JPH04358104A - Plastic optical fiber - Google Patents

Abstract

PURPOSE:To obtain the plastic optical fiber which has excellent performances of not only heat resistance but light transmittability and mechanical characteristics as well and can be stably produced by improving the fluorinated polymer to be used as a sheath component to improve the boundary adhesion to a core component. CONSTITUTION:The plastic optical fiber is constituted by using a polymer essentially consisting of methyl methacrylate as the core component and a compsn. which consists essentially of the fluorinated polymer having 70 deg.C glass transition temp. and is compounded with 0.02 to 5wt.% block polymer bonded with at least one each of the polymer chains of the polymers identical to or analogous with two kinds of these polymers as the sheath component.

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 that has excellent light transmittance, heat resistance, and mechanical properties and can be stably manufactured.

0002

2. Description of the Related Art Plastic optical fibers are composed of two types of polymers: a core component and a sheath component. Polymers with excellent transparency and good weather resistance, such as polymethyl methacrylate, are generally used as the core component. On the other hand, the sheath component is used to trap light inside the core.
It needs to have a lower refractive index than the core component, and fluorine-containing polymers are widely used.

As the fluorine-containing polymer, vinylidene fluoride/tetrafluoroethylene copolymer (Japanese Patent Publication No. 6
Vinylidene fluoride copolymers such as hexafluoroacetone/vinylidene fluoride copolymer (Japanese Patent Application Laid-Open No. 61-22305) are generally used.

These vinylidene fluoride copolymers are
Since it has good compatibility with a polymer whose main component is methyl methacrylate, an optical fiber using it as a sheath component has good interfacial adhesion with the core component and good mechanical properties. However, all of these vinylidene fluoride copolymers are crystalline polymers and have a problem of poor transparency. Furthermore, since the glass transition temperature is low, optical fibers using it as a sheath component have a low heat resistance of about 70° C., and their uses are limited.

[0005] Therefore, an optical fiber using the following fluorine-containing polymer as a sheath component, which has high transparency and a high glass transition temperature, has been proposed.

[0006] a: Copolymer of fluoroalkyl methacrylate and methyl methacrylate (Japanese Patent Publication No. 43-8
No. 978, Japanese Unexamined Patent Publication No. 62-265606), b:
α-Fluoroacrylate copolymer (JP-A-59-2
27908), c: imidization reaction products such as a and b above (Japanese Patent Laid-Open Publication No. 6
1-121005, JP-A-61-246703), or acid anhydride (JP-A-60-184211)
, d: cyclic fluoropolymer (JP-A-63-261204
No., Japanese Unexamined Patent Publication No. 63-302303).

These fluorine-containing polymers have excellent transparency and a high glass transition temperature compared to vinylidene fluoride copolymers, but have good compatibility with polymers whose main component is methyl methacrylate. do not have. Therefore, while optical fibers using these as sheath components have superior heat resistance compared to optical fibers that use conventional vinylidene fluoride copolymers as sheath components, they do not have sufficient interfacial adhesion with the core component. There are problems with poor translucency, mechanical properties, etc.

[0008]

[Problem to be Solved by the Invention] The main purpose of the present invention is to
By improving the sheath component, which is mainly composed of a fluorine-containing polymer with a high glass transition temperature, so that it has excellent interfacial adhesion with the core component, it not only has heat resistance but also has excellent translucency and mechanical properties. It is an object of the present invention to provide a plastic optical fiber that has excellent performance such as characteristics and can be manufactured stably.

[0009]

[Means for Solving the Problems] In order to achieve this object, the plastic optical fiber of the present invention is made of a polymer (A) containing 60% by weight or more of methyl methacrylate units (hereinafter referred to as methyl methacrylate units). An optical fiber having a core component made of a polymer (A)) and a sheath component made of a polymer having a lower refractive index than the core component, wherein the sheath component has a glass transition temperature of 70°C or higher. Fluorine-containing polymer (B
) and 6 methyl methacrylate units.
A block polymer (C) consisting of a polymer (C1) containing 0% by weight or more and a fluorine-containing polymer (C2) is
It is characterized by consisting of a fluorine-containing polymer composition containing 2 to 5% by weight.

That is, the present invention provides a fluorine-containing polymer (B) having a high glass transition temperature, such as the above-mentioned a to d, which has been proposed as a sheath component, and which is similar to or compatible with the core component and sheath component. 0.02 to 5% by weight of a block polymer (C) formed by bonding polymers together at least one polymer chain at a time.
The problems of the prior art could be solved by using a composition containing a small amount of the same as the sheath component.

The methyl methacrylate polymer (A) constituting the core component is a polymer containing 60% by weight or more of methyl methacrylate units, such as methyl methacrylate units.
methacrylate-based copolymers, which are mainly composed of methyl methacrylate and copolymerized with (meth)acrylic acid esters, (meth)acrylic acid, substituted styrene, N-substituted maleimide, etc. Alternatively, modified polymers such as glutaric anhydride, glutarimide, etc., which are obtained by polymerizing these materials, may be used.

Examples of (meth)acrylic acid esters include methyl acrylate, ethyl methacrylate, butyl methacrylate, t-butyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, and phenyl methacrylate. Examples include ester, bornyl methacrylate, and adamantyl methacrylate.

Examples of the substituted styrene include styrene, methylstyrene, and α-methylstyrene.

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 copolymerization components may be used, and a small amount of components other than these may also be used. Further, a stabilizer such as a thermal oxidative deterioration inhibitor may be included in an amount that does not adversely affect the translucency.

Fluorine-containing polymer (which is the main component of the sheath component)
B) is a fluorine-containing polymer with a glass transition temperature of 70°C or higher, such as the polymers a to d (below) mentioned above; The fluorine-containing polymer is not limited to this as long as it is transparent and desired to improve compatibility with the methyl methacrylate polymer (A) as the core component.

a. Copolymer of fluoroalkyl methacrylate and methyl methacrylate b. α-fluoroacrylate copolymer c. a, b above
Imidization reaction products such as acid anhydrides d. Among the cyclic fluoropolymers, formula 1

[0018]

[Case 2]

(However, R1 is H or F, R2 is CH3 or F, m is 1 or 2, and p is an integer from 0 to 10.)
60 to 100% by weight of meth)acrylate units, and
A polymer containing 0 to 40% by weight of methyl methacrylate units as a (co)polymerization component, or a modified polymer such as glutaric anhydride or glutarimide obtained by polymerizing these polymers are effective.

Block polymer mixed in a small amount in the sheath component
(C) is a polymer (C1) containing 60% by weight or more of methyl methacrylate units (hereinafter abbreviated as methyl methacrylate polymer (C1)) and a fluorine-containing polymer (C2).
) are bonded together in at least one polymer chain, and a homopolymer with only one polymer chain is contrary to the spirit of the present invention, and the desired effect cannot be obtained at all. Conversely, the effect tends to decrease as the number of polymer chains bonded in the block polymer increases, so it is preferable that the number of bonded polymer chains in the block polymer is equal to or less than one double chain. Furthermore, it is most preferable that one of them is a monopolymer chain and the other is a monopolymer chain or a double chain. The methyl methacrylate polymer (C1) forming the monopolymerized chain of the block polymer (C) is the methyl methacrylate polymer (C1) forming the core component.
It may be freely selected within the range of the polymer (A). However, the core component methyl methacrylate polymer (
In order to sufficiently improve the interfacial adhesion with A), it is necessary to use a polymer that is the same or similar to the methyl methacrylate polymer (A) used for the core component, or a polymer with good compatibility. It is preferable to select

Similarly, the fluorine-containing polymer (C2) forming the monopolymerized chain of the block polymer (C) may be selected freely within the range of the fluorine-containing polymer (B) forming the sheath component. Among them, polymers containing (fluoro)alkyl (meth)acrylate units represented by the above formula 1, or glutaric anhydride obtained by polymerizing them,
Preferably, it is a modified polymer such as glutarimide, and further, 40 to 100% by weight of the (fluoro)alkyl (meth)acrylate unit and 0 to 60% by weight of the methyl methacrylate unit are (co)polymerized. It is preferable to use a polymer contained as a component or a modified polymer such as glutaric anhydride or glutarimide obtained by polymeric reaction with the polymer. Furthermore, it is preferable to select a polymer that is the same or similar to the fluorine-containing polymer (B) used for the sheath component, or a polymer that has good compatibility.

The desired effect can be obtained by blending this 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 sufficient effects. On the other hand, if it exceeds 5% by weight, not only will the cost increase, but the excellent properties of the fluorine-containing polymer (B), which is the main component of the sheath component, will be inhibited, and the optical fiber will become cloudy and the translucency of the optical fiber will be impaired. It is not suitable as a sheath component as it may reduce the

The weight ratio of each polymer chain constituting this 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), which is the core component, is insufficient. becomes.

Although it is possible to improve the adhesion between the core and sheath by adding a small amount of this block polymer (C) to the core component, the cleanliness of the core component is impaired and the transparency is reduced. It is practically difficult to use because the optical property deteriorates.

Block polymers are generally A. A method of polymerizing monomers of other polymer chains from a polymer of one polymer chain having a reactive group at the end (living polymerization method, iniferter polymerization method)
(including laws) B. This block polymer (C) can be produced by a method such as combining two types of polymer chains each having a reactive group at the end.Although this block polymer (C) can also be produced by any method, A method that does not easily produce a homopolymer is preferred.

Block polymer (C) thus obtained
, chips or flakes of fluorine-containing polymer (B
) to form a polymer composition, which is used as the sheath component, and the core component methyl methacrylate polymer (A
) may be melted and co-extruded to produce an optical fiber.

This optical fiber may further contain polyethylene, polypropylene or a copolymer or blend thereof, an olefinic polymer containing an organic silane group, ethylene-vinyl acetate, polyvinyl chloride, polyvinylidene fluoride, or nylon resin. It can be coated with resin such as polyester resin, nylon elastomer, polyester elastomer, or urethane to form a cord.

It is also possible to melt and extrude only the core component and then fuse the sheath component around the core component in a temperature range equal to or higher than the glass transition temperature of the sheath component to form a sheet. Alternatively, a multicore die may be used to extrude into a sea-island structure in which the core component forms an island and the sheath component forms a sea.

[0029]

[Function] In the present invention, by adding a small amount of a specific block polymer (C) as a modifier to the conventional fluorine-containing polymer (B) having a high glass transition temperature in the sheath component, This method was able to solve the problems of the prior art.

That is, the fluorine-containing polymer (B) as the sheath component is the methyl methacrylate polymer (B) used as the core component.
Although the interfacial adhesion with A) is not good, it has excellent properties such as high transparency and a high glass transition temperature. However, even if the fluorine-containing polymer (B) is the main component, a polymer (C1) that is the same or similar to the methyl methacrylate polymer (A), and a polymer that is the same or similar to the fluorine-containing polymer (B) A block polymer (C) formed by bonding at least one polymer chain of polymers (C2) with 0.02
Surprisingly, the above-mentioned drawbacks of the fluorine-containing polymer (B) can be compensated for by making an optical fiber with a polymer composition containing a small amount of ~5% by weight as a sheath component. This makes it possible to obtain an optical fiber that has excellent properties such as strength and mechanical properties, and can be manufactured stably.

[0031]

[Examples] The abbreviations and chemical compositions of monomers used in the following examples are as follows.

(1) Fluoroalkyl methacrylate
G 5FM:

[0033]

[Chemical formula 3]

(2) Fluoroalkyl methacrylate
G 4FM:

[0035]

[C4]

An example of the method for synthesizing block polymer (C) is shown below.

Reference Example 1 Methylaluminum triphenylporphyrin complex
0.25 parts by weight benzotrifluoride 70
Irradiate the weight part with visible light at -40°C to obtain methyl methacrylate 3
5 parts by weight trimethylaluminum
0.05 parts by weight were added one after another, and after reacting for 2 hours,
More 5FM
30 parts by weight 4FM
15 parts by weight Methyl methacrylate 20 parts by weight Benzotrifluoride 130
Parts by weight were added and the reaction was carried out for 2 hours. The polymer mixture was diluted with benzotrifluoride and reprecipitated in methanol, and the precipitate was vacuum dried at 100°C for 48 hours.
A block polymer consisting of polymethyl methacrylate/fluorine-containing polymer was obtained.

Reference Example 2 The charging composition was changed to methyl methacrylate 6 during polymerization of the first polymer chain.
5 parts by weight benzotrifluoride
When polymerizing 130 parts by weight of the second polymer chain, 5FM
15 parts by weight 4FM
10 parts by weight Methyl methacrylate 10 parts by weight Benzotrifluoride 7
A polymer was obtained in the same manner as in Reference Example 1 except that the amount was 0 parts by weight.

Reference Example 3 When the first polymer chain was polymerized, the charging composition was changed to: methyl methacrylate 1
0 parts by weight benzotrifluoride
When polymerizing 20 parts by weight of the second polymer chain, 5FM
45 parts by weight 4FM
20 parts by weight Methyl methacrylate 25 parts by weight Benzotrifluoride 180
A polymer was obtained in the same manner as in Reference Example 1 except that the parts by weight were changed.

Reference Example 4 The charging composition was changed to the following when polymerizing the second polymer chain: pentafluoropropyl α-fluoroacrylate
55 parts by weight Methyl α-fluoroacrylate 10 parts by weight Benzotrifluoride 1
A polymer was obtained in the same manner as in Reference Example 1 except that the amount was 30 parts by weight.

The present invention will be explained in more detail below using examples using the block polymers obtained in Reference Examples 1 to 4 above.

The optical fibers were evaluated as follows.

The light transmittance was measured by the usual cutback method and evaluated by the loss value at 650 nm.

[0044] Heat resistance: 10m test length, oven, 90%
After heating at ℃ for 500 hours, the amount of emitted light was measured when a red LED was used as a light source, and evaluation was made based on the light amount retention rate determined by comparing with an untreated product.

The bending properties were evaluated by continuously bending 180 degrees at a bending radius of 5 mm under a load of 700 g, measuring the number of times until breakage five times, and using the average value.

Furthermore, the manufacturing stability of the optical fiber was evaluated based on the variation range of the average wire diameter.

Example 1 The block polymer of Reference Example 1 was mixed with 5FM/4FM/methyl methacrylate copolymer (copolymerization ratio (weight %): 5
0/20/30, refractive index 1.41) and 0.3% by weight. This is used as a sheath component, and polymethyl methacrylate (100%, refractive index 1.49) is used as a core component, and 240 The composite was spun by melt coextrusion at ℃, and then stretched twice to obtain an optical fiber.

The outer diameter of the obtained optical fiber was 1000μ,
The thickness of the sheath component was 10μ.

[0049] Furthermore, the diameter variation width of the optical fiber is 18
μ, translucency is 128dB/km, heat resistance is light intensity retention rate 9
8%, and the bending property was 1150 times at break.

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 relative to the total sheath component was 1.0% by weight.

The diameter variation width of the obtained optical fiber was 19μ.
, translucency is 127dB/km, heat resistance is light intensity retention rate 98
%, and the bending properties were 1210 times at break.

Example 3 An optical fiber was obtained in the same manner as in Example 1, except that the content of the block polymer of Reference Example 2 relative to the total sheath component was 1.0% by weight.

The diameter variation width of the obtained optical fiber was 19μ.
, translucency is 126dB/km, heat resistance is light intensity retention rate 99
%, and the bending properties were broken 1280 times.

Comparative Example 1 An optical fiber was obtained in the same manner as in Example 1, except that no block polymer was blended.

The diameter variation range of the obtained optical fiber was 20μ.
, translucency is 135dB/km, heat resistance is light intensity retention rate 97
%, and the bending properties were broken 860 times.

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 relative to the total sheath component was 10% by weight.

The diameter variation width of the obtained optical fiber was 23μ.
, translucency is 266dB/km, heat resistance is light intensity retention rate 96
%, and the bending properties were broken 1460 times.

Comparative Example 3 An optical fiber was obtained in the same manner as in Example 1, except that the block polymer of Reference Example 3 was used.

The diameter variation range of the obtained optical fiber was 20μ.
, translucency is 134dB/km, heat resistance is light intensity retention rate 97
%, and the bending properties were broken 900 times.

Comparative Example 4 The sheath component was vinylidene fluoride/tetrafluoroethylene copolymer (copolymerization ratio (wt%): 80/20, refractive index 1)
．． An optical fiber was obtained in the same manner as in Example 1 except that only 40) was used.

The diameter variation width of the obtained optical fiber was 14μ.
, Translucency is 135dB/km, Heat resistance is light intensity retention rate 45
%, and the bending properties were 1880 times at break.

Example 4 The block polymer of Reference Example 4 was mixed with pentafluoropropyl α-fluoroacrylate/methyl α-fluoroacrylate copolymer (copolymerization ratio (wt%): 80/20,
Methyl methacrylate/adamantyl methacrylate was mixed using a sheath component with a refractive index of 1.39) and 2.0% by weight.
An optical fiber was obtained in the same manner as in Example 1, except that a copolymer (copolymerization ratio (weight %): 70/30, refractive index 1.51) was used as the core component.

The diameter variation range of the obtained optical fiber was 21μ.
, translucency is 258dB/km, heat resistance is light intensity retention rate 10
2%, and the bending property was 1260 times at break.

Comparative Example 5 An optical fiber was obtained in the same manner as in Example 4, except that no block polymer was blended.

The diameter variation range of the obtained optical fiber was 20μ.
, translucency is 273dB/km, heat resistance is light intensity retention rate 10
1%, and the bending property was 850 times at break.

[0066]

[Effects of the Invention] Compared to conventional optical fibers whose sheath component is a fluorine-containing polymer (B) that has a high glass transition temperature and poor compatibility with the core component, the optical fiber of the present invention has excellent heat resistance. In addition, the interfacial adhesion between the core component and the sheath component is improved, mechanical properties such as translucency and bending properties are improved, and stable production is possible.

Claims (3)

[Claims] 1. An optical fiber having a core component made of a polymer (A) containing 60% by weight or more of methyl methacrylate units, and a sheath component made of a polymer having a refractive index lower than that of the core component. , the sheath component has a glass transition temperature of 7
A block polymer consisting of a polymer (C1) and a fluorine-containing polymer (C2) whose main component is a fluorine-containing polymer (B) having a temperature of 0°C or higher and containing 60% by weight or more of methyl methacrylate units. A plastic optical fiber comprising a fluorine-containing polymer composition containing 0.02 to 5% by weight of C). 2. The fluorine-containing polymer (B) which constitutes the main component of the sheath component has the formula 1: (wherein R1 is H or F, R2 is CH3 or F, m is 1 or 2, and n represents an integer from 0 to 10.) Contains 60 to 100% by weight of (fluoro)alkyl (meth)acrylate units and 0 to 40% by weight of methyl methacrylate units as (co)polymerization components. 2. The plastic optical fiber according to claim 1, wherein the plastic optical fiber is a polymer of 3. The fluorine-containing polymer (C2) constituting the polymer chain of the block polymer contains 40 to 1 (fluoro)alkyl (meth)acrylate unit represented by the formula 1.
00% by weight and 0 to 6 methyl methacrylate units
2. The plastic optical fiber according to claim 1, wherein the plastic optical fiber is a polymer containing 0% by weight as a (co)polymerization component.