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
2000-04-04
2002-05-14
Nutter, Nathan M. (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...
C525S206000, C525S207000, C525S208000, C525S213000, C525S214000, C525S255000, C525S220000, C525S221000, C525S222000, C525S223000, C525S227000, C525S231000, C525S232000, C525S240000, C525S241000
Reexamination Certificate
active
06388012
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to a thermosetting powder paint composition, more particularly, to a thermosetting powder paint composition which has excellent storage stability (blocking-resistance and the like), appearance properties (cratering-resistance, cissing-resistance, smoothness, sharpness and the like), physical properties (hardness, scratch-resistance and the like) and chemical properties (weather-resistance, acid-resistance, solvent-resistance and the like) and particularly can provide a baked paint film suitable for vehicle painting use.
(2) Description of the Prior Art
Conventionally, solvent type paints are used for painting articles, and paints satisfying various requirements for use in fields such as automobiles and the like wherein strict qualities are required have been developed and used.
Recently, in the technical field of paints, change from solvent type paints to powder type paints (hereinafter, referred to as “powder paint”) has been expected from the standpoints of local or global environmental protection, labor safety, environment improvement, prevention of fire and explosion, resource saving and the like. Further, along with an increase in expectation of high ability and variety of powder paints owing to historical or social requirements, powder paints have been required to exhibit high-grade paint film abilities (e.g., weather-resistance, acid rain-resistance, scratch-resistance and the like) corresponding to those of solvent type paints. However, irrespective of increased strictness of paint film abilities required for powder paints, it is not necessarily been found that powder paints completely satisfying these requirements have been available commercially. As specific examples of conventional powder paints, epoxy resin and polyester resin powder paints are, for example, listed. However, these paints not only have poor weather resistance but also poor resistance against acid rain which has turned into problems particularly recently, causing problems in the fields of automobile body paintings and the like.
For improving these defects, U.S. Pat. No. 3,954,898 (Japanese Patent Application Publication (JP-B) No. 48-38617) suggested an acrylic powder paint and realized remarkable improvement of weather-resistance. Thereafter, various studies have been made regarding acrylic powder paints. However, these acrylic powder paints did not fully satisfy simultaneously appearance properties, physical properties, chemical properties and storage stability, particularly smoothness and blocking-resistance. For improving smoothness, it is most effective to decrease melt viscosity. However, for decreasing melt viscosity, glass transition temperature should be lowered, and in such a method, it is impossible to satisfy both smoothness and blocking-resistance simultaneously.
Therefore, in conventional acrylic powder paints, an acryl polymer which is liquid at normal temperature (having low Tg) is used as a flow controlling agent for the purposed of improving smoothness and preventing cratering. Such studies have long been conducted, and there have been suggested paints or resin compositions for improving appearance properties, physical properties and chemical properties (Japanese Patent Application Laid-Open (JP-A) No. 57-49672, U.S. Pat. Nos. 5,523,349 and 5,648,117 (JP-A No. 7-179789) and the like). Further, as reactive flow controlling agents, there have been suggested compositions which contain reactive functional groups such as an amino group, carboxyl group, hydroxyl group, epoxy group and the like, in the molecule, and improve paint film physical properties by reacting with main components or hardener components in forming a paint film (U.S. Pat. No. 5,212,245 (JP-A No. 8-325480), WO 97/23573 (JP-A No. 9-227799) and the like). However, these flow controlling agents are all liquids at normal temperature (having low Tg), and are causes of reduction in the blocking-resistance of a paint. Further, these flow controlling agents are viscous liquids at normal temperature, causing problems also in workability in producing paints.
Recently, for improving such problems, flow controlling agents have been developed in which flow controlling components are adsorbed onto silica particles or wax to formulate them as a solid form (U.S. Pat. No. 5,735,944). However, also regarding these solid flow controlling agents, those in which flow controlling components are adsorbed onto silica particles have problems in transparency, appearance and the like of the paint film, and those in which flow controlling components are adsorbed onto wax have problems in scratch-resistance, re-coating property and the like. Therefore, such solid flow controlling agents have not provided a thermosetting powder paint composition satisfying all of storage stability, appearance properties, physical properties, chemical properties and the like.
SUMMARY OF THE INVENTION
The present invention provides, in view of the above-described problems of the conventional prior art, a thermosetting powder paint composition (for example, an acrylic thermosetting powder paint composition) having excellent storage stability, appearance properties, physical properties and chemical properties. Particularly, the present invention provides a thermosetting powder paint composition (for example, an acrylic thermosetting powder paint composition) which is suitably applied to painting, particularly to top painting of bodies of vehicles such as automobiles and the like and parts of vehicles such as automobiles and the like (aluminum wheel, wiper, pillar, door handle, fender, bonnet, air spoiler, stabilizer, front grill and the like).
More specifically, a thermosetting powder paint composition is provided which enables manifestation of excellent blocking-resistance in storing of a powder paint composition simultaneously with manifestation of excellent appearance properties when the paint composition is coated to give a paint film, which has been difficult to be realized by compounding a solid flow controlling agent of the prior art or a liquid flow controlling agent of the prior art into a powder paint composition.
The present inventors have intensively studied in order to solve the above-described problems of the prior art, and resultantly have developed a solid flow controlling agent (C) which is solid at 20 only composed of a vinyl-based polymer, particularly, a (meth)acrylic vinyl polymer without using raw materials such as silica particles, wax and the like and have found that a thermosetting powder paint composition (for example, an acrylic thermosetting powder paint composition) having excellent storage stability, appearance properties, physical properties and chemical properties can be provided by using the component (C), completing the present invention.
The present invention is specified by the following subjects [1] to [16].
[1] A thermosetting powder paint composition comprising (A) a resin composition component, (B) a hardener component and (C) a solid flow controlling component which is solid at 20, wherein
the above-mentioned component (A) contains a resin composition component having reactivity with the component (B),
the above-mentioned component (B) contains a hardener having reactivity with the component (A),
the above-mentioned component (C) contains a vinyl polymer, and
the relation between the solubility parameter SP
A
of the component (A) and the solubility parameter SP
C
of the component (C) satisfies the following numerical formula (1) and the following numerical formula (2) simultaneously:
8
≦SP
A
≦13 (1)
7
≦SP
C
<SP
A
(2).
[2] The thermosetting powder paint composition according to [1] wherein the composition ratio of the resin composition component (A), the hardener component (B) and the solid flow controlling agent component (C) is controlled so that the amount of the component (C) is from 0.01 to 10% by weight based on the total weight of the component (A) and
Kikuta Yoshio
Matsumoto Tsuyoshi
Miyawaki Takahisa
Mizoguchi Mitsuyuki
Sakayama Hiroyuki
Burns Doane Swecker & Mathis L.L.P.
Mitsui Chemicals Inc.
Nutter Nathan M.
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