KR20140127595A

KR20140127595A - Heat Shrinkable Film for Label with Low Specific Gravity and Process of Preparing Same

Info

Publication number: KR20140127595A
Application number: KR1020130046137A
Authority: KR
Inventors: 오원석; 오영택
Original assignee: 동일화학공업 주식회사
Priority date: 2013-04-25
Filing date: 2013-04-25
Publication date: 2014-11-04

Abstract

The heat shrinkable film for label according to the present invention comprises a foam layer 10 mainly composed of polystyrene and a pair of non-foam layers 20 melt-bonded to both sides of the foam layer 10, And the pair of non-foam layers 20 are co-extruded to have a low specific gravity. The heat shrinkable film for label according to the present invention is prepared by coextruding each raw material so that a foam layer 10 composed mainly of polystyrene and a pair of non-foam layers 20 melt-adhered to both sides of the foam layer 10 are formed To prepare an unstretched film, and stretching the unstretched film in the TD (transverse direction) direction. The foam layer 10 is preferably foamed at a foaming ratio in the range of 5 to 20%. It is preferable that the thickness of the foam layer 10 is in the range of 60 to 90% with respect to the thickness of the entire film and the thickness of the pair of non-foam layers 20 is in the range of 5 to 20% with respect to the thickness of the entire film. The heat shrinkable film for labels of the present invention preferably has a specific gravity of 0.9 to less than 1.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat shrinkable film for a label having a low specific gravity,

The present invention relates to a heat shrinkable film used for forming a label on the outer periphery of various containers such as a plastic container, a glass bottle, an aluminum can and the like. More particularly, the present invention relates to a heat shrinkable film suitable for use as a labeling film for various containers and having a low specific gravity to facilitate water separation, and a method for producing the same.

The heat shrinkable film is used for a label formed to surround the outer periphery of a container such as various synthetic resin containers such as a bottle of polyester (PET), a glass bottle, an aluminum can and the like (hereinafter referred to as a container). That is, the contents necessary for a heat shrinkable film for a label are printed, the printed film is attached to the container in a cylindrical shape (called tubing or seaming), and hot air is applied from outside to adhere to the outer periphery of the container .

The heat shrinkable film for labels to be wrapped around the outer periphery of the container by heat shrinkage must meet various physical properties in consideration of the label manufacturing process, quality or appearance. Such physical properties include heat resistance, printability, gloss, transparency, adhesiveness, shrinkability, and the like.

Among the synthetic resin films known so far, PVC films have been found to be most suitable as heat shrinkable films for labels. PVC films have been widely used as heat-shrinkable films for labels because properties such as heat resistance, printability, gloss, transparency, adhesiveness, and stretchability are suitable for labels. PVC films, however, contain fatal defects in environmental pollution because they produce environmental hormones during disposal after use. Therefore, Korea and Taiwan are already regulating the use of PVC film as a label, and other developed countries are prohibiting their use through laws or autonomous regulations.

PET films and PS films were developed to replace PVC films for labels. PET film or PS film has no environmental pollution problem like PVC film, and can be easily recovered or regenerated, but there are also a few problems that must be overcome for use for labeling.

The PET film has good heat resistance, printability and adhesiveness, but it has a specific gravity of about 1.35, which causes a rise in production cost and has the disadvantage that overshrinkage occurs during heat shrinkage. When shrinkage occurs, the glass bottle or aluminum cans are not affected. However, in the case of a plastic container, the container is distorted or deformed. Since the PET film has good heat resistance, it can be used even when it is required to be sterilized at a high temperature of 98 캜, such as fruit juice.

On the other hand, the PS film is advantageous in that it has good low-temperature shrinkability, light weight of about 1.05 and light shrinkage. Because of its good low-temperature shrinkability, it is suitable for use as a label for containers of milk products such as milk and yogurt. Since the specific gravity is light, the manufacturing cost can be reduced, and since the shrinkage does not occur, a beautiful appearance can be maintained after the heat shrinkage. However, since the PS film uses an alcohol-based solvent without using toluene or benzene in the printing process, the PS film is good in environmental properties. However, since the printing property is difficult, there is a problem in that a good ink for printing has to be appropriately selected or developed.

In order to solve the above problems, the present applicant has developed a heat-shrinkable film for labels and has been patented in Korean Patents Nos. 926716 and 1156607, and has filed a patent application in Patent Application No. 2012-25974.

The heat shrinkable film for a label of Japanese Patent No. 926716 has a three-layer structure in which a PS film layer is an intermediate layer and a PET film layer is bonded to both sides of the PS film film layer. The three- It is suitable for use as a film for labeling because all properties such as gloss, transparency, adhesiveness and stretchability are good.

The heat shrinkable film for a label of Japanese Patent No. 1156607 has a structure in which a PS film layer having a specific structural formula is an intermediate layer and a PET film layer having a specific structural formula is bonded to both sides of the intermediate layer, Provided is a film for labels which has good low-temperature shrinkability and does not cause excessive shrinkage.

A PS film layer having a specific structural formula of Patent Application No. 2012-25974, and a PET film layer having a specific structural formula, and a heat shrinkage for a new label which can prevent peeling of the film even when printing is performed at 5 degrees or more Lt; / RTI > film.

However, although the above-mentioned label film is applied to the container, it has been difficult to recover the container for recycling due to the label. For example, almost all containers are made of PET. In order to recycle a PET container, it is necessary to shrink the container and remove the attached label. The reason for removing the label is that the label usually contains a PS component, so that its components are different from those of PET, and since the label is printed with various color inks, it causes contamination when mixed with a transparent PET container, When the PET container is recycled, the value of the product drops. For this reason, the Korean government also encourages the development of labeling films that are easy to remove and discard labels and to facilitate the separation of water in order to efficiently recover PET containers.

When the PET container with label is crushed and separated by water, the specific gravity of PET is usually about 1.35, so that the shattered PET pieces sink downward. If the specific gravity of the label is less than 1, the shattered label will float on the water The shredded label can be easily removed and separated. By doing so, PET pieces that settle down can be easily recovered and recycled. In order to separate the salt from the brine, it is necessary to wash the brine with the brine again.

The heat shrinkable film for labels having a low specific gravity of the present invention has been developed under the above-mentioned object, and the specific gravity is smaller than 1 to develop a film for labeling on water. The PET bottle in which the film of the present invention is used as a label is recovered and cut to a suitable size in a cutter. When a piece of cut PET bottle is put into the water, the PET bottle piece sinks down and the label film floats on the water. Discard the label film on the water, discard it, and collect the recycled PET pieces.

An object of the present invention is to provide a film for labeling which floats on water by having a specific gravity smaller than one.

Another object of the present invention is to provide a film for labels floating on water having a specific gravity in the range of 0.9 to less than 1.

It is still another object of the present invention to provide a film for a label which satisfies all of the physical properties as heat-shrinkable films for labels such as heat resistance, printability, gloss, transparency, adhesiveness, will be.

Another object of the present invention is to provide a film for label which can facilitate water separation by making the specific gravity smaller than 1.

Another object of the present invention is to provide a labeling film that can reduce the manufacturing cost by using less raw materials and meet the weighting ratio reduction ratio required in the national policy of the world.

The above and other objects of the present invention can be achieved by the present invention described below.

The heat shrinkable film for label according to the present invention comprises a foam layer 10 mainly composed of polystyrene and a pair of non-foam layers 20 melt-bonded to both sides of the foam layer 10, And the pair of non-foam layers 20 are co-extruded to have a low specific gravity.

The heat shrinkable film for labels according to the present invention is produced by co-extruding each raw material so as to form a non-foam layer 20 on both sides of a foamed intermediate layer 10 having polystyrene as a main component, thereby forming an unstretched film, And stretched in the transverse direction (TD) direction.

The foam layer 10 is preferably foamed at a foaming ratio in the range of 5 to 20%.

It is preferable that the thickness of the foam layer 10 is in the range of 60 to 90% with respect to the thickness of the entire film and the thickness of the pair of non-foam layers 20 is in the range of 5 to 20% with respect to the thickness of the entire film.

The heat shrinkable film for labels of the present invention preferably has a specific gravity of 0.9 to less than 1.

The heat shrinkable film for label of the present invention preferably has a thickness in the range of 30 to 60 mu m, but is not limited thereto.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The present invention relates to a labeling film which floats on water by setting a specific gravity to be smaller than 1, and is characterized by satisfying all the properties as a heat-shrinkable film for labels such as heat resistance, printability, gloss, transparency, adhesiveness, Shrinkable film for labels, which can reduce the production cost by using a low specific gravity to facilitate water separation and further reduce the amount of raw materials and meet the policy of reduction in weight.

FIG. 1 is a schematic cross-sectional view of a heat shrinkable film having a three-layer structure according to the present invention.

The present invention relates to a heat shrinkable film used for forming a label on the periphery of a synthetic resin container, particularly a PET bottle container, and is suitable for use as a labeling film for various containers and has a low specific gravity The present invention relates to a heat shrinkable film. FIG. 1 is a schematic cross-sectional view of a heat shrinkable film having a three-layer structure according to the present invention.

In the present invention, the foam layer 10 should be located in the middle layer, that is, inside the film. In other words, a pair of non-foam layers 20 are melt-bonded to both sides of the foam layer to form a three-layer structure. The reason that the foam layer 10 is located inside the film and the non-foam layer 20 is located in the skin layer is that the contents necessary for the non-foam layer as the skin layer must be printed. Since the foamed layer 10 foamed with polystyrene as a main component is not uniform in its surface, good printing quality can not be maintained when printing. However, since the surface of the non-foam layer 20 is uniform, good printing can be performed.

Of course, the heat shrinkable film for label of the present invention may be composed of a foam layer 10 mainly composed of polystyrene and a non-foam layer 20 melt-bonded to one side of the foam layer 10. In this case, the surface of the non-foam layer should be printed. The above-mentioned three-layered film can be printed on any surface because both surfaces are non-foamed layers.

The reason for forming the foam layer as the intermediate layer of the film in the present invention is to reduce the specific gravity. In the present invention, it is preferable that the specific gravity of the film is in the range of about 0.9 to less than 1. For this purpose, the foam layer 10 is preferably foamed at a foaming ratio in the range of 5 to 20%. The larger the expansion ratio, the smaller the specific gravity. However, since the heat-shrinkable film for label is shrunk and then adhered to the outer periphery of the container, the shrinkage ratio should be good. However, if the foaming rate of the foam layer 10 exceeds 20%, the shrinkage ratio decreases, and therefore, it can not be applied to general containers. On the other hand, if the expansion ratio of the foam layer 10 is less than 5%, the specific gravity increases, and the specific gravity of about 0.9 to less than 1 required in the present invention can not be obtained.

In one embodiment of the invention, the thickness of the foam layer 10 is in the range of 60 to 90% with respect to the thickness t of the total film, and the thickness of the pair of non- To 5% and 20%, respectively. The heat shrinkable film for label of the present invention preferably has a thickness in the range of about 30 to 60 mu m, but is not limited thereto.

The heat shrinkable film for label according to the present invention is prepared by coextruding each raw material so that a foam layer 10 composed mainly of polystyrene and a pair of non-foam layers 20 melt-adhered to both sides of the foam layer 10 are formed To prepare an unstretched film, and stretching the unstretched film in the TD (transverse direction) direction.

The heat-shrinkable film of the present invention mainly comprises polystyrene. The foam layer 10 co-extrudes a pair of non-foam layers 20 on both sides while foaming using a foaming agent. Such a technique of co-extruding a film into a three-layer structure can be easily carried out by a person skilled in the art to which the present invention belongs.

The polystyrene resins used in the present invention are various. The polystyrene resin is transparent and has good workability, but has a weak impact strength. Therefore, polystyrene copolymerized by adding a rubber component such as butadiene can be preferably used.

The foaming agent used for forming the foam layer 10 is preferably used in an amount of 0.01 to 1.0 wt% based on the polystyrene resin. Since the amount of the foaming agent used is directly related to the foaming ratio, The amount of the foaming agent can be appropriately increased or decreased in consideration of the rate.

The foaming agent used in the present invention includes organic and inorganic foaming agents. Representative commercially available examples include azodicarbonamide, p, p'-oxybis (benzene sulfonyl hydrazide), p-tolune sulfonyl hydrazide sulfonyl hydrazide, p-toluene sulfonyl acetone hydrazone, N, N'-dinitrosopentamethylene tertamine, p-toluenesulfonyl semi- P-tolune sulfonyl semicarbazide, 5-phenyltertazole, sodium bicarbonate, and the like.

The foam layer 10 has a microscopic structure in which cells containing air bubbles are uniformly formed. The cells are small and uniformly distributed so that a high quality foam film can be produced. The blowing agent should be able to generate the gas uniformly during the extrusion process so that small cells are uniformly distributed. The foaming agent is mixed with the polystyrene resin, heated, and then extruded into a molten state.

The unstretched film produced by co-extrusion is produced by stretching in the transverse direction (TD) direction. The reason why the unstretched film is stretched in the TD direction is to give a shrinkage ratio. The undrawn film is preferably stretched at an elongation of about 2 to 5 times in the TD direction. When the width of the non-stretched film is usually 750 mm, stretching is preferably performed at a width of about 2,500 mm to 3,500 mm. If necessary, it may be stretched by a two-step stretching method. The two-step stretching method is described in detail in Patent No. 741935 of the present applicant.

In one embodiment of the invention, the thickness of the foam layer 10 is about 80% of the thickness of the total film, the thickness of one non-foam layer 20 is about 10% of the thickness of the total film, Is set at 15%, a labeling film having a specific gravity of about 0.9 to less than 1, which is required in the present invention, can be obtained. The heat shrinkable film for label of the present invention preferably has a thickness in the range of about 30 to 60 mu m, but is not limited thereto.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

10: foam layer 20: a pair of non-foam layers
t: Film thickness

Claims

A foam layer 10 composed mainly of polystyrene and a pair of non-foam layers 20 melt-adhered to both sides of the foam layer 10, wherein the foam layer 10 and the pair of non- 20) is co-extruded to have a low specific gravity.
2. The method of claim 1, wherein the foam layer (10) has a thickness in the range of 60 to 90% relative to the total film, and the pair of non-foam layers (20) And a heat shrinkable film for a label.
The heat shrinkable film for labels according to claim 1, wherein the foam layer (10) is foamed at a foaming ratio ranging from 5 to 20%.
The heat shrinkable film for labels according to any one of claims 1 to 3, wherein the thickness of the film is in the range of 30 to 60 mu m.
The heat shrinkable film for labels according to claim 4, wherein the butadiene rubber component is copolymerized with the polystyrene.
The heat shrinkable film for labels according to claim 5, wherein the specific gravity of the film is in the range of 0.9 to less than 1.
Extruding each raw material so as to form a foam layer 10 comprising polystyrene as a main component and a pair of non-foam layers 20 melt-adhered to both sides of the foam layer 10 to produce an unstretched film; And
Stretching the unstretched film in the transverse direction (TD) direction;
Wherein the heat shrinkable film has a low specific gravity.
The method of manufacturing a heat shrinkable film for labels according to claim 7, wherein the unstretched film is stretched at an elongation of 2 to 5 times in the TD direction.
8. The method of claim 7, wherein the foam layer (10) has a thickness in the range of 60 to 90% of the total film, and the pair of non-foam layers (20) Wherein the thermally shrinkable film has a thickness of 100 탆 or less.
The method according to claim 7, wherein the foam layer (10) is foamed at a foaming ratio ranging from 5 to 20%.
11. The method according to any one of claims 7 to 10, wherein the thickness of the film is in the range of 30 to 60 占 퐉.
12. The method of claim 11, wherein the butadiene rubber component is copolymerized with the polystyrene.
The method for producing a heat shrinkable film for label according to claim 12, wherein the specific gravity of the film is 0.9 to less than 1.
Use of a heat shrinkable film according to any one of claims 1 to 6 for labeling.