KR20100069206A - Curable resin composition for dot printing on a surface of light guide plate by inkjet method, light guide plate, backlight unit and liquid crystal display device using the same - Google Patents

Abstract

PURPOSE: A photo-curable resin composition, a light guide plate using thereof, and a backlight unit and a liquid crystal display apparatus are provided to form multiple printing dots on the light guide plate of the liquid crystal display, and to improve the productivity of the composition. CONSTITUTION: A photo-curable resin composition for forming a light guide plate dot using an inkjet method contains hydrophilic (meth)acrylate marked as chemical formula 1, multi-functional (meta)acrylate with more than two (meta)acrylate groups, and a photoinitiator. In the chemical formula 1, R1 is either ethylene or propylene. R2 is either a hydrogen atom or methyl. Y is either the hydrogen atom, an ethylene unsaturated group, or straight-chain hydrocarbon with the carbon number of 1~50. N is an integer selected from 1~50. 1~80 parts of hydrophilic (meth)acrylate by weight is included from 100 parts of photo-curable resin composition by weight.

Description

Curable Resin Composition for Dot Printing on a Surface of Light Guide Plate by Inkjet Method, Light Guide Plate, Backlight Unit and Liquid Crystal Display Device Using the Same}

The present invention relates to a light-curing resin composition for forming a light guide plate dot using the inkjet method, and more particularly, when used as an ink in the method of manufacturing a light guide plate using the inkjet method, excellent luminance uniformity, adhesion to a substrate, fast curing speed and The present invention relates to a photocurable resin composition having excellent dimensional stability after curing, which can be usefully used for light guide plate dot formation, and a light guide plate for a liquid crystal display device, a backlight unit, and a liquid crystal display device using the same.

In general, a liquid crystal display (Liquid Crystal Display) is a flat panel display device that displays an image by using a liquid crystal (Liquid Crystal), thinner and lighter than other display devices, has the advantage of low driving voltage and low power consumption As a result, it is widely used throughout the industry, and the use ratio of small electronic products such as mobile communication terminals is gradually increasing.

Such a liquid crystal display device requires a light assembly for providing separate light because the liquid crystal display panel for displaying an image is a non-light emitting device that does not emit light by itself.

The light assembly includes at least one lamp for generating light and a light guide plate for guiding the light generated from the lamp and emitting the light toward the liquid crystal display panel. At this time, the light generated from the lamp is totally reflected inside the light guide plate according to Snell's law, and is scattered and reflected by the reflective pattern formed on the lower surface of the light guide plate and the reflecting plate disposed under the light guide plate to be emitted toward the liquid crystal display panel.

In general, the light guide plate is manufactured by an injection molding machine. In this case, the injection machine has an injection passage of a sprue portion, a runner portion, a gate portion, and the like, and an acrylic resin of PMMA (polymethyl methacrylate) series for forming a light guide plate is injected into the injection molding machine through the injection passage.

However, when manufacturing the light guide plate in this manner, the acrylic resin present in the sprue portion, the runner portion and the gate portion is discarded after cutting the light guide plate, resulting in loss of material. In addition, when the light guide plate connected to the gate is cut through the thermal scissors, the cutting surface of the light guide plate may not be smooth, resulting in a deterioration in appearance quality. In addition, it is difficult to manufacture a plurality of light guide plate at the same time has a problem that the manufacturing time is long.

In order to solve this problem, a light guide plate manufactured by introducing a dot pattern shape onto a substrate by using an inkjet printing method has been proposed in recent years. This light guide plate manufacturing method has the advantage of short manufacturing time and continuous process, but it is difficult to attach photocurable resin used as ink on the base film and slow curing speed requires post-curing process after curing, and dimensional stability is deteriorated. have.

Accordingly, an object of the present invention is to provide a light-curing resin composition for light-guide plate dot formation using the ink-jet method, which can improve productivity due to excellent adhesion, dimensional stability, and fast curing speed when manufacturing the light-guide plate by the inkjet method.

Furthermore, another object of the present invention is to provide a light guide plate having a predetermined pattern having a microlens shape by dot-forming the photocurable resin composition on one or both surfaces of a substrate by an inkjet method.

In addition, another object of the present invention is to provide a backlight unit including the light guide plate.

In addition, another object of the present invention is to provide a liquid crystal display device including the backlight unit.

The present invention for achieving the above object is to include a hydrophilic (meth) acrylate represented by the following formula (1), a polyfunctional (meth) acrylate containing two or more intramolecular (meth) acrylate groups and a photoinitiator It provides the light-curing resin composition for light guide plate dot formation using the inkjet method characterized by the above-mentioned.

[Formula 1]

In Formula 1, R ₁ is ethylene or propylene, R ₂ is a hydrogen atom or a methyl group, Y is a hydrogen atom or an ethylenically unsaturated group or a straight or branched hydrocarbon having 1 to 50 carbon atoms, and n is 1 to 50 Is an integer.)

The hydrophilic (meth) acrylate may be included 1 to 80 parts by weight based on 100 parts by weight of the total photocurable resin composition.

As for the polyfunctional (meth) acrylate in which 2 or more (meth) acrylate groups are contained in the said molecule | numerator, it is preferable to use the thing whose viscosity is 1-2000 cps.

The polyfunctional (meth) acrylate is preferably contained 5 to 60 parts by weight based on 100 parts by weight of the total photocurable resin composition.

As the photoinitiator, it is preferable to use one or more selected from the group of benzene ethers, benzyl ketals, alpha hydroxy alkyl phenones, and amino alkyl phenones.

The photoinitiator may include 0.1 to 10 parts by weight based on 100 parts by weight of the total photocurable resin composition.

In addition, the photocurable resin composition preferably has a viscosity of 1 to 50 cps.

In addition, the photocurable resin composition preferably has a refractive index of 1.4 to 1.6.

In order to achieve another object of the present invention, the present invention, a light guide plate comprising a microlens-shaped pattern manufactured by dot-curing the photocurable resin composition on the one side or both sides of the base film by an inkjet method and then curing the dot. To provide.

It is preferable to use the base film that the plasma treatment of one side or both sides.

The base film may be selected from polyethylene terephthalate, polycarbonate, polymethyl methacryl.

In order to achieve another object of the present invention, the present invention provides a backlight unit comprising the light guide plate.

In order to achieve another object of the present invention, the present invention provides a liquid crystal display device comprising the backlight unit.

The photocurable resin composition according to the present invention contains a hydrophilic (meth) acrylate, and as the surface of the substrate before dot formation is converted to hydrophilic through plasma treatment, the photocurable resin composition according to the present invention is applied to the surface of the substrate. If the dot is formed, both are strongly attached and have an advantage of excellent adhesion.

Therefore, the photocurable resin composition which concerns on this invention has the effect that it can apply very usefully to manufacture the light-guide plate for backlight units of a liquid crystal display element using the inkjet method.

Hereinafter, the present invention will be described in more detail. Since the following description is a detailed description of one embodiment, the scope of the rights defined by the claims is not limited, even if there is a assertive, limited expression.

The photocurable resin composition which concerns on this invention contains a hydrophilic (meth) acrylate (A), a polyfunctional (meth) acrylate (B), and a photoinitiator (C). The detailed description of each component is as follows.

(A) hydrophilic (meth) acrylate

The photocurable resin composition according to the present invention includes a hydrophilic (meth) acrylate in order to improve adhesion to the substrate. The hydrophilic (meth) acrylate includes a hydrophilic (meth) acrylate represented by the following Formula 1 consisting of repeating units of ethylene oxide / propylene oxide ring opening.

[Formula 1]

(In Formula 1, R1 is ethylene or propylene, R2 is a hydrogen atom or a methyl group, Y is a hydrogen atom or an ethylenically unsaturated group or a straight or branched hydrocarbon of 1 to 50 carbon atoms, n is an integer of 1 to 50 .)

Specific examples of the formula (1) include polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, trimethanol protanethylene added tri (meth) acrylate, trimethanol propane propylene added tri (meth) acryl Rate, pentaerythritol ethylene-butyric tri (meth) acrylate, pentaerythritol propylene-butyric tri (meth) acrylate, dipentaerythritol ethylene-butane penta (meth) acrylate, dipentaerythritol propylene-butane penta (meth) acrylate, methoxy One or more types selected from polyethylene glycol mono (meth) acrylate and ethoxy polyethylene glycol mono (meth) acrylate can be used.

In particular, the hydrophilic (meth) acrylate of the present invention is not only adhered to the substrate surface into which the hydrophilic group has been introduced due to the plasma treatment, but also attached to the microlens having a shape giving a difference in surface energy between the composition and the substrate and curing. It plays a role in maintaining the shape afterwards.

The hydrophilic (meth) acrylate is preferably contained 1 to 80 parts by weight based on 100 parts by weight of the total photocurable resin composition, if the content is less than 1 part by weight it is difficult to improve the adhesion, the content is 80 parts by weight The surface energy difference is so big that shape preservation is not easy.

(B) polyfunctional (meth) acrylate

The photocurable resin composition which concerns on this invention contains polyfunctional (meth) acrylate. The polyfunctional (meth) acrylate is used for the purpose of improving the curing rate, it is preferable to use two or more (meth) acrylate groups in the molecule and a viscosity of 1 to 2000cps.

As such a polyfunctional (meth) acrylate, for example, dipentaerythritol hexa (meth) acrylate, dipentaerythritol penta (meth) acrylate, pentaerythritol tetra (meth) acrylate, pentaerythritol tree (meth) ) Acrylic acid, Itrimethylol propane tetra (meth) acrylate, trimethylol propane tri (meth) acrylate, glycerol tri (meth) acrylate, tris (2-hydroxyethyl) isocyanurate tri (meth) acryl Late, bis (2-hydroxyethyl) isocyanurate di (meth) acrylate, 1,3-butanedioldi (meth) acrylate, 1,4-butanedioldi (meth) acrylate, 1 At least one (meth) acrylate selected from, 6-hexanediol di (meth) acrylate, neopentylglycol di (meth) acrylate, 1,4-cyclohexanedimethanol diacrylate, and the like can be used.

It is preferable to use 5 to 60 parts by weight with respect to 100 parts by weight of the total photocurable resin composition as the polyfunctional (meth) acrylate having a fast curing rate is less than 5 parts by weight, which is difficult to be attributed to the improvement of the curing speed and exceeds 60 parts by weight. There is a problem of discharge due to the increase in viscosity.

In addition, in the photocurable resin composition of the present invention, in addition to the polyfunctional (meth) acrylate having two or more (meth) acrylate groups in the molecule, other monofunctional (methacrylate) can be used, and the structure is not particularly limited, and vinyl ether System (meth) acrylates can also be used.

Specific examples include hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, isooctyl (meth) acrylate, iso-decyl (meth) acrylate, stearyl At least one selected from the group consisting of (meth) acrylate, tetrahydroperfuryl (meth) acrylate, 2-phenoxyethyl (meth) acrylate, isobornol (meth) acrylate, N-vinylpyrrolidinone, and the like The (meth) acrylate of can be used.

(C) photoinitiator

The photocuring resin composition which concerns on this invention contains a photoinitiator. As a photoinitiator, it can select and use from what is generally used in the art. In particular, a benzene ether, benzyl ketal, alpha hydroxy alkylphenone, amino alkyl phenone, phosphine oxide can be used. For example, 2-methyl-1- [4- (methylthio) phenyl] 2-morpholinepropanone-1, diphenyl ketone benzyldimethyl ketal, 2-hydroxy-2-methyl-1-phenyl-1- On, 4-hydroxy cyclophenyl ketone, dimethoxy-2-phenylatetophenone, anthraquinone, fluorene, triphenylamine, carbazole, 3-methylacetophenone, 4-knoloacetophenone, 4,4- Dimethoxyacetophenone, 4,4-diaminobenzophenone, 1-hydroxycyclohexyl phenyl ketone, 2,4,6-trimethylbenzoyl-diphenyl-phosphineoxide, bis (2,9-dimethoxybenzoyl)- 2,4,4-trimethylpentylphosphine oxide or bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide and the like can be used alone or in combination. Preferably, at least one of benzene ether, benzyl ketal, alpha hydroxy alkyl phenone and amino alkyl phenone initiators may be used.

The photoinitiator is preferably included 0.1 to 10 parts by weight based on 100 parts by weight of the total photocurable resin composition, the content is less than 0.1 parts by weight of the curing rate is slow, if the content exceeds 10 parts by weight of the yellowing phenomenon is worse There is this.

In addition to the above components, various additives generally used in the art may be further added within the scope of not changing the features of the present invention.

The photocurable resin composition which concerns on this invention which consists of organic combination of a specific component as mentioned above has a viscosity in 25 degreeC of 1-50 cps, and has a refractive index of 1.4-1.6.

The photocurable resin composition may be usefully used for optical components and the like, and may be particularly useful for dot formation of a light guide plate using an inkjet method, and exhibits excellent optical properties with high adhesion when applied to the light guide plate.

Accordingly, the present invention provides a light guide plate having a microlens-shaped pattern manufactured by dot-curing the photocurable resin composition according to the present invention on one or both surfaces of a base film by an inkjet method. The configuration of the light guide plate is not limited and may employ various structures known in the art.

As the base material for applying the photocurable resin composition, a transparent optical polymer base material such as polyethylene terephthalate (hereinafter PET), polycarbonate (hereinafter PC) and polymethyl methacrylate (hereinafter referred to as PMMA) can be used.

The base film may be used after plasma treatment of one side or both sides, and the plasma treatment is generally performed in the art to introduce a hydrophilic group on the surface to maximize adhesion to ink. Therefore, the photocurable ink composition according to the present invention includes a hydrophilic (meth) acrylate, and as the base film includes a hydrophilic group through a plasma treatment, the adhesive force is maximized by the interaction with each other.

The thickness of a film is about 10-1000 micrometers, Preferably 50-300 micrometers is used.

The irradiation amount of UV light is about 0.1-2 J / cm <2>, Preferably it is 0.4-0.8 J / cm <2>, The wavelength is not specifically limited, A mercury, a metal halide, and an electrodeless lamp which are used normally can be used.

The light guide plate manufactured as described above has excellent productivity due to the fast curing speed during manufacturing, and the light guide plate manufactured after curing has high brightness and little breakage of shape, and has excellent color change, yellowing resistance, and adhesion to the film. In addition, when exposed to backlight light, a sufficient amount of backlight light passes through the opening to the liquid crystal of the LCD panel.

The present invention also provides a backlight unit having the light guide plate. The backlight unit is not limited and may employ a structure known in the art. For example, a diffusion sheet, a prism sheet, or the like can be provided on a light source such as an LED or an upper surface of the light guide plate from the present invention.

Moreover, this invention provides the liquid crystal display device provided with the said backlight unit. The liquid crystal display device is also not limited in structure, and may employ a structure known in the art.

The present invention will be further illustrated by the following examples, which are only specific examples of the present invention, and are not intended to limit or limit the protection scope of the present invention.

Examples 1 to 7, Comparative Examples 1 and 2: Photocurable Resin Compositions

The photocurable resin composition was prepared by combining as shown in Table 1 below, and dropping the photocurable resin composition onto a plasma treated PMMA film using a separate inkjet device to implement a pattern in the form of a microlens, and 700mJ / cm 2. An electrodeless mercury lamp of a light amount of was irradiated to cure the resin layer. The prepared cured resin was evaluated for physical properties according to the evaluation method described in the following Experimental Example, and the results are shown in Table 2.

(Unit: parts by weight) Example Comparative example One 2 3 4 5 6 7 One 2 PETA 30 40 3 60 DPHA 50 40 70 45 M270 50 35 85 0.5 M280 50 50 25 65 IBOA 10 30 M200 15 10 5 5 7 35 40 I-184 5 5 5 5 5 5 4.5 5 5

PETA: Pentaerythritol triacrylate (Miwon Corporation)

DPHA: Dipentaerythritol hexaacrylate (Japanese gunpowder)

M270: polyethylene glycol (4 molar addition) diacrylate (Miwon Corporation)

M280: Polyethylene glycol (9 mol addition) diacrylate (Miwon Corporation)

M200: 1,6-hexanediol diacrylate (Miwon Corporation)

IBOA: isobonol acrylate (Osaka Gas)

I-184: 1-Hydroxy-cyclohexyl-phenyl ketone

Experimental Example

(1) Curability Evaluation

A uniformly mixed coating solution was dropped dropwise onto the plasma-treated PMMA film using a syringe equipped with a 20-gauge syringe needle. To judge.

Good cure ○, Not hard △, Not hard X

(2) color coordinates

The photocurable coating composition was coated on a PMMA film with a 5 μm thickness using a Myerba, and then measured by averaging the color coordinate values of 13 points on the size of the coated film after UV curing. The color coordinate system is CIEI * b *, an international standard, and b *.

(3) adhesion

After the coating was hardened in the same manner as in the above 2, 11 straight lines were drawn on the coated surface of the film at intervals of 1 mm at intervals of 1 mm to make 100 squares, and then three times using a tape (CT-24, manufactured by Nichibang, Japan). Peel test is in progress. Three 100 squares were tested and averaged.

The adhesion is recorded as follows.

Adhesion = n / 100

n: number of rectangles

100: total number of squares

Therefore, if not peeled off at all, record 100/100.

 (4) yellowing

The color coordinates were measured after being left at 80 degrees for 0.3 hours at 0.34 W / m 2 weather-O-meter.

Example Comparative example One 2 3 4 5 6 7 One 2 Curable O O O O O O O O O Early
Color coordinate (b *) 6.8 6.7 6.5 6.8 6.8 7 6.7 15 17 Adhesion 100/100 100/100 100/100 100/100 99/100 100/100 95/100 90/100 90/100 Yellowing (b *) 8.1 8.9 8.5 8.1 8.1 9 8.7 15 20

As can be seen in Tables 1 and 2 above, in Examples 1 to 7, wherein the polyfunctional (meth) acrylate and the hydrophilic (meth) acrylate were added according to the present invention, the polyfunctional (meth) acrylate and the hydrophilic (meth) Compared with Comparative Examples 1 and 2 in which one of the acrylates is not used, it can be seen that not only exhibits excellent physical properties but also particularly has low yellowing property and very good adhesion. In particular, in Examples 1 to 4, in which the polyfunctional (meth) acrylate and the hydrophilic (meth) acrylate are used together in the preferred range according to the present invention, the addition amount thereof is in comparison with Examples 5 to 7, which are outside the preferred range of the present invention. It can be confirmed that better.

Claims (13)

For light guide plate dot formation using an inkjet method comprising a hydrophilic (meth) acrylate represented by the following formula (1), a polyfunctional (meth) acrylate including two or more intramolecular (meth) acrylate groups, and a photoinitiator Photocuring resin composition. [Formula 1]

(In Formula 1, R1 is ethylene or propylene, R2 is a hydrogen atom or a methyl group, Y is a hydrogen atom or an ethylenically unsaturated group or a straight or branched hydrocarbon of 1 to 50 carbon atoms, n is an integer of 1 to 50 .) The method according to claim 1, The said hydrophilic (meth) acrylate is 1-80 weight part with respect to 100 weight part of all photocurable resin compositions, The light-curing plate dot forming photocurable resin composition using the inkjet method characterized by the above-mentioned. The method according to claim 1, The polyfunctional (meth) acrylate in which two or more (meth) acrylate groups are contained in the said molecule | numerator, The viscosity of 1-2000 cps is used, The light-curing-plate dot formation photocurable resin composition using the inkjet method characterized by the above-mentioned. The method according to claim 1, The polyfunctional (meth) acrylate is a light-curing plate dot-forming photocurable resin composition using the inkjet method, characterized in that 5 to 60 parts by weight based on 100 parts by weight of the total photocurable resin composition. The method according to claim 1, The photocuring resin composition for forming a light guide plate dot using the inkjet method, wherein the photoinitiator is one or more selected from the group consisting of benzene ether, benzyl ketal, alpha hydroxy alkyl phenone, and amino alkyl phenone initiators. The method according to claim 1, The photoinitiator is 0.1 to 10 parts by weight based on 100 parts by weight of the total photocurable resin composition, the light-curing plate dot-forming photocurable resin composition using the inkjet method. The method according to claim 1, The viscosity of the said photocurable resin composition is 1-50cps, The photocurable resin composition for light-guide plate dot formation using the inkjet method. The method according to claim 1, The photocurable resin composition for light-guide plate dot formation using the inkjet method characterized by the refractive index of the said photocurable resin composition being 1.4-1.6. A light guide plate comprising a microlens-shaped pattern manufactured by dot-forming and curing the composition of any one of claims 1 to 8 on one or both surfaces of the base film. The method according to claim 9, The base film is a light guide plate, characterized in that selected from polyethylene terephthalate, polycarbonate, polymethyl methacrylate. The method according to claim 9, The base film is a light guide plate characterized in that the plasma treatment on one or both sides. A backlight unit comprising the light guide plate of claim 9. A liquid crystal display device comprising the backlight unit of claim 12.