KR930006243B1 - Forming method for aromatic polyamide film - Google Patents

Abstract

The aromatic polyamide film is produced by (1) orienting a liquid crystal prepolymer by a high shear force of above 100 sec-1 before introducing the prepolymer into the polymerization accelerating and precipitating agent solvent through a rotating roller, (2) completely polymerizing the prepolymer in the solvent, (3) separating the polymer formed in the form of film, (4) heat treating, washing and drying. 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 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 tube

5: rotary roller 6: shear blade

7: Separation blade 8,10,10 ', 12,12': Induction roller

9: heat treatment tank 11: high temperature plate

13: polymerization accelerator precipitator inlet 14: polymerization accelerator precipitator outlet

The present invention relates to a method for producing an aromatic polyamide film, and more particularly, after the liquid crystal prepolymer prepared in advance is subjected to molecular alignment while applying shear force with a shear blade, polymerization is performed using a rotating means. The present invention relates to a method for producing an aromatic polyamide film having high orientation and high crystallinity, which is completely polymerized while being in contact with an accelerating precipitant and heat treated by high heat means.

Recently, the development of a new material that can be used very lightly, strong, and robust in the aircraft and aerospace industry, etc., has been requested, using high-strength, high-elastic inorganic fibers using ceramics, graphite or fluorine, etc. The materials are very expensive and difficult to handle, so they have not been widely applied.

As a new material, aromatic polyamide film not only has high abrasion resistance, high strength and high elasticity, but also has characteristics of incompatibility 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 have introduced techniques for the polymerization and spinning of aromatic polyamide films, i.e., this technique dissolves an inorganic salt and an aromatic diamine in an amide solvent, and then an aromatic dieside chloride. Was polymerized at low temperature to wash the polymer in crumb form, for example, acid crumb, with water to separate the polymerization solvent and the inorganic salt and dried, and then to 98% sulfuric acid or sulfuric acid solvent such as chlorosulfuric acid or fluorosulfuric acid. It is a technology for producing aromatic polyamide film by melting about 20% by weight to form a liquid crystal dope (dope), and the dope through spinning, neutralization, washing with water, drying and mechanical treatment. However, when such a method is used, the process is complicated because the polymerization process, washing process, preparation of dope using sulfuric acid, spinning and mechanical treatment must be performed, and thus manufacturing cost increases. Potassium hydroxide may be corroded by the sodium hydroxide used during the use and neutralization process, and it is not good to follow the risk, and the physical properties of the film may be degraded by the polymer reaction in the dope, and potassium sulfate (CaSO ₄₎ produced as a by-product. ), And the color of the film changed from pale yellow to black yellow over time due to residual sulfuric acid in the film.

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

In addition, in the case of using the conventional spinning method described above, water and solvent diluent are used as the coagulation bath during spinning, and thus the degree of polymerization cannot be increased, and heat and dope residence time generated during spinning can be expected. There was also a problem that the degree of polymerization of the polymer is lowered.

Accordingly, the inventors of the present invention have been made to solve the problems of the prior art, and the polymerization process and molecular alignment process of the prepolymer of the aromatic polyamide prepared in advance at about the same time to produce a film to improve the subsequent heat treatment step and high crystallinity and It is an object of the present invention to provide a method for producing an aromatic polyamide film having a high degree of orientation.

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, immediately before the liquid crystal state is formed into a film on a rotary roller and introduced into the polymerization accelerator. After aligning with high shear force of 1000 sec ^-1 or more through a shear blade, the rotary roller was rotated at a speed of 6 to 48 m per minute in a polymerization accelerator to completely polymerize the oriented liquid crystal prepolymer, and then It is a method for producing an aromatic polyamide film by separating a polymer and heat-treating it at a temperature of 100 to 300 ° C. for 1 to 5 seconds while contacting and moving it in a flat state on a high heat means, followed by washing and drying.

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

In the present invention, the aromatic polyamide liquid crystal prepolymer is stir opalesence which shows alum and white color during the polymerization reaction by adding aromatic diamine and aromatic dieside chloride to a solution in which an inorganic salt is dissolved in an amide solvent. This refers to a polymer solution formed at the point before gelation, and the liquid crystal polymer solution is an optically anisotropic liquid crystal prepolymer having a characteristic of a copolymer or homopolymer having an intrinsic viscosity of 1.5 to 3.0.

For example, the liquid crystal prepolymer solution (polymerization media or in stir polymer dope) dissolves an aromatic diamine in an amide solvent in which an inorganic salt (metal halide salt) is dissolved, and then cools it to low temperature under a nitrogen stream, and aromatic dieside. It is obtained by polymerization by a solution polymerization method in which chloride is added and reacted at a low temperature of 40 ° C. or lower. At this time, the monomer and the solvent contain a minimum amount of impurities and must be quantitatively polymerized to be supplied to the final polymer production process. A liquid crystal prepolymer having an appropriate molecular weight can be obtained.

On the other hand, the polymerization accelerator for the catalyst used in the present invention can be mainly used an amide solvent, for example, N-methyl-2-pyrrolidone (NMP), N, N'-dimethyl as the amide solvent Acetamide (DMAC), hexamethylphosphoramide (HMPA), N, N'-dimethylformamide (DMF), N, N'-dimethylsulfoxide (DMSO), and the like. In addition, N-methylpiperidone , N-methylcaprolactam, N-acetylpyrrolidine, N-ethylpyrrolidine, dimethylpropionamide and dimethylisobutylamide can be used as the polymerization solvent.

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

After the metal halide is added to the amide solvent as described above, the reaction is performed by adding and stirring an aromatic diamine (p-phenylenediamine) and an aromatic dieside collide (terephthaloyl chloride) as monomers at a low temperature. The polymer in the optically anisotropic liquid crystalline prepolymer solution, which is in this pre-completed state, is obtained.

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, so that a loss occurs in cost, and if the content is more than 20% by weight, it is not suitable for use as a liquid crystal dope. There is a disadvantage.

In addition, the intrinsic viscosity of the liquid crystal prepolymer is preferably 1.5 to 3.0 in terms of process control. If the intrinsic viscosity and content rate of the polymer are high, it is difficult to use the liquid crystal dope.

Referring to the process for producing a film according to the present invention using such a liquid crystal prepolymer based on the illustrated drawings are as follows.

1 is a process diagram showing an embodiment of the present invention, that is, the liquid crystal prepolymer supply tank (1) and polymerization accelerator precipitant (2) having a size that can accommodate the liquid crystal prepolymer obtained as described above at a predetermined level. The liquid crystal prepolymer contained in the supply tank 1 is supplied to the polymerization accelerator precipitating medium 2 through the supply tube 4 in a state where the contained storage tanks 3 are separated and installed, respectively. It is supplied in the form of coating on the circumferential surface of the rotary roller (5), which is a rotating means installed in a part immersed in the inside. At this time, the shear blade 6, which is a shear force imparting means installed adjacent to the upper side of the rotary roller 5, is oriented while imparting a shear force of 1000 sec ⁻¹ or more to the liquid crystal prepolymer. Then, the rotating roller 5 was rotated in the direction of the arrow to coat the film so that the oriented liquid crystal prepolymer was moved along the rotary roller 5 into the polymerization accelerator precipitant 2 at a speed of 6 to 48 m / min. Allow polymerization to occur. Subsequently, the film-form polymer prepared by the completion of polymerization is separated on the rotary roller 5 by the separating blade 7, and the induction means provided above the separating blade 7 is the first induction roller. (8) is used to guide the inside of the high heat treatment tank (9). Thus, the film-like polymer guided into the high heat treatment tank 9 passes between the second induction rollers 10 and 10 ′ and the upper surface of the high heat plate 11 having a temperature of 100 to 300 ° C. which is a high heat means 1 After the heat treatment while in contact for 5 seconds to come out of the high heat treatment tank (9) through the third induction roller (12, 12 ') is wound up with a winder (not shown), washed and dried An aromatic polyamide film according to the present invention is to be produced.

In the drawing, reference numeral 13 denotes an inlet through which the polymerization accelerator precipitate is introduced, and reference numeral 14 denotes an outlet through which the polymerization accelerator precipitate flows out.

On the other hand, in the above process, the liquid crystal prepolymer is quantitatively rotated on the circumferential surface of the rotary roller 5 in a state in which a part of the liquid crystal precipitant is precipitated in the polymerization promoter precipitator 2 by a gear pump (not shown in the drawing). In this case, the prepolymer receives the shear force of 1000 sec ⁻¹ or more by the shear knife 6, which is a shearing force applying means, and is oriented while being coated onto the film on the circumferential surface of the rotary roller 5. At this time, the distance between the shear talum 6 and the circumferential surface of the rotary roller 5 is preferably 0.1 to 0.2 mm, which is preferable to improve the physical properties of the final product. In addition, the shear stress received by the liquid crystal prepolymer solution should be more than 1000sec ^{-1 to} further improve the physical properties of the final product.

In this process, the liquid crystal prepolymer coated and oriented in a film shape is continuously immersed into the polymerization accelerator precipitant 2 by the rotation of the rotary roller 5.

On the other hand, the polymerization accelerator is significantly improved the degree of polymerization of the liquid crystal prepolymer to complete the polymerization and at the same time to form an amide bond and hydrogen bond in the polymer has the advantage of improving the growth of molecular orientation bar, for example used in the embodiment of the present invention Tertiary amines may be generally used as the polymerization precipitating agent, for example, pyridine, triethylamine, t-butylamine, picoline, quinoline, pyrimidine, pyrazine, quinoxaline, and acpyridine. Among them, however, pyridine may be said to be effective in obtaining high intrinsic viscosity and orientation as the most suitable polymerization accelerator.

The film polymer according to the present invention manufactured in this process passes through the high temperature plate 11 maintained at a high temperature by the induction rollers 8, 10 and 10 ′ in contact with each other. At this time, the temperature of the high temperature plate 11 is maintained at 100 to 300 ℃, the contact time of the film-like polymer and the top surface of the high temperature plate 11 is preferably about 1 to 5 seconds. If the contact time exceeds the above range, the effect of the present invention cannot be obtained.

In the embodiment according to the present invention, the first and second induction rollers 10, 10 ′, 12, 12 ′ may efficiently heat-treat the film according to the present invention, that is, the film polymer coming into the high heat treatment tank 9. It also plays the role of keeping it flat on both sides.

The film produced by the above method is improved in the overall physical properties by the heat treatment as described above, that is, when the film is heat treated under tension can be seen the effect of increasing the modulus and elongation. At this time, the modulus is increased by about 30 to 80%, and the elongation is reduced by about 30 to 40%.

When the film produced by the method according to the present invention is washed with water and dried by a conventional method, the orientation angle is 20 ° or less, and the crystallinity is 60% or more.

In the present invention, the liquid crystal prepolymer solution formed in the polyamide synthesis process is obtained by rotating rollers and shear blades to obtain a film shape with a certain thickness and orientation, and at the same time, the molecular weight is rapidly increased by the polymerization accelerator and high intrinsic viscosity. The polyamide film is produced, and in the subsequent process, it is possible to produce a film of high orientation and high crystallinity with respect to the heat treatment effect using a high temperature heat treatment means, and the thickness of the film can be easily controlled by the gap between the shearing force applying means and the rotating roller. It is easy to operate because the shear stress can be changed by the rotational speed of the rotary roller. In addition, the final product of the film produced by the conventional method The physical properties are excellent effects in comparison.

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

Example 1

A 4 L flask with a volume of 5 L was sufficiently substituted with N ₂ and water was removed as much as possible. Then, 500 ml of NMP was added to the flask, and CaCl ₂ and 25.0 g were added to the flask at a temperature of 100 ° C. to completely dissolve it. Next, 15.27 g of PPD was sufficiently dissolved in the solution, a cooling water bath was installed and cooled, and 29,33 g of TPC was added while stirring to lower the temperature. At this time, the stirring speed (rpm) was reacted for 10 minutes while making 3,000 times / minute to prepare a prepolymer solution having an inherent viscosity of 2.5.

The solution thus obtained was fed to a rotary roller at a speed of 12 m / min, and was passed between a shear blade having a spacing of 0.1 mm and a rotary roller to connect the polymer of the film state obtained with a shear force of 2000 sec ^-1 with pyridine. Subsequently, the resultant was passed through a high temperature plate maintained at 300 ° C. for 3 seconds, washed with water, and dried to obtain an aromatic polyamide film. At this time, the intrinsic viscosity was 5.1 ml / g, the orientation angle was 18 degrees, and the crystallinity was 65%.

[Examples 2 to 5]

The liquid crystal prepolymer solution prepared by the same method as in Example 1 was continuously supplied to a rotating roller using a gear pump, and in this embodiment, the interval between the rotating roller and the shear blade and the rotational speed of the rotating roller were measured. The physical properties of the final product were compared by changing the shear force. At this time, the temperature of the high temperature plate was maintained at 300 ℃, the contact time 2 seconds, the results are shown in Table 1 below.

TABLE 1

[Examples 6 to 9]

Liquid crystal prepolymerization solution prepared by the same method as in Example 1 was continuously supplied to a rotating roller using a gear pump. The same conditions as in Example 1 were tested. At this time, the temperature of the high temperature plate was tested to 100 ℃, 300 ℃, the contact time of 1 second, 3 seconds, 5 seconds, the results are shown in Table 2.

TABLE 2

[Comparative Examples 1 to 4]

In this embodiment, when the spacing and shear force between the rotating roller and the shear blade is out of the scope of the present invention was tested by the same method as in Example 1, the distance between the roller and the shear blade and The changes in shear stress and the results are shown in Table 3 below.

TABLE 3

Comparative Example 5

In this embodiment, when the temperature of the high temperature plate is out of the scope of the present invention was tested in the same manner as in Example 1 to observe the physical properties of the final product, the contact time for 3 seconds to maintain the temperature of the high temperature plate at 50 ℃ Was given. The resulting polyamide film had an intrinsic viscosity (I.V) of 5.0, an orientation angle of 25 °, and a crystallinity of 45%.

Comparative Example 6

In this example, when the contact time between the polyamide film and the high temperature plate is outside the scope of the present invention, the same test as in Example 1 was carried out to observe the physical properties of the final product. It was 0.2 second. The resulting polyamide film had characteristics of inherent viscosity (I.V) 5.2, orientation angle 21 ° and crystallinity 42%.

Claims (5)

Hayeoseo contacting an aromatic polyamide pre-polymer of liquid crystal state and polymerizing promote precipitation agent was heat-treated at a shear blade on a method for the production of aromatic polyamide film, through the rotation of the prepolymer in a liquid crystal state rollers put into promote polymerization precipitant and just before 100sec ^- after orientation, giving at ^least one high shear force, out to complete polymerization was then remove the polymer on the resulting film per minute 6 to a liquid crystal prepolymer to rotate at a speed of 48m the rotating roller in a polymerization promotion precipitant can high heat it A method for producing an aromatic polyamide film obtained by heat treatment while contacting and moving in a flat state on a single phase, followed by washing and drying. The method of claim 1, wherein the liquid crystal prepolymer is coated on the surface of the rotating roller which is led into the polymerization accelerator. The method of manufacturing an aromatic polyamide film according to claim 1, wherein the liquid crystal prepolymer is subjected to a shear force while passing between the rotary roller and the shear blade, which are installed to maintain an interval of 0.1 to 0.2 mm. The method for producing an aromatic polyamide film according to claim 1, wherein the high heat means is maintained at a temperature of 100 to 300 deg. The method for producing an aromatic polyamide film according to claim 1, wherein the polymer on the film is brought into contact with the high heat means for 1 to 5 seconds.

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