JP2000248178A - Polyimide precursor solution, its preparation, coating obtained from it and preparation of its coating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a solution having a low viscosity despite its high concentration by blending a salt comprising a diamine and a tetracarboxylic acid as its solute. SOLUTION: A salt comprising a diamine of formula I and a tetracarboxylic acid of formula II is blended as a solute. In the formulas, R and R" are each a tetravalent aromatic residue having at least one carbon six member ring; each of the four carbonyl groups bonds directly to a different carbon atom in this residue and each two of the four, as a pair, bond to adjacent carbon atoms in the six-membered ring; R' is a bivalent aliphatic residue; (n) is an integer not less than 1. After the diamine of formula I is obtained by reacting one mol of a diamine of formula III with 0.4-0.8 mol of a tetracarboxylic acid dianhydride in a solvent, a solution is obtained by adding 0.95-1.05 mol of the tetracarboxylic acid of formula II to one mol of the diamine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polyimide precursor solution and a method for producing the same, and more particularly, to a polyimide coating film obtained from the polyimide precursor solution and a method for producing the same.

[0002]

2. Description of the Related Art Polyimides are useful for applications in the electronics field and are used as insulating films and protective coatings on semiconductor devices. In particular, wholly aromatic polyimides have greatly contributed to higher densities, multifunctionality, and the like in flexible circuit boards and integrated circuits because of their excellent heat resistance, mechanical properties, and electrical properties. As described above, a polyimide precursor solution has been used when forming an interlayer insulating film or a protective film of a fine circuit. As this polyimide precursor solution, a polyimide precursor solution containing a polyamic acid represented by the following general formula as a solute is known.

[0003]

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[0004] These polyamic acid solutions are produced by reacting an aromatic diamine and an aromatic tetracarboxylic dianhydride in a solvent.
No. 10999, JP-A-62-275165,
JP-A-64-5057, JP-B-2-38149, JP-B-2-38150, JP-A-1-299
871, JP-A-58-122920, JP-B1-34454, JP-A-58-185624, Journal of Polymer Science, Macromolecular Re.
views Vol.11 P.199 (1976), U.S. Pat.
No. 8, JP-B-3-4588, JP-B7-3
0247, JP-A-7-41556, JP-A-7-62095, JP-A-7-133349, JP-A-7-149896, JP-A-6-207
No. 014, JP-B-7-17870, JP-B-7
-17871, IBM Technical Disclosure Bulle
As disclosed in tinVol.20 No.6 P.2041 (1977) and the like, a solvent using an aprotic polar solvent as a solvent or a solvent as disclosed in JP-A-6-1915. Various polyimide precursor solutions such as those using a mixed solvent selected from a water-soluble ether compound, a water-soluble alcohol compound, a water-soluble ketone compound and water are disclosed.

A polyimide precursor solution in which a polyimide precursor containing an aliphatic compound as a solute as a constituent is dissolved is described in Polymer Vol. 35, p. 4889 (1994).
A polyimide precursor solution in which a polyamic acid (polyamic acid) represented by the following formula and obtained by reacting an aliphatic diamine and an aromatic tetracarboxylic anhydride is disclosed.

[0006]

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[0007] All of these polyimide precursors are solutions of a polymer having a high degree of polymerization. When a polyimide coating is obtained from these polymer solutions, the polymer solution is generally coated on a substrate such as copper or glass. And heated to remove the solvent and imidize to obtain a polyimide coating film.

However, when coating a polymer solution having such a high degree of polymerization, there is a problem that the concentration of the solute must be reduced in order to obtain a viscosity of a coatable solution because of the degree of polymerization. . Also, in order to increase the productivity, increasing the solute concentration increases the viscosity of the solution, which causes a problem that coating cannot be performed, and even if the coating can be performed, it has excellent mechanical and thermal properties. There was a problem that a coating film or a film could not be obtained. Further, the polymer solution is hard to withstand long-term storage, and it has been extremely difficult to store the polymer solution for a long time while maintaining its degree of polymerization.

[0009]

SUMMARY OF THE INVENTION In view of the above situation, an object of the present invention is to provide a polyimide precursor solution having a low viscosity despite its high concentration, a method for producing the same, and a polyimide having good physical properties obtained therefrom. An object of the present invention is to provide a coating film and a method for producing the same.

[0010]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, when a specific monomer is combined, even if it is not a polymer, a solution containing such a monomer has good physical properties. It has been found that a polyimide coating can be obtained. That is, the polyimide precursor solution containing the salt of the monomer composed of the diamine represented by the general formula (1) and the tetracarboxylic acid represented by the general formula (2) has a high concentration of the monomer salt dissolved therein. Nevertheless, it was found that a polyimide film having a low viscosity and a high strength was obtained from this solution, and based on these findings, the present invention has been achieved. Such a finding is a completely surprising finding in view of the fact that only a polyimide precursor having a high degree of polymerization has been known for constituting a polyimide precursor solution.

That is, the gist of the present invention is to provide a diamine represented by the following general formula (1) wherein R is at least 1
Shows a tetravalent aromatic residue containing six carbon six-membered rings, four carbonyl groups being directly linked to different carbon atoms in the residue, two of four being paired, R ′ is a divalent aliphatic residue, and n is an integer of 1 or more, bonded to an adjacent carbon atom in the 6-membered ring. And a tetracarboxylic acid represented by the following general formula (2), wherein R ″ represents a tetravalent aromatic residue containing at least one carbon 6-membered ring,
The four carbonyl groups are directly linked to different carbon atoms in this residue, with two of the four pairs forming a pair and being bonded to adjacent carbon atoms in the six-membered carbon ring. ] As a solute.

[0012]

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Second, in a solvent, a diamine represented by the following general formula (3) [wherein R 'represents a divalent aliphatic residue. ]
0.4 to 0.8 mol of the following general formula (4) per 1 mol
Wherein R is a tetravalent aromatic residue containing at least one carbon 6-membered ring,
The two carbonyl groups are directly linked to different carbon atoms in this residue, with two of the four pairs being linked to adjacent carbon atoms in the six-membered carbon ring. To obtain a diamine represented by the general formula (1), and 1 mol of the diamine represents a compound represented by the general formula (2) wherein R ″ is a tetravalent group containing at least one carbon 6-membered ring. Indicates an aromatic residue,
The four carbonyl groups are directly linked to different carbon atoms in this residue, with two of the four pairs forming a pair and being bonded to adjacent carbon atoms in the six-membered carbon ring. ] In an amount of from 0.95 to 1.05 mol.

[0014]

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Third, there is a polyimide coating film obtained from the polyimide precursor solution. Fourthly, there is provided a method for producing a polyimide coating film, which comprises applying the polyimide precursor solution onto a substrate and heating the solution to imidize the substrate.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. First, terms used in the present invention will be described.

(1) Polyimide An organic polymer in which 80% by mole or more of the repeating unit of the polymer chain has an imide structure. And this organic polymer shows heat resistance.

(2) Polyimide precursor An organic compound which becomes a polyimide by ring closure by heating or chemical action. Here, ring closure means that an imide ring structure is formed.

(3) Polyimide precursor solution The polyimide precursor is dissolved in a solvent. Here, the solvent refers to a compound which is liquid at 25 ° C.

(4) Viscosity The rotational viscosity at 20 ° C. was measured using a DVL-BII digital viscometer (B-type viscometer) manufactured by Tokimec Co., Ltd.

(5) Solute Concentration This is a numerical value in which the weight ratio of the polyimide precursor in the solution is expressed in percentage.

(6) Polyimide coating film A polyimide film formed on a substrate such as copper, aluminum and glass. Among these polyimide coatings, those used in close contact with the substrate are called polyimide coatings, and those used after being peeled off from the substrate are called polyimide films.

Next, the present invention will be described. In the polyimide precursor solution of the present invention, a salt composed of a diamine represented by the general formula (1) and a tetracarboxylic acid represented by the general formula (2) is dissolved in a solvent as a solute. In the diamine represented by the general formula (1), R represents a tetravalent aromatic residue containing at least one carbon 6-membered ring, and four carbonyl groups are directly linked to different carbon atoms in the residue. , Two of the four are paired and are attached to adjacent carbon atoms in the six-membered carbon ring. Specific examples of R include the following.

[0024]

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Particularly, R is preferably the following.

[0026]

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R 'represents a divalent aliphatic residue, and specific examples of R' include the following.

[0028]

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Particularly, R 'is preferably as follows.

[0030]

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In the diamine represented by the general formula (1), n represents an integer of 1 to 20, and n is preferably in the range of 1 to 10 in consideration of the viscosity of the polyimide precursor solution.

In the tetracarboxylic acid represented by the general formula (2), R ″ represents a tetravalent aromatic residue containing at least one carbon 6-membered ring, and four carbonyl groups are different carbon atoms in this residue. It is directly connected to an atom, and two of the four are paired and are attached to adjacent carbon atoms in a six-membered carbon ring. Specific examples of R ″ include those described above as R, and preferred examples thereof include the same. The diamine represented by the general formula (1) and the tetracarboxylic acid represented by the general formula (2) In the salt, the same R and R ″ may be used or different.

In the solution of the present invention, any solvent can be used as a solvent, as long as it can dissolve a salt composed of a diamine represented by the general formula (1) and a tetracarboxylic acid represented by the general formula (2). And aprotic polar solvents, ether compounds and water-soluble alcohol compounds.

Specifically, examples of the aprotic polar solvent include N-methylpyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, hexamethylphosphoramide, N, N'-
Dimethylimidazolidinone and the like, and examples of the ether compound include 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 Chole monomethyl ether, polyethylene glycol, polypropylene glycol, tetrahydrofuran, dioxane, 1,2-dimethoxyethane, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, and the like. Examples of the water-soluble alcohol compound include methanol, ethanol, 1-propanol, and 2- Propanol, tert-
Butyl alcohol, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 2- Butene
Examples include 1,4-diol, 2-methyl-2,4-pentanediol, 1,2,6-hexanetriol, diacetone alcohol, and the like, and the above compounds may be used alone or as a mixture of two or more. Can be.

Of these, particularly preferred examples include N, N-dimethylformamide and N, N-
Examples include dimethylacetamide and N-methylpyrrolidone, and examples of the mixed solvent include combinations of N-methylpyrrolidone and diethylene glycol monomethyl ether, N-methylpyrrolidone and methanol, N-methylpyrrolidone and 2-methoxyethanol, and the like.

In the present invention, the concentration of the polyimide precursor in the polyimide precursor solution is preferably 20% by weight or more.
More preferably, it is 20 to 85% by weight. When the concentration is less than 20% by weight, it may be necessary to repeatedly apply the coating to obtain a predetermined film thickness. On the other hand, when the concentration exceeds 85% by weight, the viscosity may increase, and the coating may be difficult. The viscosity of the polyimide precursor solution depends on the coating method described below, but is preferably 0.1 to 100 poise, and is preferably 0.2 to 100 poise.
85 poise is more preferred. If the viscosity exceeds 100 poise, coating may be difficult, while if it is less than 0.1 poise, the film thickness may be uneven after coating.
The polyimide precursor solution in the present invention has the general formula (1)
Can be produced by adding a tetracarboxylic acid represented by the general formula (2) to a diamine solution represented by the following formula:

Here, as a preferred example, a tetracarboxylic dianhydride represented by the general formula (4) is reacted with a diamine represented by the general formula (3) in a solvent of an aprotic polar compound, whereby A method for producing a polyimide precursor solution by adding a diamine solution represented by the formula (1) and then adding a tetracarboxylic acid represented by the general formula (2) will be described.

First, an aromatic tetracarboxylic dianhydride represented by the general formula (4) and an aliphatic diamine represented by the general formula (3) are reacted in an aprotic polar compound. A solution of the indicated diamine is obtained. Next, an aromatic tetracarboxylic acid represented by the general formula (2) is added to the reaction solution. The reaction of the tetracarboxylic dianhydride represented by the general formula (4) with the dian represented by the general formula (3) to obtain the diamine represented by the general formula (1) is performed by reacting 1 mol of the diamine with the tetracarboxylic dianhydride. It is preferably 0.4 to 0.8 mol, more preferably 0.45 to 0.55 mol of tetracarboxylic dianhydride per 1 mol of diamine. 0.4 to 4 moles of tetracarboxylic dianhydride per mole of diamine
Outside the range of 0.6 mol, it is difficult to obtain the diamine represented by the general formula (1). Furthermore, the addition ratio of the aromatic tetracarboxylic acid represented by the general formula (2) is 0.95 to 1.05 mol, preferably 0.1 to 1 mol of the diamine represented by the general formula (1).
97 to 1.03 mol. If the addition ratio of the aromatic tetracarboxylic acid represented by the general formula (2) is out of the range of 0.95 to 1.05 mol, it becomes difficult to obtain a target salt. The reaction temperature is preferably −30 to 80 ° C., more preferably −20 to 60 ° C., throughout the reaction.

In synthesizing the diamine solution represented by the general formula (1), the order of mixing the monomer and the solvent may be any order. When using a mixed solvent as a solvent, separate monomers are dissolved or suspended in each solvent,
They are mixed and reacted at a predetermined temperature and time under stirring to obtain a diamine solution represented by the general formula (1). In addition, the method of adding the tetracarboxylic acid represented by the general formula (2) is as follows:
Alternatively, it is added as a solution.

Further, the polyimide precursor solution of the present invention may contain, if necessary, fillers such as organosilane, pigment, conductive carbon black and metal particles, abrasives, dielectrics, lubricants and the like. Other known additives can be added as long as the effects of the present invention are not impaired. In addition, other polymers and solvents such as water-insoluble ethers, alcohols, ketones, esters, halogenated hydrocarbons, and hydrocarbons can be added as long as the effects of the present invention are not impaired.

In order to form a polyimide film from the polyimide precursor solution, the polyimide film is extruded from a slit-shaped nozzle or coated on a substrate using a bar coater or the like, dried to remove the solvent, and then imidized. Then, it can be manufactured by peeling off from the substrate. In order to obtain a polyimide coating, a polyimide precursor solution is applied onto a substrate by a conventionally known spin coating method, spray coating method, immersion method, etc., and after drying and removing the solvent,
It is obtained by imidization.

As described above, the polyimide precursor solution of the present invention, the film and the coating obtained therefrom are, for example,
It is used in the production of heat-resistant insulating tapes, heat-resistant adhesive tapes, high-density magnetic recording bases, capacitors, films for FPC, and the like. Further, for example, it is used for manufacturing molding materials and molded products such as sliding members filled with fluororesin or graphite, structural members reinforced with glass fiber or carbon fiber, bobbins of small coils, sleeves, and tubes for terminal insulation. . Also,
It is 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 such as wire and cable insulation coatings, solar cells, low temperature storage tanks, space insulation, integrated circuits, slot liners, and the like. Further, it is used for the production of ultrafiltration membranes, reverse osmosis membranes, and gas separation membranes. Also, a yarn having heat resistance,
It is also used in the production of woven and non-woven fabrics.

[0043]

The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 2.73 g (23.5 mmol) of hexamethylenediamine
1) was dissolved in 24.0 g of dimethylacetamide,
Kept. To this, 3.78 g of 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride (11.75 mm
ol) was gradually added over 30 minutes to obtain a diamine represented by the following formula.

[0045]

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After stirring for 1 hour, 3,3 ', 4,4'-
4.20 g of benzophenonetetracarboxylic acid (11.7
5 mmol), and the mixture was heated to 60 ° C. and further stirred for 1 hour. As a result, a uniform brown transparent solution was obtained (solute concentration: 30% by weight). When the viscosity of this solution was measured, it was 0.44 poise. This solution is added at room temperature
There was no change in viscosity after stirring for 2 hours. Further, using this solution, a film applicator was used to cast a film having a thickness of 50 μm on a glass plate, dried at 80 ° C. for 1 hour in a nitrogen atmosphere, and then imidized by heating at 250 ° C. for 3 hours in a nitrogen atmosphere. When the coating film was peeled off from the glass plate, a polyimide film was obtained. The thickness of this polyimide film was 12.0 μm, and was measured according to JIS K-7.
The tensile strength measured according to 127 is 12.3 kg
/ Mm ² .

Example 2 As in Example 1, 2.78 g of hexamethylenediamine
(24.0 mmol) in dimethylacetamide 23.4
g, and 3.79 g (18.0 mmol) of 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride.
Was added to obtain a diamine represented by the following formula.

[0048]

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After stirring for 1 hour, 3,3 ', 4,4'-
2.11 g of benzophenonetetracarboxylic acid (6.0 m
mol) of 8.9 g (35.0 mmol).
After stirring for 1 hour, a homogeneous brown transparent solution was obtained.
(Solute concentration 30% by weight). Measure the viscosity of this solution
As a result, it was 2.0 poise. This solution is at room temperature
There was no change in viscosity after stirring for 12 hours. More real
A polyimide film was prepared in the same manner as in Example 1.
The thickness of this polyimide film is 12.2 μm.
And the tensile strength is 11.9 kg / mm ^TwoMet.

Example 3 In Example 2, N was used instead of dimethylacetamide.
Except that -methyl-2-pyrrolidone was used, the procedure was the same as in Example 2, to obtain a brown-brown transparent solution. (Solute concentration: 30% by weight) Further, a polyimide film was prepared in the same manner as in Example 1. The thickness of this polyimide film is 11.8
μm, and the tensile strength was 13.1 kg / mm ² .

Example 4 1.40 g (7.0 mmol) of dodecamethylenediamine
Was dissolved in 17.7 g of dimethylformamide and kept at 8 ° C. To this, 1.72 g (5.3 mmol) of 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride was gradually added over 30 minutes to obtain a diamine represented by the following formula.

[0052]

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After stirring for 1 hour, 3,3 ', 4,4'-
0.61 g of benzophenonetetracarboxylic acid (1.7 m
mol), and the mixture was heated to 60 ° C. and further stirred for 1 hour to obtain a uniform yellow transparent solution (solute concentration: 20% by weight). When the viscosity of this solution was measured,
It was 0.21 poise. The viscosity of this solution did not change even after stirring at room temperature for 12 hours. Further, using this solution, a film applicator was used to apply 50 μm on a glass plate.
m, and then dried at 80 ° C. for 1 hour under a nitrogen atmosphere, and then heated and imidized at 250 ° C. for 3 hours under a nitrogen atmosphere, and then the coating film was peeled off from the glass plate. Obtained. The thickness of this polyimide film is 8.1 μm and the tensile strength is 9.3 kg /
mm ² .

[0054]

As described above, in the polyimide precursor solution of the present invention, the solute is not a polymer but a salt of a monomer,
Despite being dissolved at a high concentration, the solution has a low viscosity. And the polyimide coating film obtained from the polyimide precursor solution of the present invention has good physical properties. Therefore, the polyimide precursor solution of the present invention has an excellent effect in a spin coating method used for forming an interlayer insulating film of a large-scale integrated circuit or a protective film.
Further, according to the method for producing a polyimide precursor solution of the present invention, the polyimide precursor solution can be easily produced, and according to the method for producing a polyimide coating film, a polyimide coating film can be easily produced. it can.

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Claims (7)

[Claims] 1. A diamine represented by the following general formula (1): wherein R is a tetravalent aromatic residue containing at least one carbon 6-membered ring, and four carbonyl groups are different R 'is a divalent aliphatic residue, n' is directly linked to a carbon atom, two of four are paired, and are bonded to adjacent carbon atoms in a six-membered carbon ring. Represents an integer of 1 to 20. And a tetracarboxylic acid represented by the following general formula (2) wherein R ″ is at least one carbon atom containing at least one carbon 6-membered ring.
A four-valent aromatic residue, wherein four carbonyl groups are directly linked to different carbon atoms in the residue, and two of the four are paired with adjacent carbons in the six-membered carbon ring. Attached to an atom. ], As a solute. Embedded image 2. The polyimide precursor solution according to claim 1, wherein R ″ in the general formula (2) is as follows. Embedded image 3. The polyimide precursor solution according to claim 1, wherein R ′ in the general formula (1) is as follows. Embedded image 4. The polyimide precursor solution according to claim 1, wherein the solute concentration is 20% by weight or more and the viscosity is 100 poises or less. 5. In a solvent, a diamine represented by the following general formula (3) wherein R ′ represents a divalent aliphatic residue. ] 0.4 to 0.8 mol per mol of tetracarboxylic dianhydride represented by the following general formula (4) wherein R is a tetravalent aromatic residue containing at least one carbon 6-membered ring. And the four carbonyl groups are directly linked to different carbon atoms in the residue, two of the four are paired, and are bonded to adjacent carbon atoms in a six-membered carbon ring. I have. To obtain a diamine represented by the general formula (1), and 1 mol of the diamine represents a compound represented by the general formula (2) wherein R ″ is a tetravalent group containing at least one carbon 6-membered ring. Denotes an aromatic residue, wherein the four carbonyl groups are directly linked to different carbon atoms in the residue, two of the four being paired,
It is attached to an adjacent carbon atom in the member ring. 2. The method for producing a polyimide precursor solution according to claim 1, wherein 0.95 to 1.05 mol of the tetracarboxylic acid is added. Embedded image 6. A polyimide coating film obtained from the polyimide precursor solution according to claim 1. 7. A method for producing a polyimide coating film, comprising applying the polyimide precursor solution according to claim 1 onto a substrate, and heating and imidizing the substrate.