KR100240447B1 - Polyamide resin composition for using as film - Google Patents

Abstract

The present invention is a polymerization process of 0.01 to 1.0% by weight of a layered silicate having a thickness of 6 to 20 mm and a length of 0.002 to 1 μm to a polyamide copolymer, and 0.05 to 0.3% by weight of inert inorganic fine particles having an average particle diameter of 0.1 to 5 μm. The present invention relates to a polyamide resin composition for a film, wherein the content of the final inorganic material is 0.06 to 1.3% by weight, wherein the polyamide film prepared by the polyamide resin composition of the present invention has a gas barrier property and a tensile strength. It not only has excellent dimensional stability, but also has excellent advantages such as anti-blocking property and activity.

Description

Polyamide Resin Composition for Film

The present invention relates to a polyamide resin composition for a film, and more particularly, to a film that can further improve gas barrier properties, dimensional stability, transparency, and activity of a final film by adding a layered silicate and an inorganic fine particle in a polyamide polymerization step. It relates to a polyamide resin composition.

Polyamide film is not only excellent in pinhole resistance, gas barrier property, but also excellent in heat resistance, cold resistance, and mechanical strength, and is mainly used for vacuum packaging of ham, meat products and aquatic products, and is widely used in other industrial product packaging fields.

However, the polyamide film is a printing process for the polyamide film used in food packaging since the rigidity of the film decreases with temperature during the printing, lamination, and the like, and the defects of the printing focus or printing standard are likely to occur. Stable dimensional stability and improved gas barrier properties are required for environmental changes during post-processing, such as lamination and curing processes.

On the other hand, due to the large number of amide bonds in the polyamide molecular chain, the hygroscopicity is high, so that the activity of the polyamide film decreases, the deformation of the film occurs in the humid environment, and the gas permeability increases with the diffusion of water. Degrades.

As a method for compensating the disadvantages of such a polyamide resin film, Japanese special public service 49-42752 adds various fine inorganic particles such as amorphous silica (SiO ₂ ), talc, kaolin, and other silicates, or It is proposed to improve the surface properties by adding a mixture of. However, in this case, the surface glossiness and transparency of the polyamide film are lowered, and the mechanical strength and gas barrier property of the film are reduced by the voids between the inorganic additives.

In addition, Japanese Patent Publication No. 3-262633 proposes a method of using layered silicate as a method for increasing the mechanical strength and gas barrier property, but this method does not define an appropriate content of layered silicate. Since the use of the layered silicate added to the amide is applied to the film as it is, there is a problem that the film does not have the anti-blocking properties, which is a characteristic that should be basically.

SUMMARY OF THE INVENTION An object of the present invention is to overcome the above-mentioned problems of the related art, and to provide a polyamide resin composition capable of producing a film having excellent dimensional stability, gas barrier property, activity, and anti blocking property in a final film product. will be.

That is, in the present invention, a layered silicate having a thickness of 6 to 20 mm and a length of 0.002 to 1 μm is added to 0.01 to 1.0% by weight of the polyamide and 0.05 to 0.3% by weight of the inert inorganic fine particles in the polymerization process so that the content of the final inorganic material is 0.06 to 1.3. It is related with the polyamide resin composition for films characterized by the weight%.

Hereinafter, the present invention will be described in detail.

The polyamides that can be used in the present invention include polymers obtained from ε-caprolactam, 6-aminocaproic acid, ε-aminoundecanoic acid, 9-aminononanoic acid, α-piperidone, and the like, or monomers of the single polymer. As a copolymer, diamines such as hexamethylenediamine, nonamethylenediamine, undecamethylenediamine, dodecamethylenediamine, and methaxylenediamine and dicarboxylic acids such as terephthalic acid, isophthalic acid, adipic acid and sebacic acid can be obtained by condensation. Polymer.

The layered silicate constituting the polyamide resin composition of the present invention is a flat sheet having a thickness of 6 to 20 GPa and a length of 0.002 to 1.0 µm, and the raw material is montmo as a layered silicate mineral composed of a layer of magnesium silicate and aluminum silicate. Lilonite, saponite, bentonite, phyriterite, monterolite, hectorite and the like.

The role of the layered silicate in the polyamide resin in the present invention is to ultra-disperse the layered silicate in nanometer units through pretreatment to make the rigidity and gas barrier properties better than the general filling composite. The layered silicate is swelled into an organic layered silicate through a cation exchange reaction before the polymerization to allow the monomer to penetrate in the middle of the organic layered silicate to proceed with the polymerization reaction.

As the swelling agent used in the present invention, an acid compound such as acetic acid, phosphoric acid, hydrochloric acid, hypophosphoric acid, and an amino acid such as 12-aminododecane acid, caproic acid, caprolactam, or the like can be used.

The blending amount of such a fungal acid salt is preferably 0.01 to 1.0% by weight based on polyamide, and when the blending amount is less than 0.01% by weight, the effect of improving the physical properties such as gas barrier property, rigidity, and hygroscopicity is less than 1% by weight. The transparency of the film is lowered and the rigidity at the time of stretching is increased, making high magnification stretching difficult.

Inert inorganic fine particles used in the present invention include talc, silica, kaolin, calcium carbonate, and the like composed of oxides such as silicon (Si), aluminum (Al), magnesium (Mg), calcium (Ca) and sodium (Na). Silicates and the like.

The addition amount of the inert inorganic fine particles is preferably 0.05 to 0.15% by weight relative to the polyamide resin, but when the addition amount of the inorganic fine particles is less than 0.05% by weight, the antiblocking properties of the film are not sufficiently improved, and when the amount of the inert inorganic particles is more than 0.15% by weight, Particles agglomerate with each other, the transparency of the film is also lowered, causing fish-eye (yeye) mechanical properties are lowered.

In addition, since the particle size of the inorganic fine particles directly affects the antiblocking property of the final film, the average particle diameter of the inorganic fine particles is preferably 0.1 to 5㎛, which doubles the activity of the film while securing antiblocking property to the final film. This reduces the coefficient of friction and does not impair the transparency of the film.

In the present invention, the addition method of the layered silicate and the inert inorganic fine particles to the polyamide resin is most preferably added in the polyamide polymerization step. In order to swell the layered silicate in the polymerization step, and to evenly disperse the monomer in the polymerization product of the inert inorganic fine particles, it is preferable to be added at the initial stage of the polymerization.

In addition, the aliphatic amide-based compound used as a lubricant, the non-ionic interfacial sulfuric agent used as a dispersant, and the like within the range of 0.1 to 5% by weight, without impairing the basic physical properties of the polyamide resin composition of the present invention. It can mix and use.

In the production of the polyamide resin composition for a film of the present invention, the polymerization step of the polyamide copolymer is as follows.

1) First, the layered silicate is swelled with aminoacids such as 12-aminododecane acid, caproic acid, caprolactam, etc. and;

2) after dispersing the inert minerals in another preparation;

3) adding an aqueous layered silicate and an aqueous dispersion of an inert inorganic material simultaneously so as to maintain the moisture content at a ratio of 0.1 to 3% by weight relative to the polyamide monomer when using an atmospheric column;

4) adding an aqueous dispersion of organic layered silicate and an inert inorganic material to maintain the moisture content at a ratio of about 7 to 15% by weight when using a pressure column;

5) Maintain pressurized or atmospheric pressure for the reaction and maintain a constant pressure while heating the mixture while simultaneously releasing water out.

6) The polymerization degree is determined by setting the temperature inside the reactor and the reduced pressure conditions such that the polymer has a relative viscosity of 2.9 to 3.6 and a molecular weight distribution of 1.8 to 3.

7) evacuating the reactor at atmospheric pressure and maintaining a constant viscosity;

8) The polymer is manufactured into chips, and the unreacted materials are extracted in the maximum bath ratio in order to manage the hot water extraction fraction of the polymer to be 0.5% or less, followed by drying to prepare chips for producing the final polyamide film.

The polyamide film molding using the above-mentioned polyamide composition for film can be performed by generally known T-die method or inflation method. In detail, the polyamide-based resin supplied to the extruder through the hopper is heated and melted, then extruded from the extrusion die, and then cooled and solidified to prepare an unstretched fabric, and then the film's advancing direction (MD) and width direction (TD). ) And then stretched simultaneously or sequentially in a denta method or a tube method, and heat-set to produce a film.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited by the following Examples.

Example 1

Using a homomixer, an organic layered silicate aqueous solution was prepared by uniformly dispersing 3% by weight of montmorillonite 1% by weight of phosphoric acid in 80% solution of ε-caprolactam at 80 ° C, and using silica (Fuji Silysia Co., Ltd.) Lloyd 310) was added to 50% aqueous solution of ε-caprolactam and stirred for at least 2 hours to achieve a uniform dispersion state using a homomixer to prepare a silica dispersion of 10% by weight. The organic layered silicate is added in an amount of 0.05% by weight and 0.1% by weight of silica with respect to 100% by weight of caprolactam, followed by condensation polymerization to obtain a polyamide resin for film. 0.01% by weight of a known nonionic surfactant (polyoxyethylene (20) sorbitan monosterate; manufactured by Japan Oil & Fat Co., Ltd.) with respect to 100% by weight of the produced polyamide resin, 0.1% by weight of ethylene bis styrate which is a fatty acid amide, and a steer 0.5 wt% of the late magnesium salt was evenly mixed in a dry mixer under a nitrogen atmosphere to prepare a polyamide resin composition for film production.

Subsequently, it was extruded downwardly using an annular die having a diameter of 400 mm at 250 ° C. through an extruder and quenched with water at 15 ° C. to obtain an unstretched film fabric.

A pressurized gas is fed into a tube between two sets of nip rollers having different speeds from the unstretched film fabric and simultaneously biaxially stretched with MD / TD = 3 / 3.2 times to obtain a film diameter of 700 mmΦ and a thickness of 15 µm at a film surface temperature of 80 ° C. A biaxially oriented film was prepared.

Next, the stretched film is transferred to a heat setting tower through a guide roller, and then a low pressure gas is introduced into the film, and the heat setting tower is 60m / min so that the film surface temperature is 80 ° C continuously with the previous stretching process in a tube state. After passing through the speed at 180 ° C for 8 seconds, primary-heating and folding, and then separating the film into two sheets, each film is heat-set and secondaryly fixed by the second heat treatment roller, and then folded into two sheets of each film Was subjected to a second heat treatment roller and heat-fixed at 190 ° C. for 5 seconds, and then air-cooled to room temperature to be wound up in a winder to prepare a final polyamide film, and the physical properties of the resulting polyamide film were evaluated. 2 is shown.

[Examples 2-3]

Except for changing the components of the polyamide resin composition in Example 1 as shown in Table 1 below, a polyamide film was prepared in the same manner as in Example 1, and the physical properties thereof are shown in Table 2 below.

[1 ~ in comparison]

Except for changing the components of the polyamide resin composition in Example 1 as shown in Table 1, a polyamide film was prepared in the same manner as in Example 1, and the physical properties thereof are shown in Table 2 below.

[Property evaluation method]

(1) Transparency: The haze was measured according to ASTM D-1003.

(2) Friction coefficient: In accordance with ASTM D-1894, the static friction coefficient was measured using a friction coefficient measuring instrument at 20 ° C. and a relative humidity of 65%.

(3) Film Strain: The polyamide film was slit to the required width, printed, laminated with polyethylene, and then the printed pitch (Pitch, based on 360 mm) was measured, and the film strain was measured using the following equation.

(L _f -L _o ) / L _o × 100 = (%)

L _o : 1 pitch length before lamination

L _f : 1 pitch length after lamination

(4) Tensile strength: in accordance with ASTM D-882 was measured using a universal tensile tester at 20 ℃, 65% relative humidity atmosphere.

(5) Hygroscopicity: The film of 20cm × 20cm was measured through the weight ratio of the absorbed film after standing for 20 minutes at 25 ℃, 65% relative humidity.

(6) Gas Permeability: According to ASTM D-3985-81, the gas permeability of the film was measured at 23 ° C and 0% relative humidity.

As described above, the biaxially stretched polyamide film prepared from the polyamide resin composition of the present invention has a polyamide film because layered silicates exist in a layered direction in the polymer matrix to prevent diffusion of a gas such as oxygen. It can increase gas barrier property, and it reduces free volume in the polymer, so it prevents the diffusion of water vapor and decreases the moisture absorption rate. Will be.

In addition, 0.1 to 5㎛ inert inorganic material is uniformly dispersed to increase the anti-blocking properties and surface activity of the film that can not be secured only by layered silicate to maximize the trouble that can occur during the winding or unwinding (winding or unwinding) It can be removed. Therefore, the laminate film produced by laminating with a biaxially stretched polyamide film or a polyolefin-based film prepared from the polyamide resin composition of the present invention has excellent physical properties such as surface properties, gas barrier properties, dimensional stability, activity, etc. It can be used as a packaging material for materials and other industrial products, and the laminate film has an advantage that it can be used without deformation even in the post-processing process and other hot water treatment for sterilization because the film deformation rate in all directions is 2% or less. .

Claims (4)

To the polyamide copolymer, a layered silicate having a thickness of 6 to 20 mm and a length of 0.002 to 1 μm was added to the polyamide in a polymerization process, in which 0.01 to 1.0 wt% of the inert inorganic particles having an average particle diameter of 0.1 to 5 μm were added in the polymerization process. Polyamide resin composition for a film, characterized in that the content of the inorganic material is 0.06 to 1.3% by weight. 2. The layered silicate mineral, montmorillonite, saponite, bentonite, phyritelite, monterolite, hectorite, according to claim 1, wherein the layered silicate is composed of a layer of magnesium silicate and aluminum silicate. Polyamide resin composition for a film, characterized in that selected from the group consisting of. The method of claim 1, wherein the inert inorganic fine particles are made of talc, silica, kaolin, calcium carbonate, silicate composed of silicon (Si), aluminum (Al), magnesium (Mg), calcium (Ca), sodium (Na). Polyamide resin composition for films, characterized in that selected from the group. The cation exchange medium of the layered silicate is selected from the group consisting of 12-aminododecane acid, caproic acid, caprolactam and acid compounds such as acetic acid, hydrochloric acid, phosphoric acid and hypophosphorous acid. Polyamide resin composition for films, characterized in that.