KR101372295B1 - Light diffusing polystyrene resin composition and monolayer light diffusing sheet containing the same - Google Patents

Abstract

The present invention relates to providing a light diffusing plate having a single layer structure from a light diffusing polystyrene resin composition comprising a polystyrene resin, a light diffusing agent, a fluorescent brightener and an ultraviolet absorber.
The light diffusing plate having a single layer structure manufactured in the present invention reduces the cost of raw materials due to the use of conventional expensive resins, and reduces the production cost according to the simplification of the manufacturing process, and thus has excellent optical properties, and thus covers a lighting fixture protection cover or signage. In addition, it can be applied to direct type BLU such as LCD or LED TV.

Description

Light diffusing polystyrene resin composition and monolayer light diffusing sheet containing the same}

The present invention relates to a light diffusing polystyrene resin composition and a light diffusion plate having a monolayer structure including the same, and more particularly to a light diffusing polystyrene resin including a polystyrene resin, a light diffusing agent, a fluorescent brightener and an ultraviolet absorber. It is to provide a light diffusing plate having a single layer structure from the composition.

Light diffusion plates are used for optical applications such as signage plates, lighting fixtures, protective covers for automobile direction indicators, diffuser plates and display panels applied to direct-type backlight units (BLUs) for displays. In general, the light diffusion plate has a sheet shape that makes a point or line light source appear as a uniform surface light source, and excellent light transmittance and light diffusivity are required in order to realize uniform brightness without the back light or contents being visible from the outside. .

In addition, there is a difference in the mechanical and optical properties required according to the specific use of the light diffusion plate. When directly exposed to the outside, such as a signboard, there is no deformation or discoloration due to impact strength, sunlight, temperature, humidity, etc. Should be met. On the other hand, in the case of indoor lighting fixtures should be excellent in moldability to create a variety of shapes from the design and aesthetic point of view rather than impact resistance, weather resistance. In addition, the light diffusion plate applied to the direct-type BLU for display such as liquid crystal display (LCD) or light emitting diode (LED) TV has good light transmittance and light transmittance while preventing deterioration due to light, and shielding the light source of the BLU. Basically, the optical properties must be excellent in both the diffusivity, and in addition, the hygroscopicity of the thermoplastic resin which is the main plate of the optical diffuser is low, so that the warpage of the light diffuser must not be deformed and the heat resistance is high. It must be able to cope with the deformation. Such a light diffusing plate is usually molded in a sheet form by mixing additives such as a light diffusing agent with a thermoplastic resin such as acrylic, polycarbonate, or polystyrene.

The inventors of the present patent application have already developed a multi-diffusion light diffuser plate having a thinner thickness and a higher luminance ratio than a conventional light diffuser plate based on polystyrene resin or methyl methacrylate-styrene copolymer resin and registered as a patent. There is a bar. However, this multi-layered light diffusion plate contains polymethyl methacrylate (PMMA) beads and other additives in the methyl methacrylate-styrene copolymer resin (MS), which is a skin layer, to improve warpage and heat resistance in LCD TV BLU. Although it was possible to achieve the effect, in order to realize a multilayered structure, resins of different components must be used in each layer, and a lamination process of an upper layer and a lower layer must be accompanied on a base layer or a core layer. One).

On the other hand, as a prior art related to a light diffusion plate using polystyrene resin as a main material, a light diffusion plate in which impact resistance and cracking are enhanced by adding an acrylic light diffusing agent having excellent adhesion and compatibility with a polystyrene resin as a light diffusing agent (Patent Document 2). ), A light diffusing plate (patent document 3) in which light diffusing property, light transmittance, and hiding property are balanced by adding a light diffusing agent having a different particle size to each resin layer separately to the laminated resin layer. Various techniques such as a light diffusion plate (Patent Document 4) which simultaneously impart light diffusivity and antistatic property by co-extrusion molding a resin layer in which a ground layer and an antistatic agent are dispersed and integrated are known, but most of them are other than polystyrene resins. The present invention relates to a light diffusing plate having a multilayer structure using a methyl methacrylate-styrene copolymer resin or the like (see FIG. 1). That there is a problem such as increase in manufacturing cost due to the introduction of the lamination process, such as co-extrusion molding to have a charge and a multi-layer structure of the raw material costs of the use.

Patent Documents 1. Korean Registered Patent Publication No. 10-1170776 Patent Document 2. Korea Patent Publication No. 10-1035872 Patent Document 3. Japanese Patent No. 3374316 Patent Document 4. Japanese Patent Application Laid-Open No. 11-5241

Therefore, the present invention has been devised in view of the above problems, and an object of the present invention is to reduce the cost of raw materials due to the use of conventional expensive resins, and to reduce the production cost according to the simplification of the manufacturing process, while the light diffusion of the multilayer structure. It is an object of the present invention to provide a light diffusing plate having a single layer structure from a light diffusing polystyrene resin composition comprising a polystyrene resin, a light diffusing agent, a fluorescent brightener, and an ultraviolet absorber, having optical properties equivalent to or higher than those of the plate.

The present invention for achieving the above object is a light-diffusion polystyrene resin containing 0.1 to 10 parts by weight of light diffusing agent, 0.01 to 0.05 parts by weight of fluorescent brightener and 0.05 to 0.2 parts by weight of ultraviolet absorber based on 100 parts by weight of polystyrene resin. To provide a composition.

In addition, the light-diffusion polystyrene resin composition is characterized in that it further comprises 0.05 to 0.2 parts by weight of the hindered amine light stabilizer.

In addition, the light diffusing agent is calcium carbonate particles, barium sulfate particles, titanium oxide particles, aluminum hydroxide particles, silica particles, glass particles, mica particles, magnesium oxide particles, zinc oxide particles, acrylic crosslinked particles, silicon-based crosslinked particles, styrene-based It is characterized by any one selected from the group consisting of crosslinked particles and mixtures thereof.

In addition, the light diffusing agent particles are characterized in that the average particle diameter of 1 ~ 10 μm.

In addition, the fluorescent brightener is characterized in any one selected from the group consisting of triazine-based, benzoxazole-based, coumarin-based, imidazole-based, pyrazoline-based, stilbene-based compounds and mixtures thereof.

In addition, the ultraviolet absorber, benzophenone, benzotriazole, salicylate, benzoate, nickel complex salt, oxalanilide, cyanoacrylate, malonic ester, cinnamic acid ester and mixtures thereof It is characterized in that any one selected from the group consisting of.

In addition, the light-diffusion polystyrene resin composition is characterized in that it further comprises any one or two or more additives selected from the group consisting of antioxidants, antistatic agents, flame retardants, lubricants and pigments.

The present invention also provides a light diffusion plate having a single layer structure including the light diffusing polystyrene resin composition.

According to the present invention, a light diffusing plate having a single layer structure made from a light diffusing polystyrene resin composition comprising a polystyrene resin, a light diffusing agent, a fluorescent brightener, and an ultraviolet light absorbing agent has a cost of raw materials due to the use of conventional expensive resins. It reduces the cost of production by simplifying the manufacturing process and shows the same or more optical properties compared to the light diffusing plate of the multi-layer structure, so it can be applied not only to the lighting protection cover or signboard but also to the direct type BLU such as LCD or LED TV. Application is possible.

1 is an exploded view of a light diffusion plate having a conventional multilayer structure.
Figure 2 is a single layer light diffuser plate embossed formed on the surface according to the present invention.

Hereinafter, a light diffusing polystyrene resin composition comprising a polystyrene resin, a light diffusing agent, a fluorescent brightener, and an ultraviolet absorber according to the present invention, and a light diffusing plate having a single layer structure will be described in detail.

The present invention provides a light-diffusion polystyrene resin composition comprising 0.1 to 10 parts by weight of a light diffusing agent, 0.01 to 0.05 parts by weight of a fluorescent brightener and 0.05 to 0.2 parts by weight of an ultraviolet absorber based on 100 parts by weight of polystyrene resin.

First, as a polystyrene resin, a general purpose polystyrene (GPPS) resin suitable for optics and inexpensive is used alone, but an impact polystyrene resin which can improve impact strength may be appropriately blended.

The present invention is to improve the light transmittance and light diffusing property by mixing the light diffusing agent in the polystyrene resin, the light diffusing agent is used in the inorganic or organic transparent particles different in refractive index from the polystyrene resin which is the main material of the light diffusion plate Examples of the inorganic particles include calcium carbonate particles, barium sulfate particles, titanium oxide particles, aluminum hydroxide particles, silica particles, glass particles, mica particles, magnesium oxide particles, and zinc oxide particles. Particles, silicone-based crosslinked particles or styrene-based crosslinked particles may be used, and the organic particles and inorganic particles may be used alone or in combination of two or more. Organic acrylic crosslinked particles, silicone crosslinked particles or styrene crosslinked particles having excellent light resistance are preferably used.

The light diffusing agent is mixed with 0.1 to 10 parts by weight based on 100 parts by weight of polystyrene resin, the light diffusion effect is insignificant if the content of the light diffusing agent is less than 0.1 parts by weight, the light diffusion effect is improved if it exceeds 10 parts by weight On the other hand, since the brightness is lowered, it is preferable to adjust the light diffusing agent within the above range.

In addition, the light diffusing agent is mixed in the form of particles in consideration of compatibility and dispersibility with the polystyrene resin, the average particle diameter of the light diffusing agent particles is preferably 1 ~ 10 μm. If the average particle diameter of the light diffusing agent particles is less than 1 μm, yellowing of the light diffusing plate may occur. It is difficult to expect a diffusion effect.

In addition, the fluorescent brightener generally absorbs ultraviolet light in the wavelength range of 360 to 380 nm to re-radiate blue-violet visible light having a longer wavelength, and has a function of giving gloss to the light diffusion plate.

As the optical brightener, any one selected from the group consisting of triazine-based, benzoxazole-based, coumarin-based, imidazole-based, pyrazoline-based, stilbene-based compounds, and mixtures thereof is used, and 2,2 'is used as the benzoxazole-based compound. -(1,2-ethenediyldi-4,1-phenylene) bisbenzoxazole can be used more preferably. Such a fluorescent brightener preferably contains 0.01 to 0.05 parts by weight with respect to 100 parts by weight of polystyrene resin.

On the other hand, ultraviolet light emitted from sunlight or other light sources, that is, light having a wavelength of 280 to 400 nm, causes a yellowing phenomenon by deteriorating a thermoplastic resin such as a polystyrene resin, and thus an optical diffuser manufactured from such a thermoplastic resin has optical and mechanical properties. Will fall. Therefore, the optical polystyrene resin composition according to the present invention contains an ultraviolet absorber, and can impart light resistance to the light diffusing plate and sufficiently suppress coloring caused by visible light absorption of the ultraviolet absorber.

As the ultraviolet absorber, a group consisting of benzophenone series, benzotriazole series, salicylate series, benzoate series, nickel complex salt series, oxalanilide series, cyanoacrylate series, malonic ester series, cinnamic acid ester series and mixtures thereof Any one selected from may be used, and 2- (2'-hydroxy-5-methylphenyl) benzotriazole may be more preferably used as the benzotriazole-based compound. It is preferable that such a ultraviolet absorber contains 0.05-0.2 weight part with respect to 100 weight part of polystyrene resins.

In addition, the optical acid polystyrene resin composition of the present invention may further include 0.05 to 0.2 parts by weight of a hindered amine light stabilizer (hals) in order to further improve the light resistance by ultraviolet rays, hindered amine As the light stabilizer, any of 2,2,6,6-tetraalkyl piperidine derivatives can be used without limitation, and bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate can be used. More preferably. It is preferable that such a hindered amine light stabilizer contains 0.05-0.2 weight part with respect to 100 weight part of polystyrene resins.

In addition, the light-diffusion polystyrene resin composition of the present invention may further include any one or two or more additives selected from the group consisting of antioxidants, antistatic agents, flame retardants, lubricants and pigments according to the requirements.

The present invention also provides a light diffusion plate having a single layer structure including the light diffusing polystyrene resin composition. As shown in FIG. 2, the light diffusing plate having a single layer structure manufactured from the light diffusing polystyrene resin composition of the present invention has embossing on its surface. The embossing pattern uniformly scatters the light incident from the lamp, and serves to make the bright lines of the lamp invisible. That is, light directly incident from the lamp is scattered and diffused in various directions instead of a constant direction through an embossing pattern, thereby increasing light transmittance and light diffusivity and increasing overall luminance. The size of the embossing pattern is adjustable according to the distance between the light diffusing plate and the lamp, the brightness of the lamp, the number of lamps, the arrangement of the lamps, and the like. Do.

Therefore, the single-layer light diffusing plate manufactured from the light diffusing polystyrene resin composition of the present invention is a raw material cost by using an expensive resin such as methyl methacrylate-styrene copolymer resin in addition to the polystyrene resin as the main resin of the conventional light diffusing plate. It reduces the burden and reduces the production cost by simplifying the manufacturing process by eliminating the pneumatic shaping process to form the laminated structure, while showing the same or more optical properties compared to the light diffusing plate of the multilayer structure to protect the lighting fixture. It can be applied to direct type BLU such as LCD or LED TV as well as cover or sign.

Hereinafter, specific embodiments will be described in detail.

( Example  One)

50kg of silicone-based crosslinked particles having an average particle diameter of 2? As a light diffusing agent in 1,000kg of a polystyrene resin of general purpose, and 2,2 '-(1,2-ethenedylyl-4,1-phenylene) bisbenzazole as a fluorescent brightener 0.2 kg and 1 kg of 2- (2'-hydroxy-5-methylphenyl) benzotriazole were added as a UV absorber and mixed with a high speed stirrer, and then pellet material was obtained using an extruder. After drying the pellets of the raw resin, a 1.5 mm thick single layer light diffuser plate having an embossing of 11 μm was formed on the surface using a sheet extruder.

( Example  2)

100 kg of acrylic crosslinked particles having an average particle diameter of 1 μm were used as the light diffusing agent, and 1 kg of bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate was added as a hindered amine light stabilizer. A single layer light diffuser plate having a thickness of 1.5 mm was prepared in the same manner as in Example 1, except that it was used.

( Comparative Example  One)

0.5 kg of silicone-based crosslinked particles having an average particle diameter of 0.3 μm as a light diffusing agent in 1,000 kg of a general-purpose polystyrene resin, and 2,2 '-(1,2-ethenedylyl-4,1-phenylene) bisbenzoxa as a fluorescent brightener 0.05 kg of sol and 0.2 kg of 2- (2'-hydroxy-5-methylphenyl) benzotriazole were added as a UV absorber and mixed with a high speed stirrer, and then pellet material was obtained using an extruder. After drying the pellets of the raw material resin, a 1.5 mm thick single layer light diffuser plate having an embossing of 5 μm was formed on the surface using a sheet extruder.

( Comparative Example  2)

A light diffusion plate having a multilayer structure of 1.5 mm thickness, which is the same as that disclosed in Korean Patent Application Publication No. 10-1170776 (Patent Document 1), which is a prior patent of the present patent applicant, was prepared.

( Test Example )

The optical properties of the light diffusion plates prepared in Examples 1 and 2 and Comparative Examples 1 and 2 were measured by the following method.

(1) Total light transmittance and light haze were measured using a haze meter according to the ASTM D1003 method.

(2) the light diffusivity is byeongak number using a photometer wide angle 0 ° of the light transmittance I _0, I ₇₀ can light transmission of the wide-angle 70 °, and the measurement was calculated from the equation below.

Light diffusivity (%) = (I ₇₀ / I ₀ ) X 100

(3) Surface glossiness measured the mirror glossiness of 60 ° according to the JIS K7105 method with a glossmeter.

(4) Light resistance was measured after irradiating ultraviolet rays at 60 ° C. for 72 hours using ATLAS-UVCON, and then measured YI (Yellow Index) variation.

(5) Luminance was calculated as the brightness of the light emitted per unit area (cd / m ² ) using a luminance meter.

division Total light transmittance
(%) Light diffusivity (haze)
(%) Light diffusivity
(%) Surface gloss
(%) △ YI Luminance
(cd / m ² ) Example 1 62.7 98.6 30.2 42.0 1.2 8,727 Example 2 62.5 98.4 30.1 40.3 1.0 8,650 Comparative Example 1 52.2 98.0 21.3 34.2 2.1 8,050 Comparative Example 2 62.6 98.6 30.1 40.5 1.2 8,594

As shown in Table 1, the single-layer light diffusing plates of Examples 1 and 2 prepared according to the present invention have a total light transmittance, a haze, a light diffusing rate, It can be seen that the optical properties such as surface glossiness, light resistance and luminance are all excellent. In addition, Example 2 further comprising a hindered amine light stabilizer was confirmed that the light resistance further improved compared to Example 1.

In addition, it was confirmed that the single-layer light diffusing plates of Examples 1 and 2 prepared according to the present invention had the same or more optical properties than the light diffusing plates of the conventional multilayer structure prepared from Comparative Example 2. Therefore, the single-layer light diffusion plate according to the present invention can not only mass-produce light diffusion products such as protective covers or signs for lighting fixtures by secondary processing such as vacuum molding at low cost, but also apply to direct type BLU for large TVs. You can expect it to be possible.

110. Interlayer (polystyrene resin)
120. Lower layer (methyl methacrylate-styrene copolymer resin or polystyrene resin)
130. Upper layer (methyl methacrylate-styrene copolymer resin or polystyrene resin)
121, 131. Embossing

Claims (8)

As a light diffusion plate comprising a light-diffusion polystyrene resin composition comprising 0.1 to 10 parts by weight of a light diffusing agent, 0.01 to 0.05 parts by weight of a fluorescent brightener and 0.05 to 0.2 parts by weight of an ultraviolet absorber with respect to 100 parts by weight of polystyrene resin,
The light diffusing agent is calcium carbonate particles, barium sulfate particles, titanium oxide particles, aluminum hydroxide particles, silica particles, glass particles, mica particles, magnesium oxide particles, zinc oxide particles, acrylic crosslinked particles having an average particle diameter of 1 ~ 10 μm, Any one selected from the group consisting of silicone-based crosslinked particles, styrene-based crosslinked particles, and mixtures thereof, and the fluorescent brightener is 2,2 '-(1,2-ethenedylyl-4,1-phenylene) bisbenz Oxazole, the ultraviolet absorber is 2- (2'-hydroxy-5-methylphenyl) benzotriazole, and the light diffusing plate is a light diffusing layer having a single layer structure having an embossing having a size of 11-19 μm on its surface. plate. delete delete delete delete The light diffusing plate according to claim 1, further comprising 0.05 to 0.2 parts by weight of the hindered amine light stabilizer. The light diffusing plate according to claim 1, further comprising any one or two or more additives selected from the group consisting of an antioxidant, an antistatic agent, a flame retardant, a lubricant, and a pigment. delete

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