JPS6322217B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a heat-resistant resin composition that has a high resin concentration, has good storage stability, and provides molded products such as coatings and films with excellent surface smoothness. It is well known that polyamide-imide resins have excellent heat resistance, chemical resistance, and mechanical properties, and are widely used in practical applications such as heat-resistant wire coatings, metal surface protection coatings, and films. However, this resin is generally soluble only in expensive and special solvents such as N-methyl-2-pyrrolidone and N,N-dimethylformamide, which makes the resin composition as a product expensive. In some cases, there may be restrictions on usage. If the amount of solvent that cannot be used as a coating film-forming component can be reduced and the resin concentration can be increased, substantial cost reductions can be achieved, and at the same time, it can also contribute to resource conservation. One method for increasing the resin concentration is to lower the molecular weight of the resin. Polyamide-imide resin compositions currently in practical use have a reduced viscosity of resin exceeding 0.4 and a resin concentration of 10 to 30% by weight.
(When the viscosity is 30±5 poise at 30°C). If the reduced viscosity is 0.4 or less, especially 0.35 or less, the resin concentration can be reduced to 35% by weight.
You can do more than that. However, if the molecular weight is simply lowered in this way, even though the resin concentration increases, the terminal functional group concentration of the resin increases, and as shown in the comparative example below, the viscosity of the resin composition decreases over time. As the temperature rises, it finally reaches gelation. If the viscosity increases over time, for example, when used as a metal surface protection paint, the viscosity must be adjusted by changing the initially set coating conditions or diluting the thickened resin composition with a solvent. In addition, the properties of the protective coating formed by volatilizing the solvent may change. Particularly when applied to circuit boards for electronic components, it is necessary to form a film with a thickness of several microns, and viscosity change is a major problem. In addition, when forming a desired molded product from a composition by heating, the molecular weight is rapidly increased from a small molecular weight to a high molecular weight with a decarbonation reaction, resulting in minute foaming and unevenness on the surface of the molded product. In addition to impairing the aesthetic appearance, it also deteriorates various mechanical and electrical performances as shown in the comparative example below. Also,
When applied as a paint for enameled wire, when winding a coil using a high-speed winding machine like in recent years,
Protruding parts due to foaming or the like cannot pass through the guide device, resulting in wire breakage, and when winding coils in a bobbin in an aligned manner, steps may occur, making it impossible to wind the coil as designed. In order to solve these problems, the present invention aims to improve the molecular weight of the resin, the type and amount of the storage stability improver, and the combination of this and the resin with respect to a composition with a high resin concentration using a polyamide-imide resin with a small molecular weight. This was achieved only through repeated detailed experiments regarding the reaction conditions, solvent composition, etc. That is, the present invention involves adding an alcohol to a heat-resistant resin having a reduced viscosity of 0.10 to 0.40, which is obtained by reacting a polyvalent isocyanate having two or more isocyanate groups in one molecule with a tribasic acid anhydride or a functional derivative thereof. After adding and heating reaction, a compound represented by the following general formula, R ₁ OOC (CH ₂ ) nCOOR ₂ (R ₁ and R ₂ are alkyl groups having 1 to 5 carbon atoms, n is an integer of 1 to 10) It relates to a heat-resistant resin composition obtained by dissolving it in a solvent containing the following. In the production of heat-resistant resin in the present invention,
From the viewpoint of heat resistance, mechanical properties, chemical properties, etc., it is preferable to use the equivalent of the isocyanate group in a slight excess with respect to the sum of the equivalents of the carboxyl group and the acid anhydride group. Even if the addition reaction is carried out, the storage stability will be poor. Considering the balance between the two, it is preferable that the equivalent of the isocyanate group is 0.8 to 1.1 relative to the sum of the equivalents of the carboxyl group and the acid anhydride group. ,
It is more preferred to react in substantially equal equivalent ratios of 0.95 to 1.08. Polyvalent isocyanates having two or more isocyanate groups in one molecule include aliphatic, alicyclic,
Aroaliphatic, aromatic and heterocyclic polyisocyanates, such as ethylene diisocyanate, 1,4-
Tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 1,12-dodecane diisocyanate, cyclobutene-1,3-diisocyanate, cyclohexane 1,3- and 1,
4-diisocyanate, isophorone diisocyanate 1,3 and 1,4-phenylene diisocyanate, 2,4- and 2,6-tolylene diisocyanate and mixtures of these isomers, diphenylmethane-2,4'-diisocyanate, diphenylmethane- 4,4'-diisocyanate, diphenyl ether-4,4'-diisocyanate, xylylene diisocyanate, naphthalene-1,4-diisocyanate, naphthalene-1,5-diisocyanate, 1-methoxybenzene-2,4-diisocyanate, diphenyl diisocyanate Enylsulfone-4,4'-
Diisocyanates and compounds having three or more isocyanate groups in one molecule obtained by multiplying these diisocyanates, polyphenylmethylene polyisocyanates (for example, obtained by treating a condensate of aniline and formaldehyde with phosgene), etc. It can be used without any particular restriction. Examples of tribasic acid anhydrides include general formulas (i) and
A compound shown in (ii) is used.

【formula】

[Formula] (X is -CR ₂ - (R=H, CH ₃ ), -CO-, -SO ₂
-, -O-, etc.) Specific examples of compounds represented by the structural formula of formula (i) or formula (ii) include trimellitic anhydride, 2-(3,4
-dicarboxyphenyl)-2-(3-carboxyphenyl)propane anhydride, (3,4-dicarboxyphenyl)(3-carboxyphenyl)methane anhydride, (3,4-dicarboxyphenyl) )(3
-carboxyphenyl)ether anhydride, 3,
Examples include 3',4-tricarboxybenzophenone anhydride. In addition, 1,2,4-butanetricarboxylic anhydride, 2,3,5-naphthalenetricarboxylic anhydride, 2,3,6-naphthalenetricarboxylic anhydride, 1,2,4-naphthalenetricarboxylic anhydride, Examples include 2,2',3-biphenyltricarboxylic anhydride. From the viewpoint of heat resistance and cost, it is preferable to use trimellitic acid anhydride. If necessary, a polybasic acid or a functional derivative thereof other than the above-mentioned tribasic acid anhydride or functional derivative thereof can be used in combination. Examples of polybasic acids include tribasic acids such as trimesic acid and tris(2-carboxyethyl)isocyanurate, dibasic acids such as terephthalic acid, isophthalic acid, succinic acid, adipic acid, sebacic acid, and dodecanedicarboxylic acid;
2,3,4-butanetetracarboxylic acid, cyclopentanetetracarboxylic acid, ethylenetetracarboxylic acid, bicyclo-[2,2,2]-oct-(7)-ene-2:3,5:6-tetracarboxylic acid Aliphatic and alicyclic tetrabasic acids such as acids, pyromellitic acid,
3,3',4,4'-benzophenonetetracarboxylic acid, bis(3,4-dicarboxyphenyl)ether, 2,3,6,7-naphthalenetetracarboxylic acid, 1,2,5,6 - naphthalenetetracarboxylic acid, ethylene glycol bistrimelitate,
2,2'-bis(3,4-dicarboxyphenyl)
Propane, 2,2',3,3'-diphenyltetracarboxylic acid, 3,4,9,10-perylenetetracarboxylic acid, bis(3,4-dicarboxyphenyl)
Aromatic tetrabasic acids such as sulfone, bis(3,4-dicarboxyphenyl)methane, thiophene-
Examples include heterocyclic tetrabasic acids such as 2,3,4,5-tetracarboxylic acid and pyrazinetetracarboxylic acid. In the present invention, functional derivatives of tribasic acid anhydrides or functional derivatives of polybasic acids are monoanhydrides, dianhydrides derived from tribasic acid anhydrides or polybasic acids,
Means ester, amide, chloride, etc. When reacting a polyvalent isocyanate having two or more isocyanate groups in one molecule with a tribasic acid anhydride or its functional derivative and, if necessary, with a polybasic acid or its functional derivative, it must be carried out in an organic solvent. is preferred, and examples of organic solvents include N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, didimethylsulfoxide, hexamethylphosphonamide, N-methyl-caprolactam, and nitrobenzene. , acetophenone, anisole, etc. are used. From the viewpoint of reactivity and performance of the resulting resin, it is preferable to use N-methyl-2-pyrrolidone as the synthesis solvent. The monomer concentration during synthesis is 40-80% by weight, especially 50-80% by weight.
It is preferable to carry out the reaction at 60% by weight. If the monomer concentration is less than 40% by weight, excess solvent must be evaporated after synthesis in order to obtain a composition with a high resin content, which is one of the objects of the present invention, which tends to be economically disadvantageous. Moreover, if it exceeds 80% by weight, the reaction tends to progress too quickly and become difficult to control. Here, the monomer concentration refers to the polyvalent isocyanate having two or more isocyanate groups in one molecule at the start of the reaction, the tribasic acid anhydride or its functional derivative, and the polybasic acid or its functional derivative used as necessary. The sum of the weights represents the weight fraction occupied in the system. The reduced viscosity of the resin obtained by reacting a polyvalent isocyanate having two or more isocyanate groups in one molecule with a tribasic acid anhydride or its functional derivative is 0.10 to 0.40, and can be 0.15 to 0.35. More preferred. If the reduced viscosity is less than 0.10, storage stability, heat resistance, and other practical performance will be insufficient.
If it exceeds 0.40, the resin concentration will decrease, making it impossible to satisfy one of the objects of the present invention. To adjust the reduced viscosity, prepare a calibration curve between the viscosity of the solution sampled from the reaction system (Gardner viscosity, absolute viscosity, etc.) and the reduced viscosity of the resin, and then measure the viscosity as appropriate during the reaction. can be done. Reduced viscosity is measured as follows. That is, 15 g of the resin solution (concentration approximately 10% by weight) immediately after synthesis is poured into water or methanol to form a precipitate.
Heat and dry at ℃ for 8 to 12 hours. Next, this solid resin was diluted with N,N-dimethylformamide to obtain a solution with a concentration of 0.5 g/dl, and the following was carried out using a conventional method.
Calculated by measuring the flow time using an Ostwald viscometer or Canon Fuenske viscometer at 30°C. If the reduced viscosity exceeds 0.40, the composition should be
Almost no change in viscosity is observed even after storage at 60°C for several months. On the other hand, if the reduced viscosity is set to 0.40 or less, especially if it is 0.35 or less, the viscosity increases or gels during storage as described above, causing a serious problem in practice. In order to solve this problem of storage stability, it is extremely effective to add and react alcohols. At that time, simply adding and mixing alcohols does not improve the storage stability, and the temperature is preferably 40°C or higher, more preferably 50 to 150°C, even more preferably 80 to 120°C, and preferably 0.1 to 20 hours. It is necessary to carry out the heating reaction more preferably for 0.5 to 10 hours, still more preferably for 1 to 6 hours. The reason why storage stability is improved by addition of alcohol is not fully clear, but as shown in the following formula, the isocyanate group at the end of the molecular chain is blocked and stabilized by alcohol. It is. 〜〜〜〜(Resin)〜〜〜〜NCO+ROH―→ 〜〜〜〜(Resin)〜〜〜〜NHCOOR Note that simply adding and mixing alcohols at around room temperature does not improve storage stability, but this is the reason. This is thought to be because this terminal isocyanate group is not sufficiently blocked. Furthermore, if the reaction is heated at a higher temperature or for a longer time than necessary, the heat resistance and other practical performance will deteriorate. One reason for this is that if the reaction is carried out at too high a temperature or for a long time, the amide and imide bonds in the molecular chain undergo an alcoholysis reaction with the alcohol, causing the bonds to cleave, as shown in the following formula. I wonder if there is. 〜〜〜〜CONH〜〜〜〜＋ROH―→ 〜〜〜〜COOR＋H ₂ N〜〜〜〜 The amount of alcohol added is preferably 0.1 to 10% by weight, more preferably 0.5 to 5% by weight, and even more preferably 1 to 3% by weight based on the resin.
If it is less than 0.1% by weight, the effect of improving storage stability will be poor, and if it exceeds 10% by weight, practical properties such as heat resistance will deteriorate. Alcohols include methanol, ethanol, n-propanol, isopropanol, n-
Butanol, i-butanol, t-butanol,
Methyl cellosolve, ethyl cellosolve, methyl carbitol, benzyl alcohol, cyclohexanol, etc. are used. Among these, methanol, ethanol, propanol or butanol are particularly effective. The resin thus obtained is heat resistant by dissolving it in a solvent containing the compound represented by the above general formula, preferably containing 1 to 35% by weight, more preferably 5 to 25% by weight of this compound. It is considered to be a resin composition. When the compound represented by the above general formula is used as a solvent, molded products such as enameled wires have no foaming or unevenness on the surface, and the thickness is uniform and smooth, compared to when this is not used as a solvent. ,Physical,
Excellent chemical and electrical performance. The compound represented by the above general formula may be used alone as a solvent, or may be used in combination with another solvent. When used in combination with other solvents, it is preferably used in the range of 1% to 50% by weight in the solvent from the viewpoint of resin solubility and effect of imparting smoothness to the surface of the molded product. Specific examples of the compounds represented by the above general formula include dimethyl malonate, diethyl malonate, diisopropyl malonate, dibutyl malonate, dipentyl malonate, dimethyl succinate, diethyl succinate, diisopropyl succinate, dibutyl succinate, dipentyl acid, dimethyl glutarate,
Diethyl glutarate, dipropyl glutarate, dibutyl glutarate, dipentyl glutarate, dimethyl adipate, diethyl adipate, dipropyl adipate, dibutyl adipate, dipentyl adipate, dimethyl maleate, diethyl maleate, dipropyl maleate, maleic acid Dibutyl, dipentyl maleate, dimethyl fumarate, diethyl fumarate, dipropyl fumarate,
Examples include dibutyl fumarate, dipentyl fumarate, dimethyl pimelic acid, diethyl pimelic acid, and the like. Among these compounds, dimethyl succinate, dimethyl glutarate, dimethyl adipate,
It is preferable to use diethyl succinate, diethyl glutarate, and diethyl adipate. Examples of organic solvents that can be used in combination include, in addition to the organic solvents used during the resin synthesis described above, benzene, toluene, xylene, high-boiling aromatic hydrocarbons (for example, Nippon Oil's Hysol 100, Hysol 150, etc.), and γ.
-Butyrolactone as well as polyhydric alcohol derivatives represented by the general formula below can be used. R ₃ COO (CHR ₄ CH ₂ O) nH R ₃ COO (CHR ₄ CH ₂ O) n COR ₅ R ₃ O (CHR ₄ CH ₂ O) nR ₆ R ₃ O (CHR ₄ CH ₂ O) nH R ₃ COO ( CHR ₄ CH ₂ O) nR ₇ (However, in the above formula, R ₃ , R ₅ , R ₆ , R ₇ are lower alkyl groups, aryl groups or aralkyl groups,
R ₄ is hydrogen or a methyl group, and n is an integer from 1 to 3. ) Specific examples of compounds represented by this general formula include ethylene glycol monoacetate, propylene glycol monoacetate, diethylene glycol monoacetate, ethylene glycol diacetate, propylene glycol diacetate,
Diethylene glycol diacetate, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dipropyl ether, ethylene glycol dibutyl ether, propylene glycol dimethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dipropyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether , ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether,
Diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monoisopropyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate , diethylene glycol monoisopropyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoisopropyl ether acetate, dipropylene glycol monomethyl ether acetate, and the like. A curing accelerating catalyst can be added to the composition thus obtained, if necessary. Examples of curing accelerating catalysts include tertiary amines such as triethylamine, triethylenediamine, dimethylaniline, dimethylethanolamine, and 1,8-diaza-bicyclo(5,4,0)undecene-7 (or its organic acid salt). , organic tin compounds such as dibutyltin dilaurate and dibutyltin dioctoate, organic titanium compounds such as tetrabutoxytitanate, tetraisopropoxytitanate, or chelates and acylate compounds thereof, and trialkylphosphines. Particularly preferred are tertiary amines. Moreover, various additives such as a curing agent and a surfactant can be used in combination as necessary. Examples of the curing agent used include epoxy resins, amino resins, phenol formaldehyde resins, polyester resins having hydroxyl and/or carboxyl groups, and stabilized polyisocyanates obtained by adding active hydrogen compounds to isocyanate groups. The heat-resistant resin composition of the present invention has a solution viscosity of
When set at 25 to 30 poise (30℃), the resin concentration will be approximately 35 to 55% by weight, which is approximately 30% by weight of conventional products.
It has a high concentration compared to the above, and has excellent storage stability, surface smoothness of molded products, and various physical, chemical, and electrical properties, as shown in the examples below. The present invention will be explained below using Examples and Comparative Examples. Comparative Example 1 Diphenylmethane-4,4'-diisocyanate
459.8 g, trimellitic anhydride 351.3 g, and 1076 g of N-methyl-2-pyrrolidone were placed in 3 flasks equipped with a thermometer, stirrer, and nitrogen inlet tube, and heated to 90°C for 1.5 g.
The mixture was reacted for 1.5 hours at 100°C and for 1.0 hour at 120°C, and diluted by adding 37 g of xylene and 276 g of N,N-dimethylformamide. The resulting composition had a resin concentration (calculated from the amount of resin remaining after heating at 200° C. for 2 hours) of 37.1% by weight, and an initial viscosity of 34 poise. Comparative Example 2 7.4 g of methanol was added to 1000 g of the composition obtained in Comparative Example 1 immediately after synthesis, and the mixture was heated and reacted at 90° C. for 4 hours. The resulting composition had a resin concentration of 36.9% by weight and an initial viscosity of 34 poise. Example 1 Diphenylmethane-4,4'-diisocyanate
292.6 g of trimellitic anhydride, 223.6 g of trimellitic anhydride, and 685 g of N-methyl-2-pyrrolidone were placed in two flasks and reacted in the same manner as in Comparative Example 1. Next, 93 g of dimethyl glutarate, 40 g of dimethyl succinate,
The mixture was diluted by adding 66 g of N,N-dimethylformamide, and then 10.3 g of methanol was added, followed by a heating reaction at 90° C. for 4 hours. The resulting composition had a resin concentration of 37.0% by weight and an initial viscosity of 32 poise (the proportion of the compound represented by the general formula R ₁ OOC(CH ₂ )nCOOR ₂ in the solvent was 15% by weight). Example 2 Diphenylmethane-4,4'-diisocyanate
294.1 g of trimellitic anhydride, 223.9 g of trimellitic anhydride, and 687 g of N-methyl-2-pyrrolidone were placed in two flasks and reacted in the same manner as in Comparative Example 1. Next, 17 g of dimethyl adipate, 49 g of dimethyl glutarate, 22 g of dimethyl succinate, and 106 g of N,N-dimethylformamide were added for dilution, and further, 8.3 g of methanol was added.
g and 2.1 g of ethanol were added thereto, and the mixture was heated and reacted at 100° C. for 5 hours. The resin concentration of the obtained composition was 37.4
The initial viscosity in weight percent was 33 poise (general formula
The proportion of the compound represented by R ₁ OOC(CH ₂ )nCOOR ₂ is 10% by weight in the solvent). Example 3 Diphenylmethane-4,4'-diisocyanate
249.4g, diphenyl ether-4,4'-diisocyanate 44.4g, trimellitic anhydride 224.2g,
687 g of N-methyl-2-pyrrolidone was placed in two flasks and reacted in the same manner as in Comparative Example 1. Next, 124 g of dimethyl glutarate, dimethyl succinate
53g, diluted with 19g of N,N-dimethylformamide, further added 7.8g of methanol, and heated at 90°C.
The mixture was heated and reacted for 4 hours. The resulting composition had a resin concentration of 36.9% by weight and an initial viscosity of 34 poise (the proportion of the compound represented by the general formula R ₁ OOC(CH ₂ )nCOOR ₂ in the solvent was 20% by weight). Example 4 Diphenylmethane-4,4'-diisocyanate
285.3g, trimellitic anhydride 196.2g, 3,3′,
36.6 g of 4,4'-benzophenonetetracarboxylic dianhydride and 687 g of N-methyl-2-pyrrolidone were placed in two flasks and reacted in the same manner as in Comparative Example 1. Next, 33 g of diethyl glutarate, 33 g of dimethyl glutarate, 33 g of diethyl succinate, 33 g of dimethyl succinate, N,N-dimethylformamide
Add 62g and dilute, and then add 10.4g of methanol,
2.6 g of isopropanol was added and the mixture was heated and reacted at 100° C. for 5 hours. The resin concentration of the obtained composition is
The initial viscosity was 37.1% by weight and 31 poise (the proportion of the compound represented by the general formula R ₁ OOC(CH ₂ )nCOOR ₂ in the solvent was 15% by weight). Storage stability of the compositions obtained in Examples 1 to 4. They were coated on a copper wire with a diameter of 1 mm by a conventional method within 30 hours after synthesis, and the furnace temperature was 260/360/400°C (inlet/center/ The properties (measured according to JIS C 3003) of the enamelled copper wire obtained by repeating baking at the outlet) seven times were compared with Comparative Examples 1 and 2 and conventional commercially available polyamide-imide varnish (Hitachi Chemical Co., Ltd.).
Table 1 shows a comparison with HI-405-30 manufactured by Co., Ltd.

[Table] Voltage was measured.
As is clear from Table 1, the composition of the present invention has excellent storage stability compared to Comparative Example 1, and
The surface condition and dielectric breakdown voltage are excellent compared to Comparative Examples 1 and 2. Furthermore, compared to conventional products, the surface condition is improved and the resin concentration is higher. As described above, the heat-resistant resin composition of the present invention has excellent heat resistance, high resin concentration, and good storage stability, and is suitable for use in heat-resistant wire coatings, metal surface protection coatings, films, and laminated products. , can be widely applied industrially as adhesives, etc.

Claims (1)

[Claims] 1. Reduced viscosity obtained by reacting a polyvalent isocyanate having two or more isocyanate groups in one molecule with a tribasic acid anhydride or a functional derivative thereof.
After adding alcohol to a heat-resistant resin of 0.10 to 0.40 and heating reaction, a compound represented by the following general formula R ₁ OOC (CH ₂ ) nCOOR ₂ (R ₁ and R ₂ are alkyl having 1 to 5 carbon atoms) group, n is an integer of 1 to 10). 2. The heat-resistant resin composition according to claim 1, wherein the polyvalent isocyanate having two or more isocyanate groups in one molecule is diphenylmethane diisocyanate or tolylene diisocyanate. 3. The heat-resistant resin composition according to claim 1 or 2, wherein the tribasic acid anhydride or its functional derivative is trimellitic anhydride. 4. The heat-resistant resin composition according to claim 1, 2, or 3, wherein the alcohol is methanol, ethanol, isopropanol, or butanol. 5. Claim 1, wherein the amount of alcohol added is 0.1 to 10 parts by weight per 100 parts by weight of the resin;
The heat-resistant resin composition according to item 2, 3, 4, or 5. 6. Claims 1, 2, 3, 4, 5, or 6, wherein the heating reaction conditions for the heat-resistant resin and alcohol are a temperature of 50 to 150°C and a time of 1 to 6 hours. The heat-resistant resin composition according to item 6. 7 The compound represented by the general formula R ₁ OOC(CH ₂ )nCOOR ₂ is dimethyl succinate, dimethyl glutarate,
The heat-resistant resin composition according to claim 1, 2, 3, 4, 5, or 6, which is dimethyl adipate, diethyl succinate, diethyl glutarate, or diethyl adipate. thing.