KR930006241B1 - Forming method for aromatic polyamide film - Google Patents

Abstract

The aromatic polyamide film is produced by (1) discharging a liquid crystal prepolymer through the device for molecular orientation and simultaneously orienting the prepolymer by giving a high shear force of above 500 sec-1, (2) ejecting the oriented product into the polymerization accelerating and precipitating agent solvent and completely polymerizing in the form of film, and (3) winding the film at a drawing rate of 1-4. The lip gap of film die is 0.01-5 mm. The film has a high strength and abrasion resistance, and is useful for FRP in automobile or airplane industry.

Description

Method for producing aromatic polyamide film

1 is a schematic view of the manufacturing process of the film according to the present invention.

* Explanation of symbols for main parts of the drawings

1: feed tank 2: polymerization accelerator

3: reservoir 4: supply pump

5: film die 6,6 ': roller

7: winder

The present invention relates to a method for producing an aromatic polyamide film. More particularly, the liquid crystal prepolymer of a wholly aromatic polyamide prepared in advance is completely polymerized by contacting with a polymerization accelerator precipitant after being ejected at the same time as the molecular alignment by molecular alignment means. The present invention relates to a method for producing a high strength and high wear resistant aromatic polyamide film having a single structure without a crystal defect layer.

Recently, the development of new materials that can be used very lightly, strong, and robust in the aircraft and aerospace industries, etc. has been requested, and high strength and high elasticity inorganic fibers are developed and used using ceramics, graphite, or fluorine. They were very expensive and difficult to handle, so they were not widely applied.

As a new material, aromatic polyamide film not only has high wear resistance, high strength and high elasticity, but also has a property of blending and insolubility, and is widely used as a raw material for reinforcing plastics in automobiles and aerospace industries. It is possible to apply to the field requiring characteristics.

Due to such usefulness, various methods of manufacturing an aromatic polyamide film have been researched and developed, and the related arts are as follows.

U.S. Patent Nos. 3,869,429 and 3,869,430 describe techniques for the polymerization and spinning of aromatic polyamide films, i.e. after dissolving inorganic salts and aromatic diamines in amide solvents, aromatic dieside chlorides are After polymerization, the crumb form, for example, acid crumb-type polymer was washed with water to separate the polymerization solvent and the inorganic salt and dried, and then 20% by weight in sulfuric acid crab solvent such as chlorosulfuric acid or fluorosulfuric acid or more than 98%. It melts to a degree to make a liquid crystal dope (dope), and the doping is a technique for producing an aromatic polyamide film through spinning, neutralization, water washing, drying and mechanical treatment through water. However, when using such a method, the polymerization process, washing process, preparation of dope using sulfuric acid, spinning and mechanical treatment must be performed, and thus, the manufacturing process is complicated. Therefore, manufacturing cost increases. Due to its use, the manufacturing apparatus may be corroded, and the risk may not be accompanied, the physical properties of the film may be degraded due to the polymer reaction in the dope, and the treatment of calcium sulfate (CaSO ₄ ) produced as a by-product is difficult. Due to the residual sulfuric acid in the film, the color of the film was not changed from the yellow to the black yellow over time.

By the way, when manufacturing an aromatic polyamide film through such a conventional method, the aromatic polyamide film due to its weak compressive strength due to the kink-band phenomenon generated by the diffusion of solvent in the film manufacturing process It shows much lower strength than the original theoretical strength, and the crystal defect layer is also formed on the film itself, which has a disadvantage of significantly inferior chemical resistance.

In addition, in the case of using the conventional spinning method as described above, the polymerization degree could not be increased because water and solvent diluent are used as the coagulation bath during spinning, and due to the characteristics of heat and dope residence time generated during spinning, There was also a problem that the degree of polymerization of the polymer is reduced.

Accordingly, the present inventors have been made to solve the conventional problems, and to prepare an aromatic polyamide film having a high strength and a high degree of orientation by separating the polymerization process and molecular orientation process for the prepolymer of the aromatic polyamide prepared in advance The purpose is to provide a way to.

In addition, another object of the present invention is easy to process management and low manufacturing cost, the intrinsic viscosity of 4.0 or more can be directly polymerized and produced directly at the same time, the distribution of molecular chain is equal, without the appearance of crystal defect layer and kinkband It is an object to provide an aromatic polyamide film with no color change.

Hereinafter, the present invention will be described in detail.

In the present invention, in preparing an aromatic polyamide film by contacting an aromatic polyamide prepolymer in a liquid crystal state with a polymerization accelerator, the liquid crystal state is supplied to a film die by means of a supply pump, followed by a discharge of 0.01 to 5 mm. Aromatic polyamide film, which is discharged through a gap (lip gap), is oriented by the total residual force at the time of discharging, is blown into a polymerization accelerator, and completely polymerized in a film form, and then wound at an elongation of 1 to 4. It is a manufacturing method of.

Hereinafter, the present invention will be described in more detail.

In the present invention, the aromatic polyamide liquid crystal prepolymer is polymerized by adding an aromatic diamine and an aromatic dieside chloride to a solution in which an inorganic salt is dissolved in an amide solvent or an amide solvent containing a small amount of tertiary amine. It refers to the polymer solution formed at the point before gelation after stir opalesence showing the opalescent color and the secret color, and the liquid crystal polymer solution has the intrinsic viscosity of 1.0 to 4.0. It is an optically anisotropic liquid crystalline prepolymer having repeating units and having the properties of a copolymer or a homopolymer.

In the structural formula (I), (II), R ₁ , R ₂ and R ₃ are

R ₁ , R ₂ may be the same or different and R ₁ , R ₂ are generally present in equimolar amounts.

For example, in the polymerization method of the above-described preliminary solution of the intermediate (polymerization media or instir polymer Dope), an aromatic diamine in an amide solvent in which an inorganic salt (metal halide salt) is dissolved or an amide solvent in which a small amount of tertiary amine is contained. It is obtained by dissolving and then polymerization by a solution polymerization method which is cooled to low temperature under a nitrogen stream, and then added at an aromatic dieside chloride and reacted at a low temperature of 40 ° C. or less, wherein the monomer and the solvent contain a minimum amount of impurities, Only when the polymerization reaction proceeds quantitatively, it is possible to obtain a liquid crystal prepolymer having a suitable molecular weight that can be supplied to the manufacturing process of the final polymer.

On the other hand, as the polymerization solvent used in the present invention, amide-based and urea-based organic solvents may be used alone, or a mixture thereof may be used. If necessary, amide- and urea-based compounds containing a small amount of tertiary amine may be used. An organic solvent can be used. As the amide solvent, for example, N-methyl-2-pyrrolidone (NMP), N, N'-dimethylacetamide (DMAC), hexamethylphosphoramide (HMPA), N, N'-dimethylformamide (DMF), N, N'-dimethylsulfoxide (DMSO), N, N, N ', N'-tetramethylurea (TMU) and the like are mainly used, in addition, N-methylpiperidone, N-methylcaph Rollactam, N-acetylpyrrolidine, N-ethylpyrrolidine, dimethylpropionamide, dimethylisobutylamide, and dimethyl propylurea may be used as the polymerization solvent as the uraa solvent.

And, if necessary, the tertiary amine which may be contained in the polymerization solvent is selected from, for example, pyridine, quinoline, triethylamine, t-butylamine, picoline, pyrimidine, pyrazine, quinoxaline and dimethylethylamine. It can be used, these are preferably used 0.01 to 2% by weight relative to the polymerization solvent.

If the amount of tertiary amine is less than 0.01% by weight, the effect of addition of tertiary amine is not good. On the contrary, when the amount of tertiary amine is used at 2% by weight or more, it is difficult to control the reaction rate, making process control difficult. .

On the other hand, the inorganic salt used to increase the solubility of the polymer is a metal halide salt such as lithium chloride (LiCl), calcium chloride (CaCl ₂ ), potassium chloride (KCl), potassium bromide (KBr), lithium bromide (LiBr), etc. Although these may be mainly used, these are preferably used by adding 0.5 to 15% by weight (weight of salt / amide solvent volume) based on the polymerization solvent.

A halogenated metal salt is added to such an amide-based solvent or an amide-based solvent containing a small amount of tertiary amine, and then aromatic diamine (p-phenylenediamine) and aromatic dieside chloride (terephthaloyl chloride) which are monomers at low temperature. When the reaction is performed to some extent by adding and stirring, the polymer in the solution is obtained as the poly (p-phenylene terephthalamide) of the following structural formula (III) to the optically anisotropic liquid crystal prepolymer which is in the state before the reaction is completed.

At this time, the liquid crystal prepolymer dope is distinguished from the dope dissolved in a solvent by separating the polymer after polymerization is completed as in the prior art.

The liquid crystal prepolymer solution may be used in an amount of 4 to 20% by weight, more preferably 5 to 15% by weight. If the content rate is less than 4% by weight, there is a disadvantage in that the intrinsic viscosity of the final polymer is sharply lowered, a loss occurs in cost, and if the content rate is more than 20% by weight, it is not suitable for use as a liquid crystal dope. There are drawbacks to this.

In addition, the intrinsic viscosity of the liquid crystal prepolymer is preferably 1.0 to 4.0. In terms of process management, it is more preferable that it is 1.5-3.5. If the intrinsic viscosity of the polymer is high in content, it is difficult to use it as a liquid crystal dope.

Referring to the manufacturing process of the present invention based on the illustrated drawings are as follows.

1 is a process diagram showing an embodiment of the present invention, that is, the non-polymer supply tank (1) and the polymerization promoting precipitate (2) in a liquid crystal having a size that can accommodate the liquid crystal prepolymer obtained as described above at the liquid crystal level (2). The molecular alignment means is supplied to the film addy 5 through the feed pump 4 with the liquid crystal prepolymer contained in the feed tank 1 in a state where the reservoirs 3) are separately installed and installed. After discharging through the discharge interval of 0.01 to 5 mm of the die 5, the orientation is sufficiently discharged into the polymerization promoter precipitate of the bath 3 and moved in the direction of the arrow using the rollers 6 and 6 ′. The polymerization is carried out while being immersed in the polymerization accelerator precipitate (2). Then, the film-type polymer thus prepared is wound up with the winder 7 with the elongation ratio of 1 to 4, which is the ratio in the film when leaving the polymerization accelerator to the ejection rate in the film die 5, and washed and dried. An aromatic polyamide film according to the present invention is to be produced.

On the other hand, in the above process, the polymerization promoter has the advantage of significantly improving the degree of polymerization of the liquid crystal prepolymer, thereby completing the polymerization and forming the amide bond and the hydrogen bond of the polymer, thereby improving the growth of molecular orientation. Tertiary amines are generally mentioned as polymerization precipitants used in the embodiment of the present invention. For example, pyridine, triethylamine, t-butylamine, picoline, quinoline, pyrimidine, pyrazine, quinoxaline, It can be used by selecting among the pyridine, but among them, pyridine is the most suitable polymerization accelerator, it can be said to be effective in obtaining high intrinsic viscosity and orientation.

In addition, the use of such a polymerization promoter precipitate may be used as the above tertiary amines alone, but is partially selected from amide solvents such as NMP, DMAC, HMPA, TMU, or mixed with 10 wt% of these solvents. In this case, the amount of tertiary amine in the mixed solution of tertiary amines, amide solvents or inorganic salts is determined by hydrochloric acid (HCl) produced by diamine and dieside chloride reaction during polymerization. It is preferable that the equivalent of more than, and the amount of water contained in the polymerization accelerator is preferably set to about 5,000ppm or less.

The liquid crystal prepolymer supplied to the film die 5 by the fixed-quantity supply pump 4 is discharged through a discharge interval (lip gap) of 0.01 to 5 mm, and is oriented with the shear force below. If the gap is narrower, the polymerization accelerator penetrates relatively easily to the inside of the oriented polymer, so that the intrinsic viscosity (η _lnh or IV) and molecular orientation can be easily increased. In addition, the longer the contact time of the polymer oriented polymer and the polymerization accelerator precipitated, the better it is, but the disadvantages of time appear uneconomical, so it is better to adjust the contact time to 0.1 to 1,000 seconds.

The film produced by the above method is improved in overall physical properties by heat treatment, that is, when the film is heat treated under tension, the modulus of increase and elongation can be seen, wherein the modulus is increased by 30 to 80% & about The elongation is reduced by 30 to 40%.

The present invention has a molecular chain structure that is fully expanded by the molecular orientation polymerization method, the final microstructure of the formed film, the distribution of the chain ends are formed evenly in the film axis direction and the bonding portion in the film axis direction There is no crystal defect layer according to the wrinkled sheet structure, the intrinsic viscosity is 4.0 or more, and the strength has a single structure of 15g / d or less.

On the other hand, evaluation of the physical properties of the film produced according to the present invention can be easily seen from the relation of the intrinsic viscosity (I.V.) shown in the following.

Where C is the concentration of the polymer solution (0.5 g of polymer or film in 100 ml of solvent) and η _rel is the relative viscosity, which is the ratio of the flow time between the solution and the solvent measured with a capillary viscometer at a temperature of 30 ° C. The solvent is usually concentrated sulfuric acid (H ₂ SO ₄ ; 95 to 98%) unless otherwise defined.

As described above, according to the present invention, the aromatic polyamide film as a new material not only has high wear resistance, high strength and high elasticity, but also has insoluble and insoluble properties. It is used, and also excellent in the properties of the film itself, there is an effect that can be used in various fields that require high strength, high elasticity, high wear resistance, insoluble, insoluble properties that are not applicable to the existing polyester film.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1

Substituting a 5 L volume four-necked flask with N ₂ and removing water as much as possible, 1.2 ml of NMP was added to the flask, and 27.0 g of CaCl ₂ was added to the flask at a temperature of 100 ° C. to completely dissolve it. , 4.5 g of PPD2 were sufficiently dissolved in the above solution, and a cooling water bath was installed to cool the mixture, and 45.95 g of TPC was added thereto while stirring to lower the temperature. At this time, the stirring speed (rpm) was 3,000 times / minute while reacting for 15 minutes to form a prepolymer solution.

The polymerization solution thus obtained was discharged using a film die having a width of 25 mm and 0.2 mm, and then, the polymer solution in the discharged film state was contacted with pyridine and wound up at a speed of 20 m / min. It was then washed with water and dried to give an aromatic polyamide film. At this time, the intrinsic viscosity was 5.2 ml / g, and the measurement result of E / T / Mi was 55/22/515.

[Examples 2 to 9]

Next, using the reaction solvent and the side salt as shown in Table 1, and after the polymerization in the same manner as in Example 1 by changing the polymerization accelerator and polymerization time I.V. And E / T / Mi was measured and the results are shown in Table 1 below.

[Examples 10 to 15]

Next, after using the inorganic salt and the polymerization accelerator as shown in Table 2 and performing the same method as in Example 1 while changing the reaction solvent, I.V. And E / T / Mi was measured and the results are shown in Table 2 below.

Example 16

6.3 g of CaCl ₂ was added and dissolved in a mixed solvent of 130 mL of NMP and 20 mL of DMAC, and then 4.19 g of PPD was added to the solution and 9.19 g of TPC was added thereto while stirring to polymerize.

At this time, the temperature of the polymerization solution was allowed to react for 10 minutes while cooling with cold water not to exceed 40 ° C, and then spun into a pyridine solvent through a film die having a slot having a width of 25 mm, a gap of 0.5 mm, and an L / D of 2.0. Winding at a speed of 30m / min, washed with water and dried to prepare a film and the results were as follows.

The inherent viscosity was 4.9 ml / g and E / T / Mi was 3/22/450.

TABLE 1

TABLE 2

[Examples 17 to 22]

As shown in Table 3 below, the L / D and the elongation were changed, and all other conditions were the same as those in Example 16. And the result of measuring E / T / Mi is shown in Table 3 below.

TABLE 3

[Examples 23 to 27]

The gap is changed as shown in Table 4 below, and all other conditions are the same as those in Example 16. And the result of measuring E / T / Mi is shown in Table 4 below.

TABLE 4

Claims (2)

In producing the aromatic polyamide film by contacting the liquid crystal state aromatic polyamide prepolymer with the polymerization accelerator, the liquid crystal state is discharged through the molecular alignment means while being oriented by the shear force and into the polymerization accelerator. A method of producing an aromatic polyamide film, which is obtained by ejecting and completely polymerizing a film, followed by winding at an elongation of 1 to 4. The method for producing an aromatic polyamide film according to claim 1, wherein the molecular alignment means is a lip gap of 0.01 to 5 mm of the film die.

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