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US 4,927,728 AGranted
Carrier particles for use in a two-component dry-type developer
AssigneeRicoh Company, Ltd.
InventorsTetsuo Isoda, Yoichiro Watanabe, Nobuhiro Nakayama, Mitsuo Aoki
Life of this patent
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Abstract
The disclosure describes carrier particles for use in a two-component dry-type developer, consisting of core particles which are coated with a silicone resin hardened by an organic tin catalyst.
Claims6
Carrier particles for use in two-component dry-type developers for electrophotography, comprising:
- core particles coated with a hardened silicone resin having a three-dimensional network structure comprised of Si-O-Si bonds, said core particles being made of a material selected from the group consisting of a magnetic metal, a non-magnetic metal and a non-metallic material, with the particle size thereof being in the range of 30 .mu.m to 1,000 .mu.m, said carrier particles having been prepared by dissolving an organosiloxane capable of forming said silicone resin and an organic tin catalyst capable of catalyzing hardening of said silicone resin in an organic solvent to form a silicone varnish, then coating said core particles with said varnish and drying said varnish to form coatings on said core particles, then heating said coated core particles at a temperature in the range of about 100.degree. C. to about 250.degree. C. to harden the silicone resin, said organic tin catalyst being selected from the group consisting of:
- (No. 1) R.sub.2 Sn(OCOR').sub.2 wherein R and R' each represent an alkyl group of C.sub.1 .about.C.sub.12. ##STR3##
Carrier particles for use in two-component dry-type developers for electrophotography, comprising:
- core particles having a particle size in the range of from 30 .mu.m to 1000 .mu.m and coated with a layer consisting essentially of a hardened silicone resin having a three-dimensional network structure consisting essentially of Si-O-Si bonds, said carrier particles having been prepared by dissolving methylpolysiloxane capable of forming said silicon resin and an organic tin catalyst capable of catalyzing hardening of said methylpolysiloxane in an organic solvent to form a silicone varnish, then coating said core particles with said varnish and drying said varnish to form coatings on said core particles, then heating said coated core particles at a temperature in the range of about 100.degree. C. to about 250.degree. C. to harden the silicone resin, said organic tin catalyst being selected from the group consisting of:
- R.sub.2 Sn(OCOR').sub.2 wherein R and R' each represent an alkyl group of C.sub.1 to C.sub.12. ##STR5##
Dependencies are inferred from the claim text.