JPH0641534A - Soil-solidifying agent - Google Patents

Abstract

PURPOSE:To provide a soil-solidifying agent having excellent safety and effective in remarkably improving the solidification rate and the strength of solidified soil. CONSTITUTION:The agent is composed of a copolymer resin of (meth)acrylic acid and a water-soluble (meth)acrylic acid salt containing 30-60wt.% of water- soluble component and 30-90mol% of water-soluble (meth)acrylic acid salt.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention effectively solidifies water-containing soils such as high water-content cohesive soil, sandy soil, sludge, high-organic soil, sludge and silt, or imparts great solidification strength to the ground. The present invention relates to a soil solidifying agent useful for soil reinforcement.

[0002]

[Prior Art] The earth and sand generated during civil engineering work are
Since it contains a large amount of water and is highly fluid, it is extremely difficult to handle, and particularly makes it difficult to carry it out using a belt conveyor or a dump truck. Furthermore, since such soil is used for landfilling, etc., it is necessary to have a compressive strength that allows vehicles such as trucks to pass through. For this reason, various methods for solidifying and stabilizing the water-containing soil have been conventionally investigated. For example, in (a) JP-A-58-187485, a method of mixing a water-absorbent resin with the water-containing soil to reduce free water in the soil. (B) JP-A-64-81886 describes (meth) acrylamide (co).
A method using a water-containing soil solidifying agent composed of a polymer and gypsum has been proposed.

[0003]

However, (a)
However, it is not always satisfactory in terms of solidification strength, and it is not always satisfactory in terms of solidification strength. When it comes into contact with water again due to, for example, it is disintegrated and weakened again. In (b), the acrylamide monomer has a very strong toxicity and is easily absorbed through the skin, so that there is a great risk in producing such a polymer, and the polymerization reaction of acrylamide is insufficient. , Monomer remains and causes poisoning. Furthermore, when polyacrylamide is mixed with soil, there is still concern about the safety after decomposition in the natural world, which is an extremely serious problem. However, it solidifies the water-containing soil very quickly to enable immediate delivery and shows sufficient solidification strength.
Moreover, if we can find a highly safe solidifying agent,
Its significance will be extremely large.

[0004]

However, as a result of intensive studies by the present inventors in order to solve such a problem, the soluble content in water is 30 to 60% by weight, and a water-soluble acrylic acid salt or methacrylic acid is used. Acrylic acid-acrylic acid water-soluble salt copolymer resin or methacrylic acid-methacrylic acid water-soluble salt in which the content of the acid water-soluble salt (hereinafter abbreviated as (meth) acrylic acid water-soluble salt) is 30 to 90 mol% Copolymer resin (hereinafter,
The present invention has been completed by finding that an earth solidifying agent composed of (meth) acrylic acid- (meth) acrylic acid water-soluble salt copolymer resin) is suitable for the purpose. That is, conventionally, a super absorbent polymer used as a soil solidifying agent generally contains 20% by weight or less of a water-soluble component, but surprisingly, it is 30 to 60% by weight. The (meth) acrylic acid- (meth) acrylic acid water-soluble salt copolymer resin containing a highly water-soluble component and having a content of the (meth) acrylic acid water-soluble salt of 30 to 90 mol% is a soil-solidifying agent. It has been found that when used as the above, it exerts an extremely excellent effect of rapidly and effectively solidifying the water-containing soil, which cannot be obtained by the conventional superabsorbent resin. Hereinafter, the present invention will be described in detail.

The (meth) acrylic acid- (meth) acrylic acid water-soluble salt copolymer resin in the present invention means a monomer such as acrylic acid or methacrylic acid (hereinafter simply referred to as (meth) acrylic acid). A polymer or (meth) acrylic acid obtained by partially neutralizing a carboxyl group of a homopolymer or a copolymer obtained by polymerizing with an alkali such as sodium hydroxide, potassium hydroxide or ammonia. Examples thereof include copolymers obtained by copolymerizing with a water-soluble alkali salt. Such copolymers include (meth) acrylic acid or a water-soluble salt of (meth) acrylic acid along with other vinyl monomers such as (meth) acrylic acid ester, unsaturated sulfonic acid or a salt thereof, (meth) acrylamide, (meth)
A small amount of acrylonitrile, vinyl ester, vinyl ether, etc. can be used together.

In carrying out the polymerization, any known method can be adopted, such as aqueous solution polymerization (static polymerization), emulsion polymerization (reverse phase emulsion polymerization), suspension polymerization (reverse phase suspension polymerization) and the like. Either method is possible, but a typical method is reverse phase suspension polymerization or static polymerization. Hereinafter, the polymerization method will be described more specifically. When performing reverse phase suspension polymerization,
An aqueous solution containing (meth) acrylic acid or a water-soluble salt of (meth) acrylic acid is dispersed in an organic solvent that is insoluble in water, and polymerization is performed in the presence of a radical polymerization initiator.

At this time, it is possible to stabilize the polymerization by coexisting with a known dispersion stabilizer or surfactant. Examples of the organic solvent include alicyclic hydrocarbons such as cyclohexane and cyclopentane, aliphatic hydrocarbons such as n-pentane, n-hexane, n-heptane and ligroin, and aromatic hydrocarbons such as benzene, toluene and xylene. To be done. Judging from the boiling point, melting point, price, and industrial availability of the solvent, n-hexane and cyclohexane are the most practical. It is suitable that the polymerization temperature is 50 to 90 ° C. and the polymerization time is 0.5 to 5 hours. After completion of the polymerization, the desired resin is obtained by filtering the produced particles, washing and drying according to a conventional method.

Next, in order to carry out static polymerization, water, (meth) acrylic acid, or a water-soluble salt of (meth) acrylic acid and a radical polymerization initiator are uniformly mixed, and thereafter, stirring and kneading are not performed at all. Polymerization is performed in this state, and the obtained solidified product is crushed and dried. Industrially, the above uniform mixed solution is put in a bucket conveyor, supplied on a belt having weirs at both ends, supplied in a tube, or charged in a container having an arbitrary shape and 40 ~ 100
After kneading at a temperature of about 0 ° C. for 0.03 to 5 hours, polymerization is allowed to proceed while keeping no mixing. The resin solidified product that has reached a predetermined polymerization rate is cut to a size of a pellet or a particle size smaller than that, pulverized and dried. It is desirable to continuously perform this series of operations.

In carrying out the polymerization method as described above,
Examples of the polymerization initiator used include azonitriles such as azobisisobutyronitrile; alkyl peroxides such as t-butyl peroxide and cumene hydroperoxide; dialkyl peroxides such as di-t-butyl peroxide; acetyl peroxide. Amyl peroxide such as oxide, lauroyl peroxide, stearoyl peroxide and benzoyl peroxide; peroxy ester such as t-butyl peroxyacetate, t-butyl peroxyisobutyrate and t-butyl peroxypivalate; methyl ethyl ketone per Examples thereof include oxides, ketone peroxides such as cyclohexanone peroxide, hydrogen peroxide, ammonium persulfate, potassium persulfate, and cerium salts. The amount of the initiator added is 200 to 5 with respect to the total amount of (meth) acrylic acid and the water-soluble salt of (meth) acrylic acid.
000 ppm, preferably 300 to 3000 ppm is used.

Further, it is practically preferable to add a surfactant during the reverse phase suspension polymerization to keep the system stable. Examples of such an active agent include polyoxyethylene alkyl ether, polyoxyethylene acyl ester, polyoxyethylene acyl ester and polyoxyethylene acyl ester. Nonionic surfactants such as oxyethylene sorbitan fatty acid ester, sorbitan fatty acid ester, oxyethylene oxypropylene block copolymer, sucrose fatty acid ester, higher alcohol sulfate ester salt, alkylbenzene sulfonate or polyoxyethylene sulfate,
Alternatively, an anionic surfactant is used alone or in combination.

Thus, the (meth) acrylic acid- (meth) acrylic acid water-soluble salt copolymer resin has a water-soluble content of 30 to
It is essential to control to 60% by weight, preferably 35 to 50% by weight. The soluble component is a combination of the degree of crosslinking of the super absorbent polymer, the degree of polymerization, the content of the water-soluble (meth) acrylic acid salt, the (meth) acrylic acid or the water-soluble (meth) acrylic acid salt and water during the polymerization. It is appropriately adjusted depending on the quantitative compounding conditions with, that is, the monomer concentration or the polymerization temperature. If the water-soluble content is less than 30% by weight, the initial cohesiveness with respect to the soft soil will be poor, and the initial solidification rate will be slow.
When it exceeds 60% by weight, the initial solidification rate is high, but the hardness after solidification decreases. In addition, the soluble component in water in the present invention means a high water-absorbent resin of 0.1 g at 25 ° C. for 24 hours.
It is defined by measuring the resin content in the extract obtained by immersing in g ion-exchanged water and then filtering.

The above-mentioned (meth) acrylic acid- (meth) acrylic acid water-soluble salt copolymer resin further contains (meth) acrylic acid water-soluble salt in an amount of 30 to 90 mol%, preferably 40 to
It is 75 mol%. If the content is less than 30 mol%, the solidification rate of soft soil tends to be slow, and the pH of the soil after solidification tends to decrease. When discarding such solidified soil, it is necessary to adjust the pH to near neutral. Occurs. When it exceeds 90 mol%, both the solidification rate and the solidification hardness decrease,
Furthermore, the pH of the solidified soil tends to be more alkaline, which is not preferable.

(Meth) acrylic acid- (meth) as described above
Acrylic acid water-soluble salt copolymer resin is a polyfunctional compound capable of reacting with the carboxyl group of the resin to partially surface-crosslink to prevent the occurrence of mamako when mixed with hydrous soil. This is advantageous because the excellent solidifying function of the invention can be more effectively exhibited. However, even when surface cross-linking is performed, the water-soluble content is 30 to 60 specified in the present invention.
Needless to say, it is% by weight.

The polyfunctional compound is not particularly limited, but usually, for example, hexane, cyclohexane, benzene,
Since it is used by being dissolved in a hydrophobic solvent such as toluene or a hydrophilic solvent such as water, alcohols such as methanol and ethanol, and ketones such as acetone, it is preferable that the solvent can be dissolved in such a solvent. Specific examples of the polyfunctional compound include, for example, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polyglycidyl ether such as glycerin triglycidyl ether, epichlorohydrin, haloepoxy compounds such as α-methylchlorohydrin, glutaraldehyde. And polyaldehydes such as glyoxal. The method for attaching the polyfunctional compound to the resin of the present invention is not particularly limited, but one example thereof is, for example, a solution of the polyfunctional compound in the solvent is mixed with the resin, and then the solvent is used in a conventional manner. There is a method to get rid of in.

The amount of the polyfunctional compound attached is adjusted to 3 to 100 ppm (weight basis, the same applies hereinafter) or more, preferably 10 to 60 ppm with respect to the resin. When the amount of adhesion is less than 3 ppm, a so-called Mamako phenomenon occurs when it is added to water-containing soil, and the excellent effect of the solidifying agent tends to decrease. If the content exceeds 100 ppm, the water-soluble content of the resin may decrease and deviate from the range specified in the present invention, and the effect of preventing mammoth may reach the ceiling, which is not economically preferable. After this, 20 to 50%, preferably 30 to 40% of water is mixed with the resin, heat treated at 40 to 80 ° C. for 0.5 to 3 hours, and then dried to obtain the desired resin. obtain. In using the solidifying agent of the present invention, if necessary, inorganic powder such as silicon dioxide,
Silica, activated clay, silica sand, diatomaceous earth, perlite,
It is also possible to use an optional component such as bentonite together. The water-containing soil using the solidifying agent of the present invention can be used for any of high water-content specific clay, sandy soil, sludge, highly organic soil, sludge, silt, and any other soil requiring solidification treatment.

In the present invention, the amount of the solidifying agent added is the water content ratio,
Although it depends on the properties of the water-containing soil, it is usually 0.1 to 5 parts by weight, preferably 0.2 to 3 parts by weight, based on 100 parts by weight of the solid content of the water-containing soil. The method of adding the solidifying agent in the present invention is not limited at all, and it is possible to add the solidifying agent all at once, or to add it in several times.

[0017]

[Operation] The soil-solidifying agent of the present invention is excellent in safety and solidifies water-containing soil very quickly to enable immediate transportation, and is also excellent in giving strength to the ground in construction of soft ground. It is a solidifying agent.

[0018]

EXAMPLES Hereinafter, examples of the present invention will be described in detail. Examples 1 to 4, Comparative Examples 1 to 2 100 parts by weight of sandy soil having a water content of 40% by weight (solid content conversion)
The acrylic acid-sodium acrylate copolymer resins shown in Table 1 were mixed with each other to measure the solidification rate of the hydrous soil and the compressive strength of the solidified soil. The results are summarized in Table 2. ○ Measurement method of solidification rate A predetermined amount of water-containing soil was charged into a universal mixing stirrer for mortar, and then a predetermined amount of solidifying agent was added while stirring. After the addition, the time required for the soil to show no fluidity or water-free aggregated state was measured as the setting time. ○ Method for measuring the compressive strength of solidified soil The solidified soil is filled in a mold and solidified,
A columnar type specimen having a diameter of 100 mm and a height of 200 mm, which was not subjected to lateral pressure, was applied to a uniaxial compression tester, and the maximum stress was divided by the cross-sectional area to obtain uniaxial compression strength.

[0019]

[Table 1] Soluble content in water Sodium acrylate Soil solidifying agent (wt%) Content of salt (mol%) Mixing amount (part by weight) Example 1 50 60 0.3 〃 2 30 40 0.6 〃 3 40 70 0.5 0.5 〃 4 60 50 0.3 Comparative Example 1 50 20 0.3 〃 2 80 60 0.3

Example 5 As a polyfunctional compound, 0.005 g of 3,4-epoxycyclohexanecarboxylic acid-3 ', 4'-epoxycyclohexanemethyl ester was used, which was used as cyclohexane 30.
dissolved in g. A cyclohexane solution of the polyfunctional compound was added to 100 g of acrylic acid-sodium acrylate high polymer resin having a water-soluble content of 60% by weight and a sodium acrylate content of 60 mol% using a 1 liter kneader. After addition, cyclohexane was expelled to obtain a resin in which 50 ppm of the polyfunctional compound was attached to the copolymer resin. Next, 40 g of water was mixed, heat treated at 60 ° C. for 1 hour, and further vacuum dried at 90 ° C. for 1 hour. The soluble content of this resin in water was 50% by weight. Using the copolymer resin obtained above, the solidification rate and the compression strength were measured in the same manner as in Example 1. The results are summarized in Table 2.

Example 6 Example 5 except that an acrylic acid-acrylic acid sodium salt copolymer resin having a water-soluble content of 50% by weight and a sodium acrylate content of 70 mol% was used. Surface cross-linking was performed similarly. The soluble content of this resin in water was 40% by weight. The results are summarized in Table 2.

[0022]

[Table 2]

[0023]

Industrial Applicability The solidifying agent of the present invention is excellent in safety and solidifies the water-containing soil very quickly, enables immediate unloading, and has a remarkable effect of having great strength in the soil.

Claims (2)

[Claims] 1. An acrylic acid-acrylic acid water-soluble salt having a water-soluble content of 30 to 60% by weight and a content of acrylic acid water-soluble salt or methacrylic acid water-soluble salt of 30 to 90 mol%. Soil solidifying agent consisting of copolymer resin or methacrylic acid-methacrylic acid water-soluble salt copolymer resin 2. The soil solidifying agent according to claim 1, wherein the resin is partially crosslinked with a polyfunctional compound capable of reacting with a carboxyl group in the molecule.