TWI820299B - Adhesive sheet, adhesive sheet with peelable sheet, laminated body, and method of manufacturing the laminated body - Google Patents

Abstract

The present invention provides an adhesive sheet that can exhibit excellent substrate adhesion and durability even under high temperature and high humidity conditions, and has excellent processability. Specifically, the present invention is an adhesive sheet having an adhesive layer in which an adhesive composition is in a semi-hardened state. The adhesive composition contains a cross-linked acrylic copolymer A having an acid component and a cross-linking agent. B. Multifunctional monomer C with more than 2 reactive double bonds in the molecule, monofunctional monomer D with 1 reactive double bond in the molecule and photopolymerization initiator E, and the aforementioned cross-linked acrylic copolymer The glass transition temperature (Tg) of A is -40°C or above, and the adhesive layer has post-hardening properties. When the adhesive layer is irradiated with active energy rays in such a way that the accumulated light intensity is 3000mJ/ ^cm2 and then hardened, the adhesive layer will The layer satisfies the following physical properties (1) and (2); Physical properties (1): The elongation at break measured in a tensile test with a tensile speed of 10mm/min is less than 500%; Physical properties (2): Measured using the following measurement conditions The peeling distance of each load under i) 85℃, relative humidity 85% and ii) 85℃, relative humidity less than 10% is less than 50mm: (Measurement conditions) The adhesive surface of the adhesive layer with a width of 25mm and a length of 100mm is The area with a medium width of 25mm and a length of 75mm is adhered to the adherend and then hardened; in each environment of i) 85℃, relative humidity 85% and ii) 85℃, relative humidity less than 10%, the adhesive layer Fix the adherend in the horizontal direction in such a way that the non-fitting area hangs downward; apply a load of 100g on the lengthwise end of the non-fitting area of the adhesive layer for 5 minutes, and measure the length of the adhesive layer's fitting area. The peeling distance of the adherend is defined as the peeling distance under a certain load at i) 85°C and relative humidity of 85% and ii) 85°C and relative humidity of less than 10%.

Description

Adhesive sheet, adhesive sheet with peelable sheet, laminated body, and method of manufacturing the laminated body

Field of invention

The present invention relates to an adhesive sheet, an adhesive sheet with a release sheet, a laminated body, and a method for manufacturing the laminated body.

Background technology

Conventionally, display devices such as liquid crystal displays (LCDs) and input devices such as touch panels used in combination with the display devices have been widely used. In the manufacture of these display devices and input devices, transparent adhesive sheets are used for bonding optical components, and transparent adhesive sheets are also used for bonding display devices and input devices.

The adhesive composition forming the adhesive sheet for optical members can be produced using a known polymerization method. Examples of this polymerization method include solution polymerization, block polymerization, suspension polymerization, and emulsion polymerization. Among them, solvent-based adhesives are widely used in the adhesive layer because they are easy to produce and can produce an optically transparent adhesive sheet. adhesive sheet. Examples of solvent-based adhesives include those containing acrylic resin as a main component. Such an acrylic resin can be obtained by performing a polymerization reaction in a solvent in which an acrylic monomer has been dissolved using a method called solution polymerization. In solution polymerization, as the polymerization proceeds, the molecular weight of the polymer will increase, and the viscosity of the reaction solution will increase. Therefore, there are technical limitations in the synthesis of polymers with the necessary molecular weight in order to obtain the cohesive force necessary for use as an adhesive. Therefore, in order to ensure the necessary cohesive force of the adhesive, a cross-linking agent that can react with the acrylic resin, such as an isocyanate compound or an epoxide compound, is blended into the adhesive composition. This cross-linking agent reacts with the acrylic resin over time to build a cross-linked network and improve the cohesion of the adhesive layer.

In addition, as a method of forming an adhesive sheet for optical members, a method of curing by two-stage curing is sometimes used. In this two-stage curing, cross-linking using heat (or active energy rays) and then using active energy rays is sometimes used. The aggregation of energy rays (or heat). Such an adhesive sheet is formed, for example, from an adhesive composition having both thermosetting properties and active energy ray curing properties (hereinafter also referred to as a "double-curing adhesive composition"). Therefore, it has both thermosetting properties and active energy ray curing properties. Sclerosis. Therefore, before bonding to the adherend, for example, it is only thermally hardened to develop a hardness that is easy to handle. Then, after bonding to the adherend, it is hardened using active energy rays (called post-hardening). Hardening or post-curing), whereby it can be firmly adhered to the adherend.

For example, Patent Document 1 describes an adhesive sheet that contains an adhesive layer formed by semi-hardening an adhesive composition by heating, and the adhesive composition contains: a base polymer (A ), which contains a non-crosslinked (meth)acrylate unit (a1) and an acrylic monomer unit (a2) with a crosslinkable functional group; monomer (B), which contains lauryl acrylate (b1); Cross-linking agent (C), which reacts with the base polymer (A) by heat; polymerization initiator (D), which starts the polymerization reaction of the monomer (B) by irradiation of active energy rays; and solvent ( E). Furthermore, Patent Document 2 discloses an adhesive sheet having at least one ultraviolet curable adhesive layer. Here, the storage elastic modulus G' (1Hz) of the adhesive layer after ultraviolet curing at a measurement temperature of 20°C and a frequency of 1Hz is 1×10 ⁴ to 1×10 ⁶ Pa. Prior art documents Patent documents

Patent Document 1: Japanese Patent Application Publication No. 2016-084391 Patent Document 2: Japanese Patent Application Publication No. 2012-031059

Summary of the invention The problem to be solved by the invention

However, when the inventors studied the characteristics of the adhesive sheets described in Patent Documents 1 and 2, they found that the adhesion to the substrate and the durability were insufficient, especially under high-temperature and high-humidity conditions. Obtain substrate adhesion and durability. In addition, the workability after hardening is also insufficient, and there is still room for improvement.

Therefore, in order to solve the problems of this conventional technology, the inventors conducted research for the purpose of providing an adhesive sheet that can exhibit excellent substrate adhesion and durability even under high temperature and high humidity conditions. , and has excellent processability. means to solve problems

In order to achieve the above-mentioned subject, the inventors have repeatedly and carefully studied and found that the above-mentioned object can be achieved through the following adhesive sheet, and thus completed the present invention, namely: an adhesive sheet that has the adhesive composition in a semi-hardened state. The adhesive layer, and the aforementioned adhesive composition contains a specific cross-linkable acrylic copolymer with an acid component A, a cross-linking agent B, a multi-functional monomer C with more than two reactive double bonds in the molecule, and Monofunctional monomer D with one reactive double bond and photopolymerization initiator E satisfy specific physical property groups at the same time.

That is, the present invention relates to the following adhesive sheet, an adhesive sheet with a release sheet, a laminated body, and a method for manufacturing the laminated body. 1. An adhesive sheet having an adhesive layer in which an adhesive composition is in a semi-hardened state. The adhesive composition contains a cross-linked acrylic copolymer A having an acid component, a cross-linking agent B, and a Multifunctional monomer C with two or more reactive double bonds, monofunctional monomer D with one reactive double bond in the molecule and photopolymerization initiator E, and the glass transition temperature of the aforementioned cross-linked acrylic copolymer A (Tg) is -40°C or above, and the adhesive layer has post-hardening properties. When the adhesive layer is irradiated with active energy rays at a cumulative light intensity of 3000mJ/ ^cm2 and then hardened, the adhesive layer satisfies the following physical properties: (1) and (2); Physical properties (1): The elongation at break measured in a tensile test with a tensile speed of 10mm/min is less than 500%; Physical properties (2): Measured at i) 85°C using the following measurement conditions , relative humidity 85% and ii) 85℃, relative humidity less than 10%, the peeling distance of each load is less than 50mm: (Measurement conditions) The adhesive surface of the adhesive layer with a width of 25mm and a length of 100mm has a width of 25mm and a length of The 75mm area is attached to the adherend and then hardened. Under each environment of i) 85℃, relative humidity 85% and ii) 85℃, relative humidity less than 10%, fix the adherend in the horizontal direction by hanging the non-adhesive area of the adhesive layer downward. Apply a load of 100g to the length-direction end of the non-laminated area of the adhesive layer for 5 minutes, and measure the peeling distance of the adhesive layer's bonded area from the adherend during the period, as i) 85°C, relative humidity 85% and ii) Peeling distance of each load under 85℃ and relative humidity less than 10%. 2. The adhesive sheet as described in item 1 above, wherein the content of the monofunctional monomer D is 10 to 40 parts by mass relative to 100 parts by mass of the crosslinkable acrylic copolymer A. 3. The adhesive sheet of item 1 or 2 above, wherein the content of the polyfunctional monomer C is 10 to 40 parts by mass relative to 100 parts by mass of the crosslinkable acrylic copolymer A. 4. The adhesive sheet according to any one of the above items 1 to 3, wherein the acid value of the cross-linked acrylic copolymer A is 1 mgKOH/g or more. 5. The adhesive sheet according to any one of the above items 1 to 4, wherein the difference between the gel fraction of the adhesive layer in the semi-hardened state and the gel fraction after post-hardening is more than 15%. 6. An adhesive sheet with a release sheet, which has a pair of release sheets with mutually different release forces on both sides of the adhesive sheet according to any one of the above items 1 to 5. 7. A laminated body comprising the adhesive sheet according to any one of items 1 to 5 above and an adherend provided on at least one side of the adhesive sheet, wherein the adhesive layer of the adhesive sheet is formed by irradiation of active energy The line then hardens. 8. A method for manufacturing a laminated body, which sequentially includes: step 1, layering the adhered volume on at least one side of the adhesive sheet as in any one of the above items 1 to 5; and step 2, by adhering the aforementioned The adhesive layer of the sheet is irradiated with active energy rays to harden the adhesive layer. Invention effect

According to the present invention, an adhesive sheet can be produced that exhibits excellent substrate adhesion and durability even under high temperature and high humidity conditions, and has excellent processability.

Form used to implement the invention

Hereinafter, the present invention will be described in detail. The description of the constituent elements described below may be based on representative embodiments or specific examples, and the present invention is not limited to such embodiments. In addition, in this specification, the numerical range represented by "~" means a range including the numerical values described before and after "~" as the lower limit and the upper limit.

In addition, in this specification, "(meth)acrylate" means both or any one of acrylate and methacrylate, and "(meth)acrylic acid" means both or any one of acrylic acid and methacrylic acid. In addition, in this specification, "monomer" and "monopolymer" are synonymous, and "polymer" and "polymer" are synonymous.

<Adhesive sheet> The adhesive sheet of the present invention has an adhesive layer in which the adhesive composition is in a semi-hardened state. The adhesive composition contains a cross-linked acrylic copolymer A containing an acid component, a cross-linking agent B, a multifunctional monomer C having two or more reactive double bonds in the molecule, and a polyfunctional monomer C having one reactive double bond in the molecule. Monofunctional monomer D and photopolymerization initiator E, and the glass transition temperature (Tg) of the aforementioned cross-linked acrylic copolymer A is -40°C or above, the aforementioned adhesive layer has post-hardening properties, when the accumulated light amount constitutes 3000mJ When ^the adhesive layer is irradiated with active energy rays and then hardened using a method of The elongation at break in is less than 500%; Physical properties (2): The peeling distance under a certain load measured using the following measurement conditions: i) 85°C, relative humidity 85% and ii) 85°C, relative humidity less than 10%: Below 50mm: (Measurement conditions) The area of 25mm in width and 75mm in length on the adhesive surface of the adhesive layer with a width of 25mm and a length of 100mm is attached to the adherend and allowed to harden. Under each environment of i) 85℃, relative humidity 85% and ii) 85℃, relative humidity less than 10%, fix the adherend in the horizontal direction by hanging the non-adhesive area of the adhesive layer downward. Apply a load of 100g to the length-direction end of the non-laminated area of the adhesive layer for 5 minutes, and measure the peeling distance of the adhesive layer's bonded area from the adherend during the period, as i) 85°C, relative humidity 85% and ii) Peeling distance of each load under 85℃ and relative humidity less than 10%. In addition, the peeling distance under a constant load under the condition i) shows the adhesion to the high-temperature and high-humidity substrate, and the peeling distance under a constant load under the condition ii) shows the adhesion to the high-temperature substrate.

The adhesive sheet of the present invention having the above structure can exhibit excellent substrate adhesion and durability even under high temperature and high humidity conditions, and is also excellent in processability. This effect of the present invention can be obtained especially when the cross-linked acrylic copolymer A contained in the adhesive composition has an acid component and the glass transition temperature (Tg) is -40°C or higher, and satisfies the above requirements. Conditions for physical properties (1) and (2). In particular, we believe that by having an acid component in the cross-linked acrylic copolymer A, the uniformity of the cross-linked structure formed by the cross-linked acrylic copolymer A is improved, thereby improving the durability of the adhesive sheet. Furthermore, we believe that by adding an acid component to the crosslinkable acrylic copolymer A, the adhesion (substrate adhesion) between the adhesive sheet and the adherend is improved, thereby also improving the durability of the adhesive sheet. sex. Furthermore, by satisfying the above physical property (1) conditions, the adhesive layer after post-hardening has an appropriate hardness and has excellent workability.

In this specification, the durability of the adhesive sheet can be evaluated using the following method. First, a cellulose triacetate film is attached to one side of the adhesive sheet, and a polycarbonate plate is attached to the other side. The accumulated light intensity is 3000mJ/ ^cm2 , and the cellulose triacetate film is irradiated from the side. Active energy rays harden the adhesive layer. Then, the adhesive sheet was left to stand for 240 hours respectively at i) 85°C and a relative humidity of 85% and ii) 85°C and a relative humidity of less than 10%. Then, the adhesive sheet is observed, and when the adhesive sheet can be prevented from floating or peeling off from the polycarbonate plate and/or the cellulose triacetate film, the durability is judged to be excellent. In addition, the judgment of i) condition shows high temperature and high humidity durability, and the judgment of ii) condition shows high temperature durability.

In addition, the adhesive sheet of the present invention can suppress stickiness of the end surface after post-hardening, for example, it can prevent the adhesive from adhering to the punching knife during punching, or the accompanying deformation of the adhesive layer. Furthermore, after the adhesive sheet of the present invention is post-hardened and punched into the desired size, when it is cut for the purpose of adjusting the end face, the adhesive layer will not deform, ooze, or peel off, and the processing will not occur. Performance is also excellent.

＜Structure of adhesive sheet＞ The adhesive sheet of the present invention has an adhesive layer. The adhesive sheet may be a single layer adhesive sheet consisting only of the adhesive layer. Moreover, the adhesive sheet may be a single-sided adhesive sheet provided with a base material (preferably a transparent base material) on one side, or may be a double-sided adhesive sheet. Examples of adhesive sheets include: a single-layer adhesive sheet composed of an adhesive layer; a multi-layer adhesive sheet in which a plurality of adhesive layers are laminated; and a multi-layer adhesive sheet in which other adhesive layers are laminated between the adhesive layers. material; a multi-layer adhesive sheet with a support laminated between the adhesive layer and the adhesive layer; a multi-layer adhesive sheet with an adhesive layer laminated on one side of the support and other adhesive layers laminated on the other side. When the double-sided adhesive sheet has a support, a transparent support should be used as the support. The support can be the same as the transparent base material, and a general film used in the optical field can be used. This kind of double-sided adhesive sheet also has excellent transparency as an adhesive sheet as a whole, and therefore can be suitably used for bonding optical members to each other.

When the adhesive sheet of the present invention is a single-sided adhesive sheet, as shown in FIG. 1 , the adhesive layer 11 may have a transparent base material 12 a on one side. At this time, the other side of the adhesive layer 11 is preferably covered with the release sheet 12b. When an adhesive sheet is used, it is preferable to peel off the release sheet 12b and attach it so that the adhesive layer 11 is closely adhered to the desired adherend, and then irradiate active energy rays or the like to perform post-hardening. As the transparent base material, films generally used in the optical field such as polyethylene terephthalate film, acrylic film, polycarbonate film, cellulose triacetate film, or cycloolefin polymer film can be used. In addition, an easy-adhesion layer can also be provided on the adhesive layer side of the transparent substrates. Furthermore, the transparent substrate can also be provided with functional layers such as a hard coating layer, an anti-reflective layer, an anti-fouling layer or an ultraviolet absorbing layer on the side opposite to the adhesive layer.

The present invention also relates to an adhesive sheet with a release sheet, which is provided with release sheets on both sides of the adhesive sheet. When the adhesive sheet of the present invention is provided with release sheets on both sides, as shown in FIG. 1 , it is preferable to have release sheets 12 a and 12 b on both sides of the adhesive layer 11 .

Examples of the release sheet include: a release laminated sheet having a release sheet base material and a release agent layer provided on one side of the release sheet base material; or a polyethylene film or polyethylene film as a low polarity base material. Polyolefin films such as acrylic films.

Among the peelable laminated sheets, paper or polymer film can be used as the base material for the peelable sheet. As the release agent constituting the release agent layer, for example, a general-purpose addition-type or condensation-type polysiloxane-based release agent or a compound containing a long-chain alkyl group can be used. In particular, it is advisable to use a highly reactive addition-type polysiloxane-based release agent.

Specific examples of polysilicone-based release agents include: BY24-4527, SD-7220, etc. manufactured by Dow Corning Toray Silicone; or KS-3600, KS-774, X62-2600, etc. manufactured by Shin-Etsu Chemical Industry Co., Ltd. In addition, the polysilicone stripper should preferably contain polysilicone resin, which is an organic resin having SiO ₂ units and (CH ₃ ) ₃ SiO _1/2 units or CH ₂ =CH(CH ₃ )SiO _1/2 units. Silicon compounds. Specific examples of the polysilicone resin include BY24-843, SD-7292, SHR-1404, etc. manufactured by Dow Corning Toray Silicone Co., Ltd.; or KS-3800, X92-183, etc. manufactured by Shin-Etsu Chemical Industry Co., Ltd.

Commercially available products can also be used as the peelable laminated sheet. For example, Teijin DuPont Films manufactures heavy release films that are release-treated polyethylene terephthalate films; or Teijin DuPont Films manufactures release-treated polyethylene terephthalate films. of light isolation film.

When the adhesive sheet of the present invention is a double-sided adhesive sheet, it is preferable to have a pair of peeling sheets with different peeling forces. That is, in order to make the peeling sheet easy to peel, it is preferable to make the peeling properties of the peeling sheet 12a and the peeling sheet 12b different. If the releasability from one of them is different from the releasability from the other, it is likely that only the release sheet with higher releasability will be peeled first. At this time, the peelability of the peeling sheet 12a and the peeling sheet 12b can be adjusted according to the lamination method or the lamination order.

Furthermore, the present invention also relates to an adhesive sheet with a transparent film, which is provided with a transparent film on at least one side of the adhesive sheet. In this case, the transparent film is preferably at least one selected from a polyethylene terephthalate film, an acrylic film, a polycarbonate film, a cellulose triacetate film, and a cyclic olefin polymer film. The adhesive sheet with a transparent film may be a sheet in which a transparent film/adhesive sheet/release sheet are laminated in this order.

＜Adhesive layer＞ The adhesive sheet of the present invention has an adhesive layer in which the adhesive composition is in a semi-hardened state, and the adhesive layer has post-hardening properties.

Here, in this specification, when the gel fraction of the adhesive layer can be increased by more than 10% by mass by irradiating active energy rays under the following conditions, the adhesive layer before irradiation is in a semi-hardened state. At this time, optically transparent PET spacers are attached to both sides of the adhesive layer, and active energy rays (high-pressure mercury lamps or metal halogen lamps) are irradiated from the side of one of the optically transparent PET spacers in such a way that the accumulated light intensity is 3000mJ/ ^cm2 . lamp).

Among them, the gel fraction of the adhesive layer in a semi-hardened state is preferably more than 10 mass% and less than 75 mass%, preferably more than 12 mass% and less than 75 mass%, and more preferably 15 to 70 mass%. In addition, the gel fraction of the post-hardened adhesive layer is preferably 60 to 100 mass%, preferably 65 to 100 mass%, and more preferably 70 to 100 mass%. In addition, the difference between the gel fraction of the adhesive layer in the semi-hardened state and the gel fraction after post-hardening is preferably more than 15%, and more preferably is more than 20%.

The gel fraction of the adhesive layer is a value measured using the following method. First, collect about 0.1g of the adhesive sheet (adhesive layer) in a sample bottle, add 30 ml of ethyl acetate, and shake for 24 hours. Then, the contents of the sample bottle were filtered out using a 150-mesh stainless steel wire mesh, the residue on the wire mesh was dried at 100° C. for 1 hour, and the dry mass (g) was measured. Using the following formula 1, the gel fraction was calculated from the obtained dry mass. Gel fraction (mass %) = (dry mass/collected mass of adhesive layer) × 100...Equation 1

In this specification, the "semi-hardened state" is preferably the state after thermal hardening. Furthermore, it is more ideal to perform "post-hardening" by irradiating active energy rays afterwards. That is, the adhesive layer of the adhesive sheet of the present invention is preferably in a semi-hardened state by thermally hardening the adhesive composition, and is preferably in an active energy ray curable state.

When the adhesive layer is irradiated with active energy rays at a cumulative light intensity of 3000mJ/ ^cm2 and then hardened, the adhesive layer satisfies the following physical properties (1) and (2); Physical properties (1): Tensile speed 10mm/min The elongation at break in the tensile test measurement is less than 500%; Physical properties (2): Measured using the following measurement conditions at i) 85°C, relative humidity 85% and ii) 85°C, relative humidity less than 10%. The load peeling distance is less than 50mm: (Measurement conditions) The area of 25mm width and 75mm length in the adhesive surface of the adhesive layer with a width of 25mm and a length of 100mm is attached to the adherend and then hardened. Under each environment of i) 85℃, relative humidity 85% and ii) 85℃, relative humidity less than 10%, fix the adherend in the horizontal direction by hanging the non-adhesive area of the adhesive layer downward. Apply a load of 100g to the length-direction end of the non-laminated area of the adhesive layer for 5 minutes, and measure the peeling distance of the adhesive layer's bonded area from the adherend during the period, as i) 85°C, relative humidity 85% and ii) Peeling distance of each load under 85℃ and relative humidity less than 10%.

The above-mentioned physical property (1) (elongation at break) only needs to be less than 500%, preferably 490% or less, more preferably 480% or less. Here, the elongation at break is measured in accordance with JIS K 7161-1. At this time, the stretching speed was set to 10 mm/min, and the measurement was performed at 23° C. and a relative humidity of 50%. Moreover, the following was used for the measurement sample: the adhesive layer with a thickness of 25 micrometers, a width of 60 mm, and a length of 200 mm was rounded in the longitudinal direction, and processed into the cylindrical shape with a cross-sectional area of 5 mm ^<2> and a height of 60 mm. The sample was stretched so that the distance between the chucks was 30 mm, and the elongation when the sample was broken was defined as the elongation at break. In addition, as the measuring device, for example, AUTOGRAPH AGS-X manufactured by Shimadzu Corporation can be used.

Regarding the measurement of the above-mentioned physical property (2) (peel distance under constant load), in detail, first, a test piece for measurement is prepared using the following method. Using a hand ink roller, a cellulose triacetate film (manufactured by FUJIFILM, FUJITAC TD60UL, thickness 60 μm) was attached to one side of the adhesive layer to produce a laminated film. Cut the laminated film into a size of 25mm in width and 100mm in length. Next, use a 2kg crimping roller to stick the area of 25mm in width and 100mm in length on the other side of the adhesive layer to the adherend. (Polycarbonate plate with hard coating: Made by Mitsubishi Gas Chemical Co., Ltd., IUPILON MR58, thickness 1mm) The hard-coated side. In this state, it was kept in an autoclave at 40° C. and 5 atmospheres for 30 minutes to adhere closely to the adherend.

In the above-mentioned measurement conditions, during post-curing, ultraviolet rays are irradiated from the cellulose triacetate film side of the test piece for measurement so that the accumulated light amount becomes 3000 mJ/cm ² .

Then, after placing it in an environment of i) 85℃, relative humidity 85% and ii) 85℃, relative humidity less than 10% for 24 hours respectively, place it in an environment of i) 85℃, relative humidity 85% and ii) 85℃, relative humidity. When the environment is less than 10%, hang the 100g weight 34 on the lengthwise end of the non-laminated area (width 25mm, length 25mm) of the laminated film as shown in Figure 4, and place it on the plane relative to the adherend 32. Apply a load of 100g in the direction of 90° and leave it in this state for another 5 minutes. The length L (peel distance under constant load) of the point where the laminated film has been peeled off was measured respectively.

The constant load peeling distance measured under i) 85°C and 85% relative humidity using the above measurement conditions is 50 mm or less, and is preferably 45 mm or less, preferably 40 mm or less, more preferably 35 mm or less, especially 30 mm or less. In addition, the constant load peeling distance at ii) 85° C. and relative humidity less than 10% is 50 mm or less, and is preferably 45 mm or less, preferably 40 mm or less, more preferably 35 mm or less, especially 30 mm or less. In addition, the constant load peeling distance at i) 85°C and relative humidity of 85% and ii) 85°C and relative humidity of less than 10% can also be 0 mm respectively.

In the present invention, when the adhesive layer is irradiated with active energy rays at a cumulative light intensity of 3000 mJ/cm ² and then hardened, the adhesive layer should satisfy the following physical properties (3) in addition to the above physical properties (1) and (2). ).

Physical properties (3): The probe viscosity value is below 1.0N/5mmφ.

(Measurement conditions for probe viscosity value) Measuring machine: NS probe viscosity testing machine (manufactured by NICHIBAN Co., Ltd.) Probe diameter: 5mmφ Probe base material: Stainless steel surface finishing AA#400 grinding mirror Scale weight: 19.6±0.2g (made of brass) Probe moving speed: 1.0cm/second Dwell time: 1 second

The probe viscosity value of the above-mentioned post-hardened adhesive layer is preferably below 1.0N/5mmφ, and more preferably below 0.5N/5mmφ. In addition, the lower limit of the probe viscosity value is not particularly limited. For example, it is more preferably 0.1N/5mmφ or more, and particularly preferably 0.01N/5mmφ or more. By setting the probe viscosity value of the post-hardened adhesive layer within the above range, workability is excellent and workability is also improved.

The thickness of the adhesive layer can be appropriately set according to the purpose and is not particularly limited. Preferably, it is 5~150 μm, more preferably 8~100 μm, and particularly preferably 10~80 μm. By setting the thickness of the adhesive layer within the above range, bleeding or stickiness of the adhesive can be suppressed, thereby improving processability. Furthermore, by setting the thickness of the adhesive layer within the above range, the production of the double-sided adhesive sheet becomes easier.

＜Adhesive composition＞ The above-mentioned adhesive layer is one in which the adhesive composition is in a semi-hardened state. The adhesive composition used in the present invention is a dual-hardening adhesive composition. The adhesive composition contains: cross-linked acrylic copolymer A with an acid component (however, the glass transition temperature (Tg) is -40°C or above); cross-linking agent B; and a cross-linking acrylic copolymer with two or more reactive double bonds in the molecule. Multifunctional monomer C; monofunctional monomer D having one reactive double bond in the molecule; and photopolymerization initiator E.

(Crosslinkable acrylic polymer A) The crosslinkable acrylic polymer A is not particularly limited as long as it has an acrylic monomer unit containing an acid component and the glass transition temperature (Tg) is -40°C or higher. acrylate unit (a1) and an acrylic monomer unit (a2) having a cross-linkable functional group containing an acid component that are copolymerized. The crosslinkable acrylic polymer A should preferably have transparency that does not reduce the visibility of the display device. In addition, in this specification and the scope of the patent application, "unit" refers to the repeating unit (monomer unit) constituting the polymer.

The non-crosslinked (meth)acrylate unit (a1) is a repeating unit derived from an alkyl (meth)acrylate. (Meth)acrylic acid alkyl esters include: (meth)acrylic acid methyl ester, (meth)acrylic acid ethyl ester, (meth)acrylic acid propyl ester, (meth)acrylic acid isopropyl ester, (meth)acrylic acid n-butyl ester, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate Ester, n-octyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, n-decyl (meth)acrylate, (meth)acrylate ) Isodecyl acrylate, n-Undecyl (meth)acrylate, n-dodecyl (meth)acrylate, stearyl (meth)acrylate, methoxyethyl (meth)acrylate, Ethoxyethyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, etc. These may be used individually by 1 type, and may be used in combination of 2 or more types.

Among the above-mentioned alkyl (meth)acrylates, from the viewpoint of improved adhesion, it is preferable to be selected from the group consisting of methyl (meth)acrylate, n-butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. At least one of the esters.

In the present invention, the crosslinkable functional group of the crosslinkable acrylic polymer contains an acid component. Here, the crosslinkable functional group constituting the acid component is preferably a carboxyl group or a group derived from a carboxyl group, or a sulfonic acid group or a group derived from a sulfonic acid group, and is particularly preferably a carboxyl group. That is, the acrylic monomer unit (a2) having a crosslinkable functional group containing an acid component is preferably a carboxyl group-containing monomer unit. Examples of monomer units containing carboxyl groups include acrylic acid and methacrylic acid.

In addition, the crosslinkable functional group possessed by the crosslinkable acrylic polymer A may have a functional group other than the crosslinkable functional group constituting the acid component. Examples of other functional groups include: hydroxyl, amine, amide, epoxypropyl or isocyanate groups.

The content of the acrylic monomer unit (a2) having a crosslinkable functional group containing an acid component in the cross-linked acrylic polymer A is preferably 0.01 to 40 mass %, more preferably 0.5 to 35 mass %. If the content of the acrylic monomer unit (a2) having a crosslinkable functional group containing an acid component is more than the lower limit of the above range, the crosslinkability necessary to maintain the semi-hardened state can be fully exerted. If If it is below the upper limit of the above range, it is easy to maintain the necessary adhesiveness.

The crosslinkable acrylic polymer A may also have other monomer units if necessary. Other monomers may be used as long as they can be copolymerized with the above-mentioned acrylic monomer, and examples include (meth)acrylonitrile, vinyl acetate, styrene, vinyl chloride, vinylpyrrolidone, vinylpyridine, and the like. The content of other monomer units in the crosslinkable acrylic polymer is preferably 20 mass% or less, more preferably 15 mass% or less.

The glass transition temperature (Tg) of the crosslinkable acrylic polymer A is -40°C or higher, preferably -38°C or higher, and more preferably -35°C or higher. The upper limit of the glass transition temperature (Tg) is not limited, but may be 0° C. or lower, for example. By setting the glass transition temperature (Tg) of the crosslinkable acrylic polymer A in the above range, the processability of the adhesive sheet can be more effectively improved.

The specific glass transition temperature can be a literature value or a value that has measured the glass transition temperature of the cross-linked acrylic polymer A using DSC (differential scanning calorimeter).

The weight average molecular weight of the crosslinkable acrylic polymer A is preferably 100,000 to 2,000,000, more preferably 200,000 to 1,500,000. If the weight average molecular weight is within the above range, the semi-hardened state of the adhesive layer can be easily maintained, hardness after post-hardening can be easily generated, and workability is excellent. In addition, the weight average molecular weight of the crosslinkable acrylic polymer A is the value before crosslinking with a crosslinking agent. The weight average molecular weight is measured using particle size sieve chromatography (SEC) and is a value obtained based on a polystyrene based standard. A commercially available crosslinkable acrylic polymer may be used, or one synthesized by a known method may be used.

The acid value of the crosslinkable acrylic polymer A is preferably 1 mgKOH/g or more, preferably 2 mgKOH/g or more, more preferably 3 mgKOH/g or more. In addition, the acid value of the crosslinkable acrylic polymer A is preferably 200 mgKOH/g or less. In addition, in the present invention, the acid value of the adhesive layer formed of the adhesive composition is preferably within the above range.

The acid value of the crosslinkable acrylic polymer A is calculated by the following method. First, weigh accurately using a precision balance in a 100 ml Erlenmeyer flask so that the solid content of the cross-linked acrylic polymer A as the sample is about 2 g, and add toluene/2-propanol/water=5/5/ Dissolve with 10 ml of mixed solvent of 0.5 (weight ratio). Next, add 1 to 3 drops of p-naphthol-benzene solution as an indicator into the container, and stir thoroughly until the sample becomes uniform. Titrate it with 0.1N potassium hydroxide-2-propanol solution, and set the end point of neutralization when the light red color of the indicator lasts for 30 seconds. The value obtained from this result using the following equation (1) was taken as the acid value of the sample.

Acid value (mgKOH/g)=[cKOH×(V1-V0)×5.611]/S (1) In the formula (1), cKOH is the molar concentration (mol/L) of the 0.1N potassium hydroxide-2-propanol solution, and V1 is the molar concentration of the 0.1mol/L potassium hydroxide-2-propanol solution required for the titration of the sample. The amount (mL), V0 is the amount of 0.1mol/L potassium hydroxide-2-propanol solution required for the titration of the blank test (mL), and S is the collection amount of the sample (g).

(Crosslinking agent B) The adhesive composition contains a cross-linking agent. The crosslinking agent can be appropriately selected taking into consideration the reactivity with the crosslinkable functional group that the crosslinkable acrylic polymer A has. For example, it can be selected from known cross-linking agents such as isocyanate compounds, epoxy compounds, tetrazoline compounds, aziridine compounds, metal chelate compounds, butylated melamine compounds, and the like. Among these, epoxy compounds are preferably used from the viewpoint of being able to easily cross-link carboxyl group-containing acrylates. That is, the crosslinking agent is preferably a bifunctional or higher epoxy compound.

Examples of the epoxy compound include: ethylene glycol diepoxypropyl ether, polyethylene glycol diepoxypropyl ether, propylene glycol diepoxypropyl ether, polypropylene glycol diepoxypropyl ether, and glycerol bicyclo Oxypropyl ether, neopentyl glycol diepoxypropyl ether, 1,6-hexanediol diepoxypropyl ether, tetraepoxypropyl stubble diamine, 1,3-bis(N,N-di Glycidyl aminomethyl) cyclohexane, trimethylolpropane polyglycidyl ether, diglyceryl polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitol polyglycidyl ether Ether etc.

The content of the cross-linking agent in the adhesive composition can be appropriately selected according to the desired adhesiveness, etc., and is preferably 0.01 to 5 parts by mass, more preferably 0.01 to 3 parts by mass based on 100 parts by mass of the cross-linked acrylic polymer. . By setting the content of the crosslinking agent within the above range, adhesion to the base material can be improved, and processability can be further improved. In addition, one type of cross-linking agent may be used alone, or two or more types may be used in combination. When two or more types are used in combination, the total mass is preferably within the above range.

(Polyfunctional monomer C) The adhesive composition contains a multifunctional monomer C having two or more reactive double bonds in the molecule.

Examples of the polyfunctional monomer C include: ethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,4 -Butanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,6-hexanediol diacrylate, polybutylene glycol di(meth)acrylate, Neopentyl glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, bisphenol A diepoxy Propyl ether diacrylate, trimethylolpropane tri(meth)acrylate, neopentyl erythritol tri(meth)acrylate, neopenterythritol tetra(meth)acrylate and other polyols (methane) base) acrylates, vinyl methacrylate, etc.

The multifunctional monomer C has more than 2 reactive double bonds. Among them, the multifunctional monomer preferably has more than 2 and less than 5 reactive double bonds, and more preferably has more than 2 and less than 4 reactive double bonds.

A commercially available product can be used as the polyfunctional monomer C. Examples of commercially available products include: trifunctional monomer M310 (trimethylolpropane PO-modified triacrylate) manufactured by Toagosei Co., Ltd. or trifunctional monomer M321 (trimethylolpropane epoxypropane-modified triacrylate). ester), bifunctional monomer M211B (bisphenol A EO modified diacrylate) manufactured by Toagosei Co., Ltd., etc.

The multifunctional monomer C may also have a bisphenol skeleton in one molecule. By using a multifunctional monomer with a bisphenol skeleton in one molecule, the hardness of the post-cured adhesive layer can be more effectively increased, and the processability of the adhesive sheet can be easily improved.

Examples of such polyfunctional monomer C include: diacrylate of bisphenol A diepoxypropyl ether, diacrylate of propoxylated bisphenol A, and diacrylate of bisphenol F diepoxypropyl ether. wait.

When the polyfunctional monomer C is used as a homopolymer, the glass transition temperature (Tg) is preferably 30°C or higher, more preferably 50°C or higher. When the polyfunctional monomer is used as a homopolymer, the glass transition temperature (Tg) may be, for example, 300°C or lower. By setting the glass transition temperature (Tg) of the polyfunctional monomer C into a homopolymer within the above range, the processability of the adhesive sheet can be more effectively improved.

In addition, the glass transition temperature in this specification refers to the glass transition temperature when polyfunctional monomer C is made into a homopolymer. The specific glass transition temperature can be based on literature values, or can be measured by DSC (Differential Scanning Calorimetry) after the polyfunctional monomer C is made into a homopolymer with a weight average molecular weight of more than 10,000. The value of the glass transition temperature of an object.

The content of the multifunctional monomer C in the adhesive composition is preferably 10 to 40 parts by mass, preferably 10 to 30 parts by mass, and more preferably 10 to 25 parts by mass relative to 100 parts by mass of the cross-linked acrylic polymer A. The above-mentioned polyfunctional monomer C may be used alone or in combination of two or more types. When two or more types are used in combination, the total mass is preferably within the above range. By setting the content of the polyfunctional monomer C within the above range, the aforementioned physical properties (1) to (3) can be easily achieved and the high temperature and high humidity durability can be improved. Furthermore, by setting the content of the multifunctional monomer C within the above range, the hardness of the post-hardened adhesive layer can be more effectively increased, and the processability of the adhesive sheet can be improved.

(Monofunctional monomer D) The adhesive composition contains monofunctional monomer D having one reactive double bond in the molecule.

Examples of the monofunctional monomer D include isocamphenyl acrylate, isostearyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, benzyl methacrylate, and N-acrylyloxy. Ethyl hexahydrophthalamide, acrylamide, N,N-dimethylacrylamide, N,N-diethylacrylamide, acrylmorpholine, vinylpyrrolidone, etc. Among them, the monofunctional monomer is preferably an alkyl (meth)acrylate, and preferably at least one selected from isocamphenyl acrylate and isostearyl acrylate, and more preferably isocamphenyl acrylate. Examples of commercially available monofunctional monomer D include DEAA manufactured by KJ Chemicals Co., Ltd., IBXA manufactured by Osaka Organic Chemical Industry Co., Ltd., and the like.

When the monofunctional monomer D is used as a homopolymer, the glass transition temperature (Tg) is preferably 50°C or more and less than 200°C, more preferably 55°C or more and less than 180°C.

The content of the monofunctional monomer D is preferably 10 to 40 parts by mass, preferably 10 to 30 parts by mass, and more preferably 10 to 20 parts by mass relative to 100 parts by mass of the crosslinkable acrylic polymer A. One type of monofunctional monomer D may be used alone, or two or more types may be used in combination. When two or more types are used in combination, the total mass is preferably within the above range.

(Photopolymerization initiator E) The adhesive composition contains photopolymerization initiator E. The photopolymerization initiator is preferably one that starts polymerization of the crosslinkable acrylic polymer or multifunctional monomer by active energy ray irradiation. As the photopolymerization initiator E, a known photopolymerization initiator can be used.

Here, the so-called "active energy ray" means an electromagnetic wave or a charged particle beam containing energy quanta, and examples thereof include ultraviolet rays, electron beams, visible rays, X-rays, ion beams, etc. Among them, from the viewpoint of versatility, ultraviolet rays or electron beams are preferred, and ultraviolet rays are particularly preferred.

Examples of the photopolymerization initiator E include acetophenone-based initiators, benzoin ether-based initiators, benzophenone-based initiators, hydroxyalkylphenone-based initiators, thioxanthone-based initiators, and amine-based initiators. , acylphosphine oxide initiator, etc.

Specific examples of the acetophenone-based initiator include diethoxyacetophenone, benzildimethyl ketal, and the like.

Specific examples of benzoin ether initiators include benzoin, benzoin methyl ether, and the like.

Specific examples of the benzophenone-based initiator include benzophenone, methyl o-phenylbenzoate, and the like.

Specific examples of the hydroxyalkylphenone-based initiator include 1-hydroxy-cyclohexyl-phenyl-ketone (manufactured by BASF Corporation of Japan and commercially available as IRGACURE 184).

Specific examples of the thioxanthone-based initiator include 2-isopropylthioxanthone, 2,4-dimethylthioxanthone, and the like.

Specific examples of the amine initiator include triethanolamine, ethyl 4-dimethylbenzoate, and the like.

Specific examples of the acylphosphine oxide-based initiator include phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (manufactured by BASF Corporation of Japan and commercially available as IRGACURE819).

The content of the photopolymerization initiator E in the adhesive composition is preferably 0.05 to 10 parts by mass, more preferably 0.1 to 5 parts by mass relative to 100 parts by mass of the cross-linked acrylic polymer. If it is above the lower limit, post-hardening can be used to adjust the desired hardness, and the molecular weight after post-hardening can be set in an appropriate range. Therefore, an adhesive sheet with excellent processability can be produced. One type of photopolymerization initiator may be used alone, or two or more types may be used in combination. When two or more types are used in combination, the total mass is preferably within the above range.

(solvent) The adhesive composition may also contain solvents. At this time, the solvent is used to improve the coating suitability of the adhesive composition. Examples of solvents include: hydrocarbons such as hexane, heptane, octane, toluene, xylene, ethylbenzene, cyclohexane, and methylcyclohexane; methylene chloride, trichloroethane, trichloroethylene, tetrachloroethylene, etc. Halogenated hydrocarbons such as vinyl chloride and dichloropropane; alcohols such as methanol, ethanol, propanol, isopropanol, butanol, isobutanol, and diacetone alcohol; diethyl ether, diisopropyl ether, and dimethane , tetrahydrofuran and other ethers; acetone, methyl ethyl ketone, methyl isobutyl ketone, isophorone, cyclohexanone and other ketones; methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, acetic acid Esters such as amyl ester and ethyl butyrate; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, Polyols such as propylene glycol monomethyl ether acetate and their derivatives.

The content of the solvent in the adhesive composition is not particularly limited. It is preferably 25 to 500 parts by mass, and more preferably 30 to 400 parts by mass relative to 100 parts by mass of the cross-linked acrylic polymer A.

In addition, the content of the solvent is preferably 10 to 90 mass %, more preferably 20 to 80 mass %, based on the total mass of the adhesive composition. One type of solvent may be used alone, or two or more types may be used in combination. When two or more types are used in combination, the total mass is preferably within the above range.

(other ingredients) The adhesive composition may also contain other components than the above within the range that does not impair the effect of the present invention. Examples of other components include known components that are additives for adhesives. For example, if necessary, it may be selected from plasticizers, antioxidants, metal corrosion inhibitors, adhesion agents, silane coupling agents, ultraviolet absorbers, light stabilizers such as hindered amine compounds, and the like. In addition, dyes or pigments may be added for the purpose of coloring.

Examples of plasticizers include: vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caproate, vinyl octanoate, vinyl caprate, vinyl laurate, vinyl myristate, and vinyl palmitate. , vinyl stearate, vinyl cyclohexane carboxylate, vinyl carboxylates like vinyl benzoate, or styrene, etc.

Examples of antioxidants include phenolic antioxidants, amine antioxidants, lactone antioxidants, phosphorus antioxidants, and sulfur antioxidants. One type of these antioxidants may be used alone, or two or more types may be used in combination.

From the perspective of high compatibility or high effectiveness of the adhesive, benzotriazole-based resins are preferred examples of metal corrosion inhibitors.

Examples of the tackifier include rosin-based resins, terpene-based resins, terpene-phenol-based resins, lavender-indene-based resins, styrene-based resins, xylene-based resins, phenol-based resins, petroleum resins, and the like.

Examples of the silane coupling agent include mercaptoalkoxysilane compounds (for example, mercapto-substituted alkoxy oligomers, etc.).

Examples of ultraviolet absorbers include benzotriazole compounds, benzophenone compounds, and the like. However, when ultraviolet rays are used as active energy rays during post-hardening, it is appropriate to add them within a range that does not hinder the polymerization reaction.

＜Manufacturing method of adhesive sheet＞ The manufacturing method of the adhesive sheet of the present invention preferably includes the following steps: applying the above-mentioned adhesive composition on the release sheet to form a coating film; and heating the coating film to a semi-hardened state. By heating the coating film, the reaction between the cross-linked acrylic polymer A and the cross-linking agent B proceeds, and a cured product (adhesive layer) in a semi-hardened state is formed. That is, during heating, the polymerization reaction of the monomer using the photopolymerization initiator E does not proceed in the coating film, or even if it does, the polymerization reaction is only in trace amounts. Therefore, the monomers C and D and the photopolymerization initiator contained in the adhesive composition At least part of E will be included in the adhesive layer in an unreacted state. The adhesive sheet of the present invention preferably has post-hardening properties and active energy ray hardening properties.

In addition, in order to keep the adhesive composition in a semi-hardened state, after removing the solvent after coating, it is advisable to perform an aging treatment in which the adhesive sheet is allowed to stand at a certain temperature for a certain period of time. The aging treatment can be performed, for example, by leaving it standing at 23° C. for 7 days.

Coating of the adhesive composition can be carried out using a known coating device. Examples of the coating device include: blade coater, air knife coater, roll coater, rod coater, gravure coater, microgravure coater, rod blade coater, die lip Coating machine, mold coating machine, curtain coating machine, etc.

The coating film formed by applying the adhesive composition can be heated using known heating devices such as a heating furnace and an infrared lamp.

＜How to use adhesive sheet＞ In the method of using the adhesive sheet of the present invention, it is preferable to bring the adhesive layer of the adhesive sheet into contact with the surface of the adherend. In the method of using the adhesive sheet, it is more ideal that the adhesive layer of the adhesive sheet is in a semi-hardened state and adhered to the adherend, and then irradiated with active energy rays to harden the adhesive layer. That is, the adhesive sheet of the present invention is a two-stage hardening adhesive sheet, which has an adhesive layer that is semi-cured by heat only before lamination, and the adhesive layer is cured by active energy rays after lamination.

＜Use of adhesive sheet＞ The adhesive sheet of the present invention is preferably used for laminating optical members that require durability and must be formed after being laminated with the optical member.

After the adhesive sheet of the present invention is bonded to an adherend such as a base material and then hardened, it has excellent base material adhesion and durability even when exposed to a high temperature and high humidity environment, so it can suppress floating or The occurrence of flaking. For example, after the adhesive sheet of the present invention is bonded to a polycarbonate base material and then hardened, it can prevent it from floating or peeling off the polycarbonate base material even if it is exposed to a high temperature and high humidity environment.

The adhesive sheet of the present invention can also be bonded to optical components such as polarizing plates. Here, the so-called polarizing plate includes a polarizer and a polarizer protective film, and the adhesive sheet of the present invention is preferably bonded to the polarizer protective film. Examples of polarizer protective films include: cycloolefin-based resin films, cellulose acetate-based resin films such as cellulose triacetate and cellulose diacetate, polyethylene terephthalate, polyethylene naphthalate, polyp- Polyester resin films such as butylene phthalate, polycarbonate resin films, acrylic resin films, polypropylene resin films, etc.

[Laminated body] The present invention also relates to a laminated body having the above-mentioned adhesive sheet and an adherend. The laminated body includes: an adhesive layer that is hardened by irradiating active energy rays to the adhesive layer of the adhesive sheet; and an adherend on at least one side of the hardened adhesive layer. That is, the laminated body of the present invention has an adhesive sheet and an adherend provided on at least one side of the adhesive sheet. The adhesive layer of the adhesive sheet is hardened by irradiation with active energy rays. When the adhesive sheet is a double-sided adhesive sheet, it is appropriate to irradiate active energy rays in a state where the adhesive sheet in a semi-hardened state is bonded to two adherends to post-harden the adhesive layer to form a laminate. . Here, the adherend is more preferably a base material and an optical member, and is particularly preferably a polycarbonate base material, a polarizing plate, a transparent film, a transparent resin or glass.

FIG. 2 is a schematic cross-sectional view showing an example of the laminated body of the present invention. FIG. 2 is a cross-sectional view showing an example of the structure of a laminate 20 in which the adhesive sheet 21 of the present invention is bonded to a base material 22 and an optical member 24. As shown in FIG. 2 , the adhesive sheet 21 of the present invention is suitable for laminating to the base material 22 , and is also suitable for laminating the base material 22 to other optical components 24 . In addition, the adhesive sheet 21 of the present invention can also be used to bond with polarizing plates.

Examples of the optical components contained in the laminate include components in optical products such as touch panels and image display devices, and anti-shattering films attached to the surface cover of the outermost layer. Examples of components of a touch panel include an ITO film in which an ITO film is provided on a transparent resin film, ITO glass in which an ITO film is provided on the surface of a glass plate, and a transparent resin film in which a conductive polymer is coated. Conductive film, hard coat film, fingerprint-resistant film, etc. Examples of components of an image display device include antireflection films, orientation films, polarizing films, retardation films, and brightness enhancement films used in liquid crystal display devices.

Examples of materials used in these components include: glass, polycarbonate, polyethylene terephthalate, polymethyl methacrylate, polyethylene naphthalate, cyclic olefin polymers, and cellulose triacetate. , polyimide, cellulose amide, etc.

When the adhesive sheet of the present invention is a double-sided adhesive sheet, it can be used to bond two adherends. At this time, the adhesive sheet of the present invention can be used to bond transparent optical films inside the touch panel, to bond the transparent optical film to glass, and to bond the transparent optical film of the touch panel to the liquid crystal panel. , lamination of cover glass and transparent optical film, lamination of cover glass and transparent optical film, etc., it is useful when any of the components is a polycarbonate base material. As the transparent optical film, films generally used in the optical field such as polyethylene terephthalate film, acrylic film, polycarbonate film, cellulose triacetate film, or cycloolefin polymer film can be used. In addition, a hard coat layer may be provided on a transparent optical film or a polycarbonate base material.

FIG. 3 is a schematic cross-sectional view showing another example of the laminated body of the present invention. As shown in FIG. 3 , the adherend may also have stepped portions (27a, 27b, 27c, 27d). In Fig. 3, the base material has stepped portions (27a, 27b), and the optical member has stepped portions (27c, 27d). In addition, the thickness of the drop portion (27a, 27b, 27c, 27d) is usually 5 to 60 μm. Accordingly, the adhesive sheet 21 of the present invention can also be attached to a member having a drop portion, and can cater to the unevenness generated from the drop portion.

[Manufacturing method of laminated body] The manufacturing method of the laminated body includes the following steps: after bonding the adhesive layer of the above-mentioned adhesive sheet to the adherend in a semi-hardened state, irradiating active energy rays to post-harden the adhesive layer. That is, the manufacturing method of the laminated body of the present invention sequentially includes: step 1, layering a volume to be adhered on at least one side of the adhesive sheet; and step 2, irradiating the adhesive layer of the adhesive sheet with active energy rays , causing the aforementioned adhesive layer to harden. Before irradiation with active energy rays, the adhesive layer of the adhesive sheet is in a semi-hardened state, so the initial adhesion to the base material is good. Accordingly, after the adhesive sheet is attached to the adherend, the active energy rays are used to harden the adhesive layer, thereby increasing the cohesion of the adhesive layer and improving the adhesion to the adherend. In addition, the post-hardened adhesive layer prevents deformation or strain of the substrate.

Examples of active energy rays include ultraviolet rays, electron beams, visible rays, X-rays, ion beams, etc., and can be appropriately selected according to the photopolymerization initiator contained in the adhesive layer. Among them, from the viewpoint of versatility, ultraviolet rays or electron beams are preferred, and ultraviolet rays are particularly preferred.

Examples of ultraviolet light sources include high-pressure mercury lamps, low-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, carbon arcs, xenon arcs, and electrodeless ultraviolet lamps. For example, electron beams emitted from various electron beam accelerators such as Kirkclough-Walton type, Vandegraaf type, resonance transformer type, insulated core transformer type, linear type, high frequency and high voltage type, and high frequency type can be used. electron beam.

The irradiation output of ultraviolet rays should be set to the accumulated light amount of 100~10000mJ/ ^cm2 , and more preferably 500~5000mJ/ ^cm2 . In addition, in the present invention, when measuring the above-mentioned physical properties (1) to (3), active energy rays are irradiated in such a manner that the accumulated light amount constitutes 3000 mJ/cm ² . Example

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

<Synthesis of cross-linked acrylic polymer A (A-1)> By solution polymerization in ethyl acetate, crosslinkable acrylic polymer A (A-1) having an acid component was produced. Specifically, butyl acrylate monomer (BA), methyl acrylate monomer (MA), methyl methacrylate (MMA), and acrylic acid (AA) are composed of a mass ratio of 90:1:4:6. The solution is blended and AIBN (azobisisobutyronitrile) as a radical polymerization initiator is dissolved in the solution. The solution was heated to 60° C. to perform random copolymerization to obtain a cross-linked acrylic polymer A (A-1).

The solution viscosity of the 21% by mass solution of the cross-linked acrylic polymer A (A-1) at 23°C is 4900 mPa. s. Moreover, the glass transition temperature (Tg) of the crosslinkable acrylic polymer A (A-1) was -21°C.

<Synthesis of cross-linked acrylic polymer A (A-2)> By solution polymerization in ethyl acetate, crosslinkable acrylic polymer A (A-2) having an acid component was produced. Specifically, butyl acrylate monomer (BA), methyl acrylate monomer (MA), methyl methacrylate (MMA), and acrylic acid (AA) are composed of a mass ratio of 90:3:4:3. The solution is blended and AIBN (azobisisobutyronitrile) as a radical polymerization initiator is dissolved in the solution. The solution was heated to 60° C. to perform random copolymerization to obtain a cross-linked acrylic polymer A (A-2).

The solution viscosity of the 21% by mass solution of the cross-linked acrylic polymer A (A-2) at 23°C is 5400 mPa. s. Furthermore, the glass transition temperature (Tg) of the crosslinkable acrylic polymer A (A-2) is -30°C.

<Synthesis of cross-linked acrylic polymer A (A-3)> By solution polymerization in ethyl acetate, a crosslinkable acrylic polymer A (A-3) without an acid component was produced. Specifically, 2-methoxyethyl acrylate monomer (MEA), 2-hydroxyethyl acrylate monomer (2HEA), methyl methacrylate (MMA), and diethyl acrylamide (DEAA) and butyl acrylate (BA) are blended in a mass ratio of 70:10:10:5:5, and AIBN (azobisisobutyronitrile) as a radical polymerization initiator is dissolved in the solution. The solution was heated to 60° C. to perform random copolymerization to obtain a cross-linked acrylic polymer A (A-3).

The solution viscosity of the 35 mass% solution of the cross-linked acrylic polymer A (A-3) at 23°C is 2000 mPa. s. Furthermore, the glass transition temperature (Tg) of the crosslinkable acrylic polymer A (A-3) is -30°C.

[Example 1] To 100 parts by mass of the crosslinkable acrylic polymer A (A-1), 0.05 parts by mass of an epoxy compound (manufactured by Mitsubishi Gas Chemical Co., Ltd., TETRAD X) as the crosslinking agent B, and as the polyfunctional monomer C were added 12 parts by mass of ethylene oxide modified diacrylate (manufactured by Toagosei Co., Ltd., ARONIX M211B, Tg=75°C), and isocamphenyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., IBXA, Tg) as the monofunctional monomer D =97°C) 12 parts by mass and 0.7 parts by mass of 1-hydroxy-cyclohexyl-phenyl-one (manufactured by BASF Japan, IRGACURE184) (abbreviated as "Irg184") as the photopolymerization initiator E, with a solid content concentration of 24 Add ethyl acetate as a solvent in a mass % manner to prepare an adhesive composition.

The above-mentioned adhesive composition was coated on the first release sheet (heavy release film, manufactured by Teijin DuPont Films, a release-treated polyethylene terephthalate film). Coating was performed using a Doctor Blade YD type manufactured by Yoshimitsu Seiki Co., Ltd. so that the thickness after drying would be 25 μm. Then, use a hot air dryer to dry at 100° C. for 3 minutes to remove the solvent and form an adhesive sheet having a semi-hardened adhesive layer.

A second release sheet (light release film, manufactured by Teijin DuPont Films), which has higher releasability than the first release sheet and has been subjected to a release treatment, is bonded to one side of the adhesive sheet to obtain an attached product. The adhesive sheet of the peeling sheet is the adhesive sheet of Example 1.

[Example 2] In Example 1, except that the addition amount of the polyfunctional monomer C was changed to 15 parts by mass, the adhesive composition and the adhesive sheet with a release sheet were prepared in the same manner as in Example 1.

[Example 3] In Example 1, except that the addition amount of the polyfunctional monomer C was changed to 20 parts by mass, the adhesive composition and the adhesive sheet with a release sheet were prepared in the same manner as in Example 1.

[Example 4] In Example 1, except that the cross-linked acrylic polymer A was changed from (A-1) to (A-2), the adhesive composition and the release sheet were obtained in the same manner as in Example 1. Adhesive sheet.

[Comparative example 1] In Example 1, except that the addition amount of the polyfunctional monomer C was changed to 15 parts by mass and that the monofunctional monomer D was not added, the adhesive composition and peeling agent were prepared in the same manner as in Example 1. Adhesive sheet of sheet material.

[Comparative example 2] With respect to 100 parts by mass of the crosslinkable acrylic polymer A (A-3), 0.5 parts by mass of a stubble diisocyanate compound (manufactured by Mitsui Chemicals, TAKENATE D-110N) as the crosslinking agent B was added as a polyfunctional 15 parts by mass of trimethylolpropane oxypropane-modified triacrylate (manufactured by Toagosei Co., Ltd., ARONIX M321, Tg=50°C) as monomer C, isocamphenyl acrylate as monofunctional monomer D (Osaka Organic Chemicals Composed of 15 parts by mass of IBXA (manufactured by Industrial Co., Ltd., Tg=97°C) and 0.7 parts by mass of 1-hydroxy-cyclohexyl-phenyl-one (manufactured by BASF Japan, IRGACURE 184) as the photopolymerization initiator E, in terms of solid content concentration Ethyl acetate was added as a solvent at 40% by mass to prepare an adhesive composition. Except for this, the same conditions were used as in Example 1 to prepare an adhesive composition and an adhesive sheet with a release sheet.

[Comparative example 3] In Comparative Example 2, except that the polyfunctional monomer C was changed to ethylene oxide modified diacrylate (manufactured by Toagosei Co., Ltd., ARONIX M211B, Tg=75°C), and the photopolymerization initiator E was not added, In the same manner as in Comparative Example 2, an adhesive composition and an adhesive sheet with a release sheet were produced.

[Measurement and evaluation] ＜Acid value＞ In a 100 ml Erlenmeyer flask, use a precision balance to accurately weigh the adhesive composition so that the solid content of the cross-linked acrylic polymer A prepared above as a sample is about 2 g, and add toluene/2-propanol/ Dissolve with 10ml of mixed solvent of water = 5/5/0.5 (weight ratio). Next, add 1 to 3 drops of p-naphthol-benzene solution as an indicator into the container, and stir thoroughly until the sample becomes uniform. Titrate it with 0.1N potassium hydroxide-2-propanol solution, and set the end point of neutralization when the light red color of the indicator lasts for 30 seconds. The value obtained from this result using the following equation (1) was taken as the acid value of the sample.

Acid value (mgKOH/g)=[cKOH×(V1-V0)×5.611]/S (1) In the formula (1), cKOH is the molar concentration (mol/L) of the 0.1N potassium hydroxide-2-propanol solution, and V1 is the molar concentration of the 0.1mol/L potassium hydroxide-2-propanol solution required for the titration of the sample. The amount (mL), V0 is the amount of 0.1mol/L potassium hydroxide-2-propanol solution required for the titration of the blank test (mL), and S is the collection amount of the sample (g).

＜Gel fraction＞ Cut the adhesive layer into 100mm×60mm and prepare a semi-hardened sample for measurement.

The adhesive layer was cut into 100 mm × 60 mm, and the first peeling sheet side of the self-weighted separator film was irradiated with ultraviolet rays so that the accumulated light intensity would be 3000 mJ/cm ² to prepare a post-cured measurement sample.

Collect about 0.1g of the adhesive sheet of each measurement sample in a sample bottle, add 30ml of ethyl acetate, and shake for 24 hours. Then, the contents of the sample bottle were filtered out using a 150-mesh stainless steel wire mesh, the residue on the wire mesh was dried at 100° C. for 1 hour, and the dry mass (g) was measured. Using the following formula 1, the gel fraction was calculated from the obtained dry mass. Gel fraction (mass %) = (dry mass/collected mass of adhesive sheet) × 100...Equation 1

＜Probe viscosity value＞ Peel off the second peeling sheet of the light release film from the adhesive sheet and attach it to the PET film to prepare a sample for measurement in a semi-hardened state.

Peel off the second release sheet of the light release film from the other adhesive sheet and attach it to the PET film. Next, the first peeling sheet side of the self-weighted separator film was irradiated with ultraviolet rays so that the accumulated light amount would be 3000 mJ/cm ² , and a post-cured measurement sample was produced.

Each measurement sample was cut into 3 cm × 3 cm, and measured under the following conditions using a probe viscosity testing machine. The measurement temperature was set to 23°C and relative humidity 50%. Measuring machine: NS probe viscosity testing machine (manufactured by NICHIBAN Co., Ltd.) Probe diameter: 5mmφ Probe base material: Stainless steel surface finishing AA#400 grinding mirror Scale weight: 19.6g (made of brass) Probe moving speed: 1.0cm/second Dwell time: 1 second

<Elongation at break> The elongation at break was measured in accordance with JIS K 7161-1. At this time, the stretching speed was set to 10 mm/min, and the measurement was performed in an environment of 23° C. and 50% relative humidity. Moreover, the following was used for the measurement sample: the adhesive layer with a thickness of 25 micrometers, a width of 60 mm, and a length of 200 mm was rounded in the longitudinal direction, and processed into the cylindrical shape with a cross-sectional area of 5 mm ^<2> and a height of 60 mm. Place the sample so that the distance between the chucks is 30 mm and stretch it. The elongation when the sample has broken is defined as the elongation at break. In addition, AUTOGRAPH AGS-X manufactured by Shimadzu Corporation was used as the measuring machine.

＜Processability＞ First, the second peeling sheet of the light release film of the adhesive layer was peeled off and bonded to a PET film with a thickness of 25 μm.

Next, peel off the first release sheet of the heavy isolation film and attach it to the PC board. The sample with the structure of PET/adhesive layer/PC board was subjected to autoclave treatment (40°C, 0.5MPa, 30min), and then irradiated with ultraviolet rays from the PET film side in such a way that the accumulated light intensity reached 3000mJ/ ^cm2 . Test specimen. Then, use a cutting machine to cut the end of the test sample, and rub the cut end with your hands from the side of the PC board by peeling off the PET film. The peeling distance at this time was measured to evaluate the workability. The evaluation criteria are as follows, A and B are passed (permissible range), and C is failed. A: The peeling distance is less than 0.05mm B: The peeling distance is more than 0.05mm and less than 0.1mm C: The peeling distance is more than 0.1mm

<Constant load peeling distance> Peel off the light peeling separator of the second peeling sheet, and use a hand ink roller to laminate a cellulose triacetate film (manufactured by FUJIFILM, FUJITAC TD60UL, thickness 60 μm) to replace the peeled off Separator to create a laminated film. The laminated film was cut into a size of 25 mm in width and 100 mm in length, and the first release sheet was peeled off. Next, use a 2kg crimping roller to stick an area of 25mm width and 75mm length on the exposed adhesive surface of 25mm width and 100mm length to the adherend (polycarbonate plate with hard coating: manufactured by Mitsubishi Gas Chemical Co., Ltd., IUPILON The hard-coated side of MR58 (thickness: 1mm). In this state, it was kept in an autoclave at 40°C and 5 atmospheres for 30 minutes to adhere closely to the PC board, and then ultraviolet rays were irradiated from the cellulose triacetate film side in such a way that the cumulative light intensity reached 3000mJ/ ^cm2 . A test piece was produced.

Then, the test piece was placed at i) 85°C, relative humidity 85% and ii) 85°C, relative humidity less than 10% for 24 hours respectively, and then placed at i) 85°C, relative humidity 85% and ii) 85 ℃ and relative humidity less than 10%, hang a 100g weight 34 on the lengthwise end of the non-laminated area (width 25mm, length 25mm) of the laminated film as shown in Figure 4, relative to the adherend. Apply a load of 100g to the flat surface of 32 in the direction of 90°, and leave it in this state for another 5 minutes. The length L (peel distance under constant load) of the point where the laminated film has been peeled off was measured respectively. The evaluation criteria are as follows, A and B are passed (permissible range), and C is failed. A: Peeling cannot be confirmed, or peeling of less than 1mm is observed B: Peeling of 1 mm or more and 50 mm or less is observed C: Peeling greater than 50mm is observed

＜Durability＞ The second release sheet of the light release film of the adhesive layer was peeled off and attached to a cellulose triacetate film (FUJIFILM, FUJITAC TD60UL, thickness 60 μm).

Next, peel off the first release sheet of the heavy isolation film and attach it to the PC board (polycarbonate board with hard coating: IUPILON MR58, thickness 1 mm, manufactured by Mitsubishi Gas Chemical Co., Ltd.). The sample with the structure of cellulose triacetate film/adhesive layer/PC was subjected to autoclave treatment (40°C, 0.5MPa, 30min), and then, the accumulated light intensity was 3000mJ/ ^cm2 , and the sample was removed from the cellulose triacetate film. Side-irradiate ultraviolet light to prepare a test sample of 100mm×200mm size. Then, the test samples were left to stand for 240 hours respectively in the environments of i) 85°C and relative humidity of 85% and ii) 85°C and relative humidity of less than 10%. Then, observe the test sample and observe whether floating and peeling occur. In addition, the judgment of i) condition shows high temperature and high humidity durability, and the judgment of ii) condition shows high temperature durability. The evaluation criteria are as follows, a represents passing (permissible range), and b represents failing. a: Floating and peeling of more than 1.0 mm was not observed b: Floating and/or peeling of more than 1.0 mm was observed

[Table 1]

As can be seen from Table 1 above, the adhesive sheet of the embodiment can exhibit excellent substrate adhesion and durability not only under high temperature conditions but also under high temperature and high humidity conditions. In addition, the adhesive sheet of the Example does not become sticky at the end surface and has good processability. On the other hand, the adhesive sheet of the comparative example has poor base material adhesion, durability or processability under high temperature conditions and high temperature and high humidity conditions.

1,21:Adhesive sheet 11: Adhesive layer 12a: Transparent substrate or peel-off sheet 12b: Peel off the sheet 20: Laminated body 22:Substrate 24: Optical components 27a, 27b, 27c, 27d: drop part 30: Cellulose triacetate membrane 32: Adhered body 34:Weighing hammer L: Length (fixed load peeling distance)

Figure 1 is a schematic cross-sectional view showing the adhesive sheet of the present invention with a release sheet or substrate. FIG. 2 is a schematic cross-sectional view showing an example of the laminated body of the present invention. FIG. 3 is a schematic cross-sectional view showing another example of the laminated body of the present invention. Fig. 4 is a diagram illustrating a method for measuring the peeling distance under a constant load in the present invention.

1: Adhesive sheet

11: Adhesive layer

12a: Transparent substrate or peel-off sheet

12b: Peel off the sheet

Claims (8)

An adhesive sheet having an adhesive layer in which an adhesive composition is in a semi-hardened state. The adhesive composition contains a cross-linked acrylic copolymer A with an acid component, a cross-linking agent B, and two The above multifunctional monomer C with reactive double bonds, the monofunctional monomer D having one reactive double bond in the molecule and the photopolymerization initiator E, the glass transition temperature (Tg) of the aforementioned crosslinked acrylic copolymer A It is -40°C or above, the aforementioned multifunctional monomer C has a bisphenol skeleton in one molecule, and the aforementioned adhesive layer has hardening properties after being hardened by irradiation with active energy rays. When the accumulated light amount is 3000mJ/ ^cm2 , When the aforementioned adhesive layer is irradiated with active energy rays and then hardened, the aforementioned adhesive layer satisfies the following physical properties (1) and (2); Physical property (1): The elongation at break measured in a tensile test with a tensile speed of 10 mm/min is less than 500%; Physical properties (2): The peeling distance of each constant load is less than 50mm when measured using the following measurement conditions: i) 85°C, relative humidity 85% and ii) 85°C, relative humidity less than 10%: (Measurement conditions ) The area of 25mm width and 75mm length of the adhesive surface of the adhesive layer with a width of 25mm and a length of 100mm is attached to the adherend and then hardened; at i) 85℃, relative humidity 85% and ii) 85℃ . In any environment with a relative humidity less than 10%, fix the adherend in the horizontal direction by hanging the non-fitting area of the adhesive layer downwards; apply 100g to the lengthwise end of the non-fitting area of the adhesive layer. Load for 5 minutes, and measure the peeling distance of the bonding area of the adhesive layer from the adherend during the period, as the peeling distance under a certain load at i) 85°C, relative humidity 85% and ii) 85°C, relative humidity less than 10% distance. The adhesive sheet of claim 1, wherein the content of the monofunctional monomer D is 10 to 40 parts by mass relative to 100 parts by mass of the crosslinkable acrylic copolymer A. Such as the adhesive sheet of claim 1 or 2, wherein the content of the aforementioned multifunctional monomer C is 10 to 40 parts by mass relative to 100 parts by mass of the aforementioned crosslinkable acrylic copolymer A. The adhesive sheet according to claim 1 or 2, wherein the acid value of the cross-linked acrylic copolymer A is 1 mgKOH/g or more. The adhesive sheet of claim 1 or 2, wherein the difference between the gel fraction of the adhesive layer in the semi-hardened state and the gel fraction after post-hardening is more than 15%. An adhesive sheet with a release sheet, which has a pair of release sheets with mutually different release forces on both sides of the adhesive sheet according to any one of claims 1 to 5. A laminate having the adhesive sheet according to any one of claims 1 to 5 and an adherend provided on at least one side of the adhesive sheet, wherein the adhesive layer of the adhesive sheet is irradiated with active energy rays. hardening. A method for manufacturing a laminated body, which sequentially includes: step 1, layering an adhered volume on at least one side of the adhesive sheet according to any one of claims 1 to 5; and step 2, by layering the adhesive sheet The adhesive layer is irradiated with active energy rays to harden the adhesive layer.