JPH02183911A - Water stopping sheet - Google Patents

Abstract

PURPOSE:To obtain improved water stopping capability by forming a resin layer that swells with water on the surface of a sheet-like base material and allowing the resin layer to come off the base material as it absorbs water and swells. CONSTITUTION:A resin layer 2 that swells with water is formed on the surface of a sheet-like base material 1. The layer 2 is made such that it comes off the base material 1 as it absorbs water and swells. Therefore, water invading in a cable 3 (arrow mark) is absorbed by the resin layer 2. Then, as the resin layer 2 swells with water, it comes off the base material 1, clogging a gap 4 within the cable 3 by means of the pressure of invading water (arrow mark) and thereby stopping the movement of water therein immediately. The sheet-like base material 1 can be woven or unwoven cloth of paper or natural fiber, woven or unwoven cloth of synthetic fiber, or a synthetic resin film or sheet of polyester, polypropylene, etc. The resin that swells with water is one which has a number of hydrophilic radicals, such as alkali metal or ammonium salt with carboxyl and sulfone groups, or sub-amine salt group and class 1st to class 3rd amino groups.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a sheet for water running IVJtL, and more specifically to a sheet or tape for use in water running 1F of optical communication cables and electric wire cables.

(Conventional technology and its problems) Conventionally, there are many communication cables such as electric wire cables and optical fiber cables! In recent years, there has been a trend to bury them underground, and they have also been installed in seawater for international communication5. Communication cables installed underground or in seawater are always surrounded by water, so their waterproofness is extremely important.

Conventionally, when the covering material such as the sheath of a communication cable installed underground or in seawater is destroyed due to cracks or pinholes, moisture seeps into the interior, and the water that floods can damage the internal conductors and optical fibers. By running along the
The functionality of communication cables is impaired over long distances.

To solve this problem, in order to prevent water from running inside the communication cable, the cable is filled with water-soluble resin or water-swellable resin powder, or the conductor is covered with water-swellable tape. A method has been proposed for wrapping the

According to this method, the water that floods is absorbed by the water-swellable resin, etc., and the water-swellable resin absorbs water and swells, thereby suppressing the flow of water and reducing the number of damaged parts of the communication cable. You can.

However, it is extremely difficult to uniformly fill powdered water-swellable resin into communication cables that are extremely long and have very narrow gaps, so the most promising method is to wrap water-swellable tape around the core wire bundle. I'm watching.

This water-swellable tape is, for example, one in which a tape base material such as a thin nonwoven fabric is impregnated with a water-swellable R4 resin, or one in which strands or filaments made of water-swellable fibers are woven. It has the disadvantages of slow swelling speed and long water travel distance. In addition, in order to solve this drawback, there is a method in which water-swellable resin is fixed to the surface of the nonwoven fabric using a binder, but in this case, the presence of the binder causes the problem that the water absorption rate is suppressed. be. Furthermore, both of these are present in the cable.
This is insufficient because it takes a long time to completely fill the voids that occur, and the distance water travels is long.

Therefore, an object of the present invention is to provide a water running prevention sheet that solves the above-mentioned problems, particularly a water running prevention Ichikawa sheet that is durable and excellent in water running prevention properties for one cable.

(Means for solving problems) The above objects are achieved by the present invention as described below.

That is, the present invention provides a sheet for preventing water running, characterized in that a water-swellable resin layer is formed on at least one surface of a sheet-like base material, and the resin layer is peelable from the base material when it absorbs water and swells. It is.

(Function) By forming a water-swellable resin layer on at least one surface of the sheet-like base material, and making the resin layer removable from the base material when it absorbs water and swells, water that has entered the cable will swell with water. As the resin layer swells, the swollen resin layer peels off from the base material, and the pressure of the flooded water clogs the gaps inside the cable, immediately preventing water from running inside the cable. be done.

In contrast, in the case of conventional water-swellable sheets, the water-swellable resin layer is fixed to the sheet-like base material, so it takes a long time to completely clog and close the voids in the cable. death,
The water distance will be increased accordingly.

(Preferred Embodiments) Next, the present invention will be specifically explained by citing preferred embodiments.

The anti-water running sheet of the present invention, as shown in the first diagram, has a water-swellable resin layer 2 formed on the surface of a sheet-like base material 1, and the resin layer is made removable from the base material when it absorbs water and swells. by the second
As shown in the figure, the water (arrow) that has entered the cable 3 is absorbed by the water-swellable resin layer 2 and the resin layer 2 swells, and the swollen resin layer 2' is peeled off from the base material 1, and the pressure of the water that entered the cable 3 causes the resin layer 2 to swell. (arrow) indicates that the gap 4 within the cable 3 is clogged 1:1, and water running within the cable 3 is immediately prevented.

The sheet-like base material 1 used in the present invention is, for example,
These are woven fabrics made of paper or natural fibers, woven fabrics made of non-woven fabrics or nonwoven fabrics made of synthetic fibers, or synthetic resin films or sheets made of polyester, polypropylene, polyethylene, etc. These sheet-like base materials should not be very thick in order to be used as a water running prevention tape, for example, a thickness of 0.01 to 1 mm, preferably a thickness of about 0.02 to 0.3+ nm.

These sheet-like base materials may be wide or narrow such as a tape, and are not particularly limited.

When the sheet-like base material is a porous material such as a woven fabric or non-woven fabric, a part of the water-swellable resin layer formed on the surface is impregnated into the woven fabric or non-woven fabric, and the water-swellable resin is impregnated into the woven fabric or non-woven fabric. Since there is a possibility that the releasability of the layer upon water absorption and swelling may deteriorate, it is preferable to form a releasable layer 5 between the water-swellable resin layer 2 to be formed and the sheet-like base material 1, as shown in the third diagram. Therefore, when the sheet-like base material is a non-porous plastic film, such a peeling layer may be omitted.

Sheet J1 (JF on at least one surface of material 1)
The water-swellable nVI resin layer 2 is made of a water-swellable resin.

The water-swellable resin used in the present invention is wood-loving J &
For example, groups of alkali metal salts, ammonium salts, or lower amine salts of carboxyl groups or sulfonic acid groups;
It is a resin containing many groups such as acid salts such as 2.tertiary amino groups, quaternary ammonium groups, and pyridium groups, hydroxyl groups, and ether groups.

Examples of water-swelling 14 resins for use include starch-sodium polyacrylate grafted products, saponified starch-polyacrylonitrile grafted products, cellulose-sodium polyacrylate grafted products, vinyl alcohol-acrylic There are many examples including sodium acid copolymer, vinyl alcohol-sodium methacrylate copolymer, partially crosslinked sodium polyacrylate, and sodium salt of carboxydimethyl cellulose.

Particularly preferred in the present invention is a hydrophobic polymer 3n or a copolymer bonded to a hydrophilic group in the form of a block copolymer or a graft copolymer. For example, if the block is a water-swellable resin, the bonding format is (hydrophobic segment) - (hydrophilic segment) - (hydrophobic segment), and a typical example is , as shown in the example below, (
Thioglycolic acid and
It is obtained by adding or addition polymerizing maleic anhydride, acrylic acid, methacrylic acid, etc. and then neutralizing it with an alkali so that 4'=l.

Another preferable water-swellable resin is a hydrophobic polymer 3n containing α, β-ethylenically unsaturated J, which is graft-copolymerized with 1,000 ml of (meth)acrylic acid as the -L component;
Examples include graft-type water-swellable resins made by forming salts with alkali metals or hydrophilic amines.

A preferred method for forming a water-swellable resin layer from a water-swellable lr1 resin as described below is to disperse the water-swellable resin in a 4F organic solvent, and apply the 3 dispersion liquid to the surface of a sheet-like base material or release layer. This method involves coating and drying.

The fine dispersion of the water-swellable resin as shown below can be obtained by synthesizing the above resin in an organic solvent and neutralizing it with a base if necessary. I1
It may also be dispersed in an organic solvent.

- The organic solvent used in the distribution dispersion is the organic solvent commonly used in the fields of ordinary paints, printing inks, coating agents, etc., such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexane, Any of toluene, xylene, etc. can be used, and the solid content of the water-swellable resin in the dispersion thereof may generally be 5 to 50% by weight. Furthermore, this dispersion contains a binder, an M-type agent, a coloring agent, a fungicide, a conductivity imparting agent, a plasticizer, a process oil,
Carbon black, silica, titanium oxide, antistatic 11-
Optional additives such as abrasives, ultraviolet absorbers, and foaming agents can be added.

By using a binder, the strength of the formed water-swellable resin layer can be improved, but it should not be used too often. If it is used on a sunny day, the water absorption swelling specific speed of the water-swelling resin layer and the peelability of the resin layer will decrease, so use of a binder is prohibited. it is water-swellable resin 1
The amount is 50 parts to 1 part or less, preferably 30 parts by weight or less, per 71 parts of 00Tffj. The most preferable embodiment for increasing the strength of the il-resin layer while minimizing the decrease in water absorption swelling ratio and peelability of the resin layer is to form a water-swellable resin layer containing no binder on the surface of the sheet-like base material or release layer. Furthermore, a water swelling layer containing an appropriate amount of binder is formed on the surface thereof.

Preferred binders include materials that have a small decrease in the rate of water absorption and expansion of the water-swellable resin layer, such as raw rubber, styrene-butadiene rubber, acrylic rubber, urethane rubber, nitrile rubber, ethylene-vinyl acetate, etc. It is the material.

As a method for applying the water-swellable resin dispersion to the surface of the sheet-like base material or the peeling III layer, spraying or methods using various coaters can be used, and the amount applied is 3 to 300 glrd in terms of solid content. That's about it. Thereafter, the sheet for preventing water running of the present invention is obtained by drying.

The water-swellable resin layer as described above may be formed on one side of the sheet-like base material, or may be formed on both sides, or may be formed in a multilayer of two or more layers. In order to increase the surface area of the water-swellable resin layer and improve the rate of water absorption and swelling, it is also preferable to emboss the resin layer, and the embossing treatment also improves the releasability during water absorption and swelling.

In addition, the release layer formed between the sheet-like base material and the water-swellable resin layer, if necessary, also has a sealing effect when a porous material is used as the base material, and the water-swellable resin layer The resin layer is formed from a material that allows water to easily penetrate into the interface with the release layer to improve release properties. Examples of materials for forming such a release layer include polyvinyl chloride, polyvinyl acetate, polyvinyl alcohol, vinyl chloride/vinyl acetate copolymer, ethylene-vinyl acetate copolymer, saponified products thereof, polyethylene, and polypropylene. , polyester, polyurethane, raw rubber, styrene-butadiene rubber, polychloroprene, nitrile rubber, acrylic rubber, nylon, polyvinyl butyral, and other common film-forming materials. These materials may be formed by a coating method or a film lamination method.

Preferred thicknesses range, for example, from about 2 to 50 μm. Of course, it is also preferable to include or apply a release agent such as silicone oil or wax to these release layers.

The water running prevention sheet of the present invention obtained as described above preferably has an overall thickness of about 0.1 to 1 mm.

The waterproof Ichikawa sheet of the present invention as shown in 1=- below can also be used by being cut into a desired shape. For example, if the tape is to be wrapped around a bundle of conductive wires in a cable for waterproofing, a tape shape having a width of about 2 to 200 mm, for example, is preferable.

(Effects) According to the present invention as described above, a water-swellable resin layer is formed on at least one surface of a sheet-like base material, and the resin layer is made removable from the sheet-like base material when it absorbs water and swells. By,
Water that has entered the cable is absorbed by the water-swellable resin layer,
As the resin layer swells, the swollen resin layer peels off from the base material, and the pressure of the flooded water clogs the gaps in the cable, immediately preventing water from running inside the cable, resulting in a short water travel distance. Become.

(Example) Next, the present invention will be explained in more detail by giving examples and comparative examples. In the text, parts or percentages are based on weight unless otherwise specified.

Example 1 About 15 g of polyurethane elastomer (polyether type) with a viscosity of about 200 voids (at 25° C.) was added to a polyester nonwoven 4N (thickness of about 200 μm) with a basis weight of 70 g/ba.
A release layer is formed by coating and drying at a ratio of 25 g/m'' based on solid content, and then coating VIF and drying the water-swellable material A described below at a ratio of 25 g/m'' based on solid content. Further, on the surface thereof, the following water swelling - Bamboo material B was applied at 20 g/m'' (based on solid content) and dried to obtain a sheet material for waterproofing of the present invention.

Fruitful 'tr Example 2 Except for not using water-swellable material B in Example 1 and applying the water-swellable material A at a coating rate of 40 g/ba (based on solid content), the rest was the same as in Example 1. In the same manner as above, a sheet material for preventing water running of the present invention was obtained.

Example 3 The rest was the same as Example 1, except that water-swellable material A in Example 1 was not used and the coating rate of water-swellable material B was 50 g/ba (solid content basis). In the same manner, a waterproof Ichikawa sheet material of the present invention was obtained.

Example 4 A polypropylene film (thickness 30 μm, stretched product) was used as the sheet-like base material in Example 1, and water-swellable material C was inscribed on the surface at a rate of 50 g/ba (solid content basis). It was coated and dried to obtain a sheet material for preventing water running of the present invention.

Example 5 A polyester film (thickness: 50 μm) was used as the sheet-like base material in Example 1, and the following water-swellable material A was applied to the surface at a rate of 20 g/rn'' (based on solid content) and dried. Further, a film of a water-repellent, water-swelling material was bonded to the surface thereof by thermocompression to obtain a sheet material for preventing water running of the present invention.

Comparative Example 1 In Example 1, the following water-swellable material A was coated and dried at a rate of 50 g/rn' (based on solid content) without forming a release layer to obtain a sheet material for preventing water running of a comparative example. Ta.

Comparative Example 2 In Example 1, 50% of the following water-swellable material E was added on the release layer.
g/rn' (based on solid content) and dried to obtain a sheet material for preventing water running of a comparative example. Uniform molecular fit
5.500 polymerizable polystyrene, 10 parts of polymerizable polystyrene having a methacryloyl group at the end, an average Ffi-t of 7. oo.

15.2 parts of one-part polybutyl acrylate, 72 parts of sodium acrylate, 18 parts of acrylic acid and 10 parts of polyethylene glycol dimethacrylate (about 4
50) is dispersed in a mixed solvent of cyclohexane-toluene-methyl ethyl ketone. Average particle diameter is approximately 0.3 μm, solid content is 35%, and water swelling rate is approximately 100 times.

Tomoki Kisai 15% toluene/methyl ethyl ketone (15% toluene/methyl ethyl ketone of acrylic rubber)
1/1) A composition in which 5 parts of the solution was added as solids.

K road n-based tree processing (polystyrene) - (polybutadiene) - (polystyrene) block 1n combination (polystyrene content 30
%) of unsaturated double bonds added with sodium thioglycolate and dispersed in cyclohexanetoluene-dioxane. The average particle diameter is approximately 0.1 to 0.5 μm, solid content is 25%, and water swelling degree is 50 times.

A film (thickness 100 μm) formed by kneading cross-linked sodium acrylate powder (particle size approximately 571 m, water swelling degree approximately 300 times) and chloroprene rubber at a weight ratio of 60 + 40.
.

A composition prepared by adding 70 parts of a 20% solution of a styrene/butadiene copolymer to Material C (30 parts based on solid content).

A groove with a depth of 1.5 mm and a width of 3 mm was formed in the length direction of the surface of an acrylic resin plate having a length of 200 cm.

The water running prevention sheets of Examples and Comparative Examples No. 111 were adhered to these grooves with the water-swellable resin layer facing inside, and a treatment was applied to prevent liquid leakage from the back side. Stand this acrylic plate vertically, and add 1% pure water and 45% sodium chloride from the top of the groove.
% aqueous solution was slowly allowed to flow naturally, and a dew drop was allowed to flow until the liquid no longer flowed out of the container. Thereafter, the water running prevention sheet was peeled off, and the distance between the upper end and the point where the groove was clogged was measured, and the results shown in Table 1 below were obtained.

7, , .

(Water running distance cm) 1% Na (:1 0~3070~90 θ~50 120 70 150~+70 30~60 130 30~50 180 Water does not stop Water does not stop Water does not stop City water does not stop 4 .5%NaC1 100~+10 +80 11-No water, no water stop, no city water, no water stop Example 1 Example 2 Actual Jj6 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Also, The water running prevention sheet of Example 111 has a width of ICl11.
It was cut into tapes and used as waterproof desolation for optical fiber communication cables.

That is, a wound layer of tape made of the anti-water running sheet of the present invention is formed around the central tensile wire, a buffer layer around it, a fiber core arranged around it, and the buffer wire, and then laminated on top of that. An optical communication cable coated with a layer and a sheath was created.

By surrounding the wire of the communication cable with the anti-water running sheet of the present invention in this way, even if the sheath or laminate layer cracks or cracks and water intrudes, the water will be prevented from running. The water-swellable resin layer of the cable sheet is swollen with water, and the expanded layer peels off from the base material and immediately fills the voids in the cable, so no more water can enter the cable.

I actually put a 5m communication cable with the above configuration into water, cut the sheath and laminate layer with a knife, put ``1'' in it, left it for a week, then took it out, peeled off the entire sheath and laminate layer, and examined the inside. However, no water infiltration or water running inside was observed.

For the purpose of comparison, when the water running prevention sheet of the present invention was not used, the entire length of the cable was submerged in water.

[Brief explanation of the drawing]

FIGS. 1 and 3 are diagrams schematically showing the cross section of the water running prevention sheet of the present invention, and FIG. 2 shows the water-swellable resin layer absorbing water and expanding and peeling off, and the water running prevention sheet 11 in the cable. FIG.

Claims (4)

[Claims] (1) A sheet for preventing water running, characterized in that a water-swellable resin layer is formed on at least one surface of a sheet-like base material, and the resin layer is peelable from the base material when it absorbs water and expands. (2) The water running prevention sheet according to claim 1, wherein the water-swellable resin is a Glock or a graft copolymer consisting of a hydrophilic segment and a hydrophobic segment. (3) The water running prevention sheet according to claim 1, wherein a release layer is formed between the sheet-like base material and the water-swellable resin layer. (4) The water running prevention sheet according to claim 1, wherein the resin layer is embossed.