JPH01233404A - Plastic optical fiber and cord having excellent light transmittability and heat resistance - Google Patents

Abstract

PURPOSE:To obtain a plastic optical fiber having excellent mechanical characteristics such as flexibility, high numerical aperture and excellent light transmittability and heat resistance by using a methyl methacrylate polymer as a fiber component and a copolymer of vinylidene fluoride and tetrafluoro- ethylene as a sleeve component. CONSTITUTION:The polymer essentially consisting of the methyl methacrylate is used as the fiber component and the copolymer of the vinylidene fluoride and tetrafluoroethylene contg. 81-85mol.% vinylidene fluoride is used as the sleeve component. The polymer essentially consisting of the methyl methacrylate refers to polymethyl methacrylate or a polymethyl methacrylate copolymer contg. <=5wt.% other copolymer components and the copolymer of the vinylidene fluoride and tetrafluoroethylene is a binary copolymer contg. 81-85mol.% vinylidene fluoride and 19-15mol.% tetrafluoroethylene. The plastic optical fiber having the excellent mechanical characteristics such as flexibility, the high numerical aperture and the excellent light transmittability is thereby obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to plastic optical fibers and cords used in short-range communication applications such as various industrial sensors and data links.

[Prior Art] Conventionally, a plastic optical fiber having a core component of polymethyl methacrylate and a sheath component of a fluorine-containing polymer containing fluorinated methacrylate as a main component has been proposed as a plastic optical fiber with excellent light transmission properties. ing. (Unexamined Japanese Patent Publication No. 58-7602 @ Publication) However, the plastic optical fiber whose sheath component is a fluorine-containing polymer whose main component is fluorinated methacrylate has the problems of somewhat poor flexibility and a small numerical aperture. have. In addition, as a plastic optical fiber with excellent flexibility and a high numerical aperture, we have developed a plastic optical fiber whose sheath component is a copolymer of vinylidene fluoride and tetrafluoroethylene containing 60 to 80 mol% of vinylidene fluoride (Unexamined Japanese Patent Publication No. (Japanese Patent Publication No. 50-20737) has been proposed, but it has a problem of inferior optical transmission properties and heat resistance compared to plastic optical fibers using a fluorinated acrylate sheath component.

[Problems to be Solved by the Invention] The purpose of the present invention is to solve the above-mentioned drawbacks of conventional optical fibers, have excellent mechanical properties such as flexibility, have a high numerical aperture, and have optical transmission properties. Another object of the present invention is to provide plastic optical fibers and cords with excellent heat resistance.

[Means for Solving the Problems] In order to achieve the above object, the present invention has the following features.

(1) The core component is a polymer whose main component is methyl methacrylate, and the sheath component is a polymer containing vinylidene fluoride of 81 to 85%.
An optical transmission body and a plastic optical fiber with excellent heat resistance, characterized by being made of a copolymer of vinylidene fluoride and tetrafluoroethylene containing mol%.

(2) A core-sheath composite structure in which the core component is a polymer mainly composed of methyl methacrylate and the sheath component is a copolymer of vinylidene fluoride and tetrafluoroethylene containing 81 to 85 mol% of vinylidene fluoride. An optical transmission body and a plastic optical fiber cord having excellent heat resistance, characterized in that the sheath material is polyethylene, polypropylene, or a copolymer thereof.

(3) Claim obtained by a process in which spinning and drawing are directly connected (1)
) listed plastic optical fibers.

(4) Stretching ratio 1.5 to 3 times, winding speed V 5/d
The plastic optical fiber according to claim <1) obtained under the conditions of <VS20/d2 and in a process directly connected to spinning and drawing.

V: Winding speed m/min d: Fiber diameter mm (5) The plastic optical fiber according to claim (2), wherein the plastic optical fiber having a core-sheath composite structure is obtained by a direct spinning/drawing process. code.

(6) The plastic optical fiber having a core-sheath composite structure has a stretching ratio of 1.5 to 3 times and a winding speed V of 5/d<V<
The plastic optical fiber cord according to claim 2, which is obtained by a direct spinning/drawing process under conditions of 30/d2.

V: Winding speed m/min d: Fiber diameter mm The present invention will be explained in detail below.

The polymer mainly composed of methyl methacrylate in the present invention is polymethyl methacrylate or a polymethyl methacrylate copolymer containing 5% by weight or less of other copolymer components.

Copolymerization components include aliphatic methacrylates or acrylates such as ethyl methacrylate, methyl acrylate, and ethyl acrylate; methacrylates having alicyclic hydrocarbon groups such as bornyl methacrylate and adamantyl methacrylate; aliphatic maleimides such as isopropyl maleimide and 5ec-butyl maleimide; can be mentioned.

The copolymer of vinylidene fluoride and tetrafluoroethylene as used in the present invention is a binary copolymer containing 81 to 85 mol% of vinylidene fluoride and 19 to 15 mol% of tetrafluoroethylene.

If the content of vinylidene fluoride exceeds 85 mol%, the optical transmission properties will be lowered, and the heat resistance and adhesiveness will also be deteriorated.

Conventionally, copolymers containing 80 mol% or less of vinylidene fluoride have a low refractive index, good adhesion to polymethyl methacrylate, and good thermal stability, as described in JP-A-50-20737. It has the characteristics that vinylidene fluoride is 80%
It was thought that if the amount exceeds 90 mol%, for example, 90 mol% or more, crystallization tends to occur, resulting in a decrease in optical transmission properties and deterioration in adhesiveness and heat resistance.

However, it is surprising that copolymers containing 81 to 85 mol% vinylidene fluoride have a smaller increase in refractive index than copolymers containing 80 mol% or less, and almost no deterioration in mechanical properties and adhesive properties. It is possible to obtain an optical fiber with improved heat resistance and excellent optical transmission properties.

Conventionally, the heat resistance of plastic optical fibers and cords is
In the case of a polymer whose core component is methyl methacrylate as a main component, it is limited by heat-induced deformation and contraction of the constituent components.
It was limited by the heat resistance of the sheath component polymer, and was in the range of 70°C to 85°C. In the case of plastic optical fibers that use vinylidene fluoride-based polymers, it is thought that if the vinylidene fluoride-based polymer is held at temperatures higher than 70'C, crystallization of the vinylidene fluoride-based polymer will progress and become cloudy, resulting in a decrease in optical transmission properties. It will be done.

A copolymer containing 81 to 85 mol% of vinylidene fluoride, as in the present invention, undergoes slow crystallization even at high temperatures of 80 to 90°C, so there is only a slight decrease in light transmittance, and the copolymer can be heated at higher temperatures than conventional copolymers. It can be used in

The preferred structure of the plastic optical fiber and cord in the present invention is that the core/sheath ratio is 10/1 or more, the fiber diameter is 10μ to 3000μ, and the cord diameter is 1.0 to 5.5μ. Q
The size is mm.

Of course, it may be a cord made of a plurality of fibers covered with a sheath material. For optical fibers and cords with a fiber diameter of 500 μm or less, the effect of improving optical transmission properties is particularly large, and for fiber diameters of 500 μm or more, the effect of improving mechanical properties and heat resistance is remarkable.

[Examples] Hereinafter, the present invention will be explained in more detail with reference to Examples.

In addition, the evaluation of light transmittance in the examples was measured as follows.

The light from the tungsten lamp is split by a diffraction grating, focused by a lens, and then enters one end of a 20-30m optical fiber. The light emitted from the other end is detected as optical power by a photodiode. Next, the optical fiber is cut at a distance of about 2 m from the input end while the input end is fixed, and measurements are repeated in the same manner, using the so-called cutback method, and the light transmission loss of the optical fiber is calculated according to the following formula.

Loss value (dB/m) = (Ps-Pr)/(ms-Lr) ・103L: Fiber length (m> P: Optical power value (dBm) S: Sample fiber r: Cutback reference fiber Heat resistance was measured by the following method.

The plastic optical fiber used for measurement was heated in a hot air dryer held at each temperature for a predetermined period of time, and the translucency of the initial and heated bond was measured according to the above method, and the values were compared. After heating for 500 hours, the initial translucency was 80.
The maximum temperature at which % can be maintained was defined as the heat-resistant temperature.

Analytica ChimiC containing vinylidene fluoride, a copolymer of vinylidene fluoride and tetrafluoroethylene
The 19F xMR method described in aActa, 189, 101-116 (1986) was used.

Fiber flexibility was measured by a conventional method and expressed as the minimum bending diameter at break.

[Example] Example 1 Polymethyl methacrylate obtained by continuous bulk polymerization was used as a core component, and a copolymer containing 82 mol% of vinylidene fluoride and 18 mol% of tetrafluoroethylene was used as a sheath component, and a 240 mm polyester resin was produced by a process directly coupled to spinning and stretching. Composite spinning at °C, stretching ratio 2.1, stretching temperature 155 °C1 Heat treatment after stretching 155
°C 1 fiber with a diameter of 1000μ with a sheath component of 10μ
It was wound up at a speed of 0 m/min. The obtained fiber had good physical properties such as a light transmittance of 150 d13/m, a heat resistance temperature of 90° C., and a flexibility of 2 mm or less.

Examples 2 to 4, Comparative Examples 1 to 2 The physical properties of fibers obtained by carrying out the same procedure as in Example 1 by changing the composition of the sheath component and the spinning/drawing conditions are summarized in a table.

Example 5, Comparative Example 3 Using the fibers of Example 1 and Comparative Example 1, a cord with a diameter of 2.2 mm was manufactured using medium density polyethylene, and the physical properties of the cord were evaluated. The cord using the fiber of Example 1 showed good physical properties with a light transmittance of 145 dB/m and a heat resistance temperature of 90°C, but the cord using the fiber of Comparative Example 1 had a light transmittance of 24QdB/m, heat resistant temperature 70'C
There were problems with physical properties.

[Effects of the Invention] The plastic optical fiber and cord of the present invention have a high numerical aperture and excellent light transmission properties, so they are advantageous for use in industrial sensors and signal transmission. Furthermore, because it has a high heat resistance, it can maintain stable characteristics for a long period of time even when used in high-temperature environments.

In addition, since it has good mechanical properties such as flexibility, it is easy to handle and is not restricted by wiring or the like.

Claims (6)

[Claims] (1) The core component is a polymer mainly composed of methyl methacrylate, and the sheath component is a copolymer of vinylidene fluoride and tetrafluoroethylene containing 81 to 85 mol% of vinylidene fluoride. Plastic optical fiber with excellent optical transmission body and heat resistance. (2) A core-sheath composite structure in which the core component is a polymer mainly composed of methyl methacrylate and the sheath component is a copolymer of vinylidene fluoride and tetrafluoroethylene containing 81 to 85 mol% of vinylidene fluoride. An optical transmission body and a plastic optical fiber cord having excellent heat resistance, characterized in that the sheath material is polyethylene, polypropylene, or a copolymer thereof. (3) Claim obtained by a process in which spinning and drawing are directly connected (1)
) listed plastic optical fibers. (4) Stretching ratio 1.5 to 3 times, winding speed V 5/d≦V
The plastic optical fiber according to claim 1, obtained by a process in which spinning and drawing are directly connected under the condition of ≦30/d^2. V: Winding speed m/min d: Fiber diameter mm (5) The plastic optical fiber cord according to claim (2), wherein the plastic optical fiber having a core-sheath composite structure is obtained by a direct spinning/drawing process. (6) A plastic optical fiber with a core-sheath composite structure has a stretching ratio of 1.5 to 3 times and a winding speed of V of 5/d≦V≦30.
The plastic optical fiber cord according to claim 2, which is obtained by a direct spinning/drawing process under the conditions of /d^2. V: Winding speed m/min d: Fiber diameter mm