T 0019/81 (Film coating) of 29.7.1981

Summary of Facts and Submissions

I. European patent application No. 78 100 869.3, filed on 12 September 1978, published on 13 June 1979 and claiming priority from 29 November 1977 in respect of an application in the Federal Republic of Germany, was refused by decision of Examining Division 093 of the European Patent Office dated 1 April 1981. This decision was taken on the basis of patent claims 1 to 5 for a process and for an apparatus to carry out this process filed on 14 November 1980. The first process claim and the first apparatus claim read as follows: "1. Process for producing a film-coated tubular plastics extrusion by extruding the resin in a thermosplastic condition, applying a film to the thermoplastic extrudate after its emergence from the extruder and passing the film-coated extrudate through a sizing sleeve, characterised in that the film is brought into contact with the tubular extrudate at the entrance of the sizing sleeve and entrained with the latter into the sizing sleeve, where the tubular extrudate is constrained against the inner wall of the sizing sleeve by means of a partial vacuum therein and cooled to a temperature below its softening point 4. Apparatus to carry out the process described in claims 1 to 3, consisting of an extruder fitted with an extrusion nozzle(1) and a sizing sleeve(2), characterised in that between the nozzle(1) and the entrance of the sizing sleeve(2) there is a narrow annular slit(6) for insertion of the film and that the sizing sleeve is designed for vacuum operation." The text of the remaining claims may be seen from the file.

II. The stated grounds for the refusal were that neither the subject-matters of claims 1 and 4 nor the subject-matters of claims seeking to combine the features listed in claim 1 and/or 4 and one of the dependent claims involved an inventive step. In support of its decision, the Examining Division argued amongst other things that German examined application No. 1 193 666 already contained the teaching that in a process for producing a coated tubular extrusion, the sizing sleeve setting the final shape of the end product could also be used for bonding the coating to the tubular extrudate. It was obvious to a person skilled in the art to make use of this teaching in the process described in German unexamined application No. 2 605 466 for the purpose of avoiding an extra process stage for bonding the outer coating to the tube. Bringing the film into contact with the tube right at the entrance to the sizing sleeve was obvious from German unexamined application No. 2 312 541 in the same field. The fact that in the present application the outward constraint towards the sizing sleeve was achieved by external suction rather than internal pressure in no way affected the obviousness of the subject-matter of claim 1. This step was not inventive as it was familiar to a person skilled in the art. Claim 1 could not therefore be allowed. As to the insertion of a lubricant between the inner wall of the sizing sleeve and the tubular extrudate (claim 3), the applicant was referred to US patent specifications 2 512 844 and 2 597 553. The routine constructional arrangements given in claim 4 were also known, partly from German unexamined application No. 2 312 541 and partly from German examined application No. 1 162 067. Combining them was obvious. Claim 4 relating to an apparatus to carry out the process described in the application could thus not be allowed either.

III. On 27 May 1981, the applicant lodged an appeal against this decision, at the same time paying the fee and filing the Statement of Grounds. The applicant argued that the Examining Division's attitude when examining the obviousness of the method in claim 1 was at odds with the views of those skilled in the art. This was shown by British patent specification 1 383 923, where the inventor of the process described therein - a process very similar to the one in the present application - expressed the view that the hollow extrudate could not maintain itself in the vacuum sizing sleeve if the negative pressure did not act directly upon the surface of the hollow extrudate. In view of the teaching of British patent specification No. 1 383 923, the fact that in the present application the hollow extrudate did maintain itself in the sizing sleeve was a surprising effect. The applicant requested that the contested decision be set aside and a European patent be granted.

Reasons for the Decision

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

2. The applicant maintains unchanged claims 1 to 5 underlying the decision to refuse the application. These claims are supported by the contents of the original documents and thus cannot be faulted on that score.

3. The process outlined in claim 1 is clearly intended to solve the problem of avoiding application of the film involving additional pressure-generating apparatus.

4. Of the patent documents supporting the contested decision, only the German unexamined application No. 2 605 466 relates to a process for producing a film-coated plastics tubular extrusion by extruding the resin in a thermoplastic condition and feeding the film-coated tubular extrudate through a sizing sleeve. The process in claim 1 in its current form differs from this known process for one thing in that the film is made to contact the hollow extrudate only at the entrance of the sizing sleeve. Nor is this feature used in the process for producing a film-coated plastics tubular extrusion by extruding the resin in a thermoplastic condition, as described in the German unexamined application No. 2 337 677 which, while not cited by the Examining Division, was however mentioned in the original description and in the search report. The process described in claim 1 is thus new vis-à-vis the known state of the art.

5. It thus remains to be examined whether this process involves an inventive step.

5.1 The applicant's view is that in the contested decision this question was answered in the negative by taking an approach which may at first sight appear convincing but which does not accord with the views of those skilled in the art. The applicant bases this assertion on British patent specification No. 1 383 923, lines 21 to 37 on page 2 of which, he claims, indicate that a person skilled in the art was of the opinion prior to the claimed date of priority that the hollow extrudate could not maintain itself in the sizing sleeve, and would therefore collapse, if the negative pressure were not exerted directly on the surface of the extrudate. In view of this teaching, the result of the process as described in claim 1 had to be regarded as surprising.

5.2 The above-mentioned part of British patent specification No. 1 383 923 contains the information that the strip entrained with the hollow extrudate must, if it covers one or more sides of the hollow extrudate, be made of an air-pervious material to prevent a substantial decrease of the effect of the vacuum in the sleeve. The patent specification does not explain why an air-impervious strip would have this detrimental effect.

5.3 The Board is unable to accept the argument that this information reflects the views of those skilled in the art on the question of the effect of a vacuum applied to a sizing sleeve on a film-coated hollow extrudate passing through the sleeve. This assertion is merely the opinion of the drafter of the patent specification, and may be based on special conditions of the proposed process which were not mentioned in the British patent specification. In the absence of corroborating evidence, the assertion thus cannot be accorded general validity. Nor therefore can it lead to the conclusion that those skilled in the art were labouring under the misapprehension that, if a vacuum were applied to the sizing sleeve used in the process described in German unexamined application No. 2 605 466, the hollow extrudate would not be forced against the sizing sleeve's interior wall together with the film, because of the latter's air-imperviousness, and that the applicant has therefore disabused those skilled in the art of a misconception. The effect of the vacuum described as surprising by the applicant was in fact to be expected by a person skilled in the art. For his stock of knowledge would tell him that, if a vacuum is applied to a chamber surrounding a closed tubular body consisting of two nested layers, then the walls of the tube, if sufficiently deformable, are forced against the walls of the chamber by the relatively higher pressure obtaining inside the tube. The fact that in the application in question both layers moved together thus merely confirmed the theoretical expectations of a person skilled in the art. But even if a person skilled in the art had, upon reading British patent specification No. 1 383 923, come to question the correctness of his assumption that both layers would move together against the sizing chamber when a vacuum was applied, he would have been able to ascertain by simple experimentation whether these doubts were justified. In this respect the application thus contains nothing other than was to be expected.

5.4 No other reasons suggesting that the differential pressure used to shape the tube by forcing it against the sizing chamber wall (see German examined application No. 1 193 666) is not also suitable for joining the film to the tubular extrudate and that this pressure could not be produced by applying a vacuum - already known to a person skilled in the art as an alternative to an internal positive gauge pressure (German examined application No. 1 162 067) - have been supplied by the applicant or are otherwise apparent. German examined application No. 1 193 666, in particular claims 5 and 6, had in fact already informed those skilled in the art that the pressure in the sizing sleeve suffices to achieve an adequate bond between a hollow extrudate and a film surrounding it.

5.5 Nor does the further feature mentioned in claim 1, i.e. that the film is brought into contact with the tubular extrudate at the entrance of the sizing sleeve, constitute an inventive step, since it is in fact a precondition for forcing the tubular body consisting of hollow extrudate and film against the interior wall of the chamber.

5.6 The process outlined in claim 1 thus does not involve an inventive step (Article 56 EPC). Claim 1 therefore cannot be allowed under Article 52(1) EPC.

6. Claims 2 and 3 are dependent on the unallowable claim 1 and therefore fail with the latter.

7. The applicant has not replied to the comments in the contested decision denying the allowability of claim 4 relating to an apparatus. After conducting its own examination, the Board has come to the conclusion of the Examining Division that the features outlined in this claim are known partly from German unexamined application No. 2 312 541 and partly from German examined application No. 1 162 067 and that combining them does not exceed what may be required from a person skilled in the art, without requiring an inventive step on his part. Claim 4 is thus likewise not allowable.

8. Claim 5, which is based on an extension of the apparatus claimed in claim 4, is thus also not allowable.

ORDER

For these reasons, it is decided that:

The appeal of the applicant is dismissed.