JPH05255499A - Production of polyimide precursor - Google Patents

Abstract

PURPOSE:To obtain the subject precursor with sufficient molecular weight and mechanical viscosity favorable in workability even after short-time reaction, good in storage stability, by reaction of a tetracarboxylic acid dianhydride with a diamine compound such as a bis(aminophenoxy)benzene under specified conditions. CONSTITUTION:The objective polyimide precursor having the above-mentioned advantages can be obtained by reaction of (A) a tetracarboxylic acid dianhydride of formula I (R is tetravalent group consisting of e.g. non-condensed polycyclic aromatic group with >=2C aliphatic group, alicyclic group, monocyclic aromatic group, condensed polycyclic aromatic group, or aromatic group linked mutually either directly or through a crosslinking member) (e.g. pyromellitic dianhydride) with (B) a diamine compound of formula II (two ether links are situated mutually at para-site or meta-site relatively to the central benzene ring, and the amino groups at both ends are situated at para-site or meta-site relatively to the ether links) [e.g. 1,3-bis(3-aminophenoxy)benzene] at 40-100 deg.C.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a polyimide precursor. More specifically, it relates to a method for producing a polyimide precursor having good storage stability.

[0002]

2. Description of the Related Art Conventionally, a polyimide obtained by a reaction of a tetracarboxylic dianhydride and / or its derivative with a diamine compound has high heat resistance, mechanical strength, dimensional stability, flame retardancy, and electrical resistance. It has excellent insulation properties,
It is used in fields such as electronic equipment, aerospace equipment, and transportation equipment, and is expected to be widely used in fields where heat resistance is required in the future.

Conventionally, once polyimide is imidized, it does not dissolve in an ordinary organic solvent, and even if it is heated, its melting point is close to the decomposition temperature of the polymer, so that it cannot be melt-molded. . Therefore, when using the polyimide, for example, when used as an electric wire varnish, a coverlay or an adhesive, it is dissolved in an organic solvent in the state of the polyamic acid which is the precursor of the polyimide, and this is applied onto the object to be coated. After that, a method of removing the solvent and imidizing by heat treatment at a high temperature is adopted. Further, also in the production of a film, for example, a method of casting a polyamic acid solution on a steel belt and subjecting it to heat treatment at a high temperature for desolvation and imidization is adopted.

The final polyimide has sufficient mechanical strength,
In order to have excellent electric properties and the like, the precursor thereof, that is, the polyamic acid must have a sufficiently large molecular weight. For example, the following formula (3)

[0005]

[Chemical 3]

In the case of the polyamic acid represented by the repeating unit of, in order for the final polyimide to have satisfactory physical properties,
It is said that the logarithmic viscosity (concentration of 0.5 g / 100 ml solvent in N-methyl-2-pyrrolidone solvent, measured at 35 ° C.) is 0.5 or more, preferably 0.8 to 1.5.

For this reason, diamine is usually dissolved in an organic solvent and tetracarboxylic dianhydride is gradually added at a low temperature (5 ° C. to 30 ° C.) to prepare a polyamic acid having a desired molecular weight ( U.S. Pat. No. 4,065,345).

However, such a high molecular weight polyamic acid solution in an organic solvent has a problem that the mechanical viscosity is high and coating is difficult. Further, even if the polyamic acid varnish had a high molecular weight immediately after it was formed, if it was stored at 20 to 30 ° C., the molecular weight and the mechanical viscosity gradually decreased, and it was difficult to perform the treatment under constant processing conditions.

As a method of lowering the mechanical viscosity and facilitating the handling, for example, a highly viscous polyamic acid varnish is once produced at a low temperature and then at a high temperature (80 to 85 ° C.).
A method of processing is presented (Polyimdes)
K. L. Mittal, vol. 1, p. 259).

However, once a high-viscosity varnish is used, it takes a lot of time to reduce it to a desired mechanical viscosity even if it is treated at a high temperature, which is not an efficient method. Further, even if the mechanical viscosity is once lowered, if the equilibrium point is not reached, the mechanical viscosity may increase or decrease during storage for a long time, which causes a problem in storage stability.

On the other hand, as a method for improving the storage stability of a polyamic acid varnish, JP-A-3-259923 discloses that tetracarboxylic acid dianhydride is reacted with alcohol in the presence of an amine catalyst such as pyridine to give tetracarboxylic acid. A method is disclosed in which an acid diester is prepared and then reacted with a diamine compound. However, in this method, if the amine-based catalyst remains, the storage stability of the varnish is significantly reduced, and therefore the catalyst needs to be removed. Therefore, the patent proposes a method of adding a cation exchange resin and removing the catalyst after adjusting the varnish, but it takes 20 hours to remove the catalyst, and a filtration step for removing the ion exchange resin is required. ..

[0012]

DISCLOSURE OF THE INVENTION The present invention provides a polyimide precursor having a sufficient molecular weight, a mechanical viscosity suitable for workability and a good storage stability, and a method for producing the same. is there.

[0013]

[Means for Solving the Problems] The inventors of the present invention have conducted intensive studies to solve the above problems and completed the present invention. That is, the present invention is represented by the general formula (1)

[0014]

[Chemical 4]

[In the formula, R represents an aliphatic group having 2 or more carbon atoms, a cycloaliphatic group, a monocyclic aromatic group, a condensed polycyclic aromatic group, or an aromatic group, either directly or by a crosslinking member. It represents a tetravalent group selected from the group consisting of linked non-fused polycyclic aromatic groups. ] One or more types of tetracarboxylic acid dianhydride shown in these,
General formula (2) (chemical formula 5)

[0016]

[Chemical 5]

[In the formula, two ether bonds occupy para-position or meta-position with respect to the central benzene ring, and amino groups at both ends occupy para-position or meta-position with respect to the ether bond. ] In the method of producing a polyimide precursor by reacting with one or more diamine compounds represented by the above, the production reaction is carried out at 40 ° C to 100 ° C.

A feature of the present invention is to obtain a polyimide precursor solution having a sufficient molecular weight and good workability in a short time by carrying out the reaction for forming a polyimide precursor at 40 ° C. to 100 ° C. The tetracarboxylic dianhydride used in the present invention has the general formula (1)

[0019]

[Chemical 6]

[Wherein R is the same as before. ]

Examples thereof include ethylene tetracarboxylic dianhydride, butane tetracarboxylic dianhydride, cyclopentane tetracarboxylic dianhydride, pyromellitic dianhydride, 1,1-bis (2 , 3-Dicarboxyphenyl) ethane dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, 2,2-bis (3,3 4-dicarboxyphenyl) propane dianhydride,
2,2-bis (2,3-dicarboxyphenyl) propane dianhydride, 2,2-bis (3,4-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropanedi Anhydrous, 2,2-bis (2,3-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride, 3,3 ', 4,4'-benzophenone tetracarboxylic Acid dianhydride, 2,2 ', 3,3'-benzophenone tetracarboxylic acid dianhydride, 3,3', 4
4'-biphenyltetracarboxylic dianhydride, 2,
2 ', 3,3'-biphenyltetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, bis (2,3-dicarboxyphenyl) ether dianhydride, bis (3,3 4-dicarboxyphenyl) sulfone dianhydride, (4,4′-p-phenylenedioxy) diphthalic acid dianhydride, (4,4′-m-phenylenedioxy) diphthalic acid dianhydride, 2,3 , 6,7-Naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 1,2,5,6-
Naphthalenetetracarboxylic dianhydride, 1,2,3,4
-Benzenetetracarboxylic dianhydride, 3,4,9,1
0-perylene tetracarboxylic dianhydride, 2, 3, 6,
7-anthracene tetracarboxylic dianhydride, 1,2,
7,8-phenanthrenetetracarboxylic dianhydride and the like, and these tetracarboxylic dianhydrides may be used alone or in combination of two or more. The diamines to be reacted with the tetracarboxylic dianhydride are represented by the general formula (2)

[0022]

[Chemical 7]

[In the formula, two ether bonds occupy para-position or meta-position with respect to the central benzene ring, and amino groups at both ends occupy para-position or meta-position with respect to the ether bond. ] It is a diamine shown by these, and in this invention, 1 or more types are used.

Specifically, 1,3-bis (3-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (3-aminophenoxy) benzene, 1,4 -Bis (4-aminophenoxy)
Examples thereof include benzene, which may be used alone or in combination of two or more.

In the present invention, tetracarboxylic dianhydride and diamine are reacted in an organic solvent to obtain a solution of a polyimide precursor in an organic solvent. Further, in the present invention, there is no problem even if a part of the polyimide obtained by dehydration ring closure of the polyimide precursor is contained in the organic solvent solution of the polyimide precursor.

Examples of the organic solvent used in the present invention include N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylacetamide,
N, N-dimethylmethoxyacetamide, N-methyl-
2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, N-methylcaprolactam, 1,3-dimethoxyethane, bis (2-methoxyethyl) ether, 1,2
-Bis (2-methoxyethoxy) ethane, tetrahydrofuran, 1,4-dioxane, pyridines, picolines, quinolines, dimethyl sulfoxide, dimethyl sulfone, tetramethylurea, hexemethylphosphoramide, phenol, m-cresol, p-cresol, o
-Cresol, m-chlorophenol, p-chlorophenol, o-chlorophenol, anisole, etc. may be mentioned, and these may be used alone or in combination.

The reaction temperature varies depending on the diamine, the tetracarboxylic dianhydride and the solvent used in the reaction, but is 40
-100 ° C, preferably 60-80 ° C. If the reaction temperature is too low, it takes time to reach the desired constant mechanical viscosity, which is not efficient. In addition, a change in viscosity occurs during storage and the stability decreases. When the reaction temperature is too high, imidization proceeds too much, water generated by dehydration ring closure causes hydrolysis of the polyimide precursor, and changes in viscosity during storage occur.
Therefore, the reaction to generate the polyimide precursor is 40 to 100 ° C.
It is done in the range of.

The reaction pressure is not particularly limited and can be carried out at normal pressure. The reaction time varies depending on the diamine, the tetracarboxylic dianhydride, the solvent used in the reaction, and the reaction temperature, but it is carried out until the formation of the polyimide precursor is completed and the viscosity does not change over time. Usually 30 minutes to 1
0 hours is sufficient.

The polyimide precursor thus obtained can be used in various fields such as a film, an electric wire varnish, a coverlay, a coating material, an adhesive agent, or a composite material by impregnating a fibrous reinforcing material. ..
At that time, the polyimide precursor is further heated to 100 to 300 ° C., or is subjected to ring-closing imidization with a dehydrating agent such as acetic anhydride to be used.

[0030]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples. Example 1 292.3 g of 1,3-bis (3-aminophenoxy) benzene in a container equipped with a reflux condenser and a nitrogen introducing tube.
(1.0 mol) and N-methyl-2-pyrrolidone 2030
g was charged and the temperature was raised to 40 ° C. to dissolve the diamine. 214.3 g of pyromellitic dianhydride under nitrogen atmosphere
(0.9825 mol) was added at once and stirring was continued. Solution temperature is 60 ℃ by addition of pyromellitic dianhydride
Rose to. The temperature was kept at 60 to 65 ° C. and stirring was continued for 30 minutes, and the mechanical viscosity was measured to be 13,000 centipoise (25 ° C., measured with an E-type viscometer; the same applies hereinafter) and logarithmic viscosity (N-methyl-2-pyrrolidone). 3 at 0.5% concentration
The measurement was made at 5 ° C., and the same hereinafter) was 0.72 dl / g.

When the mechanical viscosity was measured by further stirring for 30 minutes, it was 13,000 centipoise and the logarithmic viscosity was 0.72 dl / g, and there was no change at all. This polyimide precursor solution was stored at 25 to 30 ° C., and mechanical viscosity and logarithmic viscosity were measured at any time, and the results shown in Table 1 were obtained.

[0032]

[Table 1]

It can be seen that the polyimide precursor solution can be prepared in a short time and the storage stability is extremely good.

Comparative Example 1 292.3 g (1.0 mol) of 1,3-bis (3-aminophenoxy) benzene and N were placed in the same reaction vessel as in Example 1.
-Methyl-2-pyrrolidone (2030 g) was charged, and the mixture was cooled to around 5 ° C and pyromellitic dianhydride (174.5 g) was added.
(0.8 mol) was added in four portions every 30 minutes so that the solution temperature did not rise above 20 ° C., and then the mixture was stirred at about 5 ° C. for about 2 hours. Then, the above solution is returned to room temperature (25 ° C.) and pyromellitic dianhydride 3 is added under a nitrogen atmosphere.
6.7 g (0.182 mol) was added, and after 30 minutes, the mechanical viscosity was measured and found to be 83,000 centipoise. After that, when the mechanical viscosity was measured every 30 minutes, it was 7
5,000, 68,000, 65,000 centipoise and decreases with time, and after 12 hours mechanical viscosity 44.0
The viscosity was 00 centipoise and the inherent viscosity was 0.96 dl / g. Furthermore, under a nitrogen atmosphere, pyromellitic dianhydride 0.1
1 g (0.0005 mol) was added and stirred for 20 hours, mechanical viscosity 46,000 centipoise, logarithmic viscosity 0.97 dl
/ G of polyimide precursor was obtained. This precursor had a high viscosity, and coating and casting were very difficult. Therefore, the viscosity was reduced by heating the polyimide precursor solution. Polyimide precursor solution at 60-65 ° C
Hold, and measure the mechanical viscosity and logarithmic viscosity at regular intervals,
The results shown in Table 2 were obtained.

[0035]

[Table 2]

Further, this polyimide precursor solution is added to 25 to 3
Store at 0 ° C, measure mechanical viscosity and logarithmic viscosity at any time, and
Got the result.

[0037]

[Table 3]

As compared with Example 1, it took a long time to prepare a polyimide precursor solution having a desired viscosity, and the storage stability was inferior to that of Example 1.

Example 2 292.3 g (1.0 mol) of 1,3-bis (3-aminophenoxy) benzene and N were placed in the same reaction vessel as in Example 1.
-Methyl-2-pyrrolidone 2439 g was charged, and 45 ° C
The temperature was raised to and the diamine was dissolved. Then, under a nitrogen atmosphere, 317.4 g (0.985 mol) of 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride was added all at once. The solution temperature rose to 62 ° C. Temperature is 60 ~ 65 ℃
The mechanical viscosity and the logarithmic viscosity were measured every 30 minutes, and the results shown in Table 4 were obtained.

[0040]

[Table 4]

Further, this polyimide precursor solution is added to 20 to 2
The sample was stored at 5 ° C., and changes in mechanical viscosity and logarithmic viscosity with time were measured at any time, and the results shown in Table 5 were obtained.

[0042]

[Table 5]

Example 3 A reactor similar to that used in Example 1 was charged with 292.3 g (1.0 mol) of 1,4-bis (3-aminophenoxy) benzene and 2330 g of N, N-dimethylacetamide, and 4
The temperature was raised to 0 ° C. and the diamine was dissolved. Then, under nitrogen atmosphere, 290 g (0.987 mol) of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride was added all at once, and the solution temperature was kept at 60 to 65 ° C. and stirring was continued. .. Three
After adding 3 ', 4,4'-biphenyltetracarboxylic dianhydride, the mechanical viscosity and the logarithmic viscosity were measured every 30 minutes, and the results shown in Table 6 were obtained.

[0044]

[Table 6]

This solution was stored at 25 to 30 ° C., and changes with time of mechanical viscosity and logarithmic viscosity were examined, and the results shown in Table 7 were obtained.

[0046]

[Table 7]

Comparative Example 2 As in Example 3, except that the reaction temperature was 25 to 30 ° C. and the 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride was divided over about 10 hours. This was added to obtain a polyimide precursor having a mechanical viscosity of 10,000 centipoise and a logarithmic viscosity of 0.92. In order to synthesize the polyimide precursor having the above-mentioned viscosity, 288 g (0.98 mol) of 3,
Requires 3 ', 4,4'-biphenyltetracarboxylic dianhydride. Add this polyimide precursor varnish to 25-30 ° C.
The sample was stored in a container and the changes in mechanical viscosity and logarithmic viscosity with time were examined. The results are shown in Table 8.

[0048]

[Table 8]

Both mechanical viscosity and logarithmic viscosity decrease during storage,
It was inferior in storage stability.

[0050]

According to the method of the present invention, it is possible to obtain a polyimide precursor solution having a sufficient molecular weight, a good workability and a good mechanical viscosity, and a good storage stability in a short time.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Eiji Segami Inoue 30 Mitsui Toatsu Chemical Co., Ltd., Omuta City, Fukuoka Prefecture (72) Inventor Osamu Yasui 30 Mitsui Toatsu Chemical Co., Ltd. Asamu Town, Omuta City, Fukuoka Prefecture (72) Inventor Ikki Yoshida 30 Mitsui Toatsu Chemical Co., Ltd., Asmuta-cho, Omuta-shi, Fukuoka (72) Inventor Akinori Ryu 30 Asamuta-cho, Omuta-shi, Fukuoka Mitsui Toatsu Chemical Co., Ltd.

Claims (1)

[Claims] 1. General formula (1) (Chemical formula 1) [In the formula, R is an aliphatic group having 2 or more carbon atoms, a cycloaliphatic group,
Represents a tetravalent group selected from the group consisting of a monocyclic aromatic group, a condensed polycyclic aromatic group, and a non-condensed polycyclic aromatic group in which aromatic groups are connected to each other directly or by a crosslinking member. .. ] One or more types of tetracarboxylic acid dianhydride shown by these and general formula (2)
(Chemical formula 2) [Chemical formula 2] [In the formula, two ether bonds occupy para-position or meta-position with respect to the central benzene ring, and amino groups at both ends occupy para-position or meta-position with respect to the ether bond. ] In the method of producing a polyimide precursor by reacting with one or more diamine compounds represented by
A method for producing a polyimide precursor, which is performed at 100 ° C.