JP2005036144A - Excavation stabilizing fluid and excavation technique - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently and inexpensively provide an excavation stabilizing fluid scarcely causing putrefaction, free from toxicity and excellent in viscosity and drainage and further provide an excavation technique using the excavation stabilizing fluid. <P>SOLUTION: The excavation stabilizing fluid comprises a water-soluble polymer (P) having ≥500,000 weight-average molecular weight and obtained by polymerizing a monomer group composed of (A) 20-99 mol% (meth)acrylic acid (salt) and (B) 1-80 mol% specific (meth)acrylate-based monomer as essential components and optionally (C) 0-20 mol% other monomer copolymerizable with components (A) and (B), and water. It is preferable that the weight average molecular weight of the water-soluble polymer (P) is 700,000-4,000,000 and the insoluble content is ≤5 wt.%. The problem to be solved is attained by excavation technique using the excavation stabilizing fluid containing the water-soluble polymer (P). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an excavation stabilizer that can provide good drainage even at low viscosity, and an excavation method using the excavation stabilizer. It also supplies drilling stabilizers that can be expected to have a stable thickening effect even in various soil grounds.

In subway construction, etc., excavation methods such as underground continuous wall method and underground pile method are widely known. The underground continuous wall construction method is a general construction method for building concrete structures underground. This construction method is first started from underground excavation. At this time, in order to prevent the collapse of the wall surface of the excavation hole, excavation is performed while filling the excavation hole with a excavation stabilizing liquid containing clay mineral such as bentonite.
The drilling stabilization liquid used here prevents the wall from softening and the water pressure prevents the wall from collapsing. This is because the added clay mineral is added when the drilling stabilization liquid penetrates the drilling wall. This is thought to be because a water-stopping layer called a mud cake is formed by clogging and accumulating between soil particles.

  In the underground continuous wall construction method, a continuous concrete structure can be formed by excavating while stabilizing the wall surface, and then inserting a reinforcing bar or the like into the premises and driving in the concrete. In this construction method, when the concrete is driven, the excavation stabilizing liquid is replaced with the concrete and recovered.

  In recent years, the content of bentonite tends to be reduced due to the ease of disposal when discarding the used excavation stabilizer, but in this case, the viscosity of the excavation stabilizer decreases to stabilize the wall surface. There is a drawback that the ability (freeness) is reduced. In order to solve this problem, the thickening agent such as carboxymethyl cellulose (CMC) is usually added to the drilling stabilizer. However, the problem is that CMC is easily spoiled, and it is difficult to disperse. There was a problem that it was difficult to obtain a stable solution. Thus, use of various polymers has been proposed in order to solve the problems of CMC.

  There are the following techniques regarding the above-mentioned excavation stabilizer and the thickener for excavation stabilizer. For example, Patent Document 1 proposes the use of a crosslinked polymer and / or an anionic water-soluble polymer having a weight average molecular weight of 1 million or more. Patent Document 2 proposes the use of an acrylamide polymer. Patent Document 3 proposes the use of a sulfonic acid group-containing water-soluble polymer as an acrylamide polymer.

  Patent Document 4 proposes the use of an N-vinylacetamide polymer. Patent Documents 5 and 6 propose the use of an alkoxy group-containing water-soluble polymer. However, although these polymers have the feature that they are not easily spoiled, it is necessary to devise such as requiring a higher amount of addition than CMC.

  In addition, in the case of an acrylamide polymer described in Patent Document 3 or the like, its use is remarkably limited due to toxicity problems of unreacted acrylamide. Patent Document 7 proposes the use of a methyl acrylate copolymer. However, in the case of this polymer, it was necessary to use a relatively expensive polymer having a high copolymerization ratio of methyl acrylate in order to produce a preferable excavation stabilizing liquid. Therefore, it was necessary to devise in terms of cost.

  Furthermore, Patent Document 8 proposes the use of an alkali-soluble emulsion containing a hydrophobic monomer such as ethyl acrylate. Although this polymer has a relatively good evaluation, it is necessary to add an alkaline substance to make it water-soluble at the construction site. It was. Further, as will be described later, the emulsion necessarily contains an emulsifier, and problems such as foaming also occur when it is used as a drilling stabilizer. The water-soluble polymer targeted in the present invention is water-soluble without adding an alkaline substance, and is completely different from the emulsion (alkali-soluble resin) of Patent Document 8.

Japanese Unexamined Patent Publication No. 06-207167

Japanese Unexamined Patent Publication No. 06-025341 Japanese Patent Laid-Open No. 01-310087 International Publication No. W0 00/059964 JP 2000-256661 A JP 2002-194340 A JP 2000-212552 JP JP 2000-212551 A

  Therefore, the problem to be solved by the present invention is to provide an efficient and inexpensive drilling stabilizing liquid that is resistant to spoilage, is not toxic, has low viscosity, and is excellent in drainage. Furthermore, the excavation method using this excavation stability liquid is provided.

  The present inventor has studied from various aspects in order to solve the above-mentioned problem, and the above-mentioned problem is solved by a drilling stabilizing liquid containing a water-soluble copolymer obtained by using a specific monomer component as an essential component. Has been found to be solved all at once, and the present invention has been reached.

Specifically, (meth) acrylic acid (salt) (A) 20 to 99 mol% and (meth) acrylic acid ester monomer (B) represented by the following general formula (1) 1 to 80 mol% Other monomers (C) that can be copolymerized with the monomers represented by the above (A) and (B) (0) to 20 mol% (provided that (A), (B), (C The total amount of) is 100 mol%. A water-soluble polymer (P) having a weight average molecular weight of 500,000 or more obtained by polymerizing a monomer group consisting of) and a drilling stable liquid containing water. As a result, a drilling stabilization liquid that is less susceptible to spoilage, is not toxic, has low viscosity, and is excellent in drainage has been completed.
_{CH 2 = C (R) -COOZ} 1 (O) P Z 2 OX (1)
(Wherein R represents a hydrogen atom or a methyl group, Z ¹ and Z ² each represent an alkylene group having 8 or less carbon atoms, X represents a hydrocarbon group having 4 or less carbon atoms, and P represents an integer of 0 or 1)
More specifically, the drilling stabilizing liquid is characterized in that the water-soluble polymer (P) has a weight average molecular weight of 700,000 to 4,000,000.

  More specifically, the excavation stabilizing liquid is characterized in that the insoluble content of the water-soluble polymer (P) is 5% by weight or less.

  More specifically, the above-mentioned excavation stabilizing liquid is characterized by further containing a viscous mineral.

  More specifically, the present invention relates to an excavation method characterized by excavating the ground while preventing the collapse of the inner wall surface of the excavation hole using the excavation stabilizing liquid described above.

  The excavation stabilizing liquid of the present invention has ideal properties with a funnel viscosity of 25 to 30 seconds and a drainage amount of around 10 ml. In addition, the excavation stabilizing liquid according to the present invention has a feature that it is difficult to rot. Furthermore, since the excavation method according to the present invention uses the above-described excavation stabilizing liquid, it is possible to reliably prevent the collapse of the inner wall surface of the excavation hole, and the waste mud treatment is reduced, which is economically advantageous. It also has. In addition, it is a drilling stable liquid that is non-toxic, low viscosity and excellent in drainage.

  Further, since the excavation stabilizing liquid of the present invention is an excavation stabilizing liquid containing a water-soluble polymer having good resistance to a substance containing a polyvalent metal ion, the water quality used for making the excavation stabilizing liquid is as follows. Water with high salinity such as waste water and seawater can be used. In addition, even if an inorganic substance such as cement is mixed in the drilling stability liquid, there is an effect that the muddy water performance does not change, so that a drilling stability liquid that can be used in a more stable state at various drilling sites is obtained. Can do.

  Details of the embodiment of the present invention will be further described below.

The water-soluble polymer (P) used in the present invention is:
(Meth) acrylic acid (salt) (A) 20 to 99 mol% and (meth) acrylic acid ester monomer (B) 1 to 80 mol% represented by the following general formula (1) are essential. Other monomers copolymerizable with the monomers represented by the above (A) and (B) (C) 0 to 20 mol% (however, the total amount of (A), (B), (C) is It is a water-soluble polymer having a weight average molecular weight of 500,000 or more obtained by polymerizing a monomer group consisting of 100 mol%.
_{CH 2 = C (R) -COOZ} 1 (O) P Z 2 OX (1)
(In the formula, R represents a hydrogen atom or a methyl group, Z ¹ and Z ² each represent an alkylene group having 8 or less carbon atoms, X represents a hydrocarbon group having 4 or less carbon atoms, and P represents an integer of 0 or 1)
(Meth) acrylic acid (salt) (A) in the present invention is (meth) acrylic acid and / or (meth) acrylate, but (meth) acrylic acid is (meth) acrylic acid. Neutralized product obtained by neutralization with monovalent metal, divalent metal, ammonia, organic amine, etc., that is, sodium (meth) acrylate, potassium (meth) acrylate, magnesium (meth) acrylate, (meth) acrylic acid Calcium and ammonium (meth) acrylate are preferred. Among these, sodium (meth) acrylate is preferable. More preferably, it is sodium acrylate. The (meth) acrylic acid monomers may be used alone or in combination of two or more.

  Examples of the (meth) acrylic acid ester monomer (B) represented by the general formula (1) include methoxyethyl (meth) acrylate, methoxyethyloxyethyl (meth) acrylate, methoxypropyl (meth) acrylate, methoxy Suitable are butyl (meth) acrylate, methoxyethyloxybutyl (meth) acrylate, ethoxyethyl (meth) acrylate, ethoxyethyloxyethyl (meth) acrylate, propoxypropyl (meth) acrylate, propoxybutyl (meth) acrylate and the like. Among these, methoxyethyl (meth) acrylate is preferable. More preferred is methoxyethyl acrylate. The (meth) acrylic acid ester monomers may be used alone or in combination of two or more.

  As other copolymerizable monomer (C) other than (meth) acrylic acid (salt) (A) and (meth) acrylic acid ester monomer (B) represented by general formula (1) above Any monomer can be used as long as the resulting water-soluble polymer (P) is water-soluble. Examples of such monomers include α-hydroxyacrylic acid, crotonic acid, and their monovalent metal salts, divalent metal salts, ammonium salts, organic amine salts, and other unsaturated monocarboxylic acid monomers; maleic acid , Fumaric acid, itaconic acid, citraconic acid and their monovalent metal salts, divalent metal salts, ammonium salts, organic amine salts and other unsaturated dicarboxylic acid monomers; vinyl sulfonic acid, allyl sulfonic acid, methallyl sulfone Acid, styrenesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, 3-allyloxy-2-hydroxypropanesulfonic acid, sulfoethyl (meth) acrylate, sulfopropyl (meth) acrylate, 2-hydroxysulfopropyl (meth) acrylate , Sulfoethylmaleimide and their monovalent metal salts, divalent metal salts, ammonium Unsaturated sulfonic acid monomers such as um salts and organic amine salts; (meth) acrylamide methanephosphonic acid, 2- (meth) acrylamide-2-methylpropanephosphonic acid and their monovalent metal salts and divalent metal salts , Unsaturated phosphonic acid monomers such as ammonium salts and organic amine salts; amide monomers such as (meth) acrylamide and t-butyl (meth) acrylamide; 3-methyl-2-buten-1-ol ( Prenol), 3-methyl-3-buten-1-ol (isoprenol), 2-methyl-3-buten-2-ol (isoprene alcohol), 2-hydroxyethyl (meth) acrylate, polyethylene glycol mono (meth) acrylate , Polypropylene glycol mono (meth) acrylate, polyethylene glycol monoisoprenolate , Polypropylene glycol monoisoprenol ether, polyethylene glycol monoallyl ether, polypropylene glycol monoallyl ether, glycerol monoallyl ether, N-methylol (meth) acrylamide, glycerol mono (meth) acrylate, vinyl alcohol and other unsaturated groups Monomer; Alkoxyalkylene glycol mono (meth) acrylate such as methoxypolyethylene glycol mono (meth) acrylate; Cationic monomer such as dimethylaminoethyl (meth) acrylate and dimethylaminopropyl (meth) acrylate; (Meth) acrylonitrile And nitrile monomers such as butyl (meth) acrylate, styrene, 2-methylstyrene, vinyl acetate and the like. These monomers can be used alone or in combination of two or more.

  The total monomer composition used for the polymerization is 100 mol%, and the ratio of the monomer is 20 to 99 mol% of (meth) acrylic acid (salt) (A), and is represented by the general formula (1). The (meth) acrylic acid ester monomer (B) is preferably 1 to 80 mol%, and the other copolymerizable monomer (C) is preferably 0 to 20 mol%. More preferably, (A) is 40 to 95 mol% (B) is 5 to 60 mol% (C) is 0 to 15 mol%. Particularly preferably, (A) is 50 to 90 mol% (B) is 10 to 50 mol% (C) is 0 to 10 mol%.

By using a water-soluble polymer obtained by polymerization at a higher ratio of acrylic acid (salt) (A), a drilling stable liquid having a desired funnel viscosity can be obtained with a smaller addition amount. . However, if the usage ratio of acrylic acid (salt) (A) is too high above the above range (that is, if the usage ratio of (meth) acrylic acid ester monomer (B) is too low than the above range). ) The excavation stabilizing liquid obtained by using the obtained polymer is not preferable because the viscosity of the excavation stabilizing liquid decreases due to contact with a substance containing a large amount of polyvalent metal ions such as cement.
In addition, the amount of drainage increases, which is not preferable. On the other hand, when the polymer (P) having the monomer composition ratio described above is used, water having a high salt concentration such as waste water or seawater can be used as the quality of the water used when creating the excavation stabilization liquid. The utility value is extremely high.

  More specifically, the water-soluble polymer (P) obtained by polymerizing the use ratio of acrylic acid (salt) (A) at the use ratio described above is used as the excavation stabilizing liquid. The drilling stabilizer of the invention has a funnel viscosity (seconds) of 22 to 32 seconds, more preferably 25 to 30 seconds, and a drainage amount of 9 to 15 ml, even with a small addition amount of the polymer. The excavation stabilizing liquid has preferable physical properties. If it is within this range, the excavation stable liquid has good stability and good workability.

  The water-soluble polymer (P) has a weight average molecular weight of 500,000 or more. In the case of a weight average molecular weight of less than 500,000, a preferable drilling stabilizing liquid cannot be obtained. Moreover, it is necessary to increase the amount of addition. The weight average molecular weight is measured by a light scattering method. The upper limit of the weight average molecular weight of the water-soluble polymer (P) is preferably 7 million or less. When the water-soluble polymer (P) having an excessively high weight average molecular weight is used, the added clay mineral may be aggregated, and as a result, a preferable excavation stabilizing liquid may not be obtained. A more preferred weight average molecular weight is 700 to 5,000,000. More preferably, it is 80 to 3 million, and most preferably 1 to 2 million.

  When obtaining a water-soluble polymer (P) having a large weight average molecular weight, the insoluble content may increase during polymerization or during drying.

  The insoluble content of the water-soluble polymer (P) used in the present invention is preferably 5% by weight or less. It is further preferably 1% by weight or less, particularly preferably 0.5% by weight or less. If the insoluble content exceeds 5% by weight, the amount of drainage tends to increase suddenly, which is not preferable. The insoluble matter is measured as follows. If the amount of the insoluble component is large, it becomes difficult to obtain a drilling stabilizing solution with better performance.

(Measurement method of insoluble matter)
In a beaker with a capacity of 500 ml, 500 g of ion-exchanged water was added, and 1.0 g of a sufficiently dried water-soluble polymer (P) was added to the ion-exchanged water while stirring with a magnetic stirrer.
Add. The mixture was then stirred for 2 hours at 25 ° C. using a jar tester (100 r
pm) and then using a 32-mesh filter to remove the water-containing insoluble matter. Then, this insoluble matter is weighed immediately (within 1 minute) so as not to dry, and the insoluble matter is calculated based on the following formula.
Insoluble matter (mass%) = {mass of insoluble matter (g) / 500 (g)} × 100
The filtration and weighing are also performed at 25 ° C. and a relative humidity of 60%.

  The water-soluble polymer (P) of the present invention can be produced by various polymerization methods such as a reverse layer suspension polymerization method and a solution polymerization method, but is not particularly limited, but is preferably a solution polymerization method, and more preferably an aqueous solution. A method of polymerizing by a stationary polymerization method is preferable because a water-soluble polymer having a small amount of insoluble matter and a high molecular weight can be produced. As a polymerization mode, a cast polymerization method or a belt polymerization method can be employed. The monomer concentration during polymerization is preferably 30 to 90% by weight. More preferably, it is 35 to 70% by weight. Particularly preferred is 40 to 60% by weight.

  By adjusting the monomer concentration, the weight average molecular weight of the obtained water-soluble polymer (P) can be further increased, and the amount of the remaining monomer can also be reduced. Moreover, the insoluble content of the obtained water-soluble polymer (P) can also be reduced, and the water-soluble polymer (P) having the optimum physical properties to be added to the excavation stabilizing liquid of the present invention can be produced.

  In addition, when an emulsion polymer produced by an emulsion polymerization method is used as the excavation stabilization liquid, there is a problem that the emulsifier used during the emulsion polymerization is liberated and the excavation stabilization liquid is foamed. Foaming reduces the specific gravity of the excavation stabilizing liquid, and the pressure balance with the excavation groove wall is not achieved, and the wall is liable to collapse, and workability such as idling of the circulation pump is reduced. Although an antifoaming agent can be blended, it is necessary to use a considerable amount of the antifoaming agent in order to reduce the foaming, which causes a problem in terms of cost or workability. Therefore, the water-soluble polymer of the present invention is preferably in the form produced by the above aqueous solution polymerization method.

  As the polymerization method, either thermal polymerization or photopolymerization can be used. However, the photopolymerization method is more preferable because a polymer having a small insoluble content and a large weight average molecular weight is easily obtained.

Therefore, as the water-soluble polymer (P) in the present invention, the total monomer composition used for the polymerization is 100 mol%, the (meth) acrylic acid (salt) (A) is 20 to 99 mol%, the above general Monomer in which the (meth) acrylic acid ester monomer (B) represented by the formula (1) is adjusted to 1 to 80 mol% and the other copolymerizable monomer (C) is adjusted to 0 to 20 mol%. A polymer obtained by photopolymerizing the body composition is preferred. More preferably, the monomer used is (A) 40 to 95 mol%, (B) 5 to 60 mol%, and (C) 0 to 15 mol%. Particularly preferably, (A) is 50 to 90 mol% (B) is 10 to 50 mol% (C) is 0 to 10 mol%. In addition, a water-soluble polymer obtained by photopolymerization using a monomer concentration of 30 to 90% by weight, more preferably 35 to 70% by weight, particularly preferably 40 to 60% by weight as a monomer concentration during polymerization ( P) is a preferred embodiment.
Specific examples of the polymerization initiator in the case of thermal polymerization include hydrogen peroxide; persulfates such as sodium persulfate, potassium persulfate, and ammonium persulfate; 2,2′-azobis- (2- Water-soluble radical polymerization initiators such as azo compounds such as amidinopropane) dihydrochloride and 2,2'-azobis- [2- (2-imidazolin) -2-yl] propane] dihydrochloride. These thermal polymerization initiators may be used alone or in combination of two or more. Of the thermal polymerization initiators exemplified above, azo compounds are particularly preferred.

The amount of the thermal polymerization initiator used is preferably in the range of 0.0001 g to 0.05 g with respect to 1 mol of the monomer component. The polymerization initiation temperature for the thermal polymerization is preferably 15 ° C to 50 ° C. The polymerization is preferably controlled so that the maximum temperature of the reaction solution during polymerization is 150 ° C. or lower, preferably 120 ° C., more preferably 110 ° C. or lower. Specific examples of the polymerization initiator in the case of photopolymerization include 2,2′-azobis (2-amidinopropane), 2,2′-azobis (N, N′-dimethyleneisobutylamidine), 2 , 2'-azobis [2- (5-methyl-2-imidazolin-2-yl) propane], 1,1'-azobis (1-amidino-1-cyclopropylethane), 2,2'-azobis (2 -Amidino-4-methylpentane), 2,2'-azobis (2-N-phenylaminoamidinopropane), 2,2'-azobis (1-imino-1-ethylamino-2-methylpropane), 2, 2'-azobis (1-allylamino-1-imino-2-methylbutane), 2,2'-azobis (2-N-cyclohexylamidinopropane), 2,2'-azobis (2-N-benzylamidino) Lopan) and its hydrochloric acid, sulfuric acid, acetate, etc., 4,4′-azobis (4-cyanovaleric acid) and its alkali metal salt, ammonium salt, amine salt, 2- (carbamoylazo) isobutyronitrile, 2'-azobis (isobutyramide), 2,2'-azobis [2-methyl-N- (2-hydroxyethyl) propionamide], 2,2'-azobis [2-methyl-N- (1,1 ' -Bis (hydroxymethyl) ethyl) propionamide], 2,2′-azobis [2-methyl-N-1,1′-bis (hydroxyethyl) propionamide] and the like, 2,2 -Dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 2-hydroxy-2-methyl-1-phenyl-propane-1- Eutectic mixture of 1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184) and benzophenone, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propane- 1-one, 2-methyl-1 [4- (methylthio) phenyl] -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1 (Irgacure 369) and 2,2-dimethoxy-1,2-diphenylethane-1-one (Irgacure 651) 3: 7 mixture, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, bis (2,6-dimethoate) 1: 3 mixture of xylbenzoyl) -2,4,4-trimethyl-pentylphosphine oxide (CGI403) and 2-hydroxy-2-methyl-1-phenyl-propan-1-one (Darocur 1173), bis A 1: 3 mixture of (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine oxide (CGI403) and 1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184), bis (2, 6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine oxide (CGI 403) and 1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184), 2,4,6-trimethyl Benzoyl-diphenyl-phosphine oxide and 2- - Dorokishi-2-methyl-1 with (Darocure 1173): 1 liquid mixture, bis (eta ^{5-2,4-cyclopentadiene-1-yl)} - bis (2,6 -Difluoro-3- (1H-pyrrol-1-yl) -phenyl) titanium, oligo [2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propanone], 2,4,6 -Eutectic mixture of trimethylbenzophenone and 4-methylbenzophenone, liquid mixture of 4-methylbenzophenone and benzophenone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide and oligo [2-hydroxy-2-methyl-1- A liquid mixture of [4- (1-methylvinyl) phenyl] propanone] and a methylbenzophenone derivative, 1- [4- ( 4-benzoylphenylsulfanyl) phenyl] -2-methyl-2- (4-methylphenylsulfanyl) propan-1-one, benzyldimethyl ketal, 2-hydroxy-2-methyl-1-phenyl-1-propanone, α- Hydroxycyclohexyl-phenyl ketone, ethyl 4-dimethylaminobenzoate, acrylated amine synergist, benzoin (iso- and n-) butyl ester, acrylic sulfonium (mono, di) hexafluorophosphate, 2-isopropylthioxanthone, 4- Benzoyl-4'-methyldiphenyl sulfide, 2-butoxyethyl 4- (dimethylamino) benzoate, ethyl 4- (dimethylamino) benzoate, benzoin, benzoin alkyl ether, benzoin hydroxyalkyl ether Le, diacetyl and its derivatives, anthraquinone and its derivatives, diphenyl disulfide and its derivatives, benzophenone and its derivatives, benzyl and its derivatives. Among these, an azo photopolymerization initiator is preferably used, and a water-soluble azo photopolymerization initiator such as 2,2′-azobis-2-amidinopropane dihydrochloride is preferably used.

The amount of the photopolymerization initiator used is preferably 0.0001 g or more and more preferably 1 g or less with respect to 1 mol of the monomer component used for polymerization. Thereby, the weight average molecular weight and polymerization rate of water-soluble polymer (P) can be made high enough. More preferably, it is 0.001 g or more and 0.5 g or less. The polymerization initiation temperature for photopolymerization is preferably 0 ° C to 30 ° C. The polymerization is preferably controlled so that the maximum temperature of the reaction solution during polymerization is 150 ° C. or lower, preferably 120 ° C., more preferably 110 ° C. or lower.
In the photopolymerization step, it is preferable to irradiate the reaction solution with near ultraviolet rays. As a device for irradiating near ultraviolet rays, a high pressure mercury lamp, a low pressure mercury lamp, a metal halide lamp, a fluorescent chemical lamp, and a fluorescent blue lamp are suitable. Further, the wavelength region of near ultraviolet rays is preferably 300 nm or more, and preferably 500 nm or less. By irradiating the reaction liquid with ultraviolet rays having a wavelength in this range, photopolymerization starts and the polymerization reaction proceeds at an appropriate rate. In the present invention, the photopolymerization step is preferably performed by irradiating near ultraviolet rays with an intensity of 0.1 to 100 W / m ² . Thereby, an insoluble part can be decreased more.

  In order to obtain the water-soluble polymer (P) of the present invention, it is preferable to use a chain transfer agent together with the above polymerization initiator. By using an appropriate amount of chain transfer agent, a polymer having a large weight average molecular weight and a small insoluble content can be easily obtained. Examples of the chain transfer agent include sulfur-containing compounds such as thioglycolic acid, thioacetic acid and mercaptoethanol; phosphorous compounds such as phosphorous acid and sodium phosphite; hypophosphorous compounds such as hypophosphorous acid and sodium hypophosphite Alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol and n-butyl alcohol are preferred.

  Among these, hypophosphorous acid compounds are preferable. More preferred is sodium hypophosphite. The amount of the chain transfer agent used may be set as appropriate depending on the polymerization concentration, the combination with the photopolymerization initiator, etc., but is preferably 0.0001 g or more with respect to 1 mol of the monomer component used for the polymerization. Moreover, 0.2 g or less is preferable. Further, it is more preferably 0.001 g or more and 0.15 g or less, particularly preferably 0.005 g or more and 0.10 g or less.

[Clay mineral]
In the excavation stabilizer according to the present invention, the clay mineral imparts basic viscosity characteristics and drainage to the excavation stabilizer. Examples of clay minerals include sepiolite, attapulgite, entry guide, bentonite, kaolin clay, montmorillonite, ectolite, saponite, beidellite, zeolite, palygorskalite, mica, etc. Is done. Among these, at least one selected from sepiolite, attapulgite, entry guide, bentonite, and kaolin clay is preferable because of high drainage.

[Drilling stabilizer]
The excavation stabilizing liquid according to the present invention is basically a liquid containing the above-mentioned water-soluble copolymer (P) and water, but at any point just before construction, the above-mentioned clay mineral or necessary Depending on the case, it may be a liquid further containing other additives. There are no particular limitations on the mutual proportions of the above components constituting the drilling stabilization liquid, but the blending ratio of the copolymer (P) is preferably 0.01 to 20 parts by weight, more preferably 0.01 to 20 parts by weight, in 100 parts by weight of the drilling stabilization liquid. Is 0.05 to 10 parts by weight. If the blending ratio of the copolymer (P) is less than 0.01 parts by weight, the drainage may be lowered. On the other hand, when the blending ratio of the copolymer (P) is more than 20 parts by weight, the funnel viscosity of the excavation stabilizing liquid becomes too high and it may be difficult to handle. The blending ratio of the clay mineral is preferably 20 parts by weight or less, more preferably 0.5 to 10 parts by weight, in 100 parts by weight of the excavation stabilizing liquid. When the blending ratio of the clay mineral exceeds 20 parts by weight, the funnel viscosity may be too high.

  In addition to the above components, the excavation stabilizing liquid is, for example, an alkaline substance such as sodium hydroxide, potassium hydroxide, sodium carbonate, ammonia (water), amines, etc .; silicone-based antifoaming agent, prolunic antifoaming agent, mineral-based An antifoaming agent such as an antifoaming agent; a dispersing agent such as a polyacrylic acid-based dispersing agent; an additive such as a water-soluble polymer such as CMC, polyacrylamide, or polyvinyl alcohol may be blended. The additive can be blended within a range that does not significantly reduce the drainage of the excavation stabilizing liquid.

[Drilling method]
The excavation method for excavating the ground while preventing the collapse of the inner wall surface of the excavation hole using the excavation stabilizing liquid of the present invention is performed by using an excavator such as a drill, a BW excavator, a bucket-type hydrophrase, or an electromill. When the excavation stabilizing liquid (which may contain clay minerals) of the present invention is filled in the excavation hole while forming an excavation hole such as a tunnel, clay such as bentonite is used when the excavation stabilization liquid penetrates into the inner wall surface of the excavation hole. When the mineral is clogged and deposited in the gaps between the soil particles, a mud wall layer called mud cake is formed which is difficult to pass water.

  This mud wall layer has high water-stopping properties, reinforces the excavation wall surface, and prevents the collapse of the inner wall surface of the excavation hole due to the hydraulic pressure of the excavation stabilizing liquid. As described above, after excavating while stabilizing the wall surface, a continuous concrete structure is formed by inserting a reinforcing bar or the like into the premises and driving in the concrete. Here, when the concrete is driven in, the excavation stabilizing liquid is replaced with concrete, and the excavation stabilizing liquid is recovered. This excavation method can be used for any method that uses excavation stabilization liquid, such as the construction method that does not replace the stabilizing liquid such as shield method with concrete, the excavation method that replaces the excavation stability liquid such as continuous underground wall method or underground pile method with concrete, etc. Can be widely used in construction methods.

  It can also be adapted to vertical tunnel construction method (standing pile construction method) with deep vertical piles, water added to the excavated soil at the bottom of the vertical piles to fluidize, stabilize the mud, and discharge continuously with a pump. It is.

Examples of the present invention and comparative examples are shown below, but the present invention is not limited to the following examples. Hereinafter, “%” represents “% by weight”, and “part” represents “part by weight”.

In addition, the measuring method of the weight average molecular weight of the polymer in this invention is measured on condition of the following using a dynamic light scattering photometer.
Apparatus: Dynamic light scattering photometer (trade name: DSL-700, manufactured by Otsuka Electronics Co., Ltd.)
Solvent: 0.16 M / L NaCl aqueous solution Sample concentration: 0.05-2 mg / ml
Sample pH: 10 (at 25 ° C)
Measurement temperature: 25 ° C
<Example 1>
In a beaker having a capacity of 500 ml, 17.08 g of acrylic acid, 27.66 g of a 37% aqueous solution of sodium acrylate, 31.46 g of methoxyethyl acrylate and 71.38 g of ion-exchanged water were collected and mixed. The beaker containing the mixed solution was covered with Saran wrap, and dissolved oxygen in the mixed solution was removed by bubbling nitrogen while cooling. Next, while stirring, 1.21 g of a sodium hypophosphite 3.0% aqueous solution as a chain transfer agent (0.06 g with respect to 1 mol of the total monomer composition) and Darocur (DC) 1173 as a photopolymerization initiator (Ciba Subsi) 1.21 g of 1% acrylic acid solution of Yarity Chemicals, chemical name; 2-hydroxy-2-methyl-1-phenyl-propan-1-one) (0.020 g relative to 1 mol of the total monomer composition) Was added to prepare a reaction solution. The monomer composition in the reaction solution was 42 mol% acrylic acid, 18 mol% sodium acrylate, and 40 mol% methoxyethyl acrylate.

The total monomer concentration in the reaction solution was 40%, and the solution temperature was adjusted to 7 ° C. The reaction solution was irradiated for 15 minutes at a light intensity of 22 W / m ² using near ultraviolet rays (black light mercury lamp manufactured by Toshiba Corporation, model name H400BL-L) having a wavelength range of 300 to 450 nm. Polymerization started immediately after the start of irradiation. Irradiation was continued for 15 minutes to complete the polymerization. After cooling, the resulting gel polymer was cut with scissors and dried at 120 ° C. for 5 hours using a vacuum dryer. Next, the mixture was pulverized using a table-type pulverizer, and the water-soluble polymer having a neutralization degree of 30 mol% with acrylic acid / sodium acrylate / methoxyethyl acrylate = 42/18/40 molar ratio according to the present invention (1 ) The water-soluble polymer (1) had a weight average molecular weight of 1.45 million and an insoluble content of 0.03%.

  Next, a drilling stabilization liquid using the water-soluble polymer (1) was prepared as follows and its performance was evaluated. In a stainless steel cup, 1.2 parts of the water-soluble polymer (1) was measured in terms of solid content, and water was added to make a total amount of 600 parts, followed by dissolution. In this way, 600 parts of a 0.2% aqueous solution of the water-soluble polymer (1) was obtained. Furthermore, 0.6 parts of Nopco 8034L (manufactured by San Nopco Co., Ltd.) and 18 parts of bentonite (Kunigel VI: made by Kunimine Kogyo Co., Ltd.), which are silicone-based antifoaming agents, were added, and the rotational speed was measured using a Hamilton Beach mixer. The mixture was stirred at 1200 rpm for 10 minutes. After leaving for 24 hours, the mixture was stirred again at a rotational speed of 1200 rpm for 15 minutes using a Hamilton Beach mixer to obtain a drilling stable liquid (1) of the present invention. The funnel viscosity and the amount of drainage were measured by a method according to the American Petroleum Institute (API) test method shown below. As a result, the funnel viscosity was 27.22 seconds and the amount of drainage was 9.5 ml.

(Measurement method of funnel viscosity)
500 ml of the above-mentioned excavation stabilizing liquid is taken in a funnel type funnel viscometer, and the time until the whole amount flows out is measured.

(Measurement method of drainage)
290 ml of the stabilizing solution was placed in the cylinder of the drainage measuring device, and Toyo filter paper No. 9 having a diameter of 9 cm was used. Set 4 and set the lid with drain. The cylinder was fixed at a predetermined position, a graduated cylinder was set, a pressure (3 kg / cm ² ) was applied to the cylinder using a nitrogen cylinder, and the amount of water (ml) flowing out for 30 minutes was measured with the graduated cylinder.

<Example 2>
In a 500 ml beaker, 35.71 g of acrylic acid, 56.28 g of 37% aqueous solution of sodium acrylate, 1.96 g of methoxyethyl acrylate and 53.03 g of ion-exchanged water were collected and mixed. The beaker containing the mixed solution was covered with Saran wrap, and dissolved oxygen in the mixed solution was removed by bubbling nitrogen while cooling. Next, 1.51 g of a sodium hypophosphite 3.0% aqueous solution as a chain transfer agent (0.06 g with respect to 1 mol of the total monomer composition) and Darocur (DC) 1173 (Ciba Subeshi) as a photopolymerization initiator while stirring. 1.51 g of 1% acrylic acid solution of Yarity Chemicals, chemical name; 2-hydroxy-2-methyl-1-phenyl-propan-1-one) (0.020 g relative to 1 mol of the total monomer composition) Was added to prepare a reaction solution. The monomer composition in the reaction solution was 68.6 mol% acrylic acid, 29.4 mol% sodium acrylate, and 2.0 mol% methoxyethyl acrylate.

The total monomer concentration in the reaction solution was 40%, and the solution temperature was adjusted to 7 ° C. The reaction solution was irradiated for 15 minutes at a light intensity of 22 W / m ² using near ultraviolet rays (black light mercury lamp manufactured by Toshiba Corporation, model name H400BL-L) having a wavelength range of 300 to 450 nm. Polymerization started immediately after the start of irradiation. Irradiation was continued for 15 minutes to complete the polymerization. After cooling, the resulting gel polymer was cut with scissors and dried at 120 ° C. for 5 hours using a vacuum dryer. Next, the mixture was pulverized using a desktop pulverizer, and the water-soluble polymer (2) having a molar ratio of acrylic acid / sodium acrylate / methoxyethyl acrylate = 68.6 / 29.4 / 2.0 molar ratio according to the present invention was 30 mol%. ) The water-soluble polymer (2) had a weight average molecular weight of 1.63 million and an insoluble content of 0.06%. Excavation stability liquid was prepared in the same manner as in Example 1 except that the water-soluble polymer (2) was used, and the evaluation of the excavation stability liquid was measured in the same manner as in Example 1. As a result, the funnel viscosity was 31.36 seconds and the drainage amount was 11.4 ml.

<Example 3>
In a beaker having a capacity of 500 ml, 5.43 g of acrylic acid, 9.75 g of a 37% aqueous solution of sodium acrylate, 49.94 g of methoxyethyl acrylate, and 82.84 g of ion-exchanged water were collected and mixed. The beaker containing the mixed solution was covered with Saran wrap, and dissolved oxygen in the mixed solution was removed by bubbling nitrogen while cooling. Next, 1.02 g of a sodium hypophosphite 3.0% aqueous solution as a chain transfer agent (0.06 g with respect to 1 mol of the total monomer composition) and Darocur (DC) 1173 (Ciba Subeshi) as a photopolymerization initiator while stirring. 1.02 g of 1% acrylic acid solution of Yarity Chemicals, chemical name; 2-hydroxy-2-methyl-1-phenyl-propan-1-one) (0.020 g relative to 1 mol of the total monomer composition) Was added to prepare a reaction solution. The monomer composition in the reaction solution was 17.5 mol% acrylic acid, 7.5 mol% sodium acrylate, and 75.0 mol% methoxyethyl acrylate.

The total monomer concentration in the reaction solution was 40%, and the solution temperature was adjusted to 7 ° C. The reaction solution was irradiated for 15 minutes at a light intensity of 22 W / m ² using near ultraviolet rays (black light mercury lamp manufactured by Toshiba Corporation, model name H400BL-L) having a wavelength range of 300 to 450 nm. Polymerization started immediately after the start of irradiation. Irradiation was continued for 15 minutes to complete the polymerization. After cooling, the resulting gel polymer was cut with scissors and dried at 120 ° C. for 5 hours using a vacuum dryer. Next, the mixture was pulverized using a table-type pulverizer, and a water-soluble polymer having a neutralization degree of 30 mol% with an acrylic acid / sodium acrylate / methoxyethyl acrylate = 17.5 / 7.5 / 75 molar ratio according to the present invention (3 ) The water-soluble polymer (3) had a weight average molecular weight of 1.54 million and an insoluble content of 0.21%. Met. Excavation stabilization liquid was prepared in the same manner as in Example 1 except that the water-soluble polymer (3) was used, and the evaluation of the excavation stabilization liquid was measured in the same manner as in Example 1. As a result, the funnel viscosity was 24.26 seconds and the amount of drainage was 10.6 ml.

<Example 4>
In a beaker having a capacity of 500 ml, 12.56 g of acrylic acid, 27.29 g of a 37% aqueous solution of sodium acrylate, 5.13 g of methacrylic acid, 31.02 g of methoxyethyl acrylate and 71.62 g of ion-exchanged water were collected and mixed. The beaker containing the mixed solution was covered with Saran wrap, and dissolved oxygen in the mixed solution was removed by bubbling nitrogen while cooling. Next, 1.19 g of a sodium hypophosphite 3.0% aqueous solution (0.06 g with respect to 1 mol of the total monomer composition) as a chain transfer agent and Darocur (DC) 1173 (Ciba Subeshi) as a photopolymerization initiator while stirring. 1.19 g of 1% acrylic acid solution of Yarity Chemicals, chemical name; 2-hydroxy-2-methyl-1-phenyl-propan-1-one) (0.020 g relative to 1 mol of the total monomer composition) Was added to prepare a reaction solution. The monomer composition in the reaction solution was 32.0 mol% acrylic acid, 18.0 mol% sodium acrylate, 10.0 mol% methacrylic acid, and 40.0 mol% methoxyethyl acrylate.

The total monomer concentration in the reaction solution was 40%, and the solution temperature was adjusted to 7 ° C. The reaction solution was irradiated for 60 minutes at a light intensity of 22 W / m ² using near ultraviolet light (black light mercury lamp manufactured by Toshiba Corporation, model name H400BL-L) having a wavelength range of 300 to 450 nm. Polymerization started about 15 minutes after the start of irradiation. Irradiation was continued for 60 minutes to complete the polymerization. After cooling, the resulting gel polymer was cut with scissors and dried at 120 ° C. for 5 hours using a vacuum dryer. Next, pulverization is performed using a table-type pulverizer, and the aqueous solution having an acrylic acid / sodium acrylate / methacrylic acid / methoxyethyl acrylate = 32.0 / 180 / 10.0 / 40.0 molar ratio and a neutralization degree of 30 mol% according to the present invention. Sex polymer (4) was obtained. The water-soluble polymer (4) had a weight average molecular weight of 1.66 million and an insoluble content of 1.21%. there were. Excavation stabilization liquid was prepared in the same manner as in Example 1 except that the water-soluble polymer (4) was used, and the evaluation of the excavation stability liquid was measured in the same manner as in Example 1. As a result, the funnel viscosity was 28.34 seconds and the drainage amount was 10.2 ml.

<Example 5>
In a beaker having a capacity of 500 ml, 17.08 g of acrylic acid, 27.66 g of a 37% aqueous solution of sodium acrylate, 31.46 g of methoxyethyl acrylate, and 70.88 g of ion-exchanged water were collected and mixed. The beaker containing the mixed solution was covered with Saran wrap, and dissolved oxygen in the mixed solution was removed by bubbling nitrogen while cooling. Next, while stirring, 1.71 g of a sodium hypophosphite 6.0% aqueous solution as a chain transfer agent (0.17 g with respect to 1 mol of the total monomer composition) and Darocur (DC) 1173 as a photopolymerization initiator (Ciba Subsi) 1.21 g of 1% acrylic acid solution of 2-hydroxy-2-methyl-1-phenyl-propan-1-one (manufactured by Yarity Chemicals; chemical name; 0.020 g relative to 1 mol of the total monomer composition) Was added to prepare a reaction solution. The monomer composition in the reaction solution was 42.0 mol% acrylic acid, 18.0 mol% sodium acrylate, and 40.0 mol% methoxyethyl acrylate.

The total monomer concentration in the reaction solution was 40%, and the solution temperature was adjusted to 7 ° C. The reaction solution was irradiated for 15 minutes at a light intensity of 22 W / m ² using near ultraviolet rays (black light mercury lamp manufactured by Toshiba Corporation, model name H400BL-L) having a wavelength range of 300 to 450 nm. Polymerization started immediately after the start of irradiation. Irradiation was continued for 15 minutes to complete the polymerization. After cooling, the resulting gel polymer was cut with scissors and dried at 120 ° C. for 5 hours using a vacuum dryer. Next, the mixture was pulverized using a table-type pulverizer, and a water-soluble polymer having a neutralization degree of 30 mol% with an acrylic acid / sodium acrylate / methoxyethyl acrylate = 42.0 / 18.0 / 40.0 molar ratio according to the present invention (5 ) The water-soluble polymer (5) had a weight average molecular weight of 550,000 and an insoluble content of 0.02%. Met. Excavation stabilization liquid was prepared in the same manner as in Example 1 except that the water-soluble polymer (5) was used, and the evaluation of the excavation stabilization liquid was measured in the same manner as in Example 1. As a result, the funnel viscosity was 22.37 seconds and the drainage amount was 12.3 ml.

<Example 6>
In a 500 ml beaker, 17.69 g of acrylic acid, 29.05 g of 37% aqueous solution of sodium acrylate,
Acrylamide (5.41 g), methoxyethyl acrylate (39.63 g) and ion-exchanged water (55.56 g) were collected and mixed. The beaker containing the mixed solution was covered with Saran wrap, and dissolved oxygen in the mixed solution was removed by bubbling nitrogen while cooling. Next, 1.14 g of a sodium hypophosphite 2.0% aqueous solution as a chain transfer agent (0.03 g with respect to 1 mol of the total monomer composition) and Darocur (DC) 1173 (Ciba Subeshi) as a photopolymerization initiator while stirring. 1.52 g of 1% acrylic acid solution of Yarity Chemicals, Chemical Name; 2-hydroxy-2-methyl-1-phenyl-propan-1-one) (0.020 g relative to 1 mol of the total monomer composition) Was added to prepare a reaction solution. The monomer composition in the reaction solution is 35.0 mol% acrylic acid, 15.0 mol% sodium acrylate,
It was 10.0 mol% of acrylamide and 40.0 mol% of methoxyethyl acrylate.

The total monomer concentration in the reaction solution was 50%, and the solution temperature was adjusted to 7 ° C. The reaction solution was irradiated for 15 minutes at a light intensity of 22 W / m ² using near ultraviolet rays (black light mercury lamp manufactured by Toshiba Corporation, model name H400BL-L) having a wavelength range of 300 to 450 nm. Polymerization started immediately after the start of irradiation. Irradiation was continued for 15 minutes to complete the polymerization. After cooling, the resulting gel polymer was cut with scissors and dried at 120 ° C. for 5 hours using a vacuum dryer. Next, the mixture is pulverized using a table-type pulverizer, and water-soluble with a neutralization degree of 30 mol% at an acrylic acid / sodium acrylate / acrylamide / methoxyethyl acrylate = 35.0 / 15.0 / 10.0 / 40.0 molar ratio according to the present invention. A polymer (6) was obtained. The water-soluble polymer (6) had a weight average molecular weight of 3.1 million and an insoluble content of 3.70%. Excavation stabilization liquid was prepared in the same manner as in Example 1 except that the water-soluble polymer (6) was used, and the evaluation of the excavation stabilization liquid was measured in the same manner as in Example 1. As a result, the funnel viscosity was 33.46 seconds and the drainage amount was 13.6 ml.

<Example 7>
In a 500 ml beaker, 30.55 g of acrylic acid, 48.34 g of 37% aqueous solution of sodium acrylate, 10.15 g of ethoxyethyl acrylate, and 58.14 g of ion-exchanged water were collected and mixed. The beaker containing the mixed solution was covered with Saran wrap, and dissolved oxygen in the mixed solution was removed by bubbling nitrogen while cooling. Then, while stirring, 1.41 g of a sodium hypophosphite 3.0% aqueous solution as a chain transfer agent (0.06 g with respect to 1 mol of the total monomer composition) and Darocur (DC) 1173 as a photopolymerization initiator (Ciba Subsi) 1.41 g of 1% acrylic acid solution of Yarity Chemicals, chemical name; 2-hydroxy-2-methyl-1-phenyl-propan-1-one) (0.020 g relative to 1 mol of the total monomer composition) Was added to prepare a reaction solution. The monomer composition in the reaction solution was 63.0 mol% acrylic acid, 27.0 mol% sodium acrylate, and 10.0 mol% ethoxyethyl acrylate.

The total monomer concentration in the reaction solution was 40%, and the solution temperature was adjusted to 7 ° C. The reaction solution was irradiated for 15 minutes at a light intensity of 22 W / m ² using near ultraviolet rays (black light mercury lamp manufactured by Toshiba Corporation, model name H400BL-L) having a wavelength range of 300 to 450 nm. Polymerization started immediately after the start of irradiation. Irradiation was continued for 15 minutes to complete the polymerization. After cooling, the resulting gel polymer was cut with scissors and dried at 120 ° C. for 5 hours using a vacuum dryer. Next, the mixture was pulverized using a table-type pulverizer, and the water-soluble polymer (7) having a molar ratio of acrylic acid / sodium acrylate / ethoxyethyl acrylate = 63.0 / 27.0 / 10.0 and a neutralization degree of 30 mol% according to the present invention (7 ) The water-soluble polymer (7) had a weight average molecular weight of 1.26 million and an insoluble content of 0.36%. Met. Excavation stabilization liquid was prepared in the same manner as in Example 1 except that the water-soluble polymer (7) was used, and the evaluation of the excavation stabilization liquid was measured in the same manner as in Example 1. As a result, the funnel viscosity was 27.96 seconds and the drainage amount was 9.9 ml.

<Example 8>
In a beaker having a capacity of 500 ml, 123.0 g of a 37% aqueous solution of sodium acrylate, 6.99 g of methoxyethyl acrylate, and 17.69 g of ion-exchanged water were collected and mixed. The beaker containing the mixed solution was covered with Saran wrap, and dissolved oxygen in the mixed solution was removed by bubbling nitrogen while cooling. Next, while stirring, 1.25 g of a sodium hypophosphite 3.0% aqueous solution as a chain transfer agent (0.07 g with respect to 1 mol of the total monomer composition) and 2,2′-azobis-2-2 as a photopolymerization initiator Amidinopropane dihydrochloride (manufactured by Wako Pure Chemical Industries, Ltd., trade name V-50) 1.07 g of 1% aqueous solution (0.020 g relative to 1 mol of the total monomer composition) was added to prepare a reaction solution. The monomer composition in the reaction solution was 90.0 mol% sodium acrylate and 10.0 mol% methoxyethyl acrylate.

The total monomer concentration in the reaction solution was 35%, and the solution temperature was adjusted to 7 ° C. The reaction solution was irradiated for 15 minutes at a light intensity of 22 W / m ² using near ultraviolet rays (black light mercury lamp manufactured by Toshiba Corporation, model name H400BL-L) having a wavelength range of 300 to 450 nm. Polymerization started immediately after the start of irradiation. Irradiation was continued for 15 minutes to complete the polymerization. After cooling, the resulting gel polymer was cut with scissors and dried at 120 ° C. for 5 hours using a vacuum dryer. Subsequently, it grind | pulverized using the table-type grinder, and obtained the water-soluble polymer (8) of 100 mol% of neutralization degree by the sodium acrylate / methoxyethyl acrylate = 90.0 / 10.0 molar ratio which concerns on this invention. The water-soluble polymer (8) had a weight average molecular weight of 920,000 and an insoluble content of 0.16%. Met. Excavation stabilization liquid was prepared in the same manner as in Example 1 except that the water-soluble polymer (8) was used, and the evaluation of the excavation stabilization liquid was measured in the same manner as in Example 1. As a result, the funnel viscosity was 24.11 seconds and the drainage amount was 11.7 ml.

<Example 9>
In a beaker having a capacity of 500 ml, 17.08 g of acrylic acid, 27.66 g of a 37% aqueous solution of sodium acrylate, 31.46 g of methoxyethyl acrylate and 71.8 g of ion-exchanged water were collected and mixed. The beaker containing the mixed solution was covered with Saran wrap, and dissolved oxygen in the mixed solution was removed by bubbling nitrogen while cooling. Next, while stirring, 0.79 g of a sodium hypophosphite 1.0% aqueous solution as a chain transfer agent (0.013 g relative to 1 mol of the total monomer composition) and Darocur (DC) 1173 as a photopolymerization initiator (Ciba Subsi) 1.21 g of 1% acrylic acid solution of Yarity Chemicals, chemical name; 2-hydroxy-2-methyl-1-phenyl-propan-1-one) (0.020 g relative to 1 mol of the total monomer composition) Was added to prepare a reaction solution. The monomer composition in the reaction solution was 42.0 mol% acrylic acid, 18.0 mol% sodium acrylate, and 40.0 mol% methoxyethyl acrylate.

The total monomer concentration in the reaction solution was 40%, and the solution temperature was adjusted to 7 ° C. The reaction solution was irradiated for 15 minutes at a light intensity of 22 W / m ² using near ultraviolet rays (black light mercury lamp manufactured by Toshiba Corporation, model name H400BL-L) having a wavelength range of 300 to 450 nm. Polymerization started immediately after the start of irradiation. Irradiation was continued for 15 minutes to complete the polymerization. After cooling, the resulting gel polymer was cut with scissors and dried at 120 ° C. for 5 hours using a vacuum dryer. Next, the mixture was pulverized using a table-type pulverizer, and the water-soluble polymer having a neutralization degree of 30 mol% with an acrylic acid / sodium acrylate / methoxyethyl acrylate = 42.0 / 18.0 / 40.0 molar ratio according to the present invention (9 ) The water-soluble polymer (9) had a weight average molecular weight of 3,800,000 and an insoluble content of 4.5%. Met. Excavation stabilization liquid was prepared in the same manner as in Example 1 except that the water-soluble polymer (9) was used, and the evaluation of the excavation stabilization liquid was measured in the same manner as in Example 1. As a result, the funnel viscosity was 30.64 seconds and the drainage amount was 14.46 ml.

<Comparative Example 1>
In a beaker having a capacity of 500 ml, 36.94 g of acrylic acid, 58.18 g of 37% aqueous solution of sodium acrylate, and 51.82 g of ion-exchanged water were collected and mixed. The beaker containing the mixed solution was covered with Saran wrap, and dissolved oxygen in the mixed solution was removed by bubbling nitrogen while cooling. Next, 1.53 g of a sodium hypophosphite 3.0% aqueous solution as a chain transfer agent (0.06 g with respect to 1 mol of the total monomer composition) and Darocur (DC) 1173 (Ciba Subeshi) as a photopolymerization initiator while stirring. 1.53 g of 1% acrylic acid solution of Yarity Chemicals, chemical name; 2-hydroxy-2-methyl-1-phenyl-propan-1-one) (0.020 g relative to 1 mol of the total monomer composition) Was added to prepare a reaction solution. The monomer composition in the reaction solution was 70.0 mol% acrylic acid and 30.0 mol% sodium acrylate.

The total monomer concentration in the reaction solution was 40%, and the solution temperature was adjusted to 7 ° C. The reaction solution was irradiated for 15 minutes at a light intensity of 22 W / m ² using near ultraviolet rays (black light mercury lamp manufactured by Toshiba Corporation, model name H400BL-L) having a wavelength range of 300 to 450 nm. Polymerization started immediately after the start of irradiation. Irradiation was continued for 15 minutes to complete the polymerization. After cooling, the resulting gel polymer was cut with scissors and dried at 120 ° C. for 5 hours using a vacuum dryer. Subsequently, it grind | pulverized using the table-type grinder, and obtained the comparative water-soluble polymer (1) whose neutralization degree is 30 mol% by acrylic acid / sodium acrylate = 70.0 / 30.0 mol ratio which concerns on this invention. The comparative water-soluble polymer (1) had a weight average molecular weight of 1.83 million and an insoluble content of 1.43%. Met. Excavation stabilization liquid was prepared in the same manner as in Example 1 except that the comparative water-soluble polymer (1) was used, and the evaluation of the excavation stabilization liquid was measured in the same manner as in Example 1. As a result, the funnel viscosity was 35.24 seconds and the drainage amount was 18.26 ml.

<Comparative Example 2>
In a beaker having a capacity of 500 ml, 2.73 g of acrylic acid, 5.61 g of a 37% aqueous solution of sodium acrylate, 54.22 g of methoxyethyl acrylate, and 85.45 g of ion-exchanged water were collected and mixed. The beaker containing the mixed solution was covered with Saran wrap, and dissolved oxygen in the mixed solution was removed by bubbling nitrogen while cooling. Next, 0.98 g of a sodium hypophosphite 3.0% aqueous solution as a chain transfer agent (0.06 g with respect to 1 mol of the total monomer composition) and Darocur (DC) 1173 (Ciba Subeshi) as a photopolymerization initiator while stirring. 0.98 g of 1% acrylic acid solution of Yarity Chemicals, chemical name; 2-hydroxy-2-methyl-1-phenyl-propan-1-one) (0.020 g relative to 1 mol of the total monomer composition) Was added to prepare a reaction solution. The monomer composition in the reaction solution was 10.5 mol% acrylic acid, 4.5 mol% sodium acrylate, and 85.0 mol% methoxyethyl acrylate.

The total monomer concentration in the reaction solution was 40%, and the solution temperature was adjusted to 7 ° C. The reaction solution was irradiated for 15 minutes at a light intensity of 22 W / m ² using near ultraviolet rays (black light mercury lamp manufactured by Toshiba Corporation, model name H400BL-L) having a wavelength range of 300 to 450 nm. Polymerization started immediately after the start of irradiation. Irradiation was continued for 15 minutes to complete the polymerization. After cooling, the resulting gel polymer was cut with scissors and dried at 120 ° C. for 5 hours using a vacuum dryer. Then, it was pulverized using a table-type pulverizer, and a comparative water-soluble polymer (acrylic acid / sodium acrylate / methoxyethyl acrylate = 10.5 / 4.5 / 85.0 mol ratio and neutralization degree 30 mol%) according to the present invention ( 2) got. The comparative water-soluble polymer (2) had a weight average molecular weight of 1.47 million and an insoluble content of 0.04%. Met. Excavation stabilization liquid was prepared in the same manner as in Example 1 except that the comparative water-soluble polymer (2) was used, and the evaluation of the excavation stabilization liquid was measured in the same manner as in Example 1. As a result, the funnel viscosity was 21.22 seconds and the drainage amount was 21.32 ml.

<Comparative Example 3>
In a beaker having a capacity of 500 ml, 12.82 g of acrylic acid, 20.75 g of a 37% aqueous solution of sodium acrylate, 23.60 g of methoxyethyl acrylate, and 90.01 g of ion-exchanged water were collected and mixed. The beaker containing the mixed solution was covered with Saran wrap, and dissolved oxygen in the mixed solution was removed by bubbling nitrogen while cooling. Next, 1.91 g of a sodium hypophosphite 5.0% aqueous solution as a chain transfer agent (0.21 g with respect to 1 mol of the total monomer composition) and Darocur (DC) 1173 (Ciba Subeshi) as a photopolymerization initiator while stirring. 0.91 g of 1% acrylic acid solution of Yarity Chemicals, chemical name; 2-hydroxy-2-methyl-1-phenyl-propan-1-one) (0.020 g relative to 1 mol of the total monomer composition) Was added to prepare a reaction solution. The monomer composition in the reaction solution was 42.0 mol% acrylic acid, 18.0 mol% sodium acrylate, and 40.0 mol% methoxyethyl acrylate.

The total monomer concentration in the reaction solution was 30%, and the solution temperature was adjusted to 7 ° C. The reaction solution was irradiated for 15 minutes at a light intensity of 22 W / m ² using near ultraviolet rays (black light mercury lamp manufactured by Toshiba Corporation, model name H400BL-L) having a wavelength range of 300 to 450 nm. Polymerization started immediately after the start of irradiation. Irradiation was continued for 15 minutes to complete the polymerization. After cooling, the resulting gel polymer was cut with scissors and dried at 120 ° C. for 5 hours using a vacuum dryer. Next, the mixture was pulverized using a table-type pulverizer, and a comparative water-soluble polymer (acrylic acid / sodium acrylate / methoxyethyl acrylate = 42.0 / 18.0 / 40.0 molar ratio and a neutralization degree of 30 mol%) according to the present invention ( 3) got. The comparative water-soluble polymer (3) had a weight average molecular weight of 410,000 and an insoluble content of 0.02%. Excavation stabilization liquid was prepared in the same manner as in Example 1 except that the comparative water-soluble polymer (3) was used, and the evaluation of the excavation stability liquid was measured in the same manner as in Example 1. As a result, the funnel viscosity was 19.31 seconds and the drainage amount was 22.16 ml.

  The results of the above examples and comparative examples are summarized below. The funnel viscosity in the table is a value obtained by rounding off the measured values in Examples and the like to the second decimal place.

Abbreviations in the table are
AA: acrylic acid, AANa: sodium acrylate, AME: methoxyethyl acrylate, MAA: methacrylic acid, AAm: acrylamide.

  The excavation stabilizing liquid of the present invention preferably has a funnel viscosity (second) of 22 seconds to 32 seconds, more preferably 25 seconds to 30 seconds, and a drainage amount of 9 ml to 15 ml. If it is within this range, the excavation stable liquid has good stability and good workability.

  From the above results, in Comparative Example 1, the funnel viscosity and the drainage amount deviate significantly from the preferred ranges. In Comparative Examples 2 and 3, even if the funnel viscosity is about 19 to 21 seconds, the drainage amount greatly exceeds the preferable range, and a good drilling fluid cannot be obtained. This is considered to be because the polymer used in Comparative Example 2 was polymerized using AME in a predetermined amount or more. It can also be seen that when a polymer having a low weight average molecular weight is used as in Comparative Example 3, the amount of drainage increases greatly. In contrast to the comparative example, each of the examples is in a good region for both the funnel viscosity and the amount of drainage, and it can be seen that the performance of the excavation stabilizing liquid is better than the polymer used in the comparative example.

It is possible to efficiently and inexpensively provide a drilling stabilizing liquid that is resistant to spoilage, has no toxicity, and is excellent in viscosity and drainage. Furthermore, an excavation method using the excavation stabilizing liquid can be provided.
Further, it is possible to provide a drilling stabilizing liquid that is not toxic, has low viscosity, and is excellent in drainage.

Further, since the excavation stabilizing liquid of the present invention is an excavation stabilizing liquid containing a water-soluble polymer having good resistance to a substance containing a polyvalent metal ion, the water quality used for making the excavation stabilizing liquid is as follows. Water with high salinity such as waste water and seawater can be used. In addition, even if an inorganic substance such as cement is mixed in the drilling stability liquid, there is an effect that the muddy water performance does not change, so that a drilling stability liquid that can be used in a more stable state at various drilling sites is obtained. Can do.

Claims (5)

(Meth) acrylic acid (salt) (A) 20 to 99 mol% and (meth) acrylic acid ester monomer (B) 1 to 80 mol% represented by the following general formula (1) are essential. The other monomer (C) copolymerizable with the above (A) and (B) is 0 to 20 mol% (provided that the total amount of (A), (B) and (C) is 100 mol%. A drilling stabilizing liquid comprising a water-soluble polymer (P) having a weight average molecular weight of 500,000 or more obtained by polymerizing a monomer group consisting of water) and water.
_{CH 2 = C (R) -COOZ} 1 (O) P Z 2 OX (1)
(Wherein R represents a hydrogen atom or a methyl group, Z ¹ and Z ² each represent an alkylene group having 8 or less carbon atoms, X represents a hydrocarbon group having 4 or less carbon atoms, and P represents an integer of 0 or 1) 2. The excavation stabilizing liquid according to claim 1, wherein the water-soluble polymer (P) has a weight average molecular weight of 700,000 to 4,000,000. The excavation stabilizing liquid according to claim 1 or 2, wherein an insoluble content of the water-soluble polymer (P) is 5% by weight or less. 4. The excavation stabilizing liquid according to claim 1, further comprising a viscous mineral. An excavation method using the excavation stabilizing liquid according to any one of claims 1 to 4 to excavate the ground while preventing collapse of the inner wall surface of the excavation hole.