JPS6295341A - Polyester shrink label having improved low-temperature heat shrinkability - Google Patents

Abstract

PURPOSE:A polyester shrink label having improved low-temperature heat shrinkability, comprising a copolyester containing 1,4-cyclohexanedimethanol in a diol component and polyethylene terephthalate. CONSTITUTION:A composition obtained by blending (A) 50-99wt% copolyester comprising (i) an aromatic dicarboxylic acid component, preferably terephthalic acid (derivative) and (ii) a diol component, preferably ethylene glycol containing 10-40mol%, preferably 15-35mol% 1,4-cyclohexanedimethanol with (B) 1-50wt% polyethylene terephthalate is extruded by the use of a T die, stretched, cut and sealed at the center to give a cylindrical shrink label.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention particularly relates to a polyester shrink label comprising a specific component composition that has excellent low-temperature heat shrinkability.

As for cylindrical shrink labels, those using heat-shrinkable films made of polyvinyl chloride have traditionally been widely used, but these tend to lack strength, so they cannot be used for large containers such as single-sentence containers. Protective labels to prevent scattering in the event of a rupture, etc., are insufficient because the gas pressure inside the container is too high, and the transparency is somewhat insufficient, and they are weak and slippery. It has also been pointed out that this product is difficult to handle during mechanical packaging, and that its mechanical packaging properties are somewhat inferior. Furthermore, when the waste, dust, etc. are incinerated, they generate hydrochloric acid gas, which can corrode the furnace, and various waste disposal organizations have requested improvements.

On the other hand, ordinary polyester films obtained by polycondensing terephthalic acid and ethylene glycol have chemical resistance,
It has excellent physical properties such as solvent resistance, mechanical properties, and transparency, and also has few calories when burned and does not produce harmful substances, making it easy to dispose of waste. It lacks heat shrinkability, and furthermore, its heat shrinkability is not sufficient, so it is currently not generally used as a shrink label.

The present inventors searched for various polyesters that not only have the properties of polyester films but also have various properties such as low-temperature heat shrinkability that should be comparable to shrink labels made of polyvinyl chloride. A useful polyester heat-shrinkable film has been discovered, and the gist of the present invention is that it is composed of an aromatic dicarboxylic acid component and a diol component, and the diol component is 1,4-cyclohexaline methanol. 10-4
50-99% by weight of copolyester present in 0 mol%;
Polyethylene terephthalate 1 to 50% by weight.

The present invention will be described in detail below along with examples.

Examples of the aromatic dicarboxylic acid component of the copolyester according to the present invention include terephthalic acid or its derivatives, such as dimethyl terephthalate and diethyl terephthalate, and examples of the diol component include ethylene glycol and propylene glycol. However, the present invention is not limited to the above examples. The diol component contains 10
-40 mol% of 1,4-cyclohexalinemethanol is required, and in this case 15-35 mol%
′ is more preferably present. If the 1,4-cyclohexalinemethanol content is more than 40 mol%, the viscosity becomes high and extrusion molding becomes difficult, and if it is less than 10 mol%, the impact resistance and heat sealability are reduced. The most preferred copolyester according to the present invention is one consisting of terephthalic acid or a derivative thereof and ethylene glycol containing 10 to 40 mol% of 1,4-cyclohexalinemethanol.

Next, as polyethylene terephthalate according to the present invention, for example, a polymer obtained from terephthalic acid or its derivatives (for example, dimethyl terephthalate, diethyl terephthalate, etc.) and a diol such as ethylene glycol can be exemplified, and is generally called polyethylene terephthalate. It is something that will be done. At this time, this polyethylene terephthalate is 1 to 99% by weight of the copolyester.
50% by weight is used. However, in the present invention, in addition to the above-mentioned composition, various antistatic agents, lubricants, and other appropriate fillers may be added as necessary. In the present invention, if the amount of copolyester is less than 50% by weight, it is difficult to obtain easy heat-sealability and high shrinkage properties, and if it exceeds 99% by weight, the strength will decrease significantly and the feel and stiffness will be inferior. Often.

Labels with the above-mentioned specific component composition of the present invention are usually made from a film obtained by polyblending the required amount of raw resin and then undergoing a stretching process after extrusion film formation.Generally, however, it is produced by a flat extrusion method such as the T-die method. The film is produced by stretching in the l-axis, which is preferable for label manufacturing, as well as in the z-axis and multi-axes, cutting, and then applying a center seal.

Of course, instead of the flat extrusion method described above, extrusion film formation by a tubular method is also possible. At this time, if a stretching step is not performed, a label with preferable low-temperature shrinkability cannot be obtained, but this stretching may be performed under appropriate conditions after the sheet is once formed by extrusion film formation, for example. One example is a method in which after extrusion film formation, the film is subsequently stretched horizontally or vertically in the l-axis using a tenter, rolls, etc., and it is of course preferable to carry out the stretching in a so-called low temperature range, such as 60 to 120°C. The above temperature range is merely an example, and the present invention is not limited to this range. Further, a sequential biaxial stretching method, a simultaneous biaxial stretching method, etc. can be adopted as necessary. In this case, it is preferable to stretch the cylindrical label so that the heat shrinkage rate in the longitudinal axis direction is close to O, but
Of course, the heat shrinkage rate may be appropriately determined as necessary. Labels are made from film by center-sealing a flat film to make it into a cylinder, but tubular films can also be used as they are without canting.If a uniaxially stretched film is used, the stretching direction is the same as the label. Although it is preferable to use it so that it coincides with the circumferential direction of , it is of course not limited to this.

The shrink label according to the present invention is particularly suitable for glass bottles, plastic containers, such as polyethylene terephthalate containers, metal cans, etc., but there is no particular restriction on the use, and it can be applied to any field as necessary. be.

The present invention is as described above, and since the shrink label of the present invention has excellent low-temperature shrinkability, it is possible to shrink at low temperatures, and it does not corrode the furnace etc. when incinerating waste etc.
It is extremely useful and has excellent physical properties, and is expected to be in high demand in the future.

Next, the present invention will be explained in more detail with reference to Examples.

<Example> Copolyester obtained from dimethyl terephthalate and ethylene glycol containing 30 mol% of 1,4-cyclohexalinemethanol: Polyblend of polyethylene terephthalate obtained from dimethyl terephthalate and ethylene glycol The composition was extruded to a thickness of 200 mm using a T die, and then extruded to a thickness of 75 mm using a tenter.
A polyester shrink film having a thickness of 10 AL and having low-temperature heat shrinkability was obtained by performing 5-fold transverse stretching at .degree. This film was printed and cut into the necessary dimensions to make a cylindrical shrink label with a diameter of about 90 cm. Then, a cylindrical shrink label was created by applying a center seal using an appropriate solvent or heat sealing. At this time, the circumferential direction of the label was made to match the stretching direction.

In producing the shrink film, experiments were conducted with various blending ratios of copolyester and polyethylene terephthalate as shown in Experiments No. 1 to No. 3, and the data are shown in Table 1.

As can be seen from this table, the shrink film used to make the labels according to the present invention not only has extremely excellent low-temperature shrinkability, but also has excellent physical properties such as transparency, stiffness, and gloss. I understand.

Furthermore, when such a label was placed on a one-sentence glass bottle container with a body diameter of 88rstx and heat-shrinked using a shrink tunnel to cover the container, there was little dimensional change in the axial direction during shrinkage, resulting in a beautiful covering. A container was obtained. In addition, the label for refusing had good solvent resistance and had beautiful multicolor printing.

Next, the weather resistance of the label according to Example (2).

Table 2 shows the results of the bursting test and combustion test.

At this time, the burst test used a crow bottle with the label covered with heat shrinkage.

As is clear from these data, the product of the present invention has exceptional effects as described in the specification, but the comparative example (
Comparative example (2) is unfavorable because the shrinkage rate is difficult to produce and the unnecessary vertical shrinkage rate is too large.Comparative example (2) has an increase in yield 11:Jl due to temperature rise compared to the example. It was not smooth and rose sharply around 75°C, making it difficult to obtain a beautiful coating effect.

In Tables 1 and 2, the longitudinal direction and the latitudinal direction refer to the direction in which the film is molded, and the latter to the direction perpendicular to the molding direction, that is, the stretching direction.

Claims (1)

[Claims] A copolyester 50-99 consisting of an aromatic dicarboxylic acid component and a diol component, in which the diol component contains 10-40 mol% of 1,4-cyclohexalinemethanol.
Weight%: polyethylene terephthalate 1-50% by weight
A polyester shrink label with excellent low-temperature heat shrinkability, characterized by the following: