JP2001134189A - Returnable tack label - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a returnable tack label which is easily stripped by hot water, etc., when a container such as a PET bottle is recycled while keeping the adhesive force of the label. SOLUTION: In this returnable tack label, an adhesive layer is formed on the polyester film side of the substrate which comprises a biaxial oriented polypropylene film and a void containing biaxial oriented polyester film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a returnable tack label which can be easily peeled off with hot water when recycling a container such as a PET bottle.

[0002]

2. Description of the Related Art Usually, a label for displaying the contents is attached to a packaging container, and the label is peeled from the container not only during the distribution process but also until the contents are completely consumed. It is necessary to be attached so that it does not. On the other hand, with the full implementation of the Containers and Packaging Recycling Law, PE
Not only T-bottles but also plastic containers and packaging are applicable. However, in order to recycle these container parts, it is necessary to peel off the adhesive label from the packaging container, so the label can be easily peeled off and the adhesive layer Do not remain in the container,
In addition, the performance that the peeled label floats on water is required.

In order to satisfy these conflicting requirements, various studies have been made on pressure-sensitive adhesives for labels and methods of applying pressure-sensitive adhesives (for example, Japanese Utility Model Publication No. 7-31261 and Japanese Patent Application Laid-Open No. Hei 8-30201). Such).

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a returnable tack label in which these contradictory properties are further improved.

[0005]

Accordingly, as a result of examining the base material of the returnable tack label and its structure, a biaxially oriented polyester film having a biaxially stretched polypropylene film and a biaxially oriented polyester film having a cavity has been obtained. By providing an adhesive layer on the side, it can be seen that the label can be more easily peeled off while maintaining the label adhesive strength,
The present invention has been completed.

That is, the present invention relates to a returnable tack label comprising a base material comprising a biaxially oriented polypropylene film and a void-containing biaxially oriented polyester film, and an adhesive layer provided on the polyethylene terephthalate film side of the base material. ), And a returnable tack label according to claim 1 having a masking layer on a part of the pressure-sensitive adhesive layer. (Claim 2) The returnable tack label according to claim 1 or 2, wherein the void-containing biaxially stretched polyester film has a specific gravity of less than 1. (Claim 3).

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION A returnable tack label of the present invention comprises a substrate comprising a biaxially oriented polypropylene film and a void-containing biaxially oriented polyester film, and an adhesive provided on the cavity-containing biaxially oriented polyester film side of the substrate. It is a returnable tack label consisting of layers.

The biaxially stretched polypropylene film used in the present invention is obtained by stretching a polypropylene film in both the vertical and horizontal directions, and any of a flat film method and a tubular method can be used.

The stretching ratio of the biaxially stretched polypropylene film is preferably 3 to 12 times in both the longitudinal and transverse directions. If it is less than 3 times, the shrinkage is low, so that it does not tend to contribute to the deformation of the label when soaked in hot water. Tends to occur. The aspect ratio of the stretching ratio is 0.3 to
It is preferably 2.5. If you exceed this range,
If the vertical and horizontal balance is lost and the force is not evenly applied to the second layer, and if it is stretched in one direction, the label shrinks even with a little heat after laminating, and the label tends to wrinkle.

[0010] The thickness of the biaxially oriented polypropylene film is preferably from 10 to 70 µm. If it is less than 10 μm, the shrinkage strength is weak, and if it exceeds 70 μm, there is a tendency that the label is lifted by warping.

The biaxially stretched polyester film containing voids used in the present invention is a normal pressure foaming method in which a polyester resin containing a foaming agent is extruded onto a sheet and then foamed in a heating furnace. It can be manufactured by a method such as an extrusion foaming method in which an evaporating foaming agent is injected in the middle of a cylinder, and extruded into the atmosphere from the die tip and foamed.

[0012] By using the biaxially stretched polyester film containing cavities, it is possible to obtain a light weight label which is excellent in cushioning property and small in density. Further, since the pressure-sensitive adhesive described later is held on the unevenness of the surface of the foamed film, the pressure-sensitive adhesive is less likely to remain in the container.

For such a biaxially stretched polyester film containing voids, for example, by using recycled polyester resin or nonstandard resin, it is possible to effectively use petroleum resources.

The polyester resin used in the cavity-containing biaxially stretched polyester film is not particularly limited.
For example, polyethylene terephthalate, polybutylene terephthalate, polycyclohexylene terephthalate and the like can be mentioned. Of these, polyethylene terephthalate is preferred because of its low cost and general availability.

The expansion ratio of the void-containing biaxially stretched polyester film is preferably from 1.45 to 1.80. If it is less than 1.45, there is a problem that the label peeled off by hot water or the like sinks in water. is there.

The specific gravity of the cavity-containing biaxially oriented polyester film is preferably less than 1, more preferably less than 0.90. If the specific gravity exceeds 1, it sinks in water.

The thickness of the cavity-containing biaxially oriented polyester film is preferably from 20 to 100 μm. 20
When the thickness is less than μm, printing is difficult, and it is difficult to remove blemishes during label production. When the thickness exceeds 100 μm, the thickness of the label is increased, so that the film becomes stiff, and the label tends to peel off with a warp.

The method of laminating the biaxially oriented polypropylene film and the void-containing biaxially oriented polyester film is not particularly limited, and the lamination can be carried out by a method such as lamination with a strong adhesive or thermocompression bonding.

By using a biaxially oriented polypropylene film joined with a void-containing biaxially oriented polyester film as a base material, for example, when immersed in hot water at 85 ° C., the polypropylene film on the surface is a biaxially oriented film. Therefore, shrinkage occurs at a relatively low temperature, distortion occurs in the void-containing biaxially stretched polyester film, and hot water is easily immersed between the container and the adhesive, and the label is easily peeled. That is, the shrinkage of the biaxially stretched polypropylene film causes peeling from the outer periphery of the label, so that hot water more easily permeates.

The pressure-sensitive adhesive layer used in the present invention is a layer having a function of adhering a returnable tack label to a container such as a PET bottle, and is not particularly limited, but is peeled off with hot water or a low-concentration aqueous sodium hydroxide solution. It is preferable to form with what is easy to do. Examples of such an adhesive include an adhesive made of an emulsion such as an acrylic resin or an aqueous resin, and a soluble heat-sensitive adhesive that softens when heated. More specifically,
Acrylic resin-based pressure-sensitive adhesives such as solvent-type and emulsion-type adhesives having high hydrophilicity can be used.

In the case of the returnable tack label of the present invention, when a PET bottle is used as a container, the hollow biaxially stretched polyester of the label and the PET bottle adhere to each other. Terephthalate adhesives can be used.

The method of applying the pressure-sensitive adhesive is not particularly limited.
The method can be performed by a method such as a roll coater method, a comma coater method, or a die coater method.

The thickness of the pressure-sensitive adhesive layer is preferably from 10 to 30 μm. When it is less than 10 μm, the adhesive strength to the adherend is insufficient, and when it exceeds 30 μm, the label tends to be hardly peeled off even when immersed in hot water.

It is preferable that a masking agent layer is further provided on the pressure-sensitive adhesive layer. The method for forming the masking agent layer is not particularly limited, but a method described in Japanese Utility Model Laid-Open No. 1-127070 can be used. For example, the exposed state of the pressure-sensitive adhesive layer formed on the entire back surface of the base material composed of the biaxially stretched polypropylene film and the void-containing biaxially stretched polyester film causes the non-adhesive masking over the entire back surface or at a predetermined portion of the back surface. It is preferable that the agent be used to form an infinite number of fine and uniform halftone dots, and that the adhesiveness of the entire label is uniformly reduced. By doing so, the minimum required adhesive force is exhibited, while at the time of peeling, troubles such as tearing are prevented. Further, since the peeling gap is secured, the label can be caused by inserting a nail or a sharp object into the gap, and the label peeling operation can be performed more easily. further,
Since the masking agent is applied on the pressure-sensitive adhesive layer by a printing technique, it is very easy to secure a gap for peeling.

As the masking agent, those which are non-adhesive and can be stably applied on the adhesive layer are preferable.
Examples include varnishes, paints, printing inks, starch, or acrylic or other synthetic resins. For applying the masking agent, a printing technique, in particular, a printing technique using a screen is used. Therefore, when such a printing technique is used, it is possible to adjust the coating amount of the masking agent, in other words, to adjust the adhesive force of the adhesive layer by appropriately selecting the number of lines of the screen.

In masking, the exposed area of the pressure-sensitive adhesive layer is preferably set to 20 to 70%. If it is less than 20%, the label may be peeled off after being attached to the container, or a float may be generated when the label is applied. If it exceeds 70%, a considerable force is required to peel off the label from the container, and hot water Or when immersed in a low concentration sodium hydroxide solution, there is a tendency not to peel off.

The thickness of the masking layer is preferably 2 to 10 μm. When the thickness is less than 2 μm, the masking effect is lost, and when the thickness exceeds 10 μm, the label tends to become uneven when affixed to a container, which tends to cause lifting and wrinkling.

The method for producing a returnable tack label is as follows.
Using a rotary printing machine, peel off the release paper from the cavity-containing biaxially stretched polyester film provided with the pressure-sensitive adhesive layer, form a masking layer on the pressure-sensitive adhesive layer by a printing method, and then unite with the release paper. Printing characters, pictures, photographs, etc. on the surface of the biaxially oriented polyester film containing cavities. afterwards,
After laminating the biaxially oriented polypropylene film with a laminating machine, performing punching and slitting, the returnable tack label is wound up.

The printing press to be used can be used without particular limitation as long as it is a rotary printing press such as a letterpress rotary printing press, an offset rotary printing press, a screen rotary printing press, a gravure rotary printing press, or the like.

[0030]

EXAMPLE Using the following label material and masking agent,
A returnable tack label was prepared.

(1) Label material Super Stik (manufactured by Lintec Co., Ltd., label material (adhesive material for printing), base film / adhesive / release paper) Biaxially oriented polypropylene Brand name PP20 / PL thin / Stretching ratio of 7HL PP40 / PL Thin / 7HL PP60 / PL Thin / 7HL PP: Biaxially stretched polyester film containing about 5 times in the longitudinal direction and about 10 times in the transverse direction. / P0093 / 9K PET75 (Happou) / P0093 / 9K Expansion ratio about 1.5 times, specific gravity 0.8 Synthetic paper (Yupo) film Brand name Yupo 80 (UV) / P0093 / 8LK Synthetic paper material Polypropylene resin

(2) Masking Agent UV Ace OP Varnish G (manufactured by Kuboi Ink Co., Ltd.)

Examples 1-4 and Comparative Examples 1-2 Using a letterpress rotary printing machine, a masking agent was formed on the pressure-sensitive adhesive layer of the second layer film provided with the pressure-sensitive adhesive layer, and then the second layer film was formed. Printed on top. The first layer provided with the pressure-sensitive adhesive layer was stuck together using a laminator, punched and slitted to the final dimensions, and a returnable tack label was obtained. The masking layer was formed so that the exposed area of the adhesive layer was 50%.

The obtained returnable tack label is PE
Affixed to a T bottle and stirred in hot water at 85 ° C, or 8
It was immersed in a stirred 1.5% aqueous sodium hydroxide solution at 5 ° C., and the time until peeling was measured. Also, after peeling,
It was observed whether or not glue residue was present in the bottle, and evaluated according to the following criteria.

◎: No adhesive residue at all ○: 1 to 5% remaining Δ: 5 to 10% remaining ×: 10% or more remaining The results are shown in Table 1.

In the table, biaxially stretched PP represents a biaxially stretched polypropylene film, expanded PET represents a void-containing biaxially stretched polyester film, and synthetic paper represents synthetic paper (Yupo).

[0037]

[Table 1]

From the results shown in Table 1, it can be seen that, in the labels of Examples 1 to 4, both the hot water at 85 ° C. and the aqueous solution of sodium hydroxide at 85 ° C. peeled off the labels in a short time, leaving no adhesive residue.

[0039]

According to the returnable tack label of the present invention, the label can be more easily peeled off when recycling a container such as a PET bottle while maintaining the label adhesive strength.

Claims (3)

[Claims] 1. A substrate comprising a biaxially oriented polypropylene film and a cavity-containing biaxially oriented polyester film,
And a returnable tack label comprising a pressure-sensitive adhesive layer provided on the cavity-containing biaxially oriented polyester film side of the substrate. 2. The returnable tack label according to claim 1, further comprising a masking layer on a part of the pressure-sensitive adhesive layer. 3. The returnable tack label according to claim 1, wherein the void-containing biaxially stretched polyester film has a specific gravity of less than 1.