Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2002-06-12
2004-07-13
Harlan, Robert D. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S179000, C526S180000, C526S181000, C526S210000, C526S319000
Reexamination Certificate
active
06762259
ABSTRACT:
TECHNICAL FIELD
The invention described herein relates to a method of producing a living polymerized (co)polymer by polymerizing a polar unsaturated compound using an organic oxysalt compound as catalyst. These polymer and copolymer are very important ones as raw materials of polymer materials and functional polymers.
The invention relates particularly to compositions of thermosetting powder coatings, more particularly, to the compositions of thermosetting powder coatings having excellent storage stability (blocking resistance), external appearance (surface flatness, brightness, and transparency), physical property (hardness, scratch resistance, and recoating property), and chemical property (weather resistance, acid resistance, and solvent resistance) and to the compositions of thermosetting powder coatings which can provide baked coating films particularly suitable for use of coating vehicles.
BACKGROUND ART
Enormous number of researches have been made with regard to the polymerization of polar unsaturated compounds for many years. Among them, recently a number of researches on living polymerization catalysts have been conducted aiming at producing polymers having less narrow molecular weight distribution by controlling optionally and rigorously the molecular weight of polymers to be obtained and various polymerization catalyst systems have been developed which have the property of living radical polymerization, living anion or living coordination anion polymerization (for example, living radical polymerization catalysts: Koubunshi, vol.48, (7) pp 498-501 (1999); living anion and living coordination anion polymerization catalysts: Shin koubunshi Jikkengaku vol.2“Shin Koubunshi no Gousei•Hannou(1)—Fukakei koubunshi no Gousei—” pp 165-196, Kyouritu Shuppan Kabushikigaisha (1995)).
Many effective living polymerization catalysts have been developed and from the view point of “the number of produced polymer molecules corresponding to the number of molecules of polymerization catalyst used” in most cases only one polymer molecule is obtained from one molecule of polymerization catalyst, that is, stoichiometric polymerization is observed. This stoichiometric living polymerization requires one molecule of the polymerization catalyst to produce one polymer molecule which is not an efficient and effective method of production in the light of industrially practical use. On the other hand, in catalytic living polymerization wherein plural number of polymer molecules are produced by one molecule of polymerization catalyst it is possible to avoid or simplify the complicated processes of separating catalysts and control unfavorable effects on the polymer property to a minimum by reducing drastically the concentration of catalyst components remaining in the polymer produced. Furthermore, this method is a really practical one from the view point of reducing environmental load and catalyst cost. Actually, the polymerization catalyst systems of polar unsaturated compounds which have been practiced are composed of very small amount of radical generating agents (which mean the catalysts described herein) and a large amount of chain transfer agents. Although the polymerization does not proceed like living one, it produces very efficiently the number of polymer molecules comparable to the number of molecules of the chain transfer agents from one radical molecule.
The known examples of the catalytic living polymerization of polar unsaturated compounds are {circumflex over (1)} polymerization of methacrylate using alkali metal alkoxide as catalyst and alcohol as chain transfer agent (S. N. Lewis et al., Progress in Organic Coating 12, 1-26 (1984)) and {circumflex over (2)} polymerization of methacrylate and acrylate using quaternary ammonium salt or Lewis acid as catalyst and silyl ketene ketal as chain transfer agent (O. W. Webster et al., J.Am.Chem.Soc., 105, 5703 (1983) or Shin koubunshi Jikkengaku vol.2“Shin Koubunshi no Gousei•Hannou(1)—Fukakei koubunshi no Gousei—” pp 365-386, Kyouritu Shuppan Kabushikigaisha (1995)). However, the method {circumflex over (1)} is a good polymerization method for producing oligomers having average molecular weight of 500-3000 but cannot produce oligomers having average molecular weight greater than or equal to 3000 or (co)polymers by controlling their molecular weight and molecular weight distribution precisely. Furthermore, since this method uses alcohol as both chain transfer agent and polymerization solvent, transesterification proceeds simultaneously with polymerization. Therefore, there is a drawback that this method cannot apply to the monomers when the transesterification causes some problems. The method {circumflex over (2)} has not been practiced yet, because silyl ketene ketal is expensive and unstable and there are some problems in the production method.
As an important use utilizing the property of the (co)polymer which is obtained by the method of the present invention there are powder coatings and prior arts relating to them which will be explained in the following:
Solvent type coating materials have usually been used for painting bodies and those which satisfy various requirements have been developed and used in order to be utilized in the field of automobiles where rigorous quality specification is required.
Recently in the technical field of coating materials, shift to using powder coatings have been expected in place of solvent type coating materials in the light of local or global environment conservation, environment improvement of health and safety at work, prevention of fire and explosion, and resource conservation. And from the historical and social requests, as expectation for high function performance and diversification of powder coatings have been increased, high paint film performance (for example, weather resistance, acid rain resistance, and scratch resistance) of powder coatings comparable to solvent type coating materials have been requested. However, in spite of severe requests for paint film performance, powder coatings which satisfy these requests have not necessarily been placed on the market.
As specific examples of the conventional types of powder coatings there are those of epoxy resin and polyester resin. However, these coatings have not only problems in weather resistance but also in resistance against the acid rain which has recently become a particular problem and, therefore, these problems were regarded as critical in the field of painting automobile bodies.
For the purpose of eliminating the drawback, acrylic powder coatings was proposed in JP-B-48-38617 and remarkable improvement in weather resistance has been realized. Since then many researches have been made on the acrylic powder coatings, however, these acrylic powder coatings have not satisfied sufficiently external appearance property, physical property, chemical property, storage property, and particularly surface flatness and blocking resistance simultaneously. Reduction in melt viscosity is the most effective to improve the surface flatness, however, in order to reduce the melt viscosity it was necessary to lower a glass transition temperature by which method it was impossible to satisfy both the surface flatness and the blocking resistance.
For the purpose of providing the surface flatness and the blocking resistance simultaneously, thermosetting powder coatings composition (WO96/03464) is proposed which uses acrylic (co)polymer having narrow molecular weight distribution. It is surely possible to have the surface flatness and the blocking resistance simultaneously by narrowing the molecular weight distribution. However, according to the method of living polymerization which is described as an example of producing method of the acrylic (co)polymer used therein, due to the insufficient recoating property (adhesion property with top coatings at repainting and maintenance) the powder coatings, particularly as top coatings, did not show the effectiveness sufficiently. As another example of the production, an acrylic (co)polymer having the prescribed
Fujiyoshi Setsuko
Funaki Katsuhiko
Hara Isao
Hayashi Takaomi
Hirose Yoshiharu
Harlan Robert D.
Mitsui Chemicals Inc.
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