CN111748289A

CN111748289A - Colored adhesive sheet and display

Info

Publication number: CN111748289A
Application number: CN201911301433.XA
Authority: CN
Inventors: 小鲭翔; 高桥洋一; 荒井隆行
Original assignee: Lintec Corp
Current assignee: Lintec Corp
Priority date: 2019-03-29
Filing date: 2019-12-17
Publication date: 2020-10-09
Also published as: JP6792662B2; TW202035618A; KR20200115066A; JP2020164702A; TWI834763B

Abstract

The invention provides a colored adhesive sheet capable of improving the design of a display body and the display body with improved design. The colored adhesive sheet (1) is provided with a colored adhesive layer (11) containing a colorant for bonding one display body constituent member and another display body constituent member, and the average haze of the average value of the haze value at a wavelength of 780nm and the haze value at a wavelength of 380nm of the colored adhesive layer (11) is 1% to 60%.

Description

Colored adhesive sheet and display

Technical Field

The present invention relates to a colored adhesive sheet for adhering constituent members of a display, and a display using the colored adhesive sheet.

Background

Liquid crystal display devices have been increasingly used in recent years as displays (monitors), for example, displays for on-board use in instrument panels of automobiles, various instruments of car navigation systems and consoles, displays for tablet terminals used by general users, displays for commercial tablet terminals, digital signage and the like, displays for outdoor digital signage and the like.

As described above, in some cases, in a display body represented by a vehicle-mounted display, when the display body is turned off, the display body is required to exhibit a sense of unity with surrounding members of the display body, for example, a frame member, and to improve design. For this reason, it is conceivable to color the display, and for example, patent documents 1 to 4 disclose an invention relating to the coloring of the display.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 2000-313871

Patent document 2: japanese laid-open patent publication No. 2009-188298

Patent document 3: japanese patent laid-open No. 2012 and 234028

Patent document 4: japanese patent laid-open publication No. 2017-57375

Disclosure of Invention

Technical problem to be solved by the invention

However, the techniques disclosed in patent documents 1 to 4 are different in the purpose of coloring, and therefore, cannot provide a sense of unity between the display body and the surrounding member, thereby improving the design.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a colored adhesive sheet capable of improving the design of a display, and a display having improved design.

Means for solving the problems

In order to achieve the above object, the present invention provides a colored adhesive sheet comprising a colored adhesive layer composed of an adhesive containing a colorant for bonding one display constituent member and another display constituent member, wherein the colored adhesive layer has an average haze value of 1% or more and 60% or less, which is an average value of a haze value at a wavelength of 780nm and a haze value at a wavelength of 380nm (invention 1).

According to the above invention (invention 1), when the colored adhesive layer satisfying the above physical properties is applied to a display, the design of the display when the display is turned off, particularly the appearance harmony can be improved. For example, the display body can be given a sense of unity with surrounding members (in particular, a black frame member or the like).

In the above invention (invention 1), the difference between the haze value at a wavelength of 780nm and the haze value at a wavelength of 380nm in the colored adhesive layer is preferably 15% or less (invention 2).

In the above inventions (inventions 1 and 2), it is preferable that the standard deviation of the haze value in the wavelength region of the colored adhesive layer at each wavelength of a 5nm pitch of 380nm to 780nm is 5 or less (invention 3).

In the above invention (inventions 1 to 3), it is preferable that: the colored adhesive layer has a total light transmittance of 10% or more and less than 95%, and the colored adhesive layer has a chromaticity a and a chromaticity b defined by the CIE1976L a b color system of-7 to 7 (invention 4).

In the above-mentioned inventions (inventions 1 to 4), it is preferable that the average haze value, which is an average value of the haze value at a wavelength of 780nm and the haze value at a wavelength of 380nm, of a solution obtained by diluting the colorant with ethyl acetate by 1 ten thousand times is 1% or more and 60% or less (invention 5).

In the above inventions (inventions 1 to 5), it is preferable that a difference between a haze value at a wavelength of 780nm and a haze value at a wavelength of 380nm in a solution obtained by diluting the colorant with ethyl acetate by 1 ten thousand times is 30 percentage points or less (invention 6).

In the above inventions (inventions 1 to 6), it is preferable that the colorant is a black pigment (invention 7).

In the above inventions (inventions 1 to 7), the adhesive is preferably an acrylic adhesive (invention 8).

In the above inventions (inventions 1 to 8), the adhesive is preferably obtained by crosslinking an adhesive composition containing a (meth) acrylate polymer (a), a crosslinking agent (B) and a colorant (C) (invention 9).

In the above invention (inventions 1 to 9), the colored adhesive sheet preferably includes: two release sheets, and the colored adhesive layer sandwiched between the release sheets so as to be in contact with release surfaces of the two release sheets (invention 10).

A second aspect of the present invention provides a display device including: one display body constituting member, another display body constituting member, and a colored adhesive layer for bonding the one display body constituting member and the another display body constituting member to each other, wherein the colored adhesive layer is a colored adhesive layer (invention 11) of the colored adhesive sheet (inventions 1 to 10).

In the above invention (invention 11), it is preferable that at least one of the one display element constituting member and the other display element constituting member has a step on at least a surface of the side to be bonded with the colored adhesive layer (invention 12).

In the above inventions (inventions 11 and 12), the frame member preferably has a black color (invention 13).

Effects of the invention

According to the colored adhesive sheet of the present invention, the design of the display can be improved. In addition, the design of the display body of the present invention is improved.

Drawings

FIG. 1 is a sectional view of a colored adhesive sheet according to an embodiment of the present invention.

Fig. 2 is a cross-sectional view of a display body according to an embodiment of the present invention.

Fig. 3 is a plan view of a display body having a frame member according to an embodiment of the present invention.

Description of the reference numerals

1: a colored adhesive sheet; 11: a colored adhesive layer; 12a, 12 b: a release sheet; 2: a display body; 21: a first display body constituting member; 22: a second display body constituting member; 3: printing layer; 4: a frame material.

Detailed Description

Hereinafter, embodiments of the present invention will be described.

[ colored adhesive sheet ]

The colored adhesive sheet according to one embodiment of the present invention is prepared by laminating a release sheet on one surface or both surfaces of a colored adhesive layer composed of an adhesive containing a colorant for bonding one display constituent member and another display constituent member. The display body and the display body constituting member will be described later.

Fig. 1 shows a specific configuration of an example of the colored adhesive sheet of the present embodiment.

As shown in fig. 1, the colored adhesive sheet 1 is composed of two

release sheets

12a and 12b and a colored adhesive layer 11, and the colored adhesive layer 11 is sandwiched between the two

release sheets

12a and 12b so as to be in contact with the release surfaces of the two

release sheets

12a and 12 b. The release surface of the release sheet in the present specification means a surface having releasability in the release sheet, and includes any one of a surface subjected to a release treatment and a surface showing releasability even if the release treatment is not performed.

1. Each component

1-1. colored adhesive layer

The colored adhesive layer 11 of the colored adhesive sheet 1 of the present embodiment has an average haze value, which is an average value of a haze value at a wavelength of 780nm and a haze value at a wavelength of 380nm, of 1% to 60%. The haze value in the present specification is a value measured in accordance with JIS K7136: 2000.

When the colored adhesive layer 11 satisfying the above physical properties is applied to a display, the design of the display can be improved when the display is turned off. As an example of such design, appearance compatibility when the lamp is turned off can be cited. In this case, the display body can be given a sense of unity with surrounding members, for example, with a black frame material, thereby expressing a sense of high quality. Specifically, when the average haze is 1% or more, light incident on the display screen is moderately scattered when the display is turned off, and it is possible to make it difficult to distinguish the boundary between the display and the surrounding member (seamless). This improves the sense of unity between the display body and the surrounding members when the display body is turned off. On the other hand, when the average haze is 60% or less, the white-out of the display screen is suppressed when the display is turned off, and the feeling of integration with the surrounding members is improved. That is, when the display is turned off, the average haze is set to 1% or more and 60% or less, so that the display and the surrounding members can be given a sense of unity, and an excellent appearance can be exhibited. According to the colored adhesive sheet 1 of the present embodiment, the design of the display can be improved as described above.

Specific examples of the peripheral member include an automobile instrument panel having a lightness L of 23.2, a chroma a of-0.5, and a chroma b of-1.5, which are defined by the CIE1976L a b color system. The color tone of the surrounding member is preferably lightness L of 5 to 90, chroma a of-40 to 40, and chroma b of-40 to 40, more preferably lightness L of 10 to 80, chroma a of-30 to 30, chroma b of-30 to 30, still more preferably lightness L of 15 to 70, chroma a of-20 to 20, and chroma b of-20 to 20. The colored adhesive sheet 1 of the present embodiment can be suitably used for a display having a surrounding member with the above color tone.

The average haze is required to be 1% or more, preferably 1.5% or more, particularly preferably 1.8% or more, and more preferably 2.2% or more, from the viewpoint that the boundary between the display unit and its surrounding members is not easily recognized when the display unit is turned off. On the other hand, from the viewpoint of suppressing the white-out of the display screen when the display is turned off, the average haze needs to be 60% or less, preferably 45% or less, more preferably 30% or less, particularly preferably 20% or less, and further preferably 12% or less.

The difference (absolute value) between the haze value at a wavelength of 780nm and the haze value at a wavelength of 380nm in the colored adhesive layer 11 of the present embodiment is preferably 15% or less, particularly preferably 10% or less, and more preferably 7% or less. Thus, when the colored adhesive layer 11 of the present embodiment is applied to a display, the balance of color tones on the screen does not change regardless of the observation position or angle when the display is lit. As a result, when the display body is lit, the visibility (wide-angle visibility) of the image and video when viewed at a wide angle is improved, and a good image quality can be provided.

The lower limit of the difference in the haze value may be 0 percentage point, but is preferably 1 percentage point or more, more preferably 2 percentage points or more, particularly preferably 3 percentage points or more, and further preferably 4 percentage points or more, from the viewpoint of easily adjusting the average haze value to a desired value.

The colored adhesive layer 11 of the present embodiment has a haze value at a wavelength of 780nm of preferably 0.1 to 50%, more preferably 0.5 to 30%, particularly preferably 0.7 to 20%, and further preferably 1 to 10%, from the viewpoint of easily adjusting the average haze, the difference in haze values, and the standard deviation of the haze values described below to desired values.

In addition, from the viewpoint of easily adjusting the average haze value, the difference between the haze values, and the standard deviation of the haze values described later to desired values, the haze value at a wavelength of 380nm in the colored adhesive layer 11 of the present embodiment is preferably 0.1 to 60%, more preferably 1 to 40%, particularly preferably 2 to 30%, further preferably 4 to 20%, most preferably 5 to 15%,

The standard deviation of the haze value in the colored adhesive layer 11 of the present embodiment is preferably 5 or less, particularly preferably 3 or less, and further preferably 2 or less, at each wavelength of a 5nm pitch in a wavelength region of 380nm to 780nm (i.e., 380nm, 385nm, 390nm … … 775nm, 780 nm). Thus, when the colored adhesive layer 11 of the present embodiment is applied to a display, the balance of color tones on the screen does not change regardless of the observation position or angle when the display is lit. As a result, when the display body is lit, the visibility (wide-angle visibility) of the image and video when viewed at a wide angle is improved, and a good image quality can be provided.

The lower limit of the standard deviation is most preferably 0, and is usually preferably 0.1 or more, particularly preferably 0.4 or more, and further preferably 0.8 or more.

The total light ray haze value (the all-on-the-line ヘイズ value) of the colored adhesive layer 11 of the present embodiment is preferably 0.1 to 60%, more preferably 0.5 to 40%, particularly preferably 1 to 30%, further preferably 1.5 to 20%, and most preferably 2 to 15%, from the viewpoint of easily adjusting the average haze value, the difference in haze values, and the standard deviation to desired values.

The colored adhesive layer 11 of the present embodiment preferably has a total light transmittance (measured in accordance with JIS K7361-1: 1997) of 10% or more and less than 95%, and the color chromaticity a and the color chromaticity b of the colored adhesive layer 11, which are defined by the CIE1976L a b color system, are-7 to 7, respectively. The measurement methods of chromaticity a and chromaticity b in the present specification are shown in test examples described later.

When the colored adhesive layer 11 satisfies the above optical properties, when applied to a display, the blackness of the display increases when the display is turned off, and the design of the display (for example, appearance compatibility when the display is turned off) can be further improved. Specifically, the display body, particularly the display body for a vehicle, can be further improved in the sense of unity with the surrounding members, for example, with the black frame material. Further, by setting the total light transmittance to 10% or more, it is possible to ensure favorable visibility as a display (visibility of an image and a video depending on screen brightness).

From the viewpoint of easily adjusting the average haze, the difference between the haze values, and the standard deviation to desired values, the upper limit of the total light transmittance is preferably less than 95%, more preferably 90% or less, particularly preferably 85% or less, and further preferably 80% or less. From the viewpoint of visibility of the display, the lower limit value of the total light transmittance is preferably 25% or more, more preferably 40% or more, particularly preferably 50% or more, and further preferably 60% or more.

From the viewpoint of the design of the display, the chromaticity a is preferably-7 to 7, more preferably-5 to 5, particularly preferably-3 to 3, and further preferably-1 to 1. In addition, from the viewpoint of the design of the display, the chromaticity b is preferably-7 to 7, more preferably-5 to 5, particularly preferably-3 to 3, and further preferably-1 to 1.

On the other hand, the lightness L defined in the CIE1976L a b color system of the colored adhesive layer 11 is preferably 99 or less, more preferably 95 or less, particularly preferably 92 or less, and further preferably 91 or less, from the viewpoint that the average haze can be easily adjusted to 1% or more, and the boundary between the display body and the surrounding member is not easily distinguished. The lightness L is preferably 10 or more, more preferably 25 or more, particularly preferably 50 or more, further preferably 70 or more, and most preferably 80 or more, from the viewpoint that the average haze value can be easily adjusted to 60% or less to suppress the whitening of the screen, or the difference between the haze values and the standard deviation can be easily adjusted to a desired value.

The above optical properties can be achieved by appropriately selecting the type and content of the colorant contained in the adhesive constituting the colored adhesive layer 11.

The lower limit of the average haze, which is the average of the haze value at a wavelength of 780nm and the haze value at a wavelength of 380nm, of a solution obtained by diluting the colorant 1 ten thousand times with ethyl acetate is preferably 1% or more, particularly preferably 2% or more, and more preferably 3% or more. The upper limit value of the average haze of the colorant is preferably 60% or less, more preferably 40% or less, particularly preferably 30% or less, and further preferably 25% or less. By using such a colorant in an appropriate amount, the average haze of the colored adhesive layer 11 can be easily satisfied.

In addition, the difference between the haze value at a wavelength of 780nm and the haze value at a wavelength of 380nm in a solution obtained by diluting the colorant 1 ten thousand times with ethyl acetate is preferably 30% or less, more preferably 25% or less, particularly preferably 20% or less, and further preferably 16% or less. By using such a coloring agent in an appropriate amount, the difference in haze value of the colored adhesive layer 11 described above can be easily satisfied.

The lower limit of the difference in the haze values may be 0 percentage point, and is preferably 0.1 percentage point or more, particularly preferably 0.5 percentage point or more, and more preferably 1 percentage point or more, from the viewpoint that the average haze value of the colored adhesive layer 11 can be easily adjusted to 1% or more, or the difference in the haze values and the standard deviation of the colored adhesive layer 11 can be easily adjusted to desired values.

The haze value at a wavelength of 780nm of a solution obtained by diluting the colorant with ethyl acetate by 1 ten thousand times is preferably 0.1 to 50%, more preferably 0.5 to 40%, particularly preferably 1 to 30%, and further preferably 2 to 25%. The haze value at a wavelength of 380nm of a solution obtained by diluting the colorant with ethyl acetate by 1 ten thousand times is preferably 1 to 60%, more preferably 3 to 50%, particularly preferably 6 to 40%, and further preferably 10 to 30%. This makes it easy to satisfy the average haze, the difference between the haze values, and the standard deviation of the haze values described later.

Further, the standard deviation of the haze value at each wavelength of a 5nm pitch of a wavelength region from 380nm to 780nm (i.e., 380nm, 385nm, 390nm, … …, 775nm, 780nm) in a solution obtained by diluting the colorant with ethyl acetate by 1 ten thousand times is preferably 10 or less, more preferably 8 or less, particularly preferably 6 or less, and further preferably 5 or less. The lower limit of the standard deviation is most preferably 0, and is usually preferably 0.1 or more, particularly preferably 0.2 or more, and further preferably 0.3 or more. This makes it easy to satisfy the standard deviation of the haze value of the colored adhesive layer 11.

The colorant may be a pigment or a dye. The pigment may be an inorganic pigment or an organic pigment. From the viewpoint of durability of the obtained adhesive, an inorganic pigment is preferable. The color of the colorant is appropriately selected according to the color of the surrounding member to be provided with the sense of unity, and is preferably a dark color or a dark color such as black, brown, navy, violet, or blue, and particularly preferably black.

Examples of the inorganic pigments include 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, ATO (antimony tin oxide) pigments, and the like.

Examples of the organic pigments and organic dyes include amine (aminium) pigments, cyanine pigments, merocyanine pigments, croconium (croconium) pigments, squarylium (squarylium) pigments, azulene (azulene) pigments, polymethine pigments, naphthoquinone pigments, pyrylium pigments, phthalocyanine pigments, naphthalocyanine pigments, naphthalimide (naphthalimide) pigments, azo pigments, condensed azo pigments, indigoid pigments, perinone pigments, perylene pigments, dioxazine pigments, quinacridone pigments, isoindolinone pigments, quinolinone pigments, pyrrole pigments, thioindigoid pigments, metal complex pigments (metal complex salt dyes), dithiol metal complex pigments, indophenol pigments, triarylmethane pigments, anthraquinone pigments, dioxazine pigments, perylene pigments, and the like, Naphthol pigments, azomethine pigments, benzimidazolone pigments, pyranthrone pigments, threne pigments, and the like.

Examples of the black pigment include carbon black, copper oxide, ferroferric oxide, manganese dioxide, aniline black, and activated carbon. Examples of the black dye include a high-concentration plant dye and an azo dye.

The above-mentioned pigment or dye can be appropriately mixed and used in the colored adhesive layer 11 in order to obtain the target physical properties.

Among the above colorants, carbon black, nigrosine-based black dyes and chromate-based black dyes are preferable from the viewpoint of easily satisfying the above physical properties and easily expressing a sense of unity with surrounding members. The surface of the carbon black may be subjected to a predetermined treatment (e.g., a solvating treatment) or may not be subjected to the treatment.

The type of adhesive constituting the colored adhesive layer 11 of the colored adhesive sheet 1 of the present embodiment is not particularly limited, and may be any of, for example, an acrylic adhesive, a polyester adhesive, a polyurethane adhesive, a rubber adhesive, a silicone adhesive, and the like. The adhesive may be any of emulsion type, solvent type, and non-solvent type, and may be any of crosslinking type and non-crosslinking type. Among them, acrylic adhesives having excellent adhesive properties, optical characteristics, and the like are preferable.

The acrylic pressure-sensitive adhesive may be curable with active energy rays or may be curable with inactive energy rays. Further, as the acrylic pressure-sensitive adhesive, a crosslinking type acrylic pressure-sensitive adhesive is preferable, and a thermal crosslinking type acrylic pressure-sensitive adhesive is more preferable.

Specifically, the adhesive is preferably obtained by crosslinking an adhesive composition containing a (meth) acrylate polymer (a), a crosslinking agent (B), and a colorant (C) (hereinafter sometimes referred to as "adhesive composition P"). When the adhesive is an active energy ray-curable adhesive, the adhesive composition P preferably further contains an active energy ray-curable component (D).

The colorant (C) contained in the adhesive composition P is the above colorant. The adhesive obtained from the adhesive composition P can exhibit excellent optical characteristics, adhesive force, durability (step following property under high temperature and high humidity conditions), and the like. In the present specification, the term (meth) acrylic acid means acrylic acid and methacrylic acid. Other similar terms are also the same. Further, "polymer" also includes the concept of "copolymer".

(1) Components of adhesive compositions

(1-1) (meth) acrylate ester Polymer (A)

The (meth) acrylate polymer (a) of the present embodiment preferably contains a reactive group-containing monomer having a reactive group reactive with the crosslinking agent (B) in the molecule as a monomer unit constituting the polymer. By reacting the reactive group derived from the reactive group-containing monomer with the crosslinking agent (B), a crosslinked structure (three-dimensional network structure) can be formed, and an adhesive having a desired cohesive force can be obtained.

Examples of the reactive group-containing monomer include a monomer having a hydroxyl group in the molecule (hydroxyl group-containing monomer), a monomer having a carboxyl group in the molecule (carboxyl group-containing monomer), and a monomer having an amino group in the molecule (amino group-containing monomer). Among these, a hydroxyl group-containing monomer or a carboxyl group-containing monomer having excellent reactivity with the crosslinking agent (B) is preferable, and a hydroxyl group-containing monomer and a carboxyl group-containing monomer are also preferably used together.

Examples of the hydroxyl group-containing monomer include hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate. Among them, hydroxyalkyl (meth) acrylates having a hydroxyalkyl group having 1 to 4 carbon atoms are preferable from the viewpoint of reactivity of the hydroxyl group in the obtained (meth) acrylate polymer (a) with the crosslinking agent (B) and copolymerizability with other monomers. Specifically, for example, 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate and the like are preferably mentioned, and 2-hydroxyethyl acrylate or 4-hydroxybutyl acrylate is particularly preferably mentioned. These hydroxyl group-containing monomers may be used alone or in combination of two or more.

Examples of the carboxyl group-containing monomer include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. Among these, acrylic acid is preferable because of reactivity of the carboxyl group in the obtained (meth) acrylate polymer (a) with the crosslinking agent (B) and copolymerizability with other monomers. These carboxyl group-containing monomers may be used alone or in combination of two or more.

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

The (meth) acrylate polymer (a) preferably contains the reactive group-containing monomer as a monomer unit constituting the polymer at a lower limit of 1% by mass or more, more preferably 5% by mass or more, and particularly preferably 10% by mass or more. Further, since the dispersibility of the colorant (C) in the adhesive tends to be more favorable, the content of the colorant (C) is more preferably 12% by mass or more, and most preferably 15% by mass or more. On the other hand, the (meth) acrylate polymer (a) preferably contains a reactive group-containing monomer as a monomer unit constituting the polymer, the upper limit of which is 35% by mass or less, more preferably 30% by mass or less, and particularly preferably 20% by mass or less. Further, the colorant (C) in the adhesive tends to be more excellent in dispersibility, and therefore, the content of 18 mass% or less is more preferable. When the (meth) acrylate polymer (a) contains the reactive group-containing monomer as a monomer unit in the above-mentioned amount, a favorable crosslinked structure can be formed in the obtained adhesive, and a desired cohesive force can be obtained. Further, since the dispersibility of the colorant (C) in the adhesive tends to be good, the obtained adhesive has good reproducibility and uniformity of the optical properties, and exhibits excellent design properties and visibility. Further, when the reactive group-containing monomer is a hydroxyl group-containing monomer, the content is particularly preferably 15% by mass or more. In this case, a predetermined amount of hydroxyl groups remain in the adhesive. When a hydroxyl group is a hydrophilic group and such a hydrophilic group is present in a predetermined amount in the adhesive, the adhesive has good compatibility with moisture that has entered the adhesive under high-temperature and high-humidity conditions even when the adhesive is left under high-temperature and high-humidity conditions, and as a result, whitening of the adhesive when the adhesive is returned to normal temperature and normal humidity is suppressed (excellent resistance to moist-heat whitening).

Further, the (meth) acrylate polymer (a) preferably does not contain a carboxyl group-containing monomer as a monomer unit constituting the polymer. Since the carboxyl group is an acid component, the carboxyl group-containing monomer is not contained, and therefore, even when a substance which causes a problem due to an acid, for example, a transparent conductive film such as tin-doped indium oxide (ITO), a metal film, or the like is present on an object to which the adhesive is to be attached, the problem (corrosion, change in resistance value, or the like) due to the acid can be suppressed. However, it is also permissible to contain a predetermined amount of the carboxyl group-containing monomer to such an extent that the above-described problems do not occur. Specifically, the carboxyl group-containing monomer is allowed to be contained as a monomer unit in the (meth) acrylate polymer (a) in an amount of 0.1% by mass or less, preferably 0.01% by mass or less, and more preferably 0.001% by mass or less.

The (meth) acrylate polymer (a) preferably contains an alkyl (meth) acrylate as a monomer unit constituting the polymer. This can exhibit good adhesion. The alkyl group may be linear or branched.

The alkyl (meth) acrylate is preferably an alkyl (meth) acrylate having an alkyl group with 1 to 20 carbon atoms from the viewpoint of adhesiveness and dispersibility of the colorant (C). Examples of the alkyl (meth) acrylate having an alkyl group with 1 to 20 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, n-decyl (meth) acrylate, n-dodecyl (meth) acrylate, tetradecyl (meth) acrylate, hexadecyl (meth) acrylate, and octadecyl (meth) acrylate. Among these, from the viewpoint of further improving the adhesion, a (meth) acrylate having an alkyl group with 1 to 8 carbon atoms is preferable, methyl (meth) acrylate, n-butyl (meth) acrylate, or 2-ethylhexyl (meth) acrylate is particularly preferable, and methyl methacrylate, n-butyl acrylate, or 2-ethylhexyl acrylate is further preferable. These alkyl (meth) acrylates may be used alone or in combination of two or more.

The (meth) acrylate polymer (a) preferably contains 50% by mass or more, particularly preferably 60% by mass or more, and further preferably 65% by mass or more of an alkyl (meth) acrylate as a monomer unit constituting the polymer. When the lower limit of the content of the alkyl (meth) acrylate is as described above, the (meth) acrylate polymer (a) can exhibit appropriate tackiness. Further, the dispersibility of the colorant (C) in the adhesive tends to be good, and the desired adhesiveness of the (meth) acrylate polymer (a) is not impaired. The obtained adhesive can exhibit appropriate adhesiveness, and also has good reproducibility and uniformity of the optical properties, and excellent design properties and visibility. On the other hand, the (meth) acrylic acid ester polymer (a) preferably contains 99% by mass or less, more preferably 95% by mass or less, particularly preferably 90% by mass or less, and further preferably 85% by mass or less of an alkyl (meth) acrylate as a monomer unit constituting the polymer. When the upper limit of the content of the alkyl (meth) acrylate is as described above, other monomer components such as a reactive functional group-containing monomer can be introduced into the (meth) acrylate polymer (a) in an appropriate amount.

The (meth) acrylate polymer (a) preferably contains a monomer having an alicyclic structure in the molecule (alicyclic structure-containing monomer) as a monomer unit constituting the polymer. Since the alicyclic structure-containing monomer has a large volume, it is presumed that the presence thereof in the polymer enlarges the interval between the polymers, and the resulting adhesive can have excellent flexibility. This provides excellent step following properties of the adhesive.

The alicyclic carbon ring in the alicyclic structure-containing monomer may be a saturated structure or may have an unsaturated bond in a part thereof. The alicyclic structure may be a monocyclic alicyclic structure, or may be a polycyclic alicyclic structure such as a bicyclic structure or a tricyclic structure. The alicyclic structure is preferably a polycyclic alicyclic structure (polycyclic structure) from the viewpoint of making the distance between the obtained (meth) acrylate polymers (a) appropriate and imparting higher stress relaxation property to the adhesive. Further, the polycyclic structure is particularly preferably a bicyclic ring to tetracyclic ring in view of compatibility of the (meth) acrylate polymer (a) with other components. In addition, from the viewpoint of providing stress relaxation properties as described above, the number of carbon atoms of the alicyclic structure (the number of all carbon atoms of the portion indicating a ring, which means the total number of carbon atoms when a plurality of rings are present independently) is preferably 5 or more in general, and more preferably 7 or more in particular. On the other hand, the upper limit of the number of carbon atoms of the alicyclic structure is not particularly limited, but is preferably 15 or less, and particularly preferably 10 or less, from the viewpoint of compatibility as described above.

Specific examples of the alicyclic structure-containing monomer include cyclohexyl (meth) acrylate, dicyclopentanyl (meth) acrylate, adamantyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, etc., and among them, dicyclopentanyl (meth) acrylate (carbon number of alicyclic structure: 10), adamantyl (meth) acrylate (carbon number of alicyclic structure: 10), or isobornyl (meth) acrylate (carbon number of alicyclic structure: 7) which exhibits more excellent step following property is preferable, isobornyl (meth) acrylate is particularly preferable, and isobornyl acrylate is more preferable. These alicyclic structure-containing monomers may be used singly or in combination of two or more.

When the (meth) acrylate polymer (a) contains an alicyclic structure-containing monomer as a monomer unit constituting the polymer, the alicyclic structure-containing monomer is contained preferably in an amount of 1 mass% or more, particularly preferably 4 mass% or more, and further preferably 8 mass% or more. The (meth) acrylate polymer (a) preferably contains 30% by mass or less, particularly preferably 22% by mass or less, and further preferably 14% by mass or less of an alicyclic structure-containing monomer as a monomer unit constituting the polymer. When the content of the alicyclic structure-containing monomer is in the above range, the obtained adhesive is more excellent in step following property and also more excellent in adhesion to plastics.

Further, the (meth) acrylic acid ester polymer (a) preferably contains a nitrogen atom-containing monomer as a monomer unit constituting the polymer. By having a nitrogen atom monomer as a constituent unit in a polymer, a predetermined polarity can be imparted to an adhesive, and the adhesive is excellent in affinity even for an adherend having a certain polarity such as glass. From the viewpoint of imparting suitable rigidity to the (meth) acrylate polymer (a), the nitrogen atom-containing monomer is preferably a monomer having a nitrogen-containing heterocycle. In addition, from the viewpoint of enhancing the degree of freedom of the portion derived from the nitrogen atom-containing monomer in the high dimensional structure of the adhesive agent to be constituted, it is preferable that the nitrogen atom-containing monomer does not contain a reactive unsaturated double bond group other than one polymerizable group used in the polymerization for forming the (meth) acrylate polymer (a).

Examples of the monomer having a nitrogen-containing heterocycle include N- (meth) acryloylmorpholine, N-vinyl-2-pyrrolidone, N- (meth) acryloylpyrrolidone, N- (meth) acryloylpiperidine, N- (meth) acryloylpyrrolidine, N- (meth) acryloylaziridine, aziridinylethyl (meth) acrylate, 2-vinylpyridine, 4-vinylpyridine, 2-vinylpyrazine, 1-vinylimidazole, N-vinylcarbazole, N-vinylphthalimide, and the like, and among them, N- (meth) acryloylmorpholine which exhibits more excellent adhesive force is preferable, and N-acryloylmorpholine is particularly preferable. These monomers having a nitrogen-containing heterocycle may be used alone or in combination of two or more.

When the (meth) acrylate polymer (a) contains a nitrogen atom-containing monomer as a monomer unit constituting the polymer, the content of the nitrogen atom-containing monomer is preferably 1% by mass or more, particularly preferably 4% by mass or more, and more preferably 8% by mass or more. The (meth) acrylate polymer (a) preferably contains 20% by mass or less, particularly preferably 16% by mass or less, and further preferably 12% by mass or less of the nitrogen atom-containing monomer as a monomer unit constituting the polymer. When the content of the nitrogen atom-containing monomer is within the above range, the resulting adhesive can sufficiently exhibit excellent adhesion to glass.

The (meth) acrylate polymer (a) may contain other monomers as the monomer unit constituting the polymer, as required. In order not to inhibit the above-mentioned action of the reactive functional group-containing monomer, as the other monomer, a monomer not containing a reactive functional group is preferable. Examples of the monomer include alkoxyalkyl (meth) acrylates such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate, vinyl acetate, and styrene. These other monomers may be used alone or in combination of two or more.

The (meth) acrylate polymer (a) is preferably a linear polymer. Since the linear polymer is likely to cause entanglement of molecular chains and is expected to improve cohesive force, the adhesive obtained is likely to have appropriate storage modulus, gel fraction, adhesive force, and the like, and is excellent in step difference following properties under high-temperature and high-humidity conditions.

The (meth) acrylate polymer (a) is preferably a solution polymer obtained by a solution polymerization method. Since a high molecular weight polymer is easily obtained by using a solution polymer, and an improvement in cohesive force can be expected, the storage modulus, gel fraction, adhesive force, and the like of the obtained adhesive are easily appropriate, and the adhesive is excellent in step difference following properties under high temperature and high humidity conditions.

The polymerization form of the (meth) acrylate polymer (a) may be a random copolymer or a block copolymer.

The lower limit of the weight average molecular weight of the (meth) acrylate polymer (a) is preferably 20 ten thousand or more, particularly preferably 30 ten thousand or more, and more preferably 40 ten thousand or more, and from the viewpoint of dispersibility of the colorant (C), more preferably 50 ten thousand or more, and particularly preferably 70 ten thousand or more. When the lower limit of the weight average molecular weight of the (meth) acrylate polymer (a) is as described above, the storage modulus, gel fraction, adhesive force and the like of the obtained adhesive are easily appropriate, and the step difference following property under high temperature and high humidity conditions is further excellent. Further, since the colorant (C) tends to be dispersed well in the adhesive, the obtained adhesive has good reproducibility and uniformity of the optical properties, and exhibits excellent design properties and visibility.

The upper limit of the weight average molecular weight of the (meth) acrylate polymer (a) is preferably 200 ten thousand or less, particularly preferably 150 ten thousand or less, and more preferably 100 ten thousand or less. When the upper limit of the weight average molecular weight of the (meth) acrylate polymer (a) is set as described above, the storage modulus, gel fraction, adhesive force and the like of the obtained adhesive are easily appropriate, and the initial step following property is further excellent. The weight average molecular weight in the present specification is a value in terms of standard polystyrene measured by a Gel Permeation Chromatography (GPC) method.

In the adhesive composition P, one kind of the (meth) acrylate polymer (a) may be used alone, or two or more kinds may be used in combination.

(1-2) crosslinking agent (B)

The crosslinking agent (B) can crosslink the (meth) acrylate polymer (a) by heating the adhesive composition P, and can favorably form a three-dimensional network structure. This improves the cohesive force of the obtained adhesive, and the adhesive is excellent in step following properties under high-temperature and high-humidity conditions.

The crosslinking agent (B) may be a substance that reacts with the reactive group of the (meth) acrylate polymer (a), and examples thereof 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 the above, when the reactive group of the (meth) acrylate polymer (a) is a hydroxyl group, an isocyanate-based crosslinking agent excellent in reactivity with the hydroxyl group is preferably used, and when the reactive group of the (meth) acrylate polymer (a) is a carboxyl group, an epoxy-based crosslinking agent excellent in reactivity with the carboxyl group is preferably used. The crosslinking agent (B) may be used alone or in combination of two or more.

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

Examples of the epoxy-based crosslinking agent include 1, 3-bis (N, N-diglycidylaminomethyl) cyclohexane, N, N, N ', N' -tetraglycidyl-m-xylylenediamine, ethylene glycol diglycidyl ether, 1, 6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidylaniline, and diglycidylamine. Among them, 1, 3-bis (N, N-diglycidylaminomethyl) cyclohexane is preferable from the viewpoint of reactivity with a carboxyl group.

The content of the crosslinking agent (B) in the adhesive composition P is preferably 0.01 part by mass or more, particularly preferably 0.05 part by mass or more, and more preferably 0.1 part by mass or more, relative to 100 parts by mass of the (meth) acrylate polymer (a). The content is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, particularly preferably 1 part by mass or less, and further preferably 0.4 part by mass or less. When the content of the crosslinking agent (B) is in the above range, the obtained adhesive exhibits good cohesive force, easily satisfies the required storage modulus, gel fraction, adhesive force, and the like, and is further excellent in step difference following properties under high-temperature and high-humidity conditions.

(1-3) colorant (C)

The colorant (C) is the above colorant. The specific species are the same as described above.

The content of the colorant (C) is preferably 0.01 part by mass or more, more preferably 0.05 part by mass or more, particularly preferably 0.1 part by mass or more, and further preferably 0.2 part by mass or more, relative to 100 parts by mass of the (meth) acrylate polymer (a). The content is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, particularly preferably 2 parts by mass or less, and further preferably 1 part by mass or less. When the content of the colorant (C) is in the above range, the above optical properties can be easily satisfied.

(1-4) active energy ray-curable component (D)

It is presumed that in an adhesive obtained by curing an adhesive obtained by crosslinking the adhesive composition P with an active energy ray, the active energy ray-curable components (D) are polymerized with each other, and the polymerized active energy ray-curable components (D) are entangled with the crosslinked structure (three-dimensional network structure) of the (meth) acrylate polymer (a). The adhesive having a high-dimensional structure exhibits very excellent durability, and is particularly excellent in step following properties under high-temperature and high-humidity conditions.

The active energy ray-curable component (D) is not particularly limited as long as it is curable by irradiation with an active energy ray and can obtain the above-described effects, and may be any of a monomer, an oligomer, or a polymer, or a mixture of these. Among them, polyfunctional acrylate monomers having more excellent blister resistance can be preferably used.

Examples of the polyfunctional acrylate monomer include 1, 4-butanediol di (meth) acrylate, 1, 6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, neopentyl glycol adipate di (meth) acrylate, neopentyl glycol hydroxypivalate di (meth) acrylate, dicyclopentyl di (meth) acrylate, bifunctional types such as tricyclodecane dimethanol (meth) acrylate, caprolactone-modified dicyclopentenyl di (meth) acrylate, ethylene oxide-modified phosphoric acid di (meth) acrylate, di (acryloyloxyethyl) isocyanurate, allylated cyclohexyl di (meth) acrylate, ethoxylated bisphenol a diacrylate, and 9, 9-bis [4- (2-acryloyloxyethoxy) phenyl ] fluorene; trifunctional types 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, tris (acryloyloxyethyl) isocyanurate, and caprolactone-modified tris (2- (meth) acryloyloxyethyl) isocyanurate; tetrafunctional types such as diglycerin tetra (meth) acrylate and pentaerythritol tetra (meth) acrylate; pentafunctional types such as propionic acid-modified dipentaerythritol penta (meth) acrylate; and hexa-functional types such as dipentaerythritol hexa (meth) acrylate and caprolactone-modified dipentaerythritol hexa (meth) acrylate. These polyfunctional acrylate monomers may be used alone or in combination of two or more. Further, the molecular weight of the polyfunctional acrylate monomer is preferably less than 1000 from the viewpoint of compatibility with the (meth) acrylate polymer (a).

Among the above, from the viewpoint of the blister resistance of the adhesive to be obtained, polyfunctional acrylate monomers having an isocyanurate structure in the molecule, such as bis (acryloyloxyethyl) isocyanurate, tris (acryloyloxyethyl) isocyanurate, and caprolactone-modified tris (2- (meth) acryloyloxyethyl) isocyanurate, or polyfunctional acrylate monomers having a cyclic structure (particularly, a cycloalkane structure) in the molecule, such as tricyclodecane dimethanol (meth) acrylate, are preferable, polyfunctional acrylate monomers having at least three functionalities and an isocyanurate structure in the molecule, or polyfunctional acrylate monomers having at least two functionalities and a polycyclic structure (particularly, a cycloalkane polycyclic structure) in the molecule, and caprolactone-modified tris (2- (meth) acryloyloxyethyl) isocyanurate or tricyclodecane dimethanol (methyl) are particularly preferable The acrylate is more preferably caprolactone-modified tris (2-acryloyloxyethyl) isocyanurate or tricyclodecane dimethanol acrylate, and most preferably caprolactone-modified tris (2-acryloyloxyethyl) isocyanurate.

From the viewpoint of more excellent step following properties under high temperature and high humidity conditions of the adhesive after curing with active energy rays, the lower limit of the content of the active energy ray-curable component (D) in the adhesive composition P is preferably 1 part by mass or more, particularly preferably 3 parts by mass or more, and more preferably 4 parts by mass or more, per 100 parts by mass of the (meth) acrylate polymer (a). On the other hand, the upper limit of the content is preferably 20 parts by mass or less, particularly preferably 12 parts by mass or less, and further preferably 8 parts by mass or less, from the viewpoint of the adhesive force of the adhesive after curing with an active energy ray.

(1-5) photopolymerization initiator (E)

When ultraviolet rays are used as the active energy rays for curing the adhesive composition P, the adhesive composition P preferably further contains a photopolymerization initiator (E). By containing the photopolymerization initiator (E) in this manner, the active energy ray-curable component (D) can be efficiently polymerized, and the polymerization curing time and the irradiation dose of active energy rays can be reduced.

Examples of the photopolymerization initiator (E) include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2-dimethoxy-2-phenylacetophenone, 2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1- [4- (methylthio) phenyl ] -2-morpholinyl-1-one, 4- (2-hydroxyethoxy) phenyl-2- (hydroxy-2-propyl) ketone, benzophenone, p-phenylbenzophenone, and the like, 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, benzildimethylketal, acetophenone dimethylketal, p-dimethylaminobenzoate, oligo [ 2-hydroxy-2-methyl-1 [4- (1-methylvinyl) phenyl ] propanone ], 2,4, 6-trimethylbenzoyl-diphenyl-phosphine oxide, bis (2,4, 6-trimethylbenzoyl) -phenylphosphine oxide and the like. These photopolymerization initiators may be used alone or in combination of two or more.

Among the above, a phosphine oxide-based photopolymerization initiator is preferable, which is easily cracked and easily and surely cures an adhesive even when irradiated with ultraviolet rays through a plastic plate containing an ultraviolet absorber. Specifically, 2,4, 6-trimethylbenzoyl-diphenyl-phosphine oxide, bis (2,4, 6-trimethylbenzoyl) phenylphosphine oxide, and the like are preferable.

The lower limit of the content of the photopolymerization initiator (E) in the adhesive composition P is preferably 0.1 part by mass or more, particularly preferably 1 part by mass or more, and more preferably 5 parts by mass or more, per 100 parts by mass of the active energy ray-curable component (D). The upper limit is preferably 30 parts by mass or less, particularly preferably 20 parts by mass or less, and further preferably 12 parts by mass or less.

The mass ratio of the amount of the photopolymerization initiator (E) to the amount of the colorant (C) (photopolymerization initiator (E)/colorant (C)) is preferably 0.01 or more, particularly preferably 0.1 or more, and more preferably 0.2 or more. The mass ratio is preferably 5 or less, particularly preferably 3 or less, and further preferably 1 or less. When the ratio of the amount of the photopolymerization initiator (E) to the amount of the colorant (C) is in the above range, the above optical properties are easily satisfied, and an adhesive having an appropriate cohesive force or adhesive property is easily obtained by curing with an active energy ray, and the poor followability under high temperature and high humidity conditions is further excellent.

(1-6) various additives

Various additives generally used in acrylic adhesives, for example, silane coupling agents, rust inhibitors, ultraviolet absorbers, antistatic agents, tackifiers, antioxidants, light stabilizers, softeners, refractive index modifiers, and the like can be added to the adhesive composition P as needed. In addition, a polymerization solvent or a dilution solvent described later is not included in the additive constituting the adhesive composition P.

Among the above, the adhesive composition P preferably contains a silane coupling agent. Thus, the adhesive property to the adherend is improved regardless of whether the adherend is a plastic plate or a glass member, and the step following property under high-temperature and high-humidity conditions is further excellent.

The silane coupling agent is preferably an organosilicon compound having at least 1 alkoxysilyl group in the molecule, which has good compatibility with the (meth) acrylate polymer (a) and light transmittance.

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

The content of the silane coupling agent in the adhesive composition P is preferably 0.01 part by mass or more, particularly preferably 0.05 part by mass or more, and more preferably 0.1 part by mass or more, relative to 100 parts by mass of the (meth) acrylate polymer (a). The content is preferably 1 part by mass or less, particularly preferably 0.5 part by mass or less, and further preferably 0.3 part by mass or less.

(2) Preparation of adhesive composition

The adhesive composition P can be prepared by: the (meth) acrylate polymer (a) is prepared, and the obtained (meth) acrylate polymer (a), the crosslinking agent (B), and the colorant (C) are mixed, and if necessary, the active energy ray-curable component (D), the photopolymerization initiator (E), and additives are added.

The (meth) acrylate polymer (a) can be prepared by polymerizing a mixture of monomers constituting the polymer by a general radical polymerization method. The polymerization of the (meth) acrylate polymer (a) is preferably carried out by a solution polymerization method using a polymerization initiator as needed. However, the present invention is not limited thereto, and polymerization can be carried out without a solvent. Examples of the polymerization solvent include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, and methyl ethyl ketone, and two or more of them may be used simultaneously.

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

Examples of the organic peroxide include benzoyl peroxide, tert-butyl peroxybenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di (2-ethoxyethyl) peroxydicarbonate, tert-butyl peroxyneodecanoate, tert-butyl peroxypivalate, 3,5, 5-trimethylhexanoyl peroxide, dipropyl peroxide, and diacetyl peroxide.

In the polymerization step, a chain transfer agent such as 2-mercaptoethanol is added to adjust the weight average molecular weight of the obtained polymer.

After the (meth) acrylate polymer (a) is obtained, the crosslinking agent (B), the colorant (C), and if necessary, a diluting solvent, the active energy ray-curable component (D), the photopolymerization initiator (E), and additives are added to a solution of the (meth) acrylate polymer (a) and sufficiently mixed to obtain the adhesive composition P (coating solution) diluted with the solvent. In the case where a solid substance is used for any of the above-mentioned components, or in the case where a precipitate is formed when the solid substance is mixed with another component in an undiluted state, the component may be dissolved or diluted in a diluting solvent in advance and then mixed with another component.

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

The concentration and viscosity of the coating solution prepared in this manner are not particularly limited as long as they are within a range in which coating can be performed, and may be appropriately selected depending on the case. For example, the adhesive composition P is diluted so that the concentration thereof is 10 to 60 mass%. In addition, when obtaining the coating solution, it is not essential to add a diluting solvent or the like, and the diluting solvent may not be added as long as the adhesive composition P has a viscosity capable of being coated or the like. In this case, the adhesive composition P is a coating solution in which the polymerization solvent of the (meth) acrylate polymer (a) is directly used as a dilution solvent.

(3) Formation of colored adhesive layer

The colored adhesive layer 11 of the present embodiment is preferably composed of an adhesive that crosslinks (the coating layer of) the adhesive composition P. The crosslinking of the adhesive composition P can generally be carried out by heat treatment. Further, the drying treatment when evaporating the diluting solvent or the like from the coating layer of the adhesive composition P applied to the desired object may be used as the heating treatment.

The heating temperature of the heating treatment is preferably 50 to 150 ℃, and particularly preferably 70 to 120 ℃. The heating time is preferably 10 seconds to 10 minutes, and particularly preferably 50 seconds to 2 minutes.

After the heat treatment, a curing period of about 1 to 2 weeks may be set at normal temperature (e.g., 23 ℃ C., 50% RH) as necessary. When the curing period is required, the adhesive is formed after the curing period, and when the curing period is not required, the adhesive is formed directly after the heat treatment is completed.

By the above-mentioned heat treatment (and curing), the (meth) acrylate polymer (a) is sufficiently crosslinked via the crosslinking agent (B). The adhesive obtained in this way easily satisfies the required storage modulus, gel fraction, adhesive force, and the like, and is excellent in step following properties under high-temperature and high-humidity conditions.

(4) Physical Properties of adhesive

The adhesive of the present embodiment preferably has the following physical properties.

(4-1) gel fraction

The lower limit of the gel fraction in the present embodiment is preferably 20% or more, more preferably 40% or more, particularly preferably 50% or more, and further preferably 60% or more. When the lower limit of the gel fraction of the adhesive is as described above, the adhesive has a high cohesive force, and the step following property under high-temperature and high-humidity conditions is more excellent. The upper limit of the gel fraction of the pressure-sensitive adhesive of the present embodiment is preferably 100% or less, more preferably 90% or less, particularly preferably 80% or less, and further preferably 70% or less. When the upper limit of the gel fraction of the adhesive is as described above, the adhesive does not become too hard, and is excellent in both initial step following properties and step following properties under high-temperature and high-humidity conditions. Further, the adhesive composition exhibits good adhesive force and is more excellent in adhesion to an adherend.

Here, the method of measuring the gel fraction of the adhesive is shown in the test examples described later. When the adhesive is an active energy ray-curable adhesive, the gel fraction of the adhesive after curing with an active energy ray is defined. In addition, when the adhesive is an active energy ray-curable adhesive, the gel fraction of the adhesive before curing by an active energy ray is preferably 20 to 70%, particularly preferably 30 to 60%, and further preferably 40 to 55%, from the viewpoint of enabling good initial step following properties.

(4-2) storage modulus

The lower limit of the storage modulus at 23 ℃ of the adhesive of the present embodiment is preferably 0.001MPa or more, more preferably 0.01MPa or more, particularly preferably 0.05MPa or more, and still more preferably 0.1MPa or more. When the lower limit of the storage modulus is set to the above value, the step following property under high temperature and high humidity conditions is excellent. The upper limit of the storage modulus is preferably 2MPa or less, more preferably 1MPa or less, particularly preferably 0.8MPa or less, further preferably 0.4MPa or less, and most preferably 0.2MPa or less. When the upper limit value of the storage modulus is set to the above value, the initial step following property and the step following property under high temperature and high humidity conditions are excellent.

Here, the storage modulus in the present specification is a value measured by a twist cut method (ね was manufactured by りせ was manufactured by one turn) at a measurement frequency of 1Hz in accordance with JIS K7244-6. Specifically, the following test examples are shown. When the adhesive is an active energy ray-curable adhesive, the storage modulus of the adhesive after curing with an active energy ray is defined. In addition, when the adhesive is an active energy ray-curable adhesive, the storage modulus of the adhesive before curing by an active energy ray is preferably 0.01 to 1MPa, particularly preferably 0.02 to 0.5MPa, and more preferably 0.04 to 0.1MPa, from the viewpoint of enabling the initial step following property to be good.

(5) Thickness of colored adhesive layer

The lower limit of the thickness of the colored adhesive layer 11 is preferably 1 μm or more, more preferably 2 μm or more, and particularly preferably 4 μm or more. When the lower limit of the thickness of the colored adhesive layer 11 is as described above, the optical properties described above are easily satisfied and a desired adhesive force is easily exhibited in relation to the content of the colorant (C). From the viewpoint of ease of exhibiting excellent step following property, the lower limit of the thickness of the colored adhesive layer 11 is preferably 10 μm or more, more preferably 20 μm or more, particularly preferably 50 μm or more, and further preferably 80 μm or more.

On the other hand, the upper limit of the thickness of the colored adhesive layer 11 is preferably 500 μm or less, more preferably 300 μm or less, particularly preferably 200 μm or less, and further preferably 150 μm or less. If the upper limit of the thickness of the colored adhesive layer 11 is as described above, the processability is good, and appearance defects due to squeeze marks are less likely to occur. Further, the above optical properties are easily satisfied in relation to the content of the colorant (C). The colored adhesive layer 11 may be formed of a single layer or may be formed by stacking a plurality of layers.

1-2. Release sheet

The

release sheets

12a and 12b protect the colored adhesive layer 11 until the colored adhesive sheet 1 is used, and are released when the colored adhesive sheet 1 (colored adhesive layer 11) is used. In the colored adhesive sheet 1 of the present embodiment, one or both of the

release sheets

12a and 12b are not essential.

Examples of the

release sheets

12a and 12b include a polyethylene film, a polypropylene film, a polybutylene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, a vinyl chloride copolymer film, a polyethylene terephthalate film, a polyethylene naphthalate film, a polybutylene terephthalate film, a polyurethane film, an ethylene-vinyl acetate film, an ionomer resin film, an ethylene- (meth) acrylic acid copolymer film, an ethylene- (meth) acrylate copolymer film, a polystyrene film, a polycarbonate film, a polyimide film, and a fluororesin film. In addition, crosslinked films of these films may also be used. Further, a laminated film of these films may be used.

The release surfaces (particularly, the surfaces in contact with the colored adhesive layer 11) of the

release sheets

12a and 12b are preferably subjected to a release treatment. Examples of the release agent used for the release treatment include alkyd based, silicone based, fluorine based, unsaturated polyester based, polyolefin based, and wax based release agents. Of the

release sheets

12a and 12b, one release sheet is preferably a heavy release type release sheet having a large release force, and the other release sheet is preferably a light release type release sheet having a small release force.

The thickness of the

release sheets

12a and 12b is not particularly limited, but is usually about 20 to 150 μm.

2. Physical Properties (adhesive force)

The lower limit of the adhesive force of the colored adhesive sheet 1 of the present embodiment to soda-lime glass is preferably 1N/25mm or more, more preferably 2N/25mm or more, particularly preferably 4N/25mm or more, and further preferably 8N/25mm or more. When the lower limit of the adhesive force is as described above, the step following property under high temperature and high humidity conditions is more excellent. The upper limit of the adhesion force of the colored adhesive sheet 1 of the present embodiment to soda-lime glass is preferably 80N/25mm or less, more preferably 50N/25mm or less, and particularly preferably 30N/25mm or less. When the upper limit value of the adhesive force is set as described above, excellent reworkability can be obtained, and the display body constituting member, particularly an expensive display body constituting member, can be reused when a bonding error occurs.

Here, the adhesive force in the present specification means an adhesive force measured substantially by a 180-degree peel method according to JIS Z0237:2009, and is a value measured by making a measurement sample 25mm wide and 100mm long, pressing the measurement sample on an adherend at 0.5MPa and 50 ℃ for 20 minutes, then leaving the measurement sample under conditions of normal pressure, 23 ℃ and 50% RH for 24 hours, and then measuring a peel speed of 300 mm/minute. When the adhesive is an active energy ray-curable adhesive, the adhesive is an adhesive force of a colored adhesive layer cured by an active energy ray after being attached to an adherend. In addition, from the viewpoint of adhesiveness to an adherend and reworkability, when the adhesive is an active energy ray-curable adhesive, the adhesive force of the adhesive before curing with an active energy ray is preferably 1 to 80N/25mm, particularly preferably 2 to 50N/25mm, and more preferably 4 to 30N/25 mm.

3. Production of colored adhesive sheet

As one example of producing the colored adhesive sheet 1, a coating solution of the above-mentioned adhesive composition P is applied to the release surface of one release sheet 12a (or 12b), heat treatment is performed to thermally crosslink the adhesive composition P to form a coating layer, and then the coating layer is laminated to the release surface of the other release sheet 12b (or 12 a). When the curing period is required, the coating layer becomes the colored adhesive layer 11 by providing the curing period, and when the curing period is not required, the coating layer directly becomes the adhesive layer 11. Thus, the colored adhesive sheet 1 can be obtained. The conditions for heat treatment and aging are as described above.

As another production example of the colored adhesive sheet 1, a coating solution of the above-mentioned adhesive composition P is applied to the release surface of one release sheet 12a, and heat treatment is performed to thermally crosslink the adhesive composition P to form a coating layer, thereby obtaining a release sheet 12a with a coating layer. Further, the coating solution of the adhesive composition P is applied to the release surface of the other release sheet 12b, and heat treatment is performed to thermally crosslink the adhesive composition P to form a coating layer, thereby obtaining a release sheet 12b with a coating layer. Then, the coated release sheet 12a and the coated release sheet 12b are bonded to each other so that the two coated layers are in contact with each other. Here, a plurality of coated release sheets may be produced, and a desired number of the coated layers may be attached. When the curing period is required, the laminated coating layer becomes the colored adhesive layer 11 by providing the curing period, and when the curing period is not required, the laminated coating layer directly becomes the colored adhesive layer 11. Thus, the colored adhesive sheet 1 can be obtained. According to this production example, even when the colored adhesive layer 11 is thick, stable production can be performed.

As a method for applying the coating solution of the adhesive composition P, for example, a bar coating method, a blade coating method, a roll coating method, a doctor blade coating method, a die coating method, a gravure coating method, or the like can be used.

[ display body ]

Examples of the types of display bodies (displays) in the present embodiment include display bodies for vehicles such as instrument panels of automobiles, car navigation systems, and various meters of consoles, display bodies for tablet terminals used by general users, display bodies for commercial tablet terminals, digital signage, and the like, and display bodies for outdoor digital signage, and the like. These display bodies are sometimes required to have appearance coordination with surrounding members, a high-grade feeling, and the like. However, the display body of the present invention is not limited thereto.

As shown in fig. 2, the display 2 of the present embodiment includes a first display component 21 (one display component), a second display component 22 (the other display component), and a colored adhesive layer 11, and the colored adhesive layer 11 is located between the first display component 21 and the second display component 22, and the first display component 21 and the second display component 22 are bonded to each other.

At least one of the first display element constituting member 21 and the second display element constituting member 22 may have a step on at least the surface of the side to be bonded with the colored adhesive layer 11. In the present embodiment shown in fig. 2, the first display element constituting member 21 has a step such as a printed layer 3 on the surface on the side of the colored adhesive agent layer 11.

The colored adhesive layer 11 in the display 2 is the colored adhesive layer 11 of the colored adhesive sheet 1.

Examples of the display 2 include a Liquid Crystal Display (LCD) display, a Light Emitting Diode (LED) display, an organic electroluminescence (organic EL) display, and electronic paper, and may be a touch panel.

The first display element constituting member 21 is preferably a protective panel made of a laminate including a glass plate, a plastic plate, and the like, in addition to the glass plate, the plastic plate, and the like. In this case, the printed layer 3 is usually formed in a frame shape on the colored adhesive agent layer 11 side of the first display element constituting member 21.

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

The plastic plate is not particularly limited, and examples thereof include acrylic plates and polycarbonate plates. The thickness of the plastic sheet is not particularly limited, but is usually 0.2 to 5mm, preferably 0.4 to 3 mm.

Further, various functional layers (a transparent conductive film, a metal layer, a silica layer, a hard coat layer, an antiglare layer, etc.) may be provided on one surface or both surfaces of the glass plate or the plastic plate, and an optical member may be laminated. In addition, the transparent conductive film and the metal layer may also be patterned.

The second display body constituting member 22 is preferably an optical member to be attached to the first display body constituting member 21, a display body module (for example, a Liquid Crystal (LCD) module, a Light Emitting Diode (LED) module, an organic electroluminescence (organic EL) module, or the like), an optical member as a part of the display body module, or a laminate including the display body module.

Examples of the optical member include an anti-scattering film, a polarizing plate (polarizing film), a polarizer, a retardation plate (retardation film), a viewing angle compensation film, a brightness enhancement film, a contrast enhancement film, a liquid crystal polymer film, a diffusion film, a semi-transmitting/reflecting film, and a transparent conductive film. Examples of the anti-scattering film include a hard coat film in which a hard coat layer is formed on one surface of a base film.

The material constituting the printed layer 3 is not particularly limited, and a known material for printing can be used. The lower limit of the thickness of the printed layer 3, that is, 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 value to the above value, it is possible to sufficiently ensure concealment of the electric wiring lines and the like from the observer side. The upper limit is preferably 50 μm or less, more preferably 35 μm or less, particularly preferably 25 μm or less, and further preferably 20 μm or less. By setting the upper limit to the above value or less, deterioration in the step difference following property of the colored adhesive layer 11 to the print layer 3 can be prevented.

In order to manufacture the display 2, one release sheet 12a of the colored adhesive sheet 1 is peeled off, and the colored adhesive layer 11 exposed on the colored adhesive sheet 1 is bonded to the surface of the first display component member 21 on the side where the printed layer 3 is present, as an example.

Then, the other release sheet 12b is peeled off from the colored adhesive layer 11 of the colored adhesive sheet 1, and the colored adhesive layer 11 exposed in the colored adhesive sheet 1 and the second display constituent member 22 are bonded. As another example, the order of bonding the first display body constituting member 21 and the second display body constituting member 22 may be changed.

When the colored adhesive layer 11 is active energy ray-curable, the first display structure constituting member 21 and the second display structure constituting member 22 are bonded via the colored adhesive layer 11 as described above, and then the colored adhesive layer 11 is irradiated with an active energy ray. Thereby, the energy ray-curable component (C) in the colored adhesive layer 11 is polymerized, and the colored adhesive layer 11 is cured. The irradiation of the colored adhesive layer 11 with an energy ray is usually performed through either the first display element constituting member 21 or the second display element constituting member 22, and preferably through the first display element constituting member 21 as a protective panel.

The active energy ray is an active energy ray having an energy quantum in an electromagnetic wave or a charged particle beam, and specifically, an ultraviolet ray, an electron beam, or the like can be mentioned. Among the active energy rays, ultraviolet rays which are easy to handle are particularly preferable.

The ultraviolet irradiation may be carried out using a high-pressure mercury lamp, fusion H lamp (fusion H lamp), xenon lamp, or the like, and the amount of ultraviolet irradiation is preferably 50 to 1000mW/cm in terms of illuminance²About, preferably 100 to 500mW/cm²Left and right. In addition, the light quantity is preferably 50 to 10000mJ/cm²More preferably 200 to 7000mJ/cm²Particularly preferably 500 to 3000mJ/cm². On the other hand, the electron beam irradiation may be performed by using an electron beam accelerator or the like, and the irradiation amount of the electron beam is preferably about 10 to 1000 krad.

Here, as shown in fig. 3, the display body 2 of the present embodiment preferably has a frame member 4 in the peripheral portion of the display body 2. The frame member 4 is preferably black. The preferred ranges of lightness L, chroma a, and chroma b defined by the CIE1976L a b color system, which is the hue of the frame member 4, are the same as the hue of the peripheral member. By providing the frame member 4 with such a color tone, the frame member can be easily recognized by the naked eye as a frame member having a visually high-class feeling. Further, by providing the frame member 4 with the color tone described above, the colored adhesive layer 11 of the present embodiment has a stronger sense of unity with the frame member 4, and the appearance compatibility is further improved.

The physical properties of the colored adhesive layer 11 suppress the whitening of the display 2 when the display is turned off, and improve the design. This gives a sense of unity with the black frame member 4, for example, and provides excellent appearance compatibility. Further, the display 2 ensures visibility as a display.

Further, in the display 2, when the colored adhesive layer 11 is formed of the adhesive composition P, the colored adhesive layer 11 is excellent in step following property under high temperature and high humidity conditions, and therefore, for example, even when the display 2 is left under high temperature and high humidity conditions (for example, 85 ℃ and 85% RH), occurrence of floating, peeling, and the like in the vicinity of the step can be suppressed.

The level difference following ability can be judged by using the level difference following rate (%) as an index. The lower limit value of the step following ratio (%) of the colored adhesive layer 11 represented by the following formula is preferably 10% or more, more preferably 20% or more, particularly preferably 40% or more, and further preferably 60% or more. The upper limit of the level difference following rate is not particularly limited, but is usually preferably 80% or less, and particularly preferably 70% or less.

The step following ratio (%) (step height (μm) in which the embedded state is maintained without air bubbles, floating, peeling, or the like after the predetermined durability test)/(thickness of the colored adhesive layer) } × 100

The test method of the stepped portion following ratio is shown in test examples described later.

The embodiments described above are described for easy understanding of the present invention, and are not described for limiting the present invention. Therefore, the elements disclosed in the above embodiments also cover all design changes and equivalents that fall within the technical scope of the present invention.

For example, either one or both of the

release sheets

12a and 12b in the colored adhesive sheet 1 may be omitted, and a desired optical member may be laminated instead of the release sheet 12a and/or 12 b. Further, the first display body constituting member 21 may not have a level difference. Further, not only the first display element constituting member 21 but also the second display element constituting member 22 may have a step difference on the side of the colored adhesive agent layer 11.

Examples

The present invention will be described in more detail with reference to examples and the like, but the scope of the present invention is not limited to these examples and the like.

[ example 1]

Preparation of (meth) acrylate polymers

The (meth) acrylate polymer (a) was prepared by copolymerizing 70 parts by mass of 2-ethylhexyl acrylate, 15 parts by mass of methyl methacrylate, and 15 parts by mass of 2-hydroxyethyl acrylate by a solution polymerization method. The molecular weight of the (meth) acrylate polymer (a) was measured by the method described later, and the weight average molecular weight (Mw) was 80 ten thousand.

2. Preparation of adhesive composition

100 parts by mass (in terms of solid content; the same applies hereinafter) of the (meth) acrylic acid ester polymer (A) obtained in the above step 1, 0.2 parts by mass of trimethylolpropane-modified toluene diisocyanate (TOYOCHEMCO., LTD., product name "BHS 8515") as a crosslinking agent (B), 0.4 parts by mass of carbon black-based black pigment (C1) as a colorant (C), and 0.2 parts by mass of 3-glycidoxypropyltrimethoxysilane as a silane coupling agent were mixed, sufficiently stirred, and diluted with methyl ethyl ketone, thereby obtaining a coating solution of the adhesive composition.

Table 1 shows the respective compounding ratios (solid content equivalent) of the adhesive compositions when the (meth) acrylate polymer (a) is 100 parts by mass (solid content equivalent). The abbreviations shown in table 1 are as follows.

[ (meth) acrylic ester Polymer (A) ]

2 EHA: 2-ethylhexyl acrylate

MMA: methacrylic acid methyl ester

HEA: 2-Hydroxyethyl acrylate

IBXA: acrylic acid isobornyl ester

ACMO: n-acryloyl morpholine

BA: acrylic acid n-butyl ester

AA: acrylic acid

[ colorant (C) ]

C1-C6: carbon black pigment having physical properties shown in Table 2

3. Production of colored adhesive sheet

The coating solution of the adhesive composition obtained in the above step 2 was coated on the release-treated surface of a heavy release type release sheet (manufactured by linetec corporation, product name "SP-PET 752150") which had been subjected to a release treatment on one surface of a polyethylene terephthalate film using a silicone-based release agent, using a blade coater, and then heat-treated at 90 ℃ for 1 minute to form a coating layer (thickness: 50 μm). Further, the coating solution of the adhesive composition obtained in the above step 2 was coated on the release-treated surface of a light release type release sheet (manufactured by Lintec Corporation, product name "SP-PET 381130") which had been subjected to a release treatment on one surface of a polyethylene terephthalate film using a silicone based release agent, and then heat-treated at 90 ℃ for 1 minute to form a coating layer (thickness: 50 μm) similarly using a blade coater.

Then, the obtained heavy release sheet with a coating layer and the obtained light release sheet with a coating layer were bonded so that both coating layers were in contact with each other, and the resultant sheets were aged at 23 ℃ and 50% RH for 7 days to prepare a colored adhesive sheet composed of a heavy release sheet/a colored adhesive layer (thickness: 100 μm)/a light release sheet.

The thickness of the colored adhesive layer is a value measured by using a constant pressure thickness measuring instrument (teclockco, ltd., product name "PG-02") in accordance with JIS K7130.

Examples 2 to 8 and comparative examples 1 to 2

Colored adhesive sheets were produced in the same manner as in example 1, except that the kind and ratio of each monomer constituting the (meth) acrylate polymer (a), the weight average molecular weight (Mw) of the (meth) acrylate polymer (a), the kind and blending amount of the colorant (C), the blending amount of the silane coupling agent, and the thickness of the colored adhesive layer were changed as shown in table 1. In example 5, 5.0 parts by mass of caprolactone-modified tris (2-acryloyloxyethyl) isocyanurate (SHIN-NAKAMURA CHEMICAL co., ltd., product name "NK ester a-9300-1 CL") as the active energy ray-curable component (D) and 0.5 parts by mass of 2,4, 6-trimethylbenzoyl-diphenyl-phosphine oxide as the photopolymerization initiator (E) were further added to obtain an active energy ray-curable adhesive. In comparative example 1, although the colorant (C) was not used, the terms of the colored adhesive layer and the colored adhesive sheet were used for convenience.

Further, colored adhesive sheets of examples 3 to 8 and comparative examples 1 to 2 were produced in the following manner. A coating solution of the adhesive composition prepared in the same manner as in example 1 was coated on the release-treated side of a heavy release type release sheet (manufactured by linetec corporation, product name "SP-PET 752150") which had been release-treated on one side of a polyethylene terephthalate film using a silicone-based release agent, using a knife coater, and then heat-treated at 90 ℃ for 1 minute to form a coating layer. The surface on the coating layer side of the obtained heavy release sheet with the coating layer was bonded to the release-treated surface of a light release sheet (product name "SP-PET 381130" manufactured by linetec corporation) obtained by subjecting one surface of a polyethylene terephthalate film to release treatment using a silicone-based release agent, and the sheet was aged at 23 ℃ and 50% RH for 7 days to prepare a colored adhesive sheet having a composition of the heavy release sheet/the colored adhesive layer/the light release sheet.

The weight average molecular weight (Mw) is a polystyrene-equivalent weight average molecular weight measured by Gel Permeation Chromatography (GPC) under the following conditions (GPC measurement).

< measurement conditions >

GPC measurement apparatus: HLC-8020 manufactured by TOSOH CORPORATION

GPC column (passage in the following order): TOSOH CORPORATION, Inc

TSK guard column HXL-H

TSK gel GMHXL(×2)

TSK gel G2000HXL

Determination of the solvent: tetrahydrofuran (THF)

Measurement temperature: 40 deg.C

[ test example 1] (measurement of haze value of colorant Diluent)

A solution obtained by diluting the colorant C1-C6 by 1 ten thousand times with ethyl acetate was measured for haze value (%) using a haze meter (NIPPON DENSHOKU INDUSTRIES Co., LTD., product name "SH-7000", optical path length 10mm) in accordance with JIS K7136: 2000. From the measurement values, the difference between the haze value at a wavelength of 780nm and the haze value at a wavelength of 380nm, the average haze which is the average of the haze value at a wavelength of 780nm and the haze value at a wavelength of 380nm, and the standard deviation of the haze values at the wavelengths in the wavelength region of 380nm to 780nm at a 5nm pitch were calculated. These results are shown in table 2.

[ test example 2] (measurement of gel fraction)

The colored adhesive sheets obtained in examples and comparative examples were cut into 80mm × 80mm sizes, the colored adhesive layer was wrapped in a polyester mesh (mesh size 200), the mass was weighed using a precision balance, and the mass of the mesh alone was subtracted to calculate the mass of the adhesive itself. The mass at this time was designated as M1.

Subsequently, the adhesive wrapped in the polyester net was immersed in ethyl acetate at room temperature (23 ℃ C.) for 24 hours. Then, the adhesive was taken out, air-dried at a temperature of 23 ℃ and a relative humidity of 50% for 24 hours, and further dried in an oven at 80 ℃ for 12 hours. After drying, the mass was weighed with a precision balance, and the mass of the adhesive itself was calculated by subtracting the mass of the net alone. The mass at this time was designated as M2. The gel fraction (%) was expressed as (M2/M1). times.100. The results are shown in Table 3.

In addition, with respect to the colored adhesive sheet of example 5, a plastic sheet (manufactured by inc., product name "iupulon-sheet MR 58U", thickness: 0.7mm, containing an ultraviolet absorber) in which a polymethyl methacrylate (PMMA) layer was laminated on a polycarbonate resin (PC) sheet was laminated on a light-release type release sheet, and the colored adhesive layer was cured by irradiating active energy rays through the plastic sheet under the following conditions. The gel fraction (after UV) of the adhesive of the cured colored adhesive layer was also derived in the same manner as described above.

< conditions for irradiation with active energy ray >

Using high-pressure mercury lamps

Illuminance of 200mW/cm²Light quantity 2000mJ/cm²

UV illuminance photometer used "UVPF-A1" manufactured by Eye graphics Co., Ltd "

[ test example 3] (measurement of storage modulus)

The release sheet was peeled from the colored adhesive sheets obtained in examples and comparative examples, and a plurality of colored adhesive layers were laminated so that the thickness thereof became 3 mm. A cylindrical body (height: 3mm) having a diameter of 8mm was punched out of the laminate of the obtained colored adhesive layer, and this was used as a sample.

The storage modulus (MPa) of the above sample was measured by the torsional shear method under the following conditions in accordance with JIS K7244-6 using a viscoelasticity measuring apparatus (manufactured by Physica, product name "MCR 300"). The results are shown in Table 3.

Measuring frequency: 1Hz

Measuring temperature: 23 deg.C

In addition, the colored adhesive sheet of example 5 was cured by irradiation with active energy rays in the same manner as in test example 2, and the storage modulus (after UV) of the cured colored adhesive layer was also measured in the manner described above.

[ test example 4] (measurement of haze value)

The colored adhesive layer of the colored adhesive sheet obtained in examples and comparative examples was measured for haze value (%) using a haze meter (NIPPON DENSHOKU INDUSTRIES co., ltd., product name "SH-7000") according to JIS K7136: 2000. The obtained total light haze value (%) is shown in table 3. Further, an average haze as an average value of the haze value at a wavelength of 780nm and the haze value at a wavelength of 380nm, a difference value between the haze value at a wavelength of 780nm and the haze value at a wavelength of 380nm, and a standard deviation of the haze values at respective wavelengths of 5nm intervals of 380nm to 780nm in the wavelength region were calculated from the measurement values.

In addition, the colored adhesive sheet of example 5 was cured by irradiation with active energy rays in the same manner as in test example 2, and the total light haze value (after UV) of the cured colored adhesive layer was measured in the manner described above. Then, the average haze (after UV) as an average value of the haze value at a wavelength of 780nm and the haze value at a wavelength of 380nm, the difference (after UV) between the haze value at a wavelength of 780nm and the haze value at a wavelength of 380nm, and the standard deviation (after UV) of the haze value at each wavelength of a 5nm interval of a wavelength region of 380nm to 780nm were calculated from the measurement values. The results are shown in Table 3.

[ test example 5] (measurement of Total light transmittance)

The colored adhesive layer of the colored adhesive sheet obtained in examples and comparative examples was bonded to glass, and this was used as a sample for measurement. The total light transmittance (%) of the above-mentioned measurement sample was measured using a haze meter (NIPPON DENSHOKU INDUSTRIES Co., LTD., manufactured by LTD., product name "SH-7000") in accordance with JIS K7361-1:1997 on the basis of background measurement (background measurement) using glass. In addition, the colored adhesive sheet of example 5 was cured by irradiation with active energy rays in the same manner as in test example 2, and the total light haze value (after UV) of the cured colored adhesive layer was measured in the manner described above. The results are shown in Table 3.

[ test example 6] (measurement of L.a.b.)

The colored adhesive layer of the colored adhesive sheet obtained in examples and comparative examples was measured for lightness L, chroma a, and chroma b defined in the color system by CIE1976L a b using a simultaneous photometric colorimeter (NIPPON DENSHOKU INDUSTRIES co., ltd., product name "SQ 2000"). In addition, the colored adhesive sheet of example 5 was irradiated with active energy rays to cure the colored adhesive layer in the same manner as in test example 2, and the lightness L (after UV), the chroma a (after UV), and the chroma b (after UV) of the cured colored adhesive layer were measured in the above manner. The results are shown in Table 3.

[ test example 7] (measurement of adhesive force)

A light release type release sheet was peeled from each of the colored adhesive sheets obtained in examples and comparative examples, and the exposed colored adhesive layer was bonded to an easy adhesive layer of a polyethylene terephthalate (PET) film (TOYOBO co., ltd., product name "PET a 4300" having a thickness of 100 μm) having an easy adhesive layer, to obtain a release sheet/colored adhesive layer/PET film laminate. The obtained laminate was cut into a width of 25mm and a length of 100mm to obtain a sample.

The heavy-release type release Sheet was peeled from the sample at 23 ℃ and 50% RH, and the exposed colored adhesive layer was attached to soda-lime Glass (manufactured by Nippon Sheet Glass co., ltd.), followed by pressurization at 0.5MPa and 50 ℃ for 20 minutes using an autoclave manufactured by kurihara manual co., ltd. Then, after leaving at 23 ℃ and 50% RH for 24 hours, the adhesion (N/25mm) was measured under the conditions of a peel speed of 300 mm/min and a peel angle of 180 degrees using a tensile tester (manufactured by ORIENTEC CORPORATION, product name "TENSILON"). The conditions not described herein were measured according to JIS Z0237: 2009. The results are shown in Table 3.

In addition, with respect to the colored adhesive sheet of example 5, the colored adhesive layer was attached to soda-lime glass in the same manner as described above, and after the autoclave treatment, the sheet was left to stand at 23 ℃ and 50% RH for 24 hours, and then the colored adhesive layer was cured by irradiating with an active energy ray in the same manner as in test example 2, and the adhesive force (after UV) of the cured colored adhesive layer was also measured in the same manner as described above.

[ test example 8] (measurement of step following Rate)

An ultraviolet curable ink (Teikoku printing inks Mfg. Co., manufactured by Ltd., product name "POS-911 ink") was screen-printed in a frame shape (outer shape: 90mm in length × mm in width 50mm in width 5mm) on the surface of a glass plate (manufactured by NSG Precision Cells, Inc., product name "burning glass eagleXG", 90mm in length × mm in width 50mm × mm in thickness 0.5mm), and then ultraviolet rays (80W/cm in width) were irradiated²2 metal halogen lamps with a height of 15cm and a belt speed of 10-15 m/min) to cure the printed ultraviolet raysThe chemical conversion ink was cured to prepare a glass plate having a step difference (height of step difference: any one of 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 50 μm, 60 μm and 70 μm) by printing.

The light-release type release sheet was peeled from the colored adhesive sheets obtained in examples and comparative examples, and the exposed colored adhesive layer was bonded to an easy-adhesion layer of a polyethylene terephthalate film (TOYOBO CO., LTD., product name "PET A4300" with a thickness of 100 μm) having an easy-adhesion layer. Then, the heavy-release type release sheet is peeled off to expose the colored adhesive layer. Then, the laminate was laminated on glass plates having different steps so that the frame-shaped printing surface was entirely covered with the colored adhesive layer using a laminator (product name "LPD 3214" manufactured by fujiapla inc.) to obtain a sample for evaluation.

The obtained sample for evaluation was autoclaved at 50 ℃ under 0.5MPa for 30 minutes and then left at 23 ℃ under 50% RH for 24 hours. Subsequently, the film was stored under high temperature and high humidity conditions of 85 ℃ and 85% RH for 72 hours (durability test), and then the step following property was evaluated. The level difference following property was judged by whether or not the printing level difference was completely embedded in the colored adhesive layer, and it was judged that the printing level difference could not be followed when bubbles, floating, peeling, and the like were observed at the interface between the printing level difference and the colored adhesive layer. Here, the level difference following property was evaluated by a level difference following rate (%) shown by the following formula. The results are shown in Table 3.

The step following ratio (%) (step height (μm) in which the embedded state is maintained without air bubbles, floating, peeling, or the like after the durability test)/(thickness of the colored adhesive layer) x 100)

In addition, with respect to the colored adhesive sheet of example 5, a colored adhesive sheet in which the thickness of the colored adhesive layer was set to 25 μm was prepared, the sample for evaluation obtained in the same manner as described above was subjected to a heat-pressing treatment, and then left for 24 hours at 23 ℃ and 50% RH, and then the colored adhesive layer was cured by irradiation with an active energy ray in the same manner as in test example 2. The cured colored adhesive layer was measured for the step following ratio (after UV) in the same manner as described above.

[ test example 9] (evaluation of design)

The colored adhesive sheets obtained in examples and comparative examples were cut to a length of 70mm × a width of 70mm, and the colored adhesive layers of the colored adhesive sheets were bonded so as to be sandwiched between two pieces of soda-lime Glass (manufactured by Nippon Sheet Glass co., ltd., length of 70mm × width of 70mm × thickness of 1.1mm), and these were used as samples. In addition, the colored adhesive sheet of example 5 was used as a sample by curing the colored adhesive layer by irradiation with active energy rays in the same manner as in test example 2.

The resulting sample was placed directly in front of a display for a light-out condition (manufactured by Fujitsu Limited, product name "LITEBOOK A574/H", size 15.6 inches, resolution 1366X 768). At this time, the sample is disposed so that the peripheral portion of the sample is adjacent to the frame material of the display. Then, the color tone (blackening or whitening) of the sample was visually judged under a three-wavelength fluorescent lamp (distance from the fluorescent lamp: 200cm), and the design of the screen color tone was evaluated by the following criteria. The results are shown in Table 3.

Very good: having a darker black color even under fluorescent lamp reflection.

O: if there is no fluorescent lamp reflection, it has a darker black color.

X: overall blushing was observed.

Further, the visual appearance (see え side) of the boundary between the sample portion and the frame material of the display was judged by the naked eye, and the design property with respect to the seamless property was evaluated by the following criteria. The results are shown in Table 3.

Very good: no boundary can be identified.

O: the boundaries are slightly recognized, but not obvious.

X: the boundary can be clearly identified.

Further, the color tone (CIE1976L a b color system) of the frame material of the display was measured using a spectrophotometer (product name "Spectro-Guide" manufactured by BYK corporation), and as a result, L: 19.7, a: -0.3, b: -1.5.

[ test example 10] (evaluation of visibility)

The sample produced in the same manner as in test example 9 was placed directly in front of a display in a lighted state (manufactured by fujitsu limited, product name "LITEBOOK a 574/H", size 15.6 inches, resolution 1366 × 768). At this time, ARIB multi-format color bars (Multiformat color bar) are displayed on the display. Then, visual expression of the display through the sample was visually judged from the front and the inclined surface (angle of 45 ℃) under a three-wavelength fluorescent lamp (distance from the fluorescent lamp: 200cm), and visibility (wide-angle visibility) was evaluated according to the following criteria. The results are shown in Table 3.

Very good: the visual appearance observed from the front was unchanged from that observed from the inclined plane.

O: the visual appearance observed from the inclined plane was darker than that observed from the front surface, but the color tone was unchanged.

X: the visual expression observed from the front side and the visual expression observed from the inclined side have a change in hue.

In either case, the screen is bright when viewed from the front, and therefore the visibility of the image is good depending on the screen brightness.

[ Table 1]

[ Table 2]

As is clear from table 3, the display using the colored pressure-sensitive adhesive sheet obtained in the examples is excellent in design (particularly, in design with respect to color tone of a screen) and visibility (particularly, wide-angle visibility and visibility depending on screen brightness). Further, the colored adhesive sheets obtained in the examples were also excellent in step following property.

Industrial applicability

The colored adhesive sheet of the present invention can be suitably used, for example, for bonding display body constituent members to each other in a display body having a black frame material, and particularly, for bonding a protective panel having a step difference to a desired display body constituent member.

Claims

1. A colored adhesive sheet comprising a colored adhesive layer composed of an adhesive containing a colorant for bonding one display constituent member to another display constituent member, wherein the average haze of the average of the haze value at a wavelength of 780nm and the haze value at a wavelength of 380nm of the colored adhesive layer is 1% or more and 60% or less.

2. The colored adhesive sheet according to claim 1, wherein the difference between the haze value at a wavelength of 780nm and the haze value at a wavelength of 380nm in the colored adhesive layer is 15% or less.

3. The colored adhesive sheet according to claim 1, wherein the standard deviation of the haze value in the wavelength region of the colored adhesive layer at each wavelength of a 5nm pitch of 380nm to 780nm is 5 or less.

4. The colored adhesive sheet according to claim 1, wherein the colored adhesive layer has a total light transmittance of 10% or more and less than 95%, and the colored adhesive layer has a chromaticity a and a chromaticity b defined by the CIE1976L a b color system of-7 to 7, respectively.

5. The colored adhesive sheet according to claim 1, wherein the average haze value, which is the average of the haze value at a wavelength of 780nm and the haze value at a wavelength of 380nm, of a solution obtained by diluting the colorant with ethyl acetate by 1 ten thousand times is 1% or more and 60% or less.

6. The colored adhesive sheet according to claim 1, wherein a difference between a haze value at a wavelength of 780nm and a haze value at a wavelength of 380nm in a solution obtained by diluting the colorant with ethyl acetate by 1 ten thousand times is 30 percentage points or less.

7. The colored adhesive sheet according to claim 1, wherein the colorant is a black pigment.

8. The colored adhesive sheet according to claim 1, wherein the adhesive is an acrylic adhesive.

9. A colored adhesive sheet according to claim 1, wherein the adhesive is obtained by crosslinking an adhesive composition containing a (meth) acrylate polymer (a), a crosslinking agent (B) and a colorant (C).

10. The colored adhesive sheet according to claim 1, which comprises: two release sheets, and the colored adhesive layer sandwiched between the release sheets so as to be in contact with release surfaces of the two release sheets.

11. A display body, comprising: one display structure constituting member, another display structure constituting member, and a colored adhesive layer for bonding the one display structure constituting member and the another display structure constituting member to each other, wherein the colored adhesive layer is the colored adhesive layer of the colored adhesive sheet according to any one of claims 1 to 10.

12. The display according to claim 11, wherein at least one of the one display component and the other display component has a level difference at least on a surface on a side to be bonded with the colored adhesive layer.

13. The display according to claim 11, wherein the display has a black frame material.