JPH052115A - Hollow light transmission fiber - Google Patents

Abstract

PURPOSE:To inexpensively obtain a hollow light guide which is flexible and is small in diameter by melt composite molding of a hollow fiber structural body consisting of many islands of a transparent core resin having a high refractive index and a transparent sheath resin of a low refractive index enclosing these islands. CONSTITUTION:The hollow bar-shaped hollow light transmission fiber is the hollow fiber structural bode consisting of >=100 pieces of the many islands of the transparent core consisting having the high refractive index and the transparent sheath resin of the low refractive index enclosing these islands and is formed by melt composite molding. The molten core resin and sheath resin are together supplied to a composite spinning die and the core polymers are extruded from a die plate bored with many holes in such a case. The many fibers in this molten state are thus made to flow out. The sheath resin in the molten state is injected around these core fibers to form waveguides consisting of the cores as the islands and the sheath as the sea when viewed from the section. Another fluid is introduced into the central part of such sea-and-island structural body. This fluid may be preferably gas, such as gaseous nitrogen or air and may, in some cases, be such resins which can be dissolved away by washing or by org. solvents, etc., after the molding.

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The hollow light guide fiber of the present invention has an image optical fiber, an optical fiber, or a conductive wire disposed in its hollow portion, and introduces light into the hollow light guide fiber to illuminate the tip portion. It is used as a light guide, and is used in the medical field and measurement field as an endoscope and an optical sensor.

[0002]

2. Description of the Related Art A conventional hollow optical fiber has a hollow central portion as shown in FIG. 2, a first layer is a sheath layer, a second layer is a core layer, and a third layer is a third layer.
A hollow three-layer structure fiber having a layer as a sheath layer,
Furthermore, as shown in FIG. 3, around the center fiber,
There is one in which a large number of fibers smaller than the diameter are arranged and fixed.

On the other hand, an image-plastic fiber having a sea-island structure in which the core is an island and the sheath is the sea is disclosed in US Pat.
No. 35, this structure has no hollow inside.

[0004]

A drawback of the hollow light guide fiber having a three-layer structure is that since the core layer is integrally formed, the rigid core tube does not have flexibility, so that when it is bent, it easily buckles. If it is scratched, it has a drawback that it is easily broken.
In addition, even when the fiber is inserted into the hollow portion, there is a drawback that there is no freedom of expansion and contraction and insertion is difficult. In addition, a large number of optical fibers having a small diameter are arranged around the central fiber, and those surrounding the optical fiber require complicated processing work, which increases the burden of manufacturing cost. In order to easily carry out this method, there is also a method of winding a sheet of plastic optical fiber in a coil winding shape, but the hollow light guide fiber obtained by this method can only be straight tube and is difficult to bend, so it is used by bending Not suitable for use.

[0005]

The present invention is a hollow light guide fiber having a new structure. That is, the present invention is a hollow fiber structure, which comprises a large number of 100 or more islands of a transparent core resin having a high refractive index and surrounding transparent island resins having a low refractive index. It is a hollow rod-shaped hollow light guide fiber as shown in FIG. 1, obtained by melt-compositing a core resin and a sheath resin together.

As can be seen from the cross section of the hollow light guide fiber, as shown in FIG. 4, a sea-island structure having a core as an island and a sheath as the sea and a core and a sheath as concentric islands and surrounding It also includes a sea-island structure filled with the third resin as shown in FIG. In order to obtain the hollow light guide fiber of the present invention, the molten core resin and sheath resin are supplied together to a composite spinning die, and first, the core polymer is extruded from a die plate having a large number of holes, and a large number of the molten state is obtained. Pour out the core wire of. Then, a molten sheath resin is injected around the core wire, and when viewed in cross section, a waveguide having a core as an island and a sheath as the sea is formed, and another fluid is formed at the center of the sea-island structure. To introduce. The fluid is preferably a gas such as nitrogen gas or air, but in some cases, it may be a resin that can be dissolved and removed by washing with water or an organic solvent after molding. More specifically, each of the core resin and the sheath resin is subjected to composite spin molding of a sea-island structure using a known composite spinning die, for example, an apparatus as described in US Pat. No. 3,556,635, and is still melted. Before the sea-island structure in a fixed state is fixed, in order to form a hollow portion, a nozzle for introducing another fluid is arranged to introduce the fluid, or a composite spinning die for forming the sea-island structure is previously prepared. It can also be obtained by forming a donut shape so that another fluid flows in the central portion. After that, the molten resin having the hollow portion formed therein may be drawn down to a desired small diameter while cooling the resin.

Since the purpose of the hollow light guide fiber is mainly for a light guide, each sea-island structure does not have to have a regular shape as required for an image fiber.
Some disturbance is allowed. More importantly, it is more important that the hollow light guide fiber be flexible and that it should not be broken even if some force is applied when inserting the fiber into the hollow portion.

The hollow light guide fiber of the present invention can be used by partially tearing or unraveling the hollow light guide fiber if a sheath resin is appropriately selected. It has a feature that the output light can be easily extracted. The present invention is also characterized in that it is an aggregate composed of fine cores, and the number of islands is required to be 100 or more. Since the number of islands is large, the wall surface of the hollow light guide fiber is smooth and the directionality when bent is lost, so that the number is preferably 500 to several thousand.

The outer diameter and inner diameter of the hollow light guide fiber can be adjusted according to need, but the outer diameter is 0.1 mm to 5.0 m.
A product having an inner diameter of 0.05 mm to 4 mm can be easily manufactured. In addition, you may stretch and heat-process as needed. As a standard for selecting a resin when manufacturing such a multi-core fiber, a resin conventionally known as a core resin of a plastic optical fiber can be used as the core resin. For example PM
MA-based resin, polycarbonate-based resin, polystyrene-based resin, etc.
M-1238, at 230 ℃, the value of 3.8kg weight is 0.1
Those having about g / 10 minutes to 100 g / 10 minutes are preferable. On the other hand, as the sheath resin, those conventionally used as the sheath of a plastic optical fiber can be used, but those having relatively good fluidity when melted are preferable. Suffice it to say, the melt flow index is ASTM-12.
The value of 3.8 kg weighted at 38 and 230 ° C. is preferably 10 g / 10 minutes to 200 g / 10 minutes, and may have good fluidity. As a combination of the core polymer and the sheath polymer, for example, when the core polymer is a PMMA resin, the sheath resin is preferably a fluoroalkyl methacrylate resin, an α-fluoroalkylfluoroalkyl acrylate resin, a vinylidene fluoride resin, or the like. When the polystyrene resin is used as the core, PMMA-based resin, ethylene vinyl acetate copolymer and the like are preferable, and when the polycarbonate resin is used as the core, the sheath resin is PMMA-based resin or PMMA-based resin. Vinylidene fluoride resin,
An example of using 4-methylpentene-1 resin is given. As for the area ratio of the island of the core and the sea of the sheath, the one with the larger area of the core is preferable for the use of the light guide, and is 50% to 95%.
It is better to occupy the degree with the core area. Further, when the sea part is formed using the third resin, the resins given as the above-mentioned examples, those obtained by coloring them, and those having rubber elasticity are preferable.

The outer diameter of the hollow light guide fiber and the inner diameter of the hollow portion are
The area ratio can be determined according to the actual application, but it goes without saying that the area ratio can be controlled by the flow rate of the fluid supplied to the hollow portion, the diameter of the nozzle of the fluid introduced into the hollow portion, and the like. When using the hollow light-guiding fiber of the present invention, an image optical fiber or an optical fiber is inserted into the hollow light-guiding fiber, but the hollow light-guiding fiber remains attached to the image fiber while maintaining its shape. It is also possible to tear one end or the middle of the hollow light guide fiber so that the hollow light guide fiber is branched from the image fiber or the like to enable connection to a light source or a photodetector. In this case, tearing causes partial peeling of the sheath at that portion, causing some light leakage, but this is not a problem. As a fiber suitable for such an application, a core is made of polycarbonate, a sheath is made of ethylene vinyl acetate copolymer, or a core is made of polycarbonate, and the sheath is made of 4-methylpentene-
It is preferable that both the core resin and the sheath resin as described in 1 are made of a resin having elongation, and the workability of connection is easy. Of course,
When PMMA is used for the core and vinylidene fluoride resin is used for the sheath, relatively good results are obtained.

On the outside of the hollow light guide fiber of the present invention, polyethylene, PVC resin, ethylene vinyl alcohol resin,
A protective coating can be provided with an antithrombogenic material such as Teflon resin or other fluororesin, and it can be provided for medical use.

[0012]

EXAMPLES Next, the present invention will be described in more detail by way of examples.

[0013]

[Example 1] The die was installed in a die with 1000 provided while flowing nitrogen gas from a nozzle provided at the center of the die.
A die was used to extrude the core resin from the hole at the same time, and at the same time, simultaneously mold the core resin to be extruded while covering the core resin. The core resin has a melt flow index of A
STM-1238, PMMA resin with a value of 3.8 kg weighted at 230 ° C. of 1.5 g / 10 min, while sheath resin is vinylidene fluoride, trifluoroethylene, hexafluoroacetone, melt flow index 35 g / 1
The resin for 0 minutes was used, the die temperature was set to 230 ° C., the nitrogen gas was set to about atmospheric pressure, and the molten core resin was 0.85 k
g / hr, and the sheath resin was flown at 0.15 kg / hr. At the die exit, the hollow molten strand that has already become a sea-island structure is stretched, and the outer diameter is 1.0 mm and the inner diameter is 0.5 mm
The hollow light guide fiber of was obtained.

It has been confirmed that this fiber can transmit light in a room even if it has a length of 15 m, and is particularly useful as a light guide for a short distance of about several m.

[0015]

Example 2 A polycarbonate resin having a molecular weight of 15,000 was used as the core resin, and an ethylene vinyl acetate copolymer having a vinyl acetate copolymerization ratio of 25% was used as the sheath resin. In the same manner as in Example 1, the outer diameter is 1.0 mm and the inner diameter is 0.6.
The resulting hollow light guide fiber of 5 mm has a fiber length of 5 m.
But it transmitted the light from the room.

An image fiber made of plastic having a diameter of 0.5 mm was inserted into the hollow light guide fiber in an amount of 1.0 m, and the hollow light guide fiber was further divided with a razor to branch as shown in FIG. With the structure. Due to this structure, it was easy for light from the light source to enter.

[0017]

EFFECTS OF THE INVENTION A hollow light guide having a small diameter and flexibility can be provided at low cost.

[Brief description of drawings]

FIG. 1 is a simplified cross-sectional view of the present invention.

FIG. 2 is a cross-sectional view of a conventional hollow light guide fiber.

FIG. 3 is a cross-sectional view of a conventional ratchet-shaped hollow light guide fiber.

FIG. 4 is a cross-sectional view of a hollow light guide fiber having a sea-island structure in which a core is an island and a sheath is the sea.

FIG. 5 is a cross-sectional view of a hollow light guide fiber having a sea-island structure in which a core and a sheath are concentric islands and the third resin is sea.

FIG. 6 is a schematic view of an example in which the hollow light guide fiber of the present invention is branched and used.

[Explanation of symbols]

 1 cavity 2 sheath layer 3 core layer 4 sheath layer 5 core (island) 6 sheath (sea) 7 sheath 8 core 9 sea 10 objective lens 11 image optical fiber 12 hollow light guide fiber 13 eyepiece lens 14 light source

Claims (1)

Claim: What is claimed is: 1. A hollow fiber structure comprising a large number of 100 or more islands of a transparent core resin having a high refractive index and a surrounding transparent island resin having a low refractive index, Hollow light guide fiber in the shape of a hollow rod formed by melt compounding.