JP2003155475A - Drilling mud additive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a drilling mud additive which permits ready disposal of excavated sediment while hardly exerting adverse effects on the soil environment. SOLUTION: The drilling mud additive, comprising an aqueous dispersion of an alkali-soluble polymer obtained by oil-in-water emulsion polymerization of a monomer composition containing a monomer bearing carboxyl group and/or a salt thereof, is employed for a shield tunneling method and a pipe-jacking method. As the dispersant of the aqueous dispersion of the alkali-soluble polymer is water, there is little risk of soil contamination even when the drilling mud additive containing the alkali-soluble polymer is employed for excavation.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a mud additive suitably used in a shield construction method and a propulsion construction method.

[0002]

2. Description of the Related Art Generally, for example, in a shield construction method suitable for excavating a sand layer, a fine sand layer, a gravel layer, etc., the stability of the cutting face is ensured by injecting a mud additive into the face and applying pressure to the face. It has been practiced to improve the transportability by kneading the above-mentioned mud additive into the earth and sand. Also,
When excavating by the shield method, the cutter provided in the shield device is worn out as the earth and sand are excavated. A mudizing agent is used to reduce the degree of wear of the cutter and to improve the transportability.

Further, for example, in a propulsion method used for laying sewer pipes, a cast iron pipe or a concrete fume pipe is pushed (promoted) into the ground. At that time, the propulsion resistance increases as the propulsion distance of the cast iron pipe or the concrete fume pipe increases. Therefore, mud additives are used to reduce the propulsion resistance.

[0004] As these mud additives, powder mud additives such as carboxymethyl cellulose and superabsorbent resin have been conventionally used. However, since the mud additive is a powder, it tends to scatter and may be inhaled during the work, the solubility / dispersibility is low, and the powders are easily attached to each other to form a powder. There is a problem that it is difficult to pump the body as it is.

Therefore, in order to solve the above problems,
For example, Patent Document 1 discloses a mud additive for a propulsion method in which a water-in-oil type water-soluble vinyl polymer emulsion and a granular superabsorbent resin are added.

Further, for example, Patent Document 2 discloses a mud additive for a shield construction method, which comprises a suspension composition of a spherical or crushed polymer and a water-in-oil emulsion (reverse phase emulsion). There is. Further, for example, in Patent Document 3, in an aqueous dispersion of bentonite and / or clay,
A mud additive for a shield construction method containing a water-in-oil emulsion is disclosed.

[0007]

[Patent Document 1] Japanese Unexamined Patent Publication No. 2000-239483 (publication date: September 5, 2000)

[0008]

[Patent Document 2] Japanese Patent Laid-Open No. 6-117179 (publication date: April 26, 1994)

[0009]

[Patent Document 3] JP-A-60-133084 (publication date; July 16, 1995)

[0010]

However, a water-in-oil emulsion (hereinafter referred to as a reverse phase emulsion) is used as the mud additive used in the shield method and the propulsion method. The inverse emulsion is one in which particles of a water-soluble polymer (water-soluble polymer) are dispersed in an oil phase made of an organic solvent such as paraffin. That is,
Since an organic solvent is used as the dispersion medium, when the reverse phase emulsion is used as a mud additive to excavate by the shield method or the propulsion method, the soil environment is adversely affected (soil is contaminated. ). As described above, the conventionally used reverse-phase emulsion has a high pollution property to the soil environment, and the excavated earth and sand after excavation becomes industrial waste, and therefore its treatment is difficult, and the treatment is difficult. There is a problem that it costs money. Furthermore, since the organic solvent used as the dispersion medium in the reverse emulsion is more expensive than water, there is a problem in that the total cost of the mud additive increases.

The organic solvent, which is the dispersion medium of the reverse phase emulsion, is difficult to handle because it has flammability, and is a target of dangerous substances under the Fire Defense Law.

The present invention has been made in view of the above conventional problems, and an object of the present invention is to provide a mud additive which is easy to treat excavated soil and hardly adversely affects the soil environment.

[0013]

The mud additive of the present invention is a mud additive used in a shield construction method and a propulsion construction method in order to solve the above-mentioned problems.
Alternatively, it is characterized by containing an aqueous dispersion of an alkali-soluble polymer obtained by oil-in-water emulsion polymerization of a monomer composition containing a monomer containing a salt thereof.

The mud additive of the present invention comprises the above monomer composition,
It is more preferable to further include a nonionic monomer having a solubility in water at 20 ° C. of 3% by mass or more.

The mud additive of the present invention comprises the above monomer composition,
It is more preferable to further include another monomer copolymerizable with at least one of the monomer containing the carboxyl group and / or its salt and the nonionic monomer.

In the mud additive of the present invention, the monomer composition contains a monomer containing a carboxyl group and / or a salt thereof in an amount of 10 to 90% by mass, More preferably, the total amount of the ionic monomer and / or the other monomer is contained within the range of 10 to 90% by mass.

In the mud additive of the present invention, the monomer composition contains a monomer containing a carboxyl group and / or a salt thereof in an amount of 30 to 90% by mass. More preferably, the total amount of the ionic monomer and / or the other monomer is contained within the range of 10 to 70 mass%.

In the mud additive of the present invention, the alkali-soluble polymer preferably has a weight average molecular weight of 100,000 or more.

In the mud additive of the present invention, the aqueous dispersion of the alkali-soluble polymer is 1% by mass as the solid content of the aqueous dispersion.
It is more preferable that the viscosity of the aqueous solution within the range of pH 6.8 to 7.2 adjusted to 500 mPa · s or more.

The mud additive of the present invention more preferably contains at least one of an inorganic mineral and a thickener.

According to each of the above constitutions, the mudifying agent used in the shield method and the propulsion method of the present invention contains an aqueous dispersion of an alkali-soluble polymer obtained by oil-in-water emulsion polymerization. Since the dispersion medium of the aqueous dispersion of the alkali-soluble polymer is water, the organic solvent should flow out to the soil as in the case of using a mud additive using a reverse-phase emulsion in which the conventional dispersion medium is an organic solvent. Contamination does not occur. That is, since the contamination of the excavated soil is small, the excavated soil can be treated relatively easily. Therefore, for example, the excavated soil can be reused as a resource without being treated as industrial waste. As a result, the cost of processing the excavated soil can be reduced. Further, since the dispersion medium of the aqueous dispersion of the alkali-soluble polymer is water, the cost is lower than that of the organic solvent used as the dispersion medium of the conventional reverse phase emulsion. Therefore, the mud additive containing the alkali-soluble polymer can reduce the total cost as compared with the conventional mud additive. Further, since the dispersion medium of the aqueous dispersion of the alkali-soluble polymer is water, which is difficult to catch fire, it is highly safe.

Further, the mud additive imparts viscosity to the excavated earth and sand to provide fluidity, so that the excavated earth and sand can be easily transported (conveyed) in the shield construction method and the propulsion construction method.

In the mud additive of the present invention, the monomer containing the carboxyl group and / or its salt is more preferably (meth) acrylic acid.

Further, in the mud additive of the present invention, the nonionic monomer is more preferably methyl acrylate.

In the mud additive of the present invention, the above-mentioned other monomers have a solubility in water at 20 ° C. of less than 3% by mass (meth) acrylic acid ester monomer and a strong acid group-containing unit amount. More preferably, it is at least one of the body monomers.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION An aqueous dispersion of an alkali-soluble polymer contained in a mud additive used in the shield method and the propulsion method according to the present invention is a monomer containing a carboxyl group and / or a salt thereof. It is obtained by oil-in-water emulsion polymerization (hereinafter, simply referred to as emulsion polymerization) of a monomer composition containing In the present invention, the alkali-soluble polymer (hereinafter referred to as polymer) means a polymer obtained by emulsion polymerization of a monomer composition containing a monomer containing a carboxyl group and / or a salt thereof. Show. Aqueous dispersions of the above polymers increase in viscosity by the addition of alkaline substances.

In addition to the monomer containing the above-mentioned carboxyl group and / or its salt, the above-mentioned monomer composition contains a nonionic monomer having a solubility in water at 20 ° C. of 3% by mass or more. (Hereinafter, simply referred to as nonionic monomer)
And / or it is more preferable to contain other monomer copolymerizable with the above monomer (hereinafter, simply referred to as other monomer). The term “copolymerizable with the above monomer” means a monomer containing a carboxyl group and / or a salt thereof, or a monomer containing a carboxyl group and / or a salt thereof and a nonionic monomer. It shows that it can be copolymerized with at least one of the monomers.

Of the above-mentioned monomers containing a carboxyl group and / or a salt thereof, specific examples of the monomer containing a carboxyl group include (meth) acrylic acid, itaconic acid, crotonic acid, Examples thereof include maleic acid and maleic anhydride, but are not particularly limited.
The monomer containing a salt of a carboxyl group is a salt of a carboxyl group-containing monomer, and specifically, for example, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium, barium,
Metal salts of manganese, chromium, iron, cobalt, nickel, copper, zinc, aluminum, tin, lead, silver, cerium, etc .; ammonium salts, hydroxyammonium salts; trimethylamine, triethylamine, monoethanolamine, diethanolamine, triethanolamine, piperidine , Organic amine salts such as pyridine, and the like,
It is not particularly limited. These monomers containing a carboxyl group and / or a salt thereof may be used alone or in combination of two or more. Of the above-exemplified monomers containing a carboxyl group and / or a salt thereof, (meth) acrylic acid is most preferable because it has a good balance between polymerization stability and alkali solubility.

In the present invention, the "nonionic monomer" means a monomer having a solubility in water at 20 ° C of 3% by mass or more. As the nonionic monomer, specifically,
For example, methyl acrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, α-
(Meth) acrylic acid ester monomers such as methyl (hydroxymethyl) acrylate and ethyl α- (hydroxymethyl) acrylate; polyethylene glycol acrylate, polyethylene glycol methacrylate, polyethylene glycol polypropylene glycol polypropylene glycol, polyethylene methacrylate Glycol Polypropylene glycol, isopropenyl oxazoline, polyethylene glycol (2- (1-propenyl) -4-nonyl) phenyl ether, polyethylene glycol (2- (1-propenyl)) phenyl ether, polyethylene glycol-2-propenyl ether, polyethylene glycol -3-methyl-3-butenyl ether, allyl alcohol, polyoxyethylene allyl ether, N-vinyl-
Examples include 2-pyrrolidone and acrylonitrile,
It is not particularly limited. These nonionic monomers may be used alone if necessary, and
You may use 2 or more types together. Among the above-exemplified nonionic monomers, a (meth) acrylic acid ester-based monomer having a good balance between copolymerizability and hydrophilicity is more preferable, and methyl acrylate is most preferable.

As the nonionic monomer, amide type monomers such as acrylamide, methacrylamide and diacetone acrylamide can also be used.

The above-mentioned other monomer means a monomer copolymerizable with at least one of a monomer containing a carboxyl group and / or a salt thereof and a nonionic monomer. The other monomer is not particularly limited, but specifically, a strong acid group-containing monomer or a (meth) acrylic acid ester-based monomer contained in the nonionic monomer. (Meth) acrylic acid ester-based monomer excluding the body, that is, the solubility in water at 20 ° C. is 3% by mass.
And less than (meth) acrylic acid ester-based monomers (hereinafter referred to as other (meth) acrylic acid ester-based monomers).

Specific examples of the strong acid group-containing monomer include vinyl sulfonic acid, (meth) allyl sulfonic acid, 2-sulfoethyl (meth) acrylate, and (meth) acrylic acid-3-sulfo. Unsaturated sulfonic acids such as propyl, 4-sulfobutyl (meth) acrylate, 2-acrylamido-2-methylpropanesulfonic acid, and styrenesulfonic acid, and monovalent metal salts, divalent metal salts, ammonium salts and organic salts thereof. Amine salt; 2- (meth)
Acryloyloxyethyl acid phosphate, 2-
Acid phosphoric acid ester group-containing monomers such as (meth) acryloyloxypropyl acid phosphate, 2- (meth) acryloyloxy-3-chloropropyl acid phosphate, and 2- (meth) acryloyloxyethyl phenyl phosphate; However, it is not particularly limited. These strong acid group-containing monomers may be used alone or in combination of two or more, if necessary. Among the strong acid group-containing monomers exemplified above,
Unsaturated sulfonic acids having good polymerization stability are more preferable, and among them, copolymerizability is good (meth) acrylic acid-
2-sulfoethyl, (meth) acrylic acid-3-sulfopropyl, (meth) acrylic acid-4-sulfobutyl, 2-
Acrylamido-2-methylpropanesulfonic acid, styrenesulfonic acid, and monovalent metal salts, divalent metal salts, ammonium salts and organic amine salts thereof are more preferable, and sodium styrenesulfonate is particularly preferable.

Specific examples of the other (meth) acrylic acid ester-based monomers include ethyl (meth) acrylate, propyl (meth) acrylate, and (meth).
Examples thereof include esters of (meth) acrylic acid such as butyl acrylate and 2-ethylhexyl (meth) acrylate with alcohols having 2 to 18 carbon atoms (excluding cyclic alcohols), and methyl methacrylate. These other (meth) acrylic acid ester monomers may be used alone or in combination of two or more, if necessary. Among the other (meth) acrylic acid ester-based monomers exemplified above, ethyl acrylate is particularly preferable from the viewpoint of the balance between polymerization stability and alkali solubility.

Examples of the other monomer include, in addition to the strong acid group-containing monomer and the other (meth) acrylic acid ester-based monomer, specifically, for example, styrene, α- Styrene-based monomers such as methylstyrene, vinyltoluene, p-methylstyrene, chloromethylstyrene and ethylvinylbenzene; cyclohexyl group-containing monomers such as cyclohexyl (meth) acrylate and cyclohexylmethyl (meth) acrylate; croton Unsaturated esters such as methyl acidate, vinyl acetate and vinyl propionate;
Dienes such as butadiene, isoprene, 2-methyl-1,3-butadiene, 2-chloro-1,3-butadiene;
Monoester of (meth) acrylic acid and polypropylene glycol; methylaminoethyl (meth) acrylate,
Basic monomers such as dimethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, dibutylaminoethyl (meth) acrylate, vinylpyridine, vinylimidazole; etc .; Aziridine group-containing monomers such as (2-) aziridinylethyl (meth) acrylate and (meth) acryloylaziridine; epoxy group-containing monomers such as glycidyl (meth) acrylate and (meth) allylglycidyl ether , Vinyltrimethoxysilane, vinyltriethoxysilane, γ- (meth) acryloylpropyltrimethoxysilane, vinyltris (2-methoxyethoxy) silane, allyltriethoxysilane, etc. Body; vinyl fluoride, vinylidene fluoride, chloride Halogen-containing monomers such as nyl and vinylidene chloride; (meth) acrylic acid, ethylene glycol, polyethylene glycol, 1,3-butylene glycol, diethylene glycol, 1,6-hexanediol, neopentyl glycol, propylene glycol, polypropylene glycol , Trimethylolpropane, pentaerythritol, dipentaerythritol and other polyhydric alcohols, and other polyfunctional (meth) acrylic acid esters having two or more polymerizable unsaturated groups in the molecule; diallyl phthalate, diallylmate , Polyallyl compounds having two or more polymerizable unsaturated groups in the molecule, such as phthalate and diallyl fumarate; polymerizable polyfunctional monomers such as allyl (meth) acrylate, methallyl (meth) acrylate and divinylbenzene Body; Tricia Nure Examples thereof include cyanurates such as G., but are not particularly limited. These may be used alone or in combination of two or more, if necessary.

The above-mentioned other monomer is at least one of the (meth) acrylic acid ester-based monomer and the strong acid group-containing monomer whose solubility in water at 20 ° C. is less than 3% by mass. More preferably.

The polymer in the present invention may be a copolymer of a monomer containing a carboxyl group and / or a salt thereof and the above-mentioned nonionic monomer or other monomer. It may be a copolymer of a monomer containing a salt thereof and / or a salt thereof, the above-mentioned nonionic monomer and another monomer.

The polymer in the present invention includes, as the polymer, a monomer composition containing methacrylic acid and methyl acrylate, or a monomer composition containing methacrylic acid and ethyl acrylate among the above-exemplified monomers. Polymer obtained by polymerizing monomer composition, monomer composition containing methacrylic acid, methyl acrylate and other monomer, or methacrylic acid, methyl acrylate, sodium styrene sulfonate and others A polymer obtained by polymerizing a monomer composition containing the above monomer is more preferable.

When the polymer according to the present invention is a copolymer of a monomer containing a carboxyl group and / or a salt thereof and the above-mentioned nonionic monomer or other monomer, that is, two kinds In the case of copolymerizing (3 types) of monomers, the ratio of the monomer containing the carboxyl group and / or its salt in the monomer composition, that is, the polymer is constituted. The proportion of the monomer containing a carboxyl group and / or its salt in all the monomer units is more preferably in the range of 10 to 90% by mass, and 20 to 20% by mass.
The range of 80 mass% is more preferable, and the range of 30 to 70 mass% is the most preferable. At this time, the proportion of the nonionic monomer or other monomer in all the monomer units constituting the polymer is more preferably in the range of 10 to 90% by mass and in the range of 20 to 80% by mass. Is more preferred,
The most preferable range is 30 to 70% by mass.

More specifically, in the case where the above-mentioned two kinds (three kinds) of monomers are copolymerized, a carboxyl group and / or a salt thereof occupying all the monomer units constituting the polymer. The lower limit value of the monomer containing is more preferably 10% by mass or more, further preferably 20% by mass or more, and particularly preferably 30% by mass or more. On the other hand, the upper limit value of the monomer containing a carboxyl group and / or a salt thereof in all the monomer units constituting the polymer is more preferably 90% by mass or less, further preferably 80% by mass or less, 70 A mass% or less is particularly preferable. At this time, the lower limit value of the nonionic monomer or other monomer in all the monomer units constituting the polymer is more preferably 10% by mass or more, further preferably 20% by mass or more. , 30 mass% or more is particularly preferable. On the other hand, the upper limit value of the nonionic monomer or other monomer in all the monomer units constituting the polymer is more preferably 90% by mass or less, further preferably 80% by mass or less, and 70% by mass. % Or less is particularly preferable. The total ratio of the monomer containing a carboxyl group and / or its salt and the above nonionic monomer is 100% by mass.

When the proportion of the monomer containing the above-mentioned carboxyl group and / or its salt is less than 10% by mass, the polymerization stability is improved, but the alkali solubility and the thickening property of the obtained polymer are lowered. There is. On the other hand, when the proportion of the monomer containing the above-mentioned carboxyl group and / or its salt is more than 90% by mass, the polymerization stability is remarkably reduced, and the obtained polymer may not exist as an aqueous dispersion. is there.

When the polymer according to the present invention is a copolymer of a monomer containing a carboxyl group and / or a salt thereof, the above nonionic monomer and another monomer, that is, three types When (4 types) of monomers are copolymerized, the ratio of the monomer containing the carboxyl group and / or its salt in the monomer composition is 10
To 90 mass% is more preferable, 20 to 80 mass% is still more preferable, and 30 to 70 mass% is most preferable.

More specifically, in the case where the above-mentioned three kinds (four kinds) of monomers are copolymerized, a monomer containing the above-mentioned carboxyl group and / or a salt thereof in the monomer composition is used. The lower limit value of the monomer is more preferably 10% by mass or more, further preferably 20% by mass or more, and particularly preferably 30% by mass or more. On the other hand, the upper limit value of the monomer containing the carboxyl group and / or its salt in the monomer composition is more preferably 90% by mass or less, further preferably 80% by mass or less, and 70% by mass or less. Particularly preferred.

When the proportion of the monomer containing the above-mentioned carboxyl group and / or its salt is less than 10% by mass, the polymerization stability is improved, but the alkali solubility and viscosity increase of the obtained polymer are lowered. There is. On the other hand, when the proportion of the monomer containing the above-mentioned carboxyl group and / or its salt is more than 90% by mass, the polymerization stability is remarkably reduced, and the obtained polymer may not exist as an aqueous dispersion. is there.

The total ratio of the nonionic monomer and other monomers in the monomer composition is 10
To 90 mass% is more preferable, 20 to 80 mass% is still more preferable, and 30 to 70 mass% is most preferable. The total ratio of the monomer containing a carboxyl group and / or its salt, the nonionic monomer and the other monomer is 100% by mass. More specifically, the lower limit of the total amount of the nonionic monomer and the other monomer in the monomer composition is more preferably 10% by mass or more, further preferably 20% by mass or more, 30 A mass% or more is particularly preferable. On the other hand, the upper limit of the total amount of the nonionic monomer and other monomers in the monomer composition is 90% by mass.
The following is more preferable, 80% by mass or less is still more preferable, and 70% by mass or less is particularly preferable.

The above "2 types (3 types)" and "3 types (4 types)" mean a monomer containing a carboxyl group and / or a salt thereof, the above nonionic monomer and other The number of monomers and the number of carboxyl groups and /
Alternatively, the number of monomers containing the salt (the type of monomer containing the carboxyl group and / or the salt) is not particularly limited. Similarly, the number (type) of nonionic monomers and the number (type) of other monomers are not particularly limited.

In order to increase the alkali solubility of the polymer, the monomer composition contains a monomer containing a carboxyl group and / or a salt thereof within the range of 30 to 90% by mass. The nonionic monomer and /
Alternatively, the total amount of other monomers is preferably contained within the range of 10 to 70% by mass.

In addition to these monomers, a chain transfer agent may be used for the purpose of controlling the molecular weight of the polymer or improving the polymerization stability. Specific examples of the chain transfer agent include compounds having a high chain transfer coefficient such as mercapto group-containing compounds such as mercaptoethanol, mercaptopropionic acid, and t-dodecylmercaptan; carbon tetrachloride; isopropyl alcohol; toluene. However, it is not particularly limited. Only one kind of these chain transfer agents may be contained, or two or more kinds thereof may be contained.

The aqueous dispersion of the polymer according to the present invention is obtained by emulsion polymerization. In the emulsion polymerization, the monomer composition is polymerized in the aqueous phase, so that an aqueous dispersion of the above polymer can be easily obtained. The emulsion polymerization can be carried out by a commonly used known method.

The polymerization initiator used in the emulsion polymerization may be any compound capable of decomposing by heat or a redox reaction to generate a radical molecule,
A water-soluble polymerization initiator is more preferable. As the polymerization initiator, specifically, for example, sodium persulfate,
Persulfates such as potassium persulfate and ammonium persulfate;
Water-soluble azo compounds such as 2,2'-azobis- (2-amidinopropane) dihydrochloride and 4,4'-azobis- (4-cyanopentanoic acid); Thermal decomposition initiators such as hydrogen peroxide; Examples of the redox polymerization initiator include a combination of hydrogen peroxide and ascorbic acid, t-butyl hydroperoxide and rongalite, potassium persulfate and metal salts, ammonium persulfate and sodium hydrogen sulfite; Not a thing.
These polymerization initiators may be used alone or in combination of two or more. The amount and type of the polymerization initiator used may be appropriately set depending on the composition of the monomer composition, the polymerization conditions, and the like.

Examples of the emulsifier used in the emulsion polymerization include anionic surfactants, nonionic surfactants, amphoteric surfactants, polymeric surfactants, and reactive surfactants thereof. However, it is not particularly limited. If desired, these emulsifiers may be used alone or in combination of two or more.

Specific examples of the above-mentioned anionic surfactant include alkyl sulfate salts such as potassium dodecyl sulfate, sodium dodecyl sulfate and ammonium lauryl sulfate; polyoxyalkyl ether sulfates such as sodium dodecyl polyglycol ether sulfate. Ester salt; polyoxyethylene carboxylic acid ester sulfuric acid ester salt, polyoxyethylene alkylphenyl ether sulfuric acid ester salt, polyoxyethylene alkyl ether sulfuric acid ester salt, polyoxyethylene phenyl ether sulfuric acid ester salt, polyoxyethylene substituted phenyl ether sulfuric acid ester salt ,
Polyoxypropylene polyoxyethylene alkyl ether sulfate, succinic acid dialkyl ester sulfonate, alkylallyl polyether sulfate, polyoxyethylene alkenyl aryl ether sulfate, α-sulfonato-ω-1- (allyloxymethyl)
Examples thereof include reactive anionic emulsifiers having an unsaturated group such as alkyloxypolyoxyethylene salt, but are not particularly limited. These anionic surfactants may be used alone or in combination of two or more.

Specific examples of the nonionic surfactants include esters of aliphatic and polyhydric alcohols such as glycerin fatty acid ester, glycerol monolaurate, sorbitan fatty acid ester and pentaerythritol fatty acid ester; polyoxyethylene. , Oxyethyleneoxypropylene copolymer, polyoxyethylene alkyl ether, higher alcohol / polyethylene glycol ether, polyoxyethylene alkylaryl ether, polyoxyethylene alkylphenyl ether,
Polyoxynonyl phenyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid monoester / polyethylene glycol condensate, polyoxyethylene sorbitan aliphatic ester, polyoxyethylene alkyl ether glycerin borate ester, polyoxyethylene alkyl ether phosphate ester, ethylene A compound having a polyoxyethylene chain in the molecule, such as a condensate of oxide and an aliphatic amine, an amide or an acid, an alkylamide / polyethylene glycol condensate, an alkylamine / polyethylene glycol condensate, etc., and having surface activity; However, it is not particularly limited. These nonionic surfactants may be used alone,
Moreover, you may use together 2 or more types.

Specific examples of the polymeric surfactant include polyvinyl alcohol and its modified products;
(Meth) acrylic acid-based water-soluble polymer, hydroxyethyl (meth) acrylate-based water-soluble polymer, hydroxypropyl (meth) acrylate-based water-soluble polymer (however, a polymer different from the polymer according to the present invention); Polyvinylpyrrolidone; and the like, but not limited thereto. These polymeric surfactants may be used alone or in combination of two or more.

The polymerization temperature in emulsion polymerization is not particularly limited, but is preferably in the range of 0 to 100 ° C, more preferably 40 to 95 ° C. The total polymerization time is also not particularly limited, but is preferably within the range of 2 to 15 hours. Further, during emulsion polymerization, a hydrophilic solvent, an additive and the like may be added, if necessary, within a range that does not adversely affect the physical properties of the obtained polymer.

The method of adding the monomer composition to the emulsion polymerization reaction system is not particularly limited, and specifically, for example, a batch addition method, a monomer composition dropping method, a pre-emulsion method. , A power feed method, a seed method, a multi-stage addition method and the like can be used.

The concentration of non-volatile components in the aqueous dispersion of the polymer obtained by the above emulsion polymerization reaction is more preferably 60% by mass or less, and further preferably 10 to 50% by mass. The nonvolatile content is 60% by mass
If it exceeds, the viscosity of the above-mentioned aqueous dispersion may become too high, the handling workability may be lowered, or the dispersion stability of the polymer may be deteriorated, whereby the polymers may aggregate.

In order to increase the viscosity remarkably by adding an alkaline substance in a small amount of the aqueous dispersion of the above polymer, it is preferable that the obtained polymer has a high molecular weight. Examples thereof include linear polymers, branched (branched) polymers, crosslinked polymers, and associative polymers. The structures of these polymers are determined by the composition of the monomer composition, the polymerization conditions and the like.

In order to obtain a linear polymer among the above polymers, it is more effective to change the polymerization conditions than to change the composition of the monomer composition. Specifically, for example,
There are methods such as reducing the amount of the polymerization initiator, lowering the polymerization temperature, and / or increasing the polymerization time (dropping time). Further, in order to obtain a branched polymer or a crosslinked polymer, there is a method of adding a polyfunctional monomer such as divinylbenzene. Further, in order to obtain an associative polymer, for example, a method of adding a monomer having an associative hydrophobic group at the terminal via a long-chain hydrophilic portion as a monomer of the third component, etc. is there.

The average particle size of the above-mentioned polymer is not particularly limited, but is preferably within the range of 40 nm to 50 μm, more preferably within the range of 50 nm to 30 μm. If the average particle size of the polymer is less than 40 nm, the viscosity of the aqueous dispersion of the polymer may be too high, the dispersion stability may decrease, and the polymers may aggregate. When the average particle size of the polymer exceeds 50 μm, the polymer may precipitate because the aqueous dispersion of the polymer cannot exist stably.

The weight average molecular weight of the polymer according to the present invention is preferably 100,000 or more, and 100,000 to 200.
The range of 0,000 is more preferable, the range of 500,000 to 20 million is further preferable, the range of 1 million to 20 million is particularly preferable, and the range of 5 million to 20 million is most preferable. When the weight average molecular weight of the polymer is less than 100,000, it becomes difficult to obtain a sufficient viscosity for use as a mud additive for the shield construction method and the propulsion construction method. That is, when the weight average molecular weight of the polymer is 100,000 or more, the mud additive can obtain a sufficient viscosity.
Therefore, by setting the weight average molecular weight of the polymer according to the present invention within the above range, it is possible to prevent the wear of the cutter provided in the shield device and the collapse of the cutting face, and the moisture contained in the mud additive. Can be prevented from escaping, the performance as a mud additive can be further improved, viscosity is added to the excavated earth and sand, and fluidity suitable for the shield construction method and the propulsion construction method is given, so that it can be carried out more easily. The effect that it can be easily performed is obtained.

A mud additive used in the shield method and propulsion method according to the present invention (hereinafter, simply referred to as mud additive)
Contains an aqueous dispersion of the above polymer.

The shield construction method includes muddy water pressure, earth pressure,
There are methods such as open and blind. The mud additive of the present invention is capable of exhibiting a high viscosity even when used in a small amount, and has suitable viscosity and fluidity. Therefore, among the above-exemplified methods, a mud pressure method and a mud type shield method (mud pressure type) It can be used particularly suitably for the shield construction method). Further, the mud additive of the present invention is capable of exhibiting a high viscosity even when used in a small amount, and has suitable viscosity and fluidity, and is therefore suitable for a propulsion method.

The mud additive of the present invention is, for example,
Usually, while excavating the inside of the pipe with an excavator while press-fitting a split-type pipe (steel pipe, concrete pipe, etc.) from the ground, which is the same as the above-mentioned propulsion method, a tubular underground structure (the inside is It can also be used for a construction method for constructing a void, that is, a construction method for constructing an underground structure by press fitting a pipe into the ground.

The mud additive according to the present invention contains an aqueous dispersion of a polymer obtained by oil-in-water emulsion polymerization, and therefore, compared with a conventional mud additive containing a water-in-oil emulsion, Soil pollution can be reduced. That is,
Since the excavated soil containing the mud additive of the present invention has little soil pollution, it can be reused as a resource without treating the excavated soil as industrial waste.

The mud additive according to the present invention may further contain at least one of an inorganic mineral and a thickener (organic thickener).

Specific examples of the above-mentioned inorganic minerals include silt, gravel and the like, sepiolite, attapulgite, entry guide, bentonite, kaolinite, illite, montmorillonite, ectolite, saponite, beidellite, zeolite, palygorska. Light,
Examples include clay minerals such as mica. When these inorganic minerals are contained in the mud additive, only one kind may be contained, or two or more kinds may be contained.

Examples of the thickener include poly (meth) acrylic acid or its salt, polyvinyl alcohol,
Examples thereof include graft copolymers of poly (meth) acrylic acid and polyvinyl alcohol, superabsorbent polymers such as carboxymethyl cellulose sodium salt, methyl cellulose and hydroxyethyl cellulose. The thickener does not include the polymer according to the present invention.

The mud additive of the present invention may contain an antifoaming agent, if necessary. Examples of the defoaming agent include silicone defoaming agents, pluronic defoaming agents, and mineral defoaming agents. By adding the defoaming agent, it is possible to suppress bubbles generated during the use of the mud additive, so that the mud additive can be easily handled.

When the mud additive of the present invention comprises a neutralized aqueous solution of a polymer, the ratio of the polymer contained in the mud additive is 0.01 to 20 when the amount of the mud additive is 100 parts by mass.
The range of mass parts is more preferable, and the range of 0.05 to 10 parts by mass is further preferable. By including the polymer within the above range in the mud additive, it is possible to obtain the same viscosity as that of the conventional mud additive composed of an inverse emulsion. When the ratio of the polymer is less than 0.01 parts by mass,
In some cases, the viscosity of the mud additive becomes low, and the effects of the mud additive exemplified above cannot be obtained. On the other hand, if the proportion of the above-mentioned polymer exceeds 20 parts by mass, the viscosity of the mud additive may become too high, and the viscosity may not be suitable for the shield construction method and the propulsion construction method.

When the mud additive according to the present invention contains a neutralized aqueous solution of a polymer and at least one of an inorganic mineral and a thickener, the ratio of the polymer contained in the mud additive is When the amount of the agent is 100 parts by mass, the range of 0.001 to 10 parts by mass is more preferable, and the range of 0.01 to 5 parts by mass is further preferable. By including the polymer within the above range in the mud additive, it is possible to obtain the same viscosity as that of the conventional mud additive composed of an inverse emulsion.

When the mud additive contains an inorganic mineral, the proportion of the inorganic mineral is such that the mud additive is 100 parts by mass.
The amount is preferably 50 parts by mass or less, more preferably 0.5 to 30 parts by mass. 50% of the above inorganic minerals
When it exceeds the mass part, the viscosity of the mud additive becomes too high, which may result in a viscosity not suitable for the shield construction method and the propulsion construction method.

When the above-mentioned thickening agent contains a thickening agent, the proportion of the thickening agent is preferably 30 parts by mass or less, more preferably 0.01 to 20 parts by mass, based on 100 parts by mass of the thickening agent. The range is more preferable. When the proportion of the thickening agent exceeds 30 parts by mass, the viscosity of the mud additive becomes too high, and the viscosity may be unsuitable for the shield construction method and the propulsion construction method.

The aqueous dispersion of the polymer according to the present invention (and the mud additive containing the same) has an increased viscosity in the alkaline region and a reduced viscosity in the acidic region.

When an alkaline substance is added to the above-mentioned water dispersion, that is, when excavating by a shield method or a propulsion method using a mud additive containing the water dispersion, the muddy water to which the alkaline substance is added is added. The pH is not particularly limited, but pH 6 or higher and pH 1
It is more preferably less than 3. The pH of the muddy water is 6
If it is less than the above range, the aqueous dispersion may not be able to obtain a desired viscosity. Also, the pH of the muddy water is 13
In the above cases, the aqueous dispersion may gel.

Specifically, for example, an aqueous solution (dispersion liquid) of a mudifying agent containing 1% by mass of a polymer at pH 7.
The viscosity of is more preferably 100 mPa · s or more. In addition, the viscosity of the aqueous solution of the mud additive containing 1% by mass of the polymer at pH 4 is more preferably 10 mPa · s or less.

More specifically, for example, the aqueous dispersion of the alkali-soluble polymer contained in the mud additive of the present invention is
PH 6 adjusted to 1% by mass as the solid content of the aqueous dispersion.
The viscosity of the aqueous solution within the range of 8 to 7.2 is 100 mP.
It is more preferably a · s or more, and 500 mPa · s
s or more is more preferable, 800 mPa · s
The above is particularly preferable, and 1000 mPa · s or more is most preferable. The viscosity is within the range of 22.5 to 24.5 ° C. in the temperature of the aqueous solution, and the B-type viscometer (viscosimeter type BM), rotor No. 3 is the value measured under the condition that the rotation speed of the rotor is 60 (min ⁻¹ ).

On the other hand, the aqueous dispersion of the alkali-soluble polymer contained in the mud additive of the present invention has a pH within the range of 6.8 to 7.2 adjusted to 1% by mass as the solid content of the aqueous dispersion. The upper limit of the viscosity of the aqueous solution is not particularly limited depending on the environment used, the type of soil, etc.
More preferably 0000 mPa · s or less, 100,000
It is more preferably mPa · s or less. The above upper limit value refers to "the viscosity of the neutralized aqueous solution when the solid content concentration is 1% by mass". Also, the viscosity is 1
When the viscosity exceeds 00000 mPa · s, a B-type viscometer (viscosimeter type BH) is used as a viscometer for measuring viscosity, and the temperature of the aqueous solution is within a range of 22.5 to 24.5 ° C., for example, , Rotor No. 7, the rotation speed is 2 (m
It may be measured under the condition of (in ⁻¹ ). Also, the viscosity is 100
A viscosity of 000 mPa · s or less (specifically, for example, 1
(Within a viscosity range of 000 mPa · s to 100,000 mPa · s), using a B-type viscometer (viscometer model BM),
When the temperature of the aqueous solution is within the range of 22.5 to 24.5 ° C., for example, the rotor No. 4, the rotation speed is 6 (min ^-1 )
It may be measured under the conditions of.

Specific examples of the alkaline substance include sodium hydroxide, potassium hydroxide, sodium carbonate, sodium hydrogen carbonate, ammonium carbonate,
Examples thereof include ammonium hydrogen carbonate, ammonia (water), amines and the like.

As described above, the mud additive according to the present invention is
A mudifying agent used in a shield construction method and a propulsion construction method, which contains an aqueous dispersion of a polymer obtained by emulsion polymerization of a monomer composition containing a monomer containing a carboxyl group and / or a salt thereof. is doing.

Therefore, it is possible to obtain a mud additive having a viscosity suitable for the shield construction method and the propulsion construction method, and it is possible to prevent wear of the cutter provided in the shield device and collapse of the cutting face. It is possible to prevent the escape of water contained in the sand, improve the performance as a mud additive, and to give the excavated soil a viscosity that allows it to be easily carried out. Is obtained.

Further, since the dispersion medium of the aqueous dispersion of the polymer is water, the soil is less polluted as compared with the case of using the conventional mud-adding agent using an inverse emulsion. That is, as compared with the conventional mud additive, in which the dispersion medium is an organic solvent, the pollution of the excavated soil is less. Therefore, for example, the excavated soil can be reused as a resource without being treated as industrial waste. Moreover, since the dispersion medium of the polymer aqueous dispersion according to the present invention is water, the cost is lower than that of the organic solvent used as the dispersion medium of the conventional reverse phase emulsion.
Therefore, the mud additive according to the present invention can reduce the total cost as compared with the conventional mud additive.

Further, the dispersion medium of the water dispersion of the polymer is water, which is hard to catch fire, and therefore the mud additive of the present invention is highly safe.

In the shield construction method and / or propulsion construction method, the mud liquid (mud water / mud) used in these construction methods is used in other construction methods such as the underground continuous wall construction method and the cast-in-place pile construction method. It is important that the viscosity is higher than that of the mud. Therefore, among the mud additives of the present invention, for example, a mud additive used in a shield construction method and a propulsion construction method, in which a monomer composition containing a monomer containing a carboxyl group and / or a salt thereof is prepared in water. An aqueous dispersion of an alkali-soluble polymer obtained by oil-type emulsion polymerization is contained, and the monomer composition contains a carboxyl group and / or a salt thereof in an amount of 10 to 90% by mass. Used in the shield construction method and the propulsion construction method, in which the total amount of the nonionic monomer and / or the other monomer is contained in the range of 10 to 90% by mass. A mud additive, which comprises an aqueous dispersion of an alkali-soluble polymer obtained by oil-in-water emulsion polymerization of a monomer composition containing a monomer containing a carboxyl group and / or a salt thereof. , In the above monomer composition , A carboxyl group and / or a monomer containing the salt 30-9
It is contained within the range of 0% by mass, and the total of the above-mentioned nonionic monomer and / or other monomer is contained within the range of 10 to 70% by mass, or the shield construction method and promotion. A mudifying agent used in the method, which is an aqueous dispersion of an alkali-soluble polymer obtained by oil-in-water emulsion polymerization of a monomer composition containing a monomer containing a carboxyl group and / or a salt thereof. When the aqueous dispersion of the alkali-soluble polymer is contained, the aqueous solution has a viscosity of 500 mPa · s or more within a pH range of 6.8 to 7.2 adjusted to 1% by mass as the solid content of the aqueous dispersion. By having a certain configuration, in the case of the same addition amount as compared with conventional ones and mud additives of other configurations included in the present invention, specifically,
When added so that the solid content concentration becomes the same, the obtained viscosity can be made sufficiently high. Therefore, the mud additive having the above structure is suitable for the shield construction method and / or the propulsion construction method.

A mudifying agent used in the shield method and the propulsion method, which is obtained by oil-in-water emulsion polymerization of a monomer composition containing a monomer containing a carboxyl group and / or its salt. An aqueous dispersion of an alkali-soluble polymer is contained, and the monomer composition containing a carboxyl group and / or a salt thereof in an amount of 30 to 9 is contained in the monomer composition.
It is contained in the range of 0% by mass, and the total amount of the nonionic monomer and / or other monomer is 10 to 10%.
An aqueous solution containing 70% by mass of the aqueous dispersion of the alkali-soluble polymer and having a pH of 6.8 to 7.2 adjusted to 1% by mass as a solid content of the aqueous dispersion. The viscosity of the mud additive having a viscosity of 500 mPa · s or more is the same as that of the conventional mud additives or the mud additives of other components included in the present invention, so that the solid content concentration is the same. The viscosity obtained is very high. That is, among the mud additives of the present invention, the viscosity required for the mud used in the shield construction method and / or the propulsion construction method can be adjusted to the conventional one or another constitution included in the present invention by adopting the above constitution. It can be achieved with a smaller addition amount as compared with the mud-adding agent. Therefore, the mud additive having the above structure is most suitable for the shield construction method and / or the propulsion construction method.

Further, since the mud additive according to the present invention is excellent in salt resistance, for example, even when it is used when excavating a salt-containing formation (soil) such as seawater, the viscosity is rapidly reduced. Absent. Therefore, the mud additive according to the present invention can be suitably used even when excavating a formation (soil) containing salt such as seawater as compared with the conventional mud additive.

[0086]

The present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these. In the examples and comparative examples, "part" means "part by mass" and "%" means "% by mass".

[Production Example 1] A flask equipped with a dropping funnel, a stirrer, a nitrogen gas introducing tube, a thermometer and a reflux condenser was charged with 326.1 parts of ion-exchanged water and Hitenol N.
-08 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) and 2.9 parts were charged. Next, the air in the flask was replaced with nitrogen gas while the liquid temperature in the flask was raised to 75 ° C. while stirring.

On the other hand, 102.2 parts of methacrylic acid and 189.8 parts of methyl acrylate were vigorously added to an emulsifier aqueous solution prepared by dissolving 5.8 parts of Hitenol N-08 in 276.2 parts of ion-exchanged water. A pre-emulsion was prepared by stirring, and the pre-emulsion was placed in a dropping funnel.

Next, 57.4 parts of the above pre-emulsion was added all at once to the aqueous solution in the flask, and the mixture was stirred for 5 minutes while keeping the liquid temperature at 75 ° C. Next, after introducing 3.0 parts of a 1% sodium hydrogen sulfite aqueous solution and 6.7 parts of a 1% ammonium persulfate aqueous solution into the flask, the internal temperature was adjusted to
That is, the liquid temperature in the flask was raised to 77 ° C., and initial polymerization was carried out for 20 minutes while stirring.

Thereafter, while maintaining the liquid temperature in the flask, that is, the reaction temperature at 77 ° C., the remaining 516.6 parts of the above pre-emulsion and 1% ammonium persulfate aqueous solution 6 were added.
The addition of 0.3 part was started at the same time, and the rest of the pre-emulsion was added dropwise for 2 hours and 1% ammonium persulfate aqueous solution over 3 hours. After the dropping of the pre-emulsion was completed, the dropping funnel was washed with 10.0 parts of ion-exchanged water, and this washing liquid was put into the flask. Next, after the addition of the 1% ammonium persulfate aqueous solution was completed, polymerization was performed for another 30 minutes, then 17.0 parts of a 1% Rongalit aqueous solution was added dropwise as a post-addition catalyst over 30 minutes, and after the addition was completed, polymerization was performed for another 30 minutes. It was After cooling the obtained reaction solution,
The polymerization was completed. Then, an oil-in-water alkali-soluble emulsion having a nonvolatile content concentration of 29.6% was obtained.

[Production Example 2] In a flask equipped with a dropping funnel, a stirrer, a nitrogen gas introducing tube, a thermometer and a reflux condenser, 311.6 parts of ion-exchanged water and 20% Hitenol N-08 (first) 14.6 parts manufactured by Kogyo Seiyaku Co., Ltd. Next, the temperature of the liquid in the flask was raised to 70 ° C. with stirring, and then the air in the flask was replaced with nitrogen gas.

On the other hand, 101.9 parts of methacrylic acid and 189.8 parts of methyl acrylate were mixed with 20% hythenol N--.
29.1 parts of 08 was added to an emulsifier aqueous solution dissolved in 316.7 parts of ion-exchanged water and vigorously stirred to prepare a pre-emulsion, and the pre-emulsion was placed in a dropping funnel.

Next, 63.7 parts of the above pre-emulsion was added all at once to the aqueous solution in the flask, and the mixture was stirred at 70 ° C. for 10 minutes. Next, after pouring 3.0 parts of a 1% sodium hydrogen sulfite aqueous solution and 6.8 parts of a 1% ammonium persulfate aqueous solution into the flask, the internal temperature, that is, the liquid temperature in the flask was 70 ° C., and stirring was continued for 20 minutes. Initial polymerization was carried out.

Thereafter, while maintaining the liquid temperature in the flask at 70 ° C., the remaining 573.3 parts of the above pre-emulsion was mixed with 3 parts.
It dripped over time. After the dropping of the pre-emulsion,
The dropping funnel was washed with 10.0 parts of ion-exchanged water, and the washing solution was put into the flask. After polymerizing for another 30 minutes, 17.0 parts of a 0.1% Rongalit aqueous solution was added as a catalyst as a post-addition catalyst, and the polymerization was further performed for 60 minutes. After cooling the obtained reaction liquid, the polymerization was completed. Then, an oil-in-water type alkali-soluble emulsion having a nonvolatile content of 28.2% was obtained.

[Production Example 3] In a flask equipped with a dropping funnel, a stirrer, a nitrogen gas introducing tube, a thermometer and a reflux condenser, 253.5 parts of ion-exchanged water and 20% Hitenol N-08 (first) 14.6 parts manufactured by Kogyo Seiyaku Co., Ltd. Next, the temperature of the liquid in the flask was raised to 70 ° C. with stirring, and then the air in the flask was replaced with nitrogen gas.

On the other hand, 101.9 parts of methacrylic acid and 189.3 parts of methyl acrylate were mixed with 20% hythenol N--.
29.1 parts of 08 was added to an emulsifier aqueous solution dissolved in 316.7 parts of ion-exchanged water and vigorously stirred to prepare a pre-emulsion, and the pre-emulsion was placed in a dropping funnel.

Next, 63.7 parts of the above pre-emulsion was added all at once to the aqueous solution in the flask, and the mixture was stirred at 70 ° C. for 10 minutes. Next, after introducing 3.0 parts of a 1% sodium hydrogen sulfite aqueous solution and 6.8 parts of a 0.1% ammonium persulfate aqueous solution into the flask, the internal temperature, that is, the liquid temperature in the flask was 70 ° C. for 20 minutes,
Stirring was continued to carry out initial polymerization.

Then, while maintaining the temperature of the liquid in the flask at 70 ° C., the dropwise addition of the remaining 573.3 parts of the pre-emulsion and 61.5 parts of a 0.1% ammonium persulfate aqueous solution was started at the same time, and 3 parts of each of them were added. It dripped over time.
After the completion of dropping the pre-emulsion, deionized water 10.0
The dropping funnel was washed using a part, and the washing solution was put into the flask. After the pre-emulsion and the 0.1% ammonium persulfate aqueous solution were added dropwise, the mixture was polymerized for another 30 minutes, and then 6.8 parts of a 0.1% sodium hydrogen sulfite aqueous solution was added at once as a post-added catalyst. .1
% Aqueous sodium hydrogen sulfite solution (6.8 parts) was added all at once. Then, after the second addition of 0.1% sodium hydrogen sulfite aqueous solution, polymerization was carried out for 120 minutes while maintaining the liquid temperature in the flask at 70 ° C. The obtained reaction liquid was cooled to complete the polymerization, and an oil-in-water alkali-soluble emulsion having a nonvolatile concentration of 29.4% was obtained.

Example 1 The emulsion obtained in Production Example 1 was mixed with a 3% aqueous sodium hydroxide solution and ion-exchanged water at the ratios shown in Table 1 below, and the solid content concentration of the alkali-soluble polymer was changed. A neutralized aqueous solution having a concentration of 0.5, 1, 2, 3 and 5% was prepared.

[0100]

[Table 1]

The solid content concentration is 2, 3 and 5
% Of each neutralized aqueous solution, the pH immediately after preparation was measured, and the rotor-NO. 3 using 25 ℃, rotation speed 60min ^-1
The viscosity was measured under the conditions of. The results are shown in Table 2.
As the measurement value of the B-type viscometer, the viscosity at the time when the rotor was rotated for 1 minute was read and used as the measurement value.

[0102]

[Table 2]

Example 2 The emulsion obtained in Production Example 2 was mixed with a 3% aqueous sodium hydroxide solution and ion-exchanged water at the ratios shown in Table 3 below, and the solid content concentration of the alkali-soluble polymer was changed. A neutralized aqueous solution having a solid content concentration shown in Table 1 was prepared.

[0104]

[Table 3]

The solid content concentration is 0.5, 1,
For 2, 3 and 5% neutralized aqueous solutions, p
H was measured, and the viscosity was measured under the same conditions as in Example 1 using a B-type viscometer (same as above). The results are shown in Table 4.

[0106]

[Table 4]

[Comparative Example 1] As a comparative example, a reverse phase emulsion (trade name; Invertex AR-25; manufactured by Toagosei Co., Ltd.) was dried at 110 ° C for 30 minutes, and further dried at 150 ° C for 30 minutes. The solid content concentration in the water dispersion of the reverse phase emulsion is 0.2, 0.3 and 0. A 5% emulsion was prepared. Then, the pH immediately after the preparation was measured, and the viscosity was measured using a B-type viscometer (same as above) under the same conditions as in Example 1. The results are shown in Table 5.

[0108]

[Table 5]

Example 3 Each neutralized aqueous solution 2 in which the solid content concentration of the emulsion was 0.5 and 1% (see Table 1)
For 00 parts, bentonite 20 parts and mountain clay 40
Parts were added to each. After that, a stirring disperser (manufactured by Tokushu Kika Kogyo Co., Ltd .; TK Auto Homo Mixer, SL)
Type) and stirred at 6000 rpm for 5 minutes. Then, the viscosity of the suspension immediately after the preparation and after one day (the neutralized aqueous solution to which bentonite and mountain clay were added) was measured using a B-type viscometer (same as above). The results are shown in Table 6.
In addition, the B-type viscometer includes a rotor-NO. 4 at 25 ° C. and the rotation speed of the rotor is 60 min ⁻¹ , 30
min ^-1, 12min ^-1, was measured for each as 6min ^-1.

[0110]

[Table 6]

Example 4 20 parts of bentonite and 40 parts of mountain clay were respectively added to 200 parts of each neutralized aqueous solution having a solid content concentration of 0.1 and 0.2% (see Table 3). added. Then, using the said stirring disperser, it stirred at 6000 rpm for 5 minutes. Then, the viscosity of the suspension immediately after the preparation and after one day (the neutralized aqueous solution to which bentonite and mountain clay were added) was measured under the same conditions as in Example 3 using a B-type viscometer (same as above). The results are shown in Table 7.

[0112]

[Table 7]

[Comparative Example 2] As a comparative example, a reverse phase emulsion (trade name; Invertex AR-25; manufactured by Toagosei Co., Ltd.) was used as an ion so that the solid content concentration of the emulsion was 0.3%. It was added to exchanged water to obtain an emulsion. To 200 parts of this emulsion, 20 parts of bentonite and 40 parts of mountain clay were added. Then, using the said stirring disperser, it stirred at 6000 rpm for 5 minutes. Then, the viscosity of the suspension immediately after preparation and after 1 day (the emulsion in which bentonite and mountain clay were added) was measured under the same conditions as in Example 3 using a B-type viscometer (same as above).
The results are shown in Table 8.

[0114]

[Table 8]

Example 5 A neutralized aqueous solution 180 in which the solid content of the emulsion prepared in Example 2 was 1%
After adding 20 parts of pure water (ion-exchanged water) or artificial seawater (trade name: aquamarine, manufactured by Yashu Pharmaceutical Co., Ltd.) to the parts, pH and viscosity were measured. The viscosity was measured by a B-type viscometer (same as above) using the rotor-NO. 3 was measured under the conditions of 25 ° C. and a rotation speed of 60 min ⁻¹ . Further, the pH and viscosity of 200 parts of a neutralized aqueous solution having a solid content concentration of 1% of the emulsion were measured, and the solid content concentration of the emulsion was 1 with respect to the viscosity of the neutralized aqueous solution to which the pure water or artificial seawater was added. % Of the neutralized aqueous solution to the viscosity (viscosity reduction rate (%)) was determined.

The results are shown in Table 9.

[0117]

[Table 9]

[Comparative Example 3] 180 parts of an emulsion having a solid content concentration of 0.3% of the reverse phase emulsion (trade name; Invertex AR-25; manufactured by Toagosei Co., Ltd.) prepared in Comparative Example 2 was added. After adding 20 parts of pure water (ion-exchanged water) or the artificial seawater, pH and viscosity were measured. The viscosity was measured by a B-type viscometer (same as above) using the rotor-NO. 3 was measured under the conditions of 25 ° C. and a rotation speed of 60 min ⁻¹ . In addition, the solid content of the reverse phase emulsion is 0.3
% Emulsion 200 parts, the pH and viscosity were measured to obtain the emulsion 200 in which the solid content concentration of the reverse phase emulsion was 0.3% of the viscosity of the emulsion to which the pure water or artificial seawater was added. Ratio of part to viscosity (viscosity reduction rate (%))
I asked.

The results are shown in Table 10.

[0120]

[Table 10]

Example 6 7.1 parts of the emulsion obtained in Production Example 2 (2.0 parts as solid content of emulsion)
Part), a 0.5N sodium hydroxide aqueous solution and ion-exchanged water were mixed so as to have a total amount of 200.0 parts and a pH of 7.0 to prepare a neutralized aqueous solution having a solid content concentration of 1%.

With respect to the above neutralized aqueous solution, the viscosity and pH immediately after preparation were measured under the following measuring conditions. The results are shown in Table 11.

(Viscosity measurement) Viscosity measurement was performed using a B-type viscometer (same as above) using a rotor No. 3 is used, the rotation speed is 60 min
⁻¹ , and the measurement temperature was 23.5 ± 1.0 ° C.

(Measurement of pH) The pH was measured at a measuring temperature of 23.5 ± 1.0 ° C. using a pH meter (pH meter F-23, manufactured by Horiba Ltd.). Further, as the calibration solution, a standard buffer solution of 7.0 for pH 7.0 is used.
(Manufactured by Hayashi Pure Chemical Industries, Ltd.), standard buffer solution 9.0 for pH 9.0 (manufactured by Hayashi Pure Chemical Industries, Ltd.), oxalate pH standard solution type 2 for pH 1.68 (Wako Pure Chemical Industries, Ltd.) (Made by corporation)
It was used.

Example 7 6.8 parts of the emulsion obtained in Production Example 3 (2.0% as the solid content of the emulsion)
Part), a 0.5N sodium hydroxide aqueous solution and ion-exchanged water were mixed so as to have a total amount of 200.0 parts and a pH of 7.0 to prepare a neutralized aqueous solution having a solid content concentration of 1%.

Then, the viscosity and pH of the neutralized aqueous solution immediately after preparation were measured under the same measurement conditions as in Example 6. The results obtained are shown in Table 11.

[0127]

[Table 11]

From the above results, it can be seen that the aqueous dispersion of the alkali-soluble polymer has a viscosity similar to that of the reverse phase emulsion. Further, the aqueous dispersion of the alkali-soluble polymer has excellent salt resistance as compared with the conventional reverse phase emulsion. Therefore, the aqueous dispersion of the alkali-soluble polymer according to the present invention can be preferably used as a mud additive.

Further, as can be seen from Example 5 and Comparative Example 3, the viscosity of the mud additive containing the reverse phase emulsion is drastically reduced when salt such as seawater is contained. In the case of the mud additive containing the aqueous dispersion of the alkali-soluble polymer according to the present invention, the degree of decrease in viscosity is less than that of the mud additive containing the reverse phase emulsion. Therefore, the mudifying agent containing the aqueous dispersion of the alkali-soluble polymer according to the present invention can be suitably used even when it contains salt such as seawater.

[0130]

As described above, the mud additive of the present invention is a mud additive used in the shield construction method and the propulsion construction method,
It is a constitution comprising an aqueous dispersion of an alkali-soluble polymer obtained by oil-in-water emulsion polymerization of a monomer composition containing a monomer containing a carboxyl group and / or a salt thereof.

The mud additive of the present invention comprises the above monomer composition,
It is more preferable that the composition further contains a nonionic monomer having a solubility in water at 20 ° C. of 3% by mass or more.

The mud additive of the present invention comprises the above monomer composition,
It is more preferable that the composition further contains another monomer copolymerizable with at least one of the above-mentioned nonionic monomer and a monomer containing the carboxyl group and / or its salt.

The mud additive of the present invention contains 10 to 90% by mass of the monomer containing the carboxyl group and / or a salt thereof, and the nonionic monomer and / or the other monomer. It is more preferable that the total amount of the monomers is in the range of 10 to 90% by mass.

In the mud additive of the present invention, the monomer composition contains a monomer containing a carboxyl group and / or a salt thereof within the range of 30 to 90% by mass. More preferably, the total amount of the ionic monomer and / or the other monomer is contained within the range of 10 to 70 mass%.

The mud additive of the present invention more preferably has a structure in which the alkali-soluble polymer has a weight average molecular weight of 100,000 or more.

It is more preferable that the mud additive of the present invention further contains the above-mentioned mud additive and at least one of an inorganic mineral and a thickener.

In the mud additive of the present invention, the aqueous dispersion of the alkali-soluble polymer is 1% by mass as the solid content of the aqueous dispersion.
It is more preferable that the viscosity of the aqueous solution within the range of pH 6.8 to 7.2 adjusted to 500 mPa · s or more.

According to each of the above constitutions, the dispersion medium of the aqueous dispersion of the alkali-soluble polymer is water. Contamination due to the runoff of organic solvent into the soil does not occur as in. That is, since the excavated soil is less contaminated, the excavated soil can be treated relatively easily. Therefore, for example, the excavated soil can be reused as a resource without being treated as industrial waste. As a result, the cost of processing the excavated soil can be reduced. Further, since the dispersion medium of the alkali-soluble polymer is water, the cost is lower than that of the organic solvent used as the dispersion medium of the conventional reverse phase emulsion. Therefore, the mud additive containing the alkali-soluble polymer has an effect that the total cost can be reduced as compared with the conventional mud additive.

Further, since the above-mentioned mud additive imparts viscosity to the excavated earth and sand to provide fluidity, the excavated earth and sand can be easily transported (conveyed) in the shield construction method and the propulsion construction method. Play together.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Katsuyuki Kono             5-8 Nishiomitabicho, Suita City, Osaka Prefecture             Within Nippon Shokubai F-term (reference) 2D054 DA33 FA03 FA12

Claims (8)

[Claims] 1. A mudifying agent used in a shield method and a propulsion method, which is obtained by oil-in-water emulsion polymerization of a monomer composition containing a monomer containing a carboxyl group and / or a salt thereof. A mudizing agent comprising an aqueous dispersion of an alkali-soluble polymer. 2. The mud additive according to claim 1, wherein the monomer composition further contains a nonionic monomer having a solubility in water at 20 ° C. of 3% by mass or more. 3. The monomer composition comprises another monomer copolymerizable with at least one of the monomer containing the carboxyl group and / or a salt thereof and the nonionic monomer. The mud additive according to claim 1 or 2, further comprising: 4. The monomer composition containing a monomer containing a carboxyl group and / or a salt thereof in an amount of 10 to 90% by mass, wherein the nonionic monomer and 4. The mud additive according to claim 2 or 3, wherein the total amount of the other monomers is within the range of 10 to 90% by mass. 5. The monomer composition contains a monomer containing a carboxyl group and / or a salt thereof within a range of 30 to 90% by mass, and the nonionic monomer and 4. The mud additive according to claim 2, wherein the total amount of the other monomers is 10 to 70% by mass. 6. The mud additive according to claim 1, wherein the alkali-soluble polymer has a weight average molecular weight of 100,000 or more. 7. An aqueous dispersion of the alkali-soluble polymer,
PH 6 adjusted to 1% by mass as the solid content of the aqueous dispersion.
The viscosity of the aqueous solution within the range of 8 to 7.2 is 500 mP.
7. The mud additive according to any one of claims 1 to 6, which is a · s or more. 8. The mudifying agent according to claim 1, further containing at least one of an inorganic mineral and a thickening agent.