T 1336/17 13-01-2020

1. Request for remittal

1.1 The respondent requested that the case be remitted to the opposition division for the assessment of novelty and inventive step, because no decision had been taken by the opposition division on these issues, at least as far as the main and the first to third auxiliary requests were concerned. Since only the issue of inventive step is assessed in the present decision, the respondent's request is only addressed as far as it relates to this issue.

1.2 The board considers that a remittal is not the appropriate course of action in the present case. Since the issues relevant to the present case, as shown below, have already been dealt with by the opposition division during the opposition proceedings, there is no reason to remit the case (Article 111(1) EPC).

It is not disputed that inventive step was not dealt with in the parts of the written decision of the opposition division relating to the main request and to the first to third auxiliary requests (which are identical to the corresponding requests currently on file). These requests were, in fact, found to lack sufficiency of disclosure because not all claimed compositions achieved the technical effect sought (points 4.0 to 7.0 of the written decision). However, inventive step was discussed extensively in the section of the decision under appeal relating to the fifth auxiliary request (the fourth auxiliary request currently on file). The subject-matter of this request, which was found to meet the requirements of sufficiency, was considered novel and also to involve an inventive step over a combination of D1 and D14 (point 9.7). Furthermore, according to the minutes of the oral proceedings before the opposition division inventive step of the subject-matter claimed in the main and first to third auxiliary requests was also discussed during the oral proceedings and that respective conclusions were announced orally (see points 3.3 and 4). The written decision and the minutes also show that for assessing the sufficiency and inventive step of all requests the relevant issue was whether component d) induced a technical effect. This issue, which is relevant in the present appeal proceedings, was therefore also dealt with during the proceedings before the opposition division.

2. Request not to admit into the appeal proceedings certain submissions

2.1 The appellant requested that the respondent's submissions presented in the letter dated 19 December 2019, and the inventive step objection based on the combination of D1 with D14, not be admitted into the appeal proceedings. Since the present decision only concerns the assessment of inventive step in view of the combination of D1 with D14, the appellant's request is only addressed in so far as it relates to this issue.

2.2 As already indicated above (point 1.2), the inventive step attack based on a combination of D1 and D14 was raised during the proceedings before the opposition division in relation to all requests currently on file. The written decision on this point was issued in respect of the fifth auxiliary request, whereas conclusions on the other requests were only announced orally during the oral proceedings (see minutes).

2.3 In its reply to the statement setting out the grounds of appeal, the respondent stated that it was maintaining the inventive step objection. The appellant argued that this objection was not substantiated and that for this reason all later submissions had to be disregarded.

2.4 As already mentioned above, the opposition division considered that the issue of whether component d) of the claimed adhesive composition induced a technical effect and contributed to the solution of the underlying technical problem was crucial in the context of both sufficiency and inventive step. When examining the main and the first to third auxiliary requests, the opposition division concluded that this effect was not achieved over the entire scope claimed. In view of this conclusion, it decided that the invention claimed in these requests was insufficiently disclosed.

2.5 During the appeal proceedings the board considered that the aforementioned issue was highly relevant and had to be discussed and decided upon in the context of inventive step. In its communication issued in preparation for the oral proceedings, the board had expressed the opinion that the opposition division's finding that sufficiency of disclosure was not complied with because a non-claimed effect was not achieved was not correct, and inventive step was mentioned as a point to be discussed. The board considered that during the oral proceedings both parties should be given the opportunity to present their case on the relevance of component d) in the context of the inventive step attack, and to take into account, at the least, the objection and the documents (D1 and D14) dealt with in the decision under appeal and during the oral proceedings before the opposition division.

2.6 For these reasons, the board admitted into the appeal proceedings the objection of inventive step based on the combination of D1 with D14 (Article 13(1) RPBA 2020).

Main request

3. Inventive step

3.1 The claimed invention relates to an epoxy adhesive composition useful for bonding parts of a vehicle. In the manufacturing process of a vehicle, the body-in-white structure to which the structural adhesive has been applied is usually subjected to spray wash followed by phosphatising and e-coating prior to the final curing of the structural adhesive in the e-coat oven. The invention aims to provide an adhesive which is not washed off during the spray wash step. The idea underlying the invention is to provide a composition having a relatively low viscosity at application temperature but which exhibits a high viscosity at low shear strain after application and cooling down, so as to offer high wash-off resistance without the need for a pre-hardening step (paragraphs [0009] and [0012] of the patent in suit).

3.2 The opposition division decided, and the parties agreed, that D1 represented the closest prior art and that the claimed composition differed from that disclosed in D1 in that it comprised the polymeric component d) defined in claim 1. The board has no reason to deviate from this finding. D1 discloses an epoxy adhesive composition suitable for bonding parts of a vehicle which is wash-off resistant before the final hardening step (page 6, 2**(nd)paragraph; page 7, 1**(st)and 2**(nd)paragraphs; and claims).

3.3 According to the appellant the idea in D1 was to achieve wash-off resistance by either: a) providing a composition having a low viscosity at application temperature which had to be pre-gelled after application to induce an increase in viscosity, or b) providing a composition having a high basic viscosity. The first approach suffered from the drawback that a pre-gelling step was required during the production process, whereas the second had the disadvantage that the adhesive was difficult to apply.

3.4 The claimed invention was based on the finding that the addition of the polymeric component d) to a composition as described in D1 resulted in an adhesive composition having very low viscosity at application temperature which, when cooled down to room temperature, had high viscosity at low shear temperature and was thixotropic. This high viscosity gave the composition wash-off resistance without the need for a pre-gelling step. This effect was induced by component d). This component softened at high temperatures and re-thickened by partial crystallisation when cooled down to room temperature (paragraph [0012] of the patent in suit).

3.5 As evidence of these properties the appellant referred to Tables 1 and 3 of the patent in suit, and in particular to the composition of sample BM 1460.005. The viscosity of this composition was very low at 45°C (63 Pas: see Table 1) and its yield stress was 420 Pa, indicating that it was very simple to apply. However, after exposing the composition to a temperature of 60°C for 15 minutes and letting it cool down to room temperature, a viscosity of 19500 Pas was observed (at a shear strain of 0.001 and a frequency of 10 Hz: see Table 3). This viscosity was nearly 4 times as high as that (5000 Pas) observed using a comparative composition which differed from the first one in that it did not contain the component d).

3.6 Relying on these tests, in its statement setting out the grounds of appeal the appellant formulated the objective technical problem as that of "providing an epoxy adhesive composition which results in a cured product having high static and dynamic strength and a good corrosion resistance, said adhesive composition being wash-off resistant prior to curing, without the need for pre-curing, and at the same time being very simple to handle".

3.7 What is in dispute is whether the available evidence allows the conclusion that this problem is solved over the entire scope of the claimed subject-matter.

As noted by the respondent and by the opposition division in its decision, the composition of Example BM 1450.002, which comprises a polymer (Tone 1278) falling within the definition of ingredient d) given in claim 1, does not achieve high viscosity after being heated and then cooled down to room temperature. Its viscosity is 4000 Pas, and thus considerably lower than that of the composition of the comparative example BM 1480 (5000 Pas: Table 3) which, as clarified by the appellant during the oral proceedings before the board, does not comprise a component d).

3.8 The appellant noted that in Example BM 1450.002 the viscosity had increased from 1300 Pas to 4000 Pas after 1 day. A further increase in viscosity could not be ruled out if the composition was left to stand for a longer period.

This argument is not convincing. In the first place, no credible evidence or argument was provided to support this allegation. Furthermore, it appears credible that, as stated by the respondent, the viscosity will not increase linearly, but rather level off one day after cooling down. Secondly, if the appellant's arguments were accepted, the question of when the viscosity of the other compositions was measured would have to be clarified.

3.9 The appellant has also argued that a viscosity of more than 4000 Pas was not necessary to achieve wash-off resistance: the ratio between the viscosity at the higher application temperature and at room temperature was also important. This ratio was higher for the composition of sample BM 1460.002 than for the comparative example BM 1480.

These arguments are not persuasive either, because they contradict the teaching of paragraph [0012], which attaches a particular significance to a viscosity of more than 19000 Pas for achieving wash-off resistance. Moreover, the viscosity of the composition of sample BM 1480 at 45°C (comparative; 53 Pas) lies among those of the compositions according to the invention, which are considered easy to apply, and its viscosity after cooling is higher (5000 Pas) than that of the composition of sample BM 1460.002 (4000 Pas).

3.10 For these reasons, it is concluded that the composition of sample BM 1460.002 does not fulfil the requirement of being both easy to apply and wash-off resistent. This means that for this composition the distinguishing technical feature, component d), does not contribute to the solution of the technical problem formulated above in point 3.5, and that that problem is not solved over the entire scope claimed.

3.11 The appellant has also proposed formulating the problem as the provision of an adhesive composition having a ratio of at least 200 between the viscosity at 45°C and that at room temperature. However, this problem cannot be derived from, and even contradicts, the teaching of the aforementioned paragraph [0012].

The appellant further asserted that after cooling the compositions of the invention manifested higher thixotropy than those of the prior art. However, during the oral proceedings before the board it conceded that no such effect was shown in the patent, because the viscosity after cooling was only measured at a low shear rate. Apart from a passing reference in paragraph [0012], the patent does not provide any details or evidence of this effect for any claimed composition, let alone for the composition of sample BM 1460.002. This alleged effect cannot thus be considered either when formulating the underlying technical problem.

3.12 For these reasons it is concluded that, starting from D1, the objective technical problem underlying the claimed invention has to be seen as the provision of an alternative epoxy adhesive composition.

3.13 Faced with this problem, the skilled person would have considered including in the composition of D1 other ingredients typically used in the manufacture of adhesive systems, including Dynacoll® 7330, one of the preferred polyesters used as component d) in the compositions described in the patent in suit. As shown in the technical data sheet D14, Dynacoll® 7330 was already known in the prior art as an ingredient for the manufacture of hot melt adhesives with low melt viscosity and fast setting properties. There is no evidence that the skilled person would have been dissuaded from adding this ingredient to the adhesive composition disclosed in D1. It is also noted that claim 12 of D1 provides the addition of an additional polymer, a polyesterpolyol, to the ternary adhesive composition described in that document.

3.14 For these reasons, it is concluded that the subject-matter of claim 1 of the main request does not involve an inventive step (Article 56 EPC).

First and second auxiliary requests

4. Inventive step

4.1 The subject-matter of claim 1 of the first auxiliary request differs from that of the granted patent in that component d) is a polyester and that of the second auxiliary request in that component d) has a molecular weight in the range from 2000 to 5000 g/mol.

4.2 Since the definition of component d) which is given in both these requests still encompasses Dynacoll® 7330, disclosed in D14, the conclusions drawn in respect of claim 1 of the main request also apply to claim 1 of the first and second auxiliary requests. Thus, the subject-matter of claim 1 of these requests does not involve an inventive step either (Article 56 EPC).

Third auxiliary request

5. Inventive step

5.1 Claim 1 of the third auxiliary request differs from that of the granted patent in that the amount of component d) in the composition is from 5 to 15 wt%.

5.2 The appellant argued that, since the opposition division had orally expressed the opinion that the subject-matter of this request involved an inventive step (minutes of the oral proceedings, point 5.2), there was even more reason not to admit the inventive step objection over the combination of D1 with D14.

This argument is not convincing. The reasons for admitting the inventive step attack based on a combination of D1 with D14 in the appeal proceedings have already been discussed above (points 2.4-2.6). These reasons apply equally to the third auxiliary request, irrespective of any conclusion announced during the oral proceedings. This is all the more true because a final decision was not taken on this issue and the reasons for the finding were not given.

5.3 The appellant has provided no evidence or argument that the presence of an amount of 5 to 15 wt% of component d) in the adhesive is associated with a new technical effect. For this reason, the selection of this amount is considered to be arbitrary. Nor is any evidence available that the skilled person would have been dissuaded from adding this ingredient in this amount. The appellant noted that Example 1 and Table 1 of D1 described a composition comprising an ester in an amount outside the claimed range. However, this ester was used for the preparation of "component B" of the ternary composition comprising "components A), B) and C)" described in D1. Thus, the amount shown in Example 1 and Table 1 is not that of an ingredient which is added to that composition and corresponds to the component d) of claim 1.

5.4 For these reasons, the conclusions drawn in respect of claim 1 of the main request also apply to claim 1 of the third auxiliary request. Thus, the subject-matter of this claim does not involve an inventive step (Article 56 EPC).

Fourth auxiliary request

6. Prohibition of reformatio in peius

6.1 Since in the present case the patent proprietor is the sole appellant against the interlocutory decision of the opposition division, the principle of prohibition of "reformatio in peius" applies (G 9/92 and G 4/93). Consequently, the set of claims according to the fourth auxiliary request, which is identical to the set of claims regarded by the opposition division as a basis on which the patent could be maintained, cannot be challenged in appeal proceedings.

7. Other issues

7.1 In view of the aforementioned conclusions there is no need to elaborate on the issues of novelty and sufficiency of disclosure.