T 1476/21 04-06-2024

Reasons for the Decision

1. Oral proceedings held in the absence of opponent 2

Opponent 2 was duly summoned but indicated that they would not attend or be represented at the oral proceedings before the board.

Oral proceedings therefore took place in the absence of opponent 2 according to Rule 115(2) EPC and Article 15(3) RPBA.

The principle of the right to be heard according to Article 113(1) EPC has been observed as Article 113(1) EPC only affords the opportunity to be heard. By absenting itself from the oral proceedings, a party gives up that opportunity (see Case Law of the Boards of Appeal, 10th edition 2022 ("CLB" hereinafter), III.B.2.7.3 b)).

2. Main request - Article 83 EPC

2.1 The opposition division found that the claimed invention was sufficiently clearly and completely disclosed for it to be carried out by a person skilled in the art (see decision under appeal, point 16.1.2).

2.2 This finding was contested by the appellant who argued that the following features were not sufficiently disclosed:

(a) in claim 1, feature F1.2 "cold formable cold rolled steel"

(b) in claim 1, feature F1.4.1 "the siloxane or polysiloxane layer having a layer thickness corresponding with 1 - 8 mg/m**(2) Si"

(c) in claim 5, the feature of "the siloxane or polysiloxane layer having a layer thickness corresponding with 1 - 5 mg/m**(2) Si".

2.3 The board notes that it is established case law that a successful objection of insufficient disclosure presupposes that there are serious doubts, substantiated by verifiable facts (CLB, II.C.9.).

The appellant has not provided any evidence that it was unable to produce a strip or sheet having the features of claims 1 and 5 and relies on arguments alone in support of its objections.

2.4 Claim 1 - feature F1.2

2.4.1 The appellant argued that feature F1.2 was not sufficiently disclosed because the skilled person was not taught which steel could be used to implement the invention.

According to the appellant, in the final sentence of paragraph [0012] of the contested patent, it was stated that the claimed invention was not directed to a steel for hot forming at a temperature of 600 C or above. However, the steel composition given in paragraph [0013] of the contested patent as well as "steel grade 1", indicated as a boron steel (paragraph [0029] of the contested patent), were both intended to be shaped above 600 C, so that these steels were apparently not in accordance with the invention and the contested patent did not disclose which steel compositions could be used for the invention.

2.4.2 The board however agrees with the reasoning of the opposition division that the appellant did not provide any evidence that the steel compositions covered by the disclosure of paragraph [0013] were not suitable to be cold formed.

Even when the description is taken into account, the skilled person understands that the cold formable steel may also be hot formable, in particular as a steel suitable for cold forming is also expected to be suitable for hot forming (see decision under appeal, point 16.1.2).

Further, boron steels (such as described in paragraph [0029]) may be hot or cold formed.

2.4.3 The appellant has therefore not convincingly demonstrated that the opposition division was incorrect in finding that feature F1.2 was sufficiently disclosed.

2.5 Claim 1 - feature F1.4.1

2.5.1 The appellant argued that feature F1.4.1 was not sufficiently disclosed as no method for determining the thickness of the layer was mentioned in the contested patent. It was not set out in the contested patent how to determine whether the siloxane or polysiloxane layer had a layer thickness corresponding with 1-8 mg/m**(2) Si, and if this related to a wet or dry layer.

In addition, it was not specified how the layer should be produced, for example, the concentration or quantity of bis-triethoxysilylethane (BTSE) and aminopropyltriethoxysilane (APS) to be deposited, or the type and duration of drying.

2.5.2 The board concludes that feature F1.4.1 is sufficiently disclosed.

Paragraphs [0017] and [0031] give details of the chemicals which can be used to form the siloxane layer and how they can be applied.

The skilled person using their common general knowledge is aware of how to dry water-based solutions. As no specific drying steps are given, the skilled person understands that any suitable form and duration of drying can be used.

Paragraph [0017] of the contested patent sets out a number of possible chemicals for the siloxane or polysiloxane layer. As the respondent argued, the skilled person, knowing the chemical compositions used and the size of the sheet, is able to calculate the amounts of chemicals required to give a layer corresponding to 1-8 mg/m**(2) of Si, regardless of whether the layer is wet or dry.

2.5.3 The appellant's objection to the lack of a specific method for measuring the silicon content of a wet or dry (poly)siloxane layer appears to be an objection of lack of clarity of the claim, rather than insufficiency of disclosure as it relates to the ability to determine whether a sheet or strip, which has already been made, falls within the scope of the claim or not.

As feature F1.4.1 was present in claim 5 as granted, it cannot be examined for compliance with the requirements of Article 84 EPC (see G 3/14).

2.5.4 The board agrees with the respondent that the skilled person is able to determine the content of silicon in a (poly)siloxane layer using their common general knowledge of analytical practices.

The appellant has not provided any evidence supporting its allegations that commonly-used methods would not be suitable and has therefore not discharged its burden of proof that despite making all reasonable efforts it was unable to put the invention into practice (CLB, III.G.5.1.2 c)).

2.6 Claim 5

The feature objected to in claim 5 of the main request corresponds to feature F1.4.1 but with a narrower claimed range. This feature was also present in claim 5 as granted.

Claim 5 therefore fulfils the requirements of Article 83 EPC for the same reasons as given above for feature F1.4.1 of claim 1.

2.7 The board concludes that the claimed invention is sufficiently disclosed and the requirements of Article 83 EPC are fulfilled.

2.8 In light of this conclusion, it is unnecessary to consider the respondent's request to admit documents D19 and D20 into the appeal proceedings as these documents were filed in support of the respondent's arguments relating to sufficiency of disclosure.

Main request - claim 1 - Article 56 EPC - inventive step

3. In view of document D18 with D4 or D10 together with D8, D14, D15 or D16

3.1 Admittance of D18

3.1.1 The opposition division did not admit document D18 into the opposition proceedings. It reasoned firstly, that a document cannot be prima facie relevant if it is to be used for inventive step, and secondly, that even if document D18 was considered substantively, as it disclosed values of aluminium and magnesium in the zinc alloy which were outside the range claimed in claim 1, it was not prima facie relevant as it was not apparent why the skilled person would change the ratio in view of the many possibilities to modify the coated sheet steel of D18 (see decision under appeal, point 15.2.2).

3.1.2 The appellant requested that document D18 be admitted into the appeal proceedings.

The appellant argued that the opposition division was incorrect in reasoning that a document used for an inventive step objection cannot be prima facie relevant. According to the appellant a newly filed document does not have to be more relevant than any other document, it is sufficient if it could influence the outcome of the decision. In addition, the appellant argued that the opposition division failed to take into account that document D18 had to be considered in combination with document D4, and not considered alone.

3.1.3 As noted by the respondent, evidence and objections which are not admitted by the opposition division should not be admitted into appeal proceedings unless the decision not to admit them suffered from an error in the use of discretion or unless the circumstances of the appeal case justify their admittance (Article 12(6), first sentence, RPBA).

3.1.4 In the present case, although the opposition division was incorrect in stating that a document used for inventive step cannot be prima facie relevant, as the opposition division did also then consider the appellant's substantive arguments relating to inventive step, the board considers that the opposition division exercised its discretion according to the correct principles, without using the wrong principles and in a reasonable manner.

It is established case law that when reviewing a discretionary decision it is not for the board to review all the facts and circumstances as if it were the opposition division and decide whether or not it would have exercised its discretion in the same way (CLB, V.A.3.4.1 b)).

The opposition division used the criterion of prima facie relevance which is understood as being a decisive criterion for the admittance of late-filed documents (see CLB, IV.C.4.5.3, first paragraph).

After considering the parties' submissions (see minutes of the oral proceedings before the opposition division, points 30-35) the opposition division found that there was prima facie no reason to change the ZnAlMg alloy layer composition of document D18 (see decision under appeal, point 15.2.2, second paragraph).

Therefore, even if the opposition division did not explicitly mention D4, it clearly referred to the appellant's objection and arguments as it considered that it was not apparent why the composition of the alloy in D18 should be changed.

3.1.5 The board thus sees no reason to overturn the opposition division's decision. Document D18 (as well as the objections based upon it) is therefore not admitted into the appeal proceedings.

3.2 As documents D21 to D24 were filed in support of the parties' interpretations of the technical content of document D18, it is unnecessary to consider their admittance into the appeal proceedings.

4. In view of document D3 with D4 or D10 and D8, D14, D15 or D16

4.1 In its statement of grounds of appeal the appellant argued that D3 showed all features of claim 1 of the main request, apart from F1.3.2 to F1.3.4 and F1.5

4.2 The respondent argued that features F1.1 and F1.4.1 were also not disclosed in document D3.

4.2.1 According to the respondent, D3 did not disclose a strip or sheet but related to a method for providing a repair coating on a painted car body or part of it (D3, paragraph [0001]).

The thicknesses of siloxane compositions referred to in paragraph [0002] of D3 did not specify the Si content, so that a range of 1 - 8 mg/m**(2) Si could not be regarded as disclosed in D3.

4.3 The opposition division found that feature F1.1 was present in D3, paragraph [0025], as claim 1 of the main request "is directed to a coated steel product as such" (decision under appeal, page 12, second paragraph).

The appellant argued that paragraphs [0001], [0002], [0028], [0029] and [0163] of D3 showed the use of metal sheets.

4.3.1 In the board's view, paragraph [0025] of D3 does not disclose a sheet or strip as it mentions only "at least one metallic surface". Paragraphs [0001], [0002], [0028], [0029] and [0163] do not show the combination of feature F1.1 with the further features of claim 1 said to be disclosed in D3.

Paragraph [0001] does not explicitly mention sheets or strips, paragraph [0002] does mention "hot, warm or cold formed metallic sheets", in relation to the prior art, which have "flaws that may be seen after finishing", and the removal of coatings when removing such flaws, no mention of a zinc alloy layer or siloxane layer is made.

Paragraphs [0028] and [0029] do refer to applying siloxane composition to the metallic surface of sheets, but do not give any detail of the siloxane layer applied.

In the example disclosed in paragraph [0163], hot-dipped galvanised steel sheets are described with an e-coat on a zinc phosphate coating. However, these coatings are said to have then been sanded in a removal area Z, such that in the middle of the sheet, blank metal can be seen, and a thin layer of this metal may also be removed.

The appellant argued that the "blank metal sheet" present after removal of the coatings was the zinc alloy layer.

However, as argued by the respondent, paragraph [0030] of D3 indicates that often "even the very thin zinc-rich metallic coatings are totally removed in the middle of the removal area Z."

Therefore, when the siloxane composition is applied over removal area Z, to generate a coating B as described in paragraph [0164], it is not unambiguously disclosed that feature F1.3 is still present.

In any case, there is no disclosure of feature F1.4.1 together with F1.1 in this example.

Paragraph [0164] describes the coating B as having a dry film thickness of about 25 to 80 mym. The appellant has not indicated how this layer fulfils the requirements of feature F1.4.1.

The appellant refers to a thickness range disclosed in paragraph [0020] of document D3 as disclosing F1.4.1. None of the ranges in paragraph [0020] have any overlap with the range mentioned in paragraph [0164].

4.4 Furthermore, the board is of the view that paragraph [0020] does not directly and unambiguously disclose feature F1.4.1.

4.4.1 The appellant argued that as the respondent had stated during examination proceedings that a range of 1 to 10 mg/m**(2) Si corresponded to a thickness of 20 to 120 nm of a layer of siloxane, that paragraph [0020], which discloses a thickness range of 10 to 200 nm must implicitly disclose a range of 1 to 8 mg Si/m**(2)as set out in feature F1.4.1.

4.4.2 The board cannot follow this argument. There is no disclosure in D3 of an amount of Si per unit area for the siloxane coatings. The appellant has not shown that the skilled person, using their common general knowledge, understands from D3 that a thickness range of the layer from 10 to 200 nm inherently correlates to any specific range of amounts of Si per unit area.

Indeed in its submissions of 13 May 2024 the appellant appears to be of the view that a range of 1 to 10 mg/m**(2) Si should correlate to a layer thickness range of between 20 and 200 nm, rather than the 120 nm referred to by the proprietor, in order to keep the proportionality ratios.

The board does not share the appellant's view which is a mere allegation with no basis. There is no reason to believe that a linear relationship exists between the two dimensions: mg/m**(2) and nm. Hence, the disclosed range of 10 to 200 nm is unambiguously broader than the claimed range of 1 to 8 mg/m**(2) converted into nm.

The skilled person therefore cannot directly and unambiguously derive from a preferred thickness layer of the film B of a siloxane composition of 10 to 200 nm that the layer has a Si content of 1 to 8 mg/m**(2).

4.5 There is no direct and unambiguous disclosure of feature F1.4.1 in document D3 and even if feature F1.1 alone may be considered to be disclosed in D3, there does not appear to be a direct and unambiguous disclosure of feature F1.1 together with the further features.

4.6 As a combination of the teaching of document D3 with D4 or D10 and D8, D14, D15 or D16 does not contain feature F1.4.1, the subject-matter of claim 1 is considered to be inventive with respect to this combination of documents.

5. In view of document D9 with D4 or D10 and D8, D14, D15 or D16

5.1 The opposition division found that document D9 showed all features of claim 1 of the main request apart from features F1.3.1, F1.3.2 and F1.5 (see decision under appeal, page 11, first paragraph).

5.2 The appellant argued that D9 disclosed all features apart from features F1.3.2 to F1.3.4 and F1.5.

The appellant viewed the inorganic coating containing silicon oxide (D9, paragraph [0009]; see D9a the translation into English) as disclosing features F1.4 and F1.4.1.

The opposition division found that paragraphs [0009], [0016] and claim 1 disclosed features F1.4 and F1.4.1.

5.3 The respondent contested that D9 disclosed features F1.4 and F1.4.1 as in D9 it is an inorganic coating film containing a silicon oxide which coats the zinc alloy not a (poly)siloxane layer.

5.4 The appellant did not comment substantively on the respondent's arguments relating to the disclosure of features F1.4 and F1.4.1 in document D9 in its written submissions or at the oral proceedings before the board.

5.5 The board agrees with the respondent that document D9 does not directly and unambiguously disclose features F1.4 and F1.4.1.

5.5.1 Claim 1 of document D9 refers to an inorganic coating film containing silicon oxide with silicon in the range of 5 to 100 mg/m**(2) and containing neither chromium nor an organic substance. Paragraph [0009] also refers to an inorganic coating formed on the surface of the sheet material containing silicon oxide in an amount of silicon of 5 to 100 mg/m**(2). Neither of these passages refers to a (poly)siloxane layer.

Although paragraph [0016] of D9 mentions coating material containing a monomer or polymer having a siloxane bond, an alkoxysilane and/or a silanol group, as the respondent argued, this paragraph refers to a film coating covering the inorganic coating (see D9, paragraph [0015], first sentence and paragraph [0017], second sentence).

5.5.2 Therefore, in the board's view features F1.4 and F1.4.1 are not disclosed as the zinc alloy layer is not coated with a (poly)siloxane layer.

5.6 As document D9 does not disclose features F1.4 and F1.4.1, the appellant's arguments regarding the obviousness of claim 1 in view of the combination of D9 with D4 or D10 and D8 or D14 to D16 are not convincing, as the combination of the teachings would not lead to the subject-matter of claim 1 of the main request.

6. In view of document D13 with D4 or D10 and D8, D14, D15 or D16

6.1 The appellant argued that document D13 disclosed features F1.1, F1.2, F1.3, F1.4 and F1.4.1.

6.2 The opposition division had reasoned that although document D13 disclosed feature F1.3 in paragraph [0083] and features F1.4 and F1.4.1 in examples 4 and 11, document D13 did not disclose a zinc alloy coating on a steel sheet in combination with a (poly)siloxane coating on a zinc alloy coating (see decision under appeal, page 11, final paragraph).

Paragraph [0083] of D13 indicated a large number of possible "iron-based base materials", including zinc-based alloy coated plates.

Examples 4 and 11 showed siloxane coatings as the metal surface treatment, on a bare SPC steel sheet (see D13, Example 1). A number of further metal surface treatment compositions were disclosed in the examples.

6.3 The appellant argued that starting from examples 4 and 11, only one selection was necessary, namely a choice of coating the steel sheet with a zinc alloy layer.

6.3.1 Therefore, starting from example 4 or 11 of document D13, the distinguishing features are regarded as F1.3.1 to F1.3.4 and F1.5.

6.4 The appellant was of the view that no synergetic effect between the distinguishing features F1.3.1 to F1.3.4 and the distinguishing feature F1.5 was present. The two groups of distinguishing features must therefore be considered separately for assessing the inventive step of the subject-matter of claim 1 of the main request.

6.4.1 According to the appellant, the zinc alloy coating specified in features F1.3.2 to F1.3.4 was commonly used in the automotive industry for corrosion resistance, as shown in documents D4 and D10.

Further, it would be obvious for the skilled person to add a layer of oil as this was normal practice in the automotive industry as shown by documents D8, D14, D15 or D16.

6.4.2 The opposition division however had found that there was a synergetic effect arising from the combination of features F1.3.1, F1.3.2, F1.4.1 and F1.5 which together led to "improvement of the rate of cohesive failure in the bond breaking mechanism" (see decision under appeal, 16.3.1 and 16.3.4).

6.4.3 The appellant argued that the contested patent did not demonstrate that the effect from the combination of the features was greater than the sum of the individual effects of the features. According to the appellant, there was no data in the contested patent demonstrating any effect of the presence of a ZnAlMg layer in general or one with the composition of features F1.3.1 and F1.3.2.

6.5 The board however agrees with the opposition division and the respondent that the contested patent shows that the claimed (poly)siloxane coating with an oil covering, leads to better performance in terms of cohesive rather than adhesive failure for a ZnAlMg coated steel sheet (contested patent, paragraph [0035]).

Therefore, there is a technical effect associated with a steel sheet coated with the three layers of a ZnAlMg alloy layer, a (poly)siloxane and oil.

6.5.1 In any case, even if feature F1.5 is considered alone, this has the technical effect of improving cohesive failure, as demonstrated in paragraph [0035] and Table 1 of the contested patent.

The objective technical problem to be solved cannot therefore be seen as merely to provide an alternative as argued by the appellant and instead the objective technical problem is regarded as being that posed in the contested patent, namely of providing a steel strip or sheet with good adhesive bonding (paragraphs [0004] and [0035]).

6.6 The board also agrees with the arguments of the respondent that even if it were considered to be common practice to coat a steel sheet having a zinc alloy with oil after production, none of documents D8, D14, D15 or D16 discloses that a (poly)siloxane layer on a zinc alloy coated steel sheet should be covered by an oil in order to improve adhesive bonding.

6.6.1 The appellant argued that the skilled person is aware that both oil and (poly)siloxane layers can protect from corrosion, so that the use of both layers would improve the anti-corrosion properties further.

6.6.2 In the board's view however this argument is based on knowledge of the invention. Even if the skilled person is aware of the use of oil layers on metal sheets and strips after their production, there is no motivation in the available prior art to provide such a coating on a (poly)siloxane layer.

6.7 The board therefore does not find the arguments of the appellant convincing and is of the view that the subject-matter of claim 1 of the main request is inventive as feature F1.5 is not obvious in view of D13 with D8 or D14 to D16.

7. In view of the above conclusions that the subject-matter of claim 1 of the main request is inventive, it is not necessary to consider the respondent's request to not admit documents D14 to D16 into the appeal proceedings.

8. Conclusion

None of the objections admissibly raised by the appellant prejudices the maintenance of the patent in the amended form found by the opposition division to meet the requirements of the EPC and the appellant has not convincingly demonstrated that the decision under appeal was incorrect.