JP2732879B2 - Wholly aromatic copolymer polyamide - Google Patents

Description

The present invention relates to a novel wholly aromatic polyamide (hereinafter, referred to as aramid) having excellent mechanical properties such as strength and modulus, and having high heat resistance and chemical resistance. It is. More specifically, the present invention relates to a copolymer which is soluble in an organic polar solvent and has good processability.

[Prior Art] A wholly aromatic polyamide is widely used for fibers, films and the like by utilizing high strength, high modulus and high heat resistance. In particular, para-type aramid poly-p-phenyleneterephthalamide (hereinafter referred to as PPTA) is an industrial material,
Utilizing its features in protective equipment, etc., it is the mainstream of aramid.

However, regarding PPTA production and spin molding, there is a problem due to the rigidity of the molecule. For example, hexamethylphosphortriamide, which is highly toxic to living organisms, must be used as a polymerization reaction solvent. In addition, a liquid crystalline spinning solution must be prepared with concentrated sulfuric acid to perform so-called liquid crystal spinning. In addition, a large amount of neutralizing agent is required to neutralize the sulfuric acid, and inorganic ions are mixed into the product from the neutralizing agent, thereby deteriorating the quality of the product. It is also disadvantageous in terms of the process.

On the other hand, an attempt to simplify the process by preparing an isotropic spinning dope using a general organic polar solvent as a polymerization solvent has also been proposed. Specifically, a method of improving the solubility by copolymerizing an ether bond in a molecular chain (for example, Japanese Patent Laid-Open No.
-76386, JP-A-51-134743, JP-A-51-136916
No., JP-A-61-252229, JP-A-62-27431, JP-A-62-27431
2-225530, JP-A-62-177022, JP-A-62-177023
And the like have been proposed. Of these, p-
A wholly aromatic copolymer polyamide obtained by copolymerizing phenylenediamine (hereinafter referred to as PPDA) and 3,4'-diaminodiphenyl ether (hereinafter referred to as 3,4'-DAPE) has strength, rigidity,
It is a polymer with excellent chemical resistance, and N-methylpyrrolidone, which is a common organic polar solvent, can be used as a polymerization reaction solvent. Moreover, molding such as spinning can be directly performed using the polymer solution after the polymerization reaction. The process can be greatly improved.

Introducing such a flexible bond, an ether bond, into the polymer chain is an effective means in this respect. However, as can be inferred from the primary structure of the polymer, it is necessary to introduce properties such as heat resistance and rigidity. It has not yet achieved sufficient performance. At present, no wholly aromatic polyamide has been provided yet, which requires a higher degree of mechanical properties and heat resistance, and which is soluble in an organic solvent and can be used in a simple production process.

[Constitution of the Invention] As a result of earnestly examining copolymerized aramid having better mechanical properties while maintaining solubility in a solvent at the polymerization reaction stage, conventional PPDA, 3,4'-DAPE and terephthalic acid chloride It has been found that the introduction of m-tolidine having a rigid structure as the third diamine into the copolymerized aramid (hereinafter referred to as TPC) significantly improves the performance, and has led to the present invention.

That is, the present invention relates to a wholly aromatic copolymer polyamide containing terephthalic acid as an acid component and m-tolidine (A), paraphenylenediamine (B) and 3,4'-diaminodiphenyl ether (C) as amine components. Thus, it is a wholly aromatic copolymer polyamide in which the molar ratio of the amine components A, B and C is within the range HIJKLM shown in the triangular diagram (FIG. 1). A is m-tolidine, B
Represents a component of paraphenylenediamine (PPDA), and C represents a component of 3,4'-diaminodiphenyl ether (3,4'-DAPE). Each point of HM shows the following composition, respectively.

If the composition is out of this range, the solubility in the reaction solvent is poor and a polymer having a sufficient degree of polymerization cannot be obtained. Moreover, even if it is obtained, the performance of the molded product is inferior and the industrial value is poor.

Examples of the method for producing the copolymerized aramid include known methods such as melt polymerization, solid-phase polymerization, interfacial polymerization, and solution polymerization, and the solution polymerization method is particularly preferred. The reaction solvent is selected from dimethylformamide, dimethylacetamide, N-methylpyrrolidone, N-methylcaprolactam, dimethylsulfone, hexamethylphosphortriamide, tetramethylurea, etc., which are generally known as known organic polar solvents. At least one kind can be used as a main component.

In this case, a known inorganic salt may be added in an appropriate amount before, during, or at the end of the polymerization in order to increase the solubility.
Examples of such salts include lithium chloride and calcium chloride. In addition, the reaction between the acid component and the diamine component is performed in substantially equimolar ratio, but any one of the components can be used in excess for controlling the degree of polymerization. Further, a monofunctional acid component or amine component may be used as a terminal blocking agent.

Further, an aliphatic or aromatic amine or a quaternary ammonium salt may be used in combination for capturing an acid such as hydrogen chloride generated by the reaction.

After completion of the reaction, if necessary, a basic inorganic compound such as sodium hydroxide, potassium hydroxide, calcium hydroxide, calcium oxide or the like is added for neutralization.

The concentration of the polymer formed in the polymerization reaction relative to the solvent is important. In order to obtain a homogeneous polymer having a high degree of polymerization, the concentration of the produced polymer is preferably 20% by weight or less. In particular, a range of a few% to 10% is advantageous for obtaining a stable polymer. In particular, since the viscosity of the solution of the polymer of the present invention is high, it is necessary to optimize the degree of polymerization of the polymer and the solution concentration. The intrinsic viscosity is preferably 1.5 or more and 10 or less, more preferably 2.0 or more and 8 or less.

The reaction conditions do not require any special restrictions. The reaction between the acid halide and the diamine is generally rapid, and the reaction temperature is, for example, -25 to 100C, preferably -10 to 80C. Needless to say, foreign substances that hinder the reaction, such as water mixed in the reaction system, must be avoided.

The copolymerized aramid thus obtained can be put into a solvent such as alcohol or water, re-precipitated and taken out in the form of pulp, which can be dissolved again in another solvent and subjected to molding. The solution obtained by the polymerization reaction may be used as it is as a molding solution.

Particularly, the copolymerized aramid in the composition of the present invention is excellent in solubility and does not precipitate the polymer during the polymerization reaction. Therefore, it is preferably used directly as a solution for molding such as spinning. In this case, it is preferable to mold under a condition in which the molded product does not whiten due to coagulation, and for that purpose, it is preferable to use an inorganic salt such as a calcium chloride solution in combination.

Examples of the molding method include a method of first forming a solid pulp or a powder and then compression molding, film formation by a salivation method or a cast method of a polymer solution, spinning and film formation by a wet method, and the like. In the case of molding from a solution, fibers and films can be obtained by solidifying the extruded product once in a coagulation bath, followed by washing, drawing and heat treatment. In this case, an organic polar solvent / water system is preferably used as a coagulation bath.

[Effects of the Invention] In the present invention, by introducing a structural unit having a rigid skeleton called m-tolidine into a polymer, solubility in a solvent can be maintained and a more excellent high-performance molded article can be obtained. It is a very excellent copolymerized aramid.

The copolymerized aramid of the present invention can be prepared by the following methods: reprecipitation method, wet method, dry jet method, dry method, etc.
Processed into useful molded products such as hybrids. Further, it is a very important material in various fields as a rubber reinforcing material, a rope, a cord, and a resin reinforcing agent.

Hereinafter, the present invention will be described in more detail with reference to Examples, but it goes without saying that the present invention is not limited thereto.
The term “parts” in the examples means parts by weight, and the logarithmic viscosity ηinh, which is a measure of the degree of polymerization, is 0.5 g / dl in 98.5% by weight of concentrated sulfuric acid.
Was measured at 30 ° C. by an ordinary method.

Example 1 NMP1 was placed in a three-necked flask equipped with a sufficiently dried stirrer.
891.83 parts, 36.358 parts of m-tolidine (A) and PPDA (B)
After adding 13.890 parts and 35.683 parts of 3,4'-DAPE (C) at room temperature and dissolving in nitrogen, 86.926 parts of TPC were added with stirring. The viscosity gradually increased with the progress of the polymerization reaction. Finally, when the reaction was carried out at 80 ° C. for 60 minutes, a viscous polymer solution having extremely excellent transparency was obtained. The product is then treated with NM containing 22.5% by weight of calcium hydroxide.
P139.57 parts was added to carry out a neutralization reaction.

A part of the obtained polymer solution was taken in water, and the precipitated polymer was separated and dried, and the viscosity was measured.
= 4.34.

<Spinning> The obtained copolymerized aramid solution is placed in a cylinder equipped with a cap of 0.17 mm * 25 h and kept at 80 ° C. while keeping NMP at 30 wt%.
(Hereinafter referred to as dry jet spinning) through an air gap of 10 mm into a coagulation bath composed of an aqueous solution of
The spun yarn is washed with water, dried and then placed on a hot plate at 300 ° C and 520 ° C.
The film was stretched in two steps at a total stretching ratio of 20.8 at ℃ to obtain a 19-de filament.

The mechanical properties of this yarn are strength 18.3 (g / de) and elongation 2.1.
(%), The modulus was 950 (g / de), and the performance was significantly improved as compared with the case without m-tolidine (Comparative Example 1).

Comparative Example 1 The copolymerized aramid polymerized without adding m-tolidine had good transparency. This NMP solution was dry jet-spun by the method described in Example 1 to give a strength of 32de and a strength of 23.2.
A yarn having an elongation of 3.5 g and a modulus of 620 g / de was obtained.

Example 2 60 mol% of m-tolidine, 20 mol% of PPDA, 3,4'-DAPE20
Polymerization was carried out using a diamine component consisting of mol%. That is, m-tolidine 52.491 g, PPDA 8.913 g, 3,4'-DAPE1
Take 6.503 g in NMP1895.9 and dissolve at room temperature, then add TPC8
3.665 g are added with stirring, 60 minutes at room temperature, followed by 60
Polymerized for minutes. The reaction system became viscous as the polymerization progressed, but the reaction system was extremely transparent and no turbidity was observed.

After the polymerization reaction, 134.337 g of an NMP solution containing 22.5% of calcium hydroxide was gradually added to terminate the neutralization reaction. A part of the obtained solution was reprecipitated with water and the viscosity was measured. As a result, ηinh was 5.63.

The solution was subjected to wet jet spinning in the same manner as in Example 1 to obtain fibers of 28 denier. This thread has a strength of 17.1 g / de,
It was a tough fiber showing physical properties of elongation of 1.9% and modulus of 985 g / de.

Example 3 20 mol% of m-tolidine, 40 mol% of PPDA, 40 mol of 3,4'-DAPE
% Of the diamine component. That is, m
-Trizine 18.916 g, PPDA 10.271 g, 3,4'-DAPE 35.683 g
Was dissolved in NMP1887.44 g at room temperature, and 90.271 g of TPC was added with rapid stirring. 60 minutes at room temperature, then 80
The temperature was raised to ℃, and polymerization was carried out for 60 minutes. The solution of the obtained polymer was viscous with excellent transparency, and the viscosity was ηinh = 5.21.

This copolymerized aramid was spun into a yarn by the method shown in Example 1 and had a strength of 21.3 g / de and an elongation of 2.2 at 20 denier.
%, The modulus was 890 g / de, and the physical properties were significantly improved by the addition of m-tolidine.

Examples 4 to 15 Next, the results of evaluating the solubility of the polymer solution by changing the composition in various ways are shown. Except for changing the composition in each case, the method of Example 1 was used.

When the solution turbidity of the polymer becomes cloudy in the early stage and the middle stage of the polymerization reaction, ×, in the late stage of the reaction, Δ,
Good transparency without turbidity was indicated by a circle. All were judged visually. Table 1 shows the evaluation results.

[Brief description of the drawings]

FIG. 1 shows a three-component composition diagram of A (m-tolidine), B (p-phenylenediamine), and C (3,4'-diaminodiphenylamine). The portion surrounded by the solid line in the triangular diagram is a particularly preferred range of the present invention.

Claims (1)

(57) [Claims] 1. A wholly aromatic copolymer polyamide comprising terephthalic acid as an acid component and m-tolidine (A), paraphenylenediamine (B) and 3,4'-diaminodiphenyl ether (C) as amine components. , The amine components A and B
And the molar ratio of C are in the range HIJKLM shown in the triangular diagram (FIG. 1).
The wholly aromatic copolymer polyamide inside.