CN117321162A

CN117321162A - Pressure-sensitive adhesive sheet, display device, and laminate

Info

Publication number: CN117321162A
Application number: CN202280035818.XA
Authority: CN
Inventors: 伊神俊辉; 西胁匡崇; 小谷知央
Original assignee: Nitto Denko Corp
Current assignee: Nitto Denko Corp
Priority date: 2021-06-18
Filing date: 2022-06-06
Publication date: 2023-12-29
Also published as: JP2023000825A; WO2022264861A1

Abstract

The invention provides an adhesive sheet which masks an adherend and can block infrared rays. The invention provides an adhesive sheet having an adhesive layer. The transmittance of the adhesive sheet for light rays in the wavelength range of 380nm to 550nm is 20% or less, and the transmittance of the adhesive sheet for light rays in the wavelength range of 800nm to 1500nm is 5% or less.

Description

Pressure-sensitive adhesive sheet, display device, and laminate

Technical Field

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

The present application claims priority from japanese patent application No. 2021-101860 filed at month 18 of 2021, the entire contents of which are incorporated herein by reference.

Background

In general, an adhesive (also referred to as a pressure-sensitive adhesive, hereinafter the same applies) exhibits a soft solid (viscoelastic body) state in a temperature range around room temperature, and has a property of being easily adhered to an adherend by pressure. With such properties, adhesives are widely used for various purposes, for example, for joining, fixing, protecting, etc., members in portable electronic devices such as mobile phones. For example, in a portable electronic device such as a mobile phone, an adhesive sheet having a light blocking adhesive layer is used for the purpose of preventing light leakage from a light source such as a backlight module of a liquid crystal display device, a self-light emitting element such as an organic EL (electroluminescence), and the like. For the purpose of masking an adherend, an adhesive sheet having a predetermined light blocking property may be used. Patent document 1 is an example of a document related to such a technique.

In addition, for the purpose of absorbing and blocking near infrared rays (wavelength 800nm to 1100 nm) emitted from a plasma display, an adhesive containing composite tungsten oxide fine particles represented by the general formula MxWyOz, and a highly transparent adhesive film using the adhesive are known. Patent documents 2 to 4 are cited as documents related to such a technique.

Prior art literature

Patent literature

Patent document 1: japanese patent application laid-open No. 2002-235053

Patent document 2: japanese patent application laid-open No. 2018-9053

Patent document 3: japanese patent application laid-open No. 2011-65146

Patent document 4: international publication No. 2009/020207

Disclosure of Invention

Problems to be solved by the invention

The light-blocking adhesive sheet achieves the object of masking the adherend, etc., by covering the entire surface of the adherend on the visual recognition side. For example, an adhesive sheet used for the back side of an organic EL panel or the like is visually recognized when the illumination of a display portion falls, and thus, it is required to mask an adherend with good appearance quality. In this application, a pressure-sensitive adhesive sheet having high light blocking property using a black colorant such as carbon black is preferably used.

However, in various devices such as the above-described portable electronic devices, light sensors using light rays such as infrared rays or visible rays or ultraviolet rays are used for the purpose of personal authentication, operation of the devices, sensing of proximity objects, detection of surrounding brightness (ambient light), data communication, and the like. For example, in a biometric authentication technique for authenticating an individual based on biometric information such as a fingerprint and a vein, an infrared sensor may be used. In such a device, infrared rays from the outside become noise, which may reduce the operation accuracy of the sensor. In a device such as a remote controller (remote control) that operates a main body using an infrared sensor, it is not desirable that infrared light leak from outside a light emitting portion facing an object.

As described above, in a device having an infrared sensor, a light blocking adhesive sheet used by being stuck to an infrared blocking material (adherend) such as metal is not required to have infrared blocking properties, since the adherend can block infrared rays. In addition, since the light blocking adhesive sheet can block visible light by using a black coloring agent or the like to block infrared rays, it is not necessary to use an additional infrared blocking means. However, for example, in a portable electronic device or the like, a member masked by an adhesive sheet may be processed in order to impart a new function or the like, and in an adhesive sheet attached to such a member, a use mode is assumed in which the surface of an adherend is covered with an area including a part where the adherend member is not present, such as a processed part, to mask the adherend. In such a use mode, even in the case of an adhesive sheet capable of sufficiently blocking visible light, when the infrared ray blocking property is insufficient, infrared rays can pass through the adhesive sheet and the region where no adherend is present, and thus there is a possibility that malfunction of the optical sensor or the like may occur due to the infrared rays. For example, a light blocking adhesive sheet using a conventional black colorant such as carbon black can block infrared rays in the near infrared region (800 nm to 1100 nm), but has a tendency to lower infrared ray blocking properties in a wavelength region longer than 1100nm, and does not necessarily have sufficient infrared ray blocking properties. In addition, in the new use mode described above, a higher infrared ray blocking property than the conventional light blocking adhesive sheet may be required. It is practically useful to provide an adhesive sheet having sufficient infrared ray blocking properties in addition to the masking properties of an adherend, so that infrared rays can be blocked without being limited by the material and shape of the adherend.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an adhesive sheet capable of masking an adherend and blocking infrared rays. A related other object is to provide a display device and a laminate having the above adhesive sheet.

Means for solving the problems

According to the present specification, an adhesive sheet having an adhesive layer is provided. The transmittance of the adhesive sheet for light rays in the wavelength range of 380nm to 550nm is 20% or less, and the transmittance of the adhesive sheet for light rays in the wavelength range of 800nm to 1500nm is 5% or less. According to the above configuration, since the transmittance of light in the wavelength range of 380nm to 550nm (visible light transmittance) and the transmittance of light in the wavelength range of 800nm to 1500nm (infrared light transmittance) are limited to the predetermined values or less, the adherend can be masked and infrared light can be blocked. According to the pressure-sensitive adhesive sheet, it is possible to prevent occurrence of defects caused by the passage of infrared rays, such as a decrease in the operation accuracy of the infrared sensor and malfunction, without being limited by the material and shape of the adherend.

In some preferred embodiments, the adhesive layer comprises an infrared absorber and a colorant that is different from the infrared absorber. By selecting an appropriate type of infrared absorber and colorant and incorporating an appropriate amount of infrared absorber and colorant into the adhesive, the visible light transmittance can be set to 20% or less and the infrared transmittance can be set to 5% or less. In addition, by using the infrared absorber and the colorant in combination, the infrared transmittance can be effectively reduced as compared with the case of using the infrared absorber alone. As the infrared absorber, a metal compound can be preferably used.

In some preferred embodiments, the adhesive layer contains at least one selected from tungsten composite oxide and tin composite oxide as an infrared ray absorber. By using at least one selected from the group consisting of tungsten composite oxide and tin composite oxide as an infrared absorber, an adhesive sheet satisfying a visible light transmittance of 20% or less and an infrared transmittance of 5% or less can be suitably produced. By using the tungsten composite oxide and/or the tin composite oxide, not only near infrared rays (800 nm to 1100 nm) but also transmittance of infrared rays having a wavelength longer than 1100nm can be effectively reduced.

In some preferred forms, the adhesive layer comprises a black colorant as the colorant. By using a black colorant as the colorant, a reduction in visible light transmittance can be achieved with a small amount of colorant used. In addition, by using a black colorant, the infrared transmittance can be effectively reduced. This is significant in preventing or suppressing a decrease in adhesive properties caused by the inclusion of a colorant or the like.

In some aspects, the adhesive layer further comprises a metal oxide as a colorant. By using a metal oxide as a colorant in addition to a black colorant, light entering the adhesive can be reflected to reduce visible light transmittance.

In some preferred embodiments, the total amount of the infrared absorber and the colorant contained in the 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 adhesive layer. By setting the total amount of the infrared absorber and the colorant to 5 parts by weight to 30 parts by weight relative to 100 parts by weight of the base polymer, a composition satisfying a visible light transmittance of 20% or less and an infrared transmittance of 5% or less while maintaining good adhesive properties can be suitably obtained.

In some preferred embodiments, the adhesive layer is an acrylic adhesive layer comprising an acrylic polymer as a base polymer. In the constitution having the acrylic pressure-sensitive adhesive layer, the technique disclosed herein can be satisfactorily implemented.

In some preferred embodiments, the adhesive layer has a thickness in the range of 10 μm to 50 μm. By setting the thickness of the pressure-sensitive adhesive layer to 10 μm or more, a composition satisfying a visible light transmittance of 20% or less and an infrared transmittance of 5% or less can be obtained appropriately. In addition, the desired adhesive properties tend to be easily achieved. By setting the thickness of the pressure-sensitive adhesive layer to 50 μm or less, the demand for thickness reduction and weight reduction can be satisfied.

Some preferred adhesive sheets are substrate-free double-sided adhesive sheets composed of the adhesive layer. The substrate-less double-sided adhesive sheet can be thinned to the extent that it does not have a substrate, and can contribute to downsizing and space saving of a product to which the double-sided adhesive sheet is applied. In addition, according to the technology disclosed herein, the composition based on the binder can satisfy the visible light transmittance of 20% or less and the infrared light transmittance of 5% or less, independently of the substrate. In addition, according to the base-material-free adhesive sheet, the adhesive layer such as adhesive strength and impact resistance can be maximally used.

The 180-degree peel strength of the pressure-sensitive adhesive sheet disclosed herein to a stainless steel sheet measured in accordance with JIS Z0237 is preferably 10N/25mm or more. According to the technology disclosed herein, an adhesive sheet that satisfies a visible light transmittance of 20% or less and an infrared transmittance of 5% or less and that also has an adhesive force of a predetermined value or more can be realized. According to the adhesive sheet having the above adhesive force, the adherend can be fixed with a higher adhesive force.

The pressure-sensitive adhesive sheet disclosed herein can mask an adherend, and therefore can be satisfactorily used for various applications requiring masking of an adherend by utilizing this feature. For example, it can be preferable to fix a member of a portable electronic device. The above-described portable electronic devices sometimes require masking of components, and it is interesting to apply the adhesive sheet disclosed herein. Further, since the portable electronic device may incorporate an optical sensor such as an infrared sensor, it is particularly advantageous to use the pressure-sensitive adhesive sheet disclosed herein to block infrared rays and to ensure the operation accuracy of the optical sensor. For example, the fixing device is suitable for fixing a member of a portable electronic device having an infrared sensor built therein.

Further, according to the present specification, there is provided a display device including a display portion including a cover member and an organic EL unit, and a support portion. In this display device, an adhesive sheet is attached to the support portion. In addition, the adhesive sheet has an adhesive layer. The adhesive sheet has a transmittance of 20% or less for light in the wavelength range of 380nm to 550nm, and a transmittance of 5% or less for light in the wavelength range of 800nm to 1500 nm. The adhesive sheet disclosed herein can be satisfactorily used as a constituent element (e.g., a member joining element) of a display device as described above.

Further, according to the present specification, there is provided a laminate having a metal member and an adhesive sheet adhered to a surface of the metal member. In the laminate, the adhesive sheet has an adhesive layer. The adhesive sheet has a transmittance of 20% or less for light in the wavelength range of 380nm to 550nm, and a transmittance of 5% or less for light in the wavelength range of 800nm to 1500 nm. According to the above configuration, the adhesive sheet can mask the metal member by covering the metal member. In addition, the metal member may have infrared blocking properties, but in the case where the metal member is subjected to processing such as opening, the adhesive sheet may cover the adherend including a region where the adherend is not locally present to mask the adherend. In this case, the infrared rays can pass through the pressure-sensitive adhesive sheet and the region where the adherend is not present, and thus the above-described defects caused by the infrared rays may occur. According to the laminate, the infrared ray blocking property of the pressure-sensitive adhesive sheet can be utilized to block infrared rays on the entire sheet surface including the region where the metal member is not present.

Further, according to the present specification, there is provided a laminate having an adhesive sheet and a member having light transmittance. In the laminate, one surface of the pressure-sensitive adhesive sheet is adhered to the light-transmitting member. In addition, the adhesive sheet has an adhesive layer. The adhesive sheet has a transmittance of 20% or less for light in the wavelength range of 380nm to 550nm, and a transmittance of 5% or less for light in the wavelength range of 800nm to 1500 nm. According to the above configuration, the infrared ray can pass through the light-transmitting member, but the presence of the adhesive sheet adhered to the light-transmitting member can realize the infrared ray blocking as a whole of the laminate. For example, in the case where the adhesive sheet is a double-sided adhesive sheet, when the adhesive sheet is used by adhering the adhesive surface of the adhesive sheet opposite to the side to which the light-transmitting member is adhered to an adherend, the laminate can mask the adherend and can block the infrared rays that have passed through the light-transmitting member with the adhesive sheet.

Drawings

Fig. 1 is a cross-sectional view schematically showing one configuration example of an adhesive sheet.

Fig. 2 is a cross-sectional view schematically showing an exemplary configuration of the laminate.

Fig. 3 is an exploded perspective view schematically showing a configuration example of the display device.

FIG. 4 is a graph showing transmittance of light in the wavelength range of 380nm to 550nm of the pressure-sensitive adhesive sheet of each example.

Detailed Description

Hereinafter, preferred embodiments of the present invention will be described. It is to be noted that matters necessary for carrying out the present invention other than those specifically mentioned in the present specification may be understood by those skilled in the art based on the teachings of the present invention and technical knowledge at the time of application. The present invention may be implemented based on the disclosure in the present specification and technical knowledge in the art. In the drawings, members and portions that serve the same function may be denoted by the same reference numerals, and repeated description may be omitted or simplified. In order to clearly illustrate the present invention, the embodiments described in the drawings are schematically shown, and do not necessarily accurately represent the dimensions and scale of the adhesive sheet of the present invention actually provided as a product.

In the present specification, the term "adhesive" refers to a material which is in a soft solid (viscoelastic body) state in a temperature range around room temperature as described above and has a property of being easily adhered to an adherend by pressure. The so-called binders are here, for example, "C.A. Dahlquist," Adhesion: fundamental and Practice ", mcLaren&Sons, (1966) P.143", may be generally defined as having a modulus E that satisfies the complex tensile elastic modulus ^* (1Hz)＜10 ⁷ dyne/cm ² Is a material having the above properties (typically, a material having the above properties at 25 ℃).

Constituent example of adhesive sheet

The pressure-sensitive adhesive sheet disclosed herein may be a pressure-sensitive adhesive sheet with a base material having the above-described pressure-sensitive adhesive layer on one side or both sides of a non-releasable base material (supporting base material), or may be a non-base-material pressure-sensitive adhesive sheet having the above-described pressure-sensitive adhesive layer held on a release liner or the like (i.e., a pressure-sensitive adhesive sheet having no non-releasable base material). The term "adhesive sheet" as used herein may include articles called adhesive tapes, adhesive labels, adhesive films, and the like. The pressure-sensitive adhesive sheet disclosed herein may be in the form of a roll or a sheet. Alternatively, the pressure-sensitive adhesive sheet may be further processed into various shapes.

Fig. 1 shows an example of a structure of a double-sided adhesive type base-less adhesive sheet (base-less double-sided adhesive sheet). The pressure-sensitive adhesive sheet 1 shown in fig. 1 has a structure in which both sides 21A and 21B (the pressure-sensitive adhesive surfaces 1A and 1B of the pressure-sensitive adhesive sheet 1 may be respectively) of a base-free pressure-sensitive adhesive layer 21 are protected by release liners 31 and 32 serving as release surfaces on at least the pressure-sensitive adhesive layer side. Alternatively, the pressure-sensitive adhesive sheet may have a structure in which one surface (the pressure-sensitive adhesive surface, the first pressure-sensitive adhesive surface) of the pressure-sensitive adhesive layer without a base material is protected by a release liner having both surfaces as release surfaces, and when the pressure-sensitive adhesive sheet is wound, the other surface (the pressure-sensitive adhesive surface, the second pressure-sensitive adhesive surface) of the pressure-sensitive adhesive layer is brought into contact with the back surface of the release liner, whereby the second pressure-sensitive adhesive surface of the pressure-sensitive adhesive layer is also protected by the release liner. The technology disclosed herein may be preferably implemented in such a substrate-free form from the viewpoint of reducing the thickness of the adhesive sheet. The pressure-sensitive adhesive sheet without a base material is easily thinned, and is advantageous in that the pressure-sensitive adhesive sheet can exhibit adhesive properties such as adhesive strength and impact resistance to the maximum extent.

< Properties of adhesive sheet etc. >)

(visible light transmittance)

One of the characteristics of the pressure-sensitive adhesive sheet disclosed herein is that the pressure-sensitive adhesive sheet has a transmittance (visible light transmittance) of 20% or less for light in the wavelength range of 380nm to 550 nm. Thus, the pressure-sensitive adhesive sheet can mask an adherend. The visible light transmittance of the pressure-sensitive adhesive sheet (in other words, the maximum value of the transmittance of light in the wavelength range of 380nm to 550 nm) is preferably 15% or less, more preferably 10% or less, and may be 8% or less, or may be 6% or less. The lower the visible light transmittance, the more excellent the masking property can be exhibited. The lower limit of the visible light transmittance (in other words, the minimum value of the transmittance of light in the wavelength range of 380nm to 550 nm) is not particularly limited, and may be substantially 0%, that is, not more than the detection limit, and may be 0.01% 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 value of the transmittance of light in the wavelength range of 380nm to 550 nm) may be 2.0% or more, may be 3.0% or more, or may be 4.0% or more. By having the above visible light transmittance, the adherend can be visually recognized and inspected via the adhesive sheet. The visible light transmittance of the pressure-sensitive adhesive sheet can be measured by the method described in examples described later.

(Infrared transmittance)

One of the characteristics of the pressure-sensitive adhesive sheet disclosed herein is that the pressure-sensitive adhesive sheet has a light transmittance (infrared transmittance) of 5% or less in the wavelength range of 800nm to 1500 nm. Thus, the pressure-sensitive adhesive sheet can block infrared rays. For example, according to the above-described adhesion, occurrence of defects caused by the passage of infrared rays, such as a decrease in the operation accuracy of the infrared sensor and malfunction, can be prevented by the infrared blocking property of the adhesive sheet itself, without being limited by the material and shape of the adherend. The infrared transmittance (in other words, the maximum value of the transmittance of light in the wavelength range of 800nm to 1500 nm) of the pressure-sensitive adhesive sheet is preferably 4.0% or less, more preferably 3.0% or less, further 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 the transmittance of light in the wavelength range of 800nm to 1500 nm) is not particularly limited, and may be substantially 0%, that is, not more than the detection limit, not less than 0.01%, not less than 0.05%, not less than 0.1%, not less than 0.2%, or not less than 0.3%. The infrared transmittance of the pressure-sensitive adhesive sheet can be measured by the method described in examples described below.

The relative relationship between the visible light transmittance and the infrared light transmittance of the pressure-sensitive adhesive sheet is not particularly limited, and may be appropriately set so as to achieve a relationship between the adherend masking property and the infrared light blocking property. For example, the infrared transmittance T of the adhesive sheet _IR [％]And visible light transmittance T _VL [％]Difference (T) _VL -T _IR ) For example, 15 or less, 10 or less, 5 or less, or 3 or less. With the above difference (T _VL -T _IR ) The smaller the size, the more excellent the masking property of the adherend tends to be. In addition, the difference (T _VL -T _IR ) For example, the content may be 0.1 or more, 0.5 or more, 1 or more, 1.5 or more, 1.8 or more, or 2 or more. With difference (T) _VL -T _IR ) The larger the infrared ray blocking tends to be more excellent. After calculating the above difference (T _VL -T _IR ) At the time of the above-mentioned infrared transmittance T _IR A maximum value [%of transmittance of light having a wavelength of 800nm to 1500nm can be used]As the visible light transmittance T _VL The minimum value [%of the transmittance of light in the wavelength range of 380nm to 550nm can be used]。

(adhesive force)

The 180-degree peel strength (adhesive force) of the adhesive sheet disclosed herein may vary depending on the purpose of use and the application site, and is therefore not limited to a specific range. The adhesive force of the adhesive sheet is suitably set to, for example, about 1.0N/25mm or more, preferably about 5.0N/25mm or more, more preferably about 10N/25mm or more, still more preferably about 12N/25mm or more, and may be about 15N/25mm or more, from the viewpoint of obtaining good adhesiveness to an adherend. According to the technology disclosed herein, the above-described adhesive force can be achieved while achieving the adherend masking property and the infrared ray blocking. The upper limit of the adhesive force is not particularly limited, and may be about 50N/25mm or less (for example, 30N/25mm or less). The adhesive force is specifically 180-degree peel strength to a stainless steel sheet measured based on JIS Z0237, and more specifically, can be measured by a method described in examples described later. In the case of a double-sided pressure-sensitive adhesive sheet having a pressure-sensitive adhesive surface on both sides, the pressure-sensitive adhesive force may be the same or different.

(shear adhesion)

Although not particularly limited, the adhesive sheet disclosed herein preferably exhibits a shear adhesion force of, for example, 1.0MPa or more. The adhesive sheet exhibiting such shear adhesive force exhibits strong resistance to a force (i.e., shear force) to offset an adhesive interface, and thus is excellent in holding performance of an adherend. From the viewpoint of exhibiting higher holding performance, the shear adhesion force of the pressure-sensitive adhesive sheet is preferably 1.5MPa or more, more preferably 1.8MPa or more, and even more preferably 2.0MPa or more. The upper limit of the shear adhesion force is not particularly limited, and generally, the higher the shear adhesion force, the more preferable. On the other hand, from the viewpoint of easy realization of the adherend masking property and infrared ray blocking, in some embodiments, the shear adhesion force may be, for example, 20MPa or less, 10MPa or less, 5MPa or less, or 3MPa or less. The shear adhesion force can be measured by the method described in examples described below.

(total thickness)

The total thickness of the adhesive sheet disclosed herein (including the adhesive layer, and the support substrate in the composition having the support substrate, but not including the release liner) is not particularly limited. The total thickness of the pressure-sensitive adhesive sheet may be set to, for example, about 300 μm or less, and from the viewpoint of thickness reduction, about 200 μm or less is preferable, and may be about 100 μm or less (for example, about 70 μm or less). In some preferred embodiments, the thickness of the adhesive sheet may be set to about 50 μm or less, for example, may be about 35 μm or less. The lower limit of the thickness of the pressure-sensitive adhesive sheet is not particularly limited, and may be set to about 1 μm or more, for example, about 3 μm or more, preferably about 6 μm or more, more preferably about 10 μm or more (for example, about 15 μm or more), and still more preferably about 20 μm or more. By setting the thickness to a predetermined value or more, the visible light transmittance and the infrared light transmittance of a predetermined value or less can be easily achieved, and further, the adherend masking and the infrared blocking can be satisfactorily achieved. An adhesive sheet having a thickness of a predetermined value or more tends to be excellent in handleability, adhesiveness, and impact resistance. In the case of the base-material-free adhesive sheet, the thickness of the adhesive layer becomes the total thickness of the adhesive sheet.

< adhesive layer >)

(base Polymer)

In the technology disclosed herein, the kind of the adhesive constituting the adhesive layer is not particularly limited. The pressure-sensitive adhesive may be one containing, as the pressure-sensitive adhesive polymer, one or more of various rubbery polymers such as acrylic polymers, rubber-based polymers (natural rubber, synthetic rubber, a mixture thereof, and the like), polyester-based polymers, urethane-based polymers, polyether-based polymers, polysiloxane-based polymers, polyamide-based polymers, and fluorine-containing polymers, which can be used in the field of pressure-sensitive adhesives (hereinafter, also referred to as "base polymers"). From the viewpoints of adhesive performance, cost, and the like, an adhesive containing an acrylic polymer or a rubber-based polymer as a base polymer can be satisfactorily employed. Among them, an adhesive (acrylic adhesive) having an acrylic polymer as a base polymer is preferable. The techniques disclosed herein are preferably implemented using an acrylic adhesive.

Hereinafter, an adhesive sheet having an adhesive layer made of an acrylic adhesive, that is, an acrylic adhesive layer will be mainly described, but the adhesive layer of the adhesive sheet disclosed herein is not intended to be limited to being made of an acrylic adhesive.

The "base polymer" of the adhesive means the main component of the rubbery polymer contained in the adhesive, and no limitation is made thereto except that it is explained. The rubbery polymer is a polymer exhibiting rubber elasticity in a temperature range around room temperature. In the present specification, unless otherwise specified, "main component" means a component having a content of more than 50% by weight.

In addition, the "acrylic polymer" refers to a polymer containing a monomer unit derived from a monomer having at least one (meth) acryloyl group in one molecule as a monomer unit constituting the polymer. Hereinafter, a monomer having at least one (meth) acryloyl group in one molecule is also referred to as an "acrylic monomer". Thus, the acrylic polymer in the present specification is defined as a polymer containing monomer units derived from an acrylic monomer. Typical examples of the acrylic polymer include acrylic polymers having a ratio of acrylic monomer of more than 50% by weight of all monomer components used in the synthesis of the acrylic polymer.

In addition, "(meth) acryl" refers to both acryl and methacryl in general. Similarly, "(meth) acrylate" refers collectively to acrylates and methacrylates, and "(meth) acrylic" refers collectively to acrylic and methacrylic.

(acrylic Polymer)

As the acrylic polymer in the technology disclosed herein, for example, a polymer containing an alkyl (meth) acrylate as a main monomer, and a monomer raw material which may further contain a sub-monomer having copolymerizability with the main monomer is preferable. The main monomer is a component that accounts for more than 50% by weight of the monomer composition of the monomer raw material.

As the alkyl (meth) acrylate, for example, a compound represented by the following formula (1) can be satisfactorily used.

CH ₂ ＝C(R ¹ )COOR ² (1)

Wherein R in the above formula (1) ¹ Is a hydrogen atom or a methyl group. In addition, R ² Is a chain alkyl group having 1 to 20 carbon atoms. Hereinafter, the range of the number of carbon atoms may be referred to as "C _1-20 ". From the viewpoint of storage modulus of the adhesive, R is ² Is C _1-14 (e.g. C _1-10 Typically C _4-8 ) Alkyl (meth) acrylates of chain alkyl groups are suitable as main monomers. From the viewpoint of adhesion properties, it is preferable toR ¹ Is a hydrogen atom and R ² Is C _4-8 Alkyl acrylate of chain alkyl (hereinafter also referred to simply as acrylic acid C) _4-8 Alkyl esters. ) As the main monomer.

As R ² Is C _1-20 Specific examples of the alkyl (meth) acrylate of the chain alkyl group of (a) are not particularly limited, and examples thereof include: methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, tert-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, 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. As preferable examples of the alkyl (meth) acrylate, n-Butyl Acrylate (BA) and 2-ethylhexyl acrylate (2 EHA) may be cited.

The proportion of the alkyl (meth) acrylate in the monomer component constituting the acrylic polymer is typically more than 50% by weight, and for example, may be 70% by weight or more, 85% by weight or more, or 90% by weight or more. The upper limit of the proportion of the alkyl (meth) acrylate is not particularly limited, but is preferably set to 99.5% by weight or less (for example, 99% by weight or less), or may be set to 98% by weight or less (for example, less than 97% by weight) from the viewpoint of enabling the characteristics (for example, cohesive force) based on the auxiliary monomer such as the carboxyl group-containing monomer to be more effectively exhibited. Alternatively, the acrylic polymer may be a polymer obtained by substantially polymerizing only the alkyl (meth) acrylate.

In addition, in the case of using acrylic acid C _4-8 In the case where an alkyl ester is used as the monomer component, acrylic acid C is contained in the alkyl (meth) acrylate contained in the monomer component _4-8 The proportion of the alkyl ester is preferably 70% by weight or more, more preferably 90% by weight or more. Acrylic acid C _4-8 The alkyl esters may be used singly or two or more may be used in combination.

The technology disclosed herein can contain 50% by weight or more of (meth) acrylic acid C in the monomer component constituting the acrylic polymer _1-6 The manner in which the alkyl esters are carried out is satisfactory. In other words, (meth) acrylic acid C in the acrylic polymer _1-6 The polymerization ratio of the alkyl ester is preferably 50% by weight or more. (meth) acrylic acid C _1-6 The proportion of the alkyl ester in the monomer component (in other words, the polymerization ratio) is more preferably more than 50% by weight, still more preferably 60% by weight or more, particularly preferably 70% by weight or more (for example, 80% by weight or more, still more preferably 85% by weight or more). By using a prescribed amount or more of (meth) acrylic acid C _1-6 The alkyl ester (for example, BA) can satisfactorily disperse a colorant such as a black colorant (for example, carbon black) in the adhesive layer, and can satisfactorily maintain the adhesive properties such as the adhesive strength. Para (meth) acrylic acid C _1-6 The upper limit of the proportion of the alkyl ester in the monomer component is not particularly limited, and may be, for example, 99% by weight or less, and 97% by weight or less depending on the ratio of the alkyl ester to other copolymerizable monomers. (meth) acrylic acid C _1-6 The alkyl esters may be used singly or two or more may be used in combination. As (meth) acrylic acid C _1-6 Alkyl esters, preferably acrylic acid C _1-6 Alkyl esters, more preferably acrylic acid C _2-6 Alkyl esters, more preferably acrylic acid C _4-6 Alkyl esters. In other embodiments, (meth) acrylic acid C _1-6 The alkyl esters are preferably acrylic acid C _1-4 Alkyl esters, more preferably acrylic acid C _2-4 Alkyl esters. As (meth) acrylic acid C _1-6 Preferred examples of alkyl esters include BA.

In the case of using BA as the main monomer, the copolymerization ratio of BA in the acrylic polymer is preferably more than 50% by weight, more preferably 70% by weight or more, and still more preferably 90% by weight or more (for example, more than 90% by weight). By copolymerizing with BA as a main monomer, the adhesive easily attains good adhesion to an adherend. By using a predetermined amount or more of BA, for example, a colorant such as a black colorant (e.g., carbon black) can be satisfactorily dispersed in the adhesive layer, and the adhesive properties such as adhesive strength can be satisfactorily maintained. The copolymerization ratio of BA in the acrylic polymer is not particularly limited, and may be, for example, 99% by weight or less, and 97% by weight or less in view of the copolymerization ratio with another copolymerizable monomer.

The acrylic polymer in the technology disclosed herein may be copolymerized with a secondary monomer. Examples of the auxiliary monomer that can introduce a functional group capable of forming a crosslinking base point or can contribute to the improvement of the adhesive strength into the acrylic polymer include: carboxyl group-containing monomers, hydroxyl group (OH group) -containing monomers, anhydride group-containing monomers, amide group-containing monomers, amino group-containing monomers, epoxy group-containing monomers, cyano group-containing monomers, ketone group-containing monomers, monomers having a nitrogen atom-containing ring, alkoxysilyl group-containing monomers, imide group-containing monomers, and the like. The above auxiliary monomers may be used singly or in combination of two or more.

In the case where 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 properly exhibiting the effect caused by the use of the functional group-containing monomer, the content of the functional group-containing monomer in the monomer component can be set to, for example, 0.1% by weight or more, preferably 0.5% by weight or more, and may be set to 1% by weight or more. In terms of the relationship with the main monomer, the content of the functional group-containing monomer in the monomer component is preferably 40 wt% or less, more preferably 20 wt% or less, and may be 10 wt% or less (for example, 5 wt% or less) from the viewpoint of easily obtaining a balance of adhesive properties.

In some preferred acrylic polymers, the monomer components constituting the acrylic polymer may contain a carboxyl group-containing monomer. By containing a carboxyl group-containing monomer in the monomer component, an adhesive sheet exhibiting good adhesive properties (cohesive force, etc.) can be easily obtained. In addition, the adhesion between the pressure-sensitive adhesive layer and the adherend is also advantageously improved. Further, by copolymerizing an appropriate amount of the carboxyl group-containing monomer, a colorant such as a black colorant (e.g., carbon black) can be easily well dispersed in the adhesive layer, and the adhesive property can be satisfactorily maintained.

Examples of the carboxyl group-containing monomer include Acrylic Acid (AA), methacrylic acid (MAA), carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid. Among them, AA and MAA are preferable. The carboxyl group-containing monomer may be used singly or in combination of two or more.

In the method of copolymerizing the carboxyl group-containing monomer in the acrylic polymer, the content of the carboxyl group-containing monomer in the monomer component constituting the acrylic polymer is not particularly limited, and may be set to, for example, 0.2% by weight or more (typically 0.5% by weight or more) of the monomer component, preferably 1% by weight or more, and may be set to 2% by weight or more, or may be set to 3% by weight or more. By setting the content of the carboxyl group-containing monomer to be more than 3% by weight, a more advantageous effect can be exerted. In some embodiments, the content of the carboxyl group-containing monomer may be set to 3.2 wt% or more, may be set to 3.5 wt% or more, may be set to 4 wt% or more, or may be set to 4.5 wt% or more of the monomer component. The upper limit of the content of the carboxyl group-containing monomer is not particularly limited, and may be set to 15% by weight or less, 12% by weight or less, or 10% by weight or less, for example. The technology disclosed herein can be preferably carried out such that the content of the carboxyl group-containing monomer is 7% by weight or less (typically less than 7% by weight, for example 6.8% by weight or less, or 6.0% by weight or less) of the monomer component.

In the case of using a carboxyl group-containing monomer 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 carboxyl group-containing monomer. This can appropriately exhibit the cohesive force of the carboxyl group, the function as a crosslinking point, the dispersibility of the colorant, and the like. The proportion of the carboxyl group-containing monomer in the whole functional group-containing monomer is preferably 30% by weight or more, more preferably 50% by weight or more, still more preferably 70% by weight or more, still more preferably 90% by weight or more, for example, 97% by weight or more, 98% by weight or more, or 99% by weight or more (for example, 99.9% by weight or more), from the viewpoint of better effect of copolymerizing the carboxyl group-containing monomer. The upper limit of the proportion of the carboxyl group-containing monomer in the whole functional group-containing monomer is 100% by weight, and may be 95% by weight or less, for example.

In other embodiments, as the above-mentioned secondary monomer, an acrylic polymer copolymerized with a hydroxyl group-containing monomer may be used. Examples of the hydroxyl group-containing monomer include hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 4-hydroxybutyl (meth) 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 a linear alkyl group having 2 to 4 carbon atoms. The hydroxyl group-containing monomers may be used singly or two or more kinds may be used in combination.

In the case of using a hydroxyl group-containing monomer as the above-mentioned auxiliary monomer, the content thereof is usually set to about 0.001% by weight or more of the total monomer components, and may be about 0.01% by weight or more (typically about 0.02% by weight or more). The content of the hydroxyl group-containing monomer is suitably set to less than 15% by weight, preferably about 8% by weight or less, more preferably about 3% by weight or less (e.g., less than about 1% by weight) based on the total monomer components. In addition, the techniques disclosed herein may be implemented using an adhesive comprising an acrylic polymer that does not copolymerize hydroxyl-containing monomers.

In other embodiments, an acrylic polymer obtained by copolymerizing a monomer having a nitrogen atom may be used as the above-mentioned auxiliary monomer. Preferable examples of the monomer having a nitrogen atom include monomers having a nitrogen atom-containing ring (such as N-vinyl-2-pyrrolidone and N- (meth) acryloylmorpholine). The monomer having a nitrogen atom may be used singly or two or more kinds may be used in combination.

When a monomer having a nitrogen atom (preferably a monomer having a ring having a nitrogen atom) is used as the auxiliary monomer, the content thereof is not particularly limited, and may be, for example, 1% by weight or more, 3% by weight or more, and further 5% by weight or more or 7% by weight or more of the total monomer components. The amount of the monomer having a nitrogen atom to be used is suitably set to, for example, less than 20% by weight, may be set to less than 10% by weight, may be set to less than 3% by weight, or may be set to less than 1% by weight of the total monomer components. The techniques disclosed herein may be implemented using an adhesive comprising an acrylic polymer that is not copolymerized with a monomer having a nitrogen atom.

The monomer component constituting the acrylic polymer may contain other copolymerizable components in addition to the above-mentioned auxiliary monomers for the purpose of improving the cohesive force or the like. Examples of other copolymerizable 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 vinyl toluene; cycloalkyl (meth) acrylates such as cyclohexyl (meth) acrylate, cyclopentyl (meth) acrylate, isobornyl (meth) acrylate, and the like; aromatic ring-containing (meth) acrylates such as aryl (meth) acrylates (e.g., phenyl (meth) acrylate), aryloxyalkyl (meth) acrylates (e.g., phenoxyethyl (meth) acrylate), and aralkyl (meth) acrylates (e.g., benzyl (meth) acrylate); olefin monomers such as ethylene, propylene, isoprene, butadiene, and isobutylene; chlorine-containing monomers such as vinyl chloride and vinylidene chloride; isocyanate group-containing monomers such as 2- (meth) acryloyloxyethyl isocyanate; alkoxy-containing monomers such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate; vinyl ether monomers such as methyl vinyl ether and ethyl vinyl ether; a polyfunctional monomer having 2 or more (for example, 3 or more) polymerizable functional groups (for example, (meth) acryl) in one molecule, such as 1, 6-hexanediol di (meth) acrylate and trimethylolpropane tri (meth) acrylate; etc.

The amount of the other copolymerizable component is not particularly limited, and may be suitably set to 0.05% by weight or more, or may be set to 0.5% by weight or more, from the viewpoint of suitably exhibiting the effect obtained by using the other copolymerizable component. The content of the other copolymerizable component in the monomer component is preferably 20 wt% or less (for example, 5 wt% or less, and further less than 1 wt%) from the viewpoint of easily obtaining a balance of adhesive properties. The techniques disclosed herein may preferably be practiced in such a way that the monomer component is substantially free of other copolymerized components. Here, the fact that the monomer component does not substantially contain other copolymerized components means that at least other copolymerized components are not intentionally used, and it is permissible to unintentionally contain other copolymerized components, for example, about 0.01% by weight or less.

The copolymerization composition of the acrylic polymer is suitably designed so that the glass transition temperature (Tg) of the polymer is about-15℃or lower (for example, about-70℃or higher and-15℃or lower). Here, tg of the acrylic polymer refers to Tg obtained by Fox equation based on the composition of monomer components used in the synthesis of the polymer. The Fox equation is shown below, and is a relation between Tg of the copolymer and glass transition temperature Tgi of a homopolymer obtained by homopolymerizing monomers constituting the copolymer.

1/Tg＝Σ(Wi/Tgi)

In the above Fox formula, tg represents the glass transition temperature (unit: K) of the copolymer, wi represents the weight fraction (copolymerization ratio based on weight) of the monomer i in the copolymer, and Tgi represents the glass transition temperature (unit: K) of the homopolymer of the monomer i.

As the glass transition temperature of the homopolymer used in the calculation of Tg, the values described in the known materials, specifically, "Polymer Handbook" (3 rd edition, john Wiley & Sons, inc., 1989) are used. For the monomers described in this document with various values, the highest value is used. In the case where it is not described in the Polymer Handbook, a value obtained by a measurement method described in Japanese patent application laid-open No. 2007-51271 is used.

Although not particularly limited, the Tg of the acrylic polymer is favorably about-25℃or lower, preferably about-35℃or lower, more preferably about-40℃or lower, from the viewpoints of impact resistance and adhesion to an adherend. In some embodiments, the Tg of the acrylic polymer is, for example, about-70deg.C or higher, may be about-65deg.C or higher, may be about-60deg.C or higher, or may be about-55deg.C or higher from the standpoint of cohesive force. The techniques disclosed herein can be satisfactorily practiced with acrylic polymers having Tg's of about-65deg.C or more and-35deg.C or less (e.g., about-55deg.C or more and-40deg.C or less). The Tg of the acrylic polymer can be adjusted by appropriately changing the monomer composition (i.e., the kind of monomer used for synthesizing the polymer, the amount ratio used).

The method for obtaining the acrylic polymer is not particularly limited, and various polymerization methods known as a synthetic method of an acrylic polymer, such as a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, a suspension polymerization method, and a photopolymerization method, can be suitably employed. For example, a solution polymerization method can be preferably employed. The polymerization temperature in the solution polymerization can be appropriately selected depending on the types of monomers and solvents used, the types of polymerization initiators, and the like, and may be set to, for example, about 20℃to about 170℃and typically about 40℃to about 140 ℃.

The solvent (polymerization solvent) used for the solution polymerization may be appropriately selected from conventionally known organic solvents (toluene, ethyl acetate, etc.). The initiator used for the polymerization may be appropriately selected from conventionally known polymerization initiators (for example, azo-based polymerization initiators such as 2,2' -Azobisisobutyronitrile (AIBN) and peroxide-based initiators) depending on the kind of polymerization method. The amount of the polymerization initiator to be used may be a usual amount, and for example, may be selected from the range of about 0.005 to about 1 part by weight (typically about 0.01 to about 1 part by weight) relative to 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 may be, for example, about 10X 10 ⁴ About 500X 10 ⁴ Is not limited in terms of the range of (a). From the viewpoint of adhesive properties, the Mw of the base polymer is preferably about 30X 10 ⁴ About 200X 10 ⁴ (more preferably about 45X 10) ⁴ About 150X 10 ⁴ Typically about 65 x 10 ⁴ About 130 x 10 ⁴ ) Is not limited in terms of the range of (a). By using a base polymer having a high Mw, better impact resistance tends to be easily obtained by utilizing the cohesive force of the polymer itself. Here, mw refers to a value in terms of standard polystyrene obtained by GPC (gel permeation chromatography). As a GPC apparatus, for example, model name "HLC-8320GPC" (column: TSK gel GMH-H (S), manufactured by Tosoh Co., ltd.) may be used.

(colorant)

The adhesive layers disclosed herein preferably comprise a colorant. The pressure-sensitive adhesive layer contains a colorant, and the pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer can achieve a visible light transmittance of 20% or less, and can satisfactorily mask an adherend. In addition, for example, by using the infrared absorber and the colorant in combination, excellent infrared blocking can be achieved as compared with the case where the infrared absorber is used alone. The colorant is defined as a coloring component not belonging to an infrared absorber described later, and various materials capable of attenuating light traveling in the adhesive layer by absorbing the light and various materials capable of reducing the amount of light entering the adhesive layer can be used. The colorant may be, for example, black, gray, white, red, blue, yellow, green, yellowish green, orange, violet, gold, silver, pearl, or the like. The above-mentioned colorant may be typically contained in the adhesive layer in a state dispersed in the constituent material of the adhesive layer (may be in a dissolved state). As the colorant, conventionally known pigments and dyes can be used. Examples of the pigment include inorganic pigments and organic pigments. The coloring agent may be used singly or in combination of two or more. By using two or more colorants, the adherend masking property can be improved.

The colorant that can be contained in the adhesive layer is not particularly limited, and may be, for example, a component that can absorb and attenuate light traveling in the adhesive layer, and by containing the colorant in the adhesive layer, a component that reduces the transmittance of light rays of the adhesive layer can be used. As such a colorant (hereinafter also referred to as "first colorant"), a black colorant is preferably used in terms of effectively reducing visible light transmittance and effectively adjusting masking property when used in a small amount. In addition, by using a black colorant and an infrared absorber in combination, the infrared transmittance can be effectively reduced. Specific examples of the black colorant include: carbon black, graphite, aniline black, perylene black, cyanine black, titanium black, inorganic pigment hematite, activated carbon, molybdenum disulfide, chromium complex, anthraquinone-based colorants, and the like. The black colorant may be used singly or in combination of two or more.

In some preferred embodiments, the adhesive layer contains carbon black particles as a colorant (first colorant). As the carbon black particles to be used, carbon black particles commonly called carbon black (furnace black, channel black, acetylene black, thermal black, lamp black, pine black, etc.) can be used without particular limitation. Further, as the carbon black particles, surface-modified carbon black particles having a functional group such as a carboxyl group, an amino group, a sulfonic acid group, a silicon-containing group (for example, an alkoxysilyl group or an alkylsilyl group) can be used. Such surface-modified carbon black particles are also called self-dispersing carbon black, and the addition amount of the dispersing agent is not required or can be reduced. The above carbon black particles may be used singly or in combination of two or more.

In view of effectively reducing visible light transmittance and effectively adjusting masking property by using a small amount, a particulate colorant (pigment) can be preferably used. In some preferred embodiments, colorants having an average particle size of about 10nm or more (e.g., about 30nm or more) may be used (e.g., particulate black colorants such as carbon black). The average particle diameter is, for example, about 50nm or more, may be about 100nm or more, or may be about 150nm or more. The upper limit of the average particle diameter of the colorant is not particularly limited, and may be, for example, about 3000nm or less, or about 1000nm or less. The average particle diameter of the colorant is preferably about 500nm or less, more preferably about 300nm or less, still more preferably about 250nm or less, and still more preferably 200nm or less (for example, about 120nm or less, still more preferably about 100nm or less) from the viewpoint of improving the light blocking property.

The average particle diameter of the colorant in the present specification means a volume average particle diameter, specifically, a particle diameter (50% volume average particle diameter; hereinafter, sometimes simply referred to as "D") at 50% of the cumulative value in the particle size distribution measured by a particle size distribution measuring apparatus based on a laser scattering/diffraction method ₅₀ . ). As the measuring device, for example, the product name "Microtrac MT3000II" manufactured by Microtrac Bell corporation or an equivalent thereof may be used.

In the case where the pressure-sensitive adhesive layer contains the first colorant, the content of the first colorant (preferably, black colorant such as carbon black particles) is appropriately set in consideration of the visible light transmittance to be achieved, the masking property of the adherend, the required adhesive property, and the like, and is not limited to a specific range. In addition, the content of the first colorant may be different depending on the kind of the binder, the shape or particle size of the first colorant, compatibility with the binder, and the like. The content of the first colorant in the pressure-sensitive adhesive layer is preferably about 0.01 wt% or more (for example, 0.05 wt% or more), more preferably about 0.1 wt% or more, still more preferably about 0.2 wt% or more, and may be about 0.3 wt% or more, for example, about 0.5 wt% or more, and may be 0.7 wt% or more, from the viewpoint of lowering the visible light transmittance and masking property of the adherend. In some embodiments, the content of the first colorant is about 1 wt% or more (e.g., greater than 1 wt%), preferably about 2 wt% or more, and may be about 2.5 wt% or more, or may be 3 wt% or more. By increasing the amount of the first colorant used, the infrared transmittance can also be effectively reduced. In the case where the pressure-sensitive adhesive layer contains the first colorant or the case where the pressure-sensitive adhesive layer does not contain the first colorant, the content of the first colorant (preferably, black colorant such as carbon black particles) may be set to about 10% by weight or less, preferably about 7% by weight or less, more preferably about 6% by weight or less, still more preferably about 5% by weight or less, still more preferably about 4% by weight or less, and also about 3% by weight or less. In some embodiments, the first colorant may be present in an amount of about 2 wt% or less (typically less than 2 wt%), may be about 1 wt% or less, more preferably about 0.6 wt% or less, and may be about 0.5 wt% or less (e.g., 0.3 wt% or less). By limiting the content of the first colorant, the adhesive properties such as the adhesive strength tend to be easily maintained. According to the technology disclosed herein, even in the configuration in which the amount of the first colorant used is limited as described above, a desired masking property of the adherend can be achieved.

The content of the first colorant (preferably, black colorant such as carbon black particles) can also be determined by the relative relationship with the amount of the base polymer. In some embodiments, the content of the first colorant is preferably 0.05 parts by weight or more, for example, 0.01 parts by weight or more, based on 100 parts by weight of the base polymer (preferably acrylic polymer), and from the viewpoint of the reduction in visible light transmittance and the masking property of the adherend, 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, may be about 0.5 parts by weight or more, or may be 0.8 parts by weight or more. In other embodiments, the first colorant is present in an amount of about 1 part by weight or greater (e.g., greater than 1 part by weight), preferably about 2 parts by weight or greater, and more preferably about 2.5 parts by weight or greater, based on 100 parts by weight of the base polymer. By increasing the amount of the first colorant used, the infrared transmittance can also be effectively reduced. In the case where the pressure-sensitive adhesive layer contains the first colorant or the pressure-sensitive adhesive layer does not contain the first colorant, the content of the first colorant (preferably, black colorant such as carbon black particles) may be set to 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, even more preferably about 4 parts by weight or less, or about 3.5 parts by weight or less, based on 100 parts by weight of the base polymer (preferably, the acrylic polymer). In some embodiments, the first colorant is present in an amount of about 3 parts by weight or less (typically less than 3 parts by weight), about 2 parts by weight or less, about 1.5 parts by weight or less, or about 1 part by weight or less (e.g., 0.6 parts by weight or less) relative to 100 parts by weight of the base polymer. By limiting the content of the first colorant, the adhesive properties such as the adhesive strength tend to be easily maintained.

In other embodiments, the adhesive layer may be implemented to include a second colorant described below (e.g., a metal oxide described below) as a colorant. For example, in a manner in which the adhesive layer contains at least two kinds of colorants, at least one of the plurality of colorants used may be the first colorant described above or the second colorant described below. In the manner in which the adhesive layer contains at least two colorants, the first colorant and the second colorant may be used in combination.

The second colorant that can be used in the technology disclosed herein is not particularly limited, and may be, for example, a component that can reduce the amount of light entering the adhesive layer, or a component that can increase the light reflectance of the adhesive layer by including the second colorant in the adhesive layer. Such a second colorant may be one or two or more selected from inorganic materials (e.g., metals, metal compounds), organic materials, organic-inorganic composites. Specific examples of the second colorant include: titanium oxide (titanium dioxide such as rutile type titanium dioxide or anatase type titanium dioxide), zinc oxide, cerium oxide, aluminum oxide, silicon oxide, zirconium oxide, magnesium oxide, calcium oxide, tin oxide, barium oxide, cesium oxide, yttrium oxide, or other metal oxide; carbonate compounds such as magnesium carbonate, calcium carbonate (light calcium carbonate, heavy calcium carbonate, etc.), barium carbonate, zinc carbonate, etc.; hydroxides such as aluminum hydroxide, calcium hydroxide, magnesium hydroxide, and zinc hydroxide; silicic acid compounds such as aluminum silicate, magnesium silicate, and calcium silicate; barium sulfate, calcium sulfate, barium stearate, zinc oxide, zinc sulfide, talc, clay, kaolin, titanium phosphate, mica, gypsum, white carbon, diatomaceous earth, bentonite, lithopone, zeolite, sericite, hydrated halloysite, and the like; such as inorganic materials, acrylic resins, polystyrene resins, polyurethane resins, amide resins, polycarbonate resins, silicone resins, urea-formaldehyde resins, melamine resins, and the like. These colorants may be colorants known as white colorants. The second colorant may be used singly or in combination of two or more. The second colorant does not contain carbon black particles, and may be defined as a colorant other than carbon black particles. Typically, no light-absorbing black colorant is included in the second colorant.

In some preferred embodiments, the adhesive layer comprises a metal oxide as the second colorant. By using the first colorant (preferably, black colorant) and the metal oxide in combination, the amount of light entering the adhesive layer can be reduced, and light entering the adhesive layer can be absorbed to reduce visible light transmittance and improve masking properties of the adherend. The metal oxide may be selected from the above materials, and can achieve a desired masking property of the adherend. Preferable examples thereof include titanium oxide, zinc oxide, cerium oxide, aluminum oxide, silicon oxide, zirconium oxide, magnesium oxide, and calcium oxide, and among them, titanium oxide, silicon oxide, and zirconium oxide are preferable, and titanium oxide is particularly preferable. The metal oxides may be used singly or two or more kinds may be used in combination.

In the manner in which the second colorant has a particle shape, the average particle diameter of the second colorant (preferably, metal oxide particles) is not particularly limited. Depending on the thickness of the adhesive layer, the kind of adhesive, etc., particles of an appropriate size that can achieve a desired masking property of the adherend may be used. The average particle diameter of the second colorant may be set to, for example, about 1nm or more, and is preferably about 5nm or more. The average particle diameter of the second colorant is preferably about 10nm or more, and may be about 20nm or more, or may be about 30nm or more, from the viewpoints of the effect of containing the second colorant (for example, a decrease in visible light transmittance due to an increase in light reflectance), compatibility, operability, and the like. The upper limit of the average particle diameter is, for example, about 300nm or less, preferably less than 100nm (for example, 90nm or less), more preferably about 70nm or less, and may be about 50nm or less, or about 35nm or less (for example, about 25nm or less), from the viewpoint of the effect of containing the second colorant (for example, improvement of the light reflectance), and the like, from the viewpoint of maintaining the adhesive property.

In the case where the pressure-sensitive adhesive layer contains the second colorant, the content of the second colorant (preferably, metal oxide) in the pressure-sensitive adhesive layer is appropriately set in consideration of the effect of the second colorant (for example, a decrease in visible light transmittance due to an increase in light reflectance) and the required adhesive property, and the like, and is not limited to a specific range. In addition, the content of the second colorant may be different depending on the kind of the binder, the shape or particle size of the second colorant, compatibility with the binder, and the like. The content of the second colorant in the adhesive layer is preferably about 1% by weight or more, more preferably about 3% by weight or more, still more preferably about 5% by weight or more, and still more preferably about 7% by weight or more, from the viewpoint of effectively obtaining the effect of containing the second colorant. In the case where the pressure-sensitive adhesive layer contains the second colorant or the pressure-sensitive adhesive layer does not contain the second colorant, the content of the second colorant in the pressure-sensitive adhesive layer may be set to about 25 wt% or less, preferably about 20 wt% or less, and more preferably about 15 wt% or less, and may be about 12 wt% or less, and may be about 10 wt% or less, and may be about 8 wt% or less, from the viewpoints of compatibility with the pressure-sensitive adhesive component, retention of adhesive force, impact resistance, and other adhesive properties. According to the technology disclosed herein, in the configuration in which the amount of the second colorant used is limited as described above, a desired masking property of the adherend can be achieved.

The amount of the second colorant, preferably a metal oxide, can also be determined by a relative relationship to the amount of the base polymer. The content of the second colorant is suitably about 1 part by weight or more, preferably about 3 parts by weight or more, more preferably about 5 parts by weight or more, still more preferably about 8 parts by weight or more, and also about 10 parts by weight or more, relative to 100 parts by weight of the base polymer (preferably the acrylic polymer). In the case where the pressure-sensitive adhesive layer contains the second colorant or the pressure-sensitive adhesive layer does not contain the second colorant, the content of the second colorant may be set to about 30 parts by weight or less, preferably about 25 parts by weight or less, more preferably about 20 parts by weight or less, even more preferably about 15 parts by weight or less, and may be about 12 parts by weight or less, or about 10 parts by weight or less, based on 100 parts by weight of the base polymer, from the viewpoints of compatibility with the pressure-sensitive adhesive component, retention of adhesive force, impact resistance, and other adhesive properties.

In the manner in which the adhesive layer contains the first colorant and the second colorant, the use ratio of the amount C1 of the first colorant to the amount C2 of the second colorant is appropriately set so that the target visible light transmittance is reduced, the adherend masking property is achieved, and is not limited to a specific range. In some embodiments, the weight ratio (C1/C2) of the amount C1 of the first colorant (preferably, black colorant) to the amount C2 of the second colorant (preferably, metal oxide) may be 0.001 or more, may be 0.005 or more, may be 0.01 or more, may be 0.03 or more, may be 0.05 or more, and may be 0.10 or more. The larger the above weight ratio (C1/C2), the more satisfactory the effect of adding the first colorant is exhibited. In the embodiment in which the first colorant is a black colorant, the light-blocking property of the pressure-sensitive adhesive layer tends to be improved due to its light absorbability, and the infrared transmittance also tends to be reduced. In some embodiments, the weight ratio (C1/C2) is less than 1, for example, 0.50 or less, 0.40 or less (for example, 0.35 or less), preferably 0.30 or less, 0.20 or less, 0.15 or less, 0.12 or less, 0.09 or less, or 0.06 or less (for example, 0.05 or less). The smaller the weight ratio (C1/C2), the more satisfactory the effect of adding the second colorant can be exhibited. In the embodiment in which the second colorant is a metal oxide, the light reflectance of the pressure-sensitive adhesive layer is increased, and masking properties of the adherend tend to be easily obtained.

In the case where the adhesive layer contains the black colorant as the first colorant and/or the metal oxide as the second colorant, the content of the colorant other than the black colorant and the metal oxide is not particularly limited, and may be set to less than 30% by weight, preferably less than 10% by weight, for example, less than 5.0% by weight, and may be set to less than 3.0% by weight (for example, less than 2.0% by weight, further less than 1% by weight). The techniques disclosed herein may be implemented with an adhesive layer that is substantially free of colorants other than black colorants and metal oxides. In the present specification, "substantially free" means that the adhesive layer is not intentionally added, and the content thereof in the adhesive layer may be, for example, 0.3 wt% or less (for example, 0.1 wt% or less, typically 0.01 wt% or less).

As the colorant, a colorant obtained by surface-treating a material (particulate colorant) exemplified as the above colorant with a surface-treating agent can be used from the viewpoint of compatibility with the binder component. The surface treatment is not limited to a specific one, and may be appropriately selected depending on the type of the core particle, the type of the dispersion medium, and the like.

The adhesive compositions disclosed herein may contain ingredients that help to improve the dispersibility of the colorants described above. The dispersibility enhancing component may be, for example, a polymer, an oligomer, a liquid resin, a surfactant (anionic surfactant, cationic surfactant, nonionic surfactant, amphoteric surfactant), or the like. The dispersibility enhancing component may be used singly or in combination of two or more. The dispersibility enhancing component is preferably dissolved in the adhesive composition. The oligomer may be, for example, a low molecular weight polymer (e.g., mw of less than about 10X 10) ⁴ Preferably less than 5 x 10 ⁴ Acrylic oligomer of (a) and (b) a polymer of (c). The liquid resin may be, for example, a tackifying resin having a softening point of about 50 ℃ or less, more preferably about 40 ℃ or less (typically, a tackifying resin such as rosin, terpene, hydrocarbon, etc., for example, hydrogenated rosin methyl ester, etc.). With such a dispersibility-enhancing component, dispersion unevenness of a colorant (for example, a particulate black colorant such as carbon black) can be suppressed, and further, color unevenness of the adhesive layer can be suppressed. Therefore, an adhesive layer with better appearance quality can be formed.

The manner of adding the dispersibility-enhancing component is not particularly limited, and the component may be contained in a liquid containing a colorant (for example, a black colorant such as carbon black particles) before being blended into the adhesive composition, or may be supplied to the adhesive composition at the same timing as the colorant or before and after the colorant is added.

The content of the dispersibility-enhancing component is not particularly limited, and is suitably set to about 20 wt% or less (preferably about 10 wt% or less, more preferably 7 wt% or less, for example, about 5 wt% or less) of the entire pressure-sensitive adhesive layer from the viewpoint of suppressing the influence on the pressure-sensitive adhesive properties (for example, the decrease in the cohesiveness). In some embodiments, the level of the dispersibility enhancing component may be set to about 10 times or less (preferably about 5 times or less, for example about 3 times or less) the weight of the colorant. On the other hand, from the viewpoint of properly exhibiting the effect of the dispersibility-enhancing component, the content thereof is set to about 0.2% by weight or more (typically about 0.5% by weight or more, preferably about 1% by weight or more) of the entire pressure-sensitive adhesive layer. In some embodiments, the content of the dispersibility enhancing component may be set to about 0.2 times or more (preferably about 0.5 times or more, for example 1 time or more) the weight of the colorant.

In the case where the pressure-sensitive adhesive layer contains a colorant, the content of the colorant in the pressure-sensitive adhesive layer (the total amount or the total content of two or more types when two or more types of colorants are contained) is appropriately set in consideration of the target visible light transmittance reduction, the adherend masking property, the required adhesive property, and the like, and is not limited to a specific range. The content of the colorant in the adhesive layer is, for example, about 0.3% by weight or more, preferably about 0.5% by weight or more, more preferably about 1% by weight or more, still more preferably about 1.5% by weight or more, and still more preferably about 2% by weight or more. In some embodiments, the colorant is present in the adhesive layer in an amount of about 3 wt% or more, preferably about 5 wt% or more, more preferably about 7 wt% or more, and also about 8 wt% or more. In the case where the pressure-sensitive adhesive layer contains a colorant or the pressure-sensitive adhesive layer does not contain a colorant, the content of the colorant in the pressure-sensitive adhesive layer may be set to about 30% by weight or less, preferably about 20% by weight or less, more preferably about 15% by weight or less, even more preferably about 10% by weight or less, and may be about 8% by weight or less, from the viewpoints of compatibility with the pressure-sensitive adhesive component, retention of adhesive force, impact resistance, and other adhesive properties.

The content of the colorant in the adhesive layer (the total amount of two or more in the case of containing two or more colorants, the total content) can be determined by the relative relationship with the amount of the base polymer. From the viewpoint of the reduction in visible light transmittance and the masking property of the adherend, the content of the colorant is, for example, about 0.3 parts by weight or more, preferably about 0.5 parts by weight or more, more preferably about 1 part by weight or more, still more preferably about 1.5 parts by weight or more, still more preferably about 2 parts by weight or more, and may be about 2.5 parts by weight or more, relative to 100 parts by weight of the base polymer (preferably the acrylic polymer). In some embodiments, the colorant is present in an amount of about 3 parts by weight or more, preferably about 5 parts by weight or more, more preferably about 8 parts by weight or more, and also about 10 parts by weight or more, relative to 100 parts by weight of the base polymer. In the case where the pressure-sensitive adhesive layer contains a colorant or the pressure-sensitive adhesive layer does not contain a colorant, the content of the colorant may be set to about 30 parts by weight or less, preferably about 25 parts by weight or less, more preferably about 20 parts by weight or less, even more preferably about 15 parts by weight or less, and may be about 12 parts by weight or less, and may be about 8 parts by weight or less, and may be about 6 parts by weight or less, and may be about 4 parts by weight or less, based on 100 parts by weight of the base polymer, from the viewpoints of light transmittance, compatibility with the pressure-sensitive adhesive component, retention of adhesive force, impact resistance, and other adhesive properties.

(Infrared absorbent)

The adhesive layer disclosed herein preferably comprises an infrared absorber. The adhesive sheet having the adhesive layer can reduce the transmittance of infrared rays and satisfactorily block infrared rays by containing the infrared absorber in the adhesive layer. In the present specification, the term "infrared absorber" refers to a material having a light absorption greater in the wavelength range of 800nm to 1500nm than in the wavelength range of 380nm to 550 nm. The infrared absorber may be one or two or more selected from an inorganic material, an organic material, and an organic-inorganic composite. From the viewpoint of durability, the inorganic material and the organic-inorganic composite are preferable, and the inorganic material is more preferable.

The infrared light absorber disclosed herein is a compound capable of reducing the transmittance (infrared light transmittance) of light in the wavelength range of 800nm to 1500nm when an appropriate amount (for example, 5 parts by weight to 18 parts by weight relative to 100 parts by weight of the base polymer) is contained in the pressure-sensitive adhesive layer having a thickness of 30 μm, as compared with the pressure-sensitive adhesive layer having the same composition and the same thickness except that the infrared light absorber is not contained, and may be a compound having a reduction rate of the infrared light transmittance of more than the reduction rate of the transmittance (visible light transmittance) of light in the wavelength range of 380nm to 550 nm. The reduction rate of the infrared transmittance may be determined by the infrared transmittance T of the adhesive layer containing the infrared absorbent _IR1 Infrared transmittance T relative to an adhesive layer containing no infrared absorber _IR0 Ratio of: (T) _IR0 -T _IR1 )/T _IR0 And (5) obtaining. Similarly, the reduction rate of the visible light transmittance may be determined by the visible light transmittance T of the adhesive layer containing the infrared absorbent _VL1 Visible light transmittance T relative to an adhesive layer containing no infrared absorber _VL0 Ratio of: (T) _VL0 -T _VL1 )/T _VL0 And (5) obtaining. As the pressure-sensitive adhesive layer used for the evaluation of the infrared absorbent, a pressure-sensitive adhesive layer produced by the same method as example 1 of the example described below except that the infrared absorbent was not contained can be used. As the above-mentioned infrared transmittance T _IR0 、T _IR1 A maximum value of transmittance of light having a wavelength of 800nm to 1500nm can be used. As the visible light transmittance T _VL0 、T _VL1 A maximum value of transmittance of light in the wavelength range of 380nm to 550nm can be used.

In some preferred forms, an inorganic material (inorganic compound) may be used as the infrared absorber. For example, as the infrared absorber, a metal compound can be preferably used. Preferable examples of the metal compound include, for example: metal oxides such as tungsten composite oxide and tin composite oxide; lanthanum boride, and the like. For example, by using at least one metal oxide selected from the group consisting of tungsten composite oxide and tin composite oxide as an infrared absorber, an adhesive sheet satisfying a visible light transmittance of 20% or less and an infrared light transmittance of 5% or less can be suitably produced, and further, the masking property of an adherend is not impaired, and excellent infrared ray blocking can be achieved. Specifically, by using the above infrared absorber, not only near infrared rays (800 nm to 1100 nm) but also infrared rays in a wavelength region longer than 1100nm can be sufficiently blocked.

The tungsten composite oxide is not particularly limited, and for example, a tungsten composite oxide represented by the general formula MxWOy (where M is one or more elements selected from Cs, rb, K, tl, in, ba, li, ca, sr, fe, sn, al, cu, na, 0.1.ltoreq.x.ltoreq. 0.5,2.2.ltoreq.y.ltoreq.3.0.) can be used. In the formula, M is preferably one or more selected from Cs, rb, K, tl, more preferably Cs and Rb, from the viewpoint of forming a crystal structure excellent in infrared absorptivity. Cs is particularly preferred from the viewpoint of durability. From the viewpoint of infrared absorptivity, x in the formula is preferably in the range of 0.20.ltoreq.x.ltoreq.0.50, more preferably in the range of 0.25.ltoreq.x.ltoreq.0.40, and particularly preferably around 0.33. Further, from the viewpoint of chemical stability, y in the formula is more preferably in the range of 2.45.ltoreq.y.ltoreq.3.0. In the tungsten composite oxide particles, other components may be inevitably mixed in the manufacturing process or the like.

The crystal structure of the tungsten composite oxide is not particularly limited, and may contain composite tungsten oxide having an arbitrary crystal structure. From the viewpoint of infrared absorptivity, the tungsten composite oxide preferably has a hexagonal crystal structure.

Specific examples of the tungsten composite oxide include tungsten composite oxides containing cesium. Specific examples of the tin composite oxide include tin oxide doped with antimony. Specific examples of lanthanum boride include lanthanum hexaboride. Examples of the commercial products include products "YMF-02", "FMF-3A1", "KHF-7AH" manufactured by Sumitomo Metal mining Co.

In other embodiments, an organic material (organic compound), an organic-inorganic composite, or the like may be used as the infrared absorber. Examples of the infrared absorber include: cyanine dye, phthalocyanine dye, polymethine dye, and squaraineSalt pigments, porphyrin pigments, metal dithiol complex pigments, diimmonium pigments, and the like. These may be used singly or in combination of two or more.

The infrared absorber (for example, a metal oxide such as a tungsten composite oxide) may be preferably used in the form of particles. In this embodiment, the average dispersion particle diameter of the infrared absorber is, for example, 800nm or less, preferably 200nm or less, more preferably 100nm or less, still more preferably 80nm or less, and particularly preferably 60nm or less, from the viewpoint of both infrared absorbability and visible light transmittance. The average dispersion particle diameter of the infrared absorbent is, for example, 1nm or more, preferably 10nm or more, and may be 20nm or more, or 30nm or more, from the viewpoint of improving the infrared absorbability. The average dispersed particle size of the infrared absorber (for example, metal oxide such as tungsten composite oxide) can be measured using a particle size distribution/particle size distribution measuring apparatus (for example, nanotrac particle size distribution measuring apparatus manufactured by daily nectar corporation).

In the case where the pressure-sensitive adhesive layer contains an infrared absorber, the content of the infrared absorber in the pressure-sensitive adhesive layer is appropriately set in consideration of achieving the target infrared transmittance reduction, infrared blocking, no deterioration in the masking property of the adherend, the required adhesive property, and the like, and is not limited to a specific range. The content of the infrared absorber in the pressure-sensitive adhesive layer is, for example, about 0.1 wt% or more, preferably about 1 wt% or more, more preferably about 3 wt% or more, and may be about 5 wt% or more, and may be about 8 wt% or more, and may be about 10 wt% or more (for example, more than 10 wt%) from the viewpoint of reducing the infrared transmittance and improving the infrared blocking effect. In the case of the method in which the adhesive layer contains an infrared absorber or the method in which the adhesive layer does not contain an infrared absorber, the content of the infrared absorber in the adhesive layer may be set to about 30% by weight or less, preferably about 25% by weight or less, more preferably about 20% by weight or less, even more preferably about 15% by weight or less, and may be about 12% by weight or less, and may be about 9% by weight or less, and may be about 7% by weight or less, and may be about 5% by weight or less, from the viewpoints of compatibility with the adhesive component, retention of adhesive force, impact resistance, and other adhesive properties.

The content of the infrared absorber in the adhesive layer may be determined according to the relative relation to the amount of the base polymer. From the viewpoint of reduction in infrared transmittance and infrared blocking, the content of the infrared absorber is, for example, about 0.1 part by weight or more, preferably about 0.5 part by weight or more, more preferably about 1 part by weight or more, still more preferably about 3 parts by weight or more, still more preferably about 5 parts by weight or more, and may be about 8 parts by weight or more, and may be about 10 parts by weight or more, and may be about 12 parts by weight or more, and may be about 15 parts by weight or more, relative to 100 parts by weight of the base polymer (preferably the acrylic polymer). In the case of the method in which the adhesive layer contains an infrared absorber or the method in which the adhesive layer does not contain an infrared absorber, the content of the infrared absorber may be set to 40 parts by weight or less, preferably about 30 parts by weight or less, more preferably about 25 parts by weight or less, even more preferably about 20 parts by weight or less, and may be about 15 parts by weight or less, or about 12 parts by weight or less, or about 8 parts by weight or less, based on 100 parts by weight of the base polymer, from the viewpoints of compatibility with the adhesive component, retention of adhesive force, impact resistance, and other adhesive properties.

In the case where the pressure-sensitive adhesive layer contains an infrared absorber and/or a colorant, the total amount of the infrared absorber and the colorant contained in the pressure-sensitive adhesive layer is not particularly limited, and is preferably about 5 parts by weight or more, may be about 10 parts by weight or more, may be about 15 parts by weight or more, or may be about 20 parts by weight or more, based on 100 parts by weight of the base polymer (preferably, an acrylic polymer), for example, about 1 part by weight or more, and about 3 parts by weight or more, from the viewpoint of reducing the visible light transmittance and the infrared transmittance, and appropriately realizing masking and infrared blocking of an adherend. The total amount of the infrared absorber and the colorant may be set to, for example, 40 parts by weight or less, and is preferably about 30 parts by weight or less, more preferably about 25 parts by weight or less, and may be about 22 parts by weight or less, and may be about 18 parts by weight or less, and may be about 14 parts by weight or less, and may be about 10 parts by weight or less, with respect to 100 parts by weight of the base polymer, from the viewpoint of maintaining good adhesive properties.

The use ratio of the infrared absorber and the colorant is appropriately set so as to achieve the target adherend masking property, infrared blocking property, and is not limited to a specific range. In some embodiments, the amount of infrared absorber C _IRA With the amount C of the colorant _COL Weight ratio (C) _IRA /C _COL ) The content is preferably 0.1 or more, more preferably 0.5 or more, and may be 1.0 or more, 1.2 or more, or 1.5 or more. The weight ratio (C) _IRA /C _COL ) The larger the amount, the more satisfactory the effect of adding the infrared absorber is. In addition, in some embodiments, the weight ratio (C _IRA /C _COL ) The content is preferably 10 or less, more preferably 3 or less, still more preferably 2 or less, and may be 1.5 or less, 1.2 or less, or less than 1. The weight ratio (C) _IRA /C _COL ) The smaller the effect of adding the colorant is, the more satisfactorily.

In the technology disclosed herein, the manner of adding the colorant (e.g., black colorant such as carbon black particles, metal oxide) and the infrared absorber (e.g., tungsten composite oxide) to the adhesive composition is not particularly limited. For example, the colorant and the infrared absorber may be added to the 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 examples thereof include: 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, mixed solvents thereof, and aqueous mixed solvents of water and the above organic solvents. The dispersion may contain the dispersant. The dispersion is mixed with an adhesive composition, which contains a colorant, an infrared absorber, and optionally a dispersant.

(tackifying resin)

The adhesive layer in the technology disclosed herein may contain a tackifying resin. This can improve the peel strength of the adhesive sheet. As the tackifying resin, one or two or more kinds of publicly known various tackifying resins selected from the group consisting of phenol tackifying resins, terpene tackifying resins, modified terpene tackifying resins, rosin tackifying resins, hydrocarbon tackifying resins, epoxy tackifying resins, polyamide tackifying resins, elastomer tackifying resins, ketone tackifying resins and the like can be used. Among them, a phenolic tackifying resin, a terpene tackifying resin, and a modified terpene tackifying resin are preferable, and a phenolic tackifying resin (preferably a terpene phenolic resin) is more preferable.

Examples of the phenolic tackifying resins include terpene phenol resins, hydrogenated terpene phenol resins, alkyl phenol resins, and rosin phenol resins.

Terpene phenol resin is a polymer containing terpene residues and phenol residues, and is a concept including both a copolymer of terpenes and a phenolic compound (terpene-phenol copolymer resin) and a resin obtained by phenol-modifying a terpene homopolymer or copolymer (phenol-modified terpene resin). Preferred examples of terpenes constituting such terpene phenol resins include: monoterpenes such as alpha-pinene, beta-pinene, limonene (including d-bodies, l-bodies, and d/l-bodies (terpineol)). The hydrogenated terpene phenol resin is a hydrogenated terpene phenol resin having a structure obtained by hydrogenating such a terpene phenol resin. Sometimes also referred to as hydrogenated terpene phenolic resins.

The alkylphenol resin is a resin (oleophenol resin) obtained from alkylphenol and formaldehyde. Examples of the alkylphenol resin include novolac-type alkylphenol resins and resol-type alkylphenol resins.

Rosin phenol resins are typically phenolic modifications of rosins or of the various rosin derivatives described above, including rosin esters, unsaturated fatty acid modified rosins and unsaturated fatty acid modified rosin esters. Examples of the rosin phenol resin include rosin phenol resins obtained by a method in which phenol is added to rosin or the above-mentioned various rosin derivatives with an acid catalyst and subjected to thermal polymerization.

Examples of terpene tackifying resins include polymers of terpenes (typically monoterpenes) such as α -pinene, β -pinene, d-limonene, l-limonene, terpineol and the like. The terpene may be a homopolymer or a copolymer of two or more terpenes. Examples of the terpene homopolymer include α -pinene polymer, β -pinene polymer, and terpineol polymer. Examples of the modified terpene resin include resins obtained by modifying the terpene resin. Specifically, styrene-modified terpene resins, hydrogenated terpene resins, and the like can be exemplified.

The softening point of the tackifying resin is not particularly limited. From the viewpoint of improving the cohesive force, in some embodiments, a tackifying resin having a softening point (softening temperature) of about 80 ℃ or higher (preferably about 100 ℃ or higher, for example, more than 105 ℃) can be preferably used. The techniques disclosed herein may preferably be implemented in the following manner: the total amount of tackifying resins contained in the adhesive layer is set to 100% by weight, with more than 50% by weight (more preferably more than 70% by weight, for example more than 90% by weight) being tackifying resins having the softening points described above. For example, a phenol tackifying resin (terpene phenol resin or the like) having such a softening point can be preferably used. The tackifying resin may comprise, for example, a terpene phenol resin having a softening point of about 135 ℃ or higher (further about 140 ℃ or higher). The upper limit of the softening point of the tackifying resin is not particularly limited. From the viewpoint of improving the adhesion to an adherend, in some embodiments, a tackifying resin having a softening point of about 200 ℃ or less (more preferably about 150 ℃ or less, for example, less than 130 ℃) can be preferably used. By using the tackifying resin having a relatively low softening point in this way, dispersibility of the infrared absorber and the 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.

As some preferred embodiments, the above-mentioned tackifying resin may include one or more phenolic tackifying resins (typically terpene phenolic resins). The techniques disclosed herein may be preferably implemented, for example, in the following manner: the total amount of tackifying resin is set to 100 wt%, where about 25 wt% or more (more preferably about 30 wt% or more) is terpene phenol resin. The terpene phenol resin may be present in an amount of about 50 wt% or more, or about 80 wt% or more (for example, about 90 wt% or more) of the total amount of the tackifying resin. Substantially all (e.g., from about 95% to about 100% by weight, further from about 99% to about 100% by weight) of the tackifying resin may also be terpene phenolic resin.

Although not particularly limited, in some embodiments, the tackifying resin may contain tackifying resins having hydroxyl numbers greater than 20 mgKOH/g. Of these, a tackifying resin having a hydroxyl value of 30mgKOH/g or more is preferable. Hereinafter, the tackifying resin having a hydroxyl value of 30mgKOH/g or more may be referred to as "high hydroxyl value resin". By using the tackifying resin containing such a high hydroxyl value resin, an adhesive layer having excellent adhesion to an adherend and high cohesive force can be realized. In some embodiments, the tackifying resin may comprise a high hydroxyl value resin having a hydroxyl value of 50mgKOH/g or more (more preferably 70mgKOH/g or more).

As the value of the above-mentioned hydroxyl value, a value according to JIS K0070 can be used: 1992, a value measured by a potentiometric titration method.

As the high hydroxyl value resin, a resin having a hydroxyl value of a predetermined value or more from the above-mentioned various tackifying resins can be used. The high hydroxyl value resin may be used singly or in combination of two or more. For example, as the high hydroxyl value resin, a phenol tackifying resin having a hydroxyl value of 30mgKOH/g or more can be preferably used. In some preferred embodiments, at least a terpene phenol resin having a hydroxyl value of 30mgKOH/g or more is used as the tackifying resin. The terpene-phenol resin can be suitably used 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. The hydroxyl value of the high-hydroxyl-value resin is suitably about 200mgKOH/g or less, preferably about 180mgKOH/g or less, more preferably about 160mgKOH/g or less, and even more preferably about 140mgKOH/g or less, from the viewpoint of compatibility with the base polymer or the like. The technology disclosed herein may be preferably practiced in such a manner that the tackifying resin comprises a high hydroxyl value resin (e.g., a phenolic tackifying resin, preferably a terpene phenolic resin) having a hydroxyl value of from 30mgKOH/g to 160 mgKOH/g. In some embodiments, it may be preferable to use a high hydroxyl value resin having a hydroxyl value of 30mgKOH/g to 80mgKOH/g (e.g., 30mgKOH/g to 65 mgKOH/g). In other embodiments, a high hydroxyl value resin having a hydroxyl value of 70mgKOH/g to 140mgKOH/g may be preferably used.

Although not particularly limited, in the case of using a high-hydroxyl-value resin, the proportion of the high-hydroxyl-value resin (e.g., terpene phenol resin) in the entire tackifying resin contained in the adhesive layer can be set to, for example, about 25% by weight or more, preferably about 30% by weight or more, and more preferably about 50% by weight or more (e.g., about 80% by weight or more, typically about 90% by weight or more). Substantially all (e.g., about 95 wt% to about 100 wt%, and further about 99 wt% to about 100 wt%) of the tackifying resin may also be a high hydroxyl value resin.

In the case where the adhesive layer contains a tackifying resin, the amount of the tackifying resin to be used is not particularly limited, and may be appropriately set in a range of about 1 part by weight to about 100 parts by weight, for example, relative to 100 parts by weight of the base polymer. The amount of the tackifier resin to be used is preferably 5 parts by weight or more, more preferably 10 parts by weight or more, and still more preferably 15 parts by weight or more, based on 100 parts by weight of the base polymer (for example, acrylic polymer), from the viewpoint of suitably exhibiting the effect of improving the peel strength. The amount of the tackifier resin to be used is preferably 50 parts by weight or less based on 100 parts by weight of the base polymer (for example, acrylic polymer) from the viewpoints of impact resistance and cohesive force, and may be 40 parts by weight or less or 30 parts by weight or less.

(crosslinking agent)

In the technology disclosed herein, the adhesive composition used in the formation of the adhesive layer may contain a crosslinking agent as needed. The type of the crosslinking agent is not particularly limited, and may be appropriately selected from conventionally known crosslinking agents. Examples of such a crosslinking agent include: isocyanate-based crosslinking agent, epoxy-based crosslinking agent,Oxazoline-based crosslinking agents, aziridine-based crosslinking agents, melamine-based crosslinking agents, peroxide-based crosslinking agents, urea-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, carbodiimide-based crosslinking agents, hydrazine-based crosslinking agents, amine-based crosslinking agents, silane-based coupling agents, and the like. Among them, isocyanate-based crosslinking agent, epoxy-based crosslinking agent and +_ are preferable>The oxazoline-based crosslinking agent, the aziridine-based crosslinking agent, and the melamine-based crosslinking agent are more preferably isocyanate-based crosslinking agents, and epoxy-based crosslinking agents, and particularly preferably isocyanate-based crosslinking agents. By using the isocyanate-based crosslinking agent, the cohesive force of the adhesive layer can be obtained, and at the same time, impact resistance superior to other crosslinking systems tends to be obtained. The use of the isocyanate-based crosslinking agent is advantageous from the viewpoint of improving the adhesive strength to an adherend made of a polyester resin such as PET, for example. The crosslinking agent may be used singly or in combination of two or more.

As the isocyanate-based crosslinking agent, polyfunctional isocyanates (refer to compounds having an average of two or more isocyanate groups per molecule, including substances having an isocyanurate structure) can be preferably used. The isocyanate-based crosslinking agent may be used singly or in combination of two or more.

Examples of the polyfunctional isocyanate include: aliphatic polyisocyanates, alicyclic polyisocyanates, aromatic polyisocyanates, and the like.

Specific examples of the aliphatic polyisocyanate include: 1, 2-ethylene diisocyanate; butylene diisocyanate such as 1, 2-butylene diisocyanate, 1, 3-butylene diisocyanate, and 1, 4-butylene diisocyanate; hexamethylene diisocyanate such as 1, 2-hexamethylene diisocyanate, 1, 3-hexamethylene diisocyanate, 1, 4-hexamethylene diisocyanate, 1, 5-hexamethylene diisocyanate and the like; 2-methyl-1, 5-pentane diisocyanate, 3-methyl-1, 5-pentane diisocyanate, lysine diisocyanate, and the like.

Specific examples of the alicyclic polyisocyanate include: isophorone diisocyanate; cyclohexyl diisocyanate such as 1, 2-cyclohexyl diisocyanate, 1, 3-cyclohexyl diisocyanate, and 1, 4-cyclohexyl diisocyanate; cyclopentyl diisocyanate such as 1, 2-cyclopentyl diisocyanate and 1, 3-cyclopentyl diisocyanate; hydrogenated xylylene diisocyanate, hydrogenated toluene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated tetramethylxylylene diisocyanate, 4' -dicyclohexylmethane diisocyanate, and the like.

Specific examples of the aromatic polyisocyanate include: 2, 4-toluene diisocyanate, 2, 6-toluene diisocyanate, 4' -diphenylmethane diisocyanate, 2' -diphenylmethane diisocyanate, 4' -diphenyl ether diisocyanate, 2-nitrodiphenyl-4, 4' -diisocyanate, 2' -diphenylpropane-4, 4' -diisocyanate 3,3' -dimethyldiphenylmethane-4, 4' -diisocyanate, 4' -diphenylpropane diisocyanate, isophthalate diisocyanate, p-phenylene diisocyanate, naphthylene 1, 4-diisocyanate, naphthylene 1, 5-diisocyanate, 3' -dimethoxydiphenyl-4, 4' -diisocyanate, xylylene-1, 4-diisocyanate, xylylene-1, 3-diisocyanate, and the like.

As the preferable polyfunctional isocyanate, polyfunctional isocyanates having three or more isocyanate groups on average per molecule can be exemplified. The trifunctional or higher isocyanate may be a polymer (typically a dimer or trimer) of a difunctional or higher isocyanate, a derivative (e.g., an addition reaction product of a polyol and two or more polyfunctional isocyanates), a polymer, or the like. Examples include: dimers of diphenylmethane diisocyanate or trimers of diphenylmethane diisocyanate, isocyanurate bodies of hexamethylene diisocyanate (isocyanurate structure trimer adducts), reaction products of trimethylolpropane and toluene diisocyanate, reaction products of trimethylolpropane and hexamethylene diisocyanate, polymethylene polyphenyl isocyanate, polyether polyisocyanate, polyester polyisocyanate and other polyfunctional isocyanates. Examples of the commercial products of the polyfunctional isocyanate include: trade names "DURANATE TPA-100" manufactured by Asahi chemical Co., ltd., trade name "CORON ATE L" manufactured by Tosoh Co., ltd., and "CORONATE HL" manufactured by Tosoh Co., ltd., and "CORONATE HK" manufactured by Tosoh Co., ltd., and "CORONATE 2096" manufactured by Tosoh Co., ltd., etc.

The amount of the isocyanate-based crosslinking agent used is not particularly limited. For example, the amount of the polymer is set to about 0.5 parts by weight or more based on 100 parts by weight of the base polymer. The amount of the isocyanate-based crosslinking agent used may be, for example, 1.0 part by weight or more, or 1.5 parts by weight or more (typically 2.0 parts by weight or more, for example, 2.5 parts by weight or more) based on 100 parts by weight of the base polymer, from the viewpoint of both the cohesive force and the adhesion, impact resistance, and the like. On the other hand, the amount of the isocyanate-based crosslinking agent used is preferably 10 parts by weight or less based on 100 parts by weight of the base polymer, and may be 8 parts by weight or less or 5 parts by weight or less (for example, 3 parts by weight or less) from the viewpoint of improving the adhesion to an adherend.

In some preferred embodiments, as the crosslinking agent, an isocyanate-based crosslinking agent and at least one crosslinking agent having a different kind of crosslinkable functional group from the isocyanate-based crosslinking agent may be used in combination. According to the technology disclosed herein, excellent cohesive force can be exerted by using a combination of a crosslinking agent other than an isocyanate-based crosslinking agent (that is, a crosslinking agent having a different kind of crosslinkable reactive group from the isocyanate-based crosslinking agent; hereinafter also referred to as "non-isocyanate-based crosslinking agent"). The pressure-sensitive adhesive layer in the technology disclosed herein may contain the crosslinking agent in a form after the crosslinking reaction, a form before the crosslinking reaction, a form in which the crosslinking reaction is partially performed, a form in which the crosslinking reaction is intermediate or composite with the pressure-sensitive adhesive layer, or the like. The above-mentioned crosslinking agent is typically contained in the adhesive layer mainly in a form after the crosslinking reaction.

The type of the non-isocyanate-based crosslinking agent that can be used in combination with the isocyanate-based crosslinking agent is not particularly limited, and can be appropriately selected from the above-mentioned crosslinking agents. The non-isocyanate crosslinking agent may be used singly or in combination of two or more.

In some preferred embodiments, an epoxy-based crosslinking agent may be used as the non-isocyanate-based crosslinking agent. For example, the combination of an isocyanate-based crosslinking agent and an epoxy-based crosslinking agent facilitates both of the cohesiveness and impact resistance. As the epoxy-based crosslinking agent, a compound having two or more epoxy groups in one molecule can be used without particular limitation. Epoxy-based crosslinking agents having three to five epoxy groups in one molecule are preferred. The epoxy-based crosslinking agent may be used singly or in combination of two or more.

Specific examples of the epoxy-based crosslinking agent include, but are not particularly limited to: n, N, N ', N' -tetraglycidyl-m-xylylenediamine, 1, 3-bis (N, N-diglycidyl aminomethyl) cyclohexane, 1, 6-hexanediol diglycidyl ether, polyethylene glycol diglycidyl ether, polyglycidyl ether, and the like. Examples of the commercial products of the epoxy-based crosslinking agent include: trade names "TETRAD-C" and "TETRAD-X" manufactured by Mitsubishi gas chemical corporation, trade name "EPICLON CR-5L" manufactured by DIC corporation, trade name "Denacol EX-512" manufactured by Nagase Chemte X corporation, trade name "TEPIC-G" manufactured by Nissan chemical industry corporation, and the like.

The amount of the epoxy-based crosslinking agent used is not particularly limited. The amount of the epoxy-based crosslinking agent to be used can be set to, for example, more than 0 parts by weight and not more than about 1 part by weight (typically about 0.001 parts by weight to about 0.5 parts by weight) relative to 100 parts by weight of the base polymer. The amount of the epoxy-based crosslinking agent to be used is preferably about 0.002 parts by weight or more, more preferably about 0.005 parts by weight or more, and still more preferably about 0.008 parts by weight or more, based on 100 parts by weight of the base polymer, from the viewpoint of suitably exhibiting the effect of improving the cohesive force. The amount of the epoxy-based crosslinking agent to be used is preferably about 0.2 parts by weight or less, more preferably about 0.1 parts by weight or less, still more preferably about less than 0.05 parts by weight, and still more preferably about less than 0.03 parts by weight (for example, about 0.025 parts by weight or less) based on 100 parts by weight of the base polymer, from the viewpoint of improving the adhesion to an adherend. By reducing the amount of the epoxy-based crosslinking agent, impact resistance tends to be improved.

In the technology disclosed herein, the relation between the content of the isocyanate-based crosslinking agent and the content of the non-isocyanate-based crosslinking agent (e.g., epoxy-based crosslinking agent) is not particularly limited. The content of the non-isocyanate-based crosslinking agent can be set to, for example, about 1/50 or less of the content of the isocyanate-based crosslinking agent. The content of the non-isocyanate-based crosslinking agent is preferably set to about 1/75 or less, more preferably about 1/100 or less (for example, 1/150 or less) of the content of the isocyanate-based crosslinking agent on a weight basis, from the viewpoint of more suitably satisfying both the adhesion to an adherend and the cohesive strength. In addition, from the viewpoint of appropriately exhibiting the effect of using the isocyanate-based crosslinking agent and the non-isocyanate-based crosslinking agent (for example, the epoxy-based crosslinking agent) in combination, the content of the non-isocyanate-based crosslinking agent is set to about 1/1000 or more, for example, about 1/500 or more, and may be 1/250 or more, as appropriate.

The total amount (total amount) of the crosslinking agent used is not particularly limited. For example, the amount of the polymer is set to about 10 parts by weight or less based on 100 parts by weight of the base polymer (preferably, acrylic polymer), and the polymer can be selected from the range of preferably about 0.005 parts by weight to about 10 parts by weight, more preferably about 0.01 parts by weight to about 5 parts by weight.

(antirust agent)

Some preferred adhesive layers may contain rust inhibitors. The rust inhibitor is not particularly limited, and examples thereof include: azole rust inhibitors, amine compounds, nitrites, ammonium benzoate, ammonium phthalate, ammonium stearate, ammonium palmitate, ammonium oleate, ammonium carbonate, dicyclohexylamine benzoate, urea, urotropine, thiourea, phenyl carbamate, N-cyclohexylammonium carbamate (CHC), and the like. The rust inhibitor may be used singly or two or more kinds may be used in combination.

As the rust inhibitor, an azole rust inhibitor can be preferably used. As the azole rust inhibitor, an azole rust inhibitor containing a five-membered ring aromatic compound having two or more hetero atoms and an azole compound having at least one of these hetero atoms as a nitrogen atom as an active ingredient can be preferably used. As preferable examples of the compound which can be used as the azole rust inhibitor, benzotriazole rust inhibitors containing benzotriazole compounds as an active ingredient can be cited. Preferable examples of the benzotriazole-based compound include 1,2, 3-benzotriazole, 5-methylbenzotriazole, 4-methylbenzotriazole, and carboxybenzotriazole.

The content of the rust inhibitor is not particularly limited, and may be set to 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, for example. The content may be 0.1 part by weight or more, 0.3 parts by weight or more, or 0.5 parts by weight or more from the viewpoint of obtaining a more excellent effect of preventing metal corrosion. On the other hand, from the viewpoint of improving the cohesive force of the adhesive, the content of the rust inhibitor is suitably set to less than 8 parts by weight relative to 100 parts by weight of the base polymer, and may be set to 5 parts by weight or less, or may be set to 2 parts by weight or less.

(other additives)

The adhesive composition may contain various additives commonly used in the adhesive field, such as leveling agents, crosslinking aids, plasticizers, softeners, antistatic agents, anti-aging agents, ultraviolet absorbers, antioxidants, and light stabilizers, as required. As such various additives, conventionally known ones can be used by a conventional method, and are not characteristic of the present invention, and therefore, detailed description thereof is omitted.

(adhesive composition)

The adhesive layer (layer composed of an adhesive) disclosed herein may be an adhesive layer formed of an aqueous adhesive composition, a solvent-based adhesive composition, a hot-melt adhesive composition, an active energy ray-curable adhesive composition cured by irradiation of active energy rays such as ultraviolet rays or electron rays. The aqueous adhesive composition is an adhesive composition in a form including an adhesive (adhesive layer forming component) in a solvent (aqueous solvent) containing water as a main component, and typically includes a composition in a form of at least a part of the adhesive being dispersed in water, and the like, which is referred to as a water-dispersed adhesive composition. The solvent-type adhesive composition is an adhesive composition in a form containing an adhesive in an organic solvent. As the organic solvent contained in the solvent-type adhesive composition, one or two or more kinds of organic solvents (toluene, ethyl acetate, etc.) exemplified as the organic solvents usable in the above-mentioned solution polymerization can be used without particular limitation. The technology disclosed herein may be preferably implemented in such a manner as to have an adhesive layer formed of a solvent-type adhesive composition from the viewpoint of adhesive properties and the like. In the case of the method having the solvent-based adhesive layer formed of the solvent-based adhesive composition, the refractive index improving effect by the technique disclosed herein can be satisfactorily achieved.

As described above, according to the present specification, there is provided an adhesive composition comprising one or two or more of the components that may be contained in the adhesive layer disclosed herein. By using the adhesive composition, the adhesive sheet disclosed herein can be produced. The adhesive composition may contain, for example, an infrared ray absorber and a colorant different from the infrared ray absorber. Further, a component (typically a base polymer) that may be contained in the above-described adhesive layer may be contained. The content (wt% or parts by weight) of each component that can be contained in the adhesive layer may be referred to as the content (wt% or parts by weight) of the adhesive composition on a solid content basis (also referred to as a nonvolatile content basis). Details of the other adhesive compositions are as described in the adhesive layer, and thus, duplicate description is omitted.

(formation of adhesive layer)

The adhesive layer disclosed herein can be formed by a conventionally known method. For example, a method of forming an adhesive layer by applying an adhesive composition to a surface (release surface) having releasability and drying it can be employed. For the pressure-sensitive adhesive sheet having a structure of a support substrate, for example, a method (direct method) of forming a pressure-sensitive adhesive layer by directly applying (typically coating) a pressure-sensitive adhesive composition on the support substrate and drying the same can be employed. In addition, a method (transfer method) of forming an adhesive layer on a surface (release surface) having releasability by applying an adhesive composition to the surface and drying the composition, and transferring the adhesive layer to a support substrate may be employed. As the release surface, for example, a surface of a release liner described later can be preferably used. The adhesive layer disclosed herein is typically formed continuously, but is not limited to this, and may be formed in a regular or irregular pattern such as dots, stripes, or the like, for example.

The adhesive composition may be applied using a conventionally known coater such as a gravure roll coater, a die coater, or a bar coater. Alternatively, the adhesive composition may be applied by dipping, curtain coating, or the like.

Drying of the adhesive composition is preferably performed under heating from the viewpoints of promoting the crosslinking reaction, improving the production efficiency, and the like. The drying temperature may be set, for example, at about 40 to about 150 ℃, preferably at about 60 to about 130 ℃. After drying the adhesive composition, further curing may be performed for the purpose of adjusting the transfer of components in the adhesive layer, proceeding of the crosslinking reaction, relaxation of strain that may exist in the adhesive layer, and the like.

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

The thickness of the adhesive layer is not particularly limited. The thickness of the adhesive layer is preferably about 100 μm or less, more preferably about 70 μm or less, and still more preferably about 50 μm or less, from the viewpoint of avoiding the adhesive sheet from becoming excessively thick. The thickness of the pressure-sensitive adhesive layer may be set to about 35 μm or less, for example, about 25 μm or less, and further about 15 μm or less. The pressure-sensitive adhesive layer having a limited thickness can suitably meet the demand for thickness reduction and weight reduction. The lower limit of the thickness of the pressure-sensitive adhesive layer is not particularly limited, and is set to be favorably about 1 μm or more, preferably about 3 μm or more, more preferably about 10 μm or more, still more preferably about 15 μm or more, still more preferably about 20 μm or more, and may be about 30 μm or more, and may be about 35 μm or more, and may be about 40 μm or more, from the viewpoint of adhesion to an adherend. By setting the thickness to be equal to or greater than a predetermined value, the visible light transmittance and the infrared light transmittance equal to or less than the predetermined value can be easily achieved, and further, the masking of the adherend and the blocking of infrared light can be easily achieved. In addition, desired adhesive properties (adhesive strength, impact resistance, etc.) are easily obtained. In the 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 may have the same thickness or may have different thicknesses.

(visible light transmittance)

The transmittance (visible light transmittance) of light rays in the wavelength range of 380nm to 550nm constituting the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet disclosed herein is preferably limited to a predetermined value or less. The adhesive sheet can mask an adherend with the use of the restricted visible light transmittance of the adhesive layer like this. The visible light transmittance of the pressure-sensitive adhesive layer (in other words, the maximum value of the transmittance of light in the wavelength range of 380nm to 550 nm) is preferably 20% or less, more preferably 15% or less, still more preferably 10% or less, and may be 8% or less, or may be 6% or less. The lower the visible light transmittance, the more excellent the masking property can be exhibited. The lower limit of the visible light transmittance (in other words, the minimum value of the transmittance of light in the wavelength range of 380nm to 550 nm) is not particularly limited, and may be substantially 0%, that is, not more than the detection limit, and may be 0.01% 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 value of the transmittance of light in the wavelength range of 380nm to 550 nm) may be 2.0% or more, may be 3.0% or more, or may be 4.0% or more. By improving the visible light transmittance, the adherend can be visually recognized and inspected through the adhesive sheet. The visible light transmittance of the adhesive layer can be measured by the method described in examples described later.

(Infrared transmittance)

The transmittance (infrared transmittance) of light rays in the wavelength range of 800nm to 1500nm constituting the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet disclosed herein is preferably limited to a predetermined value or less. Thus, the pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer can block infrared rays. For example, according to the pressure-sensitive adhesive layer, occurrence of defects caused by the passage of infrared rays, such as a decrease in the operation accuracy of the infrared sensor and malfunction, can be prevented by the infrared blocking property of the pressure-sensitive adhesive layer without being limited by the material and shape of the adherend. The infrared transmittance of the pressure-sensitive adhesive layer (in other words, the maximum value of the transmittance of light in the wavelength range of 800nm to 1500 nm) is preferably 5.0% or less, more preferably 4.0% or less, further preferably 3.0% 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 the transmittance of light in the wavelength range of 800nm to 1500 nm) is not particularly limited, and may be substantially 0%, that is, not more than the detection limit, not less than 0.01%, not less than 0.05%, not less than 0.1%, not less than 0.2%, or not less than 0.3%. The infrared transmittance of the adhesive layer can be measured by the method described in examples described later.

The relative relationship between the visible light transmittance and the infrared light transmittance of the pressure-sensitive adhesive layer is not particularly limited, and may be appropriately set so as to achieve a relationship between the adherend masking property and the infrared light blocking property. For example, the infrared transmittance T of the adhesive layer _IR [％]And visible light transmittance T _VL [％]Difference (T) _VL -T _IR ) For example, 15 or less, 10 or less, 5 or less, or 3 or less. With the above difference (T _VL -T _IR ) The smaller theThe better the masking of the adherend tends to be. In addition, the difference (T _VL -T _IR ) For example, the content may be 0.1 or more, 0.5 or more, 1 or more, 1.5 or more, 1.8 or more, or 2 or more. With difference (T) _VL -T _IR ) The larger the infrared ray blocking tends to be more excellent. After calculating the above difference (T _VL -T _IR ) At the time of the above-mentioned infrared transmittance T _IR The maximum value [%of transmittance of light having a wavelength of 800-1500 nm is used]As the visible light transmittance T _VL Using the minimum value [%of the transmittance of light in the wavelength range of 380nm to 550nm]。

< support substrate >)

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 base material, a resin film, paper, cloth, a rubber sheet, a composite of these, or the like can be used as the base material for supporting (backing) the pressure-sensitive adhesive layer. Examples of the resin film include: polyolefin films such as Polyethylene (PE), polypropylene (PP), and ethylene-propylene copolymers; polyester films such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN); a vinyl chloride resin film; vinyl acetate resin film; a polyimide resin film; a polyamide resin film; a fluorine-containing resin film; cellophane (cellophane), and the like. As examples of the paper, there may be mentioned: japanese paper, kraft paper, cellophane, quality paper, synthetic paper, surface-coated paper, and the like. Examples of the cloth include woven fabrics and nonwoven fabrics obtained by blending various fibrous materials alone or in combination. Examples of the fibrous material include: cotton, staple fibers, abaca, pulp, rayon, acetate, polyester, polyvinyl alcohol, polyamide, polyolefin, and the like. Examples of the rubber sheet include: natural rubber sheets, butyl rubber sheets, and the like.

The term "nonwoven fabric" as used herein mainly refers to a concept of nonwoven fabric for an adhesive sheet used in the field of an adhesive tape and other adhesive sheets, and typically refers to a nonwoven fabric (sometimes referred to as "paper") produced by using a general paper machine. The resin film herein is typically a non-porous resin sheet, and is distinguished from, for example, a nonwoven fabric or a woven fabric (in other words, a concept excluding a nonwoven fabric or a woven fabric). The resin film may be any of a non-stretched film, a uniaxially stretched film, and a biaxially stretched film.

As the support base material constituting the adhesive sheet with a base material, a support base material containing a resin film as a base film can be preferably used. The base film is typically a (independent) member that can independently maintain shape. The support substrate in the technology disclosed herein may consist essentially of such a base film. Alternatively, the support substrate may include an auxiliary layer in addition to the base film. Examples of the auxiliary layer include a colored layer, a reflective layer, an undercoat layer, and an antistatic layer provided on the surface of the base film.

The resin film is a film containing a resin material as a main component (for example, the resin film contains more than 50% by weight of the component). From the viewpoints of handleability and processability, a polyester film is preferable, and among these, a PET film is particularly preferable.

The support substrate may be a transparent support substrate or a masking support substrate. In some embodiments, a colorant may be contained in a support substrate (e.g., a resin film). Thereby, the light transmittance of the support substrate can be adjusted. Adjusting the light transmittance (e.g., visible light transmittance) of the support substrate helps to adjust the light transmittance of the support substrate, and further helps to adjust the light transmittance of an adhesive sheet comprising the substrate.

As the colorant, pigments and dyes known in the prior art can be used, as can the colorant that can be contained in the adhesive layer. The colorant is not particularly limited, and may be, for example, black, gray, white, red, blue, yellow, green, yellow-green, orange, violet, gold, silver, pearl, or the like. The amount of the colorant used in the support substrate (e.g., resin film) is not particularly limited, and may be set to an amount appropriately adjusted so that desired optical characteristics can be imparted.

The support base material (for example, a resin film) may be blended with various additives such as a filler (inorganic filler, organic filler, etc.), a dispersant (surfactant, etc.), an anti-aging agent, an antioxidant, an ultraviolet absorber, an antistatic agent, a lubricant, a plasticizer, etc., as required. The blend ratio of the various additives may be less than about 30 wt% (e.g., less than about 20 wt%, typically less than about 10 wt%).

The support base material (for example, a resin film) may have a single-layer structure, or may have a multilayer structure of two layers, three layers, or more than three layers. From the viewpoint of shape stability, the support base material is preferably of 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 above-mentioned resin (for example, polyester-based resin). The method for producing the support base material (typically, a resin film) is not particularly limited, and conventionally known methods can be suitably employed. For example, conventionally known usual film molding methods such as extrusion molding, inflation molding, T-die casting molding, and calender roll molding can be suitably employed.

The support substrate may be colored by a coloring layer disposed on the surface of a base film (preferably, a resin film). In the base material having such a structure including the base film and the coloring layer, the base film may or may not contain a coloring agent. The colored layer may be disposed on any one surface of the base film or may be disposed on both surfaces. In the constitution in which the coloring layers are disposed on both surfaces of the base film, the constitution of these coloring layers may be the same or different.

Such a colored layer can be typically formed by coating a base film with a colored layer-forming composition containing a colorant and a binder. As the colorant, pigments and dyes known in the prior art can be used, similarly to the colorant that may be contained in the adhesive layer and the resin film. As the binder, materials known in the field of paint or printing can be used without particular limitation. Examples may include: polyurethane, phenolic resin, epoxy resin, urea melamine resin, polymethyl methacrylate, and the like. The coloring layer-forming composition may be, for example, solvent-based, ultraviolet-curable, or thermosetting. The colored layer may be formed by any means conventionally used for forming a colored layer without particular limitation. For example, a method of forming a colored layer (printed layer) by printing such as gravure printing, flexography, or offset printing can be preferably employed.

The colored layer may have a single-layer structure composed of one layer as a whole, or may have a multi-layer structure including two, three, or more sub-colored layers. The colored layer having a multilayer structure including two or more sub-colored layers can be formed, for example, by repeating the application (e.g., printing) of the composition for forming a colored layer. The color and the amount of the colorant contained in each sub-coloring layer may be the same or different. Among the colored layers for imparting masking properties, it is particularly interesting to make a multilayer structure from the viewpoint of preventing the occurrence of pinholes.

The thickness of the colored layer as a whole is suitably from about 1 μm to about 10. Mu.m, preferably from about 1 μm to about 7. Mu.m, and for example, from about 1 μm to about 5. Mu.m. In the colored layer including two or more sub-colored layers, the thickness of each sub-colored layer is preferably about 1 μm to about 2 μm.

The thickness of the support substrate is not particularly limited. From the viewpoint of avoiding the pressure-sensitive adhesive sheet from becoming excessively thick, the thickness of the support substrate may be set to, for example, about 200 μm or less (for example, about 100 μm or less). The thickness of the support substrate may be about 70 μm or less, about 30 μm or less, or about 15 μm or less (for example, about 8 μm or less) depending on the purpose of use and the mode of use of the adhesive sheet. The lower limit of the thickness of the support substrate is not particularly limited. The thickness of the support base material is preferably about 2 μm or more, more preferably about 5 μm or more, for example about 10 μm or more, from the viewpoint of handleability (handleability), workability, and the like of the adhesive sheet.

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, and primer coating. Such a surface treatment may be a treatment for improving the adhesion between the support substrate and the adhesive layer, in other words, the anchoring property of the adhesive layer to the support substrate.

In the case where the technology disclosed herein is implemented in the form of a single-sided pressure-sensitive adhesive sheet with a base material, the back surface of the support base material may be subjected to a peeling treatment as needed. The release treatment may be, for example, a treatment of applying a release treatment agent such as a general silicone, long-chain alkyl, fluorine, etc., typically in the form of a film of about 0.01 μm to about 1 μm (for example, about 0.01 μm to about 0.1 μm). By performing the peeling treatment, the effect of easily unwinding the roll of the adhesive sheet into a roll can be obtained.

< Release liner >)

In the technology disclosed herein, a release liner may be used in the formation of an adhesive layer, the production of an adhesive sheet, the preservation of an adhesive sheet before use, circulation, shape processing, and the like. The release liner is not particularly limited, and for example, a release liner having a release treatment layer on the surface of a liner substrate such as a resin film or paper; a release liner comprising a low-tackiness material such as a fluoropolymer (polytetrafluoroethylene or the like) or a polyolefin resin (polyethylene, polypropylene or the like). The release treatment layer may be formed by surface-treating the gasket base material with a release treatment agent such as silicone, long-chain alkyl, fluorine, or molybdenum sulfide.

< usage >

The pressure-sensitive adhesive sheet disclosed herein is suitable for various applications requiring masking of an adherend by taking advantage of the characteristics of the pressure-sensitive adhesive sheet because the adherend can be masked. For example, in a portable electronic device, there is a device that requires masking of a member or the like by an adhesive sheet. The adhesive sheet disclosed herein is preferably used for fixing the components of such a portable electronic device.

Non-limiting examples of such portable electronic devices include: a mobile phone, a smart phone, a tablet personal computer, a notebook personal computer, various wearable devices (for example, wrist wearing type worn on a wrist such as a wristwatch, modularized type worn on a part of a body with a clip, a band, or the like, eye wearing (eye wearing) type including glasses type (monocular type, binocular type, helmet type is also included), clothing type worn on a shirt, socks, hat, or the like in the form of, for example, ornaments, ear wearing type worn on an ear such as an earphone, or the like), a digital camera, a digital video camera, an acoustic device (portable music player, recording pen, or the like), a calculator (desktop calculator, or the like), a portable game device, an electronic dictionary, an electronic notepad, an electronic book, a vehicle-mounted information device, a portable radio, a portable television, a portable printer, a portable scanner, a portable modem, or the like. It should be noted that "portable" in this specification is interpreted as being insufficient to be portable only, and it is actually portable at a level that an individual (standard adult) can relatively easily carry. Examples of the electronic device include a personal computer (desktop, notebook, tablet, etc.), a television, and the like. These may be devices incorporating display devices (display apparatuses) such as liquid crystal and organic Electroluminescence (EL).

The adhesive sheet disclosed herein may be used, for example, for the purpose of fixing a pressure-sensitive sensor with other members in a portable electronic device having the pressure-sensitive sensor in such a portable electronic device. In some modes, the adhesive sheet may be used for fixing the pressure-sensitive sensor and other members in an electronic apparatus (typically a portable electronic apparatus) having a function capable of specifying an absolute position on a board (typically a touch panel) corresponding to a screen by means of a means for indicating a position on the screen (typically a pen-type, mouse-type means) and a means for detecting a position.

In addition, the adhesive sheet disclosed herein is suitable for the following uses: a back surface of a display screen (display unit) such as a touch panel display disposed in a portable electronic device. By disposing the pressure-sensitive adhesive sheet disclosed herein on the back surface of the display screen (display unit), it is possible to prevent the visual visibility of the display screen from being lowered regardless of the manner of use of the portable electronic device.

In addition, the adhesive sheet disclosed herein is suitable for portable electronic devices incorporating light sensors. For the purpose of operation of the apparatus, sensing of an approaching object, detection of surrounding brightness (ambient light), data communication, and the like, various apparatuses such as the above-described portable electronic apparatus may have a photosensor that uses light rays such as infrared rays, visible rays, ultraviolet rays, and the like. The optical sensor is not particularly limited, but examples thereof include an acceleration sensor, a proximity sensor, a luminance sensor (ambient light sensor), and the like. Such a photosensor may have a light receiving element for receiving light rays such as ultraviolet rays, visible rays, and infrared rays, or may have a light emitting element for emitting specific light rays such as infrared rays. In other words, the light sensor may contain a light emitting element and/or a light receiving element that contain light rays of a specific wavelength region among wavelength regions of ultraviolet rays, visible rays, and infrared rays. The pressure-sensitive adhesive sheet disclosed herein is one that does not adversely affect the accuracy of the operation of the sensor, and therefore can be satisfactorily used as a masking unit or an adhesive unit in the apparatus as described above.

As a preferable application object of the pressure-sensitive adhesive sheet disclosed herein, an electronic device incorporating an infrared sensor can be cited. The pressure-sensitive adhesive sheet disclosed herein can have excellent infrared ray blocking properties, and therefore, when used for the purpose of fixing, protecting, covering, and sealing components of the electronic device, etc., infrared rays can be effectively blocked, and the influence on the accuracy of operation of the infrared ray sensor due to light from the outside can be reduced. Such an electronic device may have a biometric authentication function that uses a biometric authentication technique for authenticating an individual based on biometric information such as a fingerprint or vein. An infrared sensor may be used for such personal authentication. Examples of the electronic device include a portable electronic device having a biometric authentication function capable of performing personal authentication by using a fingerprint or the like, and various biometric authentication devices.

Further, as another preferable example of the electronic device (typically, a portable electronic device) having an infrared sensor incorporated therein, a device such as a remote controller (remote operation device) that performs an operation of a main body using the infrared sensor may be mentioned. In such a device, since it is not desirable that infrared rays leak from outside the light emitting portion toward the object, it is particularly interesting to block infrared rays using the adhesive sheet disclosed herein to prevent infrared rays emitted from inside the device from leaking from outside the light emitting portion. By using the technology disclosed herein in the above-described application, it is possible to prevent a reduction in the operation accuracy and malfunction of the infrared sensor.

The material (adherend material) to which the pressure-sensitive adhesive sheet disclosed herein is attached is not particularly limited, and examples thereof include: examples of the metal material include metal materials such as copper, silver, gold, iron, tin, palladium, aluminum, nickel, titanium, chromium, zinc, and an alloy containing two or more of them, and examples include various resin materials (typically, plastic materials), such as polyimide resins, acrylic resins, polyether nitrile resins, polyether sulfone resins, polyester resins (PET resins, polyethylene naphthalate resins, and the like), polyvinyl chloride resins, polyphenylene sulfide resins, polyether ether ketone resins, polyamide resins (so-called aramid resins, and the like), polyarylate resins, polycarbonate resins, and liquid crystal polymers, and inorganic materials such as alumina, zirconia, sodium glass, quartz glass, and carbon. Among them, metallic materials such as copper, aluminum, and stainless steel, resin materials (typically plastic materials) such as polyester resins such as PET, polyimide resins, aramid resins, and polyphenylene sulfide resins are widely used. The material may be a material constituting a member of a product such as an electronic device. The adhesive sheet disclosed herein can be used by being stuck to a member made of the above-mentioned material. The material may be a material constituting a fixed object (for example, a back surface member such as an electromagnetic wave shield or a reinforcing plate) such as the pressure-sensitive sensor or the display unit. The fixed object is an object to which the adhesive sheet is attached, that is, an adherend. The back surface member is a member disposed on the opposite side of the front surface (visual recognition side) of the pressure-sensitive sensor and the display portion in the portable electronic device, and may be a member constituting a support portion 240 disposed on the back surface of the display device 200 shown in fig. 3, which will be described later. The fixing object may have a single-layer structure or a multi-layer structure, or may be formed by subjecting the surface (the adhesive surface) of the adhesive sheet to various surface treatments. Although not particularly limited, as an example of the object to be fixed, there is a back surface member having a thickness of about 1 μm or more (typically about 5 μm or more, for example about 60 μm or more, further about 120 μm or more) and about 1500 μm or less (for example about 800 μm or less).

The adhesive sheet disclosed herein is suitable for use in masking at least a part of a surface (adhesive sheet adhering surface) of a member or article made of a metal material such as aluminum or stainless steel. Preferable examples of such an adherend include metal members such as stainless steel members and aluminum members. The above-mentioned region of the metal member can be masked by attaching an adhesive sheet to the region of the metal member surface where masking is required. The adhesive sheet may be an adhesive sheet covering the entire surface of the metal member, or may be an adhesive sheet covering a part of the surface (a part of the area requiring masking). The metal member may be, for example, a member constituting a support portion 240 of the display device 200 shown in fig. 3 described later. In the case where the pressure-sensitive adhesive sheet is a double-sided pressure-sensitive adhesive sheet, and different adherends (members or articles) are attached to each side of the pressure-sensitive adhesive sheet, it is preferable that one of the adherends is a metal member.

The pressure-sensitive adhesive sheet disclosed herein is suitable for use in masking the surface of a metal member subjected to processing such as opening. The pressure-sensitive adhesive sheet used for this purpose may cover the adherend including a region where a metal member as the adherend is not locally present, and mask the adherend. Therefore, the surface (adhesive surface) of the adhesive sheet may have a region where an adherend is present (adherend-adhering region) and a region where no adherend is present (adherend-non-adhering region). In this case, although infrared rays can pass through the pressure-sensitive adhesive sheet and the region where the adherend is not present, by using the infrared ray blocking pressure-sensitive adhesive sheet disclosed herein, infrared rays can be blocked even in the region where the metal member as the adherend is not present, and malfunction of the photosensor or the like can be prevented.

The member or material to be adhered to the pressure-sensitive adhesive sheet (at least one adherend in the case of a double-sided pressure-sensitive adhesive sheet) may be a member or material having light transmittance. According to the technology disclosed herein, the masking can be performed by the pressure-sensitive adhesive sheet (specifically, masking of the surface of another adherend in the case of the double-sided pressure-sensitive adhesive sheet) through the light-transmissive adherend as described above. In addition, since the light of the sensor passes through the adherend and reaches the pressure-sensitive adhesive sheet, the light-transmitting adherend has an advantage that the effect (infrared ray blocking) produced by the technology disclosed herein can be easily obtained. The visible light transmittance of the adherend (member or the like) having the above light transmittance may be, for example, 5% or more, or 30% or more. In some embodiments, the visible light transmittance of the light-transmissive member or the like is, for example, greater than 50%, preferably 70% or more, more preferably 80% or more, still more preferably 90% or more, and may be 95% or more. Such a material may be a resin film (for example, a polyester resin film such as a PET film) disposed on the back surface of an image display portion of various devices such as a portable electronic device. The pressure-sensitive adhesive sheet disclosed herein can be satisfactorily used so as to be adhered to an adherend (e.g., 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 that of the adhesive sheet.

As described above, according to the technology disclosed herein, a laminate having 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). The laminate may have a metal member and an adhesive sheet covering at least a portion of a surface of the metal member. The adhesive sheet may be an adhesive sheet covering the entire surface of the metal member, or may be an adhesive sheet covering a part of the surface (a part of the area requiring masking). Typically, one surface (adhesive surface) of the adhesive sheet is adhered to the metal member. In some embodiments, the member to which the adhesive sheet is attached may be a member having the transmittance of light of the adherend material described above. In this embodiment, the laminate including the adhesive sheet is a laminate including the adhesive sheet and a member (second member) having light transmittance. In some preferred embodiments, the laminate is a laminate having a metal member (first member), an adhesive sheet, and a member having light transmittance (second member) in this order. The pressure-sensitive adhesive sheet is also referred to as a pressure-sensitive adhesive layer in the laminate.

Fig. 2 illustrates the structure of the laminate. The laminate 50 shown in fig. 2 has a first member 41, a base-material-free 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 base-material-free adhesive sheet 1 is adhered to the first member 41, and the other adhesive surface (second adhesive surface) 1B of the adhesive sheet 1 is adhered to the second member 42. In this embodiment, each of the first member 41 and the second member 42 has a sheet-like or plate-like shape, and the laminated body 50 has a multilayer structure. Details of members constituting the laminate are as described above for the members, materials, and adherends, and thus, the description thereof will not be repeated.

In some preferred embodiments, the first member 41 is a metal member, and a metal material exemplified as the adherend material described above is used. The metal member of the first member 41 is preferably an aluminum member or a stainless steel member, and more preferably a stainless steel member. By attaching the adhesive sheet 1 disclosed herein to a metal member as the first member 41, the metal member can be well masked. Such a metal member may be, for example, a member constituting a support portion 240 of the display device 200 shown in fig. 3 described later. In some preferred embodiments, the second member 42 is a light-transmissive member having the light transmittance of the light-transmissive adherend. 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 disposed on the back surface side of the display unit in the display device. The laminate 50 as described above may be typically a constituent element of an organic EL display device, a liquid crystal display device, or the like. The laminate 50 is suitable for use, for example, in a back surface of an image display portion (display portion such as a touch panel display) of various devices such as a portable electronic device.

The adhesive sheet disclosed herein is satisfactorily 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, the present invention can be satisfactorily used in electronic devices (typically portable electronic devices) having an organic EL display device and a liquid crystal display device, which require predetermined optical characteristics.

Fig. 3 is an exploded perspective view schematically showing an exemplary configuration of the display device. As shown in fig. 3, the display device 200 included in the portable electronic device 100 includes a support portion 240 and a display portion 220 including a cover member, an organic EL unit, and the like. The display device 200 further includes an adhesive sheet 230. In this configuration example, the pressure-sensitive adhesive sheet 230 is a double-sided pressure-sensitive adhesive sheet (double-sided pressure-sensitive adhesive sheet) for fixing members constituting the display unit 220 and the support unit 240. The support portion 240 is configured to include a substrate (a metal plate such as a stainless steel plate or an aluminum plate) or the like. The adhesive sheet disclosed herein is satisfactorily used as a constituent element of a display device as described above.

The matters disclosed in the present specification include the following matters.

[1] A display device includes a display portion including a cover member and an organic EL unit, and a support portion, wherein,

An adhesive sheet is adhered to the supporting portion,

the adhesive sheet has an adhesive layer and,

the transmittance of the adhesive sheet for light rays in the wavelength range of 380nm to 550nm is 20% or less, and the transmittance of the adhesive sheet for light rays in the wavelength range of 800nm to 1500nm is 5% or less.

[2] The display device according to the above [1], wherein the adhesive layer contains an infrared absorber (preferably, the infrared absorber is a metal compound) and a colorant different from the infrared absorber.

[3] The display device described in the above [1] or [2], wherein the adhesive layer contains at least one selected from tungsten composite oxide and tin composite oxide as an infrared absorber.

[4] The display device according to any one of [1] to [3], wherein the adhesive layer contains a black colorant as a colorant.

[5] The display device described in [4] above, wherein the adhesive layer further contains a metal oxide as a colorant.

[6] The display device according to any one of [1] to [5], wherein the total amount of the infrared absorber and the colorant contained in the pressure-sensitive adhesive layer is in the range of 5 to 30 parts by weight based on 100 parts by weight of the base polymer contained in the pressure-sensitive adhesive layer.

[7] The display device according to any one of [1] to [6], wherein the adhesive layer is an acrylic adhesive layer containing an acrylic polymer as a base polymer.

[8] The display device according to any one of [1] to [7], wherein a thickness of the adhesive layer is in a range of 10 μm to 50 μm.

[9] The display device according to any one of [1] to [8], wherein the pressure-sensitive adhesive sheet is a substrate-free double-sided pressure-sensitive adhesive sheet composed of the pressure-sensitive adhesive layer.

[10] The display device according to any one of [1] to [9], wherein the 180-degree peel strength of the adhesive sheet to a stainless steel sheet measured based on JIS Z0237 is 10N/25mm or more.

[11] An adhesive sheet comprising an adhesive layer, wherein the adhesive sheet has a light transmittance of 20% or less in the wavelength range of 380nm to 550nm and a light transmittance of 5% or less in the wavelength range of 800nm to 1500 nm.

[12] The adhesive sheet according to the above [11], wherein the adhesive layer contains an infrared absorber (preferably, the infrared absorber is a metal compound) and a colorant different from the infrared absorber, and more preferably, the adhesive layer contains at least one selected from the group consisting of tungsten composite oxides and tin composite oxides as an infrared absorber.

[13] The adhesive sheet according to the above [11] or [12], wherein the adhesive layer contains a black colorant as a colorant.

[14] The adhesive sheet according to the above [13], wherein the adhesive layer further comprises a metal oxide as a colorant.

[15] The adhesive sheet according to any one of [11] to [14], wherein the total amount of the infrared absorber and the colorant contained in the adhesive layer is in the range of 5 to 30 parts by weight based on 100 parts by weight of the base polymer contained in the adhesive layer.

[16] The adhesive sheet according to any one of [11] to [15], wherein the adhesive layer is an acrylic adhesive layer containing an acrylic polymer as a base polymer.

[17] The adhesive sheet according to any one of [11] to [16], wherein the thickness of the adhesive layer is in the range of 10 μm to 50 μm.

[18] The adhesive sheet according to any one of [11] to [17], wherein the adhesive sheet is a substrate-free double-sided adhesive sheet composed of the adhesive layer.

[19] The adhesive sheet according to any one of [11] to [18], wherein the adhesive sheet has a 180-degree peel strength to a stainless steel sheet of 10N/25mm or more as measured according to JIS Z0237.

[20] The adhesive sheet according to any one of [11] to [19], wherein the adhesive sheet is used for fixing a member of a portable electronic device.

[21] A laminate having a metal member and an adhesive sheet adhered to a surface of the metal member, wherein,

the adhesive sheet has an adhesive layer and,

[22] A laminate having an adhesive sheet and a member having light transmittance, wherein,

one surface of the adhesive sheet is adhered to the light-transmitting member,

the adhesive sheet has an adhesive layer and,

[23] A laminate comprising, in order, a metal member (first member), an adhesive sheet, and a member (second member) having light transmittance,

the adhesive sheet has an adhesive layer and,

[24] The laminate according to [21] or [23], wherein the metal member is an aluminum member or a stainless steel member.

[25] The laminate according to [22] or [23], wherein the light transmittance of the light-transmissive member is more than 50%.

[26] The laminate according to [22], [23] or [25], wherein the light-transmitting member is composed of a resin film.

[27] The laminate according to any one of [21] to [26], wherein the pressure-sensitive adhesive layer contains an infrared absorber (preferably, the infrared absorber is a metal compound) and a colorant different from the infrared absorber.

[28] The laminate according to any one of [21] to [27], wherein the adhesive layer contains at least one selected from the group consisting of tungsten composite oxides and tin composite oxides as an infrared absorber.

[29] The laminate according to any one of [21] to [28], wherein the adhesive layer contains a black colorant as a colorant.

[30] The laminate according to the above [29], wherein the adhesive layer further comprises a metal oxide as a colorant.

[31] The laminate according to any one of [21] to [30], wherein the total amount of the infrared absorber and the colorant contained in the adhesive layer is in the range of 5 to 30 parts by weight based on 100 parts by weight of the base polymer contained in the adhesive layer.

[32] The laminate according to any one of [21] to [31], wherein the adhesive layer is an acrylic adhesive layer containing an acrylic polymer as a base polymer.

[33] The laminate according to any one of [21] to [32], wherein the thickness of the adhesive layer is in the range of 10 μm to 50 μm.

[34] The laminate according to any one of [21] to [33], wherein the pressure-sensitive adhesive sheet is a substrate-free double-sided pressure-sensitive adhesive sheet comprising the pressure-sensitive adhesive layer.

[35] The laminate according to any one of [21] to [34], wherein the 180-degree peel strength of the adhesive sheet to a stainless steel sheet measured according to JIS Z0237 is 10N/25mm or more.

[36] The laminate according to any one of [21] to [35], wherein the laminate is used for a portable electronic device.

Examples

In the following, several embodiments related to the present invention will be described, but the present invention is not limited to the embodiments described above. In the following description, unless otherwise specified, "parts" are weight basis.

< evaluation method >)

[ visible light transmittance and Infrared transmittance ]

The visible light transmittance [% ] and the infrared light transmittance [% ] of the pressure-sensitive adhesive layer and the pressure-sensitive adhesive sheet were obtained by measuring the visible light transmittance (wavelength range 380nm to 550 nm) and the infrared light transmittance (wavelength range 800nm to 1500 nm) in the thickness direction of the pressure-sensitive adhesive layer and the pressure-sensitive adhesive sheet peeled from the release liner, respectively, using a commercially available spectrophotometer. As the spectrophotometer, a spectrophotometer manufactured by hitachi manufacturing (apparatus name "UH4150 type spectrophotometer") or an equivalent thereof can be used.

[180 degree peel Strength (adhesive force) ]

A PET film having a thickness of 50 μm was adhered to one surface of a double-sided pressure-sensitive adhesive sheet at 23℃under a measurement environment of 50% RH, and the sheet was backed with a backing, and cut into dimensions of 25mm in width and 100mm in length, to thereby prepare a measurement sample. For the measurement sample thus prepared, a 2kg roller was reciprocated at 23℃under 50% RH, and the adhesive surface of the measurement sample was pressed against the surface of a stainless steel plate (SUS 304BA plate). It was left under the same environment for 30 minutes, and then using a universal tensile compression tester according to JIS Z0237: 2000, peel strength (adhesive force) [ N/25mm ] was measured under conditions of a tensile speed of 300 mm/min and a peel angle of 180 degrees. As the universal tensile compression tester, for example, "tensile compression tester, TG-1kN" manufactured by Minebea corporation, or an equivalent thereof may be used. In the case of the single-sided pressure-sensitive adhesive sheet, the backing of the PET film is not required.

[ shear adhesion force ]

The pressure-sensitive adhesive sheet (double-sided pressure-sensitive adhesive sheet) was cut into dimensions of 10mm×10mm, whereby a measurement sample was produced. The bonding surfaces of the measurement samples were each superposed on the surface of 2 stainless steel plates (SUS 304BA plates) at 23 ℃ and 50% rh, and a 2kg roller was reciprocated 1 time to press them. This was left to stand under the same environment for 2 days, and then the shear adhesion [ MPa ] was measured using a tensile tester under conditions of a tensile speed of 10 mm/min and a peeling angle of 0 degree. In the case of a pressure-sensitive adhesive sheet having single-sided tackiness (single-sided pressure-sensitive adhesive sheet), the non-tacky surface of the sheet may be fixed to a stainless steel plate by an adhesive or the like, and the measurement may be performed in the same manner as described above. As the tensile tester, a universal tensile compression tester (product name "TG-1kN", manufactured by Minebea Corp.) was used.

[ masking by adherend ]

A stainless steel plate was prepared as an adherend, and a mark (black mark) having a length of 10mm was marked on the surface thereof with a commercially available black oil marker (Mark pen). An adhesive sheet was adhered to the surface of the adherend, and an evaluation sample was produced. 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. The following 2 benchmarks were evaluated.

And (2) the following steps: black marks cannot be visually recognized.

X: the black mark can be visually recognized.

In the above evaluation, it was determined that the black mark could not be visually recognized as being able to mask the adherend.

[ Infrared Barrier Property ]

An adhesive sheet is bonded to a circuit pattern forming surface of a substrate having a circuit pattern formed on the surface thereof. The circuit pattern was a pattern of aluminum wiring with a line width of 1 mm. Next, the circuit pattern on the surface of the substrate was checked via the adhesive sheet by using an infrared microscope, and evaluated according to the following 2 criteria. As the infrared microscope, a composite device of a solid microscope (trade name "SMZ745T", manufactured by nikon corporation) and an infrared camera (trade name "MC781P0030", manufactured by texas instruments corporation) or an equivalent thereof may be used.

And (2) the following steps: 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)

Into a reaction vessel having a stirrer, a thermometer, a nitrogen inlet pipe, a reflux condenser and a dropping funnel, 95 parts of n-Butyl Acrylate (BA) as a monomer component, 5 parts of Acrylic Acid (AA) and 233 parts of ethyl acetate as a polymerization solvent were charged, and stirred for 2 hours while introducing nitrogen. Thus, oxygen in the polymerization system was removed, and then 0.2 part of 2,2' -Azobisisobutyronitrile (AIBN) was added as a polymerization initiator, and solution polymerization was performed at 60 ℃ for 8 hours, thereby obtaining a solution of an acrylic polymer. The acrylic polymer has a Mw of about 70X 10 ⁴ 。

(preparation of adhesive composition)

To the acrylic polymer solution described above, 20 parts of a terpene phenol resin as a tackifying resin, 3 parts of an isocyanate-based crosslinking agent as a crosslinking agent, 0.02 part of an epoxy-based crosslinking agent, 3 parts of carbon black particles (trade name "Multi rack a903" manufactured by eastern color corporation) as a colorant (black colorant), and 5 parts of cesium-containing tungsten composite oxide fine particles (product name "YMF-02", average dispersed particle diameter 50nm manufactured by sumitomo metal mine corporation) as an infrared absorbent a were added on a solid content basis with respect to 100 parts of the acrylic polymer contained in the solution, and stirred and mixed, thereby preparing an adhesive composition. As the terpene phenol resin (tackifying resin), the trade name "YS Polystar T-115" (manufactured by Anyuan chemical Co., ltd., softening point of about 115 ℃ C., hydroxyl value of 30mgKOH/g to 60 mgKOH/g) was used. As the isocyanate-based crosslinking agent, the product name "CORONATE L" (75% ethyl acetate solution of trimethylolpropane/toluene diisocyanate trimer adduct manufactured by Tosoh Co., ltd.) was used. As the epoxy-based crosslinking agent, the trade name "TETRAD-C" (1, 3-bis (N, N-diglycidyl aminomethyl) cyclohexane manufactured by Mitsubishi gas chemical corporation) was used.

(production of adhesive sheet)

The adhesive composition was applied to a release surface of a release liner made of polyester (trade name "DIAFOIL MRF", manufactured by Mitsubishi polyester Co., ltd.) having a thickness of 38. Mu.m, and dried at 100℃for 2 minutes, thereby forming an adhesive layer having a thickness of 30. Mu.m. A release liner made of polyester (trade name "DIAFOIL MRF", manufactured by Mitsubishi polyester Co., ltd.) having a thickness of 25 μm was laminated on the adhesive layer. Thus, a substrate-free double-sided pressure-sensitive adhesive sheet having a thickness of 30 μm and double-sided 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-based crosslinking agent as a crosslinking agent, 0.02 part of the epoxy-based crosslinking agent, 0.5 part of the carbon black particles as a first colorant (black colorant), and 10 parts of titanium oxide (TiO) as a second colorant (white colorant) were added based on the solid content, based on 100 parts of the acrylic polymer contained in the solution ₂ ) The binder composition of this example was prepared by mixing 10 parts of the cesium-containing tungsten composite oxide fine particles (product name "WHITEPASTER-2228", manufactured by Dai Seiki industries, ltd., average particle diameter of 50 nm) with stirring. A substrate-free double-sided adhesive sheet of this example was produced in the same manner as in example 1, except that the obtained 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-based crosslinking agent as a crosslinking agent, 0.02 parts of the epoxy-based crosslinking agent, 1.0 part of the carbon black particles as a first colorant (black colorant), 10 parts of the titanium oxide particles as a second colorant (white colorant), and 18 parts of antimony-doped tin oxide particles as an infrared absorber B (manufactured by sumitomo metal mine company under the product name "FMF-3 A1") were added on a solid content basis to the acrylic polymer solution, and the mixture was stirred and mixed to prepare an adhesive composition of this example. A substrate-free double-sided adhesive sheet of this example was produced in the same manner as in example 1, except that the obtained adhesive composition was used.

< example 4 >

A pressure-sensitive adhesive composition of this example was prepared in the same manner as in example 1 except that the content of the carbon black particles was changed to 5 parts per 100 parts of the acrylic polymer without using an infrared absorber, and a base-material-free double-sided pressure-sensitive adhesive sheet of this example was produced using the pressure-sensitive adhesive composition.

< example 5 >

A base material-free double-sided adhesive sheet of this example was produced in the same manner as in example 2, except that an infrared absorber was not used.

< examples 6 to 7 >

To the acrylic polymer solution prepared in example 1, 20 parts of the tackifying resin, 3 parts of the isocyanate-based crosslinking agent as a crosslinking agent, and 0.02 part of the epoxy-based crosslinking agent, and 5 parts (example 6) or 40 parts (example 7) of the cesium-containing tungsten composite oxide fine particles were added on a solid content basis with respect to 100 parts of the acrylic polymer contained in the solution, and stirred and mixed, thereby preparing each adhesive composition. A substrate-free double-sided adhesive sheet of each example was produced in the same manner as in example 1, except that the adhesive composition was used.

The results of evaluation of the adhesive in each example, the minimum value (Min) and the maximum value (Max) of the transmittance (visible light transmittance) [% ] in the wavelength range of 380nm to 550nm, the minimum value (Min) and the maximum value (Max) of the transmittance (infrared light transmittance) [% ] in the wavelength range of 800nm to 1500nm, the adhesive strength [ N/25mm ], the shear adhesion [ MPa ], the adherend masking property and the infrared blocking property are shown in Table 1. Fig. 4 shows the transmittance [% ] of light rays in the wavelength range of 380nm to 550nm of the pressure-sensitive adhesive sheet of each example.

TABLE 1

As shown in table 1, the adhesive sheets of examples 1 to 3 having a visible light transmittance of 20% or less and an infrared light transmittance of 5% or less were satisfactory in terms of both the object masking property and the infrared blocking property. On the other hand, in examples 4 to 6 having an infrared transmittance of more than 5%, the evaluation results of the infrared blocking properties were not acceptable. In example 4 in which the amount of the black coloring agent was increased to reduce the visible light transmittance to 0.3% to 0.6%, the maximum value of the infrared transmittance was more than 5%. In examples 6 to 7, the visible light transmittance was more than 20%, and the adherend masking property could not be obtained. In example 7 in which the amount of the infrared absorber was increased, the infrared transmittance was reduced to 5% or less, but the visible light transmittance was not reduced to 20% or less, and the adhesive force was also confirmed to be liable to be reduced.

From the above results, it was found that the pressure-sensitive adhesive sheet, which has a light transmittance of 20% or less in the wavelength range of 380nm to 550nm and a light transmittance of 5% or less in the wavelength range of 800nm to 1500nm, can mask an adherend and can block infrared rays.

Specific examples of the present invention have been described in detail hereinabove, but these examples are merely illustrative and do not limit the claims. The technology described in the claims includes what is obtained by variously changing the specific examples illustrated above.

Description of the reference numerals

1. 230 adhesive sheet

1A adhesive side, first adhesive side

1B adhesive side, second adhesive side

21. Adhesive layer

21A adhesive side, first adhesive side

21B adhesive side, second adhesive side

31. 32 release liner

41. First component

42. Second component

50. Laminate body

100. Portable electronic device

200. Display device

220. Display unit

240. Support part

Claims

1. An adhesive sheet having an adhesive layer, wherein,

2. The adhesive sheet according to claim 1, wherein the adhesive layer contains an infrared ray absorber and a colorant different from the infrared ray absorber.

3. The adhesive sheet according to claim 2, wherein the infrared ray absorber is a metal compound.

4. The adhesive sheet according to any one of claims 1 to 3, wherein the adhesive layer contains at least one selected from tungsten composite oxide and tin composite oxide as an infrared absorber.

5. The adhesive sheet according to any one of claims 1 to 4, wherein the adhesive layer contains a black colorant as a colorant.

6. The adhesive sheet according to claim 5, wherein the adhesive layer further comprises a metal oxide as a colorant.

7. The adhesive sheet according to any one of claims 1 to 6, wherein the total amount of the infrared absorber and the colorant contained in the adhesive layer is in the range of 5 to 30 parts by weight relative to 100 parts by weight of the base polymer contained in the adhesive layer.

8. The adhesive sheet according to any one of claims 1 to 7, wherein the adhesive layer is an acrylic adhesive layer containing an acrylic polymer as a base polymer.

9. The adhesive sheet according to any one of claims 1 to 8, wherein the thickness of the adhesive layer is in the range of 10 μm to 50 μm.

10. The adhesive sheet according to any one of claims 1 to 9, wherein the adhesive sheet is a substrate-free double-sided adhesive sheet composed of the adhesive layer.

11. The adhesive sheet according to any one of claims 1 to 10, wherein the adhesive sheet has a 180 degree peel strength to a stainless steel plate of 10N/25mm or more as measured based on JIS Z0237.

12. The adhesive sheet according to any one of claims 1 to 11, wherein the adhesive sheet is used for fixing a member of a portable electronic device.

13. A display device includes a display portion including a cover member and an organic EL unit, and a support portion, wherein,

an adhesive sheet is adhered to the supporting portion,

the adhesive sheet has an adhesive layer and,

14. A laminate having a metal member and an adhesive sheet adhered to a surface of the metal member, wherein,

the adhesive sheet has an adhesive layer and,

15. A laminate having an adhesive sheet and a member having light transmittance, wherein,

one surface of the adhesive sheet is adhered to the light-transmitting member,

the adhesive sheet has an adhesive layer and,