RADIATION-CURABLE, MOLDABLE MATERIAL, METHODS FOR CURING IT AND MOLDED ARTICLES OBTAINED THEREFROM

Title:

RADIATION-CURABLE, MOLDABLE MATERIAL, METHODS FOR CURING IT AND MOLDED ARTICLES OBTAINED THEREFROM

Document Type and Number:

WIPO Patent Application WO1996040479

Kind Code:

A1

Abstract:

The disclosed method for making hollow shells (e.g. housing for in-ear hearing aids) employs a radiation-curable polymer comprising (a) a major amount of urethane methacrylate monomer (molecular weight 360-950) having a viscosity less than about 15,000 cps at 25 DEG C, (b) a viscosity-adjusting minor amount of unreacted hydroxyalkyl-methacrylate monomer, (c) a photoinitiating amount of a photoinitiator of the formula Ar<1>-CO-C(OR)2-R', where Ar<1> is aryl (e.g. phenyl), R is C1-C4-alkyl (e.g. methyl), and R' is hydrogen or alkyl or, preferably, aryl, and, optionally, (d) a coloring agent, e.g. a pigment concentrate. Viscosity control is of major importance; so the curable composition is generally solvent-free and free of viscosity-modifying solids (other than coloring agents). Acrylates (as distinct from methacrylates) are also omitted. The fully-formulated, curable composition is easily pourable and has a viscosity of less than about 2,000 cps. The hollow shells are made by: A. pouring the curable composition into the mold cavity of a translucent mold, B. exposing all but the top surface of the mold to 200-450 nm light (e.g. UV light of 200 to 350 nm), until a solid layer < 3 mm in thickness has formed, and C. pouring out the uncured material. The thin, solid layer is then preferably subjected to a second radiation cure until the layer is toughened by cross-linking.

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Inventors:

COWPERTHWAITE GEORGE F
SHAW GARY R
SHEARISS SUSAN C

Application Number:

PCT/US1996/009873

Publication Date:

December 19, 1996

Filing Date:

June 07, 1996

Export Citation:

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Assignee:

ESSCHEM INC (US)

International Classes:

B29C35/08; B29C39/00; B29C41/18; C08F2/50; C08F290/06; H04R25/00; (IPC1-7): B29C39/00; B29C41/18; B29K75/00; B29D22/00; B65D85/88; B23B27/16

Foreign References:

US4814119A	1989-03-21
US4614787A	1986-09-30
US4929403A	1990-05-29
US5275372A	1994-01-04

Other References: