KR20050058158A - The preform of graded-index plastic optical fiber improved flexibleness and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a graded index (Graded-Index) plastic optical fiber and improved manufacturing method of the flexibility, the manufacturing method of the present invention, in manufacturing a plastic optical fiber base material, an additive having excellent flexibility to all or part of the cladding layer After the addition of the protective layer to form a polymer, it is characterized in that the core portion is formed by polymerizing a monomer mixture solution containing 0.02 to 0.2 mol% of a polymerization initiator and 0.05 to 0.5 mol% of an alkane thiol as a chain transfer agent.

Description

Graded-index plastic optical fiber improved flexibility and manufacturing method etc.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a graded-index plastic optical fiber base material having improved flexibility, and a method of manufacturing the same, wherein the poly (vinylidene fluoride) is applied to all or part of the cladding of the graded-index plastic fiber base material. Poly (vinylidenefluoride-hexafluoropropylene) copolymer} Poly (vinylidenefluoride-tetrafluoroethylene) copolymer} Poly (vinylidenefluoride-hexafluoropropylene) copolymer} Poly (vinylidenefluoride-hexafluoropropylene) copolymer} Poly (vinylidenefluoride-tetra) By adding an additive such as poly (vinylidenefluoride-tetraf {Poly (vinylidenefluoride-tetrafluoroethylene-hexafluoropropylene) triblock copolymer} by adding a fluoroethylene-hexafluoropropylene) triblock copolymer, it has excellent flexibility by producing an optical fiber having an appropriate molecular weight. Plastic optical fiber base material that can withstand external pressure for a long time and its manufacturing method It relates.

Plastic optical fiber has 1) step index type plastic optical fiber (SI-POF) which has high refractive index of core part and low refractive index of cladding part, and 2) structure that the refractive index of core part is lowered with Gaussian distribution from the central axis to the outward direction. It is divided into graded index plastic optical fiber (GI-POF).

Step index type plastic optical fiber is applied to low-speed, low-capacity short-distance transmission, lighting and image guide because light propagates at the discontinuous interface of refractive index, and graded index type plastic optical fiber is based on the principle that light travels at high refractive index. Therefore, since all the incident light modes cross the optical axis, the transmission bandwidth is wide and it is suitable for high-capacity high-speed transmission.

The manufacturing method of Graded-Index type plastic optical fiber includes a manufacturing method using a gel effect using a dopant having a different refractive index, a manufacturing method using a high-speed centrifugal force, or a manufacturing method by adjusting a refractive index by a special extrusion die design. In the manufacturing method using the dopant, the dopant plays a role as a plasticizer inside the optical fiber, and as the content of the dopant is increased, the glass transition temperature is lowered, which lowers heat resistance. There is a disadvantage that it is difficult to manufacture a precise optical fiber. In addition, the manufactured optical fiber has a disadvantage in that tensile property and bending property are inferior and can be easily broken by external impact. This is because communication plastic optical fiber cannot overcome brittleness even by external jacketing.

Therefore, an attempt has been made to coat an additional protective layer, and in the present invention, poly (vinylidenefluoride-tetrafluoroethylene) copolymer, Poly (vinylidenefluoride-hexafluoropropylene) copolymer, or all parts of the cladding of a graded-index plastic optical fiber base material By adding an additive such as poly (vinylidenefluoride-tetrafluoroethylene-hexafluoropropylene) triblock copolymer, an optical fiber having an appropriate molecular weight was prepared to produce a plastic optical fiber having excellent flexibility and withstanding external pressure for a long time.

SUMMARY OF THE INVENTION An object of the present invention is to provide a graded-index plastic optical fiber base material and an additive having flexibility in producing a graded-index plastic optical fiber by drawing it to a part or the whole of the cladding. It is to provide a fiber having excellent flexibility in the drawing process by producing a base material containing and drawing it to reduce the fluctuation of the diameter by reducing the fluctuation in diameter.

In the present invention, the flowability is good, to reduce the diameter variation of the fiber during the drawing process to further suppress the optical loss due to scattering, and also to manufacture the optical fiber base material having the flexibility and to produce the optical fiber having the above properties by drawing this base material Additives are added to some or all of the cladding in the preparation of the optical fiber base material.

More specifically, one or more of additives, such as poly (vinylidenefluoride-tetrafluoroethylene) copolymer, poly (vinylidene fluoride-hexafluoropropylene) copolymer, Poly (vinylidenefluoride-tetrafluoroethylene-hexafluoropropylene) triblock copolymer, in part or all of the cladding region of the base material Mix two or more kinds of methyl-methacylate monomer containing an initiator and a chain transfer agent, and put the mixed solution inside the glass tube and polymerize at 70 ℃ for 2 hours while rotating at a rotational force of about 3000rpm. A protective layer containing an additive by% is formed, and a core part having a refractive index distribution is formed on the protective layer to prepare a graded-index plastic optical fiber base material, which is drawn to have excellent flexibility. Graded-index plastic optical fibers can be produced.

If the volume of the cladding layer containing the protective layer is less than 1% of the total base material volume, the effect of increasing flexibility is insignificant, and if it is more than 60%, it may have a limit in economic efficiency due to light loss and additive price. In addition, the monomer mixed with the additive in the mixed solution used to form the protective layer is BZMA (benzyl-methacrylate), 2,2,2-trifluroethyl-methacrylate, styrene, Tert-butyl methacrylate may be used, and a mixed monomer of the monomers may be used.

In addition, the proportion of the additive in the mixed solution prepared for forming the protective layer is preferably from 10 to 50wt% of the amount of the monomer, the effect is less than this range, if it exceeds this range, mixing with the monomer The state is not uniform and the viscosity is too high, making it difficult to add.

Detailed manufacturing method is as follows. First, a suitable amount of one or two or more of the above-mentioned additives is mixed with methyl-methacylate, and stirred to prepare a solution having a certain flowability, and AIBN 0.01 to 0.2 mol% (preferably 0.06mol% is appropriate), 1-buthanthiol 0.05 ~ 0.5mol% (preferably 0.2mol% is suitable) as a chain transfer agent, and then it is put in a glass tube 50mm in diameter and 960mm in length and rotates at 1,000 ~ It rotates at 10,000 rpm and performs superposition | polymerization at 60-150 degreeC of polymerization temperatures.

In this case, BPO (Benzoyl Peroxide) and Dimethyl 2,2-azobis (2-methylpropionate) may be used as an initiator, and 1-dodecane-thiol may be used as a chain transfer agent. After forming the additional cladding layer on the inner side of the cylindrical protective layer thus prepared to form a core portion, or immediately adjusting the content of the initiator and the chain transfer agent in a conventional manner, using a gel effect using a conventional dopant, high-speed centrifugal force The base material can be manufactured by forming a core part using conventional methods, such as the method using the method or the method by a special extrusion die | dye.

The prepared base material can be drawn at an appropriate temperature to produce graded index plastic fiber with very high flexibility. In the case of the optical fiber manufactured by the present invention, the additive is partially or entirely added to the cladding of the base material. By adding to the result, the core to which an effective optical signal is transmitted has no increase in optical loss due to the additive, while the flexibility is significantly improved.

An embodiment of the present invention is as follows.

<Example 1>

330 g of a mixed solution of methyl methacrylate and poly (vinylidenefluoride-tetrafluoroethylene) copolymer having a weight ratio of 7: 3 was prepared, and AIBN 0.06 mol% and 1-butanethiol 0.2mol% were added as a chain transfer agent. The prepared mixed solution was introduced into a glass tube having a diameter of 50 mm and a length of 960 mm, and polymerized at 70 ° C. for 2 hours while rotating at about 3000 rpm to prepare a PMMA cladding layer (protective layer) containing an additive. The volume of the protective layer thus prepared is about 13% of the total base material volume. After several additional methyl methacrylate was added to the protective layer to form an additional cladding layer up to about 56% of the total base material volume, the core part having a refractive index distribution of 0.06 mol% AIBN (N, N-azobis-isobutyronitrile) was used as an initiator 0.2 Using mol-% 1-butane-thiol as a chain transfer agent was prepared by adjusting the refractive index distribution in a conventional method by high-speed centrifugal force.

After the polymerization of the core is completed, the preform is separated from the glass tube and put into a vacuum oven at a temperature of 70 to 120 ° C. to remove residual monomer for about 24 hours. Heated to the preform thus prepared to draw it to produce a graded-index plastic optical fiber (Graded-Index). The flexibility was measured by measuring the minimum bending diameter and the maximum number of breaks of the optical fiber thus manufactured, and the results are shown in Table 1 below.

<Example 2>

Methyl methacrylate and poly (vinylidenefluoride-hexafluoropropylene) copolymer 330g of a mixed solution having a weight ratio of 7: 3 was prepared, and optical fibers were prepared in the same manner as in Example 1, and the minimum bending diameter and the maximum number of fractures were measured.

<Example 3>

Methylmethacrylate and Poly (vinylidenefluoride-tetrafluoroethylene-hexafluoropropylene) triblock copolymer 330g of a mixed solution having a weight ratio of 7: 3 was prepared to prepare an optical fiber in the same manner as in Example 1, the minimum bending diameter and the maximum number of breaks were measured.

<Example 4>

Methyl methacrylate and poly (vinylidenefluoride-tetrafluoroethylene) copolymer 330g of a mixed solution having a weight ratio of 8: 2 was prepared to prepare an optical fiber in the same manner as in Example 1, and the minimum bending diameter and the maximum number of fractures were measured.

Example 5

Methyl methacrylate and Poly (vinylidenefluoride-tetrafluoroethylene) copolymer 330g of a mixed solution having a weight ratio of 9: 1 was prepared to prepare an optical fiber in the same manner as in Example 1, and the minimum bending diameter and the maximum number of fractures were measured.

<Example 6>

330 g of a mixed solution of methyl methacrylate and poly (vinylidenefluoride-tetrafluoroethylene) copolymer having a weight ratio of 7: 3 was prepared, and AIBN 0.06 mol% and 1-butanethiol 0.2mol% were added as a chain transfer agent. The prepared mixed solution was placed in a glass tube having a diameter of 50 mm and a length of 960 mm, and polymerized at 70 ° C. for 2 hours while rotating at about 3000 rpm to prepare a PMMA cladding layer containing an additive. The volume occupied by the protective layer thus prepared is about 13% of the total base material volume. After the temperature was raised to 90 ° C., the mixed solution prepared previously was added to the protective layer several times to form an additional protective layer up to about 56% of the total base material volume, and then the core part having a refractive index distribution thereon was 0.06 mol% of AIBN. (N, N-azobis-isobutyronitrile) using 0.2 mol% of 1-butane-thiol as a chain transfer agent as an initiator was prepared by adjusting the refractive index distribution in a conventional method by high-speed centrifugal force. After the polymerization of the core is completed, the optical fiber base material is separated from the glass tube and put into a vacuum oven at a temperature of 70 to 120 ° C. to remove residual monomer for about 24 hours. Heated to the base material thus prepared is drawn to produce a graded-index plastic optical fiber. The flexibility was measured by measuring the minimum bending diameter and the maximum number of breaks of the optical fiber thus manufactured.

Comparative Example 1

The optical fiber was manufactured in the same manner as in Example 1 without the addition of additives, and the minimum bending diameter and the maximum number of fractures were measured.

The flexibility of the example was tested by two methods, the minimum bending diameter (Ø) and the maximum number of breaks (Number of flexings to break). The minimum bending diameter was measured by the diameter of the rod when it was wound 100 times or more without breaking POF with the same force on various diameter rods, and the maximum breaking frequency was the reciprocating frequency when breaking by reciprocating the POF by ± 90 °. Measured.

As shown in Table 1, the improvement of flexibility was remarkable due to the addition of the additive, and when the additive was not added or the ratio of the additive in the mixed solution was 10wt% or less, the maximum breakage frequency was 10,000, indicating a decrease in flexibility. It was.

TABLE 1

division additive Additive Ratio (wt%) Protective layer volume fraction Bending diameter (mm) Maximum number of breaks (times) Example 1 Poly (VDF-TFE) 30 0.13 One More than 20,000 Example 2 Poly (VDF-HFP) 30 0.13 One More than 20,000 Example 3 Poly (VDF-TFE-HFP) 30 0.13 One More than 20,000 Example 4 Poly (VDF-TFE) 20 0.13 2 More than 20,000 Example 5 Poly (VDF-TFE) 10 0.13 3 More than 15,000 Example 6 Poly (VDF-TFE) 30 0.56 One More than 20,000 Comparative Example 1 X 0 0 10 5,000

 -Additive ratio: Weight ratio (%) of additives in mixed solution used in the manufacture of protective layer

 -Protective layer volume fraction: Volume fraction of protective layer (cladding layer containing additives) in the base material (protective layer volume) / (total base material volume)

The present invention is to improve the flexibility of the optical fiber by forming a protective layer containing a flexible additive in part or all of the cladding when manufacturing a graded-index plastic optical fiber, the external pressure compared to the conventional plastic optical fiber It provides the base material of the plastic optical fiber which is strong in the impact by the excellent transmission rate and the plastic optical fiber using the same

Claims (7)

In manufacturing the plastic optical fiber base material, after adding a highly flexible additive to all or part of the cladding layer to form a protective layer, the polymerization initiator 0.02 ~ 0.2mol%, the alkane thiol 0.05 ~ 0.5mol% as a chain transfer agent therein A method for producing a graded index type plastic optical fiber base material, characterized in that the polymer portion is polymerized to form a core portion. The method of claim 1, wherein the additive is poly (vinylidene fluoride-tetrafluoroethylene) copolymer, poly (vinylidene fluoride-hexafluoropropylene) copolymer, poly (vinylidene fluoride-tetrafluoroethylene-hexa Method for producing a graded index type plastic optical fiber base material, characterized in that at least one selected from fluoropropylene) triblock copolymer. The method of claim 1, wherein the monomer used in the preparation of the protective layer or core portion is methyl methacrylate, benzyl methacrylate, 2,2,2-trifluoroethyl-methacrylate, styrene, tert-butyl methacrylate. Wherein the polymerization initiator is one of N, N-azobis-isobutyronitrile, benzoyl peroxide or dimethyl2,2-azobis (2-methylpropionate). Method for manufacturing an optical fiber base material. The method of claim 1, wherein the chain transfer agent is one of 1-butane-thiol and 1-dodecane-thiol. A graded index type plastic optical fiber base material produced by the method of any one of claims 1 to 4. 6. The graded index according to claim 5, wherein the volume ratio of the protective layer in the entire base material is 1 to 60 vol%, and the ratio of the additive to the monomer in the mixed solution used for forming the protective layer is 10 to 50 wt%. Type plastic optical fiber base material. A graded index type plastic optical fiber manufactured by drawing by a conventional method using the plastic optical fiber base material according to any one of claims 5 and 6.