T 1182/01 14-06-2005

I. The grant of the European patent No. 0 584 771 in the name of The B.F. Goodrich Company (later Noveon IP Holdings Corp.) in respect of European patent application No. 93 113 458.9 filed on 24 August 1993 and claiming priority of the US patent application No. 935616 filed on 26 August 1992 was announced on 29 December 1997 (Bulletin 1997/52) on the basis of 35 claims.

Independent Claims 1 and 20 read, respectively, as follows:

"1. An interpolymer of

(1) at least one olefinically unsaturated carboxylic acid or anhydride containing at least one activated carbon-to-carbon olefinic double bond and at least one carboxyl group, in an amount of at least 15% by weight based upon the weight of the interpolymer, and

(2) 0.001 to 20% by weight based upon the weight of said carboxylic acid or said anhydride of at least one steric stabilizer having at least one hydrophilic moiety and at least one hydrophobic moiety, selected from the group consisting of - linear block copolymeric steric stabilizers, having a hydrophobic moiety having a length of more than 5 nm (50 Angstroms) (as calculated by the Law of Cosines) and being defined by the following formula:

Cw (-B-A-By-)xDz

wherein A is a hydrophilic moiety having a solubility in water at 25°C of 1% or greater, a molecular weight of from 200 to 50,000, and selected to be covalently bonded to B;

B is a hydrophobic moiety having a molecular weight of from 300 to 60,000, a solubility of less than 1% in water at 25°C, capable of being covalently bonded to A;

C and D are terminating groups which can be A or B, can be the same or different groups,

w is 0 or 1;

x is an integer of 1 or more,

y is 0 or 1, and

z is 0 or 1,

- random copolymeric comb steric stabilizers, being defined by the following formula:

R1-(Z)m-(Q)n-R2

where R1 and R2 are terminating groups and may be the same or different and will be different from

Z and Q,

Z is a hydrophobic moiety having a solubility of less than 1% in water at 25°C,

Q is a hydrophilic moiety, having a solubility of more than 1% in water at 25°C, and

m and n are integers of 1 or more, and are selected such that the molecular weight is from 100 to 250,000, and

- mixtures thereof.

20. A method of interpolymerizing at least one olefinically unsaturated carboxylic acid or anhydride monomer containing at least one activated carbon-to-carbon olefinic double bond and at least one carboxyl group, and 0.001 to 20 weight percent, based upon the weight of said carboxylic acid or said anhydride, of at least steric stabilizer having at least one hydrophilic moiety and at least one hydrophobic moiety and selected from the group consisting of:

- linear block copolymeric steric stabilizers having a hydrophobic moiety having a length of more than 5 nm (50 Angstroms) (as calculated by the Law of Cosines) and being defined by the following formula:

Cw (-B-A-By-)xDz

wherein A is a hydrophilic moiety having a solubility in water at 25°C of 1% or greater, a molecular weight of from 200 to 50,000, and selected to be covalently bonded to B;

B is a hydrophobic moiety having a molecular weight of from 300 to 60,000, a solubility of less than 1% in water at 25°C, capable of being covalently bonded to A;

C and D are terminating groups which can be A or B, can be the same or different groups,

w is 0 or 1;

x is an integer of 1 or more,

y is 0 or 1, and

z is 0 or 1,

- random copolymeric comb steric stabilizers being defined by the following formula:

R1-(Z)m-(Q)n-R2

where R1 and R2 are terminating groups and may be the same or different and will be different from Z and Q,

Z is a hydrophobic moiety having a solubility of less than 1% in water at 25°C,

Q is a hydrophilic moiety, having a solubility of more than 1% in water at 25°C, and

m and n are integers of 1 or more, and are selected such that the molecular weight is from 100 to 250,000 and mixtures thereof, in an organic media consisting essentially of organic liquids, in the presence of free radical forming catalysts, wherein said carboxylic acid or anhydride is present in an amount of at least 15% by weight based upon the weight of the interpolymer."

II. On 24 September 1998 a Notice of Opposition was filed by BASF AG in which revocation of the patent in its entirety was requested on the grounds of lack of novelty and lack of inventive step (Article 100(a) EPC) and insufficiency of disclosure (Article 100(b) EPC).

These objections were supported, inter alia, by the following documents:

D1: EP-A-0 297 184;

D2: EP-B-0 178 127; and

D3: EP-A-0 126 528.

III. By a decision announced orally on 16 May 2001 and issued in writing on 23 August 2001, the Opposition Division rejected the opposition.

IV. In its decision, the Opposition Division held that the requirements of Article 83 EPC were met, since the skilled person following the information given in the examples of the patent in suit patent in suit, and perhaps making a few routine experiments should have found the appropriate amounts of starting monomers in order to carry out the process of Claim 20.

Before dealing with the further objections of lack of novelty and lack of inventive step, the Opposition Division held that the term "interpolymer" used in the claims should be interpreted as referring to any association of a carboxylic acid polymer and a steric stabilizing surfactant. It further held that it was clear from the wording of Claim 1 that the interpolymer must contain at least 15% by weight of a carboxylic acid or anhydride, and that a polymer comprising only the salt of a carboxylic acid would not meet the former requirement and would not be within the scope of Claim 1 of the patent in suit.

Concerning novelty, the Opposition Division stated that none of the documents D1, D2 (even taking the reference in D2 to Example 3 of document EP-A-0 077 618 (referred to below as D12) into consideration) and D3 disclosed an interpolymer containing at least 15% by weight of a carboxylic acid or anhydride and an amount of steric stabilizer of 0.001 to 20% by weight based on the weight of said carboxylic acid or said anhydride.

Concerning inventive step, the Opposition Division stated that, as disclosed in the patent in suit, thickeners on the basis of olefinically unsaturated carboxylic acid or anhydrides obtained via solution/precipitation were known in the art. Starting from this prior art, the technical problem was seen as to provide a polymer which was easy to disperse and yielded lower dispersion viscosities combined with increased thickening properties.

According to the decision of the Opposition Division, documents D1 to D3 were concerned with a technical problem unrelated with the one underlying the opposed patent, so that they could neither serve as a valid starting point nor render obvious the subject-matter of the patent.

V. A Notice of Appeal was filed on 31 October 2001 by the Appellant (Opponent). The prescribed fee was paid on the same day.

With the Statement of Grounds of Appeal filed on 21. December 2001, the Appellant submitted the following documents:

D4: EP-A-0 333 499;

D5: US-A-4 419 502;

D6: EP-A-0 412 388;

D7: US-A-4 529 773;

D8: EP-A-0 522 467;

D9: EP-A-0 151 467;

D10: EP-A-0 172 025;

D11: US-A-4 892 916, and

D12: EP-A-0 077 618.

It also argued essentially as follows

(i) Concerning novelty:

(i.1) The term "carboxylic acid" used in the patent in suit should be interpreted as encompassing free carboxylic acid and salts thereof.

(i.2) The amount of steric stabilizer should be calculated on the total amount of carboxylic acid in interpolymer, i.e. the amount of free and neutralized acid and was independent on the amount of free acid in the interpolymer.

(i.3) Thus, D1, D2 and D3 destroyed the novelty of the subject-matter of the patent in suit.

(i.4) Even if one would consider that the term "carboxylic acid" referred only to free carboxylic acid, documents D2 and D3 would also be a novelty destroying documents.

(i.5) Documents D4 to D11 were also novelty destroying for the subject-matter of the patent in suit, since they disclosed either a composition comprising a polymer of an unsaturated carboxylic acid with an emulsifier falling under the definition of the steric stabilizer according to the patent in suit (D4, D5, D6, D8, and D10) or a copolymer of an unsaturated carboxylic acid with a comonomer falling under the definition of the steric stabilizer (D7, D9 and D11).

(ii) Concerning inventive step:

(ii.1) Contrary to the submissions of the Opposition Division, D3 would represent the closest state of the art.

(ii.3) According to the decision of the Opposition Division, the technical problem to be solved by the patent in suit was to provide thickeners which were easy to disperse and which exhibited good thickening properties.

(ii.4) The solution proposed in the patent in suit was to prepare an interpolymer according to Claim 1 in non neutralized form. This polymer could be easily dispersed in water with the other components of the dispersion, and could, after addition of a base, thicken the mixture.

(ii.5) The technical problem solved by D3 was to provide polymers which were easy to disperse and which could be used as thickener.

(ii.6) The skilled person would determine which amount of free carboxylic groups would be necessary to obtain a good thickening effect after the addition of a base.

(ii.7) Furthermore, D10 clearly taught to add the base after the mixture of the thickener with the other components of the dispersion had been completed.

(ii.8) Thus, the subject-matter of the patent in suit would lack inventive in view of D3 alone or in view of the combination of D3 with D10.

(ii.9) D4 could also be taken as the closest state of the art, since it disclosed polymers exhibiting all the features set out in Claim 1 in terms of amount of unsaturated carboxylic acid in the interpolymer, type of steric stabilizer and amount thereof.

(ii.10) D4 alone or in combination with D10 would render the claimed subject-matter obvious.

VI. In its letter dated 11 September 2002, the Respondent (Patent Proprietor) argued essentially as follows:

(i) By submitting the new documents, the Appellant had filed a new opposition.

(ii) No reasons had been submitted by the Appellant for the late submission of these documents.

(iii) These documents could have been filed within the opposition time limit. Their unsubstantiated late filing 39 months after the time limit for filing the opposition amounted to a procedural abuse.

The Respondent thus requested remittal of the case back to the first instance, and apportionment of 100% of the costs involved on the side of the Respondent which occurred in conjunction with the late filing of these documents.

VII. In its letter dated 8 October 2002, the Appellant argued essentially as follows:

(i) Documents D4 to D10 were introduced as a reaction to the decision of the Opposition Division, to consider the subject matter of the patent in suit as novel and inventive over D1 to D3.

(ii) Documents D4 to D10 were prima facie relevant for the patentability of the patent in suit.

(iii) The Patentee had not taken position on the relevance of the new documents. He had not submitted further arguments why these documents should be considered as late.

(iv) Thus, the requests of the Patentee for remittal and apportionment of costs should be dismissed.

VIII. The submissions of the Respondent in its letter dated 10. June 2003 might be summarized as follows:

(i) There was no obligation to indicate reasons why the submissions of the numerous new prior art by the Appellant should be considered as late.

(ii) The opposition procedure had not been conducted by the Appellant with the necessary diligence.

(iii) These late submissions represented an abuse of the proceedings.

IX. With its letter dated 21 June 2004, the Respondent filed 6 auxiliary requests. It also submitted an experimental report and a document referred to as

D13: Morrison and Boyd, "Organic Chemistry", 3rd Edition, July 1976; page 579.

It also argued essentially as follows:

(i) As shown in D13, carboxylic acid were defined by the structural element -COOH. Thus, salts of carboxylic acids should be distinguished from carboxylic acids.

(ii) It thus followed that the amount of stabilizer was dependent on the amount of olefinic unsaturated acid or anhydride.

(iii) Concerning documents D1 to D3:

(iii.1) D1, D2 and D3 disclosed polymers containing the carboxylic acid in neutralized form.

(iii.2) The polymers according to D1 to D3 had been obtained according to the reverse phase emulsion. This process required that the carboxylic groups were neutralized.

(iii.3) No evidence had been provided by the Appellant that producing a polymer according to D1, D2 and D3 directly an unavoidably led to a polymer having the amount of carboxylic acid groups as required in the patent in suit.

(iii.4) Thus, the claimed polymer was novel over D1 to D3.

(iii.5) Claim 1 of the first auxiliary request was drafted in a product-by-process form. This further underlined that the carboxylic acid was not in neutralized form and was polymerized in an organic medium. The subject-matter of Claim 1 was thus clearly distinguished from the cited prior art.

(iii.6) The person skilled in the art would have no motivation from D1 to D3 to solve the problem of providing an easy to disperse, easy to handle well thickening polymer as proposed by the patent in suit.

(iii.6.1) D1 was concerned by ionic polymers, in which the acid groups had been neutralized.

(iii.6.2) D2 was not directed to the provision of thickeners.

(iii.6.3) D3 related to dispersion of water swellable polymers in a water immiscible liquid with reduced amounts of emulsifiers. It did not belong to the same technical field as the patent in suit.

(iv) Concerning the auxiliary requests 2 to 6

(iv.1) In Claims 1 of the 2nd and 3rd auxiliary requests the definition of the block copolymer steric stabilizer had been limited to a BAB block copolymer and the interpolymer further comprised a polyether crosslinking agent.

(iv.2) Claims of the 4th auxiliary request corresponded to method claims 20 to 35 as granted. Claims of the 5th auxiliary request corresponded to method claims 18 to 32 of the 2nd auxiliary request. Claims of the 6th auxiliary request corresponded to method claims 17 to 30 of the 3rd auxiliary request.

(iv.3) Documents D1 to D4, and D6, D7, D9 to D12 did not disclose a polyether crosslinking agent.

(iv.4) D5 to D9 and D11 and D12 were silent on the presence of a BAB stabilizer.

(iv.5) D1 to D3 and D6 to D12 related to reversed phase polymerization. Thus, the carboxylic acid groups of the polymer would be neutralized.

(iv.6) Thus, the subject-matter of these auxiliary requests was novel over the cited prior art.

(iv.7) Concerning inventive step:

(iv.7.1) References D6 to D11 were not more relevant than D1 to D3.

(iv.7.2) It had been further shown by the examples of the patent in suit that the use of the specific BAB steric stabilizer led to an improved balance between unneutralized dispersion viscosity and neutralized dispersion viscosity.

(iv.7.3) The experimental report showed that the use of a polyether crosslinking agent instead of those disclosed in D4 led to better ability to build viscosity, better salt sensitivity, and better dispersability. It also showed that the use of BAB block copolymers instead of AB polymers disclosed in D5 led to lower dispersion viscosity with comparable dispersion times.

X. Oral proceedings before the board were held on 14 June 2005.

At the oral proceedings the discussion focussed on (i) the question as to whether there was a justification for the late filing of the documents D4 to D11, and (ii) on the question of the admission of documents D4 to D11 into the proceedings.

The arguments presented by the Parties concerning these points may be summarized as follows:

Concerning point (i):

(i.1) By the Appellant:

(i.1.1) In view of their high relevance, documents D4 to D11 should be not considered as late filed.

(i.1.2) In view of page 4, lines 45 to 46 of the patent in suit which stated that "the carboxylic monomers are the olefinically-unsaturated carboxylic acids containing at least one activated carbon-to-carbon olefinic double bond, and at least one carboxyl group; that is, an acid or function readily converted to an acid containing an olefinic double bond", it was the Opponent's view that the term "carboxylic acid" would also encompass the salts thereof.

(i.1.3) On that basis, there had been no reason for the Appellant to submit further documents in addition to D1 to D3, since, in the Appellant's view, these documents were clearly novelty destroying for the claimed subject-matter.

(i.1.4) The Appellant was hence surprised by the restrictive interpretation given by the Opposition Division to the term "carboxylic acid", i.e. referring only to free acid.

(i.1.5) The Appellant was further surprised by the interpretation given by the Opposition Division to document D2, according to which the acrylic acid was neutralized before polymerization.

(i.1.6) For these reasons a new search had become necessary and documents D4 to D11 must be seen as a reaction to the interpretations made by the Opposition Division of the term "carboxylic acid" and of document D2.

(i.1.7) According to the decision under appeal, documents D1 to D3 referred to reverse phase emulsion polymerization while, according to the patent in suit, the polymers had been obtained by a solution/ precipitation polymerization.

(i.1.8) Documents D4 to D11 had been cited to show that polymers according to the patent suit were known in the art and have been prepared by a process other than reverse phase emulsion polymerization. They further showed that monomers with free acid groups could be used in that latter process and that interpolymers prepared by this process and falling under the scope of the patent in suit were known in the art.

(i.2) By the Respondent:

(i.2.1) From page 4, line 53 of the patent in suit it was evident that the term carboxylic acid referred to the free acid and anhydride thereof.

(i.2.2) In view of the teaching of the patent in suit, it was further clear that the salts of the carboxylic were not encompassed by the term "carboxylic acid", since the claimed polymers needed to be neutralized when used as thickeners, i.e. their thickening activity was linked to their possibility to be neutralized.

(i.2.3) Thus, there was no justification for the late filing of documents D4 to D11, which could indeed have been cited during the opposition period.

Concerning point (ii):

(ii.1) While relying essentially on its written submissions, the Appellant made the following additional statements:

(ii.1.1) Documents D4 and D5 disclosed the preparation of an interpolymer by a solution polymerization process.

(ii.1.2) It was clear that the pertinence of documents D4 and D5 had been recognized by the Patentee in view of its submissions made in its letter dated 21 June 2004.

(ii.1.3) Example 3 of D4 was particularly pertinent. It was contested that the process used in this example was a reverse phase emulsion polymerization. In any case, Claim 1 of the patent in suit was directed to a polymer per se.

(ii.1.4) Documents D7 and D11 disclosed the use of interpolymers of (meth)acrylic acid with a stabilizer of type AB as thickeners. The thickening effect was achieved by neutralization of the free acid groups.

(ii.1.5) D9 disclosed the manufacture of an interpolymer of unsaturated carboxylic acid with a stabilizer of type AB. They could be obtained by solution polymerization. The thickening activity of the interpolymers of D9 was achieved by the neutralization of the free acid groups of the interpolymer.

(ii.1.6) In Example 2 of D10, the acrylic acid was not completely neutralized. The amount of AB stabilizer in this example corresponded to the amount of stabilizer required by the patent in suit.

(ii.2) The Respondent indicated that it had no comments to make on documents D5, D7, D9, and D11 and made, in substance, the following submissions concerning the further documents:

(ii.2.1) In Example 3 of D4 the polymer was obtained by the reverse phase emulsion polymerization.

(ii.2.2) Reverse phase emulsion polymerization was also used in the preparation of the copolymers disclosed in documents D6, D8 and D10. This process required the neutralization of the acid groups. This was also evident from the examples of D6, D8, and D10.

(ii.2.3) The amount of stabilizer in Example 2 of D10 was well above the amount required by the patent in suit.

XI. The Appellant requested that the decision under appeal be set aside and that the European patent No. 584 771 be revoked, that the request of the respondent for an apportionment of costs should be rejected and that the Board should decide on the outstanding issues without remittal to the first instance.

The Respondent requested that the appeal be dismissed or in the alternative that the patent be maintained on the basis of one of the six auxiliary requests, filed with the letter dated 21 June 2004 or that the case be remitted back to the first instance for further prosecution. Further the Respondent requested that 100% of the costs involved on the side of the patentee and his representative which occurred in conjunction with the late submissions of documents be apportioned.