JPH0881555A - Polyimide copolymer and its production - Google Patents

Abstract

PURPOSE: To obtain a polyimide copolymer having high strengths and a low coefficient of thermal expansion and used for a flexible printed wiring board by cyclizing a polyamic acid prepared by polymerizing a specified aromatic diamine with a tetracarboxylic dianhydride through dehydration. CONSTITUTION: An aromatic diamine component based on 1,4-bis (4- aminobenzoyloxy)benzene and 4,4'-diaminodiphenyl ether is polymerized with a tetracarboxylic dianhydride to obtain a polyamic acid, apd this acid is cyclized through thermal or chemical dehydration to make a polyimide polymer mainly consisting of repeating units of formulas I and II (wherein R is an aromatic group). The molar ratio I/II of the copolymer is 5/95 to 90/10 desirably 20/80 to 70/30. A solution of the polyamic acid in a polar organic solvent is cast on a belt to form a film, and this film is heated and imidated to obtain a polyimide film. This film has high strengths and a low coefficient of thermal expansion and a low water absorption and is suited for a fine-pattern flexible printed wiring board.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention provides a polyimide having excellent heat resistance, high mechanical strength, low coefficient of thermal expansion and low water absorption, which is suitable as a base material for fine patterned flexible printed wiring boards and the like. The present invention relates to a copolymer and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, polyimide resins have been extremely superior in heat resistance and chemical resistance.
It is known to have excellent electrical and mechanical properties and other properties. For example, Japanese Patent Publication No. 36-1099.
Well-known is a wholly aromatic polyimide having a high flexibility obtained from 4,4′-diaminodiphenyl ether and pyromellitic dianhydride as disclosed in JP-A No.

Since this polyimide resin contains a highly flexible ether bond in its main chain, it is a fully aromatic polyimide but is highly flexible, but on the other hand, it has a low elastic modulus and poor thermal dimensional stability. there were. Particularly, the polyimide resin which has been widely used in the past has a linear expansion coefficient of about 3 × 10 ⁻⁵ /
It was as large as ℃, the thermal dimensional stability was poor, and when it was laminated with a metal or the like, it was likely to warp or curl.

On the other hand, in recent years, there has been an increasing demand for a polyimide resin having more excellent thermal dimensional stability and excellent mechanical strength, and various studies have been conducted. Among such attempts, there are many attempts to improve mechanical properties, thermal dimensional stability, etc. by using two or more kinds of aromatic diamines. However, in any of these approaches, the thermal dimensional stability and mechanical properties of the polyimide resin could not be satisfied at the same time.

Further, the polyimide resin has a significantly higher water absorption rate than other plastics. Therefore, it has a drawback that dimensional stability and insulation are deteriorated. In recent years, there is an increasing demand for polyimide resins having excellent low hygroscopicity and excellent mechanical strength, and various studies have been conducted. Among such attempts, many attempts are made to improve low hygroscopicity by using an aromatic diamine or an aromatic dianhydride containing a hydrophobic group. However, in each of these approaches, low hygroscopicity improvement is obtained, but mechanical properties, especially elastic modulus and tensile strength, tend to decrease, satisfying both low hygroscopicity and mechanical properties. It wasn't something.

The present invention has been made in view of the above circumstances.
To provide a polyimide copolymer having excellent heat resistance and high mechanical strength, a low coefficient of thermal expansion and a low water absorption rate, which is suitable as a base material for a fine patterned flexible printed wiring board and the like, and a method for producing the same. With the goal.

[0007]

Means and Actions for Solving the Problems As a result of intensive studies made by the present inventors to achieve the above object, 1,4-
Bis (4-aminobenzoyloxy) benzene, 4,
An aromatic diamine containing 4'-diaminodiphenyl ether as a main component and an aromatic tetracarboxylic acid dianhydride are polymerized to obtain a polyamic acid, which is thermally or chemically dehydrated and cyclized to give the following general compounds. A polyimide copolymer containing a repeating unit represented by the formula (1) and a repeating unit represented by the following general formula (2) as main constitutional units, and preferably a repeating unit represented by the following general formula (1) and the following general formula: The repeating unit represented by the formula (2) has a molar ratio of (1) / (2)
A polyimide copolymer containing repeating units of 5/95 to 90/10 is obtained, the polyimide copolymer has excellent mechanical strength, and has a low coefficient of linear expansion and a low water absorption coefficient. Moreover, they have found that they have a high elastic modulus and flexibility, and have completed the present invention.

[0008]

Embedded image (However, in the formula, R represents a tetravalent aromatic group.)

Therefore, the present invention is a polyimide copolymer, preferably containing a repeating unit represented by the above general formula (1) and a repeating unit represented by the above general formula (2) as main constitutional units. The repeating unit (1) and the repeating unit (2) have a molar ratio of (1) / (2) = 15/95 to 90.
/ 10 polyimide copolymer, and 1,4-bis (4-aminobenzoyloxy) benzene and 4,4'-
An aromatic diamine containing diaminodiphenyl ether as a main component and tetracarboxylic acid dianhydride are polymerized to obtain a polyamic acid, and the polyamic acid is then thermally or chemically dehydrated and ring-closed. Provided is a method for producing a polyimide copolymer containing a repeating unit represented by (1) and a repeating unit represented by the general formula (2) as main constituent units.

The present invention will be described in more detail below.

The polyimide copolymer of the present invention contains a repeating unit represented by the following general formula (1) and a repeating unit represented by the following general formula (2) as main constituent units.

[0012]

[Chemical 3]

In the above formula, R is a tetravalent aromatic group, which is derived from the main skeleton of the tetracarboxylic dianhydride described later.

Here, the repeating unit (1) and the repeating unit (2) are present in the polyimide copolymer in a molar ratio of (1) /
(2) = 5/95 to 90/10, especially 20/80 to 70
It is desirable to exist in a ratio of / 30. If the molar ratio of the repeating unit (1) exceeds 90%, the flexibility of the polyimide copolymer will be extremely lowered and the water absorption will be high. When the molar ratio of the repeating unit (2) exceeds 95%,
In some cases, the water absorption of the polyimide copolymer becomes high, and the effects of improving the linear expansion coefficient and elastic modulus cannot be sufficiently obtained.

The above-mentioned polyimide copolymer is a high molecular weight polymer, and the viscosity as a polyamic acid has a logarithmic viscosity of 0.5-0.5 at a measurement temperature of 30 ° C. when measured in 0.5 g / 100 ml DMF. It is preferably 5 dl / g.

The polyimide copolymer of the present invention comprises 1,4-
Bis (4-aminobenzoyloxy) benzene and 4,4
It can be produced by polymerizing an aromatic diamine containing'-diaminodiphenyl ether as a main component and tetracarboxylic dianhydride to obtain a polyamic acid, and then dehydrating and ring-closing the polyamic acid.

Here, as the aromatic diamine, 1,4
It is most preferable to use only -bis (4-aminobenzoyloxy) benzene and 4,4'-diaminodiphenyl ether, but it is possible to use other aromatic diamine compounds together with these aromatic diamines. Aromatic diamines that can be used in combination include 4,4′-
Bis (4-aminophenoxy) biphenyl, 4,4'-
Diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, bis {4- (4-aminophenoxy) phenyl} sulfone, bis {4- (3-aminophenoxy) phenyl} sulfone, bis {4- (2-aminophenoxy) ) Phenyl} sulfone, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (4
-Aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 1,4-bis (4-aminophenyl) benzene, bis {4- (4-aminophenoxy) phenyl} ether, 4,4 ' -Diaminodiphenylmethane, bis (3-methyl-4-aminophenyl) methane, bis (3-chloro-4-aminophenyl) methane, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 3,3'- Dimethyl-4,4'-diaminobiphenyl, 3,3'-dichloro-4,4'-diaminobiphenyl, 2,2 ', 5,5'-tetrachloro-4,4'-
Diaminobiphenyl, 3,3'-dicarboxy-4,4
′ -Diaminobiphenyl, 3,3′-dihydroxy-
4,4'-diaminobiphenyl, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,
4'-diaminodiphenylmethane, 4,4'-diaminobiphenyl, 4,4'-diaminooctafluorobiphenyl, 2,4'-diaminotoluene, paraphenylenediamine, metaphenylenediamine, 4,4'-diaminobenzanilide, 3 , 4'-diaminobenzanilide,
4,3'-diaminobenzanilide, 2,2-bis {4
-(4-aminophenoxy) phenyl} propane, 2,
2-bis {4- (4-aminophenoxy) phenyl} hexafluoropropane, 2,2-bis (3-hydroxy-4-aminophenyl) propane, 2,2-bis (3-
Examples thereof include hydroxy-4-aminophenyl) hexafluoropropane, 9,9-bis (4-aminophenyl) -10-hydro-anthracene and orthotolidine sulfone. Further, it is possible to use a part of tetraamines such as 3,3 ′, 4,4′-tetraaminodiphenyl ether. Of these aromatic diamines,
Aromatic diamines other than 1,4-bis (4-aminobenzoyloxy) benzene can be used within a range in which the objects and effects of the present invention are achieved, but the amount of these other aromatic diamine compounds used is the total. It is preferably used in an amount of 10 mol% or less, particularly 5 mol% or less, based on the aromatic diamine compound.

Specific examples of the tetracarboxylic dianhydride include pyromellitic dianhydride, 3,3 ', 4.
4'-biphenyltetracarboxylic dianhydride, 2,3
3'4'-biphenyltetracarboxylic dianhydride, 3,
3 ', 4,4'-benzophenone tetracarboxylic dianhydride, 2,3,6,7-naphthalene tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic dianhydride, 2, 2-bis (3,4-dicarboxyphenyl) propane dianhydride, bis (3,4-dicarboxyphenyl) ethane dianhydride, bis (3,4-dicarboxyphenyl) etheric acid dianhydride, 1, 1-bis (3,4
-Carboxyphenyl) ethanoic acid dianhydride, 3,4
9,10-Perylene tetracarboxylic dianhydride, benzene-1,2,3,4-tetracarboxylic dianhydride, 2,
3,6,7-anthracene tetracarboxylic dianhydride,
Examples thereof include 1,2,7,8-phenylenetetracarboxylic dianhydride, and these can be used alone or in combination of two or more.

When the above-mentioned aromatic diamine is reacted with the aromatic tetracarboxylic dianhydride, the aromatic tetracarboxylic dianhydride is mixed in a ratio of 96 to 105 mol with respect to 100 mol of the aromatic diamine mixture. Desirably, if it is out of this range, the degree of polymerization of the produced polyimide copolymer may not be increased and sufficient mechanical strength may not be maintained.

The reaction between the aromatic diamine and the aromatic tetracarboxylic dianhydride can be carried out in an organic polar solvent. In this case, examples of the organic polar solvent used include sulfoxide-based solvents such as dimethyl sulfoxide, formamide-based solvents such as N, N-dimethylformamide, N, N-diethylformamide, N, N-dimethylacetamide, N. , Acetamide-based solvents such as N-diethylacetamide, pyrrolidone-based solvents such as N-methyl-2-pyrrolidone, phenol, o-, m-, or p-
Examples thereof include phenol-based solvents such as cresol, xylenol, halogenated phenol and catechol, and hexamethylphosphoramide, γ-butyrolactone and the like. These organic polar solvents may be used singly or as a mixture of two or more, and xylene, an aromatic hydrocarbon-based organic non-polar solvent such as toluene may be used in combination with the organic polar solvent. Is also possible. The amount of the organic polar solvent used is not particularly limited, but the aromatic diamine and the aromatic diamine such that the polyamic acid obtained by the polymerization reaction is dissolved in the organic polar solvent in an amount of 5 to 30% by weight, particularly 10 to 20% by weight. It is preferable to determine the amounts of tetracarboxylic dianhydride and organic polar solvent used.

The above-mentioned polymerization reaction is carried out at 0 to 70 ° C. for 1 hour.
The polyamic acid can be obtained more effectively by conducting the treatment at -50 hours, particularly at 0-30 ° C for 2-24 hours.

The viscosity of the polyamic acid obtained above is not particularly limited, but as described above, 0.5 g / 100 mlD
The logarithmic viscosity when measured in MF at a measurement temperature of 30 ° C. is preferably 0.5 to 5 dl / g, and this is an index of the molecular weight of the polyimide copolymer.

The polyamic acid synthesized as described above can then be dehydrated and ring-closed to produce a polyimide copolymer. As the dehydration ring closure method, for example, a method such as thermal or chemical dehydration ring closure can be adopted.

In the case of thermally dehydrating and ring-closing the polyamic acid, a method of heating at 200 to 500 ° C. for 5 to 120 minutes is preferable.

Further, a method using a dehydrating agent and a catalyst is suitable for the chemical dehydration ring closure. In this case, as the dehydrating agent, aliphatic acid anhydride, aromatic acid anhydride, N, N'-
Dialkyl carbonimide, lower fatty acid halide,
Examples thereof include halogenated lower fatty acid halides, halogenated lower fatty acid anhydrides, allylphosphonic acid dihalides, thionyl halides, etc. These can be used alone or in combination of two or more. The amount of the dehydrating agent used is preferably about 0.1 to 10 mols, and particularly preferably 0.5 to 4 mols, per repeating unit of polyamic acid.

When a catalyst is used, for example, aliphatic tertiary amines such as triethylamine, aromatic tertiary amines such as dimethylaniline, heterocyclic tertiary amines such as pyridine, β-picoline, isoquinoline, etc. These may be used alone or in combination of two or more. The amount of the above-mentioned catalyst used is preferably about 0.01 to 4 mols, and particularly preferably 0.1 to 2 mols per repeating unit of polyamic acid.

To carry out the above chemical dehydration ring closure reaction, 2
0.2 to 20 hours at 0 to 400 ° C, especially 50 to 350 ° C
Therefore, 0.5 to 5 hours is preferable.

In order to obtain a polyimide copolymer in the form of a film, the organic polar solvent of the polyamic acid is cast or coated on a support such as an endless belt to form a film, and the film is formed at 100 to 150 ° C. Dry and add 10-solvent
A polyamic acid self-supporting membrane containing 30% is obtained.
Then, after peeling off this film from the support and fixing the ends, it is heated to about 150 ° C to 250 ° C to remove the solvent, and further dehydrated and imidized at 250 to 500 ° C.
A polyimide film having a thickness of about 10 to 150 μm can be obtained.

The polyimide copolymer thus obtained has excellent heat resistance, high mechanical strength, a low coefficient of thermal expansion and a low water absorption rate, and is a base material for fine-patterned flexible printed wiring boards and the like. Is preferably used as.

[0030]

EXAMPLES The present invention will be specifically described below by showing Examples and Comparative Examples, but the present invention is not limited to the following Examples.

Reference Example First, 1,4-bis (4-aminobenzoyloxy) benzene was synthesized as follows.

1,4-into 500 ml of tetrahydrofuran
Dihydroxybenzene 33.0g (0.300mol)
And 66.8 g (0.660 mol) of triethylamine were dissolved and cooled to 0 ° C., and tetrahydrofuran 1 was added to the solution.
50 ml and p-nitrobenzoyl chloride 116.9 g
A solution in which (0.630 mol) was dissolved was added dropwise so that the temperature of the reaction liquid was 10 ° C or lower. Then, it returned to room temperature and continued stirring for 2 hours.

Next, the precipitate was filtered, washed with tetrahydrofuran, further washed with water and methanol, and dried to obtain white crystals of 1,4-bis (4-nitrobenzoyloxy) benzene. It was The yield was 121.0 g (yield 98.8%). The crude crystal was recrystallized with N, N-dimethylformamide to obtain a pure product.

102.1 g (0.250 mol) of 1,4-bis (4-nitrobenzoyloxy) benzene obtained above was added to 5% Pd / C in 1000 ml of autoclave.
Charged with 3 g and 700 ml of dimethylformamide. Hydrogen was introduced with vigorous stirring at 60 ° C., and stirring was continued until hydrogen absorption was no longer observed.

After cooling, the catalyst was removed by filtration, concentrated under reduced pressure and poured into 1000 ml of water. The precipitate was filtered, washed with water and dried under reduced pressure to give 1,4-bis (4-aminobenzoyl). A light brown white solid of (oxy) benzene was obtained. Yield 83.
It was 6 g (yield 96.0%). The crude crystal was recrystallized with a mixed solvent of dimethylformamide / methanol to obtain a pure product.

[Example 1] 403.2 g of N, N-dimethylformamide was placed in a 1000 ml flask, and 6.967 g (0.020mo) of 1,4-bis (4-aminobenzoyloxy) benzene was added while flowing nitrogen gas.
1) and 4,4'-diaminodiphenyl ether 16.
019 g (0.080 mol) was dissolved in N, N-dimethylformamide. Next, pyromellitic dianhydride 2
Add 1.812 g (0.100 mol) and add 3 at 25 ° C.
Allowed to react for hours.

Next, these amic acid solutions were thinly spread on a glass plate with an applicator and heated in an oven at 110 ° C.
After drying for 60 minutes, peel it off, fix it to the iron frame, and
Desolvation and imidization were conducted at 60 ° C. for 60 minutes and then at 300 ° C. for 60 minutes to obtain a polyimide film having a thickness of about 25 μm. The properties of this polyimide film are shown in Table 1.

[Example 2] 429.8 g of N, N-dimethylformamide was placed in a 1000 ml flask, and 13.934 g (0.040mo) of 1,4-bis (4-aminobenzoyloxy) benzene was introduced while flowing nitrogen gas.
1) and 4,4'-diaminodiphenyl ether 12.
014 g (0.060 mol) was dissolved in N, N-dimethylformamide. Next, pyromellitic dianhydride 2
Add 1.812 g (0.100 mol) and add 3 at 25 ° C.
After reacting for a time, a polyimide film was obtained by the same method as in Example 1. The properties of this polyimide film are shown in Table 1.

[Example 3] 456.5 g of N, N-dimethylformamide was placed in a 1000 ml flask, and 20.902 g (0.060mo) of 1,4-bis (4-aminobenzoyloxy) benzene was added while flowing nitrogen gas.
1) and 4,4'-diaminodiphenyl ether 8.0
10 g (0.040 mol) was dissolved in N, N-dimethylformamide. Next, pyromellitic dianhydride 2
Add 1.812 g (0.100 mol) and add 3 at 25 ° C.
After reacting for a time, a polyimide film was obtained by the same method as in Example 1. The properties of this polyimide film are shown in Table 1.

Example 4 483.2 g of N, N-dimethylformamide was placed in a 1000 ml flask and 27.869 g (0.080 mo) of 1,4-bis (4-aminobenzoyloxy) benzene was added while flowing nitrogen gas.
1) and 4,4'-diaminodiphenyl ether 4.0
05 g (0.020 mol) was dissolved in N, N-dimethylformamide. Next, pyromellitic dianhydride 2
Add 1.812 g (0.100 mol) and add 3 at 25 ° C.
After reacting for a time, a polyimide film was obtained by the same method as in Example 1. The properties of this polyimide film are shown in Table 1.

[Comparative Example 1] 509.8 g of N, N-dimethylformamide was placed in a 1000 ml flask and 34.836 g (0.100 mo) of 1,4-bis (4-aminobenzoyloxy) benzene was added while flowing nitrogen gas.
1) was added and dissolved in N, N-dimethylformamide. Next, 21.812 g of pyromellitic dianhydride (0.
(100 mol) and reacted at 25 ° C. for 3 hours,
A polyimide film was obtained by the same method as in Example 1. The properties of this polyimide film are shown in Table 1.

[Comparative Example 2] 376.5 g of N, N-dimethylformamide was placed in a 1000 ml flask, and 20.024 g (0.100 mol) of 4,4'-diaminodiphenyl ether was added while flowing nitrogen gas. It was dissolved in N-dimethylformamide. Next, 21.812 g of pyromellitic dianhydride (0.100 mo
l) was added and reacted at 25 ° C. for 3 hours, and then a polyimide film was obtained by the same method as in Example 1. The properties of this polyimide film are shown in Table 1.

The methods for measuring the mechanical properties, linear expansion coefficient, water absorption and logarithmic viscosity of the obtained polyimide film are shown below.

Mechanical Properties (Tensile Strength, Elastic Modulus, Elongation ) Measured according to ASTM D882-88.

Linear expansion coefficient Using a thermal analyzer TMA-7000 manufactured by Vacuum Riko Co., Ltd., an average value of linear expansion coefficients at 150 to 200 ° C. was obtained at a temperature rising rate of 5 ° C./min.

Water absorption rate The polyimide film was left at 90% RH for 24 hours, and the weight before and after that was measured to determine the water absorption rate.

The logarithmic viscosity polyamic acid concentration was 0.5 g / 100 ml DMF, and the measurement temperature was 30 ° C.
It was calculated by the following formula.

[0048]

[Equation 1]

Table 1 shows the results of these measurements.

[0050]

[Table 1]

[0051]

INDUSTRIAL APPLICABILITY The polyimide copolymer of the present invention has excellent heat resistance, high mechanical strength, a low coefficient of thermal expansion and a low water absorption, and is used as a base material for a fine patterned flexible printed wiring board or the like. It can be used preferably. Further, according to the production method of the present invention, the excellent polyimide copolymer described above can be easily and surely obtained.

Claims (3)

[Claims] 1. A polyimide copolymer comprising a repeating unit represented by the following general formula (1) and a repeating unit represented by the following general formula (2) as main constituent units. Embedded image (However, in the formula, R represents a tetravalent aromatic group.) 2. The polyimide copolymer according to claim 1, wherein the repeating unit (1) and the repeating unit (2) have a molar ratio of (1) / (2) = 5/95 to 90/10. 3. A polyamic acid is obtained by polymerizing an aromatic diamine containing 1,4-bis (4-aminobenzoyloxy) benzene and 4,4′-diaminodiphenyl ether as main components and tetracarboxylic dianhydride. The method for producing a polyimide copolymer according to claim 1, wherein the polyamic acid is subjected to dehydration ring closure thermally or chemically.