JP5027571B2 - Water-absorbing expandable fiber assembly and method for producing the same - Google Patents

Description

The present invention relates to a fiber assembly that is used for water-stopping tapes, water-stopping packing, and the like and expands by absorbing moisture. In particular, the present invention relates to a water-absorbable expandable fiber assembly that can absorb and expand seawater even in water having a high ion concentration such as seawater.

A pipe joint portion that connects pipes such as cable protection pipes for protecting electric wires and cables buried in the ground is required to have a reliable and sufficient waterproof function and water stop function. As a water-stopping member used in such a part, a non-woven water-stopping member using a water-swellable resin fiber is known, and as such a water-swellable resin fiber, for example, Runseal (registered trademark) Products such as Toyobo Co., Ltd. and Bel Oasis (registered trademark Kanebo Gosei Co., Ltd.) are commercially available.

However, these water-swellable resin fibers are resin fibers mainly composed of polyacrylic acid sodium salt, and exhibit sufficient water-swellability for pure water or water with a low ion concentration (hereinafter referred to as fresh water). However, for water with a high ion concentration such as seawater (hereinafter simply referred to as seawater), the presence of ions inhibits the water-absorbing and expanding properties of the resin. (Hereinafter, these water-absorbing expandable resin fibers are referred to as fresh water expandable resin fibers). Therefore, it is difficult to use these water-stopping members as pipe joints in areas where seawater intrusion is anticipated, and they provide reliable and sufficient waterproofing and water-stopping functions for both freshwater and seawater. There was a need for a water-stopping member that could be used.

Moreover, the resin used for these water-absorbing expandable resin fibers is basically a crosslinked resin, and although it is softened by heating, it does not melt, that is, it is not thermoplastic, so its workability is poor.

On the other hand, there exist a thing as shown by patent document 1 and patent document 2 as a water stop member which can exhibit sufficient water stop effect not only with fresh water but with seawater. In Patent Document 1, a water absorbent resin powder obtained by mixing seawater water absorbent resin powder and pure water absorbent resin powder, an organic binder, and a water absorbent composition composed of an organic solvent are composed of a woven fabric or a nonwoven fabric of synthetic fibers. It is disclosed that a water-stopping tape is manufactured by coating and drying on a substrate and cutting into a tape shape. Patent Document 2 discloses a water-stopping tape in which a composition formed by blending a water-absorbing resin and a foaming agent that generates gas upon contact with water is fixed to a substrate.
JP-A-11-167049 JP 05-314826 A

However, in these water-stopping tapes, the water-absorbing expandable resin powder is supported on the nonwoven fabric by a binder or the like. There was a problem that it was easy to drop off. In order to prevent falling off, it is necessary to increase the amount of the binder. However, if the amount of the binder is large, the water absorption and expansion of the water-absorbing expandable resin is inhibited, and the expansion rate necessary for water stopping cannot be obtained. There was a problem.

In addition, since these water-stopping tapes carry the water-absorbing expandable resin powder with a binder, the tape loses its flexibility and becomes hard, so it is not easy to integrate the water-stopping tape into a pipe joint member or the like. There wasn't.

The present invention provides a water-swellable fiber assembly that exhibits sufficient water-swellability even with respect to seawater, and that the water-swellable resin is less likely to fall out of the fiber assembly and is easy to mold. For the purpose.

The inventors of the present invention, a result of intensive studies, the thermoplastic water-swellable resin having a water-swellable against seawater, by coating a particular substrate the fibers constituting the fiber aggregate, the above problems can be solved As a result, the present invention was completed.

In the present invention, the water-absorbing expandable resin refers to a resin composition that absorbs moisture and expands. The seawater-swelling resin refers to a water-swelling resin that does not lose its water-swellability even when the ion concentration is high, such as seawater. For example, the expansion rate for artificial seawater with a salt concentration of 3% is about 20 times. Say what is. Further, a water-swellable resin that is not a seawater-swellable resin is referred to as a freshwater-swellable resin. The fresh water expandable resin has a sufficient expansion ratio (for example, 150 times) for fresh water having a low ion concentration, while the expansion ratio is low for water having a high ion concentration. On the other hand, the seawater-swelling resin is characterized by having a substantially constant expansion rate in both fresh water and seawater without being greatly affected by the level of ion concentration.

The present invention relates to a water-absorbable expandable fiber assembly used for a water-stop structure, having a water-stop portion that expands by absorbing moisture, and the base fiber of the water-stop portion has a seawater-expandable thermoplastic resin. Is a water-absorbent expandable fiber assembly characterized by being coated (first invention). And in this invention, while the said base fiber is made into the fiber which can absorb a water | moisture content inside a fiber, the fresh water expansible resin fiber is mixed with the said base fiber. And in this invention, a part of surface of a base fiber is coated so that the part which is not coated on the base fiber surface may remain.

Further, the fiber assembly may be a nonwoven fabric (second invention) .

Further, the present invention is a method of forming a water-stopping member using the water-swellable fiber assembly of the first invention, wherein the water-swellable fiber assembly is heated and softened, and then the other member A method for forming a water-stopping member, characterized in that the three-dimensional shape of the water-swellable fiber assembly matches the three-dimensional shape of the other member by conforming to the shape and then cooling (third invention) .

Further, the present invention is a method for adhering the water-swellable fiber assembly of the first invention, wherein the water-swellable fiber assembly is heated to melt the seawater-swelling thermoplastic resin, thereby It is the adhesion | attachment method which heat-welds the water stop part of a property fiber assembly (4th invention) .

According to the present invention, since the base fiber of the fiber assembly is coated with the seawater-swellable resin having water-swellable expandability with respect to seawater, a large surface area of the seawater-swellable resin is ensured, and the expansion rate with respect to seawater is increased. The effect that the water stop effect with respect to can fully be exhibited is acquired. In addition, since the seawater-swellable resin is coated on the base fiber, the seawater-swellable resin is less likely to drop off when handling the water-swellable fiber assembly or when the seawater-swellable resin expands. It is done. Further, since the seawater-expandable thermoplastic resin used in the present invention is thermoplastic, the water-absorbable expandable fiber assembly of the present invention and the coated seawater are heated by heating the seawater-expandable thermoplastic resin of the present invention. The expandable thermoplastic resin can be softened and melted, and the molding process such as integration with a pipe joint can be facilitated.

Furthermore, since the base fiber is a fiber that can absorb moisture inside the fiber, and the base fiber is mixed with a fresh water expandable resin fiber, the expansion rate of the seawater expandable resin can be further increased, and further stopped. The effect that wateriness can be improved is acquired. Furthermore, as the portion not coated on the substrate fiber surface remains in a part of the surface of the substrate fibers have been coated seawater swellable resin Runode, it is smoothly supplied water to the base fiber The water absorption from the base fiber side of the coating layer of the seawater expansion resin coating layer is promoted, and the water absorption expansion performance can be further enhanced.

In addition, according to the third invention , the water-swellable fiber assembly of the present invention can be easily formed into a shape that matches the three-dimensional shape of other components. Moreover, according to the 4th invention , the water absorptive expandable fiber assembly of this invention can be heat-welded.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiment, an embodiment of a water-swellable non-woven fabric will be described by taking as an example the case where a non-woven fabric is used as the fiber assembly. However, the fiber assembly of the present invention is not limited to a non-woven fabric, Paper-made paper or cotton-like fiber aggregates may be used. Further, the shape of the fiber assembly is not limited to a planar shape such as a nonwoven fabric, and may be a string shape, a plate shape, a rod shape, or a block shape. The present invention can be applied to these wide fiber assemblies.

FIG. 1 is a partial cross-sectional view showing the structure of the fibers constituting the water-stop portion of the water-absorbent expandable nonwoven fabric of the present invention. The water-stop part of the water-absorbent expandable nonwoven fabric of the present invention is composed of fibers such that the coating fiber 2 covers the base fiber 1 as shown in FIG. Although the water stop part may be provided in the whole thickness direction and surface direction of the water-absorbent expandable nonwoven fabric, it does not necessarily have to be provided over the whole. When water infiltrates, the water stop portion absorbs and expands and exhibits a water stop effect.

The base fiber 1 constituting the nonwoven fabric of the water stop portion is a fiber for maintaining the shape and function of the nonwoven fabric, and is preferably a synthetic resin fiber, particularly polyester fiber, nylon fiber, polyethylene terephthalate fiber, acrylic Synthetic resin fibers such as fibers and polypropylene fibers can be used. The base fiber 1 may be a poorly hydrophilic fiber such as polypropylene fiber or polyethylene terephthalate (PET) fiber, but is preferably a hydrophilic fiber such as acrylic fiber or nylon fiber. Furthermore, the base fiber is desirably a fiber that can absorb moisture inside the fiber. Furthermore, in order to increase the water absorption of the fiber, a fiber having a hollow structure, a structure having a fine gap, or a fiber that is an aggregate of fine fibers is more desirable. Examples of such water-absorbing fibers include porous fibers such as Biosafe (registered trademark Kanebo Gosei Co., Ltd. product) and Aqua Marble (registered trademark Toyobo Co., Ltd. product). When seawater-swelling thermoplastic resin is coated on the base fiber having such water absorption, water is expanded not only from the outside of the coating layer but also from the base fiber side (inside). Since it is supplied to and absorbed by the heat-resistant thermoplastic resin and the expansion speed thereof is further increased, the water stoppage can be further increased.

Moreover, it is also a preferable embodiment to use the above-described fresh water-expandable resin fiber (for example, run seal or bell oasis) as the base fiber 1. If the fresh water expandable resin fiber is used as the base fiber, the water is supplied and absorbed from the base fiber side to the seawater expandable thermoplastic resin to increase its expansion speed, and for the ingress of fresh water Since the base fiber itself absorbs and expands water, an extremely high water stop effect can be obtained for both seawater and fresh water.

Although the base fiber constituting the nonwoven fabric may be one type, the nonwoven fabric may be configured by blending a plurality of base fibers as described above.

The form of the coating layer 2 in which the base fiber 1 is coated with the seawater-expandable thermoplastic resin is not limited to the form coated on the entire surface of the base fiber 1 as shown in FIG. As shown in FIG. 2, a coating layer 2 ′ in which a part of the surface of the base fiber 1 is coated may be used. Such a coating layer 2 ′ can be easily obtained by applying a seawater-expandable thermoplastic resin dissolved or melted to form a liquid from one side of the nonwoven fabric. In the case of such a coating layer 2 ′, in particular, in order to smoothly supply moisture to the base fiber 1, the coating layer 2 ′ made of seawater-expandable thermoplastic resin from the base fiber side Water absorption can be promoted, and the water absorption and expansion performance of the water absorbent expandable nonwoven fabric of the present invention can be further enhanced. Further, when the base fiber is a water-swellable resin fiber for fresh water, the base fiber is actively absorbed by the fresh water, and the water-swellability for fresh water can be greatly increased.

The coating layer 2 of the present invention is composed of a thermoplastic resin having a sufficient water-absorbing expansibility with respect to seawater (hereinafter referred to as seawater-expandable thermoplastic resin). It has the property of softening and melting when heated.

Examples of the seawater-swelling thermoplastic resin used in the present invention include those containing alkene oxide-modified products as a main component, and even water having a relatively high ion concentration, such as seawater, can be obtained from ions in the solution. Has a feature of selectively absorbing water and exhibiting water-absorbing expansibility. In order for the water-absorbing and expanding nonwoven fabric of the present invention to exhibit an effective water-stopping effect on seawater, the seawater-expanding thermoplastic resin used for the coating layer 2 has a sufficient water-absorbing and expanding property for seawater. The seawater-swelling thermoplastic resin used in the present invention has a water absorption ratio of 20 times or more with respect to artificial seawater having a salt concentration of 3% in which 30 g of sodium chloride is dissolved in 970 g of pure water. Is desirable, more preferably 40 times or more. The water absorption magnification is a weight change magnification obtained by measuring the weight of a predetermined amount of water-swellable resin before and after water absorption and calculating the ratio.

Examples of the seawater-expandable thermoplastic resin applicable to the coating layer of the present invention include Aqua Coke (registered trademark, Sumitomo Seika Co., Ltd. product).

Next, the manufacturing method of the water absorptive expandable nonwoven fabric of this invention is demonstrated. A portion of the raw material nonwoven fabric composed of the base fiber is impregnated with a resin solution in which a seawater-swelling thermoplastic resin is dissolved in a solvent such as toluene, alcohols, aldehydes, or the like. The amount of impregnation can be adjusted by the concentration and amount of the impregnation solution. Further, about 5 to 10% of water may be added to the solvent. The water-stopping portion in which the base fiber 1 constituting the nonwoven fabric is coated with a seawater-expandable thermoplastic resin as the coating layer 2 as shown in FIG. 1 by volatilizing and drying the solvent component from the impregnated nonwoven fabric. The water-absorbable expandable nonwoven fabric can be obtained.

As in this embodiment, when seawater-swelling thermoplastic resin is dissolved in a solvent to form a resin solution, the nonwoven fabric used as a raw material may be one using a base fiber or binder having a relatively low melting point. The water stop portion coated with the seawater-expandable thermoplastic resin as the coating layer 2 can be formed without damaging the nonwoven fabric base fiber and the nonwoven fabric structure.

If the nonwoven fabric is impregnated with the resin solution, as shown in FIG. 1, the entire base fiber 1 can be easily coated, and also the coating can be easily performed over the entire thickness direction of the nonwoven fabric. Therefore, it is possible to reliably prevent a part of the nonwoven fabric in the thickness direction from becoming a water-permeable layer that does not have a water-absorbing expansibility with respect to seawater.

The coating method is not limited to impregnation with a solution of a seawater-expandable thermoplastic resin, and the solution may be applied to a non-woven fabric. In that case, the solution may be applied by an apparatus such as a roll coater or a dispenser.

When the resin solution is applied to the nonwoven fabric, the coating state can be changed over the thickness direction of the nonwoven fabric. For example, by applying a resin solution from one side of the non-woven fabric, one side of the non-woven fabric is used as a waterstop layer in which the base fiber 1 is coated with seawater-expandable thermoplastic resin, and the other side is used as the base fiber. Can be an uncoated raw material nonwoven layer. In such a nonwoven fabric, since the uncoated layer serves as a water-permeable layer for seawater, it is possible to absorb and expand water evenly over the entire surface direction of the water-absorbent expandable nonwoven fabric, and the amount of water absorption is particularly important. It is suitable for application to other applications.

Further, since the seawater-expandable thermoplastic resin used in the present invention is thermoplastic, it can be heated and melted to form a liquid, and the nonwoven fabric is coated and impregnated with the seawater-expandable thermoplastic resin in a molten state. The water-absorbable expandable nonwoven fabric of the present invention can also be obtained. In that case, it is desirable to use a nonwoven fabric using a base fiber or a binder having a relatively high melting point than the melting point of the seawater-expandable thermoplastic resin.

Hereinafter, a method for using the water-absorbent expandable nonwoven fabric of the present invention will be described. The water-absorbent expandable nonwoven fabric of the present invention can be cut into a tape shape and used as a water-stopping tape, for example. Such a water-stopping tape can be used as a water-stopping structural member by winding it around a portion of a pipe or pipe joint member that needs water-stopping, or by forming and integrating it with a pipe or pipe joint member. The water-stopping tape made of the water-absorbent and expandable nonwoven fabric of the present invention absorbs and expands against seawater entering the joint, sealing the gap between the pipe and the pipe joint to obtain a water-stopping effect on seawater Can do.

Further, in the water-absorbing expanded nonwoven fabric of the present invention, since the base fiber is coated with the seawater-expandable thermoplastic resin, it is minimized that the seawater-expandable thermoplastic resin falls off the nonwoven fabric during handling of the nonwoven fabric. It can be suppressed. Furthermore, since the seawater-expandable thermoplastic resin is coated and integrated with the base fiber, it is possible to prevent the seawater-expandable thermoplastic resin from falling apart and falling off the nonwoven fabric even during water absorption.

Furthermore, since the water-swellable non-woven fabric of the present invention is coated with a thermoplastic seawater-swellable resin, the coating layer can be softened or melted by applying heat. Therefore, even if the non-woven fabric may lose its flexibility by being coated with a seawater-swelling resin, the water-swellable non-woven fabric of the present invention can be made warm by heating in an oven or the like. It can be applied to complex shapes such as the outer surface of the end portion of the bellows tube and the inner surface of the connecting portion of the joint for the ribbed tube. Affixing can be performed with an adhesive or a double-sided tape. Then, if the nonwoven fabric is cooled, a water-stopping member molded and integrated can be obtained by adapting well to complicated three-dimensional shapes.

In addition, by heating the water-absorbable expandable nonwoven fabric of the present invention to a temperature equal to or higher than the melting point of the coated seawater-expandable thermoplastic resin, processing such as heat welding can be easily performed. For example, the water-absorbable expandable nonwoven fabric of the present invention is cut into a strip shape, rounded into a cylindrical shape so that both ends thereof overlap each other, and the overlapped portion is heated and pressed at a temperature equal to or higher than the melting point of the seawater-expandable thermoplastic resin. It can weld by this and can manufacture a cylindrical water stop member. Also, the surface of the pipe or pipe joint is heated to the melting point or higher of the seawater-expandable thermoplastic resin, and the water-swellable non-woven fabric of the present invention is pressed on the surface to melt the coating layer, thereby Nonwoven fabric can be welded.

In addition, a resin solution obtained by heating and melting seawater-expandable thermoplastic resin is coated and impregnated into a raw material nonwoven fabric cut into a strip shape into a cylindrical shape using a dispenser, etc. It can also be obtained.

Examples of the present invention will be described below. As a raw material nonwoven fabric, a nonwoven fabric (weighing 300 g / square meter) obtained by blending Lanseal (registered trademark Toyobo Co., Ltd. product), which is a freshwater expandable resin fiber, and polyester fiber in a mixing ratio of 7: 3 was used.

Example 1
Aqua Coke (registered trademark, Sumitomo Seika Co., Ltd. product) was used as the seawater-swelling thermoplastic resin. Aqua coke was dissolved in isopropyl alcohol (IPA) to obtain a resin solution. After impregnating the raw material nonwoven fabric with the resin solution, isopropyl alcohol was volatilized. The seawater-expandable thermoplastic resin was coated on the surface of the base fiber of the raw nonwoven fabric, and the water-absorbable expandable nonwoven fabric of the present invention was obtained. The application amount of aqua coke to the raw material nonwoven fabric was set to 100 g / square meter.

Example 2
Aqua coke was heated to 80 ° C. to dissolve and applied to the raw material nonwoven fabric. By naturally cooling after coating, the seawater-expandable thermoplastic resin was coated on the surface of the base fiber of the raw nonwoven fabric, and the water-absorbent expandable nonwoven fabric of the present invention was obtained. (Aqua coke application amount 150g / square meter)

(Comparative Example 1)
The raw material nonwoven fabric was used as it was as the water-absorbent expandable nonwoven fabric of Comparative Example 1.

(Comparative Example 2)
The raw material nonwoven fabric was coated with a composition prepared by mixing Aqua Coke powder with a binder (product name: Cerny, Nippon Soda Co., Ltd.), dried and supported, and a water-swellable nonwoven fabric of Comparative Example 2 was obtained.

In both Example 1 and Example 2, the base fiber was coated with a seawater-expandable thermoplastic resin, whereby the stiffness of the nonwoven fabric became stronger and the shape retention was improved compared to the raw material nonwoven fabric (Comparative Example 1).

Moreover, the bendability evaluation which presses the water absorption expansion | swelling nonwoven fabric of Example 1, Example 2, Comparative Example 1, and Comparative Example 2 to the bending type | mold with a curvature radius of 5 mm, and bend | folds at 90 degree | times was performed. From any of the water-swellable non-woven fabrics of Example 1, Example 2, and Comparative Example 1, the water-swellable resin was not removed. On the other hand, from the water-absorbing expandable nonwoven fabric of Comparative Example 2, seawater-expanding resin was observed to drop off, particularly from the bent portion.

In addition, when the water-absorbing expanded nonwoven fabrics of Examples 1 and 2 were heated in an oven to 60 ° C., the water-absorbing expanded nonwoven fabric was softened and supple, and could be very easily adapted to a bending mold having a curvature radius of 5 mm. Furthermore, by naturally cooling as it was, it was solidified into a bent shape, and the shape consistent with the bending mold could be maintained. On the other hand, the water-swellable non-woven fabric of Comparative Example 1 was the same as Example 1 and Example 2 of the present invention up to the point where it was adapted to the bending mold, but the shape retention was improved even by natural cooling. There wasn't. The water-swellable non-woven fabric of Comparative Example 2 was not very pliable even when heated to 60 ° C., and was not well adapted to the shape of the bending mold.

(Waterproof)
The water stoppage was evaluated using an apparatus as schematically shown in FIG. The evaluation device has a structure in which the bottom portions of the two water tanks 3 and 4 are communicated with each other through a water stop channel 5. The water stop passage 5 has a rectangular cross section with a width of 50 mm and a height of 1 mm. A water tank 3 in which water (seawater or fresh water) is poured into one water tank 3 after the evaluation sample X cut into a strip shape having a width of 50 mm and a length of 30 mm is installed in this water stop passage with a double-sided tape. The water stoppage was evaluated by applying 0.1 atm from the side and observing the water leaking to the opposite water tank 4 side and the water-absorbing resin being pushed out.

When fresh water was poured into the water tank 3 and pressurized, water leakage to the opposite side was not observed in each of Example 1, Example 2, Comparative Example 1, and Comparative Example 2, and all exhibited sufficient water stopping properties. However, in Comparative Example 2, it was observed that a part of the expanded water-swellable resin powder was pushed out to the water tank 4 side by water pressure. After the test, the water in the water tank 3 was drained and the evaluation sample was once dried, and then the water-stopping evaluation was performed again. In Example 1, Example 2, and Comparative Example 1, water leakage to the opposite side was not observed. However, in Comparative Example 2, the water-absorbing expandable resin was pushed out toward the water tank 4 and water leakage occurred.

When seawater was poured into the water tank 3 and pressurized, in Example 1, Example 2, and Comparative Example 2, water leakage to the opposite side was not observed, and all exhibited sufficient water stoppage. However, in Comparative Example 1, the water could not be stopped, and the seawater flowed into the water tank 4 side. Moreover, in Comparative Example 2, it was observed that a part of the expanded water-swellable resin powder was pushed out to the water tank 4 side by water pressure.

According to the present invention, it can be used as a water-stopping tape or a water-stop packing, and exhibits sufficient water-swelling property, especially for seawater, and the water-swelling resin is less likely to drop off from the member assembly, and is molded. A water-swellable fiber assembly that can be easily processed can be provided.

It is a schematic diagram which shows the structure of the fiber of the water stop part of the water absorptive expandable nonwoven fabric of this invention. It is a schematic diagram which shows the other example of the structure of the fiber of the water stop part of the water absorptive expandable nonwoven fabric of this invention. It is a schematic diagram which shows the outline | summary of the apparatus which performs the water stop evaluation of a water absorptive expandable fiber assembly.

Explanation of symbols

1 Base fiber 2 Coating layer 3 4 Water tank 5 Water stop passage X Evaluation sample

Claims (4)

A water-swellable fiber assembly used for a water-stop structure,
While having a water stop part that absorbs moisture and expands,
The base fiber of the water stop part is coated with seawater-expandable thermoplastic resin,
The base fiber is a fiber capable of absorbing moisture inside the fiber,
The base fiber is mixed with a fresh water expandable resin fiber ,
Part of the surface of the base fiber is coated such that the uncoated portion of the coating remains on the surface of the base fiber . Water-swellable fiber assembly of claim 1, wherein the fiber aggregate is a nonwoven fabric. A method for forming a water-stopping member using the water-absorbent expandable fiber assembly according to claim 1,
After heating and softening the water-swellable fiber assembly,
By adapting to the shape of other members and then cooling,
A method for forming a water-stopping member, wherein the three-dimensional shape of the water-swellable fiber assembly is matched with the three-dimensional shape of the other member. A method for adhering the water-swellable fiber assembly according to claim 1,
Heating the water-swellable fiber assembly to melt the seawater-swelling thermoplastic resin,
An adhesion method in which a water-stop portion of the water-swellable fiber assembly is thermally welded.

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