JPS59216104A - Optical transmission fiber - Google Patents

Abstract

PURPOSE:To obtain an optical transmission fiber having superior optical and mechanical properties, weather resistance, heat resistance and productivity by providing a core-sheath double structure consisting of a specified copolymerized methacrylate resin as a sheath component and a prescribed polymer as a core component. CONSTITUTION:A methacrylate resin is prepd. by copolymerizing 50-98wt% methyl methacrylate monomer or prepolymer thereof with 1-40wt% styrene or vinyl toluene and 1-25wt% maleic anhydride. The methacrylate resin as a sheath component and an aromatic polycarbonate polymer whose refractive index is higher than that of the methacrylate resin by >=1% as a core component are spun into a fiber with a vent type composite spinner provided with a spinneret having a core-sheath double structure. An optical transmission fiber having superior optical and mechanical properties, weather resistance, heat resistance and productivity is obtd.

Description

Detailed Description of the Invention Technical Field The present invention relates to a light transmitting fiber, and more specifically, the present invention relates to a plastic light transmitting fiber having a core-sheath dual structure and excellent heat resistance. It concerns fibers.

TECHNICAL BACKGROUND Conventionally, inorganic glass optical fibers having excellent optical transmission properties over a wide range of wavelengths have been known as optical fibers. However, glass fibers have poor processability (and are weak against bending stress) and are expensive, so optically transmitting fibers based on synthetic resins have been developed. The core component is a polymer with a thick refractive index (and good light transmittance), and a transparent polymer with a lower refractive index than the core component polymer is used as a sheath component. It is obtained by producing fibers with a layered structure.The polymer useful as a core component with high optical transparency is preferably an amorphous material, with polymethyl methacrylate or Boristyrene being used for the core.

Among these, polymethyl methacrylate has excellent not only transparency but also mechanical properties, weather resistance, etc.

Therefore, it is used industrially as a core material or sheath material for high-performance plastic optical fibers, and its applications are being developed in fields such as short-distance optical communications and original sensors. However, polymethyl methacrylate has a heat distortion temperature of around 100°C on the negative side, and does not have sufficient heat resistance, so there are many fields where its application is restricted, and there is a strong demand for improved heat resistance. .

For information on how to improve the heat resistance of methacrylic resin,
The following methods are known.

(1) A method of copolymerizing methyl methacrylate and α-methylstyrene.

(2) A method of dissolving poly-α-methylstyrene in methyl methacrylate monomer and then polymerizing methyl methacrylate (Japanese Patent Publication No. 1616-1987, Japanese Patent Publication No. 49-87
No. 18).

(3) Method of copolymerizing methyl methacrylate and N-allylmaleic acid imide (Japanese Patent Publication No. 1983-9753)
.

(4) Methyl methacrylate/α-methylstyrene//
A method of copolymerizing maleimide.

and (5) a method of polymerizing methyl methacrylate in the presence of a crosslinked polymer using a polyfunctional monomer (JP-A-48-95
No. 490, JP-A-48-95491).

However, in these conventional methods, although the heat resistance of the obtained polymer is improved, the -plane polymerization rate is extremely small, resulting in a marked decrease in productivity, making it impractical, or Mechanical properties may be insufficient, or
They have not yet reached a stage where they can be put to practical use because they have insufficient optical properties, are markedly colored when molded, or have poor moldability.

OBJECT OF THE INVENTION The object of the present invention is to provide a resin that not only has excellent optical properties, mechanical properties, weather resistance, and moldability comparable to polymethacrylic acid ester resins, but also has excellent heat resistance and productivity. An object of the present invention is to provide a light-transmitting fiber having a sheath component polymer having excellent heat resistance and transparency, and a core component polymer having excellent heat resistance and transparency.

Structure of the Invention The light-transmitting fiber of the present invention comprises: 50 to 98% by weight of methyl methacrylate monomer or partial polymer;
~40% by weight of styrene or vinyltoluene and (C
) a sheath component made of a methacrylic resin obtained by copolymerizing a mixture consisting essentially of 1 to 25% by weight of maleic anhydride; and ``the refractive index of the sheath component copolymer coated with the sheath component. It is characterized by comprising a core component made of a polymer having a refractive index 1% or more higher than that of the core component.

In the light transmitting fiber of the present invention, the sheath component methacrylic resin substantially contains the above-mentioned (4), (B) and (C10 copolymer component), and is a combination of these three components. With this, an unexpected synergistic effect was obtained, showing high heat resistance, excellent moldability, light transmission and mechanical properties that could not be achieved with conventional two-component copolymer resins, and excellent productivity. By using a sheath component polymer with such excellent properties, a well-balanced sheath component resin was obtained in terms of light transmission, mechanical properties, adhesion to the core component, and various other performances. A fiber with excellent light transmission properties was obtained.

In the light transmitting fiber of the present invention, the sheath component polymer substantially comprises (A) 50 to 98% by weight, preferably 55 to 94% by weight.
% by weight of methyl methacrylate monomer or partial polymer; (B11 to 40% by weight, preferably 1 to 25% by weight)
of styrene/or vinyl toluene/(Q) and (Q) 1 to 25% by weight, preferably 5 to 20% by weight of maleic anhydride as copolymerization components. Among the above copolymerization components, methyl methacrylate monomer or partial polymerization)
is a necessary component for maintaining basic optical properties, weather resistance, and mechanical properties as a light transmitting fiber. (
If the content of the Al component is less than 50% by weight, the above-mentioned basic properties will be insufficiently maintained in the resulting copolymer; The effect of improving the heat resistance of the copolymer becomes insufficient.

Copolymerization component (Al is methyl methacrylate monomer or partial polymer, and a small amount, preferably 20% by weight or less, of other copolymerization components, such as acrylic acid, methacrylic acid, methyl acrylate, methacrylic acid It may contain at least one monomer or partial polymer selected from ethyl, butyl methacrylate, glycidyl methacrylate, and the like.

In particular, those containing polar functional groups such as methacrylic acid and glycidyl methacrylate are preferred components since they improve adhesiveness with the core component.

Copolymerized molecule B consisting of styrene or vinyltoluene
Although I itself is not a component that can improve the heat resistance of the resulting copolymer, it is a heat resistance improving component, that is, a copolymerization component consisting of maleic anhydride (which increases the copolymerization reactivity of Cl, thereby increasing the copolymerization reactivity of Cl). It indirectly contributes to improving the heat resistance and productivity of the copolymer obtained.In addition, the copolymer component (Bl) is a copolymer component that improves the mechanical properties, transmission performance, and molding processability of the copolymer obtained. This effect of improving mechanical performance and optical transmission performance is due to the effect of the previously known copolymerization of styrene and vinyltoluene (a new and unexpected effect). A copolymer component consisting of styrene or vinyltoluene (the blending ratio of Bl is 1 to 40
% by weight is required. If the amount used is less than 1% by weight, the productivity of the copolymer will be low, and if the amount used is more than 40% by weight, the heat resistance and optical properties of the resulting copolymer will be unsatisfactory. Because it will be.

Vinyltoluene may be any of ortho form, meta form, para form, and a mixture of two or more of these forms.

The copolymer component (C1) consisting of maleic anhydride has the effect of improving the heat resistance of the resulting copolymer through interaction with the copolymer component tBl.
I is used in an amount of 1 to 25% by weight. The amount used is 1
If the amount is less than 25% by weight, the resulting copolymer will have insufficient heat resistance, and if the amount exceeds 25% by weight, the resulting copolymer will have unsatisfactory mechanical properties and moldability. do not have.

Considering the balance of productivity, heat resistance, mechanical properties, optical properties, moldability, etc., the sheath component copolymer of the present invention is anhydrous maleic of the copolymer molecule Bl consisting of styrene or vinyltoluene. The molar M ratio (α/β) to the copolymer component (C) consisting of acid is 0.9 to 1.7
It is preferable that it is within the range of . Molar weight ratio (α/β)
If the value is less than 0.9, the mechanical properties, water resistance, and optical properties of the resulting copolymer may deteriorate slightly, and if it exceeds 1 or 7, the heat resistance of the resulting copolymer may deteriorate. It may decrease slightly.

The sheath component copolymer used in the present invention is obtained substantially from the copolymer components (4), (B), and (C), but in addition to these copolymer components, a small amount of preferably may contain a copolymerization component (Dl) having a weight ratio of 20 or less. This copolymerization component (Dl can be selected depending on the purpose, for example, methacrylic acid, acrylic acid, methyl acrylate, ethyl acrylate, vinyl acetate, glycidyl methacrylate) , methylglycidyl methacrylate, methacrylamide, etc., as well as divinylbenzene, triallyl cyanurate, triallyl isocyanurate, ethylene glycol dimethacrylate, )! It may consist of one or more types selected from polyfunctional crosslinkable monomers such as J ethylene glycol dimethacrylate, trimethylolpropa/trimethacrylate, and the like.

As a method for producing the sheath component copolymer of the present invention, a radical polymerization catalyst is added to the mixture of the copolymerization components, and the resulting copolymerization mixture is first heated at 50 to 150°C, preferably 65 to 120°C. to a temperature of The polymerization is advanced by heating to a temperature of 100 to 160 °C.
The polymerization is completed by heating for 30-180 minutes at a temperature of .degree. This method is a so-called bulk polymerization method.

Further, the above polymerization can also be carried out by a so-called suspension polymerization method in which the polymerization is carried out in an aqueous medium containing a suspending and dispersing agent. However, generally the bulk polymerization method is the simplest method.

As a method for preparing the above-mentioned slag-like partial polymer,
Copolymerization component (A) consisting of methyl metatallylate partial polymer
), or a method of mixing and dissolving the copolymerization component (Bl and (C)), or adding a homopolymer or copolymer of methyl methacrylate to the methyl methacrylate monomer and copolymerization component (B).
There is a method of dissolving it in a monomer mixture of :M and (C1. At this time, the composition of the polymer in the silty partial polymer and the composition of the monomer mixture may not be the same.

In addition, the sheath component polymer includes the above-mentioned copolymerized components (Al, (Bl
and (C) may consist of a mixture of such a copolymer and a polymer containing 80% or more of methyl methacrylate. 80% by weight of the latter methyl methacrylate
The mixing ratio of the above-mentioned polymers can be in the range of 1 to 99% by weight, but it can be in the range of 15 to 5% by weight if the heat resistance and total light transmittance of the core component to be obtained are taken into consideration. preferable.

The radical polymerization catalyst used to prepare the sheath component copolymer of the present invention is one that is used in general radical polymerization, such as azobisisobutyronitrile, 2,2'-
Azobis-based catalysts such as azobis-(2,4-dimethylvaleronitrile), diacyl-oxide catalysts such as lauroyl peroxide, benzoyl peroxide, bis(3,5,5-)limethylhexanoyl) peroxide, and You can choose from percarbonate catalysts, etc.

In the light transmitting fiber of the present invention, a substantially transparent polymer having a refractive index lower (by 1% larger) than the refractive index of the sheath component copolymer is used as the core component.

As the polymer for the core component of the present invention, for example,
Polymers or copolymers of esters consisting of methacrylic acid and alcohols having an aromatic ring as described in Japanese Patent Publication No. 49415, aromatic amorphous polyesters as described in Japanese Patent Publication No. 52-385, and styrene. , α−
It can be selected from polymers or copolymers made of vinyl monomers bonded with aromatic groups such as methylstyrene, and polymers such as aromatic polyethers, aromatic polycarbonates, and aliphatic aromatic polycarbonates.

Among these, α-methylstyrene polymers or aromatic polycarbonates are preferred as core component polymers suitable for optically transmitting fibers with excellent transparency and heat resistance.

In the light transmitting fiber of the present invention, the refractive index value of the core component must be at least 1 inch larger than that of the sheath component. If the difference in refractive index between the two components is less than 1 inch, the numerical aperture of the resulting light-transmitting fiber will be too small, making it difficult to use practically. Also, if the refractive index of the core component is smaller than that of the sheath component, the resulting fiber will not transmit light ().

In order to improve the durability of the light transmitting fiber when exposed to high temperatures for a long period of time, the core component polymer as well as the sheath component polymer should have a heat distortion temperature as high as possible, preferably 70°C or higher.
More preferably 100°C or higher, even more preferably 120°C
It is desirable that the material has a heat distortion temperature of ℃ or higher.

The core-sheath dual structure light transmitting fiber of the present invention is manufactured by the method described below.

(1) A composite spinning method in which the core component copolymer 3 and the sheath component polymer are respectively melted and extruded into a core-sheath structure using a special nozzle force.

(2) A coating method in which a core component fiber is formed from a core component copolymer, coated with a solution of a sheath component polymer, and then the solvent is removed from this coating layer. 48-131391, the core component polymer may be continuously polymerized in bulk and then spun into a single bow to form the core component fiber. This is effective in reducing performance loss.

Next, the present invention will be specifically explained using examples.

EXAMPLES In the examples, the optical transmission performance of the fibers is as follows:
Measurement and evaluation were carried out using the device shown in Figure 4 of Publication No. 7602.The measurement conditions were as follows: Interference filter (main wavelength) 770 μm l. (total length of fiber) 5 mA (cutting length of fiber) 4yyiD (bobbin diameter) 19
0 Example 1 Methyl methacrylate 6600 J', Styrene/1900
, P, maleic anhydride 1600. P, t-dodecyl mercaptan 33P was placed in a reaction vessel equipped with a cooling tube, a thermometer, and a stirring bar, and the mixture was heated with stirring until the internal temperature reached 7.
Add 0.8y of 2,2'-azobis-(2,4-dimethylnochloronitrile/l/) at 0°C, and raise the internal temperature to 95°C.
The temperature was raised to ~110°C and held for 10 minutes. Next, the reaction mixture was cooled to room temperature to obtain a silt-like partial polymer. This partially polymerized product was purified using a 0.1μ filter manufactured by Polytetrafluoroethyl Vy, and 0.38 parts by weight of t-dodecyl mercaptan and 0.4 parts by weight of lauroyl peroxide were added to 100 parts by weight of the obtained purified product. parts by weight and 100 ppm of JP-504 (manufactured by Johoku Kagaku Co., Ltd.) as a release agent. A thermocouple was set, and the above composition was injected into the cell, immersed in warm water at 80°C, and polymerized and cured.

The time from immersion in hot water until reaching the internal temperature peak (hardening time) was measured, and 30 minutes after reaching the peak temperature, the product was taken out of the hot water and then placed in an air heating oven at 120°C for 2 hours. Heat treated. After cooling, the cell was removed, and the resulting resin plate with a thickness of about 6 mm was crushed in a clean box to obtain a sheath component copolymer. The obtained sheath component polymer had an MI (230°C1 load of 3.8 ky) of 2. Good luck, refractive index p is 1,510, heat distortion temperature HDT is 122
It was ℃.

On the other hand, a polycarbonate solution obtained by reacting bisphenol A with phosgene in the presence of an aqueous caustic soda solution and methylene chloride was washed with a large amount of water, and then methanol was added to the solution while stirring. The polycarbonate precipitated into a fine powder was separated, washed again with acetate, and dried to obtain a polycarbonate having a refractive index rLD of 1.58 and a heat distortion temperature of 140° C., which was used as a core component polymer.

The obtained core and sheath component polymers were supplied to a composite spinning machine having a core-sheath two-layer structure spinneret, and taken at a spinning temperature of 240° C. and a spinning speed of 6 m/min.
I rolled it up.

The obtained fiber had a core component diameter of 980 μm and a sheath component thickness of 10 μm.
It was a light transmitting fiber with a concentric structure of μ7n and a weight ratio of core component to sheath component of 96:4.

The optical transmission loss of this optical transmission fiber is 1300 dB/km.
The length of 10771 was enough to transmit an optical signal.

The obtained optical transmission fiber was coated with carbon black polyester elastomer as a jacket using a crosshead type cable processing machine so that the outer diameter was 2.2 mm to obtain an optical fiber cable with an optical transmission loss of 1330 dB/lan. Ta.

Cut 10m of this original fiber cable and fix one end to a light source (using a 770μm interference filter).
The other end was connected and fixed to a photodiode, and the 5 m middle portion of the optical fiber cable was exposed to a hot air heating furnace at 130° C., and the heat resistance and durability of the original fiber cable was evaluated by tracking changes in the amount of transmission.

As a result, even after 1000 hours had elapsed, this optical fiber cable had a rate of decrease in the amount of light of 20 degrees, showing very little change (showing stable heat resistance and durability).

Comparative Examples 1 to 3 For comparison, Comparative Example 1 was prepared in the same manner as in Example 1 except that the composition of methyl methacrylate, α-methylstyrene, styrene, and maleic anhydride was as shown in Table 1. ~30 yuan fiber cable was obtained. The optical transmission performance and heat resistance durability of this original fiber cable were evaluated in comparison with Example 1, and are shown in Table 2.

As is clear from the results shown in Table 1 and Table 2, the optical transmission fiber of the present invention has a sufficient optical transmission loss to enable communication of optical signals of 10 ffl length, and its heat resistance and durability are also very excellent. The fibers had excellent flexibility and were easy to handle.On the other hand, Comparative Example 3 had poor heat resistance and durability, and the core and sheath peeled off very easily.

In Comparative Examples 1 and 2, the heat decomposition resistance of the sheath component polymer was poor, bubbles were observed in the sheath material of the fiber, and the light transmission performance was extremely poor.

Example 2. 3# and Comparative Examples 4 and 5 All of Example 1 and Comparative Examples 4 and 5 except that the composition ratio of the monomer mixture consisting of methyl methacrylate, styrene, and maleic anhydride was 9 as shown in Table 3 (similarly shown in Table 4). The results shown are obtained.

Table 3 α and β in Table 3 indicate the molar amounts of styrene and maleic anhydride, respectively.

Table 4 Light transmitting fibers in which the proportion of styrene/or maleic anhydride used is outside the range of the present invention have poor optical properties and extremely poor mechanical properties, making them difficult to use practically. Ta.

Example 4 The following monomers: Partial polymerization of methyl methacrylate (polymerization rate 7 to 8) 7000 J' Styrene 1800 J' Maleic anhydride 1200 P Methacrylic acid 100 P were mixed and dissolved, and bis-(3,5 ，
5-trimethylhexanoyl) peroxide 40F was added and polymerized at 80°C to prepare a sheath component copolymer. An original fiber cable was obtained in exactly the same manner as in Example 1 except that this copolymer was used. The obtained optical fiber cape only showed a decrease in the amount of transmitted light, and the adhesion between the core and sheath was extremely good, and the bending resistance was also excellent.

Effects of the Invention The optically transmitting fiber of the present invention is different from the conventional fiber containing polymethyl methacrylate as a core component and a fluorine-containing polymer as a sheath component, or alternatively, it has polystyrene as a core component and polymethyl methacrylate as a sheath component. It has significantly superior heat resistance and durability compared to conventional plastic optical fibers.

For this reason, the optically transmitting fiber of the present invention can be used for wiring in automobile engineering/engine rooms, and therefore has extremely high industrial significance and value as it can respond to the advancement of car electronics. be.

Claims (1)

[Scope of Claims] 1. (A150-98% by weight of methyl methacrylate monomer or partial polymer, (B) 1-40% by weight of styrene or vinyltoluene, (C11-2511-25
1% by weight than the refractive index of the sheath component copolymer coated with the sheath component made of a methacrylic resin obtained by copolymerizing a mixture consisting essentially of inic acid and the sheath component.
A light transmitting fiber comprising a core component made of a polymer having a high refractive index. 2. The light transmitting fiber according to claim 1, wherein the core component polymer is a transparent polymer having a heat distortion temperature of 70° C. or higher. 3. In the sheath component copolymer, the molar weight ratio of styrene/or vinyltoluene to maleic anhydride (α/β
) is within the range of 0.9 to 1.7.
Optical transmitting fiber described in Section 1. 4. The light transmitting fiber according to claim 1, wherein the core component polymer is an aromatic polycarbonate.