JP2000025112A - Stretchable and shrinkable label - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high practical stretchable and shrinkable label having both the advantages of a shrinkable label and a stretchable label with materials different from conventional one. SOLUTION: A label body 1 is formed by a linear low-density polyethylene film polymerized by means of a single site metallocene catalyst, and the film is constituted by performing the orientation such that the refractive index in the circumferential direction (X) of the label body 1 is in the range of 1.515-1.550.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a label to be attached to an object such as a synthetic resin container, a glass container or a metal container. And a stretch shrink label that shrinks by heat.

[0002]

2. Description of the Related Art
For example, as a label to be attached to an object to be attached such as a container made of polyethylene terephthalate (a so-called PET bottle), a shrink label in which a stretched film of polystyrene, polyethylene terephthalate, polyvinyl chloride, or the like is formed in a tubular shape is known. Such shrink labels are:
It can be attached to an object to be mounted by externally fitting to the object to be mounted and by heat shrinking.

There is also known a stretch label in which a film having elasticity is formed in a cylindrical shape, and is stretched by applying an external force, and is reduced to a substantially original shape when the external force is released. Such a stretch label can be attached to an object by extending it to a large diameter and externally fitting the object, and when the external force is released, the elastic label reduces its diameter.

[0004] The shrink label has an advantage of good mounting finish because it adheres closely to the shape of the object to be mounted irrespective of the shape of the object to be mounted. When the temperature rises, spontaneous shrinkage occurs, so that there is a disadvantage that care must be taken (for example, management such as storage at 25 ° C. or less). In addition, for example, when the shrink label is attached to the carbonated beverage container by heat shrinking, the attached position of the label may be displaced due to delicate deformation of the container after opening.

On the other hand, even if the object to be mounted is slightly deformed after being mounted, the stretch label is reduced in diameter by the elastic force and adheres to the object to be mounted. There is an advantage, but on the other hand,
There is a drawback that the stretch label cannot be attached to the unevenly mounted object due to the limit of self-stretchability, that is, the stretch label can be attached only to the straight body part of the object (for example, the body part of a cylindrical container).

Therefore, a label having both advantages is preferable, and the idea of a stretch shrink label has already been made (Japanese Utility Model Laid-Open No. 7-41568).

Japanese Patent Application Laid-Open No. 9-254338 discloses a heat-shrinkable film and a self-stretchable film having both surface layers made of an ethylene-vinyl acetate copolymer or the like and having a Vicat softening point of 60 ° C. or less. A film having at least a four-layer structure of a layer containing a polyolefin-based elastomer and a layer made of a polypropylene-based resin is disclosed.

However, the above-mentioned conventional stretch shrink film is used for packaging foods and miscellaneous goods, and heat shrinks in two directions vertically and horizontally, and is formed into a tubular shape like a shrink label or a stretch label. It is not intended to be used as a container label.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a stretch shrink label which is made of a material different from that of the prior art, has the advantages of a shrink label and a stretch label, and has a high practical value.

[0010]

Accordingly, the present inventor sometimes abbreviates the linear low-density polyethylene (hereinafter, referred to as "metallocene PE") polymerized using a single-site metallocene catalyst which has recently attracted attention. ). That is, metallocene PE is a polyethylene and is relatively inexpensive because it is included in general-purpose resins, and metallocene PE film has properties such as high transparency and resistance to tearing. High target value.

The use of the metallocene PE film for a label is disclosed in Japanese Patent Application Laid-Open No. 9-297539, but the label in this publication is a stretch label and has no heat shrinkability. Also, it is well known that a stretched film after stretching the film and heat-setting to complete the stretching process generally does not have self-stretching (stretchability).

However, the inventor of the present invention has conducted intensive studies and, after devising the stretching treatment so that the refractive index of the film is in a predetermined range, the metallocene PE film has heat shrinkability, They found that they had self-stretching properties, and took measures to solve the above problems based on the findings.

That is, the means is that the label body 1 is formed from a linear low-density polyethylene film polymerized by using a single-site metallocene catalyst, and the film is formed in the circumferential direction X of the label body 1. The stretch shrink label is constituted by performing a stretching treatment so that the refractive index in the range of 1.515 to 1.550 (claim 1).

As described above, the metallocene PE film forming the label body 1 is stretched so that the refractive index in the circumferential direction X is in the range of 1.515 to 1.550, whereby the elastic force is reduced. A stretch shrink label having the property of thermally shrinking in the circumferential direction X while holding it. Therefore, the label can be attached to the object using the self-stretching property of the label, and the label can be extended and contracted after the label is attached by heat shrinkage.

Here, the refractive index in the circumferential direction X of the label body 1 refers to the refractive index measured in the circumferential direction X when the metallocene PE film is formed in a cylindrical shape. Further, the refractive index in the circumferential direction X is 1.515 to 1.55.
The metallocene PE film stretched to be in the range of 0 can be easily obtained by performing a stretching treatment by appropriately selecting a stretching ratio, a stretching heating temperature, and the like in the stretching treatment step. Examples will be described later.

As described above, the refractive index of the metallocene PE film in the circumferential direction X is preferably in the range of 1.515 to 1.550, and more preferably in the range of 1.520 to 1.540. When the refractive index in the circumferential direction X of the metallocene PE film is smaller than 1.515, the heat shrinkage is poor. On the other hand, when the refractive index is larger than 1.550, the heat shrinkability is excellent but the self-shrinkage is poor. It is.

Further, as the single-site metallocene catalyst of the present invention, those disclosed in JP-A-9-297439 may be used. Briefly describing the single-site metallocene catalyst, the single-site metallocene catalyst has a structure in which a metallocene-based transition metal compound and an organoaluminum compound or a boron compound are bonded, and if necessary, silica gel, zeolite, diatomaceous earth, or the like. It may be used by being supported on an inorganic substance.

The metallocene PE of the present invention preferably has a density of 0.900 to 0.935 g / cm ³ (claim 2). If necessary, various additives such as a lubricant, an antioxidant, an ultraviolet absorber, and an antistatic agent may be added to the raw material.

The metallocene PE film having the above refractive index shrinks when heated at a predetermined temperature or higher.
Among them, metallocene PE film was placed in hot water at 80 ° C for 10 minutes.
The heat shrinkage in the circumferential direction X after immersion for 2 seconds (hereinafter, the heat shrinkage in the circumferential direction X may be referred to as “heat shrinkage A”)
Stretching to 10% or more is preferable in that it can be shrunk at a low temperature and a low calorific value (claim 3), and such a label is suitable for being attached to a container having a curved surface, for example.

Here, the heat shrinkage ratio A of the metallocene PE film is defined as 8% of the stretched metallocene PE film.
After immersion in hot water of 0 ° C. for 10 seconds, the shrinkage rate in the circumferential direction X of the label body 1 (the direction that becomes the circumferential direction X when the metallocene PE film is formed into a cylindrical shape) is referred to as the heat shrinkage rate A.
= ｛(Length of original circumferential direction X-length of circumferential direction X after immersion)
/ (Original length in the circumferential direction X)｝ × 100. still,
The heat shrinkage rate A is 10 because the heat shrinkage occurs and the heat shrinkage is attached to the object
%, It is not particularly limited, but for example, it is considered that the heat shrinkage rate is preferably about 10 to 35%, more preferably about 10 to 30%, and still more preferably about 15 to 30%.

Further, metallocene P having the above-mentioned refractive index is used.
The E film has a self-stretching property in the circumferential direction X. Among them, a restoring rate after holding for 3 seconds in a state of being stretched 1.25 times in the circumferential direction X (hereinafter, may be referred to as “restoring rate A”). ) Is 5.0% or less, and the film after immersion in hot water at 80 ° C. for 10 seconds is stretched 1.25 times in the circumferential direction X, and is then restored for 3 seconds (hereinafter, “restoration ratio”). B) may be stretched so as to be 7.0% or less, even after the heat shrinkage treatment (after attachment to the object), This is preferable in that the displacement of the label mounting position is extremely unlikely to occur (claim 4).

Here, the restoration rate A means that the stretched film is stretched 1.25 times the original length in the direction of the circumferential direction X when the metallocene PE film is formed into a cylindrical shape. The rate of restoration by releasing the tensile force after holding for 3 seconds in the state, and the restoration rate A = ｛(length of circumferential direction X after tension release−length of original circumferential direction X) / (element Of the circumferential direction X)｝ × 100. Further, the recovery ratio B is such that after the stretched metallocene PE film is immersed in warm water at 80 ° C. for 10 seconds, the metallocene PE film is immersed in a circumferential direction X when the film is formed into a cylindrical shape. After holding for 3 seconds in a state of being stretched to 1.25 times the length of the rear (after contraction), the ratio of restoring by releasing the tensile force is referred to as a restoring rate B = ｛(peripheral direction after releasing the tension) X length−length of circumferential direction X after immersion) / (length of circumferential direction X after immersion)｝ × 100.

As a range having a preferable self-stretching property, the restoration ratio A is considered to be 5% or less as described above, and a more preferable range is considered to be about 3% or less (in view of the properties of the metallocene PE film, The restoration rate does not fall below 0).

[0024]

Embodiments of the present invention will be described below. As shown by a two-dot chain line in FIG. 1, reference numeral 1 denotes a label body in which a linear low-density polyethylene film polymerized using a single-site metallocene catalyst is formed in a cylindrical shape.

The metallocene PE film is stretched in the width direction (ie, in the circumferential direction X of the label body 1 when formed into a cylindrical shape), and, if necessary, in the longitudinal direction (ie,
The label body 1 is stretched in the longitudinal direction Y) when formed into a cylindrical shape, and the refractive index of the label body 1 in the circumferential direction X is set to 1.
515 to 1.550, more preferably 1.520 to
1.540. The film thickness is
The thickness is not particularly limited, and is formed to a normal thickness (for example, 50 μm).

Further, one surface of the label main body 1 (the mounting object 2)
The surface in contact with is printed with an arbitrary design as a printing layer using a printing ink such as gravure printing using a polyurethane-based ink or the like. On the other hand, a protective film made of, for example, an acrylic resin is formed as an overcoat layer on the other surface of the label body 1 (the surface not in contact with the mounted object 2).

<Manufacturing Method> Next, an example of a method for manufacturing a stretch shrink label having the above-described structure will be described. A linear low-density polyethylene polymerized using a single-site metallocene catalyst is supplied to an extruder, and is fed into an extruder.
Melt extrusion at a temperature of 10 ° C.

This is introduced into a T-type die to form a single-layer sheet. Next, this sheet is heated to about 85 ° C. and stretched four times in the width direction.

Thereafter, the film is fixed in a heat treatment zone at about 85 ° C. under tension, cooled out of the tenter, and wound around a core to produce a metallocene PE film.

Next, a printing layer is formed on one surface of the film by gravure printing using a water-based ink in a design consisting of eight colors, while the other surface of the film is coated with an acrylic resin to prevent damage. A resin is applied to form an overcoat layer, which is taken up as a printing roll.

This printing roll is slit into an appropriate width to form a roll of one row, and the roll is formed into a cylindrical shape such that the printing surface is on the inside and the width direction of the film is the circumferential direction X of the mounting object 2. The stretch shrink label is manufactured by forming a long cylindrical shape by bonding both ends to each other with an adhesive or heat fusion and cutting the long cylindrical body at a predetermined interval.

<Method of Use> The tubular stretch shrink label manufactured in this manner is supplied to an automatic stretch label mounting apparatus, and the label is expanded to have a large diameter by an expanding arm of the apparatus. Mounted object
2. A 1.5 liter container (so-called PET container) made of polyethylene terephthalate, which has been filled inside, is fitted to a container whose body is slightly larger than the periphery of the label. By removing the label, the label is reduced in diameter and mounted on the mounted object 2.

Thereafter, by passing through a steam tunnel (temperature in the tunnel of about 80 to 90 ° C.), the heat shrinks to conform to the shape of the shoulder portion 2b of the article 2 and adhere to it. 2 (see FIG. 1). Then, even after being mounted by heat shrinkage, the label according to the present invention has self-stretchability, so that even if the mounted object 2 is slightly deformed, the label itself is reduced in diameter, and the mounting position is almost likely to shift. Absent.

[0034]

EXAMPLE In the above embodiment, a metallocene PE film having the refractive index shown in Examples 1 to 4 and Comparative Examples 1 to 3 was prepared using metallocene PE having the following composition, and the film was formed into a cylindrical shape. Labels were formed by heating, and the heat shrinkage rate, the restoration rate, and the finish of mounting of each label were examined. Each label was formed by the method exemplified in the above <Production method>. However, each label was formed by changing the stretching ratio in the above <Production method> so as to have the following refractive index.

(Composition of metallocene PE) Density 0.915
g / cm ³ metallocene PE (trade name: Yumerit 15)
40F (Ube Industries, Ltd.)) was used.

(Embodiment 1) In Embodiment 1, the label body 1
The circumferential direction X (“the circumferential direction X” refers to the direction that becomes the circumferential direction when the metallocene PE film is formed into a cylindrical shape and the label body 1 is formed, and the “longitudinal direction Y” is the direction in which the metallocene PE film is A metallocene PE film having a refractive index of 1.520 (referred to as a vertical direction when the label main body 1 is formed in the same manner as above). (Example 2) In Example 2, a metallocene PE film in which the refractive index of the label body 1 in the circumferential direction X was 1.530 was used. Example 3 In Example 3, a metallocene PE film in which the refractive index of the label body 1 in the circumferential direction X was 1.540 was used. Example 4 In Example 4, a metallocene PE film in which the refractive index of the label body 1 in the circumferential direction X was 1.550 was used.

Comparative Example 1 In Comparative Example 1, the label body 1
A metallocene PE film having a refractive index of 1.500 measured in the circumferential direction X was used. Comparative Example 2 In Comparative Example 2, a metallocene PE film having a refractive index of 1.510 in the circumferential direction X of the label body 1 was used. Comparative Example 3 In Comparative Example 3, a metallocene PE film in which the refractive index of the label body 1 in the circumferential direction X was 1.560 was used. Example 2)

(Various tests) The heat shrinkage and the restoration rate were measured by the following method for a plurality (three each) of the labels of Examples 1 to 4 and Comparative Examples 1 to 3, and the average value was obtained.
Also, the finish of mounting was confirmed. . Heat shrinkage 10 cm x from the labels of Examples 1-4 and Comparative Examples 1-3
A test piece of 10 cm (length in the vertical direction Y × length in the circumferential direction X) was cut out, and the test piece was immersed in hot water of 80 ° C. for 10 seconds. The length of Y in the longitudinal direction was measured, and the thermal shrinkage A in the circumferential direction X and the thermal shrinkage B in the longitudinal direction Y were determined by the following equation. Heat shrinkage A = {(original length in circumferential direction X−length in circumferential direction X after immersion) / (original length in circumferential direction X)} × 100 Heat shrinkage rate B = {(original length) Length of direction Y-length of vertical direction Y after immersion) / (original length of vertical Y)｝ × 100. Restoration rate 1 cm x 1 from the labels of Examples 1-4 and Comparative Examples 1-3
A test piece of 0 cm (length in the vertical direction X × length in the circumferential direction X) is cut out, and both ends of the test piece are labeled 1 at room temperature.
After holding for 3 seconds in a state of being stretched 1.25 times the length in the circumferential direction X, the tensile force is released and the length is measured, and the restoration rate A in the circumferential direction X is calculated by the following equation. I asked. Restoration rate A = {(length after release of tension−length of original circumferential direction X) / (length of original circumferential direction X)} × 100 Further, in Examples 1 to 4 and Comparative Examples 1 to 3, 1c from label
A test piece of mx 10 cm (length in the vertical direction Y x length in the circumferential direction X) was cut out, and the test piece was immersed in warm water at 80 ° C for 10 seconds, and then the length in the circumferential direction X after the immersion Was measured.
Next, both ends of the test piece after immersion at room temperature were
After holding for 3 seconds in a state of being stretched 1.25 times the length in the circumferential direction X, the length in the circumferential direction X of the test piece after releasing the tensile force was measured, and the circumferential length was determined by the following formula. The restoration rate B in the direction X was determined. Restoration rate B = {(length after release of tension−length of circumferential direction X after immersion) / (length of circumferential direction X after immersion)} × 100. Finishing of Mounting After the labels of Examples 1 to 4 and Comparative Examples 1 to 3 are mounted (heat-shrinked) on the object to be mounted in the same manner as the above <Usage method>, whether or not there are wrinkles, and the adhesion to the object to be mounted. The appearance of the label mainly after mounting was visually confirmed.

(Test and Evaluation) The test results of the labels of Examples 1 to 4 and Comparative Examples 1 to 3 are shown in Table 1. In the table, in the section of the finished finish, the label showing an extremely beautiful appearance is denoted by ◎, the label showing the beautiful appearance is denoted as a label that can be used as a product, and the label having no commercial value Is represented as x.

[0040]

[Table 1]

The labels in Examples 1 to 4 shrink by heating at 80 ° C. to the extent that shrinks can be attached.
It has good mounting finish, has self-stretchability to the extent that it can be stretched, and has the same properties even after heat shrinkage.

[0042]

As described above, the stretch shrink label according to the present invention has both the advantages of the shrink label and the stretch label, and has a simpler film structure than the conventional stretch shrink label. Can be manufactured. Metallocene PE is used as a raw material for the film.
Is used, it is relatively inexpensive, and has properties such as high transparency, high scratch resistance and high rigidity of the metallocene PE film. Therefore, it is a practically valuable stretch shrink label.

Further, according to the means of claim 3, 8
10% in the circumferential direction of the label body by heating to 0 ° C
As described above, since the heat shrinks, there is a further advantage that the heat shrinks at a low temperature and a low calorific value.

According to the fourth aspect of the present invention, the label has a circumferential recovery rate of 5.0% or less and a temperature of 80 ° C.
Since the restoration ratio in the circumferential direction after heat shrinkage is 7.0% or less, even after the heat shrinkage treatment (after attachment to the object), the elastic shrinkage force due to the extension causes the label attachment position to change. There is a further advantage that deviation is extremely unlikely to occur.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a state in which a stretch shrink label according to the present invention is placed on an object. Note that a perspective view of the label is also shown by a two-dot chain line.

[Explanation of symbols]

 1 ... label body, X ... circumferential direction of label body

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme Court ゛ (Reference) C08L 23:00 (72) Inventor ▲ Yoshi ▼ Shunya 5-3-1-18 Imazukita, Tsurumi-ku, Osaka Inside Fuji Seal Co., Ltd. (72) Inventor Toshio Yamamoto 5-3-18, Imazukita, Tsurumi-ku, Osaka Co., Ltd. Inside the Fuji Seal Co., Ltd. (72) Hideaki Umeda 5-3-18, Imazukita, Tsurumi-ku, Osaka Co., Ltd. F term (reference) 4F071 AA18 AA82 AC18 AE06 AF31Y AF61Y AH06 BA01 BB06 BB07 BC01 BC10 BC11 4F210 AA08C AE01 AG01 AR20 RG04 RG43 RG67

Claims (4)

[Claims] The label body (1) is formed from a linear low-density polyethylene film polymerized using a single-site metallocene catalyst, and the film is formed in a circumferential direction (X) of the label body (1). 1.515-1.
A stretch shrink label, wherein the stretch shrink label is stretched so as to fall within a range of 550. 2. The film according to claim 1, wherein said film has a density of 0.900 to 0.9.
The stretch shrink label according to claim 1, wherein the stretch shrink label is formed of 935 g / cm ³ linear low density polyethylene. 3. The stretch shrink according to claim 1, wherein the linear low-density polyethylene film has a heat shrinkage in the circumferential direction (X) of 10% or more after immersion in hot water at 80 ° C. for 10 seconds. label. 4. The restoration rate after holding the linear low-density polyethylene film for 1.25 times in the circumferential direction (X) for 3 seconds is 5.0% or less, and 80 ° C. hot water After the film was immersed for 10 seconds in the circumferential direction (X) and stretched 1.25 times in the circumferential direction, the restoration rate after holding for 3 seconds was 7.0%.
The stretch shrink label according to any one of claims 1 to 3, wherein: