JPH08120077A - Production of polyimide precursor powder - Google Patents

Abstract

PURPOSE: To obtain a polyimide precursor powder by a simple process in which a suspension having a high polyimide precursor content can be obtained using a water-soluble ketone as a solvent. CONSTITUTION: A tetracarboxylic dianhydride is dispersed or dissolved in a water-soluble ketone. A diamine is added thereto to polymerize the anhydride and the diamine to obtain a dispersion having a polyimide precursor content of at least 10wt.%. The solvent is then removed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polyimide precursor powder. More specifically, a water-soluble ketone is used as a polymerization solvent to efficiently obtain a polyimide precursor powder having a high degree of polymerization. The present invention relates to a method for producing a polyimide precursor powder that can be used.

[0002]

2. Description of the Related Art Conventionally, polyimide precursors are N, N-dimethylformamide, N-methyl-2-pyrrolidone, hexamethylphosphoramide, N-methylcaprolactam, dimethylsulfoxide, N-acetyl-2-pyrrolidone and N. , N-dimethylacetamide and the like are strongly solvated with a polyamic acid, that is, a method of polymerizing in a so-called aprotic amide polar solvent.

According to these methods, the polyimide precursor is obtained in a state of being dissolved in a solvent. Therefore, in order to obtain a polyimide precursor powder or a polyimide powder from a solution of these polyimide precursors, it was obtained as follows. That is, JP-B-39-22196, JP-B-39-30060 and JP-A-60-22142.
5, JP-A 61-234, JP-A 61-2
In Japanese Patent No. 50030 and Japanese Patent Laid-Open No. 2-18420,
Aprotic amide polar solvent solution of the polyimide precursor, acetone, a poor solvent such as ethyl acetate and acetic anhydride, a method of obtaining a polyimide powder by ring closure of the polyimide precursor, or polyimide There is disclosed a method of obtaining a polyimide precursor powder by mixing an aprotic amide polar solution of a precursor with acetone or a halogenated hydrocarbon.

In any of these manufacturing methods,
Although the target polyimide precursor powder or polyimide powder is obtained from the solution of the aprotic amide polar solvent of the polyimide precursor, since the aprotic amide polar solvent and the polyimide precursor are strongly solvated. , To isolate the desired powder from this polyimide precursor solution,
Not only a complicated operation is required, but also the aprotic amide polar solvent is likely to remain in the obtained powder, which is not necessarily a useful production method from an industrial point of view.

As a method for solving these problems,
The following literature describes a method of producing a polyimide precursor powder by polymerizing a tetracarboxylic dianhydride and a diamine using a solvent having a low boiling point such as tetrahydrofuran and which is easy to remove the solvent. (Journal Polymer Science [J.Appl.Polymer Sci.,] Vol. 11
609-627, 1967). According to this method, a polyimide precursor powder containing no aprotic amide polar solvent that strongly solvates with the polyimide precursor can be obtained. However, the concentration of the polyimide precursor suspension obtained by this method is at most about 10%, which is not necessarily a useful method industrially.

[0006]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to obtain a polyimide precursor powder without using an aprotic amide polar solvent and without a complicated production process. It is to provide a method for producing a precursor powder.

[0007]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have dissolved or dispersed tetracarboxylic dianhydride in a water-soluble ketone,
The inventors have obtained the finding that a suspension having a high content of polyimide precursor powder can be obtained by adding a diamine powder thereto, and the present invention has been accomplished based on such finding.

That is, the gist of the present invention is to disperse or dissolve a tetracarboxylic acid dianhydride in a water-soluble ketone, and add a diamine to polymerize the tetracarboxylic acid dianhydride and the diamine to obtain a polyimide precursor. At least one body
A method for producing a polyimide precursor powder, which comprises forming a suspension containing 0% by weight and removing a solvent.

The present invention will be described in detail below. In the present invention, the polyimide precursor is closed by heating or chemical action to form a polyimide, and 60 mol% or more, preferably 70 mol% or more, more preferably 80 mol% or more of the repeating unit of the polymer chain has a polyimide structure. It refers to an organic polymer, and any one may be used as long as it has a ring closure rate of less than 60% of the polyimide structure and 100% ring closure results in a non-thermoplastic polyimide. As a method for 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, but a method by heating is preferable since it is simple.

The preferred polyimide precursor in the present invention is a wholly aromatic polyimide precursor, and particularly preferred is a homopolymer or copolymer of an aromatic polyamic acid having a repeating unit represented by the general formula (1). However, the compound represented by the general formula (1) is an unclosed ring.

[0011]

Embedded image

[0012] Here, R represents a tetravalent aromatic residue containing at least one 6-membered carbon ring, and each of the 4 valents forms a pair, and each of the 4 valences forms a pair. Are bound to. Specific examples of R include the following.

[0013]

Embedded image

Particularly, R is preferably the following.

[0015]

Embedded image

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

[0017]

[Chemical 4]

[0018]

Embedded image

Further, the following are particularly preferable as R '.

[0020]

[Chemical 6]

In the present invention, tetracarboxylic dianhydride is dispersed or dissolved in water-soluble ketone, and then diamine is added to polymerize. Examples of the water-soluble ketone that is a solvent for polymerization include acetone and methyl ethyl ketone, with acetone being preferred. Further, another solvent can be mixed within a range that does not impair the effects of the present invention.

The present invention is characterized in that the diamine is added as it is to the dispersion or solution of the tetracarboxylic dianhydride. The polymerization reaction proceeds at the solid-liquid interface of the added diamine, and the polyimide precursor produced is deposited outside the reaction system, so the amount of the polymerization solvent is sufficient to disperse this. By this method, a polyimide precursor powder having a high degree of polymerization can be obtained more efficiently than in the conventional method.

The diamine is preferably added with stirring. Particularly, it is preferable to uniformly disperse the monomer particles in order to deposit the polyimide precursor having a high degree of polymerization. And, it is sufficient to achieve the object of the present invention if the stirring force is sufficient to uniformly disperse the monomer particles,
It is considered that the rate-determining step of the polymerization reaction is the transition from the solid phase of the diamine to the liquid phase interface, and if the polyimide precursor particles produced at this interface are successively removed, the polymerization reaction proceeds smoothly. Further, the particle size (surface area) of the added diamine particles is also related to the polymerization reaction. The smaller the particle size of the diamine particles (the larger the surface area), the more the number of reaction sites,
It is considered that the polymerization reaction proceeds smoothly. Therefore, for example, by reacting while crushing the monomer in a mixer having a high shearing force, or in a rotary reactor containing a crushing ball, the above object is achieved,
The reaction time can be shortened and the degree of polymerization of the polyimide precursor produced tends to increase.

In the present invention, the reaction temperature is not required to be strictly controlled, but it is -20 to 50 ° C., especially 0 to 30.
C. is preferred. The reaction time depends on the particle size of the diamine particles and the like, but is 1 to 20 hours, especially 3 to 10 hours.
Time is preferred. Further, as is known, the charging ratio of tetracarboxylic dianhydride and diamine is correlated with the degree of polymerization of the polyimide precursor to be produced, and to obtain a polyimide precursor having a high degree of polymerization, tetracarboxylic dianhydride and It is preferable to charge the diamine in the vicinity of the equimolar amount.

The resulting polyimide precursor is not dissolved in the solvent used, but is in a suspended state in the solvent, and has a content of at least 10% by weight, usually 10 to 25% by weight. Therefore, the solvent is removed by a usual method such as filtration and drying to obtain a polyimide precursor powder. At this time, since a solvent that does not strongly interact with the polyimide precursor is used as the solvent, it is easy to remove the solvent and a powder of the polyimide precursor containing no solvent can be easily obtained.

At this time, the stability of the polyimide precursor with time can be maintained by not completely removing the solvent or by mixing the polyimide precursor powder again with the solvent and storing the mixture in this state. That is, in a suspension composed of the polyimide precursor powder and the water-soluble ketone, the stability of the polyimide precursor powder with time is maintained.

The intrinsic viscosity [η] of the polyimide precursor powder obtained according to the present invention is preferably 0.3 or more, particularly preferably 0.5 or more. If [η] is less than 0.3, the properties of the obtained product tend to deteriorate, which is not preferable. In addition,
[Η] is a value directly related to the molecular weight of the polymer, and N,
It is measured at 30 ° C. in a N-dimethylacetamide solvent at a polyimide precursor concentration of 0.5% by weight. To calculate [η], by measuring the time for the polymer solution to flow through a fixed volume capillary of a standard viscometer and the time for which only the solvent flows,
It can be calculated using the following formula: Note that C is the polyimide precursor concentration.

[0028]

[Equation 1]

The polyimide precursor powder obtained according to the present invention is usually observed as an aggregate in which spherical particles of about 0.1 to 3 μm are aggregated to a higher degree. The particle size of this agglomerate can be adjusted to about 10 to 50 μm by undergoing a crushing step, but when used as a molding powder, the particle size is preferably 100 μm or less and 80% by weight or more. .

The polyimide precursor powder of the present invention can be formed into a polyimide molded product having good characteristics by a method generally called a sintering molding method. That is, the polyimide precursor powder can be compressed under conditions that do not cause imide ring closure to form a preform having a desired shape, and then imide ring closure can be performed in a firing furnace to obtain the desired polyimide form.

[0031]

The present invention will be described below in detail with reference to examples. The particle size of the powder was measured by laser diffraction particle size distribution measurement (LA-500 manufactured by Horiba Ltd.). Further, the bulk density of the powder is represented by a value obtained by measuring the weight of the powder when the powder was put through a funnel in a 100 ml container and cutting the weight, and dividing this by the volume of the container.

Example 1 In a flask, 14.5 g of pyromellitic dianhydride (PMDA) was dissolved in 250 g of acetone, and the mixture was stirred with a stirring device having one blade, and diaminodiphenyl ether ( 13.3 g of DADE) was continuously added over 3 minutes at room temperature (25 ° C.) and stirring was continued. After the addition was completed, stirring was continued for further 5 hours to obtain a white-yellow suspension. The suspension was suction filtered to obtain a white-yellow wet powder. This was dried in an evaporator under reduced pressure at 60 ° C. for 3 hours, crushed in a mortar, and vacuum dried at 120 ° C. for 3 hours to obtain a polyimide precursor powder.

Example 2 A polyimide precursor powder was obtained in the same manner as in Example 1 except that 23.6 g of PMDA and 21.7 g of DADE were used.

Example 3 A polyimide precursor powder was obtained in the same manner as in Example 1 except that 31.5 g of PMDA and 28.9 g of DADE were used.

Example 4 As in Example 1, 92.4 g of PMDA was dispersed in 930 g of acetone, and 84.8 g of DADE was added thereto over 15 minutes, and stirring was continued. The polyimide precursor started to precipitate in about 30 minutes, and stirring was continued for further 6 hours to obtain a polyimide precursor suspension. Further, a polyimide precursor powder was obtained in the same manner as in Example 1.

Example 5 Polymerization was carried out in the same manner as in Example 4, except that stirring was carried out using a disperser. At the same time as the addition of the diamine, the polyimide precursor began to precipitate, and high-speed stirring was continued for 1 hour to obtain a polyimide precursor suspension. further,
A polyimide precursor powder was obtained in the same manner as in Example 1.

Example 6 Acetone 250 was placed in a pot containing crushed balls of φ10 mm.
g and 31.5 g of PMDA were added and well dispersed, then 28.9 g of DADE were added stepwise in approximately equal amounts over 15 minutes while the pot was rotated on a pedestal with rollers. , Crushing and mixing were continued. Further DAD
After the addition of E, the rotation was continued for 3 hours to obtain a suspension of the polyimide precursor. A polyimide precursor powder was obtained in the same manner as in Example 1.

Example 7 37.6 g of PMDA was added to 300 in the same manner as in Example 1.
After being dispersed in 1 g of acetone, 18.5 g of para-phenylenediamine was added in the form of powder, and after addition, another 6
Stirring was continued over time. From the obtained polyimide precursor suspension, a polyimide precursor powder was obtained in the same manner as in Example 1.

Example 8 30.5 g of PMDA was added to 300 in the same manner as in Example 1.
After dispersing in g acetone, 40.6 g 1,4-bis (paraaminophenoxy) benzene was added and stirring was continued for another 5 hours after the addition. Polyimide precursor powder was obtained in the same manner as in Example 1 from the obtained polyimide precursor suspension.

Example 9 In the same manner as in Example 1, 42.8 g of biphenyltetracarboxylic dianhydride was dispersed in 300 g of acetone, and 28.0 g of DADE was added.
Stirring was continued over time. From the obtained polyimide precursor suspension, a polyimide precursor powder was obtained in the same manner as in Example 1.

Example 10 In the same manner as in Example 1, 46.3 g of benzophenonetetracarboxylic dianhydride was dispersed in 300 g of acetone, 28.7 g of DADE was added, and 3 hours after the addition. Stirring was continued. From the obtained polyimide precursor suspension, a polyimide precursor powder was obtained in the same manner as in Example 1.

Comparative Example 1 31.5 g was added to 28.9 g of an acetone dispersion of DADE.
A polyimide precursor powder was obtained in the same manner as in Example 1 except that PMDA was added, but [η] was 0.25.

Comparative Example 2 A polyimide precursor powder was obtained in the same manner as in Example 6 except that PMDA and DADE were reversed and added.
[Η] was 0.28.

[0044]

[Table 1]

[0045]

According to the production method of the present invention, a suspension having a high content of a polyimide precursor can be obtained, and since a water-soluble ketone is used as a solvent, a complicated production process is not required. A polyimide precursor powder can be obtained. The obtained polyimide precursor powder has a high degree of polymerization and does not contain an aprotic amide polar solvent.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Yoshiaki Iwaya 23 Uji Kozakura, Uji City, Kyoto Prefecture Unitika Ltd. Central Research Laboratory

Claims (1)

[Claims] 1. A tetracarboxylic dianhydride is dispersed or dissolved in a water-soluble ketone, a diamine is added to polymerize the tetracarboxylic dianhydride and the diamine, and at least 10% by weight of a polyimide precursor is added. A method for producing a polyimide precursor powder, which comprises forming a suspension containing the solvent and removing the solvent.