# US 11,441,062 B1 · Modified polyvinyl acetate and preparation method and use thereof and oil-based drilling fluid > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,441,062 B1 - Document ID: US11441062B1 - Status: Granted - Kind: B1 - Application number: 17/647,041 - Filed: 2022-01-05 - Granted: 2022-09-13 - Earliest claimed: 2021-09-06 - Assignees: Southwest Petroleum University - Applicants: Southwest Petroleum University - Inventors: Yang Bai; Chunyan Liu; Pingya Luo; Gang Xie; Danchao Huang; Dezhi Liu; Hongbo Li; Daoxiong Li; Chaowei Hu - Web page: https://patentgrep.com/patent/US11441062B1 ## CPC - C09K 8/34: Organic liquids - C08F 18/08: Vinyl acetate - C08F 218/08: Vinyl acetate - C08F 263/04: on to polymers of vinyl acetate - C08F 297/026: {polymerising acrylic acid, methacrylic acid or derivatives thereof} - C08F 2810/50: wherein the polymer is a copolymer and the modification is taking place only on one or more of the monomers present in minority - C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE - C08F: MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS ## Abstract A method of preparing a modified polyvinyl acetate includes subjecting a mixed liquor L1 containing a functional monomer to a first reaction with a first vinyl acetate monomer, followed by adding a first initiator to carry out a second reaction to obtain a mixed liquor L2; subjecting an acrylate monomer, a second vinyl acetate monomer, a second initiator and the mixed liquor L2 to carry out a third reaction to obtain a mixed liquor L3; and subjecting a third initiator and the mixed liquor L3 to carry out a fourth reaction under the air-tight and ultrasonic conditions. The functional monomer is selected from acrylic acid, oleic acid or butenedioic acid. Uses of modified polyvinyl acetate obtained by the method and oil-based drilling fluid containing the modified polyvinyl acetate are also disclosed. ## Claims ### Claim 1 A method of preparing a modified polyvinyl acetate including: (1) subjecting a mixed liquor L1 comprising a functional monomer to a first reaction with a first vinyl acetate monomer, then adding a first initiator to carry out a second reaction to obtain a mixed liquor L2; (2) subjecting an acrylate monomer, a second vinyl acetate monomer, a second initiator and the mixed liquor L2 to carry out a third reaction to obtain a mixed liquor L3; (3) subjecting a third initiator and the mixed liquor L3 to carry out a fourth reaction under the airtight and ultrasonic conditions, subsequently heating products produced by the fourth reaction to a fifth reaction to obtain a mixed liquor L4; (4) subjecting the mixed liquor L4 to a product extraction treatment to prepare a modified polyvinyl acetate; wherein the functional monomer is selected from acrylic acid, oleic acid or butenedioic acid. ### Claim 2 (depends on 1) The method of claim 1, wherein the weight ratio of the first vinyl acetate monomer to the second vinyl acetate monomer is 1:(2-3). ### Claim 3 (depends on 1) The method of claim 1, wherein the weight ratio of the first initiator:the second initiator to the third initiator is 1:(0.2-0.7):(3-4). ### Claim 4 (depends on 1) The method of claim 1, wherein the mass ratio of vinyl acetate monomer comprising the first vinyl acetate monomer and the second vinyl acetate monomer:initiator comprising the first initiator, the second initiator and third initiator:the acrylate monomer:the functional monomer is (1.5-3):(0.05-0.07):(0.3-0.5):(0.1-0.3). ### Claim 5 (depends on 4) The method of claim 4, wherein the mass ratio of vinyl acetate monomer comprising the first vinyl acetate monomer and the second vinyl acetate monomer:initiator comprising the first initiator, the second initiator and third initiator:the acrylate monomer:the functional monomer is (2.6-3):(0.055-0.062):(0.45-0.5):(0.24-0.3). ### Claim 6 (depends on 1) The method of claim 1, wherein the functional monomer is selected from acrylic acid, oleic acid or butenedioic acid; and/or the acrylate monomer is selected from the group consisting of ethyl acrylate, butyl acrylate, isooctyl acrylate, lauryl methacrylate or n-octyl methacrylate; and/or the first initiator, the second initiator and the third initiator are the same and are selected from the aqueous solutions of sodium persulfate, potassium persulfate, ammonium persulfate, hydrogen peroxide or benzoyl peroxide. ### Claim 7 (depends on 1) The method of claim 1, wherein the conditions of the first reaction comprise a temperature of 60-90° C. and a time of 15-20 min; and/or the conditions of the second reaction comprise a temperature of 60-90° C. and a time of 40-60 min; and/or the conditions of the third reaction comprise a temperature of 60-90° C. and a time of 150-240 min; and/or the conditions of the fourth reaction comprise a temperature of 60-90° C. and a time of 30-45 min; and/or the conditions of the fifth reaction comprise a temperature of 90-110° C. and a time of 30-40 min; and/or the airtight and ultrasonic conditions include a frequency of 26,000-35,000 Hz, a temperature of 60-65° C. and a time of 3-8 min. ### Claim 8 (depends on 1) The method of claim 1, wherein the product extraction treatment comprises neutralizing with lime water, washing, drying and grinding. ### Claim 9 (depends on 1) A modified polyvinyl acetate produced with the method of claim 1. ### Claim 10 (depends on 9) The modified polyvinyl acetate of claim 9, wherein the modified polyvinyl acetate has an average particle size of 65-100 nm. ### Claim 11 (depends on 10) The modified polyvinyl acetate of claim 10, wherein the modified polyvinyl acetate has an average particle size of 65-93 nm. ### Claim 12 (depends on 9) An oil-based drilling fluid comprising the modified polyvinyl acetate of claim 9. ### Claim 13 (depends on 12) The oil-based drilling fluid of claim 12, wherein the oil-based drilling fluid comprising: 100 parts by weight of base fluid, 15-20 parts by weight of water, 3-6 parts by weight of organic soil, 1-3 parts by weight of emulsifier, 2-4 parts by weight of wetting agent, 1-4 parts by weight of modified polyvinyl acetate, 15-35 parts by weight of weighting agent, 3-5 parts by weight of filtrate reducer, 1-3 parts by weight of calcium oxide. ### Claim 14 (depends on 13) The oil-based drilling fluid of claim 13, wherein the base fluid is selected from No. 3 white oil, No. 5 white oil or diesel oil. ### Claim 15 (depends on 14) The oil-based drilling fluid of claim 14, wherein the base fluid is No. 3 white oil. ### Claim 16 (depends on 13) The oil-based drilling fluid of claim 13, wherein the organic soil is an oleophilic clay prepared through an interaction of a hydrophilic bentonite and a quaternary ammonium salt cationic surfactant. ### Claim 17 (depends on 13) The oil-based drilling fluid of claim 13, wherein the wetting agent is lecithin; and/or the weighting agent is at least one selected from the group consisting of API barite, ultrafine barium sulfate, magnetite powder, titaniferous powder, and trimanganese tetroxide. ### Claim 18 (depends on 13) The oil-based drilling fluid of claim 13, wherein the API barite is mixed with ultrafine barium sulfate in a mass ratio (5-7):(2-3).