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
2003-02-04
2004-08-31
Lipman, Bernard (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S107000, C525S123000, C525S208000
Reexamination Certificate
active
06784247
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to thermosetting compositions that contain copolymers of vinyl monomers. More specifically, the present invention is directed to a co-reactable solid particulate mixture thermosetting composition that includes functional copolymers containing isobutylene type monomers.
2. Description of Related Art
Reducing the environmental impact of coating compositions, in particular that associated with emissions into the air of volatile organics during their use, has been an area of ongoing investigation and development in recent years. Accordingly, interest in powder coatings has been increasing due, in part, to their inherently low volatile organic content (VOC), which significantly reduces air emissions during the application process. While both thermoplastic and thermoset coating compositions are commercially available, thermoset coatings are typically more desirable because of their superior physical properties, e.g., hardness and solvent resistance.
Low VOC coatings are particularly desirable in the automotive original equipment manufacture (OEM) market due to the relatively large volume of coatings that are used. However, in addition to the requirement of low VOC levels, automotive manufacturers have very strict performance requirements of the coatings that are used. For example, automotive OEM clear top coats are typically required to have a combination of good exterior durability, acid etch and water spot resistance, and excellent gloss and appearance. While liquid top coats containing, for example, capped polyisocyanate and polyol components, can provide such properties, they have the undesirable drawback of higher VOC levels relative to powder coatings that have essentially zero VOC levels.
Coating compositions containing polyol and capped polyisocyanate components (“isocyanate cured coatings”) are known and have been developed for use in a number of applications, such as industrial and automotive OEM topcoats. Such isocyanate cured coating compositions are described in, for example, U.S. Pat. Nos. 4,997,900, 5,439,896, 5,508,337, 5,554,692, and 5,777,061. However, their use has been limited due to deficiencies in, for example, flow, appearance, and storage stability. Isocyanate cured coating compositions typically include a crosslinker having two or more capped isocyanate groups, e.g., a trimer of 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane capped with e-caprolactam, and a hydroxy functional polymer, e.g., an acrylic copolymer prepared in part from a hydroxyalkyl acrylate and/or methacrylate.
Solid particulate coating formulations referred to in the industry as “powder coatings” are finding increasing use in painting metal substrates, both as primer coatings and as top or clear coats of the base coat and clear coat composite coatings. The automotive industry provides corrosion protection and decorative appearance for motor vehicles by multilayered paint composites on the various types of surfaces of motor vehicles. The finishing layers of this composite usually include the popular base coat clear coat composites. The base coat is a pigmented layer and the clear coat is a nonpigmented or only slightly pigmented layer that is applied separately to the base coat and cured to some degree with the base coat. To provide improved coating composites for motor vehicles, the industry is seeking solutions to the problem of blemishes, smudges, and coating imperfections that occur due to the action of acid rain and road dirt, and debris that may strike areas of the vehicle. These strikes can result in unaesthetic marring of the clear coat. Mar resistance is the property of a coating film which enables the film to remain unimpaired by light abrasion, impact, or pressure.
It would be desirable to develop thermosetting “powder coating” compositions that include functional copolymers that provide excellent acid resistance and mar resistance and have low VOC levels.
SUMMARY OF THE INVENTION
The present invention is directed to a thermosetting composition that includes a co-reactable solid, particulate mixture of:
(a) a film forming material comprising functional groups; and
(b) a crosslinking agent having at least two functional groups that are reactive with the functional groups in the film forming material (a) comprising a copolymer composition comprising at least 30 mol % of residues having the following alternating structural units:
—[DM—AM]—
where DM represents a residue from a donor monomer having the following structure (I):
where R
1
is linear or branched C
1
to C
4
alkyl, R
2
is selected from the group consisting of methyl, linear, cyclic, or branched C
1
to C
20
alkyl, alkenyl, aryl, alkaryl, and aralkyl; and AM represents a residue from one or more acrylic acceptor monomers.
The present invention is also directed to a method of coating a substrate, including applying the above-described thermosetting composition to the substrate, coalescing the thermosetting composition to form a substantially continuous film, and curing the thermosetting composition. The present invention is additionally directed to substrates coated using the method.
The present invention is further directed to a multi-component composite coating composition that includes a base coat deposited from a pigmented film-forming composition, and a transparent top coat applied over the base coat, where either the base coat, the transparent top coat, or both, are deposited from the above-described thermosetting composition. The present invention is additionally directed to substrates coated by the multi-component composite coating composition.
DETAILED DESCRIPTION OF THE INVENTION
Other than in the operating examples, or where otherwise indicated, all numbers or expressions referring to quantities of ingredients, reaction conditions, etc. used in the specification and claims are to be understood as modified in all instances by the term “about.” Various numerical ranges are disclosed in this patent application. Because these ranges are continuous, they include every value between the minimum and maximum values. Unless expressly indicated otherwise, the various numerical ranges specified in this application are approximations.
As used herein and in the claims, the terms “(meth)acrylate,” “(meth)acrylic,” and similar terms are meant to indicate the inclusion of the analogous acrylic and methacrylic and/or acrylate and methacrylate based molecules.
As used herein, the term “copolymer composition” is meant to include a synthesized copolymer, as well as residues from initiators, catalysts, and other elements attendant to the synthesis of the copolymer, but not covalently incorporated thereto. Such residues and other elements considered as part of the copolymer composition are typically mixed or co-mingled with the copolymer such that they tend to remain with the copolymer when it is transferred between vessels or between solvent or dispersion media.
As used herein, the term “substantially free” is meant to indicate that a material is present as an incidental impurity. In other words, the material is not intentionally added to an indicated composition, but may be present at minor or inconsequential levels because it was carried over as an impurity as part of an intended composition component.
The terms “donor monomer” and “acceptor monomer” are used throughout this application. With regard to the present invention, the term “donor monomer” refers to monomers that have a polymerizable, ethylenically unsaturated group that has relatively high electron density in the ethylenic double bond, and the term “acceptor monomer” refers to monomers that have a polymerizable, ethylenically unsaturated group that has relatively low electron density in the ethylenic double bond. This concept has been quantified to an extent by the Alfrey-Price Q-e scheme (Robert Z. Greenley, Polymer Handbook, Fourth Edition, Brandrup, Immergut and Gulke, editors, Wiley & Sons, New York, N.Y., pp. 309-319 (1999)). All e value
Barkac Karen A.
Bowser Linda J.
Coca Simion
O'Dwyer James B.
Rechenberg Karen S.
Lipman Bernard
PPG Industries Ohio Inc.
Uhl William J.
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