Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From silicon reactant having at least one...
Reexamination Certificate
1999-12-27
2001-11-13
Thibodeau, Paul (Department: 1773)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From silicon reactant having at least one...
C528S034000, C525S100000, C525S105000, C525S106000, C428S447000, C428S413000
Reexamination Certificate
active
06316572
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a curable composition for coatings, which is preferably applied to, for example, automobiles, industrial equipment, steel furniture, building interior and exterior, electric appliances, various plastics products and the like, and to a coated article obtained from said curable composition for coatings. More particularly, it relates to a curable composition for coatings which can provide good acid resistance, scuff or scratch resistance, stain resistance, appearance and heat curability, among others, very good weather resistance and are particularly suited for top coat compositions for automobiles, to a coated article obtained from said curable composition for coatings and to a resin composition for coatings.
BACKGROUND ART
So far, coating compositions mainly comprising a melamine resin, such as an alkyd melamine resin or acrylic melamine resin, have been used in coating automobiles, industrial equipment, steel furniture, building interior and exterior, electric appliances, various plastics products and the like.
However, such coating compositions mainly comprising a melamine resin have some problems: a harmful formalin is generated in the step of curing and, since cured coatings are poor in acid resistance, they are affected by acid rain. In particular, the acid rain problem has been aggravated owing to recent air pollution and phenomena such as etching, whitening and staining or spotting of coatings or paint films have been encountered.
To solve the above problems, melamine resin-free coating compositions have already been proposed (e.g. JP Kokai H03-287650 and JP Kokai H02-45577). In such coating compositions, ester bonds resulting from the reaction of acid groups and epoxy groups serve as crosslinking sites and, therefore, said coating compositions are advantageous, as compared with the coating compositions mainly comprising a melamine resin, in that they can form coatings having good acid resistance. However, it has now been found that once the coatings which were formed from said coating compositions by reacting an acid group with an epoxy group is stained, the stains tend to be difficult to remove, although said compositions give coatings having good acid resistance. In particular, the tendency is more remarkable with tint or weak color coatings. Thus, from the viewpoint of good appearance, easy cleaning, reduced number of cleanings, or the like, improvements in stain resistance are desired.
Furthermore, in top coat finishing of automobiles, improvements in finish appearance are earnestly desired.
When it is demanded that coated articles have high quality appearance, it is a usual practice to further incorporate a leveling agent, which is an appearance modifier, in top coat paints. At present, without addition of a leveling agent, none of the commercial paints or coating compositions can give a satisfactory finish appearance or cope with the high quality appearance requirement.
When a leveling agent is added to a composition for coatings capable of providing stain resistance, it is possible that the stain resistance of the coating composition decreases.
WO 98/07797 discloses a curable composition (&agr;) for coatings which comprises an epoxy group-containing resin (A) component, a carboxyl group-containing compound (B) component and a silicate (C) component as well as a composition derived from said composition by introducing a hydrolyzable silyl group into the (A) component, namely a curable composition (&bgr;) for coatings which comprises a hydrolyzable silyl group- and epoxy group-containing resin (A) component, a carboxyl group-containing compound (B) component and a silicate (C) component. However, though such compositions indeed provide good stain resistance, the stain resistance may be lowered by certain additives added in the step of paint or coating preparation. Also in cases where a leveling agent is added as the additive, the same problem may be encountered and it is necessary to select a leveling agent which will not lessen the stain resistance. Alternatively, a paint or coating is earnestly desired which is capable of providing a good appearance without adding any leveling agent, hence capable of retaining the stain resistance without any reduction in stain resistance due to the addition of a leveling agent.
SUMMARY OF THE INVENTION
In view of the above state of the art, the present invention has for its object to provide a curable composition for coatings which can provide coatings or paint films excellent in acid resistance, scratch resistance, stain resistance and heat curability, among others, with very good weather resistance and appearance. In particular, the curable composition for coatings of the present invention can preferably be used in top coat paint compositions for automobiles. In addition, the present invention provides a coated articles obtained from said curable composition for coatings and a resin composition for coatings.
The present invention provides a curable composition for coatings which comprises:
a component (A) consisting of a resin (A-1) obtained by mixing an epoxy group-containing compound (x) component and a carboxyl group-containing compound (y) component and/or a resin (A-2) based on an epoxy group- and carboxyl group-containing vinyl copolymer (z) component,
a component (B) consisting of a vinyl copolymer whose main chain substantially consists of a vinyl copolymer chain and which has, within the molecule thereof, at least one hydrolyzable silyl group bound to a carbon atom as represented by the following general formula (I):
[wherein R
1
represents a hydrogen atom or an alkyl group containing 1 to 10 carbon atoms, R
2
represents a hydrogen atom or a monovalent hydrocarbon group selected from among an alkyl group containing 1 to 10 carbon atoms, an aryl group containing 6 to 10 carbon atoms and an aralkyl group containing 7 to 10 carbon atoms and a represents an integer of 0 to 2], at one main chain terminus and/or on a side chain, and
a component (C) consisting of a silicon compound represented by the following general formula (VII):
(R
3
O)
4−b
SiR
4
b
(VII)
[wherein R
3
represents a hydrogen atom or an alkyl group containing 1 to 10 carbon atoms, an aryl group containing 6 to 10 carbon atoms or an aralkyl group containing 7 to 10 carbon atoms and the R
3
groups may be the same or different, R
4
represents an alkyl group containing 1 to 10 carbon atoms, an aryl group containing 6 to 10 carbon atoms or an aralkyl group containing 7 to 10 carbon atoms and when there is a plurality of R
4
groups, they maybe the same or different, and b represents an integer of 0 to 2], and/or a partial hydrolyzate condensate thereof.
The curable composition for coatings of the present invention preferably comprises 100 parts by weight of the component (A), 1 to 100 parts by weight of the component (B) and 1 to 100 parts by weight of the component (C).
Said (x) component preferably contains at least two epoxy groups per molecule and has an epoxy equivalent of 200 to 2,000 g/mole. It preferably contains at least one hydroxy group per molecule and has a hydroxy equivalent of 500 to 7,000 g/mole. Furthermore, it preferably contains at least one carboxyl group per molecule.
Said (y) component is preferably a vinyl copolymer ((y)-i component) containing, on an average, two or more carboxyl groups per molecule.
Said (y)-i component preferably contains at least two epoxy groups per molecule and has an epoxy equivalent of 200 to 2,000 g/mole. It preferably contains at least one hydroxy group per molecule and has a hydroxy equivalent of 500 to 7,000 g/mole.
The (y) component is preferably an oligomer compound ((y)-ii component) containing at least two carboxyl groups per molecule and having a molecular weight of not more than 2,000.
Said (y)-ii component is preferably prepared by subjecting a polyol compound and an acid anhydride compound to half esterification.
The (z) component preferably contains at least one carboxyl group and at least two epoxy groups per
Ando Naotami
Nakamura Seigo
Nambu Toshiro
Connolly Bove Lodge & Hutz
Jackson Monique R.
Kaneka Corporation
Thibodeau Paul
LandOfFree
Curable composition for coatings, coated articles and resin... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Curable composition for coatings, coated articles and resin..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Curable composition for coatings, coated articles and resin... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2604805