WO2020230774A1 - Adhesive composition, adhesive sheet and laminate body - Google Patents

Abstract

An adhesive composition is provided which can achieve good metal corrosion prevention, UV ray absorption, reworking, step filling , adhesive strength, and holding strength properties. The present invention pertains to an adhesive composition that contains a copolymer of a non-crosslinkable monomer and a crosslinking monomer having a functional group, a crosslinking agent, and a UV light-absorbing agent. The copolymer includes, as a unit constituted from the non-crosslinkable monomer, a monomer-derived unit having a glass transition temperature of more than –60°C and no more than –20°C. The amount of monomer-derived units in the copolymer that is a unit constituted by the non-crosslinkable monomer and has a glass transition temperature of at least 0°C when a homopolymer is no more than 10% by mass. The weight average molecular weight of the copolymer is no more than 650,000 and the UV light-absorbing agent is either liquid or oil at 23°C.

Description

Adhesive composition, adhesive sheet and laminate

The present invention relates to an adhesive composition, an adhesive sheet and a laminate.

In recent years, display devices such as liquid crystal displays (LCDs) and devices that combine display devices such as touch panels and input devices have been widely used in various fields. Among them, the capacitive touch panel has rapidly become widespread due to its functionality, and is particularly used in mobile phones, smartphones, and the like. In the manufacture of mobile phones, smartphones, etc., adhesive sheets are used for bonding optical members.

As a pressure-sensitive adhesive composition constituting the pressure-sensitive adhesive sheet, a pressure-sensitive adhesive composition containing a polymer and a cross-linking agent is known (see Patent Documents 1 to 6).

Patent Document 1 describes an optical pressure-sensitive adhesive containing an acrylic polymer and an ultraviolet absorber having an absorption maximum wavelength at a wavelength of 350 nm or more, wherein the ultraviolet absorber is at least one oily or liquid compound at 23 ° C. An optical pressure-sensitive adhesive containing 3 to 8 parts by mass with respect to 100 parts by mass of the solid content of the pressure-sensitive adhesive is described.

Patent Document 2 describes an acrylic pressure-sensitive adhesive composition containing an acrylic resin (A) and an ultraviolet absorber (B) having an absorption maximum wavelength of 345 nm or more, wherein the acrylic resin (A) is described. An acrylic adhesive that is an acrylic resin that does not substantially contain an acidic group, and the content of the ultraviolet absorber (B) is 3 to 9 parts by mass with respect to 100 parts by mass of the acrylic resin (A). The composition is described.

Patent Document 3 describes a pressure-sensitive adhesive composition containing a pressure-sensitive adhesive component containing a hydroxy group, a cross-linking agent capable of reacting with the hydroxy group, and an ultraviolet absorber having no hydroxy group, and has a wavelength of 350 nm. An optical foil-like pressure-sensitive adhesive having a light transmittance of 10% or less is described.

Patent Document 4 describes about 60 to about 95 parts by mass of an alkyl acrylate having 1 to 14 carbon atoms in an alkyl group, 0 to about 5 parts by mass of a copolymerizable polar monomer, and less than 400. A laminate containing a pressure-sensitive adhesive composition derived from a precursor containing about 5 to 50 parts by mass of a hydroxy group-containing monomer having an equal amount of OH is described.

In Patent Document 5, the pressure-sensitive adhesive layer contains an acrylic polymer (A), the acrylic polymer (A) is composed of methyl methacrylate and a hydroxyl group-containing monomer as essential monomer components, and the acrylic polymer (A) is described. The content of the hydroxyl group-containing monomer in the total amount (100% by weight) of the constituent monomer components is 10 to 40% by weight, and the carboxy group-containing monomer is substantially not contained as the monomer component constituting the acrylic polymer (A). A pressure-sensitive adhesive sheet having a gel content of the pressure-sensitive adhesive layer of 70 to 100% by weight is disclosed.

Patent Document 6 describes a pressure-sensitive adhesive containing an acrylic copolymer (A), a polyisocyanate-based curing agent (B), and a silane coupling agent (C), wherein the acrylic copolymer (A) is , 20 to 90% by weight of an ethylenically unsaturated monomer (A1) having an alkyl group having an SP value of 8 or more and less than 9.00, and an ethylenically unsaturated monomer having an SP value of 9.00 or more and 15 or less. A pressure-sensitive adhesive obtained by radically polymerizing 10 to 80% by weight of a monomer (A2) is disclosed.

Japanese Unexamined Patent Publication No. 2012-014043 Japanese Unexamined Patent Publication No. 2014-196377 Japanese Unexamined Patent Publication No. 2012-207055 Special Table 2012-504512 Japanese Unexamined Patent Publication No. 2013-104006 Japanese Unexamined Patent Publication No. 2013-127012

Since mobile phones and smartphones are used outdoors and exposed to sunlight, the adhesive layer and adhesive sheet formed from the adhesive composition are used for the purpose of preventing deterioration of the members inside the mobile phone and smartphone products. May be required to absorb UV light.
Further, in the manufacture of mobile phones, smartphones and the like, the pressure-sensitive adhesive layer and the pressure-sensitive adhesive sheet may be bonded to an ITO (Indium Tin Oxide) electrode or a metal mesh electrode. In this case, the ITO electrode or the metal mesh electrode is a pressure-sensitive adhesive. It may be corroded by the acid contained in the layer or adhesive sheet. Therefore, the pressure-sensitive adhesive layer and the pressure-sensitive adhesive sheet are required to have metal corrosion resistance.
Further, when the adhesive sheet is attached to the adherend and then re-peeled (reworked), there is a problem that the adhesive remains on the adherend during the reworking work. The adhesive remaining on the adherend needs to be wiped off with a solvent or washed with a solvent, and the reworking work takes time and effort. Therefore, the pressure-sensitive adhesive layer and the pressure-sensitive adhesive sheet are also required to have reworkability.
In addition, the pressure-sensitive adhesive composition used for a pressure-sensitive adhesive sheet of a mobile phone, a smartphone, or the like is required to have step-following property, adhesive force, and holding power while having these performances.

Here, when the present inventors examined the pressure-sensitive adhesive composition described in Examples of Patent Document 1, it was found that the copolymer contains many units having an acidic group, so that the metal corrosion prevention property is inferior. ..
When the present inventors examined the pressure-sensitive adhesive composition described in Examples of Patent Document 2, the ultraviolet absorber was likely to cause cross-linking inhibition of the copolymer as the main agent, and was inferior in holding power and reworkability. all right.
When the present inventors examined the pressure-sensitive adhesive composition described in Examples of Patent Document 3, ultraviolet rays contained a large amount of an ultraviolet absorber which was solid at 23 ° C. (not liquid or oily) and had no hydroxyl group. It was found that the adhesive strength was inferior because of the expression of absorbency. The pressure-sensitive adhesive composition containing a large amount of an ultraviolet absorber that is solid at 23 ° C. may cause whitening or defects due to compatibility (recrystallization) of the ultraviolet absorber.
On the other hand, Patent Document 4 does not describe an ultraviolet absorber.
Further, when the present inventors examined the pressure-sensitive adhesive compositions described in Examples of Patent Documents 5 and 6, it was found that the step-following property and the reworkability may be inferior.

Therefore, an object to be solved by the present invention is to provide an adhesive composition capable of improving metal corrosion prevention property, ultraviolet ray absorption property, rework property, step followability, adhesive force and holding power.

As a result of diligent studies to solve the above problems, the present inventors have a structural unit in which the glass transition temperature when homopolymerized is derived from a monomer in a specific range, and has a hydroxy group and an amide group. Alternatively, a copolymer having a specific range of contents of a unit having either an amino group and a unit having an acidic group and having a predetermined molecular weight, a cross-linking agent, and an ultraviolet absorber liquid or oily at 23 ° C. To complete the present invention, they have found that by obtaining an adhesive composition containing the above, it is possible to form an adhesive layer having good metal corrosion resistance, ultraviolet absorption, reworkability, step followability, adhesive strength and holding power. I arrived.

Specifically, the configurations of the present invention and preferred embodiments of the present invention are as follows.
[1] A pressure-sensitive adhesive composition containing a copolymer of a non-crosslinkable monomer and a crosslinkable monomer having a functional group, a cross-linking agent, and an ultraviolet absorber.
The copolymer contains a unit derived from a monomer having a glass transition temperature of more than -60 ° C and -20 ° C or less when made into a homopolymer as a unit composed of a non-crosslinkable monomer.
The content of a unit composed of a non-crosslinkable monomer in a copolymer and derived from a monomer having a glass transition temperature of 0 ° C. or higher when homopolymerized is based on the total mass of the copolymer. 10% by mass or less,
The copolymer contains a unit derived from a crosslinkable monomer whose functional group is either a hydroxy group, an amide group or an amino group as a unit composed of the crosslinkable monomer.
The content of the unit derived from the crosslinkable monomer whose functional group is either a hydroxy group, an amide group or an amino group in the copolymer is 20 to 60% by mass based on the total mass of the copolymer.
The content of the unit derived from the monomer having an acidic group among the units constituting the copolymer is less than 0.5% by mass with respect to the total mass of the copolymer.
The weight average molecular weight of the copolymer is 200,000 or more and 650,000 or less.
A pressure-sensitive adhesive composition in which the UV absorber is liquid or oily at 23 ° C.
[2] The pressure-sensitive adhesive composition according to [1], wherein the content of the unit derived from the monomer having a glass transition temperature of more than -60 ° C and -20 ° C is 40% by mass or more with respect to the total mass of the copolymer. Stuff.
[3] The crosslinkable monomer in which the functional group is either a hydroxy group, an amide group or an amino group is 2-hydroxyethyl (meth) acrylate or 4-hydroxybutyl (meth) acrylate, [1] or [2]. ] The pressure-sensitive adhesive composition according to.
[4] The pressure-sensitive adhesive composition according to any one of [1] to [3], wherein the functional group is a hydroxy group.
[5] The pressure-sensitive adhesive composition according to any one of [1] to [4], wherein the cross-linking agent is one or more selected from a bifunctional or higher epoxy compound and a bifunctional or higher isocyanate compound. Stuff.
[6] The pressure-sensitive adhesive composition according to any one of [1] to [5], wherein the ultraviolet absorber is a compound having a hydroxy group.
[7] The pressure-sensitive adhesive composition according to any one of [1] to [6], which contains 0.1 to 8 parts by mass of an ultraviolet absorber with respect to 100 parts by mass of the copolymer.
[8] The pressure-sensitive adhesive composition according to any one of [1] to [7], which further contains an antioxidant.
[9] The pressure-sensitive adhesive composition according to [8], wherein the antioxidant comprises a hindered phenol-based antioxidant and a phosphorus-based antioxidant.
[10] The pressure-sensitive adhesive composition according to any one of [1] to [9], wherein the ultraviolet absorber contains two or more types of ultraviolet absorbers having different maximum absorption wavelengths.
[11] Having an adhesive layer,
A pressure-sensitive adhesive sheet in which the pressure-sensitive adhesive layer is a cured product of the pressure-sensitive adhesive composition according to any one of [1] to [10].
[12] A first release sheet is provided on one surface of the pressure-sensitive adhesive layer.
A second release sheet is provided on the other surface of the pressure-sensitive adhesive layer.
The adhesive sheet according to [11], wherein the first release sheet and the second release sheet have different release forces.
[13] A laminate having an adherend on at least one surface of the pressure-sensitive adhesive sheet according to [11].
[14] The laminate according to [13], which has a metal or a metal oxide on the surface of any layer of the laminate.

According to the present invention, it is possible to provide a pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive layer having good metal corrosion prevention property, ultraviolet ray absorption property, rework property, step followability, adhesive force and holding power.

FIG. 1 is a cross-sectional view showing an example of the configuration of the pressure-sensitive adhesive sheet of the present invention. FIG. 2 is a cross-sectional view showing an example of the configuration of the laminated body of the present invention.

Hereinafter, the present invention will be described in detail. The description of the constituent elements described below may be based on typical embodiments or specific examples, but the present invention is not limited to such embodiments. The numerical range represented by using "-" in the present specification means a range including the numerical values before and after "-" as the lower limit value and the upper limit value.
In addition, "(meth) acrylic" is a general term for acrylic and methacrylic.

[Adhesive composition]
The pressure-sensitive adhesive composition of the present invention is a pressure-sensitive adhesive composition containing a copolymer of a non-crosslinkable monomer and a crosslinkable monomer having a functional group, a crosslinking agent, and an ultraviolet absorber.
Here, the copolymer contains, as a unit composed of a non-crosslinkable monomer, a unit derived from a monomer having a glass transition temperature of more than −60 ° C. and −20 ° C. or less when homopolymerized. The content of the unit composed of the non-crosslinkable monomer in the copolymer and derived from the monomer having a glass transition temperature of 0 ° C. or higher when homopolymerized is the total mass of the copolymer. On the other hand, it is 10% by mass or less. Further, the copolymer includes a unit derived from a crosslinkable monomer whose functional group is any of a hydroxy group, an amide group or an amino group as a unit composed of the crosslinkable monomer. The content of the unit derived from the crosslinkable monomer whose functional group is any of a hydroxy group, an amide group or an amino group in the copolymer is 20 to 60% by mass based on the total mass of the copolymer. Further, the content of the unit derived from the monomer having an acidic group among the units constituting the copolymer is less than 0.5% by mass with respect to the total mass of the copolymer, and the weight average molecular weight of the copolymer. Is 200,000 or more and 650,000 or less. The ultraviolet absorber contained in the pressure-sensitive adhesive composition is liquid or oily at 23 ° C.

With the above configuration, the pressure-sensitive adhesive composition of the present invention can form a pressure-sensitive adhesive layer having good metal corrosion resistance, ultraviolet absorption, reworkability, step followability, adhesive strength and holding power.
Specifically, by controlling the content of the unit derived from the monomer having an acidic group among the units constituting the copolymer in a very small range, the metal corrosion prevention property of the pressure-sensitive adhesive layer can be improved. Further, by controlling the content of the unit derived from the crosslinkable monomer, which is either a hydroxy group, an amide group or an amino group, among the crosslinkable monomer units constituting the copolymer in a range to be large to some extent, the copolymer can be used together with the crosslinker. The cross-linking probability of the polymer can be increased, and the holding power of the pressure-sensitive adhesive layer can be improved even when an ultraviolet absorber that is liquid or oily at 23 ° C. is used. The crosslinkable monomer, which is either a hydroxy group, an amide group, or an amino group, serves as a reaction point when a crosslinking agent is used, and the adhesive strength and holding power can be controlled by crosslinking.
In the present invention, by using a copolymer in which the glass transition temperature of the non-crosslinkable monomer is controlled in a specific range in combination with an ultraviolet absorber that is liquid or oily at 23 ° C., in addition to ultraviolet absorption, adhesion is achieved. The force and reworkability (balance between the two) can be improved. Reworkability refers to the property that a part of the adhesive of the adhesive sheet does not remain on the adherend during peeling after application, and that the adhesive sheet does not break during the rework work.
Further, the content of the unit composed of the non-crosslinkable monomer in the copolymer and derived from the monomer having a glass transition temperature of 0 ° C. or higher when homopolymerized is set to 10% by mass or less. By setting the weight average molecular weight of the polymer within a predetermined range, the step followability of the pressure-sensitive adhesive sheet can be improved.
Hereinafter, preferred embodiments of the pressure-sensitive adhesive composition of the present invention will be described.

<Copolymer>
The copolymer used in the present invention contains a monomer-derived unit having a glass transition temperature of more than -60 ° C and -20 ° C or less when homopolymer is used as the non-crosslinkable monomer unit constituting the copolymer. Here, the content of a unit composed of a non-crosslinkable monomer in a copolymer and derived from a monomer having a glass transition temperature of 0 ° C. or higher when homopolymerized is the total mass of the copolymer. It is 10% by mass or less. Further, the copolymer includes a unit derived from a crosslinkable monomer whose functional group is any of a hydroxy group, an amide group or an amino group as a unit composed of the crosslinkable monomer. In the copolymer, the content of the unit derived from the crosslinkable monomer whose functional group is either a hydroxy group, an amide group or an amino group is 20 to 60% by mass based on the total mass of the copolymer. The content of the unit derived from the monomer having an acidic group among the units constituting the copolymer is less than 0.5% by mass with respect to the total mass of the copolymer.

The weight average molecular weight of the copolymer may be 200,000 or more, preferably 300,000 or more. The weight average molecular weight of the copolymer may be 650,000 or less, preferably 600,000 or less, and more preferably 550,000 or less. By setting the weight average molecular weight of the copolymer within the above range, it is possible to improve the step followability while ensuring sufficient reworkability. The weight average molecular weight of the copolymer is a value before cross-linking with a cross-linking agent. The weight average molecular weight is a value measured by gel permeation chromatography (GPC) and determined based on polystyrene.

In the present invention, the copolymer is preferably an acrylic copolymer, more preferably a crosslinkable acrylic copolymer. The copolymer has no other restrictions as long as it contains the above-mentioned structural unit under predetermined conditions, and a known copolymer can be used.

(Unit composed of non-crosslinkable monomer)
-Units derived from monomers whose glass transition temperature exceeds -60 ° C and -20 ° C or less-
The copolymer contains a monomer-derived unit having a glass transition temperature of more than -60 ° C and -20 ° C or less when it is homopolymerized as a unit composed of a non-crosslinkable monomer of the copolymer. That is, the copolymer contains a unit derived from a non-crosslinkable monomer having a glass transition temperature of more than -60 ° C and -20 ° C or less when homopolymerized.
Examples of the monomer having a glass transition temperature of more than -60 ° C and -20 ° C or less when made into a homopolymer include n-butyl acrylate (BA), ethyl acrylate (EA), isobutyl acrylate (IBA), and isooctyl acrylate (IOA). , Isononyl acrylate (INAA), lauryl acrylate (LA), phenoxyethyl acrylate (PHEA), methoxyethyl acrylate (2MEA), tridecyl methacrylate (TDMA) and the like. Two or more of these may be used in combination if necessary.
The content of the unit derived from the monomer having a glass transition temperature of more than -60 ° C and -20 ° C or less when homopolymerized is preferably 20% by mass or more based on the total mass of the copolymer. It is more preferably mass% or more, further preferably 35 mass% or more, and particularly preferably 40 mass% or more. Further, the content of the unit derived from the monomer having a glass transition temperature of more than -60 ° C and -20 ° C or less when homopolymerized is preferably 90% by mass or less with respect to the total mass of the copolymer. , 85% by mass or less, and even more preferably 80% by mass or less.

-Units derived from monomers with a glass transition temperature of -60 ° C or less-
The copolymer may contain a monomer-derived unit having a glass transition temperature of −60 ° C. or lower when homopolymerized as a unit composed of the non-crosslinkable monomer of the copolymer. That is, the copolymer may contain a unit derived from a non-crosslinkable monomer having a glass transition temperature of −60 ° C. or lower when homopolymerized.
Examples of the non-crosslinkable monomer having a glass transition temperature of -60 ° C. or lower when homopolymerized include 2-ethylhexyl acrylate (2EHA), 2- (2-ethoxyethoxy) ethyl acrylate, and lauryl methacrylate (LMA). be able to. Two or more of these may be used in combination if necessary.
Among the units constituting the copolymer, the content of the unit derived from the monomer having a glass transition temperature of −60 ° C. or lower when homopolymerized is 0 to 10% by mass with respect to the total mass of the copolymer. It is preferable, it is more preferably 0 to 5% by mass, and particularly preferably 0 to 3% by mass.

-Unit derived from a monomer with a glass transition temperature of 0 ° C or higher-
The copolymer may contain a monomer-derived unit having a glass transition temperature of more than −20 ° C. when homopolymerized as a unit composed of the non-crosslinkable monomer of the copolymer. That is, the copolymer may contain a unit derived from a non-crosslinkable monomer whose glass transition temperature when homopolymerized exceeds −20 ° C. However, the content of the unit derived from the monomer having a glass transition temperature of 0 ° C. or higher when homopolymerized may be 10% by mass or less and 8% by mass with respect to the total mass of the copolymer. Is more preferable, and it is more preferably 5% by mass or less, and further preferably 3% by mass or less. It is particularly preferable that the copolymer does not substantially contain a unit derived from a monomer having a glass transition temperature of 0 ° C. or higher when it is homopolymerized. In the present specification, the state in which the unit derived from the monomer having a glass transition temperature of 0 ° C. or higher when the copolymer is homopolymer is substantially not contained means that the content of the unit derived from the monomer with respect to the copolymer is It means a state of 0.1% by mass or less.

Examples of non-crosslinkable monomers having a glass transition temperature of 0 ° C. or higher when homopolymerized are methyl acrylate (MA), methyl methacrylate (MMA), acrylamide (AM), hydroxyethylacrylamide (HEAA), and dimethylacrylamide. (DMAA), diethylacrylamide (DEAA), acryloylmorpholin (ACMO) and the like can be mentioned.

Here, the glass transition temperature in the present specification is the glass transition temperature when each monomer is homopolymerized. As a specific glass transition temperature, literature values may be adopted, but after each monomer is made into a homopolymer having a weight average molecular weight of 10,000 or more, the glass transition temperature of the homopolymer is measured by DSC (differential scanning calorimetry). The value measured using the total) may be adopted.

(Unit derived from crosslinkable monomer)
In the present invention, the unit composed of the crosslinkable monomer of the copolymer includes a unit derived from the crosslinkable monomer whose functional group is either a hydroxy group, an amide group or an amino group. That is, the copolymer contains a unit derived from a crosslinkable monomer having either a hydroxy group, an amide group or an amino group.
The functional group may be any of a hydroxy group, an amide group or an amino group, but the functional group is preferably a hydroxy group.
In the present invention, in the copolymer, the content of the unit derived from the crosslinkable monomer whose functional group is either a hydroxy group, an amide group or an amino group is 20 to 60 mass by mass with respect to the total mass of the copolymer. %, Preferably 20 to 50% by mass, and particularly preferably 20 to 40% by mass.

-Unit derived from a monomer having a hydroxy group-
When the crosslinkable monomer is a monomer having a hydroxy group, the monomer having a hydroxy group includes 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and polyethylene glycol. (Meta) acrylate and the like can be mentioned. Two or more of these may be used in combination if necessary.
The crosslinkable monomer in which the functional group is any of a hydroxy group, an amide group or an amino group is preferably a crosslinkable monomer in which the functional group is a hydroxy group, and among them, 2-hydroxyethyl (meth) acrylate or 4-. More preferably, it is a hydroxybutyl (meth) acrylate.
The content of the unit derived from the monomer having a hydroxy group in the copolymer is preferably 20 to 60% by mass, more preferably 25 to 55% by mass, based on the total mass of the copolymer. , 30-45% by mass, more preferably. When the content of the unit derived from the monomer having a hydroxy group among the units constituting the copolymer is 60% by mass or less, the adhesive strength of the pressure-sensitive adhesive layer can be improved.

-Unit derived from a monomer having an amino group or an amide group-
The copolymer may have a unit derived from a monomer having an amide group or an amino group in addition to a unit derived from a monomer having a hydroxy group as a crosslinkable monomer.
Examples of the unit derived from the monomer having an amide group or an amino group include amino group-containing (meth) acrylics such as (meth) acrylamide, morpholylacrylamide, N-methylaminoethyl acrylate, and N-tert-butylaminoethyl acrylate. Examples include acid esters.
Of the units constituting the copolymer, the unit derived from the monomer having an amide group or the amino group is a unit derived from the monomer having a crosslinkable functional group, and thus can be used in the range of 20 to 60% by mass. Since the monomer having a crosslinkable functional group preferably contains a monomer having a hydroxy group, the actual content is preferably 0 to 20% by mass, more preferably 0 to 10% by mass. , 0 to 5% by mass is particularly preferable, and 0% by mass is more preferable.
The copolymer may contain a unit derived from a monomer having a functional group other than a hydroxy group, an amide group or an amino group as a unit derived from a crosslinkable monomer. Examples of the monomer having another functional group include an epoxy group-containing monomer such as glycidyl (meth) acrylate.

(Unit derived from a monomer having an acidic group)
Examples of the monomer having an acidic group include carboxy group-containing monomers such as (meth) acrylic acid, maleic acid, maleic anhydride, itaconic acid, fumaric acid, and fumaric anhydride.
The content of the unit derived from the monomer having an acidic group among the units constituting the copolymer shall be less than 0.5% by mass and less than 0.1% by mass with respect to the total mass of the copolymer. Is more preferable, less than 0.01% by mass is more preferable, and 0% by mass is particularly preferable.
The monomer having an acidic group may be a crosslinkable monomer.

(Physical properties of copolymer)
The glass transition temperature (Tg) of the copolymer is preferably −75 ° C. or higher and −15 ° C. or lower, more preferably −60 ° C. or higher and −18 ° C. or lower, and −55 ° C. or higher and −20 ° C. or lower. It is more preferable to have. By setting the glass transition temperature (Tg) of the copolymer within the above range, the cohesive force when the pressure-sensitive adhesive composition is used as the pressure-sensitive adhesive layer can be further enhanced. As a result, an adhesive layer having excellent durability and adhesive strength can be obtained.

As the copolymer, a commercially available one may be used, or one synthesized by a known method may be used. When a copolymer synthesized by a known method is used, for example, a solution polymerization method can be applied. Examples of the solution polymerization method include an ionic polymerization method and a radical polymerization method. Examples of the solvent used at that time include tetrahydrofuran, chloroform, ethyl acetate, toluene, hexane, acetone, methyl ethyl ketone and the like. Specific examples of the method other than the solution polymerization method include a massive polymerization method, a suspension polymerization method, and an emulsion polymerization method.

<Crosslinking agent>
The cross-linking agent is preferably a cross-linking agent that reacts with the copolymer by heat.
As the cross-linking agent, the reactivity with the functional group of the copolymer is considered from among known cross-linking agents such as isocyanate compounds, epoxy compounds, oxazoline compounds, aziridine compounds, metal chelate compounds, and butylated melamine compounds. Can be selected as appropriate. In the present invention, since the copolymer contains any of a hydroxy group, an amide group or an amino group, it is preferable to use an isocyanate compound or an epoxy compound from the viewpoint of easy cross-linking.
In the present invention, the cross-linking agent is preferably one or more selected from a bifunctional or higher epoxy compound and a bifunctional or higher isocyanate compound, and more preferably a bifunctional or higher isocyanate compound. preferable.

Examples of the isocyanate compound include tolylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate and the like.
Examples of the epoxy compound 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 di. Glycidyl ether, tetraglycidyl xylene diamine, 1,3-bis (N, N-diglycidyl aminomethyl) cyclohexane, trimethylolpropan polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitol polyglycidyl ether, etc. Can be mentioned.
As the cross-linking agent, a commercially available product can be used. Examples of commercially available products include xylylene diisocyanate compounds (Mitsui Chemicals, Inc., Takenate D-110N), xylene diisocyanate crosslinkers (Soken Kagaku Co., Ltd., TD-75), polyisocyanate crosslinkers (Nippon Polyurethane Industry Co., Ltd.). , Coronate L-55E) and the like.

(Content of cross-linking agent)
As the cross-linking agent, one type may be used alone or two or more types may be used in combination. The content of the cross-linking agent in the pressure-sensitive adhesive composition is appropriately selected according to the desired adhesive properties and the like, and is not particularly limited. For example, it can be 0.01 parts by mass or more and 5 parts by mass or less, and 0.03 parts by mass or more and 3 parts by mass or less with respect to 100 parts by mass of the copolymer.

<UV absorber>
The pressure-sensitive adhesive composition of the present invention comprises an ultraviolet absorber that is liquid or oily at 23 ° C.
The fact that the UV absorber is liquid or oily at 23 ° C means a state in which the UV absorber alone is fluid at 23 ° C without a diluting solvent.

The ultraviolet absorber is preferably an ultraviolet absorber having a maximum absorption wavelength at a wavelength of 340 nm or more. Further, the ultraviolet absorber preferably contains two or more kinds of ultraviolet absorbers having different maximum absorption wavelengths. For example, it is preferable to combine an ultraviolet absorber having a maximum absorption wavelength of 300 nm or more and less than 350 nm and an ultraviolet absorber having a maximum absorption wavelength of 350 nm or more and 400 nm or less.

In the present invention, it is preferable that the ultraviolet absorber is a compound having a hydroxy group from the viewpoint that the ultraviolet absorption can be improved even if the content of the ultraviolet absorber is small.
Examples of the skeleton of the ultraviolet absorber include benzotriazole-based compounds and benzophenone-based compounds.
The ultraviolet absorber is preferably a compound represented by the following general formula (1) or (2). Further, as the ultraviolet absorber, it is also preferable to use a mixture of the compound represented by the following general formula (1) and the compound represented by the following general formula (2).

In general formula (1),
R1: Hydrogen atom, halogen atom, alkoxy group having 1 to 4 carbon atoms, nitro group or cyano group R2: Hydrogen atom or alkyl group having 1 to 8 carbon atoms R3: Alkyl group structure.

In general formula (2),
R1, R2, R3: At least one or more is a hydroxyl group, an alkyl group structure or a halogen atom.

Above all, it is preferable to introduce an alkyl group having a large molecular weight into the aromatic ring of the basic skeleton from the viewpoint of improving compatibility.
The reason why the compound represented by the general formula (1) or (2) is preferable is, for example, a compound in which chlorine, which is an electron-attracting group, is bonded to an aromatic ring on the side forming the triazole ring, or methylene on the phenol ring side. In the case of dimerization with a group, the maximum absorption wavelength of ultraviolet rays is shifted to the long wavelength side, and the absorption in the near-ultraviolet region is further strengthened.

A commercially available product can be used as the ultraviolet absorber. Examples of commercially available products include BASF's tinubin 384-2 and tinubin 109 as compounds represented by the general formula (1), and BASF's tinubin as the compound represented by the general formula (2). 477 and the like can be mentioned.

(Content of UV absorber)
The present invention is also characterized in that the blending amount of the ultraviolet absorber in the pressure-sensitive adhesive composition can be increased. Conventionally, when a large amount of an ultraviolet absorber is added to a pressure-sensitive adhesive composition, it may be difficult to achieve a high composition due to precipitation of the ultraviolet absorber. On the other hand, when the composition of the pressure-sensitive adhesive composition and the type of the UV absorber are adjusted in order to increase the blending amount of the UV absorber, metal corrosiveness and sticky physical properties may not be compatible. Therefore, in the present invention, by setting the composition of the pressure-sensitive adhesive composition to a predetermined structure, the ultraviolet absorber can be highly blended, and the metal corrosiveness, adhesive strength, holding power, step filling property and foreign matter filling property can be obtained. It has made it possible to achieve both various performances such as.

The content of the ultraviolet absorber is not particularly limited, and varies depending on the thickness of the pressure-sensitive adhesive layer. For example, when the pressure-sensitive adhesive layer is 100 μm (about ± 50 μm), the UV absorber is copolymerized. It is preferably contained in an amount of 0.1 to 8 parts by mass, more preferably 0.5 to 6 parts by mass, and particularly preferably 1 to 4 parts by mass with respect to 100 parts by mass.
By setting the content of the ultraviolet absorber to be at least the lower limit of the above range, the ultraviolet absorption can be improved. By setting the content of the ultraviolet absorber to be equal to or less than the upper limit of the above range, compatibility and holding power can be improved.
Further, two or more kinds of ultraviolet absorbers may be used in combination, and if it is the above-mentioned ultraviolet absorber, the content ratio in that case can be arbitrarily selected within the above-mentioned blending amount.

<Solvent>
The pressure-sensitive adhesive composition may further contain a solvent. The solvent is used to improve the coating suitability of the pressure-sensitive adhesive composition.
Examples of such a solvent include hydrocarbons such as hexane, heptane, octane, toluene, xylene, ethylbenzene, cyclohexane and methylcyclohexane; halogenated hydrocarbons such as dichloromethane, trichloroethane, trichloroethylene, tetrachloroethylene and dichloropropane; methanol. , Ethanol, propanol, isopropyl alcohol, butanol, isobutyl alcohol, diacetone alcohol and other alcohols; ethers such as diethyl ether, diisopropyl ether, dioxane and tetrahydrofuran; acetone, methyl ethyl ketone, methyl isobutyl ketone, isophorone, cyclohexanone and other ketones. Esters such as methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, amyl acetate, ethyl butyrate; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, propylene glycol monoethyl Examples thereof include polyols such as ether and propylene glycol monomethyl ether acetate and derivatives thereof.

One type of solvent may be used alone, or two or more types may be used in combination. The content of the solvent in the pressure-sensitive adhesive composition is not particularly limited, but is preferably 25 parts by mass or more and 500 parts by mass or less, and 30 parts by mass or more and 400 parts by mass or less with respect to 100 parts by mass of the copolymer. Is more preferable.
The content of the solvent is preferably 10% by mass or more and 90% by mass or less, and more preferably 20% by mass or more and 80% by mass or less, based on the total mass of the pressure-sensitive adhesive composition.
The pressure-sensitive adhesive composition preferably has a solid content concentration of 20 to 60% by mass, more preferably 30 to 50% by mass in a state containing a solvent.

<Antioxidant>
The pressure-sensitive adhesive composition of the present invention preferably further contains an antioxidant. When the pressure-sensitive adhesive composition further contains an antioxidant, the ultraviolet absorption can be enhanced more effectively. That is, the antioxidant contributes to more effectively enduring the UV absorber for long-term use. Since it is presumed that the alteration of the UV absorber is caused by the radicals generated from the residue of the polymerization initiator used when polymerizing the copolymer, by capturing the radicals generated by the antioxidant. It is considered that the alteration of the ultraviolet absorber can be suppressed.

Antioxidants are generally classified into primary antioxidants called radical chain terminators and secondary antioxidants that act as peroxide decomposition agents. Examples of the primary antioxidant include hindered phenol-based antioxidants, amine-based antioxidants, and lactone-based antioxidants. In addition, examples of the secondary antioxidant include phosphorus-based antioxidants and sulfur-based antioxidants. Among them, as the antioxidant, it is preferable to use a primary antioxidant and a secondary antioxidant in combination, and it is particularly preferable to use a hindered phenolic antioxidant and a phosphorus antioxidant in combination.

The content of the antioxidant is preferably 0.01% by mass or more and 5% by mass or less, and more preferably 0.05% by mass or more and 3% by mass or less, based on the total mass of the pressure-sensitive adhesive composition. .. By setting the content of the antioxidant within the above range, the ultraviolet absorption durability can be enhanced more effectively.

<Additives used together>
Examples of the additive used in combination with the cross-linking agent and the ultraviolet absorber include a light stabilizer typified by a hindered amine compound in terms of lowering the transmittance of ultraviolet rays. The mechanism of action of the light stabilizer is different from the mechanism of the above-mentioned ultraviolet absorber, and it is presumed that the radical-capturing effect is generally the main stabilizing effect, centering on three types of HALS oxides.

The content of the additive to be used in combination is preferably 0.03 to 1.5 parts by mass, more preferably 0.05 to 1.0 parts by mass with respect to 100 parts by mass of the copolymer. If the content of the additive is above the lower limit, the UV absorption can be reliably maintained when used for a long time in a high temperature, low temperature and moist heat environment, and if it is below the upper limit, the transmittance at 380 nm. It is possible to prevent the rise and the decrease in adhesive strength.

In addition to the above-mentioned additives, the pressure-sensitive adhesive composition may contain other additives such as a pressure-sensitive adhesive, a silane coupling agent, and a metal corrosion inhibitor, if necessary.
Examples of the tackifier include rosin resin, terpene resin, terpene phenol resin, kumaron inden resin, styrene resin, xylene resin, phenol resin, petroleum resin and the like.
Examples of the silane coupling agent include a mercaptoalkoxysilane compound (for example, a mercapto group-substituted alkoxy oligomer).
As the metal corrosion inhibitor, a type that prevents corrosion by forming a complex with a metal and forming a film on the metal surface is preferable, and a benzotriazole-based metal corrosion inhibitor is particularly preferable.

[Adhesive sheet]
The pressure-sensitive adhesive sheet of the present invention has a pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer is a cured product of the pressure-sensitive adhesive composition of the present invention.

The pressure-sensitive adhesive sheet of the present invention has a pressure-sensitive adhesive layer. The pressure-sensitive adhesive sheet may be a single-layer pressure-sensitive adhesive sheet composed of only the pressure-sensitive adhesive layer. Further, the adhesive sheet of the present invention may be a single-sided adhesive sheet or a double-sided adhesive sheet.
Examples of the single-sided adhesive sheet include a multi-layer sheet in which an adhesive layer is laminated on a support. Further, another layer may be provided between the support and the pressure-sensitive adhesive layer.
The double-sided adhesive sheet includes a single-layer adhesive sheet composed of an adhesive layer, a multi-layer adhesive sheet in which a plurality of adhesive layers are laminated, and a multi-layer adhesive in which another adhesive layer is laminated between the adhesive layers. Examples thereof include a sheet and a multi-layered pressure-sensitive adhesive sheet in which a support is laminated between the pressure-sensitive adhesive layer and the pressure-sensitive adhesive layer. When the double-sided adhesive sheet has a support, it is preferable to use a transparent support as the support. Since such a double-sided pressure-sensitive adhesive sheet is also excellent in transparency of the pressure-sensitive adhesive sheet as a whole, it can be suitably used for bonding optical members to each other.
Among the above-mentioned adhesive sheets, the non-carrier type is preferable, and a single-layer adhesive sheet composed of an adhesive layer or a multi-layered adhesive sheet in which a plurality of adhesive layers are laminated is preferable, and a single layer composed of an adhesive layer is preferable. A double-sided adhesive sheet is particularly preferable.

When the pressure-sensitive adhesive sheet of the present invention has a support, the support includes, for example, plastics such as polystyrene, styrene-acrylic copolymer, acrylic resin, polyethylene terephthalate, polycarbonate, polyether ether ketone, and triacetyl cellulose. Films: Antireflection films, transparent conductive films such as ITO vapor deposition films and metal mesh films, optical films such as electromagnetic wave shielding films, and the like.

It is preferable that the surface of the adhesive layer is covered with a release sheet. That is, the adhesive sheet may be an adhesive sheet with a release sheet. FIG. 1 is a cross-sectional view showing an example of the configuration of an adhesive sheet with a release sheet. The adhesive sheet 11 shown in FIG. 1 has a release sheet (12a, 12b). The adhesive sheet 11 in FIG. 1 is a non-carrier type single-layer adhesive sheet and is a double-sided adhesive sheet.

The release sheet is a removable 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 polypropylene film as a low-polarity base material. Can be mentioned.
Papers and polymer films are used as the base material for the release sheet in the releaseable laminated sheet. As the release agent constituting the release agent layer, for example, a general-purpose addition type or condensation type silicone type release agent or a long-chain alkyl group-containing compound is used. In particular, an addition type silicone release agent having high reactivity is preferably used.
Specific examples of the silicone-based release agent 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. Can be mentioned. Further, it contains a silicone resin which is an organic silicon compound having an SiO ₂ units and _{(CH 3) 3 SiO 1/2} units or _{CH 2 = CH (CH 3)} SiO 1/2 units in the silicone-based release agent preferable. Specific examples of the silicone resin include BY24-843, SD-7292, SHR-1404, etc. manufactured by Toray Dow Corning Silicone Co., Ltd., KS-3800, X92-183, etc. manufactured by Shin-Etsu Chemical Co., Ltd.

In the present invention, one surface of the pressure-sensitive adhesive layer is provided with a first release sheet, and the other surface of the pressure-sensitive adhesive layer is provided with a second release sheet, and the release force of the first release sheet and the second release sheet. Is preferably different. In the example of FIG. 1, in the release sheet 12, it is preferable that the release sheet 12a and the release sheet 12b have different peelability in order to facilitate the release. That is, if the peelability from one side and the peelability from the other side are different, it becomes easy to peel off only the release sheet 12 having the higher peelability first. In that case, the peelability of the release sheet 12a and the release sheet 12b may be adjusted according to the bonding method and the bonding order.

The thickness of the pressure-sensitive adhesive layer can be appropriately set according to the application and is not particularly limited, but is usually preferably in the range of 20 μm or more and 500 μm or less, more preferably 30 μm or more and 450 μm or less, and 40 μm or more and 400 μm or less. It is more preferable that it is 50 μm or more and 300 μm or less. By setting the thickness of the pressure-sensitive adhesive layer within the above range, it is possible to sufficiently secure the step-following property and further improve the durability. Further, by setting the thickness of the pressure-sensitive adhesive layer within the above range, it becomes easy to manufacture a double-sided pressure-sensitive adhesive sheet. When the thickness of the pressure-sensitive adhesive layer is thin, it is preferable to add an ultraviolet absorber in an amount close to the upper limit.

In the present invention, it is preferable to control the spectral transmittance of the pressure-sensitive adhesive sheet with light having a wavelength of 380 nm to 5% or less regardless of the thickness of the pressure-sensitive adhesive layer.
It is empirically known that if the ultraviolet transmittance at 380 nm is 8% or less, no problem will occur in a flat panel display such as a mobile phone or a smartphone for a long period of time. However, the ultraviolet absorption used in the present invention is used. If the agent is blended in the above range, the spectral transmittance of the pressure-sensitive adhesive sheet with light having a wavelength of 380 nm can be controlled within the above range.

The adhesive strength of the pressure-sensitive adhesive layer is preferably 1N / 25mm or more, more preferably 5N / 25mm or more, and particularly preferably more than 8N / 25mm.

The adhesive strength of the adhesive layer to the adherend described above is a value measured by peeling 180 ° to each adherend and the adhesive strength is measured according to JIS Z0237.

(Manufacturing method of adhesive sheet)
The method for producing the adhesive sheet is not particularly limited.
The pressure-sensitive adhesive sheet of the present invention may be composed of a pressure-sensitive adhesive layer and another layer, but it is preferably composed of only the pressure-sensitive adhesive layer. Examples of the other layer include a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive composition other than the above, a support, a release sheet, and the like. Examples of the support include plastic films such as polystyrene, styrene-acrylic copolymer, acrylic resin, polyethylene terephthalate, polycarbonate, polyether ether ketone, and triacetyl cellulose; optical films such as antireflection film and electromagnetic wave shielding film; and the like. Can be mentioned.

The manufacturing process of the pressure-sensitive adhesive sheet preferably includes a step of applying the pressure-sensitive adhesive composition on the release sheet to form a coating film and a step of heating the coating film to form a cured product.

Hereinafter, a step of applying the pressure-sensitive adhesive composition on the release sheet to form a coating film and a step of heating the coating film to form a cured product will be described as a representative.

The coating of the pressure-sensitive adhesive composition forming the pressure-sensitive adhesive sheet can be carried out using a known coating device. Examples of the coating apparatus include a blade coater, an air knife coater, a roll coater, a bar coater, a gravure coater, a micro gravure coater, a rod blade coater, a lip coater, a die coater, a curtain coater and the like.

The coating film can be heated using a known heating device such as a heating furnace or an infrared lamp. By heating the coating film, the reaction between the copolymer and the cross-linking agent proceeds to form a cured product (adhesive sheet). In order to bring the pressure-sensitive adhesive composition into a cured state, an aging treatment may be performed in which the pressure-sensitive adhesive sheet is allowed to stand at a constant temperature for a certain period of time after the solvent is removed after coating. The aging treatment can be performed, for example, by allowing it to stand at 23 ° C. for 7 days.

(How to use the adhesive sheet)
In the method of using the pressure-sensitive adhesive sheet of the present invention, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is brought into contact with the surface of the adherend.

[Laminate]
The laminate of the present invention is a laminate having an adherend on at least one surface of the pressure-sensitive adhesive sheet of the present invention.
The adherend may have a metal or metal oxide on its surface. Further, the surface of any layer of the laminate may have a metal or a metal oxide.

In the laminated body of the present invention, the adherend may have a stepped portion. Further, the adherend is preferably an optical member constituting an image display device having a liquid crystal module or an optical member constituting a touch panel. The laminate is preferably obtained through a step of bringing the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet into contact with the surface of the adherend.

FIG. 2 is a cross-sectional view showing an example of the configuration of the laminated body 20 in which the adhesive sheet 21 of the present invention is bonded to the adherend 22 and the adherend 24. As shown in FIG. 2, the adherends 22 and 24 have a stepped portion (only one side of 27a, 27b, 27c, 27d or 27a and 27b or 27c and 27d may be used). In FIG. 2, the adherend 22 has a stepped portion (27a, 27b), and the adherend 24 has a stepped portion (27c, 27d). The thickness of the stepped portion (27a, 27b, 27c, 27d) is usually 5 μm or more and 60 μm or less. As described above, the pressure-sensitive adhesive sheet 21 of the present invention is preferably capable of being bonded to a member having a stepped portion, and preferably can follow the unevenness of the stepped portion.

The adherend is preferably an optical member. Examples of the optical member include each component in an optical product such as a touch panel and an image display device.
Examples of the 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, and a transparent conductive film in which a transparent resin film is coated with a conductive polymer. Examples include hard coat films and fingerprint resistant films. The adhesive sheet of the present invention is preferably for stacking touch panel sensors, and more preferably for stacking touch panel sensors using a touch pen. From this point of view, the adherend of the pressure-sensitive adhesive sheet of the present invention includes 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, and a conductive polymer on a transparent resin film. A transparent conductive film coated with is preferable.
Examples of the constituent members of the image display device include antireflection films, alignment films, polarizing films, retardation films, and luminance improving films used in liquid crystal display devices.
Examples of the material used for these members include glass, polycarbonate, polyethylene terephthalate, polymethylmethacrylate, polyethylene naphthalate, cycloolefin polymer, triacetyl cellulose, polyimide, cellulose acylate and the like.

When the adhesive sheet of the present invention is a double-sided adhesive sheet, it can be used for bonding two adherends. In this case, the adhesive sheet of the present invention is used to bond ITO films to each other inside a touch panel, to bond an ITO film to an ITO glass, to bond an ITO film to a liquid crystal panel on a touch panel, and to bond a cover glass to an ITO film. It is used for bonding and bonding of cover glass and decorative film.

(Manufacturing method of laminated body)
The present invention also relates to a method for producing a laminate. The method for producing the laminate preferably includes a step of bringing the above-mentioned pressure-sensitive adhesive sheet into contact with the surface of the adherend.

The features of the present invention will be described in more detail below with reference to Examples and Comparative Examples. The materials, amounts used, ratios, treatment contents, treatment procedures, etc. shown in the following examples can be appropriately changed as long as they do not deviate from the gist of the present invention. Therefore, the scope of the present invention should not be construed as limiting by the specific examples shown below.

[Example 1]
<Preparation of adhesive composition>
80% by mass of n-butyl acrylate (BA; Tg is about -55 ° C) as a non-crosslinkable monomer having a glass transition temperature of more than -60 ° C and -20 ° C or less, and 2-hydroxyethyl acrylate (2HEA) as a hydroxy group-containing monomer. ) Was blended so as to be 20% by mass. Next, with respect to 100 parts by mass of butyl acrylate and 2-hydroxyethyl acrylate, 20 parts by mass of ethyl acetate as an organic solvent for polymerization and 2,2'-azobis (2,4-dimethylvaleronitrile) as a radical polymerization initiator were 0. It was dissolved in a 0.01 part by mass solution. The solution was heated to 60 ° C. and random copolymerized to obtain a copolymer (A). The weight average molecular weight of the copolymer (A) was 450,000.
The weight average molecular weight is a value measured by gel permeation chromatography (GPC) and determined based on polystyrene.
The measurement conditions for gel permeation chromatography (GPC) are as follows.
Solvent: Tetrahydrofuran Column: Shodex KF801, KF803L, KF800L, KF800D (4 units manufactured by Showa Denko KK were connected and used)
Column temperature: 40 ° C
Sample concentration: 0.5% by mass
Detector: RI-2031plus (manufactured by JASCO)
Pump: RI-2080plus (manufactured by JASCO)
Flow rate (flow velocity): 0.8 ml / min Injection amount: 10 μl
Calibration curve: Standard polystyrene Shodex standard polystyrene (manufactured by Showa Denko KK) A calibration curve of 10 samples from Mw = 1320 to 2,500,000 was used.
0.11 part by mass of xylylene diisocyanate compound (Takenate D-110N, manufactured by Mitsui Chemicals, Inc.) as a cross-linking agent with respect to 100 parts by mass of the solid content of the copolymer (A) obtained above, absorbs ultraviolet rays. Add 1.13 parts by mass of the agent (Chinubin 477 manufactured by BASF) and 1.18 parts by mass of another ultraviolet absorber (Chinubin 384-2 manufactured by BASF) so that the solid content concentration becomes 40% by mass. Ethyl acetate was added to the pressure-sensitive adhesive composition.
BASF's tinubin 477 used as an ultraviolet absorber is a hydroxy group-containing triazine compound, and tinuvin 384-2 is a hydroxy group-containing benzotriazole compound, both of which are oily at 23 ° C. It was.

<Making an adhesive sheet>
A 38 μm-thick polyethylene terephthalate film (first release sheet) (manufactured by Oji F-Tex Co., Ltd .: 38RL-07) having a release agent layer treated with a silicone-based release agent on the pressure-sensitive adhesive composition prepared as described above. The surface of (2)) was uniformly coated with an applicator so that the coating amount after drying was 150 μm / m ² . Then, it was dried in the air circulation type constant temperature oven of 100 degreeC for 3 minutes, and the pressure-sensitive adhesive layer was formed on the surface of the first release sheet. Next, a second release sheet (manufactured by Oji F-Tex Co., Ltd .: 38RL-07 (L)) having a thickness of 38 μm is attached to the surface of the pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer is paired with a difference in peeling power. An adhesive sheet having a structure of a first release sheet / an adhesive layer / a second release sheet sandwiched between the release sheets was obtained. The adhesive sheet was subjected to an aging treatment in which it was allowed to stand for 7 days at 23 ° C. and 50% relative humidity.

[Examples 2 and 3]
Instead of the copolymer (A) synthesized in Example 1, the content of the non-crosslinkable monomer and the hydroxy group-containing monomer used in the synthesis of the copolymer was changed as shown in Table 1 below. A pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet were obtained in the same manner as in Example 1 except that the polymer was used.

[Example 4]
0.1 part by mass of hindered phenol-based antioxidant (Irganox 1010 manufactured by BASF) and phosphorus-based antioxidant (Irgafos 168 manufactured by BASF) 0 with respect to 100 parts by mass of the copolymer (A). A pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet were obtained in the same manner as in Example 1 except that 1 part by mass was added.

[Example 5]
0.1 parts by mass of hindered phenol-based antioxidant (Irganox 1010 manufactured by BASF) and 0.1 parts by mass of phosphorus-based antioxidant (Irgafos 168 manufactured by BASF) with respect to 100 parts by mass of the copolymer. A pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet were obtained in the same manner as in Example 2 except that the portion was added.

[Example 6]
0.1 parts by mass of hindered phenol-based antioxidant (Irganox 1010 manufactured by BASF) and 0.1 parts by mass of phosphorus-based antioxidant (Irgafos 168 manufactured by BASF) with respect to 100 parts by mass of the copolymer. A pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet were obtained in the same manner as in Example 3 except that the portion was added.

[Example 7]
Instead of the copolymer (A) synthesized in Example 1, a copolymer synthesized by changing the mass ratio content of the monomer used for synthesizing the copolymer as shown in Table 1 below was used. Obtained a pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet in the same manner as in Example 1.

[Example 8]
With respect to 100 parts by mass of butyl acrylate and 2-hydroxyethyl acrylate, 25 parts by mass of ethyl acetate as an organic solvent for polymerization and 2,2'-azobis (2,4-dimethylvaleronitrile) as a radical polymerization initiator were 0. A copolymer (B) was obtained in the same manner as in Example 1 except that the weight was changed to 02 parts by mass. The weight average molecular weight of the copolymer (B) was 350,000.
A pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet were obtained in the same manner as in Example 5 except that the copolymer (B) was used instead of the copolymer (A).

[Comparative Example 1]
The pressure-sensitive adhesive composition of Comparative Example 1 was prepared by the following method with reference to Example 1 of JP2012-014043A.
Instead of the copolymer A synthesized in Example 1, the copolymer (C) synthesized by changing the content of the monomer used for the synthesis of the copolymer as shown in Table 1 below was used to absorb ultraviolet rays. A pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet were obtained in the same manner as in Example 1 except that the agent was changed as shown in Table 1 below.
In Comparative Example 1, BA was 65% by mass, methyl acrylate (MA) was 35% by mass as a non-crosslinkable monomer at −20 ° C. <Tg, and acrylic acid (AA) was 2% by mass as an acidic group-containing monomer. , MA and AA were blended in a mass ratio of 65:35: 2, and a copolymer (C) was obtained in the same manner as in Example 1. The weight average molecular weight of the copolymer (C) was 450,000.
In Comparative Example 1, 2 parts by mass of Chinubin 144 manufactured by BASF and 4 parts by mass of Chinubin 109 manufactured by BASF were used as the ultraviolet absorber. BASF's Tinubin 144 used as an ultraviolet absorber was a pale yellow powder, and Tinubin 109 was oily at 23 ° C.

[Comparative Example 2]
The pressure-sensitive adhesive composition of Comparative Example 2 was prepared by the following method with reference to Example 1 of JP-A-2014-196377.
Instead of the copolymer A synthesized in Example 1, the copolymer (D) synthesized by changing the content of the monomer used for the synthesis of the copolymer as shown in Table 1 below was used as a cross-linking agent. A pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet were obtained in the same manner as in Example 1 except that the ultraviolet absorber was changed as shown in Table 1 below, using "Coronate L-55E" manufactured by Nippon Polyurethane Co., Ltd.
In Comparative Example 2, BA, MA and 2HEA were blended so that BA was 39% by mass, MA was 60% by mass and 2HEA was 1% by mass, and 2,2'-azobis (2) as a radical polymerization initiator. , 4-Dimethylvaleronitrile) was used in place of 2,2'-azobisisobutyronitrile), and a copolymer (D) was obtained in the same manner as in Example 1. The weight average molecular weight of the copolymer (D) was 450,000.
In Comparative Example 2, 4 parts by mass of Tinubin 477 manufactured by BASF was used as an ultraviolet absorber.

[Comparative Example 3]
The pressure-sensitive adhesive composition of Comparative Example 3 was prepared by the following method with reference to Example 1 of JP2012-207055A.
Instead of the copolymer A synthesized in Example 1, the copolymer (E) synthesized by changing the content of the monomer used for the synthesis of the copolymer as shown in Table 1 below was used, and a cross-linking agent was used. A xylene diisocyanate-based cross-linking agent (TD-75 manufactured by Soken Kagaku Co., Ltd.) was used as a pressure-sensitive adhesive in the same manner as in Example 1 except that the ultraviolet absorber was changed as shown in Table 1 below. The composition and the pressure-sensitive adhesive sheet were obtained.
In Comparative Example 3, using 2- (dimethylamino) ethyl acrylate (DMAEA; Tg about -60 ° C.), BA, MA and 2HEA, DMAEA was 0.5% by mass, BA was 66.5% by mass, and MA was used. A copolymer (E) was obtained in the same manner as in Example 1 except that 30% by mass and 2HEA were blended so as to be 3% by mass. The weight average molecular weight of the copolymer (E) was 450,000.
In Comparative Example 3, 4 parts by mass of an ultraviolet absorber composed of ethyl-2-cyano-3,3-diphenylacrylate (SEESORB 501 manufactured by Dipro Chemical Co., Ltd .; which does not contain a hydroxy group) was used as the ultraviolet absorber. SEESORB 501 manufactured by Zipuro Kasha was solid at 23 ° C.

[Comparative Example 4]
Instead of the copolymer (A) synthesized in Example 1, a copolymer synthesized by changing the mass ratio content of the monomer used for synthesizing the copolymer as shown in Table 1 below was used. Obtained a pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet in the same manner as in Example 1.

[Comparative Example 5]
With respect to 100 parts by mass of butyl acrylate and 2-hydroxyethyl acrylate, 10 parts by mass of ethyl acetate as an organic solvent for polymerization and 2,2'-azobis (2,4-dimethylvaleronitrile) as a radical polymerization initiator were 0. A copolymer (F) was obtained in the same manner as in Example 1 except that the amount was changed to 01 parts by mass. The weight average molecular weight of the copolymer (F) was 1 million.
A pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet were obtained in the same manner as in Example 5 except that the copolymer (F) was used instead of the copolymer (A).

[Comparative Example 6]
With respect to 100 parts by mass of butyl acrylate and 2-hydroxyethyl acrylate, 30 parts by mass of ethyl acetate as an organic solvent for polymerization and 2,2'-azobis (2,4-dimethylvaleronitrile) as a radical polymerization initiator were 0. A copolymer (G) was obtained in the same manner as in Example 1 except that it was changed to 04 parts by mass. The weight average molecular weight of the copolymer (G) was 150,000.
A pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet were obtained in the same manner as in Example 5 except that the copolymer (G) was used instead of the copolymer (A).

[Evaluation]
<Metal corrosion prevention>
The adhesive sheet is cut to a size of 5 mm x 12 mm, one of the release sheets is peeled off, a PET film with a thickness of 100 μm (product name: Cosmo Shine A4300, manufactured by Toyobo Co., Ltd.) is attached, and the transparent film is used as the base material. Obtained an adhesive sheet. Next, the other release sheet was peeled off, the pressure-sensitive adhesive layer side was bonded to a copper plate, and then stored in an atmosphere of 85 ° C. and a relative humidity of 85% for 240 hours. Then, the surface of the copper foil was visually observed from the transparent PET film side to confirm the presence or absence of corrosion on the surface of the copper plate, and the evaluation was performed according to the following evaluation criteria.
(Evaluation criteria)
◯: No corrosion is observed.
X: Corrosion is observed.

<UV absorption>
An adhesive sheet based on a transparent film is cut into 50 mm × 50 mm, and the light release sheet is peeled off to form a transparent film and an adhesive layer, and then an ultraviolet-visible near-infrared spectrophotometer (model: UV-3100PC, The spectral transmittance at a wavelength of 380 nm was measured using (manufactured by Shimadzu Corporation).
Evaluation was made according to the following evaluation criteria.
(Evaluation criteria)
◯: Transmittance is less than 8%.
X: Transmittance is 8% or more.

<ITO corrosiveness>
The surface electrical resistance value of the ITO layer of the glass substrate with the ITO layer was measured using a digital multimeter (CUSTOM Co., Ltd., CDM-2000D). Next, the lightly peeling sheet of the adhesive sheet obtained in each Example and Comparative Example was peeled off and attached to a PET substrate, and cut so that the sample size was 20 mm × 70 mm. Next, a silver paste was applied to the ITO vapor deposition layer of ITO glass so that the interval was 65 mm, and the mixture was dried. Then, the adhesive sheets were attached so as to bridge the silver paste, and the mixture was left in an oven at a temperature of 60 ° C. and a relative humidity of 90% for 240 hours. Then, after taking out and returning to room temperature, the electric resistance value was measured through the silver paste. The resistance change rate before and after the test was calculated by the following formula and evaluated according to the following criteria.
Resistance change rate (%) = [(Post-test surface resistance value)-(Pre-test surface resistance value)] / [Pre-test surface resistance value]
⊚: The rate of change in resistance is less than 25%.
◯: The resistance change rate is 25% or more and less than 50%.
X: The resistance change rate is 50% or more.

<Compatibility (recrystallization)>
An adhesive sheet using a transparent PET film as a base material was cut into 50 mm × 50 mm, treated in an environment of −40 ° C. for 250 hours, and visually inspected for recrystallization of an ultraviolet absorber. Those in which the UV absorber was not recrystallized were marked with ◯, and those in which the UV absorber was recrystallized and localized were marked with x.

<Reworkability>
A double-sided adhesive sheet (adhesive sheet having a structure of a light release sheet / an adhesive layer / a heavy release sheet) was cut out to a size of 5 cm × 5 cm, and the release film on the light release side was peeled off and bonded to soda glass. Then, it was treated with an autoclave at 0.5 MPa and 40 ° C. for 30 minutes to remove the release film on the heavy release side. Then, the double-sided adhesive sheet was reworked (peeled from the glass) by hand peeling. The reworkability of the double-sided adhesive sheet at that time was evaluated according to the following criteria.
⊚: The double-sided adhesive sheet is easily and neatly peeled off from the glass, leaving no adhesive.
◯: The double-sided adhesive sheet is easily peeled off from the glass, and the adhesive remains on the edge in a line, but it can be easily removed by hand.
Δ: The double-sided adhesive sheet peels off from the glass, but the adhesive sheet breaks in the middle and is difficult to peel off.
X: The double-sided adhesive sheet is cut off immediately, and the double-sided adhesive sheet does not come off from the glass.

<Step property>
<Preparation of laminated body (1)>
Ultraviolet curable ink was applied to the surface of a glass plate (length 90 mm × width 50 mm × thickness 0.5 mm) and screen-printed in a frame shape (length 90 mm × width 50 mm, width 5 mm) so that the coating thickness was 5 μm. Next, the ultraviolet curable ink printed by irradiating with ultraviolet rays was cured. This step was repeated three times to obtain a printed stepped glass having a stepped portion of 15 μm.
The obtained adhesive sheet is cut into a shape of 90 mm in length × 50 mm in width, the first release sheet is peeled off, and the adhesive layer is printed on a stepped glass using a laminator (manufactured by Yubon Co., Ltd., IKO-650EMT). It was pasted so as to cover the entire surface of the frame-shaped print. Then, the second release sheet was peeled off, and a glass plate (length 90 mm × width 50 mm × thickness 0.5 mm) was attached to the surface of the exposed pressure-sensitive adhesive layer with the above laminator, and autoclaved (40 ° C., 0. 5 MPa, 30 minutes) was carried out to obtain a laminated body (1). The printed step portion of the laminated body (1) was observed with a microscope (magnification: 25 times), and the step followability of the adhesive sheet was evaluated according to the following criteria.
⊚: The step is completely filled.
◯: Air remains in a part of the stepped portion.
X: Air remains in the entire step portion.

<Adhesive strength>
An adhesive sheet using a transparent PET film as a base material was cut into 25 mm × 60 mm, the light release sheet was peeled off, the glass plate was pressure-bonded with a 2 kg load roll, and the mixture was left at room temperature for 30 minutes. After that, using a tensile tester (model: Autograph AGS-J, manufactured by Shimadzu Corporation), the peel strength when peeled 180 degrees at a tensile speed of 300 mm / min was measured according to JIS Z 0237, and the peel strength was measured. Adhesive strength.
Those having an adhesive strength of more than 8N / 25mm were marked with ⊚, those with an adhesive strength of 5 to 8N / 25mm were marked with ◯, those with an adhesive strength of 1N / 25mm or more and less than 5N / 25mm were marked with Δ, and those with an adhesive strength of less than 1N / 25mm were marked with x.

<Holding power>
The holding force of the adhesive sheet was measured according to JIS Z 0237 by the following procedure.
The light release sheet of the adhesive sheet manufactured above is peeled off, a PET film (Cosmo Shine A4300 100 μm manufactured by Toyobo Co., Ltd.) is attached to the exposed adhesive, and then cut into a size of 225 mm × 50 mm and the heavy release sheet is peeled off. The exposed adhesive layer was attached so that the contact surface with the surface of the SUS plate was 25 mm × 25 mm. Then, a 1 kg weight was attached to the adhesive sheet protruding from the SUS plate, and the weight was left for 24 hours in a 40 ° C. dry environment. After taking out, the distance between the adhesive sheet and the SUS plate interface was measured.
Evaluation was made according to the following evaluation criteria.
(Evaluation criteria)
○ ・ ・ ・ The deviation distance is less than 5 mm.
×: The deviation distance is 5 mm or more, or the weight falls.

From Tables 1 and 2 above, it was found that the pressure-sensitive adhesive compositions obtained in Examples 1 to 8 can have good metal corrosion prevention property, ultraviolet ray absorption property, step followability, rework property, adhesive force and holding power. .. Further, the adhesive sheets obtained in Examples 1 to 8 were also excellent in step followability, and in particular, the adhesive sheets obtained in Examples 1 to 6 and 8 were excellent in step followability. Further, in Examples 4 to 8, adhesive sheets having excellent ITO corrosiveness were obtained.
On the other hand, in the adhesive sheet obtained in the comparative example, all the conditions of metal corrosion prevention property, ultraviolet ray absorption property, step followability, rework property, adhesive force and holding power were not satisfied.

1 Adhesive sheet with release sheet 11 Adhesive sheet (adhesive layer)
12a, 12b Release sheet 20 Laminated body 21 Adhesive sheet (adhesive layer)
22 Adhesive body 24 Adhesive body 27a, 27b, 27c, 27d Step

Claims (14)

1. A pressure-sensitive adhesive composition containing a copolymer of a non-crosslinkable monomer and a crosslinkable monomer having a functional group, a cross-linking agent, and an ultraviolet absorber.
   The copolymer contains a unit derived from a monomer having a glass transition temperature of more than -60 ° C and -20 ° C or less when made into a homopolymer as a unit composed of the non-crosslinkable monomer.
   The content of the unit composed of the non-crosslinkable monomer in the copolymer and derived from the monomer having a glass transition temperature of 0 ° C. or higher when homopolymerized is the total mass of the copolymer. 10% by mass or less,
   The copolymer contains a unit derived from a crosslinkable monomer having a functional group of either a hydroxy group, an amide group or an amino group as a unit composed of the crosslinkable monomer.
   The content of the unit derived from the crosslinkable monomer whose functional group is any of a hydroxy group, an amide group or an amino group in the copolymer is 20 to 60% by mass based on the total mass of the copolymer. Yes,
   The content of the unit derived from the monomer having an acidic group among the units constituting the copolymer is less than 0.5% by mass with respect to the total mass of the copolymer.
   The weight average molecular weight of the copolymer is 200,000 or more and 650,000 or less.
   A pressure-sensitive adhesive composition in which the UV absorber is liquid or oily at 23 ° C.
2. The pressure-sensitive adhesive composition according to claim 1, wherein the content of the unit derived from the monomer having a glass transition temperature of more than -60 ° C and -20 ° C is 40% by mass or more with respect to the total mass of the copolymer. Stuff.
3. The first or second claim, wherein the crosslinkable monomer in which the functional group is any of a hydroxy group, an amide group or an amino group is 2-hydroxyethyl (meth) acrylate or 4-hydroxybutyl (meth) acrylate. Adhesive composition.
4. The pressure-sensitive adhesive composition according to any one of claims 1 to 3, wherein the functional group is a hydroxy group.
5. The pressure-sensitive adhesive composition according to any one of claims 1 to 4, wherein the cross-linking agent is one type or two or more types selected from a bifunctional or higher functional epoxy compound and a bifunctional or higher functional isocyanate compound.
6. The pressure-sensitive adhesive composition according to any one of claims 1 to 5, wherein the ultraviolet absorber is a compound having a hydroxy group.
7. The pressure-sensitive adhesive composition according to any one of claims 1 to 6, which contains 0.1 to 8 parts by mass of the ultraviolet absorber with respect to 100 parts by mass of the copolymer.
8. The pressure-sensitive adhesive composition according to any one of claims 1 to 7, further containing an antioxidant.
9. The pressure-sensitive adhesive composition according to claim 8, wherein the antioxidant comprises a hindered phenol-based antioxidant and a phosphorus-based antioxidant.
10. The pressure-sensitive adhesive composition according to any one of claims 1 to 9, wherein the ultraviolet absorber contains two or more types of ultraviolet absorbers having different maximum absorption wavelengths.
11. Has an adhesive layer,
    A pressure-sensitive adhesive sheet, wherein the pressure-sensitive adhesive layer is a cured product of the pressure-sensitive adhesive composition according to any one of claims 1 to 10.
12. A first release sheet is provided on one surface of the pressure-sensitive adhesive layer.
    A second release sheet is provided on the other surface of the pressure-sensitive adhesive layer.
    The adhesive sheet according to claim 11, wherein the first release sheet and the second release sheet have different release forces.
13. A laminate having an adherend on at least one surface of the adhesive sheet according to claim 11.
14. The laminate according to claim 13, which has a metal or a metal oxide on the surface of any layer of the laminate.

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