Jsp Corporation

Satoshi Iwasaki

Takeshi Aoki

Yoshihisa Ishihara

Hisao Tokoro

Satoru Shioya

Yoshiaki Momose

Hirotoshi Kakuta

Kazuhiko Morita

Seiji Takahashi

Shinpei Arita

A method of producing a composite sheet having a foam layer of a first polyolefin-based resin and a surface layer of a second polyolefin-based resin provided on at least one side of the foam layer and containing a polymeric antistatic agent. The method includes coextruding through die a first melt containing the first polyolefin-based resin and a physical blowing agent and a second melt containing the second polyolefin-based resin, the polymeric antistatic agent and a volatile plasticizer to obtain the composite sheet. The amount of the polymeric antistatic agent is 4 to 100 parts by weight per 100 parts by weight of the second polyolefin-based resin and the amount of the volatile plasticizer is 5 to 50 parts by weight per 100 parts by weight of a total amount of the second polyolefin-based resin and the polymeric antistatic agent. The second polyolefin-based resin has a crystallization temperature of Ta [&#xb0; C.] and a melt viscosity of Ma [Pa&#xb7;s], while the polymeric antistatic agent has a crystallization temperature of Tb [&#xb0; C.] and a melt viscosity of Mb [Pa&#xb7;s], wherein Ta, Tb, Ma and Mb satisfy the following conditions:&#x3c;(&#xb0; C.)Mb&#x3c;Ma.

Method of producing composite sheet having polyolefin foam layer

The present invention provides a speaker unit comprising a diaphragm of 0.5 to 10 mm thick aromatic polycarbonate with a density of 0.03 to 0.6 g/cm , and a mechanism for driving the diaphragm. The aromatic polycarbonate used for the diaphragm is preferably derived from bisphenol with a viscosity average molecular weight of 25,000 to 70,000. The invention further provides a speaker system comprising such a speaker unit attached to a cabinet and a method for manufacturing the speaker diaphragm.

Speaker unit, speaker system, and speaker diaphragm manufacturing method

A composite sheet having a first, foamed polycarbonate resin layer and a second, non-foamed polycarbonate resin layer provided on at least one surface of the first layer and having a melt tension of at least 2.45 cN at 250&deg; C.

Composite sheet having foamed polycarbonate resin layer and non-foamed polycarbonate resin layer

A composite material having a skin layer, an intermediate, cushioning layer provided on one side of the skin layer, and a backing layer provided on the cushioning layer, wherein the backing layer is made of a non-crosslinked polypropylene resin foam and having a melting point MB in the range of 130-170.degree. C., wherein the cushioning layer is a crosslinked polypropylene resin foamed sheet having a gel fraction of 20-70% by weight. The cushioning layer has an endothermic peak in DSC curve at a peak temperature of PC which is in the range of 130-170.degree. C. and which is not smaller than (MB-15).degree. C. but not greater than (MB+10).degree. C. The endothermic peak has such an area at temperatures higher than MB that corresponds to a calorific value in the range of 3-30 J/g. The backing layer may be formed by expansion molding of expanded polypropylene particles within a mold cavity in which a laminate of the skin layer and the cushioning layer is placed in position.

Growing community of inventors

Utsunomiya, Japan

Satoshi Iwasaki