T 0002/23 15-01-2025

Main request

1. Inventive step

1.1 The patent in suit concerns a multilayer film endowed with anti-fogging properties and to its use in packaging, especially of products having a high moisture content (paragraph 1). The sealant anti-fogging compositions according to granted claim 1 containing anionic and non-ionic surfactants dispersed in a mixture of amorphous and (semi)crystalline (co)polyesters, when extrusion coated or coextruded to form heat-sealable multilayer packaging films, would overcome the problems of surface migration of the anti-fogging agents usually found with polyester films and guarantee excellent anti-fogging properties (paragraph 14). The patent in suit is therefore in the field of polyester heat-sealable multilayer packaging films for packaging applications.

1.2 The contested decision established that document D2 was the closest prior art document (section 5a). This was not disputed by the parties in appeal (statement of grounds, section I.1, and rejoinder, section 7). The Board does not see any reason to depart from this acknowledgement with respect to D2 as the closest prior art. Indeed D2 is in the same field as the patent since it relates to a coextruded, biaxially oriented, polyester film having a base layer and a heat-sealable layer useful for ready-meals packaging and also to the use of the multilayer polyester film as a lidding film in food packaging operations (paragraph 1).

1.3 D2 concerns in particular a coextruded, biaxially oriented multilayer film comprising a base layer and a heat-sealable layer directly adhered to said base layer, said heat-sealable layer comprising from about 25% to 70% by weight of an amorphous polyester and from 20% to 60% by weight of a "further polyester" (claim 1). Possible further polyesters are defined in paragraph 28 of D2 as polyesters deriving from one or more aliphatic diols, preferably ethylene glycol and/or cyclohexandimethanols, and an aromatic dicarboxylic acid, preferably terephthalic acid. While that passage does not explicitly refer to (semi)crystalline polyesters, the examples of D2 show that (semi)crystalline polyesters are meant in that context.

1.4 Thus, examples I-VI of D2 are multilayered films according to the invention disclosed therein (paragraph 81) based on a heat-sealable layer (Table 1) containing three polymers referred to as CoPolyEst, PETG and EAA. PETG is defined in paragraph 63 as the commercially available polyethylene terephthalate/glycol Eastman EASTAR PETG 6763, an amorphous polyester also used in the examples of the patent in suit itself (Table 1, lines 38-43 on page 11). CoPolyEst is the "further polyester" of D2 further defined in paragraph 64 as the commercially available copolyester Eastman Chemical EASTAPAK COPOLYESTER 9921, also used in the examples of the patent in suit, as (semi)crystalline polyester (Table 1, lines 19-21 on page 11). These polyesters of the examples of D2 are also used in amounts (Films I-III and VI: 25 wt.-% of CoPolyEst and 60 wt.-% PETG; Film IV and V: 45 wt.-% of CoPolyEst and 40 wt.-% PETG) as defined in granted claim 1 (10-85 wt.-% amorphous polyester and 10-85 wt.-% (semi)crystalline polyester). The examples of D2 therefore explicitly point towards a combination of two polyesters in the heat-sealable layer corresponding to the amorphous and (semi)crystalline polyesters of granted claim 1. That fact was also acknowledged by both parties at the oral proceedings before the Board.

1.5 The decision under appeal identified the distinguishing feature of granted claim 1 over D2 as the presence of a combination of an anionic surfactant and a non-ionic surfactant in individual amounts of at least 1% by weight and at least 0.5% by weight respectively in the heat-sealable composition (decision under appeal, section 5b.1). That difference with respect to D2 was not disputed by the parties to the appeal (grounds of appeal, section I.2 and rejoinder, page 5, fourth paragraph). The Board sees no reason to depart from this acknowledgment with respect to the difference over D2.

1.6 It was also not disputed that D2 disclosed, in a generic form, the possible addition of anti-fogging agents to the heat-sealable composition (paragraphs 46-49 of D2). There is, however, in D2 no explicit disclosure of the addition of the specific combination of anti-fogging agents indicated in granted claim 1.

1.7 The opposition division found no evidence of any effect in the patent in suit of the distinguishing feature over D2 (contested decision, paragraph 5c). The opposition division concluded that the problem was the provision of an alternative lidding film with anti-fogging properties (section 5d).

1.8 Examples 1-6 and comparative examples 1-4 of the patent in suit (Tables 2 and 3) show the preparation of heat-set multilayered films through flat coextrusion. The films are said to contain a sealant layer 1, an inner layer 2 and an outer layer 3. Each layer of the exemplified films is defined by its constituents. It is apparent from Tables 1 to 3 that each sealant layer (heat sealant layer 1) of examples 1-6 and comparative examples 2-4 contains, through the use of a masterbatch composition (MB1 or MB2) a mixture of alkyl sulphonate surfactants and non-ionic surfactants in a polyester composition (Table 1, lines 48-56). It was undisputed that examples 1-6 disclosed sealant compositions according to granted claim 1 but it is also apparent that the patent in suit does not provide a comparison of sealant layers that could show an effect resulting from the use of the specific combination of surfactants in their respective amounts as defined in granted claim 1.

1.9 In particular, all but one film, that of comparative example 1, contain a combination of two surfactants according to granted claim 1. In view of this, examples 1-6 and comparative examples 2-4 cannot show an effect over D2. The film of comparative example 1 is based on a sealant layer 1 that does not contain any anti-fogging agent. That film, however, lacks relevance because the compositions of the sealant layer 1 and inner layer 2 are different from those of examples 1-6 and comparative examples 2-4. The film of comparative example 1 therefore differs in more than one feature from the other films disclosed in the patent in suit and as such, it cannot unambiguously show an effect linked to the use of specific surfactants. Besides, it is apparent from the conclusion laid out in paragraph 144 of the patent in suit that the effect of providing optimal anti-fogging properties in the patent in suit is foremost linked to the use of an amorphous (co)polyester and of a (semi)crystalline polyester, with specific weight ratios between the two components. The causality between the selection of the polyester components and the effect laid out in the patent in suit is however irrelevant in view of D2 as it has been established that D2 disclosed the same combination of polyesters in the same amounts as in granted claim 1. In this respect, the patent in suit does also not point to an effect resulting from the distinguishing feature over D2.

1.10 The appellant formulated the problem as the provision of an alternative anti-fogging lidding composition [suitable] for polyester films (grounds of appeal, section I.4). Although the respondent asserted in writing that the examples in the contested patent showed the presence of a surprising technical effect (rejoinder, section 8), at the oral proceedings before the Board, the respondent formulated the problem over D2 as the provision of heat sealable polyester films having anti-fogging properties with a simple and cost effective manufacturing method. The respondent's and the appellant's formulations of the problem are essentially the same, as they are not based on an improvement over D2, but on the provision of further heat-sealable polyester films with anti-fogging properties.

1.11 The formulation by the respondent additionally mentioned a simple and cost effective manufacturing method, in accordance with the problem defined in the patent in suit (paragraph 13). The reference to the method is made in paragraphs 10-12 of the patent in suit in which it is disclosed that the most common approach to impart anti-fogging properties to polyesters films in the prior art was to apply an anti-fogging coating directly to the inner surface of the film (paragraph 10), thereby increasing the costs of production as it required an additional coating step (paragraph 12). That is, however, not relevant in view of D2 as the closest prior art since that document does not disclose the application of an anti-fogging coating in addition to the polyester sealant films but includes any anti-fogging agents in the heat-sealable layer (paragraph 48). The Board concludes that a reference to a simple and cost effective method is therefore not appropriate in the formulation of the problem over D2.

1.12 The problem that can be formulated over D2 is therefore the provision of further heat-sealable polyester films with anti-fogging properties.

1.13 Starting from the closest prior art D2, the question of inventive step is whether a person skilled in the art would have considered using a combination of a1) an anionic surfactant in an amount of at least 1% by weight and a2) a non-ionic surfactant in an amount of at least 0.5% by weight to impart anti-fogging properties to the heat-sealable polyester film of D2.

1.14 Section 5b.3 of the decision concludes that paragraph 49 of D2, which deals with the question of the anti-fogging properties of heat-sealable layers, does not suggest the use of more than one anti-fogging agent. The appellant contested that conclusion (grounds of appeal, page 3, second paragraph).

1.15 Paragraph 49 of D2 discloses that (emphasis added) "suitable anti-fogging agents are for instance non-ionic fluorinated surfactants, like alkylester fluorides, perfluoroalkyl ethyleneoxides, anionic fluorinated surfactants, like quaternary ammonium salt of perfluoroalkyl sulfonates, non-ionic surfactants like polyhydric alcohol fatty acid esters, higher fatty acid amines, higher fatty acid amides, and ethylene oxide adducts of higher fatty acid esters, amines or amides and the like, polyoxyethylene ether of a fatty alcohol, glycerol fatty acid ester, preferably polyhydric alcohol fatty acid ester and their ethoxylated derivatives, more preferably ethoxylated sorbitan derivatives with higher fatty acids such as those marketed under the trade name of Tweens or Polysorbates, preferably with fatty acids from C14 to C24, in particular ethoxylated sorbitan monooleate marketed as Tween 80. The amount of anti-fogging agent added to the heat-sealable layer is generally from 0.5 to 8%, from 1 to 5%, from 1 to 3%, preferably from 0.5% to 2.5% by weight of the heat-sealable layer".

1.16 This passage of D2 clearly refers to the use of anionic fluorinated surfactants as well as non-ionic surfactants as anti-fogging agents in an amount overlapping with the amounts defined in granted claim 1 (at least 1 wt.-% of anionic surfactant and at least 0.5 wt.-% of non-ionic surfactant). In view of this teaching of D2, the Board does not consider that an inventive step can be recognised to granted claim 1 simply because D2 does not explicitly refer to a combination of surfactants. In particular, since anionic fluorinated surfactants and non-ionic surfactants are known from D2 to be anti-fogging agents, the use of a combination of any of these two surfactants merely to provide further compositions with anti-fogging properties is within the ordinary skill of the person skilled in the art. Moreover, the use of the plural (anti-fogging agents) in the first sentence of paragraph 49 of D2 ("To obtain anti-fogging surface anti-fogging agents may be compounded directly into the resins...") clearly does not exclude the option to use multiple anti-fogging agents in combination in particular when simply looking for further compositions.

1.17 Since D2 does not explicitly disclose a combination of anionic fluorinated surfactants and non-ionic surfactants, it does not disclose specific ranges of amounts for each of the two surfactants. However, a person skilled in the art would understand that the range of amounts disclosed in paragraph 49 for the anti-fogging agent (0.5-8 wt.-%) would apply equally to any combination of surfactants overall. The selection, in granted claim 1, of specific amounts of surfactants (at least 1 wt.-% of anionic surfactant and at least 0.5 wt.-% of nonionic surfactant) which fall within the broader range disclosed in D2, in the absence of any effect resulting from that selection, is only an arbitrary selection, which on this basis is not inventive with respect to D2.

1.18 In this respect the Board concurs with the findings in T 1179/16 (reasons 3.4.4), cited by the appellant, that if the only contribution of the invention is to provide an alternative, then it is usually appropriate to consider that the skilled person would take into account any alternative known in the underlying technical field (unless the closest prior art teaches away from it). In such a case, it is not required to justify the selection of a particular solution.

1.19 Granted claim 1 lacks an inventive step in view of D2 alone.

1.20 The appellant also cited the prior art documents D1 and D9 as relevant to the question of inventive step over D2 (grounds of appeal, sections I.5.1 and I.5.2). However, the Board does not consider these documents to be relevant for the following reasons:

1.20.1 D1 relates to co-extruded, laminated polyolefin films (claim 1) which can be used in food packaging and which have simultaneously transparent, antistatic and antifogging properties (paragraph 2). The films of D1 contain, in addition to an olefin resin, a non-ionic surfactant and a salt of an organic sulfonic acid in a total amount of 0.05-3 wt.-% and in a weight ratio of 20/80-99/1 to impart antistatic and antifogging properties to the films (claim 1). D1 does not disclose that the salts of an organic sulfonic acid used in the composition are surfactants. Although some of the salts of an organic sulfonic acid disclosed in paragraph 15 of D1 may be surfactants, as appears to be the case for the components of mixture B-4 used in examples 6 and 8 in Table 1 of D1, which is also cited in granted claim 3 of the patent in suit, it cannot be concluded from this that all salts of organic sulfonic acids are surfactants. Furthermore, D1 refers exclusively to films containing polyolefins (claim 1) and does not refer to films based on other polymers and in particular on polyester compositions of any kind. On this basis, D1 cannot provide any indication to use the two specific kinds of anti-fogging agents in combination in polyesters compositions, even when simply looking for further compositions with anti-fogging properties.

1.20.2 D9 discloses multilayer biaxially oriented polyester films containing a combination of anionic and non-ionic surfactants (claim 1). While D9 appears to disclose the same combination of surfactants as defined in the granted claim 1, D9 only concerns their presence in the composition as antistatic agents and does not mention their anti-fogging properties. Thus, even if the examples of D9 disclose compositions close to those defined in granted claim 1, the skilled person would not have considered D9 relevant in the context of D2 and when aiming at solving the posed problem, since the purpose of D9 is not to provide anti-fogging properties, but to impart antistatic properties which are not even mentioned in D2. The appellant argued that the two properties were known to be related, but no clear evidence of this was provided in the appeal. In this respect, even the teaching of D1, which simply mentions the desire to have both antistatic and anti-fogging properties at the same time (see e.g. paragraphs 2 and 4), does not provide any basis for the equivalence between the two properties, nor any indication that the skilled person would have known from common general knowledge that components known to have antistatic properties are necessarily anti-fogging agents. On this basis, the Board concludes that D9 was not relevant to the present question of inventive step starting from D2 as the closest prior art.

Auxiliary request set A

2. Admittance and inventive step

2.1 The respondent submitted a new set of claims (set A) as auxiliary request with their reply to the statement of grounds of appeal. Claim 1 of that auxiliary request differs from granted claim 1 in that the minimum amounts of components a1) and a2) are raised to at least 1.5% by weight of a1) and at least 0.75% by weight of a2).

2.2 Auxiliary request set A is a new set of claims that was meant to address an attack of lack of inventive step based on D2 in combination with D9, a document filed in opposition proceedings on 17 January 2022, i.e. one day before the oral proceedings before the opposition division (see rejoinder, point 11). It is therefore apparent that the new request was filed as a legitimate reaction to the late submission of D9.

2.3 Under these circumstances the Board finds it appropriate to exercise its discretion under Article 12(4) RPBA by admitting auxiliary request set A into the appeal proceedings.

2.4 The patent proprietor indicated that the changes made in the quantities of surfactants in operative claim 1 resulted in a claim that was closer to and more representative of the examples of the patent in suit. Since the examples of the patent in suit were found not to be relevant to the issue of inventive step for reasons not related to the amounts of surfactants in the composition (see points 1.8 and 1.9, above), the Board concludes that the patent in suit does not support the presence of an effect for operative claim 1. The respondent also did not argue that operative claim 1 resulted in any other effect with respect to claim 1 as granted.

2.5 The Board therefore finds that the problem formulated for the main request, namely the provision of further heat-sealable polyester films with anti-fogging properties, also applies to operative claim 1. Since the ranges of amounts defined in operative claim 1 are also encompassed by the range of anti-fogging agent disclosed in paragraph 49 of D2, the Board does not see any reason to come for auxiliary request A to a conclusion on inventive step different from the one reached for the main request. On this basis, also claim 1 of auxiliary request set A does not involve an inventive step over D2.

Auxiliary request set B

3. Admittance and inventive step

3.1 The respondent submitted a new set of claims (set B) as auxiliary request with their letter of 13 December 2024. Claim 1 of that auxiliary request differs from granted claim 1 in that the "anionic surfactant a1) is selected from the group consisting of alkylsulphates, preferably sodium lauryl sulfate, 2-ethylhexylsulfate; polyoxyethylene alkyl ether acetates; alkylsulphonates, preferably sodium dodecylbenenesulfonate; alkyl-aryl phosphates; ether-phosphates; higher alcohol phosphate esters; higher alcohol ethylene oxide adduct phosphate esters, and acyl-N-methyltaurin; carboxylates; sulfosuccinates; alkyl ether sulfonic acids; linear benzenesulfonic acids; olefinsulfonic; dialkylsulfosuccinic acids, arylsufuric acids; esters of polyoxyethylenealkylphenyl ethersulfuric acids, preferably it is an alkylsulfonate".

3.2 Auxiliary request set B was submitted after the issuance of the preliminary opinion of the Board, expressed in the communication under Article 15(1) RPBA dated 5 November 2024, and one month before the oral proceedings before the Board. The respondent argued that the amendment in operative claim 1 was made in response to the preliminary opinion of the Board as set out in section 7.11 of said communication that a skilled person could combine anionic surfactant and non-ionic surfactants as anti-fogging agents in the claimed amounts in view of the teaching of paragraph 49 of D2 alone.

3.3 It is indeed apparent that the reasoning on inventive step set out in the statement of grounds of appeal, while it started from D2 as the closest prior art, exclusively relied on a combination with documents D1 or D9 to arrive at a conclusion of lack of inventive step of granted claim 1 (statement of grounds of appeal, sections I.5.1 and I.5.2). While the preliminary opinion of the Board was mainly based on paragraph 49 of D2 which was amply discussed in the decision under appeal (point 5b in the reasons) and by the appellant in appeal (points I.2 and I.5.2, first full paragraph on page 6, of the statement of grounds of the appellant), it shed a new light on the analysis of inventive step by drawing a preliminary conclusion that there was lack of inventive step on the basis on document D2 alone, while considering unsuccessful the attacks of the appellant based on the combination with D1 or D9. On this basis, the Board sees the presence of exceptional circumstances which justify the reaction of the respondent and the filing of a further set of claims after the communication addressing inventive step based on D2 alone. Under these circumstances, the Board finds it appropriate to admit auxiliary request set B into the appeal proceedings (Article 13(2) RPBA).

3.4 It was undisputed that claim 1 of auxiliary request set B additionally differed from D2 in the selection of the anionic surfactant a1) among a list of options which are not mentioned in paragraph 49 of D2. The limitation of the anionic surfactant a1) according to operative claim 1 was not associated with any new effect over D2. The problem defined for the main request, namely the provision of further heat-sealable polyester films with anti-fogging properties, is therefore also valid for claim 1 of auxiliary request set B.

3.5 Paragraph 49 of D2 contains a list of anti-fogging agents among which the only anionic surfactants are anionic fluorinated surfactants, like quaternary ammonium salt of perfluoroalkylsulfonates. There is no further teaching in D2 from which it could be concluded that anionic fluorinated surfactants could be replaced by any of the anionic surfactants defined in operative claim 1. The appellant argued at the oral proceedings before the Board that the presence of fluorine atoms on the anionic surfactant was irrelevant and would not change the question of inventive step over D2. Evidence that a skilled person would consider any of the specific anionic surfactants listed in operative claim 1 in place of the anionic fluorinated surfactants mentioned in D2 was however not provided. It follows that the Board cannot conclude on the basis of the prior art provided that a skilled reader of D2 would have considered using any of the anionic surfactants listed in claim 1 of auxiliary request set B in place of the anionic fluorinated surfactants disclosed in D2.

3.6 The Board can therefore only conclude that on the basis of the evidence provided it was not shown that the composition of claim 1 of auxiliary request set B lacks an inventive step over D2 alone. As the attacks based on a combination of D2 with either D1 or D9 do not lead to the subject-matter of claim 1 for the reasons detailed for the main request (see point 1.19, above), the objection of lack of inventive step of the appellant is unsuccessful.