WO2020262048A1

WO2020262048A1 - Adhesive sheet and method for producing adhesive sheet-attached article

Info

Publication number: WO2020262048A1
Application number: PCT/JP2020/023279
Authority: WO
Inventors: 武史仲野
Original assignee: 日東電工株式会社
Priority date: 2019-06-27
Filing date: 2020-06-12
Publication date: 2020-12-30
Also published as: KR20220024129A; CN114026192A

Abstract

An adhesive sheet (X) according to the present invention comprises an adhesive layer (20). The visible light transmittance at the wavelength of 550 nm of the adhesive layer (20) is able to be decreased by means of a first external stimulus; and the adhesive power of the adhesive layer (20) is able to be increased by means of a second external stimulus. A method for producing an adhesive sheet-attached article according to the present invention comprises: a step wherein an adhesive sheet (X) is bonded to an adherend by means of an adhesive layer (20) of the adhesive sheet (X); a coloring step wherein a first external stimulus is applied to the adhesive layer (20) on the adherend; and an adhesive power increasing step wherein a second external stimulus is applied to the adhesive layer (20) on the adherend before or after the coloring step.

Description

Manufacturing method of adhesive sheet and adhesive sheet attached product

The present invention relates to an adhesive sheet and a method for manufacturing an adhesive sheet-attached product.

An adhesive sheet for reinforcement may be attached to the surface of various devices such as optical devices and electronic devices from the viewpoint of surface protection and impact resistance. The reinforcing pressure-sensitive adhesive sheet has, for example, a laminated structure of a base film and a pressure-sensitive adhesive layer. A technique relating to such a reinforcing adhesive sheet is described in, for example, Patent Document 1 below.

JP-A-2017-132871

The reinforcing adhesive sheet may be required to be transparent so that it can be inspected for foreign matter or air bubbles between the sheet and its adherend surface after being bonded to a predetermined surface.

In addition, the reinforcing adhesive sheet may be required to have reworkability related to the bonding work. Specifically, when the reinforcing adhesive sheet is attached to a predetermined surface, the bonding is poor (that is, the position of the reinforcing adhesive sheet is displaced on the adherend surface, or the adhesive sheet for reinforcement is between the adherend surface and the reinforcing adhesive sheet. The reinforcing adhesive sheet has light peelability to properly peel off from the adherend surface so that it can be attached with an alternative reinforcing adhesive sheet in the event of foreign matter or air bubbles mixed in. May be required.

On the other hand, the reinforcing adhesive sheet that continues to be adhered to the surface of the product device is also required to show sufficient adhesive reliability to the adherend surface as a device structural material. There is a trade-off between such adhesive reliability of the reinforcing adhesive sheet and the above-mentioned light peelability.

In addition, the reinforcing adhesive sheet that continues to be attached to the surface of the product device may be required to have low transparency depending on the properties of the adhered surface. For example, from the viewpoint of design such as the appearance quality of the product device, the color and texture of the adherend surface to which the reinforcing adhesive sheet is attached, these differences within the adherend surface, etc. are transmitted through the adhesive sheet. May be required for the reinforcing adhesive sheet to be difficult to see. For example, when the adherend surface to which the reinforcing adhesive sheet is attached is a highly mirror-like surface such as a metal surface, it may have a light-shielding property for preventing / suppressing external light reflection on such a surface. , May be required for reinforcing adhesive sheets. There is a trade-off between such low transparency of the reinforcing adhesive sheet and the above-mentioned transparency.

The present invention is suitable for ensuring ease of inspection and reworkability regarding bonding to a bonded surface, and also for achieving high adhesive reliability and low transparency on the bonded surface. Provide a suitable, adhesive sheet. The present invention also provides a method for manufacturing an adhesive sheet-attached product using such an adhesive sheet.

According to the first aspect of the present invention, an adhesive sheet is provided. This pressure-sensitive adhesive sheet has a pressure-sensitive adhesive layer. In the pressure-sensitive adhesive layer, the visible light transmittance at a wavelength of 550 nm can be reduced by the first external stimulus, and the adhesive strength can be increased by the second external stimulus. The first external stimulus is, for example, irradiation with active energy rays or heating. The second external stimulus is a different type of stimulus from the first external stimulus, for example, heating or irradiation with active energy rays. Further, the pressure-sensitive adhesive sheet may have a transparent base material laminated on the pressure-sensitive adhesive layer. In the pressure-sensitive adhesive sheet of the present invention, a first external stimulus is applied to the pressure-sensitive adhesive layer to reduce the visible light transmittance of the same layer, and then a second external stimulus is applied to the pressure-sensitive adhesive layer. It is possible to increase the adhesive strength of the same layer. Alternatively, a second external stimulus is applied to the pressure-sensitive adhesive layer to increase the adhesive strength of the same layer, and then a first external stimulus is applied to the pressure-sensitive adhesive layer to increase the visible light transmittance of the same layer. It is also possible to reduce it.

As described above, the pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet of the present invention can reduce the visible light transmittance at a wavelength of 550 nm due to the first external stimulus (the wavelength of 550 nm is within the intermediate region in the wavelength range of visible light). Therefore, the transmittance of light having a wavelength of 550 nm in the pressure-sensitive adhesive layer tends to affect the color of the pressure-sensitive adhesive layer and the transparency in the visible light region). Such a configuration is suitable for properly using a state in which the transparency in the visible light region is relatively high and a state in which the transparency is relatively low in the pressure-sensitive adhesive sheet. For example, after the adhesive sheet of the present invention is attached to a predetermined surface, the presence or absence of foreign matter or air bubbles between the sheet and the adherend surface is inspected in a state where the sheet has relatively high transparency, and the inspection is performed. After passing, it is possible to apply a first external stimulus to the pressure-sensitive adhesive layer of the sheet to change the transparency of the sheet to a relatively low state. The lower the transparency of the adhesive sheet attached to the adherend surface, the more difficult it is to see the color and texture of the adherend surface, these differences within the adherend surface, and the more the adherend surface reflects external light. The reflection of external light is suppressed even on the surface where the above is likely to occur.

As described above, the pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet of the present invention can increase its adhesive strength due to the second external stimulus. In such a configuration, in the adhesive sheet or its adhesive layer, a state in which the adhesive force to the adherend is relatively low (low adhesive force state) and a state in which the adhesive force is relatively high (high adhesive force state) are used properly. Suitable. For example, when a defect occurs in the adhesion of the adhesive sheet to a predetermined surface, the sheet is attached from the adherend surface in a state where the adhesive force of the adhesive layer of the adhesive sheet having the defective adhesion is relatively low. It can be peeled off. On the other hand, with respect to the pressure-sensitive adhesive sheet appropriately bonded to a predetermined surface, it is possible to give a second external stimulus to the pressure-sensitive adhesive layer to change the adhesive strength of the same layer to a relatively high state. .. The higher the adhesive strength of the adhesive sheet or the pressure-sensitive adhesive layer attached to the adherend surface to the adherend surface, the easier it is to realize high adhesive reliability with respect to the adherend surface in the adhesive sheet.

As described above, the adhesive sheet according to the first aspect of the present invention is suitable for ensuring ease of inspection and reworkability with respect to bonding to the bonded surface, and is on the bonded surface. Suitable for achieving high adhesive reliability and low transparency. Such an adhesive sheet of the present invention can be suitably used as a reinforcing adhesive sheet to be attached to the surface of various devices such as optical devices and electronic devices.

The first external stimulus is preferably activation energy ray irradiation. Such a configuration is preferable from the viewpoint of ease of control regarding a decrease in the visible light transmittance of the pressure-sensitive adhesive layer due to the first external stimulus. Further, such a configuration is suitable for forming a pattern of a visible light transmittance lowering region in the pressure-sensitive adhesive layer.

The second external stimulus is preferably heating. Such a configuration is suitable for adopting active energy ray irradiation (a different type from the second external stimulus) as the first external stimulus.

Regarding the pressure-sensitive adhesive sheet of the present invention, stainless steel has a resistance to the first adhesive force shown on the stainless steel plate in a peeling test under peeling conditions of 23 ° C., a peeling angle of 180 ° and a peeling speed of 300 mm / min after being bonded to the stainless steel plate. After bonding to the plate and irradiating with ultraviolet rays under irradiation conditions of an irradiation wavelength of 365 nm and an irradiation light amount of 4000 mJ / cm ² , the ratio of the second adhesive force shown to the stainless steel plate in the peeling test under the above peeling conditions is , Preferably 2 or less. In this configuration, in the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet, the rate of increase in adhesive strength to the adherend due to receiving the first external stimulus is suppressed, and the rate of increase in adhesive strength to the adherend due to receiving the second external stimulus is suppressed. Suitable for securing.

Regarding the pressure-sensitive adhesive sheet of the present invention, stainless steel has a resistance to the first adhesive force shown on the stainless steel plate in a peeling test under peeling conditions of 23 ° C., a peeling angle of 180 ° and a peeling speed of 300 mm / min after being bonded to the stainless steel plate. After bonding to the plate, irradiating with ultraviolet rays under irradiation conditions of an irradiation wavelength of 365 nm and an irradiation amount of 4000 mJ / cm ² , and heating at 80 ° C. for 5 minutes, the stainless steel plate was subjected to a peeling test under the above peeling conditions. The ratio of the third adhesive force shown to the above is preferably 5 or more. The third adhesive strength is preferably 5N / 25mm or more. These configurations are suitable for ensuring high adhesive reliability with respect to the adherend surface in the adhesive sheet attached to the adherend surface.

The visible light transmittance at a wavelength of 550 nm before the pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet receives the first external stimulus is preferably 85% or more. Such a configuration is suitable for inspecting the presence or absence of foreign matter or air bubbles between the sheet and its adherend surface after the adhesive sheet is attached to a predetermined surface.

The visible light transmittance at a wavelength of 550 nm after the pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet receives the first external stimulus is preferably 80% or less. Such a configuration is suitable for making it difficult to visually recognize the adherend surface to which the adhesive sheet is attached, and is also suitable for preventing / suppressing the above-mentioned external light reflection on the adherend surface.

The visible average light transmittance at a wavelength of 300 to 700 nm before the pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet receives the first external stimulus is preferably 83% or more. Such a configuration is suitable for inspecting the presence or absence of foreign matter or air bubbles between the sheet and its adherend surface after the adhesive sheet is attached to a predetermined surface.

The visible average light transmittance at a wavelength of 300 to 700 nm after the pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet receives the first external stimulus is preferably 75% or less. Such a configuration is suitable for making it difficult to visually recognize the adherend surface to which the adhesive sheet is attached, and is also suitable for preventing / suppressing the above-mentioned external light reflection on the adherend surface.

The haze of the adhesive sheet before receiving the first external stimulus is preferably 3% or less. Such a configuration is suitable for inspecting the presence or absence of foreign matter or air bubbles between the sheet and its adherend surface after the adhesive sheet is attached to a predetermined surface.

The pressure-sensitive adhesive layer preferably comprises a pressure-sensitive composition containing a compound that develops color by reaction with an acid (color-developing compound) and an acid generator. This configuration is suitable for realizing a decrease in the visible light transmittance of the pressure-sensitive adhesive layer due to the first external stimulus.

The pressure-sensitive adhesive layer preferably comprises a pressure-sensitive composition containing a base polymer and an organosiloxane structure-containing polymer. The base polymer in the pressure-sensitive adhesive layer means a polymer component that occupies the largest mass ratio of the polymer components in the pressure-sensitive adhesive layer. The organosiloxane structure-containing polymer refers to a polymer having an organosiloxane structure as, for example, a side chain.

Such a configuration is suitable for changing the pressure-sensitive adhesive layer from a low adhesive strength state to a high adhesive strength state due to the heating when heating is adopted as the second external stimulus.

The base polymer is preferably an acrylic polymer. The acrylic polymer is suitable for ensuring high transparency in the pressure-sensitive adhesive layer before receiving the first external stimulus. The acrylic polymer is also preferable from the viewpoint of easy control of the adhesive force in the pressure-sensitive adhesive layer.

The glass transition temperature of the acrylic polymer is preferably 0 ° C. or lower. Such a configuration is suitable for ensuring the fluidity of the acrylic polymer in the pressure-sensitive adhesive layer, and therefore, when heating is adopted as the second external stimulus, the pressure-sensitive adhesive layer has a high adhesive strength due to the heating. Suitable for changing to a state.

The organosiloxane structure-containing polymer is preferably a monomer component containing a first monomer having an organosiloxane skeleton and a second monomer copolymerizable with the first monomer having a homopolymer glass transition temperature of 40 ° C. or higher. It is a polymer. Such a configuration is suitable for adjusting the adhesive force in the pressure-sensitive adhesive layer 20, ensuring the rate of increase in the adhesive force by heating, and ensuring the compatibility between the base polymer and the organosiloxane structure-containing polymer.

According to the second aspect of the present invention, a method for manufacturing an adhesive sheet-attached product is provided. This manufacturing method includes a bonding step, a coloring step, and an adhesive strength increasing step. In the bonding step, the pressure-sensitive adhesive sheet according to the first aspect of the present invention is bonded to the adherend with the pressure-sensitive adhesive layer. In the coloring step, a first external stimulus is applied to the pressure-sensitive adhesive layer on the adherend. As a result, the visible light transmittance at a wavelength of 550 nm is reduced in the pressure-sensitive adhesive layer, and therefore the visible light transmittance of the pressure-sensitive adhesive sheet is reduced. In the adhesive force increasing step, a second external stimulus is applied to the adhesive layer on the adherend. As a result, the adhesive strength of the pressure-sensitive adhesive layer to the adherend is increased. The adhesive strength increasing step is performed before or after the coloring step.

In the present manufacturing method in which the above-mentioned pressure-sensitive adhesive sheet according to the first aspect of the present invention is used, in the manufacturing process of the pressure-sensitive adhesive sheet-attached product, an inspection is performed regarding the bonding of the pressure-sensitive adhesive sheet to the adherend surface (attached surface). It is suitable for ensuring ease of use and reworkability, and also suitable for achieving high adhesive reliability and low transparency in an adhesive sheet attached to an adherend surface. Specifically, it is as follows.

In this manufacturing method, in a state where the transparency of the adhesive sheet is relatively high after the bonding step and before the coloring step and the adhesive strength increasing step, foreign matter or air bubbles between the sheet and the adherend surface. It is possible to inspect for the presence or absence of. As a result of the inspection, when it is necessary to redo the adhesive sheet bonding work, it is possible to peel off the adhesive sheet having a relatively low adhesive force from the adherend surface before the coloring step and the adhesive force increasing step. After that, another adhesive sheet can be attached. Then, in one aspect (first aspect) of the present manufacturing method, the transparency of the pressure-sensitive adhesive layer can be lowered by undergoing a coloring step on the pressure-sensitive adhesive sheet that has undergone an appropriate bonding operation, and then the pressure-sensitive adhesive layer is adhered. By going through the force increasing step, it is possible to increase the adhesive force of the pressure-sensitive adhesive layer and secure high adhesive reliability with respect to the adherend surface. In another aspect (second aspect) of the present manufacturing method, the adhesive force of the adhesive layer is increased by undergoing an adhesive force increasing step for the adhesive sheet that has undergone an appropriate bonding operation, so that the adhesive sheet adheres to the adherend surface. It is possible to secure high adhesive reliability of the agent layer, and then it is possible to reduce the transparency of the pressure-sensitive adhesive layer by undergoing a coloring step.

In the present production method, preferably, the first external stimulus is irradiation with active energy rays. Such a configuration is suitable for patterning a region where the visible light transmittance is lowered in the pressure-sensitive adhesive layer. According to the configuration, by irradiating the pressure-sensitive adhesive layer with active energy rays through a mask pattern for masking a predetermined area in the pressure-sensitive adhesive layer, the region of the pressure-sensitive adhesive layer that is not masked by the mask pattern It is possible to reduce the visible light transmittance and color it (pattern formation of a colored region). Further, according to the first aspect of the present manufacturing method, even if the colored region formed in the pattern on the adhesive layer is displaced, the adhesive strength is relatively low before the adhesive strength increasing step. The adhesive sheet in the above can be peeled off from the adherend surface, and then the adhesive sheet bonding work can be reworked.

In the present production method, the second external stimulus is preferably heating. Such a configuration is suitable for adopting active energy ray irradiation (a different type from the second external stimulus) as the first external stimulus.

It is sectional drawing of the adhesive sheet which concerns on one Embodiment of this invention. FIG. 2A shows a part of the steps in the method for manufacturing an adhesive sheet-attached product according to an embodiment of the present invention, FIG. 2B shows a step after the step shown in FIG. 2A, and FIG. 2C shows FIG. 2B. Represents a process after the process shown. In the method for manufacturing an adhesive sheet-attached product shown in FIG. 2, a case where a colored region is patterned in the coloring step is shown.

FIG. 1 is a schematic cross-sectional view of the pressure-sensitive adhesive sheet X according to the embodiment of the present invention. The pressure-sensitive adhesive sheet X includes a base material 10 and a pressure-sensitive adhesive layer 20, and has a laminated structure including these. The base material 10 and the pressure-sensitive adhesive layer 20 may be directly bonded or may be bonded via another layer. Specifically, the pressure-sensitive adhesive sheet X includes a base material 10 and an adhesive layer 20 arranged on one side thereof, and is preferably a pressure-sensitive adhesive arranged so as to be in contact with the base material 10 on one side thereof. The agent layer 20 is provided.

The base material 10 is an element that functions as a transparent support in the adhesive sheet X. The base material 10 is, for example, a flexible plastic film. Examples of the constituent material of the plastic film include polyolefin, polyester, polyamide, polyimide, polyvinyl chloride, polyvinylidene chloride, cellulose, polystyrene, and polycarbonate. Examples of the polyolefin include polyethylene, polypropylene, poly-1-butene, poly-4-methyl-1-pentene, ethylene / propylene copolymer, ethylene / 1-butene copolymer, ethylene / vinyl acetate copolymer, and the like. Examples thereof include polyethylene / ethyl acrylate copolymers and ethylene / vinyl alcohol copolymers. Examples of polyesters include polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate. Examples of the polyamide include nylon 6, nylon 6,6, and partially aromatic polyamide. The base material 10 may be made of one kind of material, or may be made of two or more kinds of materials. The base material 10 may have a single-layer structure or a multi-layer structure. The base material 10 may be a non-stretched film, a uniaxially stretched film, or a biaxially stretched film. From the viewpoint of achieving both transparency and mechanical strength of the base material 10, the plastic material for constructing the base material 10 is preferably polyester, more preferably polyethylene terephthalate.

The base material 10 has transparency. The haze of the base material 10 is preferably 20% or less, more preferably 10% or less, more preferably 5% or less, and even more preferably 3% or less. The haze value is measured by a haze meter (“NDH2000” manufactured by Nippon Denshoku Kogyo Co., Ltd. or “HM-150 type” manufactured by Murakami Color Technology Research Institute) in accordance with JIS K7136 (2000).

The surface 11 on the pressure-sensitive adhesive layer 20 side of the base material 10 may be subjected to a physical treatment, a chemical treatment, or an undercoating treatment for enhancing the adhesion to the pressure-sensitive adhesive layer 20. Physical treatments include, for example, corona treatment and plasma treatment. Examples of the chemical treatment include acid treatment and alkali treatment.

The thickness of the base material 10 is preferably 5 μm or more, more preferably 10 μm or more, and more preferably 20 μm or more from the viewpoint of ensuring the strength for the base material 10 to function as a support. Further, from the viewpoint of realizing appropriate flexibility in the pressure-sensitive adhesive sheet X, the thickness of the base material 10 is preferably 200 μm or less, more preferably 150 μm or less, and more preferably 100 μm or less.

The pressure-sensitive adhesive layer 20 in the pressure-sensitive adhesive sheet X is an element for attaching the pressure-sensitive adhesive sheet X to an adherend, and has an adhesive surface 21 on the side opposite to the base material 10. The pressure-sensitive adhesive layer 20 can be colored by the first external stimulus, and the adhesive strength can be increased by the second external stimulus. Specifically, the pressure-sensitive adhesive layer 20 can change from a state in which the visible light transmittance at a wavelength of 550 nm is relatively high to a state in which it is relatively low due to the first external stimulus, and the second. The adhesive strength of the adhesive surface 21 can be changed from a relatively low state (low adhesive strength state) to a relatively high adhesive strength state (high adhesive strength state) due to an external stimulus.

In the unused adhesive sheet X, the adhesive layer 20 is in a state where the visible light transmittance at a wavelength of 550 nm is relatively high and is in a low adhesive force state. In such a pressure-sensitive adhesive sheet X, a first external stimulus is applied to the pressure-sensitive adhesive layer 20 to reduce the visible light transmittance of the same layer, and then a second external stimulus is applied to the pressure-sensitive adhesive layer 20. It is possible to increase the adhesive strength of the same layer. Alternatively, a second external stimulus is applied to the pressure-sensitive adhesive layer 20 to increase the adhesive strength of the same layer, and then a first external stimulus is applied to the pressure-sensitive adhesive layer 20 to increase the visible light transmittance of the same layer. It is also possible to reduce.

Examples of the first external stimulus include irradiation with active energy rays and heating. Examples of the active energy ray include ultraviolet rays and electron beams. The second external stimulus is a different type of stimulus from the first external stimulus, and examples thereof include heating and irradiation with active energy rays. The pressure-sensitive adhesive layer 20 is a pressure-sensitive adhesive layer (first type pressure-sensitive adhesive layer) in which the visible light transmittance at a wavelength of 550 nm can be reduced by irradiation with active energy rays and the adhesive strength can be increased by heating. A pressure-sensitive adhesive layer (second type pressure-sensitive adhesive layer) in which the visible light transmittance at a wavelength of 550 nm can be reduced by heating and the adhesive strength can be increased by irradiation with active energy rays. ) May be.

When the pressure-sensitive adhesive layer 20 is a first-type pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer 20 contains a base polymer, an organosiloxane structure-containing polymer, a compound that develops color by reaction with an acid (color-developing compound), and a photoacid. It comprises a first sticky composition containing a generator. Due to its low polarity, the organosiloxane structure portion of the organosiloxane structure-containing polymer tends to be unevenly distributed on the adhesive surface 21 (the surface to be adhered to the adherend) in the initial state of the adhesive layer 20. Has (low adhesive strength state of the adhesive layer 20). When the pressure-sensitive adhesive layer 20 is heated, the fluidity and compatibility of the base polymer and the organosiloxane structure-containing polymer in the pressure-sensitive adhesive layer 20 tend to increase, and therefore, the organosiloxane of the organosiloxane structure-containing polymer tends to increase. Structural parts are more likely to diffuse heat. Then, in the adhesive surface 21 and its vicinity, the polyorganosiloxane structural parts that had been unevenly distributed there are thermally diffused, and the abundance ratio of the base polymer on the adhesive surface 21 increases, so that the adhesive surface 21 is adhered. The force increases (ie, the pressure-sensitive adhesive layer 20 reaches a high pressure-sensitive state). Further, the pressure-sensitive adhesive layer 20 is colored by the reaction between the color-developing compound and the acid derived from the photoacid generator.

The base polymer occupies the largest mass ratio of the polymer components in the pressure-sensitive adhesive layer 20. Examples of such base polymers include acrylic polymers, rubber-based polymers, polyester-based polymers, urethane-based polymers, polyether-based polymers, silicone-based polymers, polyamide-based polymers, and fluorine-based polymers, which have rubber elasticity in the room temperature range. Examples include the polymers shown. From the viewpoint of easy control of the adhesive force in the pressure-sensitive adhesive layer 20, an acrylic polymer is preferable as the base polymer. The first sticky composition may contain other polymers as well as the base polymer. Further, the content ratio of the base polymer in the first adhesive composition is preferably 50% by mass or more, more preferably 60% by mass or more, and more, from the viewpoint of appropriately expressing the function of the base polymer in the pressure-sensitive adhesive layer 20. It is preferably 70% by mass or more.

The acrylic polymer is, for example, a polymer obtained by polymerizing a monomer component (first monomer component) containing (meth) acrylic acid alkyl ester in a proportion of 50% by mass or more (specifically, (meth) acrylic acid alkyl). A polymer containing a unit derived from an ester in a proportion of 50% by mass or more). "(Meta) acrylic acid" shall mean acrylic acid and / or methacrylic acid. The proportion of the (meth) acrylic acid alkyl ester in the first monomer component is preferably 60% by mass or more, more preferably 70% by mass or more, from the viewpoint of appropriately expressing basic properties such as tackiness in the pressure-sensitive adhesive layer 20. Is. The same ratio is, for example, 90% by mass or less.

Examples of the (meth) acrylic acid alkyl ester include a (meth) acrylic acid alkyl ester having a linear or branched alkyl group having 1 to 20 carbon atoms. Examples of such (meth) acrylic acid alkyl esters include methyl (meth) acrylic acid, ethyl (meth) acrylic acid, propyl (meth) acrylic acid, n-butyl (meth) acrylic acid, and (meth) acrylic acid. Isopropyl, (meth) butyl acrylate, (meth) isobutyl acrylate, (meth) s-butyl acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, (meth) ) Neopentyl acrylate, (meth) hexyl acrylate, (meth) heptyl acrylate, (meth) 2-ethylhexyl acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, (meth) Isononyl acrylate, (meth) decyl acrylate, (meth) isodecyl acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, isotridodecyl (meth) acrylate, tetradecyl (meth) acrylate, Isotetradecyl (meth) acrylate, pentadecyl acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, isooctadecyl (meth) acrylate, (meth) acrylic acid Nonadesyl and Eikosyl (meth) acrylate can be mentioned. The (meth) acrylic acid ester may be used alone or in combination of two or more.

From the viewpoint of adjusting the glass transition temperature of the acrylic polymer, it is preferable to use an acrylic acid alkyl ester (acrylic acid C _4-12 alkyl ester) having an alkyl group having 4 to 12 carbon atoms in combination with methyl methacrylate. .. In this case, the amount of acrylic acid C _4-12 alkyl ester is preferably 80 parts by mass or more with _respect to 100 parts by mass of the total amount of acrylic acid C _4-12 alkyl ester and methyl methacrylate in the first monomer component. The amount of methyl methacrylate is preferably 5 parts by mass or more, and preferably 20 parts by mass or less.

The first monomer component may contain one or more other monomers (copolymerizable monomers) copolymerizable with the (meth) acrylic acid alkyl ester. From the viewpoint of obtaining the effect of using the copolymerizable monomer, the ratio of the copolymerizable monomer in the first monomer component is preferably 0.1% by mass or more, and more preferably 1% by mass or more. The same ratio is, for example, 50% by mass or less, preferably 40% by mass or less.

Examples of the copolymerizable monomer include a monomer having a polar group. The polar group-containing monomer is useful for modifying the acrylic polymer, such as introducing a cross-linking point into the acrylic polymer and ensuring the cohesive force of the acrylic polymer. Examples of the polar group-containing monomer include a hydroxyl group-containing monomer, a carboxy group-containing monomer, and a monomer having a nitrogen atom-containing ring. The copolymerizable monomer preferably contains at least one selected from the group consisting of a hydroxyl group-containing monomer, a carboxy group-containing monomer, and a monomer having a nitrogen atom-containing ring. More preferably, the copolymerizable monomer comprises a hydroxyl group-containing monomer and / or a carboxy group-containing monomer (that is, the acrylic polymer has a hydroxyl group and / or a carboxy group).

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and (meth). ) 4-Hydroxybutyl acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, and ( 4-Hydroxymethylcyclohexyl) methyl (meth) acrylate can be mentioned. The hydroxyl group-containing monomer is preferably 2-hydroxyethyl (meth) acrylate, and more preferably 2-hydroxyethyl acrylate.

The ratio of the hydroxyl group-containing monomer in the first monomer component is preferably 1% by mass or more, more preferably 3% by mass, from the viewpoint of introducing a crosslinked structure into the acrylic polymer and ensuring the cohesive force in the pressure-sensitive adhesive layer 20. As mentioned above, it is more preferably 5% by mass or more. The same ratio is preferably 30 from the viewpoint of adjusting the viscosity of the polymerization reaction solution during the polymerization of the acrylic polymer and adjusting the polarity of the acrylic polymer, which is related to the compatibility between various additive components in the pressure-sensitive adhesive layer 20 and the acrylic polymer. It is 0% by mass or less, more preferably 20% by mass or less.

Examples of the carboxy group-containing monomer include acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid.

The ratio of the carboxy group-containing monomer in the first monomer component is determined from the viewpoint of introducing a crosslinked structure into the acrylic polymer, ensuring the cohesive force in the pressure-sensitive adhesive layer 20, and ensuring the adhesion to the adherend in the pressure-sensitive adhesive layer 20. Is preferably 1% by mass or more, more preferably 3% by mass or more, and more preferably 5% by mass or more. The same ratio is preferably 30% by mass or less, more preferably 20% by mass or less, from the viewpoint of adjusting the glass transition temperature of the acrylic polymer and avoiding the risk of corrosion of the adherend by acid.

Examples of the monomer having a nitrogen atom-containing ring include N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, and N-vinylpyrazine. N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N- (meth) acryloyl-2-pyrrolidone, N- (meth) acryloyl piperidine, N- (meth) acryloylpyrrolidin, N-vinylmorpholin, N-vinyl -3-morpholinone, N-vinyl-2-caprolactam, N-vinyl-1,3-oxadin-2-one, N-vinyl-3,5-morpholindione, N-vinylpyrazole, N-vinylisoxazole, N -Vinylthiazole and N-vinylisothiazole are mentioned. The monomer having a nitrogen atom-containing ring is preferably N-vinyl-2-pyrrolidone.

The proportion of the monomer having a nitrogen atom-containing ring in the first monomer component is preferably 1 from the viewpoint of ensuring the cohesive force in the pressure-sensitive adhesive layer 20 and the adhesion to the adherend in the pressure-sensitive adhesive layer 20. It is by mass% or more, more preferably 3% by mass or more, and more preferably 5% by mass or more. The same ratio is preferably 30% by mass or less from the viewpoint of adjusting the glass transition temperature of the acrylic polymer and adjusting the polarity of the acrylic polymer, which is related to the compatibility between various additive components in the pressure-sensitive adhesive layer 20 and the acrylic polymer. , More preferably 20% by mass or less.

The first monomer component may contain other copolymerizable monomers. Other copolymerizable monomers include, for example, acid anhydride monomers such as maleic anhydride and itaconic anhydride, sulfonic acid group-containing monomers, phosphate group-containing monomers such as 2-hydroxyethylacryloyl phosphate, and epoxy group-containing monomers. Cyano group-containing monomers such as acrylonitrile and methacrylonitrile, isocyanate group-containing monomers such as 2-isocyanatoethyl (meth) acrylate, amide group-containing monomers, monomers having a succinimide skeleton, maleimides, itaconimides, (meth) acrylic acid. Aminoalkyls, alkoxy group-containing monomers, vinyl esters such as vinyl acetate and vinyl propionate, vinyl ethers, aromatic vinyl compounds, olefins, (meth) acrylic acid esters having alicyclic hydrocarbon groups, and aromatics. Examples thereof include (meth) acrylic acid esters having a group hydrocarbon group.

Examples of the sulfonic acid group-containing monomer include styrene sulfonic acid, allyl sulfonic acid, sodium vinyl sulfonic acid, 2- (meth) acrylamide-2-methylpropane sulfonic acid, (meth) acrylamide propane sulfonic acid, and sulfopropyl (meth). Acrylates and (meth) acryloyloxynaphthalene sulfonic acid can be mentioned.

Examples of the epoxy group-containing monomer include epoxy group-containing acrylates such as glycidyl (meth) acrylate and -2-ethylglycidyl ether (meth) acrylate, allyl glycidyl ether, and glycidyl ether (meth) acrylate.

Examples of the amide group-containing monomer include N-vinylcarboxylic acid amides such as (meth) acrylamide, N, N-dialkyl (meth) acrylamide, N-alkyl (meth) acrylamide, and N-vinylacetamide, and N-hydroxyalkyl. Examples include (meth) acrylamide, N-alkoxyalkyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, and N- (meth) acryloylmorpholine. Examples of N, N-dialkyl (meth) acrylamide include N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N, N-dipropyl (meth) acrylamide, and N, N-diisopropyl. Examples include meta) acrylamide, N, N-di (n-butyl) (meth) acrylamide, and N, N-di (t-butyl) (meth) acrylamide. Examples of N-alkyl (meth) acrylamide include N-ethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-butyl (meth) acrylamide, and N-n-butyl (meth) acrylamide. Examples of N-hydroxyalkyl (meth) acrylamide include N- (2-hydroxyethyl) (meth) acrylamide, N- (2-hydroxypropyl) (meth) acrylamide, and N- (1-hydroxypropyl) (meth). Acrylamide, N- (3-hydroxypropyl) (meth) acrylamide, N- (2-hydroxybutyl) (meth) acrylamide, N- (3-hydroxybutyl) (meth) acrylamide, and N- (4-hydroxybutyl) Examples include (meth) acrylamide. Examples of N-alkoxyalkyl (meth) acrylamide include N-methoxymethyl (meth) acrylamide, N-methoxyethyl (meth) acrylamide, and N-butoxymethyl (meth) acrylamide.

Examples of the monomer having a succinimide skeleton include N- (meth) acryloyloxymethylene succinimide, N- (meth) acryloyl-6-oxyhexamethylene succinimide, and N- (meth) acryloyl-8-oxyhexamethylene succinimide. Be done.

Examples of maleimides include N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, and N-phenylmaleimide.

Examples of the itaconimides include N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, and N-laurylitaconimide can be mentioned.

Examples of aminoalkyl (meth) acrylates include aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, and (meth). Examples thereof include t-butylaminoethyl acrylate.

Examples of the alkoxy group-containing monomer include (meth) acrylate alkoxyalkyls and (meth) acrylate alkoxyalkylene glycols. Examples of the alkoxyalkyl (meth) acrylate include 2-methoxyethyl (meth) acrylate, 3-methoxypropyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, and propoxyethyl (meth) acrylate. , Butoxyethyl (meth) acrylate, and ethoxypropyl (meth) acrylate. Examples of the (meth) acrylate alkoxyalkylene glycols include (meth) methoxyethylene glycol acrylate and methoxypolypropylene glycol (meth) acrylate.

Examples of vinyl ethers include vinyl alkyl ethers such as methyl vinyl ether and ethyl vinyl ether. Aromatic vinyl compounds include, for example, styrene, α-methylstyrene, and vinyltoluene. Examples of olefins include ethylene, butadiene, isoprene, and isobutylene.

Examples of the (meth) acrylic acid ester having an alicyclic hydrocarbon group include cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, and dicyclopentanyl (meth) acrylate.

Examples of the (meth) acrylic acid ester having an aromatic hydrocarbon group include phenyl (meth) acrylate, phenoxyethyl (meth) acrylate, and benzyl (meth) acrylate.

The first monomer component may contain one or more types of polyfunctional monomers for the purpose of adjusting the cohesive force of the pressure-sensitive adhesive layer 20 and the like. Examples of the polyfunctional monomer include ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, and the like. Pentaerythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, ethylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,12-dodecane Didioldi (meth) acrylate, trimethylolpropantri (meth) acrylate, tetramethylolmethanetri (meth) acrylate, allyl (meth) acrylate, vinyl (meth) acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane acrylate, butyl Examples thereof include diol (meth) acrylate and hexyldiol di (meth) acrylate. The proportion of the polyfunctional monomer in the first monomer component is preferably 0.01% by mass or more, more preferably 0.02% by mass or more. The same ratio is preferably 2.0% by mass or less, and more preferably 1.0% by mass or less.

The weight average molecular weight of the acrylic polymer is preferably 100,000 or more, more preferably 300,000 or more, and more preferably 500,000 or more from the viewpoint of ensuring the cohesive force in the pressure-sensitive adhesive layer 20. From the viewpoint of ensuring the fluidity of the acrylic polymer, the weight average molecular weight is preferably 5,000,000 or less, more preferably 3,000,000 or less, and more preferably 2000000 or less. The weight average molecular weight of the acrylic polymer is measured by gel permeation chromatography (GPC) and calculated in terms of polystyrene.

The glass transition temperature (Tg) of the base polymer is preferably 0 ° C. or lower, more preferably -10 ° C. or lower, and more preferably -20 ° C. or lower. The glass transition temperature is, for example, −80 ° C. or higher. Such a configuration is suitable for ensuring the fluidity of the base polymer, and is therefore suitable from the viewpoint of increasing the adhesiveness of the pressure-sensitive adhesive layer 20 by heating.

For the glass transition temperature (Tg) of the polymer, the glass transition temperature (theoretical value) obtained based on the Fox formula below can be used. The Fox formula is a relational expression between the glass transition temperature Tg of the polymer and the glass transition temperature Tgi of the homopolymer of the monomer constituting the polymer. In the Fox formula below, Tg represents the glass transition temperature (° C.) of the polymer, Wi represents the weight fraction of the monomer i constituting the polymer, and Tgi represents the glass transition of the homopolymer formed from the monomer i. Indicates the temperature (° C). Literature values can be used for the glass transition temperature of homopolymers, for example, "Polymer Handbook" (4th edition, John Wiley & Sons, Inc., 1999) and "New Polymer Bunko 7 Introduction to Synthetic Resins for Paints". (Kyozo Kitaoka, Polymer Publications, 1995) lists the glass transition temperatures of various homopolymers. On the other hand, the glass transition temperature of the homopolymer of the monomer can also be obtained by the method specifically described in JP-A-2007-51271.

Fox formula 1 / (273 + Tg) = Σ [Wi / (273 + Tgi)]

The acrylic polymer can be formed by polymerizing the above-mentioned first monomer component. Examples of the polymerization method include solution polymerization, bulk polymerization, and emulsion polymerization, and solution polymerization is preferable. In solution polymerization, for example, the first monomer component and the polymerization initiator are mixed with a solvent to prepare a reaction solution, and then the reaction solution is heated. Then, an acrylic polymer solution containing an acrylic polymer can be obtained by undergoing a polymerization reaction of the first monomer component in the reaction solution. As the polymerization initiator, a thermal polymerization initiator and a photopolymerization initiator can be used depending on the polymerization method. The amount of the polymerization initiator used is, for example, 0.01 to 5 parts by mass, preferably 0.05 to 3 parts by mass with respect to 100 parts by mass of the first monomer component.

Examples of the thermal polymerization initiator include azo-based polymerization initiators, peroxide-based polymerization initiators, and persulfates such as potassium persulfate. Examples of the azo-based polymerization initiator include 2,2'-azobisisobutyronitrile, 2,2'-azobis-2-methylbutyronitrile, and 2,2'-azobis (2-methylpropionic acid) dimethyl. 4,4'-azobis-4-cyanovaleric acid, azobisisobutaleronitrile, 2,2'-azobis (2-amidinopropane) dihydrochloride, 2,2'-azobis [2- (5-methyl-2) -Imidazoline-2-yl) propane] dihydrochloride, 2,2'-azobis (2-methylpropionamidine) disulfate, and 2,2'-azobis (N, N'-dimethyleneisobutyramidine) dihydrochloride Can be mentioned. Peroxide-based polymerization initiators include, for example, dibenzoyl peroxide, t-butyl permalate, and lauroyl peroxide.

Examples of the photopolymerization initiator include a benzoin ether type photopolymerization initiator, an acetophenone type photopolymerization initiator, an α-ketol type photopolymerization initiator, an aromatic sulfonyl chloride type photopolymerization initiator, and a photoactive oxime type photopolymerization initiator. Agents, benzoin-based photopolymerization initiators, benzyl-based photopolymerization initiators, benzophenone-based photopolymerization initiators, ketal-based photopolymerization initiators, thioxanthone-based photopolymerization initiators, and acylphosphine oxide-based photopolymerization initiators. Be done.

The first adhesive composition may contain a cross-linking agent from the viewpoint of introducing a cross-linked structure into the base polymer. Examples of the cross-linking agent for forming a cross-linked structure by reacting with the cross-linking point when the base polymer has a cross-linking point include an isocyanate-based cross-linking agent, an epoxy-based cross-linking agent, an oxazoline-based cross-linking agent, and an aziridine-based cross-linking agent. Examples thereof include a carbodiimide-based cross-linking agent and a metal chelate-based cross-linking agent. The cross-linking agent may be used alone or in combination of two or more.

Examples of the isocyanate-based cross-linking agent include tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, tetramethylxylylene diisocyanate, naphthalin diisocyanate, and triphenylmethane. Examples thereof include triisocyanate and polymethylene polyphenyl isocyanate. In addition, examples of the isocyanate-based cross-linking agent include derivatives of these isocyanates (for example, isocyanurate-modified products and polyol-modified products). Examples of commercially available isocyanate-based cross-linking agents include coronate L (trimethylolpropane adduct of tolylene diisocyanate, manufactured by Tosoh), coronate HL (trimethylolpropane adduct of hexamethylene diisocyanate, manufactured by Tosoh), and coronate HX (). Examples thereof include an isocyanurate form of hexamethylene diisocyanate (manufactured by Tosoh) and Takenate D110N (trimethylolpropane adduct form of xylylene diisocyanate, manufactured by Mitsui Chemicals).

As the epoxy-based cross-linking agent, bisphenol A, epichlorohydrin-type epoxy resin, ethylene glycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol glycidyl ether, trimethyl propantri Examples include glycidyl ether, diglycidyl aniline, diamine glycidyl amine, N, N, N', N'-tetraglycidyl-m-xylylene diamine, and 1,3-bis (N, N-diglycidyl aminomethyl) cyclohexane. .. Examples of commercially available epoxy-based cross-linking agents include tetrad C (1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, manufactured by Mitsubishi Gas Chemical Company, Inc.).

From the viewpoint of ensuring the cohesive force of the pressure-sensitive adhesive layer 20, the amount of the cross-linking agent used is, for example, 0.01 part by mass or more, preferably 0.05 part by mass or more, based on 100 parts by mass of the base polymer. It is preferably 0.1 parts by mass or more. From the viewpoint of ensuring good tackiness in the pressure-sensitive adhesive layer 20, the amount of the cross-linking agent used with respect to 100 parts by mass of the base polymer is, for example, 10 parts by mass or less, preferably 5 parts by mass or less, and more preferably 3 parts by mass. It is as follows.

When a crosslinked structure is introduced into the base polymer, a crosslinked catalyst may be used to effectively promote the crosslinking reaction. Examples of the cross-linking catalyst include metal-based cross-linking catalysts such as tetra-n-butyl titanate, tetraisopropyl titanate, ferric nasem, butyl tin oxide, and dioctyl tin dilaurate. The amount of the cross-linking catalyst used is, for example, 0.0001 to 1 part by mass with respect to 100 parts by mass of the base polymer.

Examples of the organosiloxane structure-containing polymer include acrylic-based, urethane-based, polyether-based, polyester-based, polycarbonate-based, and polybutadiene-based polymers having an organosiloxane structure. The organosiloxane structure-containing polymer has, for example, an organosiloxane structure in its side chain. From the viewpoint of ease of controlling the adhesive force, an organosiloxane structure-containing acrylic polymer is preferably used as the organosiloxane structure-containing polymer.

The organosiloxane structure-containing polymer is preferably a unit derived from a polymer (specifically, a monomer having an organosiloxane skeleton) obtained by polymerizing a monomer component (second monomer component) containing a monomer having an organosiloxane skeleton. Polymer). Examples of the monomer having an organosiloxane skeleton include a compound represented by the following general formula (1) and a compound represented by the general formula (2). In the general formulas (1) and (2), R ₁ represents a hydrogen or a methyl group, R ₂ represents a methyl group or a monovalent organic group, and m and n are integers of 0 or more.

A commercially available product can also be used as the organosiloxane skeleton-containing monomer. Examples of the commercially available products include X-22-174ASX, X-22-2426, X-22-2475, and KF-22 (all, one-ended reactive silicone manufactured by Shin-Etsu Chemical Co., Ltd.).

The functional group equivalent of the organosiloxane skeleton-containing monomer is preferably 700 g / mol or more from the viewpoint of ensuring low adhesiveness (that is, light peelability of the adhesive sheet X) before the increase in adhesive strength in the adhesive layer 20. It is preferably 800 g / mol or more, more preferably 850 g / mol or more, and more preferably 1500 g / mol or more. From the viewpoint of ensuring the adhesive strength of the pressure-sensitive adhesive layer 20 after the adhesive strength is increased, the functional group equivalent is preferably 20000 g / mol or less, more preferably 15000 g / mol or less, more preferably 10000 g / mol or less, and more preferably. Is 6000 g / mol or less, more preferably 5000 g / mol or less.

The functional group equivalent (g / mol) of the organosiloxane skeleton-containing monomer means the mass (g) of the organosiloxane skeleton bonded per functional group (1 mol) such as a vinyl group involved in the polymerization reaction. This functional group equivalent can be calculated from, for example, the spectral intensity of ^{1 1} H-NMR. ^{1 The} functional group equivalent (g / mol) based on the spectral intensity of ¹ H-NMR is described in Japanese Patent No. 5591153, if necessary, based on a general structural analysis method according to ^{1 1} H-NMR spectrum analysis. Obtained by reference.

The ratio of the organosiloxane skeleton-containing monomer in the second monomer component is preferably 10% by mass from the viewpoint of ensuring low adhesiveness (that is, light peelability of the adhesive sheet X) before the increase in adhesive strength in the adhesive layer 20. As mentioned above, it is more preferably 15% by mass or more, and more preferably 20% by mass or more. From the viewpoint of ensuring the adhesive strength of the pressure-sensitive adhesive layer 20 after the increase in the adhesive strength, the same ratio is preferably 60% by mass or less, more preferably 50% by mass or less, more preferably 40% by mass or less, and more preferably 30. It is mass% or less.

The second monomer component may preferably contain one or more other monomers copolymerizable with the monomer, together with the organosiloxane skeleton-containing monomer. Examples of such monomers include the (meth) acrylic acid alkyl esters described above with respect to acrylic polymers as base polymers and various copolymerizable monomers. The ratio of the other monomer in the second monomer component is preferably 30 from the viewpoint of ensuring compatibility between the acrylic polymer and the organosiloxane structure-containing polymer when the pressure-sensitive adhesive layer 20 contains an acrylic polymer as a base polymer. It is by mass% or more, more preferably 50% by mass or more, and more preferably 70% by mass or more. The same ratio is, for example, 90% by mass or less.

The second monomer component preferably contains a monomer having a homopolymer glass transition temperature of 40 ° C. or higher. The glass transition temperature of the monomer is preferably 80 ° C. or higher, more preferably 100 ° C. or higher. The proportion of the monomer in the second monomer component is preferably 10% by mass or more, more preferably 20% by mass or more, and more preferably 30% by mass or more from the viewpoint of adjusting the adhesive force in the pressure-sensitive adhesive layer 20. .. From the viewpoint of ensuring the compatibility between the organosiloxane structure-containing polymer and the base polymer, the same ratio is preferably 80% by mass or less, more preferably 60% by mass or less, and more preferably 50% by mass or less.

Examples of the monomer having a glass transition temperature of the homopolymer of 40 ° C. or higher include dicyclopentanyl methacrylate (Tg: 175 ° C.), dicyclopentanyl acrylate (Tg: 120 ° C.), and isobornyl methacrylate (Tg: 173 ° C.). ), Isobornyl acrylate (Tg: 97 ° C.), Methyl methacrylate (Tg: 105 ° C.), 1-adamantyl methacrylate (Tg: 250 ° C.), and 1-adamantyl acrylate (Tg: 153 ° C.).

The organosiloxane structure-containing polymer can be formed by polymerizing the above-mentioned second monomer component. Examples of the polymerization method include solution polymerization, bulk polymerization, and emulsion polymerization, and solution polymerization is preferable. In solution polymerization, for example, a second monomer component and, for example, the above-mentioned polymerization initiator are mixed with a solvent to prepare a reaction solution, and then the reaction solution is heated. Then, a polymer solution containing an organosiloxane structure-containing polymer can be obtained by undergoing a polymerization reaction of the second monomer component in the reaction solution. In this polymerization reaction, a chain transfer agent may be used to adjust the molecular weight of the polymer to be formed.

The weight average molecular weight of the organosiloxane structure-containing polymer is preferably 3000 or more, more preferably 3000 or more, from the viewpoint of suppressing bleed-out of the organosiloxane structure-containing polymer from the base polymer and adjusting the adhesive force in the pressure-sensitive adhesive layer 20. It is 5000 or more, more preferably 10000 or more. From the viewpoint of ensuring compatibility between the organosiloxane structure-containing polymer and the base polymer, the molecular weight is preferably 1,000,000 or less, more preferably 500,000 or less, and more preferably 300,000 or less. The weight average molecular weight of the organosiloxane structure-containing polymer is measured by gel permeation chromatography (GPC) and calculated in terms of polystyrene.

The blending amount of the organosiloxane structure-containing polymer with respect to 100 parts by mass of the base polymer is, for example, 0.1 parts by mass or more, preferably 0.3 parts by mass or more, from the viewpoint of adjusting the adhesive force in the pressure-sensitive adhesive layer 20. It is more preferably 0.5 parts by mass or more, and more preferably 1 part by mass or more. From the viewpoint of adjusting optical characteristics such as haze, the blending amount is, for example, 30 parts by mass or less, preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and more preferably 3 parts by mass or less.

The color-developing compound is a compound that changes from colorless (transparent) to colored by reaction with an acid, and is, for example, a leuco-based dye, triarylmethane such as p, p', p "-tris-dimethylaminotriphenylmethane. Diphenylmethane dyes such as 4,4-bis-dimethylaminophenylbenzhydrylbenzyl ether, fluorane dyes such as 3-diethylamino-6-methyl-7-chlorofluorane, 3-methylspirodinaphthopyran, etc. Spiropyran dyes and rhodamine dyes such as rhodamine-B-anilinolactam can be mentioned. The first adhesive composition may contain one kind of chromogenic compound or two or more kinds of chromogenic compounds. A compound may be contained. From the viewpoint of ensuring good colorability in the pressure-sensitive adhesive layer 20, the pressure-sensitive adhesive layer 20 preferably contains a leuco-based dye as a color-developing compound.

The blending amount of the color-developing compound with respect to 100 parts by mass of the base polymer is preferably 0.5 parts by mass or more, and more preferably 1 part by mass or more. The blending amount is preferably 5 parts by mass or less, more preferably 2 parts by mass or less.

The photoacid generator is a compound that generates an acid when irradiated with active energy rays, and examples thereof include an onium compound. Onium compounds are provided, for example, in the form of onium salts of onium cations and anions. Examples of onium cations include iodonium and sulfonium. The anion forming the onium salt, for ^{^{^{_{^{example, Cl -, Br -, I}}}}} -, ZnCl 3 -, HSO 3 -, BF 4 -, PF 6 -, AsF 6 -, SbF 6 -, CH 3 SO 3 -, CF _{_{^{_{3 SO 3 -, (C 6}}}} F 5) 4 B -, (C 4 H 9) 4 B - , and the like. The pressure-sensitive adhesive layer 20 may contain one kind of photoacid generator, or may contain two or more kinds of photoacid generators. The pressure-sensitive adhesive layer 20 preferably contains an onium salt composed of sulfonium and (C ₆ F ₅ ) ₄ B ⁻ as an onium compound. Examples of commercially available products of the photoacid generator, for example, available from San-Apro Ltd. of CPI-310B (sulfonium and _{_{_{(C 6 F 5) 4 B}}} - and onium salts) thereof.

The blending amount of the photoacid generator with respect to 100 parts by mass of the base polymer is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and more preferably 2 parts by mass or more. The blending amount is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, more preferably 7 parts by mass or less, and particularly preferably 5 parts by mass or less. The amount of the photoacid generator to 1 part by mass of the color-developing compound is, for example, 1 part by mass or more, preferably 2 parts by mass or more, more preferably 2.5 parts by mass or more, and more preferably 3.5 parts by mass. More than parts, more preferably 5 parts by mass or more, more preferably 7 parts by mass or more. The blending amount is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and more preferably 10 parts by mass or less.

The pressure-sensitive adhesive layer 20 may contain other components if necessary. Other components include, for example, silane coupling agents, tackifiers, plasticizers, softeners, antioxidants, fillers, colorants, antioxidants, surfactants, and antistatic agents.

When the pressure-sensitive adhesive layer 20 is the above-mentioned second type pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer 20 may contain, for example, a base polymer, a photocuring agent, a photopolymerization initiator, the above-mentioned coloring compound, and a thermal acid. It is composed of a second adhesive composition containing a generator, and its adhesive strength is increased by being irradiated with active energy rays. Further, the second type pressure-sensitive adhesive layer 20 is colored by the reaction between the color-developing compound and the acid derived from the thermoacid generator.

As the base polymer, for example, the base polymer described above for the first type pressure-sensitive adhesive layer 20 can be used.

As the photocuring agent, for example, polyfunctional (meth) acrylate can be used. Examples of the polyfunctional (meth) acrylate include polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, polytetramethylene glycol di (meth) acrylate, bisphenol A ethylene oxide-modified di (meth) acrylate, and bisphenol A. Propylene oxide-modified di (meth) acrylate, alkanediol di (meth) acrylate, tricyclodecanedimethanol di (meth) acrylate, pentaeristol di (meth) acrylate, neopentyl glycol di (meth) acrylate, glycerindi (meth) ) Acrylate, tri (meth) acrylate isocyanurate acrylate, pentaerythtoyl tri (meth) acrylate, and trimethyl propantri (meth) acrylate.

Examples of the photopolymerization initiator include a photocation initiator and a photoradical initiator. Examples of the photoinitiator include hydroxyketones such as 1-hydroxycyclohexylphenylketone, benzyldimethylketals, aminoketones, acylphosphine oxides, benzophenones, and trichloromethyl group-containing triazine derivatives. When a polyfunctional (meth) acrylate is used as the above-mentioned photocuring agent, a photoradical initiator is preferably used as the photopolymerization initiator, and hydroxyketones are more preferably used.

The second adhesive composition may contain a cross-linking agent from the viewpoint of introducing a cross-linked structure into the base polymer. When the base polymer has a cross-linking point, the cross-linking agent for reacting with the cross-linking point to form a cross-linked structure includes, for example, the above-mentioned various cross-linking agents, that is, isocyanate-based cross-linking agent, epoxy-based cross-linking agent, and oxazoline-based cross-linking agent. Examples thereof include cross-linking agents, aziridine-based cross-linking agents, carbodiimide-based cross-linking agents, and metal chelate-based cross-linking agents.

The thermoacid generator is a compound that generates an acid by heating, and examples thereof include aryl sulfonium salts and aryl iodonium salts.

The thickness of the pressure-sensitive adhesive layer 20 is, for example, 5 μm or more, preferably 10 μm or more, and more preferably 15 μm or more, from the viewpoint of ensuring sufficient adhesiveness to the adherend. From the viewpoint of handleability of the pressure-sensitive adhesive sheet X, the thickness of the pressure-sensitive adhesive layer 20 is, for example, 300 μm or less, preferably 100 μm or less, and more preferably 50 μm or less.

In the pressure-sensitive adhesive sheet X, after being bonded to the stainless steel plate, in a peeling test under the peeling conditions of 23 ° C., a peeling angle of 180 ° and a peeling speed of 300 mm / min, the first adhesive force shown to the stainless steel plate is applied to the stainless steel plate. After the bonding and the irradiation with ultraviolet rays under the irradiation conditions of the irradiation wavelength of 365 nm and the irradiation light amount of 4000 mJ / cm ² , the ratio of the second adhesive force shown to the stainless steel plate in the peeling test under the above peeling conditions is preferable. Is 2 or less, more preferably 1.7 or less, and more preferably 1.5 or less. The first adhesive strength is preferably 1.5 N / 25 mm or less, more preferably 1.2 N / 25 mm or less, and more preferably 1 N / 25 mm or less. The second adhesive strength is preferably 2N / 25mm or less, more preferably 1.7N / 25mm or less, and more preferably 1.4N / 25mm or less. In these configurations, in the pressure-sensitive adhesive layer 20 of the pressure-sensitive adhesive sheet X, the rate of increase in the adhesive force against the adherend surface due to receiving the first external stimulus is suppressed, and the increase in the adhesive force against the adherend surface due to receiving the second external stimulus is suppressed. Suitable for securing the rate.

Regarding the pressure-sensitive adhesive sheet X of the present invention, after being bonded to a stainless steel plate, a peeling test under a peeling condition of 23 ° C., a peeling angle of 180 ° and a peeling speed of 300 mm / min was applied to the first adhesive force shown on the stainless steel plate. After laminating to a stainless steel plate, irradiating with ultraviolet rays under irradiation conditions of an irradiation wavelength of 365 nm and an irradiation amount of 4000 mJ / cm ² , and heating at 80 ° C. for 5 minutes, the stainless steel plate was subjected to a peeling test under the above peeling conditions. The ratio of the third adhesive force shown to the above is preferably 5 or more, more preferably 10 or more, and more preferably 15 or more. The third adhesive strength is preferably 5N / 25mm or more, more preferably 10N / 25mm or more, and more preferably 15N / 25mm or more. These configurations are suitable for ensuring high adhesive reliability with respect to the adherend surface in the adhesive sheet X bonded to the adherend surface.

The visible light transmittance at a wavelength of 550 nm before the pressure-sensitive adhesive layer 20 in the pressure-sensitive adhesive sheet X receives the first external stimulus is preferably 85% or more, more preferably 87% or more, and more preferably 90% or more. Such a configuration is suitable for inspecting the presence or absence of foreign matter or air bubbles between the pressure-sensitive adhesive sheet X and its adherend surface after the pressure-sensitive adhesive sheet X is bonded to a predetermined surface.

The visible light transmittance at a wavelength of 550 nm after the pressure-sensitive adhesive layer 20 in the pressure-sensitive adhesive sheet X is subjected to the first external stimulus is preferably 80% or less, more preferably 78% or less, and more preferably 76% or less. Such a configuration is suitable for making it difficult to visually recognize the adherend surface to which the adhesive sheet X is attached, and is also suitable for preventing / suppressing the above-mentioned external light reflection on the adherend surface.

The visible average light transmittance at a wavelength of 300 to 700 nm before the pressure-sensitive adhesive layer 20 in the pressure-sensitive adhesive sheet X receives the first external stimulus is preferably 83% or more, more preferably 84% or more. Such a configuration is suitable for inspecting the presence or absence of foreign matter or air bubbles between the pressure-sensitive adhesive sheet X and its adherend surface after the pressure-sensitive adhesive sheet X is bonded to a predetermined surface.

The visible average light transmittance at a wavelength of 300 to 700 nm after the pressure-sensitive adhesive layer 20 in the pressure-sensitive adhesive sheet X is subjected to the first external stimulus is preferably 75% or less, more preferably 72% or less, and more preferably 70% or less. Is. Such a configuration is suitable for making it difficult to visually recognize the adherend surface to which the adhesive sheet X is attached, and is also suitable for preventing / suppressing the above-mentioned external light reflection on the adherend surface.

The haze of the adhesive sheet X before receiving the first external stimulus is preferably 3% or less, more preferably 2% or less, and more preferably 1% or less. Such a configuration is suitable for inspecting the presence or absence of foreign matter or air bubbles between the pressure-sensitive adhesive sheet X and its adherend surface after the pressure-sensitive adhesive sheet X is bonded to a predetermined surface.

For the pressure-sensitive adhesive sheet X, for example, a pressure-sensitive adhesive composition containing various components for forming the pressure-sensitive adhesive layer 20 is applied onto the base material 10 to form a coating film, and the solvent is dried from the coating film as needed. It can be manufactured by removing it. Examples of the method of applying the adhesive composition include roll coat, kiss roll coat, gravure coat, reverse coat, roll brush, spray coat, dip roll coat, bar coat, knife coat, air knife coat, curtain coat and lip coat. , And die coat. The drying temperature for removing the solvent is, for example, 50 ° C. to 200 ° C. The drying time is, for example, 5 seconds to 10 minutes.
When the tacky composition used contains a cross-linking agent, the cross-linking reaction involving the cross-linking agent in the sticky composition is promoted at the same time as the above-mentioned drying or by the subsequent aging. The aging conditions are appropriately set depending on the type of the cross-linking agent. The aging temperature is, for example, 20 ° C to 160 ° C. The aging time is, for example, 1 minute to 7 days. Further, with respect to the manufactured pressure-sensitive adhesive sheet X, a release film may be laminated on the pressure-sensitive adhesive surface 21 side of the pressure-sensitive adhesive layer 20, if necessary.
Examples of such a release film include flexible plastic films such as polyethylene film, polypropylene film, polyethylene terephthalate film, and polyester film.

As described above, the pressure-sensitive adhesive layer 20 in the pressure-sensitive adhesive sheet X can reduce the visible light transmittance at a wavelength of 550 nm due to the first external stimulus (the wavelength of 550 nm is within the intermediate region in the wavelength range of visible light). Since it is located, the transmittance of light having a wavelength of 550 nm in the pressure-sensitive adhesive layer 20 tends to affect the color of the pressure-sensitive adhesive layer 20 and the transparency in the visible light region). Such a configuration is suitable for properly using the state where the transparency in the visible light region is relatively high and the state where the transparency is relatively low in the pressure-sensitive adhesive sheet X. For example, after the adhesive sheet X is attached to a predetermined surface, the presence or absence of foreign matter or air bubbles between the adhesive sheet X and the adherend surface is inspected in a state where the adhesive sheet X has relatively high transparency, and the inspection is passed. After that, it is possible to give a first external stimulus to the pressure-sensitive adhesive layer 20 of the sheet to change the transparency of the sheet to a relatively low state. The lower the transparency of the adhesive sheet X attached to the adherend surface, the more difficult it is to see the color and texture of the adherend surface, these differences within the adherend surface, and the outside light on the adherend surface. External light reflection is suppressed even on a surface that is prone to reflection.

As described above, the pressure-sensitive adhesive layer 20 in the pressure-sensitive adhesive sheet X can increase its adhesive strength due to the second external stimulus. In such a configuration, in the pressure-sensitive adhesive sheet X or the pressure-sensitive adhesive layer 20 thereof, a state in which the adhesive force to the adherend is relatively low (low adhesive force state) and a state in which the adhesive force is relatively high (high adhesive force state) are used properly. Suitable for. For example, when a defect occurs in the bonding of the pressure-sensitive adhesive sheet X to a predetermined surface, the sheet is covered with the pressure-sensitive adhesive layer 20 of the pressure-sensitive adhesive sheet X having a relatively low adhesive strength. It can be peeled off from the landing surface. On the other hand, with respect to the pressure-sensitive adhesive sheet X appropriately bonded to a predetermined surface, it is possible to give a second external stimulus to the pressure-sensitive adhesive layer 20 to change the adhesive strength of the same layer to a relatively high state. Is. The higher the adhesive strength of the pressure-sensitive adhesive sheet X or its pressure-sensitive adhesive layer 20 bonded to the adherend surface to the adherend surface, the easier it is to realize high adhesive reliability with respect to the adherend surface in the adhesive sheet X.

As described above, the adhesive sheet X is suitable for ensuring ease of inspection and reworkability regarding bonding to the bonded surface, and has high adhesive reliability and low transparency on the bonded surface. Suitable for achieving sex. Such an adhesive sheet X can be suitably used as a reinforcing adhesive sheet X to be attached to the surface of various devices such as optical devices and electronic devices. Further, the adhesive sheet X can be suitably used as an external light reflection inhibitor to be attached to a display panel provided in a display device such as an organic electroluminescence display.

FIG. 2 shows a method for manufacturing an adhesive sheet-attached product according to an embodiment of the present invention. This manufacturing method includes a preparation step, a bonding step, a coloring step, and an adhesive strength increasing step.

In the preparation process, as shown in FIG. 2A, the adhesive sheet X and the adherend 30 are prepared. Examples of the adherend 30 include a flexible optical device such as a flexible display panel, a flexible electronic device such as a flexible printed wiring board (FPC), and a flexible base material as a component thereof.

In the bonding step, as shown in FIG. 2B, the pressure-sensitive adhesive sheet X is bonded to the adherend 30 with the pressure-sensitive adhesive layer 20.

Next, in the coloring step, the first external stimulus is applied to the pressure-sensitive adhesive layer 20 on the adherend 30. When the pressure-sensitive adhesive layer 20 is a first-type pressure-sensitive adhesive layer, the first external stimulus is irradiation with active energy rays, and when the pressure-sensitive adhesive layer 20 is a second-type pressure-sensitive adhesive layer, the first external stimulus is heated. Is. In this step, the visible light transmittance at the wavelength of 550 nm is lowered in the pressure-sensitive adhesive layer 20, and therefore the visible light transmittance of the pressure-sensitive adhesive sheet X is lowered. As a result, as shown in FIG. 2C, the pressure-sensitive adhesive layer 20 is colored. When the pressure-sensitive adhesive layer 20 is a first-type pressure-sensitive adhesive layer, a visible light transmittance-reduced region can be patterned in this step. Specifically, as shown in FIG. 3, the pressure-sensitive adhesive layer 20 is formed by irradiating the pressure-sensitive adhesive layer 20 with active energy rays through a mask pattern for masking a predetermined region of the pressure-sensitive adhesive layer 20. The area not masked by the mask pattern can be colored by lowering the visible light transmittance to form a pattern of the colored area 20A.

Next, in the adhesive strength increasing step, a second external stimulus is applied to the adhesive layer 20 on the adherend 30. When the pressure-sensitive adhesive layer 20 is a first-type pressure-sensitive adhesive layer, the second external stimulus is heating, and when the pressure-sensitive adhesive layer 20 is a second-type pressure-sensitive adhesive layer, the second external stimulus is irradiation with active energy rays. Is. In this step, the adhesive strength of the pressure-sensitive adhesive layer 20 to the adherend 30 is reduced.

In the present manufacturing method, the surfaces of the adhesive sheet X and the adherend 30 (covered) in a state where the adhesive sheet X has relatively high transparency after the bonding step and before the coloring step and the adhesive strength increasing step. It is possible to inspect the presence or absence of foreign matter or air bubbles between the surface and the surface 31). As a result of the inspection, when it is necessary to redo the adhesive sheet bonding work, in this manufacturing method, the adhesive sheet X having a relatively low adhesive force is applied to the adherend surface before the coloring step and the adhesive force increasing step. It can be peeled off from 31 and then another adhesive sheet X can be attached (ie, the bonding operation can be reworked). Then, with respect to the pressure-sensitive adhesive sheet X that has undergone an appropriate bonding operation, the transparency of the pressure-sensitive adhesive layer 20 can be reduced by undergoing a coloring step, and then the pressure-sensitive adhesive layer 20 is subjected to a step of increasing the adhesive strength. In, it is possible to increase the adhesive force and secure high adhesive reliability with respect to the adherend surface.

As described above, this manufacturing method is suitable for ensuring ease of inspection and reworkability regarding the bonding of the adhesive sheet X to the adherend surface 31 in the manufacturing process of the adhesive sheet affixed product, and is adhered. The adhesive sheet X bonded to the surface 31 is suitable for achieving high adhesive reliability and low transparency.

In addition, when the pressure-sensitive adhesive layer 20 is the first type pressure-sensitive adhesive layer and the colored region is patterned on the pressure-sensitive adhesive layer 20 in the coloring step, even if the colored region 20A is misaligned, the present invention In the manufacturing method, it is possible to peel off the adhesive sheet X having a relatively low adhesive force from the adherend surface before the step of increasing the adhesive force, and then rework the adhesive sheet bonding work. it can.

The method for manufacturing the adhesive sheet-attached product according to another embodiment of the present invention includes a preparation step, a bonding step, an adhesive strength increasing step, and a coloring step.

In the preparation process, as shown in FIG. 2A, the adhesive sheet X and the adherend 30 are prepared. In the bonding step, as shown in FIG. 2B, the pressure-sensitive adhesive sheet X is bonded to the adherend 30 with the pressure-sensitive adhesive layer 20.

Next, in the adhesive strength increasing step, a second external stimulus is applied to the adhesive layer 20 on the adherend 30. When the pressure-sensitive adhesive layer 20 is a first-type pressure-sensitive adhesive layer, the second external stimulus is heating, and when the pressure-sensitive adhesive layer 20 is a second-type pressure-sensitive adhesive layer, the second external stimulus is irradiation with active energy rays. Is. In this step, the adhesive strength of the pressure-sensitive adhesive layer 20 to the adherend 30 is increased.

Next, in the coloring step, the first external stimulus is applied to the pressure-sensitive adhesive layer 20 on the adherend 30. When the pressure-sensitive adhesive layer 20 is a first-type pressure-sensitive adhesive layer, the first external stimulus is irradiation with active energy rays, and when the pressure-sensitive adhesive layer 20 is a second-type pressure-sensitive adhesive layer, the first external stimulus is heated. Is. In this step, the visible light transmittance at the wavelength of 550 nm is lowered in the pressure-sensitive adhesive layer 20, and therefore the visible light transmittance of the pressure-sensitive adhesive sheet X is lowered. As a result, as shown in FIG. 2C, the pressure-sensitive adhesive layer 20 is colored.

In the present manufacturing method, the surfaces of the adhesive sheet X and the adherend 30 (covered) in a state where the adhesive sheet X has relatively high transparency after the bonding step and before the coloring step and the adhesive strength increasing step. It is possible to inspect the presence or absence of foreign matter or air bubbles between the surface and the surface 31). As a result of the inspection, when it is necessary to redo the adhesive sheet bonding work, in this manufacturing method, the adhesive sheet X having a relatively low adhesive force is applied to the adherend surface before the coloring step and the adhesive force increasing step. It can be peeled from 31 and then another adhesive sheet X can be attached (ie, the adhesive sheet attaching operation can be reworked). Then, with respect to the adhesive sheet X that has undergone appropriate bonding work, the adhesive force is increased in the adhesive layer 20 by undergoing the adhesive force increasing step, and high adhesive reliability with respect to the adherend surface is ensured. Is possible. After that, the transparency of the pressure-sensitive adhesive layer 20 can be lowered by going through a coloring step.

[Example 1]
<Preparation of base polymer>
In a reaction vessel equipped with a stirrer, a thermometer, a reflux cooler, and a nitrogen gas introduction tube, 63 parts by mass of 2-ethylhexyl acrylate (2EHA), 15 parts by mass of N-vinyl-2-pyrrolidone (NVP), and 9 parts by mass of methyl methacrylate (MMA), 13 parts by mass of 2-hydroxyethyl acrylate (HEA), and 0.2 parts by mass of 2,2'-azobisisobutyronitrile (AIBN) as a polymerization initiator. A mixture containing 233 parts by mass of ethyl acetate as a solvent (reaction solution containing the first monomer component) was stirred at 60 ° C. for 7 hours in a nitrogen atmosphere (polymerization reaction). This gave a polymer solution containing an acrylic polymer (Polymer P _1). The weight average molecular weight of the polymer P ₁ of the polymer solution (Mw) of 460,000.

<Preparation of polymer containing organosiloxane structure>
In a four-necked flask equipped with a stirrer, a thermometer, a reflux cooler, a nitrogen gas introduction tube, and a dropping funnel, 40 parts by mass of methyl methacrylate (MMA), 20 parts by mass of n-butyl methacrylate (BMA), and 20 parts by mass of 2-ethylhexyl methacrylate (2EHMA) and 8.7 parts by mass of the first polyorganosiloxane skeleton-containing methacrylate monomer (trade name: X-22-174ASX, functional group equivalent 900 g / mol, manufactured by Shinetsu Chemical Industry Co., Ltd.) , 2nd polyorganosiloxane skeleton-containing methacrylate monomer (trade name: KF-2012, functional group equivalent 4600 g / mol, manufactured by Shin-Etsu Chemical Industry Co., Ltd.) 11.3 parts by mass and methyl thioglycolate as a chain transfer agent 0.51 A mixture containing parts by mass and 100 parts by mass of toluene as a solvent (a reaction solution containing a second monomer component) is stirred at 70 ° C. for 1 hour in a nitrogen atmosphere, and then the mixture is added as a thermal polymerization initiator. 0.2 parts by mass of AIBN was added, and the mixture was stirred at 70 ° C. for 2 hours under a nitrogen atmosphere (polymerization reaction). Then, 0.1 part by mass of AIBN was added to the reaction mixture, and the mixture was stirred at 80 ° C. for 5 hours in a nitrogen atmosphere (polymerization reaction). Thus, to obtain a polymer solution containing an organosiloxane structure-containing polymer (Polymer P _2). The Mw of this polymer P ₂ was 22000.

<Preparation of adhesive composition>
In the above-mentioned polymer solution containing the polymer P ₁ , ₂ parts by mass of the polymer P ₂ per 100 parts by mass of the polymer P ₁ and an isocyanate-based cross-linking agent (trade name: Takenate D110N, xiri) as a cross-linking agent (cross-linking agent C ₁ ). A trimethylolpropane adduct of range isocyanate, manufactured by Mitsui Chemicals, 1.1 parts by mass, a leuco dye as a color-developing compound (trade name: BLACK ND1, manufactured by Yamada Chemical Industries), and a photoacid generator (manufactured by Yamada Chemical Industries). trade name: CPI-310B, sulfonium and _{_{_{(C 6 F 5) 4 B}}} - onium salts with, and mixed with the SAN-APRO Ltd.) 2 parts by weight to obtain an adhesive composition.

<Making an adhesive sheet>
An adhesive composition was applied onto a polyethylene terephthalate film (PET film) having a thickness of 75 μm using a fountain roll to form a coating film. Next, this coating film was heat-dried at 130 ° C. for 1 minute to form an adhesive layer having a thickness of 25 μm on the PET film. Next, the release-treated surface of the separator (a polyethylene terephthalate film having a thickness of 25 μm whose surface was treated with silicone release treatment) was attached to the pressure-sensitive adhesive layer on the PET film. Then, the aging treatment was carried out at 25 ° C. for 4 days to allow the cross-linking reaction in the pressure-sensitive adhesive layer to proceed. As described above, the pressure-sensitive adhesive sheet of Example 1 was produced. The composition of the pressure-sensitive adhesive sheet of Example 1 in the pressure-sensitive adhesive layer is listed in Table 1 in units of mass (the same applies to Examples and Comparative Examples described later).

[Example 2]
In the preparation of the adhesive composition, the amount of the leuco-based dye was changed to 2 parts by mass instead of 1 part by mass, and the amount of the photoacid generator was changed to 5 parts by mass instead of 2 parts by mass. Except for the above, the pressure-sensitive adhesive sheet of Example 2 was produced in the same manner as the pressure-sensitive adhesive sheet of Example 1.

[Example 3]
In the preparation of the adhesive composition, the amount of the leuco-based dye was changed to 2 parts by mass instead of 1 part by mass, and the amount of the photoacid generator was changed to 7 parts by mass instead of 2 parts by mass. Except for the above, the pressure-sensitive adhesive sheet of Example 3 was produced in the same manner as the pressure-sensitive adhesive sheet of Example 1.

[Example 4]
In the preparation of the adhesive composition, as a base polymer in place of the polymer P ₁ 100 parts by mass for the use of polymer P ₃ 100 parts by weight of the following, the crosslinking agents C ₁ to place of crosslinking agent C ₂ as a crosslinking agent ( Product name "Tetrad C", 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, manufactured by Mitsubishi Gas Chemicals, Ltd. 0.075 parts by mass was used, and the amount of leuco dye was 1 part by mass. In the same manner as the pressure-sensitive adhesive sheet of Example 1, except that 2 parts by mass was used instead of 2 parts and the amount of the photoacid generator was 7 parts by mass instead of 2 parts by mass. An adhesive sheet was prepared.

<Preparation of Polymer _{P 3>}
Initiation of polymerization with 95 parts by mass of n-butyl (BA) acrylate and 5 parts by mass of acrylic acid (AA) in a reaction vessel equipped with a stirrer, thermometer, reflux cooler, nitrogen gas introduction tube, and dropping funnel. A mixture containing 0.2 parts by mass of 2,2'-azobisisobutyronitrile (AIBN) as an agent and 233 parts by mass of ethyl acetate as a solvent was stirred at 60 ° C. for 8 hours in a nitrogen atmosphere. (Polymerization reaction). This gave a polymer solution containing an acrylic polymer (Polymer P _3). The weight average molecular weight of the polymer P ₃ of the polymer solution (Mw) of 600,000.

[Comparative Example 1]
A pressure-sensitive adhesive sheet of Comparative Example 1 was prepared in the same manner as the pressure-sensitive adhesive sheet of Example 1 except that a leuco-based dye and a photoacid generator were not used in the preparation of the pressure-sensitive adhesive composition.

[Comparative Example 2]
Except for not using the polymer P ₂ in the preparation of the adhesive composition in the same manner as the pressure-sensitive adhesive sheet of Example 1 to produce a pressure-sensitive adhesive sheet of Comparative Example 2.

<Transmittance>
For each of the adhesive sheets of Examples 1 to 4 and Comparative Examples 1 and 2, a transmittance measuring device (trade name: spectrophotometer U4100, manufactured by Hitachi High-Technologies Co., Ltd.) was used to determine the visible light transmittance at a wavelength of 550 nm. The average visible light transmittance at a wavelength of 300 to 700 nm was measured (transmittance before UV irradiation). Further, after irradiating each of the pressure-sensitive adhesive sheets of Examples 1 to 4 and Comparative Examples 1 and 2 with ultraviolet rays, the visible light transmittance at a wavelength of 550 nm and a wavelength of 300 to 700 nm are used by using the above-mentioned transmittance measuring device. The average visible light transmittance of the above was measured (transmittance after UV irradiation). In the ultraviolet irradiation, an LED lamp was used as a light source, the irradiation wavelength was 365 nm, and the irradiation light amount was 4000 mJ / cm ² . Further, in these transmittance measurements, in a transmittance measuring device provided with a light source and a detector, the adhesive sheet is placed in the device so that the adhesive layer of the adhesive sheet is located on the light source side and the base material of the sheet is located on the detector side. After installing in, the measurement was performed. The measurement results are listed in Table 1.

<First adhesive strength>
The first adhesive force as the initial adhesive force was examined for the pressure-sensitive adhesive layers in the pressure-sensitive adhesive sheets of Examples 1 to 4 and Comparative Examples 1 and 2 as follows. First, a sample piece (width 25 mm × length 100 mm) was cut out from the adhesive sheet. Next, the sample piece was attached to a SUS plate as an adherend, and the sample piece and the adherend were crimped by a crimping operation in which a 2 kg roller was reciprocated once. Next, after leaving for 30 minutes (first standing) in an environment of 25 ° C. and 50% relative humidity, a tensile tester (trade name "Autograph AGS-J", manufactured by Shimadzu Corporation) was used. It was measured 180 ° peel adhesive strength of the adhesive sheet test piece for SUS plate (N / 25 mm) as the first adhesive strength _{F 1.} In this measurement, the measurement temperature was 25 ° C., the peeling angle of the sample piece with respect to the SUS plate, that is, the tensile angle was 180 °, and the tensile speed of the sample piece was 300 mm / min. The results are listed in Table 1.

<Second adhesive strength>
The second adhesive strength after coloring by ultraviolet irradiation was examined for the pressure-sensitive adhesive layers in the pressure-sensitive adhesive sheets of Examples 1 to 4 and Comparative Examples 1 and 2. Specifically, after the above-mentioned first standing, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet sample piece is irradiated with ultraviolet rays, and left for 30 minutes in an environment of 25 ° C. and 50% relative humidity (second leaving). further except going through, as in the first adhesive strength measurement was measured 180 ° peel adhesive strength of the adhesive sheet test piece for SUS plate (N / 25 mm) as the second adhesive force F _2. In the ultraviolet irradiation, an LED lamp was used as a light source, the irradiation wavelength was 365 nm, and the irradiation light amount was 4000 mJ / cm ² . The measurement results are listed in Table 1. Table 1 also lists the ratio of the second adhesive force to the first adhesive force (F ₂ / F ₁ ).

<Third adhesive strength>
The third adhesive strength of the pressure-sensitive adhesive layers in the pressure-sensitive adhesive sheets of Examples 1 to 4 and Comparative Examples 1 and 2 after being colored by ultraviolet irradiation and heating was examined. Specifically, after the above-mentioned first standing, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet sample piece is further irradiated with ultraviolet rays, the above-mentioned second standing, and heating of the pressure-sensitive adhesive sheet sample piece at 80 ° C. for 5 minutes. except going through, as in the first adhesive strength measurement was measured 180 ° peel adhesive strength of the adhesive sheet test piece for SUS plate (N / 25 mm) as the third adhesion F _3. In the ultraviolet irradiation, an LED lamp was used as a light source, the irradiation wavelength was 365 nm, and the irradiation light amount was 4000 mJ / cm ² . The measurement results are listed in Table 1. Table 1 also lists the ratio of the third adhesive force to the first adhesive force (F ₃ / F ₁ ).

Industrial applications

The adhesive sheet of the present invention is used as a reinforcing adhesive sheet to be attached to the surface of various devices such as optical devices and electronic devices, for example.

X Adhesive sheet 10 Base material 11 Surface 20 Adhesive layer 20A Colored area 21 Adhesive surface 30 Adhesive body 31 Adhesive surface

Claims

It is characterized by comprising a pressure-sensitive adhesive layer capable of lowering the visible light transmittance at a wavelength of 550 nm due to the first external stimulus and increasing the adhesive strength due to the second external stimulus. Adhesive sheet.
The adhesive sheet according to claim 1, wherein the first external stimulus is irradiation with active energy rays.
The adhesive sheet according to claim 1, wherein the second external stimulus is heating.
After laminating to the stainless steel plate, in the peeling test under the peeling conditions of 23 ° C., peeling angle 180 ° and peeling speed 300 mm / min, the first adhesive force shown to the stainless steel plate is bonded to the stainless steel plate and irradiated. After undergoing ultraviolet irradiation under irradiation conditions of a wavelength of 365 nm and an irradiation light amount of 4000 mJ / cm 2 , the ratio of the second adhesive force shown to the stainless steel plate in the peeling test under the peeling conditions is 2 or less. The adhesive sheet according to claim 1, which is characteristic.
After laminating to the stainless steel plate, in the peeling test under the peeling conditions of 23 ° C., peeling angle 180 ° and peeling speed 300 mm / min, the first adhesive force shown to the stainless steel plate is bonded to the stainless steel plate and irradiated. After UV irradiation under irradiation conditions with a wavelength of 365 nm and an irradiation amount of 4000 mJ / cm 2 and heating at 80 ° C. for 5 minutes, the third adhesive force shown on the stainless steel plate in the peeling test under the peeling conditions. The adhesive sheet according to claim 1, wherein the ratio of the above is 5 or more.
The adhesive sheet according to claim 5, wherein the third adhesive strength is 5 N / 25 mm or more.
The pressure-sensitive adhesive sheet according to claim 1, wherein the visible light transmittance at a wavelength of 550 nm after receiving the first external stimulus is 80% or less.
The adhesive sheet according to claim 1, wherein the visible light average transmittance at a wavelength of 300 to 700 nm after receiving the first external stimulus is 75% or less.
The pressure-sensitive adhesive sheet according to claim 1, wherein the pressure-sensitive adhesive layer comprises a pressure-sensitive adhesive composition containing a compound that develops color by reaction with an acid and an acid generator.
The pressure-sensitive adhesive sheet according to claim 1, wherein the pressure-sensitive adhesive layer comprises a pressure-sensitive adhesive composition containing a base polymer and an organosiloxane structure-containing polymer.
The adhesive sheet according to claim 10, wherein the base polymer is an acrylic polymer.
The adhesive sheet according to claim 10, wherein the glass transition temperature of the base polymer is 0 ° C. or lower.
The pressure-sensitive adhesive sheet according to claim 10, wherein the organosiloxane structure-containing polymer is a polymer of a monomer component containing a monomer having an organosiloxane structure and a monomer copolymerizable with the monomer.
A step of attaching the adhesive sheet according to claim 1 to an adherend with the adhesive layer, and
A coloring step of applying the first external stimulus to the pressure-sensitive adhesive layer on the adherend,
A method for producing an adhesive sheet-attached product, which comprises a step of increasing the adhesive strength before or after the coloring step of applying the second external stimulus to the pressure-sensitive adhesive layer on the adherend.
The method for manufacturing an adhesive sheet-attached product according to claim 14, wherein the first external stimulus is irradiation with active energy rays.
The method for manufacturing an adhesive sheet-attached product according to claim 14, wherein the second external stimulus is heating.