Diaphragm for electro-acoustic transducer
A diaphragm for electro-acoustic transducers, especially a diaphragm for speakers, and a film for the diaphragm excellent in the formability and the durability in high-output operation are obtained. A diaphragm for electro-acoustic transducers formed of a film that contains a polybiphenyl ether sulfone resin (A) having a specific repetitive unit or contains it and a crystalline resin (B) such as polyaryl ketone resin; and a film for use for the diaphragm.
1. A diaphragm for an electro-acoustic transducer, comprising:
a film having a mean thickness of from 5 to 150 μm,
wherein the film comprises a crystalline resin (B) and a polybiphenyl ether sulfone resin (A) having a repetitive unit of the following structural formula (1):
wherein R 1 to R 4 each represent —O—, —SO 2 —, —S— or C═O, but at least one of R 1 to R 4 is —SO 2 — and at least one of R 1 to R 4 is —O—; Ar 1 , Ar 2 and Ar 3 each represent an arylene group having from 6 to 24 carbon atoms; and a and b each are any of 0 or 1.
2. The diaphragm as claimed in claim 1 , wherein the crystalline resin (B) is a polyaryl ketone resin.
3. The diaphragm as claimed in claim 1 , wherein the crystalline resin (B) is a polyether-ether ketone resin having a repetitive unit of the following structural formula (3):
4. The diaphragm as claimed in claim 1 , wherein the film comprises the polybiphenyl ether sulfone resin (A) and the crystalline resin (B) in a ratio by mass of (A)/(B)=(95 to 55)/(5 to 45).
5. The diaphragm as claimed in claim 1 , wherein the diaphragm is a diaphragm for speakers.
6. The diaphragm as claimed in claim 1 , wherein the polybiphenyl ether sulfone resin (A) includes a polyphenyl sulfone resin having a repetitive unit of the following structural formula (2):
7. The diaphragm as claimed in claim 1 , wherein the glass transition temperature of the polybiphenyl ether sulfone resin (A) is from 180 to 250° C.
8. The diaphragm as claimed in claim 1 , wherein the maximum diameter of the diaphragm is 25 mm.
9. The diaphragm as claimed in claim 1 , wherein the film has a tensile modulus of elasticity of from 1000 MPa to less than 2500 MPa.
10. The diaphragm as claimed in claim 1 , wherein the film has a mean thickness of at most 40 μm.
11. The diaphragm as claimed in claim 1 , wherein the film consists of thermoplastic resins.
12. The diaphragm as claimed in claim 1 , wherein the film does not contain a flame retardant.
13. The diaphragm as claimed in claim 1 , wherein the film is obtained by extruding a thermoplastic composition comprising the polybiphenyl ether sulfone resin (A) and the crystalline resin (B).