# US 5,700,576 A · UV-curable scratch-resistant varnish having a thickener which becomes bound in the composition of the varnish by polymerization > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,700,576 A - Document ID: US5700576A - Status: Granted - Kind: A - Application number: 08/609,771 - Filed: 1996-03-04 - Granted: 1997-12-23 - Earliest claimed: 1995-03-02 - Assignees: Roehm GmbH Chemische Fabrik - Inventors: Manfred Brehm; Rolf Neeb; Wolfgang Scharnke; Volker Kerscher - Web page: https://patentgrep.com/patent/US5700576A ## CPC - C09D 4/06: {Organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond} in combination with a macromolecular compound other than an unsaturated polymer of groups C09D159/00 - C09D187/00 - Y10T 428/31507: Of polycarbonate - Y10T 428/31909: Next to second addition polymer from unsaturated monomers - C09D: COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR (cosmetics A61K; processes for applying liquids or other fluent materials to surfaces, in general, B05D; staining wood B27K5/02; glazes or vitreous enamels C03C; natural resins, French polish, drying-oils, driers, turpentine, per se, C09F; polishing compositions other than French polish, ski waxes C09G; adhesives or use of materials as adhesives C09J; materials for sealing or packing joints or covers C09K3/10; materials for stopping leaks C09K3/12; processes for the electrolytic or electrophoretic production of coatings C25D) - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A coating agent for producing scratch-resistant coatings on plastic articles, which comprises: (1) 1-30 wt. % of a prepolymer, as a thickener (IP thickener), which prepolymer is bound in the composition of the coating by polymerization; (2) 20-80 wt. % of multifunctional acrylates, multifunctional methacrylates or mixtures thereof; (3) 5-75 wt. % of a thinner; (4) 0.01-10 wt. % of a UV-initiator; (5) 0-20 wt. % of customary additives; wherein the prepolymer (1) is obtained by radical polymerization of: (a) 90-99 wt. % of C.sub.1 -C.sub.8 -alkyl esters of acrylic- or methacrylic acid; and (b) 1-10 wt. % of a sulfur-containing regulator having at least three thiol groups. The coating system is distinguished by high scratch-resistance and good weatherability. ## Claims ### Claim 1 A coating agent for producing scratch-resistant coatings on plastic articles, which comprises: (1) 1-30 wt. % of a prepolymer, as an in-polymerizable, thickener which prepolymer is bound in the composition of the coating by polymerization; (2) 20-80 wt. % of multifunctional acrylates, multifunctional methacrylates, or mixtures thereof; (3) 5-75 wt. % of a thinner; (4) 0.01-10 wt. % of an ultraviolet initiator; (5) 0-20 wt. % of customary additives, wherein the prepolymer (1) is obtained by radical polymerization of: (a) 90-99 wt. % of C.sub.1 -C.sub.8 -alkyl esters of acrylic- or methacrylic acid; and (b) 1-10 wt. % of a sulfur-containing regulator having at least three thiol groups. ### Claim 2 (depends on 1) The coating agent according to claim 1 wherein methyl methacrylate and butyl methacrylate as monomers (a) are polymerized in the preparation of prepolymer (1). ### Claim 3 (depends on 1) The coating agent according to claim 1, wherein the sulfur-containing regulator (b) has four thiol groups in the molecule. ### Claim 4 (depends on 3) The coating agent according to claim 3, wherein the sulfur-containing regulator (b) is pentaerythritol tetrakis(2-mercaptoacetate). ### Claim 5 (depends on 1) The coating agent according to claim 1, wherein said multifunctional (meth)acrylate is ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, 4-thioheptanol 2,6-di(meth)acrylate, tetraethylene glycol di(meth)acrylate, pentanediol di(meth)acrylate, hexanediol di(meth)acrylate, 2,2-di(hydroxymethyl)-1-butanol tri(meth)acrylate, di›2,2-di-(hydroxymethyl)-1-butanol! tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, pentaerythritol tetraacrylate, and the like. ### Claim 6 (depends on 1) The coating agent according to claim 1, wherein said sulfur containing regulator (b) is a member selected from the group consisting of 1,2,6-hexanetriol trithioglycolate, 2,2-di(hydroxymethyl)-1-propanol tris(2-mercaptoacetate), pentaerythritol tetrakis(2-mercaptoacetate), 2,2-di-(hydroxymethyl)-1-propanol tris(3-mercaptopropanoate), pentaerythritol tetrakis(3-mercaptopropanoate), 2,2-di-(hydroxymethyl)-1-butanol tris(3-mercaptoacetate), 2,2-di-(hydroxymethyl)-1-butanol tris(3 mercaptopropanoate), 1,1,1-propanetriyl tris(2-mercaptoacetate), 1,1,1-propanetriyl tris(3-mercaptopropanoate), and dipentaerythritol hexakis(3-mercaptopropanoate). ### Claim 7 (depends on 1) The coating agent according to claim 1, wherein said C.sub.1 -C.sub.8 -alkyl ester of (meth)acrylic acid is a member selected from the group consisting of methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, and butyl methacrylate. ### Claim 8 (depends on 1) The coating agent according to claim 1, wherein the content of thinner in the coating agent is such that the coating agent has a viscosity within the range of about 10 to about 250 mPa.sec. ### Claim 9 (depends on 1) A polymethyl methacrylate plastic plate coated at least in part with a cured coating prepared from the coating agent of claim 1. ### Claim 10 (depends on 1) A polycarbonate plastic plate coated at least in part with a cured coating prepared from the coating agent of claim 1. ### Claim 11 (depends on 1) A method of coating plastic articles comprising: coating said plastic article with the coating agent according to claim 1.