JP7066084B1 - UV curable pressure-sensitive adhesive composition, and pressure-sensitive adhesive sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure-sensitive adhesive and a pressure-sensitive adhesive sheet which exhibit high adhesive strength to both a high-polarity adherend and a low-polarity adherend even if they are thin films, and also have excellent holding power and curved surface adhesiveness. thing. A monomer unit containing a copolymer (A) having an ultraviolet reactive group, the copolymer (A) having a weight average molecular weight of 400,000 to 1.5 million, and having an alkyl group. (A1), a copolymer having a monomer unit having a carboxyl group (a2), a monomer unit having an ultraviolet reactive group (a3), and the monomer unit having a carboxyl group (a2) is It is solved by an ultraviolet curable pressure-sensitive adhesive composition having at least one of (a2-1) represented by the general formula (1) and (a2-2) represented by the general formula (2). To. [Selection diagram] None

Description

The present invention relates to an ultraviolet curable pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet.

The pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition is used in a wide range of fields as a label and an adhesive application because it is easy to handle. In recent years, there has been a demand for thinning of the adhesive layer for various purposes from the viewpoint of cost reduction and reduction of environmental load, and from the viewpoint of reducing the weight and thinning of electronic devices. However, the adhesive strength of the pressure-sensitive adhesive sheet generally decreases as the film thickness of the pressure-sensitive adhesive layer decreases. Therefore, there is a strong demand for the development of an adhesive sheet having high adhesive strength even under thin film conditions. Furthermore, for use in various applications, it exhibits strong adhesive strength to both high-polarity adherends such as stainless steel plates and low-polarity adherends such as polyolefins, and also has holding power and curved surface adhesiveness. It is also necessary to be excellent.

On the other hand, in recent years, the development of adhesives using a cross-linking reaction with ultraviolet rays has been active, and the development is being promoted for various purposes. However, until now, the focus has been mainly on improving the cohesive force by improving the crosslink density after UV irradiation, and the adhesive force has often been sacrificed.
As an ultraviolet curable pressure-sensitive adhesive composition, Patent Document 1 contains a radically polymerizable diluent, an acrylic polymer, and a chlorinated polyolefin in a predetermined amount, thereby exhibiting a strong adhesive force to a low-polarity adherend. Sheets are proposed.
Patent Document 2 discloses an ultraviolet curable pressure-sensitive adhesive sheet containing a copolymer having two types of ultraviolet-reactive groups in the side chain and a high-concentration pressure-sensitive adhesive resin.

Japanese Unexamined Patent Publication No. 2012-031358 Special Table 2016-501290 Gazette

However, with these conventional pressure-sensitive adhesive sheets, it is difficult to achieve both adhesive strength and cohesive strength after irradiation with ultraviolet rays, and the adhesive strength is not sufficient for either high-polarity adherends or low-polarity adherends, especially under thin film conditions. .. In addition, the holding power and curved surface adhesiveness cannot be satisfied at present.

INDUSTRIAL APPLICABILITY The present invention is an ultraviolet curable pressure-sensitive adhesive composition which exhibits high adhesive strength to both high-polarity adherends and low-polarity adherends even if it is a thin film, and also has excellent holding power and curved surface adhesiveness. , And the purpose of providing an adhesive sheet.

（一般式（１）中、Ｒ_１１は、水素原子またはメチル基、ｍは２～１０の整数、ｎは１～５の整数を示す。）

（一般式（２）中、Ｒ_２１は、水素原子またはメチル基、Ｒ_３は二価の炭化水素基、ｐは１～５の整数を示す。） The ultraviolet curable pressure-sensitive adhesive composition of the present invention contains a copolymer (A) having an ultraviolet reactive group, and the copolymer (A) has a weight average molecular weight of 400,000 to 1.5 million and has a weight average molecular weight of 400,000 to 1.5 million. A copolymer having a monomer unit (a1) having an alkyl group, a monomer unit (a2) having a carboxyl group, and a monomer unit (a3) having an ultraviolet reactive group, and having a carboxyl group. The monomer unit (a2) is characterized by having at least one of (a2-1) represented by the following general formula (1) and (a2-2) represented by the following general formula (2). And.

(In the general formula (1), R ₁₁ is a hydrogen atom or a methyl group, m is an integer of 2 to 10, and n is an integer of 1 to 5.)

(In the general formula (2), R ₂₁ is a hydrogen atom or a methyl group, R ₃ is a divalent hydrocarbon group, and p is an integer of 1 to 5.)

INDUSTRIAL APPLICABILITY According to the present invention, an ultraviolet curable pressure-sensitive adhesive composition which exhibits high adhesive strength to both high-polarity adherends and low-polarity adherends even if it is a thin film, and also has excellent holding power and curved surface adhesiveness. , And an adhesive sheet can be provided.

Before describing the present invention in detail, terms are defined. First, sheet, film and tape are synonyms. "(Meta) acrylic", "(meth) acrylate", "(meth) acryloyl" and the like shall mean "acrylic or methacrylic", "acrylate or methacrylate", "acryloyl or methacryloyl" and the like, for example, "((meth) acrylic", "(meth) acrylate", "(meth) acryloyl" and the like. "Meta) Acrylic acid" means "acrylic acid or methacrylic acid". In addition, each of the monomers means an ethylenically unsaturated group-containing compound. The monomer after polymerization is called a monomer unit, and the monomer before polymerization is called a monomer. The adherend is the other party to which the adhesive sheet is attached.
In the present specification, the monomer unit having an alkyl group (a1), the monomer unit having a carboxyl group (a2), the monomer unit having an ultraviolet reactive group (a3), and the general formula (1). The monomer unit (a2-1) represented by the above and the monomer unit (a2-2) represented by the general formula (2) are the monomer unit (a1) and the monomer unit (a2), respectively. , Monomer unit (a3), monomer unit (a2-1), and monomer unit (a2-2).
Unless otherwise specified, the various components appearing in the present specification may be used independently or in combination of two or more.

（一般式（１）中、Ｒ_１１は、水素原子またはメチル基、ｍは２～１０の整数、ｎは１～５の整数を示す。）

（一般式（２）中、Ｒ_２１は、水素原子またはメチル基、Ｒ_３は二価の炭化水素基、ｐは１～５の整数を示す。） << UV curable adhesive composition >>
The pressure-sensitive adhesive composition of the present invention contains a copolymer (A) having an ultraviolet reactive group, and the copolymer (A) has a weight average molecular weight of 400,000 to 1.5 million and has an alkyl group. A copolymer having a monomer unit (a1), a monomer unit having a carboxyl group (a2), and a monomer unit having an ultraviolet reactive group (a3), and having a carboxyl group. (A2) has at least one of (a2-1) represented by the following general formula (1) and (a2-2) represented by the following general formula (2).

(In the general formula (1), R ₁₁ is a hydrogen atom or a methyl group, m is an integer of 2 to 10, and n is an integer of 1 to 5.)

(In the general formula (2), R ₂₁ is a hydrogen atom or a methyl group, R ₃ is a divalent hydrocarbon group, and p is an integer of 1 to 5.)

According to the above invention, the copolymer having an ultraviolet reactive group further has a monomer unit having a carboxyl group represented by the general formula (1) or (2), and is designed to have an appropriate molecular weight. This makes it possible to impart flexibility to the copolymer while maintaining the cohesive force after irradiation with ultraviolet rays. Therefore, although it is a thin film, it exhibits high adhesive strength to both high-polarity adherends and low-polarity adherends, and can also achieve holding power and curved surface adhesiveness. In addition, when a tackifier resin is used, the adhesiveness with the low-polarity adherend can be further improved due to the appropriate compatibility with the tackifier resin, and the adhesive strength can be further improved. ..

In addition to the copolymer (A), the pressure-sensitive adhesive composition of the present invention may use an organic solvent, a tackifier resin, a polyolefin, a photoinitiator, a polymerization inhibitor, or the like, if necessary.
It is preferable to include an organic solvent because the drying property and the coatability can be further improved. Further, it is preferable to include the tackifier resin and the polyofin in order to further improve the adhesion to the low-polarity adherend.

<Copolymer (A)>
The copolymer (A) has a weight average molecular weight of 400,000 to 1.5 million, and has a monomer unit (a1) having an alkyl group, a monomer unit (a2) having a carboxyl group, and UV reactivity. It is a copolymer having a monomer unit (a3) having a group as an essential unit and optionally having other monomer units as needed.
The monomer unit (a2) having a carboxyl group is a monomer unit represented by the following general formula (1) (a2-1) and a monomer unit represented by the following general formula (2). It has at least one of (a2-2).
The pressure-sensitive adhesive composition of the present invention is characterized by containing at least the copolymer (A), and the copolymer (A) itself may be used as the pressure-sensitive adhesive.

The weight average molecular weight is more preferably 500,000 to 1.3 million, and even more preferably 600,000 to 1.2 million. By setting Mw in the range of 400,000 to 1.5 million, it is possible to make excellent adhesive strength, holding power, and curved surface adhesiveness.
In the present invention, the weight average molecular weight is a polystyrene-equivalent value measured by gel permeation chromatography (GPC).

The molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) of the copolymer (A) is preferably 3.0 to 8.0, more preferably 4.0 to 8.0, and 4.0. ~ 7.0 is more preferable. By setting the molecular weight distribution in the range of 3.0 to 8.0, it becomes easy to satisfy all of the adhesive force, the holding force, and the curved surface adhesiveness.

The acid value of the copolymer (A) is preferably 0.1 to 24.0 mgKOH / g, more preferably 0.2 to 20.0 mgKOH / g. When the acid value of the copolymer (A) is 0.1 to 24.0 mgKOH / g, the cohesive force and the flexibility of the pressure-sensitive adhesive layer can be imparted in a well-balanced manner, and the adhesive strength, holding power, and curved surface can be imparted. It becomes easier to satisfy all of the adhesiveness.

In the present specification, the content of each monomer unit is the mass% of the monomer that brings each monomer unit to the copolymer (A).

[Monomer unit (a1)]
The monomer unit (a1) is a monomer unit having an alkyl group, and is formed by polymerizing a monomer (a'1) having an alkyl group.
The monomer (a'1) is a monomer having an alkyl group having 4 to 7 carbon atoms (a'1-1) and a monomer having an alkyl group having 8 to 12 carbon atoms (a'1-1). 2), and other monomers having an alkyl group, the monomer (a'1) is a monomer having an alkyl group having 4 to 7 carbon atoms (a'1-1), and carbon. The inclusion of a monomer (a'1-2) having an alkyl group of several 8 to 12 provides both adhesive strength to a highly polar adherend and a low-polarity adherend, and compatibility with a tackifier resin. It is preferable from the viewpoint of.
The content of the monomer unit (a1) is preferably 60 to 99% by mass, more preferably 70 to 98% by mass in the total 100% by mass of the monomer units. By using 60 to 99% by mass, it becomes easier to achieve both adhesive strength, holding power, and curved adhesiveness.

The content ratio of the monomer unit (a1-1) having an alkyl group having 4 to 7 carbon atoms and the monomer (a1-2) having an alkyl group having 8 to 12 carbon atoms is (a1-) in terms of mass ratio. 1) / (a1-2) = 99/1 to 20/80 is preferable, 98/2 to 50/50 is more preferable, and 95/5 to 60/40 is even more preferable. By using this ratio, it is possible to achieve both adhesive strength against a highly polar adherend and adhesive strength against a low-polarity adherend, improve compatibility with the tackifying resin, and further improve the adhesive strength. Can be improved.

Examples of the monomer (a'1-1) having an alkyl group having 4 to 7 carbon atoms include n-butyl (meth) acrylate, isobutyl (meth) acrylate, and n-hexyl (meth) acrylate. .. Among these, n-butyl (meth) acrylate is preferable from the viewpoint of achieving both adhesive strength and holding power.

Examples of the monomer (a'1-2) having an alkyl group having 8 to 12 carbon atoms include 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, and n-nonyl. Examples thereof include (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, and dodecyl (meth) acrylate. Among these, 2-ethylhexyl (meth) acrylate is preferable from the viewpoint of achieving both adhesive strength and holding power.

Other monomers having an alkyl group include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-octadecyl (meth) acrylate and isooctadecyl ( Meta) acrylate and the like can be mentioned.
When a monomer having an alkyl group is used, the content thereof is preferably 0.1 to 20% by mass in 100% by mass of the monomer mixture.

（一般式（１）中、Ｒ_１１は、水素原子またはメチル基、ｍは２～１０の整数、ｎは１～５の整数を示す。）

（一般式（２）中、Ｒ_２１は、水素原子またはメチル基、Ｒ_３は二価の炭化水素基、ｐは１～５の整数を示す。） [Monomer unit (a2)]
The monomer unit (a2) is a monomer unit having a carboxyl group, and is represented by the monomer unit (a2-1) represented by the following general formula (1) and the following general formula (2). It has at least one of the monomer units (a2-2). Among them, it is preferable to have the monomer unit (a2-2) represented by the general formula (2) in terms of both high-polarity adherend and low-polarity adherend.

(In the general formula (1), R ₁₁ is a hydrogen atom or a methyl group, m is an integer of 2 to 10, and n is an integer of 1 to 5.)

(In the general formula (2), R ₂₁ is a hydrogen atom or a methyl group, R ₃ is a divalent hydrocarbon group, and p is an integer of 1 to 5.)

The monomer unit (a2) is at least one of the monomer (a'2-1) represented by the general formula (11) and the monomer (a'2-2) represented by the general formula (21). It is polymerized and formed using either one.

The content of the monomer unit (a2) is preferably 0.1 to 10% by mass, more preferably 0.2 to 8% by mass, based on 100% by mass of the total of the monomer units. When it is 0.1 to 10% by mass, it becomes easier to satisfy all of the adhesive force, the holding force, and the curved adhesiveness.

（一般式（１１）中、Ｒ_１は水素原子またはメチル基、ｍは２～１０の整数、ｎは１～５の整数を示す。） (Monomer unit (a2-1))
The monomer unit (a2-1) is a monomer unit represented by the general formula (1), and is formed by polymerizing the monomer (a'2-1) represented by the following general formula (11). It is a monomer unit to be formed.

(In the general formula (11), R ₁ is a hydrogen atom or a methyl group, m is an integer of 2 to 10, and n is an integer of 1 to 5.)

In the general formula (11), m represents an integer of 2 to 10. m is an integer of 2 to 10, preferably an integer of 2 to 8, and more preferably an integer of 3 to 5, from the viewpoint of the balance between the adhesive force, the holding force, and the adhesiveness to the curved surface. n represents an integer of 1 to 5. The n is an integer of 1 to 5, preferably an integer of 2 to 4, from the viewpoint of the balance between the adhesive force, the holding force, and the adhesiveness to the curved surface.

The monomer (a'2-1) may be produced by a conventional method or may be appropriately selected from commercially available monomers.
Examples of the monomer (a'2-1) include β-hydroxyethyl acrylate and ω-carboxypolycaprolactone mono (meth) acrylate. As these monomers, for example, those commercially available as trade names of "β-CEA" (manufactured by Daicel Ornex) and "Aronix M-5300" (manufactured by Toagosei Co., Ltd.) can be used.

（一般式（２１）中、Ｒ_２は水素原子またはメチル基、Ｒ_３は二価の炭化水素基、ｐは１～５の整数を示す。） (Monomer unit (a2-2))
The monomer unit (a2-2) is a monomer unit represented by the general formula (2), and is formed by polymerizing the monomer (a'2-2) represented by the following general formula (21). It is a monomer unit to be formed.

(In the general formula (21), R ₂ is a hydrogen atom or a methyl group, R ₃ is a divalent hydrocarbon group, and p is an integer of 1 to 5.)

In the general formula (21), p represents an integer of 1 to 5. p is an integer of 1 to 5, but preferably an integer of 1 to 3 from the viewpoint of achieving both adhesive strength, holding power, and curved surface adhesiveness. R ₃ represents a divalent hydrocarbon group.
Examples of the divalent hydrocarbon group include a saturated aliphatic hydrocarbon group such as an alkylene group, a saturated alicyclic hydrocarbon group such as a cycloalkylene group, an aromatic hydrocarbon group such as a phenylene group, and an unsaturated aliphatic hydrocarbon group. , Or unsaturated alicyclic hydrocarbon groups and the like.
Among these, a saturated aliphatic hydrocarbon group is preferable, an alkylene group is more preferable, and an alkylene group having 1 to 4 carbon atoms is further preferable, from the viewpoint of improving the adhesive strength by imparting flexibility.

The monomer (a'2-2) may be produced by a conventional method or may be appropriately selected from commercially available monomers.
Examples of the monomer (a'2-2) include 2- (meth) acryloyloxyethyl succinic acid, 2- (meth) acryloyloxyethyl fumaric acid, 2- (meth) acryloyloxyethyl phthalic acid and the like. .. These monomers are, for example, "light ester HO-MS", "HOA-MS (N)", "light acrylate HOA-HH (N)" and "HOA-MPL (N)" (manufactured by Kyoeisha Chemical Co., Ltd.). Commercially available products can be used as the trade name of.

Even if the monomer unit (a2) has a monomer unit (a2-1) and a monomer unit (a2-3) having a carboxyl group other than the monomer unit (a2-2). good.
The other monomer unit having a carboxyl group (a2-3) is a monomer unit formed by polymerizing another monomer having a carboxyl group (a'2-3), and is a monomer (a). Examples of '2 -3) include (meth) acrylic acid and the like.

By having the monomer unit (a2-1) or the monomer unit (a2-2) as the monomer unit (a2), the flexibility of the copolymer can be adjusted and the adhesive strength despite the thin film can be adjusted. The balance between the highly polar site derived from the terminal carboxylic acid and the hydrophobic site derived from the side chain of an appropriate length makes it excellent in compatibility with the tackifier resin, resulting in a highly polar adherend. Adhesion to each of the low-polarity adherends is improved, and it becomes possible to achieve both the adhesive strength of the high-polarity adherend and the low-polarity adherend.

It is preferable that the content of the monomer unit (a2-3) other than the monomer unit (a2-1) and the monomer unit (a2-2) is small, but the total mass of the monomer unit (a2) is 100 mass. In%, it is preferably 40% by mass or less, more preferably 30% by mass or less, and further preferably 20% by mass or less.
When it is 40% by mass or less, it is preferable because it is easy to achieve both a high-polarity adherend and a low-polarity adherend.

[Monomer unit (a3)]
The monomer unit (a3) is a monomer unit having an ultraviolet reactive group, and may be polymerized using the monomer (a'3) having an ultraviolet reactive group, or may be polymerized with a precursor. After synthesizing the copolymer (A'), an addition reaction may be carried out to introduce an ultraviolet reactive group.
The structure of the ultraviolet reactive group is not particularly limited, and an ethylenically unsaturated group or a benzophenone group is preferable, and since it has excellent ultraviolet reactivity and excellent curved surface adhesion of the pressure-sensitive adhesive layer after curing with ultraviolet rays, benzophenone is used. It is preferable to have a group.

Examples of the monomer having an ultraviolet reactive group (a'3) include a monomer having a benzophenone group, a monomer having a benzoin group, a monomer having a thioxanthone group and a maleimide group. Above all, a monomer having a benzophenone group is preferable because a crosslinked structure can be efficiently formed between the molecules of the copolymer (A) in an excited state by irradiation with ultraviolet rays. The ultraviolet reactive group may be contained alone or in combination of two or more in the molecule.

The monomer having a benzophenone group is, for example, 4-acryloyloxybenzophenone, 4-methacryloyloxybenzophenone, 2-hydroxy-4-acryloyloxybenzophenone, 2-hydroxy-4-methacryloyloxybenzophenone, 2-hydroxy-4- ( 2-Acryloyloxy) ethoxybenzophenone, 2-hydroxy-4- (2-methacryloyloxy) ethoxybenzophenone, 2-hydroxy-4- (2-methyl-2-acryloyloxy) ethoxybenzophenone, 2,2'-dihydroxy-4 -Examples include methacryloyloxybenzophenone. Of these, 4-acryloyloxybenzophenone and 4-methacryloyloxybenzophenone are preferable because of their UV reactivity and availability.

The method for introducing an ultraviolet reactive group by performing an addition reaction after synthesizing the copolymer (A') as a precursor is not particularly limited, and a conventionally known method can be appropriately selected according to the purpose. can.
For example, as a first step, a copolymer (A') having a monomer unit having a functional group such as a hydroxyl group, an epoxy group, or a carboxyl group is prepared, and then as a second step, the copolymer (A') is prepared. An ultraviolet reactive group can be introduced into the side chain of the copolymer by subjecting an addition reaction to a monomer having a functional group capable of reacting with a functional group such as a hydroxyl group, an epoxy group or a carboxyl group.
Specifically, method (i); copolymerization of a monomer having a hydroxyl group, a monomer (a'1), a monomer (a'2), and other monomers as needed. A monomer having an isocyanate group or the like is added to a part of the side chain hydroxyl group of the copolymer (A') obtained by the above-mentioned reaction, and the monomer having an ethylenically unsaturated group as an ultraviolet reactive group is subjected to an addition reaction. Method for obtaining a copolymer having a unit, method (ii); a monomer having an epoxy group, a monomer (a'1), a monomer (a'2), and other simple substances as required. A monomer having a carboxyl group is added to a part of the side chain epoxy group of the copolymer (A') obtained by copolymerizing with a polymer, and a monomer having a carboxyl group is subjected to an addition reaction to form an ethylenically unsaturated group as an ultraviolet reactive group. A method and method (iii) for obtaining a copolymer having a monomer unit having a group; a monomer (a'2) which is a monomer having a carboxyl group, a monomer (a'1), and the like. If necessary, a monomer having an epoxy group is added to a part of the side chain carboxyl groups of the copolymer (A') obtained by copolymerizing with other monomers, and a monomer having an epoxy group is subjected to an addition reaction to be UV-reactive. Examples thereof include a method for obtaining a copolymer having a monomer unit having an ethylenically unsaturated group.
In the case of the method (iii), the structural unit having a carboxyl group remaining without being used in the addition reaction with the epoxy group corresponds to the structural unit (a2) in the present specification. Therefore, in the copolymer (A) in the present invention, not all of the carboxyl groups of the monomer (a'2) undergo an addition reaction, and the monomer unit (a2-1) or the monomer is always present. The blending amount of the monomer (a'2) to be used and the monomer having an epoxy group is adjusted so as to have the unit (a2-2).

"Method (i)"
Examples of the monomer having a hydroxyl group used for constituting the copolymer (A') as a precursor include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 3-. Hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, acid 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) ) Hydroxyalkyl (meth) acrylates such as acrylates, polyethylene glycol mono (meth) acrylates, polypropylene glycol mono (meth) acrylic rates, glycol mono (meth) acrylates such as 1,4-cyclohexanedimethanol mono (meth) acrylates, And so on. Among these, 2-hydroxyethyl (meth) acrylate is preferable.

The monomer having an isocyanate group capable of reacting with a hydroxyl group is not particularly limited and may be appropriately selected depending on the intended purpose. For example, methacryloyloxyethyl isocyanate (MOI) and acryloyloxyethyl isocyanate (AOI). , Methacryloyloxyethyl isothiocyanate, acryloyloxyethyl isothiocyanate, methacryloylisothiocyanate, acryloylisothiocyanate, vinylisocyanate, allylisocyanate, (meth) acryloylisocyanate (MAI), isopropenyl-α, α-dimethylbenzylisocyanate (TMI), etc. Can be mentioned.

"Method (ii)"
Epoxy group-containing monomers used to form the precursor copolymer (A') include, for example, glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, and 3,4-epoxy. Cyclohexylmethyl (meth) acrylate and the like can be mentioned.

The monomer having a carboxyl group (a'2) capable of reacting with the epoxy group is not particularly limited, and is the same as the monomer exemplified in the above-mentioned monomer having a carboxyl group (a'2). Can be used.

"Method (iii)"
The monomer (a'2) having a carboxyl group used to form the copolymer (A') as a precursor is not particularly limited, and the above-mentioned monomer having a carboxyl group (a) is not particularly limited. The same monomers as those exemplified in '2) can be used.

The monomer having an epoxy group capable of reacting with the carboxyl group is not particularly limited, and the same monomer having an epoxy group described in the above method (ii) can be used.

The content of the monomer unit (a3) having an ultraviolet reactive group is preferably 0.01 to 5% by mass, preferably 0.01 to 1% by mass, in a total of 100% by mass of all the monomer units. % Is more preferable, and 0.02 to 0.6% by mass is further preferable. When it is 0.01% by mass or more, the adhesive strength and the holding power are more excellent, and when it is 5% by mass or less, more excellent curved surface adhesiveness can be exhibited.

[Other monomer units]
The copolymer (A) having an ultraviolet reactive group is a monomer unit having an alkyl group (a1), a monomer unit having a carboxyl group (a2), and a monomer unit having an ultraviolet reactive group (a1). In addition to a3), it may have other monomer units as needed.
The other monomer unit can have a pressure-sensitive adhesive composition within a range that does not impair the adhesive strength, holding power, and curved surface adhesiveness.
For example, a monomer unit having an aliphatic ring structure, a monomer unit having an aromatic ring, a monomer unit having an amide bond, a monomer unit having an epoxy group, a monomer unit having an amino group, Examples thereof include a monomer unit having an alkoxy (poly) alkylene oxide, and other vinyl monomer units. Among these, it is preferable to have a monomer unit having an aliphatic cyclic structure from the viewpoint of improving the adhesive strength to the low-polarity adherend and the compatibility with the tackifier resin.

Examples of the monomer having an alicyclic structure for forming a monomer unit having an alicyclic structure include cyclohexyl (meth) acrylate, dicyclopentanyl (meth) acrylate, and dicyclopentenyl. Examples include (meth) acrylate, isobornyl (meth) acrylate, 2-methyl-2-adamantyl (meth) acrylate, 2-ethyl-2-adamantyl (meth) acrylate, t-butylcyclohexyl (meth) acrylate, rosin acrylate and the like. Be done. Among these, dicyclopentenyl (meth) acrylate and dicyclopentanyl (meth) acrylate having a three-dimensional aliphatic cyclic structure from the viewpoint of improving the adhesive strength to the low-polarity adherend and the compatibility with the tackifier resin. , Isobornyl (meth) acrylate or rosin acrylate is preferred.
Examples of commercially available rosin acrylates include Beamset 101 (manufactured by Arakawa Chemical Industries, Ltd., 1-acrylic acid-3-dehydroabietic acid-2-hydroxypropyl).

Examples of the monomer having an aromatic ring for forming the monomer unit having an aromatic ring include phenoxyethyl (meth) acrylate, benzyl (meth) acrylate, phenoxydiethylene glycol (meth) acrylate, and ethylene oxide-modified nonylphenol. Examples thereof include (meth) acrylate.
When a monomer having an aromatic ring is used, the content of the monomer unit having an aromatic ring is preferably 0.1 to 10% by mass in a total of 100% by mass of the monomer units.

Examples of the monomer having an amide bond for forming a monomer unit having an amide bond include (meth) acrylamide, N-methylacrylamide, N-isopropylacrylamide, N, N-dimethylacrylamide, N, N. -(Meta) acrylamide compounds such as diethylacrylamide, N, N-dimethylaminopropyl (meth) acrylamide, diacetoneacrylamide, N- (butoxymethyl) acrylamide; N-vinylpyrrolidone, N-vinylcaprolactam, acryloylmorpholin and the like. Examples thereof include acrylamide-containing compounds.

The monomer having an epoxy group for forming the monomer unit having an epoxy group includes the monomer having an epoxy group exemplified in the description of the method (ii) of the monomer unit (a3). The same can be used.

Examples of the monomer having an amino group for forming a monomer unit having an amino group include monomethylaminoethyl (meth) acrylate, monoethylaminoethyl (meth) acrylate, and monomethylaminopropyl (meth) acrylate. And monoalkylamino (meth) acrylates such as monoethylaminopropyl (meth) acrylates and the like.

When a monomer having an amide bond, a monomer having an epoxy group, and a monomer having an amino group are used, the content thereof is 0.1 to 1 in 100% by mass of the total of the monomer units. It is preferably by mass%.

Examples of the monomer having an alkoxy (poly) alkylene oxide for forming a monomer unit having an alkoxy (poly) alkylene oxide include 2-methoxyethyl acrylate, 2-ethoxyethyl acrylate, and 2-phenoxyethyl acrylate. , Can be mentioned.
When a monomer having an alkoxy (poly) alkylene oxide is used, the content thereof is preferably 0.1 to 10% by mass in a total of 100% by mass of the monomer units.

As the monomer having a hydroxyl group for forming the monomer unit having a hydroxyl group, the same monomer as the monomer having a hydroxyl group exemplified in the explanation of the method (i) of the monomer unit (a3) is used. Can be used.
When a monomer having a hydroxyl group is used, the content thereof is preferably 0.1 to 1% by mass in a total of 100% by mass of the monomer units.

Other vinyl monomers for forming the vinyl monomer unit include, but are not limited to, styrene, vinyl acetate, acrylonitrile, and the like.
When other vinyl monomers are used, the content thereof is preferably 0.1 to 10% by mass in a total of 100% by mass of the monomer units.

[Manufacturing of copolymer (A)]
As a method for producing the copolymer (A), a method for copolymerizing a monomer mixture containing a monomer (a'1), a monomer (a'2), and a monomer (a'3). Or, a monomer (a'1), a monomer (a'2), and a monomer having a functional group as required, as exemplified in the above-mentioned methods (i) to (iii). After producing a copolymer (A') to be a precursor by copolymerizing a monomer mixture containing the same, it has another functional group capable of reacting with the functional group of the side chain of the copolymer (A'). Examples thereof include a method of introducing an ultraviolet reactive group by performing an addition reaction with a monomer.
The method of copolymerizing the monomer mixture is not particularly limited, and examples thereof include a method of adding a polymerization initiator to the monomer mixture and subjecting it to solution polymerization. The solvent used for the solution polymerization is, for example, methyl acetate, ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, xylene, hexane, acetone, methyl ethyl ketone, methyl isobutyl ketone, methanol, ethanol, n-propanol, isopropanol and the like. Is preferable, and ethyl acetate is more preferable.

For solution polymerization, it is preferable to add about 0.001 to 1 part by mass of a polymerization initiator to 100 parts by mass of the monomer mixture. Usually, the polymerization can be carried out under a nitrogen stream at a temperature of about 50 ° C. to 90 ° C. for 6 hours to 20 hours. Further, at the time of polymerization, the weight average molecular weight of the copolymer can be appropriately adjusted by using a chain transfer agent.

Chain transfer agents include, for example, n-dodecyl mercaptan, mercaptoisobutyl alcohol, mercaptoacetic acid, 2-mercaptoethanol, thioglycolic acid, 2-ethylhexyl thioglycolate, 2,3-dimercapto-1-propanol, glycidyl mercaptan, α-methylstyrene. Dimer, carbon tetrachloride, chloroform, hydroquinone and the like can be mentioned. As the chain transfer agent, about 0.01 to 1 part by mass can be used with respect to 100 parts by mass of the monomer mixture.

The polymerization initiator is generally an azo compound or an organic peroxide.
Examples of the azo compound include 2,2'-azobisisobutyronitrile, 2,2'-azobis (2-methylbutyronitrile), 1,1'-azobis (cyclohexane1-carbonitrile), 2,2. '-Azobis (2,4-dimethylvaleronitrile), 2,2'-Azobis (2,
4-Dimethyl-4-methoxyvaleronitrile), dimethyl 2,2'-azobis (2-methylpropionate), 4,4'-azobis (4-cyanovaleric acid), 2,2'-azobis (2) -Hydroxymethylpropionitrile), and 2,2'-azobis (2- (2- (2-)
Imidazoline-2-yl) propane) and the like.
Organic peroxides include, for example, benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di (2-ethoxyethyl) peroxydicarbonate. , T-Butylperoxyneodecanoate, t-Butylperoxyvivarate, (3,5,5-trimethylhexanoyl) peroxide, dipropionyl peroxide, diacetyl peroxide and the like.

<Organic solvent>
The pressure-sensitive adhesive composition of the present invention may further contain an organic solvent. By containing an organic solvent, the coatability can be further improved. In particular, even a pressure-sensitive adhesive composition containing a copolymer having a high molecular weight is preferable because it can be coated.
Examples of the organic solvent include methyl acetate, ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, xylene, hexane, acetone, methyl ethyl ketone, methyl isobutyl ketone, methanol, ethanol, n-propanol, isopropanol and the like.

When an organic solvent is used, the content of the organic solvent is preferably 80% by mass or less, preferably 70% by mass, based on 100% by mass of the pressure-sensitive adhesive composition, from the viewpoint of further improving the drying property and the coatability. The following is preferable. Further, it is preferably 10% by mass or more, and more preferably 20% by mass or more. In terms of environmental load, it is desirable that the content rate is low.

<Adhesive-imparting resin>
The pressure-sensitive adhesive composition of the present invention may further contain a pressure-sensitive adhesive resin. Examples of the pressure-sensitive adhesive composition include a rosin-based pressure-sensitive adhesive resin, a synthetic hydrocarbon-based pressure-sensitive adhesive resin, a terpene-based pressure-sensitive adhesive resin, a terpene phenol-based pressure-sensitive adhesive resin, and the like, among which rosin-based pressure-sensitive adhesive resin and synthetic hydrocarbon. It is preferable to contain at least one type of tackifier resin selected from the system-based tackifier resin and the terpene phenol-based tackifier resin. By including these adhesive-imparting resins, the adhesive strength can be further improved.
Furthermore, by using a rosin-based tackifier resin and a synthetic hydrocarbon-based tackifier resin in combination, it becomes easier to achieve both compatibility and adhesive strength to a highly polar adherend and a low-polarity adherend. preferable.
When the rosin-based tackifier resin and the synthetic hydrocarbon-based tackifier resin are used in combination, the content ratio thereof is not particularly limited, but the rosin-based tackifier resin / synthetic hydrocarbon-based tackifier resin = 0.1 to 5 is preferable. , 0.4 to 2.4 is more preferable, and 0.4 to 1 is even more preferable.

The rosin-based tackifier resin includes rosin esters obtained by esterifying unmodified rosins of gum rosin, tall oil rosin, and wood rosin with alcohol, and modified rosins such as disproportionated rosin modified from unmodified rosin, polymerized rosin, and hydrogenated rosin. , Disproportionate rosin ester obtained by further esterifying these modified rosins with alcohol or the like, modified rosin ester such as polymerized rosin ester or hydrogenated rosin ester, rosin phenol obtained by adding phenol to unmodified rosin, and the like are preferable. Among these, rosin ester and modified rosin ester are preferable because the adhesive strength and transparency are further improved. In the rosin ester and the modified rosin ester, some of the hydroxyl groups such as alcohol used for esterification may remain unreacted. Examples of the alcohol used for esterification include monofunctional alcohols such as methanol, bifunctional alcohols such as ethylene glycol, trifunctional alcohols such as glycerin, and tetrafunctional alcohols such as pentaerythritol, which are in phase with acrylic copolymers. Considering the solubility, alcohols having trifunctionality or less are preferable.

Examples of the synthetic hydrocarbon-based tackifier resin include a kumaron-based resin, a kumaron-inden-based resin, a styrene-based resin, a xylene-based resin, a phenol-based resin, and a petroleum-based resin. Among these, styrene-based resins are preferable because they have good compatibility with acrylic polymers and can further improve adhesive performance.

The pressure-sensitive adhesive resin used in the pressure-sensitive adhesive composition of the present invention includes a rosin-based pressure-sensitive adhesive resin and a synthetic hydrocarbon-based pressure-sensitive adhesive resin from the viewpoint of achieving both a high-polarity adherend and a low-polarity adherend. Is preferable, and a synthetic hydrocarbon-based tackifier resin is more preferable.

The softening point of the tackifier resin is preferably 80 ° C. or higher, more preferably 90 ° C. or higher. The upper limit of the softening point is preferably 170 ° C, more preferably 160 ° C, and even more preferably 155 ° C. When the softening point of the tackifying resin is 80 to 170 ° C., it becomes easy to achieve both adhesive strength and holding power at a high level. The softening point is the softening temperature measured according to the dry-bulb method specified in JIS K5902.

The tackifier resin is preferably used in an amount of 10 to 50 parts by mass, more preferably 15 to 40 parts by mass, based on 100 parts by mass of the copolymer (A). By using 10 to 50 parts by mass of the tackifying resin, the adhesive strength, the cohesive strength, and the curved surface adhesiveness can be improved.

<Polyolefin>
The pressure-sensitive adhesive composition of the present invention may further contain a polyolefin. By containing polyolefin, the adhesive strength to a low-polarity adherend made of polyolefin can be improved.

Polyolefins are classified into chlorinated polyolefins (hereinafter, chlorinated polyolefins) and non-chlorinated polyolefins (hereinafter, non-chlorinated polyolefins). Chlorinated polyolefins are, for example, chlorinated polypropylene and acids. Examples thereof include modified chlorinated polypropylene, acrylic modified chlorinated polypropylene, chlorinated polyethylene, chlorinated ethylene vinyl acetate copolymer and the like. Among these, chlorinated polypropylene, acid-modified chlorinated polypropylene, and acrylic-modified chlorinated polypropylene are preferable, and chlorinated polypropylene is more preferable, because they have excellent solubility and high adhesiveness to a polyolefin-made adherend.
The chlorine content of the chlorinated polyolefin is preferably 20% or more and 45% or less, and more preferably 28% or more and 45% or less, from the viewpoint of having a high effect of improving the adhesive strength on the low-polarity adherend made of polyolefin.

Examples of the non-chlorinated polyolefin include polyethylene, polypropylene, α-olefin-propylene copolymer, ethylene-vinyl acetate copolymer, polybutene, maleated polypropylene, maleated polybutene, polybutadiene and its hydride, polyisoprene and its hydride. Examples thereof include maleinated polybutadiene, maleated polyisoprene, polybutadiene polyol and its hydride, polyisoprene polyol and its hydride, and lubricating oil such as process oil and liquid paraffin.
Among these, α-olefin-polypropylene copolymer, maleated polypropylene, polybutene, and lubricating oil are preferable because of their excellent solubility and high adhesiveness to the polyolefin-made adherend. As the lubricating oil, paraffin-based lubricating oil, naphthen-based lubricating oil and the like are preferable.
As the polyolefin used in the pressure-sensitive adhesive composition of the present invention, chlorinated polyolefin is preferable from the viewpoint of excellent solubility and high adhesive strength to a polyolefin-made adherend, and chlorinated polypropylene is more preferable.

The polyolefin is preferably used in an amount of 0.01 to 10 parts by mass, more preferably 0.02 to 5 parts by mass with respect to 100 parts by mass of the copolymer (A). By using 0.01 to 10 parts by mass of polyolefin, it is possible to more easily achieve both adhesive force, cohesive force and curved surface adhesiveness to a low-polarity adherend.

The pressure-sensitive adhesive composition of the present invention further comprises, as optional components, a photoinitiator, a polymerization inhibitor, a curing agent, a monofunctional monomer, a polyfunctional monomer, a flame retardant aid, a heat-resistant stabilizer, and a weather-resistant stabilizer. It can include an antioxidant, an ultraviolet absorber, a leveling agent, an antioxidant, a slip agent, an antiblocking agent, an antifogging agent, a lubricant, a dye, a wax, an emulsion, a magnetic material, and a dielectric property modifier.

The pressure-sensitive adhesive composition of the present invention may contain an arbitrary photoinitiator, if necessary, for the purpose of improving photocurability and the like. For example, when the copolymer is cured by ultraviolet irradiation alone, such as an ultraviolet curable pressure-sensitive adhesive composition containing a copolymer having a benzophenone group as an ultraviolet reactive group, the use of a photoinitiator is optional. be.

Examples of photoinitiators include benzyldimethylketal, 1-hydroxycyclohexylphenylketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane-1-one, 2-hydroxy-2-. Methyl-1-phenylpropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butane-1-one, 1- [4- (2-hydroxyethoxy) -phenyl] -2-Hydroxy-2-methyl-1-propane-1-one, bisacylphosphine oxide, acylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,6-dimethylbenzoyldiphenylphosphine oxide, Benzoyldiethoxyphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, benzoin alkyl ether (eg, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, n -Butylbenzoyl ether, etc.), 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropane-1-one, 2-hydroxy-2-methyl-1-phenylpropane-1-one, p-tert- Butyltrichloroacetophenone, p-tert-butyldichloroacetophenone, benzyl, benzoyl, acetophenone, benzophenone, thioxanthones (2-chlorothioxanthone, 2-methylthioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone), dibenzos Beron, 4,4'-dichlorobenzophenone, 4,4'-bis (dimethylamino) benzophenone, 4,4'-bis (diethylamino) benzophenone, 3,3', 4,4'-tetra (tert-butylperoxy) Carbonyl) benzophenone, benzalacetone, biacetyl, α, α-dichloro-4-phenoxyacetophenone, tetramethylthium disulfide, α, α'-azobisisobutyronitrile, benzoylperoxide, 3,3'-dimethyl-4 -Methoxybenzophenone, methylbenzoylformate, 2,2-diethoxyacetophenone, asyloxime ester, chlorinated acetophenone, hydroxyacetophenone, acetophenone diethyl ketal, 4'-isopropyl- 2-Hydroxy-2-methylpropiophenone, methylphenylglycoxylate, methyl o-benzoylbenzoate, methyl p-dimethylaminobenzoate, 2,2'-bis (o-chlorophenyl) -4,5,4', 5'-tetraphenyl-1,2'-biimidazole, 10-butyl-2-chloroacryldone, camphorquinone, 3-ketocoumarin, anthraquinones (eg, anthraquinone, 2-ethylanthraquinone, α-chloroanthraquinone, 2) -Tart-butylanthraquinone, etc.), acenafsen, 4,4'-dimethoxybenzyl, 4,4'-dichlorobenzyl, etc. Commercially available examples of photoinitiators include those sold under the trade names of BASF's Irgacure and Omnirad, Merck's DaroCure, and Versicole's Versicure.

These photoinitiators may be used in combination with a sensitizer. The amount of the photoinitiator used is preferably 1 part by mass or less with respect to 100 parts by mass of the copolymer (A).

The pressure-sensitive adhesive composition of the present invention may contain any polymerization inhibitor. Examples of polymerization inhibitors include 3,5-bis-tert-butyl-4-hydroxytoluene, hydroquinone, methylhydroquinone, hydroquinone monomethyl ether (methquinone), p-tert-butylcatechol methoxyphenol, 2,6-di-. tert-butyl cresol, phenothiazine, tetramethylthium disulfide, diphenylamine, dinitrobenzene and the like can be used.

The pressure-sensitive adhesive composition of the present invention may contain any monofunctional monomer. The monofunctional monomer is not particularly limited, and is, for example, the above-mentioned monomer having an alkyl group (a'1), a monomer having a carboxyl group (a'2), and a monomer having an ultraviolet reactive group. The same monomers as those exemplified for the body (a'3) and other monomers can be used.

The pressure-sensitive adhesive composition of the present invention may contain any polyfunctional monomer. Examples of the polyfunctional monomer include 1,6-hexanediol di (meth) acrylate, 1,1 2-dodecanediol di (meth) acrylate, ethylene glycol di (meth) acrylate, and propylene glycol di (meth) acrylate. , Polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol di (meth) acrylate, allyl (meth) acrylate, vinyl (meth acrylate, divinylbenzene, etc.) Bifunctional monomer; Trimethylol propantri (meth) acrylate, pentaerythritol tri (meth) acrylate, tetramethylol methanetri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, etc. Monomers; Other examples include epoxy acrylates, polyester acrylates, urethane acrylates, and the like.

《Adhesive sheet》
The pressure-sensitive adhesive sheet has a pressure-sensitive adhesive layer obtained by curing a layer formed from the pressure-sensitive adhesive composition of the present invention with ultraviolet rays. The pressure-sensitive adhesive sheet preferably includes a base material and a pressure-sensitive adhesive layer. As another embodiment, a double-sided pressure-sensitive adhesive sheet having pressure-sensitive adhesive layers on both sides of the core material, or a cast pressure-sensitive adhesive sheet composed of only the pressure-sensitive adhesive layer without a base material and a core material is also preferable. The pressure-sensitive adhesive layer can be formed by applying a pressure-sensitive adhesive composition on a substrate, drying it, irradiating it with ultraviolet rays, and curing it with ultraviolet rays. Alternatively, it can be formed by applying the pressure-sensitive adhesive composition on a peelable sheet, drying it to form a pressure-sensitive adhesive layer, irradiating it with ultraviolet rays, curing it with ultraviolet rays, and laminating the base materials. It is usual to attach a peelable sheet to the surface of the pressure-sensitive adhesive layer that does not come into contact with the base material and store it.

When the pressure-sensitive adhesive composition is applied, the viscosity can be adjusted by adding the solvent described in solution polymerization.

As the base material, for example, cellophane, plastic, rubber, foam, cloth, rubberized cloth, resin-impregnated cloth, glass, wood and the like are preferable. The shape of the base material can be selected from a plate shape and a film shape, but a film shape that is easy to handle is preferable. As the base material, a single body or a laminated body of two or more kinds can be used.

The plastic may be, for example, a polyolefin such as polyvinyl alcohol, triacetyl cellulose, polypropylene, polyethylene, polycycloolefin, ethylene-vinyl acetate copolymer; polyester such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polycarbonate, polynorbornene. , Polyarylate, Polyacrylic, Polyphenylene sulfide, Polyester, Polyester, Polyester; and the like.

The method of applying the pressure-sensitive adhesive composition is not particularly limited, and for example, a Meyer bar, an applicator, a brush, a spray, a roller, a gravure coater, a die coater, a lip coater, a comma coater, a knife coater, a reverse coater, a spin coater, etc. Can be mentioned.
It is preferable to perform a drying step at the time of coating. The drying device is not particularly limited, and examples thereof include a hot air dryer, an infrared heater, and a decompression method. The drying temperature is usually about 60 to 160 ° C.

After coating the pressure-sensitive adhesive composition, the layer is irradiated with ultraviolet rays to obtain a pressure-sensitive adhesive layer which is a cured product of ultraviolet rays. Examples of the method of irradiating with ultraviolet rays include xenon lamps, xenon-mercury lamps, and metal halide lamps. Examples thereof include a method using a known ultraviolet light irradiation device such as a high-pressure mercury lamp and a low-pressure mercury lamp.

The integrated amount of ultraviolet rays is preferably in the range of 10 to 200 mJ / cm ² , more preferably 20 to 150 mJ / cm ² . The integrated amount of ultraviolet rays is based on a value measured in the wavelength range of UV-C using a UV checker "UV Power Pack II" manufactured by Heleus Co., Ltd.

The thickness of the pressure-sensitive adhesive layer is preferably 1 to 20 μm, more preferably 1 to 15 μm, and even more preferably 3 to 10 μm. By using the ultraviolet curable pressure-sensitive adhesive composition of the present invention, even a thin film of 1 to 20 μm has an excellent effect of adhesive strength to both high-polarity adherends and low-polarity adherends, and further retains the adhesive strength. The force and the adhesiveness to the curved surface are also good.

The pressure-sensitive adhesive sheet of the present invention can be used for various purposes regardless of the adherend from high polarity to low polarity such as plastics such as polyolefin, glass, cardboard, and metal.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the Examples. In the examples, "parts" means "parts by mass" and "%" means "% by mass".
The blending amount in the table is a part by mass, and is a non-volatile content conversion value except for the solvent. The blanks in the table indicate that they are not mixed.

The weight average molecular weight (Mw) and acid value of the copolymer were measured by the following methods.
<Measurement of weight average molecular weight (Mw)>
GPC was used for the measurement of the weight average molecular weight. GPC is a liquid chromatography in which a substance dissolved in a solvent (THF; tetrahydrofuran) is separated and quantified by the difference in its molecular size, and the weight average molecular weight is determined in terms of polystyrene.
Device name: LC-GPC system "Prominence" manufactured by Shimadzu Corporation
Column: 4 GMHXL manufactured by Tosoh Co., Ltd. and 1 HXL-H manufactured by Tosoh Co., Ltd. were connected in series.
Mobile phase solvent: Tetrahydrofuran Flow rate: 1.0 ml / min
Column temperature: 40 ° C

<Measurement of acid value>
Precisely weigh 1 g of the sample in a stoppered triangular flask, add 100 ml of a toluene / ethanol (volume ratio: toluene / ethanol = 2/1) mixture to dissolve, and then add to a 0.1 N-alcoholic potassium hydroxide solution. And titrated. The acid value (unit: mgKOH / g) was calculated by the following formula. The acid value was the value of the dried sample.
Acid value = {(5.61 × a × F) / S} / (nonvolatile content concentration / 100)
S: Sample collection amount (g)
a: Consumption of 0.1N-alcoholic potassium hydroxide solution (ml)
F: Factor of 0.1N-alcoholic potassium hydroxide solution

(Example 1)
20 parts of 2-ethylhexyl acrylate, n-butyl acrylate in a reaction vessel (hereinafter, simply referred to as "reaction vessel") equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen introduction tube under a nitrogen atmosphere. 75.9 parts, ω-carboxypolycaprolactone monoacrylate (manufactured by Toa Synthetic Co., Ltd., Aronix M-5300) 4 parts, 4-acryloyloxybenzophenone 0.1 parts, ethyl acetate 70 parts, 2,2'-azobisisobuty 0.015 parts of ronitrile was charged. Heating was carried out with stirring to confirm the start of the polymerization reaction, and the reaction was carried out at the reflux temperature for 2 hours. Then, 0.03 part of 2,2'-azobisisobutyronitrile was added to the reaction solution, and the reaction was continued for 6 hours. Then, the reaction vessel was cooled and ethyl acetate was added so that the non-volatile content of the reaction solution was 30% to obtain a copolymer (A-1) solution having a weight average molecular weight of 900,000.

The content of the monomer unit in this copolymer (A-1) is the same as the content of the monomer used. Therefore, the total of 2-ethylhexyl acrylate and n-butyl acrylate as the monomer unit (a1): 95.9% by mass, and ω-carboxypolycaprolactone monoacrylate as the monomer unit (a2): 4.0% by mass, As the monomer unit (a3), 4-acryloyloxybenzophenone: 0.1% by mass.

(Examples 2 to 19, Comparative Examples 1 to 4)
Copolymers (A-2) of Examples 1 to 19 and Comparative Examples 1 to 4 in the same manner as in Example 1 except that the composition and the blending amount (parts by mass) were changed as shown in Tables 1 and 2. -A-19, A'-1 to 4) solutions were obtained.
The content of the monomer unit in the copolymers (A-1 to A-19, A'-1 to 4) is the same as the content of the monomer used.

The abbreviations in Tables 1 and 2 are listed below.
2EHA: 2-Ethylhexyl acrylate BA: n-butyl acrylate M5300: ω-carboxypolycaprolactone monoacrylate (Aronix M-5300, manufactured by Toagosei Co., Ltd.), R ₁ of the general formula (11) is a hydrogen atom, m = 5, n = 2
βCEA: β-carboxyethyl acrylate (manufactured by Dycel Ornex, β-CEA), R ₁ of the general formula (11) is a hydrogen atom, m = 2, n = 1.
HOA-MS (N): 2-acryloyloxyethyl succinic acid (manufactured by Kyoeisha Chemical Co., Ltd., HOA-MS (N)), R ₂ of the general formula (21) is a hydrogen atom, R ₃ is an ethyl group, p = 2.
HOA-HH: 2-acryloyloxyethyl hexahydrophthalic acid (manufactured by Kyoeisha Chemical Co., Ltd., light acrylate HOA-HH), R ₂ of the general formula (21) is a hydrogen atom, R ₃ is a hexyl group, p = 2.
AA: Acrylic acid ABP: 4-Acryloyloxybenzophenone CHA: Cyclohexyl acrylate IBXA: Isobornyl acrylate ACMO: Acryloylmorpholin HEA: 2-Hydroxyethyl acrylate

(Example 20)
20 parts of 2-ethylhexyl acrylate, 75.8 parts of n-butyl acrylate, β-carboxyethyl acrylate (Dycel) in a reaction vessel equipped with a stirrer, thermometer, reflux cooling tube, dropping device, and nitrogen introduction tube under a nitrogen atmosphere. 4.1 parts of β-CEA) manufactured by Ornex, 70 parts of ethyl acetate, and 0.015 parts of 2,2'-azobisisobutyronitrile were charged. Heating was carried out with stirring to confirm the start of the polymerization reaction, and the reaction was carried out at the reflux temperature for 2 hours. Then, 0.03 part of 2,2'-azobisisobutyronitrile was added to the reaction solution, and the reaction was continued for 6 hours to obtain a precursor copolymer (A'-20) solution. After that, the air supply in the reaction vessel was switched from nitrogen to air, 0.1 part of glycidyl methacrylate, 30 parts of ethyl acetate, 0.08 part of trisdimethylaminomethylphenol, and 0.08 part of hydroquinone were added, and the inside was aired. After heating and stirring for 6 hours while replacing with, cool the reaction vessel and add ethyl acetate so that the non-volatile content of the reaction solution becomes 30% to obtain a copolymer (A-20) solution having a weight average molecular weight of 900,000. rice field.

The mass ratio of the monomer unit in this copolymer (A-20) is the total of 2-ethylhexyl acrylate and n-butyl acrylate as the monomer unit (a1): 95.8% by mass, and the monomer unit (1). β-carboxyethyl acrylate not used in the addition reaction of glycidyl methacrylate as a2): 4.0% by mass, as the monomer unit (a3) to β-carboxyethyl acrylate and the carboxyl group of β-carboxyethyl acrylate. The total amount of glycidyl methacrylate that has undergone the addition reaction; 0.2% by mass.

(Example 21)
20 parts of 2-ethylhexyl acrylate, 75.9 parts of n-butyl acrylate, β-carboxyethyl acrylate (Dycel) in a reaction vessel equipped with a stirrer, thermometer, reflux cooling tube, dropping device, and nitrogen introduction tube under a nitrogen atmosphere. 4 parts of β-CEA) manufactured by Ornex, 0.1 part of 2-hydroxyethyl acrylate, 70 parts of ethyl acetate, and 0.015 part of 2,2'-azobisisobutyronitrile were charged. Heating was carried out with stirring to confirm the start of the polymerization reaction, and the reaction was carried out at the reflux temperature for 2 hours. Then, 0.03 part of 2,2'-azobisisobutyronitrile was added to the reaction solution, and the reaction was continued for 6 hours to obtain a precursor (A'-21) solution. After that, the air supply in the reaction vessel was switched from nitrogen to air, and 0.1 part of 2-acryloyloxyethyl isocyanate, 30 parts of ethyl acetate, and 0.08 part of hydroquinone were charged, and 2270 cm ^-1 based on the isocyanate group by IR. The reaction was carried out until the disappearance of the peak of was confirmed. After confirming the disappearance of the peak, the mixture was cooled and ethyl acetate was added so that the non-volatile content of the reaction solution was 30% to obtain a copolymer (A-21) solution.

The mass ratio of the monomer unit in this copolymer (A-21) is the total of 2-ethylhexyl acrylate and n-butyl acrylate as the monomer unit (a1): 95.8% by mass, and the monomer unit (1). β-carboxyethyl acrylate as a2): 4.0% by mass, as the monomer unit (a3), hydroxyethyl acrylate and 2-acryloyloxyethyl isocyanate added and reacted to the hydroxyl group of hydroxyethyl acrylate: 0. 18% by mass, and as another monomer unit, hydroxyethyl acrylate not used in the addition reaction of 2-acryloyloxyethyl isocyanate: 0.02% by mass.

(Example 22)
A copolymer (A-3) solution having a non-volatile content of 30% was used as the pressure-sensitive adhesive composition.
The pressure-sensitive adhesive composition is coated on a removable sheet (made of polyethylene terephthalate) having a thickness of 38 μm with a comma coater so that the thickness after drying becomes 10 μm, and the pressure-sensitive adhesive composition is dried at 100 ° C. for 2 minutes to adhere. An agent layer was formed. Next, using an ultraviolet irradiation device, irradiation was performed so that the integrated light intensity was 50 mJ / m ² (high-pressure mercury lamp, irradiation intensity 120 W / cm ² ), and then the pressure-sensitive adhesive layer was coated with a 25 μm-thick substrate (polyethylene terephthalate). A pressure-sensitive adhesive sheet having a structure of "removable sheet / adhesive layer / PET sheet" was obtained by laminating the products (hereinafter referred to as PET sheets).

(Example 23)
For 100 parts of the copolymer (A-1), 10 parts of Pencel D-125 (manufactured by Arakawa Chemical Co., Ltd.), which is a rosin-based tackifier resin, and FTR6100 (synthetic hydrocarbon-based tackifier resin), which is a synthetic hydrocarbon-based tackifier resin. A pressure-sensitive adhesive composition was obtained by blending 10 parts (manufactured by Mitsui Chemicals, Inc.) and 1 part of Supercron 360T (manufactured by Nippon Paper Co., Ltd.), which is a polyolefin, and further adding ethyl acetate as a solvent to adjust the non-volatile content to 30%. ..

The obtained pressure-sensitive adhesive composition is coated on a removable sheet (made of polyethylene terephthalate) having a thickness of 38 μm with a comma coater so that the thickness after drying becomes 10 μm, and dried at 100 ° C. for 2 minutes. This formed a pressure-sensitive adhesive layer. Next, using an ultraviolet irradiation device, irradiation was performed so that the integrated light intensity was 50 mJ / m ² (high-pressure mercury lamp, irradiation intensity 120 W / cm ² ), and then the pressure-sensitive adhesive layer was coated with a 25 μm-thick substrate (polyethylene terephthalate). A pressure-sensitive adhesive sheet having a structure of "removable sheet / adhesive layer / PET sheet" was obtained by laminating the products (hereinafter referred to as PET sheets).

(Examples 24 to 32, 34 to 42, 46, 48 to 56, Comparative Examples 5 to 9)
Examples 24 to 32, 34 to 42, 46, 48 to 56 and Comparative Examples 5 to 9 are the same as in Example 23 except that the composition and the blending amount (parts by mass) are changed as shown in Tables 3 to 5. The pressure-sensitive adhesive composition and the pressure-sensitive adhesive sheet of the above were obtained.

(Example 33)
In the copolymer (A-10) solution containing 100 parts of the copolymer (A-10), 1.0 part (nonvolatile content equivalent) of trimethylolpropane adduct of tolylene diisocyanate as a curing agent, rosin-based tackifier resin Pencel D-125 (manufactured by Arakawa Chemical Co., Ltd.), 10 parts of FTR6100 (manufactured by Mitsui Chemicals Co., Ltd.), which is a synthetic hydrocarbon adhesive resin, and 1 part of Supercron 360T (manufactured by Nippon Paper Co., Ltd.), which is a polyolefin. Then, ethyl acetate was further added as a solvent to adjust the non-volatile content to 30%.

The obtained pressure-sensitive adhesive composition is coated on a removable sheet (made of polyethylene terephthalate) having a thickness of 38 μm with a comma coater so that the thickness after drying becomes 10 μm, and dried at 100 ° C. for 2 minutes. This formed a pressure-sensitive adhesive layer. Next, using an ultraviolet irradiation device, irradiation was performed so that the integrated light intensity was 50 mJ / m ² (high-pressure mercury lamp, irradiation intensity 120 W / cm ² ), and then the pressure-sensitive adhesive layer was coated with a 25 μm-thick substrate (polyethylene terephthalate). (Hereinafter referred to as PET sheet) was bonded and aged for one week at a temperature of 23 ° C. and a relative humidity of 50% to obtain an adhesive sheet having a structure of “release sheet / adhesive layer / PET sheet”.

(Example 44)
The pressure-sensitive adhesive composition and pressure-sensitive adhesive sheet of Example 44 were obtained in the same manner as in Example 33 except that the composition and the blending amount (parts by mass) were changed as shown in Table 4.

(Example 43)
0.1 part of Irgacure 184 (Omnirad 184 manufactured by BASF) as a photoinitiator in a copolymer (A-20) solution containing 100 parts of the copolymer (A-20), Pencel which is a rosin-based tackifier resin. 10 parts of D-125 (manufactured by Arakawa Chemical Co., Ltd.), 10 parts of FTR6100 (manufactured by Mitsui Chemicals Co., Ltd.), which is a synthetic hydrocarbon-based tackifier resin, 1 part of Supercron 360T (manufactured by Nippon Paper Co., Ltd.), which is a polyolefin, and further. Ethyl acetate was added as a solvent to adjust the non-volatile content to 30%.

The obtained pressure-sensitive adhesive composition is coated on a removable sheet (made of polyethylene terephthalate) having a thickness of 38 μm with a comma coater so that the thickness after drying becomes 10 μm, and dried at 100 ° C. for 2 minutes. This formed a pressure-sensitive adhesive layer. Next, using an ultraviolet irradiation device, irradiation was performed so that the integrated light intensity was 50 mJ / m ² (high-pressure mercury lamp, irradiation intensity 120 W / cm ² ), and then the pressure-sensitive adhesive layer was coated with a 25 μm-thick substrate (polyethylene terephthalate). A pressure-sensitive adhesive sheet having a structure of "removable sheet / adhesive layer / PET sheet" was obtained by laminating the products (hereinafter referred to as PET sheets).

(Examples 45 and 47)
The pressure-sensitive adhesive compositions and pressure-sensitive adhesive sheets of Examples 45 and 47 were obtained in the same manner as in Example 43 except that the composition and the blending amount (parts by mass) were changed as shown in Table 4.

<< Evaluation of adhesive sheet >>
The obtained adhesive sheet was evaluated by the following method. The results are shown in Tables 3-5.
(1) Adhesive strength The obtained adhesive sheet was prepared to have a width of 25 mm and a length of 100 mm. The peelable sheet was peeled off from the pressure-sensitive adhesive sheet under an atmosphere of 23 ° C. and a relative humidity of 50%, and the exposed pressure-sensitive adhesive layer was attached to a stainless steel (SUS) plate and pressure-bonded once with a 2 kg roll. After leaving it for 24 hours, the adhesive strength was measured in a 180 ° peel test in which the material was peeled off at a speed of 300 mm / min in the 180 degree direction using a tensile tester, and evaluation was performed based on the following evaluation criteria. (Compliant with JIS Z 0237: 2000)
A: "Adhesive strength is 12N or more, which is very good."
B: "Adhesive strength is 10N or more and less than 12N, which is good."
C: "Adhesive strength is 6N or more and less than 10N, and it is practical."
D: "Adhesive strength is less than 6N, so it is not practical."
The adhesive strength of the polypropylene (PP) plate was measured in the same manner as described above, and the evaluation was performed based on the following evaluation criteria.
A: "Adhesive strength is 12N or more, which is very good."
B: "Adhesive strength is 10N or more and less than 12N, which is good."
C: "Adhesive strength is 6N or more and less than 10N, and it is practical."
D: "Adhesive strength is less than 6N, so it is not practical."

(2) Holding power The obtained adhesive sheet was cut into a size of 25 mm in width and 100 mm in length and used as a sample. Next, in a 23 ° C.-50% RH atmosphere, the release sheet was peeled off from the sample in accordance with JIS Z 0237, and the exposed adhesive layer having a tip width of 25 mm and a length of 25 mm was attached to a polished stainless steel (SUS) plate. After wearing and crimping once with a 2 kg roll, a load of 1 kg was applied in an atmosphere of 70 ° C. and the mixture was held for 70,000 seconds. The evaluation indicates the number of seconds when the sample falls from the SUS plate. When the sample does not fall, it indicates the number of mm in which the adhesive tip of the adhesive layer and the SUS plate is displaced downward due to the load. The evaluation criteria are shown below.
A: "Sample displacement is less than 0.05 mm, which is very good."
B: "The deviation of the sample is 0.05 mm or more and less than 0.2 mm, which is good."
C: "The deviation of the sample is 0.2 mm or more and there is no drop, so it is practical."
D: "Sample dropped, not practical."

(3) Curved surface adhesiveness The obtained adhesive sheet was placed in a constant temperature and humidity chamber at 23 ° C.-50% RH, and a measurement sample having a length of 25 mm and a width of 15 mm was prepared. The peeling sheet was peeled off from the measurement sample, and the exposed pressure-sensitive adhesive layer was attached to a 10 mmφ cylindrical polypropylene (PP) resin in the circumferential direction and left to stand for 72 hours. After that, the sample was left to stand in an atmosphere of 80 ° C. for 24 hours, and then the peeled state of the end portion of the pasted measurement sample was visually observed and evaluated according to the following criteria.
A: "It is excellent because there is no peeling at the end."
B: "Peeling at the end is less than 3 mm in length, which is good."
C: "Peeling of the terminal part is 3 mm or more and less than 8 mm in length, and it is practical."
D: "The peeling of the end part is 8 mm or more in length, so it is not practical."

The abbreviations in Tables 3-5 are listed below.
<Curing agent>
TDI / TMP: Trimethylolpropane adduct of tolylene diisocyanate (nonvolatile content 37.5%)
<Adhesive-imparting resin>
D-125: Pencel D-125 (manufactured by Arakawa Chemical Co., Ltd., rosin-based adhesive resin)
FTR6100: FTR6100 (manufactured by Mitsui Chemicals, Inc., synthetic hydrocarbon-based tackifier resin (styrene-based tackifier resin))
T115: YS Polystar T115 (manufactured by Yasuhara Chemical Co., Ltd., terpene phenol-based adhesive-imparting resin)
PX1000: YS resin PX1000 (manufactured by Yasuhara Chemical Co., Ltd., terpene-based adhesive-imparting resin)
<Polyolefin>
360T: Supercron 360T (manufactured by Nippon Paper Industries, chlorinated polypropylene, chlorine content 31%)
930: Supercron 930 (manufactured by Nippon Paper Industries, chlorinated polypropylene, chlorine content 21%)
<Light initiator>
IRG184: Irgacure 184 (BASF, Omnirad 184, 1-hydroxycyclohexylphenyl ketone)

As shown in Tables 3 to 5, the pressure-sensitive adhesive sheet of the present invention has excellent adhesive strength to both a stainless steel plate which is a high-polarity adherend and a polypropylene plate which is a low-polarity adherend, and further has excellent holding power and curved surface adhesiveness. It was confirmed that it was excellent. On the other hand, in the comparative example adhesive sheet, one of the items is defective, which is practically problematic and impractical.

Claims (7)

Contains the copolymer (A) having an ultraviolet reactive group,
The copolymer (A) has a weight average molecular weight of 400,000 to 1,500,000 and has a weight average molecular weight of 400,000 to 1,500,000.
A copolymer having a monomer unit (a1) having an alkyl group, a monomer unit (a2) having a carboxyl group, and a monomer unit (a3) having an ultraviolet reactive group.
The content of the monomer unit (a3) is 0.01 to 5% by mass in a total of 100% by mass of all the monomer units.
The monomer unit (a2) having a carboxyl group includes the monomer unit (a2-1) represented by the following general formula (1) and the monomer unit (a2) represented by the following general formula (2). An ultraviolet curable pressure-sensitive adhesive composition comprising at least one of -2).

(In the general formula (1), R ₁₁ is a hydrogen atom or a methyl group, m is an integer of 2 to 10, and n is an integer of 1 to 5.)

(In the general formula (2), R ₂₁ is a hydrogen atom or a methyl group, R ₃ is a divalent hydrocarbon group, and p is an integer of 1 to 5.) The ultraviolet curable pressure-sensitive adhesive composition according to claim 1, wherein the monomer unit (a3) having an ultraviolet reactive group has a benzophenone group. The ultraviolet curable pressure-sensitive adhesive composition according to claim 1 or 2, further comprising an organic solvent. In addition, it contains an adhesive resin,
The one according to any one of claims 1 to 3, wherein the tackifier resin contains at least one selected from the group consisting of a rosin-based tackifier resin, a synthetic hydrocarbon-based tackifier resin, and a terpenephenol-based tackifier resin. UV curable adhesive composition. The ultraviolet curable pressure-sensitive adhesive composition according to any one of claims 1 to 4, further comprising a polyolefin. A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer obtained by UV-curing a layer formed from the pressure-sensitive adhesive composition according to any one of claims 1 to 5. The pressure-sensitive adhesive sheet according to claim 6, wherein the pressure-sensitive adhesive layer cured by ultraviolet rays has a thickness of 1 to 20 μm.