WO2022158121A1 - Adhesive sheet curable by active energy rays, adhesive sheet laminate that includes release film, adhesive sheet, laminate for configuring image display device, and image display device - Google Patents

Abstract

An adhesive sheet curable by active energy rays that does not readily soften or swell even when penetrated by an oily component such as sebum, that moreover can exhibit exceptional fluidity when affixed to an adherend, and that furthermore can exhibit reliable foaming resistance after having been laminated on an adherend and cured. Proposed by the present invention as said adhesive sheet is an adhesive sheet curable by active energy rays that comprises an adhesive agent layer containing a (meth)acrylic polymer (A) and that satisfies requirements (1) and (2).　(1) The thickness is 0.8-1.5 m, and the strain (creep strain) after a pressure of 1,000 Pa has been applied for 1,200 seconds at a temperature of 50°C is 150-1,500%.　(2) The oil and fat swelling rate derived according to formula (i) is 30% or less, where So is the initial surface area of the adhesive sheet, and St is the surface area after the adhesive sheet has been immersed in an artificial sebum liquid (a mixture in which squalene/oleic acid = 1/1) for four days at 25°C.　Formula (i): (Oil and fat swelling rate (%))=(St−So)/So×100

Description

Active energy ray-curable adhesive sheet, adhesive sheet laminate with release film, adhesive sheet, laminate for constituting image display device, and image display device

The present invention provides an active energy ray-curable pressure-sensitive adhesive sheet having the property of being cured by an active energy ray, a pressure-sensitive adhesive sheet laminate with a release film, a pressure-sensitive adhesive sheet, a laminate for constituting an image display device, and an image display device using the same. Regarding.

In recent years, in order to improve the visibility of image display devices, image display panels such as liquid crystal displays (LCD), plasma displays (PDP), electroluminescence displays (ELD), and protection placed on the front side (visible side) The gap between the panel and the touch panel member is filled with an adhesive sheet, a liquid adhesive, or the like to suppress the reflection of incident light or emitted light from the display image at the interface of the air layer.

As a method for filling the gaps between the constituent members for such an image display device with an adhesive, for example, Patent Document 1 discloses a method for filling the gaps with a liquid adhesive adhesive composition containing an ultraviolet-curable resin, followed by applying an ultraviolet ray. is disclosed for curing by irradiation.

Also known is a method of filling gaps between constituent members for an image display device using an adhesive sheet. For example, in Patent Document 2, as a method for producing a laminate for image display device construction, which has a configuration in which image display device constituent members are laminated on at least one side of a transparent double-sided adhesive sheet, a pressure-sensitive adhesive sheet primarily crosslinked with ultraviolet light is disclosed. is adhered to an image display device constituent member, and then the adhesive sheet is irradiated with ultraviolet rays through the image display device constituent member for secondary curing.

In Patent Document 3, a pressure-sensitive adhesive sheet containing a pressure-sensitive adhesive composition containing an acrylic copolymer composed of a graft copolymer having a macromonomer as a branch component, a cross-linking agent, and a photopolymerization initiator is used. A method is disclosed in which, after adhering image display device constituent members, active energy rays are irradiated through the image display device constituent members to crosslink the pressure-sensitive adhesive composition, thereby adhering the image display device constituent members.

Patent Document 4 discloses a photocurable pressure-sensitive adhesive sheet used for bonding a resin member (X) having a light transmittance of 10% or less at a wavelength of 365 nm and a light transmittance of 60% or more at a wavelength of 405 nm. and a photocurable pressure-sensitive adhesive sheet characterized by having a pressure-sensitive adhesive layer (Y) having all of the following properties (1) to (3).
(1) The gel fraction (referred to as "gel fraction before light irradiation X1") is in the range of 0 to 60%.
(2) The light transmittance at a wavelength of 390 nm is 89% or less and the light transmittance at a wavelength of 410 nm is 80% or more.
(3) It has a photo-curing property that cures when irradiated with light having a wavelength of 405 nm.

Also, in recent years, the following problems have arisen when using laptops, tablets, and smartphones. That is, there are many opportunities for a person's finger or the like to come into contact with the housing or the image display screen, and oily ingredients such as sebum and cosmetics exist on the surface of the skin in addition to sweat, so during long-term use, In some cases, for example, it gradually penetrates from the edge of the joint between the protective panel and the housing, and even penetrates into the adhesive layer of the double-sided adhesive tape. Since the oily component has the effect of softening and swelling the adhesive, there arises a problem that the adhesive composition of the adhesive sheet protrudes from the edges of the adherend.

In order to solve this problem, Patent Document 5 discloses a double-sided pressure-sensitive adhesive tape in which the pressure-sensitive adhesive is less likely to soften and swell even when an oily component such as sebum permeates. is composed of an acrylic pressure-sensitive adhesive composition containing an acrylic copolymer having n-butyl acrylate and a vinyl monomer having a polar group as monomer components, and n in the monomer component forming the acrylic copolymer - an oil-resistant double-sided pressure-sensitive adhesive tape having a butyl acrylate content of 70% by mass or more is disclosed.

International Publication 2010/027041 Japanese Patent No. 4971529 International Publication 2015/137178 JP 2019-210445 A JP 2009-215355 A

In Patent Documents 1 to 4, the voids between the members constituting the image display device (also referred to as "image display device constituent members") can be filled, and step absorption can be obtained. There is a demand for step absorbability for image display device constituent members having uneven steps.
That is, the surface of the constituent members of the image display device may be roughened by wiring, printing, pattern development, etching, perforating, surface treatment, or the like. In recent years, image display devices such as mobile phones tend to be designed to display almost the entire area of the image display panel. In order to place the camera inside, a hole is provided in the functional layer such as a polarizing film or a reflective film laminated on the surface of the image display panel according to the position and size of the camera. The pressure-sensitive adhesive sheet for bonding image display device components having holes is required to have a property (high fluidity) that allows the pressure-sensitive adhesive to flow into the holes and fill every corner.
In addition, in Patent Documents 1 to 4, the penetration of oily components such as sebum is not improved, and both high fluidity and oil resistance are insufficient. In Literature 5, although it has a certain degree of oil resistance effect, it is still unsatisfactory in terms of compatibility with high fluidity.
If the pressure-sensitive adhesive sheet for bonding image display device constituent members having such a stepped portion cannot follow the irregularities and fill every corner, air bubbles may be generated inside the pressure-sensitive adhesive layer, or the image may become uneven. The pressure-sensitive adhesive sheet is required to have high fluidity because the constituent members of the display device may be distorted or deformed.
However, it has been difficult to exhibit high fluidity at the time of lamination while suppressing softening and swelling due to permeation of oily components.

Therefore, the present invention has excellent oil resistance such that even when an oily component such as sebum penetrates, it does not soften or swell and protrude from the edges of the adherend, and furthermore, the adherend adheres to the adherend. Active energy ray-curable pressure-sensitive adhesive sheet capable of absorbing unevenness by flowing into unevenness, even if the surface has unevenness, for example, bottomed holes, and laminate for constituting image display device and image using the same The object is to provide a display device.

The present invention proposes an active energy ray-curable pressure-sensitive adhesive sheet that has a pressure-sensitive adhesive layer containing a (meth)acrylic polymer (A) and satisfies the following requirements (1) and (2).
(1) The thickness is 0.8 to 1.5 mm, and the strain (creep strain) after applying a pressure of 1000 Pa at a temperature of 50° C. for 1200 seconds is 150% or more and 1500% or less.
(2) Let So be the initial area of the adhesive sheet, and St be the area after immersing the adhesive sheet in artificial sebum solution (squalene:oleic acid = 1:1 mixture) at 25°C for 4 days. The fat and oil swelling ratio determined by the formula (i) is 30% or less.
Oil swelling rate (%) = [(St-So) / So] × 100 (i)

The present invention also proposes a release film-attached pressure-sensitive adhesive sheet laminate having a configuration in which the active energy ray-curable pressure-sensitive adhesive sheet proposed by the present invention and a release film are laminated.

The present invention also provides an image having a structure in which two members constituting an image display device are laminated via an active energy ray-curable pressure-sensitive adhesive sheet having a fat swelling ratio of 30% or less as determined by the following formula (i). A laminate for constituting a display device,
The pressure-sensitive adhesive sheet comprises a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive resin composition containing a (meth)acrylic polymer (A), and has a thickness of 0.8 to 1.5 mm and a temperature of 50 ° C. A laminated body for constituting an image display device is proposed, in which a strain (creep strain) after applying a pressure of 1000 Pa for 1200 seconds is 150% or more and 1500% or less.
Oil swelling rate (%) = [(St-So) / So] × 100 (i)
In formula (i), So is the initial area of the adhesive sheet, and St is the area after immersing the adhesive sheet in an artificial sebum solution (squalene:oleic acid = 1:1 mixture) at 25 ° C. for 4 days. be.

In the present invention, two constituent members of an image display device are laminated via a cured pressure-sensitive adhesive sheet obtained by curing an active energy ray-curable pressure-sensitive adhesive sheet having a fat swelling rate of 30% or less as determined by the following formula (i). A laminate for image display device configuration, comprising:
The pressure-sensitive adhesive sheet has a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive composition containing a (meth)acrylic polymer (A), and has a thickness of 0.8 to 1.5 mm, a temperature of 80 ° C., and a temperature of 1000 Pa. is applied for 180 seconds with a strain (creep strain) of 5% or more and 220% or less.
Oil swelling rate (%) = [(St-So) / So] × 100 (i)
In formula (i), So is the initial area of the adhesive sheet, and St is the area after immersing the adhesive sheet in an artificial sebum solution (squalene:oleic acid = 1:1 mixture) at 25 ° C. for 4 days. be.

The present invention also proposes an image display device configured using the laminate for configuring an image display device.

The active energy ray-curable pressure-sensitive adhesive sheet proposed by the present invention has excellent oil resistance. For example, even when an oily component such as sebum permeates, it softens and swells and does not protrude from the edges of the adherend. do not have.
In addition, the active energy ray-curable pressure-sensitive adhesive sheet proposed by the present invention can exhibit excellent fluidity when it is attached to an adherend by heating, and the adherend surface of the adherend has unevenness. For example, even if there is a hole with a bottom, it can flow into the unevenness and absorb the unevenness.

Next, the present invention will be described based on an embodiment. However, the present invention is not limited to the embodiments described below.

<This adhesive sheet>
A pressure-sensitive adhesive sheet (referred to as "the present pressure-sensitive adhesive sheet") according to an example of the embodiment of the present invention includes a pressure-sensitive adhesive layer containing a (meth)acrylic polymer (A) as a main component resin (referred to as "the present pressure-sensitive adhesive layer") It is a sexual energy ray-curable pressure-sensitive adhesive sheet.

<This adhesive layer>
The present pressure-sensitive adhesive layer in the present pressure-sensitive adhesive sheet includes, for example, a (meth)acrylic polymer (A), optionally a cross-linking agent (B) and/or a polymerization initiator (C), and optionally other It can be formed from a pressure-sensitive adhesive composition (referred to as the "present pressure-sensitive adhesive composition") comprising the components. The pressure-sensitive adhesive composition preferably contains the (meth)acrylic polymer (A) as a main component resin.

The "active energy ray-curable adhesive sheet" is a pressure-sensitive adhesive sheet having properties that can be cured by an active energy ray, in other words, an active energy ray-curable adhesive sheet that leaves room for curing by an active energy ray. is the meaning of
This pressure-sensitive adhesive sheet may have been cured (also referred to as “temporary curing”) in a state in which there is room for curing by the active energy ray, or may have not been cured at all (referred to as “uncured”). ) and can be cured by active energy rays.
If the adhesive sheet is temporarily cured or uncured, the adhesive sheet is cured with active energy rays before or after bonding the adhesive sheet to the adherend ("main curing ), which can result in increased cohesion and improved adhesion.

In addition, the "main component resin" means the resin having the highest mass ratio among the resins constituting the pressure-sensitive adhesive layer or the pressure-sensitive adhesive composition. The content of the main component resin is 50 mass % or more, especially 60 mass % or more, 70 mass % or more, 75 mass % or more (100 mass % ).

(Gel fraction)
The pressure-sensitive adhesive sheet is in a non-crosslinked state or a slightly crosslinked state, ie, a gel fraction of 0% or more and 20% or less, before being cured by an active energy ray.
From the viewpoint of conformability to irregularities on the adherend surface, the gel fraction is preferably 10% or less, more preferably 8% or less, and even more preferably 5% or less.

In addition, when the present pressure-sensitive adhesive sheet is cured by irradiating an active energy ray with a wavelength of 365 nm at an accumulated light amount of 4000 mJ/cm ² , the gel fraction increases compared to before curing, and the gel fraction is 10% or more and 80% or less. It is preferable that
When the gel fraction is 10% or more after curing with active energy rays, shape stability of the pressure-sensitive adhesive sheet and shape stability and durability when formed into a laminate can be imparted.
From this point of view, the gel fraction after curing with active energy rays is preferably 10% or more, more preferably 30% or more, more preferably 40% or more, and more preferably 50% or more.
On the other hand, the gel fraction after active energy ray curing is preferably 80% or less. Since the gel fraction is 80% or less, it has moderate flexibility even after curing with active energy rays, and the image display device configuration when the image display device configuration laminate is stored in a high-temperature or low-temperature environment. It can follow the dimensional change of the member without foaming. From this point of view, it is more preferably 75% or less, and more preferably 70% or less.

In this pressure-sensitive adhesive sheet, in order to adjust the gel fraction after curing within the above range, the composition and molecular weight of the (meth)acrylic polymer (A), which is the base polymer, may be adjusted, or the cross-linking agent (B) may be added. It is preferable to adjust the amount, or to adjust the intensity of the active energy ray to be irradiated and the integrated amount of light. However, it is not limited to this means.

<Lamination structure>
The present pressure-sensitive adhesive sheet may have a single-layer structure composed of the present pressure-sensitive adhesive layer, or may have a multi-layer structure of two or more layers provided with the present pressure-sensitive adhesive layer.
When the pressure-sensitive adhesive sheet has a multilayer structure of two or more layers, it is preferable that at least the outermost layer, the backmost layer, or both layers correspond to the pressure-sensitive adhesive layer. All the layers may be layers corresponding to the pressure-sensitive adhesive layer.

<Thickness>
The thickness of the adhesive sheet is preferably 10 μm to 500 μm, more preferably 15 μm or more and 400 μm or less, and even more preferably 20 μm or more and 350 μm or less.

When the pressure-sensitive adhesive sheet has a multi-layer structure of two or more layers, the thickness of the layer corresponding to the pressure-sensitive adhesive layer preferably accounts for 20 to 100% of the total thickness of the pressure-sensitive adhesive sheet, especially 30% or more. Alternatively, it accounts for 95% or less, more preferably 40% or more or 90% or less.

<Creep characteristics>
The adhesive sheet preferably has a thickness of 0.8 to 1.5 mm and a strain (creep strain) of 150% or more and 1500% or less after applying a pressure of 1000 Pa at a temperature of 50° C. for 1200 seconds.
In the present adhesive sheet, the fact that the creep strain at 50° C. is 150% or more indicates that it is easily deformed in a heated state. It is preferable because it can be filled. From this point of view, the strain is more preferably 160% or more, more preferably 180% or more, and even more preferably 200% or more.
On the other hand, if the creep strain at 50°C is 1500% or less, it is preferable from the viewpoint of excellent dimensional stability of the PSA sheet. From this point of view, the strain is more preferably 1400% or less, more preferably 1300% or less, and even more preferably 1200% or less.

As described above, the creep strain in the present pressure-sensitive adhesive sheet is a numerical value when the thickness is 0.8 mm to 1.5 mm. It is necessary to avoid fluctuations in measurement results due to the influence of measurement jigs due to insufficient thickness. To this end, it is necessary to measure the present pressure-sensitive adhesive sheet after adjusting it within a certain range of thickness.
By adjusting the thickness of the pressure-sensitive adhesive sheet in advance within the above range and then measuring the creep strain, the creep strain of the pressure-sensitive adhesive sheet can be accurately determined without being affected by the measuring jig.

The above-mentioned "thickness of 0.8 to 1.5 mm" means that if the thickness of the adhesive sheet as a measurement sample is less than this range, the thickness of the measurement sample is adjusted by stacking several sheets. It means to adjust to the range. The same is true when the thickness of the measurement sample is specified in other tests.

In this pressure-sensitive adhesive sheet, in order to adjust the creep strain within the above range, the composition and molecular weight of the (meth)acrylic polymer (A), which is the base polymer described later, may be adjusted, or the amount of the cross-linking agent (B) added may be adjusted. It is preferable to adjust However, it is not limited to this means.

In addition, when this adhesive sheet is cured by irradiating an active energy ray with a wavelength of 365 nm with an accumulated light amount of 4000 mJ/cm ² , the adhesive sheet after curing has a thickness of 0.8 to 1.5 mm and a temperature of 80 ° C. and a pressure of 1000 Pa. is applied for 180 seconds, the strain (creep strain) is preferably 5% or more and 220% or less.
In the present pressure-sensitive adhesive sheet, the fact that the strain (creep strain) after applying a pressure of 1000 Pa at a temperature of 80° C. for 180 seconds after curing is 5% or more means that even after curing, it is easy to deform at high temperatures and stress Since it shows that it has excellent relaxation properties, even if the size of the adherend changes due to changes in temperature after bonding to the adherend, it can follow without causing foaming or peeling at the interface with the adherend. It is preferable in that durability can be obtained.
From this point of view, the creep strain after curing with active energy rays is more preferably 7% or more, more preferably 10% or more, more preferably 15% or more.
On the other hand, if the upper limit of the strain (creep strain) after curing is too high, the adhesive sheet may protrude from the end face of the laminate in a high temperature environment and the end face may become sticky. The creep strain in is preferably 220% or less, more preferably 100% or less, further preferably 80% or less, especially 60% or less, 40% or less, 30% or less more preferred.
Especially, when the upper limit of the strain (creep strain) after curing is 80% or less, durability in high-temperature environments and low-temperature environments can be obtained, and the glue protrudes from the edges of the adhesive sheet. The occurrence of in-plane bubbles and the like is suppressed. Also from this point, the upper limit is preferably 70% or less, more preferably 60% or less, still more preferably 40% or less, and particularly preferably 30% or less.

It should be noted that the creep strain of the present pressure-sensitive adhesive sheet after curing with active energy rays is also measured after adjusting the thickness of the present pressure-sensitive adhesive sheet to 0.8 mm to 1.5 mm in the same manner as described above. As described above, is based on consideration of the influence of the measuring jig, and is not intended to require the thickness of the pressure-sensitive adhesive sheet to be within the above range.

In this pressure-sensitive adhesive sheet, in order to adjust the creep strain after active energy ray curing within the above range, the composition and molecular weight of the (meth)acrylic polymer (A), which is the main component resin, may be adjusted, or the cross-linking agent (B ) is preferably adjusted and the amount of active energy ray irradiation is adjusted. However, it is not limited to this means.

<Oil swelling rate>
The initial area of the pressure-sensitive adhesive sheet is So, and the area after immersing the pressure-sensitive adhesive sheet in an artificial sebum solution (squalene:oleic acid = 1:1 mixture) at 25°C for 4 days is St. It is preferable that the oil swelling ratio determined by the formula (i) is 30% or less.
Oil swelling rate (%) = [(St-So) / So] × 100 (i)

The shape of the pressure-sensitive adhesive sheet used for measuring the fat swelling rate is arbitrary.
As a method for measuring the area, for example, if the pressure-sensitive adhesive sheet is polygonal, circular, or the like, it can be calculated from the outer peripheral dimension or the like. It can also be obtained by performing image processing and analyzing the pressure-sensitive adhesive sheet to be measured.

If the oil swelling rate of the present pressure-sensitive adhesive sheet is 30% or less, even if an oily component such as sebum permeates, the pressure-sensitive adhesive sheet is less likely to soften and swell, and can exhibit excellent oil resistance.
From this point of view, the fat swelling ratio of the adhesive sheet is more preferably 25% or less, more preferably 20% or less, more preferably 15% or less, even more preferably 10% or less.

In addition, when the pressure-sensitive adhesive sheet is cured by irradiating it with an active energy ray having a wavelength of 365 nm with an accumulated amount of light of 4000 mJ/cm ² , it is preferable that the swelling rate of oils and fats after curing is 30% or less. If the oil swelling rate after hardening is 30% or less, even if an oily component such as sebum penetrates, it is difficult to soften and swell, and excellent oil resistance can be exhibited.
From this point of view, the oil swelling rate after curing of the adhesive sheet is preferably 30% or less, more preferably 28% or less, more preferably 25% or less.

In order to adjust the swelling rate of fats and oils in the pressure-sensitive adhesive sheet within the above range, for example, the composition of the (meth)acrylic polymer (A), which is the base polymer described later, includes, for example, a vinyl monomer having a polar group and butyl acrylate. Adjust the composition ratio of alkyl (meth) acrylate having a relatively short number of carbon atoms in the alkyl group such as (for example, 6 or less), adjust the structure and addition amount of the cross-linking agent (B), or adjust the irradiation amount of the active energy ray etc. should be adjusted. However, it is not limited to these methods.

<Adhesive strength>
The pressure-sensitive adhesive sheet has an adhesive strength to soda lime glass, that is, the pressure-sensitive adhesive sheet is roll-bonded to soda lime glass by reciprocating the roll once, cured at 60 ° C. for 30 minutes, and then at 23 ° C. and 40% RH. When the pressure-sensitive adhesive sheet is peeled off from the soda-lime glass at a peeling angle of 180° and a peeling speed of 60 mm/min, the 180° peeling force to the glass is preferably 2 N/cm or more.
If the peeling force is 2 N/cm, the positioning and temporary fixation of the later-described image display device constituent members are facilitated. In addition, an effect of suppressing permeation of oily components such as sebum can be obtained.
From this point of view, the 180° peeling force is preferably 2 N/cm or more, more preferably 4 N/cm or more, more preferably 5 N or more, and even more preferably 10 N/cm or more. preferable. Although the upper limit of the peeling force is not particularly limited, it is usually 20 N/cm.

This pressure-sensitive adhesive sheet also has an adhesive strength when cured after being laminated to soda-lime glass, that is, the pressure-sensitive adhesive sheet is roll-bonded to soda-lime glass by reciprocating the roll once, cured at 60 ° C. for 30 minutes, The pressure-sensitive adhesive sheet was cured by irradiating an active energy ray with a wavelength of 365 nm so that the cumulative amount of light was 4000 mJ/cm ² , cured at 23° C. for 15 hours, and then peeled at a peel angle of 180° at 23° C. and 40% RH. It is preferable that the adhesive sheet is peeled off from the soda-lime glass at a peeling speed of 60 mm/min and has a 180° peeling force to the glass of 2 N/cm or more.
If the peeling force is 2 N/cm, it is preferable because it suppresses permeation of an oily component such as sebum and improves durability when a layered product is formed by laminating it to an image display device constituent member described later.
From this point of view, the peel force when the soda lime glass is laminated and then irradiated with an active energy ray is preferably 2 N/cm or more, more preferably 3 N/cm or more, and 5 N/cm or more. more preferably 10 N/cm or more. Although the upper limit of the peeling force is not particularly limited, it is usually 20 N/cm.

<Present adhesive composition>
In addition to the (meth)acrylic polymer (A), the present pressure-sensitive adhesive composition preferably contains a cross-linking agent (B) and/or a polymerization initiator (C), and optionally a silane coupling agent (D). , and other ingredients.

((Meth) acrylic polymer (A))
The present pressure-sensitive adhesive composition contains a (meth)acrylic polymer (A), especially as a main component resin. That is, it is the resin having the highest mass ratio among the resins constituting the present pressure-sensitive adhesive composition. At this time, among the resins constituting the present pressure-sensitive adhesive composition, the mass ratio of the (meth)acrylic polymer (A) is 50% by mass or more, especially 70% by mass or more, especially 80% by mass or more, especially 90% by mass. % or more (including 100% by mass).

As the (meth)acrylic polymer (A), the following formula 1 (wherein R ₁ represents a hydrogen atom or a methyl group and R ₂ represents a linear or branched alkyl group having 1 to 18 carbon atoms or represents an alicyclic hydrocarbon group), and is preferably obtained by polymerizing a polymer component containing 35% by mass or more of the monomer component.

Among them, the (meth)acrylic polymer (A) is more preferably a polymer containing 40% by mass or more of the monomer component as a polymerization component, more preferably a polymer containing 50% by mass or more, and among them 60% by mass. % or more is particularly preferred.

In the present invention, "(meth)acrylic" means acrylic and methacrylic, "(meth)acryloyl" means acryloyl and methacryloyl, and "(meth)acrylate" means acrylate and methacrylate, respectively. and "(co)polymer" is meant to include polymers and copolymers.

Examples of the monomer represented by Formula 1 include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, neopentyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate , heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, Decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (Meth)acrylate, isobornyl (meth)acrylate, 3,5,5-trimethylcyclohexane (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate and the like. These may be used singly or in combination of two or more. These can be used singly or in combination of two or more.

Among these, from the viewpoint of imparting durability to oily components to the adhesive, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, n-butyl (Meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, neopentyl (meth)acrylate, hexyl (meth)acrylate , cyclohexyl (meth)acrylate and other alkyl (meth)acrylates having 6 or less carbon atoms in the alkyl group, particularly methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, i - propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, neopentyl It is more preferable to include alkyl (meth)acrylates having 5 or less carbon atoms in the alkyl group such as (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl (meth)acrylate, n - Alkyl (meth)acrylates having 2 to 4 carbon atoms in the alkyl group such as butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, t-butyl (meth)acrylate, etc. More preferred is n-butyl (meth)acrylate.

The (meth)acrylic polymer (A) is preferably a copolymer having "another copolymerizable monomer" other than the monomer component as a copolymerization component.

The above-mentioned "other copolymerizable monomer" is preferably contained in the (meth)acrylic polymer (A) in an amount of 1 to 60% by mass, especially in a proportion of 2% by mass or more or 50% by mass or less. is more preferable, and among them, it is more preferable to be contained at a ratio of 3% by mass or more or 40% by mass or less.

Examples of the "other copolymerizable monomer" include (a) a carboxyl group-containing monomer (hereinafter also referred to as "copolymerizable monomer a1"), (b) a hydroxyl group-containing monomer (hereinafter also referred to as "copolymerizable monomer a2"). ), (c) amino group-containing monomer (hereinafter also referred to as “copolymerizable monomer a3”), (d) epoxy group-containing monomer (hereinafter also referred to as “copolymerizable monomer a4”), (e) amide Group-containing monomer (hereinafter also referred to as "copolymerizable monomer a5"), (f) vinyl monomer (hereinafter also referred to as "copolymerizable monomer a6"), (g) macromonomer (hereinafter also referred to as "copolymerizable monomer a7" ), (h) an aromatic-containing monomer (hereinafter referred to as "copolymerizable monomer a8"), and (i) other functional group-containing monomer (hereinafter referred to as "copolymerizable monomer a9"). These can be used singly or in combination of two or more.

Examples of the copolymerizable monomer a1 include (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypropyl (meth)acrylate, carboxybutyl (meth)acrylate, ω-carboxypolycaprolactone mono(meth)acrylate, 2- (Meth) acryloyloxyethyl hexahydrophthalate, 2-(meth) acryloyloxypropyl hexahydrophthalate, 2-(meth) acryloyloxyethyl phthalate, 2-(meth) acryloyloxypropyl phthalate, 2-(meth) ) acryloyloxyethyl maleate, 2-(meth)acryloyloxypropyl maleate, 2-(meth)acryloyloxyethyl succinate, 2-(meth)acryloyloxypropyl succinate, crotonic acid, fumaric acid, maleic acid, itacon Mention may be made of acids. These may be used alone or in combination of two or more.

Examples of the copolymerizable monomer a2 include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxy-1-methylethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, glycerin mono(meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, polyethylene glycol polypropylene glycol mono(meth)acrylate , polyethylene glycol polybutylene glycol mono(meth)acrylate, polypropylene glycol polybutylene glycol mono(meth)acrylate, hydroxyphenyl (meth)acrylate and other hydroxy group-containing (meth)acrylates. These may be used alone or in combination of two or more.

Examples of the copolymerizable monomer a3 include aminoalkyl (meth)acrylates such as aminomethyl (meth)acrylate, aminoethyl (meth)acrylate, aminopropyl (meth)acrylate, aminoisopropyl (meth)acrylate, N-alkylamino Examples include N,N-dialkylaminoalkyl (meth)acrylates such as alkyl (meth)acrylates, N,N-dimethylaminoethyl (meth)acrylate, and N,N-dimethylaminopropyl (meth)acrylate. These may be used alone or in combination of two or more.

Examples of the copolymerizable monomer a4 include glycidyl (meth)acrylate, methylglycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate glycidyl ether. . These may be used alone or in combination of two or more.

Examples of the copolymerizable monomer a5 include (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-butyl(meth)acrylamide, N-methylol(meth)acrylamide, N-methylolpropane(meth)acrylamide, Mention may be made of N-methoxymethyl(meth)acrylamide, N-butoxymethyl(meth)acrylamide, diacetone(meth)acrylamide, maleic acid amide and maleimide. These may be used alone or in combination of two or more.

Examples of the copolymerizable monomer a6 include compounds having a vinyl group in the molecule. Examples of such compounds include functional monomers having functional groups such as alkoxylalkyl groups such as ethoxydiethylene glycol acrylate, methoxytriethylene glycol acrylate, methoxypolyethylene glycol acrylate, methoxydipropylene glycol acrylate, and methoxypolypropylene glycol acrylate. and polyalkylene glycol di(meth)acrylates and vinyl ester monomers such as vinyl acetate, N-vinyl-2-pyrrolidone, vinyl propionate and vinyl laurate, and styrene, chlorostyrene, chloromethylstyrene, α-methylstyrene and Other aromatic vinyl monomers such as substituted styrene can be exemplified. These may be used alone or in combination of two or more.

The macromonomer as the copolymerizable monomer a7 is a polymer monomer having a terminal radically polymerizable unsaturated group and a high molecular weight skeleton component. The number average molecular weight of the macromonomer is preferably 1,000 or more, more preferably 1,500 or more, and even more preferably 2,000 or more. The upper limit of the number average molecular weight is usually 10,000.

By using the copolymerizable monomer a7, a macromonomer can be introduced as a branch component of the graft copolymer, and the (meth)acrylic acid ester copolymer can be made into a graft copolymer. For example, it can be a (meth)acrylic polymer (A) comprising a graft copolymer having a macromonomer as a branch component.
Therefore, the properties of the graft copolymer can be changed by selecting the copolymerizable monomer a7 and the other monomers and their mixing ratio.
In particular, in the present invention, the copolymerization ratio of the macromonomer in the (meth)acrylic polymer (A) is 10 parts by mass or less per 100 parts by mass of the copolymer to impart fluidity during hot-melting. point, more preferably 3 parts by mass or more or 9 parts by mass or less, and particularly preferably 4 parts by mass or more or 8 parts by mass or less.

The skeleton component of the macromonomer is preferably composed of a (meth)acrylic acid ester polymer or a vinyl polymer. For example, linear or branched alkyl (meth)acrylates, alicyclic (meth)acrylates, the copolymerizable monomers a1, the copolymerizable monomers a2, and the copolymerizable monomers a6, in which the alkyl group has 1 to 18 carbon atoms. , copolymerizable monomers a8, etc., which will be described later, and these can be used alone or in combination of two or more.

Examples of the copolymerizable monomer a8 include benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, nonylphenol EO-modified (meth)acrylate, and the like. These may be used alone or in combination of two or more.

Examples of the copolymerizable monomer a9 include (meth)acryl-modified silicone, 2-acryloyloxyethyl acid phosphate, 2,2,2-trifluoroethyl (meth)acrylate, 2,2,3,3-tetra Fluoropropyl (meth)acrylate, 2,2,3,3-tetrafluoropropyl (meth)acrylate, 1H,1H,5H-octafluoropentyl (meth)acrylate, 1H,1H,2H,2H-tridecafluoro-n - fluorine-containing monomers such as octyl (meth)acrylate; These may be used alone or in combination of two or more.

The (meth)acrylic polymer (A) preferably does not contain or substantially does not contain the "copolymerizable monomer a1" from the viewpoint of metal corrosion resistance and yellowing resistance.
In addition, "does not contain or substantially does not contain copolymerizable monomer a1" means not only the case where it does not contain completely, but also the case where copolymerizable monomer a1 is contained in the (meth)acrylic acid ester (co)polymer. It is intended to allow a content of less than 0.5% by mass, preferably less than 0.1% by mass.

The (meth)acrylic polymer (A) preferably contains a vinyl monomer having a polar group from the viewpoint of imparting durability to an oily component, adhesion strength and cohesive strength to the pressure-sensitive adhesive, and among these, a hydroxyl group. It preferably contains a containing monomer and/or a nitrogen atom-containing monomer. That is, the (meth)acrylic polymer (A) contains the "copolymerizable monomer a2", "copolymerizable monomer a3" and "copolymerizable monomer a5", especially "copolymerizable monomer a2", Those having it as a copolymer component are particularly preferred.

The (meth)acrylic polymer (A) is preferably a block copolymer and/or a graft copolymer from the viewpoint of imparting hot-melt properties to the pressure-sensitive adhesive.
Here, the block copolymer is a block copolymer having a plurality of polymer chains containing repeating units derived from (meth)acrylate ester, and in which a plurality of polymer chains having different chemical structures are linearly bonded. Say.
Here, the graft copolymer is a copolymer containing repeating units derived from (meth)acrylic acid ester as a trunk component and repeating units derived from a macromonomer as a branch component of the graft copolymer. are preferred, and those containing a graft copolymer are particularly preferred.

In the present invention, the flexibility of the pressure-sensitive adhesive sheet at room temperature and the wettability of the pressure-sensitive adhesive resin composition to the adherend, that is, the adhesiveness, are affected. In order to have appropriate adhesiveness (tackiness), the glass transition temperature of the (meth)acrylic polymer (A) is preferably −70° C. to 0° C., especially −65° C. or higher or −5° C. ° C. or lower, among which -60 °C or higher or -10 °C or lower is particularly preferred.

In this case, the glass transition temperature of the copolymer component means a value calculated by Fox's formula from the glass transition temperature of the polymer obtained from the homopolymer of each component of the copolymer and the composition ratio.

The Fox calculation formula is a calculated value obtained by the following formula, which is described in Polymer Handbook [Polymer Handbook, J. Am. Brandrup, Interscience, 1989].
1/(273+Tg)=Σ(Wi/(273+Tgi))
[In the formula, Wi is the weight fraction of the monomer i, and Tgi is the Tg (° C.) of the homopolymer of the monomer i. ]

When obtaining the (meth)acrylic copolymer (A), the glass transition temperature of at least one of the (meth)acrylic acid ester-derived repeating units of the acrylic polymer (A) is − 70 to 0°C is preferred.
(Meth)acrylic acid esters constituting such repeating units include, for example, n-butyl acrylate, n-hexyl acrylate, n-octyl acrylate, n-nonyl acrylate, n-decyl acrylate, 2-ethylhexyl acrylate, 2 -ethylhexyl methacrylate, 2-methylhexyl acrylate, isooctyl acrylate, isononyl acrylate, isodecyl acrylate, isodecyl methacrylate, isostearyl acrylate, isostearyl methacrylate, multi-branched stearyl acrylate, multi-branched stearyl methacrylate, and the like. , but not limited to these.

Further, it is preferable that the glass transition temperature of at least one of the (meth)acrylic acid ester-derived repeating units contained in the acrylic copolymer (A) is 5 to 140°C. Specifically, the glass transition temperature (Tg) is preferably 5 to 140°C, more preferably 30 to 130°C, more preferably 40°C, because it affects the hot-melt temperature of the pressure-sensitive adhesive sheet. or higher or 120° C. or lower, more preferably 50° C. or higher or 110° C. or lower.
If there is a repeating unit having such a glass transition temperature (Tg), excellent workability and storage stability can be maintained by adjusting the molecular weight, and hot-melt can be performed at a predetermined temperature, for example, around 20 to 80 ° C. can be adjusted to

(Meth)acrylic acid esters constituting such repeating units include, for example, methyl (meth)acrylate, ethyl methacrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl methacrylate, t-butyl (meth) acrylate, isobutyl (meth) acrylate, isobornyl (meth) acrylate, cyclohexyl (meth) acrylate, 1,4-cyclohexanedimethanol mono (meth) acrylate, tetrahydrofurfuryl methacrylate, benzyl (meth) acrylate, phenoxyethyl ( Meth)acrylate, the above-mentioned copolymerizable monomer a7, and the like can be mentioned. etc. can be mentioned.

In the present invention, by using a block copolymer or a graft copolymer as the (meth)acrylic polymer (A), the pressure-sensitive adhesive sheet can have excellent shape stability and hot-melt properties. Block copolymers and graft copolymers can be produced by known methods, and graft copolymers in particular can be produced by using a macromonomer as a copolymer component as described above.

Here, the block copolymer refers to a copolymer having a plurality of polymer chains containing repeating units derived from (meth)acrylic acid ester, and having a plurality of polymer chains with different chemical structures bonded in a straight chain. Say.
It is preferable that some blocks of the block copolymer contain repeating units derived from the macromonomer.
On the other hand, graft copolymers are copolymers containing repeating units derived from (meth)acrylic acid ester as a trunk component, and depending on the method of introducing the branch component, they can be comb-shaped polymers, brush-shaped polymers, star polymers, palm-shaped polymers, and so on. It refers to those with structures such as polymers and dumbbell polymers.
A copolymer containing repeating units derived from a macromonomer as a branch component of the graft copolymer is preferred.

When the (meth)acrylic polymer (A) is a copolymer containing structural units derived from a macromonomer as described above, from the viewpoint of imparting hot-melt properties, per 100 parts by mass of the copolymer Therefore, it is preferable to contain 3 to 10 parts by mass of the macromonomer. When the copolymerization ratio of the macromonomer is 3 parts by mass or more with respect to 100 parts by mass of the copolymer, it is preferable from the viewpoint of suppressing excessive flow during storage or hot melting, and on the other hand, when it is 10 parts by mass or less. , is preferred from the viewpoint of imparting fluidity during hot-melting.
From this point of view, the copolymerization ratio of the macromonomer is preferably 3 parts by mass or more, more preferably 4 parts by mass or more. On the other hand, it is preferably 10 parts by weight or less, especially 9 parts by weight or less, especially 8 parts by weight or less, and even more preferably less than 7 parts by weight.

The glass transition temperature of the repeating unit derived from the macromonomer is preferably 20 to 150°C, more preferably 40°C or higher or 130°C or lower, and more preferably 60°C or higher or 120°C or lower.
In the case where the (meth)acrylic polymer (A) is a block copolymer and/or a graft copolymer, the content of the copolymer component having a glass transition temperature within the above range is For the same reason as above, the amount is preferably 3 parts by mass or more, more preferably 4 parts by mass or more, relative to 100 parts by mass of the (meth)acrylic polymer (A). On the other hand, it is preferably 10 parts by weight or less, especially 9 parts by weight or less, especially 8 parts by weight or less, and even more preferably less than 7 parts by weight.

The (meth)acrylic polymer (A) preferably contains "an alkyl (meth)acrylate having an alkyl group having 6 or less carbon atoms" and "a vinyl monomer having a polar group" as monomer components.
At this time, the content of the "alkyl (meth)acrylate having 6 or less carbon atoms in the alkyl group" in the monomer component forming the acrylic polymer (A) is preferably 40% by mass or more. It is preferable that the content of the "vinyl monomer having
In order to achieve oil resistance, that is, to suppress the penetration of oily components and the swelling caused by oily components, it is preferable to contain a "vinyl monomer containing a polar group" as a monomer component for forming the acrylic copolymer (A). On the other hand, as the number of polar groups in the (meth)acrylic polymer (A) increases, the cohesive force of the pressure-sensitive adhesive sheet increases, and hot-melt properties tend to decrease. In addition, the polar groups or the polar groups and other components react with each other due to heating or the like, causing gradual gelation, which may impair the quality stability of the pressure-sensitive adhesive sheet. Thus, it is difficult to achieve both oil resistance and hot-melt properties at a high quality level.
However, if the (meth)acrylic polymer (A) has such a composition, it is possible to achieve both hot-melt properties while suppressing the penetration of the oily component into the present pressure-sensitive adhesive sheet and the swelling of the present pressure-sensitive adhesive sheet due to the oily component. It is preferable because it can
From this point of view, the content of the "alkyl (meth)acrylate having 6 or less carbon atoms in the alkyl group" in the monomer component forming the (meth)acrylic polymer (A) is preferably 40% by mass or more. , especially 90% by mass or less, more preferably 45% by mass or more or 85% by mass or less.
The content of the "vinyl monomer having a polar group" is preferably 2 parts by mass or more, and preferably 3 parts by mass or more, relative to 100 parts by mass of the (meth)acrylic polymer (A). More preferably, it is 5 parts by mass or more, and particularly preferably 10 parts by mass or more. On the other hand, it is preferably 50 parts by mass or less, more preferably 45 parts by mass or less, among which 40 parts by mass or less, among which 35 parts by mass or less, further among these 30 parts by mass or less, further among these 25 parts by mass Part or less is particularly preferred.

(Crosslinking agent (B))
The cross-linking agent (B) is a compound or composition capable of causing a polymerization reaction or a cross-linking reaction by a radical reaction caused by an active energy ray and bonding with a (meth)acrylic polymer.
A cross-linking agent (B) is a compound having two or more cross-linkable functional groups.
When the present pressure-sensitive adhesive composition contains the cross-linking agent (B), the present pressure-sensitive adhesive composition forms a cross-linked structure, and the durability and oil resistance of the present pressure-sensitive adhesive sheet can be enhanced.

The cross-linking agent (B) is preferably a polyfunctional (meth)acrylate having a cyclic structure from the viewpoint of suppressing swelling due to the oily component after forming the cross-linking structure.

The cross-linking agent (B) is a polyfunctional (meth)acrylate component (b-1) having two or more (meth)acryloyl groups, from the viewpoint of securing the property that the pressure-sensitive adhesive sheet is cured by being irradiated with an active energy ray. ) is preferably included. Moreover, from the viewpoint of improving followability to thermal dimensional change of the adherend, it is preferable to further include a monofunctional (meth)acrylate component (b-2) having one (meth)acryloyl group.

By including a polyfunctional (meth)acrylate component (b-1) having two or more (meth)acryloyl groups as a cross-linking agent (B) in the pressure-sensitive adhesive composition, the pressure-sensitive adhesive composition forms a crosslinked structure. Then, the cross-linking reaction of the (meth)acrylic polymer (A) can be accelerated, and the curing of the pressure-sensitive adhesive composition can be accelerated. Furthermore, by containing a monofunctional (meth)acrylate component (b-2) having one (meth)acryloyl group, the molecular weight between crosslink points of the cured product can be increased, so that the degree of freedom of movement of the molecular chains is increased. In addition, when the adherend is laminated via the present pressure-sensitive adhesive sheet, even when the adherend is dimensionally deformed due to repeated heating and cooling, the present pressure-sensitive adhesive sheet made of the present pressure-sensitive adhesive composition can be used for that purpose. It can be deformed accordingly.

From this point of view, it is preferable to include a polyfunctional (meth)acrylate component (b-1) and a monofunctional (meth)acrylate component (b-2). In such a case, the content ratio by mass is preferably (b-1):(b-2)=1:0.1 to 1:9, more preferably 1:1 to 1:9, A ratio of 1:2 to 1:9 is more preferred. Within this range, the amount of the monofunctional (meth)acrylate component (b-2) is not too large, and the sensitivity to light is not likely to decrease, resulting in a decrease in productivity, and the adherend can be sufficiently adhered.

The content of the cross-linking agent (B) is preferably 0.2 parts by mass or more, especially 0.5 parts by mass or more, with respect to 100 parts by mass of the (meth)acrylic polymer (A). Among them, 1 part by mass or more is more preferable. The upper limit is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, and more preferably 20 parts by mass or less.
In addition, the content of the polyfunctional (meth)acrylate component (b-1) is a (meth)acrylic polymer from the viewpoint of forming a crosslinked structure and imparting swelling resistance and cohesive strength due to the oily component after curing. The content of (A) is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, more preferably 1.5 parts by mass or more, particularly preferably 6 parts by mass or more, based on 100 parts by mass of (A). The upper limit is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, particularly preferably 10 parts by mass or less.
The content of the monofunctional (meth)acrylate component (b-2) is 100 parts by mass of the (meth)acrylic polymer (A) from the viewpoint of adjusting the crosslink density and imparting appropriate flexibility to the cured product. On the other hand, it is preferably 2 parts by mass or more, more preferably 4 parts by mass or more, particularly preferably 6 parts by mass or more. The upper limit is preferably 20 parts by mass or less, more preferably 18 parts by mass or less, particularly preferably 15 parts by mass or less.

The polyfunctional (meth)acrylate component (b-1) is preferably a component having a glass transition temperature higher than 0° C. when converted into a homopolymer, more preferably 5° C. or higher, and more preferably 10° C. or higher. preferable. The upper limit is usually 250°C.
On the other hand, the monofunctional (meth)acrylate component (b-2) is preferably a component having a glass transition temperature of 0° C. or lower when converted into a homopolymer, especially -10° C. or lower, especially -20° C. or lower. It is more preferable to have The lower limit is usually -80°C.
By containing a monofunctional (meth)acrylate component (b-2) with a low glass transition temperature, it becomes loose and hard even when cured, so that it deforms according to the dimensional change of the adherend. Even in repeated endurance tests, it is possible to suppress the occurrence of peeling and air bubbles.
Here, the glass transition temperature means the maximum value of loss tangent (tan δ) obtained by dynamic viscoelasticity measurement at a frequency of 1 Hz.

Examples of the polyfunctional (meth)acrylate component (b-1) include 1,4-butanediol di(meth)acrylate, glycerin di(meth)acrylate, neopentyl glycol di(meth)acrylate, glycerin glycidyl ether di(meth)acrylate, ) acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, tricyclodecanedimethanol di(meth)acrylate, adamantanediol di(meth)acrylate, adamantanedimethanol di(meth)acrylate (Meth)acrylates, dicyclopentadiene di(meth)acrylate, adamantanetriol tri(meth)acrylate, adamantane trimethanol tri(meth)acrylate, cyclohexanedimethanol di(meth)acrylate, dioxane glycol di(meth)acrylate, spiro glycol Di(meth)acrylate, fluorene di(meth)acrylate, bisphenol A polyethoxydi(meth)acrylate, bisphenol A polypropoxydi(meth)acrylate, bisphenol F polyethoxydi(meth)acrylate, ethylene glycol di(meth)acrylate, neopentyl glycol Di (meth) acrylate, trimethylolpropane trioxyethyl (meth) acrylate, ε-caprolactone-modified tris (2-hydroxyethyl) isocyanurate tri (meth) acrylate, pentaerythritol tri (meth) acrylate, propoxylated pentaerythritol tri ( meth)acrylate, ethoxylated pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, propoxylated pentaerythritol tetra(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate , polyethylene glycol di(meth)acrylate, tris(acryloxyethyl)isocyanurate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate, tripentaerythritol hexa(meth)acrylate, tripentaerythritol penta( meth)acrylate, neopentyl glycol hydroxybivalate di(meth)acrylate, di(meth)acrylate of ε-caprolactone adduct of neopentyl hydroxybivalate In addition to UV-curable polyfunctional (meth)acrylic monomers such as acrylate, trimethylolpropane tri(meth)acrylate, trimethylolpropane polyethoxytri(meth)acrylate, and ditrimethylolpropane tetra(meth)acrylate, polyester (meth) ) polyfunctional (meth)acrylic oligomers such as acrylate, epoxy (meth)acrylate, urethane (meth)acrylate and polyether (meth)acrylate. These may be used singly or in combination of two or more.

Among these, tricyclodecanedimethanol di(meth)acrylate, adamantanediol di(meth)acrylate, adamantanedimethanol di(meth)acrylate, dicyclopentadiene di(meth)acrylate from the viewpoint of preventing swelling due to oily components. , adamantanetriol tri(meth)acrylate, adamantane trimethanol tri(meth)acrylate, cyclohexanedimethanol di(meth)acrylate, dioxane glycol di(meth)acrylate, spiroglycol di(meth)acrylate, fluorene (meth)acrylate, Bisphenol A polyethoxydi(meth)acrylate, bisphenol A polypropoxydi(meth)acrylate, bisphenol F polyethoxydi(meth)acrylate, ε-caprolactone-modified tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, tris(acryloxyethyl) ) Preferred are (meth)acrylates having a cyclic structure such as isocyanurate, among which tricyclodecanedimethanol di(meth)acrylate, adamantanediol di(meth)acrylate and adamantanedimethanol having an alicyclic or heterocyclic structure Di(meth)acrylate, dicyclopentadiene di(meth)acrylate, adamantanetriol tri(meth)acrylate, adamantane trimethanol tri(meth)acrylate, cyclohexanedimethanol di(meth)acrylate, dioxane glycol di(meth)acrylate, spiro Glycol di(meth)acrylate is more preferred, and tricyclodecanedimethanol di(meth)acrylate having an alicyclic structure, adamantanediol di(meth)acrylate, adamantanedimethanol di(meth)acrylate, dicyclopentadiene di(meth)acrylate, (Meth)acrylates are more preferred.

Examples of the monofunctional (meth)acrylate component (b-2) include ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl ( meth) acrylate, amyl (meth) acrylate, isoamyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, decyl (meth) acrylate, isodecyl ( meth)acrylate, dodecyl (meth)acrylate, isododecyl (meth)acrylate, tetradecyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, behenyl (meth)acrylate, cyclopropyl (meth)acrylate, cyclobutyl (meth)acrylate, cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, cycloheptyl (meth)acrylate, cyclooctyl (meth)acrylate, cyclononyl (meth)acrylate, cyclodecyl (meth)acrylate, isobornyl (meth)acrylate, norbornyl (meth)acrylate, adamantyl (meth)acrylate, tricyclodecanedimethanol acrylate, ethoxylated-o-phenylphenol acrylate, 2-hydroxy-o-phenylphenolpropyl acrylate, methoxypolyethylene glycol (meth)acrylate, methoxypolypropylene glycol (meth) acrylate, polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, phenoxyethylene glycol (meth) acrylate, phenoxydiethylene glycol (meth) acrylate, phenoxy polyethylene glycol (meth) acrylate, 2-hydroxy-o-phenylphenol propyl acrylate, 2-(meth)acryloyloxyethyl succinic acid, 2-(meth)acryloyloxyethyl tetrahydrophthalic acid, 2-(meth)acryloyloxyethyl hexahydrophthalic acid, 2-(meth)acryloyloxypropyl phthalic acid, 2-(meth)acryloyloxypropylhydrophthalic acid, 2-(meth)acryloyloxypropylhexahydrophthalic acid, etc. benzyl (meth)acrylate, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, phenoxyethylene glycol (meth) acrylate, 2-naphthyl (meth) acrylate, 9-anthracenyl (meth) acrylate, 1-pyrenylmethyl (meth) acrylate, benzyl (meth) acrylate, Tricyclodecane dimethanol monoacrylate monocarboxylic acid, dicyclopentanyl acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) ) acrylate, 4-hydroxybutyl (meth) acrylate, trimethylolpropane mono (meth) acrylate, glycerin mono (meth) acrylate, pentaerythritol mono (meth) acrylate, diglycerin mono (meth) acrylate, ditrimethylolpropane mono (meth) ) acrylate, dipentaerythritol mono(meth)acrylate, ethoxylated trimethylolpropane mono(meth)acrylate, propoxylated trimethylolpropane mono(meth)acrylate, ethoxylated glycerol mono(meth)acrylate, propoxylated glycerol mono(meth)acrylate Acrylates, ethoxylated pentaerythritol mono(meth)acrylate, propoxylated pentaerythritol mono(meth)acrylate, ethoxylated ditrimethylolpropane mono(meth)acrylate, propoxylated ditrimethylolpropane mono(meth)acrylate, alkylene oxide-modified diglycerin mono In addition to (meth)acrylate and alkylene oxide-modified dipentaerythritol mono(meth)acrylate, monofunctional oligomers such as monofunctional urethane (meth)acrylate, monofunctional epoxy (meth)acrylate, monofunctional polyester (meth)acrylate, etc. can be mentioned. These may be used singly or in combination of two or more.

<Polymerization initiator (C)>
The polymerization initiator (C) should just be a compound which generates a radical by an active energy ray.
The polymerization initiator (C) is roughly classified into two groups according to the mechanism of radical generation. and a hydrogen abstraction type photoinitiator capable of forming an exciplex with a hydrogen donor inside and transferring hydrogen of the hydrogen donor.

The polymerization initiator (C) may be either a cleavage photoinitiator or a hydrogen abstraction photoinitiator, each of which may be used alone or a mixture of both may be used. may be used alone or in combination of two or more.

Examples of cleavage-type photoinitiators include 2,2-dimethoxy-1,2-diphenylethan-1-one, 1-hydroxycyclohexylphenylketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one. , 1-(4-(2-hydroxyethoxy)phenyl)-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-[4-{4-(2-hydroxy-2- Methyl-propionyl)benzyl}phenyl]-2-methyl-propan-1-one, oligo(2-hydroxy-2-methyl-1-(4-(1-methylvinyl)phenyl)propanone), phenylglyoxylic acid methyl, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butan-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one , 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone, bis(2,4,6-trimethylbenzoyl)-phenyl Phosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, (2,4,6-trimethylbenzoyl)ethoxyphenylphosphine oxide, bis(2,6-dimethoxybenzoyl) 2,4,4-trimethylpentylphosphine Fin oxides and their derivatives can be mentioned.

Hydrogen abstraction photoinitiators include, for example, benzophenone, 4-methyl-benzophenone, 2,4,6-trimethylbenzophenone, 4-phenylbenzophenone, 3,3'-dimethyl-4-methoxybenzophenone, 4-(meth)acryloyl Oxybenzophenone, methyl 2-benzoylbenzoate, methyl benzoylformate, bis(2-phenyl-2-oxoacetic acid)oxybisethylene, 4-(1,3-acryloyl-1,4,7,10,13-pentaoxo tridecyl)benzophenone, thioxanthone, 2-chlorothioxanthone, 3-methylthioxanthone, 2,4-dimethylthioxanthone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone and derivatives thereof, etc. can be mentioned.

The content of the polymerization initiator (C) is not particularly limited. As a guideline, it is contained in a ratio of 0.1 to 10 parts by mass, especially 0.5 to 5 parts by mass, and among them 1 to 3 parts by mass based on 100 parts by mass of the (meth)acrylic polymer (A). is preferred.

<Silane coupling agent (D)>
The silane coupling agent (D) can improve adhesion, especially adhesion to glass materials.

Examples of the silane coupling agent include compounds having a hydrolyzable functional group such as an alkoxy group together with an unsaturated group such as a vinyl group, an acryloxy group and a methacryloxy group, an amino group, an epoxy group, and the like. .
Specific examples of silane coupling agents include N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane, γ-aminopropyl Examples include triethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and the like.
Among them, γ-glycidoxypropyltrimethoxysilane or γ-methacryloxypropyltrimethoxysilane is preferably used in the present pressure-sensitive adhesive layer from the viewpoints of good adhesion and little discoloration such as yellowing. be able to.
The silane coupling agents may be used singly or in combination of two or more.

The content of the silane coupling agent (D) is preferably 0.1 to 5 parts by mass, preferably 0.2 to 3 parts by mass with respect to 100 parts by mass of the (meth)acrylic polymer (A). More preferably:
Coupling agents such as organic titanate compounds can also be effectively used in the same manner as silane coupling agents.

<Other ingredients>
"Other components" other than those described above contained in the present pressure-sensitive adhesive composition include, for example, tackifier resins, antioxidants, light stabilizers, metal deactivators, anti-aging agents, moisture absorbing agents, if necessary. Various additives such as agents, polymerization inhibitors, ultraviolet absorbers, rust preventives, and inorganic particles can be incorporated as appropriate.
Moreover, if necessary, a reaction catalyst such as a tertiary amine compound, a quaternary ammonium compound, a tin laurate compound, or the like may be appropriately contained.

(block copolymer or graft copolymer)
In order to impart hot-melt properties to the present pressure-sensitive adhesive sheet, the present pressure-sensitive adhesive composition contains a block copolymer and/or a graft copolymer as a polymer other than the (meth)acrylic polymer (A). can contain. These copolymers preferably have at least one rubbery segment and at least one glassy segment.

Here, the block copolymer refers to a block copolymer having a plurality of polymer chains containing repeating units derived from a certain monomer and having a plurality of polymer chains having different chemical structures bonded in a linear fashion. .
A graft copolymer is a copolymer containing a repeating unit derived from a monomer as a trunk component and a repeating unit derived from a monomer different from the trunk component as a branch component of the graft copolymer. means coalescence.

The rubbery segment is a moiety that exhibits a glass transition temperature (Tg) below room temperature, preferably below 0°C, more preferably below -10°C, and even more preferably below -20°C.
Examples of monomers constituting the rubber-like segment include conjugated dienes and hydrogenated derivatives of conjugated dienes. Here, the conjugated diene preferably contains 4 to 12 carbon atoms.
Examples of conjugated dienes include butadiene, isoprene, ethylbutadiene, phenylbutadiene, piperylene, pentadiene, hexadiene, ethylhexadiene, and dimethylbutadiene. The polymerized conjugated dienes can be used individually or with each other as copolymers. In some embodiments, the conjugated diene is selected from the group consisting of isoprene, butadiene, ethylene-butadiene copolymers, and combinations thereof.

A glassy segment is a portion that exhibits a Tg above room temperature. The glassy segment has a Tg of 40° C. or higher, preferably 60° C. or higher, more preferably 80° C. or higher.
Monomers constituting the glassy segment include, but are not limited to, monovinyl aromatic monomers. For example, monovinyl aromatic monomers include styrene, vinylpyridine, vinyltoluene, α-methylstyrene, methylstyrene, dimethylstyrene, ethylstyrene, diethylstyrene, t-butylstyrene, di-n-butylstyrene, isopropylstyrene, and others. Included are alkylated styrenes, styrene analogues, and styrene analogues.

The content of the block copolymer other than the (meth)acrylic polymer (A) and/or the graft copolymer is 1 part by mass or more per 100 parts by mass of the (meth)acrylic polymer (A). Among them, 2 parts by mass or more, more preferably 5 parts by mass or more. The upper limit is preferably 100 parts by mass or less, more preferably 95 parts by mass or less, and more preferably 90 parts by mass or less.

(Plasticizer)
The present pressure-sensitive adhesive composition can contain a plasticizer in order to impart hot-melt properties to the present pressure-sensitive adhesive sheet.

Non-limiting examples of plasticizers. Examples include those selected from the group consisting of polyisobutylene, polyisoprene, polybutadiene, amorphous polyolefins and copolymers thereof, silicones, polyacrylates, oligomeric polyurethanes, ethylene propylene copolymers, any combination or mixture thereof. .
Among these, the plasticizer is preferably polyisobutylene. Examples of polyisobutylene plasticizers that may be used herein include those marketed by BASF under the tradename OPPANOL, particularly those selected from the OPPANOLB series.

From the viewpoint of environmental protection, the volatile organic compound (VOC) value of the plasticizer used is preferably as small as possible, preferably less than 1000 ppm, more preferably less than 800 ppm, and even more preferably less than 600 ppm when measured by thermogravimetric analysis. , less than 400 ppm is most preferred.

The content mass of the plasticizer is not particularly limited. It is preferably 0.1 to 20 parts by mass, more preferably 0.5 to 15 parts by mass, based on 100 parts by mass of the (meth)acrylic polymer (A).

(Hydrocarbon tackifier)
The present pressure-sensitive adhesive composition can contain a hydrocarbon tackifier in order to impart hot-melt properties to the present pressure-sensitive adhesive sheet.
Hydrocarbon tackifiers include terpene resins such as polyterpenes (e.g., α-pinene-based resins, β-pinene-based resins, and limonene-based resins) and aromatic-modified polyterpene resins (e.g., phenol-modified polyterpene resins), and coumaran-indene resins. , and petroleum-based resins such as C5-based hydrocarbon resins, C9-based hydrocarbon resins, C5/C9-based hydrocarbon resins, and dicyclopentadiene-based resins, modified rosins, hydrogenated rosins, polymerized rosins, rosins such as rosin esters. can be mentioned.
The hydrocarbon tackifier is preferably compatible with the present pressure sensitive adhesive composition.

The content of the hydrocarbon tackifier is not particularly limited. It is preferably 0.1 to 40 parts by mass, more preferably 0.5 to 20 parts by mass, based on 100 parts by mass of the (meth)acrylic polymer (A).

By including these plasticizers and hydrocarbon tackifiers, it is possible to suitably prepare a hot-melt adhesive composition having adhesive properties.

<Method for preparing the present pressure-sensitive adhesive composition>
In addition to the (meth)acrylic polymer (A), the present pressure-sensitive adhesive composition preferably contains a cross-linking agent (B) and/or a polymerization initiator (C), and optionally a silane coupling agent (D). , and other components in predetermined amounts.
The mixing method of these components is not particularly limited, and the mixing order of each component is also not particularly limited.
Also, a heat treatment step may be added during the production of the pressure-sensitive adhesive composition. In this case, it is desirable to heat-treat after mixing each component of the pressure-sensitive adhesive composition in advance. A masterbatch obtained by concentrating various mixed components may be used.

Also, the device for mixing is not particularly limited, and for example, a universal kneader, planetary mixer, Banbury mixer, kneader, gate mixer, pressure kneader, three rolls, and two rolls can be used. You may mix using a solvent as needed.
In addition, this pressure-sensitive adhesive composition can be used as a solvent-free system that does not contain a solvent. When used as a solvent-free system, no solvent remains and the advantage of improved heat resistance and light resistance can be provided.

<Layers other than this adhesive layer>
In the present invention, if the present pressure-sensitive adhesive sheet has a multilayer structure of two or more layers, it is preferable from the viewpoint of improving the storage stability, workability and adhesive properties of the present pressure-sensitive adhesive sheet. In such a case, layers other than the present pressure-sensitive adhesive layer As such, it is preferable to have an intermediate layer, and for example, the composition of the intermediate layer is arbitrary. However, from the viewpoint of further increasing interlayer adhesion, the pressure-sensitive adhesive composition that forms a layer other than the present pressure-sensitive adhesive layer preferably contains the (meth)acrylic polymer (A) as a main component resin. It is preferable to contain the same (meth)acrylic polymer (A) as the adhesive layer as the main component resin.
Furthermore, it is more preferable that layers other than the pressure-sensitive adhesive layer also contain a cross-linking agent (B) and a polymerization initiator (C). At that time, the cross-linking agent (B) more preferably contains a polyfunctional (meth)acrylate component (b-1) and a monofunctional (meth)acrylate component (b-2).

<How to make and use this adhesive sheet>
This pressure-sensitive adhesive sheet can also be used as a single pressure-sensitive adhesive sheet. For example, the pressure-sensitive adhesive composition may be directly applied to an adherend to form a sheet, the pressure-sensitive adhesive composition may be directly extruded, or the pressure-sensitive adhesive sheet may be injected into a mold to produce the pressure-sensitive adhesive sheet. can be done. Furthermore, the present pressure-sensitive adhesive sheet can also be produced by directly filling the present pressure-sensitive adhesive composition between members such as conductive members.

On the other hand, the present pressure-sensitive adhesive sheet can also be produced as a release film-attached pressure-sensitive adhesive sheet laminate comprising a pressure-sensitive adhesive layer formed from the present pressure-sensitive adhesive composition and a release film. For example, the present pressure-sensitive adhesive composition can be in the form of a release film-attached pressure-sensitive adhesive sheet formed by molding a single-layer or multilayer sheet on a release film.

Examples of materials for the release film include polyester film, polyolefin film, polycarbonate film, polystyrene film, acrylic film, triacetylcellulose film, and fluororesin film. Among these, polyester films and polyolefin films are particularly preferred.

The thickness of the release film is not particularly limited. Among them, for example, from the viewpoint of workability and handleability, the thickness is preferably 25 μm to 500 μm, more preferably 38 μm or more or 250 μm or less, and more preferably 50 μm or more or 200 μm or less.

<Main laminate>
A laminate for an image display device (referred to as "this laminate") according to an example of an embodiment of the present invention includes the pressure-sensitive adhesive sheet interposed between two constituent members for an image display device, and the two components for an image display device. It is a layered product for constituting an image display device having a structure in which the constituent members are laminated via the pressure-sensitive adhesive sheet.
By irradiating the adhesive sheet with an active energy ray, the laminate is cured (the adhesive sheet after curing is referred to as a “mainly cured adhesive sheet”), and two images are displayed. Device components can be laminated together.

At this time, the two image display device constituent members are any one or two of the group consisting of a touch sensor, an image display panel, a surface protection panel, a polarizing film and a retardation film. A laminated body made of a combination of the above can be mentioned.

When at least one of the two constituent members of the image display device has unevenness on the contact surface with the pressure-sensitive adhesive sheet, the ratio of depth (mm)/bottom area (mm ² ) is 1.0×10. ^-5 to 3.0×10 ^-1 , especially 5.0×10 ^-5 or more or 2.0×10 ^-1 or less, especially 1.0×10 ^-4 or more or 1.0×10 ^-1 or less If the adhesive sheet has a certain bottomed hole, the effect of the present pressure-sensitive adhesive sheet can be more enjoyed.
At this time, the pressure-sensitive adhesive composition of the present pressure-sensitive adhesive sheet can be filled into the bottomed holes, and at that time, the bottomed holes can be filled so that there are no voids having a diameter of at least 1 mm or more. . The "diameter of voids" means the longest diameter in the case of a non-spherical shape with voids.

Specific examples of the present laminate include, for example, release film/present adhesive sheet or post-curing adhesive sheet/touch panel, image display panel/present adhesive sheet or post-curing adhesive sheet/touch panel, image display panel/present adhesive sheet or Adhesive sheet after main curing/touch panel/adhesive sheet or adhesive sheet after main curing/protection panel, polarizing film/adhesive sheet or adhesive sheet after main curing/touch panel, polarizing film/adhesive sheet or adhesive sheet after main curing/touch panel / main pressure-sensitive adhesive sheet or post-hardening pressure-sensitive adhesive sheet/protective panel.

The touch panel includes a structure in which a touch panel function is inherent in a protective panel, and a structure in which an image display panel has a touch panel function inherently.
Therefore, the present laminate is, for example, release film / present adhesive sheet or post-curing pressure-sensitive adhesive sheet / protective panel, release film / present pressure-sensitive adhesive sheet or post-curing pressure-sensitive adhesive sheet / image display panel, image display panel / present pressure-sensitive adhesive sheet Alternatively, the adhesive sheet/protective panel may be used after the main curing.
In the above configuration, the conductive layer is provided between the present adhesive sheet or the post-curing adhesive sheet and a member such as a touch panel, surface protection panel, image display panel, polarizing film, or retardation film adjacent thereto. All intervening configurations can be mentioned. However, it is not limited to these lamination examples.

It should be noted that the touch panel may be of a resistive film type, a capacitive type, an electromagnetic induction type, or the like. Among them, the capacitive method is preferable.

Materials for the protective panel include glass, acrylic resin, polycarbonate resin, alicyclic polyolefin resin such as cycloolefin polymer, styrene resin, polyvinyl chloride resin, polyimide resin, phenol resin, Plastics such as melamine-based resins and epoxy-based resins may also be used.

The image display panel is composed of other optical films such as polarizing films and other retardation films, liquid crystal materials, and backlight systems (usually, the adhesive composition or adhesive article adheres to the image display panel with an optical film. There are STN method, VA method, IPS method, etc. depending on the control method of the liquid crystal material, and any method may be used.

The laminate can be used as a component of image display devices such as liquid crystal displays, organic EL displays, inorganic EL displays, electronic papers, plasma displays, and microelectromechanical system (MEMS) displays.

<Method for producing a laminate for constituting an image display device>
Next, an example of the manufacturing method of this laminated body is demonstrated. However, the method for manufacturing the laminate is not limited to the method described below.

The laminated body is formed by laminating the present pressure-sensitive adhesive sheet on one side of the first image display device constituent member to form a laminated body, and the second image display device constituent member on the lamination surface and the lamination surface thereof. , and the adhesive sheet of the above laminated body is faced and laminated to form a laminate.
As a lamination method, known methods such as roll lamination, press lamination using a parallel plate, and diaphragm lamination can be used.
As the lamination environment, there are an air lamination method in which lamination is performed under normal pressure and a vacuum lamination method in which lamination is performed under reduced pressure. From the viewpoint of preventing air bubbles during lamination, a method of laminating with a parallel plate under a reduced pressure environment is preferable.

Next, the laminated body is heated to hot-melt the pressure-sensitive adhesive sheet. That is, while heating the laminate to 40° C. or higher and 80° C. or lower to hot-melt the adhesive sheet, the adhesive composition is applied to the surface of the adherend, and the second image display device constituent member forms the uneven portion. If so, the pressure-sensitive adhesive composition is allowed to flow into the irregularities. The heating temperature at this time is preferably 40° C. or higher and 80° C. or lower, more preferably 45° C. or higher and 75° C. or lower, and more preferably 50° C. or higher and 70° C. or lower.
Moreover, a pressure treatment may be performed together with the heat treatment, and an air pressure of 0.2 MPa or more and 0.8 MPa or less may be applied to the laminate. At this time, the atmospheric pressure is preferably 0.2 MPa or more and 0.8 MPa or less, more preferably 0.25 MPa or more or 0.75 MPa or less, and more preferably 0.30 MPa or more or 0.70 MPa or less.
The treatment time is preferably 5 minutes or more, particularly 5 minutes or more or 60 minutes or less, and more preferably 10 minutes or more or 45 minutes or less.

Next, the present laminate can be produced by irradiating the present pressure-sensitive adhesive sheet sandwiched between the first and second image display constituent members with an active energy ray to cure the present pressure-sensitive adhesive sheet. can.
In the above, the second image display device constituent member may be a member having an uneven portion, for example, a hole with a bottom on the contact surface with the adhesive sheet. The pressure-sensitive adhesive composition can sufficiently flow into the bottomed holes of the component.

In the present invention, ultraviolet light and visible light are suitable as the active energy ray in the above active energy ray irradiation.
The light source for irradiating the active energy ray includes, for example, a high-pressure mercury lamp, a metal halide lamp, a xenon lamp, a halogen lamp, an LED lamp, a fluorescent lamp, and the like. can be used according to
Also, the irradiation time and irradiation means are not particularly limited, but for example, in the case of ultraviolet irradiation, the integrated amount of light at a wavelength of 365 nm is preferably 100 mJ/cm ² to 10000 mJ/cm ² , more preferably 500 mJ/cm ² . 8000 mJ/cm 2 to 8000 mJ/cm ² , more preferably 1000 mJ/cm ² to 6000 mJ/cm ² , particularly preferably 1500 mJ/cm ² to 4000 mJ/cm ² .

As a preferred example of the present laminate, two image display device constituent members have a creep strain of 10% or more after 180 seconds at 80° C. at a thickness of 0.8 to 1.5 mm after curing under predetermined curing conditions. A layered product for image display device structure having a structure in which the cured adhesive sheet is interposed is also included. The post-curing pressure-sensitive adhesive sheet is a sheet after the present pressure-sensitive adhesive sheet has been photocured.
At this time, at least ^one of the constituent members of the image display device has ^unevenness . Those having bottomed pores of 3.0×10 ⁻¹ can be mentioned. In this case, it is preferable that the post-curing pressure-sensitive adhesive sheet is filled in the bottomed holes and filled in such a state that at least voids having a diameter of 1 mm or more are not present in the bottomed holes.
The "diameter of voids" means the longest diameter in the case of a non-spherical shape with voids.

<This image display device>
An image display device according to an example of an embodiment of the present invention (also referred to as "the present image display device") is an image display device including the laminate for forming the present image display device.
Specific examples of the image display device include a liquid crystal display, an organic EL display, an inorganic EL display, electronic paper, a plasma display, and a microelectromechanical system (MEMS) display.

<Explanation of terms>
In the present invention, when expressing “X to Y” (X and Y are arbitrary numbers), unless otherwise specified, “X or more and Y or less” and “preferably larger than X” or “preferably larger than Y” It also includes the meaning of "small".
In addition, when expressed as “X or more” (X is an arbitrary number) or “Y or less” (Y is an arbitrary number), it is also possible to express “preferably larger than X” or “preferably less than Y”. It also includes intent.
In the present invention, the term "sheet" conceptually includes sheets, films, and tapes.

The present invention is further illustrated by the following examples. However, the present invention is not limited to the examples shown below.

First, the details of the raw materials of the pressure-sensitive adhesive composition prepared in Examples will be described.

<(Meth) acrylic polymer (A)>
- (Meth) acrylic polymer (A-1): 6 parts by mass of polymethyl methacrylate macromonomer (Tg 105 ° C.) having a number average molecular weight of 2800, 74 parts by mass of butyl acrylate (Tg -55 ° C.), and 2-hydroxy Acrylic graft copolymer obtained by random copolymerization with 20 parts by mass of ethyl acrylate (Tg-15°C) (mass average molecular weight: 330,000, Tg-42°C)
- (Meth)acrylic polymer (A-2): 15 parts by mass of polymethyl methacrylate macromonomer (Tg 105°C) having a number average molecular weight of 2800, 81 parts by mass of butyl acrylate (Tg -50°C), and acrylic acid ( Tg 106° C.) 4 parts by mass of acrylic graft copolymer (mass average molecular weight: 160,000, Tg −36° C.)

The glass transition temperature of each copolymer component in the (meth)acrylic polymer is the literature value of the glass transition temperature obtained from the homopolymer of the component. Regarding the macromonomer, the literature value of the glass transition temperature obtained from the homopolymer of the component forming the high-molecular-weight skeleton in the macromonomer is described.
As for the glass transition temperature of the acrylic copolymer, the theoretical Tg calculated by the Fox calculation formula is described from the glass transition temperature and the composition ratio of each component of the copolymer.

<Crosslinking agent (B)>
Cross-linking agent (B-1): tricyclodecanedimethanol dimethacrylate Cross-linking agent (B-2): propoxylated pentaerythritol triacrylate

<Polymerization initiator (C)>
- Initiator (C-1): a mixture of 2,4,6-trimethylbenzophenone and 4-methylbenzophenone ("Esacure TZT" manufactured by IGM)

[Example 1]
(Meth)acrylic polymer (A-1) 100 parts by mass, crosslinking agent (B-1) 5 parts by mass, and initiator (C-1) 1.5 parts by mass are uniformly mixed to prepare an adhesive composition. did.
On a 100 μm-thick release film (PET film manufactured by Mitsubishi Chemical Co., Ltd.) subjected to silicone release treatment, the pressure-sensitive adhesive composition was spread in a sheet form to a thickness of 100 μm.

Next, on the sheet-like adhesive composition, a release film (PET film manufactured by Mitsubishi Chemical Corporation) having a thickness of 75 μm that has been subjected to silicone release treatment is laminated to form a laminate, and the release film/adhesive A release film-attached pressure-sensitive adhesive sheet 1 consisting of sheet 1/release film was obtained.
In addition, the adhesive sheet 1 was an active energy ray-curable adhesive sheet having an active energy ray-curable adhesive sheet that is cured by irradiation with an active energy ray.

[Examples 2-5, Comparative Examples 1-2]
Adhesive sheets 2 to 7 were produced in the same manner as in Example 1, except that the composition shown in Table 1 was changed.

[Comparative Example 3]
According to the formulation shown in Table 2, the (meth)acrylic polymer (A), the cross-linking agent (B), and the initiator (C) are uniformly mixed to obtain a pressure-sensitive adhesive composition, followed by silicone release treatment. On a 100 μm thick release film (Mitsubishi Chemical Co., Ltd. PET film), the pressure-sensitive adhesive composition was spread into a sheet so that the thickness would be 100 μm.
Next, on the sheet-like adhesive composition, a release film (PET film manufactured by Mitsubishi Chemical Corporation) having a thickness of 75 μm that has been subjected to silicone release treatment is laminated to form a laminate, and the release film/adhesive An intermediate layer pressure-sensitive adhesive sheet α1 with a release film was obtained, which consisted of sheet α1/release film (thickness: 100 μm).
Further, in the same manner as above, release film/adhesive sheet β1/release film-attached surface layer pressure-sensitive adhesive sheet β1 (thickness: 25 μm), release film/adhesive sheet β′1/release film A backing pressure-sensitive adhesive sheet β′1 (thickness: 25 μm) with a release film was obtained.
The release films on both sides of the pressure-sensitive adhesive sheet α1 with a release film are sequentially peeled off, and the release films of the surface layer pressure-sensitive adhesive sheet β1 with a release film and the back layer pressure-sensitive adhesive sheet β′1 with a release film are sequentially peeled off. Then, the front layer adhesive sheet β1 and the back layer adhesive sheet β'1 are sequentially laminated on the front and back surfaces of the adhesive sheet α1, and a 150 μm thick sheet consisting of (β1)/(α1)/(β'1) is formed. A release film-attached pressure-sensitive adhesive sheet 8 comprising a release film/adhesive sheet 8/release film having the pressure-sensitive adhesive sheet 8 was obtained.
In addition, the adhesive sheet 8 was an active energy ray-curable adhesive sheet having an active energy ray-curable adhesive sheet that is cured by irradiation with an active energy ray.

[Measurement and evaluation of physical properties]
The adhesive sheets 1 to 8 produced in Examples and Comparative Examples were subjected to the following various measurements and evaluations. The evaluation results are summarized in Tables 1 and 2.

<Creep test>
Using a plurality of each of the adhesive sheets prepared in Examples and Comparative Examples, after laminating the adhesive sheet with the release film removed so that the thickness is about 0.9 mm, the release film/thickness about 0 A pressure-sensitive adhesive sheet with a release film was prepared by stacking the pressure-sensitive adhesive sheet/release film to a thickness of 9 mm, and punched out into a circle having a diameter of 8 mm with a punching machine.
Using a rheometer ("DHR-2" manufactured by TA Instruments), measuring jig: diameter 8 mm parallel plate, temperature: 50 ° C., pressure: 1000 Pa, strain (%) after applying for 1200 seconds is measured. did.

<Creep test (after curing)>
For the pressure-sensitive adhesive sheets with release films prepared in Examples and Comparative Examples, using a high-pressure mercury lamp, the pressure-sensitive adhesive sheet was peeled through a polyethylene terephthalate film so that the integrated light amount at 365 nm was 4000 mJ / cm ² . The adhesive sheet was cured by irradiating with ultraviolet rays.
The cured pressure-sensitive adhesive sheets were laminated to a thickness of about 0.9 mm and punched out into a circle with a diameter of 8 mm.
Using a rheometer ("DHR-2" manufactured by TA Instruments), measuring jig: diameter 8 mm parallel plate, temperature: 80 ° C., pressure: 1000 Pa, strain (%) after applying for 180 seconds is measured. did.

<Gel fraction>
About 0.1 g of adhesive sheet pieces were collected from each of the adhesive sheets prepared in Examples and Comparative Examples.
The collected adhesive sheet piece was wrapped in a bag-shaped SUS mesh (#150) having a mass (X), and the mouth of the bag was closed to prepare a sample, and the mass (Y) of the sample was measured. After the sample was immersed in ethyl acetate and stored in the dark at 23°C for 24 hours, the sample was taken out and heated at 70°C for 4.5 hours to evaporate the ethyl acetate. (Z) was measured. The gel fraction was calculated from the measured masses according to the following formula.
Gel fraction (%) = [(Z - X) / (Y - X)] x 100

The pressure-sensitive adhesive sheets with release films prepared in Examples and Comparative Examples were irradiated with ultraviolet light through the release films using a high-pressure mercury lamp so that the integrated light intensity at 365 nm was 4000 mJ/cm ² . and cured the adhesive sheet.
For the adhesive sheet after curing, the gel fraction after curing with active energy rays was obtained in the same manner as the gel fraction evaluation procedure described above.

<Adhesive strength>
The release film on one side of the pressure-sensitive adhesive sheets prepared in Examples and Comparative Examples was peeled off, and a polyethylene terephthalate film having a thickness of 100 μm ("Cosmoshine A4300" manufactured by Toyobo Co., Ltd.) was laminated as a backing film to prepare a laminate.
After cutting the laminate to a length of 150 mm and a width of 10 mm, the adhesive surface exposed by peeling off the remaining release film was roll-bonded to the adhesive sheet by reciprocating the roll once on soda lime glass, and the temperature was 60 ° C. After curing for 30 minutes, it was finished and adhered.
The adhesive force measurement sample was peeled off at a peel angle of 180° and a peel speed of 60 mm/min in an environment of 23°C and 40% RH, and the peel force (N/cm) to glass was measured.

<Adhesive strength (after curing)>
One of the release films of the pressure-sensitive adhesive sheets with release films prepared in Examples and Comparative Examples was peeled off, and a polyethylene terephthalate film having a thickness of 100 μm (“Cosmoshine A4300” manufactured by Toyobo Co., Ltd.) was laminated as a backing film to obtain a laminate. Got ready.
After the laminate was cut to a length of 150 mm and a width of 10 mm, the remaining release film was peeled off, and the exposed adhesive surface was roll-bonded to the soda-lime glass by reciprocating the roll once. After curing the laminated product for 30 minutes at a temperature of 60 ° C. and finishing it, the adhesive sheet was cured by irradiating ultraviolet rays at 365 nm through the backing film so that the integrated light amount was 4000 mJ / cm ² , and 15 minutes at 23 ° C. After curing for a period of time, a sample for adhesive strength measurement was obtained.
This adhesive force measurement sample was peeled off at a peel angle of 180 ° and a peel speed of 60 mm / min in an environment of 23 ° C. and 40% RH, and the peel force (N / cm) to the glass was measured. I asked for stickiness.

<Oil resistance>
The pressure-sensitive adhesive sheets with release films prepared in Examples and Comparative Examples were cut into 10 mm x 10 mm squares, and one release film was peeled off to expose the surface of the pressure-sensitive adhesive sheet to obtain a fat swelling ratio measurement sample.
The fat swelling rate measurement sample was immersed in an artificial sebum solution (oleic acid:squalene=1:1) in an environment of 25° C. for 4 days. The area of the fat swelling rate measurement sample before being immersed in the artificial sebum liquid is So, the area of the fat swelling rate measurement sample after immersion in the artificial sebum liquid is St, and the fat swelling rate was obtained from the following formula (i).
Oil swelling rate (%) = [(St-So) / So] × 100 (i)

<Hot meltability>
On one side of a 50 μm thick polyethylene terephthalate film (manufactured by Mitsubishi Chemical Co., Ltd. “S-100, thickness 50 μm”), a 20 μm thick double-sided adhesive sheet was laminated with a hand roll, and a polyethylene terephthalate film with an adhesive layer (total thickness of 120 μm) was laminated. made. The adhesive layer-attached polyethylene terephthalate film was cut into a size of 54 mm×82 mm, and bottomed holes with a diameter of 4 mm were formed at the four corners of the cut film so that the distance from the end face to the center of the hole was 6 mm.
The film was roll-bonded to soda-lime glass of 54 mm×82 mm and thickness of 0.55 mm to prepare a base material for hole-filling evaluation having four bottomed holes with a diameter of 4 mm and a depth of 120 μm.

The adhesive surface exposed by peeling off one of the release films of the adhesive sheets with release films prepared in Examples and Comparative Examples was roll-pressed to soda lime glass (82 mm x 54 mm x 0.55 mm thick). Next, the remaining release film is peeled off, and the exposed adhesive surface and the surface having bottomed holes of the substrate for evaluation of hole-filling property are opposed to each other, and are subjected to reduced pressure (absolute pressure of 2 kPa) using a vacuum laminator. was pressed and laminated. Heat and pressure treatment was performed using an autoclave (65° C., gauge pressure 0.45 MPa, 20 minutes) to prepare a laminate for hot-melt property evaluation.

The laminate was visually observed, and the case where a void having a diameter of 1 mm or more was found inside one or more bottomed holes was evaluated as "poor", and the other was evaluated as "good".
The diameter of the voids was determined as the longest diameter when the voids were non-spherical.

<Storability>
One of the release films of the adhesive sheets with release films prepared in Examples and Comparative Examples was peeled off, the adhesive sheet was cut into 30 mm × 30 mm squares, and a release film was superimposed on the release film. On the other hand, a notch mark of the size of the pressure-sensitive adhesive sheet (30 mm×30 mm square) was cut (half-cut). In that state, it was stored in an environment of 40° C. for 200 hours. For each side of the pressure-sensitive adhesive sheet, the maximum value of the portion of the paste protruding from the marked line was measured, and the average value of the four sides was taken as the paste protruding distance (mm).
When the paste protruding distance was less than 0.3 mm, it was judged as "good", and when it was 0.3 mm or more, it was judged as "poor".

<Durability>
The adhesive surface of a polarizing plate with an adhesive layer (70 mm × 150 mm) with a thickness of 87 μm is roll-bonded to soda lime glass with a thickness of 75 mm × 155 mm and a thickness of 0.55 mm, and durability evaluation consisting of a polarizing plate with an adhesive layer / soda lime glass. A base material for

One of the release films of the pressure-sensitive adhesive sheets with release films prepared in Examples and Comparative Examples was peeled off, and the exposed pressure-sensitive adhesive surface was roll-pressed to soda-lime glass (75 mm×155 mm×0.55 mm thick). Next, the remaining release film is peeled off, and the exposed adhesive surface and the polarizing plate surface of the substrate for durability evaluation are opposed to each other, and press-bonded under reduced pressure (absolute pressure 2 kPa) using a vacuum bonding machine. combined.
After applying heat and pressure treatment (65 ° C., gauge pressure 0.45 MPa, 20 minutes) using an autoclave, ultraviolet rays at 365 nm are irradiated through soda lime glass so that the integrated light amount is 4000 mJ / cm ² to adhere. The sheet was cured to prepare a sample for durability evaluation.

This reliability evaluation sample is put into a heat cycle tester, and 100 cycles are performed at high temperature and low temperature cycles (high temperature: 80 ° C., low temperature: -40 ° C., exposure time: 30 minutes at each temperature, temperature change rate: within 5 minutes). I went and saved it.

The sample for reliability evaluation after storage was visually observed, and if no glue extrusion on the edge surface and no air bubbles were observed on the surface, it was judged as "Good", and the adhesive extrusion on the edge and/or air bubbles on the surface were judged to be "Good". The one in which was observed was judged as "x (poor)".

The pressure-sensitive adhesive sheets of Examples had creep properties and oil swelling ratios within predetermined ranges, and were excellent in hot-melt properties, oil resistance, storage stability and durability.
The adhesive sheets of Examples 1 to 4 contained a cross-linking agent, and the creep strain after curing at 80°C for 180 seconds was 80% or less. As compared with the pressure-sensitive adhesive sheet of Example 5, which was not coated with the adhesive, the durability in high-temperature and low-temperature environments was much better.
On the other hand, the pressure-sensitive adhesive sheet 6 of Comparative Example 1 had a high fat expansion coefficient and poor oil resistance. In addition, the creep strain amount after 1200 seconds at 50° C. was large, and the storability was poor.
The pressure-sensitive adhesive sheet 7 of Comparative Example 2 had a high fat expansion coefficient and poor oil resistance. In addition, the creep strain amount after 1200 seconds at 50° C. was small, and the hot-melt properties were insufficient.
The pressure-sensitive adhesive sheet 8 of Comparative Example 3 had a satisfactory creep strain amount after 1200 seconds at 50°C, but had a high fat expansion coefficient and poor oil resistance.
From the above, it can be seen that it is difficult to achieve both oil resistance, fluidity, and hot-melt properties.

Claims (18)

1. An active energy ray-curable pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer containing a (meth)acrylic polymer (A) and satisfying the following requirements (1) and (2).
   (1) The thickness is 0.8 to 1.5 mm, and the strain (creep strain) after applying a pressure of 1000 Pa at a temperature of 50° C. for 1200 seconds is 150% or more and 1500% or less.
   (2) Let So be the initial area of the adhesive sheet, and St be the area after immersing the adhesive sheet in artificial sebum solution (squalene:oleic acid = 1:1 mixture) at 25°C for 4 days. The fat and oil swelling ratio determined by the formula (i) is 30% or less.
   Oil swelling rate (%) = [(St-So) / So] × 100 (i)
2. The active energy ray-curable pressure-sensitive adhesive sheet according to claim 1, wherein the (meth)acrylic polymer (A) is a block copolymer and/or a graft copolymer.
3. The (meth)acrylic polymer (A) is a copolymer containing structural units derived from a macromonomer, and the copolymerization ratio of the macromonomer is 3 to 10 parts by mass with respect to 100 parts by mass of the polymer (A). The active energy ray-curable pressure-sensitive adhesive sheet according to claim 2, which is a part.
4. The (meth)acrylic polymer (A) has, as monomer components, an alkyl (meth)acrylate having an alkyl group having 6 or less carbon atoms and a vinyl monomer having a polar group, and the acrylic polymer (A The content of alkyl (meth)acrylate having 6 or less carbon atoms in the alkyl group in the monomer component forming ) is 40% by mass or more, and the content of vinyl monomer having a polar group is 10% by mass or more and 50% by mass. The active energy ray-curable pressure-sensitive adhesive sheet according to any one of claims 1 to 3, wherein:
5. Claims 1 to 4, wherein the pressure-sensitive adhesive layer is a layer formed from a pressure-sensitive adhesive composition containing a (meth)acrylic polymer (A), a cross-linking agent (B) and/or a polymerization initiator (C). The active energy ray-curable pressure-sensitive adhesive sheet according to any one of .
6. The active energy ray-curable pressure-sensitive adhesive sheet according to claim 5, wherein the cross-linking agent (B) is a polyfunctional (meth)acrylate (b-1) having a cyclic structure.
7. 5. The content of the polyfunctional (meth)acrylate (b-1) is 0.5 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the (meth)acrylic polymer (A). Or the active energy ray-curable pressure-sensitive adhesive sheet according to 6.
8. The active energy ray-curable pressure-sensitive adhesive sheet according to any one of claims 1 to 7, which has a gel fraction of 0% or more and 20% or less.
9. Claims ¹ to 8, wherein when curing is performed by irradiating an active energy ray with a wavelength of 365 nm at an integrated light amount of 4000 mJ/c2, the gel fraction increases compared to before curing, and the gel fraction becomes 10% or more and 80% or less. The active energy ray-curable pressure-sensitive adhesive sheet according to any one of .
10. The strain ⁽ creep strain ) is 5% or more and 80% or less, the active energy ray-curable adhesive sheet according to any one of claims 1 to 9.
11. A release film-attached pressure-sensitive adhesive sheet laminate having a configuration in which the active energy ray-curable pressure-sensitive adhesive sheet according to any one of claims 1 to 10 and a release film are laminated.
12. A pressure-sensitive adhesive sheet obtained by curing the active energy ray-curable pressure-sensitive adhesive sheet according to any one of claims 1 to 10.
13. A lamination for image display device construction, wherein two image display device constituent members are laminated via an active energy ray-curable pressure-sensitive adhesive sheet having a fat swelling rate of 30% or less determined by the following formula (i): being a body,
    The pressure-sensitive adhesive sheet comprises a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive resin composition containing a (meth)acrylic polymer (A), and has a thickness of 0.8 to 1.5 mm and a temperature of 50 ° C. A laminate for constituting an image display device, having a strain (creep strain) of 150% or more and 1500% or less after applying a pressure of 1000 Pa for 1200 seconds.
    Oil swelling rate (%) = [(St-So) / So] × 100 (i)
    In formula (i), So is the initial area of the adhesive sheet, and St is the area after immersing the adhesive sheet in an artificial sebum solution (squalene:oleic acid = 1:1 mixture) at 25 ° C. for 4 days. be.
14. A configuration in which two image display device constituent members are laminated via a post-curing adhesive sheet obtained by curing an active energy ray-curable adhesive sheet having a fat swelling ratio of 30% or less as determined by the following formula (i). A laminate for configuring an image display device comprising
    The pressure-sensitive adhesive sheet has a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive composition containing a (meth)acrylic polymer (A), and has a thickness of 0.8 to 1.5 mm, a temperature of 80 ° C., and a temperature of 1000 Pa. A laminate for constituting an image display device, having a strain (creep strain) of 5% or more and 220% or less after applying a pressure of 180 seconds.
    Oil swelling rate (%) = [(St-So) / So] × 100 (i)
    In formula (i), So is the initial area of the adhesive sheet, and St is the area after immersing the adhesive sheet in an artificial sebum solution (squalene:oleic acid = 1:1 mixture) at 25 ° C. for 4 days. be.
15. The laminate for constituting an image display device according to claim 13 or 14, wherein the pressure-sensitive adhesive sheet has a multi-layer structure of two or more layers.
16. At least one of the constituent members of the image display device has a depth (mm)/bottom area (mm ² ) of 1.0×10 ⁻⁵ to 3.0×10 ⁻¹ on the contact surface with the pressure-sensitive adhesive sheet. 16. The layered product for constituting an image display device according to any one of claims 13 to 15, having bottomed holes.
17. The image display device constituent member is a laminate composed of any one or a combination of two or more of the group consisting of a touch panel, an image display panel, a surface protection panel, a polarizing film and a retardation film. 17. The laminate for constituting an image display device according to any one of 16.
18. An image display device constructed using the laminate for image display device construction according to any one of claims 13 to 17.