Waterproof sound-transmitting sheet and method for manufacturing waterproof sound-transmitting sheet

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.