Claims
- 1. A method for making a molded synthetic resin article having a scratch resistant coating thereon, which method comprises the following steps:
- (a) heating an injection mold;
- (b) applying a polymerizable material suitable for formation of the scratch resistant coating to the forming surface of said injection mold;
- (c) partially polymerizing the polymerizable coating material;
- (d) injecting a molten thermoplastic polymeric molding composition into the mold when it is closed and while said polymerizable coating material is still only partially polymerized;
- (e) removing the molded article from the mold after the coating and the molding composition have hardened;
- said mold being heated in step (a) to a temperature range wherein the partial polymerization of step (c) proceeds rapidly, but below the temperature of the molten thermoplastic polymeric molding composition of step (d); the partial polymerization of step (c) proceeding, prior to step (d), for a time sufficient to prevent displacement of the coating material on the mold and to bond the coating material to the thermoplastic polymeric molding composition when injected, said molding composition having a temperature sufficient to cause completion of the polymerization of the coating material; said coating material being a liquid mixture of at least one monomer capable of free radical polymerization and having more than one polymerizable double bond and of at least one initiator forming free radicals at a temperature between the temperature of the injection mold and the temperature of the molten thermoplastic polymeric molding composition.
- 2. A method as in claim 1 wherein the material for formation of the scratch resistant coating is applied to the forming surface of the mold when said surface is at a temperature between 40.degree. C. and 150.degree. C.
- 3. A method as in claim 1 wherein said material contains a volatile organic solvent.
- 4. A method as in claim 3 wherein said solvent has a boiling point below the boiling point of the monomer or monomer mixture.
- 5. A method as in claim 4 wherein said solvent is free of carbon-to-carbon double bonds susceptible of free radical polymerization.
- 6. A method as in claim 3 wherein the material containing a solvent is sprayed onto the forming surface of the open injection mold and the latter is closed after the solvent has substantially volatilized, whereupon the thermoplastic molding composition is injected.
- 7. A method as in claim 1 wherein a compound having more than one acryloyl group is used as said monomer having more than one polymerizable double bond.
- 8. A method as in claim 7 wherein said material contains at least 70 mole percent of the polymerizable double bonds in acryloyl groups.
- 9. A method as in claim 7 wherein at least a portion of the acrylic compound used contains three acryloyl groups.
- 10. A method as in claim 1 wherein polymerizable monomers having a boiling point above 140.degree. C. are used.
- 11. A method as in claim 1 wherein a free radical forming initiator having a half-life of less than two minutes at 100.degree. C. is used.
- 12. A method as in claim 10 wherein said initiator is an aliphatic peroxydicarbonate.
- 13. A method as in claim 1 wherein said thermoplastic molding composition is injected into the closed injection mold at a temperature between 230.degree. C. and 350.degree. C.
- 14. A method as in claim 1 wherein the material susceptible of free radical polymerization applied to the injection mold is exposed to the action of atmospheric oxygen during its partial polymerization.
- 15. A method as in claim 1 wherein said thermoplastic molding composition is injected into the injection mold 1 to 20 seconds after said material comprising polymerizable monomers has been applied to its forming surface.
Priority Claims (1)
Number |
Date |
Country |
Kind |
3642138 |
Dec 1986 |
DEX |
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Parent Case Info
This application is a continuation of application Ser. No. 07/128,621 filed Dec. 4, 1987 and now abandoned.
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Matsuo et al. |
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Emanuel et al. |
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4776992 |
Irving et al. |
Oct 1988 |
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Continuations (1)
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Number |
Date |
Country |
Parent |
128621 |
Dec 1987 |
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