Method for producing articles by deformation substrates having a radiation cured substrate

• US 4,424,100 A
• Filed: 10/24/1980
• Issued: 01/03/1984
• Est. Priority Date: 05/04/1979
• Status: Expired due to Term

• Current Assignee: Valspar Corporation (Sherwin-Williams Company)
• Original Assignee: Mobil Oil Corporation (Exxon Mobil Corporation)
• Inventors: McCarty, William H., Nagy, Frank A., Guarino, John P.
• Primary Examiner(s): BRIGGS SR, WILBERT
• Application Number:
  US06/200,117
• Time in Patent Office: 1,166 Days
• Field of Search: 427/44, 427/54.1, 204/159.15, 204/159.16, 204/159.22, 204/159.23, 72/46
• US Class Current: 427/495
• CPC Class Codes: C08F 283/10 on to polymers containing more than one epoxy radical per molecule C08F283/004 takes precedence

Abstract

Coating compositions comprising a combination of a minor amount of high MW resin of low functionality with a large proportion of monoethylenically unsaturated monomer having a relatively high Tg to provide a coating which, when cured, will possess a degree of hardness and flexibility enabling it to withstand severe fabrication and/or flexure stresses without film failure or loss of adhesion to the substrate. By controlling the molar ratio of unsaturated carbon bonds present in polyunsaturated molecules to those present in monounsaturated molecules, one is able to predict and control the physical performance and character of the cured coating.

Claims

1. A method for preparing a radiation cured coating on a metal substrate which is subsequently fabricated with deformation, which comprises:

(a) applying to a deformable metal substrate a coating composition comprising a blend of monounsaturated and polyunsaturated molecules, and an internal lubricant such that the molar ratio of reactive unsaturated bonds present in said polyunsaturated molecules to reactive unsaturated bonds present in said monounsaturated molecules is below about 0.5; and

said internal lubricant is present in an amount sufficient to allow release of the coated metal substrate upon fabrication with deformation;

(b) exposing said blend of polymerization-inducing radiation, in the presence of a substantially oxygen-free atmosphere, for a sufficient time to effect a cure of at least 85% by weight of the monomeric unsaturated molecules in the coating having a glass transition temperature in its cured state of between about -10°

C. and +100°

C.; and

(c) subjecting the coated metal substrate to fabrication by deformation.

2. The method of claim 1 in which said unsaturated compounds are ethylenically unsaturated.

3. The method of claim 1 in which said molar ratio of unsaturated linkages is below 0.2.

4. The method of claim 1 in which said glass transition temperature of the cured composition is between about +15°

C. and +100°

C.

5. The method of claim 1 in which said molar ratio of unsaturated linkages is below 0.2 and said glass transition temperature is between about +15°

C. and +100°

C.

6. The method of claim 1 in which said composition includes a photosensitizer rendering the composition curable with ultraviolet light.

7. The method of claim 6 in which said composition additionally includes at least one other photosensitizer, said other photosensitizer exhibiting UV absorption maxima in different regions of the ultraviolet spetrum from the first photosensitizer, and at least one of said photosensitizers being strongly absorptive of UV light in the region of 2,000 to 3,000 Angstrom units.

8. The method of claim 1 in which said composition includes a pigmenting agent.

9. The method of claim 1 in which said coating is heated at a temperature of from 93°

C. to 260°

C. for a period of from 10 seconds to 10 minutes subsequent to said radiation curing step.

10. The method of claim 1 in which said coating is heated at a temperature of from 121°

C. to 204°

C. for a period of from 30 seconds to 10 minutes.

11. The method of claim 1 in which said coating composition comprises:

(a) from 0 wt.% to about 85 wt.%, relative to the mixture of (a) and (b), of a resin having approximately two unsaturated sites per molecule and a molecular weight within the approximate range of 600 to 3500;

(b) from about 18 wt.% to about 100 wt.%, relative to the mixture of (a) and (b), of an ethylenically unsaturated monomer;

(c) the relative proportions of (a) and (b) being such as would result in a ρ

-value of below about 0.5 and a coating which, when applied to a substrate and suitably cured, will have a Tg within the approximate range of +15°

C. to +100°

C.

12. The method of claim 11 in which said coating composition additionally comprises from about 0.5% to about 7% by weight of a photosensitizer rendering said composition curable by ultraviolet light.

13. The method of claim 12 in which said photosensitizer comprises a blend of two or more photoinitiators which exhibit absorption maxima in different regions of the ultraviolet spectrum.

14. The method of claim 11 in which said coating composition comprises from 8% to 70% by weight of a resin which is a reaction product of a diglycidyl ether of bisphenol-A with approximately 1 equivalent or acrylic acid per equivalent of epoxy in said ether and from 0 to 0.25 equivalents of maleic anhydride per equivalent of epoxy;

from 0 to 10% by weight of trimethylolpropane triacrylate;

from about 30% to about 92% of monoethylenically unsaturated monomer comprising butylcarbamylethyl acrylate in admixture with from 0 to 50% of another monomer chosen from the group consisting of vinylpyrollidone and an isobornyl acrylate.