JPH09306217A - Light diffuser for white fluorescent lamp cover - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve light source color reproducibility of an incandescent lamp and enable hue of the fluorescent lamp to be enhanced without greatly varying it by providing a light diffusion plate with its full light ray transmission of a specific percentage or more and with its absolute value of the mutual difference of each light ray transmission within specific percentage. SOLUTION: A crystal material that is a base material of a light plate is made of glass, methyl methacrylate resin, styrene resin or the like. The total light ray transmission of the light fluorescent plate is 40% or more, and if it is less than 40% the brightness of the fluorescent lamp cannot be utilized. If the absolute value of the mutual difference of each light ray transmission in plural wavelengths, i.e., of 436nm in blue, 544nm in green, and 612nm in red is not within a certain range, the light source color reproducibility of the fluorescent lamp is not improved. The range of each light ray transmission thereof is within 5%. Such a light diffusion plate does not greatly change color tone of the fluorescent lamp even if it is used as a cover material of the cool white fluorescent lamp of any hue.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a light diffusion plate for a white fluorescent lamp cover. Further, the present invention relates to a light diffusing plate for a white fluorescent lamp cover that does not impair the color tone of any color tone diffused and transmitted.

[0002]

2. Description of the Related Art Conventionally, as a material used for a cover of a white fluorescent lamp, a material such as glass or a transparent resin having an uneven surface or a transparent material having a refractive index different from that of the material is dispersed Allowed light diffusing materials have been used.

These light diffusing materials are now widely used for home lighting covers, commercial lighting signs and the like. However, due to the recent diversification of individual needs and the creative use of advertising / advertising means, the color tone of white fluorescent lamps used as a light source and the design itself have also diversified. ing.

The Illuminating Engineering Society No. 79, No. 12, 721
Page “Trends in multi-product fluorescent lamps” (December 1, 1995)
As described in the Japan Illumination Society), the tendency toward energy conservation has increased in Japan, and since 1977, three-wavelength fluorescent lamps have been used in large quantities. This three-wavelength fluorescent lamp is capable of emitting light of various color tones by changing the ratio of light intensity at three wavelengths, and is becoming the mainstream of the present fluorescent lamp.

[0005]

The three-wavelength fluorescent lamp is capable of emitting light with a wide range of color temperatures, and end users who live in the home, work place or office use fluorescent lamps of various color tones. are doing. However, recently, when a light diffusing cover is attached to these fluorescent lamps, the color of the transmitted light may change, resulting in an unnatural color. For example, high color temperature (about 6700K)
When only the fluorescent lamp of the lighting equipment containing the fluorescent lamp is replaced with one having a low color temperature (about 2800K) that creates a calm atmosphere, the color tone of the light transmitted through the lighting cover may change.

As a result of repeated studies on such a problem, what kind of white fluorescent light can be obtained by using a light diffusing plate as a white fluorescent lamp cover so that the difference in light transmittance of a specific wavelength falls within a certain range? The inventors have found that even if a lamp is used as a light source, the color of the light source can be reproduced, and the present invention has been completed.

[0007]

That is, the present invention has a total light transmittance of 40% or more and wavelengths of 436 nm and 544.
The light diffusion plate for a white fluorescent lamp cover is characterized in that the absolute value of the mutual difference between the respective light transmittances at 5 nm and 612 nm is within 5%. Hereinafter, the present invention will be described in detail.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The light diffusing plate in the present invention refers to a plate material obtained by adding a means for diffusing and transmitting light to a transparent material as a base material. As means for diffusing and transmitting light,
For example, it can be achieved by giving unevenness to the surface of the plate material or by dispersing a diffusing material having a refractive index different from that of the base material inside the plate material.

Examples of the transparent material as the base material include glass, methyl methacrylate resin, styrene resin, polycarbonate resin, vinyl chloride resin, polyethylene resin, polypropylene resin, polyester resin, and the like. A methyl methacrylate-based resin having excellent light resistance and easy to be thermoformed is preferable.

A methyl methacrylate resin is a methyl methacrylate unit of 50% by weight or more as a constitutional unit,
It is preferably 70% by weight or more, and as long as it contains 50% by weight or more of methyl methacrylate unit, a part of it is replaced with a monofunctional unsaturated monomer unit copolymerizable with methyl methacrylate. May be

Examples of the copolymerizable monofunctional unsaturated monomer include ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate and 2-methacrylic acid. Methacrylic acid esters such as hydroxyethyl; methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, acrylic acid 2
-Acrylic acid esters such as ethylhexyl and 2-hydroxyethyl acrylate; unsaturated acids such as methacrylic acid and acrylic acid; styrene, α-methylstyrene, acrylonitrile, methacrylonitrile, maleic anhydride, phenylmaleimide, cyclohexylmaleimide, etc. Is. The copolymer may further contain a glutaric anhydride unit and a glutarimide unit. Further, a blend of a diene rubber or an acrylic rubber with the above-mentioned polymer or copolymer may be used.

As means for diffusing and transmitting light, there are two methods of providing external light diffusivity and providing internal light diffusivity. In order to impart external light diffusibility, it is possible to impart irregularities to the surface of the plate material, and this method includes, for example, sandblasting or etching treatment when applied to a glass plate.

When it is applied to a resin plate, it is melted at a temperature at which the synthetic resin (base resin) constituting the resin plate is melted and kneaded as described in JP-B-50-2178 or JP-A-57-14650. It is carried out by dispersing fine resin particles or fine inorganic particles. The larger the absolute value of the difference in refractive index between the base resin and the fine particles to be dispersed, the more internal light diffusivity is imparted, and the light transmittance of the light diffusing plate tends to decrease.

There is also a method of forming irregularities directly on the surface of the resin plate. This is a so-called mat processing or embossing processing method. This method is a method in which a resin in a soft state is pressed and transferred to a hard material having irregularities, and the resin is cured. For example, the resin is extruded from a T-die into a plate shape, sandwiched between rolls, and cooled by so-called extrusion molding. A method for manufacturing a plate, which uses a roll with a mold, a so-called chevrolol, as described in JP-B-60-1185 and plastic material course [12] acrylic resin (published by Nikkan Kogyo Shimbun on March 25, 1970). There is. When a cast polymerization method or a continuous cast polymerization method is selected, it is possible to form irregularities corresponding to the resin surface by using cells having irregularities on the surface.

In addition, as a method of making unevenness on the surface of the resin plate, there is a method of stacking thin transparent films having unevenness. For example, as described in Japanese Patent Laid-Open No. 4-53839, a mask pattern that partially transmits ultraviolet rays is placed on an ultraviolet curable resin, partially cured by ultraviolet rays, and an uncured portion is removed by an alkali treatment to form an uneven pattern. And a method in which a liquid containing a matting agent is applied to the surface of the resin plate and cured.

The internal light diffusing property is imparted by dispersing a diffusing material having a refractive index different from that of the transparent material as the base material. Examples of the diffusing material to be dispersed include inorganic materials such as barium sulfate, calcium carbonate, glass, clay, talc, mica, titanium oxide, aluminum hydroxide, alumina, and zinc oxide. Further, organic materials can be used only when the base material is a resin, and styrene resin, acrylic resin, siloxane resin, fluorine resin and the like can be used.

There is no problem if these materials are continuously phase-separated from the substrate, but among the materials dispersed in these transparent substrates, those dispersed in the form of particles are preferable, Barium sulfate particles, aluminum hydroxide particles, mica particles, calcium carbonate particles, crosslinked styrene resin particles, crosslinked acrylic resin particles, and crosslinked siloxane resin particles are most excellent in reproducibility of light source color.

Barium sulfate refers to barite powder and what is referred to as precipitated barium sulfate, and precipitated barium sulfate is preferably used.

As aluminum hydroxide, in addition to ordinary aluminum hydroxide, alumina white containing crystal water can be preferably used.

Mica, which is usually called mica, is a silicic acid compound of aluminum, potassium, magnesium, sodium, iron, etc. When molded as a normal extruded plate, it has not only internal light diffusivity but also external light diffusivity. It can be given at the same time.

Calcium carbonate is preferably chemically synthesized, and calcium carbonate whose particle surface is coated with fatty acid can also be suitably used.

As the organic transparent material, crosslinked resin particles such as crosslinked styrene resin particles, crosslinked acrylic resin particles and crosslinked siloxane resin can be preferably used. The term "crosslinked resin particles" as used herein means particles having a gel fraction of 10% or more when dissolved in acetone.

The crosslinked styrenic resin particles include 50 to 99.9% by weight of a styrenic monomer unit and 0 to 49.9 of a monomer having one radical-polymerizable double bond in the molecule.
%, And 0.1 to 50% by weight of a monomer having at least two radically polymerizable double bonds in the molecule is mixed and polymerized.

The styrenic monomer is styrene and its derivatives. Examples of the styrene derivative include, but are not limited to, halogenated styrenes such as chlorostyrene and bromstyrene, vinyltoluene, and alkyl-substituted styrenes such as α-methylstyrene. Further, two or more kinds of the above styrene-based monomers may be used in combination.

[0025] One radically polymerizable double bond in the molecule
There are no particular restrictions on the monomer having the same as long as it is other than the styrene-based monomer component, but, for example, methyl methacrylate, ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, methacrylic acid Methacrylates such as benzyl, 2-ethylhexyl methacrylate, 2-hydroxyethyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate Acrylates such as 2-hydroxyethyl acrylate, and acrylonitrile. Of these, alkyl methacrylates such as methyl methacrylate are particularly preferred. Two or more kinds of the above monomers may be used in combination.

The monomer having at least two radically polymerizable double bonds in the molecule is a monomer that is copolymerizable with the above-mentioned monomer and excludes a conjugated diene. For example, 1,4-
Alkyldiol di (meth) acrylates such as butanediol di (meth) acrylate and neopentyl glycol di (meth) acrylate; ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) Alkylene glycol di (meth) acrylates such as acrylate, propylene glycol di (meth) acrylate, tetrapropylene glycol di (meth) acrylate; aromatic polyfunctional compounds such as divinylbenzene, diallyl phthalate; trimethylolpropane tri (meth) ) Polyacrylate (meth) acrylates such as acrylate and pentaerythritol tetra (meth) acrylate. Two or more kinds of these monomers may be used in combination.

The crosslinked acrylic resin particles include 50 to 99.9% by weight of an acrylic monomer unit and 0 to 4 monomers having one radical-polymerizable double bond in the molecule.
9.9% by weight, and 0.1 to 50% by weight of a monomer having at least two radically polymerizable double bonds in the molecule are mixed and polymerized.

Acrylic monomers include methyl methacrylate, ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl methacrylate, acrylic acid. Methyl,
Examples include ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, methacrylic acid, and acrylic acid.
Two or more of these monomers may be used in combination.

1 radical-polymerizable double bond in the molecule
There are no particular restrictions on the monomer having the number of components other than the above-mentioned acrylic monomer component, but for example, styrene and its derivatives. Examples of the styrene derivative include halogenated styrene such as chlorostyrene and bromstyrene, vinyltoluene, and alkyl-substituted styrene such as α-methylstyrene. Of these, styrene is particularly preferable. Two or more kinds of the above monomers may be used in combination.

The monomer having at least two radically polymerizable double bonds in the molecule is a monomer that is copolymerizable with the above-mentioned monomer and excludes a conjugated diene. It is selected from monomers such as (meth) acrylates, alkylene glycol di (meth) acrylates, aromatic polyfunctional compounds, and (meth) acrylates of polyhydric alcohols.

Both the cross-linked styrene resin particles and the cross-linked acrylic resin particles are polymerized with these components by a suspension polymerization method, a micro suspension polymerization method, an emulsion polymerization method, a dispersion polymerization method or the like to obtain the target particles. obtain.

The crosslinked siloxane-based resin is generally called a silicone rubber or a silicone resin, and means a solid one at room temperature. Siloxane polymers are mainly produced by hydrolysis and condensation of chlorosilanes. For example, a crosslinked siloxane polymer can be obtained by hydrolyzing and condensing chlorosilanes typified by dimethyldichlorosilane, diphenyldichlorosilane, phenylmethyldichlorosilane, methyltrichlorosilane, and phenyltrichlorosilane. Further, these crosslinked siloxane-based polymers are treated with benzoyl peroxide, -2,4-dichlorobenzoyl peroxide, -p-chlorobenzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl peroxide. -2,5-di (t-butylperoxy) hexane, such as by crosslinking with a peroxide,
Introducing a silanol group at the end of the polysiloxane compound,
It can also be produced by condensation-crosslinking with alkoxysilanes. Among these, a crosslinked siloxane-based polymer in which 2 to 3 organic groups are bonded per silicon atom is preferable.

In order to make the crosslinked siloxane resin into a particulate form, the crosslinked polymer is mechanically pulverized, or a specific linear organosiloxane block is contained as described in JP-A-59-68333. And a method for obtaining a spherical particle by curing a curable polymer or a curable polymer composition in a spray state, and a specific alkyltrialkoxysilane or its partial hydrolysis condensation as described in JP-A-60-13813. For example, a method of hydrolyzing and condensing the product into a spherical particle in an aqueous solution of ammonia or amines can be used.

In the present invention, the refractive index of the transparent material dispersed in the substrate is preferably such that the absolute value of the difference in the refractive index from the substrate is within 0.15. The total light transmittance increases as the absolute value of the refractive index difference between the two approaches 0, and decreases as the absolute value increases. If this value exceeds 0.15, the total light transmittance becomes 40% or less even if added in a small amount, and it becomes difficult to diffuse light while transmitting light, and it becomes difficult to use as a fluorescent lamp cover material.

The refractive index of the inorganic particles greatly differs depending on the crystal form and the content of impurities. The refractive index of barium sulfate is around 1.64, the refractive index of aluminum hydroxide is 1.47 to 1.59, and the refractive index of mica is mica. The refractive index is 1.55-1.
59, the refractive index of calcium carbonate is in the range of 1.48 to 1.66. A material having an appropriate difference from the refractive index of the substrate is selected from these.

The refractive index of the crosslinked styrenic polymer varies depending on the constituent components of the styrenic polymer.
It is about 1.61. In general, the refractive index tends to increase as the amount of the monomer having a phenyl group increases and as the amount of the halogenated monomer increases. A material having an appropriate difference from the refractive index of the base resin is selected from these.

The refractive index of the crosslinked acrylic polymer varies depending on the constituent components of the acrylic polymer, but is 1.46.
It is about 1.55. In general, the refractive index tends to increase as the amount of the monomer having a phenyl group increases and as the amount of the halogenated monomer increases. A material having an appropriate difference from the refractive index of the base resin is selected from these.

The refractive index of the crosslinked siloxane-based polymer varies depending on the constituent components of the siloxane-based polymer.
It is about 40 to 1.47. Generally, as the number of phenyl groups in the siloxane-based polymer increases, and as the number of organic groups directly connected to silicon atoms increases, the refractive index tends to increase.
A material having an appropriate difference from the refractive index of the base resin is selected from these.

The particle size of these particles is from 1 on a weight average basis.
50 μm is preferred. Those having an absolute value of the refractive index difference of less than 15 μm with the base material of 0.02 or more are suitable for imparting internal light diffusivity, and an absolute value of the refractive index difference with the base material of 0.1 μm or more is 0. Those less than 02 are suitable for imparting external light diffusivity. When the absolute value of the refractive index difference with the substrate is 15 μm or more and 0.02 or more, the internal light diffusivity is
It is possible to impart external light diffusivity at the same time.

These particles are added to a transparent material as a base material in an amount of 0 to
20 parts by weight is contained. If it exceeds 20 parts by weight, the mechanical strength of the light diffusion plate tends to be weak. Of course, there is no problem even if two or more kinds of these particles are used in combination, or in combination with the above-mentioned roll transfer method with a mold as long as the condition of the light transmittance is satisfied. Regarding the method of dispersion, it may be dispersed uniformly in the thickness direction of the base resin, or may be locally distributed in the surface layer or in the center.

The total light transmittance of the light diffusing plate in the present invention is 40% or more. The total light transmittance is based on JIS K-7105. If it is less than 40%, the brightness of the fluorescent lamp of the light source cannot be fully utilized, which is not preferable. The total light transmittance greatly changes depending on how the light diffusivity is imparted. When only external light diffusivity is applied to the plate material, it does not decrease significantly, but when internal light diffusivity is applied, the transmittance decreases as the absolute value of the refractive index difference with the transparent material to be dispersed increases. . Of course, it depends not only on the refractive index of the material to be dispersed but also on the form of dispersion (particle size etc.) and the amount of dispersion, so several trials will be made to set the optimum region.

In the present invention, the light transmittance of light passing through the light diffusion plate at a specific wavelength is extremely important. The three-wavelength fluorescent lamp produces a color by appropriately balancing the light intensities in the three regions of the blue region, the green region, and the red region.
If the light in the two areas is not diffused and transmitted evenly, the color tone of the fluorescent lamp itself and the color tone when passing through the cover will look different, which creates a feeling of strangeness.

In the present invention, 436 nm, 544 nm,
The wavelength of 612 nm is a wavelength that represents “blue”, “green”, and “red”, respectively, and the absolute value of the mutual difference between the light transmittances at these wavelengths must be within a certain fixed range. The transmittances of these wavelengths are measured by connecting an integrating sphere to a spectrophotometer in accordance with JIS Z 8722 “Measuring method of object color”, “Measuring method of transmitting object”.

To improve the light source color reproducibility of a fluorescent lamp,
The absolute value of the difference between the light transmittances at the three wavelengths is within 5%, and more preferably, the absolute value of the difference between the light transmittances at the wavelengths of 436 nm and 612 nm is within 3%. The absolute value of the difference in light transmittance between 544 nm and 436 nm is preferably within 1%.

As elements for controlling the light transmittance in these specific wavelength regions, (1) addition of a light diffusing dispersion material having a form (particle diameter) close to the wavelength region of light,
(2) Color tone of the light diffusing dispersion material itself or the base material itself,
There are four items: (3) addition of a specific wavelength conversion material and (4) addition of a specific wavelength absorption material.

As a diffusing material having a form (particle diameter) close to the wavelength region of light, for example, in the case of particles, it means particles having a particle diameter of less than 1 μm, and many diffusing materials at this level are dispersed. Since the transmitted light becomes reddish as it is, the wavelength is based on the standard material (a light diffusion plate in which a transparent material is transparent and a diffusion material containing almost no particles with a particle size of less than 1 μm is dispersed). 436nm and 544n
The light transmittance at m tends to decrease.

The color tone of the diffusing material itself or the base material itself is an influence of the so-called color tone of the material itself. Compared with the standard material, if the transmitted light of the material used is bluish, the wavelengths are 544 nm and 612 nm. The light transmittance at
Light transmittance at wavelengths of 436 nm and 612 nm if greenish, and wavelengths of 436 nm and 612 if reddish.
The light transmittance in nm falls.

Typical examples of the specific wavelength converting material include "fluorescent brightening agents". The addition of a fluorescent whitening agent has an effect of converting light in the ultraviolet region into bluish visible light, and slightly increases the light transmittance at a wavelength of 436 nm as compared with the standard material.

Specific wavelength conversion materials include, for example, fluorescein, thioflavin, eosin, rhodamine and its derivatives, coumarin, imidazole, oxazole,
Triazole, carbazole, pyridine, naphthalic acid,
Examples thereof include imidazolone and diaminostilbene sulfonic acid derivatives. Of these, oxazole-based ones can be preferably used.

The dispersion amount of these wavelength conversion materials in the light diffusion plate is about 1 to 100 ppm. If it is less than 1 ppm, the effect is small, and if it exceeds 100 ppm, the plate material itself becomes a bluish material. Of course, if the original plate before dispersion is within the range of the target light transmittance, it may not be dispersed.

Dyes and pigments exist as the specific wavelength absorbing material. Of course, the wavelength of 544
nm and 612 nm, the light transmittances at wavelengths of 436 nm and 612 nm by the addition of the green dye / pigment, and the wavelengths of 436 nm and 54 at the wavelengths of 436 nm and 612 nm by the addition of the red dye / pigment.
The light transmittance at 4 nm decreases.

The specific wavelength absorbing material is not particularly limited as long as it is a material usually used for coloring. For example, the blue dyes and pigments are ultramarine blue, navy blue, cobalt blue, phthalocyanine blue, anthraquinone blue and indium. Dunslen blue, cobalt violet, mineral violet, anthraquinone violet, dioxazine violet, etc., green pigments such as chrome green, phthalocyanine green, etc., red dyes and pigments, red lead yellow lead, chrome vermilion, cadmium orange, Pyrazolone orange, red iron oxide, cadmium red, permanent red 4R, pyrazolone red, lake red C,
Carmine 6B, Mercury Red, Pigment Scarlet 3B, Bordeaux 10B, Bon Maroon, Thioindigo Maroon, Oil Red, Permanent Red F5
R, quinacridone red, etc. are mentioned.

The dispersion amount of these wavelength absorbing materials in the light diffusing plate is about 1 to 50 ppm. If it is less than 1 ppm, the effect is small, and if it exceeds 50 ppm, the plate material itself becomes a material having a strong dye / pigment color tone. Of course, if the original plate before dispersion is within the range of the target light transmittance, it may not be dispersed.

Materials are adjusted by combining these elements so as to meet the above conditions. Generally, when a light diffusing dispersion material is added to a transparent material, particles having a particle diameter of 1 μm or less are obtained. Since it is difficult to completely cut it, (light transmittance at a wavelength of 612 nm)> (wavelength 5
The light transmittance at 44 nm)> (light transmittance at a wavelength of 436 nm) tends to be satisfied. To correct this, it is easy to disperse a fluorescent whitening agent to increase the light transmittance at a wavelength of 436 nm, or to disperse a blue dye or pigment to lower the light transmittance at a wavelength of 612 nm or 544 nm. The desired light diffusion plate can be obtained.

The light diffusing plate of the present invention is a so-called sheet,
It is called a board. Further, the shape of the plate may be uniform in thickness, may have a thickness distribution by secondary molding like a lighting cover, or may be curved. The thickness is not particularly limited, but 0.1 mm to 10 mm
It is a degree.

A well-known mixing / molding method is used to form a plate-like body by incorporating a dispersion material such as a light-diffusing transparent material, a wavelength converting material or a wavelength absorbing material into a transparent base material which constitutes the light diffusing plate. Can be used.

For example, when the transparent substrate is a thermoplastic resin,
There is a method of melt-kneading each component, and the melt-kneading includes a method of using a kneading device such as a generally used uniaxial or biaxial extruder and various kneaders. It is also possible to make the plate material in one step by using the molding method described below. Further, when the transparent substrate is a methyl methacrylate resin or a styrene resin, the dispersion material is mixed with a syrup containing a monomer constituting the methyl methacrylate resin or the styrene resin and a partial polymer thereof, There is also a method of performing plate polymerization by cast polymerization or continuous cast polymerization.

Further, in order to use the thermoplastic resin composition as a light diffusing plate, it is melt-kneaded by a uniaxial or biaxial extruder or the like, and then T
It can be processed into a plate shape through a die or a roll unit (with a mold), can be processed into a light diffusion plate of a specific shape by using a special die such as profile extrusion, or can be formed into a plate shape or complicated by injection molding or press molding. There is a well-known method of forming a light diffusion plate having a different shape.

There is no particular problem even if well-known additives such as a light stabilizer, an ultraviolet absorber, an antioxidant, a release agent, a flame retardant and an antistatic agent are dispersed in the light diffusion plate of the present invention.

[0060]

The light diffusing plate of the present invention is excellent in light source color reproducibility of a white fluorescent lamp and can be used as a cover material for a white fluorescent lamp of any color tone without significantly changing the color tone of the fluorescent lamp. It is possible to produce. Therefore, the light diffusing plate can be suitably used for various light source cover applications such as an illumination cover using a fluorescent lamp, an illumination signboard, a light diffusing plate of a transmissive display, and a light emitting switch button.

[0061]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. The evaluation method is as follows. (1) Weight average particle size: Light diffraction scattering particle size analyzer (Microtrack particle size analyzer Model 9220 FR manufactured by Nikkiso Co., Ltd.)
It was measured in A) and the value of D50 was taken as the average particle size. (2) Total light transmittance: In accordance with JIS K-7105, Poic integrating sphere haze meter (SEP-HS-30D manufactured by Nippon Seimitsu Optical Co., Ltd.)
Was measured by (3) Concealment and light diffusivity: transmitted light intensity with a transmission angle of 0 degrees (I ₀ ) by vertically incident light, transmitted light intensity with a transmission angle of 5 degrees (I ₅ ) with vertically incident light, transmission angle by vertically incident light The transmitted light intensity (I ₇₀ ) of 70 degrees was measured using an automatic goniophotometer GP-1R manufactured by Murakami Color Research Laboratory Co., Ltd., and I ₅ / I ₀ was made to be concealing property, and I ₇₀ / I _{0 was made.} Was made light diffusive. (4) Light transmittance at each wavelength: In accordance with JIS Z-8722, an integrating sphere is connected to a self-recording spectrophotometer (Hitachi Ltd. 330 type) to measure the light transmittance at wavelengths of 436 nm, 544 nm, and 612 nm. It was measured. (5) Visual judgment: compact fluorescent lamp (Hitachi, Ltd. E
FG15EX-L (color temperature 2800K), EFG15EX-D (color temperature 6700K) 2
Type) was turned on, and a light diffuser plate was installed at a position 10 cm away from the fluorescent lamp, and those that did not have an unnatural color tone were marked with ◯, and those with an unnatural color tone were marked with x.

Examples 1 to 5 and Comparative Examples 1 to 3 Methacrylic resin beads (SUMIPEX E
XA, Sumitomo Chemical Co., Ltd., refractive index 1.49), and calcium carbonate particles (CS 3N-D, as a light diffusing dispersion material)
Calceed Co., Ltd., average particle size 9 μm, refractive index 1.5
1), calcium carbonate particles (Cypron A, manufactured by Cypro Kasei Co., Ltd., average particle size 8 μm, refractive index 1.51), titanium oxide particles (R-830, manufactured by Ishihara Sangyo Co., Ltd., average particle size 0.2 μm)
m, refractive index 2.6) or crosslinked silicone resin particles (DY33-7
19, manufactured by Toray Dow Corning Silicone Co., Ltd., average particle diameter 2 μm, refractive index 1.42), oxazole-based 4,4-bis (5-methyl-2-benzoxazolyl) stilbene (white flow) as a fluorescent whitening agent PSN Sumitomo Chemical Co., Ltd.
As a blue pigment, ultramarine blue (PPD-572 Sumika Color Co., Ltd.)
(Manufactured by Tanabe Plastic Co., Ltd., screw diameter)
A light diffusing plate having a resin temperature of 265 ° C., a thickness of 2 mm, and a width of 22 cm was prepared through 40 mm, uniaxial), a T-die, and three polishing rolls. Table 2 shows the evaluation results.

Example 6 100 parts by weight of the same methacrylic resin beads as in Example 1, 2 parts by weight of calcium carbonate particles as a light diffusing dispersion material and mica particles (Suzolite Mica 350-K1, manufactured by Marietta Co., average particle size) Material A was prepared by mixing 5 parts by weight of 20 μm, refractive index 1.60) and 7 parts by weight of crosslinked siloxane resin particles (Tospearl 120, manufactured by Toshiba Silicone Co., Ltd., average particle diameter 2 μm, refractive index 1.43) with a Henschel mixer. And In 100 parts by weight of the same methacrylic resin beads as in Example 1, calcium carbonate particles were used as a light diffusing dispersion material and a wind classifier (TC-15N manufactured by Nisshin Engineering Co., Ltd.).
Material B was prepared by mixing 2 parts by weight of the powder having an average particle size of 3 μm with 30 parts of the same fluorescent whitening agent as in Example 1 with a Henschel mixer. Material A was supplied to an extruder (manufactured by Tanabe Plastic Co., Ltd., screw diameter 20 mm, uniaxial), Material B was supplied to the same extruder as in Example 1, both molten materials were integrated by a feed block, and the resin temperature was 265 ° C.
With a T-die and 3 rolls (polishing roll / texture roll / polishing roll), material B is present at the center of the plate and material A is present on both sides of the plate with a thickness of about 80 μm and a thickness of 1.8 mm. A light diffusion plate with a width of 20 cm was created. Table 2 shows the evaluation results.

Examples 7 to 8 100 parts by weight of the same methacrylic resin beads as in Example 1 and crosslinked methacrylic resin beads (SUMIPEX XC1A, manufactured by Sumitomo Chemical Co., Ltd., average particle diameter 35 μm, refraction) as a light diffusing dispersion material. Ratio 1.49) 10 parts by weight and cross-linked styrene-based particles (Fine Pearl PB3006, Sumitomo Chemical Co., Ltd., average particle size 6 μm, refractive index 1.59) are 0 parts by weight, 1.7 parts by weight, respectively, the same as in Example 1. After mixing 30 ppm of the blue pigment with a Henschel mixer, a light diffusion plate having a resin temperature of 265 ° C., a thickness of 2 mm, and a width of 20 cm was prepared using the same extruder as in Example 1. Table 2 shows the evaluation results.

Example 9 0.1 parts by weight of 2,2'-azobis (isobutyronitrile) per 100 parts by weight of methyl methacrylate, barium sulfate particles (BMH-D, manufactured by Sakai Chemical Industry Co., Ltd., average particles) Diameter 3 μm,
Refractive index 1.64) 2.1 parts by weight, aluminum hydroxide particles (CL
303, Sumitomo Chemical Co., Ltd., average particle diameter 4 μm, refractive index 1.57) 0.8 parts by weight, 25 pp of the same optical brightener as in Example 1
m, anthraquinone violet blue dye (Waxoli
ne Purple AS, manufactured by ICI), 2.5 ppm was added, mixed and dispersed, and then deaerated under a reduced pressure of 700 mmHg for about 30 minutes to obtain 300 ×.
A polyvinyl chloride gasket was placed between two glass pieces of 300 x 10 mm, and the mixture was poured into a glass cell with a gap of 2 mm and polymerized in a water bath at 70 ° C for 2 hours.
Heat treatment was performed in an air oven at 120 ° C. for 1 hour to obtain a light diffusion plate. Table 2 shows the evaluation results.

[0066]

[Table 1]

[0067]

[Table 2]

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location G02B 5/02 G02B 5/02 B

Claims (4)

[Claims] 1. A white fluorescent lamp cover having a total light transmittance of 40% or more and an absolute value of a mutual difference of light transmittances at wavelengths of 436 nm, 544 nm and 612 nm within 5%. Light diffusion plate. 2. The absolute value of the difference in light transmittance between the wavelengths of 436 nm and 612 nm is within 3%, and the wavelength of 544n
The absolute value of the difference in light transmittance between m and 436 nm is 1%
The light diffusing plate for a white fluorescent lamp cover according to claim 1, which is within the range. 3. The light diffuser plate for a white fluorescent lamp cover according to claim 1, wherein the transparent material serving as the base material is a methyl methacrylate resin. 4. The transparent material as a base material is a methyl methacrylate resin, and the diffusing material dispersed in the base material is barium sulfate particles, aluminum hydroxide particles, mica particles, calcium carbonate particles, crosslinked styrene resin. At least one selected from the group consisting of particles, crosslinked siloxane-based resin particles, and crosslinked acrylic-based resin particles, further comprising a fluorescent whitening agent and / or a blue dye / pigment dispersed therein. The light diffusing plate for a white fluorescent lamp cover according to claim 1 or 2.