JP5399754B2 - Polyimide resin precursor and cured product thereof - Google Patents

Description

  The present invention relates to a polyimide resin precursor containing a urethane prepolymer having a terminal isocyanate group sealed with a blocking agent, a cured product thereof, and a method for producing the same.

  Polyimide resin is an engineering plastic having high heat resistance and chemical resistance, and as its production method, a diamine is used as a raw material and a two-step reaction process (two-step method) and a diisocyanate is used as a raw material. A method of carrying out the reaction in one step (one-step method) is known. However, since a polyimide resin has low heat melting property and is hardly soluble in a solvent, a two-stage method using an intermediate polyamic acid (polyamic acid) is widely used industrially.

  Specifically, in the two-stage method, a step in which a diamine and an acid anhydride are reacted to form a polyamic acid, and a solution obtained by dissolving the obtained polyamic acid in a solvent is heated to perform dehydration cyclization (thermal imidization). A polyimide resin is obtained through the steps. However, in this method, since the thermal imidization reaction of the polyamic acid is a reaction accompanied by dehydration, the polyamic acid solution is heated stepwise from around 100 ° C. in the thermal imidization step, and water generated by the dehydration cyclization reaction. The heat treatment needs to be performed up to about 350 ° C. while removing the component from the system, and the moldability is low. In addition, since the precursor polyamic acid solution is used, it must be molded simultaneously with the thermal imidization reaction of the polyamic acid solution, and the resulting cured polyimide resin is limited to a thin film or a laminate thereof. ing. Furthermore, the solvent that can be used in the polyamic acid solution is limited to a highly polar compound, and N-methyl-2-pyrrolidone (NMP) is used as a preferred polar solvent. However, such a highly polar solvent is easy to absorb moisture and hydrolyzes the polyamic acid. Therefore, improvement in storage stability of the polyamic acid solution is required.

  On the other hand, even in the one-stage method, studies are being made to improve the properties and moldability of the polyimide resin that is the final product. For example, as an industrially advantageous production method of a polyimide resin, JP-A-8-295734 (Patent Document 1) discloses a diisocyanate compound containing an alicyclic or aromatic ring in which an isocyanate group may be blocked. And a method for producing a polyimide resin by reacting an acid anhydride. In this document, by using an alicyclic or aromatic diisocyanate compound, a polyimide resin that is less colored and highly soluble is industrially advantageously produced. Moreover, it is described that the isocyanate group of a diisocyanate compound may be blocked.

  However, according to the method of this document, the solubility of the polyimide resin in the solvent can be improved, and a film can be produced using the solvent, but a molded body having a thick or complicated shape cannot be obtained without using the solvent.

  Japanese Patent Application Laid-Open No. 2008-13635 (Patent Document 2) discloses a heat-resistant resin varnish containing a polyamideimide resin and a polyamic acid in which molecular terminal isocyanate functional groups are sealed with a blocking agent. In this document, as a polyamideimide resin, a polyamideimide obtained by reacting a tricarboxylic acid anhydride and a polyvalent isocyanate, or a polycarboxylic acid is reacted with a tricarboxylic acid anhydride and a polyvalent amine to form an imide bond, and then a polyvalent isocyanate is used. A polyamideimide that has been reacted and amidated is described, and aminophenylfluorene is exemplified as an example of the polyvalent amine. Furthermore, it is described that the viscosity of the mixture with the polyamic acid can be suppressed (gelation) by sealing the isocyanate group of the polyamideimide with a blocking agent. However, even in this document, a molded body of polyimide resin is not obtained.

  On the other hand, JP-A-2005-220340 (Patent Document 3) discloses a polyurethaneimide resin composed of a block copolymer in which a polyurethane oligomer obtained from a diisocyanate and a diol is chain-extended with a tetracarboxylic dianhydride. Has been. However, also in this document, the polyurethaneimide resin is prepared as an adhesive composition, and a molded product is not obtained.

  Furthermore, in any of Patent Documents 1 to 3, the heat resistance is lowered by improving the moldability and workability of the polyimide resin.

JP-A-8-295734 (claim 4, paragraphs [0020] [0021], examples) JP 2008-13635 A (Claim 1, paragraphs [0008] [0010] [0018]) Japanese Patent Laying-Open No. 2005-220340 (Claims and Examples)

  Therefore, the objective of this invention is providing the polyimide precursor which can improve a moldability, a handleability, and storage stability, its hardened | cured material (polyimide), and its manufacturing method.

  Another object of the present invention is to provide a polyimide precursor, a cured product thereof, and a method for producing the same that can easily form a thick molded article at a low temperature and in a short time without using a solvent.

  Still another object of the present invention is to provide a polyimide molded body having high mechanical properties such as toughness, heat resistance and chemical resistance, and a method for producing the same.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors have combined moldability, handleability and storage stability by combining a urethane prepolymer having a terminal isocyanate group sealed with a blocking agent and an acid anhydride. The present invention has been completed.

  That is, the curable resin composition of the present invention includes a urethane prepolymer (A) having a terminal isocyanate group sealed with a blocking agent and an acid anhydride (B). The urethane prepolymer (A) may be a prepolymer in which a reaction product of a diol represented by the following formula (1) and a diisocyanate is end-capped with ketoximes.

(In the formula, ring Ar represents an aromatic hydrocarbon ring, R ¹ represents a cyano group, a halogen atom or a hydrocarbon group, R ² represents a hydrocarbon group, an alkoxy group, a cycloalkoxy group, an aryloxy group, an aralkyloxy group. , An alkylthio group, a cycloalkylthio group, an arylthio group, an aralkylthio group, an acyl group, a halogen atom, a nitro group, a cyano group or a substituted amino group, A ¹ represents an alkylene group, k is an integer of 0 to 4, m And n is an integer of 0 or more).

  The diisocyanate may be an aromatic diisocyanate. The acid anhydride may be an aromatic tetracarboxylic dianhydride. The equivalent ratio of the end-capped isocyanate group of the urethane prepolymer (A) and the acid anhydride group of the acid anhydride (B) is about the former / the latter = 1/1 to 1 / 1.8.

  The present invention includes a method for producing a polyimide molded body by heating the curable resin composition. Since this resin composition is excellent in handleability as a mixture (compound), it is not necessary to dissolve in a solvent. Therefore, in the said manufacturing method, a polyimide molded body is obtained by heating at 180-300 degreeC, without using a solvent. Further, the present invention includes a polyimide molded body obtained by the above method.

  In the present invention, since the urethane prepolymer having a terminal isocyanate group sealed with a blocking agent and an acid anhydride are combined, the moldability, handleability and storage stability can be improved. Moreover, a thick polyimide molded body can be simply molded at a low temperature and in a short time without using a solvent. Furthermore, a polyimide molded body having high mechanical properties such as toughness, heat resistance and chemical resistance can be obtained.

[Curable resin composition]
The curable resin composition (polyimide precursor) of the present invention includes a urethane prepolymer (A) having a terminal isocyanate group sealed with a blocking agent and an acid anhydride (B).

(A) Urethane prepolymer The urethane prepolymer (A) is obtained by sealing a urethane prepolymer having a terminal isocyanate group with a blocking agent. In the present invention, the storage stability of the resin composition can be improved by sealing the terminal isocyanate group of the urethane prepolymer with a blocking agent.

  Such a urethane prepolymer (A) is not particularly limited as long as it has a urethane skeleton and has an isocyanate group at the terminal, and is usually obtained by reacting an excess amount of polyisocyanates with polyols. .

(Polyisocyanates)
The polyisocyanate is not particularly limited as long as it has two or more isocyanate groups in the molecule, and examples thereof include aliphatic polyisocyanates, alicyclic polyisocyanates, araliphatic polyisocyanates, aromatic polyisocyanates, and polyisocyanates. Derivatives and the like.

Examples of the aliphatic polyisocyanate include diisocyanates (for example, C _2-16 alkane diisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, 2 , 6-diisocyanatomethylcaproate), polyisocyanates having 3 or more isocyanate groups in the molecule (for example, C _6-20 alkane triisocyanate such as lysine ester triisocyanate) and the like.

  Examples of the alicyclic polyisocyanates include diisocyanates (for example, 1,4-cyclohexane diisocyanate, isophorone diisocyanate (IPDI), 4,4′-methylenebis (cyclohexyl isocyanate), hydrogenated xylylene diisocyanate, norbornane diisocyanate, etc.) And a polyisocyanate having three or more isocyanate groups (for example, 1,3,5-trimethylisocyanatocyclohexane, 2- (3-isocyanatopropyl) -2,5-di (isocyanatomethyl) -bicyclo [2. 2.1] heptane, 5- (2-isocyanatoethyl) -2-isocyanatomethyl-3- (3-isocyanatopropyl) -bicyclo [2.2.1] heptane, and the like. It is done.

  Examples of the araliphatic polyisocyanate include diisocyanates [for example, xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate, etc.], polyisocyanates having three or more isocyanate groups in the molecule (for example, 1,3,5- And triisocyanates such as triisocyanatomethylbenzene).

  Examples of the aromatic polyisocyanate include diisocyanates (for example, phenylene diisocyanate, 1,5-naphthylene diisocyanate (NDI), diphenylmethane diisocyanate (MDI), tolylene diisocyanate (TDI), 4,4′-toluidine diisocyanate, 4,4. '-Diphenyl ether diisocyanate, etc.), polyisocyanates having 3 or more isocyanate groups in the molecule (for example, triisocyanates such as triphenylmethane-4,4', 4 ''-triisocyanate, for example, 4,4'- And tetraisocyanates such as diphenylmethane-2,2 ′, 5,5′-tetraisocyanate).

  Examples of the polyisocyanate derivatives include dimer, trimer, biuret, allophanate of polyisocyanate, and polyisocyanate having 2,4,6-oxadiazinetrione ring, which is a polymer of carbon dioxide and the above polyisocyanate monomer. Isocyanates, carbodiimides, uretdiones and the like.

  These polyisocyanates may be used alone or in combination of two or more. Of these polyisocyanates, aliphatic diisocyanates such as HDI, alicyclic diisocyanates such as IPDI and hydrogenated XDI, araliphatic diisocyanates such as XDI, and aromatic diisocyanates such as TDI, MDI and NDI are widely used and heat resistant. From the viewpoint of properties and mechanical strength, aromatic diisocyanates such as MDI and NDI are particularly preferred.

(Polyols)
Examples of the polyols include aliphatic diol [alkanediol (ethylene glycol, propylene glycol, trimethylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 1,5-pentanediol, neopentyl glycol, C _2-22 alkanediol such as 1,6-hexanediol)], alicyclic diols (cycloalkanediols such as 1,4-cyclohexanediol and 1,4-cyclohexanedimethanol, hydrogenated bisphenol A, etc.) hydrogenated bisphenols, or the like of these C _2-4 alkylene oxide adduct), araliphatic diols and aromatic diols (xylylene glycol, bisphenol a, bisphenol S, bisphenol such as bisphenol F, or C _2-4 alkylene oxide adducts of these diols, such as such as diols containing a fluorene skeleton), triols (glycerol, trimethylolethane, trimethylolpropane, 1,2,6-hexanetriol, triethanolamine Amines), tetraols (such as pentaerythritol, sorbitan, or derivatives thereof)], polymer polyols, and the like.

  The polymer polyols include polyester polyols, polyether polyols, polyether ester polyols, polycarbonate polyols, polyester amide polyols, polymer polyols such as acrylic polymer polyols, and the like.

  The polyester polyol may be, for example, a reaction product of a polycarboxylic acid (or its anhydride) and a polyol, or a reaction product obtained by ring-opening addition polymerization of a lactone with respect to an initiator.

Polycarboxylic acids include dicarboxylic acids [for example, aromatic dicarboxylic acids or anhydrides thereof (terephthalic acid, isophthalic acid, phthalic anhydride, etc.), alicyclic dicarboxylic acids or anhydrides thereof (tetrahydrophthalic anhydride, het anhydride, etc. , Hymic anhydride, etc.), aliphatic dicarboxylic acid or its anhydride (succinic acid, succinic anhydride, adipic acid, azelaic acid, sebacic acid and other C _4-20 alkanedicarboxylic acid, maleic anhydride, fumaric acid etc. Saturated dicarboxylic acid etc.)], polyvalent carboxylic acids (for example, trimellitic acid, trimellitic anhydride, pyromellitic anhydride, etc.) or alkyl esters of these carboxylic acids. Of these polycarboxylic acids, aliphatic dicarboxylic acids or anhydrides thereof (C _6-20 alkane dicarboxylic acids such as adipic acid, azelaic acid, sebacic acid, etc. are preferred.

Examples of lactones include C _3-10 lactones such as butyrolactone, valerolactone, caprolactone, and enanthlactone (7-hydroxyheptanoic acid lactone).

  Examples of the polyether polyol include a ring-opening polymer of the oxirane compound (for example, polytetramethylene ether glycol).

  Examples of the polyether ester polyol include a polyether which is a polymer of the dicarboxylic acid (aromatic dicarboxylic acid, alicyclic dicarboxylic acid, aliphatic dicarboxylic acid, etc.) or a dialkyl ester thereof and the polyether polyol. Examples include ester polyols.

  Examples of the polycarbonate polyol include glycols (alkane diols such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol; diethylene glycol, dipropylene glycol). (Poly) oxyalkylene glycols such as: 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, hydrogenated bisphenol A and other alicyclic diols; bisphenols such as bisphenol A, alkylene oxide adducts of bisphenols, etc. One or more glycols selected from aromatic diols) and carbonates (dimethyl carbonate, ethylene carbonate, diphenyl carbonate, etc.) or phosgene And the like polymers and the like.

  As the polyesteramide polyol, in the reaction of the polyester polyol (polymerization of dicarboxylic acid and diol, etc.), a terminal carboxyl group-containing polyester and a diamine (for example, an aliphatic group having an amino group such as ethylenediamine, propylenediamine, hexamethylenediamine, etc.) And polyester amide polyol having a diamine as a reaction component.

  As the acrylic polyol, a polymerizable monomer having a hydroxyl group (for example, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, etc.) and a hydroxyl group-free (meth) An acrylic polyol which is a polymer with an acrylic monomer (for example, (meth) acrylic acid or an ester thereof) may be used.

  These polyols can be used individually or in combination of 2 or more types. Of these polyols, aromatic diols, particularly diols having a fluorene skeleton are preferred from the viewpoint of mechanical properties and heat resistance. By using a diol having a fluorene skeleton, moldability and workability can be improved without reducing the heat resistance of polyimide as an engineering plastic. Furthermore, mechanical properties such as toughness and chemical resistance can be improved.

(Diol having a fluorene skeleton)
The diol having a fluorene skeleton may be a diol represented by the following formula (1).

(In the formula, Ar represents an aromatic hydrocarbon ring, R ¹ represents a cyano group, a halogen atom or a hydrocarbon group, R ² represents a hydrocarbon group, an alkoxy group, a cycloalkoxy group, an aryloxy group, an aralkyloxy group. , An alkylthio group, a cycloalkylthio group, an arylthio group, an aralkylthio group, an acyl group, a halogen atom, a nitro group, a cyano group or a substituted amino group, A ¹ represents an alkylene group, k is an integer of 0 to 4, m And n is an integer of 0 or more).

In the formula (1), examples of the aromatic hydrocarbon ring represented by the ring Ar include a benzene ring and a condensed polycyclic aromatic hydrocarbon ring (specifically, a condensed polycyclic hydrocarbon ring containing at least a benzene ring). ) And the like. As the condensed polycyclic aromatic hydrocarbon ring, a condensed bicyclic hydrocarbon ring (for example, a C _8-20 condensed bicyclic hydrocarbon ring such as an indene ring or a naphthalene ring, preferably a C _10-16 condensed bicyclic ring) And condensed bicyclic hydrocarbon rings such as an anthracene ring and a phenanthrene ring. Preferred examples of the condensed polycyclic aromatic hydrocarbon ring include a naphthalene ring and an anthracene ring, and a naphthalene ring is particularly preferable. The two rings Ar substituted at the 9-position of fluorene may be the same or different rings, and may usually be the same ring.

  Preferred rings Ar include a benzene ring and a naphthalene ring. In addition, when the ring Ar is a condensed polycyclic aromatic hydrocarbon ring, the substitution position of the ring Ar substituted at the 9th position of fluorene is not particularly limited. For example, the naphthyl group substituted at the 9th position of fluorene is , 1-naphthyl group, 2-naphthyl group and the like.

In the formula (1), examples of the substituent represented by the group R ¹ include a cyano group, a halogen atom (fluorine atom, chlorine atom, bromine atom, etc.), a hydrocarbon group [eg, alkyl group, aryl Group (C _6-10 aryl group such as phenyl group) and the like] and the like, and in particular, a cyano group or an alkyl group (particularly an alkyl group) in many cases. Examples of the alkyl group include C _1-6 alkyl groups such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, and a t-butyl group (for example, a C _1-4 alkyl group, particularly a methyl group). . In addition, when k is plural (two or more), the groups R ¹ may be different from each other or the same. Further, the groups R ¹ substituted on the two benzene rings constituting the fluorene (or fluorene skeleton) may be the same or different. Further, the bonding position (substitution position) of the group R ¹ with respect to the benzene ring constituting the fluorene is not particularly limited. The preferred substitution number k is 0 to 1, in particular 0. In the two benzene rings constituting fluorene, the number of substitutions k may be the same or different from each other.

In the formula (1), examples of the substituent represented by R ² include an alkyl group (for example, methyl group, ethyl group, propyl group, isopropyl group, butyl group, s-butyl group, t-butyl group). A C _1-20 alkyl group such as a group), a cycloalkyl group (such as a C _5-10 cycloalkyl group such as a cyclopentyl group or a cyclohexyl group), an aryl group [eg, a phenyl group, an alkylphenyl group (a methylphenyl group) (Or C _6-10 aryl group such as naphthyl group), aralkyl group (benzyl group, phenethyl group, etc.) (or tolyl group, 2-methylphenyl group, 3-methylphenyl group, etc.), dimethylphenyl group (xylyl group, etc.) _{C 6-10} an aryl _{-C 1-4} alkyl group) hydrocarbon group such as and the like; alkoxy group (methoxy group, an ethoxy group, Pro Alkoxy groups, such as _{C 1-20} alkoxy group such as butoxy), such as _{C 5-10} cycloalkyl group such as a cycloalkoxy group (hexyloxy group cyclohexylene), _{C 6-10} aryl, such as aryloxy group (phenoxy group An oxy group), an ether group such as an aralkyloxy group (for example, a C _6-10 aryl-C _1-4 alkyloxy group such as a benzyloxy group); an alkylthio group (methylthio group, ethylthio group, propylthio group, n-butylthio group) C _1-20 alkylthio group such as t-butylthio group), cycloalkylthio group (such as C _5-10 cycloalkylthio group such as cyclohexylthio group), arylthio group (C _6-10 arylthio group such as thiophenoxy group) ), aralkylthio group (eg, _C, such as benzylthio _{6- C 1-6} acyl group such as an acyl group (acetyl group); ₀ aryl _{-C 1-4} thioether group, such as an alkylthio group) halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom); nitro group A cyano group; a substituted amino group (such as a dialkylamino group);

Of these, the group R ² is preferably a hydrocarbon group, an alkoxy group, a cycloalkoxy group, an aryloxy group, an aralkyloxy group, an acyl group, a halogen atom, a nitro group, a cyano group, or a substituted amino group, The preferred group R ² is a hydrocarbon group [eg, alkyl group (eg, C _1-6 alkyl group)], alkoxy group (eg, C _1-4 alkoxy group), halogen atom (fluorine atom, chlorine atom, bromine). Atoms, iodine atoms, etc.). In particular, when the ring Ar is a benzene ring, the group R ² may be a group selected from a C _1-4 alkyl group, an aryl group and a halogen atom.

In the same ring Ar, when m is plural (two or more), the groups R ² may be different from each other or the same. In the two rings Ar, the groups R ² may be the same or different. The substitution position of the group R ² is not particularly limited. For example, when the ring Ar is a benzene ring, the substitution is performed at an appropriate position (for example, the 3rd, 3rd, 5th position, etc.) of the 2-6 position of the phenyl group. It may be.

  The preferred substitution number m may be 0 to 8, preferably 0 to 6 (for example, 1 to 5), more preferably 0 to 4, particularly 0 to 2 (for example, 0 to 1). In particular, when the ring Ar is a benzene ring, the preferred substitution number m may be 0 to 4, preferably 0 to 3, and more preferably 0 to 2. In the two rings Ar, the number of substitutions m may be the same or different from each other.

In the formula (1), the group A ¹ is an alkylene group. Examples of the alkylene group include linear or branched C _2-10 alkylene groups such as an ethylene group, a propylene group, a propylidene group, a trimethylene group, and a tetramethylene group. Of these, C _2-4 alkylene groups such as ethylene group and propylene group are preferred.

  The repeating number n of the oxyalkylene group is an integer of 0 or more, usually about 0 to 10, preferably 0 to 5, more preferably about 0 to 3 (particularly 0 to 2). Furthermore, the repeating number n of the oxyalkylene group is usually 1.

Representative diols represented by formula (1) include, for example, 9,9-bis (hydroxy (poly) alkoxyphenyl) fluorene {for example, 9,9-bis [4- (2-hydroxyethoxy) phenyl]. 9,9-bis (hydroxy (poly) C _2-4 alkoxyphenyl) fluorene and the like} such as fluorene}, 9,9-bis (alkyl-hydroxy (poly) alkoxyphenyl) fluorene [eg, 9,9-bis [4 9,9-bis (mono or di-C) such as-(2-hydroxyethoxy) -3-methylphenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3,5-dimethylphenyl] fluorene _4alkyl - hydroxy _{(poly) C 2-4} alkoxyphenyl) fluorene, etc.], 9,9-bis (aryl - hydroxy (poly) Turkey hydroxyphenyl) fluorene [e.g., 9,9-bis [4- (2-hydroxyethoxy) -3-phenylphenyl] fluorene such as 9,9-bis (mono- or _{di-C 6-8} aryl - hydroxy (poly) C _2-4 alkoxy-phenyl) fluorene and the like], 9,9-bis (hydroxy (poly) alkoxynaphthyl) fluorene [eg, 9,9-bis [1- (6- (2-hydroxyethoxy) naphthyl)] fluorene 9,9-bis (hydroxy (poly) C _2-4 alkoxynaphthyl) fluorene etc.] and the like.

(A) Method for Producing Urethane Prepolymer The urethane prepolymer (A) reacts the polyisocyanate with the polyol to produce a prepolymer having a terminal isocyanate group, and then seals the isocyanate group with a blocking agent. It can be manufactured by stopping.

  In the reaction of the polyisocyanate with the polyol, the polyisocyanate is used in an excess amount with respect to the polyol. For example, the isocyanate group of the polyisocyanate is used per 1 mol of the hydroxyl group of the polyol. Is 0.7 mol or more (for example, 0.8 to 5 mol), preferably 1 to 4 mol (for example, 1.5 to 3.5 mol), more preferably 1.8 to 3 mol (particularly 1.9). In general, the isocyanate group of the polyisocyanate is used at a ratio of about 2 mol (1.8 to 2.2 mol) with respect to 1 mol of the hydroxyl group of the polyol.

  You may perform reaction of polyisocyanate and polyols in a solvent. The solvent is not particularly limited as long as it is inert or non-reactive with respect to polyisocyanates and polyols. For example, ethers (for example, dialkyl ethers such as diethyl ether and dipropyl ether, 1, Cyclic ethers such as 4-dioxane, dioxolane, and tetrahydrofuran), ketones (eg, dialkyl ketones such as acetone, methyl ethyl ketone, diisopropyl ketone, and isobutyl methyl ketone), esters (eg, methyl acetate, ethyl acetate, butyl acetate, etc.) Acetates), N-substituted pyrrolidones (N-methyl-2-pyrrolidone, N-methyl-3-pyrrolidone, etc.), hydrocarbons (for example, aromatic hydrocarbons such as toluene, xylene, ethylbenzene, etc.), Halogen solvents (methyl chloride) , Chloroform, carbon tetrachloride, halogenated hydrocarbons such as tetrachloroethane, etc. trichloroethane), and the like nitriles (such as acetonitrile). These solvents may be used alone or in combination of two or more.

  Moreover, you may perform reaction of polyisocyanate and polyols in presence of a catalyst. Examples of the catalyst include organic tin compounds (for example, tin carboxylates such as tin octylate, dibutyltin diacetate, dibutyltin dioctoate, and dibutyltin dilaurate), metal naphthenates (copper naphthenate, zinc naphthenate, naphthene). Organometallic catalysts such as cobalt acid; tertiary amines [eg, trialkylamines such as triethylamine, chain tertiary amines such as benzyldimethylamine; pyridine, methylpyridine, N, N-dimethylpiperazine, tri Cyclic tertiary amines such as ethylenediamine] and the like. These catalysts may be used alone or in combination of two or more.

  The amount of the catalyst used is, for example, 0.001 to 3 parts by weight, preferably 0.005 to 2 parts by weight, more preferably 0.01 to 2 parts by weight with respect to 100 parts by weight of the total amount of polyisocyanates and polyols. It may be about 1 part by weight (for example, 0.02 to 0.5 part by weight). The amount of the catalyst used may be about 0.005 to 5 parts by weight, preferably about 0.01 to 1 part by weight based on 100 parts by weight of the diol.

  The reaction between the polyisocyanate and the polyol may be performed at room temperature or may be performed under heating (for example, about 0 to 100 ° C., preferably 20 to 80 ° C., more preferably about 23 to 50 ° C.). Good. Note that the reaction may be performed in an inert atmosphere (an atmosphere of nitrogen, helium, argon, or the like).

(Block agent)
Although the obtained urethane prepolymer may be separated prior to the reaction with the blocking agent, the reaction is usually carried out by mixing the blocking agent directly into the reaction system containing the urethane prepolymer.

Examples of the blocking agent include conventional isocyanate group blocking agents such as alcohols (eg, C _1-10 alkanols such as methanol, ethanol, propanol, isopropanol, butanol, pentanol, hexanol, etc.), phenols (eg, phenols). , Cresol, xylenol, naphthol, etc.), lactams (for example, C _4-20 lactam such as propiolactam, butyrolactam, valerolactam, caprolactam, caprolactam, capryllactam, enantolactam, undecanolactam, dodecanolactam), Oximes (eg, acetoxime, methyl ethyl ketoxime (2-butanone oxime), methyl propyl ketoxime, methyl butyl ketoxime, methyl propyl ketoxime Methyl (iso) butyl ketoxime, methyl isopentyl ketoxime, diethyl ketoxime, ethyl propyl ketoxime, ethyl butyl ketoxime, diisopropyl ketoxime, such as C _3-10 dialkyl ketoxime such as diisobutyl ketoxime), imidazoles ( For example, imidazole, imidazoline, oxyimidazole, etc.), acetoacetate (eg, acetoacetate C _1-4 alkyl ester such as ethyl acetoacetate, etc.) and the like can be mentioned.

These blocking agents can be used alone or in combination of two or more. Of these blocking agents, ketoximes (particularly, C _3-6 dialkyl ketoximes such as methyl ethyl ketoxime) are preferred in view of performing the polyimide formation at a relatively low temperature of 200 ° C. or lower.

  In the reaction between the urethane prepolymer and the blocking agent, the ratio of the blocking agent is used in excess relative to the urethane prepolymer, for example, 2 mol or more with respect to 1 mol of the isocyanate group of the urethane prepolymer. (For example, 2 to 10 mol), preferably 1.5 mol or more (for example, 1.5 to 5 mol), more preferably about 1.05 mol or more (for example, 1.05 to 2 mol). Good. In the reaction between the precursor and the other component, a solvent or a catalyst may be newly added, and the kind and ratio thereof are the same as described above. The reaction conditions are the same as described above.

  After completion of the reaction, the end-capped urethane prepolymer as the product is separated by a conventional separation method, for example, separation means such as concentration, precipitation (or precipitation), extraction, filtration, or a combination of these. It can be purified. Usually, the solvent component may be separated from the product after completion of the reaction using vacuum distillation or the like.

  The weight average molecular weight of the end-capped urethane prepolymer (A) thus obtained can be selected, for example, from the range of about 500 to 30,000, for example, 700 to 20,000, preferably 800 to 10,000. 000, more preferably about 1000 to 5,000 (particularly 1200 to 4000).

(B) Acid anhydride The acid anhydride (B) may have a plurality of acid anhydride groups, and is a tetracarboxylic dianhydride, particularly a conventional acid anhydride used in a polyimide resin. Certain aromatic or alicyclic tetracarboxylic dianhydrides can be utilized. Aromatic or alicyclic tetracarboxylic dianhydrides include monocyclic or fused-ring aromatic tetracarboxylic dianhydrides (for example, pyromellitic dianhydride and naphthalene tetracarboxylic dianhydride), And an aromatic tetracarboxylic dianhydride represented by the following formula (2).

(Wherein, X is a direct bond, -O -, - CO -, - S -, - SO 2 - or ^-O-X 1 -O- in showed binding represented, ^{X 1} is a divalent organic Group).

The organic group represented by X ¹ is usually a group containing a hydrocarbon, and may be an aliphatic or alicyclic hydrocarbon group such as an alkylene group or a cycloalkylene group, but from the viewpoint of heat resistance and the like. A group containing an aromatic ring is preferred.

  Examples of the group containing an aromatic ring include an arylene group (eg, phenylene, tolylene, xylylene, naphthylene, etc.), a biphenylene group (eg, 4,4′-biphenylene group, 3,3′-biphenylene group), and a bisphenol residue. [Dimethyldiphenylmethane-4,4′-diyl group (bisphenol A residue), diphenylmethane-4,4′-diyl group (bisphenol-F residue), diphenylcarbonyl-4,4′-diyl group, diphenylsulfonyl-4 , 4'-diyl group (bisphenol-S residue), diphenylthio-4,4'-diyl group, diphenyloxy-4,4'-diyl group, etc.].

  Aromatic tetracarboxylic dianhydrides can be used alone or in combination of two or more. Among these aromatic tetracarboxylic dianhydrides, monocyclic aromatic tetracarboxylic dianhydrides such as pyromellitic dianhydride are preferable from the viewpoint of mechanical properties and heat resistance.

(Curable resin composition)
The curable resin composition of this invention contains the said urethane prepolymer (A) and an acid anhydride (B), and is used as a precursor of a polyimide resin. The resin composition of the present invention can be prepared as a (semi) solid or liquid material according to the type and molecular weight of the prepolymer (A), and when the urethane prepolymer (A) has a fluorene skeleton, Can be prepared as a solid. Furthermore, since the terminal isocyanate group of the urethane prepolymer (A) is sealed with a blocking agent, the solid mixture (compound) having a fluorene skeleton is excellent in storage stability and handleability. That is, since the resin composition of the present invention is stable, it is excellent in handleability as a molding material and can be used for molding as it is without using a solvent as in the prior art. Furthermore, as will be described later, the resin composition is excellent in moldability and processability, and the resin composition can be easily imidized at a low temperature in a short time.

  The ratio of both components is such that the equivalent ratio of the end-capped isocyanate group of the urethane prepolymer (A) and the acid anhydride group of the acid anhydride (B) is 1 / 0.5 to 1/3. For example, 1 / 0.8 to 1 / 2.0, preferably 1 / 0.9 to 1 / 1.5, more preferably 1/1 to 1 / 1.2 (particularly 1 /1.1) or so. The heat resistance and toughness of the cured product can be improved by blending both components in such a range (particularly, an excess ratio of the acid anhydride).

  The curable resin composition of the present invention further contains conventional additives such as crosslinking or curing agents, antifoaming agents, coating properties improving agents, thickeners, lubricants, stabilizers (antioxidants, ultraviolet absorbers, heat Stabilizers, light-resistant stabilizers, etc.), dyes, pigments, antistatic agents, flame retardants, flame retardant aids, anti-blocking agents, fillers, gelling agents and the like. Moreover, you may mix | blend polycarboxylic acid (Dicarboxylic acid, trimellitic acid, or its anhydride), and may introduce | transduce an amide bond into hardened | cured material. These additives can be used alone or in combination of two or more.

  The curable resin composition of the present invention can be easily prepared by mixing the urethane prepolymer (A) and the acid anhydride (B) by a conventional mixing method. In the present invention, since the curable resin composition does not substantially contain a solvent, it has excellent storage stability, and problems such as decomposition of the prepolymer do not occur.

[Curing method and cured product of curable resin composition]
The curable resin composition of the present invention can be made into a polyimide resin (polyimide molded article) by heating or thermosetting as it is and imidizing without using a solvent. As the molding method, for example, in the case of a liquid resin composition, injection molding, compression molding, transfer molding, cast molding, etc. can be used. In the case of a (semi) solid resin composition, injection molding, compression, etc. Molding (pressure molding) can be used. In particular, in the case of a solid resin composition, a thick molded body can be easily obtained simply by hot pressing (powder pressing) a powdery compound.

  The heating temperature for curing the resin composition is, for example, about 100 to 300 ° C, preferably 150 to 250 ° C, more preferably about 170 to 220 ° C (particularly 180 to 200 ° C). In the present invention, by heating at a temperature in this range, the blocking agent can be rapidly removed and imidized at the same time. The heating time is, for example, about 10 minutes to 2 hours, preferably about 20 minutes to 1.5 hours, and more preferably about 30 minutes to 1.2 hours. In the present invention, it can be cured at a relatively low temperature and in a short time, and it is not necessary to raise the temperature stepwise unlike the curing of polyamic acid, so that it is excellent in productivity.

  When pressure-molding a solid compound, the pressure is, for example, 5 to 50 MPa, preferably 10 to 45 MPa, and more preferably about 20 to 40 MPa.

  The cured product (polyimide resin) obtained by such a method has high heat resistance. For example, in the case of a polyimide having a fluorene skeleton, the glass transition temperature is 250 ° C. or higher (for example, 250 to 400 ° C.). The temperature is preferably about 260 to 350 ° C., more preferably about 280 to 330 ° C., and the 10% weight loss temperature is 250 ° C. or more (for example, 250 to 400 ° C.), preferably 260 to 380 ° C., more preferably 280 to 350 ° C. Denotes about degrees Celsius.

  The cured product of the present invention is not limited to a two-dimensional structure (film shape, sheet shape, plate shape, etc.), and can also form a three-dimensional structure. Furthermore, the thickness of the molded body can also be selected from a wide range of about 0.01 μm to 10.0 mm depending on the application, and unlike conventional polyimide, since no solvent is used, it is possible to form a thick wall, For example, a molded body having a thickness of about 0.1 to 10.0 mm (particularly 2.0 to 5.0 mm) can be formed.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

Example 1
84.22 g of dry N-methyl-2-pyrrolidone (NMP) was added to 10.02 g of 9,9-bis [4- (2-hydroxyethoxy) phenyl] fluorene (BPEF, Osaka Gas Chemical Co., Ltd.) Further, 9.64 g of 1,5-naphthalene diisocyanate (NDI, manufactured by Mitsui Chemicals Polyurethane Co., Ltd.) was added and stirred at room temperature for 15 minutes to completely dissolve the added NDI. To this solution, 1.02 g of NMP solution of di-n-butyltin dilaurate (DTD, manufactured by Nacalai Tesque) diluted to 1% by weight was added, and the mixture was further stirred for 1 hour, and urethane having an isocyanate group at the terminal A prepolymer was obtained. When the isocyanate group content (NCO%) of this prepolymer was measured, it was 7.80%. The presence of isocyanate groups was confirmed by IR analysis of the reaction solution. Subsequently, 3.77 g of 2-butanone oxime was added to the reaction solution and stirred at room temperature for 3 hours to block the terminal isocyanate group. The disappearance of the isocyanate group was confirmed by IR analysis of the reaction solution. The reaction solution was dropped into 500 ml of methanol, and the precipitated white solid was filtered and dried to obtain 11.79 g of BPEF-NDI blocked urethane prepolymer in a yield of 50%.

Example 2
To 11.70 g of diphenylmethane diisocyanate (MDI, manufactured by Nippon Polyurethane Industry Co., Ltd.), 40.01 g of dried dioxane and 1.02 g of a dioxane solution of DTD diluted to 1% by weight were added. BPEF (0.004 g) was dissolved in 49.32 g of dried dioxane, added to the solution containing MDI, and stirred at room temperature for 1.5 hours to obtain a urethane prepolymer having an isocyanate group at the terminal. When the isocyanate group content (NCO%) of this prepolymer was measured, it was 8.00%. The presence of isocyanate groups was confirmed by IR analysis of the reaction solution. Subsequently, 3.80 g of 2-butanone oxime was added to the reaction solution and stirred at room temperature for 2 hours to block the terminal isocyanate group. The disappearance of the isocyanate group was confirmed by IR analysis of the reaction solution. The reaction solution was added dropwise to 500 ml of methanol, and the precipitated white solid was filtered and dried to obtain 14.35 g of a BPEF-MDI blocked urethane polymer in a yield of 57%.

Example 3
0.087 g of pyromellitic dianhydride (PMDA) (0.5 equivalent ratio with respect to the urethane prepolymer), 0.17 g (1 g of the blocked urethane polymer of BPEF-NDI obtained in Example 1) Similarly, a mixture (polyimide resin precursor) blended at a ratio of 1.0) and 0.26 g (also equivalent ratio of 1.5) was prepared. This mixture was pressed with a pressure molding machine heated to 200 ° C. at a pressure of 30 MPa for 1 hour to obtain a polyimide resin (cured product) film having a thickness of 0.3 mm. The glass transition temperature of the film having an equivalent ratio of 1.0 was 309 ° C., and the 10% weight reduction temperature was 288 ° C.

Example 4
0.089 g of pyromellitic dianhydride (PMDA) (0.5 equivalent ratio with respect to the urethane prepolymer), 0.18 g (based on 1 g of the blocked urethane polymer of BPEF-MDI obtained in Example 2) Similarly, a mixture (polyimide resin precursor) blended at a ratio of 1.0) and 0.27 g (also equivalent ratio of 1.5) was prepared. This mixture was pressed with a pressure molding machine heated to 200 ° C. at a pressure of 30 MPa for 1 hour to obtain a polyimide resin (cured product) film having a thickness of 0.3 mm. The glass transition temperature of the film having an equivalent ratio of 1.0 was 323 ° C., and the 10% weight reduction temperature was 318 ° C.

Comparative Example 1
To a three-necked separable flask, 8.71 g of 9,9-bisaniline fluorene (BAF, manufactured by JFE Chemical Co., Ltd.) was added, and further 70.04 g of dried NMP was added. While bubbling this solution with nitrogen and stirring at 0 ° C., 5.74 g of PMDA was added to the solution, stirred with a mechanical stirrer for 2 hours, and then stirred at room temperature for 17 hours. The reaction solution was added dropwise to 1.5 liters of distilled water, and the resulting solid was washed with methanol and dried to obtain 22.22 g of polyamic acid containing NMP. The weight average molecular weight of the polyamic acid was 37900, and the number average molecular weight was 6390.

Comparative Example 2
17.27 g of polyamic acid containing NMP was obtained in the same manner as in Comparative Example 1 except that 4.97 g of 4,4′-methylenedianiline (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of BAF. The weight average molecular weight of the polyamic acid was 44400, and the number average molecular weight was 7890.

Comparative Example 3
A dimethylformamide solution containing 23% by weight of the polyamic acid obtained in Comparative Example 1 was cast on a glass plate, dried and thermally imidized by heating. The heat treatment was performed at 120 ° C. for 30 minutes, and then performed at 150 ° C., 200 ° C., 250 ° C., 300 ° C., and 350 ° C. for 10 minutes each stepwise to obtain a polyimide film. The glass transition temperature of the film was 349 ° C., and the 3% weight loss temperature was 500 ° C.

Comparative Example 4
A dimethylformamide solution containing 23% by weight of the polyamic acid obtained in Comparative Example 2 was cast on a glass plate, dried and thermally imidized by heating. The heat treatment was performed at 120 ° C. for 30 minutes, and then performed at 150 ° C., 200 ° C., 250 ° C., 300 ° C., and 350 ° C. for 10 minutes each stepwise to obtain a polyimide film. The glass transition temperature of the film was not detected, but the 3% weight loss temperature was 500 ° C.

  The polyimide molded body of the present invention not only has high heat resistance and chemical resistance, but also has excellent moldability. Therefore, a film or an adhesive (insulating film, insulating film, insulating tape) that requires heat resistance or chemical resistance is required. Not limited to insulating varnish, etc., molded articles in various fields, such as casings and parts of electrical and electronic equipment (connectors, variable resistors, circuit wiring boards, capacitors, printed circuit boards, membrane switches, heating elements, drives) Part, transformer, generator, etc.), machine / equipment (automobile, passenger car, aircraft, missile, motor, electric motor, computer, etc.) and the like.

Claims (6)

A curable resin composition comprising a urethane prepolymer (A) having a terminal isocyanate group sealed with a blocking agent and an acid anhydride (B) ,
The urethane prepolymer (A) is a prepolymer obtained by end-capping a reaction product of a diol and a diisocyanate represented by the following formula (1) with ketoximes, and the acid anhydride (B) is an aromatic tetracarboxylic acid. A curable resin composition which is an acid dianhydride .

(In the formula, Ar represents an aromatic hydrocarbon ring, R ¹ represents a cyano group, a halogen atom or a hydrocarbon group, R ² represents a hydrocarbon group, an alkoxy group, a cycloalkoxy group, an aryloxy group, an aralkyloxy group. , An alkylthio group, a cycloalkylthio group, an arylthio group, an aralkylthio group, an acyl group, a halogen atom, a nitro group, a cyano group or a substituted amino group, A ¹ represents an alkylene group, k is an integer of 0 to 4, m And n is an integer of 0 or more) The curable resin composition according to claim 1, wherein the diisocyanate is an aromatic diisocyanate. And a terminal blocked isocyanate group of the urethane prepolymer (A), the equivalent ratio of acid anhydride groups of the acid anhydride (B) is the former / the latter = 1 / 0.5 to 1/3 the is claim 1 or 2. The curable resin composition according to 2. The manufacturing method of the polyimide molded body which heats the curable resin composition in any one of Claims 1-3 . The manufacturing method of Claim 4 heated at 180-300 degreeC, without using a solvent. A polyimide molded body obtained by the method according to claim 4 or 5 .