Abstract: Provided is a porous polytetrafluoroethylene membrane in which an absolute value of a difference in lightness between one principal surface and the other principal surface is 1.0 or more, where the lightness is lightness L* of CIE 1976 (L*, a*, b*) color space specified in JIS Z8781-4: 2013. The porous polytetrafluoroethylene membrane may be colored black or gray. The porous polytetrafluoroethylene membrane provided can have properties with a reduced coloring-induced deterioration.

Abstract: Provided is a porous polytetrafluoroethylene membrane in which an absolute value of a difference in lightness between one principal surface and the other principal surface is 1.0 or more, where the lightness is lightness L* of CIE 1976 (L*, a*, b*) color space specified in JIS Z8781-4: 2013. The porous polytetrafluoroethylene membrane may be colored black or gray. The porous polytetrafluoroethylene membrane provided can have properties with a reduced coloring-induced deterioration.

Abstract: The conversion element member of the present disclosure includes: a conversion element having an opening capable of functioning as a ventilation port and/or a sound-transmitting port; and a waterproof membrane. The conversion element has an outer surface provided with the opening. The waterproof membrane is joined, at a joining portion thereof, to the outer surface of the element so as to cover the opening, the joining portion having a shape surrounding the opening when viewed in a direction perpendicular to the outer surface. The waterproof membrane has a non-joining portion defined as a portion surrounded by the joining portion when viewed in the direction, the non-joining portion having a region overlapping the outer surface when viewed in the direction. A spacing distance D1 between the membrane and the outer surface in the region is 0.01 mm to X mm, where X represents, in an indentation test on the waterproof membrane.

Abstract: Provided is a waterproof cover having a waterproof membrane, and a PSA sheet laminated peripherally to the waterproof membrane. The PSA sheet comprises a PSA layer bonded to the waterproof membrane. The PSA layer is formed of a PSA having a storage modulus G? of 53000 Pa or higher at 40° C.

Abstract: A waterproof membrane of the present disclosure has an insertion loss of 5.0 dB or less for sound with a frequency of 1 kHz, and an insertion loss of 5.0 dB or less for sound with a frequency of 10 kHz when a permeation region for sound of the waterproof membrane has an area of 1.3 mm2. The waterproof membrane of the present disclosure can cope with further size reduction of the permeation region. A waterproof member of the present disclosure includes the above-mentioned waterproof membrane of the present invention and a support member joined to the waterproof membrane.

Abstract: A waterproof membrane of the present disclosure has an insertion loss of 5.0 dB or less for sound with a frequency of 1 kHz, and an insertion loss of 5.0 dB or less for sound with a frequency of 10 kHz when a permeation region for sound of the waterproof membrane has an area of 1.3 mm2. The waterproof membrane of the present disclosure can cope with further size reduction of the permeation region. A waterproof member of the present disclosure includes the above-mentioned waterproof membrane of the present invention and a support member joined to the waterproof membrane.

Abstract: A method for producing a thermally conductive sheet, having a thermal conductivity in a direction perpendicular to a thickness direction of 10 W/m·K or more, includes a preparing step of preparing a resin composition containing a resin and a thermally conductive inorganic particle and a sheet forming step of forming a sheet by further increasing the viscosity after hot-pressing the resin composition to be brought from a melted state into a semi-solid state.

Abstract: A polyamide-imide resin composition according to embodiment of the present invention, including a polyamide-imide resin obtained by causing acid components (A) containing a dimer acid and a polyisocyanate component (B) to react with each other, wherein a ratio of the dimer acid in the acid components (A) is 3 mol % to 55 mol %.

Abstract: A polyamide-imide resin composition according to embodiment of the present invention, including a polyamide-imide resin obtained by causing acid components (A) containing a dimer acid and a polyisocyanate component (B) to react with each other, wherein a ratio of the dimer acid in the acid components (A) is 3 mol % to 55 mol %.