KR101070800B1 - Polyamide film - Google Patents

Abstract

The present invention relates to a polyamide film, by providing a polyamide film including the barium sulfate fine particles coated with an inorganic compound as an inorganic filler, it is excellent in running performance and does not reduce transparency, which contributes to a reduction in manufacturing cost and an improvement in production speed. It is an invention that can be.

Polyamide, Inorganic Compound, Barium Sulfate

Description

Polyamide film {Polyamide film}

The present invention relates to a polyamide film.

Polyamide films have excellent transparency, pinhole resistance, gas barrier property, heat resistance, oil resistance, and the like, and are widely used in food packaging fields such as meat processed foods or retort foods, and other industrial product packaging fields.

In general, however, polyamide films have high hygroscopicity because of the large number of amide bonds in the molecular chain. As a result, the number of surface adsorption water increases as the moisture absorption increases, and as a result, there is a problem that the running performance deteriorates. Such deterioration of runability has caused obstacles in post-processing processes such as slitting, printing, deposition, and lamination.

Accordingly, in order to improve the running property of the polyamide film, an inorganic filler is usually added to the polyamide composition in the film forming process, the post-processing and the use process of the polyamide film to form fine unevenness on the surface of the film. This is a concept that gives the running property by reducing the friction coefficient of the film surface by creating irregularities by the filler on the surface. Usable fillers are usually kaolin, talc, calcium carbonate, silica, titanium dioxide, clay, alumina, calcium silicate. And insoluble particles such as mica and the like, and the film prepared by adding them has various fine surface structures depending on the type, size and amount thereof.

When the amount of the filler is increased, fine irregularities are formed on the surface of the film, and thus the running property of the film is improved, but the transparency of the film is deteriorated. In addition, when the film is formed into a film, protrusions are formed on the surface of the film due to the filler, which causes scattering of light, which is another cause of lowering transparency of the film. On the other hand, if the content of the filler is lowered, the draw nonuniformity due to the blocking problem due to the difficulty in securing the runability in the film forming process, and a problem of pulling to one side during slitting occurs.

In order to solve this problem, a method of applying an active material to the surface of the film while minimizing the amount of the inorganic filler has been developed and used in order to improve the running performance without reducing the transparency of the polyamide film. This has the advantage of being able to produce a high transparency film while solving the blocking phenomenon, but since one coating process is added in addition to the existing film manufacturing process, the manufacturing cost of the film is increased, production speed is reduced, process management difficulty, solvent There is a problem such as degradation of workability due to the use of.

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

The present invention has been made to solve the above problems, and an object thereof is to provide a polyamide film having improved runability and preventing transparency decrease due to the addition of an inorganic filler.

It is another object of the present invention to provide a polyamide film that maintains excellent running and transparency even without applying a separate active material on the surface of the film.

The present invention provides a polyamide film comprising a barium sulfate fine particle coated with an inorganic compound as an inorganic filler.

The inorganic compound is characterized by containing aluminum or silicon.

The inorganic compound is characterized by using 0.5 to 10 parts by weight based on 100 parts by weight of the barium sulfate fine particles.

The inorganic filler is characterized in that the particle size is 0.1 ~ 5㎛, 5 ~ 30% by weight of the fine particles having a particle size of 1㎛ or more of all the fine particles, 0.05 to 1 parts by weight based on 100 parts by weight of polyamide resin.

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

The polyamide film of the present invention contains an inorganic filler in the polyamide resin, and in particular, the inorganic filler is characterized by using barium sulfate fine particles coated with an inorganic compound.

The barium sulfate has a similar refractive index with that of the polyamide resin as compared to talc, silica, kaolin, calcium carbonate, silicate, and the like, which are conventionally used as inorganic fillers. Therefore, when the barium sulfate fine particles are used as the inorganic filler in the polyamide resin, Transparency does not fall.

However, the barium sulfate has a problem in compatibility with the polyamide resin, so it is not easy to disperse it in the polyamide resin. In order to improve such a problem, the barium sulfate is coated with an inorganic compound by coating the surface of the barium sulfate fine particles with an inorganic compound. use. The inorganic compound is not particularly limited as long as it is a compound having excellent compatibility with the polyamide resin, but may be coated with an inorganic compound containing aluminum or silicon in consideration of the refractive index with the polyamide resin.

In addition, coating the surface of the barium sulfate with an inorganic compound containing aluminum or silicon improves the adhesion to the polyamide resin, and changes the refractive index caused by the generation of voids at the interface between the additive and the polyamide resin in the stretching process during film production. The problem of the fall of transparency can be prevented.

The inorganic compound is preferably coated using 0.5 to 10 parts by weight based on 100 parts by weight of the barium sulfate fine particles, and the method of coating the inorganic compound on the surface of the barium sulfate fine particles is not particularly limited.

In the present invention, the inorganic filler preferably has a particle diameter of 0.1 to 5.0 μm, but when the particle size of the inorganic filler is less than 0.1 μm, the surface energy of the barium sulfate particles increases, causing a problem of coagulation with each other. The blocking phenomenon occurs and the running performance is deteriorated. On the contrary, when the particle size exceeds 5.0 μm, roughness of the final film surface becomes poor, and the appearance of the film by the inorganic particles is deteriorated. There exists a problem that transparency and dispersibility fall. In particular, it is desirable to maintain 5-30% of the fine particles having a particle size of 1 μm or more among the total fine particles so as not to impair the transparency of the film while doubling the activity of the film while reducing the anti-blocking property while reducing the coefficient of friction of the final film.

The addition amount of the said inorganic filler is 0.05-1 weight part with respect to 100 weight part of polyamide resins, More preferably, it is 0.07-0.25 weight part. If the amount of the barium sulfate fine particles added to 100 parts by weight of the polyamide resin is less than 0.05 parts by weight, the surface roughness becomes insufficient, so that it is difficult to obtain good runability, and if it is more than 1 part by weight, the transparency of the film is deteriorated.

In addition, the present invention may include a dispersant for dispersing the inorganic filler. As an example of a suitable dispersant, Sodium Tripolyphosphate (STPP) or Kallium Tripolyphosphate (KTPP) may be used, and the amount of addition may be 0.1 to 5 parts by weight based on 100 parts by weight of barium sulfate fine particles, and more preferably 0.5 to 2 parts by weight. It is good. When the amount of the dispersant added to the barium sulfate fine particles is less than 0.5 parts by weight, it is difficult to obtain desired dispersibility such as aggregation of barium sulfate as fine particles. When the amount of the dispersant is more than 2 parts by weight, the physical properties of the film are not only lowered but also economically unfavorable.

The polyamide resins usable in the present invention are not particularly limited, and polyamide resins such as nylon 6, nylon 7, nylon 11, nylon 12, nylon 66, nylon 6T, nylon MXD6, nylon 46 and the like Copolymers, resin mixtures, polymer alloys, and the like.

The haze value of the polyamide film thus obtained is appropriately 2.0 or less in consideration of the transparency of the film.

In addition, the dynamic friction coefficient of the polyamide film of the present invention is preferably 0.3 to 0.6 or less at 60% relative humidity in consideration of processability and ease of winding.

Polyamide film molding using the polyamide resin composition for films of the present invention can be carried out by a generally known T-die method or inflation method. For example, the polyamide-based resin supplied to the extruder through a hopper is heated and melted and then extruded from the extrusion die, and then cooled and solidified to prepare an unstretched fabric, and then the advancing direction (MD) and width direction ( TD) can be simultaneously or sequentially drawn and then heat-fixed to produce a film. At this time, both the tenter method and the tube method can be used as a method of stretching the film.

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

≪ Example 1 >

ε-caprolactam was added to the reactor, 4 parts by weight of distilled water was added to 100 parts by weight of ε-caprolactam, melted at 85 ° C, and stirred at 60 rpm or more. Upon stirring, the system was always filled with nitrogen to prevent oxidation.

Barium sulfate particles (trade name: hombright, Germany, manufactured by Sachtleben Chemie GnbH) surface-modified by coating the homomixer with aluminum oxide (Al ₂ O ₃ ) were added so as to 0.07 part by weight with respect to 100 parts by weight of the polyamide resin, and a dispersant (STPP) : 1 part by weight of sodium tripolyphosphate) is added to 100 parts by weight of the surface-modified barium sulfate fine particles, and mixed with distilled water so that the solid content of the barium sulfate fine particles and the dispersant is 10 wt% Into the reactor.
The surface-modified barium sulfate fine particles have a particle size ranging from 0.1 μm to 5.0 μm, and the average particle size is adjusted to 0.7 μm by controlling particles having a particle size of 1 μm or more from 5 to 30 wt%.

The mixture introduced into the reactor was stirred to raise the temperature to 250 ° C., maintaining the pressure at 17.5 kgf / cm 2, and reacting for 1 hour. The pressure in the reactor was slowly removed for 1 hour to create an atmospheric pressure, and the polymerization was completed by depressurizing for 30 minutes at a pressure of 0.3 kgf / cm 2. At this time, the polymerization temperature and the vacuum degree were adjusted so that the relative viscosity of the polymer is 1.9 ~ 3.9. After the polymerization was completed, the polymer was discharged by pressurization of 3kgf / cm 2, which was prepared as a chip, washed with hot water at 95 ° C. for 12 hours to remove unreacted material, and then vacuum dried at 100 ° C. The moisture content of the dried chip was 0.5% by weight or less to prepare an unstretched sheet using a melt extruder at a temperature of 250 ℃. At this time, the temperature of the cooling roll was maintained at 15 ℃ and pre-heated the prepared sheet at 80 ℃ for 30 seconds and then simultaneously stretched biaxially to prepare a polyamide film having a thickness of 15 ㎛.

<Examples 2-5>

Except for changing the content of the barium sulfate fine particles coated with Al ₂ O ₃ in Example 1 as shown in Table 1, a polyamide film was prepared under the same conditions and methods.

<Examples 6-8>

Except for changing the composition of the dispersant (STPP) in Example 2 as shown in Table 1, a polyamide film was prepared under the same conditions and methods.

<Examples 9-10>

Except for changing the particle diameter of the barium sulfate fine particles coated with Al ₂ O ₃ in Example 2 as shown in Table 1, a polyamide film was prepared under the same conditions and methods.

<Examples 11-13>

Except that the barium sulfate particles in Example 2 was coated with SiO ₂ in the composition of Table 1, a polyamide film was prepared under the same conditions and methods.

Comparative Example 1

Except for adding the barium sulfate fine particles not coated with an inorganic compound on the surface in Example 2, a polyamide film was prepared under the same conditions and methods.

<Comparative Example 2-4>

A polyamide film was prepared under the same conditions and methods except for adding silica fine particles as an inorganic filler in Example 2, as shown in Table 1.

The physical property evaluation method of the polyamide film prepared in the above Examples and Comparative Examples is as follows and the results are shown in Table 2.

(1) Friction coefficient

The coefficient of friction was measured in accordance with ASTM D1894 at 25 ° C. and 60% relative humidity. The length of the lower specimens (mm) was 250 × 130 and the length of the upper specimens (mm) was 65 × 60. Five measurements were made at a speed of 150 mm / min to obtain the average of the remaining values except for the maximum and minimum values.

(2) relative viscosity

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

Relative viscosity = Falling time of solution (sec) / Falling time of pure sulfuric acid (sec)

(3) haze

Measured according to ASTM D1003 and expressed as a percentage. The haze of the film was measured in the visible region using a haze meter (TOYOSEIKI, Japan).

(4) dispersibility of inorganic particles

Dispersion of the barium sulfate particles in the polymerized polyester resin was analyzed using SEM-IA, and evaluated as follows.

Excellent ← ◎> ○> △> × → Poor

division Dispersibility Haze (%) Light transmittance (%) Relative viscosity Dynamic friction coefficient Example 1 ◎ 0.4 89.1 3.38 0.53 Example 2 ◎ 0.5 88.9 3.29 0.47 Example 3 ○ 1.4 86.2 3.33 0.41 Example 4 ◎ 0.1 89.8 3.30 0.61 Example 5 ○ 2.0 85.7 3.27 0.32 Example 6 ○ 0.6 89.4 3.27 0.48 Example 7 ◎ 0.5 89.3 3.33 0.47 Example 8 △ 0.7 87.6 3.32 0.50 Example 9 △ 0.3 89.2 3.29 0.65 Example 10 △ 1.1 85.6 3.30 0.57 Example 11 ○ 0.7 88.8 3.31 0.55 Example 12 △ 1.2 87.7 3.33 0.61 Example 13 ○ 0.9 88.5 3.35 0.49 Comparative Example 1 × 3.7 75.4 3.34 0.61 Comparative Example 2 ◎ 2.1 80.4 3.28 0.56 Comparative Example 3 ◎ 2.7 77.6 3.30 0.48 Comparative Example 4 ○ 4.2 68.9 3.36 0.40

As a result of measuring the physical properties, the polyamide film of the example in which the barium sulfate fine particles coated with the inorganic compound containing aluminum or silicon was used as the inorganic filler, and the comparative example using the barium sulfate fine particles without the surface coated with the inorganic compound as the inorganic filler. Dispersibility is significantly improved than that of 1, and thus, the problem of reduced transparency due to poor dispersion can be seen to be remarkably improved.

In addition, the polyamide film prepared in the embodiment of the present invention, the comparative problems 2 to 4, that is, the problem of lowering the transparency of the polyamide film using silica fine particles as an inorganic filler significantly improved, while at the same time running and dispersibility It can be seen that it is excellent.

As described above, the present invention provides a polyamide film having excellent runability and no drop in transparency by using barium sulfate fine particles coated with an inorganic compound on the surface of the polyamide film as an inorganic filler.

In another aspect, the present invention provides a polyamide film that can contribute to the reduction in manufacturing cost and the production speed can be prevented by reducing the transparency while maintaining the runability without applying a separate active material on the film surface.

Claims (5)

Including an inorganic compound containing aluminum or silicon barium sulfate fine particles coated on the surface as an inorganic filler, The inorganic compound is used 0.5 to 10 parts by weight based on 100 parts by weight of the barium sulfate fine particles, The inorganic filler is a polyamide film having a particle size of 0.1 ~ 5.0㎛, 5-30% by weight of the fine particles having a particle size of 1㎛ or more of all the fine particles. delete delete delete The method of claim 1, Inorganic filler is 0.05 to 1 parts by weight based on 100 parts by weight of polyamide resin, polyamide film.