Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2000-04-07
2002-07-09
Short, Patricia A. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S437000, C525S438000, C525S443000, C528S288000, C528S297000, C204S499000, C204S504000, C204S505000
Reexamination Certificate
active
06417292
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to electrodepositable coating compositions and, more particularly, to electrodepositable coating compositions providing improved film flexibility and improved humidity and chip resistance.
BACKGROUND OF THE INVENTION
Electrodepositable coatings have become the coatings of choice for corrosion protection for metal substrates, such as those used in the automobile industry. Electrodeposition processes provide higher paint utilization, outstanding corrosion protection, low environmental contamination, and a highly automated process compared to conventional non-electrophoretic coating methods.
The electrodeposition process involves immersing an electroconductive substrate into a bath of an aqueous electrocoating composition, the substrate serving as a charged electrode in an electrical circuit comprising the electrode and an oppositely charged counter-electrode. Sufficient electrical current is applied between the electrodes to deposit a substantially continuous, adherent film of the electrocoating composition onto the surface of the electroconductive substrate.
U.S. Pat. Nos. 4,148,772 and 4,104,147 disclose electrocoating compositions including polyepoxides chain extended with polyester polyols. Reaction occurs by the alcoholic primary hydroxyl of the polyester polyol opening the epoxide ring forming an ether linkage and a secondary hydroxyl group (U.S. Pat. No. 4,148,772 at column 3, lines 33-35). The chain extended polyepoxides are reacted with a secondary amine and made dispersible in water with acid.
U.S. Pat. No. 4,536,558 discloses electrodepositable resins which are prepared by reacting polyepoxides with polycarboxylic acids to produce chain extended polyepoxides. The chain extended polyepoxides are then reacted with secondary amines or, optionally, with blends of secondary amines with minor amounts of primary amines, care being taken to avoid gelation.
An object of the present invention is to provide a composition and process for the production of coatings with improved chip and blister resistance and humidity resistance while additionally providing efficiencies in application and processing, such as higher paint utilization, low environmental contamination, and a highly automated process.
SUMMARY OF THE INVENTION
The present invention provides a curable coating composition which comprises a curing agent and a substantially ungelled reaction product prepared from reactants comprising: (a) an epoxy functional polyester; and (b) a polyoxyalkylene polyamine.
Another aspect of the present invention is a curable coating composition comprising a substantially ungelled ionic reaction product prepared from reactants comprising: (a) an epoxy functional polyester prepared from reactants comprising: (1) the reaction product of a polyol and a polycarboxylic acid or anhydrides thereof; and (2) an epoxy functional material; and (b) an amine-functional material.
A curable coating composition is provided which comprises a substantially ungelled ionic reaction product prepared from reactants comprising an epoxy functional polyester and a primary amine, wherein the reactants are essentially free of secondary amines.
A coated substrate of the invention has on at least a portion of a surface thereof a coating deposited from a coating composition which comprises: (A) a curable, substantially ungelled reaction product prepared from reactants comprising (i) an epoxy functional polyester; and (ii) a polyoxyalkylene polyamine; and (B) a curing agent.
Another coated substrate of the present invention has on at least a portion of a surface thereof a coating deposited from a coating composition which comprises: (A) a substantially ungelled ionic reaction product prepared from reactants comprising: (i) an epoxy functional polyester prepared from reactants comprising: (1) the reaction product of a polyol and a polycarboxylic acid or anhydrides thereof; and (2) an epoxy functional material; and (ii) an amine-functional material; and (B) a curing agent.
Another aspect of the present invention is a coated substrate having on at least a portion of a surface thereof a coating deposited from a coating composition which comprises a substantially ungelled ionic reaction product prepared from reactants comprising an epoxy functional polyester and a primary amine, wherein the reactants are essentially free of secondary amines.
A method of electrocoating an electrically conductive surface of the present invention comprises passing electric current between an anode and a cathode to cause an electrodepositable coating composition to deposit upon the electrically conductive surface, wherein the coating composition comprises a substantially ungelled reaction product prepared from reactants comprising: (i) an epoxy functional polyester; and (ii) a polyoxyalkylene polyamine.
Another method of electrocoating an electrically conductive surface according to the present invention comprises passing electric current between an anode and a cathode to cause an electrodepositable coating composition to deposit upon the electrically conductive surface, wherein the coating composition comprises a substantially ungelled reaction product prepared from reactants comprising: (i) an epoxy functional polyester prepared from reactants comprising (1) the reaction product of a polyol and a polycarboxylic acid or anhydrides thereof, and (2) an epoxy functional material; and (ii) an amine-functional material.
Yet another method of electrocoating an electrically conductive surface according to the present invention comprises passing electric current between an anode and a cathode to cause an electrodepositable coating composition to deposit upon the electrically conductive surface, wherein the coating composition comprises a substantially ungelled reaction product prepared from reactants comprising an epoxy functional polyester and a primary amine, and wherein the reactants are essentially free of secondary amines.
Yet another method of electrocoating an electrically conductive surface according to the present invention comprises passing electric current between an anode and a cathode, and sequentially depositing first and second electrodepositable coating compositions to form a first coating and a second coating on the electrically conductive surface, wherein the first coating composition comprises an electrically conductive material, and wherein the second coating composition comprises a substantially ungelled reaction product prepared from reactants comprising: (i) an epoxy functional polyester; and (ii)a polyoxyalkylene polyamine.
A still further method of coating a substrate comprises providing a substrate and applying a coating composition upon at least a portion of the substrate, the coating composition comprising a substantially ungelled reaction product prepared from reactants comprising an epoxy functional polyester and a polyoxyalkylene polyamine.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Other than in the operating examples, or where otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about”. Also, as used herein, the term “polymer” is meant to refer to oligomers and both homopolymers and copolymers. Additionally, any numeric reference to amounts, unless otherwise specified, are “by weight”; for instance, the phrase “solids of 34%” means “solids of 34% by weight”.
The curable coating compositions of the invention comprise one or more substantially ungelled reaction products or additives. The substantially ungelled, e.g, ionic, reaction products of the invention are prepared by reacting one or more epoxy functional polyesters with one or more amine functional materials. The reaction products may be used alone or in combination with another resin and/or other additives to provide curable electrodepositable coating compositions of the present invention. In the following discussion, the coating compositions of the
Eswarakrishnan Venkatachalam
Moriarity Thomas C.
Ritter Keith S.
Altman Deborah M.
PPG Industries Ohio Inc.
Short Patricia A.
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