T 0099/85 (Diagnostic Agent) of 23.10.1986

Summary of Facts and Submissions

I. The respondents are proprietors of European Patent No. 0 016 387 (application No. 80 101 187.5) granted with two claims. The filing date was 8 March 1980. Claim 1 reads: "1. Diagnostic agent for the detection of component materials in liquids, consisting of a water-resistant film which is produced from an aqueous dispersion of film-forming organic synthetic resins and with which are admixed the reagents necessary for the detection, as well as filling materials in the form of insoluble inorganic or organic particles with a size of between 0.2 and 20 micrometres, characterised in that for the opening of the film for component materials with a molecular weight of over 50 000, as well as for component materials in the form of corpuscular components, the weight ratio of the amount of filling material to the amount of synthetic resin lies in the range of from 2:1 to 20:1". Claim 2 is dependent on Claim 1.

II. An opposition filed by the appellants against grant of the patent was rejected by Opposition Division 061 in a decision posted on 22 January 1985.

III. The opponent's appeal, received on 21 March 1985, simultaneously with payment of the appeal fee and together with a statement of grounds, is directed against that decision.

IV. In the oral proceedings which took place on 23 October 1986, the appellants requested cancellation of the contested decision and revocation of European patent 0 016 387. Their submissions were essentially as follows: (a) In view of the decision in appeal case T 198/84, the subject-matter of the granted Claim 1 was no longer novel when compared with the teaching inferable from document DE-A-1 598 153. The stated purpose in the characterising part of the claim "for the opening ..." was in any case not a feature of the agent claimed. Details of the ranges for the particle size and the weight ratio of filler to synthetic resin were not expressly stated in this document but to the person skilled in the art they formed part of its content because quite usual ranges were involved. All other features of Claim 1 were directly inferable from the document. (b) Nor did the aforementioned document and the object stated therein, namely to introduce openings or pores into the layer, indicate that there was any inventive step in using particles of the claimed size and in the claimed weight ratio as filler. It was obvious that openings had to be made, since otherwise there could be no contact between the reagent and the analyte. The claimed solution was suggested by the fact that, on the one hand, in the document cited the introduction of fillers was mentioned and, on the other, the production of pores in synthetic resin films by means of fillers was common knowledge, as documents GB-A-1 316 671, US-A-3 844 865, 3 992 158 and 4 144 306, for example, showed. In particular, the filler (Ti02) in the reagent layer of a diagnostic agent whose weight ratio to the amount of synthetic resin used lay within the claimed range was already known from US-A-4 144 306. The use of fillers in the case of reagent layers for analytes of high molecular weight (e.g. alpha-amylase) was also known from this document. The wide range claimed for the particle size lay within that customary for filler particles.

V. The respondents (proprietors of the patent) request that

1. The appeal be rejected (main request);

2. The patent be maintained in the form submitted by letter of 19 September 1986, received on 23 September 1986, with the proviso that in line 6 of the single claim the words "or organic" be added after "inorganic" (subsidiary request I);

3. The patent be maintained unchanged or with the amendment requested in subsidiary request I and insertion of the supplement to the description received on 23 September 1986 (subsidiary request II). The grounds stated are essentially as follows: (a) The problem should not be seen as how to produce pores or openings in the diagnostic agent known from DE-A-1 598 153; this is already a part of the solution. Starting out from the aforementioned document, the problem is to be seen as how, in the simplest possible way, to make the known agent additionally usable for the analysis of component materials with a high molecular weight. There was no suggestion at all of making any openings for this purpose. There were also other possibilities, such as selection of special film-forming synthetic resins or use of dissolved instead of dispersed synthetic resins. Nor was it to have been expected that the introduction of openings or pores would lead to the desired result. In addition, the particularly simple way of producing the porosity was not suggested by the documents cited by the appellants. In the subject-matter of GB-A-1 316 671 and US-A-3 844 865, the porosity would only be produced by an additional processing step (stretching). According to US-A-3 992 158 and 4 144 306, fillers were introduced only in the spreading layer of a multi-layer diagnostic agent, whereas the reagent layer consisted of water-soluble substances able to swell. (b) The subject-matter of the contested patent was novel, because DE-A-1 598 153 contained no details of range either for the particle size or for the weight ratio, and in US-A-3 992 158 and 4 144 306 the reagent layer was not made from an aqueous dispersion of a filmforming synthetic resin, the reagents being in fact dispersed in the layer-forming synthetic resin. (d) Finally, DE-A-1 598 153 had been published almost ten years before the priority date of the disputed patent and the quantities of fillers specified in the examples it gave lay well outside the range claimed in the disputed patent.

VI. To explain the production and construction of a film from the aqueous dispersion of film-forming organic synthetic resins, the respondents referred to the following bibliography: Polymer News, Vol. 3, Issue 4, 1977, pp. 194-203 "LATEX FILM FORMATION", in particular Figure 10, and "Film-Forming Compositions", Vol. 1, Part 1, 1967, pp. 5-8, in particular Figure 1-2.

Reasons for the Decision

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

2.The subject-matter of Claim 1 in accordance with the main request, i.e. in the granted version of the patent, is novel.

2.1 A diagnostic agent for the detection of component materials in liquids is known from DE-A-1 598 153; it consists of a liquid-resistant film made from an aqueous dispersion of film-forming organic synthetic resins (page 2, second paragraph). To this film are admixed the reagents and fillers in the form of insoluble inorganic or organic particles which are needed for said detection (page 2, last paragraph). Unlike Claim 1, this document does not contain any details of particle size, and the weight ratios of filler to synthetic resin cannot be derived from this document either.

2.2 The appellants' statement according to which the ranges claimed for particle size and weight ratios formed part of the content of DE-A-1 598 153 in view of Appeal Decision T 198/84 is mistaken. That Decision said that a different definition of an invention was not sufficient to guarantee the latter's novelty. However, as the reference to the earlier decision T 12/81 (Official Journal EPO 8/1982,

p. 301) in T 198/84 shows, the intent was to confirm that an object known in itself cannot lead to a new invention by being described in another way, for example by defining a material by its method of manufacture instead of by its structural formula. This is not the case here, however: all reference to specific features of the subject-matter now claimed, namely particle size and weight ratios, is lacking in the earlier document. If these are now specified in the disputed patent, it is not a question of something known being described in different words but the addition of new information which is not provided for the person skilled in the art by the contents of the earlier document. For in principle use is also made of fillers whose particle size lies outside the claimed range, and of synthetic resin films in which the weight ratio of filler to synthetic resin lies outside the range claimed. Thus, for example, US-A-3 844 865 (column 8, lines 31 to 35) teaches that in order to manufacture porous films by stretching, fillers may in principle be used whose particles can be up to 30 µ (for micro-porous films) in size. Similarly, in such a case the proportion of filler in the film as a whole (according to example 2) can amount to 61% by weight, i.e. a weight ratio of filler to synthetic resin of about 1.56:1 is possible. There can therefore be no question of the ranges for particle size and weight ratio stated in Claim 1 of the disputed patent being already implicitly described in DE-A-1 598 153 for the person skilled in the art. DE-A-1 598 153 therefore does not anticipate the subject- matter of Claim 1 so as to be prejudicial to novelty.

2.3 A diagnostic agent for the detection of component materials in liquids is known from US-A-4 144 306 (example 5). This consists of a film containing the reagents needed for detection (cellulose acetate with a bilirubin-active complex). In addition, fillers in the form of insoluble inorganic particles (Ti02) are admixed. The weight ratio of filler to synthetic resin is about 7.7:1 and therefore lies within the claimed range. Unlike the subject-matter of Claim 1, a liquid-resistant film made from an aqueous dispersion of film-forming organic synthetic resins is not involved here. Moreover, nothing about the particle size of the filler can be ascertained from this document.

2.4 Nor can the claimed ranges for particle size and weight ratios of filler to synthetic resins be derived from any of the other documents in the proceedings. The subject-matter of Claim 1 is therefore novel.

3.The subject-matter of Claim 1 according to the main request is also based on inventive step.

3.1 DE-A-1 598 153 comes closest to the subject-matter of the application. From it a diagnostic agent is known which is made from a liquid-resistant film, production thereof being effected either from a solution or from a dispersion of film-forming organic synthetic resins. The necessary reagents and fillers are mixed in with the film, which is suitable for the detection of relatively low-molecular-weight components of liquids (glycose, for example). These films cannot be used however when component materials are to be analysed which consist of large molecules such as enzymes or of corpuscular components. Contrary to the appellants' argument, the problem forming the basis of the disputed patent is therefore not to make "openings" or pores in the reagent layer, but rather to alter the known agent in such a way that component materials with a molecular weight of over 50 000 and those in the form of corpuscular components can also be analysed. This problem is solved by admixing into the film fillers between 0.2 and 20 micrometres in size, in a quantity such that the weight ratio of filler to synthetic resin lies between 2:1 and 20:1.

3.2 It cannot be considered obvious that the problem actually forming the basis of the disputed patent can only be solved by making the film "open", or in other words porous. For one thing, various ways of solving the problem posed present themselves to the person skilled in the art. For example, there is the possibility of picking out from among the film-forming organic synthetic resins those into which larger molecules can also diffuse or those which are "bitten" or swollen by the liquid under investigation. Moreover, on the date of filing it was not to be expected from the outset that, just by opening up the film, the admixed reagents could react with the high-molecular-weight components. Since opening of the film first of all leads only to an increase in its surface, it would have been expected that the known component materials with a low molecular weight would be able to react to a greater extent and possibly more quickly, but not that components which previously could not penetrate the surface at all and lead to a reaction would now react; the prerequisite was that, of the two possibilities for production of the diagnostic agent described in DE-A-1 598 153, the one specifically chosen was the one based on an aqueous dispersion of the film-forming synthetic resin. In the case in point the very realisation that, with a film made from an aqueous dispersion of film-forming organic synthetic resins, just by opening the film a reaction with components of a substantially higher molecular weight is possible than if the film is not "opened", may be regarded as an inventive step (compare also T 229/85 - OJ EPO 1987, 237).

3.3 Moreover, the documents specified do not give any indication that the necessary porosity ("opening") can be achieved just through appropriate selection of particle size and weight ratio of filler to synthetic resin. From US-PS 4 144 306 a diagnostic agent is indeed known in which a filler is used in a quantity lying within the range claimed. Any indication that this filler is to serve to open up the film is lacking, however. The filler is evidently used only to change the optical properties of the diagnostic agent, for with the known agent the porosity is achieved by making the synthetic resin itself in the form of a blush polymer. Documents US-A-3 992 158 (column 7, lines 8-43) and US-A-4 144 306 (column 21, line 54 to column 22, line 12) do in fact mention that porous layers can be produced using fillers. But what is involved here is not the films containing the reagents but additional layers intended to ensure even spreading of the liquid under investigation before the liquid reaches the reagent layer. There is no suggestion of using this measure in a reagent layer in order to allow the liquid under investigation to react with high-molecular-weight components. In any case, these documents also contain no reference to the particle sizes to be used or to the weight ratios of filler to synthetic resin. Still less can US-A-3 844 865 and GB-A-1 316 671 suggest opening up the film defined in Claim 1 by adding fillers in the size and weight ratio range claimed; all these documents are concerned with synthetic resin films which have to be stretched once the fillers have been added in order to make them porous. The documents introduced into the proceedings by the respondents ("LATEX FILM FORMATION", loc. cit., and "Film-Forming Compositions", loc. cit.) give no indication either that it can be appropriate to make films produced from an aqueous dispersion of film-forming organic synthetic resins porous in order to be able to use them to detect high-molecular-weight components of liquids, or that such porosity can be achieved simply by adding fillers with a particle size lying in a specific range and in a specific weight ratio. The subject-matter of Claim 1 is therefore not disclosed in an obvious way from the prior state of the art.

4.In establishing the novelty of the subject-matter of the disputed patent it was indeed shown that the feature stated in the opening part of Claim 1 "(particles) with a size of between 0.2 and 20 micrometres" does not, as the appellants claim, belong to the state of the art (according to DE-A-1 598 153) in conjunction with the other features in the preamble. Nevertheless, the Board sees no reason for it solely on this account, to insist, that the wording of a patent claim already granted should be amended. The Board takes Rule 29(1) EPC for what it is - an implementing regulation, primarily relevant to the patent grant procedure and therefore no more constituting a ground for opposition than for example Article 84 EPC (reference to T 23/86 of 25 August 1986, OJ EPO 1987, 316). Claim 1 can therefore be maintained in the text as granted.

5.The existing Claim 2 according to the main request is dependent on Claim 1 and adds an appropriate further development of its subject-matter. It can therefore likewise be maintained.

6.Since the documents newly introduced into the proceedings have given no cause to restrict the patent claims, it is not necessary to mention them in the introduction to the description.

7.The respondents' main request can therefore be allowed. Their subsidiary requests I and II are thus of no relevance.

ORDER

For these reasons, it is decided that:

The appeal is rejected.