JPH0359601A - Method and device for manufacturing plastic optical transmission fiber - Google Patents

Abstract

PURPOSE:To manufacture the plastic optical transmission fiber which has small variation in diameter and superior in roundness by extruding both plastic for a core material layer and plastic for a sheath material layer into a cooled guide cylinder by a composite spinning method and cooling them. CONSTITUTION:The plastic for the core material layer and the plastic for the sheath layer which has a lower refractive index than the core material layer are both extruded from a spinning opening 5 into the cooled guide cylinder 1 which has substantially on air flow by the composite spinning method and cooled. This cooled type guide cylinder 1 is a double circular cylinder (Liebig cooler) type and equipped with a flow passage formed of an cylindrical internal and an external wall, and a cooling medium exit 4 is formed in the external wall at the upper part. The upper end opening part of this cooler type guide cylinder 1 is connected to a spinning mandrel 5 through a heat insulator 6 in an airtight and heat-insulated state. Consequently, the superior fiber which has small variation in diameter and circularity and has small transmission loss can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a plastic-2 optically transmitting fiber and an apparatus for manufacturing the same. More specifically, there is a method for producing a plastic optical fiber with little diameter variation and low transmission loss, which can be suitably used as an optical communication means, and a method for producing such an excellent optical transmission fiber. This invention relates to a manufacturing device with a simple configuration.

[Prior art and problems to be solved by the invention] In recent years, optical fibers for optical transmission have become more resistant to bending stress, easier to handle, and cheaper than inorganic glass optical fibers that have been widely used. The development of plastic light transmitting fibers is progressing and being put into practical use.

This plastic optical fiber has a core material layer made of a polymer with excellent light transparency, and a sheath material layer made of a polymer with a lower refractive index than the core material layer and excellent transparency. It is generally made of two materials, and is produced by extruding these two materials into a two-layered fiber using a composite spinning machine.

What is important in such a manufacturing method is how to suppress the variation in diameter between the core material layer and the sheath material layer to achieve composite spinning.

As a technology with such ingenuity, JP-A-8L-1
(Publication No. 52H discloses that a core material layer, a sheath material layer, and a protective layer are the basic structural units, and after extruding each layer component of the basic structural units by a composite spinning method, the plastic shaped light is shaped by cooling. a transmission fiber, the protective layer is formed of a polymer having a glass transition temperature higher than the glass transition temperature of the polymer constituting the core material layer, and the cooling is performed at a temperature higher than the glass transition temperature of the protective layer polymer and the core material layer; A plastic light transmitting fiber is disclosed which is characterized by cooling at a cooling rate of 10-10,000°C/Sec(7) in a temperature range including the glass transition temperature of the material layer polymer. , air, nitrogen gas as the preferred cooling means.

Gas spraying such as argon gas and carbon dioxide gas is disclosed,
An air flow of 0.5 m/sea is disclosed as a specific cooling means.

Further, Japanese Patent Application Laid-Open No. 63-303304 proposes a technique for heating and stretching plastic fibers under certain conditions. This publication also states that the cooling air speed is 0.4
A spinning method is disclosed in which cooling is performed at m1sec.

However, plastic light transmittance! It has been found that in a-male fibers, if forced cooling is performed by airflow or the like at the exit of the spinneret of a composite spinning machine, the diameter and roundness of the fibers tend to fluctuate, making it difficult to obtain uniform and excellent m#1. This problem still cannot be solved even if the conventional air cooling method is adopted without using forced cooling because air currents are generated around the running fibers.

It is an object of the present invention to solve the above-mentioned problems and to provide a plastic optical transmission material with little variation in diameter and excellent roundness.
An object of the present invention is to provide a method for manufacturing ts and an apparatus for carrying out the method.

[Means for Achieving the Object] The present invention for solving the above-mentioned problems uses a composite spun material comprising a plastic for the base material layer and a plastic for the sheath material layer having a lower refractive index than the core material layer. A method for producing a plastic light-transmitting fiber is characterized in that the fiber is co-extruded from a spinneret into a cooled guide tube substantially free of airflow and cooled. At the exit of the spinneret.

The production of the plastic optical transmission fiber is characterized in that it is provided with a hollow cooling type guide tube connected in an airtight manner!
It is.

Next, the method of the present invention together with the apparatus of the present invention will be explained in detail.

1. Manufacturing device 1. The manufacturing device of the present invention includes:
It is provided with a hollow cooling type guide tube that is airtightly connected.

The cooling type guide cylinder is formed by a cooling cylinder having openings at both ends. This cooling cylinder has a structure that is equipped with a flow path through which a cooling medium can flow, and a cooling space that can cool the plastic light transmitting fiber extruded from the spinneret in a substantially windless state. There are no particular restrictions.

Here, "substantially no wind" means that no gas is blown into the cooling space.

As long as the wall surface forming the internal space of the cooling tube is made of a material with good thermal conductivity, such as metal, there are no particular restrictions on the material and shape of the cooling tube. It is preferable to attach the cooling type guide tube closely to the spinneret for extruding the fibers via a heat insulating material.The cooling type guide tube is not limited to one that is attached directly to the spinneret, but as long as it surrounds the spinning nozzle, it is suitable for spinning. If there is a gap between the spinneret and the insulating material, or between the insulating material and the cooling guide tube, which can be attached to the spinneret attachment part, air can enter and exit from the gap, creating an airflow in the space where the fibers pass, resulting in no-air flow. This is because it may become impossible to maintain this state.

FIGS. 1 and 2 show an example of a preferred embodiment of the cooling type guide cylinder of the present invention.

The cooling type guide tube shown in FIG. 1 is of a double cylindrical type and has a flow path formed by a cylindrical inner wall and an outer wall, and a cooling medium is provided below the outer wall. An inlet 3 is formed and a cooling medium outlet 4 is formed above the outer wall. A portion between the upper ends of this cooling type guide cylinder is connected to the spinneret 5 through a heat insulating material 6 in an airtight and heat-insulated manner.

The cooled guide tube shown in FIG. 2 is of a pipe type. That is, as shown in FIG. 2, the coil has a structure in which a pipe is spirally wound without any gaps, and the internal space 1 of this coil, which is formed into a cylindrical shape by spirally winding the pipe, is a light transmitting fiber. A coolant inlet 3 is provided below the coil, and a coolant outlet 4 is provided above the coil. In this cooling type guide cylinder as well, the spinneret 5 and the cooling type guide cylinder formed in a coil shape from a pipe are connected through a heat insulating material 6 in an airtight and heat insulating state.

In both of the cooled guide tubes shown in FIGS. 1 and 2, the cooling medium may be either liquid or gas, and from the viewpoint of economy and ease of handling, water or Cooling air or the like is preferred.

Moreover, a heat pump method can also be used as a cooling method.

The temperature of the space inside the cooling guide cylinder is determined by the type of spinning resin, spinning speed, etc. If the guide cylinder is not cooled at this point, the temperature will rise and the tensile tension of the spun fibers will decrease, resulting in large yarn sway, making it impossible to obtain the excellent plastic light-transmitting fiber that is the object of the present invention.

The length of the cooling guide cylinder can be arbitrarily selected according to the manufacturing conditions of the plastic light transmitting material, and is not particularly limited. Usually, it is 5 to 150 cm. Conventional cooling methods can optionally be used for further cooling after cooling under no air flow conditions. i.e. forced cooling with air or wood,
Alternatively, air cooling and water cooling may be combined.

1. Manufacturing method 1. The plastic light transmitting fiber in the manufacturing method of the present invention has a core material layer made of a plastic with excellent light transmittance, and a core material layer made of a plastic having a lower refractive index than this core material layer and having excellent transparency. It is composed of a sheath material layer made of plastic.

Alternatively, a plastic light-transmitting fiber may be formed by further laminating a protective layer on the outer surface of the sheath material layer.

The plastic used as the core material layer has a refractive index greater than the refractive index of the sheath material layer by 0.01 or more,
Specific examples of such plastics for the base layer include polymers with excellent transparency such as methacrylic polymers, polycarbonates, polystyrene, styrene-methacrylate copolymers, polyolefins, and hydrogen atoms of these polymers. Examples include transparent non-grade thermoplastic resins such as deuterated polymers in which all or part of the deuterium atoms are substituted with deuterium atoms. Furthermore, blends of the various polymers mentioned above or non-grade polymers other than those mentioned above can also be used as the plastic for the base layer.

As the plastic for the base layer, methacrylic polymers and polycarbonates are preferred, and polycarbonate is particularly preferred.

As the methacrylic polymer, for example, a homopolymer or copolymer of methyl methacrylate (70% by weight or more of the starting monomer is methyl methacrylate,
% or less is preferably other monomers copolymerizable with methyl methacrylate. Examples of monomers copolymerizable with methyl methacrylate include methyl acrylate,
Examples include vinyl monomers such as ethyl acrylate.

Copolymers of methacrylic acid esters such as cyclohexyl methacrylate, t-butyl methacrylate, inbornyl methacrylate, adamantyl methacrylate, benzyl methacrylate, phenyl methacrylate, naphthyl methacrylate, etc. and hetamine copolymerizable with these, etc. can be mentioned.

Among these, homopolymers and copolymers of methyl methacrylate are preferred.

Suitable polycarbonates include, for example, 1+0-R-0-(1-8 fortune telling , where the R is:

CH3CH3 ＼　　／ ／　　＼ CH3CH3 Alicyclic polycarbonate represented by

Examples include aromatic polycarbonates shown in the following.

In addition, these and 4,4°-dioxydiphenyl ether, ethylene glycol, P-xylylene glycol, 1
．． Copolymers with dioxy compounds such as 8-hexanediol can also be used.

From the viewpoint of heat resistance etc., the heat distortion temperature (ASTMD-
848, load 4.8 kg/cm2) is preferably 120°C or higher, more specifically, aromatic polycarbonate.

Aromatic polycarbonates having repeating units represented by are particularly preferred.

As for the polymer used as the sheath material layer.

A! +1 The refractive index is 0.01 or more lower than the polymer of the material layer component,
Specific examples of such polymers for the sheath material layer include polymethyl methacrylate, styrene-methyl methacrylate copolymer, poly-4-methylpentene-1, ethylene-
Vinyl acetate copolymer, polycarbonate, fluorine-containing polymethyl methacrylate, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer, methyl methacrylate-styrene, vinyltoluene or α-methylstyrene/ Examples include maleic anhydride ternary copolymers and quaternary copolymers. Among these, vinylidene fluoride-fluoroolefin copolymer poly-4-methylpentene-1 and polycarbonate having a structure represented by the following general formula are used.

This is particularly preferable in terms of low optical transmission loss.

Among these, fluorinated polycarbonate polymers are preferred because they have good heat resistance and good compatibility with the core layer polymer.

However, a and b in the above formula represent the respective molar amounts of repeating units in the polymer.

The polycarbonate represented by the formula (I) suitable for the sheath material layer may be a block copolymer of two types of repeating units in the formula (I) or a random copolymer. Preferred are random copolymers.

Furthermore, in the formula (I), (a/a+b)×100
It is desirable that the value is 20 or more; if this value is less than 20, optical transmission loss may increase. In addition,
b may be 0, and the glass transition temperature (Tg) of the polycarbonate represented by the formula (I) is usually 157° C. or higher and the refractive index is 1.57 or lower.

The plastic light transmitting fiber of the present invention is produced by a composite spinning method in which, for example, the plastic constituting the sheath material layer and the plastic constituting the core material layer are melted and discharged from a spinneret using a special die. .

What is important in the method of the present invention is that the plastic for the core material layer and the plastic for the sheath material layer are co-extruded from a spinneret into a cooling guide tube substantially free of airflow by a composite spinning method. That's true.

Here, the cooling guide cylinder is as described above.

The length of the cooling guide tube, that is, the effective length of the spun plastic light transmitting fiber while being cooled, is determined by using, for example, polycarbonate as the core material and poly(4-methyl) as the sheath material layer. Adopts Penten-1, the diameter of the nozzle is 3 mm,
When the nozzle temperature is 240-280°C, 5-1
00 cm, preferably 10 to 80 cm.

When the spun plastic light transmitting fiber is forcibly cooled using the cooling guide tube of the present invention, a temperature rise is effectively prevented within the cooling guide tube, so that the tensile tension of the plastic light transmitting fiber ( There is no decrease in tension (between the nozzle and the take-up roll).

In addition, a plastic optically transmitting fiber is produced that has no yarn sway and extremely little variation in diameter.

The subsequent treatment of the plastic light transmitting fibers that have passed through the cooling guide cylinder is optional.

[Example] Next, an example of the present invention will be shown and the present invention will be explained in more detail.

(Example 1) A commercially available polycarbonate (manufactured by Idemitsu Petrochemical Co., Ltd., refractive index 1.585, T g 148) was used as a core material wear polymer.
°C) and poly-4-methylpentene-1 (manufactured by Mitsui Petrochemicals, refractive index 1.483) as a polymer for the sheath material layer.
, T g 240°C) from the spinneret (nozzle diameter: 3 φ) of a composite spinning machine, and the inside of the cylinder, which was airtightly connected to the spinneret and cooled by passing cooling water, was maintained in a substantially windless state. Co-extruded into the cooling guide cylinder, 20m/
A plastic light transmitting fiber having a core material layer diameter of 980←m and a sheath material layer thickness 10 JLm was obtained.

Here, the cooling type guide cylinder used was of a double cylindrical type (the type shown in FIG. 1) with an inner diameter of 75 cm and a length of 450 cm.

About the obtained plastic light transmitting fiber.

The optical transmission loss at 880 m and the diameter variation (%) were measured using a laser outer diameter measuring device.

The results are shown in Table 1.

(Example 2) Fluorinated polycarbonate (
Refractive index 1.50. Plastic optical transmittance m#I was obtained in the same manner as in Example 1 except that Tg 180.70°C) was used.

In this case, the diameter variation is ±1.1% and the transmission loss is 5
It was 80 dB/km.

(Comparative Example 1) In Example 1, spinning was attempted without flowing cooling water into the cooling type guide tube, but the yarn swayed so much that spinning was impossible.

(Comparative Example 2) In Example 1, spinning was carried out under natural cooling conditions without using the cooling type guide tube.

The results are shown in Table 1.

(Comparative Example 3) A plastic light transmitting fiber was obtained in the same manner as in Example 2, except that the guide tube was not used.

In this case, the diameter variation is ±4.8% and the transmission loss is 7
It was 80 dB/km.

As is clear from Table 1, when cooling is performed by passing cooling water through a cooling type guide tube (Example), the diameter of the optically transmitting fiber obtained is smaller than when there is no cooling type guide tube (Comparative Example 2). It is shown that fluctuations and optical transmission losses are extremely small.

Table 1 [Effects of the Invention] According to the method of the present invention, plastic light transmitting fibers are manufactured using a composite spinning machine equipped with a cooling guide tube.
Fluctuations in diameter and roundness are smaller than in conventional methods that do not use a cooling guide tube, and excellent fibers with low transmission loss can be obtained.

Further, the apparatus of the present invention has a simple structure and can produce the above-mentioned excellent plastic light transmitting fiber.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a double cylindrical type cooling type guide tube according to the present invention, and FIG. 2 is a sectional view of a pipe type guide cylinder. ! ...Cooling space of the guide tube, 2.. Plastic light transmitting fiber, 3.. Cooling medium inlet, 4.. Cooling medium outlet, 5.. Spinneret, 6.. Heat insulating material. Figure 1 Figure 2

Claims (2)

[Claims] (1) A plastic for the core material layer and a plastic for the sheath material layer having a lower refractive index than the core material layer are spun into a cooled guide tube with substantially no airflow using a composite spinning method. A method for producing a plastic light transmitting fiber, characterized by coextruding it from a die and cooling it. (2) Used in the method for producing a plastic light-transmitting fiber according to claim 1, characterized in that a hollow cooling type guide tube is provided at the outlet of a spinneret of a composite spinning machine. Manufacturing equipment.