JPH09147613A - Tone holding sheet for light source protective cover - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve light transmissivity and light diffusion without losing an original tone by using a sheet made of a transparent resin as a main component, containing white fine particles not melted by its forming temperature and containing white fine particles each having a particular form and a particle distribution for indicating a particular chromaticity coordinates SOLUTION: A tone holding sheet is made of a transparent resin as a main component so as to be prevented from being melted by its forming temperature, formed in a roughly cubic shape and contain more than one kind of white type fine particles with weight average particle diameter set to within the range of 0.1 to 30μm. The measured value of the chromaticity coordinates of a transmitted light using a JIS/Z-8720 standard light source satisfies the following two expressions: 0.001<=1xL-xT1<=0.015... (1), 0.005<=1yL-YT1<=0.02... (2). Herein, xL and yL are the chromaticity coordinates of the standard light source, xT and YT are the chromtiacity coordinates of the transmitted light of the sheet. Preferably, in the JIS/Z-8720 standard light source, measuring of the chromaticity coordinates of a reflected light satisfies the following expression: 0.005<=1xL-XR1$0.03, 0.005←L-yR1$0.035. Herein, XR<=yR is the chromaticity coordinates of the reflected light of the sheet.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cover sheet for protecting an exposed light source, and more specifically, it does not impair the original color tone of the light source when the light source of various color tones is turned on.
The present invention relates to a sheet for a light source protection cover that does not impair the color tone due to a shadow of a light source being turned off when it is turned off, and has excellent light transmittance and light diffusion.

[0002]

2. Description of the Related Art An example of using a light source protective cover for sufficiently transmitting light from a light source to supply light source energy and at the same time diffusing the light uniformly to prevent the light source from directly contacting the eyes of an observer. , Home and facility lighting covers, various displays, display signs, etc. Conventionally,
These members are required to have a function of being able to be molded into any shape and capable of transmitting and diffusing the light amount of the light source more, and high transmission and high diffusion in which fine particles with different refractive indexes are dispersed in transparent resin. The investigation of the functional materials is being conducted.
For example, a resin composition in which an inorganic powder such as glass is dispersed in a methacrylic resin (JP-A-54-155244).
Also disclosed is a resin plate (JP-A-1-172801) in which a transparent resin contains a silicone resin having a specific structure and particle size.

[0003]

The light diffusing resin disclosed by these prior arts makes maximum use of the brightness of the light source as a light source protection cover and has a uniform brightness without the contour of the light source being transparent. The purpose is to obtain a surface with a light source, and no consideration has been made regarding the color tone as a light source protection cover material. In other words, the color tone of the above two materials is so-called milky white, but when used as a light source cover, the original color tone of the light source changes when the light source is turned on, or when the light source is turned off, the shadow of the internal light source is projected to darken the color tone. There are problems such as damage and deterioration of appearance.

In recent years, lighting equipment has been increasingly used with a low-power, high-luminance type light source in a social environment where the effective use of energy is called for, but at the same time, it has been attracting attention as a means for creating a comfortable space. It is positioned as a product that enriches the living environment, such as harmony with indoor interiors, directing at gallery facilities and stores, and improving the landscape by illuminating buildings. In particular, there is a great need for highly-directive lighting, and a wide variety of light sources with various color tones are presented, which does not impair the color tone of these light sources.
There is a demand for a light source protection cover material that can maintain the same color tone even when the light is off.

The present invention relates to a cover sheet for protecting an exposed light source, and more specifically, it does not impair the original color tone of the light source when the light source of various color tones is turned on, and the original color tone is obtained by casting a shadow of the light source when turned off. Another object of the present invention is to provide a color tone-retaining sheet for a light source protection cover, which is excellent in light transmissivity and light diffusivity without being damaged.

[0006]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventor has mainly made transparent resin,
A sheet containing white fine particles having a specific shape and a weight average particle diameter is a color of transmitted light measured using three types of standard light sources (A, C, D65) specified in JIS Z-8720. The present invention has been completed by finding that the above object can be achieved only when a specific relationship is satisfied with respect to the degree coordinate.

That is, the present invention is mainly composed of a transparent resin, does not melt at the molding temperature of the transparent resin, has a substantially cubic shape, and has a weight average particle diameter of 0.1 to 30 μm. Contains more than one type of white fine particles, and JIS / Z-
When the chromaticity coordinates of transmitted light are measured using the standard light source defined by 8720, all the measured values of each standard light source simultaneously satisfy the following formulas (I) and (II). It is a color retention sheet for a protective cover.

0.001 ≦ | x _L −x _T | ≦ 0.015 (I) 0.0005 ≦ | y _L −y _T | ≦ 0.02 (II) (where x _L , Y _L is the chromaticity coordinate of the standard illuminant, x _T ,
y _T represents the chromaticity coordinate of the transmitted light of the sheet. ) In the above invention, when the chromaticity coordinates of reflected light are measured using a standard light source defined by JIS Z-8720, all measured values at each light source are expressed by the following formulas (III) and (I
It is more preferable to satisfy V) at the same time.

0.005 ≦ | x _L −x _R | ≦ 0.03 (III) 0.0005 ≦ | y _L −y _R | ≦ 0.035 (IV) (where x _L , Y _L is the chromaticity coordinate of the standard light source, x _R ,
y _R represents the chromaticity coordinate of the reflected light of the sheet. )

Further, in the present invention, it is preferably applied that the optical brightening agent is contained in an amount of 0.001 to 0.1 part by weight.

The above-mentioned sheet of the present invention is used as a base material layer (A).
A structure in which the surface layer (B) mainly composed of a transparent resin is provided on one side or both sides is also preferably applied.

Further, in the present invention, a methacrylic resin is preferably applied as the transparent resin.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, the expression "mainly composed of a transparent resin" means that 50% by weight or more of the transparent resin is contained. Further, the transparent resin used in the present invention,
Haze measured according to JIS K-7105 is 10%
It is defined as a substance that: Specifically, methacrylic resin, polycarbonate resin, polystyrene resin, styrene-methyl methacrylate copolymer resin, styrene-
Butadiene copolymer resin, polyvinyl chloride resin and the like. What is particularly preferably adopted as the transparent resin is
Methacrylic resin.

The methacrylic resin which can be used in the present invention includes a resin mainly containing methyl methacrylate, which includes a homopolymer of methyl methacrylate, a copolymer of methyl methacrylate and one or more monomers copolymerizable therewith. Polymers, heat resistant acrylic resins, low hygroscopic acrylic resins and the like are included. These may be used alone or may be blended. Further, as a monomer copolymerizable with methyl methacrylate, methyl methacrylate and methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, butyl acrylate, acrylonitrile, acrylic acid, methacrylic acid, vinyl pyridine, vinyl morpholine, vinyl pyridone tetrahydro Furfuryl acrylate, N, N-dimethylaminoethyl acrylate, N, N-dimethylacrylamide, 2-hydroxyacrylate, ethylene glycol monoacrylate, glycerin monoacrylate, maleic anhydride, styrene, and α-methylstyrene are exemplified. In order to maintain transparency and simultaneously provide impact resistance, an impact-resistant acrylic resin is used, and its rubber elastic body is disclosed in JP-A-53-55854 and JP-A-55-55854.
Nos. 94917 and 61-32346. Briefly, it is a multi-stage polymer produced by a multi-stage sequential polymerization method in which an elastic layer and an inelastic layer are alternately formed around an acrylic polymer core material.

It is necessary that the white fine particles used in the present invention do not melt at the molding temperature of the transparent resin. By not melting the transparent resin at the molding temperature, the shape such as the shape and particle size of the white fine particles is maintained when dispersed in the transparent resin, and a sheet for a light source protection cover that exhibits stable color tone and optical characteristics is obtained. can get.

The shape of the white fine particles used in the present invention is required to be substantially cubic. That is,
It is preferable that the stereoscopic image of the white fine particles is observed by a general optical microscope or an electron microscope, and that substantially cubic particles are present in a proportion of 60% or more of all particles in the observed image. . However, a substantially cube is composed of six surfaces having almost the same area, the angles between these surfaces may be right angles or oblique angles, and the shape in which the sides of the boundary between the surfaces are slightly shaved,
It is defined to include a rounded shape in which the corners of the apex are slightly shaved. When the shape of the white fine particles is substantially cubic, the difference in the color tone of the transmitted light and the reflected light when dispersed in the transparent resin becomes small, and the original color tone of the light source is expressed by various light sources, A sheet for a light source protection cover having a surprising effect is obtained.

The white fine particles used in the present invention must have a weight average particle diameter in the range of 0.1 to 30 μm. The particle size distribution of the white fine particles can be measured by a known light transmission type sedimentation particle size distribution measuring method or the like, and the weight average particle size can be determined from the obtained particle size distribution. If the weight average particle size does not fall within the range of 0.1 to 30 μm,
The particles can be used if they are classified so as to fall within the above range. The weight average particle diameter of the white fine particles is 0.1 to 3
When it is in the range of 0 μm, the visible light is effectively refracted and reflected at the interface of each particle in the transparent resin, and a light source protective cover sheet excellent in light transmittance and light diffusion can be obtained.

Specific examples of the white fine particles used in the present invention include calcium carbonate, calcium fluoride, potassium fluoride, barium sulfate, magnesium sulfate, titanium oxide,
Inorganic substance particles such as potassium titanate, aluminum hydroxide, magnesium hydroxide, crystalline silica, amorphous silica, glass flakes, glass fibers, alumina, mica, talc and clay, and crosslinked styrene polymer, crosslinked acrylic heavy Organic compound particles such as coalesced, cross-linked styrene-acrylic copolymers, cross-linked styrene-butadiene copolymers, cross-linked siloxane polymers, cross-linked urethane polymers and the like can be mentioned, and these may be used alone. However, two or more kinds may be used in combination.

The amount of the white fine particles used in the present invention is preferably 0.1 to 30 parts by weight based on 100 parts by weight of the transparent resin, and the total content of the one or more kinds of white fine particles is 0.1 to 30 parts by weight. It is preferably 1 to 20 parts by weight. When in this range, the optical properties when dispersed in a transparent resin,
In particular, the color tone can be adjusted without extremely lowering the total light transmittance, and a preferable light source protective cover sheet can be obtained.

In the present invention, when a fluorescent whitening agent is further contained in the transparent resin, the color tone is further stabilized by the combined effect with the above-mentioned white fine particles, and the original color tone is exhibited by various light sources. It is preferable in that a sheet for light source protection cover having a surprising effect can be obtained. The content of the fluorescent whitening agent is 0.001 to 0.1 with respect to 100 parts by weight of the transparent resin.
It is preferably in the range of parts by weight.

The structure of the sheet for light source protection cover of the present invention may be a single layer structure mainly composed of a transparent resin and containing the white fine particles therein, or the single layer sheet as a base material layer (A). A multilayer structure in which a surface layer (B) mainly composed of a transparent resin is formed on one side or both sides is also preferably applied. By forming the surface layer (B) mainly composed of a transparent resin, the color tone of the sheet can be finely adjusted, and the sheet surface has antistatic property, conductivity, water repellency, external light reflection property, It is preferable because it can impart all kinds of functions such as surface matting property, surface glossiness, surface curability, solvent resistance, and antifogging property. The layer mainly composed of the transparent resin containing the white fine particles, when used as a single layer, contains 6% of the transparent resin.
It is preferably contained in an amount of 0% or more, and when used as the base material layer (A), it is preferable to contain a transparent resin in an amount of 70% by weight or more. The surface layer (B) is made of transparent resin 60
It is preferable that the content is at least wt%. Further, the light source protective cover sheet of the present invention has a thickness of 0.
It is preferably 1 to 10 mm, more preferably 0.5 to 5 mm.

As the transparent resin for the surface layer (B), a methacrylic resin is preferably used because it has excellent surface texture and high-grade feeling when used for a light source protection cover and is excellent in processability. Further, the transparent resin of the base material layer (A) and the transparent resin of the surface layer (B) may be the same or different, but are preferably the same kind from the viewpoint of improving the adhesiveness between them.

In the multi-layered light source protective cover sheet of the present invention, the thicknesses of the base material layer (A) and the surface layer (B) are important.

That is, when the thickness of the entire sheet is 1, the thickness of the base material layer (A) is 0.1 to 1, more preferably 0.
Must be 5-1. When the ratio of the thickness of the base material layer (A) to the total sheet thickness is in the range of 0.5 to 1, the characteristics of the light source protection cover sheet are determined by the color tone and optical characteristics of the base material layer (A), It is preferable because a wide variety of light source protective cover sheets can be designed without being restricted by the structure.

The ratio t _A / t _B of the thickness t _B of the surface layer (B) to the thickness t _A of the base material layer (A) is 5-9.
It should be 0, more preferably 20 to 90. Surface layer (B) t _{B with} respect to thickness t _A of base material layer (A)
If the thickness ratio t _A / t _B of 20 is in the range of 20 to 90,
The surface layer (B) is preferable because it hardly affects the color tone and optical characteristics of the light source protection cover sheet.

The method for producing the sheet for light source protection cover of the present invention is preferably a method in which the white fine particles can be uniformly dispersed in the transparent resin, for example, a polymerizable monomer or a partially polymerized polymerizable monomer. As a raw material, at least one resin composition obtained by a method of dispersing the particles in a syrup for polymerization, or a method of mixing, melting, kneading and extruding the particles in a transparent resin that has been preliminarily polymerized. It can be obtained by various molding methods.

As an example of a method for obtaining a smooth sheet, a corrugated sheet and a prismatic sheet, an extrusion sheet forming method using a T die can be mentioned. The sheet can be subjected to secondary processing by a method such as vacuum forming, pressure forming, stampable forming, etc., and used as a light source protection cover.
Further, the light source protective cover sheet of the present invention can be obtained by a method such as profile extrusion molding, blow molding, injection molding, and compression molding using an annular die.

In order to obtain a multi-layered sheet, a coextrusion molding method in which two or more kinds of resin compositions are simultaneously melted and extruded,
A method of laminating one of the two types of resin compositions while extruding one of them in a single layer, a method of pressing and thermocompression bonding after preforming the two types of resin compositions, a method of continuously overlapping and bonding , Vacuum forming, laminating at the time of pressure forming, and the like.

The light source protective cover sheet of the present invention contains other components such as a reinforcing agent, a filler, a release agent, a heat stabilizer, and an antioxidant as long as the color tone, optical characteristics and other physical properties are not impaired. Agent, nucleating agent, light stabilizer, ultraviolet absorber,
All kinds of additives such as a plasticizer can be contained in any process for producing, such as during production of the sheet raw material or sheet forming process.

In the present invention, the chromaticity coordinates of transmitted light and reflected light using a standard light source defined by JIS Z-8720 can be measured with a commercially available measuring instrument according to the JIS Z-8722 method. Can be done using.

When the chromaticity coordinate of the transmitted light is measured using the three types of standard light sources defined by JIS Z-8720 in the sheet for light source protection cover manufactured as described above,
The relationship between the chromaticity coordinates (x _L , y _L ) of each standard light source and the chromaticity coordinates (x _T , y _T ) of transmitted light of the sheet is expressed by the following formula (I) and The present invention is achieved when (II) is simultaneously satisfied.

0.001 ≦ | x _L −x _T | ≦ 0.015 (I) 0.0005 ≦ | y _L −y _T | ≦ 0.02 (II) Further, in the above sheet, when measured chromaticity coordinates of the reflected light by using the standard light source three, the chromaticity coordinates (x _L, y _L) of each of the standard light source and the chromaticity coordinates of the reflected light of the sheet (x _R, y _The present invention is more preferably achieved when the relationship with _R ) simultaneously satisfies the following formulas (III) and (IV) in all standard standard light sources.

0.005 ≦ | x _L −x _R | ≦ 0.03 (III) 0.0005 ≦ | y _L −y _R | ≦ 0.035 (IV)

[0034]

The present invention will be described below in detail with reference to examples and comparative examples. The evaluation and test methods used in each of the examples and comparative examples are as follows.

(1) Observation of the shape of white fine particles: About 0.01 g of white fine particles was sampled, carbon was vapor-deposited, and a scanning electron microscope ("S-530" manufactured by Hitachi, Ltd.) was used to measure 30
Observe the shape at a magnification of 00 times.

(2) Measurement of particle size distribution of white fine particles: The white fine particles are ultrasonically dispersed in an aqueous surfactant solution,
Centrifugal automatic particle size distribution measuring device (“CAP manufactured by Horiba Ltd.
A-700 type ") is used to measure the particle size distribution by a light transmission type sedimentation particle size distribution measuring method. From the obtained particle size distribution,
The weight average particle size _Dd is determined.

(3) Measurement of chromaticity coordinates: JIS Z-87
According to the No. 22 method, “TC-1800” manufactured by Tokyo Denshoku Kogyo Co., Ltd.
Type "automatic color analyzer, the chromaticity coordinates x _L and y _{L of} the standard light source, the chromaticity coordinates x _T and y _T of the transmitted light of the sheet test piece, and the chromaticity coordinates x _R and y _{R of the} reflected light.
Is measured. The standard light source is evaluated by using three kinds of light sources of A light source, C light source, and D65 light source. In order to simply express the evaluation result, the absolute value of the difference in each chromaticity coordinate is Δx _T =
_{| X L -x T |, Δy} T = | y L -y T |, Δx R = |
It is shown as x _L −x _R |, Δy _R = | y _L −y _R |.

(4) Evaluation of color tone of fluorescent lamp: JIS C
The sheet test pieces were mounted on three types of fluorescent lamps for general lighting (light bulb color (L), neutral white (N), daylight color (D)) specified by -7601, and the color tone when the lamp was turned on and off was visually observed. Evaluate with. In the evaluation results, ◯ indicates a state in which the color tone of the fluorescent lamp is not impaired at both lighting and extinguishing, and x indicates a state in which the color tone changes at either lighting or extinguishing. If the color tone can be used for all three types of lamps without any problem, the judgment is ◎.

(5) Evaluation of light transmittance and light diffusion: JIS
-"100" manufactured by Nippon Denshoku Industries Co., Ltd. according to the K-7105 method.
The total light transmittance and haze of the test piece are measured using a "1-DP type" haze meter.

The materials used in the respective examples and comparative examples were those prepared as follows.

Preparation of White Fine Particles: The shapes of various white fine particles shown in Table 1 are confirmed by the method (1). In addition, classification is performed by a method that combines the sedimentation classification method that utilizes the difference in the sedimentation velocity of particles and the centrifugal classification method, and then the particle size distribution is measured by the method of (2) above, and the weight average particle diameter is calculated from the obtained distribution. Find the diameter. The results of the shape and the weight average particle diameter are shown in Table 1.

Preparation of sheet material for light source protection cover: Table 1
As shown in, a methacrylic resin (trade name "Delpowder 70H", manufactured by Asahi Kasei Kogyo Co., Ltd.), white fine particles, and other components are blended and homogeneously mixed using a tumbler, and then a vented extruder 30 mmφ twin-screw extruder At a resin temperature of 250
Melt kneading at ℃ to pelletize, and raw materials (A-1) to (A
-6) is obtained.

Similarly, as shown in Table 2, a methacrylic resin (trade name "Del Powder 70H", manufactured by Asahi Kasei Kogyo Co., Ltd.)
And other ingredients are mixed and mixed homogeneously using a tumbler, and then melt-kneaded into pellets by melting and kneading at a resin temperature of 250 ° C. with a vented extruder 30 mmφ twin-screw extruder.
1) to (B-3) are obtained.

Examples 1 and 2 As shown in Table 3, the first extruder (screw diameter 50 m
mφ, L / D = 32, uniaxial feed port for the base material layer (A), the second extruder (screw diameter 25 mm)
(φ, L / D = 32, uniaxial) feed material for the surface layer (B) is fed to the feed block die,
A three-layer sheet having a width of 280 mm was prepared by performing coextrusion sheet molding using a unit composed of three polishing rolls. The obtained sheet had a configuration in which the surface layer (B) was laminated on both surfaces of the base material layer (A). The thickness of each resin layer was adjusted by the discharge amount balance of two extruders. The overall thickness of the sheet is the clearance of the polishing roll.
The target was adjusted to 0 mm. Using the sheet as a test piece, the above evaluations (3) to (5) were performed. The results are shown in Tables 4 and 5.

The chromaticity difference between the standard light source and the transmitted light of the test piece was Δx _T = 0.001 to 0.015 in any light source.
Δy _{T was in} the range of 0.0005 to 0.02, which was very preferable. Further, the chromaticity difference of the reflected light is Δx _T = 0.005 to 0.03, Δy in any light source.
_{T was in} the range of 0.0005 to 0.03, which was preferable. In addition, the color tone was not impaired by using any of the three types of fluorescent lamps, and all the lamps could be used without any problems, so the evaluation was ⊚. Further, the total light transmittance was 53 to 55%, the haze was 93%, and the balance between the light transmittance and the light diffusibility was maintained, which was also preferable in this respect.

Examples 3 to 4 Example 1 was repeated except that only the first extruder was started.
In the same manner as in No. 2 to No. 2, single-layer sheets consisting only of the raw materials for the base material layer (A) shown in Table 3 were obtained. Using the sheet as a test piece, the above evaluations (3) to (5) were performed. The results are shown in Tables 4 and 5.

The chromaticity difference between the transmitted light between the standard light source and the test piece was Δx _T = 0.001 to 0.015, Δ
It was in the range of y _T = 0.0005 to 0.02, which was very preferable. Further, the chromaticity difference of reflected light is Δx _T = 0.005 to 0.03, Δy _T
It was in the range of 0.0005 to 0.03, which was preferable. In addition, the color tone was not impaired by using any of the three types of fluorescent lamps, and all the lamps could be used without any problems, so the evaluation was ⊚. Further, the total light transmittance is 54 to 58%, the haze is 93%, and the balance between the light transmittance and the light diffusivity is maintained, which is also preferable in this respect.

Comparative Examples 1 and 2 As shown in Table 3, the same procedure as in Examples 1 and 2 was repeated except that the raw materials for the base layer (A) and the raw material for the surface layer (B) were changed. A layered sheet was obtained. The obtained sheet showed a constitution in which the surface layer (B) was laminated on both surfaces of the base material layer (A). Using the sheet as a test piece, the above evaluations (3) to (5) were performed. The results are shown in Tables 4 and 5.

In Comparative Example 1, in the C light source and the D65 light source, the chromaticity difference Δx _T between the standard light source and the transmitted light of the test piece is 0.00.
It did not fall within the range of 1 to 0.015 and was not preferable. Further, when it was installed in a D-color fluorescent lamp, its color tone was impaired, and the judgment was x, which was not preferable.

In Comparative Example 2, the chromaticity difference Δx _T between the standard light source and the transmitted light of the test piece in the A light source and the D65 light source is 0.00.
It did not fall within the range of 1 to 0.015 and was not preferable. Further, when the fluorescent lamp was installed in the L-color fluorescent lamp and the D-color fluorescent lamp, the color tone was impaired, and the judgment was x, which was not preferable. Furthermore, the total light transmittance is as low as 44%, and the balance between light transmission and light diffusion is poor,
This point was not preferable either.

Comparative Examples 3 to 4 As shown in Table 3, the substrate layer (A) was prepared in the same manner as in Examples 3 to 4 except that the raw material for the substrate layer (A) was changed.
A single-layer sheet consisting of only raw materials was obtained. Using the sheet as a test piece, the above evaluations (3) to (5) were performed. The results are shown in Tables 4 and 5.

In Comparative Example 3, the chromaticity difference Δx _T between the standard light source and the transmitted light of the test piece in the C light source and the D65 light source is 0.00.
It did not fall within the range of 1 to 0.015 and was not preferable. Further, when the fluorescent lamps were installed on all three types, the color tone was impaired, and the judgment was x, which was not preferable. Further, the haze was as low as 89%, and the balance between the light transmission property and the light diffusion property was poor, which was not preferable also in this respect.

In Comparative Example 4, the chromaticity difference Δx _T between the standard light source and the transmitted light of the test piece in the A light source was 0.001 to 0.01.
It was not preferable because it did not fall within the range of 5. Also,
When it was installed in all three types of fluorescent lamps, the color tone was impaired, and the evaluation was x, which was not preferable. Furthermore, the total light transmittance was as high as 91%, and the balance between the light transmittance and the light diffusibility was poor, and this point was not preferable either.

[0054]

[Table 1]

[0055]

[Table 2]

[0056]

[Table 3]

[0057]

[Table 4]

[0058]

[Table 5]

[0059]

The color tone-retaining sheet for a light source protection cover of the present invention protects an exposed light source, effectively transmits and diffuses the light emitted by the light source, and does not impair the color tone of various light sources at the time of lighting. In addition, since the change in color tone due to the shadow of the light source does not occur when the light is turned off, it has an excellent appearance that can be commonly used for various light sources and is extremely useful.

Claims (5)

[Claims] 1. One or more types of white, which are mainly made of a transparent resin, do not melt at a molding temperature of the transparent resin, have a substantially cubic shape, and have a weight average particle diameter of 0.1 to 30 μm. Containing Fine Particles and JIS Z-8720
When the chromaticity coordinates of the transmitted light are measured using the standard light source specified in 1., all the measured values of each standard light source simultaneously satisfy the following formulas (I) and (II). Color retention sheet for protective cover. 0.001 ≦ | x _L −x _T | ≦ 0.015 (I) 0.0005 ≦ | y _L −y _T | ≦ 0.02 (II) (where x _L and y _L are standard Chromaticity coordinates of light source, x _T , y _T
Represents the chromaticity coordinate of the transmitted light of the sheet. ) 2. In the sheet according to claim 1, when the chromaticity coordinates of the reflected light are measured using a standard light source defined by JIS Z-8720, measurement with each standard light source is performed. A color tone retaining sheet for a light source protection cover, wherein all the values simultaneously satisfy the following formulas (III) and (IV). 0.005 ≦ | x _L −x _R | ≦ 0.03 (III) 0.0005 ≦ | y _L −y _R | ≦ 0.035 (IV) (where x _L and y _L are standard Chromaticity coordinates of light source, x _R , y _R
Represents the chromaticity coordinate of the reflected light of the sheet. ) 3. The color tone maintaining sheet for a light source protection cover according to claim 1, which contains 0.001 to 0.1 part by weight of a fluorescent whitening agent. 4. The sheet according to any one of claims 1 to 3 as a base material layer (A), and a surface layer (B) mainly composed of a transparent resin is provided on one surface or both surfaces thereof. Color retention sheet for light source protection cover. 5. The light source protection cover according to claim 1, wherein the transparent resin is a methacrylic resin.