Stock material or miscellaneous articles – Composite – Of polyamidoester
Reexamination Certificate
1998-12-16
2001-03-20
Short, Patricia A. (Department: 1712)
Stock material or miscellaneous articles
Composite
Of polyamidoester
C525S155000, C525S156000, C525S162000, C525S167000, C525S177000, C525S194000, C525S313000, C525S328200, C525S328800, C525S330300, C525S454000, C525S455000, C525S456000, C525S518000, C525S131000, C428S423100, C428S482000, C428S521000, C428S522000, C428S524000
Reexamination Certificate
active
06203913
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to coating compositions for thermoplastic and thermosetting plastic materials and the coated plastic articles.
BACKGROUND OF THE INVENTION
Plastic materials such as thermoplastic olefin (TPO) and reaction injected molding urethane (RIM) have been developed which are useful in many applications, such as automobile parts and accessories, containers, household appliances and other commercial items. It is often desirable to coat articles made from such plastic materials with organic coating compositions to decorate them or to protect the plastic materials from degradation when exposed to atmospheric weathering conditions such as sunlight, moisture, heat and cold. To achieve longer lasting and more durable parts, it is necessary for the coatings to be tightly adhered to the surface of the plastic.
Plastic substrates made from a variety of thermoplastic and thermosetting plastic materials have widely varying surface properties, including surface tension, roughness and flexibility, which make it difficult to achieve adequate adhesion of the organic coatings to such materials, particularly after aging or environmental exposure of the plastic materials. It is well known that to properly adhere coatings to some plastic materials, an adhesion promoter or tie coat can be used. The application of an adhesion promoter or tie coat is normally an added step in the coating process. The adhesion promoter is usually applied in a thin layer, normally about 0.25 mils (6.35 microns (&mgr;m)). Typically, adhesion promoters used on TPO plastic surfaces contain chlorinated polyolefins, some examples of which are described in U.S. Pat. Nos. 4,997,882; 5,319,032 and 5,397,602. Additionally, flame or corona pretreatment steps can be used to facilitate adequate adhesion of organic coatings to some plastic substrates.
The use of adhesion promoters and corona pretreatments in a coating system used to coat plastic substrates adds complexity and cost to the system. The application of an adhesion promoter usually entails coating the plastic substrate with the promoter, followed by some drying or curing time which increases the time of the entire coating process and will usually necessitate additional workspace. Accordingly, coating compositions which exhibit excellent adhesion directly to plastic materials such as TPO and RIM without the use of adhesion promoters or tie coats are desirable.
Polyolefin diols have been used in coating compositions to impart adhesion to the plastic substrate without the use of adhesion promoters or tie coats. However, polyolefin diols may be incompatible with the resins and/or crosslinking agents used in some coating compositions.
SUMMARY OF THE INVENTION
The present invention provides a coating composition comprising: (a) a crosslinkable film-forming system present in an amount ranging from about 75 to about 99.9 weight percent on a basis of total resin solids of the coating composition, the crosslinkable film-forming system comprising: (i) at least one crosslinkable film-forming resin; and (ii) at least one crosslinking material selected from the group consisting of aminoplasts, polyacids, anhydrides and mixtures thereof, the at least one crosslinking material being capable of reacting with the film-forming resin to form a crosslinked film; and (b) at least one substantially saturated, predominantly hydrocarbon adhesion promoting agent having an average of more than one pendant or terminal polar group per molecule which is capable of reacting with the crosslinking material, the at least one adhesion promoting agent being present in an amount ranging from about 0.1 to about 25 weight percent on a basis of total resin solids of the coating composition.
Another aspect of the present invention is a coating composition comprising (a) a crosslinkable film-forming system present in an amount ranging from about 75 to about 99.9 weight percent on a basis of total resin solids of the coating composition, the crosslinkable film-forming system comprising: (i) at least one crosslinkable film-forming resin; and (ii) at least one isocyanate-containing crosslinking material which is capable of reacting with the film-forming resin to form a crosslinked film; and (b) at least one substantially saturated, predominantly hydrocarbon adhesion promoting agent having an average of more than one pendant or terminal polar group per molecule which is capable of reacting with the crosslinking material, the at least one adhesion promoting agent being present in an amount ranging from about 0.1 to about 25 weight percent on a basis of total resin solids of the coating composition, wherein the coating composition is essentially free of monohydroxylated diene polymers and the equivalent ratio of isocyanate-functional groups of the isocyanate-containing crosslinking material to polar groups of the film-forming resin and/or adhesion promoting agent is greater than 0.8:1.
Yet another aspect of the present invention is a coating composition comprising: (a) at least one crosslinkable film-forming resin; (b) at least one crosslinking material; (c) at least one substantially saturated, predominantly hydrocarbon adhesion promoting agent having at least one pendant or terminal polar group that is reactive with the crosslinking material; and (d) at least one compatibilizer selected from the group consisting of hydrocarbon alcohols containing at least twelve contiguous carbon atoms and resinous materials containing at least one pendent or internal hydrocarbon chain containing at least eight contiguous carbon atoms.
Another aspect of the present invention is a coating composition comprising: (a) at least one substantially saturated, predominantly hydrocarbon adhesion promoting agent having at least one pendant or terminal polar group that is reactive with a crosslinking material; and (b) at least one resinous compatibilizer having at least one pendent or internal hydrocarbon chain containing at least eight contiguous carbon atoms; and (c) at least one crosslinking material which is capable of reacting with the compatibilizer to form a crosslinked film.
The present invention also provides plastic articles coated with the above coating compositions.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Unless otherwise specified, all of the numerical ranges, amounts, values and percentages, such as those for amounts of materials, times and temperatures of reaction, ratios of amounts, values for molecular weight, whether number average molecular weight (“Mn”) or weight average molecular weight (“Mw”), and others in the following portion of the specification may be read as if prefaced by the word “about” even though the term “about” may not expressly appear with the value, amount or range. Also molecular weight quantities, whether Mn or Mw, are those determinable from gel permeation chromatography using polystyrene as standards. The term “equivalent weight” is a calculated value based on the relative amounts of the various ingredients used in making the specified material and is based on the solids of the specified material. The relative amounts are those that result in the theoretical weight in grams of the material like a polymer produced from the ingredients and give a theoretical number of the particular functional group that is present in the resulting polymer. The theoretical polymer weight is divided by the theoretical number to give the equivalent weight. For example, hydroxyl equivalent weight is based on the equivalents of reactive pendant and/or terminal hydroxyl groups in the hydroxyl-containing polymer.
The coating compositions of the present invention are suitable for use as a primer applied directly to a plastic substrate, a colored topcoat applied directly to a plastic substrate, a colored basecoat applied directly to a plastic substrate that is subsequently topcoated with a clear topcoat in a basecoat-clearcoat coated composite, or a clear topcoat applied directly to a colored plastic substrate. As used herein, the term “plastic” is intended to include any of
Kondos Constantine A.
McEntire Edward E.
Nakajima Masayuki
Nugent, Jr. Richard M.
Altman Deborah M.
Cannoni Anna Marie
PPG Industries Ohio Inc.
Short Patricia A.
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