JP3409532B2 - Polyamide resin composition - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyamide resin composition for stretched matte films. More specifically, the present invention relates to a stretched polyamide-based matte film having a uniform and roughened surface by blending xonotlite (calcium silicate) with a polyamide resin.

[0002]

2. Description of the Related Art Conventional methods for producing a so-called matte film, in which a plastic film is roughened, include 1) a sandblasting method in which hard granular sand is blown onto the film surface, and 2) inorganic particles are applied to the film surface. 3) A method of kneading inorganic particles such as silica and titanium oxide into the film resin in advance 4) Chemical etching that corrodes the film surface with acid, alkali, solvent, etc. laws are known. In the case of roughening of a polyamide-based film, it is mainly carried out by a method of mixing silica and stretching, but there is a defect that microvoids are generated between the polyamide resin and silica during stretching, resulting in devitrification. ing. When this devitrification occurs, when the film is colored, the color does not appear vividly (for example, red becomes pink), which poses a problem.

[0003]

[Means for Solving the Problems] The present invention achieves a drastic improvement of the above drawbacks caused by using silica conventionally by using fibrous xonotlite as inorganic particles for polyamide-based matte films. It is.

[0004] That is, the present invention relates to a polyamide resin composition for stretched matte films, which is characterized by blending 0.5 to 5% by weight of fibrous xonotlite in a polyamide resin.

The fibrous xonotlite of the present invention has the molecular formula,
It is _represented by _{6CaO.6SiO2.H2O} . A predetermined amount of this is blended with a polyamide resin, and a film having a predetermined thickness is formed by an extrusion molding method, and this film can be suitably used as a film for packaging food, mainly meat, processed meat, and the like.

The general physical properties of the fibrous xonotlite of the present invention are as follows: Appearance: White granular crystal form: Acicular True specific gravity: 2.48 Bulk specific gravity: 0.2 or less Fiber length: 1-5 µm Fiber diameter: 0.1-0 .5 μm specific surface area (BET method): 20 to 40 m ² /g. Although the present invention is not limited to those having the above general physical properties, it is particularly preferable to use fibrous xonotlite having the above physical properties.

In the present invention, the amount of fibrous xonotlite added to the polyamide resin is 0.5 to 5% by weight, preferably 1.0 to 3.0% by weight. Addition amount is 0.5
%, the matte effect does not appear. Even if it exceeds 5%, the effect is not extended, the physical properties of the polyamide film are deteriorated, and the cost is increased.

Specific examples of the polyamide resin in the present invention include polylactams such as nylon 6, nylon 11 and nylon 12; polyamides obtained from dicarboxylic acids and diamines such as nylon 66, nylon 610 and nylon 612; /66, Nylon 6/6
10, nylon 6/12, nylon 6/612, nylon 6/66/610, nylon 6/66/12, nylon 6/6T (T: terephthalic acid component) and other copolymerized polyamides, and mixtures thereof. be done.

[0009] As for the method of mixing with the polyamide resin, a method of uniformly dispersing it in the raw material before polymerization and then polymerizing it, or a method of mixing or kneading with the polyamide resin can be applied. Further, a resin composition containing a high concentration of fibrous xonotlite is prepared in advance by the above method,
A method of mixing this resin composition and a polyamide resin containing no fibrous xonotlite by dry blending can also be applied.

[0010] As a method for producing a film comprising the resin composition of the present invention, a known production method can be applied. Specifically, the resin composition is melt-kneaded with an extruder,
A casting method in which a flat film is extruded using a T-die or a coat hanger die, and the film is cooled by casting on the surface of a casting roll;
Alternatively, a tubular method or the like is applied in which a cylindrically extruded product is water-cooled by a ring-shaped die.

[0011] The present invention can be accomplished by stretching the flat or tubular film, either continuously or in a separate process. For example, in the case of the sequential biaxial stretching method, a flat unstretched film is stretched 2 to 4 times with a roll type longitudinal stretching machine and then stretched 3 to 5 times with a tenter type transverse stretching machine to obtain a biaxially stretched film. After the axially stretched film is optionally heat-treated, the film can be produced by continuously winding the film while slowly cooling it.

The biaxially stretched polyamide film according to the present invention is produced by the tenter sequential biaxial stretching method as exemplified above.
It can also be produced by other methods such as a tenter type simultaneous biaxial stretching method and a tubular method.

Other additives, such as antioxidants, weathering agents including ultraviolet absorbers, antistatic agents, nucleating agents, foaming agents, coloring agents, stabilizers, coupling agents, etc., may also be added depending on the properties required. can be contained, and other inorganic particles can be used in combination.

[0014] The film made of the resin composition containing the filler described above can also be made into a laminate from other polymer films. The method of forming this laminate is not particularly limited, for example, a method of bonding a nylon film and one or more other polymer films with an adhesive,
Alternatively, a method of melt-coextrusion of a nylon resin and one or more polymer compounds constituting another polymer film through an adhesive resin from a multilayer spinneret can be applied.

[0015]

[Evaluation method] The present invention will be described in more detail below with reference to examples and comparative examples. In addition, the evaluation method of a physical property is as follows. (1) ASTM D by direct reading haze meter manufactured by Suga Test Instruments
The haze value (haze ratio) of the film was measured according to -1003. (2) Gloss ASTM D using a variable angle gloss meter manufactured by Suga Test Instruments
The glossiness of the film was measured according to -523. (3) Observation of microvoids Using a phase contrast microscope BH-2 manufactured by Olympus Optical Industry,
Microvoid formation conditions around the inorganic particles were observed from photographs of the inside of the film.

Comparative Examples 1 to 2, Examples 1 to 3 Commercially available nylon 6/66 copolymer resin (UBE NYLON 5033B manufactured by Ube Industries, Ltd.) is conventionally used as a base resin. Silica (Silysia 35 manufactured by Fuji Silysia Chemical Co., Ltd.) is used as a known inorganic particle.
0) was blended at 2% (Comparative Example 1), and zeolite (Silton AMT manufactured by Mizusawa Chemical Industry Co., Ltd.) was blended at 2% (Comparative Example 2), and fibers as the inorganic particles of the present invention were added to the base resin. Master pellets containing xonotlite at a concentration of 7% were mixed in amounts of 1.5% each.
Predetermined amounts were dry-blended to 0, 2.0, and 3.0% by weight (Examples 1 to 3).

Films were produced from these five types of pellets using the following molding machine and molding conditions, and their physical properties were evaluated. Table 1 shows the evaluation results of physical properties. a) Molding machine: 40 mmφE manufactured by Plastic Engineering Laboratory
x, T-die film forming machine b) Film thickness: 110 μm _c ) Molding conditions Cylinder Adapter Die C1 C2 C3 _C4 AD D Set temperature 230°C ₂₄₀ ° _C 250°C 250°C 250°C 250°C Roll temperature 42°C Above All of the 5 types of pellets had stable film formability, and no troubles were observed. Thickness: Using a film of 110 µm, a biaxially stretched film was formed under the following conditions. Molding machine: Biaxial stretching machine manufactured by Iwamoto Seisakusho Stretching ratio: 2.4 times longitudinally, 2.4 times transversely, total 5.8 times by simultaneous stretching Stretching temperature: 70°C Film thickness: 20 µm

A composite film was produced by laminating the above biaxially oriented polyamide film and a red-colored polyethylene film using an adhesive for dry lamination. Table 1 shows the results of visual observation 1 of the coloring state of this composite film.

[0019]

[Table 1]

Claims (1)

(57) [Claims] 1. A polyamide resin composition for a stretched matte film, comprising a polyamide resin and 0.5 to 5% by weight of fibrous xonotlite.