JPH10202760A - Color tone sheet for light-source protecting cover - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve light transmission and light diffusing properties without impairing original color at lighting-up and at lighting-out by a method wherein this sheet contains a transparent resin and a rutile crystalline titanium dioxide and fine light diffusible particles, the weightaverage particle diameters of both of which are respectively specified, so as to specify the measured values of the chromaticity coordinates of transmitted lights of lights emitted from respective light sources. SOLUTION: A rutile-type titanium dioxide and fine light diffusible particles are added to a transparent resin. The weight average particle diameter of the rutile-type titanium dioxide lies within the range of 0.01-0.1μm, while that of the fine lightdiffusible particles lies within the range of 0.1-50μm. As the fine light diffusible particles, fine particles made of calcium carbonate, crystalline silica, crosslinked styrene-based polymer or the like is exampled. Under the condition that the chromaticity coordinates of transmitted lights are measured with three kinds of standard light source given in JIS-Z 8720, the relationships between the chromaticity coordinates (xL, yL) of respective light sources and the chromaticity coordinates (xT, yT) of the transmitted lights of the sheet are set to satisfy simultaneously with the formulae I and II for all the light sources.

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 a light source, and more particularly, to a light source of various color tones which does not impair the original color tone of the light source at the time of lighting and extinguishing, and has a light transmittance. The present invention relates to a light source protective cover sheet having excellent light diffusion properties.

[0002]

2. Description of the Related Art As an example of a light source protection cover which sufficiently transmits light from a light source and uniformly diffuses the light source to prevent the light source from being directly seen by an observer, a lighting cover for home and facilities is used. , Various displays, display signs, and the like. Conventionally, these members have been required to have a function of being able to be formed into an arbitrary shape and to have a function of transmitting and diffusing the light amount of a light source, and to disperse fine particles having different refractive indexes in a transparent resin. Investigations have been made on transmission high diffusivity materials.

[0003] For example, a resin composition in which an inorganic powder such as glass is dispersed in a methacrylic resin (JP-A-54-1552).
No. 44) or a resin plate in which a transparent resin contains a silicone resin having a specific structure and particle size (Japanese Patent Laid-Open No. 1-172).
No. 801).

[0004]

The light diffusing resin disclosed in these prior arts maximizes the light of the light source as a light source protection cover, and has a uniform brightness without illuminating the image of the light source. The purpose is to obtain a surface having a color, and no study has been made on the color tone as a light source protective cover material. In other words, the color tone of the material in the above-described conventional technology is so-called milky white, but when used as a light source cover,
When the light source is turned on, the original color tone of the light source is changed, and when the light source is turned off, the shadow of the internal light source is projected and the image looks dark.

[0005] In recent years, the use of low-power, high-brightness type light sources has been promoted for the effective use of energy, but at the same time, attention has been paid to means for creating a comfortable space.
It is positioned as a product that enriches the living environment, such as harmony with indoor interiors, directing in gallery facilities and stores, and improving the scenery by lighting up buildings. In particular, there is a great need for illumination with high performance, and a variety of light sources having various color tones are presented, and a light source protective cover material that does not impair the color tone of these light sources is required.

The present invention relates to a cover sheet for protecting an exposed light source. More specifically, the present invention does not impair the original color tone of the light source when the light source is turned on and off in various color tones, and has light transmittance and light diffusion. An object of the present invention is to provide a sheet for a light source protective cover having excellent performance.

[0007]

The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems. As a result, at least transparent resin and rutile crystalline titanium oxide having a weight-average particle size in a specific range, and a weight-average particle size having a specific range. In a sheet having one or more layers including a base layer formed in combination with the light diffusing fine particles described in (1), three types of standard light sources (A, C, D65) specified in JIS-Z8720 are used. There is a specific relationship between the chromaticity coordinates of the transmitted light measured using it, and the light source protective cover sheet that is excellent in light transmittance and light diffusion without deteriorating the original color tone of the light source only when the relationship is met. Have been obtained, and the present invention has been achieved.

That is, the present invention provides at least a transparent resin, rutile crystalline titanium oxide having a weight average particle size in the range of 0.01 to 0.1 μm, and a weight average particle size of 0.1 to 50 μm.
m of one or more kinds of light diffusing fine particles in the range of m
When the chromaticity coordinates of the transmitted light are measured using a standard light source defined by JIS-Z8720, all the measured values at each light source satisfy the following expressions (1) and (2) at the same time. It is a color sheet for a light source protection cover.

(1) 0.001 ≦ | x _L −x _T | ≦ 0.0
15 (2) 0.0005 ≦ | y _L −y _T | ≦ 0.02 (where x _L and y _L are chromaticity coordinates of the standard light source, x _T and y _T
Indicates the chromaticity coordinates of the light transmitted through the sheet. )

It is preferable that rutile crystalline titanium oxide be contained in an amount of 0.005 to 0.1 part by weight and light diffusing fine particles in an amount of 0.1 to 30 parts by weight based on 100 parts by weight of the transparent resin.

In the above invention, the chromaticity coordinates of the reflected light are measured using a standard light source defined by JIS-Z8720 by appropriately setting the kind and amount of the rutile crystalline titanium oxide and the light diffusing fine particles. In this case, it is more preferable that all the measured values of the light sources satisfy the following expressions (3) and (4) at the same time.

(3) 0.005 ≦ | x _L −x _R | ≦ 0.0
3 (4) 0.0005 ≦ | y _L −y _R | ≦ 0.035 (where x _L and y _L are chromaticity coordinates of the standard light source, x _R and y _R
Indicates the chromaticity coordinates of the reflected light from the sheet. )

In the present invention, the transparent resin 100
A known optical brightener is used in an amount of 0.001 to 0.1 based on parts by weight.
It is preferably applied to contain by weight.

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

Further, a configuration in which the sheet according to the present invention is used as a base material layer (A) and a surface layer (B) mainly composed of a transparent resin is provided on one or both surfaces thereof is also preferably applied.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The transparent resin used in the present invention has a haze of 1 measured according to JIS K-7105.
It is defined as a substance that is 0% or less. Specific examples include methacrylic resin, polycarbonate resin, polystyrene resin, and styrene-methyl methacrylate copolymer resin. Particularly preferred is a methacrylic resin.

Examples of the methacrylic resin usable in the present invention include resins mainly composed of methyl methacrylate, such as a homopolymer of methyl methacrylate, or methyl methacrylate and methyl acrylate, ethyl acrylate,
Butyl acrylate, acrylonitrile, acrylic acid,
It includes a copolymer with any one or more of copolymerizable monomers such as methacrylic acid, 2-hydroxyacrylate, maleic anhydride, styrene, and α-methylstyrene. These may be used alone or may be blended.

In order to maintain transparency and provide impact resistance at the same time, an impact-resistant methacrylic resin containing a methacrylic rubber elastic material is used. The methacrylic rubber elastic material is disclosed in Japanese Patent Application Laid-Open No. 53-55854. JP, 55-949
No. 17, JP-A-61-32346, and the like. 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 a methacrylic polymer core material.

The weight average particle size used in the present invention is 0.0
Rutile crystalline titanium oxide in the range of 1 to 0.1 μm has a small difference in color tone between transmitted light and reflected light when dispersed in a transparent resin, and the light source's original color tone is exhibited by various light sources. It is very preferable in that a sheet for a light source protective cover having a surprising effect can be obtained.

When the weight average particle diameter of the light diffusing fine particles used in combination is in the range of 0.1 to 50 μm, refraction and reflection of visible light at the interface of each particle in the transparent resin effectively occur, and light transmittance is increased. This is preferable in that a sheet for a light source protective cover having excellent light diffusion properties can be obtained.

The particle size distribution of the rutile crystalline titanium oxide and the light diffusing fine particles used in the present invention is measured by a known light transmission type sedimentation particle size distribution measuring method or the like, and the weight average particle size is determined from the obtained distribution. Can do things. If the weight average particle size does not fall within the desired range, the particles can be classified and used within the above range.

Specific examples of the light diffusing fine particles used in the present invention include calcium carbonate, calcium fluoride, potassium fluoride, barium sulfate, magnesium sulfate, titanium oxide, potassium titanate, aluminum hydroxide, magnesium hydroxide, Inorganic substance particles such as crystalline silica, amorphous silica, glass flake, glass fiber, alumina, mica, talc, clay, etc .; crosslinked styrene polymer, crosslinked methacrylic polymer, crosslinked styrene-methacrylic copolymer, crosslinked Organic compound particles such as siloxane-based polymers may be mentioned, and these may be used alone or in combination of two or more.

The rutile crystalline titanium oxide used in the present invention is used in an amount of from 0.005 to 0.5% based on 100 parts by weight of the transparent resin.
1 part by weight of the light diffusing fine particles has a total content of at least one kind of light diffusing fine particles of 100 parts by weight of the transparent resin.
It is 1 to 30 parts by weight, more preferably 1 to 20 parts by weight. In this range, the color tone can be adjusted without extremely lowering the optical characteristics when dispersed in the transparent resin, particularly the total light transmittance, and a preferable light source protective cover sheet can be obtained.

In the present invention, when a known fluorescent whitening agent is contained in a transparent resin, the above rutile crystalline titanium oxide and light diffusing fine particles (hereinafter referred to as "white fine particles").
It is recommended because the color tone is further stabilized by the combined effect with and the original color tone is exhibited by various light sources. The content of the fluorescent whitening agent is 0.001 to 100 parts by weight of the transparent resin.
It is preferably in the range of 0.1 parts by weight.

Further, 0.000 of a known bluing agent is added.
It is possible to arbitrarily adjust the color tone by adding 005 to 0.00005 parts by weight.

The structure of the light source protective cover sheet according to the present invention may be a single layer structure composed of a transparent resin, the above-mentioned rutile crystalline titanium oxide, and light diffusing fine particles, or the single layer sheet may be formed of a base material layer ( As A), a multilayer structure having a surface layer (B) made of a transparent resin on one or both sides thereof is also preferably applied. The surface layer (B) made of a transparent resin allows the color tone of the sheet to be finely adjusted, and the surface layer (B)
Antistatic properties, surface matting properties, surface gloss, solvent resistance,
Providing a function such as anti-fogging property is preferable in that the function can be enhanced without significantly changing the original physical performance of the sheet.

As the transparent resin for the surface layer (B), a methacrylic resin is preferably used because it is excellent in surface texture and luxury when used for a light source protective cover and excellent in workability.

The ratio of the thickness of the base material layer (A) to the thickness of the surface layer (B) is such that when the thickness of the entire sheet is 1, the thickness of the base material layer (A) is preferably 0.5 or more. 0.7 or more is more preferable. Base material layer (A) with respect to total sheet thickness
When the thickness ratio is within this range, the characteristics of the light source protective cover sheet are determined by the color tone and the optical characteristics of the base material layer (A), and a wide variety of light source protective cover sheet designs can be made regardless of the layer structure. Becomes possible.

The thickness of the light source protective cover sheet is 0.1 to
The range of 5 mm is preferable, and if it is less than 0.1 mm, the strength of the sheet is low, and if it exceeds 5 mm, the weight becomes large and mounting becomes difficult.

The method for producing the light source protective cover sheet of the present invention is preferably a method in which rutile crystalline titanium oxide and light diffusing fine particles are uniformly dispersed in a transparent resin. The particles can be obtained by a method of dispersing the particles in a syrup of the polymerizable monomer thus polymerized, or a method of mixing, melt-kneading and extruding the particles in a transparent resin which has been polymerized in advance, or the like.

In order to obtain a smooth, corrugated, prism-shaped sheet or the like, a typical example is an extrusion sheet molding method using a T-die.

The sheet can be subjected to secondary processing by a method such as vacuum forming or pressure forming, and can be used as a light source protective cover.

Further, the sheet for the light source protective cover can be obtained also by a method such as profile extrusion molding by a profile die, blow molding, injection molding, compression molding and the like.

In order to obtain a multilayered sheet, a coextrusion molding method in which two or more 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 filler, a matting agent, a release agent, a heat stabilizer, and the like, as long as the color tone, optical properties, and other physical properties are not impaired. Additives such as antioxidants, light stabilizers, ultraviolet absorbers, and plasticizers can be included in any process, such as during the production of sheet raw materials or during sheet molding.

In the present invention, the measurement of the chromaticity coordinates of the transmitted light and the reflected light using the standard light source specified in JIS-Z8720 is performed using a commercially available measuring instrument according to the JIS Z-8722 method. Can do it.

When the chromaticity coordinates of the transmitted light are measured using three types of standard light sources specified in JIS-Z8720, the chromaticity coordinates (x _L , y _L ) of each light source and the color of the transmitted light of the sheet are measured. The present invention is achieved when the relationship with the degree coordinates (x _T , y _T ) satisfies the following expressions (1) and (2) simultaneously for all light sources.

(1) 0.001 ≦ | x _L −x _T | ≦ 0.0
15 (2) 0.0005 ≦ | y _L −y _T | ≦ 0.02

Further, when the chromaticity coordinates of the reflected light are measured using the above three types of standard light sources, the chromaticity coordinates (x
_L , y _L ) and the chromaticity coordinates (x _R , y _R ) of the reflected light of the sheet satisfy the following expressions (3) and (4) simultaneously for all the light sources. The present invention is achieved.

(3) 0.005 ≦ | x _L −x _R | ≦ 0.0
3 (4) 0.0005 ≦ | y _L −y _R | ≦ 0.035

[0041]

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) Measurement of Particle Size Distribution of Rutile Crystalline Titanium Oxide and Light-Diffusing Fine Particles White fine particles are dispersed in an aqueous surfactant solution by ultrasonic waves, and a centrifugal automatic particle size distribution analyzer (HORIBA, Ltd.) Made CA
(PA-700 type), and the particle size distribution is measured by a light transmission sedimentation particle size distribution measuring method. From the obtained particle size distribution,
The weight average particle size _Dd is determined.

(2) Measurement of chromaticity coordinates According to JIS Z-8722 method, T
Using C-1800 type automatic color analyzer, the standard light source chromaticity coordinates x _L, y _L and the chromaticity coordinates x _T of the transmitted light of the sheet specimen, y _T, and the chromaticity coordinates x _R of the reflected light, to measure the y _R. A light source, C light source, D light source
The evaluation is performed using three types of 65 light sources. In order to simply express the evaluation result, the absolute values of the differences between the chromaticity coordinates are represented by Δx _T = | x _L −x _T |, Δy _T = | y _L −y _T |, Δx _R =
_{| X L -x R |, Δy} R = | shown as | y _L -y _R.

(3) Evaluation of Color Tone of Fluorescent Lamp Three types of fluorescent lamps for general illumination specified by JIS C-7601 (bulb color (L), day white (N), daylight color (D))
A sheet test piece is mounted on the test piece, and the color tone when the lamp is turned on and off is visually evaluated. In the evaluation results, the mark “○” indicates a state in which the color tone of the fluorescent lamp is not impaired in both lighting and extinguishing, and the mark “x” indicates a state in which the color tone of the fluorescent lamp changes in either the lighting or extinguishing. If the color tone can be used for all three types of lamps without any problem, the judgment is ◎.

(4) Evaluation of Light Transmittance and Light Diffusivity According to JIS K-7105 method, Nippon Denshoku Industries Co., Ltd.
The total light transmittance and haze of the test piece are measured using a 001-DP haze meter.

Table 1 shows the adjustment of the sheet material for the light source protective cover.
As shown in, a methacrylic resin (trade name: Del Powder 70H, manufactured by Asahi Kasei Kogyo Co., Ltd.), light diffusing fine particles, and other components are blended, uniformly mixed using a tumbler, and a vented extruder 30 mmφ biaxial. Extruder resin temperature 2
Melt kneading at 50 ° C. to form pellets, sheet materials A1 to A1
A5 is obtained.

[0047]

[Table 1]

Among the light diffusing fine particles used in Table 1, the titanium oxide is ultrafine titanium oxide TTO-55S (trade name, manufactured by Ishihara Sangyo Co., Ltd.).

MBS is a cross-linked copolymer of methyl methacrylate-butyl acrylate-styrene, which is used in combination with MODIPER R200 (trade name: 20 μm) and R230 (particle size) manufactured by NOF Corporation. 40
.mu.m), charcoal-1 is heavy calcium carbonate, trade name ACE35 manufactured by Dowa Mining Co., Ltd. Charcoal-2 is heavy calcium carbonate and trade name ACE25, manufactured by the same company.
Char-3 charcoal is light calcium carbonate, trade name Sipron A manufactured by Shiraishi Calcium Co., Ltd.

Barium sulfate refers to AD sedimentable barium sulfate manufactured by Nippon Chemical Industry Co., Ltd.

The fluorescent whitening agent of the other component is Whiteflow HCS (trade name, manufactured by Sumitomo Chemical Co., Ltd.).

The particle diameters shown in the table are weight average particle diameters.

Similarly, as shown in Table 2, methacrylic resin (trade name: Del Powder 70H, Asahi Kasei Corporation)
) And other components are mixed, homogeneously mixed using a tumbler, melt-kneaded at a resin temperature of 250 ° C. with a vented extruder 30 mmφ twin-screw extruder, and pelletized to obtain a raw material B1.
To B2.

[0054]

[Table 2]

In the other components of Table 2, talc powder is NTX-A174 (trade name, manufactured by Nippon Talc Co., Ltd.), silicone-based crosslinked beads are Tospearl 120 (trade name, manufactured by Toshiba Silicone Co., Ltd.), and fluorescent brightening. Table 1 shows the white flow HCS manufactured by Sumitomo Chemical Co., Ltd.

(Example 1) Sheet raw material A1 shown in Table 1
Using an extruder (screw diameter 50 mmφ, L / D = 3
2, a single axis), a sheet die, and three polishing rolls are used to form a sheet having a width of 280 mm.

The thickness of the sheet is set to 2 mm by adjusting the extrusion amount of the extruder, the sheet take-up speed, and the clearance of the polishing roll.

Example 2 A sheet is prepared in the same manner as in Example 1 except that A2 is used as a sheet material.

(Examples 3 and 4) The extruder of the sheet forming unit used in Example 1 was used as a first extruder, and a second extruder (screw diameter 25 mmφ, L / D = 32, single screw) was used. And a feed block, and form a two-type three-layer sheet by a co-extrusion method.

In the first extruder, sheet material A was used as a base material layer.
1, and the sheet material B1 was used as a surface layer in the second extruder.
(Example 3) and B2 (Example 4) are used.

The obtained sheet has a structure in which a surface layer is laminated on both sides of a base material layer, and the thickness of each layer is adjusted by a balance between the extrusion amounts of the first and second extruders.

Thus, a sheet having a surface layer of 30 μm each and a total thickness of 2 mm is obtained.

(Comparative Examples 1 and 2) A3
Example 1 except that (Comparative Example 1) and A4 (Comparative Example 2) were used.
Create a sheet in the same way as.

(Comparative Example 3) A5, B2
A sheet is created in the same manner as in the third embodiment except that.

Table 3 shows combinations of sheet materials used in Examples and Comparative Examples, and Table 4 shows differences between chromaticity coordinates of the standard light source and the obtained sheets.

[0066]

[Table 3]

[0067]

[Table 4]

Table 5 summarizes the evaluation results of the sheets obtained as described above.

[0069]

[Table 5]

In the sheets of Examples 1 to 4, the chromaticity difference between the standard light source and the transmitted light of the test piece was Δx _T =
0.001 to 0.015, Δy _T = 0.0005 to 0.5.
02. In addition, the chromaticity difference of the reflected light was Δx _R = 0.005 to 0.03 and Δy _R =
It is preferably in the range of 0.0005 to 0.035. The judgment is 何 れ because the color tone is not impaired even if any of the three fluorescent lamps is used, and the lamp can be used without any problem. Further, the total light transmittance is preferably 50 to 51%, and the haze is preferably 91 to 93%, since the balance between light transmittance and light diffusion is maintained.

In Comparative Example 1, the chromaticity difference Δx _T between the standard light source and the transmitted light of the test piece was 0.001 to 0.01 in the A light source.
5 is out of the range. Further, in reflected light, C and D
At 65 light sources, Δx _R is not preferable because it does not fall within the range specified in the present invention. In addition, when the lamps are installed in the L and D color fluorescent lamps, the color tone is impaired in both cases, so that the judgment is unfavorable as x.

In Comparative Example 2, the chromaticity difference Δy _T between the standard light source and the transmitted light of the test piece was 0.0005 to 0.0 in the A light source.
2 is outside the range. Furthermore, in reflected light, A, C, D
It is not preferable that Δy _R at 65 light sources and Δx _R at A light source do not fall within the range specified in the present invention. In addition, when the lamps are installed in the L, N, and D color fluorescent lamps, the color tone is impaired. Furthermore, the total light transmittance is 9
It is as high as 1%, which is not preferable because the balance between light transmittance and light diffusion is poor.

In Comparative Example 3, the chromaticity difference Δx _T between the standard light source and the transmitted light of the test piece was 0.001 to 0.01 in the A light source.
5 is out of the range. Further, the chromaticity difference Δx _R of the reflected light is not preferable because it does not fall within the range specified in the present invention. In addition, when the lamp is installed in an L-color fluorescent lamp, the color tone is impaired, and the determination is unfavorable because the judgment is x.

[0074]

The light source protection cover obtained by the present invention protects an exposed light source, effectively transmits and diffuses light emitted from the light source, and does not impair the color tone of various light sources when turned on and off. This is extremely useful because it can be used in common for various light sources.

Claims (6)

[Claims] 1. At least a transparent resin, rutile crystalline titanium oxide having a weight average particle size in a range of 0.01 to 0.1 μm, and at least one kind having a weight average particle size in a range of 0.1 to 50 μm. JIS-
When the chromaticity coordinates of transmitted light are measured using a standard light source specified by Z8720, all measured values of each light source satisfy the following expressions (1) and (2) at the same time. Tone sheet for cover. (1) 0.001 ≦ | x _L −x _T | ≦ 0.015 (2) 0.0005 ≦ | y _L −y _T | ≦ 0.02 (where x _L and y _L are chromaticities of a standard light source) coordinates, x _T, y _T represents the chromaticity coordinates of transmitted light of the sheet.) 2. The composition according to claim 1, wherein the content of rutile crystalline titanium oxide is 0.005 to 0.1 parts by weight and the light diffusing fine particles are 0.1 to 30 parts by weight based on 100 parts by weight of the transparent resin. 2. The color sheet for a light source protective cover according to 1. 3. When the chromaticity coordinates of reflected light are measured using a standard light source specified in JIS-Z8720, all measured values of each light source satisfy the following expressions (3) and (4) at the same time. The color tone sheet for a light source protection cover according to claim 1 or 2, wherein: (3) 0.005 ≦ | x _L −x _R | ≦ 0.03 (4) 0.0005 ≦ | y _L −y _R | ≦ 0.035 (where x _L and y _L are chromaticities of the standard light source) coordinates, x _R, y _R represents a chromaticity coordinates of the reflected light of the sheet.) 4. The color tone sheet for a light source protective cover according to claim 1, wherein 0.001 to 0.1 part by weight of a fluorescent whitening agent is contained based on 100 parts by weight of the transparent resin. 5. The color sheet for a light source protective cover according to claim 1, wherein the transparent resin is a methacrylic resin. 6. A light source protective cover, wherein the sheet according to claim 1 is used as a base layer (A), and a surface layer (B) made of a transparent resin is provided on one or both sides thereof. Color sheet.