JPH04220436A - Polyolefin film - Google Patents

Abstract

PURPOSE:To provide a polyolefin film which is excellent in blocking resistance and slip properties and is hardly marred up by the friction between the films. CONSTITUTION:A polyolefin film which contains silicone rubber particles having a mean diameter of 0.5-3mum and a rubber hardness A of 30-80 degrees; and a laminate film which comprises the polyolefin film laminated with a polyolefin layer having a higher m.p. than that of the polyolefin film.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyolefin film that has excellent blocking resistance and is resistant to scratches on its surface.

0002

BACKGROUND OF THE INVENTION The blocking resistance of polyolefin films has conventionally been improved by incorporating small amounts of silica into polyolefins. Although this method improves blocking resistance, when a polyolefin film containing this silica is used in an automatic packaging machine, there is a problem that packaging defects frequently occur due to the insufficient slipperiness of the polyolefin film. there were.

[0003] In order to solve the above problems, recently silicone resins have been used in place of silica (Japanese Patent Laid-Open No. 62-215646, Japanese Patent Laid-open No. 62-232448).
(Japanese Patent Application Laid-open No. 62-233248). By incorporating the silicone resin, a polyolefin film with improved slip properties and excellent blocking resistance equivalent to or better than that of silica was obtained.

0004

[Problems to be Solved by the Invention] However, polyolefin films containing silicone resin are prone to scratches on the surface due to rubbing between the films, and the transparency of the film deteriorates due to the scratches on the surface, reducing the commercial value. There was a problem.

[0005] An object of the present invention is to provide a polyolefin film that has excellent anti-blocking properties and slip properties, and is resistant to scratches caused by rubbing between the films.

[0006]

[Means for Solving the Problem] As a result of repeated experiments in order to achieve the above object, the present inventors have found that by blending silicone rubber particles having a specific particle size and elasticity into a polyolefin film, the above object can be achieved. The inventors have discovered that the object can be achieved, and have proposed the present invention.

That is, in the present invention, the average particle diameter is 0.5 to 3.
It is a polyolefin film containing 0.05 to 1% by weight of silicone rubber particles having a rubber hardness A of 30 to 80 degrees.

In the present invention, the silicone rubber particles dispersed and blended into the polyolefin film have an average particle diameter of 0.5 to 3 μm and a rubber hardness A of 30 to 80 degrees. The average particle size should be in the range 0.5-3 μm, preferably in the range 1-2 μm. When the average particle diameter of the silicone rubber particles is less than 0.5 μm, the effect of improving blocking resistance and sliding property is poor;
On the other hand, if it exceeds 3 μm, the transparency of the film will deteriorate and the height of the protrusions caused by silicone rubber particles protruding from the film surface will increase, causing ink to fall out due to the protrusions in gravure printing etc., impairing the aesthetic appearance. cormorant. Further, the rubber hardness A of the silicone rubber particles must be 30 to 80 degrees, preferably in the range of 35 to 75 degrees. When the rubber hardness A is less than 30 degrees, the effect of improving blocking resistance and sliding property is small, and when it exceeds 80 degrees, the transparency of the polyolefin film decreases because it is easily scratched, which is not preferable. Note that the rubber hardness A in the present invention is a value measured according to JISK 6301.

[0009] The shape of the silicone rubber particles is not particularly limited, but from the viewpoint of improving blocking resistance and sliding properties, spherical shapes are preferred. Since commercially available silicone rubber particles are usually spherical, commercially available particles may be used as they are.

The amount of silicone rubber particles blended into the polyolefin film is 0.05 to 1% by weight, and 0.1 to 1% by weight.
Preferably it is 0.5% by weight. When the blending amount of silicone rubber particles is less than 0.05% by weight, the effect of improving blocking resistance and slipperiness is poor, and when the blending amount exceeds 1% by weight, transparency deteriorates.

The polyolefin in the present invention is a homopolymer of α-olefins such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, or a copolymer of the above α-olefins. Copolymers of α-olefins and monomers other than α-olefins that are copolymerizable with the above α-olefins, mixtures thereof, and the like may be employed without any limitation. Monomers other than α-olefins that can be copolymerized with the above α-olefins include:
Examples include vinyl acetate and maleic acid.

The present invention is particularly effective for polyolefins whose surfaces are easily scratched among the above-mentioned polyolefins. Specific examples of such polyolefins include polyethylene, ethylene-propylene copolymer (ethylene content 2 to 5 mol%), ethylene-vinyl acetate copolymer, ethylene-1-butene copolymer, ethylene-propylene-
Examples include 1-butene copolymer, ethylene-propylene-butadiene copolymer, and blends containing these polyolefins as main components.

[0013] The present invention may be a single layer film of polyolefin, and the above-mentioned layer of polyolefin (A), which is easily scratched on the surface, and polyolefin (B), which has a higher melting point than the polyolefin (A), may be used. It may also be an easily heat-sealable polyolefin film in which layers are laminated. In the case of the above laminated film, silicone rubber particles are blended into the layer of polyolefin (A). Polyolefin (A) is as mentioned above, but polyolefin (B) is generally polyolefin (A).
) has a melting point higher than that of 20°C to 70°C. Specifically, propylene homopolymer, propylene-ethylene random copolymer (ethylene content: 3 mol% or less), etc. can be mentioned.

In order to obtain a laminated polyolefin film with good heat sealability, 60 to 90 parts by weight of a propylene-ethylene random copolymer (ethylene content 2 to 5 mol%) and 1-butene are used as the polyolefin (A). It is preferable to use a mixture of 10 to 40 polymerized parts of the homopolymer, and use a propylene homopolymer or a propylene-ethylene random copolymer (ethylene content: 0.5 mol % or less) as the polyolefin (B).

[0015] In order to prevent the surface from being scratched, the polyolefin (A) layer preferably has a thickness approximately equal to the diameter of the silicone rubber particles, and is usually 0.5 mm thick.
It is selected from the range of ~3 μm. In addition, polyolefin (
The layer B) generally has a thickness of 10 to 60 from the viewpoint of film strength.
Selected from the μm range.

Furthermore, it is optional to further laminate a layer of polyolefin (A) to the layer of polyolefin (B) of the laminated polyolefin film described above to form a sandwich structure, or to laminate a layer of another polyolefin. can be done.

The polyolefin film of the present invention can be produced by sufficiently mixing polyolefin powder or pellets with silicone rubber particles and then melt-extruding the mixture or further uniaxially or biaxially stretching the mixture. In the case of a laminated film, the polyolefins constituting each layer are coextruded and then stretched uniaxially or biaxially as necessary, or one layer of polyolefin is melt extruded and uniaxially stretched, and then the other layer is placed on top of it. A method is employed in which polyolefin is melt extruded and stretched in a direction substantially perpendicular to the direction of the uniaxial stretching.

[0018]

[Effect] The polyolefin film of the present invention has excellent anti-blocking properties and slip properties, so it can be used for packaging with automatic packaging machines.Furthermore, the polyolefin film of the present invention has excellent anti-blocking properties and slip properties, so it can be used for packaging with automatic packaging machines. can suppress the decline in Therefore, the polyolefin film of the present invention can be suitably used as various packaging materials for foods, cigarettes, cassette tapes, video tapes, floppy disks, and the like.

[0019]

[Examples] Examples and comparative examples are listed below to specifically explain the present invention, but the present invention is not limited to these examples. In addition, the physical properties of the films in the following Examples and Comparative Examples were measured by the following methods.

(1) Scratch resistance Prepare two films, one film (20×3
0 cm) was fixed as the lower film, the other film was used as the upper film, a 4.6 kg weight was placed on the upper film, and it was brought into contact with the lower film in an area of 10 x 10 cm, and the upper film was moved horizontally.
The area was rubbed back and forth twice. The haze before and after the above operation was measured according to JIS K 6714.

(2) After producing the slip film, after curing at 40°C for 3 days, ASTM-D
It was measured in accordance with the static friction coefficient measurement method of 1894.

(3) Blocking property Two films (120 x 120 mm) are overlapped,
Load 10kg (69.4g/cm2), temperature 40℃,
After being left in an atmosphere with humidity of 90% RH for 24 hours, 40 x 40
Cut the sample into mm and test it with a tensile tester (speed: 10
The shear peel strength was measured at 0 mm/min).

(4) Heat-sealability Using a 5 x 200 mm heat-sealing bar, 15 m from the sample was sealed under the conditions of heat-sealing pressure of 1 kg/cm2 and heat-sealing time of 1.0 seconds at each set temperature.
A sample with a width of m was cut out and measured using a tensile tester at a tensile speed of 100 mm/min. The results were taken as the average value of 5 samples.

In the above (1) to (4), various measurements were carried out with the layers containing silicone rubber particles facing each other in the examples and the layers containing various particles facing each other in the comparative examples. In addition, slipping and blocking properties were exhibited when the surface of the layer containing the silicone rubber particles or various particles was subjected to corona discharge treatment (treatment density: 30 W/m 2 ·min) and when it was not, respectively.

Examples 1 to 3 Melt index: 2.0 g/10 min, crystallinity: 98.
To 100 parts by weight of 4% polypropylene (melting point 159°C), glycerin monostearate and N, as antistatic agents were added.
0.5 parts by weight of N'-bis(2-hydroxyethyl)alkylamine, 0.03 parts by weight of erucic acid amide, and 0.04 parts by weight of calcium stearate were added and melt-kneaded. It was used as a resin composition. On the other hand, a resin (melting point: 115°C) prepared by mixing 30 parts by weight of polybutene-1 with 100 parts by weight of a propylene-ethylene random copolymer having an ethylene content of 3 mol% was added to a resin with an average particle diameter of 1.
Silicone rubber spherical particles having a diameter of 8 μm and a rubber hardness A of 40 degrees were added at the blending ratio shown in Table 1 to form a resin composition for the surface layer.

Using the resin compositions for the base layer and surface layer described above, a three-layer laminate film having surface layers laminated on both sides of the base layer was obtained using a tenter biaxial stretching machine. The thickness of each layer was 1.5 μm/22 μm/1.5 μm.

The scratch resistance, slip property, blocking property and heat seal property of these films were measured and the results are shown in Table 1.

Example 4 100 parts by weight of a propylene-ethylene copolymer (melting point: 125°C) with an ethylene content of 3.5 mol % was added with an average particle size of 1.
A laminated film (thickness: The same procedure as Examples 1 to 3 was carried out except that a surface layer of 1.5 μm/base layer of 23.5 μm was obtained. The results are shown in Table 1.

Comparative Examples 1 to 3 Instead of the silicone rubber spherical particles added to the surface layer of Example 1, melamine resin spherical particles with an average particle size of 1.5 μm, non-melting silicone resin spherical particles with an average particle size of 2 μm, and The same procedure as in Example 1 was carried out except that crushed silica particles having an average particle diameter of 1.5 μm were used. Results first
Shown in the table.

[0030]

[Table 1]

Examples 5 to 7 Melt index 7.5 g/10 min, ethylene content 2
．． 5 mol% propylene-ethylene random copolymer 1
00 parts by weight mixed with 5 parts by weight of polybutene-1 (
melting point 122°C), glycerin monostearate and N,N'-bis(2-hydroxyethyl) as antistatic agents.
0.5 parts by weight of each alkylamine, 0 erucic acid amide
．． 0.03 parts by weight of calcium stearate and 0.04 parts by weight of calcium stearate were mixed. In addition, the average particle diameter is 2.5 μm, and the rubber hardness is A.
Silicone rubber spherical particles having an angle of 40 degrees were added in the proportions shown in Table 2. A single layer film was obtained from this using a cast film film forming machine. The thickness was 25 μm.

[0032] The scratch resistance, slip property and blocking property of these films were measured, and the results were compared to the second
Shown in the table.

Comparative Examples 4 to 5 In place of the silicone rubber spherical particles of Example 5, melamine resin spherical particles with an average particle diameter of 1.5 μm and melamine resin spherical particles with an average particle diameter of 2
The same procedure as in Example 5 was carried out except that non-melting silicone resin spherical particles of μm were used, and the results are shown in Table 2.

[0034]

[Table 2]

Claims (2)

[Claims] Claim 1: Silicone rubber particles having an average particle diameter of 0.5 to 3 μm and a rubber hardness A of 30 to 80 degrees are
A polyolefin film containing 5 to 1% by weight. 2. Silicone rubber particles having an average particle diameter of 0.5 to 3 μm and a rubber hardness A of 30 to 80 degrees.
A polyolefin film formed by laminating a layer of polyolefin (A) containing 5 to 1% by weight and a layer of polyolefin (B) having a higher melting point than the polyolefin (A).