JPH0368904A - Optical transmissible plastic fiber - Google Patents

Abstract

PURPOSE:To improve moldability, transparency, refractive index and transmission loss by having a core layer consisting of polycarboate and a clad layer consisting of a ternary copolymer of vinylidene fluoride, tetrafluoroethylene and hexafluoropropylene. CONSTITUTION:A polycarbonate resin is used as the core layer of the optical transmissible fiber. The resin having the viscosity average mol. wt. ranging, for example, to 18,000 to 28,000 is more preferable. The optical properties, such as transparency, refractive index, and transmission loss, of the optical transmissible plastic fiber can be improved while the sufficient strength and good moldability thereof are assured if this viscosity average mol. wt. is in the 20,000 to 2,600 range. The ternary copolymer of the vinylidene fluoride, tetrafluoroethylene and hexafluoropropylene is then combined as the resin to form the clad layer when the core layer is formed of the polycarbonate. The heat resistance is improved in this way.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to a plastic light transmitting fiber, and more specifically, the present invention relates to a plastic light transmitting fiber that can be suitably used, for example, in the fields of electricity, electronics, automobiles, etc. This invention relates to a plastic optical fiber with low loss and excellent heat resistance.

[Prior art and problem B to be solved by the invention] Conventionally, inorganic glass optical fibers made of inorganic glass such as quartz have been used as optical transmission fibers for industrial, medical, decorative, and other purposes.
It is also widely used for information transmission.

However, inorganic glass light transmitting fibers have problems in that they are expensive, heavy, and have poor flexibility.

Therefore, the development of plastic light transmitting fibers is underway, which is more resistant to bending stress than inorganic glass light transmitting fibers, easier to handle such as connections, and moreover inexpensive.

Such plastic light transmitting fibers generally have a core material layer made of a resin with excellent light transmittance and a sheath material made of a resin with a refractive index smaller than that of the core material layer and excellent in transparency. It is desirable that the structure be composed of layers.

Therefore, for example, a plastic light transmitting mta using vinylidene fluoride copolymer resin as the sheath material layer has been proposed (Japanese Patent Application Laid-Open Nos. 52-154643 and 1982-80).
(See Publication No. 758).

However, since the core material layer of these materials is polymethyl methacrylate (PMMA)-based resin, they have poor heat resistance and cannot be used, for example, in parts around automobile engines.

In addition, a plastic light transmitting fiber using polycarbonate resin as the core material and a binary copolymer of vinylidene fluoride and tetrafluoroethylene as the sheath material has also been proposed (Japanese Patent Application Laid-Open No. 57-46204). .

However, this method has a major problem with optical transmission loss.

An object of the present invention is to provide a plastic light transmitting fiber with excellent heat resistance and low light transmission loss.

[Means for Solving the Problems] The present invention for solving the problems described above includes a core material layer made of polycarbonate and a sheath made of a terpolymer of vinylidene fluoride, tetrafluoroethylene, and hexafluoropropylene. This is a plastic light transmitting fiber characterized by having a material layer.

The present invention will be explained in more detail below.

Core 1L Treatment As the polycarbonate resin used as the core material layer in the plastic optically transmitting fiber of the present invention, various types of polycarbonate can be used without particular limitation.

However, the most suitable polycarbonate for plastic optical transmission fibers is one with a viscosity average molecular weight of 18,000.
~28. Rollo 0, preferably zo, ooo ~ 25.00
It is desirable that it be within the range of 0.

The viscosity average molecular weight referred to here is determined by measuring the specific viscosity ηsp of a methylene chloride solution at 20°C and using the formula %) C: Polycarbonate resin concentration (g/again) and [η] = 1.23X 10-5 Mv '
It can be found by 8 pieces.

Viscosity average molecular weight of polycarbonate resin
When it is in the range of oo~26,000, the plastic optically transmitting m-fiber ensures sufficient strength and good formability while ensuring improvement in optical properties such as transparency, refractive index, and transmission loss. I can do it.

The viscosity average molecular weight of the polycarbonate resin is 18.0.
In order to adjust it within the range of 00 to 28,000, in the production of polycarbonate resin described below, p-tert
- An end capping agent such as butylphenol may be added.

Furthermore, the refractive index of the core material layer made of the polycarbonate resin is, in the case of bisphenol A polycarbonate,
It is 1.586.

From the viewpoint of rM thermal properties, a polycarbonate resin having a heat distortion temperature of 120° C. or higher is preferable. Here, the heat distortion temperature refers to a value measured at a load of 4.6 kg/c1 in accordance with AS-Cho MD 648.

Polycarbonate resin suitable as plastic optical transmission fiber has a molecular weight distribution [11w/Mn (GPC method)]
is usually within the range of 2.0 to 2.6, preferably 2.
It is within the range of 0 to 2.4.

In addition, in order to obtain a suitable polycarbonate resin, the polymer obtained during production is treated with a solvent such as acetone to reduce impurities such as low molecular weight components [Mv; 3,000 or less] and residual chlorine as much as possible. It is better to remove it.

Specific examples of polycarbonate resins preferred for the present invention are not particularly limited as long as they satisfy the above conditions.
It is also possible to use an alicyclic polycarbonate represented by the general formula (% formula %) in which R is represented by the above general formula, or a copolymer with a dioxy compound.

Preferred polycarbonate resins in the present invention include aromatic polycarbonates represented by the following.

Furthermore, it is an aromatic polycarbonate having repeating units represented by these and 4,4°-dioxydiphenyl ether, ethylene glycol, P-phenylene glycol, 1,6-hexanediol, etc.

Note that the polycarbonate resin in the present invention may have a partially branched structure.

There are no particular restrictions on the method for producing the polycarbonate resin, and suitable methods include, for example, the phosgene method by reacting dihydric phenol with phosgene, the transesterification method by reacting dihydric phenol with a carbonate ester such as diphenyl carbonate, etc. Can be adopted by

The dihydric phenol includes hydroquinone, 4,4
°-Dioxyphenyl, bis(hydroxyphenyl)alkane, bis(hydroxyphenyl)cycloalkane,
Bis(hydroxyphenyl) ether, bis(hydroxyphenyl) sulfite, bis(hydroxyphenyl)
Examples include sulfone and substituted products thereof such as lower alkyl and halogen.

Among these dihydric phenols, 2,2'-bis(4-
Hydroxyphenyl> Propane (hereinafter sometimes referred to as bisphenol A). ], ]1,1-bis4-hydroxyphenyl)ethane, z,2'-bis(4-hydroxyphenyl)-hexafluoropropane, etc. are preferred.

Further, these dihydric phenols may be used alone or in combination.

Amount 1 In the present invention, it is important to use a terpolymer of vinylidene fluoride, tetrafluoroethylene, and hexafluoropropylene as the resin forming the sheath material layer. Moreover, when the core material layer is formed of polycarbonate, it is meaningful to combine the above-mentioned specific terpolymer as the sheath material layer.

For example, when polymethyl methacrylate is used as the core layer, the object of the present invention cannot be achieved even if the terpolymer is used as the sheath layer.

In the present invention, there is no particular restriction on the ratio of each component in this terpolymer, but usually vinylidene fluoride is contained in an amount of 20 to 90% by weight.
, 5 to 70% by weight of tetrafluoroethylene, and 3 to 68% by weight of hexafluoropropylene.

In the present invention, the terpolymer may contain, in addition to the three monomer units, a small amount of fluorine-containing olefin such as chlorotrifluoroethylene or fluoroalkyl vinyl ether, to the extent that the object of the present invention is not impaired. may contain monomer units derived from methacrylic esters and acrylic esters such as methyl methacrylate and methyl acrylate, and heptanomer units derived from vinyl esters such as vinyl acetate. .

Further, it is desirable that the refractive index of the terpolymer in the present invention is within the range of 30 to 1.41.

The terpolymer in the present invention further has a melting point of 10
It is desirable that the melting point be within the range of 0 to 200°C, and good heat resistance can be obtained by having the melting point within this range.

In addition, the terpolymer in the present invention has a copolymer composition ratio,
Its crystallinity changes greatly depending on random copolymerization, block copolymerization, etc.

However, it is not limited to crystallinity as long as it is suitable for the purpose of the present invention.

Therefore, the melting point includes those that show a clear melting point in DSC measurement and those that show a very small melting energy.

Furthermore, it is desirable that the terpolymer has good melt fluidity.

The terpolymer can be produced by a known method using an emulsion polymerization method or a suspension polymerization method using an inorganic or organic peroxide or redox catalyst under a pressure of 20 to 200 atmospheres.

±1 and other plastic light transmitting fibers of the present invention may have a protective layer as an outer layer of the sheath material layer, if necessary.

This protective layer is preferably formed of a resin having higher heat resistance than the sheath material layer. By forming such a protective layer, the heat resistance of the optically transmitting fiber of the present invention is improved.

Examples of the resin used in the protective layer include polyester, liquid crystalline polyester, polyamide, poly-4 to methylpentene-1, polyvinylidene fluoride, polyacetal, polysulfone, polytetramethylene terephthalate, polyethylene terephthalate, polypropylene, polyoxymethylene, Polybutene, ABSm fat.

Examples include so-called engineering plastics such as polyphenylene oxide, polycarbonate, and crosslinked polyolefin. Moreover, the polycarbonate resin used as the core material layer can also be used.

Furthermore, in order to improve the durability of the plastic optical fiber, the resin used for the protective layer may contain fillers such as carbon black, talc, silica, glass fiber, carbon fiber, and polyamide fiber.

The plastic light transmitting material 1a of the present invention can be produced by a coating method, or preferably by a composite spinning method as described below.

First, a polycarbonate resin as a raw material for the core material layer is supplied to a melt extruder that connects a spinning head, and a ternary resin is supplied to another melt extruder that is connected to the same spinning head so as to face the extruder. The polymer is supplied as a raw material for the sheath material layer. Then, the molten resin is passed through the spinneret at the tip of the spinning head to form a composite yarn such that the polycarbonate resin is coated with the terpolymer, and the resulting product is taken off by a take-off machine while being cooled to form a product.

In this manufacturing method, the temperature of the spinning head is generally set at 2
Composite spinning may be carried out within the range of 40 to 280°C.

In addition, the distance AI from the spinneret of the spinning head to the take-up machine (
It is preferable to perform composite spinning while cooling with an air gap of 700 to 1:100 mm.

In this way, it is possible to always stably and easily manufacture plastic optically transmitting fibers with small outer diameter fluctuations and low optical transmission loss.

Cooling by an air gap may be natural cooling at room temperature or forced cooling. However, in composite spinning, a spinning tube equipped with a cooler is provided between the spinneret and the take-off machine, and the inside of the spinning tube is It is preferable to create a substantially windless state.

An example of the structure of the plastic light transmitting fiber manufactured in this way is an outer diameter of 400 to 1.000 g.
m, and the thickness of the sheath material layer is 5 to 50 ILm.

The plastic light transmitting fiber of the present invention has excellent heat resistance and low light transmission loss, so it can be used in fields where it has been impossible or difficult to use conventional plastic light transmitting fibers, such as the electrical and electronic fields. It can also be suitably used as a sensor means or an optical communication means in the automobile field, etc.

[Example] Next, the present invention will be described in more detail based on Examples and Comparative Examples.

(Example 1) A polycarbonate having a repeating unit derived from bisphenol A was used as the resin for the core material, and a vinylidene fluoride/tetrafluoroethylene/hexafluoropropylene terpolymer (melting point 114°C) was used as the resin for the sheath material.
1 refractive index 1.36) from a screw melt extruder set at 270°C and 230°C, respectively.
The material was supplied to a spinning head of a composite spinning machine having a spinneret of mmφ.

These resins were then extruded from a spinneret, cooled and solidified, and then bowed at a speed of 20 m/min to a diameter of 98 mm.
Plastic optical transmission property consisting of a core material layer of 0gm and a sheath material layer of thickness 10IL m! I got l.

Next is the optical transmission properties of this plastic! Divide the male into two parts, leave one part at room temperature, and incubate the other part at 120°C.
Heat treatment was performed for 150 hours.

Optical transmission loss at a wavelength of 660 nm was measured for these fibers (based on the method described in Japanese Patent Application Laid-open No. 7502/1983).

The results of these measurements are shown in Table 1.

(Comparative Example 1) Optical transmittance was measured under the same conditions as in Example 1, except that PMMA was used as the raw material for the core material and the temperature of the extruder for the core material was set at 240°C. Fibers were produced and their physical properties were evaluated.

The results are shown in Table 1.

(Comparative Example 2) A light transmitting m-fiber was produced in the same manner as in Example 1, except that poly 4-methylpentene-1 was used as the sheath material and the temperature of the extruder for the sheath material was set at 300°C. was manufactured.

The physical properties of this fiber are shown in Table 1.

(Comparative Example 3) The same procedure as in Example 1 was carried out, except that a binary copolymer of vinylidene fluoride and tetrafluoroethylene was used as the sheath material, and the temperature of the extruder for the sheath material was set at 240°C. A light transmitting fiber was manufactured and its physical properties were measured. The results are shown in Table 1.

According to Table 1, the optical transmission loss of the plastic in Example 1 of the present invention is less than 1,000 dB/km both at room temperature and after the heat resistance test, which means that the optical transmission loss is small (in other words, it is excellent). It has excellent optical transmission properties.

) and good heat resistance at the same time.

On the other hand, the optical transmission fibers of Comparative Examples 1 to 3, which deviate from the conditions of the present invention, have an optical transmission loss of 1,000 at room temperature.
Although it is good at dB/km or less, it exceeds 1,000 dB/km after the heat resistance test, and some exceed 3,000 dB/km.

In short, it lacks either heat resistance or optical transmission.
Not balanced.

[Effect of the invention] According to the present invention, compared to inorganic glass optical fiber, +
In addition to being strong against lh bending stress, easy to handle, and inexpensive, it also has excellent heat resistance and can be used in high-temperature areas such as automatic DL engine rooms. It is possible to provide a plastic optical transmission fiber with low optical transmission loss.

Claims (1)

[Claims] (1) A plastic light-transmitting fiber comprising a core material layer made of polycarbonate and a sheath material layer made of a terpolymer of vinylidene fluoride, tetrafluoroethylene, and hexafluoropropylene.