JP2002285120A - Resin composition, double-side adhesive, reflecting member, lighting system and liquid crystal display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition and a double-side adhesive capable of strongly and stably adhering to a substrate having ruggedness, and free from peeling. SOLUTION: This resin composition comprises an acrylic polymer 11 and particles 12 having size capable of entering at least a part of the particles to a dent part of the adherend. The maximum diameter of the particles is preferably in the range of 10-90% of the minimum diameter of the dent part in a plane view to smoothly insert the resin composition into the dent part of the adherend through the particles 12. The resin composition preferably includes a photo curable compound, a vinyl compound and a photo initiator on the standpoint to enhance the adherence with the adherend. The double-sided adhesive member comprises a sticky layer 1 mainly comprising the prescribed resin composition or comprises the sticky layer 3, 4 mainly comprising the resin composition to at least a side of a substrate B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition used for bonding to an adherend having an uneven surface, and a double-sided adhesive member, a reflection member, a lighting device, and a liquid crystal display device using the same.

[0002]

2. Description of the Related Art An acrylic resin composition containing an acrylic polymer as a main component has excellent heat resistance, weather resistance, oil resistance, and excellent adhesive properties, and has been used as a pressure-sensitive adhesive. Widely used. For example, an acrylic resin composition has been applied to both sides of a support such as a polyethylene terephthalate (PET) tape and used as a double-sided adhesive tape.

[0003] This double-sided adhesive tape has a very strong and stable adhesive effect when bonding flat portions without irregularities of an adherend, but exerts the effect when bonding uneven portions. In some cases, it was not enough. For example, as shown in FIG. 10, a light source 72 is disposed on a side portion of a light guide 71 in which a prism portion 71P is integrally formed on an upper surface,
In the illumination device 7 of the liquid crystal display device in which the reflection sheet 73 is provided so as to go from the upper surface to the lower surface of the light guide 71 while covering the outer periphery of the light source 72, one end of the reflection sheet 73 is connected to the light guide 71. Is fixed with a double-sided adhesive tape T on the prism portion 71P formed on the upper surface of the substrate. When the lighting device 7 was subjected to a durability test, a problem that the reflection sheet T was peeled off from the light guide 71 frequently occurred. The cause of such inconvenience is that the adhesive area between the double-sided adhesive tape T and the prism portion 71P of the light guide is too small to ensure a sufficient adhesive force, and that the adhesive between the prism portion 71P and the double-sided adhesive tape T The intrusion of moisture from the formed space causes the adhesive layer to be hydrolyzed and the adhesive strength to be reduced.

In order to prevent such a double-sided adhesive tape from peeling off, an attempt has been made to increase the thickness of the pressure-sensitive adhesive layer made of an acrylic resin composition to increase the bonding surface with the prism portion, or to achieve a stronger bonding effect. Various studies such as an attempt to use a resin composition have been made up to now. However, it has not yet been achieved to effectively prevent the peeling of the adhesive tape from the prism portion.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been made in view of such conventional problems, and has a resin composition which adheres strongly and stably to an adherend having irregularities and does not peel off. It is an object of the present invention to provide an adhesive member.

Another object of the present invention is to provide a reflection member which can be strongly fixed to a light guide having an uneven surface.

It is a further object of the present invention to provide a lighting device and a liquid crystal display device in which a light guide having irregularities on its surface and a reflecting member are strongly fixed.

[0008]

According to the present invention, there is provided a resin composition used for bonding to an adherend having irregularities, wherein the resin composition has an acrylic polymer and a size which allows at least a part to enter a concave portion of the adherend. And a resin composition comprising:

Here, in order to push the resin composition into the concave portions of the adherend via the particles, the maximum diameter of the particles is preferably in the range of 10 to 90% of the minimum diameter of the concave portions of the adherend in plan view. .

From the viewpoint of further strengthening the adhesion to the adherend, it is desirable to further include a photocurable compound, a vinyl compound, and a photoreaction initiator.

Further, according to the present invention, there is provided a double-sided adhesive member provided with an adhesive layer containing the above resin composition as a main component.

Further, according to the present invention, there is provided a double-sided adhesive member characterized in that an adhesive layer containing the above resin composition as a main component is formed on at least one side of a support.

Here, from the viewpoint of preventing the adhesive layer from flowing out when the storage temperature is high, improving the releasability of the release liner, and improving the initial adhesiveness to the adherend, It is desirable to form an overcoat adhesive layer having a higher viscoelastic modulus than the adhesive layer.

According to the present invention, there is further provided a reflecting member for fixing at least one end to a light guide having an uneven surface, wherein the double-sided adhesive member is attached to a portion where the light guide is fixed. A reflective member is provided that is worn.

Further, according to the present invention, there is provided a light guide having an uneven surface, a light source, and a reflecting member having one end fixed to the uneven surface of the light guide and provided so as to cover the outer periphery of the light source. And wherein the unevenness on the surface of the light guide and the reflective member are bonded to each other with the double-sided adhesive member.

Further, according to the present invention, there is provided a liquid crystal display device comprising the above-mentioned illumination device and a liquid crystal display element.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have conducted intensive studies with the aim of obtaining a resin composition which can adhere strongly and stably even to an adherend having irregularities. The present inventors have found that the object can be achieved by incorporating the compound of the present invention, and have accomplished the present invention.

That is, a significant feature of the resin composition of the present invention is that the acrylic polymer contains particles that can at least partially enter the concave portions of the adherend. A conventional pressure-sensitive adhesive layer containing an acrylic polymer containing no particles as a main component is difficult to sufficiently penetrate deep into a concave portion due to its surface elasticity only by being pressed from the outside of the pressure-sensitive adhesive layer. Further, even if the adhesive layer can penetrate into the concave portion, it is due to the reversible elastic deformation of the adhesive layer, so that the adhesive layer tries to return to its original state, and it is difficult to secure a sufficient adhesive area stably after all. Was. On the other hand, in the pressure-sensitive adhesive layer containing the resin composition of the present invention as a main component, the force applied from the outside of the pressure-sensitive adhesive layer is applied to the bonding surface side of the pressure-sensitive adhesive layer through the particles, so that the pressure-sensitive adhesive layer is located deep inside the concave portion. Can be pushed into. In addition, once the adhesive layer has penetrated deep into the recess, the particles suppress the adhesive layer from trying to return to its original state.As a result, the deformation of the adhesive layer is close to irreversible plastic deformation, and the adhesive layer loses its original shape over time. Never return to For this reason, the unevenness of the adherend comes into contact with the adhesive layer without any gap, and the two adhere strongly and stably.

The shape and material of the particles used in the present invention are not particularly limited as long as a part of the particles can enter the concave portion of the adherend. In order to effectively transmit even to the adhesive surface of the layer, the shape is preferably a powder-granular shape, and more preferably a spherical shape and an elliptical cross-sectional shape. The material of the particles may be organic or inorganic. As an organic type, for example, polyolefin resin, epoxy resin, phenol resin,
Examples thereof include unsaturated polyester resins, acrylic resins, and polyimide resins. In order to obtain a preferable spherical shape, those produced by suspension polymerization or emulsion polymerization are desirable. On the other hand, as the inorganic type, for example, Au, Pt, Ag, C
u, Al, Fe, Ni, Sn, Ti, Pd and their alloys, metals such as oxides, nitrides and sulfides of these metals; glasses such as soda glass, lead glass and borosilicate glass; sulfates And inorganic salts such as chlorides, carbonates and nitrates; and silicon compounds such as silica. When heat resistance is required, ceramics such as oxides and nitrides can be preferably used.

The size of the particles to be used may be appropriately determined depending on the concave portion of the adherend, but it is recommended that the maximum diameter of the particle is in the range of 10 to 90% of the minimum diameter of the concave portion in plan view. If the maximum diameter of the particles is less than 10% of the minimum diameter of the concave portion in plan view, the force applied from the outside of the pressure-sensitive adhesive layer may not be able to be effectively transmitted to the adhesive surface side of the pressure-sensitive adhesive layer. If is larger than 90% of the minimum diameter of the concave portion in plan view, the adhesive layer may not be able to be sufficiently pushed into the concave portion because the particles cannot enter the depth of the concave portion. A more preferable particle size is such that the maximum diameter of the particle is in the range of 20 to 60% of the minimum diameter of the concave portion in plan view.
The absolute size of the particles is preferably about 1 to 50 μm. As shown in FIG. 3, the maximum diameter of the particle means the maximum width in the projected area of the particle, and the minimum diameter of the concave portion in plan view is the minimum when the surface having irregularities is viewed from directly above. Means width.

The content of the particles in the resin plastic material of the present invention may be appropriately determined based on the surface condition of the adherend and the type of the acrylic polymer to be used. According to the experimental results, the range of 0.1 to 15% by volume with respect to the resin composition is preferable. In FIG.
4 shows the relationship between the content of particles and the adhesive strength. The results of this experiment show that spherical resin having an average particle size of 30 μm was added to an acrylic polymer to form a resin composition, which was used as a 1.5 mm-wide P
It is applied on an ET film to form an adhesive layer having a thickness of 35 μm, and is adhered onto a light guide surface on which a prism portion having a pitch of 100 μm and a vertex angle of 90 ° is integrally formed, and is pulled using a predetermined measuring jig. It is a result when performing a 90 degree peeling test at a speed of 300 mm / min.

According to FIG. 4, although the adhesive strength tends to decrease as the content of the particles increases, the content of the particles is reduced to 0.1.
In the range of 1 to 10% by volume, the adhesive strength is 138 to 115.
(G / 1.5 mm), and the decrease is small.
However, when the content of the particles exceeds 10 vol%, the decrease in the adhesive strength becomes remarkable, and when the content is 30 vol%, 70% is obtained.
(G / 1.5mm). The adhesive force required for practical use is generally 50 (g / 1.5 mm), but the lower limit of the adhesive force is 100 (g / 1.5 mm) when the safety factor is doubled. The particle content at this time is about 15 vol% from FIG. Therefore, the above preferable range is shown as the content of the particles. A more preferred content is in the range of 0.1 to 10 vol%, and a still more preferred content is in the range of 0.1 to 1 vol%.

A microscopic study of the relationship between the content of such particles and the adhesive strength reveals that, in a resin composition containing 0.1 vol% of particles, particles per prism groove are about 0.1%.
There will be 37 particles, and finally one particle will be present in three prism grooves. This is the lower limit of the particle content. On the other hand, in the resin composition containing 10 vol% of particles, there are 27 particles per one prism groove. When this is converted into the average distance of the center of gravity, it is about 55
μm, considering that the particle size of the particles is 30 μm, it is understood that if the particles are further contained, the average distance to the center of gravity will be smaller than the particle size of the particles and the adhesive force of the resin composition will be reduced. You.

The acrylic polymer used in the present invention is a polymer or a copolymer obtained by using acrylate or methacrylate (hereinafter, both may be collectively referred to as “(meth) acrylate”) as a monomer. .
As such a monomer, an alkyl (meth) acrylate having 1 to 17 carbons is preferable, and specifically, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (Meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, pentyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n
-Octyl (meth) acrylate, isooctyl (meth) acrylate, lauryl (meth) acrylate, and the like, and these may be used alone or in combination of two or more. Among them, 2-ethylhexyl (meth) acrylate, n-butyl (meth) acrylate, and isobutyl (meth) acrylate are particularly preferable.

The above (meth) acrylate monomers include carboxyl groups, hydroxyl groups, epoxy groups,
It may be copolymerized with another functional monomer having a functional group such as a mercapto group. Functional monomers that can be used for copolymerization include (meth) acrylic acid,
Maleic acid, itaconic acid, carboxyl group-containing compounds such as crotonic acid, 2-hydroxyethyl acrylate,
Hydroxyl-containing compounds such as 2-hydroxypropyl acrylate and 2-hydroxyvinyl ether;
N-dimethylaminoethyl acrylate, N-tert
An amino group-containing compound such as -butylaminoethyl acrylate; an epoxy group-containing compound such as glycidyl (meth) acrylate;
More than one type can be used in combination. The copolymerization ratio of these monomers is preferably up to 30% by weight, more preferably up to 20% by weight, based on the (meth) acrylate.

When the acrylic polymer used in the present invention contains such a functional monomer as a copolymer component, it can be cured by a crosslinking agent. Examples of the crosslinking agent that can be used include conventionally known crosslinking agents. For example, tolylene diisocyanate, hexamethylene diisocyanate,
Polyfunctional isocyanate cross-linking agents such as trimethylolpropane-modified tolylene diisocyanate; polyfunctional epoxy cross-linking agents such as ethylene glycol diglycidyl ether and propylene glycol diglycidyl ether; N, N'-
Polyfunctional aziridine-based crosslinking agents such as hexamethylene-1,6-bis (1-aziridinecarboxamide) and trimethylolpropane-tri-β-aziridinylpropionate; metal chelate-based crosslinking agents such as aluminum acetylacetone complex Peroxides such as benzoyl peroxide; melamine-based cross-linking agents; and the like, and these may be used alone or in combination of two or more in accordance with the functional group of the acrylic polymer.

The method for producing the acrylic polymer used in the present invention is not particularly limited, and a conventionally known method can be used. For example, radical polymerization such as solution polymerization and emulsion polymerization can be mentioned. Here, as the polymerization initiator, a known polymerization initiator such as benzoyl peroxide or azobisisobutylnitrile can be used.

The molecular weight of the acrylic polymer is preferably in the range of 3,000 to 300,000 in number average molecular weight. When the molecular weight is smaller than 3,000, chemical changes such as hydrolysis are likely to occur, and the adhesive strength may be reduced. On the other hand, if the molecular weight is larger than 300,000, the viscosity becomes too high, and irreversible plastic deformation of the acrylic polymer may be difficult. A more preferred number average molecular weight is 5,000 to 10.
Range of ten thousand.

In order to enhance the adhesive strength of the resin composition of the present invention, a photocurable compound, a vinyl compound and a photoreaction initiator may be further contained in the resin composition of the present invention. According to such a configuration, after adhering the resin composition to the adherend, the resin composition is irradiated with light to form a structure in which the vinyl compound is crosslinked between the photocurable compounds, and is crosslinked and cured. The composition adheres more firmly to the adherend.

Examples of the photocurable compound that can be used here include a photopolymerizable unsaturated polyester and a compound having two or more acryloyl groups. Unsaturated polyesters are produced by a conventionally known method, specifically, saturated dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, adipic acid, sebacic acid; fumaric acid, maleic acid, itaconic acid, etc. Unsaturated dicarboxylic acids and their anhydrides as acid components, and ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, 1,2-
Butanediol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2-methyl-1,3-propanediol, 2,2-dimethyl-
1,3-propanediol, cyclohexane-1,4-
It is produced by reacting a polyhydric alcohol such as dimethanol, an ethylene oxide adduct of bisphenol A, and a propylene oxide adduct of bisphenol A as an alcohol component.

Examples of the compound having two or more acryloyl groups include epoxy acrylate resins, polyester acrylate resins, and urethane acrylate resins. Epoxy acrylate resin is
An epoxy (meth) acrylate obtained by reacting (meth) acrylic acid with an epoxy resin, having the following structural formula is exemplified. As the epoxy resin as a raw material, bisphenol A diglycidyl ether and its high molecular weight homologues, novolak-type polyglycidyl ethers and the like can be used. Such epoxy acrylate resins are commercially available as "RIPOXY SP".
Series (SP-1506, 1507, 1509, 2500, 4010, 9000) "(manufactured by Showa Polymer Co., Ltd.).

[0032]

Embedded image

Here, the polyester acrylate resin is a saturated or unsaturated polyester having a terminal carboxyl group obtained from a saturated dicarboxylic acid and / or an unsaturated dicarboxylic acid and a polyhydric alcohol, and typified by glycidyl (meth) acrylate. A saturated polyester or unsaturated polyester (meth) acrylate obtained by reacting an epoxy compound containing an α, β-unsaturated carboxylic acid ester group.

The urethane acrylate resin is a resin obtained by reacting a polyisocyanate with a polyol such as polyacryl polyol or hydroxyalkyl acrylate.

The degree of unsaturation of the photocurable compound may be appropriately determined according to the required adhesive strength, and generally, the unsaturated group equivalent (molecular weight per unsaturated group) is 100 to 1,000.
Is preferable. Those having an unsaturated group equivalent of less than 100 are usually difficult to synthesize, while those having an unsaturated group equivalent of more than 1,000 may not give a cured product having high hardness.

The content of the photocurable compound may be appropriately determined depending on the required adhesive strength and the like. For example, the range is preferably 1 to 30 parts by weight based on 100 parts by weight of the acrylic polymer. If the content of the photocurable compound is less than 1 part by weight, sufficient adhesive strength may not be obtained. On the other hand, when the content exceeds 30 parts by weight, it is necessary to increase the amount of the photoreaction initiator, which increases the production cost. Even if the photocurable compound is contained in an amount exceeding 30 parts by weight, the adhesive strength does not increase so much. A more preferred content is in the range of 1 to 10 parts by weight.

The vinyl compound used in the present invention includes
Styrene-based monomers such as styrene, chlorostyrene, vinyltoluene, and divinylbenzene; and polymerizable monomers having a (meth) acryloyl group such as methyl (meth) acrylate, ethyl (meth) acrylate, and ethylene glycol di (meth) acrylate. These can be used alone or in combination of two or more. The content of such a vinyl compound is in the range of 3 to 50 parts by weight based on 100 parts by weight of the photocurable compound. When the content of the vinyl compound is less than 3 parts by weight, photo-curing is difficult to occur, and sufficient adhesive strength may not be obtained. On the other hand, when the content exceeds 50 parts by weight, the initial adhesive strength to the adherend is reduced. This is because there is a possibility that it will decrease. A more preferred content is in the range of 10 to 30 parts by weight.

The photoinitiator used in the present invention is a compound which generates free radicals by the action of light. As the light for irradiation, ultraviolet light, microwave, infrared light, visible light, X-ray, γ-ray, or the like can be used, but ultraviolet light is preferable because high energy can be obtained. More preferably, there is ultraviolet light having a wavelength in the range of 200 to 400 nm. Such ultraviolet light is obtained from a light source such as a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, and a chemical lamp.

In the case of curing by irradiation with ultraviolet rays, the curing method varies depending on conditions such as the photoinitiator used, the type of light source for generating ultraviolet rays, and the distance between the light source and the coated surface. 1,000-4
A method of irradiating an ultraviolet ray of 000 angstroms for several seconds, at most for several tens of seconds, may be mentioned.

Examples of the photoreaction initiator include benzoin compounds such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether and benzyl dimethyl ketal; benzophenone, benzoyl benzoic acid, methyl benzoyl benzoate, 4-phenylbenzophenone, hydroxybenzophenone, acrylated benzophenone, 4-benzoyl-4′-methyldiphenylsulfide-3,3′-dimethyl-4-methoxybenzophenone, 4,4′-dimethylaminobenzophenone,
4,4′-diethylaminobenzophenone, 3,3 ′,
4,4'-tetra (t-butylperoxycarbonyl)
Benzophenone compounds such as benzophenone; 4-phenoxydichloroacetophenone, 4-t-butyl-dichloroacetophenone, 4-t-butyl-trichloroacetophenone, diethoxyacetophenone, 2-hydroxy-2-phenyl-1-phenylpropane-1- On, 1- (4-dodecylphenyl) -2-hydroxy-
2-methylpropan-1-one, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropane-
1-one, 4- (2-hydroxyethoxy) -phenyl- (2-hydroxy-2-propyl) ketone, 1-hydroxycyclohexylphenylketone, 2-methyl-1
Examples include acetophenone-based compounds such as-[4- (methylthio) phenyl] -2-morpholinopropane-1, and one or more of these photoreaction initiators can be used in combination.

Further, the content of the photoreaction initiator is preferably in the range of 10 to 50% by weight based on the photocurable compound. When the content of the photoreaction initiator is less than 10% by weight, the reaction may not be sufficiently performed. On the other hand, when the content exceeds 50% by weight, the physical properties of the cured resin composition may be deteriorated. It is. A more preferred content is in the range of 20 to 40% by weight.

Further, in order to further improve the curability of the resin composition of the present invention, a thermal radical generator may be blended if necessary. Examples of the thermal radical generator include sensitizers such as triethylamine, diethylamine, diethanolamine, ethanolamine, dimethylaminobenzoic acid, methyl dimethylaminobenzoate, thioxanthone, 2-isopropylthioxanthone, 2,4-diethylthioxanthone, and acetylacetone. Examples include benzoyl oxide and azobisisobutyronitrile.

In addition, various thermal polymerization inhibitors, leveling agents, thickeners, thickeners, thixotropy-imparting agents, antihalation agents, matting agents, ultraviolet rays, as long as the photocurability of the resin composition is not significantly reduced. An absorbent, a coloring pigment, a diluent, a filler, a reinforcing agent, a thermoplastic resin and the like may be blended.

When an adherend is adhered using the resin composition of the present invention, the resin composition of the present invention is applied to one or both of the adherends to be adhered to form an adhesive layer. Application of the resin composition to the adherend may be performed by a conventionally known method,
For example, coating methods such as brushing, dipping, spraying, curtain flow coater, gravure coat, roll coat, spin coat, and bar coat can be used. The thickness of the pressure-sensitive adhesive layer may be appropriately determined based on the difference in height of the unevenness of the adherend, the required pressure-sensitive adhesive strength, the size of the contained particles, and the like. In addition, when a photocurable compound is contained, it is necessary to consider light absorption. The thickness of the adhesive layer is generally 10 to 10
A range of 0 μm is preferred.

Then, the adherends are brought into contact with each other to press the contact portions. Then, the force applied from the outside is transmitted to the opposite side of the pressure-sensitive adhesive layer via the particles contained in the resin composition, and the pressure-sensitive adhesive layer penetrates deep into the concave portion even if the adherend has irregularities. As a result, the contact area between the pressure-sensitive adhesive layer and the adherend is greatly increased as compared with the related art, thereby significantly improving the adhesive strength. When the photocurable compound is contained in the pressure-sensitive adhesive layer, the photocurable compound is cured by irradiating the pressure-sensitive adhesive layer with light after bonding by pressing. This significantly increases the adhesive strength.

Next, the double-sided adhesive member of the present invention will be described.
You. A major feature of the present invention is the above-described resin composition of the present invention.
An object of the present invention is to provide an adhesive layer whose main component is a substance. This both sides
The adhesive member may be used with or without a support. Both sides without support
First, the adhesive member will be described. FIG. 1 shows both sides of the present invention.
FIG. 2 is a cross-sectional view illustrating an example of an adhesive member. Both sides of FIG.
The adhesive member is formed by coating the above resin composition on the release liner L.
The adhesive layer 1 is formed by fabric. Use here
As the release liner L, 40 to 150 g / m ^TwoOf degree
Paper, film and crepe processed on both sides with peelability
Apply paper or embossed film, and release agent.
Processed film, etc.
Cone processed paper is preferably used. In addition, the adhesive layer 1
The layer thickness depends on the height difference of the
What is necessary is just to determine suitably from the size of the particles contained, etc.
The range is usually about 10 to 100 μm.

Further, from the viewpoint of preventing the adhesive layer 1 from flowing out when the storage temperature is high, improving the releasability of the release liner L, and improving the initial adhesiveness to the adherend, FIG.
As shown in (b), it is desirable to form an overcoat adhesive layer 2 having a higher viscoelasticity than the adhesive layer 1 on the surface of the adhesive layer 1. The viscoelastic modulus of the overcoat pressure-sensitive adhesive layer 2 may be about 10 times higher than that of the pressure-sensitive adhesive layer 1, and is generally preferably in the range of 1 × 10 ⁵ to 10 × 10 ⁵ dyn / cm ² . Examples of the composition of the overcoat pressure-sensitive adhesive layer 2 include the above-mentioned acrylic polymer, that is, a polymer and a copolymer obtained by using (meth) acrylate as a monomer. The layer thickness of the overcoat pressure-sensitive adhesive layer may be within a range in which the above-mentioned effects can be obtained, and generally, a range of 1 to 10 μm is preferable.

When the double-sided adhesive member of the present invention is formed in a sheet shape, it is desirable to further form a release liner L on the uppermost surface as shown in FIG. 1C to protect the adhesive layer.

Such a double-sided adhesive member is manufactured by a conventionally known manufacturing method. As an example, first, a resin composition constituting the adhesive layer 1 is prepared. Next, the resin composition is applied on the release liner L. When the overcoat pressure-sensitive adhesive layer 2 is formed between the release liner L and the pressure-sensitive adhesive layer 1, the overcoat pressure-sensitive adhesive layer 2 made of an acrylic polymer or the like is applied before the resin composition is coated. Let dry. As a coating method, a conventionally known method such as a knife, a reverse roll coater, or an air knife coater can be used. Then, the formed adhesive layer 1 is dried and, if necessary, crosslinked and cured. Then, if necessary, an overcoat pressure-sensitive adhesive layer 2 is similarly formed on the pressure-sensitive adhesive layer 1, and a release liner L is laminated on the pressure-sensitive adhesive layer (or the overcoat pressure-sensitive adhesive layer) to form a sheet, or a release liner L is bonded. It is rolled up as it is without combining. The shape of the double-sided adhesive member is not particularly limited, and may be a sheet shape, a tape shape, or any other shape. In the case of a tape shape, it can be obtained by slitting the wound roll shape.

Next, a double-sided adhesive member using a support will be described. FIG. 2 is a sectional view showing an example of such a double-sided adhesive member. The double-sided pressure-sensitive adhesive member shown in FIG. 2A has first and second pressure-sensitive adhesive layers 3 and 4 formed on the lower and upper surfaces of a support B, and the first pressure-sensitive adhesive layer 3 is formed of the resin composition described above. The second pressure-sensitive adhesive layer 4 is made of a conventionally known pressure-sensitive pressure-sensitive adhesive, here an acrylic polymer. A release liner L is formed below the first adhesive layer 3. The double-sided adhesive member shown in this figure is suitably used when the bonded portion of one adherend has an uneven surface and the bonded portion of the other adherend has a flat surface. That is, the first adhesive layer 3 is adhered to the uneven surface side, and the second adhesive layer 4 is adhered to the flat surface side.

Further, from the viewpoint of preventing the first adhesive layer 3 from flowing out when the storage temperature is high, improving the releasability of the release liner L, and improving the initial adhesiveness to the adherend, FIG. As shown in (b), it is desirable to form an overcoat adhesive layer 2 having a higher viscoelastic modulus than the adhesive layer 3 on the lower surface of the first adhesive layer 3. The same overcoat pressure-sensitive adhesive layer 2 as described above can be used here.

When bonding the uneven surfaces of the adherend,
As shown in FIG. 3C, the first and second adhesive layers 3 and 4
May be formed from the above resin composition. Similarly, the overcoat pressure-sensitive adhesive layer 2 may be formed outside the first and second pressure-sensitive adhesive layers 3 and 4. In the case of the pressure-sensitive adhesive layer containing the resin composition as a main component, the thickness of the layer may be appropriately determined from various conditions in the same manner as described above, but is generally preferably in the range of 10 to 100 μm. When it is made of a pressure-sensitive adhesive, its layer thickness is not particularly limited, but is generally preferably in the range of 10 to 100 μm, and more preferably in the range of 15 to 50 μm.

As the support that can be used here, conventionally known supports can be mentioned, for example, paper, fibers, foams, cellulose films, polyacrylic resin films, polycarbonate films, polyester films, polyether films. Films such as films, polyvinyl chloride films, polyethylene films, and polypropylene films are exemplified. Among them, those having a light-transmitting property are preferable, and polyester films, polypropylene films, and polyvinyl chloride films are particularly preferably used.

Such a double-sided adhesive member using a support is manufactured by a conventionally known manufacturing method. In one embodiment, first, a resin composition constituting a first adhesive layer is prepared and applied on one surface of a support. In addition, the same method as the above method can be used here as a coating method. And
The formed first adhesive layer is dried and, if necessary, crosslinked and cured. Then, if necessary, an overcoat pressure-sensitive adhesive layer is similarly formed on the first pressure-sensitive adhesive layer, and then a release liner is laminated on the outermost layer (first pressure-sensitive adhesive layer or overcoat pressure-sensitive adhesive layer). Next, a second adhesive layer is applied on the other surface of the support directly or by a transfer method. And the second
After drying and curing the pressure-sensitive adhesive layer, it is wound up into a roll. In the case where the double-sided adhesive member is formed in a tape shape, the rolled material wound up is slit. Of course, the shape of the double-sided adhesive member is not particularly limited, and may be a sheet shape, a tape shape, or any other shape.

Next, a liquid crystal display device using the double-sided adhesive member of the present invention for bonding a light guide having irregularities on its surface to a reflective member will be described. FIG. 5 shows a schematic sectional view of the liquid crystal display device of the present invention. The liquid crystal display device 6 shown in FIG. 5 includes a housing 61 having a rectangular display opening on the upper surface, and a housing 61.
, A liquid crystal display element 62 provided on the illumination device 7 so as to coincide with the opening, and a diffusion sheet provided between the illumination device 7 and the liquid crystal display element 62. 63 and 65 and a prism sheet 64.
The illumination device 7 includes a prism portion (irregularities) 71 having a triangular cross section.
A light guide 71 having P integrally formed on its surface;
A fluorescent tube (light source) 72 disposed on the side of the
And a reflection plate (reflection member) 73 provided so as to surround in the circumferential direction and face the bottom surface of the light guide 71. In addition,
The prism section 71P may have a triangular cross section, a semicircular shape or a wavy shape, as a matter of course.

The light emitted from the fluorescent tube 72 enters the side surface of the light guide 71 directly or after being reflected by the reflection plate 73, and travels while being totally reflected in the light guide 71. Some of the light is scattered by a white dot pattern (or unevenness) formed on the back surface of the light guide 71 (both are not shown), and light leaking from the bottom surface of the light guide 71 is reflected by the reflection plate 73 to be reflected again. Used. Thus, the light guide 71 becomes a flat light source. The light emitted from the light guide 71 is provided with directivity by the diffusion sheets 63 and 65 and the prism sheet 64 and has high brightness. Then, the light enters the liquid crystal display element 62.

The process of bonding the reflector 73 to the light guide in the illumination device 7 will be described below. As shown in FIG. 6, first, the double-sided adhesive tape (double-sided adhesive member) shown in FIG. At this time, the second pressure-sensitive adhesive layer 4 is used for the bonding ((a) in the figure). Next, the release liner L of the double-sided adhesive tape adhered to the reflection plate 73 is peeled off, and the reflection plate 73 is opposed to a predetermined position of the prism portion 71P of the light guide (FIG. 2B). Then, the reflection plate 73 is pressed against the prism portion 71P (FIG. 3C). Thereby, the overcoat adhesive layer 2 and the first adhesive layer 3 of the double-sided adhesive tape penetrate deep into the groove of the prism portion 71P by the force transmitted through the particles 11. At this time, the adhesion with the prism portion 71P is exclusively by the overcoat adhesive layer 2. Then, the fluorescent tube 72
Is bent in such a manner as to surround in the circumferential direction and face the bottom surface of the light guide 71. This completes the physical assembly of the lighting device. Then, when the fluorescent tube 72 is turned on, the light from the fluorescent tube 72 passes through the light guide 71 (partially directly) and irradiates the first adhesive layer 3 to crosslink the first adhesive layer 3. It hardens ((d) in the figure). Thereby, the adhesive strength of the double-sided adhesive tape is significantly increased. The cross-linking curing is usually completed by light irradiation for several seconds, at most tens of seconds.

In the above-described embodiment, the sidelight system is used as the lighting device. However, the present invention is not limited to this, and may be a direct system.

The material of the reflection member of the present invention is not particularly limited as long as it reflects light. As the light source, conventionally known ones such as a fluorescent tube, a light emitting diode, and electroluminescence can be used, but a fluorescent tube is preferable from the viewpoint of luminance and power consumption. The liquid crystal display element includes a normally white type color TFT liquid crystal element, a color STN liquid crystal element, a transflective color TFT TFT liquid crystal element, a transflective color STN liquid crystal element, and a normally black type or monochrome type using the above-described driving method. Conventionally known ones such as those of the system type can be used.

[0060]

Example 1 100 parts by weight of an acrylic polymer, epoxy acrylate ("RIPOXY SP-15") as a photocurable compound
06 "), 1 part by weight of an acrylic monomer as a vinyl compound, 2 parts by weight of benzoin alkyl ether as a photoreaction initiator, a crosslinked polymer of divinylbenzene (average particle size 30 μm,“ Micropearl ”Sekisui Chemical (Manufactured by the company) was uniformly stirred and mixed using a stirrer to prepare a resin composition. As a support, a polyethylene terephthalate (PET) film having a thickness of 25 μm and a width of 1.5 mm was used, and the resin composition was applied on the upper surface thereof to form an adhesive layer having a thickness of 35 μm. Next, an acrylic polymer was applied thereon to form an overcoat pressure-sensitive adhesive layer having a thickness of 5 μm to obtain an adhesive tape of the present invention. Since the purpose was to measure the adhesiveness of the uneven portion, no adhesive layer was formed on the other surface of the support. The properties of this double-sided adhesive tape were measured by the following test methods. FIG. 7 shows the measurement results.

(Adhesion Test) Under the conditions of a temperature of 25 ° C. and a humidity of 60%, an adhesive tape was placed on the surface of a light guide on which a prism part having a pitch of 100 μm and an apex angle of 90 ° was integrally formed. The roller was reciprocated two times, and the adhesive tape was pressure-sensitively bonded. And in the case of the adhesive tape of the present invention, 1
After standing for 0 minutes, the fluorescent tube having the light wavelength shown in FIG. 8 was turned on for 5 minutes under the condition of a lamp current of 4 mArms to crosslink and cure the adhesive layer. The crosslinking reaction was mainly performed with light having a wavelength of 365 nm. Then, a 90-degree peel test was performed at a tensile speed of 300 mm / min using a predetermined measuring jig.

(Environmental test) After standing for 100 hours in an environment of a temperature of 40 ° C. and a humidity of 95%, the adhesive strength was measured by the test method described above.

(Durability test) In addition, one cycle of standing for 30 minutes in an environment of a temperature of -10 ° C. and then for 30 minutes in an environment of a temperature of 40 ° C. was repeated 100 times. Was used to measure the adhesive strength.

Comparative Example 1 An acrylic polymer was coated on the upper surface of a PET film having a thickness of 25 μm and a width of 1.5 mm as a support to form an adhesive layer having a thickness of 35 μm to form an adhesive tape. The properties of the adhesive tape were measured by the test method. The measurement results are shown in FIG.

The adhesive tape of Comparative Example 1 had an initial adhesive strength of 25 (g / 1.5 mm), which was comparable to that of a commercially available adhesive tape. However, the adhesive strength after an environmental test was 12 (g / 1.5 mm). 1.5m
m), which was halved compared to the initial adhesive strength, and peeled even when a slight external force was applied. In the durability test, the adhesive tape was peeled off without waiting for the end of the test. In contrast, in the double-sided adhesive tape of Example 1, the initial adhesive strength was 13
5 (g / 1.5 mm), which is 5 times as high as that of the adhesive tape of the comparative example, and after the environmental test, 130 (g / 1.5 mm), which is almost the same as the initial adhesive strength. Adhesive strength after durability test is 1
The value was as high as 20 (g / 1.5 mm).

(Actual Machine Test) For further confirmation, an actual machine test using an adhesive tape for a lighting device and a liquid crystal display device was performed. Example 1 and Comparative Example 1 as double-sided adhesive tapes
The other side of the support of the adhesive tape used in the above was coated with an acrylic polymer to further form an adhesive layer having a thickness of 20 μm. These double-sided adhesive tapes are referred to as Example 2 and Comparative Example 2 respectively. Using this double-sided adhesive tape, the reflection plate was adhered to the prism portion on the light guide, and the illumination device 7 and the liquid crystal display device 6 having the structure shown in FIG. 5 were assembled. Here, the diameter of the light source is 18 m.
m, fluorescent tube with a length of 72 mm, "E60L processed product" (manufactured by Kimoto Co., Ltd.) as a reflecting plate, and a prismatic light guide manufactured by Colcoat Co., Ltd. ), "Light up 1"
00MXE "(manufactured by Kimoto Corporation)," BEF2 "(manufactured by Sumitomo 3M) as a prism sheet," Light Up 100TL4 "(manufactured by Kimoto Corporation) as an upper diffusion sheet, and a normally white color T as a liquid crystal element.
An FT liquid crystal element was used.

The above-described durability test was performed on the lighting device and the liquid crystal display device manufactured using the double-sided adhesive tape of Example 2 and Comparative Example 2, and after the test, the luminance of the measurement points on the display section shown in FIG. 9 was measured. did. Note that a current of 2.
5 mArms was flowed. Table 1 shows the results.

[0068]

[Table 1]

According to Table 1, when the double-sided adhesive tape of Example 2 was used, the luminance of the backlight was 24 at the center.
00 cd / m ² , the highest, and four corners of 2000 to 2150
It was gently reduced to cd / m ^2, and the luminance unevenness (Max / Min) was 1.20, which was an ideal luminance distribution. On the other hand, when the double-sided adhesive tape of Comparative Example 2 was used, the reflection plate was separated from the light guide during the durability test. For this reason, light from the fluorescent tube leaked from the gap between the light guide and the reflection plate, and the luminance was greatly reduced. The brightness at the light guide starting end is 1700 and 1600 cd / m ² , and the center is 130.
0 cd / m ² , and 800 and 700 light guide terminations
cd / m ² , the luminance decreases as the distance from the fluorescent tube increases, the light is not effectively guided to the light guide, and the luminance unevenness is 2.43, which is a generally required luminance unevenness (1.3 or less). It was much larger than that.

The brightness of the liquid crystal display device using the above-mentioned lighting device was also improved when the double-sided adhesive tape of Example 2 was used.
The brightness of the display unit is the highest at 200 cd / m ^2, and the four corners are 1
The luminance was gently reduced to 67 to 179 cd / m ^2, and the luminance unevenness was 1.20, which was an ideal luminance distribution. In contrast, when the double-sided adhesive tape of Comparative Example 2 was used,
The luminance was greatly reduced and the luminance unevenness was 2.45, which was not practical.

[0071]

According to the resin composition of the present invention, an acrylic polymer and particles having a size at least partially entering the concave portion of the adherend are included, so that an externally applied force is applied to the adherend. To the bonding surface through the particles. As a result, the bonding area is increased, and the substrate is strongly and stably bonded to an adherend having irregularities and does not peel off.

When the maximum diameter of the particles is in the range of 10 to 90% of the minimum diameter of the concave portion of the adherend in plan view, the resin composition can be more smoothly pushed into the concave portion of the adherent via the particles.

Further, when a photocurable compound, a vinyl compound and a photoreaction initiator are further contained, the adhesion to the adherend can be further enhanced by the photocuring reaction.

Since the double-sided adhesive member of the present invention is provided with the pressure-sensitive adhesive layer containing the above-mentioned resin composition as a main component, the same effect as that of the above-mentioned resin composition, that is, even if the adherend has unevenness, It can be stably bonded. This effect can be similarly obtained even with a double-sided adhesive member having a support.

In the reflecting member of the present invention, since the double-sided adhesive member is adhered to the fixing portion with the light guide, even if the light guide has irregularities such as a prism on the surface, it is strongly fixed. It does not peel off.

Further, in the lighting device and the liquid crystal display device of the present invention, since the irregularities on the surface of the light guide and the reflective member are bonded by the double-sided adhesive member, the reflective member does not peel off from the surface of the light guide. .

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a double-sided adhesive member according to claim 4;

FIG. 2 is a sectional view showing an example of a double-sided adhesive member according to claim 5;

FIG. 3 is a perspective view showing a maximum diameter of a particle and a minimum diameter of a concave portion in a plan view.

FIG. 4 is a diagram showing the relationship between the content of particles and adhesive strength.

FIG. 5 is a cross-sectional view illustrating an example of the liquid crystal display device of the present invention.

FIG. 6 is a view showing a process of bonding a reflection plate to a light guide.

FIG. 7 is a diagram showing measurement results of an example.

FIG. 8 is a wavelength distribution diagram of a fluorescent tube.

FIG. 9 is a plan view showing a measurement position of luminance.

FIG. 10 is a partial sectional view showing a conventional lighting device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 adhesive layer 2 overcoat adhesive layer 3 first adhesive layer 4 second adhesive layer 6 liquid crystal display device 7 lighting device B support L release liner 62 liquid crystal display element 71 light guide 72 fluorescent tube (light source) 73 reflector (Reflective member)

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) C09J 7/02 C09J 7/02 Z 4J040 F21V 8/00 601 F21V 8/00 601A 5G435 601G 601F 601C G02F 1/13357 G02F 1 / 13357 G09F 9/00 336 G09F 9/00 336J // F21Y 103: 00 F21Y 103: 00 F term (reference) 2H091 FA23Z FA41Z FC18 FD15 FD23 GA17 LA17 4J004 AA10 AA17 AA18 AB01 AB07 CE01 EA05 4J011 AA03 PA04 PA04 PA08 PA09 PA15 PA64 PA69 PA85 PA86 PA88 PA97 PB06 PB22 PB40 PC02 QA03 QA08 QA13 QA19 QB12 QB20 QB24 RA03 SA01 SA21 SA31 UA01 VA01 WA06 4J026 AA44 AA45 AA76 BA05 BA07 BA27 BA28 DB05 DB06 FA05 GA08 AB10 AB05 AB08 AB10 AB05 AB24 AB25 AE01 AG01 BA05 BA07 BA18 BA20 CA03 CA10 CA12 CA15 CA16 CA19 CB10 CC03 CC05 CD09 4J040 DF001 ED112 FA042 FA262 FA272 FA292 JA08 JB09 KA03 KA13 KA15 5G435 AA08 BB12 BB15 EE27 FF03 FF06 GG 24 KK05

Claims (9)

[Claims] 1. A resin composition used for bonding to an adherend having irregularities, comprising: an acrylic polymer; and particles having a size such that at least a part thereof can enter a concave portion of the adherend. Resin composition. 2. A resin composition wherein the maximum diameter of the particles is in the range of 10 to 90% of the minimum diameter of the concave portion of the adherend in plan view. 3. The resin composition according to claim 1, further comprising a photocurable compound, a vinyl compound, and a photoreaction initiator. 4. A double-sided adhesive member provided with an adhesive layer containing the resin composition according to claim 1 as a main component. 5. A double-sided adhesive member, wherein an adhesive layer containing the resin composition according to claim 1 as a main component is formed on at least one side of a support. 6. The double-sided adhesive member according to claim 4, wherein an overcoat adhesive layer having a higher viscoelastic modulus than the adhesive layer is formed on the surface of the adhesive layer. 7. A double-sided adhesive according to any one of claims 4 to 6, further comprising a reflecting member for fixing at least one end of the light guide to the light guide having irregularities on the surface, wherein the light guide is fixed to the light guide. A reflection member, wherein the member is attached. 8. A light guide having irregularities on its surface, a light source,
A lighting device comprising: a reflecting member having one end fixed to the unevenness of the light guide surface and provided so as to cover an outer periphery of the light source, wherein the unevenness on the light guide surface and the reflecting member are provided. Items 4 to 6
A lighting device characterized by being bonded by the double-sided bonding member according to any one of the above. 9. A liquid crystal display device comprising the lighting device according to claim 8 and a liquid crystal display element.