JPS6159303A - Plastic optical fiber - Google Patents

Abstract

PURPOSE:To improve flexibility, environmental resistance characteristic, scratching resistance, etc. by constituting the core layer of an org. polymer having crosslinked structure and joining a light transmittable body consisting of an org. polymer or inorg. glass having high hardness to at least one end thereof. CONSTITUTION:The core layer 1 is formed of the org. polymer (e.g.;silicone resin, bisallyl carbonate resin) having the crosslinked structure of >=1.41 refractive index and the clad layer 2l consisting of the transparent org. polymer (e.g.; polytetrafluoroethylene, tetrafluoroethylene/ethylene copolymer) having the refractive index lower by <=0.01 than the refractive index of the core is provided on the outside circumference of the core 1. The light transmittable body 3 consisting of the transparent org. polymer (e.g.; polystyrene, polymethyl methacrylate) or inorg. glass having >=40 Rockwell hardness is joined to at least one end thereof by which the intended plastic optical fiber is obtd.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a plastic optical fiber whose core component is a resin component having a crosslinked structure with excellent flexibility and environmental resistance. In particular, it relates to plastic optical fibers with improved damage resistance at their ends.

[Conventional technology]

Conventionally, inorganic glass-based fibers have been known to have excellent optical transmission properties over a wide range of wavelengths, but synthetic fibers have poor workability, are weak against bending stress, and are expensive. Light transmitting fibers based on resin have been developed. Light transmitting fibers made of synthetic resin have a core-clad structure, with a core made of a polymer with a high refractive index and good light transmittance, and a cladding layer made of a transparent polymer with a smaller refractive index. Obtained by manufacturing fibers. The polymer useful as a core component with high light transmittance is preferably an amorphous material, and polymethyl methacrylate or polystyrene is generally used.

Among these core component polymers, polymethyl methacrylate has excellent transparency, mechanical properties, thermal properties, weather resistance, etc., and is used industrially as a core material for high-performance plastic optical fibers.

However, even this plastic light transmitting fiber made of polymethyl methacrylate does not have sufficient flexibility, and if the diameter exceeds 1 mm, it is rigid and easily breaks, allowing it to transmit a large amount of light. In applications requiring a large diameter such as light guides, sufficient characteristics cannot be exhibited, and there is a need for the development of large diameter, flexible light transmitting fibers.

In addition, the glass transition temperature of polymethyl methacrylate is 100°C, and plastic optical fibers with a core of polymethyl methacrylate cannot be used at all if the environmental conditions exceed 100°C. Expanding the use of plastic optical fibers is hampered by their poor chemical resistance and water resistance.

As a plastic optical fiber that can solve these problems, Japanese Patent Application Laid-Open No. 57-88405 and Japanese Patent Application Laid-Open No. 57-884
Publication No. 102604 discloses an EA related to plastic optical fibers containing silicone rubber as a core component.

[Problem that the invention seeks to solve]

Optical fibers containing silicone rubber as a core component shown in these prior inventions have rubber elasticity and low hardness. Difficult to process smoothly,
Moreover, during processing or use, peeling occurs at the core-clad interface on the end face, causing dust to enter the peeled interface and reducing the optical transmission characteristics of the optical fiber. [Means for Achieving] Therefore, the present inventors conducted studies to develop a plastic optical fiber having a core component of an organic polymer having a crosslinked structure that does not have the above-mentioned disadvantages, and as a result, completed the present invention.

The gist of the present invention is to have a core made of an organic polymer having a crosslinked structure with a refractive index of 1.41 or more, and a core made of an organic polymer having a crosslinked structure with a refractive index of 1.41 or more, and a core that is provided on the outer periphery of the core and has a refractive index that is 0.01 or more lower than the refractive index of the core. A plastic optical fiber having a cladding layer made of a substantially transparent organic polymer, and a transparent material made of a transparent organic polymer or inorganic glass having a Rockwell hardness of 40 or more is bonded to at least one end. This is a plastic optical fiber that is characterized by:

Examples of the organic polymer having a crosslinked structure constituting the core in the present invention include silicone resin, bisallyl casenate resin,
Allyl phthalate resin, acrylic resin with a crosslinked structure, etc. can be used, but among these, when considering the handleability of the optical fiber of the present invention, a tensile strength of 0゜5 k'i/1 m"υ or more is recommended. , a crosslinked organic polymer having an elongation of 20% or more is preferable. Among these resins, silicone resins are particularly preferable, and the following types of crosslinking reactions can be used, for example.

(However, R shall represent a hydrogen atom or any monovalent organic group.) The refractive index of the crosslinked organic polymer constituting the core must be 1.41 or more; The ratio may be selected as appropriate depending on the numerical aperture required of the plastic optical fiber of the present invention.

When forming the crosslinked organic polymer that constitutes the core,
In addition to crosslinking by addition reaction as described above, crosslinking can also be carried out using peroxide, light, radiation, Lewis acid catalyst, etc.

The component of the rad layer that can be used in the present invention is a substantially transparent organic polymer (preferably a thermoplastic organic polymer) having a refractive index lower by 0.01 or more than the refractive index of the core component polymer. is necessary.

If the difference in refractive index is less than 0.01, not only will the numerical aperture of the resulting optical fiber be small, but also the transmission loss will be extremely large.Furthermore, if the refractive index of the cladding layer component is larger than that of the core component, the light This is because it is not transmitted at all.

Examples of the low refractive index thermoplastic polymer used as the cladding layer component of the plastic optical fiber of the present invention include, for example, polytetrafluoroethylene (nd=
1.35), tetrafluoroethylene//f-fluoroalkyl vinyl ether copolymer (1d=l, 34-1
．． 36), tetrafluoroethylene/hexafluoropropylene copolymer ("d = l, 34), yl
! J dichlorolifluoroethylene (na == l, 4
25), tetrafluoroethylene/ethylene copolymer (nd=1.40), polyvinyl fluoride (nd
= 1.42), polyvinylidene fluoride (nd = 1
．． 47), tetrafluoroethylene/vinylidene fluoride copolymer (“d == 1.38 to 1.42),
Other various fluorinated alkyl methacrylate polymers, comonomers (nd = 1.38 to 1.48), blends of polyvinylidene fluoride and polymethyl methacrylate (nd - 1,43 to 1.48), etc. In addition to fluorine-based polymers, poly4-methyl-1-pentene (n4=x, 46)
, polymethyl methacrylate) (nd=1.49) can be used if the core has a high refractive index.

The diameter of the core of the plastic optical fiber of the present invention is not only within the range of conventional optical fibers of 5 to 3000 μm, but due to its excellent flexibility, it is even thicker than 3000 μm, and can be used for ultra-thick optical transmission lines of about 50 mm. Manufacturable.

It is necessary for the thickness of the cladding layer to be 1 μm or more in order to achieve good optical transmission by total reflection of the obtained optical fiber, and the upper limit of the thickness of the cladding layer is selected as appropriate depending on the purpose of use. can do.

The transparent organic polymer used for the transparent body bonded to at least one end of the optical fiber of the present invention meets ASTM D785.
It is necessary that the Rockwell hardness measured on the M scale is 40 or more. If the hardness is less than 40, the processability of the optical fiber will be poor and the container will be damaged during use, resulting in a decrease in its light transmission properties.

Examples of transparent organic polymers with a hardness of 40 or higher include polystyrene, polymethyl methacrylate, polybenzyl methacrylate, and polycarbonate. Various shapes such as a spherical convex lens shape, a concave lens shape, and a cylindrical shape can be used. The connection of this transparent material to the optical fiber is as shown in (a) in Figure 1.
A bonding method by pasting or a bonding method in which most of the transparent material is inserted into the cladding layer as shown in (c) is also possible, but the most desirable form is a transparent material as shown in Figure 1 (b). A part of the light body is inserted into the cladding layer at the tip of the optical fiber. In these figures, 1 is a core having a crosslinked structure, 2 is a cladding, and 3 is a transparent body.

By adopting such a configuration, the bonding state between the optical fiber and the light-transmitting material can be made extremely good, and the problem of peeling at the core (9,)-clad interface can be almost completely eliminated when processing the tip of the optical fiber. can be prevented.

The plastic optical fiber of the present invention is produced by shaping the organic polymer constituting the cladding layer into a hollow fiber shape, and then using a suction method to form a fluid precursor into the hollow fiber to form the crosslinked organic polymer that will become the core component. It is preferable that the crosslinking reaction is started after the fluid is injected by a press injection method and it is confirmed that the fluid is in a stationary state. Note that the light-transmitting body may be joined after the core component is in a fluid state before the crosslinking reaction, or after the crosslinking reaction.

The core-forming precursor should be purified by filtration with a membrane filter having a pore size of 0.05 to 10 μm, preferably 0.105 to 1 μm, before being shaped, and then irradiated with a visible laser beam to use a precursor in which almost no bright spots are observed. is necessary in order to reduce the transmission loss of the optically transmitting fiber. By using such a purified precursor, 600 ~
1000 dB transmission loss due to 700 nm visible light
It is easy to reduce the transmission loss to less than 100 dB/km, but if the incorporation of foreign matter and dust is completely prevented (C10), it is possible to reduce the transmission loss to less than 100 dB/km.

〔Effect of the invention〕

The plastic optical fiber of the present invention is similar to the conventional plastic optical fiber #! Made of high-performance, highly reliable light transmitting fiber that has flexibility, heat resistance, cold resistance, chemical resistance, and vibration resistance that exceeds the five resistances of fibers, and can be used in extremely harsh environments. The plastic optical fiber of the present invention is capable of optical communication over several hundred meters, and also prevents peeling of the core-clad interface during end face processing and has excellent damage resistance. The significance is extremely large.

The plastic optical fiber of the present invention is suitable for controlling light in moving bodies such as automobiles, ships, and airplanes, especially in parts such as engine rooms that have severe environmental conditions.

Hereinafter, the present invention will be explained in detail with reference to Examples.

In each example, Me represents a methyl group, pH represents a phenyl group, and Vi represents a vinyl group.

In addition, all parts and parts in the examples are parts by weight and Mt.
Indicates %1. , all viscosities are values measured at 25°C.

Example 1 To 95.0 parts of a filtrate obtained by filtering a mixture with a polytetrafluoroethylene having a viscosity of 700 centistokes through a polytetrafluoroethylene filter having a pore size of 0.1 μm, 5.0 parts of pbs t÷08iPh2H), and 2
- chloroplatinic acid 5/100 dissolved in ethylhexanol
10,000 parts of polytetrafluoro x with a pore size of 0.1 μm
A core component precursor was prepared by mixing and defoaming in a clean room at P3m using a Chin L/N filter.

The physical properties of the polysiloxane obtained by heating this precursor at 150° C. for 2 hours were as follows.

Refractive index nD1.51 +, tensile strength 2 kl'm"
e elongation was 60 inches.

On the other hand, 325 tedrafluoroethylene/hexafluoropropylene, 85/15 copolymer (nd=1.34)
Melt extrusion through blow molding nozzle at °C, inner diameter 911II
A hollow fiber having an outer diameter of 10 mmφ and an outer diameter of 10 mmφ was obtained.

Prepare two pieces of this hollow fiber cut into looms, connect one end to a vacuum pump, fill the other end with the above-mentioned core component precursor, and both ends of one hollow fiber have a Rockwell hardness of 8.
0 outer diameter 9. : A cylindrical convex plastic lens with a length of 3++Im and 10 mm is inserted into the hollow fiber as shown in Figure 1 (b) so that no air bubbles enter between the contact point of the precursor and the cylindrical convex lens, and the other The hollow fibers were not subjected to such treatment.

Two hollow fibers filled with the above-mentioned precursor were heat-treated at 150° C. for 1 hour to complete crosslinking of the precursor, and a plasti-based optical fiber was produced.

Each of the two types of plastic optical fibers obtained was
The light source was cut with a knife into the same length as the light source, and the amount of light emitted was measured. At this time, the convex lens side of the optical fiber to which the convex lens was attached was attached to the light source.

The amount of light emitted from the optical fiber with a convex lens was 2.3 times brighter than that without a convex lens.

Example 2 An optical fiber was obtained in the same manner as in Example 1, except that the cylindrical convex lens in Example 1 was replaced with a transparent glass sphere with a diameter of 9.5 Wm, and the lenses were attached to both end faces.

When this optical fiber was used to illuminate the inside of a dark box heated to 160°C, the brightness did not change even after 24 hours.

[Brief explanation of drawings]

FIGS. 1C, 1B, and 1E are cross-sectional views of the tip of the plastic optical fiber of the present invention.

Claims (1)

[Claims] A core made of an organic polymer having a crosslinked structure with a refractive index of 1.41 or more, and a substantially transparent organic polymer provided around the outer periphery of the core and having a refractive index lower than the refractive index of the core by 0.01 or more. 1. A plastic optical fiber having a cladding layer comprising a cladding layer, the optical fiber having a transparent material made of a transparent organic polymer or inorganic glass having a Rockwell hardness of 40 or more bonded to at least one end. .