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
1999-03-09
2001-05-29
Seidleck, James J. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S375000, C525S437000, C525S438000
Reexamination Certificate
active
06239229
ABSTRACT:
FIELD OF THE INVENTION
This invention concerns heat-hardenable paint compositions and, more precisely, it concerns heat-hardenable paint compositions which are suitable as top-coat paints for use on automobiles.
BACKGROUND OF THE INVENTION
A pressing need for the development of paints which have excellent durability in terms of weather resistance and acid resistance in respect of rain marks caused by acid rain has arisen in recent years.
For example, paint compositions with hydroxyl group containing acrylic resin and/or polyester resin, alkyl etherified melamine resin, non-yellowing polyfunctional blocked isocyanate and organotin based compounds as the main components, of which the hardening reaction of the main resin and the crosslinking agent is complex and with which paint films which have excellent acid resistance and scratch resistance are obtained by taking the unreacted melamine resin and the unreacted hydroxyl groups into the crosslinks, have been disclosed in Japanese Patent Kokai H4-246483 (1992).
However, although non-yellowing isocyanate is used, the paint compositions referred to above can hardly be said to have a degree of yellowing which is satisfactory for a practical paint film, and neither is the actual degree of yellowing clarified in the illustrative examples. Moreover, the paint compositions referred to above contain alkyl etherified melamine resins and so the resistance to hydrolysis of the crosslink parts is poor and the acid resistance of the hardened paint films is inadequate.
Furthermore, hardenable compositions which contain polyfunctional hydroxyl group containing materials, 1,3,5-triazine-2,4,6-tris-carbamic acid esters and acid hardening catalysts have been disclosed in Japanese Patent Kokai H6-228305 (1994), and it is stated that paint films which release little formaldehyde and which have excellent acid resistance can be obtained.
However, these compositions are inadequate in terms of weather resistance and thermal stability, and paint film defects such as cracking and loss of gloss due to exposure to ultraviolet radiation are liable to occur with paint films which have been formed under hardening conditions of temperature above 140° C. in particular.
The aim of this invention is to provide heat-hardenable paint compositions with which paint films which have excellent acid resistance, weather resistance, heat resistance and yellowing resistance can be formed in order to resolve the problems outlined above.
SUMMARY OF THE INVENTION
As a result of thorough research, the inventors have discovered that the crosslinking bonds which are formed by the ester exchange of sterically protected secondary hydroxyl groups and carbamic acid esters are stable with respect to light and heat and chemically stable, and the invention is based upon this discovery.
That is to say, the present invention provides the following heat-hardenable paint compositions:
(1) A heat-hardenable paint composition which contains (A) polyol which has in each molecule two or more sterically protected secondary hydroxyl groups, being a polyol obtained by means of an esterification reaction of an epoxy group containing compound (A1) which has one epoxy group and which does not have a polymerizable unsaturated bond and a carboxyl group containing compound (A2) which has two or more carboxyl groups; and (B) a 1,3,5-triazine-2,4,6-tris-carbamic acid ester which can be represented by general formula (1) indicated below, or an oligomer thereof, wherein the mol ratio secondary hydroxyl groups originating from the aforementioned (A) component:NHCOOR groups originating from the aforementioned (B) component in the composition is from 1:3 to 3:1.
General Formula (1)
C
3
N
3
(NHCOOR)
3
(1)
(In this formula, R represents an alkyl group which has from 1 to 20 carbon atoms, an aryl group which has from 6 to 20 carbon atoms or an aralkyl group which has from 7 to 20 carbon atoms, and these groups may be the same or different.)
(2) A heat-hardenable paint composition which contains (A) polyol which has in each molecule two or more sterically protected secondary hydroxyl groups, being a polyol obtained by means of an esterification reaction of an epoxy group containing compound (A1) which has one epoxy group and which does not have a polymerizable unsaturated bond and a carboxyl group containing compound (A2) which has two or more carboxyl groups; (B) 1,3,5-triazine-2,4,6-tris-carbamic acid ester which can be represented by general formula (1) indicated below, or an oligomer thereof; and (C) acrylic polyol which has primary hydroxyl groups, wherein the mol ratio secondary hydroxyl groups originating from the aforementioned (A) component:hydroxyl groups originating from the aforementioned (C) component in the composition is from 100:0 to 100:100, and the mol ratio of all the hydroxyl groups originating from the aforementioned (A) and (C) component:NHCOOR groups originating from the afore-mentioned (B) component in the composition is from 1:3 to 3:1.
General Formula (1)
C
3
N
3
(NHCOOR)
3
(1)
(In this formula, R represents an alkyl group which has from 1 to 20 carbon atoms, an aryl group which has from 6 to 20 carbon atoms or an aralkyl group which has from 7 to 20 carbon atoms, and these groups may be the same or different.)
DETAILED DESCRIPTION OF THE INVENTION
In this invention, the term “(meth)acrylic” signifies “acrylic” and/or “methacrylic”.
Furthermore, the term “primary hydroxyl group” signifies a “hydroxyl group in a structure where two i hydrogen atoms are bonded to the carbon atom to which the hydroxyl group is bound”, and the term “secondary hydroxyl group” signifies a “hydroxyl group in a structure where one hydrogen atom is bonded to the carbon atom to which the hydroxyl group is bound”.
The epoxy group containing compounds (A1) used in the invention are compounds which have one epoxy group and no polymerizable unsaturated bond within the molecule, and they preferably have no functional group other than the epoxy group, although they may have such groups.
Actual examples of the epoxy group containing compounds (A1) include versatic acid glycidyl ester, p-tert-butylbenzoic acid glycidyl ester, tertiary fatty acid glycidyl esters, styrene oxide, cyclohexane oxide, glycitol and the C
3
-C
20
alkyl glycidyl esters, C
3
-C
20
alkyl glycidyl ethers and phenyl glycidyl ether. Varsatic acid glycidyl ester and p-tert-butylbenzoic acid glycidyl ester are preferred from among these compounds.
Commercial products can also be used for the epoxy group containing compound (A1). Actual examples of such commercial products include “Kardura E10” (trade name for varsatic acid glycidyl ester, manufactured by the Yuka Shell Epoxy Co.), “PES-10” (trade name for p-tert-butylbenzoic acid glycidyl ester, manufactured by the Fuso Kagaku Co.), and “Equatate 9G” and “Equatate 13G” (trade names for tertiary fatty acid glycidyl esters, manufactured by the Idemitsu Sekiyu Kagaku Co.).
A single epoxy group containing compound (A1) can be used alone, or two or more of these compounds can be used in combination.
The carboxyl group containing compounds (A2) used in the invention are compounds which have two or more terminal carboxyl groups in the molecule, and they preferably have no functional group other than the carboxyl groups, although they may have such groups.
Actual examples of the carboxyl group containing compounds (A2) include acrylic resins, polyester resins, fluorine resins and silicone resins. One of these can be used alone, or two or more can also be used in combination.
In those cases where the carboxyl group containing compound (A2) is an acrylic resin, the acrylic resin which contains carboxyl groups is obtained by the polymerization or copolymerization of vinyl type monomers which have carboxyl groups, such as acrylic acid, methacrylic acid, ethacrylic acid, propylacrylic acid, isopropylacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, maleic acid half-esters, itaconic half-esters and acrylic acid dimer for example.
Vinyl type monomers which do not have car
Luer Ingo
Nukita Akito
Shibatoh Kishio
Asinovsky Olga
BASF Coatings AG
Seidleck James J.
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