JPS6239634A - Production of polyp-phenylene terephthalamide based film - Google Patents

Abstract

PURPOSE:To produce a transparent film having improved plane orientation, by forming an optically anisotropic dope consisting of polyp-phenylene trephthalamide based polymer and a strong acid into a film, converting the film into an optically isotropic dope, coagulating the dope and washing the coagulated dope. CONSTITUTION:A dope, consisting of a polyp-phenylene trephthalamide based polymer having >=2.5, preferably >=3.5 inherent viscosity and a solvent selected from sulfuric acid, chlorosulfuric acid and fluorosulfuric acid in >=98wt% concentration and having optical anisotropy at about ordinary temperature in >=10wt% concentration is formed into a film on a support surface, and the resultant film is made to absorb moisture in saturated steam, supersaturated steam or a gas containing misty water at >=45 deg. and converted into an optically isotropic dope, which is then coagulated and washed to remove the acid. The washed film is then dried to produce the aimed film.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to polyparaphenylene terephthalamide (hereinafter referred to as
Regarding the manufacturing method of a film consisting of PPTA),
More specifically, a PPTA film that is transparent and exhibits excellent mechanical properties in both the length direction (hereinafter referred to as the MD force direction) and the width direction (TD force direction) due to its excellent plane orientation, and can be obtained by a simple means. It concerns the manufacturing method.

(Prior art) A linearly coordinated aromatic polyamide represented by PPTA has particularly excellent crystallinity and a high melting point, and due to its rigid molecular structure, it has heat resistance and high mechanical strength. and
It is a polymer material that has received particular attention in recent years. It has also been reported that fibers spun from concentrated solutions exhibiting optical anisotropy exhibit high strength and modulus, and have already been put into practical use industrially, but there are few proposals for application to films. However, there are still no known examples of practical use.

Problems with PPTA include that its useful high molecular weight polymer is poorly soluble in organic solvents, and strong inorganic acids such as concentrated sulfuric acid must be used as a solvent. , for example, Special Public Interest Publication No. 56-4
No. 5421 discloses a unit that is soluble in organic solvents by copolymerizing a unit in which a halogen group is introduced into the aromatic nucleus of a linearly coordinating aromatic polyamide and an aromatic polyamide other than PPTA that does not have a substituent in the aromatic nucleus. Attempts have been made to obtain films from it. However, this method has the disadvantage that the cost is high because the 7-mer is expensive, and that it impairs the heat resistance and crystallinity of the linearly coordinated aromatic polyamide.

On the other hand, Japanese Patent Publication No. 59-14567 discloses a method of extruding an aromatic polyamide solution having optical anisotropy from a slit through a short air layer into a coagulation bath. Only the mechanical strength was strong, but the mechanical strength in the TD force direction perpendicular to the mechanical strength was extremely weak, and only a product that was easy to tear was obtained.

If the optically anisotropic dope of aromatic polyamide is simply extruded and solidified as it is, it will be excessively oriented in the extrusion direction, making it easy to fibrillate and weak in the TD force direction. Various film manufacturing methods have been studied to try to improve this problem.

For example, Japanese Patent Publication No. 57-35088 discloses that an aromatic polyamide solution having optical anisotropy is extruded from a ring die, simultaneously cast in a doped state in two axes using an inflation method, and then wet coagulated. It is said that an isotropic film can be obtained by doing this. However, this method has the disadvantage that it is difficult to obtain a film with uniform thickness and its mechanical strength is low.

Also, Japanese Patent Publication No. 59-5407, Japanese Patent Publication No. 54-132
No. 674 discloses that by mechanically applying a shearing force to an optically anisotropic or optically isotropic dope of a linear aromatic polyamide in a goo in a direction perpendicular to the extrusion direction,
Although it has been proposed to orient the material in two axes, ie, in the extrusion direction and in a direction perpendicular to the extrusion direction during extrusion, the structure of the die is complicated and there are difficulties in industrial implementation.

Furthermore, J, Appj! ,Pofym,Sc i,voA
, 27, No. 8, P, 2965-2985 (19
82) proposes that a biaxially oriented film can be obtained by extruding an optically anisotropic dope of PPTA from a ring die onto an oil-coated conical mandrel; The isotropic mechanical strength is low, and when drafted, the mechanical strength in the MD direction is high, but
The TD force direction was significantly lower.

Japanese Patent Publication No. 57-17886 discloses that an optically anisotropic dope of a linearly coordinated aromatic polyamide is heated until it becomes optically isotropic immediately before solidification, and then solidified to produce a transparent material with mechanical properties. It is described to obtain films that are isotropic. This method is an original method that goes against the conventional concept of achieving high performance by utilizing optically anisotropic doping, and it allows for the relaxation of the extreme uniaxial orientation of optically anisotropic doping. At the same time, it has been successfully avoided that the liquid crystal domain structure of the optically anisotropic dope remains even after the dope is extruded and solidifies as it is, resulting in an opaque film. However, as mentioned above, this method has no choice but to use concentrated sulfuric acid or other inorganic strong acids as a solvent, so the polymer decomposition occurs when the optically anisotropic dope is heated to a temperature at which it becomes optically isotropic. However, there is a problem in obtaining a high-strength film, and simply heating to form an optically isotropic dope and then extruding it will cause the flow orientation during extrusion to be more relaxed than in the case of an optically anisotropic dope. However, the viscosity is extremely high, making extrusion itself difficult.

(Problems to be Solved by the Invention) As described above, since the optically anisotropic dope has a domain structure in which polymers are aggregated as liquid crystals, the domain structure remains even when the dope is made into a film, making it difficult to obtain a film. The film becomes opaque. If you try to use an optically isotropic dope to avoid this, you can use a useful high molecular weight PPT.
A-based polymers have extremely high viscosity and cannot be formed into films unless the polymer concentration is approximately 5% by weight or less. Films formed from optically isotropic dopes at this concentration tend to form voids during coagulation and are mechanically difficult to form. The physical properties are also completely inadequate.

The purpose of the present invention is to use PPTA or PPTA-based polymers whose fibers have already been produced industrially to obtain a transparent film with excellent transparency as described above in a short time, and to further improve the film quality. Not only in the MD force direction,
The object of the present invention is to provide an industrial method for producing a film that is sufficiently oriented in the TD force direction and has high strength and modulus in both the longitudinal and lateral directions.

(Means for Solving the Problems) The concept of Japanese Patent Publication No. 17886/1986 described above uses a dope with a high polymer concentration, which is preferable for improving the mechanical properties of the film, while naturally forming a polymer with PPTA. By applying the lower viscosity of the dope associated with the liquid crystal phenomenon,
This method facilitates the melting, transport, and molding of the polymer, and makes the dope optically isotropic by heating it for a short period of time just before final solidification to obtain a transparent film.

The inventors of the present invention made a rapid study to apply this idea and overcome its shortcomings, and as a result of the accidental discovery of the phenomenon and elucidation of its mechanism, the following new film and its manufacturing method were developed to solve the above problems. They have discovered that this is the case, and have completed the present invention.

That is, the present invention provides a polyparaphenylene terephthalamide-based polymer having a logarithmic viscosity ηinh of 2.5 or more,
Optically anisotropic dope containing at least one solvent selected from the group consisting of sulfuric acid, chlorosulfuric acid, and fluorosulfuric acid at a concentration of 98ffif1% or more and having optical anisotropy at a temperature around room temperature or higher. The optically anisotropic dope is optically isotropic by forming it into a film on a supporting surface while maintaining the same temperature, and absorbing moisture in a gas containing saturated steam, supersaturated steam, or mist water at 45°C or higher. The present invention relates to a method for producing a polyvalent phenylene terephthalamide film, which comprises substantially converting the film into a polyvalent dope, coagulating it, and then washing it.

The film of the present invention is substantially composed of a PPTA system represented by +C-Qo-cOHN (◇-NH6. Here, the meaning of "substantially" refers to the constituent features and effects of the present invention. Polymers other than PPTA [e.g., poly(m-phenylene terephthalamide), poly=(p-
phenylene isophthalamide), poly(m-phenylene isophthalamide), poly(methylene terephthalamide), aliphatic polyamide, aliphatic polyamide, polyester, polyimide, polyurethane, polyurea, etc.], or other materials are blended with PPTA. Repeating units (e.g. nuclear substituted p-phenylene units, nuclear substituted or unsubstituted biphenylene units, 0-phenylene units, m
- phenylene units, (poly)methylene units, pyridylene units, bonding units such as esters, urethanes, ureas, ethers, thioethers, etc.) may be copolymerized.

If the degree of polymerization of the polymer of the present invention is too low, it will not be possible to obtain a film with good mechanical properties, which is the object of the present invention, so the logarithmic viscosity η1nh ( 100mj of sulfuric acid! 0.2g of polymer
A polymer with a degree of polymerization that gives a value measured at 30°C when dissolved is selected.

Suitable solvents for preparing the dope for forming the PPTA-based film of the present invention include sulfuric acid, chlorosulfuric acid, fluorosulfuric acid, or mixtures thereof at a concentration of 98% by weight or more. Sulfuric acid of 100% or more, ie, fuming sulfuric acid, trihalogenated acetic acid, etc., may be mixed and used within a range that does not impair the effects of the present invention.

The concentration of the polymer in the dope used in the present invention is preferably at least a concentration that exhibits optical anisotropy at temperatures around room temperature (approximately 20 to 30°C) or higher, and specifically, approximately 10% by weight. It is preferably used in an amount of about 12 M% or more. At polymer concentrations that do not exhibit optical anisotropy at room temperature or higher temperatures, the formed PPTA film often does not have favorable mechanical properties.There is no particular upper limit to the polymer concentration of the dope. However, it is usually less than 25% by weight, especially PP with high ηinh.
For TA-based polymers, 20% by weight or less is preferably used.

The dope of the present invention may contain conventional additives, such as fillers, light removers, UV stabilizers, heat stabilizers, antioxidants, pigments, solubilizing agents, and the like.

Whether the dope is optically anisotropic or optically isotropic can be determined by a known method, such as the method described in Japanese Patent Publication No. 50-8474, but the critical point depends on the type of solvent, temperature, polymer Since it depends on the concentration, degree of polymerization of the polymer, content of non-solvent, etc., it is possible to create an optically anisotropic dope by examining these relationships in advance.

The method of obtaining a transparent film with excellent mechanical properties according to the present invention involves forming a dope into a film on a support surface using a specific method, and then converting the dope from optically anisotropic to optically isotropic prior to solidification. It is something.

Specifically, an optically anisotropic dope formed into a film on a support surface is allowed to absorb moisture in a gas containing saturated steam, supersaturated steam, or mist water at 45° C. or higher prior to solidification.

From an economical point of view, air is the most preferable gas. Atomized water as used in the present invention refers to particles of water that float in the air among the condensed water that is produced by releasing water vapor at 100°C or higher into the air, or water that is generated by a commercially available humidifier. It shows fine water particles that are suspended in water, and excludes large particles that do not float in the air. This is because if large particles of water come into contact with the dope on the support surface, partial coagulation will begin, which is undesirable. A temperature of 45° C. or higher is usually used. Absorbing moisture at a temperature below 45° C. is not preferable because it will partially solidify, leading to polymer precipitation and loss of flatness of the film. In addition, when considering the decomposability of the polymer, it is generally desirable that the upper limit is not too high, and it is desirable that the temperature of the film-like dope is selected so as not to exceed 200°C. A more preferable temperature range for making the dope absorb moisture is 60-150°C.

As described above, a major feature of the present invention is that an optically anisotropic dope of a PPTA-based polymer can be made optically isotropic in a short time of several seconds or less by absorbing moisture in the dope with a gas containing a large amount of water at high temperature. . As a result, even when the thickness of the dope is thick, the polymer concentration in the dope is high, and the degree of polymerization is high, optically isotropic films can be easily produced industrially and without impairing the physical properties of the film. Can be formed into a film.

The mechanism by which optical isotropy occurs due to moisture absorption is not necessarily clear, but it is probably because the liquid crystal region of the PPTA polymer solvent system is considerably reduced due to a decrease in polymer concentration and solvent concentration due to moisture absorption.

If we attempt to achieve this optical isotropy by heating alone without moisture absorption, heating at high temperatures and for a long time will be required.
The resulting film also tends to have poor physical properties due to partial decomposition of the polymer.

In the present invention, examples of the dope coagulating liquid that can be used include water, dilute sulfuric acid containing about 70 M% or less, sodium hydroxide aqueous solution containing about 20% by weight or less, and aqueous ammonia, about 5% by weight or less.
These include 0% by weight or less sodium chloride aqueous solution and calcium chloride aqueous solution. The temperature of the coagulation bath is not particularly limited and is usually in the range of about -5 to 50°C.

Since the coagulated film as it is contains acid, it is necessary to wash and remove the acid as much as possible in order to produce a film whose mechanical properties are less likely to deteriorate due to heating. Specifically, it is desirable to remove the acid content to about 500 ppm or less. Water is usually used as the cleaning liquid, but if necessary, hot water may be used, or washing may be performed by neutralizing with an alkaline aqueous solution and then washing with water. Cleaning is carried out, for example, by running the film in a cleaning liquid or by spraying the cleaning liquid.

The washed film is then dried. Drying here refers to the operation of removing the cleaning liquid etc. adhering to the film. Any method may be used as long as the cleaning liquid etc. can be removed, such as air drying at room temperature or heating. Any method may be used, such as drying in an atmosphere of an inert gas such as air, nitrogen, or argon, drying on a heated roll, or drying in a heated atmosphere with a tenter. Further, in order to prevent the film from wrinkling, drying is preferably carried out under tension or at a constant length to limit shrinkage of the film.

The drying temperature is not particularly limited, but is preferably at least room temperature, and in order to effectively improve mechanical strength, it is preferably at a high temperature, 100°C or more, more preferably 200°C.
The above is used. The maximum temperature for drying is not particularly limited, but in consideration of drying energy and decomposability of the polymer, it is preferably 500° C. or lower.

In producing the film by the method of the present invention, the above steps may be carried out batchwise or continuously, and it is also a preferred embodiment to produce the film while running it continuously throughout the entire process. be. Further, an oil agent, an identification dye, etc. may be added to the film in any step.

(Example) Examples and reference examples (manufacturing examples of PPTA) are shown below, but these reference examples and examples explain the present invention, and do not limit the present invention. In the examples, parts by weight or weight % are shown unless otherwise specified. The logarithmic viscosity ηinh was measured by a conventional method at 30° C. by melting 0.2 g of polymer in 98% sulfuric acid]-00 m (!).

The viscosity of the dope was determined using a B-type viscometer at a rotation speed of 1 rpm. The thickness of the film is 2n in diameter.
Measured using a dial gauge with a measuring surface. Strength and elongation and modulus were determined by cutting a film sample into a 100+nXIQ rectangle using a constant-speed extension type strength and elongation measuring machine.
Initial grip length 30m, pulling speed 30n/min, load -
The elongation curve was drawn five times and calculated from this.

Light transmittance is measured as follows. A film is pasted onto the liquid cell of an ordinary photoelectric photometer (or spectrophotometer needle), visible light with a wavelength of 600 nm is selected, and its transmittance is measured.

Density values were determined at 30°C by density gradient tube method using carbon tetrachloride-toluene.

Reference Example (Manufacture of PPTA) The following PPTA was obtained by a low temperature solution polymerization method. In the polymerization apparatus shown in Japanese Patent Publication No. 53-43986, N
-70 parts of anhydrous lithium chloride in 1000 parts of methylpyrrolidone
Then, 48.6 parts of bulk phenylene diamine were dissolved. After cooling to 8°C, 91.4 parts of terephthalic acid dichloride was added at once in powder form. After a few minutes, the polymerization reaction product solidified into a cheese-like shape, so
The polymerization reaction product was discharged from the polymerization apparatus according to the method described in Japanese Patent Application No. 86, and immediately transferred to a two-screw closed Niegoo, and the polymerization reaction product was finely pulverized in the same Niigoo. Next, the finely pulverized product was transferred to a hexyl mixer, an approximately equal amount of water was added, and the mixture was further pulverized, filtered, washed several times in hot water, and dried in hot air at 110°C. Pale yellow PPTA with ηinh of 6.5
95 parts of polymer were obtained. In addition, polymers with different ηtnh have different ratios of N-methylpyrrolidone and monomers (phenylenediamine and terephthalic acid dichloride),
Or/and can be easily obtained by changing the ratio between monomers.

Example 1 PPTA having an ηinh of 6.2 was dissolved in 99.6% sulfuric acid at 60°C to a polymer concentration of 14.0%. This dope exhibits optical anisotropy at 80°C and has a viscosity of 33
It was 00 poise. This dope was applied onto a glass plate at 120° C. using an applicator with a 0.1 fl step. When air containing atomized water at normal pressure obtained from saturated steam at a pressure of about 3 kg/cnlG was blown onto the applied dope, the optical It was confirmed that it became isotropic. Immediately after that, the dope was placed in water at 20°C along with the glass plate and solidified.
It was neutralized with a 5% aqueous solution of caustic soda, and then washed with water for two days and nights. This wet film was heated at 250℃ for 1
Table 1 shows the properties after drying for a fixed length of time.

Comparative Example 1 After applying the optically anisotropic dope of Example 1 to a glass plate in the same manner, if the glass plate was left in the air while keeping the temperature at 120°C, the isotropy time shown in Table 1 It was confirmed that the film became optically isotropic after the time indicated in . The temperature at that time was 28°C and the relative humidity was 58%. Thereafter, coagulation, neutralization, water washing, and drying treatments were performed in the same manner as in Example 1. The properties of this film are shown in Table 1.

Comparative Example 2 The optically anisotropic dope of Example I was similarly applied to a glass plate, and then immediately placed in a dry nitrogen oven at 120°C.
It was held for 90 seconds. Although this dope was not optically isotropic, it was coagulated, neutralized, washed with water, and dried in the same manner as in Example 1. The properties of this film are shown in Table 1.

Example 2 A test was conducted in the same manner as in Example 1 using the same dope as in Example 1 on a glass plate at 50°C. Table 1 shows the time required to achieve optical isotropy and the properties of the obtained film.

Comparative Example 3 The optically anisotropic dope of Example 1 was similarly applied to a glass plate, and then the glass plate was kept in air while maintaining its temperature. Optical isotropy was achieved after the time shown in Table 1, Isotropy time. Temperature and relative humidity are 32℃ and 76%, respectively.
was. The properties of the obtained film are shown in Table 1.

(Effects of the Invention) As shown in the examples, the present invention has good mechanical properties such as high strength and high modulus that are not found in commercially available films, and also has good mechanical properties in the MD direction and TD force direction. Aromatic polyamide films with well-balanced physical properties can be produced in a short time. Furthermore, the film obtained by the method of the present invention has not only mechanical properties but also excellent electrical insulation, heat resistance, oil resistance, pressure resistance, resistance to chemicals other than strong acids, and dense structure. For this reason,
It can be suitably used for insulating materials, magnetic tapes, flexible printed wiring boards, wire coating materials, filtration membranes, etc. for electrical equipment that rotates at high speed, and another feature of its excellent transparency makes it suitable for packaging. It is also useful for materials, plate-making materials, photographic films, etc. One of the important effects of the present invention is that a PPTA film having such excellent properties can be manufactured by an industrially extremely easy method and without the need to use a biaxial stretching machine.

Agent Patent Attorney Takeshi Kawakita Long Procedural Amendment September 27, 1985 Director General of the Patent Office Michibe Uga 1, Indication of Case 1985 Patent Office No. 178283 2, Name of Invention Polybara Phenylene Terephthalamide Process for manufacturing 3-based film, relationship with the amended case Patent applicant address 1-2-6 Dojimahama, Kita-ku, Osaka-shi, Osaka Name (003) Asahi Kasei Industries Co., Ltd. Representative Masaomi Seko 4, Agent 103 Address: 11-8 Nihonbashi Kayabacho, Chuo-ku, Tokyo (
Benimoe Building) Telephone 03 (639”) 5592
Number Name (7658) Patent Attorney Takeshi Kawakita 5
, Date of amendment order Voluntary 6, Subject of amendment Detailed explanation of the invention in the specification.

7. Contents of the amendment (1) In the specification box, page 6, line 5, "high strength" is changed to "r high elongation."

(2) "High strength" on the bottom line of page 1 of the specification has been changed to "high strength and elongation."

(3) In the lower line of page 1 of the specification, the phrase "having a film" has been changed to "having a film with excellent flatness."

(4) "Optical isotropy without loss" on page 16, line 5 of the specification: "Excellent transparency without loss,"
Changed to isotropic J, which has greater strength and elongation.

(5) Change “to prevent tension” from line 2 on page 16 of the specification to “
To prevent this, or to make the film flat, the tension is
Changed to

(6) Add the following between the third and second lines from the bottom of page 16 of the specification.

The number of voids is determined as follows: A piece of film of suitable size is observed under a conventional optical microscope using transmitted light in at least five different fields of view at magnifications ranging from 100x to 400x. , the number of voids with a major axis of 30μ or more is counted and calculated per 1 mrr of film surface.

A known method can be used to measure the crystal orientation angle.
For example, the following method is used. The incidence of X-rays can be divided into two cases: a case where the X-ray is incident at right angles to the film surface (hereinafter referred to as the TV direction) and a case where the X-ray is incident parallel to the surface (hereinafter referred to as the SV force direction). The film of the present invention
2θζ, which is the reflection of the (200) plane by X-rays from the direction
It has a large diffraction peak at 23°, and is further reflected at 2θ-18° from the (010) plane due to incidence from the s V direction.
A large diffraction peak appears on the equator line. A diffraction intensity curve is obtained by placing the counter at a predetermined 20 angle and rotating the film 180''.

In addition, for TV, the maximum intensity is centered around 90
Rotate between °. The value of the arc length in degrees in the diffraction photograph corresponding to the point where the highest intensity of this curve is half the intensity of the baseline drawn between the lowest intensity points (
In other words, the angle relative to the 50% point of the baseline with the highest intensity is measured, and this is taken as the crystal orientation angle of the sample. During the measurement, the diffraction intensity can be measured by stacking several films if necessary. Striped patterns, if present, can be seen with a normal optical microscope, but when observed under a polarized light microscope at crossed Nicols or close to crossed Nicols, they become more clearly visible as stripes with various colors. , observed. j(7) Table 1 on page 20 of the specification box has been amended as follows.

Below margin

Claims (1)

[Claims] (1) A polyparaphenylene terephthalamide-based polymer having a logarithmic viscosity ηinh of 2.5 or more and at least one solvent selected from the group consisting of sulfuric acid, chlorosulfuric acid, and fluorosulfuric acid at a concentration of 98% by weight or more. A dope containing optical anisotropy at temperatures around room temperature or higher is formed into a film on a support surface while maintaining optical anisotropy, and the dope is heated to 45° C. or higher with saturated steam or supersaturated steam. Or polyparaphenylene terephthalamide, which is characterized in that the optically anisotropic dope is substantially converted into an optically isotropic dope by absorbing moisture in a gas containing atomized water, and then solidified and then washed. A method for producing a film based on the method.