JP7336348B2 - Display and adhesive sheet - Google Patents

Description

TECHNICAL FIELD The present invention relates to a display and an adhesive sheet used for the display.

In recent years, displays such as televisions, monitors for personal computers, digital signage, smartphones, and tablet terminals have used image display devices such as liquid crystal display devices and organic electroluminescence (organic EL) devices. There are many things.

In the display body as described above, when the display body is turned off, it is sometimes required to give a sense of unity with the peripheral member of the display body, for example, the frame material, and to improve the design. For that purpose, it is conceivable to color the display. A technique related to coloring of the display is disclosed in Patent Document 1, for example.

JP-A-2005-82634

However, since the adhesive sheet disclosed in Patent Document 1 is colored for the purpose of light shielding and light hiding properties, when used on the viewer side rather than the liquid crystal module or the organic EL module, the visibility of the displayed image is reduced. cannot be guaranteed.

The present invention has been made in view of the actual situation as described above, and an object of the present invention is to provide an adhesive sheet capable of improving the design of a display and a display with improved design.

In order to achieve the above objects, firstly, the present invention provides a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer for bonding one display body constituent member and another display body constituent member, the adhesive sheet conforming to CIE1976L*. The pressure-sensitive adhesive layer has a color difference ΔE* of less than 95 from perfectly white, as defined by the a*b* color system, and the pressure-sensitive adhesive layer has a total light transmittance of 10% or more. A pressure-sensitive adhesive sheet characterized by the following is provided (Invention 1).

In the above invention (Invention 1), the color difference ΔE* of the pressure-sensitive adhesive layer is the above, so that when the display is turned off, the appearance harmony with the white peripheral member is achieved, and the design is improved. . In the above invention (invention 1), since the total light transmittance of the pressure-sensitive adhesive layer is as above, it is possible to ensure the visibility of the image/video when the display is lit.

In the above invention (invention 1), the adhesive layer preferably has a haze value of 0.5% or more and 100% or less (invention 2).

In the above inventions (inventions 1 and 2), the pressure-sensitive adhesive layer preferably comprises a pressure-sensitive adhesive containing a white colorant (invention 3).

In the above inventions (inventions 1 to 3), the content of the white colorant in the adhesive is preferably 0.01% by mass or more and 50% by mass or less (invention 4).

In the above inventions (inventions 1 to 4), the adhesive is preferably an acrylic adhesive (invention 5).

In the above inventions (inventions 1 to 5), the pressure-sensitive adhesive crosslinks the pressure-sensitive adhesive composition containing at least a (meth)acrylic acid ester polymer (A), a cross-linking agent (B) and a white colorant (C). (Invention 6).

In the above inventions (inventions 1 to 6), it is preferable to include two release sheets and the adhesive layer sandwiched between the release sheets so as to be in contact with the release surfaces of the two release sheets (invention 7).

Secondly, the present invention comprises one display body constituent member, another display body constituent member, and an adhesive layer for adhering the one display body constituent member and the other display body constituent member together. Provided is a display (Invention 8), wherein the pressure-sensitive adhesive layer is formed from the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet (Inventions 1 to 7).

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

In the above inventions (inventions 8 and 9), it is preferable to have a white peripheral member (invention 10).

According to the pressure-sensitive adhesive sheet of the present invention, it is possible to improve the designability of the display. Moreover, the display body according to the present invention has improved designability.

1 is a cross-sectional view of a pressure-sensitive adhesive sheet according to one embodiment of the present invention; FIG. 1 is a cross-sectional view of a display body according to an embodiment of the invention; FIG. 1 is a plan view of a display having a frame material according to one embodiment of the present invention; FIG.

Embodiments of the present invention will be described below.
[Adhesive sheet]
A pressure-sensitive adhesive sheet according to an embodiment of the present invention includes a pressure-sensitive adhesive layer for bonding one display body-constituting member and another display body-constituting member, and preferably one side of the pressure-sensitive adhesive layer Alternatively, release sheets are laminated on both sides. The display body and display body constituent members will be described later.

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

1. Each member 1-1. Adhesive layer The adhesive layer 11 of the adhesive sheet 1 according to the present embodiment has a color difference ΔE* from perfect white of less than 95 as defined by the CIE1976 L*a*b* color system, and a total light transmittance of is 10% or more.

なお、本明細書における明度Ｌ*、色度ａ*およびｂ*の測定方法（反射光測定）は、後述する試験例に示す通りである。 Perfect white defined by the CIE 1976 L*a*b* color system has a lightness L* of 100, a chromaticity a* of 0, and a chromaticity b* of 0. Therefore, when the measured value of lightness L* of the pressure-sensitive adhesive layer 11 is L*M, the measured value of chromaticity a* is a*M, and the measured value of b* is b*M, it is completely white. The color difference ΔE* is calculated by the following formula (I).

The method of measuring the lightness L*, the chromaticities a* and b* (reflected light measurement) in this specification is as shown in the test examples described later.

In the pressure-sensitive adhesive sheet 1 according to the present embodiment, since the color difference ΔE* of the pressure-sensitive adhesive layer 11 is as described above, when the display body is turned off, white peripheral members such as a white frame member, a white wall, and a white printed portion etc., and the design is improved. It should be noted that the white color of the peripheral member does not have to be the "perfect white color" described above.

Further, in the adhesive sheet 1 according to the present embodiment, since the total light transmittance of the adhesive layer 11 is 10% or more, the visibility of the image/video can be ensured when the display member is lit. The total light transmittance in this specification is a value measured according to JIS K7361-1:1997.

The color difference ΔE* is required to be less than 95, preferably 80 or less, more preferably 60 or less, particularly 40 or less, from the viewpoint of appearance harmony with the white peripheral member. is preferred, and 35 or less is more preferred. The lower limit of the color difference ΔE* is not particularly limited, and the smallest value is 0, but considering the relationship with the total light transmittance, it is preferably 1 or more, more preferably 5 or more. In particular, it is preferably 10 or more, more preferably 20 or more.

The lightness L*M of the pressure-sensitive adhesive layer 11 is preferably 3 or more, more preferably 9 or more, particularly preferably 50 or more, further preferably 65 or more. Further, the lightness L*M is preferably 100 or less, more preferably 90 or less, particularly preferably 83 or less, further preferably 80 or less. The absolute value of the chromaticity a*M of the pressure-sensitive adhesive layer 11 is preferably 0 or more, particularly preferably 0.1 or more, further preferably 0.5 or more. The absolute value of the chromaticity a*M is preferably 10 or less, more preferably 5 or less, particularly preferably 2 or less, and further preferably 1.5 or less. . The absolute value of the chromaticity b*M of the pressure-sensitive adhesive layer 11 is preferably 0 or more, particularly preferably 0.1 or more. The absolute value of the chromaticity b*M is preferably 10 or less, more preferably 5 or less, particularly preferably 2 or less, and further preferably 1.5 or less. . As a result, the color difference ΔE* and the total light transmittance described above are easily satisfied, and a preferable color tone is obtained when the display is turned off.

The total light transmittance of the adhesive layer 11 is required to be 10% or more, preferably 20% or more, more preferably 30% or more, from the viewpoint of image/video visibility. In particular, it is preferably 40% or more, more preferably 45% or more. The upper limit of the total light transmittance is usually 100% or less, and considering the relationship with the color difference ΔE*, it is preferably 95% or less, more preferably 90% or less, and particularly 80%. or less, more preferably 70% or less, and most preferably 65% or less.

The haze value of the pressure-sensitive adhesive layer 11 is preferably 0.5% or more, more preferably 5% or more, particularly preferably 15% or more, further preferably 60% or more. , is more than 90%. This makes it easier to satisfy the above-mentioned color difference ΔE*, and makes it easier to impart a sense of unity with the white surrounding members to the resulting display. The upper limit of the haze value of the pressure-sensitive adhesive layer 11 is not particularly limited, but is preferably 100% or less, more preferably 99.9% or less, and particularly preferably 99.8% or less. , and more preferably 99.4% or less. The haze value in this specification is a value measured according to JIS K7136:2000.

The adhesive constituting the adhesive layer 11 preferably contains a white colorant, and by appropriately selecting the type and content of this white colorant, the color difference ΔE* and the total light transmittance (further haze value) can be achieved.

The white colorant may be mainly composed of a pigment, or may be mainly composed of a dye. The pigment may be an inorganic pigment or an organic pigment. Inorganic pigments are preferred from the viewpoint of the durability of the pressure-sensitive adhesive to be obtained.

The white colorant preferably contains, for example, inorganic pigments such as titanium oxide, zinc oxide, calcium carbonate, and aluminum oxide. Titanium and zinc oxide are more preferred, with titanium oxide being particularly preferred. These inorganic pigments may be subjected to surface treatment such as organic treatment, silicone treatment, and alumina treatment. One of the above inorganic pigments may be used alone, or two or more thereof may be used in combination.

In addition, the white colorant may contain colorless and transparent fine particles such as silica together with the inorganic pigment. This makes it easier to obtain an appropriate white color. In this case, the content of the colorless transparent fine particles is preferably 0.01 to 50% by mass, more preferably 0.1 to 30% by mass, particularly 1 to 20% by mass, in the white colorant. preferably 5 to 10% by mass.

The mode diameter (mode diameter) of the white colorant is preferably 2 nm or more, more preferably 10 nm or more, particularly preferably 100 nm or more, further preferably 200 nm or more. This makes it easier to satisfy the above color difference ΔE*. The mode diameter is preferably 3000 nm or less, more preferably 1000 nm or less, particularly preferably 800 nm or less, and further preferably 600 nm or less. This makes it easier to satisfy the above total light transmittance.

The median diameter (D50) of the white colorant is preferably 2 nm or more, more preferably 10 nm or more, particularly preferably 100 nm or more, further preferably 200 nm or more. This makes it easier to satisfy the above color difference ΔE*. The median diameter is preferably 3000 nm or less, more preferably 1000 nm or less, particularly preferably 800 nm or less, and further preferably 600 nm or less. This makes it easier to satisfy the above total light transmittance.

The mode diameter and median diameter of the white colorant in this specification are values measured by a dynamic light scattering method.

The content of the white colorant in the adhesive constituting the adhesive layer 11 is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and particularly 1% by mass or more. It is more preferable that the content is 3% by mass or more. As a result, the above color difference ΔE* is easily satisfied without making the pressure-sensitive adhesive layer too thick. In addition, the content is preferably 50% by mass or less, more preferably 30% by mass or less, particularly more preferably 20% by mass or less, and further preferably 15% by mass or less. More preferably, it is preferably 8% by mass or less from the standpoint of making the pressure-sensitive adhesive layer thin and having excellent conformability to unevenness. This makes it easier to satisfy the above total light transmittance.

The lower limit of the thickness of the pressure-sensitive adhesive layer 11 is preferably 3 μm or more, more preferably 10 μm or more, from the viewpoint that the aforementioned optical properties are easily satisfied in relation to the content of the white colorant. In particular, the thickness is preferably 20 μm or more, and more preferably 40 μm or more from the viewpoint of further improving the conformability to unevenness.

The upper limit of the thickness of the pressure-sensitive adhesive layer 11 is preferably 3000 μm or less, more preferably 1000 μm or less, particularly preferably 500 μm or less, further preferably 300 μm or less. When the upper limit value of the thickness of the pressure-sensitive adhesive layer 11 is above, the optical properties described above are easily satisfied in relation to the content of the white colorant. In addition, it is less likely that defects in appearance due to push marks or the like will occur.

The adhesive layer 11 may be formed as a single layer, or may be formed by laminating a plurality of layers. The thickness of the pressure-sensitive adhesive layer 11 in this specification is a value measured according to JIS K7130.

The type of adhesive constituting the adhesive layer 11 of the adhesive sheet 1 according to the present embodiment is not particularly limited, and examples include acrylic adhesives, polyester adhesives, polyurethane adhesives, rubber adhesives, silicone Any of adhesives such as adhesives may be used. The adhesive may be emulsion type, solvent type or non-solvent type, and may be crosslinked or non-crosslinked. Among them, acrylic pressure-sensitive adhesives are preferable because they have excellent adhesive physical properties, optical properties, and the like.

Further, the acrylic pressure-sensitive adhesive may be active energy ray-curable or non-active energy ray-curable. As the acrylic pressure-sensitive adhesive, a cross-linking type is preferable, and a thermal cross-linking type is more preferable.

Specifically, the adhesive is an adhesive composition (hereinafter referred to as "adhesive It may be referred to as "composition P".) is preferably crosslinked. Moreover, when using the said adhesive as an active-energy-ray-curable adhesive, it is preferable that the adhesive composition P contains an active-energy-ray-curable component (D) further.

A pressure-sensitive adhesive obtained from such pressure-sensitive adhesive composition P can exhibit excellent optical properties, adhesive strength, durability (step conformability under high-temperature and high-humidity conditions), and the like. In this specification, (meth)acrylic acid means both acrylic acid and methacrylic acid. The same applies to other similar terms. In addition, the concept of "copolymer" is also included in "polymer".

(1) Components of adhesive composition (1-1) (meth)acrylic acid ester polymer (A)
The (meth)acrylic acid ester polymer (A) in the present embodiment contains a reactive group-containing monomer having a reactive group that reacts with the cross-linking agent (B) in the molecule as a monomer unit constituting the polymer. is preferred. A reactive group derived from this reactive group-containing monomer reacts with the cross-linking agent (B) to form a cross-linked structure (three-dimensional network structure), thereby obtaining a pressure-sensitive adhesive having desired cohesion.

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 carboxy group in the molecule (carboxy group-containing monomer), a monomer having an amino group in the molecule (amino group-containing monomer ) and the like are preferably mentioned. Among these, a hydroxyl group-containing monomer or a carboxy group-containing monomer, which is excellent in reactivity with the cross-linking agent (B), is preferable, and a hydroxyl group-containing monomer and a carboxy group-containing monomer may be used in combination.

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

Carboxy group-containing monomers include, for example, ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. Among them, acrylic acid is preferable from the viewpoint of the reactivity of the carboxy group in the obtained (meth)acrylic acid ester polymer (A) with the cross-linking agent (B) and the copolymerizability with other monomers. These may be used alone or in combination of two or more.

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

The (meth)acrylic acid ester polymer (A) preferably contains a reactive group-containing monomer as a lower limit of 1% by mass or more, particularly 5% by mass or more, as a monomer unit constituting the polymer. is preferred, more preferably 10% by mass or more, and when the reactive group-containing monomer is only a hydroxyl group-containing monomer, the content is preferably 15% by mass or more, particularly 20% by mass or more. preferable. In addition, the (meth)acrylic acid ester polymer (A) preferably contains a reactive group-containing monomer as a monomer unit constituting the polymer in an upper limit of 40% by mass or less, particularly 30% by mass or less. It is preferably contained, more preferably 25% by mass or less. When the (meth)acrylic acid ester polymer (A) contains the reactive group-containing monomer in the above amount as a monomer unit, a good crosslinked structure is formed in the obtained pressure-sensitive adhesive, and desired cohesive strength is obtained. In addition, the dispersibility of the white colorant (C) in the adhesive tends to be good, and the obtained adhesive has good reproducibility and uniformity of the optical properties described above, and the color difference ΔE* becomes easier to meet.

It is also preferable that the (meth)acrylic acid ester polymer (A) does not contain a carboxy group-containing monomer as a monomer unit constituting the polymer. Since the carboxyl group is an acid component, the absence of the carboxyl group-containing monomer prevents the adhesive from being applied to objects to which the acid is attached, such as transparent conductive films such as tin-doped indium oxide (ITO), metal films, and the like. Even if it exists, it is possible to suppress those problems (corrosion, resistance value change, etc.) caused by the acid. However, it is permissible to contain a predetermined amount of the carboxy group-containing monomer to the extent that such problems do not occur. Specifically, the (meth)acrylic acid ester polymer (A) contains, as a monomer unit, a carboxy group-containing monomer of 0.1% by mass or less, preferably 0.01% by mass or less, more preferably 0.001% by mass. It is allowed to be contained in an amount of mass % or less.

The (meth)acrylic acid ester polymer (A) preferably contains a (meth)acrylic acid alkyl ester as a monomer unit constituting the polymer. Thereby, favorable adhesiveness can be expressed. Alkyl groups may be straight or branched.

As the (meth)acrylic acid alkyl ester, a (meth)acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms is preferable from the viewpoint of adhesiveness. Examples of (meth)acrylic acid alkyl esters having an alkyl group of 1 to 20 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-(meth)acrylate, Butyl, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-decyl (meth)acrylate, (meth)acrylic acid Examples include n-dodecyl, myristyl (meth)acrylate, palmityl (meth)acrylate, and stearyl (meth)acrylate. Among them, from the viewpoint of further improving the adhesiveness, (meth) acrylic acid esters having an alkyl group having 1 to 8 carbon atoms are preferable, and methyl (meth) acrylate, n-butyl (meth) acrylate or (meth) acrylic 2-Ethylhexyl acid is particularly preferred, more preferably methyl methacrylate, n-butyl acrylate or 2-ethylhexyl acrylate. In addition, these may be used independently and may be used in combination of 2 or more type.

The (meth)acrylic acid ester polymer (A) preferably contains 40% by mass or more, particularly 50% by mass or more, of (meth)acrylic acid alkyl ester as monomer units constituting the polymer. It is preferably contained in an amount of 60% by mass or more. When the lower limit of the content of the (meth)acrylic acid alkyl ester is the above, the (meth)acrylic acid ester polymer (A) can exhibit suitable adhesiveness. In addition, the dispersibility of the white colorant (C) in the adhesive tends to be good, and the (meth)acrylic acid ester polymer (A) is suppressed from impairing the desired adhesiveness. As a result, the pressure-sensitive adhesive obtained can exhibit suitable adhesiveness, and the reproducibility and uniformity of the optical properties described above can be improved, making it easier to satisfy the color difference ΔE* described above. In addition, the (meth)acrylic acid ester polymer (A) preferably contains 99% by mass or less, more preferably 95% by mass or less, of (meth)acrylic acid alkyl ester as monomer units constituting the polymer. is more preferable, particularly preferably 90% by mass or less, and more preferably 85% by mass or less. When the upper limit of the content of the (meth)acrylic acid alkyl ester is the above, a suitable amount of another monomer component such as a reactive functional group-containing monomer is introduced into the (meth)acrylic acid ester polymer (A). be able to.

The (meth)acrylic acid ester polymer (A) preferably contains a monomer having an alicyclic structure in its molecule (alicyclic structure-containing monomer) as a monomer unit constituting the polymer. Since the alicyclic structure-containing monomer is bulky, it is presumed that the presence of this in the polymer widens the distance between the polymers, and the obtained pressure-sensitive adhesive can be made excellent in flexibility. . As a result, the pressure-sensitive adhesive becomes excellent in step followability.

The carbon ring of the alicyclic structure in the alicyclic structure-containing monomer may have a saturated structure or may partially have an unsaturated bond. The alicyclic structure may be a monocyclic alicyclic structure or a polycyclic alicyclic structure such as bicyclic or tricyclic. From the viewpoint of optimizing the distance between the resulting (meth)acrylic acid ester polymer (A) and imparting higher stress relaxation properties to the pressure-sensitive adhesive, the alicyclic structure is a polycyclic alicyclic structure ( polycyclic structure). Furthermore, in consideration of compatibility between the (meth)acrylic acid ester polymer (A) and other components, the polycyclic structure is particularly preferably bicyclic to tetracyclic. In addition, from the viewpoint of imparting stress relaxation properties as described above, the number of carbon atoms in the alicyclic structure (the number of all carbon atoms in the portion forming the ring, and when a plurality of rings are independently present , which means the total number of carbon atoms) is usually preferably 5 or more, particularly preferably 7 or more. On the other hand, although the upper limit of the number of carbon atoms in the alicyclic structure is not particularly limited, it is preferably 15 or less, 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, (meth)acrylic Examples include dicyclopentenyl acid, dicyclopentenyloxyethyl (meth)acrylate, and among them, dicyclopentenyl (meth)acrylate (the number of carbon atoms in the alicyclic structure: 10), adamantyl (meth)acrylate (the number of carbon atoms in the alicyclic structure: 10) or isobornyl (meth)acrylate (the number of carbon atoms in the alicyclic structure: 7) is preferred, and isobornyl (meth)acrylate is particularly preferred. and isobornyl acrylate are preferred. These may be used individually by 1 type, and may be used in combination of 2 or more type.

When the (meth)acrylic acid ester polymer (A) contains an alicyclic structure-containing monomer as a monomer unit constituting the polymer, it preferably contains 1% by mass or more of the alicyclic structure-containing monomer. In particular, it is preferably contained in an amount of 4% by mass or more, more preferably 8% by mass or more. In addition, the (meth)acrylic acid ester polymer (A) preferably contains 30% by mass or less, particularly 22% by mass or less, of an alicyclic structure-containing monomer as a monomer unit constituting the polymer. is preferred, and it is more preferred to contain 14% by mass or less. When the content of the alicyclic structure-containing monomer is within the above range, the pressure-sensitive adhesive to be obtained has more excellent conformability to irregularities and more excellent adhesion to plastics.

The (meth)acrylic acid ester polymer (A) also preferably contains a nitrogen atom-containing monomer as a monomer unit constituting the polymer. Predetermined polarity is imparted to the pressure-sensitive adhesive by allowing nitrogen atom-containing monomers to be present in the polymer as structural units, and excellent affinity is obtained even for adherends having a certain degree of polarity, such as glass. can be As the nitrogen atom-containing monomer, a monomer having a nitrogen-containing heterocyclic ring is preferable from the viewpoint of imparting appropriate rigidity to the (meth)acrylic acid ester polymer (A). In addition, from the viewpoint of increasing the degree of freedom of the portion derived from the nitrogen atom-containing monomer in the higher-order structure of the pressure-sensitive adhesive, the nitrogen atom-containing monomer forms the (meth)acrylic acid ester polymer (A). preferably contains no reactive unsaturated double bond groups other than the one polymerizable group used in the polymerization of .

Examples of monomers having a nitrogen-containing heterocyclic ring include N-(meth)acryloylmorpholine, N-vinyl-2-pyrrolidone, N-(meth)acryloylpyrrolidone, N-(meth)acryloylpiperidine, N-(meth)acryloyl pyrrolidine, N-(meth)acryloylaziridine, aziridinylethyl (meth)acrylate, 2-vinylpyridine, 4-vinylpyridine, 2-vinylpyrazine, 1-vinylimidazole, N-vinylcarbazole, N-vinylphthalimide, etc. Among them, N-(meth)acryloylmorpholine, which exhibits superior adhesive strength, is preferred, and N-acryloylmorpholine is particularly preferred. These may be used individually by 1 type, and may be used in combination of 2 or more type.

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

The (meth)acrylic acid ester polymer (A) may optionally contain other monomers as monomer units constituting the polymer. As other monomers, monomers containing no reactive functional groups are preferred so as not to inhibit the above-described effects of the reactive functional group-containing monomers. Examples of such monomers include alkoxyalkyl (meth)acrylates such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate, vinyl acetate, and styrene. These may be used alone or in combination of two or more.

The (meth)acrylate polymer (A) is preferably a linear polymer. By being a straight-chain polymer, entanglement of molecular chains is likely to occur, and an improvement in cohesive strength can be expected. Therefore, the resulting pressure-sensitive adhesive tends to exhibit a suitable gel fraction, adhesive strength, and the like, and tends to be excellent in step followability under high-temperature and high-humidity conditions.

Moreover, the (meth)acrylate polymer (A) is preferably a solution polymer obtained by a solution polymerization method. Since it is a solution polymer, it becomes easy to obtain a polymer with a high molecular weight, and an improvement in cohesion can be expected. Therefore, the resulting pressure-sensitive adhesive tends to exhibit a suitable gel fraction, adhesive strength, and the like, and tends to be excellent in step followability under high-temperature and high-humidity conditions.

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

The weight-average molecular weight of the (meth)acrylate polymer (A) is preferably 200,000 or more, particularly preferably 300,000 or more, further preferably 400,000 or more as a lower limit. When the lower limit of the weight average molecular weight of the (meth)acrylic acid ester polymer (A) is the above, the gel fraction and storage elastic modulus of the obtained pressure-sensitive adhesive tend to be suitable, and The step followability at the In addition, the white colorant (C) tends to have good dispersibility in the pressure-sensitive adhesive. It becomes easier to satisfy the color difference ΔE*.

The upper limit of the weight average molecular weight of the (meth)acrylic acid ester polymer (A) is preferably 2,000,000 or less, more preferably 1,500,000 or less, and particularly preferably 1,000,000 or less. , and more preferably 800,000 or less. When the upper limit of the weight average molecular weight of the (meth)acrylic acid ester polymer (A) is the above, the gel fraction and storage elastic modulus of the obtained pressure-sensitive adhesive tend to be suitable, and the initial step conformability is better. In addition, the weight average molecular weight in this specification is the value of standard polystyrene conversion measured by the gel permeation chromatography (GPC) method.

In addition, in the adhesive composition P, the (meth)acrylic acid ester polymer (A) may be used alone or in combination of two or more.

(1-2) Crosslinking agent (B)
The cross-linking agent (B) cross-links the (meth)acrylic acid ester polymer (A) by heating the pressure-sensitive adhesive composition P, making it possible to satisfactorily form a three-dimensional network structure. As a result, the cohesive force of the resulting pressure-sensitive adhesive is improved, and the step conformability under high-temperature and high-humidity conditions is excellent.

The cross-linking agent (B) may be one that reacts with the reactive groups of the (meth)acrylic acid ester polymer (A). Examples include isocyanate cross-linking agents, epoxy cross-linking agents, and amine cross-linking agents. , melamine cross-linking agent, aziridine cross-linking agent, hydrazine cross-linking agent, aldehyde cross-linking agent, oxazoline cross-linking agent, metal alkoxide cross-linking agent, metal chelate cross-linking agent, metal salt cross-linking agent, ammonium salt cross-linking agent, etc. is mentioned. Among the above, it is preferable to use an isocyanate-based cross-linking agent that has excellent reactivity with the reactive groups of the (meth)acrylic acid ester polymer (A). In addition, a crosslinking agent (B) can be used individually by 1 type or in combination of 2 or more types.

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

The content of the cross-linking agent (B) in the adhesive composition P is preferably 0.01 parts by mass or more, particularly 0.01 part by mass, based on 100 parts by mass of the (meth)acrylic acid ester polymer (A). 05 parts by mass or more, and more preferably 0.1 parts by mass or more. 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 parts by mass or less. is preferred. When the content of the cross-linking agent (B) is within the above range, the obtained pressure-sensitive adhesive exhibits good cohesive strength, and tends to have suitable values such as gel fraction and adhesive strength, and can be used under high-temperature and high-humidity conditions. It becomes excellent due to the ability to follow a step below.

(1-3) White colorant (C)
The white colorant (C) is the white colorant described above. Specific types and contents are as described above.

(1-4) Active energy ray-curable component (D)
In the adhesive obtained by curing the adhesive obtained by cross-linking the adhesive composition P with an active energy ray, the active energy ray-curable component (D) is polymerized with each other, and the polymerized active energy ray-curable component (D) is It is presumed to be entwined with the crosslinked structure (three-dimensional network structure) of the (meth)acrylic acid ester polymer (A). A pressure-sensitive adhesive having such a high-order structure is particularly excellent in step conformability under high-temperature and high-humidity conditions.

The active energy ray-curable component (D) is not particularly limited as long as it is a component that cures by irradiation with an active energy ray and provides the above effects, and may be any of monomers, oligomers or polymers. may be a mixture of Among them, polyfunctional acrylate-based monomers, which are superior in step conformability under high-temperature and high-humidity conditions, are preferred.

Examples of polyfunctional acrylate monomers include 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, and polyethylene glycol di(meth)acrylate. , neopentyl glycol adipate di(meth)acrylate, neopentyl glycol hydroxypivalate di(meth)acrylate, dicyclopentanyl di(meth)acrylate, tricyclodecanedimethanol (meth)acrylate, caprolactone-modified dicyclopentenyl di( meth)acrylate, ethylene oxide-modified phosphoric acid di(meth)acrylate, di(acryloxyethyl)isocyanurate, allylated cyclohexyl di(meth)acrylate, ethoxylated bisphenol A diacrylate, 9,9-bis[4-(2- Bifunctional type such as acryloyloxyethoxy)phenyl]fluorene; 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(acryloxyethyl) isocyanurate, ε-caprolactone-modified tris-(2-(meth)acryloxyethyl) isocyanurate; diglycerin tetra ( Tetrafunctional type such as meth)acrylate and pentaerythritol tetra(meth)acrylate; Pentafunctional type such as propionic acid-modified dipentaerythritol penta(meth)acrylate; Dipentaerythritol hexa(meth)acrylate, caprolactone-modified dipentaerythritol hexa( Hexafunctional type such as meth)acrylate and the like can be mentioned. These may be used individually by 1 type, and may be used in combination of 2 or more type. From the viewpoint of compatibility with the (meth)acrylic acid ester polymer (A), the polyfunctional acrylate monomer preferably has a molecular weight of less than 1,000.

When the adhesive composition P contains the active energy ray-curable component (D), the content of the active energy ray-curable component (D) in the adhesive composition P is the (meth) acrylic ester polymer ( A) With respect to 100 parts by mass, the lower limit is preferably 1 part by mass or more, particularly preferably 3 parts by mass or more, and further preferably 4 parts by mass or more. On the other hand, the upper limit of the content is preferably 30 parts by mass or less, particularly preferably 20 parts by mass or less, and 14 parts by mass or less, from the viewpoint of the adhesive strength of the adhesive after curing with active energy rays. It is more preferable that the content is 9 parts by mass or less from the viewpoint of easily exhibiting a higher adhesive strength. When the content of the active energy ray-curable component (D) is within the above range, the adhesive after active energy ray curing tends to have suitable values such as gel fraction and adhesive strength, and can be used under high temperature and high humidity conditions. It becomes excellent due to the ability to follow a step below.

(1-5) Photopolymerization initiator (E)
When ultraviolet rays are used as 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 way, the active energy ray-curable component (D) can be efficiently polymerized, and the polymerization curing time and the irradiation dose of the active energy ray can be reduced. can.

Examples of such photoinitiators (E) include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy -2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexylphenylketone, 2-methyl-1-[4- (methylthio)phenyl]-2-morpholino-propan-1-one, 4-(2-hydroxyethoxy)phenyl-2-(hydroxy-2-propyl)ketone, benzophenone, p-phenylbenzophenone, 4,4'-diethylamino Benzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tertiary-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2 , 4-diethylthioxanthone, benzyl dimethyl ketal, acetophenone dimethyl ketal, 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 may be used alone or in combination of two or more.

When the adhesive composition P contains a photopolymerization initiator (E), the content of the photopolymerization initiator (E) in the adhesive composition P is 100 parts by mass of the active energy ray-curable component (D). On the other hand, the lower limit is preferably 0.1 parts by mass or more, particularly preferably 1 part by mass or more, and more preferably 5 parts by mass or more. Also, 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.

(1-6) Various Additives The adhesive composition P may optionally contain various additives commonly used in acrylic adhesives, such as silane coupling agents, rust inhibitors, ultraviolet absorbers, and antistatic agents. , tackifiers, antioxidants, light stabilizers, softeners, refractive index modifiers and the like can be added. It should be noted that a polymerization solvent and a dilution solvent, which will be described later, are not included in the additives constituting the adhesive composition P.

The adhesive composition P preferably contains a silane coupling agent among the above. As a result, even if the adherend is a plastic plate or a glass member, the adhesion to the adherend is improved, and the step followability under high-temperature and high-humidity conditions is improved. .

As the silane coupling agent, an organosilicon compound having at least one alkoxysilyl group in the molecule, having good compatibility with the (meth)acrylic acid ester polymer (A), and having optical transparency. preferable.

Such silane coupling agents include, for example, vinyltrimethoxysilane, vinyltriethoxysilane, methacryloxypropyltrimethoxysilane and like silicon compounds containing polymerizable unsaturated groups, 3-glycidoxypropyltrimethoxysilane, 2-( Silicon compounds having an epoxy structure such as 3,4-epoxycyclohexyl)ethyltrimethoxysilane, mercapto group-containing silicon compounds such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, and 3-mercaptopropyldimethoxymethylsilane , 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane and other amino group-containing silicon compounds, 3-chloropropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, or at least one of these, and an alkyl group-containing silicon compound such as methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane, etc. and condensates of. These may be used individually by 1 type, and may be used in combination of 2 or more type.

The content of the silane coupling agent in the adhesive composition P is preferably 0.01 parts by mass or more, particularly 0.05 parts by mass, relative to 100 parts by mass of the (meth)acrylic acid ester polymer (A). It is preferably at least 0.1 part by mass, more preferably at least 0.1 part by mass. Also, the content is preferably 1 part by mass or less, particularly preferably 0.5 parts by mass or less, and further preferably 0.3 parts by mass or less.

(2) Preparation of adhesive composition The adhesive composition P is produced by producing a (meth) acrylic acid ester polymer (A), the obtained (meth) acrylic acid ester polymer (A), and a cross-linking agent ( It can be produced by mixing B) with a white colorant (C), and optionally adding an active energy ray-curable component (D), a photopolymerization initiator (E), an additive, and the like.

The (meth)acrylic acid ester polymer (A) can be produced by polymerizing a mixture of monomers constituting the polymer by a conventional radical polymerization method. Polymerization of the (meth)acrylic acid ester polymer (A) is preferably carried out by a solution polymerization method, optionally using a polymerization initiator. However, the present invention is not limited to this, and may be polymerized 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 in combination.

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

Examples of organic peroxides include benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropylperoxydicarbonate, di-n-propylperoxydicarbonate, di(2-ethoxyethyl)peroxy dicarbonate, t-butylperoxyneodecanoate, t-butylperoxybivalate, (3,5,5-trimethylhexanoyl)peroxide, dipropionylperoxide, diacetylperoxide and the like.

The weight average molecular weight of the resulting polymer can be adjusted by adding a chain transfer agent such as 2-mercaptoethanol in the polymerization step.

After the (meth)acrylic acid ester polymer (A) is obtained, the solution of the (meth)acrylic acid ester polymer (A) is added with a cross-linking agent (B), a white colorant (C), and optionally a diluent solvent, An active energy ray-curable component (D), a photopolymerization initiator (E), additives and the like are added and thoroughly mixed to obtain a solvent-diluted adhesive composition P (coating solution). In any of the above components, if a solid one is used, or if precipitation occurs when mixed with other components in an undiluted state, the component is added alone in advance to a dilution solvent. It may be dissolved or diluted prior to mixing with other ingredients.

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 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 are used.

The concentration/viscosity of the coating solution thus prepared is not particularly limited as long as it is within a range that allows coating, and can be appropriately selected according to the situation. For example, the concentration of the adhesive composition P is diluted to 10 to 60% by mass. When obtaining the coating solution, the addition of a diluent solvent or the like is not a necessary condition, and the diluent solvent may not be added as long as the viscosity of the adhesive composition P allows coating. In this case, the adhesive composition P becomes a coating solution in which the polymerization solvent for the (meth)acrylic acid ester polymer (A) is used as the diluting solvent.

(3) Formation of Adhesive Layer The adhesive layer 11 in the present embodiment is preferably made of an adhesive obtained by cross-linking (the coating layer of) the adhesive composition P. Crosslinking of the adhesive composition P can usually be performed by heat treatment. This heat treatment can also serve as a drying treatment for volatilizing the diluent solvent from the coating layer of the adhesive composition P applied to the desired object.

The heating temperature of the heat treatment is preferably 50 to 150°C, particularly preferably 70 to 120°C. The heating time is preferably 10 seconds to 10 minutes, more preferably 50 seconds to 2 minutes.

After the heat treatment, if necessary, a curing period of about 1 to 2 weeks may be provided at room temperature (eg, 23° C., 50% RH). If the curing period is required, the adhesive is formed after the curing period has elapsed, and if the curing period is not required, the adhesive is formed after the heat treatment is completed.

By the above heat treatment (and curing), the (meth)acrylate polymer (A) is sufficiently crosslinked via the crosslinking agent (B). The pressure-sensitive adhesive thus obtained easily satisfies the desired values of gel fraction, storage modulus, adhesive strength, etc., and is excellent in step followability under high-temperature and high-humidity conditions.

(4) Physical properties of the adhesive (4-1) Gel fraction The gel fraction of the adhesive constituting the adhesive layer 11 in the present embodiment is preferably 20% or more as a lower limit, and 30% or more. It is more preferably 40% or more, particularly preferably 48% or more, and most preferably 55% or more. When the lower limit of the gel fraction of the pressure-sensitive adhesive is above, the pressure-sensitive adhesive has a high cohesive force, and the step followability under high-temperature and high-humidity conditions becomes more excellent. In addition, the upper limit of the gel fraction of the adhesive according to the present embodiment is preferably 99% or less, more preferably 90% or less, particularly preferably 80% or less, and further preferably 74%. % or less. When the upper limit of the gel fraction of the pressure-sensitive adhesive is above, the pressure-sensitive adhesive does not become too hard, and the initial conformability to unevenness and the conformability to unevenness under high-temperature and high-humidity conditions are both excellent. In addition, good adhesive strength is exhibited, and the adhesiveness to the adherend becomes more excellent. Here, the method for measuring the gel fraction of the pressure-sensitive adhesive is as shown in the test examples described later.

In the case of an active energy ray-curable adhesive, the lower limit of the gel fraction of the adhesive after active energy ray curing is preferably 30% or more, more preferably 40% or more, and particularly 55%. It is preferably 65% or more, more preferably 65% or more. The upper limit of the gel fraction is preferably 99% or less, more preferably 90% or less, particularly preferably 85% or less, and further preferably 80% or less. . When the gel fraction of the adhesive after active energy ray curing is within the above range, the conformability to unevenness under high-temperature and high-humidity conditions becomes more excellent. In addition, good adhesive strength is exhibited, and the adhesiveness to the adherend becomes more excellent.

(4-2) Storage Elastic Modulus The storage elastic modulus at 23° C. of the adhesive constituting the adhesive layer 11 in the present embodiment is preferably 0.001 MPa or more as a lower limit, particularly 0.01 MPa or more. is preferably 0.04 MPa or more, and most preferably 0.07 MPa or more. By setting the lower limit of the storage elastic modulus to the above range, it becomes excellent in step followability under high-temperature and high-humidity conditions. The upper limit of the storage elastic modulus is preferably 3 MPa or less, particularly preferably 1 MPa or less, further preferably 0.5 MPa or less, and most preferably 0.2 MPa or less. . By setting the upper limit of the storage elastic modulus to the above range, the initial conformability to unevenness is excellent. The storage elastic modulus in this specification is a value measured by a torsional shear method at a measurement frequency of 1 Hz in accordance with JIS K7244-6. Specifically, it is as shown in the test examples described later.

In the case of an active energy ray-curable adhesive, the storage elastic modulus at 23° C. of the adhesive after active energy ray curing is preferably 0.10 MPa or more as a lower limit, more preferably 0.15 MPa or more. It is preferably 0.20 MPa or more, more preferably 0.25 MPa or more. By setting the lower limit of the storage elastic modulus to the above range, the step followability under high-temperature and high-humidity conditions becomes more excellent. The upper limit of the storage elastic modulus is preferably 5 MPa or less, particularly preferably 1 MPa or less, and further preferably 0.5 MPa or less. By setting the upper limit of the storage elastic modulus to the above range, the adhesiveness is excellent.

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

Examples of the release sheets 12a and 12b include polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polyethylene naphthalate film, and polybutylene. Terephthalate film, polyurethane film, ethylene vinyl acetate film, ionomer resin film, ethylene/(meth)acrylic acid copolymer film, ethylene/(meth)acrylic acid ester copolymer film, polystyrene film, polycarbonate film, polyimide film, fluorine A resin film or the like is used. Crosslinked films of these are also used. Furthermore, a laminated film of these may be used.

The release surfaces of the release sheets 12a and 12b (especially the surfaces in contact with the pressure-sensitive adhesive layer 11) are preferably subjected to a release treatment. Examples of release agents used in 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, it is preferable that one of the release sheets is a heavy release type release sheet with a large release force, and the other release sheet is a light release type release sheet with a small release force.

Although the thickness of the release sheets 12a and 12b is not particularly limited, it is usually about 20 to 150 μm.

2. Physical properties (1) Adhesive strength The adhesive strength of the adhesive sheet 1 according to the present embodiment to soda lime glass is preferably 1 N/25 mm or more as a lower limit, more preferably 5 N/25 mm or more, and 10 N/25 mm. It is particularly preferably 15 N/25 mm or more, and more preferably 15 N/25 mm or more. When the lower limit of the adhesive strength is above, the step followability under high temperature and high humidity conditions becomes more excellent. The upper limit of the adhesive strength is preferably 70 N/25 mm or less, more preferably 60 N/25 mm or less, and particularly preferably 50 N/25 mm or less. When the upper limit of the adhesive strength is above, good reworkability is obtained, and when a lamination error occurs, it becomes possible to reuse display body constituent members, especially expensive display body constituent members.

When the adhesive constituting the adhesive layer 11 is an active energy ray-curable adhesive, the adhesive strength of the adhesive sheet 1 according to the present embodiment to soda lime glass after being irradiated with an active energy ray is 5 N/25 mm as a lower limit. It is preferably 10 N/25 mm or more, particularly preferably 20 N/25 mm or more, further preferably 25 N/25 mm or more. When the lower limit of the adhesive strength is above, the step followability under high temperature and high humidity conditions becomes more excellent. The upper limit of the adhesive strength is preferably 70 N/25 mm or less, more preferably 60 N/25 mm or less, and particularly preferably 50 N/25 mm or less. When the upper limit of the adhesive strength is above, good reworkability can be obtained, and in the event of a lamination error, it becomes possible to reuse display body constituent members, especially expensive display body constituent members.

Here, the adhesive strength in this specification basically refers to the adhesive strength measured by the 180 degree peeling method according to JIS Z0237: 2009, but the measurement sample has a width of 25 mm and a length of 100 mm. It is attached to an adherend, pressurized at 0.5 MPa and 50° C. for 20 minutes, then left under normal pressure, 23° C. and 50% RH for 24 hours, and then measured at a peel rate of 300 mm/min. shall be The adhesive strength after irradiation with active energy rays is the adhesive strength of the adhesive layer cured by irradiation with active energy rays after sticking to an adherend.

(2) Level difference followability With regard to level difference followability under high-temperature and high-humidity conditions, the pressure-sensitive adhesive layer 11 preferably has a level difference followability (%) represented by the following formula of 5% or more, and 10% or more. It is more preferably 20% or more, particularly preferably 30% or more, and most preferably 40% or more. As a result, it can be said that the step followability under high-temperature and high-humidity conditions is excellent, and in that case, it can be said that the step followability at the initial stage (at the time of lamination) is also excellent. Although the upper limit of the step follow-up rate is not particularly limited, it is usually preferably 80% or less, and particularly preferably 70% or less.
Level difference follow-up rate (%) = {(height of level difference maintained in a buried state without air bubbles, floating, peeling, etc. after a predetermined durability test (μm))/(thickness of adhesive layer)}×100
The test method for the step followability rate is as shown in the test examples described later. In addition, for the active energy ray-curable adhesive layer, it is the step follow-up rate of the adhesive layer cured by irradiating the active energy ray after sticking to the adherend.

3. Manufacture of Adhesive Sheet As an example of manufacturing the adhesive sheet 1, the coating solution of the adhesive composition P is applied to the release surface of one of the release sheets 12a (or 12b) and heat-treated to form the adhesive composition. After thermally cross-linking P to form a coating layer, the release surface of the other release sheet 12b (or 12a) is superposed on the coating layer. If a curing period is required, a curing period is provided, and if the curing period is not required, the coating layer becomes the adhesive layer 11 as it is. As a result, the pressure-sensitive adhesive sheet 1 is obtained. The conditions for heat treatment and curing are as described above.

As another production example of the adhesive sheet 1, the coating solution of the adhesive composition P is applied to the release surface of one release sheet 12a, heat treatment is performed to thermally crosslink the adhesive composition P, and the coating is performed. A layer is formed to obtain 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. to obtain a release sheet 12b. Then, the release sheet 12a with the coating layer and the release sheet 12b with the coating layer are pasted together so that both coating layers are in contact with each other. Here, a plurality of release sheets with coating layers may be prepared, and a desired number of the coating layers may be pasted together. If a curing period is required, the curing period is set, and if the curing period is not required, the laminated coating layer becomes the adhesive layer 11 as it is. As a result, the pressure-sensitive adhesive sheet 1 is obtained. According to this production example, even when the pressure-sensitive adhesive layer 11 is thick, it is possible to produce stably.

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

[Display body]
Examples of the type of the display according to the present embodiment include televisions, monitors for personal computers, monitors for various devices, digital signage, smartphones, tablets, and the like. These displays are sometimes required to harmonize their appearance with white peripheral members such as white frames, white walls, and white printed parts. However, the display body according to the present invention is not limited to these.

As shown in FIG. 2, the display body 2 according to the present embodiment includes a first display body constituting member 21 (one display body constituting member) and a second display body constituting member 22 (another display body constituting member). ) and the pressure-sensitive adhesive layer 11 positioned therebetween for adhering the first display body-constituting member 21 and the second display body-constituting member 22 to each other.

At least one of the first display body-constituting member 21 and the second display body-constituting member 22 may have a step on the side bonded with the pressure-sensitive adhesive layer 11 . In this embodiment shown in FIG. 2, the first display member constituting member 21 has a step such as the printed layer 3 on the surface on the pressure-sensitive adhesive layer 11 side.

The adhesive layer 11 in the display body 2 is formed from the adhesive layer 11 of the adhesive sheet 1 described above. Specifically, the adhesive layer 11 in the display 2 may be the adhesive layer 11 itself of the adhesive sheet 1, or may be the adhesive layer 11 cured with active energy rays.

Examples of the display 2 include a liquid crystal display (LCD), a light emitting diode (LED) display, an organic electroluminescence (organic EL) display, electronic paper, and the like, and may be a touch panel. Moreover, it may be a member that constitutes a part of them.

The first display member constituting member 21 is preferably a protective panel made of a glass plate, a plastic plate or the like, or a laminated body including them. In this case, the printed layer 3 is generally formed in a frame shape on the adhesive layer 11 side of the first display member constituting member 21 .

Examples of the glass plate include, but are not limited to, 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 etc. are mentioned. Although the thickness of the glass plate is not particularly limited, it is usually 0.1 to 5 mm, preferably 0.2 to 2 mm.

Examples of the plastic plate include, but are not limited to, an acrylic plate, a polycarbonate plate, and the like. Although the thickness of the plastic plate is not particularly limited, it is usually 0.2 to 5 mm, preferably 0.4 to 3 mm.

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 or both sides of the glass plate or the plastic plate. may be laminated. Moreover, the transparent conductive film and the metal layer may be patterned.

The second display body constituent member 22 is an optical member to be attached to the first display body constituent member 21, a display body module (for example, a liquid crystal module, a light emitting diode (LED) module, an organic electroluminescence (organic EL) module). etc.), or a laminate including a display module.

Examples of the optical member include anti-scattering films, polarizing films, retardation films, viewing angle compensation films, brightness enhancement films, contrast enhancement films, liquid crystal polymer films, diffusion films, transflective films, transparent conductive films, and films. A sensor etc. are mentioned. Examples of the anti-scattering film include a hard coat film in which a hard coat layer is formed on one side of a base film.

The color of the printed layer 3 in this embodiment is preferably white. The material constituting the printing layer 3 is not particularly limited, and known materials for printing are used. The lower limit of the thickness of the printing 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. preferable. When the lower limit value is above the above, it is possible to sufficiently secure the concealability such as making the electric wiring invisible from the viewer side. Also, the upper limit is preferably 200 μm or less, more preferably 100 μm or less, and particularly preferably 30 μm or less. When the upper limit value is equal to or less than the above, it is possible to prevent the pressure-sensitive adhesive layer 11 from deteriorating in the followability of the pressure-sensitive adhesive layer 11 to the printed layer 3 .

In order to manufacture the display body 2, as an example, one release sheet 12a of the adhesive sheet 1 is peeled off, and the exposed adhesive layer 11 of the adhesive sheet 1 is replaced with the printed layer of the first display body constituent member 21. 3 is pasted on the side on which 3 is present.

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

When the adhesive layer 11 is active energy ray-curable, after bonding the first display body constituent member 21 and the second display body constituent member 22 via the adhesive layer 11 as described above, The adhesive layer 11 is irradiated with active energy rays. As a result, the energy ray-curable component (D) in the adhesive layer 11 is polymerized and the adhesive layer 11 is cured. Irradiation of energy rays to the pressure-sensitive adhesive layer 11 is usually carried out through either the first display member constituting member 21 or the second display member constituting member 22, preferably through the first display member as a protective panel. It is carried out over the constituent member 21 .

The active energy ray refers to an electromagnetic wave or a charged particle beam that has energy quanta, and specifically includes ultraviolet rays, electron beams, and the like. Among active energy rays, ultraviolet rays are particularly preferable because they are easy to handle.

Ultraviolet irradiation can ^be performed by a high-pressure mercury lamp, a fusion H lamp, a xenon lamp, or ^the like. is preferred. The amount of light is preferably 50 to 10000 mJ/cm ² , more preferably 200 to 7000 mJ/cm ² and particularly preferably 500 to 3000 mJ/cm ² . On the other hand, electron beam irradiation can be performed by an electron beam accelerator or the like, and the electron beam irradiation dose is preferably about 10 to 1000 krad.

Here, as shown in FIG. 3, the display body 2 according to this embodiment may have a white frame material 4 on the periphery of the display body 2 .

The physical properties of the pressure-sensitive adhesive layer 11 described above give the display member 2 a sense of unity with the white frame member 4, and have excellent appearance harmony. Further, the display body 2 ensures visibility as a display body.

Furthermore, in the display body 2, when the pressure-sensitive adhesive layer 11 is formed from the pressure-sensitive adhesive composition P, the pressure-sensitive adhesive layer 11 has excellent step conformability under high-temperature and high-humidity conditions. However, even when placed under high-temperature and high-humidity conditions (eg, 85° C., 85% RH), the occurrence of air bubbles, floating, peeling, etc. near the step is suppressed.

The embodiments described above are described to facilitate understanding of the present invention, and are not described to limit the present invention. Therefore, each element disclosed in the above embodiment is meant to include all design changes and equivalents that fall within the technical scope of the present invention.

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

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]
1. Preparation of (meth)acrylic acid ester polymer 70 parts by mass of 2-ethylhexyl acrylate, 15 parts by mass of methyl methacrylate, and 15 parts by mass of 2-hydroxyethyl acrylate are copolymerized by a solution polymerization method to obtain a (meth)acrylic ester polymer. An acid ester polymer (A) was prepared. When the molecular weight of this (meth)acrylic acid ester polymer (A) was measured by the method described later, it was found to have a weight average molecular weight (Mw) of 700,000.

2. Preparation of adhesive composition 100 parts by mass of the (meth)acrylic acid ester polymer (A) obtained in the above step 1 (solid content conversion value; the same applies hereinafter), and a trimethylolpropane-modified trimethylolpropane-modified trimethylolpropane 0.2 parts by mass of diisocyanate (manufactured by Toyochem, product name "BHS8515"), 1.0 parts by mass of a titanium oxide colorant as a white colorant (C), and 3-glycide as a silane coupling agent 0.2 parts by mass of oxypropyltrimethoxysilane was mixed, sufficiently stirred, and diluted with methyl ethyl ketone to obtain a coating solution of the adhesive composition.

Here, Table 1 shows each formulation (solid content conversion value) of the adhesive composition when the (meth)acrylic acid ester polymer (A) is 100 parts by mass (solid content conversion value). Details of abbreviations and the like in Table 1 are as follows.
[(Meth) acrylic ester polymer (A)]
2EHA: 2-ethylhexyl acrylate MMA: methyl methacrylate HEA: 2-hydroxyethyl acrylate IBXA: isobornyl acrylate ACMO: N-acryloylmorpholine BA: n-butyl acrylate AA: acrylic acid
[Crosslinking agent (B)]
TDI: trimethylolpropane-modified tolylene diisocyanate (manufactured by Toyochem, product name “BHS8515”)
XDI: trimethylolpropane-modified xylylene diisocyanate (manufactured by Soken Chemical Co., Ltd., product name “TD-75”)

The composition of the titanium oxide colorant as the white colorant (C) was 91.2% by mass of titanium oxide, 0.8% by mass of zinc oxide, and 8% by mass of silica. The titanium oxide colorant had a mode diameter of 420 nm and a median diameter of 420 nm. The particle size was measured by a dynamic light scattering method (MicrotracBEL, device name: Nanotrac Wave).

3. Production of adhesive sheet The coating solution of the adhesive composition obtained in the above step 2 is applied to a heavy release type release sheet (manufactured by Lintec Co., Ltd., product name "SP-PET752150") in which one side of a polyethylene terephthalate film is release treated with a silicone release agent. ”) was coated with a knife coater. Then, the coating layer was heat-treated at 90° C. for 1 minute to form a coating layer (thickness: 50 μm), thereby producing a heavy release release sheet with a coating layer.

On the other hand, the coating solution of the adhesive composition obtained in the above step 2 is applied to a light release type release sheet (manufactured by Lintec, product name "SP-PET382120") obtained by releasing one side of a polyethylene terephthalate film with a silicone release agent. was applied to the release-treated surface of the sheet with a knife coater. Then, the coating layer was heat-treated at 90° C. for 1 minute to form a coating layer (thickness: 50 μm), thereby producing a light release release sheet with a coating layer.

The coating layer side surface of the heavy release release sheet with the coating layer obtained above and the coating layer side surface of the light release release sheet with the coating layer obtained above are laminated, and the thickness A laminate was obtained in which a coating layer of 100 μm was sandwiched between the heavy release type release sheet and the light release type release sheet.

After that, the laminate was cured for 7 days under the conditions of 23° C. and 50% RH to obtain an adhesive composition consisting of a heavy release release sheet/adhesive layer (thickness: 100 μm)/light release release sheet. manufactured the sheet.

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

[Examples 2 to 10, Comparative Examples 1 to 2]
Type and ratio of each monomer constituting the (meth)acrylic acid ester polymer (A), weight average molecular weight (Mw) of the (meth)acrylic acid ester polymer (A), type of cross-linking agent (B), white coloration A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1, except that the blending amount of the agent (C) and the thickness of the pressure-sensitive adhesive layer were changed as shown in Table 1. However, in Examples 6 to 9, ε-caprolactone-modified tris-(2-acryloxyethyl) isocyanurate (manufactured by Shin-Nakamura Chemical Co., Ltd., product name “NK Ester A-9300”) was used as the active energy ray-curable component (D). -1CL”) and 0.5 parts by mass of 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide as a photopolymerization initiator (E) were further blended to prepare an adhesive composition, The adhesive composition was used to form an active energy ray-curable adhesive layer. The thickness of the pressure-sensitive adhesive layer was changed by changing the thickness and number of layers of the pressure-sensitive adhesive layer formed on the release sheet.

The weight average molecular weight (Mw) described above is a polystyrene-equivalent weight average molecular weight measured under the following conditions using gel permeation chromatography (GPC) (GPC measurement).
<Measurement conditions>
・ GPC measurement device: HLC-8020 manufactured by Tosoh Corporation
・ GPC column (passed in the following order): TSK guard column HXL-H manufactured by Tosoh Corporation
TSK gel GMHXL (x2)
TSK gel G2000HXL
・Measurement solvent: tetrahydrofuran ・Measurement temperature: 40°C

[Test Example 1] (Measurement of gel fraction)
The pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples were cut into a size of 80 mm × 80 mm, the pressure-sensitive adhesive layer was wrapped in a polyester mesh (mesh size 200), and the mass was weighed with a precision balance. By subtracting the individual mass, the mass of the adhesive alone was calculated. Let the mass at this time be M1.

Next, the adhesive wrapped in the polyester mesh was immersed in ethyl acetate at room temperature (23° C.) for 24 hours. After that, the pressure-sensitive adhesive was taken out and air-dried for 24 hours in an environment of 23° C. and 50% relative humidity, and further dried in an oven at 80° C. for 12 hours. After drying, the mass was weighed with a precision balance, and the mass of the adhesive alone was calculated by subtracting the mass of the mesh alone. Let the mass at this time be M2. A gel fraction (%) is represented by (M2/M1)×100. From this, the gel fraction (before UV irradiation) of the adhesive was derived. Table 2 shows the results.

On the other hand, the adhesive layer of the adhesive sheets obtained in Examples 6 to 9 is irradiated with active energy rays (ultraviolet rays; UV) under the following conditions through the light release type release sheet to cure the adhesive layer. let me Regarding the adhesive of the cured adhesive layer, the gel fraction (after UV irradiation) was derived in the same manner as described above. Table 2 shows the results.

<Active energy ray irradiation conditions>
・Using a high-pressure mercury lamp ・Illuminance 200mW/cm ² , Light intensity 2000mJ/cm ²
・Using “UVPF-A1” manufactured by Eye Graphics Co., Ltd. for UV illuminance and photometer

[Test Example 2] (Measurement of L*a*b*)
The light-release type release sheet was peeled off from the pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples, and the exposed pressure-sensitive adhesive layer was applied to a soda-lime glass plate (manufactured by Nippon Sheet Glass Co., Ltd.). Next, the heavy release type release sheet is peeled off from the adhesive layer, and a plastic plate (manufactured by Mitsubishi Gas Chemical Company, Inc., product name " Iupilon Sheet MR58U", thickness: 1 mm) was attached to the surface of the polycarbonate resin plate side, and this was used as a sample.

Using a simultaneous photometric spectrophotometer (manufactured by Nippon Denshoku Industries Co., Ltd., product name "SQ2000"), the surface of the obtained sample on the plastic plate side was measured by CIE 1976 L*a*b* color system in reflected light. The lightness L* (L*M), the chromaticity a* (a*M) and the chromaticity b* (b*M) were measured. Also, from the above results, the color difference ΔE* was calculated by the following formula (I). Table 2 shows the results.

[Test Example 3] (Measurement of total light transmittance)
The pressure-sensitive adhesive layers of the pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples were attached to glass to prepare measurement samples. After performing background measurement on glass, the above measurement sample was measured according to JIS K7361-1: 1997 with a haze meter (manufactured by Nippon Denshoku Industries, product name "NDH-5000"). Transmittance (%) was measured. Table 2 shows the results.

[Test Example 4] (Measurement of haze value)
The pressure-sensitive adhesive layers of the pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples were attached to glass to prepare measurement samples. After performing background measurement with glass, the haze value (total A light haze value (%) was measured. Table 2 shows the results.

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

For the above sample, in accordance with JIS K7244-6, a storage modulus (MPa; before UV irradiation) was measured by a torsional shear method using a viscoelasticity measuring device (manufactured by Physica, product name "MCR300") under the following conditions. It was measured. Table 2 shows the results.
Measurement frequency: 1Hz
Measurement temperature: 23°C

In addition, the adhesive layer of the adhesive sheets obtained in Examples 6 to 9 was irradiated with active energy rays (ultraviolet rays; UV) under the same conditions as in Test Example 1 through the light release type release sheet, and the adhesive The agent layer was cured. The storage elastic modulus (after UV irradiation) of the adhesive of the cured adhesive layer was derived in the same manner as described above. Table 2 shows the results.

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

In an environment of 23 ° C. and 50% RH, the heavy release type release sheet was peeled off from the sample, and the exposed adhesive layer was attached to soda lime glass (manufactured by Nippon Sheet Glass Co., Ltd.). pressure was applied at 0.5 MPa and 50° C. for 20 minutes. After that, it was left under the conditions of 23° C. and 50% RH for 24 hours.

Next, using a tensile tester (manufactured by Orientec, product name "Tensilon"), the adhesive strength (before UV irradiation; N/25 mm) was measured under the conditions of a peel speed of 300 mm/min and a peel angle of 180 degrees. Conditions other than those described here were measured according to JIS Z0237:2009. Table 2 shows the results.

In Examples 6 to 9, after the adhesive layer was attached to the soda lime glass in the same manner as described above, the active energy ray was irradiated under the same conditions as in Test Example 1 through the PET film to remove the adhesive layer. The adhesive strength after curing (after UV irradiation) was also measured. Table 2 shows the results.

[Test Example 7] (Measurement of step follow-up rate)
On the surface of a glass plate (manufactured by NSG Precision Co., Ltd., product name “Corning Glass Eagle XG”, length 90 mm × width 50 mm × thickness 0.5 mm), ultraviolet curable ink (manufactured by Teikoku Ink Co., Ltd., product name “POS-911 ink”) ) was screen-printed into a picture frame (outer shape: 90 mm long, 50 mm wide, 5 mm wide) with a predetermined thickness. Next, ultraviolet rays are irradiated (80 W/cm ² , 2 metal halide lamps, lamp height 15 cm, belt speed 10 to 15 m/min) to cure the printed UV curable ink, and the height of the step due to printing A stepped glass plate having a thickness of any one of 110 μm, 30 μm, 15 μm, 12.5 μm, 10 μm, 7.5 μm and 5 μm was produced.

The light-release type release sheet was peeled off from the pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples, and the exposed pressure-sensitive adhesive layer was covered with a polyethylene terephthalate (PET) film having an easy-adhesion layer (manufactured by Toyobo Co., Ltd., product name "PET A4300", thickness: 100 μm). Next, peel off the heavy release type release sheet to expose the adhesive layer, and use a laminator (manufactured by Fujipla Co., Ltd., product name “LPD3214”) to make the adhesive layer cover the entire surface of the frame-shaped print. Laminated on a glass plate. After that, it was autoclaved for 20 minutes under the conditions of 50° C. and 0.5 MPa, and allowed to stand at normal pressure, 23° C. and 50% RH for 24 hours.

In Examples 6 to 9, an active energy ray was irradiated through the PET film under the same conditions as in Test Example 1 to cure the pressure-sensitive adhesive layer. Then, it was stored for 72 hours under high temperature and high humidity conditions of 85° C. and 85% RH (endurance test). After that, the step followability was evaluated as a step follow-up rate (%) represented by the following formula. Table 2 shows the results.
Level difference follow-up rate (%) = {(height of level difference maintained in a buried state without air bubbles, floating, peeling, etc. after the endurance test (μm))/(thickness of adhesive layer)}×100

[Test Example 8] (Evaluation of black hiding property and appearance harmony)
The adhesive sheets obtained in Examples and Comparative Examples were cut into a length of 70 mm x width of 70 mm, and the adhesive layer of the adhesive sheet was applied to two soda lime glass plates (manufactured by Nippon Sheet Glass Co., Ltd., length of 70 mm x width of 70 mm x thickness). 1.1 mm), and this was used as a sample. In Examples 6 to 9, an active energy ray was irradiated through one of the soda-lime glass plates under the same conditions as in Test Example 1 to cure the pressure-sensitive adhesive layer, which was used as a sample.

The obtained sample is a display part (black) and a frame-shaped white print on a tablet terminal (manufactured by Apple Inc., product name “iPad (registered trademark)”, pixel density: 264 ppi, with a frame-shaped white printed part) Laminated on all sides including both parts. Then, the samples were visually evaluated for black hiding property and appearance harmony based on the following criteria. Table 2 shows the results.

<Evaluation Criteria for Black Concealing Property>
A: The color was white regardless of the viewing angle, and the black color of the display could not be perceived at all.
Good: The display was white when observed obliquely, and the black color of the display could not be perceived at all, but the black color of the display was slightly perceived when observed from the front.
Δ: It is certain that the black color of the display was suppressed, but the black color of the display could be perceived even when observed from an oblique direction.
x: The black color of the display remained strong even when observed from an oblique direction.

<Evaluation Criteria for Appearance Harmony>
A: Regardless of the viewing angle, it was difficult to visually recognize the boundary between the display portion of the tablet terminal and the white printed portion.
◯: The boundary between the display portion of the tablet terminal and the white printed portion was difficult to visually recognize when observed from the front, but the boundary was sufficiently visible depending on the viewing angle.
Δ: The boundary between the display portion of the tablet terminal and the white printed portion was visible even when observed from the front, but the effect of providing the sample was confirmed.
×: Even when observed from the front, there was no change in the visibility of the boundary between the display portion and the white printed portion of the tablet terminal compared to when no sample was provided.

[Test Example 9] (Evaluation of visibility)
On a display with a size of 15.6 inches and a resolution of 1366 × 768 (manufactured by Fujitsu, product name “LITEBOOK A574/H”), various black characters (font: MS P Gothic; “A” to “N”, "A" to "Z" and "0" to "9") were displayed at 100% with a size of 10.5 points.

The sample obtained in Test Example 8 was placed on the display. Then, at a position of 50 cm from the display, it was visually confirmed whether or not the characters could be read, and the visibility was evaluated according to the following criteria. Table 2 shows the results.
A: All characters were legible.
◯: Part of the characters could not be read depending on the type of characters.
x: Most of the characters were unreadable.

As can be seen from Table 2, the products using the pressure-sensitive adhesive sheets obtained in Examples were excellent in the black hiding property, the appearance harmony with the white body, and the visibility.

The pressure-sensitive adhesive sheet of the present invention can be suitably used, for example, for adhering display body constituent members in a display body having a white frame material, a display body hung on a white wall, or the like.

DESCRIPTION OF SYMBOLS 1... Adhesive sheet 11... Adhesive layer 12a, 12b... Release sheet 2... Display body 21... First display body constituent member 22... Second display body constituent member 3... Printed layer 4... Frame material

Claims (8)

A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer for bonding one display body constituent member and another display body constituent member,
two release sheets;
and the adhesive layer sandwiched between the release sheets so as to be in contact with the release surfaces of the two release sheets,
The pressure-sensitive adhesive layer has a color difference ΔE* of less than 95 from completely white, as defined by the CIE1976 L*a*b* color system;
The pressure-sensitive adhesive layer has a total light transmittance of 10% or more,
The adhesive layer has a haze value of 5% or more and 100% or less,
The pressure-sensitive adhesive layer is made of a pressure-sensitive adhesive containing a white colorant and a silane coupling agent.
An adhesive sheet characterized by: The pressure-sensitive adhesive sheet according to claim 1 , wherein the content of the white colorant in the pressure-sensitive adhesive is 0.01% by mass or more and 50% by mass or less. 3. The pressure-sensitive adhesive sheet according to claim 1 , wherein the pressure-sensitive adhesive is an acrylic pressure-sensitive adhesive. The adhesive is a crosslinked adhesive composition containing at least a (meth)acrylic acid ester polymer (A), a crosslinking agent (B) and the white colorant (C). 4. The pressure-sensitive adhesive sheet according to any one of items 1 to 3 . one display body constituent member;
other display body constituent members;
A display body comprising an adhesive layer for adhering the one display body constituent member and the other display body constituent member to each other,
A display, wherein the pressure-sensitive adhesive layer is formed from the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to any one of claims 1 to 4 . 6. The display according to claim 5 , wherein at least one of said one display body constituting member and said other display body constituting member has a step on a side thereof bonded by said pressure-sensitive adhesive layer. 7. A display according to claim 5 , having a white peripheral member. one display body constituent member;
other display body constituent members;
a pressure-sensitive adhesive layer for bonding the one display body constituent member and the other display body constituent member to each other;
A display body comprising
At least one of the one display body constituent member and the other display body constituent member has a step on the side bonded by the pressure-sensitive adhesive layer,
The pressure-sensitive adhesive layer has a color difference ΔE* of less than 95 from completely white, as defined by the CIE1976 L*a*b* color system;
The pressure-sensitive adhesive layer has a total light transmittance of 10% or more,
The adhesive layer has a haze value of 5% or more and 100% or less,
The pressure-sensitive adhesive layer is made of a pressure-sensitive adhesive containing a white colorant
A display body characterized by:

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