JPH02228610A - Plastic optical fiber - Google Patents

Abstract

PURPOSE:To obtain the plastic optical fiber having particularly excellent heat resistance by forming a core of a crosslinkable resin which is substantially constituted of a specific monomer. CONSTITUTION:The crosslinkable resin substantially constituted of the monomer optical fiber expressed by formula I where R denotes 1 to 10C org. group and X is F, Cl, Br is used for the core. The resin for the core material is essentially required to be the crosslinkable resin in order to improve heat resistance. The chief material of the core material is required to be crosslinked by copolymerizing a multifunctional monomer as an auxiliary component in the case of using a monofunctional monomer as the above-mentioned chief material. The addition of a stabilizer, such as antioxidant, into the monomer at the time of polymn. is possible in order to improve the heat resistance. The well balanced plastic optical fiber is obtd. by using fluoroplastic resin having the excellent heat resistance and low refractive index for the clad material. The plastic optical fiber which can maintain >=90% holding rate of light quantity for >=1,000 hours in the air of 150 deg.C and has the excellent heat resistance is obtd. in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a plastic optical fiber, and particularly to a plastic optical fiber with excellent heat resistance.

[Conventional technology]

Most plastic optical fibers use linear polymers, such as polymethyl methacrylate, as the core material resin, because they can be easily made into wires and can be prevented from melting. However, these plastic optical fibers deform when heated to a temperature of 100° C. or higher and lack heat resistance, so they cannot be installed near a heat generating element such as an automobile engine. In order to improve this, as described in JP-A-57-45502 or JP-A-62-25706, a tube-shaped cladding material is filled with a crosslinking monomer.1. A plastic optical fiber has been proposed whose core portion is made of a crosslinkable resin that has been polymerized by heating.

Further, for the purpose of increasing heat resistance by improving the cladding material, as described in JP-A-63-127205.

A plastic optical fiber using a resin containing α-chloroacrylate as a cladding material has been proposed.

[Problem to be solved by the invention]

Among the conventional technologies mentioned above, plastic optical fibers using cross-linked resin as the core material are effective in improving short-term heat resistance, but are required for use in engine rooms of automobiles etc. 10 at a high temperature of 125-135℃
When used for a long time of 00 hours or more, there was a problem in that the resin became significantly colored and deteriorated to the point where it was difficult to transmit light.

In addition, plastic optical fibers using resin containing α-chloroacrylate as the cladding material can withstand use for more than 1000 hours at temperatures below 120'C, but since this resin is basically a linear polymer, There was a problem that depolymerization occurs at high temperatures, deforming the optical fiber, and making it unusable.

It is an object of the present invention to provide a plastic optical fiber made of a resin with excellent heat resistance that exhibits little discoloration even when used for more than 1000 hours at a high temperature of 150° C., in which both the core and cladding have well-balanced heat resistance. There is a particular thing.

[Means to solve the problem]

For the above purpose, when R represents an organic group having 1 to 10 carbon atoms and X is F, Cg, or Br, the core is essentially composed of a heptad group represented by CHz = C-X oo-R. This is achieved by using a crosslinkable resin composed of:

Here, if the content of this component is 55% by weight or less, heat resistance will not be maintained sufficiently.

In the present invention, it is essential that the core material resin be a crosslinkable resin in order to improve heat resistance.

When a monofunctional motumar is used as the main ingredient of the core material, it is necessary to copolymerize and crosslink a polyfunctional motumar as a subcomponent. When a polyfunctional monomer is used as the main ingredient, it may be used either as the - component alone or as a copolymer with other monomers.

Furthermore, in order to improve heat resistance, it is also possible to add a stabilizer such as an antioxidant to the hexamer during polymerization.

In addition, the heat resistance of the cladding material also has a large effect on the heat resistance of plastic optical fibers. It becomes possible to obtain plastic optical fibers.

[Function] In the present invention, R of the monomer represented by these is a methyl group, an ethyl group, a propyl group, an isopropyl group, or a butyl group.

tart-butyl group, cyclohexyl group, allyl group, glycidyl group, adamantyl group, tricyclodecyl group, phenyl group, benzyl group, or a fluorine-containing alcohol residue having 2 to 5 carbon atoms, a chlorine-containing alcohol residue, or a bromine-containing alcohol Examples include residues. Furthermore, as an example of R, +CHz→TOCCR'=CHz -(2)
where, n; integer R' from 1 to 6; H, CHa or F, Cl, Br, or +c Hzo-++I-CCR"= CHz
・= (3) ■ Here, n ; an integer from 1 to 6 R'': a group in which the monomer of formula (1) represented by H, CH3 or F, Cl, or Br becomes a bifunctional monomer or trimethylolpropane (α-fluoroacrylate), trimethylolpropane tri(α-chloroacrylate), and trimethylolpropane tri(α-bromoacrylate).

Polymerization initiators used in the polymerization of the core material include 3,5゜5-trimethylhexanoyl peroxide, lauroyl peroxide, benzoyl peroxide, and 1,1-bis(t-butylperoxy) 3゜3.5- Peroxide-based radical initiators such as trimethylcyclohexane, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxybenzoate, dicumyl peroxide, di-t-butyl peroxide, etc. Can be used.

The antioxidant used to improve heat resistance is not particularly limited, and known antioxidants are used.

Suitable examples of the antioxidant include hindered phenol, phosphanite, and thioether compounds.

The amounts of the polymerization initiator and antioxidant contribute to the heat resistance and photoconductivity of the resulting optical fiber, and are determined from the balance of the molding temperature and the composition. Molding temperature is 50-150℃
The polymerization initiator is 0.01 to 5% by weight of the total amount of seven polymers,
It is preferable to use the antioxidant in an amount of 0 to 5% by weight; if the amount is more or less than this, the heat resistance and light transmission properties of the resulting optical fiber will deteriorate.

From the viewpoint of heat resistance, the cladding material of the plastic optical fiber in the present invention is preferably a fluorine-containing olefin resin. Particularly suitable resins include:
Polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-ethylene copolymer (ETFE) ), polytrifluorochloroethylene (PC
TFE), Boria”/Vinyrizo:,/ (PVdF)
etc.

The plastic optical fiber of the present invention can be manufactured by a conventionally known method.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to FIGS. 1 to 4.

Fig. 1 is a structural diagram showing an embodiment of the plastic optical fiber of the present invention, Fig. 2 is an explanatory diagram of a manufacturing apparatus using the tube filling method for the plastic optical fiber of the present invention, and Fig. 3 is a structural diagram showing an embodiment of the plastic optical fiber of the present invention. FIG. 4 is an explanatory diagram of a core material manufacturing apparatus, and FIG. 4 is an explanatory diagram showing an optical sensor for a tachometer using the plastic optical fiber of the present invention.
b) is a side view.

As shown in FIG. 1, the plastic optical fiber optics of the present invention comprises a cladding 1 made of a fluorine-containing olefin resin and a core 2 made of a crosslinkable halogenated acrylate resin. In the example shown in FIG. 1, various characteristics of the optical fiber were measured by the following methods.

Transmission loss> Evaluation of optical transmission performance is performed by measuring the amount of transmitted light Pr (nW) of an optical fiber of length Li (m) in the wavelength region of 450 to 850 nm, cutting it to a length Lz (m), and measuring this length. Sashi 2. A cutback method was used in which the transmitted light amount Pz (nW) of the optical fiber was measured and the transmission loss was calculated from the difference.

Transmission loss α (dB/m) is determined by the following formula.

From this equation, it can be seen that the smaller the α value, the better the optical transmission performance.

Heat resistance> Heat resistance is evaluated using 1 method, which is close to the actual usage conditions.
This was carried out using a 50'C air constant temperature bath. In this, length 2
An evaluation sample of an optical fiber of m was heated, and after 1000 hours, it was taken out and the transmission loss was measured. Acrylate plastic optical fibers often use LEDs with a wavelength of 660 nm as a light source, so the heat resistance evaluation is based on wavelength 660 nm.
A comparison was made based on the light intensity retention rate at 60 nm. Light intensity retention rate K
(%) is the transmission loss before heating at a wavelength of 660 nm, αo (d B/m), and the transmission loss after heating, α1 (d B/m).
B/m), it is determined by the following formula.

Example 1 (tube filling method) Methyl-α-bromoacrylate 75g, methyl methacrylate 5g, ethylene gelcol dimethacrylate 2
0g, add 0.5g of benzoyl peroxide as a polymerization initiator to the monomer to prepare a core material sample,
The zero-thickness injected into the 7-mer tank 5 shown in FIG. After connecting the Onm resin tube 3 to the monomer tank 5, a core material sample was injected from the monomer tank 5 into the resin tube 3 to fill it. After sealing the other end of the resin tube 3, the resin tube 3 is passed through a guide roll 6 and wound up with a take-up roll 7, so that the heating part of the resin tube 3 is sequentially moved in an oil bath 4 at a speed of ioam/min. Polymerizes at 90°C with a length of 20
A plastic optical fiber 8 having a length of m was obtained. A heat resistance test was conducted by heating the obtained plastic optical fiber at 150° C. for 1000 hours. The initial transmission loss at wavelength 66Qnm is 1.1 dB/m, and the transmission loss after heating is 1.5
It was dB/m. The light intensity retention rate of this optical fiber is 91
%, and the heat resistance was extremely excellent.

Comparative Example 1 Using a mixing pot consisting of 80 g of methyl methacrylate and 20 g of ethylene glycol dimethacrylate, a plastic optical fiber was obtained in the same manner as in Example 1, and a heat resistance test was conducted in the same manner as in Example 1. Wavelength 660n
The initial transmission loss at m was 0.9 dB/m, and the transmission loss after heating was 8.7 dB/m. The light intensity retention rate of this optical fiber was 16%, and it had deteriorated to the point where it could hardly transmit light.

Example 2 (heat shrink tube method) 75 g of methyl-α-chloroacrylate, 5 g of methyl methacrylate, 20 g of ethylene glycol diacrylate
A core material sample was prepared by adding 0.5 g of benzoyl peroxide as a polymerization initiator to a mixed monomer consisting of Inner diameter 1.
5++n into a stainless steel tube 11 with a length of 1 m, and was polymerized in the tube at 55°C by a heater 12 for gel preparation.
It was extruded at a rate of 1 mm/min under nitrogen pressure of about 5 kgf/- to form a gel-like core-shaped product 14 with a conversion rate of about 30%. This gel-like core-shaped material 14 was polymerized at 90.degree. C. by a curing heater 13 outside the tube to obtain a core material resin 15 having a diameter of 1.5 square centimeters. Core material resin 15 is taken up in one roll 1
It is wound up at 6. Additionally, the manufacturing equipment is covered with a heat insulating material 17 to control the temperature. This was covered with a polytetrafluoroethylene (PTFE) heat-shrinkable tube with an inner diameter of 2.0 mm, and heated to 150° with a hot air gun.
A plastic optical fiber having a length of 8 m was obtained by successively heating and coating at .degree. When this optical fiber was subjected to the same heat resistance test as in Example 1, the initial transmission loss at a wavelength of 660 nm was 1.1 dB/m, and the transmission loss after heating was 1.7 dB/m.
dB/m.

Further, the light amount retention rate was as good as 87%.

Comparative Example 2 A plastic optical fiber was obtained in the same manner as in Example 2 using a mixing pot consisting of 80 g of methyl methacrylate and 20 g of ethylene glycol diacrylate. When the same heat resistance test as in Example 1 was conducted, the initial transmission loss at a wavelength of 660 nm was 1.0 dB/m, and the transmission loss after heating was 9.2 d 87 m. Light intensity retention rate is 15%
, and could not transmit light.

Example 3 (Addition of antioxidant) In Example 1, the mixed monomer before polymerization was used as an antioxidant and tris-(3,5-di-t-butyl-4-hydroxybenzyl)-isocyanate was added in a total monomer amount of 100.
A plastic optical fiber was obtained in the same manner.

When we conducted a heat resistance test, the initial transmission loss at a wavelength of 660 nm was 1.3 dB/m, and the transmission loss after heating was 1.4.
It was dB/m. Therefore, an extremely excellent light amount retention rate of 98% was obtained.

Examples 4 to 18 Plastic optical fibers were produced using the same monomer compositions and clad materials as in Examples 4 to 18, using the same method as in Example 1 to fill and mold the core monomer into the tubular clad material. The measurement results of transmission loss and heat resistance evaluation are shown in Tables 1 to 3. Here, the heat resistance is 150℃.
The light intensity retention rate at a wavelength of 660 nm after heating for 1000 hours at a wavelength of 660 nm, and the transmission loss showed the initial measured value at a wavelength of 660 nm.

Examples 19 to 23 Plastic optical fibers were produced using the same monomer compositions and cladding materials as in Examples 19 to 23 using a heat-shrinkable tube for cladding in the same manner as in Example 2.

Table 4 shows the measurement results for transmission loss and heat resistance evaluation.

Note that the heat resistance here is the light intensity retention rate at a wavelength of 660 nm after heating at 150° C. for 1000 hours, and the transmission loss is the initial measured value at a wavelength of 660 nm.

Comparative Example 3 0.5 g of benzoyl peroxide was added to 100 g of methyl-α-chloroacrylate monomer, and a plastic optical fiber whose core polymer was not a crosslinked resin was obtained in the same manner as in Example 1, and the heat resistance test was conducted in the same manner as in Example 1. After heating at 150° C. for 100 hours, the core polymer had already evaporated, leaving only the PFA tube.

FIG. 4 shows an example in which the plastic optical fiber of the present invention is used as an optical sensor component for a tachometer. A disk 19 is fixed to the shaft 18 of the device whose rotation is to be measured or controlled, and a slit 20 is provided around the disk 19.
An optical component consisting of a photodiode 21 and an optical fiber 22, and an optical component consisting of a photodiode 23 and an optical fiber 22 are each fixed at their tips to a jig 24, and the light emitted from the LED 21 is provided on a disk 19 by rotation of the shaft 18. The light is incident on the photodiode 23 through the slit 20 .

The number of revolutions can be measured by the counter 25 from the pulses of light incident on the photodiode 23, and is displayed on the display section 26. As a result, it becomes possible to control the number of revolutions per rotation.

The measurement and control of the rotational speed described above can be similarly applied to a reflective type in which a reflective portion is provided in place of the slit 20 on the disc 19 and the reflected light is incident on the photodiode 23.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to obtain a plastic optical fiber that can maintain a light intensity retention rate of 90% or more for 1000 hours or more in air at 150°C and has extremely excellent heat resistance. .

[Brief explanation of the drawing]

Fig. 1 is a structural diagram showing an embodiment of the plastic optical fiber of the present invention, Fig. 2 is an explanatory diagram of a manufacturing apparatus using the tube filling method for the plastic optical fiber of the present invention, and Fig. 3 is a structural diagram showing an embodiment of the plastic optical fiber of the present invention. FIG. 4 is an explanatory diagram of a core material manufacturing apparatus, and is a general view and a side view showing a tachometer sensor using the plastic optical fiber of the present invention. 1... Fluorine-containing olefin resin cladding, 2...
・Crosslinkable halogenated acrylate resin core, 3.
...Resin tube, 4...Oil bath, S...Dry tank, 8...Plastic optical fiber, 9...
・Core material sample, 10... Monomer tank, 11...
Stainless steel tube, 12... Heater for gel production, 13...
・Curing heater, 14... Gel-like core-shaped object, 15.
...Resin for core material, 16... Winding roll. ■ False Suction 7 Tower 4 (b)

Claims (1)

[Claims] 1. In a plastic optical fiber composed of a core and a cladding, R represents an organic group having 1 to 10 carbon atoms;
A plastic optical fiber characterized in that, when X is F, Cl, or Br, the core is a crosslinkable resin essentially consisting of a monomer represented by the following formula. 2. The plastic optical fiber according to claim 1, wherein the core contains 0.01 to 5% by weight of an antioxidant. 3. The plastic optical fiber according to claim 1, characterized in that a fluororesin is used as the cladding material. 4. In a plastic optical fiber composed of a core and a cladding, R represents an organic group having 1 to 10 carbon atoms,
When X is F, Cl, or Br, the core is made of a crosslinkable resin essentially consisting of the monomer represented by The polymerizable monomer for the core material is filled in a hollow cladding material, and the core material is sequentially moved and polymerized from one end under polymerization conditions to form a core part, resulting in an integrated core-cladding structure. plastic optical fiber. 5. In a plastic optical fiber composed of a core and a cladding, R represents an organic group having 1 to 10 carbon atoms,
When X is F, Cl, or Br, the core is made of a crosslinkable resin essentially consisting of a monomer represented by ▲There are mathematical formulas, chemical formulas, tables, etc.▼ The material is introduced into a tube, gradually polymerized inside the tube and extruded under pressure to form a gel-like core, and the polymerization is completed outside the tube to form the core, which is then covered with a clad resin. and plastic optical fiber. 6. Claim 1 used as optical sensor component
5. The plastic optical fiber according to item 4 or 5.