JP2010229193A - Light-diffusing polycarbonate resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-diffusing resin composition useful as a material of a member composed of a light-diffusing molded article, for example, a cover or a lens for various displays where an LED is used, a lens cover, an illumination cover, a lighting signboard, a transmission screen, various displays, a light-diffusing sheet of a liquid crystal display device, a light guide plate, and the like. <P>SOLUTION: The light-diffusing polycarbonate resin composition contains a polycarbonate resin (A) and polymer fine particles (B) having a refractive index different from that of the polycarbonate resin by 0.01-0.08 and having an average particle size of 5-20 μm, where the polymer fine particles are contained in the polycarbonate resin so that the compounding factor, represented by the product of an average particle size (μm) and the content (mass%) of the polymer fine particle, is 6.2-11.8. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention is a member made of a light diffusing molded article, for example, a lighting fixture using LEDs, various display covers and lenses, lens covers, lighting covers such as other lighting fixtures, lighting signs, transmissive screens, The present invention relates to a light diffusing polycarbonate resin composition useful as a material for various displays, light diffusing sheets for liquid crystal display devices, light guide plates and the like. More specifically, it is made of polycarbonate and resin fine particles having a specific refractive index, specifically acrylic-styrene copolymer fine particles, and has high total light transmittance and high haze. In particular, various display covers using LEDs and When used as a lens, the present invention relates to a light diffusing polycarbonate resin composition that can constitute a diffusion plate capable of displaying LED without glare.

Polycarbonate has a wide range of uses as a thermoplastic resin with excellent impact resistance, heat resistance, and transparency, and is lighter and more productive than inorganic glass. It can also be suitably used for applications requiring light diffusibility, such as transmission screens, various displays, light diffusion sheets for liquid crystal display devices, and light guide plates.
Further, in order to impart light diffusibility to the polycarbonate, addition of inorganic compounds such as glass, silica, aluminum hydroxide, etc. has been proposed. The heat stability at the time of extrusion was low, and there was a drawback that the mechanical strength such as impact strength was greatly reduced.

As a light diffusing polycarbonate resin improved in such a defect, for example, Patent Document 1 discloses that a polycarbonate resin is made of a material having a refractive index having a large refractive index difference compared to the refractive index of the polycarbonate resin. A light diffusing polycarbonate resin in which a small amount of fine particles, specifically, polymethyl methacrylate fine particles are added in a relatively small amount, is disclosed. As described in the examples, the total light transmittance is as low as less than 80%. It was inferior in practicality.

Patent Document 2 discloses an aromatic polycarbonate resin 1 as a molding material suitable for a light diffusing plate.
A light diffusing resin composition obtained by adding a small amount of a bead-shaped cross-linked acrylic resin having a large refractive index difference compared to polycarbonate, specifically, 0.01 to 1 part by weight (part by weight) to 00 parts by weight (part by weight). However, the performance of eliminating glare when using an LED light source was insufficient.
In Patent Document 3, as a resin composition having excellent light transmittance and light diffusibility, 0.1 to 5 parts by weight (parts by mass) of calcium carbonate (B) per 100 parts by weight (parts by mass) of the polycarbonate resin (A). ), 0.01 to 0.3 parts by weight (parts by mass) of titanium oxide (C) and 0.0001 to 2 parts by weight (parts by weight) of polyorganohydrogensiloxane (D). Although disclosed, it is not satisfactory in terms of thermal stability and impact resistance, and the total light transmittance is also insufficient.
In addition, the molded product of Patent Documents 1 to 3 and the molded product made of the resin composition are not described when a light source having a low luminous flux and a high directivity is used as the light source. Even when used for various purposes, it is difficult to eliminate the glare of the LED, and therefore, display with excellent visibility is impossible.

Conventionally, light diffusing polycarbonate resin compositions have been used in lighting fixtures that use a space between cathodes. However, a bead-shaped crosslinked acrylic resin having a large refractive index difference compared to polycarbonate is used to achieve a target haze. When the amount added was adjusted, the yield during production was low, and improvement of the composition was demanded to improve productivity.
The reason why the yield was low is that the diffusion particles used had a small average particle size and a large refractive index difference with respect to the polycarbonate resin, so that the amount of fine particles added was small, but the product lot of particle size As a result, a slight fluctuation at each time has a great influence on the target optical characteristics (diffusibility varies from product lot to product lot), resulting in a situation where many off-spec products are produced.
In addition, if the amount of fine particles added is small, in order to make up for the disadvantage that the inside of the thin molded product can be seen through, it was possible to increase the amount of fine particles added. There was also.

Japanese Patent Laid-Open No. 03-143950 Japanese Patent Laid-Open No. 10-046018 JP 2000-169695 A

  An object of the present invention is to obtain a light diffusing polycarbonate resin composition that is effective for LED, particularly white LED luminaires, rather than the conventional use of inter-cathode luminaires.

  Since the light source of LED (light emitting diode) is smaller than that between the cathodes, the inventors have found that the particle size of the diffusing agent needs to be larger and the addition amount needs to be larger than before. did.

By selecting a diffusing agent having a large particle diameter, the surface area per unit volume of the particle is reduced, so that it was necessary to increase the amount of addition in order to maintain the same diffusion efficiency as before.
In addition, since a diffusing agent having a small difference in refractive index from the polycarbonate resin was selected, the entrance angle of refraction into the particles was reduced, and it was necessary to increase the amount of addition in order to maintain the same diffusion efficiency as before.

  However, the increased amount of diffusing agent with a large particle size means that even if there is a fluctuation in the particle size of each product lot of the diffusing agent, the ratio of the fluctuation width to the particle size becomes smaller than before. This means that, by using a diffusing agent with a smaller refractive index difference, as a result, while maintaining the diffusion efficiency at the same level as the conventional one, it has been found that the brightness is improved compared to the conventional one. Can be produced stably.

  As described above, the present invention is based on the concept that is completely opposite to the conventional idea of adding a small amount of fine particles having a large refractive index difference to the polycarbonate resin that is a base resin. It is made by adding a relatively large amount of particles having a relatively large particle shape to the resin, which is made of a material having a small difference in refractive index.

That is, the gist of the present invention is as follows.
A polymer fine particle (B) having a refractive index difference of 0.01 to 0.08 and an average particle size of 5 to 20 μm is contained between the polycarbonate resin (A) and the polycarbonate resin. A light-diffusing polycarbonate resin composition containing a blending coefficient represented by a product of an average particle size (μm) and a content (% by mass) of polymer fine particles of 6.2 to 11.8. .

  The light diffusing polycarbonate resin composition of the present invention eliminates the glare of the LED and has a high total light transmittance and brightness, so that the lens or lens cover of the signal lamp using the LED, the illumination cover, Can be widely used in applications requiring light diffusivity such as lighting signs, transmissive screens, various displays, light diffusing sheets for liquid crystal display devices, light guide plates, etc., especially for display devices using LEDs as light sources Very good.

Hereinafter, the present invention will be described in detail.
<(A) Polycarbonate resin>
The polycarbonate resin used in the present invention is obtained by an interfacial polymerization method of an aromatic dihydroxy compound or a small amount thereof and phosgene, or an aromatic dihydroxy compound or a small amount of this compound and a carbonic acid. An aromatic polycarbonate polymer which may be branched, which is produced by a transesterification reaction with a diester.

  Examples of the aromatic dihydroxy compound include 2,2-bis (4-hydroxyphenyl) propane (= bisphenol A), 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane (= tetramethylbisphenol A). Bis (4-hydroxyphenyl) alkane-based dihydroxy compounds such as 2,2-bis (4-hydroxy-3,5-dibromophenyl) propane (= tetrabromobisphenol A), 2,2-bis (4-hydroxy) -1,3-bis (4-hydroxyphenyl) cyclohexane, hydroquinone, resorcinol in addition to bis (4-hydroxyphenyl) alkane dihydroxy compounds containing halogen such as −3,5-dichlorophenyl) propane (= tetrachlorobisphenol A) 4,4-dihydroxydiphenyl The like, preferably contain a halogen also include good bis (4-hydroxyphenyl) alkane-based dihydroxy compounds, particularly preferred include bisphenol A. These aromatic dihydroxy compounds may be used alone or in combination.

  In order to obtain a branched polycarbonate, phloroglucin, 4,6-dimethyl-2,4,6-tri (4-hydroxyphenyl) heptene-2, 4,6-dimethyl-2,4,6-tri (4 -Hydroxyphenyl) heptane, 2,6-dimethyl-2,4,6-tri (4-hydroxyphenylheptene-3,1,3,5-tri (4-hydroxyphenyl) benzene, 1,1,1- Polyhydroxy compounds represented by tri (4-hydroxyphenyl) ethane and the like, and 3,3-bis (4-hydroxyaryl) oxindole (= isatin bisphenol), 5-chlorisatin bisphenol, and 5,7-dichlorois Trihydroxy or higher polyhydroxy compounds such as chin bisphenol and 5-bromoisatin bisphenol The amount of polyhydroxy compound used is, for example, about 0.1 to 2 mol% of the dihydroxy compound.

  Furthermore, a monovalent aromatic hydroxy compound or the like can be used as a molecular weight regulator. Examples of the molecular weight modifier include m- and p-methylphenol, m- and p-propylphenol, p-bromophenol, p-tert-butylphenol, and p-long chain alkyl-substituted phenol.

The molecular weight of the polycarbonate resin used in the present invention is a viscosity average molecular weight measured from the viscosity of the methylene chloride solution at 25 ° C., preferably 16,000 to 38,000, more preferably 18,000 to 35,000. .
The polycarbonate resin used in the present invention may be a mixture of two or more.
The refractive index of polycarbonate is preferably adjusted to 1.57 to 1.60.

<(B) Acrylic-styrene copolymer fine particles>
The polymer fine particles used as the light diffusing agent in the present invention may be any fine particles having a predetermined refractive index and particle size, and specific examples include acrylic-styrene copolymer fine particles. Acrylic-styrene copolymer fine particles are fine particles obtained by copolymerizing an acrylic monomer and a styrene monomer, for example, fine particles obtained by polymerizing an acrylic monomer and a styrene monomer by a suspension polymerization method or the like. It is preferable that it is crosslinked using a crosslinking agent. As acrylic monomers, for example, methacrylate monomers such as methyl methacrylate and ethyl methacrylate, acrylate monomers such as methyl acrylate and ethyl acrylate, acrylamide, and the like can be exemplified as typical examples. Examples of styrene monomers include styrene and α-methyl. Styrene, vinyltoluene and the like can be exemplified as typical examples. In the copolymerization of these monomers, these monomers may be used as the main components, and other monomers may be copolymerized as necessary. Examples of the crosslinking agent include commonly used ones such as ethylene glycol dimethacrylate, divinylbenzene, 1,6-hexanediol, trimethylpropane trimethacrylate, trimethylpropane trimethacrylate, and trimethylpropane triacrylate. Functional monomers can be used.

The weight average particle diameter of the acrylic-styrene copolymer fine particles used in the present invention is 5 to 20 μm, preferably 10 to 15 μm. If the particle diameter is less than 5 μm, the amount of fine particles added is small, so that the variation in target haze increases, and if it exceeds 20 μm, the amount of fine particles added is large and the strength of the molded member decreases.
The particle size distribution of the fine particles is desirably 5% by mass or less for particles having a particle size of 5 μm or less, and 10% by mass or less for particles having a particle size exceeding 20 μm.

The acrylic-styrene copolymer fine particles preferably have a refractive index difference of 0.01 to 0.08 with respect to the polycarbonate resin composition. The refractive index of the acrylic-styrene copolymer fine particles can be adjusted by changing the copolymerization ratio of the acrylic monomer and the styrene monomer in the range of 99: 1 to 1:99. However, if the copolymerization ratio of the styrenic monomer is too high, the light resistance is reduced and yellowish, and conversely if the copolymerization ratio of the acrylic monomer is too high, the refractive index between the fine particles and the polycarbonate The difference between the two is too wide, the glare of the LED light source is conspicuous, and the visibility is low. In the present invention, the acrylic-styrene copolymer fine particles have a refractive index of 1.52 to 1.57, preferably 1.53 to 1.56, more preferably 1.54 to 1.56. To do.
In order to obtain fine particles having such a refractive index, it is necessary to adjust the copolymerization ratio of the acrylic monomer and the styrene monomer. Although the adjustment ratio varies depending on the monomer used, the refractive index becomes lower when a large amount of acrylic monomer is used, and the refractive index becomes higher when a large amount of styrene monomer is used. For example, when methyl methacrylate is used as an acrylic monomer and styrene is used as a styrene monomer, the ratio of acrylic monomer to styrene monomer is about 7: 3 when the refractive index is adjusted to about 1.52. When the ratio is adjusted to about 1.56, it is about 3: 7, and usually it should be adjusted before and after this.

The structure of the acrylic-styrene copolymer fine particles used in the present invention is not particularly limited, but the hollow one is easily deformed when mixed with a polycarbonate resin or when molding a resin composition, and the appearance of the molded product is This is not preferable because it often becomes defective and the balance between light diffusibility and light transmittance is often not so good. A porous material is excellent in light diffusibility even in a small amount, but is not preferred because the transmittance tends to decrease. In the case of fine particles having a two-layer structure of a core part and a shell part, the shell part is an acrylic-styrene copolymer fine particle, and the particle diameter and refractive index satisfy the scope of the present invention. Can be used. In that case, a core having a refractive index lower than that of the shell portion such as polymethyl methacrylate or silicone is preferable. However, in the case of such multi-layer structured fine particles, the cost may increase, and in the present invention, solid fine particles of an acrylic-styrene cross-linked copolymer are preferable.
As the acrylic-styrene copolymer fine particles usable in the present invention, those available from the market may be used. Examples of such commercially available products are, for example, from the GBS series or GSM series marketed by Gantz Kasei Co., Ltd. under the trade name Gantzpearl or Staphyloid, and conform to the physical properties defined in the present invention. To do.

The light diffusing polycarbonate resin composition of the present invention comprises polymer fine particles (B) having a refractive index difference of 0.01 to 0.08 and an average particle diameter of 5 to 20 μm between the polycarbonate resin (A) and the polycarbonate resin. The polymer fine particles are contained in the polycarbonate resin so that the blending coefficient represented by the product of the average particle diameter (μm) and the content (% by mass) of the polymer fine particles is 6.2 to 11.8. A light diffusing polycarbonate resin composition.
The compounding coefficient means that a large number of particles having a large particle diameter are added. By making it within a specific range, the yield of the light diffusing polycarbonate resin composition, which is the target optical characteristic, is improved, and the strength of the molded member is maintained. Is possible.
When the blending coefficient is smaller than 6.2, the diffusibility is insufficient and the light source can be seen through, or even if the target haze is obtained, the production yield is low, and industrially stable production cannot be achieved. When the blending coefficient is larger than 11.8, the diffusibility is too high and the lightness is insufficient or the strength of the molded member is lowered.

<(C) Other additives>
In the light diffusing resin composition of the present invention, for example, an ultraviolet absorber, an antioxidant, a fluorescent brightener, a release agent, an antistatic agent, a colorant, a heat stabilizer, a fluidity improver, if necessary. You may add a flame retardant, an aggregation inhibitor, etc.

<(C-1) UV absorber>
Examples of the ultraviolet absorber used in the present invention include inorganic ultraviolet absorbers such as cerium oxide and zinc oxide; benzotriazole compounds, benzophenone compounds, salicylate compounds, cyanoacrylate compounds, triazine compounds, oxanilide compounds, malonic ester compounds, hindered amines. Examples include organic ultraviolet absorbers such as compounds. In these, an organic ultraviolet absorber is preferable and a benzotriazole compound is especially preferable.

  Specific examples of the benzotriazole compound include 2- (2′-hydroxy-5′-methylphenyl) benzotriazole and 2- [2′-hydroxy-3 ′, 5′-bis (α, α-dimethylbenzyl) phenyl. ] -Benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert-butyl-phenyl) -benzotriazole, 2- (2'-hydroxy-3'-tert-butyl-5'-methyl) Phenyl) -5-chlorobenzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-tert-butyl-phenyl) -5-chlorobenzotriazole), 2- (2′-hydroxy-3 ′, 5'-di-tert-amyl) -benzotriazole, 2- (2'-hydroxy-5'-tert-octylphenyl) benzotriazole, 2,2 ' -Methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2N-benzotriazol-2-yl) phenol] and the like. Among them, 2- (2′-hydroxy-5′-tert-octylphenyl) benzotriazole, 2,2′-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2N-benzotriazole) 2-yl) phenol] is preferred, and 2- (2′-hydroxy-5′-tert-octylphenyl) benzotriazole is particularly preferred. Among them, 2,2′-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2N-benzotriazol-2-yl) phenol] has low volatility during molding, This is preferable since there is little mold contamination.

  The content of the ultraviolet absorber is preferably 0.01 to 2 parts by mass, more preferably 0.05 to 1.5 parts by mass, with respect to 100 parts by mass of the polycarbonate resin. More preferably, it is 1 part by mass. If it is less than 0.01 part by mass, the effect is insufficient, and if it is more than 2 parts by mass, there is a problem of mold contamination during molding.

<(C-2) Thermal stabilizer, antioxidant>
As the heat stabilizer and the antioxidant, any conventionally known one can be used. Among them, a phosphorus compound is preferable as the heat stabilizer, and a phenol compound is preferable as the antioxidant, and these may be used in combination. Phosphorus compounds are generally effective in improving the residence stability at high temperatures and heat stability when using resin moldings when melt-kneading polycarbonate resins, and phenol compounds are generally effective in heat aging resistance, etc. The heat resistance stability when using the polycarbonate resin molded body is high. Further, by using a phosphorus compound and a phenol compound in combination, the effect of improving the colorability is further improved.

<(C-2-1) Phosphorus Heat Stabilizer>
Examples of the phosphorus-based heat stabilizer used in the present invention include phosphorous acid, phosphoric acid, phosphite ester, phosphate ester, etc. Among them, trivalent phosphorus is included, and it is easy to express a discoloration suppressing effect. Phosphites such as phosphites and phosphonites are preferred.

  Specific examples of the phosphite include triphenyl phosphite, tris (nonylphenyl) phosphite, dilauryl hydrogen phosphite, triethyl phosphite, tridecyl phosphite, tris (2-ethylhexyl) phosphite, and tris. (Tridecyl) phosphite, tristearyl phosphite, diphenyl monodecyl phosphite, monophenyl didecyl phosphite, diphenyl mono (tridecyl) phosphite, tetraphenyl dipropylene glycol diphosphite, tetraphenyl tetra (tridecyl) pentaerythritol tetra Phosphite, hydrogenated bisphenol A phenol phosphite polymer, diphenyl hydrogen phosphite, 4,4′-butylidene-bis (3-methyl-6-t rt-butylphenyldi (tridecyl) phosphite) tetra (tridecyl) 4,4'-isopropylidenediphenyldiphosphite, bis (tridecyl) pentaerythritol diphosphite, bis (nonylphenyl) pentaerythritol diphosphite, dilauryl Pentaerythritol diphosphite, distearyl pentaerythritol diphosphite, tris (4-tert-butylphenyl) phosphite, tris (2,4-di-tert-butylphenyl) phosphite, hydrogenated bisphenol A pentaerythritol phosphite Polymer, bis (2,4-di-tert-butylphenyl) pentaerythritol diphosphite, bis (2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphos Aito, 2,2'-methylenebis (4,6-di -tert- butylphenyl) octyl phosphite, bis (2,4-dicumylphenyl) pentaerythritol diphosphite and the like.

  Examples of phosphonites include tetrakis (2,4-di-iso-propylphenyl) -4,4′-biphenylenediphosphonite, tetrakis (2,4-di-n-butylphenyl) -4,4′-biphenyl. Range phosphonite, tetrakis (2,4-di-tert-butylphenyl) -4,4'-biphenylene diphosphonite, tetrakis (2,4-di-tert-butylphenyl) -4,3'-biphenylene diphospho Knight, tetrakis (2,4-di-tert-butylphenyl) -3,3'-biphenylenediphosphonite, tetrakis (2,6-di-iso-propylphenyl) -4,4'-biphenylenediphosphonite, Tetrakis (2,6-di-n-butylphenyl) -4,4′-biphenylenediphosphonite, tetrakis (2,6- -Tert-butylphenyl) -4,4'-biphenylenediphosphonite, tetrakis (2,6-di-tert-butylphenyl) -4,3'-biphenylenediphosphonite, and tetrakis (2,6-di-) tert-butylphenyl) -3,3′-biphenylenediphosphonite.

  Examples of the acid phosphate include methyl acid phosphate, ethyl acid phosphate, propyl acid phosphate, isopropyl acid phosphate, butyl acid phosphate, butoxyethyl acid phosphate, octyl acid phosphate, 2-ethylhexyl acid phosphate, decyl acid phosphate, and lauryl phosphate. Phosphate, stearyl acid phosphate, oleyl acid phosphate, behenyl acid phosphate, phenyl acid phosphate, nonyl phenyl acid phosphate, cyclohexyl acid phosphate, phenoxyethyl acid phosphate, alkoxy polyethylene glycol acid phosphate, bisphenol A acid Sulfate, dimethyl acid phosphate, diethyl acid phosphate, dipropyl acid phosphate, diisopropyl acid phosphate, dibutyl acid phosphate, dioctyl acid phosphate, di-2-ethylhexyl acid phosphate, dioctyl acid phosphate, dilauryl acid phosphate, distearyl acid phenyl Acid phosphate, bisnonylphenyl acid phosphate, etc. are mentioned.

  Among the phosphites, distearyl pentaerythritol diphosphite, tris (2,4-di-tert-butylphenyl) phosphite, bis (2,6-di-tert-butyl-4-methylphenyl) penta Erythritol diphosphite, 2,2′-methylenebis (4,6-di-tert-butylphenyl) octyl phosphite, bis (2,4-dicumylphenyl) pentaerythritol diphosphite are preferable, and heat resistance is good. Tris (2,4-di-tert-butylphenyl) phosphite is particularly preferred in that it is difficult to hydrolyze.

The content of the phosphorus-based heat stabilizer used in the present invention may be appropriately selected and determined, but is usually 0.0001 to 0.5 parts by mass with respect to 100 parts by mass of the polycarbonate resin (A). 0.001 to 0.3 parts by mass is preferable, and 0.01 to 0.1 parts by mass is particularly preferable. If the content of the heat stabilizer is too small, the effect is insufficient. Conversely, if the content is too large, the molecular weight of the polycarbonate resin may be lowered or the hue may be lowered.

<(C-2-2) phenolic antioxidant>
As the phenol-based antioxidant of the present invention, a phenol compound having a specific structure in the molecule is preferable. Specifically, for example, 2,2′-methylenebis (4-methyl-6-tert-butylphenol), 4,4′- Butylidenebis (6-tert-butyl-3-methylphenol), 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 3,9-bis [2- {3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy} -1,1-dimethylethyl] -2,4,8,10-tetraoxaspiro [5.5] undecane, triethylene glycol bis [Β- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionate], 1,6-hexanediol bis [β- ( -Tert-butyl-4-hydroxy-5-methylphenyl) propionate], pentaerythritol-tetrakis [β- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionate], octadecyl [β- (3- tert-butyl-4-hydroxy-5-methylphenyl) propionate] and the like.

  Among these, 4,4′-butylidenebis (6-tert-butyl-3-methylphenol), 1,1,3-tris (2-methyl-) is necessary because it is necessary to suppress yellowing when kneaded with a polycarbonate resin. 4-hydroxy-5-tert-butylphenyl) butane, 3,9-bis [2- {3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy} -1,1-dimethylethyl ] -2,4,8,10-tetraoxaspiro [5.5] undecane is preferred, especially 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 3 , 9-bis [2- {3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy} -1,1-dimethylethyl] -2,4,8,1 - tetraoxaspiro [5.5] undecane is preferred.

The content of the phenolic antioxidant used in the present invention may be appropriately selected and determined, but is usually 0.0001 to 0.5 parts by mass with respect to 100 parts by mass of the polycarbonate resin (A). 0.003 to 0.3 parts by mass is preferable, and 0.001 to 0.1 parts by mass is particularly preferable. If the content of the antioxidant is too small, the effect is insufficient. Conversely, if the content is too large, the molecular weight of the polycarbonate resin may be lowered or the hue may be lowered.

<(C-3) Release agent>
As the release agent that may be used in the present invention, at least one selected from aliphatic carboxylic acids, aliphatic carboxylic acid esters, and polysiloxane silicone oils is used. Among these, at least one selected from aliphatic carboxylic acids and aliphatic carboxylic acid esters is preferably used.

  Examples of the aliphatic carboxylic acid include saturated or unsaturated aliphatic monocarboxylic acid, dicarboxylic acid, and tricarboxylic acid. Here, the aliphatic carboxylic acid also includes an alicyclic carboxylic acid. Of these, preferred aliphatic carboxylic acids are mono- or dicarboxylic acids having 6 to 36 carbon atoms, and aliphatic saturated monocarboxylic acids having 6 to 36 carbon atoms are more preferred. Specific examples of such aliphatic carboxylic acids include palmitic acid, stearic acid, valeric acid, caproic acid, capric acid, lauric acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, melicic acid, tetratriacontanoic acid. , Montanic acid, glutaric acid, adipic acid, azelaic acid and the like.

  As the aliphatic carboxylic acid component constituting the aliphatic carboxylic acid ester, the same aliphatic carboxylic acid as that described above can be used. On the other hand, examples of the alcohol component constituting the aliphatic carboxylic acid ester include saturated or unsaturated monohydric alcohols and saturated or unsaturated polyhydric alcohols. These alcohols may have a substituent such as a fluorine atom or an aryl group. Of these alcohols, monovalent or polyvalent saturated alcohols having 30 or less carbon atoms are preferable, and aliphatic saturated monohydric alcohols or polyhydric alcohols having 30 or less carbon atoms are more preferable. Here, the aliphatic alcohol also includes an alicyclic alcohol.

  Specific examples of these alcohols include octanol, decanol, dodecanol, stearyl alcohol, behenyl alcohol, ethylene glycol, diethylene glycol, glycerin, pentaerythritol, 2,2-dihydroxyperfluoropropanol, neopentylene glycol, ditrimethylolpropane, dipentaerythritol. Etc. These aliphatic carboxylic acid esters may contain an aliphatic carboxylic acid and / or alcohol as impurities, and may be a mixture of a plurality of compounds.

  Specific examples of the aliphatic carboxylic acid ester include beeswax (mixture based on myricyl palmitate), stearyl stearate, behenyl behenate, octyldodecyl behenate, glycerin monopalmitate, glycerin monostearate, glycerin Examples thereof include distearate, glycerin tristearate, pentaerythritol monopalmitate, pentaerythritol monostearate, pentaerythritol distearate, pentaerythritol tristearate, and pentaerythritol tetrastearate.

  The compounding quantity of a mold release agent is 2 mass parts or less with respect to 100 mass parts of aromatic polycarbonate resin (A), Preferably it is 1 mass part or less. When the amount exceeds 2 parts by mass, there are problems such as degradation of hydrolysis resistance and mold contamination during injection molding. The release agent can be used alone or in combination.

  The mixing and kneading of the light diffusing resin composition of the present invention may be carried out by a method applied to ordinary thermoplastic resins, such as a ribbon blender, a Henschel mixer, a Banbury mixer, a drum tumbler, a single screw extruder, 2 It can be carried out by an axial screw extruder, a multi-screw extruder or the like. The temperature condition for kneading is usually 260 to 300 ° C.

The light diffusing resin composition of the present invention can be used for a general thermoplastic resin molding method, but from the point of productivity, injection molding, injection compression molding, extrusion molding from a pellet-shaped resin composition. Furthermore, vacuum molding, pressure molding, free blow molding, or the like from an extruded sheet-like molded product can be performed to obtain a target molded product.
The thickness of the molded product when used in the present invention is not particularly limited as long as the desired performance can be exhibited, but it is preferably 2 to 15 mm in practice. Even if the thickness of the molded product is too thin, the light diffusibility may not be sufficient or the light source may be seen through, which is not preferable. If it is too thick, the total light transmittance may be reduced, or the molded product may be reduced. Is not preferable because it may be too heavy and difficult to use.
The light diffusing member of the present invention includes a light diffusing molding device, for example, a cover or a lens for various display devices using an LED (light emitting diode element), for example, a lens or a lens cover for an LED signal lamp, an OA device, or a television. And the like, a light diffusion sheet of a liquid crystal display device, a light guide plate, a cover of a lighting device or a lighting fixture, a lighting signboard, a transmissive screen, and the like. In the present invention, the light source is particularly effective when used as a cover or a lens of a lighting fixture or a display fixture using an LED having a low luminous flux and high directivity.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example, unless the summary is exceeded. Moreover, the evaluation method in the Example and comparative example of the light diffusable resin composition of this invention, and the molding conditions of a test piece are as follows.
1) Average particle size of fine particles:
The weight distribution was measured at a pore size of 100 μm using a particle size distribution measuring device COULTER MULTISIZER manufactured by Beckman Coulter, and the arithmetic diameter was determined.
2) Test piece molding conditions:
A pellet preliminarily dried at 120 ° C. for 4 hours was molded into a test piece having a thickness of 3 mm at a cylinder temperature of 280 ° C., a molding cycle of 50 seconds and a mold temperature of 80 ° C. using a 150MIII type injection molding machine manufactured by Meiki Seisakusho.
3) Total light transmittance and haze:
Using Nippon Denshoku Industries Co., Ltd. haze meter NDH2000, the total light transmittance and haze of a 3 mm test piece were measured with the D65 light source.
4) Lightness L *:
Using a spectral color difference meter SE2000 manufactured by Nippon Denshoku Industries Co., Ltd., the lightness L * of a 3 mm test piece was measured with transmitted light from a C light source.
5) Visibility:
The LED was placed at a position 20 mm away from the back side of the 3 mm test piece, and it was confirmed whether the LED image could be recognized in a state where the LED was turned off from the surface. The case where the LED can be seen through is indicated as x, and the case where the LED cannot be seen through is indicated as ○.

[Example 1]
100 parts by weight of a polycarbonate resin (trade name: Iupilon (registered trademark) S-3000F) manufactured by Mitsubishi Engineering Plastics Co., Ltd., 0.2 parts by weight of ADEKA STAB LA-31 manufactured by ADEKA as a UV absorber, heat Made by ADEKA as a stabilizer, trade name: 0.05 part by mass of ADK STAB 2112, acrylic-styrene copolymer fine particles A (trade name: Gantz Pearl GSM-1261, manufactured by Ganz Kasei Co., Ltd.), 0.8 parts by mass) (sometimes abbreviated as “fine particles A”), pellets were produced with a single screw extruder having a screw diameter of 40 mm and a cylinder set temperature of 260 ° C., and test pieces were molded under the above conditions. Ten lots of light diffusing agents were obtained, pellets were prepared, and test pieces were prepared. Table 1 shows the average particle size and standard deviation of 10 lots of light diffusing agent. The total light transmittance, haze, and brightness were measured for a total of 50 test pieces for each lot, and the average value and standard deviation were obtained. Moreover, about haze, the ratio in the range of 80-90% was shown in Table 1 as a yield.

[Comparative Example 1]
Example except that 0.17 parts by mass of crosslinked acrylic fine particle B (manufactured by Ganz Kasei Co., Ltd., trade name: Ganzpearl GM-0630H) (hereinafter sometimes abbreviated as “fine particle B”) was blended as a light diffusing agent. 1 and the evaluation results are shown in Table 1.
From Table 1, it became clear that the light-diffusing resin composition of the present invention has high productivity and high lightness because the optical properties are stable.

[Examples 2 to 4, Comparative Examples 2 to 3]
Fine particles B were used as the light diffusing agent, the mixing ratio was as shown in Table 2, the total light transmittance and haze were measured for each of the five test pieces, and the average value was obtained. In addition, notched Charpy impact strength and visibility were evaluated and shown in Table 2.

As is clear from the above, the total light transmittance, haze, visibility, and Charpy impact strength were all well-balanced and excellent in the examples, whereas in the comparative example, none of them were balanced, There was no satisfactory light diffusing resin composition.

Claims (4)

A polymer fine particle (B) having a refractive index difference of 0.01 to 0.08 and an average particle size of 5 to 20 μm is contained between the polycarbonate resin (A) and the polycarbonate resin. A light diffusing polycarbonate resin composition, which is contained so that the blending coefficient represented by the product of the average particle diameter (μm) and the content (mass%) of the polymer fine particles is 6.2 to 11.8. 2. The light diffusing polycarbonate resin composition according to claim 1, wherein the polymer fine particles (B) are a cross-linked acrylic-styrene copolymer and have a refractive index of 1.52 to 1.57. The light diffusing polycarbonate resin according to claim 1 or 2, further comprising at least one of a benzotriazole ultraviolet absorber, a phosphorus heat stabilizer, and a phenolic antioxidant in the polycarbonate resin (A). Composition. A light diffusing member having a thickness of 2 to 15 mm, which is obtained by molding the resin composition according to any one of claims 1 to 3 and used for a lighting device or a display device using an LED (light emitting diode) as a light source.