KR20230076565A - Shrink label film having excellent transparency and printability - Google Patents

Abstract

Disclosed is a shrink label film having improved transparency and visibility, in a shrink label film using a non-adhesive polyolefin material. The present invention provides a shrink label film comprising a skin layer, a core layer, and a seal layer. The skin layer and the seal layer include 70 to 90 parts by weight of a cyclic olefin resin and 10 to 30 parts by weight of linear low-density polyethylene. The core layer includes 5 to 25 parts by weight of a cyclic olefin resin, 60 to 85 parts by weight of a propylene copolymer, and 1 to 20 parts by weight of a modifier.

Description

Shrink label film having excellent transparency and printability {Shrink label film having excellent transparency and printability}

The present invention relates to a film for shrink labels, and more particularly, to a film for shrink labels with excellent transparency and printability.

Labels having a printed layer formed on the outer surface are generally attached to various plastic containers such as PET bottles. Types of these labels include adhesive labels and non-adhesive labels, which are classified according to whether an adhesive is used between the container and the label.

In the case of adhesive labels, they are usually manufactured using polypropylene materials, and in the case of non-adhesive labels, they are mainly manufactured using polystyrene, polyester, polyvinyl chloride, and the like. Labeled containers of polyethylene terephthalate (PET), polystyrene (PS), etc. are pulverized and pelletized after use, and then recycled into containers through a recycling process. At this time, the regeneration process is classified by the difference in specific gravity by putting the pelletized container into water.

On the other hand, the Ministry of Environment implemented the packaging material recycling ease rating standard (Ministry of Environment Notice No. 2019-255, implemented on 19.12.30), and according to this, non-adhesive labels with a specific gravity of less than 1 are classified as the highest recyclability grade. There is a demand for the development of non-adhesive labels below.

Regarding the physical properties of non-adhesive labels, the use of polyolefin materials with a specific gravity of less than 1 can be considered because the specific gravity of existing PS, PET, polyvinyl chloride (PVC), etc. is large, but the polyolefin material film has shrinkage and seaming Since it is difficult to impart properties, a cyclic olefin resin (Cyclic Olefin Copolymer, COC) is added to form the film.

On the other hand, in the case of labels, gravure printing is performed on the produced film. At this time, when the tensile strength of the film is low in the machine direction (MD), the tension on the roll is low, resulting in reduced productivity during printing. . In addition, if the film haze is high during printing, the marketability of the printed product is poor in terms of appearance clarity and aesthetics.

Japanese Patent Registration No. 6268136 discloses a heat-shrinkable multilayer film composed of a front and back layer containing a cyclic olefin-based resin and an ethylene-based resin, and an intermediate layer containing an olefin-based resin and a plastic resin, but the film has a high haze and (MD) Due to its low tensile strength, it is difficult to adjust the tension during printing.

An object of the present invention is to provide a non-adhesive label film having a specific gravity of less than 1 for a shrink label using a polyolefin-based material, while maintaining improved seaming characteristics, noticeability and shrinkage, and improved transparency and printability.

In order to solve the above problems, the present invention is a film for a shrink label comprising a skin layer, a core layer and a seal layer, wherein the skin layer and the seal layer include a cyclic olefin resin, and the core layer is propylene, ethylene or α- 40 to 90 parts by weight of a terpolymer of two olefins selected from olefins; 5 to 30 parts by weight of a petroleum resin having a softening point of 120 to 140 ° C; 5 to 30 parts by weight of polyolefin elastomer;

In addition, the cyclic olefin resin provides a shrink label film, characterized in that the glass transition temperature (Tg) of 60 to 75 ℃.

In addition, the terpolymer has a melting point (Tm) of 123 to 138 ° C and a melt index (230 ° C, 2.16 kg load) of 2 to 10 g / 10 min, and the two olefins are ethylene and 1-butene. It provides a film for a shrink label that does.

In addition, the ethylene and 1-butene are included in the terpolymer in an amount of 1 to 5% by weight, respectively, to provide a shrink label film.

In addition, the polyolefin elastomer is propylene-ethylene rubber (PER) or propylene-butene rubber (PBR) having a density of 0.85 to 0.9 g / cm 3 and a melt index (230 ° C, 2.16 kg load) of 0.5 to 10 g / 10 min Provided is a film for a shrink label characterized in that

In addition, the core layer provides a film for a shrink label characterized in that it further comprises 0.1 to 20 parts by weight of a propylene homopolymer.

In addition, the propylene homopolymer provides a film for shrinkage labels, characterized in that the melt index (230 ℃, 2.16 kg load) is 1 to 10 g / 10min.

In addition, the film has a density of less than 1 g/cm 3 , a shrinkage rate of 40% or more, and a stiffness of 4.5 gf/50 μm or more, measured according to the following method.

[How to measure shrinkage rate]

The film stretched in the transverse direction (TD) is cut into 50 mm × 50 mm in size, immersed in a 100 ° C hot water bath for 10 seconds each, and then the dimensions are measured, and the transverse direction (TD) shrinkage is calculated according to Equation 1 below and expressed as average shrinkage.

[Equation 1]

[Stiffness measurement method]

Using a LOOP STIFFNESS TESTER (TOYOSEIKI), the stretched film is cut into 25 mm × 150 mm size, and the left and right clamps (film fixing device) of the tester are fixed at a distance of 50 mm, and then the outside of both clamps is fixed. After cutting, measure the load (gf) applied when the end of the loop-shaped specimen formed by bending the film so that there is no clamp gap is pushed at a speed of 60 mm/min with a recorder (loading device).

In addition, the film has a haze (ASTM D1003, thickness of 50 μm) of less than 8%, a longitudinal (MD) tensile strength of 250 to 500 kgf / cm 2 measured according to the following method, and a transverse direction (TD) elongation of 30% A shrink label film characterized by the above is provided.

[measurement method]

For the manufactured specimen (ASTM D638 Type IV standard), the longitudinal (MD) tensile strength was measured under the condition of 50 mm/min using a universal testing machine according to ASTM D638, and the film broke under the same conditions as the tensile strength measurement. Measure transverse direction (TD) elongation until

According to the present invention, in the shrink label film including a skin layer, a core layer, and a seal layer, the core layer is composed of propylene terpolymer, petroleum resin, and polyolefin elastomer instead of using conventional linear low-density polyethylene for the skin layer and seal layer. Furthermore, by including a propylene homopolymer, a non-adhesive label having a specific gravity of less than 1 can provide a film for shrinkage labels with improved transparency and printability while maintaining improved seaming characteristics, noticeability and shrinkage.

1 is a schematic diagram for explaining a labeling process (shooting and shrinkage) and a sleeve manufacturing process using a shrink label film.
Figure 2 is a view for explaining the area to check the adhesion of the film in the test example of the present invention.

Hereinafter, the present invention will be described in detail through preferred embodiments. Prior to this, the terms or words used in this specification and claims should not be construed as being limited to the usual or dictionary meaning, and the inventor appropriately uses the concept of the term in order to explain his/her invention in the best way. Based on the principle that it can be defined, it should be interpreted as meaning and concept consistent with the technical spirit of the present invention. Therefore, since the configurations of the embodiments described in this specification are merely the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention, various equivalents and modifications that can replace them at the time of this application It should be understood that there may be

The present invention is a film for a shrink label comprising a skin layer, a core layer and a seal layer, wherein the skin layer and the seal layer include a cyclic olefin resin, and the core layer is composed of two types selected from propylene, ethylene or α-olefin. 40 to 90 parts by weight of a terpolymer with an olefin; 5 to 30 parts by weight of a petroleum resin having a softening point of 120 to 140 ° C; Disclosed is a shrink label film comprising 5 to 30 parts by weight of a polyolefin elastomer.

The present invention provides a non-adhesive label film having a specific gravity of less than 1 for shrinkage labels with improved transparency and printability while maintaining improved seaming characteristics, noticeability and shrinkage.

1 is a schematic diagram for explaining a labeling process (shooting and shrinkage) and a sleeve manufacturing process using a shrink label film. As shown in FIG. 1, the seaming property is an essential physical property for adhesion between films when manufacturing a sleeve, and the notice property is in order to smoothly perform the process of inserting the label into the bottle (shooting process) It is the stiffness (loop stiffness) required for the film over a certain value (about 4.5 gf), the transparency affects the film appearance when printing on the film, and the shrinkage (TD direction) passes through the heat shrink tunnel after label shooting. This is a physical property necessary to adhere the film to the bottle container, etc.

In the present invention, the cyclic olefin resin used in the skin layer and the seal layer is basically a component used to impart shrinkage and seaming of polyolefin materials, and has a glass transition temperature (Tg) of 60 to 75 ° C. It can be used, preferably 62 to 68 ℃ can be used. If the glass transition temperature is less than 60 ° C, low-temperature shrinkage occurs, and when the air temperature rises in summer, the dimensional stability of the shrink label film may deteriorate, and if it exceeds 75 ° C, in the stretching process of the shrink label film manufacturing process Since the stretching temperature in the stretching direction must be high, the heat shrinkability of the film may be lowered.

The cyclic olefin resin includes a cyclic olefin component as a copolymerization component, and is not particularly limited as long as it is a polyolefin containing a cyclic olefin component in its main chain. For example, the cyclic olefin resin is a polymer of a cyclic olefin or a hydrogenated product thereof, It may be a copolymer of α-olefin or a hydrogenated product thereof. Further, these polymers may be grafted and/or copolymerized with an unsaturated compound having a hydrophilic group. These cyclic olefin resins may be used alone or in combination of two or more.

Here, linear low-density polyethylene was mixed with the skin layer and the seal layer in order to lower the specific gravity of the conventional film, but in order to prevent a decrease in transparency due to the linear low-density polyethylene, in the present invention, the skin layer and the seal layer were excluded from the linear low-density polyethylene, and the core The specific gravity of the film satisfies less than 1 through compositional modification of the layer. That is, in the case of conventional films for shrink labels, haze of 10% or more was exhibited when linear low-density polyethylene was included in the skin layer and the seal layer, but transparency could be improved to a haze level of 4.5% or less through exclusion of this.

In the present invention, the core layer lowers the specific gravity of the film to the extent that the improved physical properties are not deteriorated due to the use of the cyclic olefin resin in the skin layer and the seal layer, and propylene in terms of maintaining excellent noticeability, shrinkage and seaming properties of the film, terpolymers of ethylene or two olefins selected from α-olefins; petroleum resin; and polyolefin elastomer; was found to be most suitable.

The terpolymer may preferably be an ethylene-propylene-α-olefin terpolymer, and the α-olefin has 4 to 10 carbon atoms, for example, 1-butene, 1-pentene, 1-hexene, 4-methyl-1 -pentene, 1-heptene, 1-octene, 1-nonene, 1-decene, etc., preferably 1-butene. In the case of the ethylene-propylene-α-olefin terpolymer, the content of ethylene and α-olefin may be 1 to 5% by weight, respectively.

In addition, the terpolymer may preferably have a melting point (Tm) of 123 to 138 ° C and a melt index (230 ° C, 2.16 kg load) of 2 to 10 g / 10 min, more preferably a melting point (Tm) 126 to 135° C. and a melt index (230° C., 2.16 kg load) may be 4 to 8 g/10 min.

In the present invention, the petroleum resin constituting the core layer is a modifier that is mixed to improve the transparency of the film and improve noticeability. The petroleum resin is a light yellow or dark brown thermoplastic resin having a weight average molecular weight of 2,000 g / mol or less obtained by polymerization with an acidic catalyst using higher unsaturated hydrocarbons in high-temperature pyrolysis oil such as naphtha as a raw material. In the present invention, from the viewpoint of improving noticeability A petroleum resin having a softening point of 120 to 140°C, preferably 120 to 130°C may be used.

As a petroleum resin, in the case of aromatic petroleum resin, the main component may be a copolymer of styrenevinyltoluene, α-methylstyrene, and indene. As a resin prepared by, the main component may be a copolymer of isoprene, pipeylene-2-methylbutene-1, and the like. In addition, the aliphatic petroleum resin may include a petroleum resin prepared from dicyclopentadiene as a raw material. In addition, in the case of hydrogenated petroleum resin, it is a resin formed by adding hydrogen to the aromatic petroleum resin and the aliphatic petroleum resin, and may include a petroleum resin prepared from dicyclopentadiene as a raw material and to which hydrogen is added.

In the present invention, the core layer includes polyolefin elastomer (POE) to improve dispersion and flowability through increased compatibility between components and, in particular, to increase transverse direction (TD) elongation. That is, when the shrinkage film has low elongation in the transverse direction (TD), label bursting may occur when applied to product labels such as carbonated drinks, and in the present invention, through mixing of polyolefin elastomer in the core layer, (TD) Elongation can be improved to a level of 50% or more.

Considering this purpose, the polyolefin elastomer may have a density of 0.85 to 0.9 g/cm 3 and a melt index (230° C., 2.16 kg load) of 0.5 to 10 g/10 min, preferably a density of 0.86 to 0.89 g/cm 3 and a melt index (230° C., 2.16 kg load) of 2 to 8 g/10 min.

The polyolefin elastomer may be a copolymer of propylene and an olefin selected from ethylene or α-olefin, and is preferably an ethylene-propylene rubber copolymerized with propylene and 5 to 20% by weight of ethylene, or propylene and 10 to 20% by weight of ethylene. It may be an ethylene-butene rubber copolymerized with 30% by weight of butene, more preferably an ethylene-propylene rubber copolymerized with propylene and 10 to 20% by weight of ethylene.

In the present invention, the core layer improves machine direction (MD) tensile strength by further including a propylene homopolymer. That is, when the tensile strength in the machine direction (MD) is low during printing of the shrink label film, it is difficult to control the roll tension and the printing speed is reduced. By mixing 1 to 10 parts by weight, the printing speed can be improved by improving the tensile strength in the machine direction (MD) of the film.

In addition, considering the purpose of improving the machine direction (MD) tensile strength, the propylene homopolymer may have a melt index (230 ° C., 2.16 kg load) of 1 to 10 g / 10 min, preferably 2 to 5 g / 10 min. can

In the present invention, through a certain range of component content ratios in each layer of the component combination, it is possible to improve transparency and printability while maintaining improved seaming characteristics, noticeability, and shrinkage, which are desired as a film for shrink labels. To this end, the core layer includes 40 to 90 parts by weight of the terpolymer, 5 to 30 parts by weight of the petroleum resin, and 5 to 30 parts by weight of the polyolefin elastomer. Preferably, 50 to 80 parts by weight of the terpolymer, 5 to 25 parts by weight of the petroleum resin, and 10 to 25 parts by weight of the polyolefin elastomer may be included.

When the content of the terpolymer in the core layer is less than 40 parts by weight, transparency decreases during stretching, and when it exceeds 90 parts by weight, shrinkage of the film decreases. In addition, when the petroleum resin content exceeds 30 parts by weight, the shrinkage of the film is reduced. In addition, when the polyolefin elastomer content is less than 10 parts by weight, shrinkage and elongation of the film are reduced, and when it exceeds 30 parts by weight, visibility, transparency and tensile strength of the film are reduced.

On the other hand, in the present invention, flow unevenness may occur due to a difference in viscosity between the cyclic olefin resin and the polyolefin. To solve this problem, the skin layer, the core layer, and the seal layer are formed of a melt blended composition And, a film can be prepared by laminating each composition. Accordingly, it is possible to improve dispersibility through melt kneading before stretching the film due to the difference in flowability of the raw materials of each layer, and to perform a smooth stretching process after forming the film.

The resin composition of each layer constituting the shrink label film according to the present invention may be various additives, such as antioxidants, catalyst neutralizers, pigments, dispersants, weathering agents, antistatic agents, if necessary, as long as the object of the present invention is not impaired. , UV stabilizer, talc, etc. may further contain at least one kind. The amount of each of these additives may be adjusted within a range known to be usable for manufacturing the film for shrinkage labels according to the present invention, taking into account the total production amount and manufacturing process, etc. without affecting the characteristics of the shrink label film according to the present invention.

In the present invention, the preparation of a film using the above components may be performed according to a conventional method known in the art. For example, the ingredients constituting each layer are put into a mixer in the required amount and mixed, and then prepared into pellets at 180 to 240 ° C using an extruder, and melt-molded through a multi-layer film forming machine to form a film. , can manufacture films for shrink labels.

At this time, by using a multi-layer film molding machine, the thickness ratio of the skin layer: core layer: seal layer is, for example, 1: 5 to 10: 0.5 to 1.5, and then molded into a sheet having a thickness of 175 to 200 μm, and then stretched at 80 to 85 ° C. , A film having a final thickness of 50 μm stretched at a stretching ratio of 3.5 to 5 times under conditions of a preheating unit of 95 to 100° C. and a heating unit of 75 to 80° C. can be prepared.

The shrink label film according to the present invention is a non-adhesive label having a specific gravity of less than 1 and can provide a shrink label film with improved transparency and printability while maintaining improved seaming characteristics, noticeability and shrinkage. The shrinkage label film according to has a density of less than 1 g/cm 3 , a shrinkage rate of 40% or more, preferably 45% or more, and a stiffness of 4.5 gf/50 μm or more, preferably 4.5 gf/50 μm or more, preferably Preferably, it may be 5 gf / 50 μm or more, the haze (ASTM D1003, thickness 50 μm) is less than 8%, preferably 4.5 or less, and the tensile strength in the machine direction (MD) measured according to the following method is 250 to 500 kgf / cm 2 , preferably 260 to 400 kgf / cm 2 , and the transverse direction (TD) elongation may be 30% or more, preferably 35% or more.

[How to measure shrinkage rate]

The film stretched in the transverse direction (TD) is cut into 50 mm × 50 mm in size, immersed in a 100 ° C hot water bath for 10 seconds each, and then the dimensions are measured, and the transverse direction (TD) shrinkage is calculated according to Equation 1 below and expressed as average shrinkage.

[Equation 1]

[Stiffness measurement method]

Using a LOOP STIFFNESS TESTER (TOYOSEIKI), the stretched film is cut into 25 mm × 150 mm size, and the left and right clamps (film fixing device) of the tester are fixed at a distance of 50 mm, and then the outside of both clamps is fixed. After cutting, measure the load (gf) applied when the end of the loop-shaped specimen formed by bending the film so that there is no clamp gap is pushed at a speed of 60 mm/min with a recorder (loading device).

[Methods for measuring tensile strength and elongation]

For the manufactured specimen (ASTM D638 Type IV standard), the tensile strength is measured under the condition of 50 mm/min using a universal testing machine according to ASTM D638, and the transverse direction until the film breaks under the same conditions as the tensile strength measurement Directional (TD) elongation is measured.

Hereinafter, the present invention will be described in more detail through specific examples and comparative examples. The component specifications used in Examples and Comparative Examples are summarized in Table 1 below, and the physical property measurement method is as follows.

[measurement method]

- Density: measured according to the ASTM D 1505 density gradient method.

- Melt index: measured under the condition of a load of 2.16 kg at 190 ° C or 230 ° C according to ASTM D1238 standard.

- Melting point (Tm): measured according to ASTM D3418 standard. After pre-melting 10 mg of the test piece at 220° C. for 5 minutes in a nitrogen gas atmosphere using a differential scanning calorimeter (DSC, TA Instruments), the temperature was lowered to 40° C. at a deceleration rate of 10° C./min. Thereafter, the temperature was raised at a heating rate of 10°C/min, and the peak temperature of the maximum peak of the obtained melting endotherm curve was defined as the melting point (Tm).

- Glass transition temperature (Tg): measured according to ASTM D3418 standard. After pre-melting 10 mg of the test piece for 5 minutes at 220 ° C. in a nitrogen gas atmosphere using a differential scanning calorimeter (DSC, TA Instruments), the temperature was lowered to -80 ° C. at a cooling rate of 10 ° C./min. After that, while raising the temperature at a heating rate of 10 °C/min, the middle value of the height between the start point and the end point of the glass transition was calculated and defined as the glass transition temperature (Tg).

- Softening point (VICAT): measured according to the ASTM D1525 standard (ASTM E28 standard in the case of petroleum resin). As a penetration test, a load of 1 kg or 5 kg is applied to a specimen with a thickness of 3 mm, and the temperature is raised uniformly at a rate of 50 °C/hr. The softening point is the temperature when a standard needle with a surface area of 1 ㎟ penetrates 1 mm defined as

division ingredient Grade density
(g/cm) MI (g/10min) Thermal analysis result 190℃ 230℃ Tm(℃) Tg(℃) Softening point (℃) skin layer
/ seal layer COC 9506F-500 1.010 0.9 5.5 - 65 - LLD XP9200EN 0.917 1.0 - 116 - 106 core layer T-PP1 SB-740D 0.900 - 5.5 129 - 114 T-PP2 SFI-553 0.900 - 7.0 132 - 118 H-PP FO-130X 0.900 - 3.0 - - - HC SU525 1.080 - - - - 125 PER 6102FL 0.862 1.4 3.0 - - 53 PBR XM-7070 0.884 3.0 7.0 - - 67 * main
- COC: Cyclic Olefin Resin
- LLD : Linear Low Density Polyethylene
- T-PP1: Propylene terpolymer (including 3.2% by weight of ethylene and 4.5% by weight of 1-butene)
- T-PP2: Propylene terpolymer (including 3.2% by weight of ethylene and 3.5% by weight of 1-butene)
- H-PP : Propylene Homopolymer
- HC: petroleum resin
- PER: Propylene-ethylene rubber (including 16% by weight of ethylene)
- PBR : Propylene-butene rubber (including 26% by weight of butene)

Examples and Comparative Examples

After preparing a melt blend (using a twin-screw extruder) for each layer with the composition shown in Table 2 below, the thickness ratio of the skin layer, core layer, and seal layer was 1:8: It is composed of 1 or 1.5:7:1.5 and formed into a sheet with a thickness of 175 to 200 ㎛, and then stretched at a draw ratio of 3.8 to 4.8 times under the conditions of 80 to 85 ℃ in the stretching part, 98 ℃ in the preheating part and 78 ℃ in the heating part, so that the final thickness is 50 ㎛ A film of was prepared.

test example

The physical properties of the prepared film were measured by the following method, and the results are shown in Table 2 below.

[Method of measuring physical properties]

-Shrinkage rate: A film stretched in the transverse direction (TD) is cut into 50 mm × 50 mm in size, immersed in a 100 ° C hot water bath for 10 seconds each, and then the dimensions are measured, and the transverse direction (TD) according to Equation 1 below Shrinkage was calculated and expressed as the average shrinkage.

[Equation 1]

- Seaming: Solvent (toluene, chloroform, limonene or alpha-pinene) was applied to a cotton swab to confirm adhesion between the outer and back surfaces of the stretched film (see Fig. 2).

- Haze: Measured according to ASTM D1003 standard.

- Loop-stiffness: Using a LOOP STIFFNESS TESTER (TOYOSEIKI), the stretched film is cut into 25 mm × 150 mm size, and the left and right clamps (film fixing device) of the tester are fixed at a distance of 50 mm, and both clamps The part outside of was measured for the load (gf) applied when the end of the loop-shaped specimen formed by bending the film so that there was no clamp gap after cutting was pushed at a speed of 60 mm/min with a recorder (loading device).

- Tensile strength and elongation: Measure the tensile strength in the machine direction (MD) under the condition of 50 mm/min using a universal testing machine according to ASTM D638 for the manufactured specimen (ASTM D638 Type IV standard), and measure the tensile strength and Transverse direction (TD) elongation until the film breaks under the same conditions was measured.

division ingredient Comparative Example 1 Comparative Example 2 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 skin
/ seal layer
(parts by weight) COC 70 70 100 100 100 100 100 100 100 100 100 LLD 30 30 - - - - - - - - - core layer
(parts by weight) T-PP1 65 - 65 60 65 70 60 60 - 60 - T-PP2 - 65 - - - - - - 65 - 65 H-PP - - - - 5 5 5 5 - 5 5 HC 20 20 20 20 15 10 20 15 15 15 15 PER - - - - - - 15 20 20 20 20 PBR 15 15 15 15 15 15 - - - - - film thickness ratio Skin/seal layer 2 2 2 2 2 2 2 2 2 3 3 core layer 8 8 8 8 8 8 8 8 8 7 7 film
Properties density
(g/cm) 0.93 0.93 0.94 0.941 0.932 0.926 0.93 0.92 0.921 0.925 0.926 Haze
(%) 12.5 13.5 4.5 4.3 4.8 5 4 4.5 4.8 4.2 4.5 Loof Stiffness (gf/50㎛) 5 5.5 5.6 5.8 5.4 5.1 5.6 5.3 5.5 5.7 5.9 Seaming O O O O O O O O O O O Tensile strength (kgf/㎠) 250 280 260 290 250 248 285 265 275 290 300 Elongation (%) 28 28 25 29 30 32 35 42 40 41 40 Shrinkage (%) 55 52 57 58 48 48 50 52 48 55 52

Referring to Table 2, according to the present invention, when a cyclic olefin resin is applied to the skin layer and the seal layer, and the core layer is composed of a propylene terpolymer, a petroleum resin, and a polyolefin elastomer, generally good shrinkage properties, seaming properties, and noticeability are obtained. While maintaining, transparency and tensile strength are improved, however, when PER is used as a polyolefin elastomer in the core layer (Examples 5 to 9) or a propylene homopolymer is further mixed (Examples 2 to 6, 8 and 9 ), it can be seen that this effect is significantly improved.

In contrast, when linear low-density polyethylene is mixed with the skin layer and the seal layer (Comparative Examples 1 and 2), it can be seen that the transparency is significantly lowered and the elongation is also slightly lowered.

Above, preferred embodiments of the present invention have been described in detail. The description of the present invention is for illustrative purposes, and those skilled in the art will understand that other specific forms can be easily modified without changing the technical spirit or essential features of the present invention.

Therefore, the scope of the present invention is indicated by the following claims rather than the above detailed description, and all changes or modifications derived from the meaning, scope and equivalent concept of the claims are included in the scope of the present invention. should be interpreted

Claims (10)

A film for a shrink label comprising a skin layer, a core layer and a seal layer,
The skin layer and the seal layer include a cyclic olefin resin,
The core layer includes 40 to 90 parts by weight of a terpolymer of propylene and two olefins selected from ethylene or α-olefin; 5 to 30 parts by weight of a petroleum resin having a softening point of 120 to 140 ° C; 5 to 30 parts by weight of a polyolefin elastomer; a film for a shrink label comprising: According to claim 1,
The cyclic olefin resin has a glass transition temperature (Tg) of 60 to 75 ° C. According to claim 1,
The film for shrink labels, characterized in that the skin layer and the seal layer do not contain linear low-density polyethylene. According to claim 1,
The terpolymer has a melting point (Tm) of 123 to 138 ° C and a melt index (230 ° C, 2.16 kg load) of 2 to 10 g / 10 min, and the two olefins are ethylene and 1-butene, characterized in that Film for shrink labels. According to claim 1,
The film for shrinkage labels, characterized in that the ethylene and 1-butene are contained in 1 to 5% by weight, respectively, in the terpolymer. According to claim 1,
The polyolefin elastomer is propylene-ethylene rubber (PER) or propylene-butene rubber (PBR) having a density of 0.85 to 0.9 g / cm 3 and a melt index (230 ° C, 2.16 kg load) of 0.5 to 10 g / 10 min. Film for shrink labels made of According to claim 1,
The film for shrinkage labels, characterized in that the core layer further comprises 0.1 to 20 parts by weight of a propylene homopolymer. According to claim 7,
The film for shrinkage labels, characterized in that the melt index (230 ℃, 2.16 kg load) of the propylene homopolymer is 1 to 10 g / 10min. According to claim 1,
The film has a density of less than 1 g/cm 3 , a shrinkage rate of 40% or more, and a stiffness of 4.5 gf/50 μm or more, measured according to the following method:
[How to measure shrinkage rate]
The film stretched in the transverse direction (TD) is cut into 50 mm × 50 mm in size, immersed in a 100 ° C hot water bath for 10 seconds each, and then the dimensions are measured, and the transverse direction (TD) shrinkage is calculated according to Equation 1 below and expressed as average shrinkage.
[Equation 1]

[Stiffness measurement method]
Using a LOOP STIFFNESS TESTER (TOYOSEIKI), the stretched film is cut into 25 mm × 150 mm size, and the left and right clamps (film fixing device) of the tester are fixed at a distance of 50 mm, and then the outside of both clamps is fixed. After cutting, measure the load (gf) applied when the end of the loop-shaped specimen formed by bending the film so that there is no clamp gap is pushed at a speed of 60 mm/min with a recorder (loading device). According to claim 9,
The film has a haze (ASTM D1003, thickness 50 μm) of less than 8%, a machine direction (MD) tensile strength of 250 to 500 kgf / cm 2 and a transverse direction (TD) elongation of 30% or more, measured according to the following method Film for shrink labels, characterized in that:
[measurement method]
For the manufactured specimen (ASTM D638 Type IV standard), the longitudinal (MD) tensile strength was measured under the condition of 50 mm/min using a universal testing machine according to ASTM D638, and the film broke under the same conditions as the tensile strength measurement. Measure transverse direction (TD) elongation until

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