T 0184/82 (Poly (p-methylstyrene) articles) of 4.1.1984

Summary of Facts and Submissions

I. European patent application 79 301 891.2 filed on 14 September 1979 and published on 2 April 1980 with publication number 9377 claiming priority of the prior applications of 18 September and 16 November 1978 (US-943 416 and 961 353), was refused by the decision of the Examining Division of the European Patent Office dated 14 July 1982. The decision was based on claims 1 to 7. The main claim was worded as follows: "A thermoformed shaped article of unitary or laminar structure consisting of or containing at least one layer of a p-methylstyrene homopolymer or of a copolymer thereof with from 1 to 10 weight percent of a conjugated diene, irradiated with between 300 and 700 kGy of ionizing radiation."

II. The reason given for the refusal was that the subject- matter of Claim 1 did not involve an inventive step. The cited publication, US-2 989 452, disclosed the irradiation of mixtures of polystyrene and of a derivative thereof which has an aliphatic substituent attached to an aryl nucleus. The properties with regard to heat and solvent resistance were improved in view of the cross- linking effected by the irradiation. Small amounts of the derivative were sufficient for the purpose and the aliphatic-substituted materials include p-methylstyrene units. The teaching of the document suggested for the skilled man that it would be worthwhile to try the irradiation of the known poly(p-methylstyrene) containers to improve their properties.

III. The applicants lodged an appeal against the decision of 14 July 1982 on 26 August 1982 with payment of the fee, and filed a statement setting out the grounds of appeal on 15 November 1982.

IV. In reply to the objections of the Board the appellant submitted further arguments and amended one of the subsidiary claims. The grounds for the appeal and some of the relevant submissions are essentially as follows: ... c) Although references to various poly-methylstyrenes in US-A-2 893 877 suggest that polystyrene may be well replaced in food packaging materials by such materials, there is no indication that irradiation would selectively improve poly(para-methylstyrene). Evidence submitted with the appeal statement should support the unexpected superiority of the choice. Since the "hot bacon" test is unreliable and the cited art "contains no qualitative or quantitative data which would be necessary to enable the applicants to compare the materials of the invention with the prior art materials under the terms of the prior art" the standard tests to be used should be those for softening points (Vicat) and solubility (in toluene, at room temperature).

V. The appellants requested that the decision under appeal be set aside and the patent be granted. A refund of the appeal fee under Rule 67 EPC was also requested.

Reasons for the Decision

1. The appeal complies with Articles 106 to 108 and Rule 64 EPC, and is therefore admissible.

2. There can be no formal objection to the claims submitted by the applicant with the letter of 30 March 1982 and by the appellant with letter of 13 September 1983, since all features of the claims find support in the application as filed.

3. The problem with which the claimed articles were originally concerned was the need to have containers for food which would resist hot fats. The articles according to the claims should have therefore been capable of holding fat, e.g. in the form of bacon, when exposed to heat in a microwave oven and be substantially undamaged by the treatment. It was suggested that this was achieved by shaping the material consisting of or containing at least 90% poly(p-methylstyrene) irradiated with a certain dose of ionising radiation. The examples of the specification rely appropriately on tests with bacon in a microwave oven to demonstrate the effect and show dramatic differences depending on the constitution of the container and on whether or not the same was irradiated. The appellant, however, has rejected the idea of comparative tests with the relevant state of the art on the same basis and stated that the "hot bacon test ... cannot be relied upon to yield reproducible results" in view of the variability of bacon. Instead, they wished simply to use standard tests for some relevant properties, such as heat resilience (i.e. Vicat temperature) and solubility in toluene, as these were allegedly correlated with the properties upon which they "relied for the invention".

4.It has already been well established through a number of decisions of the Board of Appeal that the statement of the problem, and the associated effect which follows from the use of the claimed invention, is an essential aspect of the assessment of the inventive step (cf. "Carbonless copying paper/Bayer" T 01/80, OJ (EPO) 7/1981, p. 206). The nature of the problem should be determined on the basis of objective criteria. This requires the assessment of the technical success vis-à-vis the state of the closest art (cf. "Aryloxybenzaldehydes/ Shell" T 20/81, OJ (EPO) 6/1982, p. 217). Since the technical effect provided by the invention must represent a result, which is testable and as such reproducible, the admission on behalf of the appellant that the hot bacon test is unreliable casts doubt on the general validity of the corresponding statements in the specification and examples, which suggest that the specific problem has been successfully solved by the invention.

5. Nevertheless, the person skilled in the relevant art would have recognised that the original problem was not unrelated to the more general aim of improving the heat and solvent resistance of materials for containers, since contact with hot bacon probably also means durability at elevated temperatures and better hydrophobic characteristics. Thus improvements in these respects could still be construed as being embraced by the generalised teaching of the original disclosure, and unexpected capabilities may be accepted as indicative of the inventive step even if the more ambitious goals have not been fully or reliably achieved. It was suggested in an earlier decision by the Board that a restatement of the problem may be possible during the course of an appeal (Ibid, T 01/80) under certain circumstances. It is now the opinion of the Board that success at a more general level could replace failure at a specific level regarding the effect of the invention, provided the skilled man could recognise the same as implied or related to the problem initially suggested. The remainder of the decision concerns the state of the art and the evidence presented in support of the appeal, and concluded that the claimed subject-matter does not involve an inventive step.

ORDER

For these reasons, It is decided that:

The appeal against the Decision of the Examining Division of the European Patent Office dated 14 July 1982 is rejected.