TWI642695B - Polyimide precursor solution - Google Patents

Abstract

An object of the present invention is to provide a polyimide polyimide precursor which is excellent in environmental suitability and excellent in storage stability and leveling property, and which is capable of producing a polyimide body having excellent mechanical strength. The polyamidene precursor solution provided by the present invention is a salt of a polyaminic acid and a weakly basic compound having an acid dissociation constant (pKa) of 8.5 or less and 4.5 or more, and is dissolved in a solvent containing a polyol. to make.

Description

Polyimine precursor solution

This invention relates to polythenimine precursor solutions. The polyimine imide molding system obtained from the polyimine precursor solution has excellent mechanical strength and high heat resistance.

A molded article composed of an aromatic polyimine obtained from an aromatic tetracarboxylic dianhydride and an aromatic diamine is widely used in the electronics industry because of its excellent properties such as heat resistance, mechanical strength, electrical properties, and solvent resistance. Fields, photocopiers, aircraft, etc. The aromatic polyimine is usually dissolved in NMP (N-methyl-2-pyrrolidone) and DMF (N, N-di) because of the lack of solubility. A solution of a guanamine solvent such as methylformamide or DMAC (N,N-dimethylacetamide) is applied to the surface of the substrate, followed by hardening at a high temperature (醯imination). A polyimine molded body such as a film or a belt is obtained. When the solvent in the polyaminic acid solution is the above-described guanamine-based solvent, since the guanamine-based solvent is released into the atmosphere during the formation of the polyimide, it is from the viewpoint of environmental suitability. There is still room for improvement.

A polyiminoimide precursor solution in which the above amide-based solvent is not used is proposed herein.

For example, Patent Documents 1 to 6 propose a polyilylimide precursor solution obtained by dissolving a salt of a polyamic acid and a basic compound in water which is substantially free of an organic solvent.

However, as disclosed in Patent Documents 1 to 6, the polyimine precursor solution containing a high concentration of water has insufficient coating properties when coated on the surface of the substrate because of the high surface tension peculiar to water. The phenomenon of film bounce, or the problem of uneven thickness. Also, there are problems with preservation stability.

Further, Patent Documents 7 and 8 propose that a solvent containing a specific alcohol is used as a reaction solvent, and a tetracarboxylic acid component and a diamine component are reacted in the presence of a strong basic compound such as triethylamine or triethylenediamine. And the obtained polyamidiene precursor solution. However, if an alcohol having a strong basic compound such as triethylamine or triethylenediamine is used as a polymerization solvent, it is difficult to obtain a polyadenimine precursor having a high degree of polymerization, and storage stability is also problematic. .

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. Hei 8-59832

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2002-226582

[Patent Document 3] International Publication No. 2012/8543

[Patent Document 4] International Publication No. 2013/35806

[Patent Document 5] International Publication No. 2013/105610

[Patent Document 6] Japanese Patent Laid-Open Publication No. 2013-144750

[Patent Document 7] Japanese Patent Laid-Open Publication No. 2013-144751

[Patent Document 8] Japanese Patent Laid-Open Publication No. 2014-31445

In order to solve the above problems, an object of the present invention is to provide a polyimide polyimide precursor which is excellent in environmental suitability, good in storage stability and uniform coating property, and which is capable of producing a polyimide-imid molded article having excellent mechanical strength. .

The inventors of the present invention have intensively studied in order to solve the above problems, and as a result, have found that a polyglycine and a salt of a specific basic compound are dissolved in a specific solvent to obtain a uniform polyimine precursor solution from which a machine can be produced. The present invention has been completed by a polyimine molded article having excellent strength.

That is, the gist of the present invention is as follows.

1) A polyimine precursor solution obtained by dissolving a salt of a polyaminic acid, a weakly basic compound having an acid dissociation constant (pKa) of 8.5 or less and 4.5 or more, in a solvent containing a polyol.

2) A polyimine precursor solution as described above, wherein the polyol-containing solvent is a mixed solvent of a polyol and water.

3) The polyimine precursor solution according to the above, wherein the mixed solvent is a water content of less than 70% by mass.

4) A polyimine precursor solution as described above, wherein the polyamic acid is an isolated solid polyamine.

Since the polyimine precursor solution of the present invention does not use a guanamine-based solvent, it has excellent environmental suitability, good storage stability, and uniform coating property, and since a higher boiling solvent such as a polyol is used, Therefore, the process control at the time of molding is easy, and a coating film having a uniform thickness can be obtained. Therefore, the polyimine precursor solution of the present invention is quite suitable as a polyimide precursor solution from which a polyimide composition having excellent properties can be obtained.

The polyfluorene imine precursor aromatic polyimine precursor of the present invention has a homopolymer or copolymer of polyamic acid having a structural unit represented by the general formula (1). The polyimine obtained from the polyimine precursor is preferably a non-thermoplastic polyimide, and the glass transition temperature is preferably at least 250 °C.

Wherein R is a tetravalent aromatic residue containing at least one carbon six-membered ring, and each of the four valences forms a pair, and the two-valent pair of each pair is a carbon atom adjacent to each other in the carbon six-membered ring. provide.

Further, R' represents a divalent aromatic residue having 1 to 4 carbon six-membered rings.

The polyamic acid is obtained by reacting a tetracarboxylic acid component with a diamine component.

The tetracarboxylic acid component is a tetracarboxylic acid (tetracarboxylic acid, dianhydride or esterified product thereof) having an aromatic ring, and specific examples thereof include pyromellitic acid and 3,3',4,4'-linked. Phenyltetracarboxylic acid, 2,3,3',4'-biphenyltetracarboxylic acid, 2,2',3,3'-biphenyltetracarboxylic acid, 4,4'-oxydicarboxylic acid, 3,3',4,4'-tetracarboxylic acid diphenyl ketone, 3,3',4,4'-tetracarboxylic acid diphenyl hydrazine, conjugated triphenyltetracarboxylic acid, cross-linked triphenyltetracarboxylic acid Acids, etc., and mixtures of these.

Among these, pyromellitic acid, 3,3', 4,4'-biphenyltetracarboxylic acid, 3,3',4,4'-tetracarboxylic acid diphenyl ketone are preferred. 4,4'-oxydicarboxylic acid, and mixtures thereof.

Specific examples of the diamine component-based aromatic diamine include p-phenylenediamine, m-phenylenediamine, and 4,4'-diaminodiphenyl ether (4,4'-oxydiphenylamine). 3,4'-oxydiphenylamine, 4,4'-diaminodiphenylmethane, 2,4-toluenediamine, 2,2-bis[4-(4-aminophenoxy)phenyl] Propane, 1,3-bis(4-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene, 3,3'-dihydroxy-4,4'-diamine Biphenyl, bis(4-amino-3-carboxyphenyl)methane, 2,4-diaminotoluene, and the like.

Among these, phenylenediamine, meta-phenylenediamine, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, and mixtures thereof are preferred.

The above polyamic acid is preferably an isolated solid polyamic acid. So-called The use of the isolated solid polyamic acid refers to the use of a solid polyamine which is previously polymerized by another system in the production of the polyimine precursor solution of the present invention. As the solid polyamic acid, for example, a polyamic acid powder obtained by suspension polymerization of a tetracarboxylic acid component and a diamine component can be used. The polyamic acid produced by the suspension polymerization method can be obtained, for example, according to the method described in Japanese Patent No. 2951484, No. 3386856, and the like. That is, it is obtained by reacting the above-mentioned tetracarboxylic acid component and the diamine component in a slight molar amount in a poor solvent which does not dissolve the polyamic acid. The reaction temperature is -20 to 60 ° C, particularly preferably 0 to 30 ° C. According to this, when the reaction is carried out in a poor solvent, since the polyamic acid belonging to the reaction product is not dissolved in the poor solvent and is suspended in the solvent, the solvent can be removed by an ordinary method such as filtration, drying or the like. A powdery polyamine is obtained. Here, the "poor solvent" means a solvent having a solubility of 25 ° C polyglycine of less than 1 g with respect to 100 g of the solvent, and specifically, a solvent such as an ether or a ketone can be used. Among these, THF (tetrahydrofuran), acetone, and the like are preferably used. By such a suspension polymerization method, a solid poly-proline acid having a high degree of polymerization can be obtained, and a polyadenimine precursor solution having a high degree of polymerization can be obtained by using it. The content of the poor solvent in the obtained powdery poly-proline is preferably less than 1% by mass based on the total mass of the powder.

The polyimine precursor solution of the present invention is a weak base having a poly-proline acid having a dissociation constant (pKa) of 8.5 or less and 4.5 or more, preferably 8.5 or less and 5.5 or more, more preferably 8.5 or less and 7.0 or more. The salt composed of the compound is used as a polyimide precursor. Here, the "pKa of a basic compound" means one of the indexes indicating the alkali strength in a quantitative formula, and the acid dissociation constant value of the conjugate acid of the base. That is, the negative logarithm of the equilibrium constant (Ka) of the dissociation reaction in which the proton is released from the acid is expressed by the acid-base titration at a measurement temperature of 25 °C. The greater the pKa value, the stronger the base. The pKa is 8.5 or less and 4.5 Representative examples of the above weakly basic compound include, for example, a nitrogen-containing heterocyclic compound. Specific examples thereof include a pyridine derivative such as pyridine, 2-methylpyridine, 3-methylpyridine or 4-methylpyridine; 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, and 4 An imidazole derivative such as ethyl-2-methylimidazole or 1-methyl-4-ethylimidazole; a quinoline derivative such as quinoline or isoquinoline or the like. Among these, 1,2-dimethylimidazole and 2-ethyl-4-methylimidazole are preferably used. Further, the basic compound having a complex pKa value is defined as the pKa value of the basic compound.

The blending amount of the weakly basic compound with respect to the above polyamic acid is preferably 1 to 4 moles, more preferably 1.5 to 3 moles, per mole of the constituent unit of the polyglycolic acid. The weakly basic compound may be blended in combination of two or more kinds, and in this case, the total blending amount of the above may be within the above range.

The polyimine precursor solution of the present invention can be obtained by adding a solvent containing a weakly basic compound and a polyhydric alcohol to the above polyamic acid and dissolving it to form a solution. Here, the "polyol" means an organic compound having two or more alcoholic hydroxyl groups in one molecule. Specific examples of the polyhydric alcohol include ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, and 1 , 5-pentanediol, 2-butene-1,4-diol, 2-methyl-2,4-pentanediol, glycerin, 2-ethyl-2-hydroxymethyl-1,3-propanediol 1,2,6-hexanetriol, diethylene glycol, dipropylene glycol, triethylene glycol, tetraethylene glycol, and the like. Among these, ethylene glycol and diethylene glycol are preferably used.

As the solvent containing the above polyol, a solvent composed only of a polyhydric alcohol or a mixed solvent of a polyhydric alcohol and water can be used. Any solvent is a polyol that can be used alone One type or a combination of one type or more may be used. From the viewpoint of lowering the raw material cost, a mixed solvent of a polyol and water is preferably used. In the mixed solvent of a polyol and water, from the viewpoints of storage stability, coating uniformity, and film strength, the water content is preferably less than 70% by mass, more preferably less than 60% by mass based on the total mass of the solvent. quality%.

The solvent containing the above-mentioned polyol preferably does not contain a solvent other than the polyol and water, and particularly preferably, the content of the guanamine-based solvent is less than 2% by mass based on the total mass of the solvent, from the viewpoint of environmental suitability. More preferably, the system is less than 1% by mass. The "melamine-based solvent" is an organic solvent having a hydrogen atom or a hydrazine-substituted amide, and may be, for example, N-methyl-2-pyrrolidone or N,N-dimethylformamide. , N, N-dimethylacetamide, and the like.

When the solution is formed, the concentration of the polyimine precursor is preferably from 0.1 to 60% by mass, more preferably from 1 to 40% by mass, and particularly preferably from 10 to 30% by mass. The concentration of the polyimine precursor is calculated as the ratio of the total mass of the polyaminic acid to the weakly basic compound relative to the total mass of the polyimide intermediate solution.

Further, the specific viscosity [η] of the polyimine precursor is preferably 0.7 or more, more preferably 1.0 or more, and particularly preferably 1.2 or more. The larger the value of [η], the more easily the properties such as the strength and the elastic modulus are obtained when the polyimide is formed into a closed loop. Further, [η] is directly related to the molecular weight of the polymer, and is measured in a N,N-dimethylacetamide solvent at a concentration of 0.5% by mass and 25° C. based on the concentration of the polyimide precursor.

The polyamidiamine precursor solution of the present invention can be obtained by directly reacting a tetracarboxylic acid component and a diamine component in a polyol solvent containing a weakly basic compound. Got it. but. According to this, since the decomposition reaction of the above-mentioned tetracarboxylic acid component belonging to the monomer proceeds in the polymerization reaction, it is difficult to obtain a polyamic acid having a high degree of polymerization, and thus, as described above, it is preferred to pass the isolated solid. The polylysine is obtained by dissolving a weakly basic compound in a solvent containing a polyol. When the polyimine precursor solution contains a polyol or water, the molecular weight of the polylysine decreases due to storage for a long period of time. Therefore, it is preferred to form the powdered polyamine into a solution just before the formation of the polyimine. Further, the storage temperature of the obtained polyaminic acid solution is preferably set to 10 ° C or lower, more preferably 0 ° C or lower.

The polyimine precursor solution of the present invention can be processed into a film or a belt by a usual method, or a film can be formed. When processing into a film, if a solution of the polyimide precursor is cast on a substrate such as a glass plate by a coating film trickle to a desired thickness, the solvent is removed, followed by heating to carry out hydrazine imidization. Polyimine film. Similarly, if the solution is applied to a target substrate, dried and heated, the substrate can be coated with polyimide.

Furthermore, the polyamidene precursor solution of the present invention may be blended with, for example, a filler such as a pigment, conductive carbon black, and metal particles, or a lithium secondary battery active material, an abrasive, a dielectric, or a lubricant. A known filler such as a agent. Further, other polymers or solvents such as ethers, monovalent alcohols, ketones, esters, halogenated hydrocarbons, and hydrocarbons may be added to the extent that the effects of the present invention are not impaired.

The film and the film produced by the polyimine precursor solution of the present invention are suitable for, for example, various electrical insulating films (heat-resistant insulating tape, heat-resistant adhesive tape, high-density magnetic film). Recording seat, capacitor, FPC, etc.), intermediate transfer belt for photocopiers, fixing belt for photocopiers, electrodes for lithium secondary batteries, sliding members filled with fluororesin, graphite, etc. Reinforced structural members such as fibers and carbon fibers, various spacers (insulation spacers for power transistors, spacer spacers, spacers for power relays, spacers for transformers, etc.), wires, insulation coatings, and coating materials (Solar cells, low temperature storage tanks, space insulation materials, integrated circuits, tank linings, etc.), ultrafiltration membranes, gas separation membranes, etc.

[Examples]

Hereinafter, the present invention will be more specifically described based on the examples, but the present invention is not limited to the embodiments.

<Modulation of poly-proline powder>

The polyamic acid powder system used in the examples and comparative examples was prepared as follows.

<Polyuric acid powder A>

A poly-proline powder was obtained from pyromellitic dianhydride (PMDA) and 4,4'-oxydiphenylamine (ODA) according to the method described in Example 1 of Japanese Patent No. 2951484. That is, PMDA (21.9 g) was dissolved in THF (500 ml) and kept at 0 °C. 500 ml of a THF solution in which ODA (20.0 g) was slowly added thereto was reacted at 0 ° C for 2 hours to obtain a suspension containing poly-proline. When the poly-proline is isolated from the suspension, a powder of poly-proline is obtained. The [η] of the polyaminic acid at this time was 1.50. This was set to polyamic acid powder A.

<Polyuric acid powder B>

According to the method described in Example 3 of Japanese Patent No. 2951484, polycondensation is obtained from 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) and 4,4'-oxydiphenylamine (ODA). Proline powder. Namely, BPDA (2.96 g) was suspended in THF (50 ml) and kept at 0 °C. 50 ml of a THF solution in which ODA (2.00 g) was slowly added thereto was reacted at 0 ° C for 2 hours to obtain a suspension containing poly-proline. When the poly-proline is isolated from the suspension, a powder of poly-proline is obtained. The [η] of the polyaminic acid at this time was 2.19. This was set to polyamic acid powder B.

<Polyuric acid powder C>

Polylysine powder was obtained from 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) and p-phenylenediamine (PDA). Namely, BPDA (8.06 g) was suspended in 60 ml of acetone and kept at room temperature (20 ° C). A solution in which PDA (2.91 g) was dissolved in 129 ml of acetone was slowly added thereto, and the reaction was carried out for 1 hour at room temperature to obtain a suspension of poly-proline. When the poly-proline is isolated from the suspension, a powder of poly-proline is obtained. The [η] of the polyaminic acid at this time was 1.85. This was set to polyamic acid powder C.

The properties and the like of the polyimine precursor solution obtained in the following examples and comparative examples were evaluated in accordance with the following methods.

<Save stability>

After the polybendimimine precursor solution was allowed to stand at 25 ° C for 100 hours, the specific viscosity of the poly-proline was determined. When the rate of change was less than 10%, the storage stability was rated as "good", and the rate of change was 10 When it is more than %, the preservation stability is rated as "bad".

<Coating property>

The polyimine precursor solution was applied to a glass plate belonging to the substrate using a coating film trickle, and the coating film was applied at 50 ° C for 10 minutes, at 80 ° C for 30 minutes, according to a nitrogen atmosphere. The film was applied at ° C for 30 minutes, at 200 ° C for 20 minutes, at 300 ° C for 20 minutes, and subjected to heat treatment at 350 ° C for 10 minutes to form a polyimide film coating film having a thickness of about 20 μm. Then, the polyimide film was peeled off from the glass plate, and after cutting 10 square centimeters square, the thickness of any 9 places was measured. When the thickness variation range is less than ±10% with respect to the average value, the leveling property is rated as "good", and when the variation is ±10% or more, the leveling property is rated as "bad".

<Film strength characteristics>

The tensile strength of the above polyimine film was measured according to ASTM D882. When the tensile strength of the polyimide film was 12 kg/mm ² or more, the mechanical strength was rated as "good" when the polyimide film was used. When the tensile strength was less than 12 kg/mm ² , the mechanical strength was rated as "poor".

[Example 1]

a mixture of polyamic acid powder A and 1,2-dimethylimidazole (pKa 7.7) (1,2-dimethylimidazole relative to the constituent unit of polyglycolic acid 1 molar used 2.5 mol) It was dissolved in ethylene glycol at 25 ° C to obtain a polyamidene precursor solution A-1 having a concentration of 15% by mass as a polyimide precursor. The property evaluation results of the precursor solution are shown in Table 1.

[Embodiment 2]

a mixture of poly-proline powder B and 1,2-dimethylimidazole (pKa 7.7) (1,2-dimethylimidazole is used in relation to the constituent unit of polyglycolic acid 1 molar 2.5 mol) It was dissolved in ethylene glycol at 25 ° C to obtain a polybendimimine precursor solution B-1 having a concentration of 15% by mass as a polyimide precursor. The property evaluation results of the precursor solution are shown in Table 1.

[Example 3]

The polyimine precursor solution B-2 was obtained in the same manner as in Example 2 except that 2-ethyl-4-methylimidazole (pKa 8.3) was used as the basic compound. The property evaluation results of the precursor solution are shown in Table 1.

[Example 4]

The polyimine precursor solution A-2 was obtained in the same manner as in Example 1 except that diethylene glycol was used as the solvent. The property evaluation results of the precursor solution are shown in Table 1.

[Example 5]

The polyimine precursor solution B-3 was obtained in the same manner as in Example 2 except that diethylene glycol was used as the solvent. The property evaluation results of the precursor solution are shown in Table 1.

[Embodiment 6]

In addition to the solvent, a mixed solvent of ethylene glycol and water is used (the mass ratio of the mixture is ethylene glycol: The polyimine precursor solution A-3 was obtained in the same manner as in Example 1 except that water = 80:20. The property evaluation results of the precursor solution are shown in Table 1.

[Embodiment 7]

A polyimine precursor solution B-4 was obtained in the same manner as in Example 2 except that a solvent (mixing mass ratio of diol: water = 80:20) was used as the solvent. The property evaluation results of the precursor solution are shown in Table 1.

[Embodiment 8]

a mixture of poly-proline powder C and 1,2-dimethylimidazole (pKa 7.7) (1,2-dimethylimidazole relative to the constituent unit of polyglycolic acid 1 molar 2.5 mol) It is dissolved in a mixed solvent of ethylene glycol and water at 25 ° C (mixing mass ratio: diol: water = 80:20) to obtain a polyfluorene having a concentration of 15% by mass as a precursor of polyimine. Imine precursor solution C-1. The property evaluation results of the precursor solution are shown in Table 1.

[Embodiment 9]

A polyimine precursor solution B-5 was obtained in the same manner as in Example 2 except that a solvent mixture of ethylene glycol and water (mixing mass ratio: diol: water = 50:50) was used. The property evaluation results of the precursor solution are shown in Table 1.

[Embodiment 10]

The polyimine precursor solution C- was obtained in the same manner as in Example 8 except that the solvent was a mixed solvent of diethylene glycol and water (mixing mass ratio of diethylene glycol: water = 60:40). 2. The property evaluation results of the precursor solution are shown in Table 1.

[Comparative Example 1]

The polyimine precursor solution A-4 was obtained in the same manner as in Example 1 except that methanol was used as the solvent. However, the polyamic acid powder A was not completely dissolved, and a homogeneous solution could not be obtained.

[Comparative Example 2]

The polyimine precursor solution B-6 was obtained in the same manner as in Example 2 except that the solvent was ethanol. However, the polyamic acid powder B was not completely dissolved, and a homogeneous solution could not be obtained.

[Comparative Example 3]

The polyimine precursor solution B-7 was obtained in the same manner as in Example 2 except that n-butanol was used as the solvent, but the poly-proline powder B was not completely dissolved, and a uniform solution could not be obtained.

[Comparative Example 4]

The polyimine precursor solution A-5 was obtained in the same manner as in Example 1 except that the basic compound was triethylamine (pKa 11.8) which was a strongly basic compound. The results of the evaluation of the properties of the precursor solutions are shown in Table 1.

[Comparative Example 5]

The polyimine precursor solution A-6 was obtained in the same manner as in Example 1 except that the basic compound was a triethylenediamine (pKa 8.8) which is a strongly basic compound. The The results of the evaluation of the characteristics of the precursor solution are shown in Table 1.

[Comparative Example 6]

The polyimine precursor solution B-8 was obtained in the same manner as in Example 2 except that the solvent was changed to water. The results of the evaluation of the properties of the precursor solutions are shown in Table 1.

[Comparative Example 7]

Polyimine precursor solution B-9 was obtained in the same manner as in Example 2 except that water was used as the solvent and the basic compound was triethylamine (pKa 11.8) which was a strongly basic compound. The results of the evaluation of the properties of the precursor solutions are shown in Table 1.

From the above results, it was found that the polyethylenimine precursor solution of the present invention is excellent in both storage stability and leveling property. Moreover, the polyazide obtained from the solution of the polyimide precursor solution is known. The amine film has excellent mechanical strength. Moreover, since the amide-based solvent is not used, it is excellent in environmental suitability.

(industrial availability)

The polyimine precursor solution of the present invention is suitably used for, for example, an electric insulating film such as FPC, a belt for a photocopier, an electrode for a lithium secondary battery, an electric wire, a wire insulation coating, a separation film, and the like.

Claims (2)

A polyamidene precursor solution obtained by dissolving a salt of a weakly basic compound having a polyaminic acid and an acid dissociation constant (pKa) of 8.5 or less and 4.5 or more, dissolved in a solvent, characterized in that it is a polyfluorene. The tetracarboxylic acid component of the amine acid is selected from the group consisting of pyromellitic acid, 3,3', 4,4'-biphenyltetracarboxylic acid, 3,3',4,4'-tetracarboxylic acid diphenyl ketone. One or two or more kinds of 4,4'-oxydicarboxylic acid; the solvent contains ethylene glycol, and the water content ratio is less than 70% by mass. The polyimine precursor solution according to claim 1, wherein the weakly basic compound is 1,2-dimethylimidazole and/or 2-ethyl-4-methylimidazole.