KR920010644B1 - Process for aromatic polyamide film - Google Patents

Abstract

The aromatic polyamide film having at least 4.0 ml/g intrinsic viscosity, at least 190 kgf/mm2 tensile strength and at least 6300 kgf/mm2 early elasticity coefficient is produced by (a) dissolving an inorganic salt in an amide solvent contg. 0-2.0 wt.% tertiary amine (b) polymerizing it with an aromatic diamine and an aromatic diacidchloride to obtain a prepolymer having 1.0-4.0 intrinsic viscosity, (c) ejecting the prepolymer to obtain a film, (d) contacting it with a molecular polymn.-promoting solvent, and (e) washing and drying it. The organic salt is CaCl2, LiCl or LiBr.

Description

Method for producing aromatic polyamide film

The present invention relates to a method for producing an aromatic polyamide film, and more particularly, to polymerize the liquid crystal prepolymer discharged in the form of a film while passing it through a vapor-phase polymerization promoting medium maintained at a constant temperature to achieve high polymerization and initial elastic modulus. It relates to a method for producing an aromatic polyamide film having.

Conventional poly-P-phenylene terephthalamide (PPTA) films are first polymerized with PPTA polymer, washed with water and dried, and then dissolved in the sulfuric acid or polyamide solvent in the spinning process to prepare a spinning solution. Although it has been used to produce fibers or films by discharging, this method has separated the polymerization and spinning processes, which not only steamed equipment investment and labor costs, but also caused the danger of using concentrated sulfuric acid.

In addition, Japanese Patent Application Nos. 55-11763 and 55-11764 introduce techniques for improving physical properties by washing and stretching coagulated yarns obtained after spinning aromatic polyamide fibers, and drying and heat-treating them at temperatures above 300 ° C. However, this technique was only an inefficient method in which heat treatment effects immediately after spinning were not expected due to heat treatment after cleaning and stretching.

Therefore, in the present invention, instead of performing heat treatment through washing and drying after manufacturing the film as in the prior art, it is an object to prepare an aromatic polyamide film having heat treatment at the same time as well as more excellent elastic melting.

Hereinafter, the present invention will be described in detail.

The present invention dissolves an inorganic salt in an amide solvent or an amide solvent containing a small amount of tertiary amine, and then polymerizes the aromatic diamine and the aromatic diecyl chloride in equimolar amounts to provide optical anisotropy of 1.0 to 4.0. After preparing a liquid crystal prepolymer of the present invention, it is ejected in the form of a film, polymerized while being in contact with a molecular polymerized solvent, washed with water and dried to prepare an aromatic polyamide film, wherein the liquid crystal prepolymer is 100 to 4.0 optically anisotropic liquid crystal After preparing the prepolymer, it is ejected in the form of a film, polymerized while contacting with a molecular polymerization accelerator, and then washed and dried to prepare an aromatic polyamide film. The liquid prepolymer is heated to a temperature of 100 to 300 ° C. It was discharged into the type of molecular polymerization promoting solvent and contacted for 1 to 7 seconds, followed by washing with water. And in that characterized in that the drying to an intrinsic viscosity of 4.0ml / g or more that is, a tensile strength of 190kg _f / mm ² or more, an initial modulus of elasticity be 6300kg _f / mm ² or more in the method for producing an aromatic polyamide film.

Such a present invention will be described in more detail as follows.

The present invention dissolves an inorganic salt in an amide solvent or an amide solvent containing a small amount of tertiary amine, and induces low temperature polymerization of an equimolar amount of aromatic diamine and an aromatic dieside chloride. An optically anisotropic liquid crystal prepolymer is prepared first. Then, when the prepolymer solution adjusted to the optically anisotropic liquid crystal state is discharged through the film die before the solidification into the vapor polymerization molecular solvent, the polymerization solvent in the prepolymer is formed by the high temperature molecular polymerization promoter. diffusing volatile as being the degree of polymerization and the initial elastic modulus ascend and at the same time, continuous take-up in an instant are arranged in a state that the molecular chains fully oriented tensile strength 190kg _f / mm ² or more, an initial modulus of 6300kg _f / mm ² or more, the orientation angle is 20 ° Hereinafter, an excellent film having an intrinsic viscosity of 4.0 ml / g or more is produced.

Meanwhile, when preparing the prepolymer, an inorganic salt is added to the amide solvent, and dissolved by adding 3 to 15% by weight with respect to the polymerization solvent. The tertiary amine is included as 0 to 2% by weight, and the polymer content of the polymerization solvent is It is preferable to adjust to 5 to 20% by weight. In addition, the intrinsic viscosity of the prepolymer is preferably 1.0 to 4.0, more preferably 1.5 to 3.5. Here, if the intrinsic viscosity of the prepolymer is less than 1.0, the liquid crystallinity of the prepolymer is lowered. On the contrary, if the intrinsic viscosity of the prepolymer is less than 4.0, the process management becomes difficult. In addition, when the content of the polymer in the polymerization solvent is 5% by weight or less, the economical point is difficult, and when it is 20% by weight or more, the polymerization proceeds rapidly and the process management becomes difficult and the stability decreases.

When the liquid crystal prepolymer prepared through the above process is discharged through a film die, but is discharged into a molecular polymerization promoter maintained at 100 to 300 ° C., the polymerization solvent in the prepolymer solution is diffused and volatilized for 1 to 7 seconds, thereby increasing the degree of polymerization. Is rapidly increased and the initial modulus of elasticity is rapidly increased by high temperature molecular polymerization promoter. Subsequently, when the coil is continuously wound, the molecular chains are arranged in a completely aligned state, and a wholly aromatic polyamide film having excellent physical properties (especially initial modulus) is produced. Here, if the temperature of the molecular polymerization promoter is less than 100 ℃, the physical properties of the film is significantly reduced, if it exceeds 300 ℃ it will not be expected to further improve the physical properties, so it is not economical, as described above It is best to do it.

In addition, the molecular polymerization promoter is used in contact with the prepolymer solution to promote the reaction and to increase the degree of polymerization at the same time, mainly using a tertiary amine solvent or mixed solvent with an amide solvent or a small amount of inorganic salt Dissolved solvent is used.

As the amide solvent used in the present invention, N-methylpyrrolidone (NMP), hexamethylphosphoramide (HMPA), N, N-dimethylacetamide (DMAC), N, N-dimethylformamide, and dimethyl sulfoxide Said, NNN'-N'-tetramethylurea, etc., and inorganic salts include calcium chloride (CaCl ₂ ), lithium chloride (LiCl), lithium bromide (LiBr) and tertiary amine solvents pyridine, quinoline, pyrazine , Triethylamine, pyrroline, acriridine, quinosalin and the like are used.

On the other hand, the physical property (intrinsic viscosity) of the film produced according to the present invention can be easily seen from the following general relationship.

Where C is the concentration of polymer solution (0.5 g of film in 100 ml of solvent), ηGrel is the relative viscosity, the ratio of flow time between solution and solvent measured by capillary viscometer at temperature of 30 ° C, solvent is limited Unconcentrated sulfuric acid (95 to 98% H ₂ SO ₄ ) unless otherwise.

In the film manufacturing process according to the present invention, it is possible to manufacture the film directly during the polymerization process without the need to separate the polymerization process and the film production process as conventionally performed, but it is common to perform heat treatment after washing with water and drying after film production. It is advantageous in terms of physical properties because it can achieve the effect of rapidly increasing the initial physical properties, especially the initial modulus, by heat treatment at the same time as the film production.The solvent condensed during the polymerization process can be removed without a separate recovery device (when it is carried out according to the conventional method, The solvent must be recovered from the mixture of the solvent and water obtained after washing with water before the heat treatment process.

The present invention will be described in detail with reference to Examples.

EXAMPLE

Example 1

A 4 L flask with a volume of 5 L was sufficiently replaced with N ₂ , and water was removed as much as possible. Then, 1,200 ml of NMP was added to the flask, and 47.0 g of CaCl ₂ was added to the flask at a temperature of 100 ° C. and completely dissolved. Next, 24.5 g of PPD is sufficiently dissolved in the solution, and a cooling water bath is installed to cool the mixture, while 45.95 g of TPC is added thereto and stirred well. At this time, the stirring speed was 2,000 times / minute while reacting for 10 minutes to form a prepolymer solution. The polymerization solution thus obtained is jetted through a film die having a gap width of 0.5 mm and a width of 25 mm. The prepolymer in the form of a film ejected through the die was wound up at a rate of 20 m / min while passing through a pyridine vapor maintained at 200 ° C., washed with water and dried to obtain 58.4 g of polyamide film. At this time, the intrinsic viscosity was 5.3ml / g, the tensile strength was 270kg _f / mm ² , the initial modulus was 7,500kg _f / mm ² .

EXAMPLES 2-5

Except for changing the temperature of the molecular polymerization promoter was carried out in the same manner as in Example 1 and the results are shown in Table 1 below.

[Examples 6-19]

Except for changing the reaction solvent, the inorganic salt and the molecular polymerization promoting solvent was carried out in the same manner as in Example 1 and the results are shown in Table 1 below.

[Comparative Examples 1 and 2]

Except for carrying out the temperature of the molecular polymerization promoter outside the scope of the present invention it was the same as in Example 1 and the results are shown in Table 2.

TABLE 1

TABLE 2

Claims (3)

After dissolving an inorganic salt in a amide-based solvent containing 0 to 2.0% by weight of a tertiary amine as a dissolution accelerator, the aromatic diamine and aromatic dieside chloride are polymerized in equimolar amounts to optically anisotropy having an intrinsic viscosity of 1.0 to 4.0. After preparing a prepolymer of the present invention in the form of a film is ejected in contact with a molecular polymerization promoter and washed with water and dried to prepare an aromatic polyamide film, the liquid crystal prepolymer is heated to a temperature of 100 to 300 ℃ The intrinsic viscosity obtained by contacting for 1 to 7 seconds, washed with water and dried after being discharged into the medium for promoting the polymerization polymerization of Molecular Polymerization of Si, the tensile strength is 190kg _f / mm ² or more, the initial elastic modulus is 6300kg _f / A method for producing an aromatic polyamide film, characterized in that more than mm ² . The method of claim 1, wherein the molecular polymerization promoter is an aromatic poly, characterized in that the use of a tertiary amine solvent alone, or the addition of an inorganic salt to the mixed solution of the tertiary amine solvent and amide, or these mixed solvents. Method for producing an amide film. The amide solvent according to claim 1 or 2, wherein the amide solvent is N-methylpyrrolidone, hexamethylphosphoramide, NN-dimethylacetamide, NN-dimethylformamide, dimethyl sulfoxide, NNNN'-tetramethylurea. And inorganic salts are calcium chloride, lithium chloride, lithium bromide, and tertiary amine is pyridine, quinoline, pyrazine, triethylamine, pyrroline.