KR101744980B1 - Adhesive composition for a backlight unit, a backlight unit and a liquid crystal display device - Google Patents

Abstract

The present invention relates to a pressure-sensitive adhesive composition for a backlight unit, a backlight unit and a liquid crystal display. The pressure-sensitive adhesive composition for a backlight unit according to the present invention can provide a backlight unit and a liquid crystal display device free from yellowing and whitening even under severe conditions such as high temperature and / or high humidity by controlling the color coordinate of the pressure- can do.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-sensitive adhesive composition for a backlight unit, a backlight unit and a liquid crystal display device,

The present invention relates to a pressure-sensitive adhesive composition for a backlight unit, a backlight unit, and a liquid crystal display device.

As the information society has developed in recent years, demands for display devices have been increasing in various forms. Of these, LCDs are excellent in image quality, can be made lighter and thinner, and have a low power consumption. .

However, the LCD itself can not emit light, so an external light source is required to realize a high-quality image. Therefore, the structure of the LCD is configured to further include a backlight unit as a light source of the liquid crystal display panel in addition to the liquid crystal display panel, and a high-quality light source is uniformly supplied to the liquid crystal display panel by the backlight unit.

Such a backlight is divided into an edge-lighting type and a direct-lighting type backlight unit, depending on the manner in which the light source is disposed. The side-type backlight unit includes one or a pair of lamps disposed on one side of the light- Or a structure in which two or two pairs of lamps are disposed on both side portions of the light guide plate, and the direct type backlight unit has a structure in which several lamps are disposed under the optical sheet. Among these, the side-type backlight unit is mainly used for LCDs of portable communication devices and the like requiring thinness due to its relatively thin thickness. The direct-type backlight unit is used for LCDs such as notebooks and TV monitors, .

In the case of a direct-type backlight unit, a PCB (printed circuit board) is generally used. A reflector disposed on the PCB; A light source disposed on the reflection plate; And a diffusion plate disposed on the light source, wherein LEDs are widely used as the light source. In particular, when an LED is used as a light source, a pressure-sensitive adhesive composition for embedding the LED may be coated on the LED substrate to fix the LED.

However, yellowing or clouding may occur during curing of the LED-embedding pressure-sensitive adhesive composition. Further, in severe conditions such as high temperature and / or high humidity conditions, occurrence of yellowing or clouding may occur more frequently. As described above, when yellowing or clouding occurs after the pressure-sensitive adhesive composition for LED embedding is cured, the light transmittance of the backlight unit is deteriorated.

Therefore, it is necessary to develop a pressure-sensitive adhesive composition for LED embedding which does not cause yellowing and cloudiness under severe conditions.

An object of the present invention is to provide a pressure-sensitive adhesive composition for a backlight unit, a backlight unit and a liquid crystal display device.

The present invention provides, as means for solving the above problems, an acrylic resin; Multifunctional crosslinking agents; And an antioxidant, wherein the pressure-sensitive adhesive composition for a backlight unit satisfies the following general formula (1).

[Formula 1]

? B = | B _i - B _l | / | B _i | × 100? 3.5%

In the general formula 1, B _i Is immediately after to produce the specimen by coating the adhesive composition between two plastic films, L * a * b * denotes the initial color coordinate b * value measured using a color difference meter, B _l is the specimen 80 ℃ and The color coordinate b * value measured using an L * a * b * colorimeter after being left under constant temperature and humidity conditions of 90% RH for 24 hours.

As another means for solving the above-mentioned problems, the present invention provides a semiconductor device comprising: a substrate; At least one light source formed on the substrate; And a pressure-sensitive adhesive layer containing a cured product of the pressure-sensitive adhesive composition for a backlight unit according to the present invention, which encapsulates the light source.

As another means for solving the above problems, the present invention provides a backlight unit according to the present invention; And a liquid crystal display panel formed on the backlight unit.

The pressure-sensitive adhesive composition for a backlight unit according to the present invention can provide a backlight unit and a liquid crystal display device free from yellowing and whitening even under severe conditions such as high temperature and / or high humidity by controlling the color coordinate of the pressure- can do.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a view showing a cross section of a specimen for measuring a rate of change (? B) of a color coordinate b * value;
2 is a view showing a cross-sectional view of a specimen for measuring the penetration distance.
3 is a view showing a specimen for measuring the highest heat generating temperature.
4 is a view showing a specimen for measuring the thickness deviation of the pressure-sensitive adhesive layer.
5 is a sectional view of a backlight unit according to one aspect of the present invention.
6 is a sectional view of a backlight unit according to another aspect of the present invention.
7 is a sectional view of a backlight unit according to another embodiment of the present invention.
8 is a sectional view of a backlight unit according to another aspect of the present invention.
9 is a sectional view of a liquid crystal display device according to an aspect of the present invention.

The present invention relates to an acrylic resin composition, Multifunctional crosslinking agents; And an antioxidant, wherein the pressure-sensitive adhesive composition for a backlight unit satisfies the following general formula (1).

[Formula 1]

? B = | B _i - B _l | / | B _i | × 100? 3.5%

In the general formula 1, B _i Is immediately after to produce the specimen by coating the adhesive composition between two plastic films, L * a * b * denotes the initial color coordinate b * value measured using a color difference meter, B _l is the specimen 80 ℃ and The color coordinate b * value measured using an L * a * b * colorimeter after being left under constant temperature and humidity conditions of 90% RH for 24 hours.

Hereinafter, the pressure-sensitive adhesive composition for a backlight unit of the present invention will be described in detail.

The pressure-sensitive adhesive composition of the present invention comprises an acrylic resin; Multifunctional crosslinking agents; And the antioxidant. In the pressure-sensitive adhesive composition of the present invention and the specimen made of the PET film, the rate of change (? B) of the color coordinate b * measured under specific conditions satisfies the condition of the general formula (1). That is, in the present invention, the specimen may have a rate of change (B) of the color coordinate b * of 3.5% or less, preferably 3% or less, more preferably 1% or less.

In the present invention, the lower limit of the rate of change (? B) of the color coordinate b * value is not particularly limited, and is preferably as close as 0%. As the rate of change (? B) of the color coordinate b * is low, the color coordinate does not change, and the pressure-sensitive adhesive composition maintains transparency, so that it can be applied to a backlight unit or a liquid crystal display device and exhibit excellent light transmittance.

The color coordinate b * value of the present invention can be measured using an L * a * b * colorimeter. In general, a colorimeter is a device for measuring the color of an object, and various types exist. The L * a * b * colorimeter is defined by the International Lighting Committee (CIE) (X, y, z) in a three-dimensional uniform color space consisting of a Y-axis and a Z-axis, and is now standardized globally because it shows a very close difference to the eye. The color coordinate corresponding to the X axis represents a red / green series as a color coordinate a * and is represented by -120 to +120 as a numerical value. The closer the color coordinate is to +120, the more red is displayed. The color coordinate corresponding to the Y axis represents a yellow / blue system as a color coordinate b *, and is represented by -120 to +120 as a numerical value. The closer to +120, the more yellowish the color coordinate and the closer to -120 the blue color. The values of all the color coordinates a * and b * are 0 in the state of zero saturation and gray means that the larger the absolute value of the product of the color coordinate a * and the color coordinate b *, the higher the chroma. The chromaticity coordinate corresponding to the Z axis is a chromaticity coordinate L *, a chromaticity coordinate indicating the brightness. Numerical values are represented by 0 to 100, 0 represents black (minimum brightness), and 100 represents white (maximum brightness).

In the present invention, the rate of change (B) of the color coordinate b * of the specimen can be measured by measuring the initial color coordinate b * of the specimen and the color coordinate b * of the latter color and assigning the values to the general formula 1 .

Specifically, FIG. 1 is a view showing a cross-sectional view of a specimen for measuring a rate of change (ΔB) of a color coordinate b * value prepared by coating a pressure-sensitive adhesive composition according to the present invention between two polyethylene terephthalate (PET) films.

As shown in FIG. 1, the pressure-sensitive adhesive composition 11 according to the present invention was coated on a plastic film 12 having a size of 5 cm × 5 cm (width × length) using a bar coater to a thickness of 0.3 mm to 3.0 mm Thereafter, a plastic film 12 having a size of 5 cm × 5 cm (width × length) is attached on the pressure-sensitive adhesive composition to prepare a test piece 10 for measuring the rate of change of the color coordinate b * value.

Immediately after preparing the specimen as shown in FIG. 1, the initial color coordinate b * is measured using an L * a * b * colorimeter. Thereafter, the sample is stored in a constant temperature and humidity room at 80 ° C. and 90% relative humidity (RH) for 24 hours, and then the color coordinate b * is measured using an L * a * b * colorimeter. The change rate (? B) of the color coordinate b * value can be measured by substituting the initial color coordinate b * and the later color coordinate b * into the above-described general formula (1).

In the present invention, occurrence of yellowing and opacity can be prevented by controlling the rate of change (B) of the color coordinate b * value according to the pressure-sensitive adhesive composition to 3.5% or less, thereby providing the backlight unit with a pressure- can do.

The pressure-sensitive adhesive composition for a backlight unit of the present invention may further satisfy the conditions of the following general formula (2).

[Formula 2]

X ₁ <1 mm

In the formula 2, X ₁ is _of 10kg In the following, the temperature of the specimen produced by laminate a plastic film on the cured product of the pressure-sensitive adhesive composition 60 ℃ curing after coating the pressure-sensitive adhesive composition on a substrate formed with a light source And the oozing distance of the pressure-sensitive adhesive composition exuding to the side of the specimen measured by pressing for 5 minutes by weight.

The pressure-sensitive adhesive composition of the present invention and the test piece made of the substrate can satisfy the condition of the general formula 2 by measuring the oozing distance X ₁ under specific conditions. That is, in the present invention, the specimen may have a penetration distance of less than 1 mm, preferably 0.5 mm or less, and more preferably 0.1 mm or less.

In the present invention, the lower limit of the penetration distance is not particularly limited, and the closer to 0 mm, the better. As the penetration distance is smaller, it can be applied to a backlight unit or a liquid crystal display device and exhibit an excellent effect.

In the present invention, the penetration distance can be measured using a vernier caliper.

Specifically, FIG. 2 is a sectional view of a specimen for measuring an exudation distance, which is prepared by coating a pressure-sensitive adhesive composition according to the present invention on a substrate on which a light source is formed.

2, a light source (LED) 22 having a thickness of 1.2 mm is disposed on a substrate 21 having a size of 10 cm × 10 cm (width × length), and the light source (LED) The pressure-sensitive adhesive composition 23 according to the present invention was coated on the substrate 21 to a thickness of 1.5 mm, irradiated with ultraviolet light of 600 mW / cm ^{2 in} intensity and 150 mJ / cm ² in intensity for 10 minutes using a high pressure mercury lamp And then a plastic film 24 having a size of 10 cm × 10 cm (width × length) is laminated to produce a specimen 20 for measuring the penetration distance. Then, the exudation distance of the specimen 20 to 50 ℃ pressure-sensitive adhesive composition 23 is pushed for churro fifth of 25 _of 10kg, seeping through the side of the specimen 20 at a temperature of (X ₁ ) Is measured using a vernier caliper.

In the present invention, by controlling the penetration distance of the pressure-sensitive adhesive composition to be less than 1 mm, it is possible to provide excellent effects when applied to a backlight unit.

As the acrylic resin contained in the pressure-sensitive adhesive composition in the present invention, for example, a polymer of a monomer mixture containing a (meth) acrylic acid ester monomer and a crosslinkable monomer may be used. In this case, May be a crosslinkable monomer composed of a silyl group-containing monomer.

As used herein, the term "crosslinkable monomer comprising a hydroxyl group-containing monomer" means that the crosslinkable monomer contained in the monomer mixture contains only a hydroxyl group-containing monomer among the crosslinkable monomers conventionally used in the pressure sensitive adhesive field it means. That is, when a carboxyl group-containing monomer or a nitrogen-containing monomer or the like is used as the crosslinkable monomer, it is excluded from the scope of the term.

In particular, it is preferable that the acrylic resin of the present invention does not contain a carboxyl group as a crosslinkable functional group. For example, as the monomer constituting the acrylic resin, it is preferable not to use a monomer containing a carboxyl group such as acrylic acid. Since the carboxyl group is a functional group mainly used for a pressure-sensitive adhesive because it is a functional group capable of imparting a high glass transition temperature and an adhesive force to the pressure-sensitive adhesive, the present inventors have found that a resin having a carboxyl group is present in the pressure- When applied to a backlight unit or the like, it was found that the pressure-sensitive adhesive could cause yellowing or clouding.

In the present invention, the kind of the (meth) acrylic acid ester monomer is not particularly limited and may be, for example, alkyl (meth) acrylate. In this case, if the alkyl group contained in the monomer is excessively long, the cohesive force of the cured product is lowered, and the glass transition temperature and the tackiness may be difficult to control. Therefore, the alkyl group having 1 to 14 carbon atoms, preferably 1 to 8 carbon atoms Alkyl (meth) acrylate can be used. Examples of such monomers include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n- (Meth) acrylate, sec-butyl (meth) acrylate, pentyl (meth) acrylate, 2-ethylhexyl (Meth) acrylate, isobonyl (meth) acrylate, isobonyl (meth) acrylate or isononyl (meth) acrylate. In the present invention, one or more of the above can be used.

The crosslinkable monomer contained in the monomer mixture in the present invention means a monomer which simultaneously contains a polymerizable functional group (e.g., carbon-carbon double bond) and a crosslinkable functional group in the molecular structure, and as described above, as the crosslinkable functional group It is preferable that the crosslinkable monomer is constituted only by a hydroxyl group-containing monomer containing a hydroxyl group. In this case, the kind of the hydroxyl group-containing monomer which can be used is not particularly limited, and examples thereof include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (Meth) acrylate, 2-hydroxypropyleneglycol (meth) acrylate, 2-hydroxypropyleneglycol (meth) And mixtures thereof.

In the present invention, the hydroxyl group-containing monomer may be contained in an amount of 15 to 40 parts by weight, preferably 20 to 30 parts by weight based on 100 parts by weight of the acrylic resin. If the content of the hydroxyl group-containing monomer in the acrylic resin of the present invention is less than 15 parts by weight, yellowing or clouding may occur. If the content is more than 40 parts by weight, the color coordinate b * of the cured product of the pressure- There is a risk that yellowing may occur due to an increase in the value.

Unless specifically stated otherwise herein, the unit "parts by weight" means "parts by weight".

In the present invention, a method for producing an acrylic resin by polymerizing a monomer mixture containing the above-mentioned respective components is not particularly limited. In the present invention, general polymerization methods such as solution polymerization, photopolymerization, bulk polymerization, suspension polymerization or emulsion polymerization can be used, for example.

The pressure-sensitive adhesive composition for a backlight unit of the present invention may include a multifunctional crosslinking agent together with the acrylic resin, and physical properties such as cohesion and adhesion properties of the cured product may be controlled according to the amount of the multifunctional crosslinking agent.

The type of the multifunctional crosslinking agent that can be used in the present invention is not particularly limited, but it may contain a double bond in the molecule and preferably have a molecular weight of 1000 or less. In the present invention, for example, a polyfunctional (meth) acrylate can be used as the polyfunctional crosslinking agent, and the polyfunctional (meth) acrylate means a polymerizable compound having two or more (meth) acrylate residues in the molecule do.

Specific examples of the polyfunctional (meth) acrylate include hexanediol di (meth) acrylate, trimethylolpropane trioxyethyl di (meth) acrylate, alkylene glycol di (meth) acrylate, (Meth) acrylate, dicyclopentenyloxyethyl di (meth) acrylate, neopentyl glycol di (meth) acrylate, dicyclopentenyl di (meth) acrylate, (Meth) acrylate, dipentaerythritol hexa di (meth) acrylate, trimethylol propane tri (meth) acrylate, and pentaerythritol tri (meth) acrylate.

In the pressure-sensitive adhesive composition for a backlight unit of the present invention, the polyfunctional crosslinking agent may be contained in an amount of 0.9 to 10 parts by weight, preferably 1 to 3 parts by weight, based on 100 parts by weight of the acrylic resin. If the content of the polyfunctional crosslinking agent is less than 0.9 parts by weight, the cohesive force of the hardened shoe may deteriorate and the adhesive may seep out. If the content of the polyfunctional crosslinking agent exceeds 10 parts by weight, the glass transition temperature of the cured product becomes high, And there is a possibility that the adhesive strength is lowered.

The pressure-sensitive adhesive composition of the present invention may further include an antioxidant to prevent yellowing or clouding even under severe conditions such as high temperature and / or high humidity conditions.

The kind of the antioxidant that can be used in the present invention is not particularly limited and includes, for example, one selected from the group consisting of phenolic amides, phenolic esters, hindered amines, polymeric hindered phenols, hindered phosphites, Or more. Specific examples of the antioxidant include N, N'-hexamethylenebis (3,5-di- (tert) -butyl-4-hydroxyhydrocinnamamide) (Irganox 1098, Ciba Specialty Chemicals) Phenolic amides such as tetrakis- (methylene- (3,5-di- (tert-butyl-4-hydrocinnamate)) methane (Irganox 1010, Ciba Specialty Chemicals); Benzene amine (ex Irganox 5057, Ciba Specialty Chemicals); Phenol-based esters such as ethylene bis (oxyethylene) bis- (3- (5-tert-butyl-4-hydroxy-m-tolyl) -propionate (Iraganox 245, Ciba Specialty Chemicals) , 3,5-triazine-2,4,6-triamine, N, N '' '- [ , 2,6,6-pentamethyl-4-piperidinyl) amino] -1,3,5-triazin-2-yl] imino] -3,1-propanediyl]] bis [ (Chimassorb 119 FL, manufactured by Ciba Specialty Chemicals), 1 &quot; , 6-hexanediamine, N, N'-bis (2,2,6,6-tetramethyl-4-piperidinel) with 2,4,6-trichloro-1,3,5- - polymer, reaction products of N-butyl-1-butanamine with N-butyl-2,2,6,6-tetramethyl-4-piperidinamine (Chimassorb 2020, Ciba Specialty Chemicals) Polymeric membranes such as hindered amines, 2,2,4-trimethyl-1,2-dihydroxyquinoline (Ultranox 254, CROMPTONSA) (2,4-di-tert-butylphenyl) pentaerythritol diphosphite (Ultranox 626, chromium phthalate), tris (2,4-di- (Irgafos 168, Ciba Specialty Chemicals Inc.), 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid (Fiberstab PA6, Ciba Specialty Chemicals Inc.) Fight, etc., but the present invention is not limited thereto.

In the pressure-sensitive adhesive composition for a backlight unit of the present invention, the antioxidant may be contained in an amount of 2.2 to 30 parts by weight, preferably 2.5 to 12 parts by weight, based on 100 parts by weight of the acrylic resin. If the content of the antioxidant is less than 2.2 parts by weight, the effect of addition of the antioxidant may be insufficient. If the content of the antioxidant is more than 30 parts by weight, there is a possibility that phase separation occurs between the cured product of the pressure- sensitive adhesive composition and the antioxidant.

The pressure-sensitive adhesive composition for a backlight unit of the present invention comprises the above acrylic resin; Multifunctional crosslinking agents; And a photoinitiator together with an antioxidant.

As described above, the acrylic resin; Multifunctional crosslinking agents; The pressure-sensitive adhesive composition for a backlight unit of the present invention comprising an antioxidant and a photoinitiator may satisfy the condition of the following general formula (3).

[Formula 3]

X ₂ &amp;le; 80 DEG C

In the general formula (3), X ₂ represents the maximum heat-generating temperature that can be reached while curing the ultraviolet-curable adhesive composition.

The pressure-sensitive adhesive composition of the present invention comprises an acrylic resin; Multifunctional crosslinking agents; Antioxidants; And a photoinitiator, and the maximum exothermic temperature measured at a specific curing condition may satisfy the condition of the general formula (3).

That is, in the pressure-sensitive adhesive composition of the present invention, the ultraviolet ray having an illuminance of 600 mW / cm ² and a light intensity of 150 mJ / cm ² is irradiated for 0.5 to 30 minutes using a high-pressure mercury lamp, May be 80 占 폚 or lower, preferably 70 占 폚 or lower, and more preferably 20 占 폚 to 65 占 폚.

The term &quot; maximum heat generation temperature &quot; used in the present invention means a temperature at which the temperature of the pressure-sensitive adhesive composition of the present invention is directly fixed to the pressure-sensitive adhesive composition from the start to the end of curing, Lt; / RTI &gt;

In the present invention, the maximum exothermic temperature of the pressure-sensitive adhesive composition is obtained by preparing the pressure-sensitive adhesive composition of the present invention, coating the pressure-sensitive adhesive composition so that the thickness of the pressure-sensitive adhesive composition is 0.5 mm to 3.0 mm on a substrate having a thickness of 0.5 mm to 2.0 mm After sealing the LED, it can be measured using a thermometer by irradiating with a high-pressure mercury lamp at an illuminance of 600 mW / cm ² and a light intensity of 150 mJ / cm ² for 0.5 to 30 minutes.

Specifically, FIG. 3 is a schematic diagram showing a method for measuring a maximum exothermic temperature that can be reached during curing of a pressure-sensitive adhesive composition in the present invention. 3, a light source (LED) 22 having a thickness of 0.5 mm to 2.0 mm is disposed on a substrate 21, and a light source (LED) 22 is disposed on the substrate 21 to seal the light source The pressure-sensitive adhesive composition 23 according to the present invention is coated to prepare a specimen 30 for measuring the highest exothermic temperature. Thereafter, at the time of curing the pressure-sensitive adhesive composition (23), the thermometer (31) attached to the fixing device (32) was fixed at a height so as to directly contact the pressure-sensitive adhesive composition. Using the ultraviolet rays The temperature change is observed while curing for 0.5 to 30 minutes, and the temperature of the peak is measured. The temperature of the measured peak corresponds to the highest heat temperature to be measured in the present invention.

In the present invention, it is possible to minimize the thickness deviation of the pressure-sensitive adhesive layer that seals the light source (LED) in the backlight unit by controlling the maximum exothermic temperature that can be reached during the curing of the pressure- So that uniform luminance can be supplied.

Further, an acrylic resin; Multifunctional crosslinking agents; The pressure-sensitive adhesive composition for a backlight unit of the present invention comprising an antioxidant and a photoinitiator may satisfy the condition of the following general formula (4).

[Formula 4]

Y = Y ₁ - Y ₂ ? 200 μm

In the general formula (4), Y ₁ is coated on a substrate having a light source of 0.5 mm to 2.0 mm in thickness so as to have a thickness of 0.5 to 3.0 mm, sealing the light source, irradiating ultraviolet rays to cure the adhesive, Y ₂ is the thickness of the pressure-sensitive adhesive layer measured at any other point, and Y ₁ is larger than Y ₂ .

Generally, the pressure-sensitive adhesive layer for sealing the light source of the backlight unit is required to have transparency and uniform thickness due to its optical characteristics. When the thickness variation of the pressure-sensitive adhesive layer occurs, a partial luminance difference is generated thereby, and uniform brightness can not be provided. Therefore, in order for the backlight unit to provide uniform brightness, the thickness deviation of the pressure-sensitive adhesive layer should be minimized, and the thickness deviation measured at any two points of the pressure-sensitive adhesive layer should be 200 占 퐉 or less.

FIG. 4 is a view showing a specimen for measuring the thickness deviation of a pressure-sensitive adhesive layer which is a cured product of the pressure-sensitive adhesive composition of the present invention.

4, a light source (LED) 22 having a thickness of 0.5 mm to 2.0 mm is disposed on a substrate 21, and a light source (LED) The pressure-sensitive adhesive composition according to the present invention is coated to a thickness of 0.5 mm to 3.0 mm and cured by irradiating ultraviolet rays at an illuminance of 600 mW / cm ² and a light intensity of 150 mJ / cm ² for 0.5 to 30 minutes using a high pressure mercury lamp By forming the pressure-sensitive adhesive layer (41), a test piece (40) for measuring the thickness deviation of the pressure-sensitive adhesive layer is produced. In order to allow the pressure-sensitive adhesive composition to completely seal the light source in the specimen, the thickness of the pressure-sensitive adhesive composition may be more than the thickness of the light source. After the specimen is prepared as described above, the thickness of the pressure-sensitive adhesive layer at any one point, specifically, the thickness of the pressure-sensitive adhesive layer at the upper end portion of the LED, Y ₁ and the pressure- the thickness of the layer, specifically, it is possible to measure the thickness of Y ₂ of the pressure-sensitive adhesive layer between the LED and the LED part to calculate a thickness deviation (△ Y) of the pressure-sensitive adhesive layer.

In the present invention, the thickness deviation (? Y) of the pressure-sensitive adhesive layer may be 200 占 퐉, preferably 150 占 퐉 or less, more preferably 100 占 퐉 or less.

In the present invention, the lower limit of the thickness deviation (? Y) of the pressure-sensitive adhesive layer is not particularly limited. That is, in the present invention, as the value of the thickness deviation (? Y) approaches 0 mm, the pressure-sensitive adhesive composition can be applied to the backlight unit and exhibit an excellent effect.

In the present invention, by controlling the thickness deviation of the pressure-sensitive adhesive layer as a cured product of the pressure-sensitive adhesive composition to be 200 占 퐉 or less, it is possible to suppress the occurrence of a luminance difference and to provide a uniform luminance.

The type of photoinitiator that can be used in the present invention is not particularly limited as long as it can generate radicals by light irradiation to initiate polymerization reaction. Specific examples of the photopolymerization initiator that can be used in the present invention include a benzoin-based initiator, a hydroxyketone-based initiator, and an amino ketone-based initiator. More specifically, benzoin, benzoin methyl ether, benzoin ethyl ether, Benzoin isopropyl ether, benzoin n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy- Methyl-1 - [4- (methylthio) phenyl] -2-morpholino (2-hydroxyphenyl) 2-propyl) ketone, benzophenone, 4,4'-diethylaminobenzophenone, dichlorobenzophenone, 2 (2-hydroxyethoxy) Methyl anthraquinone, 2-ethyl anthraquinone, 2-t-butyl anthraquinone, 2-amino anthraquinone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, benzyl dimethyl ketal, acetophenone dimethyl ketal and oligo [2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propanone], and the like, but are not limited thereto. In the present invention, one or more of the above can be used.

As used herein, the term &quot; light irradiation &quot; means irradiation of an electromagnetic wave that can cause a polymerization reaction by affecting a photoinitiator or a polymerizable compound. In the above, electromagnetic waves include microwaves, infrared rays, ultraviolet rays, X- Of course, it is used generically to mean particle beams such as alpha-particle beams, proton beams, neutron beams, and electron beams.

In the pressure-sensitive adhesive composition for a backlight unit of the present invention, the degree of polymerization of the pressure-sensitive adhesive may be controlled depending on the amount of the photoinitiator. For example, 0.01 part by weight to 0.7 part by weight, preferably 0.1 part by weight, 0.5 part by weight.

If the content of the photoinitiator is less than 0.01 part by weight, the effect of addition of the photoinitiator may be insufficient. When the content of the photoinitiator exceeds 0.7 parts by weight, excessive polymerization reaction proceeds in the pressure-sensitive adhesive composition, There is a fear of causing a thickness variation of the pressure-sensitive adhesive layer as a cured product.

The pressure-sensitive adhesive composition for a backlight unit of the present invention may further include a silane coupling agent in addition to the above-mentioned components. Such a coupling agent improves the adhesion between the cured product and the adherend, in particular, the glass substrate and the adhesion stability, and can improve the heat resistance and moisture resistance. In addition, when properly added, the silane coupling agent not only improves adhesion reliability of the cured product under high temperature and / or high humidity, but also improves late adhesion.

Examples of the silane-based coupling agent usable in the present invention include, for example,? -Glycidoxypropyltrimethoxysilane,? -Glycidoxypropylmethyldiethoxysilane,? -Glycidoxypropyltriethoxy Silane, 3-mercaptopropyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane,? -Methacryloxypropyltrimethoxysilane,? -Methacryloxypropyltriethoxysilane,? -Aminopropyl But is not limited to, one or more of the following: trimethoxysilane,? -Aminopropyltriethoxysilane, 3-isocyanatepropyltriethoxysilane,? -Acetoacetatetrimethyltrimethoxysilane, and the like .

In the pressure-sensitive adhesive composition for a backlight unit of the present invention, the silane coupling agent may be included in an amount of 0.005 part by weight to 5 parts by weight based on 100 parts by weight of the acrylic resin. If the content of the silane coupling agent is less than 0.005 parts by weight, the effect of addition of the coupling agent may be insignificant. If the content of the silane coupling agent exceeds 5 parts by weight, bubbles or peeling phenomenon may occur due to the residue of the coupling agent not participating in the bonding There is a fear that the durability reliability is deteriorated.

The pressure-sensitive adhesive composition of the present invention may further comprise a tackifying resin that conforms to the properties of the pressure-sensitive adhesive, in order to control the tacking performance.

The kind of the tackifier resin that can be used in the present invention is not particularly limited and includes, for example, a hydrocarbon resin or a hydrogenated product thereof; Rosin resin or hydrogenated product thereof; Rosin ester resins or hydrogenated products thereof; Terpene resin or hydrogenated product thereof; Terpene phenol resin or hydrogenated product thereof; A polymerized rosin resin, a polymerized rosin ester resin and the like, or a mixture of two or more thereof.

In the pressure-sensitive adhesive composition for a backlight unit of the present invention, the tackifier resin may be contained in an amount of 1 part by weight to 100 parts by weight based on 100 parts by weight of the acrylic resin. If the content of the tackifier resin is less than 1 part by weight, the effect of adding the tackifier resin may be insignificant. If the content of the tackifier resin is more than 100 parts by weight, the compatibility or the cohesive force improving effect is lowered, .

The pressure-sensitive adhesive composition for a backlight unit of the present invention may further contain at least one additive selected from the group consisting of an epoxy resin, a crosslinking agent, a UV stabilizer, a colorant, a reinforcing agent, a filler, a defoamer, a surfactant and a plasticizer, . &Lt; / RTI &gt;

The present invention also provides a semiconductor device comprising: a substrate; At least one light source formed on the substrate; And a backlight unit having the pressure-sensitive adhesive layer containing the cured product of the pressure-sensitive adhesive composition according to the present invention, which encapsulates the light source.

5 is a sectional view of a backlight unit 50 according to an aspect of the present invention. As shown in Fig. 5, the backlight unit 50 of the present invention includes a substrate 51; At least one light source (52) formed on the substrate (51); And a pressure-sensitive adhesive layer (53) containing the cured product of the pressure-sensitive adhesive composition of the present invention, which encapsulates the light source (52).

In the present invention, the type of the substrate is not particularly limited, but may be a printed circuit board.

The method of forming the light source on the substrate in the present invention is not particularly limited, and may be performed by means generally known in this field.

As described above, the method of curing the pressure-sensitive adhesive composition of the present invention after the light source is formed on the substrate and producing the pressure-sensitive adhesive layer to seal the light source is not particularly limited. In the present invention, for example, a pressure-sensitive adhesive layer can be prepared by applying the above-mentioned pressure-sensitive adhesive composition or a coating liquid prepared by using the same to a substrate on which the light source is formed by using a conventional means such as a bar coater, have.

In the present invention, the curing process is preferably performed after sufficiently removing the bubble-inducing component such as volatile components or reaction residues contained in the pressure-sensitive adhesive composition or coating solution. The crosslinking density or molecular weight of the pressure-sensitive adhesive is too low to lower the modulus of elasticity, and it is possible to prevent the problem that the bubbles existing in the pressure-sensitive interface increase at high temperature to form a scattering body therein.

In addition, the method of curing the pressure-sensitive adhesive composition or the coating liquid is not particularly limited. For example, the curing process may be performed by applying ultraviolet (UV) to the coating layer or aging under a predetermined condition.

The type of the light source included in the backlight unit of the present invention is not particularly limited, and any light emitting device can be used without limitation. As the light source of the present invention, for example, a cold cathode fluorescent lamp, an external electrode fluorescent lamp, an LED or the like may be used, but preferably an LED capable of division driving can be used.

When an LED is used as the light source of the present invention, the thickness of the LED may be 0.5 mm to 2.0 mm, preferably 1.0 mm to 1.2 mm.

In the backlight unit of the present invention, the pressure-sensitive adhesive layer formed as described above may be more than the thickness of the light source (LED) since it is required to seal the light source (LED). The thickness of the pressure-sensitive adhesive layer may be 0.5 mm to 3.0 mm, preferably 1.0 mm to 1.6 mm, in order to maintain a proper distance between a diffusion plate and a light source (LED) to be described later.

The backlight unit of the present invention may further include a reflector formed between the substrate and the light source so that the light emitted from the light source is reflected and emitted toward the liquid crystal display panel formed on the backlight unit.

6, the backlight unit 60 of the present invention includes a reflection plate (not shown) formed between the substrate 51 and the light source 52, 61). &Lt; / RTI &gt;

The specific kind of the reflector used in the present invention is not particularly limited and can be used without limitation as long as it can reflect light. For example, in the present invention, a silver reflector, an aluminum reflector, or a multi-layered polymer may be used as the reflector, but the present invention is not limited thereto.

In the present invention, the thickness of the reflection plate is not particularly limited and may be suitably selected in accordance with the application to be used.

The backlight unit of the present invention may further include a diffuser plate formed on the pressure-sensitive adhesive layer that seals the light source so that a uniform luminance can be maintained even at an interval between the light source and the light source.

7 is a sectional view of a backlight unit according to another embodiment of the present invention. Referring to FIG. 7, the backlight unit 70 of the present invention includes a pressure-sensitive adhesive layer (not shown) 53 may be further included.

The diffusing plate of the present invention can be configured to have various haze characteristics according to the light uniformity, and the haze value of the diffusing plate at this time can be obtained by using a light diffusing component (not shown) such as a bead Or by forming a fine pattern (not shown) on the lower surface of the diffuser plate. That is, the light diffusion component such as beads can prevent the light from being partially concentrated by dispersing the light incident on the diffusion plate, and the light scattering angle can be adjusted according to the shape of the fine pattern. As a result, the diffusing plate can disperse the light so that the light is partially concentrated, for example, light is concentrated only at the upper end of the light source, and light is hardly reached at the upper portion between the light source and the light source .

Further, the backlight unit of the present invention may further include a plurality of optical sheets on top of the diffusion plate. The plurality of optical sheets may include a diffusion sheet and a light collecting sheet.

8 is a sectional view of a backlight unit according to another embodiment of the present invention. As shown in FIG. 8, the backlight unit 80 of the present invention includes a diffusion sheet 81 formed on a diffusion plate 71 And a light-condensing sheet 82 formed on the diffusion sheet 81. The light-

In the present invention, the diffusion sheet may be positioned on the top of the diffusion plate. The diffusion sheet may disperse the light incident through the diffusion plate and adjust the direction of the light to proceed toward the light collecting sheet. And can condense the light that has passed through and is condensed in the direction of the liquid crystal display panel. Accordingly, the light passing through the light condensing sheet can be almost vertically propagated to the liquid crystal display panel.

The present invention also relates to a backlight unit according to the above-mentioned present invention; And a liquid crystal display panel formed on the backlight unit.

9 is a sectional view of a liquid crystal display device according to an embodiment of the present invention.

9, the liquid crystal display 100 of the present invention may include a liquid crystal display panel 90 stacked on top of a backlight unit 80. As shown in FIG. The backlight unit 80 includes a substrate 51; A reflection plate (61) formed on the substrate (51); At least one light source (52) formed on the reflection plate (61); A pressure sensitive adhesive layer 53 sealing the light source 52 and containing a cured product of the pressure sensitive adhesive composition according to the present invention; A diffusion plate (71) formed on the pressure sensitive adhesive layer (53); A diffusion sheet 81 formed on the diffusion plate 71; And a light collecting sheet 82 formed on the diffusion sheet 81.

Although not shown in the present invention, the liquid crystal display panel includes, for example, a liquid crystal layer; A first substrate facing each other with the liquid crystal layer interposed therebetween; And a second substrate.

In the structure shown in Fig. 9 attached, the constitution and the formation method of other constituents except for the pressure-sensitive adhesive layer containing the cured product of the pressure-sensitive adhesive composition of the present invention are not particularly limited, and general components and means in this field are not limited .

[ Example ]

Hereinafter, the present invention will be described in more detail with reference to the following examples and comparative examples, but the scope of the present invention is not limited by the following examples.

< Color coordinates  For measuring rate of change of b * value>

Manufacturing example  1. Preparation of acrylic resin (A)

80 parts by weight of ethylhexyl acrylate (EHA) was added to a 1 L reactor equipped with a cooling device so that nitrogen gas was refluxed and temperature was easily controlled. 20 parts by weight of 2-hydroxyethyl acrylate (HEA) was added, and ethyl acetate (EAc) was added as a solvent. Subsequently, nitrogen gas was purged for about 1 hour to remove oxygen, and the mixture was homogenized while maintaining the temperature at 62 DEG C. Then, azobisisobutyronitrile diluted to 50% concentration in ethyl acetate as a reaction initiator (AIBN) were added thereto. Subsequently, the mixture was reacted to prepare an acrylic resin (A) having a weight average molecular weight of 500,000.

Example  One

Preparation of pressure-sensitive adhesive composition

1 part by weight of a multifunctional crosslinking agent (hexanediol diacrylate) and 3 parts by weight of an antioxidant (Irganox 1010, manufactured by Ciba Specialty Chemicals) were added to 100 parts by weight of the acrylic resin (A) to prepare a pressure- This was used to prepare a coating solution.

Color coordinates  Preparation of specimen for measuring rate of change of b * value

A polyethylene terephthalate film having a size of 5 cm × 5 cm (width × length) was coated with the coating solution of the pressure-sensitive adhesive composition prepared above in a thickness of 2.0 mm using a bar coater. Then, a 5 cm × 5 cm ), To prepare a specimen. &Lt; tb &gt;&lt; TABLE &gt;

Example  2 and Comparative Example  1, 2

A specimen was prepared in the same manner as in Example 1, except that the composition of the pressure-sensitive adhesive composition was changed as shown in Table 1 below.

Example Comparative Example One 2 One 2 Acrylic resin (A) Content 100 100 100 100 Multifunctional Cross-linking agent  content One One One One Antioxidant content 3 4.5 One 2 Content Unit: parts by weight
Multifunctional crosslinking agent: hexanediol diacrylate
Antioxidant: Irganox 1010, Ciba Specialty Chemicals,

The physical properties of the specimens for measuring the change rate of the b * value of the color coordinates prepared in Examples and Comparative Examples were measured by the following methods.

One. Color coordinates  Measuring rate of change of b * value

The initial color coordinates b * values measured using an L * a * b * colorimeter (Labscan XE, Hauter Lab) immediately after the preparation of the specimens were measured for B _i , And when the specimen is stored in a constant temperature and humidity chamber (at a temperature of 80 ° C. and a relative humidity of 90%) for 24 hours, and the measured b * value of the latter color coordinate of the specimen is B ₁ ,

The change rate (? B) of the color coordinate b * value was measured by substituting into the following general formula (1).

[Formula 1]

? B = | B _i - B _l | / | B _i | × 100? 3.5%

2. Yellow  And Cloudy  Measurement of occurrence

After measuring the rate of change (? B) of the color coordinate b *, the specimen was visually observed for the occurrence of yellowing or opacity and evaluated according to the following criteria.

X: No yellowing or clouding occurred

△: Yellowing or clouding occurred very little

○: a large amount of yellowing or clouding occurs

The results of the above physical property measurement are summarized in Table 2 below.

Example Comparative Example One 2 One 2 △ B 0.5% 0.3% 4.4% 4.2% Yellow  Occur × × ○ △ Cloudiness  Occur × × × ×

As can be seen from the results of Table 2, in the case of the specimens according to Examples 1 and 2 of the present invention, by controlling the rate of change (B) of the color coordinate b * to 3.5% or less, I did. However, in the case of the specimens according to Comparative Examples 1 and 2, the rate of change (? B) of the color coordinate b * exceeded 3.5%, causing yellowing.

That is, in the case of the embodiment using the pressure-sensitive adhesive composition for a backlight unit according to the present invention, the rate of change (? B) of the color coordinate b * is controlled to 3.5% or less to prevent the occurrence of yellowing and opacity, Unit and a liquid crystal display device.

<Measurement of penetration distance>

Manufacturing example  2. Preparation of acrylic resin (B)

80 parts by weight of ethylhexyl acrylate (EHA) was added to a 1 L reactor equipped with a cooling device so that nitrogen gas was refluxed and temperature was easily controlled. 20 parts by weight of 2-hydroxyethyl acrylate (HEA) was added, and ethyl acetate (EAc) was added as a solvent. Subsequently, nitrogen gas was purged for about 1 hour to remove oxygen, and the mixture was homogenized while maintaining the temperature at 62 DEG C. Then, azobisisobutyronitrile diluted to 50% concentration in ethyl acetate as a reaction initiator (AIBN) were added thereto. Subsequently, the mixture was reacted to prepare an acrylic resin (B) having a weight average molecular weight of 500,000.

Example  3

Preparation of pressure-sensitive adhesive composition

1 part by weight of a multifunctional crosslinking agent (hexanediol diacrylate) and 3 parts by weight of an antioxidant (Irganox 1010, manufactured by Ciba Specialty Chemicals) were added to 100 parts by weight of the acrylic resin (B) to prepare a pressure- This was used to prepare a coating solution.

Fabrication of Backlight Unit

LED (thickness: 1.2 mm) the substrate is formed (width: 10cm, vertical: 10cm) the LED is completely sealed to the coating solution 1.5 mm illuminance 600 mW / cm ² and using a high pressure mercury lamp, the coating, and the thickness of such a And an ultraviolet ray having a light quantity of 150 mJ / cm ² was irradiated for 10 minutes to cure, thereby forming a pressure-sensitive adhesive layer. Then, a polyethylene terephthalate film (thickness: 50 μm) was laminated on the pressure-sensitive adhesive layer to complete a backlight unit.

Example  4 and Comparative Example  3, 4

A backlight unit was prepared in the same manner as in Example 3, except that the composition of the pressure-sensitive adhesive composition was changed as shown in Table 3 below.

Example Comparative Example 3 4 3 4 Acrylic resin (B) Content 100 100 100 100 Multifunctional Cross-linking agent  content 1.0 1.5 0.8 0.5 Antioxidant 3 3 3 3 Content Unit: parts by weight
Multifunctional crosslinking agent: hexanediol diacrylate
Antioxidant: Irganox 1010, manufactured by Ciba Specialty Chemicals Co.,

The properties of the backlight units prepared in Examples and Comparative Examples were measured by the following methods.

3. Extrusion distance measurement

As shown in Fig. 2, the backlight unit manufactured in the examples and the comparative example was put up and pressed _in a weight of 10 kg under a temperature condition of 60 캜, and after 5 minutes, The penetration distance of the pressure-sensitive adhesive layer was measured using a vernier caliper.

4. Evaluation of bending characteristics

The backlight units prepared in Examples and Comparative Examples were allowed to stand in an oven at 100 캜 for 24 hours, and the degree of curl was compared to evaluate the flexural properties according to the following criteria.

<Evaluation Criteria of Flexural Properties>

&Amp; cir &amp;: The height of occurrence of warpage from the reference plane is less than 5 mm

?: The height of warpage from the reference plane is less than 7 mm

?: Less than 15 mm in height of warpage from the reference plane

X: Less than 20 mm of warpage height from the reference plane

The results of the above physical property measurement are summarized in Table 4 below.

Example Comparative Example 3 4 3 4 Seepage distance ( mm ) 0 0 One 2 Warpage ◎ ◎ ◎ ◎

As can be seen from the results of Table 4, in the case of the backlight unit according to Examples 3 and 4 of the present invention, the penetration distance was 0 mm, but in the case of the backlight unit according to Comparative Examples 3 and 4, Were 1 mm and 2 mm, respectively.

That is, in the case of the example using the pressure-sensitive adhesive composition for a backlight unit according to the present invention, the penetration distance could be controlled to less than 1 mm by controlling the content of the polyfunctional crosslinking agent.

<Highest Heating temperature  For measuring>

Manufacturing example  3. Preparation of acrylic resin (C)

80 parts by weight of ethylhexyl acrylate (EHA) was added to a 1 L reactor equipped with a cooling device so that nitrogen gas was refluxed and temperature was easily controlled. 20 parts by weight of 2-hydroxyethyl acrylate (HEA) was added, and ethyl acetate (EAc) was added as a solvent. Subsequently, nitrogen gas was purged for about 1 hour to remove oxygen, and the mixture was homogenized while maintaining the temperature at 62 DEG C. Then, azobisisobutyronitrile diluted to 50% concentration in ethyl acetate as a reaction initiator (AIBN) were added thereto. Subsequently, the mixture was reacted to prepare an acrylic resin (C) having a weight average molecular weight of 500,000.

Example  5

Preparation of pressure-sensitive adhesive composition

0.2 parts by weight of a photoinitiator (hydroxycyclohexyl phenyl ketone, Irgacure 184, Ciba Specialty Chemicals, Inc.), 1 part by weight of a polyfunctional crosslinking agent (hexanediol diacrylate) and 100 parts by weight of an acrylic resin And 3 parts by weight of an antistatic agent (Irganox 1010, Ciba Specialty Chemicals, Inc.) were mixed to prepare a pressure-sensitive adhesive composition.

Fabrication of Backlight Unit

The coating liquid was coated to a thickness of 1.5 mm so as to completely encapsulate the LED on the substrate having the LED (thickness: 1.2 mm) formed thereon. Ultraviolet rays of 600 mW / cm ^{2 in} intensity and 150 mJ / cm ² in intensity were irradiated using a high- For 10 minutes to form a pressure-sensitive adhesive layer. Then, a polyethylene terephthalate film (thickness: 50 μm) was laminated on the pressure-sensitive adhesive layer to complete a backlight unit.

Example  6 and Comparative Example  5, 6

A backlight unit was prepared in the same manner as in Example 5, except that the composition of the pressure-sensitive adhesive composition was changed as shown in Table 5 below.

Example Comparative Example 5 6 5 6 The acrylic resin (C) 100 100 100 100 Photoinitiator 0.2 0.5 0.8 1.2 Multifunctional Cross-linking agent One One One One Antioxidant 3 3 3 3 Content Unit: parts by weight
Photoinitiator: Hydroxycyclohexyl phenyl ketone (Irgacure 184, Ciba Specialty Chemicals)
Multifunctional crosslinking agent: hexanediol diacrylate
Antioxidant: Irganox 1010, manufactured by Ciba Specialty Chemicals Co.,

The properties of the backlight units prepared in Examples and Comparative Examples were measured by the following methods.

5. The best you can reach during the curing process Heating temperature  Measure

As shown in FIG. 3, using the backlight unit manufactured in Examples and Comparative Examples, a specimen was prepared, and the temperature of the curing start point of the pressure-sensitive adhesive composition coated on the substrate on which the light source (LED) The temperature of the peak was measured while observing the temperature change from the completion of the curing to the completion of the curing.

6. The pressure-  Thickness deviation measurement

As shown in FIG. 4, using the backlight unit manufactured in Examples and Comparative Examples, a test piece was made and the thickness (Y ₁ ) of the pressure-sensitive adhesive layer at the top of the LED at the top of the LED was measured using a vernier caliper, The thickness (Y ₂ ) of the pressure-sensitive adhesive layer between the LEDs was measured and substituted into the general formula (4) to calculate the thickness deviation (?) Of the pressure-sensitive adhesive layer.

The results of the above physical property measurement are summarized in Table 6 below.

Example Comparative Example 5 6 5 6 Best Heating temperature 45 ° C 60 ° C 83 ℃ 102 ° C The pressure-  Thickness deviation 50 μm or less Greater than 50 μm
100 μm or less More than 220 ㎛ More than 300 ㎛

As can be seen from the results of Table 6, in the case of the backlight unit according to the embodiment of the present invention, the maximum exothermic temperature reached during the curing of the pressure-sensitive adhesive composition was 80 ° C or less, The thickness variation was less than 200 mu m. On the other hand, in the case of the backlight unit according to the comparative example of the present invention, the maximum exothermic temperature reached during curing of the pressure-sensitive adhesive composition exceeded 80 캜, and thus the thickness deviation of the pressure- Respectively.

That is, in the case of the example using the pressure-sensitive adhesive composition for a backlight unit according to the present invention, the maximum exothermic temperature was controlled at 80 ° C or less to minimize the thickness variation of the pressure-sensitive adhesive layer as a cured product of the pressure- I could provide one brightness.

10: Specimen for measuring rate of change of color coordinate b *
11: pressure-sensitive adhesive composition 12,24: plastic film
20: Specimen for measurement of penetration distance 21, 51:
22,52: Light source (LED) 23: Pressure sensitive adhesive composition
25: Addition of 10kg _{of the} 30: specimen in highest heat generation temperature measurement
31: Thermometer 32: Thermometer fixing device
40: Specimen for measuring the thickness deviation of the pressure-sensitive adhesive layer 41, 53: Pressure-
Y ₁ : Thickness of the pressure-sensitive adhesive layer at the upper right portion of the light source (LED)
Y ₂ : Thickness of the pressure-sensitive adhesive layer between the light source (LED) and the light source (LED)
50, 60, 70, 80: backlight unit 61:
71: diffusion plate 81: diffusion sheet
82: condensing sheet 90: liquid crystal display panel
100: liquid crystal display

Claims (19)

Acrylic resin; Multifunctional crosslinking agents; And 2.2 parts by weight to 30 parts by weight of an antioxidant based on 100 parts by weight of the acrylic resin, and satisfying the following general formula (1):
[Formula 1]
? B = | B _i - B _l | / | B _i | × 100? 3.5%
In the above general formula (1), B _i is a pressure-sensitive adhesive composition obtained by coating the pressure-sensitive adhesive composition with a thickness of 2.0 mm between two plastic films having a size of 5 cm × 5 cm (width × length) * Represents the initial color coordinate b * value measured using a colorimeter, and B ₁ represents the initial value of the chromaticity coordinates obtained by using the L * a * b * colorimeter after allowing the specimen to stand under constant temperature and humidity conditions of 80 ° C. and 90% RH for 24 hours. And the color coordinates b * of the color coordinates. The method according to claim 1,
Sensitive adhesive composition for a backlight unit wherein? B is 3% or less. The method according to claim 1,
The acrylic resin is a polymer of a monomer mixture comprising a (meth) acrylic acid ester monomer and a crosslinkable monomer,
Wherein the cross-linkable monomer is a monomer containing a hydroxyl group. The method of claim 3,
Wherein the (meth) acrylic acid ester-based monomer is alkyl (meth) acrylate. The method of claim 3,
The hydroxyl group-containing monomer may be at least one monomer selected from the group consisting of 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (Meth) acrylate, 2-hydroxyethyleneglycol (meth) acrylate, and 2-hydroxypropyleneglycol (meth) acrylate. The method of claim 3,
And the hydroxyl group-containing monomer is contained in an amount of 15 to 40 parts by weight based on 100 parts by weight of the acrylic resin. The method according to claim 1,
Wherein the multifunctional crosslinking agent is a polyfunctional (meth) acrylate. 8. The method of claim 7,
The polyfunctional (meth) acrylate may be at least one selected from the group consisting of hexanediol di (meth) acrylate, trimethylolpropane trioxyethyl di (meth) acrylate, alkylene glycol di (meth) acrylate, dialkylene glycol di (meth) , Trialkylene glycol di (meth) acrylate, dicyclopentenyl di (meth) acrylate, dicyclopentenyloxyethyl di (meth) acrylate, neopentyl glycol di (meth) acrylate, dipentaerythritol (Meth) acrylate, trimethylolpropane tri (meth) acrylate, and pentaerythritol tri (meth) acrylate. The pressure-sensitive adhesive composition for a backlight unit according to claim 1, The method according to claim 1,
Wherein the multifunctional crosslinking agent is contained in an amount of 0.9 to 10 parts by weight based on 100 parts by weight of the acrylic resin. The method according to claim 1,
Wherein the antioxidant is at least one selected from the group consisting of phenolic amides, benzene amines, phenolic esters, hindered amines, polymeric hindered phenols, hindered phosphites, and mixtures thereof. 11. The method of claim 10,
The phenolic amides are prepared by reacting N, N'-hexamethylenebis (3,5-di- (tert) -butyl-4-hydroxyhydrocinnamamide or tetrakis- (methylene- Butyl-4-hydrocinnamate)) methane,
The phenolic ester is ethylene bis (oxyethylene) bis- (3- (5-tert-butyl-4-hydroxy-m-tolyl) -propionate,
Heterocyclic amines include 1,3,5-triazine-2,4,6-triamine; N, N '' - [1,2-ethane-dies- bis [[[[4,6-bis- [butyl (1,2,2,6,6-pentamethyl-4-piperidinyl) ] -1,3,5-triazin-2-yl] imino] -3,1-propanediyl]] bis [N ', N "-dibutyl-N', N" , 2,2,6,6-pentamethyl-4-piperidinyl); 1,6-hexanediamine; Polymers of 2,4,6-trichloro-1,3,5-triazine and N, N'-bis (2,2,6,6-tetramethyl-4-piperidinyl); Or a reaction product of N-butyl-1-butanamine and N-butyl-2,2,6,6-tetramethyl-4-piperidinamine,
Polymeric hindered phenols are 2,2,4-trimethyl-1,2-dihydroxyquinoline,
Disulfide phosphites include bis (2,4-di-t-butylphenyl) pentaerythritol diphosphite; Or tris (2,4-di-tert-butyl-phenyl) phosphite. delete Board;
At least one light source formed on the substrate; And
And a pressure-sensitive adhesive layer containing a cured product of the pressure-sensitive adhesive composition for a backlight unit according to any one of claims 1 to 11, which encapsulates the light source. 14. The method of claim 13,
Backlight unit with LED light source. 14. The method of claim 13,
And a reflective plate formed between the substrate and the light source. 14. The method of claim 13,
And a diffuser plate formed on the pressure-sensitive adhesive layer. 17. The method of claim 16,
Further comprising a plurality of optical sheets formed on the diffuser plate. 18. The method of claim 17,
Wherein the plurality of optical sheets include at least a diffusion sheet and a light condensing sheet. A backlight unit according to claim 13; And a liquid crystal display panel formed on the backlight unit.

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