JP2000008007A - Heat-sensitive tacky sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a heat-sensitive tacky sheet capable of readily releasing even after passing for a prescribed period after attaching the sheet. SOLUTION: This heat-sensitive tacky sheet forms a heat-sensitive tacky agent layer containing a thermoplastic resin, a tackiness-imparting agent and a solid plasticizer on at least either one surface of a substrate sheet. The adhesiveness at the point of time after passing through for 6 month from attachment when attached to an adherent is >=100 g/25 mm and <600 g/25 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive adhesive sheet used as a so-called delayed tack label, and more particularly, to a heat-sensitive adhesive sheet which can be easily peeled off even after a predetermined period has passed since it was applied. The present invention relates to a pressure-sensitive adhesive sheet.

[0002]

2. Description of the Related Art Conventionally, when a label is applied to a container such as a bottle or a polyethylene terephthalate (hereinafter, referred to as "PET") bottle, an adhesive is applied onto a label substrate and simultaneously applied to the container. A glue label, an adhesive label in which an adhesive and a release paper are sequentially formed on a label substrate, and the like are used.

[0003] However, the use of glue labels requires much trouble such as management of the viscosity of the pressure-sensitive adhesive and cleaning of a machine for applying the pressure-sensitive adhesive. Further, when an adhesive label formed with a release paper is used, a large amount of release paper peeled off from the label is generated as garbage, which requires time and effort in disposal and is not preferable from the viewpoint of resource saving.

[0004] In order to solve such problems,
A delayed tack label made of a heat-sensitive adhesive sheet is known. Delayed tack labels are formed by forming a heat-sensitive adhesive layer on a label substrate that is non-adhesive at room temperature but develops adhesiveness by heating, eliminating the need for release paper, and can be easily achieved by simply heating. It has the advantage that it can be affixed to a container. The heat-sensitive adhesive layer is
Usually, a glass transition temperature is about 0 to 30 ° C., a thermoplastic resin is dispersed with particles of a solid plasticizer and, if necessary, a tackifier, and the solid plasticizer melted by heating converts the thermoplastic resin. It is plasticized to exhibit tackiness.

[0005] However, the conventional heat-sensitive adhesive sheet tends to increase with time in peeling strength after heating and pasting, so that it cannot be easily peeled off when the sheet needs to be peeled off later. Would. If the sheet is difficult to peel off as described above, there arises a problem that the sheet cannot be used for a bottle which is supposed to be collected and reused, such as a beer bottle. In addition, when affixed to a PET bottle, it becomes impossible to recycle it after use, which is not preferable because resource saving is being sought.

JP-A-6-259016 discloses a method in which a water-soluble or water-dispersible aqueous coating layer and a water-insoluble hydrophobic coating layer are provided between a base sheet and a heat-sensitive adhesive layer. A heat-sensitive adhesive label that can be peeled off by hot water or steam is disclosed. In addition, Japanese Unexamined Patent Publication No.
JP-A-259017 discloses a heat-sensitive adhesive that can be peeled off with hot water or steam by providing a heat-expandable paint layer and a water-insoluble hydrophobic paint layer between a base sheet and a heat-sensitive adhesive layer. Label is disclosed. Although these heat-sensitive adhesive labels can be peeled off with hot water or steam, they are inferior in water resistance, and because they are multilayered, the production becomes complicated and the production cost increases.

Japanese Patent Application Laid-Open No. 6-314062 discloses a heat-sensitive adhesive which can be immersed in an aqueous solvent and peeled off by including a heat-expandable microcapsule and a water-soluble polymer in the heat-sensitive adhesive layer. Label is disclosed. With this heat-sensitive adhesive label, the releasability can be improved to some extent. However, the adhesive may sometimes remain on the adherend, and is poor in water resistance because it contains a water-soluble polymer.

JP-A-8-231929 discloses that a heat-sensitive release layer made of a polymer material and a solid plasticizer is provided between a substrate sheet and a heat-sensitive adhesive layer, and the heat-sensitive release layer is heated. An adhesive sheet which is softened so as to be easily peeled off from an adherend is disclosed. However, in this pressure-sensitive adhesive sheet, a part of the heat-sensitive release layer may remain on the adherend after peeling. Further, the adhesive strength between the base sheet and the heat-sensitive release layer is reduced, and as a result, the adhesive strength between the pressure-sensitive adhesive sheet and the adherend is reduced.

[0009]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to remove the adhesive layer without using hot water, steam, an aqueous solvent or the like, and to prevent the adhesive layer from remaining on the adherend. Another object of the present invention is to provide a heat-sensitive adhesive sheet that can be easily peeled off even after a predetermined period has passed since the application.

[0010]

Means for Solving the Problems The heat-sensitive adhesive sheet of the present invention is based on a heat-sensitive adhesive layer containing a thermoplastic resin, a tackifier for exhibiting initial tackiness, and a solid plasticizer. It is formed on at least one surface of the material sheet, and the solid plasticizer is melted by heating, whereby the thermoplastic resin is plasticized to exhibit adhesiveness.

According to the present invention, a heat-sensitive adhesive sheet that has developed adhesiveness by heating is adhered to an adherend, and the adhesive strength after 6 months has passed is 100 g / 25 mm to 60 g.
It is made based on the finding that the above-mentioned problem can be solved if it is less than 0 g / 25 mm. Here, the adhesive strength is indicated by “g / 25 mm”,
This display shows that 2 kg attached to the adherend with a load of 2 kg
A 5 mm wide heat-sensitive adhesive sheet is pulled at a pulling speed of 300 mm.
/ Min, a tensile force required for peeling from an adherend at a peel angle of 180 ° in terms of grams.

[0012]

Embodiments of the present invention will be described below. The heat-sensitive adhesive sheet of the present invention has a heat-sensitive adhesive layer formed on at least one surface of the base sheet, and the heat-sensitive adhesive layer contains a thermoplastic resin, a tackifier, and a solid plasticizer. Contains.

[0013] The adhesive strength at the time of 6 months after the heat-sensitive adhesive sheet is applied is 100 g / 25 mm or more and 600 g / 2.
In order to be less than 5 mm, a combination of a thermoplastic resin, a tackifier and a solid plasticizer and their mixing ratio,
The thickness of the heat-sensitive adhesive layer is important.

The thermoplastic resin used in the present invention includes, for example, a homo- or copolymer of (meth) acrylate, a styrene- (meth) acrylate copolymer, and vinyl acetate- (meth) acryl. Acid ester copolymer, ethylene- (meth) acrylate ester copolymer,
Ethylene- (meth) acrylic acid copolymer, (meth) acrylic acid ester- (meth) acrylic acid copolymer, styrene-acrylonitrile- (meth) acrylic acid ester copolymer, styrene- (meth) acrylic acid ester- (Meth) acrylic acid copolymer, styrene-acrylonitrile- (meth) acrylic acid ester- (meth) acrylic acid copolymer, ethylene-vinyl acetate- (meth) acrylic acid ester copolymer, vinylpyrrolidone- (meth) Acrylic ester copolymer, styrene-butadiene- (meth)
Acrylic polymer containing (meth) acrylic acid or its ester as a monomer such as acrylic acid copolymer; vinyl acetate resin containing vinyl acetate as a monomer such as vinyl acetate resin and ethylene-vinyl acetate copolymer Polymer: styrene-butadiene copolymer, isobutylene resin, isobutylene-isoprene copolymer, butadiene resin, styrene-
Synthetic rubber such as isoprene copolymer and acrylonitrile-butadiene copolymer; natural rubber; ethylene-vinyl chloride copolymer, vinyl chloride-vinylidene chloride copolymer, vinylpyrrolidone-styrene copolymer, chlorinated propylene resin, urethane Resin, ethyl cellulose and the like. These thermoplastic resins may be used alone or in combination of two or more.

[0015] Among the above thermoplastic resins, the adhesive strength at the time of 6 months after the application of the heat-sensitive adhesive sheet is 100 g / g.
From the viewpoint of being 25 mm or more and less than 600 g / 25 mm, preferred thermoplastic resins include acrylic polymers [for example, acrylic polymers containing (meth) acrylic acid ester as a monomer], vinyl acetate polymers, Synthetic rubber, natural rubber and the like are included. Among the acrylic polymers, particularly, acrylate-methacrylate copolymers (for example, C _2-20 alkyl acrylate-C _1-4 alkyl methacrylate copolymer), acrylate-methacrylate Acid ester
(Meth) acrylic acid copolymer (for example, acrylic acid C
_2-20 alkyl ester-methacrylic acid C _1-4 alkyl ester- (meth) acrylic acid copolymer), acrylate-styrene- (meth) acrylic acid copolymer (for example, C _2-20 alkyl acrylate) -Styrene-
Acrylics containing (meth) acrylic acid copolymer) and other acrylates (eg, C _2-20 alkyl acrylates) and methacrylates (eg, C _1-4 alkyl methacrylates) or styrene as comonomers. An acid copolymer is exemplified.

Glass transition temperature (Tg) of thermoplastic resin
Can be appropriately selected in consideration of the type of the adherend and the like in a range that does not impair the adhesiveness and the blocking resistance when the pressure-sensitive adhesive sheet is used, and is usually about −10 to 70 ° C. When the glass transition temperature is lower than −10 ° C., the blocking resistance tends to decrease. On the other hand, if the glass transition temperature is too high, the adhesiveness tends to decrease.

The solid plasticizer that can be used in the present invention is:
It can be melted at the time of heating to plasticize the above-mentioned thermoplastic resin and exhibit tackiness. For example, diphenyl phthalate, dihexyl phthalate, diisohexyl phthalate, dicyclohexyl phthalate, dicyclohexyl phthalate, di (3,5)
-Dimethylcyclohexyl), di (3,3,5) phthalate
-Trimethylcyclohexyl), di (2,2, phthalate)
6-trimethylcyclohexyl), dimenthyl phthalate, dibornyl phthalate, dihydroabiethyl phthalate, dinaphthyl phthalate, etc .; isophthalic esters such as dimethyl isophthalate, dibenzyl isophthalate, dicyclohexyl isophthalate; terephthalic acid Dimethyl, dibenzyl terephthalate, dicyclohexyl terephthalate, diterephthalate (3,3,5
Terephthalic acid esters such as trimethylcyclohexyl); benzoic acid scroll, ethylene glycol dibenzoate, trimethylolethane tribenzoate, glyceride tribenzoate, pentaerythroate tetrabenzoate, scroll octaacetic acid, tricyclohexyl citrate, N -Cyclohexyl-p-toluenesulfonamide, alkylated and arylated phosphoric acid, urea derivatives, paraffin chloride and the like. These solid plasticizers may be used in combination of two or more.

Among the above-mentioned solid plasticizers, the adhesive strength at the time of 6 months after the heat-sensitive adhesive sheet is applied is 100 g / 2.
From the viewpoint of being 5 mm or more and less than 600 g / 25 mm, preferred solid plasticizers include dicyclohexyl phthalate and di (3,3,5-trimethylcyclohexyl) phthalate.

The content of the solid plasticizer is such that the adhesive strength after 6 months from the application of the heat-sensitive adhesive sheet is 100.
g / 25 mm or more and less than 600 g / 25 mm, but is usually 100 parts by weight or more and 1000 parts by weight or less with respect to 100 parts by weight of the thermoplastic resin.
It is preferably from 900 to 900 parts by weight, more preferably from 200 to 800 parts by weight. If the content of the solid plasticizer is less than 100 parts by weight, sufficient tackiness will not be exhibited during heating, and if it is more than 1000 parts by weight, cohesive strength will be reduced and sufficient adhesive strength will not be exhibited.

As tackifiers that can be used in the present invention,
For example, terpene resin, aliphatic petroleum resin, aromatic petroleum resin, cumarone-indene resin, styrene resin, phenol resin, terpene-phenol resin, rosin derivative (rosin, polymerized rosin, hydrogenated rosin and their glycerin, Esters with pentaerythritol, resin acid dimer, etc.) and xylene resins. Two or more of these tackifiers may be used in combination.

The content of the tackifier is not particularly limited, and the adhesive strength after 6 months from the application of the heat-sensitive adhesive sheet is 100 g / 25 mm or more and 600 g or more.
/ 25 mm and is appropriately determined according to the combination of the thermoplastic resin and the solid plasticizer. Generally, the amount is from 10 to 600 parts by weight, preferably from 20 to 500 parts by weight, per 100 parts by weight of the thermoplastic resin.

The thickness of the heat-sensitive adhesive layer is, for example, 5 μm or more and 18 μm or less, preferably 6 μm or more and 15 μm or less, and particularly preferably 7 μm or more and 12 μm or less. If the thickness of the pressure-sensitive adhesive layer is too small, it will be difficult to obtain sufficient adhesive strength. Conversely, if the thickness of the pressure-sensitive adhesive layer is too large, the adhesive force becomes too large, and the pressure-sensitive adhesive sheet cannot be peeled off.

In the heat-sensitive adhesive of the present invention, other than the above-mentioned additives, conventional additives such as a film-forming aid, a defoaming agent, a coating improver, a thickener, a lubricant are used as long as the properties are not impaired. And stabilizers (antioxidants, ultraviolet absorbers, heat stabilizers, etc.), antistatic agents, antiblocking agents (inorganic particles, organic particles, etc.) and the like.

The heat-sensitive adhesive sheet of the present invention can also be obtained by applying an aqueous dispersion obtained by dispersing the above-mentioned heat-sensitive adhesive in water using a dispersant on a base sheet and drying. The dispersant that can be used for preparing the aqueous dispersion is not particularly limited, and any of conventionally known anionic or nonionic dispersants can be used. Examples of the anionic dispersant include a carboxylate, a sulfate, a sulfonate and a phosphate, and an ammonium carboxylate is preferred. Examples of the nonionic dispersant include a polyethylene glycol type dispersant and a polyhydric alcohol type dispersant.

As the method of dispersing in water, various conventionally known methods can be adopted. For example, a method in which each component of the heat-sensitive adhesive is mixed in advance and then dispersed in water, a method in which a solid plasticizer is dispersed in a thermoplastic resin emulsion or a tackifier emulsion and then these emulsions are mixed, Disperse the agent in water,
For example, a method of mixing a thermoplastic resin emulsion and a tackifier emulsion with the dispersion may be used. Examples of the method of dispersing the solid plasticizer in the above-mentioned emulsion or water include a method of dispersing a molten solid plasticizer, a method of dispersing a solid plasticizer while making it into a fine powder, a method of dispersing a solid plasticizer that is made into a fine powder, etc. Can be exemplified.

The average particle size of the solid plasticizer in the aqueous dispersion is preferably 0.5 μm or more and 20 μm or less, more preferably 1 μm or more and 15 μm or less. When the average particle size is smaller than 0.5 μm, the resulting heat-sensitive adhesive sheet sticks to each other when stored at a high temperature, so-called blocking occurs, or the solid plasticizer takes a long time to be pulverized, and productivity decreases. There is a fear. If the average particle size exceeds 20 μm, the coated surface may be rough and the quality as a label may be reduced.

The heat-sensitive adhesive layer in the heat-sensitive adhesive sheet of the present invention can be formed by applying a heat-sensitive adhesive to at least one surface of a substrate. The application of the heat-sensitive adhesive can be performed by dissolving the heat-sensitive adhesive in an organic solvent or by heating and melting the heat-sensitive adhesive. In the case of an aqueous dispersion prepared with a heat-sensitive adhesive and a dispersant, the heat-sensitive adhesive layer can be formed by applying this to at least one surface of the base material and drying it. . Examples of the method of applying the heat-sensitive adhesive or the aqueous dispersion thereof include a method using a roll coater, an air knife coater, a blade coater, a rod coater, a bar coater, a comma coater, a gravure coater, a silk screen coater, and the like. Can be.

As the substrate on which the heat-sensitive adhesive of the present invention is applied, paper, coated paper, plastic film, wood, cloth,
Nonwoven fabrics, metals and the like can be mentioned. Examples of the polymer constituting the plastic film include polyolefins such as polyethylene and polypropylene, ethylene-vinyl acetate copolymer, polyvinyl chloride, polyvinyl chloride-vinyl acetate copolymer, poly (meth) acrylate, polystyrene, and the like. Polyvinyl alcohol, ethylene-vinyl alcohol copolymer, cellulose derivative of cellulose acetate, polyester (polyalkylene terephthalate such as polyethylene terephthalate and polybutylene terephthalate, polyalkylene naphthalate such as polyethylene naphthalate and polybutylene naphthalate),
Polycarbonate, polyamide (polyamide 6, polyamide 6/6, polyamide 6/10, polyamide 6/12
And the like, polyester amide, polyether, polyimide, polyamide imide, polyether ester, and the like. Further, copolymers, blends, and crosslinked products thereof may be used.

The heat-sensitive adhesive sheet of the present invention is obtained by forming a heat-sensitive adhesive layer containing a thermoplastic resin, a tackifier and a solid plasticizer on at least one surface of a substrate sheet as described above. When the adhesive is applied to an adherend by heating to develop adhesiveness, the adhesive strength is adjusted so as to be 100 g / 25 mm or more and less than 600 g / 25 mm after 6 months from the application. If the adhesive strength is less than 100 g / 25 mm after 6 months from application, the bottle or PET
Undesirably, problems such as peeling of the heat-sensitive adhesive sheet occur until the bottles are lined up at the store or during display at the store. In addition, the adhesive strength after 6 months from the application is 6
If the thickness is more than 00 g / 25 mm, the sheet cannot be peeled off, which hinders reuse of the bottle and recycling of the PET bottle. Here, the reason for judging the adhesive strength after pasting at the time of six months is that most of the bottles, PET bottles and the like that are filled are consumed within this period.

[0030]

The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto.

(Example 1) [Preparation of aqueous dispersion of solid plasticizer] 100 parts by weight of dicyclohexyl phthalate (melting point 65 ° C) as a solid plasticizer and an anionic surfactant (ammonium polycarboxylate) as a dispersant 12 parts by weight and 80 parts by weight of water were mixed and pulverized using a ball mill until the average particle diameter became 2.2 μm to obtain an aqueous dispersion of dicyclohexyl phthalate.

The average particle size of the solid plasticizer was measured using a laser diffraction particle size distribution analyzer (LA-5 manufactured by Horiba, Ltd.).
00) and described as a median diameter (the same applies to the following Examples and Comparative Examples).

[Preparation of heat-sensitive adhesive] In the aqueous dispersion of dicyclohexyl phthalate prepared above, an aqueous emulsion of an acrylic polymer (2-ethylhexyl acrylate-methyl methacrylate-acrylic acid copolymer) was used as a thermoplastic resin. And an aqueous dispersion of a terpene-based tackifier as a tackifier and water are mixed and stirred until uniform, and an emulsion of a heat-sensitive adhesive having a solid content concentration of 50% by weight is obtained. I got At this time, the mixing ratio was 1 solid plasticizer (dicyclohexyl phthalate).
Thermoplastic resin (acrylic polymer) per 100 parts by weight
It was 31 parts by weight and 11 parts by weight of a tackifier (terpene resin).

[Thermosensitive Pressure-sensitive Adhesive Sheet] The amount of the heat-sensitive pressure-sensitive adhesive emulsion prepared above was 10 g / m ² after drying using a bar coater on the base paper surface of a single art paper having a basis weight of 84.9 g / m ^2. m ^2, and dried at 40 ° C. for 2 minutes to obtain a heat-sensitive adhesive sheet of Example 1. Table 1 shows the composition and coating amount of the heat-sensitive adhesive in this example.

(Comparative Example 1) [Preparation of heat-sensitive adhesive] In the aqueous dispersion of dicyclohexyl phthalate prepared in Example 1, an aqueous emulsion of an acrylic polymer (2-ethylhexyl acrylate-methyl) was used as the thermoplastic resin. A methacrylate-acrylic acid copolymer, glass transition temperature Tg: 25 ° C.), an aqueous dispersion of a terpene-based tackifier as a tackifier and water are mixed and stirred until uniform, and the solid content concentration is 50% by weight. To obtain a heat-sensitive adhesive emulsion. The mixing ratio at this time was 9 parts by weight of the thermoplastic resin (acrylic polymer) and 31 parts by weight of the tackifier (terpene resin) with respect to 100 parts by weight of the solid plasticizer (dicyclohexyl phthalate).

[Thermosensitive Pressure-sensitive Adhesive Sheet] The amount of the heat-sensitive pressure-sensitive adhesive emulsion prepared above was 10 g / m ² after drying using a bar coater on the base paper surface of a single art paper having a basis weight of 84.9 g / m ^2. m ^2, and dried at 40 ° C. for 2 minutes to obtain a heat-sensitive adhesive sheet of Comparative Example 1. Table 1 shows the composition and coating amount of the heat-sensitive adhesive in this comparative example.

(Comparative Example 2) [Preparation of heat-sensitive adhesive] In the aqueous dispersion of dicyclohexyl phthalate prepared in Example 1, an aqueous emulsion of an acrylic polymer (2-ethylhexyl acrylate-methyl) was used as a thermoplastic resin. A mixture of methacrylate-acrylic acid co-child, glass transition temperature Tg: 25 ° C.), an aqueous dispersion of a rosin-based tackifier as a tackifier, and water are stirred until uniform, and the solid content concentration is 50% by weight. % Of a heat-sensitive adhesive was obtained. The mixing ratio at this time is
The thermoplastic resin (acrylic polymer) was 31 parts by weight and the tackifier (rosin derivative) was 11 parts by weight based on 100 parts by weight of the solid plasticizer (dicyclohexyl phthalate).

[Thermosensitive Pressure-sensitive Adhesive Sheet] The amount of the heat-sensitive pressure-sensitive adhesive emulsion prepared above after drying with a bar coater on a base paper of single art paper having a basis weight of 84.9 g / m ² was 10 g / m ^2. m ² and dried at 40 ° C. for 2 minutes to obtain a heat-sensitive adhesive sheet of Comparative Example 2. Table 1 shows the composition and coating amount of the heat-sensitive adhesive in this comparative example.

(Comparative Example 3) [Preparation of heat-sensitive adhesive] In the aqueous dispersion of dicyclohexyl phthalate prepared in Example 1, an aqueous emulsion of an acrylic polymer (2-ethylhexyl acrylate-methyl) was used as the thermoplastic resin. A methacrylate-acrylic acid copolymer, glass transition temperature Tg: 25 ° C.), an aqueous dispersion of a petroleum resin-based tackifier as a tackifier and water are mixed and stirred until uniform, and the solid content concentration is 50% by weight. To obtain a heat-sensitive adhesive emulsion. The mixing ratio at this time is
Based on 100 parts by weight of the solid plasticizer (dicyclohexyl phthalate), 31 parts by weight of the thermoplastic resin (acrylic polymer) and 11 parts by weight of the tackifier (petroleum resin) were used.

[Thermosensitive Pressure-sensitive Adhesive Sheet] A coating amount of the heat-sensitive pressure-sensitive adhesive emulsion prepared above after drying with a bar coater on the base paper surface of a single art paper having a basis weight of 84.9 g / m ² was 10 g / m ^2. m ² and dried at 40 ° C. for 2 minutes to obtain a heat-sensitive adhesive sheet of Comparative Example 3. Table 1 shows the composition and coating amount of the heat-sensitive adhesive in this comparative example.

(Example 2) [Preparation of aqueous dispersion of solid plasticizer] 100 parts by weight of bis (cis-3,3,5-trimethylcyclohexyl) phthalate (melting point: 93 ° C) as a solid plasticizer, and anion as a dispersant Surfactant (Polyammonium polycarboxylate) 1
An aqueous dispersion of bis (cis-3,3,5-trimethylcyclohexyl) phthalate is obtained by mixing 2 parts by weight and 80 parts by weight of water and pulverizing the mixture using a ball mill until the average particle diameter becomes 2.6 μm. Was.

[Preparation of Thermosensitive Adhesive] An acrylic polymer (2-ethylhexyl acrylate) as a thermoplastic resin was added to the aqueous dispersion of bis (cis-3,3,5-trimethylcyclohexyl) phthalate prepared above. -Methyl methacrylate-styrene-acrylic acid copolymer, an aqueous emulsion having a glass transition temperature Tg: 28 ° C.), an aqueous dispersion of a terpene phenol resin as a tackifier and water are added, and the mixture is stirred until uniform, and the solid content is reduced. A heat-sensitive adhesive having a concentration of 50% by weight was obtained. At this time, the blending ratio was such that 17 parts by weight of the thermoplastic resin (acrylic polymer) and 100 parts by weight of the solid plasticizer [bis (cis-3,3,5-trimethylcyclohexyl) phthalate], and the tackifier (terpene) Resin) was 26 parts by weight.

[Thermosensitive Pressure-sensitive Adhesive Sheet] The emulsion of the heat-sensitive pressure-sensitive adhesive prepared above was applied to a base paper surface of a single art paper having a basis weight of 84.9 g / m ² by using a bar coater after drying with a coating amount of 8 g / m ^2, and dried at 60 ° C. for 2 minutes to obtain a heat-sensitive adhesive sheet of Example 2. Table 1 shows the composition and coating amount of the heat-sensitive adhesive in this example.

Comparative Example 4 The coating amount of the emulsion of the heat-sensitive adhesive prepared in Example 2 after drying with a bar coater on the base paper surface of a single art paper having a basis weight of 84.9 g / m ² was 4 The solution was coated to a thickness of 0.5 g / m ² and dried at 60 ° C. for 2 minutes to obtain a heat-sensitive adhesive sheet of Comparative Example 4. Table 1 shows the composition and coating amount of the heat-sensitive adhesive in this comparative example.

(Comparative Example 5) The coating amount of the emulsion of the heat-sensitive adhesive prepared in Example 2 after drying with a bar coater on the base paper surface of a single art paper having a basis weight of 84.9 g / m ² was 2.
Coating was performed so as to be 0 g / m ^2, and the coating was dried at 60 ° C. for 4 minutes to obtain a heat-sensitive adhesive sheet of Comparative Example 5. Table 1 shows the composition and coating amount of the heat-sensitive adhesive in this comparative example.

[0046]

[Table 1]

(Evaluation of Characteristics of Heat-Sensitive Adhesive Sheet) The characteristics of the heat-sensitive adhesive sheets obtained in Examples and Comparative Examples were evaluated as follows.

[Adhesive strength test] The obtained heat-sensitive adhesive sheet was cut into a width of 25 mm and a length of 125 mm to obtain a test piece. The test piece was heated at 120 ° C. for 30 seconds to develop adhesiveness, and then a glass plate (Micro sll manufactured by Iwaki Glass Co., Ltd.)
ide Glass), and applied by reciprocating once with a rubber roll under a load of 2 kg. This is 23
It was left in an atmosphere of 60 ° C. and 60% RH, and after one day and six months, an adhesive strength test was performed. The adhesive strength test was carried out using a tensile tester (Tensilon UCT-5T manufactured by Orientec Co., Ltd.) using a tensile speed of 300 mm / min and a peel angle of 180 °.
The measurement was performed by measuring the adhesive force.

[Releasability Test] A test piece was attached to a glass plate in the same manner as in the adhesive strength test described above, and the test piece was peeled off by hand, and the peelability was determined according to the following criteria.

：: Peeled off without leaving the adhesive on the glass surface. △: Partially left the adhesive on the glass surface and peeled. ×: Peeled off before the test. Or, the paper (base sheet) was torn.

Table 2 shows the results of the adhesive strength test and the peelability test.
It was shown to. As is clear from Table 2, the heat-sensitive adhesive sheets obtained in the examples have practically no problem adhesive strength after 1 day and 6 months, and leave the adhesive on the glass. It can be peeled off without. On the other hand, the heat-sensitive adhesive sheet of the comparative example has a very large adhesive force after 6 months, and is substantially impossible to peel off, or is peeled off by leaving it alone after 6 months. It turns out that it is not practical.

[0052]

[Table 2]

(Example 3) Rat [F344 / N (SP
F), male, experimental age: 42 days old, Japan SLC, Inc.], the effects of the four phthalate esters on testis were searched for as follows.

A group of 10 rats was tested for each condition (n = 10). The animals were fasted for approximately 16 hours before administration, and administration was performed in the morning. Feeding is CRF-1
(Manufactured by Oriental Yeast Co., Ltd.)
Time went. Water was supplied freely from Himeji City tap water.

(Experiment 1) Bis (cis-3,3,5-trimethylcyclohexyl) phthalate (hereinafter referred to as "TMCO
To 2 g of LP), 8 ml of olive oil (Yoshida Pharmaceutical Co., Ltd., lot 998521) was added, and the mixture was dissolved by heating at 100 ° C. for about 30 minutes.
A g / ml TMCOL-P solution was prepared. Similarly, 200 mg of dicyclohexyl phthalate (hereinafter abbreviated as “DCHP”) (manufactured by Wako Pure Chemical Industries, Ltd.) was used.
/ Ml of DCHP solution was prepared.

In addition, 7.96 ml of olive oil (Yoshida Pharmaceutical, lot 998521) is added to 2 g of bis (2-ethylhexyl) phthalate (hereinafter abbreviated as "DOP") (manufactured by Aldrich Chemical Industries).
Was added and mixed with a vortex to prepare a 200 mg / ml DOP solution. Furthermore, dibutyl phthalate (hereinafter abbreviated as “DBP”) (Wako Pure Chemical Industries, Ltd.)
Was added to 2 g of the above-prepared product, and mixed with a vortex to prepare a 200 mg / ml DBP solution.

These phthalate solutions were prepared on the day of administration, and kept at 37 ° C. until immediately before administration.

Using each solution obtained above, TMCO
1000 mg / L of LP, DCHP, DOP and DBP
At a dose of kg (5 ml / kg), rats were administered continuously (oral administration) for 7 days. A control to which olive oil was administered instead of the administration of a phthalate ester was used as a control.

During continuous administration for 7 days, the body weight was measured every day, and on the day following the last day (day 8), after decapitation and blood removal, the testes and epididymis were excised and the wet weight was measured. Further, the excised testis was used as a Bouin fixative (saturated picric acid 15,
After fixation in formalin 3 and glacial acetic acid 1) for 48 hours, 70%
After washing twice with ethyl alcohol and embedding in paraffin, the sections were sliced and stained with HE to prepare HE-stained specimens, which were subjected to histological search.

As a result, TMCOL-P, DOP and DCOL
No significant change was observed in the weight change value of the BP group as compared with the control group, but the DCHP group was administered on day 4 (p <0.05) and on day 6 (p <0.01). On the 7th day (p <0.05) and the 8th day (p <0.05), a significant weight loss of 92 to 94% was observed as compared with the control group. In addition, the testicular weight was TMCOL-
In the case of P, DCHP and DOP, no significant weight loss was observed as compared with the control group, but the DBP group had a significant weight loss (49
%, P <0.001). However, regarding the epididymis, no significant weight change was observed in any of the administration groups as compared with the control group.

On the other hand, regarding the pathological search of testis tissue, T
In all cases of the MCOL-P administration group, no change in testis tissue was observed as compared with the control group. But DCH
In the P and DOP groups, bilateral and unilateral degeneration and atrophy of seminiferous tubules were observed in 4 and 5 cases, respectively. DBP
In the group, testicular tissue showed severe changes, and bilateral and diffuse atrophy of seminiferous tubules was observed in all cases. 1 point each for a few of the atrophied seminiferous tubules on the specimen (+), those that are extensive but not diffuse (++), and those that show a change in diffuseness (++) When the degree of influence on testis was evaluated by giving a score of 2 points and 3 points, control, TMCOL-P, DCHP, DO
The scores of the P and DBP groups are 0 points, 0 points, respectively.
5, 10, and 26 points.

(Experiment 2) 12 g for 3 g of TMCOL-P
1 of olive oil (Yoshida Pharmaceutical Co., Ltd., lot 998521) was added and dissolved by heating at 100 ° C. for about 30 minutes to prepare a 200 mg / ml TMCOL-P solution. Similarly, DCHP (manufactured by Wako Pure Chemical Industries, Ltd.)
Was used to prepare a 200 mg / ml DCHP solution.

Also, 11.94 ml of olive oil (Yoshida Pharmaceutical, lot 998521) was added to 3 g of DOP (manufactured by Aldrich Chemical Industries),
Vortexing was performed to prepare a 200 mg / ml DOP solution. In addition, DBP (Wako Pure Chemical Industries, Ltd.)
Was added to 3 g of the above product, and mixed with vortex to prepare a 200 mg / ml DBP solution.

These phthalate solutions were prepared on the day of administration and kept at 37 ° C. until immediately before administration.

Using each solution obtained above, TMCO
2000 mg / L of LP, DCHP, DOP and DBP
Rats were administered (oral administration) at a dose of kg (10 ml / kg) for 7 consecutive days. A control to which olive oil was administered instead of the administration of a phthalate ester was used as a control.

During the continuous administration for 7 days, the body weight was measured every day, and on the day following the last day (day 8), after decapitation and blood removal, the testes, epididymis and liver were removed and the wet weight was measured.

As a result, no significant change was observed in the change in body weight of TMCOL-P as compared with the control group, but the body weight of the DCHP, DOP and DBP groups was significantly larger than that of the control group. A decrease was observed. DOP
And significant weight loss in the DBP group from day 5 of administration (p <0.05 and p <0.01, respectively) and continued to decrease gradually until the last day of the experiment (day 8).
The change in body weight of the DOP and DBP groups on the last day of the experiment was 85% (p <
0.01) and 83% (p <0.01). DC
In the HP group, one patient died on the 5th day of administration, and the general condition was piloerection, browning of coat, squatting, weakness, etc., and the administration was stopped. However, on days 6 and 7
On day two and one died, respectively. The weight loss in the DCHP group was minimal on day 6 of administration (75%, P <0.0
1), but then showed a tendency to recover.

The testes weight was determined using TMCOL-
Except for P (86%, no significant difference), all of the DCHP, DOP and DBP groups showed a significant decrease in testis weight,
The extent of the decrease was 4% of the weight of the control group, respectively.
6% (p <0.01), 56% (p <0.01) and 3
8% (p <0.001). Furthermore, as for the epididymis, TMCOL-P (81
%, No significant difference), except DCHP, DOP and DBP
A significant weight loss was observed in all of the groups, and the degree of the reduction was 58% of the weight of the control group (p <
0.05), 71% (p <0.05) and 56% (p <
0.01). For liver weight, TM
DCH excluding COL-P (111%, no significant difference)
A significant increase in liver weight was observed in all of the P, DOP and DBP groups, and the extent of the increase was 131% (p <0.001) and 175% (p
<0.001) and 146% (p <0.001).

[0069]

The heat-sensitive adhesive sheet of the present invention has an adhesive strength of 100 g / at 6 months after the application, including the case where the heat-sensitive adhesive sheet is applied to an adherend after heating to develop the adhesiveness. 2
Since it is in the range of 5 mm or more and less than 600 g / 25 mm,
It can be easily peeled off. Moreover, it can be peeled off without using hot water, steam, aqueous solvent, etc.,
It can be used for beer bottles that are collected and used many times, PET bottles that are recycled as resources, and the like.

Claims (4)

[Claims] 1. A heat-sensitive adhesive sheet comprising a heat-sensitive adhesive layer containing a thermoplastic resin, a tackifier and a solid plasticizer formed on at least one surface of a substrate sheet, wherein the heat-sensitive adhesive sheet comprises When the sheet is heated so as to exhibit tackiness and then applied to an adherend, the adhesive strength at the time of 6 months after application is 100 g / 25 mm or more and 600 g / 25 mm.
A heat-sensitive adhesive sheet, wherein 2. The heat-sensitive adhesive layer comprises a thermoplastic resin,
A heat-sensitive adhesive sheet formed by applying an aqueous dispersion of a heat-sensitive adhesive containing a tackifier and a solid plasticizer to at least one surface of a base sheet and drying the applied dispersion. 3. The heat-sensitive adhesive sheet according to claim 1, wherein the thermoplastic resin is an acrylic polymer. 4. The heat-sensitive adhesive sheet according to claim 1, wherein the solid plasticizer is dicyclohexyl phthalate.