Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Reexamination Certificate
2001-01-25
2003-11-04
Hampton-Hightower, P. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
C528S354000, C528S318000, C528S323000, C528S359000, C526S266000, C525S410000, C525S411000, C525S413000, C525S415000
Reexamination Certificate
active
06642346
ABSTRACT:
FIELD OF THE INVENTION
This invention is directed to a coating composition and in particular to a clear coating composition used for original equipment manufacturing (OEM) or refinishing uses in the automotive industry, which coating composition utilizes an acrylic polymer which contains one or more substituted or unsubstituted exomethylene lactones or lactams as a comonomer.
TECHNICAL BACKGROUND OF THE INVENTION
It is well known that consumers prefer automobiles and trucks with an exterior finish having an attractive aesthetic appearance, including high gloss and excellent DOI (distinctness of image). While ever more aesthetically attractive finishes have been obtained, deterioration of the finish over time, whereby the exterior finish of an automobile or truck loses its luster or other aspects of its aesthetic appearance, may be all the more noticeable. In order to protect and preserve the aesthetic qualities of the finish on a vehicle, it is common to provide a clear (unpigmented) clear coat over a colored (pigmented) basecoat, so that the basecoat remains unaffected even on prolonged exposure to the environment or weathering.
Clear coat/color coat finishes for automobiles and trucks have been used in recent years and are very popular. Kurauchi et al. U.S. Pat. No. 4,728,543 issued Mar. 1, 1988, and Benefiel et al. U.S. Pat. No. 3,639,147 issued Feb. 1, 1972, show the application of a clear coat to a color coat or basecoat in a “wet on wet” application, i.e., the clear coat is applied before the color coat is completely cured.
Although application of the clearcoat finish is effective in reducing finish marring, it is expensive and a means to increase the mar resistance of the finish as well as reduce the cost of application would be desirable. In one instance the introduction of alkoxysilane compounds into the coating composition has been effective in increasing the finish resistance to chemical and environmental weathering (U.S. Pat. No. 5,244,696). U.S. Pat. No. 5,286,782 discloses coating compositions used as a clearcoat in an automotive finish having increased mar resistance comprising a) an acrylic polymer derived from styrene, two methacrylate polymers and a hydroxy alkyl (meth)acrylate; b) a polyol component and c) an organic polyisocyanate. The first methacrylate in a) is methyl methacrylate, isobornyl methacrylate or cyclohexyl methacrylate; the second methacrylate is n-butyl methacrylate, isobutyl methacrylate or ethyl hexyl methacrylate. JP 11279232 teaches the use of 1-(&ggr;-Butyrolacton-2-yl)ethyl (meth)acrylate copolymers in coatings to enhance coating adhesion to a metal surface.
Although the above cited compositions provide effective mar resistance, better resistance is still an issue and cost of application continues to remain a barrier. The problem to be solved therefore is to develop a coating composition having high mar and scratch resistance while reducing the cost of application. Applicants have solved the stated problem by the discovery that the introduction of a substituted or unsubstituted exomethylene lactone or lactam as a comonomer in a coatings composition imparts enhanced mar and scratch resistance to the finish. Additionally where the exomethylene lactone or lactam is substituted, either in whole or in part for other monomers in the composition, cost may be reduced.
SUMMARY OF THE INVENTION
The present invention provides a coating composition comprising:
(a) a polymer containing at least one exomethylene lactone or lactam monomer of the structure:
where X═O or N—R
7
, n=0, 1 or 2 and R
1
, R
2
, R
3
, R
4
, R
5
, R
6
, R
7
are independently selected from the group (I) consisting of H, —CH(O), —CN and halogen, and from the group (II) consisting of —C(O)OR
9
, —C(O)NR
10
R
11
, —CR
12
(O), —C(O)OC(O)R
13
, —C(O)NR
14
COR
15
, —OC(O)R
16
, —OR
17
, —NR
18
R
19
alkyl, substituted alkyl, aryl and substituted aryl; wherein when R
1
, R
2
, R
3
, R
4
, R
5
, R
6
, R
7
are selected from group (II), they may optionally form a cyclic structure with one another; R
9
, R
10
, R
11
, R
12
, R
13
, R
14
, R
15
, R
16
, R
18
and R
19
are H, alkyl, aryl, substituted alkyl or substituted aryl; R
17
is alkyl, aryl, substituted alkyl or substituted aryl; and wherein the alkyl and substituted alkyl are C
1
-C
12
; and
(b) at least one other copolymerizable monomer.
In one embodiment the invention provides that the at least one exomethylene lactone or lactam monomer is an &agr;-methylene-&ggr;-butyrolactone monomer of the structure:
wherein R
1
, R
2
, R
5
and R
6
are each independently selected from the group (I) consisting of H, —CH(O), —CN and halogen, and from the group (II) consisting of —C(O)OR
9
, —C(O)NR
10
R
11
, —CR
12
(O), —C(O)OC(O)R
13
, —C(O)NR
14
COR
15
, —OC(O)R
16
, —OR
17
, —NR
18
R
19
alkyl, substituted alkyl, aryl and substituted aryl; wherein when R
1
and R
2
are selected from group (II), R
1
and R
2
may optionally form a cyclic structure; R
9
, R
10
, R
11
, R
12
, R
13
, R
14
, R
15
, R
16
, R
18
and R
19
are H, alkyl, aryl, substituted alkyl or substituted aryl; R
17
is alkyl, aryl, substituted alkyl or substituted aryl; and wherein the alkyl and substituted alkyl are C
1
-C
12
, and that the copolymerizable monomer of step (b) is a methacrylate monomer.
The invention additionally provides an acrylic polymer comprising:
(a) substituted or unsubstituted exomethylene lactone or lactam monomer;
(b) a first methacrylate monomer;
(c) a second methacrylate monomer; and
(d) a hydroxy alkyl methacrylate or acrylate monomer having 1-4 carbon atoms in the alkyl group.
Optionally the acrylic polymer may comprise polymerized monomers of styrene.
The invention further provides a coating composition having a film forming binder solids content of about 30-70% by weight and an organic liquid carrier, wherein the binder contains about:
(a) 50-80% by weight, based on the weight of the binder, of an acrylic polymer comprising:
(i) at least one exomethylene lactone or lactam monomer of the structure:
where X═O or N—R
7
, n=0, 1 or 2 and R
1
, R
2
, R
3
, R
4
, R
5
, R
6
, R
7
are independently selected from the group (I) consisting of H, —CH(O), —CN and halogen, and from the group (II) consisting of —C(O)OR
9
, —C(O)NR
10
OR
11
, —CR
12
(O), —C(O)OC(O)R
13
, —C(O)NR
14
COR
15
, —OC(O)R
16
, —OR
17
, —NR
18
R
19
alkyl, substituted alkyl, aryl and substituted aryl; wherein when R
1
, R
2
, R
3
, R
4
, R
5
, R
6
, R
7
are selected from group (II), they may optionally form a cyclic structure with one another; R
9
, R
10
, R
11
, R
12
, R
13
, R
14
, R
15
, R
16
, R
18
and R
19
are H, alkyl, aryl, substituted alkyl or substituted aryl; R
17
is alkyl, aryl, substituted alkyl or substituted aryl; and wherein the alkyl and substituted alkyl are C
1
-C
12
;
(ii) at least one methacrylate monomer selected from the group consisting of methyl methacrylate, isobornyl methacrylate, cyclohexyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, ethyl hexyl methacrylate and mixtures thereof; and
(iii) at least one hydroxy alkylmethacrylate or acrylate monomer each having 1-4 carbon atoms in the alkyl group wherein the polymer has a number average molecular weight of about 1,000-100,000 determined by gel permeation chromotography; and
(b) 1-20% by weight, based on the weight of the binder, of a polyol component; and
(c) 10-49% by weight, based on the weight of the binder, of a crosslinking agent selected from the group consisting of an organic polyisocyanate, a melamine formaldehyde resin, and a silane or mixtures thereof.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides coating compositions containing acrylic polymers having at least one exomethylene lactone or lactam monomer for, eample an &agr;-methylene-&ggr;-butyrolactone monomer. The inclusion of the lactone, lactam or &agr;-methylene-&ggr;-butyrolactone monomer results in increased hardness of the coating; improved the scratch resistance; improved mar resistance; and, potentially, increased cure rate, and improved weatherability of the c
Brandenburg Charles J.
King Randal D.
Oien Larry G.
Uhlianuk Peter W.
Benjamin Steven C.
E. I. du Pont de Nemours and Company
Hampton-Hightower P.
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