JPH10288713A - Plastic optical fiber - Google Patents

Abstract

PURPOSE: To obtain a plastic optical fiber which is capable of emitting white light without coloring the light and has high heat resistance by incorporating coloring agents having the max. absorption in a specific wavelength region into a clad layer. CONSTITUTION: This plastic optical fiber consists of a core layer and clad layer made of plastic. The clad layer contains the coloring agents having the max. absorption wavelength in the visible light region within a range of 550 to 700 nm. The resin constituting the clad layer is preferably a curing type silicone resin in terms of the mixing state of the coloring agents and productivity. In the case of the curing type silicone resin, the resin is in a liquid state before curing and may be uniformly dispersed or dissolved simply by blending the coloring agents. The intrusion of impurities is thus minimized. The examples of the using coloring agents include inorg. pigments of cobalt purple, manganese purple, ultramarine, etc., org. pigments, such as fast violet B, methyl violet rake, etc., and oil-soluble dyes and water-soluble dyes of an antraquinone system, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic optical fiber used for illumination and a fiberscope.

[0002]

2. Description of the Related Art Although a plastic optical fiber has a relatively large transmission loss, it has a large aperture coefficient and is flexible, and can be made large in diameter. The use of is expected. A plastic optical fiber mainly used as an optical light guide has a core layer formed of polymethyl methacrylate. However, the plastic optical fiber having this polymethyl methacrylate core layer has poor heat resistance, and its heat resistance is about 85 ° C. To improve heat resistance, a plastic optical fiber having a core layer made of polycarbonate has recently been developed. However, when light enters a plastic optical fiber having this polycarbonate as a core layer, the emitted light becomes yellowish and white light is emitted. Light cannot be transmitted as it is. To improve this, we added a blue dye to the polycarbonate in the core layer,
Although whitening has been studied, transmission loss has been significantly increased, and an increase in transmission loss has been observed due to deterioration of the core layer at high temperatures due to dye, and it has been difficult to make it usable.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a plastic optical fiber having high heat resistance and capable of emitting white light without coloring.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to overcome the above-mentioned disadvantages of the conventional plastic optical fiber, and as a result, the coloring agent having the maximum absorption in a specific wavelength region is contained in the cladding layer. It has been found that the light can be transmitted as white light by performing this, and the present invention has been completed based on this finding. That is, the present invention provides (1) a plastic optical fiber comprising a plastic core layer and a cladding layer, wherein the cladding layer contains a colorant having a maximum absorption wavelength in the visible light region in the range of 550 to 700 nm. (2) The plastic optical fiber according to (1), wherein the core layer is made of polycarbonate.
(3) The plastic optical fiber according to (1), wherein the cladding layer is made of a silicone resin containing a coloring agent.

[0005] In the present invention, the resin constituting the cladding layer includes tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoroalkylvinyl ether copolymer, ethylene-tetrafluoroethylene copolymer, and fluorinated polymethacrylic. Examples thereof include fluororesins such as methyl acid, Teflon AF, and Cytop, silicone resins, polymethylpentene, imidized acrylic resins, and the like. Curable silicone resins are preferred from the viewpoint of the mixing state of the colorant and productivity. In the case of a curable silicone resin, it is in a liquid state before curing, and can be uniformly dispersed or dissolved by simply blending a colorant, and the contamination of impurities can be minimized. The amount of the coloring agent to be added varies depending on the type of the coloring agent and the use environment, but is usually in the range of 0.005 to 5% by weight, preferably 0.005 to 0.5% by weight in the clad layer. is there. If the amount of the coloring agent is too small, the effect is insufficient,
If the amount is too large, the transmission loss increases remarkably or the emitted light is colored blue. The colorant used in the present invention only needs to have a maximum absorption wavelength in the visible light region in the range of 550 to 700 nm. Specific examples thereof include inorganic pigments such as cobalt purple, manganese purple, ultramarine, navy blue, cobalt blue, and celian blue, fast violet B, methyl violet lake, alkali blue lake, peacock blue lake, Victoria blue lake, and metal-free phthalocyanine. Organic pigments such as blue, phthalocyanine blue, fast sky blue, indanthrene blue RS, and indanthrene blue BC, anthraquinone-based, phthalocyanine-based, oil-soluble dyes such as triphenylmethane-based, and water-soluble dyes. These may be used in combination of two or more.

Among them, organic pigments and oil-soluble dyes are preferred from the viewpoint of compatibility with the cladding layer resin, and phthalocyanine pigments and dyes are more preferred from the viewpoint of heat resistance. By using a resin mixed with such a coloring agent as the cladding layer, when white light enters such a plastic optical fiber, white light can be emitted without yellowing. Also, by using polycarbonate as the core layer, it also has heat resistance of about 120 to 130 ° C., and can withstand use at high temperatures. Furthermore, compared to the case where a coloring agent is added to the core layer, since the coloring agent is dispersed or dissolved in the cladding layer, scattering by the coloring agent can be minimized, and the coloring agent during processing is also used. The increase in transmission loss due to deterioration of transmission and the increase in transmission loss when used at high temperatures are small. In addition, when a coloring agent is added to the cladding layer, particularly in the case of a curable silicone resin, mixing can be easily performed, so that emission light characteristics can be easily controlled.

The mixing of the colorant into the cladding layer resin of the present invention is carried out by a twin-screw extruder in the case of ordinary fluororesin. Further, in the case of Teflon AF or Cytop, it is mixed by dissolving or dispersing it in a soluble fluorine-containing solvent and then adding a coloring agent. In the case of a thermosetting silicone resin, it can be mixed by dissolving or dispersing a colorant in the resin and curing the same. The plastic optical fiber of the present invention can be formed by an extrusion method or other methods. When a thermosetting silicone resin to which a coloring agent is added is used for the cladding layer, after the core layer is formed by an extrusion method or the like, this is passed through a die to which the above silicone resin is added, and then passed through a heating furnace to be cured. By doing so, a clad layer is obtained. The outside of the cladding layer may be protected with a suitable resin to protect it. The protective layer resin is not particularly limited, and examples thereof include polyarylate, polycarbonate, polysulfone, ethylene-tetrafluoroethylene copolymer, and hexafluoropropylene-tetrafluoroethylene copolymer.

[0008]

Next, the present invention will be described in more detail with reference to examples. The characteristics in the examples were measured by the following methods. -Transmission loss It measured using the 660 nm LED as a light source by the 5m-1m cutback method. Emission light characteristics at each wavelength White light was incident on a plastic optical fiber cut into 2 m and subjected to terminal treatment via a monochromator, and the emission light was measured with a photomalmeter. The measurement was continuously performed at a rate of 60 nm / min between 890 nm and 350 nm. A tungsten lamp was used as a white light source.

Example 1 Two-part mixed type thermosetting silicone resin (X38-091H)
AB: 100 g of Shin-Etsu Chemical Co., Ltd., 0.3 g of a coloring agent (Cyanine Blue 2035, manufactured by Sanyo Pigment Co., Ltd.) was added, mixed well, and defoamed to prepare a clad material. Polycarbonate AD-9000TG manufactured by Teijin Chemicals Limited as the core layer
(Glass transition temperature: 142 ° C.) was added to the resin introduction path, and spinning was performed at a head temperature of 245 ° C. A die was set in the middle of the spinning, a clad material made of the above-mentioned thermosetting silicone resin was added thereto, and the mixture was further cured in a lower furnace to obtain a plastic optical fiber. The obtained plastic optical fiber had a core diameter of 0.96 mm and an outer diameter of 1.02.
mm. The transmission loss is 1000 dB / km (6
60 nm: LED). When the plastic optical fiber 2m was cut and white light was incident, the outgoing light was almost white light. When the emission light characteristics at each wavelength were measured, the emission light characteristics were almost flat in the visible light region as shown in FIG.

Example 2 Two-part mixed type thermosetting silicone resin (X38-091H)
(AB) 0.02 g of a coloring agent (Oil Blue IIN, manufactured by Orient) was added to 100 g, mixed well, and then defoamed to prepare a clad material. Polycarbonate AD-9000TG as a core layer was added to the resin introduction path, and a head temperature of 2
The fiber was spun at 45 ° C., a die was set in the middle of the spinning, the clad material made of the above-mentioned thermosetting silicone resin was added thereto, and the mixture was further cured in a lower furnace to obtain a plastic optical fiber. The obtained plastic optical fiber had a core diameter of 0.96 mm and an outer diameter of 1.02 mm. The transmission loss is 1250dB / km (660nm: LED)
Met. When the plastic optical fiber 2m was cut and white light was incident, the outgoing light was almost white light. When the emission light characteristics at each wavelength were measured, the emission light characteristics were almost flat in the visible light region as shown in FIG.

Comparative Example AD-9000TG was added as a core layer to the resin introduction path.
Spinning was performed at a head temperature of 245 ° C. A die was set in the middle of spinning, and a two-component mixed type thermosetting silicone resin (X38-091HAB) was added thereto, and the mixture was cured in a lower furnace to obtain a plastic optical fiber. The obtained plastic optical fiber has a core diameter of 0.96 mm and an outer diameter of 1.
02 mm. The transmission loss is 400 dB / km
(660 nm: LED). When the plastic optical fiber 2m was cut and white light was incident,
The outgoing light was yellowish. Also, when the emission light characteristics at each wavelength were measured, it was confirmed that the absorption intensity was higher at shorter wavelengths in the visible light region as shown in FIG.

[0012]

According to the plastic optical fiber of the present invention, the transmitted white light is not colored yellow. In addition, the plastic optical fiber of the present invention has an excellent effect in that the core layer is made of polycarbonate and the clad material contains a specific coloring agent, so that the heat resistance is excellent and the emission characteristics are uniform in the visible light region. To play. Such a plastic optical fiber having excellent heat resistance is applicable to a high-output light source, is used as an optical light guide or the like, and is used in medical devices, automobiles, and the like.

[Brief description of the drawings]

FIG. 1 is a graph showing transmission loss at each wavelength of a plastic optical fiber of an example of the present invention and a comparative example.

Claims (3)

[Claims] 1. A plastic optical fiber comprising a plastic core layer and a cladding layer, wherein the cladding layer has a maximum absorption wavelength in a visible light region of 550 to 700.
A plastic optical fiber containing a coloring agent in the range of nm. 2. The plastic optical fiber according to claim 1, wherein the core layer is made of polycarbonate. 3. The plastic optical fiber according to claim 1, wherein the cladding layer is made of a silicone resin containing the coloring agent.