JPH09235528A - Heat-sensitive tacky agent and heat-sensitive tacky sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject tacky agent containing a specific oil-absorbing pigment at a specific ratio, capable of simply improving blocking resistance without lowering adhesive function and capable of providing a heat-sensitive tacky sheet excellent in printability. SOLUTION: This heat-sensitive tacky agent is obtained by adding (C) oil- absorbing pigment having >=100ml/100g oil absorption amount (based on JIS-K-5101) (preferably calcined caoline, amorphous silica or amorphous silica) in an amount of 0.5-50 solid pts.wt. based on 100 solid pts.wt. component B to a heat-sensitive tacky agent consisting essentially of (A) a thermoplastic resin (e.g. vinyl acetate-ethylene-styrene copolymer) and (B) a solid plasticizer (preferably dihexyl phthalate having 50-100 deg.C melting point). Glass transition temperature of the component A is preferably -10 to 70 deg.C. Average particle diameter of the component B is preferably 1-10μm and average particle diameter of the component C is preferably <=15μm. When the tacky agent is applied onto the substrate, the coating amount is preferably 10-35g/m<2> .

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a heat-sensitive adhesive which is non-adhesive at room temperature but shows tackiness when heated, and a heat-sensitive adhesive obtained by applying and drying the heat-sensitive adhesive. Regarding the seat.

[0002]

2. Description of the Related Art Conventionally, labels such as soft drinks, alcoholic beverages, and glass bottles such as chemical bottles are labeled with a water-soluble adhesive such as casein or starch on the back surface of a substrate by an automatic labeler or the like. There is adopted a method of attaching, or a method of attaching a label of a general adhesive sheet having a structure in which a top paper, an adhesive layer and a release sheet are sequentially laminated using an automatic labeler or the like. However, for a label with a water-soluble adhesive, when the water-soluble adhesive is applied to the back surface of the base material, the label curls and wrinkles or floats occur on the label after it is attached to the glass bottle, resulting in a defective label and spoiling its appearance. There was a problem. On the other hand, a label of a pressure-sensitive adhesive sheet having a general structure is usually used by peeling off the release sheet, but the peeled release sheet is difficult to collect and reuse, 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 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 between 50 ° C and 150 ° C
In this temperature range, the solid plasticizer in the heat-sensitive adhesive starts to melt and gives the thermoplastic resin an adhesive property. The melted solid plasticizer is crystallized slowly and the stickiness is maintained for a long time. Therefore, it is used by sticking it to a glass bottle or the like while having the stickiness.

Even if the heat-sensitive adhesive sheet is continuously stuck to the glass bottle with a labeler or the like provided with a heating device, it is like a method of applying a water-soluble adhesive to the back surface of the label and sticking it to the glass bottle. 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, the heat-sensitive adhesive sheet is often stored in a wound state or in a state where several sheets are stacked, and in this case, blocking occurs when the temperature is higher than room temperature. There is a problem. In order to solve this problem, for example, a method of adding or mixing an inorganic substance (Japanese Patent Laid-Open No. 2-282050)
Alternatively, a method of preventing the blocking by protecting the surface of the solid plasticizer in the heat-sensitive adhesive with an inorganic compound or colloidal particles and suppressing softening of the solid plasticizer (Japanese Patent Laid-Open No. 6-5722).
No. 3, JP-A-6-100847, JP-A-6-
No. 1004848) and the like have been proposed.

However, the blocking resistance is not sufficient by simply adding an ordinary inorganic substance. Further, when the solid plasticizer is protected by an inorganic compound or colloidal particles, when the heat-sensitive adhesive is heated to a temperature of 80 ° C. or lower to be activated,
It takes a long time to melt and diffuse the solid plasticizer, and the adhesiveness of the heat-sensitive adhesive hardly appears, and the adhesive function of the heat-sensitive adhesive sheet is deteriorated.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a method which makes it possible to easily improve the blocking resistance of a heat-sensitive adhesive sheet without lowering its adhesive function.

[0008]

Means for Solving the Problems As a result of intensive studies on the heat-sensitive adhesive, the present inventors have found that the heat-sensitive adhesive contains an oil-absorptive pigment in a specific ratio, so that one surface of the substrate is coated with the oil-absorbing pigment. It was found that it is possible to easily improve the blocking resistance without lowering the adhesive function of the heat-sensitive adhesive sheet obtained by applying and drying the heat-sensitive adhesive.

[0009] That is, the present invention, in a heat-sensitive adhesive mainly composed of a thermoplastic resin and a solid plasticizer, the oil absorption (JIS-K-
(Based on 5101) is 100 ml / 100 g or more, and the oil-absorbing pigment is 0.5 to 100 parts by weight of the solid plasticizer.
The heat-sensitive adhesive is characterized by containing 50 parts by weight of solids. . Dispersed particles of the oil-absorbing pigment contained in the heat-sensitive adhesive are the above-mentioned heat-sensitive adhesives having an average particle diameter of 15 μm or less. . The content of the oil-absorbing pigment is 2 to 20 solid parts by weight with respect to 100 parts by weight of the solid plasticizer, or the heat-sensitive adhesive described in (1). . The oil-absorptive pigment is at least one selected from calcined kaolin, amorphous silica, and amorphous alumina. . It is a heat-sensitive adhesive sheet obtained by applying the heat-sensitive adhesive described in any one of to 1 to at least one surface of a substrate and drying. . It is the heat-sensitive adhesive sheet according to [1], which is subjected to a printing treatment on the surface on which the heat-sensitive adhesive is applied and dried.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is a heat-sensitive adhesive characterized by containing an oil-absorbing pigment and a heat-sensitive adhesive sheet using the same. The use of the oil-absorbing pigment makes it possible to improve the blocking resistance of the heat-sensitive adhesive sheet, and the reason for this is considered as follows. The reason why blocking occurs when the heat-sensitive adhesive sheet is stored at a temperature higher than room temperature is considered to be that the solid plasticizer in the heat-sensitive adhesive melts slightly to give adhesiveness to the thermoplastic resin. To be It is considered that when the oil-absorbing pigment is present in the pressure-sensitive adhesive, the slightly melted solid plasticizer is quickly absorbed by the oil-absorbing pigment and prevents the thermoplastic resin from being plasticized.

Further, a heat-sensitive adhesive sheet using a heat-sensitive adhesive having an oil-absorbing pigment blended in a specific ratio has a surface on which the heat-sensitive adhesive is provided is much more printable than conventional products. It turns out that Conventional heat-sensitive adhesive sheets have poor ink drying properties during printing, which limits the amount of ink used and the printing speed, and even when the ink is dried at low temperatures, the solid plasticizer slightly elutes and heat Printing was scarcely performed because of giving tackiness to the plastic resin. The heat-sensitive adhesive sheet of the present invention is a solid in which the oil-absorbing pigment contained in the heat-sensitive adhesive significantly improves printability (ink drying property) because it absorbs ink, and the oil-absorbing pigment is slightly melted. It is considered that this is because the plasticizer quickly absorbs the oil-absorbing pigment and can prevent the thermoplastic resin from being plasticized.

The oil-absorptive pigment used in the present invention is an oil-absorption amount (JIS-
(Based on K-5101) is a pigment of 100 ml / 100 g or more. Specifically, kaolin, calcined kaolin, calcium carbonate, calcium silicate, talc, silica, alumina, diatomaceous earth, calcined diatomaceous earth, mica, magnesium oxide, magnesium carbonate, aluminosilicate, activated clay, montmorillonite, minerals such as zeolite. Pigments, porous pigments, carbon black, polystyrene resins, urea resins,
Acrylic resin, melamine resin, benzoguanamine resin,
Other known or official pigments such as fine particles such as organic pigments, porous fine particles, and hollow fine particles have an oil absorption of 100 m.
One or two or more of 1/100 g or more are appropriately used.

In particular, calcined kaolin, amorphous silica, amorphous alumina, calcium silicate, magnesium oxide, activated clay, zeolite, carbon black and the like having high oil absorbency are preferable, and among them, calcined kaolin, amorphous silica and amorphous alumina are preferable. The best. The oil absorption is 500
Pigments that exceed ml / 100 g are not very common and are economically ineffective. By the way, the oil absorption is 1
If the amount is less than 00 ml / 100 g, there is no blocking prevention ability and the problem of the present invention cannot be solved.

Among the above oil-absorbing pigments, the dispersed particles of the pigment when dispersed in a heat-sensitive adhesive are primary particles having high porosity, secondary particles which are aggregates thereof, or porous particles. It is preferable to take any form of secondary particles rich in porosity formed by secondary aggregation of poor primary particles. An oil-absorbing pigment having such a form and having a pore volume of dispersed particles (mercury method) of 0.5 ml / g or more is
Particularly, it is preferably used since it has an excellent function of preventing blocking. That is, when the pressure-sensitive adhesive layer is formed, if it is rich in porosity, it can absorb the melted solid plasticizer quickly, and thus exhibits an excellent anti-blocking function.

Further, the oil absorbing pigment used in the present invention is
If the average particle size of dispersed particles in the pressure-sensitive adhesive exceeds 15 μm, the adhesive function of the heat-sensitive pressure-sensitive adhesive may be deteriorated.
It is preferably 15 μm or less. Further, particles having an average particle size of dispersed particles of less than 0.1 μm are not suitable for the present invention because they have little porosity. The average particle size of the oil absorbing pigment is measured by a laser diffraction / scattering method.

The method of adding these oil-absorbing pigments is not particularly limited, and an oil-absorbing pigment previously dispersed in water may be mixed with the heat-sensitive adhesive, or the oil-absorbing pigment may be directly absorbed in the heat-sensitive adhesive. It is also possible to add a functional pigment and disperse it by stirring. Also, the heat-sensitive adhesive can be prepared by adding and dispersing the oil-absorbing pigment to the emulsion of the thermoplastic resin or the dispersion of the solid plasticizer and then mixing them.
Further, an oil-absorbing pigment can be added to a commercially available heat-sensitive adhesive.

The content of the oil-absorbing pigment in the present invention is 0.5 to 50 solid parts by weight, preferably 2 to 20 solid parts by weight, based on 100 parts by weight of the solid plasticizer. By the way,
If it is less than 2 solid parts by weight, the desired effect of the present invention is little obtained, and if it is less than 0.5 solid part by weight, the desired effect of the present invention cannot be obtained. Further, if it exceeds 20 solid parts by weight, the adhesive function tends to deteriorate, and if it exceeds 50 solid part by weight, a sufficient adhesive function cannot be obtained.

The type of thermoplastic resin used in the heat-sensitive adhesive of the present invention includes 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 ester copolymer, styrene-
Isoprene copolymer, styrene-butadiene copolymer,
Examples thereof include acrylonitrile-butadiene copolymer. These thermoplastic resins are used alone or in combination.

The glass transition temperature of the thermoplastic resin is in the range of −35 to 80 ° C., more preferably −10 to 10.
70 ° C. The glass transition temperature of the thermoplastic resin is -35.
If it is lower than 0 ° C, there is a problem that it has tackiness even at room temperature and is inferior in blocking resistance. Further, when the glass transition temperature exceeds 80 ° C., when the heat-sensitive adhesive is applied to a substrate, the surface strength of the heat-sensitive adhesive-coated surface becomes weak, and the printability on the substrate when used as a label is poor. There's a problem.

The type of solid plasticizer used in the heat-sensitive adhesive of the present invention includes 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.), N-cyclohexyl-p-toluenesulfonamide (melting point 86).
° C), sucrose benzoate (melting point 98 ° C), ethylene glycol dibenzoate (melting point 70 ° C), trimethylolethane tribenzoate (melting point 73 ° C), pentaerythritol tetrabenzoate (melting point 95 ° C), sucrose octaacetate. (Melting point 89
C.), tricyclohexyl citrate (melting point 57.degree. C.) and the like having a melting point of 50 to 100.degree.
If the melting point is less than 50 ° C, the blocking resistance is poor and 1
If it exceeds 00 ° 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 activated by heating to plasticize the thermoplastic resin, and thus provides tackiness as a heat-sensitive adhesive, but the duration of tackiness varies depending on the solid plasticizer. It is preferable to use dicyclohexyl phthalate when the stickiness is prolonged. The solid plasticizers may be used alone or in combination of two or more.

The average particle size of the solid plasticizer is 1-10.
μm is preferred. By the way, if the average particle size is less than 1 μm, the blocking resistance is poor, and if it exceeds 10 μm, it takes time for the solid plasticizer to melt when it is activated by heating and used as a label, and the tackiness as a heat-sensitive adhesive hardly appears. There is a problem.

As a method for making the solid plasticizer have the above-mentioned average particle diameter, 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. As the dispersant, for example, methyl cellulose, carboxymethyl cellulose, polyvinyl alcohol, acrylic acid derivatives, sulfonic acid derivatives, maleic anhydride derivatives, various water-soluble polymers such as gelatin, anionic surfactants, nonionic surfactants, etc. Various surfactants can be used alone or in combination. The mixing ratio of the solid plasticizer and the dispersant is 100 parts by weight of the solid plasticizer and 0.
5 to 10 parts by weight solids are preferred. More preferably 1-5
Solid parts by weight. 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. Also, 10
If it exceeds the solid weight part, there is a problem that the adhesive performance is deteriorated. The blending ratio of the thermoplastic resin and the solid plasticizer in the heat-sensitive adhesive of the present invention is 15 to 200 solid parts by weight of the thermoplastic resin relative to 100 solid parts by weight of the solid plasticizer. Incidentally, when the total amount of the thermoplastic resins exceeds 200 solid parts by weight, there is a problem that the tackiness as a heat-sensitive adhesive is less likely to appear and the adhesive function is poor. When the thermoplastic resin is less than 15 parts by weight, there is a problem that the duration of tackiness as a heat-sensitive adhesive becomes short.

As the heat-sensitive adhesive, in addition to a thermoplastic resin and a solid plasticizer, a rosin-based tackifier, a phenol resin-based tackifier, a terpene resin-based tackifier, a xylene-based tackifier, and a petroleum resin-based tackifier. A tackifier such as a tackifier may be included to adjust the adhesive function. In this case, 3 to 100 parts by weight of the solid plasticizer, the tackifier is 3 to.
It is preferable to add 100 solid parts by weight. If the amount of the tackifier is less than 5 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.

If necessary, a colorant such as ink may be added to the heat-sensitive adhesive to color the adhesive, or heat-expandable microspheres may be contained to adjust the adhesive function.
Further, auxiliary substances such as waxes, protective colloids such as PVA, organic solvents and the like can be added as appropriate. In addition, the oil absorption is 100 as long as the quality such as the adhesive strength of the present invention is not impaired.
A pigment less than 100 ml / ml may be added.

The heat-sensitive adhesive obtained in this way is
Heat-sensitive adhesive layer coated and dried on at least one side of the substrate
Is formed. For the coating amount of heat-sensitive adhesive,
5-50g / m by weight^TwoIs preferred. More preferably 1
0-35g / m^TwoIt is a degree. By the way, the applied amount is 5g / m.
^TwoIf it is less than, it is a sufficient adhesive machine when used as a label.
There is a problem that it cannot be used as a label because
You. On the other hand, 50 g / m ^TwoExceeds the heat-sensitive adhesive
It takes time to heat and activate, and the adhesive function
Saturated and poor in economy.

As the method for applying the heat-sensitive adhesive to the substrate, brush coating, spray coating, screen printing, gravure printing, offset printing, letterpress printing, Meyer bar coater, kiss roll coater, lip coater, direct roll coater are used. , 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. The temperature of the heat-sensitive adhesive during coating must be lower than the melting point of the solid plasticizer used. This is because when the temperature is higher than the melting point of the solid plasticizer, the solid plasticizer melts and the heat-sensitive adhesive layer becomes tacky. Generally, the temperature of the adhesive is
It is preferably 50 ° C. or lower.

The drying can be carried out by a conventional method combined with the above-mentioned apparatus for coating. When drying,
It must be carried out below 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, it is generally preferable that the drying temperature is 50 ° C. or lower.

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. Needless to say, various layers such as a heat-sensitive recording layer, a pressure-sensitive recording layer, a thermal transfer image-receiving layer, an inkjet recording layer, and a pigment coating layer may be provided on the surface of these base materials. On the other hand, the surface to which the heat-sensitive adhesive is applied may be provided with a barrier layer to reinforce the strength or prevent the heat-sensitive adhesive from penetrating into the substrate and deteriorating the adhesive function. When used as a label, printability and the like are required. In particular, when used as a label to be attached to a glass bottle containing a liquid such as soft drink, alcoholic beverage, and chemical bottle, it is preferable to use a substrate having excellent water resistance.

The heat-sensitive adhesive sheet of the present invention has extremely excellent blocking resistance, but the heat-sensitive adhesive layer has excellent printability as compared with conventional products. As a printing method for the heat-sensitive adhesive layer, various known printing methods such as letterpress printing, flexographic printing, dry offset printing, gravure printing, gravure offset printing, offset printing, screen printing can be used, but in any method Also, when drying at a temperature higher than the melting point of the solid plasticizer in the drying step after printing, the solid plasticizer melts during drying and the heat-sensitive adhesive layer becomes tacky, so the drying temperature is the solid plasticizer. Below the melting point of
It is preferable that the temperature is not higher than ° C.

[0030]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.
In the examples, "parts by weight" means "parts by weight of solid" unless otherwise specified. Further, the oil-absorbing pigment used was observed with a microscope to determine whether it had porosity, and it was also described in the examples.

[Preparation of Solid Plasticizer] 100 parts by weight of dicyclohexyl phthalate (melting point: 64.7 ° C., manufactured by Osaka Organic Chemical Industry Co., Ltd.) as the solid plasticizer (1), and a nonionic surfactant (trade name) as a dispersant. : Neugen EA-120
(Daiichi Kogyo Seiyaku Co., Ltd.) and 5 parts by weight of water were uniformly mixed to a concentration of 62% and pulverized with a ball mill until the average particle size became 3.5 μm.

As the solid plasticizer (2), N-cyclohexyl-p-toluenesulfonamide (melting point 86 ° C., Lan
100 parts by weight of a caster), 5 parts by weight of a nonionic surfactant (trade name: Neugen EA-120, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) as a dispersant, and water are uniformly mixed to a concentration of 62%, and a ball mill is used. Average particle size of 1.5μ
It was crushed until it reached m.

[Preparation of Thermosensitive Adhesive] Example 1 As a thermoplastic resin, an ethylene-vinyl chloride copolymer having a glass transition temperature of 20 ° C. (trade name “Sumieryte 121
0 ", manufactured by Sumitomo Chemical Co., Ltd.), and porous calcined kaolin (trade name" Ansilex ", manufactured by Engelhard Minerals, oil absorption amount 110 ml / 100 g, average particle size 2) 0.5 .mu.m) was added and stirred for 1 hour to disperse the mixture, and then 100 parts by weight of the solid plasticizer (1) was mixed to prepare a heat-sensitive adhesive having a solid content concentration of 50%.

[Preparation of Heat-Sensitive Adhesive Sheet] Mitsubo 84.9
g / m ² single-sided art paper (brand name "Kanto single-sided <73
>", Manufactured by Shin-Oji Paper Co., Ltd.), the heat-sensitive adhesive obtained above was applied at a dry weight of 32 g / m ² using a reverse roll coater, and dried to obtain a heat-sensitive adhesive sheet.

Example 2 3 parts by weight of the oil-absorptive pigment of Example 1 was porous amorphous silica (trade name "Sylysia 310", manufactured by Nippon Silysia Ltd., oil absorption amount 310 ml / 100 g, average particle diameter 2.5 μm). A heat-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the above was changed to.

EXAMPLE 3 Porous amorphous alumina (trade name "AKP-G030", manufactured by Sumitomo Chemical Co., Ltd., oil absorption 280 ml / 100 g, average particle diameter 2.5 μm) was used as the oil-absorbing pigment of Example 1.
A heat-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the amount was changed to 0 part by weight.

Example 4 15 parts by weight of the oil-absorptive pigment of Example 1 was added to a porous activated clay (trade name "Shilton LP-75", manufactured by Mizusawa Chemical Industry Co., Ltd., oil absorption amount 250 ml / 100 g, average particle diameter 10 μm). A heat-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the above was changed to.

Example 5 A porous calcium silicate (trade name "Florite R", manufactured by Tokuyama Soda Co., Ltd., oil absorption 5 was used as the oil absorbing pigment of Example 1).
A heat-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the amount was changed to 3 parts by weight (00 ml / 100 g, average particle diameter 40 μm).

Example 6 The oil absorbing pigment of Example 1 was changed to 15 parts by weight of porous amorphous silica (trade name "Sylysia 470", manufactured by Nippon Silysia Ltd., oil absorption amount 180 ml / 100 g, average particle size 20 μm). A heat-sensitive adhesive sheet was obtained in the same manner as in Example 1 except for the above.

Example 7 To the heat-sensitive adhesive prepared in Example 6, 5 parts by weight of a rosin-based tackifier (trade name "Super Ester E-710", manufactured by Arakawa Chemical Industry Co., Ltd.) was added and solidified. Concentration 4
A heat-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that 5% of the heat-sensitive adhesive was obtained.

Example 8 The oil-absorbing pigment of Example 1 was used as an amorphous silica having a slightly poor porosity (trade name "Mizukasil P527", manufactured by Mizusawa Chemical Co., Ltd., oil absorption 170 ml / 100 g, average particle size 2.
5 μm) A heat-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the amount was changed to 3 parts by weight.

Example 9 A heat-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the amount of calcined kaolin added was changed to 45 parts by weight.

Example 10 A heat-sensitive adhesive sheet was obtained in the same manner as in Example 2 except that the amount of amorphous silica added was changed to 1 part by weight.

Comparative Example 1 A heat-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the amount of calcined kaolin added was changed to 60 parts by weight.

Comparative Example 2 Except that the oil absorbing pigment was not added in Example 1,
A heat-sensitive adhesive sheet was obtained in the same manner as in Example 1.

Comparative Example 3 Kaolin (trade name "Ultra White 90", manufactured by Engel Hard Minerals, in place of the oil absorbing pigment of Example 1
Oil absorption 40ml / 100g, average particle size 2.5μm) 1
A heat-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that 5 parts by weight was used.

Comparative Example 4 3 parts by weight of amorphous silica (trade name "Sylysia 740", manufactured by Nippon Silysia Ltd., oil absorption 85 ml / 100 g, average particle size 4 μm) was used in place of the oil absorbing pigment of Example 1. In the same manner as in Example 1, a heat-sensitive adhesive sheet was obtained.

Example 11 [Preparation of heat-sensitive adhesive] 70 parts by weight of SBR having a glass transition temperature of 9 ° C. as a thermoplastic resin (trade name “P4626”, manufactured by Sumitomo Dow Co., Ltd.) is a solid plasticizer (2). 100
By mixing 10 parts by weight, 10 parts by weight of porous calcined kaolin (trade name "Ansilex") is added as an oil-absorbing pigment, and the mixture is stirred for 1 hour to disperse it to obtain a heat-sensitive adhesive having a solid content concentration of 55%. Prepared. [Preparation of heat-sensitive adhesive sheet] A heat-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the above heat-sensitive adhesive was used.

Comparative Example 5 A heat-sensitive adhesive sheet was obtained in the same manner as in Example 11 except that 10 parts by weight of kaolin (trade name "Ultra White 90") was used in place of the oil absorbing pigment of Example 11.

Example 12 [Preparation of heat-sensitive adhesive] A commercially available heat-sensitive adhesive (trade name) was prepared by dispersing 5 parts by weight of porous amorphous silica (trade name "Sylysia 310") as an oil-absorbing pigment in water. "Heat Magic DW1040" manufactured by Toyo Ink Mfg. Co., Ltd., the content of dicyclohexyl phthalate in the total solid content is about 60 to 70.
%) 100 parts by weight to prepare a heat-sensitive adhesive having a solid content concentration of 40%. [Preparation of heat-sensitive adhesive sheet] A heat-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the above heat-sensitive adhesive was used.

Example 13 A heat-sensitive adhesive sheet was obtained in the same manner as in Example 12, except that the amount of amorphous silica added was changed to 10 parts by weight.

Example 14 In Example 12, a commercially available heat-sensitive adhesive (trade name "Cybinol X195-009E", manufactured by Saiden Chemical Co., Ltd., content of dicyclohexyl phthalate in total solid content of about 60 to 70%) was used. A heat-sensitive adhesive sheet was obtained in the same manner as in Example 12 except that it was used.

Comparative Example 6 A heat-sensitive adhesive sheet was prepared in the same manner as in Example 12, except that the commercially available heat-sensitive adhesive (trade name "Heat Magic DW1040") was used without adding the oil-absorbing pigment. Got

Comparative Example 7 A heat-sensitive adhesive sheet was obtained in the same manner as in Example 12, except that 20 parts by weight of kaolin (trade name "Ultra White 90") was used in place of the oil absorbing pigment of Example 12.

Comparative Example 8 A heat-sensitive adhesive sheet was obtained in the same manner as in Example 12, except that 40 parts by weight of kaolin (trade name "Ultra White 90") was used in place of the oil absorbing pigment of Example 12.

Comparative Example 9 Commercially available heat-sensitive adhesive without adding an oil-absorbing pigment in Example 14 (trade name "Cybinol X195-009E")
A heat-sensitive adhesive sheet was obtained in the same manner as in Example 14 except that was used as it was.

"Evaluation" The heat-sensitive adhesive sheet obtained was evaluated for adhesive function, blocking resistance, and printability of the adhesive-coated surface, and the results are shown in Table 1.

[Adhesive Function] A heat-sensitive adhesive sheet was placed at 120 ° C.
It was heat-activated for 15 seconds in an oven heated to 1, and after 1 minute of heat activation, it was attached to a glass plate. After 2 hours, measure the adhesive strength at an angle of 180 ° C. and a speed of 0.3 m / min,
It was judged according to the following criteria. ⊚: The adhesive force is 800 g / 25 mm or more, and the adhesive force is excellent. ◯: Adhesive strength is 500 to 800 g / 25 mm, and there is no practical problem. Δ: Adhesive strength is 300 to 500 g / 25 mm, which is somewhat problematic in practical use. X: The adhesive strength is less than 300 g / 25 mm, which is a problem in practical use.

[Blocking Resistance] The heat-sensitive adhesive sheet was wound up and treated at 50 ° C. for 7 days to evaluate the occurrence of blocking. A: Very good with no blocking. A: Excellent with almost no blocking. C: A little blocking occurs, but there is no practical problem. D: There is some practical problem because of blocking. E: Blocking is severe and there is a practical problem.

[Printability] Ink for sheet offset (manufactured by Dainippon Ink and Chemicals, Gr.
af-G black) 0.3 cc is printed on the heat-sensitive adhesive-coated surface of the heat-sensitive adhesive sheet, and fine paper is overlaid on the print surface immediately after printing, 5 minutes after printing, and 10 minutes after printing. In addition, the ink density transferred to the high-quality paper was pressed under a constant pressure and judged according to the following criteria. A: Ink hardly transferred after 5 minutes. ◯: The ink hardly transferred after 10 minutes. Δ: The transfer density after 10 minutes is about half the transfer density of the ink immediately after printing. X: The transfer density after 10 minutes is slightly thin with respect to the transfer density of the ink immediately after printing.

[Comprehensive Evaluation] From the results of evaluation of the adhesive function, blocking resistance, and printability of the heat-sensitive adhesive sheet, the one having particularly excellent quality was A, the one having excellent quality was B, and the one having no practical problem was C. A comprehensive evaluation was performed by setting D as a problem in practical use and E as a problem in practical use. Table 1 shows the results.

[0062]

[Table 1]

As is clear from Table 1, the oil absorption is 100 m.
Each of the examples containing 0.5 to 50 parts by weight of the oil-absorbing pigment of 1/100 g or more based on 100 parts by weight is excellent in adhesion function, blocking resistance, and printability. This means that Comparative Example 1 using an oil-absorptive pigment in an excessive amount and Comparative Examples 3, 4, 5, using a pigment having a low oil absorption amount.
It can be seen by comparing with Nos. 7, 8 and Comparative Examples 2, 6, 9 in which no pigment was used.

In particular, the calcined kaolin, amorphous silica, and amorphous alumina used in Examples 1 to 3 are preferable because they give a heat-sensitive adhesive sheet superior to other oil-absorbing pigments. Examples 5 and 6 are examples in which oil-absorbing pigments having an average particle size of more than 15 μm are used.
The adhesive function is lower than that of μm or less. When a tackifier is used together as in Example 7, the blocking resistance is slightly inferior, but the lowered adhesive function can be improved. The adhesive function and blocking resistance can be balanced by appropriately combining the oil-absorbing pigment and the tackifier used.

Example 9 is an example in which 45 parts by weight of the oil absorbing pigment is used, and Example 10 is an example in which 1 part of the oil absorbing pigment is used. In the case of Example 9, there is a tendency that the adhesion function is slightly deteriorated, and in the case of Example 10, there is a tendency that the blocking resistance and the printability are slightly deteriorated.
It is understood that the amount of the oil absorbing pigment used is preferably 2 to 20 parts by weight with respect to 100 parts by weight of the solid plasticizer. Example 11 is an example of making and using another adhesive composition,
Examples 12 to 14 are pressure-sensitive adhesive compositions obtained by adding an oil-absorbing pigment to a commercially available pressure-sensitive adhesive composition and examples of use.
It turns out that all are excellent.

[0066]

As described above, the heat-sensitive adhesive of the present invention is
The heat-sensitive adhesive was capable of producing a heat-sensitive adhesive sheet having excellent adhesive function, blocking resistance, and printability. Further, the heat-sensitive adhesive sheet of the present invention was a heat-sensitive adhesive sheet having excellent adhesive function, blocking resistance, and printability.

Claims (6)

[Claims] 1. An oil absorption (based on JIS-K-5101) of 10 in a heat-sensitive adhesive mainly composed of a thermoplastic resin and a solid plasticizer.
A heat-sensitive pressure-sensitive adhesive, characterized in that an oil-absorbing pigment of 0 ml / 100 g or more is contained in an amount of 0.5 to 50 solid parts by weight based on 100 parts by weight of a solid plasticizer. 2. The dispersed particles of the oil-absorbing pigment contained in the heat-sensitive adhesive have an average particle diameter of 15 μm or less.
The heat-sensitive adhesive described. 3. A solid plasticizer having a content of oil-absorbing pigment of 100
The heat-sensitive adhesive according to claim 1 or 2, which is 2 to 20 solid parts by weight with respect to the solid parts by weight. 4. The heat-sensitive adhesive according to claim 1, wherein the oil absorbing pigment is at least one selected from calcined kaolin, amorphous silica, and amorphous alumina. . 5. The method according to claim 1 on at least one surface of the substrate.
Applying the heat-sensitive adhesive according to claim 4,
A heat-sensitive adhesive sheet obtained by drying. 6. The heat-sensitive adhesive sheet according to claim 5, wherein the surface coated with the heat-sensitive adhesive is dried and printed.