May 18, 2022
The Patent Trial and Appeals Board (PTAB) recently overruled an examiner’s finding of obviousness of claims premised on a “missing” moisture permeability feature in a composition designed for moisture absorption.
US Appl. Serial No. 14/240,617 related to adhesive siloxane compositions and its main claim, on appeal, recited (emphasis added)
[a]n adhesive composition comprising:
a polysiloxane adhesive,
wherein the polysiloxane adhesive constitutes at least about 40% by weight of the adhesive composition; and
one or more hydrocolloids dispersed in the polysiloxane adhesive,
wherein the one or more hydrocolloids constitute from about 5% to about 60% by weight of the adhesive composition;
wherein the polysiloxane adhesive is a one-part adhesive and at least partially crosslinked;
wherein the polysiloxane adhesive is selected from the group consisting of
(i) an adhesive having a solids content of about 60%, a viscosity of about 2600 mPA·s, and which exhibits a rheology at 0.01 rad/sec at 30°C of about 5x106 P,
(ii) an adhesive having a solids content of about 60%, a viscosity of about 1200 mPA·s, and which exhibits a rheology at 0.01 rad/sec at 30°C of about 5x106 P, and
(iii) a combination of (i) and (ii); and
wherein the adhesive composition has a moisture vapor transmission rate (MVTR) of greater than 800 g/m2/24 hours.
The claims were rejected as obvious over the combination US 2004/0241215 A1 (Lipman, the applicant’s own work), US 2011/0144599 A1 (Croizat), and US 2002/0169405 A1 (Roberts). The PTAB indicated that Croizat and Roberts were not relevant to the feature in question.
The rejection relied upon the moisture transmission rate in an occlusive layer in Lipman, i.e., a layer different from the adhesive layer claimed. The examiner relied upon Lipman’s bolded occlusive layer moisture transmission rate described in ¶ :
[t]he occlusive top layer, in one embodiment, has a moisture vapor transmission rate (MVTR) of substantially zero. In another embodiment, the occlusive top layer has a moisture vapor transmission rate (MVTR) in the range of about 100 to 2000 g/m2/24 hours. In one embodiment, the MVTR ranges from about 400 to about 1000 g/m2/24 hours, and in one embodiment from about 600 to about 800 g/m2/24 hours. In one embodiment, where larger dressings are needed and treatment requires that a portion of the wound fluid be evaporated through the dressing, the MVTR may be as high as 4000 g/m2/24 hours or greater[,]
rather than Lipman’s description in the second paragraph (¶ ) of the Summary section of a moisture absorbing capacity of 3000 g/m2/24 hours. The examiner argued that both the occlusive layer and the adhesive layer could be reasonably interpreted as adhesive, and that “it would have been well within the ordinarily level of skill in the art at the time of the invention to formulate a pressure sensitive adhesive layer with the claimed MVTR to maintain the breathability of an adhesive dressing.” The examiner argued that a skilled artisan would have appreciated from Lipman that wound fluid should be allowed to evaporate at a sufficient rate through the entirety of an adhesive composition (i.e., all layers) for effective wound treatment, and thus concluded that
it would have been obvious at the time of the invention that any other layers in an adhesive dressing, such as a layer comprising a polysiloxane adhesive, should have an equal or higher MVTR than that of an occlusive top layer to maintain the breathability of the entire adhesive dressing.
The applicant argued that, generally, the adhesive layer’s function is to absorb water and the occlusive layer’s function is to release some moisture vapor from the layer underneath, and that there was nothing in Lipman teaching a need for the adhesive layer to breathe, as was implied by the claim feature that “the MVTR may be as high as 4000 g/m2/24 hours or greater.”
Citing In re Fritch, the PTAB cautioned that “[i]t is impermissible to use the claimed invention as an instruction manual or ‘template’ to piece together the teachings of the prior art so that the claimed invention is rendered obvious.” In re Fritch, 972 F.2d 1260, 1266 (Fed. Cir. 1992). The PTAB indicated that there was no evidence that adhesive layers should have an at least equal MVTR to the occlusive top layer, instead noting that Lipman taught making the occlusive layers moisture absorbent. The PTAB took the position that Lipman was focused on moisture absorption by the adhesive layer, and was silent on the flow of moisture through the adhesive layer. Accordingly, the PTAB overturned the examiner’s conclusion of the obviousness of the claims including the MVTR feature.