JPS63145414A - Modified poly-para-phenylene benzobisthiazole yarn and production thereof - Google Patents

Abstract

PURPOSE:To obtain the titled yarn having excellent adhesivity to matrix resin without damaging high modulus and high strength, by oxidizing poly-para- phenylene benzothiazole yarn in a gas phase and modifying the main structure unit thereof. CONSTITUTION:Poly-para-phenylene benzothiazole (hereinafter abbreviate PBT) yarn consisting of a unit shown by formula I is oxidized in a gas phase or in liquid phase and >=5mol% unit shown by formula I is modified into a unit shown by formula II (X and Y are 0-2 integer with the proviso that a case where both X and Y are O is omitted) to give the aimed yarn. PBT of raw material, for example, is obtained by subjecting 2,5-dithiol-1,4 phenylenediaminediammonium chloride and terephthalic acid to polycondensation in a polyphosphoric acid solvent at high temperature. In oxidizing PBT in a liquid phase, an oxidizing agent of organic peroxide type such as peracetic acid, etc., is preferably used.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention provides a novel poly-para-phenylenebenzobisthiazole fiber having improved adhesion to a matrix resin, high modulus and high strength, and a method for producing the same. Regarding.

[Conventional technology]

In recent years, high modulus and high strength fibers using organic polymers have been used as reinforcing fibers for various composite materials such as tire cords and structural materials for aviation, as well as various belts, ropes, protective materials, sporting goods, etc. Development and research is progressing with the aim of replacing asbestos and reinforcing cement. Methods for producing such high modulus and high strength fibers can be roughly divided into two methods: methods in which polymers with a relatively flexible molecular chain structure are highly oriented and crystallized by ultra-stretching, etc., and methods in which polymers with a rigid linear chain structure are obtained. It is divided into two methods: methods using molecules. As typical examples of these, the former is coated with highly polymerized polyethylene, and the latter is coated with aramid fibers such as polyphenylene terephthalamide.

However, the former high-strength fibers made of flexible polymers generally have a low melting point and poor heat resistance, so there are limits to their applicability. On the other hand, the latter high-strength fibers made of rigid linear polymers have high heat resistance and excellent chemical resistance. Fibers made of polyamide, fully aromatic polyester, polyazomethine, and aromatic polymers having a heterocycle in the main chain are known. In particular, polybenzothiazole fiber, which is an aromatic polymer having a heterocycle in its main chain, has been found to have the highest modulus among aluminium-based fibers, which is comparable to carbon fiber. This is expected to be able to compensate for the shortcomings (poor impact resistance). However, when such high-modulus, high-strength fibers are used as composite materials, in addition to the modulus and strength of the fibers themselves, the adhesion with the matrix resin is extremely important, and such polybenzothiazole fibers are sufficiently satisfactory in terms of this adhesion. However, when used as a composite material, the high modulus of the fiber itself cannot be fully demonstrated.

[Problem that the invention seeks to solve]

An object of the present invention is to provide a novel fiber that has excellent adhesiveness to a matrix resin without impairing the high modulus and high strength of the poly-para-phenylenebenzobisthiazole fiber.

Means for Solving Problem C] As a result of intensive studies to achieve the object of the present invention, the present inventors found that the structural unit of poly-para-phenylenebenzobisthiazole (hereinafter abbreviated as PBT) is The present inventors have discovered that this can be significantly improved.

That is, one aspect of the present invention has the following configuration.

(1) Represent by general formula. However, O in both X and Y is omitted (.) A modified poly-para-phenylene benzo mainly consisting of the structural units represented by Bisthiazole fiber.

(2) By treating poly-para-phenylenebenzobisthiazole fibers mainly consisting of the structural units represented by the general formula using either gas phase oxidation or liquid phase oxidation, the main structural units of the fibers can be Represent at least 5. However, O is excluded for both X and Y. ) A method for producing a modified poly-para-phenylenebenzobisthiazole fiber, characterized by modifying it into the structural unit represented by:

Hereinafter, nine aspects of the present invention will be described in detail.

PBT used in the present invention is mainly composed of structural units represented by the general formula. If the main component (constituent represented by general formula (A)) is less than 70 mol %, the modulus of the obtained polymer decreases, which is not preferable. It is more preferable that the proportion of the main component is 90 mol % or more because a high modulus can be obtained. If it is less than 30 mol%, other components 9, e.g. 2.5
(6) Contains an ether bond, a hyphenyl bond, a naphthyl bond, etc. such as benzimidazole, 2-6 penzobisoxazole, 3,4-oxydiphenylene terephthalamide, para-phenylene terephthalamide, or phenyl ether, or It may also be a copolymerized one.

Such PBT can be produced by polycondensation reaction using 2,5-dithiol-1,4 phenylene diammonium chloride and terephthalic acid at high temperature using polyphosphoric acid as a solvent. As an example of such dithiol-phenylene diammonium chloride, p-phenylene bisthiourea is synthesized using 2,5-diaminobenzene as a starting material.

It can then be produced from 2°6-diamitubenzobisthiazole obtained as a result of a cyclization reaction with bromine or the like.

PBT fibers are produced by preparing a 5-10% solution of PBT using methanesulfonic acid alone, a methanesulfonic acid/chlorosulfonic acid mixed solvent, or a polyphosphoric acid solvent. It can be obtained by spinning.

At this time, 1 normal water (cold water) alone was used as the coagulation bath.

Alternatively, water/methanesulfonic acid, or in some cases methanol/methanesulfonic acid, can also be used. After spinning, t6! The fibers are washed with water or methanol, and if necessary, neutralized with dilute sodium bicarbonate or the like. After that, it is stretched in warm water, dried and rolled up. After that 300~6
High modulus PBT fibers can be obtained by drawing at a high temperature of 50°C.

The effect of the present invention is greater when the PBT fiber used in the present invention is an ultrafine fiber, and as an ultrafine fiber, a single fiber fineness of 0.5 denier or less is preferable. The reason for this is that by making the fibers ultra-fine, it is possible to obtain fibers with even higher modulus and strength, ■ have greater flexibility (bending resistance), ■ reduce the amount of voids contained, and ■ expand the fiber surface. The reaction interface is increased and the oxidation reaction can be carried out to the inside of the fiber.

Such ultrafine fibers can be produced by direct spinning using a semi-dry/semi-wet method using a spindle with a small pore diameter, or by spinning the sea and island components of a homogeneous solvent system or a different solvent system through separate channels. A sea component dissolution method of polymer array fibers obtained by so-called solution-type composite spinning, or sea components, which are integrated just before the guide and discharge port,
It is also possible to use a method such as a method of dissolving the non-dispersed component (sea component) of mixed spun fibers using a polymer blend of the island component.

The modified PBT fiber of the present invention is obtained by oxidizing such PBT using either the gas phase oxidation or liquid phase oxidation method described below. However, 0 is excluded for both X and Y. ) refers to a product modified by the structural unit shown.

Even if side reactions such as addition of a hydroxyl group to the benzene ring occur during such modification, the effects of the present invention will not be impaired in any way.

Here, the proportion of the preferable structural units of the general formula (B) in all the structural units of the general formula (B) (hereinafter such a proportion is referred to as the sulfonation rate in a broad sense in the present invention) is 5 mol%.
If it is less than 1, the improvement in adhesiveness of the present invention cannot be expected. Therefore, the sulfonation rate is at least 5 mol% or more, preferably 10 mol% or more, more preferably 20 mol% or more, and the finer the fineness of the ultrafine fibers, the easier it is to obtain a high sulfonation rate.

In addition, such modification not only improves adhesion but also imparts hydrophilicity and makes fibrillation less likely to occur.

Now, regarding the oxidation method used in the present invention.

Either gas phase oxidation or liquid phase oxidation may be used. In the case of gas phase oxidation, corona discharge treatment, Ar plasma treatment, 0. Plasma treatment or the like can be used.

In the case of liquid phase oxidation, the oxidizing agent (
(However, sulfuric acid, persulfuric acid, and nitric acid are excluded), among which peracetic acid, perbenzoic acid, potassium permanganate, sodium perborate, sodium peroxide pyrophosphate,
Peroxide systems such as sodium peroxide and hydrogen peroxide, or chlorine-containing systems such as sodium hypochlorite, calcium hypochlorite, and sodium chlorite are preferred. Among these, peroxide-based organic peracids such as peracetic acid and perbenzoic acid are particularly preferable because they cause very little cleavage of the main chain and generation of side reactions.

The conditions for treatment with such an oxidizing agent vary depending on the fineness (specific surface area) of the fiber, the type, concentration, temperature, etc. of the oxidizing agent used, and cannot be absolutely limited, but in the case of peracetic acid, a high sulfonation rate can be achieved even at room temperature. It is possible to do so.

〔Example〕

Example 1 2.5-dithiol-1,4-phenylenediammonium chloride and terephthalic acid were subjected to a stepwise polycondensation reaction at a reaction temperature of 100 to 200°C under an argon gas atmosphere using polyphosphoric acid as a polymerization solvent, PBT concentration approx. 5
After making a % polyphosphoric acid solution, PBT was isolated.

Next, the PBT was redissolved in methanesulfonic acid to prepare a 10% PBT solution as a spinning stock solution, and then spun using a semi-dry-semi-wet method. On this occasion.

Cold water at 0°C was used as the coagulation bath. The coagulated fibers were subsequently washed with water, neutralized with dilute sodium bicarbonate, dried at room temperature and wound up.

Thereafter, it was stretched at a high temperature of 450° C. under a nitrogen atmosphere.

The fineness of the obtained PBT fiber was 2.5 denier.

Next, the PBT fibers were placed in a 9% peracetic acid bath at 50°C for 5 minutes.
After being treated for a minute, it was washed with water, neutralized, washed with water, and dried.

After such oxidation treatment, the PBT fibers are processed into solid high-resolution NM.
Identified by R and ESCA (electron spectroscopy for chemical analysis),
Quantitative analysis revealed that the sulfur atoms constituting the thiazole ring of phenylenebenzobisthiazole, the main constituent unit of PBTO, were oxidized.

The total sulfonation rate is 15.
It was mol%.

The strand strength of the oxidized modified PBT fiber of the present invention was measured in accordance with the resin-impregnated strand test method specified in J I 5-R-7601, and the strand strength was 240 kg/mm'' and the modulus was 2.5 x 10.
'kg/mm2.

On the other hand, the strand strength of untreated PBTI61i fiber was 150
kg/mm", modulus 1.6xlO' kg/m
m”.

Example 2 Using a 6% polyphosphoric acid solution of PBT synthesized in the same manner as in Example 1 as a spinning dope, spinning was performed in the same manner as in Example 1 using a 0.05 mm spinneret, followed by heat setting treatment and .3d PBT ultrafine fibers were obtained.

Next, it was treated in a 40% peracetic acid bath at 60° C. for 10 minutes, and then washed with water, neutralized, washed with water, and dried. The sulfonation rate of the obtained modified PBT ultrafine fiber was 50 mol%.

Next, to measure the adhesive strength between the modified PBTPiA fine fibers and the resin, a unidirectional prepreg was prepared using "Chinsononox" 221/boron trifluoride monoethylamine, and the interlaminar shear strength was measured using a three-point bending short beam method. However, a high strength of 15.5 kg/mm2 was obtained.

On the other hand, the interlaminar shear strength of untreated PBT microfiber is 7.2k.
g/mm".

C Effect of the invention] The modified poly-para-phenylenebenzobisthiazole fiber of the present invention has high modulus and high tenacity, and has heat resistance,
It also has excellent chemical resistance.

Furthermore, it has excellent adhesion with matrix resins, so it can be used as a material for various structural materials such as tire cords and reinforcing fibers for various engineering plastics, as a material for electronic and electrical equipment, as well as for sports equipment and cement reinforcement. It can also be preferably applied to

Claims (3)

[Claims] (1) General formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼・・・・・・(A) and ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼・・・・・・(B) (Here, X and Y are 0 , represents an integer of 1 or 2,
However, 0 is excluded for both X and Y. ) A modified poly-para-phenylenebenzobisthiazole fiber mainly consisting of the structural units represented by formula (B) and containing at least 5 mol% of the structural units of general formula (B) in all the structural units. (2) The modified poly-para-phenylenebenzobisthiazole fiber according to claim 1, wherein in general formula (B), X=Y=2. (3) General formula▲There are mathematical formulas, chemical formulas, tables, etc.▼・・・・・・(A) Poly-para-phenylenebenzobisthiazole fibers mainly composed of the structural units shown in the formula are either gas-phase oxidation or liquid-phase oxidation. By processing using this method, at least 5 mol% of the main constituent units of the fiber are converted to a general formula ▲ mathematical formula, chemical formula, table, etc. ▼ (B) (where X, Y are represents an integer of 0, 1, or 2,
However, 0 is excluded for both X and Y. ) A method for producing a modified poly-para-phenylenebenzobisthiazole fiber, characterized by modifying it into the structural unit represented by: