JP5358086B2 - Temperature sensitive adhesive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a temperature sensitive adhesive whose adhesive power can be sufficiently reduced when it is removed. <P>SOLUTION: The temperature sensitive adhesive comprises a pressure sensitive adhesive, a side-chain crystalline polymer, and a foaming agent. The pressure sensitive adhesive is a copolymer of a reactive polysiloxane compound and a monomer copolymerizable with the reactive polysiloxane compound. The temperature sensitive adhesive has a reduced adhesive power at the melting point or higher of the side-chain crystalline polymer. The reactive polysiloxane compound is preferably a one terminal reactive polysiloxane compound. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a temperature-sensitive adhesive used when temporarily fixing a component or the like.

  Conventionally, adhesives for temporary fixing of parts used in the fields of electronic parts, semiconductor wafers, liquid crystals, etc. can be fixed with a predetermined adhesive force, and the adhesive strength decreases when peeling from the part. It is required to be easily removable. Examples of such an adhesive include a foaming adhesive and a temperature sensitive adhesive.

The foamed pressure-sensitive adhesive contains a foaming agent in a predetermined pressure-sensitive adhesive, and the adhesive strength is reduced by expansion or foaming of the foaming agent by heat treatment (for example, see Patent Documents 1 and 2).
However, there is a problem that the adhesive force is not sufficiently lowered by the foaming agent.

The temperature-sensitive pressure-sensitive adhesive contains a side chain crystalline polymer in a predetermined pressure-sensitive adhesive, and when the heat treatment is performed to a temperature equal to or higher than the melting point of the side chain crystalline polymer, the side chain crystalline polymer Shows fluidity, and this reduces the adhesive strength (see, for example, Patent Document 3).
However, even if the adhesive strength is reduced by the side chain crystalline polymer, the adhesive strength is not completely lost, so some force must be applied when removing it from the part.

On the other hand, some parts need to be removed from the adhesive by shifting in the lateral direction.
However, with the above-described conventional pressure-sensitive adhesive, the adhesive force cannot be sufficiently reduced, so that the components cannot be shifted in the lateral direction. For this reason, development of the adhesive which can fully reduce adhesive force at the time of removal is desired.

JP 63-33487 A JP-A-5-43851 JP 2000-355684 A

  The subject of this invention is providing the temperature sensitive adhesive which can fully reduce adhesive force at the time of removal.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors contain a pressure-sensitive adhesive, a side chain crystalline polymer, and a foaming agent, and the pressure-sensitive adhesive comprises a reactive polysiloxane compound, In the case of a copolymer of this reactive polysiloxane compound and a copolymerizable monomer, the present inventors have found a new fact that the adhesive force can be sufficiently reduced upon removal, and have completed the present invention. .

That is, the temperature-sensitive adhesive of the present invention has the following configuration.
(1) A pressure-sensitive adhesive, a side chain crystalline polymer, and a foaming agent, the pressure-sensitive adhesive comprising a reactive polysiloxane compound and a monomer copolymerizable with the reactive polysiloxane compound A temperature-sensitive pressure-sensitive adhesive, wherein the adhesive strength is reduced at a temperature equal to or higher than the melting point of the side chain crystalline polymer.
(2) The temperature-sensitive adhesive according to (1), wherein the reactive polysiloxane compound is a one-end reactive polysiloxane compound.
(3) The temperature-sensitive adhesive according to (1) or (2), wherein a frictional resistance at 23 ° C. after expansion or foaming of the foaming agent by heat treatment is 400 g or less.
(4) The side chain crystalline polymer has a melting point of 50 ° C. or higher, crystallizes at a temperature lower than the melting point, and exhibits fluidity at a temperature higher than the melting point, according to any one of (1) to (3). Temperature sensitive adhesive.
(5) The temperature-sensitive adhesive according to any one of (1) to (4), wherein the side chain crystalline polymer has a weight average molecular weight of 3,000 to 30,000.
(6) The feeling according to any one of (1) to (5), wherein the side chain crystalline polymer is contained in a proportion of 0.1 to 20 parts by weight with respect to 100 parts by weight of the pressure-sensitive adhesive. Warm adhesive.
(7) The temperature-sensitive adhesive according to any one of (1) to (6), wherein the foaming agent is contained at a ratio of 0.1 to 100 parts by weight with respect to 100 parts by weight of the pressure-sensitive adhesive. Agent.
(8) The temperature-sensitive adhesive according to any one of (1) to (7), wherein the adhesive strength at 23 ° C. is 0.1 to 20 N / 25 mm.
(9) The temperature-sensitive adhesive according to any one of (1) to (8), wherein the thickness is 5 to 50 μm.

  The pressure-sensitive adhesive sheet of the present invention has a pressure-sensitive adhesive layer provided on one side or both sides of a base film, and the pressure-sensitive adhesive layer is any one of (1) to (9). It is characterized by comprising.

According to the present invention, since the side chain crystalline polymer is contained, the side chain crystalline polymer exhibits fluidity and the adhesive strength is reduced by heating to a temperature equal to or higher than the melting point of the side chain crystalline polymer. In addition, since it contains a foaming agent and a pressure-sensitive adhesive composed of a copolymer having a reactive polysiloxane compound as one of the monomers, in addition to the decrease in the adhesive strength due to the side chain crystalline polymer, A reduction in force and releasability due to the polysiloxane compound are added. Therefore, at the time of removal, there is an effect that the adhesive force can be sufficiently reduced and the attachment can be easily removed.
In particular, when the temperature-sensitive adhesive according to the present invention is applied to temporary fixing for removing the adherend (component) in the lateral direction, the usefulness of the present invention is further improved.

  The temperature-sensitive adhesive of the present invention contains a pressure-sensitive adhesive, a side chain crystalline polymer, and a foaming agent. The said temperature sensitive adhesive means the adhesive from which adhesive force changes according to a temperature change.

<Pressure sensitive adhesive>
The pressure-sensitive adhesive is a polymer having tackiness, and is a copolymer of a reactive polysiloxane compound and a monomer copolymerizable with the reactive polysiloxane compound. The reactive polysiloxane compound means a polysiloxane compound having a reactive functional group and having a siloxane bond in the main chain. The reactive polysiloxane compound may be in the form of a wax at room temperature (23 ° C.), but is preferably in the form of an oil that exhibits fluidity at room temperature (ie, silicone oil) for efficient polymerization.

  Examples of the functional group showing the reactivity include ethylenically unsaturated double bonds such as vinyl group, allyl group, (meth) acryl group, (meth) acryloyl group, (meth) acryloxy group; epoxy group (glycidyl group and An epoxycycloalkyl group), mercapto group, carbinol group, carboxyl group, silanol group, phenol group, amino group, hydroxyl group and the like.

  These functional groups may be introduced into the side chain of the main chain, or may be introduced into both ends or one end of the main chain. That is, depending on the bonding position of the functional group to be introduced, there are four types of so-called side chain type, double-ended type, single-ended type, and double-ended side chain type, and particularly excellent adhesiveness and releasability can be obtained. Therefore, the one-end type (that is, one-end reactive polysiloxane compound) is preferable.

［式中、Ｒ₁はアルキル基を示す。Ｒ₂は基：ＣＨ₂＝ＣＨＣＯＯＲ³−またはＣＨ₂＝Ｃ（ＣＨ₃）ＣＯＯＲ³−（式中、Ｒ³はアルキレン基を示す。）を示す。ｎは５〜２００の整数を示す。］ Specific examples of the one-terminal reactive polysiloxane compound include a modified polydimethylsiloxane compound represented by the following general formula (I).

[Wherein R ₁ represents an alkyl group. R ₂ represents a group: CH ₂ ═CHCOOR ³ — or CH ₂ ═C (CH ₃ ) COOR ³ — (wherein R ³ represents an alkylene group). n shows the integer of 5-200. ]

  Examples of the alkyl group include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, s-butyl group, t-butyl group, pentyl group, isopentyl group, neopentyl group, and hexyl group. C1-C6 linear or branched alkyl groups, such as these, are mentioned.

  Examples of the alkylene group include linear or branched alkylene groups having 1 to 6 carbon atoms such as a methylene group, an ethylene group, a trimethylene group, a methylethylene group, a propylene group, a tetramethylene group, a pentamethylene group, and a hexamethylene group. Etc.

［式中、Ｒ₁，ｎは、前記と同じである。］ Specific examples of the modified polydimethylsiloxane compound represented by the general formula (I) include compounds represented by the following general formula (II).

[Wherein R ₁ and n are the same as defined above. ]

  Examples of such modified polydimethylsiloxane compounds include trade names “X-22-2404”, “X-24-8201”, “X-22-174DX”, “ One terminal reactive silicone oil such as “X-22-2426” and the like may be mentioned, and these may be used alone or in combination of two or more.

  Although it does not specifically limit as a monomer copolymerizable with the said reactive polysiloxane compound, An acrylic monomer is preferable when it is excellent in adhesiveness. Examples of the acrylic monomer include acrylic acid ester and / or methacrylic acid ester (hereinafter referred to as (meth) acrylate) having an alkyl group having 1 to 12 carbon atoms. Examples of the (meth) acrylate include ethylhexyl (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, and the like. These may be used alone or in combination of two or more. May be used. Moreover, you may use the (meth) acrylate which has a hydroxyalkyl group as another copolymerization component. Examples of such (meth) acrylates include hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxyhexyl (meth) acrylate, and the like. These may be used alone or in combination of two or more. Also good.

  The ratio of the reactive polysiloxane compound and the monomer copolymerizable with the reactive polysiloxane compound is 1 to 30 parts by weight of the reactive polysiloxane compound, preferably 1 to 10 parts by weight, based on the total amount of monomers. The monomer copolymerizable with the reactive polysiloxane compound is 70 to 99 parts by weight, preferably 90 to 99 parts by weight. On the other hand, if the reactive polysiloxane compound is less than 1 part by weight, the releasability due to the polysiloxane compound may not be obtained. If the reactive polysiloxane compound is more than 30 parts by weight, There is a risk that the force will be low and the parts cannot be fixed.

  The copolymer preferably has a weight average molecular weight of 250,000 to 1,000,000. On the other hand, when the weight average molecular weight of the copolymer is less than 250,000, when removing the temperature-sensitive adhesive from the part, the temperature-sensitive adhesive remains on the part, so-called adhesive residue increases. There is a fear. On the other hand, if the weight average molecular weight is larger than 1,000,000, the cohesive force becomes too high and the adhesive force may be lowered. The weight average molecular weight is a value obtained by measuring the copolymer by gel permeation chromatography (GPC) and converting the obtained measurement value into polystyrene.

  The polymerization method for polymerizing the reactive polysiloxane compound and the monomer copolymerizable with the reactive polysiloxane compound is not particularly limited, and for example, a solution polymerization method, a bulk polymerization method, a suspension polymerization method, Examples thereof include an emulsion polymerization method. For example, when a solution polymerization method is employed, a reactive polysiloxane compound and a monomer copolymerizable with the reactive polysiloxane compound are mixed in an appropriate solvent, and the temperature is about 50 to 70 ° C. for about 4 to 6 hours. By stirring, a copolymer of a reactive polysiloxane compound and a monomer copolymerizable with the reactive polysiloxane compound can be obtained.

<Side-chain crystalline polymer>
The side chain crystalline polymer is preferably crystallized at a temperature below the melting point and exhibits fluidity at a temperature above the melting point. That is, the polymer is preferably a polymer that reversibly causes a crystalline state and a fluid state in response to a temperature change. As a result, the temperature-sensitive adhesive can secure adhesive force at a temperature below the melting point, and the side-chain crystalline polymer flows at temperatures above the melting point. It will be in a state and the fall of the adhesive force of a temperature sensitive adhesive will be expressed.

  In the present invention, the melting point means a temperature at which a specific portion of the polymer originally aligned in an ordered arrangement becomes disordered by an equilibrium process, and is 10 ° C./min by a differential thermal scanning calorimeter (DSC). It is a value obtained by measuring under the measurement conditions. The melting point of the side chain crystalline polymer according to the present invention is 50 ° C. or higher, preferably 50 to 70 ° C. As a result, since the side chain crystalline polymer is in a crystalline state at room temperature, the temperature-sensitive adhesive exhibits adhesive strength at room temperature, so that workability is improved.

  The composition of the side chain crystalline polymer is, for example, 30 to 99 parts by weight of a (meth) acrylate having a linear alkyl group having 16 or more carbon atoms, preferably 16 to 22 carbon atoms, and an alkyl group having 1 to 6 carbon atoms. Examples include polymers obtained by polymerizing 0 to 70 parts by weight of acrylic acid ester or methacrylic acid ester having 1 to 10 parts by weight of polar monomers.

  Examples of the (meth) acrylate having a linear alkyl group having 16 or more carbon atoms as a side chain include cetyl (meth) acrylate, stearyl (meth) acrylate, eicosyl (meth) acrylate, and behenyl (meth) acrylate. Examples thereof include (meth) acrylates having 16 to 22 linear alkyl groups, and these may be used alone or in combination of two or more. Examples of the (meth) acrylate having an alkyl group having 1 to 6 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, and the like. Alternatively, two or more kinds may be mixed and used. Examples of polar monomers include carboxyl group-containing ethylenically unsaturated monomers such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, and fumaric acid; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meta ), Ethylenically unsaturated monomers having hydroxyl groups such as acrylate and 2-hydroxyhexyl (meth) acrylate, and the like. These may be used alone or in combination of two or more.

  The weight average molecular weight of the side chain crystalline polymer is 3,000 to 30,000, preferably 5,000 to 25,000. When the weight average molecular weight is within this range, when the side-chain crystalline polymer exhibits fluidity at a temperature equal to or higher than the melting point, the adhesive force of the temperature-sensitive adhesive is sufficiently reduced. On the other hand, when the weight average molecular weight is less than 3,000, the adhesive residue may increase when the temperature-sensitive adhesive is removed from the part. On the other hand, if the weight average molecular weight exceeds 30,000, the adhesive force may not easily decrease even if the side chain crystalline polymer exhibits fluidity at a temperature higher than the melting point. The weight average molecular weight is a value obtained by measuring the side chain crystalline polymer by GPC and converting the obtained measurement value to polystyrene.

  The polymerization method is not particularly limited, and examples thereof include a solution polymerization method, a bulk polymerization method, a suspension polymerization method, and an emulsion polymerization method. For example, when the solution polymerization method is employed, the monomer can be polymerized by mixing the monomer exemplified above in an appropriate solvent and stirring at about 70 to 90 ° C. for about 4 to 6 hours.

  The side chain crystalline polymer may be contained in an amount of 0.1 to 20 parts by weight, preferably 0.5 to 10 parts by weight with respect to 100 parts by weight of the pressure sensitive adhesive. Thereby, when the side chain crystalline polymer exhibits fluidity at a temperature equal to or higher than the melting point, the adhesive force of the temperature-sensitive adhesive is sufficiently reduced. On the other hand, when the content of the side chain crystalline polymer is less than 0.1 parts by weight, the adhesive strength is reduced even when the temperature-sensitive adhesive is heated to a temperature higher than the melting point of the side chain crystalline polymer. It becomes difficult to do. On the other hand, when the amount is more than 20 parts by weight, the adhesive force is lowered, and there is a possibility that the component cannot be fixed.

<Foaming agent>
The foaming agent is not particularly limited, and any ordinary chemical foaming agent and physical foaming agent can be employed. Chemical foaming agents include pyrolytic and reactive organic foaming agents and inorganic foaming agents.

  Examples of the pyrolytic organic foaming agent include various azo compounds (such as azodicarbonamide), nitroso compounds (such as N, N′-dinitrosopentamethylenetetramine), and hydrazine derivatives [4,4′-oxybis (benzene). Sulfonyl hydrazide) and the like], semicarbazide compounds (hydrazodicarbonamide and the like), azide compounds, tetrazole compounds and the like. Examples of the reactive organic foaming agent include isocyanate compounds.

  Examples of the thermal decomposition type inorganic foaming agent include bicarbonate / carbonate (sodium bicarbonate, etc.), nitrite / hydride, etc. Examples of the reaction type inorganic foaming agent include sodium bicarbonate and the like. The combination with an acid, the combination of hydrogen peroxide and yeast, the combination of zinc powder and an acid, etc. are mentioned.

  Examples of the physical foaming agent include organic physical foaming agents such as aliphatic hydrocarbons such as butane, pentane and hexane, chlorohydrocarbons such as dichloroethane and dichloromethane, and fluorochlorohydrocarbons such as chlorofluorocarbons; air, carbonic acid Examples thereof include inorganic physical foaming agents such as gas and nitrogen gas.

  As other foaming agents, microencapsulated thermally expandable fine particles (so-called microballoon foaming agents) can be employed. The microballoon foaming agent is obtained by encapsulating a heat-expandable substance made of a solid, liquid, or gas inside a polymer shell made of a thermoplastic or thermosetting resin. The microballoon foaming agent expands in volume by 40 times or more by heating, and a foam in the form of closed cells is obtained. Therefore, the microballoon foaming agent has a characteristic that the expansion ratio is considerably larger than that of a normal foaming agent.

  The foaming agent is contained in an amount of 0.1 to 100 parts by weight, preferably 1 to 50 parts by weight, based on 100 parts by weight of the pressure-sensitive adhesive. On the other hand, if the content of the foaming agent is less than 0.1 parts by weight, the adhesive force cannot be sufficiently reduced by the foaming agent, and the adhesive force may be difficult to decrease. On the other hand, when the amount is more than 100 parts by weight, unevenness derived from the foaming agent is generated on the surface of the temperature-sensitive adhesive, the surface property is lowered, and the adhesive force may be lowered.

  The temperature at which the foaming agent expands or foams is not particularly limited, but is usually 180 ° C. or lower, and is a temperature of 80 ° C. or higher for suppressing foaming during coating drying. Is preferred. Although the average particle diameter of a foaming agent is not specifically limited, Usually, it is about 5-50 micrometers. The average particle diameter is a value obtained by measuring with a particle size distribution measuring apparatus.

  The temperature-sensitive adhesive according to the present invention has a frictional resistance at 23 ° C. of 400 g or less, preferably 200 g or less, more preferably 5 after the foaming agent in the temperature-sensitive adhesive is expanded or foamed by heat treatment. It should be ~ 200 g. With such a frictional resistance, when the adhesive force is lowered, the surface slipperiness becomes excellent, and the adherend (part) can be easily removed by shifting in the lateral direction. As will be described later, after the foaming agent is expanded or foamed by heat treatment, the frictional resistance is the friction resistance against an acrylic resin plate at an ambient temperature of 23 ° C., the speed is 300 mm / min, and the area is 25 mm × 25 mm. The value obtained by measurement using a frictional resistance measuring machine under the condition of a weight of 50 g.

  The temperature-sensitive adhesive according to the present invention preferably has an adhesive strength at 23 ° C. of 0.1 to 20 N / 25 mm. On the other hand, if the adhesive strength is less than 0.1 N / 25 mm, the component may not be fixed, and if it exceeds 20 N / 25 mm, the adhesive strength may be difficult to decrease. The adhesive strength is a value obtained by measuring the peel strength (adhesive strength) for a polyethylene terephthalate film at an ambient temperature of 23 ° C. according to JIS Z0237.

  In order to set the adhesive force and the frictional resistance to predetermined values, for example, the ratio of the side chain crystalline polymer and / or the foaming agent to the pressure sensitive adhesive, the composition of the pressure sensitive adhesive and / or the side chain crystalline polymer, and the molecular weight. It can be arbitrarily performed by changing etc. As a specific example, if the ratio of the side chain crystalline polymer and / or the foaming agent to the pressure-sensitive adhesive is reduced within the above-described range, the adhesive force can be increased. On the contrary, if the ratio of the side chain crystalline polymer and / or the foaming agent to the pressure-sensitive adhesive is increased within the above range, the frictional resistance can be lowered.

  The temperature-sensitive adhesive according to the present invention is preferably used with a thickness of 5 to 50 μm. In addition, the said adhesive force and frictional resistance can be adjusted also by adjusting the thickness of this temperature sensitive adhesive. That is, if the thickness is increased within the above range, the adhesive force can be increased. On the contrary, if the thickness is reduced within the above range, the frictional resistance can be lowered.

  Moreover, in order to raise the cohesion force of a temperature sensitive adhesive, you may add a crosslinking agent. Examples of the crosslinking agent include isocyanate compounds, aziridine compounds, epoxy compounds, metal chelate compounds, and the like. You may add arbitrary components like a plasticizer, a tackifier, a filler, etc. as needed. Examples of the tackifier include special rosin ester type, terpene phenol type, petroleum resin type, high hydroxyl group rosin ester type, hydrogenated rosin ester type and the like.

  The usage form of the temperature-sensitive adhesive of the present invention is not particularly limited, and can be used, for example, in the form of a film or a sheet, or by adding a suitable solvent to the temperature-sensitive adhesive. You may make it apply | coat directly to a kimono and dry.

  Moreover, you may use the temperature sensitive adhesive of this invention as an adhesive sheet. In this case, what is necessary is just to provide the adhesive layer which consists of a thermosensitive adhesive of this invention in the single side | surface or both surfaces of a base film. Examples of the base film include polyethylene film, polyethylene terephthalate film, polypropylene film, polyester film, polyamide film, polyimide film, polycarbonate film, ethylene vinyl acetate copolymer film, ethylene ethyl acrylate copolymer film, and ethylene polypropylene copolymer. Examples thereof include synthetic resin films such as a coalesced film and a polyvinyl chloride film. Moreover, this film may consist of a single layer body or these multilayer bodies, and thickness is about 5-500 micrometers normally. In order to improve the adhesion to the pressure-sensitive adhesive layer, the surface of the base film may be subjected to surface treatment such as corona discharge treatment, plasma treatment, blast treatment, chemical etching treatment, and primer treatment.

  In general, a knife coater, a roll coater, a calendar coater, a comma coater or the like is often used to provide the adhesive layer on the base film. Depending on the coating thickness and material viscosity, a gravure coater, a rod coater or the like can be used. The thickness of the pressure-sensitive adhesive layer is preferably 5 to 50 μm.

  Next, an example of using the thermosensitive adhesive of the present invention in a usage form of an adhesive sheet will be described based on the drawings. FIG. 1 is a schematic explanatory view showing a method of dicing an electronic component using the pressure-sensitive adhesive sheet of the present invention.

  First, as shown to Fig.1 (a), the electronic component 3 is fixed on the base 1 through the adhesive sheet 2 of this invention. That is, the pressure-sensitive adhesive sheet 2 is provided with a pressure-sensitive adhesive layer made of the temperature-sensitive pressure-sensitive adhesive of the present invention (not shown) on both surfaces of the base film. The agent layers are respectively attached to the base 1 to fix the electronic component 3 on the base 1.

  After fixing the electronic component 3 on the base 1, the electronic component 3 is cut. As shown in FIG. 1B, the cutting is performed by the rotary blade 4, thereby forming a plurality of cut pieces 5. At the time of this cutting, lateral force and vibration are applied to the electronic component 3 by being pushed by the rotary blade, and the electronic component 3 is likely to be scattered from the adhesive sheet. However, by using the adhesive sheet 2, the scattering is suppressed. can do.

  Next, the adhesive sheet 2 is heat-treated. The heating is performed so that the temperature is equal to or higher than the melting point of the side chain crystalline polymer in the pressure-sensitive adhesive layer and the foaming agent expands or foams. As a result, the side chain crystalline polymer exhibits fluidity at a temperature equal to or higher than the melting point, and further, the foaming agent expands or foams, and the releasability due to the polysiloxane compound is added, so that the adhesive strength of the adhesive layer is sufficient. To drop. In this state, as shown in FIG. 1 (c), the cut piece 5 is shifted from the adhesive sheet 2 in the lateral direction (direction indicated by the arrow A). At this time, since the surface of the pressure-sensitive adhesive layer is excellent in surface slipperiness, it can be easily removed.

  In the above, the case where the pressure-sensitive adhesive sheet (temperature-sensitive pressure-sensitive adhesive) according to the present invention is used for dicing of electronic parts has been described. However, the present invention is not limited to this, and for example, a multilayer ceramic inductor, a resistor It can be similarly applied to the manufacture of ceramic devices such as ceramics, ferrite, sensor elements, thermistors, varistors, piezoelectric ceramics, semiconductor wafers, and liquid crystals.

  Hereinafter, although the thermosensitive adhesive of this invention is demonstrated in detail, giving a synthesis example and an Example, 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: Side chain crystalline polymer)
40 parts of behenyl acrylate (manufactured by NOF Corporation), 35 parts of stearyl acrylate (manufactured by NOF Corporation), 20 parts of methyl acrylate (manufactured by Nippon Shokubai Co., Ltd.), 5 parts of acrylic acid, dodecyl mercaptan (manufactured by Kao Corporation) 6 parts and perhexyl PV (manufactured by NOF Corporation) were mixed with 100 parts by weight of toluene at a ratio of 1 part, and stirred at 80 ° C. for 5 hours to polymerize these monomers. The resulting copolymer had a weight average molecular weight of 7,900 and a melting point of 51 ° C.

(Synthesis Example 2: Pressure-sensitive adhesive)
52 parts of ethylhexyl acrylate (manufactured by Nippon Shokubai Co., Ltd.), 35 parts of methyl acrylate, 8 parts of hydroxyethyl acrylate (manufactured by Nippon Shokubai Co., Ltd.), modified polydimethylsiloxane compound (“one-end reactivity” manufactured by Shin-Etsu Chemical Co., Ltd.) Silicone oil ”, trade name“ X-22-174DX ”) 5 parts, and perbutyl ND (Nippon Yushi Co., Ltd.) 0.5 parts in ethyl acetate / toluene (70/30) 230 weights, respectively. The monomers were polymerized by mixing at 60 ° C. for 5 hours. The weight average molecular weight of the obtained copolymer was 480,000.

(Comparative Synthesis Example 1: Pressure-sensitive adhesive)
Acetic acid at a ratio of 52 parts of ethylhexyl acrylate (manufactured by Nippon Shokubai Co., Ltd.), 40 parts of methyl acrylate, 8 parts of hydroxyethyl acrylate (manufactured by Nippon Shokubai Co., Ltd.) and 0.5 part of perbutyl ND (manufactured by Nippon Oil & Fats Co., Ltd.) These monomers were polymerized by mixing with 230 parts by weight of ethyl / n-heptane (70/30) and stirring at 60 ° C. for 5 hours. The weight average molecular weight of the obtained copolymer was 470,000.

  Table 1 shows the copolymers obtained in Synthesis Examples 1 and 2 and Comparative Synthesis Example 1. In addition, the said weight average molecular weight is a value which measured the copolymer by GPC and converted the obtained measured value into polystyrene. The melting point of the copolymer of Synthesis Example 1 was measured by DSC under measurement conditions of 10 ° C./min.

[Examples 1 to 10 and Comparative Examples 1 to 6]
<Creation of adhesive sheet>
First, a copolymer solution was prepared using the side chain crystalline polymer obtained above and a pressure-sensitive adhesive in combinations shown in Table 2. Subsequently, a foaming agent was added to the copolymer solution at a ratio shown in Table 2. As the foaming agent, microencapsulated thermally expandable fine particles (“551DU40” manufactured by EXPANCEL) were used. Further, in Table 2, the addition amounts of the side chain crystalline polymer and the foaming agent are values relative to 100 parts by weight of the pressure sensitive adhesive.

  This copolymer solution was applied to one side of a base film (polyethylene terephthalate film) having a thickness of 100 μm, and this was dried to form an adhesive layer having the thickness shown in Table 2 to obtain each adhesive sheet ( Examples 1 to 10 and Comparative Examples 1 to 6 in Table 2).

<Evaluation>
About each adhesive sheet obtained above, peel strength, peelability, and frictional resistance were evaluated. Each evaluation method is shown below, and the results are also shown in Table 2.

(Peel strength)
The peel strength (adhesive strength) for the polyethylene terephthalate film at 23 ° C. was measured according to JIS Z0237.

(Peelability)
After sticking the pressure-sensitive adhesive sheet to a polyethylene terephthalate film at 23 ° C., the pressure-sensitive adhesive sheet is heated to 130 ° C. (temperature higher than the melting point of the side chain crystalline polymer and the foaming agent expands), whereby the pressure-sensitive adhesive sheet becomes polyethylene terephthalate. It was visually observed whether or not the film was peeled only by its own weight. The following criteria were used.
○: Peeled only by the tape's own weight ×: Not peeled only by the tape's own weight

(Frictional resistance)
First, after sticking an adhesive sheet to an acrylic resin plate at 23 ° C., the foaming agent in the adhesive layer was expanded by raising the temperature to 130 ° C. Subsequently, it cooled to 23 degreeC and measured the frictional resistance in this 23 degreeC on the following measuring conditions.
Friction resistance measuring machine: “Triboa Gear HEIDON-14DR” manufactured by Shinto Chemical Co., Ltd.
Speed: 300mm / min Area: Length 25mm x Width 25mm
Weight: 50g
Substrate: Acrylic resin plate

  As is apparent from Table 2, it can be seen that the adhesive sheets of Examples 1 to 10 are excellent in peelability and friction resistance while maintaining the peel strength at 23 ° C., that is, the predetermined adhesive force. In contrast, the pressure-sensitive adhesive sheets of Comparative Examples 1 and 2 are simply pressure-sensitive adhesives in which the pressure-sensitive adhesive does not contain a reactive polysiloxane compound as a copolymerization component, and do not contain side-chain crystalline polymers. The results were inferior in resistance and frictional resistance. Since the pressure-sensitive adhesive sheets of Comparative Examples 3 and 4 did not contain a side chain crystalline polymer, the results showed inferior peelability and friction resistance. The pressure-sensitive adhesive sheets of Comparative Examples 5 and 6 showed results inferior in frictional resistance because the pressure-sensitive adhesive was simply a pressure-sensitive adhesive that did not contain a reactive polysiloxane compound as a copolymerization component.

It is a schematic explanatory drawing which shows the method of dicing an electronic component using the adhesive sheet of this invention.

Explanation of symbols

1 pedestal 2 adhesive sheet 3 electronic component 4 rotary blade 5 cutting piece

Claims (8)

Containing a pressure sensitive adhesive, a side chain crystalline polymer, and a foaming agent;
The pressure-sensitive adhesive is a copolymer of a one-end reactive polysiloxane compound represented by the following general formula (I) and a monomer copolymerizable with the one-end reactive polysiloxane compound,
The side chain crystalline polymer is a copolymer obtained by polymerizing a (meth) acrylate having a linear alkyl group having at least 16 carbon atoms and a polar monomer,
While expressing a decrease in adhesive strength at a temperature equal to or higher than the melting point of the side chain crystalline polymer ,
A temperature-sensitive adhesive having a frictional resistance at 23 ° C. of 400 g or less after the foaming agent is expanded or foamed by heat treatment .

[Wherein R ₁ represents an alkyl group. R ₂ represents a group: CH ₂ ═CHCOOR ³ — or CH ₂ ═C (CH ₃ ) COOR ³ — (wherein R ³ represents an alkylene group). n shows the integer of 5-200. ] The side-chain crystalline polymer has a melting point at 50 ° C. or higher, heat-sensitive adhesive agent according to claim 1 Symbol placement shows fluidity at crystallized and a temperature above the melting point at a temperature lower than the melting point. The temperature-sensitive adhesive according to claim 1 or 2, wherein the side chain crystalline polymer has a weight average molecular weight of 3,000 to 30,000. The temperature-sensitive adhesive according to any one of claims 1 to 3 , wherein the side chain crystalline polymer is contained in a proportion of 0.1 to 20 parts by weight with respect to 100 parts by weight of the pressure-sensitive adhesive. The temperature-sensitive adhesive according to any one of claims 1 to 4 , wherein the foaming agent is contained at a ratio of 0.1 to 100 parts by weight with respect to 100 parts by weight of the pressure-sensitive adhesive. The temperature-sensitive adhesive according to any one of claims 1 to 5 , wherein the adhesive force at 23 ° C is 0.1 to 20 N / 25 mm. The temperature-sensitive adhesive according to any one of claims 1 to 6 , which has a thickness of 5 to 50 µm. The pressure-sensitive adhesive layer to a single-sided or adhesive sheet provided on both sides of the base film, adhesive sheet, wherein the adhesive layer is made of a heat-sensitive adhesive agent according to any one of claims 1-7 .

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