JPH0451207A - Heat resistant plastic optical fiber - Google Patents

Abstract

PURPOSE:To provide the plastic optical fiber which has heat resistance and to obviate an increase in transmission loss by clouding of a sheath material by consisting a fiber material of a transparent resin having a crosslinked structure and consisting of a sheath material of a copolymer of perfluoro(2, 2- dimethyl-1, 3-dioxole) and at least one piece of other ethylenic unsatd. monomer. CONSTITUTION:The copolymer of the perfluoro(2, 2-dimethyl-1, 3-dioxole) and other monomer is a noncrystalline fluorine polymer having the transparency and low refractive index characteristic necessary as the sheath material. This copolymer has good heat resistant stability and a high glass transition temp. While the glass transition temp. is controllable as desired from about 70 deg.C to 300 deg.C by the kinds and compsn. ratios of the respective monomers constituting the copolymer, the copolymer having >=150 deg.C glass transition temp. is used.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an all-plastic optical fiber having good environmental resistance, particularly heat resistance.

[Conventional technology and issues to be solved I! J-plastic optical fibers have been recognized for their ease of end face processing, good bending resistance, and good vibration resistance, and the demand for them has been increasing recently.

This plastic optical fiber is made of polymethyl methacrylate (PMM), which has a large refractive index and good light transmittance.
The core material layer is made of a polymer such as A) or polycarbonate (hereinafter referred to as PC), and the sheath material layer is made of a transparent polymer such as a fluorine-containing polymer with a smaller refractive index than the core material layer. It is the basic structural unit.

Due to its characteristics, plastic optical fibers are suitable for use in fields such as short-distance communication sensors, and are particularly suitable for use in moving objects such as automobiles. but,
The temperature near the engine compartment of a car is 150°C.
It's getting close, PM? If an optical fiber with a core material of LA or PC is used in the engine room of an automobile, it will deform and increase transmission loss, making it practically unusable.In addition, plastic optical fiber with improved heat resistance has been developed. development was desired.

Conventionally, the main heat-resistant optical fibers have been optical fibers with a core material of PC, but also optical fibers with a core material made of cross-linked organic siloxane and a sheath material of fluorinated ethylene/fluorinated propylene copolymer. Things to do (Unexamined Japanese Patent Publication No. 1983-
175703), a core material made of a crosslinked polymer of alicyclic methacrylate and a polyfunctional monomer, and a sheath material made of a fluorinated ethylene/fluorinated propylene copolymer (Japanese Unexamined Patent Publication No. 6
3-228104), but the latter two both have a certain degree of heat resistance, but use fluorinated propylene or Teflon as a component of the fluoropolymer, and this copolymer is used as a sheath material. When used, there was an optical transmission loss due to essential cloudiness due to the crystal structure of the copolymer in the sheath material, and the transmission loss was large.

[Means for Solving the Problems] Therefore, the present inventors completed the present invention as a result of intensive studies to develop an all-plastic optical fiber that has sufficient heat resistance and does not cause increased transmission loss due to clouding of the sheath material. The gist is that the core material is made of a transparent resin with a crosslinked structure, and the sheath material is made of perfluoro(2,2-dimethyl-1,3-dioxole) and at least one other ethylene-based material. The all-plastic optical fiber has a core-sheath structure made of a copolymer with an unsaturated monomer.

The core material of the plastic optical fiber used in carrying out the present invention is one that can form a transparent crosslinked polymer obtained by polymerizing monomers that can be crosslinked by heat or light. As the monomer, a monofunctional monomer, a mixture of polyfunctional monomers, or a single polyfunctional monomer is used, and the monofunctional monomers include methyl (meth)acrylate and ethyl (meth)acrylate. , alkyl (meth)acrylates such as propyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate,
(Meth)acrylates having an ester group with a ring structure such as cyclohexyl (meth)acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, bornyl (meth)acrylate, isobornyl (meth)acrylate, and adamantyl (meth)acrylate; (Meth)acrylates with fluorinated ester groups such as trifluoroethyl (meth)acrylate, styrene, 0-chlorostyrene, α~methylstyrene, p-
Styrene derivatives such as chlorostyrene and siloxane derivatives having a vinyl group can also be used, but are not limited to these.

As a polyfunctional monomer, ethylene glycol di(meth)
Acrylate, diethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, hexanediol(meth)acrylate, dipentaerythritol poly(meth)acrylate, -divinylbenzene, etc., or these Examples include mixtures and siloxane derivatives having two or more vinyl groups, but are not limited thereto.

The sheath material of the plastic optical fiber used in the present invention is a copolymer of perfluoro-(2,2-dimethyl-1,3=dioxole) and at least one other ethylenically unsaturated monomer. .

Perfluoro-(2,2-dimethyl-1,3-dioxole) used in the present invention is disclosed in, for example, US Pat.
It can be synthesized by the method described in No. 845. Further, the copolymer is disclosed in US Pat. No. 3,978, for example.
It can be produced by the method described in No. 030.

Examples of the ethylenically unsaturated monomer include ethylene, propylene, isobutylene, butene-11 methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, and the like.

In addition, the following fluoroolefins are used as fluoroethylene compounds such as Ch=CFt, CHF=
Ch, C1l z = CP z, CH,=CHF.

CC1=CFz, CHCI-CFz, CCI!壬cps
,C(JP-CCIP.

CUP = CCI,, CHx = CCjPSC(Jz”
=C (JP, etc., fluoropropylene compounds such as CF
sCF'''Ch, ChCF=CHF%CFsCFl=C
Ft, CFxCH””CHz.

CHsCF”CFx, CHzCtl=CFt, CHsC
F = Hz.

CICC1=CC1, CFsCC! =cFx, ChCF
”=CFCZ.

CICC1=Ch, CFtCICF=CFCI, CF
(JzCF=Ch, CICC1=CCIF, CF20
CI=CC1z, CICC1=CC1z, CC et al CF
= CFz, CF, CICC1=CC1,, cpczz
cci=cci,, CICC=CC1, CCjFzCF
=CHIJ, CFiCCZ=CHC4゜CICC1=
CCb, CF2CI=CC1z, CF tclccl
= CHCl, CCI, CF=CHC1, CFzjCF
==Ch, CFJrCH=Ch.

CF2CBr=CHBr, Ch(JCBr=CHt,
CHzBrCF=CC1z, CPsCBr=CHz,
CFsCH=CHBr, ChBrCIl=CHF.

Fluoroolefin compounds having 4 or more carbon atoms, such as CFJrCF=Ch, etc., such as CFsChCF=CFz, CI
CC=CC1, CF2CI=CC1z, CFz=
CFCF zcHF z, CFsCFxCF=CHtS
CFsCH=CHCFs, CFt=CFCFtCHs,
CFg=CFCHzCH3, CFsCHzCH=Ctl
z, CFzCfl=CHCth, Ch=CHCHzCH
s, CHtChCH=CHx, CFHzCH=CHCF
Hz, CHsCFtCH=Ctlz, CHz=CPCH
zCHs, CF s (CF z) gcP = CF
t, CFs (CFt) scF=cPt, etc.

Furthermore, monomers having functional groups such as perfluoro(alkyl vinyl ether), methyl-3-(1-(difluoro[(trifluoroethynyl)oxycomethyl)-1,
2,2,2-tetrafluoroethoxy)-2,2,3,
3-tetrafluoropropanoate, 2-(1-[difluoro[(trifluoroethynyl)oxycomethyl)]
-1,2゜2.2-tetrafluoroethoxy) -1
, 1,2,2-tetrafluoroethanesulfonyl fluoride, etc. can be used.

The copolymer of perfluoro-(2,2-dimethyl-1,3-dioxole) and the above-mentioned other monomers is a non-grade fluorine having the transparency and low refractive index required for the sheath material. It is a type polymer. Furthermore, since it has a perfluoro-(2,2-dimethyl-1,3-dioxole) ring structure in the polymer, it has good heat resistance stability and exhibits a high glass transition temperature.

The glass transition temperature of the copolymer varies from about 70°C to 300°C depending on the type and composition ratio of each monomer that makes up the copolymer.
In the present invention, it is preferable to use a glass transition temperature of 130° C. or higher, particularly 150° C. or higher.

Conventionally, fluorinated ethylene/fluorinated propylene copolymers have been used as sheath materials for heat-resistant plastic optical fibers whose core materials are made of transparent resins with a crosslinked structure due to their heat resistance and low refractive index. It was getting worse. However, this fluoropolymer is a crystalline polymer having a melting point of 280 to 290°C, and is essentially a cloudy polymer with extremely low transparency. When optical fibers using this polymer as a sheath material undergo total reflection of light at the core-cord interface, the amount of transmitted light decreases significantly due to diffuse reflection of light on the surface of the sheath material, which impedes the light transmission performance of the core material. It is something. On the other hand, the optical fiber developed in the present invention has a completely non-quality sheath material and has sufficient low refractive index and heat resistance. It is something.

The method for manufacturing the optical fiber of the present invention is not particularly limited, but perfluoro(2,2-dimethyl-1,3
- A hollow tube made of a copolymer of (dioxole) and at least one other ethylenically unsaturated monomer is prepared, and an unpolymerized core material is filled into the tube and polymerized to form a plastic optical fiber. After forming the core fiber, a solution containing a copolymer of perfluoro(2,2-dimethyl-1,3-dioxole) and at least one other ethylenically unsaturated monomer is dissolved. It is preferable to use a method in which an optical fiber is created by coating the circumference of a core fiber and drying it.

The present invention will be explained in more detail below using Examples.

Example 1 Methyl methacrylate 80-1%, ethylene glycol dimethacrylate 19-1%, 2,2°-azobis(2
, 4,4-)limethylpentane) was stirred and mixed in a pressurized tank to obtain a precursor for forming a core material.

70/30 mo1% of perfluoro(2,2-dimethyl-1,3-dioxole) and tetrafluoroethylene
A hollow tube of the copolymer was prepared at an extrusion temperature of 240°C, placed in a hot air dryer at 135°C, and the core material forming precursor was fed from the end face with nitrogen pressure, and the tube remained in the hot air dryer. The polymerization was carried out by heating for 3 hours to obtain an optical fiber.

The optical transmission loss of the obtained optical fiber was 214 dB/b+
(650r++w), and the optical transmission loss after heating at 150℃ for 1000 hours is 240dB/Km (650n■
) and had excellent heat resistance.

Examples 2 to 4 Optical fibers were produced in the same manner as in Example 1, except that the composition of the precursor for forming the core material was changed as shown in Table 1. The evaluation results are shown in Table-1.

Comparative Example 1 Using a core material precursor having the same composition as that used in Example 1,
An optical fiber was produced in the same manner as in Example 1 except that the sheath material was changed to a tube made of tetrafluoroethylene/fluorinated propylene copolymer.

The evaluation results are shown in Table-1.

Example 5 A 1:1 mixture of ph ph (in the formula, Pb: phenyl group, Me: methyl group, vi: vinyl group) was filtered through a polytetrafluoroethylene filter with a pore size of 0.1-. 95.0 parts of PhSi + 5.0 parts of Phztl)s and 5/1 chloroplatinic acid dissolved in 2-ethylhexanol.
00 parts were each filtered through a polytetrafluoroethylene filter with a pore size of 0.1-, and mixed and defoamed in a clean room to prepare a precursor for forming a core component.

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

Refractive index I'161.51, tensile strength 2 kg/cgl
, the elongation was 60%.

PDD/TFE created in Example 1 = 70/
A hollow tube of 30 mo 1% copolymer is placed in a hot air dryer at 150°C, and the core component forming precursor is fed from the end face with nitrogen pressure, heated and polymerized for 1 hour in the hot air dryer to form an optical fiber. I got it.

The optical transmission loss of the obtained optical fiber was 350 dB/Km.
(650 nm).

Example 6 A mixture of 75e+t% of methyl methacrylate, lht% of tetraethylene glycol dimethacrylate, and 5 wt% of benzyl methyl ketal was stirred and mixed in a pressurized tank to prepare a precursor for forming a core material.

PDD/TFE created in Example 1 = 70
/ 3 (1wo1% copolymer hollow tube 8 (E
/am, and was placed in an ultraviolet irradiation furnace with an effective length of 300 I, and the core material forming precursor was fed from the end face under nitrogen pressure and polymerized for 10 minutes in the furnace to obtain an optical fiber.

The optical transmission loss of the obtained optical fiber was 305 dB/K
It was a+ (650n■).

Comparative Example 2 An optical fiber was obtained in the same manner as in Example 6 except that the hollow tube in Example 6 was changed to a tetrafluoroethylene/fluorinated propylene copolymer tube. However, due to the opacity of the sheath material tube, The core material forming precursor could not be sufficiently irradiated with ultraviolet rays, and the core material was not polymerized.

(Residual monomer 38-1%)

Claims (1)

[Claims] 1) The core material is made of a transparent resin having a crosslinked structure, and the sheath material is a copolymer of perfluoro(2,2-dimethyl-1,3-dioxole) and at least one other ethylenically unsaturated monomer. An all-plastic optical fiber with a core-sheath structure.