Waterproof sound-transmitting sheet and method for manufacturing waterproof sound-transmitting sheet
A waterproof sound-transmitting sheet is disclosed. The waterproof sound-transmitting sheet comprises: a waterproof sound-transmitting layer having a waterproofing function and configured to transmit a sound; a first adhesive layer attached to a first surface of the waterproof sound-transmitting layer; and a second adhesive layer attached to a second surface of the waterproof sound-transmitting layer, opposite to the first surface, wherein the waterproof sound-transmitting layer comprises: a pore-free layer having no pores; and a porous layer laminated on the pore-free layer and containing pores.
1 . A waterproof sound-transmitting sheet comprising:
a waterproof sound-transmitting layer having a waterproofing function and configured to transmit a sound;
a first adhesive layer attached to a first surface of the waterproof sound-transmitting layer; and
a second adhesive layer attached to a second surface of the waterproof sound-transmitting layer, which is opposite to the first surface,
wherein the waterproof sound-transmitting layer includes:
a pore-free layer having no pores; and
a porous layer laminated on the pore-free layer and including pores,
wherein the porous layer has a web structure in which a plurality of fibers generated as an electrospinning solution containing a polymer material and a solvent is electrospun are laminated by intersecting each other, and
the pore-free layer, which is a part of the porous layer, has a form in which the plurality of fibers having the web structure are entangled with each other and pores of the porous layer are blocked as a part of the porous layer is dissolved by the solvent,
wherein the pores of the porous layer are formed by a space between fibers in the plurality of fibers,
wherein the porous layer includes:
fibers made of a polymer material; and
beads made of the polymer material and having a lump shape,
wherein the beads are formed at both ends of each of the fibers,
wherein a ratio of the fibers and the beads in the porous layer is in a range of 3:7 to 7:3, and
wherein the ratio is a ratio of areas of the fibers and areas of the beads to a total area of the porous layer or a ratio of weights of the fibers and weights of the beads to a total weight of the porous layer, and
wherein the polymer material includes thermoplastic polyurethane (TPU) and polyvinylidene fluoride (PVDF), the polyvinylidene fluoride (PVDF) being present in an amount of up to 20 wt % based on a total weight of the polymer material.
2 . The waterproof sound-transmitting sheet of claim 1 , wherein a thickness of the pore-free layer is greater than or equal to a thickness of the porous layer.
3 . The waterproof sound-transmitting sheet of claim 2 , wherein a ratio of the thickness of the pore-free layer and the porous layer is 1:1 to 1:19.