JPS61120840A - Polyolefin film having antistatic properties - Google Patents

Abstract

PURPOSE:To provide a polyolefin film possessing excellent clarity and antistatic properties permanently, by incorporating a polyolefin resin with a fatty acid monoglyceride and monovalent metal salt of unsatd. fatty acids in a specific ratio. CONSTITUTION:A polyolefin film contg. a fatty acid monoglyceride and a monovalent metal salt of unsatd. fatty acids in a wt. ratio of 2-40:1, the total amt. of the components being within the range of 0.2-4wt% based on the amt. of polyolefin resin, Pref. fatty acid monoglycerides used are 12-22C satd. and unsatd. fatty acid monoglycerides, and tallow fatty acids are desirable practically. Pref. monovalent metal salts of unsatd. fatty acids are sodium oleate, potassium oleate, sodium erucate, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a polyolefin film that permanently provides excellent transparency and antistatic properties.

[Conventional technology]

Polyolefin films such as polyethylene films and stretched polypropylene films have excellent properties such as transparency, stiffness, and moisture resistance, and are widely used as packaging materials for various products. However, since the polyolefin film has electrostatic properties, it must be imparted with antistatic properties or slip properties in practical use, and is generally coated with various organic and inorganic antistatic agents and slip agents. Usually, films containing additives are used.

[Problem that the invention seeks to solve]

By the way, the above-mentioned internal additives such as antistatic agents and slip agents are naturally present on the film surface and are involved in their action. After that, they aggregate on the surface of the film over time, and this tends to cause the film to lose its whiteness. In particular, fatty acid monoglyceride, which is widely used as an antistatic agent for synthetic resin products made of polyolefin resins such as polyethylene, polypropylene, and ethylene O-vinyl acetate, is an internal additive with excellent safety and antistatic properties. However, this internal additive has poor compatibility with the polyolefin resin, and has the disadvantage that the whitening phenomenon due to aggregation described above cannot be avoided.

However, when using the fatty acid monoglyceride as an internal additive, methods to prevent the whitening phenomenon due to aggregation include reducing the addition rate of the internal additive, or adding a liquid component that dissolves the fatty acid monoglyceride together with the fatty acid monoglyceride. Although several methods have been tried, the former method does not provide sufficient antistatic performance, and the latter method results in poor slipperiness, so no product has been found to be sufficiently effective from a comprehensive standpoint. is the reality.

[Means for solving problems]

The present invention consists of a polyolefin film to which fatty acid monoglyceride or fatty acid monoglyceride and other antistatic agents are internally added as an antistatic agent. By using it as an additive, it does not reduce the antistatic performance obtained and also reduces the slipperiness, and the fatty acid monoglyceride may aggregate on the film surface over time and cause the film to whiten. It has been possible to provide a polyolefin film that has a novel antistatic property.

That is, in the polyolefin film of the present invention, the fatty acid monoglyceride (a) and the monovalent metal salt of unsaturated fatty acid (b) are present in a ratio of 2 to 14-OWL (weight ratio), and the total amount of both is is 02 to 4% by weight of the polyolefin resin that is the resin component constituting the film.
It is contained within the range of

In the polyolefin film containing the fatty acid monoglyceride (a) and the monovalent metal salt of unsaturated fatty acid (b) as essential internal additives, the fatty acid monoglyceride (a)
) and monovalent metal salt of unsaturated fatty acid (b) is a small amount less than 0.2% by weight of the polyolefin resin, the resulting film will not have sufficient antistatic properties, and If the amount exceeds ヰwt%,
Not only is it not possible to obtain any special effect by adding a large amount of these internal additives, but there is also a tendency for the disadvantage that formability during film forming to deteriorate.

Furthermore, fatty acid monoglyceride (a) is one of the unsaturated fatty acids.
When the amount exceeds I+O times the amount of the valent metal salt (b), fatty acid monoglyceride (
It becomes difficult to prevent a) from coagulating on the film surface and whitening the film, and if the fatty acid monoglyceride (a) is less than twice the monovalent metal salt of unsaturated fatty acid (b), the film The antistatic property imparted to the product becomes insufficient.

Therefore, in the polyolefin film of the present invention, the total amount of the fatty acid monoglyceride (a) and the monovalent metal salt of an unsaturated fatty acid (b) is in the range of 0.2 to 5% by weight of the polyolefin resin constituting the film. , and fatty acid monoglyceride (a): monovalent metal salt of unsaturated fatty acid (b)
) is required to be contained in a ratio of 2 to 14 O:1.

When producing the polyolefin film of the present invention containing both the fatty acid monoglyceride (a) and the monovalent metal salt of unsaturated fatty acid (-b) as essential internal components, in the film forming raw material, Fatty acid monoglycerides (
A premixed mixture of a) and the monovalent metal salt of unsaturated fatty acid (b) may be added, or both may be added separately.

The polyolefin film having antistatic properties of the present invention contains both fatty acid monoglyceride (a) and monovalent metal salt of unsaturated fatty acid (b3) as essential components. Of course, in the polyolefin film of the present invention, internal additives other than the above-mentioned two components may be optionally added in combination or internally as long as the intended effects of the present invention are not inhibited. For example, antistatic agents such as N,N-dihydrogysigotylalkylamine, its fatty acid ester amide, and alkyl betaine, as well as fillers, lubricants, and other modifiers may be added as necessary. It can be added internally in combination with additives.

Furthermore, the polyolefin film having antistatic properties of the present invention may be a stretched film or an unstretched film, and may be a single layer film or a composite film. In particular, in composite films, the highest
It is sufficient that at least one of the two layers and the bottom layer is composed of a polyolefin film having the structure described in claim 1 above.

In the polyolefin film having antistatic properties of the present invention having the above structure, the polyolefin resin constituting the film may be, for example, low density polyethylene, linear low density polyethylene, high density polyethylene,
Monoolefins and monoolefins such as monoolefin polymers such as polypropylene and polybutene-1, mixtures of cholera monoolefin polymers, monoolefin copolymers and mixtures thereof, ethylene-vinyl acetate copolymers, ionomers, etc. Copolymers of monoolefins and diolefins, diolefin polymers such as polycitadiene, copolymers of monoolefins and diolefins, and the like are used.

In addition, fatty acid monoglyceride (a), which is an essential internal additive, has 12 to 2 carbon atoms from the viewpoint of antistatic performance and lubricity.
Preferred are monoglycerides of saturated fatty acids and monoglycerides of unsaturated fatty acids of No. 2, and practically preferred are monoglycerides of beef tallow fatty acids, ie C16 or C18 saturated fatty acids, and mixtures thereof.

Furthermore, the monovalent metal salt of unsaturated fatty acid (b), which is another essential internal additive, has the function of preventing fatty acid monoglyceride from aggregating and solidifying over time on the film surface, that is, whitening caused by fatty acid monoglyceride. Sodium oleate, potassium oleate, sodium erucate, potassium erucate, etc. are preferred in terms of the effect of preventing electrification, antistatic performance, lubricity, film formability, and stability of the unsaturated fatty acid. It is.

〔Example〕

Below, the specific structure of the polyolefin film having antistatic properties of the present invention will be explained using production examples, and the physical properties of the obtained film will be explained in comparison with the physical properties of the film obtained in comparative examples. do.

Example 1. Comparative Examples 1-2 A polypropylene resin compound containing the internal additives listed in the designated columns of Example 1 and Comparative Examples 1-20 in Table 1 below was extruded from a T-die to obtain a polypropylene sheet. After that, the sheet was stretched 5 times in the longitudinal direction to obtain a uniaxially stretched polypropylene film having a thickness of about 180 μm.

Next, about 20μ of an ethylene-propylene-butene copolymer resin containing 600ppm of inorganic silica was applied to one surface of the uniaxially stretched polypropylene film obtained above.
After extrusion and lamination to a thickness of , this laminated film was stretched approximately 8 times in the direction perpendicular to the stretching direction of the -axially stretched polypropylene film.

After that, the □ front of each of the obtained laminated films,
The back screen was treated with corona discharge so that the wet tension of the ethylene-propylene-butene copolymer resin layer was 32 dynes and the wet tension of the polypropylene film layer was 14-0 dynes, and the book was approximately 25 tons thick. Composite films were obtained as examples of the invention and comparative examples.

The physical properties of each composite film obtained are shown in Table 1. Example 2. Comparative Examples 3 to L+ Example 2 and Comparative Examples 3 to L1 in Table 1 below. A polypropylene-polyethylene copolymer resin blend containing the internal additives listed in the specified column is extruded from a T-die to obtain a sheet, and then the sheet is stretched 5 times in the longitudinal direction, A uniaxially stretched polypropylene-polyethylene copolymer film having a thickness of about 200 μm was obtained.

Then, the -axially oriented polypropylene-polyx-chi L/
After stretching the biaxially stretched film by 8 times in the direction perpendicular to the stretching direction of the film, one side of the obtained biaxially stretched film was subjected to corona discharge treatment so that the wetting tension on that side was 1 + O 2. A biaxially stretched film having a thickness of 25 μm and serving as an example product of the present invention and a comparative example product was obtained.

Table 1 shows the physical properties of each of the obtained biaxially oriented polypropylene-polyethylene copolymer films.

The physical properties in Table 1 are as follows.

(1) Haze (%) Value measured with a digital haze meter T NDn-2oDCH manufactured by Hondenshoku Kogyo Co., Ltd. in accordance with JISJ (6711+-).

(2) △Haze (%) Let A be the haze value measured by the method in (1) above, and reduce the haze value measured after washing and removing the surface slag of the sample with acetone. value.

(3) Charge attenuation rate (%) (antistatic property) Measured using a static honest meter (manufactured by Otsuki Shokai Co., Ltd.) according to Honshu Paper Co., Ltd.'s internal standard method. K.V.

C is the amount of charge when electricity is applied for one minute, and C is the amount of charge remaining after 30 seconds. Therefore, the higher this value is, the more antistatic it is (1ヰ). It has excellent properties when it is produced.

(4) Coefficient of Friction A value obtained by measuring the coefficient of static friction and the coefficient of dynamic friction on both the front and back surfaces of the film in accordance with ASTM D 1114-(Method B).

[Action and effect]

In the polyolefin film of the present invention, a monovalent metal salt of an unsaturated fatty acid is added to the fatty acid monoglyceride to prevent the phenomenon that the fatty acid monoglyceride internally added to the film aggregates on the film surface over time and causes the film to whiten. It is suppressed by coexisting and internally added, and has the effect of permanently maintaining the transparency of the film.

Furthermore, in the polyolefin film of the present invention,
The phenomenon in which fatty acid monoglycerides aggregate on the film surface over time is suppressed, i.e.,
Fatty acid monoglyceride (↑5) In other words, since a continuous film of fatty acid monoglyceride permanently exists on the film surface, the antistatic performance imparted to the film does not deteriorate over time, and it is a permanent film. It also has the effect of maintaining good antistatic performance.

Claims (2)

[Claims] (1) Fatty acid monoglyceride (a) and unsaturated fatty acid 1
and the valent metal salt (b) in a ratio of 2 to 40:1 (weight ratio), and the total amount of both is within the range of 0.2 to 4% by weight of the polyolefin resin. A polyolefin film with antistatic properties characterized by: (2) The monovalent metal salt of unsaturated fatty acid (b) is at least one selected from sodium oleate, potassium oleate, sodium erucate, and potassium erucate, according to claim 1 A polyolefin film with antistatic properties.