JPH01242622A - Polyimide powder - Google Patents

Abstract

PURPOSE:To make it possible to prevent nonuniformity of mixing and to obtain an excellent filling effect, by defining a mean particle diameter and a particle size distribution of a polyimide powder in a specified range and adjusting a logarithmic viscosity in a specified range by reducing the MW of the polyimide powder. CONSTITUTION:This polyimide powder has a mean particle diameter of 1-20mum, a particle size distribution of 0.1-50mum and a logarithmic viscosity of 0.1-0.5 (at 30 deg.C, 0.5g/100ml conc. sulfuric acid). This polyimide powder is obtd. by reacting an arom. tetracarboxylic acid dianhydride and an arom. diamine in an org. polar solvent to prepare a polyamic acid and then imidating it. In this instance, it is especially important to adjust the logarithmic viscosity of the polyamic acid obtd. before imidation to 0.1-1.2 (at 30 deg.C, 0.5g/100ml dimethyl- acetamide) and it is thereby possible to adjust the logarithmic viscosity of the obtd. polyimide powder to said value.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to polyimide powder, and more particularly to polyimide powder that can be suitably used as a filler.

<Prior Art> Polyimide resins are used as fillers for various molded products and various processed products because of their excellent heat resistance, solvent resistance, mechanical properties, and electrical properties.

When used as a filler, the polyimide resin is processed into powder, and the resulting powder is mixed with other resins to impart the above-mentioned properties of the polyimide resin.

Usually, the above polyimide powder is produced by reacting an aromatic tetracarboxylic dianhydride and an aromatic diamine in an organic polar solvent such as N-methyl-2-pyrrolidone, and then using the resulting high molecular weight polyamic acid in a poor solvent such as water. After pouring into the solution of polyamic acid to precipitate polyamic acid in powder form, it is heated and dried to form polyimide powder, or by heating a solution of polyamic acid to imidize it to precipitate polyimide in powder form. It can be obtained by filtering and drying to obtain polyimide powder.

However, the polyimide powder obtained by such a method not only has an irregular shape but also often aggregates when precipitating the polyimide powder or aggregates during filtering and drying, resulting in polyimide powder having a uniform particle size. difficult to obtain efficiently.

In addition, instead of the method of powdering polyimide during synthesis as described above, there is also a method of pulverizing polyimide films or pellets in a mixer, but the powder obtained in this way has a particle size distribution. Since the powder has a wide range and a non-spherical shape, it may not be possible to mix it uniformly with other resins, resulting in uneven mixing.

<Problems to be Solved by the Invention> Conventional polyimide powders have large variations in particle size and particle size distribution, as in the case of two-part polyimide powder, and even if this is blended with other resins as a filler, it is difficult to mix them uniformly. Therefore, when it is made into a molded product, mechanical strength may be poor due to uneven mixing.
This may result in a very brittle molded body. In addition, when used as a filler to impart the well-known properties of polyimide resin, uniform and stable properties can be achieved due to uneven mixing (
There is a problem that it is not possible to give =1.

Furthermore, if polyimide powder is blended with a resin with poor abrasion resistance, such as polytetrafluoroethylene resin, to make a molded product by utilizing the abrasion resistance of polyimide resin, it may not be sufficiently resistant due to the unevenness of mixing as described above. It was not possible to improve wear resistance.

Therefore, the present invention has small variations in particle size and particle size distribution,
The object of the present invention is to provide a polyimide powder that does not cause uneven mixing even when mixed with other resins, and in particular, a polyimide powder that can impart the excellent characteristics originally possessed by polyimide resins when used as a filler. It is.

Means for Solving the Problems In order to achieve the above object, the present inventors conducted intensive studies and found that the average particle size and particle size distribution were set within a specific range, the molecular weight of the polyimide powder was lowered, and the logarithmic viscosity was reduced. It has been found that by adjusting the amount within a specific range, even when polyimide powder is mixed as a filler, uneven mixing does not occur and an excellent filling effect is exhibited, and the present invention has been completed.

That is, the present invention has an average particle size of 1 to 20 μm and a particle size distribution of 0.
．． 1-50μm, logarithmic viscosity 0.1-0.5 (30"C
10-5g/100ml? The present invention relates to a polyimide powder having a special feature of being (W in sulfuric acid).

In order to obtain the polyimide powder of the present invention, aromatic tetracarboxylic dianhydrides can be used, for example, such as pyromellitic acid, 3.3', 4.4'' biphenyltetracarboxylic acid, 2,3.3',4°-biphenyltetracarboxylic acid, 1,2.4.5-naphthalenetetracarboxylic acid, 1,2,5.6-naphthalenetetracarboxylic acid, 2,3,6.7-naphthalene Tetracarboxylic acid, 3
゜3°, 4,4''-benzophenonetetracarboxylic acid,
dianhydrides of tetracarboxylic acids such as 2,2-bis(4-(2,3-dicarboxyphenoxy)phenyl)propane and 4,4°-bis(2,3-dicarboxyphenoxy)diphenyl ether; Oxide, lower alk.

Examples include kill esters and polyhydric alcohol esters, and these may be used alone or in combination of two or more. Further, in the present invention, the aromatic tetracarboxylic dianhydride (11) is partially 1,2,3°4-butantei.
It can also be used by replacing it with an aliphatic tetracarboxylic dianhydride such as a carboxylic dianhydride.

In addition, the components to be reacted with the aromatic tetracarboxylic dianhydride to obtain the polyimide powder of the present invention include:
Examples include aromatic diamines, specifically 4,4'-diaminodiphenyl ether, 3.3'-dimethyl-
4,4°-diaminodiphenyl ether, 3.3'-dimethoxy-4,4°-diaminodiphenyl ether, 3
．． Diphenyl ether diamines such as 3°-diaminodiphenyl ether and 3.4′-diaminodiphenyl ether, or diphenylthioether diamines such as their thioethers, 4.4′-diaminobenzophenone, and 3.3°-dimethyl-4,4′-diamino Benzophenone diamines such as benzophenone, 3,3°-diaminobenzophenone, 3.3′-diaminodiphenylmethane, 4.4°-diaminodiphenylmethane, 3.
Diphenylmethane diamines such as 3"-dimethyl-4,4"-diaminodiphenylmethane, 2,2'-bis(
4-aminophenyl)propane, 2,2'-bis(3-
Bisphenylpropane diamines such as (aminophenyl)propane, diphenyl sulfoxide diamines such as 4,4°-diaminodiphenylsulfoxide, 3,3''-diaminodiphenylsulfoxide, 4,4'-diaminodiphenylsulfone, 3,3'- Diphenylsulfone diamines such as diaminodiphenylsulfone, benzidine, 3.3'-dimethylbenzidine, 3.3'-dimethoxybenzidine, biphenyl diamines such as 3.3°-diaminobiphenyl, 2,6.-diaminopyridine , 2゜5,-diaminopyridine, pyridine-based diamines such as 3,4.-diaminopyridine, 0-0hata- or p
-diaminobenzene, 3,5-diaminobenzoic acid, etc.
4.4”-di(doaminophenoxy)diphenylsulfone, 4.41-di(p-aminophenoxy)diphenylsulfone, 4.4°-di(doaminophenoxy)diphenyl ether, 4.4°-di(p- aminophenoxy)
diphenyl ether, diphenylpropane, 4,4'-di(p-aminophenoxy)diphenylpropane, 4,4'-di(doaminophenylsulfonyl)diphenyl ether, 4,4°
-di(p-aminophenylsulfonyl) diphenyl ether, 4.4''-di(m-aminophenylthioether) diphenyl sulfide, 4.4'-di(p-aminophenylthioether) diphenyl sulfide, 4.4'
-di(-monoaminophenoxy)diphenylketone, 4,
4°-di(p-aminophenoxy)diphenylketone,
4.4"-di(...-aminophenoxy)diphenylmethane, 4,4"-di(p-aminophenoxy)diphenylmethane, 2.5-diaminotoluene, 2,4-diaminoxylene, diaminodurene, 1.5- Examples include diaminonaphthalene and 2,6-diaminonaphthalene.

These diamines may be used alone or in combination of two or more. Further, the aromatic diamine may be partially substituted with an aliphatic diamine.

Examples of the organic polar solvent used as a reaction solvent for the aromatic tetracarboxylic dianhydride and aromatic diamine include N-methyl-2-pyrrolidone, dimethylacetamide, dimethylformamide, dimethyl sulfoxide, hexamethylenephosphorotriamide, and pyridine. and phenols such as cresol, phenol, and xylenol.

In addition, along with the above solvents, hexane, benzene, toluene,
Organic solvents such as xylene and alcohols may be used in combination.

The polyimide powder of the present invention can be obtained, for example, by reacting the aromatic tetracarboxylic dianhydride with an aromatic diamine, converting the mixture to polyamic acid, which is a precursor of polyimide, and further performing imide conversion.

An example of a specific manufacturing method is as follows.

Aromatic tetracarboxylic dianhydride is added little by little into a solution of aromatic diamine and an organic polar solvent (diamine concentration 1 to 30% by weight, preferably 5 to 10% by weight) to gradually advance the reaction, Synthesize polyamic acid. Next, the temperature is raised to 140 to 250°C for a relatively short time while stirring, for example at a heating rate of about 10°C/min, and the imidization is gradually carried out while removing condensed water accompanying imidization from the reaction system. A reaction is performed to precipitate polyimide particles to form a slurry-like polyimide solution. After cooling the obtained slurry solution,
By filtering, washing and drying, a polyimide powder having the powder characteristics of the present invention is obtained.

The logarithmic viscosity of the polyamic acid obtained before imidization in the above reaction is 0. 1~1,2 (30℃, 0.5g/1
00 ml dimethylacetamide (hereinafter referred to as DMA c), preferably 0.0 ml dimethylacetamide (hereinafter referred to as DMA c). 3-0. By adjusting to the range of 8, the logarithmic viscosity is 0.1 to 0.5 (30℃,
0. 5 g/100 nl of concentrated sulfuric acid) of low molecular weight polyimide is obtained. Further, for the same reason, the solution viscosity measured by a rotational viscometer (B type) is adjusted to a range of 1 to 50 voids (polymer concentration 10% by weight, 25° C.), preferably 5 to 20 voids.

In the present invention, it is important to adjust the viscosity, especially the logarithmic viscosity, and in order to adjust the viscosity, there are two methods: hydrolyzing the polyamic acid by adding a solvent such as water or methanol to the polyamic acid solution, and A method such as heating the polyimide powder at a temperature of 100°C or less can be used, but in order to uniform the particle size and particle size of the target polyimide powder with good reproducibility, it is necessary to strictly control the amount of monomer blended in the reaction. preferable.

In addition, the imidization reaction is carried out smoothly by making the heat distribution of the reaction system uniform, thereby producing the polyimide of the present invention.
In order to obtain the 'j end, the stirring speed during the reaction should be increased from 50 to 40
Orpm, preferably in the range of 100 to 300r+-+m, and the monomer concentration during the reaction is 1.5% to 50% by weight, preferably 10 to 30% by weight. It is better to set it to n.

In addition, in the present invention, in order to accelerate the imidization reaction, shorten the reaction time, and efficiently obtain polyimide particles, pyridine, α-picoline, β-picoline, T-picoline,
1 to 0.1 to 30 tertiary amines such as ethylamine
It can be added within the range of double star%. Furthermore, the molecular weight can be adjusted by adding a molecular chain terminal group-forming compound such as aniline or phthalic anhydride in a range of 0.1 to 30% during the reaction, making it possible to obtain polyimide powder with desirable properties. Can be done.

The polyimide powder of the present invention obtained as described above usually exhibits a spherical shape, has an average particle size of 1 to 20 μm, preferably 5 to 10 μm, and a particle size distribution of 0.1 to 50 μm, preferably 1 to 3 Q It is p m. If the average particle size is too small, there is a tendency for secondary agglomeration during the washing and drying process to form irregularly shaped particles, and if it is too large, it may be difficult to mix uniformly with other resins. If the particle size distribution is less than 0.1 μm,
When mixed with other resins, the properties of polyimide powder cannot be fully exhibited, and if it exceeds 50 tJ m, uneven mixing may occur or a brittle molded product may result.

Furthermore, the polyimide powder of the present invention has a bulk specific gravity of 0.
It is preferable to adjust it within the range of 1 to 1,0/cc; outside this range, when mixed with other resins, the appearance of the molded product will be poor, and the molded product will be brittle, resulting in unsatisfactory properties. may not be obtained.

The polyimide powder of the present invention having the above characteristics can be blended with other resins as a filler to improve the mechanical properties (such as abrasion resistance) and heat resistance of the polyimide resin. By blending it with polytetrafluoroethylene resin, which has poor abrasion resistance,
A molded article with excellent properties that combines the properties of both resins can be obtained.

Therefore, the powder of the present invention has 1Vlit thermal properties, mechanical properties,
Suitable as a filler for molded bodies used in applications that require properties such as chemical resistance and abrasion resistance, such as heat-sensitive sliding parts used in copiers, facsimile machines, printers, etc., and sliding bearing parts in compressors, etc. It can be used for

<Effects of the Invention> As described above, the polyimide powder of the present invention is a powder with a uniform average particle size and particle size distribution, and has a logarithmic viscosity of 0.1 to 0.
．． Since it has a low molecular weight adjusted to a range of 5, it has excellent dispersibility, conformability, and cohesiveness when mixed with other resins as a filler. Therefore, when it is mixed into a molded article as a filler, it does not cause poor mechanical strength (brittleness) due to uneven mixing or non-uniform dispersion.

<Examples> Examples of the present invention will be shown below and explained in more detail.

Example 1 200.4'-diaminodiphenyl ether (hereinafter referred to as DDE) was placed in a 51 quart flask. and 4598 g of N-methyl-2-pyrrolidone (hereinafter referred to as NMP) were mixed and completely dissolved with stirring at room temperature. Next, pyromellitic dianhydride (hereinafter referred to as PMDA) was added to this solution.
>196g of DM was added in small portions to react, and the logarithmic viscosity was 0.52 (30℃, 0.5g/100mlDM).
A c),) 8 Liquid viscosity 10 Boise (B type viscometer, 25
℃) was obtained.

Next, this polyamic acid solution was heated while stirring, and
A dehydration ring-closing reaction of the polyamic acid occurred in a temperature range of 0 to 175°C, and the resulting distillation of water caused the solution to rapidly become cloudy, and polyimide powder precipitated in the form of a slurry.

Further, the solution was heated to 190°C and the reaction was continued for 2 hours.

After the reaction is complete, cool the reaction solution and filter the polyimide powder.
1i away.

The obtained powder was washed with NMP and acetone, and then the polyimide powder was heated and dried at 250°C for 3 hours to obtain 320 g (yield: 92%) of the polyimide powder of the present invention.

Example 2 DDE 180 g, PMDA 218 g, NMP45
332 g (yield: 90%) of the polyimide powder of the present invention was obtained in the same manner as in Example 1 except that 98 g was used.

Example 3 Example 1 except that 200 g of DDE, 96 g of PMDAI, 30 g of phthalic anhydride, and 459 gg of NMP were used.
In the same manner as above, 370 g (yield 95%) of polyimide powder of the present invention was obtained.

Example 4 414 g of polyimide powder of the present invention was prepared in the same manner as in Example 1 except that 200 g of DDE, 265 g of s-biphenyltetracarboxylic dianhydride, and 4185 g of NMP were used.
A yield of 95% was obtained.

Comparative Example 1 NMP was added to the polyamic acid solution obtained in Example 1 so that the polyamic acid concentration was 5% by weight.

This solution was added dropwise to 5 times the amount of water in a high-speed stirring mixer to precipitate polyamic acid powder.

Next, the obtained powder was filtered and washed with water.
The mixture was dried at 00°C for 3 hours and further dried at 250°C for 12 hours to obtain 203g (yield: 75%) of irregularly shaped polyimide powder.

Comparative example 2 DDE200 g, PMDA218 g, NMP418
344 g (yield: 98%) of polyimide powder was obtained in the same manner as in Example 1, except that 5 g was used.

Comparative Example 3 A polyimide molded body obtained from PMDA and DDE was cut using a lathe, and the resulting cut product was pulverized using a pulverizer to obtain irregularly shaped polyimide powder.

20% by weight of the polyimide powder obtained in each of the above Examples and Comparative Examples was added to polytetrafluoroethylene resin (hereinafter referred to as PTFE), and a compression cuff of 00 kg was prepared.
/c self-molding and sintering at 370°C to create a polyimide powder-filled PTFE molded body.

The properties of the polyimide powder obtained in each example and comparative example and the properties when made into a PTFE molded body were measured,
The results are shown in Tables 1 and 2.

Note that the measurement method for each characteristic is as follows.

[Average particle size and particle size distribution]

Measurement was performed using Coulter Counter TAII (manufactured by Nikkaki Co., Ltd.).

[Logarithmic viscosity η]

0.5 at 30°C using an Ubbelohde viscometer
The viscosity of polyamic acid or polyimide at a concentration of g/100ml was measured and calculated using the following viscosity formula.

The solvent used was DMAc in the case of polyamic acid, and concentrated sulfuric acid was used in the case of polyimide.

ηtnh = Polymer concentration (C, g/dj [Tensile strength and elongation] Measurement was performed using Autograph AGB model (manufactured by Kinsei Co., Ltd.).

(Amount of wear) A sleeve-shaped ring (aluminum) measuring φ20×φ25.6×lot was fixed, and a sleeve-shaped sample measuring φ20×φ25.6×lot was rotated and slid on the ring for measurement.

Note that dry sliding friction was performed at room temperature at a speed of 1 m/sec and a load of 5 kg/crA.

(Hereafter, margin) Table 1 Table 2

Claims (1)

[Claims] (1) Average particle size is 1 to 20 μm, particle size distribution is 0.1 to 5
0μm, logarithmic viscosity 0.1-0.5 (30℃, 0.5g
/100ml of concentrated sulfuric acid).