JPS6143536A - Polyethylene label - Google Patents

Abstract

PURPOSE:To obtain a polyethylene label which possesses no toxicity based on a plasticizer, does not have generation of harmful gas even at the time of combustion and is superior in transparency, by making use of straight-chain low-density polyethylene resin (LDPE) having short-chain ramification. CONSTITUTION:As for a LLDPE film, as it is apt to generate an ununiform thickness at the time of molding of raw fabric, it becomes difficult to stretch when an orientation temperature is lower than 70 deg.C, and when the temperature exceeds 110 deg.C, stable operation is hard to obtain as the film is apt to adhere to a roll, an article stretched monoaxially under terms of melt index of less than 8g/10min and a temperature range of 70-110 deg.C is being used as a polyethylene label. When density is less than 0.940g/cm<3>, if a draw ratio exceeds three times, transparency is improved suddenly, and it is capable of improving printability further by a general surface treatment such as corona discharge treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a heat-shrinkable polyethylene label used for packaging containers such as bottles and cans.

[Conventional technology]

Heat-shrinkable labels commonly used for the purpose of decorative effects and damage prevention for packaging containers are mostly uniaxially stretched polyvinyl chloride films or expanded polystyrene paper.

[Problem that the invention seeks to solve]

Stretched polyvinyl chloride film is manufactured by stretching polyvinyl chloride mixed with a plasticizer such as dioctyl phthalate in the transverse direction, so there are problems with the toxicity of the plasticizer and the large amount of chlorine gas generated during incineration. being watched.

In addition, in the case of foamed polystyrene paper, since it is opaque, it is not possible to print on the front side, and because of the front printing, the printing is likely to peel off due to friction during contact, resulting in a reduction in commercial value.

[Means for solving problems]

Therefore, the present inventors conducted various studies to solve the above-mentioned conventional problems, and as a result, the present inventors developed a linear low-density polyethylene resin (hereinafter referred to as LLDP) having short chain branches having 10 or less carbon atoms.
It was discovered that the above-mentioned problems of conventional labels could be solved by using a label (referred to as E).

Therefore, the purpose of the present invention is to provide a container that does not have the toxicity caused by plasticizers, does not generate harmful gases when burned, has excellent transparency, and has a sufficient decorative effect on containers, and that does not cause damage. It is an object of the present invention to provide a polyethylene label that can be used to prevent such problems.

According to research by the present inventors, the density of LLDPE is 0.9
It has been found that when the stretching ratio is 40 and 76 m3 or less, the stretching ratio is 3.0 (when it exceeds 3, the transparency increases rapidly).

However, not all LLDPE films are suitable as materials for heat-shrinkable labels; LLDPE films with a melt index exceeding 8'J/10m1n tend to have uneven thickness when forming the original fabric, and the stretching temperature is 70°C. If the temperature is less than 0.degree. C., it becomes difficult to stretch, and the film may break on the way, making it difficult to increase the stretching ratio to 2.0 times or more. On the other hand, if the temperature exceeds 1'10℃, the film tends to stick to the roll and it is difficult to achieve stable operation, so the melt index of 8r is recommended for polyethylene labels.
They have also found that it is limited to those that are uniaxially stretched at a temperature of 70 to 110° C. at a J/10 m1n or less.

The above LLDPE film was stretched with a roll diameter of 200 m/
Two stretching rolls of less than m and 10TrL/ between the rolls
This can be easily done with an air gap of TrL or less. The stretching direction of the film may be either vertical or horizontal, and when stretched within the range of 2.0 to 6.0 times, the film will undergo heat shrinkage only in the -axial direction. Furthermore, even with the same low-density polyethylene, low-density polyethylene with long chain branches obtained by high-pressure method has low shrinkage, lacks transparency, and has a density of 0.94! High-density polyethylene with a density exceeding 1/cm" has poor transparency, and polypropylene has a high shrinkage temperature.

[For production]

Labels made of the uniaxially stretched LLDPE film are less likely to undergo biaxial heat shrinkage and have high transparency like vinylon films. Furthermore, it has become possible to improve printability by using general surface treatments such as corona discharge treatment.

[Example, comparative example]

By extrusion UN (55m/mφ), the melt index is 0. ! +-7,0'j/1011in, density 0.9
Table 1 shows Examples 1 to 5 of labels obtained by air-cooling and blowing an LLDPE film (40 μm) with a weight of 35 g/cm 3 or less and uniaxially stretching the film.

In addition, as Comparative Examples 1 to 3, labels were prepared using a low-density polyethylene resin (hereinafter referred to as LDPE) film having long chain branches produced by a high-pressure method as the material, and subjected to IIJ HW under the same conditions as in the examples. As Comparative Example 4.5, the LLD, PE film was stretched at a different stretching temperature from the present invention, and the results are shown in Table 2.

In addition, the shrink suitability in the table is for film (130s
This is the result of heat-sealing both ends of the pin (2° Omm) in the direction of shrinkage to form a sleeve, and then wrapping the sleeve over the body of the pin and shrinking it. Of the 43 cases, haze was ASTM
According to D1003.

Table 1 Table 2 (Effects of the invention) As mentioned above, the present invention has the following advantages, as is clear from the comparative examples:
It has many advantages such as excellent transparency and heat shrinkability, and unlike conventional vinyl chloride labels, it does not have the toxicity caused by plasticizers, and it does not emit harmful gases when burned.

Claims (1)

[Claims] A polyethylene label comprising a linear low-density polyethylene resin film having short chain branches with a melt index of 8 g/10 min or less, and uniaxially stretched at a temperature range of 70 to 110°C.