WO2014175306A1 - Adhesive sheet and laminate, and method for producing same - Google Patents

Abstract

　An adhesive composition comprises: a base polymer (A) containing a non-crosslinkable (meth)acrylic acid ester unit (a1) and an acrylic monomer unit (a2) having a crosslinkable functional group; a monomer (B) having at least one polymerizable unsaturated group; and a crosslinking agent (C) which reacts with the base polymer (A) in response to heat; a polymerization initiator (D) which initiates the polymerization reaction of the aforementioned monomer (B) in response to irradiation with an active energy beam; and a solvent (E). In addition to assuring tracking of recesses and protrusions, an adhesive sheet equipped with an adhesive layer (X) containing an adhesive semi-cured by heat can prevent deformation and/or distortion of a film, and can be produced at low cost.

Description

Adhesive sheet, laminate and method for producing the same

The present invention relates to a pressure-sensitive adhesive sheet and a laminate suitable for bonding a pair of concave and convex optical members, and a method for manufacturing the same.

In recent years, display devices such as a liquid crystal display (LCD) and input devices used in combination with a display device such as a touch panel have been widely used in various fields. In the manufacture of these display devices and input devices, transparent double-sided pressure-sensitive adhesive sheets are used for bonding optical members, and transparent double-sided pressure-sensitive adhesive sheets are also used for bonding between display devices and input devices. (For example, Patent Documents 1 to 3).
Some of the touch panels, liquid crystal displays, and the like include a constituent member having a step (unevenness) due to printing or the like. For example, a touch panel having a member provided with a frame-like print portion is used in a mobile phone. In such an application, the pressure-sensitive adhesive sheet is required to have a performance for filling a printing step at the same time as bonding and fixing a member, that is, an excellent unevenness followability (step absorption) (for example, Patent Document 4).

Patent Document 4 discloses an adhesive composition for bonding a liquid crystal panel and a cover panel, both of which are glass substrates, and a composition that absorbs a printing step. By the way, the structural member of a touch panel or a liquid crystal display includes a film type in addition to a plate-like substrate such as glass, and a double-sided pressure-sensitive adhesive sheet is also used for bonding a film and a glass substrate. The printing step may be provided on the film or may be provided on the plate-like substrate. For example, many decorative films having printing steps (unevenness) for imparting design properties and decorative properties are used. Decorative films have fewer processes and higher productivity than methods such as painting. On the other hand, decorative printing such as multi-layer ink printing and mirror printing has been applied due to the diversification of decoration in recent years. It is just a few tens of μm. When such a decorative film and a plate-like substrate are bonded together with a double-sided adhesive sheet with high unevenness followability, the adhesive layer is soft to follow the unevenness, and the decorative film cannot be held flat and decorated There was a problem that deformation and distortion occurred in the film. That is, there is a trade-off relationship between the unevenness followability and the deformation / distortion prevention of the decorative film, and it is difficult to achieve both.

In order to solve these problems, for example, there is a method in which the step portion is previously filled with a transparent resin and flattened, and then bonded with a double-sided pressure-sensitive adhesive sheet. However, the manufacturing process increases and the cost becomes high. Problems such as yellowing of the resin and an increase in haze value may occur.

Moreover, as a double-sided adhesive sheet used for such a use, the non-carrier type without a base material is common. Such a non-carrier double-sided pressure-sensitive adhesive sheet is generally produced by forming a pressure-sensitive adhesive layer on a heavy release separator and then laminating a light release separator.
For forming the pressure-sensitive adhesive layer, conventionally, an active energy ray-curable or thermosetting pressure-sensitive adhesive composition containing a base polymer has been used. As the base polymer, acrylic monomers such as alkyl (meth) acrylates, urethane (meth) acrylates, epoxy (meth) acrylates, polyester (meth) acrylates, polyether (meth) acrylates, etc. because of their excellent transparency An acrylic base polymer containing units is used.

As the active energy ray-curable pressure-sensitive adhesive composition, a solventless type is common. However, since a pressure-sensitive adhesive composition containing no solvent and having a high surface tension is applied to a release film having a low surface tension, production problems such as thick end portions (also referred to as framing and fat edges) are likely to occur.
As the thermosetting pressure-sensitive adhesive composition, one containing a solvent for diluting the base polymer is usually used. A thermosetting pressure-sensitive adhesive composition generally has an advantage of increasing cohesion by thermal crosslinking and improving holding power and heat resistance. However, there is a problem that coating defects such as aside (also called solvent popping) in the drying process are likely to occur. A coating defect is not preferable because it causes distortion in an image when used in a display or the like.
Such manufacturing problems such as thick edges and side walls are more likely to occur as the pressure-sensitive adhesive layer becomes thicker. For example, a thick-film pressure-sensitive adhesive layer having a thickness of 150 μm or more causes the above-described manufacturing problems. It is difficult to manufacture without.
Therefore, an acrylic pressure-sensitive adhesive composition that is excellent in coating suitability, can produce a pressure-sensitive adhesive layer with a smooth surface, and can be thickened, especially coating defects such as thick edges and side walls even if it contains a solvent. There is a need for an acrylic pressure-sensitive adhesive composition capable of forming a small pressure-sensitive adhesive layer.

In Patent Document 5, even if the pressure-sensitive adhesive layer is increased in order to enhance buffering properties, it can be easily re-peeled without damaging or contaminating the adherend, and it does not cause white turbidity even under high temperature and high humidity conditions. As the pressure-sensitive adhesive composition, an acrylic syrup obtained from a monomer represented by a specific structural formula, an alkyl acrylate and a carboxyl group-containing monomer and containing a polymer and a monomer has two or more polymerizable unsaturated groups. A photopolymerizable pressure-sensitive adhesive composition in which a monomer, a crosslinking agent, and a photopolymerization initiator are respectively blended in specific ratios, and a pressure-sensitive adhesive sheet having a thickness of 0.1 to 5 mm obtained by irradiating it with light are disclosed.
However, Patent Document 5 may contain a solvent such as an organic solvent, but in view of workability for producing a thick film sheet and influence on the environment, a solventless type that does not contain a solvent is preferable. There is no provision for a solvent that takes into account manufacturing problems such as coating defects. In addition, in the production example, a method (wet laminate) in which a liquid pressure-sensitive adhesive composition is sandwiched between release films and sealed in a sandwich form and then cured (wet laminate) is disclosed. Therefore, the addition of solvent is contraindicated.
In Patent Document 6, as a method for producing an ultraviolet curable pressure-sensitive adhesive layer having a thickness of 100 μm or more, a step of applying an ultraviolet curable pressure-sensitive adhesive composition on a substrate, a step of heating, and a step of irradiating ultraviolet rays are arranged in this order. A method of performing is disclosed. In this method, heating is performed before ultraviolet irradiation, whereby the thickness of the coating film is made uniform, and dents due to bubbles are improved.
However, this method is characterized by using a polymerizable monomer as a diluent and substantially not containing an organic solvent, and is not applicable to a pressure-sensitive adhesive containing a solvent. In addition, only urethane adhesives are actually evaluated.

By the way, as a double-sided pressure-sensitive adhesive sheet used for the above-described applications, a pressure-sensitive adhesive composition having both thermosetting and active energy ray-curing properties (hereinafter sometimes referred to as “dual curable pressure-sensitive adhesive composition”). It has been proposed to have a pressure-sensitive adhesive layer coated on a base material and thermally cured or active energy ray cured. Such an adhesive layer has active energy ray curability in the case of a thermoset, and thermosetting properties in the case of an active energy ray cure. Therefore, it can be temporarily bonded with adhesion at the time of bonding to the adherend, and then can be firmly bonded to the adherend by being cured by active energy rays or heating. It is said that both are compatible.
Conventionally, as a dual curable pressure-sensitive adhesive composition used for such a pressure-sensitive adhesive sheet, a crosslinking agent is added as a component for imparting thermosetting properties, and a monomer and a photoinitiator are blended in a base polymer as components for imparting active energy ray curing. What has been proposed.
For example, Patent Document 7 discloses a pressure-sensitive adhesive that combines two types of crosslinking methods, ultraviolet crosslinking and heat crosslinking, by blending a base polymer with both a UV-crosslinkable photocrosslinking agent and a heat-crosslinkable latent curing agent. A pressure-sensitive adhesive and a pressure-sensitive adhesive to be cross-linked by either one of the crosslinking methods and pasting the adherend and then post-crosslinked by the remaining crosslinking method are disclosed. The thing containing an agent is used.
Patent Document 8 discloses an active energy ray-curable pressure-sensitive adhesive composition containing a polymer having a maleimide group, and the composition further comprises an organic solvent, one or more ethylenic groups in the molecule. It describes that a compound having a saturated group, a photopolymerization initiator, a thermosetting crosslinking agent, and the like may be contained.

JP 2003-238915 A JP 2003-342542 A JP 2004-231723 A JP 2010-90204 A JP 2007-161908 A JP 2010-085578 A JP 2006-335840 A JP 2010-261029 A

However, in the pressure-sensitive adhesive sheet using the dual curable pressure-sensitive adhesive composition as described above, it has been clarified by the inventors that the unevenness followability cannot be sufficiently obtained. In addition, when a solvent is included, as with the above thermosetting pressure-sensitive adhesive composition, when coating and thermosetting, coating defects such as thick edges and side walls are likely to occur, and the film may be deformed or distorted. was there.
Therefore, an object of the present invention is to provide a pressure-sensitive adhesive sheet, a method of using the same, and a laminate that can easily ensure unevenness followability, can prevent deformation and distortion of a film, and are low in cost.

That is, this invention has the following aspects.
[1] A base polymer (A) containing a non-crosslinkable (meth) acrylic acid ester unit (a1) and an acrylic monomer unit (a2) having a crosslinkable functional group, and at least one polymerizable unsaturated group A monomer (B) having, a crosslinking agent (C) that reacts with the base polymer (A) by heat, and a polymerization initiator that initiates a polymerization reaction of the monomer (B) by irradiation with active energy rays ( An adhesive sheet provided with the adhesive layer (X) containing the adhesive which semi-hardened the adhesive composition containing D) and a solvent (E) by heating.
[2] The pressure-sensitive adhesive sheet according to [1], wherein the monomer (B) has an alkyl group having a chain length atom number of 10 or more.
[3] The pressure-sensitive adhesive sheet according to [2], wherein the alkyl group has a chain length atom number of 15 to 22.
[4] A base polymer (A) containing a non-crosslinkable (meth) acrylic acid ester unit (a1) and an acrylic monomer unit (a2) having a crosslinkable functional group, and at least one polymerizable unsaturated group A monomer (B) having an alkyl group having a chain length of 15 to 22, a crosslinking agent (C) which reacts with the base polymer (A) by heat, and the monomer by irradiation with active energy rays An adhesive sheet provided with the adhesive layer (X) containing the adhesive which heated the polymerization initiator (D) which starts the polymerization reaction of (B), and the solvent (E), and heated the adhesive composition.
[5] The pressure-sensitive adhesive sheet according to any one of [1] to [4], wherein the monomer (B) is isostearyl acrylate.
[6] The monomer (B) has a vapor pressure at 25 ° C. of 300 Pa or less,
The pressure-sensitive adhesive sheet according to any one of [1] to [5], wherein the solvent (E) has a surface tension at 25 ° C. of 20 mN / m or more and less than 40 mN / m.
[7] A monofunctional monomer (B1) having one polymerizable unsaturated group having a melting point of 25 ° C. or lower and a polyfunctional monofunctional monomer having two or more polymerizable unsaturated groups. The pressure-sensitive adhesive sheet according to any one of [1] to [6], which contains at least one of the monomer (B2).
[8] The pressure-sensitive adhesive sheet according to any one of [1] to [7], wherein the monomer (B) has a polycyclic structure.
[9] The pressure-sensitive adhesive sheet according to [8], wherein the monomer (B) is an acrylate having a bicyclo ring or a tricyclo ring.
[10] The solvent (E) according to any one of [1] to [9], wherein the solvent (E) does not have a polymerizable unsaturated group and has a higher vapor pressure at 25 ° C. than the monomer (B). Adhesive sheet.
[11] The solvent (E) is composed of a solvent having a solubility parameter difference within 2 [(cal / cm ³ ) ^1/2 ] from the monomer (B) [1] to [10 ] The adhesive sheet of any one of.
[12] The holding force measured according to JIS Z0237 after being cured by pressure bonding to a SUS plate and irradiating with active energy rays is 360 minutes or more, according to any one of [1] to [11] Adhesive sheet.
[13] The pressure-sensitive adhesive sheet according to any one of [1] to [12], which is a double-sided pressure-sensitive adhesive sheet.
[14] The pressure-sensitive adhesive layer (X) of the pressure-sensitive adhesive sheet according to any one of [1] to [13] is brought into contact with the surface of the adherend and irradiated with active energy rays in this state. The manufacturing method of a laminated body including complete-curing (X).
[15] A pair of optical members is bonded via the pressure-sensitive adhesive sheet according to any one of [1] to [13], and active energy rays are irradiated in this state to completely form the pressure-sensitive adhesive layer (X). A laminate obtained by curing.

The pressure-sensitive adhesive sheet of the present invention is easy to ensure uneven followability with respect to a printing step (unevenness) when bonding a pair of optical members, and can prevent deformation and distortion of the film, and is low in cost. The use method and a laminated body are provided.

It is an adhesive sheet of the present invention. It is sectional drawing which shows a part of touch panel module which is embodiment of this invention.

Hereinafter, the present invention will be described in detail. The description of the constituent elements described below may be made based on representative embodiments and specific examples, but the present invention is not limited to such embodiments. In the present specification, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

Embodiment of the adhesive sheet of this invention is described.
The pressure-sensitive adhesive sheet of the present invention comprises a base polymer (A) containing a non-crosslinkable (meth) acrylic acid ester unit (a1) and an acrylic monomer unit (a2) having a crosslinkable functional group, and a polymerizable unsaturated group. A monomer (B) having at least one of the above, a crosslinking agent (C) that reacts with the base polymer (A) by heat, and the polymerization reaction of the monomer (B) is initiated by irradiation with active energy rays. An adhesive layer (X) containing an adhesive obtained by semi-curing an adhesive composition containing a polymerization initiator (D) and a solvent (E) by heating is provided.

FIG. 1 is an adhesive sheet (with a release sheet) of the present invention.
FIG. 2 is a part of the configuration of the touch panel module in which an optical member is bonded with the pressure-sensitive adhesive sheet of the present invention. The pressure-sensitive adhesive sheet 1 of the present embodiment functions as a double-sided pressure-sensitive adhesive sheet. The pressure-sensitive adhesive sheet 1 is used when the decorative film 22 and the ITO glass substrate 24 are bonded to each other, and a printing step (23a, 23b) is provided on the adhesive surface 22a of the decorative film 22 with the pressure-sensitive adhesive layer. It has been.
Or the printing level | step difference (23c, 23d) may be provided in the adhesive surface 24a with the adhesive layer of the ITO glass substrate 24. FIG. The thickness of the printing step 23 is usually 5 to 60 μm.

(Adhesive layer)
The pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1 of the present invention includes a base polymer (A) containing a non-crosslinkable (meth) acrylic acid ester unit (a1) and an acrylic monomer unit (a2) having a crosslinkable functional group, A monomer (B) having at least one polymerizable unsaturated group, a crosslinking agent (C) that reacts with the base polymer (A) by heat, and irradiation of active energy rays to form the monomer (B). A pressure-sensitive adhesive layer containing a pressure-sensitive adhesive composition obtained by heating a pressure-sensitive adhesive composition containing a polymerization initiator (D) and a solvent (E) to initiate a polymerization reaction, and exhibiting a soft semi-cured state Yes. Semi-cured in the present invention means that the gel fraction is less than 20%, and the gel fraction is preferably less than 15%, more preferably less than 10%. And an adhesive layer is completely hardened | cured by irradiating an active energy ray after bonding the decorating film 22 and the ITO glass substrate 24. FIG.
That is, the pressure-sensitive adhesive sheet 1 of the present invention has a pressure-sensitive adhesive layer 11 that is semi-cured only by heat before bonding, and the pressure-sensitive adhesive layer 11 is completely cured by active energy rays after bonding. It is a sheet.
Hereinafter, “semi-cured” in the present specification means that the pressure-sensitive adhesive layer is first cured only by heat, and “semi-cured state” is after heat curing and before irradiation with active energy rays. The pressure-sensitive adhesive layer refers to a state in which the dynamic viscoelasticity becomes 1.5 times or more after curing. The dynamic viscoelasticity is preferably 1.5 to 1000 times, more preferably 2 to 100 times. In the semi-cured state in the present invention, the dynamic viscoelasticity of the pressure-sensitive adhesive layer is preferably 1.0 × 10 ⁶ Pa or less, more preferably 8.0 × 10 ⁵ Pa or less, and 5.0 × 10 ^5. Pa or less is particularly preferable. “Fully cured” refers to curing the pressure-sensitive adhesive layer with active energy rays after being semi-cured by heat.

As the base polymer for forming the pressure-sensitive adhesive layer 11, a base polymer having transparency that does not deteriorate the visibility of the display device is preferable. The base polymer contains a non-crosslinkable (meth) acrylic acid ester unit (a1) and an acrylic monomer unit (a2) having a crosslinkable functional group.

The pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer 11 includes a base polymer (A) containing a non-crosslinkable (meth) acrylic acid ester unit (a1) and an acrylic monomer unit (a2) having a crosslinkable functional group; A monomer (B) having at least one polymerizable unsaturated group, a crosslinking agent (C) that reacts with the base polymer (A) by heat, and the monomer (B) by irradiation with active energy rays A polymerization initiator (D) for initiating the polymerization reaction and a solvent (E).

<Adhesive composition>
The pressure-sensitive adhesive composition comprises a non-crosslinkable (meth) acrylic acid ester unit (a1) and a base polymer (A2) containing an acrylic monomer unit (a2) having a crosslinkable functional group, and a polymerizable unsaturated group A monomer (B) having at least one of the above, a crosslinking agent (C) that reacts with the base polymer (A) by heat, and the polymerization reaction of the monomer (B) is initiated by irradiation with active energy rays. A polymerization initiator (D) and a solvent (E) are contained.

The pressure-sensitive adhesive composition contains the monomer (B) whose vapor pressure at 25 ° C. is 300 Pa or less, and the surface tension at 25 ° C. of the solvent (E) is 20 mN / m or more and less than 40 mN / m. can do. Thereby, the coating suitability is improved, and a pressure-sensitive adhesive layer having a smooth surface can be formed when coating and thermosetting.
This is considered to be due to the following reason. First, by containing the solvent (E), the problem of the thick end portion is less likely to occur during coating. Moreover, the density | concentration of the solvent (E) which tends to cause a side can be restrained low by containing the monomer (B) which functions as a liquid medium which makes a coating material low viscosity like a solvent (E). In addition, the solvent (E) selectively evaporates when heated, but by containing the monomer (B) that is difficult to volatilize, a rapid increase in the surface tension of the coating film is suppressed, and further the solvent (E ), The viscosity increases as the concentration of the pressure-sensitive adhesive layer increases, and the flow of the substance in the pressure-sensitive adhesive layer is suppressed. By acting synergistically, it is considered that production problems such as thick-walled edges and armpits are suppressed, and an adhesive layer having a smooth surface can be formed.
The above effect is particularly excellent when at least one, preferably all of the following conditions (1) and (2) are satisfied.
(1) Melting | fusing point of a monomer (B) is 25 degrees C or less.
(2) The solvent (E) does not have a polymerizable unsaturated group and has a higher vapor pressure at 25 ° C. than the monomer (B).
The vapor pressure and melting point of such a monomer, the vapor pressure and surface tension of the solvent are not particularly considered in the above-mentioned Patent Documents 7 to 8.

In the pressure-sensitive adhesive composition, the solvent (E) has a difference in solubility parameter between the solvent (E) and the monomer (B) within 2 [(cal / cm ³ ) ^1/2 ]. It is preferable. Thereby, the coating suitability is improved, and a pressure-sensitive adhesive layer having a smooth surface can be formed when coating and thermosetting.
This is considered to be due to the following reason. First, by containing the solvent (E), the problem of coating defects such as thick-walled end portions is less likely to occur during coating. In addition, when the solvent (E) is composed of a solvent having a solubility parameter within 2 [(cal / cm ³ ) ^1/2 ] with respect to the monomer (B), Since the rapid evaporation of the solvent (E) due to excessive collapse of the gas-liquid equilibrium is suppressed, the problem of coating defects called yuzu skin (orange peel) is less likely to occur. Moreover, the density | concentration of the solvent (E) which tends to cause a coating defect is restrained low by containing the monomer (B) which functions as a liquid medium which makes a coating material low viscosity like a solvent (E). . Moreover, when heated, the viscosity increases as the concentration of the pressure-sensitive adhesive layer increases due to evaporation of the solvent (E), and the flow of the substance in the pressure-sensitive adhesive layer is suppressed. By synergistically acting, it is considered that manufacturing problems such as thick-walled edges and coating defects are suppressed, and an adhesive layer having a smooth surface can be formed.
When the solvent (E) contains a solvent having a solubility parameter difference of more than 2 [(cal / cm ³ ) ^1/2 ] with respect to the monomer (B), the solvent ( E) evaporates rapidly, coating defects such as yuzu skin (orange peel) are likely to occur, and a pressure-sensitive adhesive layer having a smooth surface tends to be hardly obtained.

The above effect is particularly excellent when the solvent (E) does not have a polymerizable unsaturated group and the surface tension at 25 ° C. is 20 mN / m or more and less than 40 mN / m. That is, in the pressure-sensitive adhesive composition, the monomer (B) has a vapor pressure at 25 ° C. of 300 Pa or less, and the surface tension at 25 ° C. of the solvent (E) is 20 mN / m or more and less than 40 mN / m, Furthermore, the solvent (E) is preferably composed of a solvent having a difference in solubility parameter from the monomer (B) within 2 [(cal / cm ³ ) ^1/2 ]. The difference in solubility parameter between the solvent and the monomer and the surface tension of the solvent are not particularly taken into consideration in the above-mentioned Patent Documents 7 to 8.

[Base polymer (A)]
The pressure-sensitive adhesive layer contains a non-crosslinkable (meth) acrylic acid ester unit (a1) and an acrylic monomer unit (a2) having a crosslinkable functional group as the base polymer (A).
In the present specification and claims, the “unit” is a repeating unit (monomer unit) constituting the polymer.

The non-crosslinkable (meth) acrylic acid ester unit (a1) is derived from a (meth) acrylic acid alkyl ester.
Examples of (meth) acrylic acid alkyl esters include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, (meth) Isobutyl acrylate, t-butyl (meth) acrylate, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, ( Isooctyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, n-undecyl (meth) acrylate, (meth) N-dodecyl acrylate, stearyl (meth) acrylate, methoxyethyl (meth) acrylate, (meth ) Ethoxyethyl acrylate, cyclohexyl (meth) acrylate include benzyl (meth) acrylate and the like. These may be used individually by 1 type and may use 2 or more types together.
Among the above (meth) acrylic acid alkyl esters, since the tackiness is increased, at least one selected from methyl (meth) acrylate, n-butyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate is provided. preferable.
In the present invention, “(meth) acrylate” means containing both “acrylate” and “methacrylate”, and “(meth) acrylic acid” means “acrylic acid” and “methacrylic acid”. Is meant to include both.

Examples of the acrylic monomer unit (a2) having a crosslinkable functional group include a hydroxy group-containing monomer unit, an amino group-containing monomer unit, a glycidyl group-containing monomer unit, and a carboxy group-containing monomer unit. It is done. Among these, a hydroxy group-containing monomer unit and an amino group-containing monomer unit are preferable, and a hydroxy group-containing monomer unit is particularly preferable.
These monomer units may be one type or two or more types. However, the ratio of the carboxy group-containing monomer unit contained in the acrylic monomer unit (a2) is preferably 1% or less with respect to the total mass of the acrylic monomer unit (a2). It is more preferably 1% or less, and particularly preferably 0%. By making the ratio of the carboxy group-containing monomer unit contained in the acrylic monomer unit (a2) within the above range, the corrosiveness to the metal wiring provided on the surface of the adherend can be suppressed.

The hydroxy group-containing monomer unit is derived from a hydroxy group-containing monomer. Examples of the hydroxy group-containing monomer include hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, (Meth) acrylic acid lactones such as (meth) acrylic acid mono (diethylene glycol) (meth) acrylic acid [(mono, di or poly) alkylene glycol] and (meth) acrylic acid monocaprolactone.
Examples of the amino group-containing monomer unit include those derived from amino group-containing monomers such as (meth) acrylamide and allylamine.
Examples of the glycidyl group-containing monomer unit include those derived from glycidyl group-containing monomers such as glycidyl (meth) acrylate.
Examples of the carboxy group-containing monomer unit include acrylic acid and methacrylic acid.
The content of the crosslinkable acrylic monomer unit (a2) in the base polymer (A) is preferably 0.01 to 20% by mass, more preferably 0.5 to 15% by mass, and 0.5 to 10% by mass. % Is more preferable. If the content of the crosslinkable acrylic monomer unit (a2) is not less than the lower limit of the above range, it has sufficient crosslinkability to maintain a semi-cured state and is not more than the upper limit of the above range. If so, the necessary adhesive properties can be maintained.

The base polymer (A) has a monomer unit other than the non-crosslinkable (meth) acrylic acid ester unit (a1) and the acrylic monomer unit (a2) having a crosslinkable functional group, if necessary. May be. The other monomer is not particularly limited as long as it is copolymerizable with a non-crosslinkable (meth) acrylic acid ester and an acrylic monomer having a crosslinkable functional group. For example, (meth) acrylonitrile, vinyl acetate, styrene , Vinyl chloride, vinyl pyrrolidone, vinyl pyridine and the like.
The content of the arbitrary monomer unit in the base polymer (A) is preferably 0 to 20% by mass, and more preferably 0 to 15% by mass.

The weight average molecular weight of the base polymer (A) is preferably 100,000 to 2,000,000, more preferably 300,000 to 1,500,000. If the weight average molecular weight is equal to or higher than the lower limit, a semi-cured state can be maintained, and sufficient unevenness followability can be ensured if the upper limit is not exceeded. In addition, the weight average molecular weight of a base polymer (A) is a value before bridge | crosslinking with a crosslinking agent. The weight average molecular weight is a value determined by size exclusion chromatography (SEC) and determined on a polystyrene basis. As the base polymer (A), a commercially available product may be used, or a polymer synthesized by a known method may be used.

[Monomer (B)]
The monomer (B) contains at least one of a monofunctional monomer (B1) having at least one polymerizable unsaturated group and a polyfunctional monomer (B2) having two or more polymerizable unsaturated groups. It is preferable to do. The monomer (B) preferably contains either the monofunctional monomer (B1) or the polyfunctional monomer (B2). The monofunctional monomer (B1) and the polyfunctional monomer (B B2) may be included.
By containing the monomer (B), when the pressure-sensitive adhesive composition is thermally cured, the pressure-sensitive adhesive layer of the thermoset is in a semi-cured state and can have active energy ray curability.
The polymerizable unsaturated group is preferably a group containing an ethylenic double bond, and examples thereof include a (meth) acryloyl group and a vinyl group. Of these, a (meth) acryloyl group is particularly preferable.

As the monomer (B), one having a vapor pressure at 25 ° C. of 300 Pa or less is preferable. Thereby, the coating suitability is improved, and when the coating and thermosetting are performed, a pressure-sensitive adhesive layer having few coating defects such as thick end portions and side walls can be formed while selectively evaporating the solvent.
The vapor pressure at 25 ° C. of the monomer (B) is more preferably 200 Pa or less, and further preferably 100 Pa or less. The lower limit of the vapor pressure is not particularly limited in terms of coating suitability. The vapor pressure of the monomer (B) can be measured according to JIS-K2258 “Crude oil and fuel oil—Vapor pressure test method—Reed method” and the like, for example, http: // www. chemspider. The predicted value can be obtained by a website such as com / or software such as ACD / PhysChem Suite.
The monomer (B) preferably further has a melting point of 25 ° C. or lower. Thereby, transparency (haze etc.) etc. of the adhesive layer formed improve. Further, the melting point of the monomer (B) is more preferably 20 ° C. or less, and further preferably 15 ° C. or less. The lower limit of the melting point is not particularly limited. The melting point of the monomer (B) can be measured according to JIS K 0064: 1992 “Measuring method of melting point and melting range of chemical product”.

If a monomer having an alkyl group having a chain length of 10 or more or a monomer having a polycyclic structure is used as the monomer (B), it is possible to exhibit a further excellent holding power after curing. it can.
Usually, in order to polymerize a monomer as a higher molecular weight, the shorter the number of chain-length atoms, the better the monomers can be bonded to each other, and the more excellent curing occurs. However, in the present invention, it is considered that by using the monomer as described above, the monomer and the base polymer are entangled with each other so that the monomer is easily cured and excellent holding power can be exhibited.
Examples of the monomer having an alkyl group having 10 or more chain length atoms include alkyl acrylates having an alkyl group having 10 or more chain length atoms. As long as the alkyl group has 10 or more chain-length atoms, it may have a side chain or a substituent. Examples of such a side chain or substituent include an alkyl group. The chain length atom number of the alkyl group is preferably 10 to 27, more preferably 10 to 25, and still more preferably 15 to 22. Isostearyl acrylate can be mentioned as a particularly preferred alkyl acrylate from the viewpoint of holding power.
The monomer having a polycyclic structure may be a polycyclic aliphatic monomer or a polycyclic aromatic monomer, and is preferably a polycyclic aliphatic monomer. Among the polycyclic structures, a bicyclo structure and a tricyclo structure are preferable. A substituent such as an alkyl group may be bonded to these polycyclic structures. Specific examples of the polycyclic structure include a norbornene ring and an adamantane ring.

Specific examples of the monofunctional monomer (B1) that can be used in the present invention include pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, and n-octyl (meth) acrylate. , Iso-octyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, n-undecyl (meth) acrylate, ( Preference is given to at least one selected from lauryl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, isobornyl (meth) acrylate, 2-ethylhexyl (meth) acrylate and the like.
Among these, the melting point is 25 ° C. or less, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, ( N-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, n-undecyl (meth) acrylate, lauryl (meth) acrylate, (meth) Particularly preferred is at least one selected from isostearyl acrylate, isobornyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate.

Examples of the polyfunctional monomer (B2) include ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, and di (meth) acryl. 1,4-butylene glycol acid, 1,9-nonanediol di (meth) acrylate, 1,6-hexanediol diacrylate, polybutylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, Tetraethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, tetra ( Many such as (meth) acrylic acid pentaerythritol (Meth) acrylic acid esters of alcohols, and vinyl methacrylate.
In addition, it is preferable that a monomer (B) is a thing which does not have a functional group which reacts with the functional group which an acrylic monomer unit (a2) has. For example, the monomer (B) preferably has the same functional group (for example, hydroxy group) as the acrylic monomer unit (a2) or has no functional group.

The monomer (B) is a monofunctional monomer (B1) or a polyfunctional monomer (B2) alone, or a monofunctional monomer (B1) and / or a polyfunctional monomer ( Two or more types of B2) may be used in combination.
In the pressure-sensitive adhesive composition, the content of the monomer (B) is appropriately selected according to the composition, molecular weight, crosslinking density and the like of the base polymer (A), and is not particularly limited, but is 100 mass of the base polymer (A). 5 to 150 parts by mass is preferable, 10 to 120 parts by mass is more preferable, and 15 to 90 parts by mass is still more preferable. If the content of the monomer (B) is not less than the lower limit value of the above range, the irregularity followability of the deformation / distortion prevention performance is excellent, and if it is not more than the upper limit value of the above range, the workability is excellent.
Further, the content of the monomer (B) is preferably 1 to 60% by mass, more preferably 2 to 50% by mass, and more preferably 5 to 35% by mass with respect to the total mass of the pressure-sensitive adhesive composition. % Is more preferable.
In particular, when the monomer (B) contains both the monofunctional monomer (B1) and the polyfunctional monomer (B2), it is appropriately selected according to the composition, molecular weight, crosslinking density, etc. of the polymer (A). The monofunctional monomer (B1) is preferably 4 to 120 parts by weight, more preferably 8 to 100 parts by weight, and more preferably 12 to 80 parts by weight with respect to 100 parts by weight of the base polymer (A). More preferably, the polyfunctional monomer (B2) is preferably 1 to 30 parts by mass, more preferably 2 to 20 parts by mass, and even more preferably 3 to 10 parts by mass. The mass ratio of the monofunctional monomer (B1) and the polyfunctional monomer (B2) is 2: 1, preferably 3: 1, and more preferably 5: 1.

[Crosslinking agent (C)]
The crosslinking agent (C) is not particularly limited. For example, the base polymer (A) is selected from known crosslinking agents such as isocyanate compounds, epoxy compounds, oxazoline compounds, aziridine compounds, metal chelate compounds, butylated melamine compounds. It can select suitably in consideration of the reactivity with the crosslinkable functional group which has. For example, when a hydroxy group is included as a crosslinkable functional group, it is preferable to use an isocyanate compound from the reactivity of the hydroxy group.
Among these, an isocyanate compound and an epoxy compound are preferable because the acrylic monomer unit (a2) having a crosslinkable functional group can be easily crosslinked.

Examples of the isocyanate compound include tolylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate.
Examples of the epoxy compound include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, glycerin diglycidyl ether, neopentyl glycol diglycidyl ether, and 1,6-hexanediol diester. Glycidyl ether, tetraglycidyl xylenediamine, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, trimethylolpropane polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitol polyglycidyl ether, etc. Can be mentioned.

As a crosslinking agent (C), 1 type may be used independently or 2 or more types may be used together.
In the pressure-sensitive adhesive composition, the content of the crosslinking agent (C) is appropriately selected according to the desired physical properties of the pressure-sensitive adhesive, and is not particularly limited, but is 0.01 to 5 with respect to 100 parts by mass of the base polymer (A). Part by mass is preferable, and 0.03 to 3 parts by mass is more preferable. If the content of the crosslinking agent (C) is not less than the lower limit value, the processability and the substrate adhesion are excellent, and if it is not more than the upper limit value, the unevenness followability and the film deformation / distortion prevention performance are excellent.
In addition, the content of the crosslinking agent (C) is preferably 0.01 to 5.0% by mass and preferably 0.02 to 2.0% by mass with respect to the total mass of the pressure-sensitive adhesive composition. More preferred.

[Polymerization initiator (D)]
As the polymerization initiator (D), any polymerization initiator may be used as long as it can initiate the polymerization reaction of the monomer (B) by irradiation with active energy rays.
Here, “active energy rays” mean those having energy quanta among electromagnetic waves or charged particle beams, and examples include ultraviolet rays, electron beams, visible rays, X-rays, ion rays and the like. Among these, from the viewpoint of versatility, ultraviolet rays or electron beams are preferable, and ultraviolet rays are particularly preferable.

Examples of the polymerization initiator (D) include acetophenone-based initiators, benzoin ether-based initiators, benzophenone-based initiators, hydroxyalkylphenone-based initiators, thioxanthone-based initiators, and amine-based initiators. Of these, specific examples of the acetophenone-based initiator include diethoxyacetophenone and benzyldimethyl ketal. Specific examples of the benzoin ether initiator include benzoin and benzoin methyl ether. Specific examples of the benzophenone initiator include benzophenone and methyl o-benzoylbenzoate. Specific examples of the hydroxyalkylphenone initiator include 1-hydroxy-cyclohexyl-phenyl-ketone and the like. Specific examples of the thioxanthone initiator include 2-isopropylthioxanthone and 2,4-dimethylthioxanthone. Specific examples of the amine initiator include triethanolamine, ethyl 4-dimethylbenzoate and the like.

As the polymerization initiator (D), one type may be used alone, or two or more types may be used in combination.
In the pressure-sensitive adhesive composition, the content of the polymerization initiator (D) is appropriately selected according to the content of the monomer (B), the irradiation amount of active energy rays when completely cured, etc., and is not particularly limited. The total mass of the monomer (B) is preferably 0.05 to 10% by mass, more preferably 0.1 to 5.0% by mass. If it is more than the said lower limit, the polymerization reaction at the time of complete curing can be easily started, and if it is less than the said upper limit, the substrate is hardly damaged due to the influence of the heat of polymerization reaction at the time of complete curing.
The content of the polymerization initiator (D) is preferably 0.1 to 10 parts by mass, more preferably 1 to 5 parts by mass with respect to 100 parts by mass of the base polymer (A).

[Solvent (E)]
The solvent (E) is used for improving the coating suitability of the pressure-sensitive adhesive composition.

Examples of such a solvent (E) include hydrocarbons such as hexane, heptane, octane, toluene, xylene, ethylbenzene, cyclohexane, and methylcyclohexane; halogenated hydrocarbons such as dichloromethane, trichloroethane, trichloroethylene, tetrachloroethylene, and dichloropropane. Alcohols such as methanol, ethanol, propanol, isopropyl alcohol, butanol, isobutyl alcohol and diacetone alcohol; ethers such as diethyl ether, diisopropyl ether, dioxane and tetrahydrofuran; acetone, methyl ethyl ketone, methyl isobutyl ketone, isophorone and cyclohexanone Ketones; methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, amyl acetate, ethyl butyrate Esters and the like; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, polyols and derivatives thereof such as propylene glycol monomethyl ether acetate.

As the solvent (E), a solvent having no polymerizable unsaturated group and having a higher vapor pressure at 25 ° C. than that of the monomer (B) is particularly preferable.
The greater the difference between the vapor pressures of the monomer (B) and the solvent (E), the fewer the coating defects and the easier the production. Therefore, the vapor pressure of the solvent (E) is preferably 2000 Pa or more and particularly preferably 5000 Pa or more. . Although an upper limit is not specifically limited, 50000 Pa or less is preferable practically.
The vapor pressure of the solvent (E) can be measured according to JIS-K2258-2 “Crude oil and petroleum products—Determination of vapor pressure—Part 2: Three-time expansion method”, for example, http: // www. chemspider. com / and software such as ACD / PhysChem Suite.

The solvent having no polymerizable unsaturated group and having a higher vapor pressure at 25 ° C. than that of the monomer (B) varies depending on the monomer (B), but hexane, heptane, cyclohexane, benzene, toluene, Examples include ethanol, isopropyl alcohol, diisopropyl ether, tetrahydrofuran, acetone, methyl ethyl ketone, methyl isobutyl ketone, and ethyl acetate.

Further, the solvent (E) has a surface tension at 25 ° C. of preferably 20 mN / m or more and less than 40 mN / m, and more preferably 22 mN / m or more and less than 36 N / m. If the surface tension is greater than or equal to the lower limit of the range, application defects such as yuzu skin (orange peel) are unlikely to occur, and if the surface tension is less than the upper limit of the range, application defects such as thick edges (framing) are less likely to occur.

The solvent (E) has a difference in solubility parameter from the monomer (B) within 2 [(cal / cm ³ ) ^1/2 ], preferably 1.5 [(cal / cm ³ ) ^1/2 ]. The following solvents can be used. As a result, coating defects such as yuzu skin (orange peel) due to abnormally accelerated evaporation of the solvent (E) are unlikely to occur.
The solubility parameter serves as a guide for dissolution and has the meaning of the following formula.
δ = (ΔE / V) ^1/2
Here, δ is a solubility parameter, ΔE is molar evaporation energy (cal / mol), and V is molar volume (cm ³ / mol). Those having a similar solubility parameter δ dissolve well. It agrees with the rule of thumb that similar things melt well. The solubility parameter can be determined by various methods, but a method of calculating from the chemical composition by the Fedors method is simple.

A solvent (E) may be used individually by 1 type, and may use 2 or more types together.
The content of the solvent (E) in the pressure-sensitive adhesive composition is not particularly limited, but is preferably 25 to 500 parts by mass, more preferably 30 to 400 parts by mass with respect to 100 parts by mass of the base polymer (A). If the content of the solvent (E) is not less than the lower limit of the above range, coating defects such as thick edges are unlikely to occur and the coating suitability is excellent. Coating defects such as (solvent popping) are less likely to occur, and coating suitability is excellent.
The content of the solvent (E) is preferably 10 to 90% by mass and more preferably 20 to 80% by mass with respect to the total mass of the pressure-sensitive adhesive composition.

[Plasticizer]
The pressure-sensitive adhesive sheet 1 of the present invention may contain a plasticizer in the pressure-sensitive adhesive composition for the purpose of further improving the unevenness followability. When a plasticizer is contained, the plasticizer is preferably contained in an amount of 50 parts by mass or less, and 30 parts by mass or less with respect to 100 parts by mass of the base polymer (A) contained in each pressure-sensitive adhesive composition. More preferably, it is more preferably 10 parts by mass or less.

As the plasticizer, a non-functional acrylic polymer is particularly preferable. A non-functional acrylic polymer is a polymer consisting only of an acrylic monomer unit having no functional group other than an acrylate group, or an acrylic monomer unit having no functional group other than an acrylate group and no functional group. It means a polymer composed of non-acrylic monomer units. Since the non-functional acrylic polymer is not cross-linked with the base polymer (A), it is possible to improve the unevenness followability without affecting the adhesive physical properties.
As an acryl monomer unit which does not have functional groups other than an acrylate group, the thing similar to the said non-crosslinkable (meth) acrylic acid ester unit (a1) is mentioned, for example.
Non-acrylic monomer units having no functional group include, for example, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caproate, vinyl caprylate, vinyl caprate, vinyl laurate, vinyl myristate, vinyl palmitate, stearin. Examples thereof include carboxylic acid vinyl esters such as vinyl acid vinyl, vinyl cyclohexanecarboxylate, and vinyl benzoate, and styrene.

[Optional ingredients]
The pressure-sensitive adhesive composition may optionally contain other components other than those described above as long as the effects of the present invention are not impaired. Examples of the other components include those known as additives for pressure-sensitive adhesives, such as antioxidants, metal corrosion inhibitors, tackifiers, silane coupling agents, ultraviolet absorbers, light stabilizers such as hindered amine compounds, and the like. You can select from among them.
Examples of the antioxidant include phenolic antioxidants, amine-based antioxidants, lactone-based antioxidants, phosphorus-based antioxidants, sulfur-based antioxidants, and the like. These antioxidants may be used alone or in combination of two or more.
As the metal corrosion inhibitor, a benzoriazol-based resin is preferable because of the compatibility and high effect of the pressure-sensitive adhesive.
Examples of the tackifier include rosin resin, terpene resin, terpene phenol resin, coumarone indene resin, styrene resin, xylene resin, phenol resin, and petroleum resin.
Examples of the silane coupling agent include mercaptoalkoxysilane compounds (for example, mercapto group-substituted alkoxy oligomers).
Examples of the ultraviolet absorber include benzotriazole compounds and benzophenone compounds. However, when ultraviolet rays are used for the active energy rays during complete curing, it is necessary to add them in a range that does not inhibit the polymerization reaction.

(Adhesive sheet with release sheet)
The pressure-sensitive adhesive sheet 1 of the present invention is obtained by semi-curing the pressure-sensitive adhesive layer 11 by heating, and contains at least a part of the monomer (B) and the polymerization initiator (D) in an unreacted state. It is.
The pressure-sensitive adhesive sheet 1 of the present invention can be obtained, for example, by applying a pressure-sensitive adhesive composition on the release sheet 12 to form a coating film, and heating the coating film to obtain a cured product. By heating the coating film, the reaction of the base polymer (A) and the crosslinking agent (C) proceeds to form a cured product (adhesive layer 11). That is, during heating, the polymerization reaction of the monomer (B) by the polymerization initiator (D) does not proceed or is slight in the coating film, so that the resulting cured product (adhesive layer 11) In the monomer, the monomer (B) and the polymerization initiator (D) contained in the pressure-sensitive adhesive composition remain. Therefore, the pressure-sensitive adhesive sheet 1 of the present invention has active energy ray curability. In order to bring the pressure-sensitive adhesive composition into a semi-cured state, it is preferable to perform an aging treatment in which the pressure-sensitive adhesive sheet is allowed to stand for a certain period at a certain temperature after removing the solvent after coating. The aging treatment can be performed, for example, by standing at 23 ° C. for 7 days.

The release sheet 12 is a release laminate sheet having a release sheet substrate and a release agent layer provided on one side of the release sheet substrate, or a polyolefin such as a polyethylene film or a polypropylene film as a low polarity substrate. A film is mentioned.
Papers and polymer films are used as the release sheet substrate in the peelable laminate sheet. As the release agent constituting the release agent layer, for example, a general-purpose addition type or condensation type silicone release agent or a long-chain alkyl group-containing compound is used.
The pressure-sensitive adhesive sheet of the present invention is obtained by curing (semi-curing) the pressure-sensitive adhesive composition by heating, and at least a part of the monomer (B) and the polymerization initiator (D) is in an unreacted state. A pressure-sensitive adhesive layer (X) comprising the pressure-sensitive adhesive contained therein is provided.
The thickness of the pressure-sensitive adhesive layer (X) can be appropriately set according to the use and the like, and is not particularly limited, but is usually in the range of 10 to 500 μm, and particularly preferably 20 to 350 μm. When the thickness is equal to or greater than the lower limit value, it is possible to sufficiently ensure the unevenness followability. An adhesive sheet can be easily manufactured as the thickness of adhesive layer (X) is below the said upper limit.
The Young's modulus of the pressure-sensitive adhesive layer (X) after semi-curing is preferably in the range of 0.01 to 0.30 [N / mm ² ], and 0.05 to 0.20 [N / mm ² ]. It is more preferable that it is in the range. If the Young's modulus is within the above range, the pressure-sensitive adhesive layer (X) tends to have a desirable hardness. In particular, if it is at least the lower limit value, it tends to be more difficult to cause the paste to protrude from the pressure-sensitive adhesive layer (X) and to deteriorate the workability. Moreover, if Young's modulus is below the said upper limit, there exists a tendency for adhesive layer (X) to show the level | step difference followability outstanding more easily. The Young's modulus can be adjusted within a desired range by adjusting the addition amount of the monomer.
In addition, Shimadzu Corporation autograph AGS-X was used for this measurement, and it measured with the pulling speed of 10 [mm / min].

The pressure-sensitive adhesive sheet of the present invention may be composed of only the pressure-sensitive adhesive layer (X), and is a laminate comprising other layers (hereinafter referred to as layer (Y)) other than the pressure-sensitive adhesive layer (X). May be. Examples of the layer (Y) include a pressure-sensitive adhesive layer other than the pressure-sensitive adhesive layer (X), a support, and a release sheet.
Examples of the support include polystyrene, styrene-acrylic copolymer, acrylic resin, polyethylene terephthalate, polycarbonate, polyetheretherketone, triacetylcellulose, and other plastic films; antireflection films, optical films such as electromagnetic wave shielding films, etc. Is mentioned.

The release sheet is a sheet having releasability on at least one side. As a release sheet, a peelable laminate sheet having a release sheet substrate and a release agent layer provided on one side of the release sheet substrate, or a polyolefin film such as a polyethylene film or a polypropylene film as a low polarity substrate Is mentioned.
Papers and polymer films are used as the release sheet substrate in the peelable laminate sheet. As the release agent constituting the release agent layer, for example, a general-purpose addition type or condensation type silicone release agent or a long-chain alkyl group-containing compound is used. In particular, an addition type silicone release agent having high reactivity is preferably used.
Specific examples of silicone release agents include BY24-4527 and SD-7220 manufactured by Toray Dow Corning Silicone, KS-3600, KS-774, and X62-2600 manufactured by Shin-Etsu Chemical Co., Ltd. Is mentioned. Further, the silicone release agent may contain a silicone resin which is an organosilicon compound having a SiO ₂ unit and a (CH ₃ ) ₃ SiO _1/2 unit or CH ₂ ═CH (CH ₃ ) SiO _1/2 unit. preferable. Specific examples of the silicone resin include BY24-843, SD-7292, SHR-1404 manufactured by Toray Dow Corning Silicone, KS-3800, X92-183 manufactured by Shin-Etsu Chemical Co., Ltd., and the like.

The release sheet 12 preferably has different peelability between the release sheet 12a and the release sheet 12b in order to facilitate peeling. That is, when the peelability from one side and the peelability from the other are different, it becomes easy to peel only the release sheet 12 having the higher peelability first. In that case, what is necessary is just to adjust the peelability of the peeling sheet 12 of the peeling sheet 12a and the peeling sheet 12b according to the bonding method and the bonding order.

Application of the pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer 11 can be performed using a known coating apparatus. Examples of the coating apparatus include a blade coater, an air knife coater, a roll coater, a bar coater, a gravure coater, a micro gravure coater, a rod blade coater, a lip coater, a die coater, and a curtain coater.

The pressure-sensitive adhesive sheet of the present invention may be a single-sided pressure-sensitive adhesive sheet or a double-sided pressure-sensitive adhesive sheet.
Examples of the single-sided pressure-sensitive adhesive sheet include a multilayer sheet in which a pressure-sensitive adhesive layer (X) is laminated on a support. A release sheet may be further laminated on the pressure-sensitive adhesive layer (X) of the multilayer sheet. Moreover, you may provide another layer between a support body and adhesive layer (X).
As a double-sided pressure-sensitive adhesive sheet, a single-layer sheet composed of a pressure-sensitive adhesive layer (X), a multilayer sheet in which a plurality of pressure-sensitive adhesive layers (X) are laminated, a pressure-sensitive adhesive layer other than the pressure-sensitive adhesive layer (X) and the pressure-sensitive adhesive layer (X) Laminated multilayer sheet, multilayer sheet with adhesive layer (X) laminated on both sides of the support, adhesive layer (X) laminated on one side of the support, and adhesive other than the adhesive layer (X) on the other side A multilayer sheet in which the agent layer is laminated, a multilayer sheet in which a release sheet is laminated on one side or both sides of the single layer sheet or the multilayer sheet, and the like.
As the double-sided sheet, a non-carrier type having no support or a transparent one as the support is preferable. Such a double-sided pressure-sensitive adhesive sheet can be suitably used for bonding optical members because the pressure-sensitive adhesive layer (X) itself has high transparency and also has excellent transparency as a whole pressure-sensitive adhesive sheet.
Among the above, a non-carrier type is preferable, a single layer sheet composed of the pressure-sensitive adhesive layer (X) or a multilayer sheet obtained by laminating a plurality of pressure-sensitive adhesive layers (X) is preferable, and a single-layer sheet composed of the pressure-sensitive adhesive layer (X). Particularly preferred.

The pressure-sensitive adhesive sheet is obtained, for example, by applying a pressure-sensitive adhesive composition on a release sheet to form a coating film, and heating the coating film to obtain a cured product. By heating the coating film, the reaction of the base polymer (A) and the crosslinking agent (C) proceeds to form a cured product (adhesive layer (X)).
The coating liquid contains a solvent. Examples of the solvent include methanol, ethanol, isopropanol, acetone, methyl ethyl ketone, toluene, n-hexane, n-butyl alcohol, methyl isobutyl ketone, methyl butyl ketone, ethyl butyl ketone, cyclohexanone, ethyl acetate, butyl acetate, propylene glycol monomethyl. Ether acetate, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, N-methyl-2-pyrrolidone and the like are used. These may be used alone or in combination of two or more.
The coating film can be heated using a known heating device such as a heating furnace or an infrared lamp.

The thickness of the pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1 of the present invention is preferably 10 to 500 μm, and more preferably 20 to 350 μm. If the thickness of the pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1 is equal to or greater than the lower limit value, the adhesive surface 22a of the decorative film 22 with the pressure-sensitive adhesive layer 11 or the contact surface 24a of the ITO glass substrate 24 with the pressure-sensitive adhesive layer 11 is used. Even if the printing level difference 23 is formed, the unevenness followability can be sufficiently secured. If the thickness of the pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1 is not more than the above upper limit value, the pressure-sensitive adhesive sheet 1 can be easily produced.

As a method of using the pressure-sensitive adhesive sheet 1 of the present invention, when the pressure-sensitive adhesive layer 11 of the double-sided pressure-sensitive adhesive sheet 1 is in a semi-cured state, the decorative film 22 and the ITO glass substrate 24 are bonded and irradiated with active energy rays. A method of completely curing the pressure-sensitive adhesive layer 11 is preferable.
The adherend is not particularly limited, and can be applied to any one that has been conventionally fixed or adhered using an adhesive sheet.
For example, the single-sided pressure-sensitive adhesive sheet can be used for protecting and fixing various members in the production process of various products.
The active energy ray can be irradiated from the decorative film side 22 or from the ITO glass substrate 24 side, but is preferably irradiated from the decorative film side 22.
Before irradiating the active energy ray, the pressure-sensitive adhesive layer 11 is soft because it is in a semi-cured state, and has excellent unevenness followability with respect to the adhesive surface with the pressure-sensitive adhesive layer 11 having the printing step 23. After the bonding, the adhesive layer 11 is completely cured with active energy rays, so that the cohesive force of the adhesive layer 11 is increased, the holding power of the adherend is improved, and the deformation / distortion of the decorative film 22 can be prevented. .
Examples of the active energy rays include ultraviolet rays, electron beams, visible rays, X-rays, ion rays and the like, and can be appropriately selected according to the polymerization initiator (D) contained in the pressure-sensitive adhesive layer. Among these, from the viewpoint of versatility, ultraviolet rays or electron beams are preferable, and ultraviolet rays are particularly preferable.
As the ultraviolet light source, for example, a high pressure mercury lamp, a low pressure mercury lamp, an ultrahigh pressure mercury lamp, a metal halide lamp, a carbon arc, a xenon arc, an electrodeless ultraviolet lamp, or the like can be used.
As the electron beam, for example, an electron beam emitted from various electron beam accelerators such as a cockloftwald type, a bandecraft type, a resonant transformation type, an insulating core transformer type, a linear type, a dynamitron type, and a high frequency type can be used.

(Laminate)
A laminated body can be produced by bonding a pair of optical members, at least one of which is an optical film, using the pressure-sensitive adhesive sheet 1 of the present invention.
An optical member is each component in optical products, such as a touch panel and an image display apparatus. As a constituent member of the touch panel, for example, an ITO film in which an ITO film is provided on a transparent resin film, an ITO glass in which an ITO film is provided on the surface of a glass plate, a transparent conductive film in which a transparent polymer film is coated with a conductive polymer, Examples thereof include a hard coat film and an anti-fingerprint film. Examples of the constituent member of the image display device include an antireflection film, an alignment film, a polarizing film, a retardation film, and a brightness enhancement film used in a liquid crystal display device.
Examples of materials used for these members include glass, polycarbonate, polyethylene terephthalate, polymethyl methacrylate, polyethylene naphthalate, cycloolefin polymer, triacetyl cellulose, polyimide, and cellulose acylate.
As a pair of optical members bonded by the pressure-sensitive adhesive sheet 1 of the present invention, bonding between ITO films inside the touch panel, bonding between the ITO film and ITO glass, bonding between the ITO film of the touch panel and the liquid crystal panel. Bonding of a cover glass and an ITO film, bonding of a cover glass and a decorative film, and the like can be mentioned.

When the pressure-sensitive adhesive sheet of the present invention is a double-sided pressure-sensitive adhesive sheet, it can be used for bonding two adherends. For example, a pair of adherends are bonded via an adhesive sheet, an active energy ray is irradiated in that state, and the adhesive layer (X) is completely cured, whereby the pair of adherends are interposed via a double-sided adhesive sheet. It can be set as the laminated body laminated | stacked.
In this case, an optical member is preferably used as the adherend.

Examples of bonding a pair of optical members with a double-sided PSA sheet include bonding between ITO films inside the touch panel, bonding between the ITO film and ITO glass, bonding between the ITO film on the touch panel and the liquid crystal panel, and cover Examples include bonding between glass and an ITO film, bonding between a cover glass and a decorative film, and the like.

(Function and effect)
The pressure-sensitive adhesive sheet 1 in the above embodiment has a soft semi-cured pressure-sensitive adhesive layer 11 before bonding. By bonding to the decorative film 22 or the ITO glass substrate 24 provided with the printing step 23 in this state, it is easy to ensure the unevenness followability with respect to the printing step 23. Next, by completely curing the pressure-sensitive adhesive layer 11 by irradiation with active energy rays, the adhesive force and the holding force can be increased, and deformation and distortion of the decorative film 22 can be prevented.
Furthermore, since it is possible to prevent deformation / distortion of the decorative film 22 while ensuring unevenness followability only by using the pressure-sensitive adhesive sheet 1 of the present invention, the process is simplified and the cost is reduced. Also useful.
In addition, this invention is not limited to the said embodiment.

The features of the present invention will be described more specifically with reference to examples and comparative examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.
The vapor pressure of the monomer (B), the vapor pressure and the surface tension of the solvent (E) are all values at 25 ° C.

(Adhesive sheet production method of Example 1)
The crosslinkable acrylic resin was prepared by solution polymerization in ethyl acetate. 2-hydroxyethyl acrylate monomer and n-butyl acrylate monomer were blended in a mass ratio of 1: 3, and AIBN (azobisisobutyronitrile) as a radical polymerization initiator was dissolved in the solution. The solution was heated to 60 ° C. and random copolymerized to obtain an acrylate copolymer. The solution viscosity at 23 ° C. of a 35% solution of this copolymer was 5500 mPa · s.

For 100 parts by mass of the crosslinkable acrylic resin, as the monofunctional monomer (B1) in the monomer (B), isostearyl acrylate (Osaka Organic Chemical Industry Co., Ltd., ISTA, vapor pressure: 0 Pa, melting point : <-50 ° C.) 20 parts by mass, trimethylolpropane ethylene oxide-modified triacrylate (manufactured by Toagosei Co., Ltd., Aronix M-360 (EOTMPTA)) as a polyfunctional monomer (B2), a crosslinking agent (C) 0.15 parts by mass of tolylene diisocyanate compound (manufactured by Nippon Polyurethane Industry Co., Ltd., Coronate L), 1-hydroxy-cyclohexyl-phenyl-ketone (BASF Japan Ltd.) as the polymerization initiator (D) , IRGACURE 184) was added, and ethyl acetate was used as the solvent (E) so that the concentration was 30% by mass. (Vapor pressure: 15 × 10 ³ Pa, surface tension 23.8 mN / m) was added. A pressure-sensitive adhesive solution was obtained as described above.

The thickness of the pressure-sensitive adhesive solution after drying is 150 μm on the first release sheet (polyethylene terephthalate film subjected to release treatment manufactured by Teijin DuPont Films Ltd.) using a doctor blade YD type manufactured by Yoshimitsu Seiki Co., Ltd. It was coated so that Then, it was made to dry at 100 degreeC for 3 minute (s) with a hot air dryer, the solvent was removed, and the adhesive layer of the semi-hardened state was obtained.
A second release sheet (manufactured by Teijin DuPont Films Co., Ltd.), which was subjected to a release treatment having a higher releasability than the first release sheet, was bonded to one side of the pressure-sensitive adhesive layer to obtain an adhesive sheet with a release sheet. .

Using the obtained pressure-sensitive adhesive sheet, a 100 μm-thick PET film having a 40 μm printing step and a 0.5 μm-thick soda glass are bonded so that the pressure-sensitive adhesive layer comes to the printing step side, and then autoclaved (40 ° C., 0.5 MPa) , 30 minutes), and then an accumulated light amount of 1000 mJ / cm ² was irradiated with an ultraviolet irradiator (ECS-301G1 manufactured by Eye Graphic Co., Ltd.) to obtain a laminate.

(Example 2)
Of the monomer (B), the monofunctional monomer (B1) is not added, and the polyfunctional monomer (B2) is 10 parts by mass of trimethylolpropane ethylene oxide-modified triacrylate, and the polymerization initiator (D). An adhesive sheet and a laminate were obtained in the same manner as in Example 1 except that the content was 1.1 parts by mass.

(Example 3)
Of the monomer (B), the monofunctional monomer (B1) is not added, but 30 parts by mass of trimethylolpropane ethylene oxide-modified triacrylate as the polyfunctional monomer (B2), the polymerization initiator (D) A pressure-sensitive adhesive sheet and a laminate were obtained in the same manner as in Example 1 except that the content was 1.3 parts by mass.

(Comparative Example 1)
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the monomer (B) and the polymerization initiator (D) were not added. Moreover, the laminated body was obtained like Example 1 except not implementing ultraviolet irradiation.

(Comparative Example 2)
The monomer (B) and the polymerization initiator (D) were not added, except that 100 parts by mass of ARUFON UP-1000 (Toagosei) as the plasticizer and 0.19 parts by mass of the crosslinking agent (C) were used. A pressure-sensitive adhesive sheet was obtained in the same manner as Example 1. Moreover, the laminated body was obtained like Example 1 except not implementing ultraviolet irradiation.

〔Evaluation methods〕
(Evaluation 1: Adhesive strength)
About the adhesive sheet obtained by the Example and the comparative example, 180 degree peeling adhesive strength (before UV irradiation versus glass adhesive strength) with respect to soda glass was measured according to JIS Z0237.
Furthermore, one side of the pressure-sensitive adhesive tape obtained in Examples and Comparative Examples was bonded to an optical PET film having a thickness of 100 μm, and subsequently bonded to soda glass having a thickness of 1 mm. Further, after carrying out an autoclave treatment (40 ° C., 0.5 MPa, 30 minutes), a laminated body was obtained by irradiating an integrated light amount of 1000 mJ / cm ² with an ultraviolet irradiator (ECS-301G1 manufactured by Eye Graphic Co., Ltd.). With respect to the laminate, the 180 ° peel adhesion to soda glass (after UV irradiation versus glass adhesion) was measured according to JIS Z0237.

(Evaluation 2: haze)
About the adhesive sheet obtained by the Example and the comparative example, haze (haze) was measured according to JISK7136.
The test piece was produced by the following method. One side of the obtained double-sided pressure-sensitive adhesive tape was bonded to an optical PET film having a thickness of 100 μm, and subsequently bonded to soda glass having a thickness of 1 mm. Further, after autoclaving (40 ° C., 0.5 MPa, 30 minutes), a test piece was obtained by irradiating an integrated light amount of 1000 mJ / cm ² with an ultraviolet irradiator (ECS-301G1 manufactured by Eye Graphic).
Those having a haze of 10% or more were rejected, and those having a haze of less than 10% were considered acceptable. By this method, it can be determined whether or not it can be used for a display device such as a liquid crystal display (LCD) or an input device used in combination with the display device such as a touch panel.

(Evaluation 3: Concavity and convexity followability)
The pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples were bonded so as to be in close contact with the printing surface of the printing step sheet, and subsequently bonded so as to be in close contact with the PET film (thickness 100 μm), temperature 40 ° C., pressure 0 A pressure release method at 5 MPa for 30 minutes was performed in an autoclave to produce a PET / adhesive sheet / printed step sheet laminate. The printed step portion of the laminate was observed with a microscope, and the unevenness followability was evaluated according to the following criteria.
◎: No bubbles at all ○: Several small bubbles △: There are bubbles ×: There are many bubbles

(Evaluation 4: Concavity and convexity durability)
The laminate was allowed to stand for 24 hours in an environment at 80 ° C., and was observed with a microscope for the presence of bubbles and peeling, and evaluated according to the following criteria.
◎: No bubbles at all ○: Several small bubbles △: There are bubbles ×: There are many bubbles

(Evaluation 5: Film deformation)
Evaluation Method The PET / adhesive sheet / printing step sheet laminate was observed from the PET film side to see if there was any distortion in the printing step part and the non-printing part, and evaluated according to the following criteria.
○: No distortion / deformation. Δ: Slight distortion / deformation.
×: Large distortion / deformation

As shown in the above results, in Examples 1 to 3, the adhesive strength after UV irradiation is higher than the adhesive strength before irradiation, and it can be seen that a completely cured adhesive layer is formed by UV irradiation. Moreover, the adhesive strength after UV irradiation is sufficiently high. Further, Examples 1 to 3 have high unevenness followability and unevenness followability, and deformation such as distortion is not observed in the film.
On the other hand, in Comparative Example 1, since the monomer (B) and the polymerization initiator (D) are not contained, the pressure-sensitive adhesive layer is completely cured, and the unevenness followability and unevenness followability are significantly deteriorated. ing. In addition, large distortion occurred in the film. In Comparative Example 2, the monomer (B) and the polymerization initiator (D) are not contained, but since the plasticizer is contained, the uneven follow-up property is obtained, but the uneven follow-up durability is remarkably deteriorated. ing. Moreover, the adhesive force also fell.

Example 4-1
With respect to 100 parts by mass of the base polymer (A) of Example 1, isobornyl acrylate (manufactured by Kyoeisha Chemical Co., Ltd., light acrylate IB-XA) as the monofunctional monomer (B1) of the monomer (B). ) As a polyfunctional monomer (B2) of the monomer (B), trimethylolpropane ethylene oxide-modified triacrylate (manufactured by Toagosei Co., Ltd., Aronix M-360, vapor pressure: 0 Pa, melting point: 30 parts by mass of <15 ° C), 0.1 part by mass of tolylene diisocyanate compound (manufactured by Nippon Polyurethane Industry Co., Ltd., Coronate L) as a crosslinking agent (C), and 1-hydroxy- as a polymerization initiator (D) 2 parts by mass of cyclohexyl-phenyl-ketone (manufactured by BASF Japan Ltd., IRGACURE 184) is added, and the solvent (E Ethyl acetate was added as to give an adhesive solution.

The thickness of the pressure-sensitive adhesive solution after drying onto the first release sheet (polyethylene terephthalate film subjected to mold release manufactured by Teijin DuPont Films Ltd.) using a doctor blade YD type manufactured by Yoshimitsu Seiki Co., Ltd. is 50 μm. It was coated so that Thereafter, the solvent was removed by drying at 100 ° C. for 3 minutes or 6 minutes with a hot air dryer to obtain a semi-cured pressure-sensitive adhesive layer.
A second release sheet (manufactured by Teijin DuPont Films Co., Ltd.) on which one side of the polyethylene terephthalate film has been subjected to a release treatment having a higher releasability than the first release sheet is bonded to this pressure-sensitive adhesive layer. Obtained.

(Example 4-2)
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 4-1, except that the monofunctional monomer (B1) of the monomer (B) was hexyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.).

(Example 4-3)
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 4-1, except that the monofunctional monomer (B1) of the monomer (B) was isooctyl acrylate (manufactured by Sigma Aldrich Japan).

(Example 4-4)
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 4-1, except that the monofunctional monomer (B1) of the monomer (B) was isodecyl acrylate (manufactured by Sartomer Japan KK, SR395).

(Example 4-5)
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 4-1, except that the monofunctional monomer (B1) of the monomer (B) was lauryl acrylate (manufactured by Sartomer Japan KK, SR335).

(Example 4-6)
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 4-3 except that the solvent (E) was acetone.

[Example 4-7]
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 4-3 except that the solvent (E) was toluene.

(Example 4-8)
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 4-3 except that the solvent (E) was cyclohexanone.

(Example 4-9)
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 4-1, except that the monofunctional monomer (B1) of the monomer (B) was stearyl acrylate (manufactured by Wako Pure Chemical Industries, Ltd.).

(Example 4-10)
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 4-1, except that the monofunctional monomer (B1) of the monomer (B) was ethyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.).

(Example 4-11)
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 4-1, except that the monofunctional monomer (B1) of the monomer (B) was changed to butyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.).

(Example 4-12)
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 4-3 except that the solvent (E) was hexane.

Table 2 shows the vapor pressure and melting point of the monofunctional monomer (B1) among the monomers (B) used in the above examples, and the vapor pressure and surface tension of the solvent (E).

Moreover, the following evaluation was performed about the obtained adhesive sheet. The results are shown in Table 3.

〔Evaluation methods〕
(Evaluation 1: Smoothness of coated surface)
The smoothness of the surface (coated surface) of the semi-cured pressure-sensitive adhesive layer before the second release sheet was bonded was visually observed. The level at which a smooth coated surface with no coating defects such as yuzu skin (orange peel) and Benard cell was obtained was accepted. If an unacceptable product is used for the display, a problem such as distortion in the image occurs.

(Evaluation 2: Adhesive strength)
With respect to the obtained pressure-sensitive adhesive sheets (with coating times of 3 minutes and 6 minutes), the 180 ° peel-off adhesion to soda glass (vs. glass adhesion) was measured according to JIS Z0237.
The test piece was produced by the same method as in Example 1.
The difference between the adhesive strength against glass when the drying time of the coating material was 3 minutes and 6 minutes and the average value thereof were calculated, and the ratio (%) of the difference to the average value was obtained. The adhesive strength difference <difference / average value> was 50% or more was rejected, and the adhesive strength difference was less than 50%. By this method, it is possible to determine whether or not the adhesive force, which is one of important performances, greatly changes due to subtle differences in drying conditions such as seasonal factors and is likely to affect the manufacturing yield.

(Evaluation 3: haze)
About the obtained adhesive sheet, haze (haze) was measured similarly to Example 1 according to JISK7136. Those having a haze of 10% or more were rejected, and those having a haze of less than 10% were considered acceptable.

As shown in the above results, in Examples 4-1 to 4-9, a smooth coated surface was formed. Moreover, the influence which the difference in drying conditions has on adhesive force was small. In particular, Examples 4-1 to 4-8, in which the melting point of the monomer (B) was 25 ° C. or less, had good haze of the pressure-sensitive adhesive sheet.
On the other hand, in Examples 4-1 to 4-9 using a monofunctional monomer having a low vapor pressure, a relatively smooth coated surface was formed, and fluctuations in adhesive strength due to differences in drying conditions were small.
A smoother coated surface was formed in the other examples than in Example 4-12 using the solvent (E) having a surface tension of less than 20 mmN / m.
Also, the unevenness tracking performance and film deformation prevention performance of Examples 4-1 to 4-12 were all good.

(Examples 5-1 to 5-7)
20 parts by mass of isostearyl acrylate (manufactured by Osaka Organic Chemical Co., Ltd., ISTA) as the monofunctional monomer (B1) out of the monomer (B) with respect to 100 parts by mass of the base polymer (A) of Example 1. Part, 4 parts by mass of trimethylolpropane triacrylate (manufactured by Toagosei Co., Ltd., Aronix M-321) as the polyfunctional monomer (B2) of the monomer (B), the crosslinking agent (C) (Nippon Polyurethane) 0.15 parts by mass of Coronate L-55E manufactured by Kogyo Co., Ltd. and 0.62 parts by mass of 1-hydroxy-cyclohexyl-phenyl-ketone (manufactured by BASF Japan Ltd., IRGACURE 184) as a polymerization initiator (D) 0.15 parts by mass of a silane coupling agent (manufactured by Soken Chemical Co., Ltd., C-50), 0.0025 parts by mass of a corrosion inhibitor (manufactured by Soken Chemical Co., Ltd., M), Concentration of ethyl acetate was added as the solvent (E) to be 33 mass%, to obtain an adhesive solution.
The thickness of the pressure-sensitive adhesive solution after drying onto the first release sheet (polyethylene terephthalate film subjected to mold release manufactured by Teijin DuPont Films Ltd.) using a doctor blade YD type manufactured by Yoshimitsu Seiki Co., Ltd. is 50 μm. It was coated so that Thereafter, the solvent was removed by drying at 100 ° C. for 3 minutes or 6 minutes with a hot air dryer to obtain a semi-cured pressure-sensitive adhesive layer.
A second release sheet (manufactured by Teijin DuPont Films Co., Ltd.) on which one side of the polyethylene terephthalate film has been subjected to a release treatment having a higher releasability than the first release sheet is bonded to this pressure-sensitive adhesive layer. Obtained.

The obtained adhesive sheet was subjected to holding force measurement according to JIS Z0237. Specifically, the holding force was measured according to the following procedure.
A 25 mm × 25 mm pressure-sensitive adhesive sheet was prepared, the second release sheet was peeled off, and the exposed pressure-sensitive adhesive surface was bonded to a PET film (Toyobo Co., Ltd. A4300 # 100) to prepare a test piece. Next, the first release sheet was peeled off, and the exposed adhesive surface was attached to a SUS plate (JIS G 4305, SUS304) and pressure-bonded with a 1 kg roller. After that, ultraviolet rays were irradiated with an ultraviolet irradiator (ECS-301G1 manufactured by Eye Graphic Co., Ltd.) so that the integrated light amount was 1000 mJ / cm ² . Next, one end of the test piece was clamped with a clasp so that the test piece was lowered vertically, a load of 1 kg was applied to the lower end, and the test piece was placed in an environment of 40 ° C. and relative humidity of 0 to 30%. The holding time was evaluated by measuring the time from when the load was applied until the test piece dropped from the SUS plate. The results are shown in Table 4.

As shown in the above results, in Examples 5-1, 5-2, 5-4, 5-5, and 5-7, the holding force was more excellent. From this, when the monomer (B) having an alkyl group having a chain length of 10 or more or the monomer (B) having a polycyclic structure is used, a further excellent holding power can be obtained. It was confirmed. Especially, when isostearyl acrylate was used as the monomer (B), particularly excellent holding power was obtained.
The concavo-convex tracking performance and film deformation prevention performance of Examples 5-1 to 5-7 were all good.

Throughout all the examples described above, the dynamic viscoelasticity of the fully cured adhesive layer after UV irradiation was in the range of 2 to 100 times that of the semicured dynamic viscoelasticity before irradiation. .

Since the pressure-sensitive adhesive sheet of the present invention has uneven tracking performance and film deformation prevention performance, it is useful for bonding a pair of optical members, for example, a touch panel module, at least one of which is a film.

1 Adhesive sheet (with release sheet)
11, 21 Adhesive layer 12a, 12b Release sheet 2 Touch panel module 22 Decorative film 22a Adhesive surface of the decorative film with the adhesive layer 23a, 23b, 23c, 23d Printing level difference (unevenness)
24 Plate substrate (ITO glass substrate)
24a Adhesive surface with adhesive layer of plate-like substrate (ITO glass substrate)

Claims (15)

1. A base polymer (A) containing a non-crosslinkable (meth) acrylic acid ester unit (a1) and an acrylic monomer unit (a2) having a crosslinkable functional group, and a monomer having at least one polymerizable unsaturated group A body (B), a crosslinking agent (C) that reacts with the base polymer (A) by heat, and a polymerization initiator (D) that initiates a polymerization reaction of the monomer (B) by irradiation with active energy rays. A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer (X) containing a pressure-sensitive adhesive obtained by semi-curing a pressure-sensitive adhesive composition containing a solvent (E) by heating.
2. The pressure-sensitive adhesive sheet according to claim 1, wherein the monomer (B) has an alkyl group having a chain length atom number of 10 or more.
3. The pressure-sensitive adhesive sheet according to claim 2, wherein the alkyl group has a chain length atom number of 15 to 22.
4. A base polymer (A) containing a non-crosslinkable (meth) acrylic acid ester unit (a1) and a crosslinkable functional group-containing acrylic monomer unit (a2), at least one polymerizable unsaturated group and a chain length atom A monomer (B) having an alkyl group having a number of 15 to 22, a crosslinking agent (C) that reacts with the base polymer (A) by heat, and the monomer (B) by irradiation with active energy rays A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer (X) containing a pressure-sensitive adhesive obtained by heating a pressure-sensitive adhesive composition containing a polymerization initiator (D) and a solvent (E).
5. The pressure-sensitive adhesive sheet according to any one of claims 1 to 4, wherein the monomer (B) is isostearyl acrylate.
6. The monomer (B) has a vapor pressure at 25 ° C. of 300 Pa or less,
   The pressure-sensitive adhesive sheet according to any one of claims 1 to 5, wherein the solvent (E) has a surface tension at 25 ° C of 20 mN / m or more and less than 40 mN / m.
7. The monomer (B) is a monofunctional monomer (B1) having one polymerizable unsaturated group having a melting point of 25 ° C. or lower and a polyfunctional monomer having two or more polymerizable unsaturated groups ( The pressure-sensitive adhesive sheet according to any one of claims 1 to 6, comprising at least one of B2).
8. The pressure-sensitive adhesive sheet according to any one of claims 1 to 7, wherein the monomer (B) has a polycyclic structure.
9. The pressure-sensitive adhesive sheet according to claim 8, wherein the monomer (B) is an acrylate having a bicyclo ring or a tricyclo ring.
10. The pressure-sensitive adhesive sheet according to any one of claims 1 to 9, wherein the solvent (E) does not have a polymerizable unsaturated group and has a higher vapor pressure at 25 ° C than the monomer (B).
11. 11. The solvent according to claim 1, wherein the solvent (E) comprises a solvent having a difference in solubility parameter from the monomer (B) within 2 [(cal / cm ³ ) ^1/2 ]. The pressure-sensitive adhesive sheet according to item.
12. The pressure-sensitive adhesive sheet according to any one of claims 1 to 11, which has a holding force measured in accordance with JIS 圧 着 Z0237 after being cured by press-bonding to an SUS plate and irradiating active energy rays.
13. The pressure-sensitive adhesive sheet according to any one of claims 1 to 12, which is a double-sided pressure-sensitive adhesive sheet.
14. The pressure-sensitive adhesive layer (X) of the pressure-sensitive adhesive sheet according to any one of claims 1 to 13 is brought into contact with the surface of the adherend, and in this state, the active energy ray is irradiated to completely form the pressure-sensitive adhesive layer (X). The manufacturing method of a laminated body including hardening.
15. A laminate obtained by bonding a pair of optical members via the pressure-sensitive adhesive sheet according to any one of claims 1 to 13, and irradiating active energy rays in that state to completely cure the pressure-sensitive adhesive layer (X). body.

Images