Saertex France SAS v Hexcel Reinforcements UK Ltd

A patent claim is not an impermissible free-beer claim merely because it uses a functional feature, provided the feature reliably enables the skilled person to perform the invention. A claim to a reinforcement intended for embedding in a matrix is construed by reference to suitability, rather than the operator’s subjective intention. A technical prejudice must be established by convincing evidence that it was widely held in the relevant field. The court construed “present only on the surface” purposively, requiring penetration insufficient to create a significant possibility of fibre adhesion and local loss of thickness. The granted and conditionally amended claims were invalid for lack of novelty or inventive step.

Saertex was the proprietor of European Patent (UK) No. 1 781 455 B1, concerning the treatment of fibre-based reinforcement material with repositionable adhesive. It alleged that Hexcel’s products infringed claims 1 and 2 as granted. Saertex conditionally applied to amend the patent by adding limitations concerning adhesive location and hot-melt glue.

Hexcel counterclaimed for invalidity on grounds of lack of novelty, lack of inventive step and, conditionally, insufficiency. The court considered the construction of the claims, the skilled person, and three items of prior art: Cytec, Crystic and Working with Fibreglass.

1. Construction and skilled person. The skilled person was a manufacturer of treated reinforcements. A wider team including composite manufacturers and component suppliers was unnecessary. The claimed armature meant fibre-based material suitable for embedding in a matrix and having a reinforcing effect; the operator’s subjective intention was irrelevant.

2. Infringement. A discontinuous array of adhesive dots could constitute a layer. The sequence in which adhesive contacted the removable insert and reinforcement was immaterial where the result was a layer between them. “Present only on the surface” meant that adhesive penetration must not cause fibres to adhere in a way creating a significant possibility of local reduction in thickness. Hexcel conceded that its products satisfied that construction. All claims in issue were therefore infringed if valid.

3. Free-beer objection. Claim 1 as granted was not invalid merely because it claimed the use of any repositionable adhesive. All variations of the claimed step were enabled. The law did not require every future variety of a claim element to have been discovered.

4. Validity. Claim 1 as granted lacked novelty over Cytec and Working with Fibreglass and lacked inventive step over Crystic. Claim 2 as granted lacked novelty over Working with Fibreglass and lacked inventive step over Cytec and Crystic. The conditionally amended claim 1 was not obvious over Cytec or Working with Fibreglass, but was obvious over Crystic. Amended claim 5 was obvious over Crystic.

5. An alleged technical prejudice requires a high standard of proof that the supposed prejudice was widely or universally held. The evidence did not establish such a prejudice. The Patent was invalid both as granted and as conditionally proposed to be amended.