JPH07324134A - Polyamic acid solution and its production - Google Patents

Abstract

PURPOSE:To obtain a polyamic acid solution which can give a polyimide molding or coating film excellent in flexibility and free from any aprotic polar solvent and has a viscosity suitable for being molded CONSTITUTION:This solution is one comprising a polyamic acid and a solvent, wherein the polyamic acid comprises structural units of the formula and has an intrinsic viscosity [eta] of 0.6 dl/g or above, the solvent is a compound having an etheric group and an alcohlic hydroxyl group in the molecule, and the concentration of the polyamic acid is 13wt.% or above.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a polyamic acid solution and a method for producing the same.

[0002]

[Prior Art] Journal of Polymer Scienc
e, Macromolecular Reviews) Vol. 11 (1976) p. 164, Table 2 describes solvents that dissolve polyamic acid. In this table, as specific solvents, N, N
-Dimethylformamide (DMF), N-methyl-2-
Pyrrolidone (NMP), hexamethylphosphoramide (HMPA), N-methylcaprolactam, dimethylsulfoxide (DMSO), N-acetyl-2-pyrrolidone, N, N-dimethylacetamide (DMAc) and the like are listed. These are so-called aprotic polar solvents and have a dipole moment of about 3.0.
It has a greater polarity than Debye, and the DM
The dipole moments of Ac, NMP, DMSO and DMF are 3.7 Debye, 4.1 Debye, 4.3 Debye and 3.
It's 9 Debai. It is also described that these solvents can be used as a polymerization solvent when a polyamic acid is obtained by polymerizing a diamine and a tetracarboxylic dianhydride at the same time as being a solvent for dissolving a polyamic acid.

Further, on pages 199 to 205 of the same document,
It is described that a polyimide coating or a polyimide film can be obtained by coating a substrate with a polyamic acid solution dissolved in these aprotic polar solvents, distilling off the solvent and imidizing. Also, US Pat. No. 42385
No. 28 is polyamic acid, solvent [eg NMP / acetone, NMP / cellosolve, NMP / xylene, NMP
/ Toluene, NMP / toluene and (2-ethoxyethanol) -cellosolve / acetone] and a nonionic fluorocarbon surfactant combination.

Japanese Patent Publication No. 3-4588 discloses an aprotic polar organic solvent (DMAc, NMP, DMSO,
A polyamic acid solution comprising a polyamic acid, selected from DMF), a polyamic acid, a halogenated aliphatic hydrocarbon, a specific organic solvent and an organic silane is disclosed. In addition, IBM Technical Bulletin of November 1977 (IBM Technical
Disclosure Bulletin, Vol. 20, No. 6, p. 2041, discloses a polyamic acid solution formed by mixing DMSO and pyromellitic dianhydride, and NMP and diaminodiphenyl ether.

However, DMAc, NMP, DMSO, which have been used as solvents for these polyamic acids,
Since an aprotic polar solvent such as DMF has a large dipole moment as pointed out in the following documents, it strongly associates with polyamic acid as a solute [Journal of Polymer Science (Journal of Polymer Science).
Science) A-1 Volume 4 2607-2616 (196)
6), Vol. 25, 2005-2010 (196).
6), Vol. 25, 2479-2491 (198).
7), Journal of Industrial Chemistry, Vol. 71, No. 9, 1559-1564.
P. (1968), Proceedings of ANREC '91, pp. 1742-1745], the solvent and solute had a strong solvation, so that there were problems as described below when producing a polyimide film or coating. . Furthermore, as described in Japanese Patent Publication No. 3-4588, these solvents have a problem that they have a large surface tension and a high viscosity due to their large dipole moment.

That is, the DMAc which has been conventionally used,
In a solution of a polyamic acid dissolved in an aprotic polar solvent such as NMP, DMSO, or DMF, the stability of the solution over time is poor, and it is difficult to maintain constant working conditions during molding and coating, and at the same time during molding. It was difficult to remove the solvent during coating. Further, the conventional polyamic acid solution is a so-called low-temperature solution solution in which a diamine such as diaminodiphenyl ether and a tetracarboxylic dianhydride such as pyromellitic dianhydride are polymerized in the aprotic polar solvent as described above. It has been manufactured legally. It has been believed that the polymerization solvent in this case must be a good solvent that dissolves the monomer at a high concentration and does not contain water. That is, when water coexists in the solvent, the hydrolysis reaction of the acid anhydride proceeds, so it is necessary to carry out the reaction in a strict dehydration system, and there is a problem that the reaction apparatus becomes complicated. Further, since the polar solvent is expensive, there is a problem that the manufacturing cost becomes high. Further, when formed into a molded product or a coated product, there is a problem that a large amount of residual solvent causes insufficient electrical properties of the resulting molded product or coated product. There is also a problem that the solvent remaining in the molded body is decomposed at a high temperature during use to generate harmful carbon monoxide.

In order to solve such a problem, the inventors of the present invention have disclosed in JP-A-6-1915 that a mixed solvent selected from a water-soluble ether compound, a water-soluble alcohol compound, a water-soluble ketone compound and water. , Or a polyamic acid solution using a compound having an ether group and an alcoholic hydroxyl group in the same molecule as a solvent, and a method for producing the same. However, with this method, a polyamic acid solution having a sufficient degree of polymerization can be obtained only when the concentration is low, but a polyamic acid solution having a high concentration and a high degree of polymerization could not be obtained. Therefore, JP-A-6-
The high-concentration polyamic acid solution obtained by the method of No. 1915 had a low rotational viscosity and was difficult to handle when producing a film or a coating. In addition, the polyimide film or coating obtained from this high-concentration polyamic acid solution was not sufficiently flexible. Therefore, the concentration is high,
There has been a demand for a polyamic acid solution having a high degree of polymerization, an appropriately high viscosity, and no aprotic polar solvent.

[0008]

In view of the above situation, an object of the present invention is to provide a polyimide molded body or a polyimide coating film which is excellent in flexibility and does not contain an aprotic polar solvent and is suitable for molding. A polyamic acid solution having viscosity and a method for producing the same.

[0009]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that they are compounds having an ether group and an alcoholic hydroxyl group in the same molecule without using an aprotic polar solvent. When a tetracarboxylic dianhydride and a diamine are reacted in a solvent at a temperature not exceeding 20 ° C, a polyamic acid solution having a high concentration and a high degree of polymerization and a viscosity suitable for molding is obtained. It was found that the polyimide molded product and the polyimide coating obtained from the polyamic acid solution have excellent flexibility, and thus reached the present invention.

That is, the gist of the present invention consists of a polyamic acid and a solvent, and the polyamic acid has the formula (1)

[0011]

[Chemical 2]

The polyamic acid has a constitutional unit represented by and the intrinsic viscosity [η] of the polyamic acid is 0.6 dl / g or more,
The solvent is a compound having an ether group and an alcoholic hydroxyl group in the same molecule, and the polyamic acid concentration is 13% by weight.
A polyamic acid solution characterized in that the above,
This polyamic acid solution contains an aromatic diamine containing 4,4′-diaminodiphenyl ether (DADE) and pyromellitic dianhydride (PMDE) in a compound having an ether group and an alcoholic hydroxyl group in the same molecule. Aromatic tetracarboxylic acid dianhydride and polyamic acid forming to be mixed so that the concentration is 13% by weight or more, 20
It can be produced by reacting at a temperature of not higher than ° C.

The present invention will be described in detail below. The polyamic acid solution of the present invention comprises a polyamic acid and a solvent, wherein the polyamic acid has a structural unit represented by the formula (1), and is an organic polymer which is closed by heating or a chemical action to form a polyimide. Anything will do. The most preferable polyamic acid having a structural unit represented by the formula (1) is a polyamic acid derived from DADE and PMDA, and a polyamic acid having 100% of the structural unit represented by the formula (1) is particularly preferable. preferable.

A preferred polyamic acid constituting the polyamic acid other than the above is an aromatic polyamic acid, and in particular, a homopolymer or copolymer of a polyamic acid having a repeating unit represented by the formula (2), or a partial imide. Homogenized polyamic acid homopolymers or copolymers are preferred.

[0015]

[Chemical 3]

R in the formula (2) represents a tetravalent aromatic residue containing at least one carbon 6-membered ring, and each of the 4 valences forms a pair and is adjacent to each other in the carbon 6-membered ring. Characterized by being bonded to a carbon atom. Specific examples of R include the following.

[0017]

[Chemical 4]

Particularly, R is preferably the following.

[0019]

[Chemical 5]

R'represents a divalent aromatic residue having 1 to 4 carbon 6-membered rings. Specific examples of R'include the following.

[0021]

[Chemical 6]

[0022]

[Chemical 7]

Further, as R ′, the following are particularly preferable.

[0024]

[Chemical 8]

Further, the polyamic acid in the present invention has an intrinsic viscosity [η] of 0.6 dl / g or more. [Η] is 0.
If it is less than 6 dl / g, it is difficult to obtain the desired flexible polyimide molded article and coating. [Η] is a value directly related to the molecular weight of the polymer, and the concentration of the polyamic acid in the N, N-dimethylacetamide solvent is 0.5.
Weight% and by measuring the time for the polymer solution to flow through a constant volume capillary of a standard viscometer at 30 ° C. and for the solvent only to flow, it can be calculated using the following equation: C is the concentration of polyamic acid in the solution,
Expressed in grams of polyamic acid per dl of solution.

[0026]

[Equation 1]

In the present invention, when the polyamic acid is partially imidized, the imidization ratio is preferably 35 mol% or less. Polyamic acid imidized in excess of 35 mol% tends to have reduced solubility. The partial imidization ratio is 604 cm ⁻¹ and 882 cm in the infrared absorption spectrum.
It can be determined by measuring the absorption based on ⁻¹ , and the partial imidization ratio can be calculated using the following formula. However, a and a ′ are represented by the following equations, a is the absorbance ratio of the subject, and a ′ is the ring closure rate of 10
It is the absorbance ratio of 0%.

[0028]

[Equation 2]

[0029]

[Equation 3]

As a method of ring-closing, a conventionally known method such as a method by heating or a method using a ring-closing agent such as acetic anhydride or pyridine can be applied.

In the present invention, as the solvent, a compound having an ether group and an alcoholic hydroxyl group in the same molecule is used. In such a solvent, the dipole moment is 3.
A solvent of 0 Debye or less is preferably used.

As the solvent having an ether group and an alcoholic hydroxyl group in the same molecule, for example, 2-methoxyethanol, 2-ethoxyethanol, 2- (methoxymethoxy) ethoxyethanol, 2-isopropoxyethanol, 2-butoxyethanol. , Tetrahydrofurfuryl alcohol, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol, triethylene glycol monoethyl ether, tetraethylene glycol, 1
-Methoxy-2-propanol, 1-ethoxy-2-propanol, dipropylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monomethyl ether, polyethylene glycol, polypropylene glycol and the like. Among them, 2-methoxyethanol and diethylene glycol monomethyl ether are particularly preferable. The dipole moments of 2-methoxyethanol and diethylene glycol monomethyl ether are 2.04 and 2.75.

The concentration of the polyamic acid in the polyamic acid solution in the present invention is 13% by weight or more, and 15
-40% by weight is more preferable. When the concentration is less than 13% by weight, the viscosity is low, and when applied on a substrate, handling is difficult, such as dripping of the coating film, and it is difficult to obtain a good coating film or film. If it exceeds 40% by weight, the viscosity becomes too high, which may cause problems in use.

Further, the solution of the polyamic acid of the present invention may contain, for example, a filler such as an organic silane, a pigment, conductive carbon black and metal particles, an abrasive, a dielectric, a lubricant, etc., if necessary. Other known additives can be added within a range that does not impair the effects of the present invention. In addition, other polymers such as water-insoluble ethers, alcohols,
Solvents such as ketones, esters, halogenated hydrocarbons and hydrocarbons can be added within the range not impairing the present invention. Further, a solvent such as a water-soluble ether compound, a water-soluble alcohol compound, a water-soluble ketone compound and water can be added to the polyamic acid solution of the present invention within a range not impairing the present invention.

Next, a method for producing an aromatic polyamic acid solution will be described as a preferred example of the present invention. D
An aromatic diamine containing ADE and an aromatic tetracarboxylic dianhydride containing PMDA are combined with an ether group and an alcoholic hydroxyl group in the same molecule so that the concentration of polyamic acid produced is 13% by weight or more. React in the compounds that have. At this time, the reaction temperature must be 20 ° C. or lower. When the polymerization is carried out at a temperature higher than 20 ° C., the degree of polymerization does not increase, and a polyamic acid having [η] of 0.6 dl / g or more cannot be obtained. There is no problem if the lower limit of the temperature is higher than the freezing point of the solvent. The time required for the reaction is the time until the inside of the reaction system becomes a uniform transparent solution.
2 hours or more is preferable, and 24 hours or more is more preferable.
The reaction ratio between the aromatic tetracarboxylic dianhydride and the aromatic diamine is preferably equimolar, but it is possible to arbitrarily adjust the degree of polymerization of the polyamic acid by slightly changing the ratio of these monomers. it can.

The order of mixing the monomers and the solvent in carrying out the polymerization may be any order, but the aromatic tetracarboxylic dianhydride component is kept as a solid in the solution or suspension of the aromatic diamine component. From the viewpoint of workability, it is preferable to add gradually. In this way, the polyamic acid is composed of the polyamic acid and the solvent, the polyamic acid has the structural unit represented by the formula (1), the concentration is 13% by weight or more, and the intrinsic viscosity [η] of the polyamic acid is 0. It is possible to obtain a polyamic acid solution having a content of 0.6 dl / g or more and a solvent having a compound having an ether group and an alcoholic hydroxyl group in the same molecule.

The viscosity of the polyamic acid solution obtained by such a method is preferably 30 poise or more when measured at 20 ° C. with a rotary viscometer. A polyamic acid solution having a poise of less than 30 poise may be difficult to handle due to dripping when coating a base material to form a coating. The viscosity of the polyamic acid solution has no particular upper limit,
If the viscosity is too high, it may be difficult to handle depending on the case. Further, in order to convert the polyamic acid solution into a partially imidized polyamic acid solution, the polyamic acid solution is heated at 60 to 100 ° C. for 1 to 200 minutes without distilling the solvent, or pyridine and acetic anhydride are used. , A known imidization catalyst such as picoline and acetic anhydride, 2,6-lutidine and acetic anhydride is added,
The reaction may be performed at 1 ° C. for 1 to 100 hours with stirring. The addition amount of the imidization catalyst is preferably about 0.01 to 0.35 mol of acetic anhydride and about 0.01 to 3.5 mol of a base such as pyridine, 2,6-lutidine or triethylamine, relative to 1 mol of the monomer. .

The solution of the polyamic acid of the present invention, the moldings and the coatings obtained therefrom are, for example, heat-resistant insulating tapes,
It is used for manufacturing heat-resistant adhesive tapes, high-density magnetic recording bases, capacitors, films for flexible wiring boards (FPC), and the like. Further, for example, sliding members filled with fluororesin or graphite, structural members reinforced with glass fibers or carbon fibers, small coil bobbins, sleeves,
It is used to manufacture molding materials and molded products such as tubes for terminal insulation. It is also used for manufacturing laminated materials such as insulating spacers for power transistors, magnetic head spacers, spacers for power relays, and spacers for transformers. It is also used for the production of enamel coating materials for wire / cable insulation coatings, solar cells, low temperature storage tanks, space insulation materials, integrated circuits, slot liners, etc. Also, an ultrafiltration membrane,
Used for manufacturing reverse osmosis membranes and gas separation membranes. Further, it is also used for manufacturing heat resistant yarn, woven fabric, non-woven fabric and the like.

[0039]

EXAMPLES The present invention will now be described in detail with reference to examples, but the present invention is not limited thereto. Example 1 9.57 g of DADE and 113 g of diethylene glycol monomethyl ether were poured into a three-necked flask and sufficiently stirred to disperse DADE. The temperature of this slurry is 1
Maintaining at 5 ° C., 10.43 g of PMDA was added as powder, and after 24 hours, a transparent solution of polyamic acid was obtained. At this time, the polyamic acid concentration was 15.0% by weight,
[Η] was 0.7 dl / g, and the rotational viscosity of this solution was 116.2 poise.

This solution was applied onto a copper foil (thickness: 35 μm, rolled copper foil) so that the thickness would be 100 μm, but no dripping occurred from the coating film and the handling was good. This polyamic acid-coated copper foil is dried in a hot air dryer at 60 ° C. for 3 hours, then fixed with a metal frame, and at 80 ° C. for 1 hour.
Heat treatment was performed at 200 ° C. for 10 hours to imidize the polyamic acid. The polyimide coating thus obtained is excellent in flexibility, and even when the polyimide coating is bent so that the copper foil surfaces are brought into contact with each other, the coating may be cracked or peeled from the copper foil which is the base material. There wasn't.

Example 2 9.57 g DADE and 2-methoxyethanol 113
g was poured into a three-necked flask and sufficiently stirred to disperse DADE. Keep the temperature of this slurry at 15 ° C.
10.43 g of MDA was added as powder, and after 12 hours, a transparent solution of polyamic acid was obtained. At this time, the polyamic acid concentration was 15.0% by weight, and [η] was 1.0 dl.
/ G and the rotational viscosity of this solution was 98.5 poise. This solution was applied onto a copper foil (thickness: 35 μm, rolled copper foil) so as to have a thickness of 200 μm, but no dripping occurred from the coating film, and the handling was good. This copper foil was dried in a hot air drier at 60 ° C. for 3 hours, then fixed with a metal frame and heat-treated at 80 ° C. for 1 hour and 200 ° C. for 10 hours to complete imidization of the coating film. The polyimide coating thus obtained is excellent in flexibility, and even when the polyimide coating is bent so that the copper foil surfaces are brought into contact with each other, the coating may be cracked or peeled from the copper foil which is the base material. There wasn't.

Example 3 9.57 g of DADE, 2-methoxyethanol 100
g, 11 g of THF and 3 g of methanol were poured into a three-necked flask and sufficiently stirred to disperse DADE. Keeping the temperature of this slurry at 15 ° C., 10.43 g of PMD
A was added as powder, and after 12 hours, a transparent solution of polyamic acid was obtained. At this time, the polyamic acid concentration was 15.
0% by weight, [η] was 1.0 dl / g, and the rotational viscosity of this solution was 95.6 poise. This solution was applied onto a glass plate so as to have a thickness of 200 μm, but no dripping occurred from the coating film and the handling was good. After this glass plate was dried in a hot air dryer at 60 ° C. for 1 hour, the coating film was peeled off from the glass plate and fixed in a metal frame in a loosened state in consideration of the amount of contraction accompanying imidization. Imidization was performed by performing heat treatment at 200C for 1 hour at 200C for 10 hours. The polyimide film thus obtained had a thickness of 16 μm, was excellent in flexibility, and did not break even when bent.

Comparative Example 1 9.57 g of DADE and 113 g of diethylene glycol monomethyl ether were poured into a three-necked flask and sufficiently stirred to disperse DADE. Set the temperature of this slurry to 3
Keeping at 0 ° C. or higher, 10.43 g of PMDA was added as powder, and after 24 hours, a transparent solution of polyamic acid was obtained. At this time, the concentration of polyamic acid was 15.0% by weight, [η] was 0.5 dl / g, and the rotational viscosity of this solution was 20.8 poise. 100 μm of this solution
Was applied to a copper foil (thickness: 35 μm, rolled copper foil) so as to have a thickness of. This copper foil is dried in a hot air drier at 60 ° C for 3 hours, then fixed with a metal frame, and at 80 ° C for 1 hour, 20
Heat treatment was performed at 0 ° C. for 10 hours to complete imidization of the coating film. The polyimide coating thus obtained had poor flexibility, and when the polyimide coating was turned upside down and bent so that the copper foil surfaces were aligned with each other, the coating cracked and there was a portion peeled off from the copper foil as the base material.

Comparative Example 2 9.57 g of DADE and 113 g of 2-methoxyethanol
Was poured into a three-necked flask and sufficiently stirred to disperse DADE. Maintaining the temperature of this slurry solution at 40 ° C. or higher, 10.43 g of PMDA was added as powder, and after 24 hours, a transparent solution of polyamic acid was obtained. At this time, the concentration of polyamic acid was 15.0% by weight, and [η] was 0.
It was 5 dl / g and the rotational viscosity of this solution was 7.6 poise. This solution was applied onto a copper foil (thickness: 35 μm, rolled copper foil) so as to have a thickness of 200 μm, but dripping occurred from the coating film and it was difficult to handle. This copper foil was dried in a hot air drier at 60 ° C. for 3 hours, then fixed with a metal frame and heat-treated at 80 ° C. for 1 hour and 200 ° C. for 10 hours to complete imidization of the coating film. The polyimide coating thus obtained had poor flexibility, and when the polyimide coating was turned upside down and bent so that the copper foil surfaces were aligned with each other, the coating cracked and there was a portion peeled off from the copper foil as the base material.

Comparative Example 3 9.57 g of DADE, 2-methoxyethanol 100
g, 11 g of THF and 3 g of methanol were poured into a three-necked flask and sufficiently stirred to disperse DADE. Keep the temperature of this slurry solution at 40 ° C. or higher to prevent PMDA1
0.43 g was added as powder, and after 12 hours, a transparent solution of polyamic acid was obtained. At this time, the concentration of polyamic acid was 15.0% by weight, [η] was 0.5 dl / g, and the rotational viscosity of this solution was 7.2 poise. This solution was coated on a glass plate to a thickness of 200 μm and dried in a hot air drier at 60 ° C. for 1 hour, and then the coating film was tried to be peeled from the glass plate, but it did not become a film, It just shattered and could not be removed.

Comparative Example 4 4.785 g of DADE, 90 g of 2-methoxyethanol
Was poured into a three-necked flask and sufficiently stirred to disperse DADE. Keep the temperature of this solution below 20 ° C
DA5.22g was added as a powder, and a transparent solution of polyamic acid was obtained after 12 hours. At this time, the polyamic acid concentration was 10.0% by weight, and [η] was 1.1 dl / g.
And the rotational viscosity of this solution was 3.5 poise.
This solution was applied on a rolled copper foil (thickness: 35 μm) so as to have a thickness of 200 μm, but dripping occurred from the coating film, and handling was difficult.

[0047]

As described above, the polyamic acid solution of the present invention has a high concentration and a high degree of polymerization, and a viscosity suitable for molding. Therefore, when obtaining a polyimide molded body or a polyimide coating, it is very easy to handle, and the obtained polyimide molded body or polyimide coating is excellent in flexibility. Further, since the aprotic polar solvent is not used, it goes without saying that the polyimide molded body and the polyimide coating do not contain the aprotic polar solvent, and the solvent used also has a low solvation with the polyamic acid and thus remains. Not enough solvent. Further, such a polyamic acid solution can be easily manufactured by the manufacturing method of the present invention.

Claims (2)

[Claims] 1. A polyamic acid and a solvent, wherein the polyamic acid has the formula (1): The polyamic acid has an intrinsic viscosity [η] of 0.6 dl / g or more, the solvent is a compound having an ether group and an alcoholic hydroxyl group in the same molecule, and the polyamic acid concentration is Is 13% by weight or more, and a polyamic acid solution. 2. An aromatic diamine containing diaminodiphenyl ether and an aromatic tetracarboxylic dianhydride containing pyromellitic dianhydride are produced in a compound having an ether group and an alcoholic hydroxyl group in the same molecule. 2. The polyamic acid is added so that the concentration thereof is 13% by weight or more, and the reaction is carried out at 20 ° C. or lower.
A method for producing the polyamic acid solution described.