Union Carbide Corporation v BP Chemicals Ltd

Factual and Procedural Background

Plaintiff sued Defendant for infringement of two European Patents (UK), Nos. 89,691 and 241,947, relating to the production of polymers in a fluidised bed reactor. Defendant allegedly infringed by producing linear low-density polyethylene ("LLDPE") at their manufacturing plant using two methods, referred to as Marks 1 and 2. Initially, Mark 1 was used, then replaced by Mark 2. Upon changing to Mark 2, Defendant sought a declaration of non-infringement, but this claim was superseded by Plaintiff's infringement claim. Defendant also sought a declaration of non-infringement for a variant called Mark 3 and counterclaimed for revocation of both patents. The patents concern the "condensing mode" operation of a fluidised bed reactor for polymer production.

The patents share the same priority date and specification but differ in claims. Patent 691 was applied for in 1983 and granted in 1989 after over six years' prosecution. Patent 947 was divided from 691 around 1987 and granted in 1992 after about nine years, with the court noting the delay caused by division was unsatisfactory and caused uncertainty for industry.

The Plaintiff called several witnesses, including senior executives and technical experts specializing in fluid dynamics and polymer production, none of whom were part of the original research team. Defendant called expert witnesses with extensive backgrounds in fluidised beds and polymer production, including a distinguished academic and industry practitioners involved in the development of Defendant's processes.

The case involves complex technical background on polymer types, fluidised bed reactors, heat removal challenges, and prior art processes, including Plaintiff's "Unipol" process and Defendant's Marks 1, 2, and 3 processes.

Legal Issues Presented

1. Whether Defendant infringed claims of patents 691 and 947 by the use of Marks 1, 2, and 3 processes.
2. The proper construction of the patent claims, particularly the scope of "re-introduction of said two-phase mixture" and the location and manner of liquid and gas introduction into the reactor.
3. The validity of the patents, including challenges based on anticipation and obviousness over prior art such as Fraser, Resine, Solvay, and Mitsui patents.
4. Whether the patents disclose the invention sufficiently for a skilled person to perform it (insufficiency).

Arguments of the Parties

Plaintiff's Arguments

• The patents cover a continuous process of polymer production by cooling the recycle gas stream below its dew point to form a two-phase gas-liquid mixture which is reintroduced into the reactor as fluidising gas.
• The key inventive concept is the use of the latent heat of vaporisation of the liquid to improve heat removal and production rate.
• The claim language allows for the liquid phase to be separated and re-entrained before introduction, so Defendant's Marks 2 and 3 processes infringe as they reintroduce both gas and liquid phases.
• Commercial success and long-felt want support the inventiveness of the patents.
• The patents are valid and sufficiently disclose the invention, including necessary design features such as baffles to prevent liquid pooling.

Defendant's Arguments

• The claims must be narrowly construed to require reintroduction of the two-phase mixture formed directly by cooling below dew point, not separate introduction of gas and liquid phases.
• The Marks 2 and 3 processes do not infringe because they separate the liquid and gas and introduce them separately, contrary to the claims.
• The point of liquid introduction in Marks 2 and 3 is above the isothermal region of the fluidised bed, outside the scope of claim 1 of patent 947.
• The patents are invalid for anticipation and obviousness based on prior art including Fraser, Mitsui, Solvay, and Resine patents.
• There was a common general knowledge prejudice against introducing liquid into fluidised bed polymer reactors, and the prior art discouraged condensation in the reactor system.
• The patents do not sufficiently disclose the invention, requiring significant engineering design work, particularly for baffle design.

Table of Precedents Cited

Precedent	Rule or Principle Cited For	Application by the Court
General Tire & Rubber Co Ltd v Firestone Tyre & Rubber Co Ltd [1972] RPC 457	Definition of novelty and anticipation requiring clear and unambiguous disclosure.	The court applied the principle that a prior publication must provide clear and unmistakable instructions to destroy novelty, rejecting Fraser as anticipation.
Scanditronix v Ion Chamber [1990] OJ 188	Equivalent to General Tire on novelty and anticipation.	Supported the court's approach to novelty and anticipation.
Hills v Evans (1862) 31 LJ Ch 457	Information in prior art must be equal to that in the patent to destroy novelty.	The court cited this to emphasize that a warning against an approach is not the same as disclosure of the approach.
British Ore Concentration Syndicate v Mineral Separation Ltd (1909) 26 RPC 124	Definition of common general knowledge in patent law.	Used to define the mental attitude of the skilled person.
Windsurfing International Inc v Tabur Marine (Great Britain) Ltd [1985] RPC 59	Framework for assessing obviousness in patent law.	The court applied the four-step Windsurfing approach to determine obviousness of the patents.
Unilever Ltd v Chefaro Ltd [1994] RPC 567	Clarification of identifying the inventive concept in obviousness analysis.	The court followed the approach to identify the essence of the claim's inventive concept.

Court's Reasoning and Analysis

The court began by construing the patent claims, focusing on the meaning of "re-introduction of said two-phase mixture" and the location and manner of liquid and gas introduction into the fluidised bed reactor. It held that the claims require reintroduction of the two-phase mixture formed directly by cooling the recycle gas below its dew point, with the liquid remaining entrained in the gas phase. Separate introduction of gas and liquid phases, as in Defendant's Marks 2 and 3 processes, falls outside the claims' scope.

The court found that Defendant's Mark 1 process infringed the claims, but Marks 2 and 3 did not. It further held that the point of liquid introduction in Marks 2 and 3 is above the isothermal region of the bed, contrary to claim 1 of patent 947 which requires introduction below the region of maximum desired temperature.

On validity, the court rejected anticipation attacks based on Fraser, Resine, and Solvay patents. Fraser was not novelty-destroying because it discouraged condensation in the reactor system and did not disclose continuous operation in condensed mode as claimed. Resine did not disclose entrained liquid in the gas phase, and Solvay disclosed only a batch process with no uniform mixture of gas and liquid introduced below the isothermal region.

The court applied the Windsurfing framework for obviousness, identifying the inventive concept as the continuous operation of a fluidised bed polymerisation process using a cooled recycle gas stream below dew point forming an entrained two-phase mixture reintroduced into the reactor to improve heat removal. It concluded that prior art did not render the invention obvious, rejecting hindsight-based arguments.

Regarding common general knowledge, the court acknowledged that while introduction of liquid into fluidised beds was known in other contexts, there was a prevailing prejudice against such practice in polymerisation fluidised beds due to operational difficulties feared by skilled persons. This prejudice was supported by contemporaneous documents and witness evidence.

The court accepted Plaintiff's evidence of commercial success and long-felt want as supportive of inventiveness, particularly for claim 1 of patent 691.

On insufficiency, the court found that although some engineering design (such as baffle design) was needed for optimal operation, the patents sufficiently disclosed the invention for a skilled person to perform it. The design work did not render the patents insufficient or detract from commercial success.

Holding and Implications

The court held that Defendant's Mark 1 process infringed claim 1 of patent 691 and claims 1 and 3 of patent 947. However, the Marks 2 and 3 processes did not infringe due to the court's construction of the claims and factual findings regarding process operation.

Both patents were held valid on the grounds of novelty, non-obviousness, and sufficiency of disclosure.

The decision confirms that patent claims must be construed strictly according to their language and the inventor's purpose, particularly regarding technical details such as the physical state and manner of introduction of reactants in chemical processes.

No new precedent was set beyond the application of established principles of claim construction, novelty, obviousness, and sufficiency in the context of chemical patent law.