JP2018091885A - Heat removable adhesive label - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat removable adhesive label which has an excellent adhesiveness with an attachment target body when is used, can rapidly reduce an adhesive force with the attachment target body without causing practically any damages on the attachment target body by heating, and can automatically separate a base material and an adhesive layer by a machine.SOLUTION: The heat-removable adhesive label includes: a base material made of paper; an information display layer on one surface of the base material; and a heat removable adhesive layer in a direct contact with another surface of the base material, the adhesive layer being attached on an attachment target body, the heat removable adhesive layer containing a thermal expansive filler which expands by heat and is not expanding at present in a pressure-sensitive adhesive layer. The ratio A/B is in the range of 1.0 to 5.0 when the thickness of the base material is A and the thickness of the heat-removable adhesive layer is B.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a heat-peelable pressure-sensitive adhesive label suitably used for a physical distribution label or the like, which can be firmly attached to an adherend at normal temperature and can be easily peeled off from the adherend after the adhesive force is reduced by heating. .

  Conventionally, a pressure-sensitive adhesive label having an information display layer displaying various information such as date, content display, and barcode is used for a transport container such as a plastic container. Such a label is peeled off after use, but in order to reuse these containers, it is necessary to peel off after collection easily. Generally, a label using a releasable adhesive is used. Many are used.

  However, a label using a releasable pressure-sensitive adhesive has low adhesive strength and cannot be said to have sufficient adhesive strength, and there is a concern that the label may be lifted off from the end during use. Further, although there is a characteristic that it is difficult to leave glue, there is a problem that it is difficult to remove automatically by mechanical work because it requires human manual work for peeling. Therefore, in recent years, heat-sensitive peelable labels that have sufficient adhesive strength during use and can be easily peeled off by heating have been studied.

Patent Document 1 does not circulate as a label, but is characterized in that, for example, a foaming agent is blended with a pressure-sensitive adhesive having a high-elasticity polymer as a base polymer. A peelable pressure-sensitive adhesive in which the adhesive force is reduced or disappeared by foaming, and an adhesive member that is easy to peel off from an adherend due to the absence of adhesive force when heated are disclosed.
Patent Document 2 discloses an adhesive containing, on one or both sides of a base material, thermally expandable microspheres having an average particle diameter of 18 μm or more and 90% or more of which has a particle diameter of 10 μm or more via a rubber-like organic elastic layer. A heat-peelable pressure-sensitive adhesive sheet having a layer is disclosed.

Japanese Patent Laid-Open No. 05-043851 JP-A-11-166164

As in Patent Document 1, a heat-peelable adhesive using a heat-expandable filler is often used for temporarily fixing electronic components, and is preferably used in an environment where the temperature can be increased on a hot plate or the like. Although it can be used, it is mostly used for applications such as logistics labels that can be applied to adherends with low heat resistance such as plastic containers and peeled off at high speed by applying heat from the outside without damaging the adherend. No consideration has been given.
In Patent Document 2, by providing an adhesive layer containing thermally expandable microspheres on a base material via a rubber-like organic elastic layer, adhesion to an adherend can be increased, and heat treatment can be applied to the adherend. Although a heat-peelable pressure-sensitive adhesive sheet that can be easily peeled is disclosed, since one layer is added between the base material and the heat-peelable pressure-sensitive adhesive, the heat transfer becomes worse and the time required for heat-peeling is extended. Since materials and processes are added, there is a problem that it cannot be manufactured at low cost.
In applications such as logistics labels, it is necessary to adhere firmly to the adherend during use and be able to be easily peeled off from the adherend by heat treatment. Become.
When the adhesive layer containing the thermally expandable microspheres is reduced in adhesion with the adherend due to heat treatment, the adhesion with the substrate is also reduced at the same time. Problems such as adhesive residue where the adhesive remains are caused. Further, when the base material and the adhesive are peeled off, there is a problem that the time for peeling the label from the adherend becomes long even when the same amount of heat is applied.
When trying to increase the adhesion between the base material and the adhesive layer, a method of directly applying to the base material or a method of performing chemical treatment such as corona treatment on the base material is considered, but an information display layer is provided. In the case of a heat-peelable pressure-sensitive adhesive label, the information display layer has problems such as color fogging or coloration inhibition due to solvent or drying heating. It is conceivable to solve problems such as color inhibition by providing a heat-peelable adhesive layer on a peelable substrate and bonding it to a substrate provided with an information display layer. The tendency to decrease is increased.

  In view of the above-mentioned problems, the present inventors have good adhesion with the adherend during use, and reduce the adhesive force with the adherend at high speed without causing any damage to the adherend due to heating. It is intended to propose a heat-peelable pressure-sensitive adhesive label that can be automatically peeled off by a machine without peeling off the substrate and the pressure-sensitive adhesive layer.

The present invention relates to a paper base material, an information display layer provided on one surface of the base material, and heat peeling for attaching to an adherend provided to be in direct contact with the other surface of the base material. A heat-peelable pressure-sensitive adhesive layer, the heat-peelable pressure-sensitive adhesive layer contains an unexpanded thermally expandable filler that expands by heating in the pressure-sensitive pressure-sensitive adhesive layer, and the thickness A of the substrate The heat-peelable pressure-sensitive adhesive label has a ratio A / B of 1.0 to 5.0 with respect to the thickness B of the heat-peelable pressure-sensitive adhesive layer.
The heat-peelable pressure-sensitive adhesive label of the present invention is such that an unexpanded heat-expandable filler expands due to heating, reduces the adhesion between the heat-peelable pressure-sensitive adhesive layer and the adherend, and causes curling of the substrate. is there.
The present invention is a heat-peelable pressure-sensitive adhesive label that can be formed by providing a peelable substrate on the surface opposite to the surface in contact with the substrate of the heat-peelable pressure-sensitive adhesive layer.

In the present invention, the solid content of the unexpanded thermally expandable filler contained in the heat-peelable pressure-sensitive adhesive layer is preferably 4 to 15% by mass.
In the present invention, the average particle diameter of the unexpanded thermally expandable filler contained in the heat-peelable pressure-sensitive adhesive layer is 5 to 50 μm, and it is preferable that the volume expand from the unexpanded state to 10 to 100 times by heating.
In the present invention, the pressure-sensitive adhesive layer containing no thermally expandable filler may have an adhesive force of 14 N / 25 mm or more, and the heat-peelable adhesive layer containing the thermally expandable filler has an adhesive force before heating of 1 N. More preferably, the adhesive strength after heating to a temperature at which the thermally expandable filler expands is 0.01 N / 25 mm or less.
The present invention is better when the expansion start temperature of the unexpanded thermally expandable filler is 70 ° C. to 100 ° C., and is suitably used when the adherend is a plastic container.
The present invention is also a step of forming an information display layer on one surface of the substrate, and a step of forming a heat-peelable adhesive layer on one surface of the peelable substrate, A heat-peeling mold comprising a step of containing a non-expandable thermally expandable filler that expands by heating in the pressure-sensitive adhesive layer, and a step of bonding the other surface of the substrate to the heat-peelable adhesive layer. It is a manufacturing method of an adhesive label.

  The present invention is a heat-peelable pressure-sensitive adhesive label that is firmly attached to an adherend at normal temperature and can be easily peeled off from the adherend after the adhesive force is reduced by heat treatment, and is suitably used for a physical distribution label or the like. .

  If the present invention is used, it can be used as a normal information display label at room temperature, has good adhesion to the adherend, hardly damages the adherend due to heating after use, and has a high adhesive force. Even if a heat-releasable adhesive layer is provided on a peelable substrate and this is bonded to a substrate provided with an information display layer, the substrate and the adhesive layer are not peeled off from the adherend. Can do. At this time, a peeling operation by a human hand is not necessary, and an automatic line operation is possible.

It is a schematic cross-sectional schematic diagram of the heat-peelable pressure-sensitive adhesive label of the present invention. (A) is a schematic cross-sectional schematic diagram before heating of the heat-peelable pressure-sensitive adhesive label of the present invention, and (b) is a schematic cross-sectional schematic diagram after heating of the heat-peelable pressure-sensitive adhesive label of the present invention. It is a rough section schematic diagram showing an example of a manufacturing process of a heat exfoliation type pressure-sensitive adhesive label of the present invention.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
FIG. 1 is a schematic cross-sectional schematic view of the heat-peelable pressure-sensitive adhesive label of the present invention.
Referring to FIG. 1, heat peelability for sticking to a base material 1, an information display layer 2 provided on one surface of the base material 1, and an adherend provided on the other surface of the base material 1. The pressure-sensitive adhesive layer 3 constitutes a heat-peelable pressure-sensitive adhesive label. The heat-peelable pressure-sensitive adhesive layer 3 is a pressure-sensitive pressure-sensitive adhesive layer 4 containing an unexpanded thermally expandable filler 5 that expands by heating.

FIG. 2 is a schematic cross-sectional schematic diagram showing the state (a) before heating and (b) after heating after the heat-peelable pressure-sensitive adhesive label of the present invention is attached to the adherend 6.
The heat-peelable pressure-sensitive adhesive label of the present invention is attached to the adherend 6 through the heat-peelable pressure-sensitive adhesive layer 3 provided on the other surface of the substrate 1 (FIG. 2a). When the heat-peelable pressure-sensitive adhesive label is peeled off from the adherend 6, the heat-expandable filler 5 expands by a simple heat treatment that applies heat to the entire heat-peelable pressure-sensitive adhesive label. When the adhesive strength with the adherend 6 is reduced and the expansion of the heat-peelable adhesive layer 3 exceeds the rigidity of the base material 1, or the contraction force of the base material 1 causes the heat-peelable adhesive layer 3 and the adherend 6 to When the adhesive strength between the two is exceeded, curling of the substrate 1 occurs, and the heat-peelable pressure-sensitive adhesive label can be easily peeled off from the adherend 6.

  As a heating method for the heat-peelable pressure-sensitive adhesive label of the present invention, a heating method such as warm air, infrared heating, high-frequency heating, or spraying high-temperature water vapor can be used. When peeling a heat-peelable pressure-sensitive adhesive label using a paper substrate, a method using water vapor is normally used, but the heat-peelable pressure-sensitive adhesive label of the present invention is commercially available using a hot air heating method. Even industrial dryers can be sufficiently peeled off.

The material used for the base material of the heat-peelable pressure-sensitive adhesive label of the present invention is preferably a material having a function that can be used as a label. preferable. For example, coated paper such as high-quality paper, coated paper, art paper, cast paper, and paper manufactured using a synthetic resin such as synthetic paper as a main raw material. Moreover, these materials may be used independently and can also be used in combination of 2 or more type.
The thickness of the base material is preferably 30 to 150 μm, and more preferably 50 to 90 μm. If the substrate is too thin, it is not preferable because the strength is insufficient and the substrate is torn, and if it is too thick, conduction of heat at the time of peeling is hindered, the rigidity of the substrate becomes strong, and curling becomes difficult. For example, in the case of a highly rigid material such as a PET substrate of about 100 μm, curling due to the expansion of the adhesive layer hardly occurs, and it takes time until the adhesive strength of the central portion of the label is reduced. When using a paper substrate with low rigidity, it is possible to use a simple heating means such as blowing hot air on the surface of the heat-peelable adhesive label affixed to the surface of the adherend. The thermally expandable filler can be expanded, the adhesion with the adherend can be reduced, and the substrate can be curled at the same time.

The information display layer of the heat-peelable pressure-sensitive adhesive label of the present invention may display various information such as date, content display, barcode, etc., using a print layer printed by a printer, thermal head, laser, thermal transfer, etc. The heat-sensitive recording layer may be used. In the present invention, the information display layer includes not only a state where information is displayed but also a state where information can be displayed.
As the information display layer of the heat-peelable pressure-sensitive adhesive label of the present invention, a heat-sensitive recording layer capable of color printing with a thermal head or a laser is particularly preferably used. Such a heat-sensitive recording layer contains a color former such as a leuco dye and a developer, and may optionally contain various additives such as a binder, an inorganic pigment, and a sensitizer. Further, those represented by those used for pressure-sensitive recording paper, heat-sensitive recording paper and the like may be used. When the information display layer is such a heat-sensitive recording layer, a commercially available heat-sensitive recording paper (base paper) in which a heat-sensitive recording layer is previously formed on an inexpensive paper base material is used as it is as a substrate with a heat-sensitive recording layer. Also good. In this case, the surface of the base material with a heat-sensitive recording layer may be subjected to non-heat-sensitive printing, printing, or coating treatment as necessary.
By using a heat-sensitive recording layer capable of color printing on the information display layer, the heat-sensitive recording layer is colored at the time of heat peeling simultaneously with the heat peeling which is the main purpose of the present invention, making it difficult to read other information such as used barcodes. It is possible to prevent unauthorized use and misuse of used labels. In addition, even if the peeling is insufficient, it is preferable because erroneous recognition will not occur in the next step.

As the heat-peelable pressure-sensitive adhesive layer of the heat-peelable pressure-sensitive adhesive label of the present invention, a pressure-sensitive pressure-sensitive adhesive layer containing an unexpanded thermally expandable filler that expands by heating is suitably used.
The pressure-sensitive adhesive used for the heat-peelable pressure-sensitive adhesive layer may be appropriately selected according to the purpose of use in consideration of the adhesive strength, weather resistance, etc. within the range where the effects of the present invention are exhibited. It is preferable that the cohesive failure does not easily occur at a temperature of 80 ° C. to 130 ° C. at which the thermal expansion filler is sufficiently expanded. For example, an acrylic, urethane, silicon, rubber or the like adhesive can be used. Moreover, a tackifier, a hardening | curing agent, etc. can be used suitably as an additive for the characteristic improvement of an adhesive if needed.
The pressure-sensitive adhesive used for the heat-peelable pressure-sensitive adhesive layer may be either a water-soluble pressure-sensitive adhesive or a solvent-based pressure-sensitive adhesive. In the case of using a heat-sensitive recording layer capable of color printing using a heat-sensitive recording material, a water-soluble pressure-sensitive adhesive is preferably used so as not to cause problems such as fogging of the heat-sensitive color developing layer and color development inhibition. A pressure-sensitive adhesive made of an acrylic emulsion is preferable, and a mixture of a water-based acrylic emulsion pressure-sensitive adhesive and a curing agent can be suitably used from the viewpoint of environment and performance.
The thickness of the heat-peelable pressure-sensitive adhesive layer is preferably 20 to 70 μm, and more preferably 30 to 55 μm. If the thickness of the pressure-sensitive adhesive layer is too thin, sufficient adhesiveness before heating cannot be obtained, and if it is too thick, it takes time for heat peeling, and the pressure-sensitive adhesive force after heating is not sufficiently lowered.
The thickness of the heat-peelable pressure-sensitive adhesive layer should be 1.0 to 5.0 in the ratio A / B to the thickness B of the heat-peelable pressure-sensitive adhesive layer when the thickness A is the base material. . Thereby, at the time of heat peeling, the adhesive force between the heat peelable pressure-sensitive adhesive layer and the adherend is reduced, and at the same time, the heat peelable pressure-sensitive adhesive layer expands, or the shrinkage force of the base material is increased between the heat peelable pressure-sensitive adhesive layer and the adherend. By exceeding the adhesion between the substrates, curling of the substrate occurs, and the heat-peelable pressure-sensitive adhesive label can be easily peeled off from the adherend.

The heat-expandable filler used in the heat-peelable adhesive layer is not particularly limited as long as the volume expands by heating and the contact area between the heat-peelable adhesive layer and the adherend surface can be reduced. Those having lower adhesiveness than the adhesive used for the peelable adhesive layer are preferred, and particularly preferably non-adhesive.
As the thermally expandable filler used for the heat-peelable pressure-sensitive adhesive layer, those that start expansion from 70 to 100 ° C. can be suitably used. By using a heat-expandable filler having a thermal expansion start temperature in this range, the heat-peelable pressure-sensitive adhesive layer can be stably formed without expansion even when drying at the time of forming the pressure-sensitive adhesive layer. In addition, when the adherend is a plastic container, it can be easily handled by adhering to the adherend stably during storage and transportation, and the adherend is less damaged when peeled off from the adherend. Since it can peel in time, it is preferable.
As a preferred thermally expandable filler, thermally expanded microcapsules can be used. For example, a liquid gas such as a liquid low boiling point hydrocarbon is encapsulated in an outer shell of a thermoplastic polymer such as polyvinylidene chloride or an acrylonitrile polymer, and the average particle size is preferably 5 to 50 μm, more preferably Is 10 to 16 μm, and those that expand from the unexpanded state to 10 to 100 times by heating are preferable. For example, as commercially available thermal expansion microcapsules, the product name “Matsumoto Microsphere” manufactured by Matsumoto Yushi Seiyaku Co., Ltd., the product name “Expansel Microsphere” manufactured by Nippon Philite Co., Ltd. can be used. is there.

The heat-peelable pressure-sensitive adhesive label of the present invention is preferably peelable from the adherend while the base material and the heat-peelable pressure-sensitive adhesive layer are integrated. A label having a heat-peelable pressure-sensitive adhesive layer is peeled off from the adherend when the heat-peelable pressure-sensitive adhesive layer is removed by heating, but the adhesive force between the substrate and the heat-peelable pressure-sensitive adhesive layer is weakened at that time. And the heat-peelable adhesive layer may separate. When separated, the stress applied to the substrate is relaxed, curling does not occur sufficiently, and the force for separating from the adherend is reduced, so that the time required for peeling from the adherend is increased, which is not preferable. Further, the adhesive remains on the adherend side, which is not preferable.
The heat-peelable pressure-sensitive adhesive layer of the heat-peelable pressure-sensitive adhesive label of the present invention has a pressure-sensitive pressure-sensitive adhesive layer that does not contain a thermally expandable filler (adhesive: polyethylene, 180 ° peel test, peel rate 300 mm / min, substrate 55 μm). Quality paper, adhesive thickness of 20 μm, conditions not described are preferably 14 N / 25 mm or more, more preferably 17 N / 25 mm or more as JIS Z 0237: 2009 compliant. If the pressure-sensitive adhesive layer before the filler is mixed is too weak, it is not preferable because the adhesiveness to the base material is insufficient and the base material is peeled off at the time of heat peeling.

The heat-peelable pressure-sensitive adhesive label of the present invention requires that the base material and the heat-peelable pressure-sensitive adhesive layer have sufficient adhesion even after heating, and the unexpanded heat-expandable filler contained in the heat-peelable pressure-sensitive adhesive layer The solid content is preferably 4 to 15% by mass. Even when a heat-peelable adhesive layer is provided on a peelable substrate and this is bonded to a substrate provided with an information display layer, it is peeled off from the adherend by heating while maintaining sufficient adhesion to the paper substrate. Is possible.
The heat-peelable pressure-sensitive adhesive label of the present invention has an adhesive force before heating of a heat-peelable pressure-sensitive adhesive layer containing an unexpanded thermally expandable filler (adhesive: polypropylene, 180 ° peel test peel speed 300 mm / min). The substrate 70 μm thermal paper, the adhesive thickness 35 μm, the conditions not described are preferably JIS Z 0237: 2009 compliant) 1 N / 25 mm or more, and the adhesive strength after heating to a temperature at which the thermally expandable filler expands is 0 .01 N / 25 mm or less. If the adhesive strength is within this range, sufficient heat is exerted in the state where the heat-peelable adhesive label is adhered to the adherend, while the heat-expandable filler is thermally expanded by applying a simple heat treatment, and heated. It can be easily achieved that the adhesive force between the peelable adhesive layer and the adherend is sufficiently reduced.
Next, an example of the manufacturing process of the heat-peelable pressure-sensitive adhesive label of the present invention will be described.

FIG. 3 is a schematic cross-sectional schematic diagram showing an example of the production process of the heat-peelable pressure-sensitive adhesive label of the present invention.
Referring to FIG. 3, first, as shown in FIG. 3A, the information display layer 2 is formed on one surface of the substrate 1. The information display layer 2 contains a color former such as a leuco dye and a developer, and optionally contains various additives such as a binder, an inorganic pigment, and a sensitizer on one side of the substrate 1. It may be formed by coating on top, and may be one represented by those generally used for pressure-sensitive recording paper, heat-sensitive recording paper and the like.
Next, as shown in FIG.3 (b), the heat peelable adhesion layer 3 for affixing on an adherend to the peelable base material 7 (separator) different from the base material 1 is formed. The heat-peelable pressure-sensitive adhesive layer 3 may be formed by applying a pressure-sensitive pressure-sensitive adhesive layer 4 containing an unexpanded thermally expandable filler 5 on one surface of the peelable base material 4.
Finally, as shown in FIG. 3C, it was formed on the other surface of the substrate 1 (the surface opposite to the surface on which the information display layer 2 was provided) and one surface of the peelable substrate 7 (separator). The heat-peelable pressure-sensitive adhesive layer 3 can be bonded to obtain the heat-peelable pressure-sensitive adhesive label of the present invention.

The heat-peelable pressure-sensitive adhesive label of the present invention is preferably configured so that the substrate and the heat-peelable pressure-sensitive adhesive layer are in direct contact with each other because heat transfer is improved and the time required for heat-peeling can be shortened. In addition, this configuration is preferable because it does not require additional materials and processes and can be manufactured at low cost.
When using a heat-sensitive recording layer capable of color printing using a heat-sensitive recording material such as a leuco dye for the information display layer, use of a paper base material that allows liquid to easily permeate, such as fogging of the heat-sensitive color developing layer and color development inhibition A problem occurs. According to the production method of the present invention, this problem can be solved by forming the information recording layer and the heat-sensitive peelable adhesive layer separately and then bonding them together.

  The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to these examples.

Example 1
100 parts by weight of an aqueous acrylic emulsion pressure-sensitive adhesive (AT-27) is mixed with 1 part by weight of an epoxy curing agent, and a thermally expandable filler (trade name: Expandel (031) DU-40, expansion start temperature 80 to 95 ° C. on the catalog. , Manufactured by Nippon Philite Co., Ltd.) was prepared.
Commercially available thermal paper (substrate thickness 70 μm) provided with a heat-sensitive recording layer on a paper substrate was prepared as a substrate with a heat-sensitive recording layer, and the thickness after drying the previous heat-peelable pressure-sensitive adhesive on the separator substrate was 30 μm. (Coating with a coater so that the ratio A / B of the thickness A of the substrate and the thickness B of the heat-peelable adhesive layer is about 2.3), and drying using an oven at 80 ° C., A heat-peelable pressure-sensitive adhesive layer was formed by laminating with a substrate with a heat-sensitive recording layer. Thus, a heat-peelable pressure-sensitive adhesive label having a peel start temperature of 90 ± 5 ° C. was obtained.

In addition, the adhesive force of the adhesive layer which does not contain the thermally expansible filler which mixed 1 mass part of epoxy-type hardening | curing agents with 100 mass parts of water-system acrylic emulsion adhesive (AT-27) on the paper base material was 17 N / 25mm. . Moreover, the adhesive force of the adhesion layer containing a thermally expansible filler was 14 N / 25mm.
Here, the expansion start temperature of the present example refers to the temperature of the thermostatic chamber in which the expansion of the thermally expandable filler was confirmed when the thermally expandable filler was put in the screw bottle and left in the thermostatic chamber for 10 minutes.
Moreover, it was confirmed that the heat release type pressure-sensitive adhesive label peels from the hot plate when the heat release type pressure-sensitive adhesive label is attached to the hot plate and heated while raising the temperature of the hot plate. Refers to temperature. In the case of the thermally expandable filler used in Example 1, the expansion start temperature was 80 to 85 ° C.

Next, this heat-peelable pressure-sensitive adhesive label was cut into 3 cm square, and attached to a polypropylene plate (PP plate) as an adherend to produce an evaluation sample.
The heating method used was an industrial dryer Hakuko 882 heating gun 1000W.
For evaluation of the peelability of the prepared evaluation sample, when the evaluation sample was heated using a heating gun, the thermally expandable filler contained in the heat-peelable adhesive layer expanded and peeled from the PP plate while curling the substrate. .

(Example 2)
An evaluation sample was prepared in the same manner as in Example 1 except that the amount of the thermal expansion filler mixed with the water-based acrylic emulsion adhesive was 15 mass percent. The adhesive strength before heating of this heat-peelable pressure-sensitive adhesive label was 14 N / 25 mm.
When the evaluation sample was heated using a heating gun, the thermally expandable filler contained in the heat-peelable pressure-sensitive adhesive layer expanded and peeled from the PP plate while curling the substrate.

(Example 3)
An evaluation sample was prepared in the same manner as in Example 1 except that the amount of the thermal expansion filler mixed with the water-based acrylic emulsion adhesive was 4 mass percent. The adhesive strength before heating of this heat-peelable pressure-sensitive adhesive label was 14 N / 25 mm.
When the evaluation sample was heated using a heating gun, the thermally expandable filler contained in the heat-peelable pressure-sensitive adhesive layer expanded and peeled from the PP plate while curling the substrate slightly.

(Comparative Example 1)
An evaluation sample was prepared in the same manner as in Example 1 except that the base material was changed from a thermal paper base material with a heat-sensitive recording layer to a PET base material (thickness 75 μm).
When the evaluation sample is heated using a heating gun, the thermally expandable filler contained in the heat-peelable adhesive layer expands, but it is peeled from both the substrate and the adherend because of insufficient adhesion to the substrate. As a result, a part of the thermally expanded pressure-sensitive adhesive remained attached to a part of the adherend and the base material, and thus could not be peeled off successfully.

(Comparative Example 2)
The base material is a thermal paper (base material thickness 250 μm (the ratio A / B between the base material thickness A and the heat peelable adhesive layer thickness B is about 8.3). An evaluation sample was prepared in the same manner as in Example 1 except that the sample was changed to)).
When the evaluation sample was heated using a heating gun, the thermally expandable filler contained in the heat-peelable adhesive layer expands, but the base material has high rigidity, so curling is unlikely to occur, and even the adhesive at the center of the sample is peeled off. Before this occurred, the PP plate was denatured by heat and could not be peeled off.

DESCRIPTION OF SYMBOLS 1 Base material 2 Information display layer 3 Heat peelable adhesive layer 4 Pressure sensitive adhesive layer 5 Thermally expansible filler 6 Adhering body 7 Strippable base material (separator)

Claims (8)

Paper peelable substrate, information display layer provided on one surface of the substrate, and heat-peelable adhesive for sticking to an adherend provided to be in direct contact with the other surface of the substrate A heat-peelable pressure-sensitive adhesive label having a layer,
The heat-peelable pressure-sensitive adhesive layer contains an unexpanded thermally expandable filler that expands by heating in the pressure-sensitive pressure-sensitive adhesive layer,
A heat-peelable pressure-sensitive adhesive label, wherein the ratio A / B between the thickness A of the substrate and the thickness B of the heat-peelable pressure-sensitive adhesive layer is 1.0 to 5.0.   The heat-peelable pressure-sensitive adhesive label according to claim 1, wherein a peelable base material is provided on a surface of the heat-peelable pressure-sensitive adhesive layer opposite to the surface in contact with the base material.   The heat peelable pressure-sensitive adhesive label according to claim 1 or 2, wherein a solid content of the unexpanded thermally expandable filler contained in the heat peelable pressure-sensitive adhesive layer is 4 to 15% by mass.   The average particle diameter of the unexpanded thermally expandable filler contained in the heat-peelable pressure-sensitive adhesive layer is 5 to 50 µm, and volume expands from an unexpanded state to 10 to 100 times by heating. The heat-peelable pressure-sensitive adhesive label according to any one of 1 to 3.   The heat-peelable pressure-sensitive adhesive label according to any one of claims 1 to 4, wherein the pressure-sensitive adhesive layer not containing the thermally expandable filler has an adhesive strength of 14 N / 25 mm or more.   The heat-peelable pressure-sensitive adhesive label according to any one of claims 1 to 5, wherein an expansion start temperature of the unexpanded thermally expandable filler is 70 ° C to 100 ° C.   The adhesive strength before heating of the heat-peelable adhesive layer is 1 N / 25 mm or more, and the adhesive strength after heating to a temperature at which the thermally expandable filler expands is 0.01 N / 25 mm or less. The heat-peelable pressure-sensitive adhesive label according to any one of claims 1 to 6. A method for producing a heat-peelable pressure-sensitive adhesive label,
Forming an information display layer on one surface of the substrate;
A step of forming a heat-peelable pressure-sensitive adhesive layer on one surface of the peelable base material, the heat-peelable pressure-sensitive adhesive layer containing an unexpanded thermally expandable filler that expands by heating in the pressure-sensitive pressure-sensitive adhesive layer The said manufacturing method including the process which bonds the other surface of the said base material, and the said heat peelable adhesion layer which is what is a thing.

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