JP2023057915A - Adhesive composition and adhesive sheet - Google Patents

Abstract

[Problem] To provide a pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet capable of forming a pressure-sensitive adhesive sheet having high adhesive strength and excellent outgas resistance. The pressure-sensitive adhesive composition contains a (meth)acrylic polymer and a silane coupling agent, and the (meth)acrylic polymer comprises (meth)acrylic acid ester monomer units and hydroxyl group-containing (meth)acrylic monomer units. and a metal salt of unsaturated group-containing monomer units, and the (meth)acrylic polymer contains 10% by mass or more of (meth)acrylic monomer units having a hydroxyl group. Another adhesive composition contains a (meth)acrylic polymer, a silane coupling agent, and a metal salt of an unsaturated group-containing monomer, and the (meth)acrylic polymer contains (meth)acrylic acid ester monomer units and hydroxyl groups. The (meth)acrylic polymer contains 10% by mass or more of (meth)acrylic monomer units having a hydroxyl group. [Selection figure] None

Description

TECHNICAL FIELD The present invention relates to an adhesive composition and an adhesive sheet.

2. Description of the Related Art Conventionally, display devices such as liquid crystal displays (LCDs) and input devices such as touch panels used in combination with display devices have been widely used. In the manufacture of these display devices and input devices, transparent adhesive sheets are used for bonding optical members, and transparent adhesive sheets are also used for bonding display devices and input devices. .

In order to improve the performance of such pressure-sensitive adhesive sheets, pressure-sensitive adhesive compositions that serve as raw materials for producing pressure-sensitive adhesive sheets have also been extensively studied. For example, various polymerization methods are used to obtain various pressure-sensitive adhesive compositions. A method is also proposed. For example, Patent Document 1 discloses a pressure-sensitive adhesive containing a polymer component obtained by reacting an acrylic polymer obtained by polymerizing a specific acrylic monomer with an epoxy compound in the presence of an alkali metal. It is disclosed that this allows the adhesiveness to be adjusted.

JP-A-2000-44912

In recent years, in addition to the strong demand for increasing the adhesiveness of adhesive sheets in various applications, it is also desired to improve the outgassing resistance against heating when the adhesive sheet is attached to an adherend. It is rare. In particular, when the adherend is bonded with the adhesive sheet, there is a problem that gas generated from the adherend (so-called outgas) may cause air bubbles, floating, peeling, etc. at the adhesive interface. However, the utility value of a pressure-sensitive adhesive sheet with improved outgas resistance is extremely high.

The present invention has been made in view of the above, and provides a pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive sheet having high adhesive strength and excellent outgassing resistance, and a pressure-sensitive adhesive composition formed from the pressure-sensitive adhesive composition. An object of the present invention is to provide a pressure-sensitive adhesive sheet.

As a result of intensive studies aimed at achieving the above object, the present inventors have found that the above object can be achieved by including a metal salt of a specific unsaturated group-containing monomer, and have completed the present invention. .

That is, the present invention includes, for example, the subject matter described in the following sections.
Item 1
(Meth) acrylic polymer and a silane coupling agent,
The (meth)acrylic polymer includes (meth)acrylic acid ester monomer units, (meth)acrylic monomer units having hydroxyl groups, and metal salts of unsaturated group-containing monomer units,
The pressure-sensitive adhesive composition, wherein the (meth)acrylic polymer contains 10% by mass or more of (meth)acrylic monomer units having a hydroxyl group.
Item 2
A (meth) acrylic polymer, a silane coupling agent, and a metal salt of an unsaturated group-containing monomer,
The (meth)acrylic polymer includes (meth)acrylic acid ester monomer units and hydroxyl group-containing (meth)acrylic monomer units,
The pressure-sensitive adhesive composition, wherein the (meth)acrylic polymer contains 10% by mass or more of (meth)acrylic monomer units having a hydroxyl group.
Item 3
Item 3. The adhesive composition according to Item 1 or 2, wherein the metal salt of the unsaturated group-containing monomer has one or more radically polymerizable unsaturated bonds.
Item 4
Item 4. The pressure-sensitive adhesive composition according to any one of items 1 to 3, further comprising a polyfunctional monomer.
Item 5
Item 5. The pressure-sensitive adhesive composition according to any one of Items 1 to 4, further comprising a cross-linking agent.
Item 6
Item 6. The pressure-sensitive adhesive composition according to any one of Items 1 to 5, further comprising a photopolymerization initiator.
Item 7
A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer containing a cured product of the pressure-sensitive adhesive composition according to any one of Items 1 to 6.

ADVANTAGE OF THE INVENTION In addition to having high adhesive strength, the adhesive composition of this invention can form the adhesive sheet which is excellent also in outgassing resistance.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail. In this specification, the expressions "contain" and "include" include the concepts of "contain", "include", "substantially consist of" and "consist only of".

In the numerical ranges described stepwise in this specification, the upper limit value or lower limit value of the numerical range in one step can be arbitrarily combined with the upper limit value or lower limit of the numerical range in another step. In the numerical ranges described herein, the upper and lower limits of the numerical ranges may be replaced with values shown in Examples or values that can be uniquely derived from Examples. Further, in this specification, a numerical value connected with "-" means a numerical range including numerical values before and after "-" as lower and upper limits.

1. Adhesive composition One embodiment of the adhesive composition according to the present invention includes the following adhesive composition 1, and other embodiments of the adhesive composition according to the present invention include the following The pressure-sensitive adhesive composition 2 can be mentioned. That is, the pressure-sensitive adhesive composition according to the present invention includes pressure-sensitive adhesive composition 1 and pressure-sensitive adhesive composition 2. In this specification, the expression "the adhesive composition of the present invention" includes the adhesive composition 1 and the adhesive composition 2.

Adhesive composition 1;
The adhesive composition 1 contains a (meth) acrylic polymer and a silane coupling agent,
The (meth)acrylic polymer includes (meth)acrylic acid ester monomer units, (meth)acrylic monomer units having hydroxyl groups, and metal salts of unsaturated group-containing monomer units,
The (meth)acrylic polymer contains 10% by mass or more of (meth)acrylic monomer units having a hydroxyl group.

Adhesive composition 2;
The pressure-sensitive adhesive composition 2 contains a (meth)acrylic polymer, a silane coupling agent, and a metal salt of an unsaturated group-containing monomer, and the (meth)acrylic polymer comprises (meth)acrylic acid ester monomer units, and (meth)acrylic monomer units having a hydroxyl group, and the (meth)acrylic polymer contains 10% by mass or more of the (meth)acrylic monomer units having a hydroxyl group.

A pressure-sensitive adhesive sheet can be formed by using the pressure-sensitive adhesive composition according to the present invention. Specifically, a cured product formed by curing the pressure-sensitive adhesive composition of the present invention can be used as a component of the pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet. A pressure-sensitive adhesive sheet having such a pressure-sensitive adhesive layer is formed from the pressure-sensitive adhesive composition according to the present invention, and thus has high adhesive strength and excellent outgas resistance. In particular, the pressure-sensitive adhesive sheet obtained from the pressure-sensitive adhesive composition according to the present invention can have high adhesion to glass.

In this specification, "(meth)acryl" means "acryl" or "methacryl", and "(meth)acrylate" means "acrylate" or "methacrylate".

First, the (meth)acrylic polymer contained in the pressure-sensitive adhesive composition according to the present invention will be explained. Here, the (meth)acrylic polymer contained in the adhesive composition 1 and the adhesive composition 2 will be described, and the (meth)acrylic polymer contained in the adhesive composition 1 is "(meth)acrylic polymer 1", the adhesive The (meth)acrylic polymer contained in the agent composition 2 is referred to as "(meth)acrylic polymer 2". In the present specification, the expression "(meth)acrylic polymer" includes (meth)acrylic polymer 1 and (meth)acrylic polymer 2.

((Meth) acrylic polymer 1)
The (meth)acrylic polymer 1 contains a (meth)acrylic acid ester monomer unit, a (meth)acrylic monomer unit having a hydroxyl group, and a metal salt of an unsaturated group-containing monomer unit. As a result, the pressure-sensitive adhesive sheet to be obtained has high adhesive strength and is excellent in outgassing resistance.

A (meth)acrylic acid ester monomer unit means a structural unit formed by polymerizing a (meth)acrylic acid ester monomer. However, the (meth)acrylic acid ester monomer unit excludes the metal salt of the (meth)acrylic monomer unit having a hydroxyl group and the unsaturated group-containing monomer unit described later.

(Meth)acrylic acid ester monomers include, for example, (meth)acrylates having linear, branched or cyclic alkyl groups, or (meth)acrylates having an aromatic ring. When the (meth)acrylate has a linear, branched or cyclic alkyl group, the number of carbon atoms can be, for example, 1-20, preferably 1-10. When the (meth)acrylate has an aromatic ring, its carbon number can be, for example, 5-20, preferably 6-10. Specific examples of (meth)acrylate monomers include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, isopropyl (meth) acrylate, isooctyl (meth) ) acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate and the like.

Among these, the (meth)acrylic acid ester monomers include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate, isopropyl (meth)acrylate, isooctyl (meth) It is preferably one or more selected from the group consisting of acrylate, 2-ethylhexyl(meth)acrylate and cyclohexyl(meth)acrylate. In this case, it is easy to obtain a PSA sheet with high adhesive strength and excellent outgas resistance.

The (meth)acrylic acid ester monomer unit contained in the (meth)acrylic polymer 1 may be of one type alone, or may be of two or more types. (Meth)acrylic acid ester monomer units contained in the (meth)acrylic polymer include (meth)acrylates having a linear alkyl group, (meth)acrylates having a branched chain, and (meth)acrylates having a cyclic alkyl group. Two or more of these may be included.

A (meth)acrylic monomer unit having a hydroxyl group means a structural unit formed by polymerizing a hydroxyl group-containing (meth)acrylic monomer. Examples of such hydroxyl group-containing (meth)acrylic monomers include a wide range of (meth)acrylic monomers having one or more hydroxyl groups in the molecule. ) acrylate, 6-hydroxyhexyl (meth)acrylate, 5-hydroxypentyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2-hydroxy 3-phenoxypropyl (meth)acrylate, 2,2-dimethyl 2-hydroxy Hydroxyalkyl (meth)acrylates such as ethyl (meth)acrylate, 3-chloro 2-hydroxypropyl (meth)acrylate, 2-hydroxy 3-phenoxypropyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate; N-hydroxy hydroxyalkyl (meth)acrylamide such as propyl (meth)acrylamide;

Among these, the hydroxyl group-containing (meth)acrylic monomer is one or more selected from the group consisting of 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate and 6-hydroxyhexyl (meth)acrylate. is preferred. In this case, it is easy to obtain a PSA sheet with high adhesive strength and excellent outgas resistance.

The (meth)acrylic monomer unit having a hydroxyl group contained in the (meth)acrylic polymer 1 may be of one type alone, or may be of two or more types.

A metal salt of an unsaturated group-containing monomer unit means a structural unit formed by polymerizing a metal salt of an unsaturated group-containing monomer (the unsaturated group can become a saturated group by polymerization). The metal salt of the unsaturated group-containing monomer unit may be a structural unit formed by polymerization of the unsaturated group-containing monomer, which is converted into a metal salt by neutralization treatment.

In the metal salt of the unsaturated group-containing monomer, the unsaturated group-containing monomer specifically includes a monomer having a polymerizable unsaturated group, particularly a monomer having a radically polymerizable unsaturated group. can be mentioned. A vinyl group, an allyl group, a (meth)acryloyl group, etc. are illustrated as a radically polymerizable unsaturated group, Among them, a (meth)acryloyl group is preferable. Accordingly, examples of metal salts of unsaturated group-containing monomers include the various metal salts of (meth)acrylic acid.

In the metal salt of the unsaturated group-containing monomer, the type of metal is not particularly limited, and examples thereof include alkali metals, alkaline earth metals, and various transition metals. Alkali metals are not particularly limited, and examples thereof include lithium, potassium, and sodium. Alkaline earth metals are not particularly limited, and examples thereof include magnesium and calcium. The transition metal is not particularly limited, and examples thereof include zinc, copper, iron, manganese, nickel, cobalt and the like.

Examples of the metal in the metal salt of the unsaturated group-containing monomer include various metals capable of forming monovalent or divalent or higher valence ions (eg, divalent, trivalent, or tetravalent) ions. When the metal in the metal salt of the unsaturated group-containing monomer is a metal that can form divalent or higher ions, the unsaturated group-containing monomer can have two or more unsaturated groups. And it is easy to obtain a pressure-sensitive adhesive sheet with improved outgas resistance.

The metal salt of the unsaturated group-containing monomer preferably has two or more radically polymerizable unsaturated bonds (that is, the metal salt of the unsaturated group-containing monomer unit has at least one radically polymerizable unsaturated bond. It is preferable to have 2 or more). This is because, in this case, the cohesive force of the (meth)acrylic polymer 1 in the pressure-sensitive adhesive sheet is increased, and the outgas resistance is particularly likely to be improved. In particular, the metal salt of the unsaturated group-containing monomer preferably has two or more (meth)acryloyl groups. The number of radically polymerizable unsaturated bonds in the metal salt of the unsaturated group-containing monomer can be, for example, 5 or less.

Examples of the metal salt of the unsaturated group-containing monomer include sodium (meth)acrylate, magnesium (meth)acrylate, zinc (meth)acrylate and the like. ) Magnesium acrylate and zinc (meth)acrylate are preferred.

(Meth)acrylic polymer 1 has a structural unit (another monomer unit) other than a metal salt of a (meth)acrylic acid ester monomer unit, a (meth)acrylic monomer unit having a hydroxyl group, and an unsaturated group-containing monomer unit. can also

Examples of monomers for forming other monomer units include (meth)acrylic monomers having a carboxy group, an amino group, an amide group, an epoxy group, a thiol group, an isocyanate group, and the like. Examples of such monomers include (meth)acrylic acid. The other monomer units contained in the (meth)acrylic polymer 1 may be of one type alone, or may be of two or more types.

The (meth)acrylic polymer 1 contains 10% by mass or more of (meth)acrylic monomer units having a hydroxyl group. This makes it easier to obtain a pressure-sensitive adhesive sheet with high pressure-sensitive adhesive strength. The (meth)acrylic polymer 1 preferably contains 15% by mass or more of a (meth)acrylic monomer unit having a hydroxyl group, more preferably 20% by mass or more, further preferably 25% by mass or more, and 30% by mass. It is particularly preferable to include the above. (Meth)acrylic polymer 1 preferably contains 60% by mass or less of a (meth)acrylic monomer unit having a hydroxyl group, more preferably 55% by mass or less, even more preferably 50% by mass or less, and 45% by mass. It is particularly preferred to include:

The (meth)acrylic polymer 1 preferably contains 30% by mass or more of the (meth)acrylic acid ester monomer unit. This makes it easier to obtain a PSA sheet with higher adhesive strength and more excellent outgas resistance. The (meth)acrylic polymer 1 preferably contains 40% by mass or more of the (meth)acrylic acid ester monomer unit, and more preferably 50% by mass or more. The (meth)acrylic polymer 1 more preferably contains 95% by mass or less of the (meth)acrylic acid ester monomer units, further preferably 85% by mass or less, and particularly preferably 80% by mass or less.

In the (meth)acrylic polymer 1, the content ratio of the metal salt of the unsaturated group-containing monomer unit is not particularly limited. For example, from the viewpoint that a pressure-sensitive adhesive sheet having higher adhesive strength and better outgassing resistance can be easily obtained, the content of the metal salt in the unsaturated group-containing monomer unit is the (meth)acrylic acid ester monomer unit and the It is preferably 0.1 parts by mass or more, more preferably 0.15 parts by mass or more, and 0.2 parts by mass or more with respect to 100 parts by mass of the total amount of (meth)acrylic monomer units having a hydroxyl group. It is even more preferable to have In addition, from the viewpoint that it is easy to obtain a pressure-sensitive adhesive sheet having higher adhesive strength and better outgas resistance, the content of the metal salt in the unsaturated group-containing monomer unit is the same as the (meth)acrylate monomer unit and It is preferably 10 parts by mass or less, more preferably 7 parts by mass or less, and even more preferably 5 parts by mass or less with respect to 100 parts by mass of the total amount of (meth)acrylic monomer units having a hydroxyl group. It is particularly preferable that it is 3 parts by mass or less.

((Meth) acrylic polymer 2)
The (meth)acrylic polymer 2 contains a (meth)acrylic acid ester monomer unit and a (meth)acrylic monomer unit having a hydroxyl group. As a result, the pressure-sensitive adhesive sheet to be obtained has high adhesive strength and is excellent in outgassing resistance.

A (meth)acrylic acid ester monomer unit means a structural unit formed by polymerizing a (meth)acrylic acid ester monomer. However, the (meth)acrylic acid ester monomer unit excludes the metal salt of the (meth)acrylic monomer unit having a hydroxyl group and the unsaturated group-containing monomer unit described later.

(Meth)acrylic acid ester monomers include, for example, (meth)acrylates having linear, branched or cyclic alkyl groups, or (meth)acrylates having an aromatic ring. When the (meth)acrylate has a linear, branched or cyclic alkyl group, the number of carbon atoms can be, for example, 1-20, preferably 1-10. When the (meth)acrylate has an aromatic ring, its carbon number can be, for example, 5-20, preferably 6-10. Specific examples of (meth)acrylate monomers include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, isopropyl (meth) acrylate, isooctyl (meth) ) acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate and the like.

Among these, the (meth)acrylic acid ester monomers include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate, isopropyl (meth)acrylate, isooctyl (meth) It is preferably one or more selected from the group consisting of acrylate, 2-ethylhexyl(meth)acrylate and cyclohexyl(meth)acrylate. In this case, it is easy to obtain a PSA sheet with high adhesive strength and excellent outgas resistance.

The (meth)acrylic acid ester monomer unit contained in the (meth)acrylic polymer 2 may be of one type alone, or may be of two or more types. (Meth)acrylic acid ester monomer units contained in the (meth)acrylic polymer include (meth)acrylates having a linear alkyl group, (meth)acrylates having a branched chain, and (meth)acrylates having a cyclic alkyl group. Two or more of these may be included.

A (meth)acrylic monomer unit having a hydroxyl group means a structural unit formed by polymerizing a hydroxyl group-containing (meth)acrylic monomer. Examples of such hydroxyl group-containing (meth)acrylic monomers include a wide range of (meth)acrylic monomers having one or more hydroxyl groups in the molecule. ) acrylate, 6-hydroxyhexyl (meth)acrylate, 5-hydroxypentyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2-hydroxy 3-phenoxypropyl (meth)acrylate, 2,2-dimethyl 2-hydroxy Hydroxyalkyl (meth)acrylates such as ethyl (meth)acrylate, 3-chloro 2-hydroxypropyl (meth)acrylate, 2-hydroxy 3-phenoxypropyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate; N-hydroxy hydroxyalkyl (meth)acrylamide such as propyl (meth)acrylamide;

Among these, the hydroxyl group-containing (meth)acrylic monomer is one or more selected from the group consisting of 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate and 6-hydroxyhexyl (meth)acrylate. is preferred. In this case, it is easy to obtain a PSA sheet with high adhesive strength and excellent outgas resistance.

The (meth)acrylic monomer unit having a hydroxyl group contained in the (meth)acrylic polymer 2 may be of one type alone, or may be of two or more types.

The (meth)acrylic polymer 2 can also have structural units (other monomer units) other than the (meth)acrylic acid ester monomer unit and the (meth)acrylic monomer unit having a hydroxyl group. In addition, the (meth)acrylic polymer 2 can also contain a metal salt of the unsaturated group-containing monomer unit, similarly to the (meth)acrylic polymer 1 .

Examples of monomers for forming other monomer units include (meth)acrylic monomers having a carboxy group, an amino group, an amide group, an epoxy group, a thiol group, an isocyanate group, and the like. Examples of such monomers include (meth)acrylic acid. Other monomer units contained in the (meth)acrylic polymer 2 may be of one type alone, or may be of two or more types.

The (meth)acrylic polymer 2 contains 10% by mass or more of (meth)acrylic monomer units having a hydroxyl group. This makes it easier to obtain a pressure-sensitive adhesive sheet with high pressure-sensitive adhesive strength. The (meth)acrylic polymer 2 preferably contains 15% by mass or more of (meth)acrylic monomer units having a hydroxyl group, more preferably 20% by mass or more, further preferably 25% by mass or more, and 30% by mass. It is particularly preferable to include the above. The (meth)acrylic polymer 2 preferably contains 60% by mass or less of (meth)acrylic monomer units having a hydroxyl group, more preferably 55% by mass or less, even more preferably 50% by mass or less, and 45% by mass. It is particularly preferred to include:

The (meth)acrylic polymer 2 preferably contains 30% by mass or more of the (meth)acrylic acid ester monomer unit. This makes it easier to obtain a PSA sheet with higher adhesive strength and more excellent outgas resistance. The (meth)acrylic polymer 2 preferably contains 40% by mass or more of the (meth)acrylic acid ester monomer unit, and more preferably 50% by mass or more. The (meth)acrylic polymer 2 preferably contains 95% by mass or less of the (meth)acrylic acid ester monomer unit, further preferably 85% by mass or less, and particularly preferably 80% by mass or less.

(Common Matters for (Meth)Acrylic Polymers)
Common items of the (meth)acrylic polymers 1 and 2 are described below.

A (meth)acrylic polymer can be produced, for example, by polymerizing a monomer mixture for forming each monomer unit by a known polymerization method. As this polymerization method, for example, solution polymerization, bulk polymerization, suspension polymerization, emulsion polymerization, or the like can be employed. The ratio of each monomer unit in the (meth)acrylic polymer corresponds to the usage ratio of each monomer used during polymerization.

A solvent can be used as necessary in polymerizing the (meth)acrylic polymer. The type of solvent is not particularly limited, and for example, a wide range of known organic solvents used in polymerization can be used. Examples thereof include ester compounds such as ethyl acetate and butyl acetate; ketones such as acetone and methyl ethyl ketone; hydrocarbons such as hexane; and aromatic compounds such as toluene, xylene and benzene. The amount of the solvent used in the polymerization reaction is not particularly limited.

A polymerization initiator can be used in polymerizing the (meth)acrylic polymer, and for example, a wide range of known polymerization initiators used in general polymerization can be used. Examples of polymerization initiators include azobisisobutyronitrile, 2,2′-azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride, 1,1′-azobis(cyclohexanecarbonitrile), di-tert-butyl peroxide, tert-butyl hydroperoxide, benzoyl peroxide, ammonium persulfate, photopolymerization initiators (Irgacure or Omnilad (registered trademark) series, etc.) and the like. The amount of the polymerization initiator to be used is not particularly limited, and can be appropriately adjusted according to, for example, the target molecular weight.

In polymerizing the (meth)acrylic polymer, for example, known chain transfer agents, polymerization accelerators and the like can be used.

The polymerization time and polymerization temperature are also not limited, and can be appropriately set according to the type and amount of monomer used, polymerization reactivity, and the like. For example, the polymerization reaction can be carried out at 20 to 100° C. for 1 to 24 hours. Polymerization can be appropriately carried out under an inert gas atmosphere such as nitrogen.

The weight-average molecular weight of the (meth)acrylic polymer is not particularly limited. For example, from the viewpoint that the pressure-sensitive adhesive sheet does not easily deteriorate in adhesive force, it can be 100,000 to 2,000,000, and 300,000 to 1,000,000. is more preferred.

In addition, the weight average molecular weight as used in the field of this invention is the polystyrene conversion weight average molecular weight measured by the gel permeation chromatography (GPC) method. The GPC apparatus used in the GPC method is not particularly limited, and commercially available GPC measuring instruments such as LC-2000Plus series manufactured by JASCO Corporation, and RI-2031Plus and UV-2075Plus as detectors can be used. In this case, for example, a GPC column formed by connecting four columns of "Shodex KF801", "Shodex KF803L", "Shodex KF800L" and "Shodex KF800D" manufactured by Showa Denko KK is used. The column temperature can be 40°C. Tetrahydrofuran is used as the eluent, and the measurement is performed at a flow rate of 1.0 ml/min. Normally, a standard polystyrene is used to prepare a calibration curve, and the weight average molecular weight (Mw) can be obtained by polystyrene conversion.

The (meth)acrylic polymer may be a random copolymer, or the (meth)acrylic polymer may have other structures such as block polymers.

Components other than the (meth)acrylic polymer contained in the pressure-sensitive adhesive composition of the present invention are described below.

(Metal salt of unsaturated group-containing monomer)
The pressure-sensitive adhesive composition 2 of the present invention contains a metal salt of an unsaturated group-containing monomer as an essential component. In the metal salt of the unsaturated group-containing monomer, the unsaturated group-containing monomer specifically includes a monomer having a polymerizable unsaturated group, particularly a monomer having a radically polymerizable unsaturated group. can be mentioned. A vinyl group, an allyl group, a (meth)acryloyl group, etc. are illustrated as a radically polymerizable unsaturated group, Among them, a (meth)acryloyl group is preferable. Accordingly, examples of metal salts of unsaturated group-containing monomers include the various metal salts of (meth)acrylic acid.

In the metal salt of the unsaturated group-containing monomer, the type of metal is not particularly limited, and examples thereof include alkali metals, alkaline earth metals, and various transition metals. Alkali metals are not particularly limited, and examples thereof include lithium, potassium, and sodium. Alkaline earth metals are not particularly limited, and examples thereof include magnesium and calcium. The transition metal is not particularly limited, and examples thereof include zinc, copper, iron, manganese, nickel, cobalt and the like.

Examples of the metal in the metal salt of the unsaturated group-containing monomer include various metals capable of forming monovalent or divalent or higher valence ions (eg, divalent, trivalent, or tetravalent) ions. When the metal in the metal salt of the unsaturated group-containing monomer is a metal that can form divalent or higher ions, the unsaturated group-containing monomer can have two or more unsaturated groups. And it is easy to obtain a pressure-sensitive adhesive sheet with improved outgas resistance.

The metal salt of the unsaturated group-containing monomer preferably has two or more radically polymerizable unsaturated bonds. In this case, the cohesive force of the (meth)acrylic polymer in the pressure-sensitive adhesive sheet is increased, so that the outgas resistance is particularly likely to be improved. In particular, the metal salt of the unsaturated group-containing monomer preferably has two or more (meth)acryloyl groups. The number of radically polymerizable unsaturated bonds in the metal salt of the unsaturated group-containing monomer can be, for example, 5 or less.

Examples of the metal salt of the unsaturated group-containing monomer include sodium (meth)acrylate, magnesium (meth)acrylate, zinc (meth)acrylate and the like. ) Magnesium acrylate and zinc (meth)acrylate are preferred.

In the adhesive composition 2 of the present invention, the content ratio of the metal salt of the unsaturated group-containing monomer is not particularly limited. For example, the content of the metal salt of the unsaturated group-containing monomer is 100 parts by mass of the (meth)acrylic polymer 2 in that a pressure-sensitive adhesive sheet having higher adhesive strength and better outgas resistance can be easily obtained. is preferably 0.1 parts by mass or more, more preferably 0.15 parts by mass or more, and even more preferably 0.2 parts by mass or more. In addition, the content of the metal salt of the unsaturated group-containing monomer is 100 parts by mass of the (meth)acrylic polymer 2 from the viewpoint that it is easy to obtain a pressure-sensitive adhesive sheet having higher adhesive strength and better outgas resistance. is preferably 10 parts by mass or less, more preferably 7 parts by mass or less, even more preferably 5 parts by mass or less, and particularly preferably 3 parts by mass or less.

However, the pressure-sensitive adhesive composition 2 of the present invention may contain a polymerizable monomer M in addition to the (meth)acrylic polymer 2 as described later. Only in this case, in the pressure-sensitive adhesive composition 2, the content of the metal salt of the unsaturated group-containing monomer is based on the total mass of 100 parts by mass of the (meth)acrylic polymer 2 and the polymerizable monomer M , preferably 0.1 parts by mass or more, more preferably 0.15 parts by mass or more, further preferably 0.2 parts by mass or more, and 10 parts by mass or less It is preferably 7 parts by mass or less, more preferably 5 parts by mass or less, and particularly preferably 3 parts by mass or less.

In the pressure-sensitive adhesive composition 2 of the present invention, the metal salt of the unsaturated group-containing monomer may be used singly or in combination of two or more. The pressure-sensitive adhesive composition 1 of the present invention may also contain a metal salt of an unsaturated group-containing monomer, although this is not essential.

(Silane coupling agent)
The pressure-sensitive adhesive compositions 1 and 2 of the present invention contain a silane coupling agent as an essential component. By including a silane coupling agent in the pressure-sensitive adhesive composition of the present invention, the pressure-sensitive adhesive strength to an adherend (particularly glass) can be enhanced. In particular, as in the adhesive composition 1 of the present invention, the (meth)acrylic polymer 1 containing a metal salt of unsaturated group-containing monomer units and a silane coupling agent are combined to form an adherend (especially glass ) is remarkably increased, and the outgassing resistance is also improved. Further, like the adhesive composition 2 of the present invention, the (meth)acrylic polymer 2, the metal salt of the unsaturated group-containing monomer, and the silane coupling agent are combined to form an adherend (particularly glass). The adhesive strength to the is remarkably increased, and the outgassing resistance is also more excellent.

The type of silane coupling agent is not particularly limited, and for example, a wide range of known compounds can be used. Silane coupling agents include, for example, γ-acryloxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyldialkoxysilane, γ- Aminopropyltriethoxysilane, γ-Aminopropyltrimethoxysilane, γ-Glycidoxypropyltriacoxysilane, γ-Methacryloxypropyltrialkoxysilane, γ-Chloropropyltrialkoxysilane, γ-Methacryloxypropyldialkoxysilane , γ-mercaptopropyltrialkoxysilane, vinyltrialkoxysilane, and the like. The silane coupling agent may also be an oligomer of various alkoxysiloxanes. All of these silane coupling agents are commercially available.

In the adhesive composition 1 of the present invention, the content of the silane coupling agent can be 0.1 to 5 parts by mass with respect to 100 parts by mass of the (meth)acrylic polymer 1. Silane coupling agents may be used alone or in combination of two or more. In the adhesive composition 2 of the present invention, the content of the silane coupling agent is 100 parts by mass of the (meth)acrylic polymer 2 (however, when the polymerizable monomer M described later is included, the (meth)acrylic It can be 0.1 to 5 parts by mass with respect to 100 parts by mass of the total mass of the polymer 2 and the polymerizable monomer M). Silane coupling agents may be used alone or in combination of two or more.

(Other components in the adhesive composition)
The pressure-sensitive adhesive composition of the present invention can contain other components in addition to the silane coupling agent. For example, the adhesive composition of the present invention can further contain a cross-linking agent. In this case, the (meth)acrylic polymer can form a crosslinked structure, thereby further improving the adhesive strength of the obtained adhesive sheet. In this specification, the cross-linking agent does not contain the metal salt of the unsaturated group-containing monomer.

Cross-linking agents can include, for example, a wide range of components that can promote cross-linking of (meth)acrylic polymers. In particular, the cross-linking agent can broadly include components that can react with hydroxyl groups in the (meth)acrylic polymer.

Examples of such cross-linking agents include widely known cross-linking agents such as isocyanate cross-linking agents and epoxy cross-linking agents.

The type of isocyanate cross-linking agent is not particularly limited, and a wide range of known compounds can be used. Examples of isocyanate cross-linking agents include polyisocyanates such as tolylene diisocyanate, chlorophenylene diisocyanate, diphenylmethane diisocyanate, butylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, hydrogenated diphenylmethane diisocyanate, and xylylene diisocyanate; cyclopentylene diisocyanate, cyclohexylene diisocyanate; and aromatic isocyanates such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, and 4,4′-diphenylmethane diisocyanate. An isocyanate crosslinking agent can be used individually or in mixture of 2 or more different types. Moreover, it is more preferable to use trifunctional derivatives such as adducts, nurates, and burettes obtained from the above diisocyanates as isocyanate cross-linking agents.

The type of epoxy cross-linking agent is not particularly limited, and a wide range of known compounds can be used. Examples of epoxy crosslinking agents include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, glycerin diglycidyl ether, neopentyl glycol diglycidyl ether, and 1,6-hexanediol. Diglycidyl ether, N,N,N',N'-tetraglycidyl-m-xylenediamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexanone, trimethylolpropane polyglycidyl ether, diglycerol polyglycidyl Ether, polyglycerol polyglycidyl ether, sorbitol polyglycidyl ether and the like.

When the pressure-sensitive adhesive composition 1 of the present invention contains a cross-linking agent, the content ratio is not particularly limited, for example, 0.01 to 5 parts by mass is used with respect to 100 parts by mass of the (meth)acrylic polymer 1. can be done. In this case, the adhesive sheet tends to have high adhesive strength. The content of the cross-linking agent is preferably 0.05 to 1 part by mass with respect to 100 parts by mass of the (meth)acrylic polymer 1. Further, when the pressure-sensitive adhesive composition 2 of the present invention contains a cross-linking agent, its content is not particularly limited. 0.01 to 5 parts by mass per 100 parts by mass of the (meth)acrylic polymer 2 and the polymerizable monomer M). In this case, the adhesive sheet tends to have high adhesive strength. The content of the crosslinking agent is 100 parts by mass of the (meth)acrylic polymer 2 (however, when the polymerizable monomer M described later is included, the total mass of the (meth)acrylic polymer 2 and the polymerizable monomer M is 100 It is preferably 0.05 to 1 part by mass. The cross-linking agents may be used alone or in combination of two or more.

The pressure-sensitive adhesive composition of the present invention can also contain polyfunctional monomers. In this case, by curing the adhesive composition by UV irradiation, the polymer component in the adhesive layer can form a crosslinked structure, whereby the adhesive sheet tends to have excellent adhesive strength. Polyfunctional monomers can include, for example, a wide range of known polyfunctional monomers used to obtain pressure-sensitive adhesive sheets. When the pressure-sensitive adhesive composition contains a polyfunctional monomer, it also preferably contains a photopolymerization initiator described later. As used herein, polyfunctional monomers do not include metal salts of the unsaturated group-containing monomers and cross-linking agents.

Examples of polyfunctional monomers include compounds having two or more polymerizable double bonds in the molecule. The number of polymerizable double bonds in the polyfunctional monomer is 2 or more, preferably 2 or more and less than 5, more preferably 2 or more and less than 4.

Polyfunctional monomers include, for example, bifunctional monomers (monomers having two polymerizable double bonds) such as polyethylene glycol diacrylate, polypropylene diacrylate, alkyl diacrylate, and polytetramethylene glycol diacrylate. , polypropylene glycol diacrylate, dioxane diacrylate, tricyclodecanol diacrylate, fluorene diacrylate. Further, as polyfunctional monomers, tri- or more functional monomers such as alkoxylated trimethylolpropane triacrylate, alkoxylated glycerin triacrylate, caprolactone-modified isocyanurate triacrylate, pentaerythritol acrylate, alkoxylated pentaerythritol acrylate, ( Alkoxylated) pentaerythritol acrylate, (alkoxylated) ditrimethylolpropane acrylate, (alkoxylated) dipentaerythritol acrylate, (ethoxylated) polyglycerin acrylate and the like can be mentioned.

The polyfunctional monomer is preferably a polyfunctional monomer having an alkylene glycol group in one molecule. In this case, the number of alkylene glycol groups in one molecule is preferably 1-20. Examples of such polyfunctional monomers include polyethylene glycol diacrylate, trimethylolpropane propylene oxide-modified triacrylate, and the like.

A commercial item can be used for a polyfunctional monomer, for example. Commercially available products include Shin-Nakamura Chemical's bifunctional polyethylene glycol acrylate NK ester series "A-200" (polyethylene glycol #200 diacrylate), "A-400" (polyethylene glycol #400 diacrylate), Toa Trifunctional monomer M310 (trimethylolpropane PO-modified triacrylate) and trifunctional monomer M321 (trimethylolpropane propylene oxide-modified triacrylate) manufactured by Gosei Co., Ltd., and bifunctional monomer M211B (bisphenol A EO-modified diacrylate) manufactured by Toagosei Co., Ltd. etc.

The polyfunctional monomer may have a bisphenol skeleton in one molecule. By using a polyfunctional monomer having a bisphenol skeleton in one molecule, the hardness of the pressure-sensitive adhesive layer can be more effectively increased, and the workability of the pressure-sensitive adhesive sheet can be easily improved. Examples of such polyfunctional monomers include bisphenol A diglycidyl ether diacrylate, propoxylated bisphenol A diacrylate, bisphenol F diglycidyl ether diacrylate, and the like.

When the pressure-sensitive adhesive composition 1 of the present invention contains a polyfunctional monomer, the content is not particularly limited, for example, 0.01 to 20 parts by mass are used with respect to 100 parts by mass of the (meth)acrylic polymer 1. can do. In this case, the adhesive sheet tends to have high adhesive strength. The content of the polyfunctional monomer is preferably 0.05 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, based on 100 parts by mass of the (meth)acrylic polymer 1. Further, when the pressure-sensitive adhesive composition 2 of the present invention contains a polyfunctional monomer, 100 parts by mass of the (meth)acrylic polymer 2 (however, when the polymerizable monomer M described later is included, the (meth)acrylic polymer 2 and the polymerizable monomer M (100 parts by mass), 0.01 to 20 parts by mass can be used. In this case, the adhesive sheet tends to have high adhesive strength. 100 parts by mass of the (meth)acrylic polymer 2 (however, when the polymerizable monomer M described later is included, the total mass of the (meth)acrylic polymer 2 and the polymerizable monomer M is 100 parts by mass), The content of the polyfunctional monomer is preferably 0.05 to 10 parts by mass, more preferably 0.1 to 5 parts by mass. Polyfunctional monomers may be used alone or in combination of two or more.

The pressure-sensitive adhesive composition of the present invention can also contain both a cross-linking agent and a multifunctional monomer.

The adhesive composition of the present invention can also contain a photopolymerization initiator.

As the photopolymerization initiator, for example, a wide range of known photopolymerization initiators can be used, and among them, an acetophenone-based photopolymerization initiator or an acylphosphine oxide-based photopolymerization initiator is preferable.

Specific examples of acetophenone-based initiators include diethoxyacetophenone, benzyldimethylketal, oligo(2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenylpropanone], 2,2-dimethoxy-2 -phenylacetophenone, (1-hydroxycyclohexylphenylketone, 2-hydroxy-2-methyl-1-phenylpropanone, etc. Specific examples of benzoin ether initiators include benzoin, benzoin methyl ether, and the like. be done.

Specific examples of acylphosphine oxide initiators include phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide and the like.

Other examples of photopolymerization initiators include benzoin ether-based initiators, benzophenone-based initiators, hydroxyalkylphenone-based initiators, thioxanthone-based initiators, and amine-based initiators.

When the pressure-sensitive adhesive composition of the present invention contains a photopolymerization initiator, its content is not particularly limited, for example, 0.05 to 10 parts by weight per 100 parts by weight of the (meth)acrylic polymer can be used, It is more preferably 0.1 to 5 parts by mass. A photoinitiator may be used individually by 1 type, or may use 2 or more types together.

The pressure-sensitive adhesive composition of the present invention can further contain a polymerizable monomer M, if necessary. Such a polymerizable monomer M is a monomer other than the polyfunctional monomer, and is, for example, a monofunctional polymerizable monomer.

The type of the polymerizable monomer M is not particularly limited, and examples thereof include monomers similar to the monomer units constituting the (meth)acrylic polymer. The polymerizable monomer M is preferably a mixture containing all the monomers for forming the monomer units that constitute the (meth)acrylic polymer.

Therefore, the polymerizable monomer M is preferably a mixture of the (meth)acrylic acid ester monomer and the hydroxyl group-containing (meth)acrylic monomer. The content ratio of each monomer contained in the polymerizable monomer M is not particularly limited. It is preferred that the ratios correspond to the ratios of the corresponding monomer units in the (meth)acrylic polymer.

When the adhesive composition of the present invention contains the polymerizable monomer M, the content is not particularly limited, for example, per 100 parts by mass of the total mass of the (meth)acrylic polymer 2 and the polymerizable monomer M , 3 to 1000 parts by mass, preferably 5 to 700 parts by mass, more preferably 25 to 500 parts by mass, and particularly preferably 30 to 400 parts by mass.

The pressure-sensitive adhesive composition of the present invention can contain a solvent from the viewpoint of improving coatability. The solvent is not particularly limited, and a wide range of known solvents can be used. When the pressure-sensitive adhesive composition contains a solvent, its content is not particularly limited, for example, it can be 25 to 500 parts by mass, and 30 to 400 parts by mass with respect to 100 parts by mass of the (meth)acrylic polymer. is more preferable. Also, the content of the solvent is preferably 10 to 90% by mass, more preferably 20 to 80% by mass, relative to the total mass of the pressure-sensitive adhesive composition. One type of solvent may be used alone, or two or more types may be used in combination. When two or more types are used in combination, the total mass is preferably within the above range.

In addition, when the pressure-sensitive adhesive composition of the present invention contains the polymerizable monomer M, the polymerizable monomer M can also serve as a solvent.

The pressure-sensitive adhesive composition can contain various additives for pressure-sensitive adhesives other than those described above as long as the effects of the present invention are not impaired. Such additives can be selected from, for example, plasticizers, antioxidants, metal corrosion inhibitors, tackifiers, ultraviolet absorbers, light stabilizers such as hindered amine compounds, and the like, as required. Dyes and pigments may also be added for the purpose of coloring.

As described above, the pressure-sensitive adhesive composition 1 of the present invention contains at least a (meth)acrylic polymer 1 and a silane coupling agent, and optionally a cross-linking agent, a polyfunctional monomer, a photopolymerization initiator, At least one selected from the group consisting of polymerizable monomers M, solvents and other various additives can be included. Further, the pressure-sensitive adhesive composition 2 of the present invention contains at least a (meth)acrylic polymer 2, a metal salt of an unsaturated group-containing monomer, and a silane coupling agent, and if necessary, a cross-linking agent, a polyfunctional At least one selected from the group consisting of a photopolymerizable monomer, a photopolymerization initiator, a polymerizable monomer M, a solvent and other various additives can be included.

As one aspect, the pressure-sensitive adhesive composition 1 of the present invention contains at least a (meth)acrylic polymer 1, a silane coupling agent, and a cross-linking agent, and may contain a solvent as necessary. In this aspect, the pressure-sensitive adhesive composition 1 may be free of polyfunctional monomers, photopolymerization initiators and polymerizable monomers M. Further, the adhesive composition 2 of the present invention, as one aspect, the (meth) acrylic polymer 2, a metal salt of an unsaturated group-containing monomer, a silane coupling agent, a polyfunctional monomer, a photopolymerization initiator and a polymerizable At least the monomer M can be included. In this aspect, the adhesive composition 2 may not contain a cross-linking agent.

The method for preparing the pressure-sensitive adhesive composition of the present invention is not particularly limited. For example, a (meth) acrylic polymer synthesized in advance, a silane coupling agent, a metal salt of the unsaturated group-containing monomer, and optionally other components (e.g., the cross-linking agent, polyfunctional monomer, A pressure-sensitive adhesive composition can be prepared by mixing at least one selected from the group consisting of a photopolymerization initiator, a polymerizable monomer M, a solvent and other various additives in a predetermined ratio. In this case, the (meth)acrylic polymer can be used in the form of a solution or dispersion. When the (meth)acrylic polymer is a solution or dispersion, the solution or dispersion may contain the solvent, and may contain the polymerizable monomer M instead of or together with the solvent. When the (meth)acrylic polymer is a solution or dispersion, the solid content concentration can be, for example, 1 to 50% by mass.

2. Adhesive sheet (adhesive layer)
A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer can be formed by using the pressure-sensitive adhesive composition of the present invention. The pressure-sensitive adhesive layer can be formed by curing the pressure-sensitive adhesive composition, that is, the pressure-sensitive adhesive layer is formed from the cured product of the pressure-sensitive adhesive composition of the present invention. The method for forming the pressure-sensitive adhesive layer is not particularly limited, and for example, the same method as for the known pressure-sensitive adhesive layer can be adopted.

Specifically, a method (hereinafter abbreviated as "Method A") comprising a step of applying a pressure-sensitive adhesive composition on a substrate to form a coating film, and a step of heat-treating the coating film, An adhesive layer can be formed. Alternatively, a method (hereinafter abbreviated as "Method B") comprising a step of applying the pressure-sensitive adhesive composition on a substrate to form a coating film, and a step of irradiating the coating film with an active energy ray, A pressure-sensitive adhesive layer can be formed by curing the pressure-sensitive adhesive composition.

In method A and method B, the coating of the pressure-sensitive adhesive composition can be carried out using a known coating apparatus. Coating devices include, for example, blade coaters, air knife coaters, roll coaters, bar coaters, gravure coaters, micro gravure coaters, rod blade coaters, lip coaters, die coaters and curtain coaters.

In method A and method B, the substrate used for coating the pressure-sensitive adhesive composition is not particularly limited. For example, the pressure-sensitive adhesive composition can be applied to various substrates such as resin substrates and glass substrates. When the substrate has a release sheet as described later, the adhesive composition can be applied onto the release sheet. Also, the pressure-sensitive adhesive composition can be directly applied onto the member to be adhered.

In Method A and Method B, the thickness of the pressure-sensitive adhesive composition after coating is not particularly limited, either, and can be appropriately set according to the desired thickness of the pressure-sensitive adhesive layer.

In Method A, the step of heat-treating the coating film can employ, for example, a step similar to a known method. By such heat treatment, curing of the pressure-sensitive adhesive composition progresses and volatile matter disappears to form a cured product. For example, when the pressure-sensitive adhesive composition contains the cross-linking agent, the reaction between the (meth)acrylic polymer and the cross-linking agent proceeds to form a crosslinked body of the (meth)acrylic polymer. Thereby, the strength of the pressure-sensitive adhesive layer can be improved, and the adhesive force can also be improved. Therefore, when the pressure-sensitive adhesive composition contains a cross-linking agent, the method A is preferably used to form the pressure-sensitive adhesive layer.

In method A, in the step of heat-treating the coating film, the heating temperature can be, for example, 50° C. or higher and 150° C. or lower, and the heating time depends on the heating temperature and the target residual solvent concentration of the adhesive layer. The time can be set as appropriate, for example, 1 to 30 minutes. For the heat treatment, a known heating device such as a heating furnace or an infrared lamp can be used. After the heat treatment, if necessary, the cured product can be subjected to aging treatment under a predetermined environment.

In method B, the step of irradiating the coating film with an active energy ray can employ, for example, a step similar to a known method. Through such a process, for example, the photopolymerizable component in the pressure-sensitive adhesive composition is cured to form a cured product. For example, when the pressure-sensitive adhesive composition contains the polyfunctional monomer and the photopolymerization initiator, the polymerization reaction of the polyfunctional monomer also proceeds. Thereby, the strength of the pressure-sensitive adhesive layer can be improved, and the adhesive force can also be improved. Therefore, when the pressure-sensitive adhesive composition contains a polyfunctional monomer in addition to the (meth)acrylic polymer, it is preferable to form the pressure-sensitive adhesive layer by method B, and the pressure-sensitive adhesive composition has a functional group (meth) It is particularly preferred to employ Method B when including a polyfunctional monomer, a photoinitiator and a polymerizable monomer M in addition to the acrylic polymer.

In method B, the active energy rays include ultraviolet rays, electron rays, visible rays, X-rays, ion rays, etc., and can be appropriately selected according to the photopolymerization initiator contained in the pressure-sensitive adhesive layer. Among them, from the viewpoint of versatility, ultraviolet rays or electron beams are preferable, and ultraviolet rays are particularly preferable. As the ultraviolet light source, for example, chemical lamps, high-pressure mercury lamps, low-pressure mercury lamps, ultrahigh-pressure mercury lamps, metal halide lamps, carbon arcs, xenon arcs, electrodeless ultraviolet lamps, and the like can be used. The irradiation output of ultraviolet rays is preferably such that the integrated light amount is 100 to 10000 mJ/cm ² , more preferably 500 to 5000 mJ/cm ² .

The pressure-sensitive adhesive layer formed by methods such as Method A and Method B may be protected on one side or both sides thereof with a protective layer such as a protective sheet, if necessary.

The thickness of the pressure-sensitive adhesive layer can be appropriately set according to the application, and is not particularly limited. For example, the thickness of the adhesive layer is preferably 10-1000 μm, more preferably 20-500 μm, even more preferably 100-400 μm. In particular, since the pressure-sensitive adhesive layer is formed from the pressure-sensitive adhesive composition of the present invention, it has high transparency, and high transparency can be maintained even if the pressure-sensitive adhesive layer is thickened. In addition, the thickness of an adhesive layer means the sum total of the thickness of each layer, when an adhesive layer has a multilayer laminated structure.

The gel fraction of the pressure-sensitive adhesive layer is not particularly limited. For example, it is preferably 30 to 99%, more preferably 50 to 95%, in terms of easily having excellent adhesive strength.

The gel fraction of the pressure-sensitive adhesive layer is a value measured by the following method. First, about 0.1 g of the adhesive sheet (adhesive layer) is collected in a sample bottle, 30 ml of ethyl acetate is added, and shaken for 24 hours. Thereafter, the contents of the sample bottle are filtered through a 200-mesh stainless wire mesh, and the residue on the wire mesh is dried at 120° C. for 1 hour to measure the dry mass (g). From the obtained dry mass, the following formula 1
Gel fraction (% by mass) = (dry mass/collected mass of pressure-sensitive adhesive layer) x 100 Equation 1
The gel fraction can be obtained by

(adhesive sheet)
The pressure-sensitive adhesive sheet of the present invention includes the pressure-sensitive adhesive layer. The structure of such a pressure-sensitive adhesive sheet is not particularly limited as long as it has the pressure-sensitive adhesive layer, and for example, it may have the same structure as a known pressure-sensitive adhesive sheet. The pressure-sensitive adhesive sheet can be a single-layer pressure-sensitive adhesive sheet composed only of the pressure-sensitive adhesive layer. Alternatively, the adhesive sheet can be an adhesive sheet with a substrate on one side or both sides. The adhesive sheet may be either a single-sided adhesive sheet or a double-sided adhesive sheet.

When the pressure-sensitive adhesive sheet is provided with a substrate on one side or both sides, the substrate is not particularly limited. material can be mentioned. As the transparent substrate, general films used in the optical field such as polyethylene terephthalate film, acrylic film, polycarbonate film, triacetyl cellulose film, and cycloolefin polymer film can be used. Further, an easy-adhesion layer may be provided on the pressure-sensitive adhesive layer side of these transparent substrates. Furthermore, a functional layer such as a hard coat layer, an antireflection layer, an antifouling layer, or an ultraviolet absorption layer may be provided on the opposite side of the transparent substrate from the pressure-sensitive adhesive layer.

Specific examples of the adhesive sheet include a single-layer adhesive sheet consisting of an adhesive layer, a multilayer adhesive sheet having a plurality of laminated adhesive layers, and a multilayer adhesive sheet having another adhesive layer laminated between adhesive layers. multi-layer pressure-sensitive adhesive sheet in which a support is laminated between pressure-sensitive adhesive layers, and a multi-layer pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive layer is laminated on one side of a support and another pressure-sensitive adhesive layer is laminated on the other side An adhesive sheet is mentioned. When the pressure-sensitive adhesive sheet has a support, the support may be of the same type as the transparent substrate, for example.

Moreover, the pressure-sensitive adhesive sheet of the present invention can include a pressure-sensitive adhesive sheet with a release sheet provided with release sheets on both sides. The pressure-sensitive adhesive sheet with a release sheet can have a pair of release sheets with different release forces on both sides of the pressure-sensitive adhesive sheet.

As the release sheet, a release laminated sheet having a release sheet base material and a release agent layer provided on one side of the release sheet base material, or a polyolefin film such as a polyethylene film or a polypropylene film as a low-polarity base material. is mentioned.

Papers and polymer films are used as the base material for the release sheet in the release laminated sheet. As the release agent constituting the release agent layer, for example, a general-purpose addition-type or condensation-type silicone-based release agent or a compound containing a long-chain alkyl group is used. In particular, an addition-type silicone-based release agent having high reactivity is preferably used. Specific examples of silicone release agents include BY24-4527 and SD-7220 manufactured by Toray Dow Corning Silicone Co., Ltd., and KS-3600, KS-774 and X62-2600 manufactured by Shin-Etsu Chemical Co., Ltd. be done. In addition, the silicone release agent may contain a silicone resin which is an organic silicon compound having SiO ₂ units and (CH ₃ ) ₃ SiO _1/2 units or CH ₂ ═CH(CH ₃ ) SiO _1/2 units. preferable. Specific examples of silicone resins include BY24-843, SD-7292, SHR-1404, etc. manufactured by Dow Corning Toray Silicone Co., Ltd., and KS-3800, X92-183, etc. manufactured by Shin-Etsu Chemical Co., Ltd.

A commercially available product may be used as the peelable laminate sheet. For example, a release-treated polyethylene terephthalate film manufactured by Teijin DuPont Films Limited, a heavy separator film, and a release-treated polyethylene terephthalate film manufactured by Teijin DuPont Films Limited, a light separator film can be used.

Since the pressure-sensitive adhesive sheet of the present invention includes the pressure-sensitive adhesive layer formed from the above-described pressure-sensitive adhesive composition, it has high adhesive strength and is also excellent in outgas resistance. In particular, the pressure-sensitive adhesive sheet of the present invention has excellent adhesive strength to substrates formed of glass and various resins, and in particular, the adhesive strength to glass is superior to that of conventional adhesive sheets. It can exhibit excellent adhesion even to adherends coated with metal oxides.

The adhesive strength of the adhesive sheet to glass is a value measured by the following method. The surface of the adhesive sheet on the adhesive layer side is attached to a 75 μm thick polyester film (Toyobo A4300) that has been treated for easy adhesion, and the part to be attached to the adherend (float glass described later) is 25 mm wide and 25 mm long. A measurement sample is obtained by cutting to 80 mm. This sample is attached to a float glass having a thickness of 1 mm, a width of 115 mm, and a length of 75 mm in a width of 25 mm and a length of 50 mm, and then press-bonded by reciprocating twice with a roller of 2 kg. After that, it is treated in an autoclave at a temperature of 30° C. and a pressure of 0.5 MPa for 30 minutes, and then left to stand for one day at an atmospheric pressure and a temperature of 23° C. and a humidity of 50%. Then, the adhesive strength of the sample including the adherend is measured under the same environment by AGX-500NX of Shimadzu Corporation while the unbonded portion of the adhesive sheet is gripped and pulled in the direction of 180° C. at a pulling speed of 300 mm/min. Let the value obtained by this measurement be the adhesive strength of the adhesive sheet to glass.

The method for producing the pressure-sensitive adhesive sheet of the present invention is not particularly limited, and for example, a wide variety of known pressure-sensitive adhesive sheet production methods can be employed.

The pressure-sensitive adhesive sheet of the present invention can be suitably used for bonding optical members, for example. That is, the pressure-sensitive adhesive sheet of the present invention can be used as an optical pressure-sensitive adhesive sheet. Examples of optical members include constituent members in optical products such as touch panels and image display devices. Examples of constituent members of the touch panel include an ITO film in which an ITO film is provided on a transparent resin film, an ITO glass in which an ITO film is provided on the surface of a glass plate, a transparent conductive film in which a transparent resin film is coated with a conductive polymer, Examples include hard coat films and anti-fingerprint films. Examples of constituent members of the image display device include antireflection films, oriented films, polarizing films, retardation films, brightness enhancement films and the like used in liquid crystal display devices. Moreover, the pressure-sensitive adhesive sheet of the present invention may be used for bonding modules such as a liquid crystal module and a touch panel module. The optical member can be made of materials such as glass, polycarbonate, polyethylene terephthalate, polymethyl methacrylate, polyethylene naphthalate, cycloolefin polymer, triacetyl cellulose, polyimide, and cellulose acylate.

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the embodiments of these examples.

(Production example 1)
350 g of n-butyl acrylate (BA), 150 g of 2-hydroxyethyl acrylate (2HEA), 750 g of ethyl acetate, and a metal salt of an unsaturated group-containing monomer are placed in a 2 L flask equipped with a stirrer, nitrogen inlet tube, condenser, and thermometer. After adding 2.5 parts by mass of Asada Chemical Industry's "M-CP" (zinc methacrylate) and 0.2 g of n-dodecyl mercaptan, the contents were replaced with nitrogen at a nitrogen flow rate of 300 ml/min for 60 minutes. After that, the nitrogen flow rate was lowered to 100 ml/min, and the temperature was raised to 70° C. in a water bath for heating. Then, 0.15 g of AIBN (2,2-azobis(isobutyronitrile)) was added and reacted for 2 hours while controlling exotherm, after which 0.5 g of AIBN was added and reacted for another 6 hours. After cooling, a solution containing a (meth)acrylic polymer was obtained. The resulting solution had a solid content concentration of 40% by mass, and the (meth)acrylic polymer had a mass average molecular weight of 600,000.

(Production example 2)
275 g of n-butyl acrylate (BA), 25 g of cyclohexyl acrylate (CHMA), 200 g of 2-hydroxyethyl acrylate (2HEA) and n-dodecyl mercaptan were placed in a 2 L flask equipped with a stirrer, nitrogen inlet, condenser and thermometer. 0.4 g was added, and the mixture was replaced with nitrogen at a nitrogen flow rate of 300 ml/min for 60 minutes. After that, the nitrogen flow rate was lowered to 100 ml/min, and the temperature was raised to 60° C. in a water bath for heating. Next, 0.15 g of AIBN was added and reacted for 30 minutes while controlling heat generation, followed by cooling to obtain a solution containing a (meth)acrylic polymer. To this solution, the above-described acrylic monomers, that is, BA, CHMA, and 2HEA, were put into a flask at a mass ratio of 55:5:40, and an acrylic syrup having a solid content concentration of 20% by mass and a weight average molecular weight of 400,000 was added. Obtained.

(Production example 3)
260 g of 2-ethylhexyl acrylate (2EHA), 45 g of cyclohexyl acrylate (CHMA), 190 g of 4-hydroxybutyl acrylate (4HBA), acrylic acid (AA ) and 0.4 g of n-dodecylmercaptan were added, and the mixture was replaced with nitrogen at a nitrogen flow rate of 300 ml/min for 60 minutes. After that, the nitrogen flow rate was lowered to 100 ml/min, and the temperature was raised to 60° C. in a water bath for heating. Next, 0.15 g of AIBN was added and reacted for 30 minutes while controlling heat generation, followed by cooling to obtain a solution containing a (meth)acrylic polymer. To this solution, the above-described acrylic monomers, that is, 2EHA, CHMA, 4HBA, and AA were added in a flask at a mass ratio of 52:9:38:1, and the solid content concentration was 20% by mass and the weight average molecular weight was 400,000. An acrylic syrup was obtained.

(Production example 4)
275 g of n-butyl acrylate (BA), 50 g of cyclohexyl acrylate (CHMA), 175 g of 4-hydroxybutyl acrylate (4HBA) and n-dodecyl mercaptan were placed in a 2 L flask equipped with a stirrer, nitrogen inlet, condenser and thermometer. 0.4 g was added, and the mixture was replaced with nitrogen at a nitrogen flow rate of 300 ml/min for 60 minutes. After that, the nitrogen flow rate was lowered to 100 ml/min, and the temperature was raised to 60° C. in a water bath for heating. Next, 0.15 g of AIBN was added and reacted for 30 minutes while controlling heat generation, followed by cooling to obtain a solution containing a (meth)acrylic polymer. To this solution, the above-described acrylic monomers, that is, BA, CHMA, and 4HBA, were put into a flask at a mass ratio of 55:10:35, and an acrylic syrup having a solid content concentration of 20% by mass and a weight average molecular weight of 400,000 was added. Obtained.

(Production example 5)
350 g of n-butyl acrylate (BA), 50 g of cyclohexyl acrylate (CHMA), 100 g of 4-hydroxybutyl acrylate (4HBA) and n-dodecyl mercaptan were placed in a 2 L flask equipped with a stirrer, nitrogen inlet, condenser and thermometer. 0.4 g was added, and the mixture was replaced with nitrogen at a nitrogen flow rate of 300 ml/min for 60 minutes. After that, the nitrogen flow rate was lowered to 100 ml/min, and the temperature was raised to 60° C. in a water bath for heating. Next, 0.15 g of AIBN was added and reacted for 30 minutes while controlling heat generation, followed by cooling to obtain a solution containing a (meth)acrylic polymer. To this solution, the above-described acrylic monomers, that is, BA, CHMA, and 4HBA, were put into a flask at a mass ratio of 70:10:20, and an acrylic syrup having a solid content concentration of 20% by mass and a weight average molecular weight of 400,000 was added. Obtained.

(Production example 6)
475 g of 2-ethylhexyl acrylate (2EHA), 25 g of 2-hydroxyethyl acrylate (2HEA), and 0.4 g of n-dodecyl mercaptan were charged into a 2 L flask equipped with a stirrer, nitrogen inlet tube, condenser, and thermometer, and nitrogen was added. Nitrogen substitution was performed for 60 minutes at a flow rate of 300 ml/min. After that, the nitrogen flow rate was lowered to 100 ml/min, and the temperature was raised to 60° C. in a water bath for heating. Next, 0.15 g of AIBN was added and reacted for 30 minutes while controlling heat generation, followed by cooling to obtain a solution containing a (meth)acrylic polymer. To this solution, 2EHA and 2HEA were added to the flask at a mass ratio of 95:5 to obtain an acrylic syrup having a solid concentration of 20% by mass and a weight average molecular weight of 400,000.

(Example 1)
A pressure-sensitive adhesive composition was prepared according to the blending amounts (parts by mass) shown in Table 1 below. Specifically, to 100 parts by mass of the (meth)acrylic polymer obtained in Production Example 1 (in terms of polymer component), 0.3 parts by mass of "Coronate L" (manufactured by Tosoh), which is an isocyanate cross-linking agent as a cross-linking agent, Silane cup As a ring agent, 1 part by mass of "KBM-5103" manufactured by Shin-Etsu Chemical Co., Ltd. was added, and the mixture was stirred and defoamed to obtain a pressure-sensitive adhesive composition 1 as a coating liquid. This coating solution is coated on a 50 μm polyester film coated with a silicone release agent so that the thickness of the adhesive layer after drying is 58 μm, and dried at a dryer temperature of 80 ° C. for 2 minutes to remove the adhesive layer. Obtained. Three adhesive layers of 58 µm each were laminated, pressed with a roller, and allowed to stand at room temperature for 7 days to obtain a pressure-sensitive adhesive sheet with a thickness of 175 µm.

(Example 2)
A pressure-sensitive adhesive composition was prepared according to the blending amounts (parts by mass) shown in Table 1 below. Specifically, the acrylic syrup obtained in Production Example 2 was weighed to 100 parts by mass. The acrylic syrup and IGM RESUNS B.I. V. 0.3 parts by mass of "EsacureOne" manufactured by the company, "A-200" (polyethylene glycol #200 diacrylate) manufactured by Shin-Nakamura Chemical Co., Ltd. as a polyfunctional monomer, and 0.3 parts by mass of Shin-Nakamura Chemical Co., Ltd. as a silane coupling agent " 0.5 parts by mass of "KBM-403" and 0.2 parts by mass of Asada Chemical Industry's "R-MMA2" (magnesium methacrylate) as a metal salt of an unsaturated group-containing monomer are added and stirred and degassed to form an adhesive. Composition 2 was obtained as a coating liquid. This coating solution was applied onto a 50 μm polyester film coated with a silicone release agent so that the adhesive layer had a thickness of 175 μm, and a 50 μm polyester film coated with a silicone release agent was further coated thereon. piled up. Then, after irradiation with a chemical lamp at a light intensity of 7 mW/cm ² for 2 minutes, irradiation was performed with a high-pressure mercury lamp so that the integrated light amount was 1500 mJ/cm ² to obtain a pressure-sensitive adhesive sheet with a thickness of 175 μm.

(Example 3)
A pressure-sensitive adhesive composition was prepared according to the blending amounts (parts by mass) shown in Table 1 below. Specifically, the acrylic syrup obtained in Production Example 3 was weighed to 100 parts by mass. The acrylic syrup and IGM RESUNS B.I. V. 0.3 parts by mass of "EsacureOne" manufactured by the company, "A-200" (polyethylene glycol # 200 diacrylate) manufactured by Shin-Nakamura Chemical Co., Ltd. as a polyfunctional monomer, and 0.35 parts by mass of Shin-Nakamura Chemical Co., Ltd. as a silane coupling agent " KBM-5103” 1 part by mass, and Asada Kagaku Kogyo “S-MA” (sodium methacrylate) 0.2 parts by mass as a metal salt of an unsaturated group-containing monomer are added and stirred to defoam the pressure-sensitive adhesive composition. 2 was obtained as a coating liquid. This coating solution was applied onto a 50 μm polyester film coated with a silicone release agent so that the adhesive layer had a thickness of 175 μm, and a 50 μm polyester film coated with a silicone release agent was further coated thereon. piled up. Then, after irradiation with a chemical lamp at a light intensity of 7 mW/cm ² for 2 minutes, irradiation was performed with a high-pressure mercury lamp so that the integrated light amount was 1500 mJ/cm ² to obtain a pressure-sensitive adhesive sheet with a thickness of 175 μm.

(Comparative example 1)
A pressure-sensitive adhesive composition was prepared according to the blending amounts (parts by mass) shown in Table 1 below. Specifically, the acrylic syrup obtained in Production Example 4 was weighed to 100 parts by mass. The acrylic syrup and IGM RESUNS B.I. V. 0.3 parts by mass of "EsacureOne" manufactured by the company, "A-200" (polyethylene glycol #200 diacrylate) manufactured by Shin-Nakamura Chemical Co., Ltd. as a polyfunctional monomer, and 0.3 parts by mass of Shin-Nakamura Chemical Co., Ltd. as a silane coupling agent " KBM-5103” (1 part by mass) was added and defoamed with stirring to obtain a pressure-sensitive adhesive composition as a coating liquid. This coating solution was applied on a 50 μm polyester film coated with a silicone release agent so that the thickness of the adhesive layer after drying was 175 μm, and furthermore, a 50 μm thick film coated with a silicone release agent was applied. overlaid with polyester film. Then, after irradiation with a chemical lamp at a light intensity of 7 mW/cm ² for 2 minutes, irradiation was performed with a high-pressure mercury lamp so that the integrated light amount was 1500 mJ/cm ² to obtain a pressure-sensitive adhesive sheet with a thickness of 175 μm.

(Comparative example 2)
A pressure-sensitive adhesive composition was prepared according to the blending amounts (parts by mass) shown in Table 1 below. Specifically, the acrylic syrup obtained in Production Example 5 was weighed to 100 parts by mass. The acrylic syrup and IGM RESUNS B.I. V. 0.3 parts by mass of "EsacureOne" manufactured by Co., Ltd., 0.3 parts by mass of "A-200" (polyethylene glycol #200 diacrylate) manufactured by Shin-Nakamura Chemical Co., Ltd. as a polyfunctional monomer, and Asada as a metal salt of an unsaturated group-containing monomer Chemical industrial grade "M-CP" (zinc methacrylate) of 0.5 parts by mass was added and defoamed with stirring to obtain a pressure-sensitive adhesive composition as a coating liquid. This coating solution was applied onto a 50 μm polyester film coated with a silicone release agent so that the adhesive layer had a thickness of 175 μm, and a 50 μm polyester film coated with a silicone release agent was further coated thereon. piled up. Then, after irradiation with a chemical lamp at a light intensity of 7 mW/cm ² for 2 minutes, irradiation was performed with a high-pressure mercury lamp so that the integrated light amount was 1500 mJ/cm ² to obtain a pressure-sensitive adhesive sheet with a thickness of 175 μm.

(Comparative Example 3)
A pressure-sensitive adhesive composition was prepared according to the blending amounts (parts by mass) shown in Table 1 below. Specifically, the acrylic syrup obtained in Production Example 6 was weighed to 100 parts by mass. The acrylic syrup and IGM RESUNS B.I. V. 0.3 parts by mass of "EsacureOne" manufactured by the company, "A-200" (polyethylene glycol # 200 diacrylate) manufactured by Shin-Nakamura Chemical Co., Ltd. as a polyfunctional monomer, and 0.5 parts by mass of "A-200" (polyethylene glycol # 200 diacrylate) manufactured by Shin-Etsu Chemical as a silane coupling agent. KBM-403" 0.5 parts by mass, Asada Kagaku Kogyo "M-CP" (zinc methacrylate) 1 part by mass as a metal salt of an unsaturated group-containing monomer is added, and the pressure-sensitive adhesive composition is prepared by stirring and defoaming. It was obtained as a coating liquid. This coating solution was applied onto a 50 μm polyester film coated with a silicone release agent so that the adhesive layer had a thickness of 175 μm, and a 50 μm polyester film coated with a silicone release agent was further coated thereon. piled up. Then, after irradiation with a chemical lamp at a light intensity of 7 mW/cm ² for 2 minutes, irradiation was performed with a high-pressure mercury lamp so that the integrated light amount was 1500 mJ/cm ² to obtain a pressure-sensitive adhesive sheet with a thickness of 175 μm.

(Evaluation method)
[Adhesive force]
The surface of the adhesive sheet on the adhesive layer side is attached to a 75 μm thick polyester film (Toyobo A4300) that has been treated for easy adhesion, and the part to be attached to the adherend (float glass described later) is 25 mm wide and 25 mm long. A measurement sample was obtained by cutting to 80 mm. This sample was attached to a float glass having a thickness of 1 mm, a width of 115 mm, and a length of 75 mm in a width of 25 mm and a length of 50 mm, and then crimped by reciprocating twice with a roller of 2 kg. After that, it was treated in an autoclave at a temperature of 30° C. and a pressure of 0.5 MPa for 30 minutes, and then allowed to stand at atmospheric pressure and a temperature of 23° C. and a humidity of 50% for one day. Next, the adhesive strength of the sample including the adherend was measured under the same environment by Shimadzu AGX-500NX while the unbonded portion of the adhesive sheet was gripped and pulled in the direction of 180°C at a pulling speed of 300 mm/min. Let the value obtained by this measurement be the adhesive strength of the adhesive sheet to glass.

[Outgas resistance]
The surface of the adhesive layer side of the adhesive sheet is attached to a polycarbonate resin plate (Mitsubishi Gas Chemical Iupilon MR58) with a thickness of 1 mm and 60 mm × 80 mm, and then the polyester film is peeled off. A glass plate having a size of 1 mm and a size of 55 mm×75 mm was attached to the entire surface. Thus, a laminate sample composed of polycarbonate resin plate/adhesive layer/glass plate was obtained. The laminate sample was treated in an autoclave at 30 ° C. and 0.5 MPa for 30 minutes, left overnight, and then placed in an environment of 85 ° C. and relative humidity of 85%. , the sample was visually observed, and air bubbles, floating and peeling were evaluated according to the following three criteria.
◯: No air bubbles, floating, or peeling was observed.
Δ: Microbubbles were observed.
x: Bubbles, floating and peeling were observed.

Table 1 shows the results of each evaluation in addition to the production conditions for the pressure-sensitive adhesive sheets of the above Examples and Comparative Examples. The amount of each monomer component in "(meth)acrylic polymer" in Table 1 means the total amount of (meth)acrylic polymer and monomer in the acrylic syrup when the pressure-sensitive adhesive sheet is produced using acrylic syrup.

From Table 1, it was found that the pressure-sensitive adhesive sheets obtained in Examples had high adhesive strength to glass plates and excellent outgassing resistance. On the other hand, in the adhesive sheets of Comparative Examples 1 to 3, the (meth)acrylic polymer or the adhesive composition does not contain the metal salt of the unsaturated group-containing monomer, so the adhesive strength to the glass plate is low, and the outgas resistance is also good. was inferior.

Claims (7)

(Meth) acrylic polymer and a silane coupling agent,
The (meth)acrylic polymer includes (meth)acrylic acid ester monomer units, (meth)acrylic monomer units having hydroxyl groups, and metal salts of unsaturated group-containing monomer units,
The pressure-sensitive adhesive composition, wherein the (meth)acrylic polymer contains 10% by mass or more of (meth)acrylic monomer units having a hydroxyl group. A (meth) acrylic polymer, a silane coupling agent, and a metal salt of an unsaturated group-containing monomer,
The (meth)acrylic polymer includes (meth)acrylic acid ester monomer units and hydroxyl group-containing (meth)acrylic monomer units,
The pressure-sensitive adhesive composition, wherein the (meth)acrylic polymer contains 10% by mass or more of (meth)acrylic monomer units having a hydroxyl group. The adhesive composition according to claim 1 or 2, wherein the metal salt of the unsaturated group-containing monomer has one or more radically polymerizable unsaturated bonds. The adhesive composition according to any one of claims 1 to 3, further comprising a polyfunctional monomer. The adhesive composition according to any one of claims 1 to 4, further comprising a cross-linking agent. The adhesive composition according to any one of claims 1 to 5, further comprising a photopolymerization initiator. A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer containing a cured product of the pressure-sensitive adhesive composition according to any one of claims 1 to 6.