Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Reexamination Certificate
2000-12-18
2003-08-26
Sellers, Robert E. L. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
C525S109000, C525S110000, C525S111000, C525S127000, C525S438000, C525S453000, C525S454000, C525S523000, C525S533000
Reexamination Certificate
active
06610817
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to organic reactive diluents and their use in crosslinkable coating compositions. More specifically, the invention discloses methods of preparing organic reactive diluents and crosslinkable coating compositions.
BACKGROUND OF THE INVENTION
Most coating compositions contain one or more film-forming resins and polymers and organic solvents. Even waterborne (or water-based) coating compositions usually include a portion of an organic solvent or cosolvent. The organic solvent serves a number of functions. First, particularly for solventborne (or solvent-based) compositions, the organic solvent reduces the viscosity of the coating composition to facilitate its application to a substrate. The solvent is volatile and evaporates from the coating during and after application. In addition, a portion of the solvent is generally slower to evaporate so that it remains in the applied coating to enhance film formation and flow of the coating. In waterborne coatings, for which water is the principal viscosity reducer, organic cosolvents may also be used to help stabilize the dispersed film-forming materials.
The presence of the volatile organic solvents is of concern, however, because they form the bulk of the regulated emissions produced during application and curing of the coating composition. While waterborne coating compositions offer lower emissions, waterborne coating also require more elaborate application methods and tend to produce coatings that are more water-sensitive. Another avenue for reducing regulated emissions has been to include so-called reactive diluents, low molecular weight functional compounds that reduce the viscosity of the coating composition and aid in leveling and film formation like solvents, but are reactive with the film forming resin and/or crosslinking agent so as to become a part of the film when the coating composition cures.
Birkmeyer et al., U.S. Pat. No. 4,314,918 describes coating compositions having a vehicle portion that essentially consists of: (a) from 35 to 55 wt % of a cross-linking agent; (b) from 15% to 50% of a curable polyol resin; and (c) from 15% to 50% of a reactive diluent. The reactive diluent is synthesized by reacting from 0.25 to 4 moles of a glycidyl ester with one mole of a functional material having a molecular weight of less than 1000, a hydroxy equivalent weight of from 30 to 1000, a carboxyl equivalent weight of from 50 to 1000, and a total hydroxyl and carboxyl functionality of at least 2.0. The Birkmeyer patent does not disclose methods for producing reactive diluents from polyepoxide compounds.
Henry et al., U.S. Pat. No. 6,069,203, discloses a hydroxy-functional oligoether similar to the reactive diluent of the Birkmeyer patent. The oligoether of the Henry patent is prepared by reacting a polyol free of carboxyl groups and having three or four hydroxyl groups with a mono-glycidyl ester of a branched carboxylic acid, containing from 5 to 13 carbon atoms.
Swarup et al., U.S. Pat. No. 6,087,464, Jones et al., U.S. Pat. No. 5,973,072,and Yezrielev et al., U.S. Pat. No. 5,681,906 disclose coating compositions including a phenolic ester alcohol made by reacting hydroxybenzoic acid and an epoxide-functional compound, or a phenolic ester urethane compound prepared by reacting the phenolic ester alcohol with a diisocyanate compound. These patents do not disclose aliphatic reactive diluents or methods for producing aliphatic reactive diluents. Aromatic materials such as those of the Swarup, Jones, and Yezrielev patents, however, are unsuitable for exterior automotive topcoat coatings because they tend to yellow from outdoor exposure.
It would, therefore, be desirable to prepare reactive diluent materials that could be included in automotive topcoat coatings in substantial amounts. It would also be desirable to prepare such reactive diluents by using aliphatic polyepoxide compounds.
SUMMARY OF THE INVENTION
A method of forming a reactive diluent comprises a step of reacting together
(a) a compound with a molecular weight of up to about 1000 having at least two glycidyl groups and
(b) a compound with a molecular weight of up to about 1000, having one hydroxyl or carboxyl group, or having one carboxyl group and one or more hydroxyl groups.
From about 0.95 to about 1.05 moles of compound (b) is reacted for each equivalent of glycidyl groups of the compound (a).
By molecular weight, we mean the actual molecular weight of a compound, or, if the compound is a polydisperse oligomeric or polymeric material, we mean the weight average molecular weight of the material.
The reactive diluent is included in a coating composition in an amount from about 5% to about 50% by weight, based on the total nonvolatile weight of the vehicle. The vehicle is understood as the resinous or polymeric material of the coating composition.
DETAILED DESCRIPTION OF THE INVENTION
The reactive diluent is prepared by reacting together a polyglycidyl compound having a molecular weight of up to about 1000 and a hydroxyl- and/or carboxyl-functional compound with a molecular weight of up to about 1000.
The polyglycidyl compound is preferably aliphatic, more preferably cycloaliphatic. The polyglycidyl compound preferably has from 2 to about 4 glycidyl groups, and more preferably 2 glycidyl groups. The polyglycidyl compounds are glycidyl esters, particularly diglycidyl esters. In particular, the polyglycidyl compound may be selected from hexahydrophthalic acid diglycidyl ester, succinic acid diglycidyl ester, and combinations of these.
The polyglycidyl compound preferably has a molecular weight of from about 200 to about 500, more preferably from about 300 to about 400.
The polyglycidyl compound is reacted with a compound that has an hydroxyl and/or carboxylic acid group. The hydroxyl and/or carboxylic acid group is preferably bound to an aliphatic carbon atom. Particularly preferably, the compound that has the hydroxyl and/or carboxylic acid group is aliphatic. When the compound has a carboxylic acid group, the compound may have from one to about 4 hydroxyl groups. It is possible in that case to avoid polymerization because the acid group reacts at a faster rate than the hydroxyl group or groups. Particular examples of suitable compounds that are reacted with the polyglycidyl compound include, without limitation, monoalcohols such as octanol, and cyclohexanol; monocarboxylic acids such as octanoic acid, nonanoic acid, stearic acid, and cyclohexanoic acid; and hydroxycarboxylic acids such as dimethylolpropionic acid; as well as combinations of these compounds.
The hydroxyl- and/or carboxyl-functional compound has a molecular weight of up to about 1000, preferably from about 60 to about 500, and more preferably from 100 to about 300.
The reaction is carried out with a ratio of from about 0.95 to about 1.05 moles the hydroxyl- and/or carboxyl-functional compound for each equivalent of glycidyl groups of the polyglycidyl compound. Thus, on average, only about one carboxyl or hydroxyl group of each compound reacts with a glycidyl group. A catalyst for the reaction may be employed, for example tertiary amines such as triethylamine. Reaction conditions typical for such reactions and esterification reactions may be used. The reaction may be carried out in an organic solvent medium, but preferably the reaction is carried out neat, i.e., in a reactor containing only the reactants and any catalyst used. When a solvent is used, it is generally used in an amount of from about 1 to about 15 percent by weight of the reactive diluent solution product. Typical solvents include, without limitation, esters such as ethyl acetate, butyl acetate, and propyl propionate; ketones, such a methyl ethyl ketone, methyl propyl ketone, methyl isobutyl ketone, and ethyl butyl ether; glycol ether esters, such as ethylene glycol monopropyl ether acetate and propylene glycol monomethyl ether acetate; non-oxygenated solvents, such as toluene and xylene; and combinations of these.
The reactive diluent formed preferably has a molecular weight of from about 2
Mormile Patrick J.
Plassmann William H.
Tye Anthony J.
BASF Corporation
Sabourin Anne Gerry
Sellers Robert E. L.
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