Patent

Petition for revocation - Obviousness - Claimant company developing processes for development of pigment

Sudarshan Chemical Industries Ltd v Clariant Produkte (Deutschland) GmbH: ChD (Patents) (Mr John Baldwin QC (sitting as a deputy judge of the Chancery Division)): 13 June 2012

The claimant company was an Indian manufacturer and supplier of pigments, in particular, a yellow pigment (PY 191).

In about 2005, it developed a version of PY 191, Sudafast Yellow 132 (132), but had not sold it in the UK or the US because it had been protected by two patents (EP 0361431 (431) and US 5047517 (517)), the disclosures of which were identical in all material respects. Example 1 of 431 and 517 described a process for the manufacture of PY 191. The product of the example 1 process after filtration but before drying was wet cake.

In September 2009, 431 expired by effluxion of time. The claimant developed the process of example 1 (the old process) and started to sell products in accordance with that process. The defendant company was the proprietor of a product and process patent, EP 1170338 (338), in relation to a polymorphic form of PY 191 (the beta form). Claim 6 of 338 stated: ‘C.I. Pigment Yellow 191 of [a particular chemical composition] characterised by the following reflections in the X-ray powder diffractogram, measured with CuKa radiation: β-polymorph [the peaks of the β-polymorph are then set out]’.

Claim 7 of 338 stated: ‘A C.I. Pigment Yellow 191 mixture comprising at least 10%, preferably at least 25%, in particular at least 50%, with particular preference at least 75%, with very particular preference at least 90%, of the β-polymorph defined in claim 6’ (claims 6 and 7, the product claims). Claim 8 of 338 stated: ‘The use of C.I. Pigment Yellow 191 as claimed in claim 6 or 7 for pigmenting varnishes, polymers, printing inks, aqueous or solventborne pigment preparations, electrophotographic toners and developers, powder coating materials, inks, preferably inkjet inks, colour filters, and for colouring seed’ (the use claim).

In November 2009, the defendant sent a letter to the claimant drawing attention to 338, asserting that 132 contained mostly PY 191 in the form of the protected crystal modification and that any export of the claimant’s product or article containing it into a country where the defendant held a patent would cause patent infringement. The claimant stopped selling 132 to any customer for use outside India.

It revisited its implementation of example 1, leading to the development of another process (the new process). The claimant sought an order that 338 be revoked and an inquiry as to damages or an account of profits for unjustified threats of patent infringement proceedings. The defendant counterclaimed, alleging infringement by reason of the dealing or intended dealing in 132. It alternatively put forward conditional amendments.

It fell to be determined: (i) whether a skilled person would be experienced in pigment production; (ii) whether pigment production would be within the common general knowledge; (iii) whether the claimant had merely been working the prior art or obvious variations of it and, if so, whether that explained the levels of the beta form in the claimant’s product; (iv) whether the 338 product and use claims had been valid; (v) whether the amendments to 338 should be allowed; and (iv) whether unjustified threats of patent infringement proceedings had been made. Section 76 of the Patents Act 1977 was considered. The application would be allowed.

(1) The skilled addressee would have the characteristics of individuals with experience in pigment production and would typically be educated to undergraduate or doctoral levels in their specialist subject areas. Thus, chemists would have basic chemical knowledge of organic reactions and how to carry out operations such as syntheses, isolation, drying and characterisation (including by X-ray powder diffractometry) of azo pigments (see [6] of the judgment).

(2) It had been accepted that the following had been common general knowledge at the priority date: (i) optimisation of pigment production had been a common and necessary industry practice generally, and in particular if the source had been a patent document; (ii) a variety of techniques had been known to enhance crystal quality, these had included after-treatment (thermal treatment) and adding appropriate auxiliaries to the reaction medium, including adding rosin, which had been known to inhibit crystal growth resulting in transparent pigments with fine particle sizes; (iii) the use of co-couplers and co-amines for improving colouristic properties; (iv) the use and availability of a variety of different diazotisation and coupling processes as well as finishing and after-treatments; (v) the use of a wide range of temperatures for drying pigments; (vi) high-temperature drying had been detrimental to the properties of pigments produced; (vii) the use of flushing, by which pigments in an aqueous phase had been directly transferred to a non-aqueous phase; (viii) the use of wet cake as a feedstock in plastic, ink and coating/paint applications (agreed as a general statement but the defendant contended that it depended on the individual pigment); (ix) the organic compounds had tended to form different polymorphs; (x) that polymorphism might arise from the inclusion of water and solvent molecules in the lattice structure; and (xi) that polymorphic forms could display considerably different properties - important for the manufacture of pigments (see [16] of the judgment).

(3) The objections that had been raised by the defendant to the contention that the old and new processes had been no more than an ordinary and obvious implementation of example 1 had been entirely hypothetical and had not been based on any matters of substance (see [26], [28] of the judgment).

(4) The product claims of 338 would be bad for want of novelty and inventive step as the inevitable result of carrying out example 1 had been wet cake containing 100% of the beta form. Further, carrying out example 1 with the type of obvious variations that would be introduced in order to commercialise the product would also lead to wet cake with 100% of the beta form. The use claim would fail for lack of inventive step on the basis of persuasive expert evidence that it had been obvious to have used PY 191 wet cake in plastic, ink and coating and paint applications (see [41], [42], [43] of the judgment).Patent 338 would be revoked (see [73] of the judgment).

(5) In the instant case, the amendments had been anticipated by the inevitable result of carrying out example 1 and had further lacked inventive step by reason of the fact that the skilled addressee carrying out obvious optimisations of example 1 would produce wet cake comprising 100% of the beta form, and in the light of the finding that an obvious use of wet cake had been in pigmenting polymers and the anticipation had not been accidental. Further, an amendment had been contrary to section 76 of the act and not allowable as there had been no disclosure in the original specification either that it had been inventive or that there had been technical significance in the use of PY 191 (see [48], [49], [55], [62] of the judgment).

The amendments would not be allowed (see [64] of the judgment).

(6) Despite the absence of communication of any threats to the claimant’s customers, if the claimant had known that its customers would be harassed by patent infringement claims, it would be wary of supplying those customers for fear of damaging its business relationships with them. Further, the defendant had had reason to suspect that 338 had been invalid (see [69], [71] of the judgment).

The action in respect of the threat of patent infringement proceedings would succeed (see [73] of the ­judgment).

Martin Howe QC and Henry Ward (instructed by Charles Russell) for the claimant; Antony Watson QC and Tom Mitcheson (instructed by Taylor Wessing) for the defendant.