JPH01306806A - Plastic optical fiber - Google Patents

Abstract

PURPOSE:To improve light transmission performance and heat resistance by forming a sheath component of a UV curing type polymer which has the refractive index lower than the refractive index of a fiber component polymer and contains an antioxidant and covering the outside layer of the optical fiber with an UV curing resin contg. the antioxidant. CONSTITUTION:The sheath component is formed of the UV curing type polymer which has the refractive index lower than the refractive index of the fiber component polymer and contains the antioxidant and the outside layer of the optical fiber is coated with the UV curing type resin contg. the anitoxidant. The fiber component is exemplified by transparent plastic materials such as, for example, polymethyl methacrylate resin, polystyrene resin, deuterated polymethyl methacrylate, and styrene. A compd. having radical polymerizable double bonds, etc., are included as the compd. for production of the UV curing type polymer to be used as the sheath component. The light transmission performance and heat resistance of the optical fiber cord are improved in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a plastic optical fiber used for optical fiber cords, optical fiber cables, and the like.

[Conventional technology]

Plastic optical fibers use a highly transparent polymer such as polymethyl methacrylate or polystyrene as the core material, and a polymer with a lower refractive index than the core material as the sheath material.The core material and sheath material, which are thermoplastic resins, are molten. It is manufactured by a composite spinning method that forms a core-sheath structure. However, the usable temperature of plastic optical fibers is low; for example, when polymethyl methacrylate and polystyrene are heated at temperatures above 80°C, and when polycarbonate is heated at temperatures above 120°C for a long period of time, the transmission performance deteriorates rapidly, making them practically unusable. It is known that this is not possible.

JP-A No. 60-194413 discloses that the outer layer of a plastic optical fiber is coated with an ultraviolet curable resin having a shore D hardness of 65 or more, and then the resin is cured by irradiating ultraviolet rays to achieve heat resistance and moisture heat resistance. It is described that an improved plastic optical fiber is obtained.

Although this plastic optical fiber can prevent shrinkage of the strands due to heating by using an ultraviolet curable resin, it cannot prevent reduction in transmission performance due to heating.

Furthermore, in JP-A-62-192702, the outer layer of a plastic optical fiber wire having a sheath material made of an ultraviolet curable resin is made of a resin having a Vicat softening temperature higher than the glass transition temperature of the core material polymer. Coated plastic optical fibers are described.

This optical fiber is said to have heat resistance close to the glass transition temperature of the core material. However, the sheath material is an ultraviolet curable resin that forms a crosslinked structure after curing.
Although there is no melt shape deformation due to heating, in a high temperature environment of 125°C or higher, thermal deterioration of the sheath material polymer occurs,
As mechanical strength decreases and discoloration progresses,
Actually, it does not have long-term heat resistance. Furthermore, in order to obtain optical fibers that are heat resistant at high temperatures, when a core material with a high glass transition temperature is used, it is coated with a resin that has a Vicat softening temperature higher than the glass transition temperature, so a higher molding temperature is required. There is a problem in that the optical fiber is damaged by heating during coating molding, resulting in a decrease in optical transmission performance.

[Means for Solving the Problem] The present invention provides a core-sheath type plastic optical fiber in which the sheath component is formed from an ultraviolet curable polymer having a lower refractive index than the core component polymer and containing an antioxidant. This is a plastic optical fiber in which the outer layer of the optical fiber is coated with an ultraviolet curable resin containing an antioxidant.

Core components used in the plastic optical fiber of the present invention include, for example, polymethyl methacrylate resin, polystyrene resin, polycarbonate resin, poly-4
- Transparent plastic materials such as methylpentene-1, deuterated polymethyl methacrylate and styrene.

As the sheath component, an ultraviolet curable polymer having a lower refractive index than the core component and containing an antioxidant is used. Compounds for producing ultraviolet curable polymers include compounds having radically polymerizable double bonds, such as unsaturated polyesters, polyester acrylates, urethane acrylates, epoxy acrylates, polyethers,
Unsaturated polybutadiene type, melamine acrylate type compound, monofunctional or polyfunctional acrylate, general formula % formula % (in the formula or hydrogen atom or fluorine atom, Y is a hydrogen atom, fluorine atom or methyl group, m is an integer of 1 to 5 , n is an integer of 1 to 10).

formula! Or, as the compound (2), for example, the following compounds are used. 2,2-difluoroethyl (meth)acrylate, 2,2.2-trifluoroethyl (meth)acrylate, 2,2,3.3-tetrafluoropropyl (meth)acryle), 2,2゜3,! 1,3-pentafluoropropyl (meth)acrylate, 2,2,3,3,4
, 4-hexafluorobutyl (meth)acrylate, 1
-Trifluoromethyl-2,2,2-trifluoroethyl (meth)acrylate, 2,2,3,3,4,4,5
, 5-octafluoropentyl (meth)acrylate,
1,1-di-trifluoromethyl-2,2,2-trifluoroethyl (meth)acrylate, 2,2,3,3,
4,4,5,5゜6.6,7.7-dozocafluoroheptyl (meth)acrylate, 3,3,4,4,5,5,
6,6,7,7,8,8.8-) lisdecafluorooctyl (meth)acrylate, 3,3,4,4,5,5,
6,6,7,7,8,8,9,9,10,10,10-
Hebutadecafluorodecanyl (meth)acrylate, α
-Fluoro-2,2,2-trifluoroethyl acrylate, α-fluoro-2,2,3,3-tetrafluoropropyl acrylate, α-fluoro-2,2,3,3
, 3-pentafluoropropyl acrylate, α-fluoro-1-trifluoromethyl-2,2,2-)lifluoropropyl acrylate, α-fluoro-2-)!
j Fluoromethyl-2.3.3.3-tetrafluoropropyl acrylate, α-fluoro-2,2,3,4,
4,4-hexafluorobutyl acrylate, α-fluoro-1-methyl-2,2,3,4,4,4-hexafluorobutyl acrylate, α-fluoro-1,1,2
, 2-tetrahydroperfluorodecyl acrylate,
α-Fluoro-1,1,2,2-tetrahydro-9-trifluoromethylperfluorodecyl acrylate, α
-fluoro-1,1-dihydroperfluorobutyl acrylate, α-fluoro-1,1-dimethyl-2,2,
! l, 3-tetrafluorofurohyl acrylate, α
-Fluoro-1,1-dimethyl-2,2,3,3,4,
4,5,5-octafluoropentyl acrylate, α
-Fluoro-1,1-dimethyl-2,2,3,4,4,
4-hexafluorobutyl acrylate, etc. In addition, α-fluoromethyl acrylate, α-fluoroethyl acrylate, etc. can also be used. In order to obtain a low refractive index, it is preferable to introduce fluorine atoms into the structure of the compound.

The ultraviolet curable polymer needs to contain an antioxidant. In general, UV-curable polymers tend to undergo oxidative deterioration at high temperatures of 125 degrees Celsius or higher (coloring occurs, which leads to a decrease in the transparency required as a sheath material, and the optical transmission performance of the optical fiber decreases. It is difficult to use it at high temperatures for a long period of time.This deterioration due to heat can be prevented by introducing an antioxidant, making it possible to maintain the transparency required as a sheath component.

As the antioxidant, for example, phosphite compounds such as hindered phenol, thioether, alkyl phosphite, allyl phosphite, and alkylaryl phosphite can be used. Hindered phenol compounds that are effective in preventing radical decomposition deterioration are preferred.

Antioxidant content is 0.0 relative to UV curable polymer
1 to 10% by weight, particularly 0.1 to 5% by weight, is preferred. When the content of the antioxidant is less than 0.01% by weight, the effect on heat resistance is poor, and when it is more than 10% by weight, the transparency of the sheath material decreases.

Examples of photopolymerization initiators include benzoin-based, azo-based, diphenyl sulfide-based, organic peroxide-based, organic dye-based, and iron phthalocyanine-based compounds.

The optical fiber of the present invention has a core-sheath structure whose outer layer is coated with an ultraviolet curable resin.

Since this coating resin is UV-curable, there is less thermal damage during the resin coating process (there is no reduction in optical transmission performance) compared to when thermoplastic resin is used.The coating resin is similar to the sheath material. In order to prevent thermal deterioration in high-temperature environments, it is necessary to contain antioxidants.

The type of ultraviolet curable resin and antioxidant used as the coating resin may be the same as the ultraviolet curable polymer and antioxidant used as the sheath component.

In order to produce the optical fiber of the present invention, instead of using core-sheath composite spinning, a fiber consisting of a core component alone is first created, and then a compound for producing an ultraviolet curable polymer, an antioxidant, and a light source are added to the surface of this core component. After applying a sheath material composition containing a polymerization initiator, it is cured by irradiation with ultraviolet rays using a high-pressure mercury lamp, fluorescent chemical lamp, etc. to obtain an optical fiber having a core-sheath structure. The compound having a radically polymerizable double bond, which is the main component of the sheath material composition, may be either a monomer or a polymer, or may be a mixture thereof. The desired optical fiber code can be obtained by forming an ultraviolet curable coating resin layer on the outer layer of this optical fiber by the same operation as in forming the sheath material layer.

The optical fiber bar code thus obtained has heat resistance for a long period of time even at high temperatures, and has extremely good initial optical transmission performance.

The optical transmission loss in the following side was measured using the method described in JP-A-58-7602. Measurement wavelength is 770nm
, fiber-input light with a numerical aperture of 0.6 was used.

Example 1 50 parts by weight of trifluoroethyl acrylate, 35 parts by weight of tertiary butyl acrylate, 5 parts by weight of glycidyl acrylate
Parts by weight, trimethylolpropane triacrylate 10
parts by weight, 4 parts by weight of benzyl dimethyl ketal (Irgacure 651 manufactured by Ciba Geigy) as a photopolymerization initiator, and triethylene glycol-bis[6-(
0.75 parts by weight of 6-tert-butyl-5-methyl-4-hydroxyphenyl)propionate (Irganox 245, manufactured by Ciba Geigy) were mixed at room temperature to obtain an ultraviolet curable resin composition.

After applying the above ultraviolet curable resin composition to the outer layer of a polycarbonate core fiber made of bisphenol A with an outer diameter of 980 μm, it was irradiated with an irradiation energy of 80 W/crn using an ultraviolet irradiation device with a built-in high-pressure mercury lamp. An optical fiber having a core-sheath structure with an outer diameter of 1000 μm was obtained.

The optical transmission loss of this optical fiber was 955 dB/km at a wavelength of 770 nm.

Furthermore, 90 parts by weight of urethane acrylate resin (Aloex M-1200 manufactured by Toagosei Kagaku Kogyo Co., Ltd.), 10 parts by weight of acrylate (NK ester A-200 manufactured by Shin-Nakamura Chemical Industry Co., Ltd.) with polyethylene glycol di as a crosslinking agent, and photopolymerization started. 4 parts by weight of benzyl dimethyl ketal as an agent and octadecyl-3-(3,5-
Ditert-butyl-4-hydroxyphenyl) flobionate (Irganox 1076 manufactured by Ciba Geigy) 1.0
A photocurable resin composition consisting of parts by weight was applied to the outer layer of the optical fiber, and then a coating resin layer was formed by irradiation with ultraviolet rays to obtain an optical fiber bar code. The optical transmission loss of this optical fiber barcode was 955 dB/km at a wavelength of 770 nm, and there was no performance deterioration during the coating process. This optical fiber barcode was heat-treated at 125° C. for 4000 hours. As a result, there was no change in the appearance of the optical fiber barcode, and the optical transmission loss was reduced at a wavelength of 770 nm.
It was 1020 dB/km, indicating good heat resistance.

Examples 2 to 4 Optical fiber barcodes were obtained in the same manner as in Example 1 except that the compositions of the core component and sheath component were changed as shown below.

The core components of Examples 3 and 4 include methyl methacrylate 55
A polymer obtained by polymerizing parts by weight of N-methyldimethacrylamide and 45 parts by weight by a bulk polymerization method was used. The optical transmission performance and heat resistance of the optical fiber barcode are also shown in the table.

Comparative Example An optical fiber cord was obtained in the same manner as in Example 1 except that a sheath material and coating resin made of an ultraviolet curable resin composition containing no antioxidant were used. The optical transmission loss of the optical fiber barcode was 930 dB/km, but it was 40 dB/km at 125°C.
After 00 hours of treatment, both the sheath component and the coating resin progressed in coloring, and the optical transmission loss increased to 1920 dB/km.

Claims (1)

[Claims] The sheath component of the core-sheath type plastic optical fiber is formed from an ultraviolet curable polymer having a lower refractive index than the core component polymer and containing an antioxidant, and the outer layer of the optical fiber is formed of an ultraviolet curable polymer containing an antioxidant. A plastic optical fiber coated with ultraviolet curable resin.