JP6358867B2 - Light diffusing polycarbonate resin composition and light diffusing member using the same - Google Patents

Description

  The present invention provides a light diffusing member in which a decrease in light amount is suppressed when installed on a light exit surface of a lighting device, and glare (hereinafter sometimes simply referred to as glare) when the lighting device is directly viewed is reduced. The present invention relates to a light diffusing polycarbonate resin composition that can be used and a light diffusing member using the same.

  In recent years, from the viewpoint of ecology, LED light bulbs and fluorescent tube shapes that use light-emitting diodes (hereinafter referred to as LEDs) that have low power consumption, vibration resistance, ultra-brightness, and stable light emission for a long period of time as light sources for lighting LED lighting devices such as LED tubes have come to be used. While the LED has the above-mentioned advantages, it is a point light source and has high brightness, and thus it is easy to feel glare and glare due to light emitted from the light source. Therefore, when using an LED, it is necessary to reduce glare and glare caused by the emitted light, and it is necessary to efficiently diffuse the emitted light to improve the function as a lighting device. Therefore, in the LED lighting device, it is attempted to reduce glare and glare by the emitted light by means such as diffusing the emitted light using a light diffusing member for the illumination cover.

  As the light diffusing member, a thermoplastic resin has been used more widely than before because molding processability and freedom of product shape are easily obtained, and in particular, it has an excellent balance of mechanical properties, thermal properties, optical properties, and the like. A polycarbonate resin is preferably used.

  For example, Patent Document 1 discloses that acryl-styrene copolymer fine particles 0.1 to 5 having a refractive index of 1.505 to 1.575 and a weight average particle diameter of 0.5 to 30 μm are added to 100 parts by weight of a polycarbonate resin. A light diffusing resin composition containing 0.0 part by weight is disclosed. Further, Patent Document 2 contains polymer fine particles having a refractive index difference of 0.01 to 0.08 and an average particle size of 5 to 20 μm between the polycarbonate resin and the polycarbonate resin. A light diffusing resin composition comprising a resin so that a blending coefficient represented by a product of an average particle diameter (μm) and a content (mass%) of polymer fine particles is 6.2 to 11.8. Is disclosed. When a light diffusing member made of these light diffusing resin compositions is used in an LED lighting device, the LED lighting device is suppressed with excessive brightness that causes discomfort and difficulty in seeing an object.

  On the other hand, when these light diffusing members are used in an LED lighting device, the amount of light is reduced. When the light diffusing member described in Patent Document 1 or Patent Document 2 is used in an LED lighting device, the total light transmittance is reduced to about 89.5 to 91%, and when a general polycarbonate resin composition is used. In comparison, the total light transmittance is high, but it is difficult to say that the decrease in the amount of light is sufficiently suppressed.

  In some cases, a lens member is installed in the vicinity of the point light source, and the light emitted from the point light source is collected, so that the light emitted from the illumination device can be scattered far away. In such a case, since the light distribution angle of the light entering the light diffusing member is narrowed, even if a conventional light diffusing member including the diffusing plate described in the above patent document is used, There has been a problem that the condensed light collecting effect is greatly reduced, and light cannot be emitted far away.

  On the other hand, in the light source unit disclosed in Patent Document 3, unlike the light diffusing member of Patent Document 1 and Patent Document 2, a light diffusing member having a low haze is used. The dazzling suppression effect is inferior.

  From the above, the reduction in glare and the decrease in the amount of light are trade-offs.

JP 2005-247999 A JP 2010-229193 A JP 2012-186022 A

  An object of the present invention is to provide a light diffusing polycarbonate resin composition that can be a light diffusing member in which a decrease in the amount of light is suppressed and the glare is reduced, and a light diffusing member using the same.

  The inventor adjusts the refractive index, the mass average particle diameter, and the content of the polymer fine particles contained in the light diffusing polycarbonate resin composition within a predetermined range, thereby sufficiently suppressing the decrease in the amount of light, And it discovered that the light-diffusion member which reduced the glare greatly can be produced, and came to complete this invention.

  The light diffusing polycarbonate resin composition of the present invention comprises a polycarbonate resin and polymer fine particles having a refractive index difference of 0.01 to 0.08 and a mass average particle diameter of 6 μm to 12 μm. And the content of the polymer fine particles with respect to 100 parts by mass of the polycarbonate resin is 2 parts by mass or more and 8 parts by mass or less. The polymer fine particles are preferably acrylic-styrene copolymer fine particles.

  Further, in a light diffusing member having a thickness of 3 mm formed using the light diffusing polycarbonate resin composition, the light diffusibility in which the value of P × Q of the haze percentage P% and the total light transmittance Q% is 8000 or more. A polycarbonate resin composition is preferable, and a light diffusing polycarbonate resin composition having a total light transmittance of 92% or more and a haze of 90% or more is more preferable.

  The present invention also includes a light diffusing member formed using the light diffusing polycarbonate resin composition, and the relative transmittance measured by the method described in the specification of the light diffusing member is 2. It is 20 or less and the light distribution angle is 15 ° or more and 70 ° or less.

  The light diffusing member preferably has a haze of 90% or more.

  The light diffusing member preferably has a total light transmittance of 90% or more.

  The light diffusing member preferably has a thickness of 0.4 to 5 mm.

  When a light diffusing member formed using the light diffusing resin composition of the present invention is used in an illuminating device, it is possible to greatly reduce glare despite a reduction in the amount of light. In addition, when the light diffusing member of the present invention is used for a device in which a lens member is provided in the vicinity of the point light source or on the light exit surface to collect the light emitted from the point light source, the light is condensed by the lens member. The above effects are exhibited without greatly changing the light distribution angle. Therefore, it can be used in a wide range of applications where it is necessary to reduce glare in a form that suppresses the decrease in the amount of light, such as a lens or lens cover of a signal lamp using LED, a lighting cover, a lighting signboard, a transmissive screen, various displays, It can be used for various illumination-related devices such as light diffusion sheets and light guide plates of liquid crystal display devices. In particular, in a display device using an LED as a light source, the visibility is very excellent. In the following description, the various illumination devices may be simply referred to as illumination devices.

FIG. 1 is a diagram showing the relationship between relative transmittance and maximum luminance rate when the light diffusing members of Examples 1-1 and 1-2 and Comparative Examples 1-1 to 1-4 are used. FIG. 2 is a diagram showing the relationship between the light distribution angle and the maximum luminance rate when the light diffusing members of Examples 1-1 and 1-2 and Comparative Examples 1-1 to 1-4 are used. FIG. 3 is a diagram showing the relationship between relative transmittance and illuminance directly below when the light diffusing members of Examples 1-1 and 1-2 and Comparative Examples 1-1 to 1-4 are used. FIG. 4 is a diagram illustrating the relationship between the light distribution angle and the illuminance directly below when the light diffusing members of Examples 1-1 and 1-2 and Comparative Examples 1-1 to 1-4 are used. FIG. 5 is a diagram illustrating the relationship between the light receiving angle and the relative transmittance in the illumination devices of Examples 2-1 and 2-2, Comparative Examples 2-1 and 2-2, and the reference example. FIG. 6 is an apparatus in which the way light travels can be easily observed. 7A is a photograph showing how light travels when the light diffusing member B is used in the apparatus of FIG. 6, and FIG. 7B is a photograph using the light diffusing member D in the apparatus of FIG. It is a photograph showing how the light travels in the case. FIG. 7C is a photograph showing how the light travels when the light diffusing member B is used with the rear projection plate removed from the apparatus of FIG. 6, and FIG. 7D is a photograph of FIG. It is a photograph which shows how to advance the light at the time of using the light-diffusion member D in the state which removed the back projection board from the apparatus.

  The light diffusing polycarbonate resin composition of the present invention (hereinafter referred to as a light diffusing resin composition) contains a polycarbonate resin and polymer fine particles.

<Polycarbonate resin>
The polycarbonate resin used in the present invention is a polymer obtained by an interfacial polymerization method of an aromatic dihydroxy compound and phosgene, or a polymer obtained by a transesterification reaction of an aromatic dihydroxy compound and a carbonic acid diester. May be used as part of the aromatic dihydroxy compound. The polycarbonate resin used in the present invention may be linear or branched. Moreover, the polycarbonate resin used by this invention may be individual, or 2 or more types of mixtures may be sufficient as it.

  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), and the like. Bis (4-hydroxyphenyl) alkane-based dihydroxy compounds; 2,2-bis (4-hydroxy-3,5-dibromophenyl) propane (tetrabromobisphenol A), 2,2-bis (4-hydroxy-3, Bis (4-hydroxyphenyl) alkane-based dihydroxy compounds containing halogen such as 5-dichlorophenyl) propane (tetrachlorobisphenol A); 1,1-bis (4-hydroxyphenyl) cyclohexane; hydroquinone; resorcinol; 4,4-dihydroxy Diphenyl and so on , Preferably bis (4-hydroxyphenyl) alkane-based dihydroxy compound or bis containing halogen (4-hydroxyphenyl) alkane-based dihydroxy compound, more preferably bisphenol A. These aromatic dihydroxy compounds may be used alone or in combination.

  In order to obtain a branched polycarbonate resin, 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-chloroisatin bisphenol, 5,7-dichloro Triaromatic polyhydroxy compounds such as isatin bisphenol and 5-bromoisatin bisphenol are aromatic dihydroxylated. What is necessary is just to use it as a part of compound.The usage-amount in the case of using a polyhydroxy compound is about 0.1-2 mol% of the said aromatic dihydroxy compound, for example.

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

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

<Polymer fine particles>
The polymer fine particles used in the present invention may be polymer fine particles having a refractive index and a mass average particle diameter within the ranges described below. Examples of the polymer fine particles include acryl-styrene copolymer fine particles, acryl- Examples thereof include butadiene-styrene (ABS) copolymer fine particles, and acrylic-styrene copolymer fine particles are preferable.

  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. Examples of acrylic monomers include methacrylate monomers such as methyl methacrylate and ethyl methacrylate, acrylate monomers such as methyl acrylate and ethyl acrylate, and acrylamide. Examples of styrene monomers include styrene and α-methylstyrene. And vinyltoluene. Moreover, what copolymerized the other monomer as needed by using the said monomer as a main component may be used. Examples of the crosslinking agent include commonly used ones such as ethylene glycol dimethacrylate, divinylbenzene, 1,6-hexanediol dimethacrylate, trimethylpropane trimethacrylate, trimethylpropane trimethacrylate, trimethylpropane triacrylate, and the like. These multifunctional monomers can be used.

  The mass average particle diameter of the polymer fine particles used in the present invention is 6 μm or more and 12 μm or less, preferably 6 μm or more and 10 μm or less, more preferably 7 μm or more and 9 μm or less. When the particle diameter is less than 6 μm, the number of particles used is relatively large, and thus there is a possibility that the variation in haze of the light diffusing member becomes large. On the other hand, when the thickness exceeds 12 μm, the number of particles used is relatively reduced, which may reduce the strength of the light diffusing member.

  The polymer fine particles used in the present invention are added in an amount of 2 parts by mass or more and 8 parts by mass or less, preferably 2 parts by mass or more and 6 parts by mass or less, more preferably 2 parts by mass with respect to 100 parts by mass of the polycarbonate resin. The amount is 4 parts by mass or less. When the addition amount of the polymer fine particles is less than 2 parts by mass, the addition amount of the polymer fine particles becomes a small amount, so that the haze variation of the light diffusing member obtained using the light diffusing resin composition becomes large. When the amount exceeds mass parts, the amount of polymer fine particles added becomes large and the strength of the light diffusing member is lowered.

  The difference between the refractive index of the polymer fine particles and the refractive index of the polycarbonate resin is 0.01 or more and 0.08 or less, preferably 0.02 or more and 0.06 or less, more preferably 0.03 or more, 0 .05 or less.

  When the polymer fine particle is an acrylic-styrene copolymer, the refractive index of the polymer fine particle can be adjusted by changing the mass ratio of the acrylic monomer to the styrene monomer in the range of 99: 1 to 1:99. When a large amount of acrylic monomer is used, the refractive index decreases, and when a large amount of styrene monomer is used, the refractive index increases. The molar ratio of the acrylic monomer to the styrene monomer is preferably 7: 3 to 2: 8, more preferably 6: 4 to 3: 7. 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 polymer fine particles and the polycarbonate resin composition The difference in refractive index is too wide, and the glare of the LED light source is conspicuous and the visibility is lowered. When the polymer fine particles are acrylic-styrene copolymer fine particles, the refractive index of the acrylic-styrene copolymer fine particles is preferably 1.52-1.57, more preferably 1.53-1. 56, more preferably 1.54 to 1.56.

  Adjustment of the copolymerization ratio of acrylic monomer and styrene monomer varies depending on the type of monomer used. For example, when methyl methacrylate is used as the acrylic monomer and styrene is used as the styrene monomer, the acrylic monomer When the molar ratio of styrene monomer is 7: 3, the refractive index of the polymer fine particle is about 1.52, and when the molar ratio of acrylic monomer and styrene monomer is 3: 7, the refractive index of the polymer fine particle is 1 .56.

  The structure of the acrylic-styrene copolymer fine particles is not particularly limited, but solid fine particles are preferable. When the acrylic-styrene copolymer is a fine particle having a two-layer structure of a core part and a shell part, the shell part is an acrylic-styrene copolymer, and the particle diameter and refractive index satisfy the scope of the present invention. If it does, it can be used. In that case, the core part is preferably made of polymethyl methacrylate, silicone, or the like having a lower refractive index than the shell part.

  Commercially available products may be used as the acrylic-styrene copolymer fine particles, and examples of the above-mentioned commercially available products include Aika Kogyo's Gantzpearl (registered trademark) series and Staphyloid (registered trademark) series. It is done.

<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.

  The mixing and kneading of the light diffusing resin composition of the present invention can 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, It can be carried out by a twin screw extruder, a multi-screw extruder or the like. The temperature condition for kneading is usually preferably 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. It is also possible to form a light diffusing member by performing vacuum forming, pressure forming, free blow molding, or the like from an extruded sheet-like molded product.

(Optical characteristics of light diffusing resin composition)
In the light diffusing member having a thickness of 3 mm formed using the light diffusing resin composition of the present invention, the haze is preferably 90% or more, more preferably 91% or more, and further preferably 92% or more. If the haze is less than 90%, dazzling may not be reduced. Although the upper limit of haze is not specifically limited, 99% or less is preferable.

  In the light diffusing member having a thickness of 3 mm formed using the light diffusing resin composition of the present invention, the total light transmittance is preferably 92% or more, more preferably 93% or more, and further preferably 94% or more. It is. If the total light transmittance is less than 92%, the amount of light and the illuminance directly below may decrease. The upper limit of the total light transmittance is not particularly limited, but is preferably 98% or less.

  In the light diffusing member having a thickness of 3 mm formed using the light diffusing resin composition of the present invention, the value of P × Q of the haze percentage P% and the total light transmittance Q% is preferably 8000 or more, more preferably. Is 8200 or more, more preferably 8400 or more, and most preferably 8600 or more. If the value of P × Q is less than 8000, dazzling may not be reduced, or the amount of light and illuminance directly below may be reduced. The upper limit of the value of P × Q is not particularly limited, but 9000 or less is preferable.

(Optical characteristics of light diffusing member)
The light diffusing member formed using the light diffusing resin composition of the present invention has a relative transmittance of 2 to 20 measured by the method described in the specification, and an orientation angle of 15 ° to 70 °. It is preferable to satisfy simultaneously.

  The relative transmittance of the light diffusing member formed using the light diffusing resin composition of the present invention is preferably 2 or more, more preferably 3 or more, and further preferably 4 or more. Further, the relative transmittance is preferably 20 or less, more preferably 18 or less, and further preferably 15 or less. If the relative transmittance is less than 2, the illuminance directly below may decrease, and if the relative transmittance exceeds 20, the glare may not be reduced. The method for measuring the relative transmittance will be described in detail in Examples.

  The light distribution angle of the light diffusing member formed using the light diffusing resin composition of the present invention is preferably 15 ° or more, more preferably 18 ° or more, still more preferably 20 ° or more, most The angle is preferably 22 ° or more. The light distribution angle is preferably 70 ° or less, more preferably 60 ° or less, and further preferably 50 ° or less. If the light distribution angle is less than 15 °, glare may not be reduced, and if the light distribution angle exceeds 70 °, the illuminance directly below may decrease. Further, it is not preferable because the light distribution angle of the light collected by the lens member changes greatly.

  The light distribution angle in the present specification is 100% of the transmitted light intensity of the straight light passing through the sample in the state of the light receiving angle of 0 ° measured using the variable angle spectrocolorimetry system GCMS-4 type described in the embodiment. , The angle with respect to straight light when the intensity of transmitted light passing through the sample is 50% is represented by the full width.

  In the present invention, the evaluation of glare is performed by selecting all light sources when the number of light sources is 1 to 5, and arbitrarily selecting five light sources when the number of light sources is 6 or more. It evaluates using the value which becomes the maximum brightness among the brightness values. The maximum luminance rate is a value representing the ratio of the maximum luminance in the lighting device with the light diffusing member to the luminance in the lighting device without the light diffusing member as a percentage. Are described in detail in the Examples.

  The haze of the light diffusing member formed using the light diffusing resin composition of the present invention is preferably 90% or more, more preferably 91% or more, and further preferably 92% or more. If the haze is less than 90%, dazzling may not be reduced. Although the upper limit of haze is not specifically limited, 99% or less is preferable.

  The total light transmittance of the light diffusing member formed using the light diffusing resin composition of the present invention is preferably 90% or more, more preferably 92% or more, still more preferably 93% or more, and most preferably. Is 94% or more. If the total light transmittance is less than 90%, the amount of light and the illuminance directly below may decrease. The upper limit of the total light transmittance is not particularly limited, but is preferably 98% or less.

  The value P × Q of the haze percentage P% and the total light transmittance Q% of the light diffusing member formed using the light diffusing resin composition of the present invention is preferably 8000 or more, more preferably 8200 or more. More preferably, it is 8400 or more, particularly preferably 8600 or more, and most preferably 8800 or more. If the value of P × Q is less than 8000, dazzling may not be reduced, or the amount of light and illuminance directly below may be reduced. The upper limit of the value of P × Q is not particularly limited, but 9000 or less is preferable.

(Thickness of light diffusion member)
The light diffusing member of the present invention is formed using the light diffusing resin composition, and the thickness of the light diffusing member is preferably from 0.4 mm to 5 mm, more preferably from 0.5 mm to 3 mm. Since the light diffusing member formed using the light diffusing resin composition has a thickness within the above range, various physical properties such as relative transmittance, light distribution angle, and total light transmittance do not greatly change. The thickness of the light diffusing member can be changed according to the above.

(Shape of light diffusion member)
The shape of the light diffusing member of the present invention is not limited, and may be a flat plate or a non-planar shape such as a curved surface shape. Further, the surface shape of the light diffusing member is not limited, and may be a smooth surface or a surface having irregularities such as a satin shape or a mat shape. The method for imparting irregularities to the surface is not particularly limited. For example, a surface shape imparting layer is laminated, and the surface shape imparting layer is peeled off from the light diffusing member after a certain period of time, or the shape is imparted when manufacturing the light diffusing member. Examples thereof include a method of imparting irregularities to the surface of the light diffusing member using a mold.

(Method for producing light diffusing member)
The light diffusing member of the present invention can be produced by the above-mentioned known production methods, and examples thereof include a solution method, a melting method, and a calendar method.

(Use of light diffusion member)
The light diffusing member of the present invention includes, for example, a lens or cover for various display devices using LEDs such as a lens of an LED signal lamp or a lens cover, a display such as an OA device or a television, a light diffusing sheet of a liquid crystal display device, a light guide. Used for light plates, lighting devices, lighting device covers, lighting signs, transmissive screens, and the like. In particular, the light diffusing member of the present invention is effective when used as a light source for a cover or a lens of an LED illumination device or a display device using an LED having a low luminous flux and high directivity.

(Installation location and usage of light diffusing member)
The light diffusing member of the present invention only needs to be installed in the direction in which light is emitted from the point light source. For example, in a device in which a lens member is provided near the point light source to collect light emitted from the point light source. The lens member may be installed on the outer surface (on the light source side), or the lens member may be installed on the inner surface (the light source side).

  As the lighting device member, only one light diffusing member of the present invention may be used, or a plurality of light diffusing members may be used. In the case of using a plurality of sheets, the light diffusing members may be used in an overlapping manner or may be used separately. Moreover, you may use in combination with another light-diffusion member or a lens member. For example, a light diffusing member of the present invention is superimposed on a light exit surface of a lens member such as a lens film for a device in which a lens member is provided in the vicinity of the point light source to collect light emitted from the point light source. In this case, it is possible to suppress the occurrence of side lobe, which is a defect of the lens member, and the condensing effect is maintained to some extent, and while suppressing the decrease in the light amount, the glare caused by the structure of the lens member Interference spots can also be improved.

(Other uses of light diffusion members)
In addition, although the apparatus etc. which used LED were described above, the light-diffusion member of this invention was also used for the illuminating device using the point light source which consists of electroluminescence, a light bulb, a krypton ball, etc. besides LED. Can be used as a member for a lighting device in which a decrease in brightness is suppressed and glare is reduced.

  The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to the following examples, and may be appropriately modified and implemented within a range that can meet the purpose described above and below. All of which are within the scope of the present invention. The physical property measurement methods for the samples obtained in each Example and Comparative Example are as follows.

(1) Total light transmittance and haze Based on JISK7105, the total light transmittance and haze of the sample were measured with the D65 light source using the Nippon Denshoku haze meter NDH2000.

(2) Relative transmittance The transmitted light intensity was measured using a variable angle spectrocolorimetric system GCMS-4 type (manufactured by Murakami Color Research Laboratory Co., Ltd., variable angle spectrophotometer GPS-2 type).
First, the GCMS-4 type transmitted light diffusion standard plate (opal glass) is calibrated, and the transmitted light intensity T at a wavelength of 550 nm at a light receiving angle of 0 ° of the transmitted light diffusion standard plate is set as a reference (1 .000). The transmission diffusion standard plate had a transmittance of 0.3535 at a wavelength of 550 nm when the air layer was set to 1.000 by integrating sphere spectroscopic measurement.
Next, transmission measurement mode, light incident angle: 0 ° (film normal direction), light receiving angle: −90 ° to 90 °, 5 ° pitch (polar angle from film normal, azimuth angle is horizontal), light source : D65, field of view: Fixed to the sample stage so that the main light diffusion direction of the sample is horizontal under the conditions of 2 ° (the deviation between the axis of the sample table and the axis of the main light diffusion direction is allowed up to about 20 ° The transmitted light intensity at a wavelength of 550 nm at each light receiving angle was measured. The tilt angle was set to 0 °, and when the surface roughness was different on both surfaces of the sample, the sample was fixed in the direction in which light entered from the surface with the lower surface roughness and measured.
Then, the relative transmittance was calculated by dividing the value of transmitted light intensity at a wavelength of 550 nm at each light receiving angle by the value of transmitted light intensity T. Each sample was measured three times to calculate the relative transmittance, and the average value was obtained.

(3) Light distribution angle Using the variable angle spectrophotometric color measurement system GCMS-4, when the transmitted light intensity at a wavelength of 550 nm of the straight light passing through the sample (light receiving angle: 0 °) is 100%, it passes through the sample. The angle (total value width) with respect to straight light when the transmitted light intensity at a wavelength of 550 nm is 50% was determined as the light distribution angle.

(4) Illuminance Using a variable angle illuminometer (“ZERO-ONE” manufactured by Highland) so that the center point of the illumination device and the center point of the sample table coincide with each other on the drive-type sample table Install and measure the illuminance in two directions on the equator line and meridian line on the condition of 5mm pitch from the illumination device light emitting surface and the illuminometer light receiving surface: 1000mm, variable angle range: -90 ° to 90 ° went. Switching between the equator line and the meridian was performed by rotating the sample stage by 90 ° about a straight line passing through the center point of the sample stage and perpendicular to the sample stage. The illuminance was measured in a dark room, and the measurement was started 30 minutes after the lighting device was turned on. The illuminance at an angle of 0 ° was taken as the direct illuminance. When the illuminance differs in the axial direction, the average value is displayed.

(5) Total luminous flux The total luminous flux was calculated from the illuminance data measured by the above method using the calculation software attached to the variable angle illuminometer ("ZERO-ONE" manufactured by Highland).

(6) Maximum luminance rate The luminance was measured by the following method. The center point of the illumination device and the center point of the sample table coincide with each other on the sample table of the driving system of the two-dimensional 3CCD color luminance measuring device ("RISA-COLOR / ONE-II" manufactured by Highland). installed. Then, the lighting device was turned on and observed from directly above, and five point light sources in the light source portion were arbitrarily selected, and the luminance at the position directly above the light point source was measured. When the number of point light sources was less than 5, the luminance was measured for all light sources. The luminance was measured using a two-dimensional 3CCD color luminance measuring device (“RISA-COLOR / ONE-II” manufactured by Highland Corporation), and L1 was the one with the highest luminance. Moreover, the brightness | luminance when not installing a light-diffusion member was measured using the said two-dimensional 3CCD color brightness | luminance measuring apparatus, and the brightness | luminance was set to L2. The maximum luminance ratio was obtained by dividing the maximum luminance L1 when the light diffusing member was installed by the luminance L2 when the light diffusing member was not installed and expressed as a percentage.
When the spot of the light point source was visible, the brightness of the spot portion was measured. However, when the diffusivity of the light diffusing member is high, the spread of the light source spot becomes large, and the spot overlapped with the spot of the adjacent light point source may become invisible. In that case, the position of the light point source spot before the light diffusing member was set in advance, and the brightness at the position directly above the light point source was measured by measuring the brightness at that position. The luminance was measured in a dark room, and the measurement was started 30 minutes after the lighting device was turned on.

(Light diffusion member A)
The light diffusing member A was produced by the following manufacturing method. 10075 parts by weight of a polycarbonate resin having a refractive index of 1.59 (Iupilon (registered trademark) E-2000FN manufactured by Mitsubishi Engineering Plastics) and 0.075 parts by weight of a phosphorus-based heat stabilizer (Irgaphos (registered trademark) 168 manufactured by BASF) , Oxazole-based fluorescent brightener (Nikka Flow OB manufactured by Nippon Chemical Industry Co., Ltd.) 0.003 parts by mass, acrylic-styrene copolymer fine particles having a mass average particle diameter of 8 μm and a refractive index of 1.55 (Ganzu Pearl manufactured by Aika Kogyo Co., Ltd.) (Registered trademark) GSM-0855) 2.3 parts by mass, a vent and a gear pump were attached, and a 1.0 mm thick diffusion plate was extruded using a sheet extruder having three rolls. The relative transmittance, light distribution angle, total light transmittance, and haze of the light diffusing member A were measured, and the measurement results are shown in Table 1.

(Light diffusion member B)
The light diffusing member B was formed by extrusion of a diffusing plate having a thickness of 2.0 mm in the same manner as the light diffusing member A. The relative transmittance, light distribution angle, total light transmittance, and haze of the light diffusing member B were measured, and the measurement results are shown in Table 1.

(Light diffusion member C)
The light diffusing member C was produced by the following manufacturing method. 10075 parts by weight of a polycarbonate resin having a refractive index of 1.59 (Iupilon (registered trademark) E-2000FN manufactured by Mitsubishi Engineering Plastics) and 0.075 parts by weight of a phosphorus-based heat stabilizer (Irgaphos (registered trademark) 168 manufactured by BASF) , 0.5 parts by mass of silicone fine particles having a mass average particle diameter of 2.0 μm and a refractive index of 1.44 (Tospearl (registered trademark) 120 manufactured by Momentive Performance Materials) 3 parts with a vent and gear pump A diffusion plate having a thickness of 1.0 mm was extruded using a sheet extruder having a roll of 1 mm. The relative transmittance, light distribution angle, total light transmittance, and haze of the light diffusing member C were measured, and the measurement results are shown in Table 1.

(Light diffusion member D)
The light diffusing member D was formed by extrusion of a diffusing plate having a thickness of 2.0 mm in the same manner as the light diffusing member C. The relative transmittance, light distribution angle, total light transmittance, and haze of the light diffusing member D were measured, and the measurement results are shown in Table 1.

(Light diffusion member E)
As the light diffusing member E, a 2 mm thick methacrylic extruded plate Komoglass (registered trademark) DFA2 was used. The relative transmittance, light distribution angle, total light transmittance, and haze of the light diffusing member E were measured. The measurement results are shown in Table 1.

(Light diffusion member F)
As the light diffusion member F, Lightup (registered trademark) LSE100 manufactured by Kimoto Co., Ltd. having a thickness of 0.1 mm was used. The relative transmittance, light distribution angle, total light transmittance, and haze of the light diffusing member F were measured. The measurement results are shown in Table 1.

(Relationship between thickness of light diffusing member and optical characteristics)
In the light diffusion member B having a thickness of 2.0 mm, except that the content of Gantzpearl (registered trademark) GSM-0855 with respect to 100 parts by mass of Iupilon (registered trademark) E-2000FN was changed from 0.5 parts by mass to 8 parts by mass. In the same manner as the light diffusing member A, 10 types of light diffusing members differing only in the content of the acrylic-styrene copolymer fine particles were obtained. And about 10 types of said light-diffusion members, haze, the total light transmittance, and the light distribution angle were measured, and it showed in Table 3.

  Extrusion molding was performed by the same method as that of the light diffusing member A to produce a light diffusing member G having a thickness of 3.0 mm. In the light diffusing member G having a thickness of 3.0 mm, except that the content of Gantzpearl (registered trademark) GSM-0855 with respect to 100 parts by mass of Iupilon (registered trademark) E-2000FN was changed from 0.5 parts by mass to 8 parts by mass. In the same manner as the light diffusing member A, 10 types of light diffusing members differing only in the content of the acrylic-styrene copolymer fine particles were obtained. And about 10 types of said light-diffusion members, haze, the total light transmittance, and the light distribution angle were measured, and it showed in Table 3.

  In the light diffusion member B having a thickness of 2.0 mm, Gantzpearl (registered trademark) GSM-0855 was changed to acrylic fine particles having a mass average particle diameter of 8.0 μm and a refractive index of 1.49, and Iupilon (registered trademark) E-2000FN100. The acrylic fine particles were formed in the same manner as the light diffusing member A except that the content of the acrylic fine particles having a mass average particle diameter of 8.0 μm and a refractive index of 1.49 with respect to mass parts was changed from 0.1 parts by mass to 5 parts by mass. Eleven types of light diffusing members differing only in content were obtained. And about 11 types of said light-diffusion members, haze, a total light transmittance, and the light distribution angle were measured, and it showed in Table 4.

  In the light diffusing member G having a thickness of 3.0 mm, Gantzpearl (registered trademark) GSM-0855 was changed to acrylic fine particles having a mass average particle size of 8.0 μm and a refractive index of 1.49, and Iupilon (registered trademark) E-2000FN100. The acrylic fine particles were formed in the same manner as the light diffusing member A except that the content of the acrylic fine particles having a mass average particle diameter of 8.0 μm and a refractive index of 1.49 with respect to mass parts was changed from 0.1 parts by mass to 5 parts by mass. Eleven types of light diffusing members differing only in content were obtained. And about 11 types of said light-diffusion members, haze, a total light transmittance, and the light distribution angle were measured, and it showed in Table 4.

  In Table 4, compared with the case of Table 3, the amount of change in the total light transmittance is increased by increasing the thickness of the light diffusing member from 2.0 mm to 3.0 mm.

  Thus, the light diffusing member formed using the light diffusing resin composition of the present invention is characterized in that the optical properties of the light diffusing member hardly change even if the thickness of the light diffusing member is different. Have. Therefore, even if the thickness of the light diffusing member required by the illumination device is different, the light diffusing resin composition of the present invention can be used to reduce the light amount simply by changing the thickness of the light diffusing member. Since a light diffusing member that is sufficiently suppressed and has greatly reduced glare can be produced, cost reduction is possible.

(Example 1-1)
The Fresnel lens fitted in the light emission part of E-CORE (registered trademark) LED unit LDF5N-WGX53 / 2 manufactured by Toshiba Lighting & Technology was removed, and a light diffusing member A was provided instead. Using the LED unit provided with the light diffusing member A, the illuminance directly below, the total luminous flux, and the maximum luminance rate were measured. The measurement results are shown in Table 2. FIG. 1 shows the relationship between the relative transmittance and the maximum luminance rate, FIG. 2 shows the relationship between the light distribution angle and the maximum luminance rate, FIG. 3 shows the relationship between the relative transmittance and the illuminance directly below, and FIG. The relationship with the illuminance directly below is shown in FIG.

(Example 1-2)
In Example 1-1, a light diffusing member B was provided instead of the light diffusing member A. Similar to Example 1-1, the illuminance directly below, the total luminous flux, and the maximum luminance ratio were measured. The measurement results are shown in Table 2. FIG. 1 shows the relationship between the relative transmittance and the maximum luminance rate, FIG. 2 shows the relationship between the light distribution angle and the maximum luminance rate, FIG. 3 shows the relationship between the relative transmittance and the illuminance directly below, and FIG. The relationship with the illuminance directly below is shown in FIG.

(Comparative Examples 1-1 to 1-4)
In Example 1-1, instead of the light diffusing member A, light diffusing members C to F were provided. Similar to Example 1-1, the illuminance directly below, the total luminous flux, and the maximum luminance ratio were measured. The measurement results are shown in Table 2. FIG. 1 shows the relationship between the relative transmittance and the maximum luminance rate, FIG. 2 shows the relationship between the light distribution angle and the maximum luminance rate, FIG. 3 shows the relationship between the relative transmittance and the illuminance directly below, and FIG. The relationship with the illuminance directly below is shown in FIG.

(Example 2-1)
The light diffusing member A was provided on the outer surface (on the opposite side of the light source) of the Fresnel lens fitted in the light exit portion of the E-CORE (registered trademark) LED unit LDF5N-WGX53 / 2 manufactured by Toshiba Lighting & Technology. The transmitted light intensity was measured by the above measurement method, and the relative transmittance at each light receiving angle when the transmitted light intensity at a light receiving angle of 0 ° was set to 1 was obtained. FIG. 5 shows the relationship between the light receiving angle and the relative transmittance.

(Example 2-2)
In Example 2-1, a light diffusing member B was provided instead of the light diffusing member A. The relative transmittance at each light receiving angle was determined in the same manner as in Example 2-1. FIG. 5 shows the relationship between the light receiving angle and the relative transmittance.

(Comparative Example 2-1 and Comparative Example 2-2)
In Example 2-1, instead of the light diffusing member A, light diffusing members C and D were provided. The relative transmittance at each light receiving angle was determined in the same manner as in Example 2-1. FIG. 5 shows the relationship between the light receiving angle and the relative transmittance.

(Reference example)
Example 2-1 without providing a light diffusing member on the light source side (inner surface) of the Fresnel lens fitted in the light exit portion of the E-CORE (registered trademark) LED unit LDF5N-WGX53 / 2 manufactured by Toshiba Lighting & Technology Corp. Similarly, the relative transmittance at each light receiving angle was obtained. FIG. 5 shows the relationship between the light receiving angle and the relative transmittance.

  From FIG. 1 to FIG. 4, by satisfying the preferable range of the optical characteristics of the light diffusing member used in the present invention, it is possible to achieve both the characteristics of the antinomy event, which is the object of the present invention, that is to suppress the decrease in light quantity and to reduce the glare. I was able to. 1 to 4 also show the criticality of the optical characteristics of the light diffusing member used in the present invention. Furthermore, it was shown from FIG. 5 that a narrow light distribution angle distribution collected by the Fresnel lens is maintained by using a light diffusing member that satisfies a preferable range of optical characteristics.

(How light travels when a light diffusing member is used)
Using an apparatus in which the way of light as shown in FIG. 6 can be easily visually observed, the way of light when the light diffusing member B is used and the way of light when the light diffusing member D is used are measured. did. The apparatus of FIG. 6 is provided so as to be parallel to the lower projection plate 1, the rear projection plate 2 provided so as to be perpendicular to the lower projection plate 1, and perpendicular to the rear projection plate 2. Further, a light diffusion member (light diffusion plate) 3 described in the embodiment of the present invention and a hole having a diameter of 5 mm in the plate thickness direction provided on the anti-lower projection plate 1 side so as to be parallel to the light diffusion member 3 Is made up of a reflective plate 4 having a gap and an LED flashlight 5 made by GENTOS provided on the side of the anti-light diffusing member 3 so that outgoing light travels perpendicularly to the reflective plate 4. When this device is used, the light emitted from the flashlight 5 passes through the hole of the reflecting plate 4, then passes through the light diffusing member 3, and finally reaches the lower projection plate 1. In addition, the rear projection plate 2 is provided at a position that does not hinder the progress of the light reaching the lower projection plate 1, and the rear projection plate 2 is removable.

  As can be seen from FIGS. 7A to 7D, when the light diffusing member B of Example 1-2 is used, the lower projection plate 1 is brightly illuminated, and a decrease in the amount of light is suppressed. Has been. On the other hand, when the light diffusing member D of Comparative Example 1-2 is used, the lower projection plate 1 is not brightly illuminated, the light has diffused, and the amount of light is significantly reduced.

  By using the light diffusing member formed using the light diffusing resin composition of the present invention for an illuminating device, a decrease in the amount of light emitted from the illuminating device was suppressed, and the glare could be reduced. In addition, even when the light diffusing member of the present invention is used for a device in which a lens member is installed in the vicinity of the point light source and the light emitted from the point light source is condensed, the light collecting effect is maintained to some extent Furthermore, the decrease in the amount of light was suppressed, and the glare could be reduced. The light diffusing member of the present invention is applied to various lighting devices such as a lens or lens cover of a signal lamp using LEDs, a lighting cover, a lighting signboard, a transmissive screen, various displays, a light diffusing sheet of a liquid crystal display device, and a light guide plate. Applicable.

Claims (6)

A refractive index difference between the polycarbonate resin and the polycarbonate resin is 0.01 to 0.08 and acrylic-styrene copolymer fine particles having a mass average particle diameter of 6 μm to 10 μm.
A top Symbol light diffusing polycarbonate resin composition content is more than 2.5 parts by mass or more 2 parts by weight of the fine particles to the polycarbonate resin 100 parts by weight,
The light diffusing member having a thickness of 3 mm formed using the light diffusing polycarbonate resin composition has a total light transmittance of 92% or more and a haze of 92% or more,
Angle with respect to the straight light when the intensity of the transmitted light passing through the light diffusing member becomes 50% when the transmitted light intensity at a wavelength of 550 nm of the straight light passing through the light diffusing member having a thickness of 3 mm is 100% Is a light diffusing polycarbonate resin composition characterized by being 36 ° or more . In the light diffusing member having a thickness of 3 mm formed using the light diffusing polycarbonate resin composition according to claim 1, the value of P × Q of the haze percentage P% and the total light transmittance Q% is 8000 or more. A light diffusing polycarbonate resin composition. A light diffusing member which is formed by using a light diffusing polycarbonate resin composition according to claim 1 or 2, wavelength 550nm at the light receiving angle 0 ° as measured by variable angle spectroscopic colorimetry system of the light diffusing member light diffusing member, wherein the relative permeability obtained by dividing the value of the transmitted light intensity values of the transmitted light intensity of the wavelength 550nm of the light-receiving angle 0 ° of opal glass is 2 to 20. 4. The light diffusing member according to claim 3 , wherein the haze is 90% or more. The light diffusing member according to claim 3 or 4 , wherein the total light transmittance is 90% or more. The light diffusion member according to any one of claims 3 to 5 , wherein the light diffusion member has a thickness of 0.4 to 5 mm.