JPH07191242A - Primary coated film layer of optical fiber - Google Patents

Abstract

PURPOSE:To provide a primary coated film layer of optical fiber, which is composed of a polybutylene terephthalate resin composition having excellent mechanical strength under a high temp. and sufficient elastic modulus. CONSTITUTION:The primary coated film layer of optical fiber is formed from the polybutylene terephthalate resin composition containing 0.05-3 pts.wt. cyclic organic phosphate metallic salt expressed by the formula per 100 pts.wt. polybutylene terephthalate having relative viscosity of 2.2-3.3. In the formula, each of R1 and R2 represents hydrogen atom, alkyl group, arylalkyl group, aryl group or alkylaryl group, X represents direct bond hand, alkylidene group or sulfur atom, M represents metallic atom, (n) represents the valency of metal. The polybutylene terephthalate is one kind of a crystalline thermoplastic polyester and is made worse in moldability and is not suitable for the primary coated film layer if the relative viscosity is out of the range. And if the quantity of the cyclic organic phosphate to be blended is <0.05, the effect is not shown and even if the quantity to be blended is over 3 pts.wt., the effect is not changed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber primary coating layer, and more particularly to an optical fiber primary coating layer using a polybutylene terephthalate resin composition capable of withstanding processing at high temperatures.

[0002]

2. Description of the Related Art Optical fiber strands for optical communication are made of a brittle material such as quartz or optical glass, and are covered with plastic as a primary coating to reinforce them. As the primary coating, polybutylene terephthalate is mainly used because it has excellent mechanical properties such as low water absorption, abrasion resistance and dimensional stability.

Further, the optical fiber cable is formed by bundling a plurality of optical fiber element wires (optical fiber core wires) coated with a primary coating, in a single core or in a large number, and applying a secondary coating thereto. The secondary coating is generally made of a thermoplastic resin such as nylon, polyethylene or polypropylene. That is, for example, as shown in FIG. 1, an optical fiber cable 1 has a structure in which a large number of optical fiber core wires 3 having a primary coating 2 are bundled and housed in a cable composed of a secondary coating layer 4. . A space between the plurality of optical fiber cores 3 is filled with, for example, a jelly-like substance 5 as a cushioning material.

Generally, the manufacture of optical fiber cables
This is carried out by a process of molding a thermoplastic resin as a secondary coating into a pipe shape as a cable by extrusion molding, and at the same time inserting a large number of optical fiber core wires coated with a primary coating into the inside thereof. At this time, the one using the cushioning material is also filled inside the cable at the same time.

When the jelly-like substance is filled, the jelly-like substance is usually heated and filled in order to reduce the viscosity of the jelly-like substance and facilitate the filling operation. Therefore, the simultaneously inserted optical fiber cores are heated to a considerable temperature. Even when the jelly-like substance is not filled, the heat of the secondary coating resin to be extruded is transferred, and it must be heated to a considerable temperature.

Further, the above-mentioned optical fiber cable is molded at high speed, and the core wire subjected to the insertion operation is subjected to stress such as considerable tensile stress and torsion stress, and the primary coating layer made of polybutylene terephthalate is also applied at the same time. Receive stress.

[0007] However, polybutylene terephthalate has a relatively low glass transition temperature,
When stress is applied under heating, the mechanical properties deteriorate. This decrease in mechanical properties results in, for example, a decrease in elastic modulus,
After the cable is manufactured, it may cause the deformation of the optical fiber core, and in an extreme case, the cable itself may be bent. The deformed optical fiber core also lowers the optical transmission efficiency in the extreme case, and may cause a trouble in connection work of the optical fiber core during cable connection.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical fiber primary coating layer in which the above problems have been solved. More specifically, it has excellent mechanical properties at high temperatures,
It is to provide a primary coating layer of an optical fiber made of a polybutylene terephthalate resin composition having a sufficient elastic modulus.

[0009]

The above object of the present invention is solved by adding a cyclic organic phosphate metal salt to polybutylene terephthalate.

That is, the present invention has a relative viscosity of 2.2 to
Polybutylene terephthalate 100 in the range of 3.3
Cyclic organic phosphate metal salt represented by the following general formula (I) with respect to parts by weight.

[0011]

[Chemical 2]

(In the formula, R ₁ and R ₂ each represent a hydrogen atom, an alkyl group, an arylalkyl group, an aryl group or an alkylaryl group, X represents a direct bond, an alkylidene group, or a sulfur atom. Represents a metal atom, and n represents the valence of the metal.) An optical fiber primary coating layer made of a polybutylene terephthalate resin composition containing 0.05 to 3 parts by weight, and an optical fiber core wire coated with the primary coating layer. It is provided.

The present invention will be described in more detail below.

The polybutylene terephthalate used in the present invention is a kind of crystalline thermoplastic polyester. This polybutylene terephthalate is generally melt-polymerized by a polycondensation reaction of terephthalic acid or its alkyl ester with 1,4-butanediol. 40 mol% each of acid component or alcohol component
The following amounts can be replaced by acids other than terephthalic acid and alcohols other than 1,4-butanediol. As these copolymerization components, for example, as an acid component, aliphatic dicarboxylic acids such as adipic acid and sebacic acid; alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid;
Aromatic dicarboxylic acids such as isophthalic acid; Alcohol components such as ethylene glycol, 1,2-butanediol, 1,3-butanediol, 1,6-hexanediol and other aliphatic glycols; 1,4-cyclohexanedimethanol, etc. Alicyclic glycols; aromatic glycols such as 4,4′-hydroxyethyl-oxyphenylpropane, and the like.

The polybutylene terephthalate used in the present invention is generally, for example, dimethyl terephthalate and 1,4-butanediol in an excess molar amount relative to it, in the presence of a catalyst, after transesterification at 130 to 260 ° C. and then under reduced pressure. It is possible to produce one having an arbitrary molecular weight by condensation.

The polybutylene terephthalate used in the present invention has a relative viscosity (weight ratio of phenol to ethane tetrachloride of 6: 4).
In a mixed solvent of 30 ° C at a concentration of 1 g / dl, JIS
K-2283) has a range of 2.2 to 3.3. When it is out of this range, the moldability is deteriorated, so that it is not suitable as a primary coating layer for an optical fiber.

The cyclic organic phosphate metal salt of the general formula (I) used in the present invention will be described in detail. Examples of the alkylidene group represented by X include methylidene, ethylidene, isopropylidene, butylidene, hexylidene,
Groups such as octylidene, nonylidene, cyclopentylidene, cyclohexylidene, cyclooctylidene and the like can be mentioned.

Examples of the alkyl group represented by R ₁ and R ₂ include methyl, ethyl, isopropyl, n-butyl, isobutyl, sec-butyl, sec-butyl, n-amyl and sec-
Examples include groups such as amyl, hexyl, heptyl, n-octyl, 2-ethylhexyl, tertiary octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, cyclohexyl, cyclopentyl, and arylalkyl. Examples of the group include groups such as benzyl, phenylethyl and phenylpropyl, examples of the aryl group include groups such as phenyl and naphthyl, and examples of the alkylaryl group include groups such as tolyl, xylyl and isopropylphenyl.

The metal atom represented by M is L
i, Na, K, Be, Mg, Ca, Sr, Ba, Zn,
Cd, Al, Ge, Sn, Pb, Ti, Zr, Sb, C
r, Bi, Mo, Mn, Fe, Co, Ni and the like, particularly, Group Ia metals such as Li, Na and K and Mg,
Group IIa metals such as Ca, Sr, Ba are preferred.

Specific examples of the compound represented by the above general formula used in the present invention are shown below.

[0021]

[Chemical 3]

[0022]

[Chemical 4]

[0023]

[Chemical 5]

[0024]

[Chemical 6]

[0025]

[Chemical 7]

[0026]

[Chemical 8]

[0027]

[Chemical 9]

[0028]

[Chemical 10]

The amount of the cyclic organic phosphate to be blended is 0. 0 per 100 parts by weight of the polybutylene terephthalate.
05 to 3 parts by weight. If the amount is less than 0.05, the effect of the present invention cannot be obtained. Further, even if the amount exceeds 3 parts by weight, the effect does not change, and it becomes economically disadvantageous to add a large amount.

The composition of the present invention can not only form the coating layer without any problem, but also maintain the elasticity required during the production of the optical fiber cable and form the optical fiber cable without any trouble.

In addition to the above components, the composition of the present invention also comprises
The following fillers may be added within a range that does not impair the effects of the present invention. Such fillers include fibrous fillers such as pigments, glass fibers, carbon fibers, potassium titanate, asbestos, silicon carbide, ceramic fibers, metal fibers and silicon nitride; barium sulfate, calcium sulfate, bentonite, sericite, mica. , Mica, talc, ferrite, calcium silicate, calcium carbonate, magnesium carbonate, dolomite, zinc oxide, titanium oxide, magnesium oxide, iron oxide, molybdenum trioxide, antimony trioxide, graphite, gypsum, glass powder,
Examples thereof include inorganic fillers such as glass balloons, quartz, and quartz glass, and organic fillers such as aramid fibers.
This can be added in an amount of 1 to 95% by weight based on the entire polybutylene terephthalate resin composition of the present invention. In addition, a small amount of release agent, coupling agent, colorant,
A flame retardant auxiliary agent such as a lubricant, a heat resistance stabilizer, a weather resistance stabilizer, a foaming agent, a flame retardant, or antimony trioxide may be appropriately added.

In carrying out the present invention, as a method for blending the compound represented by the general formula (I) with polybutylene terephthalate, a conventionally known method can be applied. Before the polymerization of polybutylene terephthalate, during the polymerization and after the polymerization, Can be added at any stage. For the compounding after the polymerization, a conventionally known method can be applied, and for example, kneading and mixing can be performed by a dry mixing method, a melt mixing combination method, a multistage melt mixing method, a simple melt mixing method, or the like. If necessary, a single-screw extruder, a twin-screw kneader, a cokneader, a Banbury mixer, a Henschel mixer and the like can be used for blending.

As a method for coating the polybutylene terephthalate resin composition of the present invention on the optical fiber core wire as a primary coating, a conventionally known method can be applied. For example, in the extrusion coating apparatus as shown in FIG. Is melt-extruded from an extruder (not shown), supplied to a coating device 7 to coat the optical fiber strand 3 with a coating nozzle 8 and cooled and solidified through a cooling tank (not shown) to form an optical fiber core 9. and so on.

The primary coating layer obtained by the above method or the like has remarkably improved mechanical properties at high temperatures and is less likely to be thermally deformed. Further, since it has a sufficient elastic modulus, the primary coating layer made of polybutylene terephthalate does not deform or bend due to heat or tensile tension even in the secondary coating forming step, so that a decrease in light transmission speed may occur. There is no.

The present invention will be specifically described below with reference to examples.

(Example 1) The relative viscosity of a mixed solution of tetrachloroethane and phenol of 40/60 was 2.8 (JIS K-2283) under the conditions of 30 ° C and a concentration of 1 g / dl.
(Compliant) polybutylene terephthalate, a cyclic organic phosphate metal salt (trade name MARKNA-11,
Asahi Denka Kogyo Co., Ltd. made polybutylene terephthalate 10
0.2 parts by weight per 0 parts by weight was added and mixed with a Henschel mixer, and kneaded with a 50 mmφ single screw extruder to obtain a pelletized composition. A sheet having a thickness of 0.5 mm was formed from this composition by compression molding, and a test piece was prepared from the sheet, and a tensile test was performed in an atmosphere of 60 ° C. The results are shown in Table 1.

[0037]

[Table 1]

In the optical fiber core wire which was primarily coated with the above composition using the extrusion coating apparatus of FIG. 2, the primary coating layer was not deformed in the secondary coating forming step.

[0039]

[Effect] The polybutylene terephthalate used in the optical fiber primary coating layer of the present invention has significantly improved mechanical properties at high temperatures as compared with conventional polybutylene terephthalate, and has a sufficient elastic modulus to be used as the optical fiber primary coating layer. When used, the coating layer is less likely to be deformed due to heat during cable production, and the optical transmission efficiency is not lowered due to bending of the fiber.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an optical fiber of a type in which a gel is included between a primary coating layer and a secondary coating layer.

FIG. 2 is a schematic view of a cable processing coating device.

[Explanation of symbols]

1 optical fiber cable, 2 primary coating layer, 3
Optical fiber core wire, 4 secondary coating layer, 5 jelly-like substance, 6 PBT resin composition, 7 coating device,
8 coating nozzle, 9 optical fiber strand

Claims (1)

[Claims] 1. A cyclic organic phosphate metal salt represented by the following general formula (I) in an amount of 0.05 to 3 parts by weight with respect to 100 parts by weight of polybutylene terephthalate having a relative viscosity of 2.2 to 3.3. An optical fiber primary coating layer made of a polybutylene terephthalate resin composition containing a. [Chemical 1] (In the formula, R ₁ and R ₂ each represent a hydrogen atom, an alkyl group, an arylalkyl group, an aryl group or an alkylaryl group, X represents a direct bond, an alkylidene group, or a sulfur atom. M represents a metal atom. , And n represents the valence of the metal.)