JPH01207375A - Composition for water stopping tape and water stopping tape using said composition - Google Patents

Abstract

PURPOSE:To obtain the titled composition suitable for water stopping of optical fiber cable, exhibiting water absorbing performance on pure water, seawater, etc., consisting essentially of a water absorbing and swelling substance component and a binder component comprising a specific crosslinked polyethylene oxide. CONSTITUTION:The aimed composition consisting essentially of (A) a water absorbing and swelling substance component (e.g., starch hydrolyzate of acrylonitrile graft polymer and powder having preferably <=50mum particle diameter) and (B) a binder component comprising a crosslinked polyethylene oxide obtained by crosslinking (i) a polyethylene oxide having >=20,000 average molecular weight with (ii) a bi- or trifunctional crosslinking agent.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a composition for water-stop tape and a water-stop tape using the same.

[Conventional technology]

Water-stop tape is used for various purposes such as water-stopping inside communication cables. Recently, optical fibers have come to be used for communications, and the use of optical fiber cables for water-stopping has also attracted attention. Generally, in optical fiber cables, most cable failures are due to water intrusion into the cable, resulting in adverse phenomena such as deterioration of optical fiber strength and deterioration of transmission characteristics due to freezing.

For this reason, a waterproof material is housed inside the optical fiber cable to provide water-blocking properties. Conventionally, such waterproof materials include sherry materials such as polybutene and petrolactam. However, this type of sherry material is sticky and has poor wiping properties in that it cannot be wiped off without using an organic solvent. This causes deterioration of workability when connecting optical fiber cables, etc.

[Problem that the invention seeks to solve]

In order to solve these problems, attempts have been made to use a water-absorbing swelling tape instead of the sherry material. For example, a water-stopping tape has been considered in which a layer of a water-absorbing swelling substance made of pulp fibers containing powder of a water-absorbing swelling substance of a polymer electrolyte such as a cross-linked polyacrylate is formed on the front and back sides of a plastic film, etc. There is. This water-stop tape has the effect of sealing off water-filled areas by swelling when it comes into contact with water that has entered the cable, and does not have the stickiness and poor wipeability of the Sherry material itself. It has excellent characteristics such as connection workability. However, the water-absorbing swelling substance made of the polymer electrolyte has different water-absorbing properties depending on the water quality, and therefore has a major drawback in that optical fiber cables using it cannot be installed on the coast, the seabed, etc. That is, a water-stop tape using a water-absorbing and swelling substance such as the above-mentioned polyacrylate exhibits a water-absorbing performance of about 300 times as much as fresh water and swells, but it swells in ionized water such as seawater (Na', CI!, -.

Water containing ions such as Ko) exhibits only about 5 times the water absorption performance. Moreover, since the water-absorbing swelling substance such as polyacrylate does not have adhesive properties to the surface of the plastic film, the water-absorbing swelling substance layer is hardened using a binder made of rubber such as ethylene-propylene rubber and synthetic resin. has been made into However, when such a binder is used, since the binder partially or completely covers the particles of the water-absorbing and swelling substance, the effect of this coating becomes significant under ionized water such as seawater, and the water-absorbing and swelling properties of the layer are reduced. inhibited. Therefore, if an optical fiber cable using this cable is installed in a place where seawater or the like may enter, a problem arises in that a sufficient water-stopping effect cannot be obtained when seawater enters the cable.

[Problem that the invention seeks to solve]

The present invention was made in view of the above circumstances, and aims to provide a water-stop tape composition that is easy to handle and exhibits good water absorption and swelling properties even in seawater, and a water-stop tape using the composition. purpose.

[Means for solving problems]

In order to achieve the above object, the present invention has as main components a water-absorbing swelling material component and a binder component made of crosslinked polyethylene oxide obtained by crosslinking component (B) with component (A) below. The first aspect is a composition for water stop tape, which includes (A) polyethylene oxide having an average molecular weight of 120,000 or more;

(B) Difunctional or trifunctional crosslinking agent.

The second aspect is a water-stop tape in which a water-absorbing and swelling material layer is formed using the water-stop tape composition described above.

[Effect]

In the course of repeated research into improving the binder component used for fixing the above-mentioned water-absorbing and swelling substances, the present inventors discovered that, instead of using rubber, synthetic resin, etc. as the binder component, they themselves have water-absorbing and swelling properties. It was conceived that the above-mentioned disadvantages could be avoided by using as a binder a substance whose water absorption and swelling properties are not affected by ionized water such as seawater. As a result of a series of studies to find such a substance, it was discovered that good results could be obtained by using crosslinked polyethylene oxide, which is made by reacting the above components (A) and (B). invention has been achieved. That is, the cross-linked polyethylene oxide itself has water absorption and swelling properties, and the water absorption and swelling properties are not reduced by seawater. This polyacrylate-based water-absorbing swelling substance component and cross-linked polyethylene oxide (
Table 1 shows a comparison of the water absorption capacity of the binder component consisting of PEO) in fresh water and ionic water.

The water absorption capacity was determined by putting the above compound in a beaker, adding water, allowing it to absorb water for a day and night, measuring the weight after water absorption, and comparing it with the weight before water absorption.

However, this polyethylene oxide crosslinked material softens and flows near the upper limit temperature within the cable operating temperature range (-20 to +100'C), so if it is used alone as a water-absorbing swelling material, the temperature near the above-mentioned upper limit temperature will increase. This causes the inconvenience that the water-stop tape itself adheres to the fiber. That is, when the water stop tape is adhered to the optical fiber, the optical fiber cannot move in the axial direction within the cable, so that when the optical fiber expands or contracts due to temperature changes, it causes elongation strain in the optical fiber. The present invention improves the above-mentioned drawbacks of the cross-linked polyethylene oxide by combining cross-linked polyethylene oxide, which has heat-sealability due to such a reduction in melt viscosity, with a water-absorbing swelling substance, and improves the adhesion of the water-stopping tape to the fibers. Moreover, the poor water absorption of seawater of the water-absorbing and swelling substance is compensated for by the crosslinked polyethylene oxide. Note that the cross-linked polyethylene oxide itself has good adhesion to the film-like flexible base material that is the base material of the water-stopping tape, so the water-absorbing swelling substance can be firmly attached to the film-like flexible base material. Can be brought into close contact.

The water stop tape composition of the present invention is obtained using a water-absorbing and swelling substance and crosslinked polyethylene oxide obtained by reacting the components (A) and (B).

The water-absorbing swelling material forming the water-absorbing swelling material layer includes starch, a hydrolyzate of an acrylonitrile graft polymer, a neutralized product of a starch-acrylonitrile acid graft polymer, a hydrolyzate of a vinyl acetate-acrylic acid ester copolymer, or These crosslinked products, hydrolyzed products of acrylamide copolymers, crosslinked products thereof, polyacrylate crosslinked products, and isobutylene-maleic anhydride copolymer crosslinked products are mentioned. These may be used alone or in combination without any problem. These water-absorbing and swelling substances are usually used in powder form.

The above-mentioned crosslinked polyethylene oxide is a polyethylene oxide having an average molecular weight i of 20,000 or more as component (A);
It is obtained by crosslinking the component (B) with a bifunctional or trifunctional crosslinking agent. Generally, polyethylene oxide is insoluble in organic solvents, but as a result of repeated research on such polyethylene oxide, the present inventors found that if its molecular weight and crosslink density are appropriately controlled, it becomes solvent-soluble. I found out.

That is, when the above bifunctional or trifunctional crosslinking agent is subjected to a crosslinking reaction on polyethylene oxide having an average molecular weight of 20,000 or more, the resulting crosslinked polyethylene oxide becomes soluble in various organic solvents. Therefore, using this, the water-absorbing and swelling substance can be turned into a solution and directly coated on a film base material or the like.

Such polyethylene oxide having an average molecular weight of 2,000 or more is not particularly limited, and conventionally used polyethylene oxides can be used as they are.

The water stop tape composition of the present invention can be obtained by powder-mixing the water-absorbing and swelling substance component and the binder component made of the crosslinked polyethylene oxide. In this case, the ratio of the water absorption and swelling component to the binder component made of crosslinked polyethylene oxide is 20 to 500 parts by weight (hereinafter abbreviated as "parts") of the binder component made of crosslinked polyethylene oxide.
From the viewpoint of effectiveness, it is preferable to set the value within the range of . Table 2 below shows the water absorption performance and the like when the mutual mixing ratio of the water absorption swelling component made of the above-mentioned polyacrylate salt and the binder component made of crosslinked polyethylene oxide was changed.

(The following is a blank space) From the table above, it can be seen that the ratio of the water-absorbing swelling component made of polyacrylate-based material to the binder component made of cross-linked polyethylene oxide is preferably cross-linked from the viewpoint of thermal fusion properties.

The water-absorbing and swelling component is in powder form and has a particle size of 5.
It is preferable to set it to 0 μm or less.

That is, by using the above-mentioned water-absorbing and swelling substance in powder form, the water-absorbing and swelling substance having the above particle size is exposed on the surface layer of the water-absorbing and swelling substance layer, thereby reducing the surface friction coefficient of the water-absorbing and swelling substance layer. . Therefore, in a structure where four optical fibers are lined up horizontally in a row, and a tape core wire and water-stop tape are placed side by side, even if external mechanical or thermal forces are applied to the optical fiber cable, the optical fibers and The force applied to the optical fiber in the area where the water tape rubs is reduced, making it less likely that problems such as transmission loss will occur.

The above-mentioned water-stopping tape composition becomes a water-absorbing and swelling material layer of the water-stopping tape by dissolving and dispersing it in a solvent and directly coating the solution on a film-like base material such as a polyethylene terephthalate film.

The water stop tape thus obtained is shown in FIG. In the figure, 1 is a film-like flexible base material, and 2 is a water-absorbing swelling layer. The water-absorbing swelling layer may be formed only on one side of the film-like base material.

In particular, when using the above water stop tape for optical fibers,
The thickness of the film-like flexible base material shown in Figure 1 is 100 μm.
In terms of effectiveness, it is preferable to use a material with a diameter of approximately 50 μm and set the thickness of the water-absorbing and swelling material layer provided thereon to approximately 50 μm.

The film-like flexible base material used for the water stop tape is as follows:
Polyethylene terephthalate film.

Examples include plastic films such as polyethylene film and vinyl chloride resin film. However, there is no problem in using metal foil such as aluminum foil as long as it has flexibility.

The water stop tape of the present invention can be manufactured using the above raw materials, and can be used not only for optical fiber cables but also for various water stop applications. for example,
It can be used as a water-stopping material for underground communication cables, tunnel walls, etc. In particular, those for optical fiber cables can be manufactured as follows.

That is, the width is 1.4 to 2.0 mm and the thickness is 15 to 500 μm.
, preferably by coating (coating, impregnating, etc.) a solvent solution of the crosslinked polyethylene oxide on one or both of the front and back surfaces of a continuous belt-shaped film-like flexible base material of 50 to 200 μm and drying it. Can be done.

The organic solvent for dissolving the crosslinked polyethylene oxide is not particularly limited, and examples include dichloroethane,
Chlorinated solvents such as trichloroethane, n-pentane,
n-octane, benzene.

Examples include hydrocarbons such as toluene and xylene, alcohols such as methyl alcohol and ethyl alcohol, ketones such as acetone 2 and methyl ethyl ketone, and esters such as methyl acetate and ethyl acetate.

The thus obtained water-stop tape for optical fiber cables has a layer of water-absorbing swelling material made of cross-linked polyethylene oxide and water-absorbing swelling material directly formed on one or both of the front and back surfaces of the film-like flexible base material. As a result, it exhibits excellent water absorption performance for both fresh water and ionized water. Therefore, an optical fiber cable using this can be used as a coastline cable, etc., and is not subject to restrictions on installation location. Moreover, since the cross-linked polyethylene oxide has a specific molecular weight and is cross-linked to a predetermined degree of cross-linking using a specific cross-linking agent, it melts and welds to the optical fiber core wire etc. due to changes in the environmental temperature after the optical fiber cable is laid. Problems such as an increase in transmission loss of the optical fiber do not occur. Furthermore, it is easy to manufacture, and cost reduction can be realized through mass production.

Next, examples will be described together with comparative examples.

[Example 1.2, Comparative Examples 1 to 5] First, polyethylene oxide having an average molecular weight of 120,000 or more was prepared, and a crosslinking agent shown in Table 1 below was reacted with this in the proportion shown in the same table to cause crosslinking. Polyethylene oxide was produced. The melting point, solubility in solvents, and water absorption capacity of the obtained crosslinked polyethylene oxide are shown in the same table.

(The following is a margin) No. 3 - Table *l: Shown as weight ratio after immersion in ion-exchanged water for 30 minutes at room temperature. (The preferred magnification range is 20-3
It is 0 times. ) Next, the above-mentioned cross-linked polyethylene oxide (PEO) and a polyacrylate-based water-absorbing resin (manufactured by Sumitomo Chemical Co., Ltd., Sumikagel NP 1010, particle size of 5 μm or less) were added to 100 parts of the cross-linked polyethylene oxide, so that the water-absorbing resin 2
00 parts, and a chlorinated solvent such as dillolethane was added thereto in an amount of 50 to 80 parts by weight to dissolve it. For comparative examples, compounds shown in Table 4 below were used in place of the above PEO. Next, this was applied to both sides of a polyethylene terephthalate film with a thickness of 100 μm and dried to form a water-absorbing swelling layer with a thickness of 50 μm, thereby producing the intended water-stop tape (see FIG. 1).

The water absorption capacity for fresh water and ionic water, as well as thermal fusion properties of the thus obtained water stop tapes were investigated and shown in Table 4 in comparison with comparative examples.

(The following is a blank space) Next, the water-stop tape for optical fiber cable obtained in the above example was incorporated into a water-absorbing waterproof cable. A cross section in that state is shown in FIG. That is, this optical fiber cable 5 has a tension member 6 at the center, and spacers 7 with an outer diameter of 7 m+++ are provided to surround this, and spacers 7 with a width of 1.6 mm and a depth of 1.6 mm are spaced at predetermined intervals around the outer circumference.
Four grooves 8 of 5 nun are formed. One of these
Two optical fiber core wires 10 having a structure in which four optical fibers 9 are accommodated are accommodated in the grooves, one above the other, and the water stop tape 3 for optical fiber cable of the present invention is positioned and disposed between them. There is. Each of the other three grooves accommodates one water-absorbing string (6000 denier) 11 formed of fibers of acrylic acid-acrylate-acrylonitrile copolymer. The first volume is a water stop tape (0.25 m thick, 25 mm wide,
Fabric weight 101g/nf)! This is a 1/4 layered version of 2. Note that 13 is an aluminum tape with a thickness of 0.2 mrrI, and 14 is a polyethylene sheath with a thickness of 1.2 m.

Next, FIG. 3 shows an explanatory diagram of the waterproof test of the above cable. That is, a vinyl vibrator 15 was attached vertically to a 1 m long cable sample 5', water 16 was poured in to a height of 1.2 m, and dissolved water at the end of the cable 5 was observed after 24 hours.

The water-stop tape used for this cable 5 has the ability to absorb water even in seawater, so it can be used with fresh water (distilled water)
Twenty-five cable samples each were tested in artificial seawater and fresh water supplemented with 35 g of NaCl. As a result, no dissolved water was observed in each of the 25 cable samples.

〔Effect of the invention〕

The composition for water stop tape of the present invention has a binder component consisting of a water-absorbing swelling material component and cross-linked polyethylene oxide as its main components, so it has similar resistance to fresh water and ionic water such as seawater. Demonstrates water absorption performance. Therefore, a water stop tape using this has the great advantage of not being restricted by the installation location. In particular, when this is applied to water-stop tape for optical fiber cables, the water-stop tape does not thermally bond to the optical fiber, so expansion and contraction occurs due to temperature changes in the optical fiber environment. Even when the optical fiber is stretched, there is no possibility of unexpected situations such as stretching strain occurring in the optical fiber.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of one embodiment of the water stop tape used in the present invention, and FIG. 2 is a cross-sectional view of the water stop tape of the present invention incorporated into an optical fiber cable. FIG. 3 is an explanatory diagram of a waterproof test of a water stop tape. ■...Film-like flexible base material 2...Water-absorbing and swelling material layer Patent applicant: Sumitomo Electric Industries, Ltd. Tokai Rubber Industries, Ltd., agent Patent attorney: Yukihiko Nishifuji: 11 Diagram 2 Diagram: δ3 diagram

Claims (2)

[Claims] (1) A water-stop tape characterized by having as main components a water-absorbing swelling substance component and a binder component made of cross-linked polyethylene oxide obtained by cross-linking component (B) with component (A) below. Composition. (A) Polyethylene oxide with an average molecular weight of 20,000 or more. (B) Difunctional or trifunctional crosslinking agent. (2) A water-stop tape comprising a film-like flexible base material and a water-absorbing and swelling material layer formed on the surface of the base material, wherein the water-absorbing and swelling material layer is for the water-stop tape according to claim 1. A water stop tape characterized by being made of a composition.