# US 5,348,632 A · Method of plasma treating a surface of a workpiece, vacuum treatment apparatus and previously plasma treated plastic article > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,348,632 A - Document ID: US5348632A - Status: Granted - Kind: A - Application number: 07/984,531 - Filed: 1992-12-02 - Granted: 1994-09-20 - Earliest claimed: 1991-12-23 - Assignees: Balzers Aktiengesellschaft - Inventors: Stephan Jost - Web page: https://patentgrep.com/patent/US5348632A ## CPC - C08J 5/10: characterised by the additives used in the polymer mixture - B29C 59/14: by plasma treatment {(plasma tubes per se H01J)} - B29C 2037/903: {by means of a computer} - C08J 2323/02: not modified by chemical after treatment - 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) - B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00) ## Abstract In order to increase at least the adherence of lacquer on a workpiece surface consisting of at least substantially one synthetic, organic polymer, which workpiece is plasma treated in an environment of reactive gas, the treatment duration is selected at least close to an adherence maximum in a lacquer adherence-/treatment duration diagram and/or the gas pressure at least close to an adherence maximum in a lacquer adherence-/gas pressure diagram. ## Claims ### Claim 1 A method for plasma treating a surface of a workpiece during a treatment duration and in an environment of reactive gas at a gas pressure, in order to increase an adherence of a lacquer to the surface, the surface consisting essentially of at least one synthetic, organic polymer, the method comprising: selecting at least one of, the duration for the treatment, and the gas pressure for the reactive gas, such that if the duration is selected, the selected duration is within a range corresponding to a substantially flat region of an adherence maximum of a lacquer in a lacquer adherence-treatment duration diagram, and such that if the gas pressure is selected, the selected gas pressure is within a range corresponding to a substantially flat range of an adherence maximum of a lacquer in a lacquer adherence-gas pressure diagram; and plasma treating the surface of a workpiece following the at least one of the selected duration and selected gas pressure. ### Claim 2 (depends on 1) The method of claim 1 wherein the surface consist essentially of a plastic material based on polypropylene, the selected duration T being selected to be: 15 seconds.ltoreq.T.ltoreq.180 seconds. ### Claim 3 (depends on 2) The method of claim 2 wherein the selected duration is selected to be: 20 seconds.ltoreq.T.ltoreq.120 seconds. ### Claim 4 (depends on 3) The method of claim 3 wherein the selected duration is selected to be: 20 seconds.ltoreq.T.ltoreq.90 seconds. ### Claim 5 (depends on 1) The method of claim 1 wherein, the selected duration T as based on a duration T.sub.o at which the adherence maximum of a lacquer in the lacquer adherence-treatment duration diagram occurs, is selected to be: 1/3 T.sub.o .ltoreq.T.ltoreq.3 T.sub.o. ### Claim 6 (depends on 5) The method of claim 5 wherein the selected duration is selected to be: 1/2 T.sub.o .ltoreq.T.ltoreq.2 T.sub.o. ### Claim 7 (depends on 6) The method of claim 6 wherein the selected duration is selected to be: 2/3 T.sub.o .ltoreq.T.ltoreq.3/2 T.sub.o. ### Claim 8 (depends on 1) The method of claim 1 wherein the surface consists essentially of a plastic material based on polypropylene, the selected gas pressure p being selected to be: 3.3.multidot.10.sup.-3 mbar.ltoreq.p.ltoreq.40.multidot.10.sup.-3 mbar. ### Claim 9 (depends on 8) The method of claim 8 wherein the selected gas pressure is selected to be: 6.6.multidot.10.sup.-3 mbar.ltoreq.p.ltoreq.35.multidot.10.sup.-3 mbar. ### Claim 10 (depends on 9) The method of claim 9 wherein the selected gas pressure is selected to be: 9.multidot.10.sup.-3 mbar.ltoreq.p.ltoreq.20.multidot.10.sup.-3 mbar. ### Claim 11 (depends on 1) The method of claim 1 wherein, the selected gas pressure p as based on a pressure P.sub.o at which the adherence maximum of a lacquer in the lacquer adherence-gas pressure diagram occurs, is selected to be: 1/4 p.sub.o .ltoreq.p.ltoreq.3 p.sub.o. ### Claim 12 (depends on 11) The method of claim 11 wherein, the selected pressure is selected to be: 1/2 p.sub.o .ltoreq.p.ltoreq.21/2 p.sub.o. ### Claim 13 (depends on 12) The method of claim 12 wherein, the selected gas pressure is selected to be: 7/10.sub.o p.sub.o .ltoreq.p.ltoreq.11/2 p.sub.o. ### Claim 14 (depends on 1) The method of claim 1, including generating a plasma during the treatment using an electrical plasma excitation signal having at least one predominant power component in a frequency range between DC and 1 MHz, both inclusive. ### Claim 15 (depends on 1) The method of claim 1 wherein, the frequency range is between DC and 100 kHz, both inclusive. ### Claim 16 (depends on 14) The method of claim 14, wherein the frequency range is between DC and 10 kHz, both inclusive. ### Claim 17 (depends on 16) The method of claim 16, wherein the frequency is between 50 and 200 Hz, both inclusive. ### Claim 18 (depends on 14) The method of claim 14 including, generating the excitation signal by providing a standard power source having a fundamental frequency and rectifying the fundamental frequency. ### Claim 19 (depends on 1) The method of claim 1, in which said reactive gas is selected to be a N.sub.2, O.sub.2 -gas mixture. ### Claim 20 (depends on 1) The method of claim 1, in which air is selected as said reactive gas. ### Claim 21 (depends on 19) The method of claim 19, wherein the reactive gas contains N.sub.2 and O.sub.2 in a ratio of N.sub.2 /O.sub.2 of about 7:3. ### Claim 22 (depends on 1) The method of claim 1 including, generating a plasma during the treatment using a plasma generating voltage having a root mean square value between 1 and 6 kV, both inclusive. ### Claim 23 (depends on 22) The method of claim 22, wherein the root mean square value is between 2 and 5 kV, both inclusive. ### Claim 24 (depends on 1) The method of claim 1, in which said surface is a polyolefine surface. ### Claim 25 (depends on 24) The method of claim 24, in which a maximal dimension of the workpiece surface is.gtoreq.1 meter. ### Claim 26 (depends on 24) The method of claim 24 wherein, the surface consisting essentially of a plastic material mixture based on a material selected from the group consisting of polypropylene and polyethylene. ### Claim 27 (depends on 25) The method of claim 25, wherein the workpiece is a plastic material part of a motor vehicle. ### Claim 28 (depends on 27) The method of claim 27, wherein the plastic material part of a motor vehicle comprises an automobile body. ### Claim 29 (depends on 1) The method of claim 1, in which the surface of the workpiece is arranged between at least one reactive gas inlet and a pump.