JPS6041092B2 - Water-swellable composition for water-stopping materials - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a water-swellable resin composition comprising a water-swellable polymeric substance and a thermoplastic resin.

There are various water-swellable materials used as pore water-stopping materials used in civil engineering, construction, and other fields. However, conventional water-swellable materials have problems such as the strength of the swelling column being low and the gel falling off in water, making it difficult to obtain stable performance over a long period of time. There were also products with high gel strength, but they had the drawback of being difficult to mold without using water. Furthermore, it was difficult to prepare a material with an arbitrary degree of swelling. In order to overcome the drawbacks of the conventional water-swellable materials, the inventor of the present invention has conducted extensive research and has discovered that the objective can be achieved by mixing an appropriate amount of thermoplastic resin with a water-swellable polymeric material. Based on this knowledge, the present invention was completed.

That is, in the present invention, for 100 parts by weight of thermoplastic resin,
The present invention provides a water-swellable resin composition, characterized in that it is formed by separating 10 to 300 parts by weight of a finely divided water-swellable solid lower olefin-monohydric maleic acid copolymer crosslinked product. .

The thermoplastic resin in the composition of the present invention provides formability and strength to the crosslinked lower olefin-maleic anhydride copolymer, which cannot be molded into a predetermined shape by itself, and also enables molding using thermoplasticity. Since the thermoplastic resin is blended to make the thermoplastic resin, it can be arbitrarily selected from ordinary thermoplastic resins, and there are no particular restrictions.

Examples of such thermoplastic resins include polyethylene,
Examples include polystyrene, polyvinyl chloride, polybutadiene, polyvinyl acetate, acrylic resin, polyurethane, and polyamide. In addition, not only these homopolymers, but also copolymers of their constituent components or copolymers mainly composed of these constituent components can be used, depending on the use of the composition of the present invention and the required degree of swelling. It is selected as appropriate, taking into account the following. The water-swellable solid lower olefin-oleic anhydride copolymer crosslinked product used in the present invention is a copolymer of a lower olefin and maleic anhydride using a heating agent such as a urea resin or a melamine resin or both. Some are cross-linked.

This crosslinking is preferably carried out to such an extent that the degree of water swelling is in the range of 10 to 200 times. The crosslinked product thus prepared is used in a finely divided state, that is, as a powder. In this case, the lower olefin-maleic anhydride copolymer used as a raw material is a mixture of lower olefins such as ethylene, propylene, n-butene, isobuteso, 1-bentene, 2-pentene, 2-hexene, or a mixture thereof and maleic anhydride. , weight ratio 1:2 to 5:
1, dissolved in a suitable solvent such as dimethylformamide, dimethylacetamide or dimethyl sulfoxide, and polymerized in the presence of a radical polymerization initiator such as persulfate.

Before use, it is advantageous to neutralize this product with an alkali, such as aqueous ammonia, to convert it into a readily water-soluble form. Further, as the urea resin and melamine resin blended as a crosslinking agent, formaldehyde adducts of urea or melamine, condensation products thereof, alkoxy derivatives, etc. are used, and these are preferably those that are easily soluble in water. Further, these may be used alone or as a mixture of two or more. The crosslinking agent is used in an amount of 1 to 10 parts by weight, preferably 5 to 5 parts by weight, per 10 parts by weight of the lower olefin-maleic anhydride copolymer. In this crosslinking reaction for forming a water-swellable polymeric substance, a mixture of a lower olefin-maleic anhydride copolymer and at least one of a urea resin and a melamine resin is mixed with a water swelling degree of 10 to 20.
This is carried out by carrying out a heating reaction until a crosslinked product of M sound is obtained.

At this time, amine salts, metal complex salts, metal compounds, etc. may be added to accelerate the reaction, and blowing agents, anti-aging agents, dyes, pigments, and other fillers may also be added depending on the purpose of use. can. The reaction time required for crosslinking varies slightly depending on the types of components used, composition, reaction temperature, etc., but it is usually sufficient to react at a temperature of about 90°C for 1 to 3 hours.

The water-swellable polymer material thus obtained is pulverized to a particle size of 500 fres or less by conventional means to form a powder.

It may also be divided into flakes. Another example of the water-swellable polymeric substance used in the present invention is
Examples include a hydrogel obtained by crosslinking polyvinyl alcohol in the presence of water, pulverized to a predetermined particle size, and dried.

Crosslinking at this time can be easily carried out either by physical means such as irradiation with electron beams or y-rays, or by chemical means using a crosslinking agent such as glyoxal.

In the composition of the present invention, 10 to 30 parts by weight of a water-swellable polymeric substance is used with respect to 100 parts by weight of a thermoplastic resin,
Preferably 50 to 20 parts by weight are used.

If the latter amount is 1 part by weight, sufficient swelling cannot be obtained when immersed in water, and if it exceeds 30 parts by weight, the strength of the gel will decrease by 4.0 parts, or the gel will fall off. This is so severe that it is impossible to obtain a product that exhibits stable performance over a long period of time. The water-swellable resin composition of the present invention can be molded into various shapes depending on the intended use.

The composition of the present invention has a structure in which a water-swellable polymeric substance is surrounded by a thermoplastic resin which is a hydrophobic substance, and has the following effects. When immersed in water, the thermoplastic resin follows and expands even when it absorbs water and swells, resulting in a swollen body with great strength and very little gel shedding.

By changing the amount of the water-swellable polymeric substance mixed in as appropriate, a product with any desired swelling ability can be obtained.

Thermoplastic resins can be easily molded into various shapes using conventionally known methods. For example, extrusion molding,
Calendar molding, injection molding, etc. can be performed, and there is no need to use water at all. A: Stable performance can be maintained even after repeated swelling and drying. {Ho' At the level of moisture in the air,
It is stable without absorbing moisture, is easy to crush, and is also easy to mix with thermoplastic resins.

When the composition of the present invention is filled into gaps and holes, it swells upon contact with water and prevents the passage of water, so it can be suitably used for water stopping in civil engineering and construction.

Therefore, it is useful, for example, as a seal between segments in tunnel construction, as a seal for a hume pipe connection, as a seal for gaps between external wall panels of a building, as a seal for preventing water leakage, and as a seal for a joint between old and new concrete. Furthermore, the water-swellable resin composition of the present invention can be made into a sheet and used as a water stop layer in soil or as a curing mat for concrete.

Furthermore, it can be used in applications that take advantage of its water-retaining properties, for example, as a long-term blue-retaining sheet that absorbs an aqueous solution of a water-soluble fragrance. Next, the present invention will be explained in more detail based on examples.

Reference example Ammonia neutralized product of isobutylene-maleic anhydride copolymer (manufactured by Kuraray, trade name: Isoban-110) 10
, 1 part by weight of trimethylolmelamine, 1 part by weight of an organic amine salt catalyst, and 300 parts by weight of water,
The reaction was carried out by heating at qo for 1 hour.

In this way, an easily grindable reaction product was obtained. This reaction product was ground in a ball mill for 30 minutes,
The powder accounted for 80% of the 100 mesh passage section. This powder swelled by 15 cm when immersed in water at 20° C. for 1 hour, and did not dissolve even when immersed in water for a long time.

Example 1 180 parts by weight of the water-swellable powder obtained in the reference example was added to 10 parts by weight of the thermoplastic resin, and after thoroughly kneading with a mixing roll, it was formed into a sheet with a thickness of 1.3 willow. The degree of swelling was measured by immersing it in 20 qo water for 2 hours.

Table 1 shows the results for various thermoplastic resins.

Table 1 The sheet swollen in water in this way had a high gel strength.

From the above results, it can be seen that in order to increase the degree of swelling, it is preferable to use a thermoplastic resin that has a large elongation and has a tensile stress of 100%. On the other hand, the sheet-shaped molded product of Experiment No. 1 (1.3 skin thickness) was set in a well-shaped manner between flanges having a gap on two sides, and after being immersed in water for 20 hours to swell, pressurized water was injected. By the way, 20k9/
There was no leakage even under the ground's water pressure.

In this way, stable performance was obtained even when used as a water stop material. Example 2 To 10 parts by weight of ethylene-vinyl acetate copolymer (vinyl acetate component 4% by weight), the water-swelling powder obtained in Reference Example was added in a range of 100 to 18 parts by weight, and A sheet-like molded product was prepared in the same manner as in Example 1, and the degree of swelling was measured.

The results are shown in the table below. Table 2 As shown above, by changing the amount of water-swellable powder, a water-swellable resin composition with arbitrary swelling ability can be obtained, and its swelling and shape have excellent strength. Met.

Example 3 The water-swellable powder obtained in Reference Example was added to 10 parts by weight of various thermoplastic resins in a range of 40 to 8 parts by weight, and the rest was as in Example 1.
A sheet-like molded product was prepared in the same manner as above, and this was heated at 20 o
A compression test was performed on the sample which had been swollen 3 to 6 times by soaking it in water of 0.

The results are shown in the table below. Table 3

Claims (1)

[Claims] 1. A water-swellable resin characterized by blending 10 to 300 parts by weight of a finely divided water-swellable solid lower olefin-maleic anhydride copolymer crosslinked product to 100 parts by weight of a thermoplastic resin. Composition.