TW201800523A - Adhesive composition and adhesive tape - Google Patents

Abstract

Disclosed are: an adhesive composition and an adhesive tape produced by using the same, in which the adhesive composition contains a (meth)acrylic polymer (A) comprising two or more kinds of hydroxyl group-containing (meth) acrylate monomer units represented by the following formulas (A1) and (A2), wherein, R1 and R2 are hydrocarbon groups or oxygen atom-containing hydrocarbon groups, the number of carbon atoms of R2 is more than the number of carbon atoms of R1, R3 is hydrogen atom or methyl group, and x is 1~3, and, 5.1~20% by mass of a carboxyl group-containing monomer unit (A3); and an epoxy based crosslinking agent (B).

Description

Adhesive composition and adhesive tape

The present invention relates to an adhesive composition which does not float or peel off at a high temperature (for example, 300 ° C), and which does not cause residual glue or contamination even after peeling off the adherend, and an adhesive tape using the same .

Generally, an adhesive tape having an acrylic adhesive layer is used because it has less thermal deterioration in a high-temperature environment, and thus is used in industrial applications such as electric ‧ electronics. However, in recent years, such industrial uses have exposed the adhesive tape to a higher temperature environment. Therefore, it is expected to further improve the heat resistance of the acrylic adhesive. On the other hand, for example, in the case of the heat treatment step, when the component is temporarily fixed by the adhesive tape or the surface which is easily scratched during processing/transporting, the adhesive tape in use is required to have a high adhesion to the adherend. The force and the adhesive tape after use can be easily peeled off (repeelability). Therefore, various proposals have been made for the improvement of these matters.

The heat-peelable thermosetting adhesive film described in Patent Document 1 is a thermosetting acrylic-based adhesive polymer having an epoxy group and a carboxyl group in the molecule in the acrylic pressure-sensitive adhesive layer. In addition, since the adhesion between the epoxy group and the carboxyl group is rapidly formed by heating and hardening, the adhesiveness of the adhesive film is lowered, and the peeling of the adhesive film may be easily caused. Specifically, the heating temperature of the example is 190 ° C, which is extremely low in adhesion due to thermal curing, and can be easily peeled off.

The adhesive described in Patent Document 2 is a reaction product of an adhesive component and a crosslinking agent (D), and the adhesive component is an acrylic adhesive having a mass average molecular weight of 750,000 or more and an acid value of 5 or more (C1). And an acrylic adhesive (C2) having a mass average molecular weight of less than 400,000 and an acid value of 40 or more. In addition, the high molecular weight component (C1) is a component that maintains the peeling force at a high temperature by the cohesive force, and the low molecular weight component (C2) is a component that controls the releasability after heating to improve the removability. The heating temperature is 110 ° C ~ 170 ° C.

The acrylic solvent-based adhesive composition described in Patent Document 3 is adhered at 23 ° C, and after 20 minutes, the adhesion to stainless steel is less than 100 mN/吋, and after adhesion, the adhesive is heated at 170 ° C for 1 hour. The force is 200 mN/吋 or less, and the acrylic polymer (A) containing no carboxyl group is contained. Further, it has been described that in order to obtain such ultra-adhesive force, it is important that the acrylic polymer (A) does not have a carboxyl group.

The adhesive composition described in Patent Document 4 contains an acrylic resin, a crosslinking agent for crosslinking the acrylic resin, a photocurable resin, and a light curing agent for curing the photocurable resin. . Moreover, it is explained that the initial adhesive force of the adhesive composition is low, and it can be easily reattached, and it does not float or peel off after being adhered to the adherend, and the adhesive force is placed even in a high temperature environment. There will still be no changes, and the residual glue or the contaminated material may be reduced. The heating temperature of the examples was 230 °C.

The adhesive composition described in Patent Document 5 contains at least an acrylate and/or methacrylate, a primary hydroxyl group-containing monomer having a primary hydroxyl group in the molecule, and a secondary hydroxyl group having a secondary hydroxyl group in the molecule. A copolymerized polymer obtained by crosslinking a body and/or a tertiary hydroxyl group-containing monomer having a tertiary hydroxyl group and crosslinking with a crosslinking agent. Further, there is a description of the first-order hydroxyl group having a primary hydroxyl group by adding a molecule The body can improve the degree of crosslinking of the adhesive composition, can improve heat resistance and heat and humidity resistance, and by adding a secondary hydroxyl group-containing monomer having a secondary hydroxyl group in the molecule and/or having a tertiary hydroxyl group Grade hydroxy monomer ensures reworkability. The heating temperature of the examples was 80 °C.

Further, although it is a different purpose (the purpose is to provide a low-viscosity adhesive composition having excellent adhesion properties such as adhesion and low-temperature adhesion), the adhesive composition described in Patent Document 6 is used in combination: three or more carbon atoms. a hydroxyalkyl (meth) acrylate (a-2-1) having a hydroxyl group bonded to an alkyl group, and a hydroxyl group bonded to a hydroxyl group on a shorter alkyl group (a-2-1) (Meth) acrylate.

In recent years, as the technology has progressed, the temperature of the heating step has also increased. For example, there has been a step of increasing the heat treatment at a high temperature of 300 ° C for a short time. On the other hand, in the adhesive composition or the adhesive tape described in Patent Documents 1 to 5, the heat-resistant verification temperature is preferably only 230 ° C, and even in recent years, even at a higher temperature (for example, 300 ° C). Under the circumstance, both the heat resistance and the re-peelability are still excellent requirements and cannot be sufficiently satisfied. Further, the adhesive composition described in Patent Document 6 is not intended to improve heat resistance, and only a small amount of an isocyanate-based curing agent is used. Therefore, it is judged that heat resistance is insufficient.

[Previous Technical Literature] [Patent Literature]

Patent Document 1: Japanese Patent Laid-Open Publication No. 2003-238910

Patent Document 2: Japanese Patent Laid-Open Publication No. 2003-292931

Patent Document 3: Japanese Patent Laid-Open Publication No. 2004-217740

Patent Document 4: International Publication No. 2015/119042

Patent Document 5: Japanese Patent Laid-Open Publication No. 2009-29948

Patent Document 6: Japanese Patent Laid-Open Publication No. 2014-108968

The object of the present invention is to provide a sufficient initial adhesion, and even if it is not exposed to high temperature (for example, 300 ° C), it does not float or peel off, and even if it is peeled off after heating, no residual glue or contamination occurs on the adherend. Adhesive composition in the case, and an adhesive tape using the same.

The present inventors have intensively studied in order to achieve the above object, and as a result, it has been found that a composition containing a (meth)acrylic polymer (A) having a specific copolymerization composition and an epoxy crosslinking agent (B) is very effective. The present invention has been completed.

In other words, the adhesive composition of the present invention contains (meth)acrylic polymer (A) containing at least two or more hydroxyl groups represented by the following formulas (A1) and (A2) ( a monomer unit derived from a methyl acrylate monomer, and a monomer unit derived from a carboxyl group-containing monomer (A3): 5.1 to 20% by mass;

(In the formulae A1 and A2, R ¹ and R ² are a hydrocarbon group or a hydrocarbon group containing an oxygen atom; R ^{2 has} a larger number of carbon atoms than R ¹ ; R ³ is a hydrogen atom or a methyl group; x is a group 1~ 3); and an epoxy crosslinking agent (B).

Furthermore, the adhesive tape of the present invention has an adhesive layer formed of the above-described adhesive composition.

Since the present invention contains a (meth)acrylic polymer (A) having a specific copolymerization composition and an epoxy crosslinking agent (B), it can provide sufficient initial adhesion, even at a distance of, for example, 300 ° C. When the temperature exceeds the decomposition temperature of the general acrylic polymer, the adhesive composition does not float or peel off, and even if it is peeled off after heating, the adhesive composition does not cause residual glue or contamination on the adherend and the adhesion thereof is used. band.

<Adhesive Composition>

The adhesive composition of the present invention contains a composition of a (meth)acrylic polymer (A) and an epoxy crosslinking agent (B).

The (meth)acrylic polymer (A) used in the adhesive composition contains at least two kinds of hydroxyl group-containing (meth) acrylate monomers represented by the following formulas (A1) and (A2). a monomer unit derived, and a monomer unit derived from a carboxyl group-containing monomer (A3). In the following description, the hydroxyl group-containing (meth) acrylate monomer represented by the formula (A1) is referred to as "hydroxy group-containing short-chain monomer (A1)", and the hydroxyl group-containing (methyl group) represented by the formula (A2) The acrylate monomer is referred to as "hydroxyl-containing long-chain monomer (A2)".

[Chemical 2]

(In the formulae A1 and A2, R ¹ and R ² are a hydrocarbon group or a hydrocarbon group containing an oxygen atom; R ^{2 has} a larger number of carbon atoms than R ¹ ; R ³ is a hydrogen atom or a methyl group; x is a group 1~ 3.)

When the prior art is intended to enhance the heat resistance characteristics of the adhesive composition, it is generally preferred to avoid the use of a monomer having a functional group as much as possible. However, the present invention imparts excellent heat resistance to the adhesive composition by using a short-chain monomer (A1) having a hydroxyl group and a long-chain monomer (A2) having a hydroxyl group in combination. Although the reason is not clear, for example, the following reason can be presumed: the monomer unit derived from the hydroxyl group-containing short-chain monomer (A1) is not easily thermally decomposed; the monomer derived from the hydroxyl group-containing long-chain monomer (A2) The unit helps to improve the initial adhesion, and the entanglement of the long-chain R ² also contributes to the improvement of heat resistance; and the phase-induced initiation of the crosslinking reaction, by the above-mentioned respective effects of multiplication, even after high temperature heating Can still be caused by moderate adhesion and other reasons.

R ¹ and R ² of the hydroxyl group-containing short-chain monomer (A1) and the hydroxyl group-containing long-chain monomer (A2) are not particularly limited as long as they are a hydrocarbon group or a hydrocarbon group containing an oxygen atom. Both saturated and unsaturated may be used, but it is preferably a saturated hydrocarbon group and a saturated hydrocarbon group containing an oxygen atom. Further, it may be aliphatic or aromatic, but is preferably an aliphatic hydrocarbon group and an aliphatic saturated hydrocarbon group containing an oxygen atom. Further, in the case of an aliphatic group, it may be linear, branched or alicyclic, but is preferably a linear or branched aliphatic hydrocarbon group and a linear or branched oxygen atom. The aliphatic hydrocarbon group is more preferably a linear aliphatic hydrocarbon group and a linear aliphatic hydrocarbon group having an oxygen atom.

When the hydroxyl group-containing short-chain monomer (A1) and the hydroxyl group-containing long-chain monomer (A2) are R ¹ and R ² -based hydrocarbon groups, -R ¹ -(OH)x and -R ² -(OH)x ( Specific examples of the hydrocarbon group having a hydroxyl group include, for example, hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl, 2-hydroxy-1-methylethyl, 2-hydroxybutyl, 3- Hydroxybutyl, 4-hydroxybutyl, 2-hydroxy-1,1-dimethylethyl, 3-hydroxy-2-methylpropyl, 2-hydroxy-2-methylpropyl, 1-(hydroxy Methyl)propyl, 2-hydroxy-1-methylpropyl, 3-hydroxy-1-methylpropyl, 2-hydroxypentyl, 5-hydroxypentyl, 2,2-dimethyl-3- Hydroxypropyl, 3-methyl-3-hydroxybutyl, 2-hydroxyhexyl, 6-hydroxyhexyl, 2-hydroxyheptyl, 7-hydroxyhexyl, 2-hydroxyoctyl, 8-hydroxyoctyl, 10- A hydroxyl group-containing unsaturated aliphatic hydrocarbon group such as a hydroxymethyl 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 a hydrocarbon group having an oxygen atom, -R ¹ -(OH)x and -R ² -( Specific examples of OH)x (i.e., a hydrocarbon group having a hydroxyl group having a hydroxyl group) include, for example, a group represented by -(OR)n-OH (for example, a polyethylene glycol group, a polypropylene glycol group, or a polybutylene glycol group). Oxygen atom with hydroxyl group, such as polyalkylene glycol), 2-(2-hydroxyethoxy)ethyl, 2-hydroxy-3-methoxypropyl, 2-hydroxy-3-butoxypropyl Unsaturated aliphatic hydrocarbon group.

The number of R ² carbon atoms of the hydroxyl group-containing long-chain monomer (A2) is more than the number of R ¹ carbon atoms of the hydroxyl group-containing short-chain monomer (A1). Specifically, the difference between the number of R ² carbon atoms and the number of R ¹ carbon atoms is 1 or more, preferably 2 or more, more preferably 2 or more and 8 or less. In particular, if the difference is 2 or more, a more remarkable effect can be obtained from the viewpoint of heat resistance (for example, an increase in adhesion after heating and prevention of occurrence of floating). The reason can be presumed to be due to the entanglement of molecular chains. Therefore, the hydroxyl group-containing long-chain monomer (A2) preferably has a relatively large number of R ² carbon atoms. However, if it is too large, since the ratio of the amount of hydroxyl groups to the amount of R ² is relatively low, it is preferably avoided. Specifically, the hydroxyl group-containing long-chain monomer (A2) has 2 or more R ² carbon atoms, preferably 3 or more, more preferably 4 or more and 12 or less. The hydroxyl group-containing short-chain monomer (A1) has an R ¹ carbon number of 1 or more, preferably 1 or more and 4 or less, more preferably 2 or more and 3 or less.

Each R ³ -based hydrogen atom or methyl group of the hydroxyl group-containing short-chain monomer (A1) and the hydroxyl group-containing long-chain monomer (A2). R short-chain hydroxyl-containing monomer (A1) ³ long-chain monomer (A2) containing hydroxyl groups in R ³ may be the same line with each other, may also be mutually different.

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

- (OH) The bonding position of 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, the bonding position of R ² of the hydroxyl group-containing long-chain monomer (A2) is preferably the molecular terminal side of R ² (the end of one side away from the (meth) acrylonitrile group). .

Particularly preferred examples of the hydroxyl group-containing short-chain monomer (A1) and the hydroxyl group-containing long-chain monomer (A2) include, for example, 2-hydroxyethyl (meth)acrylate and (meth)acrylic acid. 2-hydroxypropyl ester, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, (meth)acrylic acid-4- A hydroxyalkyl (meth) acrylate such as hydroxybutyl ester; a polyalkylene glycol monoacrylate such as polyethylene glycol monoacrylate or polypropylene glycol monoacrylate; and the like. That is, it is preferable to select two or more types of monomers from these among them.

100% by mass of the monomer unit constituting the (meth)acrylic polymer (A), a monomer unit derived from a hydroxyl group-containing short-chain monomer (A1) and a long-chain monomer having a hydroxyl group (A2) The total content of the monomer units to be derived is preferably 5 to 20% by mass, more preferably 10 to 15% by mass. Further, the content of the monomer unit derived from the hydroxyl group-containing long-chain monomer (A2) is preferably larger than the content of the monomer unit derived from the hydroxyl group-containing short-chain monomer (A1). This phenomenon is heat-resistant (for example, improving the adhesion after heating, preventing floating The occurrence of the viewpoint will have a more significant effect. Specifically, the blend ratio (A1/A2) of the two 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 which causes a crosslinking reaction with the epoxy-based crosslinking agent (B) to enhance physical properties such as cohesive force, whereby the residual rubber at the time of re-peeling can be suppressed. The carboxyl group-containing monomer (A3) is not particularly limited as long as it has a compound having a carboxyl group (acid group) and an unsaturated double bond. Specific examples include acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, glutaconic acid, and succinic acid-2-propene oxide. Ester, phthalic acid-2-propenyloxyethyl ester, ω-carboxypolycaprolactone (repeating unit (n)=about 2) monoacrylate (for example, manufactured by Toagosei Co., Ltd., trade name M-5300), tannic acid single Hydroxyethyl acrylate (for example, manufactured by Toagosei Co., Ltd., trade name: M-5400), acrylic acid dimer (for example, manufactured by Toagosei Co., Ltd., trade name: M-5600). Two or more kinds of carboxyl group-containing monomers (A3) may also be used in combination. Among them, a (meth)acrylic monomer (i.e., a monomer having a (meth)acrylonitrile group), more preferably acrylic acid or methacrylic acid is preferred.

In 100% by mass of the monomer unit constituting the (meth)acrylic polymer (A), the content of the monomer unit derived from the carboxyl group-containing monomer (A3) is 5.1 to 20% by mass or less, preferably 7 ~18% by mass, more preferably 9 to 16% by mass.

The (meth)acrylic polymer (A) may further contain a monomer unit derived from a monomer other than the monomers described above. The other monomer is preferably a (meth) acrylate monomer which does not contain a hydroxyl group or a carboxyl group, more preferably an alkyl (meth) acrylate monomer, and particularly preferably has an alkyl group having 1 to 12 carbon atoms. Alkyl (meth)acrylate monomer. Specific examples thereof include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, and isobutyl (meth)acrylate, ( 2-ethylhexyl methacrylate, 2-methylbutyl (meth) acrylate, isoamyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (methyl) ) n-octyl acrylate, (meth) propylene (alkyl)alkyl (meth)acrylate having an alkyl group having 1 to 12 carbon atoms such as isooctyl acid or dodecyl (meth)acrylate; phenoxyethyl (meth)acrylate; ) tetrahydrofurfuryl acrylate; alkoxyalkyl (meth) acrylate and the like. Further, a desired monomer other than the (meth) acrylate monomer may be used in combination.

100% by mass of the monomer unit constituting the (meth)acrylic polymer (A), a (meth) acrylate monomer having no hydroxyl group or carboxyl group (more preferably, an alkyl (meth) acrylate monomer The content of the monomer unit to be derived is preferably 60 to 90% by mass, more preferably 70 to 85% by 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, and particularly preferred is a radical solution polymerization. The radical solution polymerization is generally carried out under a nitrogen atmosphere using a polymerization initiator based on an azo compound or a peroxide. The polymerization temperature is usually about 60 to 80 ° C, and the polymerization time is usually about 5 to 10 hours.

The epoxy-based crosslinking agent (B) used in the adhesive composition enhances the cohesive force of the adhesive composition by causing a crosslinking reaction with a carboxyl group and/or a hydroxyl group of the (meth)acryl-based polymer (A). Ingredients. Further, in the present invention, the epoxy-based crosslinking agent (B) also contributes greatly to the improvement in heat resistance. Though the reason is not necessarily clear, for example, even if the (meth)acrylic polymer (A) contains a large amount of a functional group such as a carboxyl group or a hydroxyl group, the part which is easily thermally decomposed in the molecule is an epoxy-based crosslinking agent ( B) is covered and thus is not easily thermally decomposed. According to the findings of the inventors of the present invention, when a crosslinking agent other than the epoxy crosslinking agent (B) (specifically, an isocyanate crosslinking agent) is used, the adhesive composition tends to be gelled before coating. Difficult to apply to the substrate.

Specific examples of the epoxy-based crosslinking agent (B) include, for example, ethylene glycol bicyclo Oxypropyl ether, polyethylene glycol diglycidyl ether, glycerol diglycidyl ether, glycerol triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triepoxy Ether, diepoxypropyl aniline, N, N, N', N'-tetraepoxypropyl m-xylylenediamine, 1,3-bis(N,N'-diglycidylaminomethyl) ring Hexane, etc. Two or more epoxy crosslinking agents (B) may also be used in combination.

The content of the epoxy-based crosslinking agent (B) is preferably 5 to 25 parts by mass, more preferably 7 to 18 parts by mass, based on 100 parts by mass of the (meth)acryl-based polymer (A). 8 to 15 parts by mass.

In addition, the adhesive composition may contain any resin component other than the (meth)acrylic polymer (A) insofar as it does not impair the effects of the present invention. Further, other added components may be contained as needed. Specific examples of the component to be added include a solvent, an antioxidant, an ultraviolet absorber, a light stabilizer, an antistatic agent, a filler, and a pigment.

<adhesive tape>

The adhesive tape of the present invention is provided with an adhesive layer formed using the adhesive composition of the present invention described above. A representative adhesive tape is provided with a substrate and an adhesive layer disposed on at least one of the substrates. However, the adhesive tape of the present invention is not limited thereto, and may be, for example, a baseless adhesive tape which is not provided with a substrate.

In the adhesive tape provided with the substrate, the thickness of the adhesive layer is preferably 2 to 100 μm, more preferably 3 to 80 μm, and particularly preferably 4 to 70 μm. The thickness of the adhesive layer of the non-base adhesive tape is also the same.

The adhesive layer of the adhesive tape can be formed by subjecting the adhesive composition of the present invention to a crosslinking reaction. For example, an adhesive composition can be formed on a substrate by applying an adhesive composition onto a substrate and causing a crosslinking reaction by heating. Also, The adhesive composition is applied onto a release paper or other film, and a cross-linking reaction is formed by heating to form an adhesive layer, and the adhesive layer is bonded to one or both sides of the substrate. When the adhesive composition is applied, for example, a coating device such as a roll coater, a die coater, or a lip coater can be used. When heating is applied after coating, the solvent in the adhesive composition can be removed while the crosslinking reaction is carried out by heating.

The type of the substrate to be used for the adhesive tape is not particularly limited, and may be appropriately selected as long as it is used in combination with the required properties (heat resistance, etc.). For example, when the use temperature of the adhesive tape is less than 150 ° C, a known resin substrate such as polyethylene terephthalate (PET) can also be used. When the adhesive tape is used at a temperature of 150 ° C or higher, it is preferably a resin substrate excellent in heat resistance, and particularly preferably from polyphenylene sulfide, polyether oxime, polyether ether ketone, and polyimide. A substrate composed of a resin selected in the group. Among them, a substrate composed of polyimine is more preferable. The thickness of the substrate is preferably 12.5 to 125 μm, more preferably 17.5 to 50 μm. The adhesive layer may be formed only on one side of the substrate or may be formed on both sides to form a double-sided adhesive tape.

The adhesive tape of the present invention preferably has a moderate adhesive force upon re-peeling after heating. This system can be specified by, for example, an adhesive tape adhesion after heating at 300 ° C for 2 hours. Specifically, the adhesive tape to which the SUS plate has been attached is heated at 300 ° C for 2 hours, and then left at room temperature (23 ° C) for 2 hours, and the adhesive tape adhesion according to JIS Z 0237 (2000) is preferably 0.03 to 1.5. N/10mm, more preferably 0.05~1.0N/10mm, especially good 0.1~0.4N/10mm. The details of the measurement conditions are described in the examples.

[Examples]

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

<Examples 1 to 8 and Comparative Examples 1 to 2> [Preparation of (meth)acrylic polymer (A)]

Each monomer was put into a solvent according to the blending ratio (% by mass) shown in Table 1, and a polymerization consisting of 2,2'-azobis(2-methylbutyronitrile) was added to 100 parts of the total of the monomers. 0.2 part of a starter (manufactured by Wako Pure Chemical Industries, Ltd., trade name V-59), heated at 70 ° C under a nitrogen atmosphere, and then heated at 90 ° C to obtain a 30% solid (meth)acrylic polymer (A) solution.

[Production of Adhesive Composition and Adhesive Tape]

The solution of the (meth)acrylic polymer (A) obtained is diluted, and further, an epoxy crosslinking agent composed of glycerol diglycidyl ether is added to 100 parts of the (meth)acrylic polymer (A). 10 parts of the product (manufactured by Synthetic Chemical Co., Ltd., trade name E-5XM), the adhesive composition was obtained. The adhesive composition was applied to a polyimide substrate having a thickness of 25 μm so that the thickness after drying became the thickness shown in Table 1. Then, heat drying was carried out to remove the solvent, and an adhesive tape was obtained.

<evaluation test>

The adhesive tapes obtained in Examples 1 to 8 and Comparative Examples 1 and 2 were evaluated in accordance with the following methods. The results are shown in Table 1.

(initial adhesion)

The adhesion to the SUS plate was measured in accordance with JIS Z 0237 (2000).

(adhesion after heating at 300 ° C)

The adhesive tape was cut to a width of 10 mm to obtain a test piece. The test piece was attached to a SUS plate, allowed to stand in an oven at 300 ° C for 2 hours, and then left at room temperature (23 ° C) for 2 hours. Then, according to JIS Z 0237 (2000) (adhesive tape ‧ adhesive sheet test method), the adhesion was measured under the conditions of a peeling angle of 180 degrees and a peeling speed of 300 mm/min.

(Floating and peeling after heating at 300 °C)

In the above adhesion test after heating at 300 ° C, the adhesive tape was heated, and the adhesion was visually confirmed to be free from floating and peeling, and evaluated according to the following criteria.

"○": No floating or peeling occurred.

"X": There is a floating and / or peeling.

(Residual glue after heating at 300 °C ‧ pollution)

In the adhesion test after heating at 300 ° C described above, when the adhesive tape after heating was peeled off, the presence or absence of residual glue on the SUS plate was visually observed and contaminated, and evaluated according to the following criteria.

"○": No residual glue or contamination occurred.

"X": Residue and/or contamination has occurred.

The code numbers in Table 1 are as follows: "HEA": 2-hydroxyethyl acrylate

"4-HBA": 4-hydroxybutyl acrylate

"AE-200": polyethylene glycol monoacrylate (made by Nippon Oil Co., Ltd., BLEMMER (registered trademark) AE-200)

"AA": Acrylic

"2-EHA": 2-ethylhexyl acrylate

"MA": Methyl acrylate

<evaluation>

It can be seen from Table 1 that the adhesive strength of the adhesive tapes of Examples 1 to 8 after heating at 300 ° C is an appropriate value, and no floating, peeling, residual glue, or contamination occurs after heating at 300 ° C. Therefore, it is understood that these adhesive tapes are excellent in heat resistance and excellent in removability after heating.

The adhesive tapes of Examples 1 to 3 were all the same adhesive tape except for the thickness of the adhesive layer. Since the adhesive tape of Example 2 was thick, the initial adhesive force was significantly higher than that of the other examples (Examples 1 and 3). However, the adhesion after heating at 300 ° C is equivalent to that of the other examples. The adhesive tape of Example 3 had a slightly thinner adhesive layer, but the adhesive strength after heating at 300 ° C was the same as that of the other examples. From these results, it is understood that the thickness of the adhesive layer hardly affects the adhesion after heating at 300 °C.

The adhesive tapes of Examples 4 to 6 had an increased adhesive amount in addition to the amount of each monomer other than 2-EHA. Since the adhesive tapes of Examples 4 to 6 had a large amount of high Tg monomers, the initial adhesive strength was lower than that of Example 1. However, the adhesion after heating at 300 ° C is There is no problem at the level. It is understood from these results that the increase in the monomer having a higher Tg does not affect the post-adhesion of the 300 °C heating.

The adhesive tape of Comparative Example 1 is a hydroxyl group-containing (meth) acrylate monomer using only one long-chain monomer (4-HBA) adhesive tape, and the adhesive force after heating at 300 ° C is too low, and occurs after heating. Float situation. This phenomenon is presumed to be due to the fact that when only one long-chain monomer (4-HBA) is used, the entanglement of the molecular chain is insufficient and the thermal decomposition is liable to occur.

The adhesive tape of Comparative Example 2 is an adhesive tape in which the content of the carboxyl group-containing monomer (A3) is too small, and when it is peeled off after heating, residual glue may occur. This phenomenon is presumed to be a result of a decrease in the strength of the crosslinked structure due to a low crosslink density.

(industrial availability)

The adhesive composition of the present invention and the adhesive tape using the same are excellent in initial adhesion, and have heat resistance and re-peelability which can be used even at a high temperature of 300 ° C, and therefore can be effectively used for all applications requiring such characteristics. It is suitable for, for example, a substrate in which components are provided, a glass substrate, a sensor, a semiconductor, etc., and a manufacturing process in which a heat treatment step must be performed at a high temperature.

Claims (7)

An adhesive composition comprising: (meth)acrylic polymer (A) containing at least two or more hydroxyl group-containing (meth)acrylic acids represented by the following formulas (A1) and (A2) a monomer unit derived from the ester monomer, and a monomer unit derived from the carboxyl group-containing monomer (A3): 5.1 to 20% by mass; (In the formulae A1 and A2, R ¹ and R ² are a hydrocarbon group or a hydrocarbon group containing an oxygen atom; R ^{2 has} a larger number of carbon atoms than R ¹ ; R ³ is a hydrogen atom or a methyl group; x is a group 1~ 3); and an epoxy crosslinking agent (B). The adhesive composition of claim 1, wherein the epoxy-based crosslinking agent (B) is contained in an amount of 5 to 25 parts by mass based on 100 parts by mass of the (meth)acryl-based polymer (A). An adhesive tape provided with an adhesive layer formed of the adhesive composition of claim 1. The adhesive tape of claim 3, comprising: a substrate, and an adhesive layer on at least one of the substrates. The adhesive tape of claim 4, wherein the substrate is composed of a resin selected from the group consisting of polyphenylene sulfide, polyether oxime, polyether ether ketone, and polyimine. The adhesive tape of claim 3, wherein the thickness of the adhesive layer is 2 to 100 μm. The adhesive tape of claim 3, wherein the adhesive tape that has been attached to the SUS plate, After heating at 300 ° C for 2 hours and then standing at room temperature for 2 hours, the adhesive tape adhesion according to JIS Z 0237 (2000) was 0.03 to 1.5 N/10 mm.