T 0666/15 13-08-2018

First auxiliary request

1. The main request having been withdrawn, the first auxiliary request is the highest-ranking request on file.

2. Inventive step

2.1 The invention claimed in the opposed patent relates to a chewing gum composition having a gum base containing a styrene-diene block copolymer. According to what is reported in paragraph [0007] of the patent, styrene-diene block polymers are particularly suitable for manufacturing the gum base of chewing gums. The advantages associated with the use of the specified block copolymers, as opposed to random styrene diene copolymers for example, are believed to stem from their ability to behave like a cross-linked elastic rubber at room temperature and as a thermoplastic at a higher temperature (paragraph [0015]). The patent reports the preparation of different gum bases and chewing gums comprising styrene-diene block copolymers in paragraphs [0051-0060].

2.2 Like the opposed patent, document D2 relates to the preparation of a chewing gum composition and discusses the challenges associated with the manufacture of gum bases comprising styrene-butadiene random copolymers. In column 2, lines 32-37, D2 states that bubble gum bases from styrene-butadiene (random) copolymers are difficult to process because they are sticky, stringy and too elastic. In order to improve their processing, as well as the quality and initial chew characteristics, D2 proposes blending the styrene-butadiene gum base with a polyisobutylene gum base (column 2, lines 50-62; claims; examples).

2.3 The board concurs with both parties that D2 is the closest state of the art to start from in the assessment of inventive step, since it addresses, like the opposed patent, the problems associated with the manufacture of chewing gums having a gum base comprising styrene-butadiene random copolymers. The use of styrene-butadiene block copolymers is not mentioned in D2.

2.4 The experimental section of the patent describes the preparation of gum bases comprising styrene-butadiene block copolymers and comparative formulations comprising styrene-butadiene random copolymers. As reported in paragraphs [0053-0058], chewing gums can be manufactured effectively using the block copolymers. These chewing gums have an adequate chewing profile and in some cases also an excellent bubble capacity. The tested gums and chewing gums contain only one elastomer, namely a styrene-diene block copolymer. It is plausible, however, to assume that similar results would be obtained if, as requested in the claims, a minor amount of a second elastomer were present in the composition.

2.5 Starting from the teaching of D2 as the closest prior art, and taking into account the results presented in the patent, the underlying objective technical problem can be seen as the provision of a further gum base and of a chewing gum comprising said base which has adequate chewing properties, and the provision of a process for manufacturing said products in an effective manner.

2.6 In this context it is worth noting that there is no technical evidence on file confirming that, as stated by the respondent, the use of block copolymers, rather than random copolymers, is associated with an improvement in the processing properties of the gum base. Paragraph [0053] reports a decrease in mixing time, but also concedes that the block and the random polymers were added in different forms (pellets or blocks) and that the effect of this difference is still to be quantified. Moreover, the patent does not report any test comparing products prepared using styrene-butadiene block copolymers with the products described in the closest prior art document D2. For these reasons, the technical problem is to be formulated as the provision of an alternative (i.e. further), rather than an improved, product and/or method for manufacturing said product.

2.7 The question to be answered is whether the skilled person, confronted with the underlying technical problem, would have considered replacing entirely, or at least to a large extent, the random copolymers used to manufacture the gum bases disclosed in D2 with styrene-diene block copolymers.

2.8 D2 itself does not mention styrene-diene block copolymers. However, according to the appellant, the skilled person would have considered using these polymers, taking into account the teaching of documents D4 and D5.

2.9 D5 is an extract from an encyclopedia of polymer science dealing with block polymers having thermoplastic elastomeric properties. Table 13 lists, among other block polymers, styrene-diene copolymers. These are said to be thermoplastic elastomers which can be used to produce moulded products such as adhesives, films, footwear, gaskets, cable insulations: see page 398 Table 13, column "Typical applications", and page 399, last full paragraph. D5 further teaches that the primary advantages of thermoplastic elastomers include easy processing with standard thermoplastic equipment, low processing costs and a "large variety of thermal, rheological and mechanical properties".

2.10 These statements are of a very general nature. In particular, D5 is completely silent as far as the manufacture of a chewable product is concerned. The board concurs with the respondent that, relying on D5, the skilled person would not be able to predict the suitability of styrene-diene block copolymers for the manufacturing of a gum base, let alone predict the chewability of a chewing gum comprising said base. As noted by the respondent, the gum base present in a chewing gum must conform to the teeth when chewed and be easily stretched, torn apart and reformed repeatedly. Products having these properties are not mentioned in D5. Thus, this document would not provide the skilled person with any hint on how to solve the technical problem underlying the claimed invention.

2.11 D4 describes chewing gums comprising polymeric beads having microporous passages impregnated with an active agent, e.g. a sweetener or a flavour. The beads are so designed as to control the release of the active ingredient. The chewing gum described in example VI contains beads comprising styrene-butadiene block copolymers. These beads are said to be crack-resistant. According to the appellant, D4 confirmed that the relevant block copolymers possess elastomeric properties and that they can be used in the manufacture of chewing gums. This would then lead the skilled person to use said polymers for manufacturing the gum base of a chewing gum.

2.12 The board cannot accept this argument. The beads described in D4 are crack resistent, but must also maintain their structural integrity during the chewing process, in order to control the release of the active agent contained in them. In this respect, the properties of the material making up the beads differ substantially from those of the gum base of a chewing gum, which have already been mentioned above. It is also noted that the styrene-butadiene block copolymer contained in the beads is cross-linked by a copolymerisation process involving the use of styrene and divinylbenzene monomers. There is no evidence at hand, and it also seems unlikely, that a material made up of a cross-linked polymer can be torn apart and then reformed.

2.13 Furthermore, although the beads described in D4 are dispersed within a gum base, a skilled person would not have considered them to be part of said base, i.e. of the component of a chewing gum giving it chewability. This is confirmed by the introductory part of D4 (column 1, lines 13-15), which acknowledges that a chewing gum includes a "tasteless masticatory chewing gum base" and a non-masticatory component including the active ingredient. The beads described in D4 are mixed with the "masticatory chewing base" but remain dispersed in it, as separate discrete particles. Neither an explicit nor an implicit teaching can be found in D4 that these beads become effectively part of the gum base contributing to the chewability of the chewing gum. For these reasons, document D4 does not provide any information which could be relevant for the skilled person seeking to solve the underlying technical problem.

2.14 For these reasons, the board concludes that, starting from D2 as the closest prior art, the skilled person would not, without hindsight, have taken into consideration the teaching of D4 and/or D5 when confronted with the underlying technical problem. Accordingly, they would not have prepared a gum base and a corresponding chewing gum as described in claims 1-7 and 12. For the same reasons, they would not have carried out a process for making a chewing gum comprising the use of styrene-diene block copolymers as defined in claims 8-11 or used said copolymers in the manner described in claim 13. As a consequence, the subject-matter of the first auxiliary request involves an inventive step.

3. Document D9

3.1 D9 is an excerpt from a textbook which was first mentioned by the respondent in its letter dated 13 July 2018. A copy of this document was only filed during the oral proceedings. According to the respondent, D9 proved that, although many synthetic rubbers were known to the skilled person at the relevant date, only a few were considered suitable for producing a gum base for a chewing gum. The board noted that the letter referred to the first edition of D9, published in 2006, whereas the copy provided at the oral proceedings stemmed from the second edition, published in 2008, which is well after the filing date of the application from which the opposed patent derives. However, it is not possible to determine from D9 alone whether the information disclosed in the second edition was already in the first one. But even if it had been the case, the first edition of D9 was published between the priority date and the filing date of the application for the opposed patent. This raised new questions as to the validity of the priority date and/or which part of D9 could be considered to belong to the state of the art according to Article 54(2) EPC. These issues had not been addressed before, and neither the board nor the appellant could be expected to deal with them at such a late stage of the proceedings. Accordingly, D9 was not admitted into the appeal proceedings under Rule 13(1) RPBA.