KR20080110151A - Composition for backlight unit optical member of display device and backlight unit optical member - Google Patents

Abstract

A composition for a backlight unit optical member of a display device and a backlight unit optical member are provided to have the improved thermal resistance, a light diffusing property, a light transmissivity, and a durability. A composition for a backlight unit of a display device, and a backlight unit optical member comprises a crystalline resin in which the crystallization temperature is 80‹C or greater as a basic resin. A crystalline resin includes one or more copolymer of a polyethylene resin, a poly propylene resin and a polyester resin.

Description

Composition for backlight unit optical member of display element and backlight unit optical member TECHNICAL FIELD OF BACKLIGHT UNIT OPTICAL MEMBER OF DISPLAY DEVICE AND BACKLIGHT UNIT OPTICAL MEMBER}

The present invention relates to a composition for a backlight unit optical member of a display device and a backlight unit optical member using the same.

Since a display element such as a liquid crystal display device (LCD device) is not a self-luminous element, a separate light emitting device called a backlight unit is required on the back side thereof. Such a backlight unit may be largely divided into an edge type and a direct type. The edge type backlight unit is mainly included in a small display device applied to a computer monitor, and the direct type backlight unit is mainly used in a large display device applied to an LCD TV. Included.

The direct-type backlight unit includes a light source for generating light, a reflector for reflecting light generated from the light source and directing the panel, and an optical member for scattering light generated from the light source and transmitting the light uniformly to the entire panel (for example, Light diffusing plates or light diffusing films).

However, in such a direct type backlight unit, in order to uniformly transmit the light generated from the light source to the entire panel with sufficient light amount, the optical member needs to exhibit excellent light transmittance and light scattering property. In addition, the optical member has sufficient heat resistance to withstand the high heat generated when the light source is turned on, excellent durability (light resistance or impact resistance) to withstand light or external impact generated from the light source for a long time, and temperature due to lighting and turning off of the light source. It is necessary to exhibit excellent bending characteristics such that warpage and wrinkles do not easily occur even if change or moisture absorption occurs.

Various backlight unit optical members have been proposed to satisfy these various characteristics. In particular, recently, a resin substrate formed by using methacryl-based resin or styrene-based resin as a base resin is contained, and a separate light diffusing agent is dispersed in such a resin substrate, or at least one surface of such a resin substrate has an embossed pattern of a predetermined shape. The formed backlight unit optical member is mainly used.

However, such a backlight unit optical member is manufactured using expensive methacrylic resin or styrene resin as a base resin, thereby increasing the manufacturing cost. In addition, since the methacryl resin or the styrene resin itself does not exhibit sufficient impact strength and bending characteristics, the backlight unit optical member also does not exhibit sufficient durability (particularly impact resistance) and bending characteristics.

In addition, the methacryl resin or styrene resin used as a base resin of the said backlight unit optical member is a transparent thermoplastic resin. Therefore, in order for the backlight unit optical member to exhibit excellent light scattering properties, it is necessary to disperse a considerable amount of light diffusing agent separately in a resin substrate formed of a transparent thermoplastic resin, or to form embossed patterns of various shapes on at least one surface of the resin substrate. There is. For this reason, there exists a possibility that the general characteristic of a backlight unit optical member, for example, durability and a curvature characteristic may fall further.

Accordingly, an object of the present invention is to provide a composition for a backlight unit optical member of a display device and a backlight unit optical member using the same, which exhibits excellent bending resistance and durability, together with excellent heat resistance, light scattering property and light transmittance.

Another object of the present invention is to provide a method of using a predetermined crystalline resin to obtain a backlight unit optical member of a display element.

However, technical problems to be achieved by the present invention are not limited to the above-mentioned problems, and other technical problems will be clearly understood by those skilled in the art from the following description.

The present invention provides a composition for a back light unit optical member of a display element comprising a crystalline resin having a crystallization temperature of 80 ° C. or higher as a base resin.

The present invention also provides a backlight unit optical member of a display element comprising a resin substrate containing a crystalline resin having a crystallization temperature of 80 ° C. or higher as a base resin.

The present invention also provides a method of using a crystalline resin having a crystallization temperature of 80 ° C. or higher as a base resin of a backlight unit optical member of a display element.

In addition, the present invention provides a backlight unit of a display device including the optical member.

The present invention also provides a display device comprising the backlight unit.

Other specific details of the embodiments of the present invention are included in the following detailed description.

Hereinafter, embodiments of the present invention will be described in detail. However, this is presented as an example, by which the present invention is not limited and the present invention is defined only by the scope of the claims to be described later.

First, throughout the present specification, the "resin base material" is defined as a generic term for a resin molded article which forms a resin matrix and forms a basic shape of the backlight unit optical member of the display element. For example, when the optical member is composed of a single resin layer, the "resin base material" refers to such a single resin layer, and when each of the plurality of resin layers constituting the resin matrix is "resin base material", It is interpreted generically as strata. At this time, the light diffusing agent and other additives which do not participate in forming the resin matrix and are dispersed or contained in the single or plural resin layers are interpreted as not belonging to the "resin base material".

In addition, throughout the present specification, the "base resin" refers to a polymer material which is included in a ratio of 50% by weight or more, preferably 70% by weight or more, based on the total weight of the material forming the "resin base material" of the optical member. It is defined as referring. For example, when the "resin base" of the optical member consists of a mixture or copolymer of two or more kinds of polymers, of these two or more kinds of polymers, it is 50 to the total weight of the mixture or copolymer forming the "resin base". One kind of polymer contained in a proportion of at least% by weight, preferably at least 70% by weight is interpreted as "base resin".

Meanwhile, according to one embodiment of the present invention, a method of using a crystalline resin having a crystallization temperature of 80 ° C. or more as a base resin of a backlight unit optical member of a display element is provided. That is, the novel use of the said crystalline resin which uses crystalline resin whose crystallization temperature is 80 degreeC or more as a base resin of the resin base material of the said optical member is not methacryl resin or styrene resin.

As described above, as the optical member is manufactured using a predetermined crystalline resin as a base resin, various characteristics of the optical member can be further improved based on the following principle.

First, representative crystalline resins having a crystallization temperature of 80 ° C or higher include polyethylene resin (crystallization temperature: approximately 110 ° C), polypropylene resin (crystallization temperature: approximately 110 ° C) or polyester resin (crystallization temperature: approximately 160 ° C). Although these crystalline resins are comparatively inexpensive compared with methacrylic resin or styrene resin. Therefore, using this as a base resin can reduce the manufacturing cost of the optical member.

In addition, in a display element such as a liquid crystal display device, the backlight unit can generate high heat with continuous lighting of the light source. For this reason, the optical member needs to exhibit sufficient heat resistance to withstand a long time even in a high temperature environment of about 60-70 ° C. However, since the optical member is provided using a crystalline resin having a crystallization temperature of 80 ° C. or higher as a base resin, the optical member exhibits excellent heat resistance that can withstand a long period of time without a change in crystallinity and general characteristics even in a high temperature environment in a display element. do.

In addition, the crystalline resin having a crystallization temperature of 80 ° C. or higher shows higher impact strength than methacryl resin or styrene resin, and has a higher heat deflection temperature, thereby causing a temperature change or moisture absorption. Even if the warp or wrinkles do not occur well shows excellent bending characteristics. For example, methacryl resin (polymethyl methacrylate resin: 1.6-2.7 kgcm / cm) or styrene resin (polystyrene resin: approximately 2.0 kgcm / cm) is at least 1.6 kgcm at 23 ° C. polypropylene resin (2.2-5.4 kgcm / cm) or polyethylene resin (low density polyethylene resin: substantially impact on the No cracking caused by crystalline resin such as high density polyethylene resin: 2.7-109 kg · cm / cm) has a high impact strength of at least 2.2 kg · cm / cm up to 100 kg · cm / cm. In addition, methacryl-based resin (polymethyl methacrylate resin: 80-105 ° C) or styrene-based resin (polystyrene resin: approximately 100 ° C) shows a heat bending temperature of at least 80 ℃ to 105 ℃, the polypropylene Crystalline resins such as resins (90-150 ° C.) exhibit high thermal bending temperatures above 150 ° C. maximum. Therefore, by manufacturing the optical member using such a crystalline resin as a base resin, the durability (impact resistance) and warpage characteristics of the optical member can be greatly improved.

In addition, the crystalline resin may at least partially crystallize at a predetermined temperature or more, and thus exhibit light scattering properties to some extent (at this time, by adjusting the treatment temperature or thickness of the crystalline resin, etc. Light scattering can be controlled). Therefore, by using the crystalline resin as a base resin, even if the separate light diffusing agent is not dispersed or separately formed embossing pattern, the resin substrate itself of the optical member can be formed to some extent light scattering properties. Therefore, the amount of the light diffusing agent dispersed in the resin substrate or the degree of forming the embossing pattern on the resin substrate can be greatly reduced, and further, the light scattering property is appropriate without the dispersion of the light diffusing agent or the formation of the embossing pattern. And an optical member exhibiting light transmittance. Accordingly, since the overall characteristics of the optical member are less likely to be lowered by the dispersion of the light diffusing agent or the formation of the embossing pattern, the improved overall characteristics, for example, durability or the like, may be maintained while maintaining excellent light scattering and light transmittance. An optical member exhibiting bending characteristics can be provided.

On the other hand, as the crystalline resin having a crystallization temperature of 80 ° C. or more, a polyethylene resin, a polypropylene resin, or a polyester resin may be used, or two or more copolymers or mixtures selected therefrom may be used. In addition, as the polyethylene resin, a low density polyethylene resin or a high density polyethylene resin, a copolymer or a mixture thereof can be used without limitation, and as the polypropylene resin, a polypropylene resin in the form of a homo, block or random polymer can be used without limitation. . In addition to these resins, any crystalline resin having a crystallization temperature of 80 ° C or higher can be used without limitation.

In addition, the crystalline resin may have a weight average molecular weight of less than 100000, preferably have a weight average molecular weight of 1000 to 100000. And it is preferable that the said crystalline resin shows the melting temperature of 100 degreeC or more.

The crystallized resin having the weight average molecular weight and the melting temperature is easy to process and exhibits an appropriate crystallization temperature, crystallization rate and melting temperature. Therefore, it is easy to control the temperature and thickness of such crystalline resin and to control the degree of crystallization in an appropriate range. Therefore, by controlling the degree of crystallization of the resin substrate of the optical member in an appropriate range using a crystalline resin exhibiting such physical properties, an optical member exhibiting desirable light scattering properties and light transmittance can be easily manufactured. In addition, as the crystalline resin exhibits a melting temperature of 100 ° C. or more, the optical member provided by using the crystalline resin as a base resin has more excellent heat resistance.

The crystalline resin can be used without limitation as a base resin of any backlight unit optical member in substantially all non-luminous display elements. For example, the crystalline resin may be used in an optical member such as a backlight reflector, a backlight unit light diffusion plate, or a backlight unit light diffusion film included in a non-light emitting display element such as a liquid crystal display device, and various kinds of backlights. It can be used without limitation in the unit optical member.

On the other hand, according to another embodiment of the invention, there is provided a composition for a back light unit optical member of a display element comprising a crystalline resin having a crystallization temperature of 80 ℃ or more as a base resin.

The composition for an optical member includes, as a base resin for forming the resin substrate of the backlight unit optical member, the crystalline resin exhibiting appropriate crystallinity and heat resistance together with high impact strength and thermal bending temperature. Therefore, by using the composition for an optical member, it is possible to manufacture a backlight unit optical member exhibiting various properties such as improved durability and warpage characteristics while maintaining excellent heat resistance, light scattering property and light transmittance.

The optical member composition may include only the basic resin of the crystalline resin as a material for forming the resin substrate of the optical member, but may include a mixture of the basic resin and other high molecular materials or a copolymer thereof. have. In this case, the other polymer material mixed or copolymerized with the base resin may be any polymer material previously used to form the resin substrate of the backlight unit optical member, for example, methacryl resin, styrene resin, or polycarbonate. 1 or more types, such as system resin, can be used. However, even in this case, it is obvious that the base resin, that is, the crystalline resin is included in a ratio of 50% by weight or more, preferably 70% by weight or more, based on the total weight of the material for forming the resin substrate of the optical member. .

In addition, as the crystalline resin contained in the optical member composition, a polyethylene resin, a polypropylene resin or a polyester resin may be used, or two or more copolymers or mixtures selected from them may be used. In addition, as the polyethylene resin, a low density polyethylene resin or a high density polyethylene resin, a copolymer or a mixture thereof can be used without limitation, and as the polypropylene resin, a polypropylene resin in the form of a homo, block or random polymer can be used without limitation. . In addition to these resins, any crystalline resin having a crystallization temperature of 80 ° C or higher can be used without limitation.

And, the crystalline resin may have a weight average molecular weight of less than 100000, preferably may have a weight average molecular weight of 1000 to 100000. And it is preferable that the said crystalline resin shows the melting temperature of 100 degreeC or more.

As the composition for an optical member includes a crystalline resin exhibiting such physical properties, an optical member exhibiting desirable light scattering properties and light transmittance can be easily manufactured using the composition. In addition, as the crystalline resin exhibits a melting temperature of 100 ° C. or more, the optical member made of the optical member composition exhibits more excellent heat resistance.

On the other hand, the composition for the optical member may be substantially made of only the base resin of the crystalline resin, or may be made of only a material for forming the resin substrate of the optical member including such a base resin, a light diffusing agent separately from these materials It may further include. That is, when it is difficult to obtain an optical member exhibiting sufficient light scattering property and light transmittance by adjusting only the degree of crystallization of the crystalline resin (for example, in order to obtain a very thin optical member, only crystallizing the crystalline resin It may be difficult to obtain an optical member that exhibits sufficient light scattering property.), And by including a separate light diffusing agent to be dispersed in the resin substrate of the optical member, it is possible to impart additional light scattering properties to the optical member.

Such a light diffusing agent may be included in the composition for the optical member in a ratio of 0.1 to 30 parts by weight based on 100 parts by weight of the base resin, that is, the crystalline resin. In addition, the light diffusing agent may have an average particle diameter of 0.1 to 50μm. By appropriately adjusting the content ratio and the average particle diameter of the light diffusing agent within this range, an optical member exhibiting desirable light scattering properties and light transmittance can be obtained using the composition for optical members.

As the light diffusing agent, for example, an organic light diffusing agent such as a silicon light diffusing agent such as a siloxane light diffusing agent, an acrylic light diffusing agent, a teflon light diffusing agent or a styrene light diffusing agent may be used. It is also possible to use a mixture of two or more selected from these. As the light diffusing agent, for example, inorganic light diffusing agents such as calcium carbonate, barium sulfate, titanium dioxide, aluminum hydroxide, silica, glass, talc, mica, white carbon, magnesium oxide or zinc oxide may be used. It is also possible to use a mixture of two or more selected from these. In addition to the organic or inorganic light diffusing agents listed above, any organic or inorganic light diffusing agent known to be usable for the backlight unit optical member can be used without limitation.

In addition to the above components, the composition for an optical member may include a UV absorber, an antistatic agent, a light stabilizer, a blowing agent, a plasticizer, an antioxidant, a heat stabilizer, a lubricant, a flame retardant, a filler, a release agent, a dye, a pigment, an antibacterial agent, an antidropping agent, and a nucleus. It may further comprise one or more additives selected from the group consisting of zeros. As each of these additives, all conventional materials used in the backlight unit optical member may be used. In addition, each of these additives is included in an appropriate amount that can exhibit a desired action without deteriorating the overall characteristics of the optical member, depending on the use or properties of the optical member to be prepared in the optical member composition.

For example, the antistatic agent may be etherimideamide, polyetherester, polyetheresteramide, polyalkylene glycol or dodecyl benzenesulfonic acid alkali metal, tertiary amine, quaternary ammonium, salt or alkyl amine compound. It can be used, such an antistatic agent may be included in the ratio of 0.001-10 parts by weight with respect to 100 parts by weight of the crystalline resin. In addition, as the ultraviolet absorber, any material capable of absorbing light having a wavelength of 250-800 nm, for example, a benzophenone-based, benzotriazole-based, cyanoacrylate-based, sarithyreto-based or nickel complex salt-based ultraviolet absorber Without limitation, such ultraviolet absorbers may be included in a ratio of 0.01-2 parts by weight based on 100 parts by weight of the crystalline resin.

On the other hand, the above-described composition for an optical member can be used to manufacture any backlight unit optical member in substantially all non-light emitting display elements. For example, the composition for an optical member may be used for an optical member such as a backlight unit reflector, a backlight unit light diffusion plate, or a backlight unit light diffusion film included in a non-light emitting display element such as a liquid crystal display element, and various other types. The backlight unit can be used without limitation in the optical member.

According to another embodiment of the invention, there is provided a backlight unit optical member of a display element comprising a resin substrate containing a crystalline resin having a crystallization temperature of 80 ° C. or more as a base resin.

Such an optical member includes a main material constituting the resin substrate, that is, a base resin, and a predetermined crystalline resin exhibiting appropriate crystallinity and heat resistance with high impact strength and thermal bending temperature. Accordingly, the optical member may exhibit various properties such as improved durability and warpage characteristics while maintaining excellent heat resistance, light scattering property, and light transmittance.

On the other hand, the resin substrate of the optical member may be made of only the base resin of the crystalline resin, but may be formed by forming a resin matrix together with the base resin and the other polymer material. In this case, the other polymer material forming the resin matrix together with the base resin may be, for example, one or more kinds of methacrylic resins, styrene resins, polycarbonate resins, and the like, and in addition, the resin substrate of the backlight unit optical member. It may be of any polymer material applied to. However, even in this case, it is obvious that the base resin of the crystalline resin is included in a ratio of 50% by weight or more, preferably 70% by weight or more, based on the total weight of the material forming the resin substrate of the optical member.

In addition, the resin substrate of the optical member may have a thickness of 100 to 15000μm.

As the crystalline resin constituting the resin substrate of the optical member, a polyethylene resin, a polypropylene resin or a polyester resin may be used, or two or more copolymers or mixtures selected therefrom may be used. In addition, as the polyethylene resin, a low density polyethylene resin or a high density polyethylene resin, a copolymer or a mixture thereof can be used without limitation, and as the polypropylene resin, a polypropylene resin in the form of a homo, block or random polymer can be used without limitation. . In addition to these resins, any crystalline resin having a crystallization temperature of 80 ° C or higher can be used without limitation.

In addition, the crystalline resin may have a weight average molecular weight of less than 100000, preferably have a weight average molecular weight of 1000 to 100000. And it is preferable that the said crystalline resin shows the melting temperature of 100 degreeC or more.

As the crystalline resin exhibits such physical properties, light scattering properties and light transmittance of the optical member are easily controlled appropriately, and the optical member exhibits more excellent heat resistance that can withstand a long time even in a high temperature environment in a display element.

On the other hand, the optical member may consist essentially of a resin substrate containing the basic resin, but may further include a light diffusing agent uniformly dispersed in such a resin substrate. That is, when only the resin substrate itself of the optical member exhibits desirable light scattering properties and light transmittance only by adjusting the degree of crystallization of the crystalline resin which is the basic resin, the optical member may be made of only the resin substrate. However, when the resin substrate hardly exhibits a desired level of light scattering property and light transmittance only by adjusting the degree of crystallization of the crystalline resin due to the treatment temperature or the limitation of the thickness in the manufacturing process of the optical member, the optical member is A light diffusing agent dispersed in the resin substrate may be further included to exhibit desirable light scattering properties and light transmittance.

Such light diffusing agents may have an average particle diameter of 0.1 to 50 μm. Within this range, the average particle diameter of the light diffusing agent may be appropriately adjusted so that the optical member may exhibit desirable light scattering properties and light transmittance.

As the light diffusing agent, for example, organic light diffusing agents such as silicon light diffusing agents such as siloxane light diffusing agents, acrylic light diffusing agents, teflon light diffusing agents, or styrene light diffusing agents may be used. It is also possible to use a mixture of two or more selected from these. As the light diffusing agent, for example, inorganic light diffusing agents such as calcium carbonate, barium sulfate, titanium dioxide, aluminum hydroxide, silica, glass, talc, mica, white carbon, magnesium oxide or zinc oxide may be used. It is also possible to use a mixture of two or more selected from these.

In addition, when the optical member needs to exhibit improved light scattering property, an embossing pattern having a predetermined shape may be formed on at least one surface of the resin substrate. In this case, in order for the optical member to exhibit higher light scattering property, the embossing pattern may be an amorphous pattern having a random shape. In addition, in order for the optical member to have a higher light scattering property and to prevent visible light rays generated from the light source of the backlight unit, the embossing pattern is preferably an amorphous pattern having an average roughness of 0.1 to 10 μm.

Such an embossing pattern can be formed by processing at least one surface of the resin substrate by various methods such as press working, processing after UV resin coating, or polishing roll processing.

On the other hand, the above-described optical member may be made of a single resin layer, but a separate resin layer (coating layer) may be applied to one side or both sides of the basic resin layer (base layer) to form a plurality of resin layers as a whole. In this case, the same or different kinds of light diffusing agents and other additives may be included (dispersed) in the base layer and the coating layer, respectively, and an embossing pattern may be formed on the coating layer to improve light scattering properties.

Further, the above-described optical member can be applied as any backlight unit optical member in substantially all non-light emitting display elements. For example, the optical member may be an optical member such as a backlight unit reflector, a backlight unit light diffuser, or a backlight unit light diffuser film included in a non-light emitting display element such as a liquid crystal display element, and various kinds of backlights. It may be a unit optical member.

In addition, the optical member described above may be manufactured by various methods, such as injection molding, extrusion molding, vacuum molding, hot press molding, or coextrusion molding, in consideration of specific uses, sizes, or thicknesses. .

Of these, by using the extrusion molding, not only an optical member made of a single resin layer, but also an optical member made of a plurality of resin layers can be easily manufactured.

On the other hand, according to another embodiment of the invention, there is provided a backlight unit of a display element comprising the optical member described above. In addition, a display element including such a backlight unit is also provided.

Hereinafter, the configuration and operation of the invention through the preferred embodiment will be described in more detail.

<Example 1>

To 100 parts by weight of polypropylene resin, 2 parts by weight of a silicon light diffusing agent (GE Toshiba Silicone Co., Ltd.) having an average particle diameter of 2 μm and 2 parts by weight of an acrylic light diffusing agent (Sekisui Co., Ltd.) having an average particle diameter of 8 μm were added. The first composition was prepared.

To 100 parts by weight of polypropylene resin, 10 parts by weight of an acrylic light diffusing agent (Sekisui) having an average particle diameter of 30 µm, 1 part by weight of an antistatic agent, and 1 part by weight of an optical stabilizer were added to prepare a second composition. .

Each of the first composition and the second composition was put into an extruder, melted and kneaded, and then fed to a feed block die, whereby the total thickness of the first composition was 2000 μm, except that the first composition had a curing thickness of 1800 μm, A light diffusion plate having a thickness of 100 μm was applied to both surfaces thereof.

Comparative Example 1

Styrene-based resin (PS JAPAN Co., Ltd.) was used instead of polypropylene resin for the preparation of the first composition, and methyl methacrylate-based resin and styrene-based resin were copolymerized instead of the polypropylene resin for the preparation of the second composition. A light diffusing plate was manufactured in the same manner as in Example 1 except that (DENKA Co., Ltd.) was used.

Comparative Example 2

For the preparation of the first composition, a light diffusion plate was manufactured in the same manner as in Comparative Example 1 except for using a resin (DENKA Co., Ltd.) copolymerized with methyl methacrylate resin and styrene resin instead of styrene resin.

The physical properties of the light diffusion plates of Example 1, Comparative Examples 1 and 2 were evaluated by the following method, and the evaluation results are shown in Table 1 below.

(1) light resistance test

After irradiating ultraviolet rays for 72 hours at a temperature of 60 ℃ using ATLAS-UVCON, the amount of YI (Yellow Index) change of each light diffusion plate was measured.

(2) Light transmittance and light scattering test

The light transmittance and the light scattering property of each light diffusing plate were measured with a haze meter (NDH 5000W, Nippon Denshi Kogyo Co., Ltd.).

(3) luminance test

Each light diffuser was mounted on a 46-inch backlight and measured using a BM-7 luminance meter.

(4) visibility

Each light diffusing plate was mounted in a 32-inch backlight, and the cold cathode fluorescent lamp concealment was visually observed, and the visibility was evaluated in two stages of visibility and failure of the cold cathode fluorescent lamp.

TABLE 1

division Example 1 Comparative Example 1 Comparative Example 2 Light resistance (△ YI) 7 15 9 Light transmittance (%) 60.1 53.5 56.7 Light Scattering (%) 93.2 93.0 92.8 Luminance (cd / m ² ) 11,120 11,135 11,140 Visibility Good Good Good

Referring to Table 1, the light diffusing plate of Example 1 has an optical property such as light transmittance, light scattering property, brightness and visibility, is equal to or better than that of the light diffusing plates of Comparative Examples 1 and 2, and further improved durability. It was confirmed that (light resistance) was shown.

In addition, the light diffusing plates of Example 1, Comparative Examples 1 and 2 include the same content of the light diffusing agent and additives, the light diffusing plate of Example 1 has a basic impact strength (2.2-5.4kgcm / cm) and the thermal bending temperature (225-250 ℃) was produced using a higher polypropylene resin, it was confirmed that exhibits improved durability (impact resistance) and bending characteristics compared to the light diffusing plates of Comparative Examples 1 and 2 It became.

In addition, since the light diffusion plate of Example 1 is made of a polypropylene resin having a crystallization temperature of 110 ° C. and a melting temperature of 130 ° C. or more, the crystallization and general characteristics of the light diffusing plate are maintained even in a high temperature environment (approximately 60-70 ° C.) in the display device. It was confirmed to exhibit excellent heat resistance that can withstand long periods without change.

<Example 2>

A first composition including 100 parts by weight of polypropylene resin was prepared.

To 100 parts by weight of polypropylene resin, 1 part by weight of the antistatic agent and 1 part by weight of the light stabilizer were added to prepare a second composition.

The first composition and the second composition were each fed into an extruder, melted and kneaded, and then fed to a feed block die. A lenticular with a pitch of 300 μm and a height of 150 μm was formed on the upper surface by a polishing roll, and a diffuse reflection pattern having an average roughness of 0.8 μm was formed on the lower surface, so that a total thickness of 2000 μm was used. And a second composition was allowed to be applied on both sides of the first composition at a thickness of 200 μm, respectively.).

<Example 3>

A light diffusion plate was manufactured in the same manner as in Example 2 except that a lenticular having a pitch of 400 μm and a height of 150 μm was formed on the upper surface by a polishing roll.

<Example 4>

A light diffusion plate was manufactured in the same manner as in Example 2 except that a lenticular having a pitch of 500 µm and a height of 150 µm was formed on the upper surface by a polishing roll.

Comparative Example 3

To 100 parts by weight of methyl methacrylate resin (Mitsubishi Rayon), 2 parts by weight of a silicon light diffusing agent (GE Toshiba Silicon Co., Ltd.) having an average particle diameter of 2 μm, and an acrylic light diffusing agent having an average particle diameter of 8 μm (Sekisui) 2 parts by weight of 社) was added to prepare a first composition.

1 part by weight of an antistatic agent and 1 part by weight of an optical stabilizer were added to 100 parts by weight of a resin (DENKA Co., Ltd.) copolymerized with a methyl methacrylate resin and a styrene resin to prepare a second composition.

Each of the first composition and the second composition was put into an extruder, melted and kneaded, and then fed to a feed block die, whereby the total thickness of the first composition was 2000 μm, except that the first composition had a curing thickness of 1800 μm, A light diffusion plate having a thickness of 100 μm was applied to both surfaces thereof.

<Comparative Example 4>

For the preparation of the first composition, a light diffusion plate was manufactured in the same manner as in Comparative Example 3 except that styrene resin (PS JAPAN) was used.

The physical properties of the light diffusion plates of Examples 2 to 4 and Comparative Examples 3 and 4 were evaluated by the following methods, and the evaluation results are shown in Table 2 below.

(1) light resistance test

After irradiating ultraviolet rays for 72 hours at a temperature of 60 ℃ using ATLAS-UVCON, the amount of YI (Yellow Index) change of each light diffusion plate was measured.

(2) Light transmittance and light scattering test

The light transmittance and the light scattering property of each light diffusing plate were measured with a haze meter (NDH 5000W, Nippon Denshi Kogyo Co., Ltd.).

(3) luminance test

Each light diffuser was mounted on a 32-inch backlight, and measured using a BM-7 luminance meter.

(4) visibility

Each light diffusing plate was mounted in a 32-inch backlight, and the cold cathode fluorescent lamp concealment was visually observed, and the visibility was evaluated in two stages of visibility and failure of the cold cathode fluorescent lamp.

TABLE 2

division Example 2 Example 3 Example 4 Comparative Example 3 Comparative Example 4 Light resistance (△ YI) 6 6 6 5 15 Light transmission 54.1% 60.7% 65.2% 62.3% 53.2% Light scattering 93.1% 92.4% 90.7% 92.9% 93.1% Luminance 11,312 cd / m ² 11,373 cd / m ² 11,425 cd / m ² 11,141 cd / m ² 11,127 cd / m ² Visibility Good Good Good Good Good

Referring to Table 2, the light diffusing plates of Examples 2 to 4 are light-transmitting, light-scattering, luminance and visibility, without including a separate light diffusing agent dispersed in the resin substrate, Comparative Example It was found to be equivalent to or rather superior to the light diffusing plates of 3 and 4, as well as exhibiting improved durability (light resistance).

In addition, the light diffusing plates of Examples 2 to 4 do not include a light diffusing agent, and have a higher basic impact strength (2.2-5.4 kgcm / cm) and a higher thermal bending temperature (225-250 ° C). Since it was manufactured using a resin, it was confirmed to exhibit improved durability (impact resistance) and warpage characteristics compared to the light diffusion plates of Comparative Examples 3 and 4.

In addition, since the light diffusion plates of Examples 2 to 4 are made of a polypropylene resin having a crystallization temperature of 110 ° C. and a melting temperature of 130 ° C. or higher, crystallinity and generality are maintained even in a high temperature environment (approximately 60-70 ° C.) in a display device. It was confirmed that it exhibits excellent heat resistance that can withstand a long period of time without a change in properties.

Example 5

To 100 parts by weight of polypropylene resin, 0.2 part by weight of a titanium dioxide light diffusing agent having an average particle diameter of 0.5 µm was added to prepare a first composition.

To 100 parts by weight of polypropylene resin, 0.2 part by weight of a titanium dioxide light diffusing agent having an average particle diameter of 0.5 µm, 1 part by weight of an antistatic agent, and 1 part by weight of an optical stabilizer were added to prepare a second composition.

Each of the first composition and the second composition was put into an extruder, melted and kneaded, and then fed to a feed block die, whereby the total thickness of the first composition was 2000 μm, except that the first composition had a curing thickness of 1800 μm, A light diffusion plate having a thickness of 100 μm was applied to both surfaces thereof.

<Example 6>

To 100 parts by weight of polypropylene resin, 1 part by weight of a talc light diffusing agent having an average particle diameter of 0.7 µm was added to prepare a first composition.

To 100 parts by weight of polypropylene resin, 1 part by weight of talc light diffusing agent having an average particle diameter of 0.7 μm, 1 part by weight of an antistatic agent, and 1 part by weight of an optical stabilizer were added to prepare a second composition.

Each of the first composition and the second composition was put into an extruder, melted and kneaded, and then fed to a feed block die, whereby the total thickness of the first composition was 2000 μm, except that the first composition had a curing thickness of 1800 μm, A light diffusion plate having a thickness of 100 μm was applied to both surfaces thereof.

<Example 7>

To 100 parts by weight of polypropylene resin, 2 parts by weight of a calcium carbonate light diffusing agent having an average particle diameter of 0.3 μm was added to prepare a first composition.

To 100 parts by weight of polypropylene resin, 2 parts by weight of a calcium carbonate light diffusing agent having an average particle diameter of 0.3 μm, 1 part by weight of an antistatic agent, and 1 part by weight of an optical stabilizer were added to prepare a second composition.

Each of the first composition and the second composition was put into an extruder, melted and kneaded, and then fed to a feed block die, whereby the total thickness of the first composition was 2000 μm, except that the first composition had a curing thickness of 1800 μm, A light diffusion plate having a thickness of 100 μm was applied to both surfaces thereof.

The physical properties of the light diffusion plates of Examples 5 to 7 were evaluated by the following method, and the evaluation results are shown in Table 3 below in comparison with the light diffusion plates of Comparative Examples 1 and 2.

(1) light resistance test

After irradiating ultraviolet rays for 72 hours at a temperature of 60 ℃ using ATLAS-UVCON, the amount of YI (Yellow Index) change of each light diffusion plate was measured.

(2) Light transmittance and light scattering test

The light transmittance and the light scattering property of each light diffusing plate were measured with a haze meter (NDH 5000W, Nippon Denshi Kogyo Co., Ltd.).

(3) luminance test

Each light diffuser was mounted on a 46-inch backlight and measured using a BM-7 luminance meter.

(4) visibility

Each light diffusing plate was mounted in a 32-inch backlight, and the cold cathode fluorescent lamp concealment was visually observed, and the visibility was evaluated in two stages of visibility and failure of the cold cathode fluorescent lamp.

TABLE 3

division Example 5 Example 6 Example 7 Comparative Example 1 Comparative Example 2 Light resistance (△ YI) 7 7 7 15 9 Light transmittance (%) 59.1 61.9 60.7 53.5 56.7 Light Scattering (%) 93.1 94.8 93.6 93.0 92.8 Luminance (cd / m ² ) 11,115 11,085 11,055 11,135 11,140 Visibility Good Good Good Good Good

Referring to Table 3, the light diffusing plates of Examples 5 to 7 contain a small amount of an inorganic light diffusing agent and have optical characteristics such as light transmittance, light scattering property, brightness, and visibility, respectively. It has been found to be equivalent to or rather superior to the plate and to exhibit improved durability (light resistance).

In addition, the light diffusing plates of Examples 5 to 7 are manufactured by using a polypropylene resin having a higher basic impact strength (2.2-5.4 kg · cm / cm) and a thermal bending temperature (225-250 ° C.). It was confirmed to exhibit improved durability (impact resistance) and warpage characteristics compared to the light diffusion plates of Comparative Examples 1 and 2.

In addition, since the light diffusion plates of Examples 5 to 7 are made of a polypropylene resin having a crystallization temperature of 110 ° C. and a melting temperature of 130 ° C. or higher, crystallinity and generality are maintained even in a high temperature environment (approximately 60-70 ° C.) in a display device. It was confirmed that it exhibits excellent heat resistance that can withstand a long period of time without a change in properties.

According to the present invention, there is provided a backlight unit optical member of a display element which maintains excellent heat resistance, light scattering property and light transmittance, and which has low manufacturing cost and exhibits various characteristics such as improved durability (impact resistance or light resistance) and warpage characteristics. Can be.

Claims (20)

A composition for a backlight unit optical member of a display element comprising a crystalline resin having a crystallization temperature of 80 ° C. or higher as a base resin. The optical member composition of claim 1, wherein the crystalline resin comprises one resin, two or more copolymers or mixtures selected from the group consisting of polyethylene resin, polypropylene resin, and polyester resin. The optical member composition of claim 1, wherein the crystalline resin has a weight average molecular weight of 1000 to 100000. The optical member composition of claim 1, wherein the crystalline resin exhibits a melting temperature of 100 ° C or higher. The composition for an optical member according to claim 1, which is used for the manufacture of a backlight unit reflector, a backlight unit light diffuser, or a backlight unit light diffuser film. The optical member composition of claim 1, further comprising 0.1 to 30 parts by weight of the light diffusing agent based on 100 parts by weight of the crystalline resin. The composition of claim 6, wherein the light diffusing agent has an average particle diameter of 0.1 to 50 μm. The method according to claim 1, wherein the ultraviolet absorber, the antistatic agent, the light stabilizer, the blowing agent, the plasticizer, the antioxidant, the heat stabilizer, the lubricant, the flame retardant, the filler, the mold release agent, the dye, the pigment, the antimicrobial agent, the anti-drip agent, and the nucleating agent. The composition for an optical member further comprising at least an additive. A backlight unit optical member of a display element comprising a resin substrate containing a crystalline resin having a crystallization temperature of 80 ° C. or higher as a base resin. The optical member of claim 9, wherein the crystalline resin comprises one resin, two or more copolymers, or a mixture selected from the group consisting of polyethylene resin, polypropylene resin, and polyester resin. The optical member of claim 9, wherein the crystalline resin has a weight average molecular weight of 1000 to 100000. The optical member of claim 9, wherein the crystalline resin exhibits a melting temperature of 100 ° C. or higher. 10. The optical member according to claim 9, which is made of a backlight unit reflector, a backlight unit light diffuser, or a backlight unit light diffuser film. The optical member of claim 9, wherein the resin substrate has a thickness of 100 to 15000 μm. 10. The optical member according to claim 9, further comprising a light diffusing agent dispersed in the resin substrate. The optical member of claim 15, wherein the light diffusing agent has an average particle diameter of 0.1 to 50 μm. 10. The optical member according to claim 9, wherein an embossing pattern of a predetermined shape is formed on at least one surface of the resin substrate. 18. The optical member of claim 17, wherein the embossed pattern is an amorphous pattern having an average roughness of 0.1 to 10 m. A backlight unit of a display device comprising the optical member of claim 9. A display device comprising the backlight unit of claim 19.