JP2564028B2 - Polyimide resin powder and molded body - Google Patents

Description

TECHNICAL FIELD The present invention relates to a polyimide resin powder having excellent moldability and a molded product obtained therefrom. More specifically, the present invention relates to a polyimide resin powder capable of producing a polyimide molded body having excellent mechanical properties and a polyimide resin molded body having high strength and high toughness obtained by compression molding.

[Prior Art] Aromatic polyimide resin moldings have various properties such as abrasion resistance, chemical resistance, and radiation resistance in addition to excellent heat resistance, and are used as mechanical parts such as sliding members. It is also widely used in the fields of automobiles, office equipment, electric / electronic equipment, aviation / space, nuclear power, and general industrial machinery.

However, in order to further expand the applications of polyimide resins having such excellent properties as, for example, metal substitute materials and precision structural materials, it is essential to improve mechanical properties such as strength and toughness. Continuous efforts are being made.

Since such a polyimide resin is generally insoluble in an organic solvent and does not heat-melt, a method for producing a thick molded product is to compress and mold polyimide resin powder, and simultaneously and / or at the time of compression molding. A method is used in which after compression molding, heat treatment is performed in a pressureless state.

As a method for producing an aromatic polyimide resin powder, for example, the method disclosed in Japanese Patent Publication No. 39-30060,
That is, an aromatic tetracarboxylic dianhydride and an aromatic diamine are reacted in an organic polar solvent to obtain a solution of a polyamic acid, which is then thermally dehydrated and ring-closed, and then dried in a vacuum drier, and then There is a method of obtaining a polyimide resin powder by heating at 325 ° C. for 16 hours. In addition, as disclosed in JP-B-39-9088 and JP-A-61-252228, an aromatic tetracarboxylic acid dianhydride and an aromatic diamine are reacted in an organic polar solvent to form a polyamic acid. A solution is prepared, and then this solution is brought into contact with a poor solvent for polyamic acid such as water, toluene, hexane, etc. to prepare polyamic acid as a powder, and this is heated to obtain a polyimide resin powder. −
As disclosed in Japanese Patent No. 26926, there can be found a method in which an aromatic tetracarboxylic acid component and an aromatic diisocyanate are reacted in an organic polar solvent to directly obtain a polyimide resin powder.

[Problems to be Solved by the Invention] According to these conventional methods, a large specific surface area and about
A polyimide resin powder having a high imidization rate of 100% and high crystallinity or a polyimide resin powder having a small specific surface area, low imidization rate and low crystallinity can be obtained.

However, the specific surface area of the polyimide resin powder is closely related to the specific gravity and mechanical properties of the compression molded product, and if the specific surface area is small, the cohesiveness between the powders in the compression molded product will be insufficient and The proportion of voids in the body increases, and the specific gravity and mechanical properties of the molded body deteriorate. Further, if the imidization ratio and crystallinity of the polyimide resin powder are too high, the interaction between the powders during compression molding and heat treatment of the molded product becomes insufficient, and the mechanical properties of the molded product deteriorate.

That is, in order to improve the mechanical properties of the polyimide resin molded body, it is an object to develop a polyimide resin powder having a specific surface area larger than a certain level and an appropriate imidization ratio and crystallinity.

[Means for Solving the Problems] As a result of intensive studies in view of the above problems, the present inventors have made a polyimide resin powder for producing a polyimide resin molded product having excellent heat resistance and mechanical properties, and the resin powder. Thus, a polyimide resin molded body having high strength and high toughness obtained by compression molding has been provided. Specifically, 20
It enables the production of a polyimide resin powder having a specific surface area of m ² / g or more and an imidization ratio lower than 90%, and further, by using such a polyimide resin powder, the specific gravity, strength and toughness are significantly increased. It has been found that an improved polyimide molding can be obtained, and the present invention has been completed.

The present invention has the general formula (I): (In the formula, R ₀ represents a tetravalent aromatic group having 6 to 30 carbon atoms, R ₁ represents a divalent aromatic group having 6 to 30 carbon atoms, and n represents a positive integer.) The present invention relates to a polyimide resin powder containing an aromatic polyimide resin powder having a specific surface area of 20 m ² / g or more and an imidization ratio of less than 90%.

Furthermore, the present invention relates to a polyimide resin molded article, characterized in that the polyimide resin powder is compression molded, and is subjected to a heat treatment in the state of no pressure after the compression molding and / or the compression molding. .

[Example] The polyimide resin powder of the present invention has a specific surface area of at least 1 m ² / g or more, preferably 10 m ² / g or more, particularly preferably 20 m ² / g or more, and an imidization ratio of less than 95%. , Preferably has a characteristic value of less than 90%, and its logarithmic viscosity is generally 0.1 when measured at a concentration of 0.5 g / 100 ml as a solution of concentrated sulfuric acid at 30 ° C.
It has a value of ˜2.0, but is preferably at least 0.1 or more. Even if a polyimide resin powder having a value of less than 0.1 is used, the polyimide resin molded product obtained from this will not exhibit sufficient mechanical strength. Therefore, the polyimide resin molding obtained by compression molding the powder of the present invention has excellent heat resistance, high specific gravity, high strength and high toughness. The imidization ratio here is the ratio of the amide acid ring-closed to the imide, and is calculated, for example, by measuring the Fourier transform infrared absorption spectrum. Specifically, first, the ratio of the absorbance of the absorption around 880 cm ^-1 in the first based on the absorption and the benzene ring in the vicinity of 720 cm ^-1 based on the imide ring (hereinafter, this ratio and r) obtained. Next, the imidization ratio of polyamic acid was set to 0%, and
No. 060, that is, by reacting an aromatic tetracarboxylic dianhydride and an aromatic diamine in an organic polar solvent to obtain a polyamic acid solution, which is then thermally dehydrated and ring-closed. The polyimide resin powder produced by the method is further heat-treated at 300 ° C. for 5 hours, and the imidation ratio of the powder obtained is taken as 100%, and is given as a relative value proportional to the magnitude of r.

In the polyimide containing the repeating unit represented by the general formula (I) of the present invention, R ₀ is preferably a tetravalent aromatic group having 6 to 30 carbon atoms. Specific examples of such groups include pyromellitic acid, 3,3 ', 4,4'-biphenyltetracarboxylic acid, 3,3', 4,4'-benzophenonetetracarboxylic acid, 3,3 ', 4, From 4'-diphenylsulfone tetracarboxylic acid, 3,3 ', 4,4'-diphenyl ether tetracarboxylic acid, naphthalene-1,2,5,6-tetracarboxylic acid, 2,2-hexafluoropropylidene-bisphthalic acid Examples thereof include residues excluding the carboxylic acid group, and these can be used alone or as a mixture of two or more kinds. Of these, a pyromellitic acid residue is particularly preferable.

Further, R ₁ is preferably a divalent organic group containing an aromatic group having 6 to 30 carbon atoms and a group in which a carbon atom forming an aromatic ring serves as a bond. Specific examples of such groups include 4,4′-diaminodiphenyl ether, 3,4 ′
-Diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfide, 4,4'-bis (4-aminophenoxy) biphenyl, 4,4'-diaminodiphenyl sulfone, 3,3'-diamino Diphenyl sulfone, 3,3'-diaminobenzophenone, 2,5-diaminobenzamide, 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 (3-aminophenoxy) benzene, 1,3-bis (4
-Aminophenoxy) benzene, 1,4-bis (4-aminophenyl) benzene, bis {4- (4-aminophenoxy) phenyl} ether, 4,4'-diaminodiphenylmethane, bis (3-ethyl-4-amino) Phenyl) methane, bis (3-methyl-4-aminophenyl) methane, bis (3-chloro-4-aminophenyl) methane,
4,4'-diaminobiphenyl, 4,4'-diaminooctafluorobiphenyl, 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, 2,4-diaminotoluene, 1,3-diaminobenzene,
1,4-diaminobenzene, 2,2'-bis {4- (4-aminophenoxy) phenyl} propane, 2,2'-bis {4
-(4-aminophenoxy) phenyl} hexafluoropropane, 2,2'-bis (4-aminophenyl) propane, 2,2'-bis (4-aminophenyl) hexafluoropropane, 2,2'-bis ( 3-hydroxy-4-aminophenyl) propane, 2,2'-bis (3-hydroxy-4-aminophenyl) hexafluoropropane, 9,
Examples thereof include 9'-bis (4-aminophenyl) -10-hydroanthracene and a residue obtained by removing an amino group from orthotolidine sulfone, and these can be used alone or as a mixture of two or more kinds. Among these, 4,
A residue obtained by removing an amino group from 4'-diaminodiphenyl ether is preferable.

The polyimide resin powder of the present invention includes, for example, aromatic tetracarboxylic acid dianhydride such as pyromellitic dianhydride and aromatic diamine such as 4,4′-diaminodiphenyl ether, for example, pyridine and N, N. -Dimethylacetamide or N, N-dimethylformamide is reacted in an organic polar solvent to prepare a polyamic acid solution, and then the polyamic acid solution is heated to dehydrate and ring-close the polyamic acid, then cooled and filtered. The obtained powder can be produced by a method such as drying at a temperature of about 200 ° C. or lower.

That is, the polyimide resin powder according to the present invention has both a large specific surface area and a low imidization ratio necessary for producing a molded product having excellent mechanical properties, and moreover, for example, a polyamic acid solution is thermally treated. It is characterized in that it can be produced by an extremely simple method in which dehydration ring closure is carried out and imidization is carried out.

As a method for producing the polyimide resin molded product of the present invention from the novel polyimide resin powder of the present invention, the following methods are known techniques.

For example, hundreds to thousands of resin powders filled in the mold
A temperature of not less than the glass transition temperature and not more than the decomposition temperature of the polyimide resin is obtained by carrying out compression molding at a pressure of kg / cm ² and at the same time as this compression molding in a pressurized state and / or after performing compression molding without pressure. Hundred to several hundreds with a CIP device (cold hydrostatic pressure device) and / or a HIP device (hot hydrostatic pressure device) after the resin powder is filled into a rubber case or the like having elasticity by a heat treatment method. There is a method of treating at a pressure of 1,000 kg / cm ² and at the same time performing heat treatment at a temperature not lower than the glass transition temperature and not higher than the decomposition temperature of the polyimide resin under pressure and / or no pressure after treatment. The polyimide resin molding of the present invention can be manufactured by any of these methods.

Further, the present invention will be specifically described by the following examples, but the present invention is not limited to these examples.

Example 1 Under a nitrogen stream, 20.02 g (0.10 mol) of 4,4′-diaminodiphenyl ether (hereinafter, referred to as ODA) is 250 ml of N, N-dimethylacetamide (hereinafter, referred to as DMAc) and pyridine (hereinafter, referred to as Py). ) After dissolving in 250 ml of mixed solution,
Under ice cooling, pyromellitic dianhydride (hereinafter referred to as PMDA)
21.81 g (0.10 mol) was gradually added as a powder in about 30 minutes. After the addition was completed, stirring was continued for 60 minutes to obtain about 500 ml of a polyamic acid solution.

Subsequently, the obtained polyamic acid solution was heated, and heating and stirring were continued. The internal temperature at this time was 110 ° C. After cooling, the powder obtained by filtration was washed with DMAc and methanol in this order, and filtration was repeated.

Further, the powder was dried under reduced pressure at 150 ° C. for several hours, and then heat-treated at 200 ° C. in a perfect oven to obtain an absolutely dry state, to obtain about 36 g of the polyimide resin powder of the present invention.

A part of the polyimide resin powder obtained by the above treatment is taken, and its specific surface area and imidization ratio are respectively calculated by BET
It was calculated by measuring the specific surface area using the method and measuring the infrared absorption spectrum. The diffraction intensity was measured using a wide-angle X-ray diffractometer to evaluate the crystallinity of this polyimide resin powder. As shown in the diffraction intensity curve in FIG.
, 11 ° (peak 1), 14 ° (peak 2), 23 ° (peak 3) and 27 ° (peak 4). This indicates that the polyimide resin powder is crystalline in nature.

After that, the remaining polyimide resin powder was filled in a mold and pressed at room temperature at 5000 kg / cm ² pressure for 3 minutes using a hydraulic compression molding machine. Furthermore, under no pressure, under a nitrogen stream,
Heat treatment was performed at 450 ° C for 30 minutes to obtain a polyimide resin molded body.

About the polyimide resin molded body thus obtained, specific gravity (JIS K 7112 method), bending strength and bending elastic modulus (JIS K 7203 method), tensile breaking strength and tensile breaking elongation (JIS K 6911 method) , V-notched Izod impact strength (JIS K 7110 method) was measured. Combine these results with the results of specific surface area and imidization ratio
Shown in the table.

Example 2 The polyimide resin powder of the present invention was reacted and treated in the same manner as in Example 1 except that 250 ml of N, N-dimethylformamide (hereinafter referred to as DMF) was used instead of the DMAc used in Example 1. I got about 36g.

A part of the obtained polyimide resin powder was taken, and its specific surface area and imidization ratio were calculated in the same manner as in Example 1.

After that, the remaining polyimide resin powder was treated in the same manner as in Example 1 to obtain a polyimide resin molded body.

The polyimide resin moldings thus obtained were measured for specific gravity, flexural strength and elastic modulus, tensile breaking strength and tensile breaking elongation, and Izod impact strength with V-notch in the same manner as in Example 1. These results are shown in Table 1 together with the results of specific surface area and imidization ratio.

Comparative Example 1 The polyamic acid solution obtained in the same manner as in Example 1 was heated, and heating and stirring were continued. The internal temperature at this time was 132 ° C. After cooling, the powder obtained by filtration was washed with DMAc and methanol in this order, and filtration was repeated.

Further, the powder was dried under reduced pressure at 150 ° C. for several hours and then treated at 200 ° C. in a perfect oven to obtain about 37 g of polyimide resin powder.

A part of the obtained polyimide resin powder was taken, and its specific surface area and imidization ratio were calculated in the same manner as in Example 1.

After that, the remaining polyimide resin powder was treated in the same manner as in Example 1 to obtain a polyimide resin molded body.

The specific gravity, flexural strength and flexural modulus, tensile breaking strength and tensile breaking elongation, and V-notched Izod impact strength of the thus obtained polyimide resin molded article were measured in the same manner as in Example 1. Combine these results with the results of specific surface area and imidization ratio
Shown in the table.

Comparative Example 2 100 m of polyamic acid solution obtained in the same manner as in Example 1
After taking l, DMAc (40 ml) was added to this and thoroughly stirred, and then 1200 ml of methylene chloride was gradually added with vigorous stirring to obtain a polyamic acid powder in the form of a slurry. The obtained polyamic acid powder was washed with methylene chloride and filtered repeatedly.

Further, the powder was dried under reduced pressure at 150 ° C. for several hours and then treated at 200 ° C. in a perfect oven to obtain about 7.2 g of polyimide resin powder.

A part of the obtained polyimide resin powder was taken, and its specific surface area and imidization ratio were calculated in the same manner as in Example 1.

After that, the remaining polyimide resin powder was treated in the same manner as in Example 1 to obtain a polyimide resin molded body.

The specific gravity, flexural strength and flexural modulus, tensile rupture strength and tensile rupture elongation, and V-notched Izod impact strength of the thus obtained polyimide resin molded article were measured in the same manner as in Example 1. Combine these results with the results of specific surface area and imidization ratio
Shown in the table.

From Table 1, the polyimide resin powders obtained from Examples 1 and 2 have both a specific surface area of more than 20 m ² / g and an imidization ratio of less than 90%, and from FIG. It can be seen that it is crystalline.
A polyimide resin molded body obtained by compression molding such a polyimide resin powder exhibits high specific gravity, high tensile breaking strength and tensile breaking elongation, and high impact strength.

EFFECTS OF THE INVENTION The present invention provides an essentially crystalline polyimide resin powder having a larger specific surface area and a lower imidization ratio. In addition, the polyimide resin molded product obtained by compression molding it is extremely excellent in mechanical properties such as strength and toughness in addition to the high heat resistance which is the original property of aromatic polyimide resin, and it is suitable for mechanical parts. It can be used very extensively and usefully.

[Brief description of drawings]

FIG. 1 is a wide-angle X-ray diffraction intensity curve of the polyimide resin powder of the present invention obtained according to Example 1.

Claims (2)

(57) [Claims] 1. General formula (I): (In the formula, R ₀ represents a tetravalent aromatic group having 6 to 30 carbon atoms, R ₁ represents a divalent aromatic group having 6 to 30 carbon atoms, and n represents a positive integer.) An aromatic polyimide resin powder containing the polyimide resin powder, which has a specific surface area of 20 m ² / g or more and an imidization ratio of less than 90%. 2. A polyimide resin molded article, characterized in that the polyimide resin powder according to claim 1 is compression molded, and is subjected to heat treatment at the same time as compression molding and / or compression molding, and then under no pressure. .