JPH0546370B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a polymaleimide resin having excellent curability and workability. The polymaleimide resin obtained by the present invention has a low softening point and is useful as a CFRP matrix resin, a heat-resistant molding material, a sliding member, a heat-resistant adhesive, a heat-resistant paint, and a sealant for laminated materials. BACKGROUND ART In recent years, materials with better heat resistance have been desired in the electric/electronic field and the field of transportation equipment such as aircraft and vehicles as equipment becomes more efficient, smaller and lighter. Conventionally, epoxy resins, maleimide resins, polyimide resins, etc. have been used in this field. However, although epoxy resins have excellent mechanical and electrical properties, they do not necessarily have sufficient heat resistance or curing speed. Furthermore, although polyimide resin has excellent heat resistance, it is difficult to mold because it is insoluble and infusible. N,N'-4,4'-diphenylmethane bismaleimide has high thermal stability, but it has poor solubility in solvents, and has a slow curing speed and requires long-term heating at high temperatures to fully cure. I have a problem that requires it. Also, the general formula, [In the formula, m is an integer of 0 to 4] Poly(phenylmethylene) polymaleimide has a lower softening point than N,N'-4,4'-diphenylmethane bismaleimide, and is easy to work with. excellent in sex,
It also has a slightly better solubility in solvents, but has the same problem of slow curing speed as N,N'-4,4'-diphenylmethane bismaleimide. The present invention was made to improve the curability and solvent solubility of conventional polymaleimides, and consists of 1 mol of aldehyde consisting of a mixture of 5 to 95% by weight of aromatic dialdehyde and 95 to 5% by weight of formaldehyde. For general formula (), [wherein, The present invention provides a method for producing a polymaleimide, which comprises performing an addition reaction with maleic anhydride to obtain a polyamic acid, and then cyclodehydrating the polyamic acid. In the practice of the present invention, one aromatic dialdehyde of the aldehydes used in the production of polyamine has the general formula () Compounds represented by, specifically 1,2-benzenedialdehyde, 1,3-benzenedialdehyde,
1,4-benzenedialdehyde is preferred, and it may have a substituent such as a halogen group or an alkyl group. The other formaldehyde may be formalin, which is an aqueous solution, or paraformaldehyde, which is a polymer thereof. The aromatic dialdehyde represented by the above formula () is 5 to 95% by weight, preferably 10 to 95% by weight of the aldehydes.
It is used in a proportion of 90% by weight. If the amount of aromatic dialdehyde used is less than 5% by weight, the effect of improving the curability of the resulting polymaleimide is small. 95 on the contrary
If it exceeds % by weight, the effect of improving solubility in solvents will not be sufficient. Next, aromatic amines include aniline, O-
Toluidine, m-toluidine, p-yluidine,
o-ethylaniline, o-isopropylaniline, p-butylaniline, o-anisidine, m-
Examples include anisidine, p-anisidine, o-phenetidine, chloranilines, promanilines, and the like. The reaction between aldehydes and aromatic amines is carried out in the presence of acidic catalysts such as mineral acids such as hydrochloric acid and sulfuric acid, organic acids such as oxalic acid and para-toluenesulfonic acid, and other organic acid salts. 2 to 60 moles of aromatic amine, preferably 3 to 50 moles
The condensation reaction is carried out in molar proportions at a temperature of 40-150° C. for 1-10 hours. After the reaction is completed, the reaction mixture is neutralized using an alkali such as sodium hydroxide, washed with water, and then excess aromatic amine is removed under reduced pressure to obtain a polyamine. The polyamines obtained are liquid to solid at room temperature, and mainly have structures represented by the following formulas () and (). [In the formula, X is the same as in formula (), and m is 0 to 4
]. In addition to the polyamines represented by the formulas () and (), the polyamine represented by the formula () is further condensed with an aromatic aldehyde, and is further reacted with an aromatic _amine . Polyamines represented by formula () and polyamines obtained by reacting formalin with polyamines represented by formula () [formula ()] can be obtained in a proportion of 40% by weight or less. [X in the formula is the same as in formula (); Y ₁ , Y ₂ ,
Y ₃ and Y ₄ are H or and Y ₁ ′, Y ₂ ′, Y ₃ ′ are H or and Y ₁ ″, Y ₂ ″, Y ₃ ″ are H or ]. [In the formula, X is the same as the formula (), and Z is H or

【formula】

[Formula] or

[Formula], where n is an integer of 5 or less]. It is difficult to separate polyamines represented by these formulas () to (). 1 mole of maleic anhydride is dissolved in a suitable organic solvent per 1 equivalent of the amino group of the mixture of these polyamines, and an addition reaction is carried out at 0 to 40°C for 0.5 to 2 hours to obtain a polyamic acid. N as an organic solvent,
Examples include N'-dimethylformamide, acetone, methyl ethyl ketone, dioxane, N,N'-dimethylacetamide, dimethyl sulfoxide, and N-methylpyrrolidone. Next, acetic anhydride is added as a dehydrating agent for this polyamic acid, a catalyst and a tertiary amine are added as necessary, and the dehydration and cyclization reaction is carried out by heating at 20 to 80°C for 1 to 5 hours. Polymaleimide is obtained. Examples of catalysts include alkali metal salts, alkaline earth metal salts, divalent nickel salts, divalent or trivalent iron salts, and cobalt salts. In addition, chlorides, bromides, carbonates, acetates, etc. of these metals can also be used. Tertiary amines include triethylamine, tri-n-
Propylamine, tri-n-butylamine, etc. can be used. The produced polymaleimide reaction solution is used to precipitate the polymaleimide using a precipitant such as water,
It is purified by washing with water or neutralizing with a basic substance such as sodium hydroxide, sodium carbonate, sodium bicarbonate, potassium hydroxide, etc. as necessary, and then drying. The thus obtained polymaleimide is generally a mixture, of which 60% by weight or more is represented by the following formulas () and (). [In the formula, X is a hydrogen atom, a halogen atom, or an alkyl group or alkoxy group having 1 to 4 carbon atoms, and MI is

[Formula] is a group] [In the formula, X is the same as the formula (), and m is 0 to 4
]. In addition to the polymaleimides represented by the formulas () and (), polymaleimides represented by the following formulas () and () coexist. [X and Z in the formula are the same as in formula (); Y ₁ ,
Y ₂ , Y ₃ , Y ₄ are H or and Y ₁ ′, Y ₂ ′, Y ₃ ′ are H or and Y ₁ ″, Y ₂ ″, Y ₃ ″ are H or ]. [In the formula, X and MI are the same as in formula (),
Z′ is H or

【formula】

[Formula] or

[Formula], where n is an integer of 5 or less]. Polymaleimide obtained by carrying out the present invention undergoes radical polymerization by heating to form a polymer. Furthermore, when an amine is used as a curing agent and heated, addition polymerization occurs in addition to the above-mentioned radical polymerization, giving a cured product with excellent heat resistance. Examples of amines used as curing agents include aniline, toluidine, xylidine, vinylaniline,
isopropenylaniline, phenylenediamine,
Diaminocyclohexane, ethylenediamine, trimethylenediamine, tetramethylenediamine,
Hexamethylene diamine, 4,7-dioxadecane-1,10-diamine, 4,4'-diaminodicyclohexylmethane, m-xylylene diamine, p
-xylylene diamine, 2,4-diaminotoluene, 2,6-diaminotoluene, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, bis(3-chloro-4-aminophenyl)methane , 2,2-bis(4-aminophenyl)propane, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfide,
4,4'-diaminodiphenylsulfone 1,5-diaminonaphthalene, bis(4-aminophenyl)
Methylphosphine oxide, 4-methyl-2,
4-bis(4-aminophenyl)pentene-1,
5-amino-1-(4'-aminophenyl-1,3,
3-trimethylindane, tris(4-aminophenyl)phosphate, 2,4-bis(4'-aminobenzyl)aniline, 2,2-bis[4-
(4″-Aminophenoxy)phenyl] Examples include polymers of propane and vinylanilines of dimer or higher type, polyvalent amines of condensates of aniline and formaldehyde, etc. The amount of this amine blended is 100 parts by weight of the polymaleimide. 5 to 100 parts by weight.In addition to the curing agent, the following components can be added to the polymaleimide obtained by carrying out the present invention as necessary. (1) Powder form reinforcing agents and fillers, such as metal oxides such as aluminum oxide and magnesium oxide, metal carbonates such as calcium carbonate and magnesium carbonate, diatomaceous earth powder, basic magnesium silicate, calcined clay, finely powdered silica, fused silica, Crystalline silica, carbon black, kaolin, finely powdered mica, quartz powder, metal hydroxides such as aluminum hydroxide, graphite, asbestos, molybdenum disulfide, antimony trioxide, etc.In addition, fibrous reinforcements and fillers, e.g. These include inorganic fibers such as glass fiber, rock wool, ceramic fiber asbestos, and carbon fiber, and synthetic fibers such as paper, pulp, wood flour, linters, and polyamide fibers.Use of these powdered or fibrous reinforcing materials or fillers. The amount varies depending on the application, but up to 500 parts by weight can be used for 100 parts by weight of polymerimide as a laminated material or molding material. (2) Colorants, pigments, flame retardants such as titanium dioxide, yellow carbon black, iron black, Inorganic phosphorus such as molybedene red, navy blue, ultramarine blue, cadmium yellow, cadmium red, red phosphorus, organic phosphorus such as triphenyl phosphate, etc. (3) In addition, the final coating film, adhesive layer, resin molded product, etc. Various synthetic resins can be blended for the purpose of improving the properties of the resin.For example, phenolic resin, alkyd resin, melamine resin, fluororesin, vinyl chloride resin, acrylic resin, silicone resin, polyester resin, etc.
Mention may be made of species or combinations of two or more species. The amount of these resins used is preferably within a range that does not impair the inherent properties of the polymaleimide of the present invention, that is, less than 50% by weight of the total resin amount. In addition, methods for blending various additives and synthetic resins with this polymaleimide include heating melt mixing, kneading using a roll, kneader, etc., mixing using an appropriate organic solvent, dry mixing, etc. . Hereinafter, the present invention will be explained in more detail with reference to Examples and Application Examples. Example 1 In a 500 ml four-necked flask equipped with a thermometer, condenser, dropping funnel, and stirrer, 28.1 g of 1,4-benzenedialdehyde (proportion to aldehydes) was placed.
70.6% by weight), 301.6g of aniline, and 18.3g of concentrated hydrochloric acid, then 37% formaldehyde aqueous solution.
31.6g was added dropwise. After the dropwise addition was completed, the mixture was reacted for 5 hours under reflux of water (temperature: 102°C). After the reaction is complete, add 10% sodium hydroxide aqueous solution 79.2
g was added into the flask, and stirring was continued for 5 minutes to form an alkaline solution in the system. Next, 500 ml of methyl isobutyl ketone was added and dissolved in the flask, and then washed with 300 ml of pure water three times in total to remove by-produced sodium chloride and excess sodium hydroxide. Next, the solution was heated under reduced pressure (100~1 mmHg/80~
Methyl isobutyl ketone and unreacted aniline were completely removed at 180°C, and the residue was poured off at 180°C and cooled to obtain 165 g of an orange solid. A solution obtained by dissolving 53.1 g of this polyamine in 159.3 g of acetone was placed in a dropping funnel. Maleic anhydride was added to a 500 ml four-necked flask equipped with a thermometer, condenser, dropping funnel, and stirrer.
48.6 g and 97.2 g of acetone were charged and stirred to dissolve maleic anhydride. Next, a polyamine solution dissolved in acetone was added dropwise while maintaining the temperature of the flask at 20 to 30°C, and after the dropwise addition was completed, stirring was continued at the same temperature for 30 minutes. Next, in this flask, add 0.5 g of nickel acetate,
11.3 ml of triethylamine and 57.4 g of acetic anhydride were added, and the mixture was stirred under reflux (65°C) for 2 hours to carry out a dehydration cyclization reaction. After the reaction is complete, the reaction product is poured into 1.5 liters of water to precipitate the polymaleimide, which is then separated, washed with a large amount of water, and dried to form a yellow-brown polymaleimide.
88.9g (yield 98.5%) was obtained. The softening point (capillary method) of this polymaleimide is
The temperature was 114-120℃. The infrared absorption spectrum of this polymaleimide is shown in FIG. 1, and the nuclear magnetic resonance spectrum is shown in FIG. Example 2 The same operation as in Example 1 was carried out except that 21.5 g of 1,4-benzenedialdehyde (52.8% by weight of aldehydes), 51.9 g of 37% formaldehyde aqueous solution, and 357.5 g of aniline were used, and a yellowish brown color was obtained. , a polymaleimide powder with a softening temperature of 99-104°C was obtained. Example 3 The same operation as in Example 1 was carried out except that 11.4 g of 1,4-benzenedialdehyde (33.2% by weight of aldehydes), 62 g of 37% formaldehyde aqueous solution, and 348.2 g of aniline were used, and yellowish brown, Polymaleimide powder with a softening temperature of 88-93°C was obtained. Example 4 The same operation as in Example 1 was carried out except that 4.9 g of 1,4-benzenedialdehyde (15.8% by weight of aldehydes), 70.1 g of 37% formaldehyde aqueous solution, and 348.6 g of aniline were used, and a yellowish brown color was obtained. , a yellow-brown polymaleimide powder with a softening temperature of 77-82°C was obtained. Example 5 The same operation as in Example 1 was carried out except that 21.5 g of 1,4-benzenedialdehyde (proportion of aldehydes: 52.8% by weight), 51.9 g of 37% formaldehyde aqueous solution, and 412 g of o-toluidine were used. ,
Polymaleimide powder with a softening temperature of 97-102°C was obtained. Example 6 The same operation as in Example 1 was carried out except that 32.2 g of 1,3-benzenedialdehyde (74.9% by weight of aldehydes), 29.2 g of 37% formaldehyde aqueous solution, and 312.8 g of aniline were used. Polymaleimide powder with a softening temperature of 115-120°C was obtained. Example 7 The same operation as in Example 1 was carried out except that 21.5 g of 1,3-benzenedialdehyde (52.8% by weight of aldehydes), 51.9 g of a 37% formaldehyde aqueous solution, and 412 g of m-toluidine were used. ,
Polymaleimide powder with a softening temperature of 91-97°C was obtained. Example 8 The same operation as in Example 1 was carried out except that 48.3 g of 1,2-benzenedialdehyde (87% by weight of aldehydes), 19.5 g of 37% formaldehyde aqueous solution, and 335.2 g of aniline were used. Polymaleimide powder with a softening temperature of 110-118°C was obtained. Comparative Example 1 The same operation as in Example 1 was carried out except that 1.4 g of 1,4-benzenedialdehyde (4.5% by weight of aldehydes), 81.1 g of 37% formaldehyde aqueous solution, and 373 g of aniline were used, resulting in a yellowish brown color. , a polymaleimide powder with a softening temperature of 77-82°C was obtained. Comparative example 2 37% formaldehyde 81.1g, aniline 372.4
Perform the same operation as in Example 1 except for using g.
A powder of poly(phenylmethylene) polymaleimide was obtained which had a yellowish brown color and a softening temperature of 70 to 75°C. Comparative Example 3 Addition of maleic anhydride and dehydration ring closure were carried out in the same manner as in Example 1 except that the polyamine was changed to 45 g of 4,4'-diaminodiphenylmethane.
A powder of N,N'-4,4'-diphenylmethane bismaleimide having a melting point of 149-151°C was obtained. Application example 1 100 parts of the polymaleimide obtained in Example-1, 4,
Roll 20 parts of 4'-diaminodiphenylmethane and 100 parts of fused silica as a filler (temperature 120-140
℃) for 5 minutes, and the mixture was ground using a grinder. Table 1 shows the results of examining the gelation time at a temperature of 160°C using a culastometer. In addition, the powder was placed in a mold and compression molded using a press molding machine for 10 minutes at 200°C and 100 kg/cm ² to obtain a molded product measuring 12.7 mm long, 127 mm wide, and 6.4 mm high. Ta. Table 1 shows the heat distortion temperature of this molded product. Next, this molded product was stored in a greenhouse at 250° C. for 10 hours to be post-cured to obtain a cured product having the physical properties shown in Table 1. Application Examples 2 to 8 Powder was obtained in the same manner as in Application Example 1 above, except that the polymaleimide was replaced with that obtained in Examples 2 to 8. After checking the gelation time, a molded product was obtained, and then post-cured. A cured product was obtained. Comparative Application Example 1 Powder was obtained in the same manner as Application Example 1 except that the polymaleimide obtained in Comparative Example 1 was replaced, and after checking the gelation time, a molded product was obtained, and then post-cured and cured. I got something. Comparative Application Example 2 A powder was obtained in the same manner as Application Example 1 except that the polymaleimide was replaced with the poly(phenylmethylene) polymaleimide obtained in Comparative Example 2, and after checking the gelation time, a molded product was obtained. Subsequently, post-curing was performed to obtain a cured product. Comparative Application Example 3 100 parts of N,N'-4,4'-diphenylmethane bismaleimide obtained in Comparative Example 3 and 22 parts of 4,4'-diaminodiphenylmethane were heated to 150°C and heated with stirring. A viscous prepolymer was obtained by reacting for 10 minutes. A powder was obtained using 122 parts of the cooled and pulverized prepolymer and 100 parts of silica in the same manner as in Application Example 1. After examining the gelation time, a molded product was obtained, and then post-cured to obtain a cured product.

【table】 [Brief explanation of the drawing]

FIG. 1 is an infrared absorption spectrum diagram of the polymaleimide obtained in Example 1 of the present invention, and FIG. 2 is its nuclear magnetic resonance spectrum diagram.

Claims (1)

[Scope of Claims] 1 For 1 mole of aldehydes consisting of a mixture of 5 to 95% by weight of formaldehyde and 95 to 5% by weight of aromatic dialdehyde, the general formula: [In the formula, X is a hydrogen atom, a halogen atom, or an alkyl group or an alkoxy group having 1 to 4 carbon atoms] A polyamine is obtained by reacting an aromatic amine represented by the following in a proportion of 2 to 60 moles, and then the polyamine is A method for producing polymaleimide by subjecting a polyamic acid to an addition reaction with maleic anhydride to obtain a polyamic acid, and then cyclodehydrating the polyamic acid. 2 Polymaleimide has the general formula Polymaleimide shown by Claim 1 is characterized in that it is a mixture containing at least a polymaleimide represented by
[wherein X is a hydrogen atom, a halogen atom, or an alkyl group or an alkoxy group having 1 to 4 carbon atoms; m is an integer from 0 to 4].