Adhesive sheet, display body, and method for manufacturing display body

Abstract

The present invention provides an adhesive sheet that improves the design of a display body, and a display body that improves the design. The adhesive sheet (1) includes an adhesive layer (11) for bonding one display body component (21) to another display body component (22). The adhesive layer (11) is composed of an active energy radiation curable adhesive containing a colorant. The total light transmittance of the adhesive layer (11) is 3% or more, and the lightness L* of the adhesive layer (11) as specified by the CIE1976 L*a*b* color system is 95 or less.

Description

[0001] This invention is a divisional application of Chinese Patent Application No. 201911270223.9, filed on December 11, 2019, entitled "Adhesive Sheet, Display Body and Method for Manufacturing Display Body". This application claims priority to Japanese Patent Application No. 2018-236770, filed on December 18, 2018. Technical Field

[0002] The present invention relates to an adhesive sheet for bonding components of a display body, a display body using the adhesive sheet, and a method for manufacturing the display body. Background Technology

[0003] In recent years, liquid crystal display devices have been increasingly used in various display devices, such as in-vehicle displays installed in car dashboards, car navigation systems, and various gauges on the console; displays for general users such as tablet terminals; displays for commercial tablet terminals or digital signage; and displays for outdoor digital signage.

[0004] As mentioned above, in displays, particularly those used in vehicles, it is sometimes required that the display maintain a sense of unity with its surrounding components, such as the frame, when the lights are off, thereby enhancing the design. To address this, coloring the display can be considered; for example, patent documents 1-4 disclose an invention related to coloring a display.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2000-313871

[0008] Patent Document 2: Japanese Patent Application Publication No. 2009-188298

[0009] Patent Document 3: Japanese Patent Application Publication No. 2012-234028

[0010] Patent Document 4: Japanese Patent Application Publication No. 2017-57375 Summary of the Invention

[0011] The technical problem to be solved by the present invention

[0012] However, since the purposes of coloring the techniques disclosed in the aforementioned patent documents 1 to 4 are all different, they fail to give the display a sense of unity with the surrounding components and improve the design.

[0013] The present invention was made in view of the above-mentioned actual situation, and its object is to provide an adhesive sheet that can improve the design of a display body, and a display body that improves the design.

[0014] Technical means to solve technical problems

[0015] To achieve the above objectives, firstly, 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 formed of an active energy radiation curable adhesive containing a colorant, the total light transmittance of the adhesive layer is 3% or more, and the lightness L* of the adhesive layer as specified by the CIE1976 L*a*b* color system is 95 or less (Invention 1).

[0016] According to the invention described above (Invention 1), when the adhesive sheet is applied to a display body, the design of the display body can be improved (for example, aesthetic harmony). For instance, when the display body is turned off, it can be given a sense of unity with surrounding components, such as a black frame, thereby improving aesthetic harmony and conveying a sense of sophistication. Furthermore, by having the aforementioned total light transmittance, the visibility of the display body can be ensured.

[0017] In the above invention (Invention 1), it is preferred that the haze value of the adhesive layer is 0.01% or more and 80% or less (Invention 2).

[0018] In the above inventions (Inventions 1 and 2), the colorant is preferably a black pigment or dye (Invention 3).

[0019] In the above inventions (Inventions 1 to 3), it is preferable that when the content of the colorant in the adhesive is set to X mass% and the thickness of the adhesive layer is set to Z μm, the following formula (I) (Invention 4) is satisfied.

[0020] 5 ≤ X × Z < 300 ···(I)

[0021] In the above inventions (Inventions 1 to 4), it is preferred that the content of the colorant in the active energy ray curable adhesive is 0.01% by mass or more and 2.0% by mass or less (Invention 5).

[0022] In the above inventions (Inventions 1 to 5), the adhesive is preferably an acrylic adhesive (Invention 6).

[0023] In the above inventions (Inventions 1-6), the adhesive is preferably formed by crosslinking an adhesive composition containing (meth)acrylate polymer (A), crosslinking agent (B), active energy ray curable component (C) and colorant (D) (Invention 7).

[0024] In the above inventions (Inventions 1 to 7), it is preferable that the adhesive sheet has two release sheets and the adhesive layer, and the adhesive layer is held by the release sheets in such a way that it contacts the release surfaces of the two release sheets (Invention 8).

[0025] Second, the present invention provides a display body comprising a display body component, another display body component, and a cured adhesive layer for bonding the one display body component and the other display body component together. The display body is characterized in that the cured adhesive layer is a cured adhesive layer (Invention 9) formed by curing the adhesive layer of the adhesive sheet (Invention 1-8) with active energy rays.

[0026] In the above invention (Invention 9), preferably at least one of the one display body component and the other display body component has a step at least on the side of the surface that is adhered to by the cured adhesive layer (Invention 10).

[0027] In the above inventions (Inventions 9 and 10), it is preferable that the display body has a black frame (Invention 11).

[0028] Third, the present invention provides a method for manufacturing a display body, characterized in that a laminate is formed by bonding one display body component to another display body component via an adhesive layer of the adhesive sheet (Invention 1-8), and the adhesive layer of the laminate is irradiated with active energy rays to cure the adhesive layer, thereby forming a cured adhesive layer (Invention 12).

[0029] Invention Effects

[0030] The adhesive sheet according to the present invention can improve the design flexibility of the display body. Furthermore, the design flexibility of the display body according to the present invention is improved. Attached Figure Description

[0031] Figure 1 This is a cross-sectional view of an adhesive sheet according to one embodiment of the present invention.

[0032] Figure 2 This is a cross-sectional view of a display body according to one embodiment of the present invention.

[0033] Figure 3 This is a top view of a display body with a frame, according to one embodiment of the present invention.

[0034] Explanation of reference numerals in the attached figures

[0035] 1: Adhesive sheet; 11: Adhesive layer; 12a, 12b: Release sheet; 2: Display body; 11': Cured adhesive layer; 21: First display body component; 22: Second display body component; 3: Printed layer; 4: Frame material. Detailed Implementation

[0036] The embodiments of the present invention will be described below.

[0037] [Adhesive sheet]

[0038] An adhesive sheet according to one embodiment of the present invention includes an adhesive layer for bonding one display body component to another display body component. The adhesive sheet is preferably formed by laminating a release liner on one or both sides of the adhesive layer. The display body and display body component will be described below.

[0039] Figure 1 The diagram shows a specific structure of the adhesive sheet as an example of this embodiment.

[0040] like Figure 1 As shown, the adhesive sheet 1 consists of two release sheets 12a and 12b and an adhesive layer 11. The adhesive layer 11 is held by the two release sheets 12a and 12b in contact with their release surfaces. Furthermore, in this specification, the release surface of a release sheet refers to the surface of the release sheet that has release properties, including either the surface that has undergone release treatment or the surface that exhibits release properties even without release treatment.

[0041] 1. Each component

[0042] 1-1. Adhesive layer

[0043] The adhesive layer 11 of the adhesive sheet 1 in this embodiment is composed of an active energy radiation-curable adhesive containing a colorant. Furthermore, the total light transmittance of the adhesive layer 11 (the value measured according to JIS K7361-1:1997) is 3% or more, and the lightness L* of the adhesive layer 11, as specified by the CIE 1976 L*a*b* color system, is 95 or less. The method for measuring the lightness L* in this specification is as described in the test examples below.

[0044] When the adhesive layer 11, which satisfies the aforementioned physical properties, is applied to the display body, the design of the display body when the lights are off can be improved (for example, aesthetic harmony). Specifically, it can give the display body a sense of unity with surrounding components, such as with the black frame material, thereby improving aesthetic harmony and conveying a sense of sophistication. Furthermore, by ensuring that the total light transmittance is 3% or more, the visibility of the display body can be guaranteed.

[0045] Specifically, examples of the aforementioned surrounding components include automotive dashboards, which have a lightness L* of 23.2, chromaticity a* of -0.5, and chromaticity b* of -1.5 as specified in the CIE 1976 L*a*b* color system. For the colors of these surrounding components, lightness L* of 5 to 95, chromaticity a* of -40 to 40, and chromaticity b* of -40 to 40 are preferred; lightness L* of 10 to 80, chromaticity a* of -30 to 30, and chromaticity b* of -30 to 30 are particularly preferred; and lightness L* of 15 to 70, chromaticity a* of -20 to 20, and chromaticity b* of -20 to 20 are even more preferred. The adhesive sheet 1 of this embodiment can be applied to a display body with surrounding components having the aforementioned colors.

[0046] From the perspective of visibility of the display body, the total light transmittance of the adhesive layer 11 is 3% or more, preferably 10% or more, particularly preferably 25% or more, and even more preferably 50% or more. There is no particular upper limit to the total light transmittance, which is generally 100% or less. However, considering its relationship with the aforementioned brightness L*, it is preferably 98% or less, particularly preferably 95% or less, and even more preferably 90% or less.

[0047] Furthermore, from the perspective of improving design based on aesthetic harmony, the lightness L* of the adhesive layer 11 is 95 or less, preferably 92 or less, particularly preferably 89 or less, and even more preferably 86 or less. On the other hand, from the perspective of improving design based on aesthetic harmony and the visibility of the display, the lower limit of this lightness L* is preferably 10 or more, more preferably 20 or more, particularly preferably 30 or more, even more preferably 40 or more, and most preferably 55 or more.

[0048] Furthermore, the chromaticity a* of the adhesive layer 11, as specified by the CIE 1976 L*a*b* color system, is preferably -40 or higher, more preferably -30 or higher, particularly preferably -20 or higher, further preferably -15 or higher, and most preferably -10 or higher. In addition, this chromaticity a* is preferably 40 or lower, more preferably 30 or lower, particularly preferably 20 or lower, further preferably 15 or lower, and most preferably 10 or lower. By ensuring that the chromaticity a* is within the above-mentioned range, the design, especially the design (particularly the appearance harmony) of the display for automotive applications, is further improved.

[0049] Furthermore, the chromaticity b* of the adhesive layer 11, as specified by the CIE 1976 L*a*b* color system, is preferably -40 or higher, more preferably -30 or higher, particularly preferably -20 or higher, further preferably -15 or higher, and most preferably -10 or higher. Additionally, this chromaticity b* is preferably 40 or lower, more preferably 30 or lower, particularly preferably 20 or lower, further preferably 15 or lower, and most preferably 10 or lower. By ensuring the chromaticity b* is within the above-mentioned range, the design, especially the design (particularly aesthetic harmony) of automotive displays, is further improved.

[0050] The haze value of the adhesive layer 11 is typically 0% or more. When the colorant in the adhesive layer 11 is a dye, it is preferably 0.01% or more, more preferably 0.05% or more, and particularly preferably 0.1% or more. Furthermore, when the colorant in the adhesive layer 11 is a pigment, the haze value of the adhesive layer 11 is preferably 0.1% or more, more preferably 1% or more, particularly preferably 6% or more, and most preferably 12% or more. By setting the lower limit of the haze value of the adhesive layer 11 to the above-mentioned values, it is easier to give the resulting display a sense of unity with surrounding components (e.g., frame material). On the other hand, the haze value of the adhesive layer 11 is preferably 80% or less, more preferably 70% or less, particularly preferably 60% or less, further preferably 50% or less, and most preferably 40% or less. By setting the upper limit of the haze value of the adhesive layer 11 to the above-mentioned values, the total light transmittance easily falls within the above-mentioned range, and furthermore, it is easier to give the resulting display a sense of unity with surrounding components (e.g., frame material). In addition, the haze values ​​in this manual are measured according to JISK7136:2000.

[0051] Furthermore, the total light transmittance, haze value, lightness L*, chromaticity a*, and chromaticity b* of the adhesive layer 11 remain almost unchanged after the adhesive layer 11 is cured by irradiation with active energy rays to form a cured adhesive layer.

[0052] By appropriately selecting the type and content of colorants contained in the adhesive constituting the adhesive layer 11, the above-mentioned total light transmittance and brightness L* (as well as chromaticity a* and b* and haze value) can be achieved.

[0053] The aforementioned colorant can be a pigment or a dye. The pigment can be inorganic or organic. From the perspective of the durability (especially anti-foaming properties) 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 be represented, generally preferably dark or deep colors such as black, brown, navy blue, purple, or blue, with black being particularly preferred.

[0054] Inorganic pigments include, for example, carbon black, cobalt pigments, iron pigments, chromium pigments, titanium pigments, vanadium pigments, zirconium pigments, molybdenum pigments, ruthenium pigments, platinum pigments, ITO (indium tin oxide) pigments, and ATO (antimony tin oxide) pigments.

[0055] In addition, amines can be listed as examples of organic pigments and organic dyes. (aminium) pigments, anthocyanin pigments, croconium pigments, squarylium pigments, chamomile blue Azulenium pigments, polymethystyl pigments, naphthoquinone pigments, pyranonium pigments, phthalocyanine pigments, naphtholactam pigments, azo pigments, condensed azo pigments, indigo pigments, perinone pigments, perylene pigments, dioxazine pigments, quinacridone pigments, isoindolineone pigments, quinophthalone pigments, pyrrole pigments, thioindigo pigments, metal complex pigments (metal complex salt dyes), dithiol metal complex pigments, indolephenol pigments, triarylmethane pigments, anthraquinone pigments, dioxazine pigments, naphthophenol pigments, azomethyl alkaloid pigments, benzimidazole ketone pigments, pinantrone pigments, and threne pigments, etc.

[0056] Examples of black pigments include carbon black, copper oxide, iron oxide, manganese dioxide, aniline black, and activated carbon. Additionally, examples of black dyes include high-concentration plant-based dyes and azo dyes.

[0057] In order to obtain the desired physical properties, the aforementioned pigments or dyes can be appropriately mixed and used in the adhesive layer 11.

[0058] Among the aforementioned colorants, carbon black, aniline black dyes, and chromate black dyes are preferred from the perspective of easily achieving the aforementioned total light transmittance and lightness L* (and haze value) and easily reflecting the overall sense of unity with surrounding components. Furthermore, the surface of the carbon black may be subjected to a prescribed treatment (e.g., solvent treatment), or it may not require surface treatment.

[0059] When the thickness of the adhesive layer 11 is set to Z μm, it is preferable that the content of the colorant in the adhesive, X by mass%, is a value that satisfies the following formula (I).

[0060] 5 ≤ X × Z < 300 ···(I)

[0061] By keeping the values ​​of X×Z within the above range, the above total light transmittance and brightness L* (and haze value) can be easily achieved. Furthermore, the thickness of the adhesive layer 11 in this specification is a value measured according to JIS K7130.

[0062] From the above perspective, the lower limit of X×Z is preferably 8 or more, particularly preferably 10 or more, and even more preferably 15 or more. Furthermore, the upper limit of X×Z is preferably 250 or less, more preferably 150 or less, particularly preferably 100 or less, and from the perspective of anti-foaming properties, even more preferably 60 or less, and most preferably 30 or less.

[0063] To ensure that the value of X×Z easily falls within the aforementioned range, the lower limit of the colorant content (X by mass%) in the adhesive is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, particularly preferably 0.1% by mass or more, and even more preferably 0.12% by mass or more. Furthermore, the upper limit of the colorant content (X by mass%) is preferably 2.0% by mass or less, more preferably 1.0% by mass or less, particularly preferably 0.5% by mass or less, and even more preferably 0.2% by mass or less.

[0064] The type of adhesive used in the adhesive layer 11 constituting the adhesive sheet 1 of this embodiment is not particularly limited as long as it is radioactively cured by active energy radiation. From the perspectives of adhesive properties, optical properties, and durability (especially anti-foaming properties), radioactively cured acrylic adhesives are preferred. This acrylic adhesive can be any of the following: emulsion type, solvent type, or solvent-free type; and it can be any of the following: cross-linked type or non-cross-linked type. Among these, a radioactively cured cross-linked acrylic adhesive is preferred.

[0065] The adhesive described above is particularly preferred as being formed by crosslinking an adhesive composition (hereinafter, sometimes referred to as "adhesive composition P") containing a (meth)acrylate polymer (A), a crosslinking agent (B), an active energy radiation curable component (C), and a colorant (D). The colorant (D) is the aforementioned colorant. The adhesive obtained from this adhesive composition P exhibits excellent optical properties, adhesion, and durability (step-following performance under high temperature and humidity conditions, and anti-foaming properties). Furthermore, in this specification, (meth)acrylate refers to both acrylic acid and methacrylic acid. Other similar terms are also used. Additionally, the term "polymer" also includes the concept of "copolymer."

[0066] (1) Components of the adhesive composition

[0067] (1-1) (Meth)acrylate polymer (A)

[0068] The (meth)acrylate polymer (A) of this embodiment preferably contains a monomer with reactive groups as the monomer unit constituting the polymer, and the monomer with reactive groups has reactive groups within the molecule that react with the crosslinking agent (B). By reacting the reactive groups from the monomer with the crosslinking agent (B), a crosslinked structure (three-dimensional network structure) is formed, thereby obtaining an adhesive with the desired cohesive strength.

[0069] As monomers containing reactive groups, preferred examples include monomers having a hydroxyl group in the molecule (hydroxyl-containing monomers), monomers having a carboxyl group in the molecule (carboxyl-containing monomers), and monomers having an amino group in the molecule (amino-containing monomers). Among these, hydroxyl-containing monomers and carboxyl-containing monomers with excellent reactivity with the crosslinking agent (B) are preferred, and hydroxyl-containing monomers with minimal adverse effects on the adhered material are particularly preferred.

[0070] Examples of hydroxyl-containing monomers include 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, 3-hydroxybutyl methacrylate, and 4-hydroxybutyl methacrylate, among other hydroxyalkyl methacrylates. From the perspective of the reactivity of the hydroxyl groups in the obtained methacrylate polymer (A) with the crosslinking agent (B) and the copolymerization properties of the hydroxyl groups with other monomers, hydroxyalkyl methacrylates having 1 to 4 carbon atoms are preferred. Specifically, 2-hydroxyethyl methacrylate and 4-hydroxybutyl methacrylate are preferred examples, and 2-hydroxyethyl acrylate or 4-hydroxybutyl acrylate are particularly preferred. These hydroxyl-containing monomers can be used alone or in combination of two or more.

[0071] Examples of carboxyl-containing monomers include acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, citraconic acid, and other olefinic unsaturated carboxylic acids. Among these, acrylic acid is preferred based on the reactivity of the carboxyl group in the resulting (meth)acrylate polymer (A) with the crosslinking agent (B) and the copolymerization properties of the carboxyl group with other monomers. These carboxyl-containing monomers can be used alone or in combination of two or more.

[0072] Examples of amino-containing monomers include aminoethyl (meth)acrylate and n-butylaminoethyl (meth)acrylate. These amino-containing monomers can be used alone or in combination of two or more.

[0073] For the (meth)acrylate polymer (A), as a monomer unit constituting the polymer, it is preferable to contain 1% or more by mass, particularly preferably 5% or more by mass, and further preferably 8% or more by mass of a monomer containing a reactive group, based on the following limits. When the monomer containing the reactive group is a hydroxyl-containing monomer, it is particularly preferable to contain 15% or more by mass. Furthermore, for the (meth)acrylate polymer (A), as a monomer unit constituting the polymer, it is preferable to contain 35% or less by mass, particularly preferably 30% or less by mass, and further preferably 25% or less by mass, based on the upper limit. When the monomer containing the reactive group is a carboxyl-containing monomer, it is preferable to contain 20% or less by mass, and particularly preferably 12% or less by mass. If the (meth)acrylate polymer (A) contains a monomer containing a reactive group as a monomer unit in the above-mentioned amounts, a good cross-linking structure is formed in the obtained adhesive, and the desired cohesive strength is obtained. Furthermore, the dispersibility of the colorant (D) in the adhesive tends to improve, resulting in good reproducibility and uniformity of the total light transmittance and lightness L* (as well as chromaticity a* and b* and haze value), exhibiting excellent appearance harmony and text visibility. Moreover, when the monomer containing the reactive group is a hydroxyl-containing monomer, if its content is 15% by mass or more, a specified amount of hydroxyl groups will remain in the adhesive. Hydroxyl groups are hydrophilic groups; if such hydrophilic groups are present in the adhesive in a specified amount, even when the adhesive is placed under high temperature and high humidity conditions, the compatibility of the adhesive with water immersed in the adhesive under these conditions is good. As a result, whitening of the adhesive when returned to normal temperature and humidity is suppressed (excellent resistance to damp heat whitening).

[0074] Furthermore, the (meth)acrylate polymer (A) preferably does not contain carboxyl-containing monomers as monomer units constituting the polymer. Since carboxyl groups are acidic components, by not containing carboxyl-containing monomers, even when the adhesive adheres to substances that cause adverse effects due to acid, such as transparent conductive films or metal films like tin-doped indium oxide (ITO), the aforementioned adverse effects (corrosion, changes in resistance, etc.) caused by acid can be suppressed. However, it is also permissible to contain a specified amount of carboxyl-containing monomers to the extent that such adverse effects are not caused. Specifically, in the (meth)acrylate polymer (A), as monomer units, it is permissible to contain carboxyl-containing monomers in an amount of 0.1% by mass or less, preferably 0.01% by mass or less, and even more preferably 0.001% by mass or less.

[0075] The (meth)acrylate polymer (A) preferably contains alkyl (meth)acrylate as a monomer unit constituting the polymer. This results in good adhesion. The alkyl group can be linear or branched.

[0076] From the perspective of adhesion, alkyl methacrylates with 1 to 20 carbon atoms in the alkyl group are preferred. Examples of alkyl methacrylates with 1 to 20 carbon atoms in the alkyl group include methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, n-pentyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, isooctyl methacrylate, n-decyl methacrylate, n-dodecyl methacrylate, tetradecyl methacrylate, hexadecyl methacrylate, and octadecyl methacrylate. From the perspective of further improving adhesion, alkyl methacrylates with 1 to 8 carbon atoms in the alkyl group are preferred, with methyl methacrylate, n-butyl methacrylate, or 2-ethylhexyl methacrylate being particularly preferred, and methyl methacrylate, n-butyl methacrylate, or 2-ethylhexyl methacrylate being even more preferred. In addition, these alkyl (meth)acrylates can be used alone or in combination of two or more.

[0077] The (meth)acrylate polymer (A) preferably contains 40% or more, particularly preferably 50% or more, and even more preferably 60% or more of alkyl (meth)acrylate as a monomer unit constituting the polymer. If the lower limit of the alkyl (meth)acrylate content is as described above, the (meth)acrylate polymer (A) can exhibit suitable adhesive properties. Furthermore, the (meth)acrylate polymer (A) preferably contains 99% or less, particularly preferably 95% or less, and even more preferably 90% or less of alkyl (meth)acrylate as a monomer unit constituting the polymer. If the upper limit of the alkyl (meth)acrylate content is as described above, other monomer components, such as monomers containing reactive functional groups, can be introduced into the (meth)acrylate polymer (A) in suitable amounts.

[0078] The aforementioned (meth)acrylate polymer (A) preferably contains monomers with an intramolecular alicyclic structure (aricyclic monomers) as monomeric units constituting the polymer. Since alicyclic monomers have a large volume, it is presumed that their presence in the polymer increases the spacing between polymers, resulting in adhesives with excellent flexibility. Consequently, the step-following properties of the adhesive become excellent.

[0079] The carbon rings in the alicyclic monomer can be saturated or partially unsaturated. Furthermore, the alicyclic structure can be monocyclic or polycyclic, such as bicyclic or tricyclic. From the perspective of ensuring appropriate spacing between the resulting (meth)acrylate polymers (A) and imparting higher stress relief to the adhesive, the aforementioned alicyclic structure is preferably a polycyclic alicyclic structure (polycyclic structure). Further, considering the compatibility of the (meth)acrylate polymer (A) with other components, the aforementioned polycyclic structure is particularly preferably bicyclic to tetracyclic. Also, similarly, from the perspective of imparting stress relief, the number of carbon atoms in the alicyclic structure (referring to the total number of carbon atoms in the ring-forming portion; when multiple rings exist independently, it refers to the total number of carbon atoms in the multiple rings) is generally preferably 5 or more, and particularly preferably 7 or more. On the other hand, there is no particular upper limit to the number of carbon atoms in the alicyclic structure, but similarly, from the perspective of compatibility, it is preferably 15 or less, and particularly preferably 10 or less.

[0080] Specifically, examples of the aforementioned alicyclic monomers include cyclohexyl methacrylate, dicyclopentyl methacrylate, adamantyl methacrylate, isobornyl methacrylate, dicyclopentenyl methacrylate, and dicyclopentenyloxyethyl methacrylate. Among these, dicyclopentyl methacrylate (10 carbon atoms in the alicyclic structure), adamantyl methacrylate (10 carbon atoms in the alicyclic structure), or isobornyl methacrylate (7 carbon atoms in the alicyclic structure) are preferred for their superior step-following properties. Isobornyl methacrylate is particularly preferred, and isobornyl methacrylate is even more preferred. These alicyclic monomers can be used alone or in combination of two or more.

[0081] When the (meth)acrylate polymer (A) contains an alicyclic monomer as a monomer unit constituting the polymer, it is preferable to contain 1% or more by mass, particularly preferably 4% or more by mass, and even more preferably 8% or more of the alicyclic monomer. Furthermore, the (meth)acrylate polymer (A) preferably contains 30% or less by mass, particularly preferably 22% or less by mass, and even more preferably 14% or less of the alicyclic monomer as a monomer unit constituting the polymer. By keeping the content of the alicyclic monomer within the above ranges, the resulting adhesive exhibits superior step-following properties and anti-foaming properties, while also achieving better adhesion to plastics.

[0082] Furthermore, the aforementioned (meth)acrylate polymer (A) preferably contains a nitrogen-containing monomer as a monomeric unit constituting the polymer. By having a nitrogen-containing monomer present in the polymer as a structural unit, the adhesive can be endowed with a specified polarity, resulting in excellent affinity of the adhesive for adherends with a certain degree of polarity, such as glass. From the perspective of giving the (meth)acrylate polymer (A) suitable rigidity, the aforementioned nitrogen-containing monomer is preferably a monomer having a nitrogen-containing heterocycle. Furthermore, from the perspective of increasing the degree of freedom of the portion derived from the aforementioned nitrogen-containing monomer in the high-dimensional structure of the constructed adhesive, it is preferable that the nitrogen-containing monomer does not contain reactive unsaturated double bond groups, except for one polymerizable group used in the polymerization of the (meth)acrylate polymer (A). In addition, the aforementioned monomers containing reactive functional groups are not included in the nitrogen-containing monomers described herein.

[0083] Examples of monomers having nitrogen-containing heterocycles include N-(meth)acryloylmorpholine, N-vinyl-2-pyrrolidone, N-(meth)acryloylpyrrolidone, N-(meth)acryloylpiperidine, N-(meth)acryloylpyrrolidine, N-(meth)acryloylaziridine, acridinediethyl(meth)acrylate, 2-vinylpyridine, 4-vinylpyridine, 2-vinylpyrazine, 1-vinylimidazolium, N-vinylcarbazole, and N-vinylphthalimide. Among these, N-(meth)acryloylmorpholine, which exhibits superior adhesive properties, is preferred, and N-acryloylmorpholine is particularly preferred. These monomers having nitrogen-containing heterocycles can be used alone or in combination of two or more.

[0084] When the (meth)acrylate polymer (A) contains a nitrogen-containing monomer as a monomer unit constituting the polymer, it is preferable to contain 1% or more by mass, particularly preferably 4% or more by mass, and even more preferably 8% or more of the nitrogen-containing monomer. Furthermore, the (meth)acrylate polymer (A) preferably contains 20% or less by mass, particularly preferably 16% or less by mass, and even more preferably 12% or less of the nitrogen-containing monomer as a monomer unit constituting the polymer. If the content of the nitrogen-containing monomer is within the above range, the resulting adhesive can sufficiently exert excellent adhesion to glass.

[0085] The (meth)acrylate polymer (A) may also contain other monomers as constituent units of the polymer, as needed. To avoid hindering the aforementioned effects of monomers containing reactive functional groups, monomers without reactive functional groups are preferred as other monomers. Examples of such monomers include methoxyethyl methacrylate, ethoxyethyl methacrylate, alkoxyalkyl methacrylates, vinyl acetate, styrene, etc. These other monomers may be used alone or in combination of two or more.

[0086] The (meth)acrylate polymer (A) is preferably a linear polymer. Because making it a linear polymer makes it easier for the molecular chains to entangle with each other, and can be expected to improve cohesiveness, it is easy to obtain an adhesive with excellent step follow-through and anti-foaming properties under high temperature and high humidity conditions.

[0087] Furthermore, the (meth)acrylate polymer (A) is preferably a solution polymer obtained by solution polymerization. Since it is a solution polymer, it is easy to obtain a high molecular weight polymer and can be expected to improve cohesiveness, thus it is easy to obtain an adhesive with excellent step follow-through and anti-foaming properties under high temperature and high humidity conditions.

[0088] The polymerization form of (meth)acrylate polymer (A) can be a random copolymer or a block copolymer.

[0089] The lower limit of the weight-average molecular weight of the (meth)acrylate polymer (A) is preferably 200,000 or more, particularly preferably 300,000 or more, and even more preferably 400,000 or more. If the lower limit of the weight-average molecular weight of the (meth)acrylate polymer (A) is as described above, the resulting adhesive exhibits superior step-following properties and anti-foaming properties under high temperature and high humidity conditions.

[0090] Furthermore, the upper limit of the weight-average molecular weight of the (meth)acrylate polymer (A) is preferably 2 million or less, more preferably 1.5 million or less, particularly preferably 900,000 or less, and even more preferably 600,000 or less. If the upper limit of the weight-average molecular weight of the (meth)acrylate polymer (A) is as described above, the step-following performance of the resulting adhesive becomes even better. Additionally, the weight-average molecular weight in this specification is a value converted from standard polystyrene determined by gel permeation chromatography (GPC).

[0091] In addition, in the adhesive composition P, the (meth)acrylate polymer (A) can be used alone or in combination of two or more.

[0092] (1-2) Crosslinking agent (B)

[0093] The crosslinking agent (B) can crosslink the (meth)acrylate polymer (A) by heating the adhesive composition P, forming a good three-dimensional network structure. As a result, the cohesive strength of the adhesive is improved, and the step-following performance under high temperature and high humidity conditions becomes excellent.

[0094] As the aforementioned crosslinking agent (B), any agent that reacts with the reactive groups of the (meth)acrylate polymer (A) can be used. Examples include isocyanate crosslinking agents, epoxy crosslinking agents, amine crosslinking agents, melamine crosslinking agents, aziridine crosslinking agents, hydrazine crosslinking agents, aldehyde crosslinking agents, oxazoline crosslinking agents, metal alkoxide crosslinking agents, metal chelate crosslinking agents, metal salt crosslinking agents, and ammonium salt crosslinking agents. Among these, when the reactive group of the (meth)acrylate polymer (A) is a hydroxyl group, an isocyanate crosslinking agent with excellent reactivity with hydroxyl groups is preferred; when the reactive group of the (meth)acrylate polymer (A) is a carboxyl group, an epoxy crosslinking agent with excellent reactivity with carboxyl groups is preferred. Furthermore, crosslinking agent (B) can be used alone or in combination of two or more.

[0095] Isocyanate crosslinking agents contain at least a polyisocyanate compound. Examples of polyisocyanate compounds include aromatic polyisocyanates such as toluene diisocyanate, diphenylmethane diisocyanate, and phthalimide diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate; isophorone diisocyanate; hydrogenated diphenylmethane diisocyanate; and alicyclic polyisocyanates such as their biuret forms, isocyanurate forms, and adducts as reactants with low-molecular-weight compounds containing active hydrogen, such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil. From the perspective of reactivity with hydroxyl groups, trimethylolpropane-modified aromatic polyisocyanates are preferred, and trimethylolpropane-modified toluene diisocyanate and trimethylolpropane-modified phthalimide diisocyanate are particularly preferred.

[0096] Examples of epoxy crosslinking agents include 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-m-xylenediamine, ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidyl aniline, and diglycidylamine. Among these, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane is preferred from the perspective of its reactivity with carboxyl groups.

[0097] The content of crosslinking agent (B) in the adhesive composition P is preferably 0.01 parts by mass or more, more preferably 0.03 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 (meth)acrylate polymer (A). Furthermore, this 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, even more preferably 0.4 parts by mass or less, and most preferably 0.25 parts by mass or less. By keeping the content of crosslinking agent (B) within the above range, the resulting adhesive exhibits good cohesiveness, and the step-following performance under high temperature and high humidity conditions becomes even more excellent.

[0098] (1-3) Active energy ray curing component (C)

[0099] In the cured adhesive (the adhesive constituting the cured adhesive layer) obtained by curing the adhesive formed by crosslinking the adhesive composition P of this embodiment with active energy rays, it is presumed that the active energy ray curable component (C) polymerizes with each other, and the polymerized active energy ray curable component (C) is wrapped around the crosslinked structure (three-dimensional network structure) of the (meth)acrylate polymer (A). The adhesive having this high-dimensional structure exhibits very excellent durability, and its step follow-through and anti-foaming properties under high temperature and high humidity conditions become particularly excellent.

[0100] The active energy ray curable component (C) is not particularly limited as long as it is a component that is cured by irradiation with active energy rays to achieve the above-mentioned effect. It can be any one of monomers, oligomers, or polymers, or a mixture of these substances. Among them, multifunctional acrylate monomers with better anti-foaming properties are preferred.

[0101] Examples of multifunctional acrylate monomers include 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, neopentyl adipate di(meth)acrylate, neopentyl hydroxypentyl adipate di(meth)acrylate, dicyclopentyl di(meth)acrylate, tricyclodecanediethanol (meth)acrylate, caprolactone-modified dicyclopentenyl di(meth)acrylate, ethylene oxide-modified di(meth)acrylate phosphate, di(acryloyloxyethyl)isocyanurate, allylated cyclohexyl di(meth)acrylate, ethoxylated bisphenol A diacrylate, and 9,9-bis[4-(2-acryloyloxy] [Ethoxy]phenyl]fluorene and other bifunctional monomers; trifunctional monomers such as trimethylolpropane tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, propionic acid-modified dipentaerythritol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propylene oxide-modified trimethylolpropane tri(meth)acrylate, tri(acryloyloxyethyl)isocyanurate, ε-caprolactone-modified tri(2-(meth)acryloyloxyethyl)isocyanurate; tetrafunctional monomers such as diglycerol tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate; pentafunctional monomers such as propionic acid-modified dipentaerythritol penta(meth)acrylate; and hexafunctional monomers such as dipentaerythritol hexa(meth)acrylate, caprolactone-modified dipentaerythritol hexa(meth)acrylate, etc. These multifunctional acrylate monomers can be used alone or in combination of two or more. Furthermore, from the perspective of compatibility with (meth)acrylate polymer (A), the molecular weight of the multifunctional acrylate monomer is preferably less than 1000.

[0102] From the perspective of the anti-foaming properties of the obtained adhesive, polyfunctional acrylate monomers containing an isocyanurate structure in the molecule, such as di(acryloyloxyethyl)isocyanurate, tri(acryloyloxyethyl)isocyanurate, and ε-caprolactone-modified tri(2-(meth)acryloyloxyethyl)isocyanurate, are preferred; or polyfunctional acrylate monomers containing a cyclic structure (especially a cycloalkane structure), such as tricyclodecanediethanol (meth)acrylate, are preferred. More preferably, these monomers are trifunctional or higher and contain isocyanate in the molecule. The monomers are polyfunctional acrylate monomers with a urea ester structure, or polyfunctional acrylate monomers with a degree of difunctionality or higher and containing a polycyclic structure (especially a polycyclic structure of cycloalkanes) within the molecule. ε-caprolactone-modified tris(2-(meth)acryloyloxyethyl)isocyanurate or tricyclodecanediethanol (meth)acrylate are particularly preferred, ε-caprolactone-modified tris(2-acryloyloxyethyl)isocyanurate or tricyclodecanediethanol acrylate are even more preferred, and ε-caprolactone-modified tris(2-acryloyloxyethyl)isocyanurate is the most preferred.

[0103] From the perspective of improving the anti-foaming properties of the cured adhesive, the lower limit of the content of the active energy ray curable component (C) in the adhesive composition P relative to 100 parts by mass of (meth)acrylate polymer (A) is preferably 1 part by mass or more, particularly preferably 3 parts by mass or more, and even more preferably 4 parts by mass or more. On the other hand, from the perspective of the adhesion of the cured adhesive, as well as the step follow-through and anti-foaming properties under high temperature and high humidity conditions, the upper limit of the above content is preferably 20 parts by mass or less, particularly preferably 12 parts by mass or less, and even more preferably 8 parts by mass or less.

[0104] (1-4) Colorant (D)

[0105] The colorant (D) is the colorant described above. The specific type or content in the adhesive is the same as described above.

[0106] The content of colorant (D) relative to 100 parts by weight of (meth)acrylate polymer (A) is preferably 0.01 parts by weight or more, more preferably 0.05 parts by weight or more, particularly preferably 0.1 parts by weight or more, and even more preferably 0.15 parts by weight or more. Furthermore, the above-mentioned content is preferably 2 parts by weight or less, more preferably 1 part by weight or less, particularly preferably 0.5 parts by weight or less, and even more preferably 0.2 parts by weight or less.

[0107] (1-5) Photopolymerization initiator (E)

[0108] When using ultraviolet light as the active energy ray for curing the adhesive composition P, it is preferable that the adhesive composition P further contains a photopolymerization initiator (E). By containing a photopolymerization initiator (E) in this way, the active energy ray curable component (C) can be effectively polymerized, and in addition, the polymerization and curing time and the amount of active energy ray irradiation can be reduced.

[0109] Examples of photopolymerization initiators (E) include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropane-1-one, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-1-one, 4-(2-hydroxyethoxy)phenyl-2-(hydroxy-2-propyl)one, benzophenone, and p-phenylbenzene. Ketones, 4,4'-diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzoyl dimethyl ketal, acetophenone dimethyl ketal, p-dimethylaminobenzoate, oligomer [2-hydroxy-2-methyl-1[4-(1-methylvinyl)phenyl]acetone], 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, etc. These photopolymerization initiators can be used alone or in combination of two or more.

[0110] Among the above, phosphine oxide-based photopolymerization initiators are preferred because they readily decompose even when exposed to ultraviolet light through a plastic sheet containing an ultraviolet absorber, thus ensuring reliable curing of the adhesive. Specifically, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide are preferred.

[0111] The lower limit of the content of photopolymerization initiator (E) in the adhesive composition P relative to 100 parts by mass of the active energy ray curable component (C) is preferably 0.1 parts by mass or more, particularly preferably 1 part by mass or more, and even more preferably 5 parts by mass or more. Furthermore, the upper limit is preferably 30 parts by mass or less, particularly preferably 20 parts by mass or less, and even more preferably 12 parts by mass or less.

[0112] The mass ratio of the amount of photopolymerization initiator (E) to the amount of colorant (D) (photopolymerization initiator (E) / colorant (D)) is preferably 0.5 or more, particularly preferably 1 or more, and even more preferably 2 or more. Furthermore, the above ratio is preferably 20 or less, more preferably 12 or less, particularly preferably 8 or less, and even more preferably 4 or less. By keeping the ratio of the amount of photopolymerization initiator (E) to the amount of colorant (D) within the above range, the total light transmittance or lightness L* can be suitable, and an adhesive with suitable cohesiveness or adhesion can be easily obtained by curing with active energy rays, and the anti-foaming properties can be further improved.

[0113] (1-6) Various additives

[0114] Various additives commonly used in acrylic adhesives, such as silane coupling agents, rust inhibitors, UV absorbers, antistatic agents, tackifiers, antioxidants, light stabilizers, softeners, and refractive index modifiers, can be added to the adhesive composition P as needed. Furthermore, the polymerization solvents or diluting solvents described below are not included in the additives constituting the adhesive composition P.

[0115] In the above-mentioned adhesive composition P, it is preferable to contain a silane coupling agent. As a result, the adhesion to the adhered object is improved, regardless of whether the adhered object is a plastic sheet or a glass component, and the step follow-through and anti-foaming properties under high temperature and high humidity conditions are also improved.

[0116] As a silane coupling agent, an organosilicon compound that is well compatible with (meth)acrylate polymer (A), has light transmittance, and has at least one alkoxysilyl group in the molecule is preferred.

[0117] Examples of silane coupling agents include, for example, silicon compounds containing polymerizable unsaturated groups such as vinyltrimethoxysilane, vinyltriethoxysilane, and methacryloyloxypropyltrimethoxysilane; silicon compounds with epoxy structures such as 3-glycidyl etheroxypropyltrimethoxysilane and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; and mercapto-containing compounds such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, and 3-mercaptopropyldimethoxymethylsilane. These silane coupling agents include: silane compounds containing amino groups such as 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, and N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane; and condensates of 3-chloropropyltrimethoxysilane, propyltriethoxysilane, or at least one thereof with alkyl-containing silicon compounds such as methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, and ethyltrimethoxysilane. These silane coupling agents can be used alone or in combination of two or more.

[0118] The content of silane coupling agent in the 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 0.08 parts by mass or more, relative to 100 parts by mass of the (meth)acrylate polymer (A). Furthermore, this content is 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.

[0119] (2) Preparation of adhesive composition

[0120] The adhesive composition P can be prepared by preparing a (meth)acrylate polymer (A), mixing the obtained (meth)acrylate polymer (A), a crosslinking agent (B), an active energy ray curable component (C), and a colorant (D), while adding additives as needed.

[0121] (Meth)acrylate polymer (A) can be prepared by polymerizing a mixture of monomers constituting the polymer using conventional free radical polymerization. Preferably, the polymerization of (meth)acrylate polymer (A) is carried out by solution polymerization using a polymerization initiator as needed. Examples of polymerization solvents include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone, etc., and two or more can be used simultaneously.

[0122] Examples of polymerization initiators include azo compounds and organic peroxides, and more than one type can be used simultaneously. Examples of azo compounds include 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane-1-carboxylonitrile), 2,2'-azobis(2,4-dimethylpentanonitrile), 2,2'-azobis(2,4-dimethyl-4-methoxypentanonitrile), dimethyl 2,2'-azobis(2-methylpropionate), 4,4'-azobis(4-cyanopentanoic acid), 2,2'-azobis(2-hydroxymethylpropionitrile), and 2,2'-azobis[2-(2-imidazolin-2-yl)propane].

[0123] Examples of organic peroxides include benzoyl peroxide, tert-butyl peroxide, cumene hydroperoxide, diisopropyl peroxide, di-n-propyl peroxide, di(2-ethoxyethyl) peroxide, tert-butyl peroxydecanoate, tert-butyl peroxypentanoate, (3,5,5-trimethylhexanoyl peroxide), dipropionyl peroxide, and diacetyl peroxide.

[0124] Furthermore, in the above polymerization process, the weight-average molecular weight of the obtained polymer can be adjusted by incorporating chain transfer agents such as 2-mercaptoethanol.

[0125] After obtaining (meth)acrylate polymer (A), a crosslinking agent (B), an active energy ray curable component (C), a colorant (D), and a diluent and additives as required are added to a solution of (meth)acrylate polymer (A), and the mixture is thoroughly mixed to obtain a solvent-diluted adhesive composition P (coating solution). Furthermore, for any of the above components, if precipitation occurs when using a solid substance or when mixed with other components in an undiluted state, that component can be dissolved or diluted separately in a diluent before mixing with the other components.

[0126] As diluents for the above-mentioned purposes, aliphatic hydrocarbons such as hexane, heptane, and cyclohexane; aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as dichloromethane and vinyl 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 cellosol solvents such as ethyl cellosol.

[0127] The concentration and viscosity of the coating solution prepared in this manner are not particularly limited as long as they are within a coatable range and can be appropriately selected according to the situation. For example, the adhesive composition P can be diluted to a concentration of 10-60% by mass. Furthermore, adding a diluent is not necessary when obtaining the coating solution; as long as the adhesive composition P has a coatable viscosity, a diluent may not be added. In this case, the adhesive composition P is a coating solution in which the polymerization solvent of the (meth)acrylate polymer (A) is used directly as the diluent.

[0128] (3) Formation of adhesive layer

[0129] Preferably, the adhesive layer 11 in this embodiment is composed of an adhesive formed from a crosslinked adhesive composition P (coating layer). Crosslinking of the adhesive composition P can usually be performed by heat treatment. Alternatively, the drying process that causes the diluent or the like to evaporate from the coating layer of the adhesive composition P applied to the desired object can also be used as the heat treatment.

[0130] The heating temperature for the heat treatment is preferably 50–150°C, and more preferably 70–120°C. Furthermore, the heating time is preferably 10 seconds to 10 minutes, and more preferably 50 seconds to 2 minutes.

[0131] After heat treatment, a curing period of approximately 1 to 2 weeks can be set at room temperature (e.g., 23°C, 50% RH) as needed. If this curing period is required, the adhesive will form after the curing period; if no curing period is required, the adhesive will form directly after the heat treatment is completed.

[0132] Through the aforementioned heat treatment (and aging), the (meth)acrylate polymer (A) is fully crosslinked via the crosslinking agent (B). The adhesive obtained in this manner exhibits excellent step-following properties under high temperature and high humidity conditions.

[0133] (4) Properties of adhesives

[0134] The lower limit of the gel fraction of the adhesive in this embodiment is preferably 20% or more, more preferably 30% or more, particularly preferably 40% or more, and even more preferably 45% or more. If the lower limit of the gel fraction of the adhesive is as described above, the cohesive strength of the adhesive increases, and the step follow-through under high temperature and high humidity conditions becomes more excellent. Furthermore, the upper limit of the gel fraction of the adhesive in this embodiment is preferably 90% or less, more preferably 80% or less, particularly preferably 70% or less, and even more preferably 60% or less. If the upper limit of the gel fraction of the adhesive is as described above, the adhesive does not become too hard, and both the initial step follow-through and the durable step follow-through become excellent. In addition, good adhesion is exhibited, and the adhesion to the adhered object becomes more excellent. Here, the method for determining the gel fraction of the adhesive is as shown in the experimental examples described later.

[0135] (5) Thickness of adhesive layer

[0136] Preferably, the thickness (Z μm) of the adhesive layer 11 of the adhesive sheet 1 in this embodiment is a value that satisfies the above-mentioned formula (I) for X×Z.

[0137] Specifically, the minimum thickness of the adhesive layer 11 is preferably 25 μm or more, and more preferably 40 μm or more. If the minimum thickness of the adhesive layer 11 is as described above, then due to its relationship with the content of the colorant (D), the aforementioned total transmittance and lightness L* (as well as chromaticity a* and b* and haze value) are easily satisfied, and the required adhesion is easily achieved. Furthermore, from the perspective of easily achieving excellent step followability and anti-foaming properties, the minimum thickness is preferably 50 μm or more, and more preferably 75 μm.

[0138] The above is particularly preferred to be 100 μm or more, and even more preferably 120 μm or more.

[0139] Furthermore, the upper limit of the thickness of the adhesive layer 11 is preferably 1000 μm or less, more preferably 500 μm or less, particularly preferably 300 μm or less, and even more preferably 250 μm or less. If the upper limit of the thickness of the adhesive layer 11 is as described above, the processability becomes good. Furthermore, appearance defects caused by extrusion marks are less likely to occur. Furthermore, due to the relationship with the content of the colorant (D), the above-mentioned total light transmittance and lightness L* (as well as chromaticity a* and b* and haze value) are easily satisfied. In addition, the adhesive layer 11 can be formed as a single layer or as multiple layers stacked together.

[0140] 1-2. Peeling sheet

[0141] Release tabs 12a and 12b protect the adhesive layer 11 until it is peeled off when the adhesive sheet 1 (adhesive layer 11) is used. In the adhesive sheet 1 of this embodiment, one or both of the release tabs 12a and 12b are not necessarily required.

[0142] As release sheets 12a and 12b, for example, polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polyethylene naphthalate film, polybutylene terephthalate film, polyurethane film, ethylene-vinyl acetate film, ionomer resin film, ethylene-(meth)acrylate copolymer film, ethylene-(meth)acrylate copolymer film, polystyrene film, polycarbonate film, polyimide film, fluoropolymer film, etc. Furthermore, cross-linked films of these films can also be used. Further, laminated films of these films can also be used.

[0143] It is preferable to perform a peeling treatment on the peeling surfaces (particularly the surfaces in contact with the adhesive layer 11) of the aforementioned release sheets 12a and 12b. Examples of release agents used for the peeling treatment include alkyd, silicone, fluorinated, unsaturated polyester, polyolefin, and paraffin-based release agents. Furthermore, among the release sheets 12a and 12b, it is preferable to designate one release sheet as a heavy-duty release sheet with high peeling force and the other as a light-duty release sheet with low peeling force.

[0144] There are no particular restrictions on the thickness of the release strips 12a and 12b, but they are usually around 20 to 150 μm.

[0145] 2. Manufacturing of adhesive sheets

[0146] As an example of manufacturing the adhesive sheet 1, a coating solution of the adhesive composition P is applied to the release surface of a release sheet 12a (or 12b), and then heat-treated to thermally crosslink the adhesive composition P to form a coating layer. Then, the release surface of another release sheet 12b (or 12a) is laminated onto this coating layer. If a curing period is required, the coating layer becomes the adhesive layer 11 by setting a curing period; otherwise, the coating layer directly becomes the adhesive layer 11. Thus, the adhesive sheet 1 is obtained. The heat treatment and curing conditions are as described above.

[0147] As another manufacturing example of the adhesive sheet 1, a coating solution of the adhesive composition P is applied to the release surface of a release sheet 12a, and heat treatment is performed to thermally crosslink the adhesive composition P, forming a coating layer, thus obtaining a release sheet 12a with a coating layer. Furthermore, a coating solution of the adhesive composition P is applied to the release surface of another release sheet 12b, and heat treatment is performed to thermally crosslink the adhesive composition P, forming a coating layer, thus obtaining a release sheet 12b with a coating layer. Then, the release sheets 12a and 12b with coating layers are bonded together in such a way that the two coating layers are in contact with each other. Here, multiple release sheets with coating layers can be manufactured, and the required number of coating layers can be bonded together. When a curing period is required, by setting a curing period, the stacked coating layers become the adhesive layer 11; when a curing period is not required, the stacked coating layers directly become the adhesive layer 11. Thus, the adhesive sheet 1 is obtained. According to this manufacturing example, manufacturing can be carried out stably even when the adhesive layer 11 is relatively thick.

[0148] Methods for applying the coating solution of the adhesive composition P can include, for example, rod coating, blade coating, roller coating, scraper coating, die coating, gravure coating, etc.

[0149] [Display Body]

[0150] Examples of display bodies (displays) used in this embodiment include in-vehicle displays installed in various gauges on car dashboards, car navigation systems, and control consoles; displays for general user tablet terminals; displays for commercial tablet terminals or digital signage; and displays for outdoor digital signage. Sometimes, these displays are required to have aesthetic harmony with surrounding components or a sense of sophistication. However, the display body of the present invention is not limited to these.

[0151] like Figure 2 As shown, 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 a cured adhesive layer 11'. The cured adhesive layer 11' is located between the first display body component 21 and the second display body component 22, and adheres the first display body component 21 and the second display body component 22 to each other.

[0152] At least one of the first display body component 21 and the second display body component 22 may have a step on at least one side of the surface where the cured adhesive layer 11' is adhered. Figure 2 In the embodiment shown, the first display body component 21 has a stepped surface such as a printed layer 3 on the surface of the cured adhesive layer 11' side.

[0153] The cured adhesive layer 11' in the aforementioned display body 2 is cured by irradiating the adhesive layer 11 of the aforementioned adhesive sheet 1 with active energy rays. When an adhesive composition P is used in the formation of the adhesive layer 11, the cured adhesive constituting the cured adhesive layer 11' has a cross-linked structure composed of a (meth)acrylate polymer (A) and a cross-linking agent (D), and also contains a cured product (polymer) containing an active energy ray curable component (C), and may further contain a photopolymerization initiator (E) and additives, depending on the situation. It is presumed that the active energy ray curable component (C) polymerizes to form a three-dimensional network structure with a certain degree of coarsening of the mesh, while simultaneously intertwining with the aforementioned cross-linked structure to form a high-dimensional structure. This structure provides excellent anti-foaming properties.

[0154] Furthermore, the photopolymerization initiator (E) contained in the cured adhesive layer 11' is a photopolymerization initiator (E) contained in the adhesive composition P that does not decompose and remains even when irradiated with active energy rays. Therefore, its content is low, typically 0.00001% by mass or more and 0.1% by mass or less in the adhesive, preferably 0.0001% by mass or more and 0.01% by mass or less.

[0155] After curing, the thickness of the adhesive layer 11' is basically the same as the thickness of the adhesive layer 11 of the adhesive sheet 1.

[0156] The lower limit of the gel fraction of the cured adhesive constituting the cured adhesive layer 11' is preferably 55% or more, more preferably 60% or more, particularly preferably 65% ​​or more, and even more preferably 67% or more. If the lower limit of the gel fraction of the cured adhesive is as described above, the anti-foaming properties of the cured adhesive layer 11' become even more excellent. Furthermore, the upper limit of the gel fraction of the cured adhesive is preferably 95% or less, more preferably 90% or less, particularly preferably 80% or less, and even more preferably 74% or less. If the upper limit of the gel fraction of the cured adhesive is as described above, the adhesive strength, step follow-through under high temperature and high humidity conditions, and anti-foaming properties of the cured adhesive layer 11' become even more excellent. The method for determining the gel fraction of the cured adhesive is shown in the test examples described below.

[0157] The lower limit of the adhesion force of the cured adhesive layer 11' to the soda-lime glass is preferably 10 N / 25 mm or more, more preferably 20 N / 25 mm or more, more preferably 30 N / 25 mm or more, particularly preferably 40 N / 25 mm or more, and even more preferably 50 N / 25 mm or more. If the lower limit of the adhesion force is as described above, the step follow-through and anti-bubbling properties under high temperature and high humidity conditions become more excellent. In addition, the upper limit of the adhesion force is not particularly limited, but it is preferably 100 N / 25 mm or less, more preferably 80 N / 25 mm or less, and particularly preferably 60 N / 25 mm or less.

[0158] Here, the adhesion force in this specification refers to the adhesion force measured in accordance with the 180-degree peel method of JIS Z0237:2009. The test sample is made into a sample that is 25 mm wide and 100 mm long. The test sample is attached to the object to be adhered to, and then pressure is applied at 0.5 MPa and 50°C for 20 minutes. After that, it is placed under normal pressure, 23°C and 50% RH for 24 hours. The value is then measured at a peeling speed of 300 mm / min.

[0159] As a display body 2, examples include liquid crystal (LCD) displays, light-emitting diode (LED) displays, organic electroluminescent (OLED) displays, electronic paper, etc., and it can also be a touch panel.

[0160] Besides glass plates, plastic plates, etc., the first display body component 21 is preferably a protective panel made of a laminate containing glass plates, plastic plates, etc., and is particularly preferably a protective panel made of plastic plates or a laminate containing plastic plates. In this case, the printed layer 3 is usually formed in a frame shape on the adhesive layer 11' side after the first display body component 21 has cured.

[0161] The glass plate mentioned above is not particularly limited, and examples include chemically strengthened glass, alkali-free glass, quartz glass, soda-lime glass, barium-strontium glass, aluminosilicate glass, lead glass, borosilicate glass, and barium borosilicate glass. The thickness of the glass plate is not particularly limited, but is typically 0.1–5 mm, preferably 0.2–2 mm.

[0162] When plastic sheets are placed at high temperatures, such as 85°C, the low-boiling-point components inside vaporize, which may cause blistering, lifting, or peeling at the interface between the plastic sheet and the cured adhesive layer 11'. However, even with such a plastic sheet, the display body 2 of this embodiment can effectively suppress blistering by using the adhesive composition P in the formation of the adhesive layer 11'.

[0163] The type of plastic sheet is not particularly limited; examples include polycarbonate (PC) sheets, polymethyl methacrylate (PMMA) sheets, and other acrylic resin sheets, as well as plastic sheets with polymethyl methacrylate layers or other acrylic resin layers laminated on polycarbonate sheets. Furthermore, the aforementioned polycarbonate sheets may also contain resins other than polycarbonate resin as constituent materials, and similarly, the aforementioned acrylic resin sheets may contain resins other than acrylic resin as constituent materials. Additionally, ultraviolet absorbers may be added to the plastic sheet.

[0164] The thickness of the plastic sheet is not particularly limited, but it is usually 0.2 to 5 mm, preferably 0.4 to 3 mm, particularly preferably 0.6 to 2.5 mm, and even more preferably 1 to 2.1 mm.

[0165] Various functional layers (transparent conductive film, metal layer, silicon dioxide layer, hard coating, anti-glare layer, etc.) can be applied to one or both sides of the aforementioned glass or plastic plate, and optical components can also be stacked. In addition, the transparent conductive film and metal layer can also be patterned.

[0166] The second display component 22 is preferably an optical component, a display module (e.g., a liquid crystal (LCD) module, a light-emitting diode (LED) module, an organic electroluminescent (organic EL) module, an optical component that is part of the display module, or a laminate containing a display module that should be attached to the first display component 21.

[0167] Examples of the aforementioned optical components include anti-spray films, polarizers (polarizing films), polarizers, retardation plates (retardation films), viewing angle compensation films, brightness enhancement films, contrast enhancement films, liquid crystal polymer films, diffusion films, semi-transparent reflective films, and transparent conductive films. Examples of anti-spray films include hard coating films formed by forming a hard coating on one side of a substrate film.

[0168] The material constituting the printing layer 3 is not particularly limited, and commonly known printing materials can be used.

[0169] The thickness of the printed 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 to the above-mentioned value, sufficient concealment of electrical wiring and the like can be ensured from the observer's side. Furthermore, 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 to the above-mentioned value or less, the step follower of the adhesive layer 11' to the printed layer 3 after curing can be prevented from deteriorating.

[0170] In order to manufacture the above-mentioned display body 2, as an example, a release piece 12a of the adhesive sheet 1 is peeled off, and the adhesive layer 11 exposed by the adhesive sheet 1 is attached to the side of the first display body constituent member 21 where the printed layer 3 is present.

[0171] Next, another release tab 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 to obtain a laminate. Furthermore, as another example, the bonding order of the first display body component 21 and the second display body component 22 can be changed.

[0172] Then, the adhesive layer 11 in the above-mentioned laminate is irradiated with active energy rays. As a result, the energy-curing component (C) in the adhesive layer 11 polymerizes, and the adhesive layer 11 is cured to become the cured adhesive layer 11'. The irradiation of the adhesive layer 11 with energy rays is usually performed through either the first display body constituent member 21 or the second display body constituent member 22, preferably through the first display body constituent member 21 which serves as a protective panel.

[0173] Here, active energy rays refer to active energy rays that possess energy quanta within electromagnetic waves or charged particle beams; specifically, examples include ultraviolet light or electron beams. Among active energy rays, ultraviolet light, which is easily manipulated, is particularly preferred.

[0174] Ultraviolet (UV) irradiation can be performed using high-pressure mercury lamps, fusion H lamps, xenon lamps, etc. The UV irradiation dose, measured in illuminance, is preferably 50–1000 mW / cm². 2 The optimal value is approximately 100–500 mW / cm². 2 Approximately. Furthermore, the preferred light intensity is 50–10000 mJ / cm². 2 More preferably, it is 200–7000 mJ / cm². 2 The preferred value is 500–3000 mJ / cm³. 2 On the other hand, electron beam irradiation can be performed using an electron beam accelerator or the like, and the preferred irradiation dose is approximately 10 to 1000 krad.

[0175] like Figure 3As shown, in this preferred embodiment, the display body 2 has a frame 4 around its perimeter. Preferably, the frame 4 is black. Furthermore, the preferred ranges for the lightness L*, chromaticity a*, and chromaticity b* of the frame 4, as defined by the CIE 1976 L*a*b* color system, are the same as the colors of the surrounding components. By giving the frame 4 this color, it is easily recognized by the naked eye as a frame with a high-end visual appeal. Furthermore, by giving the frame 4 the aforementioned color, the overall integration of the cured adhesive layer 11' and the frame 4 in this embodiment is enhanced, resulting in better harmony.

[0176] By incorporating the physical properties (total light transmittance, brightness L*, etc.) of the adhesive layer 11 after curing, the display body 2 is given an overall feel to the black frame 4, resulting in excellent aesthetic harmony. Furthermore, the display body 2 ensures its visibility as a display.

[0177] Furthermore, in the above-mentioned display body 2, when the adhesive layer 11 is formed by the adhesive composition P, the step follower of the cured adhesive layer 11' under high temperature and high humidity conditions is excellent. Therefore, even when the display body 2 is placed under high temperature and high humidity conditions (e.g., 85°C, 85%RH), it is possible to suppress the occurrence of bubbles, floating, peeling, etc. near the step.

[0178] Furthermore, in the aforementioned display body 2, when the adhesive layer 11 is formed from the adhesive composition P, the cured adhesive layer 11' exhibits excellent anti-foaming properties. Therefore, even when the display body 2 is placed under high temperature and high humidity conditions (e.g., 85°C, 85% RH) and degassing occurs from the first display body component 21 and / or the second display body component 22, it is possible to suppress bubbling, floating, peeling, and other bubbling at the interface between the cured adhesive layer 11' and the display body component 21, 22.

[0179] The embodiments described above are provided for ease of understanding of the present invention and are not intended to limit the present invention. Therefore, the elements disclosed in the above embodiments also cover all design changes or equivalents that fall within the technical scope of the present invention.

[0180] For example, one or both of the release tabs 12a and 12b in the adhesive sheet 1 can be omitted. Alternatively, the required optical components can be laminated to replace the release tabs 12a and / or 12b. Furthermore, the first display body component 21 may not have a step. Moreover, not only the first display body component 21, but also the second display body component 22 may have a step on the adhesive layer 11' side after curing.

[0181] Example

[0182] The present invention will be further described in detail below through examples, etc., but the scope of the present invention is not limited by these examples, etc.

[0183] [Example 1]

[0184] 1. Preparation of (meth)acrylate polymers

[0185] (Meth)acrylate polymer (A) was prepared by solution polymerization of 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. The molecular weight of (meth)acrylate polymer (A) was determined using the method described below, and the weight-average molecular weight (Mw) was 500,000.

[0186] 2. Preparation of adhesive compositions

[0187] The following ingredients are used: 100 parts by weight (solid content conversion value; the same applies below) of the (meth)acrylate polymer (A) obtained in step 1 above; 0.2 parts by weight of trimethylolpropane-modified toluene diisocyanate (manufactured by TOYOCHEM CO.,LTD., product name "BHS8515") as a crosslinking agent (B); 5.0 parts by weight of ε-caprolactone-modified tris(2-acryloyloxyethyl)isocyanurate (C1: SHIN-NAKAMURACHEMICAL CO.,LTD., product name "NK EsterA-9300-1CL") as an active energy ray curing component (C); and 0.08 parts by weight of carbon black pigment (manufactured by TOYOCOLOR CO.,LTD., "Multilac") as a colorant (D). The mixture of 0.5 parts by mass of a 1:1 mixture of 1-hydroxycyclohexylphenyl ketone and benzophenone as photopolymerization initiators (E) (E1) and 0.1 parts by mass of 3-glycidyl etheroxypropyltrimethoxysilane as a silane coupling agent is stirred thoroughly and diluted with methyl ethyl ketone to obtain a coating solution of the adhesive composition.

[0188] Here, Table 1 shows the proportions (converted to solids content) of the adhesive composition when the (meth)acrylate polymer (A) is set at 100 parts by mass. Furthermore, the mass ratio (photopolymerization initiator (E) / colorant (D)) of the photopolymerization initiator (E) is calculated and shown in Table 1. Details of the abbreviations, etc., listed in Table 1 are as follows.

[0189] [(Meth)acrylate polymer (A)]

[0190] 2EHA: 2-Ethylhexyl acrylate

[0191] IBXA: Isoborneol Acrylate

[0192] ACMO: N-Acryloylmorpholine

[0193] HEA: 2-Hydroxyethyl acrylate

[0194] MMA: Methyl methacrylate

[0195] BA: n-Butyl acrylate

[0196] AA: Acrylic acid

[0197] [Crosslinking agent (B)]

[0198] TDI: Trimethylolpropane-modified toluene diisocyanate (manufactured by TOYOCHEM CO.,LTD., product name "BHS8515")

[0199] XDI: Trimethylolpropane-modified diphenylmethylene diisocyanate (manufactured by Soken Chemical & Engineering Co., Ltd., product name "TD-75")

[0200] Epoxy: 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane (manufactured by MITSUBISHI GAS CHEMICAL COMPANY, INC., product name "TETRAD-C")

[0201] [Active Energy Ray Curing Component (C)]

[0202] C1: ε-caprolactone-modified tris(2-acryloyloxyethyl) isocyanurate (manufactured by SHIN-NAKAMURA CHEMICALCO.,LTD., product name "NK Ester A-9300-1CL")

[0203] C2: Tricyclodecanediethanol diacrylate

[0204] [Coloring agent (D)]

[0205] Pigment: Carbon black pigment (manufactured by TOYOCOLOR CO.,LTD., "Multilac black")

[0206] Dye: Aniline black dye (manufactured by Orient Chemical Industries Co., Ltd., product name "NUBIANBLACK PA-2802")

[0207] [Photopolymerization initiator (E)]

[0208] E1: A mixture of 1-hydroxycyclohexylphenyl ketone and benzophenone in a 1:1 mass ratio. E2: 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide.

[0209] 3. Manufacturing of adhesive sheets

[0210] Using a doctor blade coater, the coating solution of the adhesive composition obtained in step 2 above is coated onto a heavy-release sheet (manufactured by LINTEC Corporation, product name) that has undergone single-sided peeling treatment of the polyethylene terephthalate film using a silicone-based release agent.

[0211] The coating layer ("SP-PET752150") is then heated at 90°C for 1 minute to form a coating layer (thickness: 25μm), thereby producing a re-peelable release sheet with a coating layer.

[0212] On the other hand, using a doctor blade coating machine, the coating solution of the adhesive composition obtained in step 2 above is coated onto a light-release sheet (manufactured by LINTEC Corporation, product name) that has undergone single-sided peeling treatment of the polyethylene terephthalate film using a silicone-based release agent.

[0213] The coating layer ("SP-PET382120") is then heated at 90°C for 1 minute to form a coating layer (thickness: 25μm), thereby producing 4 light-release peel sheets with the coating layer.

[0214] The coated layer side of the heavy-release peeling sheet with the coating layer obtained above is bonded to the coated layer side of one of the light-release peeling sheets with the coating layer obtained above, to obtain a first laminate with a coating layer of 50 μm thickness sandwiched between the heavy-release peeling sheet and the light-release peeling sheet.

[0215] Next, the light-release peeler is peeled off from the first laminate, and the exposed surface of the coating layer is bonded to the coating layer side of one of the light-release peelers with the coating layer, resulting in a second laminate with a coating layer of 75 μm thickness sandwiched between the heavy-release peeler and the light-release peeler. The same process is repeated to obtain a fourth laminate with a coating layer of 125 μm thickness sandwiched between the heavy-release peeler and the light-release peeler.

[0216] Then, the above fourth layer is cured at 23°C and 50% RH for 7 days to produce an adhesive sheet consisting of a heavy-release release sheet / adhesive layer (thickness: 125 μm) / light-release release sheet.

[0217] In addition, the thickness of the adhesive layer mentioned above is a value measured according to JIS K7130 using a constant pressure thickness measuring instrument (manufactured by TECLOCK CO.,LTD., product name "PG-02").

[0218] [Examples 2-11, Comparative Examples 1-2, Reference Example 1]

[0219] Except for changing the types and proportions of the monomers constituting the (meth)acrylate polymer (A), the weight-average molecular weight (Mw) of the (meth)acrylate polymer (A), the type and amount of crosslinking agent (B), the type and amount of active energy radiation curable component (C), the type and amount of colorant (D), the type and amount of photopolymerization initiator (E), and the amount of silane coupling agent as shown in Table 1, the adhesive sheet was manufactured in the same manner as in Example 1.

[0220] Here, the content of colorant in the adhesive layer (adhesive composition) formed in the Examples, Comparative Examples, and Reference Examples is set as X% by mass, and the thickness of the adhesive layer is set as Z μm. X×Z is calculated. The results are shown in Table 1.

[0221] The above weight-average molecular weight (Mw) is the weight-average molecular weight converted from polystyrene determined using gel permeation chromatography (GPC) under the following conditions (GPC determination).

[0222] <Measurement Conditions>

[0223] • GPC measuring apparatus: Manufactured by TOSOH CORPORATION, HLC-8020

[0224] • GPC column (passes through in the following order): TOSOH CORPORATION manufactured TSKguard column HXL-H

[0225] TSKgel GMHXL (×2)

[0226] TSKgel G2000HXL

[0227] • Solvent for determination: Tetrahydrofuran

[0228] • Measurement temperature: 40℃

[0229] [Experimental Example 1] (Determination of Gel Fraction)

[0230] The adhesive sheets obtained in the examples, comparative examples, and reference examples were cut to a size of 80mm × 80mm. The adhesive layer was wrapped in a polyester mesh (mesh size 200), and its mass was weighed using a precision balance. The mass of the mesh alone was subtracted to calculate the mass of the adhesive itself. This mass is denoted as M1.

[0231] Then, at room temperature (23°C), the adhesive wrapped in the above-mentioned polyester mesh was immersed in ethyl acetate for 24 hours. The adhesive was then removed and air-dried for 24 hours at 23°C and 50% relative humidity, followed by further drying in an oven at 80°C for 12 hours. After drying, its mass was weighed using a precision balance, and the mass of the mesh alone was subtracted to calculate the mass of the adhesive itself. This mass is denoted as M2. The gel fraction (%) is expressed as (M2 / M1) × 100. Thus, the gel fraction of the adhesive (before UV irradiation) is derived. The results are shown in Table 2.

[0232] On the other hand, the adhesive layer of the adhesive sheets obtained in the Examples, Comparative Examples, and Reference Examples was irradiated with active energy rays (ultraviolet; UV) under the following conditions through a light-peeling release sheet to cure the adhesive layer and form a cured adhesive layer. Additionally, for the adhesive sheet of Example 7, a plastic sheet (manufactured by MITSUBISHI GAS CHEMICAL COMPANY, INC., product name) with a polymethyl methacrylate (PMMA) resin layer laminated on a polycarbonate (PC) resin sheet was used.

[0233] An "iupilon-sheet MR58U" (thickness: 0.7 mm, containing UV absorber) was stacked on a light-peel release sheet, and active energy rays were irradiated through the plastic sheet. The gel fraction (after UV irradiation) of the cured adhesive layer was derived in the same manner as described above. The results are shown in Table 2.

[0234] <Conditions of Irradiation by Active Energy Rays>

[0235] • Use a high-pressure mercury lamp

[0236] Illuminance 200mW / cm 2 Light intensity 2000 mJ / cm 2

[0237] The UV illuminance photometer used is the "UVPF-A1" manufactured by EYE GRAPHICS Co., Ltd.

[0238] [Experimental Example 2] (Determination of Total Transmittance)

[0239] The adhesive layer of the adhesive sheet obtained in the Examples, Comparative Examples, and Reference Examples was adhered to the glass and used as the sample for measurement. Based on the background measurement performed on the glass, the total transmittance (%) of the above-mentioned sample was measured using a haze meter (manufactured by NIPPONDENSHOKU INDUSTRIES Co., Ltd., product name "NDH-5000") according to JIS K7361-1:1997. The results are shown in Table 2.

[0240] [Experimental Example 3] (Determination of Haze Value)

[0241] For the adhesive layers of the adhesive sheets obtained in the Examples, Comparative Examples, and Reference Examples, the haze value (%) was measured using a haze meter (manufactured by NIPPON DENSHOKU INDUSTRIES Co., Ltd., product name "NDH-5000") according to JIS K7136:2000. The results are shown in Table 2.

[0242] [Experimental Example 4] (Determination of L*a*b*)

[0243] For the adhesive layers of the adhesive sheets obtained in the Examples, Comparative Examples, and Reference Examples, the lightness L*, chromaticity a*, and chromaticity b* as specified by the CIE 1976 L*a*b* color system were measured using a simultaneous spectrophotometer (manufactured by NIPPONDENSHOKU INDUSTRIES Co., Ltd., product name "SQ2000"). The results are shown in Table 2.

[0244] [Experimental Example 5] (Determination of Adhesion)

[0245] The light-release release sheet was peeled off from the adhesive sheets obtained in the Examples, Comparative Examples, and Reference Examples. The exposed adhesive layer was then bonded to the easy-adhesive layer of a polyethylene terephthalate (PET) film (manufactured by TOYOBO Co., Ltd., product name "PETA4300", thickness: 100 μm) with an easy-adhesive layer, resulting in a laminate of a heavy-release release sheet / adhesive layer / PET film. The resulting laminate was cut into pieces 25 mm wide and 100 mm long and used as a sample.

[0246] Under conditions of 23°C and 50% RH, the re-peeling release sheet was peeled off from the above sample, and the exposed adhesive layer was attached to soda-lime glass (manufactured by Nippon Sheet Glass Co., Ltd.). Then, using a pressurizer manufactured by Kurihara Seisakusho Co., Ltd., it was pressurized at 0.5 MPa and 50°C for 20 minutes. Then, it was placed under conditions of 23°C and 50% RH for 24 hours.

[0247] Next, the adhesive layer was irradiated with active energy rays under the same conditions as in Test Example 1, through the aforementioned heavy-peel release sheet, to cure the adhesive layer and form a cured adhesive layer. Additionally, for the adhesive sheet of Example 7, a plastic sheet (manufactured by MITSUBISHI GAS CHEMICAL COMPANY, INC., product name "iupilon-sheet MR58U", thickness: 0.7 mm, containing UV absorber) with a PMMA layer laminated on a PC board was placed on the heavy-peel release sheet, and active energy rays were irradiated through the plastic sheet. Furthermore, Reference Example 1 was set to a state where active energy rays were not irradiated. Then, the adhesion (N / 25 mm) was measured using a tensile testing machine (manufactured by ORIENTEC CORPORATION, product name "TENSILON") under conditions of a peel speed of 300 mm / min and a peel angle of 180 degrees. Conditions not described here were measured according to JIS Z0237:2009. The results are shown in Table 2.

[0248] [Experimental Example 6] (Evaluation of Appearance Harmony)

[0249] The adhesive sheets obtained in the Examples, Comparative Examples, and Reference Examples were cut to 70mm x 70mm length and were bonded to the adhesive layer by being sandwiched between two soda-lime glass plates (manufactured by Nippon Sheet Glass Co., Ltd., 70mm x 70mm x 1.1mm thickness). Next, with one soda-lime glass plate in between, the adhesive layer was irradiated with active energy rays under the same conditions as in Test Example 1 to cure it, thus creating a cured adhesive layer, which was used as a sample. Reference Example 1 was set to a state where it was not irradiated with active energy rays.

[0250] The obtained samples were placed on black-printed paper (L*: 29.8, a*: -0.7, b*: 0.6) as a background. Then, under a three-wavelength fluorescent lamp (distance from the lamp: 200cm), the sample's integration with the background (its overall appearance) was visually assessed, and its appearance harmony was evaluated according to the following criteria. The results are shown in Table 2.

[0251] ◎: The sample blends very well with the background.

[0252] ○: The sample blends into the background to a certain extent.

[0253] ×: The sample and the background are clearly not blended together.

[0254] In addition, the color of the black-printed paper was determined using a spectrophotometer (manufactured by BYK, product name "spectro-guide") (as specified by the CIE 1976 L*a*b* color system).

[0255] [Experimental Example 7] (Evaluation of Text Visibility)

[0256] On a 15.6-inch monitor with a resolution of 1366×768 (manufactured by Fujitsu Limited, product name "LITEBOOKA574 / H"), white background black text (font: MS PGothic) is displayed at 100% resolution at a size of 5 to 20 points (in increments of 1 point).

[0257] The sample, prepared in the same manner as in Test Example 6, was placed on the aforementioned display. Then, at a distance of 50 cm from the display, the size of the legible text was visually confirmed, and the text visibility was evaluated according to the following criteria. The results are shown in Table 2.

[0258] ◎: Capable of recognizing 8-point text.

[0259] ○: Unable to fully recognize 8-pound text, but able to recognize 15-pound text.

[0260] ×: Unable to recognize 15-pound text.

[0261] [Experimental Example 8] (Evaluation of Segment Followership)

[0262] On the surface of a glass plate (manufactured by NSG Precision Cells, Inc., product name "corning glass eagle XG", 90mm x 50mm x 0.5mm thick), a frame shape (90mm x 50mm x 5mm wide, manufactured by Teikoku Printing InksMfg.Co., Ltd., product name "POS-911 ink") was screen-printed. Then, it was irradiated with ultraviolet light (80W / cm²). 2 Two metal halide lamps (15cm high, belt speed 10-15m / min) are used to cure the printed UV-curable ink, producing a stepped glass plate with printing-based step heights (5μm, 10μm).

[0263] The light-release peeler was peeled off from the adhesive sheets obtained in the Examples, Comparative Examples, and Reference Examples, and the exposed adhesive layer was adhered to the easy-adhesive layer of a polyethylene terephthalate (PET) film (manufactured by TOYOBO Co., Ltd., product name "PETA4300", thickness: 100 μm) having an easy-adhesive layer. Then, the heavy-release peeler was peeled off to expose the adhesive layer. Then, the above-described laminate was laminated onto each stepped glass plate using a laminator (manufactured by FUJIPLA Inc., product name "LPD3214") such that the adhesive layer covered the entire frame-shaped printed surface. Then, it was subjected to a heat treatment at 50°C and 0.5 MPa for 20 minutes, and then placed at atmospheric pressure, 23°C, and 50% RH for 24 hours.

[0264] Next, the adhesive layer was cured by irradiating it with active energy rays under the same conditions as in Example 1, through the PET film, to produce a cured adhesive layer. For the adhesive sheet of Example 7, a plastic sheet (manufactured by MITSUBISHI GAS CHEMICAL COMPANY, INC., product name "iupilon-sheet MR58U", thickness: 0.7 mm, containing UV absorber) with a PMMA layer laminated on a PC board was placed on the PET film, and irradiated with active energy rays through the plastic sheet. Then, it was stored under humid heat conditions of 85°C and 85% RH for 72 hours. Then, the step followability was evaluated according to the following criteria. Good step followability was defined as the printed steps being completely embedded in the cured adhesive layer; failure to follow the printed steps was defined as the steps being unable to follow the printed steps if floating or peeling was observed at the interface between the printed steps and the cured adhesive layer. In addition, the step followability was evaluated in the same manner as in Example 1, except without irradiation with active energy rays. The results are shown in Table 2.

[0265] ◎: Printing step difference is 10μm, which is good.

[0266] ○: Printing step difference is 5μm, which is good.

[0267] ×: Printing step difference is 5μm, with floating peel.

[0268] [Experimental Example 9] (Evaluation of Anti-foaming Properties)

[0269] The light-peeling release sheet is peeled off from the adhesive sheet obtained in the examples, comparative examples and reference examples, and the exposed adhesive layer is attached to the side of the PC board on which a PMMA layer is laminated, which is a plastic sheet (manufactured by MITSUBISHI GAS CHEMICAL COMPANY, INC., product name "iupilon-sheet MR58U", thickness: 0.7 mm, containing UV absorber), to obtain a plastic sheet with an adhesive layer.

[0270] The re-peeling release sheet is peeled off from the plastic sheet with the adhesive layer obtained above. Through the exposed adhesive layer, the plastic sheet is attached to a 70mm × 150mm soda-lime glass plate (manufactured by Nippon Sheet Glass Co., Ltd., thickness: 0.7mm). Then, it is subjected to pressure heat treatment at 50°C and 0.5MPa for 20 minutes, and placed at normal pressure, 23°C, and 50%RH for 24 hours.

[0271] Then, the adhesive layer was irradiated with active energy rays through a soda-lime glass plate under the same conditions as in Example 1, causing the adhesive layer to cure and forming a cured adhesive layer. In Example 7, active energy rays were irradiated only through a plastic plate, not through a soda-lime glass plate. Thus, a structure (70mm × 150mm) was obtained by bonding a plastic plate and a glass plate together with the cured adhesive layer.

[0272] For the above-mentioned structure, it was stored at high temperature and high humidity of 85°C and 85%RH for 72 hours. Then, the state of the interface between the cured adhesive layer and the adherend (plastic sheet, glass sheet) was visually inspected, and the anti-foaming property was evaluated according to the following criteria. In addition, except that no active energy rays were irradiated, the anti-foaming property was evaluated in the same manner as described above, referring to Example 1. The results are shown in Table 2.

[0273] ◎: No bubbles, no floating, no peeling.

[0274] ○: No floating or peeling occurred; a few bubbles were produced, but to a harmless degree. △: No floating or peeling occurred, but more bubbles were produced. ×: Floating and peeling occurred.

[0275]

[0276] [Table 2]

[0277]

[0278] As shown in Table 2, the display body using the adhesive sheet obtained in the examples has excellent appearance coordination and text visibility, as well as excellent step tracking and anti-bubbling properties.

[0279] Industrial applicability

[0280] The adhesive sheet of the present invention can be used, for example, for bonding between display components in a display body having a black frame, and is particularly suitable for bonding a protective panel with a step to the desired display component.

Claims

1. An adhesive sheet comprising a colored adhesive layer for bonding one display component to another display component, characterized in that, The adhesive layer is composed of an active energy-curable adhesive containing colorants. The total light transmittance of the adhesive layer is 3% or more. The haze value of the adhesive layer is below 80%. The lightness L* of the adhesive layer, as specified by the CIE 1976 L*a*b* color system, is 91 or less. When the thickness of the adhesive layer is set to Z μm, the content of the colorant in the adhesive, X by mass %, is a value that satisfies the following formula (I). 8≤X×Z<150···(I), wherein The colorant is a black pigment or dye.

2. An adhesive sheet comprising a colored adhesive layer for bonding one display body component to another display body component, characterized in that, The adhesive layer is composed of an active energy-curable adhesive containing colorants. The total light transmittance of the adhesive layer is 3% or more. The haze value of the adhesive layer is below 80%. The lightness L* of the adhesive layer, as specified by the CIE 1976 L*a*b* color system, is below 95. When the thickness of the adhesive layer is set to Z μm, the content of the colorant in the adhesive, X by mass %, is a value that satisfies the following formula (I). 8.8≤X×Z<150···(I), wherein The colorant is a black pigment or dye.

3. The adhesive sheet according to claim 1 or 2, characterized in that, The content of the colorant in the adhesive is more than 0.01% by mass and less than 2.0% by mass.

4. The adhesive sheet according to claim 1 or 2, characterized in that, The adhesive contains a photopolymerization initiator.

5. The adhesive sheet according to claim 1 or 2, wherein The adhesive contains a photopolymerization initiator, and the mass ratio of the amount of the photopolymerization initiator to the amount of the colorant is 0.5 to 20.

6. The adhesive sheet according to claim 4, wherein The photopolymerization initiator is a phosphine oxide.

7. The adhesive sheet according to claim 1 or 2, characterized in that, After the adhesive layer is bonded to soda-lime glass and irradiated with active energy rays, the adhesion force of the adhesive layer to the soda-lime glass is between 10N / 25mm and 100N / 25mm.

8. The adhesive sheet according to claim 1 or 2, characterized in that, It possesses: Two peeling plates; and The adhesive layer is held between the release tabs in a manner that makes contact with the release surfaces of the two release tabs.

9. A display body comprising a display body component, another display body component, and a cured adhesive layer for bonding the one display body component and the other display body component together, characterized in that, The cured adhesive layer is a cured adhesive layer formed by curing the adhesive layer of the adhesive sheet according to claim 1 or 2 with active energy rays.

10. The display body according to claim 9, characterized in that, At least one of the one display body component and the other display body component has a step at least on the side of the surface that is adhered to by the cured adhesive layer.

11. The display body according to claim 9, characterized in that, At least one of the display body components and the other display body component contains an ultraviolet absorber.

12. The display body according to claim 9, characterized in that, It has a black frame.

13. A method for manufacturing a display body, characterized in that, A laminate is fabricated in which one display body component is bonded to another display body component via an adhesive layer of the adhesive sheet as described in claim 1 or 2. The adhesive layer of the laminate is irradiated with active energy rays to cure the adhesive layer, thus forming a cured adhesive layer.

14. A method for manufacturing a display body, characterized in that, A laminate is fabricated by bonding one display body component to another display body component via an adhesive layer of the adhesive sheet as described in claim 6. The adhesive layer of the laminate is irradiated with ultraviolet light through a display body component containing an ultraviolet absorber, causing the adhesive layer to cure and forming a cured adhesive layer.

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