# US 2014/0150691 A1 · Sulfite softwood based cellulose triacetate for lcd films > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0150691 A1 - Document ID: US20140150691A1 - Status: Published application - Kind: A1 - Application number: 14/182,606 - Filed: 2014-02-18 - Published: 2014-06-05 - Earliest claimed: 2010-02-12 - Assignees: Eastman Chemical Company - Applicants: Eastman Chemical Company - Inventors: Darryl Aubrey Godfrey; Laurel Leigh Reitfort - Web page: https://patentgrep.com/patent/US20140150691A1 ## CPC - C08L 1/12: Cellulose acetate - C08J 5/18: Manufacture of films or sheets - C08J 2301/12: Cellulose acetate - G02F 1/133528: {Polarisers} - C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06) - C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29) - G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS ## Abstract The invention provides a way of using cellulose triacetate (CTA) made from softwood pulp to make films suitable for use in liquid crystal displays (LCDs). It has been surprisingly found that a combination of certain additives in the film casting dope and of metal and sulfur content of the CTA allow a softwood CTA to exhibit peeling characteristics from the casting substrate that are similar to those of lint-based CTA of similar sulfur content. The additives include a combination of acid scavengers and chelating agents. ## Claims ### Claim 1 A dope for making a solvent-cast film comprising: (a) cellulose triacetate made from sulfite-process softwood pulp and having less than 35 ppm of sulfur and less than 2 weight percent of xylose, both based on the weight of the cellulose triacetate, and a molar ratio of metals to sulfate of at least 3:1; (b) an acid scavenger; (c) a chelating agent; and (d) a solvent. ### Claim 2 (depends on 1) The dope according to claim 1, wherein the cellulose triacetate has 8 to 15 ppm of sulfur. ### Claim 3 (depends on 1) The dope according to claim 1, wherein the cellulose triacetate has 0.5 to 0.6 weight percent of xylose. ### Claim 4 (depends on 1) The dope according to claim 1, wherein the cellulose triacetate comprises at least 98 weight percent of a-cellulose. ### Claim 5 (depends on 1) The dope according to claim 1, which comprises from 15 to 23 weight percent of the cellulose triacetate. ### Claim 6 (depends on 1) The dope according to claim 1, which comprises from 0.1 to 1 weight percent of the acid scavenger. ### Claim 7 (depends on 1) The dope according to claim 1, wherein the acid scavenger comprises epoxidized plant oil. ### Claim 8 (depends on 1) The dope according to claim 1, which comprises 0.01 to 0.1 weight percent of the chelating agent. ### Claim 9 (depends on 1) The dope according to claim 1, wherein the chelating agent comprises citric acid. ### Claim 10 (depends on 1) The dope according to claim 1, wherein the solvent comprises methylene chloride and from 6 to 20 weight percent of at least one of methanol and ethanol, based on the weight of the solvent. ### Claim 11 (depends on 1) The dope according to claim 1, for making a solvent-cast film comprising: (a) having 8 to 15 ppm of sulfur, 0.8 weight percent or less of xylose, and at least 98 weight percent of a-cellulose, all based on the weight of the cellulose triacetate; (b) the acid scavenger comprising epoxidized plant oil; and (c) the chelating agent comprising citric acid. ### Claim 12 A film comprising: (a) cellulose triacetate made from sulfite-process softwood pulp and having less than 35 ppm of sulfur and less than 2 weight percent of xylose, both based on the weight of the cellulose triacetate, and a molar ratio of metals to sulfate of at least 3:1; (b) an acid scavenger; and (c) a chelating agent. ### Claim 13 (depends on 12) The film according to claim 12 comprising: (a) 8 to 15 ppm of sulfur, 0.8 weight percent or less of xylose, and at least 98 weight percent of a-cellulose, all based on the weight of the cellulose triacetate; (b) the acid scavenger comprising epoxidized plant oil; and (c) the chelating agent comprising citric acid. ### Claim 14 (depends on 13) The film according to claim 13, which has a thickness of 20 to 100 microns. ### Claim 15 (depends on 13) The film according to claim 13, which comprises from 1 to 5 weight percent of the acid scavenger. ### Claim 16 (depends on 13) The film according to claim 13, which comprises 0.1 to 0.5 weight percent of the chelating agent. ### Claim 17 (depends on 13) The film according to claim 13, which comprises from 80 to 95 weight percent of the cellulose triacetate. ### Claim 18 (depends on 1) A method of preparing the dope according to claim 1, which comprises: (a) combining the cellulose triacetate, the acid scavenger, and the solvent together to form a solution; and (b) adding the chelating agent to the solution from step (a) to form the dope. ### Claim 19 (depends on 11) A method of preparing the dope according to claim 11, which comprises: (a) combining the cellulose triacetate, the acid scavenger, and the solvent together to form a solution; and (b) adding the chelating agent to the solution from step (a) to form the dope. ### Claim 20 (depends on 1) A method of making a film comprising: (a) casting the dope according to claim 1 onto a continuously moving support to form a cast film on the support; (b) partially drying the cast film; (c) separating the cast film from the support; and (d) drying the separated film. ### Claim 21 (depends on 11) A method of making a film comprising: (a) casting the dope according to claim 11 onto a continuously moving support to form a cast film on the support; (b) partially drying the cast film; (c) separating the cast film from the support; and (d) drying the separated film. ### Claim 22 (depends on 12) A polarizer plate for a liquid crystal display comprising the film according to claim 12. ### Claim 23 (depends on 13) A polarizer plate for a liquid crystal display comprising the film according to claim 13. ### Claim 24 (depends on 12) An optical lens comprising the film according to claim 12. ### Claim 25 (depends on 13) An optical lens comprising the film according to claim 13. ### Claim 26 (depends on 14) The film according to claim according to claim 14, wherein the film has a planar retardation of about −5 nm to about 5 nm measured at 589 nm and normalized to a 60 micron film thickness.