JPS6097834A - Monoaxially orientated total aromatic copolyimide molded material - Google Patents

Abstract

PURPOSE:To get monoaxial orientated total aromatic copoly-imide molded material of high strength, high coefficient elasticity and excellent heat resistance by a method wherein integrity aromatic diamine is reacted with specific mixture of aromatic tetracarboxylic acid dianhydrous compound. CONSTITUTION:Mixtures of integrity aromatic diamine (for instance, p-phenylene diamine, 2,7-diaminofluorene, 2,6-diamino naphtalene) and pyromellitic anhydride with molar ratio 90/10-20/80 and 3,3',4,4'-diphenyl ether tetra carboxylic acid dianhydrous compound are isomolar reacted and are made into polyamid acid, and the desired monoaxial orientated molded material is made by cyclizing to imido group. When it is made into fibers the strength is above 10g/d and the coefficient of elasticity is above 900g/d. It is useful for resin reinforcing fiber or laminated material.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a -axis-oriented wholly aromatic copolyimide molded product which has high strength, high modulus of elasticity, and extremely high heat resistance.

Fully aromatic polyimide has the highest heat resistance among organic polymers, and has already been put to practical use in films and molded products by taking advantage of this characteristic. However, their tensile properties are very common, and their strength and modulus are not high. As an example of obtaining a polyimide molded product with a high elastic modulus, in Japanese Patent Publication No. 57-37687, a solution of polyamic acid consisting of a rigid aromatic diamine and a specific aromatic tetracarboxylic dianhydride was wet-spun and stretched. A method is disclosed in which the compound is then cyclized into an imide group by heating. The present inventors have developed a method that has high strength, high modulus of elasticity, and extremely good heat resistance.
As a result of intensive research aimed at producing uniaxially oriented molded products such as fibers, films, and tapes, we developed a fully aromatic compound consisting of a rigid aromatic diamine or a mixture thereof and a mixture of two specific aromatic tetracarboxylic dianhydrides. We have discovered that polyimide is suitable for this purpose and have arrived at the present invention.

The molded product of the present invention comprises an aromatic diamine or a mixture thereof in which the chain extension bonds are coaxial, nearly coaxial, or parallel and extend in opposite directions, and anhydrous Biomellito II (A> and 3.3',
4. Consisting of 4'-diphenyl ether tetracarboxylic dianhydride (B), Al6 (molar ratio) is 90/10 to 2
It is a fully aromatic copolyimide molded product with a -axis orientation of 0/80.

Taking the case of fiber as an example, the copolyimide molded product of the present invention has a strength of 10 q/d or more and an elastic modulus of 900 G/d or more, and also has extremely high heat resistance and chemical resistance, and has many Useful for applications such as

The present invention will be explained in more detail below. Once the wholly aromatic copolyimide of the present invention is made, it no longer melts and there are no solvents. Therefore, it is necessary to first prepare a polyamic acid precursor which is soluble in an organic solvent, then to shape it, and then to cyclize it into an imide group using an appropriate means.

Therefore, first, the method for producing polyamic acid will be explained. The aromatic diamine used in the present invention has a so-called rigid structure in which the chain extending bonds are coaxial, almost coaxial, or parallel and extend in opposite directions, such as benzidine, 2,2'-dichlorobenzidine, and 4.4''-diamino- Examples include p-terphenyl.

Examples of the coaxial type are 2,7-diamitsufluorene,
Examples thereof include 2,7-diamitfluorenone and 2,7-diamitudibenzofuran. Also, as a parallel type, 2.6
-diaminonaphthalene, 1,5-diaminonaphthalene, etc. These diamines may be used alone or as a mixture of two or more for polymerization. On the other hand, as the acid anhydride, pyromellitic anhydride (A) and 3.3',4.4'-diphenyl ether tetracarboxylic dianhydride (B) are used. A/8 (molar ratio) is 90/10 to 20/80, and outside this range, a high-performance molded product cannot be obtained as shown in the comparative example.

By dissolving the above diamine or diamine mixture in an amide solvent, and then adding and polycondensing the mixture of the above acid anhydrides in substantially equimolar amounts to the diamine component, a solution of polyamic acid, which is a precursor polymer, is obtained. It will be done. As the amide solvent used for polymerization, N-methylpyrrolidone (NM
P), N1N-dimethylacetamide, N,N-dimethylformamide, and the like.

Using the polyamic acid solution thus obtained, fibers,
Molded into films, tapes, etc. The methods can be broadly divided into wet methods and dry methods, but the wet method will be explained first.

The stock solution used in the wet method may be the above-mentioned polyamic acid solution itself, but the present inventors have previously proposed
It is more preferable to use a partially cyclized polymer solution, in which a part of the amic acid units are cyclized in solution using a chemical cyclizing agent, as proposed in 2007, as it provides a transparent, void-free wet molded product. As such a cyclizing agent, aliphatic acid anhydrides such as acetic anhydride and propionic anhydride are suitable. The amount added is about 0.1 equivalent to 0.4 equivalent relative to the amic acid unit.

This chemical cyclization includes pyridine, 3-methylpyridine, 3.
Organic bases such as 5-lutidine and quinoline may be used as catalysts. The amount added is not particularly limited.

The above polyamic acid solution or a polymer solution in which a portion of the amic acid is cyclized into imide groups is extruded into an aqueous coagulation bath through an orifice, a slit die, or the like. Alternatively, it is cast onto a flat plate and immersed in an aqueous coagulation bath. The coagulation bath may be water, an aqueous solution of a polymerization solvent, or an aqueous solution of an inorganic salt, but from the viewpoint of ease of recovery of the polymerization solvent, an aqueous solution of the same solvent is most preferable, and the coagulation bath temperature is 0 to 50°C. is appropriate. The solidified molding may subsequently be stretched.

This stretching may be carried out in water, which also serves as washing, or may be carried out in air. Stretching temperature is 10-90
℃ is suitable, and the stretching ratio is 1.2 to 3.0 times.

The unstretched or stretched solidified molded product is dried as it is,
Then, it is subjected to thermal cyclization or treated with a chemical cyclizing agent while swollen to close the amic acid to an imide group. The cyclizing agent and catalyst used in the latter case are the same as those used for the partial cyclization in solution, and the combination of acetic anhydride and pyridine is particularly suitable. Note that, before chemically cyclizing the solidified molded product, water in the molded product may be extracted and removed by washing with an organic solvent that does not contain active hydrogen and is miscible with water.

Suitable solvents include acetone, tetrahydrofuran, dioxane, and the like. Further, other organic solvents may be used as diluents during chemical cyclization. Such diluents include dioxane, benzene, toluene, chloroform, carbon tetrachloride, acetonitrile, and the like. Chemical cyclization treatment conditions are temperature 15-50
℃, and the treatment time ranges from 10 minutes to 1 day or more. The chemically cyclized molded product is then dried, but before drying, it may be washed with an organic solvent to remove the cyclizing agent. As such a cleaning agent, either air drying, continuous drying using a heated drum, or drying may be employed.

・:1 (The dried molded product is finally subjected to hot stretching or heat treatment.For molded products that have not been chemically cyclized, the amic acid is thermally cyclized to imide groups in step 1. Molding of polyamic acid. If the product is not stretched at the product stage, it must be stretched in this step. Either a hot plate or a heating tube may be used as a means for stretching. Also, hot stretching or heat treatment involves increasing the temperature in stages. The final temperature is preferably 400° C. or higher, and the atmosphere is air or an inert gas such as nitrogen.

Next, dry molding will be explained. In this case as well, there is a method of using the polyamic acid solution obtained by polymerization as the stock solution as it is,
There is a method of using a polymer solution to which a chemical cyclizing agent is added under temperature conditions (10° C. or lower) where cyclization does not substantially occur. In the latter case, after being molded into a shape such as a film, the temperature is raised to a temperature at which cyclization occurs to cause gelation and form retention. The chemical cyclizing agent used is the same as that described in the wet molding section, and the amount added can be extruded by 1.5 to 3° relative to the amic acid equivalent to form a film.

Then, the temperature is raised to evaporate the solvent and proceed with thermal cyclization. In the case of a solution containing a chemical cyclizing agent, fibers can also be produced by discharging a polyamic acid solution into a hot air stream through a die. The thus obtained molded articles, such as fibers and films, must then be stretched. Stretching may be carried out with a portion of the solvent remaining, or may be carried out after the solvent has been completely evaporated. Generally, the former method is easier to operate because it can be stretched at a lower temperature. The hot stretching and heat treatment methods are exactly the same as those for the wet molded product described above.

The uniaxially oriented wholly aromatic copolyimide molded product of the present invention is
Taking fiber as an example, m1flOq/d or more, elastic modulus 900
It has extremely high performance with C1/d or higher, and has excellent heat resistance and chemical resistance. Therefore, it is useful for many uses, such as reinforcing rubber, resin, etc., and heat-resistant insulation. In addition, the laminated tape was diluted with MP and measured at 25° C. when used as a structural material.

9-li, sample length 100mm, tensile speed 20mm/1lli
n 0 Also, the film has a trial length of 25 mm and a tensile speed of 10
It was measured in terms of work/min.

・II Example 1 In this example, the diamine component was benzidine, and the acid anhydride component was pyromellitic anhydride (PMDA), 40 mol%, 3.3'4
．． The results of spinning a copolyimide fiber containing 60 mol% of 4'-diphenyl ether tetracarboxylic dianhydride (DEDA) are shown.

PMDA3.12 was prepared by dissolving benzidine 6.55Q in dehydrated NMProom, grinding it well in a mortar, and mixing it.
G and DEDA6.650 were added and polymerized, η1n
A solution of polyamic acid with h2.38 was obtained (polymer concentration 1
4.0%).

This polyamic acid solution was cooled with ice water, and while stirring, a mixture consisting of 1.46Q acetic anhydride, 1.13Q pyridine (1 (both 0.2 equivalents of amic acid unit) and NMP17+al was added dropwise over 30 minutes, The reaction was continued at 25°C for 5 hours at 10°C.The resulting partially cyclized polyamic acid solution had a polymer concentration of 12.0%, and then at 25°C.
The film was stretched 1.4 times in water. The coagulated thread was immersed in acetic anhydride/pyridine (volume ratio 70/30) overnight at room temperature to chemically dissolve the remaining amic acid. This chemically cyclized yarn was immersed in toluene for 90 minutes, then re-wound and vacuum-dried. Then, using a glass cylindrical tube with a length of 30 cm+ through which nitrogen was gently passed, the material was hot-stretched to 6.5 times at 550° C. (fiber feeding speed 113, On+/min). The yarn quality of this hot drawn yarn is a fineness of 7.3 denier, a strength of 19.5 q/d,
It had high performance with an elongation of 1.7% and an elastic modulus of 1274 a/d.

This drawn yarn was further heated at 525°C for 6 seconds under a nitrogen atmosphere.
After tension heat treatment, strength: 19.70/d1 elongation: 1.7
%, and the elastic modulus was 1310 q/d, indicating a slight improvement in performance.

Comparative Example 1 This comparative example shows the results of spinning homopolyimide fibers made of benzidine and PMDA.

By reacting benzine and PMDA in NMP, boria 11
degree 6.0%, η1nh5.74, solution viscosity 8550p
A polyamic acid solution of oise was obtained. A portion of this solution was prepared using almost the same recipe as in Example 1, and 0.1 of the amic acid unit was added.
5 equivalents of acetic anhydride and pyridine, plus an appropriate amount of NM
Add P, polymer concentration 4°0%, solution viscosity 93 Q p
A partially cyclized polyamic acid solution of oise was prepared.

゛This solution was wet-spun using the same equipment and recipe as in Example 1, stretched to 1.4 times in water, and then immersed in acetic anhydride/pyridine (70/30) overnight at room temperature for chemical cyclization. . Next, I tried vacuum drying and hot stretching in a nitrogen atmosphere, but the stretching was only 1.03 times even at 600°C, and the yarn quality was 14.0 denier, strength 7.70/d, and elongation 1. ．．
0% and an elastic modulus of 877 o/d, which was considerably inferior to the fiber of Example 1.

Comparative Example 2 This comparative example shows the results of spinning homopolyimide fibers made of benzidine and DEDA.

By reacting benzidine and DEDA in NMP, polyv1
A polyamic acid solution with a concentration of 15.1% and η1nh of 1.70 was prepared, and then acetic anhydride and pyridine in an amount of 0.17 equivalents of the amic acid unit, and an appropriate amount of NMP were added to give a polymer concentration of 14.1% and a solution viscosity. A partially cyclized polymer solution of 460 poise was obtained.

This solution was wet-spun using the same formulation as in Example 1, and after being stretched 1.44 times in water at room temperature, the anhydrous vinegar yarn at room temperature had a fineness of 18.4 denier and a strength of 10.7□6/d. Example 2 This example shows the spinning results of several copolyimides within the scope of the present invention, 5illI, consisting of benzidine, PMDA and DED13-A. The recipes for polymerization, partial cyclization in solution, wet spinning, chemical cyclization of coagulated yarn, and hot stretching are almost the same as in Example 1. The results are summarized in Table 1. All fiAHs have higher strength and modulus than the fibers of Comparative Example 1.2.

14- Table 1 Example 3 2-Chlorbenzidine, PMDA (70 mol%), and DEDA (30 mol%) were polymerized in NMP to obtain a polyamic acid solution with a polymer concentration of 17.0% and η1nh1.71 (7). Ta. Next, acetic anhydride and pyridine (both 0.2 equivalents of the amic acid unit) were added to the same recipe as in Example 1, and a small amount of NMP was added to prepare a partially cyclized polymer solution of Oise (polymer concentration: 15.7%, solution viscosity: 29801). I made it.

This solution was wet-spun using the same equipment and method as in Example 1, and was immersed in acetic anhydride/pyridine (70/30) overnight at room temperature for chemical cyclization. After vacuum drying, the yarn quality of 1111 obtained by hot stretching 4.2 times at 550° C. in a nitrogen atmosphere has a fineness of 17.0 denier, a strength of 17.00/d, an elongation of 1.9%, and an elastic modulus. It was 1066 o/d.

Example 4 In this example, the diamine component was 30 mol% of benzidine, 2.
The results of spinning a copolyimide fiber consisting of 70 mol% of 2'-dichlorobenzidine and whose acid anhydride components are 1) 70 mol% of MDA and 30 mol% of DEDA are shown.

In addition, polymer concentration 15.6%, solution viscosity 1i 1320pO
+se partially cyclized polymer solution was obtained.

The dried yarn obtained by chemical cyclization was heated at 575°C for 5 minutes in a nitrogen atmosphere.
．． It was hot stretched twice. The drawn yarn has a fineness of 12.9 denier and a strength of 18. Oq/d, elongation 2°1%, elastic modulus 9.
It was 860/d.

Example 5 This example shows the results of spinning a copolyimide m-fiber in which the diamine component is 4.4''-diamino-p-terphenyl and the acid anhydride component is 35 mol% PM17-DA and 65 mol% DEDA.

The above monomers were reacted in NMP, and the polymer concentration was 17%.
A polyamic acid solution of η1nh1.58 was prepared, and acetic anhydride and pyridine in an amount of 0.2 equivalents of the amic acid unit, as well as a small amount of NMP, were added for partial cyclization. This solution (polymer concentration 15.6%, solution viscosity 2530 ρoise) was wet-spun in substantially the same manner as in Example 1, chemically cyclized, and then dried under vacuum at 550°C under a nitrogen atmosphere.
This example shows the production of a uniaxially stretched copolyimide film in which the diamine component is benzidine and the acid anhydride components are PMDA 40 mol % and DEDA 60 mol %.

The remainder of the spinning dope used in Example 1 was taken, cooled to -10°C in a dry ice-acetone bath, and mixed with 2.0 equivalents of amic acid units of acetic anhydride, 1.
A mixture of pyridine and an appropriate amount of NMP was added dropwise over 5 minutes, and stirring was continued for an additional 10 minutes (polymer concentration 7.5%). This solution was cast onto a glass plate and heated in an oven at 70°C for 1 hour. The polymer concentration of the chemically cyclized film obtained was about 85%. Peel off this film from the glass plate and
After cutting to width, it was stretched 1.6 times using a 200°C hot plate, and was further subjected to tension heat treatment for 5 seconds on a 400°C hot plate. This stretched film was placed in an oven at 450°C and treated in a relaxed state for 4 minutes. The tensile properties of the obtained film were as follows.

Patent applicant: Institute of Technology Director 19-

Claims (1)

[Claims] 4. Consisting of 4'-diphenyl ether tetracarboxylic dianhydride (B), Al6 (molar ratio) is 90/10
~20/80 -axis oriented wholly aromatic copolyimide molded product.