Compositions and methods for improving adhesion to plastic substrates
AssigneeLord Corporation
InventorTerrance H. Dawdy
Life of this patent
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Abstract
Adhesion between an adhesive of the class of polymerizable liquid ethylenically unsaturated compounds containing a single vinyl group and solid polyester-containing plastic materials is improved by treating the substrate with a primer composition comprising an aromatic polyisocyanate and an amino resin and moisture-curing the polyisocyanate compound prior to application of the adhesive. The adhesive-joined assemblies are cured in a first stage at room temperature and, in a second stage, are post-baked at 100.degree. to 150.degree. C. to complete cure of the adhesive and the primer.
Claims10
A method for bonding polyester-based plastic materials comprising:
- (a) treating said polyester-based plastic material with a primer composition comprising at least one aromatic polyisocyanate compound, at least one amino resin and at least one acidic urethanation catalyst;
- (b) exposing such treated polyester-based plastic material to ambient conditions of temperature and humidity for a time sufficient to at least partially moisture-cure said aromatic polyisocyanate compound to form a urethane compound having sufficient --NH-- groups for subsequent reaction with functional groups of said amino resin;
- (c) applying to such treated polyester-based plastic material a room temperature-curable adhesive composition comprising ethylenically unsaturated compound having a single vinyl group;
- (d) contacting such adhesive-coated treated polyester-based plastic material with a second polyester-based plastic material, said second plastic material having been treated with said primer composition;
- (e) exposing the resulting assembly at room temperature for a time to at least initiate curing of said adhesive;
- and
- (f) baking the assembly at a temperature in the range from 100.degree. to 150.degree. C. to react functional groups of said amino resin with said --NH-- groups of said urethane compound and complete cure of said primer composition.
A method of improving adhesion between, (1), an adhesive of the class of polymerizable liquid ethylenically unsaturated compounds containing a single vinyl group and, (2), a solid polyester-containing plastic material comprising treating such plastic material with a primer composition comprising:
- (a) at least one polyisocyanate compound having the formula:
- ##STR2## wherein R.sup.1 is a divalent organic radical;
- m is 1 or 2;
- n is a digit having an average value in the range from zero to 15;
- and X is selected from the group consisting of hydrogen, alkyl radicals having from 1 to 8 carbon atoms and alkoxy radicals having from 1 to 8 carbon atoms;
- (b) at least one amino resin selected from the group consisting of melamine-formaldehyde and urea-formaldehyde condensation products;
- (c) at least one acidic material which is effective to catalyze moisture curing of isocyanate-functional materials;
- and
- (d) inert solvent.
Dependencies are inferred from the claim text.