TW202106838A - Temperature-sensitive adhesive - Google Patents

Abstract

A temperature-sensitive adhesive of the present invention contains a side-chain crystalline polymer, and its adhesive strength decreases at a temperature lower than the melting point of the side-chain crystalline polymer, and the temperature-sensitive adhesive further contains a tackifier having an acid value of 20 mgKOH/g or more. The content of the tackifier may be 10 to 50 parts by weight with respect to 100 parts by weight of the side-chain crystalline polymer. Further, the 180° peel strength with respect to the cycloolefin polymer film at 50℃ may be 1.0 N/ 25 mm or more.

Description

Temperature Sensitive Adhesive

The present invention relates to a temperature-sensitive adhesive.

The temperature-sensitive adhesive contains a side chain crystalline polymer as the main component, and if it is cooled to a temperature below the melting point of the side chain crystalline polymer, the adhesive force will decrease due to the crystallization of the side chain crystalline polymer. The temperature-sensitive adhesive is processed into sheets, tapes, etc., and is used when temporarily fixing a substrate made of glass, plastic, etc., in the manufacturing steps of flat-panel displays (hereinafter, sometimes referred to as "FPD"). Use (for example, refer to Patent Document 1). The temperature-sensitive adhesive used in this type is sometimes heated to a high temperature in different steps, so heat resistance such as the suppression of the floating of the adherend is required. In addition, peelability after being heated to a high temperature is also required.

However, when the conventional temperature-sensitive adhesive is heated to a high temperature, it may float due to the relationship between the adherend. This tendency occurs when the cyclic olefin polymer film (hereinafter, sometimes referred to as "COP film") is easily deformed when heated to 130°C or higher, and the stress during deformation tends to become greater than the adhesive force. obvious. If the temperature-sensitive adhesive is annealed at 200°C for about 30 minutes, the adhesion to the adherend can be improved and the floating of the adherend can be suppressed, but it takes one more step.

[Prior Technical Literature]

[Patent Literature]

[Patent Document 1] JP 2012-102212 A

The subject of the present invention is to provide a temperature-sensitive adhesive that can suppress the occurrence of floating of the adherend when heated to a high temperature, and has excellent peelability after being heated to a high temperature.

The temperature sensitive adhesive of the present invention contains a side chain crystalline polymer, and the adhesive force will be lowered at a temperature below the melting point of the aforementioned side chain crystalline polymer. The temperature sensitive adhesive further contains a side chain crystalline polymer with a concentration of 20 mgKOH/g or more. The acid value of the tackifier.

According to the present invention, there are the following effects: when heated to a high temperature, the occurrence of floating of the adherend can be suppressed, and the peelability after being heated to a high temperature is also excellent.

<Temperature Sensitive Adhesive>

Hereinafter, the temperature-sensitive adhesive related to one embodiment of the present invention will be described in detail.

(Side chain crystalline polymer)

The temperature-sensitive adhesive of this embodiment contains a side chain crystalline polymer. The side chain crystalline polymer is a polymer with a melting point. The so-called melting point means that through a certain equilibrium process, the original is integrated into order The temperature at which a specific part of the aligned polymer becomes a disordered state, and is a value obtained by measuring using a differential scanning calorimeter (DSC) under a measurement condition of 10°C/min.

The side chain crystalline polymer crystallizes at a temperature below the melting point, and undergoes phase transition at a temperature above the melting point to show fluidity. That is, the side chain crystalline polymer has temperature sensitivity that reversibly generates the crystalline state and the fluid state in response to temperature changes.

The adhesive force of the temperature-sensitive adhesive of this embodiment will decrease at a temperature below the melting point of the side chain crystalline polymer. In other words, the temperature-sensitive adhesive of this embodiment contains a side-chain crystalline polymer at a ratio at which the adhesive force of the side-chain crystalline polymer will decrease when it crystallizes at a temperature below the melting point. That is, the temperature-sensitive adhesive of this embodiment contains a side chain crystalline polymer as a main component. Therefore, when peeling the adherend from the temperature-sensitive adhesive, if the temperature-sensitive adhesive is cooled to a temperature below the melting point of the side-chain crystalline polymer, the temperature will decrease due to the crystallization of the side-chain crystalline polymer. Adhesion. In addition, if the temperature-sensitive adhesive is heated to a temperature above the melting point of the side chain crystalline polymer, the side chain crystalline polymer exhibits fluidity and the adhesive force is restored, so it can be used repeatedly. In addition, the above-mentioned so-called main component is the most contained component in terms of weight ratio in the temperature-sensitive adhesive.

The side chain crystalline polymer system contains a (meth)acrylate having a linear alkyl group having 16 or more carbon atoms as a monomer component. In the (meth)acrylate having a linear alkyl group with a carbon number of 16 or more, the linear alkyl group with a carbon number of 16 or more functions as a side chain crystalline part in a side chain crystalline polymer. That is, the side chain crystalline polymer is a comb-shaped polymer having a linear alkyl group with a carbon number of 16 or more in the side chain, and the side chain is integrated into an orderly arrangement by intermolecular force or the like for crystallization.化. In addition, the aforementioned (meth)acrylate refers to acrylate or methacrylate.

The (meth)acrylates having a linear alkyl group with 16 or more carbon atoms include, for example, cetyl (meth)acrylate, stearyl (meth)acrylate, eicosyl (meth)acrylate, (Methyl) Propane (Meth)acrylates having linear alkyl groups with 16 to 22 carbon atoms, such as behenate behenate. The exemplified (meth)acrylate type may be used alone or in combination of two or more types. The content of the (meth)acrylate having a linear alkyl group with 16 or more carbon atoms is preferably 10 to 99% by weight in the monomer components constituting the side chain crystalline polymer, and more preferably 20 to The ratio of 99% by weight.

The monomer component constituting the side chain crystalline polymer may contain other monomers that can be copolymerized with (meth)acrylate having a linear alkyl group having 16 or more carbon atoms. Examples of other single systems include (meth)acrylates and polar monomers having an alkyl group having 1 to 6 carbon atoms.

The (meth)acrylates having an alkyl group having 1 to 6 carbon atoms include, for example, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and hexyl (meth)acrylate. Ester etc. Only 1 type may be used for the (meth)acrylate type illustrated, and 2 or more types may be used together. The content of the (meth)acrylate having a linear alkyl group having 1 to 6 carbon atoms is preferably 70% by weight or less in the monomer components constituting the side chain crystalline polymer, and more preferably 1 to The ratio of 70% by weight.

Examples of polar monosystems include: acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, and other ethylenically unsaturated monomers having carboxyl groups; 2-hydroxyethyl (meth)acrylic acid Ethylene unsaturated monomers having hydroxyl groups such as esters, 2-hydroxypropyl (meth)acrylate, 2-hydroxyhexyl (meth)acrylate, and the like. Only one type of the exemplified polar monosystem may be used, or two or more types may be used in combination. The content of the polar monomer is preferably a ratio of 10% by weight or less in the monomer components constituting the side chain crystalline polymer, and more preferably a ratio of 1 to 10% by weight.

The monomer components constituting the side chain crystalline polymer may further contain a reactive fluorine compound. In this way, if the temperature-sensitive adhesive is cooled to a temperature below the melting point of the side chain crystalline polymer, in addition to the decrease in the adhesive force due to the crystallization of the side chain crystalline polymer, it will also be applied The releasability of fluorine compounds can greatly reduce the adhesion.

The so-called reactive fluorine compound refers to a fluorine compound having a functional group showing reactivity. Examples of functional groups showing reactivity include epoxy groups (including glycidyl groups and epoxy cycloalkyl groups), mercapto groups, methanol groups (hydroxymethyl), carboxyl groups, silanol groups, phenol groups, amino groups, and hydroxyl groups. , Groups with ethylenically unsaturated double bonds, etc. Examples of the group having an ethylenically unsaturated double bond include a vinyl group, an allyl group, a (meth)acryl group, a (meth)acryloyl group, and a (meth)acryloyloxy group.

Specific examples of the reactive fluorine compound include compounds represented by the following general formula (I) and the like.

R ₁ -CF ₃ (I) [In the formula, R ₁ represents a group: CH ₂ =CHCOOR ² -or CH ₂ =C(CH ₃ )COOR ^2- (In the formula, R ² represents an alkylene group)]

The ^{alkylene group represented by R 2} includes, for example, methylene, ethylene, trimethylene, propylene, tetramethylene, pentamethylene, hexamethylene, etc., straight with carbon numbers from 1 to 6 Chain or branched alkylene, etc.

Specific examples of the compound represented by the general formula (I) include 2,2,2-trifluoroethyl acrylate represented by the following formula (Ia), and 2,2 methacrylic acid represented by the formula (Ib) , 2-Trifluoroethyl ester and so on.

Commercial products can be used for the above-mentioned reactive fluorine compound. Examples of commercially available reactive fluorine compounds include: "VISCOAT 3F" and "VISCOAT" manufactured by Osaka Organic Chemical Industry Co., Ltd. 3FM", "VISCOAT 4F", "VISCOAT 8F", "VISCOAT 8FM", "Lightester M-3F" of Kyoeisha Chemical Company, etc.

The reactive fluorine compound system may use only 1 type, and may use 2 or more types together. The content of the reactive fluorine compound in the monomer component is preferably 1 to 20% by weight, more preferably 1 to 10% by weight.

The preferred composition of the side chain crystalline polymer is a (meth)acrylate having a linear alkyl group with a carbon number of 16 or more, 25 to 30% by weight, and a (meth)acrylate having an alkyl group with a carbon number of 1 to 6 ) 50 to 65% by weight of acrylate, 5 to 10% by weight of polar monomer, and 5 to 10% by weight of reactive fluorine compound.

The polymerization method of the monomer components includes, for example, a solution polymerization method, a bulk polymerization method, a suspension polymerization method, and an emulsion polymerization method. When using the solution polymerization method, it is only necessary to mix the monomer components and the solvent, add polymerization initiators, chain transfer agents, etc. as needed, and react at 40 to 90°C for about 2 to 10 hours while stirring.

The weight average molecular weight of the side chain crystalline polymer is preferably 100,000 or more, more preferably 300,000 to 900,000, and still more preferably 400,000 to 700,000. The weight average molecular weight is measured by Gel Permeation Chromatography (GPC), and the measured value obtained is converted into polystyrene.

The melting point of the side chain crystalline polymer is preferably 0°C or higher, more preferably 10 to 60°C. The melting point can be adjusted, for example, by changing the composition of monomer components constituting the side chain crystalline polymer.

(Tackifier)

In addition to the above-mentioned side chain crystalline polymer, the temperature-sensitive adhesive of this embodiment also contains a tackifier having an acid value of 20 mgKOH/g or more. As a result, for COP films, which are easily deformed when heated to 130°C or higher, and the stress during deformation is likely to become greater than the adhesive force, it is possible to obtain It can suppress the floating or peeling of the adherend when heated to a high temperature, and the peelability after being heated to a high temperature is also excellent. Therefore, if the temperature-sensitive adhesive of this embodiment is used in the manufacturing process of a product containing a substrate such as a COP film, it does not need to consume annealing treatment, etc., and the process can be performed smoothly with good yield. If a specific example is given, the temperature-sensitive adhesive system of this embodiment can be suitably used for temporary fixing of the substrate in the manufacturing step of the FPD. In addition, it is speculated that the above-mentioned thickening agent has the effect of increasing the affinity of the temperature-sensitive adhesive and improving the adhesion to the substrate such as the COP film.

In addition, according to the temperature-sensitive adhesive of this embodiment, for other substrates other than the COP film, it can be heated to a high temperature to suppress the floating or peeling of the substrate, and be heated It also has excellent peelability after high temperature. Therefore, the temperature-sensitive adhesive system of this embodiment can also exhibit high versatility. Examples of other substrates to be bonded include polyimide film, polyethylene terephthalate film, polyvinyl butyral film, stainless steel (SUS), glass, and the like.

The upper limit of the acid value is not particularly limited, but may be 300 mgKOH/g or less. The acid value is preferably 100 to 300 mgKOH/g, more preferably 110 to 255 mgKOH/g. The acid value is the value measured in accordance with JIS K 2501.

The content of the tackifier is relative to 100 parts by weight of the side chain crystalline polymer, preferably 10 to 50 parts by weight, more preferably 10 to 30 parts by weight.

The tackifier system may be a rosin resin. In addition, the softening point of the tackifier is preferably 90 to 175°C. The softening point is a value measured in accordance with the Ring and Ball method specified in JIS K 5902.

Commercial products can be used for the above-mentioned tackifiers. Examples of commercially available tackifier systems include "KE-604", "KR-140", and "R-95" manufactured by Arakawa Chemical Industry Co., Ltd.

In addition, only one type of thickener system may be used, or two or more types may be used in combination. When two or more are used in combination, as long as the mixture has an acid value of 20mgKOH/g or more, it can be used in combination with less than 20mgKOH/g. The acid value of the tackifier. For example, the tackifier may be a mixture of a first tackifier and a second tackifier with different acid values. In this way, the degree of freedom of acid value adjustment can be improved. The acid value of one of the first thickener and the second thickener may be less than 20 mgKOH/g.

The 180° peel strength of the temperature-sensitive adhesive to the COP film at 50°C is preferably 1.0N/25mm or more, more preferably 2.0N/25mm or more, and still more preferably 2.5N/25mm or more. As a result, the temperature-sensitive adhesive has excellent adhesion to the COP film. The upper limit of the 180° peel strength of the COP film at 50°C is not particularly limited, but may be 7.0 N/25 mm or less. The 180° peel strength is the value measured in accordance with JIS Z0237.

The 180° peel strength of the temperature-sensitive adhesive to the COP film at 5°C after 130°C is preferably 0.2N/25mm or less. Thereby, after the temperature-sensitive adhesive is heated to a high temperature, it also has excellent peelability for the COP film. In addition, the lower limit of the 180° peel strength of the COP film at 5°C after 130°C is not particularly limited, but it may be 0.05N/25mm or more.

(Crosslinking agent)

The temperature-sensitive adhesive system may further contain a cross-linking agent. Examples of the crosslinking agent system include metal chelate compounds, Aziridine compounds, isocyanate compounds, and epoxy compounds.

If a metal chelate compound is used as a cross-linking agent, the heat resistance of the temperature-sensitive adhesive can be improved. The metal chelate compound system includes, for example, an acetoxypropyl copper coordination compound of a polyvalent metal, and an acetacetate coordination compound of a polyvalent metal. Examples of the polyvalent metal system include aluminum, nickel, chromium, iron, titanium, zinc, cobalt, manganese, and zirconium. The metal chelate compound system may use only 1 type, and may use 2 or more types together. Among these, the acetoxypropyl copper coordination compound or the acetoxyacetate coordination compound of aluminum is preferable, and the aluminum acetoxyacetate is more preferable.

The crosslinking conditions are that the heating temperature is about 90 to 120°C, and the heating time is about 1 minute to 20 minutes.

The content of the crosslinking agent is relative to 100 parts by weight of the side chain crystalline polymer, preferably 0.1 to 10 parts by weight.

(Crosslinking delay agent)

The temperature-sensitive adhesive system may further contain a crosslinking retarder. Thereby, the crosslinking reaction by the crosslinking agent is delayed and the viscosity is prevented from increasing in a short time, and the usable time can be increased. The addition of the crosslinking retarder is preferably carried out before the addition of the crosslinking agent. The content of the crosslinking retarder can be the same as the content of the crosslinking agent. The crosslinking retarder system includes, for example, acetoxypropyl copper and the like, but it is not limited to this.

The use form of the above-mentioned temperature-sensitive adhesive is not particularly limited. For example, it can be used as it is, or it can be used in the form of an adhesive sheet, adhesive tape, etc. as described below.

<Temperature Adhesive Sheet>

The temperature-sensitive adhesive sheet of this embodiment includes the above-mentioned temperature-sensitive adhesive and is in the form of a substrate without a substrate. The thickness of the temperature-sensitive adhesive sheet is preferably 5 to 100 μm, more preferably 5 to 50 μm.

A release film can be laminated on the surface of the temperature sensitive adhesive sheet. For example, the release film may be coated with a release agent such as silicone on the surface of a film composed of polyethylene terephthalate (hereinafter, sometimes referred to as "PET"). The thickness of the release film is preferably 5 to 500 μm, more preferably 25 to 250 μm. The release film is peeled off when the temperature-sensitive adhesive sheet is used.

<Temperature Adhesive Tape>

The temperature-sensitive adhesive tape of this embodiment is provided with a film-like substrate and an adhesive layer laminated on at least one side of the substrate. The so-called film-like system is not limited to the film-like, as long as the effect of this embodiment is not impaired, it also includes the concept of film-like to sheet-like.

The constituent materials of the base material include, for example, polyethylene, polyethylene terephthalate, polypropylene, polyester, polyamide, polyimide, polycarbonate, ethylene vinyl acetate copolymer, ethylene ethyl Synthetic resins such as acrylate copolymer, ethylene polypropylene copolymer, and polyvinyl chloride.

The structure of the substrate may be either a single-layer structure or a multilayer structure. The thickness of the substrate is preferably 5 to 500 μm, more preferably 25 to 250 μm. To improve the adhesion to the adhesive layer, surface treatment can be applied to the substrate. Examples of the surface treatment system include corona discharge treatment, plasma treatment, sandblasting treatment, chemical etching treatment, and primer treatment.

The adhesive layer laminated on at least one side of the substrate contains the above-mentioned temperature-sensitive adhesive. When laminating the adhesive on at least one side of the substrate, for example, add a solvent to the temperature-sensitive adhesive to prepare a coating liquid, and apply the resulting coating liquid on one side of the substrate with a coater, etc. Or dry it on both sides. Examples of the coating machine system include a knife coater, a roll coater, a calender coater, a corner wheel coater, a gravure coater, and a bar coater.

The thickness of the adhesive layer is preferably 5 to 100 μm, more preferably 5 to 50 μm.

When the adhesive layer is layered on two areas of the substrate, the thickness and composition of the adhesive layer on one side and the adhesive layer on the other side may be the same or different. In addition, as long as the adhesive layer on one side contains the above-mentioned temperature-sensitive adhesive, the adhesive layer on the other side is not particularly limited. The adhesive layer on the other side may be composed of, for example, a natural rubber adhesive, a synthetic rubber adhesive, an acrylic adhesive, a silicone adhesive, a urethane adhesive, or the like.

A release film can be laminated on the surface of the temperature-sensitive adhesive tape. Examples of the release film system are the same as those exemplified by the above-mentioned temperature-sensitive adhesive sheet. The release film is peeled off when the temperature-sensitive adhesive tape is used.

Hereinafter, the present invention will be explained in detail with reference to synthesis examples and examples, but the present invention is not limited to only the following synthesis examples and examples.

(Synthesis example: side chain crystalline polymer)

First, the monomers shown in Table 1 were added to the reaction vessel at the ratio shown in Table 1. The single system shown in Table 1 is as follows.

C18A: Stearyl Acrylate

C1A: Methyl acrylate

V-3F: 2,2,2-trifluoroethyl acrylate represented by the above formula (Ia), a reactive fluorine compound manufactured by Osaka Organic Chemical Industry Co., Ltd. "VISCOAT 3F"

AA: Acrylic

Next, a mixed solvent of ethyl acetate:toluene=75:25 (weight ratio) was added to the reaction vessel so that the solid content concentration became 30% by weight to obtain a mixed liquid. The obtained mixed liquid was stirred at 55°C for 4 hours to copolymerize each monomer to obtain a side chain crystalline polymer.

Table 1 shows the weight average molecular weight and melting point of the obtained side chain crystalline polymer. The weight average molecular weight is a value obtained by GPC measurement in terms of polystyrene conversion. The melting point is a value measured using DSC under a measurement condition of 10°C/min.

[Table 1]

1) C18A: Stearyl acrylate, C1A: Methyl acrylate, V-3F: 2,2,2-Trifluoroethyl acrylate, AA: Acrylic acid

[Examples 1 to 9 and Comparative Examples 1 to 7]

<Production of Temperature Sensitive Adhesive Sheet>

First, with respect to 100 parts by weight of the side chain crystalline polymer obtained in the synthesis example, the thickener shown in Table 2 was mixed at a ratio of 20 parts by weight. The tackifier systems shown in Table 2 are as follows.

A: Arakawa Chemical Industry Co., Ltd. rosin ester "D-160" with an acid value of 10 to 16 mgKOH/g and a softening point of 150 to 170°C

B: Special rosin ester "A-100" manufactured by Arakawa Chemical Industry Co., Ltd. with an acid value of 2 to 10 mgKOH/g and a softening point of 95 to 105°C

C: Acid-modified ultra-light rosin made by Arakawa Chemical Industry Co., Ltd. with an acid value of 230 to 245 mgKOH/g and a softening point of 124 to 134°C "KE-604"

D: An ultra-light polymer rosin made by Arakawa Chemical Industry Co., Ltd. with an acid value of 130 to 160 mgKOH/g and a softening point of 130 to 150°C "KR-140"

E: Polymerized rosin "R-95" manufactured by Arakawa Chemical Industry Co., Ltd. with an acid value of 158 to 168 mgKOH/g and a softening point of 93 to 103°C

F: A mixture of A and C (mixing ratio by weight 50:50)

Then, after mixing the crosslinking retarder at a ratio of 3 parts by weight with respect to 100 parts by weight of the side chain crystalline polymer, the crosslinking agent was further mixed at a ratio of 3 parts by weight to obtain a temperature-sensitive adhesive. The crosslinking retarder and crosslinking agent used are as follows.

Crosslinking retarder: Acetylacetone

Crosslinking agent: As a metal chelate compound, Kawaken Fine Chemical Co., Ltd.'s ginsenoside aluminum acetone

Next, the obtained temperature-sensitive adhesive was adjusted to a solid content concentration of 23% by weight with ethyl acetate to obtain a coating liquid. Then, the obtained coating liquid was coated on the release film, and the cross-linking reaction was performed under the conditions of 110° C.×3 minutes to obtain a temperature-sensitive adhesive sheet with a thickness of 25 μm. In addition, as the release film, a polyethylene terephthalate film with a thickness of 50 μm coated with silicone on the surface was used.

<evaluation>

For each of the temperature-sensitive adhesive sheets obtained in Examples 1 to 9 and Comparative Examples 1 to 7, the 180° peel strength and the high temperature heating test were evaluated. The evaluation methods are shown below, and the results are shown in Table 2.

(180° peel strength)

[Examples 1 to 3, 5, 7 to 9 and Comparative Examples 1 to 3, 5, 7]

Measure the 180° peel strength at 50°C and 5°C according to JIS Z0237. Specifically, first, at an ambient temperature of 50° C., a 2 kg rubber roller was used to affix one side of the temperature-sensitive adhesive sheet to the glass plate.

Next, at the ambient temperature, the substrate shown in Table 2 was attached to the other side of the temperature-sensitive adhesive sheet to obtain a test piece. The adherends shown in Table 2 are as follows.

COP: COP film "ZEONOR film" made by Japan's ZEON company with a thickness of 42μm

PI: Polyimide film "KAPTON 100H" made by TORAY DUPONT with a thickness of 25μm

PET: PET film "S-25" made by UNITIKA with a thickness of 25μm

PVB: PVB film made by coating the polyvinyl butyral "BL-S" made by Sekisui Chemical Industry Co., Ltd. on one side of a substrate made of PET with a thickness of 100μm and a thickness of 10μm.

After setting the obtained test piece under the following conditions, the adherend was peeled 180° from the temperature-sensitive adhesive sheet at a speed of 300 mm/min using a load cell (n=3).

[50°C]

The test piece was allowed to stand at an ambient temperature of 50°C for 20 minutes and then peeled at 180°.

[5°C]

After heating the test piece in a hot air circulation oven at 130°C for 90 minutes, it was placed on a cooling plate at 5°C for 20 minutes and then peeled at 180°.

[Examples 4 and 6 and Comparative Examples 4 and 6]

First, at an ambient temperature of 50°C, one side of the temperature-sensitive adhesive sheet is attached to a PET film with a thickness of 100μm. Then, at the ambient temperature, the substrate shown in Table 2 was attached to the other side of the temperature-sensitive adhesive sheet to obtain a test piece. The adherends shown in Table 2 are as follows.

SUS: SUS304 with a thickness of 1mm

Glass: "EAGLE XG" made by Corning with a thickness of 0.7mm

Next, except for 180° peeling of the PET film from the temperature-sensitive adhesive sheet, the 180° peel strength at 50°C and 5°C was measured in the same manner as in Examples 1 to 3, 5, and 7 to 9.

(High temperature heating test)

First, the test piece was obtained in the same manner as the evaluation of the 180° peel strength described above. Next, the obtained test piece was allowed to stand at 50°C for 3 minutes, and then heated in a hot air circulating oven at 130°C for 90 minutes. Next, by visually observing the state of the test piece at room temperature (23° C.), it is evaluated whether or not there is floating of the adherend. The evaluation standard system is set as follows.

○: No floating is seen in the adherend.

×: Floating is seen in the adherend.

[Table 2]

It is obvious from Table 2 that Examples 1 to 9 have a high value of 180° peel strength at 50°C, and a low value of 180° peel strength at 5°C after 130°C. In addition, it can be seen that Examples 1 to 9 can suppress the occurrence of floating of the adherend when heated to 130°C.

Claims (7)

A temperature-sensitive adhesive containing side-chain crystalline polymer, and the adhesive force will decrease at a temperature below the melting point of the aforementioned side-chain crystalline polymer. The temperature-sensitive adhesive further contains a tackifier with an acid value of 20 mgKOH/g or more. The temperature-sensitive adhesive according to claim 1, wherein the content of the tackifier is 10 to 50 parts by weight relative to 100 parts by weight of the side chain crystalline polymer. The temperature-sensitive adhesive according to claim 1 or 2, wherein the tackifier is a rosin resin. The temperature-sensitive adhesive according to any one of claims 1 to 3, wherein the softening point of the aforementioned thickener is 90 to 175°C. The temperature-sensitive adhesive according to any one of claims 1 to 4, which has a 180° peel strength of a cycloolefin polymer film at 50°C of 1.0 N/25 mm or more. A temperature-sensitive adhesive sheet comprising the temperature-sensitive adhesive described in any one of claims 1 to 5. A temperature-sensitive adhesive tape with: Film-like substrate, and An adhesive layer laminated on at least one side of the aforementioned substrate and containing the temperature-sensitive adhesive described in any one of claims 1 to 5.