JP2021138825A - Adhesive sheet, back-light unit and display device - Google Patents

Abstract

To provide an adhesive sheet excellent in color unevenness suppression, while developing a high haze value, a back-light unit and a display device.SOLUTION: The adhesive sheet 1 having the adhesive layer 11 contains the light diffusing fine particles of which an adhesive agent constitutes the adhesive layer 11, in which an average value of the haze value of the adhesive layer 11 by light of wavelength of 380 nm, the haze value due to light of wavelength of 580 m, and the haze value due to light of the wavelength of 780 nm is 70% or higher and 100% or smaller, the standard variation of the haze value of the adhesive layer 11 by light of wavelength of 380 nm, the haze value due to light of wavelength of 580 m, and the haze value due to light of the wavelength of 780 nm is 7.50 or smaller, and the adhesive layer 1 in which the total light transmission of the adhesive agent layer 11 is 70% or larger.SELECTED DRAWING: Figure 1

Description

The present invention relates to a pressure-sensitive adhesive sheet provided with a light-diffusing pressure-sensitive adhesive layer, and a backlight unit and a display device in which the pressure-sensitive adhesive sheet can be used.

In recent years, electronic devices such as mobile phones, smartphones, tablet terminals, and game machines often use liquid crystal displays as display devices. Since a display unit made of a liquid crystal panel or the like does not emit light by itself, a display device using such a display unit includes a backlight that illuminates the display unit.

Until now, as a method of arranging the light source of the backlight in the above-mentioned display device, a side light type in which the light source is arranged on the side of the light guide plate has been generally used. On the other hand, recently, from the viewpoint of screen brightness and contrast, a direct type backlight in which a light source is arranged directly under the display unit has begun to be studied. In a direct-type backlight, in order to increase the amount of light and to make the amount of light uniform between the center of the screen and the edge of the screen when used as a display device, a large number of light emitters, typically a light emitting diode (LED). ) Is being studied in the direction of being provided on the substrate.

Here, when a large number of light emitters are used as the light source of the direct type backlight, it is desirable to seal the light emitters with a resin or the like because the light emitters have low water resistance. Further, when the display device is manufactured using a backlight having a large number of light emitters as a light source, the obtained image becomes uneven in brightness due to the existence region and the non-existence region of the light emitting body.

Patent Document 1 proposes to provide an adhesive layer containing light-scattering particles on the light emitting body of the backlight described above.

Japanese Patent No. 5590582

However, in Patent Document 1, it is necessary to provide the pressure-sensitive adhesive layer by applying the pressure-sensitive adhesive directly on the backlight. Further, when a conventional adhesive is used, the light from the light source or the diffused light thereof may be unintentionally colored, resulting in color unevenness.

The present invention has been made in view of such an actual situation, and an object of the present invention is to provide an adhesive sheet, a backlight unit, and a display device which are excellent in color unevenness suppressing property while exhibiting a high haze value.

In order to achieve the above object, first, the present invention is a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer, wherein the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer contains light-diffusing fine particles, and the wavelength of the pressure-sensitive adhesive layer. The average value of the haze value due to the light beam of 380 nm, the haze value due to the light beam having a wavelength of 580 nm, and the haze value due to the light beam having a wavelength of 780 nm is 70% or more and 100% or less, and the haze value of the adhesive layer due to the light ray having a wavelength of 380 nm. The standard deviation of the value, the haze value due to the light beam having a wavelength of 580 nm, and the haze value due to the light beam having a wavelength of 780 nm is 7.50 or less, and the total light transmittance of the pressure-sensitive adhesive layer is 70% or more. An adhesive sheet is provided (Invention 1).

In the above invention (Invention 1), while exhibiting a high haze value, unintentional coloring of light from a light source and its diffused light is suppressed, and color unevenness is suppressed. It also has excellent visibility of images and videos when used in display devices.

In the above invention (Invention 1), the total value of the image sharpness of the 0.125 mm, 0.25 mm, 0.5 mm, 1.0 mm and 2.0 mm optical combs of the pressure-sensitive adhesive layer is 0.1 or more. , 400 or less is preferable (Invention 2).

In the above inventions (Inventions 1 and 2), the thickness of the pressure-sensitive adhesive layer is preferably 10 μm or more and 500 μm or less (Invention 3).

In the above inventions (Inventions 1 to 3), the storage elastic modulus G'at 23 ° C. of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is preferably 0.001 MPa or more and 10 MPa or less (Invention 4).

In the above inventions (Inventions 1 to 4), the adhesive strength of the pressure-sensitive adhesive sheet to soda lime glass is preferably 0.1 N / 25 mm or more (Invention 5).

In the above inventions (Inventions 1 to 5), it is preferable that the pressure-sensitive adhesive is an acrylic pressure-sensitive adhesive (Invention 6).

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

The pressure-sensitive adhesive sheet according to the above inventions (Inventions 1 to 7) is preferably used for bonding two hard bodies (Invention 8).

Secondly, the present invention is a backlight unit including a backlight having a plurality of light emitters and an adhesive layer laminated on the backlight, wherein the adhesive layer is the adhesive sheet (Invention 1). To provide a backlight unit characterized by being the pressure-sensitive adhesive layer of 8) (Invention 9).

In the above invention (Invention 9), it is preferable that the light emitting body is a light emitting diode (Invention 10).

Thirdly, the present invention provides a display device including the backlight unit (inventions 9 and 10) and a display unit laminated on the pressure-sensitive adhesive layer of the backlight unit (invention). 11).

The adhesive sheet, the backlight unit, and the display device according to the present invention are excellent in color unevenness suppressing property while exhibiting a high haze value.

It is sectional drawing of the pressure-sensitive adhesive sheet which concerns on one Embodiment of this invention. It is sectional drawing of the backlight unit which concerns on one Embodiment of this invention. It is sectional drawing of the display device which concerns on one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described.
[Adhesive sheet]
The pressure-sensitive adhesive sheet according to an embodiment of the present invention has a pressure-sensitive adhesive layer. FIG. 1 shows a specific configuration as an example of the pressure-sensitive adhesive sheet according to the present embodiment. As shown in FIG. 1, the adhesive sheet 1 according to the embodiment is in contact with the two release sheets 12a and 12b and the release surfaces of the two release sheets 12a and 12b. , 12b and the pressure-sensitive adhesive layer 11 sandwiched between the two. The peeling surface of the release sheet in the present specification means a surface of the release sheet that has peelability, and includes both a surface that has been peeled and a surface that exhibits peelability without peeling. ..

1. 1. Each member 1-1. Adhesive layer The adhesive constituting the adhesive layer 11 contains light diffusing fine particles. The pressure-sensitive adhesive layer 11 has the following physical properties. That is, the average value of the haze value by the light ray having a wavelength of 380 nm, the haze value by the light ray having a wavelength of 580 nm, and the haze value by the light ray having a wavelength of 780 nm is 70% or more and 100% or less, and the haze value and the wavelength by the light ray having a wavelength of 380 nm. The standard deviation of the haze value due to the light beam of 580 nm and the haze value due to the light beam having a wavelength of 780 nm is 7.50 or less, and the total light transmittance is 70% or more. The haze value and the total light transmittance of each of the above rays are values measured according to JIS K7375: 2008.

When the average value of the haze values is 70% or more, it becomes easy to suppress the luminance unevenness, but on the other hand, the color unevenness tends to occur. However, when the standard deviation of the haze value is 7.50 or less, it is possible to suppress color unevenness, and it is possible to suppress unintentional coloring of light from a light source and its diffused light. Further, since the total light transmittance is 70% or more, the visibility of images / videos when used in a display device (the visibility of the display device) is excellent.

From the viewpoint of suppressing brightness unevenness, the average value of the haze values is preferably 80% or more, preferably 86% or more, particularly preferably 88% or more, and further 90%. The above is preferable. The average value of the haze values is 100% or less, preferably 98% or less, particularly preferably 95% or less, and further 94%, from the viewpoint of compatibility with high total light transmittance. It is preferably less than%.

Further, from the viewpoint of suppressing color unevenness, the standard deviation needs to be 7.50 or less, preferably 5.00 or less, particularly preferably 2.50 or less, and further 1 It is preferably .50 or less. On the other hand, the lower limit of the standard deviation is most preferably 0 from the viewpoint of suppressing color unevenness, but is preferably 0.01 or more from the viewpoint of ease of adjusting the value of the standard deviation. In particular, it is preferably 0.10 or more, and more preferably 0.50 or more.

From the viewpoint of visibility of the display device, the total light transmittance needs to be 70% or more, preferably 80% or more, particularly preferably 90% or more, and further 99% or more. Is preferable. The upper limit of the total light transmittance is most preferably 100% from the viewpoint of visibility of the display device.

The total image sharpness of the pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive layer 11 of the present embodiment is 0.125 mm, 0.25 mm, 0.5 mm, 1.0 mm and 2.0 mm measured in accordance with JIS K7374: 2007. , 400 or less, more preferably 300 or less, particularly preferably 200 or less, and further preferably 180 or less. Conventionally, when a display device is manufactured using a backlight having a large number of light emitters as a light source, brightness unevenness may occur in the displayed image due to the presence area and the non-existence area of the light emitting body. However, when the total value of the image sharpness is relatively small as described above, an excellent effect of suppressing luminance unevenness can be obtained.

The total value of the image sharpness is preferably 0.1 or more, more preferably 1 or more, particularly preferably 10 or more, and further preferably 30 or more. As a result, the visibility of the image / video on the obtained display body becomes good.

Here, the image sharpness is measured by measuring the amount of parallel light rays transmitted through the test piece through an optical comb having a transmitting portion and a light-shielding portion. The smaller the width (comb width) between the transmissive portion and the light-shielding portion in the optical comb, the higher the definition of image sharpness. Image sharpness is measured according to the transmission method of JIS K7374: 2007. The specific measurement method is as shown in the test example described later.

The storage elastic modulus G'of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 11 in the present embodiment at 23 ° C. is preferably 0.001 MPa or more, more preferably 0.01 MPa or more, and particularly 0.03 MPa or more. It is preferably 0.05 MPa or more. The storage elastic modulus G'is preferably 10 MPa or less, more preferably 1 MPa or less, particularly preferably 0.20 MPa or less, and further preferably 0.09 MPa or less. When the storage elastic modulus G'is in the above range, excellent unevenness embedding property is obtained, and the illuminant is not only in the initial stage but also under high temperature and high humidity conditions (for example, 85 ° C., 85% RH, 72 hours). It is possible to maintain a state in which the unevenness due to the above-mentioned factors is sufficiently filled with the pressure-sensitive adhesive layer, and it is possible to prevent the unevenness from floating at the interface between the unevenness and the pressure-sensitive adhesive layer and causing peeling or the like. The method for measuring the storage elastic modulus G'in the present specification is as shown in a test example described later.

The average particle size of the light diffusing fine particles contained in the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 11 by the centrifugal sedimentation light transmission method is 0 from the viewpoint of reducing the standard deviation of the haze value and lowering the image sharpness. It is preferably 5.5 μm or more, more preferably 1 μm or more, particularly preferably 2 μm or more, and further preferably 4 μm or more.

Further, from the viewpoint of increasing the average value of the haze value with a small amount of the light diffusing fine particles added, the average particle size of the light diffusing fine particles is preferably 50 μm or less, more preferably 30 μm or less, and particularly preferably 30 μm or less. It is preferably 17 μm or less, and more preferably 13 μm or less.

The average particle size obtained by the centrifugal sedimentation light transmission method is obtained by sufficiently stirring 1.2 g of light diffusing fine particles and 98.8 g of isopropyl alcohol as a measurement sample, and a centrifugal automatic particle size distribution measuring device (HORIBA, Ltd.). It was measured using the product, product name "CAPA-700").

The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 11 is composed of light-diffusing fine particles and other matrices.

In the present embodiment, the absolute value of the difference (refractive index difference) between the refractive index of the matrix of the pressure-sensitive adhesive and the refractive index of the light-diffusing fine particles increases the average value of the haze values and the standard deviation of the haze values. From the viewpoint of keeping the amount low, it is preferably 0.001 or more, more preferably 0.010 or more, particularly preferably 0.020 or more, and further preferably 0.030 or more. Most preferably, it is 0.040 or more. Further, the absolute value of the refractive index difference is preferably 0.5 or less, more preferably 0.2 or less, from the viewpoint of increasing the total light transmittance and lowering the image sharpness. In particular, it is preferably 0.15 or less, and more preferably 0.10 or less.

Here, the method of measuring the refractive index of the matrix is as described in the test example described later. The refractive index of the light diffusing fine particles can be determined by the B method of JIS K7142: 2008.

The refractive index of the adhesive matrix is preferably 1.10 or more, more preferably 1.20 or more, particularly preferably 1.30 or more, and further preferably 1.40 or more. It is preferably 1.45 or more, and most preferably 1.45 or more. The refractive index of the adhesive matrix is preferably 2.00 or less, more preferably 1.80 or less, particularly preferably 1.60 or less, and further preferably 1.50 or less. Is preferable. When the refractive index of the matrix of the pressure-sensitive adhesive is in the above range, the absolute value of the difference in refractive index is likely to fall in the above-mentioned range.

The refractive index of the light diffusing fine particles is preferably 1.10 or more, more preferably 1.20 or more, particularly preferably 1.30 or more, and further preferably 1.40 or more. preferable. The refractive index of the light diffusing fine particles is preferably 2.00 or less, more preferably 1.80 or less, particularly preferably 1.60 or less, and further preferably 1.58 or less. Is preferable. This makes it easier for the absolute value of the refractive index difference to fall within the above-mentioned range.

The content of the light diffusing fine particles in the pressure-sensitive adhesive is preferably 0.1% by mass or more from the viewpoint of easily obtaining a pressure-sensitive adhesive having high haze and low image clarity while reducing the standard deviation of the haze value. It is more preferably 1% by mass or more, particularly preferably 3% by mass or more, and further preferably 5% by mass or more. Further, from the viewpoint of suppressing the storage elastic modulus G'of the pressure-sensitive adhesive, the content of the light-diffusing fine particles in the pressure-sensitive adhesive is preferably 40% by mass or less, more preferably 30% by mass or less, and particularly. It is preferably 20% by mass or less, more preferably 10% by mass or less, and most preferably 8% by mass or less.

The type of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1 according to the present embodiment is not particularly limited as long as it satisfies the above physical properties and does not interfere with the effect of the light-diffusing fine particles. For example, it may be any of an acrylic pressure-sensitive adhesive, a polyester-based pressure-sensitive adhesive, a polyurethane-based pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, and the like. Further, the pressure-sensitive adhesive may be an emulsion type, a solvent type or a solvent-free type, and may be either a crosslinked type or a non-crosslinked type. Among them, an acrylic pressure-sensitive adhesive having excellent adhesive physical properties, optical properties, and the like is preferable. As the acrylic pressure-sensitive adhesive, a cross-linked type is preferable, and a heat-cross-linked type is more preferable.

The pressure-sensitive adhesive in the present embodiment may be an active energy ray-non-curable adhesive or an active energy ray-curable adhesive, but hereinafter, the active energy ray non-curable adhesive is mainly used. Explain to.

Specifically, the pressure-sensitive adhesive in the present embodiment is a pressure-sensitive composition containing a (meth) acrylic acid ester polymer (A), a cross-linking agent (B), and light-diffusing fine particles (C) (hereinafter, "" It may be referred to as "adhesive composition P"), which is preferably crosslinked. The pressure-sensitive adhesive obtained by cross-linking the pressure-sensitive adhesive composition P easily satisfies the above-mentioned physical properties. In addition, 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 "polymer" shall be included in "polymer".

(1) Ingredients (1-1) (meth) acrylic acid ester polymer (A) of the adhesive composition P
The (meth) acrylic acid ester polymer (A) in the present embodiment contains a reactive group-containing monomer having a reactive group in the molecule that reacts with the cross-linking agent (B) as a monomer unit constituting the polymer. Is preferable. The 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), and a pressure-sensitive adhesive having a desired cohesive force can be obtained.

Preferred examples of the reactive group-containing monomer include a monomer having a hydroxyl group in the molecule (hydroxyl group-containing monomer), a monomer having a carboxy group in the molecule (carboxy group-containing monomer), and the like. Among these, a hydroxyl group-containing monomer or a carboxy group-containing monomer having excellent reactivity with the cross-linking agent (B) is preferable.

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and (meth). ) (Meta) Acrylic acid hydroxyalkyl esters such as 3-hydroxybutyl acrylate and 4-hydroxybutyl (meth) acrylic acid can be mentioned. Of these, a (meth) acrylic acid hydroxyalkyl ester having a hydroxyalkyl group having 1 to 4 carbon atoms is preferable from the viewpoint of reactivity with the cross-linking agent (B) and copolymerizability with other monomers. Specifically, for example, 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate and the like are preferable, and 2-hydroxyethyl acrylate or 4-hydroxybutyl acrylate are particularly preferable. Be done. These may be used alone or in combination of two or more.

Examples of the carboxy group-containing monomer include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. Of these, acrylic acid is preferable from the viewpoint of reactivity of the obtained (meth) acrylic acid ester polymer (A) with the cross-linking agent (B) of the carboxy group and copolymerizability with other monomers. 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 value of 1% by mass or more, particularly 6% by mass or more, as a monomer unit constituting the polymer. It is preferable, more preferably 12% by mass or more, and most preferably 17% by mass or more. Further, the (meth) acrylic acid ester polymer (A) preferably contains a reactive group-containing monomer as an upper limit value of 40% by mass or less, particularly 35% by mass or less, as a monomer unit constituting the polymer. It is preferably contained, more preferably 30% by mass or less, and most preferably 25% by mass or less. When the (meth) acrylic acid ester polymer (A) contains a 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 the storage elastic modulus G'and the like described above can be obtained. Physical properties are easily satisfied. Further, the dispersibility of the light diffusing fine particles (C) in the obtained pressure-sensitive adhesive tends to be improved.

Further, 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 carboxy group is an acid component, since the carboxy group-containing monomer is not contained, a transparent conductive film such as tin-doped indium oxide (ITO) or a metal film, which causes a problem due to the acid, is attached to the adhesive. Even if it exists, those defects (corrosion, change in resistance value, etc.) due to acid can be suppressed. However, it is permissible to contain a predetermined amount of the carboxy group-containing monomer so as not to cause such a problem. Specifically, in the (meth) acrylic acid ester polymer (A), the carboxy group-containing monomer is contained in an amount of 0.1% by mass or less, preferably 0.01% by mass or less, more preferably 0.001 as a monomer unit. It is permissible to contain 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, good adhesiveness can be exhibited. The alkyl group may be linear or branched chain.

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 the (meth) acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms include methyl (meth) acrylic acid, ethyl (meth) acrylic acid, propyl (meth) acrylic acid, and n- (meth) acrylic acid. Butyl, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, n-decyl (meth) acrylate, (meth) acrylate Examples thereof include n-dodecyl, myristyl (meth) acrylate, palmityl (meth) acrylate, and stearyl (meth) acrylate. Among them, (meth) acrylic acid ester having 4 to 8 carbon atoms of the alkyl group is preferable, and n-butyl (meth) acrylic acid, ( 2-Ethylhexyl acrylate or isooctyl (meth) acrylate is particularly preferred, and n-butyl acrylate, 2-ethylhexyl acrylate, or isooctyl acrylate is even more preferred. These may be used alone or in combination of two or more.

The (meth) acrylic acid ester polymer (A) preferably contains (meth) acrylic acid alkyl ester in an amount of 30% by mass or more, more preferably 40% by mass or more, as a monomer unit constituting the polymer. It is preferable to contain 50% by mass or more, and more preferably 55% by mass or more. When the lower limit of the content of the (meth) acrylic acid alkyl ester is as described above, the (meth) acrylic acid ester polymer (A) can exhibit suitable adhesiveness and lower the storage elastic modulus G'. Can lead to. On the other hand, the (meth) acrylic acid ester polymer (A) preferably contains (meth) acrylic acid alkyl ester in an amount of 85% by mass or less, and 80% by mass or less, as a monomer unit constituting the polymer. Is more preferable, and it is particularly preferable to contain 75% by mass or less, and further preferably 70% by mass or less. When the upper limit of the content of the (meth) acrylic acid alkyl ester is as described 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 the 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 the monomer in the polymer widens the distance between the polymers, and the above-mentioned physical properties, particularly the storage elastic modulus G', can be easily satisfied.

The alicyclic structure carbon ring in the alicyclic structure-containing monomer may have a saturated structure or may have an unsaturated bond as a part. Further, the alicyclic structure may be a monocyclic alicyclic structure or a polycyclic alicyclic structure such as two rings or three rings. From the viewpoint of making the distance between the obtained (meth) acrylic acid ester polymers (A) appropriate and reducing the storage elastic modulus G', the alicyclic structure is a polycyclic alicyclic structure (polycyclic). Structure) is preferable. Further, in consideration of the compatibility between the (meth) acrylic acid ester polymer (A) and other components, the polycyclic structure is particularly preferably bicyclic to tetracyclic. From the same viewpoint as above, the number of carbon atoms in the alicyclic structure (referring to the total number of carbon atoms in the portion forming the ring, and when a plurality of rings exist independently, the total number of carbon atoms). Is usually 5 or more, and 7 or more is particularly preferable. On the other hand, the upper limit of the number of carbon atoms in the alicyclic structure is not particularly limited, but from the same viewpoint as described above, it is preferably 15 or less, and particularly preferably 10 or less.

Specific examples of the alicyclic structure-containing monomer include cyclohexyl (meth) acrylate, dicyclopentanyl (meth) acrylate, adamantyl (meth) acrylate, isobornyl (meth) acrylate, and (meth) acrylic. Dicyclopentenyl acid, dicyclopentenyloxyethyl (meth) acrylate, etc., among others, dicyclopentanyl (meth) acrylate (carbon number of alicyclic structure:) which exhibits more excellent unevenness embedding property: 10), adamantyl (meth) acrylate (carbon number of alicyclic structure: 10) or isobornyl (meth) acrylate (carbon number of carbon number of alicyclic structure: 7) is preferable, and isobornyl (meth) acrylate is particularly preferable. Further, isobornyl acrylate is preferable. 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, the alicyclic structure-containing monomer is easily satisfied from the above-mentioned storage elasticity G'. The structure-containing monomer is preferably contained in an amount of 1% by mass or more, particularly preferably 5% by mass or more, and further preferably 10% by mass or more. From the same viewpoint as above, the content of the alicyclic structure-containing monomer is preferably 40% by mass or less, particularly preferably 30% by mass or less, and further preferably 20% by mass or less. preferable.

The (meth) acrylic acid ester polymer (A) preferably contains a nitrogen atom-containing monomer as a monomer unit constituting the polymer. By allowing a nitrogen atom-containing monomer to be present in the polymer as a constituent unit, a predetermined polarity is imparted to the pressure-sensitive adhesive, and the adhesive has excellent affinity for an adherend having a certain degree of polarity such as glass. Can be. As the nitrogen atom-containing monomer, a monomer having a nitrogen-containing heterocycle is preferable from the viewpoint of imparting appropriate rigidity to the (meth) acrylic acid ester polymer (A). Further, 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 constituent pressure-sensitive adhesive, the nitrogen atom-containing monomer forms the (meth) acrylic acid ester polymer (A). It is preferable that no reactive unsaturated double bond group is contained other than one polymerizable group used for the polymerization of.

Examples of the monomer having a nitrogen-containing heterocycle include N- (meth) acryloylmorpholin, N-vinyl-2-pyrrolidone, N- (meth) acryloylpyrrolidone, N- (meth) acryloylpiperidin, and N- (meth) acryloyl. Pyrrolidine, N- (meth) acryloyl acryloyl, aziridinyl ethyl (meth) acrylate, 2-vinylpyridine, 4-vinylpyridine, 2-vinylpyrazine, 1-vinylimidazole, N-vinylcarbazole, N-vinylphthalimide, etc. Among them, N- (meth) acryloylmorpholin, which exhibits more excellent adhesive strength, is preferable, and N-acryloylmorpholin is particularly preferable. 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 the nitrogen atom-containing monomer in an amount of 0.1% by mass or more. It is more preferably contained in an amount of 3% by mass or more, particularly preferably 3% by mass or more, and further preferably 8% by mass or more. Further, the (meth) acrylic acid ester polymer (A) preferably contains the nitrogen atom-containing monomer in an amount of 30% by mass or less, and particularly 20% by mass or less, as a monomer unit constituting the polymer. It is preferable, and it is preferable that the content is 14% by mass or less. When the content of the nitrogen atom-containing monomer is within the above range, the obtained pressure-sensitive adhesive can sufficiently exert excellent adhesive strength to glass.

If desired, the (meth) acrylic acid ester polymer (A) may contain another monomer as a monomer unit constituting the polymer. As the other monomer, a monomer containing no reactive functional group is preferable so as not to inhibit the above-mentioned action of the reactive functional group-containing monomer. Examples of such monomers include (meth) acrylic acid alkoxyalkyl esters such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate, vinyl acetate, and styrene. These may be used alone or in combination of two or more.

The (meth) acrylic acid ester polymer (A) is preferably a linear polymer. Since it is a linear polymer, entanglement of molecular chains is likely to occur, and improvement in cohesive force can be expected. Therefore, it is easy to obtain an adhesive having excellent unevenness embedding property under high temperature and high humidity conditions.

Further, the (meth) acrylic acid ester polymer (A) is preferably a solution polymer obtained by a solution polymerization method. Since it is a solution polymer, a high molecular weight polymer can be easily obtained, and an improvement in cohesive force can be expected. Therefore, a pressure-sensitive adhesive having excellent unevenness embedding property under high temperature and high humidity conditions can be easily obtained.

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) acrylic acid ester polymer (A) is preferably 100,000 or more, more preferably 250,000 or more, and particularly preferably 400,000 or more. The weight average molecular weight of the (meth) acrylic acid ester polymer (A) is preferably 3 million or less, particularly preferably 2 million or less, and further preferably 1 million or less. When the weight average molecular weight of the (meth) acrylic acid ester polymer (A) is in the above range, the storage elastic modulus G'and the adhesive strength of the obtained pressure-sensitive adhesive tend to be suitable. Here, the weight average molecular weight in the present specification is a standard polystyrene-equivalent value measured by a gel permeation chromatography (GPC) method.

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) may be any as long as it can react with the reactive group of the (meth) acrylic acid ester polymer (A). Examples of the cross-linking agent (B) include isocyanate-based cross-linking agents, epoxy-based cross-linking agents, amine-based cross-linking agents, melamine-based cross-linking agents, aziridine-based cross-linking agents, hydrazine-based cross-linking agents, aldehyde-based cross-linking agents, oxazoline-based cross-linking agents, and metal alkoxides. Examples thereof include a system cross-linking agent, a metal chelate-based cross-linking agent, a metal salt-based cross-linking agent, and an ammonium salt-based cross-linking agent. The cross-linking agent (B) may be used alone or in combination of two or more.

When the reactive group of the (meth) acrylic acid ester polymer (A) is a hydroxyl group, it is preferable to use an isocyanate-based cross-linking agent having high reactivity with the hydroxyl group. When the reactive group of the (meth) acrylic acid ester polymer (A) is a carboxy group, it is preferable to use an epoxy-based cross-linking agent having high reactivity with the carboxy group.

The isocyanate-based cross-linking agent contains at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, isophorone diisocyanates, and alicyclic polyisocyanates such as hydrogenated diphenylmethane diisocyanate. , And their biurets, isocyanurates, and adducts, which are reactants 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, is preferable from the viewpoint of reactivity with a hydroxyl group.

Examples of the epoxy-based cross-linking agent include 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, N, N, N', N'-tetraglycidyl-m-xylylene diamine, and ethylene glycol diglycidyl ether. , 1,6-Hexanediol diglycidyl ether, trimethylpropan diglycidyl ether, diglycidyl aniline, diglycidyl amine and the like. Of these, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane is preferable from the viewpoint of reactivity with a carboxy group.

The content of the cross-linking agent (B) in the adhesive composition P is preferably 0.001 part by mass or more with respect to 100 parts by mass of the (meth) acrylic acid ester polymer (A), and in particular, 0. It is preferably 01 parts by mass or more, and more preferably 0.1 parts by mass or more. The content of the cross-linking agent (B) is preferably 10 parts by mass or less, and particularly preferably 1 part by mass or less, based on 100 parts by mass of the (meth) acrylic acid ester polymer (A). Further, it is preferably 0.5 parts by mass or less. When the content of the cross-linking agent (B) is in the above range, the storage elastic modulus G', adhesive strength, etc. of the obtained adhesive are likely to be suitable.

(1-3) Light diffusing fine particles (C)
The light diffusing fine particles (C) may be any as long as they exhibit a predetermined light diffusing property and the obtained pressure-sensitive adhesive layer 11 can satisfy the above-mentioned physical characteristics.

Examples of the light diffusing fine particles (C) include inorganic light diffusing fine particles such as silica, calcium carbonate, aluminum hydroxide, magnesium hydroxide, clay, talc, and titanium dioxide; acrylic resin, polystyrene resin, and polyethylene resin. , Epoxy resins, organic light-diffusing particles such as their copolymers or mixtures; The Tospearl series manufactured by Z Japan Co., Ltd.), light-diffusing fine particles of a hybrid of an organic resin and a silicone resin, and the like can be mentioned. Of these, light-diffusing fine particles made of a polymethylmethacrylate-polystyrene copolymer, light-diffusing fine particles made of a silicone resin, or a hybrid light-diffusing fine particle of a polystyrene resin and a silicone resin are preferable. As a result, the obtained pressure-sensitive adhesive layer 11 can easily satisfy the above-mentioned physical properties. The above light diffusing fine particles (C) may be used alone or in combination of two or more.

The shape of the light diffusing fine particles (C) is preferably spherical light diffusing fine particles having uniform light diffusion, but is not limited thereto. The average particle size of the light diffusing fine particles (C) is as described above.

The content of the light diffusing fine particles (C) in the adhesive composition P is the same as the content of the light diffusing fine particles in the above-mentioned pressure-sensitive adhesive.

(1-4) Various Additives The adhesive composition P contains various additives usually used for acrylic pressure-sensitive adhesives, such as silane coupling agents, rust preventives, ultraviolet absorbers, and antistatic agents, if desired. , Adhesives, antioxidants, light stabilizers, softeners, refractive index adjusters and the like can be added. The polymerization solvent and the dilution solvent 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, regardless of whether the adherend is a plastic member or a glass member, the adhesion to the adherend is improved, and the uneven embedding property under high temperature and high humidity conditions becomes more excellent. ..

The silane coupling agent is an organosilicon compound having at least one alkoxysilyl group in the molecule, which has good compatibility with the (meth) acrylic acid ester polymer (A) and has light transmittance. preferable.

Examples of such a silane coupling agent include polymerizable unsaturated group-containing silicon compounds such as vinyltrimethoxysilane, vinyltriethoxysilane, and methacrypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, and 2-(. 3,4-Epoxycyclohexyl) Silicon compounds having an epoxy structure such as ethyltrimethoxysilane, mercapto group-containing silicon compounds such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, and 3-mercaptopropyldimethoxymethylsilane. , Amino group-containing silicon compounds such as 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-Chloropropyltrimethoxysilane, 3-isocyanuspropyltriethoxysilane, 1,6-bis (trimethoxysilyl) hexane, or at least one of these, methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, Examples thereof include a condensate with an alkyl group-containing silicon compound such as ethyltrimethoxysilane. 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 part by mass or more with respect to 100 parts by mass of the (meth) acrylic acid ester polymer (A), and is particularly 0.05. It is preferably parts by mass or more, and more preferably 0.1 parts by mass or more. The content is preferably 1.2 parts by mass or less, particularly preferably 0.8 parts by mass or less, and further preferably 0.4 parts by mass or less.

(2) Preparation of Adhesive Composition P The adhesive composition P produced a (meth) acrylic acid ester polymer (A), and the obtained (meth) acrylic acid ester polymer (A) and a cross-linking agent. It can be prepared by mixing (B) and the light diffusing fine particles (C) and, if desired, adding an additive or the like.

The (meth) acrylic acid ester polymer (A) can be produced by polymerizing a mixture of monomers constituting the polymer by a usual radical polymerization method. The polymerization of the (meth) acrylic acid ester polymer (A) is preferably carried out by a solution polymerization method using a polymerization initiator, if desired. However, the present invention is not limited to this, and polymerization may be carried out without a solvent. Examples of the polymerization solvent include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone and the like, and two or more of them may be used in combination.

Examples of the polymerization initiator include azo compounds and organic peroxides, and two or more of them may be used in combination. Examples of the azo compound include 2,2'-azobisisobutyronitrile, 2,2'-azobis (2-methylbutyronitrile), 1,1'-azobis (cyclohexane1-carbonitrile), and 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 the organic peroxide include benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxy dicarbonate, di-n-propyl peroxy dicarbonate, and di (2-ethoxyethyl) peroxy. Examples thereof include dicarbonate, t-butylperoxyneodecanoate, t-butylperoxyvivarate, (3,5,5-trimethylhexanoyl) peroxide, dipropionyl peroxide, diacetyl peroxide and the like.

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

Once the (meth) acrylic acid ester polymer (A) is obtained, a cross-linking agent (B), light-diffusing fine particles (C) and, if desired, a diluting solvent are added to the solution of the (meth) acrylic acid ester polymer (A). An adhesive composition P (coating solution) diluted with a solvent is obtained by adding an agent or the like and mixing the mixture sufficiently. If any of the above components is in the form of a solid, or if precipitation occurs when the component is mixed with another component in an undiluted state, the component is used alone as a diluting solvent in advance. It may be dissolved or diluted and then mixed with other ingredients.

The diluting solvent is not particularly limited as long as the state of dissolution and dispersion of the adhesive composition P can be maintained, but for example, the same solvent as the polymerization solvent is preferably used.

The concentration and viscosity of the coating solution prepared in this manner may be any range as long as it can be coated, and is not particularly limited and can be appropriately selected depending on the situation. For example, the adhesive composition P is diluted so as to have a concentration of 10 to 60% by mass. It should be noted that the addition of a diluting solvent or the like is not a necessary condition when obtaining the coating solution, and the diluting solvent may not be added as long as the adhesive composition P has a coatable viscosity or the like. In this case, the adhesive composition P becomes a coating solution using the polymerization solvent of the (meth) acrylic acid ester polymer (A) as it is as a diluting solvent.

(3) Formation of Adhesive Layer The pressure-sensitive adhesive layer 11 in the present embodiment is preferably made of a pressure-sensitive adhesive obtained by cross-linking the pressure-sensitive adhesive composition P (coating layer). Crosslinking of the adhesive composition P can usually be carried out by heat treatment. In addition, this heat treatment can also serve as a drying treatment when volatilizing the diluting solvent or the like 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, and particularly 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 (for example, 23 ° C., 50% RH). If this curing period is required, the adhesive is formed after the curing period has elapsed, and if the curing period is not required, after the heat treatment is completed.

By the above heat treatment (and curing), the (meth) acrylic acid ester polymer (A) is crosslinked via the crosslinking agent (B) to obtain a pressure-sensitive adhesive.

(4) Structure of Adhesive Layer The pressure-sensitive adhesive layer 11 in the present embodiment may be composed of a single layer or may be formed by laminating a plurality of layers. Further, in the pressure-sensitive adhesive layer 11 of the present embodiment, a pressure-sensitive adhesive layer (transparent pressure-sensitive adhesive layer) containing no light-diffusing fine particles is provided on one or both sides of the pressure-sensitive adhesive layer (light-diffusing pressure-sensitive adhesive layer) containing light-diffusing fine particles. May be laminated.

When the transparent pressure-sensitive adhesive layer is present as described above, it is preferable that the transparent pressure-sensitive adhesive layer is bonded so as to be located on the surface in contact with the adherend having irregularities. As a result, the light diffusing adhesive layer is suppressed from being compressed or deformed due to the unevenness of the adherend, and the optical laminate (display body) having excellent color unevenness suppressing property and luminance unevenness suppressing property is suppressed. Is obtained.

1-2. Peeling Sheets The peeling sheets 12a and 12b protect the pressure-sensitive adhesive layer 11 until the time when the pressure-sensitive adhesive sheet 1 is used, and are peeled off when the pressure-sensitive adhesive sheet 1 (the pressure-sensitive adhesive layer 11) is used. In the pressure-sensitive adhesive sheet 1 according to the present embodiment, one or both of the release sheets 12a and 12b are not always necessary.

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. Telephthalate 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. In addition, these crosslinked films are also used. Further, these laminated films may be used.

It is preferable that the peeling surfaces (particularly the surfaces in contact with the pressure-sensitive adhesive layer 11) of the peeling sheets 12a and 12b are subjected to a peeling treatment. Examples of the release agent 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 release sheet is a heavy release type release sheet having a large release force and the other release sheet is a light release type release sheet having a small release force.

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

2. Physical Properties (1) Thickness of Adhesive Layer The thickness of the adhesive layer 11 (value measured according to JIS K7130) in the pressure-sensitive adhesive sheet 1 according to the present embodiment is preferably 10 μm or more as a lower limit value, preferably 20 μm. It is more preferably 30 μm or more, and further preferably 40 μm or more. As a result, the unevenness of the backlight can be embedded by the pressure-sensitive adhesive layer 11, and the desired light diffusivity can be obtained. The thickness of the pressure-sensitive adhesive layer 11 is preferably 500 μm or less, more preferably 300 μm or less, particularly preferably 200 μm or less, and further preferably 150 μm or less as an upper limit value. As a result, the desired light diffusivity can be easily obtained, and the processability is also good.

(2) Adhesive Strength The adhesive strength of the pressure-sensitive adhesive sheet 1 according to the present embodiment to soda lime glass is preferably 0.1 N / 25 mm or more, more preferably 1 N / 25 mm or more, and particularly 10 N. It is preferably / 25 mm or more, and more preferably 20 N / 25 mm or more. When the lower limit of the adhesive strength is the above, the uneven embedding property under high temperature and high humidity conditions becomes more excellent. The adhesive strength of the pressure-sensitive adhesive sheet 1 according to the present embodiment to soda lime glass is preferably 70 N / 25 mm or less, more preferably 50 N / 25 mm or less, and 40 N / 25 mm or less as an upper limit value. Is particularly preferable. When the upper limit value of the adhesive force of the adhesive sheet is the above, good reworkability can be obtained, and if a bonding error occurs, an expensive display body component can be reused.

Here, the adhesive strength in the present specification basically refers to the adhesive strength measured by the 180-degree peeling method according to JIS Z0237: 2009, but the measurement sample is 25 mm wide and 100 mm long, and the measured sample is used. It is attached to an adherend, pressurized at 0.5 MPa and 50 ° C. for 20 minutes, left at normal pressure, 23 ° C. and 50% RH for 24 hours, and then measured at a peeling speed of 300 mm / min. It shall be.

3. 3. Production of Adhesive Sheet As an example of production of the adhesive sheet 1, a case where the adhesive composition P is used will be described. The coating liquid of the adhesive composition P is applied to the peeling surface of one of the release sheets 12a (or 12b), heat-treated to heat-crosslink the adhesive composition P to form a coating layer, and then the coating is applied. The peeling surface of the other peeling sheet 12b (or 12a) is superposed on the layer. When the curing period is required, the curing period is set, and when the curing period is not required, the coating layer becomes the adhesive layer 11 as it is. As a result, the adhesive sheet 1 is obtained. The conditions for heat treatment and curing are as described above.

As another production example of the pressure-sensitive adhesive sheet 1, a coating liquid of the pressure-sensitive adhesive composition P is applied to the peeling surface of one of the release sheets 12a, heat-treated to heat-crosslink the pressure-sensitive adhesive composition P, and the coating layer is formed. To obtain a release sheet 12a with a coating layer. Further, the coating liquid of the adhesive composition P is applied to the peeling surface of the other release sheet 12b, heat-treated to heat-crosslink the adhesive composition P to form a coating layer, and the coating layer is attached. To obtain the release sheet 12b of. Then, the release sheet 12a with the coating layer and the release sheet 12b with the coating layer are bonded so that both coating layers are in contact with each other. When the curing period is required, the curing period is set, and when the curing period is not required, the laminated coating layer becomes the pressure-sensitive adhesive layer 11. As a result, the adhesive sheet 1 is obtained. According to this production example, stable production is possible even when the pressure-sensitive adhesive layer 11 is thick.

As a method of applying the coating liquid 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 and the like can be used.

4. Use of Adhesive Sheet The adhesive sheet 1 according to the present embodiment can be suitably used for bonding two hard bodies. It is more difficult to bond hard bodies to each other with an adhesive layer than to bond films to each other or between a film and a hard body, and the yield at the time of bonding tends to decrease. However, the pressure-sensitive adhesive sheet according to the present embodiment. According to No. 1, two hard bodies can be satisfactorily bonded together.

The hard body in the present specification means a member having a bendable angle of less than 90 ° without irreversibly deforming the structure. The angle is preferably less than 60 °, more preferably less than 45 °, particularly preferably less than 10 °, still more preferably less than 5 °. The bendable angle (bending angle) means that when a hard body is placed on a horizontal surface, one end is fixed, and the other end is raised, the angle rises from the horizontal surface. The angle. The hard body may be composed of a single layer or a single member, or may be composed of a plurality of layers or a plurality of members. In the latter case, it is used as one product composed of a plurality of layers or a plurality of members at the time of bonding with the pressure-sensitive adhesive layer, and the product as a whole satisfies the above bending angle, and a part of the product is used. Alternatively, even if the member does not satisfy the above bending angle, the object can be said to be a hard body.

Specifically, the adhesive sheet 1 according to the present embodiment can be suitably used for bonding the backlight to a display unit such as a liquid crystal panel or other hard optical member, as will be described later. .. The backlight and display are usually made of a rigid body. However, the present invention is not limited to this, and can be used for bonding display body constituent members as a desired hard body.

[Backlight unit]
The backlight unit according to the embodiment of the present invention includes a backlight having a plurality of light emitters and an adhesive layer laminated on the backlight. Since the backlight unit has a plurality of light emitters, the surface on the pressure-sensitive adhesive layer side often has irregularities.

FIG. 2 shows a specific configuration as an example of the backlight unit according to the present embodiment. As shown in FIG. 2, the backlight unit 2 according to the embodiment includes a backlight 20 and an adhesive layer 11 laminated on the backlight 20.

1. 1. Component (1) Backlight The backlight 20 includes one or more substrates 21 and a plurality of light emitters 22 provided on the substrate 21. The backlight 20 has irregularities due to a plurality of light emitters 22.

The substrate 21 is not particularly limited, and a substrate generally used for a backlight is used. The substrate 21 is usually a printed circuit board (PCB substrate; Printed Circuit Board).

The substrate 21 may be integrally formed so that a plurality of light emitters 22 are mounted together, or the substrate 21 is separated from each other so that one light emitter 22 is mounted on one substrate 21. It may be formed. When formed separately, each substrate 21 is usually fixed to a frame, a support, a housing, or the like. In the present embodiment, as shown in FIG. 2, it is preferable that the substrate 21 is integrally formed so that a plurality of light emitters 22 are mounted together.

A reflective layer may be formed on the surface of the substrate 21 on the adhesive layer 11 side, or a reflective member may be provided. Thereby, the brightness by the backlight 20 can be effectively improved. As the material of the reflective layer and the reflective member, known materials can be adopted.

Examples of the type of the light emitting body 22 include a light emitting diode (LED), a laser diode (LD), an organic electroluminescence light emitting element, an inorganic electroluminescence light emitting element, and the like. Among these, LEDs are preferable, and mini LEDs or micro LEDs are particularly preferable, from the viewpoint of sealing performance by the pressure-sensitive adhesive layer 11.

The thickness of the illuminant 22 is preferably 5 μm or more, more preferably 50 μm or more, particularly preferably 100 μm or more, and further preferably 200 μm or more. The thickness of the light emitter 22 is preferably 1000 μm or less, particularly preferably 500 μm or less, and further preferably 250 μm or less.

The width of the gap between the light emitting bodies 22 adjacent to each other is preferably 0.01 mm or more, particularly preferably 0.1 mm or more, and further preferably 0.5 mm or more. The width of the gap is preferably 100 mm or less, more preferably 10 mm or less, particularly preferably 4 mm or less, and further preferably 2 mm or less.

The shape of the light emitting body 22 is not particularly limited, but is usually a rectangular parallelepiped shape, a hemispherical shape, or the like. The size of the illuminant 22 is also not particularly limited, but from the viewpoint of illuminant encapsulation, one side or diameter in a plan view is preferably 0.01 to 100 mm, more preferably 0.1 to 10 mm. In particular, it is preferably 0.2 to 5 mm, and more preferably 0.5 to 2 mm.

(2) Adhesive Layer The pressure-sensitive adhesive layer 11 in the present embodiment is preferably the pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1 described above. Further, the pressure-sensitive adhesive layer 11 in the present embodiment is preferably composed of a pressure-sensitive adhesive formed by cross-linking the pressure-sensitive adhesive composition P.

The pressure-sensitive adhesive layer 11 in the present embodiment embeds the unevenness of the light emitting body 22. That is, the plurality of light emitters 22 are sealed by the pressure-sensitive adhesive layer 11 without any voids. As a result, the water resistance is improved, and the light emitting body 22 (particularly the LED) can be protected from moisture. Further, the pressure-sensitive adhesive layer 11 diffuses the light emitted from the backlight 20. Then, by having the above-mentioned physical properties, it is possible to suppress unintentional coloring of the light from the light source and the diffused light thereof, that is, the occurrence of color unevenness is effectively suppressed.

The pressure-sensitive adhesive layer 11 may be laminated in direct contact with the backlight 20, or may be indirectly laminated via another layer or member.

2. Manufacture of Backlight Unit In order to manufacture the backlight unit 2 according to the present embodiment, for example, one of the release sheets 12a of the pressure-sensitive adhesive sheet 1 is peeled off, and the exposed pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet 1 is removed from the backlight 20. It is bonded to the surface on the side where the light emitting body 22 of the above exists.

Next, the other release sheet 12b is peeled from the pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1 at a desired timing. The peeling of the release sheet 12b is preferably performed when the display device 3 described later is manufactured, and it is preferable to protect the pressure-sensitive adhesive layer 11 with the release sheet 12b until then.

3. 3. Other Configuration A sealing material may be provided between the backlight 20 and the pressure-sensitive adhesive layer 11. Even in that case, irregularities are often formed on the surface of the sealing material opposite to the backlight 20, and these irregularities can be absorbed by the pressure-sensitive adhesive layer 11.

Further, another pressure-sensitive adhesive layer may be laminated between the backlight 20 and the pressure-sensitive adhesive layer 11. Even in such a case, the pressure-sensitive adhesive layer 11 can mitigate the influence of the uneven embedding by the other pressure-sensitive adhesive layer.

Further, two or more layers of the sealing material and the pressure-sensitive adhesive layer may be laminated between the backlight 20 and the pressure-sensitive adhesive layer 11.

[Display device]
A display device according to an embodiment of the present invention includes a backlight unit according to the above-described embodiment and a display unit laminated on an adhesive layer of the backlight unit. The display unit may be laminated in direct contact with the pressure-sensitive adhesive layer, or may be indirectly laminated via another layer or member.

A display device as an example in this embodiment is shown in FIG.
As shown in FIG. 3, the display device 3 according to the present embodiment includes the backlight unit 2 described above and a display unit 30 laminated on the adhesive layer 11 of the backlight unit 2. The backlight 20 in the display device 3 corresponds to a direct type backlight.

Examples of the type of display device 3 include a liquid crystal display (LCD), a light emitting diode (LED) display, an organic electroluminescence (organic EL) display, electronic paper, and the like. The display device 3 may be a touch panel. Among the above, a liquid crystal display (liquid crystal display device) having a high need for a backlight is preferable.

The display unit 30 includes, for example, a liquid crystal panel, but is not limited thereto, and is used in combination with, for example, a part of the constituent members of the liquid crystal panel or for adding or enhancing the function of the liquid crystal panel. It may be an optical member (for example, a light diffusing plate, an ultraviolet absorbing filter, etc.). As the display unit 30, a known one can be adopted.

In order to manufacture the display device 3 according to the present embodiment, the adhesive layer 11 exposed in the backlight unit 2 and the display unit 30 are bonded together. When the release sheet 12b is laminated on the pressure-sensitive adhesive layer 11, the release sheet 12b is peeled off to expose the pressure-sensitive adhesive layer 11, and then the pressure-sensitive adhesive layer 11 and the display unit 30 are attached to each other. Stick them together.

In manufacturing the display device 3 according to the present embodiment, the pressure-sensitive adhesive layer 11 may be attached to the display unit 30 first, and then the pressure-sensitive adhesive layer 11 and the backlight 20 may be attached to each other.

Here, a desired optical member may be provided between the pressure-sensitive adhesive layer 11 and the display unit 30, or on the surface of the display unit 30 opposite to the pressure-sensitive adhesive layer 11. Examples of such an optical member include a brightness improving film, a contrast improving film, a viewing angle compensating film, a transparent conductive film, a liquid crystal polymer film, a semitransmissive reflective film, a shatterproof film, and a light diffusing plate.

The embodiments described above are described for facilitating the understanding of the present invention, and are not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

For example, either one of the release sheets 12a and 12b in the adhesive sheet 1 may be omitted.

Hereinafter, 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. 1. Preparation of (meth) acrylic acid ester polymer 30 parts by mass of 2-ethylhexyl acrylate, 30 parts by mass of n-butyl acrylate, 10 parts by mass of isobonyl acrylate, 10 parts by mass of N-acryloyl morpholine and 20 parts by mass of 2-hydroxyethyl acrylate A (meth) acrylic acid ester polymer (A) was prepared by copolymerizing parts by mass. When the molecular weight of this (meth) acrylic acid ester polymer (A) was measured by the method described later, the weight average molecular weight (Mw) was 500,000.

2. Preparation of Adhesive Composition 100 parts by mass (solid content conversion value; the same applies hereinafter) of the (meth) acrylic acid ester polymer (A) obtained in the above step (1) and trimethylolpropane as a cross-linking agent (B). Light composed of 0.2 parts by mass of modified tolylene diisocyanate (manufactured by Toyochem, product name "BHS8515") and silicone resin (silicon-containing compound having an intermediate structure between inorganic and organic) as light diffusing fine particles (C). Diffused fine particles (C1; manufactured by Momentive Performance Materials Japan, product name "Tospearl 145", average particle size: 4.5 μm, refractive index: 1.43) 7.5 parts by mass and as a silane coupling agent A coating solution of the adhesive composition was obtained by mixing 0.13 parts by mass of 3-glycidoxypropyltrimethoxysilane (Si1) of the above, stirring well, and diluting with methyl ethyl ketone.

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 the abbreviations and the like shown in Table 1 are as follows.
[(Meta) acrylic acid ester polymer (A)]
2EHA: 2-ethylhexyl acrylate BA: n-butyl acrylate IBXA: isobornyl acrylate ACMO: N-acryloylmorpholin HEA: 2-hydroxyethyl acrylate AA: acrylate 4HBA: 4-hydroxybutyl acrylate EA: ethyl acrylate
[Crosslinking agent (B)]
B1: Trimethylolpropane-modified tolylene diisocyanate (manufactured by Toyochem, product name "BHS8515")
B2: Trimethylolpropane-modified xylylene diisocyanate (manufactured by Soken Chemical Co., Ltd., product name "TD-75")
B3: 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane B4: aluminum tris (acetylacetone)
[Light diffusing fine particles (C)]
C1: Light-diffusing fine particles made of silicone resin (silicon-containing compound having an intermediate structure between inorganic and organic) (manufactured by Momentive Performance Materials Japan, product name "Tospearl 145", average particle size: 4.5 μm , Refractive index: 1.43)
C2: Light-diffusing fine particles (manufactured by Momentive Performance Materials Japan, product name "Tospearl 1100", average particle size: 11 μm, refractive index) made of silicone resin (silicon-containing compound having an intermediate structure between inorganic and organic) Rate: 1.43)
C3: Spherical polymethyl methacrylate-polystyrene copolymer fine particles (manufactured by Sekisui Plastics Co., Ltd., product name "XX-13LA", average particle size: 4 μm, refractive index: 1.565)
C4: Light-diffusing fine particles composed of silicone resin and polystyrene resin (manufactured by Nippon Shokubai Co., Ltd., product name "Soliostar RA-Y50X", average particle size: 5 μm, refractive index: 1.57)
C5: Light-diffusing fine particles made of silicone resin (silicon-containing compound having an intermediate structure between inorganic and organic) (manufactured by Momentive Performance Materials Japan, product name "Tospearl 120", average particle size: 2 μm, refractive index Rate: 1.43)
C6: Light diffusing fine particles composed of melamine resin and benzoguanamine resin (manufactured by Nippon Shokubai Co., Ltd., product name "Eposter M-30", average particle size: 3 μm, refractive index: 1.66)
[Silane coupling agent]
Si1: 3-glycidoxypropyltrimethoxysilane Si2: A-50 (manufactured by Soken Chemical Co., Ltd.)

3. 3. Manufacture of Adhesive Sheet Peeling of a heavy-release type release sheet (manufactured by Lintec Corporation, product name "SP-PET752150") in which one side of a polyethylene terephthalate film is peeled off with a silicone-based release agent from the obtained coating solution of the adhesive composition. The treated surface was coated with a knife coater and then heat-treated at 90 ° C. for 1 minute to form a coated layer.

Next, the coating layer on the heavy-release type release sheet obtained above and the light-release type release sheet obtained by peeling one side of the polyethylene terephthalate film with a silicone-based release agent (manufactured by Lintec Corporation, product name "SP-PET38131"). And are bonded so that the peeled surface of the light peeling type peeling sheet comes into contact with the coating layer, and the heavy peeling type peeling sheet / the coating layer of the adhesive layer (thickness: 50 μm) / the light peeling type peeling sheet An adhesive sheet having a composition was produced.

The thickness of the pressure-sensitive adhesive layer is a value measured using a constant pressure thickness measuring device (manufactured by Teclock Co., Ltd., product name "PG-02") in accordance with JIS K7130 (the same applies hereinafter).

[Examples 2 to 10, Comparative Example 1]
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 and blending amount of the cross-linking agent (B). , The type and amount of the light diffusing fine particles (C), the type and amount of the silane coupling agent, and the thickness of the pressure-sensitive adhesive layer are changed as shown in Table 1, and the pressure-sensitive adhesive sheet is the same as in Example 1. Manufactured. In Example 7, two layers of a pressure-sensitive adhesive layer having a thickness of 50 μm were laminated to form a pressure-sensitive adhesive layer having a thickness of 100 μm.

The above-mentioned weight average molecular weight (Mw) is a polystyrene-equivalent weight average molecular weight measured under the following conditions (GPC measurement) using gel permeation chromatography (GPC).
<Measurement conditions>
-GPC measuring device: HLC-8020 manufactured by Tosoh Corporation
-GPC column (passed in the following order): TSK guard volume 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 refractive index)
An adhesive composition was prepared in the same manner as in each Example and Comparative Example except that the light diffusing fine particles were not blended. Then, using the adhesive composition, an adhesive sheet was produced in the same manner as in each Example and Comparative Example. The refractive index of the pressure-sensitive adhesive layer of the obtained pressure-sensitive adhesive sheet was adjusted according to JIS K0062-1992 using an Abbe refractometer (manufactured by Atago Co., Ltd., product name "Abe refractometer DR-M2", Na light source, wavelength: 589 nm). And measured. This measurement result corresponds to the refractive index of the adhesive matrix. The results are shown in Table 1.

In addition, the difference between the measured refractive index of the pressure-sensitive adhesive matrix and the refractive index of the light-diffusing fine particles used in each Example and Comparative Example was calculated as an absolute value. The results are shown in Table 2.

[Test Example 2] (Measurement of haze value)
The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheets produced in Examples and Comparative Examples was bonded to glass, and this was used as a measurement sample. After performing background measurement with glass, the above measurement sample is 5 nm from 380 nm to 780 nm using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "NDH7000") according to JIS K7375: 2008. The haze value (%) in the light rays of the wavelength of the interval was measured. Table 2 shows the haze value (haze value of all light rays) (%) and the haze value (%) of light rays having wavelengths of 380 nm, 580 nm and 780 nm. In addition, the average value and standard deviation of the haze values in the light rays having wavelengths of 380 nm, 580 nm and 780 nm were calculated. The results are also shown in Table 2.

[Test Example 3] (Measurement of total light transmittance)
The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheets produced in Examples and Comparative Examples was bonded to glass, and this was used as a measurement sample. After performing background measurement with glass, the total light transmittance (%) of the above measurement sample using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "NDH5000") according to JIS K7375: 2008. ) Was measured. The results are shown in Table 2.

[Test Example 4] (Measurement of image sharpness)
For the adhesive layer of the adhesive sheet produced in Examples and Comparative Examples, a mapping property measuring instrument (manufactured by Suga Test Instruments Co., Ltd., product name "ICM-10P") was used, and the permeation method of JIS K7374: 2007 was compliant. The image sharpness (%) of five types of optical combs (comb width: 0.125 mm, 0.25 mm, 0.5 mm, 1.0 mm and 2.0 mm) was measured, and the total value was calculated. The results are shown in Table 2.

[Test Example 5] (Measurement of storage elastic modulus)
The release sheet was peeled off from the pressure-sensitive adhesive sheets produced in each Example and Comparative Example, and a plurality of layers of the pressure-sensitive adhesive layer were laminated so as to have a thickness of 800 μm. A cylinder (height 800 μm) having a diameter of 8 mm was punched out from the obtained laminated body of the pressure-sensitive adhesive layer, and this was used as a sample.

The above sample is subjected to a torsional shear method using a viscoelasticity measuring device (manufactured by Physica, product name "MCR300") in accordance with JIS K7244-6, and has a storage elastic modulus (G') at 23 ° C. under the following conditions. MPa) was measured. The results are shown in Table 2.
Measurement frequency: 1Hz
Measurement temperature: 23 ° C

[Test Example 6] (Measurement of adhesive strength)
The light release type release sheet is peeled off from the adhesive sheets produced in Examples and Comparative Examples, and the exposed adhesive layer is a polyethylene terephthalate (PET) film having an easy adhesive layer (manufactured by Toyobo Co., Ltd., product name "PET A4300", It was bonded to an easy-adhesive layer having a thickness of 100 μm) to obtain a laminate of a heavy-release type release sheet / adhesive layer / PET film. The obtained laminate was cut into a width of 25 mm and a length of 100 mm.

In an environment of 23 ° C. and 50% RH, the heavy-release type release sheet is peeled off from the above laminate, and the exposed adhesive layer is attached to soda lime glass (manufactured by Nippon Sheet Glass Co., Ltd.), and then an autoclave manufactured by Kurihara Seisakusho Co., Ltd. Pressurized at 0.5 MPa and 50 ° C. for 20 minutes. Then, it was left for 24 hours under the condition of 23 ° C. and 50% RH, and this was used as a sample. Then, using a tensile tester (manufactured by Orientec Co., Ltd., product name "Tencilon"), the adhesive strength (before UV; N / 25 mm) was measured under the conditions of a peeling speed of 300 mm / min and a peeling angle of 180 degrees. Conditions other than those described here were measured in accordance with JIS Z0237: 2009. The results are shown in Table 2.

[Test Example 7] (Evaluation of color unevenness suppression)
The light release type release sheet is peeled off from the adhesive sheets manufactured in Examples and Comparative Examples, and the exposed adhesive layer is attached to a soda lime glass plate (manufactured by Nippon Sheet Glass Co., Ltd., thickness: 0.7 mm) for heavy peeling. A laminate consisting of a mold release sheet / adhesive layer / soda lime glass plate was obtained.

The laminated body was held over a three-wavelength fluorescent lamp (distance from the fluorescent lamp: 200 cm), and the color of the fluorescent lamp and the light diffused around it, which was visible through the laminated body, was observed. Then, the color unevenness suppression property was evaluated according to the following criteria. The results are shown in Table 2.
◎… There was no color unevenness even when the holding angle was changed, and the color was white as a whole.
〇… Depending on the angle of holding, the fluorescent lamp part appears to be slightly colored (red, etc.), but at an angle where no coloring is seen, it is white as a whole.
Δ: The part of the fluorescent lamp appears to be slightly colored (red, etc.) regardless of the holding angle, but the light diffused around the fluorescent lamp is white.
×… The part of the fluorescent lamp was clearly colored (red, etc.) regardless of the holding angle, and the light diffused around the fluorescent lamp also appeared to be colored.

[Test Example 8] (Evaluation of brightness unevenness suppression)
Enomoto lead frame (product name "5050 D / G PKG"), Genelite LED (product name "B3838ECI1"), Tanaka Kikinzoku gold wire (product name "GLF = 30"), Shinetsu Chemical Co., Ltd. sealed A 5 mm x 5 mm square LED point light source (total luminous flux 20 lumens) using a stop resin (product name "KJR-9022") and a die bond agent manufactured by Shin-Etsu Chemical Co., Ltd. (product name "KER3000-M2"). Made. Next, four LED point light sources obtained were fixed on a black resin substrate in a quadrangular arrangement at 5 mm intervals to obtain a pseudo backlight.

A pseudo display device having a backlight unit was obtained by placing the laminate produced in Test Example 7 on the pseudo-backlight so that the heavy-release type release sheet side was in contact with the pseudo-backlight. The LED point light source was turned on, the appearance of the point light source was visually confirmed from a position 30 cm directly above the pseudo display device, and the brightness unevenness suppression property was evaluated according to the following criteria. The results are shown in Table 2.
◎… The point light source could not be seen at all.
〇… When I stared at it, I could see the point light source, but it was almost unnoticeable.
×… The point light source was clearly visible.

[Test Example 9] (Evaluation of uneven embedding property)
On the surface of a glass plate (manufactured by NSG Precision Co., Ltd., product name "Corning Glass Eagle XG", length 90 mm x width 50 mm x thickness 0.5 mm), UV curable ink (manufactured by Teikoku Inks, product name "POS-911 ink") ) Was screen-printed in a frame shape (outer shape: length 90 mm × width 50 mm, width 5 mm). Next, the printed ultraviolet curable ink is cured by irradiating with ultraviolet rays (80 W / cm ² , 2 metal halide lamps, lamp height 15 cm, belt speed 10 to 15 m / min), and a step (height of the step) due to printing is cured. A stepped glass plate having one of 15 μm, 20 μm, 25 μm, and 50 μm) was prepared.

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

The obtained evaluation sample was autoclaved for 30 minutes under the conditions of 50 ° C. and 0.5 MPa, and then left at normal pressure at 23 ° C. and 50% RH for 24 hours. Then, it was stored for 72 hours under high temperature and high humidity conditions of 85 ° C. and 85% RH (durability test), and then the unevenness embedding property was evaluated. The unevenness embedding property is judged by whether or not the printing step (unevenness) is completely filled by the adhesive layer, and if air bubbles, floating, peeling, etc. are observed at the interface between the printing step and the adhesive layer, It is determined that the printing step (unevenness) was not filled by the adhesive layer. Here, the uneven embedding property was calculated as the step follow-up rate (%) represented by the following formula, and evaluated according to the following criteria. The results are shown in Table 2.
Step follow-up rate (%) = {(After the durability test, the height of the step maintained in a buried state without bubbles, floating, peeling, etc. (μm)) / (Thickness of adhesive layer (μm)} × 100
<Evaluation criteria for embedding unevenness>
◎… Step follow rate 40% or more ○… Step follow rate less than 40%, 30% or more ×… Step follow rate less than 30%

As can be seen from Table 2, the adhesive sheet produced in the examples was excellent in color unevenness suppressing property. In addition, the adhesive sheets produced in Examples 1 to 8 and 10 were also excellent in suppressing uneven brightness. Further, the pressure-sensitive adhesive sheets produced in Examples 1 to 9 were also excellent in uneven embedding property.

The adhesive sheet and the backlight unit according to the present invention are suitable for display devices that require color unevenness suppression, particularly liquid crystal display devices and the like.

1 ... Adhesive sheet 11 ... Adhesive layer 12a, 12b ... Release sheet 2 ... Backlight unit 20 ... Backlight 21 ... Substrate 22 ... Light emitter 3 ... Display device 30 ... Display unit

Claims (11)

An adhesive sheet having an adhesive layer
The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer contains light-diffusing fine particles.
The average value of the haze value of the pressure-sensitive adhesive layer due to the light beam having a wavelength of 380 nm, the haze value due to the light beam having a wavelength of 580 nm, and the haze value due to the light beam having a wavelength of 780 nm is 70% or more and 100% or less.
The standard deviations of the haze value of the pressure-sensitive adhesive layer due to the light beam having a wavelength of 380 nm, the haze value due to the light beam having a wavelength of 580 nm, and the haze value due to the light beam having a wavelength of 780 nm are 7.50 or less.
A pressure-sensitive adhesive sheet having a total light transmittance of 70% or more of the pressure-sensitive adhesive layer. The total image sharpness of the 0.125 mm, 0.25 mm, 0.5 mm, 1.0 mm and 2.0 mm optical combs of the pressure-sensitive adhesive layer is 0.1 or more and 400 or less. The adhesive sheet according to claim 1. The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the thickness of the pressure-sensitive adhesive layer is 10 μm or more and 500 μm or less. The pressure-sensitive adhesive sheet according to any one of claims 1 to 3, wherein the storage elastic modulus G'of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer at 23 ° C. is 0.001 MPa or more and 10 MPa or less. The adhesive sheet according to any one of claims 1 to 4, wherein the adhesive force of the adhesive sheet with respect to soda lime glass is 0.1 N / 25 mm or more. The pressure-sensitive adhesive sheet according to any one of claims 1 to 5, wherein the pressure-sensitive adhesive is an acrylic pressure-sensitive adhesive. The adhesive sheet includes two release sheets.
The pressure-sensitive adhesive sheet according to any one of claims 1 to 6, wherein the pressure-sensitive adhesive layer is sandwiched between the release sheets so as to be in contact with the peel-off surfaces of the two release sheets. The adhesive sheet according to any one of claims 1 to 7, wherein the adhesive sheet is used for bonding two hard bodies. A backlight with multiple illuminants and
A backlight unit including an adhesive layer laminated on the backlight.
A backlight unit, wherein the pressure-sensitive adhesive layer is the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to any one of claims 1 to 8. The backlight unit according to claim 9, wherein the light emitting body is a light emitting diode. With the backlight unit according to claim 9 or 10.
A display device including a display unit laminated on the pressure-sensitive adhesive layer of the backlight unit.

Images