KR101515437B1 - Adhesive composition for liquid crystal device and method of manufacturing the same - Google Patents

Abstract

The adhesive composition for a liquid crystal display according to an embodiment of the present invention includes an adhesive resin and a black pigment and is applied on a partial area of a lower surface of a liquid crystal panel or a partial area of a backlight unit of a liquid crystal display device, Bond the unit. The adhesive composition for a liquid crystal display according to the present invention makes it possible to manufacture a lightweight and thinned liquid crystal display device by firmly bonding a liquid crystal panel and a backlight unit. In addition, since the black pigment is dispersed in the adhesive composition, light emitted from the backlight unit is prevented from escaping to the outside of the LCD module, and the efficiency of the liquid crystal panel can be enhanced. In addition, it is possible to apply it by a simple process, and there is no need for an additional process after coating, thereby reducing cost.

Description

TECHNICAL FIELD [0001] The present invention relates to an adhesive composition for a liquid crystal display, and a method of manufacturing the adhesive composition.

TECHNICAL FIELD The present invention relates to an adhesive composition for a liquid crystal display, and more particularly, to an adhesive composition for a liquid crystal display for bonding a liquid crystal panel and a backlight unit and a method for manufacturing the same.

In recent years, flat panel displays have demanded excellent characteristics such as thinning, light weight, and low consumption strategy. Of these, liquid crystal display devices have been widely used in notebooks, netbooks, and televisions because of their excellent resolution, color display, and image quality.

In such a liquid crystal display device, a liquid crystal panel formed by laminating two liquid crystal layers between two adjacent substrates is an essential component, and the direction of arrangement of liquid crystal molecules is changed by an electric field in the liquid crystal panel to realize a difference in transmittance. However, since the liquid crystal panel does not have its own light emitting element, a separate light source is required to display the difference in transmittance as an image. To this end, a backlight unit having a light source is disposed on the back surface of the liquid crystal panel.

Conventionally, a process of assembling a liquid crystal panel and a backlight unit using a top cover was used. However, there is a problem in that the liquid crystal display device which is recently required is thinned and lightened, and there is also a problem that the unnecessary processing cost by the top cover increases greatly. Accordingly, a liquid crystal display device or the like having a top cover removed has been manufactured recently. In such a liquid crystal display device, a side cover having a panel side supporting means is provided for lateral support of the liquid crystal panel. However, in this case, banding of the liquid crystal panel is required in assembling the liquid crystal panel, and in this case, there is a problem that the liquid crystal panel is broken due to the bending stress of the liquid crystal panel, or the vertex portion is broken.

In order to solve such a problem, a method of bonding the edge of the backlight unit or the edge of the liquid crystal panel using an adhesive tape has been introduced. However, when the adhesive tape is used, the release paper of the adhesive tape is integrally attached to the front surface of the adhesive tape. At this time, the releasing paper is formed on the entire surface of the bonding portion, so that the air between the optical sheets can not escape. Therefore, when the panel is put in the vacuum chamber for attaching the panel, a failure of the backlight unit to pop up occurs. In addition, when the release paper is detached, some of the adhesive tape may fall off together with the release paper. Particularly, when the releasing paper is attached to the adhesive tape, the adhesive portion of the adhesive tape adheres to the adhesive tape. Also, light leakage from the backlight unit to the outside through the space in which the adhesive tape is adhered is generated, thereby lowering the efficiency of the liquid crystal panel.

SUMMARY OF THE INVENTION The present invention has been made to overcome the above-described problems, and an object of the present invention is to provide a liquid crystal display device having a liquid crystal panel and a backlight unit bonded together, and having a shading function for blocking light emitted from a backlight unit from escaping to the outside To provide an adhesive composition.

Another object of the present invention is to provide an adhesive composition for a liquid crystal display device which can be applied by a simple process and which does not require an additional step after coating.

The adhesive composition for a liquid crystal display according to an embodiment of the present invention includes 10 to 30 parts by weight of a black pigment in 100 parts by weight of an adhesive resin and is applied on a part of the lower surface of the liquid crystal panel or a part of the backlight unit of the liquid crystal display Thereby bonding the liquid crystal panel and the backlight unit.

The adhesive resin may be a liquid polyurethane resin.

The adhesive composition for a liquid crystal display according to another embodiment of the present invention comprises 10 to 30 parts by weight of a black pigment, 10 to 30 parts by weight of an elastic resin and 1 to 10 parts by weight of a curing accelerator in 100 parts by weight of an adhesive resin, Is applied onto a part of the lower surface of the liquid crystal panel or a part of the backlight unit to bond the liquid crystal panel and the backlight unit.

The black pigment is at least one kind of black pigment such as carbon black, iron oxide, carbon nanotube or graphite, and may have an average particle diameter of 13 to 70 nm.

0.05 to 20 parts by weight of at least one inorganic filler such as silica, aluminum oxide, clay or talc.

The elastic resin may be an epoxy resin having a viscosity at 45 ° C of 25,000 to 30,000 cPs and a molecular weight of 5,500 to 6,000 g / mol.

A method for preparing an adhesive composition for a liquid crystal display according to another embodiment of the present invention includes: preparing a first mixture containing an isocyanate compound; Preparing a second mixture comprising a polyol compound, a black pigment, an elastic resin and a curing accelerator; And injecting the first mixture and the second mixture into the liquid syringe vessel.

The volume ratio of the first mixture and the second mixture may be 50:40 to 50:60.

The first mixture and the second mixture introduced into the liquid syringe vessel may be pressurized and mixed in a mixer formed at a discharge port at the end of the liquid syringe vessel and discharged through the discharge port.

The adhesive composition for a liquid crystal display according to the present invention makes it possible to manufacture a lightweight and thinned liquid crystal display device by firmly bonding a liquid crystal panel and a backlight unit. Also, since the black pigment is dispersed in the adhesive composition, light emitted from the backlight unit is prevented from escaping to the outside of the LCD module, and the light efficiency of the liquid crystal panel can be increased.

In addition, it is possible to apply it by a simple process, and there is no need for an additional process after coating, thereby reducing cost.

Hereinafter, the adhesive composition for a liquid crystal display according to the present invention will be described in detail. However, the following description is only an exemplary description of the present invention, and the technical idea of the present invention is not limited by the following description, and the technical idea of the present invention is defined by the claims that follow.

An adhesive composition for a liquid crystal display according to an embodiment of the present invention includes an adhesive resin and a black pigment and is applied on a partial area of a lower surface of a liquid crystal panel of a liquid crystal display device to bond the liquid crystal panel and the backlight unit. As this adhesive resin, it is preferable to use this liquid type polyurethane. The liquid polyurethane refers to a polyurethane formed by mixing an isocyanate compound and a polyol compound. One-component polyurethane having a urethane group in a single composition can be simply applied and adhered, but is unstable and has a difficult storage condition and has a lower adhesive force than the liquid polyurethane. Also, it is difficult to mix black pigments in order to prevent light leakage, which is a major feature of the adhesive composition for a liquid crystal display according to an embodiment of the present invention. This liquid type polyurethane is troublesome to use an isocyanate compound and a polyol compound in a mixed state, but it is preferable to use the liquid type polyurethane because it can mix a black pigment having a high adhesive strength and a light shielding effect.

The isocyanate compound may be a diisocyanate compound. Examples of the isocyanate compound include methylenediphenyl diisocyante (MDI), p-phenylene diisocyanate (PPDI), 1,6-hexamethylene diisocyanate (HDI), toluene diisocyanate (TDI), 1,5-naphthalene diisocyanate (NDI), isoporon diisocyanate (IPDI), and isophorone diisocyanate Cyclohexylmethane diisocyanate (H12MDI), and the like.

Examples of the MDI include SR500 (manufactured by Kumho Mitsui Chemicals), M200 (manufactured by Kumho Mitsui Chemicals), C930 (manufactured by Chemtura), E530D (manufactured by Chemtura) or 4,4'-methylene diphenyl diisocyanate -ethylenediphenyl diisocyante (TCI) can be used. As the HDI, 50M-HDI (manufactured by Asahi KASEI) can be used.

As the polyol compound, a diol compound is preferably used, and 1,4-butanediol may be used. PPG1000D (manufactured by Kumho Petrochemical), PPG2000D (manufactured by Kumho Petrochemical), PPG3000D (produced by Kumho Petrochemical Co., Ltd.), PPG200D (manufactured by Kumho Petrochemical), PPG400D ), PPG3322 (manufactured by Kumho Petrochemical), and PPG5815 (manufactured by Kumho Petrochemical).

As the black pigment used in the adhesive composition for a liquid crystal display according to an embodiment of the present invention, a black substance such as carbon black, iron oxide, carbon nanotube or graphite may be used. The black pigment preferably has an average particle diameter of 13 to 70 nm. When the size of the particles is too small, it is difficult to disperse in the bonding resin, so that the light-shielding effect is deteriorated. On the other hand, if the particle size is too large, the adhesive strength is lowered. In order to sufficiently disperse the black pigment in the composition, two or more kinds of black pigments having different particle sizes may be used. As the black pigment, it is preferable to use carbon black in terms of processability and cost. The black pigment is preferably used in an amount of 10 to 30 parts by weight based on 100 parts by weight of the adhesive resin. When the black pigment is added in an amount exceeding 30 parts by weight, the adhesive force may be reduced, and the light emitted from the backlight may be absorbed by the adhesive, thereby reducing the efficiency of the liquid crystal panel. On the other hand, when the black pigment is added in an amount of less than 10 parts by weight, it is not possible to efficiently prevent light leakage.

The adhesive composition for a liquid crystal display according to an embodiment of the present invention includes an adhesive resin and a black pigment, and includes an elastic resin and a curing accelerator. The elastic resin serves to improve the adhesion of the adhesive composition for a liquid crystal display according to an embodiment of the present invention and to improve the elongation. In manufacturing a liquid crystal display device, when a physical distortion occurs during the process, defects may occur in which the liquid crystal panel and the backlight unit are separated from each other. When the elongation increases, it plays a role in reducing the incidence of such failure. It also maintains adhesive strength under severe and thermal shock conditions.

The elastic resin is used in an amount of 5 to 30 parts by weight based on 100 parts by weight of the adhesive resin. At this time, when the elastic resin is added in an amount exceeding 30 parts by weight, the adhesive force is deteriorated. When the amount is less than 5 parts by weight, an intended adhesive force can not be obtained and the durability is deteriorated. The elastic resin may be an epoxy resin. The elastic resin preferably has a viscosity of 25,000 to 30,000 cPs at 45 DEG C and a molecular weight of 5,500 to 6,000 g / mol. Specific examples of the elastic resin include polybutadiene, glycidyl ester, epoxynovorax, and bisphenol A. Further, commercially available PB3600 (manufactured by DALCEL chemical), PB4700 (manufactured by DALCEL chemical), and VTBN (manufactured by CVC Thermoset Specialties) can be used as the epoxy resin.

1 to 10 parts by weight of the curing accelerator is added so that the adhesive resin is mixed with an isocyanate compound and a polyol compound to cause a polymerization reaction and then applied at room temperature. At this time, when it is added in an amount exceeding 10 parts by weight, the adhesive composition for an LCD device is excessively cured during application of the adhesive composition for a liquid crystal display, resulting in deterioration of adhesive strength. When the amount is less than 1 part by weight, it takes a long time to cure the adhesive composition, thereby decreasing the process efficiency. As the curing accelerator, dibutyltin dilaurate and 2- (methylamino) ethanol may be used.

The adhesive composition for a liquid crystal display according to an embodiment of the present invention may further include 0.05 to 20 parts by weight of an inorganic filler. As the inorganic filler, inorganic fillers such as silica, aluminum oxide, clay or talc may be used alone or in combination. As the inorganic filler, commercially available Aerosil R8200 (manufactured by EVONIK) or Aerosil R200 (manufactured by EVONIK) can be used.

According to another embodiment of the present invention, there is provided a method of manufacturing an adhesive composition for a liquid crystal display, comprising: preparing a first mixture containing an isocyanate compound; Preparing a second mixture comprising a polyol compound, a black pigment, an elastic resin and a curing accelerator; Introducing the first mixture and the second mixture into the liquid syringe vessel; And pressurizing the first mixture and the second mixture introduced into the liquid type syringe vessel and mixing and discharging the mixture in a mixer formed at a discharge port at the end of the liquid type syringe vessel.

The constituent components of the isocyanate compound, the polyol compound, the black pigment, the elastic resin and the curing accelerator, which are included in the adhesive composition for a liquid crystal display according to the embodiment of the present invention, are described above and are omitted for avoiding duplication.

The isocyanate compound is weighed and prepared in a container, and the second mixture containing the polyol compound, the black pigment, the elastic resin and the curing accelerator is prepared in a separate container. At this time, the sum of the amounts of the isocyanate compound and the polyol compound is set as a reference. That is, 10 to 30 parts by weight of a black pigment, 10 to 30 parts by weight of an elastic resin, and 1 to 10 parts by weight of a curing accelerator are added based on 100 parts by weight of an isocyanate compound and a polyol compound. The prepared first mixture and the second mixture are put into the liquid type syringe vessel one after another at room temperature or simultaneously. At this time, the volume ratio of the first mixture and the second mixture is 50:40 to 50:60. When the first mixture and the second mixture introduced into the liquid syringe vessel are pressurized, they are discharged through the discharge port at the end of the liquid syringe vessel. At this time, a mixer for mixing the first mixture and the second mixture is formed in the discharge port. The first mixture and the second mixture are mixed together to form an adhesive containing the bonding resin. The adhesive is applied to a part of the lower surface of the liquid crystal panel or a part of the backlight unit during the manufacturing process of the liquid crystal display to bond the liquid crystal panel and the backlight unit.

Hereinafter, the present invention will be described in more detail with reference to specific examples. However, the technical idea of the present invention is not limited by the following embodiments.

Example  One

[ Liquid type  Preparation of polyurethane adhesive composition]

100 g of PTMEG isocyanate (E530D, manufactured by Chemtura) was taken out of the vessel and the mixture A was prepared.

43.14 g of polypropylene glycol (PPG2000D, manufactured by Kumho Petrochemical), 19.61 g of carbon black (TBK 1099R, manufactured by CABOT), 29.41 g of polybutadiene epoxy resin (PB3600, manufactured by DALCEL chemical) (Manufactured by Aldrich) and 5.88 g of fumed silica (aerosil 8200, manufactured by EVONIK) were prepared in a vessel separate from the mixture A.

The viscosities of mixture A and mixture B measured by RE-215U (Toki Sangyo) were 38,300 cPs and 46,000 cPs, respectively.

Mixtures A and B were placed in a 500 ml cylindrical syringe barrel at a volume ratio of 50:50 and then extruded.

Example  2

[ Liquid type  Preparation of polyurethane adhesive composition]

100 g of PTMEG isocyanate (E530D, manufactured by Chemtura) was taken out of the vessel and the mixture A was prepared.

49.00 g of polypropylene glycol (PPG2000D, manufactured by Kumho Petrochemical), 22.20 g of carbon black (TBK 1099R, manufactured by CABOT), 26.60 g of polybutadiene epoxy resin (PB3600, manufactured by DALCEL chemical) (Aldrich) (2.20 g) were prepared in a container separate from the mixture A.

The viscosities of mixture A and mixture B measured by RE-215U (Toki Sangyo) were 38,300 cPs and 6,100 cPs, respectively.

Mixtures A and B were placed in a 500 ml cylindrical syringe barrel at a volume ratio of 50:50 and then extruded.

Example  3

[ Liquid type  Preparation of polyurethane adhesive composition]

100 g of PTMEG isocyanate (E530D, manufactured by Chemtura) was taken out of the vessel and the mixture A was prepared.

45.83 g of polypropylene glycol (PPG2000D, manufactured by Kumho Petrochemical), 20.84 g of carbon black (TBK 1099R, manufactured by CABOT), 31.25 g of polybutadiene epoxy resin (PB3600, manufactured by DALCEL chemical) (Aldrich) (2.08 g) was prepared in a container separate from the mixture A.

The viscosities of mixture A and mixture B measured by RE-215U (Toki Sangyo) were 38,300 cPs and 10,000 cPs, respectively.

Mixtures A and B were placed in a 500 ml cylindrical syringe barrel at a volume ratio of 50:50 and then extruded.

Comparative Example  One

100 g of PTMEG isocyanate (E530D, manufactured by Chemtura) was taken out of the vessel and the mixture A was prepared.

, 25.64 g of carbon black (TBK 1099R, manufactured by CABOT), 15.38 g of polybutadiene epoxy resin (PB3600, manufactured by DALCEL chemical), 0.25 g of dibutyl tin dilaurate (Aldrich) (2.56 g) was prepared in a container separate from the mixture A.

The viscosities of mixture A and mixture B measured by RE-215U (Toki Sangyo) were 38,300 cPs and 4,000 cPs, respectively.

Mixtures A and B were placed in a 500 ml cylindrical syringe barrel at a volume ratio of 50:50 and then extruded.

[Performance evaluation]

Adhesive performance evaluation

The adhesive compositions prepared in Examples 1, 2 and 3 and Comparative Example 1 were applied to a glass plate to a thickness of 500 mu m. After 12 hours had elapsed from bonding the glass plate to another glass plate or PC substrate, the adhesive force was measured by a dynamic shear method and a peel off method. The results are shown in Table 1.

Light beam  Prevention evaluation

The adhesive compositions prepared in Examples 1, 2 and 3 and Comparative Example 1 were applied to a glass plate to a thickness of 500 mu m. After 12 hours, the absorptivity was measured at a wavelength of 400-600 nm using UV. The results are shown in Table 1.

Elongation evaluation

The adhesive compositions prepared in Examples 1, 2 and 3 and Comparative Example 1 were applied to a glass plate with a thickness of 500 탆 and a width of 10 탆. After 12 hours, the elongation was measured with the cured specimen. The results are shown in Table 1.

Evaluation items Example 1 Example 2 Example 3 Comparative Example 1 Adhesive performance
Dynamic Shear
(kgf / cm ² ) 11.280 9.636 11.693 9.851 Peel Off (N) 27.852 14.126 29.670 9.864 Light leakage phenomenon
Prevention OD (400-600 nm,
Thickness: 500 탆, Max: 5) 5 5 5 5 Elongation Elongation (thickness: 500 mu m,
Width: 10 mm,%) 880 740 890 540

Claims (12)

delete delete 10 to 30 parts by weight of a black pigment, 10 to 30 parts by weight of an elastic resin and 1 to 10 parts by weight of a curing accelerator in 100 parts by weight of an adhesive resin,
An adhesive composition for a liquid crystal display, which is applied on a part of a lower surface of a liquid crystal panel of a liquid crystal display device or on a part of a backlight unit, and bonds the liquid crystal panel and the backlight unit.
The method of claim 3,
Wherein the adhesive resin is a liquid type polyurethane resin.
The method of claim 3,
Wherein the black pigment is at least one kind of pigment selected from the group consisting of carbon black, iron oxide, carbon nanotube and graphite.
6. The method of claim 5,
Wherein the black pigment has an average particle diameter of 13 to 70 nm.
The method of claim 3,
And 0.05 to 20 parts by weight of at least one inorganic filler selected from the group consisting of silica, aluminum oxide, clay and talc.
The method of claim 3,
Wherein the elastic resin has a viscosity of 25,000 to 30,000 cPs at 45 DEG C and a molecular weight of 5,500 to 6,000 g / mol.
9. The method of claim 8,
Wherein the elastic resin is an epoxy resin.
Preparing a first mixture comprising an isocyanate-based compound;
Preparing a second mixture comprising a polyol compound, a black pigment, an elastic resin and a curing accelerator; And
Introducing the first mixture and the second mixture into the liquid syringe vessel;
Wherein the adhesive composition for a liquid crystal display device comprises:
11. The method of claim 10,
Wherein the volume ratio of the first mixture and the second mixture is 50:40 to 50:60.
11. The method of claim 10,
Pressurizing the first mixture and the second mixture introduced into the liquid syringe vessel and mixing the mixed mixture in a mixer formed at a discharge port at the end of the liquid syringe vessel and discharging the mixture through the discharge port Gt; < / RTI >