KR100203526B1 - The preparation method of polyamide film - Google Patents

Abstract

The present invention relates to a method for producing a polyamide film, and in particular, at least one diamine compound such as aliphatic diamine and aromatic diamine, and at least one dikilic acid compound such as aliphatic dikiric acid and aromatic dicarbosilic acid. Preparation of Sequential Biaxial Polyamide Films with Excellent Mobility and Stretchability by Addition of Inorganic Particles to Polyamide Made by Polymerizing 1 to 10% by Weight of Polyamide Forming Components and 90 to 99% by Weight of Epsilon Caprolactam It is about a method.

Description

Process for producing polyamide film

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polyamide film. Specifically, at least one diamine compound such as aliphatic diamine and aromatic diamine and at least one dikyric acid compound such as aliphatic dikiric acid and aromatic dikiric acid 1 to 10% by weight of the polyamide-forming component and 90 to 99% by weight of epsiloncaprolactam were prepared by adding inorganic particles to the polyamide formed by polymerizing. It relates to a manufacturing method.

Polyamide resins have excellent mechanical properties and are widely used as materials for fibers and films. In particular, biaxially stretched polyamide films have been widely used as food packaging materials due to their excellent gas barrier properties.

In general, the biaxially stretched film processing method is a method of stretching the unstretched film in a mutually perpendicular direction to improve the mechanical properties of the film. The biaxially stretched film processing method is divided into a sequential biaxial stretching method and a simultaneous biaxial stretching method according to the time points in which the longitudinal and transverse stretching are performed. Sequential biaxially oriented film processing is a method of stretching an unoriented film in a longitudinal direction and then stretching it laterally. A hydrogen bond forming functional group in a molecular chain such as a polyester film represented by polyethylene terephthalate or a polyolefin film represented by polypropylene is used. As a processing method that is mainly used for film processing of polymers that do not contain, it is possible to give various stretching conditions as compared to the simultaneous biaxial stretching method, and the installation and operation of the device have economic advantages.

Polyamide films are not easy to produce a film by the sequential biaxial stretching method. In the case of producing a film of polyamide resin by the axial biaxial stretching method in which the stretching in the transverse direction and the longitudinal direction is sequentially performed, stretching the polyamide resin in the longitudinal direction causes the molecular chains to be arranged in the same direction. At this time, the amide bonds in the molecular chain easily form hydrogen bonds with the amide bonds in the other molecular chain, and the direction of the hydrogen bond becomes the transverse direction in the vertical direction of the longitudinal direction. The hydrogen bonds formed in the transverse direction change the magnitude of the stretching stress in the longitudinal direction, resulting in uneven stretching (permanent necking is left) or breakage of the film.

As a representative method for solving the problems occurring during the sequential biaxial stretching of the polyamide resin, it is possible to modify the polyamide resin itself to be biaxially stretched. As a method of modifying such a polyamide resin, a method of copolymerizing nylon 6.6 or amorphous nylon 6 with an appropriate copolymerization component or blending (mixing and extruding) with another type of polymer is generally performed. This allows other types of polyamides to interfere with the molecular orientation of the aliphatic polyamides and to prevent the formation of hydrogen bonds that occur during stretching in the longitudinal direction, thus weakening the bond strength between the molecular chains, thereby allowing the stretching in the transverse direction.

Another method for producing the polyamide film by the sequential biaxial stretching method is to enable the transverse stretching of the crystal form of the inner molecular chain of the polyamide film, which is stretched in the longitudinal direction.

For example, Japanese Patent Application Laid-Open No. 53-18669 shows transverse stretching so that the plane orientation index obtained using X-ray in the α-type aliphatic polyamide or polyamide mixture is in the range of 0.8 to 1.3 in the longitudinal stretching. The sequential biaxial stretching manufacturing method of the polyamide film performed by doing is disclosed.

However, the films produced by the conventional biaxial stretching method of such polyamides have a problem of lack of surface activity.

As a method for imparting surface activity to a polyamide film, there is a method of improving surface crystallinity of a film by coating an organic material on the surface of a film or raising the temperature of a casting roll to improve the crystallinity of the sheet.

However, each of these methods is not preferable because of the following problems. That is, the method of imparting the active activity to the surface of the film by coating the organic material on the surface of the film has a problem that the dispersibility of the organic material is a problem, the physical properties of the final film is lowered, raising the crystallinity by raising the temperature of the casting The method is disadvantageous in that adhesion of monomers or oligomers to the casting rolls is severe and a uniform sheet cannot be obtained. Accordingly, a method of embossing the surface of the film after the stretching process of the film has been proposed, but an expensive additional equipment is required, which is not economically desirable.

The present invention has been made to solve the above problems, composed of one or more diamine compounds of aliphatic diamines, aromatic diamines and one or more dikyric acid compounds such as aliphatic dikilic acid, aromatic dicarboxylic acid The isothermal crystallization rate parameter (t / 2) _o / (t / 2) _c }, measured at 190 ° C, in a polyamide made by polymerizing 1 to 10% by weight of a polyamide forming component and 90 to 99% by weight of an aliphatic lactam compound, is 0.8. Provided is a method for producing a sequential biaxial polyamide film comprising an inorganic particle so as to be 2.0 so as to be extruded through a tee-die and sequentially stretched.

As the aliphatic diamine or aromatic diamine compound used in the present invention, meta-xylenediamine, para-xylenediamine, hexamethylenediamine, 2,2,4,2, '4', 4 '-Trimethylhexamethylene diamine (2,2,4,2', 4, '4'-trimethylhexamethylene diamine), 1,3-bisaminomethylcyclohexane, bis-p-aminocyclohexyl Methane (bis-p-aminocyclo-hexylmethane) and the like, and dikiric acid, adipic acid, sebacic acid, subberic acid, pimeline acid, isophthalic acid, terephthalic acid, 2,6-naphthalenedikyric acid, etc. There is this.

As the aliphatic lactam, epsilon caprolactam, caprylactame, and laurylactam can be used.

When the polyamide-forming component to be polymerized with aliphatic lactam is 10% by weight or more, dimensional stability, heat resistance, chemical resistance, and mechanical strengths are lowered. If it is 1% by weight or less, there is a problem in elongation such as an increase in stretching stress and breakage.

In addition, in this invention, the crystallization parameter of a polyamide becomes a very important factor which determines the sequential biaxial stretchability of a polyamide. As for the parameter of the polyamide crystallization which is preferable in this invention, it is preferable that the isothermal crystallization parameter {t / 2) _o / (t / 2) _c } measured at 190 degreeC will be 0.8-2.0. If the parameter is 0.8 or less, there is no problem in terms of stretchability, but there is a problem in that this activity is poor.

As the inorganic particles used in the present invention, talc, silica, calcium carbonate, aluminosilicate, or kaolin are used, and the particle diameter is preferably about 1 to 5 µm. If the particle size is less than 0.1 µm, the activity is not sufficiently improved. If the particle size exceeds 5 µm, the film surface projections become large and the surface glossiness is lowered. In the case of a thin stretched film having a thickness of about 15 μm, classification and dispersion are necessary so as not to actually contain particles of 10 μm or more in order to prevent breakage of the film during stretching. The amount of the inorganic particles to be added is within the range such that the crystallization parameter {t / 2) _o / (t / 2) _c } of the polyamide is 0.8-2.0. In addition, you may mix | blend a coloring agent, antioxidant, a heat stabilizer, a weathering imparting agent, an antistatic agent, etc. as needed.

In the case of adding the inorganic particles to the polyamide, it may be added to the polyamide raw material before polymerization or at any stage after the polymerization residual. It is also possible to add to the polyamide in the hopper after polymerization or before shaping into chips or before extrusion. In the case where the inorganic particles are added to the raw material of the polyamide before polymerization, the inorganic particles are preferably dispersed after being dispersed in water or an aqueous solution of a raw material of 10 to 80% by weight of polyamide.

In addition, a method of preparing a polyamide composition containing inorganic particles at a high concentration of 1.0% or more in advance, and suitably blending it with the polyamide before shaping the polyamide may be used. Then, in the process of obtaining a film, the obtained mixture is extruded by a tee-die at the extrusion temperature of 220-300 degreeC, and cooling is performed on the casting roll surface. At this time, when the temperature of the casting roll is high, it is advantageous to obtain a flat unstretched sheet, but the degree of adhesion of monomers or oligomers to the casting roll increases, which is disadvantageous in obtaining a uniform unstretched sheet and in terms of transparency. The suitable temperature range for the casting roll is 10 to 50 ° C. The unstretched sheet is successively biaxially stretched at a stretching temperature of 50 to 180 ° C, and is preferably heat treated by relaxing 0 to 10% in a temperature range of 120 ° C or more and 10 ° C lower than the melting point for 3 to 30 seconds as necessary.

Next, the present invention will be described in more detail with reference to preferred embodiments of the present invention. However, the following examples are provided only to more easily understand the present invention, and the present invention is not limited to these examples.

Example 1-3

ε-caprolactam 6000g and methaxylene diamine 85.9g Idipic acid was added to the silica powder with a particle size of 3㎛ as shown in Table 1, and polymerized in the temperature range of 180-270 ℃ 0.3% by weight, relative viscosity 2.8 After obtaining phosphorus resin, the temperature of the cooling roll was 20 degreeC, and it extruded on the sheet | seat through the tee-die, and the sheet | seat of 150 micrometers in thickness was produced. The sheet was stretched 3.2 times at 60 ° C. in the longitudinal direction and 3.5 times in the transverse direction at 72 ° C. to give 5% relaxation for 10 seconds at 200 ° C. to prepare a polyamide biaxially stretched film.

Comparative Example 1-3

In Examples 1 to 3 described above, the composition of the resin, the amount of crystallization agent and the degree of crystallization were prepared as shown in Table 1 below, and the polyamide biaxially oriented film was prepared by treating the same as Examples 1 to 3 substantially. It was.

The polyamide biaxially oriented films obtained in the above Examples 1 to 3 and Comparative Examples 1 to 3 were evaluated in the process of elongation, friction characteristics, etc. by the following method, and the results are shown in the following table.

(Assessment Methods)

1. Crystallization Rate Parameters

10 mg of the sample was heated at a temperature increase rate of 10 ° C./min to reach 265 ° C., then maintained for 3 minutes, and then cooled to 190 ° C. at a rate of −30 ° C./min. The time at which crystallization starts is called t ₀ . The time at which ΔHc is completely crystallized and ΔHc is 1/2 is called t / 2. When t / 2 of nylon-6 without addition of inorganic particles is (t / 2) / ₀ and t / 2 of polyamide copolymer with addition of inorganic particles is (t / 2) _c , (t / 2 ) The ratio of ₀ / (t / 2) _c was defined as the crystallization rate parameter.

2. active activity

Based on ASTM D-1894-63, the static friction coefficient was measured and shown in the atmosphere of 20 degreeC and 65% of a relative humidity.

3. Extensibility

It was evaluated by the number of breaks of the film during the stretching process of the film for 8 hours.

○: less than 1 time, △: 2 times, ×: 3 times or more

Claims (5)

1 to 10% by weight of a polyamide-forming component composed of one or more diamine compounds such as aliphatic diamines and aromatic diamines and one or more dikyric acid compounds such as aliphatic dikilic acids and aromatic dicarboxylic acids and aliphatic lactam compounds 90 The polyamide made by polymerizing the polymer to 99% by weight contained inorganic particles such that the isothermal crystallization rate parameter {(t / 2) ₀ / (t / 2) _c } measured at 190 ° C. was 0.8 to 2.0 to form a thi-die. The manufacturing method of the sequential biaxial polyamide film which carries out extrusion and sequential stretching through. The method of claim 1, wherein the inorganic particles are selected from at least one selected from the group consisting of talc, silica, calcium carbonate, aluminosilicate, or kaolin. The method according to claim 1 or 2, wherein the inorganic particles have an average particle diameter of about 1 to 5 mu m. The method according to claim 1 or 2, wherein the inorganic particles are added to the polyamide raw material before polymerization in addition to the polyamide, at any stage after the polymerization reaction, or after molding or before molding into chips. Or adding to the polyamide in a hopper before extrusion. 5. The method according to claim 4, wherein the inorganic particles are added to the raw material of the polyamide before polymerization, after the inorganic particles are dispersed in water or an aqueous solution of the raw material of the polyamide in an amount of 10 to 80% by weight.