JPH01314724A - Copolyimide yarn - Google Patents

Abstract

PURPOSE:To obtain the subject yarn suitable for electric insulating material, fire proofing wear, filter or interior material of vehicles, etc., having excellent continuity of heat resistance, nonflammability and dimensional stability at high temperature, containing diaminodiphenylether is diamine component and specific component of acid anhydride component. CONSTITUTION:The aimed fiber is composed of 4,4'-diaminodiphenylether as diamine component and acid anhydride component of (A) pyromellitic dianhydride and (B) 3,3', 4,4'-benzophenone tetracarboxylic dianhydride and/or 3,3', 4,4'-biphenyltetracarboxylic dianhydride and fraction of the component A in the acid anhydride is 85-35mol%. To obtain said fiber, at first above monomers are reacted to form polyamic acid solution, then spun to fiber by wet or dry spinning method and at last converted to polyimide by cyclization with heat or chemical means.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a copolyimide fiber with excellent heat resistance. More specifically, the present invention relates to a polyimide fiber which has both extremely excellent heat resistance life and moderate high temperature dimensional stability.

[Prior Art] Fully aromatic polyimide has the highest heat resistance among organic polymers, and several molded products have already been put into practical use by taking advantage of this characteristic. Poly(4,4°-oxydiphenylenepyromellitimide), which is a typical polymer, is famous for its film (trade name: Kapton).
It was once considered as a fiber (Special Publication No. 42-2936
Publication No.).

Although this fiber has extremely high flame retardancy and thermal dimensional stability, in the case of fibers made by the usual thermal cyclization method,
It was found that the retention of tensile properties, V, or heat resistance life after long-term exposure to relatively high temperatures was quite poor.

[Problems to be Solved by the Invention] Therefore, fibers that have excellent heat-resistant life, high-temperature dimensional stability, and flame retardancy are particularly desired.

As a result of considering why the heat resistance life of the poly(4,4°-oxydiphenylene pyromellitimide>S fiber) is poor, the present inventor found that this fiber is highly crystalline and that thermal crystallization occurs during heat resistance test treatment. We speculated that the reason for this must be a decrease in physical properties as the chemical reaction progresses, that is, so-called crystallization deterioration.Therefore, copolymerization of the monomers with a certain degree of crystallinity to reduce the crystallinity to some extent would be effective in improving the heat-resistant life. As a result of intensive study in this direction, we discovered that the above goal could be achieved by copolymerizing specific acid anhydride components in a specific ratio, and thus arrived at the present invention.

[Means for Solving the Problems] That is, in the present invention, the diamine component is 4,4°-diaminodiphenyl ether, and the acid anhydride component is pyromellitic anhydride (A> and 3,3°, 4,4°-benzophenone). Tetracarboxylic dianhydride and/or 3,3″, 4,4
It is a copolyimide fiber made of °-biphenyltetracarboxylic dianhydride and characterized in that the ratio of A in the acid anhydride component is 85 to 35 mol%.

The present invention will be explained in more detail below.

The diamine component constituting the copolyimide fiber of the present invention is
4,4'-diaminodiphenyl ether. Also,
One of the acid anhydride components is always pyromellitic anhydride (
PMDA) is used. Other acid anhydride components are 3, 3°, 4
, 4°-benzophenonetetracarboxylic dianhydride (B
Ding DA> and/or 3,3゛, ,! l, 4'-
It is biphenyltetracarboxylic dianhydride (BPDA). When the ratio of PMDA in the acid anhydride component exceeds 85 mol%, when fibers are made by the usual thermal cyclization method, the thermal dimensional stability is poor, perhaps because the crystallinity is too high, but the heat resistance life is reduced. do. In addition, PMDA in the acid anhydride component
When the ratio of 35 mol % is unvortexed, the polymer has significantly poor thermal dimensional stability due to poor quality or extremely low crystallinity. To obtain the copolyimide fiber of the present invention, first, the above-mentioned monomers are polymerized in an amide solvent to create a polyamic acid solution, then spun by a wet or dry method, and finally by thermal or chemical means. It is cyclized and converted into polyimide.

N-methylpyrrolidone (NMP) as an amide solvent
, N,N-dimethylformamide, N,N-dimethylacetamide, etc., and a known low-temperature solution polymerization method is used for polymerization.

Wet spinning typically uses an aqueous coagulation bath. In this case, the spinning stock solution may be the polyamic acid solution itself obtained by polymerization, but the present inventors have previously proposed
It is more preferable to use the method proposed in the publication, that is, to use a partially cyclized polyamic acid solution in which a part of the amic acid units are chemically imidized, because it provides a coagulated yarn with good transparency and fewer voids.

The coagulated filament is then cyclized by thermal or chemical means,
The desired copolyimide fiber can be obtained.

As the cyclization method, thermal cyclization is usually more preferable from the economic point of view. The cyclized copolyimide fiber is finally hot-stretched or heat-treated at high temperatures to improve its mechanical properties, but if this hot-stretching or heat treatment is carried out at a high temperature of 4 o'clock or higher, the thermal crystallization of the polymer will be excessive. This progresses and causes a decrease in heat resistance life. Therefore, the hot stretching or heat treatment temperature is 400
"C or less is preferable.

The copolyimide fiber of the present invention has an extremely excellent heat-resistant life, and also has high flame retardancy and dimensional stability at high temperatures. It also has practical mechanical properties, as well as chemical resistance and
It also has excellent radiation resistance.

The polyimide fiber of the present invention may be in the form of staple, filament, or pulp, and may also be woven, knitted, nonwoven, or paper made of these, or
It also includes blended fabrics with Haku fibers and mixed fabrics.

[Example] The present invention will be explained in further detail by the following Examples and Comparative Examples.

In the example, the intrinsic viscosity (7 inh) of the polyamic acid is boria 0.59/solvent 100 m! ! The polymer solution was diluted with NMP to give a ratio of .

In addition, the tensile properties were measured using Tensilon manufactured by Toyo Baldwin Co., Ltd., and the tensile speed was 50 for a yarn with a sample length of 100 m.
The measurement was performed under the conditions of m/min.

Example 1 This example shows the production of a copolyimide fiber whose diamine component is 4,4''-diaminodiphenyl ether (DA) and whose anhydride components are 60 mol% PMDA and 40 mol% BTDA, and its properties.

In NMP, 0.25 equivalents of amic acid units of acetic anhydride and pyridine were added to a 7 inch h2.56 polyamic acid solution obtained by reacting DA with PMDA and BTDA at the above ratio to obtain a polymer concentration of 12% and a solution viscosity of 1080. A partially cyclized polymer solution of poise (25°C) was obtained.

This solution was mixed with N using a 0.08 mΦ, 20-hole cap.
Wet spinning in a 25°C coagulation bath consisting of MP/water (volume ratio 25/75) at a spinning speed of 10 m/min),
The film was then stretched to 1.4 times in water and then wound onto a glass bobbin. After drying by heating in an air oven at 80'C for 30 minutes, the temperature was raised to 280'C over about 20 minutes in the same oven, and thermal cyclization was proceeded by heating at the same temperature for 30 minutes.

This thermocyclized yarn was stretched 1.3 times using a hot plate at 350°C, and the yarn quality was 73 denier and strength 3°22/d.
, elongation 19.4%, elastic modulus 529/d, and 2 in air.
After being heated to 90'C for 112 hours, the fiber strength was 3.19g/
d (retention rate 99%), elongation 17.7% (retention rate 91%)
) and the heat resistance life was significantly superior. In addition, the shrinkage rate of this drawn yarn after treatment at 450° C. for 15 minutes was 1.4%, indicating extremely high high-temperature dimensional stability.

The yarn obtained by drawing the above thermocyclized system 2.8 times using a hot plate at 420'C has a fineness of 35 denier, a strength of 7.179/d, an elongation of 11.5%, and an elastic modulus of 92σ/d. in the air, 29
After treatment at 0'C for 112 hours, the strength retention rate was 70% and the elongation retention rate was 78%.

Comparative Example 1 This comparative example shows a production example of homopolyimide fibers made of DA and PMDA and its characteristics.

η1nh3 obtained by reacting DA and PMDA in NMP
．． A partially cyclized polymer solution having a polymer concentration of 7.0%, a degree of partial cyclization of 25%, and a solution viscosity of 570 poise (at 25° C.) was obtained from the polyamic acid solution of No. 81 using the recipe of Example 1.

This solution was wet-spun using exactly the same equipment and recipe as in Example 1, and then thermally cyclized.

This thermocyclized system was stretched 1.5 times using a hot plate at 430°C, and the yarn quality was 38 denier and strength 4.19 s/
d, elongation 6.71%, elastic modulus 76 SJ/d, and strength 1.7 after treatment in air at 290°C for 1112 hours.
7y/d (retention rate 42%), elongation 2.74% (retention rate 41%).The drawn yarn with a hot plate temperature of 3'50°C and a magnification of 1.2x has a fineness of 47 denier and a strength of 2.999
/d, elongation 9°10%, elastic modulus 51/d, strength retention rate 58% after treatment in air for 290'C1112 hours,
The elongation retention rate was 50% and the heat resistance life was only slightly improved.

Comparative Example 2 This comparative example shows a production example of homopolyimide fibers made of DA and BTDA and its characteristics.

η1nh1 obtained by reacting DA and BTDA in NMP
, 42, a polymer solution having a polymer concentration of 16% and a degree of partial cyclization of 30% was obtained using the formulation of Example 1.

This solution was wet-spun according to the recipe in the example, and then thermally cyclized.

This thermally cyclized yarn was drawn 2.5 times using a hot plate at 360'C and had a fineness of 35 denier, a strength of 3.47 y/d, an elongation of 31.2%, and an elastic modulus of 479/d. Medium, 290
Although the heat resistance life is extremely excellent, with a strength retention rate of 95% and an elongation retention rate of 103% after treatment at 1112 hours at °C,
Since it is an amorphous polymer, its thermal dimensional stability is poor, and 350
The shrinkage rate after treatment for 'C110 minutes was extremely high at 44%, and the yarns fused together at 4oo'C or more.

Example 2 In this example, the diamine component is DA and the acid anhydride component is PMD.
A manufacturing example and yarn properties of a copolyimide fiber consisting of 80 mol% A and 20 mol% BTDA are shown.

The monomers were reacted at the above ratio in NMP and η1nh2.3
0 polyamic acid was prepared, and then using the recipe of Example 1, the polymer concentration was 9.7%, the degree of partial cyclization was 25%, and the solution viscosity was 600.
A partially cyclized polymer solution of poise (25°C) was obtained.

This solution was wet-spun according to the recipe of Example 1 and then thermally cyclized.

This thermocyclized yarn was stretched 1.3 times using a hot plate at 350'C, and the yarn quality was 65 denier and 3.55 g in strength.
/d, elongation 15.3%, elastic modulus 589/d, strength retention rate 80% after treatment in air for 290'C1112 hours.
, the elongation retention rate was 80%. Further, the shrinkage rate after being left at 450'C for 5 minutes was 5.4%. 9 [Effects of the Invention] As mentioned above, the copolyimide fiber of the present invention has a long heat-resistant life,
It has particularly excellent flame retardancy and high-temperature dimensional stability, as well as practical mechanical properties, so it can be used as an electrical insulating material, for example.
It can be widely used in various industrial materials such as flame-retardant clothing, filters, and vehicle interior materials.

Claims (1)

[Claims] (1) The diamine component is 4,4'-diaminodiphenyl ether, and the acid anhydride component is pyromellitic anhydride (A) and 3
,3',4,4'-benzophenonetetracarboxylic dianhydride and/or 3,3',4,4'-biphenyltetracarboxylic dianhydride, and the ratio of A in the acid anhydride component is 85 A copolyimide fiber characterized in that it has a content of ~35 mol%.