JP3113858B2 - Stretch label - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Containers such as plastic containers such as PET bottles are used for displaying contents, manufacturers, trademarks, and the like.
It is common practice to attach a tubular stretch label having such contents printed on the outer peripheral surface of a container.

More specifically, as shown in FIG. 3, a cylindrical stretch label (1) is expanded in a radial direction using a jig called a stretcher (Y). After the container (Z) such as a PET bottle is inserted into the stretch-shaped stretch label (1), when the stretched state by the stretcher (Y) is released, the stretch label shrinks due to its elastic recovery force and the container (Z) is contracted. ).

Conventionally, as such a stretch label, Japanese Patent Application Laid-Open No. 55-40474 and Japanese Patent Application Laid-Open No.
No. 606, etc., ethylene-
Most frequently, vinyl acetate copolymer resin (EVA) is used. In addition, as described in JP-A-63-65147, polyethylene is often used.

[0005]

With the recent increase in social demands for environmental protection on a global level, the promotion of recycling of such plastic containers has been demanded from the viewpoint of waste reduction. Especially P
As the environment for recycling ET bottles is being improved, the thickness of stretch labels attached to plastic containers such as PET bottles should be reduced as much as possible from the viewpoint of waste reduction. It has been demanded. Apart from this, it is desirable to make the label thickness as thin as possible from the viewpoint of cost reduction.

However, when a thin film type stretch label is manufactured using an ethylene-vinyl acetate copolymer resin or polyethylene which has been widely used in order to meet such a demand, the following problem occurs. there were.

That is, when the stretch label is attached to the outer periphery of the container by the above-described method, it is often impossible to set the stretch label stably on the stretcher because there is not enough waist as the stretch label. As a result, there has been a problem that mounting failure to the container frequently occurs.

[0008] Usually, after the contents, such as beverages, are filled in a container to which a stretch label is attached, a heat sterilization treatment (usually, a sterilization treatment, for example, by applying a hot water shower at about 60 to 90 ° C from the outer surface of the container). Is performed, but wrinkles are likely to occur on the stretch label after this. As described above, when wrinkles are generated, not only the appearance is poor and the commercial value is remarkably reduced, but also adjacent containers are rubbed during transportation and cause breakage at the wrinkled portions.

The present invention has been made in view of such a technical background, and does not cause mounting failure to a container even when the thickness of a label is reduced, and also provides a stretcher after mounting to a container. An object of the present invention is to provide a stretch label which does not cause wrinkles caused by contact marks of the stretch label.

A second object of the present invention is to provide a stretch label which does not wrinkle even if it is subjected to a heat sterilization treatment after being attached to a container.

[0011]

Means for Solving the Problems In order to achieve the above-mentioned object, the present inventors have conducted intensive studies and found that the material constituting the stretch label has a vinyl acetate content, a density and a melt flow rate value within specified ranges. The specified ethylene-vinyl acetate copolymer resin, and a mixture of polyethylene having a density and a melt flow rate value specified in a specific range, and a mixing ratio of both in a specific range, and a label.
Tensile modulus and 25% tensile residual strain within specified ranges
As a result, it has been found that defective mounting to the container can be prevented and wrinkles can be prevented, and the present invention has been completed.

That is, a stretch label according to the present invention is a stretch label made of a cylindrical synthetic resin mounted on the outer peripheral surface of a container, wherein the synthetic resin has a vinyl acetate content of 3 to 7% by weight, 0.920 ~
0.930 g / cm ³ and JIS K 721
0 (test temperature: 190 ° C, test load: 2.16 kgf)
The melt flow rate value specified by 0.5 to 7.0 g
Ethylene-vinyl acetate copolymer resin of 50 min.
70 parts by weight, and the density is 0.93 g / cm ³ or less,
And polyethylene 50 having a melt flow rate value of 0.5 to 7.0 g / 10 min specified by JIS K 7210 (test temperature: 190 ° C., test load: 2.16 kgf)
Ri Do a mixed resin of 30 parts by weight, the tensile elastic label
The rate is 1600-2800 kg / cm ² and 25
% Tensile residual strain is 5% or less .

A mixed resin of an ethylene-vinyl acetate copolymer resin having a vinyl acetate content, a density and a melt flow rate value within a specified range, and a polyethylene having a density and a melt flow rate value within a specific range. Become
And in particular the mixing ratio of the two is defined within a specific range
In addition, the tensile modulus of the label must be
As a result, it is made to have enough waist as a label,
As a result, the label can be supplied to the stretcher in a stable state, so that the occurrence of poor mounting on the container is significantly reduced.
Or, the occurrence of poor mounting is eliminated. Not only does the label consist of the specific resin described above ,
Elastic modulus and 25% tensile set are specified in specific ranges
As a result, it has a sufficient elastic recovery force, thereby preventing contact marks with the stretcher from being left on the stretch label after the container is attached, and thus preventing appearance deterioration due to wrinkles. You.

In the above, the polyethylene is desirably a linear polyethylene, which can improve the label strength.

Further, a printing layer is provided on the innermost peripheral side in contact with the container, and inorganic fine particles having an average particle diameter of 2 to 4 μm are dispersed and contained in the printing layer, so that the inner peripheral side of the printing layer is provided. It is desirable that the average surface roughness Ra specified in JIS B0601 be in the range of 0.2 to 1.5 μm, so that air remaining at the interface between the container and the printing layer at the time of mounting can be heat sterilized. Occasionally, it can be efficiently removed from the outside, so that wrinkling can be effectively prevented even if heat sterilization is performed after the container is mounted. In addition, the adhesion between the container and the label at the time of mounting is made appropriate, and the mounting failure to the container is more reliably prevented.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, it is necessary to use a resin in which a specific ethylene-vinyl acetate copolymer resin and a specific polyethylene are mixed in a specific ratio as a resin material constituting the stretch label (1). is there. Hereinafter, these specific items will be described in detail.

In the present invention, the vinyl acetate content in the ethylene-vinyl acetate copolymer resin is 3 to 7% by weight.
It is necessary to When the content is less than 3% by weight, the elastic recovery force of the stretch label is reduced, and a contact mark remains at a position where the stretch label has been in contact with the stretcher, which causes wrinkles and poor appearance. On the other hand, if it exceeds 7% by weight, the surface will have a sticky feeling, the label will have insufficient stiffness, and the transparency will be further reduced. Among them, the vinyl acetate content is preferably from 4 to 6.5% by weight, and particularly preferably from 5 to 6% by weight.

The density of the ethylene-vinyl acetate copolymer resin must be 0.920 to 0.930 g / cm ³ . If it is less than 0.920 g / cm ³ , the stiffness of the label decreases due to a decrease in the tensile modulus, and the occurrence of poor mounting increases significantly. On the other hand, if it exceeds 0.930 g / cm ³ , the elastic recovery force of the stretch label is reduced, a contact mark remains at a portion where the stretch label has been in contact, and wrinkles are generated, resulting in poor appearance. In particular, the density of the copolymer resin is preferably 0.922 to 0.928 g / cm ³ . Particularly preferably, 0.924 to 0.927 g / cm
³

Further, the ethylene-vinyl acetate copolymer resin has a melt flow rate value (MFR value) of 0.5 to 7.0.
g / 10 minutes. If the melt flow rate value is less than 0.5 g / 10 minutes, the moldability decreases, while if it exceeds 7.0 g / 10 minutes, the stiffness of the label decreases, and the occurrence of poor mounting increases significantly. Among them, the melt flow rate is preferably 0.8 to 2.5 g / 10 min. The above melt flow rate value is defined by JIS K
It is a melt flow rate value specified by 7210, and is a value measured at a test temperature of 190 ° C. and a test load of 2.16 kgf.

In the present invention, the density of polyethylene must be 0.93 g / cm ³ or less. 0.93g
If it exceeds / cm ³ , the elastic recovery force of the stretch label decreases, and a trace of contact remains at the portion that has been in contact with the stretcher, causing wrinkles and poor appearance. Among them, the density of polyethylene is preferably 0.91 to 0.93 g / cm ³ .

The melt flow rate of polyethylene must be in the range of 0.5 to 7.0 g / 10 minutes.
If the melt flow rate value is less than 0.5 g / 10 min, the moldability decreases, while if it exceeds 7.0 g / 10 min,
The stiffness of the label is lowered, and the occurrence of poor mounting is significantly increased.
Among them, the melt flow rate is preferably 0.8 to 2.5 g / 10 min. In addition, the melt flow rate value is a melt flow rate value specified in JIS K 7210 in the same manner as described above, and is a value measured at a test temperature of 190 ° C. and a test load of 2.16 kgf.

Any polyethylene can be used as long as the density is within the above specified range and the melt flow rate value is within the above specified range. Among them, the label strength can be further improved. From the point
Linear polyethylene is preferred.

In the present invention, the mixing ratio of ethylene-vinyl acetate copolymer resin and polyethylene is such that copolymer resin / polyethylene = 50/50 to 70/30 (weight ratio).
Must be within the range. When the mixing ratio of the ethylene-vinyl acetate copolymer resin is smaller than the above range, the elastic recovery force of the stretch label is reduced, and a contact mark remains at a portion which has been in contact with the stretcher, wrinkles are generated, and the appearance is reduced. It becomes bad. On the other hand, when the mixing ratio of the ethylene-vinyl acetate copolymer resin is larger than the above range, the tensile elasticity decreases, the stiffness of the label decreases, and it becomes impossible to prevent the occurrence of defective mounting on the container. Among them, ethylene-vinyl acetate copolymer resin / polyethylene = 55 / 45-65 /
It is preferably in the range of 35 (weight ratio).

The stretch label according to the present invention has the above-described structure.
Tensile elasticity of label after being composed of specific resin
Rate and 25% tensile set are in the following specific ranges
Must be specified. That is , in order to manufacture the stretch label (1) of the present invention, first, the mixed resin as described above is formed into a film (2) by a known method such as an inflation method or a T-die method . The tensile modulus of this film (2) is 1600 to 2800 kg /
cm ² and a 25% tensile residual strain of 5% or less.
Must have been . Tensile modulus of elasticity is 1600kg / c
not have sufficient stiffness of the label is less than m ^2, that of poor mounting is likely to occur. If the tensile modulus of elasticity is more than 2800kg / cm ² elastic recovery force decline. The rest contact mark the location that has been in contact with the stretcher 25% tensile residual strain exceeds 5%, that wrinkles are likely to occur. Above all, the tensile modulus in the longitudinal direction is 1600 to 2500 kg / cm ² and the tensile modulus in the transverse direction is 2000 to 2800 k.
in the range of g / cm ² is preferred. The tensile modulus is a value measured based on JIS K-7113. The 25% tensile residual strain is a width of 10 m.
m, when a sample film having a length of 100 mm is deformed in the length direction at 500 mm / min, when the stress on the film when the strain is 25% and the stress on the hysteresis curve centering on the strain becomes 0 Is a measured value in the circumferential direction of the label (the direction indicated by (m) in FIG. 1).

In order to produce the stretch label (1) of the present invention, as described above , the above-mentioned mixed resin is first formed into a film (2) by a known method such as an inflation method or a T-die method. Molding. Above all, it is preferable to form a film by an inflation method from the viewpoint that a material having excellent elastic recovery can be obtained. In addition, the method of forming a film is not particularly limited to the method described above.

Next, as shown in FIG. 1, both ends (2a) and (2b) of the film (2) are adhered in a superposed manner by bonding with an adhesive or the like or heat fusion to form a film. Thus, a desired stretch label (1) is obtained. Usually, adhesion by an adhesive is employed, but the adhesive is not particularly limited, but a one-part or two-part urethane-based adhesive is preferably used.

In the above, on one side of the film (2), a display printing layer (10) on which characters, numerals, figures, pictures, patterns, etc. are usually printed is formed. Further, a white print layer (11) is preferably laminated on the display print layer (10), so that when a stretch label is attached to a container, when a label is viewed by a person, the display is performed. The white print layer (11) is present on the back side of the print layer (10), and the display of the print layer (10) for display can be visually recognized by a person with higher brightness. The printing layer can be formed by, for example, gravure printing or flexographic printing, but is not particularly limited to these methods, and other known methods may be used. Among them, if they are formed by flexographic printing, there is an advantage that the cost can be reduced because the amount of application is small. In addition, before laminating a printing layer, it is desirable that the laminating surface of the film (2) is subjected to corona discharge treatment in advance to have a surface tension of 36 to 42 dyne / cm.
Thereby, the adhesion between the print layer and the film can be further improved.

In the above, it is desirable that inorganic fine particles are dispersed and contained in the white print layer (11) so that the surface thereof has an appropriate surface roughness. The inorganic fine particles are not particularly limited, but include, for example, silica, titanium oxide and the like, and among them, silica is preferred. As the inorganic fine particles, those having an average particle diameter of 2 to 4 μm are preferable from the viewpoint of ensuring printability. If the thickness exceeds 4 μm, streaks enter the surface and the commercial value is lowered, which is not preferable. Further, the content of the inorganic fine particles is preferably 2 to 5% by weight in the white print layer (11) from the viewpoint of securing an appropriate surface roughness.

Above all, by dispersing and containing the above-mentioned inorganic fine particles, the average surface roughness of the surface of the white printing layer (11) on the side in contact with the container is preferably in the range of 0.2 to 1.5 μm. . If the average surface roughness is less than 0.2 μm, wrinkles are likely to be generated during heat sterilization, which is not preferable. Among them, the average surface roughness is more preferably in the range of 0.5 to 1.0 μm. In addition, the said average surface roughness is average surface roughness (Ra) prescribed | regulated by JISB0601.

As shown in FIG. 2, the film provided with such a printed layer has both ends (2a) and (2b) such that the side provided with the white printed layer (11) is on the inside.
Are adhered in a superposed manner to form a tubular stretch label (1).

The attachment of the stretch label (1) is performed, for example, as follows. That is, as shown in FIG. 3, the tubular stretch label (1) is externally fitted to a stretcher (mounting jig), and then the stretcher (Y).
After expanding the diameter of the stretch label (1), P
After the container (Z) such as an ET bottle is inserted and arranged, the expanded state by the stretcher (Y) is released, and the stretch label (1) is attached to the container (Z).

[0032] At this time, stretch label (1) of the present invention Ri Do the specific resin as mentioned above, and label
By tensile elastic modulus Le are defined in a specific range, because they are made to have sufficient stiffness, when attaching the label to the stretcher (Y), the label (1) stretcher (Y ) Does not bend over, and can be externally fitted to a predetermined position of the stretcher (Y). That is, the label (1) can be supplied to the stretcher (Y) in a stable state. Therefore, the stretch label (1) can be securely attached to a predetermined position of the container (Z).

In addition, the stretch label (1) is made of the above-mentioned specific resin, and the tensile elasticity of the label
Since the modulus and the 25% tensile residual strain are specified in a specific range, it has a sufficient elastic recovery force. Therefore, the stretch label (1) attached to the container (Z) has a trace of contact with the stretcher. The occurrence of wrinkles due to this is prevented.

Further, when the average surface roughness of the surface of the white printing layer (11) in direct contact with the container (Z) on the side in contact with the container is in the range of 0.2 to 1.5 μm, At this time, the air left between the container (Z) and the white print layer (11) can be efficiently released to the outside even during heat sterilization, so that even when heat sterilization is applied, wrinkles are generated. Occurrence can be reliably prevented. Further, since the average surface roughness is in such a specific range, the container (Z)
There is also an advantage that the adhesiveness between the label (1) and the label (1) is at an appropriate level in mounting, and a defective mounting due to too large adhesiveness between the two (Z) and (1) can be reliably prevented.

[0035]

Next, specific embodiments of the present invention will be described.

Example 1 The vinyl acetate content was 5.5% by weight and the density was 0.926 g.
/ Cm ³ , 70 parts by weight of an ethylene-vinyl acetate copolymer resin having a melt flow rate of 1.1 g / 10 minutes, a density of 0.928 g / cm ³ , and a melt flow rate of 1.7 g / 10 minutes. Was mixed with 30 parts by weight of linear polyethylene, which was formed into a film having a thickness of 80 μm by an air-cooled inflation method, and one surface thereof was subjected to a corona discharge treatment. At this time, the tensile modulus of the film in the longitudinal direction and the transverse direction (the circumferential direction when formed into a cylindrical shape), and 25
% Tensile residual strain was measured.

Next, a display printing layer having a required design is formed by flexographic printing using a coloring ink on the corona discharge treated surface of the film, and then a flexographic printing is performed using a white ink containing no inorganic fine particles. Printing was performed to form a white print layer.

On the other hand, after performing a corona discharge treatment on the longitudinal end of the film on the non-printing surface, the ends are overlapped and adhered using a urethane-based adhesive, so that the print layer is formed on the inner peripheral surface. Tubular stretch label (outer peripheral length 274)
mm, vertical length 115 mm).

<Examples 2 to 7> An ethylene-vinyl acetate copolymer resin having the properties shown in Table 1 and a polyethylene having the properties shown in Table 1 were prepared.
The same procedure as in Example 1 was carried out except that the white mixed layer was formed by flexographic printing using a white ink containing 4% by weight of silica having an average particle diameter of 3 μm, using a resin mixed at the ratio shown in Table 1. -Like stretch label was obtained. The thickness of Example 3 was set to 60 μm.

[0040]

[Table 1]

Comparative Examples 1 to 7 An ethylene-vinyl acetate copolymer resin having the properties shown in Table 2 and a polyethylene having the properties shown in Table 2 were prepared.
In the same manner as in Example 1 except that the resin mixed at the ratio shown in Table 1 was used, a tubular stretch label was obtained.

Reference Example 1 A stretch label having a thickness of 100 μm was produced in the same manner as in Example 1 using only the ethylene-vinyl acetate copolymer resin which has been frequently used in the past.

[0043]

[Table 2]

Each stretch label produced as described above was evaluated according to the following test method. Table 3 shows the results.

A. Wearability evaluation method As shown in FIG. 3, the stretch label is supplied to the stretcher by an automatic mounting machine, and is set. The stretch label is expanded in the radial direction by the stretcher. After the PET bottle is inserted into the PET bottle, the expanded state is released, the stretch label is attached to the PET bottle, and the attached state at this time is visually observed to determine whether or not the label is properly attached. Examined. The evaluation is performed on 100 samples, and the occurrence rate of the mounting failure (the number of mounting failure occurrences / the number of samples) is checked.
Thereby, the wearability was evaluated. Incidence of mounting failure is 1 /
Those having a value of 100 or less were regarded as acceptable.

B. Presence / absence of contact traces of stretcher The stretch labels attached as described above were examined for contact traces of the stretcher.

C. Wrinkle Prevention After filling a PET bottle with a stretch label as described above with a carbonated beverage, perform low-temperature heat sterilization with a 70 ° C hot water shower for 50 minutes, and then determine whether or not the stretch label is wrinkled. The evaluation was based on criteria. (Criterion criteria) No wrinkles occurred ... "○" Wrinkles slightly occurred ... "△" Many wrinkles occurred ... "x"

[0048]

[Table 3]

As is clear from Table 1, the stretch labels of Examples 1 to 7 of the present invention did not have any improper mounting at the time of mounting to the container, or the occurrence of the improper mounting was significantly suppressed. . There was no trace of contact by the stretcher. Furthermore, in Examples 2 to 7, no wrinkles were generated on the label even if the heat sterilization treatment was performed after the label was attached to the container.

On the other hand, in Comparative Examples 1 to 7, which deviate from the scope of the present invention, the defective mounting rate at the time of mounting on the container was high, and the generation of wrinkles on the label could not be prevented.

[0051]

As described above, the stretch label of the present invention comprises an ethylene-vinyl acetate copolymer resin having a vinyl acetate content, a density and a melt flow rate within specified ranges, a density and a melt flow rate. In addition to the fact that the resin consists of a mixed resin with polyethylene whose value is specified in a specific range, and that the mixing ratio of both is specified in a specific range,
Therefore, if the tensile modulus of the label is specified in a specific range , the label has sufficient waist as a label, and thus the label can be supplied to the mounting jig in a stable state. It is possible to remarkably reduce improper mounting on the device, or eliminate improper mounting. Furthermore, in addition to being composed of the specific resin described above , the tensile modulus of the label and the 25%
Since the tension set is specified in a specific range, it has a sufficient elastic recovery force, and therefore, prevents wrinkles caused by the trace of contact with the stretcher on the stretch label after being attached to the container. Can be.

When the polyethylene is a linear polyethylene, the label strength can be further improved.

Further, a printing layer is provided on the innermost peripheral surface side in contact with the container, and inorganic fine particles having an average particle diameter of 2 to 4 μm are dispersed and contained in the printing layer, whereby the inner peripheral surface side of the printing layer is provided. When the average surface roughness Ra specified in JIS B0601 is in the range of 0.2 to 1.5 μm, air remaining between the container and the printed layer at the time of mounting is subjected to heat sterilization. Can also be efficiently removed to the outside, so that wrinkles can be reliably prevented from occurring even when heat sterilization is performed after attachment to the container. In addition, the adhesion between the container and the label at the time of mounting becomes appropriate, and therefore, the occurrence of defective mounting can be more reliably prevented.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a stretch label according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA in FIG.

3A and 3B are perspective views showing an example of a procedure for attaching a stretch label to a container, wherein FIG. 3A shows a state in which the label is supplied to a stretcher, FIG. (C) shows a state in which the container is inserted into the label, and (d) shows a state in which the expanded state by the stretcher is released and the container is attached to the container.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Stretch label 2 ... Film 10 ... Display printing layer 11 ... White printing layer Y ... Stretcher Z ... Container

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G09F 3/04 B32B 27/28

Claims (3)

(57) [Claims] 1. A stretch label made of a cylindrical synthetic resin mounted on an outer peripheral surface of a container, wherein the synthetic resin has a vinyl acetate content of 3 to 7% by weight and a density of 0.9.
20 to 0.930 g / cm ³ and JIS K
7210 (test temperature: 190 ° C, test load: 2.16k
gf) has a melt flow rate value of 0.5 to
50-70 parts by weight of an ethylene-vinyl acetate copolymer resin having a density of 7.0 g / 10 minutes, a density of 0.93 g / cm ³ or less, and JIS K
7210 (test temperature: 190 ° C., test load: 2.16
kgf) has a melt flow rate value of 0.5 to
Ri Do resin mixture of polyethylene 50-30 parts by weight of 7.0 g / 10 min, tensile modulus of the label 1600~2800kg / cm ²
And a 25% tensile residual strain of 5% or less . 2. The stretch label according to claim 1, wherein the polyethylene is a linear polyethylene. 3. A printing layer is provided on the innermost peripheral surface side in contact with the container, and inorganic fine particles having an average particle diameter of 2 to 4 μm are dispersed and contained in the printing layer. JI
The average surface roughness Ra defined by SB0601 is 0.2
2. The method according to claim 1, wherein the distance is in the range of 1.5 to 1.5 .mu.m.
Or the stretch label according to 2 .