T 0082/08 22-03-2011

Reasons for the Decision

Main request

1. Inventive step

1.1 The closest prior art document is D2. This was the view of the appellant and the respondent. The Board agrees with this view.

1.2 Also the parties, and the Board, agreed that at least the features of the preamble of claim 1 are disclosed in D2.

1.3 There was disagreement between the parties as to whether the feature of claim 1 according to which the curing takes place in less than three seconds is disclosed in D2. It is not necessary for the purposes of the present decision to decide on this point since the Board has come to the conclusion, as will be explained below, that the provision of this feature as well as the feature relating to the minimum energy density was obvious to the skilled person.

1.4 The problem to be solved by the features of the characterising portion of the claim is according to the appellant to reduce the curing time, and according to the respondent to reduce the curing time whilst maintaining conductivity and hence weldability.

The Board agrees with the respondent, noting that weldability is a requirement for instance in the car industry which is mentioned in D2, and the skilled person would have to fulfil this requirement.

1.5 With regard to the feature that the curing takes place in less than three seconds the appellant argued that the skilled person would be attempting to shorten this time because it could determine the speed of the production line and so he would always want to reduce this so that the curing of the paint does not become a limitation on the production line. The respondent had argued that the curing times in the process known from D2 were greater than three seconds but acknowledged that there would be a desire to reduce this time.

In the view of the Board the skilled person would want to reduce the curing time for the reasons explained by the appellant and the time of three seconds in fact is a result of the other feature, i.e. the minimum energy density, rather than an independent feature. This point was also made by the appellant. As indicated by the appellant this feature in fact describes a desire that the skilled person would want to fulfil.

1.6 The crucial question therefore is whether the skilled person would increase the energy density for the existing near infrared radiation compared to existing levels in order to solve the problem. The respondent also considered in its letter of 22 July 2010 (see page 2, last paragraph) that this was the main distinguishing feature of the claim.

According to the respondent the energy density in the process of D2 would have been approximately 170 kW/m2 (see letter of 26 January 2004, page 2, filed during grant proceedings and refiled in the opposition proceedings with letter of 20 September 2007).

The appellant did not dispute this finding regarding the energy density in D2 but argued that in 1985 when D2 was published this would have been the maximum value for the lamps then available. In the fifteen years to the filing date of the patent in suit (no priority was claimed) the power of the lamps available on the market had increased considerably so that at the filing date it was possible to use more powerful lamps made by IndustrieSerVis GmbH. The appellant pointed out that it is indicated in D3 (see page 1387, right hand column, first paragraph) that these lamps could deliver up to 15 MkW/m2, i.e. 15.000 kW/m2, which is well above the minimum specified in claim 1. This was not disputed by the respondent.

D3 is a report of a symposium organised by that company on the applications for such lamps. Their suitability for use in the drying process of paint is set out in the paragraph bridging pages 1378 and 1379. It is also explained that they are particularly useful in this respect since they can make the paint dry from the inside out due to the radiation which reaches the substrate being reflected therefrom back into the paint from the bottom.

The Board agrees with the appellant that, animated by D3, the skilled person would want to apply the more powerful lamps available at the filing date to the process known from D2 in order to reduce the curing time.

The principal argument of the respondent is that there was a prejudice for the skilled person against raising the energy density since he would be afraid that this could negatively affect the weldability of the painted sheets.

The Board cannot agree with this argument. In a situation where the skilled person can expect to solve a problem, here reducing curing time by using a more powerful lamp, a prejudice can only then arise when the skilled person is certain that the measure will not work. A mere argument that he would be afraid that it would not work cannot be considered sufficient to prevent him from trying the measure since the benefits of success are considerable.

Also the argument of the respondent relies on tests that it carried out measuring the conductivity. The first test was performed with induction heating and hence would not produce a prejudice against near infrared radiation heating, which by its nature is different in its heating effect on the paint, cf. D3, figure 2. The second test also applies the heating to sample B differently to the manner described in D2, i.e. it is applied to the backside. These tests do not therefore show a prejudice against applying a higher energy density of near infrared radiation in the same manner as in D2, i.e. by radiation onto the paint. Moreover, a prejudice should be proven to be the common thinking, e.g. by citing handbooks, rather than arising from the results of a particular type of testing not even publically available at the filing date.

1.7 Therefore, the subject-matter of claim 1 of the main request does not involve an inventive step in the sense of Article 56 EPC.

First auxiliary request

2. Inventive step

2.1 Claim 1 of this request includes the extra feature that the sheets that are produced are bake hardenable.

2.2 The appellant accepted that neither D2 nor D3 explicitly mention sheets that are bake hardenable. It pointed out, however, that D2 refers to using the curing method in the production of metal sheets for the car industry and that it is a requirement of the car industry for pre-painted sheets that they should be bake hardenable.

2.3 The respondent accepted that it was a requirement in the car industry that the sheets are bake hardenable, but it considered that this requirement added to the problem since it was desired that the curing time be reduced whilst retaining this function.

2.4 The Board does not find the argument of the respondent to be convincing. According to paragraph [0040] of the patent in suit (paragraph [0043] of the application as published) the property of being bake hardenable is lost if the curing time is too long. The Board has already indicated with respect to the main request that there existed a desire to reduce the curing time. Since this reduction would also ensure that the sheets remain bake hardenable the extra feature is one which is automatically already achieved with the features of claim 1 of the main request, which has already been found to lack an inventive step (see point 1 above).

2.5 Therefore, the subject-matter of claim 1 of the first auxiliary request does not involve an inventive step in the sense of Article 56 EPC.

Second auxiliary request

3. Inventive step

3.1 According to claim 1 of this request there is a pre-treatment step before the painting step.

3.2 As pointed out by the appellant and acknowledged by the respondent a pre-treatment is known from D2 (see page 7, lines 8 to 14 and page 8, lines 1 to 8 where the particular treatments are discussed).

The appellant considered that D2 therefore removed any prejudice against applying near infrared radiation where a sheet has been pre-treated.

3.3 The counterargument of the respondent was that the feature increased the prejudice for the skilled person since even if he considered that increasing the energy density for the near infrared radiation might work on a painted sheet he would not expect to be able to maintain weldability where the sheet has been pre-treated.

The respondent further considered that the adhesion to the pre-treatment layer was improved by the higher energy density.

3.4 The Board cannot agree with the arguments of the respondent regarding a prejudice for the reasons already explained above with respect to the main request. The Board also does not consider that it has been shown that this prejudice would have been so changed by the presence of a pre-treatment that the skilled person would have considered that it was impossible to maintain the weldability when applying near infrared radiation of increased energy density to a painted pre-treated sheet. D2 already includes a pre-treatment so that the argument of the respondent that the skilled person would expect a problem at the interface between the pre-treatment layer and the paint layer when using near infrared radiation is not well founded.

With respect to the allegedly improved adhesion of the paint to the pre-treatment layer the Board notes that this was not proven. Moreover, this would only be an advantage resulting from a method that was already obvious for other reasons.

3.5 Therefore, the subject-matter of claim 1 of the second auxiliary request does not involve an inventive step in the sense of Article 56 EPC.

Fourth auxiliary request

4. Inventive step

4.1 According to claim 1 of this request the pre-treatment layer is heavy metal free. As pointed out by the appellant, in D2 (see page 8, lines 1 to 8) the pre-treatments proposed therein are phosphate and chromate treatments, whereby a phosphate treatment is free of heavy metals.

In the time between the publication date of D2 and the priority date of the patent in suit there was a move towards making production methods more environmentally acceptable, which included avoiding heavy metals. The skilled person would thus at the filing date prefer the phosphate treatment over the chromate treatment.

4.2 The respondent argued that heavy metal free treatments are more susceptible to deterioration of conductivity and hence weldability so that the skilled person would be even less inclined to increase the energy density with this type of pre-treatment.

4.3 The Board cannot agree with this argument of the respondent. Quite apart from the fact that it represents an unproven allegation the fact that the car industry was requiring heavy metal free pre-treatments means that the skilled person would not be influenced by fears that there could be problems with such pre-treatments at high energy density since he knew that this was required and hence would do this.

4.4 Therefore, the subject-matter of claim 1 of the fourth auxiliary request does not involve an inventive step in the sense of Article 56 EPC.