JP6919868B2 - Adhesive sheet - Google Patents

Description

The present invention relates to an adhesive sheet.

A general pressure-sensitive adhesive sheet is composed of a base material, a pressure-sensitive adhesive layer formed on the base material, and a release material provided on the pressure-sensitive adhesive layer as needed. If is provided, the release material is peeled off, and the exposed surface of the pressure-sensitive adhesive layer is brought into contact with the adherend and attached.
In such a pressure-sensitive adhesive sheet, in order to exhibit high adhesive strength to an adherend, the pressure-sensitive adhesive composition, which is a material for forming the pressure-sensitive adhesive layer, contains a pressure-sensitive adhesive which is an oligomer component together with a pressure-sensitive adhesive resin. In some cases.

For example, in Patent Document 1, a heat-sensitive pressure-sensitive adhesive containing a predetermined amount of a pressure-sensitive adhesive, a solid plasticizer, and an epoxy compound is applied onto a base material together with an acrylic polymer having a carboxyl group. Adhesive sheets are disclosed.
Further, Patent Document 2 discloses a pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive layer containing an acrylic copolymer composed of a predetermined monomer and a pressure-sensitive adhesive is laminated on a predetermined vinyl chloride resin sheet base material. Has been done.

Japanese Unexamined Patent Publication No. 08-060128 Japanese Unexamined Patent Publication No. 10-017830

By the way, as described in Patent Documents 1 and 2, the pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer containing a tackifier as an oligomer component on the base material has a temporal adhesion between the base material and the pressure-sensitive adhesive layer. In some cases, peeling may occur at the interface between the base material and the pressure-sensitive adhesive layer.
According to the studies by the present inventors, the pressure-sensitive adhesive in the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet may be liable to be unevenly distributed on the base material side with time, and in such a case, the base material and the pressure-sensitive adhesive layer It was found that the interlayer adhesion was reduced and peeling was likely to occur at the interface between the base material and the pressure-sensitive adhesive layer.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an adhesive sheet having good adhesive strength and capable of maintaining excellent interlayer adhesion between a base material and an adhesive layer. And.

In the pressure-sensitive adhesive sheet in which the pressure-sensitive adhesive layer containing the pressure-sensitive resin and the pressure-sensitive adhesive is directly laminated on the base material, the present inventors form the pressure-sensitive adhesive layer as a multi-layer structure having two or more layers to form a multi-layer structure. The present invention has been completed by finding that the above problems can be solved by adjusting a specific parameter indicating the distribution of the tackifier in each layer to an appropriate range.

That is, the present invention provides the following [1] to [13].
[1] A pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive layer containing a pressure-sensitive adhesive resin and a pressure-sensitive adhesive is directly laminated on a base material.
The pressure-sensitive adhesive layer comprises a multilayer structure having at least a layer (Xα) containing a surface (α) having adhesiveness and a layer (Xβ) containing a surface (β) directly laminated with the base material.
An adhesive sheet in which the layer (Xα) and the layer (Xβ) satisfy the following requirements (I) and (II).
-Requirement (I): In the Raman spectrum of the layer (Xα) obtained by measurement by Raman spectroscopy, the intensity ratio I (Xα) of the layer (Xα) calculated from the following formula (1) is 0. It is 30 to 20.00.
-Requirement (II): In the Raman spectrum of the layer (Xβ) obtained by measurement by Raman spectroscopy, the intensity ratio I (Xβ) of the layer (Xβ) calculated from the following formula (1) is the layer. It is smaller than the intensity ratio I (Xα) of (Xα).
Formula (1): Strength ratio I = [Peak height of peak derived from the tackifier] / [Peak height of peak derived from components other than the tackifier]
[2] The pressure-sensitive adhesive sheet according to the above [1], wherein the strength ratio I (Xβ) of the layer (Xβ) is 0 to 15.0.
[3] The ratio of the intensity ratio I (Xβ) of the layer (Xβ) to the intensity ratio I (Xα) of the layer (Xα) [I (Xβ) / I (Xα)] is 0 to 0.90. The adhesive sheet according to the above [1] or [2].
[4] Any one of the above [1] to [3], wherein the composition (xβ) which is a material for forming the layer (Xβ) contains the adhesive resin and substantially does not contain the tackifier. Adhesive sheet described in.
[5] The above [1] to [4], wherein the composition (xα) which is a material for forming the layer (Xα) contains 100 parts by mass of the adhesive resin and 1 part by mass or more of the tackifier. The adhesive sheet according to any one of the above.
[6] Any of the above [1] to [5], wherein the pressure-sensitive adhesive layer is a multilayer structure in which at least a layer (Xβ), a layer (Y1), and a layer (Xα) are laminated in this order. The adhesive sheet described in item 1.
[7] In the Raman spectrum of the layer (Y1) obtained by measurement by Raman spectroscopy, the intensity ratio I (Y1) of the layer (Y1) calculated from the above formula (1) is 0 to 15.0. The adhesive sheet according to the above [6].
[8] In the Raman spectrum of the layer (Y1) obtained by measurement by Raman spectroscopy, the layer (Y1) is calculated from the above formula (1) with respect to the intensity ratio I (Xα) of the layer (Xα). The adhesive sheet according to the above [6] or [7], wherein the ratio [I (Y1) / I (Xα)] of the strength ratio I (Y1) is 0 to 0.90.
The pressure-sensitive adhesive sheet according to any one of the above [6] to [8], wherein the layer (Y1) is a layer containing fine particles.
[10] The pressure-sensitive adhesive sheet according to [9] above, wherein the composition (y1), which is a material for forming the layer (Y1), contains 15 to 100% by mass of the fine particles.
[11] The adhesive sheet according to the above [9] or [10], which has an amorphous recess on the surface (α) of the layer (Xα).
[12] On the surface (α) of the layer (Xα), at least a coating film (xα') composed of a composition (xα) which is a material for forming the layer (Xα) and a composition which is a material for forming the layer (Y1). The above-mentioned [ 9] The adhesive sheet according to any one of [11].
[13] The above-mentioned [1] to [12], wherein the tackifier includes one or more selected from a rosin-based tackifier, a terpene-based tackifier, a styrene-based tackifier, and a petroleum-derived tackifier. ] The adhesive sheet according to any one of the items.

The pressure-sensitive adhesive sheet of the present invention has good adhesive strength and can maintain good interlayer adhesion between the base material and the pressure-sensitive adhesive layer.

It is sectional drawing of the adhesive sheet which shows an example of the structure of the adhesive sheet of this invention. It is sectional drawing for demonstrating the operation for obtaining the Raman spectrum by Raman spectroscopy for each layer of the pressure-sensitive adhesive layer of a pressure-sensitive adhesive sheet. It is sectional drawing of the easy-sticking adhesive sheet which shows an example of the structure of the easy-sticking pressure-sensitive adhesive sheet which is one aspect of this invention. It is a plane schematic view of the surface (α) when the pressure-sensitive adhesive layer which the easy-sticking pressure-sensitive adhesive sheet which is one aspect of this invention has is observed from the surface (α) side. 6 is a graph showing the relationship between the measurement position (distance from the surface (β)) and the strength ratio I at the measurement position in the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet produced in Example 1. Using a digital microscope, a region (D) surrounded by an arbitrarily selected rectangle of 8 mm in length × 10 mm in width on the exposed surface (α) of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet produced in Example 1 is used. It is a binarized image of the image taken from the surface (α) side of the pressure-sensitive adhesive layer. The black portion of the binarized image corresponds to a flat surface, and the white portion corresponds to a concave portion. Using a digital microscope, a region (D) surrounded by an arbitrarily selected rectangle of 8 mm in length × 10 mm in width on the exposed surface (α) of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet produced in Example 2 is used. It is a binarized image of the image taken from the surface (α) side of the pressure-sensitive adhesive layer. The black portion of the binarized image corresponds to a flat surface, and the white portion corresponds to a concave portion. Using a digital microscope, a region (D) surrounded by an arbitrarily selected rectangle of 8 mm in length × 10 mm in width on the exposed surface (α) of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet produced in Example 3 is used. It is a binarized image of the image taken from the surface (α) side of the pressure-sensitive adhesive layer. The black portion of the binarized image corresponds to a flat surface, and the white portion corresponds to a concave portion.

In the present invention, for example, the description of "YY containing an XX component as a main component" or "YY mainly composed of an XX component" means that "the component having the highest content among the components contained in YY is the XX component". It means "there is". The specific content of the XX component in the description is usually 50% by mass or more, preferably 65 to 100% by mass, more preferably 75 to 100% by mass, and further, based on the total amount of YY (100% by mass). It is preferably 85 to 100% by mass.
Further, in the present invention, for example, "(meth) acrylic acid" means both "acrylic acid" and "methacrylic acid", and other similar terms are also the same.
Further, with respect to a preferable numerical range (for example, a range such as content), the lower limit value and the upper limit value described stepwise can be combined independently. For example, from the description of "preferably 10 to 90, more preferably 30 to 60", the "preferable lower limit value (10)" and the "more preferable upper limit value (60)" are combined to obtain "10 to 60". You can also do it.

[Structure of Adhesive Sheet of the Present Invention]
In the pressure-sensitive adhesive sheet of the present invention, a pressure-sensitive adhesive layer containing a pressure-sensitive resin and a pressure-sensitive adhesive is directly laminated on a base material, and the pressure-sensitive adhesive layer is a layer (Xα) containing a surface (α) having adhesiveness. , Consists of a multilayer structure having at least a layer (Xβ) including a surface (β) that is directly laminated with the base material.

First, the structure of the pressure-sensitive adhesive sheet of the present invention will be described. FIG. 1 is a schematic cross-sectional view showing an example of the configuration of the pressure-sensitive adhesive sheet of the present invention.
Examples of the pressure-sensitive adhesive sheet according to one aspect of the present invention include a pressure-sensitive adhesive sheet 1a in which the pressure-sensitive adhesive layer 12 is directly laminated on the base material 11, as shown in FIG. 1 (a). The pressure-sensitive adhesive layer 12 contained in the pressure-sensitive adhesive sheet 1a of FIG. 1A is a layer (Xα) including a surface (α) 12a having adhesiveness to be attached to an adherend and a surface (Xα) directly laminated with the base material 11. It is composed of a two-layer multilayer structure having a layer (Xβ) containing β) 12b.

Further, in one aspect of the present invention, as shown in FIG. 1B, a three-layer multilayer structure in which the layer (Xβ), the layer (Y1), and the layer (Xα) are laminated in this order from the base material 11 side. The pressure-sensitive adhesive sheet 1b having the pressure-sensitive adhesive layer 12 composed of the same may be used.
From the viewpoint of handleability, the pressure-sensitive adhesive sheets 1a and 1b shown in FIG. 1 may have a structure in which a release material is further laminated on the adhesive surface (α) 12a of the pressure-sensitive adhesive layer 12.

In each layer of the multilayer structure constituting the pressure-sensitive adhesive layer 12, two adjacent layers are formed from different compositions to form a boundary that separates the two layers. There is.
For example, in the pressure-sensitive adhesive sheet 1a of FIG. 1A, the composition (xα) which is the material for forming the layer (Xα) and the composition (xβ) which is the material for forming the layer (Xβ) are different from each other.
Further, in the pressure-sensitive adhesive sheet 1b of FIG. 1B, the composition (y1) which is the material for forming the layer (Y1) is the composition (xα) and the layer (Xβ) which are the materials for forming the layer (Xα). It is different from both of the composition (xβ) which is a forming material. However, in the configuration such as the pressure-sensitive adhesive sheet 1b, the composition (xα) and the composition (xβ) may be different from each other or may be the same.

The two adjacent layers included in the multilayer structure may be in a state in which a part of the boundary between the two layers is mixed.
That is, in the pressure-sensitive adhesive layer 12 of the pressure-sensitive adhesive sheet 1a of FIG. 1 (a), a part of the boundary between the layer (Xα) and the layer (Xβ) may be mixed. In the pressure-sensitive adhesive layer 12 of the pressure-sensitive adhesive sheet 1b, a state in which at least one of the boundary between the layer (Xα) and the layer (Y1) and the boundary between the layer (Y1) and the layer (Xβ) is partially mixed. It may be.

From the viewpoint of forming an adhesive sheet with improved blister resistance, the layer (Y1) is preferably a layer containing fine particles.
The content of the fine particles in the layer (Y1) is preferably 15 to 100% by mass, more preferably 20 to 95% by mass, and more preferably 25 to 25 to 100% by mass with respect to the total mass (100% by mass) of the layer (Y1). It is 90% by mass, more preferably 30 to 85% by mass, and even more preferably 35 to 80% by mass.

On the other hand, fine particles may be contained in the layer (Xα) and the layer (Xβ), but from the viewpoint of improving the adhesive strength and the interlayer adhesion between the base material and the pressure-sensitive adhesive layer. , The smaller the content of the fine particles contained in the layer (Xα) and the layer (Xβ), the more preferable.
The content of the fine particles in the layer (Xβ) and the layer (Xα) is preferably less than 15% by mass, based on the total mass (100% by mass) of the layer (Xβ) or the layer (Xα), respectively. It is preferably 0 to 13% by mass, more preferably 0 to 10% by mass, still more preferably 0 to 5% by mass, and even more preferably 0% by mass.

[Adhesive layer]
The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet of the present invention contains a pressure-sensitive resin and a pressure-sensitive adhesive, but preferably further contains a cross-linking agent. In addition, the pressure-sensitive adhesive layer may contain a general-purpose additive, if necessary, as long as the effects of the present invention are not impaired.
Further, from the viewpoint of forming a pressure-sensitive adhesive sheet having improved blister resistance, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet of the present invention preferably further contains fine particles.

The thickness of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet of the present invention is preferably 1 to 300 μm, more preferably 5 to 150 μm, and even more preferably 10 to 75 μm.

The shear storage elastic modulus of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive layer of the present invention at 100 ° C. is preferably 9.0 × 10 ³ Pa or more, more preferably 1.0 × 10 ⁴ Pa or more, still more preferably 2.0 ×. It is 10 ⁴ Pa or more.
In the present invention, the shear storage elastic modulus of the pressure-sensitive adhesive layer at 100 ° C. is measured at a frequency of 1 Hz using a viscoelasticity measuring device (for example, manufactured by Rheometrics, device name “DYNAMIC ANALYZER RDA II”). It means the measured value.

The adhesive force on the surface (α) of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet of the present invention is preferably 0.5 N / 25 mm or more, more preferably 2.0 N / 25 mm or more, more preferably 3.0 N / 25 mm or more, and further. It is preferably 4.0 N / 25 mm or more, and even more preferably 7.0 N / 25 mm or more.
The value of the adhesive strength of the adhesive sheet means a value measured by the method described in the examples.

Hereinafter, each component contained in the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to one aspect of the present invention will be described.

(Adhesive resin)
The adhesive resin contained in the pressure-sensitive adhesive layer may be any resin having adhesiveness, and examples thereof include acrylic resin, urethane resin, rubber resin, and silicone resin.
These adhesive resins may be used alone or in combination of two or more.

Among these, from the viewpoint of good adhesive properties and weather resistance, the adhesive resin preferably contains an acrylic resin and a rubber resin, and more preferably contains an acrylic resin.
When the pressure-sensitive adhesive layer contains a cross-linking agent, the pressure-sensitive adhesive resin preferably contains a resin having a functional group, and more preferably contains an acrylic resin having a functional group.
The functional group is a group that serves as a starting point for cross-linking with a cross-linking agent, and examples thereof include a hydroxy group, a carboxy group, an epoxy group, an amino group, a cyano group, a keto group, an alkoxysilyl group, and the like. preferable.
Further, from the viewpoint of maintaining good adhesive properties regardless of the usage environment, the adhesive resin is preferably an ultraviolet non-curable adhesive resin, and more preferably an ultraviolet non-curable acrylic resin. preferable.
The "ultraviolet non-curable adhesive resin" means an adhesive resin that does not have a polymerizable functional group that can react with ultraviolet rays.

The mass average molecular weight (Mw) of the adhesive resin is usually 10,000 or more, preferably 10,000 to 2 million, more preferably 30,000 to 1.5 million, still more preferably 50,000 to 1.3 million, and even more preferably 100,000. ~ 1.1 million.

The content of the adhesive resin in the pressure-sensitive adhesive layer is preferably 10% by mass or more, more preferably 20% by mass or more, still more preferably 30% by mass or more, based on the total amount (100% by mass) of the pressure-sensitive adhesive layer. It is still more preferably 40% by mass or more, preferably 99.9% by mass or less, and even more preferably 99.0% by mass or less.
In particular, in the pressure-sensitive adhesive layer having a fine particle content of less than 3% by mass, the content of the pressure-sensitive resin is preferably 50% by mass or more, more preferably 50% by mass or more, based on the total amount (100% by mass) of the pressure-sensitive adhesive layer. It is 60% by mass or more, more preferably 70% by mass or more, and preferably 99.9% by mass or less, more preferably 99.0% by mass or less.
In addition, in this specification, the term "the total amount of the pressure-sensitive adhesive layer" can be read as "the total amount of the active ingredient of the composition which is the material for forming the pressure-sensitive adhesive layer". Further, the "active ingredient of the composition" refers to a component in the composition excluding the diluting solvent.

(Adhesive imparting agent)
The tackifier used in the present invention is a component that supplementarily improves the adhesive properties of the adhesive resin, and refers to an oligomer having a mass average molecular weight (Mw) of usually less than 10,000, and is the above-mentioned adhesive resin. It is something that can be distinguished.
The mass average molecular weight (Mw) of the tackifier is usually less than 10,000, but is preferably 400 to 8000, more preferably 500 to 5000, and more preferably 800 to 3500.

The tackifier preferably contains one or more selected from a rosin-based tackifier, a terpene-based tackifier, a styrene-based tackifier, and a petroleum-derived tackifier.
These tackifiers may be used alone or in combination of two or more having different softening points and structures.

Examples of the rosin-based tackifier include rosin-based resins such as rosin resin, rosin ester resin, and rosin-modified phenol resin, and hydrogenated rosin-based resin obtained by hydrogenating these rosin-based resins.

Examples of the terpene-based tackifier include terpene-based resins such as terpene resins, aromatic-modified terpene resins, and terpene phenol-based resins, and hydrogenated terpene-based resins obtained by hydrogenating these terpene-based resins.

Examples of the styrene-based tackifier include a styrene-based resin obtained by copolymerizing a styrene-based monomer such as α-methylstyrene or β-methylstyrene with an aliphatic monomer, and hydrogenation of these styrene-based resins. Examples thereof include styrene-based hydride resin.

Examples of petroleum-derived tackifiers include C5-based petroleum resins obtained by copolymerizing C5 distillates such as penten, isoprene, piperin, and 1.3-pentadien produced by thermal decomposition of petroleum naphtha, and C5-based petroleum resins. Hydrogenated petroleum resin of petroleum resin; C9-based petroleum resin obtained by copolymerizing C9 distillates such as inden and vinyl toluene produced by thermal decomposition of petroleum naphtha, and hydride petroleum resin of this C9-based petroleum resin; etc. Can be mentioned.

The softening point of the tackifier is preferably 80 ° C. or higher, more preferably 80 to 180 ° C., still more preferably 83 to 170 ° C., and even more preferably 85 to 150 ° C.
In the present invention, the "softening point" of the tackifier means a value measured in accordance with JIS K 2531.
Further, when two or more kinds of a plurality of tackifiers are used, the content ratios of the plurality of tackifiers are prepared so that the weighted average of the softening points of the plurality of tackifiers belongs to the above range. Is preferable.

The content of the tackifier is preferably 1 part by mass or more, more preferably 1 to 200 parts by mass, still more preferably 3 to 150 parts by mass, based on 100 parts by mass of the adhesive resin contained in the pressure-sensitive adhesive layer. More preferably, it is 5 to 90 parts by mass.

(Crosslinking agent)
The pressure-sensitive adhesive layer contained in the pressure-sensitive adhesive sheet according to one aspect of the present invention preferably further contains a cross-linking agent, and more preferably contains the cross-linking agent together with a resin having a functional group as the pressure-sensitive adhesive resin.
Examples of the cross-linking agent include isocyanate-based cross-linking agents, epoxy-based cross-linking agents, aziridine-based cross-linking agents, and metal chelate-based cross-linking agents.
These cross-linking agents may be used alone or in combination of two or more.

The isocyanate-based cross-linking agent is, for example, an aromatic polyisocyanate such as tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate; an aliphatic polyisocyanate such as hexamethylene diisocyanate; an alicyclic polyisocyanate such as isophorone diisocyanate or hydrogenated diphenylmethane diisocyanate; In addition, an adduct compound which is a reaction product of these compounds with a biuret form, an isocyanurate form, and a low molecular weight active hydrogen-containing compound (ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, castor oil, etc.); etc. Can be mentioned.

Examples of the epoxy-based cross-linking agent include ethylene glycol glycidyl ether, 1,3-bis (N, N-diglycidyl aminomethyl) cyclohexane, N, N, N', N'-tetraglycidyl-m-xylylenediamine, and the like. Examples thereof include 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidyl aniline, and diglycidyl amine.

Examples of the aziridine-based cross-linking agent include diphenylmethane-4,4'-bis (1-aziridine carboxamide), trimethylpropanthry-β-aziridinyl propionate, and tetramethylolmethanetri-β-aziridinyl. Propionate, toluene-2,4-bis (1-aziridine carboxamide), triethylene melamine, bisisophthaloyl-1- (2-methylaziridine), tris-1- (2-methylaziridine) phosphine, Examples thereof include trimethylolpropantri-β- (2-methylaziridine) propionate.

Examples of the metal chelate-based cross-linking agent include chelate compounds in which the metal atom is aluminum, zirconium, titanium, zinc, iron, tin, etc., from the viewpoint of facilitating the formation of recesses on the surface (α) of the pressure-sensitive adhesive layer. Aluminum chelate-based cross-linking agents are preferred.
Examples of the aluminum chelate-based cross-linking agent include diisopropoxyaluminum monooleyl acetoacetate, monoisopropoxyaluminum bisoleyl acetoacetate, monoisopropoxyaluminum monooleate monoethylacetate, diisopropoxyaluminum monolauryl acetoacetate, and diisopropoxyaluminum monooleyl acetoacetate. Examples thereof include isopropoxyaluminum monostearylacetate and diisopropoxyaluminum monostearylacetate.

When the cross-linking agent is contained in the pressure-sensitive adhesive layer, the content of the cross-linking agent is preferably 0.01 to 15 parts by mass, more preferably 0, based on 100 parts by mass of the pressure-sensitive adhesive resin contained in the pressure-sensitive adhesive layer. .1 to 10 parts by mass, more preferably 0.3 to 7.0 parts by mass.

(General-purpose additive)
The pressure-sensitive adhesive layer contained in the pressure-sensitive adhesive sheet according to one aspect of the present invention may further contain a general-purpose additive used for general pressure-sensitive adhesives.
Examples of the general-purpose additive include antioxidants, softeners (plasticizers), rust inhibitors, pigments, dyes, retarders, reaction accelerators, ultraviolet absorbers and the like.
Each of these general-purpose additives may be used alone or in combination of two or more.
When these general-purpose additives are contained in the pressure-sensitive adhesive layer, the content of each general-purpose additive is preferably 0.0001 to 60 parts by mass with respect to 100 parts by mass of the adhesive resin contained in the pressure-sensitive adhesive layer. , More preferably 0.001 to 50 parts by mass.

(Fine particles)
The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to one aspect of the present invention preferably further contains fine particles from the viewpoint of making the pressure-sensitive adhesive sheet having improved blister resistance.
By forming the pressure-sensitive adhesive layer containing fine particles, it is possible to improve the shape retention of the pressure-sensitive adhesive layer when the obtained pressure-sensitive adhesive sheet is attached to an adherend, and the pressure-sensitive adhesive sheet can be used at a high temperature. If this is the case, the generation of blister can be effectively suppressed.
The average particle size of the fine particles is preferably 0.01 to 100 μm, more preferably 0.05 to 25 μm, and even more preferably 0.1 to 10 μm.

The fine particles are not particularly limited, and examples thereof include inorganic particles such as silica particles, metal oxide particles, barium sulfate, calcium carbonate, magnesium carbonate, glass beads, and smectite, and organic particles such as acrylic beads.
These fine particles may be used alone or in combination of two or more.
Among these fine particles, one or more selected from silica particles, metal oxide particles, and smectite are preferable, and silica particles are more preferable.

The silica particles used in one aspect of the present invention may be either dry silica or wet silica.
Further, the silica particles used in one embodiment of the present invention are organically modified silica surface-modified with an organic compound having a reactive functional group, or inorganically modified silica surface-treated with an inorganic compound such as sodium aluminate or sodium hydroxide. , And organic-inorganic modified silica surface-treated with these organic compounds and inorganic compounds, organic-inorganic modified silica surface-treated with an organic-inorganic hybrid material such as a silane coupling agent, and the like may be used.
In addition, these silica particles may be a mixture consisting of two or more kinds.

Examples of the metal oxide particles include particles made of titanium oxide, alumina, boehmite, chromium oxide, nickel oxide, copper oxide, titanium oxide, zirconium oxide, indium oxide, zinc oxide, and a metal oxide selected from a composite oxide thereof. Etc., and sol particles composed of these metal oxides are also included.

Examples of smectite include montmorillonite, bidelite, hectorite, saponite, stebunsite, nontronite, saponite and the like.

When the pressure-sensitive adhesive layer contains fine particles, the content of the fine particles is preferably 3 to 90% by mass, more preferably 5 to 80% by mass, based on the total amount (100% by mass) of the pressure-sensitive adhesive layer. It is preferably 7 to 70% by mass, and even more preferably 9 to 60% by mass.

<Layer structure of adhesive layer>
The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet of the present invention is a multilayer structure having at least a layer (Xα) and a layer (Xβ), and the layer (Xα) and the layer (Xβ) are the following requirements (I) and (II). ) Is satisfied.
-Requirement (I): In the Raman spectrum of the layer (Xα) obtained by measurement by Raman spectroscopy, the intensity ratio I (Xα) of the layer (Xα) calculated from the following formula (1) is 0. It is 30 to 20.00.
-Requirement (II): In the Raman spectrum of the layer (Xβ) obtained by measurement by Raman spectroscopy, the intensity ratio I (Xβ) of the layer (Xβ) calculated from the following formula (1) is the layer. It is smaller than the intensity ratio I (Xα) of (Xα).
Formula (1): Strength ratio I = [Peak height of peak derived from the tackifier] / [Peak height of peak derived from components other than the tackifier]

In the present specification, the "Raman spectrum obtained by measurement by Raman spectroscopy" is a graph showing the relationship between Raman shift and Raman scattering intensity with Raman scattering intensity on the vertical axis and Raman shift on the horizontal axis. Means.
As a specific method for obtaining the Raman spectrum, as shown in FIG. 2, a pressure-sensitive adhesive that is orthogonal to the surface (α) 12a and the surface (β) 12b of the pressure-sensitive adhesive layer 12 included in the pressure-sensitive adhesive sheet 1 to be measured. A Raman spectrum can be obtained by detecting the Raman scattered light 52 generated when the excitation laser 51 is vertically irradiated from the laser irradiation device 50 to the cross section 121 of the layer 12 with a detector.

The “peak derived from the tackifier” in the above formula (1) refers to a peak generated by the presence of the tackifier in the Raman spectrum obtained by measuring the target layer by Raman spectroscopy.
Similarly, the “peak derived from a component other than the tackifier” is the presence of a component other than the tackifier in the Raman spectrum obtained by measuring the target layer by Raman spectroscopy as described above. Refers to the peak caused by.

The "components other than the pressure-sensitive adhesive" refers to components other than the pressure-sensitive adhesive contained in the pressure-sensitive adhesive layer, and includes not only adhesive resins but also general-purpose additives such as cross-linking agents added as needed. included.
However, the content of general-purpose additives such as cross-linking agents is smaller than that of adhesive resins. Therefore, in the Raman spectrum observed when the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition excluding the pressure-sensitive adhesive is measured, the intensity of the peak derived from the general-purpose additive is the peak derived from the pressure-sensitive adhesive resin. Compared to, it becomes relatively weak. Therefore, the strong peak in this Raman spectrum almost coincides with the adhesive resin which is the main component. Therefore, in fact, the "peak derived from a component other than the tackifier" can be considered as a peak derived from the adhesive resin.

Further, the "peak derived from the tackifier" and the "peak derived from a component other than the tackifier" in the above formula (1) refer to the peak selected through the following (i) to (iv). ..
A specific example method from the measurement by Raman spectroscopy to the calculation of "intensity ratio I of each layer" is as described in Examples described later.
(I) A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer (a) formed from a composition containing a pressure-sensitive adhesive resin and a pressure-sensitive adhesive to be measured and, if necessary, containing a general-purpose additive such as a cross-linking agent is prepared. , Install in the same manner as the adhesive sheet 1 shown in FIG. Then, with respect to the cross section 121 of the pressure-sensitive adhesive layer (a) in the pressure-sensitive adhesive sheet, as shown in FIG. 2, from the surface (β) 12b side toward the surface (α) 12a side, 0 along the direction P. The excitation laser 51 is irradiated vertically from the laser irradiation device 50 while shifting the measurement position at regular intervals selected from the range of 5 to 1 μm, and the Raman spectrum (Ra) of the pressure-sensitive adhesive layer (a) at each measurement position. ) Is measured.
(Ii) A pressure-sensitive adhesive having a pressure-sensitive adhesive layer (b) formed from a composition having the same components and content as the composition which is the material for forming the pressure-sensitive adhesive layer (a), except for the "adhesive-imparting agent". A sheet is prepared, and the Raman spectrum (Rb) of the pressure-sensitive adhesive layer (b) is measured by Raman spectroscopy at an arbitrary position on the cross section of the pressure-sensitive adhesive layer (b) under the same conditions as in (i) above. do.
(Iii) For Raman spectra (Ra) and (Rb), the Raman scattering intensity is compared for each Raman shift. At this time, the Raman scattering intensity of a peak _{(p a)} of a specific Raman shift (r) of the Raman spectra (Ra) is the Raman peak at the same Raman shift of a Raman spectrum _{(Rb) (r) (p} b) If the 10-fold of the scattering intensity, the peak of the Raman spectrum (Ra) and (p _a) is determined as "peak derived from tackifier". Also, the peak height calculated in the peak (p _a) and "peak height of the peak derived from a tackifier."
In addition, in (iii), when there are a plurality of corresponding peaks, the peak having the strongest Raman scattering intensity is selected from the corresponding peaks in the Raman spectrum (Ra).
(Iv) In the Raman spectrum (Ra), other peaks that were not determined to be "peaks derived from the tackifier" in (iii) above are defined as "peaks derived from components other than the tackifier" and are said to be the peaks. The peak height calculated in 1 is defined as "the peak height of the peak derived from a component other than the tackifier".
In addition, in (iv), when there are a plurality of corresponding peaks, in Raman spectrum (Rb), among the corresponding peaks, the presence or absence of the tackifier has little influence on the Raman scattering intensity, and Raman scattering A peak with a stronger intensity shall be selected, but may be arbitrarily selected as long as it is of the same degree.

In addition, in (i) above, the boundary between two adjacent layers can be specified by the optical microscope image of the cross section 121 of the pressure-sensitive adhesive layer 12 used when designating the measurement point.
Further, the boundary line between the base material 11 and the layer (Xβ) and the boundary line between the layer (Xα) and the air layer are determined by an optical microscope image, and the adhesive resin is determined from the Raman spectrum obtained by Raman spectroscopy. It can also be determined by the presence or absence of peaks derived from the components forming the adhesive layer such as the tackifier.

The Raman shift in the "peak derived from the tackifier" selected through the above (i) to (iv) can be specified to some extent by the type of the tackifier as follows.
Styrene-based ^{tackifier: 3100cm -1, 1670cm -1, 1660cm} -1, 1650cm -1, 1600cm -1 ~1610cm -1, 1380cm -1, 1000cm -1
· Terpene ^{tackifier: 3100cm -1, 1670cm -1, 1660cm} -1, 1650cm -1, 1600cm -1 ~1610cm -1, 1380cm -1, 1000cm -1
Rosin ^{tackifier: 1670cm -1, 1660cm -1, 1650cm} -1, 1600cm -1 ~1610cm -1, 1380cm -1

Based on the values of "peak peak height derived from the tackifier" and "peak peak height derived from components other than the tackifier" obtained through the above steps (i) to (iv), the above From the formula (1), the "strength ratio I" at each of the measurement positions in the cross section 121 of the pressure-sensitive adhesive layer can be calculated.
In the present invention, "intensity ratio I of each layer" means the average value of the intensity ratio I of all the measurement positions included in the target layer. For example, the “intensity ratio I (Xβ) of the layer (Xβ)” refers to the average value of the intensity ratio I at all the measurement positions included in the layer (Xβ). “Strength ratio I (Xα) of layer (Xα)” and “strength ratio I (Y1) of layer (Y1)” have the same meaning.

In the above requirements (I) and (II), the "intensity ratio" calculated from the above formula (I) using the Raman spectrum obtained by measuring each layer of the multilayer structure constituting the pressure-sensitive adhesive layer by Raman spectroscopy. "I" indirectly indicates the abundance ratio of the tackifier to the components (mainly the tacky resin) other than the tackifier contained in each measurement position.
That is, the "strength ratio I of each layer" is an index showing the degree of the presence of the tackifier in the target layer, and it can be said that the larger the value, the more the tackifier is unevenly distributed. ..

As described above, the present inventors may easily disperse the tackifier in the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet on the base material side with time, and in such a case, the base material and the pressure-sensitive adhesive layer It was thought that the interlayer adhesion of the above would be reduced.
Therefore, in the pressure-sensitive adhesive sheet of the present invention, the strength ratios I (Xα) and (Xβ) of the layer (Xα) and the layer (Xβ) constituting the pressure-sensitive adhesive layer satisfy the requirements (I) and (II). The types and contents of the pressure-sensitive adhesive resin and the pressure-sensitive adhesive constituting the layer (Xα) and the layer (Xβ) are appropriately adjusted.
Therefore, by satisfying the requirement (I), the pressure-sensitive adhesive sheet of the present invention suppresses a decrease in adhesive strength with time on the surface to be attached to the adherend, and exhibits excellent adhesive strength.
Further, since the pressure-sensitive adhesive sheet of the present invention is designed so that the pressure-sensitive adhesive is less likely to be unevenly distributed on the base material side so as to satisfy the requirement (II), excellent interlayer adhesion between the base material and the pressure-sensitive adhesive layer can be obtained. Can be maintained for a long period of time.

In the present invention, as specified in the above requirement (I), the strength ratio I (Xα) of the layer (Xα) including the adhesive surface (α) is 0.30 to 20.00. Within this range, it is possible to suppress a decrease in adhesive strength over time and develop excellent adhesive strength, and also suppress fogging that may occur on the adherend when it is peeled off after being once attached to the adherend. It can be an adhesive sheet to be obtained.
From the above viewpoint, the strength ratio I (Xα) of the layer (Xα) defined in the above requirement (I) is preferably 0.32 to 15.00, more preferably 0.35 to 10.00, and even more preferably 0.35 to 10.00. It is 0.40 to 8.00, more preferably 0.50 to 5.00, and particularly preferably 0.80 to 3.00.

Further, in the present invention, as specified in the above requirement (II), the intensity ratio I (Xβ) of the layer (Xβ) is smaller than the intensity ratio I (Xα) of the layer (Xα).
By designing the layer (Xβ) and the layer (Xα) so as to satisfy the requirement (II), it is possible to obtain an adhesive sheet that maintains excellent interlayer adhesion between the base material and the pressure-sensitive adhesive layer for a long period of time. can.

From the above viewpoint, the intensity ratio I (Xβ) of the layer (Xβ) defined in the above requirement (II) is preferably 0 to 15.0, more preferably 0 to 10.0, and more preferably 0 to 0. It is 8.0, more preferably 0 to 5.0, even more preferably 0 to 3.0, and particularly preferably 0 to 1.5.
In the present invention, the fact that the intensity ratio I (Xβ) of the layer (Xβ) becomes 0 means that the Raman of the layer (Xβ) obtained by measuring at the measurement position included in the layer (Xβ) by Raman spectroscopy. It means that "peak derived from the tackifier" was not observed in the spectrum.

From the above viewpoint, the ratio of the intensity ratio I (Xβ) of the layer (Xβ) to the intensity ratio I (Xα) of the layer (Xα) [I (Xβ) / I (Xα)] is preferably 0 to 0. It is .90, more preferably 0 to 0.80, still more preferably 0 to 0.70, and even more preferably 0 to 0.50.

As the pressure-sensitive adhesive sheet according to one aspect of the present invention, as in the pressure-sensitive adhesive sheet 1b shown in FIG. It may be an adhesive sheet which is a multilayer structure formed by laminating.
When the pressure-sensitive adhesive layer is a multilayer structure composed of a layer (Xβ), a layer (Y1), and a layer (Xα), the layer (Xα) and the layer (Xβ) are the above requirements (I) and (II). It is preferable that the layer (Y1) satisfies at least one of the following requirements (III-1) and (III-2), and the layer (Y1) satisfies the following requirements (III-1) and (III-2). It is more preferable to satisfy both.

-Requirement (III-1): In the Raman spectrum of the layer (Y1) obtained by measurement by Raman spectroscopy, the intensity ratio I (Y1) of the layer (Y1) calculated from the above formula (1) is It is 0 to 15.0.
-Requirement (III-2): In the Raman spectrum of the layer (Y1) obtained by Raman spectroscopy, the intensity ratio of the layer (Xα) to the intensity ratio I (Xα) calculated from the above formula (1). , The ratio of the intensity ratio I (Y1) of the layer (Y1) [I (Y1) / I (Xα)] is 0 to 0.90.
The above requirements (III-1) and (III-2) are provisions for a layer (Y1) which is an intermediate layer that does not include the surface (α) and the surface (β) of the pressure-sensitive adhesive layer.
Further, it is preferable that the intensity ratio I (Y1) of the layer (Y1) is larger than the intensity ratio I (Xβ) of the layer (Xβ), and the intensity ratio I (Y1) of the layer (Y1) is that of the layer (Xβ). It is more preferable that the intensity ratio is larger than the intensity ratio I (Xβ) and smaller than the intensity ratio I (Xα) of the layer (Xα).

By satisfying the requirement (III-1), the pressure-sensitive adhesive sheet can maintain excellent interlayer adhesion between the base material and the pressure-sensitive adhesive layer for a long period of time.
From this point of view, the strength ratio I (Y1) of the layer (Y1) specified in the requirement (III-1) is preferably 0 to 15.0, more preferably 0 to 10.0, and more preferably 0 to 10.0. It is 0 to 8.0, more preferably 0 to 5.0, even more preferably 0 to 3.0, and particularly preferably 0 to 1.5.

Further, by satisfying the requirement (III-2), it is possible to maintain excellent interlayer adhesion between the base material and the pressure-sensitive adhesive layer for a long period of time, and to obtain a pressure-sensitive adhesive sheet having improved adhesive strength.
From this point of view, the ratio of the strength ratio I (Y1) of the layer (Y1) to the strength ratio I (Xα) of the layer (Xα) specified in the requirement (III-2) [I (Y1) / I (Xα). ], It is preferably 0 to 0.90, more preferably 0 to 0.85, still more preferably 0 to 0.80, and even more preferably 0 to 0.70.

The above-mentioned "strength ratio I of each layer" (specifically, "strength ratio I (Xα) of layer (Xα)", "strength ratio I (Xβ) of layer (Xβ)" and "layer (Y1)" The value of the strength ratio I (Y1) ”) can be adjusted by appropriately selecting the type and content of components such as the adhesive resin and the tackifier in the composition which is the material for forming the target layer. be.
Hereinafter, the types and contents of the components contained in the composition which is the material for forming each layer will be described, and an example of adjusting the “strength ratio I of each layer” will be described.

<Composition (xα) which is a material for forming the layer (Xα)>
In one aspect of the present invention, the layer (Xα) is formed from the viewpoint of adjusting the intensity ratio I (Xα) of the layer (Xα) to facilitate the formation of the layer (Xα) satisfying the requirements (I) and (II). The composition (xα) as a material is preferably a composition containing 100 parts by mass of a tacky resin and 1 part by mass or more of a tackifier.
From the above viewpoint, the content of the tackifier in the composition (xα) is preferably 3 parts by mass or more, more preferably 5 parts by mass with respect to 100 parts by mass of the adhesive resin in the composition (xα). As mentioned above, it is more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more.

In addition to facilitating the formation of the layer (Xα) satisfying the requirements (I) and (II), the value of the intensity ratio I (Xβ) of the layer (Xβ) and the intensity ratio I (Y1) of the layer (Y1). From the viewpoint of adjusting the value of to the above-mentioned preferable range, the content of the tackifier in the composition (xα) is preferably 400 parts by mass with respect to 100 parts by mass of the adhesive resin in the composition (xα). Below, it is more preferably 150 parts by mass or less, further preferably 80 parts by mass or less, still more preferably 60 parts by mass or less, and particularly preferably 50 parts by mass or less.

Regarding the content of the adhesive resin in the composition (xα), from the viewpoint of adjusting the strength ratio I of each layer to the above-mentioned preferable range, with respect to the total amount (100% by mass) of the active component of the composition (xα). It is preferably 25% by mass or more, more preferably 40% by mass or more, further preferably 50% by mass or more, still more preferably 60% by mass or more, and preferably 99% by mass or less, more preferably 97% by mass or less. It is more preferably 95% by mass or less, still more preferably 90% by mass or less, and particularly preferably 87% by mass or less.

The composition (xα) preferably further contains a cross-linking agent, and is added as described above in a range that does not affect the strength ratio I (Xα) of the layer (Xα) specified in the requirement (I). The agent may be contained.
Moreover, the composition (xα) may contain the above-mentioned fine particles.
However, the content of the fine particles in the composition (xα) is usually less than 15% by mass, preferably 0 to 13% by mass, more preferably 0 to 13% by mass, based on the total amount (100% by mass) of the active ingredients of the composition (xα). It is 0 to 10% by mass, more preferably 0 to 5% by mass, and even more preferably 0% by mass.

The total content of the tacky resin and the tackifier in the composition (xα) is preferably 70 to 100% by mass, more preferably 70% by mass, based on the total amount (100% by mass) of the active ingredient of the composition (xα). It is 80 to 99.9% by mass, more preferably 90 to 99.5% by mass, and even more preferably 95 to 99.0% by mass.

Examples of the tackifier in the composition (xα) include those described above, but the transfer of the tackifier to other layers other than the layer (Xα) is suppressed, and the strength ratio I of each layer is set within the above-mentioned preferable range. It is preferable to contain at least one selected from a rosin-based tackifier, a terpene-based tackifier, and a styrene-based tackifier, and is selected from the rosin-based tackifier and the terpene-based tackifier. It is more preferable to contain one or more kinds.

The content of one or more tackifiers selected from the rosin-based tackifier and the terpene-based tackifier is preferably the total amount (100% by mass) of the tackifier in the composition (xα). It is 60 to 100% by mass, more preferably 70 to 100% by mass, still more preferably 80 to 100% by mass, and even more preferably 90 to 100% by mass.

As the adhesive resin in the composition (xα), excellent adhesive strength is exhibited, the transfer of the tackifier to other layers other than the layer (Xα) is suppressed, and the strength ratio I of each layer is preferably set as described above. From the viewpoint of adjusting the range, it is preferable to contain an acrylic resin, and an acrylic resin having a functional group is more preferable.
Further, as described above, the acrylic resin is preferably an ultraviolet non-curable acrylic resin.
This acrylic resin may be either a solvent type or an emulsion type.
The content of the acrylic resin is preferably 25 to 100% by mass, more preferably 50 to 100% by mass, still more preferably 50% by mass, based on the total amount (100% by mass) of the adhesive resin contained in the composition (xα). It is 70 to 100% by mass, more preferably 80 to 100% by mass, and even more preferably 100% by mass.

The composition (xα) preferably further contains a cross-linking agent together with an acrylic resin having a functional group.
Examples of the cross-linking agent include the above-mentioned ones, but it is preferable to include one or more selected from a metal chelate-based cross-linking agent, an epoxy-based cross-linking agent, and an aziridine-based cross-linking agent.
The content of the cross-linking agent is preferably 0 with respect to 100 parts by mass of the adhesive resin (or the acrylic resin having a functional group or the acrylic copolymer (P) described later) contained in the composition (xα). It is 0.01 to 15 parts by mass, more preferably 0.1 to 10 parts by mass, and further preferably 0.3 to 7.0 parts by mass.

Examples of the acrylic resin include a polymer having a structural unit derived from an alkyl (meth) acrylate having a linear or branched alkyl group, and a polymer having a structural unit derived from a (meth) acrylate having a cyclic structure. And so on.
The mass average molecular weight (Mw) of the acrylic resin is preferably 50,000 to 1.5 million, more preferably 150,000 to 1.3 million, still more preferably 250,000 to 1.1 million, and even more preferably 350,000 to 900,000. ..

Among the acrylic resins, from the viewpoint of exhibiting excellent adhesive strength, suppressing the transfer of the tackifier to other layers other than the layer (Xα), and adjusting the strength ratio I of each layer to the above-mentioned preferable range. A structural unit (p1) derived from an alkyl (meth) acrylate (p1') having an alkyl group having 1 to 18 carbon atoms (hereinafter, also referred to as "monomer (p1')"), and a functional group-containing monomer (p2'). An acrylic copolymer (P) having a structural unit (p2) derived from (hereinafter, also referred to as “monomer (p2')”) (hereinafter, also referred to as “acrylic copolymer (P)”) is preferable.
Hereinafter, the “acrylic copolymer (P)”, which is suitable among the acrylic resins, will be described.

(Acrylic copolymer (P))
The form of copolymerization of the acrylic copolymer (P) is not particularly limited, and may be any of a block copolymer, a random copolymer, and a graft copolymer.
However, as described above, the acrylic copolymer (P) is preferably an ultraviolet non-curable type.
The method for synthesizing the acrylic copolymer (P) is not particularly limited. For example, a method in which a raw material monomer is dissolved in a solvent and solution-polymerized in the presence of a polymerization initiator, a chain transfer agent, or the like. It is produced by a method of emulsion polymerization in an aqueous system using a raw material monomer in the presence of an emulsifier, a polymerization initiator, a chain transfer agent, a dispersant and the like.

The number of carbon atoms of the alkyl group contained in the monomer (p1') is more preferably 4 to 12, still more preferably 4 to 8, and even more preferably 4 to 6 from the viewpoint of improving the adhesive properties.
Examples of the monomer (p1') include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, and tridecyl (). Examples thereof include meta) acrylate and stearyl (meth) acrylate.
Among these, butyl (meth) acrylate and 2-ethylhexyl (meth) acrylate are preferable, and butyl (meth) acrylate is more preferable.

The content of the structural unit (p1) is preferably 50 to 99.5% by mass, more preferably 60 to 99% by mass, based on the total structural unit (100% by mass) of the acrylic copolymer (P). It is even more preferably 70 to 97% by mass, and even more preferably 80 to 95% by mass.

Examples of the monomer (p2') include a hydroxy group-containing monomer, a carboxy group-containing monomer, an epoxy group-containing monomer, an amino group-containing monomer, a cyano group-containing monomer, a keto group-containing monomer, and an alkoxysilyl group-containing monomer. ..
Among these, a carboxy group-containing monomer is more preferable.
Examples of the carboxy group-containing monomer include (meth) acrylic acid, maleic acid, fumaric acid, itaconic acid and the like, and (meth) acrylic acid is preferable.

The content of the structural unit (p2) is preferably 0.5 to 50% by mass, more preferably 1 to 40% by mass, based on the total structural unit (100% by mass) of the acrylic copolymer (P). It is more preferably 1.5 to 30% by mass, and even more preferably 2 to 20% by mass.

The acrylic copolymer (P) may have a structural unit (p3) derived from other monomers (p3') other than the above-mentioned monomers (p1') and (p2').
Examples of other monomers (p3') include cyclohexyl (meth) acrylate, benzyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, and dicyclopentenyl. Examples thereof include (meth) acrylate having a cyclic structure such as oxyethyl (meth) acrylate and imide (meth) acrylate, vinyl acetate, acrylonitrile, and styrene.

The content of the structural unit (p3) is preferably 0 to 30% by mass, more preferably 0 to 20% by mass, still more preferably, with respect to the total structural unit (100% by mass) of the acrylic copolymer (P). Is 0 to 10% by mass, more preferably 0 to 5% by mass.
The above-mentioned monomers (p1') to (p3') may be used alone or in combination of two or more.

<Composition (xβ) which is a material for forming the layer (Xβ)>
In one aspect of the present invention, it is preferable that the composition (xβ), which is a material for forming the layer (Xβ), is a composition containing the adhesive resin and substantially not containing the tackifier.
The content of the tackifier in the composition which is the material for forming each layer is one factor for increasing the strength ratio I of the target layer. That is, by forming the layer (Xβ) from the composition (xβ) that does not substantially contain the tackifier, the value of the intensity ratio I (Xβ) of the layer (Xβ) becomes low, as described above. It becomes easy to adjust to the preferable range of, and it becomes easy to form a layer (Xβ) satisfying the requirement (II).

In addition, in this specification, "substantially containing no tackifier" means that the content of the tackifier is 0.01 with respect to the total amount (100% by mass) of the active ingredient of the target composition. It means that it is less than mass% (preferably less than 0.001 mass%, more preferably less than 0.0001 mass%).

The composition (xβ) preferably further contains a cross-linking agent, and may contain the above-mentioned general-purpose additive as long as it does not affect the value of the strength ratio I (Xβ) of the layer (Xβ). good.
Moreover, the composition (xβ) may contain the above-mentioned fine particles.
However, the content of the fine particles in the composition (xβ) is usually less than 15% by mass, preferably 0 to 13% by mass, more preferably 0 to 13% by mass, based on the total amount (100% by mass) of the active ingredients of the composition (xβ). It is 0 to 10% by mass, more preferably 0 to 5% by mass, and even more preferably 0% by mass.

The content of the adhesive resin in the composition (xβ) is usually 65% by mass or more, preferably 70% by mass or more, more preferably 70% by mass or more, based on the total amount (100% by mass) of the active ingredients of the composition (xβ). 75% by mass or more, more preferably 80% by mass or more, still more preferably 85% by mass or more, and usually 100% by mass or less, preferably 99.9% by mass or less, more preferably 99.0% by mass or less. Is.

In the present invention, in order to adjust the intensity ratio I (Xβ) of the layer (Xβ) to the above-mentioned preferable range to obtain the layer (Xβ) satisfying the requirement (II), it is a material for forming the layer (Xβ). In the composition which is a multi-layer forming material, not only the presence of the tackifier in the composition (xβ) is taken into consideration, but also the migration of the tackifier contained in another layer such as the layer (Xα) is suppressed. It is necessary to consider the ingredients of.
Considering this point, for example, when the layer (Xα) contains a terpene-based tackifier, the adhesive resin in the composition (xβ) preferably contains an acrylic resin.
That is, the adhesive resin contained in the composition (xβ), which is the material for forming the layer (Xβ), is appropriately selected according to the type of the tackifier contained in the layer (Xα). The transfer of the tackifier from Xα) can be suppressed, and the value of the strength ratio I (Xβ) of the layer (Xβ) can be adjusted to be low.

As the acrylic resin contained as the adhesive resin in the composition (xβ), an acrylic resin having a functional group is preferable, and an acrylic copolymer (P) is more preferable.
Details of the "acrylic resin", the "acrylic resin having a functional group" and the "acrylic copolymer (P)" are as described above.

The composition (xβ) preferably contains a cross-linking agent together with an acrylic resin having a functional group, and more preferably contains a cross-linking agent together with the acrylic copolymer (P).
Examples of the cross-linking agent include the above-mentioned ones, but it is preferable to include one or more selected from a metal chelate-based cross-linking agent, an epoxy-based cross-linking agent, and an aziridine-based cross-linking agent.
The content of the cross-linking agent is preferably 0.01 to 15 parts by mass with respect to 100 parts by mass of the acrylic resin (or acrylic copolymer (P)) having a functional group contained in the composition (xβ). It is more preferably 0.1 to 10 parts by mass, and further preferably 0.3 to 7.0 parts by mass.

<Composition (y1) which is a material for forming the layer (Y1)>
In one aspect of the present invention, the composition (y1) which is the material for forming the layer (Y1) may be different from the compositions (xα) and (xβ), but the above-mentioned requirement (III-1) and It is preferable that the composition is appropriately adjusted in the type and content of each component so as to satisfy (III-2).

Further, the adhesive resin contained in the composition (y1), which is the material for forming the layer (Y1), is appropriately selected according to the type of the tackifier contained in the layer (Xα). The tackifier transferred from Xα) is retained in the layer (Y1) to suppress the transfer to the layer (Xβ), and as a result, the value of the intensity ratio I (Xβ) of the layer (Xβ) is adjusted to be low. You can also.
For example, when the layer (Xα) contains a terpene-based tackifier, the composition (y1) preferably contains an acrylic resin as the tacky resin, and preferably contains an acrylic resin having a functional group. Is more preferable, and it is further preferable to contain the acrylic copolymer (P).
The details of the above-mentioned "acrylic resin", "acrylic resin having a functional group" and "acrylic copolymer (P)" are as described above.

When the composition (y1) contains an acrylic resin having a functional group or an acrylic copolymer (P) as the adhesive resin, it is preferable that the composition (y1) further contains a cross-linking agent.
Examples of the cross-linking agent include the above-mentioned ones, but it is preferable to include one or more selected from a metal chelate-based cross-linking agent, an epoxy-based cross-linking agent, and an aziridine-based cross-linking agent.
The content of the cross-linking agent is preferably 0.01 to 15 parts by mass with respect to 100 parts by mass of the acrylic resin (or acrylic copolymer (P)) having a functional group contained in the composition (y1). It is more preferably 0.1 to 10 parts by mass, and further preferably 0.3 to 7.0 parts by mass.

The composition (y1) is the above-mentioned general-purpose additive as long as it does not affect the value of the strength ratio I (Y1) of the layer (Y1) or the value of the strength ratio I of the layers other than the layer (Y1). May be contained.

Further, in one aspect of the present invention, the layer (Y1) is a layer formed from the composition (y1) containing 15 to 100% by mass of fine particles from the viewpoint of forming an adhesive sheet having improved blister resistance. Is preferable.
The composition (y1) may be a composition containing only fine particles without containing an adhesive resin and a tackifier, but is preferably a composition containing fine particles and an adhesive resin.

The content of the fine particles in the composition (y1) is 15 to 100% by mass, more preferably 20 to 95% by mass, more preferably, based on the total amount (100% by mass) of the active ingredients of the composition (y1). Is 25 to 90% by mass, more preferably 30 to 85% by mass, and even more preferably 35 to 80% by mass.
In the composition (y1) in which the content of the fine particles is 100% by mass, the contents of the adhesive resin and the tackifier are both 0% by mass, and the content of the general-purpose additive optionally added is also 0% by mass. It is 0% by mass.

The content of the adhesive resin in the composition (y1) is preferably 0 to 85% by mass, more preferably 1 to 80% by mass, based on the total amount (100% by mass) of the active ingredient of the composition (y1). , More preferably 5 to 75% by mass, still more preferably 10 to 70% by mass, still more preferably 20 to 65% by mass.

In the composition (y1) containing the adhesive resin together with the fine particles, the content of the tackifier is preferably 0 to 150 parts by mass with respect to 100 parts by mass of the adhesive resin in the composition (y1). It is more preferably 0 to 90 parts by mass, more preferably 0 to 60 parts by mass, still more preferably 0 to 45 parts by mass, and even more preferably 0 to 10 parts by mass.
When the content of the tackifier in the composition (y1) is within the above range, the layer (Y1) satisfying the requirements (III-1) and (III-2) can be easily formed. Further, the strength ratio I (Xβ) of the layer (Xβ) can be easily adjusted to the above-mentioned preferable range, and the pressure-sensitive adhesive layer including the layer (Xβ) satisfying the requirement (II) can be formed.

From the above viewpoint, the content ratio of the tackifier contained in the composition (y1) to 100 parts by mass of the tackifier contained in the composition (xα) is preferably 0 to 100 parts by mass. It is preferably 0 to 80 parts by mass, more preferably 0 to 65 parts by mass, and even more preferably 0 to 20 parts by mass.

〔Base material〕
The base material used in the present invention is not particularly limited, and examples thereof include a paper base material, a resin film or a sheet, and a base material obtained by laminating a paper base material with a resin. It can be appropriately selected according to the above.
Examples of the paper constituting the paper base material include thin-leaf paper, medium-quality paper, high-quality paper, impregnated paper, coated paper, art paper, sulfated paper, and glassin paper.
Examples of the resin constituting the resin film or sheet include polyolefin resins such as polyethylene and polypropylene; vinyl chloride such as polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene-vinyl acetate copolymer, and ethylene-vinyl alcohol copolymer. Based resin; polyester resin such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate; polystyrene; acrylonitrile-butadiene-styrene copolymer; cellulose triacetate; polycarbonate; urethane resin such as polyurethane and acrylic modified polyurethane; polymethylpentene; Examples thereof include polysulfone; polyether ether ketone; polyether sulfone; polyphenylene sulfide; polyimide resin such as polyetherimide and polyimide; polyamide resin; acrylic resin; fluorine resin and the like.
Examples of the base material obtained by laminating the paper base material with a resin include laminated paper obtained by laminating the above-mentioned paper base material with a thermoplastic resin such as polyethylene.

Among these base materials, a resin film or sheet is preferable, a film or sheet made of polyester resin is more preferable, and a film or sheet made of polyethylene terephthalate (PET) is further preferable.
When the adhesive sheet of the present invention is used for applications requiring heat resistance, a film or sheet composed of a resin selected from polyethylene naphthalate and a polyimide resin is preferable, and applications requiring weather resistance. A film or sheet composed of a resin selected from polyvinyl chloride, polyvinylidene chloride, acrylic resin, and fluororesin is preferable.

The thickness of the base material is appropriately set according to the use of the pressure-sensitive adhesive sheet of the present invention, but from the viewpoint of handleability and economy, it is preferably 5 to 1000 μm, more preferably 10 to 500 μm, and further preferably 12 to. It is 250 μm, more preferably 15 to 150 μm.
The base material may further contain various additives such as an ultraviolet absorber, a light stabilizer, an antioxidant, an antistatic agent, a slip agent, an antiblocking agent, and a colorant.

Further, the base material used in the present invention is preferably a non-breathable base material from the viewpoint of improving the blister resistance of the obtained pressure-sensitive adhesive sheet, and specifically, a metal on the surface of the above-mentioned resin film or sheet. A base material having a layer is preferable.
Examples of the metal contained in the metal layer include metals having a metallic luster such as aluminum, tin, chromium, and titanium.
As a method for forming the metal layer, for example, a method of vapor deposition of the metal by a PVD method such as vacuum deposition, sputtering, ion plating, or a method of attaching a metal foil made of the metal by a general adhesive is used. Although a method and the like can be mentioned, a method of depositing the above metal by the PVD method is preferable.

Further, when a resin film or sheet is used as the base material, the surface of the resin film or sheet is subjected to an oxidation method or unevenness from the viewpoint of improving the adhesion to the pressure-sensitive adhesive layer laminated on the resin film or sheet. Surface treatment by a chemical method or the like, or primer treatment may be performed.
Examples of the oxidation method include corona discharge treatment, plasma discharge treatment, chromic acid treatment (wet), hot air treatment, ozone, and ultraviolet irradiation treatment, and examples of the unevenness method include a sandblast method and a solvent treatment method. And so on.

[Release material]
Examples of the release material used in the present invention include a release sheet that has undergone double-sided release treatment, a release sheet that has undergone single-sided release treatment, and the like, and a release agent coated on a base material for the release material.
It should be noted that the peeling surface is preferably a flat peeling material (for example, a peeling material without an embossed pattern) on which an uneven shape is not formed.
Examples of the base material for the release material include the above-mentioned paper base material used as the base material of the pressure-sensitive adhesive sheet of one aspect of the present invention, a resin film or sheet, and a base material obtained by laminating a paper base material with a resin. Be done.
Examples of the release agent include rubber-based elastomers such as silicone-based resins, olefin-based resins, isoprene-based resins, and butadiene-based resins, long-chain alkyl-based resins, alkyd-based resins, and fluorine-based resins.
The thickness of the release material is not particularly limited, but is preferably 10 to 200 μm, more preferably 25 to 170 μm, and even more preferably 35 to 80 μm.

[Easy-stick adhesive sheet according to one aspect of the present invention]
As the pressure-sensitive adhesive sheet of one aspect of the present invention, as shown in FIG. 3, the recess 13 and the flat surface 14 are easily present on the surface (α) of the layer (Xα) of the pressure-sensitive adhesive layer 12 which is a multilayer structure. The stickable adhesive sheet 2 may be used.
The recess 13 existing on the surface (α) can serve as an air discharge passage for allowing the “air pool” generated when the surface (α) is attached to the adherend to escape to the outside. Therefore, the easy-to-attach adhesive sheet 2 having the recess 13 on the surface (α) can be excellent in air bleeding property.
Further, the flat surface 14 existing on the surface (α) is a surface that comes into direct contact with and adheres to the adherend at the time of bonding with the adherend, and affects the adhesive strength of the easy-to-attach adhesive sheet 2. It is a place.

FIG. 4 is a schematic surface view of the surface (α) when the pressure-sensitive adhesive layer of the easy-to-attach adhesive sheet according to the present invention is observed from the surface (α) side.
In the easily stickable adhesive sheet of one aspect of the present invention, the recess 13 existing on the surface (α) is an amorphous recess, as shown in FIG. 4, from the viewpoint of making the adhesive sheet excellent in air bleeding property. It is preferable, and it is more preferable that the recess is visually recognizable as an amorphous shape.
Since the surface (α) has irregular recesses, it is possible to prevent all the recesses 13 from being crushed and the air bleeding path disappearing even when pressure is applied from a certain direction.

Further, in the easy-to-attach adhesive sheet of one aspect of the present invention, from the viewpoint of making the adhesive sheet excellent in adhesive properties, as shown in FIG. 4, the flat surface 14 existing on the surface (α) is irregularly flat. It is preferably a surface, and more preferably a flat surface that can be visually recognized as an amorphous surface.

In the present invention, "indeterminate shape" does not have a fixed shape such as a figure capable of drawing a center such as a circle or an ellipse, or a polygon, and the shape has no regularity and is similar to an individual shape. It means that the shape has no property, and specifically, the shape of the recess 13 and the flat surface 14 shown in FIG. 4 corresponds to the shape.
The "polygon" excluded from the indeterminate shape here is a figure in which a diagonal line can be drawn inside (without protruding to the outside), and the sum of the internal angles is 180 × n. (Degree) (n is a natural number) refers to a figure surrounded by a straight line. The polygon also includes a polygon whose corners are curved in a rounded shape.

Further, in order to determine whether or not the concave portion and the flat surface existing on the surface (α) are irregular, the pressure-sensitive adhesive layer of the easy-to-attach adhesive sheet according to one aspect of the present invention is visually or digitally microscoped from the surface (α) side. In principle, the judgment is made by observing with an electron microscope (magnification: 30 to 100 times).
However, 1 to 10 regions (D) of 8 mm in length × 10 mm in width arbitrarily selected on the surface (α) are selected, and the shape of the recess or the flat surface existing in each of the selected regions (D) is used as the surface. Judgment may be made by visually observing from the (α) side or by observing with a digital microscope (magnification: 30 to 100 times). That is, if an amorphous recess or a flat surface is present in any of the selected regions, it can be considered that "an amorphous recess or a flat surface is present on the surface (α)".
In addition, instead of the digital microscope, for example, a line sensor camera may be used to determine "whether or not the concave portion and the flat surface are irregular" in-line. By performing the measurement in-line, it can also serve as an inspection of the product at the time of mass production.

Further, in the easy-to-attach adhesive sheet according to one aspect of the present invention, the area ratio of the flat surface existing on the surface (α) to 100% of the total area of the surface (α) is preferably 20 to 95%. It is preferably 30 to 90%, more preferably 40 to 85%, and even more preferably 45 to 80%.

For the above-mentioned "area ratio occupied by a flat surface", an image of the surface (α) is acquired using a digital microscope (magnification: 30 to 100 times), and image processing (binarization processing) is performed on the image. ) Can be calculated.
Further, 1 to 10 areas (D) of 8 mm in length × 10 mm in width arbitrarily selected on the surface (α) are selected, and an image of the area is obtained using a digital microscope (magnification: 30 to 100 times). The value of the "area ratio occupied by the flat surface" of each region is calculated from the acquired image, and the average of the values in the selected 1 to 10 regions is calculated as the surface (α) of the pressure-sensitive adhesive layer of the target pressure-sensitive adhesive sheet. It can also be regarded as the "area ratio occupied by the flat surface" that exists in.
Instead of the digital microscope, for example, a line sensor camera may be used to measure the "area ratio occupied by the flat surface" in-line.

In the easy-to-attach adhesive sheet of one aspect of the present invention, from the viewpoint of forming an adhesive sheet having an excellent balance between air bleeding property and adhesive properties, the concave portion and the flat surface existing on the surface (α) are peeled off having an embossed pattern. It is preferable that it is not formed by using a material.
Specifically, the concave portion and the flat surface existing on the surface (α) are preferably formed by self-forming the pressure-sensitive adhesive layer. That is, it is preferable that the recess and the flat surface are formed as a by-product when the pressure-sensitive adhesive layer is formed in the process of self-forming the pressure-sensitive adhesive layer.
The recesses and flat surfaces formed by the self-formation of the pressure-sensitive adhesive layer tend to be recesses or flat surfaces that can be visually recognized as irregular.

In particular, in the easy-to-attach adhesive sheet according to one aspect of the present invention, the concave portion and the flat surface existing on the surface (α) are the layer (Xβ) formed from the above-mentioned composition (xβ) and the above-mentioned fine particles from 15 to 15. A pressure-sensitive adhesive layer which is a multilayer structure formed by laminating a layer (Y1) formed from a composition (y1) containing 100% by mass and a layer (Xα) formed from the above-mentioned composition (xα) in this order. It is preferably formed by self-formation of.

In the present invention, "self-forming" means a phenomenon that naturally creates a disordered shape in the process of autonomous formation of the pressure-sensitive adhesive layer, and more specifically, from a composition that is a material for forming the pressure-sensitive adhesive layer. It means a phenomenon in which the formed coating film is dried to naturally create a disordered shape in the process of autonomous formation of the pressure-sensitive adhesive layer.

Further, as in the easy-to-attach adhesive sheet 2 shown in FIG. 3, in the process of self-forming the pressure-sensitive adhesive layer 12, an amorphous recess 13 is likely to be formed on the surface (α) 12a of the layer (Xα). With the formation of the recess 13, the thickness of each layer tends to be more non-uniform.
The process of forming the pressure-sensitive adhesive layer and the recesses having a non-uniform thickness of each layer formed by the self-formation of the pressure-sensitive adhesive layer is considered as follows.
First, in the process of forming at least two pressure-sensitive adhesive layers, which are different constituents, shrinkage stress is generated inside the coating film in the step of drying a plurality of coating films formed from different compositions. At the portion where the binding force of the resin is weakened, the constituent components move within the plurality of coating films, and further, cracks occur on the surface (α). Then, the thickness of each layer becomes non-uniform due to the further movement of the constituent components to the moved portion of the constituent components, and the resin existing around the cracked portion is cracked. It is considered that a recess is formed on the surface (α) of the pressure-sensitive adhesive layer by flowing into the temporarily generated space.
That is, since a large-scale movement of the resin occurs at the same time as the formation of the concave portion, the thickness of each layer becomes more uneven, and the layer (Xα), the layer (Y1), and the layer (Xβ) satisfying the above requirements are formed. easy.
By forming two layers of coating film with different resin constituents and then drying the two layers of coating film at the same time, a shrinkage stress difference occurs inside the coating film during drying, and the thickness of each layer is not sufficient. It is considered that the surface (α) becomes uniform and cracks are likely to occur on the surface (α).

For example, on the surface (α) of the pressure-sensitive adhesive layer of the easy-to-attach adhesive sheet 2 shown in FIG. 3, at least a coating film (xα') composed of a composition (xα) which is a material for forming the layer (Xα) is formed. By self-forming, which simultaneously dries the coating film (y1') composed of the composition (y1), which is the material for forming the layer (Y1), to naturally create a disordered shape in the autonomous formation process of the pressure-sensitive adhesive layer. It is preferable that the formed recess is present.

From the viewpoint of forming a recess on the surface (α) and facilitating the formation of the layer (Xα), the layer (Y1) and the layer (Xβ) satisfying the above requirements, the following items may be appropriately considered and adjusted. preferable. It is considered that the factors due to these matters act in a complex manner to facilitate the formation of recesses, and facilitate the formation of layers (Xα), layers (Y1) and layers (Xβ) satisfying the above requirements.
-Type, constituent monomer, molecular weight, and content of the resin contained in the composition that is the material for forming the coating film.
-Types of cross-linking agents and solvents contained in the composition that is the material for forming the coating film.
-Viscosity and solid content concentration of the composition that forms the coating film.
-Thickness of the coating film to be formed. (In the case of multiple layers, the thickness of each coating film)
-Drying temperature and drying time of the formed coating film.

The above items are preferably set as appropriate in consideration of the fluidity of the resin contained in the formed coating film and the like.
For example, when the composition contains fine particles, the viscosity of the coating film composed of the composition containing a large amount of fine particles is adjusted to an appropriate range, so that the predetermined fluidity of the fine particles in the coating film can be maintained. Mixing with other coating films (coating films containing a large amount of resin) can be appropriately suppressed. By adjusting in this way, in the coating film containing a large amount of resin, cracks occur in the horizontal direction and recesses are likely to be formed, so that the layer (Xα), the layer (Y1) and the layer (Xβ) satisfying the above requirements can be formed. It tends to be formed.

Further, among the above items, it is preferable to appropriately adjust the type, constituent monomer, molecular weight, and resin content of the resin so that the resin contained in the coating film containing a large amount of resin has appropriate viscoelasticity.
That is, by appropriately increasing the hardness of the coating film (hardness determined by factors such as the viscoelasticity of the resin and the viscosity of the coating liquid), the shrinkage stress of the resin portion becomes stronger, and recesses are more likely to be formed. A layer (Xα), a layer (Y1) and a layer (Xβ) satisfying the above requirements are formed.
The harder the coating film is, the stronger the shrinkage stress is, and recesses are likely to occur, but if it is too hard, the coating suitability is lowered. Further, if the elasticity of the resin is increased too much, the adhesive strength of the pressure-sensitive adhesive layer formed from the coating film tends to decrease. In consideration of this point, it is preferable to appropriately adjust the viscoelasticity of the resin.
Further, when fine particles are contained in the composition or the coating film, by adjusting the dispersed state of the fine particles, the degree of swelling of the thickness of the pressure-sensitive adhesive layer due to the fine particles and the self-forming force of the recesses can be adjusted. It is considered that the layer (Xα), the layer (Y1), and the layer (Xβ) satisfying the above-mentioned requirements are formed by adjusting so that a recess is easily formed on the surface (α).

Further, it is preferable to appropriately set the above items in consideration of the crosslinking rate of the formed coating film (or the composition which is the forming material).
That is, if the cross-linking speed of the coating film is too high, the coating film may be cured before the recesses are formed. It also affects the size of cracks in the coating film.
The cross-linking rate of the coating film can be adjusted by appropriately setting the type of the cross-linking agent and the type of the solvent in the composition as the forming material, and the drying time and the drying temperature of the coating film.

<Specific formulation that facilitates the formation of irregular recesses on the surface (α)>
As a more specific formulation, by using a composition (xα), (y1), and (xβ) that satisfy the following items, the surface (α) is formed in the process of self-formation of the pressure-sensitive adhesive layer. Atypical recesses are likely to be formed.

(1) Selection of Adhesive Resin in Each Composition The compositions (xα), (y1), and (xβ) preferably contain an acrylic resin or a rubber-based resin as the adhesive resin, and are acrylic-based. It is more preferable to contain a resin.
The acrylic resin preferably contains the above-mentioned acrylic resin having a functional group, and more preferably contains the above-mentioned acrylic copolymer (P). The details of the acrylic resin, the acrylic resin having a functional group, and the acrylic copolymer (P) are as described above.

(2) Selection of cross-linking agent in each composition The cross-linking agent in the compositions (xα), (y1), and (xβ) together with an acrylic resin (or an acrylic copolymer (P)) having a functional group. Is preferably contained.
The cross-linking agent contained in the compositions (xα), (y1), and (xβ) is a metal chelate from the viewpoint of facilitating the formation of irregular recesses and flat surfaces on the surface (α) of the pressure-sensitive adhesive layer. It is preferable to contain one or more selected from a system-based cross-linking agent, an epoxy-based cross-linking agent, and an aziridine-based cross-linking agent, more preferably a metal chelate-based cross-linking agent, and further preferably an aluminum chelate-based cross-linking agent.

Further, from the viewpoint of facilitating the formation of irregular recesses on the surface (α) of the pressure-sensitive adhesive layer, a metal chelate-based cross-linking agent and an epoxy-based cross-linking agent are added to the composition (xα) which is a material for forming the layer (Xα). It is preferable to include both.
When both the metal chelate-based cross-linking agent and the epoxy-based cross-linking agent are contained, the content ratio of the metal chelate-based cross-linking agent to the epoxy-based cross-linking agent in the composition (xα) [metal chelate-based cross-linking agent / epoxy-based cross-linking agent] , More preferably 10/90 to 99.5 / 0.5, more preferably 50/50 to 99.0 / 1.0, still more preferably 65/35 to 98.5 / 1.5, in terms of mass ratio. More preferably, it is 75/25 to 98.0 / 2.0.

(3) Selection of Fine Particles in Composition (y1) The composition (y1) contains silica particles as fine particles from the viewpoint of facilitating the formation of amorphous recesses on the surface (α) of the pressure-sensitive adhesive layer. Is preferable.
The content of the silica particles in the composition (y1) is preferably 15 to 100% by mass, more preferably 20 to 95% by mass, based on the total amount (100% by mass) of the active ingredient of the composition (y1). It is preferably 25 to 90% by mass, more preferably 30 to 85% by mass, and even more preferably 35 to 80% by mass.

The mass concentration of silica in the silica particles is preferably 70 to 100% by mass, more preferably 85 to 100% by mass, still more preferably, based on the total amount (100% by mass) of the silica particles in the composition (y1). It is 90 to 100% by mass.

Further, the volume average secondary particle diameter of the silica particles used in one aspect of the present invention is determined from the viewpoint of improving the air bleeding property and blister resistance of the pressure-sensitive adhesive sheet, and the surface (α) of the pressure-sensitive adhesive layer has a recess and a flat surface. From the viewpoint of facilitating the formation of the above, it is preferably 0.5 to 10 μm, more preferably 1 to 8 μm, and further preferably 1.5 to 5 μm.
In the present invention, the value of the volume average secondary particle diameter of the silica particles is a value obtained by measuring the particle size distribution by the Coulter counter method using a multisizer / three machine or the like.

Here, as the fine particles, the pressure-sensitive adhesive layer formed by using fine particles such as silica particles in which a plurality of particles aggregate to form secondary particles tends to include void portions. The presence of voids in the pressure-sensitive adhesive layer can improve the blister resistance of the pressure-sensitive adhesive sheet.
The void portion also includes voids existing between the fine particles and, when the fine particles are secondary particles, voids existing in the secondary particles.
Even if there are voids in the process of forming the pressure-sensitive adhesive layer, which is a multilayer structure, or immediately after the formation, the adhesive resin or the like flows into the voids, the voids disappear, and the adhesive has no voids. It may be a drug layer.
However, even when the void portion that has existed for a while in the pressure-sensitive adhesive layer disappears in this way, the easy-to-stick pressure-sensitive adhesive sheet according to one aspect of the present invention has a recess in the surface (α) of the pressure-sensitive adhesive layer. Therefore, the air bleeding property is good, and if the fine particles are present in the pressure-sensitive adhesive layer, the blister resistance is also excellent.

(Mass retention of adhesive layer)
The mass retention of the pressure-sensitive adhesive layer of the easy-to-stick pressure-sensitive adhesive sheet according to one aspect of the present invention after heating at 800 ° C. for 30 minutes is 3 to 90% by mass (more preferably 5 to 80% by mass, still more preferably 7 to 7 to 7 to 80% by mass). 70% by mass, more preferably 9 to 60% by mass).
When the mass retention rate is 3% by mass or more, it can be an adhesive sheet having excellent air bleeding property and blister resistance. Further, during the production of the pressure-sensitive adhesive sheet of the present invention, recesses are likely to be formed on the surface (α) of the pressure-sensitive adhesive layer. On the other hand, when the mass retention rate is 90% by mass or less, the film strength of the pressure-sensitive adhesive layer is high, water resistance and chemical resistance are excellent, and a flat surface is likely to be formed on the surface (α) of the pressure-sensitive adhesive layer.
The mass retention rate can be regarded as indicating the content (mass%) of the fine particles contained in the pressure-sensitive adhesive layer, and can be adjusted by changing the content of the fine particles contained in each composition. ..

<Distribution of fine particles in the adhesive layer>
In the easy-to-apply adhesive sheet of one aspect of the present invention, in the pressure-sensitive adhesive layer having recesses formed by self-formation of the pressure-sensitive adhesive layer, the recesses 13 are present on the surface (α) as shown in FIG. The proportion of the fine particles 15 present at the location tends to be smaller than the proportion of the fine particles 15 present at the location where the flat surface 14 is present on the surface (α).
This is because, in the process of self-forming the pressure-sensitive adhesive layer, when the recess is formed on the surface (α) of the pressure-sensitive adhesive layer, the fine particles existing at the position where the recess is formed move. It is considered that the distribution is as follows.

The shape of the recess formed by the self-formation of the pressure-sensitive adhesive layer as described above can be adjusted to some extent by adjusting the drying conditions and the type and content of the components in the composition which is the material for forming the pressure-sensitive adhesive layer. However, unlike the groove formed by using a release material having an embossed pattern, it can be said that "it is virtually impossible to reproduce exactly the same shape".
Therefore, the shape of the concave portion 13 tends to be irregular, and the shape of the flat surface 14 is also irregular due to the formation of the irregular concave portion on the surface (α).

[Method for Manufacturing Adhesive Sheet of the Present Invention]
The method for producing the pressure-sensitive adhesive sheet of the present invention is not particularly limited, and a coating film composed of each composition which is a material for forming the pressure-sensitive adhesive layer which is a multilayer structure is formed on a base material, and the coating film is dried. It can be manufactured by forming each layer.

For example, as a method for producing the pressure-sensitive adhesive sheet 1a shown in FIG. 1A, a layer (Xβ) is formed on the base material 11 using the composition (xβ), and then the composition is formed on the layer (Xα). Examples thereof include a manufacturing method having a step of forming a layer (Xα) using an object (xα).
In the above production method, a coating film (xβ') composed of the composition (xβ) and a coating film (xα') composed of the composition (xα) are formed on the base material 11, and then these coatings are applied. The membrane may be dried simultaneously to form a layer (Xβ) and a layer (Xα) at the same time.
Further, in the pressure-sensitive adhesive sheet 1a shown in FIG. 1A, a layer (Xβ) formed by using the composition (xβ) on the base material 11 and a composition (xα) prepared separately on a release material are formed. It can also be produced by attaching the layer (Xα) formed in use.

Further, as a method for producing the pressure-sensitive adhesive sheet 1b shown in FIG. 1B, a layer (Xβ) is formed on the base material 11 by using the composition (xβ), and the composition (y1) is formed on the layer (Xβ). A production method including a step of forming a layer (Y1) using the above-mentioned material and forming a layer (Xα) on the layer (Y1) using the composition (xα) can be mentioned.
Also in the above method for producing the pressure-sensitive adhesive sheet 1b, the coating film (xβ') composed of the composition (xβ), the coating film (y1') composed of the composition (y1), and the composition (xα) are placed on the base material 11. After forming the coating film (xα') composed of), these coating films may be dried at the same time to form the layer (Xβ), the layer (y1) and the layer (Xα) at the same time.
Further, it is also possible to form the layer (Xβ), the layer (y1) and the layer (Xα) separately, and then attach them in order for production.

When forming the coating film, in order to facilitate the formation of the coating film, it is preferable to further add a solvent to the composition which is a material for forming each layer to form a solution of the composition.
Examples of such a solvent include water, an organic solvent and the like.
Examples of the organic solvent include toluene, ethyl acetate, butyl acetate, methyl ethyl ketone, methyl isobutyl ketone, methanol, ethanol, isopropyl alcohol, t-butanol, s-butanol, acetylacetone, cyclohexanone, n-hexane, cyclohexane and the like. .. These solvents may be used alone or in combination of two or more.

As a coating method on the base material or the release material, a known method can be used.
Further, as a method of forming a plurality of coating films, a method of sequentially forming one coating film and then forming another door film on the formed coating film may be used, and a plurality of coating films may be formed by a multilayer coater. May be used at the same time to form the film.
Examples of the coater used for sequential formation include a spin coater, a spray coater, a bar coater, a knife coater, a roll coater, a knife roll coater, a blade coater, a gravure coater, a curtain coater, and a die coater.
Examples of the coater used for simultaneous coating with the multi-layer coater include a curtain coater and a die coater. Among these, the die coater is preferable from the viewpoint of operability.

[Method for manufacturing an easily stickable adhesive sheet according to one aspect of the present invention]
The method for producing an easily stickable pressure-sensitive adhesive sheet according to one aspect of the present invention is not particularly limited, but is formed from the viewpoint of productivity and on the surface (α) of the pressure-sensitive adhesive layer by self-formation of the pressure-sensitive adhesive layer. From the viewpoint of making it easier to form the concave portion and the flat surface, the production method of the first aspect having at least the following steps (1A) and (2A), or the second having at least the following steps (1B) and (2B). The production method according to the above embodiment is preferable.

Production method of the first aspect: A method for producing an easy-to-stick adhesive sheet, which comprises at least the following steps (1A) and (2A).
Step (1A): A coating film (xβ') composed of the composition (xβ), a coating film (y1') composed of the composition (y1) containing 15% by mass or more of the fine particles, and the composition on the substrate. Step / Step (2A): The coating film (xβ') formed in the step (1A), the coating film (y1'), and the coating film (xα') formed by laminating the coating film (xα') composed of (xα) in this order. Step to dry the membrane (xα') at the same time

Method for producing a second aspect: A method for producing an easy-to-attach adhesive sheet, which comprises at least the following steps (1B) and (2B).
Step (1B): A coating film (y1 ′) composed of the composition (y1) containing 15% by mass or more of the fine particles on a layer (Xβ) formed by using the composition (xβ) provided on the substrate. ), And the coating film (xα') composed of the composition (xα) are laminated in this order to form the coating film (xα'): the coating film (y1') and the coating film (xα') formed in the step (1B). ') The process of drying at the same time

The details of the composition (xβ), the composition (y1), and the composition (xα) used in the step (1A) and the step (1B) are as described above.

When forming the coating film, it is preferable to add a solvent to the composition (xβ), (xα) and (y1) to form a solution of the composition in order to facilitate the formation of the coating film. ..
Examples of such a solvent include water, an organic solvent, and the like, and the organic solvents that can be used are as described above.

As a method for forming the coating films (xβ'), (y1'), and (xα'), each coating film may be formed sequentially, and from the viewpoint of productivity, each coating film may be simultaneously formed by a multilayer coater. The method of coating and forming may also be used.
The coater used for sequential formation and the coater used for simultaneous coating with the multilayer coater are as described above.

(Manufacturing method of the first aspect)
In the step (1A), it is preferable that the composition (xβ), the composition (y1), and the composition (xα) are blended with the above-mentioned solvent to form a solution of the composition, and then applied.
As a method for forming the coating film (xβ'), the coating film (y1'), and the coating film (xα'), after forming the coating film (xβ') on the substrate, the coating film (xβ') is formed. A coating film (y1') is formed on the coating film (y1'), and a coating film (xα') is further formed on the coating film (y1'). A method of simultaneously coating and forming the'), the coating film (y1') and the coating film (xα') using the above-mentioned multilayer coater may also be used.

The coating amount of the coating film (xα'), the coating film (y1'), and the coating film (xβ') is preferably 1.5 to 800 g / m ^{2 from the viewpoint of improving air bleeding property and adhesive properties.} preferably 5 to 500 g / ^{m 2,} more preferably 10 to 300 g / ^{m 2,} even more preferably from 20 to 200 g / ^{m 2.}

The ratio of the coating amount of the coating film (y1') to the coating amount of the coating film (xα') is preferably 5 to 2000, more preferably 50 to 1500, from the viewpoint of improving air bleeding property and adhesive properties. , More preferably 100 to 1000.

In this step (1A), after forming one or more coating films of the coating film (xβ'), the coating film (y1'), and the coating film (xα'), before moving to the step (2A). Pre-drying treatment may be performed to the extent that the curing reaction of the coating film does not proceed.
For example, after each coating film of the coating film (xβ'), the coating film (y1'), and the coating film (xα') is formed, the above pre-drying treatment may be performed each time, and the coating film (xβ') may be performed. ) And the coating film (y1'), and then the above-mentioned pre-drying treatment is collectively performed, and then the coating film (xα') may be formed.
The drying temperature at the time of performing the pre-drying treatment in this step (1A) is usually set appropriately within a temperature range in which curing of the formed coating film does not proceed, but is preferably set in step (2A). It is below the drying temperature of. The specific drying temperature indicated by the definition of "less than the drying temperature in step (2A)" is preferably 10 to 45 ° C, more preferably 10 to 34 ° C, and even more preferably 15 to 30 ° C.

The step (2A) is a step of simultaneously drying the coating film (xβ'), the coating film (y1'), and the coating film (xα') formed in the step (1A).
The drying temperature in this step is preferably 35 to 200 ° C., more preferably 60 to 180 ° C., still more preferably 70 to 160, from the viewpoint of facilitating the formation of recesses and flat surfaces on the surface (α) of the pressure-sensitive adhesive layer. ° C., more preferably 80-140 ° C.

(Manufacturing method of the second aspect)
As a method for forming the layer (Xβ), a coating film (xβ') composed of the composition (xβ) can be formed on the substrate, and the coating film (xβ') can be dried to form the layer (Xβ).
The drying temperature at this time is not particularly limited, and is preferably 35 to 200 ° C., more preferably 60 to 180 ° C., still more preferably 70 to 160 ° C., and even more preferably 80 to 140 ° C.

In this embodiment, the coating film (y1') and the coating film (xα') are formed in this order not on the coating film (xβ') but on the layer (Xβ) obtained after drying. , Different from the first aspect described above.
Also in the step (1B), it is preferable to add the above-mentioned solvent to the composition (y1) and the composition (xα) to form a solution of the composition, and then apply the mixture.
As a method for forming the coating film (y1') and the coating film (xα'), after forming the coating film (y') on the layer (Xβ), the coating film (xα') is formed on the coating film (y1'). ) May be formed sequentially using the above-mentioned coater, or the coating film (y1') and the coating film (xα') may be simultaneously applied and formed using the above-mentioned multilayer coater. good.

The ratio of the coating amount of the coating film (xα') and the coating film (y1') and the coating amount of the coating film (y1') to the coating amount 100 of the coating film (xα') is determined by the production method of the first aspect. It is the same as the step (1A).

In this step (1B), after the coating film (y1') is formed, or after the coating film (y1') and the coating film (xα') are formed, before moving to the step (2B), the coating film of the coating film is used. Pre-drying treatment may be performed to the extent that the curing reaction does not proceed.
The drying temperature at the time of performing the pre-drying treatment in this step (1B) is usually set appropriately within a temperature range at which curing of the formed coating film does not proceed, but is preferably set in step (2B). It is below the drying temperature of. The specific drying temperature indicated by the definition of "less than the drying temperature in step (2B)" is preferably 10 to 45 ° C, more preferably 10 to 34 ° C, and even more preferably 15 to 30 ° C.

The step (2B) is a step of simultaneously drying the coating film (y1') and the coating film (xα') formed in the step (1B).
The drying temperature in this step is preferably 35 to 200 ° C., more preferably 60 to 180 ° C., still more preferably 70 to 160, from the viewpoint of facilitating the formation of recesses and flat surfaces on the surface (α) of the pressure-sensitive adhesive layer. ° C., more preferably 80-140 ° C.

The present invention will be specifically described with reference to the following examples, but the present invention is not limited to the following examples. The physical property values in the following production examples and examples are values measured by the following methods.

<Mass average molecular weight (Mw)>
It was measured under the following conditions using a gel permeation chromatograph device (manufactured by Tosoh Corporation, product name "HLC-8020"), and the value measured in terms of standard polystyrene was used.
(Measurement condition)
-Column: "TSK guard volume HXL-L""TSK gel G2500HXL""TSK gel G2000HXL""TSK gel G1000HXL" (all manufactured by Tosoh Corporation) are connected in sequence.-Column temperature: 40 ° C.
-Development solvent: tetrahydrofuran-Flow velocity: 1.0 mL / min

<Measurement of volume average secondary particle size of silica particles>
The volume average secondary particle size of the silica particles was determined by measuring the particle size distribution by the Coulter counter method using a multisizer three machine (manufactured by Beckman Coulter).

<Measurement of adhesive layer thickness>
The measurement was performed using a constant pressure thickness measuring instrument (model number: "PG-02J", standard: JIS K6783, Z1702, Z1709 compliant) manufactured by Teclock Co., Ltd.
Specifically, after measuring the total thickness of the pressure-sensitive adhesive sheet to be measured, the value obtained by subtracting the thickness of the base material or the release sheet measured in advance was defined as the "thickness of the pressure-sensitive adhesive layer".

Production example x-1 to x-5
(Preparation of solutions of resin composition (xβ-1) to (xβ-3) and (xα-1) to (xα-2))
To the solution of the acrylic resin which is the adhesive resin of the type and the solid content shown in Table 1, the cross-linking agent and the tackifier of the type and the blending amount shown in Table 1 were added. Then, it is further diluted with the diluting solvent shown in Table 1, and the solutions (xβ-1) to (xβ-3) and (xα-1) to (xα-1) of the resin composition having the solid content concentration shown in Table 1 are further diluted. xα-2) were prepared respectively.

The details of each component shown in Table 1 used for preparing the solutions (xβ-1) to (xβ-3) and (xα-1) to (xα-2) of the resin composition are as follows. ..
<Acrylic resin solution>
Solution (i): Contains acrylic resin (x-i) (acrylic copolymer having a structural unit derived from a raw material monomer composed of BA / AA = 90/10 (mass%), Mw: 470,000). A mixed solution of toluene and ethyl acetate having a solid content concentration of 37.0% by mass.
-Solution (ii): Acrylic copolymer having a structural unit derived from a raw material monomer composed of an acrylic resin (x-ii) (2EHA / VAc / AA = 75/23/2 (mass%), Mw: 66. A mixed solution of toluene and ethyl acetate having a solid content concentration of 37.0% by mass containing (10,000).
Solution (iii): An acrylic copolymer having a structural unit derived from a raw material monomer composed of an acrylic resin (x-iii) (2EHA / BA / VAc / AA = 70/20/5/5 (mass%)). , Mw: 630,000), a mixed solution of toluene and ethyl acetate having a solid content concentration of 33.5% by mass.
-Solution (iv): Acrylic copolymer having a structural unit derived from a raw material monomer composed of an acrylic resin (x-iv) (BA / AA / HEA = 94/3/3 (mass%), Mw: 100. A mixed solution of toluene and ethyl acetate having a solid content concentration of 37.0% by mass containing (10,000).
The abbreviations of the raw material monomers constituting the above-mentioned acrylic copolymer are as follows.
-BA: n-butyl acrylate-2EHA: 2-ethylhexyl acrylate-AA: acrylic acid-VAc: vinyl acetate-HEA: hydroxyethyl acrylate

<Crosslinking agent>
-Al-based cross-linking agent: Product name "M-5A", manufactured by Soken Kagaku Co., Ltd., aluminum chelate-based cross-linking agent, solid content concentration = 4.95% by mass.
-Epoxy-based cross-linking agent: A solution of an epoxy-based cross-linking agent obtained by diluting "TETRAD-C" (product name, manufactured by Mitsubishi Gas Chemical Company, Ltd.) with toluene to obtain a solid content concentration of 5% by mass.

<Adhesive imparting agent>
-Rosin ester-based TF: Rosin ester-based tackifier, Mw: less than 10,000, softening point: 135 ° C.
-Styrene-based TF: Styrene-based tackifier, Mw: less than 10,000, softening point: 95 ° C.
-Terpene-based TF: Aromatically modified terpene-based tackifier, Mw: less than 10,000, softening point: 115 ° C.
-Hydrogenated terpene-based TF: Hydride of aromatic-modified terpene-based tackifier, Mw: less than 10,000, softening point: 100 ° C.

<Diluting solvent>
-Mixed solvent (1): A mixed solvent prepared by mixing toluene / isopropyl alcohol (IPA) = 35/65 (mass ratio).
-Mixed solvent (2): A mixed solvent prepared by mixing with ethyl acetate / IPA = 86/14 (mass ratio).
-Mixed solvent (3): A mixed solvent prepared by mixing with toluene / IPA = 40/60 (mass ratio).

Production example f-1
(Preparation of fine particle dispersion (f-1))
An acrylic copolymer (Mw: 470,000) having a structural unit derived from a raw material monomer composed of the above-mentioned solution (i) containing an acrylic resin (x-i) (BA / AA = 90/10 (mass%)). A mixed solution of toluene and ethyl acetate having a solid content concentration of 37.0% by mass) was used.
Silica particles (product name "Nipseal E-200A", manufactured by Toso Silica Co., Ltd., volume average secondary particle diameter) as fine particles with respect to 100 parts by mass (solid content: 37.0 parts by mass) of the solution (i). : 3 μm) was added with 55.5 parts by mass (solid content: 55.5 parts by mass) and toluene to disperse the fine particles, and the solid content concentration of 30 mass including the acrylic resin (xi) and silica particles was added. % A fine particle dispersion (f-1) was prepared.

Production example y-1 to y-3
(Preparation of coating liquids (y-1) to (y-3) for forming a coating film (y1'))
A coating film (y1') having a solid content concentration shown in Table 2 is formed by adding a fine particle dispersion liquid of the type and blending amount shown in Table 2, a solution of an acrylic resin, a cross-linking agent, a tackifier and a diluting solvent. Each of the coating solutions (y-1) to (y-3) of the composition for use was prepared.

The details of each component shown in Table 2 used for preparing the coating liquids (y-1) to (y-3) of the composition for forming the coating film (y1') are as follows.
<Particle dispersion liquid>
Dispersion liquid (f-1): A fine particle dispersion liquid (f-1) having a solid content concentration of 30% by mass, which contains an acrylic resin (xi) and silica particles, prepared in Production Example f-1.
<Acrylic resin solution>
Solution (i): Contains acrylic resin (x-i) (acrylic copolymer having a structural unit derived from a raw material monomer composed of BA / AA = 90/10 (mass%), Mw: 470,000). A mixed solution of toluene and ethyl acetate having a solid content concentration of 37.0% by mass.
<Crosslinking agent>
-Al-based cross-linking agent: Product name "M-5A", manufactured by Soken Kagaku Co., Ltd., aluminum chelate-based cross-linking agent, solid content concentration = 4.95% by mass.
<Adhesive imparting agent>
-Rosin ester-based TF: Rosin ester-based tackifier, Mw: less than 10,000, softening point: 135 ° C.
-Terpene-based TF: Aromatically modified terpene-based tackifier, Mw: less than 10,000, softening point: 115 ° C.
-Hydrogenated terpene-based TF: Hydride of aromatic-modified terpene-based tackifier, Mw: less than 10,000, softening point: 100 ° C.
-Styrene-based TF: Styrene-based tackifier, Mw: less than 10,000, softening point: 95 ° C.
<Diluting solvent>
-Mixed solvent (4): IPA / CHN: A mixed solvent composed of isopropyl alcohol (IPA) and cyclohexanone (CHN) (IPA / CHN = 95/5 (mass ratio)).

Examples 1-3, Comparative Example 1
(1) Formation of coating film A polyethylene terephthalate (PET) film (manufactured by Lintec Corporation, product name "FNS Keshi N50", thickness 50 μm) having an aluminum vapor deposition layer on one side was used as a base material.
On the aluminum vapor-deposited layer of the PET film, any of the solutions (xβ-1) to (xβ-3) of the resin composition prepared in Production Examples x-1 to x-3 shown in Table 3 and Table 3 show. The production example described in Table 3 with any of the coating liquids (y-1) to (y-3) of the composition for forming the coating film (y1') prepared in y-1 to y-3. Table 3 shows any of the resin composition solutions (xα-1) to (xα-2) prepared in x-4 to x-5 in this order using a multilayer die coater (width: 250 mm). The coating film (xβ'), the coating film (y1') and the coating film (xα') were formed at the same time by applying at the described coating rate at the same time.
The coating amounts of the coating film (xβ'), the coating film (y1'), and each solution (coating liquid) for forming the coating film (xα') are as shown in Table 3.

(2) Drying Treatment The formed three-layer coating film (xβ'), coating film (y1') and coating film (xα') are simultaneously dried at a drying temperature of 100 ° C. for 2 minutes to form a layer (Xβ). , The layer (Y1) and the layer (Xα) were laminated in this order to form a pressure-sensitive adhesive layer, which is a multi-layer structure. The thickness of the formed pressure-sensitive adhesive layer is as shown in Table 3.
Then, it is laminated on the surface (α) of the formed pressure-sensitive adhesive layer so as to be bonded to the peeling-treated surface of the release film (manufactured by Lintec Corporation, product name "SP-PET38131"), which is a release material, and has a base material. An adhesive sheet was prepared.

Using the pressure-sensitive adhesive sheet with a base material produced in Examples and Comparative Examples, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet and the characteristics of the pressure-sensitive adhesive sheet were calculated, measured, or observed by the following methods. These results are shown in Table 4.

<Method of calculating the strength ratio I of each layer constituting the adhesive layer>
The strength ratio I of each layer constituting the pressure-sensitive adhesive layer was calculated by the following procedure.
(I) Measurement of Raman Spectrum (Ra) The pressure-sensitive adhesive sheet prepared in Examples and Comparative Examples was allowed to stand for 7 days in an environment of 23 ° C. and 50% relative humidity, and then the pressure-sensitive adhesive sheet shown in FIG. It was installed in the same way as 1.
Then, as shown in FIG. 2, the surface (α) is viewed from the surface (β) 12b side with respect to the cross section 121 of the pressure-sensitive adhesive layer (hereinafter referred to as “adhesive layer (a)”) in the pressure-sensitive adhesive sheet with the base material. ) Toward the 12a side, along the direction P, while shifting the measurement position at regular intervals selected from the range of 0.5 to 1 μm, the laser irradiation device 50 irradiates the excitation laser 51 in the vertical direction, and each measurement is performed. The Raman spectrum (Ra) of the pressure-sensitive adhesive layer (a) at the position was measured.
Each measurement position was set based on an optical microscope image obtained by observing the cross section 121 of the pressure-sensitive adhesive layer 12 using an optical microscope built in the laser irradiation device.
Further, the boundary between the two adjacent layers of the layer (Xβ), the layer (Y1), and the layer (Xα) constituting the pressure-sensitive adhesive layer (a) is the pressure-sensitive adhesive layer used when designating the measurement position. It was identified from the optical microscope image of the cross section 121 of 12 and the obtained Raman spectrum (Ra).

The equipment and measurement conditions used to measure the Raman spectrum are shown below.
-Laser irradiation device: manufactured by Thermo Fisher Scientific Co., Ltd., product name "Nicolet Almega XR"
-Laser wavelength: 532 nm
・ Aperture: 25 μm pinhole ・ Lens magnification: 50 times ・ Output: 100%
・ Exposure time: 2 seconds ・ Number of exposures: 4 times

(Ii) Measurement of Raman spectrum (Rb) In each of the Examples and Comparative Examples, the pressure-sensitive adhesive layer containing no pressure-sensitive adhesive layer was the same as the method for forming the pressure-sensitive adhesive layer (a) except that the pressure-sensitive adhesive was removed. An adhesive sheet having (b) was produced.
Then, the Raman spectrum (Rb) of the pressure-sensitive adhesive layer (b) was measured at an arbitrary position on the cross section of the pressure-sensitive adhesive layer (b) by Raman spectroscopy under the above-mentioned measurement conditions.

(Iii) Calculation of peak height of peak derived from tackifier For Raman spectra (Ra) and (Rb), Raman scattering intensity was compared for each Raman shift.
Specifically, the Raman scattering intensity of a peak of the Raman scattering intensity, the same Raman shift of a Raman spectrum (Rb) (r) of the peak (p _a) of a specific Raman shift (r) of the Raman spectra (Ra) If the ten-fold, was the peak of the Raman spectrum (Ra) and (p _a) determines that the "peak derived from tackifier". Also, the peak height calculated in the peak (p _a) and "peak height of a peak derived from a tackifier."
When a plurality of corresponding peaks existed, the peak having the strongest Raman scattering intensity was selected from the corresponding peaks in the Raman spectrum (Ra).

(Iv) Calculation of peak height of peaks derived from components other than the tackifier In the Raman spectrum (Ra), other peaks that were not determined to be "peaks derived from the tackifier" in (iii) above were used. “Peak derived from a component other than the tackifier” was defined, and the peak height calculated at the peak was defined as “peak height of a peak derived from a component other than the tackifier”.
When there are a plurality of applicable peaks, in the Raman spectrum (Rb), among the corresponding peaks, the presence or absence of the tackifier has little effect on the Raman scattering intensity, and the Raman scattering intensity is stronger. I selected one.

(V) Calculation of strength ratio I of each layer "Peak height of peak derived from tackifier" and "Peak of peak derived from components other than tackifier" obtained through the above steps (i) to (iv) Based on the value of "height", the "strength ratio I" at each of the measurement positions in the cross section 121 of the pressure-sensitive adhesive layer was calculated from the above formula (1).
FIG. 5 is a graph showing the relationship between the measurement position (distance from the surface (β)) and the strength ratio I at the measurement position in the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet produced in Example 1.
In Example 1, a peak having a Raman shift of 1000 cm ^-1 is defined as a "peak derived from a tackifier", and a peak having a Raman shift of 1730 cm ^-1 is defined as a "peak derived from a component other than the tackifier". ".
Then, the average value of the intensity ratios I of all the measurement positions included in the layer (Xβ) was calculated as “the intensity ratio I of the layer (Xβ)”. Similarly, the average value of the intensity ratios I of all the measurement positions included in the layer (Y1) is defined as the "intensity ratio I of the layer (Y1)", and the intensity ratios I of all the measurement positions included in the layer (Xα) are The average value was calculated as "strength ratio I of layer (Xα)".
"Strength ratio I (Xβ) of layer (Xβ)", "Strength ratio I (Y1) of layer (Y1)", and "Layer (Xα)" in the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheets produced in Examples and Comparative Examples. ) Intensity ratio I (Xα) ”is shown in Table 4.
In addition, "the ratio of the intensity ratio I (Xβ) of the layer (Xβ) to the intensity ratio I (Xα) of the layer (Xα) [I (Xβ) / I (Xα)]" and "the intensity ratio of the layer (Xα)". The ratio of the intensity ratio I (Y1) of the layer (Y1) to I (Xα) [I (Y1) / I (Xα)] ”was also calculated, and these are also shown in Table 4.

<Observation of the surface (α) of the adhesive layer>
On the surface (α) of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet produced in Examples and Comparative Examples, four regions (D) surrounded by rectangles having a length of 8 mm and a width of 10 mm are arbitrarily selected, and within each region (D). Was observed and photographed with a digital microscope (manufactured by KEYENCE CORPORATION, product name "Digital Microscope VHX-1000", magnification: 50 times) in a plan view (stereoscopic view if necessary) from the surface (α) side.
Further, more specifically, in the shooting, the focus was moved in order from the upper part of the portion visually determined to be a flat surface from the direction A in FIG. 3, and the initially focused portion was photographed as a flat surface. ..
Further, using a digital microscope (magnification 50 times), a concatenated image in which arbitrarily selected ranges adjacent to each other on the surface (α) are concatenated by the image concatenation function of the digital microscope is acquired, and in the obtained concatenated image. , An area surrounded by a rectangle of 8 mm in length × 10 mm in width was arbitrarily selected, and this was designated as an “image of area (D)”.
If it is not possible to visually determine whether the surface is a flat surface, do not apply a load to the translucent adherend having a smooth surface on the surface (α) of the adhesive layer as much as possible. Hand-pasted with a squeegee, the interface between the smooth surface of the translucent adherend and the surface (α) 12a of the pressure-sensitive adhesive layer 12 was photographed from the direction A in FIG. 3, and the pasted portion is a flat surface. I decided. Non-alkali glass (product name "Eagle XG", manufactured by Corning Inc.) was used as the translucent adherend having a smooth surface.
The image of the obtained region (D) was observed, and the presence or absence of the recess, the shape of the recess, and the shape of the flat surface were observed. The results are shown in Table 4.

<Measurement of the area ratio occupied by the flat surface existing in the area (D)>
Based on the "image of the area (D)" acquired in the item of "observation of the state of the surface (α) of the adhesive layer" above, the area is automatically measured using the same digital microscope as above, and the area is measured. The area of each flat surface existing in (D) was obtained. The measurement results are shown in Table 4.
In the automatic area measurement, the flat surface existing in the area (D) is binarized by a digital microscope and, if necessary, visual image processing, and then the numerical value (area) of the binarized image obtained is obtained. The measurement was performed and the area of each flat surface was measured. When there were a plurality of flat surfaces, the area of each flat surface was measured. The "area ratio (%) occupied by the flat surface", which is the ratio of the total area of the obtained flat surfaces to the total area of the area (D), was calculated.
The conditions for automatic area measurement are as follows.
(Automatic area measurement conditions)
・ Extraction mode: Brightness (weak noise removal)
・ Extraction area: Extract a rectangle with a length of 8 mm and a width of 10 mm by specifying a numerical value (rectangle) ・ Shape of the extraction area: Grain removal (removal of area 100 μm ² or less)

<Mass retention of the adhesive layer of the adhesive sheet>
After obtaining only the pressure-sensitive adhesive layer from the pressure-sensitive adhesive sheet with a base material prepared in Examples and Comparative Examples, the mass of the pressure-sensitive adhesive layer before heating was measured. Then, the pressure-sensitive adhesive layer was put into a muffle furnace (manufactured by Denken Co., Ltd., product name "KDF-P90") and heated at 800 ° C. for 30 minutes.
Then, the mass of the pressure-sensitive adhesive layer after heating was measured, and the mass retention rate of the pressure-sensitive adhesive layer was calculated by the following formula. The calculated mass retention values are shown in Table 4.
Mass retention of pressure-sensitive adhesive layer (%) = [mass of pressure-sensitive adhesive layer after heating] / [mass of pressure-sensitive adhesive layer before heating] x 100

<Interlayer adhesion between the base material and the pressure-sensitive adhesive layer>
The adhesive sheet with a base material produced in Examples and Comparative Examples was allowed to stand in an environment of 23 ° C. and 50% RH (relative humidity) for 7 days, and a polycarbonate plate as an adherend (manufactured by Mitsubishi Gas Chemical Company, Inc., product) was allowed to stand. It was affixed to the name "Iupilon Sheet NF-2000VU"). After sticking, it was allowed to stand for 24 hours in an environment of 23 ° C. and 50% RH (relative humidity), and when the sticky adhesive sheet with a base material was slowly peeled off by hand, the base material and the pressure-sensitive adhesive layer were separated according to the following criteria. The interlayer adhesion was evaluated. The evaluation results are shown in Table 4.
A: Peeling is performed at the interface between the adherend and the pressure-sensitive adhesive layer, no peeling is observed between the base material and the pressure-sensitive adhesive layer, and the interlayer adhesion is excellent.
F: It is peeled off at the interface between the base material and the pressure-sensitive adhesive layer, and the interlayer adhesion is inferior.

<Adhesive strength>
The adhesive sheet with a base material produced in Examples and Comparative Examples was allowed to stand in an environment of 23 ° C. and 50% RH (relative humidity) for 7 days, cut into a size of 25 mm in length × 300 mm in width, and then the adhesive sheet was obtained. The surface (α) of the pressure-sensitive adhesive layer of No. 1 was affixed to a stainless steel plate (SUS304, No. 360 polishing) under the same environment to prepare a sample for measuring adhesive strength, and the sample was allowed to stand for 24 hours under the same environment.
After standing, the adhesive strength of each substrate-attached adhesive sheet was measured at a tensile speed of 300 mm / min by a 180 ° peeling method based on JIS Z0237: 2000. The measurement results of the adhesive strength are shown in Table 4.

<Air release>
The pressure-sensitive adhesive sheet with a base material produced in Examples and Comparative Examples had a size of 50 mm in length × 50 mm in width, and was then attached to a melamine-coated plate as an adherend so as to generate an air pool. Then, the presence or absence of an air pool after crimping with a squeegee was observed, and the air bleeding property of each adhesive sheet was evaluated according to the following criteria. The evaluation results are shown in Table 4.
A: The air pool has disappeared, and the air bleeding property is excellent.
F: An air pool remains, and the air bleeding property is inferior.

<Blister resistance>
The pressure-sensitive adhesive sheet with a base material produced in Examples and Comparative Examples had a size of 50 mm in length × 50 mm in width, and then a polymethylmethacrylate plate having a size of 70 mm in length × 150 mm in width × 2 mm in thickness (manufactured by Mitsubishi Rayon Co., Ltd., product name “ It was attached to Acrylite L001 ”) and strongly pressure-bonded with a squeegee to prepare a test sample.
This test sample was allowed to stand at 23 ° C. for 12 hours, then allowed to stand in a hot air dryer at 80 ° C. for 1.5 hours, and further allowed to stand in a hot air dryer at 90 ° C. for 1.5 hours to promote heating. The state of occurrence of blister was visually observed, and the blister resistance of each adhesive sheet was evaluated according to the following criteria. The evaluation results are shown in Table 4.
A: No blister was confirmed.
B: Blister was partially confirmed.
C: Blister was confirmed on the entire surface.

The pressure-sensitive adhesive sheets produced in Examples 1 to 3 had excellent interlayer adhesion between the base material and the pressure-sensitive adhesive layer, and also had good adhesive strength. On the other hand, the pressure-sensitive adhesive sheet produced in Comparative Example 1 resulted in inferior interlayer adhesion between the base material and the pressure-sensitive adhesive layer.

6 to 8 show a region surrounded by a rectangle of 8 mm in length × 10 mm in width arbitrarily selected on the exposed surface (α) of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheets prepared in Examples 1 to 3, respectively. D) is a binarized image of an image taken from the surface (α) side of the pressure-sensitive adhesive layer using a digital microscope. The black portion of the binarized image corresponds to a flat surface, and the white portion corresponds to a concave portion. The scale of each of the binarized images shown in FIGS. 6 to 8 is 8 mm in length and 10 mm in width.
As is clear from FIGS. 6 to 8, it was confirmed that the pressure-sensitive adhesive sheets prepared in Examples 1 to 3 had a plurality of amorphous recesses and flat surfaces on the surface (α) of the pressure-sensitive adhesive layer. Therefore, the air bleeding property of these adhesive sheets was good.
In addition, the pressure-sensitive adhesive sheets produced in Examples 1 to 3 also had good blister resistance.

The pressure-sensitive adhesive sheet according to one aspect of the present invention is useful as a pressure-sensitive adhesive sheet having a large sticking area, which is used for identification or decoration, for coating masking, for surface protection of metal plates and the like.

1, 1a, 1b Adhesive sheet 2 Easy-to-stick adhesive sheet 11 Base material 12 Adhesive layer 12a Surface (α)
12b surface (β)
121 Cross section 13 Recessed 14 Flat surface 15 Fine particles 50 Laser irradiation device 51 Excitation laser 52 Raman scattered light

Claims (13)

An adhesive sheet in which an adhesive layer containing an adhesive resin and an adhesive is directly laminated on a base material.
The pressure-sensitive adhesive layer includes a layer (Xα) containing a surface (α) having adhesiveness, a layer (Y1), and a layer (Xβ) containing a surface (β) directly laminated with the base material , in this order. It consists of a multi-layered structure that is laminated with
The layer (Xα) is formed from a composition (xα) which is a material for forming the layer (Xα).
The composition (xα) contains an acrylic resin having a functional group as the adhesive resin and a cross-linking agent.
An adhesive sheet in which the layer (Xα) and the layer (Xβ) satisfy the following requirements (I) and (II).
-Requirement (I): In the Raman spectrum of the layer (Xα) obtained by measurement by Raman spectroscopy, the intensity ratio I (Xα) of the layer (Xα) calculated from the following formula (1) is 0. It is 30 to 20.00.
-Requirement (II): In the Raman spectrum of the layer (Xβ) obtained by measurement by Raman spectroscopy, the intensity ratio I (Xβ) of the layer (Xβ) calculated from the following formula (1) is the layer. It is smaller than the intensity ratio I (Xα) of (Xα).
Formula (1): Strength ratio I = [Peak height of peak derived from the tackifier] / [Peak height of peak derived from components other than the tackifier] The pressure-sensitive adhesive sheet according to claim 1, wherein the strength ratio I (Xβ) of the layer (Xβ) is 0 to 15.0. Claim 1 in which the ratio of the intensity ratio I (Xβ) of the layer (Xβ) to the intensity ratio I (Xα) of the layer (Xα) [I (Xβ) / I (Xα)] is 0 to 0.90. Or the adhesive sheet according to 2. The pressure-sensitive adhesive sheet according to any one of claims 1 to 3, wherein the composition (xβ), which is a material for forming the layer (Xβ), contains the pressure-sensitive resin and substantially does not contain the pressure-sensitive adhesive. The composition (xα), which is the material for forming the layer (Xα), further contains the tackifier.
Any of claims 1 to 4, wherein the content of the tackifier in the composition (xα) is 1 part by mass or more with respect to 100 parts by mass of the adhesive resin contained in the composition (xα). The adhesive sheet described in item 1. The pressure-sensitive adhesive sheet according to any one of claims 1 to 5, wherein the acrylic resin having a functional group has a mass average molecular weight (Mw) of 250,000 to 1,500,000. In the Raman spectrum of the layer (Y1) obtained by measurement by Raman spectroscopy, the intensity ratio I (Y1) of the layer (Y1) calculated from the above formula (1) is 0 to 15.0. The adhesive sheet according to any one of claims 1 to 6. In the Raman spectrum of the layer (Y1) obtained by measurement by Raman spectroscopy, the intensity ratio of the layer (Y1) to the intensity ratio I (Xα) of the layer (Xα) calculated from the above formula (1). The adhesive sheet according to any one of claims 1 to 7, wherein the ratio of I (Y1) [I (Y1) / I (Xα)] is 0 to 0.90. The pressure-sensitive adhesive sheet according to any one of claims 1 to 8, wherein the layer (Y1) is a layer containing fine particles. The pressure-sensitive adhesive sheet according to claim 9, wherein the composition (y1), which is a material for forming the layer (Y1), contains 15 to 100% by mass of the fine particles. The pressure-sensitive adhesive sheet according to claim 9 or 10, which has an amorphous recess on the surface (α) of the layer (Xα). On the surface (α) of the layer (Xα), at least a coating film (xα') composed of a composition (xα) which is a material for forming the layer (Xα) and a composition (y1) which is a material for forming the layer (Y1). ) At the same time to dry the coating film (y1'), and there are recesses formed by self-formation that naturally create a disordered shape in the process of autonomous formation of the pressure-sensitive adhesive layer, claims 9 to 11. The adhesive sheet according to any one of the above. Any one of claims 1 to 12, wherein the tackifier includes one or more selected from a rosin-based tackifier, a terpene-based tackifier, a styrene-based tackifier, and a petroleum-derived tackifier. Adhesive sheet described in.

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