JPH09151361A - Thermosensible tacky sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare a thermosensimble tacky sheet having non-tackiness at a normal temperature and exhibiting tackiness by heating and useful as a label, etc., by providing a thermosensible tackifier layer containing a specific component on one surface of a base material. SOLUTION: This thermosensible tacky sheet is obtained by providing a thermosensible tacky agent layer containing (A) a thermoplastic resin, (B) a solid plasticizer and (C) tacky microspheres (preferably having 10-60μm average particle diameter) on one surface of a base material. As the component A, e.g. a styrene-butadiene copolymer or a vinyl acetate-ethylene-styrene copolymer, etc., is exemplified and its glass transition temperature is preferably from -10 deg.C to 60 deg.C. As the component B, a diphenyl phthalate or a sucrose benzoate, etc., is exemplified and its melting point is preferably 5-100 deg.C, more preferably 60-80 deg.C. The component C is obtained by using a (meth)acrylate such as ethyl acrylate as a main component, copolymerizing it with a monomer such as (meth) acrylic acid and making to a spherical body. Preferably, 100 pts.wt. of the component A is mixed with 50-300 pts.wt. of the component B and 10-400 pts.wt. of the component C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive pressure-sensitive adhesive sheet which has a surface which is non-tacky at room temperature but which exhibits tackiness when heated and is used as a label or the like.

[0002]

2. Description of the Related Art Conventionally, labels have been attached to glass bottles such as soft drinks, alcoholic beverages, and chemical bottles by attaching a label provided with a water-soluble adhesive such as casein or starch on the back surface of a base material by an automatic labeler or the like. A method of attaching, or a method of attaching a label of a general adhesive sheet having a configuration in which a top paper, an adhesive layer, and a release sheet are sequentially laminated using an automatic labeler or the like is adopted.

However, a label provided with a water-soluble adhesive is
When a water-soluble adhesive is applied to the back surface of the base material, the label curls, and after sticking to the glass bottle, wrinkles and floating occur on the label, resulting in a defective label and spoiling the appearance. On the other hand, as for the label of the pressure-sensitive adhesive sheet having a general structure, the release sheet is usually peeled off and used, but the peeled release sheet is difficult to be collected and reused, and is almost always discarded. In recent years, attention has been paid to resource saving and environmental problems, and a heat-sensitive adhesive sheet that does not require a release sheet has been receiving attention.

Generally, a heat-sensitive adhesive is a thermoplastic resin,
It is composed of a solid plasticizer and the like. The heat-sensitive adhesive sheet has a structure in which a heat-sensitive adhesive is applied on one surface of a base material, and is usually used as a label by printing on the other surface of the base material. The heat-sensitive adhesive is non-adhesive at room temperature, but is activated and develops adhesiveness when heated with a labeler or an oven provided with a heating device. Usually, the activation temperature is 50 to 150 ° C., and the solid plasticizer in the heat-sensitive adhesive starts to melt in this temperature range to give the thermoplastic resin adhesiveness. Since the molten solid plasticizer slowly crystallizes, the stickiness is maintained for a long time. Therefore, the solid plasticizer is used while being adhered to a glass bottle or the like while having the stickiness.

Even if the heat-sensitive adhesive sheet is continuously adhered to the glass bottle with a labeler or the like provided with a heating device, a method of applying a water-soluble adhesive to the back surface of the label and adhering it to the glass bottle is the same. There is no problem of a bad label. In addition, there is an advantage that the release sheet is not used unlike the general pressure-sensitive adhesive sheet described above, and thus it can be produced at a low cost.
It is also advantageous from the viewpoint of resource saving and environmental problems.

However, when the heat-sensitive adhesive sheet is used as a label and attached to a glass bottle or the like having a small diameter such as an ampoule bottle, the heat-sensitive adhesive is completely solidified until the label is fixed to the bottle. There was a problem that the agent was cohesively broken and the edge of the label floated up from the ampoule bottle.

When the heat-sensitive adhesive sheet is attached to a material having low polarity such as polyethylene, the label is not removed after the once melted solid plasticizer is recrystallized and the adhesiveness of the heat-sensitive adhesive is deactivated. There was a problem that it easily fell off from polyethylene. In particular, when using a polyethylene squeeze bottle such as a ketchup container or an eye drop bottle, the problem of the label popping up or peeling off from the container when you press the part where the label is stuck when using it is a problem. there were.

[0008]

SUMMARY OF THE INVENTION According to the present invention, the end of the label does not rise even when it is attached to an ampoule bottle having a small diameter, and it can be adhered to a polyethylene container of low polarity for a long period of time. The present invention provides a heat-sensitive adhesive sheet.

[0009]

DISCLOSURE OF THE INVENTION The present invention is characterized in that a heat-sensitive adhesive layer containing a thermoplastic resin, a solid plasticizer and adhesive microspheres is provided on one surface of a substrate. It is a sheet. Furthermore, the present invention is the heat-sensitive adhesive sheet, wherein the adhesive microspheres have an average particle size of 10 to 60 μm.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The heat-sensitive adhesive used in the heat-sensitive adhesive sheet of the present invention contains a thermoplastic resin, a solid plasticizer and adhesive microspheres. Adhesive microspheres have adhesiveness at room temperature, the heat-sensitive adhesive sheet obtained by applying and drying the thermosensitive adhesive, the surface of the adhesive microspheres by a solid plasticizer and a thermoplastic resin. Non-sticky because it is covered. However, when the heat-sensitive adhesive sheet is activated by heating, the solid plasticizer is melted to give adhesiveness to the thermoplastic resin, and at the same time, the surface of the adhesive microspheres having adhesiveness is exposed. When sticking to a small diameter ampoule bottle etc. in such a state, the thermosensitive adhesive solidifies completely and the sticky microspheres fix the label on the ampoule bottle until the label is fixed on the ampoule bottle. Therefore, label floating due to cohesive failure of the heat-sensitive adhesive does not occur.

In addition, when it is attached to a polyethylene container which is required to have the suitability (also referred to as squeeze suitability) that the stuck label does not float or peel off from the container when the contents are pushed out by pressing the container at the time of use, it is solid. Even after the plasticizer is recrystallized and the thermoplastic resin loses its adhesiveness, the adhesive microspheres are exposed and the label is fixed to the polyethylene container. There is no problem that the label floats or drops off.

The types of thermoplastic resins contained in the heat-sensitive adhesive of the present invention include styrene-butadiene copolymer, styrene-isoprene copolymer, vinyl acetate-ethylene-styrene copolymer, vinyl acetate-ethylene. Copolymer, vinyl acetate-ethylene-vinyl chloride copolymer, vinyl acetate-acrylic acid ester copolymer, vinyl acetate-ethylene-acrylic acid ester copolymer, ethylene-vinyl chloride copolymer, (meth) acrylic acid Examples thereof include ester copolymers and acrylonitrile-butadiene copolymers. These thermoplastic resins are used alone or in combination.

The glass transition temperature of the thermoplastic resin is in the range of -35 to 70 ° C, preferably -10.
６０60 ° C. Further, it is more preferably 20 to 60 ° C. If the glass transition temperature of the thermoplastic resin is lower than -35 ° C, there is a problem that the thermoplastic resin has tackiness even at room temperature. On the other hand, when the temperature exceeds 70 ° C., when the heat-sensitive adhesive is applied to a substrate, the surface strength of the heat-sensitive adhesive-coated surface is weakened, and there is a problem that printability is poor when used as a label.

The solid plasticizer used in combination with the copolymer used as the thermoplastic resin in the heat-sensitive adhesive is:
Diphenyl phthalate, Dihexyl phthalate (melting point 65
℃), dicyclohexyl phthalate (melting point 63-65
° C), dihydroabietyl phthalate (melting point 65 ° C), dimethyl isophthalate (melting point 66 to 67 ° C), diisohexyl phthalate, sucrose benzoate (melting point 98 ° C),
Ethylene glycol dibenzoate (melting point 70 ° C), trimethylolethane tribenzoate (melting point 73 ° C), glyceride tribenzoate, pentaerythritol tetrabenzoate (melting point 95)
C), sucrose octaacetate (melting point 89 ° C.), tricyclohexyl citrate (melting point 57 ° C.), N-cyclohexyl-
Well-known benzoic acid, caprylic acid, citric acid, phthalic acid and phosphoric acid esters such as p-toluenesulfonamide (melting point 86 ° C.) and sulfonamide derivatives having a melting point of preferably 50 to 100 ° C. It is preferable to use one having a temperature of 60 to 80 ° C.

When a solid plasticizer having a melting point of less than 50 ° C. is used, there is a problem that blocking is likely to occur. Blocking of the heat-sensitive adhesive sheet means, for example, when the heat-sensitive adhesive sheet is stored in a wound state or in a state where many sheets are piled up in the summer or at a high temperature exceeding 40 ° C, the solid plasticizer begins to melt and heat. Since the thermoplastic resin is made to have tackiness, the heat-sensitive adhesive surface of the heat-sensitive adhesive sheet will adhere to the surface of the base material. The lower the melting point of the solid plasticizer, the easier the blocking. On the other hand, when the melting point of the solid plasticizer exceeds 100 ° C., there is a problem that it is difficult to activate by heating.

The solid plasticizer melts at a temperature equal to or higher than the melting point when it is activated by heating to plasticize the thermoplastic resin, and thus provides tackiness as a heat-sensitive adhesive. Since the duration of tackiness depends on the solid plasticizer used, it is appropriately selected and used. For example, it is preferable to use dicyclohexyl phthalate when the stickiness is prolonged. These solid plasticizers can be used alone or in combination of two or more.

The average particle size of the solid plasticizer is 1 to 8 μm.
m is preferable. If it is less than 1 μm, there is a problem that the blocking resistance is poor. Further, if it exceeds 8 μm, there is a problem that it takes time for the solid plasticizer to completely melt upon activation by heating. A more preferable average particle diameter is about 1 to 4 μm.

As a method for adjusting the average particle diameter of the solid plasticizer, the solid plasticizer, the dispersant and water are mixed and the mixture is appropriately pulverized by a ball mill, a sand mill or the like. Examples of the dispersant include methyl cellulose, carboxymethyl cellulose, polyvinyl alcohol, poly (meth) acrylate, polystyrene sulfonate,
Various water-soluble polymers such as gelatin and various surfactants such as anionic surfactants and nonionic surfactants can be used.

These dispersants can be used alone or in combination of two or more. The mixing ratio of the solid plasticizer and the dispersant is appropriately determined within a preferable range, but generally, the dispersant is 0.5 per 100 parts by weight of the solid plasticizer.
-10 solid parts by weight is preferred. It is more preferably 1 to 5 parts by weight solids. When the amount of the dispersant is less than 0.5 parts by weight, the solid plasticizer is insufficiently dispersed in water, and the finely divided primary particles cause reaggregation. Further, if it exceeds 10 parts by weight, there is a problem that the adhesive performance is deteriorated.

The adhesive microspheres used in the present invention include ethyl acrylate, propyl acrylate, n-butyl acrylate, isopropyl acrylate, n-octyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, nonyl acrylate, isononyl acrylate, lauryl. Acrylate, methylmethacrylate, propylmethacrylate, butylmethacrylate, 2-ethylhexylmethacrylate, isononylmethacrylate, laurylmethacrylate, etc. (meth) acrylic acid ester as a main component, these monomers and acrylic acid, methacrylic acid, itaconic acid, Crotonic acid, maleic acid, 2-hydroxyethyl (meth) acrylate,
Hydroxypropyl (meth) acrylate, N-methylol (meth) acrylamide, (meth) acrylamide, glycidyl (meth) acrylate, glycidyl ether (meth) acrylate, vinyl acetate, styrene,
(Meth) acrylonitrile, trimethylamine (meth)
Acrylamide, trimethylamine-p-vinylbenzimide, ammonium (meth) acrylate, sodium (meth) acrylate, N, N-dimethyl-N- (β
-(Meth) acryloxyethyl) ammonium propionate betaine, 1,1-dimethyl-1- (2-hydroxypropyl) amine (meth) acrylimide, 4,
4,9-Trimethyl-4-azonia-7-oxy-9-
Decene-1-sulfonate, 1,1-dimethyl-1-
It can be produced by copolymerizing a monomer such as (2,3-dihydroxypropyl) amine (meth) acrylimide into a sphere.

A specific manufacturing method is described in, for example, JP-A-50-2736 and JP-A-61-14827.
It can be produced by the suspension polymerization method described in, for example, JP-A-8. Further, a commercially available sticky microsphere produced by emulsion polymerization or the like can also be used.

Further, a removable pressure-sensitive adhesive comprising a pressure-sensitive adhesive microsphere and a binder can be used. When using a releasable pressure-sensitive adhesive that uses a thermoplastic resin such as an acrylic resin as a binder, the thermosensitive pressure-sensitive adhesive of the present invention can be obtained simply by blending a solid plasticizer. However, the thermoplastic resin used for the removable adhesive often has a poor adhesive function when used as a heat-sensitive adhesive. Therefore, when using the removable pressure-sensitive adhesive, it is preferable to further mix a thermoplastic resin having an excellent adhesive function as the heat-sensitive pressure-sensitive adhesive.

The average particle size of the adhesive microspheres used in the present invention is preferably 10 to 60 μm. If the average particle size is less than 10 μm, when it is attached to a glass bottle or a polyethylene container as a label, the solid plasticizer is recrystallized and the adhesiveness of the thermoplastic resin is deactivated and solidified, and then the adhesive microspheres are solidified. It will be buried in the part you did. Then, there is a problem that it is difficult to fix the label in a glass bottle or a polyethylene container because the adhesive microspheres are buried in the solidified portion. Further, if the average particle size is 60 μm or more, it is difficult to cover the surface of the adhesive microspheres with a solid plasticizer and a thermoplastic resin to make them non-adhesive, and there is a problem that blocking resistance is poor. Further, when the label is attached to an ampoule bottle having a small diameter, there is a problem that the label easily floats from the ampoule bottle.

The average particle size of the adhesive microspheres can be adjusted by changing the polymerization conditions. For example, if the amount of water or emulsifier used during the polymerization is increased, the average particle size becomes smaller, so the average particle size may be adjusted by the amount of water or emulsifier.

The mixing ratio of the thermoplastic resin, the solid plasticizer, and the adhesive microspheres in the heat-sensitive adhesive is 100 thermoplastic resin.
The solid plasticizer is 50 to 300 solid parts by weight and the adhesive microspheres are 10 to 400 parts by weight with respect to the solid parts by weight. Preferably, 100 to 250 parts by weight of the solid resin, 100 to 250 parts by weight of the solid plasticizer, and 30 to 200 of the adhesive microspheres are preferable.
Parts by weight. Incidentally, if the solid plasticizer is less than 50 parts by weight, there is a problem that the tackiness as a heat-sensitive adhesive is less likely to appear and the adhesion function is poor and the blocking resistance is poor. When the solid plasticizer is used in an amount of more than 300 parts by weight, there is a problem that the time for which the solid plasticizer has tackiness as a heat-sensitive adhesive becomes short. If the amount of the adhesive microspheres is less than 10 parts by weight, it is difficult to prevent the label from floating from the ampoule bottle. On the contrary, if the amount of the adhesive microspheres exceeds 400 parts by weight, it is difficult to cover the surface of the adhesive microspheres with a thermoplastic resin or a solid plasticizer to make them non-adhesive.

In order to further improve the adhesive function as the heat-sensitive adhesive, an appropriate amount of a commonly used tackifier such as rosin-based, phenol resin-based, terpene resin-based, petroleum resin-based may be added. Examples of rosin-based tackifiers include rosin abietic acid, hydrogenated products thereof and maleic acid adducts thereof, metal salts, glycerin, pentaerythritol, processed rosins such as ester compounds with alcohols such as ethylene glycol and diethylene glycol. To be Further, as the terpene-based tackifier, it is preferable to use a homopolymer of α-pinene, β-pinene, dipentene or the like, a copolymer thereof, a terpene phenol copolymer, and a water additive thereof.

The tackifier is preferably one having a softening point of 70 to 150 ° C. and an emulsion form. If the softening point is lower than 70 ° C., blocking tends to occur, and if it exceeds 150 ° C., it may be difficult to develop tackiness when heat-activated and used as a heat-sensitive adhesive sheet. When the tackifier is contained, the preferable compounding ratio of the tackifier is 10 to 150 solid parts by weight, preferably 30 to 1 solid part with respect to 100 parts by weight of the thermoplastic resin.
00 solid parts by weight. If it is less than 10 parts by weight, the effect of enhancing the adhesive function is poor, and if it exceeds 100 parts by weight, the blocking resistance is poor.

Further, in order to prevent blocking, an antiblocking agent in the form of powder or emulsion (eg starch, clay mineral, silica etc.) and a dispersion liquid of polyolefin fine particles may be contained. The amount of these antiblocking agents to be used is 10 to 100 parts by weight, preferably 20 to 50 parts by weight based on 100 parts by weight of the thermoplastic resin.
Parts by weight.

The heat-sensitive adhesive of the present invention is in the form of an aqueous dispersion containing a thermoplastic resin, a solid plasticizer, and adhesive microspheres as the main components of the solid content. As an optional ingredient,
A tackifier, an antiblocking agent, etc. may be added as necessary, but the solid content concentration of the emulsion as a heat-sensitive adhesive is preferably 20 to 80%. If the solid content concentration is less than 20% or more than 80%, it is difficult to control the coating amount when the heat-sensitive adhesive is coated by various coating devices. Further, the solid content concentration is preferably adjusted appropriately to a concentration suitable for the coating apparatus used.

The method for producing the heat-sensitive adhesive of the present invention is obtained by mixing the thermoplastic resin in the form of an emulsion, the solid plasticizer dispersed in water, and the adhesive microspheres and stirring the mixture until they are uniform. Further, it is preferable to first mix the sticky microspheres in a solid plasticizer dispersed in water, cover the surface of the sticky microspheres with the solid plasticizer, and then mix with the thermoplastic resin until uniform. This is because if the surface of the adhesive microspheres is covered with a solid plasticizer, blocking resistance will be more excellent. The temperature at the time of mixing may be a temperature lower than the melting point of the solid plasticizer, and is usually room temperature.

The coating amount of the heat-sensitive adhesive is preferably 5 to 40 g / m ^{2 in} dry weight. More preferably 10
Is about 30 g / m ² . Incidentally, if the coating amount is less than 5 g / m ² , there is a problem that when used as a label, a sufficient adhesive function cannot be obtained and the label cannot be used. On the other hand, when it exceeds 40 g / m ² , it takes time to heat and activate the heat-sensitive adhesive, and the adhesive function is saturated, resulting in poor economy.

The method for applying the heat-sensitive adhesive to the substrate is brush coating, spray coating, screen printing, gravure printing, offset printing, letterpress printing, Mayer bar coater, kiss roll coater, lip coater, direct roll coater. , An offset roll coater, a gravure roll coater, a reverse roll coater, a rod coater, a blade coater, an air knife coater, and the like. Drying can be carried out by a conventional method combined with the above-mentioned device for coating.

The drying should be carried out at a temperature lower than the melting point of the solid plasticizer used. This is because if the solid plasticizer is dried at a temperature higher than the melting point of the solid plasticizer, the solid plasticizer melts during the drying and the heat-sensitive adhesive layer becomes tacky. For the above reasons, the drying temperature is generally 5
It is preferably lower than 0 ° C.

The Beck smoothness of the heat-sensitive adhesive coated surface of the heat-sensitive adhesive sheet is 60 to 200 seconds, preferably 70.
It is preferably ˜150 seconds. Beck smoothness is 20
If it exceeds 0 seconds, there is a problem that the blocking resistance is poor. If the Beck's smoothness is less than 60 seconds, the adhesion between the heat-activated heat-sensitive adhesive sheet and the glass bottle or the like to be attached tends to deteriorate, and the adhesion function may deteriorate.

Examples of the material of the base material to which the heat-sensitive adhesive of the present invention is applied include papers, synthetic papers, films, metal foils, non-woven fabrics, woven fabrics, and sheets in which these are appropriately laminated. Of course, various layers such as a heat-sensitive recording layer, a pressure-sensitive recording layer, a thermal transfer image-receiving layer, an ink-jet recording layer, and a pigment coating layer may be provided on the surface of these substrates. On the other hand, on the surface to which the heat-sensitive adhesive is applied, a barrier layer may be provided to reinforce the strength or prevent the heat-sensitive adhesive from penetrating into the base material and preventing the adhesive function from deteriorating. When used as a label, printability and the like are required. In particular, when used as a label to be affixed to a glass bottle containing a liquid such as soft drink, alcoholic beverage, drug bottle or the like, it is preferable to use a substrate having excellent water resistance. Further, an ink or the like may be added to the heat-sensitive adhesive layer to color the heat-sensitive adhesive, or heat-expandable microspheres may be contained to adjust the adhesive function.

The heat-sensitive adhesive sheet is used by printing it on the surface of the base material and continuously adhering it with a labeler or the like provided with a heat activation device. It can be sufficiently applied even if it is used by sticking it to an ampoule bottle, which has been problematic up to now, or a squeeze bottle made of a material such as polyethylene such as ketchup or eye drop bottle.

[0037]

The present invention will be described in more detail with reference to the following examples, but it should be understood that the present invention is by no means restricted to such specific examples.
In the examples, "parts by weight" means "parts by weight" unless otherwise specified.

[Example 1] [Preparation of solid plasticizer] 100 parts by weight of dicyclohexyl phthalate (manufactured by Osaka Organic Chemical Industry Co., Ltd.) as a solid plasticizer, and a nonionic surfactant (trade name: "Neugen EA" as a dispersant. -120 ", manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) 2.
4 parts by weight and water were uniformly mixed to a concentration of 62%, and the mixture was pulverized using a ball mill until a dispersion liquid of dicyclohexyl phthalate having an average particle diameter of 2.0 μm was obtained.

[Preparation of Thermosensitive Adhesive] In the dispersion of the solid plasticizer prepared above, adhesive microspheres (average particle diameter 45 μm
m, a copolymer containing 2-ethylhexyl acrylate as a main component obtained by suspension polymerization, and then mixed with ethylene-vinyl chloride copolymer (glass transition temperature 20 ° C., trade name: “Sumi” as a thermoplastic resin. Elite 1210 ",
(Sumitomo Chemical Co., Ltd.) and water were mixed and stirred until uniform to prepare a heat-sensitive adhesive having a concentration of 50%. The compounding ratio at this time was 200 parts by weight of the solid plasticizer and 100 parts by weight of the adhesive microspheres with respect to 100 parts by weight of the thermoplastic resin. The average particle diameter of the adhesive microspheres was observed by an electron microscope.

[Preparation of Heat-sensitive Adhesive Sheet] Mitsubo 84.9
Double-sided art paper with g / m ² (Product name: “Kanfuji both sides <73
>", Manufactured by Shin-Oji Paper Co., Ltd.) with a bar coater on one side, and the heat-sensitive adhesive obtained above is dried at 1 wt.
A heat-sensitive adhesive sheet was obtained by applying 6.5 g / m ² and drying.

[Example 2] In the preparation of a heat-sensitive adhesive, an adhesive microsphere which is a copolymer containing 2-ethylhexyl acrylate as a main component and obtained by suspension polymerization having an average particle diameter of 5 µm was used. A heat-sensitive adhesive was prepared in the same manner as in Example 1 to obtain a heat-sensitive adhesive sheet.

[Example 3] 2 obtained by suspension polymerization with an average particle size of 70 µm in the preparation of a heat-sensitive adhesive
A heat-sensitive adhesive was prepared in the same manner as in Example 1 except that the adhesive microspheres, which were a copolymer containing ethylhexyl acrylate as a main component, were used to obtain a heat-sensitive adhesive sheet.

Example 4 n was obtained by suspension polymerization with an average particle size of 40 μm in the preparation of a heat-sensitive adhesive.
A heat-sensitive pressure-sensitive adhesive sheet was obtained by preparing a heat-sensitive pressure-sensitive adhesive in the same manner as in Example 1 except that the pressure-sensitive adhesive microspheres that were a copolymer containing butyl acrylate as a main component were used.

[Example 5] In preparation of a heat-sensitive adhesive, a removable pressure-sensitive adhesive (trade name: "Nikazol S355") containing adhesive microspheres which are 2-ethylhexyl acrylate copolymer having an average particle diameter of 50 µm. , Manufactured by Nippon Carbide Industry Co., Ltd., ethylene as a thermoplastic resin
Vinyl chloride copolymer (glass transition temperature 20 ° C, trade name:
"Sumi Elite 1210", manufactured by Sumitomo Chemical Co., Ltd.), the solid plasticizer prepared in Example 1 and water were mixed and stirred until uniform to prepare a heat-sensitive adhesive having a concentration of 50%. The compounding ratio at this time was 200 parts by weight of the solid plasticizer and 50 parts by weight of the adhesive microspheres with respect to 100 parts by weight of the thermoplastic resin.

Comparative Example 1 A thermosensitive adhesive sheet was obtained in the same manner as in Example 1 except that the adhesive microspheres were not mixed in the preparation of the thermosensitive adhesive.

"Evaluation" The obtained pressure-sensitive adhesive sheet was subjected to label floating and evaluated for adhesiveness to a polyethylene container. Table 1 shows the results.

"Label Floating" The obtained heat-sensitive adhesive sheet was activated by heating for 10 seconds in an oven heated to 110 ° C. to form a label having a width of 20 mm and a length of 30 mm, and a diameter of 11
The label was affixed so as to go around the mm ampoule bottle for medical use, and after 24 hours, the state in which the edge of the label floated from the medical ampoule bottle was observed and evaluated according to the following criteria. [Evaluation Criteria] O: No floating occurred at all. Δ: The edge of the label is slightly raised, but there is no problem in practical use. X: The label floats, which is a practical problem.

"Adhesiveness to Polyethylene Container" The obtained heat-sensitive adhesive sheet was activated by heating in an oven heated to 110 ° C. for 10 seconds and attached to a polyethylene eye drop container. After one month, after the solid plasticizer was recrystallized and the heat-sensitive adhesive deactivated the adhesiveness, whether the label was peeled off by pressing the eyedrop container by hand was evaluated according to the following criteria. [Evaluation Criteria] ◯: The label is completely fixed on the eye drop container. Δ: The edge of the label is slightly peeled off, but there is no problem in practical use. X: The label is easily peeled off.

[0049]

[Table 1]

[0050]

As is apparent from Table 1, the heat-sensitive adhesive sheet of the present invention does not lift the label from the ampoule bottle even when attached to an ampoule bottle having a small diameter, and is excellent in polyethylene. It is a heat-sensitive adhesive sheet showing excellent adhesiveness.

Claims (2)

[Claims] 1. A heat-sensitive adhesive sheet comprising a substrate and a heat-sensitive adhesive layer containing a thermoplastic resin, a solid plasticizer and adhesive microspheres provided on one surface of the substrate. 2. The average particle size of the adhesive microspheres is 10 to 60 μm.
The heat-sensitive adhesive sheet according to claim 1, which is m.