JPH0912883A - Polyamic acid composition - Google Patents

Abstract

PURPOSE: To prepare a compsn. which can be imidated at a low temp. to form a protective film on an electronic component by adding a small amt. of lactam to an org. polar solvent soln. of a polyamic acid comprising particular two amic acid units. CONSTITUTION: An org. polar solvent soln. of a polyamic acid comprising amic acid units represented by formulae I and II [R represents a 4-12 C straight chain aliph. (oxa)hydrocarbon] (I:II unit molar ratio = (97:3) to (70:3) is prepd., and a lactam is added in an amt. of 0.005 to 10wt.% based on the polyamic acid. Pref., biphenyltetracarboxylic acid dihydride is reacted with bis(aminophenoxyphenyl)sulfone and a diamine of a 4-12 C linear (oxa)hydrocarbon in an org. polar solvent to prepare a polyamic acid, and a lactam is added thereto. The org. polar solvent is pref. N,N-dimethylacetamide or N-methyl-2- pyrrolidone. The lactam added is particularly pref. ε-caprolactam. The compsn. is imidated at 220 deg.C or below to form a strong film.

Description

Detailed Description of the Invention

The present invention provides a so-called low-temperature curable polyamic acid composition capable of forming a polyimide film excellent in transparency and non-coloring property and capable of dehydration ring-closure imidization even by heat treatment at a relatively low temperature of 220 ° C. or lower. It is about.

[0002]

2. Description of the Related Art Polyimide has excellent electrical and mechanical properties and heat resistance, and is used in various applications as an electrical and electronic material. However, in general, polyimide is colored yellow, brown, and reddish brown, and its light transmittance is not sufficient, and it is used as a material for image formation, or when it is used as a protective film for optical sensors, solar cells, etc. Was inappropriate. In general, polyimide is used to form a coating film using a solution of its precursor (also referred to as polyamic acid or polyamic acid), and then the coating film is dried at a considerably high temperature for imidization. It was necessary to perform dehydration ring closure imidization by heating for a long time. On the other hand, the high temperature heat treatment can form a polyimide protective film having sufficient reliability, but on the other hand, there is a problem that the electric / electronic material itself to be protected is thermally deteriorated.

As the low-coloring polyimide, a polyimide obtained by heat-treating a solution of a polyamic acid synthesized from biphenyltetracarboxylic acids and an SO ₂ diamine-containing compound is described in JP-A-62-7733. However, it takes 25 to form a highly reliable polyimide film.
It requires heat treatment at 0 ° C or higher. On the other hand, as a means for solving the problem of high temperature treatment, a composition (varnish) comprising a solvent solution of a solvent-soluble low-coloring polyimide is disclosed in Japanese Patent Laid-Open No. HEI-1.
-132632, JP-A-5-32894, and JP-B-5-72406.

However, these known techniques have solved the problem of high-temperature heat treatment, but in a varnish using N-methyl-2-pyrrolidone, which is a good solvent for polyimide, polymer precipitation due to moisture absorption does not occur. It is apt to occur and it is necessary to pay sufficient attention to the humidity control of the coating environment, which limits the process. On the other hand, when a cresol-based solvent is used, there is no problem due to moisture absorption, but deterioration of the working environment such as odor becomes a problem.

[0005]

SUMMARY OF THE INVENTION The object of the present invention is to solve the above-mentioned drawbacks of the prior art and to achieve a relatively low temperature (22).
Provided is a low temperature cure type polyamic acid composition capable of dehydration ring-closure imidization even at 0 ° C. or lower), and 200 ° C. or lower, and capable of forming a low-coloring polyimide film with less problems in the coating step. Is. Another object of the present invention is to provide a tough polyimide coating film having a relatively high molecular weight, low colorability and high reliability.

[0006]

That is, the present invention provides:
A composition obtained by dissolving a polyamic acid comprising the following amic acid units A and B in an organic polar solvent:

Embedded image

[Chemical 6] (However, R represents a divalent linear aliphatic hydrocarbon residue having 4 to 12 carbon atoms or a linear aliphatic oxa hydrocarbon residue, and A: B is 97: 3 to 70 in a molar ratio. : 30) The present invention relates to a polyamic acid composition comprising 0.005 to 10% by weight of a lactam with respect to the polyamic acid.

The present invention also provides a composition obtained by dissolving a polyamic acid having the following amic acid units A and B in an organic polar solvent,

Embedded image

Embedded image (However, R represents a divalent linear aliphatic hydrocarbon residue having 4 to 12 carbon atoms or a linear aliphatic oxa hydrocarbon residue, and A: B is 97: 3 to 70 in a molar ratio. : 30.) A low-colored polyimide film, which is obtained by heating, drying, and imidizing a polyamic acid composition containing 0.005 to 10% by weight of lactam with respect to the polyamic acid. It is a thing.

The polyamic acid composition of the present invention preferably comprises biphenyltetracarboxylic dianhydride, bis (aminophenoxyphenyl) sulfone and the formula H ₂ N—R—N.
A mixture of diamines represented by H ₂ (R is a divalent linear aliphatic hydrocarbon residue having 4 to 12 carbon atoms or a divalent linear oxa hydrocarbon residue) is treated with an organic polar compound. It can be obtained by reacting in a solvent to form a polyamic acid and adding a lactam to the polyamic acid.

The diamine represented by the formula: H ₂ N—R—NH ₂ must be 3 to 30 mol%, preferably 5 to 25 mol% of the total diamine components. When the ratio of the diamine component represented by the formula: H ₂ N—R—NH ₂ is less than 3 mol%, the resulting polyamic acid solution composition is slightly incomplete in ring-closing imidation after heat treatment and tends to leave a solvent. . When the proportion of the diamine component represented by the above formula: H ₂ N—R—NH ₂ is more than 30 mol%,
The glass transition temperature of the obtained polyimide is low and the heat resistance is impaired.

The total amount of tetracarboxylic dianhydride and diamines used is approximately 1: 1 (molar ratio). The reaction temperature is 0 to 100 ° C., preferably 50 to 80 ° C., and the polymer concentration is 5 to 40% by weight.

In the present invention, it is essential to add a lactam to the polyamic acid solution, and the addition amount is 0.005 to the polymer (polyamic acid).
It is 10% by weight, preferably 0.01 to 5% by weight. By using an amount of lactam within the above range, the molecular weight of the resulting polyimide is increased (preferably,
The logarithmic viscosity can be 0.8 to 2.0), and it is possible to obtain a tough polyimide coating film having low coloring property and high reliability.

Examples of the biphenyltetracarboxylic dianhydride include 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride and 2,3,3', 4'-biphenyltetracarboxylic dianhydride. Either can be used. In addition, a part of these biphenyltetracarboxylic dianhydrides is pyromellitic dianhydride, 3,3 ′, 4,
4'-benzophenone tetracarboxylic dianhydride, naphthalene-1,4,5,8-tetracarboxylic dianhydride,
It can be replaced with naphthalene-2,3,6,7-tetracarboxylic dianhydride, 3,3 ′, 4,4′-diphenylethertetracarboxylic dianhydride and the like. In this case, the amount of these used is 20 mol% or less, preferably 1
The amount of 0 mol% or less is suitable.

Examples of the bis (aminophenoxyphenyl) sulfone include 4,4'-bis (4-aminophenoxy) diphenyl sulfone, 4,4'-bis (3-aminophenoxy) diphenyl sulfone and 3,3'-bis. (4
-Aminophenoxy) diphenyl sulfone. These can be used alone or in combination.

The diamine represented by the above formula: H ₂ N—R—NH ₂ includes 1,4-diaminobutane and 1,6-diamine.
Diaminohexane, 1,8-diaminooctane, 1,1
0-diaminodecane, 1,12-diaminododecane,
4,7-Dioxadecane-1,10-diamine, 4,9
-Dioxadodecane-1,12-diamine, 4,7,1
Examples thereof include 0-trioxatridecane-1,13-diamine. These can be used alone or in combination. Also, a part of the mixture of these diamines is added to 4,4 '
-Diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 1,4-bis (3-aminophenoxy) benzene, 1,3 -Bis (3-aminophenoxy) benzene, 4,4'-bis (3-aminophenoxy) diphenylpropane, 4,
It can be used by replacing it with an aromatic diamine such as 4′-bis (3-aminophenoxy) diphenyl.
When used by substituting, the amount used is preferably 10 mol% or less.

The acid dianhydride and the diamine are approximately equimolar,
Although a polyamic acid solution can be obtained by polymerizing in an organic polar solvent, a small amount of a monofunctional monomer can be used for the purpose of adjusting the polymerization degree of the polyamic acid. Examples of monofunctional monomers include maleic anhydride, succinic anhydride, phthalic anhydride, nadic acid anhydride, aniline and alkylamines.

The organic polar solvent used for the polymerization includes
Examples thereof include N, N-dimethylformamide, dimethyl sulfoxide, N, N-dimethylacetamide, N, N-diethylacetamide, N-methyl-2-pyrrolidone and the like, or a mixed solvent thereof. Particularly, N, N-dimethylacetamide and N-methyl-2-pyrrolidone are preferable.

The lactam to be added to the polyamic acid solution in the present invention includes β-propiolactam, γ-butyrolactam, γ-valerolactam, δ-valerolactam,
ε-caprolactam and the like can be mentioned. Particularly, ε-caprolactam is preferable. These lactams are usually added to the polyamic acid polymerization solution, but they can also be added at the initial or intermediate stage of the polymerization.

The polyamic acid composition of the present invention is uniformly applied, for example, to the surface of an object to be coated (circuit board, optical sensor, etc.) at room temperature or under heating by using a spin coater or a printer. It is possible to produce a transparent and solidified polyimide solidified film by applying a uniform thickness and then drying and imidizing the applied film at a temperature of preferably about 50 to 220 ° C.

The polyamic acid composition of the present invention can be adjusted in concentration, viscosity and the like depending on the film thickness to be coated, the characteristics of the coating machine and the like. Regarding the concentration adjustment, in addition to the above-mentioned polymerization solvent, xylene, ethyl cellosolve, diglyme, dioxane and methanol, ethanol, n-propanol, iso-propanol, in addition to the above-mentioned polymerization solvent, n-butanol, sec-butanol, n
A poor solvent for polyamic acid such as alcohols such as amyl alcohol, n-hexanol, and n-heptanol may be used. The viscosity of the polyamic acid composition has a correlation with both the polymer concentration and the molecular weight, but even at the same concentration, depending on the molar balance between the diamine and the tetracarboxylic dianhydride, and the use of monofunctional monomers. It can be adjusted.

The polyamic acid composition of the present invention comprises 22
Even at a relatively low heat treatment temperature of 0 ° C. or less, a solidified film that is almost 100% imidized can be obtained, and the obtained polyimide has a high molecular weight and is a highly reliable and tough film. 30
Relatively long time of about a minute (3 ~
It is possible to obtain a polyimide film that can sufficiently withstand a temperature of about 200 ° C. by a heat treatment of about 5 minutes). In particular, a film having a thickness of 20 μm or less, particularly about 0.1 to 10 μm has little coloring and is substantially transparent.

[0021]

EXAMPLES Examples of the present invention will be shown below.

Example 1 Internal volume of 200 m equipped with a stirrer and a nitrogen gas inlet / outlet pipe
1 N, N-dimethylacetamide 53.l in a reaction vessel.
In 2 g, 4.962 g (0.016 mol) of 4,4′-bis (3-aminophenoxy) diphenyl sulfone and 0.465 g (0.004 mol) of 1,6-diaminohexane were stirred while flowing a nitrogen gas. After the solution was added to the bottom and uniformly dissolved, 5.884 g (0.020 mol) of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride was gradually added. The solution was maintained at a reaction temperature of 70 ° C. for 3 hours to carry out polymerization to obtain a slightly yellow viscous polyamic acid solution. This solution was divided into two equal parts, and ε-caprolactam was added to one of them in a proportion of 0.15% by weight based on the polymer to prepare a polyamic acid composition of the present invention.

The composition prepared as described above was applied onto a SiO ₂ coated glass treated with a silane coupling agent (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) using a spin coater, 80 ° C x 10 minutes, 140 ° C x 10
Then, a heat treatment was performed at 200 ° C. for 30 minutes, to form a polyimide thin film having a thickness of about 5 μm. About this thin film, a self-recording spectrophotometer (manufactured by Hitachi, Ltd., 330
400) with the same type of SiO ₂ coated glass
The difference in light transmittance between the light beams having wavelengths of nm and 450 nm was measured. In addition, for this thin film, the pressure cooker
Test (PCT) (conditions: 121 ° C, 2 atmospheric pressure steam, 2
0 hours) to change appearance and cross-cut peeling test [J
IS K-5400 cross-cut test method] was performed to examine the adhesiveness.

Further, the above composition was uniformly applied on a degreased and washed aluminum plate using an applicator, and then 80 ° C. × 10 minutes, 140 ° C. × 10 minutes, 200 ° C.
A heat treatment for 30 minutes was performed to form a polyimide thin film having a thickness of about 5 μm. About this thin film, 180 ° bending test before and after the pressure cooker test [JIS K
-5400 Flex resistance test method] was performed to examine the change in film strength.

Finally, after applying the above composition uniformly on a glass plate using an applicator, heat treatment is carried out at 80 ° C. × 10 minutes, 140 ° C. × 10 minutes, 200 ° C. × 30 minutes, A polyimide thin film having a thickness of about 10 μm was formed. Then, the thin film was peeled off from the glass plate, and the thin film had a logarithmic viscosity ηinh [concentration: 0.5 g / 100 ml solvent: N-methyl-2-pyrrolidone, measurement temperature: 30 ° C.]
Was measured by the following formula. ηinh (dl / g) = ln (t / t ₀ ) / ct ₀ : Time for N-methyl-2-pyrrolidone to drop in the viscosity tube t: Time for sample solution to drop in the viscosity tube c: Sample concentration The results are summarized in Table 1. Further, this polyimide (film) has a Tg (glass transition temperature) of 225 ° C.,
Td ^3% (thermogravimetric analysis: temperature showing 3% weight loss in TGA) was 490 ° C.

Comparative Example 1 Example 1 was repeated except that ε-caprolactam was not added to the other half of the polyamic acid solution obtained in Example 1.
Was performed in the same manner as described above. The results are summarized in Table 1.

Example 2 In place of 4,4'-bis (3-aminophenoxy) diphenyl sulfone, 6.962 g (0.016 mol) of 4,4'-bis (4-aminophenoxy) diphenyl sulfone and 3 5,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, instead of 5,3,3 ′, 4′-biphenyltetracarboxylic dianhydride, 5.884 g (0.020
Mol) was used, and the same procedure as in Example 1 was carried out. The results are summarized in Table 1. Also, the obtained polyimide (film)
Has a Tg (glass transition temperature) of 235 ° C. and a Td of ^3%
(Thermogravimetric analysis: temperature showing 3% weight loss in TGA) was 490 ° C.

Comparative Example 2 The amount of 4,4'-bis (3-aminophenoxy) diphenyl sulfone was changed from 6.962 g (0.016 mol) to 8.
The procedure of Example 1 was repeated except that 1,650-diaminohexane was not used instead of 650 g (0.020 mol). Table 1 shows the results.

Example 3 The amount of 4,4'-bis (3-aminophenoxy) diphenyl sulfone was changed from 6.962 g (0.016 mol) to 8.
To 267 g (0.019 mol), the amount of 1,6-diaminohexane was 0.465 g (0.004 mol) to 0.1.
The same procedure as in Example 1 was performed except that the amount was changed to 16 g (0.001 mol). The results are summarized in Table 1. The obtained polyimide (film) has a Tg (glass transition temperature) of 2
The temperature was 45 ° C, and the Td ^3% (thermogravimetric analysis: temperature at which 3% weight loss was observed in TGA) was 495 ° C.

[0030]

[Table 1]

[0031]

Since the present invention is configured as described above, the following effects can be obtained.

The polyamic acid composition of the present invention can be dehydrated and ring-closed imidized at a relatively low temperature (220 ° C. or lower), and can form a low-coloring polyimide film with few problems in the coating process. .

Further, the polyimide film of the present invention has a high molecular weight, low coloring property, high light transmittance, and toughness.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location H01B 3/30 H01B 3/30

Claims (2)

[Claims] 1. A composition comprising a polyamic acid comprising the following amic acid units A and B dissolved in an organic polar solvent, wherein: Embedded image (However, R represents a divalent linear aliphatic hydrocarbon residue having 4 to 12 carbon atoms or a linear aliphatic oxa hydrocarbon residue, and A: B is 97: 3 to 70 in a molar ratio. : 30.) A polyamic acid composition comprising 0.005 to 10% by weight of a lactam with respect to the polyamic acid. 2. A composition obtained by dissolving a polyamic acid comprising the following amic acid units A and B in an organic polar solvent, wherein: Embedded image (However, R represents a divalent linear aliphatic hydrocarbon residue having 4 to 12 carbon atoms or a linear aliphatic oxa hydrocarbon residue, and A: B is 97: 3 to 70 in a molar ratio. : 30.) A low-colored polyimide film, which is obtained by heating, drying, and imidizing a polyamic acid composition containing 0.005 to 10% by weight of a lactam with respect to the polyamic acid.