JPS6167883A - Polyethylene label - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

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

[Prior Art] Most heat-shrinkable labels commonly used for the purpose of decorating packaging containers and preventing damage are made of stretched polyvinyl chloride films or expanded polystyrene paper.

[Problem to be Solved by the Invention 1] Stretched polyvinyl chloride films are produced by stretching polyvinyl chloride to which a plasticizer such as dioctyl tstalate has been added. The chlorine gas generated is considered a problem.

Furthermore, in the case of foamed polystyrene vapor, 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 the Problems] Therefore, the present inventors conducted various studies to solve the above-mentioned conventional problems. Polyethylene resin (hereinafter referred to as LLDP)
They discovered that by using a label (called E), the above-mentioned problems of conventional labels could be solved and a label V could be created.

Therefore, the object 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, has a sufficient decorative effect on containers, and furthermore prevents breakage. Another object of the present invention is to provide a polyethylene label that can be used in various applications.

According to the research conducted by the present inventors, all LLDPE noilms are suitable as materials for heat-shrinkable labels, but only those with a melt index of 8 g/IQmin or less and a water-cooled film temperature of 70 to 110°C. It has become clear that those uniaxially stretched in a temperature range of .

The LLDPE of the present invention has a melt index of 8 g/101
If it exceeds in (JIS K6760), uneven thickness is likely to occur when forming the original fabric. Also, is the original fabric water-cooled? High transparency can be imparted to the label by using a John film or a water-cooled T-die film. If the original film is an air-cooled inflation film, the transparency is not as good as that of the label of the present invention. Further, if the stretching temperature is lower than 70° C., the film resistance increases and it becomes difficult to stretch, and the film may break on the way, making it difficult to increase the stretching ratio to 2.0 g1 or more. On the other hand, if the temperature exceeds 110°C, the film tends to adhere to the rolls, making it difficult to obtain stable operation. Note that the stretching ratio is preferably 318 or more from the viewpoint of transparency.

The above LLDPE Noilm was stretched with a roll diameter of 200 m/
Two stretching rolls of less than m and 10 nL/m between the rolls
This can be easily done with the following air gap. 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.

Even with the same low-density polyethylene, low-density polyethylene with long chain branches obtained by a high-pressure method has poor shrinkage and lacks transparency, while high-density polyethylene with a density exceeding 0.945 LJ/cm3 has low transparency. This is poor, and polypropylene has a high shrinkage temperature.

[Function 1] The label made of the uniaxially stretched film of LLDPE is unlikely to undergo heat shrinkage in the direction of the two wheels and has high transparency.

Furthermore, printability can be improved by surface treatment such as corona discharge treatment.

Examples 1 to 6, Comparative Examples 1 to 5 Melt index 89/10 iin or less, density 0
．． Original LLDPE film of 9359/13 or less (20
0μ thickness) by water-cooled inflation molding (Examples 1 to 5)
Table 1 shows the labels obtained by uniaxially stretching the original film by subjecting the original film to downstream water-cooled T-die molding (Example 6).

Examples 1 to 5 except that low density polyethylene (hereinafter referred to as LDPE) having long chain branching by high pressure method was used.
(Comparative Example 1.2), except that the original film was air-cooled inflation molded, and the same as Examples 1 to 6 (Comparative Example 3), except that it was stretched at a temperature different from that of the present invention. Table 2 shows the cases in which the same procedure as in Examples 1 to 6 (Comparative Example 6) was carried out, except that L was used in the same manner as in Examples 1 to 5 (Comparative Example 4.5), and the original film was formed by chill roll T-die molding.

In addition, the haze in Table 1.2 is determined by ASTM DIO03, the heat shrinkage rate TD (-) means expansion, and the shrink suitability is 130 s x 220 an. It has the appearance of being shrunken over the top.

Moreover, the original fabric forming conditions are as follows.

Extruder Inflation method 55#l#Iφ L/D=28 T die method 65111IIIφ L/D=28 Die Inflation method 150m+φ Lip gap LLDPE 2.5zmL D
P E 1 mm T-die method 600 medium lip gap 1 mm 'Temperature L
'LDPE 170~200℃LDPE 180
℃ Water cooling Temperature 20℃ However, fabric is provided on the inner wall (film side) of the water cooling ring (for folding diameter 420a+m).

What is the down-flow water-cooling T-Gui method? Cooling air is applied to the molten resin from the die from an air knife, and then the resin is cooled through a flow-down water cooling system, where cold fJI water flows down with a thin film in between. means.

Chill roll temperature: 20°C (blank below) Table 1 Table 2 [Effects of the invention] As mentioned above, the polyethylene label of the present invention has excellent transparency and heat shrinkability, and unlike conventional vinyl chloride labels, it does not contain plasticizers. It has many advantages, such as being non-toxic and producing no harmful gases when burned.

Claims (1)

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