JPH09274439A - Stretch label - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an all-purpose stretch label having excellent flexibility and stretching property, enough heat resistance and strength and excellent transparency. SOLUTION: The label consists of a transparent film prepared by forming a film of a linear low density polyethylene or layers of this polyethylene and a olefin resin and rapidly cooling, and the film has <=7% haze value. The low density polyethylene is obtd. by copolymer. of ethylene and olefin having >=6 carbon number in the presence of a single cite catalyst and has 0.910 to 0.930g/cm<3> density and 1.0 to 4.0g/10min melt index. The single cite catalyst is preferably a metallocene catalyst.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stretch label attached to various containers such as cans such as aluminum cans and steel cans, plastic containers such as PET bottles, bottles such as glass bottles and ceramics.

[0002]

2. Description of the Related Art A stretch label is made of a film-shaped synthetic resin elastic cylinder, which is expanded and held, and a predetermined article is placed therein, and then the expansion of the cylinder is cancelled. It is used to adhere the cylinder to the outside of the article by utilizing the elasticity of the body, and its material is a polyethylene resin film having self-stretchability, especially low density polyethylene, particularly linear low density Polyethylene is often used. However, as this linear low-density polyethylene, one obtained by polymerization using a multi-site type catalyst such as Ziegler catalyst is used (for example, JP-A-58-144883), and this is a comonomer (butene, (Hexene, octene, etc.) units are non-uniformly distributed, and a part with a very small amount of comonomer units is generated, and this part is easy to crystallize, so it is not a factor that hinders the flexibility and stretchability necessary for stretch labels. Absent.

On the other hand, not only linear low-density polyethylene, but also softer low-density polyethylene is not sufficiently flexible and inferior in residual strain, so that a more elastic ethylene-vinyl acetate copolymer (vinyl acetate) is used. Content 3-8%
However, the strength of this material is weak, and in particular, the surface is apt to be rubbed and torn, and the piercing strength is inferior and the heat resistance is inferior.

[0004]

SUMMARY OF THE INVENTION The present invention overcomes the disadvantages of such conventional stretch labels and provides flexibility,
The purpose of the present invention is to provide a versatile stretch label which is excellent in elasticity, has sufficient heat resistance and strength, and is excellent in transparency.

[0005]

As a result of various studies to develop a stretch label having the above-mentioned preferable characteristics, the present inventors have found that a single-site catalyst, particularly a metallocene catalyst, is used as a linear low density polyethylene. Stretch a transparent film of a specific haze value prepared by polymerizing and using a specific density and melt index, and then discharging this from a molding machine in a molten or heated state and rapidly cooling after film formation It was found that the purpose can be achieved by using a label material, and the present invention has been completed based on this finding.

That is, according to the present invention, ethylene and 6 carbon atoms are used.
Density 0.910 to 0.930 g / cm ³ obtained by copolymerizing the above olefins with a single-site catalyst.
And a linear low-density polyethylene having a melt index of 1.0 to 4.0 g / 10 minutes or a layered product of the polyethylene and an olefin resin, which is prepared by rapid cooling and has a haze value of 7% or less. A stretch label mainly composed of a film is provided. In the present invention, the term “mainly composed of a transparent film” means that the transparent film is used alone or that a plurality of materials mainly composed of the transparent film are used.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

As a material for the stretch label of the present invention, a haze value prepared by forming a film of a specific linear low density polyethylene (hereinafter referred to as LLDPE) or a layered product of the polyethylene and an olefin resin, followed by rapid cooling. A transparent film of 7% or less is used.

This LLDPE is obtained by copolymerizing ethylene and an olefin having 6 or more carbon atoms using a single site catalyst, and has a density of 0.910 to 0.930 g / cm ^3, preferably 0.915 to 0.930 g. / Cm ³ and melt index 1.0 to 4.0 g / 10 minutes, preferably 1.
Those having a density of 0.915 to 0.930 g / cm ³ and a melt index of 1.3 to 2.0 g / 10 minutes are advantageous. is there. If the density is too high, the elastic recovery force is small and the residual elongation is large, and if it is too low, the slipperiness is deteriorated and smooth labeling is inevitable. This residual elongation can be expressed by the residual strain rate.
About the stretch label prepared from LDPE, 10
The residual strain rate after applying a load of% elongation and no load is 1% or less, preferably 0.8% or less, and after applying a load of 20%, the residual strain rate is no load. It is preferable that the rate is 2% or less, preferably 1.6% or less. If the melt index (MI) is too low, the melt viscosity will increase, and the molding machine will be overloaded during molding, making it difficult to mold, and if it is too high, the film strength will be low and molding stability will tend to be impaired. I cannot escape. This L
The commercially available LDPE is Evolution SP
2520, Evolution SP2020 (both manufactured by Mitsui Petrochemical Co., Ltd.) and the like.

Examples of the olefin used as a comonomer in the above copolymerization include 1-hexene and 1-hexene.
Examples thereof include octene, 4-methyl-1-pentene, and 1-decene. Among them, 1-hexene and 1-octene are preferable.

Examples of the single-site catalyst used as a polymerization catalyst for this copolymerization include metallocene catalysts,
Titanocene dichloride-organoaluminium halide catalyst, titanium alcoholate-organoaluminum halide catalyst, vanadium chloride-organoaluminum halide catalyst,
Acetylacetonatochromium-organoaluminum halide catalysts and the like can be mentioned, and among them, metallocene catalysts are preferable. Examples of the metallocene catalyst include a metallocene-alumoxane catalyst (eg, US Pat. No. 4,701,432), a reaction product of a Group IV-B metal metallocene compound and a specific ionic activator compound. Catalyst (eg, EP Publication 277,034, JP-T-5-50)
2906), a metallocene compound and Ti, Mg,
A catalyst containing a halogen and a solid titanium catalyst component containing a compound having a specific ether bond (JP-A-3-294)
305), metallocene compounds and groups I to II.
It comprises an organometallic compound containing a Group I metal preliminarily polymerized with ethylene and a polyene compound, an organometallic compound containing a Group I to Group III metal, and an electron donor used as necessary. Catalyst (JP-A-5-222122)
Publication).

The transparent film used as the material of the stretch label of the present invention is prepared by forming the layered product of the above-mentioned LLDPE or this product and the olefin resin and then quenching. For this film formation, for example, extrusion molding using a T-die, extrusion molding using an annular die, inflation molding, calender molding, and the like are used, and among these, inflation molding and T-die extrusion molding are preferably used. The film formation of the layered product is usually carried out by coextrusion, preferably as an olefin resin as a constituent component of the layered product,
At least one of ethylene-vinyl acetate copolymer, high-pressure low-density polyethylene and linear low-density polyethylene polymerized using a multi-site type catalyst, or at least one of them and a single-site catalyst Examples thereof include blends with linear low-density polyethylene copolymerized with each other, or resins containing at least one of them as a main component. At the time of molding, a small amount of an additive such as an antioxidant such as a phenolic compound, a slip agent such as ethylene bisamide or erucic acid amide, an antiblocking agent such as silica powder, or the like may be added to the LLDPE or the layered material. it can.

[0012] The film is usually cooled immediately after the film formation by 1
After 0 seconds, it is carried out so as to reach a temperature of 80 ° C. or lower, preferably 50 ° C. or lower and solidify, and preferably by a water cooling method. As the water-cooling method, it is preferable to use an air knife or the like to bring it into close contact with a cooling metal roll at 30 to 40 ° C. for cooling. This quenching improves transparency. Regardless of this, slow cooling inevitably causes an excessive haze value and impairs transparency.

The transparent film thus obtained is
If necessary, a thin layer may be provided on one or both sides for improving printability and characteristics such as dirt adhesion, or may be printed, cut into the required label width, and then bonded or heat-sealed into a tubular shape. Is processed into a desired stretch label. For this adhesion, an epoxy-based or urethane-based adhesive, particularly a two-component reactive adhesive is preferably used.

When the transparent film is a printed film or a printable or writable film, it is desirable that at least one surface of the film is subjected to an activation process such as a corona discharge process, and the extent thereof is The wetting index after 2 weeks from the treatment is adjusted to be 37 dyn / cm or more. Here, the wetting index is obtained according to JIS-K-6768.

The stretch label of the present invention is usually 30-
It is formed into a film having a thickness of 120 μm, preferably 40 to 100 μm.

The stretch label of the present invention is adjusted to have specifications which can be adapted to the material and shape of the container and the purpose of use. For example, the stretch label of the present invention can easily follow the rigidity of the container by adjusting the material, the film thickness, and the like. Workability at the time of labeling with the stretch label of the present invention can also be improved by adjusting the material, the film thickness, and the like.

The adhesion of the stretch label of the present invention to a container can be enhanced by using a material suitable for the material of the container.

As the material of the container to which the stretch label of the present invention is applied, polyester, polyvinyl chloride, polystyrene, AS resin, polyacrylonitrile, polyamide / polyolefin composite material such as nylon / polyethylene, and ethylene-vinyl acetate based copolymer are used. Examples include olefin-vinyl ester copolymers such as polymers, ethylene-vinyl acetate copolymer / polyethylene composites, polymers such as polyolefin, glass, and ceramics.

[0019]

Next, the present invention will be described in more detail by way of examples.

The physical properties of the stretch label stocks in Examples and Comparative Examples were determined as follows. (1) Haze value: determined based on JIS-K-7105. (2) Young's modulus: Obtained based on JIS-P-7118. (3) Residual strain rate: Using a tensile tester (autograph) manufactured by Shimadzu Corporation, a film-shaped stretch label raw sheet having a width of 20 mm was attached between chucks with a distance between chucks of 100 mm without bending, and then a cloth was crossed. The distance between the chucks is expanded at a head speed of 100 mm / min to extend the original fabric by 5% or 10%, and the stretched state is allowed to stand for 5 seconds. Then, the distance between the chucks is returned to 100 mm, and one minute later, a film test is conducted. The length (X) (mm) of the piece was measured and calculated by the following formula. Residual strain rate (%) = [(X-100) / 100] × 10
0 (4) Strength: The following test was conducted using a test machine obtained by modifying the friction coefficient test machine. A 60μ thick stretch label roll was fixed on the test table, and the same stretch label roll was also attached to the back side of the sliding piece with a load of 100g / cm ² ,
It was pulled at a speed of 100 mm / min, and the degree of presence or absence of rubbing was evaluated according to the following criteria. ◯: No rubbing and tearing △: Rubbing and tearing partly ×: Rubbing and tearing is considerable

Example 1 Evolution SP2520 [trade name, manufactured by Mitsui Petrochemical Co., Ltd., LLDPE polymerized using a metallocene catalyst]
(Density 0.928, melt index 1.7 g / 10
Minutes)] with a predetermined amount of an antioxidant, a slip agent, and an antiblocking agent, and subjected to T-die extrusion molding to obtain a roll diameter of 30.
Adhesion and cooling to 0 mm, chill roll with surface temperature of 30 ℃,
A 60 μm thick film having the physical properties shown in Table 1 was obtained as a stretch label stock. A stretch label was prepared by punching this stretch label raw material into a predetermined shape.

Example 2 Evolution SP2 instead of Evolution SP2520
020 [trade name, manufactured by Mitsui Petrochemical Industry, LLDPE polymerized using a metallocene-based catalyst (density 0.916,
Melt index 1.5 g / 10 min)], and a thickness of 60 having the physical properties shown in Table 1 in the same manner as in Example 1.
A film of μm was obtained as a stretch label stock. A stretch label was prepared by punching this stretch label raw material into a predetermined shape.

Comparative Example 1 A conventional LLDPE polymer (manufactured by Showa Denko Co., Ltd.) polymerized by using a multi-site type catalyst in place of Evolution SP2520
A stretch label original fabric was obtained in the same manner as in Example 1 except that A-620F, density 0.917, melt index 2.0 g / 10 min) was used. Table 1 shows the physical properties of this product.
Shown in

Comparative Example 2 A stretch label raw fabric was obtained in the same manner as in Example 1 except that the inflation molding machine was used and the cooling was changed to slow cooling by air cooling. The physical properties of this product are shown in Table 1.

Comparative Example 3 Instead of Evolution SP2520, ethylene-vinyl acetate copolymer (vinyl acetate content = 5% by weight) (manufactured by Nippon Unicar Co., Ltd., NUC-3550, density 0.928, melt index 0.5 g / 10 minutes). Example 1 except that
A stretch label stock was obtained in the same manner as. The physical properties of this product are shown in Table 1.

Comparative Example 4 A stretch label raw fabric was obtained in the same manner as in Comparative Example 3 except that the inflation molding machine was used and the cooling was changed to slow cooling by air cooling. The physical properties of this product are shown in Table 1.

[0027]

[Table 1]

Each symbol in Table 1 has the following meaning. SP2520: Evolution SP2520 SP2020: Evolution SP2020 EVA: Ethylene-vinyl acetate copolymer

From the above, in Comparative Example 1 in which the resin material is a commonly used LLDPE, the residual strain rate at the time of 20% elongation is large, there is a problem of partial rubbing, and there is a problem in strength, and the resin material is EVA. In Comparative Example 3, there is a great problem in strength such as considerable rubbing and breakage and a low Young's modulus. Furthermore, in the case of slow cooling without rapid cooling, the haze value becomes excessive regardless of the type of resin material and the transparency is impaired. In contrast,
It can be seen that all of the examples of the present invention are excellent in all characteristics.

[0030]

INDUSTRIAL APPLICABILITY The stretch label of the present invention is versatile, has excellent flexibility and stretchability, has sufficient heat resistance and strength, and has excellent transparency. .

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C08F 210/14 MJH 7446-4J C08F 210/14 MJH

Claims (5)

[Claims] 1. A density of 0.910 to 0.930 g / cm ³ and a melt index of 1.0 to 4.0 g / which are obtained by copolymerizing ethylene and an olefin having 6 or more carbon atoms using a single site catalyst. A stretch label mainly composed of a transparent film having a haze value of 7% or less, which is prepared by forming a linear low-density polyethylene having 10 minutes or a layered product of the polyethylene and an olefin resin and then rapidly cooling it. 2. The stretch label according to claim 1, wherein the single-site catalyst is a metallocene catalyst. 3. The stretch label according to claim 1, wherein the olefin having 6 or more carbon atoms is 1-hexene, 1-octene, 4-methyl-1-pentene, 1-decene. 4. An olefin resin is at least one of an ethylene-vinyl acetate copolymer, a high-pressure process low-density polyethylene, and a linear low-density polyethylene polymerized using a multisite type catalyst, or among these. 3. A blend comprising at least one of these and linear low density polyethylene copolymerized using a single site catalyst, or a resin containing at least one of these as a main component.
Or the stretch label described in 3. 5. A corona discharge treatment is applied to at least one surface of the treated surface, and the wettability index of the treated surface after 2 weeks is 37 dyn.
The stretch label according to any one of claims 1 to 4, wherein the stretch label is applied so as to have a density of not less than / cm.