JPWO2017145545A1 - Adhesive composition and adhesive tape - Google Patents

Abstract

（R¹,R²は炭化水素基又は酸素原子含有炭化水素基でR²の炭素原子数はR¹の炭素原子数より多く、R³は水素原子又はメチル基、xは1〜3である。)A monomer unit of two or more kinds 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 (meth) acrylic polymer (A) and an epoxy-based crosslinking agent (B) and a pressure-sensitive adhesive tape using the same are disclosed.
[Chemical 1]

(R ¹ and R ² are hydrocarbon groups or oxygen atom-containing hydrocarbon groups, R ² has more carbon atoms than R ¹ , R ³ is a hydrogen atom or methyl group, and x is 1 to 3. .)

Description

  The present invention relates to a pressure-sensitive adhesive composition that does not float or peel off even at high temperatures (for example, 300 ° C.), and that does not cause adhesive residue or contamination on the adherend even after peeling, and a pressure-sensitive adhesive tape using the same About.

  In general, pressure-sensitive adhesive tapes having an acrylic pressure-sensitive adhesive layer are frequently used in industrial applications such as the electric / electronic field because they are less susceptible to thermal deterioration in a high temperature environment. However, in recent years, in such industrial applications, the adhesive tape may be exposed to a higher temperature environment. Accordingly, there has been a demand for further improving the heat resistance of the acrylic pressure-sensitive adhesive. On the other hand, for example, in the heat treatment process, when a part is temporarily fixed with an adhesive tape, or when a surface that is easily damaged during processing / transportation is protected, the adhesive tape in use has a high adhesive force to the adherend. In addition, the adhesive tape after use is required to be easily peelable (removability). Therefore, various techniques have been proposed to improve these points.

  Patent Document 1 describes a heat-peelable thermosetting pressure-sensitive adhesive film in which an 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, since the three-dimensional cross-linking is quickly formed between the epoxy group and the carboxyl group by heating and cured, it is explained that the pressure-sensitive adhesive film can be easily peeled off from the adherend by reducing the adhesiveness. ing. Specifically, the heating temperature in the examples is 190 ° C., and it is described that it was able to be peeled easily due to the extremely low adhesive strength by heat curing.

  Patent Document 2 discloses an adhesive composed of an acrylic pressure-sensitive adhesive (C1) having a mass average molecular weight of 750,000 or more and an acid value of 5 or more and an acrylic pressure-sensitive adhesive (C2) having a mass average molecular weight of less than 400,000 and an acid value of 40 or more. An adhesive body which is a reaction product of an agent component and a crosslinking agent (D) is described. The high molecular weight component (C1) is a component that maintains the peeling force at high temperature by heating due to its cohesive force, and the low molecular weight component (C2) controls the peelability after heating to increase the removability. It is described as an ingredient. The heating temperature is 110 ° C to 170 ° C.

  Patent Document 3 states that the adhesive strength to stainless steel after 20 minutes when applied at 23 ° C. is 100 mN / inch or less, and the adhesive strength after heating at 170 ° C. for 1 hour after application is 200 mN / inch or less. An acrylic solvent-type pressure-sensitive adhesive composition containing an acrylic polymer (A) containing no group is described. It is described that it is important that the acrylic polymer (A) does not have a carboxyl group in order to obtain such ultra-adhesive strength.

  Patent Document 4 discloses an adhesive comprising an acrylic resin, a crosslinking agent for crosslinking the acrylic resin, a photocurable resin, and a photocuring agent for curing the photocurable resin. A composition is described. This pressure-sensitive adhesive composition has a low initial adhesive strength and can be easily re-applied, and does not float or peel off after being bonded to an adherend and is placed in a high-temperature environment. However, it is described that the adhesive force does not change, and the adhesive residue and adherend contamination can be reduced. The heating temperature in the examples is 230 ° C.

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

  Furthermore, although the purpose is different (for the purpose of providing a low-viscosity adhesive composition excellent in adhesive performance such as adhesive strength and low-temperature tack), Patent Document 6 has 3 or more carbon atoms. A pressure-sensitive adhesive comprising a hydroxyalkyl (meth) acrylate (a-2-1) having a hydroxyl group bonded to an alkyl group and a hydroxyl group-containing (meth) acrylate having a hydroxyl group bonded to a shorter alkyl group than (a-2-1) A composition is described.

  In recent years, with the development of technology, the temperature of the heating process has increased further, and for example, the number of processes for performing heat treatment for a short time at a high temperature of 300 ° C. has begun to increase. On the other hand, the pressure-sensitive adhesive compositions or pressure-sensitive adhesive tapes described in Patent Documents 1 to 5 have a heat resistance verification temperature of 230 ° C. at the most, and both heat resistance and removability are high even at higher temperatures (eg, 300 ° C.). The recent demand for excellence cannot be fully met. Furthermore, since the pressure-sensitive adhesive composition described in Patent Document 6 is not intended to improve heat resistance and uses only a small amount of an isocyanate curing agent, it is considered that the heat resistance is not sufficient.

JP 2003-238910 A JP 2003-292931 A JP 2004-217740 A International Publication No. 2015/119042 JP 2009-29948 A JP 2014-108968 A

  The object of the present invention is to have a sufficient initial adhesive force, and does not float or peel even at high temperatures (for example, 300 ° C.). Even if it is peeled off after heating, adhesive residue or contamination is generated on the adherend. It is providing the adhesive composition which does not, and an adhesive tape using the same.

  As a result of intensive studies aimed at achieving the above object, the present inventors have found that a composition comprising a (meth) acrylic polymer (A) having a specific copolymer composition and an epoxy crosslinking agent (B) is very effective. As a result, the present invention has been completed.

  That is, the present invention relates to 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. (Meth) acrylic polymer (A) containing at least a monomer unit derived from (A3)

(In Formulas A1 and A2, R ¹ and R ² are hydrocarbon groups or oxygen atom-containing hydrocarbon groups, R ² has more carbon atoms than R ¹ , and R ³ is a hydrogen atom or methyl. And x is 1 to 3), and an epoxy-based crosslinking agent (B)
Is a pressure-sensitive adhesive composition containing

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

  In the present invention, since it contains a (meth) acrylic polymer (A) having a specific copolymer composition and an epoxy-based crosslinking agent (B), it has a sufficient initial adhesive force and, for example, a general acrylic of 300 ° C. A pressure-sensitive adhesive composition that does not float or peel even at high temperatures far exceeding the decomposition temperature of the polymer, and does not cause adhesive residue or contamination on the adherend even if peeled after heating, and a pressure-sensitive adhesive tape using the same Can provide.

<Adhesive composition>
The pressure-sensitive adhesive composition of the present invention is a composition containing a (meth) acrylic polymer (A) and an epoxy-based crosslinking agent (B).

  The (meth) acrylic polymer (A) used in the pressure-sensitive adhesive composition is a monomer unit derived from two or more hydroxyl group-containing (meth) acrylate monomers represented by the following formulas (A1) and (A2): And at least a monomer unit derived from the 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 “hydroxyl group-containing short chain monomer (A1)”, and the hydroxyl group-containing (meth) acrylate monomer represented by the formula (A2) This is referred to as “hydroxyl-containing long-chain monomer (A2)”.

(In Formulas A1 and A2, R ¹ and R ² are hydrocarbon groups or oxygen atom-containing hydrocarbon groups, R ² has more carbon atoms than R ¹ , and R ³ is a hydrogen atom or methyl. And x is 1 to 3.)

In the prior art, when trying to improve the heat resistance characteristics of the pressure-sensitive adhesive composition, it is common to avoid the use of functional group-containing monomers as much as possible. However, in this invention, the heat resistance excellent in the adhesive composition is provided by using together a hydroxyl-containing short chain monomer (A1) and a hydroxyl-containing long chain monomer (A2). The reason is not necessarily clear. For example, the monomer unit derived from the hydroxyl group-containing short chain monomer (A1) is difficult to thermally decompose, and the monomer unit derived from the hydroxyl group-containing long chain monomer (A2) is initially Contributes to the improvement of adhesive strength and also contributes to the improvement of heat resistance by entanglement of the long chain R ² , and the cross-linking reaction occurs in a stepwise manner, and both the above-mentioned actions synergistically provide an appropriate adhesive strength even after high temperature heating This is presumed to be due to the fact that

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 any hydrocarbon group or oxygen atom-containing hydrocarbon group, and the kind thereof is not particularly limited. Either saturated or unsaturated may be used, but a saturated hydrocarbon group and an oxygen atom-containing saturated hydrocarbon group are preferred. Moreover, although aliphatic and aromatic may be sufficient, an aliphatic hydrocarbon group and an oxygen atom containing aliphatic saturated hydrocarbon group are preferable. Further, in the case of an aliphatic group, it may be any of linear, branched, and alicyclic. A linear or branched aliphatic hydrocarbon group and an oxygen atom-containing linear or branched aliphatic hydrocarbon group are preferred, and a linear aliphatic hydrocarbon group and an oxygen atom-containing linear aliphatic hydrocarbon group Is 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, Specific examples of the hydrocarbon group having a hydroxyl group include a hydroxyethyl group, a 2-hydroxypropyl group, a 3-hydroxypropyl group, a 2-hydroxy-1-methylethyl group, a 2-hydroxybutyl group, and a 3-hydroxybutyl group. 4-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- Examples thereof include unsaturated aliphatic hydrocarbon groups having a hydroxyl group such as a hydroxyoctyl group and 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 oxygen atom-containing hydrocarbon groups, -R ^1- (OH) x and -R ^2- (OH) Specific examples of x (that is, an oxygen atom-containing hydrocarbon group having a hydroxyl group) include a group represented by — (OR) n—OH (for example, a polyalkylene glycol such as a polyethylene glycol group, a polypropylene glycol group, and a polybutylene glycol group). Group), 2- (2-hydroxyethoxy) ethyl group, 2-hydroxy-3-methoxypropyl group, 2-hydroxy-3-butoxypropyl group and the like, and oxygen atom unsaturated aliphatic hydrocarbon groups having a hydroxyl group. .

The number of carbon atoms of R ² of the hydroxyl group-containing long chain monomer (A2) is larger than the number of carbon atoms of R ¹ of the hydroxyl group-containing short chain monomer (A1). Specifically, the difference between the number of carbon atoms of R ^{2 and} the number of carbon atoms of R ¹ is 1 or more, preferably 2 or more, more preferably 2 or more and 8 or less. In particular, when this difference is 2 or more, a more remarkable effect can be obtained in terms of heat resistance (for example, improvement of adhesive strength after heating, prevention of occurrence of lifting). This is presumed to be because the molecular chain becomes more entangled. Therefore, it is preferable that the number of carbon atoms in R2 of the hydroxyl group-containing long chain monomer (A2) is appropriately large. However, when the amount is too large, the ratio of the amount of hydroxyl group to the amount of R ² is relatively undesirably lowered. Specifically, the number of carbon atoms in R ² of the hydroxyl group-containing long chain monomer (A2) is 2 or more, preferably 3 or more, more preferably 4 or more and 12 or less. The number of carbon atoms of R ^{1 in} the hydroxyl group-containing short chain monomer (A1) is 1 or more, preferably 1 or more and 4 or less, more preferably 2 or more and 3 or less.

Each R ³ in 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 and R ³ of the hydroxyl group-containing long-chain monomer (A2) of the hydroxyl group-containing short chain monomer (A1) may be mutually the same or may be different.

X of the hydroxyl group-containing short chain monomer (A1) and the hydroxyl group-containing long chain monomer (A2) represents the number of hydroxyl groups— (OH) bonded to R ¹ and R ² . x is 1 to 3, preferably 1 to 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 or different.

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, with respect to the bonding position of — (OH) to R ² of the hydroxyl group-containing long-chain monomer (A2), the molecular end side of R ² (end far from the (meth) acryloyl group) is preferable.

  As particularly preferred specific examples of the hydroxyl group-containing short chain monomer (A1) and the hydroxyl group-containing long chain monomer (A2), 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meta) ) Acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate and other (meth) acrylic acid hydroxyalkyl esters; polyethylene glycol monoacrylate, polypropylene glycol monoacrylate, etc. Polyalkylene glycol monoacrylate. That is, it is preferable to select and use two or more types of monomers from these.

  In 100% by mass of the monomer unit constituting the (meth) acrylic polymer (A), the monomer unit derived from the hydroxyl group-containing short chain monomer (A1) and the single unit derived from the hydroxyl group-containing long chain monomer (A2) The total content of body units is preferably 5 to 20% by mass, more preferably 10 to 15% by mass. Further, the content of the monomer unit resulting from the hydroxyl group-containing long chain monomer (A2) is preferably larger than the content of the monomer unit resulting from the hydroxyl group-containing short chain monomer (A1). Thereby, a more remarkable effect is obtained in terms of heat resistance (for example, improvement of adhesive strength after heating, prevention of occurrence of floating). Specifically, the blending 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 improves the physical properties such as cohesive force through a crosslinking reaction with the epoxy-based crosslinking agent (B), and can thereby suppress adhesive residue at the time of re-peeling. The carboxyl group-containing monomer (A3) is not particularly limited as long as it is a compound having 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- Carboxy-polycaprolactone (repeating unit (n) = about 2) monoacrylate (for example, Toagosei Co., Ltd., trade name M-5300), phthalic acid monohydroxyethyl acrylate (for example, Toagosei Co., Ltd., trade name M-5400), An acrylic acid dimer (for example, trade name M-5600, manufactured by Toagosei Co., Ltd.) can be mentioned. Two or more kinds of carboxyl group-containing monomers (A3) may be used in combination. Among these, (meth) acrylic monomers (that is, monomers having a (meth) acryloyl group) are preferable, and acrylic acid and methacrylic acid are particularly preferable.

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

  The (meth) acrylic polymer (A) may contain monomer units derived from other monomers other than the monomers described above. As the other monomer, a (meth) acrylate monomer containing no hydroxyl group or carboxyl group is preferable, an alkyl (meth) acrylate monomer is more preferable, and an alkyl (meth) acrylate monomer having an alkyl group having 1 to 12 carbon atoms is particularly preferable. preferable. Specific examples include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 2-methylbutyl (meta ), Acrylate, isoamyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, dodecyl (meth) acrylate, and the like, having an alkyl group having 1 to 12 carbon atoms. Examples include alkyl (meth) acrylate; phenoxyethyl (meth) acrylate; tetrahydrofurfuryl (meth) acrylate; alkoxyalkyl (meth) acrylate. Furthermore, desired monomers other than the (meth) acrylate monomer can be used in combination.

  Monomer derived from (meth) acrylate monomer (more preferably alkyl (meth) acrylate monomer) containing no hydroxyl group or carboxyl group in 100% by mass of monomer units constituting (meth) acrylic polymer (A). The content of the unit is preferably 60 to 90% by mass, more preferably 70 to 85% by mass.

  The (meth) acrylic polymer (A) can be obtained by copolymerizing the components described above. The polymerization method is not particularly limited, and various known methods can be used, but radical solution polymerization is particularly preferable. The radical solution polymerization is generally performed in 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 pressure-sensitive adhesive composition is a component that improves the cohesive strength of the pressure-sensitive adhesive composition by crosslinking reaction with the carboxyl group and / or hydroxyl group of the (meth) acrylic polymer (A). . Moreover, in the present invention, the epoxy-based crosslinking agent (B) greatly contributes to the improvement of heat resistance. The reason is not necessarily clear. For example, even if the (meth) acrylic polymer (A) contains many functional groups such as a carboxyl group and a hydroxyl group, the site in the molecule that is easily thermally decomposed is an epoxy crosslinking agent. It is speculated that this is due to being capped with (B) and difficult to thermally decompose. According to the knowledge of the present inventors, when a crosslinking agent (specifically, an isocyanate crosslinking agent) other than the epoxy crosslinking agent (B) is used, the pressure-sensitive adhesive composition tends to gel before coating. Application to the substrate becomes difficult.

  Specific examples of the epoxy-based crosslinking agent (B) include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl. Examples include ether, diglycidyl aniline, N, N, N ′, N′-tetraglycidyl-m-xylylenediamine, 1,3-bis (N, N′-diglycidylaminomethyl) cyclohexane. Two or more types of epoxy crosslinking agents (B) may be used in combination.

  The content of the epoxy crosslinking agent (B) is preferably 5 to 25 parts by mass, more preferably 7 to 18 parts by mass, particularly preferably 8 to 15 parts per 100 parts by mass of the (meth) acrylic polymer (A). Part by mass.

  Furthermore, the pressure-sensitive adhesive composition may contain any resin component other than the (meth) acrylic polymer (A) within a range not impairing the effects of the present invention. Moreover, the other additive component may be included as needed. Specific examples of the additive component include a solvent, an antioxidant, an ultraviolet absorber, a light stabilizer, an antistatic agent, a filler, and a pigment.

<Adhesive tape>
The pressure-sensitive adhesive tape of the present invention has a pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition of the present invention described above. Typically, an adhesive tape has a base material and an adhesive layer on at least one surface of the base material. However, the pressure-sensitive adhesive tape of the present invention is not limited thereto, and may be, for example, a baseless type pressure-sensitive adhesive tape having no base material.

  The thickness of the pressure-sensitive adhesive layer in the pressure-sensitive adhesive tape having a substrate is preferably 2 to 100 μm, more preferably 3 to 80 μm, and particularly preferably 4 to 70 μm. The same applies to the thickness of the adhesive layer in the baseless type adhesive tape.

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

  The kind of base material used for the adhesive tape is not particularly limited, and may be appropriately selected according to the performance (heat resistance, etc.) required at the time of use. For example, when the use temperature of the adhesive tape is less than 150 ° C., a known resin substrate such as polyethylene terephthalate (PET) may be used. When the use temperature of the adhesive tape is 150 ° C. or higher, a resin base material excellent in heat resistance is preferable, specifically, a resin selected from the group consisting of polyphenylene sulfide, polyether imide, polyether ether ketone and polyimide. A constructed substrate is preferred. Especially, the base material comprised with a polyimide is especially preferable. The thickness of the substrate is preferably 12.5 to 125 μm, more preferably 17.5 to 50 μm. The pressure-sensitive adhesive layer may be formed only on one side of the substrate, or may be formed on both sides to form a double-sided pressure-sensitive adhesive tape.

  The pressure-sensitive adhesive tape of the present invention preferably has an appropriate pressure-sensitive adhesive force upon re-peeling after heating. This can be specified by, for example, the adhesive strength of the adhesive tape after heating at 300 ° C. for 2 hours. Specifically, the pressure-sensitive adhesive strength of the pressure-sensitive adhesive tape according to JIS Z 0237 (2000) after heating the pressure-sensitive adhesive tape bonded to the SUS plate at 300 ° C. for 2 hours and then leaving it at room temperature (23 ° C.) for 2 hours is Preferably it is 0.03-1.5N / 10mm, More preferably, it is 0.05-1.0N / 10mm, Most preferably, it is 0.1-0.4N / 10mm. Details of the measurement conditions are described in the column of Examples.

  Hereinafter, the present invention will be described in more detail with reference to 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 added to the solvent at a blending ratio (% by mass) shown in Table 1, and a polymerization initiator (trade name V-, manufactured by Wako Pure Chemical Industries, Ltd.) composed of 2,2′-azobis (2-methylbutyronitrile) was used. 59) is added in an amount of 0.2 part to 100 parts of the monomer, heated at 70 ° C. under a nitrogen atmosphere, and then heated at 90 ° C. to obtain a (meth) acrylic polymer (A) solution having a solid content of 30%. Got.

[Preparation of pressure-sensitive adhesive composition and pressure-sensitive adhesive tape]
The obtained (meth) acrylic polymer (A) solution was diluted, and an epoxy cross-linking agent (trade name E-5XM, manufactured by Soken Chemical Co., Ltd.) consisting of glycerin diglycidyl ether was further added to the (meth) acrylic polymer (A ) 10 parts were added to 100 parts to obtain an adhesive composition. This pressure-sensitive adhesive composition was applied on a polyimide substrate having a thickness of 25 μm so that the thickness after drying was as shown in Table 1. Thereafter, the solvent was removed by drying by heating to obtain an adhesive tape.

<Evaluation test>
The adhesive tapes obtained in Examples 1-8 and Comparative Examples 1-2 were evaluated by the following methods. The results are shown in Table 1.

(Initial adhesive strength)
In accordance with JIS Z 0237 (2000), the adhesive strength to the SUS plate was measured.

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

(Floating / peeling after heating at 300 ° C)
In the above-mentioned adhesive strength test after heating at 300 ° C., the adhesive tape was heated, and then the presence or absence of lifting / peeling of the adhesive tape was visually confirmed and evaluated according to the following criteria.
“◯”: Lifting and peeling did not occur.
“X”: floating and / or peeling occurred.

(Adhesive residue and contamination after heating at 300 ° C)
In the adhesive strength test after heating at 300 ° C. described above, when the heated adhesive tape was peeled off, the presence or absence of adhesive residue / contamination on the SUS plate was visually confirmed and evaluated according to the following criteria.
“◯”: No adhesive residue or contamination occurred.
“X”: adhesive residue and / or contamination occurred.

Abbreviations in Table 1 are as follows.
“HEA”: 2-hydroxyethyl acrylate “4-HBA”: 4-hydroxybutyl acrylate “AE-200”: polyethylene glycol monoacrylate (manufactured by NOF Corporation, Blemmer (registered trademark) AE-200)
“AA”: acrylic acid “2-EHA”: 2-ethylhexyl acrylate “MA”: methyl acrylate

<Evaluation>
As is apparent from Table 1, the adhesive tapes of Examples 1 to 8 had an appropriate value of adhesive strength after heating at 300 ° C., and neither floating nor peeling after heating at 300 ° C., and no adhesive residue or contamination occurred. Therefore, it can be understood that these pressure-sensitive adhesive tapes are excellent in heat resistance and re-peelability after heating.

  The adhesive tapes of Examples 1 to 3 are the same adhesive tape except that the thickness of the adhesive layer is different. Since the pressure-sensitive adhesive tape of Example 2 had a thick pressure-sensitive adhesive layer, the initial adhesive force was considerably higher than those of the other examples (Examples 1 and 3). However, the adhesive strength after heating at 300 ° C. was the same level as in the other examples. The pressure-sensitive adhesive tape of Example 3 had a slightly thin pressure-sensitive adhesive layer, but the adhesive strength after heating at 300 ° C. was at the same level as other examples. 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 to 6 are adhesive tapes in which the amount of each monomer other than 2-EHA is increased. The adhesive tapes of Examples 4 to 6 had a lower initial adhesive force than that of Example 1 because the amount of the monomer having a relatively high Tg was large. However, the adhesive strength after heating at 300 ° C. was at a level with no problem. From these results, it can be understood that the increase in the monomer having a relatively high Tg does not significantly affect the adhesive strength after heating at 300 ° C.

  The pressure-sensitive adhesive tape of Comparative Example 1 is a pressure-sensitive adhesive tape using only one type of long-chain monomer (4-HBA) as a hydroxyl group-containing (meth) acrylate monomer. The pressure-sensitive adhesive strength is too low after heating at 300 ° C. Occurred. This is presumably due to the fact that when only one type of long-chain monomer (4-HBA) is used, the entanglement of the molecular chains is insufficient and thermal decomposition is easy.

  The pressure-sensitive adhesive tape of Comparative Example 2 was a pressure-sensitive adhesive tape with too little content of the carboxyl group-containing monomer (A3), and adhesive residue was generated at the time of peeling after heating. This is presumed to be due to the fact that the strength of the crosslinked structure was lowered because the crosslinking density was low.

  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 have heat resistance and removability that can be used even at a high temperature of 300 ° C., so these characteristics are required. Useful for any application. For example, it can be suitably used in a manufacturing process that requires a heat treatment process at a high temperature, such as a component-embedded substrate, a glass substrate, a sensor, or a semiconductor.

Claims (7)

Due to two or more kinds 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

(In Formulas A1 and A2, R ¹ and R ² are hydrocarbon groups or oxygen atom-containing hydrocarbon groups, R ² has more carbon atoms than R ¹ , and R ³ is a hydrogen atom or methyl. And x is 1 to 3), and an epoxy-based crosslinking agent (B)
A pressure-sensitive adhesive composition containing   The pressure-sensitive adhesive composition according to claim 1, comprising 5 to 25 parts by mass of the epoxy-based crosslinking agent (B) with respect to 100 parts by mass of the (meth) acrylic polymer (A).   A pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition according to claim 1.   The pressure-sensitive adhesive tape according to claim 3, comprising a base material and a pressure-sensitive adhesive layer on at least one surface of the base material.   The pressure-sensitive adhesive tape according to claim 4, wherein the substrate is composed of a resin selected from the group consisting of polyphenylene sulfide, polyetherimide, polyetheretherketone and polyimide.   The pressure-sensitive adhesive tape according to claim 3, wherein the pressure-sensitive adhesive layer has a thickness of 2 to 100 µm.   The pressure-sensitive adhesive strength of the pressure-sensitive adhesive tape according to JIS Z 0237 (2000) after heating the pressure-sensitive adhesive tape bonded to the SUS plate at 300 ° C. for 2 hours and then standing at room temperature for 2 hours is 0.03 to 1.5 N / 10 mm. The pressure-sensitive adhesive tape according to claim 3.