T 999/10 – A Case For A Cascade

The present decision is interesting for all those who struggle with “extending limitations” such as found in several cases discussed on this blog (here, here, here and here).

Both the patent proprietor and the opponent had filed an appeal after the Opposition Division had maintained the opposed patent in amended form.

Claim 1 of the main request before the Board read, in English translation (the amendments with respect to claim 1 as granted are highlighted):

Hot-extrudable pressure-sensitive hot-melt adhesive having, at its end use temperature of generally between -20 and +40°C, an elastic modulus G' less than 5∙10⁵ Pa, comprising a blend of:

• from 15 to 55% by weight of at least one compatible tackifying resin and
• from 45 to 85% by weight of one or more styrene block copolymers obtained from styrene monomers and from at least one other comonomer, such as ethylene, propylene, isoprene, butadiene and butylene, said copolymers constituting linear, radial or star-shaped diblock, triblock or multiblock type structures in which the intermediate block consists of at least one of the above-mentioned comonomers, said copolymers having:
• a mass percentage of the styrene phase in the polymer of between 10 and 35%;
• a mass percentage of diblock structures in the polymer greater than 30%; and
• a melt flow index according to condition No. 10 of the NFT 51-016 standard of between 2 and 40 g/10 min;

such that this blend has:

• a viscosity, at a temperature of at least 130°C 150°C (measured according to the IS0 1 143 standard), lying within a range located above the power curve:

η = 22000∙(dγ/dt + 200)^-0.82

in which dγ/dt – the shear rate – is between 100 and 1000 s^-1;

• a tensile strength at a pull rate of 1 m∙s^-1 lying within the range located below the polynomial curve:

y = – 2.82∙10^-16∙x⁶ + 5.92∙10^-13∙x⁵ – 4.97∙10^-10∙x⁴
+ 2.15∙10^-7∙x³ – 4.99∙10^-5∙x² + 6.26∙10^-3∙x + 4.71∙10^-2

where y – the ordinate – represents the stress expressed in MPa and X – the abscissa – represents the deformation expressed in %;

and in which the mass percentage of the styrene phase in the polymer is comprised between 10 and 25%, the mass percentage of diblock structures in the polymer is greater than 40% and the styrene block copolymer is a copolymer of styrene/isoprene/styrene type

and in which the tackifying resin is a resin or a blend of resins conventionally used in hot-melt adhesives will be used, chosen among:

• rosin or its derivatives, especially rosin esters, optionally hydrogenated ones;
• polyterpenes, terpene phenolics or derivatives thereof; and
• optionally hydrogenated polymers coming from aliphatic or aromatic cuts or blends of these cuts; having a softening point measured according to the EN 1238 standard of between 5 and 150°C, and preferably between 80 and 140°C;

and in which the compatible tackifying resin comprises a predominant resin having pronounced aliphatic character ;

the tensile strength being measured using the following method:

• dumbbells are cut, using a blanking die of the H2 type, from 80*80*2 mm plaques of a hot-melt pressure-sensitive adhesive that were prepared beforehand at 160°C. with a pressure and venting cycle; 
• the tensile test is carried out by means of a hydraulic mechanical testing machine, the distance between the jaws, defined as the useful length L0, being 50 mm, the maximum displacement of the hydraulic ram L being 320 mm, the maximum deformation being of 640%, equal to 100*L/L0, and the rate of displacement of the piston being set at 1 m∙s^-1.

The most interesting part of the decision (in my opinion) deals with the question whether this amendment complied with A 123(3):

*** Translation of the French original ***

[3.1] During the opposition and opposition appeal proceedings, the patent proprietor has tried to limit the block copolymers of the composition to styrene copolymers having blocks of the styrene/isoprene/styrene type.

[3.2] [The opponent] has pointed out that the scope of protection conferred by the European patent had been extended as a consequence of the amendment of claim 1, because when open claims (“comprising”) directed at compositions are amended, the amendment the purpose of which was to limit a claim de facto extended the scope of protection conferred by the claim (see T 2017/07). [The opponent] chose the following example to illustrate its reasoning:

A composition containing 10 % by weight of tackifying resin, 30% by weight of styrene/isoprene/styrene (SIS) block copolymer and 60% by weight of [styrene/butadiene/styrene] block copolymer (SBS) would not fall within the scope of claim 1 as granted because the sum of SIS copolymers and SBS copolymers exceeds 85% by weight and the amount of tackifying resin is too small. However, the very same composition would fall within the scope of claim 1 as amended: indeed, the quantity of SBS was not to be taken into account in the claimed composition, which means that the recalculated amounts of essential components present in the composition was of 25%  by weight for the tackifying resin and 75% by weight of SIS. Nevertheless, the open formulation (“comprising”) of claim 1 did not exclude that SBS was present in the adhesive.

[3.3] The Board does not share this opinion of the opponent. The amendment concerning the block copolymers does not extend the scope of protection of claim 1.

The patent proprietor has maintained the broader definition of the block copolymers according to claim 1 as granted in the amended claim. It has added an additional restriction regarding the SIS-type block copolymer contained in dependent claim 3 (which corresponds to original claim 3), by using the expression “and in which … ” (et dans lequel …)

… from 45 to 85% by weight of one or more styrene block copolymers obtained from styrene monomers and from at least one other comonomer, such as ethylene, propylene, isoprene, butadiene and butylene, said copolymers constituting linear, radial or star-shaped diblock, triblock or multiblock type structures in which the intermediate block consists of at least one of the above-mentioned comonomers, …

and in which … the styrene block copolymer is a copolymer of styrene/isoprene/styrene type

[3.4] The drafting of the claim in cascade form, which is based on the wording used for characterising the block copolymers, does not leave any doubt on the intention of the patent proprietor to exclude all block copolymers other than the SIS-type copolymers from the intended scope of protection. A reader familiar with the way in which patent claims are drafted would deduce that from now on, among the block copolymers disclosed, only SIS-type copolymers could be present in the adhesive. As a consequence, the amendment does not violate A 123(3).

[3.5] Even if the interpretation proposed by the opponent, according to which the open wording (“comprising”) of the claim would not exclude the presence of other block copolymers, such as SBS, in the composition, was to be adopted, it does not alter the fact that drafting of the claim in cascade form chosen by the proprietor always requires the condition limiting the quantity of block copolymers defined more broadly in claim 1 as granted to be satisfied in the amended claim, too.

In other words, the condition limiting the quantity of block copolymers defined more broadly in the claim as granted is still present in the amended claim, even if both SIS and SBS are present. In such a case, the quantity of SBS in the composition indeed has to be taken into account when the quantity of block copolymers that may not exceed 85% by weight is calculated. This means that in the example mentioned by the opponent, the calculation of the total amount of block copolymers always has to take account of the quantity of SBS.

[3.6] To sum up, even if the amended claim was to be interpreted by insisting on the open wording (“comprising”) of the claim, the intended scope of protection of the amended claim is not broadened with respect to the claim as granted. What is decisive is that the condition that is expressed in the claim as granted has also been incorporated into the claim as amended.

[3.7] Consequently, the amendments reduce the scope of protection conferred by the patent as granted and, therefore, comply with the requirements of A 123(3).

Should you wish to download the whole decision (in French), just click here.

The file wrapper can be found here.