Sound-absorbing membrane, sound absorbing material, and methods of manufacture thereof

1. A sound-absorbing membrane comprising:

a base sheet made of a nonwoven fabric having an airflow resistance of 0.015 to 0.04 kPa·s/m; and

a resin film covering one surface of the base sheet, the resin film made of a thermosetting resin in a semi-cured state,

wherein:

fillers made of powder having an average particle diameter of 1 to 100 μm are dispersed in the resin film;

the sound-absorbing membrane has a whole airflow resistance of 0.2 to 5.0 kPa·s/m; and

in the resin film, a mixing ratio of the fillers/the thermosetting resin is from 55/45 to 70/30 in a solid content ratio.

2. The sound-absorbing membrane according to claim 1 , wherein the nonwoven fabric used for the base sheet has a mass per unit area of 10 g/m 2 to 120 g/m 2 and a thickness of 0.1 to 2.0 mm.

3. The sound-absorbing membrane according to claim 1 , wherein the thermosetting resin used for the resin film is a resorcinol resin or an ester bond-forming curable thermosetting acrylic resin.

4. A sound-absorbing material comprising:

a sound absorbing base sheet made of a porous material; and

the sound-absorbing membrane according to claim l that is laminated on one surface or both surfaces of the sound absorbing base sheet such that the resin film faces the sound absorbing base sheet,

wherein the sound-absorbing material has a predetermined shape.

5. A method of manufacturing the sound-absorbing membrane according to claim 1 ,

the method comprising the steps of:

applying a coating liquid obtained by dispersing the fillers in a liquid of the thermosetting resin in an uncured state onto the base sheet made of the nonwoven fabric having the airflow resistance of 0.015 to 0.04 kPa·s/m such that an applied amount of the coating liquid is within a range of 10 g/m 2 to 50 g/m 2 in terms of a solid content; and

heating and drying the base sheet onto which the coating liquid is applied, at a predetermined temperature so as to bring the thermosetting resin into the semi-cured state, to form the resin film.

6. The method of manufacturing the sound-absorbing membrane according to claim 5 , wherein:

the thermosetting resin is the resorcinol resin or the ester bond-forming curable thermosetting acrylic resin; and

the base sheet is heated and dried at a temperature of 120° C. or more and 160° C. or less.

7. A method of manufacturing a sound-absorbing material,

the method comprising the steps of:

laminating the sound-absorbing membrane according to claim 1 on one surface or both surfaces of a sound absorbing base sheet made of a porous material such that the resin film faces the sound absorbing base sheet, to obtain a sound absorbing original fabric formed into a sheet shape and including the sound-absorbing membrane and the sound absorbing base sheet; and

thereafter subjecting the sound absorbing original fabric to hot press forming at a temperature of 180° C. or more, to bring the thermosetting resin of the resin film into a cured state while forming the sound absorbing original fabric into a predetermined shape.

8. A sound-absorbing membrane comprising:

a base sheet made of a nonwoven fabric having a airflow resistance 0.015 to 0.04 kPa·s/m; and

a resin film covering one surface of the base sheet, the resin film made of a thermosetting resin in a semi-cured state,

wherein:

fillers made of powder having an average particle diameter of 1 to 100 μm are dispersed in the resin film; and

the sound-absorbing membrane has a whole airflow resistance of 0.2 to 5.0 kPa·s/m,

wherein the nonwoven fabric used for the base sheet has a mass per unit area of 10 g/m 2 to 120 g/m 2 and a thickness range of at least 0.1 mm to less than 2.0 mm, in the resin film, a mixing ratio of the fillers/the thermosetting resin is from 55/45 to 70/30 in a solid content ratio.

9. A sound-absorbing material comprising:

a sound absorbing base sheet made of a porous material; and

the sound-absorbing membrane according to claim 8 that is laminated on one surface or both surfaces of the sound absorbing base sheet such that the resin film faces the sound absorbing base sheet,

wherein the sound-absorbing material has a predetermined shape.

10. A method of manufacturing the sound-absorbing membrane according to claim 8 ,

the method comprising the steps of:

applying a coating liquid obtained by dispersing the fillers in a liquid of the thermosetting resin in an uncured state onto the base sheet made of the nonwoven fabric having the airflow resistance of 0.015 to 0.04 kPa·s/m such that an applied amount of the coating liquid is within a range of 10 g/m 2 to 50 g/m 2 in terms of a solid content; and

heating and drying the base sheet onto which the coating liquid is applied, at a predetermined temperature so as to bring the thermosetting resin into the semi-cured state, to form the resin film.

11. The method of manufacturing the sound-absorbing membrane according to claim 8 , wherein:

the thermosetting resin is the resorcinol resin or the ester bond-forming curable thermosetting acrylic resin; and

the base sheet is heated and dried at a temperature of 120° C. or more and 160° C. or less.

12. A method of manufacturing a sound-absorbing material,

the method comprising the steps of:

laminating the sound-absorbing membrane according to claim 8 on one surface or both surfaces of a sound absorbing base sheet made of a porous material such that the resin film faces the sound absorbing base sheet, to obtain a sound absorbing original fabric formed into a sheet shape and including the sound-absorbing membrane and the sound absorbing base sheet; and

thereafter subjecting the sound absorbing original fabric to hot press forming at a temperature of 180° C. or more, to bring the thermosetting resin of the resin film into a cured state while forming the sound absorbing original fabric into a predetermined shape.