JP2018133321A - Method for producing high color rendering cover for led illumination - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide am illumination cover that improves the color rendering properties of a light source of a straight-tube LED illumination using a white LED element and prevents the deterioration of illuminance.SOLUTION: The material resin of an illumination cover is limited to polycarbonate resin (refractive index 1.58). In an organic transparent coating agent (organic transparent resin+dilution solvent) with a lower refractive index than that of the resin, dispersed is a trace amount of metal complex salt dye, to coat (dip and dry) its inner surface and outer surface.SELECTED DRAWING: Figure 3

Description

The present invention relates to an improvement in the optical performance of an illumination cover used for light emitting diode (hereinafter referred to as LED) illumination, more specifically, an illumination device having a white LED element that emits emitted light through an illumination cover made of polycarbonate resin. The present invention relates to a high color rendering cover for LED lighting that can increase the average color rendering index: Ra and the special color rendering index: R9 to R15.
The white LED element is a light emitting body including a blue light emitting diode light source and a yellow phosphor in a fluorescent portion.

LED lighting is used in various lighting spaces due to its low power consumption and long life performance, and low power consumption and long life are completely established. Furthermore, in various spaces, the role of lighting for a comfortable living environment and a safe and efficient work environment is increasing.
However, as an illumination light source, color rendering properties when illuminating an object may be a problem, and in recent years, many techniques for improving and optimizing color rendering properties have been proposed for LED elements.

However, regarding LED lighting covers through which light emitted from LED elements is transmitted and diffused, there are few proposals for improving the color rendering properties as LED elements.
This background has a technical problem that the brightness (illuminance) decreases when a high color rendering process is performed on a plastic cover such as polycarbonate resin or polymethyl methacrylate resin used as a cover for LED lighting.
In other words, high color rendering and brightness (illuminance: Lux) are in a trade-off relationship, and securing high color rendering and increasing illuminance has a limit in cover materials using a white LED illumination light source.

LED lighting is roughly divided into a bulb type, a straight tube type (fluorescent tube type), and others.
In either method, a plastic diffusion cover is used, but polycarbonate resin is most frequently used in terms of optical performance, safety durability, and cost.

Lighting applications that require high color rendering are extremely wide-ranging, and are necessary for precision processing and inspection processes, not to mention printing, painting, and design rooms.
Currently, a three-wavelength fluorescent tube is mainly used, and there is a great need for a straight tube type LED illumination that can replace the fluorescent tube as it is, and the color rendering property of the straight tube type LED lighting cover is extremely important.
In recent years, the need for alternatives to LED lighting with excellent power consumption and longevity is rapidly increasing, and among them, the demand for high color rendering straight tube type LED lighting using inexpensive white LED elements is increasing.

Conventional technology

Patent Document 1 describes a method for improving color rendering by coloring a lighting cover.
It is described that the color rendering can be improved by softening the illumination of the fluorescent lamp illumination cover. ("0040")

Further, it is described that the surface light emitting portion (light guide plate) is formed of a transparent and translucent polymer resin, and the color rendering property of the lighting fixture can be improved by coloring the polymer resin. (“0045”)

However, there is no description about the effect of improving the color rendering property when the lighting is turned on by measuring the color rendering property evaluation number when the light guide plate is used.
Furthermore, no mention of illuminance and measurement results are given.

Patent Document 2 describes improvement in color rendering properties of a straight tube type LED lighting cover.
It is described that a light transmission diffusion filter is used as a cover, quartz glass fine particles, a light diffusion material, and a dye such as red are uniformly dispersed in the filter, and a phosphor is attached as a color rendering property improving agent.

When LED white light is irradiated on the outer surface of the silica glass fine particles, the light is reflected and transmitted through the surface of the silica glass fine particles, and the phosphor on the surface of the fine particles excites and emits light, thereby producing a red color rendering. In addition, an apparent red light bulb color light can be obtained with a colorant such as a red dye, and by combining with a green colorant, an expensive three-wavelength LED is not used, and color rendering is improved. It is stated that it can be done. ("0017")

In addition, it is stated that direct dyes or pigments may be used as various dyes of the color rendering property improving material, and selection of the type of dye for long-term light durability (light fastness) when used for LED lighting covers Is not mentioned.
(“0035”)

There are several patent documents in which the color rendering index (R1 to R15) and the average color rendering index (Ra) are described.
However, these are lighting devices in which the LED element has a plurality of wavelength systems or the fluorescent part has a plurality of phosphors, and there is no description for enhancing the color rendering properties of the lighting cover.

Patent Document 3 discloses a blue light emission, blue green light emission, orange light emission, and red light emission LED illumination light source, and an appropriate range in which high color rendering can be exhibited with respect to the range of correlated color temperature, the order of the peak emission intensity of each color, and the wavelength range. Is heading.
The measured values of the color rendering index by the 4-wavelength LED element are Ra = 94, R9 to R15 = 70 to 98 at a relative color temperature of 3000K, and Ra = 96, R9 to R15 = 80 to 98 at a relative color temperature of 5000K. It is.

Patent Document 3 describes a preferable range of peak wavelengths of LED light sources for blue light emission, blue-green light emission, orange light emission, and red light emission from the viewpoint of increasing Ra, and the range has a correlated color temperature of less than 5000K. It is described that there is no change even in the case of 5,000 K or more.
The illumination device is a beam light type in which 60 LED elements are arranged on a square surface, and there is no description about a straight tube type instead of a fluorescent lamp.

Patent Document 4 describes a bullet-type LED illumination device composed of two types of blue LED elements having different peak wavelengths and a plurality of phosphors. It is described that the emitted light is white (color coordinates x = 0.372, y = 0.378), and the measured values of the color rendering index are Ra = 96, R9 to R15 = 80 to 98. (“0056”)
From the measured values of the color coordinates, the color temperature corresponds to approximately 4000K.

White fluorescent lamps widely used for indoor lighting are classified into three levels: correlated color temperature 3500K (warm white), 4200K (white) 5000K (lunch white), and white LED lighting also has a correlated color temperature 4200K of white. Can be applied.

Therefore, in the prior art, the range of the color rendering index in which the white LED illumination in the vicinity of the correlated color temperature of 4000 K to 4500 K is high color rendering is Ra is 95 or more, and R9 to R15 is 80 to 98.
However, the high color rendering index is not achieved by the color rendering property improving technique related to the lighting cover, but is a lighting device having a plurality of LED elements or a plurality of phosphors.

Regarding the special color rendering index (R9 to R15), 6 color renderings out of 7 color renderings are good numerical values with an evaluation number of 95 or more, but the evaluation numerical value for 1 color rendering is around 80.

Prior patent documents

Japanese Patent No. 5339405 Japanese Patent No. 4379750 Japanese Patent No. 3940750 Japanese Patent No. 4989936

The present invention relates to an illuminating device having a straight tube type white light emitting diode element (LED element) having a correlated color temperature of 4000 to 4500 K, and relates to an invention of high color rendering technology of the illumination cover. The range of the color rendering index is in the range of Ra of 95 or more and R9 to R15 of 80 to 98.
However, there is a technical problem that brightness (illuminance) decreases when high color rendering is performed on a plastic cover. The present invention solves this technical problem by imparting high color rendering properties without sacrificing brightness (illuminance).

In the present invention, as a result of studying earnestly in order to solve the above problems, the lighting cover is limited to polycarbonate resin (refractive index 1.58), and an organic transparent coating agent (organic transparent resin) having a lower refractive index than the resin. The above problem can be solved by dispersing a small amount of a metal complex dye in the (diluting solvent) and coating (dipping and drying).

An organic transparent resin having a refractive index of less than 1.5 has been proposed as a low refractive index agent capable of being coated with an organic solvent as a solvent for plastic.
Inorganic particles such as silica, organic fine particles with low refractive index such as styrene and acrylic resin have been proposed as low refractive index antireflection materials, and can be selected as an organic transparent coating agent by blending an easily adhesive binder with polycarbonate resin .

The polycarbonate resin is preferably a type in which a light diffusing agent and an ultraviolet absorber are kneaded, and a grade capable of melt extrusion molding is preferred.
Furthermore, it is preferable that the color is white, the diffused light transmittance is 60% or more, and the long-term heat resistance (UL-746B) RIT (RTI = relative thermal index) is 125 ° C. or more.

The organic transparent coating film is required to have a low refractive index relative to the polycarbonate resin having a refractive index of 1.58, but the refractive index is preferably in the range of 1.4 to 1.5.
It is known that a larger refractive index difference is more effective for suppressing reflection at the interface between the laminated film and the polycarbonate resin. However, if the refractive index is too large, the variation in reflectance with respect to wavelengths in the visible light region increases. The refractive index of the organic transparent coating film is more preferably in the range of 1.45 to 1.5.

The film thickness of the organic transparent coating film is preferably 100 nm to 1000 nm (nanometers) within a range that does not affect the adhesion and brightness (illuminance), but taking into account precise film thickness control and organic solvent cost reduction, More preferably, the range of 150 nm to 400 nm is desirable.

The present invention has found that a metal complex dye is provided as a dye that imparts an effect of increasing the illuminance of the lighting cover by the coating, can be uniformly dispersed in the coating liquid, does not easily precipitate, and has excellent light fastness.
Metal complex dyes have excellent light fastness, no sublimation and bleeding, many colors, and good dispersibility in organic transparent coating agents.
Select one that has low solubility in the coating diluent, disperse it in an organic transparent coating agent, and coat (dip and dry) the polycarbonate resin cover.

The metal complex dye is preferably a 1: 2 type metal complex dye in which two dye molecules are bonded to one metal atom.
When the organic transparent resin and the metal complex dye are uniformly dispersed in the diluting solvent, the color changes slightly.
The amount of the dye added to the organic transparent resin is preferably less than 0.2% by weight.
If this level is exceeded, the brightness (illuminance) decreases and the color rendering evaluation value also decreases.
However, if it is less than 0.1%, the effect of improving the color rendering index is hardly exhibited, and if it is 0.2% or more, the illuminance decreases.
Therefore, a high color rendering LED lighting cover can be obtained by adding and coloring the metal complex dye in the range of 0.1% to 0.2% by weight with respect to the resin solid content.

In the white LED lighting device, since the intensity of the blue light emitting component emitted by the white LE element remains strong at the peak of the wavelength of the light emitted from the diffusion cover, the color of the dye is yellow or orange, which are complementary colors of blue. Is desirable.
In the present invention, it has been found that lemon-colored yellow to orange-based yellow are suitable.

Although the object of the present invention is a straight tube type LED lighting cover, it is also effective for a flat plate type LED lighting cover for base light, and the arrangement of the LED lighting module is either a direct type or an edge light type. Also effective.

The straight tube type LED illumination cover according to the present invention has a simple structure and can enhance the color rendering of excellent white LED emitted light.
That is, as an effect of the present invention, the technical means can improve the color rendering property of the light emitted from the illumination cover of the white LED light, and can further improve the brightness (illuminance) by several percent.

Hereinafter, the present invention will be described more specifically with reference to examples. The present invention is not limited thereby.
As shown in FIG. 1, the cylindrical wall thickness 1mm in a mold with an outer diameter of 26mmφ dimension light diffusing polycarbonate resin (Teijin Ltd. ^{ML-6105ZHP MVR = 2.5cm 3 /} 10min.) At melt extrusion The mold cover 1 was continuously extruded to create five straight pipe covers having a length of 1 m, and designated as No. 1 to No. 5.
Number 1 was a blank white cover without coating. (Number 1)

A product name PC301 (an organic coating agent having a refractive index of 1.47) manufactured by Colcoat Co., Ltd. was diluted in isopropyl alcohol: normal butanol = 1: 1 to obtain a solid content ratio of 3.8%. A straight pipe cover was dip-coated on both the inside and outside of the bath filled with this coating solution. It dried at 120 degreeC x 1 minute, and laminated | stacked the organic resin transparent film on the inner and outer surface of a straight pipe cover. (Number 2)
The color of the product cover was the same white color as the blank cover.

The white LED module 3 is inserted into the polycarbonate resin cover 1 by inserting the aluminum frame 4 (# 6063 pure Al content: 99.35%) into the slide claw 2 and fixing the white LED module tape to the flat surface of the frame with glue. . As the LED module tape, a commercially available product having a substrate width of 9 mm, SMD type 3528 LED: white color 120 chips / meter 12 volts, power consumption 9.6 watts was used.

The white LED was turned on in a dark room where light from the external environment could be ignored, and an illuminance meter was placed at a vertical distance of 20 cm from the straight tube cover, and the illuminance (Lx) was measured at 10 points to obtain an average value.
Furthermore, the color rendering index R (i), i = 1 to 15 was measured with the color rendering property measuring instrument at the same position.
The average color rendering index Ra = (ΣR (i) i = 1-8) / 8.

Table 1 shows the correlated color temperature, the color rendering index, and the illuminance when the white LED is turned on for the white blank cover and the cover on which the organic transparent coating is applied to the blank cover.

As a result, the blank white cover (No. 1) and the coating cover (No. 2) showed no difference in the evaluation numbers of correlated color temperature and color rendering, and the illuminance of No. 2 increased by about 5%.
Further, the results of changing the color and addition amount of the metal complex dye are described in Example 1, Example 2, and Comparative Example 1.

To the coating solution having a solid content ratio of 3.8%, a metal complex salt dye Eisenspiron Yellow GRLH Special manufactured by Hodogaya Chemical Industry Co., Ltd. was added at a solid content weight ratio of 0.1%, and the mixture was stirred and dispersed. The inner and outer surfaces of the straight pipe cover were applied by dip (immersion) to the filled bath.
It dried at 120 degreeC x 1 minute, and laminated | stacked the transparent film on the inner and outer surface of a straight pipe cover. (Number 3)
The color of the product cover was light yellow.

As a result, the illuminance was hardly changed as compared with No. 2, and the color rendering index was Ra = 98, R9 to R15 = 82 to 100.
By using a yellow complementary color as the dye, the illuminance of the white LED straight tube illumination is not reduced and the color rendering is improved. In Table 1, the correlated color temperature, the color rendering index, and the illuminance when the white LED was turned on are described.

To the coating solution having a solid content ratio of 3.8%, a metal complex dye Eisenspirone Yellow 3RH Special manufactured by Hodogaya Chemical Co., Ltd. was added in a solid content weight ratio of 0.16% and stirred and dispersed. The inner and outer surfaces of the straight pipe cover were applied by dip (immersion) to the filled bath.
It dried at 120 degreeC x 1 minute, and laminated | stacked the transparent film on the inner and outer surface of a straight pipe cover. (Number 4)
The color of the product cover was light orange.

As a result, the illuminance was hardly changed as compared with No. 2, and the color rendering index was Ra = 98, R9 to R15 = 82 to 100.
By using an orange complementary dye, the illuminance of white LED straight tube illumination is not reduced and the color rendering is improved.

Comparative Example 1

Add 0.26% of the metal complex dye Eisenspirone Blue 2BNH manufactured by Hodogaya Chemical Industry Co., Ltd. in a solid weight ratio to the coating liquid with a solid content ratio of 3.8%, and stir and disperse to fill the coating liquid. The inner and outer surfaces of the straight pipe cover were applied by dip (immersion) to the bath. It dried at 120 degreeC x 1 minute, and laminated | stacked the transparent film on the inner and outer surface of a straight pipe cover. (Number 5)
The color of the product cover was light blue.

As a result, the illuminance decreased by 2% compared to the blank cover (No. 1), and the color rendering index was Ra = 96, R9 to R15 = 73 to 98.
The use of a blue dye system having the same color as blue having the peak wavelength of the white LED element, and the addition concentration exceeded the appropriate range, resulting in a decrease in illuminance of the white LED straight tube illumination, and the color rendering performance also decreased.

(1) Illuminance Illuminance meter Illuminance meter ISO-TECH ILM1332A was used.
(2) Refractive index Abbe refractometer NAR-2T manufactured by Atago Co., Ltd. "Measured wavelength: measured at 550 nm.
(3) Color temperature, color rendering index Konica Minolta Co. Color rendering illuminometer Measured with CL-70F.
(4) Measurement of straight pipe coating thickness after drying The center part of the straight pipe is divided in half, and the Si peak intensity is counted by Rigaku Co., Ltd. “Portable component analyzer XL3t silicon draft detector”. Measure.

The present invention relates to a plastic cover that can meet diversified optical characteristics needs in straight tube LED lighting.

An illumination device having a white LED element that emits emitted light through an illumination cover made of polycarbonate resin, and capable of increasing an average color rendering index: Ra, special color rendering index (Ri) R9 to R15 Regarding color rendering cover.
The white LED element is a lighting device including a blue light emitting diode light source and a yellow phosphor in a fluorescent part.

Cross section of cylindrical polycarbonate resin cover Cross section with LED lighting module Perspective view of coating on the inner and outer surfaces of the polycarbonate resin cover

1. 1. Polycarbonate resin cover 2. Slide claw part LED module4. 4. Aluminum mount 5. Coating inner surface Coating exterior

Claims (2)

A straight tube type lighting device having a white light emitting diode element (LED element) having a correlated color temperature of 4000 to 4500 K at which emitted light is emitted through an illumination cover made of polycarbonate resin, the illumination cover being an organic material containing a metal complex dye A high-color-rendering cover for straight tube type LED lighting having a coating film on both sides and having an average color rendering index of emitted light: Ra of 95 or more and a special color rendering index of (R9 to R15) in the range of 80 to 100. In a method of forming an organic transparent resin film by coating (dipping and drying) a coating solution in which an organic transparent resin and a metal complex dye are dispersed in a diluting solvent on both sides of an outer shell cover made of a polycarbonate resin, the resin of the organic transparent resin is used. The method for producing a high color rendering cover for straight tube LED lighting according to claim 1, wherein the metal complex dye is added and colored in a range of 0.1% to 0.2% by weight with respect to the solid content.

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