KR101530699B1 - Heat-shrinkable polyester film - Google Patents

Abstract

The present invention relates to a transparent polyolefin film obtained from a polyester resin having a copolymer comprising a terephthalate component and a diol component, wherein the film has a pore size of from 80 to 300 nm in the range of 25% to 50% The present invention relates to an ester-based heat-shrinkable film. The film according to the present invention has excellent heat shrinkability, transparency deterioration due to scattering of light is not caused, and exhibits a volume specific gravity lower than that of water. And it is also effective in terms of recycling.

Description

 Heat-shrinkable polyester film {HEAT-SHRINKABLE POLYESTER FILM}

The present invention relates to a film comprising a polyester resin having a copolymer comprising a terephthalate component and a diol component, wherein the film comprises 25% to 50% of a perforation having a diameter of 80 nm to 300 nm, And a polyester-based heat-shrinkable film.

As a heat-shrinkable film, polyvinyl chloride (PVC) film and stretched polystyrene (OPS) film have been used for a long time. PVC heat shrinkable film has excellent molding processability and low shrinkage stress, and exhibits excellent properties for labeling and shrink wrapping in various types and types of containers. However, in recent years, due to environmental pollution problem, limit shrinkage rate not exceeding 65% , The use of polyester-based heat-shrinkable films that are environmentally friendly, heat-resistant and have a high heat shrinkage ratio is increasing. In addition, the OPS heat-shrinkable film is insufficient in heat resistance and is not suitable for shrink labels such as glass or metal cans, and has a limitation in that it is difficult to apply to a high-temperature filling such as a fruit juice drink.

The demand for polyester heat-shrinkable films having heat resistance and high heat shrinkage ratio compared to PVC films and OPS films is increasing, but it is not easy to separate them after shrinking the container and film, .

A common method for facilitating the separation of a container from a label in a heat-shrinkable film is to separate it from water using a difference in specific gravity between the container and the label. Currently, the container and the film have a volume specific gravity greater than water, , Especially in the case of PET containers, the separation is more difficult because they have the same specific gravity. Accordingly, in order to separate the film using the specific gravity difference, development of a heat-shrinkable label is in progress by replacing the film material itself with an olefin resin (such as polypropylene or polyethylene) having a low specific gravity. However, Not only the heat shrinkability is not expressed but also the shrinking behavior is also different, which can cause a considerable problem to be applied.

In addition, there is a method for producing a heat-shrinkable film by forming pores in a polyester film without changing the material of the film. However, it is impossible to maintain transparency inherent in the polyester film due to scattering of light due to pores existing in the film. Thus, there is a disadvantage that it can be applied marginally only for white printing use.

In general, the size of a water molecule is about 1 nm. However, due to its surface tension, the actual size of the water droplet is several hundreds to several tens of times larger than the size of the water. In reality, Even if it is maintained, it exhibits sufficient performance to prevent penetration of water by forming a fine film which can not penetrate water between fibers.

Accordingly, while studying to solve the above-mentioned quality problems, the film material is not changed, but the water is not penetrated by using the laser drilling processor technique currently applied in the field of food packaging film, but air can be kept in a collected state It is possible to produce a polyester heat-shrinkable film that can float in water while maintaining the same appearance and shrinkage properties as existing polyester-based heat-shrinkable films by forming fine pores having a specific size and area ratio Thus completing the present invention.

Accordingly, an object of the present invention is to provide a heat-shrinkable polyester film which can float in water while maintaining the same appearance and shrinkage properties as a conventional polyester-based heat-shrinkable film, and has excellent heat shrinkage and transparency.

Another object of the present invention is to provide a packaging material or label comprising the above polyester-based heat-shrinkable film.

In order to achieve the above object, the present invention provides a film obtained from a polyester resin having a copolymer comprising a terephthalate component and a diol component, wherein the film has a pore diameter ranging from 80 to 300 nm, % Based on the total weight of the heat-shrinkable film.

In order to achieve the other object, the present invention provides a packaging material or a label comprising the polyester-based heat-shrinkable film.

The polyester-based heat-shrinkable film of the present invention can be produced by using a material used for a conventional polyester-based heat-shrinkable film and by including perforations in the film, thereby exhibiting excellent heat shrinkability, Not only does not occur, but also exhibits a volume specific gravity lower than that of water, so that the container and the film can be easily separated later, which is effective in terms of recycling.

1 is a schematic view of a transparent polyester-based heat-shrinkable film of the present invention.

The present invention relates to a film comprising a polyester resin having a copolymer comprising a terephthalate component and a diol component, wherein the film comprises 25% to 50% of a perforation having a diameter of 80 nm to 300 nm, A polyester-based heat-shrinkable film is provided.

In the present invention, the perforation is a size that is not visually recognizable and does not scatter at the wavelength of the visible light region without changing the physical properties of the film (such as haze and light transmittance), for example, 80 to 300 nm, To 200 nm in diameter. If the diameter of the perforations is more than 300 nm, the appearance characteristics of the film are deteriorated, and the film is easy to be visually perceived as a foreign substance, so that the aesthetic function as a packaging film can be lost. On the other hand, when the diameter of the perforations is less than 80 nm, scattering of light occurs and transparency may be lowered.

The perforation is characterized in that the perforation area ratio is 25% to 50%, preferably 30% to 40%, based on the entire film area, in order to exhibit a volume specific gravity that can be suspended in water. If the area ratio of the perforations is less than 25%, the film may not show sufficient volume specific gravity to float on the water, so that the label and the bottle may not be separated from each other due to floating in water. It is not preferable due to the lowering of the physical properties and the rapid decrease of the production rate in the post-process and the rapid increase of the defect rate.

In the present invention, the terephthalate component is ethylene terephthalate and the diol component is 2,2-dimethyl-1,3-propanediol. Accordingly, the film according to the present invention can be obtained from a polyester resin containing ethylene terephthalate as a main repeating unit and 2,2-dimethyl-1,3-propanediol in the copolymer component.

The 2,2-dimethyl-1,3-propanediol is preferably contained in an amount of 1 to 50%, preferably 10 to 30% by weight, based on the total weight of the copolymer.

The copolymer may further contain, in addition to 2,2-dimethyl-1,3-propanediol, a component capable of reducing the crystallinity of the film. These components may be selected from the group consisting of 1,2-octanediol, 1,3-octanediol, 1,3-butanediol, 2-butyl-2-ethyl-1,3-propanediol, 2,2- Diol, 2,4-dimethyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,1-dimethyl-1,5-pentanediol, diethylenediol, 1,4-cyclohexanediol , 1,4-cyclohexanedimethanol (CHDM), and mixtures thereof, and 1,4-cyclohexanedimethanol may be preferably used. Such additional copolymer components may be included in an amount of 0 to 40% by weight based on the total weight of the resin.

In the case of 1,4-cyclohexanediol among the above-mentioned components, 1,4-cyclohexanediol such as polyethylene terephthalate glycol (PETG), polycyclohexylenedimethylene terephthalate glycol (PCTG), etc. copolymerized in an appropriate amount or separately commercialized, Diol containing resins can be used by blending.

The present invention can comprise a copolymer comprising 2,2-dimethyl-1,3-propanediol in an amount of from 1 to 50% by weight, preferably from 10 to 30% by weight, based on the total weight of the polyester- have.

The polyester-based heat-shrinkable film according to the present invention may contain various additives such as a polymerization catalyst, a dispersant, an electrostatic agent, an antiblocking agent, and other lubricants well known in the art within the range not impairing the effects of the present invention have.

According to one embodiment of the present invention, the polyester-based heat-shrinkable film of the present invention exhibits a range of 0.7 to 1 in which the bulk specific gravity of the film can float in water. Further, the film of the present invention has a roof stiffness of 2 or more, a haze of the film of 10% or less, and a heat shrinkage of 30% or more at 90 占 폚 hot water in at least one axial direction (see Test Example) .

The heat-shrinkable polyester film according to the present invention preferably has a thickness of 20 to 80 탆. When the film has a thickness in the above range, it has excellent stretch uniformity, and is excellent in heat shrinkage uniformity, ink adhesion, water and gas barrier properties, crack resistance, and rupture resistance when used for labeling or packaging.

Based on the above characteristics, the polyester-based heat-shrinkable film of the present invention is excellent in heat shrinkability by producing the polyester-based heat- Not only transparency deterioration due to the development does not occur but also a volume specific gravity lower than that of water is exhibited, so that the container and the film can be easily separated later, which is effective in terms of recycling.

The polyester-based heat-shrinkable film according to the present invention can be produced by preparing a polyester film by a conventional method known in the art and then punching a hole having a diameter of 80 to 300 nm by using a separate laser perforator capable of forming a perforation Based on the entire film area, to be 25% to 50%. For example, the perforating apparatus used in the perforating process may be a CO ₂ laser perforating apparatus of the LOPIN Corporation.

The present invention also provides a packaging material or label comprising the polyester-based heat-shrinkable film.

[ Example ]

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the following examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

Example 1: Preparation of heat-shrinkable polyester film

A copolymer comprising 17% by weight of 2,2-dimethyl-1,3-propanediol with ethylene terephthalate as a main repeating unit, and a copolymer comprising ethylene terephthalate as a main repeating unit and 17% by weight of 1,4- Hexane dimethanol, and then a polyester resin containing the copolymers in a ratio of 1: 1 was prepared. At this time, the polymerization reaction conditions and other process conditions are in accordance with the standard production method of polyester film which is commonly used in the technical field of the present invention and well-known. The polyester resin is melt-extruded through a T-die And stretched 4.0 times in the TD direction to obtain a polyester film having a thickness of 50 mu m.

The thus-obtained polyester film was subjected to a laser drilling process using a CO ₂ laser perforation apparatus manufactured by Loffin Co., Ltd., and heat-shrinkable polyester film having a perforation diameter of 100 nm and an area ratio of perforations of 30% .

Example 2: Preparation of heat-shrinkable polyester film

The procedure of Example 1 was repeated to prepare a film, except that the perforation size was 100 nm in Example 1, and the area ratio of perforations was adjusted to 40% based on the total film area.

Example 3: Preparation of heat-shrinkable polyester film

The procedure of Example 1 was repeated to prepare a film, except that the size of the perforation in Example 1 was 200 nm and the area ratio of the perforations on the film was adjusted to be 40% of the total area.

Comparative Example 1

The procedure of Example 1 was repeated to prepare a film, except that the size of the perforation was 100 nm in Example 1 and the area ratio of the perforations on the film was adjusted to 10% of the total area.

Comparative Example 2

Except that the perforation size in Example 1 was 400 nm and the area ratio of the perforations on the film accounted for 60% of the total area. The procedure of Example 1 was repeated to produce a film.

Test example: evaluation of film characteristics

1) Bulk density

The volume specific gravity of the films prepared in Examples 1 to 3 and Comparative Examples 1 and 2 was measured according to ASTM D792 using an XP204V device manufactured by Mettler Toledo Co. The results are shown in Table 1 below.

2) Hayes

The haze (%) of the films prepared in Examples 1 to 3 and Comparative Examples 1 and 2 was measured in accordance with ASTM D1003 using a NDH5000W instrument manufactured by Nippon Denshoku Kogyo Co. The results are shown in Table 1 below .

3) Loop stiffness

The films prepared in Examples 1 to 3 and Comparative Examples 1 and 2 were cut at a width of 15 mm (TD direction) and a length of 100 mm, and both ends were fixed to a measuring device (Toyoseki Loop Stiffness tester) I bent the film. The load sensor was touched at the center of the curved film to measure the stiffness (gf) at the center. The results are shown in Table 1 below.

4) Heat shrinkage

The films prepared in Examples 1 to 3 and Comparative Examples 1 and 2 were cut to a width of 15 mm (TD direction) and a length of 300 mm, heat treated in a constant temperature water bath maintained at 90 캜 for 10 seconds, Was used to calculate the heat shrinkage rate. The results are shown in Table 1 below.

[Equation 1]

Heat shrinkage percentage (%) = [(initial length - length remaining after heat treatment (mm)) / initial length] * 100

Area ratio of perforation (%) Size of perforation (nm) Bulk specific gravity Haze (%) Loop stiffness (gf) Heat shrinkage rate at 90 占 폚 (%) Example 1 30 100 0.93 5.6 4.2 42 Example 2 40 100 0.8 6.1 3.9 60 Example 3 40 200 0.78 6.2 3.7 52 Comparative Example 1 10 100 1.2 5.6 4.5 72 Comparative Example 2 60 400 0.5 7.6 1.1 61

As shown in Table 1, the film according to the present invention is produced by making perforations having a diameter of 100 to 200 nm to account for 25 to 50% of the total area ratio of the film, so that transparent heat shrinkage having a volume specific gravity in the range of 0.7 to 1 It was possible to obtain a cast polyester film. However, in Comparative Example 1, which is out of the above range, the recyclability of the heat-shrinkable film is low, and in Comparative Example 2, there is a high possibility of causing problems in a shooting process of covering labels after printing due to low loop rigidity.

Claims (11)

A perforation having a diameter of 80 nm to 300 nm, which is obtained from a polyester resin having a copolymer containing a terephthalate component and a diol component, in an amount of 30% to 40% based on the total film area, Wherein the heat-shrinkable film is formed by using a thermoplastic resin. The method according to claim 1,
Wherein the terephthalate component is ethylene terephthalate and the diol component is 2,2-dimethyl-1,3-propanediol. The method according to claim 1,
Wherein the perforations have a diameter of 100 nm to 200 nm. delete 3. The method of claim 2,
Wherein the 2,2-dimethyl-1,3-propanediol is contained in an amount of 1 to 50% by weight based on the total weight of the copolymer. The method according to claim 1,
Wherein the copolymer is selected from the group consisting of 1,2-octanediol, 1,3-octanediol, 1,3-butanediol, 2-butyl- 1,2-pentanediol, 1,1-dimethyl-1,5-pentanediol, diethylenediol, 1,4-cyclohexane Diol, 1,4-cyclohexanedimethanol, and mixtures thereof. ≪ RTI ID = 0.0 > 11. < / RTI > The method according to claim 1,
Wherein the film has a volume specific gravity of 0.7 to 1. 2. The transparent heat- The method according to claim 1,
Wherein the film has a roof stiffness of not less than 2, and a transparent polyester-based heat-shrinkable film. The method according to claim 1,
Wherein the haze of the film is 10% or less. The method according to claim 1,
Wherein the film has a heat shrinkage of at least 30% after heat-treating the film in a direction of at least one axis at 90 캜 in hot water for 10 seconds. A packaging material or label comprising the polyester-based heat-shrinkable film according to any one of claims 1 to 3 and 5 to 10.

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