Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Patent
1998-07-21
2000-02-15
Niland, Patrick D.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
524 86, 524 87, 524 91, 524 92, 524 94, 524323, 524589, 524590, 524 59, 524839, 524840, 525123, 525124, 525455, C08J 300, C08K 320, C08L 7500, C08F 830, C08F28304
Patent
active
060254335
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to thermosetting paint compositions which are resistant to yellowing due to brass, and more specifically it relates to single pack thermosetting paint compositions suitable as top finishing coat paints for automobiles.
PRIOR ART
In recent years rain stains due to acid rain and abrasions produced when washing cars have become a problem, and the development of paints to resolve this problem has become urgent.
In Japanese Unexamined Patent 4-2464 83 a paint composition is recorded in which the main components are a hydroxyl-group-containing acrylic resin and/or polyester resin, an alkylated melamine resin, an oxime-blocked isocyanate and an organotin compound, giving a paint composition which gives paint films of outstanding acid resistance and scratch resistance is obtained by crosslinking the unreacted melamine and unreacted hydroxyl groups.
However, because an oxime derivative is used as the isocyanate blocking agent in this paint composition yellowing after stoving and yellowing due to brass are problems. Yellowing after stoving here is the phenomenon of yellowing of the paint film after stoving when forming the hardened paint film, and yellowing due to brass is the phenomenon of yellowing of the paint or of the stoved paint film due to contamination with copper ions eluted from bras components present in the paint-making process or in some of the paint piping, valves and/or couplings in the painting line, for example. The reason for yellowing due to brass is thought to be that oxime derivatives used as isocyanate blocking agents form complexes with copper ions.
Similarly, in WO95/06674 a thermosetting paint composition is recorded which does not include an amino resin, in which an acrylic resin is employed as the principal resin with a blocked isocyanate blocked with a pyrazole derivative, and it is claimed that this gives paint films of outstanding acid resistance and resistance to yellowing after stoving.
However, this paint composition is inadequate in low-temperature curability and the weather resistance of the paint films is inadequate. Moreover, it is not claimed that paint films of outstanding resistance to yellowing due to brass are obtained.
In Japanese Unexamined Patent 5-86164 a thermosetting composition is described which contains a blocked isocyanate in which the isocyanate group is blocked with a pyrazole or imidazole derivative, and a primary or secondary polyamine.
However, this thermosetting composition is a thermosetting composition for adhesives, and paint film performance is inadequate when it used as a paint. Moreover, it is not claimed that it gives paint films of outstanding resistance to yellowing due to brass.
The purpose of the present invention is to offer thermosetting paint compositions resistant to yellowing due to bras which have outstanding resistance to yellowing due to brass and low-temperature curability, and can form paint films of outstanding yellowing after stoving, acid resistance, scratch resistance, solvent resistance, adhesion and appearance.
SUMMARY OF THE INVENTION
The present invention is the following thermosetting paint compositions.
(1) A thermosetting paint composition, which is a thermosetting paint composition which is resistant to yellowing due to brass, characterized in that the paint-film-forming components include can react with an isocyanate group, at 49.6-90 wt %, groups blocked by an azole blocking agent, at 9.6-50 wt %,
(2) A thermosetting paint composition according to (1) above, in which the functional groups in component (A) are hydroxyl groups, amino groups, epoxy groups, amide groups, urethane groups or active methylene groups.
(3) A thermosetting paint composition according to (1) above, in which component (A) is an acrylic resin which contains hydroxyl groups.
(4) A thermosetting paint composition according to (1) above, in which component (A) is a polymer which includes a structural unit represented by the general formula (1) ##STR1## (In the formula R.sup.1 -R.sup.5, which
REFERENCES:
patent: 5279862 (1994-01-01), Corcoran et al.
Monma Yasuhiro
Mori Souichi
Shibatoh Kishio
BASF Coatings AG
Niland Patrick D.
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