absence of expert evidence, the idea that the purpose is to assist intimate mixing of propanil and surfactant to optimise the second step is the purest speculation, albeit not unreasonable speculation. However, Mr Knowles, who seems to me to be close to the epitome of the notional addressee, appears to have had no difficulty in understanding the purpose as being intimate mixing, and while Mr Carr challenged him in cross-examination, and maintained his challenge in his closing speech, I accept Mr Knowles's evidence on the point.
- In all these circumstances, I have come to the conclusion that the defendant succeeds on the first issue, and, therefore, in order to be a surfactant for the purpose of the patent in suit, a substance must be amphiphilic in nature.
- As I have mentioned, this question falls to be considered, irrespective of my conclusion on the first issue. The defendant's Process B is confidential, and therefore I shall only describe it to the extent strictly necessary for the purpose of explaining my reasoning in relation to the second issue. Under Process B, propanil is milled at the initial stage. The only material added to the propanil prior to that milling stage are both or either of two proprietary substances marketed as Paselli SA2 ("Paselli") and China Clay GTY ("China Clay"). Paselli is partially hydrolysed potato starch, and China Clay is, as its name indicates, a naturally occurring clay mineral deposit.
- On the defendant's construction of the patent in suit, and in particular of the words "one or more surfactants" in Claim 1(a), which I have accepted, a surfactant must be amphiphilic in nature. Neither Paselli nor China Clay is amphiphilic, and therefore their addition to the propanil at the first step of Process B does not, at least on the face of it, involve the defendant infringing the patent in suit. However, the claimant nonetheless contends that Process B infringes the patent in suit, in that the addition of Paselli and/or China Clay at the first stage, and the addition of surfactants at the second stage, of Process B involves a variant which, on analysis, does not prevent Process B infringing.
- In the context of this case, then, the variant between the allegedly infringing process and the patent in suit is the use of a non-amphiphile in place of an amphiphile in the first step, coupled with the use of an amphiphile at the second step. In order to decide whether the claimant is right in contending that the variant does not prevent Process B from being infringing, it is, of course, necessary to ask the three Improver questions identified by Hoffmann J. I turn to consider those questions.
- Does the variant have a material effect on the way that the claimed invention works? Although the evidence relevant to answering this question could have been more helpful, I have reached the conclusion that the answer to the question is in the affirmative. During the second half of 1995, in connection with opposition proceedings in the EPO, and pursuant to a request from the EPO, the claimant carried out an experiment, which it communicated to the EPO on 11th December 1995. That experiment involved the preparation of three formulations. The first two formulations involved milling propanil with chalk or clay, and then adding dispersants with water. The third formulation (following the teaching of the patent in suit) involved milling the propanil with clay and a dry dispersant, and then adding water. The claimant then treated the formulations in the same way, namely "mixing [them] to a consistency suitable for extrusion" and then extruding them and drying them "in an identical manner". Having set out the results in quantitative terms, the claimant justifiably described the result as "demonstrat[ing] the unexpected advantages achieved by following the process of the [patent in suit]".
- When this experiment was put to Professor Hounslow, he said that he needed to know more details of the experiments before he regarded them as helpful in connection with the present case. However, he accepted that the second of the formulations in the experiment was "very much akin to... Process B". He also accepted that the result of the experiment showed not only "worse initial figures" for the first two formulations as against the third formulation, but it also showed relative deterioration in the products manufactured from the first two formulations when compared with that from the third formulation. This, then, appears to be evidence from the claimant's own experiment, to suggest that the answer to the first Improver question is yes.
- The claimant suggested that the fact that Process A and Process B both produce a saleable product points strongly in favour of the answer to the first Improver question being in the negative, because, of course, Process A does not contain the variant in question. In my judgment, however, that will not do. The point would obviously be powerful if it could be shown that the product of the two processes was indistinguishable, but that was not the thrust of the claimant's case. Even then, it would be conceivable that there was another difference between the two processes which, as it were, cancelled out the difference. I accept that that might be a fanciful notion, but, for the reasons I have indicated, I do not have to consider it, because there is no evidence to show that the products of the two processes are, in fact, identical.
- Accordingly, I conclude that the answer to the first Improver question is in the affirmative. That makes it strictly unnecessary to consider the remaining two Improver questions, but, as they were fully argued, it is right that I should do so.
- I turn to the second question, namely whether it was obvious that the variant would have no material effect. The principle expert witness whose evidence was relevant on this point was Professor Ryan, one of the claimant's experts. While pointing out that the question he had been asked in cross examination contained a double negative he said that "it is not obvious to me that it [sc. the variant] will not have any effect". I should say that the effect in question was the behaviour of the pre-mix formed at the first step on the addition of water (and an optional wetting agent) at the second step. In re-examination, he was a little less sure, but the effect of what he said was that he was not sure whether there would be a significant difference as a result of the variant, but he thought that there probably would be.
- Further, always remembering that I am proceeding on the assumption that the defendant's contention on the first issue is correct, the purpose of including a surfactant at the first step of Claim 1 of the patent in suit is to obtain intimate mixing of propanil and surfactant or surfactants. On that basis, the variant involved in Process B must have a material effect, virtually by definition. On the face of it, that could be said to be an unattractive point given that, as I have mentioned, there is nothing in the patent in suit which claims, or even suggests a claim, to the effect that any aspect of its inventive concept is involved in the intimate mixing. However, assuming that the reference to "one or more surfactants" in Claim 1(a) is to one or more amphiphiles, then, at the very least, the purpose of adding surfactants at the first step must be to assist at the second step. Accordingly, adding Paselli and/or China Clay, and not having any amphiphile, at the first step, as is involved in Process B, would, at least on the face of it, be perceived as having a material effect on the way in which the invention claimed by the patent in suit works. Taken together with Professor Ryan's evidence, this satisfies me that the answer to the second Improver question is no.
- I turn then to the third question (which can only sensibly be considered on the assumption that I have answered the first two Improver questions differently, namely to the effect that the variant does not have, and would at the priority date have been perceived as not having, a material effect upon the way in which the claimed invention works). The third question is whether the appropriate addressee would nonetheless have understood that the patentee intended that strict compliance with the primary meaning was an essential requirement of the invention.
- In my view, there is force in Mr Floyd's contention that, if the defendant can show that a narrower construction involves a patent claiming a process which is exclusively novel, whereas a wider construction would extend to processes which are not novel, that is a powerful argument in favour of the narrower construction. I think that that submission derives support from what was said in Improver itself at [1990] FSR 181 at 197.
- In this connection, both the claimant's experts, Professor Hounslow and Professor Ryan agreed that it was "extremely well known" that materials such as clay or silica were useful in stopping particles sticking together in a dry milling process. However, Professor Ryan agreed in cross examination that "the suggestion of using an amphiphilic surfactant as a milling aid" was "rather interesting" and "quite different from the old milling aids everybody knows about".
- In these circumstances, if the Claim is limited to amphiphiles, the draftsman of the patent in suit is identifying a category of materials with a particular ability to interact, because of their chemical properties (its constituent molecules having one hydrophilic end and one hydrophobic end) which had apparently not been suggested for that purpose previously. On the other hand, if the Claim is treated as not so restricted, the category will extend to materials which would interact with the propanil in the same way as known particulate materials, with the result that, albeit only to that extent, nothing new is claimed by the patent in suit.
- It follows that,
in my view, the answer to the third Improver question is favourable
to the defendant, even if, contrary to my view, the answers to the first two
questions are favourable to the claimant. It also follows that, if the defendant
is correct on the first issue, as I have concluded, then it also succeeds
on the second issue.
- What if the claimant is right on the first issue, and "one or more surfactants" in Claim 1(a) is a reference to any material which adsorbs onto the surface of particles of another material (in this case propanil) and, as a result, keeps the particles apart during the milling stage? In that event, a question, essentially one of fact, has to be determined, namely whether Paselli and/or China Clay do so adsorb, and keep the propanil particles apart during the milling. In this connection, it is important to bear in mind that, as I have already mentioned, flow aids of a particulate nature, which do not act by adsorption onto the surface of, in this case, propanil were well known as at the priority date. Accordingly, the question whether Paselli and/or China Clay work by adsorption, that is by making use of an energetic surface interaction with the propanil, is the central issue for this purpose.
- The evidence relating to the action of Paselli and China Clay if and when added to propanil at the mixing stage (i.e. at the equivalent of the first step) was not very satisfactory, as both parties and their respective experts appear to agree. Thus, in order to reach a reasonably confident conclusion, considerably more research would have to be done than has been carried out so far.
- So far as Paselli is concerned, Professor Ryan said that he would expect propanil to form H-bonded complexes with Paselli, which would be driven by the reduction in surface energies associated with the formation of such bonds. He said that, if that was right, Paselli would be acting as a surfactant (at least on the claimant's interpretation of that expression). He had carried out experiments with Paselli in an aqueous system, but the results were such that he frankly said that they provided no assistance for his view on the point. Professor Luckham expressed "serious doubt" whether Paselli would act in the way described by Professor Ryan in aqueous solution. As I understood him, he went on to explain that if Paselli was unlikely to act as a surfactant in an aqueous phase, it was even less likely to act as a surfactant in a dry, anhydrous phase, such as is involved in air milling. This was essentially based on the fact that the H-bond mentioned by Professor Ryan represented short-range interactions. He went on to explain:
- Professor Luckham also explained that the roughness and thickness of particles would mean that they only touch each other in a few places, and that that would further reduce the prospect of any H-bond formation. He also took the view that, because of its low vapour pressure, individual molecules of Paselli would be unlikely to be able sufficiently to detach themselves from a solid Paselli particle and attach onto, or be adsorbed onto, a propanil particle, to any significant extent. Perhaps not surprisingly, Professor Luckham considered that Professor Ryan's limited tests on the performance of Paselli in an aqueous system assisted his view, and he went into a little detail to explain why.
- If the evidence had stopped there, I would have held that the defendant had established that Paselli did not act as a surfactant (even on the claimant's definition) at the milling stage. The claimant, however, relied on the proposition that, at the milling stage, propanil is likely to be molten, and that, in those circumstances, particles of Paselli would adhere to the surface of the propanil, as Professor Luckham accepted. I did not find the evidence of Professor Luckham in cross-examination on that issue entirely easy to follow; that is not meant as a criticism either of him or of Mr Carr, who cross-examined him. It was largely due, I think, to the fact that Professor Luckham was answering questions on the basis that "surfactant" meant something different from that which he believed, and on the basis of the assumption, of which he did not know, that the propanil was molten. Nonetheless, it seems to me that the effect of his evidence was that, in agreement with Professor Ryan, (a) if the propanil was molten at the milling stage and (b) if the term "surfactant" had the meaning contended for by the claimant, then Paselli would act as a surfactant. Accordingly and (in light of the weak nature of the evidence on the point) unfortunately, the issue resolves itself into the question of whether the propanil becomes molten during milling.
- There is obvious force in Mr Floyd's contention that there is no evidence that propanil would be molten during the milling process, particularly as the suggestion comes from the claimant, whose only directly relevant witness, Professor Ryan, has never inspected inside a mill. However, the teaching of the patent in suit, whose validity I am assuming for the purpose of this preliminary issue, does suggest that propanil becomes "sticky" when being milled. It is clear that milling must increase the temperature of the surface of the propanil particles, and that propanil has a comparatively low melting point. Bearing in mind my conclusion on the burden of proof, I have, with real diffidence, reached the conclusion that Paselli would act as a surfactant at the milling stage because, but only because, the propanil would be sticky, as two passages in the patent in suit suggest.
- I turn, now, to China Clay. In that connection, the evidence of Professor Ryan and Professor Luckham was, respectively, very similar to that in relation to Paselli. Thus, Professor Ryan said that there would be "preferential adsorption of clay onto the propanil particle's surfaces". Professor Luckham identified the same problems with this view as he considered existed in relation to Paselli. He also said that if China Clay did attach to propanil by H-bonding, it would raise the surface energy of the propanil, whereas, in order to act as a surfactant, it should lower the surface energy. While accepting the result, Professor Ryan did not agree with the conclusion: he said that it was not a requirement of a surfactant that it lowered surface energy. I have seen nothing to suggest that, in order to be a surfactant, a substance must lower the energy of the surface onto which it is adsorbed, and, I accept Professor Ryan's view, in preference to that of Professor Luckham, on this limited issue.
- Some micro-photographs were put in by Professor Ryan; his view was that they supported the contention that clay acted as a surfactant (within the claimant's meaning of that word) at the milling process. It would be unfair on the defendant to give much weight to these photographs, bearing in mind that they were put in late, but they do tend to support the claimant's case with regard to China Clay. In particular, they tend to indicate that propanil particles may well be at least sticky, possibly molten, a point which, of course, is not only relevant for China Clay, but also for Paselli. It is true that, while the photographs suggest that there is some adhesion between China Clay and propanil particles, they do not show whether the China Clay is acting as a surfactant, even within the wider meaning of that term adopted by the claimant. However, there was a difference in the photographs between the way in which the China Clay and propanil particles adhered together before, and after, milling. Further, the cross examination of Professor Luckham indicated, at least to me, that if China Clay did adhere to an extent to the particles of propanil, it was acting as a surfactant, always assuming the wider meaning of that term as adopted by the claimant.
- In the result,
while, as Mr Floyd rightly said, the evidence on this aspect of the case particularly
unsatisfactory, I have reached the conclusion that, if, contrary to my view,
the claimant is right on the first issue, it succeeds on the second issue.
It is right to add that I might well have reached a different conclusion on
this issue if the burden of proof were on the claimant.
- In these circumstances, I conclude the preliminary issue in favour of the defendant. On the basis that the reference to "one or more surfactants" in Claim 1(a) of the patent in suit is to one or more amphiphiles, as I believe to be correct, Process B does not infringe. If I am wrong and "surfactants" has the wider meaning contended for by the claimant, then I would have concluded, with some diffidence, that Process B does infringe. Subject to further argument, I think that it follows that the defendant is entitled to a declaration that Process B does not infringe the patent in suit.
Whether Process B comprises the step of combining one or more surfactants with propanil and milling to particle size of less than 20 microns to form a premix; and if not
Whether by reason of the absence of the said step, the use of Process B (and accordingly any dispersible granules produced by such process) does not infringe any claim of the patent in suit.
TECHNICAL BACKGROUND
THE PATENT IN SUIT
"In attempts at making pesticide granules, it has often been found that granules or agglomerates prepared from the formulated wettable powders of the art using well-known agglomerating techniques and using water as the agglomerating agent, are not easily dispersible in water. On the other hand, agglomerates which are readily water-dispersible are often not sufficiently resistant to attrition and form a fine dust fraction upon handling and shipping. If conventional binders are added to make the granules strong, then they are not dispersible in water. [Certain techniques which have already been discovered] have also been used to form granules containing up to 50% of active pesticide, but the resulting granules are not rapidly or completely water dispersible and are not suitable for use in preparing sprayable suspensions."
"A ... herbicide composition designed for dispersion in a liquid carrier should ideally have a high content of active material, should be readily dispersible in the carrier, and should then form a dispersion which is as stable as possible, requiring the minimum of subsequent agitation for homogeneity. The liquid carrier will, of course, for convenience normally be water."
"Low-melting solids such as propanil present an especially difficult problem in the preparation of a dispersible granule formulation. The low-melting solid, herein defined as melting below 100º C, tends to melt or become sticky during or subsequent to the grinding process which is a necessary step in preparing dispersible granules. [An earlier patent] requires micro-encapsulation [which] involved additional pressing steps and adds to the cost of the overall formulation."
"[An earlier patent] discloses a process for the preparation of water dispersible granules comprising admixing the desired ingredients of the granules into an extrudable form, extruding the mix and then rolling the extrusions and optionally drying the extrusions. The desired ingredients may comprise propanil.
In the case of the herbicide propanil, it has not heretofore been possible to produce a dispersible granular product which combines the features of a high active ingredient content and good suspensibility and dispersant properties, as well as resistance to attrition - thereby avoiding the formation of a dust."
"We have now discovered a process for producing dispersible granule formulations of propanil herbicide. The process can provide granules which contain more than 60% active ingredient, which also have good suspensibility and dispersability characteristics, and which resist attrition."
"In addition to the active ingredient, propanil, the mixture to be formed into dispersible granules contains one or more surfactants and, optionally, flow enhancing agents, dispersants, wetting agents and defoaming agents".
"The term "surfactant" is used in the broad sense, to include materials which may be referred to as emulsifying agents, dispersing agents and wetting agents, and the surfactant component may comprise one or more surfactants selected from the anionic, cationic and non-ionic type".
"In the context of this specification a dispersing agent is a surfactant which facilitates the dispersion of the pesticide particles when the product is added to a liquid, for example water."
Examples of surfactants which are wetting agents are given at lines 47-49.
"All surfactants act as dispersing agents to some degree, and also to some degree as wetting agents ...".
"Small particles of a low-melting solid such as propanil often stick together thereby causing flow problems in processing the material. Flow aids such as clays or silica particles may be used to minimize these problems. Flow aids preferred for the propanil dispersible granule include [certain specified proprietary brands]. The flow aid content of the dispersible granule may vary from 0 to 10%...."
"Disintegrants, which are water soluble, organic compounds such as starch or sugar or inorganic salts such as sodium acetate or sodium bicarbonate, are sometimes used in dispersible granule formations. ... We have found these disintegrants have adverse effects on the propanil dispersible granules prepared according to this invention. ... Consequently, granules prepared according to the present invention are preferably substantially free of disintegrants."
"Dust content and resistance to attrition of the propanil dispersible granules prepared according to this invention are minimised by forming the granules by the preferred mode of extrusion".
"Process for producing a dispersible propanil granule comprising:
a) combining one ore more surfactants with propanil and milling to a particle size of less than 20 microns to form a pre-mix;
b) adding less than 25 per cent by weight water and optionally a wetting agent to the said pre-mix and mixing until a paste is obtained;
c) granulating said paste thereby producing granules; and
d) drying said granules to a moisture content of less than 2 per cent by weight."
"4. Process according to any preceding claim wherein one or more of a dispersant, a flow aid and a defoaming agent are added during step (b).
5. Process according to any preceding claim comprising the steps of:
a) milling a mixture of propanil dispersant and flow aid to a particle size between 3 and 15 microns;
b) adding a wetting agent dissolved in 12-20 per cent by weight water to the milled mixture of step (a) and mixing until a homogeneous, extrudable paste is obtained;
c) extruding said paste to form granules; and
d) drying said extruded granules ...
...
10. A dispersible granule according to any one of claims 6 to 9 [which by virtue of claim 6 includes claims 1 to 5] which is substantially free of disintegrant."
THE ISSUES BETWEEN THE PARTIES
THE BURDEN OF PROOF
"The burden of proving the absence of infringement rests, in my judgment, upon the plaintiff. If there be a lack of clarity or precision, the court is not in a position to grant the declaration sought."
PRINCIPLES OF CONSTRUCTION AND THE EXPERT EVIDENCE
The approach to construction
"Purposive construction, namely the ascertainment of meaning having regard to the purpose of the words. The close analysis of the words in the specification carried out by the parties amounted to the literal analysis which had been rejected as wrong."
"(1) Does the variant have a material effect upon the way the invention works? If yes, the variant is outside the claim. If no-
(2) Would this (i.e. that the variant had no material effect) have been obvious at the date of publication of the patent to a reader skilled in the art. If no, the variant is outside the claim. If yes-
(3) Would the reader skilled in the art nevertheless have understood from the language of the claim that the patentee intended that strict compliance with the primary meaning was an essential requirement of the invention. If yes, the variant is outside the claim."
The addressee of the patent in suit
"There is no basis in law or in logic for including within the concept of "a person skilled in the art" a person who is not directly involved in producing the product described in the patent or in carrying out the process of production."
THE FIRST ISSUE: THE MEANING OF "SURFACTANT" IN THE PATENT IN SUIT
Introduction
The reason for adding one or more surfactant: the claimant's explanation
"Dispersing agents are substances which absorb onto the surface of particles in aqueous media and helped to preserve the state of dispersion of the particles preventing them from reaggregating. ....Again it is clear to me from the patent that the intention of [the draftsman] was to use the term dispersing agents in this way."
"I agree that surfactants are needed for the purpose of enabling wetting of the milled propanil and to disperse the final product when it is added to water. These surfactants which function as wetting and dispersing agents must be amphiphiles."
"In the context of this specification a dispersing agent is a surfactant which facilitates the dispersion of the pesticide particles when the product is added to a liquid, for example water."
"Reasonable people in this art may differ about whether types of dispersants are to be regarded as surfactants?
In the surfactant art, yes, but not in the agrochemical art.
...
Are you suggesting that dispersant has a special meaning in the agrochemical industry?
No. I am suggesting that it [means] something a bit different in the ceramics industry. ...
People in the ceramics industry would not regard a dispersant as a surfactant because they are not amphiphiles, whereas people in the agrochemical industry... would, because there the materials they are using for dispersants are amphiphiles."
There was also reference to titania particles which stabilised so-called Pickering emulsions: that was not concerned with dispersing solid pesticides, but with stabilising existing dispersions.
The reason for adding one or more surfactant: the defendant's explanation
"From my experience, the purpose of what is taught in the patent, that is mixing and grinding the surfactants with the active ingredient in a dry grinding process is to ensure that a completely homogenous dry mixture has been obtained. Thus when water is added prior to extrusion the surfactants are in intimate contact with active ingredient particles and can prevent agglomeration of particles during extrusion and drying. Both the wetting agent and the dispersing agent are often added to the powder pre-mix before dry milling for this reason."
The specification: other indications
"The term "surfactant" is used in the broad sense to include materials which may be referred to as emulsifying agents, dispersing agents and wetting agents and the surfactant component may comprise one or more surfactants selected from the anionic cationic and non-ionic type."
"All surfactants act as dispersing agents to some degree and also to some degree as wetting agents."
Other cited references to surfactants
"A surfactant or surface-active agent is a species that is active at the interface between two phases, such as the interface between hydrophilic and hydrophobic phases. A surfactant accumulates at the interface and modifies the surface tension."
"Every surfactant possesses the fundamental characteristic of having two essential portions, one being water repellent, usually called hydrophobic (or lipophilic), the other being hydrophilic (lipophobic)."
The other Claims
The expert evidence
Conclusion on the first issue
THE SECOND ISSUE: DOES PROCESS B INFRINGE THE PATENT IN SUIT?
Introductory
If the defendant is right on the first issue
If the claimant is right on the first issue
"In the solid state the molecules are severely hindered in their motion [and] there is no way that sufficient numbers of H-bonds could form to hold the Paselli on the surface of the propanil."
CONCLUSION
© 2000 Crown Copyright