JP2023023563A - Adhesive composition and adhesive processed product - Google Patents

Abstract

To provide an adhesive composition capable of forming an adhesive layer that is highly transparent and has sufficient adhesiveness even as a thin film.SOLUTION: The adhesive composition contains: a (meth)acrylic resin (A) in an amount from 47 pts.mass to 99 pts.mass inclusive; a (co)polymer (B) different from the (meth)acrylic resin (A) in an amount from 0.5 pt.mass to 50 pts.mass inclusive; and a cross-linking agent (C) in an amount from 0.5 pt.mass to 3 pts.mass; where the total content of the (meth)acrylic resin (A), the (co)polymer (B) and the cross-linking agent (C) is 100 pts.mass. The (meth)acrylic resin (A) satisfies specific requirements (A-1) and (A-2), and the (co)polymer (B) satisfies all of specific requirements (B-1) to (B-5).SELECTED DRAWING: None

Description

The present invention relates to adhesive compositions and adhesive processed goods.

Adhesives (also referred to as pressure-sensitive adhesives) are easy to use and have adhesiveness to various objects such as plastics, papers, metals and glass. Therefore, it is widely used as an adhesive layer for adhesive products such as tapes, labels, sheets and double-sided tapes. As the composition (adhesive composition) used for the adhesive, a composition having an acrylic resin or a styrene resin (such as a styrene-based block copolymer) as a base polymer is generally used.

In particular, adhesive compositions containing acrylic resins as base polymers are known to be excellent in transparency and adhesiveness to polar adherends such as papers, metals and glass.

On the other hand, along with the thinning of electronic devices and the like, there is a growing demand for thinner double-sided tapes that bond internal members together. Therefore, the adhesive composition is desired to have sufficient adhesiveness and adhesion even when formed into a thin adhesive layer.

In response to the above requirements, a method of adding a tackifying resin such as a rosin-based resin, a terpene-based resin, and a petroleum-based resin to an acrylic adhesive composition to further increase the adhesiveness of the adhesive composition has been proposed. . For example, in Patent Document 1, by adding a tackifying resin having low compatibility with (meth)acrylic polymers, such as rosin resin, to an acrylic adhesive composition, both normal temperature and high temperature adhesion are exhibited. It is stated that it is possible to Patent Document 1 describes that the tackifying resin is added so that the adhesive composition has a haze value of 15 to 95% when formed into a film.

JP-A-64-16882

Patent Document 1 describes that the addition of a tackifying resin such as the rosin-based resin described above can further increase the adhesiveness of the adhesive composition. However, as described in Patent Document 1, the addition of the tackifying resin reduces the transparency of the adhesive composition.

The present invention has been made in view of the above circumstances, an adhesive composition capable of obtaining an adhesive layer having sufficient adhesiveness even in a thin film and having high transparency, and obtained from the adhesive composition The object is to provide a self-adhesive article having a self-adhesive layer.

That is, the present invention provides the following adhesive composition.
47 parts by mass or more and 99 parts by mass or less (meth)acrylic resin (A) and 0.5 parts by mass or more and 50 parts by mass or less of a (co)polymer different from the (meth)acrylic resin (A) ) and 0.5 parts by mass or more and 3 parts by mass or less of a cross-linking agent (C) (wherein (meth)acrylic resin (A), (co)polymer (B), and cross-linking agent (C ) is 100 parts by mass), the (meth)acrylic resin (A) satisfies the following requirements (A-1) and (A-2), and the (co)polymer ( B) is an adhesive composition that satisfies all of the following requirements (B-1) to (B-5).
(A-1) contains a structural unit derived from a (meth)acrylate having an alkyl group having 1 to 12 carbon atoms and a structural unit derived from a (meth)acrylate containing a hydroxyl group.
(A-2) The glass transition temperature (Tg) measured by a differential scanning calorimeter (DSC) is in the range of -80°C or higher and 0°C or lower.
(B-1) Structural units derived from isopropenyltoluene are contained in an amount of 20 mol% or more based on the total amount of structural units of the (co)polymer (B).
(B-2) The softening point measured according to JIS K2207 is in the range of 80°C or higher and 120°C or lower.
(B-3) The glass transition temperature (Tg) measured by a differential scanning calorimeter (DSC) is in the range of 30°C or higher and 70°C or lower.
(B-4) The polystyrene-equivalent number-average molecular weight (Mn) measured by gel permeation chromatography (GPC) is in the range of 750 or more and 1200 or less, and the z-average molecular weight (Mz) is in the range of 2000 or more and 3000 or less. and the dispersity (Mw/Mn), which is the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn), is 1.5 or more and 1.8 or less.
(B-5) The solubility parameter is 9.80 (cal/cm ³ ) ^1/2 or less.

The present invention also provides the following adhesive processed goods.
An adhesive processed article having an adhesive layer obtained from the above adhesive composition and being a tape, label, sheet or double-sided tape.

According to the adhesive composition of the present invention, it is possible to obtain a highly transparent adhesive layer having sufficient adhesiveness even in a thin film. In addition, adhesive processed products having an adhesive layer obtained from the adhesive composition can be used for various purposes.

1 is a graph showing the relationship between the total light transmittance of adhesive processed products of Examples 1 and 2 and Comparative Examples 1 to 7 and the adhesive strength of the adhesive layer of the adhesive processed products.

One embodiment of the present invention relates to an adhesive composition containing a (meth)acrylic resin (A) satisfying specific requirements, a (co)polymer (B) satisfying specific requirements, and a cross-linking agent (C). . In this specification, (meth) acrylic means "acrylic, methacrylic, or both", (meth) acrylate means "acrylate, methacrylate, or both", and (co)polymer means "homopolymer, copolymer, or both."

[(Meth) acrylic resin (A)]
The (meth)acrylic resin (A) is a (co)polymer of acrylic monomers or methacrylic monomers.

The (meth)acrylic resin (A) satisfies the following requirements (A-1) and (A-2).
(A-1) It contains a structural unit derived from a (meth)acrylate having an alkyl group having 1 to 12 carbon atoms and a structural unit derived from a (meth)acrylate containing a hydroxyl group.
(A-2) The glass transition temperature (Tg) measured by a differential scanning calorimeter (DSC) is in the range of -80°C or higher and 0°C or lower.

(Regarding requirement (A-1))
Requirement (A-1) is a requirement for increasing the adhesiveness of the adhesive composition according to the present embodiment.

Specifically, when the (meth)acrylic resin (A) contains a structural unit derived from a (meth)acrylate having an alkyl group having 1 to 12 carbon atoms, the glass of the (meth)acrylic resin (A) The transition temperature (Tg) becomes 0° C. or lower, and the adhesiveness of the adhesive composition is further increased.

From the above viewpoint, the (meth)acrylate having an alkyl group having 1 to 12 carbon atoms is preferably a (meth)acrylate having an alkyl group having 1 to 10 carbon atoms, and has 2 to 8 carbon atoms. A (meth)acrylate having an alkyl group of is more preferable. The alkyl group may be linear or branched.

Examples of (meth)acrylates having an alkyl group having 1 to 12 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, and (meth)acrylic acid. Isopropyl, n-butyl (meth)acrylate, isobutyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, (meth)acrylic Examples include isooctyl acid, 2-ethylhexyl (meth)acrylate, decyl (meth)acrylate, and lauryl (meth)acrylate.

The amount of structural units derived from (meth)acrylate having an alkyl group having 1 to 12 carbon atoms with respect to the total amount of structural units of the (meth)acrylic resin (A) is 50 mol% or more and 99 mol% or less. It is preferably 55 mol % or more and 95 mol % or less, and even more preferably 60 mol % or more and 90 mol % or less.

Further, when the (meth)acrylic resin (A) contains a structural unit derived from a (meth)acrylate containing a hydroxyl group, the number of crosslink points by the crosslinker (C) increases, so that the crosslink density of the adhesive composition increases. It becomes easier to increase the molecular weight. According to such an adhesive composition, the entanglement between the polymers is strengthened, and the adhesiveness at the time of pressure bonding is less likely to decrease.

A (meth)acrylate containing a hydroxyl group may have only one hydroxyl group in its molecule, or may have two or more hydroxyl groups. Examples of (meth)acrylates containing hydroxyl groups include hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate and N-methylol (meth)acrylamide. Among these, from the above viewpoint, the (meth)acrylate containing the hydroxyl group is preferably hydroxyethyl (meth)acrylate.

The content of the structural unit derived from the (meth)acrylate containing a hydroxyl group is preferably 0.1 mol% or more and 5 mol% or less, and 0.2, based on the total amount of the structural units of the (meth)acrylic resin (A). mol % or more and 3 mol % or less is more preferable, and 0.3 mol % or more and 2 mol % or less is even more preferable.

The (meth)acrylic resin (A) is a (meth)acrylate having an alkyl group having 1 or more and 12 or less carbon atoms or a (meth)acrylic resin (A) containing a hydroxyl group within a range that does not impair the purpose and effect of the present embodiment. It may further have a structural unit derived from a monomer (or oligomer) polymerizable with acrylate. Examples of the monomer include monomers (or oligomers thereof) capable of forming a crosslinked structure by reacting with the crosslinking agent (C), and vinyl-based monomers (or oligomers thereof). Examples of monomers capable of forming a crosslinked structure include (meth)acrylic acid, (meth)acrylamide, and the like. On the other hand, examples of vinyl-based monomers include styrene and vinyl acetate.

(Regarding requirement (A-2))
Requirement (A-2) is a requirement for suitably exhibiting the adhesiveness of the adhesive composition of the present embodiment over a wider temperature range.

Specifically, the (meth)acrylic resin (A) is a copolymer having a glass transition temperature (Tg) measured by a differential scanning calorimeter (DSC) in the range of −80° C. or higher and 0° C. or lower. , the adhesive composition formed into a thin adhesive layer can develop adhesiveness in a wide temperature range. From the above viewpoint, the (meth)acrylic resin (A) preferably has a glass transition temperature (Tg) in the range of -70°C or higher and -5°C or lower, and in the range of -60°C or higher and -10°C or lower. is more preferable.

The glass transition temperature (Tg) of the (meth)acrylic resin (A) is the (meth)acrylate having an alkyl group having 1 or more and 12 or less carbon atoms, which is used when polymerizing the (meth)acrylic resin (A). , the type and ratio of (meth)acrylate containing a hydroxyl group.

In the present embodiment, the glass transition temperature (Tg) of the (meth)acrylic resin (A) can be calculated from a theoretical calculation value determined by the following FOX formula.
1/Tg=W1/Tg1+W2/Tg2+...+Wn/Tgn
(Wherein, Tg is the glass transition temperature (K) of the acrylic resin (A), W1, W2, ..., Wn are the weight fractions of each monomer, Tg1, Tg2, ... , Tgn is the glass transition temperature of the homopolymer of each monomer)
As the glass transition temperature of the homopolymer used for the above calculation, the value described in the literature can be used.

(Synthesis method)
The (meth)acrylic resin (A) that satisfies the above requirements (A-1) and (A-2) is synthesized by a known polymerization method using monomers (or oligomers) that serve as materials for the above structural units. can get. The polymerization method is not particularly limited as long as it is a radical polymerization method including a bulk polymerization method, a solution polymerization method, a suspension polymerization method, and the like. Among these, the solution polymerization method is preferable from the viewpoint that the glass transition temperature (Tg) of the (meth)acrylic resin (A) and other properties can be easily controlled.

A polymerization initiator may be used during the polymerization. Examples of the polymerization initiators include dicumyl peroxide, benzoyl peroxide, t-butylperoxy-2-ethylhexanoate, 1,1-bis(t-butylperoxy)cyclohexane, α,α'- azobisisobutyronitrile, acetyl peroxide, t-butyl peroxypivalate, t-butyl hydroperoxide, cumene hydroperoxide, t-hexyl peroxypivalate, 2,2'-azobis-(2,4 -dimethylvaleronitrile), lauryloyl peroxide, t-butyl peroxyneohexanoate, di-t-butyl peroxide, azodicyclohexylcarbonitrile, dimethyl α,α-azodiisobutyrate, succinic acid peroxide, dicumene Peroxides, dichlorobenzoyl peroxide, and the like.

Examples of solvents used in the solution polymerization include ethyl acetate, butyl acetate, benzene, toluene, xylene, cyclohexane, methyl ethyl ketone and the like.

[(Co)polymer (B)]
The (co)polymer (B) is a (co)polymer different from the (meth)acrylic resin (A) and satisfies all of the following requirements (B-1) to (B-5) (co) It is a polymer.

(B-1) Structural units derived from isopropenyltoluene are contained in an amount of 20 mol% or more relative to the total amount of structural units of the (co)polymer (B).
(B-2) The softening point measured according to JIS K2207 is in the range of 80°C or higher and 120°C or lower.
(B-3) The glass transition temperature (Tg) measured by a differential scanning calorimeter (DSC) is in the range of 30°C or higher and 70°C or lower.
(B-4) The polystyrene-equivalent number-average molecular weight (Mn) measured by gel permeation chromatography (GPC) is in the range of 750 or more and 1200 or less, and the z-average molecular weight (Mz) is in the range of 2000 or more and 3000 or less. and the dispersity (Mw/Mn), which is the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn), is 1.5 or more and 1.8 or less.
(B-5) The solubility parameter is 9.80 (cal/cm ³ ) ^1/2 or less.

(Regarding requirement (B-1))
Requirement (B-1) is a requirement for increasing the adhesiveness without reducing the transparency of the adhesive composition of the present embodiment.

Specifically, the (co)polymer (B) contains 20 mol% or more of isopropenyltoluene (o-isopropenyltoluene, m-isopropenyltoluene, p-isopropenyltoluene) relative to the total amount of its structural units. containing isotopes), the solubility parameter (SP value) of the (co)polymer (B) is the SP value (8.6 to 9.1) of the (meth)acrylic resin (A) and get closer. Therefore, the (meth)acrylic resin (A) and the (co)polymer (B) are easily compatible, and the (co)polymer (B) is easily finely dispersed in the (meth)acrylic resin (A). It is considered to be.

The content of structural units derived from isopropenyltoluene is preferably 30 mol% or more, more preferably 45 mol% or more, and even more preferably 60 mol% or more, relative to the total amount of structural units of the (co)polymer (B). . The upper limit of the content of structural units derived from isopropenyltoluene is not particularly limited, but as described later, the (co)polymer (B) is composed of an unsaturated aliphatic hydrocarbon compound having 4 or 5 carbon atoms. It is preferable that 10 mol % or more of the structure derived from the monomer is included. Therefore, the amount of structural units derived from isopropenyltoluene is preferably 90 mol % or less, more preferably 89 mol % or less, and even more preferably 88 mol % or less.

(Regarding requirement (B-2))
Requirement (B-2) is a requirement for setting the viscosity of the adhesive composition of the present embodiment within a desired range.

Specifically, when the softening point of the (co)polymer (B) measured by a differential scanning calorimeter (DSC) is in the range of 80° C. or higher and 120° C. or lower, the viscosity of the adhesive composition is adjusted to an appropriate range. easy to adjust. That is, it becomes easier to apply the adhesive composition to the substrate. From the above viewpoint, the softening point of the (co)polymer (B) is preferably 85° C. or higher and 115° C. or lower, more preferably 90° C. or higher and 110° C. or lower, and even more preferably 95° C. or higher and 105° C. or lower.

The softening point of the (co)polymer (B) can be adjusted by the type of monomers to be copolymerized, the molecular weight, the molecular weight distribution, and the like.

(Regarding requirement (B-3))
Requirement (B-3) is a requirement for adjusting both transparency and adhesiveness to suitable ranges while increasing the heat resistance of the adhesive composition of the present embodiment.

Specifically, when the glass transition temperature (Tg) of the (co)polymer (B) measured according to JIS K2207 is 30°C or higher, the heat resistance of the adhesive composition is further enhanced. Moreover, when the (co)polymer (B) has a glass transition temperature (Tg) of 70° C. or lower, both the transparency and the adhesiveness of the adhesive composition tend to fall within suitable ranges. From the above viewpoint, the glass transition temperature (Tg) of the (co)polymer (B) is preferably 35°C or higher and 65°C or lower, more preferably 40°C or higher and 60°C or lower, and even more preferably 45°C or higher and 55°C or lower.

The glass transition temperature (Tg) of the (co)polymer (B) can be adjusted by the type of monomer to be copolymerized, the molecular weight, the molecular weight distribution, and the like.

In the present invention, the glass transition temperature (Tg) of the (co)polymer (B) can be calculated from a theoretically calculated value determined by the FOX formula described above.

(Regarding requirement (B-4))
Requirement (B-4) is a requirement for increasing the adhesiveness without reducing the transparency of the adhesive composition according to the present embodiment.

Specifically, the (co)polymer (B) has a polystyrene-equivalent number-average molecular weight (Mn) of 750 or more and 1200 or less, measured by gel permeation chromatography (GPC), and a z-average molecular weight of (Mz) is in the range of 2000 or more and 3000 or less, and the dispersity (Mw/Mn), which is the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn), is 1.5 or more and 1.8 or less be. When the number average molecular weight (Mn) is within this range, the adhesiveness is less likely to decrease. Further, transparency is maintained when the z-average molecular weight (Mz) is within the range. Furthermore, when the degree of dispersion (Mw/Mn) is within the range, the adhesiveness is improved.

The number average molecular weight (Mn) of the (co)polymer (B) is preferably 780 or more and 1180 or less, more preferably 800 or more and 1150 or less, and even more preferably 850 or more and 1100 or less.

The z-average molecular weight (Mz) of the (co)polymer (B) is preferably 2050 or more and 2800 or less, more preferably 2100 or more and 2500 or less.

Furthermore, the dispersity (Mw/Mn), which is the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the (co)polymer (B), is preferably 1.51 or more and 1.7 or less, 1.52 or more and 1.6 or less are more preferable.

The number average molecular weight (Mn), the z average molecular weight (Mz), and the dispersity (Mw/Mn), which is the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn), of the (co)polymer (B) can be adjusted to the above range by the type of monomers to be copolymerized, distillation under reduced pressure, or the like.

(Regarding Requirement (B-5) Requirement (B-5) is a requirement for improving the transparency of the adhesive composition of the present embodiment.

Specifically, when the (co)polymer (B) has a solubility parameter of 9.80 (cal/cm ³ ) ^1/2 or less, it becomes close to the solubility parameter of the (meth)acrylic resin (A). As a result, the compatibility between the (meth)acrylic resin (A) and the (co)polymer (B) becomes very good, and the (co)polymer (B) in the (meth)acrylic resin (A) , becomes difficult to see. That is, the transparency of the adhesive composition is improved. The solubility parameter of the (co)polymer (B) is preferably 9.50 (cal/cm ³ ) ^1/2 or more and 9.79 (cal/cm ³ ) ^1/2 or less, and 9.56 (cal/cm ^{3 )} . ) ^1/2 or more and 9.78 (cal/cm ³ ) ^1/2 or less is more preferable.

The solubility parameters of the (co)polymer (B) and (meth)acrylic resin (A) are specified by the Fedors formula. The Fedors formula is a calculation formula for calculating the SP value from cohesive energy density, molar volume (molar molecular volume), and the like. F. Fedors, "A Method for Estimating Both the Solubility Parameters and Molar Volumes of Liquids" (POLYMER ENGINEERING AND SCIENCE, February 1974, Vol. 14, No. 2, pp. 147-152). That is, the SP value calculated by the Fedors formula is a calculated value determined by the molecular structure of the compound.

The solubility parameter can be adjusted by the type, combination, ratio, etc. of the structural units constituting the (co)polymer (B).

(About other requirements)
The (co)polymer (B) preferably further satisfies the following (B-6).

(B-6) Containing structural units derived from an unsaturated aliphatic hydrocarbon compound having 4 or 5 carbon atoms in an amount of 10 mol% or more and 30 mol% or less based on the total amount of all structural units of the (co)polymer (B) .

When the (co) polymer (B) has a structural unit derived from an unsaturated aliphatic hydrocarbon compound having 4 or 5 carbon atoms, the (co) polymer (B) can be crosslinked, and the z average The molecular weight tends to fall within the above range.

On the other hand, when the amount of the structural unit derived from the unsaturated aliphatic hydrocarbon compound having 4 or 5 carbon atoms is 30 mol% or less, the amount of isopropyltoluene in the (co)polymer (B) is sufficiently increased, As described above, the transparency of the adhesive composition is improved.

Examples of unsaturated aliphatic hydrocarbon compounds having 4 or 5 carbon atoms include _C4 fractions containing as a main component unsaturated aliphatic hydrocarbon compounds having 4 or 5 carbon atoms, which are by-produced during petroleum refining and cracking. and _C5 fractions, etc.

The above _C4 fraction and _C5 fraction are fractions having a boiling point range of usually -15 to +45°C under normal pressure. The _C4 and _C5 fractions are 1-butene, isobutene, 2-butene, 1,3-butadiene, 1-pentene, 2-methyl-1-butene, 3-methyl-1-butene, 2- It includes unsaturated aliphatic hydrocarbon compounds such as pentene, isoprene, 1,3-pentadiene, and cyclopentadiene.

The above _C4 fraction and _C5 fraction are light oil fractions including gas fractions by-produced during atmospheric distillation (topping) of crude oil in oil refineries, etc., by-products in the cracking or reforming process of petroleum. Petroleum fractions, including similar light oil fractions and light oil fractions containing gas obtained in petroleum naphtha cracking in petrochemical plants, etc., may be used as is, or may be subjected to distillation, extraction or other treatment. In addition, it may be used as a desired fraction.

The content of the structural unit derived from the unsaturated aliphatic hydrocarbon compound having 4 or 5 carbon atoms with respect to the total amount of the structural units of the (co)polymer (B) is more preferably 10 mol% or more and 30 mol% or less, 11 mol % or more and 25 mol % or less is more preferable, and 12 mol % or more and 20 mol % or less is particularly preferable.

(About other monomers)
The (co)polymer (B) may optionally contain structural units derived from monomers other than the isopropenyltoluene or the unsaturated hydrocarbon compound having 4 or 5 carbon atoms described above. When isopropenyl toluene and unsaturated hydrocarbon compounds having 4 or 5 carbon atoms are copolymerized with monomers other than these, the softening point and glass transition temperature (Tg) of the (co)polymer (B) can be adjusted. easier.

Examples of monomers other than the above include vinyl aromatic compounds and unsaturated aliphatic hydrocarbon compounds other than those having 4 or 5 carbon atoms.

Examples of the vinyl aromatic compound include styrenic monomers such as substituted styrene having a substituent on the aromatic ring and substituted α-methylstyrene having a substituent on the aromatic ring. Examples of substituents on the aromatic ring include alkyl groups having 1 to 20 carbon atoms, alkoxy groups having 1 to 20 carbon atoms, aryl groups having 6 to 20 carbon atoms, and halogen atoms. The vinyl aromatic compound may have one substituent on the aromatic ring, or two or more substituents on the aromatic ring.

Specific examples of the substituted styrene include methylstyrene (except α-methylstyrene), ethylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-tert-butylstyrene, pn-hexylstyrene. , pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, and 3,4-dichlorostyrene. including styrene.

(Synthesis method)
The (co)polymer (B) can be obtained by synthesizing isopropenyltoluene, an unsaturated hydrocarbon compound having 4 or 5 carbon atoms, and other monomers by a known polymerization method. The polymerization is preferably cationic polymerization, more preferably in the presence of a Friedel-Crafts catalyst.

The above Friedel-Crafts catalysts include aluminum chloride, aluminum bromide, dichloromonoethylaluminum, titanium tetrachloride, tin tetrachloride, boron trifluoride, and various complexes such as boron trifluoride ether complexes or phenol complexes. is not particularly limited as long as it is a known Friedel-Crafts catalyst including Among these, a phenol complex of boron trifluoride is preferred. The amount of the Friedel-Crafts catalyst used can be 0.05 parts by mass or more and 5 parts by mass or less with respect to a total of 100 parts by mass of the raw material monomers, and is 0.1 parts by mass or more and 2 parts by mass or less. is preferred.

The polymerization reaction is preferably carried out using a solvent so that the concentration of the raw material monomer is about 10 to 60% by mass, from the viewpoints of removing reaction heat generated during the polymerization reaction, suppressing the viscosity of the reaction liquid, adjusting the molecular weight, and the like. . Examples of such solvents include aliphatic hydrocarbons such as pentane, hexane, heptane, and octane; alicyclic hydrocarbons such as cyclopentane, cyclohexane, and methylcyclohexane; and toluene, xylene, ethylbenzene, and mesitylene. Aromatic hydrocarbons including; One of these solvents may be used alone, or two or more of them may be used in combination.

The polymerization can be carried out by polymerizing raw material monomers in the solvent in the presence of the catalyst in a reactor. The above polymerization can be carried out in one stage, but is preferably carried out in multiple stages. The polymerization temperature at this time varies depending on the raw material composition, the target molecular weight range, etc., but is preferably -50 to +50°C. Further, the reaction time at this time is preferably 10 minutes to 10 hours. After the polymerization is completed, the catalyst is decomposed using a basic aqueous solution or a basic compound containing an alcohol such as methanol, washed with water, and unreacted raw materials and solvents are stripped or distilled. Except for this, the desired (co)polymer (B) can be obtained.

The removal of the unreacted raw materials and solvents can be carried out, for example, by atmospheric distillation, reduced pressure distillation, steam distillation, etc., an operation of concentrating using the difference in vapor pressure of each substance, and an open column, a flash column, etc. It can be carried out by a method of concentrating using differences in affinity and molecular size for fillers such as silica gel. Among these, vacuum distillation is preferable from the viewpoint of thermal decomposition suppression and concentration efficiency. The range of pressure reduction is not particularly limited. On the other hand, from the viewpoint of suppressing thermal decomposition of the (co)polymer (B), the heating temperature is preferably 250° C. or lower, more preferably 230° C. or lower, and 210° C. or lower. More preferred.

[Crosslinking agent (C)]
The cross-linking agent (C) is not particularly limited as long as it can cross-link the (meth)acrylic resin (A) and further increase the adhesiveness of the adhesive composition of the present embodiment.

Examples of crosslinkers (C) include sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, glycerol polyglycidyl ether, neopentyl glycol diglycidyl ether, and resorcin diglycidyl ether. Epoxy compounds including ethers; isocyanate compounds including tetramethylene diisocyanate, hexamethylene diisocyanate, toluenediisocyanate triadduct of trimethylolpropane, and polyisocyanates; trimethylolpropane-tri-β-aziridinylpropionate , tetramethylolmethane-tri-β-aziridinylpropionate, N,N′-diphenylmethane-4,4′-bis(1-aziridinecarboxamide), N,N′-hexamethylene-1,6-bis (1-aziridinecarboxamide), N,N'-toluene-2,4-bis(1-aziridinecarboxamide), trimethylolpropane-tri-β-(2-methylaziridine)propionate, and other aziridine compounds; and melamine-based compounds including hexamethoxymethylolmelamine and the like. The cross-linking agent (C) may be used singly or in combination of two or more.

The cross-linking agent (C) has the number of functional groups capable of bonding with the (meth)acrylic resin (A) in the cross-linking agent (C) (when the cross-linking agent (C) contains blocked isocyanate, the number of functional groups generated by dissociation of the blocking agent ) is preferably blended to the extent that the number of functional groups does not exceed the number of functional groups possessed by the (meth)acrylic resin (A), but when new functional groups are generated by the cross-linking reaction or the progress of the cross-linking reaction is slow Occasionally, more than this value may be added.

[Content ratio]
The adhesive composition related to the present embodiment includes 47 parts by mass or more and 99 parts by mass or less of (meth)acrylic resin (A), 0.5 parts by mass or more and 50 parts by mass or less of (co)polymer (B), and It contains 0.5 parts by mass or more and 3 parts by mass or less of a cross-linking agent (C). However, the total content of (meth)acrylic resin (A), (co)polymer (B) and cross-linking agent (C) is 100 parts by mass.

When the content of the (meth)acrylic resin (A) is 47 parts by mass or more, a relatively large amount of the (meth)acrylic resin (A) is contained in the adhesive composition, and the adhesive composition easily forms a crosslinked structure. As a result, the pressure-sensitive adhesive composition has a high molecular weight, and the pressure-sensitive adhesiveness is less likely to decrease during lamination. On the other hand, when the content of the (meth)acrylic resin (A) is 99 parts by mass or less, sufficient amounts of the (co)polymer (B) and the cross-linking agent (C) are contained in the adhesive composition. will be Therefore, the adhesiveness of the adhesive composition tends to be good. The content of the (meth)acrylic resin (A) is preferably 57.2 parts by mass or more and 94 parts by mass or less, more preferably 62.5 parts by mass or more and 88.5 parts by mass or less.

When the content of the (co)polymer (B) is 0.5 parts by mass or more, the adhesiveness of the adhesive composition increases. On the other hand, when the content of the (co)polymer (B) is 50 parts by mass or less, the transparency of the adhesive composition is enhanced. From the above viewpoint, the content of the (co)polymer (B) is preferably 5 parts by mass or more and 40 parts by mass or less, more preferably 10 parts by mass or more and 35 parts by mass or less.

When the content of the cross-linking agent (C) is 0.5 parts by mass or more, the adhesive composition tends to be moderately aggregated, and the adhesive composition is applied to the surface of the adherend after peeling the adhesive composition. It is difficult for things to remain. When the content of the cross-linking agent (C) is 3 parts by mass or less, the (meth)acrylic resin (A) and the (co)polymer (B) are included in a sufficient amount, so the adhesiveness tends to be good. . The content of the cross-linking agent (C) is preferably 1 part by mass or more and 2.8 parts by mass or less, and more preferably 1.5 parts by mass or more and 2.5 parts by mass or less.

In addition, it is preferable that the adhesive composition regarding this embodiment does not substantially contain a rosin resin or a terpene resin. Rosin resins or terpene resins color or discolor the adhesive composition. Hydrogenated resins obtained by hydrogenating rosin resins or terpene resins are sometimes used in the adhesive composition in order to suppress the above-mentioned coloring, but these tend to reduce adhesive holding power. Furthermore, since the rosin resin or terpene resin has an acid value, the metal may be corroded when the adhesive composition containing these resins is applied to the metal.

Here, "substantially free" means that the content of the rosin resin or terpene resin is 0.1% by mass or less with respect to the total mass of the adhesive composition.

[Production method]
The adhesive composition according to the present embodiment contains the above-described (meth)acrylic resin (A), (co)polymer (B), and cross-linking agent (C) in an amount corresponding to the above-described content, and optionally can be prepared by mixing with the solvent used for

Examples of such solvents include ethyl acetate, butyl acetate, benzene, toluene, xylene, cyclohexane, methyl ethyl ketone, and the like.

[Use]
The adhesive composition according to the present embodiment can be used for various applications requiring adhesiveness as adhesive products such as tapes, labels, sheets and double-sided tapes.

Although the shape of the adhesive processed product is not particularly limited, it may have, for example, a structure comprising a substrate and an adhesive layer obtained from the adhesive composition. In addition, you may have a base material on both surfaces of the adhesion layer.

Although the thickness of the adhesive layer is not particularly limited, it is preferably 5 μm or more and 50 μm or less from the viewpoint of imparting desired adhesiveness to the adhesive processed product and reducing the impact on the productivity of the adhesive processed product. , 5 μm or more and 40 μm or less, and more preferably 10 μm or more and 30 μm or less. The adhesive composition described above can sufficiently exhibit adhesiveness even in a thin film. Therefore, even if the thickness of the adhesive layer is 30 μm or less, for example, sufficient adhesive force can be obtained.

Further, the type of substrate is not particularly limited, and may be a resin film or the like, or may be a metal film or the like. The shape of the substrate is also not particularly limited, and may be a flat plate shape or a three-dimensional structure, and is appropriately selected according to the application. Moreover, although the transparency is not particularly limited, the adhesive composition is excellent in transparency as described above. Therefore, it is possible to use the adhesive processed product for applications that require transparency, and in this case, it is preferable that the base material also has excellent transparency.

For example, when the adhesive processed product is required to have transparency, the total light transmittance of the adhesive processed product measured according to JIS K7361 is preferably 87% or more. In such applications, it is preferable to use a transparent PET film or the like as the substrate.

Further, when the adhesive processed product is attached to the adherend SUS through the adhesive layer, the adhesive strength measured by the 180 ° peel test is preferably 9 N / 25 mm or more, 10 N/25 mm or more is more preferable, and 10.5 N/25 mm or more is even more preferable.

The adhesive processed product can be produced by applying the adhesive composition to the surface of a substrate and drying the applied adhesive composition to crosslink each component.

The coating method is not particularly limited, and coating may be performed by a known method such as a roll coater method, a reverse roll coater method, a gravure roll method, a bar coater method, a comma coater method, and a die coater method. The drying conditions are also not particularly limited, and drying at 80 to 200° C. for 10 seconds to 10 minutes is preferable, and drying at 80 to 170° C. for 15 seconds to 5 minutes is more preferable.

EXAMPLES The present invention will be described below using examples and comparative examples, but the present invention is not limited to the following examples.

[Measurement of physical properties]
<Structural unit content>
The structural unit content (mol%) of the (co)polymers (B1) to (B8) was obtained by analysis of ¹³ C-NMR spectra measured under the following conditions.
Apparatus: Bruker Biospin AVANCE III cryo-500 type nuclear magnetic resonance apparatus Measurement nucleus: ¹³ C (125 MHz)
Measurement mode: Single pulse proton broadband decoupling Pulse width: 45° (5.00 μs)
Points: 64k
Measurement range: 250 ppm (-55 to 195 ppm)
Repeat time: 5.5 seconds Accumulation times: 128 times Measurement solvent: ortho-dichlorobenzene/benzene-d ₆ (4/1 (volume ratio))
Sample concentration: 60mg/0.6mL
Measurement temperature: 120°C
Window function: exponential (BF: 1.0Hz)
Chemical shift standard: δδ signal 29.73 ppm

<Softening point>
The softening points of the (co)polymers (B1) to (co)polymers (B8) were measured by the ring and ball method according to JIS K2207.

<Glass transition temperature (Tg)>
The glass transition temperatures (Tg) of the (meth)acrylic resin (A) and the (co)polymers (B1) to (co)polymers (B8) were measured by enclosing these resins in a simple closed pan, under a stream of nitrogen, The DSC curve when the temperature was raised from −100° C. to 200° C. at a rate of 10° C./min was analyzed according to JIS K7121.

<Number average molecular weight (Mn), z average molecular weight (Mz), weight average molecular weight (Mw/Mn), and content of compounds having a molecular weight of 400 or less>
Number average molecular weight (Mn), weight average molecular weight (Mw), z average molecular weight (Mz) and molecular weight distribution of (meth)acrylic resin (A) and (co)polymer (B1) to (co)polymer (B8) (Mw/Mn) was obtained from GPC measurement. Measurement was performed under the following conditions. Then, the number average molecular weight (Mn), weight average molecular weight (Mw), and z average molecular weight (Mz) were obtained from a calibration curve using commercially available monodisperse standard polystyrene, and Mw/Mn was calculated.
Apparatus: GPC HLC-8320 (manufactured by Tosoh Corporation)
Solvent: Tetrahydrofuran Column: TSKgel G7000×1, TSKgel G4000×2, TSKgel G2000×1 (both manufactured by Tosoh Corporation)
Flow rate: 1.0 ml/min Sample: 20 mg/mL tetrahydrofuran solution Temperature: 40°C

<Solubility parameter (SP value)>
The solubility parameters of (co)polymer (B1) to (co)polymer (B8) were calculated from the Fedors formula. The Fedors formula is a calculation formula for calculating the SP value from cohesive energy density, molar volume (molar molecular volume), and the like. F. Fedors, "A Method for Estimating Both the Solubility Parameters and Molar Volumes of Liquids" (POLYMER ENGINEERING AND SCIENCE, February 1974, Vol. 14, No. 2, pp. 147-152). That is, the SP value calculated by the Fedors formula is a calculated value determined by the molecular structure of the compound.

[Synthesis of (meth)acrylic resin (A)]
A (meth)acrylic resin (A) was synthesized using the following monomers.

2-ethylhexyl acrylate (2EHA)
Ethyl acrylate (EA)
vinyl acetate (VA)
Acrylic acid (AA)
Hydroxyethyl acrylate (HEA)

(Synthesis of (meth)acrylic resin (A1))
A temperature-controllable reactor equipped with a stirrer was charged with 350 parts by mass of ethyl acetate as a polymerization solvent and 40 parts by mass of toluene, and the mixture was purged with nitrogen and heated. After heating to 75 ° C., 316 parts by weight of 2EHA, 43 parts by weight of EA, 50 parts by weight of VA, 9 parts by weight of AA, 2 parts by weight of HEA, and 2 parts by weight as a polymerization initiator were added to the reactor. A mixed solution of 1 part of benzoyl peroxide was continuously added and allowed to react for 5 hours. After 5 hours, the mixture was diluted with 120 parts by mass of toluene to obtain an ethyl acetate/toluene solution containing (meth)acrylic resin (A1) with a solid content of 45%.

The glass transition temperature (Tg) of the (meth)acrylic resin (A1) obtained by evaporating the solvent from the obtained solution was measured and found to be -60°C.

[Synthesis of (co)polymer (B)]
(Co)polymers (B1) to (co)polymers (B8) were prepared as follows. Table 1 shows the composition, softening point, glass transition temperature (Tg), number average molecular weight (Mn), z average molecular weight (Mz), dispersity which is the ratio of weight average molecular weight (Mw) to number average molecular weight (Mn). (Mw/Mn), and solubility parameters. In Table 1, "IPT" represents isopropenyltoluene, and _C5 represents a _C5 fraction obtained by thermal decomposition of petroleum naphtha. The _C5 fraction mainly contains C5 unsaturated aliphatic hydrocarbon compounds.

(Synthesis of (co)polymer (B1))
A mixture of isopropenyl toluene, a _C5 fraction obtained by pyrolysis of petroleum naphtha and dehydrated toluene (sum of monomers/toluene = 1/1 ( (volume ratio)) and a boron trifluoride phenolate complex (1.7 equivalents of phenol) diluted 10 times with dehydrated toluene were continuously supplied to carry out a polymerization reaction at 5°C. The mass ratio of isopropenyltoluene to the _C5 fraction (isopropenyltoluene/ _C5 fraction) was 71/29, the feed rate of the mixture of monomer and toluene was 1.0 l/h, the feed rate of diluted catalyst was 116 ml/hour.

The reaction mixture was transferred to the second autoclave and allowed to continue the polymerization reaction at 5°C. Then, when the total residence time in the first and second autoclaves reached 2 hours, the reaction mixture was continuously discharged from the autoclave, and when the residence time reached 3 times, 1 liter of The reaction mixture was sampled to terminate the polymerization reaction. After the polymerization was completed, a 1 N NaOH aqueous solution was added to the sampled reaction mixture to deash the catalyst residue. Furthermore, after washing the obtained reaction mixture five times with a large amount of water, the solvent and unreacted monomers were distilled off under reduced pressure using an evaporator to obtain a copolymer of isopropenyl toluene/ _C5 fraction (co) A polymer (B1) was obtained. The (co)polymer (B1) has a structural unit content derived from isopropenyltoluene of 87 mol%, a softening point of 95°C, a glass transition temperature (Tg) of 42°C, and a number average molecular weight (Mn) of 890. , the z-average molecular weight (Mz) is 2120, the dispersity (Mw/Mn), which is the ratio of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn), is 1.55, and the solubility parameter is 9.77 ( cal/cm ³ ) ^1/2 .

(Synthesis of (co)polymer (B2))
_The (co)polymer ( _B1 A (co)polymer (B2), which is a copolymer of isopropenyltoluene/ _C5 fraction, was obtained in the same manner as in the synthesis of ). The (co)polymer (B2) has a content of structural units derived from isopropenyltoluene of 88 mol%, a softening point of 105°C, a glass transition temperature (Tg) of 50°C, and a number average molecular weight (Mn) of 1050. , the z-average molecular weight (Mz) is 2380, the dispersity (Mw/Mn), which is the ratio of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn), is 1.54, and the solubility parameter is 9.78 ( cal/cm ³ ) ^1/2 .

(Synthesis of (co)polymer (B3))
_The (co)polymer ( _B1 A (co)polymer (B3), which is a copolymer of isopropenyltoluene/ _C5 fraction, was obtained in the same manner as in the synthesis of ). The (co)polymer (B3) has a structural unit content derived from isopropenyltoluene of 96 mol%, a softening point of 97°C, a glass transition temperature (Tg) of 41°C, and a number average molecular weight (Mn) of 710. , the z-average molecular weight (Mz) is 1510, the dispersity (Mw/Mn), which is the ratio of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn), is 1.45, and the solubility parameter is 9.86 ( cal/cm ³ ) ^1/2 .

(Synthesis of (co)polymer (B4))
_The (co)polymer ( _B1 A (co)polymer (B4), which is a copolymer of isopropenyltoluene/ _C5 fraction, was obtained in the same manner as in the synthesis of ). The (co)polymer (B4) has a structural unit content derived from isopropenyltoluene of 96 mol%, a softening point of 124°C, a glass transition temperature (Tg) of 62°C, and a number average molecular weight (Mn) of 1,140. , the z-average molecular weight (Mz) is 3100, the dispersity (Mw/Mn), which is the ratio of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn), is 1.74, and the solubility parameter is 9.86 ( cal/cm ³ ) ^1/2 .

(Synthesis of polymer (B5))
_Isopropenyl A (co)polymer (B5), which is a homopolymer of toluene, was obtained. The (co)polymer (B5) has a content of structural units derived from isopropenyltoluene of 100 mol%, a softening point of 100°C, a glass transition temperature (Tg) of 45°C, and a number average molecular weight (Mn) of 760. , the z-average molecular weight (Mz) is 1700, the dispersity (Mw/Mn), which is the ratio of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn), is 1.50, and the solubility parameter is 9.90 ( cal/cm ³ ) ^1/2 .

(Synthesis of (co)polymer (B6))
The (co)polymer (B6), which is a homopolymer of isopropenyltoluene, was prepared in the same manner as in the synthesis of the (co)polymer (B5), except that the diluted catalyst was supplied in an amount of 82 ml/hour. Obtained. The (co)polymer (B6) has a structural unit content derived from isopropenyltoluene of 100 mol%, a softening point of 118°C, a glass transition temperature (Tg) of 62°C, and a number average molecular weight (Mn) of 980. , the z-average molecular weight (Mz) is 2910, the dispersity (Mw/Mn), which is the ratio of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn), is 1.80, and the solubility parameter is 9.90 ( cal/cm ³ ) ^1/2 .

(Synthesis of (co)polymer (B7))
(Co)polymer (B7), which is a homopolymer of isopropenyltoluene, was prepared in the same manner as the synthesis of (co)polymer (B5), except that the amount of diluted catalyst supplied was 68 ml/hour. Obtained. The (co)polymer (B7) has a structural unit content derived from isopropenyltoluene of 100 mol%, a softening point of 133°C, a glass transition temperature (Tg) of 72°C, and a number average molecular weight (Mn) of 1110. , the z-average molecular weight (Mz) is 3510, the dispersity (Mw/Mn), which is the ratio of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn), is 1.89, and the solubility parameter is 9.90 ( cal/cm ³ ) ^1/2 .

(Synthesis of (co)polymer (B8))
The (co)polymer (B8), which is a homopolymer of isopropenyltoluene, was prepared in the same manner as in the synthesis of the (co)polymer (B5), except that the diluted catalyst was supplied in an amount of 53 ml/hour. Obtained. The (co)polymer (B8) has a content of structural units derived from isopropenyltoluene of 100 mol%, a softening point of 145°C, a glass transition temperature (Tg) of 78°C, and a number average molecular weight (Mn) of 1520. , the z-average molecular weight (Mz) is 4740, the dispersity (Mw/Mn), which is the ratio of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn), is 1.99, and the solubility parameter is 9.90 ( cal/cm ³ ) ^1/2 .

[Crosslinking agent (C)]
As the cross-linking agent (C1), Takenate D-101E manufactured by Mitsui Chemicals, Inc. (an isocyanate-based compound, “Takenate” is a registered trademark of the same company) was used.

[Preparation and Evaluation of Adhesive Processed Goods]
An ethyl acetate/toluene solution containing the (meth)acrylic resin (A1), any one of the (co)polymers (B1) to (co)polymers (B8), and a cross-linking agent (C) in a solution. The ratio of the (meth)acrylic resin (A1) and (co)polymer (B1) to (co)polymer (B8) contained in the cross-linking agent (C) is the mass ratio shown in Table 2. were mixed at room temperature to obtain an ethyl acetate/toluene solution of the adhesive composition.

The resulting ethyl acetate/toluene solution of the adhesive composition was applied to a release paper so that the film thickness after drying was 10 to 50 μm, dried at 100° C. for 10 minutes, and then a 25 μm PET film was applied to the coated surface. A pressure-sensitive adhesive sheet was produced by pressure bonding. The pressure-sensitive adhesive composition was sufficiently crosslinked by allowing it to stand at 50°C for 3 days.

<Measurement of total light transmittance>
The release paper of the adhesive sheet having a thickness of 50 μm was peeled off to expose the adhesive layer, and a PET film having a thickness of 25 μm was pressed against the exposed adhesive layer to obtain a test piece. The configuration of the test piece was PET film/adhesive layer/PET film=25 μm/50 μm/25 μm. Then, the total light transmittance of the test piece was measured according to JIS K7361.

<Measurement of adhesive strength>
The pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer with a film thickness of 30 μm was cut to a width of 25 mm and a length of 150 mm to obtain a test piece. The release paper of the test piece is peeled off to expose the adhesive layer, the exposed adhesive layer is brought into contact with a stainless steel plate (SUS) in an atmosphere of 23 ° C., and a 2 kg mass rubber roll is reciprocated twice to perform the test. The piece was crimped. After being left for 20 minutes, the 180° peel strength was measured at a speed of 300 mm/min according to JIS Z0237.

Table 2 shows the formulation of the adhesive composition constituting the produced adhesive processed product, the total light transmittance of the adhesive processed product, and the adhesive strength of the adhesive layer. Further, FIG. 1 shows the relationship between the total light transmittance and adhesive strength of Examples 1 and 2 and Comparative Examples 1-7.

As shown in Table 2 and FIG. 1, adhesive compositions (Examples 1 and 2) containing a (co)polymer (B) satisfying all requirements (B-1) to (B-5) are (B-1) to (B-5) than the adhesive composition containing the (co)polymer (B) (Comparative Examples 2 to 7), both adhesive strength and transparency was getting higher. Moreover, when the (co)polymer (B) was not contained (Comparative Example 1), the adhesive strength was very low.

ADVANTAGE OF THE INVENTION According to this invention, the adhesive composition with both high transparency and adhesiveness is provided. INDUSTRIAL APPLICABILITY The present invention can be suitably practiced in various applications that particularly require transparency of the adhesive composition.

Claims (6)

47 parts by mass or more and 99 parts by mass or less (meth)acrylic resin (A);
0.5 parts by mass or more and 50 parts by mass or less of a (co)polymer (B) different from the (meth)acrylic resin (A);
0.5 parts by mass or more and 3 parts by mass or less of a cross-linking agent (C);
(where the total content of (meth)acrylic resin (A), (co)polymer (B), and cross-linking agent (C) is 100 parts by mass),
The (meth)acrylic resin (A) satisfies the following requirements (A-1) and (A-2), and
The (co)polymer (B) satisfies all of the following requirements (B-1) to (B-5):
sticky composition.
(A-1) It contains a structural unit derived from a (meth)acrylate having an alkyl group having 1 to 12 carbon atoms and a structural unit derived from a (meth)acrylate containing a hydroxyl group.
(A-2) The glass transition temperature (Tg) measured by a differential scanning calorimeter (DSC) is in the range of -80°C or higher and 0°C or lower.
(B-1) Structural units derived from isopropenyltoluene are contained in an amount of 20 mol% or more based on the total amount of structural units of the (co)polymer (B).
(B-2) The softening point measured according to JIS K2207 is in the range of 80°C or higher and 120°C or lower.
(B-3) The glass transition temperature (Tg) measured by a differential scanning calorimeter (DSC) is in the range of 30°C or higher and 70°C or lower.
(B-4) The polystyrene-equivalent number-average molecular weight (Mn) measured by gel permeation chromatography (GPC) is in the range of 750 or more and 1200 or less, and the z-average molecular weight (Mz) is in the range of 2000 or more and 3000 or less. and the dispersity (Mw/Mn), which is the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn), is 1.5 or more and 1.8 or less.
(B-5) The solubility parameter is 9.80 (cal/cm ³ ) ^1/2 or less. The (co)polymer (B) satisfies the following requirements (B-6):
The adhesive composition of Claim 1.
(B-6) 10 mol% or more and 30 mol% or less of structural units derived from an unsaturated aliphatic hydrocarbon compound having 4 or 5 carbon atoms relative to the total amount of all structural units of the (co)polymer (B); include. Having an adhesive layer obtained from the adhesive composition according to claim 1 or 2,
being a tape, label, sheet or double-sided tape,
Adhesive artefact. The adhesive layer has a thickness of 5 μm or more and 50 μm or less,
The adhesive processed product according to claim 3. The total light transmittance measured in accordance with JIS K7361 is 87% or more,
The adhesive processed product according to claim 3 or 4. When attached to the adherend SUS via the adhesive layer, the adhesive strength measured by a 180 ° peel test is 10 N / 25 mm or more.
The adhesive processed product according to any one of claims 3-5.

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