Stock material or miscellaneous articles – Composite – Of epoxy ether
Reexamination Certificate
2001-04-12
2002-11-12
Dawson, Robert (Department: 1712)
Stock material or miscellaneous articles
Composite
Of epoxy ether
C156S330000, C523S404000, C523S416000, C523S417000, C523S420000, C525S533000
Reexamination Certificate
active
06479151
ABSTRACT:
This application claims priority of European Application No. 00201327.4, filed on Apr. 12, 2000.
BACKGROUND OF THE INVENTION
The present invention relates to a water borne two-component cross-linkable composition comprising an aqueous dispersion of an amino-functional polymer and a compound comprising at least two acetoacetate groups or acetoacetamide groups or a combination of the two groups.
The reaction mechanism by which cross-linking occurs is as follows:
The advantage of such a two-component composition is that curing can be achieved at low temperatures, for instance ambient temperature, or in a short time at elevated temperatures, for instance 30 to 60 minutes at 60° C.
A disadvantage of such a two-component composition is a limited pot life due to premature reactions in the composition, causing a large increase in viscosity and subsequent gelation. More particularly, the reaction between a primary amino group and an acetoacetate or acetoacetamide group is much too fast for actual use in two-component systems.
In the past comparable two-component systems have been solvent borne, based on the combination of polyacetoacetates and polyketimines (ketone blocked amines), as described in U.S. Pat. No. 3,668,183, K. L. Hoy et al.,
Journal of Paint Technology,
Vol. 46, No. 591, pp. 70-75 (1974), and C. H. Carder et al.,
Journal of Paint Technology,
Vol. 46, No. 591, p. 76-80 (1974). These systems are in fact moisture curing systems, because the velocity determining step in this reaction is the deblocking of the ketimine into an amino group and a ketone by hydrolysis.
U.S. Pat. No. 5,227,414 discloses water borne two-component coating compositions based on an aqueous dispersion of an amino-functional polyurethane and an epoxy cross-linker. A disadvantage of these systems is that curing at ambient temperature is rather slow.
Heat curable water borne coating compositions based on an amino-functional polymer dispersion are described in U.S. Pat. No. 4,096,105. These aqueous amino-functional polymer dispersions are cross-linked by unsaturated carbonyl compounds such as acryloyl-functional compounds, and are used in cathodic electrocoating applications.
SUMMARY OF THE INVENTION
The present invention provides a water borne two-component cross-linkable composition based on an aqueous dispersion of an amino-functional epoxy derived polymer and a compound comprising at least two acetoacetate groups or acetoacetamide groups or a combination of the two groups. This composition provides coatings with high gloss, good water and solvent resistance, and high hardness. This composition also provides adhesives with high adhesion strength.
DETAILED DESCRIPTION OF THE INVENTION
According to the invention, a water borne two-component cross-linkable composition is provided comprising:
A) an aqueous dispersion of an at least partially neutralized amino-functional epoxy derived polymer and
B) a compound comprising at least two acetoacetate groups or acetoacetamide groups or a combination of the two groups.
The amino-functional epoxy derived polymer may be prepared from:
a) at least one bisepoxide compound,
b) at least one amino-functional compound comprising at least one primary amine group selected from
1) an alkyl amine with 2 to 20 carbon atoms in the alkyl group,
2) a polyether amine with a Mn=500 to 3000,
3) N-alkyl amino alkyl amine, and/ or
4) N-hydroxy alkyl amino alkyl amine, and
c) at least one compound containing at least one —NH— group and at least one ketimine group.
The bisepoxide compound (a) is preferably selected from diglycidyl ethers of Bisphenol A and F or their higher molecular weight homologues, such as Epikote® resins from Shell, i.e. Epikote® 828 and Epikote® 1001, the diglycidyl ether of hydrogenated Bisphenol A, such as Eponex® 1510 from Shell, various polyethylene glycol or polypropylene glycol diglycidyl ethers, and mixtures thereof.
Examples of alkyl amines (b1) also include alkyl amines with other functional groups such as ethanol amine. Preferably, the alkyl amine has 6 to 18 carbon atoms in the alkyl group. Typical examples thereof are octyl amine, dodecyl amine, tetradecyl amine, and mixtures thereof, such as Armeen® CD from Akzo Nobel Chemicals.
Preferably, the polyether amine (b2) is selected from C
1
-C
4
alkoxy polyoxy ethylene/polyoxy propylene amine. Examples include methoxy polyoxy ethylene/polyoxy propylene amines, which are available from Texaco under the tradename Jeffamine®, such as Jeffamine® M-1000 (PO/ EO=3/19; Mn=1176) and Jeffamine® M-2070 (PO/ EO=10/32; Mn=2200).
The use of N-alkyl amino alkyl amine (b3) and N-hydroxy alkyl amino alkyl amine (b4) leads to a branched structure, because these amines have a functionality of 3 towards the bisepoxide compound. Accordingly, an epoxy functionality higher than 2 is obtained. Preferred is a functionality of 2 to 3.5. With higher functionalities there is a risk of gelation during the synthesis.
One example of N-alkyl amino alkyl amine (b3) is N-ethyl ethylene diamine.
One example of N-hydroxy alkyl amino alkyl amine (b4) is 2-(2-amino ethyl amino) ethanol.
It has been found that incorporating a non-ionic polyether group into the amino-functional epoxy derived polymer provides a better colloidal stability, smaller particle size of the aqueous dispersions, and improvement in the emulsification of compound B in the amino-functional epoxy derived polymer dispersion. Accordingly, it is preferred that the amino-functional compound (b) comprising at least one primary amine group comprises a polyether amine (b2). Certain combinations of amino-functional compounds with a polyether amine (b2) are more preferred, such as a polyether amine (b2) combined with an alkyl amine (b1) with 2 to 20 carbon atoms in the alkyl group and a polyether amine (b2) with a N-hydroxy alkyl amino alkyl amine (b4).
Compounds containing at least one —NH— group and at least one ketimine group (c) are prepared by reacting a compound bearing a primary amine and a secondary amino group with a ketone. Examples of a compound bearing a primary amine and a secondary amino group include diethylene triamine, dipropylene triamine, dihexylene triamine, triethylene tetramine, tripropylene tetramine, N-amino ethyl piperazine, N-methyl-1,3-propane diamine, 2-(2-amino ethyl amino) ethanol, and N-ethyl ethylene diamine. Suitable examples of ketones include acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, dibutyl ketone, di-isobutyl ketone, ethyl amyl ketone, and methyl hexyl ketone.
The amino-functional epoxy derived polymers are preferably prepared in a first step by chain extension of the bisepoxides by the amino-functional compound comprising at least one primary amine group. The bisepoxides are used in excess, so that an epoxy terminated prepolymer is formed. In a second step the epoxy terminated prepolymer is further reacted with the ketimine compound also containing a NH group.
Depending on the molecular weight, the ketimine-functional epoxy derived polymer can be synthesised in the melt or in an organic solvent, such as a ketone, glycol ether, propylene glycol ether or a cyclic ether. Examples include methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, butyl glycol, 1-methoxy propanol, dioxane, and tetrahydrofuran. The reaction temperature ranges from 40 to 150° C. and preferably is between 60 and 120° C.
The so formed ketimine-functional epoxy derived polymer is dispersed in water with sufficient volatile organic acid to convert the ketimine groups into primary amino groups and ketones and to form an acid salt of 10 to 100% of the amino groups, preferably 20 to 75% of the amino groups, followed by removal of the ketone and the solvent by (azeotropic) distillation, optionally under reduced pressure, preferably under vacuum. Formation of acid salt groups means that 10 to 100%, preferably 20 to 75%, of the amino groups are neutralized.
Examples of useful volatile organic acids are formic acid, acetic acid, lactic acid, and propionic acid. In combination with these volatile organic acids
Buter Roelof
Geurink Petrus Johannes Arnoldus
Schlief Josephina Johanna Hendrika Maria
Veer Tom Van't
Akzo Nobel N.V.
Aylward D.
Dawson Robert
McGillycuddy Joan M.
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