JPS5936662B2 - Method for producing aromatic polyamide crystalline complex - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a melt-formable aromatic polyamide crystalline complex.

In recent years, aromatic polyamide polymers have been widely used for clothing, materials, electrical insulation, etc. by being molded into fibers, films, resins, or papers due to their excellent heat resistance.

Conventionally, such aromatic polyamide polymers have extremely high melting points and cannot be melt-molded, and in order to be molded into fibers, films, or paper, the polymers must be prepared using dimethylformamide, N-methyl-2-pyrrolidone, tetramethylurea, etc. A so-called wet or dry molding method is employed in which the polymer solution is once dissolved in a polar organic solvent and the solvent is removed by extruding this polymer solution through a nozzle, die, or orifice into a liquid bath or gas stream.

However, this method requires expensive organic solvents;
It also has the disadvantage of requiring a large amount of expense for solvent recovery.

Compression molding of fine polymer powder has been attempted as a resin molding method, but it is difficult to produce uniform products. Against this background, the present inventors conducted extensive research on a method for molding aromatic polyamide polymers at low temperatures without requiring large amounts of solvent, and as a result, they developed a method to process aromatic polyamide polymers with a special organic solvent. The inventors have discovered that it is possible to produce a new compound that can be melt-molded at low temperatures.

That is, the gist of the present invention is to form a crystalline complex by contacting an aromatic polyamide polymer in which at least 75 mol% of the repeating units are m-phenylene isophthalamide with hexamethylphosphoramide or N-methyl 2-pyrrolidone. is formed, and then hexamethylphosphoramide or N-methyl 2-pyrrolidone not contained in the crystals is removed to produce an aromatic polyamide crystalline complex.

The crystalline complex of the present invention is a free-flowing substance, in which aromatic polym-phenylene isophthalamide and hexamethylphosphoramide or N-methyl 2-pyrrolidone coexist in the crystal lattice to form a novel crystalline complex. It seems that there are.

Such crystalline complexes are completely new chemical substances that have not been previously known to the world.

The method for producing the crystalline complex of the present invention will be specifically described below.

The organic solvent used in the production of the crystalline complex is hexamethylphosphoramide (hereinafter abbreviated as HMPA) or N-methyl 2-pyrrolidone (hereinafter abbreviated as NMP), and it is preferable to use it alone, but other solvents may be used. There is no problem even if used by mixing a small amount.

The form of the aromatic polyamide polymer (hereinafter sometimes abbreviated as PmIA) to be used is not particularly limited, and may be a powder, an unoriented or oriented fiber shaped by a conventional method, a film, or a resin. It can be used in any form.

The degree of polymerization of the polymer is not particularly limited, but preferably has a relative viscosity of 1.5 to 5.5 (1.0 in 100 cc of concentrated sulfuric acid at 25°C).
7 concentrations, hereinafter the same). Industrially, it is preferable to form a crystalline complex in a short time at a relatively low temperature, and for this purpose, the density of the polymer must be 1.39y/~ or less, and the thermal history must be maintained at 350°C or higher for 30 minutes or more. It is desirable that it is something that has not been received.

Such an aromatic polyamide polymer and HMPA or NM
A crystalline complex is formed by contacting with P for an appropriate period of time, preferably from 3 minutes to 60 hours, and more preferably from 5 minutes to 30 hours.

Any contact method may be used, but preferably a method in which the polymer absorbs an organic solvent or a method in which the polymer is dissolved in an organic solvent is used. Regarding the contact ratio between the polymer and the organic solvent at this time, in order to obtain a uniform crystalline complex, it is preferable that one or more organic solvents be present in a molar ratio.

On the other hand, since the use of a large amount of organic solvent is industrially disadvantageous in subsequent operations, it is preferable to use an amount that satisfies dissolution and absorption rates, that is, a ratio of about 5 times the amount of organic solvent per polymer. The temperature at which the polymer and solvent are brought into contact is not particularly limited, but it is desirable to bring the polymer into contact with the solvent in a range from room temperature to 130°C. Then, in order to remove excess organic solvent not contained in the crystalline complex,
Perform centrifugal desolvation, filtration, distillation, or drying treatment for concentration. Since the crystalline complex produced has a low melting point, the drying temperature is lower than the melting point, i.e. 130℃ when using HMPA.
It is preferable to adopt a temperature condition of 110°C or less, preferably 100°C or less when NMP is used. Specifically, the crystalline complex produced in this manner has the following characteristic values.

For example, polyphenylene isophthalamide powder with a relative viscosity of 3.2 is mixed with HMPA/polymer 10 in HMPA at 65°C.
/1 (weight ratio) for 60 hours, filtered, and vacuum dried at 60° C. for 24 hours to remove HMPA not included in the crystals, to obtain a crystalline complex. (The crystalline complex thus obtained is hereinafter referred to as complex A.) Complex A
f) The X-ray diffraction diagram is as shown in Table 1 and Figure 1.2.

For comparison, a diffraction diagram of polym-phenylene isophthalamide is also shown. (Fig. 1) Analysis of the crystal structure based on these results revealed that complex A belongs to the monoclinic system and consists of the following unit cell. a-10.48λ b-16.94λ c-11.30λ β=131.3λ The theoretical density is 1.3147/CTit.

The actual value was 1.24f when measured at 30℃ in decalin.
/ml. 1,20 to 1 depending on the conditions for forming the complex.
It fluctuates to 297/d. The theoretical density of the untreated polym-phenylene isophthalamide fiber is 1.477/d, and the actual value is 1.38y/CTit. Figure 2 shows the a-complex A. ．． B shows X-ray photographs of poly-m phenylene isophthalamide crystalline powder, c-oriented fibrous crystalline complex, and d-oriented crystallized poly-m phenylene isophthalamide fiber. Figure 3 shows 1 polym phenylene isophthalamide, 2
1 shows infrared absorption spectra of Complex A and 3HMPA.

The N-H stretching vibration of the polymer is 3300c7n-1, HM
The PA (:!) P=O stretching vibration appears at 1220c7n-1, while the N-H stretching vibration of complex A appears at 3200C.
It appears as 1rL=1 and is shifted to a 100°-1 lower wave number. In addition, the p=o stretching vibration appears at 1200CWL-1 and is shifted to a lower wavenumber of 20C1rL-1, and PO-
It is thought that a -1>HN bond is formed.

The melting point was measured using a PerkinElmer DSC model at a heating rate of 1.
This was done by measuring the DSC curve at 0°C/min.

The results are shown in Figure 4, and an endothermic peak was observed at 123°C. The melting point varies from about 111 to 129°C depending on the degree of polymerization of the polymer brought into contact with HMPA. This is the melting point of polym-phenylene isophthalamide polymer (420℃
), indicating that the crystalline complex of the present invention is completely new. The dynamic viscoelastic behavior of complex A is as shown in Figure 5, where there is a rapid rise in Tanδ from around 110°C, and a corresponding rise in Et.
It starts to decline rapidly.

It becomes impossible to measure the temperature above 132°C, and it is thought that flow occurs in this temperature range.

This phenomenon precludes the possibility of melt spinning the crystalline complexes of the present invention. When the solvent was removed from Complex A by extraction with boiling water, the molar ratio of polym-phenylene isophthalamide to HMPA was 1:1.88 (=weight ratio 1:1.42).

This value also changes depending on the conditions for forming the complex, and a polymer to solvent molar ratio of 0.4 to 1.88 can be obtained. ε The results of thermogravimetric analysis are shown in Figure 6, and it is 1/1 in air.
DSC curves were measured at a heating rate of 5° C./min.

230°C is the boiling point of HMPA, and the weight loss above 400°C is thought to be due to decomposition of the polymer, so approximately 55% by weight of HMPA is contained in the complex, which is similar to the value measured by boiling water extraction above. Match.

What is the crystallization index of complex A? Calculations were made as follows using an X-ray diffraction diagram as shown in the figure.

This varies from 0.63 to 0.77 depending on the conditions for forming the complex.

The crystal size was calculated as follows using the reflection spread of the meridian −L at 2θ=15.10.

λ: 1, 5418A k:0.89 θ:2θ=15.1 β: Half width after silicon correction From this, the crystal size was 69λ.

This also varies from 66 to 72λ depending on the conditions for forming the complex.
From the above results, it is considered that the crystalline complex A obtained in the present invention has a chemical structural formula with the following repeats. The crystalline complex of the present invention is particularly suitable as a starting material for fibers, films, nonwoven fabrics, binders, etc. by taking advantage of its low melting point.

In particular, a crystalline complex obtained by using oriented fibers in an aromatic polyamide polymer is useful as it exhibits excellent performance as a binder for nonwoven fabrics. This makes it possible to provide these products at a much lower cost than the conventional method of using poly(m-phenylene isophthalamide) itself. In the aromatic polyamide polymer of the present invention, at least 75 mol% of the repeating units are phenylene diamines obtained by reacting phenylenediamine and isophthalic acid halide such as isophthalic acid chloride by solution polymerization or interfacial polymerization. The target is those consisting of nylene isophthalamide.

If the copolymerization component exceeds 25 mol %, the crystallinity of the resulting crystalline complex decreases significantly, making it unfavorable for handling.

The components to be copolymerized as necessary include p-phenylene diamine, benzidine, 44' diaminodiphenyl ether, 447 diaminodiphenyl sulfone as the amine component, and terephthalic acid chloride, 1.4 as the acid component.
These are dicarboxylic acid halides such as naphthalene dicarboxylic acid chloride, 2.6 naphthalene dicarboxylic acid chloride, diphenyl sulfone 44' dicarboxylic acid chloride, and diphenyl ether 44' dicarboxylic acid chloride.
EXAMPLES The present invention will be specifically explained below with reference to Examples, but the present invention is not limited to the Examples.

Example 1 ★★
Relative viscosity is 3. ．． Polym-phenylene isophthalamide powder of No. 5 was immersed in HMPA at a ratio of HMPA/polymer = 3/1 (weight ratio) at 50°C for 2 hours, and after separating the polymer, it was soaked at 60°C for 5 hours at 2I1Hg. Drying was performed under reduced pressure of 271t1Hg. In the X-ray diffraction diagram of this product, strong and sharp absorption was observed at 2θ=14.0 s15.1, s19.1 line and 22.2θ. These are different from the absorption of polym-phenylene isophthalamide crystals. The boiling water extraction loss was 56 wt%, which is the loss of HMPA contained in the sample.
Despite containing such a large amount of solvent, it gave a dry and smooth feel and was easy to handle.

The melting point of the sample from the DSC curve was 116°C. The powder sample was well entrapped in the screw and had good spinnability.

The strength of the thread after extrusion with a syringe, taking it off, and removing the solvent in boiling water was 2.1 f/d.

Example 2 The same powder as in Example 1 was dissolved in dimethylacetamide, then dry spun using a conventional method, washed in boiling water, and dried to obtain an undrawn yarn.

This undrawn yarn had a strength of 0.8 f1/d1 and an elongation of 230%, and a density of 1.345 t/d. This was stretched to 3.6 times in hot water at 80° C. and heat treated on a hot plate at 1.0 times under the conditions shown in Table 1. Next, the fibers were separated after being immersed in HMPA and dried by centrifugation at 80° C. for 2 hours to remove the solvent. Although these samples retained their fibrous form, similar to Example 1, they exhibited absorption characteristic of crystalline complexes. These properties are shown in Table 2.
In the complex fiber obtained from the heat-treated yarn, orientation of complex crystals was also observed.

(Figure 2c) These fibrous complexes are suitable as starting materials for nonwoven fabrics and plate-shaped moldings.

Example 3 A film sample obtained by a conventional method from polym-phenylene isophthalamide with a relative viscosity of 3.2 was stretched 4 times in boiling water, and an oriented film was prepared in HMPA at 65°C with HMPA/polymer=
Soaked at 10/1 (weight ratio) for 60 hours, then soaked at 60°C for 2 hours.
Vacuum drying was performed at 3 mmHg for 4 hours.

The obtained sample was subjected to X-ray diffraction, and was rotated for 35 m while fully rotating.
Cylindrical photographs were taken with a camera radius of m. Many absorptions other than those shown in Table 1 were observed. 2θ=14 is on the 1st layer line,
2θ=15.1° is 2θ=26 on the meridian on the two-layer line
．． 5° was a reflection on the 3-layer line.

The melting point is 125℃ from the DSC curve, and the boiling water extraction amount is polymer/
The HMPA molar ratio was 1/1.76.

Density is 1.20y/Cni) Crystal size = 67 pieces, engineering t
/Ic=0.67. ～～～Example 4 A COOH-terminated oligomer with an average degree of polymerization of 5 was prepared at 65°C.
0 hours, immersed in HMPA with a HMPA/polymer = 10/1 (weight ratio), and then soaked at 60°C for 24 hours, 2 m
Vacuum drying was carried out at mHg.

The X-ray diffraction diagram was the same as in Example 1, and the melting point from the DSC curve was 111°C. When extracted with boiling water, the polymer/
HMPA = molar ratio 1/1.88 and density is 1.22
It was t/CIIL. Example 5 The same powder as in Example 1 was prepared using NMP/polymer = weight ratio of 10/1.
The polymer powder was immersed in NMP at 50° C. for 3 hours, and then the polymer powder was separated and dried under reduced pressure at 40° C. and 2 m 7 nHg for 5 hours.

The X-ray diffraction diagram (Fig. 1, 3) of this object shows that 2θ=16.2
A sharp absorption peculiar to −24.5° and 26.2 was observed.

These absorptions are different from those of polym-phenylene isophthalamide crystals, indicating that a complex crystal is formed. The sample had a dry feel, and the DSC curve showed a melting point of 90° C. and a boiling water extraction loss of 45 wt%. When the sample was melted at 110° C., a viscous melt with excellent stringiness was formed and could be melt-molded.

Example 6 A poly(m-phenylene inophthalamide) polymer having a terminal benzene ring with a polymerization degree of 5 was NM at 30°C for 3 hours.
It was immersed in NMP at a weight ratio of P/polymer = 3/1 and then vacuum dried at 2 m7 nHg for 5 hours at 40°C.

The melting point of the obtained crystalline complex was 65°C. Example
A polymer powder with a relative viscosity of 3.5 obtained by low-temperature solution polymerization of 7m phenylene diamine and isophthalic acid chloride/terephthalic acid chloride 90/10 (molar ratio) was HM
It was dissolved in PA at 60°C, then concentrated under reduced pressure at 40°C, and dried at 40°C under reduced pressure of 2 mmHg for 12 hours to obtain a free-flowing powder.

It was confirmed from the X-ray diffraction diagram that complex crystals were formed.

The boiling water extraction loss of this product was 50.5 wt%, and the DS
The melting point measured from curve C was 115°C.

When melted at 130°C, a viscous melt was obtained and had excellent moldability.

[Brief explanation of the drawing]

FIG. 1 is an X-ray diffraction diagram of the complex of the present invention, poly-m-phenylene isophthalamide, and FIG. 2 is an X-ray photograph of the complex of the present invention, poly-m-phenylene isophthalamide and fibers thereof.
Figure 3 shows the infrared absorption spectrum of the complex of the present invention, polym-phenylene isophthalamide, HMPA, Figures 4 and 6 show the DSC curve of the complex of the present invention, and Figure 5 shows the dynamic viscosity of the complex of the present invention. The elastic diagram and Figure T each show an X-ray diffraction diagram showing the crystallization index of the complex of the present invention.

Claims (1)

[Claims] 1. An aromatic polyamide polymer in which at least 75 mol% of the repeating structural units are m-phenylene isophthalamide is brought into contact with hexamethylphosphoramide or N-methyl 2-pyrrolidone to form a crystalline complex, and then No hexamethylphosphoramide or N-methyl 2
A method for producing an aromatic polyamide crystalline complex, characterized by removing pyrrolidone.