KR20200081215A - Adhesive sheet for pasting backlight and backlight unit - Google Patents

Abstract

The present invention is to provide an adhesive sheet for backlight attachment which is attached to a backlight provided with a plurality of light-emitting bodies on a substrate to allow the light-emitting bodies to be encapsulated without gaps; and a backlight unit formed as the adhesive sheet for backlight attachment is attached to a backlight. To achieve the purpose, the present invention provides an adhesive sheet (1) for backlight attachment, which has an adhesive layer (11) attached to a backlight (20) having a plurality of light-emitting bodies (22) provided on a substrate (21) to encapsulate the light-emitting bodies (22), wherein the adhesive layer (11) has a storage modulus of 0.001-0.15 MPa at 50°C, a gel fraction of an adhesive constituting the adhesive layer (11) is 10-75%, and the adhesive layer (11) has a thickness of 110 μm or more.

Description

ADHESIVE SHEET FOR PASTING BACKLIGHT AND BACKLIGHT UNIT

The present invention relates to a display unit made of a liquid crystal panel or various optical members, a display device having a backlight that illuminates the display unit, and the like, an adhesive sheet for attaching a backlight attached to a backlight, and a backlight unit in which an adhesive layer is attached to the backlight. It is about.

2. Description of the Related Art In recent electronic devices such as mobile phones, smart phones, tablet terminals, and game machines, liquid crystal displays are frequently used as display bodies (displays). Since the display portion made of a liquid crystal panel or the like does not emit light by itself, the display device is configured to include a display portion and a backlight that illuminates the display portion.

As a method of arranging a light source of a backlight in a display device, there are a side light type in which a light source is disposed on a side of the light guide plate, and a direct light type in which a light source is disposed directly below the display unit. And, from the viewpoint of screen brightness and contrast, direct-type backlights have become mainstream. In the direct-type backlight, a plurality of light-emitting bodies, typically light-emitting diodes (LEDs), are provided on a substrate in order to ensure the amount of light and to make the light uniform.

Here, the display device is usually made by bonding and fixing the display portion and the backlight with an adhesive sheet. As such an adhesive sheet, what is disclosed by patent documents 1 and 2 is mentioned, for example. The pressure-sensitive adhesive sheet has a planar frame shape, and the display portion and backlight are bonded together at their periphery. Therefore, the inside of the pressure-sensitive adhesive sheet on the frame is an air gap, and an air layer is present.

Japanese Patent No. 5268268 Japanese Patent Publication No. 2007-059386

However, when an air layer is present inside the display device as described above, there is a problem that the reflection loss of light due to the difference in refractive index between the air layer and the layer adjacent to the air layer is large, and the image quality of the display device is deteriorated.

In order to solve the above problem, it is conceivable to stick the adhesive sheet to the entire surface of the backlight, however, as described above, a plurality of LEDs are provided on the substrate of the backlight. Conventionally, there has been no adhesive sheet that can be attached to the front surface of such a backlight so that voids disappear. For example, the pressure-sensitive adhesive sheets disclosed in Patent Documents 1 and 2, although having a predetermined performance in use as a frame-like portion, do not have sufficient performance to directly and without sticking to a large number of LEDs.

On the other hand, instead of using an adhesive sheet, it is also possible to form an adhesive layer by coating the adhesive on the front surface of the backlight, but there is a problem that productivity is poor.

This invention is made|formed in view of the above-mentioned real image, and the adhesive sheet for backlight affixing which can attach to the backlight provided with a plurality of light emitters on a substrate so that the light emitter is sealed without voids, and such a back light affix An object of the present invention is to provide a backlight unit formed by attaching a pressure-sensitive adhesive sheet to a backlight.

In order to achieve the above object, firstly, the present invention is a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer adhered so that the light-emitting body is sealed in a backlight provided with a plurality of light-emitting bodies on a substrate, and the pressure-sensitive adhesive layer is stored at 50°C. The elastic modulus is 0.001 MPa or more, 0.15 MPa or less, and the gel fraction of the adhesive constituting the adhesive layer is 10% or more and 75% or less, and the thickness of the adhesive layer is 110 µm or more. An adhesive sheet is provided (Invention 1).

According to the invention (invention 1), by having the above-described physical properties of the pressure-sensitive adhesive layer, it is possible to attach the pressure-sensitive adhesive layer to the backlight provided with a plurality of light-emitting bodies on a substrate so that the light-emitting bodies are sealed without voids.

In the above invention (Invention 1), it is preferable that the storage elastic modulus at 23°C of the pressure-sensitive adhesive layer is 0.01 MPa or more and 0.20 MPa or less (Invention 2).

In the said invention (invention 1, 2), it is preferable that the said adhesive is an acrylic adhesive (invention 3).

In the above invention (Inventions 1 to 3), it is preferable to include the two release sheets and the pressure-sensitive adhesive layer interposed on the release sheet so as to contact the release surface of the two release sheets (invention). 4).

Secondly, the present invention is a backlight unit having a backlight provided with a plurality of light emitters on one or two or more substrates, and an adhesive layer attached to the backlight so that the light emitter is sealed, wherein the adhesive layer is for attaching the backlight. Provided is a backlight unit characterized by being an adhesive layer of an adhesive sheet (Inventions 1 to 4) (Invention 5).

In the above invention (Invention 5), it is preferable that the luminous body is a light emitting diode (Invention 6).

The adhesive sheet for attaching a backlight according to the present invention can be attached to a backlight provided with a plurality of light-emitting bodies on a substrate so that the light-emitting bodies are sealed without voids. Further, in the backlight unit according to the present invention, since the pressure-sensitive adhesive layer is affixed to the backlight so that a plurality of light-emitting bodies on the substrate are sealed without voids, it is possible to suppress deterioration of image quality in the obtained display body.

1 is a cross-sectional view of an adhesive sheet for attaching a backlight according to an embodiment of the present invention.
2 is a cross-sectional view of a backlight unit according to an embodiment of the present invention.
3 is a cross-sectional view of a liquid crystal display device according to an exemplary embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described.

(Adhesive sheet for back light attachment)

The adhesive sheet for attaching a backlight according to an embodiment of the present invention (in this specification, it is simply referred to as an "adhesive sheet" in this specification) is attached to a backlight provided with a plurality of light emitters on a substrate so that the light emitters are sealed. An adhesive layer is provided, Preferably, it consists of laminating a release sheet on one side or both surfaces of the said adhesive layer.

1 shows a specific configuration as an example of the pressure-sensitive adhesive sheet for attaching a backlight according to the present embodiment.

As shown in Fig. 1, the adhesive sheet (adhesive sheet) 1 for attaching the backlight is in contact with the release surfaces of the two release sheets 12a, 12b and the two release sheets 12a, 12b. It consists of the adhesive layer 11 pinched by the said 2 sheets of peeling sheets 12a, 12b. In addition, the peeling surface of the peeling sheet in this specification means the surface which has peelability in a peeling sheet, and includes both the surface which performed peeling treatment and the surface which shows peelability even if it does not perform peeling treatment.

1. Each member

1-1. Adhesive layer

The pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1 according to the present embodiment has a storage modulus at 50°C of 0.001 MPa or more and 0.15 MPa or less, and a gel fraction of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 11 is 10. % Or more, 75% or less, and a thickness of 110 µm or more.

Since the pressure-sensitive adhesive layer 11 has the above-described properties, the pressure-sensitive adhesive sheet 1 according to the present embodiment adheres the pressure-sensitive adhesive layer 11 so that the light-emitting body is sealed in the backlight provided with a plurality of light-emitting bodies on the substrate without voids. can do. Thereby, since an air layer or a void disappears between the display portion and the backlight in the obtained display device or the like, it is possible to prevent deterioration of image quality due to reflection loss of light.

Specifically, since the storage modulus of the pressure-sensitive adhesive layer 11 at 50°C is 0.15 MPa or less, and the gel fraction of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 11 is 75% or less, the pressure-sensitive adhesive layer 11 ) Exhibits excellent flexibility and stress relaxation, making it easy to embed light emitters, so that the light emitters can be sealed without voids.

On the other hand, a plurality of light-emitting bodies provided in the backlight may generate heat by luminescence, and when a plurality of light-emitting bodies are provided, the pressure-sensitive adhesive layer 11 is exposed to high temperature conditions (durability). When the storage elastic modulus of the pressure-sensitive adhesive layer 11 at 50°C is 0.001 MPa or more, and the gel fraction is 10% or more, even under the above-described durability conditions, the bag without voids caused by the pressure-sensitive adhesive layer 11 is It becomes easy to maintain.

From the viewpoint of embedding properties of the luminous body, the storage elastic modulus of the pressure-sensitive adhesive layer 11 at 50°C is preferably 0.13 MPa or less, particularly preferably 0.09 MPa or less, and even more preferably 0.05 MPa or less. In addition, from the viewpoint of the encapsulating property of the luminous body under endurance conditions, the storage elastic modulus is preferably 0.01 MPa or more, particularly preferably 0.02 MPa or more, and even more preferably 0.03 MPa or more.

From the viewpoint of embedding properties of the luminous body, the gel fraction of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 11 is preferably 70% or less, particularly preferably 64% or less, and even more preferably 57% or less. Moreover, from the viewpoint of the light-emitting body sealing property under endurance conditions, the gel fraction is preferably 20% or more, more preferably 30% or more, particularly preferably 40% or more, and even more preferably 50% or more.

On the other hand, the storage elastic modulus at 23°C of the pressure-sensitive adhesive layer 11 is preferably 0.20 MPa or less, more preferably 0.18 MPa or less, particularly preferably 0.15 MPa or less, and particularly 0.11 MPa or less from the viewpoint of emitter embedability. More preferred. In addition, from the viewpoint of the encapsulating property of the luminous body under endurance conditions, the storage modulus is preferably 0.01 MPa or more, particularly preferably 0.02 MPa or more, and even more preferably 0.04 MPa or more.

In addition, the storage elastic modulus in this specification is made into the value measured by the torsional shearing method at the measurement frequency of 1 Hz based on JISK7244-6. It is as showing in the test example mentioned later specifically,. In addition, the measuring method of the gel fraction of an adhesive is as showing in the test example mentioned later.

The pressure-sensitive adhesive layer 11 has the above-described storage elastic modulus and gel fraction, and has a thickness of 110 µm or more, so that the light-emitting body can be sealed depending on the type of the light-emitting body. From the viewpoint of sealing the light-emitting body, the thickness of the pressure-sensitive adhesive layer 11 is preferably 130 μm or more, particularly preferably 160 μm or more, and even more preferably 200 μm or more. On the other hand, from the viewpoint of reducing the thickness of the resulting display body, the thickness of the pressure-sensitive adhesive layer 11 is preferably 1000 μm or less, particularly preferably 800 μm or less, and more preferably 500 μm or less.

The ratio of the thickness of the pressure-sensitive adhesive layer 11 to the thickness of the light-emitting body (thickness of the pressure-sensitive adhesive layer/thickness of the light-emitting body) is preferably 1.1 or more, more preferably 1.4 or more, from the viewpoint of reliably sealing the light-emitting body. It is particularly preferable that it is higher, and more preferably 2.2 or higher. On the other hand, the ratio of the thickness is preferably 10 or less, more preferably 8 or less, particularly preferably 5 or less, and even more preferably 2.9 or less from the viewpoint of reducing the thickness of the resulting display body.

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-described physical property values. For example, acrylic pressure-sensitive adhesives, polyester-based pressure-sensitive adhesives, polyurethane-based Any of an adhesive, a rubber-based adhesive, and a silicone-based adhesive may be used. Moreover, the said adhesive may be either 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 that easily satisfies the above-described physical property values is preferable.

The acrylic pressure-sensitive adhesive may be active energy ray-curable or active energy ray-curable, but is preferably an active energy ray non-curable acrylic pressure-sensitive adhesive that does not require a photopolymerization initiator. As the active energy ray non-curable acrylic pressure-sensitive adhesive, a crosslinked type is particularly preferable, and a heat crosslinked type is more preferable.

It is preferable that the said adhesive is made by cross-linking the adhesive composition containing (meth)acrylic acid ester polymer (A) and a crosslinking agent (B) (it may be called "adhesive composition P" hereafter) especially. In addition, in this specification, (meth)acrylic acid means both acrylic acid and methacrylic acid. The same is true for other similar terms. In addition, the concept of "copolymer" is also included in "polymer".

(1) Components of the adhesive composition

(1-1) (meth)acrylic acid ester polymer (A)

It is preferable that (meth)acrylic acid ester polymer (A) in this embodiment contains the reactive group containing monomer which has the reactive group which reacts with a crosslinking agent (B) in a molecule|numerator as a monomer unit which comprises the said polymer. The reactive group derived from the reactive group-containing monomer reacts with the crosslinking agent (B) to form a crosslinked structure (three-dimensional network structure), and it is easy to obtain an adhesive having the above gel fraction and storage elastic modulus.

Examples of the reactive group-containing monomer include a monomer having a hydroxyl group in the molecule (a 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. Among these, a hydroxyl group-containing monomer is particularly preferable from the viewpoint of suppressing the storage elastic modulus to be low.

Examples of the hydroxyl group-containing monomer include (meth)acrylic acid 2-hydroxyethyl, (meth)acrylic acid 2-hydroxypropyl, (meth)acrylic acid 3-hydroxypropyl, (meth)acrylic acid 2-hydroxybutyl, ( And (meth)acrylic acid hydroxyalkyl esters such as meta-acrylic acid 3-hydroxybutyl and (meth)acrylic acid 4-hydroxybutyl. Among them, (meth)acrylic acid having a hydroxyalkyl group having 1 to 4 carbon atoms from the viewpoint of the reactivity of the hydroxyl group in the (meth)acrylic acid ester polymer (A) obtained with the crosslinking agent (B) and copolymerization with other monomers. Hydroxyalkyl esters are preferred. Specifically, for example, 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and the like are preferably mentioned. In particular, 2-hydroxyethyl acrylate or 4-hydroxybutyl acrylate Preferably. These may be used alone or in combination of two or more.

Examples of the carboxyl group-containing monomer include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. Especially, acrylic acid is preferable from the viewpoint of the reactivity of the carboxyl group in the (meth)acrylic acid ester polymer (A) with the crosslinking agent (B) and copolymerization with other monomers. These may be used alone or in combination of two or more.

As an amino group containing monomer, (meth)acrylic acid aminoethyl, (meth)acrylic acid n-butylaminoethyl, etc. are mentioned, for example. These may be used alone or in combination of two or more.

The (meth)acrylic acid ester polymer (A), as a monomer unit constituting the polymer, preferably contains 3% by mass or more of a reactive group-containing monomer, and particularly preferably contains 10% by mass or more, 15 It is more preferable to contain more than mass%. Further, the (meth)acrylic acid ester polymer (A) is preferably a monomer unit constituting the polymer, and preferably contains 35% by mass or less of a reactive group-containing monomer, and particularly preferably 30% by mass or less. , It is more preferable to contain 25% by mass or less. When the (meth)acrylic acid ester polymer (A) contains a reactive group-containing monomer in the above-mentioned amount as a monomer unit, the above-described storage elastic modulus and gel fraction are liable to be obtained.

Moreover, it is also preferable that the (meth)acrylic acid ester polymer (A) does not contain a carboxyl group-containing monomer as a monomer unit constituting the polymer. Since the carboxyl group is an acid component, it does not contain a carboxyl group-containing monomer, so that defects are generated by the acid on the object to which the pressure-sensitive adhesive is attached, for example, a sealing resin for a light-emitting body, a metal wiring for a substrate, a metal reflective film on a substrate, etc. Even in the presence of these, it is possible to suppress their defects (deterioration, corrosion, etc.) caused by acids. However, it is permissible to contain a predetermined amount of the carboxyl group-containing monomer to such an extent that such defects do not occur. Specifically, in the (meth)acrylic acid ester polymer (A), as a monomer unit, those containing a carboxyl group-containing monomer in an amount of 0.1% by mass or less, preferably 0.01% by mass or less, and more preferably 0.001% by mass or less Is allowed.

It is preferable that the (meth)acrylic acid ester polymer (A) 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.

As the (meth)acrylic acid alkyl ester, from the viewpoint of adhesion, a (meth)acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group is preferable. Examples of the (meth)acrylic acid alkyl ester having 1 to 20 carbon atoms of the alkyl group include, for example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, and (meth)acrylic acid. n-pentyl, (meth)acrylic acid n-hexyl, (meth)acrylic acid 2-ethylhexyl, (meth)acrylic acid isooctyl, (meth)acrylic acid n-decyl, (meth)acrylic acid n-dodecyl, (meth)acrylic acid Steel, (meth)acrylic acid palmityl, (meth)acrylic acid stearyl, and the like. Especially, from the viewpoint of further improving adhesiveness, (meth)acrylic acid esters having 1 to 8 carbon atoms of the alkyl group are preferred, and methyl (meth)acrylate, n-butyl (meth)acrylate, or 2-ethylhexyl (meth)acrylate This is particularly preferred. Moreover, these may be used individually or may be used in combination of 2 or more type.

The (meth)acrylic acid ester polymer (A) is a monomer unit constituting the polymer, preferably contains 30% by mass or more of (meth)acrylic acid alkyl ester, more preferably 40% by mass or more, and 50% by mass. It is particularly preferable to contain at least %, and more preferably at least 55% by mass. 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 favorable adhesiveness. Further, the (meth)acrylic acid ester polymer (A) is preferably a monomer unit constituting the polymer, and preferably contains 97% by mass or less of (meth)acrylic acid alkyl ester, more preferably 90% by mass or less, It is particularly preferable to contain 80% by mass or less, and more preferably 70% by mass or less. When the upper limit of the content of the (meth)acrylic acid alkyl ester is the above, other monomer components such as a reactive functional group-containing monomer can be introduced into the (meth)acrylic acid ester polymer (A) in a suitable amount, and the gel fraction or storage elastic modulus can be adjusted. It becomes easy.

It is also preferable that the said (meth)acrylic acid ester polymer (A) contains the monomer (alicyclic structure containing monomer) which has an alicyclic structure in a molecule|numerator as a monomer unit which comprises the said polymer. Since the alicyclic structure-containing monomer is bulky, it is estimated that the gap between the polymers is widened by presenting it in the polymer, and the obtained adhesive can be made excellent in flexibility. On the other hand, the alicyclic structure-containing monomer itself can impart a certain degree of hardness to the polymer. Therefore, the (meth)acrylic acid ester polymer (A) has an alicyclic structure-containing monomer as a constituent monomer unit, so that the gel fraction or storage elastic modulus of the obtained pressure-sensitive adhesive, particularly the storage elastic modulus at 50°C, is adjusted to the above-mentioned range. It becomes easy.

The carbon ring of the alicyclic structure in the alicyclic structure-containing monomer may be of a saturated structure or may have a partially unsaturated bond. In addition, the alicyclic structure may be a monocyclic alicyclic structure, or a polycyclic alicyclic structure such as bicyclic or tricyclic. In the same manner as described above, from the viewpoint of adjusting the physical properties of the pressure-sensitive adhesive obtained, the alicyclic structure is preferably a polycyclic alicyclic structure (polycyclic structure). Moreover, considering the compatibility of the (meth)acrylic acid ester polymer (A) with other components, the polycyclic structure is particularly preferably bicyclic to tetracyclic. In addition, in the same manner as described above, from the viewpoint of adjusting the physical properties of the resulting pressure-sensitive adhesive, the number of carbon atoms in the alicyclic structure (referring to the total number of carbon atoms in a portion forming a ring, and the total number of carbon atoms when a plurality of rings exist independently) It is preferable that it is 5 or more normally, and it is especially preferable that it is 7 or more. On the other hand, the upper limit of the number of carbon atoms of the alicyclic structure is not particularly limited, but from the viewpoint of compatibility similarly to the above, it is preferably 15 or less, and particularly preferably 10 or less.

As said alicyclic structure containing monomer, specifically, (meth)acrylic acid cyclohexyl, (meth)acrylic acid dicyclopentanyl, (meth)adamantyl acrylate, (meth)acrylic acid isobornyl, (meth)acrylic acid dicyclophene And (meth)acrylic acid dicyclopentenyloxyethyl. Among them, (meth)acrylic acid dicyclopentanyl which exhibits superior emitter embedding property (carbon number of alicyclic structure: 10), (meth) Adamantyl acrylate (carbon number in alicyclic structure: 10) or isobornyl (meth)acrylate (carbon number in alicyclic structure: 7) is preferable, and (meth) isobornyl acrylate 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 an alicyclic structure-containing monomer as a monomer unit constituting the polymer, it is preferable to contain 1% by mass or more of the alicyclic structure-containing monomer, and 5% by mass or more It is particularly preferable to contain, and more preferably to contain 9% by mass or more. In addition, the (meth)acrylic acid ester polymer (A) is a monomer unit constituting the polymer, preferably contains 30% by mass or less of an alicyclic structure-containing monomer, and particularly preferably contains 25% by mass or less, 20 It is more preferable to contain it by mass% or less. When the content of the alicyclic structure-containing monomer is in the above-mentioned range, adjustment of the obtained pressure-sensitive adhesive to the above-described physical property values becomes easy.

Moreover, it is also preferable that the said (meth)acrylic acid ester polymer (A) contains a nitrogen atom containing monomer as a monomer unit which comprises the said polymer. When the nitrogen atom-containing monomer is present in the polymer as a structural unit, it is possible to impart a predetermined polarity to the pressure-sensitive adhesive and to have excellent affinity for an adherend having a certain degree of polarity such as glass. As the above-mentioned nitrogen atom-containing monomer, nitrogen-containing clothing is used from the viewpoint of providing a suitable stiffness to the (meth)acrylic acid ester polymer (A), increasing the gel fraction, and increasing the storage elastic modulus at 50°C of the obtained pressure-sensitive adhesive to a predetermined degree. Preferred is a monomer having a summon. In addition, from the viewpoint of increasing the degree of freedom of the portion derived from the nitrogen atom-containing monomer among the high-order structure of the pressure-sensitive adhesive, the nitrogen atom-containing monomer is one polymerization used for polymerization to form the (meth)acrylic acid ester polymer (A). It is preferable not to contain a reactive unsaturated double bond group other than the sexual group. Moreover, the above-mentioned reactive functional group-containing monomer is excluded from the nitrogen atom-containing monomer referred to herein.

As a monomer having a nitrogen-containing heterocycle, for example, N-(meth)acryloylmorpholine, N-vinyl-2-pyrrolidone, N-(meth)acryloylpyrrolidone, N-(meth) Acryloylpiperidine, N-(meth)acryloylpyrrolidine, N-(meth)acryloylaziridine, aziridinylethyl (meth)acrylate, 2-vinylpyridine, 4-vinylpyridine, 2- Vinyl pyrazine, 1-vinylimidazole, N-vinylcarbazole, N-vinyl phthalimide, and the like. Among them, N-(meth)acryloylmorpholine exhibiting more excellent adhesion is preferable. , 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 is preferable to contain 1% by mass or more of the nitrogen atom-containing monomer, and 2% by mass or more. It is particularly preferable, and it is more preferable to contain 3% by mass or more. In addition, the (meth)acrylic acid ester polymer (A) is preferably a monomer unit constituting the polymer, and preferably contains 20% by mass or less of the nitrogen atom-containing monomer, and particularly preferably 15% by mass or less, 10 It is more preferable to contain it by mass% or less. When the content of the nitrogen atom-containing monomer is within the above-described range, the resulting pressure-sensitive adhesive becomes easy to adjust the storage elastic modulus and gel fraction at 50°C within the above-mentioned range.

The (meth)acrylic acid ester polymer (A) may contain other monomers as a monomer unit constituting the polymer, if desired. As another monomer, in order not to inhibit the above-described action of the reactive functional group-containing monomer, a monomer not containing the reactive functional group is preferable. Examples of such monomers include (meth)acrylic acid alkoxyalkyl esters such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate, vinyl acetate, styrene, and the like. These may be used alone or in combination of two or more.

It is preferable that (meth)acrylic acid ester polymer (A) is a linear polymer. By being a linear polymer, entanglement of the molecular chain is liable to occur, and it is easy to obtain an adhesive having the above-described gel fraction.

Moreover, it is preferable that (meth)acrylic acid ester polymer (A) is a solution polymerization product obtained by the solution polymerization method. By being a solution polymerization product, it is easy to obtain a high-molecular-weight polymer, and an adhesive with more excellent light-encapsulator sealing property under endurance conditions can be expected because improvement in cohesion is expected. In addition, the amount of remaining monomer in the pressure-sensitive adhesive is reduced, and the light resistance is excellent.

The polymerization aspect 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 200,000 or more, particularly preferably 300,000 or more, and even more preferably 400,000 or more as the lower limit. When the lower limit of the weight average molecular weight of the (meth)acrylic acid ester polymer (A) is the above, it is easy to satisfy the lower limit of the above-described gel fraction and storage elastic modulus.

In addition, the weight average molecular weight of the (meth)acrylic acid ester polymer (A) is preferably 2 million or less, particularly preferably 1.5 million or less, and more preferably 1 million or less. When the upper limit of the weight average molecular weight of the (meth)acrylic acid ester polymer (A) is the above, it is easy to meet the upper limit of the storage elastic modulus described above. In addition, the weight average molecular weight in this specification is the value of the standard polystyrene conversion measured by the gel permeation chromatography (GPC) method.

Moreover, in the adhesive composition P, (meth)acrylic acid ester polymer (A) may be used individually by 1 type, or may be used in combination of 2 or more type.

(1-2) Crosslinking agent (B)

The crosslinking agent (B) can crosslink the (meth)acrylic acid ester polymer (A) by heating the adhesive composition P, and it is possible to form a three-dimensional network structure satisfactorily. Thereby, the cohesion force of the obtained adhesive improves, and it becomes easy to adjust the gel fraction and storage elastic modulus of the obtained adhesive to the above-mentioned range.

The crosslinking agent (B) may be any one that reacts with a reactive group of the (meth)acrylic acid ester polymer (A), for example, an isocyanate-based crosslinking agent, epoxy-based crosslinking agent, amine-based crosslinking agent, melamine-based crosslinking agent, aziridine-based crosslinking agent, hydrazine And crosslinking agents based on aldehydes, aldehyde crosslinking agents, oxazoline crosslinking agents, metal alkoxide crosslinking agents, metal chelate crosslinking agents, metal salt crosslinking agents, and ammonium salt crosslinking agents. Among the above, when the reactive group of the (meth)acrylic acid ester polymer (A) is a hydroxyl group, it is preferable to use an isocyanate-based crosslinking agent having excellent reactivity with the hydroxyl group, and the reactivity of the (meth)acrylic acid ester polymer (A) When the group is a carboxy group, it is preferable to use an epoxy-based crosslinking agent having excellent reactivity with the carboxy group. Moreover, the crosslinking agent (B) can be used individually by 1 type or in combination of 2 or more type.

The isocyanate crosslinking agent contains at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate and xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, and hydrogenated diphenylmethane diisocyanate. Adducts, which are reactants with alicyclic polyisocyanates such as isocyanates, and their low molecular weight active hydrogen-containing compounds such as burette, isocyanurate, and ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil. And sieve. Among them, from the viewpoint of reactivity with hydroxyl groups, trimethylolpropane-modified aromatic polyisocyanates, particularly trimethylolpropane-modified tolylene diisocyanate and trimethylolpropane-modified xylylene diisocyanate are preferred.

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

The content of the crosslinking agent (B) in the adhesive composition P is preferably 0.01 parts by mass or more, particularly preferably 0.05 parts by mass or more, and particularly preferably 0.1 parts by mass or more, relative to 100 parts by mass of the (meth)acrylic acid ester polymer (A). It is more preferable. Further, the content is preferably 10 parts by mass or less, particularly preferably 5 parts by mass or less, and more preferably 0.4 parts by mass or less. When the content of the crosslinking agent (B) is in the above range, the above-described storage elastic modulus and gel fraction are liable to be satisfied.

(1-3) Various additives

To the adhesive composition P, if desired, various additives commonly used in acrylic adhesives, such as silane coupling agents, ultraviolet absorbers, antistatic agents, tackifiers, antioxidants, light stabilizers, softeners, refractive index modifiers, rust inhibitors, etc., are added. can do. In addition, it is assumed that the polymerization solvent or dilution solvent described later is not included in the additive constituting the adhesive composition P.

It is preferable that the adhesive composition P contains a silane coupling agent among the above. As a result, adhesion to an optical member such as a backlight (light-emitting body, a substrate, a reflective film) as an adherend or a diffusion member is improved, and the sealing property of the luminous body under durable conditions is more excellent.

As a silane coupling agent, as an organosilicon compound which has at least 1 alkoxysilyl group in a molecule|numerator, it is preferable that it has good compatibility with a (meth)acrylic acid ester polymer (A), and has light transmittance.

Examples of the silane coupling agent include silicon compounds containing polymerizable unsaturated groups such as vinyl trimethoxysilane, vinyl triethoxysilane and methacryloxypropyl trimethoxysilane, and 3-glycidoxypropyl trimethoxysilane. , Silicon compounds having an epoxy structure such as 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercapto Mercapto group-containing silicon compounds such as propyldimethoxymethylsilane, 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, and N-(2-aminoethyl)- Amino group-containing silicon compounds such as 3-aminopropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, 3-isocyanatepropyltriethoxysilane, or at least one of these, and methyltriethoxysilane and ethyltriethoxy And condensates with alkyl group-containing silicon compounds such as silane, methyltrimethoxysilane, and 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 parts by mass or more, particularly preferably 0.05 parts by mass or more, and particularly preferably 0.1 parts by mass or more with respect to 100 parts by mass of the (meth)acrylic acid ester polymer (A). More preferred. Moreover, it is preferable that this content is 1 mass part or less, it is especially preferable that it is 0.5 mass part or less, and it is more preferable that it is 0.3 mass part or less.

(2) Preparation of adhesive composition

The adhesive composition P can be produced by preparing the (meth)acrylic acid ester polymer (A), mixing the obtained (meth)acrylic acid ester polymer (A) with the crosslinking agent (B), and adding additives as desired. have.

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. It is preferable to perform polymerization of (meth)acrylic acid ester polymer (A) by solution polymerization method using a polymerization initiator as desired. As a polymerization solvent, ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone, etc. are mentioned, for example, You may use two or more types together.

As a polymerization initiator, an azo-type compound, an organic peroxide, etc. are mentioned, You may use 2 or more types together. Examples of the azo-based compound include 2,2'-azobisisobutyronitrile, 2,2'-azobis (2-methylbutyronitrile), and 1,1'-azobis (cyclohexane 1-carbonyl Tril), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile), dimethyl2,2'- Azobis (2-methylpropionate), 4,4'-azobis (4-cyanovaleric acid), 2,2'-azobis (2-hydroxymethylpropionitrile), 2,2'- And azobis[2-(2-imidazolin-2-yl)propane].

As the organic peroxide, for example, benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di(2-ethoxyethyl)peroxydicarbonate , t-butyl peroxy neodecanoate, t-butyl peroxy pivalate, (3,5,5-trimethylhexanoyl) peroxide, dipropionyl peroxide, diacetyl peroxide, and the like.

Moreover, in the said polymerization process, the weight average molecular weight of the polymer obtained can be adjusted by mix|blending a chain transfer agent, such as 2-mercaptoethanol.

When the (meth)acrylic acid ester polymer (A) is obtained, a solution of the (meth)acrylic acid ester polymer (A) is added to the solution of the crosslinking agent (B) and, if desired, a diluting solvent and additives, and mixed thoroughly to obtain a solvent. A diluted adhesive composition P (coating solution) is obtained. In addition, in any one of the above components, when a solid one is used, or when precipitation occurs when mixed with other components in an undiluted state, the components are dissolved alone in a dilution solvent in advance or After dilution, you may mix with other components.

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, methanol, ethanol, propanol, butanol, and 1-me Alcohols such as ethoxy-2-propanol, ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone, cyclohexanone, esters such as ethyl acetate and butyl acetate, and cellosolve solvents such as ethyl cellosolve, etc. Is used.

The concentration and viscosity of the coating solution thus prepared may be in a range that 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 to a concentration of 10 to 60% by mass. Moreover, in obtaining a coating solution, addition of a diluting solvent or the like is not a necessary condition, and as long as the adhesive composition P has a coatable viscosity or the like, it is not necessary to add a diluting solvent. In this case, the adhesive composition P becomes a coating solution using the polymerization solvent of the (meth)acrylic acid ester polymer (A) 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 in which the pressure-sensitive adhesive composition P (coating layer) is crosslinked. Crosslinking of the adhesive composition P can usually be performed by heat treatment. Moreover, this heat treatment can also be used as a drying treatment when a diluting solvent or the like is volatilized from the coating layer of the adhesive composition P applied to a desired object.

The heating temperature of the heat treatment is preferably 50 to 150°C, and particularly preferably 70 to 120°C. Further, 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 at room temperature (for example, 23°C, 50% RH) may be provided. When this curing period is required, after the curing period has elapsed, and when the curing period is unnecessary, the pressure-sensitive adhesive is formed after the heat treatment is finished.

The (meth)acrylic acid ester polymer (A) is sufficiently crosslinked via the crosslinking agent (B) by the heat treatment (and curing) described above. The pressure-sensitive adhesive obtained in this way becomes easy to satisfy the above-described physical property values.

(4) Physical properties of the adhesive

The amount of monomer contained in the pressure-sensitive adhesive in the present embodiment, and the residual amount of the monomer mainly used for copolymerization of the (meth)acrylic acid ester polymer (A), is preferably 10% by mass or less, particularly preferably 1% by mass or less, and 0.1 More preferably, it is less than mass%. Thereby, the obtained adhesive layer 11 becomes excellent in light resistance, and can be suppressed from discoloring even if it is used for a long time in contact with a plurality of light-emitting bodies that emit light.

The lower limit of the amount of the monomer contained in the pressure-sensitive adhesive in the present embodiment is most preferably 0% by mass, but is usually preferably 0.001% by mass or more, particularly preferably 0.005% by mass or more.

1-2. Release sheet

The release sheets 12a and 12b protect the pressure-sensitive adhesive layer 11 until use of the pressure-sensitive adhesive sheet 1, 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 necessarily required.

As the release sheet 12a, 12b, for example, polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polyethylene Naphthalate film, polybutylene terephthalate film, polyurethane film, ethylene vinyl acetate film, ionomer resin film, ethylene·(meth)acrylic acid copolymer film, ethylene·(meth)acrylic acid ester copolymer film, polystyrene film, poly Carbonate films, polyimide films, fluororesin films, and the like are used. Moreover, these crosslinked films are also used. Moreover, these laminated films may be sufficient.

It is preferable that the peeling treatment is performed on the peeling surfaces of the peeling sheets 12a and 12b (especially the surface contacting the pressure-sensitive adhesive layer 11). Examples of the release agent used for the release treatment include alkyd-based, silicone-based, fluorine-based, unsaturated polyester-based, polyolefin-based, and wax-based release agents. Moreover, among the release sheets 12a and 12b, it is preferable that one release sheet is a medium peeling release sheet having a large peeling force, and the other release sheet is a light peeling release sheet having a small peeling force.

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

2. Properties

(1) Total light transmittance

The total light transmittance (value measured according to JIS K7361-1:1997) of the pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1 according to the present embodiment is preferably 90% or more, particularly preferably 93% or more, It is more preferable that it is 95% or more. When the total light transmittance is the above, the transparency is high, which makes it suitable for the application of the backlight.

In addition, the total light transmittance of the pressure-sensitive adhesive layer 11 after placing the pressure-sensitive adhesive sheet 1 according to the present embodiment under conditions of 50°C and 50% RH for 500 hours is preferably 90% or more, particularly preferably 93% or more. And more preferably 95% or more. If the total light transmittance is the above, the transparency is high even when the heat-generating condition of the light-emitting body in contact with the pressure-sensitive adhesive layer 11 continues for a long time, making it more suitable for attaching the backlight.

Moreover, the total light transmittance of the pressure-sensitive adhesive layer 11 after irradiating ultraviolet rays with an illuminance of 500 mW/m 2 for 500 hours with respect to the pressure-sensitive adhesive sheet 1 according to the present embodiment is preferably 90% or more, particularly preferably 93% or more. , It is more preferably at least 95%. When the total light transmittance is the above, it can be said that the light resistance is excellent even under conditions in which the light emitting state of the light emitting body contacting the pressure-sensitive adhesive layer 11 continues for a long time, and is more suitable for attaching the backlight.

(2) Haze value

The haze value of the pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1 according to the present embodiment is preferably 30% or less, more preferably 20% or less, particularly preferably 10% or less, and even more preferably 1% or less. Do. When the haze value of the adhesive layer 11 is the above, it is excellent in light transmittance and is suitable for affixing a backlight. In addition, the haze value is a characteristic value including the thickness of the pressure-sensitive adhesive layer, and it is preferable to satisfy the haze value regardless of the thickness of the pressure-sensitive adhesive layer.

Even if the pressure-sensitive adhesive layer 11 in this embodiment has a thickness of 250 µm, it is easy to satisfy the haze value. In the pressure-sensitive adhesive sheet 1 according to the present embodiment, the low haze value as described above can be achieved by using the pressure-sensitive adhesive composition P described above.

In addition, the haze value of the pressure-sensitive adhesive layer 11 after placing the pressure-sensitive adhesive sheet 1 according to the present embodiment under conditions of 50°C and 50% RH for 500 hours is preferably 30% or less, and more preferably 20% or less. It is particularly preferably 10% or less, and more preferably 1% or less. When the haze value is the above, the transparency is high even when the heat-generating condition of the light-emitting body in contact with the pressure-sensitive adhesive layer 11 continues for a long time, and is more suitable for attaching the backlight.

In addition, the haze value of the pressure-sensitive adhesive layer 11 after irradiating ultraviolet rays with an illuminance of 500 mW/m 2 for 500 hours with respect to the pressure-sensitive adhesive sheet 1 according to the present embodiment is preferably 30% or less, more preferably 20% or less , It is particularly preferably 10% or less, and more preferably 1% or less. When the total light transmittance is the above, it can be said that the light resistance is excellent even under conditions in which the light emitting state of the light emitting body contacting the pressure-sensitive adhesive layer 11 continues for a long time, and is more suitable for attaching the backlight.

Moreover, under any conditions, the lower limit of the haze value of the pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1 according to the present embodiment is not particularly limited, preferably 0% or more, and more preferably 0.1% or more. Here, the haze value in this specification shall be the value measured based on JISK7136:2000.

(3) Color

In the pressure-sensitive adhesive layer 11 in the present embodiment, the chromaticity a* defined by the CIE1976 L*a*b* colorimeter is preferably -5.0 to 5.0, particularly preferably -3.0 to 3.0,- It is more preferably 2.0 to 2.0. In addition, the pressure-sensitive adhesive layer 11 in the present embodiment preferably has a chromaticity b* defined by the CIE1976 L*a*b* colorimeter of -5.0 to 5.0, particularly preferably -3.0 to 3.0, It is more preferable that it is -2.0 to 2.0. When the chromaticity a* and the chromaticity b* are in the above range, the pressure-sensitive adhesive layer 11 becomes close to colorless and transparent, and is suitable for attaching a backlight.

Further, the color a* of the pressure-sensitive adhesive layer 11 after placing the pressure-sensitive adhesive sheet 1 according to the present embodiment under conditions of 50°C and 50% RH for 500 hours is preferably -5.0 to 5.0, and -3.0 to 3.0 It is especially preferable that it is, and it is more preferable that it is -2.0-2.0. Moreover, it is preferable that chromaticity b* is -5.0-5.0, it is especially preferable that it is -3.0-3.0, and it is more preferable that it is -2.0-2.0. When the chromaticity a* and chromaticity b* are within the above range, the pressure-sensitive adhesive layer 11 becomes close to colorless and transparent, even under heat-resistant conditions in which the heating state of the light emitting body contacting the pressure-sensitive adhesive layer 11 continues for a long time. As it becomes more favorable.

In addition, the color a* of the pressure-sensitive adhesive layer 11 after irradiating ultraviolet rays with an illuminance of 500 mW/m 2 for 500 hours with respect to the pressure-sensitive adhesive sheet 1 according to the present embodiment is preferably -5.0 to 5.0, and -3.0 to 3.0 It is especially preferable that it is, and it is more preferable that it is -2.0-2.0. Moreover, it is preferable that chromaticity b* is -5.0-5.0, it is especially preferable that it is -3.0-3.0, and it is more preferable that it is -2.0-2.0. When the chromaticity a* and chromaticity b* are within the above range, the pressure-sensitive adhesive layer 11 is close to colorless and transparent and has excellent light resistance even under conditions in which the light-emitting state of the light-emitting body contacting the pressure-sensitive adhesive layer 11 continues for a long time. It is more suitable for affixing a backlight.

In addition, the measurement method of chromaticity a* and chromaticity b* in this specification is as showing in the test example mentioned later.

(4) Adhesion

The adhesive strength of the pressure-sensitive adhesive sheet 1 according to the present embodiment at 23° C. to soda-lime glass is preferably 10 N/25 mm or more, more preferably 13 N/25 mm or more, and more preferably 15 N/25 mm or more as the lower limit. It is particularly preferred, and more preferably 26N/25 mm or more. When the lower limit value of the adhesive force is the above, the light-emitting body sealing property becomes more excellent. In addition, the adhesive strength of the pressure-sensitive adhesive sheet 1 according to the present embodiment at 23°C to soda-lime glass is preferably 100 N/25 mm or less, more preferably 80 N/25 mm or less, and more preferably 50 N/25 as the upper limit. It is particularly preferable to be less than or equal to mm. When the upper limit of the adhesive force is the above, good rework property is obtained.

Here, the adhesive force at 23°C in the present specification basically refers to the adhesive force measured by a 180-degree peeling method according to JIS Z0237:2009, but the measurement sample is 25 mm wide and 100 mm long, The measurement sample is affixed to the adherend, pressurized at 0.5 MPa, 50° C. for 20 minutes, then allowed to stand for 24 hours under conditions of normal pressure, 23° C., and 50% RH, and then measured at a peel rate of 300 mm/min. .

The adhesive strength of the pressure-sensitive adhesive sheet 1 according to the present embodiment at 50°C to soda-lime glass is preferably 2 N/25 mm or more, particularly preferably 4 N/25 mm or more, and 6 N/25 mm or more as the lower limit. It is more preferable. When the lower limit value of the adhesive force is the above, the sealing property of the luminous body under heat-resistant conditions becomes more excellent. Moreover, although the adhesive force in 50 degreeC with respect to soda-lime glass of the adhesive sheet 1 which concerns on this embodiment is not specifically limited, It is preferable that it is 100 N/25 mm or less, More preferably, it is 80 N/25 mm or less, It is particularly preferable that it is 50 N/25 mm or less.

Here, the adhesive force at 50°C in the present specification basically refers to the adhesive force measured by a 180-degree peeling method in accordance with JIS Z0237:2009, but the measurement sample is 25 mm wide and 100 mm long, The measurement sample is affixed to the adherend, pressed at 0.5 MPa, 50° C. for 20 minutes, then left for 6 hours under conditions of normal pressure, 50° C., and 50% RH, and measured at a peel rate of 300 mm/min. .

3. Preparation of adhesive sheet

As an example of production of the pressure-sensitive adhesive sheet 1, the coating solution of the pressure-sensitive adhesive composition P is applied to the release surface of one release sheet 12a (or 12b), and heat treatment is performed to crosslink the pressure-sensitive adhesive composition P and apply it. After forming the layer, the release surface of the other release sheet 12b (or 12a) is superimposed on the application layer. When a curing period is required, the curing period is set, and when the curing period is unnecessary, the coating layer becomes the pressure-sensitive adhesive layer 11 as it is. Thereby, the said adhesive sheet 1 is obtained. The conditions for heat treatment and curing are as described above.

As another manufacturing example of the pressure-sensitive adhesive sheet 1, the coating solution of the pressure-sensitive adhesive composition P is applied to the release surface of one release sheet 12a, and heat treatment is performed to heat-crosslink the pressure-sensitive adhesive composition P to form a coating layer. , A release sheet 12a with a coating layer is obtained. Moreover, the coating solution of the said adhesive composition P was apply|coated to the peeling surface of the other peeling sheet 12b, and heat-crosslinked the adhesive composition P by heat-processing, and formed a coating layer, and the release sheet with a coating layer (12b). And the release sheet 12a with an application layer and the release sheet 12b with an application layer are stuck so that both application layers may mutually contact. Here, a plurality of release sheets with a coating layer may be produced, and the coating layers may be bonded to a desired number. When the curing period is required, the curing period is set, and when the curing period is unnecessary, the above-described laminated coating layer becomes the pressure-sensitive adhesive layer 11. Thereby, the said adhesive sheet 1 is obtained. According to this production, even if the pressure-sensitive adhesive layer 11 is thick, it is possible to stably produce it.

As a method of 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.

[Backlight unit]

2 shows a backlight unit according to an embodiment of the present invention.

As shown in FIG. 2, the backlight unit 2 according to the present embodiment includes a backlight 20 provided with a plurality of light emitters 22 on one or two or more substrates 21 and the backlight 20, It is configured to include the pressure-sensitive adhesive layer 11 attached so that the light-emitting body 22 is sealed.

The pressure-sensitive adhesive layer 11 in the backlight unit 2 is the pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1 for attaching the backlight. The plurality of light-emitting bodies 22 are sealed without voids by the pressure-sensitive adhesive layer 11. Thereby, since the air layer and the voids are eliminated inside the display body to be obtained, it is possible to prevent deterioration of image quality due to reflection loss of light.

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

The substrates 21 may be formed integrally so that a plurality of light emitters 22 are integrated and mounted, or may be formed separately so that one light emitter 22 is mounted on one substrate 21. . When formed separately, each substrate 21 is usually fixed to a frame, a support, a casing or the like. In this embodiment, as shown in FIG. 2, it is preferable that the board|substrate 21 is formed integrally so that several light-emitting bodies 22 may be integrated and mounted.

A reflective layer may be formed on the surface of the substrate 21 on the pressure-sensitive adhesive layer 11 side, or a reflective member may be provided. Thereby, the luminance by the backlight 20 can be effectively improved. As the material of the reflective layer or reflective member, a known one can be employed.

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, and an inorganic electroluminescence light-emitting element. Among these, from the viewpoint of the sealing property by the pressure-sensitive adhesive layer 11, LEDs are preferable, and mini LEDs or micro LEDs are particularly preferable.

The thickness of the light-emitting body 22 is preferably 10 μm or more, more preferably 30 μm or more, particularly preferably 50 μm or more, and even more preferably 80 μm or more. In addition, the thickness of the light-emitting body 22 is preferably 300 μm or less, particularly preferably 150 μm or less, and further preferably 100 μm or less. With the pressure-sensitive adhesive layer 11 according to the present embodiment, even if the thickness of the light-emitting body 22 is within the above range, it is easy to seal the light-emitting body 22 without voids.

In addition, the width of the gap between the adjacent light-emitting bodies 22 is preferably 0.01 mm or more, particularly preferably 0.1 mm or more, and even more preferably 0.5 mm or more. In addition, the width of the gap is preferably 100 mm or less, more preferably 10 mm or less, particularly preferably 4 mm or less, and even more preferably 2 mm or less. With the pressure-sensitive adhesive layer 11 according to the present embodiment, even if the widths of the gaps of the light-emitting bodies 22 adjacent to each other are within the above range, the light-emitting bodies 22 are easily sealed without voids.

Although the shape of the light emitting body 22 is not particularly limited, it is usually a cuboid shape, a hemispherical shape, or the like. The size of the light emitter 22 is also not particularly limited, but from the viewpoint of the encapsulation property of the light emitter, it is preferable that one side or the diameter of the plane is 0.01 to 100 mm, more preferably 0.1 to 10 mm, and 0.2 to 5 mm. It is particularly preferable that it is 0.5 to 2 mm.

Here, a display body using the backlight unit 2 according to the present embodiment will be described. The type of the display body is not particularly limited as long as it is of a type using a backlight unit, but a liquid crystal display device is mainly exemplified.

3 shows a liquid crystal display device as an example in the present embodiment.

As shown in FIG. 3, the liquid crystal display device 3 according to the present embodiment includes the above-described backlight unit 2 and a diffusion member 31 laminated on the pressure-sensitive adhesive layer 11 of the backlight unit 2, It is comprised by the liquid crystal panel 32 laminated|stacked on the opposite side to the backlight unit 2 in the diffusion member 31. The backlight 20 in the liquid crystal display device 3 corresponds to a direct backlight.

The diffusion member 31 is a member that diffuses light emitted from the backlight unit 2, and the diffusion member 31 can effectively suppress the occurrence of luminance unevenness. As the diffusion member 31, a known one can be used, and for example, a diffusion plate, a diffusion film, or a combination thereof can be used. As for the liquid crystal panel 32, a well-known thing can be adopted.

Moreover, between the adhesive layer 11 and the diffusion member 31, between the diffusion member 31 and the liquid crystal panel 32, or on the surface opposite to the diffusion member 31 in the liquid crystal panel 32, , The desired optical member may be provided. Examples of such an optical member include a brightness enhancing film, a contrast enhancing film, a viewing angle compensation film, a transparent conductive film, a liquid crystal polymer film, a semi-transmissive reflective film, and a shatterproof film.

In order to manufacture the liquid crystal display device 3 according to the present embodiment, for 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 exposed. Is attached to the surface of the side where the light emitting body 22 of the backlight 20 is present.

Thereafter, the other release sheet 12b is peeled from the pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1, and the diffusion member 31 is pasted with the exposed pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1. Then, the diffusion member 31 and the liquid crystal panel 32 are pasted together using a desired adhesive sheet. Further, as another example, the bonding order of the backlight 20 and the diffusion member 31 may be changed.

In the liquid crystal display device 3, since the plurality of light-emitting bodies 22 in the backlight unit 2 are sealed without voids by the pressure-sensitive adhesive layer 11, degradation of image quality due to reflection loss of light is prevented. have. In addition, even if the liquid crystal display device 3 is placed under an endurance condition, for example, 85° C., 85% RH, 72 hours, floating or peeling at the interface between the pressure-sensitive adhesive layer 11 and the light-emitting body 22, etc. This occurrence is suppressed, and the sealing of the light-emitting body 22 by the pressure-sensitive adhesive layer 11 is maintained satisfactorily.

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 intended to include all design changes and equivalents falling within the technical scope of the present invention.

For example, either or both of the release sheets 12a and 12b in the adhesive sheet 1 may be omitted, and a desired optical member may be laminated in place of the release sheets 12a and/or 12b.

(Example)

Hereinafter, the present invention will be described more specifically by 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

60 parts by mass of 2-ethylhexyl acrylate, 10 parts by mass of isobornyl acrylate, 10 parts by mass of N-acryloyl morpholine, and 20 parts by mass of 2-hydroxyethyl acrylate were copolymerized by solution polymerization to obtain (meth)acrylic 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, the weight average molecular weight (Mw) was 500,000.

2. Preparation of adhesive composition

100 parts by mass of the (meth)acrylic acid ester polymer (A) (solid content equivalent; hereinafter referred to) obtained in step 1 above, and trimethylolpropane-modified tolylene diisocyanate as a crosslinking agent (B) (manufactured by Toyo Chem., product name ``BHS8515'') 0.15 The coating solution of the adhesive composition was obtained by mixing a mass part and 0.2 mass parts of 3-glycidoxypropyltrimethoxysilane as a silane coupling agent, sufficiently stirring, and diluting with methyl ethyl ketone.

Here, Table 1 shows each formulation (solid content conversion value) of the adhesive composition when (meth)acrylic acid ester polymer (A) is 100 parts by mass (solid content conversion value). In addition, the details, such as the symbol of Table 1, are as follows.

[(Meth)acrylic acid ester polymer (A)]

2EHA: 2-ethylhexyl acrylate

IBXA: isobornyl acrylate

ACMO: N-acryloyl morpholine

HEA: 2-hydroxyethyl acrylate

BA: n-butyl acrylate

AA: acrylic acid

MA: methyl acrylate

EA: ethyl acrylate

[Crosslinking system (B)]

TDI: trimethylolpropane-modified tolylene diisocyanate (manufactured by Toyo Chemisha, product name ``BHS8515'')

XDI: Trimethylolpropane-modified xylylene diisocyanate (manufactured by Soken Chemical Co., Ltd., product name "TD-75")

Epoxy: 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane (Mitsubishi Gas Chemical Co., Ltd. product name "TETRAD-C")

Al chelate: Aluminum trisacetylacetonate (manufactured by Soken Chemical Co., Ltd., product name "M-5A")

3. Preparation of adhesive sheet

The coating solution of the adhesive composition obtained in the above step 2 is coated with a knife coater on the peeling treatment surface of a medium peeling release sheet (trade name, manufactured by Lintec Corporation, product name ``SP-PET752150'') obtained by peeling one side of a polyethylene terephthalate film with a silicone-based release agent. Then, a heat-treatment was performed at 90°C for 1 minute to form a coating layer (thickness: about 50 µm), thereby producing a medium peeling release sheet with a coating layer.

On the other hand, the coating solution of the pressure-sensitive adhesive composition obtained in the above step 2 is a knife coater on a peeling treatment surface of a light peeling release sheet (trade name, manufactured by Lintec Corporation, product name ``SP-PET381130'') obtained by peeling one side of a polyethylene terephthalate film with a silicone-based release agent. After coating with, and heat-treated at 90° C. for 1 minute, a coating layer (thickness: about 50 μm) was formed to prepare a light peeling release sheet with a coating layer. Four light peeling release sheets with this coating layer were produced.

The surface on the coating layer side in the medium peeling release sheet with a coating layer obtained above and the surface on the coating layer side of the light peeling release sheet with a first coating layer obtained above are bonded together, and the coating layer having a total thickness of about 100 µm This obtained the 1st laminated body formed by sandwiching between a medium peeling type peeling sheet and a light peeling type peeling sheet.

Next, the surface of the coating layer side of the light peeling release sheet with a second coating layer is bonded to the exposed surface of the coating layer exposed by peeling the light peeling release sheet from the first laminate, and the total thickness is about 150 µm. A second layered product obtained by sandwiching the phosphorous coating layer between the medium peeling release sheet and the light peeling release sheet was obtained.

Next, the surface of the coating layer side of the light peeling release sheet with a third coating layer is bonded to the exposed surface of the coating layer exposed by peeling the light peeling release sheet from the second laminate, and the total thickness is about 200 μm. A phosphorous coating layer was sandwiched between the medium peeling release sheet and the light peeling release sheet to obtain a third laminate.

Subsequently, the surface of the coating layer side of the light peeling release sheet with a fourth coating layer was pasted to the exposed surface of the coating layer exposed by peeling the light peeling release sheet from the third laminate, and the total thickness was approximately 250 μm. A fourth layered product obtained by sandwiching the phosphorous coating layer between the medium peeling release sheet and the light peeling release sheet was obtained.

The fourth laminate was cured for 7 days under conditions of 23° C. and 50% RH to prepare a pressure-sensitive adhesive sheet comprising a composition of a medium peeling release sheet/adhesive layer (thickness: 250 μm)/light peeling release sheet.

In addition, the thickness of the said adhesive layer is a value measured using the static pressure thickness measuring instrument (product name "PG-02" manufactured by Techroxa) according to JIS K7130).

[Examples 2 to 6, Comparative Examples 1 to 3]

Type and proportion 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 crosslinking agent (B), and blending amount of the silane coupling agent And, the pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the thickness of the pressure-sensitive adhesive layer was changed as shown in Table 1. In addition, in Example 3 and Comparative Example 2, the thickness of the pressure-sensitive adhesive layer was changed by changing the number of layers of the coating layer formed on the light peeling release sheet.

Here, the weight average molecular weight (Mw) mentioned above is the weight average molecular weight of polystyrene conversion measured under the following conditions (GPC measurement) using gel permeation chromatography (GPC).

<Measurement conditions>

Measurement device: Dosoh Corporation, HLC-8320

GPC column (passed in the following order): manufactured by Tosoh Corporation

TSK gel superH-H

TSK gel superHM-H

TSK gel superH2000

Measurement solvent: tetrahydrofuran

Measurement temperature: 40℃

[Test Example 1] (Measurement of gel fraction)

The pressure-sensitive adhesive sheet obtained in Examples and Comparative Examples was cut to a size of 80 mm×80 mm, the pressure-sensitive adhesive layer was wrapped with a polyester mesh (mesh size 200), the mass was weighed with a precision balance, and the mesh alone was The mass of only the adhesive was calculated by subtracting the mass. Let the mass at this time be M1.

Next, the adhesive wrapped with the polyester mesh was immersed in ethyl acetate at room temperature (23°C) for 24 hours. Thereafter, the pressure-sensitive adhesive was taken out, air-dried for 24 hours in an environment of a temperature of 23°C and a relative humidity of 50%, 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 mesh alone was subtracted to calculate the mass of the adhesive alone. Let the mass at this time be M2. The gel fraction (%) is expressed as (M2/M1) x 100. Table 2 shows the results.

[Test Example 2] (Measurement of storage modulus)

The release sheet was peeled from the pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples, and a plurality of layers were laminated so that the pressure-sensitive adhesive layer had a thickness of 3 mm. A cylindrical body having a diameter of 8 mm (height of 3 mm) was punched from the obtained laminate of the pressure-sensitive adhesive layer, and this was used as a sample.

With respect to the sample, the storage elastic modulus (MPa) at 23°C and 50°C under the following conditions was performed by the torsional shearing method using a viscoelasticity measuring device (manufactured by Physica, product name "MCR300") according to JIS K7244-6. ). Table 2 shows the results.

Measurement frequency: 1Hz

Measurement temperature: 23℃, 50℃

[Test Example 3] (Measurement of adhesive force)

A polyethylene terephthalate (PET) film having a self-adhesive layer and a self-adhesive layer that peels off the light-peelable release sheet from the adhesive sheets obtained in Examples and Comparative Examples (Toyobosha, product name ``PET A4300'') , Thickness: 100 µm) was adhered to the self-adhesive layer to obtain a laminate of a release sheet/adhesive layer/PET film. The obtained laminate was cut into 25 mm width and 100 mm length, and used as a sample.

Under the environment of 23° C., 50% RH, the medium peeling release sheet was peeled from the sample, and the exposed adhesive layer was adhered to soda-lime glass (manufactured by Nippon Itara Glass Co., Ltd.), followed by an autoclave made by Kurihara Seisakujosha 0.5. Pressurized at MPa and 50°C for 20 minutes. And it was left for 24 hours under conditions of 23°C and 50% RH, or left for 6 hours under conditions of 50°C and 50% RH.

Thereafter, under the same conditions as described above (23° C., 50% RH/50° C., 50% RH), using a tensile tester (manufactured by Orientec, product name "Tensiron"), the peeling rate was 300 mm/min, The adhesive force (N/25 mm) at 23°C and 50°C was measured under conditions of a peeling angle of 180 degrees. Conditions other than those described herein were measured in accordance with JIS Z 0237:2009. Table 2 shows the results.

[Test Example 4] (Evaluation of purchaseability)

An adhesive sheet (made by Lintec Corporation, product name "MO-T015C") obtained by sandwiching an acrylic pressure-sensitive adhesive layer (thickness of 25 µm) with two release sheets was prepared, and one release sheet was peeled off. The exposed pressure-sensitive adhesive layer was adhered to a self-adhesive layer of a PET film having a self-adhesive layer (manufactured by Toyobosha, product name "PET A4300", thickness: 75 mu m) to obtain a laminate of release sheet/adhesive layer/PET film. The obtained laminate was cut into 1 mm width and 70 mm length to obtain an adhesive tape, and a plurality of these adhesive tapes were produced.

The plurality of adhesive tapes from which the other release sheet was peeled from the adhesive tape and the pressure-sensitive adhesive layer was exposed was 70 mm × 70 mm so that the gap between the adjacent adhesive tapes was 5 mm, 3 mm, or 1 mm. It was attached to a soda-lime glass plate (made by Nippon Itara Glass Co., Ltd.) of this size, and this was used as an adherend.

On the other hand, peeling the light peeling release sheet from the pressure-sensitive adhesive sheet obtained in Examples and Comparative Examples, the exposed pressure-sensitive adhesive layer, PET film having a self-adhesive layer (Toyobosha, product name "PET A4300", thickness: 50㎛) It adhered to the adhesive layer to obtain a laminate of a release sheet/adhesive layer/PET film. Then, this laminate was cut to a size of 70 mm×70 mm.

Under the environment of 23°C and 50% RH, the medium peeling release sheet was peeled from the laminate, and the pressure-sensitive adhesive layer was exposed. Then, the laminate was laminated to the adherend so that the pressure-sensitive adhesive layer covered each pressure-sensitive adhesive tape using a laminator (manufactured by Fuji Plastics, product name "LPD3214"), and this was used as a sample for evaluation.

The obtained evaluation sample was autoclaved for 30 minutes under conditions of 50°C and 0.5 MPa, and then left at normal pressure, 23°C, and 50% RH for 24 hours. First, in this state, the state of the interface between the adherend and the pressure-sensitive adhesive layer was observed, and the embedding property (before durability) was evaluated based on the following criteria. Table 2 shows the results.

◎: No lifting or peeling

○: There is no lifting or peeling, but air bubbles are generated.

×: lifting and peeling occurred

Next, the said sample for evaluation was stored for 72 hours at 85 degreeC and 85% RH moist heat conditions (durability test), and after that, embedding property (after durability) was evaluated like the above. Table 2 shows the results.

[Test Example 5] (Measurement of total light transmittance)

The light peeling release sheet was peeled from the pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples, and the exposed pressure-sensitive adhesive layer was adhered to glass, and this was used as a measurement sample. After the background measurement was performed on the glass, the medium peeling release sheet was peeled from the sample for measurement to expose the pressure-sensitive adhesive surface, and under a condition of 23° C., a haze meter (manufactured by Nippon Denshoku Kogyo Co., Ltd.) according to JIS K7361-1:1997. , Product name "NDH-5000") was used to measure the total light transmittance (duration; %). Table 3 shows the results.

Next, the sample for measurement was stored for 500 hours under a high temperature condition of 50°C and 50% RH (heat resistance test), and then the total light transmittance (after heat resistance test; %) was measured in the same manner as above. Table 3 shows the results.

On the other hand, the sample for the measurement was put into a light resistance tester (manufactured by Suga Chemical Co., Ltd., product name "ultraviolet fade meter U48", light source: carbon arc lamp), and ultraviolet rays (illuminance: 500 mW/m2) were 500 from the medium peeling release sheet side. Time was investigated. Then, the total light transmittance (after the light resistance test; %) was measured in the same manner as above. Table 3 shows the results.

[Test Example 6] (Measurement of haze value)

The light peeling type release sheet was peeled from the pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples, and the exposed pressure-sensitive adhesive layer was adhered to glass, and this was used as a measurement sample. After the background measurement was performed on the glass, the medium peeling release sheet was peeled from the sample for measurement to expose the pressure-sensitive adhesive surface, and under a condition of 23°C, a haze meter (manufactured by Nippon Denshoku Kogyo Co., Ltd.) under the conditions of JIS K7136:2000. Haze value (before durability; %) was measured using ``NDH-5000''). Table 3 shows the results.

Next, the sample for measurement was stored at a high temperature condition of 50°C and 50% RH for 500 hours (heat resistance test), and then, a haze value (after heat resistance test; %) was measured in the same manner as above. Table 3 shows the results.

On the other hand, the sample for the measurement was put into a light resistance tester (manufactured by Suga Chemical Co., Ltd., product name "ultraviolet fade meter U48", light source: carbon arc lamp), and ultraviolet rays (illuminance: 500 mW/m2) were 500 from the medium peeling release sheet side. Time was investigated. Then, haze value (after light test; %) was measured in the same manner as above. Table 3 shows the results.

[Test Example 7] (Measurement of L*a*b*)

About the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet obtained in Examples and Comparative Examples, the chromaticity a specified by the CIE1976 L*a*b* colorimeter, using a simultaneous metering spectrophotometer (manufactured by Nippon Denshoku Kogyo, product name "SQ2000") * And chromaticity b* (before durability) were measured. Table 3 shows the results.

Next, the pressure-sensitive adhesive sheet was stored for 500 hours at a high temperature condition of 50°C and 50% RH (heat resistance test), and then the chromaticity a* and chromaticity b* (after the heat resistance test) were measured in the same manner as above. Table 3 shows the results.

On the other hand, the pressure-sensitive adhesive sheet was put into a light resistance tester (manufactured by Suga Chemical Co., Ltd., product name "ultraviolet fade meter U48", light source: carbon arc lamp), and ultraviolet light (illuminance: 500 mW/m 2) was applied from the medium peeling release sheet for 500 hours. Investigated. Thereafter, chromaticity a* and chromaticity b* (after light resistance test) were measured in the same manner as above. Table 3 shows the results.

[Test Example 8] (Measurement of residual monomer amount)

0.02 g of the pressure-sensitive adhesive was isolated from the pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples, and the pressure-sensitive adhesive was placed in a vial having a capacity of 22 mL and held at 120°C for 30 minutes. Thereafter, the gas phase component in the vial was introduced into a gas chromatograph (Hewlett-Packard Co., product name "6890 type") using a head space sampler (manufactured by Parkin Elmer, product name "Turbo Matrix 40"), and component analysis was performed. In addition, HP-5 manufactured by Hewlett-Packard Co., Ltd. was used as the separation column. As a result, it was confirmed that the amount of residual monomer was less than 0.1% by mass in the adhesive of any example.

[Table 1]

[Table 2]

[Table 3]

As can be seen from Table 2, the pressure-sensitive adhesive sheet obtained in Examples was excellent in embedding properties both before and after the durability test. In addition, as can be seen from Table 3, the pressure-sensitive adhesive sheet obtained in the Examples had a high degree of colorless transparency before and after the durability test, the heat resistance test, and the light resistance test.

The adhesive sheet and backlight unit for attaching a backlight of the present invention can be suitably used, for example, in a liquid crystal display device using a direct backlight.

1: Adhesive sheet for attaching backlight
11: adhesive layer
12a, 12b: release sheet
2: Backlight unit
20: backlight
21: substrate
22: luminous body
3: liquid crystal display device
31: diffusion member
32: liquid crystal panel

Claims (6)

As a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer is attached to the backlight provided with a plurality of light-emitting body on a substrate, so that the light-emitting body is sealed,
The storage elastic modulus at 50°C of the pressure-sensitive adhesive layer is 0.001 MPa or more and 0.15 MPa or less,
The gel fraction of the adhesive constituting the adhesive layer is 10% or more and 75% or less,
The thickness of the pressure-sensitive adhesive layer, 110㎛ or more
Adhesive sheet for attaching a backlight, characterized in that. According to claim 1,
A pressure-sensitive adhesive sheet for attaching a backlight, characterized in that the storage elastic modulus at 23°C of the pressure-sensitive adhesive layer is 0.01 MPa or more and 0.20 MPa or less. According to claim 1,
The pressure-sensitive adhesive sheet for attaching a backlight, wherein the pressure-sensitive adhesive is an acrylic pressure-sensitive adhesive. According to claim 1,
Two release sheets,
The pressure-sensitive adhesive layer sandwiched by the release sheet so as to contact the release surface of the two release sheets
Adhesive sheet for attaching a backlight, characterized in that it comprises a. A backlight provided with a plurality of light emitters on one or two or more substrates,
The adhesive layer attached to the backlight so that the light-emitting body is sealed
A backlight unit having a,
The pressure-sensitive adhesive layer is the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet for attaching the backlight according to any one of claims 1 to 4.
A backlight unit, characterized in that. The method of claim 5,
The backlight unit, characterized in that the light-emitting body is a light-emitting diode.

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