JP2964702B2 - Plastic optical fiber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic optical fiber which is excellent in all of translucency, heat resistance and mechanical properties and can be manufactured stably.

[0002]

2. Description of the Related Art A plastic optical fiber is composed of two kinds of polymers, a core component and a sheath component. As the core component, a polymer having excellent transparency and excellent weather resistance, such as polymethyl methacrylate, is generally used.
On the other hand, the sheath component keeps the light inside the core,
It is necessary that the refractive index be lower than that of the core component, and fluorine-containing polymers are widely used. Examples of the fluorine-containing polymer include vinylidene fluoride / tetrafluoroethylene copolymer (JP-B-63-67164) and hexafluoroacetone / vinylidene fluoride copolymer (JP-A-61-22305). Vinylidene fluoride copolymers are commonly used.

[0003] These vinylidene fluoride copolymers are:
Because of good compatibility with a polymer containing methyl methacrylate as a main component, an optical fiber using the sheath component as a sheath component has good interface adhesion to a core component and good mechanical properties. However, these vinylidene fluoride-based copolymers are all crystalline polymers and have a problem of poor transparency. In addition, since the glass transition temperature is low, an optical fiber using the same as a sheath component has a low heat resistance of about 70 ° C., and its use is limited.

[0004] Therefore, there has been proposed an optical fiber using the following fluorine-containing polymer as a sheath component having high transparency and high glass transition temperature. a: copolymer of fluoroalkyl methacrylate and methyl methacrylate (JP-B-43-8978, JP-A-62-265606), b: α-fluoroacrylate copolymer (JP-A-5959)
-227908), c: imidation reaction products such as the above a and b (Japanese Patent Application Laid-Open No. 61-1986)
121005, JP-A-61-246703),
Or acid anhydride (JP-A-60-184211), d: cyclic fluoropolymer (JP-A-63-261204)
No., JP-A-63-302303).

[0005] These fluorine-containing polymers have excellent transparency and a high glass transition temperature as compared with vinylidene fluoride-based copolymers, but have poor compatibility with polymers containing methyl methacrylate as a main component. Therefore, the optical fiber using these as the sheath component is superior in heat resistance to the optical fiber using the conventional vinylidene fluoride copolymer as the sheath component, but has insufficient interfacial adhesion with the core component. There is a problem that it is inferior in translucency and mechanical properties.

[0006]

SUMMARY OF THE INVENTION The main object of the present invention is to:
By improving the sheath component mainly composed of a fluorine-containing polymer having a high glass transition temperature so as to be a sheath component having excellent interfacial adhesion to the core component, not only heat resistance but also translucency and mechanical properties are improved. An object of the present invention is to provide a plastic optical fiber which is excellent in performance such as characteristics and can be stably manufactured.

[0007]

In order to achieve this object, a plastic optical fiber according to the present invention comprises a polymer (A) containing at least 60% by weight of methyl methacrylate units.
(Hereinafter abbreviated as methyl methacrylate polymer (A))
In an optical fiber having a core component consisting of: and a sheath component consisting of a polymer having a lower refractive index than the core component, the sheath component mainly comprises a fluorine-containing polymer (B) having a glass transition temperature of 70 ° C. or more. A fluorine-containing polymer composition containing 0.02 to 5% by weight of a block polymer (C) composed of a polymer (C1) containing 60% by weight or more of methyl methacrylate units and a fluorine-containing polymer (C2) as a component It is characterized by consisting of things.

That is, according to the present invention, the fluorine-containing polymer (B) having a high glass transition temperature, such as the above-mentioned ad, which is proposed as the sheath component, has a similarity or compatibility with the core component and the sheath component. 0.02 to 5% by weight of a block polymer (C) obtained by bonding polymers at least one by one polymer chain
The problem of the prior art could be solved by using a composition mixed with a small amount as a sheath component.

The methyl methacrylate polymer (A) as the core component is a polymer containing 60% by weight or more of a methyl methacrylate unit. For example, a methyl methacrylate homopolymer, a (meth) acrylic polymer containing methyl methacrylate as a main component, and the like. Methyl methacrylate-based copolymer obtained by copolymerizing acid ester, (meth) acrylic acid, substituted styrene, N-substituted maleimide, etc., or modified polymers such as glutaric anhydride and glutarimide obtained by polymerizing them Is mentioned.

Examples of the (meth) acrylate include methyl acrylate, ethyl methacrylate, butyl methacrylate, t-butyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, phenyl methacrylate, bornyl methacrylate, and adamantyl methacrylate. Examples of the substituted styrene include styrene, methyl styrene, and α-methyl styrene. Examples of the N-substituent in the N-substituted maleimide include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, t-butyl, hexyl, and cyclohexyl. A plurality of these copolymer components may be used, and a small amount of other components may be used. In addition, a stabilizer such as a thermal oxidation deterioration inhibitor may be contained in an amount that does not adversely affect the light transmittance.

The fluorine-containing polymer (B), which is the main component of the sheath component, is a fluorine-containing polymer having a glass transition temperature of 70 ° C. or higher. Examples thereof include a fluorine-containing polymer which is substantially colorless and transparent at a glass transition temperature of 70 ° C. or higher and whose compatibility with the methyl methacrylate polymer (A) as the core component is desired to be improved. It is not limited. a. Copolymer of fluoroalkyl methacrylate and methyl methacrylate b. α-fluoroacrylate copolymer c. Imidation reaction products such as the above a and b, acid anhydride d. Cyclic fluoropolymer

Among them, Equation 1

Embedded image (However, R1 H or F, R2 is CH ₃ or F,
m represents 1 or 2, and p represents an integer of 0 to 10. Or a polymer containing 60 to 100% by weight of a (fluoro) alkyl (meth) acrylate unit and 0 to 40% by weight of a methyl methacrylate unit represented by Modified polymers such as glutaric anhydride and glutarimide are effective.

The block polymer (C) blended in a small amount in the sheath component comprises a polymer (C1) containing 60% by weight or more of a methyl methacrylate unit (hereinafter abbreviated as a methyl methacrylate polymer (C1)) and a fluorine-containing polymer. Coalescing (C
2) is a polymer obtained by bonding at least one polymer chain at a time, and a homopolymer having only one polymer chain does not provide any desired effect contrary to the gist of the present invention. Conversely, the effect tends to decrease as the number of polymer chains bonded in the block polymer increases, so that the number of polymer chains bonded in the block polymer is preferably two or less each. Further, it is most preferable that one is a single polymer chain and the other is a single or double polymer chain.

The methyl methacrylate polymer (C1) forming one polymer chain of the block polymer (C) may be freely selected within the range of the methyl methacrylate polymer (A) forming the core component. However, in order to sufficiently improve the interfacial adhesion between the core component and the methyl methacrylate polymer (A), the same or similar polymer as the type of the methyl methacrylate polymer (A) used for the core component, Alternatively, it is preferable to select a polymer having good compatibility.

Similarly, the fluorine-containing polymer (C2) forming one polymer chain of the block polymer (C) may be freely selected within the range of the fluorine-containing polymer (B) forming the sheath component. Among them, a polymer containing a (fluoro) alkyl (meth) acrylate unit represented by the above formula 1 or a modified polymer such as glutaric anhydride or glutarimide obtained by polymerizing them is preferable. And a polymer containing 40 to 100% by weight of the (fluoro) alkyl (meth) acrylate unit and 0 to 60% by weight of a methyl methacrylate unit as a (co) polymer component, or a glutar obtained by polymerizing the polymer. It is preferably a modified polymer such as an acid anhydride and glutarimide. Further, it is preferable to select a polymer which is the same or similar to the kind of the fluorine-containing polymer (B) used for the sheath component, or a polymer having good compatibility.

The desired effect can be obtained by blending the block polymer (C) in an amount of 0.02 to 5% by weight with respect to the sheath component composition.
~ 3% by weight is preferred. If it is less than 0.02% by weight, it is difficult to obtain a sufficient effect. Conversely, if the content exceeds 5% by weight, not only the cost is increased, but also the excellent properties of the fluorine-containing polymer (B), which is the main component of the sheath component, are hindered, and the optical fiber is opaque and the light-transmitting property of the optical fiber is reduced. It is not suitable for the sheath component because it may reduce the content. The weight ratio of the respective polymer chains forming the block polymer (C) is preferably in the range of 1/4 to 4/1. Outside this range, the effect of improving the compatibility with the fluorine-containing polymer (B), which is the main component of the sheath component, or the interfacial adhesion with the methyl methacrylate polymer (A) as the core component becomes insufficient. The effect of improving the adhesion between the core and the sheath can be obtained by adding a small amount of the block polymer (C) to the core component. However, since the cleanness of the core component is impaired, the light transmittance deteriorates. Practically difficult to use.

Block polymers are generally described by A. A method of polymerizing a monomer of another polymer chain from a polymer of one polymer chain having a reactive group at a terminal (including a living polymerization method and an iniferter method). The block polymer (C) can be produced by any method such as a method of bonding a polymer of two kinds of polymer chains each having a reactive group at the terminal. A method in which a polymer is not easily formed is preferable.

The block polymer (C) thus obtained
Is mixed homogeneously with a fluorine-containing polymer (B) in the form of chips or flakes to form a polymer composition, which is used as a sheath component and co-extruded together with a core component methyl methacrylate polymer (A), An optical fiber may be manufactured. The optical fiber further includes polyethylene, polypropylene or a copolymer or blend thereof, an olefin-based polymer containing an organosilane group,
The cord can be coated with a resin such as ethylene-vinyl acetate, polyvinyl chloride, polyvinylidene fluoride, nylon resin, polyester resin, nylon elastomer, polyester elastomer or urethane.
Alternatively, after the core component alone is melt-extruded, the sheath component can be fused around the core component in a temperature range not lower than the glass transition temperature of the sheath component, and formed into a sheet. Alternatively, the core component can be extruded into a sea-island structure in which the core component forms an island and the sea component forms an ocean using a multi-core die.

[0019]

According to the present invention, the conventional fluorine-containing polymer (B) having a high glass transition temperature in the sheath component is modified by adding a small amount of a specific block polymer (C) as a modifier. It was able to solve the technical problem. That is, the sheath component fluorine-containing polymer (B)
Has poor adhesion to the methyl methacrylate polymer (A) used as a core component, but has excellent properties such as high transparency and high glass transition temperature. However, even when the fluorine-containing polymer (B) is the main component, a polymer (C1) that is the same or similar to the methyl methacrylate-based polymer (A), and a polymer that is the same or similar to the fluorine-containing polymer (B) A block polymer (C) obtained by bonding (C2) at least one polymer chain at a time,
Surprisingly, the above-mentioned drawbacks of the fluorine-containing polymer (B) can be compensated for by using a polymer composition blended in a small amount of 2 to 5% by weight as a sheath component to provide an optical fiber. Thus, an optical fiber having excellent properties such as optical properties and mechanical properties, and which can be manufactured stably can be obtained.

[0020]

EXAMPLES The abbreviations of the monomers used in the following examples and the details of their chemical compositions are as follows.

(1) Fluoroalkyl methacrylate 5FM:

Embedded image (2) Fluoroalkyl methacrylate 4FM:

Embedded image

An example of a method for synthesizing the block polymer (C) will be described below. Reference Example 1 Methylaluminum triphenylporphyrin complex 0.25 parts by weight Visible light was applied to 70 parts by weight of benzotrifluoride at −40 ° C., and 35 parts by weight of methyl methacrylate and 0.05 part by weight of trimethylaluminum were sequentially added thereto. After the reaction for 5 hours, 30 parts by weight of 5FM, 15 parts by weight of 4FM, 20 parts by weight of methyl methacrylate, and 130 parts by weight of benzotrifluoride were further added and reacted for 2 hours. Diluting the polymer mixture with benzotrifluoride and reprecipitating in methanol;
The precipitate was vacuum-dried at 100 ° C. for 48 hours to obtain a block polymer composed of polymethyl methacrylate / fluorine-containing polymer.

Reference Example 2 The charge composition was as follows: during polymerization of the first polymerization chain, 65 parts by weight of methyl methacrylate 130 parts by weight of benzotrifluoride, during polymerization of the second polymerization chain, 5 FM
A polymer was obtained in the same manner as in Reference Example 1, except that 15 parts by weight, 4 FM, 10 parts by weight, methyl methacrylate, 10 parts by weight, and benzotrifluoride, 70 parts by weight .

Reference Example 3 A reference example was made except that the charged composition was changed to 55 parts by weight of pentafluoropropyl α-fluoroacrylate 10 parts by weight of methyl α-fluoroacrylate 130 parts by weight of benzotrifluoride at the time of polymerization of the second polymer chain. A polymer was obtained in the same manner as in Example 1. Hereinafter, the present invention will be described more specifically with reference to Examples using the block polymers obtained in Reference Examples 1 to 3 .

The evaluation method of the optical fiber was performed as follows. The translucency was measured by a normal cutback method, and evaluated with a loss value of 650 nm.
Heat resistance was evaluated by measuring the amount of emitted light when using a red LED as a light source after heating at 90 ° C. for 500 hours in an oven with a 10-meter test length and comparing it with an untreated product. did. The bending characteristics were continuously bent 180 degrees at a bending radius of 5 mm under a load of 700 g, and the number of times until breaking was measured five times, and the average value was evaluated. The production stability of the optical fiber was evaluated based on the average wire diameter variation width.

Example 1 The block polymer of Reference Example 1 was prepared by using a 5FM / 4FM / methyl methacrylate copolymer (copolymerization ratio (% by weight): 5
0/20/30, refractive index 1.41 , glass transition temperature 84
° C) . This is used as a sheath component, and polymethyl methacrylate (100%, refractive index 1.
Using 49) as a core component, in a continuous polymerization / spinning apparatus for ordinary polymethyl methacrylate-based plastic optical fiber, it is melt-co-extruded at 240 ° C. to perform composite spinning, and then 2
An optical fiber was obtained by stretching the optical fiber twice. The outer diameter of the obtained optical fiber was 1000 μm, and the thickness of the sheath component was 10 μm. The variation in the diameter of the optical fiber is 18 μm, and the light transmission is 1 μm.
The heat resistance was 28 dB / km, the light quantity retention rate was 98%, and the bending characteristics were 1150 breaks.

Example 2 An optical fiber was obtained in the same manner as in Example 1 except that the content of the block polymer in Reference Example 1 was set to 1.0% by weight based on the entire sheath component. The variation width of the obtained optical fiber is 1
9 μ, light transmissivity was 127 dB / km, heat resistance was 98% light retention, and bending characteristics were 1210 breaks.

Example 3 An optical fiber was obtained in the same manner as in Example 1, except that the content of the block polymer in Reference Example 2 was set to 1.0% by weight based on the total sheath component. The variation width of the obtained optical fiber is 1
9 μ, light transmissivity was 126 dB / km, heat resistance was 99%, and bending characteristics were 1280 breaks.

Comparative Example 1 An optical fiber was obtained in the same manner as in Example 1 except that the block polymer was not blended. The obtained optical fiber had a line diameter fluctuation width of 20 μ, a light transmissivity of 135 dB / km, a heat resistance of 97% in light quantity retention, and a bending characteristic of 860 breaks.

Comparative Example 2 An optical fiber was obtained in the same manner as in Example 1 except that the content of the block polymer in Reference Example 1 was 10% by weight based on the total sheath component. The fluctuation width of the obtained optical fiber is 23.
μ, transmissivity: 266 dB / km, heat resistance: light intensity holding ratio, 9
6%, the bending characteristics were Tsu Der breaking number of times 1460 times.

Comparative Example 3 The sheath component was a vinylidene fluoride / tetrafluoroethylene copolymer (copolymerization ratio (% by weight): 80/20, refractive index 1.40 , glass transition temperature: -35 to -38 ° C. ) An optical fiber was obtained in the same manner as in Example 1 except that only the above was used.
The obtained optical fiber has a wire diameter variation width of 14 μ and a light transmittance of 1
35 dB / km, heat resistance was 45%, and the bending characteristic was 1880 breaks.

Example 4 The block polymer of Reference Example 4 was prepared using a pentafluoropropyl α-fluoroacrylate / methyl α-fluoroacrylate copolymer (copolymerization ratio (% by weight): 80/20,
A refractive index of 1.39 , a glass transition temperature of 113 ° C. ) and 2.0% by weight of a sheath component were mixed.
An optical fiber was obtained in the same manner as in Example 1, except that an adamantyl methacrylate copolymer (copolymerization ratio (% by weight): 70/30, refractive index 1.51) was used as a core component. The obtained optical fiber has a wire diameter variation width of 21 μ and a light transmittance of 25.
8 dB / km, the heat resistance was 102%, and the bending characteristic was 1,260 times the number of breaks.

Comparative Example 4 An optical fiber was obtained in the same manner as in Example 4 except that the block polymer was not blended. The obtained optical fiber had a variation in wire diameter of 20 μm, a light transmittance of 273 dB / km, a heat resistance of 101%, and a bending characteristic of 850 breaks.

[0034]

The optical fiber of the present invention has a higher heat resistance than the conventional optical fiber having a sheath component of a fluorine-containing polymer (B) having a high glass transition temperature and poor compatibility with the core component. While maintaining, the interface adhesion between the core component and the sheath component is improved, and the mechanical properties such as light transmission and bending characteristics are improved, and stable production is possible.

Claims (3)

(57) [Claims] (1) 60% by weight of methyl methacrylate unit
In an optical fiber having a core component composed of the polymer (A) and a sheath component composed of a polymer having a lower refractive index than the core component, the sheath component has a glass transition temperature of 70.
A fluorine-containing polymer (B) at a temperature of at least ° C as a main component, and
A fluorine-containing polymer composition containing 0.02 to 5% by weight of a block polymer (C) comprising a polymer (C1) containing 60% by weight or more of methyl methacrylate units and a fluorine-containing polymer (C2) A plastic optical fiber, comprising: 2. The fluorine-containing polymer (B) constituting the main component of the sheath component is represented by the following formula 1. (However, R1 H or F, R2 is CH ₃ or F,
m represents 1 or 2, and n represents an integer of 0 to 10. Wherein the (fluoro) alkyl (meth) acrylate unit represented by the formula (1) is 60 to 100% by weight and the methyl methacrylate unit is 0 to 40% by weight as a (co) polymer component. The plastic optical fiber according to claim 1, wherein 3. A fluorine-containing polymer (C2) forming a polymer chain of the block polymer, wherein the (fluoro) alkyl (meth) acrylate unit represented by the formula 1 is 40 to 10
0% by weight, and 0-60
2. The plastic optical fiber according to claim 1, wherein said plastic optical fiber is a polymer containing at least one weight% as a (co) polymerization component.