JPH0777939A - Pressure-sensitive type track adhesive label - Google Patents

Abstract

PURPOSE:To provide the pressure sensitive type tacky adhesive label which is produced by using a pressure sensitive type tacky adhesive compsn. consisting of an aq. dispersion, has water resistance to prevent the label from being peeled by dew condensation, etc., when adhered to an adherend and easily peels of itself when immersed into a hot aq. solvent (for example, water, alcohol, aq. caustic soda soln., etc.). CONSTITUTION:The pressure sensitive type tacky adhesive 3 of the pressure sensitive type tacky adhesive label successively provided with a pressure sensitive type tacky adhesive layer 3 and a release sheet on the rear surface of a label base 1 consists of the pressure sensitive type tacky adhesive formed by adding a thermally expanding agent of an expansion initiation temp. of a range from 50 to 120 deg.C at 1 to 20 pts.wt. to 100 pts.wt. pressure sensitive type tacky adhesive compsn. consisting of the aq. dispersion of a resin having a particle size of <=500nm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used by adhering it to an adherend such as a glass bottle, a plastic bottle or the like, or to other adherends. It is an adhesive label that can be collected and reused.
In particular, it relates to a pressure-sensitive adhesive label produced using a pressure-sensitive adhesive composition of an aqueous dispersion.

[0002]

2. Description of the Related Art A conventional pressure-sensitive adhesive label is provided with a pressure-sensitive adhesive layer coated with a pressure-sensitive adhesive composition and a release sheet on the back surface of a label substrate (sheet-shaped substrate). It is what

As components of the pressure-sensitive adhesive composition, a polymeric material and a tackifier are basic components, and in some cases, a plasticizer, a preservative, a dispersant, a defoaming agent, a filler, an antiaging agent, etc. May be added.

Here, the polymer material is a component that gives an adhesive force, and is, for example, an acrylic resin-based resin, a vinyl resin-based resin, an ester resin-based resin, a urethane resin-based resin, and a co-polymer synthesized from monomers thereof. Polymer compounds such as coalesced products and natural rubber and synthetic rubber are used. What is a tackifier?
It is a component for enhancing the tackiness, and for example, a resin such as a rosin derivative, a terpene resin system, a phenol resin system, a xylene resin system is used.

A pressure-sensitive adhesive composition containing the above polymeric material and a tackifier as basic components is applied to at least one side of a substrate,
A pressure-sensitive adhesive sheet is manufactured by providing a pressure-sensitive adhesive layer by drying and stacking a release sheet. Then, the pressure-sensitive adhesive sheet is appropriately punched and cut into label-shaped small pieces to manufacture a pressure-sensitive adhesive label. Further, the pressure-sensitive adhesive label is peeled off from the release sheet and attached to various adherends.

The pressure-sensitive adhesive composition is roughly classified into a solvent type and an aqueous dispersion type, depending on the form of the liquid. Generally, the solvent type can obtain high adhesive properties, but since an organic solvent is used as a solvent, there is a high risk in work and hygiene. The aqueous dispersion type is less dangerous than the solvent type, but is inferior in adhesive property. For these reasons, the physical properties and the like of the aqueous dispersion type have been vigorously improved, but there is no aqueous dispersion type pressure-sensitive adhesive having an adhesive physical property superior to that of the solvent type.

The pressure-sensitive adhesive label is used by being adhered to, for example, a glass plate, a stainless plate, a polyethylene plate, a polyester film, various containers such as glass bottles and plastic bottles, and other adherends such as articles. However, when it is used as a display label for containers for soft drinks, it is required that the pressure-sensitive adhesive label does not peel off due to dew condensation due to cooling, exposure to water, or the like, that is, water resistance. Furthermore, when a pressure-sensitive adhesive composition comprising an aqueous dispersion is used, good dispersibility in water is required so that stable coating can be performed. As described above, the water resistance of the pressure-sensitive adhesive layer and the dispersibility of the pressure-sensitive adhesive composition in water must be compatible.

Further, when the pressure-sensitive adhesive label that has been once attached is to be peeled from the adherend, such as when washing a glass bottle to be reused, it is required that the label can be easily removed.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of these problems, and the problem is that it is produced using a pressure-sensitive adhesive composition comprising an aqueous dispersion. When adhered to an adherend, it has water resistance that does not peel off due to dew condensation, etc., and in an aqueous thermal solvent (for example,
It is intended to provide a pressure-sensitive adhesive label which is easily immersed in water, alcohol, an aqueous solution of caustic soda, etc. to be easily peeled off.

[0010]

In order to solve this problem, the present invention provides a pressure-sensitive adhesive label in which a pressure-sensitive adhesive layer and a release sheet are sequentially provided on the back surface of a label substrate, wherein the pressure-sensitive adhesive is 1 to 20 parts by weight of a thermal expansion agent having an expansion starting temperature in the range of 50 to 120 ° C. is added to 100 parts by weight of a pressure-sensitive adhesive composition composed of an aqueous resin dispersion having a particle diameter of 500 nm or less. And a pressure-sensitive adhesive label.

The present invention will be described in detail below. FIG. 1 shows a cross-sectional structure of an example of the pressure-sensitive adhesive label of the present invention. A base material 1 such as a plastic film or synthetic paper, a pressure sensitive adhesive layer 3 is provided on the back surface thereof, and a release sheet 5 is further laminated. If necessary, a plasticizer, a preservative, a dispersant, a defoaming agent, a filler, an antiaging agent, etc. may be added to the pressure-sensitive adhesive composition.

Further, an anchor coat layer or a vapor deposition layer may be provided on the surface of the base material in order to apply the display layer 2 with a picture, a character, a symbol or the like by printing or the like. The printing of the display layer and the anchor coat layer is preferably performed before coating the pressure-sensitive adhesive composition in consideration of the amount of heat applied by drying or the like, but the thermal expansion agent 4 in the pressure-sensitive adhesive layer is preferably used. Does not expand,
It may be applied after coating the adhesive composition.

The above-mentioned polymer material is an aqueous resin dispersion having a particle diameter of 500 nm or less, and is a resin synthesized from acrylic resin, vinyl resin, ester resin, urethane resin and monomers thereof. Polymers and polymer compounds such as natural rubber and synthetic rubber are used. If the particle size is 500 nm or more, the water resistance is poor.

The above-mentioned thermal expansion agent is one in which a core substance is encapsulated by a polymer of an outer shell substance, and when the temperature is raised, the encapsulated core substance is gasified and the outer shell itself swells like a balloon ball. is there. The shell material is classified into an inorganic type and an organic type, and typical examples thereof include glass, alumina, zirconia, silica, silane, carbon, vinylidene chloride, vinylidene chloride / acrylonitrile copolymer and the like. Examples of the core substance to be encapsulated include hydrocarbons such as isobutane and propane, and a foaming agent such as sodium bicarbonate, azobisisobutyronitrile and ammonium carbonate may be used.

The expansion start temperature of the thermal expansion agent can be adjusted by changing the combination of the shell material and the core material. The expansion start temperature is in the range of 50 to 120 ° C, and particularly preferably in the range of 80 to 100 ° C. Expansion start temperature is 5
If the temperature is lower than 0 ° C., the thermal expansion agent 4 will largely swell during the drying after coating, and the adhesive force will decrease. Also,
If it is higher than 120 ° C., the peeling time of the pressure-sensitive adhesive label will be long in the bottle washing process. The particle diameter of the thermal expansion agent 4 is in the range of 1 to 100 μm, and particularly preferably in the range of 5 to 30 μm.

The addition ratio of the heat expansion agent to the pressure sensitive adhesive composition is 1 to 20 parts by weight, preferably 3 to 10 parts by weight, relative to 100 parts by weight of the pressure sensitive adhesive composition. If the addition amount of the thermal expansion agent is less than 1 part by weight, the label peeling time becomes long in the bottle washing process.
If it is more than the weight part, the adhesive strength will be reduced.

FIG. 2 shows a state in which the pressure-sensitive adhesive label according to the present invention is appropriately attached to the surface of an adherend 6 such as a container or other article by a pressure-sensitive adhesive layer.

[0018]

According to the present invention, 100 parts by weight of an aqueous dispersion type pressure-sensitive basic pressure-sensitive adhesive composition, in which a resin aqueous dispersion having a particle diameter of 500 nm or less is used as a polymer material, is used as a base material and an expansion starting temperature is 50 to A pressure-sensitive adhesive layer containing 1 to 20 parts by weight, preferably 3 to 10 parts by weight, of a thermal expansion agent in the range of 120 ° C., preferably 80 to 100 ° C., and a release sheet laminated thereon, and 500 nm as a polymer material. By using a resin aqueous dispersion having the following particle size, a smoother coated surface is obtained, and since the particle size is small, the dispersibility is good, resulting in high adhesive strength and good water resistance. Become.

Further, by adding the above-mentioned thermal expansion agent, the pressure-sensitive adhesive label can be easily peeled off when it is desired to peel it off. The method for peeling off the pressure-sensitive adhesive label will be described in detail below.

The pressure-sensitive adhesive label, which is adhered to the adherend through the pressure-sensitive adhesive layer, contains the thermal expansion contained in the pressure-sensitive adhesive layer when immersed in an aqueous hot solvent having a temperature of 60 ° C. or higher. The agent expands due to the heat of the hot solvent. As a result, a space is created at the interface between the pressure-sensitive adhesive layer and the adherend such as a container such as a glass bottle or a plastic bottle, or an article such as other articles, and the entry of the aqueous solvent is promoted. Then, the pressure-sensitive adhesive layer is in a state of being easily removed by the invading aqueous solvent,
Extends in the direction of expansion of the thermal expansion agent. As a result, the pressure-sensitive adhesive label is self-peeled in several minutes while curling outward from the adherend.

[0021]

【Example】

<Example 1> 100 parts by weight of a pressure-sensitive basic pressure-sensitive adhesive composition (solid content) using an aqueous dispersion of an acrylic acid ester copolymer having a particle diameter of 300 nm as a polymer material, a thermal expansion agent (particle size 10 to 10). 20 μm, expansion start temperature 80 ° C.), outer shell material: vinylidene chloride-acrylonitrile copolymer,
Core material: Using isobutane, 3 parts by weight were mixed to prepare a pressure-sensitive adhesive composition exhibiting an aqueous resin dispersion.

Thereafter, 50 μm of the above pressure-sensitive adhesive composition was added.
m-thick polyester film is applied to one side of the label base material and dried at 45 ° C for 2 minutes, and a release sheet is overlaid thereon, and a pressure-sensitive adhesive having a thickness of 24 g / m ^{2 is applied to} one side of the label base material. A pressure-sensitive adhesive sheet having an agent layer was prepared.

Example 2 A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that the amount of the thermal expansion agent added in Example 1 was changed from 3 parts by weight to 10 parts by weight.

<Comparative Example 1> The particle size of the acrylic acid ester copolymer in Example 1 was 300 nm to 800 nm.
A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that the thickness was changed to nm.

Comparative Example 2 A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that the amount of the thermal expansion agent added in Example 1 was changed from 3 parts by weight to 0.3 part by weight.

Comparative Example 3 A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that the amount of the thermal expansion agent added in Example 1 was changed from 3 parts by weight to 30 parts by weight.

<Confirmation test> Next, these pressure-sensitive adhesive sheets were appropriately cut into a required size to obtain pressure-sensitive adhesive labels. In order to check the characteristics of these pressure-sensitive pressure-sensitive adhesive labels, a confirmation test was conducted on adhesive strength, water resistance, and bottle washing properties as follows.

<Adhesive strength> The release sheet of the pressure-sensitive adhesive label having a width of 25 mm is peeled off, and the adhesive surface is attached to a glass plate.
The adhesive strength was measured after standing for 4 hours. The laminating method and the adhesive force measuring method conformed to JIS standard Z-0237, and the measured value was 1000 g / 25 mm or more, which was regarded as acceptable.

<Water resistance> The release sheet of the pressure-sensitive adhesive label having a size of 50 mm x 100 mm is peeled off, and the adhesive surface is attached to a glass plate to obtain an adhesive article, which is immersed in water at 25 ° C for 24 hours. Then, the self-peeling property of the label substrate was observed. Note that the self-peeling property means that the label itself is peeled off without an external force. If there was no self-peeling property, it was accepted.

<Bottleability> The release sheet of the pressure-sensitive adhesive label having a size of 50 mm × 100 mm is peeled off, and the adhesive surface is attached to a glass plate to obtain a sticking product, which is placed in a 3% caustic soda aqueous solution at 80 ° C. The label was soaked for up to 20 minutes, and the self-peeling time of the label was measured. The self-peeling time is the time until self-peeling. A self-peeling time within 10 minutes was regarded as acceptable.

<Comprehensive Evaluation> When all of the above three tests passed, the comprehensive evaluation was passed. The results are shown in Table 1.

[0032]

[Table 1]

[0033]

The pressure-sensitive adhesive label of the present invention comprises a pressure-sensitive adhesive layer obtained by applying a pressure-sensitive adhesive composition comprising an aqueous dispersion containing a heat-expanding agent to a label substrate. The pressure-sensitive adhesive label of the present invention, which is an adhesive label and is adhered to an adherend (for example, a glass product, a stainless steel product, a polyester product, etc.), is water resistant to cold water or room temperature water. When it is desired to peel off the pressure-sensitive adhesive label at the time of washing the body etc., it has an effect that it can be easily peeled off by immersing it in an aqueous hot solvent at 60 ° C. or higher (for example, water, alcohol, caustic soda aqueous solution, etc.). .

[0034]

[Brief description of drawings]

FIG. 1 is a schematic side sectional view of a pressure-sensitive adhesive label of the present invention.

FIG. 2 is a schematic side sectional view showing a state in which the pressure-sensitive adhesive label of the present invention is attached to an adherend.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... Display layer 3 ... Pressure-sensitive adhesive layer 4 ... Thermal expansion agent 5 ... Release sheet 6 ... Adherent

Claims (1)

[Claims] 1. A pressure-sensitive adhesive label having a pressure-sensitive adhesive layer and a release sheet provided on a back surface of a label base material in this order, wherein the pressure-sensitive adhesive comprises a resin aqueous dispersion having a particle diameter of 500 nm or less. A pressure-sensitive adhesive label comprising 100 parts by weight of an adhesive composition and 1 to 20 parts by weight of a thermal expansion agent having an expansion starting temperature in the range of 50 to 120 ° C.