Waterproof sound-permeable membrane, waterproof sound-permeable member, and electronic device
The waterproof sound-permeable membrane of the present disclosure is a waterproof sound-permeable membrane adapted to permit passage of sound and prevent ingress of water. The air permeability of the waterproof sound-permeable membrane, as expressed by Gurley number, is 20 seconds/100 mL or more. The water entry pressure of the waterproof sound-permeable membrane is 500 kPa or more. When a tensile strength at break of the waterproof sound-permeable membrane in a MD direction is denoted by T 1 and a tensile strength at break of the waterproof sound-permeable membrane in a TD direction orthogonal to the MD direction is denoted by T 2 , a strength ratio (T 1 /T 2 ) is in a range of 0.5 to 2.0.
1. A waterproof sound-permeable membrane adapted to permit passage of sound and prevent ingress of water, wherein
an air permeability of the waterproof sound-permeable membrane, as expressed by Gurley number, is 20 seconds/100 mL or more,
a water entry pressure of the waterproof sound-permeable membrane is 500 kPa or more,
when a tensile strength at break of the waterproof sound-permeable membrane in a MD direction is denoted by T 1 and a tensile strength at break of the waterproof sound-permeable membrane in a TD direction orthogonal to the MD direction is denoted by T 2 , a strength ratio (T 1 /T 2 ) is in a range of 0.5 to 2.0, and
the waterproof sound-permeable membrane is endurable against a continuous water pressure loading test in which the membrane is continuously exposed to a water pressure of 500 kPa for 10 minutes.
2. The waterproof sound-permeable membrane according to claim 1 , wherein
the waterproof sound-permeable membrane is formed of polytetrafluoroethylene.
3. The waterproof sound-permeable membrane according to claim 2 , wherein
the waterproof sound-permeable membrane is oriented both in the MD direction and in the TD direction.
4. The waterproof sound-permeable membrane according to claim 1 , wherein
the strength ratio (T 1 /T 2 ) is in a range of 0.5 to 1.25.
5. The waterproof sound-permeable membrane according to claim 1 , wherein
at least one selected from the tensile strength T 1 and the tensile strength T 2 is 30 MPa or more.
6. The waterproof sound-permeable membrane according to claim 1 , wherein
the air permeability of the waterproof sound-permeable membrane, as expressed by Gurley number, is 10000 seconds/100 mL or more.
7. The waterproof sound-permeable membrane according to claim 1 , wherein
the air permeability of the waterproof sound-permeable membrane, as expressed by Gurley number, is 20 to 300 seconds/100 mL.
8. The waterproof sound-permeable membrane according to claim 1 , wherein
an insertion loss at 1 kHz measured for the waterproof sound-permeable membrane is 13 dB or less when the waterproof sound-permeable membrane has a circular sound-permeable region with a diameter of 1.5 mm.
9. The waterproof sound-permeable membrane according to claim 1 , wherein
the waterproof sound-permeable membrane has a surface density of 1 to 30 g/m 2 .
10. The waterproof sound-permeable membrane according to claim 1 , wherein
the waterproof sound-permeable membrane has a surface density of 1 to 25 g/m 2 .
11. The waterproof sound-permeable membrane according to claim 1 , wherein
the waterproof sound-permeable membrane is subjected to a coloring treatment.
12. A waterproof sound-permeable member comprising:
the waterproof sound-permeable membrane according to claim 1 ; and
a bonding layer placed on a surface of the waterproof sound-permeable membrane.
13. An electronic device comprising:
a sound transducing part that performs conversion between an electrical signal and sound;
a housing enclosing the sound transducing part and having an opening located between the sound transducing part and the outside of the housing; and
the waterproof sound-permeable membrane according to claim 1 , the waterproof sound-permeable membrane being attached to the housing to cover the opening.
14. An electronic device comprising:
a sound transducing part that performs conversion between an electrical signal and sound;
a housing enclosing the sound transducing part and having an opening located between the sound transducing part and the outside of the housing; and
the waterproof sound-permeable member according to claim 12 , the waterproof sound-permeable member being attached to the housing to cover the opening.
15. The waterproof sound-permeable membrane according to claim 1 , wherein
an amount of change in an insertion loss at 1 kHz of the waterproof sound-permeable membrane during the continuous water pressure loading test is 5.2 dB or less, the insertion loss being a value when the water sound-permeable membrane has a circular sound-permeable region with a diameter of 1.5 mm.
16. The waterproof sound-permeable membrane according to claim 1 , wherein
the strength ratio (T 1 /T 2 ) is in a range of 0.9 to 2.0.
17. The waterproof sound-permeable membrane according to claim 1 , wherein
the strength ratio (T 1 /T 2 ) is in a range of 0.9 to 1.92.
18. The waterproof sound-permeable membrane according to claim 1 , wherein
the air permeability of the waterproof sound-permeable membrane, as expressed by Gurley number, is 68 to 300 seconds/100 mL.
19. The waterproof sound-permeable membrane according to claim 1 , wherein
the water entry pressure of the waterproof sound-permeable membrane is 747 kPa or more, and the thickness of the waterproof sound-permeable membrane is 1 μm to 13 μm.
20. The waterproof sound-permeable membrane according to claim 1 , wherein
the waterproof sound-permeable membrane is subjected to a surface modification treatment for improving a bond strength.