JP5639438B2 - Temperature sensitive adhesive - Google Patents

Description

  The present invention relates to a temperature-sensitive adhesive whose adhesive strength decreases at a predetermined temperature.

  A temperature-sensitive adhesive is an adhesive whose adhesive force can be reversibly controlled by heat (see, for example, Patent Document 1). More specifically, the temperature-sensitive adhesive contains a side chain crystalline polymer as a main component, and when the side chain crystalline polymer is cooled to a temperature below the melting point of the side chain crystalline polymer, the side chain crystalline polymer is The adhesive strength is reduced by crystallization.

  However, the conventional temperature-sensitive adhesive as described in Patent Document 1 is exposed to a high temperature (for example, 100 ° C. or more) in a state where the adherend is stuck and fixed, even if it is cooled to a predetermined temperature. There was a problem that it was difficult for the adhesive force to decrease and it was difficult to peel off.

JP-A-9-251923

  The subject of this invention is providing the temperature sensitive adhesive which is easy to peel even when it is a case where it exposes to high temperature.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found a solution means having the following constitution and have completed the present invention.
(1) A temperature-sensitive pressure-sensitive adhesive containing a side-chain crystalline polymer and having reduced adhesive strength at a temperature lower than the melting point of the side-chain crystalline polymer, wherein the side-chain crystalline polymer is an ultraviolet curable functional group. A temperature-sensitive adhesive, which is an ultraviolet curable side-chain crystalline polymer having a group.
(2) The temperature-sensitive adhesive according to (1), wherein the ultraviolet curable side chain crystalline polymer is obtained by reacting a side chain crystalline polymer with a compound having an ultraviolet curable functional group.
(3) The temperature-sensitive adhesive according to (1) or (2), wherein the ultraviolet curable functional group is a (meth) acryloyloxy group.
(4) The temperature-sensitive property according to any one of (1) to (3), wherein the ultraviolet curable side-chain crystalline polymer is crystallized at a temperature lower than the melting point and exhibits fluidity at a temperature higher than the melting point. Adhesive.
(5) The temperature-sensitive adhesive according to any one of (1) to (4), wherein the adhered adherend is exposed to a temperature of 100 ° C. or higher and then removed at a temperature lower than the melting point.
(6) A temperature-sensitive adhesive sheet comprising the temperature-sensitive adhesive according to any one of (1) to (5).
(7) A temperature-sensitive adhesive tape, wherein an adhesive layer comprising the temperature-sensitive adhesive according to any one of (1) to (5) is provided on one side or both sides of a base film.
The “sheet” in the present invention is not limited to a sheet shape, and is a concept including a sheet shape or a film shape as long as the effects of the present invention are not impaired.

  According to the present invention, since the side chain crystalline polymer has an ultraviolet curable functional group, it is cured when irradiated with ultraviolet rays, and the adhesive strength is reduced. Therefore, when peeling from the adherend, in addition to a decrease in adhesive strength due to crystallization of the side chain crystalline polymer, a decrease in adhesive strength due to UV curing is also added. Even if it exists, adhesive force can fully be reduced and peeling can be performed easily. Moreover, since it utilizes the phase change of the side chain crystalline polymer, it can be used repeatedly.

  The pressure-sensitive adhesive according to the present invention is a temperature-sensitive pressure-sensitive adhesive. The temperature-sensitive pressure-sensitive adhesive means a pressure-sensitive adhesive whose adhesive force changes in response to a temperature change. Hereinafter, an embodiment of the temperature-sensitive adhesive according to the present invention will be described.

  The temperature-sensitive adhesive according to this embodiment contains a side chain crystalline polymer. The side-chain crystalline polymer is crystallized at a temperature lower than the melting point, and exhibits a fluidity by phase transition at a temperature higher than the melting point. That is, the side chain crystalline polymer reversibly causes a crystalline state and a fluid state in response to a temperature change.

  The temperature-sensitive adhesive according to this embodiment contains the side-chain crystalline polymer in such a ratio that the adhesive strength is exhibited when the side-chain crystalline polymer exhibits fluidity at a temperature equal to or higher than the melting point. Thus, when sticking and fixing the adherend, if the temperature-sensitive adhesive is heated to a temperature equal to or higher than the melting point of the side-chain crystalline polymer, the side-chain crystalline polymer exhibits fluidity, thereby causing adhesive strength. Is expressed. Further, when peeling from the adherend, if the temperature-sensitive adhesive is cooled to a temperature lower than the melting point of the side-chain crystalline polymer, the side-chain crystalline polymer is crystallized to reduce the adhesive strength.

  Here, the side chain crystalline polymer according to the present embodiment has an ultraviolet curable functional group. The ultraviolet curable functional group means a functional group that is cured by ultraviolet irradiation. Therefore, when the temperature-sensitive adhesive according to the present embodiment is peeled off from the adherend, in addition to the decrease in adhesive force due to the crystallization of the side-chain crystalline polymer described above, the adhesive caused by ultraviolet curing. Since a reduction in force is also added, for example, even when exposed to a high temperature of 100 ° C. or higher, preferably 150 ° C. or higher, more preferably 180 to 220 ° C., the adhesive strength is sufficiently reduced to facilitate peeling. Can do.

  A side chain crystalline polymer having an ultraviolet curable functional group, that is, an ultraviolet curable side chain crystalline polymer is obtained by reacting a side chain crystalline polymer with a compound having an ultraviolet curable functional group. Specifically, the side-chain crystalline polymer includes, for example, a (meth) acrylate having a linear alkyl group having 16 or more carbon atoms, a (meth) acrylate having an alkyl group having 1 to 6 carbon atoms, and hydroxy It consists of a copolymer obtained by polymerizing (meth) acrylate having an alkyl group.

  Examples of the (meth) acrylate having a linear alkyl group having 16 or more carbon atoms include 16 to 16 carbon atoms such as cetyl (meth) acrylate, stearyl (meth) acrylate, eicosyl (meth) acrylate, and behenyl (meth) acrylate. (Meth) acrylate having 22 linear alkyl groups can be mentioned. Examples of the (meth) acrylate having 1 to 6 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) ) Acrylate, hexyl (meth) acrylate and the like, and these may be used alone or in combination of two or more.

  The (meth) acrylate having a hydroxyalkyl group reacts with a compound having an ultraviolet curable functional group, which will be described later. For example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2- Examples thereof include hydroxyhexyl (meth) acrylate, and these may be used alone or in combination of two or more.

  The polymerization rate of the side chain crystalline polymer is, for example, 20 to 99 parts by weight of the (meth) acrylate having a linear alkyl group having 16 or more carbon atoms and (meth) acrylate having an alkyl group having 1 to 6 carbon atoms. Is preferably 0 to 70 parts by weight and (meth) acrylate having a hydroxyalkyl group is 1 to 20 parts by weight.

  The polymerization method is not particularly limited, and for example, a solution polymerization method, a bulk polymerization method, a suspension polymerization method, an emulsion polymerization method and the like can be employed. For example, when the solution polymerization method is employed, the monomer can be polymerized by mixing the monomer exemplified above in a solvent and stirring at about 40 to 90 ° C. for about 2 to 10 hours.

  The weight average molecular weight of the side chain crystalline polymer is preferably 100,000 or more, more preferably 400,000 to 800,000. If the weight average molecular weight is too small, when the temperature-sensitive adhesive is peeled off from the adherend, there is a possibility that so-called adhesive residue that the adhesive remains on the adherend increases. Moreover, when the said weight average molecular weight is too large, there exists a possibility that the reactivity with the compound which has an ultraviolet curable functional group may fall. The weight average molecular weight is a value obtained by measuring a side chain crystalline polymer by gel permeation chromatography (GPC) and converting the obtained measurement value to polystyrene.

  The melting point of the side-chain crystalline polymer means a temperature at which a specific portion of the polymer that is initially aligned in an ordered arrangement becomes disordered by a certain equilibrium process. A differential thermal scanning calorimeter (DSC) ) By the measurement conditions at 10 ° C./min. As said melting | fusing point, 0 degreeC or more is preferable and 10-60 degreeC is more preferable. The melting point can be arbitrarily set to a predetermined value by changing the composition of the side chain crystalline polymer.

  On the other hand, in the compound having the ultraviolet curable functional group, examples of the ultraviolet curable functional group include a (meth) acryloyloxy group and a vinyl group, and a (meth) acryloyloxy group is preferable.

  As the compound having an ultraviolet curable functional group, an isocyanate compound is preferable in reacting with the (meth) acrylate having a hydroxyalkyl group of the side chain crystalline polymer. Examples of the isocyanate compound include 2-methacryloyloxyethyl isocyanate represented by the following formula (I), 2-acryloyloxyethyl isocyanate represented by the following formula (II), and the following formula (III). 1,1-bis (acryloyloxymethyl) ethyl isocyanate and the like are preferable, and 2-acryloyloxyethyl isocyanate represented by the following formula (II) is particularly preferable.

  Examples of other isocyanate compounds other than the isocyanate compounds represented by the formulas (I) to (III) include 2- (meth) acryloyloxypropyl isocyanate, 2- (meth) acryloyloxybutyl isocyanate, ( And (meth) acryloyl isocyanate, 1- (4-vinylphenyl) -1-methylethyl isocyanate, and the like. These exemplified isocyanate compounds may be used alone or as a mixture.

  The reaction between the side chain crystalline polymer and the compound having an ultraviolet curable functional group is performed by mixing the side chain crystalline polymer and the compound at a predetermined ratio, and then in an inert gas atmosphere such as nitrogen gas, in an amount of 40-80. It is preferable to stir at about 1 ° C. for about 1 to 6 hours.

  The mixing ratio of the side chain crystalline polymer and the compound having an ultraviolet curable functional group is, for example, a ratio of 1 to 180 parts by weight of the compound having an ultraviolet curable functional group with respect to 100 parts by weight of the side chain crystalline polymer. The ratio is preferably 10 to 50 parts by weight. If the ratio of the side chain crystalline polymer is too small or the ratio of the compound is too large, the adhesive force is hardly lowered even when the temperature-sensitive adhesive is cooled to a predetermined temperature. Further, when the proportion of the side chain crystalline polymer is too large or the proportion of the compound is too small, it becomes difficult to cure even when irradiated with ultraviolet rays.

  A photopolymerization initiator is used for curing the ultraviolet curable functional group. The photopolymerization initiator may be appropriately selected according to the composition of the ultraviolet curable functional group, and is not particularly limited. Moreover, the said photoinitiator can use a commercial item. Examples of commercially available photopolymerization initiators include “IRGACURE 184” and “IRGACURE 500” manufactured by Ciba Japan.

  As a weight average molecular weight of the ultraviolet curable side chain crystalline polymer obtained, 100,000 or more are preferable and 400,000-800,000 are more preferable. If the weight average molecular weight is too small, the adhesive residue may increase when the temperature-sensitive adhesive is peeled off from the adherend. On the other hand, if the weight average molecular weight is too large, the adhesive force is not easily lowered even if the temperature-sensitive adhesive is cooled to a predetermined temperature. The weight average molecular weight is a value obtained by measuring an ultraviolet curable side chain crystalline polymer by GPC and converting the obtained measurement value to polystyrene.

  The melting point of the ultraviolet curable side chain crystalline polymer is preferably 0 ° C. or higher, more preferably 10 to 60 ° C. The melting point can be arbitrarily set by changing the composition of the side chain crystalline polymer described above.

  Here, the melting point of the UV curable side chain crystalline polymer after UV curing is often substantially the same as the melting point of the UV curable side chain crystalline polymer before UV curing. Further, the ultraviolet curable side chain crystalline polymer after ultraviolet curing is crystallized at a temperature lower than the melting point, and exhibits a fluidity by phase transition at a temperature higher than the melting point. That is, the ultraviolet curable side-chain crystalline polymer reversibly causes a crystalline state and a fluid state in response to a temperature change in any state before and after ultraviolet irradiation. Therefore, the temperature-sensitive adhesive of this embodiment can be used repeatedly.

  The intensity of the ultraviolet rays applied to the temperature-sensitive adhesive of the present embodiment is not particularly limited as long as the ultraviolet-curable side chain crystalline polymer constituting the temperature-sensitive adhesive can be ultraviolet-cured. Moreover, ultraviolet irradiation may be performed with respect to the whole thermosensitive adhesive, and may be performed partially. The timing for performing the ultraviolet irradiation is not particularly limited, and may be performed at an arbitrary timing. For example, when the temperature-sensitive pressure-sensitive adhesive is peeled off from the adherend, the entire temperature-sensitive pressure-sensitive adhesive is irradiated with ultraviolet rays, so that a large reduction in the adhesive strength due to ultraviolet curing can be obtained.

  Further, if a photomask or the like is disposed on the surface of the temperature sensitive adhesive, the temperature sensitive adhesive can be partially irradiated with ultraviolet rays. In addition, a temperature-sensitive adhesive that has been partially irradiated with ultraviolet rays has a mixture of a reduced adhesive strength part that has been reduced in adhesive strength by UV curing and a non-reduced adhesive part that has not been exposed to ultraviolet light and has not been reduced in adhesive strength. It will be in the state. By adjusting the ratio, arrangement state, etc. of the adhesive strength reduced portion and the adhesive strength non-reduced portion by a photomask pattern or the like, the adhesive strength of the thermosensitive adhesive can be arbitrarily adjusted. When the temperature-sensitive adhesive that has been partially irradiated with ultraviolet rays is peeled off from the adherend, the adhesive strength non-decreasing portion that has not been UV-cured may be UV-cured if the adhesive strength is not sufficiently lowered.

  In addition, the temperature-sensitive adhesive may be embossed on the surface to form an uneven shape. Thereby, the contact area with respect to a to-be-adhered body can be adjusted, and the peelability from an to-be-adhered body can be improved. When the uneven shape is formed on the surface of the conventional temperature-sensitive adhesive, the uneven shape collapses when exposed to a high temperature, but the temperature-sensitive adhesive of this embodiment can be cured by ultraviolet rays, If it is UV-cured before exposure, the uneven shape can be maintained even when exposed to high temperatures.

  Various additives such as a tackifier, a plasticizer, an anti-aging agent, and a crosslinking agent can be added to the temperature-sensitive adhesive. When a crosslinking agent is added, it is preferable to copolymerize a polar monomer with an ultraviolet curable side chain crystalline polymer as a crosslinking component that undergoes a crosslinking reaction with the crosslinking agent. Examples of the polar monomer include carboxyl group-containing ethylenically unsaturated monomers such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, and fumaric acid. These may be used alone or in combination of two or more. May be used.

  The usage form of the temperature-sensitive adhesive according to the present embodiment is not particularly limited, and can be used, for example, in the form of a sheet, or by adding an appropriate solvent to the adhesive, It may be applied directly and dried.

  When the temperature-sensitive adhesive is formed into a sheet form and used as a temperature-sensitive adhesive sheet, the thickness thereof is 15 to 400 μm, preferably 120 to 150 μm. If the thickness of the pressure-sensitive adhesive sheet is too thin, the pressure-sensitive adhesive force is lowered and it is difficult to stick and fix the adherend. Moreover, when the thickness of the said adhesive sheet is too large, it will become difficult to prepare an adhesive sheet with uniform thickness.

  It is preferable to provide a release-treated film, that is, a release film, on both surfaces of the pressure-sensitive adhesive sheet. Examples of the release film include a film surface made of polyethylene terephthalate or the like and a release agent such as silicone applied thereto. In order to provide release films on both sides of the pressure-sensitive adhesive sheet, for example, a coating solution in which a pressure-sensitive adhesive is added to a solvent is applied on the release film and dried to obtain a pressure-sensitive adhesive sheet. May be arranged.

  Moreover, the said thermosensitive adhesive can also be used with the form of an adhesive tape. Next, an embodiment of the temperature-sensitive adhesive tape according to the present invention will be described. The temperature-sensitive adhesive tape according to this embodiment is provided with an adhesive layer made of the above-described temperature-sensitive adhesive of the present invention on one side or both sides of a base film.

  Examples of the base film include synthetic resins such as polyethylene, polyethylene terephthalate, polypropylene, polyester, polyamide, polyimide, polycarbonate, ethylene vinyl acetate copolymer, ethylene ethyl acrylate copolymer, ethylene polypropylene copolymer, and polyvinyl chloride. A film is mentioned.

  The said base film may consist of a single layer body or a multilayer body, and thickness is about 5-500 micrometers normally. In order to improve the adhesiveness with respect to an adhesive layer, surface treatments, such as a corona discharge process, a plasma process, a blast process, a chemical etching process, a primer process, can be given to a base film, for example.

  In order to provide the pressure-sensitive adhesive layer on one or both sides of the base film, a coating solution obtained by adding a pressure-sensitive adhesive to a solvent may be applied to one side or both sides of the base film and dried. The application can be generally performed by a knife coater, a roll coater, a calendar coater, a comma coater or the like. Further, depending on the coating thickness and the viscosity of the coating solution, a gravure coater, a rod coater or the like can be used.

  As thickness of an adhesive layer, it is preferable that it is 5-60 micrometers, it is more preferable that it is 10-60 micrometers, and it is further more preferable that it is 10-50 micrometers. The thickness of the adhesive layer on one side and the thickness of the adhesive layer on the other side may be the same or different.

  The composition of the pressure-sensitive adhesive layer on the other side is not particularly limited as long as the pressure-sensitive adhesive layer on the one side is composed of the temperature-sensitive pressure-sensitive adhesive of the present invention. When the pressure-sensitive adhesive layer on the other side is composed of, for example, a pressure-sensitive adhesive layer made of the temperature-sensitive pressure-sensitive adhesive of the present invention in the same manner as the pressure-sensitive adhesive layer on one side, the composition of the pressure-sensitive adhesive layer on one side and the pressure-sensitive adhesive on the other side The composition of the agent layer may be the same or different.

  Further, as the pressure-sensitive adhesive layer on the other surface, for example, a pressure-sensitive adhesive layer made of a pressure-sensitive adhesive can be used. The pressure-sensitive adhesive is an adhesive polymer, and examples thereof include natural rubber adhesives, synthetic rubber adhesives, styrene / butadiene latex base adhesives, and acrylic adhesives.

  The use of the temperature-sensitive adhesive of the present invention is not particularly limited, and is suitably used, for example, in a field where the atmospheric temperature in the manufacturing process of flat panel display (FPD) color filters, thin film transistors and the like is high. be able to.

  EXAMPLES Hereinafter, although a synthesis example and an Example are given and this invention is demonstrated in detail, this invention is not limited only to the following synthesis examples and Examples. In the following description, “part” means part by weight.

<Synthesis Example 1>
First, 43 parts of behenyl acrylate, 47 parts of methyl acrylate, 10 parts of 2-hydroxyethyl acrylate, and perbutyl ND (manufactured by NOF Corporation) as a polymerization initiator were mixed at a ratio of 0.4 part, and these were mixed with acetic acid. The mixture was adjusted to a solid content of 30 parts with a mixed solvent of ethyl: heptane = 7: 3 (weight ratio) to obtain a mixed solution.

  Subsequently, this mixed liquid was stirred at 55 ° C. for 4 hours to polymerize these monomers to obtain a side chain crystalline polymer solution. The obtained side chain crystalline polymer had a weight average molecular weight of 550,000 and a melting point of 55 ° C. In addition, the said weight average molecular weight is a value which measured the side chain crystalline polymer by GPC, and converted the obtained measured value into polystyrene. The said melting | fusing point is the value which measured the side chain crystalline polymer on the measurement conditions of 10 degree-C / min by DSC.

  100 parts of the obtained side chain crystalline polymer solution in terms of solid content was converted to 14 parts of 2-methacryloyloxyethyl isocyanate represented by the formula (I) (“Karenz MOI” manufactured by Showa Denko KK). Part, 0.1 part of dibutylhydroxytoluene (BHT) as an antioxidant and 0.2 part of di-n-butyltin dilaurate (DBTDL) as a catalyst were mixed at a temperature of 60 ° C. in a nitrogen gas atmosphere. The mixture was stirred for 4 hours to obtain an ultraviolet curable side chain crystalline polymer solution.

  A polyethylene terephthalate film having a thickness of 100 μm is obtained by adding 2.2 g of a photopolymerization initiator (“IRGACURE 500” manufactured by Ciba Japan Co., Ltd.) to 100 g of the obtained UV curable side chain crystalline polymer solution. (PET film) coated on one side and dried at 110 ° C. for 10 minutes, whereby a 40 μm thick adhesive layer made of an ultraviolet curable side chain crystalline polymer was formed on one side of the PET film. An adhesive tape was obtained. In this temperature-sensitive adhesive tape, the UV-curable side chain crystalline polymer constituting the adhesive layer had a weight average molecular weight of 620,000 and a melting point of 55 ° C.

<Synthesis Example 2>
First, a solution of a side chain crystalline polymer was obtained in the same manner as in Synthesis Example 1. Subsequently, the isocyanate compound added to the solution of the side chain crystalline polymer was replaced with 14 parts of 2-methacryloyloxyethyl isocyanate, and 2-acryloyloxyethyl isocyanate represented by the above formula (II) (Showa Denko ( Except for 13 parts of “Karenz AOI” manufactured by Co., Ltd.), a solution of an ultraviolet curable side chain crystalline polymer was obtained in the same manner as in Synthesis Example 1, and an ultraviolet curable side chain crystalline was obtained using this solution. A temperature-sensitive adhesive tape in which a 40 μm thick adhesive layer made of a polymer was formed on one side of a PET film was obtained. In this temperature-sensitive adhesive tape, the UV-curable side chain crystalline polymer constituting the adhesive layer had a weight average molecular weight of 650,000 and a melting point of 55 ° C.

<Synthesis Example 3>
First, a solution of a side chain crystalline polymer was obtained in the same manner as in Synthesis Example 1. Then, the isocyanate compound added to the solution of the side chain crystalline polymer is replaced with 14 parts of 2-methacryloyloxyethyl isocyanate, and 1,1-bis (acryloyloxymethyl) ethyl represented by the above formula (III) is used. An ultraviolet curable side chain crystalline polymer solution was obtained in the same manner as in Synthesis Example 1 except that 18 parts of isocyanate (“Karenz BEI” manufactured by Showa Denko Co., Ltd.) was used. A temperature-sensitive adhesive tape having a 40 μm-thick adhesive layer made of a curable side chain crystalline polymer formed on one side of a PET film was obtained. In this temperature-sensitive adhesive tape, the UV-curable side chain crystalline polymer constituting the adhesive layer had a weight average molecular weight of 680,000 and a melting point of 55 ° C.

<Comparative Synthesis Example 1>
First, a solution of a side chain crystalline polymer was obtained in the same manner as in Synthesis Example 1. Next, using this solution, a temperature-sensitive adhesive tape having a 40 μm-thick adhesive layer made of a side chain crystalline polymer formed on one side of a PET film was obtained.

Table 1 shows the side chain crystalline polymers and ultraviolet curable side chain crystalline polymers of Synthesis Examples 1 to 3 and Comparative Synthesis Example 1.

[Examples 1 to 3 and Comparative Example 1]
About each temperature-sensitive adhesive tape obtained in the said synthesis examples 1-3 and the comparative synthesis example 1, 180 degree peel strength was evaluated. The evaluation method is shown below, and the results are shown in Table 2.

<180 ° peel strength>
The 180 ° peel strength for the polyimide substrate at each ambient temperature of 80 ° C. and 23 ° C. was measured according to JIS Z0237. Specifically, a temperature-sensitive adhesive tape was attached to a polyimide substrate under the following conditions, and then peeled 180 ° using a load cell at a rate of 300 mm / min.

(80 ° C)
A temperature-sensitive adhesive tape was attached to a polyimide substrate at an ambient temperature of 80 ° C. and allowed to stand for 20 minutes, and then peeled 180 °.

(23 ° C)
First, a temperature-sensitive adhesive tape is attached to a polyimide substrate at an ambient temperature of 80 ° C., the ambient temperature is increased to 200 ° C., and the ambient temperature is allowed to stand for 20 minutes, and then the ambient temperature is lowered to 23 ° C. Let stand for 20 minutes at temperature.

Next, the temperature-sensitive adhesive tapes obtained in Synthesis Examples 1 to 3 were irradiated with ultraviolet rays to cure the pressure-sensitive adhesive layer, and then peeled 180 °. Further, the temperature-sensitive adhesive tape obtained in Comparative Synthesis Example 1 was peeled 180 ° without being irradiated with ultraviolet rays. In addition, ultraviolet irradiation uses the handy type UV curing device “HLR 100T-2” manufactured by As One Search Co., Ltd., and the entire pressure-sensitive adhesive layer is irradiated with 10 mW / cm ² ultraviolet rays irradiated from the device from the PET film side. For 1 minute at room temperature (23 ° C.).

  Moreover, the destruction state in each atmospheric temperature was evaluated visually. In Table 2, “interfacial fracture” indicates that peeling occurred between the pressure-sensitive adhesive layer and the polyimide substrate. “Cohesive failure” indicates that the pressure-sensitive adhesive layer has been destroyed. “Stick slip” indicates that the peeling progressed intermittently when the temperature-sensitive adhesive tape was peeled from the polyimide substrate. When stick-slip occurs, the load applied to the adherend increases locally, so that the adherend is easily damaged.

  As is clear from Table 2, Examples 1 to 3 have a lower 180 ° peel strength at 23 ° C. and a better fracture state than Comparative Example 1, so even when exposed to high temperatures, It turns out that peeling is easy.

Claims (7)

A temperature-sensitive pressure-sensitive adhesive containing a side-chain crystalline polymer, the adhesive strength of which decreases at a temperature below the melting point of the side-chain crystalline polymer,
The side chain crystalline polymer is obtained by polymerizing (meth) acrylate having a linear alkyl group having 16 or more carbon atoms, methyl (meth) acrylate, and (meth) acrylate having a hydroxyalkyl group, A temperature-sensitive adhesive, which is an ultraviolet curable side chain crystalline polymer having an ultraviolet curable functional group.   The temperature-sensitive adhesive according to claim 1, wherein the ultraviolet curable side chain crystalline polymer is obtained by reacting a side chain crystalline polymer with a compound having an ultraviolet curable functional group.   The temperature-sensitive adhesive according to claim 1 or 2, wherein the ultraviolet curable functional group is a (meth) acryloyloxy group.   The temperature-sensitive adhesive according to any one of claims 1 to 3, wherein the ultraviolet curable side chain crystalline polymer is crystallized at a temperature lower than the melting point and exhibits fluidity at a temperature higher than the melting point.   The temperature-sensitive adhesive according to any one of claims 1 to 4, wherein the adhered adherend is removed at a temperature lower than the melting point after being exposed to a temperature of 100 ° C or higher.   The temperature sensitive adhesive sheet which consists of a temperature sensitive adhesive in any one of Claims 1-5.   A temperature-sensitive adhesive tape, wherein the pressure-sensitive adhesive layer comprising the temperature-sensitive adhesive according to any one of claims 1 to 5 is provided on one side or both sides of a base film.