KR102422205B1 - Adhesive composition and adhesive tape - Google Patents

Abstract

(R¹, R²는 탄화수소기 또는 산소 원자 함유 탄화수소기로 R²의 탄소 원자수는 R¹의 탄소 원자수보다 많고, R³은 수소 원자 또는 메틸기, x는 1~3이다.)A (meth)acrylic system comprising a monomer unit of two or more types of hydroxyl group-containing (meth)acrylate monomers represented by formulas (A1) and (A2) and a monomer unit of 5.1 to 20% by mass of a carboxyl group-containing monomer (A3) A pressure-sensitive adhesive composition containing a polymer (A) and an epoxy-based crosslinking agent (B), and an adhesive tape using the same are disclosed.

(R ¹ , R ² is a hydrocarbon group or an oxygen atom-containing hydrocarbon group, the number of carbon atoms in R ² is greater than the number of carbon atoms in R ¹ , R ³ is a hydrogen atom or a methyl group, and x is 1 to 3.)

Description

Adhesive composition and adhesive tape

The present invention relates to a pressure-sensitive adhesive composition that does not cause floating or peeling even under high temperature (for example, 300° C.), and does not generate glue residue or contamination on an adherend even when peeled thereafter, and an adhesive tape using the same. .

In general, an adhesive tape having an acrylic pressure-sensitive adhesive layer exhibits little thermal deterioration in a high-temperature environment, and thus is widely used in industrial applications such as electric/electronic fields. However, in recent years, such an industrial use WHEREIN: An adhesive tape may be exposed under a higher temperature environment. Therefore, it is calculated|required to further improve the heat resistance of an acrylic adhesive. On the other hand, for example, in a heat treatment process, when parts are temporarily fixed with an adhesive tape or when a surface that is easily damaged during processing and transport is protected, the adhesive tape in use has high adhesion to an adherend. It has and can peel easily (re-peelability) is calculated|required by the adhesive tape after use. Accordingly, various techniques have been proposed to improve these points.

Patent Document 1 describes a heat-peelable thermosetting pressure-sensitive adhesive film in which the acrylic pressure-sensitive adhesive layer contains a thermosetting acrylic pressure-sensitive adhesive polymer having an epoxy group and a carboxyl group in the molecule. And, it is described that since a three-dimensional crosslink is rapidly formed and cured between the epoxy group and the carboxyl group by heating, the pressure-sensitive adhesive film can be easily peeled off from the adherend by reducing the adhesiveness. Specifically, it is described that the heating temperature in the Examples was 190°C, which resulted in a very low adhesive force by thermal curing, and could be easily peeled off.

In Patent Document 2, an adhesive component comprising an acrylic adhesive (C1) having a mass average molecular weight of 750,000 or more and an acid value of 5 or more and an acrylic adhesive (C2) having a mass average molecular weight of less than 400,000 and an acid value of 40 or more and a crosslinking agent (D). body is described. In addition, it is explained that the high molecular weight component (C1) is a component that maintains peeling force under heating and high temperature by its cohesive force, and the low molecular weight component (C2) is a component that improves re-peelability by controlling peelability after heating. . The heating temperature is 110°C to 170°C.

In Patent Document 3, the adhesive force to stainless steel after 20 minutes when affixed at 23° C. is 100 mN/inch or less, and after sticking, the adhesive strength after heating at 170° C. for 1 hour is 200 mN/inch or less, does not contain a carboxyl group An acrylic solvent-based pressure-sensitive adhesive composition comprising an acrylic polymer (A) that does not exist is described. And in order to acquire such ultra-fine adhesive force, it is demonstrated that it is important that the acrylic polymer (A) does not have a carboxyl group.

Patent Document 4 describes a pressure-sensitive adhesive composition comprising an acrylic resin, a crosslinking agent for crosslinking the acrylic resin, a photocurable resin, and a photocuring agent for curing the photocurable resin. In addition, this pressure-sensitive adhesive composition has a low initial adhesive force, can be easily attached and corrected, does not float or peel off after bonding to an adherend, and the adhesive strength does not change even when placed in a high-temperature environment. It is also explained that it is possible to reduce the contamination of the glue residue and the adherend. The heating temperature in the examples is 230°C.

Patent Document 5 discloses an acrylic acid ester and/or methacrylic acid ester, a primary hydroxyl group-containing monomer having a primary hydroxyl group in the molecule, a secondary hydroxyl group-containing monomer having a secondary hydroxyl group in the molecule, and/or a tertiary A pressure-sensitive adhesive composition comprising a copolymer polymer in which at least a tertiary hydroxyl group-containing monomer having a hydroxyl group is copolymerized and is crosslinked with a crosslinking agent is described. And, by adding a primary hydroxyl group-containing monomer having a primary hydroxyl group in the molecule, the degree of crosslinking of the pressure-sensitive adhesive composition can be increased and heat resistance and heat-and-moisture resistance can be improved, and 2 having a secondary hydroxyl group in the molecule It is demonstrated that rework property can be ensured by adding a tertiary hydroxyl-containing monomer and/or a tertiary hydroxyl-containing monomer having a tertiary hydroxyl group. The heating temperature in the examples is 80°C.

Moreover, although the objective is different (it aims at providing the low-viscosity adhesive composition excellent in adhesive performance, such as adhesive force and low temperature tack), in Patent Document 6, a hydroxyl group is bonded to an alkyl group having 3 or more carbon atoms. A pressure-sensitive adhesive composition is disclosed in which the hydroxyalkyl (meth)acrylate (a-2-1) and (a-2-1) are used in combination with a hydroxyl group-containing (meth)acrylate in which a hydroxyl group is bonded to a shorter alkyl group.

In recent years, with the development of technology, the temperature of the heating process is gradually increasing, for example, the process of performing heat treatment for a short time under a high temperature of 300°C is starting to increase. On the other hand, the pressure-sensitive adhesive composition or adhesive tape described in Patent Documents 1 to 5 has a heat resistance verification temperature of only 230°C, and a recent demand that both heat resistance and re-peelability are excellent even under a higher temperature (for example, 300°C). cannot be sufficiently satisfied with Moreover, since the adhesive composition of patent document 6 does not aim at the improvement of heat resistance, and uses only a small amount of an isocyanate type hardening|curing agent, it is thought that the heat resistance is not enough.

[Patent Document 1] Japanese Patent Laid-Open No. 2003-238910 [Patent Document 2] Japanese Patent Laid-Open No. 2003-292931 [Patent Document 3] Japanese Patent Laid-Open No. 2004-217740 [Patent Document 4] International Publication No. 2015/119042 [Patent Document 5] Japanese Patent Laid-Open No. 2009-29948 [Patent Document 6] Japanese Patent Laid-Open No. 2014-108968

It is an object of the present invention to have sufficient initial adhesive strength, and at the same time, no lifting or peeling occurs even under high temperature (for example, 300°C), and no glue residue or contamination on the adherend even if peeled off after heating. It is providing an adhesive composition and an adhesive tape using the same.

As a result of earnest examination to achieve the above object, the present inventors found that a composition containing a (meth)acrylic polymer (A) having a specific copolymer composition and an epoxy crosslinking agent (B) is very effective, came to the conclusion of the invention.

That is, the present invention is a monomer unit derived from two or more types of hydroxyl group-containing (meth)acrylate monomers represented by the following formulas (A1) and (A2), and 5.1 to 20% by mass of a carboxyl group-containing monomer (A3). (meth)acrylic polymer (A) containing at least a monomer unit to

(In formulas A1 and A2, R ¹ and R ² are a hydrocarbon group or an oxygen atom-containing hydrocarbon group, the number of carbon atoms in R ² is greater than the number of carbon atoms in R ¹ , R ³ is a hydrogen atom or a methyl group, and x is 1 to 3), and

Epoxy crosslinking agent (B)

It is a pressure-sensitive adhesive composition containing.

Moreover, this invention is an adhesive tape which has the adhesive layer formed from the said adhesive composition.

In the present invention, since the (meth)acrylic polymer (A) having a specific copolymer composition and the epoxy-based crosslinking agent (B) are included, the decomposition temperature of a general acrylic polymer of, for example, 300°C while having sufficient initial adhesive strength It is possible to provide a pressure-sensitive adhesive composition in which no lifting or peeling occurs even under a high temperature far exceeding the above, and no glue residue or contamination on an adherend even when peeled off after heating, and an adhesive tape using the same.

<Adhesive composition>

The adhesive composition of this invention is a composition containing a (meth)acrylic-type polymer (A) and an epoxy-type crosslinking agent (B).

The (meth)acrylic polymer (A) used in the pressure-sensitive adhesive composition is a monomer unit derived from two or more types of hydroxyl group-containing (meth)acrylate monomers represented by the following formulas (A1) and (A2), and a carboxyl group-containing monomer ( At least the monomer unit resulting from A3) is included. In the following description, the hydroxyl group-containing (meth)acrylate monomer represented by the formula (A1) is referred to as a “hydroxyl group-containing short-chain monomer (A1)”, and a hydroxyl group-containing (meth)acrylate monomer represented by the formula (A2) It is called "hydroxyl group-containing long-chain monomer (A2)."

(In formulas A1 and A2, R ¹ and R ² are a hydrocarbon group or an oxygen atom-containing hydrocarbon group, the number of carbon atoms in R ² is greater than the number of carbon atoms in R ¹ , R ³ is a hydrogen atom or a methyl group, and x is 1-3.)

In the prior art, it is common to avoid the use of a functional group-containing monomer as much as possible when it is intended to improve the heat resistance properties of the pressure-sensitive adhesive composition. However, in this invention, the heat resistance excellent in an adhesive composition is provided by using together a hydroxyl-containing short-chain monomer (A1) and a hydroxyl-containing long-chain monomer (A2). Although the reason is not necessarily clear, for example, the monomer unit resulting from the hydroxyl group-containing short-chain monomer (A1) is difficult to thermally decompose, and the monomer unit resulting from the hydroxyl group-containing long-chain monomer (A2) contributes to the improvement of the initial adhesive strength. At the same time, the long chain R ² contributes to the improvement of heat resistance by entanglement, and the crosslinking reaction occurs step by step, so that each of the above-described actions of both is increased to show appropriate adhesive strength even after high-temperature heating. guessed

R ¹ and R ² of the hydroxyl group-containing short-chain monomer (A1) and the hydroxyl group-containing long-chain monomer (A2) may be a hydrocarbon group or an oxygen atom-containing hydrocarbon group, and the type is not particularly limited. Although either saturated or unsaturated may be sufficient, a saturated hydrocarbon group and an oxygen atom containing saturated hydrocarbon group are preferable. Moreover, although either aliphatic or aromatic may be sufficient, an aliphatic hydrocarbon group and an oxygen atom containing aliphatic saturated hydrocarbon group are preferable. In the case of aliphatic, any of linear, branched, and alicyclic may be sufficient, but linear or branched linear or branched aliphatic hydrocarbon group and oxygen atom containing A gaseous aliphatic hydrocarbon group is preferable, and a linear aliphatic hydrocarbon group and an oxygen atom-containing linear aliphatic hydrocarbon group are more preferable.

When R ¹ and R ² of the hydroxyl group-containing short-chain monomer (A1) and the hydroxyl group-containing long-chain monomer (A2) are hydrocarbon groups, -R ¹ -(OH)x and -R ² -(OH)x (that is, a hydrocarbon group having a hydroxyl group) ), hydroxyethyl group, 2-hydroxypropyl group, 3-hydroxypropyl group, 2-hydroxy-1-methylethyl group, 2-hydroxybutyl group, 3-hydroxybutyl group, 4-hydroxy group hydroxybutyl group, 2-hydroxy-1,1-dimethylethyl group, 3-hydroxy-2-methylpropyl group, 2-hydroxy-2-methylpropyl group, 1-(hydroxymethyl)propyl group, 2- Hydroxy-1-methylpropyl group, 3-hydroxy-1-methylpropyl group, 2-hydroxypentyl group, 5-hydroxypentyl group, 2,2-dimethyl-3-hydroxypropyl group, 3-methyl -3-hydroxybutyl group, 2-hydroxyhexyl group, 6-hydroxyhexyl group, 2-hydroxyheptyl group, 7-hydroxyhexyl group, 2-hydroxyoctyl group, 8-hydroxyoctyl group, and an unsaturated aliphatic hydrocarbon group having a hydroxyl group such as a 10-hydroxydecyl group.

When R ¹ and R ² of the hydroxyl group-containing short-chain monomer (A1) and the hydroxyl group-containing long-chain monomer (A2) are an oxygen atom-containing hydrocarbon group, -R ¹ -(OH)x and -R ² -(OH)x (that is, the hydroxyl group Specific examples of the oxygen atom-containing hydrocarbon group having) include a group represented by -(OR)n-OH (for example, a polyalkylene glycol group such as a polyethylene glycol group, a polypropylene glycol group, or a polybutylene glycol group), 2 and an oxygen atom unsaturated aliphatic hydrocarbon group having a hydroxyl group such as a -(2-hydroxyethoxy)ethyl group, a 2-hydroxy-3-methoxypropyl group and a 2-hydroxy-3-butoxypropyl group.

The number of carbon atoms in R ² of the long-chain hydroxyl group-containing monomer (A2) is larger than the number of carbon atoms in R ¹ in the short-chain hydroxyl group-containing monomer (A1). Specifically, the difference between the number of carbon atoms in R ² and the number of carbon atoms in R ¹ is 1 or more, preferably 2 or more, and more preferably 2 or more and 8 or less. In particular, when this difference is 2 or more, a more remarkable effect can be acquired in terms of heat resistance (for example, improvement of adhesive force after heating, and prevention of generation|occurrence|production of a float). It is presumed that this is because the entanglement of molecular chains becomes more sufficient. Therefore, it is preferable that the carbon atom number of R< ² > of a hydroxyl-containing long-chain monomer (A2) is large moderately. However, if too large, the ratio of the amount of hydroxyl groups to the amount of R ² is relatively lowered, so it is not preferable. Specifically, the number of carbon atoms of R ² in the hydroxyl group-containing long-chain monomer (A2) is 2 or more, preferably Preferably it is 3 or more, More preferably, it is 4 or more and 12 or less. The number of carbon atoms of R ¹ of the hydroxyl group-containing short-chain monomer (A1) is 1 or more, preferably 1 or more and 4 or less, and more preferably 2 or more and 3 or less.

Each R ³ of the hydroxyl group-containing short-chain monomer (A1) and the hydroxyl group-containing long-chain monomer (A2) is a hydrogen atom or a methyl group. R ³ of the hydroxyl group-containing short-chain monomer (A1) and R ³ of the hydroxyl group-containing long-chain monomer (A2) may be the same as or different from each other.

In the hydroxyl group-containing short-chain monomer (A1) and the hydroxyl group-containing long-chain monomer (A2), x represents the number of hydroxyl groups -(OH) bonded to R ¹ and R ² . x is 1-3, preferably 1-2, and most preferably 1. x of the hydroxyl group-containing short-chain monomer (A1) and x of the hydroxyl group-containing long-chain monomer (A2) may be the same as or different from each other.

The bonding position of -(OH) to R ¹ and R ² of the hydroxyl group-containing short-chain monomer (A1) and the hydroxyl group-containing long-chain monomer (A2) is not particularly limited. However, regarding the bonding position of -(OH) with respect to R< ² > of a hydroxyl-containing long-chain monomer (A2), the molecular terminal side of R< ² > (the terminal on the far side with respect to the (meth)acryloyl group) is preferable.

Particularly suitable specific examples of the hydroxyl group-containing short-chain monomer (A1) and the hydroxyl group-containing long-chain monomer (A2) include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth ) (meth)acrylic acid hydroxyalkyl esters such as acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; polyethylene glycol mono Polyalkylene glycol monoacrylate, such as an acrylate and a polypropylene glycol monoacrylate; is mentioned. That is, it is preferable to select and use together 2 or more types of monomers from these.

The content of the total of the monomer units resulting from the hydroxyl group-containing short-chain monomer (A1) and the monomer units resulting from the hydroxyl group-containing long-chain monomer (A2) in 100 mass% of the monomer units constituting the (meth)acrylic polymer (A) is preferably Preferably it is 5-20 mass %, More preferably, it is 10-15 mass %. Moreover, it is preferable that there is more content of the monomeric unit resulting from a hydroxyl-containing long-chain monomer (A2) than content of the monomeric unit resulting from a hydroxyl-containing short-chain monomer (A1). Thereby, a more remarkable effect can be acquired at the point of heat resistance (for example, the improvement of adhesive force after heating, and prevention of generation|occurrence|production of a float). Specifically, the mixing ratio (A1/A2) of both monomer units is preferably 49/51 to 30/70, more preferably 45/55 to 35/65.

The carboxyl group-containing monomer (A3) is a component that cross-links and reacts with the epoxy-based cross-linking agent (B) to improve physical properties such as cohesive force, thereby suppressing the glue residue upon re-peeling. A carboxyl group containing monomer (A3) is not specifically limited, What is necessary is just a compound which has a carboxyl group (acidic group) and an unsaturated double bond. Specific examples thereof include acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, grataconic acid, 2-acryloyloxyethyl succinic acid, 2-acryloyloxyethyl phthalic acid, ω-carboxypolycaprolactone (repeating unit (n) = about 2) monoacrylate (for example, Toakosei Co., Ltd., trade name M-5300), phthalic acid monohydroxyethyl acrylate (for example, Toakosei Co., Ltd.; trade name M-5400) and an acrylic acid dimer (for example, the Toakosei company make, trade name M-5600) are mentioned. You may use together 2 or more types of carboxyl group containing monomers (A3). Especially, a (meth)acrylic-type monomer (namely, the monomer which has a (meth)acryloyl group) is preferable, and especially acrylic acid and methacrylic acid are more preferable.

The content of the monomer unit resulting from the carboxyl group-containing monomer (A3) in 100 mass% of the monomer units constituting the (meth)acrylic polymer (A) is 5.1 to 20 mass% or less, preferably 7 to 18 mass%, More preferably, it is 9-16 mass %.

The (meth)acrylic polymer (A) may contain the monomer unit resulting from other monomers other than each monomer demonstrated above. As another monomer, the (meth)acrylate monomer which does not contain a hydroxyl group or a carboxyl group is preferable, an alkyl (meth)acrylate monomer is more preferable, The alkyl (meth)acrylate monomer which has a C1-C12 alkyl group. is particularly preferred. As specific examples, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, 2-ethylhexyl (meth) acrylate , 2-methylbutyl (meth) acrylate, isoamyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, dodecyl (meth) ) alkyl (meth) acrylate having an alkyl group having 1 to 12 carbon atoms such as acrylate; phenoxyethyl (meth) acrylate; tetrahydrofurfuryl (meth) acrylate; alkoxyalkyl (meth) acrylate. can Moreover, you can also use together desired monomers other than a (meth)acrylate monomer.

Among 100% by mass of the monomer units constituting the (meth)acrylic polymer (A), a (meth)acrylate monomer (more preferably an alkyl (meth)acrylate monomer) that does not contain a hydroxyl group or a carboxyl group. Content becomes like this. Preferably it is 60-90 mass %, More preferably, it is 70-85 mass %.

The (meth)acrylic polymer (A) can be obtained by copolymerizing each component described above. The polymerization method is not particularly limited, and various known methods can be used, but radical solution polymerization is particularly preferable. Radical solution polymerization is generally carried out in a nitrogen atmosphere using an azo compound or a peroxide-based polymerization initiator. The polymerization temperature is usually about 60 to 80°C, and the polymerization time is usually about 5 to 10 hours.

The epoxy-type crosslinking agent (B) used for an adhesive composition is a component which improves the cohesive force of an adhesive composition by crosslinking-reacting with the carboxyl group and/or hydroxyl group of a (meth)acrylic-type polymer (A). Furthermore, in the present invention, the epoxy-based crosslinking agent (B) also greatly contributes to the improvement of heat resistance. Although the reason is not necessarily clear, for example, even if the (meth)acrylic polymer (A) contains a large number of functional groups such as carboxyl groups and hydroxyl groups, the portion that is prone to thermal decomposition in the molecule is capped with an epoxy-based crosslinking agent (B) ( cap), and it is estimated that it is because it becomes difficult to thermally decompose. According to the knowledge of the present inventors, if a crosslinking agent (specifically, an isocyanate-based crosslinking agent) other than the epoxy-based crosslinking agent (B) is used, the pressure-sensitive adhesive composition tends to gel before coating, making it difficult to apply to a substrate .

Specific examples of the epoxy-based crosslinking agent (B) include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, and 1,6-hexanediol diglycidyl ether. , trimethylolpropane triglycidyl ether, diglycidyl aniline, N,N,N',N'-tetraglycidyl-m-xylenediamine, 1,3-bis(N,N'-diglycy dilaminomethyl) cyclohexane. You may use together 2 or more types of epoxy-type crosslinking agents (B).

To [ content of an epoxy-type crosslinking agent (B) / 100 mass parts of (meth)acrylic-type polymer (A)), Preferably it is 5-25 mass parts, More preferably, it is 7-18 mass parts, Especially preferably, 8-15 mass parts is wealth

Moreover, the adhesive composition may contain arbitrary resin components other than a (meth)acrylic-type polymer (A) in the range which does not impair the effect of this invention. Moreover, you may contain other additive components as needed. Specific examples of the additive component include a solvent, antioxidant, ultraviolet absorber, light stabilizer, antistatic agent, filler, and pigment.

<Adhesive tape>

The adhesive tape of this invention has the adhesive layer formed with the adhesive composition of this invention demonstrated above. Typically, an adhesive tape has a base material and an adhesive layer on at least one surface of this base material. However, the adhesive tape of the present invention is not limited thereto, and may be, for example, a baseless type adhesive tape having no substrate.

The thickness of the adhesive layer in the adhesive tape which has a base material becomes like this. Preferably it is 2-100 micrometers, More preferably, it is 3-80 micrometers, Especially preferably, it is 4-70 micrometers. The thickness of the adhesive layer in the adhesive tape of a baseless type is also the same.

The adhesive layer in an adhesive tape can be formed by crosslinking-reacting the adhesive composition of this invention. For example, the pressure-sensitive adhesive composition may be applied on a substrate and cross-linked by heating to form an adhesive layer on the substrate. Moreover, an adhesive composition may be apply|coated on a release paper or another film, it is crosslinked by heating, and an adhesive layer is formed, and this adhesive layer can also be bonded together on the single side|surface or both surfaces of a base material. Coating apparatuses, such as a roll coater, a die coater, and a lip coater, can be used for application|coating of an adhesive composition, for example. When heating after application|coating, the solvent in an adhesive composition can also be removed with crosslinking reaction by heating.

The type of the substrate used for the adhesive tape is not particularly limited, and may be appropriately selected depending on the performance (heat resistance, etc.) required at the time of use. For example, when the operating temperature of an adhesive tape is less than 150 degreeC, you may use well-known resin base materials, such as a polyethylene terephthalate (PET). When the operating temperature of the adhesive tape is 150° C. or higher, a resin substrate having excellent heat resistance is preferable, and specifically, a resin selected from the group consisting of polyphenylene sulfide, polyetherimide, polyetheretherketone and polyimide. The substrate being constituted is preferred. Especially, the base material comprised from polyimide is especially preferable. The thickness of the substrate is preferably 12.5 to 125 µm, more preferably 17.5 to 50 µm. An adhesive layer may be provided only on the single side|surface of a base material, and it is good also as a double-sided adhesive tape by forming in both surfaces.

It is preferable that the adhesive tape of this invention has moderate adhesive force at the time of re-peeling after heating. This can be specified by the adhesive force of the adhesive tape after heating at 300 degreeC for 2 hours, for example. Specifically, the adhesive strength of the adhesive tape according to JIS Z 0237 (2000) after heating the adhesive tape pasted to the SUS plate at 300° C. for 2 hours, and then leaving it to stand at room temperature (23° C.) for 2 hours, is preferably 0.03-1.5 N/10mm, More preferably, it is 0.05-1.0 N/10mm, Especially preferably, it is 0.1-0.4N/10mm. Details of measurement conditions are described in the column of Examples.

Example

Hereinafter, the present invention will be described in more detail by way of Examples. However, the present invention is not limited to these examples. In the following description, "part" means "part by mass".

<Examples 1-8 and Comparative Examples 1-2>

[Preparation of (meth)acrylic polymer (A)]

Each monomer was put into a solvent at the compounding ratio (mass %) shown in Table 1, and a polymerization initiator (manufactured by Wako Pure Chemical Industries, Ltd., trade name V-59) composed of 2,2'-azobis(2-methylbutyronitrile) was added. 0.2 parts were added with respect to 100 parts of monomers in total, and it heated at 70 degreeC in nitrogen atmosphere, then it heated at 90 degreeC, and obtained the (meth)acrylic-type polymer (A) solution of 30% of solid content.

[Preparation of adhesive composition and adhesive tape]

The obtained (meth)acrylic polymer (A) solution is diluted, and an epoxy-based crosslinking agent (manufactured by Soken Chemical Co., Ltd., trade name E-5 XM) comprising glycerin diglycidyl ether is added to 100 parts of (meth)acrylic polymer (A) 10 parts was added with respect to this, and the adhesive composition was obtained. This adhesive composition was apply|coated on the polyimide base material with a thickness of 25 micrometers so that the thickness after drying might become the thickness of Table 1 base material. Then, it heat-dried, the solvent was removed, and the adhesive tape was obtained.

<Evaluation test>

The following methods evaluated the adhesive tapes obtained in Examples 1-8 and Comparative Examples 1-2. A result is shown in Table 1.

(Initial Adhesion)

According to JIS Z 0237 (2000), the adhesive force to the SUS plate was measured.

(Adhesive strength after heating to 300℃)

The adhesive tape was cut to 10 mm width to obtain a test piece. This test piece was bonded to the SUS board, and it left still in 300 degreeC oven for 2 hours, and left it to stand at room temperature (23 degreeC) after that for 2 hours. And according to JISZ0237(2000) (adhesive tape/adhesive sheet test method), the adhesive force was measured on the conditions of 180 degree|times peeling angle and the peeling speed|rate of 300 mm/min.

(Floating and peeling off after heating to 300°C)

In the above-mentioned 300 degreeC post-heating adhesive force test, after heating an adhesive tape, the presence or absence of floating|lifting and peeling of an adhesive tape was visually confirmed, and the following criteria evaluated it.

"(circle)": The float and peeling did not generate|occur|produce.

"x": floatation and/or peeling generate|occur|produced.

(Grass residue and contamination after heating to 300°C)

In the above-described adhesive strength test after heating at 300°C, when the adhesive tape after heating was peeled off, the presence or absence of glue residues and contamination on the SUS plate was visually confirmed and evaluated according to the following criteria.

"(circle)": A grass residue and contamination did not generate|occur|produce.

"X": A glue residue and/or contamination generate|occur|produced.

The abbreviations in Table 1 are as follows.

"HEA": 2-hydroxyethyl acrylate

"4-HBA": 4-hydroxybutyl acrylate

"AE-200": Polyethylene glycol monoacrylate (Nippon Corporation make, Blendmer (registered trademark) AE-200)

"AA": acrylic acid

"2-EHA": 2-ethylhexyl acrylate

"MA": methyl acrylate

<Evaluation>

As is clear from Table 1, the adhesive tapes of Examples 1 to 8 had an appropriate value for adhesive strength after heating at 300°C, and neither floatation nor peeling after heating at 300°C, paste residue, or contamination occurred. Therefore, it can be understood that these adhesive tapes are excellent in heat resistance and also excellent in re-peelability after heating.

The adhesive tapes of Examples 1-3 are the same adhesive tapes except that the thickness of an adhesive layer differs. Since the adhesive tape of Example 2 had a thick adhesive layer, the initial adhesive force was very high compared to other Examples (Examples 1 and 3). However, the adhesive strength after heating at 300° C. was at the same level as in the other examples. Although the adhesive layer of the adhesive tape of Example 3 was slightly thin, the adhesive force after 300 degreeC heating was the level equivalent to another Example. From these results, it can be understood that the thickness of the pressure-sensitive adhesive layer hardly affects the adhesive strength after heating at 300°C.

The adhesive tapes of Examples 4-6 are adhesive tapes which increased the quantity of each monomer other than 2-EHA. Since the adhesive tapes of Examples 4-6 had a large amount of a monomer with a comparatively high Tg, the initial adhesive force was lower than Example 1. However, the adhesive strength after heating at 300° C. was at a level without a problem. From these results, it can be understood that the increase in the amount of the monomer having a relatively high Tg does not significantly affect the adhesive strength after heating at 300°C.

The adhesive tape of Comparative Example 1 was an adhesive tape using only one type of long-chain monomer (4-HBA) as a hydroxyl group-containing (meth)acrylate monomer, and the adhesive strength after heating at 300° C. was too low, and floatation occurred after heating. This is presumed to be the result of insufficient entanglement of molecular chains and easy thermal decomposition when only one type of long-chain monomer (4-HBA) is used.

The adhesive tape of the comparative example 2 is an adhesive tape with too little content of a carboxyl group containing monomer (A3), and the paste residue generate|occur|produced at the time of peeling after heating. It is presumed that this is a result of the low crosslinking density, and thus the strength of the crosslinked structure is lowered.

The pressure-sensitive adhesive composition of the present invention and the pressure-sensitive adhesive tape using the same are excellent in initial adhesive strength and at the same time have heat resistance and re-peelability that can be used even under a high temperature of 300°C, so they are useful for all uses requiring these properties. For example, it can be suitably used for the manufacturing process which requires the heat processing process under high temperature, such as a component built-in board|substrate, a glass substrate, a sensor, and a semiconductor.

Claims (7)

A monomer unit resulting from two or more types of hydroxyl group-containing (meth)acrylate monomers represented by the following formulas (A1) and (A2), and a monomer unit resulting from a carboxyl group-containing monomer (A3) of 5.1 to 20 mass% at least Containing (meth)acrylic polymer (A)

(In formulas A1 and A2, R ¹ and R ² are a hydrocarbon group or an oxygen atom-containing hydrocarbon group, the number of carbon atoms in R ² is greater than the number of carbon atoms in R ¹ , R ³ is a hydrogen atom or a methyl group, and x is 1 to 3), and
Epoxy crosslinking agent (B)
A pressure-sensitive adhesive composition containing. The method according to claim 1,
The adhesive composition containing 5-25 mass parts of epoxy-type crosslinking agents (B) with respect to 100 mass parts of (meth)acrylic-type polymers (A). An adhesive tape having a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition of claim 1. 4. The method of claim 3,
The adhesive tape which has a base material and an adhesive layer on at least one surface of the base material. 5. The method according to claim 4,
An adhesive tape wherein the substrate is made of a resin selected from the group consisting of polyphenylene sulfide, polyetherimide, polyetheretherketone and polyimide. 4. The method of claim 3,
An adhesive tape having a thickness of 2 to 100 µm of an adhesive layer. 4. The method of claim 3,
The adhesive strength of the adhesive tape according to JIS Z 0237 (2000) after heating the adhesive tape bonded to the SUS board at 300 degreeC for 2 hours and leaving it to stand at room temperature for 2 hours after that is 0.03-1.5 N/10mm adhesive tape.