JPH01164904A - Production of plastic optical fiber - Google Patents

Abstract

PURPOSE:To obtain a distributed index type optical fiber having good flexibility by combining an uncured transparent material which is non-volatile and has a refractive index n1 and uncured transparent material which is volatile and has a refractive index n2 at the specific relation held therebetween to a form a mixture which is specified in viscosity and spinning the mixture. CONSTITUTION:The mixture prepd. by selecting and combining the uncured transparent material which is non-volatile and has the refractive index n1 and the uncured transparent material which is volatile and has the refractive index n2 so as to maintain the relation n1>n2 and adjusting the viscosity thereof to 10<3>-10<5> poise is spun to form a yarn-like material and this yarn-like material is treated to evaporate the volatile material therefrom. The distributed index type plastic optical fiber having the good flexibility is thereby continuously and efficiently obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a gradient index plastic optical fiber in which the refractive index changes outward from the central axis of the optical fiber.

[Conventional technology]

Rod-shaped lenses in which the refractive index changes from the center of the transparent rod-shaped body toward the outer periphery are commercially available, and are usefully used as image transmission bodies in copiers.

[Problem that the invention seeks to solve]

However, these rod-shaped lenses are rigid and become extremely difficult to handle as the distance between the document and the light-receiving surface increases.Currently, electrical and mechanical methods are used to resolve this difficulty. As the image transmission distance increases,
There is a tendency for the difficulty to be doubled, and there is a demand for the development of an image transmitting body that is free from such difficulties and has good flexibility.

[Means for solving problems]

Therefore, the present inventors completed the present invention as a result of studies aimed at developing a gradient index optical fiber that can satisfy the above-mentioned requirements.

The gist of the present invention is to select and combine an uncured, non-volatile, transparent substance with a refractive index of n1 and an uncured, volatile, transparent substance with a refractive index of n2 so as to maintain the relationship nl > n2. A mixture with a viscosity of 103 to IO゜poise is spun into a yarn, and the yarn is subjected to volatilization treatment to remove volatile substances, or the mixture has a viscosity of 03 to 05.
Poise n.

The core is made of a substance with a refractive index of The main feature lies in the manufacturing method of the gradient index plastic fiber.

As mentioned above, the plastic optical fiber obtained by the present invention has a major characteristic that the refractive index decreases from its axis toward its outer periphery. One is transparent in the uncured state and the refractive index of the cured product is 01, and the other is transparent in the uncured state and the refractive index of the cured product is n2.
2, and uncured materials that can make such a cured product include methyl methacrylate (n = 1.49), styrene (n = 1.59),
Chlorstyrene (n=H, 61), vinyl acetate (n=
1.47), vinylidene fluoride (n=1.42),
+10-fluoropropylene (n=lj4), 0f(2
= 0(OH3)OOORf(n = 1.37~+, 4
0 ), and all of them are (OH2)I! 1
(OF2)nH, -c(at3), , ay2at2
aHycy3゜0H20F (CF3)2. CH2=
cHcoo*r (n = 137 to summer, 40), where W is -(CH2)rn(CF2)nH
, -CH20F2CHIPCF3. -0H (CF3),
0H2=OFGOOR', (n=1.37~1
．． 42), methacrylates and acrylates with n = 1.45 to 1.62, such as ethyl (
meth)acrylate, phenyl(meth)acrylate,
Benzyl (meth)acrylate, hydroxyalkyl (
meth)acrylate, alkylene glycol di(meth)
Acrylate, trimethylolpropane di- or tri(meth)acrylate, pentaerythritol di-, tri- or tetra(meth)acrylate, diglycerin tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, etc., diethylene glycol bisallyl carbonate, fluorine Examples include alkylene glycol poly(meth)acrylate. In order to adjust the viscosity of the uncured material to be used for spinning and to give the resulting filament a refractive index distribution from the center to the outside, it is possible to use a soluble polymer in the curable liquid material. Preferably, for example, polymethyl methacrylate (n=1.49), polymethyl methacrylate copolymer (n=1.47 to t50), poly-4-methylpentene-1 (n=146), ethylene/vinyl acetate copolymer ( n=1.46-1.50), polycarbonate (n=1.50-1.57), polyvinylidene fluoride (
n=1.42), vinylidene fluoride/tetrafluoroethylene copolymer (n=1.42-1.46), vinylidene fluoride/tetrafluoroethylene/hexafluoropropene copolymer (n=1.40-1.46) , polyfluorinated alkyl (meth)acrylate polymers, and the like.

The uncured material used in carrying out the present invention must be curable and have a viscosity of 10 to 10 poise. Breakage occurs, making it difficult to form a thread. On the other hand, when the viscosity is greater than 10 poise, the spinning operability becomes poor and it becomes difficult to obtain a thread with little diameter unevenness.

A gradient index optical fiber according to the present invention can be produced using, for example, a thread molding apparatus as shown in FIG. In Fig. 1, 11 is a part of the cylinder, 12 is a curable uncured material mixing part, 15 is a heater for adjusting viscosity, 14 is a piston, 15 is a spinning nozzle part, and +6 is an extruded uncured material. 17 is a processing section for imparting a refractive index distribution to the thread; 18 is a processing section for curing the uncured material; 20 is a take-up roller; The mold plastic original fiber, 21 is a winding part.

When carrying out the present invention, the refractive index n and n2 are 2
From the surface of a thread-like material spun with a predetermined viscosity, a volatile substance is selected as a mixture using more than one type of compound and has a relationship of nl > n2 and a refractive index of n. By volatilizing the high refractive index component called nl, it is made into a filamentous material with a refractive index distribution, and then hardening, or by coextruding the high refractive index component as a core and the low refractive index component as a sheath to create a filament with a low refractive index. By performing a treatment to diffuse the index component into the core component, the fiber is made into a refractive index distribution type fiber, followed by a curing treatment, thereby making it possible to produce the refractive index distribution type optical fiber, which is the object of the present invention.

In order to cure an uncured filament, it is preferable to interpose a thermosetting catalyst and/or a photocuring catalyst in the filament, and then perform heat treatment or light irradiation treatment.

As a thermosetting catalyst, a commonly used peroxide catalyst can be used, and as a photopolymerization catalyst, benzophenone, benzoin alkyl ether, 4'-isopropyl-2-hydroxy-2-methyl-propiophenone, 1-hydroxycyclohexylphenyl ketone, benzyl methyl ketal, 2,2-jethoxyacetophenone, chlorothioxanthone, thioxanthone compounds, benzophenone compounds, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, N
-Methyljetanolamine, triethylamine, etc. can be mentioned.

The refractive index distribution type optical 7-eyeper obtained by the present invention may further be provided with a coating layer having a low refractive index. 1,2.2-tetrahydrohebbutadecafluorodecyl acrylate, hexanediol diacrylate, neopentyl glycol diacrylate, dipentaerythritol hexaacrylate, etc. are mixed as appropriate, and if necessary, the coating properties and refraction of these resin compositions are determined. mixing the fluorine-containing acrylate or methacrylate polymer to adjust the ratio;
It is preferable to use a composition in which the photopolymerization initiator is added to this composition.

The light source used for photopolymerization is 150 to 600n111
Carbon arc lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, low-pressure mercury lamps, chemical lamps, xenon lamps, laser beams, etc. that emit light with a wavelength of 1 can be used.

[Effects of the present invention]

According to the present invention, a graded index plastic optical fiber with good flexibility can be produced continuously and efficiently, and its industrial merits are extremely large.

The present invention will be explained in more detail with reference to Examples below.

Example 1 Poly-(2,2,5,5-tetrafluoroglovir 25
°0 methacrylate)) (n, = 1.42, [η]M,,
2:26B) 60 parts, 40 parts of methyl methacrylate,
0.1 part by weight of 1-hydroxycyclohexyl phenyl ketone and 0.1 part by weight of hydroquinone were charged into cylinder 1 of the apparatus shown in Fig. 1, heated to 80C, passed through the cross section, and made into a cylinder with a diameter of 2. It was extruded as a thread through the On nozzle. At this time, the viscosity of this extrusion composition during extrusion is I
It was X I O' poise. Next, the extruded fiber was heated to 80C with nitrogen gas at +0.8/m1n.
Volatile part yf flowing at a speed of! : Pass in +5 minutes, 6
The fiber was passed through the center of a Q500W ultra-high pressure mercury lamp placed at equal intervals in a circular shape of a book, and the source was irradiated for about 0.5 minutes.
It was taken off with a nip roller at a speed of 2 o cm/m1n.

The diameter of the obtained fiber was 1000 μm, and the distribution of order refractive power was 1.441 at the center and 1.427 at the periphery, which decreased continuously from the center to the periphery. was.

The composition analysis of the obtained original fiber by NMH revealed that the center portion contained 70% by weight of BoIJ-(2,2,5,5-tetrafluoroglobyl methacrylate), and the same side portion contained 90% by weight. Ta. The overall residual content of methyl methacrylate monomer was 1.0%.

Next, 10 parts by weight of poly-(+,1,2.2-tetrahydrohebbutadecafluorodecyl acrylate), 1,
1,2,2-tetrahydrohebbutadecafluorodecyl acrylate monomer 80! f! After coating the outer periphery of the optical fiber with a die, an ultraviolet curable resin consisting of 1 part of inbutyl acrylate, 5 Nt parts of dipentaerythritol hexaacrylate, and 2 parts of 1-hydroxycyclohexylphenyl ketone, IKW immediately
A coating layer was formed by passing an ultraviolet irradiation section equipped with five high-pressure mercury lamps at a distance of 10 ports from the light source to obtain an optical fiber having a core-sheath structure with a refractive index distribution in the core.

The optical transmission loss of this original fiber is + +09 dB/Km at 590 nm and +09 dB/Km at 650 nm.
Ivy at 200 dB/Kln.

Example 2 (a) Photocurable resin forming the core component: 45 parts by weight of polymethyl methacrylate, 55 parts by weight of methyl methacrylate, 0.0 parts by weight of 1-hydroxycyclohexylphenyl ketone. I M amount # 0.1 part by weight of hydroquinone is heated to 80C, and the core component is extruded through the kneading section through the concentric compound nozzle (24) in Fig. 2.
Poly-(2,2,3,3-tetrafluorobrobylmethac25"C-ret) (n+, 40
, (η] 3.0) s.

D MEK iit part, 50 parts by weight of 2.2.3.3-tetrafluoropropyl methacrylate, 1-hydroxycyclohexylphenylketone O', I part i, hydroquinone 0
．． 1 part by weight was passed through a heated kneading section to 800 ml, and the sheath component was extruded simultaneously with the core component from the concentric composite nozzle (23) in FIG. At this time, the viscosity during extrusion is 2.5 for the core component.
X I O' Poise, sheath component is 4. It was OX I O Poise.

Next, the fiber was passed through the center of six 400W high-pressure mercury lamps installed in a circle at equal intervals, and the source was irradiated for about 5 minutes, and 2oc! It was taken off with nip rollers at a speed of n/min. The obtained fiber is a plastic fiber with a J-core-sheath structure, and the refractive index of the core component is 1.490.
, the refraction of the sheath component "JEIr!" was 1.400.The optical transmission loss of this optical fiber was 569 dB/Km at 590 nm and 6136 B/Km at 650 nm.
/ Km.

(b) After co-extruding the core and sheath components exactly as in (a) above, pass through a heat-insulating cylinder maintained at SOC for about 10 minutes before irradiating with light, and then as in (a) above. was irradiated with light to obtain a plastic original fiber having a core-sheath structure with a refractive index distribution in both the core and sheath parts. The diameter of this original fiber was 1 mm. The refractive index at the center of the core component is 1485, the refractive index near the interface with the sheath component is 1.466,
The refractive index of the sheath component near the interface with the core component was 1.425, and the refractive index of the peripheral portion was 1.405.

The optical transmission loss In of this optical fiber is 59 I dB/Km at 590 nrn, 622 dB/KIQ at 650 nm, and 2°

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing an example of a spinning device used in implementing the manufacturability of the gradient index plastic transmission fiber of the present invention, and Fig. 2 is an example of a nozzle used in the kettle for composite spinning. be. DESCRIPTION OF SYMBOLS 11... Cylinder, 12... Kneading part, 13... Heater, 14... Piston, 15... Nozzle, 16...
... Strand fiber, 17... Volatile part, 18...
・Live source line irradiation part, 19... Gas introduction hole, 20...
Nip roller, 21... Winding drum, 22... Former transmission fiber patent applicant Mitsubishi Rayon Co., Ltd. Representative Patent attorney 1) Takeshi Mura Figure 1 Figure 2

Claims (1)

[Claims] An uncured, non-volatile, transparent substance with a refractive index of n_1 and an uncured, volatile, transparent substance with a refractive index of n_2 are referred to as n_1.
A mixture selected and combined so as to maintain the relationship >n_2 with a viscosity of 10^3 to 10^6 poise is spun into a yarn, and volatile substances are volatilized from the yarn, or Or, after composite spinning using a material with a viscosity of 10^3 to 10^5 poise and a refractive index of n_1 as a core and a material with a refractive index of n_2 as a sheath, maintaining the relationship n_1>n_2,
A method for producing a gradient index plastic optical fiber, which comprises diffusing a sheath component into a core component and then curing the fiber.