JP2012158031A - Polyamide based double-layer matte film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyamide based double-layer matte film which has a high haze and sophistication with a surface in lusterless state and a feel of Japanese paper.SOLUTION: This is a polyamide based double-layer matte film that is a film on which a matte layer (B layer) is laminated on one surface of a base material layer (A layer) formed from a polyamide resin, and is characterized by being comprised of a resin which B layer is a principal ingredient of polyamide resin and a fine silica powder which oil absorption measured by JIS K5101 is less than 220 ml/100 g, and a film haze is more than 40% and a surface glossiness of the B layer is less 20%.

Description

  The present invention relates to a laminated film formed of a polyamide-based resin, and more specifically, a polyamide-based mat-like multi-layer suitable for packaging applications exhibiting a high-class feeling due to an excellent matte tone and good mechanical properties. Related to film.

  Polyamide-based resin films have good mechanical properties, thermal properties, and transparency, and are therefore widely used for packaging applications, particularly food packaging applications. In recent years, as one application among the diversification of applications, a matte-like film in which fine irregularities are provided on the film surface to form a ground glass has been demanded in order to improve design properties. By using such a matte tone, the gloss of the film surface is eliminated (matte), the content is blurred, and further, a Japanese paper texture is imparted, whereby a high-quality packaging can be obtained. As one of means for imparting a matte tone to the film, a method of incorporating inorganic particles, organic synthetic resin, or the like in the resin constituting the film can be cited (for example, Patent Documents 1 and 2).

  Patent Document 1 describes a method of matting the surface of a film by adding a certain amount of specific silicon dioxide. This is a means of forming minute protrusions on the surface of the film to diffusely reflect light. However, since the film described in Patent Document 1 has a single-layer structure, voids due to silicon dioxide are likely to be generated inside the film, leading to deterioration of mechanical properties such as bending resistance.

  Patent Document 2 describes that a matte tone is imparted to a film by providing a mixed layer containing a polyamide resin having a specific viscosity difference. However, although the film obtained by this method has a good haze value, it has a high glossiness due to lack of matting effect on the surface, and does not become a film with a high-grade feeling like a Japanese paper texture.

Japanese Patent Laid-Open No. 11-279401 JP 2008-173875 A

  The present invention provides a high-quality polyamide mat-like multilayer film having excellent mechanical properties, high haze, a matte surface, and a Japanese paper texture.

Therefore, as a result of intensive studies, the present inventors have found that a high-quality mat can be obtained without impairing the mechanical properties of the film by providing a layer to which specific fine-powder silica is added on one side of the polyamide-based resin base layer. It was found that the tone can be given.
The gist of the present invention is as follows.
(1) A film in which a mat layer (B layer) is laminated on one side of a base material layer (A layer) made of a polyamide-based resin, and the B layer is a resin mainly composed of a polyamide-based resin and JIS K5101. A polyamide-based mat comprising a finely divided silica having an oil absorption of 220 ml / 100 g or less, a haze of the film of 40% or more, and a surface gloss of the B layer of 20% or less. Layer film.
(2) Mass ratio of polyamide resin and fine powder silica in layer B is 98.0 / 2.0 to 95.0 / 5.0 Layer film.
(3) The polyamide-based mat-like multilayer film according to (1) or (2), wherein the B layer has a thickness of 3 μm or more and is ½ or less of the multilayer film thickness.
(4) The polyamide mat-like multilayer film according to any one of (1) to (3), wherein the fine particle silica of the B layer has an average particle size of 2.0 to 5.0 μm.

  According to the present invention, there is provided a high-grade polyamide mat-like multilayer film having excellent mechanical properties, high haze, a matte surface, and a Japanese paper texture, which is suitable for packaging applications and the like. Can be used for

  Hereinafter, the present invention will be described in detail.

  The film of the present invention is a multilayer film having a base material layer (A layer) and a mat layer (B layer).

  In the present invention, the polyamide-based resin used for the A layer and the B layer is generally a polymer having an amide group in the molecular chain, and representative examples thereof include 6-nylon, 6,6-nylon, 6,10. -Nylon, 11-nylon, 12-nylon, poly (metaxylene adipamide), etc. are mentioned. The polyamide may be a mixture of the above-mentioned polyamides, such as 6-nylon / 6,6-nylon, 6-nylon / 6,10 nylon, 6-nylon / 12-nylon, 6-nylon / 6,10. -It may be a copolymer of two or more such as nylon / 12-nylon, or may be a mixture of these. Among the above, 6-nylon is preferred because it is most readily available and has high versatility. In addition, as a polyamide-type resin which comprises A layer, aromatic polyamide like poly (metaxylene adipamide) can also be used from the point of stretchability and an oxygen barrier.

  The relative viscosity that serves as an index of the molecular weight of the polyamide-based resin is preferably in the range of 1.5 to 5.0, more preferably in the range of 2.5 to 4.0 from the viewpoint of mechanical properties. Here, the relative viscosity is a value measured in 96% by mass sulfuric acid at a concentration of 1 g / dl and a temperature of 25 ° C.

  The finely divided silica used in the B layer needs to have an oil absorption of 220 ml / 100 g or less, preferably 200 ml / 100 g or less, measured according to JIS K5101. If the oil absorption exceeds 220 ml / 100 g, the dispersibility of fine powder silica in the polyamide resin is deteriorated, and the haze and gloss are inferior.

  The method for forming finely divided silica is not particularly limited, but generally, a method of pulverizing and classifying synthetic silica is employed, but a method of directly forming spherical fine particles at the time of synthesis can also be employed.

  The mass ratio of the polyamide-based resin and the finely divided silica in the B layer is preferably 98.0 / 2.0 to 95.0 / 5.0. When the mass ratio is less than 95.0 / 5.0, mechanical properties due to the generation of fish eyes and voids tend to be lowered. On the other hand, if it exceeds 98.0 / 2.0, the formation of protrusions on the film surface becomes insufficient, and the matte effect may not be obtained.

  The average particle diameter of the fine powder silica used for the B layer is preferably in the range of 2.0 μm to 5.0 μm. If it is smaller than 2.0 μm, it becomes difficult to form protrusions on the film surface. If it exceeds 5.0 μm, it may cause voids in the resin and decrease in mechanical properties.

  In the B layer, addition of finely divided silica to the polyamide resin can be performed at any stage of the production. For example, a method of internally adding before or after the start of polymerization of the polyamide resin, a method of melt-kneading the polyamide resin and silica in an extruder, and a method of dry blending the polyamide resin and silica are included.

  In the A layer, an anti-bending pinhole property improving agent such as polyolefins, polyamide elastomers, polyester elastomers and the like can be added. A plurality of these may be used in combination.

  In the layer A, one or two kinds of various additives such as pigments, antioxidants, ultraviolet absorbers, preservatives, antistatic agents, inorganic fine particles and the like are included as long as the effects of the present invention are not impaired. The above may be added.

  In order to improve the anti-blocking property on the surface of the layer A, one or more inorganic lubricants and organic lubricants may be blended. These lubricants include clay, talc, mica, calcium carbonate, zinc carbonate, wollastonite, silica, alumina, magnesium oxide, calcium silicate, sodium aluminate, calcium aluminate, magnesium aluminosilicate, glass balloon, zinc oxide, Antimony trioxide, zeolite, kaolinite, hydrotalcite, layered silicate, stearic acid amide, behenic acid amide, erucic acid amide, ethylene bis stearic acid amide, phenol resin, melamine resin, polymethyl methacrylate resin, etc. .

  The total thickness of the polyamide mat-like multilayer film of the present invention is not particularly limited, but is preferably 6 to 25 μm, and more preferably 12 to 25 μm. When the thickness is less than 6 μm, the toughness characteristic of the polyamide film may not be sufficiently exhibited. When it exceeds 25 μm, the film becomes hard and the mass becomes heavy.

  In the present invention, the thickness of the B layer is preferably 3 μm or more and less than ½ of the multilayer film thickness. If the thickness of the B layer is less than 3 μm, a sufficient matte tone cannot be obtained in terms of haze and gloss on the surface of the B layer. When the thickness of the B layer exceeds 1/2 of the multilayer film, the mechanical properties of the film deteriorate.

  In the present invention, the glossiness of the B layer needs to be 20% or less, preferably 15% or less. When the glossiness exceeds 20%, the matte tone is insufficient and the desired Japanese paper texture cannot be obtained.

  In the present invention, the haze of the film surface needs to be 40% or more. If it is less than 40%, a Japanese paper texture cannot be obtained.

  The polyamide mat-like multi-layer film of the present invention is preferably used by laminating and laminating a sealant layer on the A layer side. The laminating method can be performed by a method usually used for polyamide films, such as dry lamination and extrusion lamination.

  The production method of the polyamide-based mat-like multilayer film of the present invention is not particularly limited, and a known method can be used. Among them, by extruding a resin to obtain an unstretched film and biaxially stretching it. The resulting method is preferred.

  Next, the present invention will be specifically described with reference to examples. In addition, the evaluation method of the various physical properties in an Example and a comparative example is as follows.

(1) Oil absorption:
It measured according to JIS-K5101.
(2) Haze (%):
Using a Nippon Denshoku haze meter (NDH 2000), total light transmittance (Tt) and diffuse transmittance (Td) were measured according to JIS K 7105, and haze was calculated based on the following formula.
Haze (%) = (Td / Tt) × 100

(3) Glossiness (%)
The surface of the film was measured at an incident angle of 20 ° in accordance with JIS K 7105 using a Murakami Color Research Laboratory (GROSS METER GM-26 PRO).

(4) Average particle diameter It measured with the laser diffraction type particle size distribution measuring apparatus (SALD-2200, Shimadzu Corporation make).

[Polyamide resin]
As the polyamide-based resin, nylon 6 resin (A1030BRF manufactured by Unitika Ltd., melting point 220 ° C., relative viscosity 3.1) was used.

[silica]
Silica-1: average particle size 2.7 μm, oil absorption 170 ml / 100 g.
Silica-2: Average particle size 4.1 μm, oil absorption 220 ml / 100 g.
Silica-3: average particle size 3.9 μm, oil absorption 310 ml / 100 g.

[Example 1]
<Manufacture of kneaded resin forming B layer>
Using a PCM-30 manufactured by Ikegai Seisakusho, a blend of A1030BRF / silica-1 (mass ratio) = 97.5 / 2.5 was charged from the supply port, cylinder temperature 230 ° C. to 270 ° C., screw rotation speed 200 rpm, discharge amount Melt kneading was performed under the condition of 10 kg / hr. The obtained kneaded product was extruded with strands, cut with a pelletizer to form polyamide pellets containing silica, and further vacuum dried (80 ° C., 24 hours).
<Manufacture of multi-layer stretched film>
Next, the kneading resin for forming the B layer is melted by an extruder and supplied to the T die, and the resin A1030BRF to be the A layer is melted by another extruder and supplied to the T die. The sheet is discharged while being laminated, wound around a metal drum adjusted to 20 ° C., cooled and wound up to have a two-layer structure of B layer (mat layer) and A layer (base material layer). A laminated film (unstretched film) having a thickness of 150 μm was produced. The end of this unstretched film is held by a clip of a tenter type simultaneous biaxial stretching apparatus, and simultaneously biaxial at a stretching ratio of 3.0 times in the MD direction and 3.3 times in the TD direction under the condition of 180 ° C. After stretching, the heat treatment was performed at 210 ° C. for 4 seconds with a relaxation rate in the TD direction of 5%, gradually cooled to room temperature, and the thickness was B layer / A layer = 5.0 / 10.0 (μm). A polyamide-based mat-like multilayer film was obtained. The evaluation results of physical properties are shown in Table 1.

[Example 2 and Comparative Example 2]
A polyamide-based matte multilayer film was obtained in the same manner as in Example 1 except that the mass ratio of A1030BRF / silica-1 in the B layer was changed to the ratio shown in Table 1. The evaluation results of physical properties are shown in Table 1.

[Example 3]
A polyamide-based mat-like multilayer film was obtained in the same manner as in Example 1 except that the silica type of the B layer was changed to the type shown in Table 1. The evaluation results of physical properties are shown in Table 1.

[Example 4]
A polyamide mat-like multilayer film was obtained in the same manner as in Example 3 except that the thickness configuration of the B layer / A layer was changed to the configuration shown in Table 1. The evaluation results of physical properties are shown in Table 1.

[Comparative Example 1]
A polyamide-based mat-type multilayer film was obtained in the same manner as in Example 1 except that the type of silica in layer B and the weight ratio of A1030BRF / silica were changed as shown in Table 1. The evaluation results of physical properties are shown in Table 1.

[Comparative Example 3]
A polyamide-based mat-type multilayer film was obtained in the same manner as in Example 1 except that the thickness configuration of the B layer / A layer was changed to the configuration shown in Table 1. The evaluation results of physical properties are shown in Table 1.

Claims (4)

A film in which a mat layer (B layer) is laminated on one side of a base material layer (A layer) made of a polyamide resin, and the B layer is measured according to JIS K5101 and a resin mainly composed of a polyamide resin. A polyamide-based mat-type multi-layer film comprising finely divided silica having an oil absorption of 220 ml / 100 g or less, a haze of the film of 40% or more, and a surface glossiness of the B layer of 20% or less. The polyamide mat-like multi-layer film according to claim 1, wherein the mass ratio of the polyamide-based resin and the fine powder silica in the B layer is 98.0 / 2.0 to 95.0 / 5.0. The polyamide mat-like multilayer film according to claim 1 or 2, wherein the B layer has a thickness of 3 µm or more and 1/2 or less of the multilayer film thickness. 4. The polyamide mat-like multi-layer film according to any one of claims 1 to 3, wherein the fine particle silica of the B layer has an average particle size of 2.0 to 5.0 [mu] m.