WO2010107045A1

WO2010107045A1 - Polyimide resin, curable resin composition, and cured object obtained therefrom

Info

Publication number: WO2010107045A1
Application number: PCT/JP2010/054499
Authority: WO
Inventors: 誠一宇野; 栄寿一ノ瀬; 聡子伊東
Original assignee: Dic株式会社
Priority date: 2009-03-18
Filing date: 2010-03-17
Publication date: 2010-09-23
Also published as: JPWO2010107045A1; TW201037001A

Abstract

A thermosetting resin composition which is soluble in general solvents and can give a cured object (cured coating film) that highly transmits light ranging from visible light to the ultraviolet region around 300 nm; and a polyimide resin suitable for use in preparing the composition. The polyimide resin is obtained by reacting an isocyanurate-type polyisocyanate (a1) synthesized from an isocyanate having an aliphatic structure with a tricarboxylic acid anhydride (a2) having an aliphatic structure. The curable resin composition contains the polyimide resin. A cured object obtained from the composition is provided.

Description

Polyimide resin, curable resin composition and cured product thereof

The present invention relates to a polyimide resin, a curable resin composition containing the polyimide resin, and a cured product thereof. Specifically, the present invention is a field that requires transparency in addition to heat resistance, for example, a field for optical materials, a solder resist material for printed wiring boards, a protective material and insulation for household appliances such as refrigerators and rice cookers. Materials, liquid crystal displays and liquid crystal display elements, organic and inorganic electroluminescent displays, organic and inorganic electroluminescent elements, light emitting diodes, electronic paper, solar cells, optical fibers, optical waveguides and other protective materials, insulating materials, adhesives, and reflective materials The present invention relates to a polyimide resin that can be suitably used in the field of display devices such as liquid crystal alignment films and protective films for color filters, a curable resin composition containing the polyimide resin, and a cured product thereof.

Polyimide resin is excellent in heat resistance and mechanical properties, and has been used in various fields mainly in the electrical and electronic industries. In recent years, it has been used as a general-purpose solvent such as EDGA (diethylene glycol monoethyl ether acetate) for the purpose of reducing the burden on the environment. The ability to dissolve has been sought. In addition, polyimide resins are expected to be used in fields where transparency of cured products such as liquid crystal displays is required in view of heat resistance and mechanical properties. In these fields, for example, light transmittance from the visible to the ultraviolet region (around 300 nm) is required.

As a polyimide resin that dissolves in a general-purpose solvent, for example, a polyimide resin obtained by reacting an isocyanurate-type polyisocyanate (a1) of an isocyanate having an aliphatic structure with trimellitic anhydride is disclosed (for example, Patent Documents). 1). However, the cured product obtained by using the polyimide resin disclosed in Patent Document 1 has transparency such as insufficient light transmittance particularly in the ultraviolet region (around 300 nm) in light transmittance measurement. Is not enough.

JP 2001-316469 A

An object of the present invention is a curable resin composition that is soluble in a general-purpose solvent and that can provide a cured product (cured coating film) that has high light transmittance from the visible region to the ultraviolet region near 300 nm, and is preferable for this preparation. The object is to provide a polyimide resin that can be used.

As a result of intensive studies, the present inventors have obtained a polyimide resin obtained by using a tricarboxylic acid anhydride having an aliphatic structure in place of the tricarboxylic acid anhydride having an aromatic structure such as trimellitic anhydride in Patent Document 1. As a result, it was found that a curable resin composition capable of obtaining a cured coating film that is soluble in a general-purpose solvent and excellent in heat resistance and light transmittance was obtained, and the present invention was completed.

That is, the present invention provides a polyimide resin obtained by reacting an isocyanurate type polyisocyanate (a1) synthesized from an isocyanate having an aliphatic structure and a tricarboxylic acid anhydride (a2) having an aliphatic structure. It is.

Moreover, this invention provides the curable resin composition characterized by containing a polyimide resin (A) and an epoxy resin (B) which has a 2 or more epoxy group in a molecule | numerator first term. .

Furthermore, the present invention provides a cured product obtained by curing the curable resin composition.

The curable resin composition obtained by using the polyimide resin of the present invention is soluble in a general-purpose solvent and provides a cured coating film having excellent heat resistance and light transmittance. It can be suitably used in fields where transparency of the cured product is required. In addition, in fields where transparency of cured products is not required, such as various heat-resistant coating materials and electrical insulating materials, such as interlayer insulating materials for printed wiring boards, build-up materials, semiconductor passivation films, gate insulating films, protection It can also be suitably used in the fields of membranes and insulating materials, batteries such as lithium ion batteries, conductive films, and heat-resistant adhesives.

The polyimide resin of the present invention is obtained by reacting an isocyanurate type polyisocyanate (a1) synthesized from an isocyanate having an aliphatic structure with a tricarboxylic acid anhydride (a2) having an aliphatic structure.

Examples of the isocyanurate type polyisocyanate (a1) synthesized from an isocyanate having an aliphatic structure include an isocyanurate type polyisocyanate synthesized from an isocyanate having a linear aliphatic structure and an isocyanate having a cyclic aliphatic structure. Examples include synthesized isocyanurate type polyisocyanates.

Examples of the isocyanurate type polyisocyanate synthesized from an isocyanate having a linear aliphatic structure include HDI3N (isocyanurate type triisocyanate synthesized from hexamethylene diisocyanate (including polymers such as pentamers)), HTMDI3N, and the like. (Isocyanurate-type triisocyanate synthesized from trimethylhexamethylene diisocyanate (including polymers such as pentamers)) and the like. These may be used in combination or alone.

Examples of the isocyanurate type polyisocyanate synthesized from an isocyanate having a cycloaliphatic structure include IPDI3N (isocyanurate type triisocyanate synthesized from isophorone diisocyanate (including polymers such as pentamers)), HTDI3N ( Isocyanurate type triisocyanate (including polymer such as pentamer) synthesized from hydrogenated tolylene diisocyanate, HXDI3N (Isocyanurate type triisocyanate synthesized from hydrogenated xylene diisocyanate (polymer such as pentamer) ), NBDI3N (isocyanurate-type triisocyanate synthesized from norbornane diisocyanate (including polymers such as pentamers)), HMDI3N (isocyanur synthesized from hydrogenated diphenylmethane diisocyanate) Chromatography (including 5-mers, etc. of the polymer) preparative triisocyanate), and the like.

The isocyanurate type polyisocyanate (a1) synthesized from an isocyanate having an aliphatic structure used in the present invention has a cycloaliphatic structure because a cured coating film having a particularly high Tg and excellent thermal properties can be obtained. Isocyanurate type polyisocyanate synthesized from isocyanate is preferable, and isocyanurate type triisocyanate synthesized from isophorone diisocyanate is particularly preferable. The isocyanurate type triisocyanate synthesized from isophorone diisocyanate may contain a polymer such as a pentamer.

The isocyanurate type polyisocyanate synthesized from an isocyanate having a cyclic aliphatic structure in the isocyanurate type polyisocyanate (a1) synthesized from an isocyanate having an aliphatic structure is based on the weight of the compound (a1). 50 to 80% by weight is preferable because a cured coating film having a high Tg and excellent thermal properties can be obtained, more preferably 80 to 100% by weight, and most preferably 100% by weight.

In addition, an adduct obtained by urethanization reaction of the isocyanate compound and various polyols can be used as long as the solvent solubility of the polyimide resin of the present invention is not impaired.

The carboxy group-containing imide resin (A) used in the present invention has a problem in stability and the like by directly forming an imide bond from the above-described isocyanate compound (a1) and the tricarboxylic acid anhydride (a2) having an aliphatic structure. Without passing through a certain polyamic acid intermediate, a polyimide resin having good reproducibility, good solubility and excellent transparency can be synthesized.

In the present invention, the transparency of the polyimide resin obtained by using a tricarboxylic acid anhydride (a2) having an aliphatic structure as a raw material for polyimide is improved. Examples of the tricarboxylic acid anhydride having an aliphatic structure include a tricarboxylic acid anhydride having a linear aliphatic structure, a tricarboxylic acid anhydride having a cyclic aliphatic structure, and the like. Examples of the tricarboxylic acid anhydride having a linear aliphatic structure include propane tricarboxylic acid anhydride. Examples of the tricarboxylic acid anhydride having a cycloaliphatic structure include cyclohexanetricarboxylic acid anhydride, methylcyclohexanetricarboxylic acid anhydride, cyclohexentricarboxylic acid anhydride, methylcyclohexentricarboxylic acid anhydride, and the like.

Among the tricarboxylic acid anhydrides (a2) having an aliphatic structure used in the present invention, in addition to transparency, a cured coating film having a high Tg and excellent thermal properties can be obtained, so that a tricarboxylic acid anhydride having a cyclic aliphatic structure is obtained. Things are preferred. Examples of the tricarboxylic acid anhydride having a cycloaliphatic structure include cyclohexane tricarboxylic acid anhydride. One or more of these can be used. In some cases, bifunctional dicarboxylic acid compounds such as adipic acid, sebacic acid, phthalic acid, fumaric acid, maleic acid and acid anhydrides thereof may be used in combination.

Examples of the cyclohexanetricarboxylic acid anhydride include cyclohexane-1,3,4-tricarboxylic acid-3,4-anhydride, cyclohexane-1,3,5-tricarboxylic acid-3,5-anhydride, cyclohexane-1 2,3-tricarboxylic acid-2,3-anhydride and the like. Among these, cyclohexane-1,3,4-tricarboxylic acid-3,4-anhydride is obtained because it becomes a polyimide resin having excellent solvent solubility in addition to transparency, and a cured coating film having a high Tg and excellent thermal properties can be obtained. preferable.

Here, the above-mentioned cyclohexanetricarboxylic acid anhydride is represented by the structure of the following general formula (1), and cyclohexane-1,2,3-tricarboxylic acid, cyclohexane-1,3,4, which is used as a production raw material. -In the range where impurities such as tricarboxylic acid do not impair the curing of the present invention, for example, 10% by weight or less, preferably 5% by weight or less, they may be mixed.

When the carboxylic acid component of the tricarboxylic acid anhydride (a2) reacts with the isocyanate component in the polyisocyanate (a1), an imide and an amide are formed, and the polyimide resin of the present invention becomes an imidoamide resin. Further, when the polyisocyanate (a1) is reacted with the tricarboxylic acid anhydride (a2) having an aliphatic structure, the tricarboxylic acid anhydride (a2) is left in such a ratio as to leave the carboxylic acid component of the tricarboxylic acid anhydride (a2). ) And polyisocyanate (a1) are reacted, the resulting polyimide resin has a carboxy group. This carboxy group reacts with the epoxy group of the epoxy resin contained in the curable resin composition of the present invention described later to form a crosslinked structure of the cured product. Since the reaction rate is fast imidization, even in the reaction of tricarboxylic acid and triisocyanate, tricarboxylic acid selectively forms an imide at the acid anhydride.

When the isocyanurate type polyisocyanate (a1) synthesized from the isocyanate having an aliphatic structure is reacted with the tricarboxylic acid anhydride (a2) having an aliphatic structure to obtain the polyimide resin (A) of the present invention. The reaction is preferably carried out in a polar solvent that does not contain any nitrogen atom or sulfur atom. In the presence of a polar solvent containing nitrogen or sulfur atoms, environmental problems are likely to occur, and in the reaction of isocyanurate type polyisocyanate (a1) with tricarboxylic acid anhydride (a2), molecular growth occurs. Is likely to be disturbed. When such a molecule is cut, the physical properties of the composition are likely to deteriorate, and film defects such as “repellency” tend to occur.

In the present invention, the polar solvent containing neither a nitrogen atom nor a sulfur atom is more preferably an aprotic solvent. For example, a cresol solvent is a phenolic solvent having protons, but is somewhat unfavorable in terms of the environment, and easily reacts with an isocyanate compound to hinder molecular growth. In addition, the cresol solvent easily reacts with an isocyanate group to easily become a blocking agent. Therefore, it is difficult to obtain good physical properties by reacting with other curing components (for example, epoxy resin) during curing. Furthermore, if the blocking agent is removed, it is likely to cause contamination of the equipment used and other materials. Also, alcohol solvents are not preferred because they react with isocyanates or acid anhydrides. Examples of the aprotic solvent include ether-based, ester-based, and ketone-based solvents having no hydroxyl group, and among these, ether-based solvents having no hydroxyl group are particularly preferable.

In the present invention, the polar solvent containing neither a nitrogen atom nor a sulfur atom is more preferably an ether solvent. The ether solvent has a weak polarity and has an excellent reaction field in the reaction of the above-mentioned isocyanate isocyanurate type polyisocyanate (a1) having an aliphatic structure and the tricarboxylic acid anhydride (a2) having an aliphatic structure. provide. As such ether solvents, known and commonly used solvents can be used. For example, ethylene glycol dialkyl ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether; diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether , Polyethylene glycol dialkyl ethers such as triethylene glycol dimethyl ether, triethylene glycol diethyl ether and triethylene glycol dibutyl ether; ethylene glycol monomers such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate and ethylene glycol monobutyl ether acetate Alkyl ether acetates; polyethylene glycol monoalkyl ether acetates such as diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, triethylene glycol monomethyl ether acetate, triethylene glycol monoethyl ether acetate, triethylene glycol monobutyl ether acetate Propylene glycol dialkyl ethers such as propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol dibutyl ether; dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, dipropylene glycol dibutyl ether Polypropylene glycol dialkyl ethers such as tellurium, tripropylene glycol dimethyl ether, tripropylene glycol diethyl ether, tripropylene glycol dibutyl ether; propylene glycol monoalkyl such as propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monobutyl ether acetate Ether acetates: Dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate, dipropylene glycol monobutyl ether acetate, tripropylene glycol monomethyl ether acetate, tripropylene glycol monoethyl ether acetate, tripropylene group Polypropylene glycol monoalkyl ether acetates such as recall monobutyl ether acetate; or dialkyl ethers of copolymerized polyether glycols such as low molecular weight ethylene-propylene copolymers; monoacetate monoalkyl ethers of copolymerized polyether glycols; or Such polyether glycol alkyl esters; polyether glycol monoalkyl esters monoalkyl ethers, and the like.

The isocyanurate type polyisocyanate (a1) synthesized from an isocyanate having an aliphatic structure and the tricarboxylic acid anhydride (a2) having an aliphatic structure are an isocyanurate type polyisocyanate synthesized from an isocyanate having an aliphatic structure. The total number of moles of the number of moles (N) of the isocyanate group (a1) and the number of moles (M1) of the carboxy group and the number of moles of acid anhydride (M2) of the tricarboxylic acid anhydride (a2) having an aliphatic structure. The reaction is carried out so that the ratio [(M1) + (M2)) / (N)] is 1.1 to 3, because the polarity in the reaction system becomes high and the reaction proceeds to lubrication. The remaining polyimide resin has good stability, the residual amount of tricarboxylic acid anhydride (a2) is small, and separation problems such as recrystallization hardly occur. It preferred by reason of an equal. Among these, 1.2 to 2 is more preferable. In the present invention, the acid anhydride group refers to a —CO—O—CO— group obtained by intramolecular dehydration condensation of two molecules of carboxylic acid.

The imidization reaction is performed in a solvent or in the absence of a solvent by mixing one or more isocyanate compounds (a1) and one or more tricarboxylic acid anhydrides (a2) and raising the temperature while stirring. Is preferred. The reaction temperature is preferably 50 ° C. to 250 ° C., particularly preferably 70 ° C. to 180 ° C. By setting such a reaction temperature, the reaction rate is increased, and the side reaction and decomposition are less likely to occur. While the reaction is accompanied by decarboxylation, the acid anhydride group and the isocyanate group form an imide group. The progress of the reaction can be followed by an analytical means such as an infrared vector, acid value, or isocyanate group quantification. The infrared spectrum, 2270 cm ^-1 which is the characteristic absorption of an isocyanate group was reduced as the reaction further acid anhydride group is reduced with a characteristic absorption at 1860 cm ^-1 and 850 cm ^-1. On the other hand, the absorption of imide groups increases at 1780 cm ⁻¹ and 1720 cm ⁻¹ . The reaction may be terminated by lowering the temperature while confirming the target acid value, viscosity, molecular weight and the like. However, it is more preferable to continue the reaction until the isocyanate group disappears from the standpoint of stability over time. In addition, during the reaction or after the reaction, a catalyst, an antioxidant, a surfactant, other solvents, and the like may be added as long as the physical properties of the synthesized resin are not impaired.

The acid value of the polyimide resin of the present invention is preferably 70 to 210 KOH mg / g, and particularly preferably 90 to 190 KOH mg / g. When it is 70 to 210 KOHmg / g, it exhibits excellent performance as a cured material.
The polyimide resin of the present invention is preferably a polyimide resin that dissolves in a polar solvent that does not contain any of the nitrogen and sulfur atoms. Examples of such a polyimide resin include a branched polyimide resin having a branched structure and an acid value of the resin of 60 KOHmg / g or more.

The number average molecular weight of the polyimide resin of the present invention is preferably from 1,000 to 20,000, more preferably from 2,000 to 8,000, from the viewpoints of good solubility in a solvent and a cured product having excellent mechanical strength. The molecular weight can be measured by gel permeation chromatography (GPC) or quantitative analysis of the terminal functional group amount.
In the present invention, the number average molecular weight was determined using GPC under the following conditions.
Measuring device: Tosoh Corporation HLC-8120GPC, UV8020
Column: TFKguardcolumnHXL-L, TFKgel (G1000HXL, G2000HXL, G3000HXL, G4000HXL) manufactured by Tosoh Corporation
Detector: RI (differential refractometer) and UV (254 nm)
Measurement conditions: Column temperature 40 ° C
Solvent THF
Flux 1.0ml / min
Standard: Calibration curve prepared with polystyrene standard sample: 0.1% by weight THF solution in terms of resin solid content filtered through microfilter (injection amount: 200 μl)

Examples of the carboxy group-containing imide resin (A) used in the present invention include imide resins represented by the following (formula 2).

(N is a repeating unit of 0-30. Rb is, for example, a structural unit represented by the following structural formula (Formula 3) or (Formula 4).

(R ₂ is, for example, an aliphatic tricarboxylic acid residue that may have a substituent having 6 to 20 carbon atoms.) Rc is, for example, a structural unit represented by the following structural formula (formula 5) is there.

(R ₂ is, for example, the same as described above.)

Rd is, for example, a trivalent organic group represented by the following (formula 6):

Ra represents, for example, a residue of a divalent aliphatic diisocyanate.

The curable resin composition of the present invention comprises the polyimide resin of the present invention (hereinafter referred to as polyimide resin (A)). And a curable resin (B). For example, the thermosetting resin composition which contains the epoxy compound (B1) component which has a 2 or more epoxy group in a molecule | numerator is mention | raise | lifted. As the component (B1), known and commonly used epoxy resins can be used, and two or more kinds may be mixed and used.
Other examples include melamine resins, isocyanate compounds, silicates and alkoxysilane compounds, (meth) acrylic resins, etc., which are excellent in heat resistance, dimensional stability and mechanical properties (toughness, flexibility). An epoxy resin is preferable in that a cured product such as a cured coating film is obtained.
In addition, the meaning of the above-mentioned and below-mentioned hardened | cured material property described in this invention does not react with the polyimide resin of this invention alone or the polyimide resin of this invention other than the hardened | cured material of the polyimide resin of this invention and the component which reacts with this. It also includes meanings including simply solvent-dried coatings and molded articles that contain other resins, additives, inorganic material components, and the like. Furthermore, the cured product obtained by mixing the polyimide resin of the present invention with a curing agent that reacts by heating or light and / or does not react with the polyimide resin of the present invention, but is cured by heat, light, etc., as an additive component itself. The physical properties are also included in the meaning.

Examples of such epoxy resins include bisphenol A type epoxy resins, bisphenol S type epoxy resins, bisphenol F type epoxy resins, phenol novolac type epoxy resins, cresol novolac type epoxy resins, and dicyclopentadiene reacted with various phenols. Epoxidized products of various dicyclopentadiene-modified phenolic resins, epoxidized products of 2,2 ′, 6,6′-tetramethylbiphenol, epoxidized products of 4,4′-methylenebis (2,6-dimethylphenol), naphthol and binaphthol Alternatively, an epoxy derived from a naphthalene skeleton such as a novolak modification of naphthol or binaphthol, an aromatic epoxy resin such as an epoxy resin obtained by epoxidizing a phenol resin of a fluorene skeleton, and the like can be given.

Also, aliphatic epoxy resins such as neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, hydrogenated bisphenol A type epoxy resin, hydrogenated bisphenol F type epoxy resin, 3,4-epoxycyclohexylmethyl- 3,4-epoxycyclohexanecarboxylate, bis- (3,4-epoxybicyclohexyl) adipate, 1,2-epoxy-4- (2-oxiranyl) cyclohexane of 2,2-bis (hydroxymethyl) -1-butanol A cycloaliphatic epoxy resin such as an adduct, an epoxy resin containing a polyalkylene glycol chain in the main chain, such as polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, and triglycidyl isocyanurate Heterocycle-containing epoxy resins can be used.

In addition, an epoxy group-containing polymerization resin obtained by polymerizing an unsaturated group of an epoxy compound having a polymerizable unsaturated double bond such as a (meth) acryloyl group or a vinyl group, and other monomers having a polymerizable unsaturated bond Copolymers with can also be used.

Examples of the compound having both (meth) acryloyl group and epoxy group include glycidyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate glycidyl ether, hydroxypropyl (meth) acrylate glycidyl ether, 4-hydroxydibutyl (meth) acrylate glycidyl ether. , 6-hydroxyhexyl (meth) acrylate glycidyl ether, 5-hydroxy-3-methylpentyl (meth) acrylate glycidyl ether, (meth) acrylic acid-3,4-epoxycyclohexyl, lactone modified (meth) acrylic acid-3, 4-epoxycyclohexyl, vinylcyclohexene oxide and the like.

The epoxy resin (B) component having two or more epoxy groups in the molecule in the present invention is particularly preferably a cycloaliphatic epoxy resin. If it is a cycloaliphatic epoxy resin, a cured coating film having a high Tg and excellent thermal properties can be obtained, and a cured product having a high light transmittance in the ultraviolet region (around 300 nm) can be obtained. Among cycloaliphatic epoxy resins, hydrogenated bisphenol A type epoxy resin, 1,2-epoxy-4- (2-oxiranyl) cyclohexane adduct of 2,2-bis (hydroxymethyl) -1-butanol and the like are preferable. .

Such cycloaliphatic epoxy resins can be obtained on the market, and examples thereof include Denacol EX-252 (manufactured by Nagase ChemteX Corporation), EHPE3150, EHPE3150CE (manufactured by Daicel Chemical Industries, Ltd.), and the like.

The amount of the epoxy resin (B) having two or more epoxy groups in the molecule is 6 to 1100 parts by weight with respect to 100 parts by weight of the polyimide resin (A) to obtain a cured product having excellent heat resistance and transparency. Therefore, the amount is preferably 15 to 300 parts by weight.

The polyimide resin (A) and the epoxy resin (B) having two or more epoxy groups in the molecule can be freely blended according to various desired physical properties, but thermal such as Tg. An epoxy resin having a carboxy group-containing imide resin (A) having a mole number n (COOH) of the carboxy group-containing imide resin (A) and two or more epoxy groups in the molecule in terms of the balance between physical properties, mechanical properties, etc. and transparency of the cured coating film. Polyimide resin (A) and epoxy resin (B) in such a range that the ratio [n (EPOXY) / n (COOH)] of the number of moles of epoxy group n (EPOXY) in (B) is 0.3 to 4 Is preferable because Tg is easily obtained as a property of the cured product, a cured product having excellent mechanical properties and the like is obtained, and transparency of the cured product is further improved.

The curable resin composition of the present invention may be mixed with an epoxy-carboxylic acid-based curing catalyst or the like. Such epoxy-carboxylic acid curing catalysts include primary to tertiary amines for promoting the reaction, quaternary ammonium salts, nitrogen compounds such as dicyandiamide and imidazole compounds, TPP (triphenylphosphine). ), Known epoxy curing accelerators such as phosphine compounds such as alkyl-substituted trialkyl phonylphosphine and derivatives thereof, phosphophonium salts thereof, dialkylureas, carboxylic acids, phenols, or methylol group-containing compounds. Etc., and a small amount of these can be used in combination.

The curable resin composition of the present invention can be cured by heating after coating, casting or the like on the object. Thereby, the articles | goods containing the hardened | cured material of the curable resin composition of this invention can be obtained. The curing temperature is preferably 80 ° C. to 300 ° C., particularly preferably 120 ° C. to 250 ° C. Further, step curing at various temperatures may be performed. Alternatively, a sheet-like or film-like composition semi-cured at a temperature of about 50 ° C. to 170 ° C. may be stored and treated at the above-described curing temperature when necessary. The curing reaction between the carboxy group-containing imide resin (A) component and the epoxy resin (B) component having two or more epoxy groups in the molecule is basically a reaction between the carboxy group and the epoxy group. It is possible to obtain a curable resin composition having excellent physical properties and the like by selecting the type, blending ratio, curing conditions, etc. of (A) and an epoxy resin (B) having two or more epoxy groups in the molecule. it can. Various additives such as other solvents, various leveling agents, antifoaming agents, antioxidants, anti-aging agents, ultraviolet absorbers, anti-settling agents, rheology control agents and the like are added to the curable resin composition of the present invention as necessary. Agents, known and conventional fillers such as barium sulfate, silicon oxide, talc, clay, calcium carbonate, silica, colloidal silica, glass, various metal powders, fibrous fillers such as glass fiber, carbon fiber, Kevlar fiber, etc. Or you may mix | blend well-known and usual coloring pigments, such as phthalocyanine blue, phthalocyanine green, a titanium oxide, carbon black, a silica, and other adhesive provision agents. Moreover, it is also possible to mix | blend polymers, such as an acrylic resin, a cellulose resin, a polyvinyl resin, polyphenylene ether, and polyether sulfone, as needed.

Next, the present invention will be described in more detail with reference to examples. Unless otherwise specified, “parts” and “%” are based on weight.

Synthesis Example 1 [Preparation of polyimide resin (A)]
In a flask equipped with a stirrer, a thermometer, and a condenser, 4628 g of EDGA (diethylene glycol monoethyl ether acetate), IPDI3N (isocyanurate type triisocyanate synthesized from isophorone diisocyanate: NCO% = 18.2), 2070 g (3 mol) and cyclohexane- 1,386 g (7 mol) of 1,3,4-tricarboxylic acid-3,4-anhydride was added, and the temperature was raised to 140 ° C. The reaction proceeded with foaming. The reaction was carried out at this temperature for 8 hours. As a result of measuring the characteristic absorption in the infrared spectrum, 2270 cm ^−1, which is the characteristic absorption of the isocyanate group, disappeared completely, and the absorption of the imide group was observed at 1780 cm ⁻¹ and 1720 cm ^−1. confirmed. The acid value was 140 KOHmg / g in terms of solid content, and the molecular weight was a number average molecular weight of 5800 in terms of polystyrene. The concentration of the resin component was 40% by weight. This resin solution is abbreviated as an imide resin (A1) solution.

Synthesis example 2 (same as above)
In a flask equipped with a stirrer, a thermometer and a condenser, 4942 g of PGMAc (propylene glycol monomethyl ether acetate), HDI3N (isocyanurate type triisocyanate synthesized from hexamethylene diisocyanate: NCO% = 24.7) 2040 g (4 mol) and cyclohexane -1,3,4-tricarboxylic acid-3,4-anhydride (1782 g, 9 mol) was added, and the temperature was raised to 140 ° C. The reaction proceeded with foaming. The reaction was carried out at this temperature for 8 hours. As a result of measuring the characteristic absorption in the infrared spectrum, 2270 cm ^−1, which is the characteristic absorption of the isocyanate group, disappeared completely, and the absorption of the imide group was observed at 1780 cm ⁻¹ and 1720 cm ^−1. confirmed. The acid value was 130 KOHmg / g in terms of solid content, and the molecular weight was number average molecular weight 6200 in terms of polystyrene. The concentration of the resin component was 40% by weight. This resin solution is abbreviated as an imide resin (A2) solution.

Comparative Synthesis Example 1
In a flask equipped with a stirrer, thermometer and condenser, 4500 g of EDGA (diethylene glycol monoethyl ether acetate), IPDI3N (isocyanurate type triisocyanate synthesized from isophorone diisocyanate: NCO% = 18.2) and anhydrous tri 1728 g (9 mol) of merit acid was added, and the temperature was raised to 140 ° C. The reaction proceeded with foaming. The reaction was carried out at this temperature for 10 hours. The system became a light brown clear liquid. As a result of measuring the characteristic absorption in the infrared spectrum, 2270 cm ^−1, which is the characteristic absorption of the isocyanate group, completely disappeared, and the absorption of the imide group at 1780 cm ⁻¹ and 1720 cm ^−1. Was confirmed. The acid value was 95 KOHmg / g in terms of solid content, and the molecular weight was 4300 in terms of polystyrene. The resin content was 47% by weight. This resin solution is abbreviated as an imide resin (a1) solution.

Example 1
The curable resin composition 1 of the present invention was prepared according to the formulation shown in Table 1. The appearance of the cured coating film of the thermosetting resin composition 1 and the Tg and light transmittance of the film of the thermosetting resin composition 1 were evaluated according to the following methods. Table 2 shows the appearance of the cured coating film and Tg of the film, and Table 3 shows the evaluation result of the light transmittance.

<Appearance evaluation method>
The thermosetting resin composition 1 was coated on a glass substrate so that the film thickness after curing was 25 to 35 microns. Next, the coated plate was dried with a dryer at 50 ° C. for 30 minutes, then dried at 100 ° C. for 30 minutes, and finally cured at 170 ° C. for 1 hour, and the appearance of the cured coating film was evaluated according to the following criteria.
A: Uniform and no foreign matter is seen.
X: Repelling, irregularities, foreign matter and cracks can be confirmed.

<Method for evaluating Tg of film>
Preparation of test piece for measurement The tincture was coated on the tin substrate so that the film thickness after curing of the thermosetting resin composition 1 was 25 to 35 microns. Next, this coated plate was dried with a dryer at 50 ° C. for 30 minutes, then dried at 100 ° C. for 30 minutes, and finally cured at 170 ° C. for 1 hour to form a cured coating film. After cooling to room temperature, the cured coating film was cut into a predetermined size, isolated from the substrate, and used as a measurement sample.

Method for measuring Tg of film Dynamic viscoelasticity was measured, and the maximum temperature of Tan δ of the obtained spectrum was defined as TG. The dynamic viscoelasticity was measured under the following conditions.
Measuring instrument: Leo Vibron RSA-II (manufactured by Rheometric)
Jig: Pull Chuck spacing: 20 mm
Measurement temperature: 25 ° C to 400 ° C
Measurement frequency: 1HZ
Temperature increase rate: 3 ° C / min

<Evaluation of light transmittance of film>
Preparation of test piece for measurement The tincture was coated on the tin substrate so that the film thickness after curing of the thermosetting resin composition 1 was 25 to 35 microns. Next, this coated plate was dried with a dryer at 50 ° C. for 30 minutes, then dried at 100 ° C. for 30 minutes, and finally cured at 170 ° C. for 1 hour to form a cured coating film. After cooling to room temperature, the cured coating film was cut into a predetermined size, isolated from the substrate, and used as a measurement sample.

Method for Measuring Light Transmittance of Film Light transmittance was measured under the following conditions. The measured value is the light transmittance (%).
Measuring instrument: Spectrophotometer U-2800 (manufactured by Hitachi High-Technologies Corporation)
Measurement wavelength range: 250 nm to 800 nm

Example 2 and Comparative Examples 1 and 2
Thermosetting resin composition 2 and comparative thermosetting resin compositions 1 and 2 were prepared according to the formulation shown in Table 1. Evaluation was performed in the same manner as in Example 1, and the results are shown in Tables 2 and 3.

Footnotes in Table 1 ・ EHPE3150: Cyclic aliphatic epoxy resin (1,2-epoxy-4- (2-oxiranyl) of 2,2-bis (hydroxymethyl) -1-butanol) manufactured by Daicel Chemical Industries, Ltd. Cyclohexane adduct). Epoxy equivalent is 177. The resin content is 100% by weight.
Epicron N-680: Cresol novolac type epoxy resin manufactured by DIC Corporation. The epoxy equivalent is 211. The resin content is 100% by weight.
Denacol EX-252: Cyclic aliphatic epoxy resin (hydrogenated bisphenol A type epoxy resin) manufactured by Nagase ChemteX Corporation. Epoxy equivalent is 212. The resin content is 100% by weight.
・ TPP: Triphenylphosphine

Claims

A polyimide resin obtained by reacting an isocyanurate type polyisocyanate (a1) synthesized from an isocyanate having an aliphatic structure with a tricarboxylic acid anhydride (a2) having an aliphatic structure.
The isocyanurate type polyisocyanate compound (a1) is an isocyanurate type polyisocyanate synthesized from an isocyanate having a cyclic aliphatic structure, and the tricarboxylic acid anhydride (a2) having an aliphatic structure is a tricarboxylic acid having a cyclic aliphatic structure. The polyimide resin according to claim 1, which is an acid anhydride.
The isocyanurate-type polyisocyanate compound having a cycloaliphatic structure is an isocyanurate-type triisocyanate (including polymers such as pentamers) synthesized from isophorone diisocyanate, and a tricarboxylic acid anhydride having a cycloaliphatic structure. The polyimide resin according to claim 2, wherein is cyclohexane-1,3,4-tricarboxylic acid-3,4-anhydride.
The number of moles of isocyanate groups (N) of the isocyanurate type polyisocyanate (a1) synthesized from the isocyanate having an aliphatic structure and the number of moles of carboxy groups of the tricarboxylic acid anhydride (a2) having an aliphatic structure (M1 4. The polyimide resin according to claim 3, wherein the ratio [(M1) + (M2)) / (N)] of the total number of moles of acid anhydride groups (M2) is 1.1 to 3.
The polyimide resin according to claim 4, having an acid value of 70 to 210 KOHmg / g.
The polyimide resin according to any one of claims 1 to 5, which dissolves in a polar solvent containing neither a nitrogen atom nor a sulfur atom.
A curable resin composition comprising the polyimide resin (A) according to any one of claims 1 to 6 and a curable resin (B).
The curable resin composition according to claim 7, wherein the curable resin (B) is an epoxy compound (B1) having two or more epoxy groups in a molecule.
The curable resin composition according to claim 8, wherein the epoxy resin (B) is an epoxy resin having a cycloaliphatic structure.
The curability according to claim 9, wherein the epoxy resin having a cycloaliphatic structure is a 1,2-epoxy-4- (2-oxiranyl) cyclohexane adduct of 2,2-bis (hydroxymethyl) -1-butanol. Resin composition.
The curable resin composition according to claim 8, wherein the content of the epoxy resin (B1) is 6 to 1100 parts by weight with respect to 100 parts by weight of the polyimide resin (A).
A cured product obtained by curing the curable resin composition according to claim 7.