JPS5914060B2 - adhesive polyethylene film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an adhesive polyethylene film, and more particularly, the present invention relates to a pressure-sensitive adhesive polyethylene film, and more specifically, it is made of a composition in which a specific low-density polyethylene, a specific high-density polyethylene, and an antifogging agent are blended. The present invention relates to an adhesive polyethylene film having excellent properties such as hardness, anti-fogging properties, transparency and cutting properties.

Adhesive films are used as wrap films or stretch films in supermarkets, department stores, grocery stores, or at home to store fresh foods such as vegetables, fruits, meat, and fish.
Alternatively, it is widely used as a simple packaging film for these processed products and various containers containing them.

However, since conventional adhesive films mainly use vinyl chloride resins such as polyvinyl chloride and polyvinylidene chloride, they all contain 1 molecule in their molecules.
It contains zero chlorine, and therefore releases harmful gases when incinerated after use, causing pollution. In addition, these adhesive films contain a large amount of weighting agents and stabilizers, so during use, these weighting agents and stabilizers may transfer to foods that come into contact with them and cause harmful effects. , giving off an unpleasant odor. On the other hand, polyion fin-based films, especially low-density polyethylene films, have the advantage of not emitting harmful gases when burned, but on the other hand, they can be used to reduce the amount of heat produced by molding at normal molding temperatures, such as 190 to 250°C.
Films have poor self-adhesion and low melting points, so if you package fish meat containing oil or fat and heat it in a microwave, for example, the film will easily melt or break due to the heat of the oil and fat, resulting in poor heat resistance. It has drawbacks such as poor cutting performance, that is, poor sharpness when the film is pulled out from the film roll 25 and cut with a tooth-shaped cutter.
From this point of view, the present inventors conducted various studies for the purpose of improving the above-mentioned drawbacks that low-density polyethylene films have, and as a result, ? 0 We have discovered that an adhesive film made of a composition containing a specific high-density polyethylene and an antifogging agent has excellent processability, heat resistance, antifogging properties, transparency, and cuttability, leading to the present invention. .

The low density polyethylene used in the present invention has a density of 0.924 to 0.930 g/h, a melt index (temperature of 190°C, load of 2.16 to 9, hereinafter abbreviated as MI) of 1 to 81/10 min. It is something.

When the degree of density is 0.9249/d or less, the melting point is too low, and there is a drawback that the film may melt or be damaged when oil-containing foods such as fish are packaged and heated in a microwave oven.

On the other hand, if the density exceeds 0.930 g/CTil, tackiness and transparency will decrease, which is not preferred in practice. Also,
If MI is less than 19/10 minutes, high-speed machining is difficult.
When the MI exceeds 10 f1/10 minutes, drawdown properties are poor and high-speed processing is difficult, similar to low density polyethylene with an MI of 19/10 minutes or less. The high-density polyethylene blended with the low-density polyethylene has a density of 0.9459/d or more and an MI of 2 to 10 f! /10 minutes, and CIL. The ratio of flow index to M is 2 or less.

Here CIL. Flow index (hereinafter abbreviated as CIL) is a method by the Canadian Industrial Laboratory at a temperature of 190°C and a nitrogen gas pressure of 100°C.
It is an index that measures the outflow amount of the polymer in a molten state in kg/d and expresses this in units of 9/10 minutes.

If the density of the high-density polyethylene is 0.9459/d or less, the sharpness during cutting will not be improved and the effects of the present invention will not be obtained.

Further, if the MI is 29/10 minutes or less or 109/10 minutes or more, high-speed processing is difficult as in the case of low-density polyethylene. If the ratio of CIL to MI is 2 or more, it is not preferable because transparency, processability, and adhesiveness deteriorate.
In order to improve the transparency of the adhesive film of the present invention, it is necessary to contain at most 0.015% by weight of internal vinylidene groups and at most 0.015% by weight of terminal vinyl groups in the molecules of the high-density polyethylene to be blended. Preferably, it is present in an amount of 0.02% by weight. The amount of high density polyethylene blended is 20 to 30 parts by weight per 100 parts by weight of low density polyethylene. If the amount is less than 20 parts by weight, the effects of improving heat resistance and cutting properties will be insufficient, while if the amount exceeds 30 parts by weight, transparency and adhesiveness will decrease, which is not preferable. The antifogging agent used in the present invention is blended to prevent water droplets from adhering to the inner surface of the film when packaging foods containing moisture such as vegetables. Any of them may be used, and particularly glycerin fatty acid ester, polyoxyethylene alkyl phenyl ether, sorbitan fatty acid ester, etc. are most suitable.

These antifogging agents may be used alone or in combination of two or more. The amount of the antifogging agent to be added varies depending on the type of low-density polyethylene used, but is 0.5 to 2 parts by weight per 100 parts by weight of low-density polyethylene.

If the amount of the antifogging agent is less than 0.5 parts by weight, the tackifying effect will not be sufficiently exhibited, while if it is more than 2 parts by weight, the film will become sticky or easily stained, which is not preferred. In the present invention, the method of mixing high-density polyethylene and antifogging agent with low-density polyethylene includes a roll mill, a Banbury mixer, a kneader, a drum tumbler, an extruder, etc., which are commonly used in the synthetic resin industry. It can be done with

Methods for adding high-density polyethylene and anti-fogging agent include adding high-density polyethylene and anti-fogging agent to low-density polyethylene at the same time, or adding them separately at any time before molding the low-density polyethylene. Any method may be used, and there is no particular restriction on the order of addition. In the present invention, ultraviolet absorbers, anti-blocking agents, lubricants, and other additives can be added as necessary, as in the usual case. The T-die method, the inflation method, etc. are known as methods for producing the adhesive polyethylene film of the present invention, but the T-die method is used to improve the adhesiveness and transparency of the resulting film. , die temperature 3
It is preferable to conduct the reaction at a temperature of 00 to 360°C.

Since the adhesive polyethylene film obtained by the present invention does not contain chlorine or the like in its molecules, it does not emit harmful gases when burned, and it does not emit harmful gases when burned, and it does not contain any harmful gases such as those conventionally used for vinyl chloride resins. Since it does not contain harmful additives, the additives will not be transferred to foods or produce any unpleasant odors.

Furthermore, the adhesive polyethylene film of the present invention has excellent processability, antifogging properties, cutting properties, and transparency, and in particular does not melt or break even when used in a microwave oven, and has excellent heat resistance. It offers new uses as a packaging film. Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

In addition, each physical property test in Examples and Comparative Examples was conducted according to the following.

Microwave characteristics (heat resistance) Pork placed on a plate was wrapped in a film and heated in a 600W microwave oven for 5 minutes, and the film was visually observed for melting and damage. , ×).

◎ Does not melt ○ Part of the talum does not melt △ Part melts × The whole part melts Cutting property When the film is pulled out from the film roll and cut with a tooth-shaped cutter, the 4-point method (◎, It was judged as ○, △, X).

◎ Very good ○ Good △ Poor × Very poor Transparency The degree of haze (010) was measured in accordance with ASTM D-1003 method.

90m77 equipped with a processable T-die! A film having a thickness of 0.015 m1w was formed using a φ extruder at a winding speed of 80 m/min, and the stability of the film formation at that time was observed with the naked eye.

◎ Extremely good O Good △ The stability of the ears is poor and there is a tendency to surge.

× Membrane breakage or surging.

Sticky vegetables, meat, etc. were wrapped in a film, the ends of the film were bent and pressed together with fingers to make the films stick to each other, and the stickiness of the films to each other was evaluated using the following four-point method.

◎ Very good O Good △ Shows tackiness but poor persistence The first agent (polyglycerol oleate)
They were blended in the proportions shown in the table, and then pelletized using a 65 mm diameter extruder at an extrusion temperature of 170°C.

The obtained pellets were heated using a 90 mmφ extruder equipped with a T-die at a die temperature of 350°C, a cooling roll temperature of 35°C,
A film having a thickness of 0.015 mm was formed at a winding speed of 80 m/min. Table 1 shows the physical properties of this film. Comparative Example 5 A film was molded in the same manner as in Example 1 except that no antifogging agent was added.

The physical properties of this film were as follows. Microwave characteristics ○ Cutting characteristics ◎ Haze (%) 1.3 Processability ◎ Adhesion ×

Claims (1)

[Claims] 1 (A) Density 0.924-0.930g/cm^3,
To 100 parts by weight of low density polyethylene with a melt index of 1 to 8 g/10 minutes, (B) density 0.945 g/cm^
3 or more, melt index 2-10g/10min, CI
High-density polyethylene having a ratio of L-flow index to melt index of 2 or less and having at most 0.015% by weight of internal vinylidene groups and at most 0.02% by weight of terminal vinyl groups in the molecule An adhesive polyethylene film comprising a composition containing 30 parts by weight and 0.5 to 2 parts by weight of (C) an antifog agent.