JP2020176242A - Pressure sensitive adhesive sheet and utilization thereof - Google Patents

Abstract

To provide a pressure sensitive adhesive sheet capable of adhering with good durability even onto an adherend prone to cause outgassing.SOLUTION: A pressure sensitive adhesive sheet has an adhesive layer. The adhesive layer includes an acrylic polymer (A) and a photo reactive monomer (B). The photo reactive monomer (B) is a compound B including two or more ethylenic unsaturated groups and an oxyalkylene structural unit inside a molecule. In the compound B, a molecular weight of the ethylenic unsaturated group per molecule is 250 or less, for instance.SELECTED DRAWING: None

Description

The present invention relates to an adhesive sheet, an optical member with an adhesive sheet, and a method for manufacturing a laminate.

In general, a pressure-sensitive adhesive (also referred to as a pressure-sensitive adhesive; the same applies hereinafter) exhibits a soft solid state (viscoelastic body) in a temperature range near room temperature, and has a property of easily adhering to an adherend by pressure. Taking advantage of these properties, the pressure-sensitive adhesive is widely used in various fields in the form of a pressure-sensitive adhesive sheet with a support having a pressure-sensitive adhesive layer on the support or in the form of a support-less pressure-sensitive adhesive sheet without a support. It's being used. For example, in various optical applications such as optical input devices such as touch panels and display devices such as liquid crystal display devices, adhesives are used for the purpose of joining optical members such as polarizing plates. Patent Document 1 is mentioned as a technical document relating to an optical pressure-sensitive adhesive sheet.

Japanese Unexamined Patent Publication No. 2014-156552

Patent Document 1 describes an adhesive layer having excellent adhesion to an adherend at a high temperature (for example, 85 ° C.), step absorption, and foam resistance at a step portion, and an optical pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer. Is described. Here, in Patent Document 1, the stepped portion foam resistance means the performance that foaming does not occur in the stepped portion under high temperature conditions (paragraph 0003), and in the embodiment, a glass plate having a stepped surface is adhered. The foam resistance of the stepped portion is evaluated as (Paragraph 0113).

By the way, some adherends of the adhesive sheet generate so-called outgas under conditions such as a high temperature environment. In such an adherend, even if a good sticking state without air bubbles is once realized between the adhesive sheet and the adherend, the outgas from the adherend then causes the interface between the adhesive sheet and the adherend. It is possible that new bubbles may be formed by accumulating in the air. The generation (foaming) of such bubbles can reduce the contact area of the adhesive sheet with the adherend, and can lead to a decrease in the reliability of bonding by the adhesive sheet. Therefore, the adhesive sheet, which is expected to be bonded to an adherend that easily generates outgas, suppresses the formation of the bubbles even if it is held in a high temperature environment after being attached to the adherend. It is desirable that it is configured so that it can adhere to the surface with good durability.

Therefore, an object of the present invention is to provide an adhesive sheet that can be durablely adhered to an adherend that easily generates outgas. Another object of the present invention is to provide an optical member with an adhesive sheet configured to include the adhesive sheet. Still another object of the present invention is to provide a method for producing a laminate using the pressure-sensitive adhesive sheet.

According to this specification, a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer is provided. The pressure-sensitive adhesive layer contains an acrylic polymer (A) and a photoreactive monomer (B). As the photoreactive monomer (B), compound B having two or more ethylenically unsaturated groups and an oxyalkylene structural unit (hereinafter, also referred to as “AO unit”) in the molecule is used. The pressure-sensitive adhesive sheet provided with such a pressure-sensitive adhesive layer suppresses the formation of bubbles due to outgas by photo-curing (for example, ultraviolet-curing) the pressure-sensitive adhesive layer after being attached to the adherend, and has durability of adhesion to the adherend. You can improve your sex. The compound B used as the photoreactive monomer (B) preferably has a molecular weight per ethylenically unsaturated group (hereinafter, also referred to as “functional group equivalent”) of the compound B of 250 or less. .. According to such compound B, the durability and other properties (for example, peel strength) tend to be more well-balanced after photocuring.

In some aspects of the pressure-sensitive adhesive sheet disclosed herein, the pressure-sensitive adhesive layer preferably contains 35 mmol or more of ethylenically unsaturated groups per 100 g of the acrylic polymer. Hereinafter, the number of moles of ethylenically unsaturated groups per 100 g of acrylic polymer (per hundred grams of polymer; phgp) may be referred to as “functional group concentration” (unit: mmol (phgp)). By setting the functional group concentration of the ethylenically unsaturated group in the pressure-sensitive adhesive layer to 35 mmol (phgp) or more, the durability of adhesion of the pressure-sensitive adhesive layer to the adherend after photo-curing can be effectively enhanced.

In some embodiments, the content of the photoreactive monomer (B) in the pressure-sensitive adhesive layer is preferably more than 0 parts by weight and less than 20 parts by weight with respect to 100 parts by weight of the acrylic polymer. .. Setting the content of the photoreactive monomer (B) in the above range may be advantageous from the viewpoint of processability and handleability of the pressure-sensitive adhesive sheet before it is attached to the adherend.

In some embodiments, the shear storage elastic modulus of the pressure-sensitive adhesive layer at 85 ° C. after photocuring (hereinafter, also referred to as “post-curing elastic modulus”) is preferably 30 kPa or more. A pressure-sensitive adhesive sheet having such a pressure-sensitive adhesive layer exhibiting a post-curing elastic modulus tends to adhere to an adherend with good durability after photo-curing.

In some embodiments, the shear storage elastic modulus (post-curing elastic modulus) of the pressure-sensitive adhesive layer at 85 ° C. after photocuring is preferably 65 kPa or less. According to the pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer showing the elastic modulus after curing, it is easy to balance the durability of adhesion to the adherend and other characteristics (for example, peel strength) after photo-curing in a well-balanced manner.

In some aspects of the pressure-sensitive adhesive sheet disclosed herein, the shear storage elastic modulus (hereinafter also referred to as "initial elastic modulus") of the pressure-sensitive adhesive layer at 85 ° C. may be, for example, less than 30 kPa. The pressure-sensitive adhesive layer having such an initial elastic modulus has good followability to the surface shape of the adherend. A pressure-sensitive adhesive sheet having such a pressure-sensitive adhesive layer is preferable because it easily adheres well to the adherend at the initial stage of attachment to the adherend (for example, has good step followability).

The pressure-sensitive adhesive sheet disclosed here preferably has a peel strength measured by the following procedure, for example, 5.0 N / 10 mm or more. According to a pressure-sensitive adhesive sheet exhibiting such peel strength (for example, a double-sided pressure-sensitive adhesive sheet, typically a supportless double-sided pressure-sensitive adhesive sheet composed of a single-layer pressure-sensitive adhesive layer), highly durable and reliable bonding can be suitably realized.
[Peeling strength measurement procedure]
The surface of the pressure-sensitive adhesive layer is pressure-bonded to a glass plate by reciprocating a 2 kg rubber roller once, autoclaving (50 ° C., 0.5 MPa, 15 minutes), and then the integrated light amount of 3000 mJ / cm from the glass plate side. The pressure-sensitive adhesive layer is photo-cured by irradiating with the ultraviolet rays of No. ² , and then the peeling strength at the time of peeling from the glass plate is measured under the conditions of a tensile speed of 300 mm / min and a peeling angle of 180 ° in an atmosphere of 25 ° C. ..

In some embodiments, the number of oxyalkylene structural units of the photoreactive monomer (B) is less than 2.0 (eg, 1.0 or more) per ethylenically unsaturated group of the compound. It is preferably less than 2.0). The technique disclosed herein can be preferably carried out using such a photoreactive monomer (B).

According to this specification, an optical member with an adhesive sheet is provided, which includes any of the adhesive sheets disclosed herein and an optical member bonded to one surface of the adhesive sheet. The optical member may be one in which the generation of bubbles is suitably suppressed even under high temperature conditions.

According to this specification, any of the pressure-sensitive adhesive sheets disclosed herein is attached to an adherend, and the pressure-sensitive adhesive sheet is irradiated with ultraviolet rays to photo-cure the pressure-sensitive adhesive layer, in this order. A method for producing a laminate is provided. According to such a method, it is possible to produce a laminated body in which the formation of bubbles is suppressed and the bonding reliability is high.

In addition, an appropriate combination of the above-mentioned elements may be included in the scope of the invention for which protection by the patent is sought by the present patent application.

It is sectional drawing which shows typically the structure of the pressure-sensitive adhesive sheet which concerns on one Embodiment. It is sectional drawing which shows typically the structure of the pressure-sensitive adhesive sheet which concerns on another embodiment. It is sectional drawing which shows typically the optical member with the adhesive sheet which attached the adhesive sheet which concerns on one Embodiment to an optical member.

Hereinafter, preferred embodiments of the present invention will be described. Matters other than those specifically mentioned in the present specification and necessary for the implementation of the present invention are based on the teachings regarding the implementation of the invention described in the present specification and the common general knowledge at the time of filing. Can be understood by those skilled in the art. The present invention can be carried out based on the contents disclosed in the present specification and common general technical knowledge in the art. Further, in the following drawings, members / parts having the same action may be described with the same reference numerals, and duplicate description may be omitted or simplified. In addition, the embodiments described in the drawings are schematicized for clearly explaining the present invention, and do not necessarily accurately represent the size and scale of the actually provided product.

In the present specification, the "acrylic polymer" refers to a polymer derived from a monomer component containing an acrylic monomer in an amount of 50% by weight or more, and is also referred to as an acrylic polymer. The acrylic monomer refers to a monomer derived from a monomer having at least one (meth) acryloyl group in one molecule. Further, in this specification, "(meth) acryloyl" means a comprehensively referring to acryloyl and methacryloyl. Similarly, "(meth) acrylate" means acrylate and methacrylate, and "(meth) acrylic" means acrylic and methacrylic, respectively.

In the present specification, the "photoreactive monomer" is a compound having at least one functional group (photoreactive functional group) in the molecule capable of advancing the reaction by light irradiation, and is typically the above-mentioned photoreactive monomer. It is a compound having at least one ethylenically unsaturated group in the molecule as a functional group. The photoreactive monomer referred to here may be any one capable of causing a reaction as a monomer, and for example, it itself has a polymer such as an oligomer or a polymer (for example, at least one ethylenically unsaturated group in the molecule). It may be a polymer).

<Structure example of adhesive sheet>
An example of the configuration of the pressure-sensitive adhesive sheet disclosed herein is shown in FIG. The adhesive sheet 1 includes an adhesive layer 10 in which one surface 10A is a surface (adhesive surface) to be attached to an adherend, and a support 20 laminated on the other surface 10B of the adhesive layer 10. It is configured as a single-sided adhesive adhesive sheet containing. The pressure-sensitive adhesive layer 10 is bonded to one surface 20A of the support 20. As the support 20, a plastic film such as a polyester film can be used. The support 20 may be an optical film such as a polarizing plate. In the example shown in FIG. 1, the pressure-sensitive adhesive layer 10 has a single-layer structure. As shown in FIG. 1, for example, the adhesive sheet 1 before use (before being attached to the adherend) has a release liner 30 having an adhesive surface 10A having at least the adhesive layer side as a peelable surface (peeling surface). It may be in the form of an adhesive sheet 50 with a release liner protected by. Alternatively, the second surface 20B of the support 20 (the surface opposite to the first surface 20A, also referred to as the back surface) is a peeling surface, and the adhesive surface 10A is on the second surface 20B of the support 20. The adhesive surface 10A may be protected by being wound or laminated so as to be in contact with each other.

The release liner is not particularly limited, and for example, a release liner in which the surface of a liner base material such as a resin film or paper is peeled off, a fluorine-based polymer (polytetrafluoroethylene, etc.), a polyolefin-based resin (polyethylene, polypropylene, etc.) ), A release liner made of a low-adhesive material or the like can be used. For the peeling treatment, for example, a silicone-based or long-chain alkyl-based peeling treatment agent can be used. In some embodiments, the stripped resin film can be preferably used as the strip liner.

The pressure-sensitive adhesive sheet disclosed herein may be in the form of a supportless double-sided pressure-sensitive adhesive sheet composed of a pressure-sensitive adhesive layer. As shown in FIG. 2, in the supportless double-sided pressure-sensitive adhesive sheet 2, before use, each side surface 10A, 10B of the pressure-sensitive adhesive layer 10 is peeled off so that at least the pressure-sensitive adhesive layer side is a peelable surface (peeling surface). It may be in the form protected by the liners 31 and 32. Alternatively, the back surface of the release liner 31 (the surface opposite to the adhesive side) is the release surface, and the adhesive surface is wound or laminated so that the adhesive surface 10B abuts on the back surface of the release liner 31. 10A and 10B may be in a protected form. Such a support-less double-sided pressure-sensitive adhesive sheet can be used, for example, by bonding a support to the surface of any one of the pressure-sensitive adhesive layers.

The pressure-sensitive adhesive sheet disclosed herein can be a component of an optical member with a pressure-sensitive adhesive sheet to which an optical member is bonded to one surface of a pressure-sensitive adhesive layer. For example, the pressure-sensitive adhesive sheet 1 shown in FIG. 1 can be a component of an optical member 100 with a pressure-sensitive adhesive sheet in which an optical member 70 is bonded to one surface 10A of the pressure-sensitive adhesive layer 10, as shown in FIG. The optical member may be, for example, a glass plate, a resin film, a metal plate, or the like.
In some embodiments, the optical member preferably has a non-water-absorbing smooth surface to which the pressure-sensitive adhesive layer is bonded. An optical member with an adhesive sheet having such a structure can be easily reattached (reworked) to, for example, the adherend by applying a water peeling method described later as necessary.
In some embodiments, the optical member may be hydrophilized on the surface to which the pressure-sensitive adhesive layer is bonded. Examples of the hydrophilic treatment include treatments that contribute to the improvement of hydrophilicity, such as corona treatment, plasma treatment, and hydrophilic coating treatment for providing a hydrophilic coating layer. The hydrophilization treatment can improve the reworkability by the water peeling method described later.

<Adhesive layer>
The pressure-sensitive adhesive sheet disclosed herein has a pressure-sensitive adhesive layer containing an acrylic polymer (A) and a photoreactive monomer (B). In a preferred embodiment, the pressure-sensitive adhesive layer may be an acrylic pressure-sensitive adhesive layer containing the acrylic polymer (A) as a main component (typically, a component contained in an amount of more than 50% by weight).

(Acrylic polymer (A))
The acrylic polymer (A) is typically a polymer derived from a monomer component containing more than 50% by weight of an acrylic monomer, and has a linear or branched chain having 1 to 20 carbon atoms at the ester terminal. It is preferable that the acrylic polymer is composed of a monomer component containing a (meth) acrylic acid alkyl ester having an alkyl group in a proportion of 40% by weight or more. Hereinafter, a (meth) acrylic acid alkyl ester having an alkyl group having an number of carbon atoms of X or more and Y or less at the ester terminal may be referred to as "(meth) acrylic acid _CXY alkyl ester". Since it is easy to balance the characteristics, it is appropriate that the proportion of (meth) acrylic acid C _1-20 alkyl ester in the total monomer component of the acrylic polymer (A) according to one embodiment is more than 50% by weight. Yes, for example, it may be 55% by weight or more, 60% by weight or more, or 70% by weight or more. For the same reason, the proportion of the (meth) acrylic acid C _1-20 alkyl ester in the monomer component may be, for example, 99.9% by weight or less, 99.5% by weight or less, or 99% by weight or less. Good. The ratio of the C _1-20 (meth) acrylic acid alkyl ester to the total monomer component of the acrylic polymer (A) according to the other aspect may be, for example, 98% by weight or less, and the cohesiveness of the pressure-sensitive adhesive layer is improved. From the viewpoint of the above, it may be 95% by weight or less, 85% by weight or less (for example, less than 80% by weight), 70% by weight or less, or 60% by weight or less.

Non-limiting specific examples of (meth) acrylic acid C _1-20 alkyl ester include methyl (meth) acrylic acid, ethyl (meth) acrylic acid, propyl (meth) acrylic acid, isopropyl (meth) acrylic acid, ( N-butyl acrylate, isobutyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, (meth) Hexyl acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, (meth) ) Decyl acrylate, Isodecyl (meth) acrylate, Undecyl (meth) acrylate, Dodecyl (meth) acrylate, Tridecyl (meth) acrylate, Tetradecyl (meth) acrylate, Pentadecyl (meth) acrylate, (meth) Examples thereof include hexadecyl acrylate, heptadecyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, nonadecil (meth) acrylate, and eicocil (meth) acrylate.

Of these, it is preferable to use at least (meth) acrylic acid C _4-20 alkyl ester, and it is more preferable to use at least (meth) acrylic acid C _4-18 alkyl ester. Particularly preferred (meth) acrylic acid C _4-18 alkyl esters include n-butyl acrylate (BA) and 2-ethylhexyl acrylate (2EHA). Other specific examples of (meth) acrylic acid C _4-20 alkyl esters that may be preferably used include isononyl acrylate, n-butyl methacrylate (BMA), 2-ethylhexyl methacrylate (2EHMA), isostearyl acrylate ( iSTA) and the like. These (meth) acrylic acid C _4-20 alkyl esters can be used alone or in combination of two or more.

The monomer component preferably contains, for example, either one or both of n-butyl acrylate (BA) and 2-ethylhexyl acrylate (2EHA). In some embodiments, the monomer component preferably comprises at least BA. Here, at least the example of the monomer component containing BA includes a monomer component having a composition containing BA and not containing 2EHA, BA and 2EHA, and the content of 2EHA is less than the content of BA (for example, the content of 2EHA). Contains monomer components of composition (the amount is less than 0.5 times or less than 0.3 times the content of BA).

In some embodiments, the monomer component constituting the acrylic polymer (A) may contain (meth) acrylic acid C _4-18 alkyl ester in a proportion of 40% by weight or more. The ratio of the (meth) acrylic acid C _4-18 alkyl ester to the monomer component may be, for example, 50% by weight or more, 60% by weight or more, or 65% by weight or more.
Further, from the viewpoint of enhancing the cohesiveness of the pressure-sensitive adhesive layer, it is usually appropriate that the ratio of the (meth) acrylic acid C _4-18 alkyl ester to the monomer component is 99.5% by weight or less, and 95% by weight. It may be% or less, 85% by weight or less, and 75% by weight or less.

The monomer component constituting the acrylic polymer (A) contains (meth) acrylic acid alkyl ester and, if necessary, other monomer (copolymerizable monomer) copolymerizable with (meth) acrylic acid alkyl ester. You may be. As the copolymerizable monomer, a monomer having a polar group (for example, a carboxy group, a hydroxyl group, a nitrogen atom-containing ring, etc.) or a monomer having a relatively high glass transition temperature of a homopolymer (for example, 10 ° C. or higher) is preferably used. can do. The monomer having a polar group can be useful for introducing a cross-linking point in the acrylic polymer (A) and increasing the cohesive force of the pressure-sensitive adhesive. The copolymerizable monomer may be used alone or in combination of two or more.

Non-limiting specific examples of the copolymerizable monomer include the following.
Carboxylic group-containing monomer: For example, acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid and the like.
Acid anhydride group-containing monomer: For example, maleic anhydride, itaconic anhydride.
Hydroxyl group-containing monomers: for example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, (meth) acrylic. 4-Hydroxybutyl acid, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, (4-hydroxy) Methylcyclohexyl) Methyl (meth) acrylate and the like (meth) acrylate hydroxyalkyl and the like.
Monomers containing a sulfonic acid group or a phosphoric acid group: for example, styrene sulfonic acid, allyl sulfonic acid, sodium vinyl sulfonic acid, 2- (meth) acrylamide-2-methylpropane sulfonic acid, (meth) acrylamide propane sulfonic acid, sulfo. Propyl (meth) acrylate, (meth) acryloyloxynaphthalene sulfonic acid, 2-hydroxyethylacryloyl phosphate, etc.
Epoxy group-containing monomer: For example, epoxy group-containing acrylate such as (meth) glycidyl acrylate and -2-ethyl glycidyl ether (meth) acrylate, allyl glycidyl ether, glycidyl ether (meth) acrylate and the like.
Cyano group-containing monomer: For example, acrylonitrile, methacrylonitrile, etc.
Isocyanate group-containing monomer: For example, 2-isocyanate ethyl (meth) acrylate and the like.
Amide group-containing monomers: For example, (meth) acrylamide; N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N, N-dipropyl (meth) acrylamide, N, N-diisopropyl (meth). N, N-dialkyl (meth) acrylamide such as acrylamide, N, N-di (n-butyl) (meth) acrylamide, N, N-di (t-butyl) (meth) acrylamide; N-ethyl (meth) acrylamide , N-alkyl (meth) acrylamide such as N-isopropyl (meth) acrylamide, N-butyl (meth) acrylamide, Nn-butyl (meth) acrylamide; N-vinylcarboxylic acid amides such as N-vinylacetamide; Monomers having a hydroxyl group and an amide group, for example, N- (2-hydroxyethyl) (meth) acrylamide, N- (2-hydroxypropyl) (meth) acrylamide, N- (1-hydroxypropyl) (meth) acrylamide, N- (3-Hydroxypropyl) (meth) acrylamide, N- (2-hydroxybutyl) (meth) acrylamide, N- (3-hydroxybutyl) (meth) acrylamide, N- (4-hydroxybutyl) (meth) N-Hydroxyalkyl (meth) acrylamide such as acrylamide; monomers having an alkoxy group and an amide group, for example, N-methoxymethyl (meth) acrylamide, N-methoxyethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide. N-alkoxyalkyl (meth) acrylamide such as N, N-dimethylaminopropyl (meth) acrylamide, N- (meth) acryloylmorpholine and the like.
Amino group-containing monomer: For example, aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, t-butylaminoethyl (meth) acrylate.
Monomers having an epoxy group: for example, glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, allyl glycidyl ether.
Monomers having a nitrogen atom-containing ring: for example, N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N- Vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N- (meth) acryloyl-2-pyrrolidone, N- (meth) acryloyl piperidine, N- (meth) acryloylpyrrolidin, N-vinylmorpholin, N-vinyl-3 -Morholinone, N-vinyl-2-caprolactam, N-vinyl-1,3-oxadin-2-one, N-vinyl-3,5-morpholindione, N-vinylpyrazole, N-vinylisoxazole, N-vinyl Thiazol, N-vinylisothiazole, N-vinylpyridazine and the like (eg, lactams such as N-vinyl-2-caprolactam).
Monomers having a succinimide skeleton: for example, N- (meth) acryloyloxymethylene succinimide, N- (meth) acryloyl-6-oxyhexamethylene succinimide, N- (meth) acryloyl-8-oxyhexamethylene succinimide and the like.
Maleimides: For example, N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide and the like.
Itaconimides: For example, N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, N-lauryl Itaconimide, etc.
Aminoalkyl (meth) acrylates: For example, aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, t (meth) acrylate. -Butylaminoethyl.
Alkoxy group-containing monomers: for example, 2-methoxyethyl (meth) acrylate, 3-methoxypropyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, propoxyethyl (meth) acrylate, (meth) acrylate. (Meta) alkoxyalkyl acrylates (alkoxyalkyl (meth) acrylates) such as butoxyethyl, ethoxypropyl (meth) acrylate; methoxyethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, (meth) (Meta) Acrylic acid alkoxyalkylene glycols such as methoxypolypropylene glycol acrylate (for example, alkoxypolyalkylene glycol (meth) acrylate).
Alkoxysilyl group-containing monomers: for example, 3- (meth) acryloxypropyltrimethoxysilane, 3- (meth) acryloxypropyltriethoxysilane, 3- (meth) acryloxipropylmethyldimethoxysilane, 3- (meth) acryloxy. Alkoxysilyl group-containing (meth) acrylates such as propylmethyldiethoxysilane, alkoxysilyl group-containing vinyl compounds such as vinyltrimethoxysilane and vinyltriethoxysilane, and the like.
Vinyl esters: For example, vinyl acetate, vinyl propionate and the like.
Vinyl ethers: For example, vinyl alkyl ethers such as methyl vinyl ether and ethyl vinyl ether.
Aromatic vinyl compounds: for example, styrene, α-methylstyrene, vinyltoluene and the like.
Olefins: For example, ethylene, butadiene, isoprene, isobutylene and the like.
(Meta) acrylic acid ester having an alicyclic hydrocarbon group: For example, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, adamantyl (meth) acrylate and the like. Acrylate-type hydrocarbon group-containing (meth) acrylate.
(Meta) acrylic acid ester having an aromatic hydrocarbon group: For example, an aromatic hydrocarbon group-containing (meth) acrylate such as phenyl (meth) acrylate, phenoxyethyl (meth) acrylate, and benzyl (meth) acrylate.
In addition, heterocyclic-containing (meth) acrylates such as tetrahydrofurfuryl (meth) acrylate, halogen atom-containing (meth) acrylates such as vinyl chloride and fluorine atom-containing (meth) acrylates, and silicon atom-containing silicone (meth) acrylates. (Meta) acrylate, (meth) acrylic acid ester obtained from terpene compound derivative alcohol, etc.

When such a copolymerizable monomer is used, the amount used is not particularly limited, but it is usually appropriate to use 0.01% by weight or more of the total monomer component. From the viewpoint of better exerting the effect of using the copolymerizable monomer, the amount of the copolymerizable monomer used may be 0.1% by weight or more of the entire monomer component, or 0.5% by weight or more. Further, from the viewpoint of facilitating the balance of the adhesive properties, the amount of the copolymerizable monomer used is usually preferably 50% by weight or less of the total monomer component, and preferably 40% by weight or less.

で表わされるＮ−ビニル環状アミドを用いることができる。ここで、一般式（１）中、Ｒ¹は２価の有機基であり、具体的には−（ＣＨ₂）_ｎ−である。ｎは２〜７（好ましくは２，３または４）の整数である。なかでも、Ｎ−ビニル−２−ピロリドンを好ましく採用し得る。窒素原子を有するモノマーの他の好適例としては、（メタ）アクリルアミドが挙げられる。 In some embodiments, the monomer component constituting the acrylic polymer (A) may include a monomer having a nitrogen atom. By using a monomer having a nitrogen atom, the cohesive force of the pressure-sensitive adhesive can be increased, and the peel strength after photocuring can be preferably improved. A preferred example of a monomer having a nitrogen atom is a monomer having a nitrogen atom-containing ring. As the monomer having a nitrogen atom-containing ring, those exemplified above can be used, and for example, the general formula (1):

The N-vinyl cyclic amide represented by is used. Here, in the general formula (1), R ¹ is a divalent organic group, specifically − (CH ₂ ) _n −. n is an integer of 2 to 7 (preferably 2, 3 or 4). Of these, N-vinyl-2-pyrrolidone can be preferably adopted. Other preferred examples of monomers having a nitrogen atom include (meth) acrylamide.

The amount of the monomer having a nitrogen atom (preferably the monomer having a nitrogen atom-containing ring) is not particularly limited, and may be, for example, 1% by weight or more or 3% by weight or more of the entire monomer component. Further, it can be 5% by weight or more or 7% by weight or more. In one aspect, the amount of the monomer having a nitrogen atom used may be 10% by weight or more, 15% by weight or more, or 20% by weight or more of the total monomer component. Further, the amount of the monomer having a nitrogen atom to be used is appropriately set to, for example, 40% by weight or less of the total monomer component, 35% by weight or less, 30% by weight or less, or 25% by weight or less. May be good. In another aspect, the amount of the monomer having a nitrogen atom used may be, for example, 20% by weight or less of the total monomer component, or 15% by weight or less.

In some embodiments, the monomer component constituting the acrylic polymer (A) may include a hydroxyl group-containing monomer. By using the hydroxyl group-containing monomer, the cohesive force of the pressure-sensitive adhesive and the degree of cross-linking (for example, cross-linking with an isocyanate cross-linking agent) can be suitably adjusted. When a hydroxyl group-containing monomer is used, the amount used is not particularly limited, and may be, for example, 0.01% by weight or more, 0.1% by weight or more, or 0.5% by weight or more of the entire monomer component. It may be 1% by weight or more, 5% by weight or more, or 10% by weight or more. Further, from the viewpoint of suppressing the water absorption of the pressure-sensitive adhesive layer, it is appropriate that the amount of the hydroxyl group-containing monomer used is, for example, 40% by weight or less of the total monomer component, and is 30% by weight or less in some embodiments. It may be 25% by weight or less, or 20% by weight or less. In another aspect, the amount of the hydroxyl group-containing monomer used may be, for example, 15% by weight or less, 10% by weight or less, or 5% by weight or less of the total monomer component.

In the pressure-sensitive adhesive composition disclosed herein, the monomer component of the acrylic polymer (A) may or may not contain the alkoxyalkyl (meth) acrylate and the alkoxypolyalkylene glycol (meth) acrylate exemplified above. Good. In one aspect of the technique disclosed herein, the proportion of alkoxyalkyl (meth) acrylate in the monomer component of the acrylic polymer (A) is less than 20% by weight, and the proportion of alkoxypolyalkylene glycol (meth) acrylate is It is less than 20% by weight. As a result, the pressure-sensitive adhesive layer can easily form a sheet without problems such as gelation. By adopting the above-mentioned monomer composition, the solid concentration of the monomer mixture is kept in a predetermined range desired high molecular weight (e.g., weight average molecular weight (Mw) 30 × 10 ⁴ greater, typically Mw40 × 10 ⁴ The above) can be preferably polymerized. The proportion of the alkoxyalkyl (meth) acrylate in the monomer component is preferably less than 10% by weight, more preferably less than 3% by weight, still more preferably less than 1% by weight, and in a particularly preferable aspect, the monomer component is It is substantially free of alkoxyalkyl (meth) acrylates (content 0-0.3% by weight). Similarly, the proportion of the alkoxypolyalkylene glycol (meth) acrylate in the monomer component is preferably less than 10% by weight, more preferably less than 3% by weight, still more preferably less than 1% by weight, and in one particularly preferred embodiment. , The above-mentioned monomer component substantially does not contain alkoxypolyalkylene glycol (meth) acrylate (content 0 to 0.3% by weight).

Further, in the monomer component of the acrylic polymer (A) according to the preferred embodiment, the total ratio of the alkoxyalkyl (meth) acrylate and the alkoxypolyalkylene glycol (meth) acrylate is limited to less than 20% by weight from the viewpoint of suppressing gelation. Has been done. The total proportion of the alkoxyalkyl (meth) acrylate and the alkoxypolyalkylene glycol (meth) acrylate is more preferably less than 10% by weight, further preferably less than 3% by weight, particularly preferably less than 1% by weight, in one embodiment. , The monomer component is substantially free of alkoxyalkyl (meth) acrylate and alkoxypolyalkylene glycol (meth) acrylate (content 0 to 0.3% by weight).
Similarly, the monomer component of the acrylic polymer (A) disclosed herein may or may not contain an alkoxy group-containing monomer in a proportion of less than 20% by weight. The amount of the alkoxy group-containing monomer in the monomer component is preferably less than 10% by weight, more preferably less than 3% by weight, still more preferably less than 1% by weight, and in a particularly preferable aspect, the monomer component is an alkoxy group. It contains substantially no monomer (content 0 to 0.3% by weight).

In some embodiments, the proportion of the carboxy group-containing monomer in the monomer component of the acrylic polymer (A) may be, for example, 2% by weight or less, 1% by weight or less, and 0.5% by weight or less (for example). It may be less than 0.1% by weight). It is not necessary to substantially use a carboxy group-containing monomer as the monomer component of the acrylic polymer (A). Here, the fact that the carboxy group-containing monomer is not substantially used means that the carboxy group-containing monomer is not used at least intentionally. The acrylic polymer (A) having such a composition tends to have high water resistance and reliability, and can have metal corrosion prevention properties for an adherend containing a metal.

Further, in a preferred embodiment, the proportion of the hydrophilic monomer in the monomer component of the acrylic polymer (A) is set in an appropriate range. As a result, the water releasability described later is preferably exhibited. Here, the "hydrophilic monomer" in the present specification contains a carboxy group-containing monomer, an acid anhydride group-containing monomer, a hydroxyl group-containing monomer, a monomer having a nitrogen atom (typically, an amide group such as (meth) acrylamide). Monomer, monomer having a nitrogen atom-containing ring such as N-vinyl-2-pyrrolidone) and alkoxy group-containing monomer (typically, alkoxyalkyl (meth) acrylate and alkoxypolyalkylene glycol (meth) acrylate). To do. In this embodiment, the proportion of the hydrophilic monomer in the monomer component of the acrylic polymer (A) is preferably 32% by weight or less, for example, 30% by weight or less, and 28% by weight or less. May be good. Although not particularly limited, the proportion of the hydrophilic monomer in the monomer component of the acrylic polymer (A) may be 1% by weight or more, 10% by weight or more, or 20% by weight. It may be the above.

In some embodiments, the monomer component constituting the acrylic polymer (A) may include an alicyclic hydrocarbon group-containing (meth) acrylate. As a result, the cohesive force of the pressure-sensitive adhesive can be increased, and the peel strength after photo-curing can be improved. As the alicyclic hydrocarbon group-containing (meth) acrylate, those exemplified above can be used, and for example, cyclohexyl acrylate and isobornyl acrylate can be preferably adopted. When the alicyclic hydrocarbon group-containing (meth) acrylate is used, the amount used is not particularly limited, and may be, for example, 1% by weight or more, 3% by weight or more, or 5% by weight or more of the total monomer component. In one aspect, the amount of the alicyclic hydrocarbon group-containing (meth) acrylate used may be 10% by weight or more of the total monomer component, or 15% by weight or more. The upper limit of the amount of the alicyclic hydrocarbon group-containing (meth) acrylate used is appropriately about 40% by weight or less, for example, 30% by weight or less, and 25% by weight or less (for example, 15% by weight). % Or less, and even 10% by weight or less).

The composition of the monomer component constituting the acrylic polymer (A) can be set so that the glass transition temperature Tg determined by the Fox formula based on the composition of the monomer component is −75 ° C. or higher and 10 ° C. or lower. In some embodiments, the Tg is preferably 0 ° C. or lower, preferably −10 ° C. or lower, and preferably −20 ° C. or lower or −30 ° C. or lower, from the viewpoint of cohesiveness, impact resistance, and the like. It may be as follows. Further, the Tg may be, for example, −60 ° C. or higher, −50 ° C. or higher, −45 ° C. or higher, or −40 ° C. or higher.

Here, the Fox formula is a relational formula between the Tg of the copolymer and the glass transition temperature Tgi of the homopolymer in which each of the monomers constituting the copolymer is homopolymerized, as shown below. ..
1 / Tg = Σ (Wi / Tgi)
In the Fox formula, Tg is the glass transition temperature (unit: K) of the copolymer, Wi is the weight fraction of the monomer i in the copolymer (copolymerization ratio based on the weight), and Tgi is the monomer i. Represents the glass transition temperature (unit: K) of the homopolymer.

As the glass transition temperature of the homopolymer used for calculating Tg, the value described in the publicly known material shall be used. For example, for the monomers listed below, the following values are used as the glass transition temperature of the homopolymer of the monomer.
2-Ethylhexyl acrylate-70 ° C
n-Butyl acrylate -55 ° C
Isostearyl acrylate -18 ° C
Methyl methacrylate 105 ° C
Methyl acrylate 8 ℃
Cyclohexyl acrylate 15 ° C
N-Vinyl-2-pyrrolidone 54 ° C
2-Hydroxyethyl acrylate -15 ° C
4-Hydroxybutyl acrylate-40 ° C
Dicyclopentanyl methacrylate 175 ° C
Isobornyl acrylate 94 ° C
Acrylic acid 106 ℃
Methacrylic acid 228 ° C

For the glass transition temperature of homopolymers of monomers other than those exemplified above, the numerical values described in "Polymer Handbook" (3rd edition, John Wiley & Sons, Inc., 1989) shall be used. When multiple types of values are described in this document, the highest value is adopted.

For the monomer in which the glass transition temperature of the homopolymer is not described in the Polymer Handbook, the value obtained by the following measurement method shall be used (see JP-A-2007-51271). Specifically, in a reactor equipped with a thermometer, a stirrer, a nitrogen introduction tube and a reflux condenser, 100 parts by weight of a monomer, 0.2 parts by weight of azobisisobutyronitrile and 200 parts by weight of ethyl acetate as a polymerization solvent were added. Add and stir for 1 hour with nitrogen gas flowing. After removing oxygen in the polymerization system in this way, the temperature is raised to 63 ° C. and the reaction is carried out for 10 hours. Then, the mixture is cooled to room temperature to obtain a homopolymer solution having a solid content concentration of 33% by weight. Next, this homopolymer solution is cast-coated on a release liner and dried to prepare a test sample (sheet-shaped homopolymer) having a thickness of about 2 mm. This test sample is punched into a disk shape with a diameter of 7.9 mm, sandwiched between parallel plates, and subjected to shear strain at a frequency of 1 Hz using a viscoelasticity tester (ARES, manufactured by Leometrics) in a temperature range of −70 to 150 ° C. The viscoelasticity is measured in a shear mode at a heating rate of 5 ° C./min, and the peak top temperature of tan δ is defined as Tg of the homopolymer.

The acrylic polymer (A) in the technique disclosed herein is not particularly limited, but preferably has an SP value of 23.0 (MJ / m ³ ) ^1/2 or less. The pressure-sensitive adhesive containing the acrylic polymer (A) having such an SP value is, for example, by incorporating a water-affinitive agent described later, a pressure-sensitive adhesive sheet having sufficient adhesive strength and excellent water peelability. It can be preferably realized. The SP value is more preferably 21.0 (MJ / m ³ ) ^1/2 or less (for example, 20.0 (MJ / m ³ ) ^1/2 or less). The lower limit of the SP value is not particularly limited, and for example, it is appropriate that it is approximately 10.0 (MJ / m ³ ) ^1/2 or more, and approximately 15.0 (MJ / m ³ ) ^1/2 or more. Yes, preferably 18.0 (MJ / m ³ ) ^1/2 or more.

The SP value of the acrylic polymer (A) is calculated by Fedors ["Polymer Engineering and Science (POLYMER ENG. &SCI.)", Vol. 14, No. 2 (1974), No. 148- See page 154] That is, the formula:
SP value δ = (Σ △ e / Σ △ v) ^1/2
(In the above equation, Δe is the evaporation energy Δe of each atom or atomic group at 25 ° C., and Δv is the molar volume of each atom or atomic group at the same temperature.);
Can be calculated according to. The acrylic polymer (A) having the above SP value can be obtained by appropriately determining the monomer composition based on the common general technical knowledge of those skilled in the art.

The pressure-sensitive adhesive layer disclosed herein is typically prepared from a monomer component having the above-mentioned composition (typically, a mixture containing two or more monomers having one ethylenically unsaturated group in the molecule). It can be formed by using a pressure-sensitive adhesive composition containing the acrylic polymer (A) and the photoreactive monomer (B). The form of the pressure-sensitive adhesive composition is not particularly limited. For example, a water-dispersible pressure-sensitive adhesive composition in which a pressure-sensitive adhesive (adhesive component) is dispersed in water, or a solvent-type pressure-sensitive adhesive in which the pressure-sensitive adhesive is contained in an organic solvent The composition may be in various conventionally known forms such as a hot melt type pressure-sensitive adhesive composition which is coated in a heat-melted state and forms a pressure-sensitive adhesive when cooled to around room temperature.

From the viewpoint of ease of preparation of the pressure-sensitive adhesive composition, ease of formation of the pressure-sensitive adhesive layer, and the like, the solvent-type pressure-sensitive adhesive composition can be preferably adopted in some embodiments. The solvent-based pressure-sensitive adhesive composition typically comprises an acrylic polymer (A), which is a solution polymerization of the monomer components, a photoreactive monomer (B), and other components (eg,) used as needed. It contains one or more of a photopolymerization initiator, a cross-linking agent, an acrylic oligomer, a water-affinitive agent, etc., which will be described later. The solvent (polymerization solvent) used for solution polymerization can be appropriately selected from conventionally known organic solvents. For example, aromatic compounds such as toluene (typically aromatic hydrocarbons); esters such as ethyl acetate and butyl acetate; aliphatic or alicyclic hydrocarbons such as hexane and cyclohexane; 1,2- Select from halogenated alkanes such as dichloroethane; lower alcohols such as isopropyl alcohol (for example, monohydric alcohols having 1 to 4 carbon atoms); ethers such as tert-butylmethyl ether; ketones such as methyl ethyl ketone; etc. Any one solvent or a mixed solvent of two or more can be used. By solution polymerization, a polymerization reaction solution in which a polymer of a monomer component is dissolved in a polymerization solvent can be obtained. The solvent-based pressure-sensitive adhesive composition used for forming the pressure-sensitive adhesive layer disclosed herein can be preferably produced using the above-mentioned polymerization reaction solution.

The polymerization method for forming (synthesizing) the acrylic polymer (A) from the monomer component is not particularly limited, and various conventionally known polymerization methods can be appropriately adopted. For example, thermal polymerization such as solution polymerization, emulsion polymerization, bulk polymerization (typically performed in the presence of a thermal polymerization initiator); photopolymerization performed by irradiating light such as ultraviolet rays (typically). A polymerization method such as radiation polymerization carried out by irradiating radiation such as β-ray or γ-ray; which is carried out in the presence of a photopolymerization initiator; can be appropriately adopted. Two or more polymerization methods may be combined (eg, stepwise).

In the polymerization, a known or commonly used thermal polymerization initiator or photopolymerization initiator may be used depending on the polymerization method, polymerization mode and the like. Such a polymerization initiator may be used alone or in combination of two or more.

The thermal polymerization initiator is not particularly limited, but is, for example, an azo-based polymerization initiator, a peroxide-based initiator, a redox-based initiator by a combination of a peroxide and a reducing agent, and a substituted ethane-based initiator. Etc. can be used. More specifically, for example, 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis (2-methylpropionamidine) disulfate, 2,2'-azobis (2-amidinopropane). ) Dihydrochloride, 2,2'-azobis [2- (5-methyl-2-imidazolin-2-yl) propane] dihydrochloride, 2,2'-azobis (N, N'-dimethyleneisobutyramidine), 2 , 2'-Azobis [N- (2-carboxyethyl) -2-methylpropionamidine] Azo-based initiators such as hydrate; persulfates such as potassium persulfate and ammonium persulfate; benzoyl peroxide, t-butyl Peroxide-based initiators such as hydroperoxide and hydrogen peroxide; for example, substituted ethane-based initiators such as phenyl-substituted ethane; for example, a combination of persulfate and sodium hydrogen sulfite, and a combination of peroxide and sodium ascorbate. Redox-based initiators such as; etc., but are not limited thereto. Thermal polymerization can be preferably carried out at a temperature of, for example, about 20 to 100 ° C. (typically 40 to 80 ° C.), but is not limited thereto.

The photopolymerization initiator is not particularly limited, but for example, a ketal-based photopolymerization initiator, an acetophenone-based photopolymerization initiator, a benzoin ether-based photopolymerization initiator, an acylphosphine oxide-based photopolymerization initiator, α- Ketol-based photopolymerization initiator, aromatic sulfonyl chloride-based photopolymerization initiator, photoactive oxime-based photopolymerization initiator, benzoin-based photopolymerization initiator, benzyl-based photopolymerization initiator, benzophenone-based photopolymerization initiator, thioxanthone-based light A polymerization initiator or the like can be used.

The amount of the polymerization initiator used can be a normal amount depending on the polymerization method, polymerization mode, etc., and is not particularly limited. For example, about 0.001 to 5 parts by weight of the polymerization initiator (typically about 0.01 to 2 parts by weight, for example, about 0.01 to 1 part by weight) is used with respect to 100 parts by weight of the monomer to be polymerized. Can be done.

For the above-mentioned polymerization, various conventionally known chain transfer agents (which can also be grasped as a molecular weight adjusting agent or a degree of polymerization adjusting agent) can be used, if necessary. As the chain transfer agent, mercaptans such as n-dodecyl mercaptan, t-dodecyl mercaptan, thioglycolic acid, and α-thioglycerol can be used. Alternatively, a chain transfer agent containing no sulfur atom (non-sulfur chain transfer agent) may be used. Specific examples of the non-sulfur chain transfer agent include anilins such as N, N-dimethylaniline and N, N-diethylaniline; terpenoids such as α-pinene and turpinolene; α-methylstyrene and α-methylstyrene dimer. Such as styrenes; compounds having a benzylidenyl group such as dibenzylidene acetone, cinnamyl alcohol, cinnamyl aldehyde; hydroquinones such as hydroquinone and naphthohydroquinone; quinones such as benzoquinone and naphthoquinone; 2,3-dimethyl-2-butene , 1,5-Cyclooctadiene and the like; alcohols such as phenol, benzyl alcohol and allyl alcohol; benzyl hydrogens such as diphenylbenzene and triphenylbenzene; and the like.
The chain transfer agent may be used alone or in combination of two or more. When a chain transfer agent is used, the amount used can be, for example, about 0.01 to 1 part by weight with respect to 100 parts by weight of the monomer component. The techniques disclosed herein may also be preferably practiced in aspects that do not use chain transfer agents.

The molecular weight of the acrylic polymer (A) obtained by appropriately adopting the above-mentioned various polymerization methods is not particularly limited, and can be set in an appropriate range according to the required performance and the like. The weight average molecular weight of the acrylic polymer (A) (Mw) is usually suitably be at about 10 × 10 ⁴ or more, for example may be at about 15 × 10 ⁴ or more, and a cohesive force and adhesive force from the viewpoint of achieving both good balance is preferably 30 × 10 ⁴ greater. The acrylic polymer (A) according to one embodiment is preferably 40 × 10 ⁴ or more (typically about 50 × 10 ⁴ or more, for example, about 55 ×) from the viewpoint of obtaining good adhesive reliability even in a high temperature environment. having an Mw of 10 ⁴ or more). According to a preferred embodiment of the technique disclosed herein, gelation can be suppressed by designing the monomer composition, so that an appropriate solid content concentration can be set to obtain a high molecular weight substance in the above range with high productivity. The upper limit of the Mw of the acrylic polymer (A) may be usually about 500 × 10 ⁴ or less (e.g., about 0.99 × 10 ⁴ or less). The Mw may be of about 75 × 10 ⁴ or less. Here, Mw refers to a standard polystyrene-equivalent value obtained by gel permeation chromatography (GPC). As the GPC apparatus, for example, the model name "HLC-8320GPC" (column: TSKgelGMH-H (S), manufactured by Tosoh Corporation) may be used. The same applies to the examples described later. The Mw can be the Mw of the acrylic polymer (A) in either the pressure-sensitive adhesive composition or the pressure-sensitive adhesive layer.

(Photoreactive monomer (B))
The pressure-sensitive adhesive layer in the techniques disclosed herein (including a pressure-sensitive adhesive sheet, an optical member with a pressure-sensitive adhesive sheet, a pressure-sensitive adhesive composition, a method for producing a laminate, and a method for peeling off a pressure-sensitive adhesive sheet; the same applies hereinafter) is a photoreactive monomer (B). )including. As the photoreactive monomer (B), a compound having two or more ethylenically unsaturated groups and an oxyalkylene structural unit in the molecule is used. The photoreactive monomer (B) may be used alone or in combination of two or more.

The photoreactive monomer (B) contained in the pressure-sensitive adhesive layer has a crosslinked structure having appropriate flexibility by reacting the ethylenically unsaturated group with light (for example, ultraviolet rays) irradiation after being attached to the adherend. Can form. As a result, it is possible to effectively improve the durability of adhesion to the adherend while suppressing a decrease in the peel strength to the adherend. According to the pressure-sensitive adhesive sheet containing the photoreactive monomer (B) in the pressure-sensitive adhesive layer, it has excellent followability to the surface shape of the adherend when it is attached to the adherend, and the pressure-sensitive adhesive layer is irradiated with ultraviolet rays after the adhesion. By curing the above, the durability of adhesion to the adherend can be enhanced and good peel strength can be exhibited.

Examples of the ethylenically unsaturated group include, but are not limited to, an acryloyl group, a methacryloyl group, a vinyl group and an allyl group. The two or more ethylene unsaturated groups that the photoreactive monomer (B) has in the molecule may be the same group or two or more different groups. Preferred ethylenically unsaturated groups from the viewpoint of photoreactivity include acryloyl group and methacryloyl group. Of these, the acryloyl group is preferable.

The oxyalkylene structural unit (AO unit) refers to a structural unit represented by the general formula (U1): -AO- ;, and is typically represented by the general formula (U2): -C _m H _{2 m} O- ;. The structural unit represented. Here, A in the general formula (U1) is typically an alkylene group having 2 or more carbon atoms, preferably an alkylene group having 2 to 4 carbon atoms. M in the above formula (U2) is an integer of 2 or more, preferably an integer of 2 to 4, and more preferably an integer of 2 to 3. Preferable examples of AO units include oxyethylene units and oxypropylene units. Such AO units can be formed, for example, by modification (addition reaction) with an alkylene oxide or an alkylene glycol.

The photoreactive monomer (B) is a compound containing a repeating structure in which two or more AO units represented by the above general formula (U1) are continuous, that is, a structure represented by the general formula:-(AO) _n- ;. You may. Here, n in the above formula is an integer of 2 or more, for example, an integer of 2 to 10, preferably an integer of 2 to 5, and more preferably an integer of 2 to 3. Alternatively, the photoreactive monomer (B) may be a compound having no repeating structure in which two or more AO units are continuous (the compound may be a compound containing two or more AO units discontinuously). According to such a photoreactive monomer (B), a pressure-sensitive adhesive layer having a good balance between cohesiveness and crosslinking flexibility can be efficiently formed.

The number of the photoreactive monomer (B) is at least one, preferably two or more (for example, about 2 to 4) between one ethylenically unsaturated group and any one of the other ethylenically unsaturated groups. It is more preferable to have a molecular structure in which the AO unit of) is arranged. The two or more AO units may or may not be adjacent to each other to form a − (AO) _n − structure.
In some embodiments, the photoreactive monomer (B) has a molecular structure in which AO units are arranged adjacent to at least a part of the ethylenically unsaturated group contained in the photoreactive monomer (B). It is preferable to do so. AO units placed adjacent to an ethylenically unsaturated group (eg, a (meth) acryloyl group) can effectively contribute to the softening of the crosslinked structure formed by the reaction of the ethylenically unsaturated group. Conceivable. In some embodiments, among the ethylenically unsaturated groups contained in the molecule, 50% or more, more preferably 75% or more, for example, substantially 100% of the ethylenically unsaturated groups have an AO unit. Adjacently arranged photoreactive monomers (B) may be preferably employed.

As the photoreactive monomer (B), a compound having 2 to 10 ethylenically unsaturated groups in the molecule is preferable, and a compound having 2 to 8 ethylenically unsaturated groups in the molecule is more preferable, and the molecule is more preferable. Compounds having 2 to 6 ethylenically unsaturated groups within are more preferred. In some embodiments, the photoreactive monomer (B) may be a compound having 3 or more (typically 3-8, eg 3-6) ethylenically unsaturated groups in the molecule. it can. By incorporating a photoreactive monomer (B) having three or more ethylenically unsaturated groups in the molecule in the pressure-sensitive adhesive layer, the durability of adhesion of the pressure-sensitive adhesive layer to the adherend after curing is made efficient. It can be improved well (eg, even with a relatively small amount of photoreactive monomer (B)). This can be advantageous from the viewpoint of processability, handleability, and the like of the pressure-sensitive adhesive sheet disclosed herein. In some other embodiments, the photoreactive monomer (B) can be a compound having two ethylenically unsaturated groups in the molecule. Thereby, an adhesive sheet showing higher peel strength can be realized.

Examples of the photoreactive monomer (B) having three or more ethylenically unsaturated groups in the molecule include ethoxylated pentaerythritol tri (meth) acrylate, ethoxylated pentaerythritol tetra (meth) acrylate, and ethoxylated dipentaerythritol. Ethylene oxide (EO) -modified trimethylolpropanetri such as penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, trimethylolpropan trioxyethyl (meth) acrylate and trimethylolpropan polyoxyethyl (meth) acrylate Examples thereof include propylene oxide (PO) -modified trimethylol propanetri (meth) acrylates such as (meth) acrylates, trimethylolpropane trioxypropyl (meth) acrylates and trimethylolpropane polyoxypropyl (meth) acrylates. Not limited to. Examples of the photoreactive monomer (B) having two ethylenically unsaturated groups in the molecule include polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, EO-modified bisphenol A di (meth) acrylate, and EO. Examples thereof include, but are not limited to, modified bisphenol F di (meth) acrylate, PO modified bisphenol A di (meth) acrylate, and PO modified bisphenol F di (meth) acrylate.

The functional group equivalent of the compound used as the photoreactive monomer (B) (that is, the molecular weight per ethylenically unsaturated group of the compound) is not particularly limited and may be, for example, about 80 to 800. In some embodiments, as the photoreactive monomer (B), a compound having a molecular weight (functional group equivalent) of 250 or less per ethylenically unsaturated group can be preferably used. The functional group equivalent is preferably 250 or less, more preferably 225 or less. The functional group equivalent is determined by dividing the weight average molecular weight (Mw) of the photoreactive monomer (B) by the number of ethylenically unsaturated groups of the photoreactive monomer. According to the photoreactive monomer (B) having a smaller functional group equivalent, the durability of adhesion of the pressure-sensitive adhesive layer to the adherend after curing tends to be improved more efficiently. This makes it possible to suppress the amount of the photoreactive monomer (B) used to obtain the desired effect, which can be advantageous from the viewpoint of processability and handleability of the pressure-sensitive adhesive sheet. In some embodiments, the functional group equivalent of the photoreactive monomer (B) may be, for example, less than 200, less than 175, less than 150, or less than 145. Further, from the viewpoint of increasing the flexibility of cross-linking, the functional group equivalent of the photoreactive monomer (B) is usually preferably 100 or more, and preferably 110 or more. In some embodiments, the functional group equivalent may be 120 or greater, 125 or greater, or 130 or greater.
The weight average molecular weight of the photoreactive monomer (B) can be obtained as a standard polystyrene-equivalent value by, for example, a gel permeation chromatography (GPC) method. Further, as the weight average molecular weight of the photoreactive monomer (B), the weight average molecular weight calculated from the manufacturer's nominal value or the molecular structure may be adopted.

As the photoreactive monomer (B), a compound in which the number of AO units per ethylenically unsaturated group is, for example, 0.5 or more can be preferably used. The number of AO units per ethylenically unsaturated group can be determined by dividing the number of AO units contained in one molecule of the photoreactive monomer (B) by the number of ethylenically unsaturated groups. From the viewpoint of increasing the flexibility of cross-linking, in some embodiments, the number of AO units per ethylenically unsaturated group may be, for example, 0.65 or more, 0.75 or more, and 0.8. The above may be sufficient. Further, from the viewpoint of efficiently introducing a crosslinked structure having appropriate flexibility into the pressure-sensitive adhesive layer, in some embodiments, the photoreactive monomer (B) contains AO units per ethylenically unsaturated group. Compounds having a number of less than 3.5 are preferable, and compounds having a number of less than 3.0 are more preferable. From the viewpoint of obtaining higher cross-linking efficiency, the number of AO units per ethylenically unsaturated group may be less than 2.5, less than 2.0, or less than 1.5 in some embodiments. , 1.2 or less. The technique disclosed herein is a photoreactive monomer (B) in which the number of AO units per ethylenically unsaturated group is 0.8 or more and less than 1.2 (typically, about 1.0). It can be preferably carried out in the embodiment using the compound.

The molecular weight of the photoreactive monomer (B) is not particularly limited, and can be selected so as to preferably exert the desired effect. For example, as the photoreactive monomer (B), one having a weight average molecular weight (Mw) of about 2500 or less can be used. From the viewpoint of ease of preparation of the pressure-sensitive adhesive composition and the like, in some embodiments, the Mw of the photoreactive monomer (B) may be, for example, 2000 or less, 1500 or less, or 1000 or less. The Mw of the photoreactive monomer (B) is typically 200 or more. From the viewpoint of processability and handleability of the pressure-sensitive adhesive sheet, in some embodiments, the Mw of the photoreactive monomer (B) may be, for example, 230 or more, 300 or more, 350 or more, 450 or more. However, it may be 500 or more, or 550 or more.

In the pressure-sensitive adhesive sheet disclosed herein, the amount of the photoreactive monomer (B) contained in the pressure-sensitive adhesive layer is not particularly limited and can be appropriately set according to the desired performance. In some embodiments, the content of the photoreactive monomer (B) in the pressure-sensitive adhesive layer is, for example, 0.5 part by weight or more with respect to 100 parts by weight of the acrylic polymer (A) contained in the pressure-sensitive adhesive layer. Usually, 1 part by weight or more is suitable, 2 parts by weight or more, 3 parts by weight or more, or 4 parts by weight or more. As the content of the photoreactive monomer (B) increases, the adhesion durability of the pressure-sensitive adhesive layer to the adherend after photocuring tends to improve. The content of the photoreactive monomer (B) with respect to 100 parts by weight of the acrylic polymer (A) can be, for example, 30 parts by weight or less, and is usually 20 parts by weight from the viewpoint of processability of the adhesive sheet. It is appropriate to be less than, preferably less than 15 parts by weight. In some embodiments, the content of the photoreactive monomer (B) with respect to 100 parts by weight of the acrylic polymer (A) may be less than 10 parts by weight, for example, from the viewpoint of avoiding a decrease in peel strength due to excessive cross-linking. , Less than 8.0 parts by weight, or less than 6.0 parts by weight.

The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet disclosed herein contains at least a photoreactive monomer (B), so that an unreacted (unpolymerized) ethylenically unsaturated group is present in the pressure-sensitive adhesive layer. The functional group concentration of the pressure-sensitive adhesive layer, that is, the number of moles of ethylenically unsaturated groups per 100 g (phgp) of the acrylic polymer contained in the pressure-sensitive adhesive layer is not particularly limited. The functional group concentration may be, for example, about 25 mmol (phgp) or more, and may be about 30 mmol (phgp) or more. From the viewpoint of preferably exerting the effect of improving the adhesion durability by photocuring the pressure-sensitive adhesive layer, the functional group concentration is preferably about 32 mmol (phgp) or more, and is about 35 mmol (phgp) in some embodiments. It is more preferable that it is phgp) or more. The upper limit of the functional group concentration is not particularly limited. In some embodiments, the functional group concentration is 100 mmol (phgp) from the viewpoint of suppressing a decrease in peel strength due to excessive cross-linking and a decrease in processability due to an increase in the amount of the photoreactive monomer (B) used. ) Or less, preferably 80 mmol (phgp) or less, 70 mmol (phgp) or less, 55 mmol (phgp) or less, 45 mmol (phgp) or less, for example 40 mmol (phgp). It may be as follows.

In some aspects of the pressure-sensitive adhesive sheet disclosed herein, the photoreactive monomer (B) is preferably contained in the pressure-sensitive adhesive layer in free form. Such a pressure-sensitive adhesive layer can be suitably formed by using a pressure-sensitive adhesive composition containing the photoreactive monomer (B) in a free form. Here, the "free form" means that the photoreactive monomer (B) is not chemically bonded to another component (for example, the acrylic polymer (A)) contained in the pressure-sensitive adhesive layer or the pressure-sensitive adhesive composition. To say. The pressure-sensitive adhesive composition containing the photoreactive monomer (B) in a free form can be advantageous from the viewpoint of ease of preparation and suppression of gelation. In some other forms, the photoreactive monomer (B) is an acrylic polymer (eg, acrylic polymer (A)) contained in the pressure-sensitive adhesive layer or the pressure-sensitive adhesive composition from the viewpoint of improving the processability of the pressure-sensitive adhesive sheet. )) May be chemically bonded. The chemical bond is, for example, a functional group F1 other than the ethylenically unsaturated group that the photoreactive monomer (B) has in the molecule, and a functional group that the other component has in the molecule and is the functional group F1. It can be formed by reaction with a reactive functional group F2.

The pressure-sensitive adhesive layer has two or more ethylenically unsaturated groups in the molecule and does not correspond to the photoreactive monomer (B), as long as the effects obtained by the techniques disclosed herein are not significantly impaired. It may contain a seed or two or more kinds of monomers (C). Examples of such monomer (C) include compounds having two or more ethylenically unsaturated groups in the molecule and no AO building units; two or more ethylenically unsaturated groups in the molecule. A compound having an ethylenically unsaturated group having a molecular weight of more than 250 and having an AO unit; having two or more ethylenically unsaturated groups in the molecule and one ethylenically unsaturated group. Compounds with a per-molecular weight greater than 250 and no AO units; etc. are included. Specific examples of the compound corresponding to the monomer (C) include pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, and dipenta. Elythritol hexa (meth) acrylate, trimethylolpropane tri (meth) acrylate, ditrimethylol propanetetra (meth) acrylate, trimethylol ethanetri (meth) acrylate, tetramethylol methanetri (meth) acrylate, tris (2-hydroxyethyl) Isocyanurate di (meth) acrylate, tris (2-hydroxyethyl) isocyanurate tri (meth) acrylate, neopentyl glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate of hydroxypivalate, pentaerythritol di (meth) Includes, but is limited to, acrylate, allyl (meth) acrylate, vinyl (meth) acrylate, divinylbenzene, hydroquinone di (meth) acrylate, resorsindi (meth) acrylate, tricyclodecanedimethanol di (meth) acrylate, etc. Not done. The content of the monomer (C) in the pressure-sensitive adhesive layer may be, for example, 0.9 times or less of the content of the photoreactive monomer (B) on a weight basis, and is usually 0.5 times or less. Is appropriate, and may be 0.2 times or less, or 0.1 times or less. The pressure-sensitive adhesive sheet disclosed herein can be preferably implemented in a form in which the pressure-sensitive adhesive layer substantially does not contain the monomer (C). Here, substantially free of the monomer (C) means that the monomer (C) is not used at least intentionally, and for example, impurities or subcomponents in the material used for preparing the pressure-sensitive adhesive composition. As a result, it is acceptable that the compound corresponding to the monomer (C) is unintentionally mixed in a small amount.

(Acrylic oligomer)
The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet disclosed herein includes improved cohesive force, a surface adjacent to the pressure-sensitive adhesive layer (for example, the surface of a support on the pressure-sensitive adhesive sheet, the surface of an adherend to which the pressure-sensitive adhesive sheet is attached, and the like. From the viewpoint of improving the adhesiveness with (), an acrylic oligomer can be contained. The pressure-sensitive adhesive layer containing the acrylic oligomer can be preferably formed by using the pressure-sensitive adhesive composition containing the acrylic oligomer. As the acrylic oligomer, those having a higher Tg than the Tg of the acrylic polymer (A) described above can be preferably adopted.

The Tg of the acrylic oligomer is not particularly limited, and may be, for example, about 20 ° C. or higher and 300 ° C. or lower. The Tg may be, for example, about 30 ° C. or higher, about 40 ° C. or higher, about 60 ° C. or higher, about 80 ° C. or higher, or about 100 ° C. or higher. As the Tg of the acrylic oligomer increases, the effect of improving the cohesive force tends to increase in general. Further, from the viewpoint of anchoring property to the support, shock absorption, etc., the Tg of the acrylic oligomer may be, for example, about 250 ° C. or lower, about 200 ° C. or lower, about 180 ° C. or lower, or about 150 ° C. or lower. It may be. The Tg of the acrylic oligomer is a value calculated based on the Fox formula, like the Tg of the acrylic polymer (A).

The Mw of the acrylic oligomer is not particularly limited, and may be, for example, about 1000 or more, usually about 1500 or more, and may be about 2000 or more, or about 3000 or more. Further, the Mw of the acrylic oligomer may be, for example, less than about 30,000, usually less than about 10,000, and may be less than about 7,000 or less than 5,000. When Mw is within the above range, the effect of improving the cohesiveness of the pressure-sensitive adhesive layer and the adhesiveness with the adjacent surface is likely to be suitably exhibited. The Mw of the acrylic oligomer can be measured by gel permeation chromatography (GPC) and determined as a standard polystyrene-equivalent value. Specifically, for example, it can be measured using TSKgelGMH-H (20) × 2 as a column on HPLC8020 manufactured by Tosoh Co., Ltd. under the condition of a flow velocity of about 0.5 mL / min in a tetrahydrofuran solvent.

The monomer components constituting the acrylic oligomer include the above-mentioned various (meth) acrylic acid C _1-20 alkyl esters; the above-mentioned various alicyclic hydrocarbon group-containing (meth) acrylates; and the above-mentioned various aromatic hydrocarbons. Examples thereof include (meth) acrylate monomers containing a hydrogen group; (meth) acrylate obtained from a terpene compound derivative alcohol; and the like. These can be used alone or in combination of two or more.

Acrylic oligomers are alkyl (meth) acrylates in which alkyl groups such as isobutyl (meth) acrylate and t-butyl (meth) acrylate have a branched structure; alicyclic hydrocarbon group-containing (meth) acrylate and aromatic hydrocarbons. It is preferable to contain an acrylic monomer having a relatively bulky structure as a monomer unit, such as a group-containing (meth) acrylate; from the viewpoint of improving adhesiveness. Further, when ultraviolet rays are used when synthesizing an acrylic oligomer or when producing an adhesive layer, a monomer having a saturated hydrocarbon group at the ester terminal is preferable because it is unlikely to cause polymerization inhibition, for example, alkyl. Alkyl (meth) acrylates having a branched group or saturated alicyclic hydrocarbon group-containing (meth) acrylates can be preferably used.

The ratio of the (meth) acrylate monomer to all the monomer components constituting the acrylic oligomer is typically more than 50% by weight, preferably 60% by weight or more, more preferably 70% by weight or more (for example, 80% by weight). And more, 90% by weight or more). In a preferred embodiment, the acrylic oligomer has a monomer composition consisting substantially of only one or more (meth) acrylate monomers. When the monomer component contains an alicyclic hydrocarbon group-containing (meth) acrylate and a (meth) acrylic acid C _1-20 alkyl ester, their weight ratios are not particularly limited. In some embodiments, the weight ratio of the alicyclic hydrocarbon group-containing (meth) acrylate / (meth) acrylic acid C _1-20 alkyl ester is, for example, 10/90 or higher, 20/80 or higher, or 30/70 or higher. It can also be 90/10 or less, 80/20 or less, or 70/30 or less.

As a constituent monomer component of the acrylic oligomer, a functional group-containing monomer can be used, if necessary, in addition to the above (meth) acrylate monomer. Examples of the functional group-containing monomer include a monomer having a nitrogen atom-containing heterocycle such as N-vinyl-2-pyrrolidone and N-acryloylmorpholin; an amino group-containing monomer such as N, N-dimethylaminoethyl (meth) acrylate; N, Examples thereof include an amide group-containing monomer such as N-diethyl (meth) acrylamide; a carboxy group-containing monomer such as AA and MAA; and a hydroxyl group-containing monomer such as 2-hydroxyethyl (meth) acrylate. These functional group-containing monomers may be used alone or in combination of two or more. When a functional group-containing monomer is used, the ratio of the functional group-containing monomer to all the monomer components constituting the acrylic oligomer can be, for example, 1% by weight or more, 2% by weight or more, or 3% by weight or more, and also. For example, it can be 15% by weight or less, 10% by weight or less, or 7% by weight or less. The acrylic oligomer may be one in which a functional group-containing monomer is not used.

Suitable acrylic oligomers include, for example, dicyclopentanyl methacrylate (DCPMA), cyclohexyl methacrylate (CHMA), isobornyl methacrylate (IBXMA), isobornyl acrylate (IBXA), dicyclopentanyl acrylate (DCPA), and the like. In addition to 1-adamantyl methacrylate (ADAM) and 1-adamantyl acrylate (ADA) homopolymers, DCPMA and MMA copolymers, DCPMA and IBXMA copolymers, and ADA and methyl methacrylate (MMA) copolymer weights. Combined, a polymer of CHMA and isobutyl methacrylate (IBMA), a polymer of CHMA and IBXMA, a polymer of CHMA and acryloylmorpholin (ACMO), a polymer of CHMA and diethylacrylamide (DEAA), Examples thereof include a copolymer of CHMA and AA.

Acrylic oligomers can be formed by polymerizing their constituent monomer components. The polymerization method and the polymerization mode are not particularly limited, and various conventionally known polymerization methods (for example, solution polymerization, emulsion polymerization, bulk polymerization, photopolymerization, radiation polymerization, etc.) can be adopted in an appropriate manner. The types of polymerization initiators (for example, azo-based polymerization initiators) that can be used as needed are generally as illustrated for the synthesis of the acrylic polymer (A), and the amount of the polymerization initiator and the chain that is arbitrarily used. Since the amount of the transfer agent (for example, mercaptans) is appropriately set based on the common general knowledge so as to have a desired molecular weight, detailed description thereof will be omitted.

When the acrylic oligomer is contained in the pressure-sensitive adhesive layer or the pressure-sensitive adhesive composition, the content thereof can be, for example, 0.01 part by weight or more with respect to 100 parts by weight of the acrylic polymer (A), which is higher. From the viewpoint of obtaining the effect, it may be 0.05 parts by weight or more, 0.1 parts by weight or more, or 0.2 parts by weight or more. Further, from the viewpoint of compatibility with the acrylic polymer (A) and the like, the content of the acrylic oligomer with respect to 100 parts by weight of the acrylic polymer (A) is usually preferably less than 50 parts by weight, and is preferable. Is less than 30 parts by weight, more preferably 25 parts by weight or less, for example, 10 parts by weight or less, 5 parts by weight or less, or 1 part by weight or less.

The pressure-sensitive adhesive layer or pressure-sensitive adhesive composition of the pressure-sensitive adhesive sheet disclosed herein includes, if necessary, a pressure-imparting resin (for example, a rosin-based, petroleum-based, terpene-based, phenol-based, ketone-based, or other tack-imparting resin). Various additions common in the field of adhesives such as viscosity modifiers (for example, thickeners), leveling agents, plasticizers, fillers, colorants such as pigments and dyes, stabilizers, preservatives, anti-aging agents, etc. The agent may be included as any other optional ingredient. As for such various additives, conventionally known ones can be used by a conventional method and do not particularly characterize the present invention, and thus detailed description thereof will be omitted.
It should be noted that the technique disclosed herein can exhibit good adhesive strength without using the above-mentioned tackifier resin. Therefore, in some embodiments, the content of the tackifier resin in the pressure-sensitive adhesive layer or the pressure-sensitive adhesive composition is, for example, less than 10 parts by weight, or even 5 parts by weight, based on 100 parts by weight of the acrylic polymer (A). It can be less than a part by weight. The content of the tackifier resin may be less than 1 part by weight (for example, less than 0.5 parts by weight) or less than 0.1 parts by weight (0 parts by weight or more and less than 0.1 parts by weight). Good. The pressure-sensitive adhesive layer or pressure-sensitive adhesive composition may not contain a tackifier resin.

When the pressure-sensitive adhesive sheet disclosed herein is used for optical purposes, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet may have predetermined optical properties (for example, transparency). From the viewpoint of such optical properties, the amount of components other than the acrylic polymer (A) and the photoreactive monomer (B) in the pressure-sensitive adhesive layer (and thus the pressure-sensitive adhesive composition used to form the pressure-sensitive adhesive layer) is , Preferably restricted. In the technique disclosed herein, the amount of components other than the acrylic polymer (A) and the photoreactive monomer (B) in the pressure-sensitive adhesive layer is usually about 30% by weight or less, and about 15% by weight or less. This is appropriate, preferably about 12% by weight or less (for example, about 10% by weight or less). In the pressure-sensitive adhesive sheet according to one embodiment, the amount of the components other than the acrylic polymer (A) and the photoreactive monomer (B) in the pressure-sensitive adhesive layer may be about 5% by weight or less, and is about 3% by weight or less. It may be about 1.5% by weight or less (for example, about 1% by weight or less).

(Crosslinking agent)
A cross-linking agent may be used for the pressure-sensitive adhesive layer, if necessary. In the pressure-sensitive adhesive sheets disclosed herein, the cross-linking agent is typically included in the pressure-sensitive adhesive layer in the form after the cross-linking reaction. By using a cross-linking agent, the cohesive force of the pressure-sensitive adhesive layer before photo-curing can be appropriately adjusted. Further, by using the cross-linking agent and the photoreactive monomer (B) in combination, properties such as adhesion durability and peel strength of the pressure-sensitive adhesive layer after photocuring can be appropriately adjusted.

The type of the cross-linking agent is not particularly limited, and is selected from the conventionally known cross-linking agents so that the cross-linking agent exhibits an appropriate cross-linking function in the pressure-sensitive adhesive layer, for example, depending on the composition of the pressure-sensitive adhesive composition. be able to. Examples of the cross-linking agent that can be used include isocyanate-based cross-linking agents, epoxy-based cross-linking agents, oxazoline-based cross-linking agents, aziridine-based cross-linking agents, carbodiimide-based cross-linking agents, melamine-based cross-linking agents, urea-based cross-linking agents, metal alkoxide-based cross-linking agents, and metals. Examples thereof include a chelate-based cross-linking agent, a metal salt-based cross-linking agent, a hydrazine-based cross-linking agent, and an amine-based cross-linking agent. These can be used alone or in combination of two or more.

As the isocyanate-based cross-linking agent, a bifunctional or higher functional isocyanate compound can be used. For example, aromatic isocyanates such as tolylene diisocyanate, xylene diisocyanate, polymethylene polyphenyl diisocyanate, tris (p-isocyanatophenyl) thiophosphate, diphenylmethane diisocyanate; alicyclic isocyanates such as isophorone diisocyanate; aliphatic isocyanates such as hexamethylene diisocyanate. Isocyanate; etc. Commercially available products include trimethylolpropane / tolylene diisocyanate trimer adduct (manufactured by Toso Co., Ltd., trade name "Coronate L") and trimethylolpropane / hexamethylene diisocyanate trimester adduct (manufactured by Toso Co., Ltd., trade name "Coronate L"). Coronate HL "), isocyanurates of hexamethylene diisocyanate (manufactured by Toso Co., Ltd., trade name" Coronate HX "), trimethylolpropane / xylylene diisocyanate adduct (manufactured by Mitsui Chemicals Co., Ltd., trade name" Takenate D-110N "), etc. Can be exemplified with the isocyanate adduct of the above.

As the epoxy-based cross-linking agent, one having two or more epoxy groups in one molecule can be used without particular limitation. An epoxy-based cross-linking agent having 3 to 5 epoxy groups in one molecule is preferable. Specific examples of the epoxy-based cross-linking agent include N, N, N', N'-tetraglycidyl-m-xylene diamine, 1,3-bis (N, N-diglycidyl aminomethyl) cyclohexane, and 1,6-hexane. Examples thereof include diol diglycidyl ether, polyethylene glycol diglycidyl ether, and polyglycerol polyglycidyl ether. Commercially available epoxy cross-linking agents include Mitsubishi Gas Chemical Company's product names "TETRAD-X" and "TETRAD-C", DIC's product name "Epicron CR-5L", and Nagase ChemteX's products. Examples thereof include the name "Denacol EX-512" and the product name "TEPIC-G" manufactured by Nissan Chemical Industries, Ltd.

As the oxazoline-based cross-linking agent, those having one or more oxazoline groups in one molecule can be used without particular limitation.
Examples of the aziridine-based cross-linking agent include trimethylolpropane tris [3- (1-aziridinyl) propionate], trimethylolpropane tris [3- (1- (2-methyl) aziridinyl propionate)], and the like. Be done.
As the carbodiimide-based cross-linking agent, a low molecular weight compound or a high molecular weight compound having two or more carbodiimide groups can be used.

Peroxides may be used as the cross-linking agent in some embodiments. Peroxides include di (2-ethylhexyl) peroxydicarbonate, di (4-t-butylcyclohexyl) peroxydicarbonate, di-sec-butylperoxydicarbonate, and t-butylperoxyneodecanoate. , T-hexyl peroxypivalate, t-butylperoxypivalate, dilauroyl peroxide, di-n-octanoyl peroxide, 1,1,3,3-tetramethylbutylperoxyisobutyrate, di Examples thereof include benzoyl peroxide. Among these, examples of peroxides having particularly excellent cross-linking reaction efficiency include di (4-t-butylcyclohexyl) peroxydicarbonate, dilauroyl peroxide, and dibenzoyl peroxide. When a peroxide is used as the polymerization initiator, the peroxide remaining without being used in the polymerization reaction can be used in the crosslinking reaction. In that case, the residual amount of peroxide may be quantified, and if the ratio of peroxide is less than a predetermined amount, the peroxide may be added so as to be a predetermined amount, if necessary. The quantification of peroxide can be performed by the method described in Japanese Patent No. 4971517.

The amount used when a cross-linking agent is used (when two or more kinds of cross-linking agents are used, the total amount thereof) is not particularly limited. From the viewpoint of realizing a pressure-sensitive adhesive that exhibits a well-balanced adhesive property such as adhesive strength and cohesive power, the amount of the cross-linking agent used is usually about 5 parts by weight or less with respect to 100 parts by weight of the acrylic polymer (A). It may be 3 parts by weight or less, 2 parts by weight or less, 1 part by weight or less, or less than 1 part by weight. From the viewpoint of facilitating the effect of using the photoreactive monomer (B) in combination, in some embodiments, the cross-linking agent (for example, isocyanate-based cross-linking agent) with respect to 100 parts by weight of the acrylic polymer (A) is used. The amount used may be, for example, 0.50 parts by weight or less, 0.40 parts by weight or less, 0.30 parts by weight or less, or 0.20 parts by weight or less. The lower limit of the amount of the cross-linking agent used is not particularly limited, and may be more than 0 parts by weight with respect to 100 parts by weight of the acrylic polymer (A). In some embodiments, the amount of the cross-linking agent used can be, for example, 0.001 part by weight or more, 0.01 parts by weight or more, and 0, based on 100 parts by weight of the acrylic polymer (A). It may be 0.05 parts by weight or more, or 0.10 parts by weight or more.

A cross-linking catalyst may be used to allow the cross-linking reaction to proceed more effectively. Examples of the cross-linking catalyst include metal-based cross-linking catalysts such as tetra-n-butyl titanate, tetraisopropyl titanate, ferric nasem, butyl tin oxide, and dioctyl tin dilaurate. Of these, tin-based cross-linking catalysts such as dioctyl tin dilaurate are preferable. The amount of the cross-linking catalyst used is not particularly limited. The amount of the cross-linking catalyst used can be, for example, about 0.0001 parts by weight or more, about 0.001 parts by weight or more, about 0.005 parts by weight or more, etc. with respect to 100 parts by weight of the acrylic polymer (A). Further, it can be about 1 part by weight or less, about 0.1 part by weight or less, about 0.05 part by weight or less, and the like.

The pressure-sensitive adhesive composition used to form the pressure-sensitive adhesive layer can optionally contain a compound that causes keto-enol tautomerism as a cross-linking retarder. For example, in a pressure-sensitive adhesive composition containing an isocyanate-based cross-linking agent or a pressure-sensitive adhesive composition that can be used by blending an isocyanate-based cross-linking agent, a compound that causes keto-enol tautomerism can be preferably used. As a result, the effect of extending the pot life of the pressure-sensitive adhesive composition can be exhibited.
As the compound that causes keto-enol tautomerism, various β-dicarbonyl compounds can be used. Specific examples include β-diketones such as acetylacetone and 2,4-hexanedione; acetoacetate esters such as methyl acetoacetate and ethyl acetoacetate; propionyl acetates such as ethyl propionyl acetate; isobutylyl such as ethyl isobutylyl acetate. Acetic acid esters; malonic acid esters such as methyl malonate and ethyl malonate; and the like. Among them, acetylacetone and acetoacetic ester are preferable compounds. The compounds that cause keto-enol tautomerism can be used alone or in combination of two or more.
The amount of the compound that causes keto-enol tvariability may be, for example, 0.1 part by weight or more and 20 parts by weight or less, and usually 0.5 parts by weight, based on 100 parts by weight of the acrylic polymer (A). It is appropriate that the amount is 15 parts by weight or less, for example, 1 part by weight or more and 10 parts by weight or less, and 1 part by weight or more and 5 parts by weight or less.

(Water affinity)
The pressure-sensitive adhesive layer in the technique disclosed herein and the pressure-sensitive adhesive composition that can be used for forming the pressure-sensitive adhesive layer can contain a water-affinitive agent, if desired. By containing a water-affinitive agent in the pressure-sensitive adhesive layer, the peeling force can be effectively reduced by utilizing an aqueous liquid such as water. The reason is not particularly limited, but in general, the water-affinitive agent is unevenly distributed on the surface of the pressure-sensitive adhesive layer (for example, the pressure-sensitive adhesive layer formed from the solvent-type pressure-sensitive adhesive composition) due to having a hydrophilic region. It is considered that the adhesive layer is easy to use, thereby efficiently increasing the water affinity of the surface of the pressure-sensitive adhesive layer, and effectively reducing the peeling force when the pressure-sensitive adhesive layer comes into contact with water.

As the water-affinitive agent, one that is liquid at room temperature (about 25 ° C.) can be preferably used from the viewpoint of ease of preparation of the pressure-sensitive adhesive composition. The water affinity agent may be used alone or in combination of two or more.

In some embodiments, as the water affinity, at least one compound A selected from a surfactant and a compound having a polyoxyalkylene skeleton can be used. As the compound having a surfactant and a polyoxyalkylene skeleton, one or more of known surfactants and compounds having a polyoxyalkylene skeleton can be used without particular limitation. Needless to say, among the above-mentioned surfactants, there are compounds having a polyoxyalkylene skeleton, and vice versa.

As the surfactant that can be used as the compound A, known nonionic surfactants, anionic surfactants, cationic surfactants and the like can be used. Of these, nonionic surfactants are preferable. The surfactant may be used alone or in combination of two or more.

Examples of nonionic surfactants include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, and polyoxyethylene oleyl ether; polyoxyethylene octylphenyl ether, and poly. Polyoxyethylene alkylphenyl ether such as oxyethylene nonylphenyl ether; sorbitan fatty acid ester such as sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate; polyoxyethylene sorbitan monolaurate, polyoxyethylene Polyoxyethylene sorbitan such as sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan tristearate, polyoxyethylene sorbitan triisostearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan trioleate Examples thereof include fatty acid ester; polyoxyethylene glyceryl ether fatty acid ester; polyoxyelene-polyoxypropylene block copolymer; and the like. These nonionic surfactants can be used alone or in combination of two or more.

Examples of anionic surfactants include alkylbenzene sulfonates such as nonylbenzene sulfonate, dodecylbenzene sulfonate (eg sodium dodecylbenzene sulfonate); lauryl sulfate (eg sodium lauryl sulfate, ammonium lauryl sulfate), etc. Alkyl sulfate such as octadecyl sulfate; fatty acid salt; polyoxyethylene alkyl ether sulfate such as polyoxyethylene octadecyl ether sulfate and polyoxyethylene lauryl ether sulfate (for example, sodium polyoxyethylene alkyl ether sulfate), polyoxy Polyoxyethylene alkyl phenyl ether sulfate such as ethylene lauryl phenyl ether sulfate (for example, sodium polyoxyethylene alkyl phenyl ether sulfate, sodium polyoxyethylene alkyl phenyl ether sulfate, etc.), polyoxyethylene styrene phenyl ether sulfate, etc. Polyether sulfate; polyoxyethylene alkyl ether phosphate such as polyoxyethylene stearyl ether phosphate and polyoxyethylene lauryl ether phosphate; sodium salt and potassium salt of the above polyoxyethylene alkyl ether phosphate and the like. Polyoxyethylene alkyl ether phosphate ester salts; sulfosuccinates such as lauryl sulfosuccinate, polyoxyethylene lauryl sulfosuccinate (eg, sodium polyoxyethylene alkyl sulfosuccinate); polyoxyethylene alkyl ether acetate; etc. Can be mentioned. When the anionic surfactant forms a salt, the salt may be, for example, a metal salt such as a sodium salt, a potassium salt, a calcium salt or a magnesium salt (preferably a monovalent metal salt), an ammonium salt, an amine salt or the like. Can be. The anionic surfactant may be used alone or in combination of two or more.

In some embodiments, for example, an anionic surfactant having at least one of a -POH group, a -COH group and a -SOH group may be preferably used. Of these, a surfactant having a −POH group is preferable. Such surfactants typically contain a phosphoric acid ester structure, such as a phosphoric acid monoester (ROP (= O) (OH) ₂ ; where R is a monovalent organic group), a diester. ((RO) ₂ P (= O) OH; where R is the same or different monovalent organic group), a mixture containing both monoesters and diesters, and the like. A preferable example of a surfactant having a −POH group is a polyoxyethylene alkyl ether phosphate ester. The number of carbon atoms of the alkyl group in the polyoxyethylene alkyl ether phosphoric acid ester may be, for example, 6 to 20, may be 8 to 20, may be 10 to 20, may be 12 to 20, or may be 14 to 20.

Examples of cationic surfactants include polyether amines such as polyoxyethylene laurylamine and polyoxyethylene stearylamine. The cationic surfactant may be used alone or in combination of two or more.

Examples of the compound having a polyoxyalkylene skeleton that can be used as compound A include polyalkylene glycols such as polyethylene glycol (PEG) and polypropylene glycol (PPG); polyethers containing polyoxyethylene units, and polyoxypropylene units. Compounds containing polyethers, oxyethylene units and oxypropylene units (the sequences of these units may be random or block-like); derivatives thereof; and the like can be used. Further, among the above-mentioned surfactants, compounds having a polyoxyalkylene skeleton can also be used. These can be used alone or in combination of two or more. Among them, it is preferable to use a compound containing a polyoxyethylene skeleton (also referred to as a polyoxyethylene segment), and PEG is more preferable.

The molecular weight (chemical formula amount) of the compound having a polyoxyalkylene skeleton (for example, polyethylene glycol) is not particularly limited, and is preferably less than 1000, and is about 600 or less (for example, from the viewpoint of adhesive composition preparability). It is preferably 500 or less). The lower limit of the molecular weight of the compound having a polyoxyalkylene skeleton (for example, polyethylene glycol) is not particularly limited, and a compound having a molecular weight of about 100 or more (for example, about 200 or more, further about 300 or more) is preferably used.

Other examples of water-affinitive agents include water-soluble polymers such as polyvinyl alcohol, polyvinylpyrrolidone, and polyacrylic acid. The water-soluble polymer may be used alone or in combination of two or more. In the technique disclosed herein, as the water affinity agent, one or more of Compound A may be used, or one or more of water-soluble polymers may be used, and these may be used in combination. You may.

The HLB of a water-affinitive (typically a surfactant) is not particularly limited, for example, 3 or more, about 6 or more is suitable, and 8 or more (for example, 9 or more) can be used. In a preferred embodiment, the water affinity has an HLB of 10 or greater. As a result, water peelability tends to be preferably exhibited. The HLB is more preferably 11 or more, still more preferably 12 or more, and particularly preferably 13 or more (for example, 14 or more). Water affinity agent having an HLB within the above range, SP value of 23.0 (MJ / m ^{3) 1/2} or less (e.g. 18.0~23.0 (MJ / m ³⁾⁾ acrylic polymer (A ) Is included in the pressure-sensitive adhesive composition (and thus the pressure-sensitive adhesive layer), so that water removability can be more effectively exhibited. The upper limit of the HLB is 20 or less, for example, 18 or less, or 16 or less (for example, 15 or less).

In addition, HLB in this specification is a Hydrophile-Lipophile Balance by Griffin, which is a value indicating the degree of affinity of a surfactant with water or oil, and the ratio of hydrophilicity to lipophilicity is between 0 and 20. It is expressed by the numerical value of. The definition of HLB is W. C. Griffin: J. Soc. Cosmetic Chemists, 1,311 (1949), Koshimitsu Takahashi, Yoshiro Namba, Motoo Koike, Masao Kobayashi, "Surfactant Handbook", 3rd Edition, Kogaku Shosha Publishing, November 25, 1972, p179- As described in 182 and the like. The water-affinitive agent having the above-mentioned HLB can be selected based on the common general technical knowledge of those skilled in the art by referring to the above-mentioned references as necessary.

The pressure-sensitive adhesive layer containing the water-affinitive agent is typically formed from the pressure-sensitive adhesive composition containing the water-affinitive agent. The form of the pressure-sensitive adhesive composition is not particularly limited, and for example, any of the above-mentioned water-dispersible pressure-sensitive adhesive composition, solvent-type pressure-sensitive adhesive composition, hot-melt type pressure-sensitive adhesive composition, and the like may be used. In some embodiments, the pressure-sensitive adhesive layer containing the water-affinitive is preferably a pressure-sensitive adhesive layer formed from a solvent-based pressure-sensitive adhesive composition. As a preferred embodiment of the pressure-sensitive adhesive sheet disclosed herein, a pressure-sensitive adhesive layer formed of a solvent-based pressure-sensitive adhesive composition containing an acrylic polymer (A), a photoreactive monomer (B), and a water-affinitive agent. An embodiment including the above is exemplified.

In the pressure-sensitive adhesive sheets disclosed herein, it is preferred that the water-affinitive agent is typically contained in the pressure-sensitive adhesive layer in free form. The pressure-sensitive adhesive layer containing the water-affinitive agent in the free form can be suitably formed by using the pressure-sensitive adhesive composition containing the water-affinitive agent in the free form. In some embodiments, the aqueous affinity agent may preferably be a compound having no ethylenically unsaturated group. Since such a water-affinitive agent is still contained in the pressure-sensitive adhesive layer after curing in a free state, the water-removability of the water-affinitive agent can be suitably exhibited.

The amount of the water-affinitive agent used is not particularly limited, and can be set so that the effect of using the water-affinitive agent is appropriately exhibited. In some embodiments, the content of the water-affinitive agent can be, for example, 0.001 part by weight or more, and usually 0.01 part by weight or more, per 100 parts by weight of the acrylic polymer (A). It is suitable, and may be 0.03 parts by weight or more, 0.07 parts by weight or more, or 0.1 parts by weight or more. In some preferred embodiments, the content of the aqueous affinity agent may be, for example, 0.2 parts by weight or more with respect to 100 parts by weight of the acrylic polymer (A), and is 0.5 from the viewpoint of obtaining a higher effect. It may be 10 parts by weight or more, 1.0 part by weight or more, or 1.5 parts by weight or more. Further, from the viewpoint of suppressing excessive water diffusion (water absorption) into the pressure-sensitive adhesive layer, in some embodiments, the amount of the water-affinitive agent used is, for example, 100 parts by weight of the acrylic polymer (A). It may be 20 parts by weight or less, usually 10 parts by weight or less, preferably 5 parts by weight or less, and may be 3 parts by weight or less. It is preferable that the content of the water-affinitive agent is not too large from the viewpoint of improving the transparency of the pressure-sensitive adhesive layer. For example, in some embodiments, the content of the water affinity with respect to 100 parts by weight of the acrylic polymer (A) may be less than 2 parts by weight, less than 1 part by weight, less than 0.7 parts by weight, 0. It may be less than 5.5 parts by weight. A water affinity agent having an HLB of 10 or more tends to exhibit good water desorption even when used in a small amount.

(Silane coupling agent)
The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet disclosed herein may contain a silane coupling agent, if desired. By using a silane coupling agent, the peel strength of the pressure-sensitive adhesive sheet from an adherend (for example, a glass plate) can be improved. The pressure-sensitive adhesive layer containing the silane coupling agent can be suitably formed by using the pressure-sensitive adhesive composition containing the silane coupling agent. In such a pressure-sensitive adhesive composition, the silane coupling agent is preferably contained in the pressure-sensitive adhesive composition in a free form from the viewpoint of suppressing gelation and the like. Also, in some embodiments, the silane coupling agent is preferably contained in the pressure-sensitive adhesive layer in free form. The silane coupling agent contained in the pressure-sensitive adhesive layer in such a form can effectively contribute to the improvement of the peeling force. The term "free form" as used herein means that the silane coupling agent is not chemically bonded to the pressure-sensitive adhesive composition or other components contained in the pressure-sensitive adhesive layer.

Examples of the silane coupling agent include silicon compounds having an epoxy structure such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, and 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane; Amino group-containing silicon compounds such as 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) 3-aminopropylmethyldimethoxysilane; 3-chloro Propyltrimethoxysilane; (meth) acrylic group-containing silane coupling agents such as acetoacetyl group-containing trimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane; 3-isocyanoxide propyltriethoxysilane Examples thereof include silane coupling agents containing isocyanate groups. In some embodiments, the above effects can be more preferably exerted by adopting a silane coupling agent having a trialkoxysilyl group. Among them, 3-glycidoxypropyltrimethoxysilane and acetoacetyl group-containing trimethoxysilane are exemplified as preferable silane coupling agents.

When a silane coupling agent is used, the amount used can be set so as to obtain a desired effect, and is not particularly limited. In some embodiments, the amount of the silane coupling agent used may be, for example, 0.001 part by weight or more with respect to 100 parts by weight of the acrylic polymer (A), and 0.005 from the viewpoint of obtaining a higher effect. It may be 0.01 parts by weight or more, 0.015 parts by weight or more, or 0.015 parts by weight or more. Further, from the viewpoint of improving the adhesion to the adherend, in some embodiments, the amount of the silane coupling agent used is, for example, 3 parts by weight or less with respect to 100 parts by weight of the acrylic polymer (A). It may be 1 part by weight or less, or 0.5 part by weight or less.
The technique disclosed herein does not substantially use a silane coupling agent (for example, the amount of the silane coupling agent used per 100 parts by weight of the acrylic polymer (A) is 0.0005 parts by weight or less. It may be 0 parts by weight.) It can also be preferably carried out in an embodiment. As a result, the water peelability of the adhesive sheet is improved (for example, the water peeling force is lowered, the water peeling adhesive force is lowered), the storage stability of the adhesive sheet is improved (for example, the quality change due to storage is suppressed), and the adhesive is adhered. Effects such as improvement of storage stability of the agent composition (for example, suppression of gelation) can be realized.

(Photopolymerization initiator)
The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet disclosed herein may contain a photopolymerization initiator, if necessary, for the purpose of improving or imparting photocurability. As the photopolymerization initiator, the ketal-based photopolymerization initiator, the acetophenone-based photopolymerization initiator, and the benzoin ether-based photopolymerization initiator are the same as those exemplified as those that can be used for the synthesis of the acrylic polymer (A). Agent, acylphosphine oxide-based photopolymerization initiator, α-ketor-based photopolymerization initiator, aromatic sulfonyl chloride-based photopolymerization initiator, photoactive oxime-based photopolymerization initiator, benzoin-based photopolymerization initiator, benzyl-based photopolymerization An initiator, a benzophenone-based photopolymerization initiator, a thioxanthone-based photopolymerization initiator, or the like can be used. The photopolymerization initiator may be used alone or in combination of two or more.

Specific examples of the ketal-based photopolymerization initiator include 2,2-dimethoxy-1,2-diphenylethane-1-one and the like.
Specific examples of the acetophenone-based photopolymerization initiator include 1-hydroxycyclohexyl-phenyl-ketone, 4-phenoxydichloroacetophenone, 4-t-butyl-dichloroacetophenone, 1- [4- (2-hydroxyethoxy) -phenyl]. -2-Hydroxy-2-methyl-1-propane-1-one, 2-hydroxy-2-methyl-1-phenyl-propane-1-one, methoxyacetophenone and the like are included.
Specific examples of the benzoin ether-based photopolymerization initiator include benzoin ethers such as benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether and benzoin isobutyl ether, and substituted benzoin ethers such as anisole methyl ether.
Specific examples of acylphosphine oxide-based photopolymerization initiators include bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide and bis (2,4,6-trimethylbenzoyl) -2,4-di-n-butoxy. Includes phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide and the like.
Specific examples of the α-ketol-based photopolymerization initiator include 2-methyl-2-hydroxypropiophenone, 1- [4- (2-hydroxyethyl) phenyl] -2-methylpropan-1-one, and the like. Is done. Specific examples of the aromatic sulfonyl chloride-based photopolymerization initiator include 2-naphthalene sulfonyl chloride and the like. Specific examples of the photoactive oxime-based photopolymerization initiator include 1-phenyl-1,1-propanedione-2- (o-ethoxycarbonyl) -oxime and the like. Specific examples of the benzoin-based photopolymerization initiator include benzoin and the like. Specific examples of the benzyl-based photopolymerization initiator include benzyl and the like.
Specific examples of the benzophenone-based photopolymerization initiator include benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, α-hydroxycyclohexylphenyl ketone and the like.
Specific examples of the thioxanthone-based photopolymerization initiator include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, and isopropylthioxanthone. , 2,4-Diisopropylthioxanthone, dodecylthioxanthone and the like.

The content of the photopolymerization initiator in the pressure-sensitive adhesive layer is not particularly limited, and can be set so as to appropriately exert the desired effect. In some embodiments, the content of the photopolymerization initiator can be, for example, approximately 0.005 parts by weight or more, typically 0.01 parts by weight or more, relative to 100 parts by weight of the acrylic polymer (A). It is appropriate that the amount is 0.05 parts by weight or more, 0.10 parts by weight or more, 0.15 parts by weight or more, or 0.20 parts by weight or more. By increasing the content of the photopolymerization initiator, the photocurability of the pressure-sensitive adhesive layer is improved. The content of the photopolymerization initiator with respect to 100 parts by weight of the acrylic polymer (A) is usually preferably 5 parts by weight or less, preferably 2 parts by weight or less, and 1 part by weight or less. It may be 0.7 parts by weight or less, or 0.5 parts by weight or less. Not too much content of the photopolymerization initiator can be advantageous from the viewpoint of improving the storage stability (for example, stability against photodegradation) of the pressure-sensitive adhesive sheet.

The pressure-sensitive adhesive layer containing the photopolymerization initiator can be typically formed by using a pressure-sensitive adhesive composition containing the photopolymerization initiator (for example, a solvent-type pressure-sensitive adhesive composition). The pressure-sensitive adhesive composition containing the photopolymerization initiator can be prepared, for example, by mixing other components used in the composition with the photopolymerization initiator. Further, when the pressure-sensitive adhesive composition is prepared using the acrylic polymer (A) synthesized (photopolymerized) in the presence of the photopolymerization initiator, it is used when synthesizing the acrylic polymer (A). The residue (unreacted product) of the photopolymerization initiator may be used as a part or all of the photopolymerization initiator contained in the pressure-sensitive adhesive layer. The same applies to the case where an acrylic oligomer synthesized as necessary in the presence of a photopolymerization initiator is used. From the viewpoint of ease of production control, the pressure-sensitive adhesive layer disclosed herein is preferably formed by using a pressure-sensitive adhesive composition prepared by newly adding the above-mentioned amount of the photopolymerization initiator to other components. Can be done.

<Formation of adhesive layer>
The pressure-sensitive adhesive layer constituting the pressure-sensitive adhesive sheet disclosed herein can be a cured layer of a pressure-sensitive adhesive composition containing the corresponding component. That is, the pressure-sensitive adhesive layer is subjected to drying (for example, heat-drying), cross-linking (for example, cross-linking by the reaction of the above-mentioned cross-linking agent), cooling, etc. after applying (for example, coating) the pressure-sensitive adhesive composition to an appropriate surface. It can be formed by appropriately performing a curing treatment. When performing two or more types of curing treatments, these can be performed simultaneously or in stages.

The application of the pressure-sensitive adhesive composition can be carried out using a conventional coater such as a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, or a spray coater. In the pressure-sensitive adhesive sheet having a support, as a method of providing the pressure-sensitive adhesive layer on the support, a direct method of directly applying the pressure-sensitive adhesive composition to the support to form the pressure-sensitive adhesive layer may be used, and peeling may be used. A transfer method may be used in which the pressure-sensitive adhesive layer formed on the surface is transferred to the support.

The thickness of the pressure-sensitive adhesive layer is not particularly limited, and may be, for example, about 3 μm to 2000 μm. From the viewpoint of adhesion to the adherend such as step followability, in some embodiments, the thickness of the pressure-sensitive adhesive layer may be, for example, 5 μm or more, preferably 10 μm or more, preferably 20 μm or more, and more. It is preferably 30 μm or more. The thickness of the pressure-sensitive adhesive layer may be 50 μm or more, more than 50 μm, 70 μm or more, 100 μm or more, or 120 μm or more. Further, from the viewpoint of preventing the generation of adhesive residue due to the cohesive failure of the pressure-sensitive adhesive layer, the thickness of the pressure-sensitive adhesive layer may be, for example, 1000 μm or less, 700 μm or less, or 500 μm or less in some embodiments. , 300 μm or less, and further 200 μm or less or 170 μm or less. The technique disclosed herein can also be preferably carried out in the form of a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer thickness of 130 μm or less, 90 μm or less, 60 μm or less, or 40 μm or less. In the pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer having two or more layers, the thickness of the pressure-sensitive adhesive layer is the thickness from the pressure-sensitive adhesive surface attached to the adherend to the surface opposite to the pressure-sensitive adhesive surface. Say.

<Characteristics of adhesive layer>
In the pressure-sensitive adhesive sheet disclosed herein, the shear storage elastic modulus (that is, the initial elastic modulus) of the pressure-sensitive adhesive layer at 85 ° C. is not particularly limited. The initial elastic modulus of the pressure-sensitive adhesive layer may be, for example, less than 50 kPa, less than 45 kPa, or less than 40 kPa. From the viewpoint of enhancing the followability to the surface shape of the adherend, in some embodiments, the initial elastic modulus of the pressure-sensitive adhesive layer may be, for example, less than 35 kPa, preferably less than 30 kPa, and may be less than 27 kPa. It may be less than 25 kPa. Further, in some embodiments, the initial elastic modulus of the pressure-sensitive adhesive layer may be, for example, more than 5 kPa, more than 10 kPa, more than 15 kPa, more than 18 kPa, or more than 20 kPa. The fact that the initial elastic modulus is not too low is a viewpoint of workability when the adhesive sheet is used and workability when the adhesive sheet is used (for example, workability when the adhesive surface is separated from the peelable surface and exposed). Can be advantageous from.
The initial elastic modulus of the pressure-sensitive adhesive layer can be measured by the method described in Examples described later. The initial elastic coefficient of the pressure-sensitive adhesive layer is determined by the composition of the pressure-sensitive adhesive layer (for example, the composition of Mw of the acrylic polymer (A) and its monomer component, the type and content of the photoreactive monomer (B), the cross-linking agent, and the acrylic-based). It can be adjusted by the presence or absence of each optional component such as an oligomer and a water-affinitive agent, and the type and content of the optional component when used).

In the pressure-sensitive adhesive sheet disclosed herein, the shear storage elastic modulus (that is, the elastic modulus after curing) of the pressure-sensitive adhesive layer at 85 ° C. after photo-curing is not particularly limited. From the viewpoint of preventing the generation of adhesive residue due to cohesive failure of the pressure-sensitive adhesive layer, it is usually appropriate that the elastic modulus after curing of the pressure-sensitive adhesive layer is 25 kPa or more. From the viewpoint of improving the adhesion durability to the adherend (particularly, the adherend that easily generates outgas such as a polarizing plate), the elastic modulus after curing of the pressure-sensitive adhesive layer is 30 kPa or more in some embodiments. It is appropriate that it is 33 kPa or more, more preferably 37 kPa or more, 40 kPa or more, 45 kPa or more, 50 kPa or more, or 55 kPa or more. The photoreactive monomer (B) contained in the pressure-sensitive adhesive layer forms a crosslinked structure having appropriate flexibility by photocuring. As a result, the pressure-sensitive adhesive layer containing the photoreactive monomer (B) tends to suppress a decrease in peel strength with respect to the adherend even if the elastic modulus after curing is relatively high. Therefore, according to the pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer containing the photoreactive monomer (B), the pressure-sensitive adhesive layer is photo-cured after being attached to the adherend, thereby achieving good adhesion durability and good peel strength. Can be compatible with. The elastic modulus after curing of the pressure-sensitive adhesive layer may be, for example, 200 kPa or less, 150 kPa or less, or 120 kPa or less. In some embodiments, the elastic modulus after curing of the pressure-sensitive adhesive layer is 100 kPa or less, from the viewpoint of making it easy to achieve a good balance between adhesion durability to the adherend and other properties (for example, peel strength). It is advantageous, preferably 80 kPa or less, 70 kPa or less, or 65 kPa or less. According to the pressure-sensitive adhesive sheet disclosed herein, even if the elastic modulus of the pressure-sensitive adhesive layer after curing is less than 60 kPa, good adhesion durability to the adherend and high peel strength can be achieved in a well-balanced manner after photo-curing. .. In some embodiments, the post-curing elastic modulus of the pressure-sensitive adhesive layer may be, for example, less than 55 kPa, less than 50 kPa, or even less than 45 kPa. As the elastic modulus of the pressure-sensitive adhesive layer decreases after curing, the peel strength with respect to the adherend tends to generally improve.
The elastic modulus after curing of the pressure-sensitive adhesive layer can be measured by the method described in Examples described later. The elastic modulus after curing of the pressure-sensitive adhesive layer includes the initial elastic modulus of the pressure-sensitive adhesive layer, the structure of the photoreactive monomer (B) contained in the pressure-sensitive adhesive layer, the functional group equivalent, Mw, and the content in the pressure-sensitive adhesive layer. It can be adjusted by the functional concentration of the pressure-sensitive adhesive layer and the like.

<Support>
The pressure-sensitive adhesive sheet according to some aspects may be in the form of a pressure-sensitive adhesive sheet with a support including a support bonded to the pressure-sensitive adhesive layer. The material of the support is not particularly limited, and can be appropriately selected depending on the purpose and mode of use of the adhesive sheet. Non-limiting examples of supports that can be used include polyolefin films mainly composed of polyolefins such as polypropylene and ethylene-propylene copolymers, polyester films mainly composed of polyesters such as polyethylene terephthalate and polybutylene terephthalate, and the like. Plastic film such as polyvinyl chloride film containing polyvinyl chloride as the main component; foam sheet made of foam such as polyurethane foam, polyethylene foam, polychloroprene foam; various fibrous substances (natural fibers such as hemp and cotton, Woven fabrics and non-woven fabrics made of synthetic fibers such as polyester and vinylon, semi-synthetic fibers such as acetate, etc.) alone or by blending; papers such as Japanese paper, high-quality paper, kraft paper, crepe paper; aluminum foil, copper Metallic foil such as foil; and the like. The support may be a composite structure of these. Examples of such a support having a composite structure include a support having a structure in which a metal foil and the plastic film are laminated, a plastic sheet reinforced with an inorganic fiber such as glass cloth, and the like.

As the support of the pressure-sensitive adhesive sheet disclosed herein, various films (hereinafter, also referred to as support films) can be preferably used. The support film may be a porous film such as a foam film or a non-woven sheet, or may be a non-porous film, and the porous layer and the non-porous layer are laminated. It may be a film having a structure. In some embodiments, as the support film, a film containing an independently shape-maintainable (self-supporting or independent) resin film as a base film can be preferably used. As used herein, the term "resin film" means a resin film (of voidless) having a non-porous structure and typically containing substantially no bubbles. Therefore, the resin film is a concept that is distinguished from a foam film and a non-woven fabric. The resin film may have a single-layer structure or a multi-layer structure having two or more layers (for example, a three-layer structure).

Examples of the resin material constituting the resin film include polycycloolefin derived from a monomer having an aliphatic ring structure such as polyester, polyolefin, and norbornene structure, nylon 6, nylon 66, and polyamide (PA) such as partially aromatic polyamide. , Polyamide (PI), Polyamideimide (PAI), Polyether ether ketone (PEEK), Polyether sulfone (PES), Polyphenylene sulfide (PPS), Polycarbonate (PC), Polyurethane (PU), Ethylene-vinyl acetate copolymer (EVA), polystyrene, polyvinyl chloride, polyvinylidene chloride, fluororesin such as polytetrafluoroethylene (PTFE), acrylic resin such as polymethylmethacrylate, cellulose-based polymer such as diacetylcellulose and triacetylcellulose, vinyl butyral polymer. , Arilate-based polymer, polyoxymethylene-based polymer, epoxy-based polymer and other resins can be used. The resin film may be formed by using a resin material containing one kind of such a resin alone, or may be formed by using a resin material in which two or more kinds are blended. May be good. The resin film may be unstretched or stretched (for example, uniaxially stretched or biaxially stretched).

Preferable examples of the resin material constituting the resin film include polyester-based resin, PPS resin, and polyolefin-based resin. Here, the polyester-based resin refers to a resin containing polyester in a proportion of more than 50% by weight. Similarly, the PPS resin refers to a resin containing PPS in a proportion of more than 50% by weight, and the polyolefin-based resin refers to a resin containing polyolefin in a proportion of more than 50% by weight.

As the polyester-based resin, a polyester-based resin containing a polyester obtained by polycondensing a dicarboxylic acid and a diol as a main component is typically used. Specific examples of the polyester resin include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polybutylene naphthalate and the like.

As the polyolefin resin, one kind of polyolefin can be used alone, or two or more kinds of polyolefins can be used in combination. The polyolefin can be, for example, a homopolymer of an α-olefin, a copolymer of two or more kinds of α-olefins, a copolymer of one kind or two or more kinds of α-olefins and another vinyl monomer, or the like. Specific examples include ethylene-propylene copolymers such as polyethylene (PE), polypropylene (PP), poly-1-butene, poly-4-methyl-1-pentene, and ethylene propylene rubber (EPR), and ethylene-propylene-. Examples thereof include butene copolymers, ethylene-butene copolymers, ethylene-vinyl alcohol copolymers, ethylene-ethyl acrylate copolymers and the like. Both low density (LD) polyolefins and high density (HD) polyolefins can be used. Examples of polyolefin resin films include unstretched polypropylene (CPP) film, biaxially stretched polypropylene (OPP) film, low density polyethylene (LDPE) film, linear low density polyethylene (LLDPE) film, medium density polyethylene (MDPE). Examples thereof include a film, a high-density polyethylene (HDPE) film, a polyethylene (PE) film in which two or more types of polyethylene (PE) are blended, and a PP / PE blend film in which polypropylene (PP) and polyethylene (PE) are blended.

Specific examples of the resin film that can be preferably used as the support include PET film, PEN film, PPS film, PEEK film, CPP film and OPP film. Preferred examples from the viewpoint of strength include PET film, PEN film, PPS film and PEEK film. A PET film is mentioned as a preferable example from the viewpoint of availability, dimensional stability, optical characteristics and the like.

Known additives such as light stabilizers, antioxidants, antistatic agents, colorants (dye, pigment, etc.), fillers, slip agents, antiblocking agents, etc. shall be added to the resin film, if necessary. Can be done. The blending amount of the additive is not particularly limited, and can be appropriately set according to the use of the pressure-sensitive adhesive sheet and the like.

The method for producing the resin film is not particularly limited. For example, conventionally known general resin film molding methods such as extrusion molding, inflation molding, T die casting molding, and calender roll molding can be appropriately adopted.

The support may be substantially composed of such a resin film. Alternatively, the support may include an auxiliary layer in addition to the resin film. Examples of the auxiliary layer include an optical property adjusting layer (for example, a colored layer, an antireflection layer), a printing layer or a laminating layer for imparting a desired appearance to a support or an adhesive sheet, an antistatic layer, and an undercoat layer. , A surface treatment layer such as a release layer. Further, the support material may be an optical member (for example, an optical film) described later.

The thickness of the support is not particularly limited, and can be selected according to the purpose of use, the mode of use, and the like of the adhesive sheet. The thickness of the support may be, for example, 1000 μm or less, 500 μm or less, 100 μm or less, 70 μm or less, 50 μm or less, 25 μm or less, 10 μm or less, or 5 μm or less. As the thickness of the support becomes smaller, the flexibility of the adhesive sheet and the ability to follow the surface shape of the adherend tend to improve. Further, from the viewpoint of handleability, workability and the like, the thickness of the support may be, for example, 2 μm or more, and may be 5 μm or more or 10 μm or more. In some embodiments, the thickness of the support may be, for example, 20 μm or greater, 35 μm or greater, or 55 μm or greater.

Corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, undercoating agent (primer) application, antistatic treatment, if necessary, on the surface of the support on the side bonded to the adhesive layer. A conventionally known surface treatment such as the above may be applied. Such a surface treatment may be a treatment for improving the adhesion between the support and the pressure-sensitive adhesive layer, in other words, the anchoring property of the pressure-sensitive adhesive layer on the support. The composition of the primer is not particularly limited, and can be appropriately selected from known ones. The thickness of the undercoat layer is not particularly limited, but is usually about 0.01 μm to 1 μm, preferably about 0.1 μm to 1 μm.

On the surface of the support opposite to the side bonded to the adhesive layer (hereinafter, also referred to as the back surface), if necessary, a peeling treatment, an adhesive or adhesive improving treatment, an antistatic treatment, etc. Conventionally known surface treatment may be applied. For example, by surface-treating the back surface of the support with a peeling agent, the unwinding force of the adhesive sheet wound in a roll shape can be reduced. As the stripping agent, a silicone-based stripping agent, a long-chain alkyl-based stripping agent, an olefin-based stripping agent, a fluorine-based stripping agent, a fatty acid amide-based stripping agent, molybdenum sulfide, silica powder, or the like can be used. ..

<Additional adhesive layer>
The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet disclosed herein is not limited to the single-layer structure as shown in FIGS. For example, the pressure-sensitive adhesive sheet disclosed herein has two or more layers (typically, a pressure-sensitive adhesive layer containing an acrylic polymer (A) and a photoreactive monomer (B)) (for example, 2 to 2). 5 layers) It may have a laminated multi-layer structure. The composition of each layer constituting the multi-layered pressure-sensitive adhesive layer may be the same or different.
The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet disclosed herein is one or more layers of the above-mentioned pressure-sensitive adhesive layer (typically, a pressure-sensitive adhesive layer containing an acrylic polymer (A) and a photoreactive monomer (B)). In addition, one or more pressure-sensitive adhesive layers (additional pressure-sensitive adhesive layers) having the same or different composition may be further provided. Each layer of one or more such additionally arranged pressure-sensitive adhesive layers (additional pressure-sensitive adhesive layer) may or may not contain the photoreactive monomer (B) independently. The additional pressure-sensitive adhesive layer not containing the photoreactive monomer (B) uses the photoreactive monomer (B) and contains the result of the reaction of the ethylenically unsaturated group of the photoreactive monomer (B). It may be a pressure-sensitive adhesive layer, or it may be an additional pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive composition that does not use the photoreactive monomer (B). In addition, each layer of the additional adhesive layer is independently, for example, an acrylic adhesive, a rubber adhesive (natural rubber, synthetic rubber, a mixture of these, etc.), a silicone adhesive, and a polyester adhesive. A pressure-sensitive adhesive composed of one or more types of pressure-sensitive adhesives selected from various known pressure-sensitive adhesives such as agents, urethane-based pressure-sensitive adhesives, polyether-based pressure-sensitive adhesives, polyamide-based pressure-sensitive adhesives, and fluorine-based pressure-sensitive adhesives. Can be a layer. From the viewpoint of transparency, weather resistance, and the like, an acrylic pressure-sensitive adhesive may be preferably adopted as a constituent material of the additional pressure-sensitive adhesive layer in some embodiments. Regarding other matters of the additional pressure-sensitive adhesive layer, the same structure as the above-mentioned pressure-sensitive adhesive layer (the pressure-sensitive adhesive layer containing the acrylic polymer (A) and the photoreactive monomer (B)) can be adopted, or Since an appropriate configuration can be adopted according to the application and purpose based on known or commonly used techniques and common general knowledge, detailed description thereof will be omitted here.

When the pressure-sensitive adhesive layer has a multi-layer structure (laminated structure) of two or more layers, the pressure-sensitive adhesive layer having such a multi-layer structure can be produced by laminating the pressure-sensitive adhesive layers of the respective layers formed in advance. Alternatively, the pressure-sensitive adhesive composition may be applied onto the first pressure-sensitive adhesive layer formed in advance, and the pressure-sensitive adhesive composition may be cured to form a second pressure-sensitive adhesive layer.

<Characteristics of adhesive sheet>
The pressure-sensitive adhesive sheet disclosed herein is a peel strength measured by peeling a pressure-sensitive adhesive sheet obtained by photo-curing an adhesive layer from the adherend by a conventional method (dry method) after being attached to the adherend, more specifically. Specifically, the peel strength FN (hereinafter, also referred to as “normal peel strength”) measured by the method described in Examples described later may be, for example, about 2.5 N / 10 mm or more, and is usually about 3. It is appropriate that it is 0 N / 10 mm or more. From the viewpoint of improving the joining reliability, the peel strength FN is preferably, for example, about 3.5 N / 10 mm or more, and more preferably about 4.5 N / 10 mm or more. For example, in the pressure-sensitive adhesive sheet according to one aspect, the peel strength FN may be, for example, about 5.0 N / 10 mm or more, about 5.5 N / 10 mm or more, or about 6.5 N / 10 mm or more, and may be about 6.5 N / 10 mm or more. It may be 7.5 N / 10 mm or more. The pressure-sensitive adhesive sheet disclosed herein can also be implemented in an embodiment in which the peel strength FN is about 9N / 10 mm or more, about 10N / 10mm or more, about 11N / 10mm or more, about 12N / 10mm or more, or about 13N / 10mm or more. Such a strong adhesive force can be preferably realized by using, for example, a silane coupling agent. The upper limit of the peel strength FN is not particularly limited, and may be, for example, 25N / 10mm or less, 20N / 10mm or less, 15N / 10mm or less, or 10N / 10mm or less.

In some aspects of the pressure-sensitive adhesive sheet disclosed herein, the pressure-sensitive adhesive sheet is a pressure-sensitive adhesive sheet obtained by photo-curing an adhesive layer after being attached to an adherend by a water peeling method (wet method) from the adherend. The peeling force measured by peeling, more specifically, the water peeling force Fw measured by the method described in Examples described later may be less than about 2.5 N / 10 mm. From the viewpoint of reworkability using water peeling, the water peeling force Fw may be, for example, about 2.0 N / 10 mm or less, less than 1.5 N / 10 mm, less than 1.0 N / 10 mm, and 0. It may be less than .8N / 10mm.

In some aspects of the pressure-sensitive adhesive sheet disclosed herein, the pressure-sensitive adhesive sheet is based on the normal peel strength FN and the water peeling force FW and has the following formula:
Water peeling adhesive strength reduction rate [%] = (1- (FW / FN)) × 100;
The rate of decrease in water peeling adhesive strength calculated by the above can be, for example, about 30% or more.

Water peeling A pressure-sensitive adhesive sheet having a high rate of decrease in adhesive strength can be peeled off using an aqueous liquid such as water, whereby the load applied to the adherend at the time of peeling can be remarkably reduced. For example, a small amount of an aqueous liquid is supplied to the adherend to which the adhesive sheet is attached, and the aqueous liquid is allowed to enter the interface between the adhesive sheet and the adherend from one end of the adhesive sheet to trigger peeling. By peeling off the adhesive sheet after making it, the peeling strength of the adhesive sheet from the adherend can be significantly reduced. Utilizing this property, it is possible to achieve both the performance of suppressing the displacement and floating of the adhesive sheet attached to the adherend and the good reworkability. In some embodiments, the rate of decrease in water peeling adhesive strength is preferably 50% or more, preferably 60% or more, for example, 70% or more, 75% or more, and 80%. It may be more than or equal to 85% or more. The rate of decrease in water peeling adhesive strength is 100% or less in principle, and typically less than 100%.

In the technique disclosed herein, the haze value of the pressure-sensitive adhesive sheet is preferably about 10% or less, and can be about 5% or less (for example, about 3% or less). The haze value is preferably 1.0% or less. Such a highly transparent pressure-sensitive adhesive sheet is suitable for optical applications that require high light transmission. The haze value of the pressure-sensitive adhesive sheet may be less than 1.0%, less than 0.7%, or 0.5% or less (for example, 0 to 0.5%). These haze values for the pressure-sensitive adhesive sheet can also be preferably applied to the haze values of the pressure-sensitive adhesive layer in the techniques disclosed herein.

Here, the "haze value" refers to the ratio of diffuse transmitted light to total transmitted light when the measurement target is irradiated with visible light. Also called cloudy value. The haze value can be expressed by the following equation.
Th [%] = Td / Tt × 100
In the above formula, Th is a haze value [%], Td is a scattered light transmittance, and Tt is a total light transmittance.
The haze value can be measured using a haze meter (for example, "MR-100" manufactured by Murakami Color Technology Laboratory). The haze value can be adjusted by selecting, for example, the composition and thickness of the pressure-sensitive adhesive layer.

<Manufacturing method of laminate>
The pressure-sensitive adhesive sheet disclosed herein can be preferably used in an embodiment in which the pressure-sensitive adhesive layer is photo-cured after being bonded to the adherend and then adhered to the adherend. By adhering the adhesive sheet to the adherend, an adherend on which the adhesive sheets are laminated is formed. By photocuring the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet, a laminate containing the pressure-sensitive adhesive sheet with the cured pressure-sensitive adhesive layer and the adherend can be obtained. Therefore, according to this specification, one of the pressure-sensitive adhesive sheets disclosed herein is attached to an adherend, and the pressure-sensitive adhesive sheet is irradiated with ultraviolet rays to photo-cure the pressure-sensitive adhesive layer, in that order. A method for producing a laminate including the above is provided.
When the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet used in the mode of photo-curing after being attached to an adherend has a multi-layer structure, the photo-curing pressure-sensitive adhesive layer is a part of the layers included in the multi-layer structure (for example, It may be one layer) or all layers.

<Use>
The pressure-sensitive adhesive sheet disclosed herein can be used for fixing, joining, molding, decorating, protecting, supporting and the like of members constituting various products. The material constituting at least the surface of the member is, for example, glass such as an alkaline glass plate or non-alkali glass; a metal material such as a resin film, stainless steel (SUS) or aluminum; an acrylic resin, an ABS resin, a polycarbonate resin or a polystyrene resin. Etc. Resin material; etc. The member may be, for example, a member constituting various portable devices (portable devices), automobiles, home appliances, and the like. Further, in the above member, the surface to which the adhesive sheet is attached is an acrylic type, a polyester type, an alkyd type, a melamine type, a urethane type, an acid epoxy crosslinked type, or a composite type thereof (for example, an acrylic melamine type or an alkyd melamine type). ) Or the like, or a surface coated with a zinc-plated steel plate or the like. Further, the member may be any support film (for example, a resin film) exemplified as a material that can be used for the support. The pressure-sensitive adhesive sheet disclosed herein can be, for example, a component of a member with a pressure-sensitive adhesive sheet in which such a member is bonded to at least one surface of the pressure-sensitive adhesive layer.

In such a member with an adhesive sheet, the surface of the member in contact with the adhesive layer (hereinafter, also referred to as a joint surface) has a contact angle with distilled water of, for example, 60 degrees or less, preferably 50 degrees or less. It can be a surface that exhibits hydrophilicity. In some embodiments, the contact angle of the joint surface may be, for example, 45 degrees or less, 40 degrees or less, 35 degrees or less, or 30 degrees or less. When the contact angle of the joint surface becomes smaller, water tends to get wet and spread along the joint surface, and the water peelability of the adhesive sheet tends to be improved. This is preferable from the viewpoint of improving reworkability when the pressure-sensitive adhesive sheet is attached to the joint surface to produce a member with the pressure-sensitive adhesive sheet. If the contact angle of the joint surface is at least one of the above angles at the time of bonding the adhesive sheets (for example, 30 minutes before bonding), the rework is due to the contact angle being equal to or less than the predetermined angle. The effect of improving sex can be exhibited. The lower limit of the contact angle is 0 degrees in principle. In some embodiments, the contact angle of the joint surface may be more than 0 degrees, 1 degree or more, 3 degrees or more, or 5 degrees or more. The contact angle of the joint surface of the member is measured in the same manner as the contact angle of the alkaline glass plate described above.

The joint surface of the member may be hydrophilized in order to reduce the contact angle with distilled water. Examples of the hydrophilic treatment include treatments that contribute to the improvement of hydrophilicity, such as corona treatment, plasma treatment, and hydrophilic coating treatment for providing a hydrophilic coating layer. The apparatus and treatment conditions used for the corona treatment and the plasma treatment can be set so as to obtain a joint surface showing a desired contact angle based on conventionally known techniques. The hydrophilic coating layer can be formed by appropriately selecting a known coating agent capable of obtaining a joint surface showing a desired contact angle and using it by a conventional method. The thickness of the hydrophilic coating layer may be, for example, 0.01 μm or more, 0.05 μm or more, 0.1 μm or more, 10 μm or less, 5 μm or less, or 2 μm or less. Good.

An example of a preferred application is an optical application. More specifically, it is disclosed herein as, for example, an optical adhesive sheet used for bonding optical members (for bonding optical members), manufacturing products using the above optical members (optical products), and the like. The adhesive sheet to be used can be preferably used.

The optical member is a member having optical characteristics (for example, polarization, light refraction, light scattering, light reflectivity, light transmission, light absorption, photodiffraction, light turning property, visibility, etc.). Say. The optical member is not particularly limited as long as it has optical characteristics, but is used, for example, as a member constituting a device (optical device) such as a display device (image display device) or an input device, or a member thereof. Examples include polarizing plates, wavelength plates, retardation plates, optical compensation films, brightness improving films, light guide plates, reflective films, antireflection films, hard coat (HC) films, shock absorbing films, antifouling films, and the like. Photochromic film, light control film, transparent conductive film (ITO film), design film, decorative film, surface protection plate, prism, lens, color filter, transparent substrate, and members in which these are laminated (collectively referred to as these). (Sometimes referred to as "functional film") and the like. The above-mentioned "plate" and "film" shall include a plate-like, a film-like, a sheet-like form, respectively, and for example, the "polarizing film" shall include a "polarizing plate", a "polarizing sheet" and the like. ..

Examples of the display device include a liquid crystal display device, an organic EL (electroluminescence) display device, a PDP (plasma display panel), electronic paper, and the like. Further, examples of the input device include a touch panel and the like.

The optical member is not particularly limited, and examples thereof include a member made of glass, acrylic resin, polycarbonate, polyethylene terephthalate, a metal thin film, or the like (for example, a sheet-shaped, film-shaped, or plate-shaped member). The "optical member" in this specification also includes a member (design film, decorative film, surface protective film, etc.) that plays a role of decoration and protection while maintaining the visibility of the display device and the input device.

The mode in which the optical members are bonded using the pressure-sensitive adhesive sheet disclosed herein is not particularly limited, and examples thereof include (1) a mode in which the optical members are bonded to each other via the pressure-sensitive adhesive sheet disclosed here, and (2). ) The optical member may be attached to a member other than the optical member via the pressure-sensitive adhesive sheet disclosed herein, or (3) the pressure-sensitive adhesive sheet disclosed here includes the optical member. The adhesive sheet may be attached to an optical member or a member other than the optical member. In the aspect of (3) above, the pressure-sensitive adhesive sheet including the optical member may be, for example, a pressure-sensitive adhesive sheet in which the support is an optical member (for example, an optical film). As described above, the pressure-sensitive adhesive sheet including the optical member as the support can also be grasped as a pressure-sensitive optical member (for example, a pressure-sensitive optical film). Further, when the pressure-sensitive adhesive sheet disclosed here is a type of pressure-sensitive adhesive sheet having a support and the above-mentioned functional film is used as the above-mentioned support, the pressure-sensitive adhesive sheet disclosed here is a functional film. It can also be grasped as a "adhesive type functional film" having an adhesive layer disclosed here on at least one side.

<Peeling method>
According to this specification, a method for peeling an adhesive sheet attached to an adherend is provided. In the peeling method, the aqueous liquid follows the movement of the peeling front in a state where the aqueous liquid is present at the interface between the adherend and the adhesive sheet in the peeling front of the adhesive sheet from the adherend. Includes a water peeling step of peeling the adhesive sheet from the adherend while advancing the entry into the interface. Here, the peeling front refers to a portion where the pressure-sensitive adhesive sheet begins to separate from the adherend when the peeling of the pressure-sensitive adhesive sheet from the adherend is advanced. According to the water peeling step, the adhesive sheet can be peeled from the adherend by effectively utilizing the aqueous liquid. As the aqueous liquid, water or a mixed solvent containing water as a main component and containing a small amount of additives as necessary can be used. As the solvent other than water constituting the mixed solvent, a lower alcohol (for example, ethyl alcohol) or a lower ketone (for example, acetone) that can be uniformly mixed with water can be used. As the additive, a known surfactant or the like can be used. From the viewpoint of avoiding contamination of the adherend, an aqueous liquid containing substantially no additive may be preferably used in some embodiments. From the viewpoint of environmental hygiene, it is particularly preferable to use water as the aqueous liquid. The water is not particularly limited, and for example, distilled water, ion-exchanged water, tap water, or the like can be used in consideration of the purity and availability required according to the application.

In some embodiments, the peeling method supplies an aqueous liquid onto the adherend near the outer edge of the pressure-sensitive adhesive sheet attached to the adherend, and the aqueous liquid is fed from the outer edge of the pressure-sensitive adhesive sheet to the pressure-sensitive adhesive sheet. After entering the interface with the adherend, the adhesive sheet is peeled off without supplying new water (that is, using only the aqueous liquid supplied on the adherend before the start of peeling). It can be preferably carried out in such a manner. In some other embodiments, in the peeling method, a part of the adhesive sheet attached to the adherend (typically, a part connected to the outer edge of the adhesive sheet) floats from the adherend. In this state, the aqueous liquid is supplied to the portion where the remaining pressure-sensitive adhesive sheet begins to separate from the adherend, and the peeling of the pressure-sensitive adhesive sheet is allowed to proceed without supplying new water. If the water that enters the interface between the adhesive sheet and the adherend is depleted in the middle of the water peeling step following the movement of the peeling front, it may be intermittent or intermittent after the start of the water peeling step. Additional water may be supplied continuously. For example, when the adherend has water absorption, or when the aqueous liquid tends to remain on the surface or adhesive surface of the adherend after peeling, a mode in which water is additionally supplied after the start of the water peeling step is preferably adopted. obtain.

The amount of the aqueous liquid supplied before the start of peeling is not particularly limited as long as the amount of the aqueous liquid can be introduced into the interface between the pressure-sensitive adhesive sheet and the adherend. The amount of the aqueous liquid may be, for example, 5 μL or more, usually 10 μL or more, and may be 20 μL or more. Further, there is no particular limitation on the upper limit of the amount of the aqueous liquid. In some embodiments, from the viewpoint of improving workability, the amount of the aqueous liquid may be, for example, 10 mL or less, 5 mL or less, 1 mL or less, 0.5 mL or less, 0.1 mL or less. It may be 0.05 mL or less. By reducing the amount of the aqueous liquid, the operation of removing the aqueous liquid by drying, wiping, or the like after the pressure-sensitive adhesive sheet is peeled off can be omitted or simplified.

At the start of peeling, the operation of allowing the aqueous liquid to enter the interface between the adhesive sheet and the adherend from the outer edge of the adhesive sheet is, for example, to bring the tip of a jig such as a cutter knife or a needle to the interface at the outer edge of the adhesive sheet. Insertion, scratching the outer edge of the adhesive sheet with a hook or claw to lift it, attaching a strong adhesive tape or suction cup to the back surface near the outer edge of the adhesive sheet and lifting the edge of the adhesive sheet, etc. It can be carried out. By forcibly allowing the aqueous liquid to enter the interface from the outer edge of the pressure-sensitive adhesive sheet in this way, it is possible to efficiently form a state in which the water-based liquid exists at the interface between the adherend and the pressure-sensitive adhesive sheet. In addition, good water peeling property after creating a trigger for peeling by forcibly entering an aqueous liquid into the interface and high water resistance reliability when such an operation is not performed are preferably compatible. Can be done. The operation for triggering the peeling is intended to be a part of the adhesive sheet attached to the adherend (typically, a part connected to the outer edge of the adhesive sheet) before supplying the aqueous liquid. It can also be used as an operation to make it float from the adherend.

The pressure-sensitive adhesive sheet to be peeled off by the peeling method includes a pressure-sensitive adhesive layer, and at least the surface of the pressure-sensitive adhesive layer on the adherend side contains the acrylic polymer (A) and the photoreactive monomer (B) described above. It is preferably composed of the surface of the pressure-sensitive adhesive layer. The pressure-sensitive adhesive sheet is preferably any of the pressure-sensitive adhesive sheets disclosed herein, for example. Therefore, the peeling method is suitable as a peeling method for any of the pressure-sensitive adhesive sheets disclosed herein.

The water stripping step according to some embodiments can be preferably carried out in a mode in which the peeling front is moved at a speed of 10 mm / min or more. Moving the peeling front at a speed of 10 mm / min or more corresponds to peeling the adhesive sheet at a tensile speed of 20 mm / min or more, for example, under the condition of a peeling angle of 180 degrees. The speed at which the peeling front is moved may be, for example, 50 mm / min or more, 150 mm / min or more, 300 mm / min or more, or 500 mm / min or more. According to the peeling method disclosed herein, by peeling the pressure-sensitive adhesive sheet from the adherend while advancing the entry of the aqueous liquid into the interface, even such a relatively fast peeling speed is good. Can exhibit excellent water peelability. The upper limit of the speed at which the peeling front is moved is not particularly limited. The speed at which the peeling front is moved can be, for example, 1000 mm / min or less.

The peeling method disclosed herein is carried out, for example, in such a manner that the peeling area of the pressure-sensitive adhesive sheet per 10 μL of the volume of the aqueous liquid (for example, water) used in the method is, for example, 50 cm ² or more, preferably 100 cm ² or more. be able to.

The peeling method disclosed herein can be preferably applied to peeling an adhesive sheet attached to a non-water-absorbing smooth surface such as a glass plate, a metal plate, a resin plate or the like. Further, the peeling method disclosed herein can be preferably used as a method for peeling the pressure-sensitive adhesive sheet from any of the above-mentioned optical members. Above all, it is suitable as a method for peeling off the adhesive sheet attached to a glass plate such as alkaline glass or non-alkali glass.

The matters disclosed in this specification include the following.
(1) An adhesive sheet having an adhesive layer.
The pressure-sensitive adhesive layer contains an acrylic polymer (A) and a photoreactive monomer (B).
The pressure-sensitive adhesive sheet, wherein the photoreactive monomer (B) is a compound B having two or more ethylenically unsaturated groups and an oxyalkylene structural unit in the molecule.
(2) The pressure-sensitive adhesive sheet according to (1) above, wherein the compound B has a molecular weight of 250 or less per ethylenically unsaturated group contained in the compound B.
(3) The pressure-sensitive adhesive sheet according to (1) or (2) above, wherein the pressure-sensitive adhesive layer contains 35 mmol or more of an ethylenically unsaturated group per 100 g of the acrylic polymer.
(4) The content of the photoreactive monomer (B) in the pressure-sensitive adhesive layer is more than 0 parts by weight and less than 20 parts by weight with respect to 100 parts by weight of the acrylic polymer. The adhesive sheet according to any one of 3).
(5) The pressure-sensitive adhesive sheet according to any one of (1) to (4) above, wherein the shear storage elastic modulus of the pressure-sensitive adhesive layer at 85 ° C. after photo-curing is 30 kPa or more.
(6) The pressure-sensitive adhesive sheet according to any one of (1) to (5) above, wherein the shear storage elastic modulus of the pressure-sensitive adhesive layer at 85 ° C. after photo-curing is 65 kPa or less.
(7) The pressure-sensitive adhesive sheet according to any one of (1) to (6) above, wherein the shear storage elastic modulus of the pressure-sensitive adhesive layer at 85 ° C. is less than 30 kPa.
(8) The adhesive sheet according to any one of (1) to (7) above, wherein the peel strength measured by the following procedure is 5.0 N / 10 mm or more.
[Peeling strength measurement procedure]
The surface of the pressure-sensitive adhesive layer is pressure-bonded to a glass plate by reciprocating a 2 kg rubber roller once, autoclaving (50 ° C., 0.5 MPa, 15 minutes), and then the integrated light amount of 3000 mJ / cm from the glass plate side. The pressure-sensitive adhesive layer is photo-cured by irradiating with the ultraviolet rays of No. ² , and then the peeling strength at the time of peeling from the glass plate is measured under the conditions of a tensile speed of 300 mm / min and a peeling angle of 180 degrees in an atmosphere of 25 ° C. ..
(9) The pressure-sensitive adhesive sheet according to any one of (1) to (8) above, wherein the thickness of the pressure-sensitive adhesive layer is 10 μm or more and 200 μm or less.
(10) The adhesive sheet according to any one of (1) to (9) above, which is configured as a supportless double-sided adhesive sheet.

（一般式（１）中、Ｒ¹は２価の有機基である。）；
で表わされるＮ−ビニル環状アミド、および（メタ）アクリルアミドからなる群から選択される１種または２種以上のモノマーである、上記（２２）に記載の粘着剤組成物。
（２４） さらに剥離力上昇剤を含む、上記（１１）〜（２３）のいずれかに記載の粘着剤組成物。
（２５） 上記剥離力上昇剤は、アルコキシシリル基を有する化合物である、上記（２４）に記載の粘着剤組成物。
（２６） 上記（１）〜（１０）のいずれかの粘着シートの作製に用いられる、上記（１１）〜（２５）のいずれかに記載の粘着剤組成物。 (11) Containing an acrylic polymer (A) and a photoreactive monomer (B),
The pressure-sensitive adhesive composition, wherein the photoreactive monomer (B) is a compound B having two or more ethylenically unsaturated groups and an oxyalkylene structural unit in the molecule.
(12) The pressure-sensitive adhesive composition according to (11) above, further comprising a water-affinitive agent.
(13) The pressure-sensitive adhesive composition according to (12) above, wherein the water-affinitive agent is at least one compound A selected from a surfactant and a compound having a polyoxyalkylene skeleton.
(14) The pressure-sensitive adhesive composition according to (12) or (13) above, wherein the water-affinitive agent is a nonionic surfactant.
(15) The pressure-sensitive adhesive composition according to any one of (12) to (14) above, wherein the water-affinitive agent has an HLB of 10 or more.
(16) The pressure-sensitive adhesive composition according to any one of (12) to (15) above, wherein the content of the water-affinitive agent is less than 1 part by weight with respect to 100 parts by weight of the acrylic polymer (A). ..
(17) The pressure-sensitive adhesive composition according to any one of (11) to (16) above, which is a solvent-type pressure-sensitive adhesive composition.
(18) The pressure-sensitive adhesive composition according to any one of (11) to (17) above, wherein the compound B has a molecular weight of 250 or less per ethylenically unsaturated group contained in the compound B.
(19) The pressure-sensitive adhesive composition according to any one of (11) to (18) above, which contains 35 mmol or more of ethylenically unsaturated groups per 100 g of the acrylic polymer.
(20) Any of the above (11) to (19), wherein the content of the photoreactive monomer (B) is more than 0 parts by weight and less than 20 parts by weight with respect to 100 parts by weight of the acrylic polymer. The pressure-sensitive adhesive composition according to.
(21) Any of the above (11) to (20), wherein the number of the oxyalkylene structural units contained in the photoreactive monomer (B) is less than 2 per the ethylenically unsaturated group contained in the compound. The pressure-sensitive adhesive composition described in Crab.
(22) The monomer component forming the acrylic polymer (A) is
A (meth) acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms at the ester terminal,
Monomers with nitrogen atoms and
The pressure-sensitive adhesive composition according to any one of (11) to (21) above.
(23) The monomer having a nitrogen atom has the general formula (1):

(In the general formula (1), R ¹ is a divalent organic group.);
The pressure-sensitive adhesive composition according to (22) above, which is one or more monomers selected from the group consisting of N-vinyl cyclic amide represented by (2) and (meth) acrylamide.
(24) The pressure-sensitive adhesive composition according to any one of (11) to (23) above, further comprising a peeling force increasing agent.
(25) The pressure-sensitive adhesive composition according to (24) above, wherein the peeling force increasing agent is a compound having an alkoxysilyl group.
(26) The pressure-sensitive adhesive composition according to any one of (11) to (25) above, which is used for producing the pressure-sensitive adhesive sheet according to any one of (1) to (10) above.

(27) An adhesive sheet having an adhesive layer composed of the adhesive composition according to any one of (11) to (25) above.
(28) A member with an adhesive sheet, which comprises the adhesive sheet according to any one of (1) to (10) and (27), and a member bonded to the one surface of the adhesive layer.
(29) The member with an adhesive sheet according to (28) above, wherein the member is an optical member.

(30) A method of peeling an adhesive sheet attached to an adherend.
In the state where the aqueous liquid is present at the interface between the adherend and the adhesive sheet in the peeling front of the adhesive sheet from the adherend, the aqueous liquid follows the movement of the peeling front to the interface. A peeling method comprising a water peeling step of peeling the adhesive sheet from the adherend while advancing the approach.
(31) The peeling method according to (30), wherein the adhesive sheet is the adhesive sheet according to any one of (1) to (10) and (27).
(32) The peeling method according to (30) or (31) above, wherein in the water peeling step, the peeling front is moved at a speed of 10 mm / min or more.

(33) The adhesive sheet according to any one of (1) to (10) and (27) above is attached to the adherend, and
By irradiating the adhesive sheet with ultraviolet rays to photo-curing the adhesive layer,
A method for producing a laminate, which comprises the above in this order.
(34) A step of peeling the adhesive sheet from the adherend by any of the peeling methods (30) to (32), and
A step of attaching an adhesive sheet different from the peeled adhesive sheet to the adherend from which the adhesive sheet has been peeled off, and
The production method according to (33) above, further comprising.
(35) The production method according to (34) above, wherein the step of peeling off the pressure-sensitive adhesive sheet is performed after the pressure-sensitive adhesive layer is photocured.
(36) The production method according to (34) above, wherein the step of peeling off the pressure-sensitive adhesive sheet is performed before the pressure-sensitive adhesive layer is photocured.

Hereinafter, some examples of the present invention will be described, but the present invention is not intended to be limited to those shown in such examples. In the following description, "part" and "%" are based on weight unless otherwise specified.

<Preparation of adhesive composition>
(Examples 1 to 4, Examples 7 to 11)
In a reaction vessel equipped with a cooling tube, a nitrogen introduction tube, a thermometer and a stirrer, 64.5 parts of n-butyl acrylate (BA), 6 parts of cyclohexyl acrylate (CHA), and N-vinyl-2-pyrrolidone (N-vinyl-2-pyrrolidone) as monomer components. NVP) 9.6 parts, isostearyl acrylate (iSTA) 5 parts and 4-hydroxybutyl acrylate (4HBA) 14.9 parts, α-thioglycerol 0.07 parts as a chain transfer agent, ethyl acetate 122 parts as a polymerization solvent. By adding 0.2 parts of 2,2'-azobisisobutyronitrile (AIBN) as a charge and thermal polymerization initiator and performing solution polymerization in a nitrogen atmosphere, an acrylic polymer having an Mw of 600,000 is contained. A solution was obtained.

In the solution obtained above, per 100 parts of the monomer component used for the preparation of the solution, the photoreactive monomer of the type and amount shown in Table 1 and 1-hydroxycyclohexyl-phenyl-ketone (IGM Regins) as a photopolymerization initiator. Made by the company, trade name: Omnirad 184) 0.22 parts, solidified isocyanate-based cross-linking agent (monomer propane / xylylene diisocyanate adduct (manufactured by Mitsui Chemicals, trade name: Takenate D-110N, solid content concentration 75%) 0.16 parts on a minute basis, 0.011 parts of dioctyltin dilaurate (manufactured by Tokyo Fine Chemicals, trade name: Envirizer OL-1) as a cross-linking accelerator, 3.33 parts of acetylacetone as a cross-linking retarder, acrylic oligomer 0. Add 4 parts and 0.3 part of nonionic surfactant A (polyoxyethylene sorbitan monolaurate, HLB13.3, trade name: Leodor TW-L106, manufactured by Kao Co., Ltd.) as a water-affinitive agent and mix uniformly. Then, the solvent-type pressure-sensitive adhesive composition according to each example was prepared.

As the acrylic oligomer, one synthesized by the following method was used.
[Synthesis of acrylic oligomers]
100 parts of toluene, 60 parts of dicyclopentanyl methacrylate (DCPMA) (trade name: FA-513M, manufactured by Hitachi Chemical Co., Ltd.), 40 parts of methyl methacrylate (MMA), and 3.5 parts of α-thioglycerol as a chain transfer agent. Was put into a four-necked flask. Then, after stirring at 70 ° C. under a nitrogen atmosphere for 1 hour, 0.2 part of AIBN was added as a thermal polymerization initiator, and the mixture was reacted at 70 ° C. for 2 hours and then at 80 ° C. for 2 hours. Then, the reaction solution was put into a temperature atmosphere of 130 ° C., and toluene, the chain transfer agent, and the unreacted monomer were dried and removed to obtain a solid acrylic oligomer. The Tg of this acrylic oligomer was 144 ° C. and the Mw was 4300.

(Examples 5 and 6)
The solvent-based pressure-sensitive adhesive compositions according to Examples 5 and 6 were prepared in the same manner as in the preparation of the pressure-sensitive adhesive compositions of Examples 1 and 2, except that the water-affinitive agent (the nonionic surfactant A) was not used. ..

<Making an adhesive sheet>
Two release films (MRF # 38, manufactured by Mitsubishi Plastics) having a thickness of 38 μm in which one side of the polyester film is a release surface were prepared. The solvent-based pressure-sensitive adhesive composition according to each example prepared above was applied to the peeled surface of the first peeling film, dried at 60 ° C. for 3 minutes, and then dried at 120 ° C. for 3 minutes to obtain light having a thickness of 150 μm. A curable pressure-sensitive adhesive layer (support-less double-sided pressure-sensitive adhesive sheet) was formed. The peeling surface of the second release film was attached to this pressure-sensitive adhesive layer to protect it. In this way, a laminated sheet having a structure in which the first release film, the supportless double-sided adhesive sheet, and the second release film are laminated in this order was obtained.

<Measurement and evaluation>
The obtained adhesive sheet was measured and evaluated as follows.
(1) Measurement of Initial Elastic Modulus A pressure-sensitive adhesive layer laminate having a thickness of about 1.5 mm was prepared by removing the release liner from the above-mentioned laminated sheet and superimposing the pressure-sensitive adhesive layers. A sample punched into a disk shape with a diameter of 7.9 mm is sandwiched between parallel plates, and a viscoelasticity tester (ARES, manufactured by Leometrics) is used to apply shear strain at a frequency of 1 Hz in the temperature range of -70 to 150 ° C. Dynamic viscoelasticity was measured in a shear mode at a heating rate of 5 ° C./min to determine the shear storage elastic modulus of the pressure-sensitive adhesive layer (that is, the pressure-sensitive adhesive layer before photocuring) at 85 ° C. The results are shown in Tables 1 and 2. In addition, "ne" in the table indicates that it has not been measured.

(2) Measurement of Elastic Modulus after Curing The laminated sheet was irradiated with ultraviolet rays having an integrated light amount of 3000 mJ / cm ² using a high-pressure mercury lamp (300 mW / cm ² ) to cure the pressure-sensitive adhesive layer. The cured pressure-sensitive adhesive layers were overlapped to prepare a pressure-sensitive adhesive layer laminate having a thickness of about 1.5 mm. A sample punched into a disk shape having a diameter of 7.9 mm was subjected to dynamic viscoelasticity measurement in the same manner as the above initial elastic modulus measurement, and the shear storage elastic modulus of the pressure-sensitive adhesive layer after photocuring at 85 ° C. was determined. .. The results are shown in Tables 1 and 2.

(3) Durability evaluation Aluminum foil (manufactured by Mitsubishi Aluminum Foil, trade name "" using a 15 μm-thick adhesive on one surface of a polarizing plate (manufactured by Nitto Denko, trade name "REGQ-HC3", thickness 92 mm)) "Nippaku foil" (thickness 12 μm) was used as a support (an adherend bonded to one surface of a support-less double-sided adhesive sheet).
After cutting the laminated sheet to a size of 60 mm × 120 mm, the release liner covering one surface of the adhesive layer (support-less double-sided adhesive sheet) is peeled off, and the exposed adhesive surface is the surface of the support on the polarizing plate side. It was attached to the surface with a hand roller. Next, the release liner covering the other surface of the pressure-sensitive adhesive layer is peeled off, and the exposed pressure-sensitive adhesive surface is a glass plate (manufactured by Matsunami Glass Industry Co., Ltd., trade name "MICRO SLIDE GLASS", product number "S", thickness 1.3 mm, By adhering to haze 0.1% (water edge polishing), a laminated body in which a glass plate, an adhesive layer (supportless double-sided adhesive sheet), a polarizing plate, and aluminum foil were laminated in this order was obtained.
This laminate is autoclaved (50 ° C., 0.5 MPa, 15 minutes) and then irradiated with ultraviolet rays with an integrated light intensity of 3000 mJ / cm ² from the glass plate side using a high-pressure mercury lamp (300 mW / cm ² ). The pressure-sensitive adhesive layer was cured to prepare a sample for durability evaluation.
This evaluation sample was stored in an environment of 85 ° C. for 24 hours, and then visually observed in an environment of 23 ° C. and 50% RH, and the durability was evaluated in the following three stages. The results are shown in Tables 1 and 2. In addition, when the pressure-sensitive adhesive sheet according to any of the examples was used, no bubbles were observed immediately after the preparation of the durability evaluation sample.
E: No bubbles were observed (excellent in durability).
P: Generation of bubbles was clearly observed (poor durability).

(4) Peeling strength (normal peeling strength)
The release liner covering one surface of the pressure-sensitive adhesive layer (supportless double-sided pressure-sensitive adhesive sheet) was peeled off from the laminated sheet, and a PET film having a thickness of 25 μm was attached to the exposed pressure-sensitive adhesive surface for lining. This was cut into a size of 20 mm in width and 100 mm in length to prepare a test piece.
In an environment of 23 ° C. and 50% RH, the release liner covering the other surface of the adhesive layer is peeled off from the test piece, and the exposed adhesive surface is a glass plate (Gorilla Glass 3 manufactured by Corning Inc.) as an adherend. ), A 2 kg rubber roller was reciprocated once and crimped. After autoclaving treatment (50 ° C., 0.5 MPa, 15 minutes), a high-pressure mercury lamp (300 mW / cm ² ) is used to irradiate the glass plate side with ultraviolet rays having an integrated light amount of 3000 mJ / cm ² for adhesion. The agent layer was cured.
Then, in an environment of 23 ° C. and 50% RH, a tensile tester (manufactured by Minevea, universal tensile compression tester, device name "tensile compression tester, TCM-1kNB") was used to achieve a tensile speed of 300 mm / min. The peel strength of the test piece from the adherend under the condition of a peel angle of 180 degrees (however, the peel strength until the transition to the water peeling force measurement of (5) below, that is, until the distilled water is supplied to the peeling interface. ) Was measured. The measurement was performed three times, and the average value thereof was converted into a value per 10 mm width (unit: N / 10 mm) and shown in Tables 1 and 2. The peel strength was measured so that the peeling of the test piece attached to the adherend proceeded from bottom to top.

(5) Water peeling force In the measurement of the normal peeling strength, 20 μL of distilled water is formed at a portion (peeling interface) where the test piece starts to separate from the adherend during the measurement of the peeling strength of the test piece from the adherend. Was supplied, and the peel strength after the distilled water was supplied was measured. The measurement was performed for each measurement of the normal peel strength (that is, three times), and the average value thereof was converted into a value per 10 mm width (unit: N / 10 mm) and shown in Tables 1 and 2.
Here, the measurement of the normal peel strength and the measurement of the water peeling force were continuously performed for each test piece, but the measurement of the normal peeling strength and the measurement of the water peeling force were performed by different test pieces. May be good. For example, when it is difficult to prepare a test piece having a sufficient length for performing continuous measurement, a mode in which measurement is performed using different test pieces can be adopted.

As shown in Tables 1 and 2, the pressure-sensitive adhesive sheets of Examples 1 to 6 using the predetermined photoreactive monomer (B) showed excellent adhesion durability after photocuring and also had good peel strength. ..

Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of claims. The techniques described in the claims include various modifications and modifications of the specific examples illustrated above.

1, 2 Adhesive sheet 10 Adhesive layer 10A One surface (adhesive surface)
10B Other surface 20 Support 20A First surface 20B Second surface (back surface)
30, 31, 32 Peeling liner 50 Adhesive sheet with peeling liner 70 Optical member 100 Member with adhesive sheet

Claims (10)

An adhesive sheet having an adhesive layer,
The pressure-sensitive adhesive layer contains an acrylic polymer (A) and a photoreactive monomer (B).
The photoreactive monomer (B) is a compound B having two or more ethylenically unsaturated groups and an oxyalkylene structural unit in the molecule.
The compound B is a pressure-sensitive adhesive sheet having a molecular weight of 250 or less per ethylenically unsaturated group. The pressure-sensitive adhesive sheet according to claim 1, wherein the pressure-sensitive adhesive layer contains 35 mmol or more of ethylenically unsaturated groups per 100 g of the acrylic polymer. The adhesive according to claim 1 or 2, wherein the content of the photoreactive monomer (B) in the pressure-sensitive adhesive layer is more than 0 parts by weight and less than 20 parts by weight with respect to 100 parts by weight of the acrylic polymer. Sheet. The pressure-sensitive adhesive sheet according to any one of claims 1 to 3, wherein the shear storage elastic modulus at 85 ° C. after photo-curing of the pressure-sensitive adhesive layer is 30 kPa or more. The pressure-sensitive adhesive sheet according to any one of claims 1 to 4, wherein the shear storage elastic modulus at 85 ° C. after photo-curing of the pressure-sensitive adhesive layer is 65 kPa or less. The pressure-sensitive adhesive sheet according to any one of claims 1 to 5, wherein the shear storage elastic modulus of the pressure-sensitive adhesive layer at 85 ° C. is less than 30 kPa. The adhesive sheet according to any one of claims 1 to 6, wherein the peel strength measured by the following procedure is 5.0 N / 10 mm or more.
[Peeling strength measurement procedure]
The surface of the pressure-sensitive adhesive layer is pressure-bonded to a glass plate by reciprocating a 2 kg rubber roller once, autoclaving (50 ° C., 0.5 MPa, 15 minutes), and then an integrated light amount of 3000 mJ / cm from the glass plate side. ^The pressure-sensitive adhesive layer is photocured by irradiating with the ultraviolet rays of No. ² , and then the peeling strength at the time of peeling from the glass plate is measured under the conditions of a tensile speed of 300 mm / min and a peeling angle of 180 degrees in an atmosphere of 25 ° C. .. The item according to any one of claims 1 to 7, wherein the number of the oxyalkylene structural units contained in the photoreactive monomer (B) is less than 2 per the ethylenically unsaturated group contained in the compound. Adhesive sheet. An optical member with an adhesive sheet, comprising the adhesive sheet according to any one of claims 1 to 8 and an optical member bonded to one surface of the adhesive sheet. Attaching the adhesive sheet according to any one of claims 1 to 8 to the adherend,
By irradiating the pressure-sensitive adhesive sheet with ultraviolet rays to photo-curing the pressure-sensitive adhesive layer,
A method for producing a laminate, which comprises the above in this order.

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