Saturday, 2 June 2012

T 1239/08 – Guidance Required

The present appeal of the opponent against the maintenance of the opposed patent in amended form contains interesting passages on novelty and the choice of the closest prior art.

[4.1] According to the [opponent], claim 1 of the main request lacked novelty over document D2, particularly over example 12 in combination with the general disclosure in column 3, line 58 to page 4, line 2 and more particularly the disclosure in column 3, lines 66-73.

[4.2] Claim 1 of the main request is directed to a dispersion of insoluble particles in a liquid vehicle with the features (a) to (d) […]. According to feature (d) the insoluble segment of the polymer dispersant has cross-linking moieties which are cross-linked to at least one cross-linkable component which is insoluble in the liquid vehicle and is selected from itself or a polyfunctional mono-, oligo- or polymer to form an encapsulation network.

[4.3] Example 12 of document D2 discloses the preparation of a predominantly aqueous pigment dispersion using as a polymer dispersant a copolymer with a relatively hydrophobic main chain (corresponding to the insoluble segment(s) in step (c) of the presently claimed subject-matter) derived from methyl methacrylate, a small amount of methacrylic acid and the acrylate part of the Carbowax 750, and pendent relatively hydrophilic side chains (corresponding to the soluble segment(s) in step (c) of the presently claimed subject matter) of the polyethylene blocks derived from Carbowax 750, which provide water-dispersibility. In a first step a copolymer solution in isopropanol and methyl ethyl ketone is prepared. Into this solution are ground titanium dioxide pigments. Then water is slowly added under vigorous stirring (i.e. the polarity is changed from “strong polar” to “intensely polar”, which is sufficient to precipitate the less polar polymeric component […] and a fine stable pigment dispersion is obtained, which does not flocculate upon addition of further quantities of water. The copolymer of example 12 is a graft polymer according to the IUPAC definition provided in document D11, which was not disputed by the [patent proprietor] during oral proceedings. Thus, example 12 discloses a particle dispersion with the features (a) to (c).

The feature that is clearly missing however, is the cross-linking in the precipitated (i.e. insoluble) component, as required for the insoluble segments in the feature (d) of claim 1 of the main request. This was acknowledged by the [opponent] […].

[4.4] The part of the description of document D2 relied on by the [opponent] describes as a further embodiment of the invention the possibility of cross-linking the precipitated component with itself. This requires the presence of cross-linkable groups within the precipitated component. In column 3, lines 66-73 of document D2, it is disclosed that for this purpose a suitable precipitated component of the block or graft polymer would be a random copolymer of methyl methacrylate, methacrylic acid and glycidyl methacrylate, which is subsequently cross-linked by heating the dispersion to approximately 150°C. An alternative component would be a random copolymer of acrylate and methylol acrylamide which can be cross-linked by the same heat treatment.

[4.5] The Board notes that it is indeed established jurisprudence of the Boards of Appeal regarding the examination of novelty that the teaching of a document is not limited to the detailed information given in the examples, but embraces the disclosure of that document as a whole (see e.g. T 666/89, T 565/90 or T 941/98). Nevertheless, it is a general and consistently applied principle of the Boards of Appeal that for deciding lack of novelty there must be a direct and unambiguous disclosure in the state of the art which inevitably leads the skilled person to subject-matter falling within the scope of the claims. Thus, for the examination of novelty, different passages in a document can only be combined if there is a clear disclosure leading the skilled person to combine them.

[4.6] In the present case there is no such disclosure. The Board notes that the precipitated component in the copolymer of example 12 of document D2 cannot be cross-linked within itself due to the absence of suitable cross-linkable groups, like glycidyl methacrylate or methylol acrylamide. Furthermore, the Board notes that the cross-linking procedure of heating the particle dispersion to 150°C as described in column 3, lines 66-73 and illustrated in example 7 of document D2 would not be directly applicable to the aqueous dispersion of example 12 in view of the temperature of 150°C in the cross-linking procedure. Without additional adaptation this cross-linking temperature is incompatible with the liquid vehicle disclosed in example 12 comprising water, isopropanol and methyl ethyl ketone with boiling points well below 150°C. The skilled person therefore had no reason to apply the specific embodiment of cross-linking the precipitated component disclosed in columns 3/4 of document D2 to the specific embodiment of example 12 in which neither the polymer nor the liquid vehicle are suitable for the described cross-linking process.

[4.7] In support for its argument that the combination of example 12 and the general teaching regarding cross-linking is permissible, the [opponent] cited the decision T 332/87. In this decision it is stated that “In general the technical teaching of examples may be combined with that disclosed elsewhere in the same document, e.g. in the description of a patent document, provided that the example concerned is indeed representative for the general technical teaching disclosed in the respective document” (T 332/87 [2.2]). The [opponent] argued that example 12 is in perfect accordance with the general teaching in document D2 and thus perfectly combinable with the disclosure of cross-linking. It further pointed out that the Opposition Division (OD) has used an analogous reasoning in point 5.2, and especially 5.2.3, of the decision under appeal with regard to lack of novelty of the then pending main request in view of document (1).

[4.8] In the Board’s view, the case underlying the decision T 332/87 cannot be compared with the present case. In decision T 332/87 all examples including those which as a result of a combination with the description were considered as anticipating the claimed subject-matter were considered to be equivalent and directly compatible with the teaching of the description. In the present case, with regard to the embodiment of cross-linking not all examples are equivalent. Example 12 as explained in point [4.6] above cannot be cross-linked according to the process disclosed in the description without requiring additional modifications. Whether or not such modifications would be obvious for the skilled reader, i.e. whether or not, as argued by the [opponent], the skilled person would be taught how to modify example 12 to render it cross-linkable, if desired, is not a question related to novelty, but an issue to be examined in the assessment of inventive step. Decision T 332/87 cannot, therefore, support the [opponent’s] case. Nor is the OD’s decision concerning lack of novelty of previously claimed subject-matter in view of a different prior document relevant in this context.

[4.9] In this context, the [opponent] also submitted that there were no technical reasons why the cross-linking temperature was inappropriate given the fact that the claimed scope covered liquid vehicles containing up to 50% of any organic solvent including those with high boiling points and that the duration for the cross-linking was only 15 minutes. In addition, the [opponent] referred to document D4 which suggested cross-linking of aqueous dispersions under increased pressure “at on the order of 100°C to 150°C in some cases”.

[4.10] The fact that high boiling solvents are included in the presently claimed scope is immaterial for the examination of whether or not example 12 of document D2, which uses low boiling solvents, in combination with the disclosure in columns 3/4 directed to cross-linking anticipates the claimed subject-matter.

With regard to the [opponent’s] reference to document D4 the Board notes that according to established case law, when examining novelty combining separate pieces of prior art is only permissible in exceptional cases, such as for example when there is a specific reference in one prior art document (primary document) to a second prior art document, construing the primary document (see T 153/85 [4.2]). Document D4 is, however, not mentioned in document D2.

[4.11] For the reasons set out above, the Board concludes that the subject-matter of claim 1 of the main request is novel within the meaning of A 54.

A second interesting passage deals with the appropriateness of document D2 as closest prior art:

[5.5.1] The [patent proprietor] pointed out that the provision of aqueous pigment dispersions for inkjet printing ink was clearly one of the most important aspects of the present invention as could be seen from paragraph [0006] of the patent in suit. This paragraph also referred to the very unique and demanding requirements of the pigment dispersion to be used in inkjet printing applications. Document D2 was published in 1968, well before the inkjet printing technology was even available. According to the [patent proprietor], such a document would therefore be an unrealistic starting point as it could not provide the skilled person with any guidance and information on pigment dispersions suitable for inkjet printing ink. In support of its arguments the [patent proprietor] cited the decisions T 479/00 and T 870/96.

[5.5.2] The Board notes that the patent in suit is concerned with stable aqueous particle dispersions (paragraphs [0001] and [0007] of the patent in suit). Inkjet printing inks are apparently an important area for the application of such dispersions. However, the claimed subject-matter is not limited to inkjet printing inks. On the contrary, claim 1 of the main request relates in general to a dispersion of particles in a liquid vehicle. Furthermore, in paragraph [0002] of the patent in suit other application areas are mentioned, such as coatings (paints and inks), magnetic and optical recording media (tapes and disks), cosmetics (lipstick or nail polish), agriculture (insecticides) or pharmaceutical preparations. Moreover, example 8 of the patent in suit is concerned with the preparation of a tint suitable in the manufacture of paints. Coating compositions such as paints and lacquers are also mentioned in document D2 as an area in which the dispersion of particles disclosed in this document can be applied […]. This was also conceded by the [patent proprietor] in the oral proceedings before the Board. Being directed to the same purpose, namely providing stable particle dispersions useful in coating compositions like paints and sharing the maximum number of identical technical features, document D2, in the Board’s view, does not represent an unrealistic starting point for the assessment of inventive step.

The decisions T 479/00 and T 870/96 cannot support the [patent proprietor’s] case. 

In decision T 479/00 the Board considered a 65 year-old document which had not received any attention and which, as admitted by both parties, referred to a teaching which had never been put into practice on a commercial scale, as an unrealistic starting point. In the present case, as explained above, the [patent proprietor’s] argument concerning the age of document D2 are not convincing and document D2 being directed to the same purpose is not considered to be an unrealistic starting point.

In T 870/96 the Board pointed out that a generically different document cannot normally be considered as a realistic starting point for the assessment of inventive step. In the present case, document D2 referring to stable particle dispersions intended for the same use, namely coating compositions, like paints, cannot be considered as a generically different document.

[5.5.3] The [patent proprietor] also argued that the skilled person would not even remotely have considered cross-linking in an aqueous system in view of the teaching in document D2 referring to a cross-linking temperature of 150°C. In addition, according to the [patent proprietor], the unexpected effect that cross-linked graft-polymers are superior to cross-linked block or random copolymers was not derivable from document D2.

[5.5.4] These arguments, however, are related to the question of whether or not the present invention shows unexpected properties over the prior art which might support an inventive step or whether or not the claimed subject-matter would be obvious for the skilled person in the light of the prior art. They cannot be used to discard document D2, which has the same purpose and shares the maximum number of technical features with the claimed subject-matter, as a suitable starting point for the assessment of inventive step.

[5.6] For the above reasons the Board, in accordance with the [opponent], considers document D2 as the closest prior art and hence takes it as the starting point for the assessment of inventive step.

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