JP2022182496A - Pressure sensitive adhesive sheet, display device and laminate - Google Patents

Abstract

To provide a pressure sensitive adhesive sheet having double-sided adhesiveness, avoiding a lift or a removal from an adherend even if exposed to an acidic liquid and an alkaline liquid, with a configuration of a limited thickness.SOLUTION: A pressure sensitive adhesive sheet is 100 μm thick or less and has double-sided adhesiveness. The pressure sensitive adhesive sheet includes an acrylic pressure sensitive adhesive layer containing an acrylic polymer. In the pressure sensitive adhesive sheet, 180 degree peeling strength F0 to a stainless steel plate measured at a tensile speed 300 mm/min is 3.0 N/5 mm or more. In the pressure sensitive adhesive sheet, an adhesive force maintenance factor after immersed in an acidic solution and an adhesive force maintenance factor after immersed in an alkaline solution are each 80% or more.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to an adhesive sheet, a display device and a laminate.

In general, pressure-sensitive adhesives (also referred to as pressure-sensitive adhesives; hereinafter the same) exhibit a soft solid (viscoelastic) state in a temperature range around room temperature, and have the property of adhering to adherends under pressure. Taking advantage of these properties, adhesives are used in various industrial fields such as home electric appliances, automobiles, and OA equipment in the form of adhesive sheets with a substrate having an adhesive layer on a supporting substrate, or in the form of a substrate without a supporting substrate. It is in the form of a materialless adhesive sheet and is widely used for purposes such as joining parts and protecting surfaces. Patent Documents 1 to 3 are cited as technical documents relating to pressure-sensitive adhesive sheets. Patent Literature 1 discloses an adhesive sheet used inside a touch panel. Patent Document 2 discloses a pressure-sensitive adhesive sheet having a viscoelastic layer having a thickness of 200 μm or more as a support layer. Patent Document 3 discloses a backgrinding tape used for fixing and protecting a semiconductor wafer in the backgrinding process of semiconductor wafer processing.

JP 2014-34655 A JP 2015-147870 A JP 2017-212441 A

Adhesive sheets are used as so-called structural materials that join or fix members and are incorporated into articles together with the members (for example, Patent Document 1), or are temporarily used during the manufacture, processing, and transportation of various articles that are adherends. It is widely used as a so-called process material (for example, Patent Document 3), in which it is attached to an adherend and removed from the adherend after achieving its purpose. Adhesive sheets used as structural materials, unlike process material applications that require removability from adherends, are usually manufactured with long-term adhesion reliability so that they do not come off from adherends until the end of the life of the product in which the adhesive sheet is incorporated. sexuality is required. For example, adhesive sheets used for fixing members of portable electronic devices tend to have a small adhesion area and a limited thickness due to the tendency of portable electronic devices to be lighter, smaller, and thinner. Generally, as the thickness of the pressure-sensitive adhesive sheet decreases, the pressure-sensitive adhesive strength decreases. Under such restrictions, it is necessary to maintain good adhesion for a long period of time.

In addition, processing such as perforation may be applied to various members of the portable electronic device described above. For example, organic EL (electroluminescence) panels and metal members used in portable electronic devices may be provided with openings for various sensors such as a fingerprint sensor and camera lenses. The processing of the member is usually performed before the adhesive sheet is attached, but if it can be performed with the adhesive sheet attached (for example, the members are joined with the adhesive sheet), it is beneficial in terms of production efficiency. can be. In such a processing step, the pressure-sensitive adhesive sheet, in a state of being attached to a member as an adherend, needs to maintain a good adhesion state to the adherend even after the processing step for the member. . For example, processing such as forming an opening in a metal member may include a chemical treatment process such as an etching process in which a non-processed portion of the metal member is masked and immersed in an acidic etchant. Also, after being immersed in the etching liquid, the metal member may be washed with an alkaline washing liquid or the like. Therefore, the pressure-sensitive adhesive sheet, which is attached to a metal member and subjected to a processing step of the metal member, can be exposed to an acidic etching solution or an alkaline cleaning solution together with the metal member, which is an adherend. It must have properties (acid and alkali resistance) that maintain good adhesion and do not lift or peel off even when exposed to water. If such a pressure-sensitive adhesive sheet having excellent acid resistance and alkali resistance is realized, it is practically useful because it can be applied to the adherend while being attached to the adherend.

The present invention has been created in view of the above circumstances, and has a structure with a limited thickness, and even when exposed to acidic liquids and alkaline liquids, it does not lift or peel off from the adherend. It is an object of the present invention to provide a pressure-sensitive adhesive sheet with double-sided adhesiveness that does not cause such a problem. Another related object is to provide a display device and a laminate having the adhesive sheet.

According to this specification, a double-sided adhesive pressure-sensitive adhesive sheet having a thickness of 100 μm or less is provided. This pressure-sensitive adhesive sheet has an acrylic pressure-sensitive adhesive layer containing an acrylic polymer. The pressure-sensitive adhesive sheet has a 180-degree peel strength F0 to a stainless steel plate measured at a tensile speed of 300 mm/min of 3.0 N/5 mm or more. Further, both the adhesive strength retention rate after immersion in an acidic solution and the adhesive strength retention rate after immersion in an alkaline solution of the adhesive sheet are 80% or more. Here, the adhesive strength retention rate after immersion in the acidic solution [%] is obtained from the ratio (F1/F0×100) of the adhesive strength after immersion in the acidic solution F1 [N/5 mm] to the peel strength F0 [N/5 mm]. be done. The adhesive strength retention rate after immersion in alkaline solution [%] is obtained from the ratio (F2/F0×100) of adhesive strength after immersion in alkaline solution F2 [N/5 mm] to peel strength F0 [N/5 mm]. In addition, the adhesive strength F1 after immersion in the acidic solution was measured by immersing a 5 mm wide adhesive sheet attached to a stainless steel plate as an adherend in an aqueous iron chloride solution (5% FeCl ₂ aqueous solution) for 30 minutes in an environment of 50 ° C. After immersion, the peel strength is measured under the conditions of a tensile speed of 300 mm/min and a peel angle of 180 degrees. The adhesive strength F2 after immersion in the alkaline solution was obtained by immersing a 5 mm wide adhesive sheet attached to a stainless steel plate as an adherend in an aqueous sodium hydroxide solution (50% NaOH aqueous solution) for 30 minutes in an environment of 50 ° C. After that, the peel strength is measured under the conditions of a tensile speed of 300 mm/min and a peel angle of 180 degrees. According to the configuration that satisfies the above characteristics, in spite of having a limited thickness of 100 μm or less, even when the double-sided adhesive surfaces are attached to the adherend and then exposed to acidic liquids and alkaline liquids. Even if there is, lifting and peeling from the adherend can be prevented. The above characteristics are preferably realized by using an acrylic pressure-sensitive adhesive containing an acrylic polymer with a high degree of freedom in molecular design.

The pressure-sensitive adhesive sheet according to some aspects is a substrate-less double-sided adhesive pressure-sensitive adhesive sheet comprising the pressure-sensitive adhesive layer. Since the substrate-less double-sided PSA sheet does not have a substrate, it can be made thinner, and can contribute to miniaturization and space saving of products to which the double-sided PSA sheet is applied. Further, according to the substrate-less pressure-sensitive adhesive sheet, the action of the pressure-sensitive adhesive layer, such as adhesive strength and impact resistance, can be maximized. According to the technique disclosed herein, a double-sided PSA sheet that does not lift or peel off from an adherend even when exposed to an acidic or alkaline liquid is realized without relying on a substrate.

A pressure-sensitive adhesive sheet according to some other embodiments is a double-sided adhesive pressure-sensitive adhesive sheet with a substrate, which further comprises a substrate layer and has the above-described pressure-sensitive adhesive layer on each surface of the substrate layer. For example, a substrate-attached pressure-sensitive adhesive sheet provided with a substrate such as a resin film substrate is excellent in handleability and workability, and thus can be processed into various shapes for use in various applications.

The pressure-sensitive adhesive sheet disclosed herein is suitable for use in fixing members constituting the interior of portable electronic devices. Specifically, since the pressure-sensitive adhesive sheet has a thickness of 100 μm or less and can achieve highly reliable bonding and fixing, it is suitable for use in mobile electronic devices, where there is a strong demand for miniaturization and thinning. Further, for example, various members such as metal members that constitute a portable electronic device may be subjected to processing such as formation of openings for various sensors and camera lenses after the adhesive sheet is attached. Such processing steps may include steps using acidic or alkaline liquids, such as immersion in acidic etchants and cleaning with alkaline cleaning solutions. The pressure-sensitive adhesive sheet disclosed herein can prevent lifting and peeling from the adherend even when used in a manner where the member is fixed and exposed to acidic liquids and alkaline liquids.

Further, according to this specification, there is provided a display device including a display section including a cover member and an organic EL unit, and a support section. In this display device, a double-sided adhesive sheet having a thickness of 100 μm or less is attached to the supporting portion. Further, the pressure-sensitive adhesive sheet has an acrylic pressure-sensitive adhesive layer containing an acrylic polymer. Furthermore, the pressure-sensitive adhesive sheet has a 180-degree peel strength F0 to a stainless steel plate measured at a tensile speed of 300 mm/min of 3.0 N/5 mm or more. The adhesive sheet has an adhesive strength retention rate after immersion in an acidic solution and an adhesive strength retention rate after immersion in an alkaline solution of 80% or more. Here, the adhesive strength retention rate after immersion in the acidic solution [%] is obtained from the ratio (F1/F0×100) of the adhesive strength after immersion in the acidic solution F1 [N/5 mm] to the peel strength F0 [N/5 mm]. be done. The adhesive strength retention rate after immersion in alkaline solution [%] is obtained from the ratio (F2/F0×100) of adhesive strength after immersion in alkaline solution F2 [N/5 mm] to peel strength F0 [N/5 mm]. The adhesive strength F1 after immersion in the acidic solution was obtained by immersing a 5 mm wide adhesive sheet attached to a stainless steel plate as an adherend in an aqueous iron chloride solution (5% FeCl ₂ aqueous solution) for 30 minutes in an environment of 50 ° C. After that, the peel strength is measured under the conditions of a tensile speed of 300 mm/min and a peel angle of 180 degrees. The adhesive strength F2 after immersion in the alkaline solution was obtained by immersing a 5 mm wide adhesive sheet attached to a stainless steel plate as an adherend in an aqueous sodium hydroxide solution (50% NaOH aqueous solution) for 30 minutes in an environment of 50 ° C. After that, the peel strength is measured under the conditions of a tensile speed of 300 mm/min and a peel angle of 180 degrees. The pressure-sensitive adhesive sheet disclosed herein is preferably used as a component (structural material, specifically, member joining means) of the display device as described above.

Further, according to this specification, there is provided a laminate comprising a metal member and an adhesive sheet attached to the surface of the metal member. In this laminate, the adhesive sheet is a double-sided adhesive adhesive sheet having a thickness of 100 μm or less. Further, the pressure-sensitive adhesive sheet has an acrylic pressure-sensitive adhesive layer containing an acrylic polymer. Furthermore, the pressure-sensitive adhesive sheet has a 180-degree peel strength F0 to a stainless steel plate measured at a tensile speed of 300 mm/min of 3.0 N/5 mm or more. The adhesive sheet has an adhesive strength retention rate after immersion in an acidic solution and an adhesive strength retention rate after immersion in an alkaline solution of 80% or more. Here, the adhesive strength retention rate after immersion in the acidic solution [%] is obtained from the ratio (F1/F0×100) of the adhesive strength after immersion in the acidic solution F1 [N/5 mm] to the peel strength F0 [N/5 mm]. be done. The adhesive strength retention rate after immersion in alkaline solution [%] is obtained from the ratio (F2/F0×100) of adhesive strength after immersion in alkaline solution F2 [N/5 mm] to peel strength F0 [N/5 mm]. The adhesive strength F1 after immersion in the acidic solution was obtained by immersing a 5 mm wide adhesive sheet attached to a stainless steel plate as an adherend in an aqueous iron chloride solution (5% FeCl ₂ aqueous solution) for 30 minutes in an environment of 50 ° C. After that, the peel strength is measured under the conditions of a tensile speed of 300 mm/min and a peel angle of 180 degrees. The adhesive strength F2 after immersion in the alkaline solution was obtained by immersing a 5 mm wide adhesive sheet attached to a stainless steel plate as an adherend in an aqueous sodium hydroxide solution (50% NaOH aqueous solution) for 30 minutes in an environment of 50 ° C. After that, the peel strength is measured under the conditions of a tensile speed of 300 mm/min and a peel angle of 180 degrees. The pressure-sensitive adhesive sheet disclosed herein can be preferably used in the form of a laminate attached to a metal member that can be exposed to acidic liquids or alkaline liquids. According to the laminate, even when the adhesive sheet is exposed to acidic liquids and alkaline liquids for processing the metal member, the pressure-sensitive adhesive sheet has a structure with a limited thickness and does not lift or peel off from the metal member. It is possible to maintain a non-sticky state.

1 is a cross-sectional view schematically showing one configuration example of an adhesive sheet; FIG. FIG. 3 is a cross-sectional view schematically showing another configuration example of the adhesive sheet; 1 is a cross-sectional view schematically showing one configuration example of a laminate; FIG. 1 is an exploded perspective view schematically showing a configuration example of a display device; FIG.

Preferred embodiments of the present invention are described below. Matters other than the matters specifically mentioned in the present specification, which are necessary for the implementation of the present invention, are based on the teaching of the implementation of the invention described in the present specification and the common general knowledge at the time of filing. can be understood by those skilled in the art. The present invention can be implemented based on the contents disclosed in this specification and common general technical knowledge in the field. Further, in the following drawings, members and portions having the same function may be denoted by the same reference numerals, and redundant description may be omitted or simplified. In addition, the embodiments described in the drawings are schematic for the purpose of clearly explaining the present invention, and do not necessarily accurately represent the size and scale of the pressure-sensitive adhesive sheet of the present invention that is actually provided as a product. .

As used herein, the term “adhesive” refers to a material that exhibits a soft solid (viscoelastic) state in a temperature range around room temperature and has the property of easily adhering to an adherend under pressure, as described above. . The adhesive used herein generally has a complex tensile modulus E ^* (1 Hz) as defined in "CA Dahlquist, "Adhesion: Fundamental and Practice", McLaren & Sons, (1966) P. 143" It may be a material having properties satisfying <10 ⁷ dyne/cm ² (typically, a material having the above properties at 25°C).

<Structure of Adhesive Sheet>
The pressure-sensitive adhesive sheet disclosed herein is a double-sided adhesive pressure-sensitive adhesive sheet, and may be a substrate-attached pressure-sensitive adhesive sheet having the above pressure-sensitive adhesive layers on both sides of a non-releasable substrate (supporting substrate). , a substrate-less pressure-sensitive adhesive sheet (that is, a pressure-sensitive adhesive sheet having no non-releasable substrate) such as a form in which the pressure-sensitive adhesive layer is held by a release liner. A double-faced pressure-sensitive adhesive sheet is preferably used as a structural material for joining or fixing members, since the adherend can be joined by sticking each side thereof to the adherend. The concept of the adhesive sheet as used herein may include what is called an adhesive tape, an adhesive film, and the like. Moreover, the adhesive sheet disclosed herein may be in the form of a roll or sheet. Alternatively, it may be a pressure-sensitive adhesive sheet processed into various shapes.

FIG. 1 shows a configuration example of a double-sided adhesive type substrate-less pressure-sensitive adhesive sheet (substrate-less double-sided pressure-sensitive adhesive sheet). The pressure-sensitive adhesive sheet 1 shown in FIG. 1 has a configuration in which both surfaces 21A and 21B of a substrate-less pressure-sensitive adhesive layer 21 are protected by release liners 31 and 32 whose release surfaces are at least on the pressure-sensitive adhesive layer side. Alternatively, the pressure-sensitive adhesive sheet has a configuration in which one surface (adhesive surface, first adhesive surface) of a substrate-less adhesive layer is protected by a release liner having release surfaces on both sides, and is wound. When turned, the other surface (adhesive surface, second adhesive surface) of the adhesive layer comes into contact with the back surface of the release liner, so that the second adhesive surface of the adhesive layer is also protected by the release liner. You may be able to do it. The technology disclosed herein can be preferably implemented in such a substrate-less form from the viewpoint of reducing the thickness of the pressure-sensitive adhesive sheet. A substrate-less pressure-sensitive adhesive sheet is advantageous in that it is easy to form a thin layer, and that the pressure-sensitive adhesive properties such as adhesive strength and impact resistance can be maximized.

The adhesive sheet disclosed herein can have, for example, a cross-sectional structure schematically shown in FIG. The pressure-sensitive adhesive sheet 2 shown in FIG. 2 has pressure-sensitive adhesive layers 21 and 22 (both the first pressure-sensitive adhesive layer 21 and the second pressure-sensitive adhesive layer 22, respectively) on each surface (both of which are non-releasable) of a substrate (base layer) 10. ) are respectively provided, and the pressure-sensitive adhesive layers are protected by release liners 31 and 32 whose release surfaces are at least on the pressure-sensitive adhesive layer side. Alternatively, the pressure-sensitive adhesive sheet is provided with a pressure-sensitive adhesive layer (first pressure-sensitive adhesive layer, second pressure-sensitive adhesive layer) on each side of the substrate (both of which are non-releasable), and one of the pressure-sensitive adhesive layers (second pressure-sensitive adhesive layer) 1 pressure-sensitive adhesive layer) may have a structure protected by a release liner having release surfaces on both sides. This type of pressure-sensitive adhesive sheet can be obtained by winding the pressure-sensitive adhesive sheet and bringing the other pressure-sensitive adhesive layer (second pressure-sensitive adhesive layer) into contact with the back surface of the release liner. ) can also be protected by the release liner.

<Characteristics of adhesive sheet>
(Normal adhesive strength F0)
The adhesive sheet disclosed herein is characterized by having a 180-degree peel strength (normal adhesive strength) F0 to a stainless steel plate measured at a tensile speed of 300 mm/min of 3.0 N/5 mm or more. A pressure-sensitive adhesive sheet having the above-described adhesive strength can reliably fix an adherend. The normal adhesive force F0 is more preferably about 3.5 N/5 mm or more, still more preferably 4.0 N/5 mm or more, particularly preferably 4.5 N/5 mm or more, and about 5.0 N/5 mm or more. good too. The pressure-sensitive adhesive sheet having the above-described adhesive strength has adhesive strength suitable for joining and fixing, and is suitable for use in portable electronic devices, for example, where high adhesive reliability is required while the adhesive area and thickness are limited. The upper limit of the adhesive force F0 is not particularly limited, and may be approximately 10 N/5 mm or less (for example, 8 N/5 mm or less). The adhesive force F0 is the peel strength against a stainless steel plate measured under the conditions of a tensile speed of 300 mm/min and a peel angle of 180 degrees based on JIS Z 0237. More specifically, it is described in Examples below. measured by the method The adhesive force F0 on each adhesive surface of the double-sided adhesive sheet may be the same or different.

(Adhesive strength F1 after immersion in acidic solution)
The adhesive sheet disclosed herein has an adhesive strength F1 after immersion in an acidic solution that satisfies an adhesive strength retention rate after immersion in an acidic solution, which will be described later. The adhesive strength F1 after immersion in the acidic solution is about 2.4 N/5 mm or more, preferably about 3.0 N/5 mm or more, more preferably about 3.5 N/5 mm or more, and still more preferably 4.0 N/5 mm or more. , particularly preferably 4.5 N/5 mm or more. According to the PSA sheet exhibiting the adhesive strength F1 after being immersed in an acidic solution as described above, even if it is used in a mode of being exposed to an acidic liquid such as an acidic etching solution, it maintains a good adhesive state to the adherend. be able to. According to the technology disclosed herein, such a PSA sheet with excellent acid resistance is provided. The upper limit of the adhesive strength F1 after immersion in the acidic solution is not particularly limited, and may be approximately 10 N/5 mm or less (eg, 8 N/5 mm or less). The adhesive strength F1 after immersion in the acid solution was obtained by immersing a 5 mm wide adhesive sheet attached to a stainless steel plate as an adherend in an aqueous iron chloride solution (5% FeCl ₂ aqueous solution) for 30 minutes in an environment of 50 ° C. After that, it is the peel strength [N/5 mm] measured under the conditions of a tensile speed of 300 mm/min and a peel angle of 180 degrees, and more specifically, it is measured by the method described in Examples below. The adhesive force F1 after immersion in an acidic solution on each adhesive surface of the double-sided adhesive sheet may be the same or different.

(Adhesive strength F2 after immersion in alkaline solution)
The adhesive sheet disclosed herein has an adhesive strength F2 after immersion in an alkaline solution that satisfies the adhesive strength retention rate after immersion in an alkaline solution, which will be described later. The adhesive force F2 after immersion in the alkaline solution is about 2.4 N/5 mm or more, preferably about 3.0 N/5 mm or more, more preferably about 3.5 N/5 mm or more, and still more preferably 4.0 N/5 mm or more. , particularly preferably 4.5 N/5 mm or more. According to the PSA sheet exhibiting the adhesive strength F2 after being immersed in an alkaline solution as described above, even if it is used in a mode of being exposed to an alkaline liquid such as an alkaline cleaning liquid, for example, it can maintain a good adhesive state to an adherend. can be done. According to the technology disclosed herein, such a PSA sheet with excellent alkali resistance is provided. The upper limit of the adhesive strength F2 after immersion in the alkaline solution is not particularly limited, and may be about 10 N/5 mm or less (for example, 8 N/5 mm or less). The adhesive strength F2 after immersion in the alkaline solution was obtained by immersing a 5 mm wide adhesive sheet attached to a stainless steel plate as an adherend in an aqueous sodium hydroxide solution (50% NaOH aqueous solution) for 30 minutes in an environment of 50 ° C. After that, it is the peel strength [N/5 mm] measured under the conditions of a tensile speed of 300 mm/min and a peel angle of 180 degrees, and more specifically, it is measured by the method described in Examples below. The adhesive force F2 after immersion in alkaline solution on each adhesive surface of the double-sided adhesive sheet may be the same or different.

(Adhesion retention rate after immersion in acidic solution/after immersion in alkaline solution)
The adhesive sheet disclosed herein is characterized by having an adhesive strength retention rate after immersion in an acidic solution and an adhesive strength retention rate after immersion in an alkaline solution of 80% or more. The adhesive strength retention rate after immersion in an acidic solution [%] is obtained from the ratio of the adhesive strength F1 [N/5 mm] after immersion in an acidic solution to the normal state adhesive strength F0 [N/5 mm] (F1/F0 × 100). The post-immersion adhesive strength retention rate [%] is obtained from the ratio (F2/F0×100) of the post-immersion adhesive strength F2 [N/5 mm] to the normal state adhesive strength F0 [N/5 mm]. A pressure-sensitive adhesive sheet that satisfies the above properties can have excellent adhesion reliability such that it does not swell easily and does not lift or peel off even when exposed to acidic or alkaline liquids. At least one (preferably both) of the adhesive strength retention rate after immersion in an acidic solution and the adhesive strength retention rate after immersion in an alkaline solution (preferably both) is preferably 85% or more, more preferably 90% or more, still more preferably 95% or more, and particularly preferably is 100% or more. The upper limit of the adhesive strength retention rate after immersion in an acidic solution and the adhesive strength retention rate after immersion in an alkaline solution are not particularly limited, and may be, for example, 300% or less, 200% or less, or 150% or less. The adhesive strength retention rate after immersion in an acidic solution and the adhesive strength retention rate after immersion in an alkaline solution on each adhesive surface of the double-sided pressure-sensitive adhesive sheet may be the same or different.

(Total thickness of adhesive sheet)
The thickness (total thickness) of the pressure-sensitive adhesive sheet disclosed herein (including a pressure-sensitive adhesive layer and a base layer in a structure having a base layer, but not including a release liner) is 100 µm or less. . Such a pressure-sensitive adhesive sheet having a limited thickness satisfies the demand for thinness and weight reduction, and is suitable for use in portable electronic devices where there is a strong demand for miniaturization and thinness. In addition, according to the technology disclosed herein, the thickness is limited as described above, and it has acid resistance and alkali resistance, can maintain sufficient adhesive strength, and does not float from the adherend. It is possible to obtain a pressure-sensitive adhesive sheet that does not peel off or peel off. The thickness of the adhesive sheet is preferably approximately 70 μm or less, more preferably approximately 50 μm or less, and may be approximately 35 μm or less, for example. The lower limit of the thickness of the adhesive sheet is not particularly limited, and may be approximately 1 μm or more, for example, approximately 3 μm or more, preferably approximately 6 μm or more, more preferably approximately 10 μm or more (for example, approximately 15 μm). above), more preferably about 20 μm or more. A pressure-sensitive adhesive sheet having a thickness greater than or equal to a predetermined value tends to be easy to handle, and to have excellent adhesive strength and resistance to permeation of acidic liquids and alkaline liquids in the thickness direction. In addition, in the substrate-less adhesive sheet, the thickness of the adhesive layer is the total thickness of the adhesive sheet.

<Adhesive layer>
(Acrylic polymer)
The pressure-sensitive adhesive layer constituting the pressure-sensitive adhesive sheet disclosed herein is an acrylic pressure-sensitive adhesive layer containing an acrylic polymer. The pressure-sensitive adhesive layer is typically a pressure-sensitive adhesive layer containing an acrylic polymer as a base polymer (the main component of the polymer component, that is, the component occupying 50% by weight or more). Such an adhesive layer is also called an acrylic adhesive layer. By using an acrylic pressure-sensitive adhesive containing an acrylic polymer with a high degree of freedom in molecular design, the above pressure-sensitive adhesive sheet properties can be preferably realized. The base polymer is the main component of the rubber-like polymer (polymer exhibiting rubber elasticity in a temperature range around room temperature) contained in the pressure-sensitive adhesive layer. In this specification, the term "main component" refers to a component contained in an amount exceeding 50% by weight unless otherwise specified.

In this specification, the term "acrylic polymer" refers to a polymer containing monomer units derived from a monomer having at least one (meth)acryloyl group in one molecule as a monomer unit constituting the polymer, Also called acrylic polymer. Hereinafter, a monomer having at least one (meth)acryloyl group in one molecule is also referred to as "acrylic monomer". In addition, "(meth)acryloyl" is a generic term for acryloyl and methacryloyl. Similarly, "(meth)acrylate" is a generic term for acrylate and methacrylate, and "(meth)acrylic" is generic for acrylic and methacrylic.

As the acrylic polymer in the technique disclosed herein, for example, a polymer of monomer raw materials containing an alkyl (meth)acrylate as a main monomer and further containing a sub-monomer copolymerizable with the main monomer is preferable. Here, the main monomer refers to a component that accounts for more than 50% by weight of the monomer composition in the monomer raw material.

As the alkyl (meth)acrylate, for example, a compound represented by the following formula (1) can be preferably used.
_CH2 =C( ^R1 ) ^COOR2 (1)
Here, R ¹ in the above formula (1) is a hydrogen atom or a methyl group. R ² is a chain alkyl group having 1 to 20 carbon atoms. Hereinafter, such a carbon atom number range may be expressed as "C1-20". From the viewpoint of the storage modulus of the pressure-sensitive adhesive, it is appropriate to use alkyl (meth)acrylate, in which R ² is a C1-14 (eg, C1-10) chain alkyl group, as the main monomer. From the viewpoint of adhesion properties, it is preferable to use an alkyl acrylate in which R ¹ is a hydrogen atom and R ² is a C4-8 chain alkyl group (hereinafter also simply referred to as C4-8 alkyl acrylate) as the main monomer. .

In some preferred embodiments, as the acrylic polymer, a monomer containing an alkyl (meth)acrylate having an alkyl group having 5 or more carbon atoms at the ester end (hereinafter also referred to as "C5 or higher alkyl (meth)acrylate"). Polymerization of the components is used. The C5 or higher alkyl (meth)acrylate can also be represented by formula (1).
_CH2 =C( ^R1 ) ^COOR2 (1)
Here, R ¹ in the above formula (1) is a hydrogen atom or a methyl group. Also, R ² is a chain alkyl group having 5 or more carbon atoms. By using an acrylic polymer containing a C5 or higher alkyl (meth)acrylate as a monomer component, it is easy to obtain sufficient adhesive strength, the wettability of the adhesive surface is improved, and the acidity from the edge surface of the adhesive sheet to the adhesive interface is improved. Penetration of liquids and alkaline liquids is preferably suppressed. The number of carbon atoms in the alkyl group of the C5 or higher alkyl (meth)acrylate is typically 5 or more and 20 or less. The number of carbon atoms in the alkyl group of the alkyl (meth)acrylate may be, for example, 18 or less, and is suitably 14 or less, preferably 12 or less, more preferably 12 or less from the viewpoint of the storage elastic modulus of the adhesive. It is 10 or less (for example, 9 or less). The number of carbon atoms may be 6 or more, 7 or more, and typically 8.

Specific examples of C5 or higher alkyl (meth)acrylates are not particularly limited, and include pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. , octyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, eicosyl (meth)acrylate and the like. . The above alkyl (meth)acrylates may be used singly or in combination of two or more. A preferred example of the alkyl (meth)acrylate is 2-ethylhexyl acrylate (2EHA).

The ratio of the C5 or higher alkyl (meth)acrylate to the monomer components constituting the acrylic polymer is not particularly limited, and can be, for example, more than 30% by weight or more than 50% by weight, and is 60% by weight or more. is appropriate. Thereby, the effect of using the C5 or higher alkyl (meth)acrylate can be exhibited. The proportion of the C5 or higher alkyl (meth)acrylate is suitably 65% by weight or more, preferably 70% by weight or more (for example, more than 70% by weight), and may be 75% by weight or more. The upper limit of the ratio of the C5 or higher alkyl (meth)acrylate is set in consideration of the properties (e.g., cohesion) based on the submonomer described later, and is preferably 95% by weight or less. etc., it may be 93.5% by weight or less, preferably 90% by weight or less, more preferably 85% by weight or less, for example, 80% by weight or less.

In some embodiments, the acrylic polymer contains, as a monomer component, one or two alkyl (meth)acrylates (C1-4 alkyl (meth)acrylates) having an alkyl group having 4 or less carbon atoms at the ester end. Includes more than one species. Specific examples of C1-4 alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, ) acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate and the like.

In some aspects, C5 in the total alkyl (meth)acrylate having a chain alkyl group at the ester end (hereinafter also simply referred to as "alkyl (meth)acrylate") contained as a monomer component of the acrylic polymer The ratio of the above alkyl (meth)acrylate is, for example, more than 50% by weight, suitably 60% by weight or more, and may be 70% by weight or more. In some preferred embodiments, the ratio of the C5 or higher alkyl (meth)acrylate to the total alkyl (meth)acrylate is more than 70% by weight, and the effect of using the C5 or higher alkyl (meth)acrylate is effectively exhibited. From a viewpoint, it is preferably 80% by weight or more, more preferably 90% by weight or more, and still more preferably 95% by weight or more (for example, 99% by weight or more). The upper limit of the ratio of the C5 or higher alkyl (meth)acrylate in the total alkyl (meth)acrylate is 100% by weight, for example, it may be 95% by weight or less, or may be 90% by weight or less.

It is preferable that a secondary monomer is copolymerized with the acrylic polymer in the technology disclosed herein. A carboxyl group-containing monomer, a hydroxyl group (OH group)-containing monomer, an acid anhydride group-containing monomer, and an amide group are used as sub-monomers that can introduce a functional group that can serve as a cross-linking base point into the acrylic polymer or that can contribute to the improvement of adhesive strength. containing monomers, amino group-containing monomers, epoxy group-containing monomers, cyano group-containing monomers, keto group-containing monomers, nitrogen atom-containing ring-containing monomers, alkoxysilyl group-containing monomers, imide group-containing monomers, and the like. The said submonomer can be used individually by 1 type or in combination of 2 or more types.

When the monomer component constituting the acrylic polymer contains the functional group-containing monomer described above, the content of the functional group-containing monomer in the monomer component is not particularly limited. From the viewpoint of appropriately exhibiting the effect of using the functional group-containing monomer, the content of the functional group-containing monomer in the monomer component can be, for example, 0.1% by weight or more, and should be 0.5% by weight or more. is suitable, and it may be 1% by weight or more. In addition, from the viewpoint of easily balancing the adhesion performance in relation to the main monomer, the content of the functional group-containing monomer in the monomer component is, for example, less than 50% by weight, and is preferably 40% by weight or less. , is preferably 20% by weight or less, and may be 10% by weight or less (for example, 5% by weight or less).

In some preferred embodiments, the monomer component constituting the acrylic polymer is at least one selected from monomers having a nitrogen atom-containing ring (hereinafter also referred to as "N ring-containing monomer") and carboxy group-containing monomers ( preferably both) monomers as sub-monomers. By using an N ring-containing monomer and a carboxyl group-containing monomer as the monomer components, preferably by using both together, the cohesive force of the pressure-sensitive adhesive is improved. A pressure-sensitive adhesive that prevents or suppresses permeation of an alkaline liquid into the pressure-sensitive adhesive can be preferably obtained.

An N-ring-containing monomer refers to a monomer having a polymerizable group and a nitrogen atom-containing ring. Polymerizable groups include (meth)acryloyl groups and vinyl groups. A nitrogen atom-containing ring refers to a cyclic structure containing a nitrogen atom (N) as an atom constituting the ring. The nitrogen atom-containing ring usually has a heterocyclic structure containing a nitrogen atom (N) and a carbon atom (C) as ring-constituting atoms, and further preferably contains an oxygen atom (O) as a ring-constituting atom. Used. Examples of the nitrogen atom-containing ring include lactam structures such as pyrrolidone, morpholine ring, piperidine ring, pyrrolidine ring, piperazine ring, pyridine ring, piperidone ring, pyrimidine ring, pyrazine ring, pyrrole ring, imidazole ring, oxazole ring, etc. Among them, a lactam structure and a morpholine ring are preferred, and a morpholine ring is particularly preferred. The N-ring-containing monomers can be used singly or in combination of two or more.

Examples of N-ring-containing monomers include lactam vinyl monomers such as N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, and N-vinyl-ε-caprolactam; vinylpyridine; vinylpiperidone; vinylpyrimidine; vinylpiperazine; vinylpyrrole; vinylimidazole; vinyloxazole; vinylmorpholine; N-(meth)acryloylmorpholine; N-(meth)acryloylpiperidine; N-(meth)acryloylpyrrolidine; Among them, lactam vinyl monomers and N-(meth)acryloylmorpholine are preferred, and N-vinyl-2-pyrrolidone (NVP) and N-acryloylmorpholine (ACMO) are more preferred. The use of NVP tends to result in a higher adhesive strength, while the use of ACMO tends to achieve both adhesive strength and cohesive strength in a well-balanced manner.

The amount of the N-ring-containing monomer used is not particularly limited. The content of the N-ring-containing monomer may be, for example, 1% by weight or more of the total monomer components, suitably 5% by weight or more, preferably 10% by weight or more, and more preferably 16% by weight or more. , more preferably 20% by weight or more, particularly preferably 22% by weight or more, and may be 28% by weight or more (for example, 32% by weight or more). As the amount of the N-ring-containing monomer used increases, the cohesive force is improved, and the permeation of the acidic liquid and the alkaline liquid into the pressure-sensitive adhesive can be preferably prevented. In addition, the content of the N-ring-containing monomer can be, for example, less than 50% by weight of the total monomer components, and is suitably 40% by weight or less, and may be 35% by weight or less, or 30% by weight. % or less. By limiting the amount of the N-ring-containing monomer to be used within an appropriate range, it is easy to achieve both adhesive strength and cohesive strength.

In addition, by using a carboxy group-containing monomer as a monomer component, it becomes easier to obtain a pressure-sensitive adhesive sheet exhibiting good adhesive properties (cohesion, etc.), which is advantageous for improving the adhesion between the pressure-sensitive adhesive layer and the adherend. obtain. Also, the acid resistance of the adhesive tends to be improved. Furthermore, in an embodiment in which a black colorant such as carbon black is blended into the adhesive, by copolymerizing an appropriate amount of a carboxy group-containing monomer, the colorant can be easily dispersed well in the layer, and the adhesive properties can be improved. can be maintained.

Examples of the carboxy group-containing monomer include acrylic acid (AA), methacrylic acid (MAA), carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid. can be Among them, AA and MAA are preferable. A carboxy group-containing monomer can be used individually by 1 type or in combination of 2 or more types.

The content of the carboxy group-containing monomer in the monomer component is not particularly limited. The carboxy group-containing monomer can be, for example, 0.1% by weight or more (e.g., 0.2% by weight or more, typically 0.5% by weight or more) of the monomer component, and 1% by weight or more. is preferably 1.5% by weight or more, more preferably 2.0% by weight or more, and still more preferably 2.5% by weight or more. A higher effect is exhibited by increasing the content of the carboxy group-containing monomer. The upper limit of the content of the carboxy group-containing monomer is not particularly limited, and can be, for example, 15% by weight or less or 10% by weight or less, suitably 7% by weight or less, preferably 5% by weight or less, It is more preferably 4.5% by weight or less, still more preferably 4.0% by weight or less, and may be, for example, 3.5% by weight or less.

In embodiments in which the monomer component contains at least one of an N-ring-containing monomer and a carboxy-group-containing monomer, the total ratio of the N-ring-containing monomer and the carboxy-group-containing monomer in the monomer component is not particularly limited. % by weight or less, preferably 6.5% by weight or more and 40% by weight or less. By appropriately setting the total amount of the N-ring-containing monomer and the carboxy group-containing monomer, a pressure-sensitive adhesive that has sufficient adhesive strength, improves cohesive strength, and is suitable for preventing permeation of acidic liquids and alkaline liquids can be obtained. can be preferably obtained. In some preferred embodiments, the total proportion of N-ring-containing monomers and carboxy-group-containing monomers in the monomer component is 8% by weight or more, more preferably 12% by weight or more, even more preferably 15% by weight or more, especially It is preferably 18% by weight or more, may be 21% by weight or more, may be 23% by weight or more, or may be 26% by weight or more. Also, the total proportion of the N-ring-containing monomer and the carboxy group-containing monomer in the monomer component is suitably 36% by weight or less, preferably 32% by weight or less, and may be 30% by weight or less. By limiting the total amount of the N-ring-containing monomer and the carboxy group-containing monomer to be used within an appropriate range, both adhesive strength and cohesive strength can be improved.

In the aspect in which the monomer component contains the N-ring-containing monomer and the carboxy-group-containing monomer, the ratio of the N-ring-containing monomer and the carboxy-group-containing monomer is set within a range in which the technique disclosed herein exhibits the effect. In some embodiments, the ratio (A _N /A _C ) of the content of N ring-containing monomers (A _N ) to the content of carboxy group-containing monomers (A _C ) used as monomer components is 1 on a weight basis. ∼40. By appropriately setting the usage ratio of the N-ring-containing monomer and the carboxy group-containing monomer within the above range, a pressure-sensitive adhesive that has sufficient adhesive strength and is suitable for preventing permeation of acidic liquids and alkaline liquids can be preferably obtained. can be done. The ratio (A _N /A _C ) is preferably 3 or more, more preferably 5 or more, still more preferably 7 or more, and 8 or more, from the viewpoint of effectively exhibiting the effect of using the N-ring-containing monomer. good too. In addition, the ratio (A _N /A _C ) is preferably 30 or less, more preferably 25 or less, still more preferably 20 or less, and particularly preferably 15 or less, from the viewpoint of effectively exhibiting the effect of using the carboxy group-containing monomer. and may be 10 or less.

In some embodiments, the monomer component can include hydroxyl-containing monomers. By using a hydroxyl group-containing monomer, the cohesive force and crosslink density of the pressure-sensitive adhesive can be adjusted, and the adhesive force and cohesive force can be adjusted within a preferred range. Examples of hydroxyl-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, ) hydroxyalkyl (meth)acrylate such as acrylate; polypropylene glycol mono(meth)acrylate; N-hydroxyethyl (meth)acrylamide and the like. Among them, preferred hydroxyl group-containing monomers include hydroxyalkyl (meth)acrylates in which the alkyl group is linear and has 2 to 4 carbon atoms. A hydroxyl-containing monomer can be used individually by 1 type or in combination of 2 or more types.

The monomer component may or may not contain a hydroxyl group-containing monomer. In some embodiments, the content of the hydroxyl group-containing monomer is, for example, less than 15% by weight of the total monomer components, suitably 10% by weight or less, and may be 8% by weight or less, or 5% by weight. or less, or 3% by weight or less. According to the technology disclosed herein, a desired effect can be achieved with or without using a small amount of a hydroxyl group-containing monomer. In some preferred embodiments, the amount of hydroxyl-containing monomer is less than 2 wt% of the total monomer component, and may be less than 1.0 wt%, less than 0.5 wt%, or less than 0.3 wt%. good. In addition, when using a hydroxyl group-containing monomer, the amount used is not particularly limited, and the content of the hydroxyl group-containing monomer may be, for example, 0.01% by weight or more, or may be 0.03% by weight or more of the total monomer component. , 0.05% by weight or more, or 0.1% by weight or more.

In some embodiments, the monomer component that constitutes the acrylic polymer is, among the above-described submonomers (typically, functional group-containing monomers), submonomers other than N-ring-containing monomers, carboxyl-containing monomers, and hydroxyl-containing monomers. It may or may not contain one or two or more monomers (other submonomers). In addition, the amount of the other submonomer is not particularly limited, and may be appropriately selected according to the purpose and application. The content of other submonomers in the monomer component is, for example, suitably less than 30% by weight, preferably less than 10% by weight, more preferably less than 5% by weight, and less than 3% by weight (for example, less than 1% by weight). The technology disclosed herein can also be preferably practiced in a mode in which the monomer component does not substantially contain other sub-monomers. Here, the monomer component does not substantially contain other sub-monomers means that other sub-monomers are not used at least intentionally. Intentional inclusion is acceptable.

The monomer components constituting the acrylic polymer may contain copolymer components other than the sub-monomers described above for the purpose of improving the cohesive force and the like. Examples of other copolymerization components include vinyl ester monomers such as vinyl acetate, vinyl propionate, and vinyl laurate; aromatic vinyl compounds such as styrene, substituted styrene (α-methylstyrene, etc.) and vinyltoluene; Cycloalkyl (meth)acrylates such as meth)acrylate, cyclopentyl (meth)acrylate, isobornyl (meth)acrylate; aryl (meth)acrylates (e.g. phenyl (meth)acrylate), aryloxyalkyl (meth)acrylates (e.g. phenoxyethyl ( aromatic ring-containing (meth)acrylates such as arylalkyl (meth)acrylates (e.g., benzyl (meth)acrylate); olefinic monomers such as ethylene, propylene, isoprene, butadiene, and isobutylene; vinyl chloride, chloride Chlorine-containing monomers such as vinylidene; isocyanate group-containing monomers such as 2-(meth)acryloyloxyethyl isocyanate; alkoxy group-containing monomers such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate; Vinyl ether-based monomer; 2 or more (eg, 3 or more) polymerizable functional groups (eg, (meth)acryloyl group) in one molecule, such as 1,6-hexanediol di(meth)acrylate and trimethylolpropane tri(meth)acrylate ), and the like.

The monomer component that constitutes the acrylic polymer may or may not contain the other copolymer component. In addition, the amount of the copolymerizable monomer of the other copolymerization component may be appropriately selected depending on the purpose and application, and is not particularly limited. The content of other copolymerization components in the monomer component is, for example, suitably less than 30% by weight, preferably less than 10% by weight, more preferably less than 5% by weight, and less than 3% by weight ( For example, less than 1% by weight). The technology disclosed herein can also be preferably practiced in a mode in which the monomer component does not substantially contain other copolymerization components. Here, the monomer component does not substantially contain other copolymerization components means that other copolymerization components are not used at least intentionally, and other copolymerization components are, for example, 0.01 wt% or less. To some extent, unintentional inclusion is acceptable.

The method for obtaining an acrylic polymer is not particularly limited, and various known methods for synthesizing an acrylic polymer, such as solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization, and photopolymerization, can be used. Any suitable polymerization method can be employed. For example, a solution polymerization method can be preferably employed. The polymerization temperature at the time of solution polymerization can be appropriately selected according to the type of monomer and solvent used, the type of polymerization initiator, etc. ° C.).

The solvent (polymerization solvent) used for solution polymerization can be appropriately selected from conventionally known organic solvents (toluene, ethyl acetate, etc.). Depending on the type of polymerization method, the initiator used for polymerization may be a conventionally known polymerization initiator (for example, an azo polymerization initiator such as 2,2'-azobisisobutyronitrile (AIBN) or a peroxide polymerization initiator). initiator, etc.). The amount of the polymerization initiator used may be a normal amount, for example, about 0.005 to 1 part by weight (typically about 0.01 to 1 part by weight) per 100 parts by weight of the monomer component. ).

The molecular weight of the acrylic polymer obtained by appropriately adopting the various polymerization methods described above is not particularly limited, and can be set within an appropriate range according to the required performance and the like. In some embodiments, the weight average molecular weight (Mw) of the polymer can range from approximately 10×10 ⁴ to 500×10 ⁴ . From the viewpoint of achieving both adhesive strength and cohesive strength in a well-balanced manner, the above Mw is suitably about 30×10 ⁴ or more, and from the viewpoint of adhesion reliability, it is preferably about 50×10 4 or more, more preferably about 50×10 ⁴ or more. is approximately 70×10 ⁴ or more, more preferably approximately 90×10 ⁴ or more, and may be greater than 100×10 ⁴ . The upper limit of Mw of the polymer may be about 300×10 ⁴ or less, or about 200×10 ⁴ or less (for example, about 150×10 ⁴ or less). For example, Mw in the above range can be preferably employed as Mw of the polymer obtained by solution polymerization. Here, Mw refers to a value converted to standard polystyrene obtained by GPC (gel permeation chromatography). As the GPC apparatus, for example, model name "HLC-8320GPC" (column: TSKgelGMH-H(S), manufactured by Tosoh Corporation) can be used. The same applies to the examples described later.

(tackifying resin)
The pressure-sensitive adhesive layer can contain a tackifying resin. Thereby, the adhesive strength of an adhesive sheet can be improved. Examples of tackifying resins include rosin-based tackifying resins, phenol-based tackifying resins, terpene-based tackifying resins, modified terpene-based tackifying resins, hydrocarbon-based tackifying resins, epoxy-based tackifying resins, polyamide-based tackifying resins, One or more selected from various known tackifier resins such as elastomer-based tackifier resins and ketone-based tackifier resins can be used. For example, rosin-based tackifying resins, phenol-based tackifying resins, terpene-based tackifying resins, modified terpene-based tackifying resins, and hydrocarbon-based tackifying resins are preferred, and rosin-based tackifying resins are more preferred.

Specific examples of rosin-based tackifying resins include unmodified rosins (fresh rosins) such as gum rosin, wood rosin and tall oil rosin; hydrogenated rosin, disproportionated rosin, polymerized rosin, other chemically modified rosin, etc. (same below); other various rosin derivatives; Examples of the rosin derivative include rosins obtained by esterifying unmodified rosin with alcohols (that is, esterified rosin), and esterifying modified rosin with alcohols (that is, esterified rosin). Esters; Undenatured rosin and rosins modified with unsaturated fatty acids obtained by modifying rosin with unsaturated fatty acids; Rosin esters modified with unsaturated fatty acids obtained by modifying rosin esters with unsaturated fatty acids; Unmodified rosin, modified rosin, unsaturated Rosin alcohols obtained by reducing the carboxy group in fatty acid-modified rosins or unsaturated fatty acid-modified rosin esters; metal salts of rosins (especially rosin esters) such as unmodified rosin, modified rosin, and various rosin derivatives; rosins rosin phenol resin obtained by adding phenol to (unmodified rosin, modified rosin, various rosin derivatives, etc.) with an acid catalyst and thermally polymerizing; and the like. Specific examples of rosin esters include, but are not limited to, esters of unmodified rosin or modified rosin (hydrogenated rosin, disproportionated rosin, polymerized rosin, etc.), such as methyl ester, triethylene glycol ester, and glycerin ester. , pentaerythritol ester and the like. Among them, rosin ester is preferred. Rosin-based tackifying resins can be used singly or in combination of two or more.

Examples of phenolic tackifying resins include terpene phenolic resins, hydrogenated terpene phenolic resins and alkylphenolic resins.
Terpene phenol resin refers to a polymer containing a terpene residue and a phenol residue, a copolymer of terpenes and a phenol compound (terpene-phenol copolymer resin), and a homopolymer or copolymer of terpenes is a concept that includes both phenol-modified (phenol-modified terpene resin). Preferred examples of terpenes constituting such a terpene phenol resin include monoterpenes such as α-pinene, β-pinene, and limonene (including d-, l- and d/l-forms (dipentene)). is mentioned. A hydrogenated terpene phenol resin refers to a hydrogenated terpene phenol resin having a structure obtained by hydrogenating such a terpene phenol resin. It is sometimes called a hydrogenated terpene phenolic resin.
Alkylphenol resins are resins obtained from alkylphenols and formaldehyde (oily phenolic resins). Examples of alkylphenol resins include novolac and resole types.

Examples of terpene-based tackifying resins include polymers of terpenes (typically monoterpenes) such as α-pinene, β-pinene, d-limonene, l-limonene and dipentene. It may be a homopolymer of one kind of terpenes, or a copolymer of two or more kinds of terpenes. One type of terpene homopolymer includes α-pinene polymer, β-pinene polymer, dipentene polymer and the like. Examples of modified terpene resins include those obtained by modifying the above terpene resins. Specific examples include styrene-modified terpene resins and hydrogenated terpene resins.

Examples of hydrocarbon tackifying resins include aliphatic hydrocarbon resins, aromatic hydrocarbon resins, aliphatic cyclic hydrocarbon resins, aliphatic/aromatic petroleum resins (styrene-olefin copolymers, etc. ), aliphatic/alicyclic petroleum resins, hydrogenated hydrocarbon resins, coumarone-based resins, and coumarone-indene-based resins.

Suitable examples of tackifying resins include rosin-based tackifying resins. Among them, rosin ester is preferably used. The proportion of the rosin-based tackifying resin in the total tackifying resin contained in the pressure-sensitive adhesive layer may be, for example, more than about 50% by weight, may be about 70% by weight or more, or may be about 80% by weight or more. . In the technology disclosed herein, substantially all of the tackifying resin (for example, approximately 97% by weight or more, or 99% by weight or more, or even 100% by weight) is preferably a rosin-based tackifying resin. can be implemented.

The softening point of the tackifying resin is not particularly limited. The softening point of the tackifier resin may be, for example, approximately 50° C. or higher, preferably approximately 60° C. or higher, or approximately 70° C. or higher, from the viewpoint of exhibiting an appropriate cohesive force. There is no particular upper limit for the softening point of the tackifying resin. From the viewpoint of improving adhesion to adherends, in some embodiments, a tackifying resin having a softening point of approximately 200° C. or lower (more preferably approximately 150° C. or lower, for example, less than 130° C.) can be preferably used.

In some preferred embodiments, the tackifying resin comprises a tackifying resin T _L having a softening point of 110° C. or less. By using the tackifying resin _TL , the adhesion to the adherend (initial adhesion, etc.) is improved, it becomes easier to obtain good adhesive strength, and the infiltration of acidic liquids and alkaline liquids into the adhesion interface is prevented. It's easy to do. The softening point of the tackifier resin T _L is suitably less than 110°C, preferably about 105°C or less, more preferably about 100°C or less, even more preferably about 95°C or less (e.g., less than 95°C), Particularly preferably, it is about 90° C. or lower (for example, about 85° C. or lower). The lower limit of the softening point of the tackifier resin T _L is not particularly limited, and in some embodiments, the softening point of the tackifier resin T _L is, for example, about 50° C. or higher from the viewpoint of exhibiting an appropriate cohesive force. Well, it may be about 60° C. or higher, about 65° C. or higher, or about 70° C. or higher.

Examples of rosin-based tackifying resins that can be preferably employed as the tackifying resin _TL include, but are not particularly limited to, rosin esters such as unmodified rosin esters and modified rosin esters. Preferred examples of modified rosin esters include hydrogenated rosin esters. For example, esters of unmodified rosin or modified rosin (eg, hydrogenated rosin), eg, rosin esters such as methyl esters, glycerin esters, etc., can be used as tackifying resins T _L . In some preferred embodiments of the pressure-sensitive adhesive layer, the tackifying resin _TL comprises a hydrogenated rosin ester. The tackifying resin _TL may contain only one or more hydrogenated rosin esters as rosin esters.

The tackifier resin _TL may contain other tackifier resins in addition to the rosin-based tackifier resin. As the other tackifying resin, one selected from those having a softening point of 110° C. or lower among the tackifying resins exemplified above can be used alone or in combination of two or more.

In some embodiments, the proportion of the rosin-based tackifying resin in the total tackifying resin T _L can be, for example, approximately greater than 50% by weight, may be approximately 65% by weight or greater, or approximately 75% by weight or greater. good too. The technology disclosed herein is an aspect in which substantially all of the tackifying resin T _L (for example, about 97% by weight or more, or 99% by weight or more, or even 100% by weight) is a rosin-based tackifying resin. can be preferably implemented in

The adhesive layer may or may not contain the tackifying resin _TL . In addition, the amount of tackifier resin _TL used (the total amount when two or more tackifier resins are included) is set so that the effect of the technology disclosed herein can be exhibited. The content of the tackifier resin T _L in the adhesive layer can be appropriately set, for example, in the range of about 60 parts by weight or less with respect to 100 parts by weight of the acrylic polymer, and from the viewpoint of cohesive strength, etc., it is 50 parts by weight. parts by weight or less is suitable, preferably 45 parts by weight or less, more preferably 40 parts by weight or less, and may be 35 parts by weight or less. In the embodiment in which the pressure-sensitive adhesive layer contains the tackifying resin T _L , the amount of the tackifying resin T _L used with respect to 100 parts by weight of the acrylic polymer is about 1 part by weight or more so that the effect of containing the tackifying resin T _L is exhibited. In some preferred embodiments, from the viewpoint of improving adhesive strength, it is suitable to be 5 parts by weight or more, may be 10 parts by weight or more, or even 15 parts by weight or more Well, it may be 20 parts by weight or more, or 25 parts by weight or more. In some other embodiments, the adhesive layer is substantially free of tackifying resin T _L . In this embodiment, it is permissible for the pressure-sensitive adhesive layer to contain about 0.3% by weight or less (eg, 0.1% by weight or less, typically 0.01% by weight or less) of the tackifier resin T _L .

In some embodiments, the pressure-sensitive adhesive layer comprises a tackifying resin T _L having a softening point of 110° C. or lower and a tackifying resin T having a softening point higher than 110° C. (typically higher than 110° C. and 200° C. or lower). _H in combination. By using the tackifying resin T _L and the tackifying resin T _H together, it is easy to achieve higher adhesive strength. As the tackifying resin _TH , among the tackifying resins exemplified above, those having a softening point of over 110° C. can be used singly or in combination of two or more. The tackifying resin _TH preferably contains one or more selected from rosin-based tackifying resins. More preferably, both the tackifying resin T _L and the tackifying resin T _H contain a rosin-based tackifying resin.

The softening point of the tackifier resin _TH may be about 115° C. or higher, about 120° C. or higher, about 130° C. or higher, or about 140° C. or higher, from the viewpoint of improving the cohesive strength. The upper limit of the softening point of the tackifying resin T _H is not particularly limited, and from the viewpoint of adhesion to the adherend, the softening point is about 200 ° C. or lower (more preferably about 160 ° C. or lower, further preferably 145 ° C. or lower, for example about 130° C. or less) can be preferably used.

The adhesive layer may or may not contain the tackifying resin _TH . In addition, the amount of tackifier resin _TH used (the total amount when two or more tackifier resins are included) is set so that the effect of the technique disclosed herein is exhibited. The content of the tackifying resin _TH in the adhesive layer is, for example, suitably less than 30 parts by weight, preferably less than 20 parts by weight, and 18 parts by weight with respect to 100 parts by weight of the acrylic polymer. It may be below. In the embodiment in which the pressure-sensitive adhesive layer contains the tackifying resin T _H , the amount of the tackifying resin T _H used with respect to 100 parts by weight of the acrylic polymer is about 1 part by weight or more so that the effect of containing the tackifying resin T _H is exhibited. In some embodiments, from the viewpoint of improving adhesive strength, it is suitable to be 5 parts by weight or more, may be 10 parts by weight or more, or may be 12 parts by weight or more . The technology disclosed herein can also be preferably practiced in a mode in which the pressure-sensitive adhesive layer does not substantially contain the tackifying resin _TH .

The softening point of the tackifying resin as used herein is defined as a value measured based on the softening point test method (ring and ball method) specified in JIS K5902 and JIS K2207. Specifically, the sample is melted as quickly as possible at the lowest possible temperature and carefully filled into a ring placed on a flat metal plate to avoid the formation of bubbles. After it cools down, cut off the raised part from the plane including the top of the ring with a slightly heated knife. Next, a supporter (ring base) is placed in a glass container (heating bath) having a diameter of 85 mm or more and a height of 127 mm or more, and glycerin is poured to a depth of 90 mm or more. Next, the steel ball (diameter 9.5 mm, weight 3.5 g) and the ring filled with the sample are immersed in the glycerin without touching each other, and the temperature of the glycerin is kept at 20° C.±5° C. for 15 minutes. . A steel ball is then centered on the surface of the sample in the ring and placed in position on the support. Next, the distance from the upper end of the ring to the glycerin surface is kept at 50 mm, a thermometer is placed, the center of the mercury ball of the thermometer is set at the same height as the center of the ring, and the container is heated. The Bunsen burner flame used for heating is directed halfway between the center and the rim of the bottom of the vessel to ensure even heating. The rate at which the bath temperature rises after reaching 40° C. from the start of heating must be 5.0±0.5° C. per minute. The temperature at which the sample gradually softens and flows down the ring and finally touches the bottom plate is read and taken as the softening point. Two or more softening points are measured at the same time, and the average value is adopted.

The technology disclosed herein can be implemented in either a mode in which the pressure-sensitive adhesive layer contains a tackifying resin or a mode in which the pressure-sensitive adhesive layer does not contain a tackifying resin. The amount of the tackifier resin used (the total amount (total amount) when two or more tackifier resins are included) is set so that the effect of the technology disclosed herein is exhibited. The content of the tackifying resin in the pressure-sensitive adhesive layer can be appropriately set, for example, in the range of about 100 parts by weight or less with respect to 100 parts by weight of the acrylic polymer, and from the viewpoint of cohesive strength, etc., it is 60 parts by weight or less. and preferably 50 parts by weight or less (for example, 40 parts by weight or less). In the embodiment in which the pressure-sensitive adhesive layer contains a tackifying resin, the content of the tackifying resin with respect to 100 parts by weight of the acrylic polymer is suitably about 1 part by weight or more so that the effect of containing the tackifying resin is exhibited. In some preferred embodiments, from the viewpoint of improving adhesive strength, etc., it is appropriate to use 5 parts by weight or more, preferably 10 parts by weight or more, may be 15 parts by weight or more, or 20 parts by weight. or more, or 25 parts by weight or more. In some other embodiments, the adhesive layer is substantially free of tackifying resin. In this embodiment, it is permissible for the pressure-sensitive adhesive layer to contain about 0.3% by weight or less (eg, 0.1% by weight or less, typically 0.01% by weight or less) of the tackifying resin.

(crosslinking agent)
In the technique disclosed here, the adhesive composition used for forming the adhesive layer may contain a cross-linking agent as needed. By using an appropriate type and amount of cross-linking agent for other components (acrylic polymers, tackifying resins, etc.) in the adhesive layer, the properties of the adhesive can be adjusted to provide an adhesive with desired properties. agent can be preferably realized. The type of cross-linking agent is not particularly limited, and can be appropriately selected from conventionally known cross-linking agents. Examples of such cross-linking agents include isocyanate-based cross-linking agents, epoxy-based cross-linking agents, oxazoline-based cross-linking agents, aziridine-based cross-linking agents, melamine-based cross-linking agents, peroxide-based cross-linking agents, urea-based cross-linking agents, and metal alkoxide-based cross-linking agents. Cross-linking agents, metal chelate-based cross-linking agents, metal salt-based cross-linking agents, carbodiimide-based cross-linking agents, hydrazine-based cross-linking agents, amine-based cross-linking agents, silane coupling agents, and the like. Among them, isocyanate-based cross-linking agents, epoxy-based cross-linking agents, oxazoline-based cross-linking agents, aziridine-based cross-linking agents, and melamine-based cross-linking agents are preferable, and isocyanate-based cross-linking agents and epoxy-based cross-linking agents are more preferable. A crosslinking agent can be used individually by 1 type or in combination of 2 or more types. The cross-linking agent is contained in the pressure-sensitive adhesive layer in the form after the cross-linking reaction, the form before the cross-linking reaction, the form in which the cross-linking reaction is partially performed, the intermediate or composite form thereof, and the like. The cross-linking agent is typically contained in the pressure-sensitive adhesive layer exclusively in the form after the cross-linking reaction.

In some preferred embodiments, an isocyanate-based cross-linking agent is used as the cross-linking agent. As the isocyanate-based cross-linking agent, a polyfunctional isocyanate (meaning a compound having an average of two or more isocyanate groups per molecule, including those having an isocyanurate structure) can be preferably used. The isocyanate-based cross-linking agents may be used singly or in combination of two or more.

Examples of polyfunctional isocyanates include aliphatic polyisocyanates, alicyclic polyisocyanates, and aromatic polyisocyanates.
Specific examples of aliphatic polyisocyanates include 1,2-ethylene diisocyanate; tetramethylene diisocyanates such as 1,2-tetramethylene diisocyanate, 1,3-tetramethylene diisocyanate and 1,4-tetramethylene diisocyanate; - hexamethylene diisocyanates such as hexamethylene diisocyanate, 1,3-hexamethylene diisocyanate, 1,4-hexamethylene diisocyanate, 1,5-hexamethylene diisocyanate, 1,6-hexamethylene diisocyanate, 2,5-hexamethylene diisocyanate; 2-methyl-1,5-pentane diisocyanate, 3-methyl-1,5-pentane diisocyanate, lysine diisocyanate and the like.

Specific examples of alicyclic polyisocyanates include isophorone diisocyanate; cyclohexyl diisocyanates such as 1,2-cyclohexyl diisocyanate, 1,3-cyclohexyl diisocyanate and 1,4-cyclohexyl diisocyanate; 1,2-cyclopentyl diisocyanate, 1,3 - cyclopentyl diisocyanate such as cyclopentyl diisocyanate; hydrogenated xylylene diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated tetramethylxylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate and the like.

Specific examples of aromatic polyisocyanates include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, and 2,2'-diphenylmethane diisocyanate. , 4,4′-diphenyl ether diisocyanate, 2-nitrodiphenyl-4,4′-diisocyanate, 2,2′-diphenylpropane-4,4′-diisocyanate, 3,3′-dimethyldiphenylmethane-4,4′-diisocyanate , 4,4′-diphenylpropane diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, naphthylene-1,4-diisocyanate, naphthylene-1,5-diisocyanate, 3,3′-dimethoxydiphenyl-4,4′-diisocyanate , xylylene-1,4-diisocyanate, xylylene-1,3-diisocyanate, and the like.

Examples of preferred polyfunctional isocyanates include polyfunctional isocyanates having an average of 3 or more isocyanate groups per molecule. Such tri- or more functional isocyanates are polymers (typically dimers or trimers) of di- or tri- or more functional isocyanates, derivatives (for example, polyhydric alcohols and two or more molecules of polyfunctional isocyanates). addition reaction products), polymers, and the like. For example, dimers and trimers of diphenylmethane diisocyanate, isocyanurate of hexamethylene diisocyanate (trimer adduct of isocyanurate structure), reaction products of trimethylolpropane and tolylene diisocyanate, trimethylolpropane and hexa Polyfunctional isocyanates such as reaction products with methylene diisocyanate, polymethylene polyphenyl isocyanate, polyether polyisocyanate and polyester polyisocyanate can be mentioned. Commercially available polyfunctional isocyanates include "Duranate TPA-100" (trade name) manufactured by Asahi Kasei Chemicals, "Coronate L" (trade name), "Coronate HL", "Coronate HK" (trade name) and "Coronate HK" (trade names) manufactured by Tosoh Corporation. HX", "Coronate 2096", and the like.

The amount of the isocyanate-based cross-linking agent used is not particularly limited. For example, it can be about 0.5 parts by weight or more with respect to 100 parts by weight of the acrylic polymer. From the viewpoint of compatibility between cohesion and adhesion, impact resistance, etc., the amount of the isocyanate-based cross-linking agent used relative to 100 parts by weight of the acrylic polymer can be, for example, 1.0 parts by weight or more, and 1.5 parts by weight. It may be at least parts by weight (for example, at least 2.0 parts by weight). On the other hand, from the viewpoint of improving the adhesion to the adherend, the amount of the isocyanate-based cross-linking agent used is preferably 10 parts by weight or less with respect to 100 parts by weight of the acrylic polymer, and is 8 parts by weight or less. may be 5 parts by weight or less, or 3 parts by weight or less (for example, less than 3 parts by weight).

Another suitable example of the cross-linking agent is an epoxy-based cross-linking agent. As the epoxy-based cross-linking agent, a compound having two or more epoxy groups in one molecule can be used without particular limitation. An epoxy-based cross-linking agent having 3 to 5 epoxy groups in one molecule is preferred. Epoxy-based cross-linking agents may be used singly or in combination of two or more.

Specific examples of epoxy-based cross-linking agents include, but are not limited to, N,N,N',N'-tetraglycidyl-m-xylenediamine, 1,3-bis(N,N-diglycidylaminomethyl ) cyclohexane, 1,6-hexanediol diglycidyl ether, polyethylene glycol diglycidyl ether, polyglycerol polyglycidyl ether and the like. Commercially available epoxy-based cross-linking agents include Mitsubishi Gas Chemical Co., Ltd.'s trade name "TETRAD-C" and trade name "TETRAD-X", DIC's trade name "Epiclon CR-5L", and Nagase ChemteX Corp. and "TEPIC-G" manufactured by Nissan Chemical Industries, Ltd. under the trade name of "Denacol EX-512".

The amount of the epoxy-based cross-linking agent used is not particularly limited. The amount of the epoxy-based cross-linking agent used is, for example, more than 0 parts by weight and about 1 part by weight or less (typically about 0.001 to 0.5 parts by weight) with respect to 100 parts by weight of the acrylic polymer. can do. From the viewpoint of suitably exhibiting the effect of improving the cohesive force, the amount of the epoxy-based cross-linking agent to be used is appropriately about 0.005 parts by weight or more, and about 0.005 parts by weight per 100 parts by weight of the acrylic polymer. 01 parts by weight or more is preferable, about 0.02 parts by weight or more is more preferable, and about 0.03 parts by weight or more is even more preferable. In addition, from the viewpoint of improving the adhesion to the adherend, the amount of the epoxy-based cross-linking agent to be used is appropriately about 0.5 parts by weight or less per 100 parts by weight of the acrylic polymer, and about 0.5 part by weight. It is preferably 2 parts by weight or less, more preferably less than 0.1 parts by weight, and even more preferably 0.07 parts by weight or less (for example, approximately 0.05 parts by weight or less). Impact resistance also tends to be improved by reducing the amount of the epoxy-based cross-linking agent used.

In some preferred embodiments, an isocyanate-based cross-linking agent and at least one cross-linking agent having a different type of cross-linkable functional group from the isocyanate-based cross-linking agent are used in combination as the cross-linking agent. According to the technology disclosed herein, a cross-linking agent other than an isocyanate-based cross-linking agent (that is, a cross-linking agent having a different type of cross-linkable reactive group from the isocyanate-based cross-linking agent; hereinafter also referred to as a "non-isocyanate cross-linking agent"). Excellent cohesion can be exhibited by using it in combination with an isocyanate-based cross-linking agent.

The type of non-isocyanate cross-linking agent that can be used in combination with the isocyanate cross-linking agent is not particularly limited, and can be appropriately selected from the cross-linking agents described above. The non-isocyanate-based cross-linking agents may be used singly or in combination of two or more. In some preferred embodiments, an epoxy-based cross-linking agent can be employed as the non-isocyanate-based cross-linking agent. For example, by using an isocyanate-based cross-linking agent and an epoxy-based cross-linking agent in combination, it is easy to achieve both cohesiveness and impact resistance.

In the technology disclosed herein, the relationship between the content of the isocyanate-based cross-linking agent and the content of the non-isocyanate-based cross-linking agent (eg, epoxy-based cross-linking agent) is not particularly limited. The content of the non-isocyanate cross-linking agent can be, for example, about 1/10 or less of the content of the isocyanate cross-linking agent. From the viewpoint of achieving both adhesion to adherends and cohesion, the content of the non-isocyanate cross-linking agent is about 1/20 or less of the content of the isocyanate cross-linking agent on a weight basis. It is suitable, and preferably about 1/30 or less (for example, 1/40 or less). In addition, from the viewpoint of suitably exhibiting the effect of using a combination of an isocyanate-based cross-linking agent and a non-isocyanate-based cross-linking agent (for example, an epoxy-based cross-linking agent), the content of the non-isocyanate-based cross-linking agent It is suitable to be about 1/1000 or more, for example about 1/500 or more, about 1/300 or more, about 1/100 or more, or about 1/60 or more of the content.

The total amount (total amount) of the cross-linking agent used is not particularly limited. For example, it can be about 10 parts by weight or less per 100 parts by weight of the acrylic polymer, preferably about 0.005 to 10 parts by weight, more preferably about 0.01 to 5 parts by weight. be able to.

(coloring agent)
The pressure-sensitive adhesive layer may or may not contain a coloring agent. The light transmittance (light shielding property) of the pressure-sensitive adhesive layer can be adjusted by including a coloring agent. Adjusting the light transmittance of the pressure-sensitive adhesive layer can also help adjust the light transmittance of the pressure-sensitive adhesive sheet including the pressure-sensitive adhesive layer. As the coloring agent, various materials that can attenuate light traveling through the pressure-sensitive adhesive layer by reflecting and/or absorbing it can be used. The color of the coloring agent is not particularly limited, and may be, for example, black, gray, white, red, blue, yellow, green, yellow-green, orange, purple, gold, silver, pearl color, and the like. The above colorant can typically be contained in the pressure-sensitive adhesive layer in a state of being dispersed (or in a dissolved state) in the constituent materials of the pressure-sensitive adhesive layer.

Various pigments and dyes can be used as the colorant. Examples of pigments include zinc carbonate, zinc oxide, zinc sulfide, talc, kaolin, calcium carbonate, titanium oxide, silica, lithium fluoride, calcium fluoride, barium sulfate, alumina, zirconia, iron oxide, and iron hydroxide. , Chromium oxide type, Spinel type firing type, Chromic acid type, Chromium vermillion type, Prussian blue type, Aluminum powder type, Bronze powder type, Silver powder type, Inorganic pigment such as calcium phosphate, Phthalocyanine type, Azo type, Condensed azo type , azo lake-based, anthraquinone-based, perylene/perinone-based, indigo-based, thioindigo-based, isoindolinone-based, azomethine-based, dioxazine-based, quinacridone-based, aniline black-based, triphenylmethane-based, and carbon black-based organic pigments. be done. Examples of dyes include azo dyes, anthraquinone, quinophthalone, styryl, diphenylmethane, triphenylmethane, oxazine, triazine, xanthan, methane, azomethine, acridine, and diazine. Colorants may be used singly or in appropriate combination of two or more.

A black colorant can be preferably used because the light-shielding property can be efficiently adjusted with a small amount of the colorant. Specific examples of black colorants include carbon black (furnace black, channel black, acetylene black, thermal black, lamp black, pine smoke, etc.), graphite, copper oxide, manganese dioxide, aniline black, perylene black, titanium black, and cyanine. Black, hematite, activated carbon, ferrite (non-magnetic ferrite, magnetic ferrite, etc.), magnetite, chromium oxide, iron oxide, molybdenum disulfide, chromium complexes, anthraquinone colorants, and the like. These can be used individually by 1 type or in combination of 2 or more types as appropriate. Among them, carbon black is preferred. As the carbon black particles, it is also possible to use surface-modified carbon black particles having functional groups such as carboxyl groups, amino groups, sulfonic acid groups, silicon-containing groups (e.g., alkoxysilyl groups and alkylsilyl groups). . Such surface-modified carbon black particles are also called self-dispersing carbon black, and the addition of a dispersant becomes unnecessary or the amount thereof can be reduced. The carbon black particles may be used singly or in combination of two or more.

A particulate coloring agent (pigment) can be preferably used because a small amount of the coloring agent can efficiently adjust the light-shielding property of the pressure-sensitive adhesive layer. In some preferred embodiments, colorants (eg, particulate black colorants such as carbon black) having an average particle size of about 10 nm or greater (eg, approximately 30 nm or greater) can be used. The average particle size is, for example, approximately 50 nm or more, may be approximately 100 nm or more, or may be approximately 150 nm or more. The upper limit of the average particle size of the colorant is not particularly limited, and is, for example, about 3000 nm or less, and may be about 1000 nm or less. From the viewpoint of improving the light-shielding property, the average particle size of the coloring agent is appropriately about 500 nm or less.

The average particle size of the coloring agent in this specification refers to the volume average particle size, and specifically, the integrated value of 50% in the particle size distribution measured based on the particle size distribution measuring device based on the laser scattering/diffraction method. (50% volume average particle diameter; hereinafter sometimes abbreviated as _D50 ). As the measuring device, for example, the product name "Microtrac MT3000II" manufactured by Microtrac Bell Co. or its equivalent can be used.

The content of the coloring agent is not limited to a specific range. From the viewpoint of obtaining the effect of adding the colorant, the content of the colorant in the pressure-sensitive adhesive layer can be approximately 0.1% by weight or more, and is suitably approximately 0.5% by weight or more. From the viewpoint of light-shielding properties, the content is preferably about 1% by weight or more, more preferably about 2% by weight or more, and even more preferably about 3% by weight or more (for example, about 5% by weight or more). In addition, the upper limit of the content of the colorant in the pressure-sensitive adhesive layer can be, for example, less than 15% by weight, suitably less than 10% by weight, preferably less than 8% by weight. More preferably less than % by weight. Limiting the amount of the colorant used in the pressure-sensitive adhesive layer is also preferable from the viewpoint of suppressing deterioration in pressure-sensitive adhesive properties and maintaining the intended performance.

(anti-rust)
The pressure-sensitive adhesive layer according to some preferred embodiments may contain an antirust agent. Rust inhibitors are not particularly limited, and include azole rust inhibitors, amine compounds, nitrites, ammonium benzoate, ammonium phthalate, ammonium stearate, ammonium palmitate, ammonium oleate, ammonium carbonate, and dicyclohexylamine benzoate. acid salts, urea, urotropine, thiourea, phenyl carbamate, cyclohexylammonium-N-cyclohexylcarbamate (CHC) and the like. The rust preventives can be used singly or in combination of two or more.

As the rust preventive agent, an azole rust preventive agent can be preferably used. As the azole-based rust preventive agent, a five-membered ring aromatic compound containing two or more heteroatoms, in which at least one of the heteroatoms is a nitrogen atom, is preferably used as an active ingredient. can be Preferred examples of compounds that can be used as azole rust inhibitors include benzotriazole rust inhibitors containing benzotriazole compounds as active ingredients. Preferable examples of benzotriazole compounds include 1,2,3-benzotriazole, 5-methylbenzotriazole, 4-methylbenzotriazole, carboxybenzotriazole and the like.

The content of the rust inhibitor is not particularly limited, and can be, for example, 0.01 parts by weight or more (typically 0.05 parts by weight or more) with respect to 100 parts by weight of the acrylic polymer. From the viewpoint of obtaining a better metal corrosion prevention effect, the content may be 0.1 parts by weight or more, 0.3 parts by weight or more, or 0.5 parts by weight or more. On the other hand, from the viewpoint of increasing the cohesive strength of the pressure-sensitive adhesive, the content of the rust inhibitor is preferably less than 8 parts by weight with respect to 100 parts by weight of the acrylic polymer, and may be 5 parts by weight or less. It may be 2 parts by weight or less.

(Other additives)
The pressure-sensitive adhesive composition may optionally contain adhesive agents such as leveling agents, cross-linking aids, plasticizers, softeners, fillers, antistatic agents, anti-aging agents, ultraviolet absorbers, antioxidants, light stabilizers, and the like. Various additives common in the pharmaceutical field may be included. In addition, the pressure-sensitive adhesive composition optionally contains a polymer (rubber-based polymer, etc.) or an oligomer (for example, an acrylic-based oligomer having a Mw of about 1000 or more and less than 30000) other than an acrylic polymer within a range that does not impair the effects of the invention. It's okay. As for such various additives, conventionally known ones can be used in a conventional manner, and since they do not particularly characterize the present invention, detailed description thereof will be omitted.

(Adhesive composition)
The pressure-sensitive adhesive layer (layer made of pressure-sensitive adhesive) disclosed herein is a water-based pressure-sensitive adhesive composition, a solvent-based pressure-sensitive adhesive composition, a hot-melt pressure-sensitive adhesive composition, and active energy rays such as ultraviolet rays and electron beams. It may be a pressure-sensitive adhesive layer formed from an active energy ray-curable pressure-sensitive adhesive composition that is cured by irradiation. The water-based pressure-sensitive adhesive composition refers to a pressure-sensitive adhesive composition in the form of containing a pressure-sensitive adhesive (adhesive layer-forming component) in a water-based solvent (aqueous solvent), typically water-dispersed. Also included are so-called type adhesive compositions (compositions in which at least part of the adhesive is dispersed in water) and the like. Moreover, the solvent-type adhesive composition refers to an adhesive composition in the form of containing an adhesive in an organic solvent. As the organic solvent contained in the solvent-based pressure-sensitive adhesive composition, one or two or more of the organic solvents (toluene, ethyl acetate, etc.) exemplified as the organic solvent (toluene, ethyl acetate, etc.) that can be used in the above solution polymerization can be used without particular limitation. From the viewpoint of adhesive properties, the technology disclosed herein can be preferably practiced in a mode comprising a pressure-sensitive adhesive layer formed from a solvent-based pressure-sensitive adhesive composition. In an aspect having a solvent-based pressure-sensitive adhesive layer formed from a solvent-based pressure-sensitive adhesive composition, the effect of improving the refractive index by the technology disclosed herein is preferably achieved.

(Formation of adhesive layer)
The adhesive layer disclosed here can be formed by a conventionally known method. For example, a method of forming a pressure-sensitive adhesive layer by applying a pressure-sensitive adhesive composition to a surface having releasability (release surface) and drying can be employed. In a pressure-sensitive adhesive sheet having a substrate, for example, a method (direct method) of forming a pressure-sensitive adhesive layer by directly applying (typically applying) a pressure-sensitive adhesive composition to the substrate and drying it is adopted. be able to. Alternatively, a method of applying a pressure-sensitive adhesive composition to a surface having releasability (release surface) and drying to form a pressure-sensitive adhesive layer on the surface and transferring the pressure-sensitive adhesive layer to a substrate (transfer method). may be adopted. As the release surface, for example, the surface of a release liner, which will be described later, can be preferably used. The pressure-sensitive adhesive layer disclosed herein is typically formed continuously, but is not limited to such a form. It may be a formed pressure-sensitive adhesive layer.

Application of the adhesive composition can be performed using a conventionally known coater such as a gravure roll coater, a die coater, and a bar coater. Alternatively, the adhesive composition may be applied by impregnation, curtain coating, or the like.
From the viewpoint of promoting the cross-linking reaction, improving production efficiency, etc., it is preferable to dry the pressure-sensitive adhesive composition under heating. The drying temperature can be, for example, about 40 to 150.degree. C., preferably about 60 to 130.degree. After drying the pressure-sensitive adhesive composition, it may be further aged for the purpose of adjusting migration of components in the pressure-sensitive adhesive layer, progressing the crosslinking reaction, relaxing strain that may exist in the pressure-sensitive adhesive layer, and the like.

The pressure-sensitive adhesive layer disclosed herein may have a single layer structure or a multilayer structure of two or more layers. From the viewpoint of productivity and the like, the pressure-sensitive adhesive layer preferably has a single-layer structure.

The thickness of the adhesive layer is set within a range in which the total thickness of the adhesive sheet is 100 μm or less. For example, the thickness of the adhesive layer is appropriately about 100 μm or less, preferably about 70 μm or less, more preferably about 50 μm or less. The thickness of the adhesive layer can be approximately 35 μm or less. A pressure-sensitive adhesive layer with a limited thickness can well meet demands for thinning and weight reduction. Further, according to the technology disclosed herein, it is possible to obtain a pressure-sensitive adhesive having acid resistance and alkali resistance and sufficient adhesive strength with the structure having the limited thickness as described above. The lower limit of the thickness of the pressure-sensitive adhesive layer is not particularly limited, and from the viewpoint of adhesion to the adherend, it is advantageous to set it to about 1 μm or more, suitably about 3 μm or more, and preferably about 3 μm or more. It is 10 μm or more, more preferably approximately 15 μm or more, further preferably approximately 20 μm or more, may be approximately 30 μm or more, may be approximately 35 μm or more, or may be approximately 40 μm or more. By increasing the thickness of the pressure-sensitive adhesive layer, more excellent pressure-sensitive adhesive properties are likely to be obtained. Moreover, when the thickness of the pressure-sensitive adhesive layer increases, there is a tendency that the permeation prevention property of the acidic liquid and the alkaline liquid in the thickness direction is excellent. In addition, in a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer (first pressure-sensitive adhesive layer and second pressure-sensitive adhesive layer) on each side of a substrate, the thickness of each pressure-sensitive adhesive layer may be the same or different. .

<Base material (base material layer)>
In the aspect in which the pressure-sensitive adhesive sheet disclosed herein is in the form of a double-sided pressure-sensitive adhesive sheet with a substrate, the substrate that supports (backs) the pressure-sensitive adhesive layer may be resin film, paper, cloth, rubber sheet, foam sheet, or metal. Foils, composites thereof, and the like can be used. Examples of paper include Japanese paper, kraft paper, glassine paper, woodfree paper, synthetic paper, top coat paper, and the like. Examples of fabrics include woven fabrics and non-woven fabrics obtained by spinning various fibrous materials alone or by blending them. Examples of the fibrous substance include cotton, staple fiber, manila hemp, pulp, rayon, acetate fiber, polyester fiber, polyvinyl alcohol fiber, polyamide fiber, and polyolefin fiber. Examples of rubber sheets include natural rubber sheets and butyl rubber sheets. Examples of foam sheets include foamed polyurethane sheets and foamed polychloroprene rubber sheets. Examples of metal foil include aluminum foil and copper foil.

The nonwoven fabric referred to here is a concept that refers to a nonwoven fabric for adhesive sheets that is mainly used in the field of adhesive tapes and other adhesive sheets, and is typically a nonwoven fabric that is produced using a general paper machine. (sometimes referred to as so-called "paper"). The term "resin film" as used herein is typically a non-porous resin sheet and means a (voidless) resin film that does not substantially contain air bubbles. Therefore, the resin film is a concept that is distinguished from foam films, non-woven fabrics, and woven fabrics (that is, does not include foams, non-woven fabrics, and woven fabrics). The resin film may be a non-stretched film, a uniaxially stretched film, or a biaxially stretched film.

As the base material constituting the pressure-sensitive adhesive sheet with a base material, a base film containing a resin film can be preferably used. The base film is typically an independently shape-maintainable (independent) member. The substrate in the technology disclosed herein can be substantially composed of such a base film. Alternatively, the substrate may contain an auxiliary layer in addition to the base film. Examples of the auxiliary layer include a colored layer, a reflective layer, an undercoat layer, an antistatic layer, etc. provided on the surface of the base film.

The resin film is a film containing a resin material as a main component (for example, a component contained in the resin film in an amount exceeding 50% by weight). Examples of resin films include polyolefin resin films such as polyethylene (PE), polypropylene (PP), and ethylene/propylene copolymer; polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), and the like. vinyl chloride resin film; vinyl acetate resin film; polyimide resin film; polyamide resin film; fluorine resin film; The resin film may be a rubber-based film such as a natural rubber film or a butyl rubber film. Among them, from the viewpoint of handleability and workability, a polyester film is preferred, and a PET film is particularly preferred.

The base material may be one having transparency, or one having a light shielding property or a light reducing property. In some embodiments, the substrate (eg, resin film) can contain a colorant. Thereby, the light transmittance (light shielding property) of the substrate can be adjusted. Adjusting the light transmittance (for example, normal light transmittance) of the substrate can also help adjust the light transmittance of the substrate and further the light transmittance of the pressure-sensitive adhesive sheet including the substrate.

As the colorant, conventionally known pigments and dyes can be used, like the colorant that can be contained in the pressure-sensitive adhesive layer. The coloring agent is not particularly limited, and may be, for example, black, gray, white, red, blue, yellow, green, yellow-green, orange, purple, gold, silver, pearl color, and the like.

The base material (for example, resin film) may optionally contain fillers (inorganic fillers, organic fillers, etc.), dispersants (surfactants, etc.), anti-aging agents, antioxidants, UV absorbers, Various additives such as antistatic agents, lubricants and plasticizers may be added. The blending ratio of various additives is about less than 30% by weight (for example, less than 20% by weight, typically less than 10% by weight).

The base material (for example, resin film) may have a single-layer structure, or may have a multi-layer structure of two layers, three layers, or more. From the viewpoint of shape stability, the substrate preferably has a single-layer structure. In the case of a multilayer structure, at least one layer (preferably all layers) is preferably a layer having a continuous structure of the resin (for example, polyester resin). A method for manufacturing the substrate (typically a resin film) is not particularly limited, and a conventionally known method may be appropriately adopted. For example, conventionally known general film forming methods such as extrusion molding, inflation molding, T-die casting, and calender roll molding can be employed as appropriate.

The substrate may be colored with a colored layer arranged on the surface of the base film (preferably resin film). In such a substrate having a structure including a base film and a colored layer, the base film may or may not contain a coloring agent. The colored layer may be arranged on either one surface of the base film, or may be arranged on both surfaces. In the configuration in which the colored layers are arranged on both surfaces of the base film, the configurations of the colored layers may be the same or different.

The surface of the substrate may be subjected to conventionally known surface treatments such as corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, application of a primer, and the like. Such a surface treatment can be a treatment for improving the adhesion between the substrate and the adhesive layer, in other words, the anchoring property of the adhesive layer to the substrate.

The thickness of the substrate is set within a range in which the total thickness of the adhesive sheet is 100 μm or less. In some embodiments, the thickness of the substrate may be approximately 70 μm or less, approximately 30 μm or less, or approximately 15 μm or less (for example, approximately 8 μm or less) depending on the intended use and usage mode of the pressure-sensitive adhesive sheet. . Substrates with limited thickness can be well suited to thinning and light weight requirements. In addition, a pressure-sensitive adhesive sheet having a substrate with a limited thickness tends to exhibit the action of the pressure-sensitive adhesive layer more effectively. The lower limit of the thickness of the substrate is not particularly limited. From the standpoint of handleability and workability of the pressure-sensitive adhesive sheet, the thickness of the base material is suitably about 2 μm or more, preferably about 5 μm or more, for example about 10 μm or more.

<Release liner>
In the technology disclosed herein, a release liner can be used in the formation of the adhesive layer, production of the adhesive sheet, storage of the adhesive sheet before use, distribution, shape processing, and the like. The release liner is not particularly limited. A release liner or the like made of a low-adhesion material such as polypropylene can be used. The release treatment layer may be formed by surface-treating the liner base material with a release treatment agent such as a silicone-based, long-chain alkyl-based, fluorine-based, or molybdenum sulfide release agent.

<Application>
The pressure-sensitive adhesive sheet disclosed herein can be used for various applications that require acid-resistant or alkali-resistant bonding and fixing, and is suitable as a structural material, for example. A pressure-sensitive adhesive sheet used as a structural material is generally not supposed to be peeled off from an adherend, and is semi-permanently retained on the adherend. The pressure-sensitive adhesive sheet disclosed herein has a thickness of 100 μm or less, and can achieve highly reliable bonding and fixing, and is therefore suitable for use in portable electronic devices where there is a strong demand for miniaturization and thinning. Further, various members such as metal members that constitute the portable electronic device may be subjected to processing such as formation of openings for various sensors such as a fingerprint sensor and camera lenses. Such processing steps can include steps using acidic liquids or alkaline liquids, such as immersion in acidic etching liquids and cleaning with alkaline cleaning liquids. By bonding and fixing with excellent adhesion, it is possible to process the member with the adhesive sheet attached. The pressure-sensitive adhesive sheet is particularly suitable for fixing members for portable electronic devices to which such processing is applied.

Non-limiting examples of the above portable electronic devices include mobile phones, smartphones, tablet computers, notebook computers, various wearable devices (for example, wrist wear type worn on the wrist like a wristwatch, Eyewear type including glasses type (monocular type and binocular type, including head-mounted type), clothes type attached to shirts, socks, hats, etc. in the form of accessories, earphones ear-wear type, etc.), digital cameras, digital video cameras, audio equipment (portable music players, IC recorders, etc.), calculators (calculators, etc.), portable game devices, electronic dictionaries, electronic notebooks, electronic books, vehicle-mounted information equipment, portable radios, portable televisions, portable printers, portable scanners, portable modems, etc. In this specification, the term “portable” means not only being able to be simply carried, but also having a level of portability that allows an individual (a typical adult) to carry it relatively easily. shall mean.

The pressure-sensitive adhesive sheet disclosed herein can be used, for example, for the purpose of fixing a pressure-sensitive sensor and other members in a portable electronic device including a pressure-sensitive sensor among such portable electronic devices. In some aspects, the adhesive sheet is a device for indicating a position on the screen (typically a pen-type or mouse-type device) and a device for detecting the position, and a plate corresponding to the screen ( It is used to fix a pressure sensor and other members in an electronic device (typically a portable electronic device) equipped with a function that allows the absolute position to be specified on a touch panel (typically a touch panel). can be

In addition, the adhesive sheet disclosed herein is suitable for use placed on the back surface of a display screen (display section) such as a touch panel display in portable electronic devices. For example, some electronic devices such as portable electronic devices include light-emitting elements for the purpose of image display. ) can be sought. A pressure-sensitive adhesive sheet having a predetermined light-shielding property can be used for such electronic devices. For example, the pressure-sensitive adhesive sheet can be used for electronic devices including various light sources such as LEDs (light emitting diodes) and light emitting elements such as self-luminous organic ELs. The electronic device may be an electronic device (typically a portable electronic device) including an organic EL display device or a liquid crystal display device. For example, the adhesive sheet disclosed herein is suitable for use placed on the back surface of a display screen (display section) such as a touch panel display in portable electronic devices.

In addition, the adhesive sheet disclosed herein is suitable for portable electronic devices incorporating various sensors such as fingerprint sensors and cameras. Since the adhesive sheet disclosed herein can be processed (opening process) on an adherend such as a metal member while being attached to the adherend, it can be used for sensors and cameras constituting portable electronic devices. It is suitable for joining and fixing members that form an opening for a lens. Examples of the sensor (optical sensor) include an acceleration sensor, a proximity sensor, a brightness sensor (environmental light sensor), and the like. Such a sensor has light receiving elements for rays such as ultraviolet rays, visible rays, and infrared rays, and may have light emitting elements for specific rays such as infrared rays.

The material (adherend material) to which the pressure-sensitive adhesive sheet disclosed herein is attached is not particularly limited, but examples include copper, silver, gold, iron, tin, palladium, aluminum, nickel, titanium, Chromium, zinc, etc., or metal materials such as alloys containing two or more of these, for example, polyimide resin, acrylic resin, polyethernitrile resin, polyethersulfone resin, polyester resin (PET resin, PEN resins, etc.), polyvinyl chloride resins, polyphenylene sulfide resins, polyetheretherketone resins, polyamide resins (so-called aramid resins, etc.), polyarylate resins, polycarbonate resins, liquid crystal polymers, etc. plastic materials), inorganic materials such as alumina, zirconia, soda glass, quartz glass, and carbon. Among them, metal materials such as copper, aluminum, and stainless steel, polyester resins such as PET, and resin materials (typically plastic materials) such as polyimide resins, aramid resins, and polyphenylene sulfide resins are widely used. ing. The adhesive sheet disclosed herein can be used by being attached to a member made of the above materials. In the double-sided pressure-sensitive adhesive sheet (specifically, double-sided pressure-sensitive adhesive sheet) disclosed herein, each pressure-sensitive adhesive surface (first pressure-sensitive adhesive surface and second pressure-sensitive adhesive surface) adheres well to adherends made of different materials. It can be preferably used for bonding two or more different materials among the various adherend materials described above.

The above materials may be materials for members constituting products such as electronic devices. Further, the above material may be a material that constitutes a fixed object (for example, an electromagnetic wave shield, a back member such as a reinforcing plate, etc.) such as the pressure-sensitive sensor or the display section. The object to be fixed means an object to which the pressure-sensitive adhesive sheet is attached, that is, an adherend. Further, the back surface member refers to a member arranged on the opposite side of the front surface (viewing side) of the pressure-sensitive sensor and the display unit in, for example, a portable electronic device. It may be a member or the like that constitutes the support portion 240 arranged on the back surface of the 200 . The object to be fixed may have either a single-layer structure or a multi-layer structure, and the surface to which the pressure-sensitive adhesive sheet is attached (attachment surface) may be subjected to various surface treatments. Although not particularly limited, an example of a fixed object is a back member having a thickness of 1 μm or more (typically 5 μm or more, for example 60 μm or more, further 120 μm or more) and about 1500 μm or less (for example, 800 μm or less). mentioned.

In addition, the adhesive sheet disclosed herein is suitable for application to be attached to a member having a surface (adhesive sheet attaching surface) formed of a metal material, for example. Examples of such an adherend include members having on the surface various metal materials (e.g., aluminum, stainless steel, etc.) exemplified as the adherend material, and preferred examples include stainless steel members and aluminum members. and other metal members. The above-mentioned metal member, in the form of a laminate to which an adhesive sheet is attached, may be exposed to acidic liquids and alkaline liquids for opening processing and the like. It is preferable to use an adhesive sheet having alkali resistance. According to the laminate, even when the adhesive sheet is exposed to an acidic liquid and an alkaline liquid for processing the metal member, the pressure-sensitive adhesive sheet can maintain a good adhesion state to the metal member. The metal member may be, for example, a member constituting a supporting portion 240 of a display device 200 shown in FIG. 4, which will be described later. Moreover, the pressure-sensitive adhesive sheet used for the above applications may have holes formed in advance by punching or the like at portions corresponding to the processed portions (opening forming portions, etc.) of the metal member.

In addition, the member or material to which the pressure-sensitive adhesive sheet is attached (at least one adherend in the case of the double-sided pressure-sensitive adhesive sheet) may have optical transparency. The light transmittance of the adherend may be, for example, greater than 50% and equal to or greater than 70%. In some preferred embodiments, the adherend has a light transmittance of 80% or higher, more preferably 90% or higher, and may be 95% or higher (eg, 95-100%). Such a material may be a resin film (for example, a polyester-based resin film such as a PET film) arranged on the back surface of the image display portion of various devices such as portable electronic devices. The pressure-sensitive adhesive sheet disclosed herein can be preferably used in a mode of being attached to an adherend (for example, a member) having a light transmittance equal to or higher than a predetermined value as described above. The light transmittance is measured using a commercially available transmittance meter in accordance with JIS K 7136:2000.

As described above, according to the technology disclosed herein, a laminate including an adhesive sheet and a member to which the adhesive sheet is attached is provided. In some embodiments, the laminate including the adhesive sheet is a laminate including the adhesive sheet and a metal member (first member). In some aspects, the adherend material having the above-described light transmittance is attached to the side of the pressure-sensitive adhesive sheet opposite to the surface to which the metal member is attached. In this aspect, the laminate including the adhesive sheet is a laminate including the adhesive sheet and a member (second member) having optical transparency. In some preferred embodiments, the laminate is a laminate that includes a metal member (first member), an adhesive sheet, and a member having optical transparency (second member) in this order. In addition, the said adhesive sheet is also called an adhesive layer in a laminated body.

Moreover, in some aspects, the laminate including the adhesive sheet is a laminate including the adhesive sheet and a member (second member) having optical transparency. In this aspect, one adhesive surface of the adhesive sheet is adhered to the member having the optical transparency. Such a laminate is also called an adhesive sheet with a light-transmitting member. Also, the other adhesive surface of the adhesive sheet may be attached to the metal member.

FIG. 3 shows a structural example of the laminate. A laminate 50 shown in FIG. 3 includes a first member 41, a substrate-less pressure-sensitive adhesive sheet 1, and a second member 42 in this order. Specifically, in the laminate 50, one adhesive surface (first adhesive surface) 1A of the substrate-less adhesive sheet 1 is adhered to the first member 41, and the other adhesive surface of the adhesive sheet 1 ( A second adhesive surface 1B is adhered to the second member 42 . In this embodiment, both the first member 41 and the second member 42 have a sheet-like or plate-like shape, and the laminate 50 has a multilayer structure. The details of the members constituting the laminate are as described above for the members, materials, and adherends, so redundant description will not be repeated.

In some preferred embodiments, the first member 41 is a metal member, and the metal materials and metal members exemplified above as the adherend material are used. Such a metal member may be, for example, a member constituting a supporting portion 240 of a display device 200 shown in FIG. 4, which will be described later. Moreover, in some preferred embodiments, the second member 42 is a light-transmitting member and has the light transmittance of the light-transmitting adherend described above. The second member 42 is preferably a member made of a resin film, more preferably a polyester-based resin film (more specifically, a PET-based resin film). The second member 42 may be, for example, a member arranged on the back side of the display section in the display device. The laminate 50 as described above can typically be a component of an organic EL display device, a liquid crystal display device, or the like. The laminated body 50 is suitable for use, for example, to be arranged on the back surface of an image display section (which may be a display section such as a touch panel display) of various devices such as portable electronic devices.

The pressure-sensitive adhesive sheet disclosed herein is preferably used in electronic devices including various light sources such as LEDs and light-emitting elements such as self-luminous organic ELs. For example, it can be preferably used for electronic equipment (typically portable electronic equipment) equipped with an organic EL display device or a liquid crystal display device that requires predetermined optical properties.

FIG. 4 is an exploded perspective view schematically showing a configuration example of the display device. As shown in FIG. 4 , the display device 200 included in the mobile electronic device 100 includes a display section 220 including a cover member, an organic EL unit, and the like, and a support section 240 . Display device 200 further includes an adhesive sheet 230 . In this configuration example, the adhesive sheet 230 is in the form of a double-sided adhesive sheet (double-sided adhesive sheet) that fixes the members forming the display section 220 and the support section 240 . Note that the support portion 240 includes a substrate (a metal plate such as a stainless steel plate or an aluminum plate) and the like. The pressure-sensitive adhesive sheet disclosed herein is preferably used as a component of the display device as described above.

Matters disclosed by this specification include the following.
[1] A display device including a display portion including a cover member and an organic EL unit, and a support portion,
A double-sided adhesive adhesive sheet is attached to the support,
The adhesive sheet has a thickness of 100 μm or less,
The pressure-sensitive adhesive sheet has an acrylic pressure-sensitive adhesive layer containing an acrylic polymer,
The pressure-sensitive adhesive sheet has a 180-degree peel strength F0 against a stainless steel plate measured at a tensile speed of 300 mm/min of 3.0 N/5 mm or more, and an adhesive strength retention rate after immersion in an acidic solution and an adhesive strength retention rate after immersion in an alkaline solution. are both 80% or more.
[2] The display device according to [1] above, wherein the pressure-sensitive adhesive sheet is a substrate-less double-sided adhesive pressure-sensitive adhesive sheet comprising the pressure-sensitive adhesive layer.
[3] The display device according to [1] above, wherein the pressure-sensitive adhesive sheet further comprises a base layer, and is a double-sided adhesive pressure-sensitive adhesive sheet with a base having the pressure-sensitive adhesive layer on each side of the base layer.
[4] The acrylic polymer is a polymer of a monomer component containing 60% by weight or more of an alkyl (meth)acrylate having an alkyl group having 5 or more carbon atoms at the ester end of the above [1] to [3]. The display device according to any one of
[5] The display device according to any one of [1] to [4] above, wherein the monomer component constituting the acrylic polymer includes a monomer having a nitrogen atom-containing ring and a carboxy group-containing monomer.
[6] The display device according to [5] above, wherein the total proportion of the nitrogen atom-containing ring-containing monomer and the carboxy group-containing monomer in the monomer component is 6.5% by weight or more and 40% by weight or less.
[7] The ratio (A _N /A _C ) of the content (A _N ) of the monomer having a nitrogen atom-containing ring to the content (A _C ) of the carboxy group-containing monomer is in the range of 1 to 40. The display device according to [5] or [6] above.
[8] The display device according to any one of [1] to [7] above, wherein the monomer component constituting the acrylic polymer contains a hydroxyl group-containing monomer in a proportion of 10% by weight or less.

[11] A double-sided adhesive pressure-sensitive adhesive sheet having a thickness of 100 µm or less,
It has an acrylic pressure-sensitive adhesive layer containing an acrylic polymer,
The 180 degree peel strength F0 against a stainless steel plate measured at a tensile speed of 300 mm / min is 3.0 N / 5 mm or more,
A pressure-sensitive adhesive sheet having an adhesive strength retention rate after immersion in an acidic solution and an adhesive strength retention rate after immersion in an alkaline solution of 80% or more.
[12] The pressure-sensitive adhesive sheet according to [11] above, which is a substrate-less double-sided adhesive pressure-sensitive adhesive sheet comprising the pressure-sensitive adhesive layer.
[13] The pressure-sensitive adhesive sheet according to [11] above, which is a double-sided adhesive pressure-sensitive adhesive sheet with a substrate, further comprising a substrate layer and having the pressure-sensitive adhesive layer on each surface of the substrate layer.
[14] The above [11] to [13], wherein the acrylic polymer is a monomer component polymer containing 60% by weight or more of an alkyl (meth)acrylate having an alkyl group having 5 or more carbon atoms at the ester end. The pressure-sensitive adhesive sheet according to any one of 1.
[15] The pressure-sensitive adhesive sheet according to any one of [11] to [14] above, wherein the monomer component constituting the acrylic polymer includes a monomer having a nitrogen atom-containing ring and a carboxy group-containing monomer.
[16] The pressure-sensitive adhesive sheet of [15] above, wherein the total proportion of the nitrogen atom-containing ring-containing monomer and the carboxy group-containing monomer in the monomer component is 6.5% by weight or more and 40% by weight or less.
[17] The ratio (A _N /A _C ) of the content (A _N ) of the monomer having a nitrogen atom-containing ring to the content (A _C ) of the carboxy group-containing monomer is in the range of 1 to 40. The pressure-sensitive adhesive sheet according to [15] or [16] above.
[18] The pressure-sensitive adhesive sheet according to any one of [11] to [17] above, wherein the monomer component constituting the acrylic polymer contains a hydroxyl group-containing monomer in a proportion of 10% by weight or less.
[19] The pressure-sensitive adhesive sheet according to any one of [11] to [18] above, which is used for fixing a member of a portable electronic device.

[21] A laminate comprising a metal member (first member) and an adhesive sheet attached to the surface of the metal member,
The pressure-sensitive adhesive sheet is a double-sided adhesive pressure-sensitive adhesive sheet having a thickness of 100 μm or less,
The pressure-sensitive adhesive sheet has an acrylic pressure-sensitive adhesive layer containing an acrylic polymer,
The pressure-sensitive adhesive sheet has a 180 degree peel strength F0 against a stainless steel plate measured at a tensile speed of 300 mm/min of 3.0 N/5 mm or more, and an adhesive strength retention rate after immersion in an acidic solution and an adhesive strength retention after immersion in an alkaline solution. A laminate having both ratios of 80% or more.
[22] A laminate (also referred to as a pressure-sensitive adhesive sheet with a light-transmitting member) comprising a light-transmitting member (second member) and a double-sided adhesive pressure-sensitive adhesive sheet,
The pressure-sensitive adhesive sheet is a double-sided adhesive pressure-sensitive adhesive sheet having a thickness of 100 μm or less,
The pressure-sensitive adhesive sheet has an acrylic pressure-sensitive adhesive layer containing an acrylic polymer,
The pressure-sensitive adhesive sheet has a 180 degree peel strength F0 against a stainless steel plate measured at a tensile speed of 300 mm/min of 3.0 N/5 mm or more, and an adhesive strength retention rate after immersion in an acidic solution and an adhesive strength retention after immersion in an alkaline solution. A laminate having both ratios of 80% or more.
[23] A laminate comprising a metal member (first member), an adhesive sheet, and a light-transmitting member (second member) in this order,
The pressure-sensitive adhesive sheet is a double-sided adhesive pressure-sensitive adhesive sheet having a thickness of 100 μm or less,
The pressure-sensitive adhesive sheet has an acrylic pressure-sensitive adhesive layer containing an acrylic polymer,
The pressure-sensitive adhesive sheet has a 180 degree peel strength F0 against a stainless steel plate measured at a tensile speed of 300 mm/min of 3.0 N/5 mm or more, and an adhesive strength retention rate after immersion in an acidic solution and an adhesive strength retention after immersion in an alkaline solution. A laminate having both ratios of 80% or more.
[24] The laminate according to any one of [21] to [23] above, wherein the metal member is an aluminum member or a stainless steel member.
[25] The laminate according to [22] or [23] above, wherein the light transmittance of the member having light transmittance is greater than 50%.
[26] The laminate according to [22], [23] or [25] above, wherein the light-transmitting member comprises a resin film.
[27] The above [21] to [26], wherein the acrylic polymer is a monomer component polymer containing 60% by weight or more of an alkyl (meth)acrylate having an alkyl group having 5 or more carbon atoms at the ester end. The laminate according to any one of .
[28] The laminate according to any one of [21] to [27] above, wherein the monomer component constituting the acrylic polymer includes a monomer having a nitrogen atom-containing ring and a carboxy group-containing monomer.
[29] The laminate according to [28] above, wherein the total proportion of the nitrogen atom-containing ring-containing monomer and the carboxy group-containing monomer in the monomer component is 6.5% by weight or more and 40% by weight or less.
[30] The ratio (A _N /A _C ) of the content (A _N ) of the monomer having a nitrogen atom-containing ring to the content (A _C ) of the carboxy group-containing monomer is in the range of 1 to 40. The laminate according to [28] or [29] above.
[31] The laminate according to any one of [21] to [30] above, wherein the monomer component constituting the acrylic polymer contains a hydroxyl group-containing monomer in a proportion of 10% by weight or less.
[32] The laminate according to any one of [21] to [31] above, wherein the pressure-sensitive adhesive sheet is a substrate-less double-sided adhesive pressure-sensitive adhesive sheet comprising the pressure-sensitive adhesive layer.
[33] Any one of [21] to [31] above, wherein the pressure-sensitive adhesive sheet further comprises a substrate layer, and is a double-sided adhesive pressure-sensitive adhesive sheet with a substrate having the pressure-sensitive adhesive layer on each surface of the substrate layer. The laminate according to any one of the above.
[34] The laminate according to any one of [21] to [33] above, which is used for portable electronic devices.

Several examples relating to the present invention are described below, but the present invention is not intended to be limited to those shown in such examples. "Parts" in the following description are by weight unless otherwise specified.

<Evaluation method>
[Normal adhesive strength F0]
Under an environment of 23° C. and 50% RH, a PET film having a thickness of 50 μm is adhered to one adhesive surface of the double-sided adhesive sheet for lining, and the sheet is cut into a size of 5 mm in width and 50 mm in length to prepare a measurement sample. . Under the same environment, the adhesive surface (surface to be measured) of the prepared measurement sample is pressure-bonded to the surface of a stainless steel plate (SUS304BA plate, size 10 cm×10 cm) by reciprocating a 2 kg roller once. This is left in a constant temperature bath at 50° C. for 30 minutes. Then, in an environment of 23 ° C. and 50% RH, using a tensile tester, according to JIS Z 0237: 2000, the peel strength (normal state adhesive The force F0) [N/5mm] is measured. As the tensile tester, for example, a device name "Tensilon" manufactured by Shimadzu Corporation or an equivalent thereof is used.

[Adhesive strength F1 after immersion in acid solution]
A measurement sample (adhesive sheet) with a width of 5 mm and a length of 50 mm lined with a PET film was prepared in the same manner as the measurement of the normal state adhesive strength F0, and the adhesive surface (surface to be measured) of the measurement sample was attached to a stainless steel plate (size 10 cm). × 10 cm). The stainless steel plate is placed horizontally so that it faces downward, and an iron chloride aqueous solution (5% FeCl ₂ aqueous solution) is applied to the entire end surface (four sides) of the measurement sample attached to the stainless steel plate so that the end surface of the measurement sample is exposed. The end face of the measurement sample is immersed in the iron chloride aqueous solution. After covering the whole measurement sample on the stainless steel plate with a PET film so that the moisture does not volatilize, it is left in a constant temperature bath at 50° C. for 30 minutes. After that, the measurement sample attached to the stainless steel plate is taken out from the constant temperature bath, the PET film is removed, the iron chloride aqueous solution is washed away with tap water, and the water adhering to the measurement sample and the stainless steel plate is wiped off with a waste cloth. Then, using a tensile tester, the post-immersion adhesive strength F1 [N/5 mm] in the acid solution is measured under the same conditions as the measurement of the normal adhesive strength F0. The time from immersion in the iron chloride aqueous solution for 30 minutes to measurement of adhesive strength shall be within 10 minutes.

[Adhesive strength F2 after immersion in alkaline solution]
A measurement sample (adhesive sheet) with a width of 5 mm and a length of 50 mm lined with a PET film was prepared in the same manner as the measurement of the normal state adhesive strength F0, and the adhesive surface (surface to be measured) of the measurement sample was attached to a stainless steel plate (size 10 cm). × 10 cm). A sodium hydroxide aqueous solution (50% NaOH aqueous solution) is applied to the entire end surface (four sides) of the measurement sample attached to the stainless steel plate so that the stainless steel plate faces downward, and the end surface of the measurement sample is exposed. The end face of the measurement sample is immersed in the sodium hydroxide aqueous solution. After covering the whole measurement sample on the stainless steel plate with a PET film so that the moisture does not volatilize, it is left in a constant temperature bath at 50° C. for 30 minutes. After that, the measurement sample attached to the stainless steel plate is taken out from the constant temperature bath, the PET film is removed, the aqueous sodium hydroxide solution is washed away with tap water, and water adhering to the measurement sample and the stainless steel plate is wiped off with a waste cloth. Then, using a tensile tester, the adhesive strength F2 [N/5 mm] after being immersed in an alkaline solution is measured under the same conditions as the measurement of the normal adhesive strength F0. The time from the immersion in the sodium hydroxide aqueous solution for 30 minutes to the measurement of the adhesive force shall be within 10 minutes.

[Adhesive strength retention rate]
The adhesive strength retention rate after immersion in the acidic solution and the adhesive strength maintenance rate after immersion in the alkaline solution of the adhesive sheet according to each example are respectively compared to the normal state adhesive strength F0 [N / 5 mm] and the adhesive strength after immersion in the acidic solution F1 [N / 5 mm]. and the ratio [%] of the adhesive strength F2 [N/5 mm] after immersion in an alkaline solution to the normal adhesive strength F0 [N/5 mm].

[Evaluation of edge floating after immersion in acidic solution and after immersion in alkaline solution]
In the measurement of the adhesive strength F1 after immersion in the acid solution, after immersion in the iron chloride aqueous solution, it was washed with tap water and the adhering moisture was wiped off with a waste cloth. (Evaluation of edge floating after immersion in acidic solution).
In addition, in the measurement of the adhesive strength F2 after immersion in the alkaline solution, after immersion in an aqueous sodium hydroxide solution, it was washed with tap water and the attached water was wiped off with a waste cloth. Visually confirm (evaluation of edge floating after immersion in alkaline solution).
After immersion in the acidic solution and after immersion in the alkaline solution, if no edge lift is observed, it is judged as "O" (pass), and if edge lift is observed, it is judged as "X".

<Example 1>
(Preparation of acrylic polymer)
75 parts of 2-ethylhexyl acrylate (2EHA) as a monomer component, 3 parts of acrylic acid (AA) and 2-hydroxyethyl acrylate were placed in a reaction vessel equipped with a stirrer, thermometer, nitrogen gas inlet tube, reflux condenser and dropping funnel. 0.1 part of (HEA), 25 parts of acryloylmorpholine (ACMO), and ethyl acetate as a polymerization solvent were charged and stirred for 2 hours while introducing nitrogen gas. After removing oxygen in the polymerization system in this way, 0.2 parts of 2,2′-azobisisobutyronitrile (AIBN) is added as a polymerization initiator, and the solution is polymerized at 60° C. for 8 hours to obtain acrylic resin. A solution of the system polymer (A1) was obtained. Mw of this acrylic polymer (A1) was about 110×10 ⁴ .

(Preparation of adhesive composition)
In the acrylic polymer (A1) solution, an epoxy-based cross-linking agent (trade name “TETRAD-C”, manufactured by Mitsubishi Gas Chemical Co., Ltd., 1 ,3-bis(N,N-diglycidylaminomethyl)cyclohexane) 0.03 part was added and mixed with stirring to prepare an adhesive composition.

(Preparation of adhesive sheet)
The adhesive composition was applied to the release surface of a 38 μm thick polyester release liner (trade name “Diafoil MRF”, manufactured by Mitsubishi Polyester Co., Ltd.) and dried at 100° C. for 2 minutes to form a 35 μm thick adhesive. formed a layer. The release surface of a 25 μm-thick polyester release liner (trade name “Diafoil MRF”, manufactured by Mitsubishi Polyester Co., Ltd.) was attached to the pressure-sensitive adhesive layer. Thus, a substrate-less double-sided PSA sheet having a thickness of 35 μm and having both sides protected by the two polyester release liners was obtained.

<Example 2>
To the solution of the acrylic polymer (A1) prepared in Example 1, 100 parts of the acrylic polymer (A1) contained in the solution was added with a tackifying resin (B1) (product name "Haritac SE10", manufactured by Harima Kasei Co., Ltd. Hydrogenated rosin glycerin ester, softening point 75 to 85 ° C.) 30 parts, and an isocyanate cross-linking agent as a cross-linking agent (trade name "Coronate L", manufactured by Tosoh Corporation, 75 parts of trimethylolpropane / tolylene diisocyanate trimer adduct. % ethyl acetate solution) and 0.04 parts of an epoxy-based cross-linking agent (trade name “TETRAD-C”, manufactured by Mitsubishi Gas Chemical Co., Ltd., 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane) were added and mixed with stirring to prepare a pressure-sensitive adhesive composition. A substrate-less double-sided pressure-sensitive adhesive sheet according to this example was produced in the same manner as in Example 1, except that the obtained pressure-sensitive adhesive composition was used.

<Example 3>
To the acrylic polymer (A1) solution prepared in Example 1, 30 parts of the tackifying resin (B1) and the isocyanate cross-linking agent as a cross-linking agent are added to 100 parts of the acrylic polymer (A1) contained in the solution. 2 parts and 0.05 parts of the above epoxy-based cross-linking agent are added, and carbon black particles (manufactured by Toyocolor Co., Ltd., trade name "Multilac A903", average particle size 400 nm) are added to the pressure-sensitive adhesive layer at 6.58%. were added and stirred and mixed to prepare a pressure-sensitive adhesive composition. A substrate-less double-sided pressure-sensitive adhesive sheet according to this example was produced in the same manner as in Example 1, except that the obtained pressure-sensitive adhesive composition was used.

<Example 4>
To the acrylic polymer (A1) solution prepared in Example 1, 10 parts of the tackifying resin (B1) and the tackifying resin (B2) (product name "Haritac PCJ", manufactured by Harima Kasei Co., Ltd., polymerized rosin ester, softening point: about 118 to 128 ° C.) 15 parts, 2 parts of the above isocyanate cross-linking agent as a cross-linking agent and 0.07 part of the above epoxy cross-linking agent are added, A pressure-sensitive adhesive composition was prepared by stirring and mixing. A substrate-less double-sided pressure-sensitive adhesive sheet according to this example was produced in the same manner as in Example 1, except that the obtained pressure-sensitive adhesive composition was used.

<Example 5>
A solution of acrylic polymer (A2) was obtained in the same manner as for acrylic polymer (A1), except that the monomer components were changed to 80 parts of 2EHA, 3 parts of AA, 0.1 part of HEA and 20 parts of ACMO. A pressure-sensitive adhesive composition according to this example was prepared in the same manner as in Example 2 except that the obtained acrylic polymer (A2) solution was used, and this pressure-sensitive adhesive composition was used in the same manner as in Example 1. A substrate-less double-sided pressure-sensitive adhesive sheet according to was produced.

<Example 6>
A solution of an acrylic polymer (A3) was obtained in the same manner as the acrylic polymer (A1) except that the monomer components were changed to 65 parts of 2EHA, 3 parts of AA, 0.1 part of HEA and 35 parts of ACMO. A pressure-sensitive adhesive composition according to this example was prepared in the same manner as in Example 2 except that the obtained acrylic polymer (A3) solution was used, and this pressure-sensitive adhesive composition was used in the same manner as in Example 1. A substrate-less double-sided pressure-sensitive adhesive sheet according to was produced.

<Example 7>
A solution of acrylic polymer (A4) was obtained in the same manner as acrylic polymer (A1) except that the monomer components were changed to 90 parts of 2EHA, 3 parts of AA, 0.1 part of HEA and 10 parts of ACMO. A pressure-sensitive adhesive composition according to this example was prepared in the same manner as in Example 2 except that the obtained acrylic polymer (A4) solution was used, and this pressure-sensitive adhesive composition was used in the same manner as in Example 1. A substrate-less double-sided pressure-sensitive adhesive sheet according to was produced.

<Example 8>
Acrylic polymer (A5) was prepared in the same manner as acrylic polymer (A1) except that the monomer components were changed to 75 parts of 2EHA, 3 parts of AA, 0.1 part of HEA and 25 parts of N-vinyl-2-pyrrolidone (NVP). A solution of A pressure-sensitive adhesive composition according to this example was prepared in the same manner as in Example 2 except that the obtained acrylic polymer (A5) solution was used, and this pressure-sensitive adhesive composition was used in the same manner as in Example 1. A substrate-less double-sided pressure-sensitive adhesive sheet according to was produced.

<Example 9>
A solution of acrylic polymer (A6) was obtained in the same manner as the preparation of acrylic polymer (A1) except that the monomer components were changed to 95 parts of 2EHA and 5 parts of AA. To the resulting acrylic polymer (A6) solution, 100 parts of the acrylic polymer (A6) contained in the solution, a tackifier resin (B3) (trade name "YS Polystar T-115", manufactured by Yasuhara Chemical Co., Ltd., 20 parts of a terpene phenol resin (softening point of about 115° C.) and 0.03 parts of the above epoxy-based crosslinking agent as a crosslinking agent were added and mixed with stirring to prepare a pressure-sensitive adhesive composition. A substrate-less double-sided pressure-sensitive adhesive sheet according to this example was produced in the same manner as in Example 1, except that the obtained pressure-sensitive adhesive composition was used.

<Example 10>
A solution of an acrylic polymer (A7) was obtained in the same manner as the acrylic polymer (A1) except that the monomer components were changed to 63 parts of 2EHA, 13 parts of HEA, 15 parts of NVP and 9 parts of methyl methacrylate (MMA). To the obtained acrylic polymer (A7) solution, 20 parts of the tackifying resin (B1) and 1 part of the isocyanate crosslinking agent as a crosslinking agent are added to 100 parts of the acrylic polymer (A7) contained in the solution. were added and mixed with stirring to prepare a pressure-sensitive adhesive composition. A substrate-less double-sided pressure-sensitive adhesive sheet according to this example was produced in the same manner as in Example 1, except that the obtained pressure-sensitive adhesive composition was used.

<Example 11>
A solution of the acrylic polymer (A8) was prepared in the same manner as the acrylic polymer (A1) except that the monomer components were changed to 75 parts of n-butyl acrylate (BA), 3 parts of AA, 0.1 part of HEA and 25 parts of ACMO. Obtained. A pressure-sensitive adhesive composition according to this example was prepared in the same manner as in Example 2 except that the obtained acrylic polymer (A8) solution was used, and this pressure-sensitive adhesive composition was used in the same manner as in Example 1. A substrate-less double-sided pressure-sensitive adhesive sheet according to was produced.

<Example 12>
A solution of an acrylic polymer (A9) was obtained in the same manner as the acrylic polymer (A1) except that the monomer components were changed to 95 parts of BA and 5 parts of AA. To the obtained acrylic polymer (A9) solution, 20 parts of the tackifier resin (B3) and 3 parts of the isocyanate cross-linking agent as a cross-linking agent are added to 100 parts of the acrylic polymer (A9) contained in the solution. and 0.01 part of the above epoxy-based cross-linking agent were added and mixed with stirring to prepare a pressure-sensitive adhesive composition. A substrate-less double-sided pressure-sensitive adhesive sheet according to this example was produced in the same manner as in Example 1, except that the obtained pressure-sensitive adhesive composition was used.

Table 1 shows the evaluation results of the pressure-sensitive adhesive sheets according to each example.

As shown in Table 1, in the double-sided PSA sheets according to Examples 1 to 12 having a thickness of 100 μm or less, the normal state adhesive strength F0 was 3.0 N/5 mm or more, and the adhesive strength retention rate after immersion in an acidic solution and the alkaline In Examples 1 to 8, in which the adhesive strength retention rate after immersion in the solution was 80% or more, no lifting of the edge was observed after immersion in the acidic solution or after immersion in the alkaline solution. On the other hand, in Examples 9 to 12 in which the normal state adhesive strength F0 was less than 3.0 N / 5 mm, or either the adhesive strength retention rate after immersion in an acidic solution or the adhesive strength retention rate after immersion in an alkaline solution was less than 80%. , After immersion in an acidic solution, and after immersion in an alkaline solution, edge lifting was observed.

Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

1 Adhesive Sheet 1A First Adhesive Surface 1B Second Adhesive Surface 10 Base Material (Base Material Layer)
21 adhesive layer (first adhesive layer)
21A adhesive surface, first adhesive surface 21B adhesive surface, second adhesive surface 22 adhesive layer (second adhesive layer)
31, 32 release liner 41 first member 42 second member 50 laminate 100 portable electronic device 200 display device 220 display section 240 support section

Claims (6)

A double-sided adhesive pressure-sensitive adhesive sheet having a thickness of 100 μm or less,
It has an acrylic pressure-sensitive adhesive layer containing an acrylic polymer,
The 180 degree peel strength F0 against a stainless steel plate measured at a tensile speed of 300 mm / min is 3.0 N / 5 mm or more,
Both the adhesive strength retention rate after immersion in an acidic solution and the adhesive strength retention rate after immersion in an alkaline solution are 80% or more,
The adhesive strength retention rate after immersion in the acidic solution [%] is obtained from the ratio (F1/F0 × 100) of the adhesive strength after immersion in the acidic solution F1 [N/5 mm] to the peel strength F0 [N/5 mm]. The adhesive strength retention rate after immersion in alkaline solution [%] is obtained from the ratio (F2 / F0 × 100) of the adhesive strength after immersion in alkaline solution F2 [N / 5 mm] to the peel strength F0 [N / 5 mm].
The adhesive strength F1 after immersion in the acidic solution was obtained by immersing a 5 mm wide adhesive sheet attached to a stainless steel plate as an adherend in an aqueous iron chloride solution (5% FeCl ₂ aqueous solution) for 30 minutes in an environment of 50 ° C. After that, it is the peel strength measured under the conditions of a tensile speed of 300 mm / min and a peel angle of 180 degrees,
The adhesive strength F2 after immersion in the alkaline solution was obtained by immersing a 5 mm wide adhesive sheet attached to a stainless steel plate as an adherend in an aqueous sodium hydroxide solution (50% NaOH aqueous solution) for 30 minutes in an environment of 50 ° C. After that, the pressure-sensitive adhesive sheet, which is the peel strength measured under the conditions of a tensile speed of 300 mm/min and a peel angle of 180 degrees. The pressure-sensitive adhesive sheet according to claim 1, which is a substrate-less double-sided adhesive pressure-sensitive adhesive sheet comprising the pressure-sensitive adhesive layer. 2. The pressure-sensitive adhesive sheet according to claim 1, which is a double-sided adhesive pressure-sensitive adhesive sheet with a substrate, further comprising a substrate layer and having the pressure-sensitive adhesive layer on each side of the substrate layer. The pressure-sensitive adhesive sheet according to any one of claims 1 to 3, which is used for fixing members of portable electronic devices. A display device including a display portion including a cover member and an organic EL unit, and a support portion,
A double-sided adhesive sheet having a thickness of 100 μm or less is attached to the support portion,
The pressure-sensitive adhesive sheet has an acrylic pressure-sensitive adhesive layer containing an acrylic polymer,
The pressure-sensitive adhesive sheet has a 180-degree peel strength F0 of 3.0 N/5 mm or more against a stainless steel plate measured at a tensile speed of 300 mm/min,
The pressure-sensitive adhesive sheet has both an adhesive strength retention rate after immersion in an acidic solution and an adhesive strength retention rate after immersion in an alkaline solution of 80% or more,
The adhesive strength retention rate after immersion in the acidic solution [%] is obtained from the ratio (F1/F0 × 100) of the adhesive strength after immersion in the acidic solution F1 [N/5 mm] to the peel strength F0 [N/5 mm]. The adhesive strength retention rate after immersion in alkaline solution [%] is obtained from the ratio (F2 / F0 × 100) of the adhesive strength after immersion in alkaline solution F2 [N / 5 mm] to the peel strength F0 [N / 5 mm].
The adhesive strength F1 after immersion in the acidic solution was obtained by immersing a 5 mm wide adhesive sheet attached to a stainless steel plate as an adherend in an aqueous iron chloride solution (5% FeCl ₂ aqueous solution) for 30 minutes in an environment of 50 ° C. After that, it is the peel strength measured under the conditions of a tensile speed of 300 mm / min and a peel angle of 180 degrees,
The adhesive strength F2 after immersion in the alkaline solution was obtained by immersing a 5 mm wide adhesive sheet attached to a stainless steel plate as an adherend in an aqueous sodium hydroxide solution (50% NaOH aqueous solution) for 30 minutes in an environment of 50 ° C. After that, the display device is the peel strength measured under the conditions of a tensile speed of 300 mm/min and a peel angle of 180 degrees. A laminate comprising a metal member and an adhesive sheet attached to the surface of the metal member,
The pressure-sensitive adhesive sheet is a double-sided adhesive pressure-sensitive adhesive sheet having a thickness of 100 μm or less,
The pressure-sensitive adhesive sheet has an acrylic pressure-sensitive adhesive layer containing an acrylic polymer,
The pressure-sensitive adhesive sheet has a 180-degree peel strength F0 of 3.0 N/5 mm or more against a stainless steel plate measured at a tensile speed of 300 mm/min,
The pressure-sensitive adhesive sheet has both an adhesive strength retention rate after immersion in an acidic solution and an adhesive strength retention rate after immersion in an alkaline solution of 80% or more,
The adhesive strength retention rate after immersion in the acidic solution [%] is obtained from the ratio (F1/F0 × 100) of the adhesive strength after immersion in the acidic solution F1 [N/5 mm] to the peel strength F0 [N/5 mm]. The adhesive strength retention rate after immersion in alkaline solution [%] is obtained from the ratio (F2 / F0 × 100) of the adhesive strength after immersion in alkaline solution F2 [N / 5 mm] to the peel strength F0 [N / 5 mm].
The adhesive strength F1 after immersion in the acidic solution was obtained by immersing a 5 mm wide adhesive sheet attached to a stainless steel plate as an adherend in an aqueous iron chloride solution (5% FeCl ₂ aqueous solution) for 30 minutes in an environment of 50 ° C. After that, it is the peel strength measured under the conditions of a tensile speed of 300 mm / min and a peel angle of 180 degrees,
The adhesive strength F2 after immersion in the alkaline solution was obtained by immersing a 5 mm wide adhesive sheet attached to a stainless steel plate as an adherend in an aqueous sodium hydroxide solution (50% NaOH aqueous solution) for 30 minutes in an environment of 50 ° C. After that, the laminate, which is the peel strength measured under the conditions of a tensile speed of 300 mm/min and a peel angle of 180 degrees.

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