JPS5946263B2 - Polyolefin composition for anti-fog film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a polyolefin composition for film having antifogging properties.

Specifically, the present invention relates to a polyolefin composition for antifogging films that is characterized by a novel combination of additives. Conventionally, polyolefins have been used in a wide range of applications, and among them, polyolefins in the form of films or sheets are often used as agricultural sheets, films for packaging vegetables, meat, etc. However, since the surface of these polyolefin films and polyolefin sheets (hereinafter collectively referred to as polyolefin films) is almost completely hydrophobic, when water adheres to the surface, the surface will not be uniformly wetted. There is a drawback that the surface becomes cloudy because it becomes minute water droplets. In order to compensate for these drawbacks, a number of studies have been carried out in the past, and one of the most suitable is to add fatty acid esters of sorbitan such as sorbitan monostearate to polyolefins.

However, polyolefin films to which a fatty acid ester of zorbitan is added alone cannot be said to have sufficient antifogging properties. As a result of intensive research aimed at obtaining a polyolefin composition for antifogging films that does not have the above-mentioned drawbacks, the present inventors discovered that it is sufficient to incorporate a specific compound into the polyolefin together with the fatty acid ester of zorbitan. , arrived at the present invention.

That is, the gist of the present invention resides in a polyolefin composition for an antifogging film, which is characterized by containing a fatty acid ester of zorbitan and a fatty acid salt of a Group I metal of the periodic table. The present invention will be explained in detail below.

Any known fatty acid ester of zorbitan can be used as a component of the composition of the present invention.

Fatty acids can be saturated or unsaturated and usually have 12 to 2 carbon atoms.
Preferably, it is fatty acid No. 2. Among these, it is preferable to use sorbitan monofatty acid ester or norbitane difatty acid ester. Trifatty acid ester or higher fatty acid ester of zorbitan is not sufficient in terms of antifogging properties. Specifically, for example, sorbitan monostearate (HLB5, l), sorbitan monopalmitate (HLB6.7), sorbitan monooleate (HLB
B5.1), zorbitan monolaurate (HLB8,
O), sorbitane distearate (HLB4.4), sorbitane dipalmitate, sorbitane dioleate (H
LB4.5), sorbimen dilaurate (HLB6),
Examples include sorbitan sesquioleate (HLB4.8).

Of course, two or more of these fatty acid esters of zorbitan may be used in combination.

The fatty acid ester of zorbitan preferably has an HLB value of 3 to 9.

Zorbitan fatty acid esters with HLB values outside the above range do not provide sufficient antifogging properties. Any known fatty acid salts of Group metals of the periodic table, which are components of the composition of the present invention, can be used.

Fatty acids can be saturated or unsaturated and usually have 12 to 2 carbon atoms.
2 fatty acids are used. Examples of group metals of the periodic table include calcium, strontium, barium, zinc, and cadmium. Among these metals, the use of zinc has the greatest effect. Specifically, zinc stearate, zinc palmitate, zinc oleate, zinc laurate, zinc behenate, zinc linoleate,
Zinc ricinoleate, calcium stearate, calcium palmitate, calcium oleate, calcium laurate, calcium behenate, calcium linoleate, calcium ricinoleate, strontium stearate, strontium palmitate, strontium oleate, strontium laurate, barium stearate, palmitin Barium acid, barium oleate, barium laurate, cadmium stearate, cadmium palmitate, etc. can be used. Any known polyolefin can be used as a component of the composition of the present invention.

Usually, a polyolefin obtained by polymerizing an α-olefin having 2 to 8 carbon atoms is used. Specifically, polyethylene polymerized by a high-pressure method, polyethylene polymerized by a medium-low pressure method, polypropylene, polybutene, polyisobutene, etc. can be mentioned. These polyolefins may be copolymers, such as ethylene and propylene, butene, isobutene, styrene,
Mention may be made of copolymers such as acrylic acid, acrylic esters or vinyl acetate; in the case of copolymers,
It is preferred that the copolymerized monomer accounts for 20% by weight or less of the main polymerized monomer. A copolymer containing a large amount of copolymerizable monomers is difficult to form into a film. Among these polyolefins, the greatest effect is observed when polyethylene or a copolymer containing ethylene as a main component is used. In particular, polymerization with a density of 0.
The effect is great when low density polyethylene of 94 or less or ethylene monovinyl acetate copolymer is used. In the composition of the present invention, the fatty acid ester of zorbitan is usually 0.01 to 2% by weight, preferably 0.0% by weight, based on the polyolefin.
The content is 3 to 1.5% by weight.

If the amount of the fatty acid ester of zorbitan is less than the above range, there is no substantial effect, and if it is more than the above range, it may seep onto the surface (blooming phenomenon), which is not preferable. Fatty acid salts of group metals of the periodic table are
It is usually contained in an amount of 0.01 to 5% by weight, preferably 0.1 to 1.5% by weight, based on the polyolefin.

If the amount of the fatty acid salt of Group Group metal of the periodic table is less than the above range, there will be no substantial effect, and if it is more than the above range, it may reduce the transparency of the polyolefin, which is not preferable. The composition of the present invention may be produced by a method of adding conventional additives to polyolefin.

Specifically, examples include a method of mechanically blending each component, and a method of molding each component into chips after blending. Of course, the composition of the present invention may contain flame retardants, mold release agents, weather resistance improvers, stabilizers, heat resistant agents, antistatic agents, and dyes at any stage from before polymerization of polyolefin to molding of the final product.・It may be used in combination with additives such as colorants such as pigments, plasticizers, reinforcing agents, surfactants, inorganic fillers, lubricants, nucleating agents, or crosslinking agents, or polytetrafluoroethylene, polyester, ABS resin. Polymers such as can also be added.

Molding of the composition of the present invention can be carried out by various well-known methods. For example, by employing extrusion molding, molded products such as refilms and sheets can be made. In particular, suitable results are obtained when producing blown films. Of course, a T-dye film can also be produced using the composition of the present invention, and a film with good antifogging properties can be obtained.

The composition of the present invention has the following features due to the mutual effects of the above-mentioned components.

The effect of the composition of the present invention is that water droplets do not adhere to it.

Therefore, in the case of agricultural sheets or films, they do not harm the underlying crops. Also, if it is used as a packaging film, it will not be opaque. It also allows you to see the parts of your work closely, and it does not cause quality defects or spoilage. The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited in any way by the following Examples unless it goes beyond the gist of the invention.
7 and Comparative Examples 1 to 4 Low-density polyethylene NOVATECO-L''Fl3l manufactured by Mitsubishi Chemical Corporation, Sorbitan Monostearer-P Sorgen 50'' manufactured by Kogyo Seiyaku Co., Ltd. and zinc stearate in the amounts shown in Table 1. The mixture was blended and mixed at 140°C using a Banbury mixer to form pellets.

Using this pellet, a 100 μm film was inflation-molded at 180° C. using a 40 m 11 Lφ extruder. Using this film as a sample, the following antifogging test was conducted. 400m1 in 11 glass beakers
of water, covered with a sample film, and held diagonally so that the film surface was 20 degrees square with the horizontal surface for a sky exposure test.

After continuous exposure to the sky, large water droplets adhered to the lower part of the film, but the water droplets were almost completely spread out at the upper part, and the number of days until a slight trace of water droplets could be observed was expressed as the number of days. Examples 8 to 10 and Comparative Examples 5 and 6 In Example 1, the low density polyethylene was ethylene monovinyl acetate copolymer manufactured by Toyo Soda Kogyo Co., Ltd. (vinyl acetate was 15% by weight of the total) Ultracene UE63O, and a Banbury mixer was used. A film was formed under exactly the same conditions except that the mixing temperature was 125° C., and the same sky exposure test was conducted.

Claims (1)

[Claims] 1. A polyolefin composition for an antifogging film, comprising a fatty acid ester of sorbitan and a fatty acid salt of a Group II metal of the periodic table.