# US 4,393,103 A · Erasable dense paper and improved method of manufacturing > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,393,103 A - Document ID: US4393103A - Status: Granted - Kind: A - Application number: 06/297,104 - Filed: 1981-08-28 - Granted: 1983-07-12 - Earliest claimed: 1981-08-28 - Inventors: William G. Louden - Web page: https://patentgrep.com/patent/US4393103A ## CPC - D21H 17/12: Organo-metallic compounds - Y10T 428/31895: Paper or wood - Y10T 428/31906: Ester, halide or nitrile of addition polymer - D21H: PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A paper which affords complete erasability of typewriter images is disclosed. The paper comprises a web of cellulosic fibers and a blend of a rigid polymeric material and a compatible filler together with a small but effective amount of tin carried by the web. A process for manufacturing the paper is also disclosed. ## Claims ### Claim 1 A process for manufacturing dense paper comprising the steps, performed in the following sequence, of: advancing a web of paper having a dry uncalendered density in a range of between about 7 to about 14 lbs./mil.; applying to the advancing web an aqueous dispersion containing a blend of a rigid polymeric material and an inorganic filler, said blend consisting essentially of from about 35 to about 90% of said polymeric material, from about 10 to about 65% of said inorganic filler, and an organic compound of tin in a range of about 0.10% to about 2.0%, said percentages being by weight based on the non-tin portion of the weight of the blend, said rigid polymeric material having a glass transition temperature in a range of between about 15 to about 60.degree. C.; removing the excess dispersion from said web; and heating said web after the excess dispersion has been removed to fuse said blend to said web so that the resulting paper comprises in a range of between about 8.5% to about 50%, by weight of the blend, said weight being based on the dry weight of the web. ### Claim 2 (depends on 1) The process according to claim 1 wherein said organic compound of tin is in a range of about 0.10% to about 2.0%, by weight, based on the combined weight of the polymeric material and filler. ### Claim 3 (depends on 2) The process according to claim 2 wherein said organic compound of tin includes dialkyl tin dicarboxylates. ### Claim 4 (depends on 3) The process according to claim 3 wherein said dialkyl tin dicarboxylates include an alkyl group having at least four carbon atoms. ### Claim 5 (depends on 4) The process according to claim 4 wherein said alkyl group has about eight carbon atoms. ### Claim 6 (depends on 3) The process according to claim 3 wherein said dialkyl tin dicarboxylates include a carboxyl group having a chain of at least twelve carbon atoms. ### Claim 7 (depends on 3) The process according to claim 3 wherein said dialkyl tin dicarboxylates are selected from the group consisting of dioctyl tin dilaurate, dibutyl tin distearate, dibutyl tin di 2-ethyl-hexoate, dibutyl tin di B-mercapto propionate, dibutyl tin dilaurate, dibutyl tin diacetate, and dioctyl tin di b-isooctyl mercapto acetate. ### Claim 8 (depends on 1) The process according to claim 1 wherein said compound of tin is selected from the group consisting of dilauryl tin dichloride and tri n-butyl tin oxide. ### Claim 9 (depends on 1) The process according to claim 1 wherein said blend is impregnated in said web. ### Claim 10 (depends on 1) The process according to claim 1 wherein said blend is carried predominately on the surface of said web. ### Claim 11 (depends on 1) The process according to claim 1 wherein the density of said paper web prior to application of said blend is in a range of between about 8.5 to about 10.5 lbs./mil. ### Claim 12 (depends on 1) The process according to claim 1 wherein said web is substantially free of sizing prior to application of said blend. ### Claim 13 (depends on 1) The process according to claim 1 wherein said polymeric material of said blend is selected from the group of materials consisting of polyvinyl acetate, polyacrylate, and polyvinyl chloride. ### Claim 14 (depends on 1) The process according to claim 1 wherein said inorganic filler is selected from the group of fillers consisting of clay, calcium carbonate, mica, and talc. ### Claim 15 (depends on 1) The process according to claim 1 wherein said aqueous dispersion includes between about 12.5 and 60%, by weight, of said blend, based on the total weight of said dispersion.