JPS6152616A - Glass fiber for optical transmission - Google Patents

Abstract

PURPOSE:To obtain an optical fiber which is free from an increase in transmission loss over a long period of time by coating an Si resin compsn. consisting of diorganopolysiloxane, organohydrogene polysiloxane and platinum on said fiber thereby decreasing the amt. of the H2 to be generated. CONSTITUTION:The Si resin compsn. which consists of (a) diorganopolysiloxane, (b) organohydrogene polysiloxane having at least three Si atom-bonded H2 atoms in one molecule and (c) platinum or plainum compd., has 0.7-1.5 molar ratio of the Si atom-bonded vinyl group in the component (b) and in which the component (c) is 20-200ppm of the total amt. of both components (a) and (b) is coated on the fiber. The initial transmission loss characteritic and strength characteristic are thus provided to the fiber; in addition, the amt. of the H2 to be generated from the Si resin is decreased even at ordinary and high temp. and the fiber which is free from an increase in the transmission loss on a long period of time and has excellent long-term stability is obtd.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a glass fiber for optical transmission (hereinafter referred to as the original fiber).
The present invention relates to an optical fiber provided with a thermosetting coating that improves the amount of generation and in particular guarantees the long-term stability of the optical fiber. The present invention can be very advantageously applied in fields using optical communication fibers and other optical fibers.

(Prior Art) As an optical communication fiber, a structure in which the surface of a quartz-based glass fiber consisting of a core and a cladding is coated with a thermosetting silicone resin is well known and is widely used in practical use. However, some cable structures have been found to have the disadvantage of increasing infrared transmission loss over time, which occurs due to H2 reacting with defects in the glass [ E Daitron, /Lett
, Volume 19 (1984) pp. 762-764], the main source of H2 generation is thermosetting silicone, ["Co
nference on optical fiber
(iommunication, Po5t Dea
dline Papers' Wr5-1~WI3-
4, (1984)], etc. have been clarified. Therefore, in order to guarantee the long-term stability of the optical communication system, it is essential to use heated materials that generate less H2.

The thermosetting silicone resin used to coat the optical fiber here consists of general K, ■base oil, ■crosslinking agent (
Trifunctional or higher functional silane 1. or siloxane) and ■curing catalyst.

The pace oil (2) is generally a diorganopolysiloxane having functionality only at the terminal and is represented by the general formula (1), where R is an alkyl group such as methyl, ethyl, globil, or an aryl group such as phenyl or tolyl. , cyclohexyl, cyclohegetyl, and other cycloalkyl groups; and those in which the hydrogen atom bonded to the carbon atom of the above-mentioned hydrocarbon group is partially substituted with a hydrogen atom, a cyano group, or the like.

Among these, those in which all R's are methyl groups, or those consisting of methyl groups and phenyl groups, are often put to practical use.

The crosslinking agent (2) is a trifunctional or higher-functional silane or siloxane that forms a crosslinking bond by reaction with the vinyl group of the general formula (2) of the pace oil and cures the composition. It has three or more hydrogen atoms directly bonded to a silicon atom.

The catalyst (2) is for promoting the formation of cross-linking bonds between the above-mentioned pace oil and cross-linking agent, and is powdered platinum, which is adsorbed on a holding carrier.

Chloroplatinic acid, potassium chloroplatinate, sodium chloroplatinate,
Examples include alcohol-modified chloroplatinic acid, a complex of chloroplatinic acid and an olefin, and the like.

The pace oil and the crosslinking agent undergo an addition reaction as shown in the following formula (2), for example, in the presence of a platinum catalyst.

pt catalyst Mi5i (iH= CH2+ H81 Mi-→ MiSECR
2CH251mi... (2) At this time, the molar ratio of SiHa to vinyl group is usually 0.7 to 3.0. The reason for this is that if the amount of SiH groups is small, sufficient crosslinking density cannot be obtained and curing is insufficient, while if the amount of SiH groups is too large, the crosslinking agent component (2), which does not participate in the crosslinking reaction, remains in the resin. This is because the physical properties of the cured composition are deteriorated.

The platinum catalyst in (1) is usually contained in an amount of 5 to 10 ppm in the total weight of (2) to (2).

Conventional silicone resins as mentioned above are extremely excellent as coating materials for optical fibers in terms of processability such as viscosity, pot life, curing speed, etc., as well as optical fiber properties such as optical fiber strength and initial transmission loss. love. However, as mentioned above, with the current resin composition, H
It was found that the optical fiber coating material had a serious defect in that 2 was generated and the transmission loss deteriorated.

(Disadvantages to be Solved by the Invention) The present invention solves the above-mentioned drawbacks, that is, reduces the amount of H2 generated by thermosetting silicone, which has excellent characteristics in terms of initial transmission loss, strength, etc. The objective is to provide an optical fiber that does not have increased transmission loss over a long period of time.

(Means for Solving the Problems) As a result of various studies on silicone resin compositions that reduce the amount of H2 generated and do not increase transmission loss over a long period of time, the inventors found that the processability of the resin, the coated optical fiber The present invention realizes an optical fiber that satisfies the conventional level of initial characteristics, generates zero H2, and does not cause an increase in transmission loss in accelerated aging tests. A diorganopolysiloxane represented by the general formula (wherein R is a substituted or unsubstituted monovalent hydrocarbon group having no aliphatic unsaturated bond, and n is a positive integer), (Rof 1 An organohydrodiene polysiloxane having at least 3 silicon-bonded hydrogen atoms in the molecule, (/-1 platinum or platinum compound), consisting of the above three components, a silicon atom bond in the above component (b) The molar ratio of the hydrogen atom to the silicon atom-bonded vinyl group in component (a) is in the range of 0.7 to 1.5, and the Oi component is in the range of (A), (B) both components. Total amount of 20
The present invention provides a glass fiber for optical transmission coated with a silicone resin composition having a silicone resin composition of 200 ppm.

(a) The diorganosiloxane represented by the general formula of the component (wherein R is a substituted or unsubstituted monovalent hydrocarbon group having no aliphatic unsaturated bond, and n is a positive integer) , for example, etc. are used.

Examples of the organohydrodiene polysiloxane having at least three silicon-bonded hydrogen atoms in one molecule of component (b) include the following.

As the platinum or platinum compound as the ρ9 component, for example, a 2% by weight solution of chloroplatinic acid in 2-ethylbequitenol and a 2% by weight solution of chloroplatinic acid in inpropyl alcohol can be used.

The feature of the present invention is that it can be used as a coating material for optical fiber (l si
The molar ratio of H group to vinyl group is 0.7 to 1.5, and (
The reason is that a silicone resin is used in which the amount of platinum catalyst is 20 to 200 ppm based on the total weight of the silicone resin.

However, the amount of platinum catalyst may be 200 ppm or more, but the composition of the present invention is necessary and sufficient for the effect of reducing H2 generation17, and when the amount of platinum catalyst is 200 ppm or more, the resin tends to deteriorate quickly. be.

(Function) The silicone resin-coated optical fiber of the present invention has the same properties as conventional silicone JfJ! at room temperature and high temperature. H2 generated in the silicone resin, as seen in oil-coated optical fibers.
There is no increase in transmission loss due to The reason for this is estimated by the present inventors as follows.

That is, firstly, the molar ratio of SiH groups to vinyl groups is 0.7.
- 1.5, so the following (2i type) does not participate in the reaction and remains in the silicone resin after curing is small. Secondly, there is a small amount of 5i remaining (5i) (the group is the following (3) ) In the presence of a large amount of H2t-1 platinum catalyst generated in the reaction of the formula,
This is because it can be consumed as shown in the following equation (4) by reaction with 0□.

The silicone resin composition of the present invention is (a).

It is not limited to the three components (b) and ←, and other additives may be added to increase τ, and the effectiveness of the present invention will not change even in that case.

The experimental data from which the findings that form the basis of the present invention were obtained will be explained below. The silicone resin composition used here is a 2x volume % solution of f-1 chloroplatinic acid in 2-ethylhexanol. 150% silicone resin with these three ingredients
It was cured by heating at C for 15 minutes and used for testing. The cured silicone product was heated at 2000 °C for 1 hour in an air atmosphere, and the generated H2 gas was analyzed by gas chromatography using Ar carrier gas.

The results of the above experiment are expressed as the molar ratio of SiH groups and vinyl groups, the amount of platinum (ppm), and the amount of H2 generated [at / (i resin)]
Figure 1 shows the correlation diagram. Regarding the amount of platinum,
It hails 5ppm as marked by "X", 10ppm as marked by Δ, 15ppm as marked by "15ppm", 20ppm as marked by "○", 1100ppm as marked by @, and 200ppm as marked by "+".

As is clear from FIG.
It can be seen that silicone resin with a composition of ppm has substantially zero H2 generation.

(Effects of the Invention) The silicone resin-coated optical transmission fiber of the present invention not only has the excellent initial transmission loss characteristics and strength characteristics of the conventional silicone resin-coated optical fiber, but also has excellent initial transmission loss characteristics and strength characteristics that are caused by the silicone resin both at room temperature and high temperature. It is an optical fiber that reduces the amount of H2 generated and has excellent long-term stability with no increase in transmission loss over a long period of time.

(Example) The effectiveness of the present invention will be illustrated below with reference to Examples.

Example 1 A silica-based optical fiber preform with a relative refractive index difference of 1% and containing Gs as a dopant was drawn in a carbon resistance furnace type drawing furnace to obtain a fiber with an outer diameter of 125 μm. Thereafter, a silicone resin with a high refractive index was coated to a thickness of 60 μm and baked in an infrared oven, and then a silicone resin with a low refractive index was coated to have an outer diameter of 4 D OArn and baked in an infrared oven. At this time, the temperature of the drawing furnace was 2150C, the ffa drawing speed was 60 m/min, and the temperature of the infrared furnace was 450C.

What is the composition of the silicone resin used in this case?

(c) A 2% by weight solution of chloroplatinic acid in Improvil alcohol), ■ The molar ratio of SiH groups to vinyl groups is 1.0 ■ The concentration of platinum is 30 ppm (I) and ρ Mixed with arrogance.

The optical fiber coated with the above silicone resin was extruded with a knife 12 to an outer diameter of 0.91ffl+lφ, and
An accelerated test of H2 generation and loss increase was conducted at p.

The amount of H2 generated was determined by analyzing the amount of H2 gas generated in one hour at 20 DC using a gas chromatogram using Ar carrier gas. The amount of H2 generated is 5XIQ-'ml per 91 m.
was below the lower limit of quantification.

In the accelerated loss increase test, the loss wavelength characteristics were changed to 6 at 200C.
Measured after hours, 0.05 at 1.39μm OH peak
It was confirmed that there was no problem with the increase in c[/&.

Example 2 Go was used as a dopant, the relative refractive index difference was 1%, and P was 1.
A silica-based optical fiber containing 5% was drawn under the same conditions as in Example 1. The composition of the silicone resin used at this time differed from Example 1 only in the amount of platinum, which was 100 ppm.

This wire was made into a nylon core wire in the same manner as in Example 1 and was subjected to a test. H2 generating element after 1 hour at 200C is 1m of core wire.
The loss increase property is below the lower limit of quantification of 4 x 10-7 per unit, and the increase in loss at 1.39 μm peak after 6 hours at 200C is 0.
It was confirmed that the level was 1 dB/&s, which is acceptable.

Comparative Example A silica-based optical fiber with a relative refractive index difference of 1% was drawn under the same conditions as in Example 1 using Ge as a dopant. The silicone resin composition used at this time was different from Example 1 in the molar ratio of SiH groups to vinyl groups and the amount of platinum. In high refractive index silicone resin, the molar ratio of SiH groups to vinyl groups is 3.
In a silicone resin with a platinum concentration of 5 ppm and a low refractive index, the molar ratio of SiH groups to vinyl groups is 2.5, and the platinum content is 8.
It is ppm. This wire was made into a nylon core wire in the same manner as in Example 1 and was subjected to a test. The amount of H2 generated after 1 hour at 200C is 0.027 d per 1 meter of core wire, and the increase in loss at 1.39 μm after 20006 hours is 5.
．． 26B/! [It was +s.

[Brief explanation of drawings]

FIG. 1 is a graph showing the relationship between the amount of H2 generated when the molar ratio of SiH groups to vinyl groups of the silicone resin used for coating and the amount of platinum are changed.

Claims (1)

[Claims] 1. Glass fiber for optical transmission has (a) general formula ▲ mathematical formula, chemical formula, table, etc. (b) an organohydrodiene polysiloxane having at least three silicon-bonded hydrogen atoms in one molecule; c) Platinum or a platinum compound, consisting of the above three components, wherein the molar ratio of the silicon-bonded hydrogen atoms in the above-mentioned (b) component to the silicon-bonded vinyl groups in the above-mentioned (a) component is 0.7 to 1. .5, and the component (c) above is 2 of the total amount of both components (a) and (b) above.
A glass fiber for optical transmission coated with a silicone resin composition having a concentration of 0 to 200 ppm.