Adhesive sheets and displays

Abstract

To provide an adhesive sheet capable of improving the design of a display body, and a display body having improved design. [Solution] An adhesive sheet 1 having an adhesive layer 11 for bonding one display component 21 and another display component 22 together over the entire surface of a display body 2, wherein the display body 2 has a frame material 4, the frame material 4 having a lightness L* of 5 to 90, a chromaticity a* of -40 to 40, and a chromaticity b* of -40 to 40 as defined by the CIE1976 L*a*b* color system, the adhesive layer 11 being made of an adhesive containing a colorant, the colorant being a dark or deep color, the adhesive layer 11 having a total light transmittance of 3% or more, and the adhesive layer 11 having a lightness L* of 95 or less as defined by the CIE1976 L*a*b* color system.

Description

[Technical Field]

[0001] The present invention relates to an adhesive sheet used for bonding display component members, and a display using the adhesive sheet. [Background technology]

[0002] In recent years, liquid crystal display devices have been increasingly used in displays (displays), such as in-vehicle displays in automobile instrument panels, car navigation systems, various instruments mounted on consoles, displays such as tablet terminals for general users, displays such as commercial tablet terminals and digital signage, and displays such as outdoor digital signage.

[0003] As described above, in displays such as those mounted on vehicles, it is sometimes required to improve the design by creating a sense of unity with the surrounding components of the display, such as the frame material, when the display is turned off. To achieve this, it is conceivable to color the display, and for example, Patent Documents 1 to 4 disclose inventions relating to coloring of display bodies. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-313871 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-188298 [Patent Document 3] Japanese Patent Application Laid-Open No. 2012-234028 [Patent Document 4] Japanese Patent Application Laid-Open No. 2017-57375 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the techniques disclosed in the above Patent Documents 1 to 4 all have different purposes for coloring, and therefore have not been able to give the display body a sense of unity with the surrounding components and improve the design.

[0006] The present invention has been made in consideration of the above-described circumstances, and aims to provide an adhesive sheet that can improve the design of a display, and a display with improved design. [Means for solving the problem]

[0007] In order to achieve the above object, first, the present invention provides an adhesive sheet having an adhesive layer for bonding one display component to another display component, characterized in that the adhesive layer is made of an adhesive containing a colorant, the adhesive layer has a total light transmittance of 3% or more, and the lightness L* of the adhesive layer defined by the CIE1976 L*a*b* color system is 95 or less (Invention 1).

[0008] According to the above invention (Invention 1), when applied to a display, the design of the display (for example, the harmony of the appearance) can be improved when the display is turned off. In addition, since the total light transmittance is 3% or more, the visibility of the display can be ensured.

[0009] In the above invention (invention 1), the haze value of the pressure-sensitive adhesive layer is preferably 80% or less (invention 2).

[0010] In the above inventions (Inventions 1 and 2), the colorant is preferably a black pigment or dye (Invention 3).

[0011] In the above inventions (Inventions 1 to 3), when the content of the colorant in the adhesive is X mass % and the thickness of the adhesive layer is Z μm, it is preferable that the following formula (I) is satisfied (Invention 4). 5≦X×Z<250 (I)

[0012] In the above inventions (Inventions 1 to 4), the pressure-sensitive adhesive is preferably an acrylic pressure-sensitive adhesive (Invention 5).

[0013] In the above inventions (Inventions 1 to 5), it is preferable that the pressure-sensitive adhesive is a crosslinked pressure-sensitive adhesive composition containing a (meth)acrylic acid ester polymer (A), a crosslinking agent (B), and a colorant (C) (Invention 6).

[0014] In the above inventions (Inventions 1 to 6), it is preferable to have two release sheets and the pressure-sensitive adhesive layer sandwiched between the release sheets so as to be in contact with the release surfaces of the two release sheets (Invention 7).

[0015] Secondly, the present invention provides a display comprising one display component, another display component, and an adhesive layer for bonding the one display component and the other display component to each other, wherein the adhesive layer is the adhesive layer of the adhesive sheet (Inventions 1 to 7) (Invention 8).

[0016] In the above invention (Invention 8), it is preferable that at least one of the one display member constituting member and the other display member constituting member has a step at least on the surface on the side to be bonded by the pressure-sensitive adhesive layer (Invention 9).

[0017] In the above inventions (Inventions 8 and 9), it is preferable to have a black frame material (Invention 10). [Effects of the Invention]

[0018] The pressure-sensitive adhesive sheet according to the present invention can improve the design of the display body. Furthermore, the display body according to the present invention has improved design. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a cross-sectional view of a pressure-sensitive adhesive sheet according to one embodiment of the present invention. [Figure 2] 1 is a cross-sectional view of a display according to an embodiment of the present invention. [Figure 3] 1 is a plan view of a display having a frame material according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, an embodiment of the present invention will be described. [Adhesive sheet] The pressure-sensitive adhesive sheet according to one embodiment of the present invention includes a pressure-sensitive adhesive layer for bonding one display component to another, and preferably includes a release sheet laminated on one or both sides of the pressure-sensitive adhesive layer. The display and the display component will be described later.

[0021] FIG. 1 shows a specific configuration of an example of the pressure-sensitive adhesive sheet according to this embodiment. 1, the adhesive sheet 1 is composed of two release sheets 12a and 12b and an adhesive layer 11 sandwiched between the two release sheets 12a and 12b so as to be in contact with the release surfaces of the two release sheets 12a and 12b. In this specification, the release surface of a release sheet refers to the surface of the release sheet that has releasability, and includes both a surface that has been subjected to a release treatment and a surface that exhibits releasability even without being subjected to a release treatment.

[0022] 1. Each component 1-1. Adhesive layer The pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1 according to this embodiment is made of a pressure-sensitive adhesive containing a colorant. The pressure-sensitive adhesive layer 11 has a total light transmittance (measured in accordance with JIS K7361-1:1997) of 3% or more, and a lightness L* of the pressure-sensitive adhesive layer 11 defined by the CIE 1976 L*a*b* color system of 95 or less. The method for measuring lightness L* in this specification is as shown in the test examples described below.

[0023] When the pressure-sensitive adhesive layer 11 having the above physical properties is applied to a display, it can improve the design (for example, the appearance harmony) of the display when the display is turned off. Specifically, it can give the display a sense of unity with surrounding components, such as a black frame material, thereby giving it a luxurious feel. Furthermore, by having a total light transmittance of 3% or more, it can ensure visibility as a display.

[0024] Specific examples of the peripheral components include automobile dashboards having a lightness L* of 23.2, a chromaticity a* of -0.5, and a chromaticity b* of -1.5 as defined by the CIE 1976 L*a*b* color system. The color of the peripheral component is preferably a lightness L* of 5 to 90, a chromaticity a* of -40 to 40, and a chromaticity b* of -40 to 40, more preferably a lightness L* of 10 to 80, a chromaticity a* of -30 to 30, and a chromaticity b* of -30 to 30, and even more preferably a lightness L* of 15 to 70, a chromaticity a* of -20 to 20, and a chromaticity b* of -20 to 20. The pressure-sensitive adhesive sheet 1 according to this embodiment can be suitably used for displays having peripheral components with the above colors.

[0025] From the above viewpoints, the total light transmittance of the pressure-sensitive adhesive layer 11 is 3% or more, preferably 5% or more, and particularly preferably 8% or more. The upper limit of the total light transmittance is not particularly limited, but is usually 100% or less, and in consideration of the relationship with the above-mentioned lightness L*, it is preferably 98% or less, particularly preferably 95% or less, and further preferably 93% or less.

[0026] From the viewpoint of improving the design, the lightness L* of the pressure-sensitive adhesive layer 11 is not more than 95, preferably not more than 90, particularly preferably not more than 85, and even more preferably not more than 75. On the other hand, from the viewpoint of improving the design and the visibility of the display, the lower limit of the lightness L* is preferably not less than 10, particularly preferably not less than 20, and even more preferably not less than 25.

[0027] Furthermore, the chromaticity a* of the pressure-sensitive adhesive layer 11, as defined by the CIE 1976 L*a*b* color system, is preferably -40 or more, more preferably -30 or more, particularly preferably -20 or more, further preferably -15 or more, and most preferably -10 or more. The chromaticity a* is preferably 40 or less, more preferably 30 or less, particularly preferably 20 or less, further preferably 15 or less, and most preferably 10 or less. Having the chromaticity a* in the above range further improves the design, particularly the design of an in-vehicle display.

[0028] The chromaticity b* of the pressure-sensitive adhesive layer 11, as defined by the CIE 1976 L*a*b* color system, is preferably −40 or more, more preferably −30 or more, particularly preferably −20 or more, further preferably −15 or more, and most preferably −10 or more. The chromaticity b* is preferably 40 or less, more preferably 30 or less, particularly preferably 20 or less, further preferably 15 or less, and most preferably 10 or less. Having the chromaticity b* in the above range further improves the design, particularly the design of an in-vehicle display.

[0029] The haze value of the pressure-sensitive adhesive layer 11 is preferably 80% or less, particularly preferably 75% or less, and even more preferably 70% or less. By setting the upper limit of the haze value of the pressure-sensitive adhesive layer 11 within the above range, the total light transmittance is likely to fall within the above range, and the resulting display body is more likely to be integrated with surrounding components (e.g., frame materials). Meanwhile, the haze value of the pressure-sensitive adhesive layer 11 is typically 0% or more. When the colorant in the pressure-sensitive adhesive layer 11 is a dye, it is preferably 0.01% or more, particularly preferably 0.1% or more. When the colorant in the pressure-sensitive adhesive layer 11 is a pigment, the haze value of the pressure-sensitive adhesive layer 11 is preferably 3% or more, more preferably 10% or more, and particularly preferably 25% or more. When the lower limit of the haze value of the pressure-sensitive adhesive layer 11 is within the above range, the resulting display body is more likely to be integrated with surrounding components (e.g., frame materials). The haze value in this specification is a value measured in accordance with JIS K7136:2000.

[0030] The above-mentioned total light transmittance and brightness L* (as well as chromaticity a* and b*, and haze value) can be achieved by appropriately selecting the type and content of the colorant contained in the adhesive constituting the adhesive layer 11.

[0031] The colorant may be a pigment or a dye. The pigment may be an inorganic pigment or an organic pigment. From the viewpoint of the durability of the resulting adhesive, inorganic pigments are preferred. The color of the colorant can be appropriately selected according to the color of the surrounding components to which a sense of unity is desired, but generally, a dark or deep color such as black, brown, navy blue, purple, or blue is preferred, and black is particularly preferred.

[0032] Examples of inorganic pigments include carbon black, cobalt-based pigments, iron-based pigments, chromium-based pigments, titanium-based pigments, vanadium-based pigments, zirconium-based pigments, molybdenum-based pigments, ruthenium-based pigments, platinum-based pigments, ITO (indium tin oxide)-based pigments, and ATO (antimony tin oxide)-based pigments.

[0033] Examples of organic pigments and organic dyes include aminium-based dyes, cyanine-based dyes, merocyanine-based dyes, croconium-based dyes, squarium-based dyes, azulenium-based dyes, polymethine-based dyes, naphthoquinone-based dyes, pyrylium-based dyes, phthalocyanine-based dyes, naphthalocyanine-based dyes, naphtholactam-based dyes, azo-based dyes, condensed azo-based dyes, indigo-based dyes, perinone-based dyes, perylene-based dyes, dioxazine-based dyes, quinacridone-based dyes, isoindolinone-based dyes, quinophthalone-based dyes, pyrrole-based dyes, thioindigo-based dyes, metal complex-based dyes (metal complex dyes), dithiol metal complex-based dyes, indolephenol-based dyes, triallylmethane-based dyes, anthraquinone-based dyes, dioxazine-based dyes, naphthol-based dyes, azomethine-based dyes, benzimidazolone-based dyes, pyranthrone-based dyes, and threne-based dyes.

[0034] Examples of black pigments include carbon black, copper oxide, iron oxide, manganese dioxide, aniline black, activated carbon, etc. Examples of black dyes include high-concentration vegetable dyes and azo dyes.

[0035] The above pigments or dyes can be mixed appropriately so that the desired physical properties of the adhesive layer 11 can be obtained.

[0036] Among the above colorants, carbon black, nigrosine-based black dyes, and chromate-based black dyes are preferred because they can easily achieve the total light transmittance and lightness L* (and also the haze value) described above and easily create a sense of unity with surrounding components. Note that the carbon black may or may not have been subjected to a predetermined surface treatment (for example, a solvent-philic treatment).

[0037] The content X mass % of the colorant in the pressure-sensitive adhesive is preferably a value that satisfies the following formula (I) when the thickness of the pressure-sensitive adhesive layer 11 is Z μm. 5≦X×Z<250 (I) When the value of X×Z is within the above range, the total light transmittance and brightness L* (and further the haze value) described above are easily achieved. Note that the thickness of the pressure-sensitive adhesive layer 11 in this specification is a value measured in accordance with JIS K7130.

[0038] From the above viewpoints, the lower limit of X×Z is preferably 7 or more, particularly preferably 10 or more, and further preferably 15 or more. The upper limit of X×Z is preferably 235 or less, particularly preferably 220 or less, and further preferably 200 or less.

[0039] To make it easier for the value of X×Z to fall within the above range, the content of the colorant in the adhesive (X% by mass) is preferably 0.01% by mass or more as a lower limit, particularly preferably 0.05% by mass or more, and even more preferably 0.10% by mass or more as an upper limit, and preferably 10% by mass or less as an upper limit, particularly preferably 7% by mass or less, and even more preferably 4% by mass or less as an upper limit.

[0040] The type of adhesive constituting the adhesive layer 11 of the adhesive sheet 1 according to this embodiment is not particularly limited, and may be, for example, an acrylic adhesive, a polyester adhesive, a polyurethane adhesive, a rubber adhesive, a silicone adhesive, or the like. The adhesive may be an emulsion type, a solvent type, or a solventless type, and may be a crosslinked type or a non-crosslinked type. Among these, an acrylic adhesive is preferred because of its excellent adhesive properties, optical properties, and the like.

[0041] The acrylic adhesive may be either active energy ray-curable or non-active energy ray-curable, but from the viewpoints of durability and simplification of the manufacturing process of the display body, a non-active energy ray-curable acrylic adhesive is preferred. As the non-active energy ray-curable acrylic adhesive, a crosslinked type is particularly preferred, and a thermal crosslinked type is more preferred.

[0042] The above-mentioned adhesive is preferably obtained by crosslinking an adhesive composition (hereinafter sometimes referred to as "adhesive composition P") containing a (meth)acrylic acid ester polymer (A), a crosslinking agent (B), and a colorant (C). The colorant (C) is the colorant described above. An adhesive obtained from such adhesive composition P can exhibit excellent optical properties, adhesive strength, durability (adjustability to conform to uneven surfaces under high temperature and high humidity conditions), etc. In this specification, (meth)acrylic acid means both acrylic acid and methacrylic acid. The same applies to other similar terms. Furthermore, the term "polymer" also includes the concept of "copolymer."

[0043] (1) Components of the adhesive composition (1-1) (Meth)acrylic acid ester polymer (A) The (meth)acrylic acid ester polymer (A) in this embodiment preferably contains, as a monomer unit constituting the polymer, a reactive group-containing monomer having in the molecule a reactive group that reacts with the crosslinking agent (B). The reactive group derived from this reactive group-containing monomer reacts with the crosslinking agent (B) to form a crosslinked structure (three-dimensional network structure), thereby obtaining a pressure-sensitive adhesive having the desired cohesive strength.

[0044] Preferred examples of the reactive group-containing monomer include a monomer having a hydroxyl group in the molecule (hydroxyl group-containing monomer), a monomer having a carboxyl group in the molecule (carboxyl group-containing monomer), a monomer having an amino group in the molecule (amino group-containing monomer), etc. Among these, hydroxyl group-containing monomers and carboxyl group-containing monomers that have excellent reactivity with the crosslinking agent (B) are preferred, and hydroxyl group-containing monomers that have little adverse effect on the adherend are particularly preferred.

[0045] Examples of hydroxyl group-containing monomers include (meth)acrylic acid hydroxyalkyl esters such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. Among these, 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are preferred, with 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate being particularly preferred, from the standpoint of the reactivity of the hydroxyl groups in the resulting (meth)acrylic acid ester polymer (A) with the crosslinking agent (B) and copolymerizability with other monomers. These may be used alone or in combination of two or more.

[0046] Examples of carboxyl group-containing monomers include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. Among these, acrylic acid is preferred in terms of the reactivity of the carboxyl group in the resulting (meth)acrylic acid ester polymer (A) with the crosslinking agent (B) and copolymerizability with other monomers. These may be used alone or in combination of two or more.

[0047] Examples of the amino group-containing monomer include aminoethyl (meth)acrylate, n-butylaminoethyl (meth)acrylate, etc. These may be used alone or in combination of two or more.

[0048] The (meth)acrylic acid ester polymer (A) preferably contains a reactive group-containing monomer as a monomer unit constituting the polymer in an amount of at least 1 mass%, particularly preferably at least 5 mass%, and even more preferably at least 10 mass%. When the reactive group-containing monomer is a hydroxyl group-containing monomer, it is particularly preferred that the reactive group-containing monomer be at least 15 mass%. The (meth)acrylic acid ester polymer (A) preferably contains a reactive group-containing monomer as a monomer unit constituting the polymer in an amount of at most 35 mass%, particularly preferably at most 30 mass%, and even more preferably at most 25 mass%. When the (meth)acrylic acid ester polymer (A) contains the reactive group-containing monomer as a monomer unit in the above amount, a good crosslinked structure is formed in the resulting pressure-sensitive adhesive, and the desired cohesive strength is achieved. Furthermore, the dispersibility of the colorant (C) in the adhesive tends to be improved, and the resulting adhesive exhibits good reproducibility and uniformity in total light transmittance and lightness L* (as well as chromaticity a* and b*, and haze value), resulting in excellent appearance harmony and character visibility. Furthermore, when the reactive group-containing monomer is a hydroxyl group-containing monomer, a content of 15% by mass or more results in a predetermined amount of hydroxyl groups remaining in the adhesive. Hydroxyl groups are hydrophilic groups, and the presence of a predetermined amount of such hydrophilic groups in the adhesive provides good compatibility with moisture that penetrates the adhesive under high-temperature, high-humidity conditions, even when the adhesive is placed under these conditions. As a result, whitening of the adhesive when returned to room temperature and humidity is suppressed (excellent resistance to humidity-heat whitening).

[0049] It is also preferable that the (meth)acrylic acid ester polymer (A) does not contain a carboxyl group-containing monomer as a monomer unit constituting the polymer. Because a carboxyl group is an acid component, the absence of a carboxyl group-containing monomer can prevent acid-induced defects (corrosion, resistance change, etc.) even when the target to which the pressure-sensitive adhesive is applied contains a material that may be affected by acid, such as a transparent conductive film such as tin-doped indium oxide (ITO) or a metal film. However, it is acceptable to contain a predetermined amount of a carboxyl group-containing monomer to the extent that such defects do not occur. Specifically, it is acceptable for the (meth)acrylic acid ester polymer (A) to contain, as a monomer unit, a carboxyl group-containing monomer in an amount of 0.1% by mass or less, preferably 0.01% by mass or less, and more preferably 0.001% by mass or less.

[0050] The (meth)acrylic acid ester polymer (A) preferably contains a (meth)acrylic acid alkyl ester as a monomer unit constituting the polymer. This allows the polymer to exhibit good adhesiveness. The alkyl group may be linear or branched.

[0051] From the viewpoint of adhesiveness, the (meth)acrylic acid alkyl ester is preferably a (meth)acrylic acid alkyl ester in which the alkyl group has 1 to 20 carbon atoms. Examples of the (meth)acrylic acid alkyl ester in which the alkyl group has 1 to 20 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate, myristyl (meth)acrylate, palmityl (meth)acrylate, and stearyl (meth)acrylate. Among these, from the viewpoint of further improving adhesiveness, (meth)acrylic acid esters having an alkyl group carbon number of 1 to 8 are preferred, methyl (meth)acrylate, n-butyl (meth)acrylate, or 2-ethylhexyl (meth)acrylate are particularly preferred, and methyl methacrylate, n-butyl acrylate, or 2-ethylhexyl acrylate are even more preferred. These may be used alone or in combination of two or more.

[0052] The (meth)acrylic acid ester polymer (A) preferably contains 50% by mass or more, particularly preferably 60% by mass or more, and even more preferably 65% ​​by mass or more, of (meth)acrylic acid alkyl ester as a monomer unit constituting the polymer. When the lower limit of the (meth)acrylic acid alkyl ester content is as described above, the (meth)acrylic acid ester polymer (A) can exhibit suitable adhesive properties. Furthermore, the (meth)acrylic acid ester polymer (A) preferably contains 99% by mass or less, particularly preferably 95% by mass or less, and even more preferably 90% by mass or less, of (meth)acrylic acid alkyl ester as a monomer unit constituting the polymer. When the upper limit of the (meth)acrylic acid alkyl ester content is as described above, suitable amounts of other monomer components, such as reactive functional group-containing monomers, can be incorporated into the (meth)acrylic acid ester polymer (A).

[0053] The (meth)acrylic acid ester polymer (A) preferably contains a monomer having an alicyclic structure in the molecule (alicyclic structure-containing monomer) as a monomer unit constituting the polymer. Because the alicyclic structure-containing monomer is bulky, its presence in the polymer is presumed to increase the spacing between polymer molecules, thereby making the resulting pressure-sensitive adhesive excellent in flexibility. This allows the pressure-sensitive adhesive to have excellent conformability to uneven surfaces.

[0054] The carbon ring of the alicyclic structure in the alicyclic structure-containing monomer may be a saturated structure or may partially contain an unsaturated bond. The alicyclic structure may be a monocyclic alicyclic structure or a polycyclic alicyclic structure such as a bicyclic or tricyclic structure. From the viewpoint of optimizing the distance between the rings in the resulting (meth)acrylic acid ester polymer (A) and imparting high stress relaxation properties to the adhesive, the alicyclic structure is preferably a polycyclic alicyclic structure (a polycyclic structure). Furthermore, in consideration of the compatibility of the (meth)acrylic acid ester polymer (A) with other components, the polycyclic structure is particularly preferably a bicyclic to tetracyclic structure. Similarly, from the viewpoint of imparting stress relaxation properties, the number of carbon atoms in the alicyclic structure (meaning the total number of carbon atoms in the ring, or the total number of carbon atoms in the case of multiple independent rings) is preferably 5 or more, and particularly preferably 7 or more. On the other hand, there is no particular upper limit on the number of carbon atoms in the alicyclic structure, but from the viewpoint of compatibility as described above, it is preferably 15 or less, and particularly preferably 10 or less.

[0055] Specific examples of the alicyclic structure-containing monomer include cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, adamantyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, and dicyclopentenyloxyethyl (meth)acrylate. Among these, dicyclopentanyl (meth)acrylate (alicyclic structure carbon number: 10), adamantyl (meth)acrylate (alicyclic structure carbon number: 10), or isobornyl (meth)acrylate (alicyclic structure carbon number: 7) are preferred, as they exhibit superior conformability to uneven surfaces. Isobornyl (meth)acrylate is particularly preferred, and isobornyl acrylate is even more preferred. These may be used alone or in combination of two or more.

[0056] When the (meth)acrylic acid ester polymer (A) contains an alicyclic structure-containing monomer as a monomer unit constituting the polymer, it preferably contains the alicyclic structure-containing monomer in an amount of 1% by mass or more, particularly preferably 4% by mass or more, and even more preferably 8% by mass or more. Furthermore, the (meth)acrylic acid ester polymer (A) preferably contains the alicyclic structure-containing monomer as a monomer unit constituting the polymer in an amount of 30% by mass or less, particularly preferably 22% by mass or less, and even more preferably 14% by mass or less. By having the alicyclic structure-containing monomer content within the above range, the resulting pressure-sensitive adhesive has better conformability to uneven surfaces and better adhesion to plastics.

[0057] The (meth)acrylic acid ester polymer (A) also preferably contains a nitrogen-atom-containing monomer as a monomer unit constituting the polymer. The presence of a nitrogen-atom-containing monomer as a constituent unit in the polymer imparts a predetermined polarity to the PSA, making it possible to provide excellent affinity for adherends with a certain degree of polarity, such as glass. The nitrogen-atom-containing monomer is preferably a monomer having a nitrogen-containing heterocycle, from the viewpoint of providing the (meth)acrylic acid ester polymer (A) with appropriate rigidity. Furthermore, from the viewpoint of increasing the degree of freedom of the portion derived from the nitrogen-atom-containing monomer in the higher-order structure of the PSA formed, it is preferable that the nitrogen-atom-containing monomer does not contain a reactive unsaturated double bond group other than the one polymerizable group used in polymerization to form the (meth)acrylic acid ester polymer (A).

[0058] Examples of monomers having a nitrogen-containing heterocycle include N-(meth)acryloylmorpholine, N-vinyl-2-pyrrolidone, N-(meth)acryloylpyrrolidone, N-(meth)acryloylpiperidine, N-(meth)acryloylpyrrolidine, N-(meth)acryloylaziridine, aziridinylethyl (meth)acrylate, 2-vinylpyridine, 4-vinylpyridine, 2-vinylpyrazine, 1-vinylimidazole, N-vinylcarbazole, and N-vinylphthalimide. Among these, N-(meth)acryloylmorpholine, which exhibits superior adhesive strength, is preferred, and N-acryloylmorpholine is particularly preferred. These may be used alone or in combination of two or more.

[0059] When the (meth)acrylic acid ester polymer (A) contains a nitrogen atom-containing monomer as a monomer unit constituting the polymer, it preferably contains the nitrogen atom-containing monomer in an amount of 1% by mass or more, particularly preferably 4% by mass or more, and even more preferably 8% by mass or more. Furthermore, the (meth)acrylic acid ester polymer (A) preferably contains the nitrogen atom-containing monomer as a monomer unit constituting the polymer in an amount of 20% by mass or less, particularly preferably 16% by mass or less, and even more preferably 12% by mass or less. When the nitrogen atom-containing monomer content is within the above range, the resulting pressure-sensitive adhesive can fully exhibit excellent adhesive strength to glass.

[0060] The (meth)acrylic acid ester polymer (A) may contain other monomers as monomer units constituting the polymer, if desired. The other monomers are preferably monomers that do not contain reactive functional groups, so as not to inhibit the aforementioned action of the reactive functional group-containing monomer. Examples of such monomers include (meth)acrylic acid alkoxyalkyl esters such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate, vinyl acetate, and styrene. These may be used alone or in combination of two or more.

[0061] The (meth)acrylic acid ester polymer (A) is preferably a linear polymer, which facilitates entanglement of molecular chains and is expected to improve cohesive strength, making it easier to obtain a pressure-sensitive adhesive with excellent step-following ability under high-temperature, high-humidity conditions.

[0062] The (meth)acrylic acid ester polymer (A) is preferably a solution polymer obtained by solution polymerization. By using a solution polymer, a high molecular weight polymer can be easily obtained, and an improved cohesive strength can be expected, so that a pressure-sensitive adhesive having excellent step-following ability under high-temperature and high-humidity conditions can be easily obtained.

[0063] The polymerization mode of the (meth)acrylic acid ester polymer (A) may be a random copolymer or a block copolymer.

[0064] The weight average molecular weight of the (meth)acrylic acid ester polymer (A) preferably has a lower limit of 200,000 or more, particularly preferably 300,000 or more, and even more preferably 400,000 or more. When the lower limit of the weight average molecular weight of the (meth)acrylic acid ester polymer (A) is above the above limit, the resulting pressure-sensitive adhesive has better conformability to unevenness under high-temperature and high-humidity conditions.

[0065] The upper limit of the weight-average molecular weight of the (meth)acrylic acid ester polymer (A) is preferably 2,000,000 or less, particularly preferably 1,500,000 or less, and even more preferably 1,000,000 or less. When the upper limit of the weight-average molecular weight of the (meth)acrylic acid ester polymer (A) is not more than the above range, the resulting pressure-sensitive adhesive has better conformability to uneven surfaces. Note that the weight-average molecular weight in this specification is a value measured by gel permeation chromatography (GPC) in terms of standard polystyrene.

[0066] In the pressure-sensitive adhesive composition P, the (meth)acrylic acid ester polymer (A) may be used singly or in combination of two or more kinds.

[0067] (1-2) Crosslinking agent (B) The crosslinking agent (B) crosslinks the (meth)acrylic acid ester polymer (A) by heating the pressure-sensitive adhesive composition P, enabling the formation of a favorable three-dimensional network structure. This improves the cohesive strength of the resulting pressure-sensitive adhesive, and provides it with excellent step-following ability under high-temperature, high-humidity conditions.

[0068] The crosslinking agent (B) may be any agent that reacts with the reactive groups of the (meth)acrylic acid ester polymer (A). Examples of the crosslinking agent (B) include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, amine-based crosslinking agents, melamine-based crosslinking agents, aziridine-based crosslinking agents, hydrazine-based crosslinking agents, aldehyde-based crosslinking agents, oxazoline-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, and ammonium salt-based crosslinking agents. Among these, when the reactive group of the (meth)acrylic acid ester polymer (A) is a hydroxyl group, it is preferable to use an isocyanate-based crosslinking agent that has excellent reactivity with the hydroxyl group. When the reactive group of the (meth)acrylic acid ester polymer (A) is a carboxyl group, it is preferable to use an epoxy-based crosslinking agent that has excellent reactivity with the carboxyl group. The crosslinking agent (B) may be used alone or in combination of two or more.

[0069] The isocyanate-based crosslinking agent contains at least a polyisocyanate compound. Examples of polyisocyanate compounds include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate; alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate; and biuret and isocyanurate forms thereof, as well as adducts thereof that are reaction products with low-molecular-weight active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil. Among these, trimethylolpropane-modified aromatic polyisocyanates, particularly trimethylolpropane-modified tolylene diisocyanate and trimethylolpropane-modified xylylene diisocyanate, are preferred from the viewpoint of reactivity with hydroxyl groups.

[0070] Examples of epoxy crosslinking agents include 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-m-xylylenediamine, ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidylaniline, diglycidylamine, etc. Among these, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane is preferred from the viewpoint of reactivity with carboxy groups.

[0071] The content of the crosslinking agent (B) in the pressure-sensitive adhesive composition P is preferably 0.01 parts by mass or more, particularly preferably 0.03 parts by mass or more, and even more preferably 0.05 parts by mass or more, relative to 100 parts by mass of the (meth)acrylic acid ester polymer (A). The content is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, particularly preferably 1 part by mass or less, and even more preferably 0.4 parts by mass or less. By having the content of the crosslinking agent (B) within the above range, the resulting pressure-sensitive adhesive exhibits good cohesion and exhibits excellent step-following ability under high-temperature and high-humidity conditions.

[0072] (1-3) Colorant (C) The colorant (C) is the colorant described above. The specific type and content are as described above.

[0073] (1-4) Various additives If desired, various additives commonly used in acrylic pressure-sensitive adhesives, such as a silane coupling agent, an anti-rust agent, an ultraviolet absorber, an antistatic agent, a tackifier, an antioxidant, a light stabilizer, a softener, a refractive index adjuster, etc., can be added to the pressure-sensitive adhesive composition P. The polymerization solvent and dilution solvent described below are not included in the additives constituting the pressure-sensitive adhesive composition P.

[0074] Among the above, the pressure-sensitive adhesive composition P preferably contains a silane coupling agent, which improves adhesion to the adherend, whether the adherend is a plastic plate or a glass member, and provides better conformability to uneven surfaces under high-temperature and high-humidity conditions.

[0075] The silane coupling agent is preferably an organosilicon compound having at least one alkoxysilyl group in the molecule, which has good compatibility with the (meth)acrylic acid ester polymer (A) and has optical transparency.

[0076] Examples of such silane coupling agents include polymerizable unsaturated group-containing silicon compounds such as vinyltrimethoxysilane, vinyltriethoxysilane, and methacryloxypropyltrimethoxysilane; epoxy structure-containing silicon compounds such as 3-glycidoxypropyltrimethoxysilane and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; and mercapto group-containing silicon compounds such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, and 3-mercaptopropyldimethoxymethylsilane. , 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, and other amino group-containing silicon compounds, 3-chloropropyltrimethoxysilane, 3-isocyanatepropyltriethoxysilane, and condensates of at least one of these with alkyl group-containing silicon compounds such as methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, and ethyltrimethoxysilane. These may be used alone or in combination of two or more.

[0077] The content of the silane coupling agent in the pressure-sensitive adhesive composition P is preferably 0.01 parts by mass or more, particularly preferably 0.05 parts by mass or more, and even more preferably 0.1 parts by mass or more, relative to 100 parts by mass of the (meth)acrylic acid ester polymer (A). The content is also preferably 1 part by mass or less, particularly preferably 0.5 parts by mass or less, and even more preferably 0.3 parts by mass or less.

[0078] The adhesive composition P also preferably contains a rust inhibitor. Examples of rust inhibitors include azole compounds, triazole compounds, benzotriazole compounds, thiazole compounds, benzothiazole compounds, imidazole compounds, benzimidazole compounds, phosphorus compounds, amine compounds, nitrite compounds, surfactants, and silane coupling agents, among which benzotriazole compounds are preferred. When a benzotriazole compound is used, it has a high rust prevention effect on metals and is highly compatible with the adhesive.

[0079] The content of the rust inhibitor in the pressure-sensitive adhesive composition P is preferably 0.01 parts by mass or more, particularly preferably 0.05 parts by mass or more, and even more preferably 0.1 parts by mass or more, relative to 100 parts by mass of the (meth)acrylic acid ester polymer (A). The content is also preferably 3 parts by mass or less, particularly preferably 1 part by mass or less, and even more preferably 0.5 parts by mass or less.

[0080] (2) Preparation of adhesive composition The adhesive composition P can be produced by producing a (meth)acrylic acid ester polymer (A), mixing the resulting (meth)acrylic acid ester polymer (A) with a crosslinking agent (B) and a colorant (C), and adding additives as desired.

[0081] The (meth)acrylic acid ester polymer (A) can be produced by polymerizing a mixture of monomers constituting the polymer by a conventional radical polymerization method. The polymerization of the (meth)acrylic acid ester polymer (A) is preferably carried out by a solution polymerization method, using a polymerization initiator as desired. Examples of polymerization solvents include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, and methyl ethyl ketone, and two or more of them may be used in combination.

[0082] Examples of the polymerization initiator include azo compounds and organic peroxides, and two or more of them may be used in combination. Examples of the azo compounds include 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile), dimethyl 2,2'-azobis(2-methylpropionate), 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(2-hydroxymethylpropionitrile), and 2,2'-azobis[2-(2-imidazolin-2-yl)propane].

[0083] Examples of organic peroxides include benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di(2-ethoxyethyl)peroxydicarbonate, t-butyl peroxyneodecanoate, t-butyl peroxypivalate, (3,5,5-trimethylhexanoyl)peroxide, dipropionyl peroxide, and diacetyl peroxide.

[0084] In the polymerization step, the weight average molecular weight of the resulting polymer can be adjusted by adding a chain transfer agent such as 2-mercaptoethanol.

[0085] Once the (meth)acrylic acid ester polymer (A) is obtained, the crosslinking agent (B), the colorant (C), and optionally a dilution solvent and additives are added to the solution of the (meth)acrylic acid ester polymer (A) and mixed thoroughly to obtain a solvent-diluted pressure-sensitive adhesive composition P (coating solution). Note that when any of the above components is used in a solid state or when precipitation occurs when mixed with other components in an undiluted state, that component may be dissolved or diluted alone in a dilution solvent before being mixed with other components.

[0086] Examples of the dilution solvent include aliphatic hydrocarbons such as hexane, heptane, and cyclohexane; aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as methylene chloride and ethylene chloride; alcohols such as methanol, ethanol, propanol, butanol, and 1-methoxy-2-propanol; ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone, and cyclohexanone; esters such as ethyl acetate and butyl acetate; and cellosolve-based solvents such as ethyl cellosolve.

[0087] The concentration and viscosity of the coating solution prepared in this manner are not particularly limited as long as they are within a range that allows coating, and can be appropriately selected depending on the situation. For example, the adhesive composition P is diluted so that the concentration becomes 10 to 60 mass %. Note that the addition of a dilution solvent or the like is not a necessary condition for obtaining the coating solution, and as long as the adhesive composition P has a viscosity that allows coating, the addition of a dilution solvent is not necessary. In this case, the adhesive composition P becomes a coating solution in which the polymerization solvent for the (meth)acrylic acid ester polymer (A) itself serves as the dilution solvent.

[0088] (3) Formation of adhesive layer The adhesive layer 11 in this embodiment preferably comprises an adhesive obtained by crosslinking (a coating layer of) the adhesive composition P. The crosslinking of the adhesive composition P can usually be carried out by a heat treatment. Note that this heat treatment can also serve as a drying treatment for volatilizing diluent solvents and the like from the coating layer of the adhesive composition P applied to the desired object.

[0089] The heating temperature for the heat treatment is preferably 50 to 150° C., particularly preferably 70 to 120° C. The heating time is preferably 10 seconds to 10 minutes, particularly preferably 50 seconds to 2 minutes.

[0090] After the heat treatment, if necessary, a curing period of about 1 to 2 weeks may be provided at room temperature (e.g., 23°C, 50% RH). If this curing period is required, the adhesive will be formed after the curing period has elapsed; if no curing period is required, the adhesive will be formed after the heat treatment has been completed.

[0091] The heat treatment (and curing) allows the (meth)acrylic acid ester polymer (A) to be sufficiently crosslinked via the crosslinking agent (B), and the pressure-sensitive adhesive thus obtained exhibits excellent conformability to uneven surfaces under high-temperature and high-humidity conditions.

[0092] (4) Physical properties of adhesive The adhesive in this embodiment preferably has the following physical properties. (4-1) Gel fraction The lower limit of the gel fraction of the pressure-sensitive adhesive according to this embodiment is preferably 20% or more, more preferably 25% or more, and particularly preferably 30% or more. When the lower limit of the gel fraction of the pressure-sensitive adhesive is as described above, the cohesive strength of the pressure-sensitive adhesive is increased, resulting in better step-conforming ability under high-temperature, high-humidity conditions. Furthermore, the upper limit of the gel fraction of the pressure-sensitive adhesive according to this embodiment is preferably 95% or less, more preferably 90% or less, particularly preferably 80% or less, and even more preferably 70% or less. When the upper limit of the gel fraction of the pressure-sensitive adhesive is as described above, the pressure-sensitive adhesive does not become too hard, resulting in excellent step-conforming ability both initially and after durability testing. Furthermore, good adhesive strength is exhibited, resulting in better adhesion to the adherend. The method for measuring the gel fraction of the pressure-sensitive adhesive is as shown in the test examples described below.

[0093] (4-2) Storage modulus The storage modulus of the pressure-sensitive adhesive according to this embodiment at 23°C is preferably 0.01 MPa or more as a lower limit, particularly preferably 0.03 MPa or more, and even more preferably 0.05 MPa or more. By setting the storage modulus lower limit as described above, excellent step-conforming properties are achieved under high-temperature and high-humidity conditions. Furthermore, the storage modulus is preferably 0.5 MPa or less as an upper limit, particularly preferably 0.3 MPa or less, and even more preferably 0.2 MPa or less. By setting the storage modulus upper limit as described above, excellent initial step-conforming properties are achieved. The storage modulus in this specification is a value measured by a torsional shear method at a measurement frequency of 1 Hz in accordance with JIS K7244-6. Specific examples are as shown in the test examples described below.

[0094] (5) Thickness of adhesive layer The thickness (Z μm) of the pressure-sensitive adhesive layer 11 in the pressure-sensitive adhesive sheet 1 according to this embodiment preferably satisfies the above-mentioned formula X×Z (I).

[0095] Specifically, the thickness of the pressure-sensitive adhesive layer 11 preferably has a lower limit of 1 μm or more, more preferably 2 μm or more, and particularly preferably 4 μm or more. When the lower limit of the thickness of the pressure-sensitive adhesive layer 11 is as described above, the total light transmittance and lightness L* (and further the chromaticity a* and b*, and the haze value) described above are likely to be satisfied in relation to the content of the colorant (C), and the desired adhesive strength is likely to be exhibited. Furthermore, from the viewpoint of easily exhibiting excellent step-conforming ability, the lower limit is preferably 10 μm or more, more preferably 15 μm or more, particularly preferably 20 μm or more, and even more preferably 45 μm or more.

[0096] The upper limit of the thickness of the pressure-sensitive adhesive layer 11 is preferably 500 μm or less, more preferably 300 μm or less, particularly preferably 200 μm or less, and even more preferably 150 μm or less. When the upper limit of the thickness of the pressure-sensitive adhesive layer 11 is within the above range, processability is improved. Also, appearance defects due to indentations and the like are less likely to occur. Furthermore, in relation to the content of the colorant (C), the total light transmittance and lightness L* (as well as chromaticity a* and b*, and haze value) described above are more likely to be satisfied. The pressure-sensitive adhesive layer 11 may be formed as a single layer, or may be formed by laminating multiple layers.

[0097] 1-2.Release sheet Release sheets 12a and 12b protect adhesive layer 11 until adhesive sheet 1 is used, and are peeled off when adhesive sheet 1 (adhesive layer 11) is to be used. In adhesive sheet 1 according to this embodiment, one or both of release sheets 12a and 12b are not necessarily required.

[0098] Examples of materials that can be used as the release sheets 12a and 12b include polyethylene films, polypropylene films, polybutene films, polybutadiene films, polymethylpentene films, polyvinyl chloride films, vinyl chloride copolymer films, polyethylene terephthalate films, polyethylene naphthalate films, polybutylene terephthalate films, polyurethane films, ethylene vinyl acetate films, ionomer resin films, ethylene-(meth)acrylic acid copolymer films, ethylene-(meth)acrylic acid ester copolymer films, polystyrene films, polycarbonate films, polyimide films, and fluororesin films. Crosslinked films of these materials can also be used. Furthermore, laminated films of these materials can also be used.

[0099] The release surfaces of the release sheets 12a and 12b (particularly the surfaces in contact with the pressure-sensitive adhesive layer 11) are preferably subjected to a release treatment. Examples of release agents used for the release treatment include alkyd-based, silicone-based, fluorine-based, unsaturated polyester-based, polyolefin-based, and wax-based release agents. Preferably, one of the release sheets 12a and 12b is a heavy-release type release sheet with a high release strength, and the other is a light-release type release sheet with a low release strength.

[0100] There are no particular restrictions on the thickness of the release sheets 12a and 12b, but it is usually about 20 to 150 μm.

[0101] 2.Physical properties (adhesion) The adhesive strength of the adhesive sheet 1 according to this embodiment to soda-lime glass preferably has a lower limit of 1 N / 25 mm or more, more preferably 5 N / 25 mm or more, more preferably 10 N / 25 mm or more, particularly preferably 20 N / 25 mm or more, and even more preferably 27 N / 25 mm or more. When the lower limit of the adhesive strength is as described above, the step-following ability under high-temperature and high-humidity conditions is improved. Furthermore, the adhesive strength of the adhesive sheet 1 according to this embodiment to soda-lime glass preferably has an upper limit of 100 N / 25 mm or less, more preferably 80 N / 25 mm or less, and particularly preferably 50 N / 25 mm or less. When the upper limit of the adhesive strength is as described above, good reworkability is obtained, and in the event of a lamination error, display component parts, particularly expensive display component parts, can be reused.

[0102] Here, the adhesive strength in this specification basically refers to the adhesive strength measured by the 180-degree peel method in accordance with JIS Z0237:2009, and the measurement sample is 25 mm wide and 100 mm long, and the measurement sample is attached to the adherend and pressurized at 0.5 MPa and 50°C for 20 minutes, and then left to stand for 24 hours under conditions of normal pressure, 23°C, and 50% RH, and then measured at a peel speed of 300 mm / min.

[0103] 3. Manufacturing of adhesive sheets In one example of manufacturing the adhesive sheet 1, a coating solution of the adhesive composition P is applied to the release surface of one release sheet 12a (or 12b), and a heat treatment is performed to thermally crosslink the adhesive composition P to form a coating layer, after which the release surface of the other release sheet 12b (or 12a) is superimposed on the coating layer. If a curing period is required, a curing period is allowed, or if no curing period is required, the coating layer becomes the adhesive layer 11 as is. In this way, the adhesive sheet 1 is obtained. The conditions for the heat treatment and curing are as described above.

[0104] In another manufacturing example of the pressure-sensitive adhesive sheet 1, a coating solution of the pressure-sensitive adhesive composition P is applied to the release surface of one release sheet 12a, followed by heat treatment to thermally crosslink the pressure-sensitive adhesive composition P and form a coating layer, thereby obtaining a release sheet 12a with a coating layer. Furthermore, a coating solution of the pressure-sensitive adhesive composition P is applied to the release surface of the other release sheet 12b, followed by heat treatment to thermally crosslink the pressure-sensitive adhesive composition P and form a coating layer, thereby obtaining a release sheet 12b with a coating layer. The release sheet 12a with a coating layer and the release sheet 12b with a coating layer are then bonded together so that the two coating layers are in contact with each other. Multiple release sheets with coating layers may be prepared, and the desired number of coating layers may be bonded together. If a curing period is required, a curing period is allowed. If no curing period is required, the laminated coating layers are left as is, forming the pressure-sensitive adhesive layer 11. This manufacturing example allows stable production even when the pressure-sensitive adhesive layer 11 is thick.

[0105] The coating solution of the pressure-sensitive adhesive composition P can be applied by, for example, bar coating, knife coating, roll coating, blade coating, die coating, gravure coating, or the like.

[0106] [Display body] Examples of the types of display bodies (displays) according to the present embodiment include in-vehicle displays such as automobile instrument panels, car navigation systems, and various meters provided on consoles, displays such as tablet terminals for general users, displays such as commercial tablet terminals and digital signage, and displays such as outdoor digital signage. These displays may be required to have a harmonious appearance with surrounding components and a luxurious feel. However, the display body according to the present invention is not limited to these.

[0107] As shown in Figure 2, the display body 2 of this embodiment is composed of a first display body component 21 (one display body component), a second display body component 22 (another display body component), and an adhesive layer 11 located between them and bonding the first display body component 21 and the second display body component 22 to each other.

[0108] At least one of the first display member component 21 and the second display member component 22 may have a step on at least the surface that is bonded by the adhesive layer 11. In the present embodiment shown in Fig. 2, the first display member component 21 has a step such as a printed layer 3 on the surface on the adhesive layer 11 side.

[0109] The adhesive layer 11 in the display 2 is the adhesive layer 11 of the adhesive sheet 1 described above.

[0110] Examples of the display 2 include a liquid crystal (LCD) display, a light emitting diode (LED) display, an organic electroluminescence (organic EL) display, and electronic paper, and may also be a touch panel.

[0111] The first display member constituting member 21 is preferably a protective panel made of a glass plate, a plastic plate, or a laminate containing these. In this case, the printing layer 3 is generally formed in a frame shape on the pressure-sensitive adhesive layer 11 side of the first display member constituting member 21.

[0112] The glass plate is not particularly limited, and examples thereof include chemically strengthened glass, alkali-free glass, quartz glass, soda-lime glass, barium-strontium-containing glass, aluminosilicate glass, lead glass, borosilicate glass, barium borosilicate glass, etc. The thickness of the glass plate is not particularly limited, but is usually 0.1 to 5 mm, and preferably 0.2 to 2 mm.

[0113] The plastic plate is not particularly limited, and examples thereof include an acrylic plate, a polycarbonate plate, etc. The thickness of the plastic plate is not particularly limited, but is usually 0.2 to 5 mm, and preferably 0.4 to 3 mm.

[0114] On one or both sides of the glass plate or plastic plate, various functional layers (transparent conductive film, metal layer, silica layer, hard coat layer, anti-glare layer, etc.) may be provided, or optical members may be laminated. Furthermore, the transparent conductive film and metal layer may be patterned.

[0115] The second display component 22 is preferably an optical element to be attached to the first display component 21, a display module (e.g., a liquid crystal (LCD) module, a light emitting diode (LED) module, an organic electroluminescence (OLED) module, etc.), an optical element as part of a display module, or a laminate including a display module.

[0116] Examples of the optical member include a shatterproof film, a polarizing plate (polarizing film), a polarizer, a retardation plate (retardation film), a viewing angle compensation film, a brightness improvement film, a contrast improvement film, a liquid crystal polymer film, a diffusion film, a semi-transmitting reflective film, a transparent conductive film, etc. An example of the shatterproof film is a hard coat film obtained by forming a hard coat layer on one side of a base film.

[0117] The material constituting the printing layer 3 is not particularly limited, and known printing materials can be used. The lower limit of the thickness of the printing layer 3, i.e., the height of the step, is preferably 3 μm or more, more preferably 5 μm or more, particularly preferably 7 μm or more, and most preferably 10 μm or more. By setting the lower limit above, sufficient concealment properties can be ensured, such as making the electrical wiring invisible to the viewer. The upper limit is preferably 50 μm or less, more preferably 35 μm or less, particularly preferably 25 μm or less, and even more preferably 20 μm or less. By setting the upper limit above, deterioration of the step-following ability of the pressure-sensitive adhesive layer 11 relative to the printing layer 3 can be prevented.

[0118] To manufacture the display body 2, as an example, one of the release sheets 12a of the adhesive sheet 1 is peeled off, and the exposed adhesive layer 11 of the adhesive sheet 1 is attached to the surface of the first display body component 21 on which the printing layer 3 is present.

[0119] Thereafter, the other release sheet 12b is peeled off from the adhesive layer 11 of the adhesive sheet 1, and the exposed adhesive layer 11 of the adhesive sheet 1 is bonded to the second display body component 22. As another example, the bonding order of the first display body component 21 and the second display body component 22 may be reversed.

[0120] As shown in FIG. 3, the display 2 according to this embodiment preferably has a frame material 4 at the periphery of the display 2. This frame material 4 is preferably black. The preferred ranges for the lightness L*, chromaticity a*, and chromaticity b* of the frame material 4, as defined by the CIE 1976 L*a*b* color system, are the same as those described above for the colors of the surrounding components. By having such a color, the frame material 4 is easily recognized by the human eye as a frame material with a luxurious feel. Furthermore, by having the frame material 4 have the above-described color, the pressure-sensitive adhesive layer 11 according to this embodiment is more integrated with the frame material 4, resulting in better harmony.

[0121] The display body 2 has a sense of unity with the black frame material 4 due to the physical properties of the adhesive layer 11 described above, and has excellent harmony in appearance. In addition, the display body 2 ensures visibility as a display body.

[0122] Furthermore, in the above display body 2, when the adhesive layer 11 is formed from the adhesive composition P, the adhesive layer 11 has excellent step-following properties under high temperature and high humidity conditions, so that even when the display body 2 is placed under high temperature and high humidity conditions (e.g., 85°C, 85% RH), lifting, peeling, etc. near the step is suppressed.

[0123] The above-described embodiments have been described to facilitate understanding of the present invention, and are not intended to limit the present invention. Therefore, each element disclosed in the above embodiments is intended to include all design modifications and equivalents that fall within the technical scope of the present invention.

[0124] For example, either one or both of the release sheets 12a and 12b in the pressure-sensitive adhesive sheet 1 may be omitted, or a desired optical member may be laminated in place of the release sheets 12a and / or 12b. The first display member 21 may not have a step. Furthermore, not only the first display member 21 but also the second display member 22 may have a step on the pressure-sensitive adhesive layer 11 side. [Example]

[0125] The present invention will be explained in more detail below with reference to examples, but the scope of the present invention is not limited to these examples.

[0126] Example 1 1. Preparation of (meth)acrylic acid ester polymer A (meth)acrylic acid ester polymer (A) was prepared by copolymerizing 65 parts by mass of 2-ethylhexyl acrylate, 10 parts by mass of isobornyl acrylate, 10 parts by mass of N-acryloylmorpholine, and 15 parts by mass of 2-hydroxyethyl acrylate by solution polymerization. The molecular weight of this (meth)acrylic acid ester polymer (A) was measured by the method described below, and the weight average molecular weight (Mw) was 500,000.

[0127] 2. Preparation of adhesive composition 100 parts by mass (solids equivalent; same below) of the (meth)acrylic acid ester polymer (A) obtained in step 1 above, 0.2 parts by mass of trimethylolpropane-modified tolylene diisocyanate (manufactured by Toyochem Co., Ltd., product name "BHS8515") as the crosslinking agent (B), 1.0 part by mass of a carbon black-based black pigment (manufactured by Toyocolor Co., Ltd., "Multilac Black") as the colorant (C), and 0.1 parts by mass of 3-glycidoxypropyltrimethoxysilane as the silane coupling agent were mixed, thoroughly stirred, and diluted with methyl ethyl ketone to obtain a coating solution of the adhesive composition.

[0128] Here, the formulations (solid content equivalent) of the pressure-sensitive adhesive compositions when the (meth)acrylic acid ester polymer (A) is taken as 100 parts by mass (solid content equivalent) are shown in Table 1. Details of the abbreviations and the like shown in Table 1 are as follows. [(Meth)acrylic acid ester polymer (A)] 2EHA: 2-ethylhexyl acrylate IBXA: Isobornyl acrylate ACMO: N-acryloylmorpholine HEA: 2-hydroxyethyl acrylate MMA: methyl methacrylate BA: n-butyl acrylate AA: acrylic acid [Crosslinking agent (B)] TDI: Trimethylolpropane-modified tolylene diisocyanate (manufactured by Toyochem Co., Ltd., product name "BHS8515") XDI: Trimethylolpropane-modified xylylene diisocyanate (manufactured by Soken Chemical & Engineering Co., Ltd., product name "TD-75") Epoxy: 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane (manufactured by Mitsubishi Gas Chemical Company, Inc., product name "TETRAD-C") Colorant (C) Pigment: Carbon black pigment (Toyo Color Co., Ltd., "Multilac Black") Dye: Nigrosine black dye (manufactured by Orient Chemical Industry Co., Ltd., product name "NUBIAN BLACK PA-2802")

[0129] 3. Manufacturing of adhesive sheets The adhesive composition coating solution obtained in step 2 above was applied using a knife coater to the release-treated surface of a heavy-release release sheet (manufactured by Lintec Corporation, product name "SP-PET752150"), one side of which had been release-treated with a silicone-based release agent, and then heated at 90°C for 1 minute to form a coating layer (thickness: 50µm). The coating layer side of the obtained heavy-release release sheet with coating layer was laminated to the release-treated surface of a light-release release sheet (manufactured by Lintec Corporation, product name "SP-PET381130"), one side of which had been release-treated with a silicone-based release agent, and the mixture was aged for 7 days under conditions of 23°C and 50% RH to produce an adhesive sheet consisting of heavy-release release sheet / adhesive layer (thickness: 50µm) / light-release release sheet.

[0130] The thickness of the pressure-sensitive adhesive layer is a value measured in accordance with JIS K7130 using a constant pressure thickness measuring instrument (manufactured by Teclock Corporation, product name "PG-02").

[0131] [Examples 2 to 14, Comparative Examples 1 to 4] An adhesive sheet was produced in the same manner as in Example 1, except that the types and proportions of the monomers constituting the (meth)acrylic acid ester polymer (A), the weight average molecular weight (Mw) of the (meth)acrylic acid ester polymer (A), the type and amount of the crosslinking agent (B), the type and amount of the colorant (C), the amount of the silane coupling agent, the amount of the rust inhibitor (N,N-bis(2-ethylhexyl)-4-methyl-1H-benzotriazole-1-methylamine) as an additive, and the thickness of the adhesive layer were changed as shown in Table 1.

[0132] The pressure-sensitive adhesive sheet of Example 8 was produced as follows. A coating solution of the pressure-sensitive adhesive composition prepared in the same manner as in Example 1 was applied by a knife coater to the release-treated surface of a heavy-release release sheet (manufactured by Lintec Corporation, product name "SP-PET752150"), one side of which had been release-treated with a silicone-based release agent, and then heated at 90°C for 1 minute to form a coating layer (thickness: 50µm). Also, a coating solution of the pressure-sensitive adhesive composition prepared in the same manner as in Example 1 was applied by a knife coater to the release-treated surface of a light-release release sheet (manufactured by Lintec Corporation, product name "SP-PET382120"), one side of which had been release-treated with a silicone-based release agent, and then heated at 90°C for 1 minute to form a coating layer (thickness: 50µm).

[0133] Next, the heavy release type release sheet with the coating layer obtained above and the light release type release sheet with the coating layer obtained above were bonded together so that the two coating layers were in contact with each other, and the resulting mixture was aged for 7 days at 23°C and 50% RH to produce an adhesive sheet consisting of a heavy release type release sheet / adhesive layer (thickness: 100 μm) / light release type release sheet.

[0134] Here, X×Z was calculated when the content of the colorant in the pressure-sensitive adhesive layer (pressure-sensitive adhesive composition) formed in the Examples and Comparative Examples was X mass % and the thickness of the pressure-sensitive adhesive layer was Z μm. The results are shown in Table 1.

[0135] The weight average molecular weight (Mw) mentioned above is a weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC) under the following conditions (GPC measurement). <Measurement conditions> GPC measuring device: Tosoh HLC-8020 GPC columns (passed in the following order): Tosoh Corporation TSK guard column HXL-H TSK gel GMHXL (×2) TSK gel G2000HXL Measurement solvent: tetrahydrofuran ·Measurement temperature: 40℃

[0136] [Test Example 1] (Measurement of gel fraction) The pressure-sensitive adhesive sheets obtained in the examples and comparative examples were cut to a size of 80 mm x 80 mm, the pressure-sensitive adhesive layer was wrapped in a polyester mesh (mesh size 200), and the mass was weighed on a precision balance. The mass of the mesh alone was subtracted to calculate the mass of the pressure-sensitive adhesive alone. This mass was designated M1.

[0137] Next, the adhesive wrapped in the polyester mesh was immersed in ethyl acetate at room temperature (23°C) for 24 hours. The adhesive was then removed and air-dried for 24 hours at 23°C and 50% relative humidity, and then dried in an oven at 80°C for 12 hours. After drying, the mass was measured using a precision balance, and the mass of the mesh alone was subtracted to calculate the mass of the adhesive alone. This mass was designated M2. The gel fraction (%) was expressed as (M2 / M1) x 100. The results are shown in Table 2.

[0138] [Test Example 2] (Measurement of total light transmittance) The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet obtained in the Examples and Comparative Examples was attached to glass to prepare a measurement sample. After background measurement was performed on the glass, the total light transmittance (%) of the measurement sample was measured using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "NDH-5000") in accordance with JIS K7361-1:1997. The results are shown in Table 2.

[0139] [Test Example 3] (Measurement of L*a*b*) The lightness L*, chromaticity a*, and chromaticity b* defined by the CIE 1976 L*a*b* color system were measured for the adhesive layers of the adhesive sheets obtained in the Examples and Comparative Examples using a simultaneous spectrophotometric colorimeter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "SQ2000"). The results are shown in Table 2.

[0140] [Test Example 4] (Haze Value Measurement) The haze values ​​(%) of the pressure-sensitive adhesive layers of the pressure-sensitive adhesive sheets obtained in the Examples and Comparative Examples were measured using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "NDH-5000") in accordance with JIS K7136: 2000. The results are shown in Table 2.

[0141] Test Example 5 (Measurement of storage modulus) The release sheets were peeled off from the pressure-sensitive adhesive sheets obtained in the Examples and Comparative Examples, and multiple pressure-sensitive adhesive layers were laminated to a thickness of 3 mm. A cylindrical object with a diameter of 8 mm (height of 3 mm) was punched out from the resulting pressure-sensitive adhesive layer laminate, and this was used as a sample.

[0142] The storage modulus (MPa) of the above samples was measured under the following conditions by a torsional shear method using a viscoelasticity measuring device (manufactured by Physica, product name "MCR300") in accordance with JIS K7244-6. The results are shown in Table 2. Measurement frequency: 1Hz Measurement temperature: 23℃

[0143] [Test Example 6] (Measurement of adhesive strength) The light-release release sheet was peeled off from the pressure-sensitive adhesive sheets obtained in the Examples and Comparative Examples, and the exposed pressure-sensitive adhesive layer was attached to an easy-adhesion layer of a polyethylene terephthalate (PET) film (manufactured by Toyobo Co., Ltd., product name "PET A4300", thickness: 100 μm) having an easy-adhesion layer, to obtain a release sheet / pressure-sensitive adhesive layer / PET film laminate. The obtained laminate was cut into a 25 mm wide, 100 mm long sample.

[0144] The heavy-release release sheet was peeled from the sample at 23°C and 50% RH, and the exposed adhesive layer was attached to soda-lime glass (manufactured by Nippon Sheet Glass Co., Ltd.). The sample was then pressurized at 0.5 MPa and 50°C for 20 minutes in a Kurihara Manufacturing autoclave. After leaving the sample at 23°C and 50% RH for 24 hours, the adhesive strength (N / 25 mm) was measured using a tensile tester (manufactured by Orientec Co., Ltd., product name "Tensilon") at a peel rate of 300 mm / min and a peel angle of 180°. Measurements were conducted under conditions other than those described here in accordance with JIS Z0237:2009. The results are shown in Table 2.

[0145] [Test Example 7] (Evaluation of Appearance Harmony) The adhesive sheets obtained in the examples and comparative examples were cut to a size of 70 mm length x 70 mm width, and the adhesive layer of the adhesive sheet was sandwiched between two pieces of soda lime glass (manufactured by Nippon Sheet Glass Co., Ltd., 70 mm length x 70 mm width x 1.1 mm thickness), and this was used as a sample.

[0146] The resulting sample was placed on a black background paper (L*: 29.8, a*: -0.7, b*: 0.6). The sample was then visually inspected under a three-band fluorescent lamp (distance from the lamp: 200 cm) to determine whether it blended in with the background (i.e., whether it was integrated with the background). The appearance harmony was evaluated according to the following criteria. The results are shown in Table 2. ◎: The sample blended very well with the background. ○: The sample blended in with the background to some extent. ×: The sample clearly did not blend in with the background.

[0147] The color of the black-printed paper (L*a*b* defined by the CIE 1976 L*a*b* color system) was measured using a spectrophotometer (manufactured by BYK, product name "Spectro-Guide").

[0148] [Test Example 8] (Evaluation of character visibility) On a 15.6-inch display with a resolution of 1366 x 768 (manufactured by Fujitsu, product name "LITEBOOK A574 / H"), black text (font: MS P Gothic) was displayed at 100% resolution on a white background, with sizes ranging from 5 to 20 points (in 1-point increments).

[0149] A sample prepared in the same manner as in Test Example 7 was placed on the display. The size of the characters that could be seen with the naked eye was checked at a position 50 cm from the display, and character visibility was evaluated according to the following criteria. The results are shown in Table 2. ◎: 8-point characters were visible. ○: 8-point characters were not completely visible, but 15-point characters were visible. ×: 15-point characters were not visible.

[0150] [Test Example 9] (Evaluation of step-following ability) (a) Preparation of evaluation samples On the surface of a glass plate (NSG Precision, product name "Corning Glass Eagle XG", 90 mm length x 50 mm width x 0.5 mm thickness), ultraviolet-curable ink (Teikoku Ink Co., Ltd., product name "POS-911 Sumi") was screen-printed in the shape of a picture frame (outer dimensions: 90 mm length x 50 mm width, 5 mm width). Then, ultraviolet light (80 W / cm 2 The printed ultraviolet-curable ink was cured using a printing method (two metal halide lamps, lamp height 15 cm, belt speed 10-15 m / min) to produce a stepped glass plate with printed steps (step height: 5 μm, 10 μm).

[0151] The light-release release sheet was peeled off from the pressure-sensitive adhesive sheets obtained in the Examples and Comparative Examples, and the exposed pressure-sensitive adhesive layer was attached to an easy-adhesion layer of a polyethylene terephthalate film (manufactured by Toyobo Co., Ltd., product name "PET A4300", thickness: 100 μm) having an easy-adhesion layer. Next, the heavy-release release sheet was peeled off to expose the pressure-sensitive adhesive layer. Then, using a laminator (manufactured by Fujipla Co., Ltd., product name "LPD3214"), the above laminate was laminated onto each stepped glass plate so that the pressure-sensitive adhesive layer covered the entire frame-shaped print, and this was used as an evaluation sample.

[0152] (b) Evaluation of initial step-following ability The resulting evaluation samples were autoclaved for 30 minutes at 50°C and 0.5 MPa, and the initial step-conforming ability was evaluated based on the following criteria. Step-conforming ability was judged to be good if the printed step was completely filled by the adhesive layer, and was judged to be unable to conform to the printed step if lifting or peeling was observed at the interface between the printed step and the adhesive layer. The results are shown in Table 2. ◎: Good with a printing step of 10 μm ○: Good with a printing step of 5 μm ×: Peeling and lifting occurred at a printing step of 5 μm

[0153] (c) Evaluation of bump-following ability after durability test For samples with good initial conformability, after the autoclave treatment, they were left at normal pressure, 23°C, and 50% RH for 24 hours. They were then stored under humid heat conditions of 85°C and 85% RH for 72 hours (durability test), and the conformability after durability was evaluated based on the same criteria as above. The results are shown in Table 2.

[0154] [Table 1]

[0155] [Table 2]

[0156] As can be seen from Table 2, the adhesive sheets obtained in the examples were excellent in appearance harmony and character visibility. Furthermore, the adhesive sheets obtained in Examples 1 to 10 and 12 to 14 were also excellent in step-conforming ability. [Industrial Applicability]

[0157] The pressure-sensitive adhesive sheet of the present invention can be suitably used, for example, for bonding display component parts together in a display having a black frame material, particularly for bonding a protective panel having a step to a desired display component part. [Explanation of symbols]

[0158] 1...Adhesive sheet 11...Adhesive layer 12a, 12b...Release sheet 2...Display body 21...First display component 22... Second display component 3...Printing layer 4…Frame material

Claims

1. A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer for bonding one display component and another display component together over the entire surface of the display, The display body has a black frame material, the pressure-sensitive adhesive layer is made of a pressure-sensitive adhesive containing a colorant, the colorant is black, The pressure-sensitive adhesive layer has a total light transmittance of 3% or more, The lightness L* of the pressure-sensitive adhesive layer as defined by the CIE 1976 L*a*b* color system is 94.1 or less. A pressure-sensitive adhesive sheet characterized by:

2. A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer for bonding one display component and another display component together over the entire surface of the display, The display body has a black frame material, the pressure-sensitive adhesive layer is made of a pressure-sensitive adhesive containing a colorant, the colorant is black, the haze value of the pressure-sensitive adhesive layer is 80% or less, The lightness L* of the pressure-sensitive adhesive layer as defined by the CIE 1976 L*a*b* color system is 94.1 or less. A pressure-sensitive adhesive sheet characterized by:

3. 3. The adhesive sheet according to claim 1, wherein the one display component is a protection panel, and the other display component is a display module.

4. 4. The pressure-sensitive adhesive sheet according to claim 1, wherein the pressure-sensitive adhesive layer has a haze value of 80% or less.

5. 5. The pressure-sensitive adhesive sheet according to claim 1, wherein the colorant is a pigment or a dye.

6. 6. The pressure-sensitive adhesive sheet according to claim 1, wherein the pressure-sensitive adhesive is an acrylic pressure-sensitive adhesive.

7. Two release sheets, the pressure-sensitive adhesive layer sandwiched between the two release sheets so as to be in contact with the release surfaces of the two release sheets; The pressure-sensitive adhesive sheet according to any one of claims 1 to 6, comprising:

8. One display component; Other display component parts, an adhesive layer that bonds the first display component and the second display component together over the entire surface; A display comprising: The display body has a black frame material, The pressure-sensitive adhesive layer is the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to any one of claims 1 to 7. A display characterized by:

9. 9. The display according to claim 8, wherein at least one of the first display member and the second display member has a step on at least the surface to be bonded by the adhesive layer.

Images