Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Patent
1999-02-03
2000-12-05
Pezzuto, Helen L.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
526301, 526310, 526321, 526322, 5263231, 5263232, 526328, 5263285, C08F11800
Patent
active
061568627
DESCRIPTION:
BRIEF SUMMARY
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
In recent years, the deterioration in the external appearance of paint films due to chemical and physical causes, such as etching by acid rain and scratching during cleaning of the paint film for example, has been seen as a problem in the field of automobile paints, for example.
Acrylic-melamine based top-coat paint compositions in which .epsilon.-caprolactone modified acrylic resin and specified low molecular weight polyols are used conjointly in the essential structural material of the paint film and in which soft segments are introduced by hardening with an alkoxy monomeric melamine (for example, Japanese Patent Kokai 64-66274, (1989)) have been suggested as a means of resolving these problems.
However, the abovementioned paint compositions are such that the paint film forming resin itself is modified with .epsilon.-caprolactone and so the paint film is softened and the scratch resistance can be improved, but the acid resistance is inadequate because alkoxy monomeric melamine is used, and this is inappropriate for dealing with severe acid rain in the future.
Furthermore, top-coat paint compositions which have .epsilon.-caprolactone modified acrylic resin and non-yellowing type blocked polyisocyanate compounds as essential components (for example, Japanese Patent Kokai H2-305873 (1990)) have also been suggested with the same end in view.
However, although both scratching resistance and acid resistance are improved with the abovementioned compositions, a blocked isocyanate compound is used for the crosslinking agent and so the paint film in fact liable to yellowing even though it is said to be a non-yellowing type, and in practice the non-yellowing properties are inadequate.
On the other hand, hardenable compositions which contain poly-functional 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 are 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.degree. C. in particular.
The aim of this invention is to provide heat-hardenable paint compositions with which paint films which have excellent scratching resistance, acid resistance, yellowing resistance and weather resistance can be formed in order to resolve the problems outlined above.
SUMMARY OF THE INVENTION
The present invention provides the following heat-hardenable paint compositions: copolymer of hydroxyl group value from 20 to 200 mg KOH/g, being a copolymer of from 5 to 70 wt % hydroxyl group containing vinyl based monomer (a-1) which can be represented by general formula (1) which is indicated below and from 95 to 30 wt % other vinyl based monomer (a-2), and (B) 1,3,5-triazine-2,4,6-triscarbamic acid ester which can be represented by the general formula (2) which is indicated below, or an oligomer thereof, characterized in that the mol ratio of 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. ##STR1## (In this formula, X.sup.1, X.sup.2 and X.sup.3 each independently represent a hydrogen atom or a methyl group. Moreover j is an integer of value from 0 to 2, m is an integer of value from 3 to 5, and n is an integer of value from 0 to 5. However, j and n cannot both be 0.) 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
REFERENCES:
patent: 5574103 (1996-11-01), Wu et al.
patent: 5726254 (1998-03-01), Wu et al.
Luer Ingo
Nukita Akito
Shibatoh Kishio
BASF Coatings AG
Pezzuto Helen L.
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