# US 4,398,954 A · Microcapsular coating composition containing a hydrophobic silica > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,398,954 A - Document ID: US4398954A - Status: Granted - Kind: A - Application number: 06/195,910 - Filed: 1980-10-10 - Granted: 1983-08-16 - Earliest claimed: 1979-12-31 - Assignees: The Mead Corporation - Inventors: John J. Stolfo - Web page: https://patentgrep.com/patent/US4398954A ## CPC - B41M 5/1243: {Inert particulate additives, e.g. protective stilt materials} - Y10T 428/2984: Microcapsule with fluid core [includes liposome] - B41M: PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING, (correction of typographical errors B41J; processes for applying transfer pictures or the like B44C1/16; fluid media for correction of typographical errors by coating C09D10/00; printing textiles D06P) - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A novel coating composition is disclosed comprising oil-containing microcapsules dispersed in an aqueous continuous phase, which phase also contains finely divided silica particles and a binder for said microcapsules and said silica particles. The silica particles have been treated with an organic material such as an organic silicon compound to give the particles a hydrophobic surface. The coating composition has utility in the manufacture of paper coated with microcapsules. Such paper is characterized by a substantial reduction of specking when used in photocopying apparatus which utilizes a pressure nip to assist transfer of a powder image from a photoreceptor belt to the paper. In a preferred form, the oil contains a color precursor of the electron donating type and the aqueous composition contains stilt material such as starch particles. The coating composition is applied to paper to form a transfer coating on copy paper, said copy paper having utility in the production of multi-part forms. ## Claims ### Claim 1 A coating composition having utility in the manufacture of coated paper, wherein said coating composition contains microcapsules, said paper being characterized by a substantial reduction of specking when used in photocopying apparatus which utilizes a pressure nip between a photoreceptor belt and a transfer roll to transfer a powder image from the photoreceptor belt to the paper, said coating composition comprising microcapsules containing an oil, said microcapsules being dispersed in an aqueous continuous phase said microcapsules having a mean spherical diameter of from 3 to 12 microns, said aqueous continuous phase further containing an amount of surfactant up to about 0.6% solids by weight based on the total solids and finely divided silica particles and a binder for said microcapsules and said silica particles, said silica particles having been modified by treatment with an organic material whereby the surface of said silica is substantially hydrophobic said treated silica particles having a surface area of 50 m.sup.2 /gm or more and being present in said coating composition at a level of from 0.1% to 10.0% by weight based on the total solids of said coating composition. ### Claim 2 (depends on 1) The coating composition of claim 1 wherein said microcapsules contain a chromogenic material in solution in said oil. ### Claim 3 (depends on 2) The coating composition of claim 2 wherein said chromogenic material is a color precursor of the electron donating type. ### Claim 4 (depends on 1) The coating composition of claim 1 wherein said aqueous continuous phase further contains starch particles. ### Claim 5 (depends on 1) The coating composition of claim 1 wherein said organic material is an organic silicon compound. ### Claim 6 (depends on 1) The coating composition of claim 1 wherein said microcapsules have a spherical diameter of about 3 microns to about 8 microns. ### Claim 7 A coating composition having utility in the manufacture of coated paper, wherein said coating composition contains microcapsules, said paper being characterized by a substantial reduction of specking when used in photocopying apparatus which utilizes a pressure nip between a photoreceptor belt and a transfer roll to transfer a powder image from the photoreceptor belt to the paper, said coating composition comprising microcapsules containing an oil, said oil containing in solution therein a chromogenic material, said chromogenic material being a color precursor of the electron donating type, said microcapsules being dispersed in an aqueous continuous phase said microcapsules having a mean spherical diameter of from 3 to 12 microns, said aqueous continuous phase further containing an amount of surfactant up to about 0.6% solids by weight based on the total solids and finely divided silica particles, stilt material and a binder for said microcapsules, said stilt material and said silica particles, said silica particles having been modified by treatment with an organic material whereby the surface of said silica is substantially hydrophobic said treated silica particles having a surface area of 50 m.sup.2 /gm or more and being present in said coating composition at a level of from 0.1% to 10.0% by weight based on the total solids of said coating composition. ### Claim 8 (depends on 7) The coating composition of claim 7 wherein said organic material is an organic silicon compound. ### Claim 9 (depends on 7) The coating composition of claim 7 wherein said microcapsules have a spherical diameter of about 3 microns to about 8 microns. ### Claim 10 (depends on 7) The coating composition of claim 7 wherein said stilt material is starch particles.