KR19990042595A - Polyamide Resin Composition for Film - Google Patents

Abstract

The present invention contains 0.05 to 0.15 wt% of inorganic fine particles having an average particle diameter of 0.1 to 5.0 μm with respect to 100 wt% of a copolymer having a nylon 6 component as a main component, and hexamethylenediamine, adipic acid and tere as an auxiliary component of the copolymer. 0.1-30 wt% of phthalate and isophthalate were added to melt polymerization, and the melt viscosity at 260 ° C. was 6 × 10 ⁻² to 1.3 × 10 ⁴ poise in the shear rate range of 100 to 1000 sec ⁻¹ , and the relative resin viscosity was 2.9 to 3.6, to provide a polyamide resin composition for producing a film and a blend of the copolymer and nylon 6, characterized in that the hot water extract is 0.5% or less, the film produced by the composition of the present invention is characterized in that the surface properties and in particular It can be manufactured to suit the needs of the consumer.

Description

Polyamide Resin Composition for Film

The present invention relates to a polyamide resin composition for films, and more particularly, to a polyamide resin composition having increased stretchability during film processing and improved dimensional stability and transparency of a final product.

Polyamide film has excellent transparency, pinhole resistance, gas barrier property, heat resistance and fluidity, and is widely used in food packaging fields such as meat products or retort foods and other industrial product packaging fields.

However, since polyamide has high hygroscopicity because of many amide bonds in the molecular chain, the activity of the polyamide film decreases and deformation of the film occurs in a humid environment. In order to make up for the shortcomings of the polyamide resin film, the proposed method is to add fatty acid amide to Japanese Patent Application No. 33-9788 to improve the activity of the polyamide film. Since the affinity with the polyamide resin is not easy to disperse, there is a problem in that the thickness variation due to the variation in the active pressure of the film surface and the extrusion pressure during extrusion.

Japanese Patent Application No. 49-42752 proposes a method of improving the surface properties by adding various fine inorganic particles such as amorphous silica (SiO ₂ ) particles, talc, kaolin, and other silicates or by adding a mixture of these additives. have. However, this method causes a problem that the surface glossiness and transparency of the polyamide film are lowered, and that the mechanical strength and gas barrier property of the film are reduced by the voids between the inorganic additives.

In addition, the polyamide film has a disadvantage in that torsion occurs during the hot water treatment for sterilization after food packaging, so that the polyamide film material having improved dimensional stability with excellent physical properties such as transparency, slip, and anti-blocking properties This has been urgently needed. Polyamides are known to be more difficult to stretch than crystalline polymers of other materials due to hydrogen bonding by amide groups in the polymer chain. Substantially, polypropylene can be stretched up to 10 times and polyethylene terephthalate can be stretched up to about 5 times, but polyamide has a disadvantage of being difficult to stretch more than 4 times. This is due to the crystallization that occurs while stretching the polyamide unstretched film, and it is difficult to obtain the degree of orientation proportional to the mechanical draw ratio. When the draw ratio is adjusted to secure the mechanical properties of the final film, breakage occurs during film forming. Make production impossible.

An object of the present invention is to overcome the above-mentioned problems in the prior art, it is possible to produce a film with improved final mechanical properties compared to the conventional polyamide resin composition for film, the final mechanical properties, dimensional stability in the final film product The present invention relates to a polyamide resin composition or blend which can obtain a film having improved transparency and the like.

That is, the present invention is nylon 6, and an inorganic fine particles 0.05 to 0.15% by weight based on 100% by weight of a copolymer composed mainly of an element, a melt viscosity of 260 ℃ 6 × 10 in the shear rate range of 100~1000sec ^{-1 - It} relates to ² to 1.3 x 10 ⁴ poise, relative viscosity of 2.9 to 3.6 and hot water extract of 0.5% or less, and relates to a polyamide resin composition for producing a film or a blend with nylon 6.

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

The resin for producing a film of the present invention comprises a component of nylon 6 as a main component, and at least one member selected from the group consisting of adipic acid, hexamethylenediamine, isophthalic acid and terephthalic acid as an auxiliary component, and this auxiliary component is included in the entire polymer. It is a blend of the polyamide copolymer which occupies 0.1-30 weight%, and nylon 6 and the said copolymer, and the ratio of the polyamide copolymer with respect to homo nylon 6 is 0.1-50 weight%.

Such a resin composition requires a significant melt viscosity in order to maintain film forming stability during processing by a film forming method such as a conventional T-die or inflation method, so that the melt viscosity at 260 ° C. is 100 to 1000 sec. 6 × 10 ² to 1.3 × 10 ⁴ poise in the ⁻¹ range. If the melt viscosity of the polyamide resin is less than 6 × 10 ² at a shear rate of 100 to 1000 sec ⁻¹ , the strength and film forming stability of the film decrease due to the lack of viscosity. On the contrary, 1.3 × 10 ⁴ cells are formed at a shear rate of 100 to 1000 sec ^−1. Exceeding the azus makes it difficult to extrude the polyamide resin and impairs the overall workability. Therefore, in the present invention, it is essential that the melt viscosity of the polyamide resin composition is within the above range.

In general, the polyamide resin film is highly hygroscopic due to the chemical structural properties including a large number of amide bonds in the molecular chain, so it is easy to be deformed during storage or after finishing processes such as lamination in a humid environment. Therefore, the copolymer or copolymer of adipic acid and hexamethylene diamine having a large number of methylene groups in the homo nylon 6 structure of the ball invention and the copolymer and homo nylon 6 lower the average number of amide groups per chain, thereby reducing the hygroscopicity of the conventional nylon 6 homopolymer. You can do it. In addition, by copolymerizing aromatic diacids such as terephthalic acid and isophthalic acid, the arrangement of the main chain is made irregular, thereby suppressing the progress of crystallization of the main chain to ensure transparency, and crystallization during stretching by the two component systems. By suppressing the progression, the stretchability can be increased to improve the workability. Increasing the stretchability improves the orientation and accordingly the degree of orientation increases, so that the arrangement of the polymer chains is similar to the amorphous and crystalline regions, thereby greatly improving the final mechanical properties of the film. Is improved.

The inorganic fine particles that can be used in the polyamide resin composition of the present invention are talc, silica, kaolin, composed of oxides such as silicon (Si), aluminum (Al), magnesium (Mg), calcium (Ca), sodium (Na), It is selected from the group consisting of calcium carbonate and other silicates. When adding the inorganic fine particles, it is important to select an inorganic additive having properties similar in refractive index to the polyamide resin for transparency of the film.

In the present invention, the addition amount of the inorganic fine particles is preferably 0.05 to 0.15% by weight with respect to the polyamide resin, but when the addition amount of the inorganic fine particles is less than 0.05% by weight, the antiblocking property of the film is not sufficiently improved, and the amount is 0.15% by weight. In the case of exceeding the inorganic fine particles aggregate together to cause a decrease in transparency of the film and cause fish-eye. In addition, since the particle size and powdering degree of the inorganic fine particles directly affect the antiblocking property of the final film, in the present invention, the average particle diameter of the inorganic fine particles is 0.1 to 5 μm, and the particles of 1 to 5 μm or more of the total inorganic fine particles are 5 to 5. It is maintained at about 30% to ensure the anti blocking property while doubling the activity of the film to reduce the coefficient of friction of the final film, and does not harm the transparency of the film.

Addition method of the inorganic fine particles to the polyamide resin can be added in the polyamide polymerization step or by dry blending with the polyamide chip (Chip) .In the case of adding the inorganic fine particles in the polymerization step, It may be added at any stage of the end, but is preferably added at the beginning of the polymerization for even dispersion in the polymer of the inorganic fine particles.

In addition, within the range of not impairing the basic physical properties of the polyamide resin composition of the present invention, aliphatic amide compounds used as known lubricants, styrene salts, and nonionic surfactants used as dispersants within the range of 0.1 to 5.0%. It can mix and use.

In the present invention, the polymerization process of the nylon 6 and polyamide copolymer is as follows.

1) First, an aqueous solution of a salt consisting of a mixture of adipic acid and aliphatic diamine is introduced into the reactor. Alternatively, adipic acid and aliphatic diamine may be mixed and added in a monomer state instead of a salt state depending on the reaction method. At this time, hexamethylenediamine is used as the diamine. In addition, terephthalic acid and isophthalic acid may be mixed with the monomers and added according to required physical properties.

2) A constant proportion of caprolactam is introduced into the reactor.

3) Maintain constant pressure while heating the mixture while maintaining pressurized or atmospheric pressure for the reaction and releasing water to the outside at the same time.

4) The polymerization degree is determined by setting the temperature inside the reactor and the reduced pressure conditions at a level having a relative viscosity of 2.9 to 3.6 and a molecular weight distribution ranging from 1.8 to 3.

5) The inside of the reactor is pressurized and discharged while maintaining a constant viscosity.

6) The discharged polymer is made into chips.

7) Managing the hot water extract of the polymer to 0.5% or less The unreacted material is extracted at maximum bath ratio and dried to prepare a chip for preparing the final polyamide film.

Polyamide film molding using the polyamide resin composition for films of the present invention can be produced by a generally known Ti-die method or inflation method. That is, the polyamide resin supplied to the extruder through the hopper is heated and melted, extruded from the extrusion die and then cooled and solidified to prepare an unstretched fabric, and then simultaneously in the traveling direction (MD) and the width direction (TD) of the film. Alternatively, the film may be prepared by heat-setting after successive stretching. At this time, the stretching method of the film can be used both the tenta method and the tube method.

The polyamide composition of the present invention may be processed alone into a film or may be molded by extruding an excellent ethylene vinyl alcohol copolymer (EVOH) and polyamide together in order to further improve the sealability of the final film. Alternatively, the film may be prepared by coating a polyvinylidene chloride (PVDC) having good sealing property on the surface of the polyamide 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

Silica (Fuji Silysiasa Cyroid 310) was added to an aqueous solution of ε-caprolactam 50% by weight and stirred for at least 2 hours to form a uniform dispersion state using a homomixer to prepare a silica dispersion. Filler size is adjusted according to the state of preparation to maintain accuracy to obtain final dispersion. To 100% by weight of the total polyamide copolymer resin, hexamethylenediamine, terephthalic acid, and isophthalic acid salt were added to the reactor by 2% by weight, and the content of silica was added by adding ε-caprolactam and the prepared silica dispersion solution as shown in Table 1. This 0.1% by weight polyamide copolymer was polymerized to prepare a chip. Based on 100% by weight of the prepared polyamide copolymer, a known nonionic surfactant (polyoxyethylene (20) sorbitan mostearate; manufactured by Fuji Japan), an ethylene bis styrate and a styre magnesium salt, which are fatty acid amides, were respectively To the polyamide resin of 0.06%, 0.1% and 0.5% by weight, respectively, were evenly mixed with a dry mixer under a nitrogen atmosphere to prepare a polyamide resin composition for film production.

Subsequently, the product was extruded downwardly using a circular 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. The unstretched film fabric is pressurized between two sets of nip rollers of different speeds, the gas is fed into the tube, and simultaneously biaxially stretched with MD / TD = 3 / 3.2 times. A biaxially oriented film was prepared which was μm.

Next, the stretched film is transferred to the heat-setting tower through the guide roller, and then the low-pressure gas is fed into the film while the heat-fixing tower is 60m / in a tube state so that the film surface temperature is 80 ° C continuously. First heat setting at 180 ℃ for 8 seconds while passing through the minute speed, take out, separate the film into two sheets, contact each film with the second heat treatment roller, second heat setting at 190 ℃ for 5 seconds, and then air-cool to room temperature Winding in odor produced the final polyamide film. The physical properties of the obtained polyamide film were evaluated, and the results are shown in Table 3.

Examples 2-4

Except for changing the composition of the polyamide resin composition in Example 1 as shown in Tables 1 and 2 shown in Table 3 after preparing the polyamide film under the same conditions and methods as in Example 1 to evaluate the physical properties .

Comparative Examples 1 to 4

Except for changing the composition of the polyamide resin composition in Example 1 outside the scope of the present invention as shown in Tables 1 and 2 after the production of a polyamide film under the same conditions and methods as in Example 1, the physical properties of the evaluation It is shown in Table 3.

division Kinds CN-1 CN-2 CN-3 CN-4 CN-5 HN-1 Monomer content (% by weight) ε-caprolactam 98 98 98 90 80 100 Adipic acid 0 0 0 2.5 5 - Hexamethylenediamine One One One 5 10 - Terephthalic acid 0.05 0.05 0.05 2.5 3 - Isophthalic acid 0.05 0.05 0.05 - 2 - Additive content (% by weight) and particle ratio (%) over 1㎛ Silica 0.08,10 0.20,10 0.08,60 0.08,20 0.08,20 0.08,20 Decompression condition (Torr) 250 240 240 240 200 350 Relative viscosity 3.30 3.32 3.32 3.25 3.25 3.40 Melt viscosity (poise × 10, 260 ℃, 1000sec ^-1 ) 3 3.1 3.1 2.9 2.5 2.9 Molecular weight distribution 2.00 2.00 2.00 2.15 2.20 1.98 Hot Water Extract (%) 0.4 0.45 0.45 0.38 0.43 0.40 Melting temperature (℃) 218 218 218 222 222 220 Crystallization temperature (℃) 176 176 176 167 160 184 Glass transition temperature (℃) 45 45 45 43 44 49

division Polyamide composition Copolymer Type Homonylon 6 (HN-1) / Polyimide Copolymer Ratio Example 1 CN-1 0/100 Example 2 CN-4 0/100 Example 3 CN-5 90/10 Example 4 CN-5 0/100 Comparative Example 1 - 100/0 Comparative Example 2 CN-2 0/100 Comparative Example 3 CN-3 0/100 Comparative Example 4 CN-5 40/60

Transparency (%) Static friction coefficient (μ _s ) Film Strain Rate (%) Tensile Strength (kg / ㎠) Hygroscopicity (%) Hot air shrinkage rate (%) Example 1 2.0 0.28 0.5 2600 1.3 1.0 Example 2 2.4 0.27 0.5 2500 1.6 1.1 Example 3 2.8 0.30 0.7 2550 1.8 1.1 Example 4 2.6 0.31 0.5 2400 0.4 1.2 Comparative Example 1 3.1 0.37 4.0 2100 3.0 3.5 Comparative Example 2 6.0 0.30 1.1 2000 3.9 2.0 Comparative Example 3 5.2 0.30 1.7 2100 3.6 2.1 Comparative Example 4 3.5 0.37 3.2 1800 2.2 2.9

Property evaluation method

(1) Transparency: Hayes were measured according to ASTM D-1003.

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

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

Film Strain (%) = (Lf-Lo) / Lo × 100

Lo: 1 pitch length before lamination

Lf: 1 pitch length after lamination

(4) Heat transition temperature: Melting temperature, crystallization temperature, low temperature crystallization temperature, glass transition temperature, etc. were measured by using a thermal analyzer (Perkin-Elmer DSC-7) to increase the temperature and the rate of temperature reduction to 20 ℃ / min, The previous temperature made the maximum point of each peak, and the glass transition temperature made 1/2 the position of heat capacity the value.

(5) Hot water extract: Polyamide resin was measured by weight loss after extraction with hot water at 100 ° C. for 12 hours using an extractor (Soxhlet).

(6) Relative Viscosity: The polyamide resin was dissolved in concentrated sulfuric acid (98%) at a concentration of 0.25 g / dl, and then measured using a Cannon-Fenske viscometer in a 25 ° C thermostat.

Relative Viscosity = The number of seconds of falling water in sec. / Sec. Of pure sulfuric acid in seconds

(7) Molecular weight distribution: Obtained by GPC analysis using a 150-CALC model of Water, Water, solvent and fluid phase using metacresol, the measurement temperature was carried out at 100 ℃.

Molecular weight distribution = weight average molecular weight / number average molecular weight

(8) Melt viscosity: Melt viscosity was measured at 260 ℃ and 100 ~ 1000sec ^-1 shear rate in Capillary Rheometer.

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

(10) Hot air shrinkage rate: After maintaining the film of 20cm × 20cm in hot air at 150 ℃ for 30 seconds, the length change rate in the longitudinal direction and the width direction was measured.

(11) Hygroscopicity: The film of 20cm × 20cm was left at 25 ° C. and 65% relative humidity for 20 minutes and then measured through the weight ratio of the absorbed film.

The laminate film prepared by laminating with a biaxially stretched polyamide film or a polyolefin-based film which can be prepared from the polyamide resin composition of the present invention has excellent physical properties such as surface properties, transparency, slip properties, etc. It can also be used as a packaging material for industrial products. In addition, the laminate film has an advantage that it can be used without deformation during the post-processing process and other hot water treatment for sterilization because the film strain in all directions is 2% or less.

Claims (4)

Capable of 70 to 99.9% by weight of caprolactam, a nylon 6 component, and 0.1-30% by weight of one or more mixtures selected from the group consisting of hexamethylenediamine, adipic acid, terephthalate and isophthalate It contains 0.05 to 0.15% by weight of inorganic fine particles having an average particle diameter of 0.1 to 5.0㎛ with respect to 100% by weight of the copolymer prepared, the melt viscosity of 260 ℃ in the shear rate range of 100 ~ 1000sec ^-1 6 ~ 10 ^-2 to It is 1.3 * 10 <^4> poise, the relative viscosity 2.9-3.6 and the hot-water extraction fraction are 0.5% or less, The polyamide resin composition for film manufacture of these. The polyamide resin composition for film production according to claim 1, wherein the inorganic fine particles are selected from the group consisting of silica, kaolin, talc, alumina or a mixture of two or more thereof. The polyamide resin composition for producing a film according to claim 1 or 2, wherein the inorganic fine particles have an average particle diameter of 1 µm or more so that the inorganic fine particles become 5 to 30% of the total inorganic fine particles. A blend of homo nylon 6 and the polyamide copolymer of claim 1, wherein 0.1 to 50% by weight of the copolymer is blended with respect to homonylon 6.