EPO - T 2451/09 - Sealing slide fastener with teeth welded onto the tapes which they join

Decision date


Decision No.

T 2451/09 - 3.2.04





The opponent, YKK CORPORATION, was represented by Axel Casalonga, European Patent Attorney.

The decision of the Board of Appeal completely follows the position of YKK and revokes the patent of RIRI for lack of sufficient disclosure which is a rather seldomly accepted ground.

The opposition had been filed against European patent No. 1 294 248 to RIRI for insufficient disclosure of the invention, among other grounds.

The invention concerns a sealing slide fastener with opposing elastic tapes that are pressed together edgewise by teeth on the tapes that are made to mesh by a slider - basically an impervious zipper. The teeth are formed of two halves on opposite sides of the tapes. The invention’s main thrust is towards preventing infiltration of water through holes in the tape that allow the halves to be joined. To this end the patent essentially proposes using materials for teeth and tape that can be "welded together chemically", in such a way that when the teeth are injection moulded in position on the tapes, they are welded “by chemical bonding”.

The patent proprietor, Company RIRI, argued that the expression "welded together chemically" is not standard usage. It does not refer to any particular recognized type of welding. The skilled person - a plastics engineer involved in the manufacture of a plastics fastener with extensive textbook knowledge of plastics – must therefore try to understand the expression from context.

The Boards notes that the particular type of chemical bond - whether covalent, ionic or hydrogen, primary or secondary, strong or weak - is not specified in the patent. Nor will it be apparent to the skilled person from his common knowledge whether a particular bond type is meant and which one, as all are known to play roles in polymer chemistry. All he has is the information that the bond must result in teeth and tapes welding.

According to the Board, in the light of the common general knowledge in the field, it becomes clear that the skilled person faces a daunting task. For one, it shows that thermoplastic elastomers (TPEs) form a large class of elastomeric materials, which vary widely in their ability to weld with selected resins. More importantly, it emerges from the common general knowledge, that it is not yet fully understood how elastomers adhere, whether the mechanism involved is purely physical or chemical in nature, let alone which materials produce a chemical bond and by what means.

The skilled person would at the priority date not have known with any certainty from his common general knowledge how elastomers, and in particular TPEs, adhere. He would have been unable to say whether they adhere by physical entanglement or by any of a number of chemical bonding mechanisms, or, indeed whether some materials adhere physically, while others adhere chemically, much less which ones and under which conditions.

In the Board’s view the effort involved goes far beyond that, say, of routine trial and error. It amounts to an extensive research programme that puts undue burden on the skilled person in his attempts to put the invention into practice, and which may not even lead to success.

The Board therefore decides to revoke the patent.