Low-temperature curable compositions
This invention pertains to a curable composition comprising a first component having β-ketoester and/or malonate functionalities and a second component having two or more aldehyde functionalities. The compositions can be cured at room temperature or low temperatures to yield crosslinked networks that are capable of providing desirable properties for coating and adhesive applications. The reactive functionalities of β-ketoester, malonate, and aldehyde can be either on polymers as the main binders or on small molecules as the crosslinkers. The curable compositions desirably are either solventless or organic solvent based.
1. A curable adhesive composition comprising:
I. a first component comprising one or more of:
a. a polyester having two or more malonate groups or
b. an adduct having two or more β-ketoester functional groups, wherein the adduct comprises one or more of: 2,2,4,4-tetramethylcyclobutane-1,3-diol diacetoacetate, glycerol triacetoacetate, tri methylolpropane triacetoacetate, or pentaerythritol tetraacetoacetate;
II. a second component selected from the group consisting of 1,3-cyclohexanedicarboxaldehyde; 1,4-cyclohexanedicarboxaldehyde; mixtures of 1,3-cyclohexanedicarboxaldehyde and 1,4-cyclohexanedicarboxaldehyde; 2,6-norbornanedicarboxaldehyde; 2,5-norbornanedicarboxaldehyde; cyclododecane-1,4,8-tricarbaldehyde; 3-(4-formylcyclohexyl)propanal; tricyclodecane dialdehyde; o-phthalaldehyde; terephthalaldehyde; isophthalaldehyde; cyclopentane-1,3-dicarbaldehyde; cyclopenta-3,5-diene-1,3-dicarbaldehyde; glutaraldehyde; benzenedipropanal; or any isomers thereof, or mixtures thereof; and
III. at least one basic catalyst.
2. The composition of claim 1 wherein the equivalent ratio of the β-ketoester and/or malonate functionalities in the first component and the aldehyde functionality in the second component is from about 1.2 to about 0.9.
3. The composition of claim 1 wherein the first component comprises at least one amorphous or semi-crystalline polyester.
4. The composition of claim 3 , wherein said amorphous or semi-crystalline polyester is an acetoacetate functional polyester comprising the residues of
a. a hydroxyl component comprising:
i. a diol in an amount ranging from 50 to 100 mole %, based on the total moles of (i) and (ii); and
ii. a polyol in an amount ranging from 0 to 50 mole %, based on the total moles of (i) and (ii);
b. a carboxyl component comprising a polycarboxylic acid compound, a derivative of polycarboxylic acid compound, or a combination thereof; and
c. an alkyl acetoacetate, a diketene, or a combination thereof in an amount ranging from about 5 to about 50 weight %, based on the total weight of (a), (b), and (c).
5. The composition of claim 3 , wherein said amorphous or semi-crystalline polyester comprises the residues of:
a. a hydroxyl component comprising:
i. a diol in an amount ranging from 50 to 100 mole %, based on the total moles of (i) and (ii); and
ii. a polyol in an amount ranging from 0 to 50 mole %, based on the total moles of (i) and (ii); and
b. malonic acid, its ester, or a combination thereof; and
c. optionally a carboxyl component, other than malonic acid or its ester, comprising a polycarboxylic acid compound, a derivative of polycarboxylic acid compound, or a combination thereof.
6. The composition of claim 5 , wherein malonic acid (b) is in an amount of about 20 to 50 mole % based on the total moles of (b) and (c).
7. The composition of claim 1 , wherein the basic catalyst is in an amount ranging from 0.5 to 5 weight % based on the total weight of (I) and (II).