JP2023000824A - Adhesive sheet, display device, laminate, and adhesive composition - Google Patents

Abstract

To provide an adhesive sheet capable of concealing an adherend and achieving excellent infrared ray shielding.SOLUTION: There is provided an adhesive sheet having an adhesive layer. The adhesive layer comprises an infrared absorbent and a coloring agent other than the infrared absorbent.SELECTED DRAWING: Figure 1

Description

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

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 easily adhering to adherends under pressure. Taking advantage of such properties, pressure-sensitive adhesives are widely used in various applications for the purpose of joining, fixing, and protecting members in mobile electronic devices such as mobile phones. For example, an adhesive having a light-shielding adhesive layer for the purpose of preventing light leakage from light sources such as backlight modules of liquid crystal display devices in mobile electronic devices such as mobile phones and self-luminous elements such as organic EL (electroluminescence). sheet is used. For the purpose of concealing the adherend, etc., a pressure-sensitive adhesive sheet having a predetermined light-shielding property is used. Japanese Patent Laid-Open No. 2002-200010 is cited as a document related to this type of technology.

In addition, for the purpose of absorbing and shielding near-infrared rays (wavelength 800 to 1100 nm) emitted from the plasma display, an adhesive containing composite tungsten oxide fine particles represented by the general formula MxWyOz, or using the adhesive Adhesive films with high transparency are known. Documents relating to this type of technology include Patent Documents 2 to 4.

JP-A-2002-235053 JP 2018-9053 A JP 2011-65146 A WO2009/020207

The light-shielding pressure-sensitive adhesive sheet covers the entire visible-side surface of the adherend to achieve the purpose of concealing the adherend. For example, a pressure-sensitive adhesive sheet used on the back side of an organic EL panel or the like is visible when the illumination of the display section is turned off, so it is required to conceal the adherend with good appearance quality. For such applications, a highly light-shielding pressure-sensitive adhesive sheet using a black colorant such as carbon black is preferably used.

By the way, in various devices such as the above-mentioned portable electronic devices, infrared rays, visible light, and ultraviolet rays are used for personal authentication, device operation, detection of nearby objects, detection of ambient brightness (environmental light), data communication, etc. An optical sensor that utilizes light rays such as a light beam is used. For example, an infrared sensor may be used in a biometrics authentication technology that authenticates an individual based on biometric information such as fingerprints and veins. In such a device, infrared rays from the outside become noise, and there is a risk of degrading the operating accuracy of the sensor. Further, in a device such as a remote control (remote controller) that uses an infrared sensor to operate the main body, it is undesirable for infrared rays to leak from a light-emitting portion other than a light-emitting portion directed toward an object.

In a device having an infrared sensor as described above, a light-shielding adhesive sheet that is used by being attached to an infrared-shielding material (adherend) such as a metal is usually used because the adherend can shield infrared rays. It need not itself be infrared blocking. In addition, since the light-shielding pressure-sensitive adhesive sheet can also block infrared rays by blocking visible light by using a black colorant or the like, there is no need to take additional means for blocking infrared rays. However, in mobile electronic devices, for example, members covered by adhesive sheets may be processed in order to impart new functions, etc., and the adhesive sheet attached to such members may not be A mode of use is envisioned in which the surface of an adherend is covered, including a region where the adherend member does not partially exist, to conceal the adherend. In such a usage mode, even if the adhesive sheet is capable of sufficiently shielding visible light, infrared rays may pass through the adhesive sheet and the non-adherend region if the infrared shielding property is not sufficient. As a cause, there is a possibility that malfunction of the optical sensor or the like occurs. For example, conventional light-shielding pressure-sensitive adhesive sheets using a black colorant such as carbon black can block infrared rays in the near-infrared region (800 to 1100 nm), but the infrared-ray blocking property decreases in the wavelength region longer than 1100 nm. However, it does not necessarily have sufficient infrared shielding properties. In addition, in the new usage pattern as described above, higher infrared shielding properties than those of conventional light-shielding pressure-sensitive adhesive sheets may be required. If a pressure-sensitive adhesive sheet having excellent infrared shielding properties in addition to covering an adherend is provided, infrared rays can be shielded regardless of the material or shape of the adherend, which is of practical significance.

The present invention was created in view of the above circumstances, and an object of the present invention is to provide a pressure-sensitive adhesive sheet capable of concealing an adherend and excellent infrared shielding. Another related object is to provide a display device and a laminate having the adhesive sheet. Yet another related object is to provide a pressure-sensitive adhesive composition that is used to form the pressure-sensitive adhesive of the pressure-sensitive adhesive sheet.

According to this specification, a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer containing an infrared absorbing agent and a coloring agent different from the infrared absorbing agent is provided. According to the above configuration, by selecting an appropriate type of infrared absorbing agent and coloring agent and including them in an appropriate amount in the adhesive, the adherend can be concealed and infrared rays can be shielded. Moreover, by using the infrared absorbing agent and the coloring agent in combination, it is possible to achieve infrared shielding that is superior to the case where the infrared absorbing agent is used alone. According to the above pressure-sensitive adhesive sheet, it is possible to prevent problems caused by the passage of infrared rays, such as a decrease in operating accuracy and malfunction of an infrared sensor, regardless of the material and shape of the adherend.

In some embodiments, the infrared absorber is a metal compound. By using a metal compound as an infrared absorber, the effects of the technology disclosed herein are preferably achieved.

In some preferred embodiments, the infrared absorber is selected from tungsten composite oxides and tin composite oxides. By using at least one selected from tungsten composite oxides and tin composite oxides as the infrared absorber, it is possible to have adherend-hiding properties and achieve excellent infrared shielding. Specifically, by using a tungsten composite oxide and/or a tin composite oxide, not only near-infrared rays (800 to 1100 nm) but also infrared rays with a wavelength longer than 1100 nm can be sufficiently shielded.

In some preferred embodiments, the colorant comprises a black colorant. By using a black colorant as the colorant, the adherend-hiding property can be achieved with a small amount of the colorant used. In addition, the infrared transmittance can be efficiently reduced by using a black colorant. This is significant in terms of preventing or suppressing deterioration in adhesive properties due to inclusion of a coloring agent or the like.

In some embodiments, the colorant further comprises a metal oxide. By using a metal oxide in addition to a black colorant as a colorant, the light that is about to enter the adhesive is reflected to reduce the visible light transmittance, and this effect is used to conceal the adherend. can do.

In some preferred embodiments, the total amount of the infrared absorbing agent and the colorant contained in the pressure-sensitive adhesive layer is in the range of 5 to 30 parts by weight with respect to 100 parts by weight of the base polymer contained in the pressure-sensitive adhesive layer. is. By adjusting the total amount of the infrared absorber and the colorant to 5 to 30 parts by weight based on 100 parts by weight of the base polymer, it is possible to effectively conceal the target adherend and shield the infrared rays while maintaining good adhesive properties. can be realized.

In some preferred embodiments, the pressure-sensitive adhesive layer is an acrylic pressure-sensitive adhesive layer containing an acrylic polymer as a base polymer. The technology disclosed herein is preferably implemented in a configuration including an acrylic pressure-sensitive adhesive layer.

In some preferred embodiments, the adhesive layer has a thickness in the range of 10-50 μm. By setting the thickness of the pressure-sensitive adhesive layer to 10 μm or more, it is possible to preferably realize adherend concealment and infrared shielding. In addition, there is a tendency to easily realize desired adhesive properties. By setting the thickness of the pressure-sensitive adhesive layer to 50 μm or less, it is possible to meet the demands for thinning and lightening.

The pressure-sensitive adhesive sheet according to some preferred embodiments 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. Moreover, according to the technology disclosed herein, it is possible to achieve concealment of the adherend and infrared shielding based on the structure of the pressure-sensitive adhesive without relying on the base material. Furthermore, according to the substrate-less pressure-sensitive adhesive sheet, the effects of the pressure-sensitive adhesive layer, such as adhesive strength and impact resistance, can be maximized.

In addition, the pressure-sensitive adhesive sheet disclosed herein preferably has a 180-degree peel strength to a stainless steel plate measured according to JIS Z 0237 of 10 N/25 mm or more. According to the technology disclosed herein, it is possible to realize a pressure-sensitive adhesive sheet that has an adherend-hiding property, an infrared shielding property, and an adhesive strength equal to or greater than a predetermined value. The pressure-sensitive adhesive sheet having the above adhesive strength can fix an adherend with higher adhesive strength.

Since the pressure-sensitive adhesive sheet disclosed herein can conceal an adherend, it is preferably used in various applications where concealment of an adherend is required, taking advantage of this feature. For example, it can be preferably used for fixing members of portable electronic devices. The above-mentioned portable electronic devices may require concealment of members, and it is significant to apply the pressure-sensitive adhesive sheet disclosed herein. In addition, since portable electronic devices may incorporate optical sensors such as infrared sensors, it is particularly important to ensure the operation accuracy of the optical sensors by blocking infrared rays using the adhesive sheet disclosed herein. Meaningful. For example, it is suitable for fixing a member of a portable electronic device containing an infrared sensor.

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, an adhesive sheet is attached to the support portion. Further, the pressure-sensitive adhesive sheet has a pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer contains an infrared absorbing agent and a coloring agent different from the infrared absorbing agent. The pressure-sensitive adhesive sheet disclosed herein is preferably used as a component (for example, 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 has an adhesive layer. Further, the pressure-sensitive adhesive layer contains an infrared absorbing agent and a coloring agent different from the infrared absorbing agent. According to the above configuration, the adhesive sheet can conceal the metal member by covering the metal member. In addition, the metal member may have an infrared blocking property, but if the metal member is processed such as opening, the pressure-sensitive adhesive sheet may to hide the adherend. In such a case, since the infrared rays can pass through the pressure-sensitive adhesive sheet and the area where the adherend is not present, there is concern about the occurrence of problems caused by the infrared rays. According to the laminate, the infrared shielding property of the pressure-sensitive adhesive sheet can be used to shield infrared rays over the entire sheet surface including the metal member absent region.

In addition, according to this specification, a laminate including a member having optical transparency and an adhesive sheet is provided. In this laminate, one surface of the pressure-sensitive adhesive sheet is attached to the light-transmitting member. Further, the pressure-sensitive adhesive sheet has a pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer contains an infrared absorbing agent and a coloring agent different from the infrared absorbing agent. According to the above configuration, infrared rays can pass through the light-transmitting member, but the presence of the adhesive sheet attached to the light-transmitting member makes it possible to shield the entire laminate from infrared rays. For example, in a mode in which the pressure-sensitive adhesive sheet is a double-sided pressure-sensitive adhesive sheet, when the pressure-sensitive adhesive surface of the pressure-sensitive adhesive sheet opposite to the side on which the light-transmitting member is adhered is adhered to an adherend, the laminate is The adhesive sheet can cover the adherend and shield infrared rays that have passed through the light-transmitting member.

This specification also provides a pressure-sensitive adhesive composition containing an infrared absorbing agent and a coloring agent different from the infrared absorbing agent. By using the pressure-sensitive adhesive composition having the composition described above, more specifically, by selecting and using an appropriate type and amount of infrared absorber and colorant to prepare the pressure-sensitive adhesive composition disclosed herein. A pressure-sensitive adhesive sheet can be produced. In other words, by using the PSA composition disclosed herein, a PSA sheet capable of concealing an adherend and shielding against infrared rays can be produced.

1 is a cross-sectional view schematically showing one configuration example of an adhesive sheet; FIG. 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. 4 is a graph showing the light transmittance in the wavelength range of 380 to 1500 nm of the pressure-sensitive adhesive sheet according to each example.

Preferred embodiments of the present invention are described below. Matters other than the matters specifically mentioned in the present specification and matters 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 drawings below, 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).

<Configuration example of adhesive sheet>
The pressure-sensitive adhesive sheet disclosed herein may be a pressure-sensitive adhesive sheet with a substrate having the above-mentioned pressure-sensitive adhesive layer on one or both sides of a non-releasable substrate (supporting substrate). It may be a substrate-less pressure-sensitive adhesive sheet (that is, a pressure-sensitive adhesive sheet having no non-releasable substrate) such as a form held by a liner. The concept of the adhesive sheet as used herein can include what is called an adhesive tape, an adhesive label, an adhesive film, and the like. The pressure-sensitive adhesive sheet disclosed herein may be roll-shaped or sheet-shaped. 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). In the pressure-sensitive adhesive sheet 1 shown in FIG. 1, both surfaces 21A and 21B of the base-less pressure-sensitive adhesive layer 21 (which are also the pressure-sensitive adhesive surfaces 1A and 1B of the pressure-sensitive adhesive sheet 1, respectively) serve as release surfaces at least on the pressure-sensitive adhesive layer side. The structure is protected by release liners 31 and 32, respectively. 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 so. 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.

<Adhesive layer>
(base polymer)
In the technology disclosed herein, the type of adhesive that constitutes the adhesive layer is not particularly limited. The adhesives include acrylic polymers, rubber polymers (natural rubber, synthetic rubber, mixtures thereof, etc.), polyester polymers, urethane polymers, polyether polymers, silicone polymers, which can be used in the field of adhesives. It may contain one or more of various rubber-like polymers such as polyamide-based polymers and fluorine-based polymers as an adhesive polymer (in the sense of a structural polymer that forms an adhesive, hereinafter also referred to as "base polymer"). . From the viewpoint of adhesive performance, cost, etc., a pressure-sensitive adhesive containing an acrylic polymer or a rubber-based polymer as a base polymer can be preferably employed. Among them, a pressure-sensitive adhesive having an acrylic polymer as a base polymer (acrylic pressure-sensitive adhesive) is preferable. The technique disclosed here is preferably implemented in a mode using an acrylic pressure-sensitive adhesive.

A pressure-sensitive adhesive layer composed of an acrylic pressure-sensitive adhesive, that is, a pressure-sensitive adhesive sheet having an acrylic pressure-sensitive adhesive layer will be mainly described below. It is not intended to be limited to

The "base polymer" of the pressure-sensitive adhesive refers to the main component of the rubber-like polymer contained in the pressure-sensitive adhesive, and is not to be construed as being limited to anything other than this. The term "rubber-like polymer" refers to a polymer that exhibits rubber elasticity in a temperature range around room temperature. In this specification, the term "main component" refers to a component contained in an amount exceeding 50% by weight unless otherwise specified.
Further, 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 monomer units constituting the polymer. Hereinafter, a monomer having at least one (meth)acryloyl group in one molecule is also referred to as "acrylic monomer". Accordingly, an acrylic polymer in this specification is defined as a polymer containing monomeric units derived from an acrylic monomer. A typical example of an acrylic polymer is an acrylic polymer containing more than 50% by weight of the acrylic monomer in the total monomer components used to synthesize the acrylic polymer.
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.

(acrylic polymer)
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 "C _1-20 ". From the viewpoint of the storage elastic modulus of the adhesive, an alkyl (meth)acrylate in which R ² is a C _1-14 (for example, C _1-10 , typically C _4-8 ) chain alkyl group is used as the main monomer. It is appropriate to From the viewpoint of adhesive properties, the main monomer is an alkyl acrylate in which R ¹ is a hydrogen atom and R ² is a C _4-8 chain alkyl group (hereinafter also simply referred to as C _4-8 alkyl acrylate). is preferred.

Specific examples of alkyl (meth)acrylates in which R ² is a C _1-20 chain alkyl group include, but are not limited to, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) ) acrylate, heptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate ) 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. These alkyl (meth)acrylates may be used singly or in combination of two or more. Suitable examples of alkyl (meth)acrylates include n-butyl acrylate (BA) and 2-ethylhexyl acrylate (2EHA).

The ratio of the alkyl (meth)acrylate to the monomer components constituting the acrylic polymer is typically more than 50% by weight, and can be, for example, 70% by weight or more, and may be 85% by weight or more, or 90% by weight. % by weight or more. Although the upper limit of the proportion of alkyl (meth)acrylate is not particularly limited, it is preferably 99.5% by weight or less (for example, 99% by weight or less), or properties based on submonomers such as carboxy group-containing monomers (for example, aggregation 98% by weight or less (for example, less than 97% by weight) from the viewpoint of preferably exerting force). Alternatively, the acrylic polymer may be obtained by polymerizing substantially only alkyl (meth)acrylate.

Further, when C _4-8 alkyl acrylate is used as a monomer component, the proportion of C _4-8 alkyl acrylate in the alkyl (meth)acrylate contained in the monomer component is preferably 70% by weight or more, It is more preferably 90% by weight or more. The C _4-8 alkyl acrylates can be used singly or in combination of two or more.

The technique disclosed herein can be preferably carried out in a mode in which the monomer component constituting the acrylic polymer contains 50% by weight or more of C _1-6 alkyl (meth)acrylate. In other words, the polymerization ratio of C _1-6 alkyl (meth)acrylate in the acrylic polymer is preferably 50% by weight or more. The proportion of C _1-6 alkyl (meth)acrylate in the monomer component (in other words, polymerization proportion) is more preferably greater than 50% by weight, still more preferably 60% by weight or more, and particularly preferably 70% by weight or more (for example, 80% by weight or more, further 85% by weight or more). By using a predetermined amount or more of C _1-6 alkyl (meth)acrylate (for example, BA), a coloring agent such as a black coloring agent (for example, carbon black) is well dispersed in the pressure-sensitive adhesive layer, and adhesion strength and the like are improved. Good adhesion properties can be maintained. The upper limit of the ratio of C _1-6 alkyl (meth)acrylate in the monomer component is not particularly limited, and may be, for example, 99% by weight or less. % by weight or less. The C _1-6 alkyl (meth)acrylates may be used singly or in combination of two or more. The C _1-6 alkyl (meth)acrylate is preferably a C _1-6 alkyl acrylate, more preferably a C _2-6 alkyl acrylate, and still more preferably a C _4-6 alkyl acrylate. In some other embodiments, the C _1-6 alkyl (meth)acrylate is preferably a C _1-4 alkyl acrylate, more preferably a C _2-4 alkyl acrylate. A preferred example of the C _1-6 alkyl (meth)acrylate is BA.

In embodiments using BA as the main monomer, the copolymerization ratio of BA in the acrylic polymer is preferably greater than 50% by weight, more preferably 70% by weight or more, and still more preferably 90% by weight or more (e.g., more than 90% by weight). ). By copolymerizing BA as the main monomer, the pressure-sensitive adhesive tends to have good adhesion to adherends. By using a predetermined amount or more of BA, a coloring agent such as a black coloring agent (for example, carbon black) can be well dispersed in the adhesive layer, and adhesive properties such as adhesive strength can be maintained satisfactorily. Further, the copolymerization ratio of BA in the acrylic polymer is not particularly limited, and may be, for example, 99% by weight or less. good.

A secondary monomer may be 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-containing sub-monomer that introduces 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. Examples include 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, and imide group-containing monomers. 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 appropriately 40% by weight or less, and is 20% by weight or less. is preferable, and it may be 10% by weight or less (for example, 5% by weight or less).

Acrylic polymers according to some preferred embodiments may contain a carboxy group-containing monomer as a monomer component constituting the acrylic polymer. When the monomer component contains a carboxyl group-containing monomer, it becomes easier to obtain a pressure-sensitive adhesive sheet exhibiting good pressure-sensitive adhesive properties (cohesive strength, etc.). In addition, it can be advantageous for improving the adhesion between the pressure-sensitive adhesive layer and the adherend. Furthermore, by copolymerizing an appropriate amount of a carboxy group-containing monomer, a coloring agent such as a black coloring agent (e.g., carbon black) can be easily dispersed well in the adhesive layer, and adhesive properties can be preferably maintained. .

Examples of carboxy group-containing monomers include acrylic acid (AA), methacrylic acid (MAA), carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid. be done. 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.

In the embodiment in which the carboxy group-containing monomer is copolymerized with the acrylic polymer, the content of the carboxy group-containing monomer in the monomer component constituting the acrylic polymer is not particularly limited, and is, for example, 0.2 weight of the monomer component. % or more (typically 0.5 wt % or more), suitably 1 wt % or more, 2 wt % or more, or 3 wt % or more. By setting the content of the carboxy group-containing monomer to more than 3% by weight, higher effects are exhibited. In some embodiments, the content of the carboxyl group-containing monomer can be 3.2% by weight or more of the monomer component, and can be 3.5% by weight or more, or can be 4% by weight or more. It is good also as 5 weight% or more. The upper limit of the content of the carboxy group-containing monomer is not particularly limited, and may be, for example, 15% by weight or less, 12% by weight or less, or 10% by weight or less. The technology disclosed herein is used when the content of the carboxy group-containing monomer is 7% by weight or less (typically less than 7% by weight, such as 6.8% by weight or less, or 6.0% by weight or less) of the monomer component. A certain aspect can also be preferably implemented.

When a carboxy group-containing monomer is used as a copolymerization component (specifically, a functional group-containing monomer) of the acrylic polymer, 10% by weight or more of the functional group-containing monomer used may be the carboxy group-containing monomer. As a result, the cohesive force of the carboxyl group, the function as a cross-linking point, the dispersibility of the colorant, and the like can be favorably exhibited. From the viewpoint of better exhibiting the effect of copolymerizing the carboxy group-containing monomer, the ratio of the carboxy group-containing monomer to the total functional group-containing monomer is appropriately 30% by weight or more, preferably 50% by weight or more, and more. It is preferably 70% by weight or more, more preferably 90% by weight or more, for example, may be 97% by weight or more, may be 98% by weight or more, or may be 99% by weight or more (for example, 99.9% by weight or more). . The upper limit of the ratio of the carboxy group-containing monomer to the total functional group-containing monomer is 100% by weight, and may be, for example, 95% by weight or less.

In some other embodiments, an acrylic polymer copolymerized with a hydroxyl group-containing monomer may be used as the secondary monomer. 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.

In addition, when a hydroxyl group-containing monomer is used as the submonomer, its content is usually appropriate to be about 0.001% by weight or more of the total monomer components, and about 0.01% by weight or more (typically may be about 0.02% by weight or more). In addition, the content of the hydroxyl group-containing monomer is suitably less than 15% by weight, preferably about 8% by weight or less, more preferably about 3% by weight or less (for example, less than 1% by weight) in the total monomer components. is. Moreover, the technology disclosed herein can be implemented using a pressure-sensitive adhesive containing an acrylic polymer in which a hydroxyl group-containing monomer is not copolymerized.

In some other embodiments, an acrylic polymer obtained by copolymerizing a nitrogen atom-containing monomer may be used as the secondary monomer. Preferred examples of nitrogen atom-containing monomers include nitrogen atom-containing ring-containing monomers (N-vinyl-2-pyrrolidone, N-(meth)acryloylmorpholine, etc.). A monomer having a nitrogen atom can be used alone or in combination of two or more.

When a monomer having a nitrogen atom (preferably a monomer having a nitrogen atom-containing ring) is used as the secondary monomer, the content is not particularly limited, and may be, for example, 1% by weight or more of the total monomer components, or 3% by weight. % or more, and may be 5% by weight or more or 7% by weight or more. In addition, the amount of the monomer having a nitrogen atom used is, for example, less than 20% by weight of the total monomer components, and may be less than 10% by weight, may be less than 3% by weight, or may be less than 1% by weight. good too. The technology disclosed herein can be implemented using a pressure-sensitive adhesive containing an acrylic polymer in which a nitrogen atom-containing monomer is not copolymerized.

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 amount of such other copolymerization components may be appropriately selected according to the purpose and application and is not particularly limited, but from the viewpoint of appropriately exhibiting the effects of use, it is suitable to be 0.05% by weight or more. , 0.5% by weight or more. In addition, from the viewpoint of easily balancing adhesive performance, the content of other copolymerization components in the monomer component is suitably 20% by weight or less, and 10% by weight or less (for example, 5% by weight or less, and further is 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 copolymer composition of the acrylic polymer is suitably designed so that the glass transition temperature (Tg) of the polymer is approximately −15° C. or lower (for example approximately −70° C. or higher and −15° C. or lower). Here, the Tg of the acrylic polymer refers to the Tg determined by the Fox formula based on the composition of the monomer components used in synthesizing the polymer. The Fox equation is a relational expression between the Tg of a copolymer and the glass transition temperature Tgi of a homopolymer obtained by homopolymerizing each of the monomers constituting the copolymer, as shown below.
1/Tg=Σ(Wi/Tgi)
In the above Fox formula, Tg is the glass transition temperature of the copolymer (unit: K), Wi is the weight fraction of the monomer i in the copolymer (copolymerization ratio based on weight), and Tgi is the content of the monomer i. It represents the glass transition temperature (unit: K) of a homopolymer.

As the glass transition temperature of the homopolymer used for calculating Tg, the numerical value described in a publicly known document, specifically "Polymer Handbook" (3rd edition, John Wiley & Sons, Inc., 1989) shall be used. . For monomers for which multiple values are listed in this document, the highest value is adopted. If it is not described in the above Polymer Handbook, the value obtained by the measurement method described in JP-A-2007-51271 shall be used.

Although not particularly limited, the Tg of the acrylic polymer is advantageously about −25° C. or less, preferably about −35° C. or less, from the viewpoint of impact resistance and adhesion to adherends. , more preferably about −40° C. or lower. In some embodiments, from the viewpoint of cohesive strength, the Tg of the acrylic polymer is, for example, approximately −70° C. or higher, may be approximately −65° C. or higher, may be approximately −60° C. or higher, or may be approximately −55° C. or higher. good. The technology disclosed herein can be preferably carried out in a mode in which the Tg of the acrylic polymer is approximately −65° C. or higher and −35° C. or lower (for example, approximately −55° C. or higher and −40° C. or lower). The Tg of the acrylic polymer can be adjusted by appropriately changing the monomer composition (that is, the types and usage ratio of the monomers used in synthesizing the polymer).

The method for obtaining the acrylic polymer is not particularly limited, and various polymerization methods known as synthesis methods for acrylic polymers, such as solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization, and photopolymerization. can be adopted as appropriate. 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 weight-average molecular weight (Mw) of the base polymer (preferably acrylic polymer) in the technology disclosed herein is not particularly limited, and can range, for example, from about 10×10 ⁴ to 500×10 ⁴ . From the viewpoint of adhesion performance, the Mw of the base polymer is about 30×10 ⁴ to 200×10 ⁴ (more preferably about 45×10 ⁴ to 150×10 ⁴ , typically about 65×10 ⁴ to 130×10 ⁴ ) is preferably within the range. By using a base polymer with a high Mw, there is a tendency to obtain better impact resistance by utilizing the cohesive force of the polymer itself. 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.

(coloring agent)
The adhesive layer disclosed herein is characterized by containing a colorant. By including a colorant in the pressure-sensitive adhesive layer, the pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer can cover the adherend. Moreover, by using the infrared absorbing agent and the colorant in combination, it is possible to realize superior infrared shielding compared to the case of using the infrared absorbing agent alone. The colorant is defined as a coloring component that does not correspond to the infrared absorber described later, and various materials that can attenuate light traveling in the adhesive layer by absorbing it, or reduce the amount of light entering the adhesive layer. A variety of available materials can be used. Colorants can be, for example, black, gray, white, red, blue, yellow, green, yellow-green, orange, purple, gold, silver, pearlescent colorants, and the like. The colorant can be contained in the pressure-sensitive adhesive layer typically in a state of being dispersed (or may be in a dissolved state) in the constituent materials of the pressure-sensitive adhesive layer. Conventionally known pigments and dyes can be used as the colorant. Pigments include inorganic pigments and organic pigments. Colorants may be used singly or in combination of two or more. By using two or more kinds of colorants, the adherend-hiding property can be improved.

The colorant contained in the pressure-sensitive adhesive layer is not particularly limited, but is, for example, a component capable of absorbing and attenuating light traveling through the pressure-sensitive adhesive layer. and can be a component that reduces the light transmittance of the pressure-sensitive adhesive layer. As such a coloring agent (hereinafter also referred to as a "first coloring agent"), a black coloring agent can be preferably used because the concealing property can be efficiently adjusted with the use of a small amount. Also, by using a black colorant and an infrared absorber together, the infrared transmittance can be efficiently reduced. Specific examples of black colorants include carbon black, graphite, aniline black, perylene black, cyanine black, titanium black, inorganic pigment hematite, activated carbon, molybdenum disulfide, chromium complexes, and anthraquinone colorants. Black colorants may be used singly or in appropriate combination of two or more.

In some preferred embodiments, the adhesive layer contains carbon black particles as a colorant (first colorant). As carbon black particles to be used, those generally called carbon black (furnace black, channel black, acetylene black, thermal black, lamp black, pine smoke, etc.) can be used without particular limitation. 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 (for example, 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.

Particulate colorants (pigments) can be preferably used because they can efficiently adjust the hiding power with the use of a small amount. 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 colorant is appropriately about 500 nm or less, preferably about 300 nm or less, more preferably about 250 nm or less, still more preferably about 200 nm or less (for example, about 120 nm or less, furthermore approximately 100 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.

In the embodiment in which the pressure-sensitive adhesive layer contains the first coloring agent, the content of the first coloring agent (preferably a black coloring agent such as carbon black particles) is determined according to the adherend hiding property to be achieved and the adhesive properties required. etc., and is not limited to a specific range. In addition, the content of the first coloring agent may vary depending on the type of adhesive, the shape and particle size of the first coloring agent, compatibility with the adhesive, and the like. The content of the first coloring agent in the pressure-sensitive adhesive layer is suitably about 0.01% by weight or more (for example, 0.05% by weight or more), and from the viewpoint of the adherend hiding property, preferably about 0. .1 wt% or more, more preferably about 0.2 wt% or more, may be about 0.3 wt% or more, for example about 0.5 wt% or more, 0.7 wt% % or more. In some aspects, the content of the first colorant is suitably about 1% by weight or more (eg, more than 1% by weight), preferably about 2% by weight or more, and about 2.5% by weight or more. % by weight or more, or 3% by weight or more. By increasing the amount of the first colorant used, the infrared transmittance can also be effectively reduced. Further, in the aspect in which the pressure-sensitive adhesive layer contains the first coloring agent or the aspect in which the pressure-sensitive adhesive layer does not contain the first coloring agent, the content of the first coloring agent (preferably a black coloring agent such as carbon black particles) is about 10% by weight. %, suitably about 7% by weight or less, preferably about 6% by weight or less, more preferably about 5% by weight or less, even more preferably about 4% by weight or less, and about 3% by weight. It may be below. In some aspects, the content of the first colorant may be about 2 wt% or less (typically less than 2 wt%), may be about 1 wt% or less, and more preferably about 0 0.6% by weight or less, and may be approximately 0.5% by weight or less (for example, 0.3% by weight or less). By limiting the content of the first coloring agent, there is a tendency to easily maintain adhesive properties such as adhesive strength. According to the technology disclosed herein, it is possible to achieve the desired adherend-concealability even in the configuration in which the amount of the first coloring agent used is limited as described above.

The content of the first coloring agent (preferably a black coloring agent such as carbon black particles) can also be specified by its relative relationship with the amount of base polymer. In some embodiments, the content of the first colorant is, for example, 0.01 parts by weight or more, and suitably 0.05 parts by weight or more, relative to 100 parts by weight of the base polymer (preferably acrylic polymer). From the viewpoint of the adherend hiding property, it is preferably about 0.1 parts by weight or more, more preferably about 0.2 parts by weight or more, still more preferably about 0.3 parts by weight or more, for example about 0.3 parts by weight. It may be 5 parts by weight or more, or may be 0.8 parts by weight or more. In some other embodiments, the content of the first colorant is about 1 part by weight or more (for example, more than 1 part by weight) relative to 100 parts by weight of the base polymer. It may be 2 parts by weight or more, more preferably about 2.5 parts by weight or more. By increasing the amount of the first coloring agent used, the infrared transmittance can also be effectively reduced. In addition, in the aspect in which the adhesive layer contains the first coloring agent or the aspect in which the pressure-sensitive adhesive layer does not contain the first coloring agent, the content of the first coloring agent (preferably a black coloring agent such as carbon black particles) is Preferably, it can be about 10 parts by weight or less, preferably about 7 parts by weight or less, preferably less than 6 parts by weight, more preferably about 5 parts by weight or less, based on 100 parts by weight of the acrylic polymer). , more preferably about 4 parts by weight or less, and may be about 3.5 parts by weight or less. In some aspects, the content of the first colorant is about 3 parts by weight or less (typically less than 3 parts by weight), and about 2 parts by weight or less, relative to 100 parts by weight of the base polymer. may be about 1.5 parts by weight or less, or about 1 part by weight or less (for example, 0.6 parts by weight or less). By limiting the content of the first coloring agent, there is a tendency to easily maintain adhesive properties such as adhesive strength.

In some other aspects, the pressure-sensitive adhesive layer can be implemented in an aspect that includes, as a coloring agent, the second coloring agent described below (for example, the metal oxide described below). For example, in embodiments in which the pressure-sensitive adhesive layer contains at least two coloring agents, at least one of the plurality of coloring agents may be the first coloring agent described above or the second coloring agent described below. In the aspect in which the pressure-sensitive adhesive layer contains at least two kinds of colorants, the above-described first colorant and second colorant may be used in combination.

The second coloring agent that can be used in the technique disclosed herein is not particularly limited, but is, for example, a component that can reduce the amount of light entering the adhesive layer, It can be a component that increases the light reflectance of the adhesive layer by being contained in the adhesive layer. Such a second colorant may be one or more selected from inorganic materials (eg, metals, metal compounds), organic materials, and organic-inorganic composites. Specific examples of the second coloring agent include titanium oxide (titanium dioxide such as rutile-type titanium dioxide and anatase-type titanium dioxide), zinc oxide, cerium oxide, aluminum oxide, silicon oxide, zirconium oxide, magnesium oxide, calcium oxide, oxide Metal oxides such as tin, barium oxide, cesium oxide, yttrium oxide; carbonate compounds such as magnesium carbonate, calcium carbonate (light calcium carbonate, ground calcium carbonate, etc.), barium carbonate, zinc carbonate; aluminum hydroxide, calcium hydroxide , magnesium hydroxide, hydroxide such as zinc hydroxide; silicate compounds such as aluminum silicate, magnesium silicate, calcium silicate; barium sulfate, calcium sulfate, barium stearate, zinc white, zinc sulfide, talc, clay, kaolin, phosphoric acid Inorganic materials such as titanium, mica, gypsum, white carbon, diatomaceous earth, bentonite, lithopone, zeolite, sericite, and hydrated halloysite; acrylic resins, polystyrene resins, polyurethane resins, amide resins, polycarbonate resins, Organic materials such as silicone-based resins, urea-formalin-based resins, and melamine-based resins can be used. These may be referred to as white colorants. The second coloring agent can be used singly or in combination of two or more. Note that the second colorant may be defined as a colorant that does not contain carbon black particles and is different from carbon black particles. Typically, the second colorant does not include a light absorbing black colorant.

In some preferred embodiments, the adhesive layer contains a metal oxide as the second colorant. By using a first coloring agent (preferably a black coloring agent) and a metal oxide together, the amount of light entering the adhesive layer is reduced, and the light entering the adhesive layer is absorbed to transmit visible light. rate and improve the adherend-hiding property. As the metal oxide, a material capable of realizing a desired adherend-hiding property can be selected from the materials described above. Preferred examples include titanium oxide, zinc oxide, cerium oxide, aluminum oxide, silicon oxide, zirconium oxide, magnesium oxide, and calcium oxide. Among them, titanium oxide, silicon oxide, and zirconium oxide are preferred, and titanium oxide is particularly preferred. preferable. A metal oxide can be used individually by 1 type or in combination of 2 or more types.

In the aspect in which the second coloring agent has a particle shape, the average particle size of the second coloring agent (preferably metal oxide particles) is not particularly limited. Depending on the thickness of the pressure-sensitive adhesive layer, the type of pressure-sensitive adhesive, and the like, particles having an appropriate size that can achieve the desired adherend-hiding property can be used. The average particle size of the second colorant can be, for example, about 1 nm or more, and about 5 nm or more is suitable. From the viewpoint of the effect of containing the second colorant (for example, reduction in visible light transmittance due to improvement in light reflectance), compatibility, handleability, etc., the average particle size of the second colorant is preferably about 10 nm or more, and about 20 nm. or more, or about 30 nm or more. The upper limit of the average particle size is, for example, about 300 nm or less from the viewpoint of maintaining adhesive properties, and preferably less than 100 nm (for example, 90 nm or less), more preferably approximately 70 nm or less, may be approximately 50 nm or less, or may be approximately 35 nm or less (for example, approximately 25 nm or less).

In the embodiment in which the pressure-sensitive adhesive layer contains the second coloring agent, the content of the second coloring agent (preferably metal oxide) in the pressure-sensitive adhesive layer is determined by the effect of containing the second coloring agent (for example, by improving the light reflectance Visible light transmittance reduction) and required adhesive properties are appropriately set, and the range is not limited to a specific range. In addition, the content of the second coloring agent may vary depending on the type of adhesive, the shape and particle size of the second coloring agent, compatibility with the adhesive, and the like. From the viewpoint of effectively obtaining the effect of containing the second coloring agent, the content of the second coloring agent in the pressure-sensitive adhesive layer is appropriately about 1% by weight or more, preferably about 3% by weight or more, more preferably about It may be 5% by weight or more, more preferably about 7% by weight or more. In addition, in the aspect in which the pressure-sensitive adhesive layer contains the second coloring agent or the aspect in which the pressure-sensitive adhesive layer does not contain the second coloring agent, the content of the second coloring agent in the pressure-sensitive adhesive layer depends on compatibility with the pressure-sensitive adhesive component, adhesive strength and resistance. From the viewpoint of maintaining adhesive properties such as impact resistance, it can be about 25% by weight or less, suitably about 20% by weight or less, preferably about 15% by weight or less, and about 12% by weight or less. may be about 10% by weight or less, or about 8% by weight or less. According to the technology disclosed herein, it is possible to achieve the desired adherend-concealability in the configuration in which the amount of the second coloring agent used is limited as described above.

The content of the second colorant (preferably metal oxide) can also be specified by its relative relationship with the amount of base polymer. The content of the second colorant is appropriately about 1 part by weight or more, preferably about 3 parts by weight or more, more preferably about 5 parts by weight, based on 100 parts by weight of the base polymer (preferably acrylic polymer). parts or more, more preferably about 8 parts by weight or more, and may be about 10 parts by weight or more. In addition, in the aspect in which the adhesive layer contains the second coloring agent or the aspect in which the adhesive layer does not contain the second coloring agent, the content of the second coloring agent determines compatibility with the adhesive component, adhesive strength, impact resistance, and the like. From the viewpoint of maintaining adhesive properties, etc., it can be about 30 parts by weight or less, suitably about 25 parts by weight or less, preferably about 20 parts by weight or less, more preferably about 20 parts by weight or less, with respect to 100 parts by weight of the base polymer. It is 15 parts by weight or less, may be approximately 12 parts by weight or less, or may be approximately 10 parts by weight or less.

In the embodiment in which the pressure-sensitive adhesive layer contains the first coloring agent and the second coloring agent, the use ratio of the amount C1 of the first coloring agent and the amount C2 of the second coloring agent achieves the desired adherend hiding property. and is not limited to any particular range. In some embodiments, the weight ratio (C1/C2) between the amount C1 of the first colorant (preferably black colorant) and the amount C2 of the second colorant (preferably metal oxide) is 0.001 0.005 or more, 0.01 or more, 0.03 or more, 0.05 or more, or 0.10 or more. As the weight ratio (C1/C2) increases, the effect of adding the first colorant is more preferably exhibited. In the embodiment in which the first coloring agent is a black coloring agent, the light-absorbing property of the adhesive layer tends to improve the light-shielding properties of the pressure-sensitive adhesive layer, and the infrared transmittance tends to decrease. In some embodiments, the weight ratio (C1/C2) is less than 1, such as 0.50 or less, or 0.40 or less (e.g., 0.35 or less), It is preferably 0.30 or less, may be 0.20 or less, may be 0.15 or less, may be 0.12 or less, may be 0.09 or less, or may be 0.06 or less (for example, 0.05 or less ). The smaller the weight ratio (C1/C2), the better the effect of adding the second colorant. In the embodiment in which the second colorant is a metal oxide, the light reflectance of the pressure-sensitive adhesive layer is improved, and there is a tendency for the adherend-hiding property to be easily obtained.

In the aspect in which the pressure-sensitive adhesive layer contains a black colorant as the first colorant and/or a metal oxide as the second colorant, the content of colorants other than the black colorant and the metal oxide is particularly limited. may be less than 30% by weight, preferably less than 10% by weight, may be less than 5.0% by weight, may be less than 3.0% by weight, such as less than 2.0% by weight, or even less than 1% by weight). The technology disclosed herein can be practiced in a mode provided with a pressure-sensitive adhesive layer that does not substantially contain any colorant other than a black colorant and a metal oxide. In this specification, "substantially free" means not intentionally added, for example, the content in the pressure-sensitive adhesive layer is 0.3% by weight or less (e.g., 0.1% by weight or less, typically 0.01% by weight or less).

As the colorant, from the viewpoint of compatibility with the adhesive component, the material (particulate colorant) exemplified as the colorant described above may be surface-treated with a surface treatment agent. As the surface treatment, an appropriate treatment can be selected according to the type of core particles, the type of dispersion medium, and the like, and is not limited to a specific treatment.

The adhesive composition disclosed herein may contain a component that contributes to improving the dispersibility of the colorant. Such dispersibility-improving components can be, for example, polymers, oligomers, liquid resins, surfactants (anionic, cationic, nonionic, amphoteric surfactants), and the like. The dispersibility-improving component can be used singly or in combination of two or more. The dispersibility-improving component is preferably dissolved in the pressure-sensitive adhesive composition. The oligomer is, for example, a low-molecular-weight polymer of a monomer component containing one or more acrylic monomers as exemplified above (for example, Mw is less than about 10×10 ⁴ , preferably less than 5×10 ⁴ acrylic oligomer). The liquid resin is, for example, a tackifying resin having a softening point of about 50° C. or less, more preferably about 40° C. or less (typically a tackifying resin such as a rosin-based, terpene-based, or hydrocarbon-based tackifying resin, such as a hydrogenated rosin methyl ester, etc.). Such a dispersibility-improving component can suppress dispersion unevenness of a coloring agent (for example, a particulate black coloring agent such as carbon black), and thus suppress color unevenness of the pressure-sensitive adhesive layer. Therefore, a pressure-sensitive adhesive layer with better appearance quality can be formed.

The form of addition of the dispersibility-improving component is not particularly limited. It may be supplied into the product at the same timing as the colorant, or before or after the addition of the colorant.

The content of the dispersibility-improving component is not particularly limited, and from the viewpoint of suppressing the influence on the adhesive properties (for example, a decrease in cohesion), the total amount of the adhesive layer is about 20% by weight or less (preferably about 10% by weight or less, more (preferably 7% by weight or less, for example approximately 5% by weight or less). In some embodiments, the content of the dispersibility-enhancing component can be about 10 times or less (preferably about 5 times or less, such as about 3 times or less) by weight of the colorant. On the other hand, from the viewpoint of suitably exhibiting the effect of the dispersibility improving component, the content thereof is about 0.2% by weight or more (typically about 0.5% by weight or more, preferably about 1% by weight) of the entire pressure-sensitive adhesive layer. % or more). In some embodiments, the content of the dispersibility-enhancing component can be about 0.2 times or more (preferably about 0.5 times or more, such as 1 time or more) of the weight of the colorant.

The content of the coloring agent in the adhesive layer (when two or more coloring agents are contained, the total amount of the two or more coloring agents, the total content) is determined in consideration of the desired adherend hiding property, required adhesive properties, etc. and is not limited to any particular range. The content of the colorant in the adhesive layer is, for example, approximately 0.3% by weight or more, suitably approximately 0.5% by weight or more, preferably approximately 1% by weight or more, and more preferably approximately 1.5% by weight. % or more, more preferably about 2% by weight or more. In some embodiments, the content of the colorant in the pressure-sensitive adhesive layer is suitably about 3% by weight or more, preferably about 5% by weight or more, more preferably about 7% by weight or more, and about 8% by weight. or more. The content of the colorant in the adhesive layer can be about 30% by weight or less, and about 20% by weight, from the viewpoint of compatibility with the adhesive component and maintenance of adhesive properties such as adhesive strength and impact resistance. % or less, preferably about 15 wt % or less, more preferably about 10 wt % or less, and may be about 8 wt % or less.

The content of the colorant in the pressure-sensitive adhesive layer (when two or more colorants are included, the total amount of the two or more, total content) can also be specified based on the relative relationship with the amount of the base polymer. The content of the colorant is, for example, about 0.3 parts by weight or more, and about 0.5 parts by weight, with respect to 100 parts by weight of the base polymer (preferably acrylic polymer), from the viewpoint of covering the adherend. The above is suitable, preferably about 1 part by weight or more, more preferably about 1.5 parts by weight or more, even more preferably about 2 parts by weight or more, and may be about 2.5 parts by weight or more. In some embodiments, the content of the colorant is appropriately about 3 parts by weight or more, preferably about 5 parts by weight or more, and more preferably about 8 parts by weight or more with respect to 100 parts by weight of the base polymer. , about 10 parts by weight or more. The content of the colorant is about 30 parts by weight with respect to 100 parts by weight of the base polymer, from the viewpoint of light transmittance, compatibility with the adhesive component, and maintenance of adhesive properties such as adhesive strength and impact resistance. It can be the following, and about 25 parts by weight or less is suitable, preferably about 20 parts by weight or less, more preferably about 15 parts by weight or less, and may be about 12 parts by weight or less, and about 8 parts by weight. parts or less, approximately 6 parts by weight or less, or approximately 4 parts by weight or less.

(Infrared absorber)
The adhesive layer disclosed herein is characterized by containing an infrared absorber. Since the pressure-sensitive adhesive layer contains an infrared absorber, the pressure-sensitive adhesive sheet including the pressure-sensitive adhesive layer can shield infrared rays. As used herein, the term “infrared absorbing agent” refers to a material that absorbs light in the wavelength range of 800-1500 nm more than light absorption in the wavelength range of 380-550 nm. The infrared absorbent may be one or more selected from inorganic materials, organic materials, and organic-inorganic composites. From the viewpoint of durability, inorganic materials and organic-inorganic composites are preferred, and inorganic materials are more preferred.

The infrared absorbent disclosed herein does not contain an infrared absorbent when an appropriate amount (for example, 5 to 18 parts by weight with respect to 100 parts by weight of the base polymer) is contained in a pressure-sensitive adhesive layer having a thickness of 30 μm. is a compound that can lower the light transmittance (infrared transmittance) in the wavelength range of 800 to 1500 nm than the pressure-sensitive adhesive layer of the same composition and thickness, and the reduction rate of the infrared transmittance is in the wavelength range of 380 to It may be a compound that reduces the light transmittance (visible light transmittance) at 550 nm more than the reduction rate. The reduction rate of the infrared transmittance is the ratio of the infrared transmittance T _IR1 of the pressure-sensitive adhesive layer containing the infrared absorber to the infrared transmittance T _IR0 of the pressure-sensitive adhesive layer not containing the infrared absorber: (T _IR0 −T _IR1 )/T _IR0 ; Similarly, the reduction rate of the visible light transmittance is the ratio of the visible light transmittance _TVL1 of the pressure-sensitive adhesive layer containing the infrared absorber to the visible light transmittance _TVLO of the pressure-sensitive adhesive layer not containing the infrared absorber: ( _TVL0 −T _VL1 )/T _VL0 ; As the pressure-sensitive adhesive layer used for the evaluation of the infrared absorbing agent, a pressure-sensitive adhesive layer prepared in the same manner as in Example 1 of Examples described later, except that the infrared absorbing agent is not included, can be used. As the infrared transmittances T _IR0 and T _IR1 , the maximum value of light transmittance with a wavelength of 800 to 1500 nm is used. As the visible light transmittances T _VL0 and T _VL1 , the maximum light transmittance in the wavelength range of 380 to 550 nm is used.

In some preferred embodiments, an inorganic material (inorganic compound) is used as the infrared absorber. For example, a metal compound is preferably used as an infrared absorber. Preferred examples of such metal compounds include metal oxides such as tungsten composite oxides and tin composite oxides, and lanthanum borides. For example, by using at least one metal oxide selected from tungsten composite oxides and tin composite oxides as an infrared absorber, excellent infrared shielding can be achieved without impairing the ability to hide the adherend. can be done. Specifically, by using the above-described infrared absorbing agent, not only the near infrared region (800 to 1100 nm) but also infrared rays in a wavelength region longer than 1100 nm can be sufficiently blocked.

The tungsten composite oxide is not particularly limited, but for example, the general formula MxWOy (wherein M is Cs, Rb, K, Tl, In, Ba, Li, Ca, Sr, Fe, Sn, Al , Cu, and Na, wherein 0.1≦x≦0.5 and 2.2≦y≦3.0). M in the formula preferably contains one or more selected from Cs, Rb, K, and Tl, more preferably Cs and Rb, from the viewpoint of forming a crystal structure with excellent infrared absorption. From the viewpoint of durability, Cs is particularly preferred. From the viewpoint of infrared absorption, x in the formula is preferably in the range of 0.20≦x≦0.50, more preferably in the range of 0.25≦x≦0.40, and 0.25≦x≦0.40. Around 33 is particularly preferred. From the viewpoint of chemical stability, y in the formula is more preferably in the range of 2.45≤y≤3.0. It should be noted that the tungsten composite oxide particles may inevitably be mixed with other components during the manufacturing process or the like.

The crystal structure of the tungsten composite oxide is not particularly limited, and the composite tungsten oxide having any crystal structure can be contained. From the viewpoint of infrared absorption, the tungsten composite oxide preferably has a hexagonal crystal structure.

A specific example of the tungsten composite oxide is a cesium-containing tungsten composite oxide. A specific example of the tin composite oxide is antimony-doped tin oxide. A specific example of lanthanum boride is lanthanum hexaboride. Commercially available products include, for example, product names “YMF-02”, “FMF-3A1” and “KHF-7AH” manufactured by Sumitomo Metal Mining Co., Ltd.

In some other embodiments, organic materials (organic compounds) and organic-inorganic composites can be used as infrared absorbers. Examples of such infrared absorbers include cyanine dyes, phthalocyanine dyes, polymethine dyes, squarylium dyes, porphyrin dyes, metal dithiol complex dyes, and diimmonium dyes. These can be used individually by 1 type or in combination of 2 or more types.

Infrared absorbing agents (for example, metal oxides such as tungsten composite oxides) are preferably used in a particulate form. In such an embodiment, the average dispersed particle size of the infrared absorbing agent is, for example, 800 nm or less, preferably 200 nm or less, more preferably 100 nm or less, from the viewpoint of achieving both infrared absorption and visible light transmission. , more preferably 80 nm or less, particularly preferably 60 nm or less. From the viewpoint of improving infrared absorbability, the average dispersed particle size of the infrared absorbing agent is, for example, 1 nm or more, suitably 10 nm or more, 20 nm or more, or 30 nm or more. The average dispersed particle size of the infrared absorber (for example, a metal oxide such as a tungsten composite oxide) is measured using a particle size distribution/particle size distribution measuring device (for example, Nanotrack particle size distribution measuring device manufactured by Nikkiso Co., Ltd.). can do.

The content of the infrared absorbing agent in the adhesive layer is appropriately set in consideration of the desired infrared shielding, not impairing the hiding property of the adherend, the required adhesive properties, etc., and is within a specific range. is not limited to The content of the infrared absorbent in the pressure-sensitive adhesive layer is, for example, about 0.1% by weight or more, suitably about 0.5% by weight or more, and from the viewpoint of improving the infrared shielding effect, preferably about 1% by weight or more. , more preferably about 3% by weight or more, may be about 5% by weight or more, may be about 8% by weight or more, or may be about 10% by weight or more (eg, more than 10% by weight). The content of the infrared absorber in the adhesive layer can be about 30% by weight or less, and about 25% by weight, from the viewpoint of compatibility with the adhesive component and maintenance of adhesive properties such as adhesive strength and impact resistance. % by weight or less is suitable, preferably about 20% by weight or less, more preferably about 15% by weight or less, may be about 12% by weight or less, may be about 9% by weight or less, and may be about 7% by weight. % by weight or less, or approximately 5% by weight or less.

The content of the infrared absorbing agent in the pressure-sensitive adhesive layer can also be specified by the relative relationship with the amount of the base polymer. From the viewpoint of infrared shielding, the content of the infrared absorbing agent is, for example, approximately 0.1 parts by weight or more, and approximately 0.5 parts by weight or more with respect to 100 parts by weight of the base polymer (preferably acrylic polymer). suitable, preferably about 1 part by weight or more, more preferably about 3 parts by weight or more, even more preferably about 5 parts by weight or more, may be about 8 parts by weight or more, and may be about 10 parts by weight or more. , about 12 parts by weight or more, or about 15 parts by weight or more. The content of the infrared absorber may be 40 parts by weight or less with respect to 100 parts by weight of the base polymer from the viewpoint of compatibility with the adhesive component and maintenance of adhesive properties such as adhesive strength and impact resistance. about 30 parts by weight or less is suitable, preferably about 25 parts by weight or less, more preferably about 20 parts by weight or less, may be about 15 parts by weight or less, or about 12 parts by weight or less, It may be about 8 parts by weight or less.

The total amount of the infrared absorber and the colorant contained in the adhesive layer is not particularly limited, and is, for example, about 1 part by weight or more, and about 3 parts by weight with respect to 100 parts by weight of the base polymer (preferably acrylic polymer). Part by weight or more is suitable, and from the viewpoint of suitably realizing concealment of the adherend and infrared shielding, it is preferably about 5 parts by weight or more, may be about 10 parts by weight or more, and is about 15 parts by weight or more. or about 20 parts by weight or more. In addition, the total amount of the infrared absorber and the colorant can be, for example, 40 parts by weight or less with respect to 100 parts by weight of the base polymer, and from the viewpoint of maintaining good adhesive properties, preferably about 30 parts by weight or less. , more preferably about 25 parts by weight or less, may be about 22 parts by weight or less, may be about 18 parts by weight or less, may be about 14 parts by weight or less, or may be about 10 parts by weight or less.

The ratio of the infrared absorbing agent and the colorant used is appropriately set so as to achieve the desired adherend hiding property and infrared shielding, and is not limited to a specific range. In some embodiments, the weight ratio of the amount C _IRA of the infrared absorbing agent to the amount C _COL of the colorant (C _IRA /C _COL ) is 0.1 or more, suitably 0.5 or more, preferably It may be 0.8 or more, may be 1.0 or more, may be 1.2 or more, or may be 1.5 or more. The larger the weight ratio (C _IRA /C _COL ), the better the effect of adding the infrared absorber. In some embodiments, the weight ratio (C _IRA /C _COL ) is 10 or less, suitably 5 or less, preferably 3 or less, more preferably 2 or less, and 1.5 or less. 1.2 or less, or less than 1. The smaller the weight ratio (C _IRA /C _COL ), the better the effect of adding the colorant.

In the technology disclosed herein, the addition form of the colorant (e.g., black colorant such as carbon black particles, metal oxide) and infrared absorber (e.g., tungsten composite oxide) to the pressure-sensitive adhesive composition is not particularly limited. . For example, the colorant and the infrared absorber can be added to the pressure-sensitive adhesive composition in the form of a dispersion in which the particles are dispersed in a dispersion medium. The dispersion medium constituting the dispersion liquid is not particularly limited, and water (ion-exchanged water, reverse osmosis water, distilled water, etc.), various organic solvents (alcohols such as ethanol and butanol; ketones such as acetone and methyl isobutyl ketone) Ethers such as butyl cellosolve and propylene glycol monomethyl ether acetate; Esters such as ethyl acetate and n-butyl acetate; Aromatic hydrocarbons such as toluene; are mentioned. The dispersion liquid may contain the dispersant described above. By mixing the dispersion into the pressure-sensitive adhesive composition, the pressure-sensitive adhesive composition contains a colorant and an infrared absorber, and may further contain a dispersant.

(tackifying resin)
The adhesive layer in the technology disclosed herein can contain a tackifying resin. Thereby, the peel strength of the adhesive sheet can be increased. Examples of tackifying resins include phenol-based tackifying resins, terpene-based tackifying resins, modified terpene-based tackifying resins, rosin-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. Among them, phenol-based tackifying resins, terpene-based tackifying resins, and modified terpene-based tackifying resins are preferable, and phenol-based tackifying resins (preferably terpene phenolic resins) are more preferable.

Examples of phenolic tackifying resins include terpene phenolic resins, hydrogenated terpene phenolic resins, alkylphenolic resins and rosin phenolic 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.
Rosin phenolic resins are typically rosins or phenol-modified products of the various rosin derivatives described above (including rosin esters, unsaturated fatty acid-modified rosins, and unsaturated fatty acid-modified rosin esters). Examples of rosin phenol resins include rosin phenol resins obtained by a method of adding phenol to rosins or various rosin derivatives described above with an acid catalyst and thermally polymerizing the mixture.

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.

The softening point of the tackifying resin is not particularly limited. From the viewpoint of improving cohesive strength, in some embodiments, a tackifying resin having a softening point (softening temperature) of about 80° C. or higher (preferably about 100° C. or higher, for example, higher than 105° C.) can be preferably employed. In the technology disclosed herein, the total amount of the tackifying resin contained in the adhesive layer is 100% by weight, and more than 50% by weight (more preferably more than 70% by weight, for example, more than 90% by weight) has the above softening point. It can be preferably carried out in a mode in which the tackifying resin has. For example, a phenol-based tackifying resin (terpene phenol resin, etc.) having such a softening point can be preferably used. The tackifying resin may include, for example, a terpene phenolic resin having a softening point of approximately 135° C. or higher (and even approximately 140° C. or higher). 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. Thus, by using a tackifying resin having a relatively low softening point, the dispersibility of the infrared absorber and colorant can be improved. The softening point of the tackifying resin can be measured based on the softening point test method (ring and ball method) specified in JIS K2207.

Some preferred embodiments include embodiments in which the tackifying resin comprises one or more phenolic tackifying resins (typically terpene phenolic resins). The technology disclosed herein can be preferably carried out in a mode in which, for example, about 25% by weight or more (more preferably about 30% by weight or more) of the total amount of tackifying resin is 100% by weight is a terpene phenol resin. Approximately 50% by weight or more of the total amount of tackifying resin may be the terpene phenolic resin, and approximately 80% by weight or more (eg, approximately 90% by weight or more) may be the terpene phenolic resin. Substantially all of the tackifying resin (eg, about 95-100 wt%, or even about 99-100 wt%) may be a terpene phenolic resin.

Although not particularly limited, in some embodiments, the tackifying resin may comprise a tackifying resin having a hydroxyl value greater than 20 mg KOH/g. Among them, a tackifying resin having a hydroxyl value of 30 mgKOH/g or more is preferable. Hereinafter, a tackifying resin having a hydroxyl value of 30 mgKOH/g or more may be referred to as a "high hydroxyl value resin". A tackifying resin containing such a high hydroxyl value resin can realize a pressure-sensitive adhesive layer that has excellent adhesion to adherends and high cohesion. In some embodiments, the tackifying resin may contain a high hydroxyl value resin having a hydroxyl value of 50 mgKOH/g or more (more preferably 70 mgKOH/g or more).
As the value of the hydroxyl value, a value measured by a potentiometric titration method specified in JIS K0070:1992 can be adopted.

As the high hydroxyl value resin, among the various tackifying resins described above, those having a hydroxyl value equal to or higher than a predetermined value can be used. High hydroxyl value resin can be used individually by 1 type or in combination of 2 or more types. For example, as the high hydroxyl value resin, a phenolic tackifying resin having a hydroxyl value of 30 mgKOH/g or more can be preferably employed. In some preferred embodiments, a terpene phenolic resin having a hydroxyl value of at least 30 mgKOH/g is used as the tackifying resin. The terpene phenol resin is convenient because the hydroxyl value can be arbitrarily controlled by the copolymerization ratio of phenol.

The upper limit of the hydroxyl value of the high hydroxyl value resin is not particularly limited. From the viewpoint of compatibility with the base polymer, the hydroxyl value of the high hydroxyl value resin is suitably about 200 mgKOH/g or less, preferably about 180 mgKOH/g or less, more preferably about 160 mgKOH/g or less, and even more preferably about 160 mgKOH/g or less. It is about 140 mgKOH/g or less. The technology disclosed herein can be preferably practiced in a mode in which the tackifying resin comprises a high hydroxyl value resin (eg, a phenolic tackifying resin, preferably a terpene phenolic resin) having a hydroxyl value of 30-160 mgKOH/g. In some embodiments, a high hydroxyl value resin with a hydroxyl value of 30-80 mgKOH/g (eg, 30-65 mgKOH/g) can be preferably employed. In some other embodiments, a high hydroxyl value resin with a hydroxyl value of 70-140 mgKOH/g can be preferably employed.

Although not particularly limited, when using a high hydroxyl value resin, the ratio of the high hydroxyl value resin (for example, terpene phenol resin) to the total tackifying resin contained in the adhesive layer is, for example, about 25% by weight or more. about 30% by weight or more is preferable, and about 50% by weight or more (eg, about 80% by weight or more, typically about 90% by weight or more) is more preferable. Substantially all of the tackifying resin (eg, about 95-100 weight percent, or even about 99-100 weight percent) may be a high hydroxyl value resin.

When the pressure-sensitive adhesive layer contains a tackifying resin, the amount of the tackifying resin to be used is not particularly limited, and can be appropriately set, for example, in the range of about 1 to 100 parts by weight with respect to 100 parts by weight of the base polymer. From the viewpoint of suitably exhibiting the effect of improving the peel strength, the amount of the tackifying resin used relative to 100 parts by weight of the base polymer (for example, an acrylic polymer) is preferably 5 parts by weight or more, and 10 parts by weight or more. , and may be 15 parts by weight or more. From the viewpoint of impact resistance and cohesive strength, the amount of tackifying resin used per 100 parts by weight of the base polymer (for example, an acrylic polymer) is preferably 50 parts by weight or less, and even if it is 40 parts by weight or less. Well, it may be 30 parts by weight or less.

(crosslinking agent)
In the technique disclosed here, the adhesive composition used for forming the adhesive layer may contain a cross-linking agent as needed. 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, isocyanate-based cross-linking agents and epoxy-based cross-linking agents are more preferable, and isocyanate-based cross-linking agents are particularly preferable. . The use of an isocyanate-based cross-linking agent tends to provide better impact resistance than other cross-linking systems while obtaining the cohesive strength of the pressure-sensitive adhesive layer. Further, the use of an isocyanate-based cross-linking agent is advantageous, for example, from the point of view of improving the adhesive strength to an adherend made of a polyester resin such as PET. A crosslinking agent can be used individually by 1 type or in combination of 2 or more types.

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. Commercial products of such polyfunctional isocyanates include "Duranate TPA-100" (trade name) manufactured by Asahi Kasei Chemicals, "Coronate L", "Coronate HL", "Coronate HK" and "Coronate 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 base polymer. From the viewpoint of compatibility between cohesion and adhesion, impact resistance, etc., the amount of the isocyanate cross-linking agent used relative to 100 parts by weight of the base polymer can be, for example, 1.0 parts by weight or more, and 1.5 parts by weight. or more (typically 2.0 parts by weight or more, for example 2.5 parts by weight or more). 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 suitably 10 parts by weight or less, and may be 8 parts by weight or less, relative to 100 parts by weight of the base polymer. , 5 parts by weight or less (for example, 3 parts by weight or less).

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 technique 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 pressure-sensitive adhesive layer in the technology disclosed herein contains the cross-linking agent in the form after the cross-linking reaction, the form before the cross-linking reaction, the form after the cross-linking reaction, the intermediate or composite form thereof, or the like. can contain The cross-linking agent is typically contained in the pressure-sensitive adhesive layer exclusively in the form after the cross-linking reaction.

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 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. 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 base polymer. can be done. 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 0.002 parts by weight or more, and about 0.005 parts by weight per 100 parts by weight of the base polymer. Part or more is preferable, and about 0.008 part by weight or more is 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 0.2 parts by weight or less with respect to 100 parts by weight of the base polymer, and about 0.1 part by weight. parts by weight or less, more preferably less than about 0.05 parts by weight, and even more preferably less than about 0.03 parts by weight (for example, about 0.025 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 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 1/50 or less of the content of the isocyanate cross-linking agent. From the viewpoint of achieving both adhesion and cohesive strength to adherends, the content of the non-isocyanate cross-linking agent is about 1/75 or less of the content of the isocyanate cross-linking agent on a weight basis. It is suitable, and preferably about 1/100 or less (for example, 1/150 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 approximately 1/1000 or more, for example approximately 1/500 or more of the content, and may be 1/250 or more.

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, preferably about 0.005 to 10 parts by weight, more preferably about 0.01 to 5 parts by weight, based on 100 parts by weight of the base polymer (preferably acrylic polymer). can be selected from a range of

(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 base 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 base polymer. It may be less than part.

(Other additives)
In the adhesive composition, if necessary, the field of adhesives such as leveling agents, cross-linking aids, plasticizers, softeners, antistatic agents, anti-aging agents, ultraviolet absorbers, antioxidants, light stabilizers, etc. may contain various additives commonly used in 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.

In view of the above, there is provided herein an adhesive composition that includes one or more of the ingredients that can be included in the adhesive layers disclosed herein. The pressure-sensitive adhesive sheet disclosed herein can be produced by using this pressure-sensitive adhesive composition. The pressure-sensitive adhesive composition contains an infrared absorbing agent and a coloring agent different from the infrared absorbing agent. In addition, it may contain a component (typically a base polymer) that can be contained in the pressure-sensitive adhesive layer described above. The content (% by weight or parts by weight) of each component that can be contained in the pressure-sensitive adhesive layer is the content (% by weight or parts by weight) on a solid basis (also referred to as a non-volatile basis) in the pressure-sensitive adhesive composition. can be paraphrased. Other details of the pressure-sensitive adhesive composition are as described for the pressure-sensitive adhesive layer, so repeated descriptions are omitted.

(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. For a pressure-sensitive adhesive sheet having a structure having a supporting 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 supporting substrate and drying the composition is applied. can be adopted. In addition, a method of applying an adhesive composition to a surface having releasability (release surface) and drying it to form an adhesive layer on the surface and transferring the adhesive layer to a support 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 not particularly limited. From the viewpoint of avoiding the adhesive sheet from becoming excessively thick, 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 pressure-sensitive adhesive layer can be approximately 35 μm or less, for example, approximately 25 μm or less, or approximately 15 μm or less. A pressure-sensitive adhesive layer with a limited thickness can well meet demands for thinning and weight reduction. 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 the thickness to about 1 μm or more, appropriately to set it to about 3 μm or more, and preferably to 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 setting the thickness to a predetermined value or more, it is easy to realize adherend concealment and infrared shielding. In addition, desired adhesive properties (adhesive strength, impact resistance, etc.) can be easily obtained. In a double-sided pressure-sensitive adhesive sheet with a substrate having a first pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer on each side of the substrate, the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer have the same thickness. There may be one, or they may have mutually different thicknesses.

(visible light transmittance)
The pressure-sensitive adhesive layer constituting the pressure-sensitive adhesive sheet disclosed herein preferably has a light transmittance (visible light transmittance) in the wavelength range of 380 to 550 nm limited to a predetermined value or less. Utilizing the limited visible light transmittance of the adhesive layer in this manner, the adhesive sheet can conceal the adherend. The visible light transmittance of the adhesive layer (in other words, the maximum light transmittance in the wavelength range of 380 to 550 nm) is preferably 20% or less, more preferably 15% or less, and still more preferably 10% or less. Yes, it may be 8% or less, or 6% or less. The lower the visible light transmittance, the better the hiding power can be exhibited. The lower limit of the visible light transmittance (in other words, the minimum value of light transmittance in the wavelength range of 380 to 550 nm) is not particularly limited, and may be substantially 0%, that is, the detection limit or less. 01% or more, for example, 0.1% or more, or 1.0% or more. In some embodiments, the visible light transmittance (in other words, the minimum light transmittance in the wavelength range of 380 to 550 nm) may be 2.0% or more, or 3.0% or more, It may be 4.0% or more. By increasing the visible light transmittance, the adherend can be visually recognized through the adhesive sheet for inspection or the like. The visible light transmittance of the pressure-sensitive adhesive layer can be measured by the method described in Examples below.

(Infrared transmittance)
The pressure-sensitive adhesive layer constituting the pressure-sensitive adhesive sheet disclosed herein preferably has a light transmittance (infrared transmittance) in the wavelength range of 800 to 1500 nm limited to a predetermined value or less. Thereby, the pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer can shield infrared rays. For example, according to the adhesive layer, regardless of the material or shape of the adherend, defects caused by the passage of infrared rays, such as a decrease in the operating accuracy of the infrared sensor or malfunction, are caused by the infrared shielding property of the adhesive layer. can be prevented from occurring. The infrared transmittance of the pressure-sensitive adhesive layer (in other words, the maximum light transmittance in the wavelength range of 800 to 1500 nm) is preferably 5.0% or less, more preferably 4.0% or less, still more preferably 3 0% or less, particularly preferably 2.0% or less, may be 1.8% or less, or may be 1.5% or less. The lower limit of the infrared transmittance (in other words, the minimum value of light transmittance in the wavelength range of 800 to 1500 nm) is not particularly limited, and may be substantially 0%, that is, below the detection limit, 0.01% 0.05% or more, 0.1% or more, 0.2% or more, or 0.3% or more. The infrared transmittance of the pressure-sensitive adhesive layer can be measured by the method described in Examples below.

The relative relationship between the visible light transmittance and the infrared transmittance of the pressure-sensitive adhesive layer is not particularly limited, and can be appropriately set so as to achieve both adherend-hiding properties and infrared shielding properties. For example, the difference (T _VL - T _IR ) between the infrared transmittance T _IR [%] and the visible light transmittance T _VL [%] of the adhesive layer is, for example, 15 or less, and may be 10 or less. It may be 5 or less, or 3 or less. The smaller the difference (T _VL −T _IR ), the more excellent the adherend-hiding property tends to be. Further, the difference (T _VL −T _IR ) may be, for example, 0.1 or more, 0.5 or more, 1 or more, 1.5 or more, or 1.8 or more, It may be 2 or more. The larger the difference (T _VL −T _IR ), the better the infrared shielding tends to be. In calculating the difference (T _VL −T _IR ), the maximum value [%] of light transmittance at a wavelength of 800 to 1500 nm is used as the infrared transmittance T _IR , and the visible light transmittance T _VL is: The minimum value [%] of light transmittance in the wavelength range of 380 to 550 nm is used.

<Support base material>
In the embodiment in which the pressure-sensitive adhesive sheet disclosed herein is in the form of a single-sided pressure-sensitive adhesive type or double-sided pressure-sensitive adhesive type pressure-sensitive adhesive sheet with a substrate, the substrate that supports (backs) the pressure-sensitive adhesive layer may be a resin film, paper, cloth, or rubber. Sheets, composites thereof, and the like can be used. Examples of resin films include polyolefin films such as polyethylene (PE), polypropylene (PP), and ethylene/propylene copolymer; polyester film; vinyl chloride resin film; vinyl acetate resin film; polyimide resin film; polyamide resin film; 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.

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 resin film here is typically a non-porous resin sheet, and is a concept distinguished from, for example, nonwoven fabrics and woven fabrics (in other words, a concept excluding nonwoven fabrics and woven fabrics). The resin film may be a non-stretched film, a uniaxially stretched film, or a biaxially stretched film.

As the supporting substrate constituting the pressure-sensitive adhesive sheet with a substrate, one containing a resin film as a base film can be preferably used. The base film is typically an independently shape-maintainable (independent) member. The supporting substrate in the technology disclosed herein can be substantially composed of such a base film. Alternatively, the supporting 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). From the viewpoint of handleability and workability, a polyester film is preferable, and a PET film is particularly preferable among them.

The supporting substrate may be one having transparency or one having opacity. In some embodiments, the supporting substrate (eg, resin film) can contain a colorant. This makes it possible to adjust the light transmittance of the supporting substrate. Adjusting the light transmittance (for example, visible light transmittance) of the supporting substrate can be useful for adjusting the light transmittance of the supporting substrate and further the light transmittance of the pressure-sensitive adhesive sheet containing 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 amount of the colorant used in the supporting substrate (for example, a resin film) is not particularly limited, and the amount can be appropriately adjusted so as to impart desired optical properties.

If necessary, the supporting substrate (for example, resin film) may contain fillers (inorganic fillers, organic fillers, etc.), dispersants (surfactants, etc.), anti-aging agents, antioxidants, and ultraviolet absorbers. , antistatic agents, lubricants, and plasticizers. 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 supporting substrate (for example, resin film) may have a single layer structure, or may have a multilayer structure of two layers, three layers or more. From the viewpoint of shape stability, the supporting 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 producing the supporting 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 supporting 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.

Such a colored layer can typically be formed by coating a base film with a colored layer-forming composition containing a coloring agent and a binder. As the coloring agent, conventionally known pigments and dyes can be used in the same manner as the coloring agent that can be contained in the pressure-sensitive adhesive layer and the resin film. Materials known in the field of paints or printing can be used as the binder without particular limitations. Examples include polyurethane, phenol resin, epoxy resin, urea melamine resin, polymethyl methacrylate, and the like. The composition for forming a colored layer may be, for example, a solvent type, an ultraviolet curable type, a heat curable type, or the like. The formation of the colored layer can be carried out by adopting means conventionally used for forming the colored layer without particular limitation. For example, a method of forming a colored layer (printed layer) by printing such as gravure printing, flexographic printing, and offset printing can be preferably employed.

The colored layer may have a single layer structure consisting entirely of one layer, or may have a multilayer structure including two, three or more sub-colored layers. A colored layer having a multi-layer structure including two or more sub-colored layers can be formed, for example, by repeatedly applying (for example, printing) a composition for forming a colored layer. The colors and blending amounts of the colorants contained in each sub-colored layer may be the same or different. From the viewpoint of preventing the occurrence of pinholes, it is particularly significant that the colored layer for imparting concealment properties has a multi-layered structure.

The thickness of the entire colored layer is suitably about 1 μm to 10 μm, preferably about 1 μm to 7 μm, and can be, for example, about 1 μm to 5 μm. In the colored layer including two or more sub-colored layers, the thickness of each sub-colored layer is preferably about 1 μm to 2 μm.

The thickness of the supporting substrate is not particularly limited. From the viewpoint of avoiding the pressure-sensitive adhesive sheet from becoming excessively thick, the thickness of the supporting substrate can be, for example, about 200 μm or less (eg, about 100 μm or less). The thickness of the supporting 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 purpose and usage mode of the pressure-sensitive adhesive sheet. The lower limit of the thickness of the supporting substrate is not particularly limited. From the standpoint of handleability and workability of the pressure-sensitive adhesive sheet, the thickness of the supporting substrate is suitably about 2 μm or more, preferably about 5 μm or more, for example about 10 μm or more.

The surface of the support 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 supporting substrate and the pressure-sensitive adhesive layer, in other words, the anchoring property of the pressure-sensitive adhesive layer to the supporting substrate.

In addition, when the technology disclosed herein is implemented in the form of a substrate-attached single-sided pressure-sensitive adhesive sheet, the back surface of the supporting substrate may be subjected to release treatment as necessary. For the release treatment, for example, general silicone-based, long-chain alkyl-based, and fluorine-based release agents are typically applied to a thin film of about 0.01 μm to 1 μm (eg, 0.01 μm to 0.1 μm). It can be a treatment to give. By applying such a peeling treatment, an effect such as facilitating unwinding of a roll-shaped adhesive sheet can be obtained.

<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.

<Characteristics of adhesive sheet>
(visible light transmittance)
The adhesive sheet disclosed herein preferably has a light transmittance (visible light transmittance) in the wavelength range of 380 to 550 nm limited to a predetermined value or less. The pressure-sensitive adhesive sheet can conceal the adherend by utilizing the visible light transmittance limited in this way. The visible light transmittance of the adhesive sheet (in other words, the maximum light transmittance in the wavelength range of 380 to 550 nm) is preferably 20% or less, more preferably 15% or less, and still more preferably 10% or less. , 8% or less, or 6% or less. The lower the visible light transmittance, the better the hiding power can be exhibited. The lower limit of the visible light transmittance (in other words, the minimum value of light transmittance in the wavelength range of 380 to 550 nm) is not particularly limited, and may be substantially 0%, that is, the detection limit or less. 01% or more, for example, 0.1% or more, or 1.0% or more. In some embodiments, the visible light transmittance (in other words, the minimum light transmittance in the wavelength range of 380 to 550 nm) may be 2.0% or more, or 3.0% or more, It may be 4.0% or more. By having the above-described visible light transmittance, the adherend can be visually recognized through the adhesive sheet for inspection or the like. The visible light transmittance of the adhesive sheet can be measured by the method described in Examples below.

(Infrared transmittance)
The pressure-sensitive adhesive sheet disclosed herein preferably has a light transmittance (infrared transmittance) in the wavelength range of 800 to 1500 nm limited to a predetermined value or less. Thereby, the adhesive sheet can shield infrared rays. For example, according to the adhesive sheet, regardless of the material or shape of the adherend, the infrared shielding property of the adhesive sheet itself may cause problems caused by the passage of infrared rays, such as a decrease in the operating accuracy of an infrared sensor or a malfunction. occurrence can be prevented. The infrared transmittance of the adhesive sheet (in other words, the maximum light transmittance in the wavelength range of 800 to 1500 nm) is preferably 5.0% or less, more preferably 4.0% or less, and still more preferably 3.0% or less. It is 0% or less, particularly preferably 2.0% or less, and may be 1.8% or less, or 1.5% or less. The lower limit of the infrared transmittance (in other words, the minimum value of light transmittance in the wavelength range of 800 to 1500 nm) is not particularly limited, and may be substantially 0%, that is, below the detection limit, 0.01% 0.05% or more, 0.1% or more, 0.2% or more, or 0.3% or more. The infrared transmittance of the adhesive sheet can be measured by the method described in Examples below.

The relative relationship between the visible light transmittance and the infrared transmittance of the adhesive sheet is not particularly limited, and can be appropriately set so as to achieve both adherend-hiding properties and infrared shielding properties. For example, the difference (T _VL −T _IR ) between the infrared transmittance T _IR [%] and the visible light transmittance T _VL [%] of the adhesive sheet is, for example, 15 or less, and may be 10 or less, or 5 It may be less than or equal to 3 or less. The smaller the difference (T _VL −T _IR ), the more excellent the adherend-hiding property tends to be. Further, the difference (T _VL −T _IR ) may be, for example, 0.1 or more, 0.5 or more, 1 or more, 1.5 or more, or 1.8 or more, It may be 2 or more. The larger the difference (T _VL −T _IR ), the better the infrared shielding tends to be. In calculating the difference (T _VL −T _IR ), the maximum value [%] of light transmittance at a wavelength of 800 to 1500 nm is used as the infrared transmittance T _IR , and the visible light transmittance T _VL is: The minimum value [%] of light transmittance in the wavelength range of 380 to 550 nm is used.

(Adhesive force)
The 180-degree peel strength (adhesive strength) of the adhesive sheet disclosed herein is not limited to a specific range, as it may vary depending on the purpose of use and application site. From the viewpoint of obtaining good adhesion to the adherend, the adhesive strength of the adhesive sheet is, for example, about 1.0 N/25 mm or more, preferably about 5.0 N/25 mm or more, more preferably about 5.0 N/25 mm or more. is about 10 N/25 mm or more, more preferably about 12 N/25 mm or more, and may be about 15 N/25 mm or more. According to the technology disclosed herein, it is possible to realize the above adhesive force while realizing the adherend hiding property and infrared shielding. The upper limit of the adhesive strength is not particularly limited, and may be approximately 50 N/25 mm or less (for example, 30 N/25 mm or less). Specifically, the adhesive strength is the 180-degree peel strength against a stainless steel plate measured according to JIS Z 0237, and more specifically, it can be measured by the method described in Examples below. In the case of a double-sided PSA sheet having adhesive surfaces on both sides, the adhesive force on each surface may be the same or different.

(Shear adhesive strength)
Although not particularly limited, the adhesive sheet disclosed herein preferably exhibits a shear adhesive strength of, for example, 1.0 MPa or more. A pressure-sensitive adhesive sheet exhibiting such shear adhesive strength exhibits strong resistance to a force (that is, a shear force) that tends to shift the adhesive interface, and thus is excellent in holding performance of an adherend. From the viewpoint of exhibiting higher holding performance, the adhesive sheet has a shear adhesive strength of preferably 1.5 MPa or more, more preferably 1.8 MPa or more, and still more preferably 2.0 MPa or more. The upper limit of the shear adhesive strength is not particularly limited, and generally the higher the better. On the other hand, from the viewpoint of facilitating the realization of adherend-hiding property and infrared shielding, in some embodiments, the shear adhesive strength may be, for example, 20 MPa or less, 10 MPa or less, 5 MPa or less, or 3 MPa or less. It's okay. The shear adhesive strength can be measured by the method described in Examples below.

(total thickness)
The total thickness of the pressure-sensitive adhesive sheet disclosed herein (which includes a pressure-sensitive adhesive layer and, in a structure having a supporting substrate, further includes a supporting substrate but does not include a release liner) is not particularly limited. The total thickness of the adhesive sheet can be, for example, approximately 300 μm or less, and from the viewpoint of thinning, approximately 200 μm or less is suitable, and approximately 100 μm or less (for example, approximately 70 μm or less) may be used. In some preferred embodiments, the thickness of the adhesive sheet can be approximately 50 μm or less, such as approximately 35 μm or less. The lower limit of the thickness of the pressure-sensitive adhesive sheet is not particularly limited, but it can be about 1 μm or more, for example, about 3 μm or more is suitable, preferably about 6 μm or more, more preferably about 10 μm or more (e.g., about 15 μm or more). above), more preferably about 20 μm or more. By setting the thickness to a predetermined value or more, it is possible to preferably realize adherend concealment and infrared shielding. A pressure-sensitive adhesive sheet having a thickness equal to or greater than a predetermined value tends to be easy to handle, and to have excellent adhesiveness and impact resistance. In addition, in the substrate-less adhesive sheet, the thickness of the adhesive layer is the total thickness of the adhesive sheet.

<Application>
Since the pressure-sensitive adhesive sheet disclosed herein can conceal an adherend, it is suitable for various applications that require concealment of an adherend by taking advantage of this feature. For example, among portable electronic devices, there are some that require the use of an adhesive sheet to conceal members or the like. The adhesive sheet disclosed herein is preferably used for fixing members of such portable electronic devices.

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. Examples of the electronic devices include personal computers (desktop type, notebook type, tablet type, etc.), televisions, and the like. These may incorporate a display device (display device) such as liquid crystal or organic EL.

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 unit) such as a touch panel display in portable electronic devices. By arranging the pressure-sensitive adhesive sheet disclosed herein on the back surface of the display screen (display section), it is possible to prevent deterioration of the visibility of the display screen regardless of how the portable electronic device is used.

In addition, the adhesive sheet disclosed herein is suitable for portable electronic devices with built-in optical sensors. Various devices such as the above-mentioned portable electronic devices use light rays such as infrared rays, visible rays, and ultraviolet rays for the purpose of operating the devices, sensing nearby objects, sensing ambient brightness (environmental light), data communication, etc. An optical sensor may be provided. Examples of the optical sensor include, but are not limited to, an acceleration sensor, a proximity sensor, a brightness sensor (environmental light sensor), and the like. Such an optical 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. In other words, the optical sensor may include a light emitting element and/or a light receiving element for light in a specific wavelength range among wavelength ranges including ultraviolet light, visible light and infrared light. Since the adhesive sheet disclosed herein does not adversely affect the operating accuracy of the sensor, it can be preferably used as a concealing means or an adhesive means in the above devices.

An electronic device having a built-in infrared sensor can be mentioned as a preferable application target of the pressure-sensitive adhesive sheet disclosed herein. Since the pressure-sensitive adhesive sheet disclosed herein can have excellent infrared blocking properties, it effectively blocks infrared rays when used for the purpose of fixing, protecting, covering, or sealing members and the like in the electronic device. It is possible to reduce the influence on the operating accuracy of the infrared sensor caused by light rays from the outside. Such an electronic device may have a biometrics authentication function employing biometrics authentication technology for authenticating an individual based on biometric information such as fingerprints and veins. Infrared sensors can be used in such personal authentication. Examples of the electronic devices include mobile electronic devices having a biometric authentication function capable of personal authentication using fingerprints or the like, and various biometric authentication devices.

Another suitable example of an electronic device (typically a portable electronic device) incorporating the infrared sensor is a device such as a remote control (remote controller) that operates the main body using the infrared sensor. In such a device, it is undesirable for infrared rays to leak from other than the light-emitting portion directed toward the object. It is particularly significant to prevent leakage to the outside. By using the technology disclosed herein for the above applications, it is possible to prevent the infrared sensor from deteriorating in operational accuracy and from malfunctioning.

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, polyethylene Naphthalate resin, etc.), polyvinyl chloride resin, polyphenylene sulfide resin, polyether ether ketone resin, polyamide resin (so-called aramid resin, etc.), polyarylate resin, polycarbonate resin, liquid crystal polymer, etc. Examples include materials (typically 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 above materials may be materials for members constituting products such as electronic devices. The adhesive sheet disclosed herein can be used by being attached to a member made of the above materials. 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 unit. 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 use in covering at least part of the surface of a member or article having a surface (adhesive sheet attachment surface) formed of a metal material such as aluminum or stainless steel, for example. is. Preferred examples of such adherends include metal members such as stainless steel members and aluminum members. By attaching an adhesive sheet to a region of the surface of the metal member that needs to be hidden, the region of the metal member can be hidden. The pressure-sensitive adhesive sheet may cover the entire surface of the metal member, or may cover a portion of the surface (partial region required to be concealed). The metal member may be, for example, a member constituting a supporting portion 240 of a display device 200 shown in FIG. 3, which will be described later. In a mode where the pressure-sensitive adhesive sheet is a double-sided pressure-sensitive adhesive sheet and different adherends (members or articles) are attached to each surface of the double-sided pressure-sensitive adhesive sheet, one of the adherends is preferably a metal member.

In addition, the adhesive sheet disclosed herein is suitable for use in concealing the surface of a metal member that has undergone processing such as openings. A pressure-sensitive adhesive sheet used for such applications may cover the adherend including a region where the metal member as the adherend is partially absent, thereby concealing the adherend. Therefore, the surface (adhesive surface) of the pressure-sensitive adhesive sheet can have an area where the adherend exists (adherend-bonded area) and an area where the adherend does not exist (non-adhered-object area). In this case, infrared rays can pass through the adhesive sheet and the area where the adherend does not exist, but by using the infrared shielding adhesive sheet disclosed herein, the infrared rays are shielded even in the area where the metal member as the adherend does not exist. It is possible to prevent the optical sensor from malfunctioning or the like.

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. According to the technology disclosed herein, it is possible to perform concealment by the pressure-sensitive adhesive sheet (specifically, concealment of the surface of the other adherend in the case of a double-sided pressure-sensitive adhesive sheet) through the light-transmitting adherend as described above. can. In addition, with the light-transmissive adherend, for example, the light beam from the sensor passes through the adherend and reaches the adhesive sheet, so the advantage of the effect (infrared shielding) of the technology disclosed herein is likely to be obtained. The visible light transmittance of the adherend (member or the like) having light transmittance is, for example, 5% or more, and may be 30% or more. In some aspects, the visible light transmittance of the light-transmitting member or the like is, for example, greater than 50%, preferably 70% or more, more preferably 80% or more, and further preferably 90% or more, It may be 95% or more. 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 visible light transmittance of a predetermined value or more as described above. The visible light transmittance can be measured by the same method as the visible light transmittance of the adhesive sheet.

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). Such a laminate may comprise a metal member and an adhesive sheet covering at least part of the surface of the metal member. The pressure-sensitive adhesive sheet may cover the entire surface of the metal member, or may cover a portion of the surface (partial region required to be concealed). Typically, one surface (adhesive surface) of the adhesive sheet is attached to the metal member. In some aspects, the member to which the pressure-sensitive adhesive sheet is attached may have the light transmittance of the adherend material described above. 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.

FIG. 2 shows a structural example of the laminate. The laminate 50 shown in FIG. 2 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 exemplified above as the adherend material are used. The metal member as the first member 41 is preferably an aluminum member or a stainless steel member, more preferably a stainless steel member. By attaching the pressure-sensitive adhesive sheet 1 disclosed herein to a metal member as the first member 41, the metal member can be satisfactorily concealed. Such a metal member may be, for example, a member constituting a supporting portion 240 of a display device 200 shown in FIG. 3, 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 resin film (more specifically, a PET 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 (light emitting diodes) 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. 3 is an exploded perspective view schematically showing a configuration example of the display device. As shown in FIG. 3 , 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 constituting 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,
An adhesive sheet is attached to the support,
The adhesive sheet has an adhesive layer,
The display device, wherein the pressure-sensitive adhesive layer contains an infrared absorbing agent and a coloring agent different from the infrared absorbing agent.
[2] The display device according to [1] above, which incorporates a photosensor including a light-emitting element and/or a light-receiving element for a light beam in a specific wavelength region among wavelength regions including ultraviolet light, visible light, and infrared light.
[3] The display device according to [1] or [2] above, wherein the infrared absorber is a metal compound, preferably selected from tungsten composite oxides and tin composite oxides.
[4] The display device according to any one of [1] to [3] above, wherein the coloring agent includes a black coloring agent.
[5] The display device according to [4] above, wherein the colorant further contains a metal oxide.
[6] The total amount of the infrared absorbing agent and the colorant contained in the pressure-sensitive adhesive layer is in the range of 5 to 30 parts by weight with respect to 100 parts by weight of the base polymer contained in the pressure-sensitive adhesive layer. [1] The display device according to any one of [5].
[7] The display device according to any one of [1] to [6] above, wherein the pressure-sensitive adhesive layer is an acrylic pressure-sensitive adhesive layer containing an acrylic polymer as a base polymer.
[8] The display device according to any one of [1] to [7] above, wherein the pressure-sensitive adhesive layer has a thickness in the range of 10 to 50 μm.
[9] The display device according to any one of [1] to [8] above, wherein the pressure-sensitive adhesive sheet is a substrate-less double-sided adhesive pressure-sensitive adhesive sheet comprising the pressure-sensitive adhesive layer.
[10] The display device according to any one of [1] to [9] above, wherein the pressure-sensitive adhesive sheet has a 180-degree peel strength against a stainless steel plate measured according to JIS Z 0237 of 10 N/25 mm or more.

[11] A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer containing an infrared absorbing agent and a coloring agent different from the infrared absorbing agent.
[12] The pressure-sensitive adhesive sheet according to [11] above, wherein the infrared absorber is a metal compound, preferably selected from tungsten composite oxides and tin composite oxides.
[13] The pressure-sensitive adhesive sheet of [11] or [12] above, wherein the coloring agent contains a black coloring agent.
[14] The pressure-sensitive adhesive sheet of [13] above, wherein the colorant further contains a metal oxide.
[15] The total amount of the infrared absorbent and the colorant contained in the pressure-sensitive adhesive layer is in the range of 5 to 30 parts by weight with respect to 100 parts by weight of the base polymer contained in the pressure-sensitive adhesive layer. [11] The adhesive sheet according to any one of [14].
[16] The pressure-sensitive adhesive sheet according to any one of [11] to [15] above, wherein the pressure-sensitive adhesive layer is an acrylic pressure-sensitive adhesive layer containing an acrylic polymer as a base polymer.
[17] The pressure-sensitive adhesive sheet according to any one of [11] to [16] above, wherein the thickness of the pressure-sensitive adhesive layer is in the range of 10 to 50 µm.
[18] The pressure-sensitive adhesive sheet according to any one of [11] to [17] above, which is a substrate-less double-sided adhesive pressure-sensitive adhesive sheet comprising the pressure-sensitive adhesive layer.
[19] The pressure-sensitive adhesive sheet according to any one of [11] to [18] above, which has a 180-degree peel strength against a stainless steel plate measured according to JIS Z 0237 of 10 N/25 mm or more.
[20] The pressure-sensitive adhesive sheet according to any one of [11] to [19] above, which is used for fixing a member of a portable electronic device.

[21] A laminate comprising a metal member and an adhesive sheet attached to the surface of the metal member,
The adhesive sheet has an adhesive layer,
The laminate, wherein the pressure-sensitive adhesive layer contains an infrared absorbing agent and a coloring agent different from the infrared absorbing agent.
[22] A laminate comprising a light-transmitting member and an adhesive sheet,
One surface of the pressure-sensitive adhesive sheet is attached to the light-transmitting member,
The adhesive sheet has an adhesive layer,
The laminate, wherein the pressure-sensitive adhesive layer contains an infrared absorbing agent and a coloring agent different from the infrared absorbing agent.
[23] A laminate comprising a metal member (first member), an adhesive sheet, and a light-transmitting member (second member) in this order,
The adhesive sheet has an adhesive layer,
The laminate, wherein the pressure-sensitive adhesive layer contains an infrared absorbing agent and a coloring agent different from the infrared absorbing agent.
[24] The laminate according to [21] or [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 laminate according to any one of [21] to [26] above, wherein the infrared absorber is a metal compound, preferably selected from tungsten composite oxides and tin composite oxides.
[28] The laminate according to any one of [21] to [27] above, wherein the coloring agent contains a black coloring agent.
[29] The laminate according to [28] above, wherein the colorant further contains a metal oxide.
[30] The total amount of the infrared absorbing agent and the colorant contained in the pressure-sensitive adhesive layer is in the range of 5 to 30 parts by weight with respect to 100 parts by weight of the base polymer contained in the pressure-sensitive adhesive layer. [21] The laminate according to any one of [29].
[31] The laminate according to any one of [21] to [30] above, wherein the pressure-sensitive adhesive layer is an acrylic pressure-sensitive adhesive layer containing an acrylic polymer as a base polymer.
[32] The laminate as described in any one of [21] to [31] above, wherein the pressure-sensitive adhesive layer has a thickness in the range of 10 to 50 μm.
[33] The laminate according to any one of [21] to [32] above, wherein the pressure-sensitive adhesive sheet is a substrate-less double-sided adhesive pressure-sensitive adhesive sheet comprising the pressure-sensitive adhesive layer.
[34] The laminate according to any one of [21] to [33] above, wherein the adhesive sheet has a 180-degree peel strength against a stainless steel plate measured according to JIS Z 0237 of 10 N/25 mm or more.
[35] The laminate according to any one of [21] to [34] above, which is used in portable electronic devices.

[36] A pressure-sensitive adhesive composition comprising an infrared absorbing agent and a coloring agent different from the infrared absorbing agent.
[37] The pressure-sensitive adhesive composition of [36] above, wherein the infrared absorber is a metal compound.
[38] The pressure-sensitive adhesive composition according to [36] or [37] above, wherein the infrared absorber is selected from tungsten composite oxides and tin composite oxides.
[39] The pressure-sensitive adhesive composition according to any one of [36] to [38] above, wherein the coloring agent contains a black coloring agent.
[40] The pressure-sensitive adhesive composition of [39] above, wherein the colorant further contains a metal oxide.
[41] The adhesive according to any one of [36] to [40] above, wherein the total amount of the infrared absorbent and the colorant is in the range of 5 to 30 parts by weight with respect to 100 parts by weight of the base polymer. agent composition.
[42] The pressure-sensitive adhesive composition according to any one of [36] to [41] above, which contains an acrylic polymer as the base polymer.

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>
[Visible light transmittance and infrared transmittance]
Visible light transmittance [%] and infrared transmittance [%] of the adhesive layer and adhesive sheet were measured using a commercially available spectrophotometer, respectively, in the thickness direction of the adhesive layer and adhesive sheet peeled from the release liner. It is determined by measuring visible light transmittance (wavelength range 380 to 550 nm) and infrared transmittance (wavelength range 800 to 1500 nm). As the spectrophotometer, a spectrophotometer manufactured by Hitachi (apparatus name “UH4150 type spectrophotometer”) or an equivalent thereof is used.

[180 degree peel strength (adhesive strength)]
Under the measurement environment of 23° C. and 50% RH, a PET film having a thickness of 50 μm is adhered to one side of the double-sided adhesive sheet for backing, and a measurement sample is prepared by cutting it into a size of 25 mm in width and 100 mm in length. do. The adhesive surface of the prepared measurement sample is press-bonded to the surface of a stainless steel plate (SUS304BA plate) in an environment of 23° C. and 50% RH by reciprocating a 2-kg roller once. After leaving it in the same environment for 30 minutes, using a universal tensile compression tester, according to JIS Z 0237: 2000, the peel strength (adhesive strength ) [N/25 mm]. As the universal tension/compression tester, for example, "Tensile/compression tester, TG-1kN" manufactured by Minebea Co., Ltd. or its equivalent is used. In the case of a single-sided pressure-sensitive adhesive sheet, the PET film backing is unnecessary.

[Shear adhesive strength]
A measurement sample is prepared by cutting an adhesive sheet (double-sided adhesive sheet) into a size of 10 mm×10 mm. In an environment of 23° C. and 50% RH, each adhesive surface of the measurement sample is superimposed on the surfaces of two stainless steel plates (SUS304BA plates), and pressed by reciprocating a 2 kg roller once. After leaving it under the same environment for 2 days, the shear adhesive strength [MPa] is measured using a tensile tester under the conditions of a tensile speed of 10 mm/min and a peeling angle of 0 degree. In the case of a single-sided adhesive sheet (single-sided adhesive sheet), the non-adhesive surface of the sheet is fixed to a stainless steel plate with an adhesive or the like, and other than that the measurement is performed in the same manner as described above. As a tensile tester, a universal tension/compression tester (product name “TG-1kN”, manufactured by Minebea Co., Ltd.) can be used.

[Hiding property of adherend]
A stainless steel plate is prepared as an adherend, and a mark (black mark) having a length of 10 mm is made on the surface thereof with a commercially available black oil-based marker (marking pen). An evaluation sample is prepared by attaching an adhesive sheet to the surface of the adherend. In a normal indoor environment, it is evaluated whether or not the black mark on the surface of the adherend can be visually recognized through the adhesive sheet. Evaluation is based on the following two criteria.
O: The black mark cannot be visually recognized.
x: A black mark can be visually recognized.
If the black mark cannot be visually recognized in the above evaluation, it is determined that the adherend can be concealed.

[Infrared shielding]
A pressure-sensitive adhesive sheet is attached to the circuit pattern forming surface of the substrate on which the circuit pattern is formed. The circuit pattern is a pattern of aluminum wiring with a line width of 1 mm. Next, using an infrared microscope, the circuit pattern on the substrate surface is confirmed through the adhesive sheet and evaluated according to the following two criteria. As the infrared microscope, a composite device of a stereoscopic microscope (trade name "SMZ745T", manufactured by Nikon Corporation) and an infrared camera (trade name "MC781P0030", manufactured by Texas Instruments) or an equivalent thereof can be used.
◯: The circuit pattern cannot be recognized by infrared rays.
x: The circuit pattern can be recognized by infrared rays.

<Example 1>
(Preparation of acrylic polymer)
A reaction vessel equipped with a stirrer, a thermometer, a nitrogen gas inlet tube, a reflux condenser and a dropping funnel was charged with 95 parts of n-butyl acrylate (BA) and 5 parts of acrylic acid (AA) as monomer components, and 233 parts of ethyl acetate were charged, and the mixture was stirred for 2 hours while nitrogen gas was introduced. 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 was obtained. Mw of this acrylic polymer was about 70×10 ⁴ .

(Preparation of adhesive composition)
In the acrylic polymer solution, 20 parts of a terpene phenol resin as a tackifying resin, 3 parts of an isocyanate cross-linking agent as a cross-linking agent, and an epoxy cross-linking 0.02 parts of an agent, 3 parts of carbon black particles (manufactured by Toyocolor Co., Ltd., trade name "Multilac A903", average particle size 400 nm) as a coloring agent (black coloring agent), and cesium as an infrared absorber A. 5 parts of tungsten composite oxide fine particles (manufactured by Sumitomo Metal Mining Co., Ltd., product name “YMF-02”, average dispersed particle diameter 50 nm) were added and mixed with stirring to prepare an adhesive composition. As the terpene phenol resin (tackifying resin), trade name "YS Polystar T-115" (manufactured by Yasuhara Chemical Co., Ltd., softening point: about 115°C, hydroxyl value: 30-60 mgKOH/g) was used. As the isocyanate-based cross-linking agent, trade name "Coronate L" (manufactured by Tosoh Corporation, 75% ethyl acetate solution of trimethylolpropane/tolylene diisocyanate trimer adduct) was used. As the epoxy-based cross-linking agent, trade name "TETRAD-C" (manufactured by Mitsubishi Gas Chemical Co., Ltd., 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane) was used.

(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 30 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 30 μm and having both sides protected by the two polyester release liners was obtained.

<Example 2>
To the acrylic polymer solution prepared in Example 1, 20 parts of the tackifying resin, 3 parts of the isocyanate crosslinking agent as a crosslinking agent, and the epoxy 0.02 parts of the system crosslinking agent, 0.5 parts of the carbon black particles as the first coloring agent (black coloring agent), and titanium oxide (TiO ₂ ) particles (product Name "WHITE PASTE R-2228", manufactured by Dainichiseika Kogyo Co., Ltd., average particle size 50 nm) and 10 parts of the above cesium-containing tungsten composite oxide fine particles are added, stirred and mixed to obtain an adhesive according to this example. A composition was prepared. 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 solution prepared in Example 1, 20 parts of the tackifying resin, 3 parts of the isocyanate crosslinking agent as a crosslinking agent, and the epoxy 0.02 parts of the system crosslinking agent, 1.0 parts of the carbon black particles as the first coloring agent (black coloring agent), 10 parts of the titanium oxide particles as the second coloring agent (white coloring agent), and infrared rays 18 parts of antimony-doped tin oxide particles (manufactured by Sumitomo Metal Mining Co., Ltd., product name “FMF-3A1”) were added as an absorbent B, and stirred and mixed to prepare a pressure-sensitive adhesive composition according to this example. 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>
A pressure-sensitive adhesive composition according to this example was prepared in the same manner as in Example 1, except that an infrared absorbent was not used and the content of the carbon black particles was changed to 5 parts with respect to 100 parts of the acrylic polymer. A substrate-less double-sided pressure-sensitive adhesive sheet according to this example was produced using the pressure-sensitive adhesive composition.

<Example 5>
A substrate-less double-sided pressure-sensitive adhesive sheet according to this example was produced in the same manner as in Example 2, except that no infrared absorber was used.

<Examples 6-7>
To the acrylic polymer solution prepared in Example 1, 20 parts of the tackifying resin, 3 parts of the isocyanate crosslinking agent as a crosslinking agent, and the epoxy 0.02 part of a system crosslinking agent and 5 parts (Example 6) or 40 parts (Example 7) of the cesium-containing tungsten composite oxide fine particles were added and stirred to mix to prepare a pressure-sensitive adhesive composition according to each example. did. A substrate-less double-sided pressure-sensitive adhesive sheet according to each example was produced in the same manner as in Example 1, except that the pressure-sensitive adhesive composition was used.

An overview of the adhesive according to each example, the minimum value (Min) and maximum value (Max) of the transmittance (visible light transmittance) [%] in the wavelength range of 380 to 550 nm, the transmittance in the wavelength range of 800 to 1500 nm (infrared Transmittance) [%] minimum value (Min) and maximum value (Max), adhesive strength [N / 25 mm], shear adhesive strength [MPa], adherend hiding property and infrared shielding property Evaluation results are shown in Table 1. show. FIG. 4 shows the light transmittance [%] in the wavelength range of 380 to 1500 nm of the pressure-sensitive adhesive sheet according to each example.

As shown in Table 1, the pressure-sensitive adhesive sheets according to Examples 1 to 3 having a pressure-sensitive adhesive layer containing an infrared absorber and a colorant passed both the evaluation results of the adherend hiding property and the infrared shielding property. rice field. On the other hand, in Examples 4 and 5 in which no infrared absorbing agent was used, the evaluation result of the infrared shielding property was unsatisfactory. In Example 4, in which the black colorant was increased and the visible light transmittance was decreased to 0.3 to 0.6%, the maximum infrared transmittance exceeded 5%. In addition, in Examples 6 and 7 in which no coloring agent was used, the adherend-hiding property was not obtained. In Example 6, in which the amount of the infrared absorbing agent used was small, the evaluation result of the infrared shielding property was unacceptable. In Example 7, in which the amount of the infrared absorbing agent was increased, the infrared shielding property was improved, but the adhesive strength tended to decrease. Admitted.
From the above results, it can be seen that the use of a pressure-sensitive adhesive containing an infrared absorber and a colorant makes it possible to realize a pressure-sensitive adhesive sheet that conceals an adherend and is capable of excellent infrared shielding.

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.

1,230 adhesive sheet 1A adhesive surface, first adhesive surface 1B adhesive surface, second adhesive surface 21 adhesive layer 21A adhesive surface, first adhesive surface 21B adhesive surface, second adhesive surface 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 (15)

A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer containing an infrared absorbing agent and a coloring agent different from the infrared absorbing agent. The pressure-sensitive adhesive sheet according to claim 1, wherein the infrared absorber is a metal compound. The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the infrared absorber is selected from tungsten composite oxides and tin composite oxides. The pressure-sensitive adhesive sheet according to any one of claims 1 to 3, wherein the coloring agent comprises a black coloring agent. 5. The pressure-sensitive adhesive sheet according to claim 4, wherein said coloring agent further contains a metal oxide. Claims 1 to 3, wherein the total amount of the infrared absorbing agent and the colorant contained in the pressure-sensitive adhesive layer is in the range of 5 to 30 parts by weight with respect to 100 parts by weight of the base polymer contained in the pressure-sensitive adhesive layer. 6. The pressure-sensitive adhesive sheet according to any one of 5. The pressure-sensitive adhesive sheet according to any one of claims 1 to 6, wherein the pressure-sensitive adhesive layer is an acrylic pressure-sensitive adhesive layer containing an acrylic polymer as a base polymer. The pressure-sensitive adhesive sheet according to any one of claims 1 to 7, wherein the pressure-sensitive adhesive layer has a thickness in the range of 10 to 50 µm. The pressure-sensitive adhesive sheet according to any one of claims 1 to 8, which is a substrate-less double-sided adhesive pressure-sensitive adhesive sheet comprising the pressure-sensitive adhesive layer. The pressure-sensitive adhesive sheet according to any one of claims 1 to 9, which has a 180-degree peel strength against a stainless steel plate measured according to JIS Z 0237 of 10 N/25 mm or more. The pressure-sensitive adhesive sheet according to any one of claims 1 to 10, 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,
An adhesive sheet is attached to the support,
The adhesive sheet has an adhesive layer,
The display device, wherein the pressure-sensitive adhesive layer contains an infrared absorbing agent and a coloring agent different from the infrared absorbing agent. A laminate comprising a metal member and an adhesive sheet attached to the surface of the metal member,
The adhesive sheet has an adhesive layer,
The laminate, wherein the pressure-sensitive adhesive layer contains an infrared absorbing agent and a coloring agent different from the infrared absorbing agent. A laminate comprising a light-transmitting member and an adhesive sheet,
One surface of the pressure-sensitive adhesive sheet is attached to the light-transmitting member,
The adhesive sheet has an adhesive layer,
The laminate, wherein the pressure-sensitive adhesive layer contains an infrared absorbing agent and a coloring agent different from the infrared absorbing agent. A pressure-sensitive adhesive composition comprising an infrared absorbing agent and a coloring agent different from the infrared absorbing agent.

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