Monomeric aminoplast crosslinking agents
AssigneeAmerican Cyanamid Company
InventorsJeno G. Szita, Robert G. Lees
Life of this patent
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Abstract
A monomeric alkoxymethylated aminoplast crosslinking agent derived from a m-TMI/melamine 1:1 adduct and a process for its preparation is provided. The process comprises contacting melamine with M-TMI, contacting the adduct formed with formaldehyde, and contacting the hydroxymethylated adduct with an alcohol such as butanol. A curable composition comprising the monomeric aminoplast crosslinker and a polyfunctional active hydrogen-containing material is also provided. An improved method of coating using the curable composition to produce cured films or objects is also provided.
Claims36
A composition of matter represented by the formula:
- ##STR7## wherein the point of attachment of the isopropenyl group is meta-, para-, or a mixture thereof, and wherein each of R.sup.1, R.sup.2 , R.sup.3, and R.sup.4 is independently selected from the group consisting of hydrogen, hydroxymethyl, an alkoxymethyl, an aminoplast-containing group derived from condensation thereof, and mixtures of any of the preceding moieties.
A process for preparing an alkoxymethylated aminoplast comprising:
- (a) contacting melamine with isopropenyl-alpha, alpha-dimethylbenzyl isocyanate in a solvent having a high dielectric constant at a temperature and for a length of time sufficient to produce a 1:1 adduct,
- (b) contacting the adduct of step (a) with 2 to moles of formaldehyde per mole of adduct to produce a hydroxymethylated adduct, and
- (c) contacting said hydroxymethylated adduct of step (b) with 2 to 30 moles of an alcohol per mole of hydroxymethylated adduct at an acidic pH to produce an alkoxymethylated aminoplast.
A curable composition comprising:
- (i) an aminoplast crosslinking agent represented by the formula:
- ##STR12## wherein the point of attachment of the isopropenyl group is meta-, para-, or a mixture thereof, and wherein each of R.sup.1, R.sup.2, R.sup.3, and R.sup.4 is independently selected from the group consisting of hydrogen, hydroxymethyl, an alkoxymethyl of 1 to 6 carbon atoms, an aminoplast-containing group derived from condensation thereof and mixtures of any of the preceding moieties, with the proviso that at least one of R.sup.1, R.sup.2, R.sup.3, and R.sup.4 are independently selected from the group consisting of hydroxymethyl, an alkoxymethyl of 1 to 6 carbon atoms, and mixtures thereof, and
- (ii) a polyfunctional active hydrogen-containing material.
The curable composition of claim 25 further comprising, from about 0.01 to about 5.0 weight percent, a cure catalyst.
An improved method for coating of the type having the steps of (I) contacting a substrate with a curable composition containing a crosslinking agent and a polyfunctional active hydrogen-containing material, and (II) thereafter curing, wherein the improvement comprises:
- (A) contacting said substrate with a curable composition comprising:
- (i) an aminoplast crosslinking agent represented by the formula:
- ##STR15## wherein the point of attachment of the isopropenyl group is meta-, para-, or a mixture thereof, and wherein each of R.sup.1, R.sup.2, R.sup.3, and R.sup.4 is independently selected from the group consisting of hydrogen, hydroxymethyl, an alkoxymethyl of 1 to 6 carbon atoms, an aminoplast-containing group derived from condensation thereof, and mixtures of any of the preceding, with the proviso that at least one of R.sup.1, R.sup.2, R.sup.3, and R.sup.4 are independently selected from the group consisting of hydroxymethyl, an alkoxymethyl of 1 to 6 carbon atoms, and mixtures thereof, and
- (ii) a polyfunctional active hydrogen-containing material;
- and
- (B) thereafter heat curing said curable composition.
Dependencies are inferred from the claim text.