T 1626/13 17-05-2018

I. The appeal by the patent proprietor is against the interlocutory decision of the opposition division on the version in which European patent EP-B-0 892 705 met the requirements of the European Patent Convention.

II. During the opposition proceedings, the opponent had raised the grounds for opposition according to Article 100(a) (lack of novelty, lack of inventive step, lack of susceptibility of industrial application), 100(b) and 100(c) EPC 1973.

III. Oral proceedings were scheduled for 17 May 2018. However, since both parties announced that they would not attend, the board cancelled the oral proceedings and decided the present case in written proceedings.

IV. The appellant (patent proprietor) requests that the decision under appeal be set aside and that the patent be maintained on the basis of any of the claims filed as main request and as first to eighth auxiliary requests together with the statement setting out its grounds of appeal dated 18 September 2013. Moreover, the appellant requests that the case be remitted to the department of first instance for a decision on novelty and inventive step in respect of the subject-matter of claims 7 and 8.

It is observed that in its letter dated 30 December 2014 the appellant confirmed only the main request and the first to third auxiliary requests filed on 18 September 2013. However, silence on the part of the appellant on the remaining fourth to eighth auxiliary requests filed on 18 September 2013 cannot be interpreted as a withdrawal of those requests, as the withdrawal of a request generally requires the party's unambiguous statement of withdrawal. Consequently, the appellant's requests as presented in the statement setting out its grounds of appeal are still considered valid.

V. The respondent (opponent) requests that the appeal be dismissed. Moreover, the respondent requests that the case be remitted to the department of first instance for a decision on novelty and inventive step in respect of the subject-matter of claims 7 and 8.

VI. The documents referred to during the appeal proceedings include the following:

D8: ASTM D2663;

D10: GB-B-705 344;

D10-1: US-B-2,769,795 including file history.

VII. Independent claim 1 of the main request is worded as follows:

"A method of producing elastomer composite, from elastomer latex, particulate filler and optionally other ingredients, characterized by:

feeding a continuous flow of first fluid comprising elastomer latex to a mixing zone of a coagulum reactor defining an elongate coagulum zone extending from the mixing zone to a discharge end;

feeding a continuous flow of second fluid comprising particulate filler under pressure to the mixing zone of the coagulum reactor to form a mixture with the elastomer latex, the mixture passing as a continuous flow to the discharge end and the particulate filler being effective to coagulate the elastomer latex, wherein mixing of the first fluid and the second fluid within the mixing zone is sufficiently energetic to substantially completely coagulate the elastomer latex with the particulate filler prior to the discharge end; and discharging a substantially continuous flow of elastomer composite from the discharge end of the coagulum reactor."

In addition, the main request comprises an independent apparatus claim 6 and independent product claims 7 and 8.

VIII. Compared with the main request, claim 1 of the first auxiliary request contains the following amendments:

"... feeding a continuous flow of first fluid comprising elastomer latex under a line pressure of less than 69.0 kPa (gauge) (10 psig) to a mixing zone of a coagulum reactor defining an elongate coagulum zone extending from the mixing zone to a discharge end;

feeding a continuous flow of second fluid comprising particulate filler [deleted: under pressure] at a pressure above 2668 kPa (gauge) (300 psig) to the mixing zone of the coagulum reactor to form a mixture with the elastomer latex ..."

IX. The independent claims of the second auxiliary request read as follows:

"1. A method of producing elastomer composite, from natural rubber latex, particulate filler and optionally other ingredients, characterized by:

feeding a continuous flow of first fluid comprising natural rubber latex to a mixing zone of a coagulum reactor defining an elongate coagulum zone extending from the mixing zone to a discharge end;

feeding a continuous flow of second fluid comprising particulate filler under pressure to the mixing zone of the coagulum reactor to form a mixture with the natural rubber latex, the mixture passing as a continuous flow to the discharge end and the particulate filler being effective to coagulate the natural rubber latex, wherein mixing of the first fluid and the second fluid within the mixing zone is sufficiently energetic to coagulate at least 95% of the rubber hydrocarbon of the latex coagulate [sic] with the particulate filler prior to the discharge end; and discharging a substantially continuous flow of elastomer composite from the discharge end of the coagulum reactor."

"6. Apparatus for producing elastomer composite of particulate dispersed in elastomer, comprising:

a coagulum reactor defining a mixing zone and an elongate coagulum zone extending from the mixing zone to a discharge end wherein the coagulum zone has progressively increasing cross-sectional area between the mixing zone and the discharge end;

latex feed means for feeding elastomer latex fluid continuously to the mixing Zone [sic]; and

filler feed means for feeding particulate filler fluid as a continuous jet into the mixing zone to form a mixture with the elastomer latex fluid travelling from the mixing zone to the discharge end of the coagulum zone."

"7. An elastomer composite comprising particulate filler dispersed in elastomer, characterized in that the elastomer comprises natural rubber and the macro-dispersion D(%) of the particulate filler in the elastomer composite being less than 0.2% undispersed area, wherein measuring macro-dispersion involves measuring defects on a surface generated by microtoming, extrusion or cutting."

"8. An elastomer composite comprising particulate filler dispersed in elastomer, characterized in that the particulate filler is silicon coated carbon black, silicon treated carbon black, fumed silica, precipitated silica or a mixture of any of them and the macro-dispersion D(%) of the particulate filler in the elastomer composite being less than 0.2% undispersed area, wherein measuring macro-dispersion involves measuring defects on a surface generated by microtoming, extrusion or cutting."

X. The appellant's submissions may be summarised as follows:

Main request, claim 1 - inventive step

The subject-matter of claim 1 differed from document D10 not only in the features of

(a) an elongate coagulum zone extending from the mixing zone to a discharge end,

(b) feeding a continuous flow of second fluid comprising particulate filler under pressure to the mixing zone,

(c) to substantially completely coagulate the elastomer latex with the particulate filler prior to the discharge end

as established by the opposition division, but also in the aspect of

(d) the particulate filler being effective to coagulate the elastomer latex.

The object of the patent could be seen in providing a process which easily produced an elastomer latex having improved macro-dispersion, as disclosed in paragraph [0010]. It was a secondary object to provide a process for coagulating a latex/particulate filler mixture without the need to employ an acid or salt coagulation agent, as disclosed in paragraph [0012] of the patent.

The proposed solution was not rendered obvious by document D10, which stated that in the preparation of rubber compounds obtained from natural or synthetic rubber and carbon black an acid or other coagulating agent was required, even if its amount was substantially reduced (cf. page 2, lines 101 to 105). Moreover, in both embodiments of document D10 (cf. page 2, lines 47 to 57 and 58 to 70) the aqueous carbon black slurry and the latex were first mixed and subsequently coagulated by adding a coagulating agent. There was no indication in document D10 that the carbon black itself was effective to coagulate the elastomer latex, let alone that the elastomer latex was substantially completely coagulated with the particulate filler. This analysis of the order of processing steps disclosed in document D10 was further supported by document D10-1, a family member of document D10, and the file history of document D10-1. Since in document D10 either the latex was used as the energising fluid (first embodiment) or the carbon black slurry and the latex were both mixed while being under high velocity (second embodiment), there was no indication in this document to introduce the particulate slurry under pressure into the system, let alone that in this case the particulate filler itself could act as the coagulating agent, as in the present patent. This meant that the particulate filler slurry itself was effective to substantially completely coagulate the latex within the elongate coagulum zone of the reactor. These features were not obvious from document D10. Finally, document D10 did not disclose any details about the equipment for conducting coagulation. Only a latex mixing equipment was described. Consequently, there could not be any indication in document D10 regarding a process of simultaneously carrying out mixing and coagulation within an elongated coagulum zone extending from the mixing zone to a discharge end and discharging substantially coagulated material as required in claim 1 of the main request. The subject-matter of claim 1 was thus based on an inventive step.

First auxiliary request, claim 1 - added subject-matter

The additional features of the first fluid being fed to the mixing zone at a line pressure of less than 69.0 kPa (gauge) (10 psig) and of the second fluid being fed to the mixing zone at a pressure above 2668 kPa (gauge) (300 psig) had their respective basis on page 16, lines 11 to 13, and page 29, lines 12 and 13, of the application as filed. The requirements of Article 123(2) EPC were met.

Second auxiliary request - sufficiency of disclosure in respect of claims 7 and 8

In each of claims 7 and 8, macro-dispersion D(%) of the particulate filler in the elastomer composite was defined as being less than 0.2% undispersed area. The macro-dispersion data in the examples of the present patent was also disclosed as D(%), i.e. as percent undispersed area, which was in conformity with those claims. Furthermore, according to paragraph [0020] of the patent specification, macro-dispersion of the carbon black was measured as percent undispersed area for defects larger than 10 microns. These criteria were the basis for the method disclosed in paragraph [0007] of the patent specification. Therefore, there was a clear link between the reference to the macro-dispersion D(%) in claims 7 and 8 and the method in paragraph [0007] of the patent. It was also clear that the tests according to ASTM D2663 recited in paragraph [0060] were not applicable with regard to claims 7 and 8: as correctly stated by the opposition division, it was immediately evident to the skilled person that the Cabot Dispersion Chart method recited in paragraph [0060] and corresponding to test method A of ASTM D2663 could not be the test procedure used to determine the numerical values of the particulate filler dispersion in the numerous tables of the patent and in claims 7 and 8 because it was a qualitative test in which the dispersion was visually evaluated by comparing a sample with a reference of five standards (cf. document D8, page 404). Method B of ASTM D2663 was a method for determining the percentage of dispersion (i.e. not the undispersed area), as could be inferred from item 12 of document D8. Moreover, agglomerates of 5 mym or larger were counted, whereas in the patent specification the size of the agglomerates was 10 mym or larger. The same applied to method C of ASTM D2663. In view of that, the person skilled in the art, when considering test methods B and C of ASTM D2663, immediately saw that several modifications to these methods had to be conducted in order to determine the undispersed area as defined in claims 7 and 8 of the main request, modifications which were not mentioned in the present patent at all. However, when considering the method disclosed in paragraph [0007] of the present patent, he would immediately arrive at this parameter without further modifications. Therefore, it was without any doubt evident to the skilled person that the method of paragraph [0007] was the method used to determine the macro-dispersion according to claims 7 and 8. Since the patent itself disclosed in paragraph [0007] a method which gave guidance on how to directly obtain the undispersed area as required in claims 7 and 8, the opposed patent disclosed the subject-matter of claims 7 and 8 in a way sufficiently clear and complete to allow a person skilled in the art to carry it out without undue burden. This conclusion was in line with decision T 452/04.

Remittal to the department of first instance

The opposition division had not decided on novelty and inventive step for product claims 7 and 8. It was therefore requested that the case be remitted to the department of first instance for a decision on novelty and inventive step in respect of the subject-matter of claims 7 and 8.

XI. The respondent's submissions were essentially as follows:

Main request, claim 1 - inventive step

The disclosure of document D10 had to be established objectively. It was therefore inadmissible to use document D10-1 to interpret the teaching of document D10. On the substance, it was noted that the opposition division's conclusion that differing features (a) to (c) were obvious was left essentially uncontested by the appellant, and that the technical problems proposed by the appellant did not substantially differ from the problem suggested by the opposition division.

Regarding the argument that the particulate filler itself would act as the coagulating agent, it had to be taken into account that the wording of claim l required only that the mixing was sufficiently energetic to substantially completely coagulate the elastomer latex with the particulate filler; so this feature was not even novel over document D10 and consequently could not support an inventive step. Furthermore, the highly energetic mixing in document D10 was essentially the same as according to the claimed invention and belonged to the normal capability of the skilled person. In particular, in claim 1 of document D10 the wording was clear and non-limiting: " [...] suddenly combining the stream of the resultant carbon black-slurry with a stream of rubber latex, effecting substantially instantaneously uniform mixing of the two streams [...]"; claim 6 had a similar wording: " [...] and uniformly mixing the turbulent stream of the suspension with a stream of the rubber latex [...]". No difference in the energy content (high pressure) of the two streams was claimed or necessary. On the other hand, a different energy content of the two streams was not excluded by the claims either. The true condition to be fulfilled was the intensive mixing of the two streams in order to coagulate all of the carbon black - this was what document D10 taught and what the patent in suit required.

As to the sequence of mixing and coagulation, document D10 (cf. claims 1 and 6) disclosed a process in which the carbon black slurry was agitated and mixed with a stream of latex until coagulation had been effected, corresponding to the content of claim l of the patent in suit, "wherein mixing of the first fluid [elastomer latex] and the second fluid [the particulate filler under pressure] within the mixing zone is sufficiently energetic to substantially completely coagulate the elastomer latex with the particulate filler". In view of the above, the subject-matter of claim 1 was obvious in view of the teaching of document D10.

First auxiliary request, claim 1 - added subject-matter

The added features of the first fluid being fed to the mixing zone at a line pressure of less than 69.0 kPa (gauge) (10 psig) and of the second fluid being fed to the mixing zone at a pressure above 2668 kPa (gauge) (300 psig) were taken out of their respective contexts in the application as filed. In particular, their combination was not originally disclosed.

Second auxiliary request - sufficiency of disclosure in respect of claims 7 and 8

The relevant question was whether or not the skilled person was able to produce an elastomer composite comprising a particulate filler dispersed in the elastomer with a macro-dispersion of the particulate filler in the elastomer composite as required by claims 7 and 8, i.e. of less than 0.2% undispersed area, and more precisely whether the disclosure of the patent in suit was complete enough to give the skilled person sufficient and clear guidance on how to measure the macro-dispersion of less than 0.2% undispersed area. Even if the skilled person found in paragraph [0020] of the description that the formula given in paragraph [0007] of the description was the one to be used because those two passages were linked by the statement that the macro-dispersion of the carbon black was measured as percent undispersed area for defects larger than 10 mym, the measuring method in paragraph [0007] was disclosed in the "Background" section, meaning that this measuring method was to be used in the prior art and not specifically for the invention. Therefore, no direct relation to the measuring method which should be used for measuring the less than 0.2% undispersed area of claims 7 and 8 could be taken therefrom. Moreover, in paragraph [0005] of the description, also relating to the prior art, it was stated that considerable effort had been devoted to the development of procedures for assessing dispersion quality of carbon black in rubber, whereby the Cabot Dispersion Chart and various image analysis procedures were mentioned as examples. As these various image analysis procedures, for example those disclosed in ASTM D2663 (document D8), were known to the skilled person, he could also take these procedures into consideration when reading paragraph [0020] in relation to the invention. This was confirmed by paragraph [0060], which stated:

"[0060] The following test procedures were used in the examples and comparisons presented below".

and

"5. Dispersion: The Cabot Dispersion Chart method is used with subjective evaluation 0/50 x optical micrographs. (ASTM D2663 method)."

ASTM D2663 offered three different test methods for determining the degree of dispersion of carbon black in rubber, namely test methods A, B and C. Test method B measured the dispersion of carbon black in rubber quantitatively with the aid of a light microscope (cf. document D8, pages 406 to 410). Test method C was a further quantitative test method for calculating the dispersion of carbon black in the examined rubber specimen (cf. document D8, pages 410 to 413). Even if the person skilled in the art did not choose method A, it was clear that he would select either one of the two quantitative test methods B or C to determine the dispersion of carbon black in the rubber. The problem, however, was that in ASTM D2663 the cross-sectional area of all agglomerates of 5 mym or larger was counted and used to calculate the percentage of carbon black having a size of less than 5 mym (cf. Document D8, page 406, section 13.1). By contrast, in paragraphs [0007] and [0020] of the patent the cut-off size was defined as being 10 mym. Hence, the skilled person did not have clear and sufficient guidance, either on the basis of this disclosure in the patent in suit or on the basis of the common general knowledge, as to which of the available methods to choose for measuring the macro-dispersion of less than 0.2% undispersed area. Since the dispersed and the undispersed area complemented each other, substantially no modification was necessary when applying test methods B and C of document D8 in the context of present claims 7 and 8. Hence, three different measuring methods could in principle be used. Since it was unclear which was the correct one, the scope of protection of the patent was unclear as well, which violated the principle of legal certainty. The facts underlying decision T 452/04 cited by the appellant differed from the present case, so that this decision could not give any guidance. However, decisions T 225/93 and T 360/08 confirmed the respondent's view that the disclosure of the patent was insufficient.