KR101025796B1 - Patterned light guide plate and improved manufacturing method thereof - Google Patents

Abstract

PURPOSE: A patterned light guide plate and improved manufacturing method thereof are provided to drastically shorten pattern processing time and increase productivity by simplifying processes. CONSTITUTION: A patterned light guide plate comprises a light guide material(100) and a plurality of hemispherical lenses(200). The surface of the light guide material is processed using a reactive gas. The hemispherical lenses are formed of ejected and hardened UV curing compositions. The viscosity of the UV curing compositions is larger than 1cps and smaller than 200cps or larger than 5cps and smaller than 100cps. The adhesive rate and a contact angle of a UV curing composition to the light guide material increase when a reactive gas is used.

Description

Patterned Light Guide Plate And Improved Manufacturing Method Thereof}

The present invention relates to an improved patterned light guide plate for use in display devices and planar lighting devices, and a method of manufacturing the same.

The present invention relates to a pattern light guide plate that can be applied to a backlight unit or a lighting device of various display devices such as a portable terminal, an LCD TV, and the like. Among them, it can be applied to a liquid crystal display (LCD) using an LED light source.

The liquid crystal display of the LED light source is divided into a direct type of attaching the lamp to the back of the display panel and an edge type of attaching to the side of the panel according to the position of attaching the LED lamp. Similarly, planar lighting using LED light source is divided into direct type and edge type.

In the direct type, the lamp is uniformly arranged on the back side to induce uniform light output to the front part, but in the edge type where the lamp is located on the side, the edge shows high brightness but the center part is far from the lamp. The brightness becomes dark. In order to improve this, a light guide plate engraved with a predetermined pattern is attached. The size and density of the pattern are adjusted to uniformly radiate the light emitted from the side part to the front part through the pattern light guide plate.

The pattern light guide plate can be largely divided into silk screen, stamping, injection, laser, and inkjet methods. Of these, the most commonly used method is silk screen, which is commonly used in various applications such as advertisement printing. It is difficult to expect high brightness because the interval is 600 ~ 800μm, and it also has the inconvenience and problem of peeling the pattern when drying hot air after printing and cooling aging after manufacturing. However, in large displays larger than a monitor size, a technology with high yield, which is easily commercially adopted in addition to the inkjet method, has not yet emerged and is the most widely used method.

The stamping method is a method in which a bare light guide plate is made by pressing a stamped pattern with a hot press and is not commercially expanded due to a low yield problem. On the other hand, the injection method is a method of continuously photographing a light guide plate having a pattern of a desired shape using a mold, and is commonly used in small and medium-sized displays such as notebooks, but when the size increases, the cooling time of the injection molding process is increased. It has a problem that productivity is lowered due to long cycle time. Also, when the display area is increased, the pattern light guide plate is distorted due to the thermal history of the molding process after injection molding, which makes it difficult to apply to large-area displays such as TVs. have.

The technology introduced to cope with the large area of the display can be printed on the surface regardless of the area of the light guide plate by the laser method, but this also takes a long time to laser print all the pattern shapes one by one with the low yield problem. It has a long problem that productivity falls. In addition, forming a pattern on a thin light guide substrate to cope with a slim design has a limitation in commercially widening due to the surface heating problem of the light guide plate by a laser.

As each of these manufacturing methods has a productivity problem, a heat generation problem during processing, a thin light guide plate processing problem, and a large area warping problem, the inkjet method has been proposed to improve the problems and achieve high brightness. In the conventional inkjet method, in order to increase the adhesion between the lens forming the pattern and the surface of the light guide plate, a primer coating is applied or an ultraviolet curing composition having intermediate chemical properties between the light guide plate and the lens is applied to a thickness of 1 μm or less, and then ultraviolet curing. Then, the UV curable composition for lens formation is discharged through an inkjet nozzle to make a lens.

However, even if the coating treatment to improve the adhesion of the lens is improved, but still has a problem that does not exhibit sufficient adhesion. In addition, since the primer or ultraviolet curing coating intermediate layer is irradiated with ultraviolet rays, yellowing may occur on the coating layer, thereby affecting the overall chromaticity, and even though a thin coating of 1 μm or less may cause a slight decrease in luminance due to the coating layer. .

The present invention improves productivity by dramatically shortening the pattern processing time by simplifying the process while improving the problems of the conventional inkjet method mentioned above in addition to the problems of silk screen, injection, and laser. An object of the present invention is to provide a method of manufacturing an inkjet patterned light guide plate.

In addition, an object of the present invention is to provide an inkjet method of manufacturing a method of improving the contact angle of a lens such that the lenses forming the pattern of the light guide plate have excellent adhesion and high luminance and uniformity of brightness.

In addition, the improved plasma surface treatment method directly adjusts the contact angle of the UV-curable lens to the light guide substrate, thereby improving the contact angle of the lens to the light guide substrate, and at the same time as the ink is discharged from the inkjet nozzle. An object of the present invention is to provide a patterned light guide plate manufacturing method and a patterned light guide plate for forming a stable hemispherical lens with no large change in contact angle with respect to the light guide substrate.

The patterned light guide plate according to the present invention provided to achieve the above object is a light guide substrate surface-treated with a plasma using a reactive gas consisting of a fluorine-containing gas; as an ultraviolet curing composition discharged and cured on the surface of the light guide substrate It characterized in that it comprises a; a plurality of hemispherical lens formed.

The fluorine-containing gas may be NF ₃ , CF ₄ , SF ₆ , CHF ₃ , C ₂ F ₆ , C ₃ F ₈ , C ₄ F ₈ , PF ₅ , SiF ₄ , WF ₆ , and the like. It is preferable that 1 type, or 2 or more types of mixed gas is used among the containing gas, and the contact rate and the contact angle of the hemispherical lens with respect to the light guide substrate are improved when the reactive gas is used.

In addition, the light guide substrate may be polymethyl methacrylate (PMMA, polymethylmethacrylate) or polycarbonate (PC, polycarbonate) or MS resin (methylmethacrylate-styrene copolymer) or polyethylene terephthalate (PET).

The ultraviolet curing composition is preferably composed of a reactive oligomer, monomer, photoinitiator and other additives.

Herein, the ultraviolet curable composition may have a viscosity at room temperature of 1 cps or more and 200 cps or less, or 5 cps or more and 100 cps or less.

In addition, the reactive oligomer is selected from the group consisting of epoxy acrylate, urethane acrylate, polyester acrylate, unsaturated polyester, polyether acrylate, spirane acrylate, silicone acrylate, polybutadiene acrylate, vinyl acrylate It is preferred to consist of one or more mixtures.

Here, the monomer has a hydrophobic monomer of 50 parts by weight or less in 100 parts by weight of the total monomer, styrene, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, octyl (meth) acrylic Latex, decyl (meth) acrylate, stearyl (meth) acrylate, isobornyl (meth) acrylate, 2-pinoxymethyl (meth) acrylate, 2-pinoxyethyl (meth) acrylate, ethylene glycol Di (meth) acrylate, 1,3-butylene glycol (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, ethoxylated bisphenol A di (meth) acrylate, propoxylated neopentylglycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, tris (2-hydroxyethyl) isocyanurate tri (meth) acrylic Rate It is preferable that at least one selected from the group be included.

In addition, the monomer is hydroxyethyl (meth) acrylate, hydroxymethyl (meth) acrylate, acrylic acid, methacrylic acid, acrylamide, N-vinylpyrrolidone, N-vinylacetamide, N-methyl N-vinylacetamide, 2- (2-ethoxyethoxy) ethyl (meth) acrylate, tetrahydrofuryl (meth) acrylate, polyethylene glycol diacrylate, tetraethylene glycol di (meth) acrylate, triethylene Glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, at least 10 moles of ethoxylated bisphenol A di (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth ) Acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, ethoxylated trimethylolpropane tri (meth) arc Relate, propoxylated trimethylolpropane tri (meth) acrylate, propoxylated glyceryl tri (meth) acrylate, ethoxylated pentaerythritol tri (meth) acrylate, ethoxylated pentaerythrate It is preferable that at least one selected from the group consisting of hydrophilic monomers consisting of lititol tri (meth) acrylate, tetrahydroperfuryl (meth) acrylate and glycerol (meth) acrylate is included.

In order to achieve another object of the present invention, the present invention provides a backlight unit including the pattern 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.

According to another aspect of the present invention, there is provided a method of manufacturing a patterned light guide plate, including: a first step (S100) of activating a surface of a light guide substrate by treating the surface of the light guide substrate with plasma; And a second step (S200) of discharging an ultraviolet curable composition on the surface of the activated light guide substrate by using an inkjet device. And a third step (S300) of curing the ultraviolet curable composition to form a plurality of hemispherical lenses, wherein the fluorine-containing gas NF ₃ , CF ₄ , SF ₆ , or CHF is activated when the surface of the light guide substrate is activated. One or two or more mixed gases of ₃ , C ₂ F ₆ , C ₃ F ₈ , C ₄ F ₈ , PF ₅ , SiF ₄ , and WF ₆ may be used as the reactive gas of the plasma.

Here, the flow rate ratio of the reactive gas and the carrier gas used in the plasma treatment of the first step is preferably 1/5 to 1/1000 or 1/50 to 1/700 or 1/100 to 1/500.

In addition, the light guide substrate is preferably polymethyl methacrylate (PMMA, polymethylmethacrylate) or polycarbonate (PC, polycarbonate) or MS resin (methylmethacrylate-styrene copolymer) or polyethylene terephthalate (PET).

It is preferable that the ultraviolet curable composition is composed of a reactive oligomer, a monomer, a photoinitiator and other additives.

Herein, the ultraviolet curable composition preferably has a viscosity at room temperature of 1 cps or more and 200 cps or less, or 5 cps or more and 100 cps or less.

In addition, the reactive oligomer is selected from the group consisting of epoxy acrylate, urethane acrylate, polyester acrylate, unsaturated polyester, polyether acrylate, spirane acrylate, silicone acrylate, polybutadiene acrylate, vinyl acrylate It is preferably composed of one or more mixtures.

Similarly, the monomer has a hydrophobic monomer of 50 parts by weight or less in 100 parts by weight of the total monomers, and styrene, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate and octyl (meth) acryl Latex, decyl (meth) acrylate, stearyl (meth) acrylate, isobornyl (meth) acrylate, 2-pinoxymethyl (meth) acrylate, 2-pinoxyethyl (meth) acrylate, ethylene glycol Di (meth) acrylate, 1,3-butylene glycol (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, ethoxylated bisphenol A di (meth) acrylate, propoxylated neopentylglycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, tris (2-hydroxyethyl) isocyanurate tri (meth) acrylic Rate Is contained at least one selected from the group true is preferred.

Here, the monomer is hydroxyethyl (meth) acrylate, hydroxymethyl (meth) acrylate, acrylic acid, methacrylic acid, acrylamide, N-vinylpyrrolidone, N-vinylacetamide, N-methyl N-vinylacetamide, 2- (2-ethoxyethoxy) ethyl (meth) acrylate, tetrahydrofuryl (meth) acrylate, polyethylene glycol diacrylate, tetraethylene glycol di (meth) acrylate, triethylene Glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, at least 10 moles of ethoxylated bisphenol A di (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth ) Acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, ethoxylated trimethylolpropane tri (meth) a Acrylate, propoxylated trimethylolpropane tri (meth) acrylate, propoxylated glyceryl tri (meth) acrylate, ethoxylated pentaerythritol tri (meth) acrylate, ethoxylated pentaerythrate It is preferred that at least one selected from the group consisting of hydrophilic monomers consisting of lititol tri (meth) acrylate, tetrahydroperfuryl (meth) acrylate and glycerol (meth) acrylate.

In order to achieve another object of the present invention, the present invention provides a patterned light guide plate formed by the above method.

In accordance with another aspect of the present invention, the present invention provides a backlight unit including the patterned light guide plate.

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

According to the improved method of manufacturing the patterned light guide plate and the patterned light guide plate according to the present invention, the contact angle and the adhesion rate of the hemispherical lens which is much higher than the contact angle obtained in the conventional method of manufacturing the patterned light guide plate using the inkjet method can be obtained and the surface-treated light guide It is possible to improve the disadvantage that the contact angle decreases due to the spreading of ink with the passage of time for several seconds on the surface of the substrate, and thus there is an effect of expressing high luminance and high uniformity of luminance.

In addition, by directly adjusting the contact angle of the UV curable lens to the light guide substrate by the improved plasma surface treatment method, the contact angle of the lens to the light guide substrate is further improved, and at the time after the ink is discharged from the inkjet nozzle, There is an effect that can form a stable hemispherical lens without a large change in the contact angle of the lens to the light guide substrate.

1 is an enlarged view of a patterned light guide plate showing the shape of a hemispherical lens according to the present invention, and
2 is a flowchart illustrating a method of manufacturing a pattern light guide plate according to the present invention.

Hereinafter, a pattern light guide plate and a method of manufacturing the pattern light guide plate according to embodiments of the present invention will be described in detail with reference to the accompanying table and drawings. The following descriptions are for specific examples of the present invention, but are not intended to limit the scope of the rights set forth in the claims, even if there is an assertive or limited expression.

1 illustrates a shape of a hemispherical lens 200 formed on a patterned light guide plate according to the present invention, and FIG. 2 is a flowchart illustrating a method of manufacturing a patterned light guide plate according to the present invention.

 Referring to FIG. 1, the light guide plate according to an embodiment of the present invention is a light guide substrate 100 treated with plasma using a reactive gas composed of a fluorine-containing gas and an ultraviolet curable composition discharged and cured on the surface of the light guide substrate. It is composed of a plurality of hemispherical lens 200 formed as.

Wherein the fluorine-containing gas is NF ₃ , CF ₄ , SF ₆ , CHF ₃ , C ₂ F ₆ , C ₃ F ₈ , C ₄ F ₈ , PF ₅ , SiF ₄ , WF ₆ , and the reactive gas is selected from the fluorine-containing gas. Use one or two or more mixed gases.

In addition, referring to FIG. 2, which illustrates a method of manufacturing a patterned light guide plate illustrated in FIG. 1, in the method of manufacturing a patterned light guide plate according to an exemplary embodiment, the surface of the light guide substrate 100 may be treated with plasma to form a light guide substrate 100. A first step (S100) for activating the surface, and a second step (S200) for discharging the ultraviolet curable composition using the inkjet device on the surface of the activated light guide substrate 100, a plurality of hemispherical lenses by curing the ultraviolet curable composition And a third step (S300) of forming a 200, wherein the activating step is NF ₃ , CF ₄ , SF ₆ , CHF ₃ , C ₂ F ₆ , C ₃ F ₈ , It is characterized by using a fluorine-containing gas such as C ₄ F ₈ , PF ₅ , SiF ₄ , WF ₆ . The hemispherical lens 200 may be formed on one surface or both surfaces of the light guide substrate 100. In the case of forming both sides, both sides are subjected to plasma treatment. The diameter of the hemispherical lens 200 is not limited, preferably 500 μm or less and more preferably 200 μm or less.

The method of manufacturing a patterned light guide plate of the present invention removes organic materials from the surface of the light guide substrate 100 by using a plasma at atmospheric pressure or near atmospheric pressure, activates the surface, and then discharges and cures the ultraviolet curable composition through a nozzle with an inkjet device, thereby curing the light guide substrate. The key is to form a hemispherical lens 200 shape pattern on the (100) surface.

In the prior art, the contact angle of the ink forming the hemispherical lens 200 after the surface treatment of the PMMA light guide substrate is very difficult to obtain more than 50 degrees, and in general, even if the surface treatment is performed, The problem is that the contact angle becomes smaller as time passes for several seconds due to the spreading phenomenon. (Note: If the contact angle between the light guide substrate and the ink does not change with time, for example, 50 °, it is obtained after UV curing of the ink. The contact angle of the hemispherical lens is 50 °.) However, the present inventors have used NF ₃ , CF ₄ , SF ₆ , CHF ₃ , C ₂ F ₆ , C ₃ F ₈ , C ₄ F as a surface treatment method of the light guide substrate 100. _{8, PF 5, SiF 4,} WF 6 , etc. of the fluorine-containing gas by introducing a plasma using a reactive gas was able to significantly improve the above problems and finally to conventional Figure 50 is difficult to achieve the completion of the above pattern light guide panel manufacturing method of obtaining a semi-spherical lens in contact angle.

Here, the “semi-spherical lens contact angle” means a contact angle of the formed hemispherical lens 200 after the hemispherical lens 200 is formed on the light guide substrate 100. Specifically, as shown in Figure 1 below, the ultraviolet curable composition is discharged to the surface of the light guide plate through the inkjet nozzle, and then cured by UV to form a hemispherical lens 200, the lens contact angle is observed by an electron microscope.

<Picture 1>

The fluorine-containing gas used by the present inventors is used in a very small amount, and is generally used by mixing with a carrier gas such as argon, helium or nitrogen, and there is no particular limitation on the type of mixed gas. Depending on the mixing ratio, the characteristics of the plasma-treated surface may vary slightly, and although there is a difference in tendency, the mixing ratio does not impose any limitation on the manufacturing method of the patterned light guide plate.

The flow rate ratio of the conventional reactive gas and the carrier gas is not particularly limited in the range, but is generally 1/5 to 1/1000, preferably 1/50 to 1/700, more preferably 1/100 to 1 / 500. In this case, when the ratio of the carrier gas is 5 or less, there is a disadvantage in that the manufacturing cost increases due to an increase in the content of the reactive gas having a high price even though the surface treatment does not have a large abnormality.

1 illustrates the shape of a hemispherical lens 200 formed on a patterned light guide plate made by a manufacturing method according to an embodiment of the present invention. The position, density, size, etc. of the lens pattern may vary and are not limited.

Since the inkjet method is a non-contact printing method, the adhesion between the ink and the substrate is inferior to that of the contact printing method. As can be seen in the experimental example described below, when the pattern is formed on the light guide substrate 100 by an inkjet method without any special treatment, the adhesion strength is significantly lowered due to the adhesion problem between the ink and the substrate, which leads to a decrease in reliability and durability of the product. .

However, in the present invention, it can also be confirmed that the adhesive strength, which is a quality concern, is improved through plasma surface treatment. Although surface treatment with hydrophobicity, excellent adhesion can be obtained because the surface of the light guide substrate 100 is instantaneously ionized by plasma.

On the other hand, the plasma processing method is well known, the low-temperature plasma processing apparatus can be easily purchased on the market. Basic principles and application examples for plasma are described in the literature. ("Fundamentals of Plasma Chemistry" in "Technology and Application of Plasma Chemistry", by J.R. Holahan and A.T. Bell, Wiley, NY, 1974; H. Suhr, Plasma Chem. Plasma Process 3 (1), 1, 1983). In addition, for low temperature plasma treatment, see “H.J. Jacobasch et al., Farbe + Lack 99 (7), p602, 1993 ”and“ J. Friedrich et al., Surf. It is described in Coating Tech., 59, p371, 1993 ”and the detailed description is omitted.

Preferably, in the present invention, it is preferable to activate the surface of the light guide substrate 100 with a low temperature plasma treatment, in particular, a low temperature plasma at or near atmospheric pressure.

On the other hand, plasma activation using fluorine-containing gases such as NF ₃ , CF ₄ , SF ₆ , CHF ₃ , C ₂ F ₆ , C ₃ F ₈ , C ₄ F ₈ , PF ₅ , SiF ₄ , WF ₆ as a reactive gas Process control methods may vary and are not limited. It is also possible to control the contact angle with the ink by controlling the RF frequency, output, gas flow rate, and the like of the plasma to be processed.

There is no limitation on the kind of the light guide substrate 100. As a preferred example, the light guide substrate 100 includes polymethyl methacrylate (PMMA, polymethylmethacrylate), polycarbonate (PC, polycarbonate), MS resin (methylmethacrylate-styrene copolymer), or polyethylene terephthalate (PET). It is better to use what you do. The light guide substrate 100 may be in the form of a film, an extrusion sheet or a thick plate formed by injection, but is not limited thereto.

Hereinafter, the ultraviolet curing composition will be described. The ultraviolet curable composition can be used without limitation as long as it can satisfy the above conditions. Preferably, the UV curable composition is composed of reactive oligomers, monomers and photoinitiators and other additives. The monomer may be a polyfunctional or monofunctional monomer or a mixture of these monomers.

In particular, the UV-curable composition may have a viscosity at room temperature of 1 cps or more and 200 cps or less, or 5 cps or more and 100 cps or less. Since the ink discharged from the inkjet nozzle, that is, the ultraviolet curable composition, is discharged in volume units of picoliters to control the diameter of the hemispherical lens, the viscosity of the ink has a great influence on the size of the discharged droplets. Should be strictly controlled. UV curing composition using only a monomer has a low viscosity does not have a great difficulty in inkjetting, but in order to form the hemispherical lens 200 of the present invention, the blending ratio should be adjusted so that the viscosity of the final UV curing composition does not exceed 200 cps at room temperature. If the viscosity exceeds 200 cps, it is difficult to discharge the ultraviolet curable composition at room temperature. Even if the viscosity is lowered by heating the inkjet head or forcedly discharged by controlling the piezo-type head, the size of the ejected droplets is increased. It becomes difficult to obtain relatively large or desired uniform size droplets. As a result, the size of the lens cannot be satisfactorily adjusted, making it difficult to implement a desired pattern, which is difficult to expect a satisfactory increase in luminance, and also degrades the uniformity of luminance.
In the present invention, a piezo-type inkjet is used to eject droplets of the ultraviolet curable composition at a very high speed of 20 kHz (20,000 drops / sec) at a position determined according to a pattern determined on the surface of the light guide substrate by the drop-on-demand principle. . In addition, by controlling the wave-form of the pulse at the time of ejection, the shape of the droplets adhering to the substrate surface can be adjusted, and in order to control the size of the lens, a multi-drop technique for discharging several droplets at the same point is applied.

Therefore, in order to implement a pattern on the surface of the light guide substrate 100 by the inkjet method, the viscosity of the ultraviolet curable composition forming the hemispherical lens 200 should be 1 cps or more and 200 cps or less at room temperature. Preferably at room temperature is 5 cps or more and 150 cps or less, More preferably, it is 5 cps or more and 100 cps or less.

The reactive oligomer is preferably selected from epoxy acrylate, urethane acrylate, polyester acrylate, unsaturated polyester, polyether acrylate, spirane acrylate, silicone acrylate, polybutadiene acrylate, vinyl acrylate It is preferably composed of one kind or a mixture of two or more kinds.

There is no particular limitation on the amount of reactive oligomer added to the UV curable composition, but as described above, the dosage should be adjusted so that the room temperature viscosity of the final UV curable composition does not exceed 200 cps. Typical preferred amounts of reactive oligomers for not exceeding 200 cps are up to 50 parts by weight, more preferably up to 40 parts by weight.

The monomer used in the formulation is preferably a UV polymerizable monomer, used as a reactive diluent of the oligomer, and serves to impart the workability of the UV-curable composition, and also polymerizes itself by UV irradiation, and also serves as a crosslinking agent between polymers. Although used for dilution, even though the viscosity is much lower than the reactive oligomer, the trifunctional or higher functional monomer having the advantage of exhibiting a fast curing rate has a viscosity of 200 as the final UV curable composition of the present invention, as shown in Table 1 below. It's higher than cps and you have to be careful about its use.

TABLE 1

In general, various types of hydrophobic and hydrophilic monomers are used alone or in combination in order to adjust properties such as scratch resistance, flexibility, and hardness in the formulation of an ultraviolet curing composition. However, in order to make the contact angle of the hemispherical lens as desired in the present invention to be 40 ° or more, the hydrophobic monomer should be used in a limited manner, and preferably, the hydrophobic monomer does not exceed 50 parts by weight with respect to 100 parts by weight of the monomer. More preferably, it does not exceed 40 parts by weight.

If the hydrophobic monomer exceeds the above range, the contact angle of the lens is reduced, which is undesirable.

The hydrophobic monomer is not particularly limited in its kind, but styrene, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, octyl (meth) acrylate, decyl (meth) acrylate , Stearyl (meth) acrylate, isobonyl (meth) acrylate, 2-pinoxymethyl (meth) acrylate, 2-pinoxyethyl (meth) acrylate, ethylene glycol di (meth) acrylate, 1 , 3-butylene glycol (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, ethoxylated bisphenol A di (meth) acrylate, At least one of propoxylated neopentyl glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate and tris (2-hydroxyethyl) isocyanurate tri (meth) acrylate good .

It is good to use the said monomer independently or using hydrophilic monomer more than hydrophobic monomer at least. The type of hydrophilic monomer can be used without limitation, hydroxyethyl (meth) acrylate, hydroxymethyl (meth) acrylate, acrylic acid, methacrylic acid, acrylamide, N-vinylpyrrolidone, N-vinyl Acetamide, N-methylN-vinylacetamide, 2- (2-ethoxyethoxy) ethyl (meth) acrylate, tetrahydrofuryl (meth) acrylate, polyethylene glycol diacrylate, tetraethylene glycol di (meth ) Acrylate, triethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, at least 10 moles of ethoxylated bisphenol A di (meth) acrylate, pentaerythritol tri (meth) acrylate, Pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, ethoxylated Trimethylolpropane tri (meth) acrylate, propoxylated trimethylolpropane tri (meth) acrylate, propoxylated glyceryl tri (meth) acrylate, ethoxylated pentaerythritol tri (meth) acrylate , At least one of ethoxylated pentaerythritol tri (meth) acrylate, tetrahydroperfuryl (meth) acrylate, and glycerol (meth) acrylate may be used.

The use of a solvent in the present invention can be used as necessary to control the viscosity of the ultraviolet curing composition. The amount used is 0 to 50 parts by weight and preferably 0 to 30 parts by weight. If the viscosity of the ultraviolet curable composition prepared in the present invention does not exceed 200 cps it is not necessary to use a solvent, if it exceeds 200 cps it is necessary to adjust the viscosity down by adding a solvent. The type of solvent is not particularly limited, and any solvent may be used as long as it can control the viscosity of the ultraviolet curing composition downward.

The photoinitiator used in the present invention can also be used alone or a mixture of short-wavelength and long-wavelength initiators without particular limitation on the kind thereof, and any initiator that can cause photodegradation reaction and generate free radicals primarily by ultraviolet irradiation Anything is available. In general, Ciba Specialty Chemical's Igacure, Tarocure Series, Dow Chemical's Syracuse Series, etc. may be used.As a representative example of the short wavelength initiator, Ivacure 184 of Ciba Specialty, and Igacure 819 are used as long wavelength initiators. . Of course, as mentioned above, these can be used individually or in mixture.

The content of the photoinitiator required in the present invention is 0.1 parts by weight to 15 parts by weight relative to the total composition, preferably 0.5 parts by weight to 10 parts by weight, and more preferably 1 part by weight to 6 parts by weight. If the photoinitiator is used in less than 0.1 parts by weight, the curing reaction does not proceed well and it is difficult to obtain a satisfactory UV curable resin. If it is used in excess of 15 parts by weight, the reaction speed is increased, but yellowing of the lens is caused, and the contact angle is decreased. There is a tendency to achieve the desired purpose. Therefore, the dosage of photoinitiator should be used within the given range.

The ultraviolet curable composition obtained in the present invention is easily cured by the usual ultraviolet curing conditions generally used, and there is no particular limitation on the conditions. As long as the light source which is one of the variables which influences a lot in ultraviolet curing can generate an ultraviolet-ray, any one can be used. For example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, a neon lamp, an electrodeless type fusion lamp, etc. can be used. Ultraviolet irradiation conditions vary depending on the respective lamps, but the typical ultraviolet irradiation light amount is about 0.02 J / cm 2 to about 20 J / cm 2, preferably 0.5 J / cm 2 to 10 J / cm 2. This amount of light is not determined as an independent variable, but is closely related to the amount of photoinitiator used, and their determination can be made easily by those skilled in the art of ultraviolet curing. That is, when the deterioration of the substrate is caused by increasing the amount of light, the amount of photoinitiator is increased while lowering the amount of light, and when the yellowing caused by the photoinitiator is generated, the amount of light is increased while lowering the amount of photoinitiator.

The additive is not limited and may additionally include a light absorber (ultraviolet absorber), a photo-sensitizer, an adhesion promoter, an antioxidant, and the like.

The invention can be better understood by the following examples, which are intended for purposes of illustration of the invention and are not intended to limit the scope of protection as defined by the appended claims.

Experimental Example 1.

UV curable inks forming the hemispherical lens 200 include 15 parts by weight of SK Cytec's EBECRYL3702, 10 parts by weight of ethylene glycol dimethacrylate, 10 parts by weight of 2-hydroxyethyl methacrylate, and N-vinylpyrrolidone. 17 parts by weight of dipentaerythritol hexaacrylate, 18 parts by weight of hexanediol diacrylate, 10 parts by weight of isobornyl acrylate, UV curing consisting of 2 parts by weight of photoinitiator Igacure 819 and 3 parts by weight of Igacure 184 The composition was prepared and the viscosity of the composition was 37 cps.

The surface of the light guide substrate mainly composed of polymethyl methacrylate (PMMA) was subjected to a surface treatment while moving the light guide substrate at a speed of 20 mm / sec under the plasma electrode using an atmospheric pressure cold plasma. The RF frequency was 13.56 MHz and the output was 2 KW. The ratio of fluorine-containing gas and carrier gas was 1/300. Argon was used as the carrier gas, and NF ₃ , CF ₄ and SF ₆ was used.

After the plasma surface treatment, using the ink prepared above, lens contact angles according to the presence or absence of plasma treatment and the type of the gas for plasma treatment were measured using the model Phoenix 300 of the SEO company by the sessil drop method. 2 is shown.

TABLE 2

In the case of using argon / oxygen, it can be seen that the contact angle of the lens is slightly increased compared to the untreated treatment. However, in the case of using fluorine-containing reactive gas, the contact angle of the lens is increased to 50 degrees or more. have.

Experimental Example 2.

Using a light guide substrate mainly composed of polycarbonate, the lens contact angle was measured under the same conditions as in Experimental Example 1. The results are shown in Table 3.

TABLE 3

Experimental Example 3.

The ultraviolet curable composition of Experimental Example 1 was discharged to an inkjet apparatus on the plasma surface-treated light guide substrate 100 obtained in Experimental Example 1 to form a hemispherical lens 200, and then cured to a light amount of 3J using a metal halide lamp. . The adhesion rate was then measured and evaluated. At this time, the adhesion rate was carried out according to the cut cut peeling test method shown in JIS K5400, and the number of squares in which the lens remained among 100 squares (1 mm X 1 mm) was counted and expressed as the adhesion rate.

Table 4 below shows the case where the light guide substrate 100 is PMMA. Table 5 shows the results for the case where the light guide substrate 100 is a PC.

TABLE 4

TABLE 5

As a result, it can be seen that the adhesion between M-0 and C-0 without plasma surface treatment is very low. On the other hand, it can be seen that all plasmas exhibit excellent adhesion regardless of the type of gas used.

Comparative Example 1.

In Experimental Example 1, while the content of isobornyl acrylate, which is a hydrophobic monomer, was 30 parts by weight, the content of N-vinylpyrrolidone, which was a hydrophilic monomer, was 10 parts by weight, and 2-hydroxyethyl methacrylate was not used. The results are shown in Table 6.

TABLE 6

It can be seen that the contact angle of the lens decreases considerably with the adhesion rate.

The present invention also provides a backlight unit having the patterned light guide plate and the patterned light guide plate manufactured by the method of manufacturing the patterned 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 may be provided on a light source such as an LED or the upper surface of a patterned light guide plate according to the present invention. In addition, the present invention provides a liquid crystal display device having the backlight unit. The liquid crystal display device is also not limited in structure, and may employ a structure known in the art.

While preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described specific embodiments. That is, those skilled in the art to which the present invention pertains can make many changes and modifications to the present invention without departing from the spirit and scope of the appended claims, and all such appropriate changes and modifications are possible. Equivalents should be considered to be within the scope of the present invention.

100: light guide substrate 200: hemispherical lens

Claims (21)

Fluorine-containing gases such as NF ₃ , CF ₄ , SF ₆ , CHF ₃ , C ₂ F ₆ , C ₃ F ₈ , C ₄ F ₈ , PF ₅ , SiF ₄ , WF _6, etc. A light guide substrate surface-treated with plasma using the configured reactive gas; And,
And a plurality of hemispherical lenses formed as ultraviolet curable compositions discharged and cured on the surface of the light guide substrate.
The UV curable composition has a viscosity of 1 cps or more and 200 cps or less or 5 cps or more and 100 cps or less at room temperature, and when using a reactive gas, the adhesion ratio and contact angle of the hemispherical lens to the light guide substrate are improved. delete The method of claim 1,
The light guide substrate is a patterned light guide plate, characterized in that the polymethyl methacrylate (PMMA, polymethylmethacrylate) or polycarbonate (PC, polycarbonate) or MS resin (methylmethacrylate-styrene copolymer) or polyethylene terephthalate (PET). The method of claim 1,
The ultraviolet curable composition is a patterned light guide, characterized in that consisting of reactive oligomers, monomers, photoinitiators and other additives. delete The method of claim 4, wherein
The reactive oligomer is one selected from the group consisting of epoxy acrylate, urethane acrylate, polyester acrylate, unsaturated polyester, polyether acrylate, spirane acrylate, silicone acrylate, polybutadiene acrylate, vinyl acrylate The patterned light guide plate comprised by the above mixture. The method of claim 4, wherein
The monomer has a hydrophobic monomer of 50 parts by weight or less in 100 parts by weight of the total monomer, styrene, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, octyl (meth) acrylate, Decyl (meth) acrylate, stearyl (meth) acrylate, isobornyl (meth) acrylate, 2-pinoxymethyl (meth) acrylate, 2-pinoxyethyl (meth) acrylate, ethylene glycol di ( Meth) acrylate, 1,3-butylene glycol (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, ethoxylated bisphenol A di With (meth) acrylate, propoxylated neopentylglycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, tris (2-hydroxyethyl) isocyanurate tri (meth) acrylate Group Pattern from the light guide plate, characterized in that includes the selected at least one kind. The said monomer is hydroxyethyl (meth) acrylate, hydroxymethyl (meth) acrylate, an acrylic acid, a methacrylic acid, acrylamide, N-vinylpyrrolidone, N-vinylacetamide. , N-methyl N-vinylacetamide, 2- (2-ethoxyethoxy) ethyl (meth) acrylate, tetrahydrofuryl (meth) acrylate, polyethylene glycol diacrylate, tetraethylene glycol di (meth) acrylic Latex, triethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, at least 10 moles of ethoxylated bisphenol A di (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythrate Lithol Tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, ethoxylated trimethylolpropane (Meth) acrylate, propoxylated trimethylolpropane tri (meth) acrylate, propoxylated glyceryl tri (meth) acrylate, ethoxylated pentaerythritol tri (meth) acrylate, ethoxylay A patterned light guide plate comprising at least one member selected from the group consisting of a hydrophilic monomer consisting of tid pentaerythritol tri (meth) acrylate, tetrahydroperfuryl (meth) acrylate, and glycerol (meth) acrylate. delete delete NF ₃ , CF ₄ , SF ₆ , CHF ₃ , C ₂ F ₆ , C ₃ F ₈ , C ₄ F ₈ , PF ₅ , SiF ₄ , WF ₆ consists of one or two or more mixed gases A first step (S100) of activating a surface of the light guide substrate by treating with plasma by using a reactive gas;
A second step (S200) of discharging an ultraviolet curable composition by using an inkjet device on a surface of the activated light guide substrate; And,
And a third step (S300) of curing the ultraviolet curable composition to form a plurality of hemispherical lenses, wherein the flow rate ratio of the reactive gas and the carrier gas used in the plasma treatment of the first step is 1/5 to 1/1000. Or 1/50 to 1/700 or 1/100 to 1/500, wherein the UV curable composition has a viscosity of 1 cps or more and 200 cps or less or 5 cps or more and 100 cps or less at room temperature, and the hemispherical lens for the light guide substrate when using a reactive gas A method of manufacturing a patterned light guide plate, characterized in that the adhesion rate and contact angle are improved. delete The method of claim 11, wherein the light guide substrate is polymethyl methacrylate (PMMA, polymethylmethacrylate) or polycarbonate (PC, polycarbonate) or MS resin (methylmethacrylate-styrene copolymer), characterized in that the polyethylene terephthalate (PET, polyethyleneterephthalate) Method of manufacturing a patterned light guide plate. 12. The method of claim 11, wherein the ultraviolet curable composition is composed of a reactive oligomer, a monomer, a photoinitiator, and other additives. delete 15. The process of claim 14 wherein the reactive oligomer is epoxy acrylate, urethane acrylate, polyester acrylate, unsaturated polyester, polyether acrylate, spirane acrylate, silicone acrylate, polybutadiene acrylate, vinyl acrylate. A method of manufacturing a patterned light guide plate, characterized in that consisting of one or more mixtures selected from the group consisting of. 15. The monomer of claim 14, wherein the amount of the hydrophobic monomer is 50 parts by weight or less in 100 parts by weight of the total monomers, and styrene, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, and octyl. (Meth) acrylate, decyl (meth) acrylate, stearyl (meth) acrylate, isobornyl (meth) acrylate, 2-pinoxymethyl (meth) acrylate, 2-pinoxyethyl (meth) acrylate , Ethylene glycol di (meth) acrylate, 1,3-butylene glycol (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, Toxylated bisphenol A di (meth) acrylate, propoxylated neopentylglycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, tris (2-hydroxyethyl) isocyanurate tree With (meth) acrylate At least one selected from the group consisting of a manufacturing method of a pattern light guide plate characterized in that it is included. The monomer according to claim 14, wherein the monomer is hydroxyethyl (meth) acrylate, hydroxymethyl (meth) acrylate, acrylic acid, methacrylic acid, acrylamide, N-vinylpyrrolidone, N-vinylacetamide , N-methyl N-vinylacetamide, 2- (2-ethoxyethoxy) ethyl (meth) acrylate, tetrahydrofuryl (meth) acrylate, polyethylene glycol diacrylate, tetraethylene glycol di (meth) acrylic Latex, triethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, at least 10 moles of ethoxylated bisphenol A di (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythrate Lithol Tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, ethoxylated trimethylolpropane Li (meth) acrylate, propoxylated trimethylolpropane tri (meth) acrylate, propoxylated glyceryl tri (meth) acrylate, ethoxylated pentaerythritol tri (meth) acrylate, ethoxyl Laminated pentaerythritol tri (meth) acrylate, tetrahydroperfuryl (meth) acrylate, at least one selected from the group consisting of a hydrophilic monomer consisting of glycerol (meth) acrylate of the patterned light guide plate Manufacturing method. delete delete delete

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