T 0261/03 25-06-2007

Summary of Facts and Submissions

I. The grant of the European patent No. 0 630 938 in the name of GE Plastics Japan Limited, in respect of European patent application No. 94 304 195.4 filed on 10 June 1994 and claiming priority of the Japanese patent application JP 17754193 filed on 25 June 1993 was announced on 1 September 1999 (Bulletin 1999/35) on the basis of 2 claims.

Claims 1 and 2 read as follows:

"1. A resin composition containing (a) 100 parts by weight of a polyphenylene ether resin or a polyphenylene ether resin and a vinyl aromatic hydrocarbon resin; and (b) 0.1-40 parts by weight of an organophosphorus compound of formula I containing 50 ppm by weight or less magnesium as an impurity

FORMULA/TABLE/GRAPHIC

where R**(1)-R**(5) are each selected from the group consisting of C2-12 aliphatic hydrocarbon residues, C6-14 aryl groups, alkyl-substituted aryl groups, aralkyl groups, and corresponding divalent residues, or any of the above groups substituted with a halogen atom, a hydroxy group, an aryl group, or a halogenated aryl group; R**(1) when present in a plurality may be the same or different; two from among R**(1)-R**(5) may bond together to form a ring; R**(1)-R**(5) may be substituted with groups possessing a carbon-carbon unsaturated double bond or triple bond; at least one of R**(1)-R**(5) possesses an aromatic residue; and n is an integer from 1 to 30.

2. A blow molding resin composition according to Claim 1."

II. A Notice of Opposition was filed against the patent by BASF AG on 26 May 2000 in which revocation of the patent on the grounds of lack of novelty and lack of inventive step (Article 100(a) EPC) was requested.

These following documents have been inter alia cited during the opposition proceedings.

Dl: GB-A-2 043 083;

D3: EP-A-0 501 162

D4: EP-A-0 521 628;

D5a JP-A-57-207641;

D5b: English translation of the main claim and listing of the components of D5a;

D5c: Derwent abstract of D5a;

D5d: English translation of Example 3 of D5a;

D6: Houben-Weyl, Methoden der Organischen Chemie, Volume XII/2, 1964, pages 321-325;

D9: Declaration of Dr. Blundell dated 26.5.2000; and

D10: Information sheet Fyrolflex® RDP; dated 1 Nov 98.

III. By a decision announced orally on 16 October 2002 and issued in writing on 2 December 2002, the Opposition Division decided that the grounds of opposition raised by the Opponent did not prejudice the maintenance of the patent in amended form.

The decision of the Opposition Division was based

on a set of Claims 1 to 2 as submitted at the oral proceedings as main request.

Claim 1 of the main request differed from Claim 1 as granted in that the expression "containing 50 ppm by weight or less magnesium as an impurity" had been replaced by the expression "containing magnesium as an impurity in the amount of 50 ppm by weight or less".

Claim 2 corresponded to Claim 2 as granted.

According to the decision, the main request met the requirements of Article 123 EPC, since the amendments made in the new claims were supported by page 3, lines 5 to 6 of the patent in suit and by page 3, lines 31 to 32 of the application as filed.

The subject-matter of the main request was considered as novel over D1 and D5, which disclosed all elements of Claim 1 except the magnesium content of the organophosphorus compound.

According to the decision, D1 or D5 read in combination with document D6 made available compositions in which the phosphate additive did not contain magnesium but there was no explicit or implicit disclosure in these documents of compositions in which the amount of magnesium was limited to below 50 ppm. These documents could not also be combined with any later published documents or with the statements made in D9.

Concerning inventive step, document D1 was considered as the closest state of the art. Starting from D1 the technical problem to be solved was seen in the preparation of compositions based on the teaching of Dl, which can be processed into articles having a satisfactory surface. According to the decision, nothing in the documents cited or in the general knowledge of the skilled worker suggested that the discoloration was related to the presence of residual magnesium in the phosphorus compound. The Opposition Division considered the arguments of the Opponent that a skilled person would link the surface discoloration with catalyst residues in the phosphate and that it would be led to minimise the amount of catalyst residue, as being based on hindsight. According to the decision, even if the link with magnesium would have been found, this would not have necessarily led to the idea of reducing the magnesium content, since document D4 also disclosed phosphates which were entirely free from magnesium.

The Opposition Division did not also accept the further argument of the Opponent that the skilled person putting the teaching of D1 into practice would use the product Fyrolflex® which was commercially available in 1993, and which, according to the Opponent, contained 5 ppm of magnesium, since there was no evidence that there was a quasi "one-way-street" situation and that the magnesium content of Fyrolflex® was below 50 ppm prior to the priority date of the patent in suit.

IV. By a letter received at the EPO on 17 January 2003, ROMIRA GmbH informed the EPO that in view of a transfer of business from BASF AG to DEMI Vertriebs- und Beteiligungsgesellchaft mbH (in the following "DEMI") the status of opponent in the opposition proceedings concerning the European patent No. 0 630 938 had changed to DEMI.

V. A Notice of Appeal was filed on 7 February 2003 by DEMI (Appellant) with simultaneous payment of the prescribed fee.

In the Statement of Grounds of Appeal filed on 9 April 2003, the Appellant argued essentially as follows:

(i) In granted Claim 1, the organophosphorus compound was defined as "containing 50 ppm by weight or less magnesium as an impurity."

(ii) In amended Claim 1, the organophosphorus compound was defined as "containing magnesium as an impurity in the amount of 50 ppm by weight or less".

(iii) According to the decision of the Opposition Division this second expression would exclude compositions in which the organophosphorus compound were free of magnesium and would restore the novelty over D1 and D5.

(iv) The second expression however still encompassed the case where no magnesium was present.

(v) If one would follow the argumentation of the Opposition Division, this would imply that the scope of protection would vary with the improvement of the analytical techniques.

(vi) Such uncertainty would be contrary to Article 84 EPC.

(vii) Furthermore, the formulation of Claim 1 excluding the case where magnesium was missing represented an unallowable extension (Article 123(2) EPC).

VI. With its letter dated 12 June 2003, the Appellant submitted experimental results in order to show that the claimed magnesium content had no influence on the colour stability or on the bleeding of articles molded from PPE compositions. It also submitted the following document:

D15: Fundamentals of Colorimetry.

VII. With its letter dated 15 August 2003, the Respondent (Patent Proprietor) contested the admissibility of the appeal filed by DEMI.

VIII. By an interlocutory decision dated 24 November 2005, the Board decided that the appeal filed by DEMI was admissible.

IX. In a communication of the Board issued on 26 September 2006 and annexed to the summons to oral proceedings scheduled to take place on 24 January 2007, the attention of the Parties was drawn to issues concerning the allowability of Claim 1 of the main request under Article 123(2) EPC, the clarity of Claim 1 of the main request and the interpretation of the claims in view of the limitation of the magnesium content in the organophosphorus component of the claimed composition.

X. With its letter dated 21 December 2006 the Respondent submitted a first, a second and a third auxiliary requests.

The first auxiliary request corresponded to the claims as granted.

Claim 1 of the second auxiliary request read as follows:

"A resin composition containing (a) 100 parts by weight of a polyphenylene ether resin or a polyphenylene ether resin and a vinyl aromatic hydrocarbon resin; and (b) 0.1 to 40 parts by weight of tetraphenyl resorcine bisphosphate containing 2 to 50 ppm by weight of magnesium as impurity."

Claim 2 was directed to a blow molding resin composition according to Claim 1.

Claim 1 of the third auxiliary request read as follows:

"A resin composition consisting essentially of (a) 100 parts by weight of a polyphenylene ether resin or a polyphenylene ether resin and a vinyl aromatic

hydrocarbon resins; and (b) 0.1 to 40 parts by weight of tetraphenyl resorcine bisphosphate containing 2 to 50 ppm by weight of magnesium as impurity."

Claim 2 was directed to a blow molding resin composition according to Claim 1.

The Respondent also argued essentially as follows:

(i) According to the Statement of Grounds of Appeal, the appeal was based on Articles 84 and 123(2) EPC.

(ii) It would appear that the Appellant, in its letter dated 12 June 2003, had also referred to Article 56 EPC. No objection under Article 54 EPC had been raised in the Statement of Grounds of Appeal or in the subsequently filed letter.

(iii) Article 84 EPC was not a ground for opposition. Article 84 might play however a role when the claims had been amended during opposition proceedings.

(iv) The wording present in granted Claim 1, i.e.

"an organophosphorus compound containing 50 ppm by weight or less magnesium as an impurity", had been changed into "an organophosphorus compound containing magnesium as an impurity in the amount of 50 ppm by weight or less."

(v) This formulation had been selected to avoid any misunderstanding i.e. to make the claim clearer. Although the original claims already excluded the possibility that the magnesium content be 0 ppm, this wording made clearer that some magnesium must be present.

(vi) If there was a lack of clarity as alleged by Appellant this would have been also the case in the granted claim. The alleged unclarity had hence not been caused by the amendment.

(vii) Consequently the objection under Article 84 EPC should be disregarded.

(viii) Concerning inventive step:

(viii.1) In its Statement of Grounds of Appeal the Appellant had not raised any objection concerning inventive step.

(viii.2) In its further submissions the Appellant had brought forward a completely new argumentation based on the experimental results presented in its letter dated 12 June 2003.

(viii.3) It was requested not to admit this argument into the procedure since it had been filed late.

(viii.4) This argument was furthermore irrelevant.

(viii.5) The present invention dealt with prevention of bleeding of the organophosphorus compound to the surface, of release of gases and of discoloration during molding of the composition.

(viii.6) The examples of the patent in suit showed that this problem had been solved with the claimed compositions. The data in the patent in suit clearly showed that a composition as claimed had better properties as compared with compositions comprising a phosphorus compound with high magnesium content.

(viii.7) The tests made by the Appellant were totally different since they referred to an artificial ageing and the effect of the ageing on the colour of the sheet has been measured.

(viii.8) These tests had hence nothing to do with the objective of the invention.

XI. In its letter dated 22 December 2006 the Appellant argued essentially as follows:

(i) The objections under Article 123(2) and 84 EPC against the feature "containing magnesium as an impurity in the amount of 50 ppm or less" were based on the interpretation of this feature given by the Patent Proprietor and the Opposition Division according to which the value 0 would be excluded.

(ii) This interpretation was not derivable from the application as originally filed. In the application as originally filed the skilled person was instructed that the content of magnesium should be as low as possible, i.e. at best 0.

(iii) According to this interpretation a certain amount of magnesium would be compulsory in order to obtain the results aimed at.

(iv) This would represent an unallowable extension.

(v) The lower limit of magnesium was not defined. It would furthermore depend on the method used for its determination. Thus, Claim 1 did not meet the requirements of Article 84 EPC.

(vi) If, however, it would be considered that the present wording also encompassed the value 0, document D1 read in combination with D6 would be novelty destroying.

(vii) In any case, if one would consider that the value 0 was excluded, no inventive step could be acknowledged in view of D1.

(viii) The tests submitted with the letter dated 12 June 2003 showed that the improvement of the colour stability was not linked to the magnesium content of the phosphorus compound.

(ix) Furthermore, there was no limitation of the magnesium content of the composition.

(x) The magnesium content of the phosphorus compound was merely arbitrarily chosen in order to achieve a formal limitation over the prior art.

XII. With its letter dated 19 January 2007, the Respondent submitted four additional auxiliary requests as well as the following documents:

D16: Experimental report dated 18 January 2007 concerning the magnesium content of PPE and HIPS samples;

D17: Copy of an E-mail correspondence dated 18 January 2007 between Mr. Kodaira, Tetsuji of GE Indust. Plastics and Mr. Grever, Frederik of GE Indust. Plastics; and;

D18: Relevant pages of attachment to the E-mail correspondence D17 (in Japanese).

XIII. Following cancellation of the oral proceedings scheduled to take place on 24 January 2007, the Board, in a communication issued on 13 March 2007 and annexed to the summons to oral proceedings scheduled to take place on 25 June 2007, drew the attention of the Parties to issues concerning in particular the allowability of Claim 1 of the second, third, fourth, fifth, sixth and seventh auxiliary requests under Article 123(2) EPC, the interpretation of the claims in view of the limitation of the magnesium content in the organophosphorus component of the claimed composition, the interpretation of the tests submitted by the Appellant with its letter dated 12 June 2003, as well as the effect of the amount of magnesium incorporated in the composition by the phosphorus additive.

XIV. With its letter dated 21 May 2007, the Appellant submitted the following documents:

Annex 1: Internet page "Environmental Measurement I: Gas-Solution Analytical Center Practical Detection Limits", and

Annex 2: US-A-4 554 267.

It also argued essentially as follows:

(i) The tests submitted with letter dated 12 June 2003 showed that the magnesium content in the phosphorus additive had no influence on the discoloration of the surface of the molded parts.

(ii) There was no indication in the patent in suit how the magnesium content of the phosphorus additive should be determined. As shown by Annex 1 different methods had different levels of detectability.

(iii) Auxiliary requests 2 to 7 did not meet the requirements of Article 83, 84, and 123(2) EPC.

XV. With its letter dated 25 May 2007, the Respondent submitted a new main request and seven auxiliary requests.

Claims 1 and 2 of the main request corresponded to Claims 1 and 2 of the second auxiliary request submitted with letter dated 21 December 2006.

It also argued essentially as follows:

(i) There was no indication in the patent in suit that the magnesium content was linked to other factors such as the type of PPE, of vinyl aromatic hydrocarbon resin, type of phosphorus additive and relative amounts thereof. Thus, the main request should be allowable.

(ii) Examples 1 and 2 of the patent in suit showed that blow molded articles without discoloration could be obtained when using the phosphate component with 2 and 11 ppm magnesium content.

(iii) The tests submitted by the Appellant could not be compared with these examples. Furthermore, these tests did not relate to blow-molded articles.

(iv) There was no suggestion in the prior art that the discoloration of blow molded articles might be associated with the magnesium content of the phosphorus additive.

XVI. Oral proceedings were held before the Board on 25 June 2007.

At the oral proceedings the discussion firstly focussed essentially (i) on the question of allowability of the main request under Article 123(2) EPC, and (ii) on the question of the determination of the lower limit of magnesium set out in Claim 1 of the main request.

The arguments presented by the Parties in these respects may be summarized as follows:

(a) Concerning point (i):

(a.1) By the Appellant:

(a.1.1) There was no support in the application as originally filed for the lower limit of 2 ppm of magnesium content set out in Claim 1 of the main request.

(a.1.2) The composition of Example 1 of the patent in suit contained specific PPE and HIPS resins in specific amounts.

(a.1.3) The fact that no discoloration was observed at the surface of the blow molded article when the amount of magnesium was as low as 2 ppm in the phosphate additive used in that composition was linked to the specific compatibility of this phosphate additive with the other components of the blends.

(a.1.4) Thus, the value 2 ppm could not be generalized.

(a.2) By the Respondent:

(a.2.1) There was no indication in the patent in suit which could have suggested that the lower limit of 2 ppm would be valid only for the specific composition disclosed in Example 1 in order to obtain blow molded articles with absence of discoloration at their surface.

(a.2.2) Reference was made to the decision T 0201/83 (OJ EPO 1984, 481) in that respect.

(b) Concerning point (ii)

(b.1) By the Appellant:

(b.1.1) There were several analytical methods (e.g. emission spectroscopy, absorption spectroscopy, mass spectroscopy, or gravimetric methods) which could be applied to determine the magnesium content in the phosphate additive. There were further several methods for preparing the samples to be tested.

(b.1.2) These different methods of determination would give very different results.

(b.1.3) There was however no indication in the patent in suit how the lower limit of 2 ppm of magnesium in the phosphate compound should be determined. Thus, Claim 1 would lack clarity.

(b.1.4) Furthermore, the skilled person would not know whether he was working inside or outside the scope of Claim 1. Thus, the main request did not meet the requirements of Article 83 EPC.

(b.1.5) Magnesium could be incorporated into the composition by other components than the specific phosphate such as talc, clay, mica, or flame retardants such as magnesium hydroxide (cf. patent in suit paragraph [0021]) as well by the PPE or the HIPS.

(b.1.6) Claim 1 did not however define the total amount of magnesium.

(b.2) By the Respondent:

(b.2.1) The skilled person would know the method in order to determine the lower limit of 2 ppm in the phosphate compound.

(b.2.2) The analytical method relied on in the last submission of the Appellant (cf. Annex 1) would allow to determine such a lower limit.

(b.2.3) It should also be noted that neither for the CIELAB tests submitted by the Appellant nor in document D9 (cited by the Appellant in order to establish that the phosphate Fyrolflex® RDP had a content of 5 ppm Mg before the priority date of the patent in suit) was a method for determining the magnesium content of the phosphate compound mentioned. This showed that there was no difficulty for the skilled person to determine low amounts of magnesium in the phosphate compound.

(b.2.4) Thus, the Appellant had not shown that the magnesium content of the phosphate could not be determined.

(b.2.5) Even if magnesium could be incorporated by other components into the composition, the total content of magnesium was not essential, since it was the content of magnesium in the phosphate over 50 ppm which caused the discoloration.

(c) The Board, after deliberation, informed the Parties that it considered that the main request met the requirements of Articles 123(2) EPC and 84 EPC and that it was inclined to interpret Claim 1 as not placing an upper limit on the content of magnesium in the composition.

(d) The Appellant having conceded that the subject-matter of Claim 1 was novel over D1, D3, D4 and D5, the discussion moved to the question of assessment of inventive step.

The essential arguments presented by the Parties in that respect may be summarized as follows:

(d.1) By the Appellant:

(d.1.1) The CIELAB measurements carried out on the molded plates (cf. tests submitted with the letter dated 12 June 2003) showed that the amount of magnesium in the phosphate had no influence on the surface appearance of the molded parts.

(d.1.2) Document D1 could be considered as the closest state of the art.

(d.1.3) Starting from D1 the technical problem should be seen in the provision of further flame retardant thermoplastic compositions comprising a PPE and a phosphorus additive and showing reduced plate out of the phosphorus additive at the surface of molded parts.

(d.1.4) The general formula of the phosphorus additives disclosed in D1 encompassed the specific phosphate component according to Claim 1. It was further known (cf. D4 (Examples 3 and 4) and D6) that such phosphorus additives might contain magnesium.

(d.1.5) Thus, the technical problem had been solved by arbitrarily selecting a previously undisclosed phosphorus additive containing a specific content of magnesium among the phosphorus additives already disclosed in general in D1.

(d.1.6) Consequently the subject-matter of Claim 1 of the main request did not involve an inventive step.

(d.2) By the Respondent:

(d.2.1) The tests submitted by the Appellant with its letter dated 12 June 2003 could not be compared with the tests carried out in the patent in suit, since the parts had not been blow molded.

(d.2.2) The CIELAB measurement test did not give any information on the surface discoloration.

(d.2.3) Furthermore there was no indication of the amount of phosphate in the tested compositions, so that it was not clear whether the amount of phosphate was within the claimed amounts according to Claim 1.

(d.2.4) Consequently, these tests were not relevant.

(d.2.5) In contrast the tests carried out in the patent in suit showed the effect of the magnesium content of the phosphate on the surface discoloration of the blow molded parts.

(d.2.6) The documents cited by the Appellant were silent on the amount of magnesium contained in the phosphate additive to be used in the PPE compositions.

(d.2.7) Consequently, there was no suggestion in the prior art that discoloration in blow molded articles made from PPE compositions comprising such phosphate additive might be associated with the magnesium content of the phosphate additive.

XVII. The Appellant requested that the decision under appeal be set aside and the patent be revoked.

The Respondent requested that the decision under appeal be set aside and the patent be maintained in amended form on the basis of the main request as submitted with the letter dated 25 May 2007, or, in the alternative, on the basis of one of the auxiliary requests 1 to 7 as submitted with the letter dated 25 May 2007.