JPH0528726B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a thermosetting powder composition, and particularly to a composition that provides a cured product with excellent heat resistance. The composition is suitable for various molding materials, binders for producing laminated materials, element sealing materials, etc., and is particularly useful for impregnating and fixing various coils using a powder coating method. (Prior Art) Conventionally, heat-resistant thermosetting powder compositions used in the above-mentioned applications are known to have various compositions. Specifically, a composition consisting of a silicone resin, a silicone-modified epoxy resin, and a curing agent, a composition consisting of a polyimide resin, a polyimide-modified epoxy resin, and a curing agent, a composition consisting of a bismaleimide triazine resin, an epoxy resin, and a curing agent. ,
Composition consisting of a monomaleimide compound, a polymaleimide compound, and an epoxy resin
74327), a composition comprising a monomaleimide compound having a specific chemical structure and an epoxy resin (Japanese Patent Application Laid-Open No. 74328/1983), and the like are known. However, the conventional compositions as described above have the following drawbacks. That is, it is difficult to obtain a cured product with well-balanced heat resistance and mechanical properties, and its uses are limited. In addition, it takes a long time at high temperatures to obtain a cured product, and for example, when the composition is used for impregnating and fixing coils, an extreme decrease in viscosity is observed during the curing process.
Leakage and sagging of the composition occur, and foaming and voids appear in the resulting cured product. Furthermore, the obtained cured product has poor adhesion to metals, and when a modified resin is used, a complicated process is required for synthesis for modification. In addition, as a curing agent, for example, 3,
A coating obtained by curing a composition containing an acid anhydride such as 3',4,4'-benzophenonetetracarboxylic anhydride or a reaction product of dicyclopentadiene and maleic anhydride. The film is foamed and lacks gloss, making it impossible to obtain a coating film with the desired performance. (Problems to be Solved by the Invention) The present invention seeks to provide a new and improved composition that eliminates the conventional drawbacks as described above. (Means for solving the problems) The present invention provides (A) at least one imide group in the molecule.
10 to 90 parts by weight of a maleimide compound and/or its initial condensate, (B) 90 to 10 parts by weight of an epoxy resin,
(C) an effective amount of a curing agent consisting of at least one dicyandiamide-imidazole mixed system, and
(D) A thermosetting powder composition containing 30 to 250 parts by weight of a filler. In the present invention, examples of maleimide compounds having at least one, preferably two imide groups in the molecule include the compounds shown below. (i) Eq. (In the formula, R ¹ is a monovalent atom or group, R ² and R ³ are the same or different, and are a hydrogen atom, a halogen atom,
They are an alkyl group and an aryl group. ) Monomaleimide compound (ii) represented by formula (In the formula, R ⁴ is a divalent organic group not having a maleimide group, and R ² and R ³ are the same as above.) Bismaleimide compound (iii) represented by the formula (In the formula, R ⁵ and R ⁷ are the same or different divalent organic groups, R ⁶ is a trivalent organic group, R ² and R ³ are the above three
It's the same thing. m is a positive integer. ) Polyvalent maleimide compound (iv) represented by formula (In the formula, R ⁸ and R ⁹ are the same or different divalent organic groups, and R ² and R ³ are the same as above.n
is a positive integer. ) Polymaleimide compound (v) represented by the formula (In the formula, R ¹⁰ is a trivalent or higher polyvalent organic group, q is 3
The above positive integers, R ² and R ³ are the same as above. ) The monovalent atom or group represented by R ¹ in the above formula includes phenyl group, methoxyphenyl group, etc., and the halogen atom represented by R ² and R ³ Examples of the alkyl group and aryl group include a chlorine atom, a bromine atom, an iodine atom, a methyl group, an ethyl group, a propyl group, and a phenyl group. Divalent groups represented by R ⁴ , R ⁵ and R ⁷ include biphenyl, diphenylmethane, α,α′-dimethyldiphenylmethane, diphenyl ether,
Groups derived from diphenyl thioether, diphenyl ketone, diphenylamine, diphenyl sulfoxide, diphenyl sulfone, triphenyl phosphate, etc., alkylene groups, oxyalkylene groups, alkenylene groups, phenylene groups, cyclohexylene groups, etc., and hydrogen of these groups Examples of R ⁶ include groups in which atoms are partially substituted, and trivalent groups derived from the same compounds as mentioned above. Examples of R ⁸ and R ⁹ include groups selected from the groups exemplified for R ⁴ above. Furthermore, R ¹⁰ can include a residue derived from an aromatic hydrocarbon compound and an organic group bonded via an arbitrary atom or group. All of the various maleimide compounds described above can be synthesized by known methods. For example, the expression The polymaleimide represented by the formula (wherein R' is a divalent organic group) can be obtained by reacting 1 mole of diaminodiphenylmethane with 2 moles of bismaleimide. The maleimide compound and its initial condensate are not limited to one type, but two or more types may be used in combination. Next, as the epoxy resin, various conventionally known ones can be used. Specific examples of these epoxy resins include:
Bisphenol A type, bisphenol B type, bisphenol F type, phenol novolak type, cresol novolak type epoxy resin, glycidyl ether type epoxy resin, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin,
Cycloaliphatic epoxy resin, linear aliphatic epoxy resin,
Examples include heterocyclic epoxy resins, halogenated, especially brominated epoxy resins, and one or more selected from the group consisting of these resins are used. Among these, the preferred epoxy resin in the present invention is a bisphenol A type epoxy resin which is solid in normal state, has an epoxy equivalent of 450 to 800, and a melting point of 65 to 90°C. Specifically, Epicote 1001, Epicote 1002, Epicote 1003
(all are epoxy resin trade names manufactured by Yuka Ciel Epoxy Co., Ltd.). The ratio of the above-mentioned maleimide compound and/or its initial condensate to the epoxy resin is 10 to 10% for the former.
The latter is 90 to 10 parts by weight relative to 90 parts by weight, preferably 50 to 20 parts by weight to the former 50 to 80 parts by weight. The reason for this amount limitation is as follows. If the amount of maleimide compounds is too small, there will be disadvantages such as difficulty in obtaining a cured product with excellent heat resistance.On the other hand, if it is too large, the inorganic filler will have poor adhesion or fixation to metals. When kneading, the viscosity becomes high and it becomes difficult to disperse sufficiently uniformly.
In addition, cracks occur in the resulting cured product, which interferes with cutting work, and further problems arise, such as poor wettability to the object to be coated, making it impossible to obtain a smooth coating film. Regarding the mixed curing agent, which is the most important point in the present invention, it is essential that the combination is as shown below. (i) Mixed system of dicyandiamides and imidazoles In the present invention, it is necessary to use the curing agent in a mixed system in a specific combination as described above. cannot be achieved. The dicyandiamides herein include, for example, in addition to dicyandiamide, guanidine compounds synthesized from dicyandiamide and aromatic amine compounds. In addition, as imidazoles, 2-methylimidazole, 2-undecylimidazole, 2-
heptadecylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole,
1-benzyl-2-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-4-ethylimidazole, 1-cyanoethyl-undecylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2 -Undecylimidazolium trimellitate, 2-methylimidazolium isocyanurate, 2,4-diamino-6-[2-methylimidazolyl-(1)]ethyl-S-triazine, 2,4-
Diamino-6-[2-undecylimidazolyl-
(1)]-Ethyl-S-triazine, 2-phenyl-
Examples include 4-methyl-5-hydroxymethylimidazole. Among these, 1-cyanoethyl-2-undecylimidazolium trimellitate, 2,4-diamino-6-[2-undecylimidazolyl-(1)]-ethyl-S-triazine, and is particularly preferred. The usage ratio of each component in the above-mentioned mixed curing agent varies slightly depending on the type of curing agent. Specifically, the usage ratio of dicyandiamides and imidazoles is 4:1 to 1:1, preferably 3 to 2. :1
It is. The amount of this mixed curing agent used is an effective amount based on the total amount of components (A) and (B) above, specifically 0.01 to 20
% by weight. If the amount used is too small, the curing reaction will not proceed sufficiently, and the heating loss at the initial high temperature will also be large, making it impossible to obtain the desired heat resistance and causing cracks. When objects are exposed to high temperature atmospheres, oxidation,
Thermal decomposition will be accelerated. The fillers used in the present invention include inorganic materials such as silica, alumina, calcium carbonate, wollastonite, and mica, semi-cured or cured products of phenolic resin, and cured products of polyimide, polyphenylene sulfone, or polyether sulfone. Organic materials such as These can be used as fine powders of any particle size. This filler is an important component in the present invention, and a composition lacking this filler cannot achieve the purpose of the present invention. The amount of this filler is in the range of 30 to 250 parts by weight based on 100 parts by weight of the total amount of components (A) and (B). If the amount used is less than 30 parts by weight, shrinkage and curing shrinkage of the cured product cannot be sufficiently prevented, and cracks and cracks are likely to occur, and the powder material may flow out during the painting and curing process. Sagging occurs, making it difficult to obtain a uniform cured coating. Moreover, if it exceeds 250 parts by weight, the wettability to the adherend will be poor, a smooth coating film will not be obtained, and the adhesion will also deteriorate. The composition of the present invention essentially comprises (A) to (D) as described above.
However, if necessary, any component may be included within the range that does not impede the object of the present invention. Examples of optional components include pigments, curing accelerators, heat resistance imparting agents, anti-sagging agents, dispersion aids,
Examples include coating film modifiers and flame retardant imparting agents. The composition of the present invention can be prepared in substantially the same manner as conventional powder compositions. Specifically, it can be prepared by uniformly kneading the above components (A) to (D) (this may be done mechanically) and then pulverizing the mixture to a desired particle size as necessary. (Effects of the Invention) The cured product obtained from the composition of the present invention has an excellent balance of heat resistance and mechanical strength. When curing, it is possible to cure at a relatively low temperature and in a short time without the need for high temperature and long-time heating as in conventional methods, so there is no negative effect on viscosity, and as a result, a good cured product can be obtained. . The cured product has excellent adhesion or adhesion to painted surfaces of various materials such as metals and ceramics. By using the composition of the present invention, the intended purpose can be achieved without using modified compounds whose synthesis is complicated as constituent components. The composition of the present invention can be widely used as a molding material, a laminated material (as a binder), a sealing material, an adhesive material, an insulating material, and the like. (Examples and Comparative Examples) Next, Examples and Comparative Examples of the present invention will be given, but the present invention is not limited to these Examples. Note that all parts in the examples indicate parts by weight. Examples 1 to 14 and Comparative Examples 1 to 10 A maleimide compound, an initial condensate of the maleimide compound, an epoxy resin, a curing agent, and a filler were uniformly mixed using a kneader in the proportions shown in Table 1 below. . Then, it was pulverized by a conventional method to obtain a particle size distribution suitable for powder coating. When various physical properties of this pulverized product were investigated, the results shown in Table 1 below were obtained. The measurement method and evaluation of each physical property are shown below. (1) Gelation time Approximately 0.1 to 0.2 g of powder is filled into a circular recess of a metal plate heated to 150°C, and the time (seconds) it takes for the powder to gel is measured, and this is calculated as the gelation time. (based on JIS C2104). (2) Presence or absence of cracks An iron plate (20 mm x 150
The powder was applied to the area (mm x 3.2 mm). The coating amount was such that the film thickness after curing would be 0.3 to 0.5 mm. When the iron plate was kept at the same temperature and then cooled, a cured coating film was obtained. This cured coating film was examined for the occurrence of cracks. (3) Tensile shear strength Pre-degreased test piece (mild steel plate 100 x 20
The adhesive strength (shear strength) was measured at 3 mm). However, the tensile speed was set to 5 mm/min, and the measurement at high temperature was performed after holding the sample at the specified temperature for 10 minutes. The pressing force during crimping was 1Kg/15×10mm ² or a pinch pressure equivalent to 1Kg/15×10mm ² . (4) Heat Deflection Temperature (HDT) Test pieces were press-molded under specified conditions and heat-cured at 200°C for 1 hour and at 220°C for 1 hour. HDT of the obtained cured product was measured according to ASTM D648. (5) Heating weight loss rate The numerator of the heating weight loss rate as a fraction. Using differential thermal analysis, the amount of weight loss was calculated from the residue generated during 1 minute between 3 and 4 minutes after starting heating at 450°C. Ta. Denominator of fraction of heating weight loss rate The weight loss rate after heating at 350°C for 1 hour and 400°C for 20 minutes was determined by calculation.

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[Table] Bismaleimide initial polymer: manufactured by Mitsubishi Yuka Co., Ltd., trade name MB-190M Bisphenol A type liquid epoxy resin: manufactured by Yuka Ciel Epoxy Co., Ltd., trade name Epicoat 828 Bisphenol A type solid epoxy resin *1: Manufactured by Yuka Ciel Epoxy Co., Ltd.: Product name Epicoat 1001 Bisphenol A type solid epoxy resin *2: Manufactured by Yuka Ciel Epoxy Co., Ltd.: Product name Epicoat 1002 Cresol novolac type epoxy resin: Manufactured by Asahi Kasei Co., Ltd., product name ECN-280 C ₁₁ Z-AZINE: 2,4-diamino-6-[2-undecylimidazolyl-(1)]-ethyl-S-triazine Manufactured by Shikoku Kasei Co., Ltd. Product name C ₁₁ Z-CNS: 1-cyanoethyl-2-undecyl Imidazolium trimellitate, product name manufactured by Shikoku Kasei Co., Ltd. 2MZ-AZINE: 2,4-diamino-6-[2-methylimidazolyl(1)]-ethyl-S-triazine, product name manufactured by Shikoku Kasei Co., Ltd. Alumina fine powder: Manufactured by Pacific Random Co., Ltd., product name
LA-1200 Silica fine powder: Manufactured by Ryumori Co., Ltd., trade name A-1 Calcium silicate fine powder *1: Manufactured by Ryumori Co., Ltd., trade name
SW-400 Calcium silicate fine powder *2: Manufactured by Maruwa Biochemical Co., Ltd., product name ASB-4 Glass powder: Manufactured by Nippon Fellow Co., Ltd., product name XD-
9A-M Mica: Shiraishi Calcium Co., Ltd., product name C-1000 Acrylic acid ester oligomer: Nippon Carbide Kogyo Co., Ltd., product name XK-21

Claims (1)

[Claims] 1 (A) Maleimide compound having at least one imide group in the molecule and/or its initial condensate 10-90
parts by weight, (B) 90 to 10 parts by weight of an epoxy resin, (C) an effective amount of a curing agent consisting of at least one type of dicyandiamide-imidazole mixed system, and (D) 30 to 250 parts by weight of a filler. Thermosetting powder.