JPH0445187A - Waterproofing admixture - Google Patents

Abstract

PURPOSE:To obtain a waterproofing admixture for packing into optical fiber cable evolving a small amount of hydrogen and having no increase in transmission loss of optical fiber for a long period of time, containing a base oil comprising a specific hydrocarbon oil and a thickening agent. CONSTITUTION:The objective admixture containing (A) a base oil comprising a hydrocarbon oil having <=1.2 (preferably <=0.6) iodine value and preferably 200-10,000 (especially <=2,000) number-average molecular weight, preferably obtained by hydrogenating a polymer of an alpha-olefin and (B) 1-80wt.% thickening agent comprising especially preferably fumed silica.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a waterproof mixture for filling optical fiber cables that generates a small amount of hydrogen and does not increase the transmission loss of optical fibers over a long period of time.

(Prior art) Conventionally, as a waterproofing mixture for filling optical fiber cables,
Hydrocarbon oils that are polymers of α-olefins and their hydrogenated products, such as 22 Royal Company (USA) (1) S Y
Waterproofing mixtures using NTONPAO or the like as a base oil are known (Japanese Unexamined Patent Publication Nos. 61-84614, 61-126706, etc.).

(Problems to be Solved by the Invention) However, these waterproof mixtures have a problem in that they generate a large amount of hydrogen when heated or left for a long period of time, increasing the transmission loss of the optical fiber.

(Means for Solving the Problems) As a result of intensive research to solve the above problems, the present inventors have found that by using a hydrocarbon oil with a particularly low iodine value as a base oil, the increase in transmission loss due to hydrogen generation can be reduced. We have discovered that this can be prevented for a long period of time, and have completed the present invention.

That is, the present invention provides an optical fiber cable filling waterproof mixture containing a base oil and a thickener, which is characterized in that a hydrocarbon oil having an iodine value of 1.2 or less is used as the base oil. The present invention provides a waterproof admixture for use in water.

The hydrocarbon oil used as the base oil in the present invention is not particularly limited as long as it has an iodine value of 1.2 or less, but especially highly branched oils in which olefins are polymerized by ionic or radical reactions. It is preferable to use a chain-like synthetic hydrocarbon oil that is hydrogenated in the presence of a hydrogenation catalyst.

The above-mentioned olefin may be any hydrocarbon having a polymerizable unsaturated bond in its molecule, but it usually has 3 to 25 carbon atoms, such as propylene, 1-butene, 2-butene, etc.
Butene, isobutyne, 4-methyl-1-pentene, 1-
Pentene, 1-hexene, 1-octene, l-decene,
Examples include 1-dodecene, -octadecene, and l-eicosene.

Among them, hydrocarbon oils synthesized from α-olefins such as propylene, 1-butene, isobutyne, 1-octene, 1-decene, and 1-dodecene have low viscosity at low temperatures and are suitable for waterproofing mixtures. It is preferred because it increases the consistency at low temperatures.

The above olefin polymerization method includes, for example, introducing an olefin into a solvent such as a halogenated carbon or hydrocarbon containing a polymerization catalyst at a predetermined temperature and polymerizing it, followed by removing the remaining catalyst by removing the solvent, removing the dimer, and washing with an alkali. There is a method of synthesis through the following steps.

As the polymerization catalyst, (1) a Friedel-Krach type catalyst, a hydrogen acid, a halogen, an alkali metal, an organic alkali metal compound, an organic alkaline earth metal compound, a Grignard reagent, etc. are used alone, and (2) a Ziegler reagent is used alone. Composite catalysts such as type catalysts, DuPont catalysts, standard catalysts, and Phillips catalysts may be used. Among these, a composite catalyst in which a complex is formed with a Lewis acid such as boron trifluoride or aluminum chloride and an organic base is preferable because the polymerization activity can be controlled and the degree of polymerization distribution can be controlled.

Examples of the above hydrogenation catalyst include nickel and laneini.

Kel, Raney copper, copper, zinc, nickel sulfide, cobalt,
Metals such as chromium, rhodium, ruthenium, platinum, and palladium, and oxides, halides, and organometallic complexes of these metals are used. Usually, these hydrogenation catalysts are used in the form of adsorption on the surface of silica, alumina, silica-alumina, zeolite, carbon, etc., which have a large surface area.

The hydrogenation treatment is achieved by bringing the hydrocarbon oil, which is a polymer of the olefin, into contact with a hydrogenation catalyst in an atmosphere containing hydrogen at a predetermined temperature and a predetermined hydrogen partial pressure.

At this time, a solvent such as a saturated hydrocarbon may be used if necessary.

Furthermore, oligomers obtained by hydrogenating polymers such as polybutadiene and polyisoprene synthesized using diolefins such as butadiene and isoprene as olefins can also be used as the base oil. Among these, 1, obtained by living polymerization using an electron transfer compound formed from an alkali metal and an aromatic compound such as naphthalene,
Hydrogenated 2-polybutadiene is preferred because it has high fluidity at low temperatures and increases the low-temperature consistency of the waterproof mixture.

The number average molecular weight of the hydrocarbon oil used in the present invention is 2
A range of 00 to 10,000 is preferable because there is no weight loss or oil separation during heating and high low-temperature consistency is achieved. Among these, hydrocarbon oils having a number average molecular weight of 2000 or less are particularly preferred since they can be used alone as a base oil to provide a waterproof mixture with sufficiently high low-temperature consistency.

In addition, two or more types of hydrocarbon oils used in the present invention may be used in combination. For example, a hydrocarbon oil with a number average molecular weight of more than 2000 can be used in combination with a hydrocarbon oil with a number average molecular weight of 1000 or less to achieve sufficient low-temperature consistency. A waterproof mixture is obtained.

The iodine value of the hydrocarbon oil used in the present invention is 1.2 or less,
It is preferably 0.6 or less. That is, when the iodine value is greater than 1 or 2, the amount of hydrogen generated in the waterproofing mixture increases, increasing the transmission loss of the optical fiber cable.

Next, the thickener, which is an essential component of the present invention, will be explained.

The thickener of the present invention imparts thixotropy, that is, thixotropy, when mixed and kneaded with base oil, and is usually made of organic substances such as metal soap, petrolatum, polyolefin wax, finely ground silica, bentonite, etc. Inorganic substances such as fumed silica and fumed silica are used, but inorganic substances, especially fumed silica, are suitable because the temperature dependence of thixotropy is small.

Fumed silica is an anhydrous ultrafine amorphous particle obtained by burning purified silicon halide such as silicon tetrachloride with oxygen and hydrogen, and usually has a specific surface area of 50 to 500 m"7g and primary particles of 5 to 50 mμ. This fume silica also includes hydrophobic fumed silica treated by reacting the hydroxyl groups on its surface with a silane coupling agent such as dimethyldichlorosilane or trimethylchlorosilane.

The above-mentioned thickener is used in a range of 1 to 80% by weight in the waterproofing mixture, and in particular, for hydrophobic fumed silica, it is used in an amount of 4 to 1% by weight.
6% by weight, and for other fumed silicas, a range of 1 to 10% by weight is preferred in terms of no deterioration in thixotropy or consistency.

Further, the waterproof mixture of the present invention includes a hindered phenol compound which is a derivative of t-butyl-phenol or a derivative of di-t-butyl-phenol; 2.
6. Additives such as antioxidants such as hindered amine compounds that are derivatives of 6-pentamethylpiperidine, phosphite compounds, phosphine compounds, and thioether compounds, antiaging agents, coloring inhibitors, and light stabilizers may be added.

Furthermore, the waterproof mixture of the present invention further includes as a filler:
Inorganic substances such as silica, alumina, calcium carbonate, calcium silicate, talc, aluminum hydroxide, magnesium carbonate, clay, barium sulfate, potassium titanate, diatomaceous earth, and porous or hollow particles composed of these, Teflon, Organic resins such as silicones, polyolefins, and phenolic resins, and porous or hollow particles composed of these may also be added.

Other additives include pigments, dyes, dispersion stabilizers, and the like.

Next, a method for producing the waterproof mixture of the present invention will be explained.

The manufacturing process of the waterproof mixture of the present invention includes, for example, a mixing process in which a thickener and a base oil are mixed in a compatible manner, a kneading process in which a mixture of the thickener and base oil is kneaded to impart thixotropic properties, and a defoaming process. Consists of processes. For the mixing process, a two-shaft mixer has both large blades that gently mix the entire mixing tank and small blades that locally stir the tank at high speed, and a butterfly mixer with a gap in the middle of the blades. Add base oil from a metering pump and thickener from a metering powder feeder to a mixer such as a Nigu, gate mixer, or a mixer with a single or double screw with a spiral groove. An automatic mixing device or the like that automatically supplies each is used.

The kneading step involves applying high shear forces to the base oil mixture to impart thixotropic properties. The equipment used in the kneading process consists of three cylinders, the middle one rotating in the opposite direction to the other cylinders, and the mixture of thickener and base oil passed through the gaps where each cylinder meets and mixed. Three rolls to knead,
A generator-type kneader or the like is used, in which a multilayer comb-like rotor and stator are rotated concentrically, and a mixture of thickener and base oil is passed through the gaps to apply shear force.

Next, waterproofing mixtures have voids, so they may not be able to exhibit sufficient waterproofing functionality, or the bubbles they contain may expand during processing processes that involve high temperatures, such as in loose-tube optical fiber cables, which may interfere with the sheathing process. To prevent this, a defoaming step is required to remove the contained air sacs. The equipment used in the defoaming process includes the three rolls mentioned above, as well as a multilayer disk rotating at high speed in a reduced pressure system. There are multiple stationary plate type defoaming devices.

(Example) Next, the present invention will be explained in more detail by giving examples and comparative examples. Note that parts in the examples are by weight.

Examples 1 to 5 and Comparative Examples 1 to 2 The hydrocarbon oils (A) to (G) shown in Table 1 and the thickener (
1) to (m) and additives (1) to (4) are mixed in the composition shown in Table 2, then kneaded and defoamed to obtain a waterproof mixture. Consistency was measured as follows. The measurement results are shown in Table 2.

In Examples 1 and 2, the thickener and base oil were mixed using a twin-screw mixer, then kneaded using a generator type kneader, and defoamed using a multiple stationary plate type defoaming device. In other examples, the base oil was mixed with a twin-screw mixer and then kneaded with three rolls to defoam.

Further, in Examples 3 to 5 and Comparative Example 2, prior to the mixing step, the base oil was heated to 80°C to dissolve the additives, and then the thickener was mixed.

The amount of hydrogen generated is determined by putting 2 g of a waterproof mixture into a glass Hedsbaine pottle with a capacity of 15 mQ and equipped with a ring packing and a septum cap, and then tightly sealing the mixture at 100°C.
It was left in the oven for 24 hours. After cooling the headspace bottle to room temperature, 2 cQ of the gas in the headspace bottle was sampled using a syringe and subjected to gas chromatography. A calibration curve for the gas chromatograph was prepared in advance under the same conditions and with a known amount of hydrogen. Note that the amount of hydrogen generated in Table 2 indicates the amount of hydrogen generated per 1 g of the waterproof mixture.

The consistency was measured at 23°C and -40°C according to JIS K2220. In addition, -40°C
The consistency was measured after the waterproof mixture and consistency meter were left in a constant temperature room at -40°C for one day and night.

*1) Thickener (I) Hydrophobic fumed silicone surface treated with nidimethyldichlorosilane, BET method specific slope surface area 110±20 *2) Thickener (■): Fumed silicone surface treated with no surface treatment, BET ratio normal surface area 130±25 nm.

*3) tlE (m): ) Hydrophobic fumed silica surface-treated with trimethylchlorosilane, BET method surface area 260±30 *4) Additive (1): Octadecyl-3-(4'-hydroxy-3'5) '-di-t-butylphenyl) flobionate.

*5 Additive (2): Bis(2, 2, 6.
6-tetramethyl-4-piperidyl) sebake *6) Additive (3): Tetrakis(2.4-n-t-butylphenyl)-4.4'-biphenylenephosphonite.

*7) Additive (4): Zinc dibuzardithiocarbamate.

(Effects of the Invention) The waterproof mixture of the present invention can provide a waterproof optical fiber cable with little increase in transmission loss due to hydrogen generation even when used at high temperatures for long periods of time.

Claims (1)

[Claims] 1. A waterproof mixture for filling optical fiber cables containing a base oil and a thickener, wherein the base oil has an iodine value of 1.
A waterproof mixture for filling an optical fiber cable, characterized in that it uses a hydrocarbon oil of 2 or less. 2.Claim 1, wherein the hydrocarbon oil has an iodine value of 0.6 or less
The waterproofing mixture according to claim 1 or 2, wherein the hydrocarbon oil in the waterproofing mixture 3 is hydrogenated. 4. The waterproof mixture according to claim 1 or 2, wherein the hydrocarbon oil is a hydrogenated α-olefin polymer.