T 0946/04 02-03-2006

1. The appeal is admissible.

2. Procedural matters

2.1 As mentioned in Section VII above, the Appellant was absent from the oral proceedings held on 2 March 2006.

2.2 At the oral proceedings the Board established that the Appellant had been duly summoned in accordance with the requirements of Rule 71(1) EPC and that its unexpected absence was not due to any unforeseen circumstances but to its decision, not communicated to the Board beforehand, not to attend the oral proceedings. Therefore, the oral proceedings continued in its absence (Rule 71(2) EPC).

2.3 It further follows, that, in accordance with Article 11(3) of the Rules of Procedure of the Boards of Appeal, the Board considers that the absent party relies only on its written case.

3. Novelty

3.1 Concerning novelty, the only issue to be decided is whether the prior sale of the product PSX-700 by Ameron International Corporation deprives the subject-matter of any of Claims 1 to 25 of the patent in suit of novelty.

3.2 According to the decision of the Enlarged Board of Appeal G 1/92 (OJ EPO 1993, 277), "where it is possible for the skilled person to discover the composition or the internal structure of the product and to reproduce it without undue burden, then both the product and its composition or internal structure become state of the art." (Reasons 1.4).

3.3 In this connection, the Board observes that, according to the declaration of Mr. Foscante dated 30 May 1996 (Appendix A), the composition of the product PSX-700 corresponds to the composition of Example 1 of the document D1, which is the US patent application corresponding to the patent in suit, and that the composition according to Example 1 of D1 exactly corresponds to the composition of Example 1 of the patent in suit.

3.4 In view of Example 1 of the patent in suit, it is thus clear that the PSX-700 comprises two components, i.e. a resin component comprising for a total of 1200 g:

385 g of Eponex 1513 (a non aromatic epoxy resin);

5 g of Nuosperse 657 (a pigment wetting agent);

5 g of BYK 080 (an antifoam agent)

10 g of Dislon 6500 (a thixotropic agent)

338 g of Tioxide RTC60 (titanium dioxide)

25 g of A-163 (methyl trimethoxysilane)

432 g of DC 3074 (a methoxy functional polysiloxane); i.e. in total 1200 g.

and a curing component comprising for 300 g of the resin component:

48 g A-1100 (aminopropyl) trimethoxysilane 20 g butyl acetate.

3.5 It is further clear that the resin component and the curing component are obtained by simple mixing of the respective ingredients.

3.6 It can hence be concluded that, provided the ingredients of both the resin component and the curing component could be known to the skilled person, there would be no difficulty for him to reproduce the product PSX-700.

3.7 Consequently, the second requirement set out in decision G 1/92 in terms of reproducibility would, in the present case, inevitably be fulfilled, provided the first requirement in terms of analysability would be met.

3.8 In that respect, while the Appellant has submitted in view of the decision T 952/92 (cf. Headnote point IV) that a complete analysis of the sold product would not be necessary, the Board however notes that the circumstances of the present case totally differ from those underlying the decision T 952/92 for the following reasons:

3.8.1 In the case under consideration in T 952/92, the claimed product was a liquid homogeneous mixture for use in liquid scintillation technique, which does not undergo chemical reaction during its use. In contrast, the compositions according to the patent in suit are reactive products comprising two kinds of polymers, i.e. a polysiloxane and an epoxy resin which must exhibit very specific respective curing patterns in order to allow the formation of non-interpenetrating polymer network (non-IPN) structure (cf. also declaration of Mr. Foscante, point 19).

3.8.2 It hence clear that the ability of forming the non-IPN structure is directly linked to the choice of specific ingredients such as a specific polysiloxane, a specific epoxy resin, a specific organooxysilane, and a specific aminosilane in order to obtain the necessary curing profile of the epoxy resin and the polysiloxane leading to the formation of a non-IPN structure.

3.8.3 This has for its consequence that the result of the analysis of the product sold before the claimed priority date should also show, for example by way of comparison with compositions exemplified in the patent in suit, that this product when cured would inherently lead to the formation of a non-IPN structure. This can only be established provided the exact composition of the sold product can be determined, i.e. provided a complete analysis has been carried out.

3.8.4 This conclusion is also, in the Board's view, in line with the requirement set out in G 1/92 in term of reproducibility according to which the person skilled in the art is enabled to manufacture the product, i.e. the product actually sold before the relevant filing date (cf. G 1/92, paragraph 1.4), and with the decision T 472/92 (OJ EPO 1998, 161) according to which concerning the issue whether an invention has been made available to the public by prior use, it must be established exactly (emphases by the Board) what was in prior use.

3.9 Thus, in the Board's view, it would be the fact that direct and unambiguous access to the exact composition of the product PSX-700 would have been possible by means of analysis, which would render such composition available to the public and thus part of the state of the art for the purpose of Article 54(2) EPC.

3.10 Consequently, the question of novelty of the subject-matter of Claims 1 to 25 boils down to the question whether it has been shown by the Appellant (Opponent) that such analysis was possible in accordance with the known analytical techniques which were available for use by a skilled person before the relevant filing date, so as to inform such skilled person that the composition of PSX-700 was in fact in accordance with the invention claimed in the patent in suit.

3.11 In that respect, the Board firstly notes that it has been admitted by all the parties that the product PSX-700 was first released for sale in May 1994, i.e. before the claimed priority date of the patent in suit (18 November 1994). The Board also notes that the Appellant has in effect further admitted (cf. page 2, of the Statement of Grounds of Appeal) that no more modern equipment was available to the skilled person between the claimed priority date and the filing date in Europe (18 September 1995); in other words the analyzability of the product PSX-700 has not been modified in that intermediate period. Consequently, there is no necessity for the Board to investigate whether the priority claim is valid or not, since this question is, for the reasons given above, irrelevant to the assessment of novelty in view of the prior sale of the product PSX-700.

3.12 In this connection, the Board notes that analyses of the product PSX-700 have been carried out, on the one hand, by the Appellant in August 1995 (Evidence 12) and, on the other hand, by the laboratory TNO in May 2001 at the request of the Patent Proprietor (Evidence O). Although the respective dates of analysis are after the claimed priority date, there can be no doubt that the analytical methods used in these analyses were available before the claimed priority date, so that their evidential weight is not diminished by the fact that they have been carried out after that date.

3.13 According to Evidence 12, the analysis was performed using Fourier Transform Infrared Spectroscopy (FTIR) gas chromatography, gel permeation chromatography, and energy dispersive X-ray fluorescence spectroscopy. As indicated in Evidence 12 the infrared spectrum of the base (i.e. resin) component shows that the base consisted of a "mixture or a reaction product of phenyl methyl silicone and an aliphatic diglycidylether" and according to further investigation "it is probably a reaction product, but it has not been possible to identify the aliphatic diglycidylether."

3.14 Independently of the fact that the detailed laboratory data (Evidence 15, on which this analysis report Evidence 12 is based) only mentions the presence of an aliphatic glycidyl ether and not of a diglycidyl ether (emphasis by the Board) in view of the mono glycidyl ethers used as reference products in the IR spectroscopy (cf. page 2 of the letter of 23 February 2004, lines 4 to 24; IR Spectra 2D and 2E), it is in any case evident, in the Board's view, that the analysis carried out by the Appellant did not clearly and unambiguously reveal the presence of an epoxy resin, let alone of an epoxy resin having the chemical structure of the EPONEX 1513 used in the resin component of the product PSX-700.

3.15 The Board further observes that the analysis carried out by the Appellant in August 1995 (Evidence 12) did not even reveal either the presence of a methoxy polysiloxane or the presence of a methyl trimethoxysilane.

3.16 Consequently, the Board can only come to the conclusion that the actual analysis carried out by the Appellant in order to determine the composition of the PSX-700 product failed to reveal essential components thereof, i.e. a non aromatic epoxy resin having the chemical structure of EPONEX 1513, the methoxy polysiloxane, and the methyl trimethoxysilane. In other words, the analysis carried by the Appellant does not show that it was possible with analytical techniques which were available for use by a skilled person before the claimed priority date to determine the exact composition of the PSX-700 product, so as to inform the skilled person that the composition of PSX-700 was in accordance with the invention claimed in the patent in suit.

3.17 On the other hand, the analysis carried out by the laboratory TNO (cf. Evidence 0, Page 5, PSX-700 resin) did not identify the presence of an epoxy resin, let alone the presence of a non aromatic epoxy resin having the chemical structure of the EPONEX 1513, in the resin component of the PSX-700, although, as stated in the declaration of Mr. Maat of TNO of 5 April 2004 (Paragraphs 3, 6), he specifically looked for epoxide groups since there was a reference to "epoxy" in the documents (Evidence 1 to 7 and 13) submitted by the Patent Proprietor prior to conducting the analysis.

3.18 In this connection, the Board also notes that the expert of the Appellant (cf. Evidence 9; point 9.2) has confirmed not only that the tests carried out by TNO for trying to identify the presence of an epoxy resin in the resin component were suitable, but furthermore that the relevant tests in that respect have been performed by TNO.

3.19 Thus, the Board can only state that the analysis carried out on by TNO shows that it was not possible by known analytical techniques which were available for use by a skilled person before the relevant filing date to reveal the presence of a non aromatic epoxy resin having the chemical structure of the EPONEX 1513 in the resin component of PSX-700.

3.20 This conclusion cannot, in the Board's view, be altered by the further submissions made by the Appellant on the basis of Evidence 24, 25 and 26 in order to challenge the non detectability of the non aromatic resin in the product PSX-700.

3.21 According to the Appellant, Evidence 24 discloses that non aromatic epoxy resins i.e. EPONEX epoxy resins provide superior weatherability compared to aromatic epoxy resins. Hence, in view of this disclosure, the skilled artisan reading Evidence 26 where the weathering properties of PSX-700 coatings are advertised would understand that the PSX-700 coating contains a non aromatic epoxy resin of the EPONEX type. By simple IR spectroscopy as shown in Evidence 25, the skilled person would further ascertain that the PSX-700 indeed comprises a non aromatic epoxy resin of that type.

3.22 It is hence evident that the reasoning of the Appellant starting from Evidence 24 comprises the steps:

(i) firstly assuming that the PSX-700 contains a non aromatic epoxy resin and that this resin is a non aromatic resin as disclosed in Evidence 24, based on saturated bisphenol-A, i.e. an EPONEX type epoxy resin.

(ii) looking for confirmation of this assumption in Evidence 26 on the basis of the advertised weatherability of the PSX-700 product;

(iii) and further selecting the EPONEX 1510 among the non aromatic resins disclosed in Evidence 24, carrying out an IR analysis (spectrum 3b) as disclosed in Evidence 25 using EPONEX 1510 (spectrum 3b) as reference in order to ascertain the presence of an epoxy resin of the EPONEX type in the PSX-700 resin component.

3.23 In this connection, the Board, however, notes, that according to the patent in suit (cf. paragraph [0008] other types of non aromatic epoxy resin than EPONEX resins were at the disposal of the skilled person before the claimed priority date of the patent in suit.

3.23.1 Furthermore, Board also notes that, according to the declaration of Mr. Colin Hull dated 20 September 2005, in the last 20 years no coatings company had been able to commercialize a coating based on an EPONEX resin such as the EPONEX 1513 used in the product PSX-700.

3.24 Thus, there is, in the Board's view, no objective reason for immediately selecting Evidence 24 as starting point, so that this selection must therefore be considered as based on hindsight, i.e. on the knowledge derived from the patent in suit that the PSX-700 contains an epoxy resin of the EPONEX type, with the consequence that this vitiates ab initio the reasoning of the Appellant.

3.25 Even if for the sake of argument, one would consider that the reasoning of the Appellant had started from Evidence 26 instead of Evidence 24, it would also have suffered from the same deficiency for the following reasons:

3.26 While Evidence 26 describes PSX-700 as an epoxy/siloxane hybrid coating combining and enhancing the best characteristics of epoxies and aliphatic polyurethanes, it does not disclose, in the Board's view, clearly and unambiguously the use of an epoxy resin, let alone of a non aromatic epoxy resin, in the product PSX-700.

3.26.1 This is because the wording "epoxy" used in Evidence 26 cannot be considered as inevitably referring to an epoxy resin, since this term can also be understood as designating other chemical compounds having an epoxy group. This fact is also corroborated by the manner according to which the Appellant carried out its IR spectroscopy analyses on the PSX-700 product (cf. Evidence 15) for detecting the presence of epoxy compounds in it, while using mono glycidyl ethers (not epoxy resins) as references.

3.26.2 Nor could, in the Board's view, the indication of the good weatherability of the PSX-700 coatings in Evidence 26 be considered as an implicit unambiguous disclosure of the presence of a non aromatic epoxy resin in the PSX-700 product.

3.26.3 While it can be deduced from Evidence 24 that coatings on the basis of saturated bisphenol A epoxy resins (EPONEX type) would exhibit a good weatherability, this does not reciprocally imply that coatings containing an epoxy component and exhibiting good weatherability would inevitably be based on such non aromatic epoxy resin.

3.26.4 On the contrary, as shown by document D3, epoxy polymer/polysiloxane coatings comprising aromatic epoxy resins may also exhibit good weathering resistance (cf. D3, page 20, lines 10 to 12), so that the indication of good weathering properties of epoxy coatings cannot be inevitably equated with the presence of a non aromatic epoxy resin, let alone a non aromatic epoxy resin as disclosed in Evidence 24.

3.26.5 Furthermore, the Board also observes that the PSX-700 coating is said in Evidence 26 to have superior corrosion resistance in combination with good weathering properties, while as indicated in the patent in suit (Paragraph [0008]), non aromatic epoxy resins are generally known to have inferior corrosion resistance. Consequently, the alleged indication of the presence of a non aromatic epoxy resin in relation with good weathering properties in Evidence 26 would be clouded by the reference to superior corrosion resistance in the same document.

3.27 It thus follows from the above that it cannot be deduced from Evidence 26, even read in combination with Evidence 24, that the PSX-700 product comprises a non aromatic epoxy resin, let alone a non aromatic epoxy resin having the chemical composition of the EPONEX 1513.

3.28 Under these circumstances, there is no need for the Board to carry out a detailed evaluation of Evidence 25, since the alleged detectability of a non aromatic epoxy resin in the PSX-700 by attribution of some IR absorption bands in the IR spectrum 3b of Evidence 25 to the presence of an EPONEX resin in PSX-700 by way of comparison with the IR spectrum of the EPONEX 1510 raw material can only be based, for the reasons given above, on knowledge derived from the patent in suit.

3.29 Nor could the theoretical considerations made by the expert of the Appellant (cf. Evidence 11), in the Board's view, provide evidence that it would have been possible to detect the presence of the non aromatic epoxy resin having the chemical structure of EPONEX 1513 in the resin component of the PSX-700 by known analytical methods before the claimed priority date.

3.29.1 In this connection, the Board observes as a preliminary remark that the expert of the Appellant was already aware of the composition of the PSX-700 when he made its submissions, since its consultancy report referred to the "Opposition against European Patent Application Number 0792314".

3.29.2 It is further clear that the submissions made in Paragraph 3 of this report entitled "Epoxy resin" presuppose (cf. points 3.2 and 3.4) that it was known that an epoxy resin was present in the composition and that it might be of non aromatic nature.

3.29.3 In contrast to the expert of the Appellant, the skilled person trying to analyse the product PSX-700 before the claimed priority date of the patent in suit was not even aware of the presence of an epoxy resin in that product, so that the submissions of the expert concerning the detectability of a non aromatic epoxy resin in that product cannot be relevant for demonstrating such detectability before the claimed priority date of the patent in suit, since they are clearly based on hindsight.

3.29.4 Nevertheless, the Board notes, on the one hand, that, according to the expert of the Appellant (cf. point 3.4 of Evidence 11) the non occurrence of absorption bands in the IR spectrum in the region around 830 cm**(-1)would exclude the presence of an aromatic epoxy resin, and on the other hand, that the IR spectrum of the PSX-700 resin component precisely shows a broad absorption band in the region between 775 and 890 cm**(-1)(Evidence 20). Thus, a skilled person having followed the indications given by the expert of the Appellant would hence at best have concluded that an aromatic epoxy resin instead of a non aromatic epoxy one might have been present in the resin component of the PSX-700.

3.30 Consequently, the Board can only come to the conclusion that it has not been shown by the Appellant that the non aromatic epoxy resin having the chemical structure of the EPONEX 1513 could have been detected by a skilled person in the PSX-700 resin component with analytical means available before the claimed priority date. In other words, at least for this reason, the composition of the product PSX-700 was not available to the public before the claimed priority date.

3.31 Thus, in accordance with the principles set out in decision G 1/92, the composition of the PSX-700 product sold before this priority date is not part of the state of the art for the purpose of Article 54(2) EPC.

3.32 Since lack of novelty of the claimed subject-matter has been alleged by the Appellant only in view of the prior sale of the PSX-700 product, the subject-matter of Claims 1 to 25 must be regarded as novel.

4. Closest state of the art, the technical problem

4.1 The patent in suit relates to epoxy resin/polysiloxane coating compositions.

4.2 Such compositions are known from document D3, which the Board in accordance with the Opposition Division regards as the closest state of the art.

4.3 D3 relates to a method for preparing an interpenetrating polymer network having an epoxy network intertwined with a polysiloxane network comprising the steps of:

a) mixing a silane with an epoxy resin having at least two oxirane groups per molecule, the silane being selected from the group consisting of alkoxysilane, alkyltrialkoxysilane, aryltrialkoxysilane, and hydrolytic polycondensation products thereof;

b) distributing water substantially uniformly throughout the mixture in an amount sufficient to bring about substantial hydrolytic polycondensation of the silane to form a polysiloxane network;

and c) substantially simultaneously reacting the epoxy resin with an amino curing agent to form a polymerized epoxy resin network intertwined with the polysiloxane network (Claim 1).

4.4 The coating compositions prepared containing this IPN can be applied to a surface to be treated by conventional techniques such as spraying or brushing. The components of the coatings are supplied in a two-package system. One package contains the amine curing agent, which can include aminosilane and any accelerating agent if desired. Some solvent can be included with the curing agent. The other package contains the epoxy resin which may optionally include epoxysilane, solvent and fillers (page 15, lines 30 to 32; page 16, lines 9 to 15).

4.5 According to D3, the epoxy resins which could used are those disclosed in the US patent No. 3 183 198 from column 3, line 27 to column 4, line 64 (page 8, lines 26 to 32). While the mentioned passage of this US patent generally mentions aliphatic and cycloaliphatic epoxy resins and specifically discloses at lines 41, 44, 45, and 50 of column 3, four non-aromatic epoxy resins, preference is clearly given in that document to aromatic epoxy resins (column 3, lines 65 to 68), and in all the examples D3 only aromatic epoxy resins are used.

4.6 As stated in D3, these interpenetrating polymer networks have substantial advantages over conventional epoxy polymers. D3 coatings containing these interpenetrating polymer networks IPN because of high cross-link density obtained in the presence of the polysiloxane, exhibit superior thermal stability, greater chemical and solvent resistance, and higher acid resistance than coatings containing the corresponding epoxy polymer. Coatings containing the interpenetrating polymer network are resistant to attack by strong solvents, such as acetone, methanol, and low-molecular weight amines, and provide corrosion, chemical, solvent, weathering, and heat resistance. Examples of surfaces on which these compositions can be used are steel structures of chemical processing plants, oil refineries, coal-fired power plants, and offshore drilling platforms (page 19, line 30 to page 20, line 15).

4.7 While according to the patent in suit its aim is to provide composition having improved weathering, corrosion and chemical resistance (Paragraph [0010]), in the absence of comparative data between the compositions of D3 and those of the patent in suit, the technical problem starting from D3 must be seen in the provision of further coating compositions having good weathering, corrosion, and chemical resistance.

4.8 According to the patent in suit, this problem is solved by providing a composition comprising a polysiloxane, a non aromatic epoxy resin, a difunctional amine hardener, and an organooxysilane which lead to the formation of a fully cured non interpenetrating polymer network.

4.9 In view of the Examples 1 to 3 of the patent in suit, the Board is satisfied that the problem is effectively solved by the claimed measures.

5. Inventive step

5.1 It remains to be decided whether the solution of the technical problem would have been obvious in view of the prior relied on by the Appellant, i.e. documents D2 and D3.

5.2 As indicated above in paragraph 4.6, D3 clearly associates the good chemical, corrosion, and weathering properties to the specific structure of the interpenetrated polymer network obtained. While the possibility of using non aromatic epoxy resins is mentioned in D3 (cf. paragraph 4.5 above), this is done in the Board's view, in passing and it is evident that this possibility cannot be not associated with any suggestion that this use might lead, in total contrast to the general teaching of D3, to the obtaining of a non-interpenetrating polymer network. Thus, D3 itself cannot render obvious the solution proposed in the patent in suit.

5.3 Nor could document D2 provide a hint to the solution proposed in the patent in suit, since while referring to polysiloxane coatings, it is totally silent on the use of epoxy resins therein, let alone the use of non aromatic epoxy resins.

5.4 Consequently, the subject-matter of Claims 1 to 25 must be considered as involving an inventive step (Article 56 EPC).