JP3224533B1 - Paint for friction reducing agent and negative friction cut method, latent box method and propulsion method using the same - Google Patents

Abstract

An object of the present invention is to, for example, apply a material to various substructures (H steel, steel sheet piles, concrete piles, steel pipe piles, etc.) in advance so that the base material surface when buried in the ground can be obtained. Provided is a friction reducing agent paint for reducing friction with soil and facilitating embedding. A water-absorbent resin (a) and an alkali-water-soluble binder resin (b) when performing various types of substructure negative friction cut method, latent box method, and propulsion method.
(Or a binder resin (d) having an acid value of 40 to 500 mgKOH / g) and a solvent (c) for a friction-reducing agent paint as essential components for various foundation structures (steel sheet piles, concrete piles, steel pipe piles, etc.) ), Previously applied to various tanks, water storage tanks, fume pipes, steel pipes, steel pipe piles (base material), etc. As an effect, a sustained and sustained friction reduction effect between the soil and the foundation structure is exhibited, and the construction time can be reduced. Further, ground displacement can be absorbed over a long period of time, and a building or the like on the foundation structure can be stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a submersion method for burying various tanks, water tanks, etc. in the ground when burying various basic structures, and a method for burying various fume pipes, steel pipes, steel pipe piles and the like. By applying in advance to various substructures, various tanks, water storage tanks, fume pipes, steel pipes, steel pipe piles (base material), etc. when performing the propulsion method when burying (horizontal, vertical) inside , Reduces the friction between various foundation structures and the ground, preventing ground damage due to changes in the surrounding ground due to land subsidence, and reducing the friction between the base material surface and soil when buried in the ground And a friction-reducing agent paint for facilitating burial (speed-up of burial, reduction of the pushing force at the time of burying, etc.), and a negative friction cutting method, a latent box method, and the like for a substructure using the friction reducing agent. Regarding the propulsion method.

[0002]

2. Description of the Related Art Conventionally, a submersion method, a propulsion method, and the like for burying a substructure buried underground and various base materials (tanks, water storage tanks, fume pipes, steel pipes, steel pipe piles, etc.) in the ground have been used. In addition, various problems have been caused by friction between the soil and the substructure or various base materials.

[0003] For example, a substructure buried underground is
When the surrounding ground caused land subsidence, there was a problem that the foundation structure was damaged due to friction (negative friction) between the surface of the foundation structure and the surrounding ground.

In the submersion method in which the tanks are sunk into the ground by excavating the soil on the lower surface of the tanks, no earth retaining wall is used. There was a problem that the earth pressure was applied to the side of the tank, making it extremely difficult to sink.

On the other hand, in the propulsion method and the like, if the friction between the base material (such as steel pipe) and the soil is large, it is difficult to push the base material. Therefore, a lubricant (a bentonite / water mixture) is usually provided around the base material. And the like), but such a lubricant has problems such as lowering the strength of the surrounding ground and necessitating post-processing of the lubricant.

[0006] To solve these problems,
Various solutions have been considered. For example, JP
In Hei 4-23514, specified between the substructure and soil
The film configuration ofFilm: (contact with substructure)
Wear) / Lubricant (oil etc.) / Film: (Soil side),When
By sandwiching the film configuration described above,
Can also reduce the friction between the substructure and the soil (negative
(Reaction cut method) has been proposed
However, in the case of this construction type, first the substructure
If it is driven by a method such as
The above film composition peels off, and the effect of sufficient friction reduction
And the effect of sustained friction reduction cannot be demonstrated.
There was a fatal defect. In addition, due to its structure,
Up to the film before construction due to slight friction
There is a problem that it is difficult to handle
Was.

In Japanese Patent Publication No. 6-39784, the friction between the substructure and the soil is reduced by pre-coating a substructure such as a pile with a water-in-oil type water-swellable polymer particle emulsion or an aqueous dispersion thereof. It has been proposed that this can be done, but in the case of this type of construction as well, if the substructure is first driven by the submersion method or the propulsion method, it will fall off when it is driven. There were defects. Furthermore, after application to the substructure, the coating of the emulsion or the aqueous dispersion thereof is easily peeled off from the substructure by contact with the surroundings, and similarly, the effect of reducing friction and the effect of maintaining sufficient friction are maintained. There is a problem in that handling is difficult, for example, it is not possible to exhibit an effective effect of reducing friction.

On the other hand, in Japanese Patent Application Laid-Open No. 63-27619, a mixture comprising a water-swellable powder (gelatin, agar, etc.) / A resin capable of forming a film and supplying water (polyvinyl butyral) / organic solvent was applied to the substructure. It is described that by installing a substructure in the ground, after burying in the ground, the coating film swells due to moisture in the ground and reduces friction between the substructure and the soil.

However, in this method, the balance between the swelling ratio and the strength of the water-absorbent resin is low, and the balance between the adhesive strength of the binder resin to the steel material and the film strength is poor (weak adhesive strength and strong film strength). 1) The coating film easily peels off from the substructure during casting (the coating film does not remain when buried in the soil, and the friction reducing function cannot be sufficiently exhibited). 2)
Insufficient film strength when swollen, lack of sustained release of friction reducing layer (swelling layer) when used in latent box method, propulsion method, etc. Specifically, there is no sustained friction reducing effect There were drawbacks.

As described above, a friction reducing agent which can be used in negative friction cutting method, latent box method, propulsion method and the like of a substructure, and hardly peels at the time of burying regardless of the burying method. After embedding (time), there is no good friction-reducing agent that exerts a good friction-reducing function and that the friction-reducing agent is supplied in a sustained-release manner. Was.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to easily construct a base material buried in the ground, Even when casting by the latent box method, propulsion method, etc., the entire friction reducing agent coating film does not peel off from the substrate regardless of the driving method (the swelling friction reducing agent layer on a part of the surface depending on the application reduces friction) The coating surface swells due to moisture given beforehand or absorbed from the ground during burial, during the submersion method, during the propulsion method, or swelling (a friction reducing agent). The layer can be gradually released between the substrate and the soil, and its sustained release can be controlled by adjusting the hydrophilicity of the binder resin, the thickness of the coating film, etc., so that it can be applied to soils of various properties. It is to provide a paint for a reducing agent.

Furthermore, by using the above-mentioned paint for a friction reducing agent, the friction between the substructure buried underground and the surrounding ground is cut, and the influence of the change of the surrounding ground on the substructure is reduced. Negative friction cut method of the substructure that can be made possible and the submersion method, which can reduce the frictional force between the base material and the soil while minimizing the effect on the surrounding ground, and can significantly improve the speed and efficiency of construction, promotion It is to provide a construction method.

[0013]

Means for Solving the Problems In order to solve the above-mentioned conventional problems, the inventor of the present invention adhered well to a base material used for a negative friction cut method, a latent box method and a propulsion method of a substructure, and was provided with a short term. All parts are not peeled off at once, and the friction is released gradually for a required period (under the construction method in the latent box method or the propulsion method, that is, during burying), or in the negative friction cut method over a long period after burying. We studied diligently a paint for a friction reducing agent that can supply a reducing agent layer and maintain the friction reducing effect. In other words, the present inventors have intensively studied a paint for a friction reducing agent that can continuously maintain the friction reducing effect. As a result, as a paint for friction reducing agent,
A specific composition such that the water-absorbent resin (a), the alkaline water-soluble binder resin (b) (or the binder resin (d) having an acid value of 40 to 500 mgKOH / g) and the solvent (c) are essential components. It has been found that the above-mentioned problems can be solved by previously applying the blended paint for a friction reducing agent to a substrate, and the present invention has been completed.

By adopting the above configuration, it can be used by applying it to the base material of various construction methods and the like, and at the time of embedding or after embedding, it exhibits a frictional reduction effect by removal, in other words, a continuous friction reduction effect. It is possible to supply a paint for a friction reducing agent as possible. Further, it is possible to provide a method of applying various base materials using the above-mentioned paint for a friction reducing agent. With the above construction method,
Specifically, it is a burial method, and a specific example of the above construction method is a negative friction cut method for an underground structure. Further, the above-mentioned paint for a friction reducing agent of the present invention can be adapted to a latent box method or a propulsion method.

First, the paint for a friction reducing agent of the present invention will be described below. Water absorbent resin (a) used in the present invention
Is swollen by absorbing water, and the absorption capacity of ion-exchanged water with respect to its own weight is 3 times or more (25 ° C., 1
The time is not particularly limited. However, a synthetic water-absorbent resin obtained by crosslinking a water-soluble or hydrophilic compound (monomer and / or polymer) with a crosslinking agent, which is exemplified below, has a higher swelling ratio and water swelling ratio than natural water-swellable substances (gelatin, agar, etc.). It has a good balance of solubles, water absorption rate, strength, etc., and these are more natural water swellable substances (gelatin,
Agar, etc.).

As the water-absorbing resin (a) as described above,
Specifically, for example, cross-linked poly (meth) acrylic acid,
Cross-linked poly (meth) acrylate, cross-linked poly (meth) acrylate having a sulfonic group, cross-linked poly (meth) acrylate having a polyoxyalkylene group, cross-linked poly (meth) acrylamide, Meta)
Crosslinked copolymer of acrylate and (meth) acrylamide, hydroxyalkyl (meth) acrylate and (meth)
Cross-linked copolymer with acrylate, cross-linked polydioxolane, cross-linked polyethylene oxide, cross-linked polyvinyl pyrrolidone, cross-linked sulfonated polystyrene, cross-linked polyvinyl pyridine, saponified starch-poly (meth) acrylonitrile graft copolymer, starch- Poly (meth) acrylic acid (salt) graft crosslinked copolymer, reaction product of polyvinyl alcohol and maleic anhydride (salt), crosslinked polyvinyl alcohol sulfonate, polyvinyl alcohol-acrylic acid graft copolymer, polyisobutylene maleic Acid (salt) cross-linked polymers and the like. One of these water-absorbing resins may be used alone, or two or more thereof may be used in combination.

In the present invention, it is preferable to use a salt-resistant water-absorbing resin as the water-absorbing resin (a). The reason why the salt-resistant water-absorbent resin is preferable is that the salt-resistant water-absorbent resin has a relatively high water absorption ratio of hard water containing a polyvalent metal, and when used for a friction-reducing agent paint, is largely affected by the water quality in the soil. This is because a friction reducing effect can be exhibited.

The salt-resistant water-absorbent resin of the present invention is not particularly limited as long as it has a water absorption capacity of 10 times or more in artificial seawater (25 ° C., 24 hours). Among the resins (a), those having a nonionic group and / or a sulfonic acid (salt) group are more preferable, and those having an amide group or a hydroxyalkyl group are still more preferable. As the salt-resistant water-absorbing resin as described above,
For example, a cross-linked copolymer of (meth) acrylate and (meth) acrylamide, a cross-linked copolymer of hydroxyalkyl (meth) acrylate and (meth) acrylate, and the like can be given. Further, those having a polyoxyalkylene group are particularly preferred. Examples of such a water-absorbent resin (a) include a crosslinked copolymer of a (meth) acrylate having a methoxypolyoxyalkylene group and a (meth) acrylate.

The use of these salt-resistant water-absorbent resins makes it possible to obtain the properties of water in the soil (soft water, hard water, etc.).
Swells to a certain magnification regardless of the above, and can more reliably exhibit the friction reducing function.

Further, the water-absorbent resin (a) according to the present invention
The method for producing is not particularly limited, and examples thereof include a method of polymerizing a monomer component containing a water-soluble ethylenically unsaturated monomer and, if necessary, a crosslinking agent. The water-absorbent resin (a) obtained by (co) polymerizing an ethylenically unsaturated monomer is more excellent in water absorbency with respect to water, and
Generally inexpensive. In addition, the above-mentioned crosslinking agent is not particularly limited.

The above ethylenically unsaturated monomers include:
Specifically, for example, acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, citraconic acid, vinylsulfonic acid, (meth) allylsulfonic acid,
2- (meth) acrylamide-2-methylpropanesulfonic acid, 2- (meth) acryloylethanesulfonic acid,
2- (meth) acryloylpropanesulfonic acid, and alkali metal salts and ammonium salts of these monomers;
N, N-dimethylaminoethyl (meth) acrylate,
And quaternary compounds thereof; (meth) acrylamide, N,
(Meth) acrylamides such as N-dimethyl (meth) acrylamide, 2-hydroxyethyl (meth) acrylamide, diacetone (meth) acrylamide, N-isopropyl (meth) acrylamide, (meth) acryloylmorpholine, and monomers thereof A hydroxyalkyl (meth) acrylate such as 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate; polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, methoxypolyethylene glycol mono ( Polyalkylene glycol mono (meth) acrylates such as meth) acrylate and methoxy polypropylene glycol mono (meth) acrylate; N-vinyl-
N-vinyl monomers such as 2-pyrrolidone and N-vinylsuccinimide; N-vinylformamide, N-vinyl-N
-Methylformamide, N-vinylacetamide, N-
N-vinylamide monomers such as vinyl-N-methylacetamide; vinyl methyl ether; and the like, but are not particularly limited. These ethylenically unsaturated monomers may be used alone or in combination of two or more.

Among the ethylenically unsaturated monomers exemplified above, those composed of an ethylenically unsaturated monomer having a nonionic group and / or a sulfonic acid (salt) group are more preferred because of their high salt resistance. Examples of the monomer include 2
-(Meth) acrylamide-2-methylpropanesulfonic acid, 2- (meth) acryloylethanesulfonic acid, 2
-(Meth) acryloylpropanesulfonic acid, (meth)
Acrylamide, hydroxyalkyl (meth) acrylate, methoxypolyethylene glycol mono (meth) acrylate and the like can be mentioned. Further, an ethylenically unsaturated monomer having a polyoxyalkylene group is particularly preferred.

When two or more ethylenically unsaturated monomers are used in combination as a monomer component, a more preferred combination is, for example, a combination of an alkali metal (meth) acrylate such as sodium acrylate and acrylamide. And a combination of an alkali metal salt of (meth) acrylic acid and methoxypolyethylene glycol mono (meth) acrylate, but are not particularly limited.

By polymerizing the above monomer components,
The water-absorbent resin (a) is obtained. In addition, the water absorbent resin (a)
The average molecular weight, shape, average particle diameter, etc. of the water-absorbent resin (a) may be set according to the composition of the friction reducing agent, the type of binder, the physical properties, the working environment, and the like. The average particle size is preferably 30 to 800 μm,
It is more preferably from 30 to 600 μm, most preferably from 30 to 400 μm.

When the average particle size of the water-absorbent resin (a) used in the present invention exceeds 800 μm, the particle size is too large, and the alkali water-soluble binder resin (b) (or the acid value of 40) is used.
Binder resin (d) having a concentration of up to 500 mg KOH / g)
When the water-absorbent resin (a) is mixed with the solvent (c) solution, the particles of the water-absorbent resin (a) tend to settle, which is not preferable. On the other hand, the average particle diameter of the water-absorbent resin (a) is 30 μm.
If it is less than m, handling becomes extremely difficult (such as easy scattering as fine powder), which is not preferable.

Hereinafter, the alkaline water-soluble binder resin (b) of the present invention will be described. The alkaline water-soluble binder resin (b) constituting the paint for a friction reducing agent of the present invention is a resin that is soluble in a 0.4% by weight aqueous solution of NaOH and does not dissolve in neutral or acidic water.
The alkali water-soluble resin is not particularly limited as long as it has the solubility specified above. For example, copolymerization of an α, β-unsaturated carboxylic acid monomer and another monomer copolymerizable therewith. Coalescence can be mentioned.

Although the solubility in alkaline water is as described above, the degree of solubility is not particularly limited, but the alkali water-soluble binder resin (b) as a binder resin that can be preferably used in the present invention will be described later. Indicates the degree of dissolution. In addition, the term “alkali water-soluble resin” of the present invention may be expressed as an alkali-soluble resin in another expression. Since it is clearer to use an alkali water-soluble resin, in the present invention, the resin was used as an alkali water-soluble resin.

The solubility of the alkaline water-soluble binder resin (b), which can be preferably used in the present invention, in alkaline water is not limited as long as the characteristics of the present invention are not impaired.
There is no particular limitation.

For example, it can be defined by the weight reduction rate of the alkali water-soluble resin in the following solubility test. The solubility of the alkaline water-soluble binder resin (b) which can be preferably used in the present invention in alkaline water is, for example, a molded product of the alkaline water-soluble binder resin (b) having a shape of 5 mm or less (for example, see Examples). Like 3
mm pellet shape, even if it is not pelletized
What is necessary is just to cut etc. so that it may become a size below mm. ),
10 g of a 0.4% strength by weight aqueous solution of NaOH 500
g of the binder resin and stirred at 25 ° C. for 24 hours.

That is, if there is any resin remaining without being dissolved after stirring for 24 hours, the resin is filtered and the like, washed with water, and the weight after drying is determined. Before being subjected to the solubility test, it can be determined by the rate of decrease from the weight of the original alkaline water-soluble binder resin (b). That is, the ratio can be determined by the ratio of <original weight−weight after solubility test> / <original weight> expressed in%.

The value of the alkali water-soluble binder resin (b) of the present invention is preferably 50% -10%.
0%. More preferably, it is 60-100%.
More preferably, it is 70-100%.

The acid value of the alkali water-soluble binder resin (b) is not particularly limited, but is preferably at least 40 mgKOH / g, more preferably at least 50 mgKOH / g in order to have an appropriate hydrophilicity. ,
More preferably, it is 70 mgKOH / g or more. When the acid value of the alkaline water-soluble binder resin (b) is less than 40, the hydrophilicity of the alkaline water-soluble binder resin (b) is too low, so that the swelling of the water-absorbent resin at the time of absorbing water is restricted, and the alkali-water-soluble resin is insufficient. The effect of reducing friction is less likely to be exhibited.

In order to maintain the binder function when absorbing water, the acid value of the alkaline water-soluble binder resin (b) is preferably not more than 500 mgKOH / g, preferably 3 mgKOH / g.
00 mgKOH / g or less, more preferably 20 mgKOH / g or less.
More preferably, it is 0 mgKOH / g or less. The acid value of the alkaline water-soluble binder resin (b) is 500 m
If it exceeds gKOH / g, the hydrophilicity of the alkaline water-soluble binder resin (b) becomes too high, so that the adhesion of the coating film at the time of absorbing water is insufficient, and the entire coating film for the friction reducing agent is easily peeled off. In addition, it is difficult to exhibit functions such as sufficient friction reduction effect, maintenance of friction reduction effect, and sustained release.

Next, the glass transition temperature of the alkaline water-soluble binder resin (b) is not particularly limited, but the adhesion to the substrate and the workability when the substrate is buried in the soil,
From the viewpoint of compatibility of the toughness of the paint film for friction reducer,
It is preferred to have a glass transition temperature between 20C and 120C. When the glass transition temperature is −20 ° C. or lower, the coating film for the friction reducing agent tends to be sticky, and blocking may occur particularly when the coated substrates are left standing after being stacked. Further, since the strength of the friction reducing agent coating is insufficient, the base material is easily peeled off when buried in the soil, which is not preferable. From this, it is more preferable that the glass transition temperature is 0 ° C. or higher.

On the other hand, if the glass transition temperature is 120 ° C. or higher, the anti-adhesive layer becomes too hard, and the adhesion to the substrate and the flexibility of the friction-reducing agent coating film become poor. At the time of embedding, it is not preferable because peeling and falling off of the water-absorbent resin (a) easily occur. From this fact, it is more preferable that the glass transition temperature is 100 ° C. or lower, and if the glass transition temperature is between 0 ° C. and 20 ° C. and between 20 ° C. and 100 ° C., respectively, the softening component and the shape maintaining component may Good balance is more preferable.

The weight average molecular weight (Mw) of the alkaline water-soluble binder resin (b) is not particularly limited, but is preferably in the range of 30,000 to 300,000.
The range of 50,000 to 200,000 is more preferable.
By using the resin having the above-mentioned weight average molecular weight, it becomes easy to balance the toughness of the anti-adhesion material with the solubility in alkaline water.

In the following, the acid value of the present invention is 40 mgKOH / g.
The binder resin (d) having a concentration of about 500 mgKOH / g will be described.

The binder resin (d) of the present invention is not particularly limited as long as it has an acid value of 40 to 500 mgKOH / g and has a binder function of fixing the water-absorbent resin (a) to the substrate.

The acid value of the present invention is 40 to 500 mg KOH /
g of the binder resin (d) has an acid value of 40 mg KOH
If it is less than / g, the hydrophilicity of the binder resin (d) is too low, so that the swelling of the water-absorbent resin at the time of water absorption is restricted, and a sufficient friction reducing effect cannot be exhibited. Further, when the acid value of the binder resin (d) of the present invention having an acid value of 40 to 500 mgKOH / g exceeds 500 mgKOH / g, the hydrophilicity of the binder resin (d) becomes too high. Adhesion is insufficient, and the entire coating film for the friction-reducing agent is easily peeled off, so that functions such as a sufficient friction-reducing effect, maintenance of the friction-reducing effect, and sustained-release properties cannot be exhibited.

The alkaline water-soluble binder resin (b) of the present invention, specifically, has an acid value of 40 to 500 mg KOH /
Although the method for producing the binder resin (d) is not particularly limited, a monomer other than the following α, β-unsaturated carboxylic acid monomer and an α, β-unsaturated carboxylic acid monomer copolymerizable therewith can be used. A copolymer which can be obtained by polymerization using an unsaturated monomer component composed of a polymer is preferable.

For example, α, β-unsaturated carboxylic acid monomers used in the production include, for example, acrylic acid,
Α, β-unsaturated carboxylic acids such as methacrylic acid, maleic acid, itaconic acid and fumaric acid; α, β-unsaturated carboxylic acid anhydrides such as maleic anhydride and itaconic anhydride; maleic acid monoester, fumaric acid monoester And α, β-unsaturated dicarboxylic acid monoesters such as esters and itaconic acid monoesters. The α, β-unsaturated carboxylic acid monomer may be only one kind or two or more kinds. Of these, acrylic acid and / or methacrylic acid, which are acrylic α, β-unsaturated carboxylic acids, are preferably used because they are inexpensive and have good copolymerizability with other unsaturated monomers.

Other monomers copolymerizable with the α, β-unsaturated carboxylic acid monomer include, for example, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, stearyl acrylate, methyl methacrylate, ethyl methacrylate Esters of monohydric alcohols having 1 to 18 carbon atoms with (meth) acrylic acid, such as methacrylate, propyl methacrylate, butyl methacrylate, and stearyl methacrylate; acrylonitrile;
Nitrile group-containing vinyl monomers such as methacrylonitrile; amide group-containing vinyl monomers such as acrylamide and methacrylamide; hydroxyl-containing vinyl monomers such as hydroxyethyl acrylate and hydroxypropyl methacrylate; glycidyl methacrylate and the like Epoxy group-containing vinyl monomers; metal salts of α, β-unsaturated carboxylic acids such as zinc acrylate and zinc methacrylate; styrene, α
-Aromatic vinyl monomers such as methylstyrene; aliphatic vinyl monomers such as vinyl acetate; halogen-containing vinyl monomers such as vinyl chloride, vinyl bromide, vinyl iodide, and vinylidene chloride; allyl ether Maleic acid derivatives such as dialkyl esters of maleic acid; fumaric acid derivatives such as dialkyl esters of fumaric acid; maleimide derivatives such as maleimide, N-methylmaleimide, stearylmaleimide, N-phenylmaleimide, N-cyclohexylmaleimide; itaconic acid Mono- and dialkyl esters, itaconic amides, itaconic imides, itaconic amide esters and other itaconic acid derivatives; alkenes such as ethylene and propylene; dienes such as butadiene and isoprene; vinyl ethers; 2- (meth) acryloylpropane Sulfone (Salt), 3-allyloxy-2
Examples thereof include unsaturated monomers having a sulfonic acid (salt) group such as hydroxypropanesulfonic acid (salt), polyalkylene glycol (meth) acrylates, and the like, and one or more of these are used. be able to.

Among these, as the alkyl (meth) acrylate, esters having various properties can be easily obtained, and by appropriately combining them, the Tg (hardness, softness) of the binder resin can be obtained. It is preferable because the adhesion to the substrate can be easily adjusted and the copolymerizability with the α, β-unsaturated carboxylic acid monomer is relatively good.

The above alkyl (meth) acrylate is used in an amount of from 30% by weight to 1% by weight, based on 100% by weight of the total amount of other monomers copolymerizable with the α, β-unsaturated carboxylic acid monomer.
It is preferably used at 00% by weight, more preferably at least 50% by weight to 100% by weight. More preferably 60 to 100% by weight, even more preferably 70 to 100% by weight.
100% by weight. That is, the use of an acrylic monomer as another monomer is a preferred embodiment as the form of the alkaline water-soluble binder resin (b) of the present invention.

The ratio of the above-mentioned α, β-unsaturated carboxylic acid monomer and the unsaturated monomer component composed of another monomer copolymerizable therewith is not particularly limited.
When the unsaturated monomer component comprising an unsaturated carboxylic acid monomer and another monomer copolymerizable therewith is defined as 100% by weight, α, β-unsaturated carboxylic acid in all monomer components is The proportion is preferably 7 to 80% by weight based on the total amount of the unsaturated monomer. More preferably, it is 7 to 50% by weight. More preferably, it is 9 to 30% by weight.

When the proportion of the α, β-unsaturated carboxylic acid monomer in all the monomers in the alkaline water-soluble binder resin (b) is less than 7% by weight, the acid value becomes low and the hydrophilicity is lowered. Tends to be too low. On the other hand, if the proportion exceeds 80% by weight, problems tend to occur because the hydrophilicity becomes too high.

The acid value of the present invention is 40 to 500 mg KOH.
/ G of binder resin (d), that is, a copolymer other than the α, β-unsaturated carboxylic acid monomer used as a raw material in the case of producing a binder resin obtained by polymerizing the unsaturated monomer component described above. The possible amount of the monomer is preferably based on 100% by weight of the total amount of the unsaturated monomer composed of the above α, β-unsaturated carboxylic acid monomer and another monomer copolymerizable therewith. Represents 93 to 20% by weight of the total components of the unsaturated monomer. More preferably, it is 93 to 50% by weight. More preferably, it is 91 to 70% by weight.

When the proportion of the above α, β-unsaturated carboxylic acid monomer is less than 20%, the hydrophilicity is not easily lowered, and when the proportion is more than 93%, the hydrophilicity becomes too high, which is preferable. Absent.

An alkaline water-soluble binder resin (b),
Specifically, the method for producing the binder resin (d) having an acid value of 40 to 500 mgKOH / g is not particularly limited, and generally known polymerization methods such as solution polymerization, bulk polymerization, emulsion polymerization, and suspension polymerization can be used. Among them, production by solution polymerization in an organic solvent is preferred.

This is because the alkaline water-soluble binder resin (b) obtained by solution polymerization, specifically, an acid value of 40 to 5
This is because by directly mixing the water-absorbing resin with a solution or dispersion containing the binder resin (d) of 00 mg KOH / g, it is possible to produce the friction reducing agent coating of the present invention.

The polymerization forms include radical polymerization,
Examples thereof include anionic polymerization, cationic polymerization, and coordination polymerization, and radical polymerization is preferable as an industrial production method.

Examples of the reaction vessel used for producing the raw material polymer include a tank reactor, a kneader, and a tubular reactor such as a static mixer. These reactors can be used together if necessary. A dropping tank is also used as needed. The pressure in the reaction vessel may be any of reduced pressure, normal pressure, and pressurized.

Next, the radical polymerization initiator used in the radical polymerization is not particularly limited, but specific examples thereof include 2,2′-azobisisobutyronitrile,
Examples include azo initiators such as 2,2'-azobis (2,4-dimethylvaleronitrile); and peroxide initiators such as benzoyl peroxide and di-t-butyl peroxide. These radical polymerization initiators are 2
More than one type may be used in combination.

The solvent used in the solution polymerization is not particularly limited as long as it does not hinder the radical polymerization reaction.
For example, alcohols such as methanol, ethanol and isopropyl alcohol; aromatic hydrocarbons such as benzene and toluene; ketones such as acetone and methyl ethyl ketone; aliphatic esters such as ethyl acetate and butyl acetate;
Examples thereof include ethylene glycol derivatives such as ethylene glycol and ethylene glycol monomethyl ether, and propylene glycol derivatives such as propylene glycol monomethyl ether and propylene glycol monomethyl ether acetate. Two or more of these solvents may be used in combination.

Next, the solvent (c) used in the present invention will be described.

The solvent (c) can be used without any particular limitation as long as it is a known solvent used in ordinary paints and the like. For example, the alkali water-soluble binder resin (b), specifically, an acid value 40-500mgKOH / g
The solvents and the like exemplified in the description of the method for producing the binder resin (d) can be used alone or in combination of two or more.

As a method for selecting the solvent (c), it is preferable to select a solvent having a boiling point, safety and the like suitable for application to a substrate. If a solvent having a low boiling point is selected, it has a quick drying property, and a coating film can be formed in a short time, so that a thick coating or the like can be easily performed. If a solvent having a high boiling point is selected, the working time can be lengthened. By using an organic solvent as a medium, there is no swelling due to water absorption of the water-absorbent resin that occurs when a medium containing water is used, and the coating operation is facilitated because the resin does not become a gel. In addition, when a highly volatile solvent such as methyl ethyl ketone or methanol is used, it is dried in about 10 minutes, and since it dries much faster than when water is used as a medium, it is possible to quickly shift to the next operation or process. The work period or the time required for application to the substrate can be significantly reduced.

The paint for a friction reducing agent of the present invention comprises the water-absorbent resin (a) and the alkali water-soluble binder resin (b) (or an acid value of 40 to 500 mgKOH /
g) as a binder resin (d)) and a solvent (c) as essential components, other additives (h) as other additives such as resins, pigments, various stabilizers, It may contain a filler or the like.

The water-absorbent resin (a) and the alkaline water-soluble binder resin (b) (or an acid value of 40 to 500 mg KO)
H / g binder resin (d)) and solvent (c)
The ratio of the and other additives (h) is not particularly limited,
In order to fully exhibit the features of the paint for a friction reducing agent of the present invention, the water-absorbent resin (a), the alkali water-soluble binder resin (b) (or the acid value of 40 to 500 mgKOH /
g of the binder resin (d)) and the solvent (c), and the weight ratio ([(a) + ((b)
Or (d)) + (c)] / [(a) + ((b) or (d)) + (c) + (h)] × 100 (%). ) Is preferably 50% or more, more preferably 70% or more, and most preferably 80% or more.

Further, the water-absorbent resin (a) and the alkaline water-soluble binder resin (b) (or an acid value of 40 to 500 m
The ratio of the binder resin (d), which is gKOH / g), the solvent (c), and the other additives (h) is also not particularly limited. 5 to 60% by weight of the water-absorbent resin (a), 10 to 70% by weight of the alkaline water-soluble binder resin (b) (or the binder resin (d) having an acid value of 40 to 500 mgKOH / g), ) Is preferably from 5 to 70% by weight, the other additives (h) are preferably from 0 to 50% by weight, the water-absorbent resin (a) is from 10 to 50% by weight, the alkali water-soluble binder resin (b) (or the acid value is 40-50
0 mgKOH / g binder resin (d)) is 10
More preferably, the solvent (c) is 10 to 60% by weight, and the other additives (h) are 0 to 30% by weight.

The method of applying the coating material for a friction reducing agent of the present invention to various substrates is not particularly limited as long as it is a known coating method. For example, a brush or a roller may be used. Spray painting may be performed using a spray device such as ricin gun.

The substrate or substrate to which the present invention is applied includes:
Underground structures, known bases and base materials used in the submersion method and the propulsion method are not particularly limited, for example, pipes such as steel pipes and fume pipes, steel sheet piles (sheet piles),
Piles such as corrugated sheets, H-shaped steels, I-shaped steels, steel pipe piles, iron columns, concrete piles, poles, etc., various tanks and water tanks mainly used in the latent box method, and the like.

One of the important features of the coating material for a friction reducing agent of the present invention is that the friction reducing agent layer can be supplied gradually. That is, the fact that the friction reducing effect is maintained is also a feature of the friction reducing agent paint of the present invention.

There is no particular limitation on the form of the substrate or the substrate. For example, excavating a hole in the ground, hanging the base steel or the like with a crane, etc., installing and burying it, or casting and pushing the base like the latent box method or the propulsion method You can adopt it.

As a mechanism, since the water absorption of the paint film for the friction reducing agent gradually proceeds from near the surface, the alkali water-soluble binder resin (b) (or the acid value of 40 to 40) is used.
The hydrophilicity of the binder resin (d) of 500 mgKOH / g, the water-absorbent resin (a) and the alkaline water-soluble binder resin (b) (or an acid value of 40 to 500 mgKOH / g)
/ G of the binder resin (d)), it is possible to set a desired water absorption rate under each construction condition. By absorbing an appropriate amount of soil moisture from the paint film surface, a new friction reducing agent layer (water absorption swelling layer) is supplied to the substrate surface over many days, that is, over a long period of time. That is.

For example, a specific example of sustained release is as follows.
It is as follows. The friction reducing agent of the present invention is applied to a substrate 1 (for example, a steel pipe), and only a part of the surface is absorbed and swelled to form a friction reducing agent layer 1, and then the substrate 1 (for example, a steel pipe 1) is formed. Is poured into the soil (day 1), the friction reducing agent layer 1 functions as a friction reducing agent, and peels off from the surface of the substrate 1 (for example, the steel pipe 1).

However, by the next day of construction, the surface of the base material near the surface of the friction reducing agent absorbs and swells the moisture in the soil, and a new friction reducing agent layer 2 is formed. Further, on the second day, when the base material 2 (for example, the steel pipe 2) is cast from the ground in the same manner as yesterday, and the base material 1 (for example, the steel pipe 1) is further pushed deep into the soil, the friction reducing agent layer 2 Functions as a friction reducing agent and peels off from the substrate 1 (for example, the steel pipe 1). By repeating this phenomenon, even in the case of a base material (for example, steel pipe, etc.) such as a propulsion method in which casting is repeated for many days in the soil, the paint for a friction reducing agent of the present invention is once grounded. Simply by applying it to the material, it will be possible to exert its friction reducing function in the soil throughout the construction. In addition, the above is an example of the case where the base material or the base material is buried by casting or the like.

Further, the paint for a friction reducing agent of the present invention employs a specific compounding composition, so that the coating composition of the present invention is excellent in removing the friction reducing effect. That is, the friction-reducing effect is excellent in persistence, and even after embedding, even for a long time, the soil, the base material, the base material, and the substructure to which the paint for the friction-reducing friction-reducing agent of the present invention is applied. Since the effect of reducing friction between the grounds is maintained, even if the ground and the like fluctuate, the above-described friction reducing effect can minimize the fluctuation and displacement of the base material and the base material on the ground. As a result, a building such as a building on a base material or a base or a substructure is stabilized. For example, even when a base material, a base material, or a substructure is constructed in a hole in the soil with a crane or the like,
The effect of reducing friction between the soil and the base material or the base material can be maintained for a long period of time. Therefore, it can be preferably implemented as a negative friction cut method.

[0069]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. The acid value of the alkaline water-soluble binder resin (b) was measured based on the test method described in the application clause 4.3 of JIS K6901 “Test method for liquid unsaturated polyester resin”. However, when the hydrophilic binder resin (b) did not dissolve in the solvent specified in the test method, the measurement was carried out in accordance with the above test method, using a suitable solvent to dissolve the hydrophilic binder resin.

The glass transition temperature of the alkali water-soluble binder resin (b) was measured using a DSC 220C manufactured by Seiko Denshi Kogyo Co., Ltd. under a nitrogen atmosphere according to “JIS K
7121 Plastic transition temperature measurement method ". In addition, the condition adjustment of the test specimen was performed according to 3. According to (3).

The solubility of the alkaline water-soluble resin of the present invention in alkaline water was determined by conducting a solubility test as described below, and the solubility of the alkaline water-soluble resin of the present invention in alkaline water and the weight loss rate were determined. Stipulated. The solubility of the alkaline water-soluble binder resin (b) which can be preferably used in the present invention in alkaline water is, for example, a molded product of the alkaline water-soluble binder resin (b) having a shape of 5 mm or less (for example, see Examples). Such a 3 mm pellet shape, even if it is not pelletized, it may be cut to a size of 5 mm or less.) 10 g is put into 500 g of a 0.4% by weight aqueous solution of NaOH, At 25 ° C, 24
It was determined from the reduction rate of the weight of the molded body of the binder resin dissolved in the alkaline water after stirring for a time. That is, if there was any resin remaining without being dissolved after stirring for 24 hours, the resin was filtered, washed with water, and the weight after drying was determined. Then, before being subjected to the above-described solubility test, the reduction rate from the weight of the original alkaline water-soluble binder resin (b) was calculated and obtained.
That is, the ratio was determined by the ratio of <original weight−weight after solubility test> / <original weight> in%.

[Production Example 1] A water-absorbent resin (a) was prepared by the following method. That is, thermometer and blade (stirring blade)
And a 1.5-L capacity table-top jacketed kneader lined with ethylene trifluoride on the inner surface was used as a reactor, and methoxypolyethylene glycol methacrylate (molecular weight 512) 50.50 was added to the reactor.
g, methacrylic acid (molecular weight 86.09) 4.30 g, sodium methacrylate (molecular weight 108) 220.00
g, 1.4 g of polyethylene glycol diacrylate as a crosslinking agent, and 340.000 ion-exchanged water as a solvent.
05 g was charged. The proportion of the crosslinking agent in the monomer component is 0.13 mol%.

By flowing warm water of 50 ° C. through the jacket, the above aqueous solution is stirred under a stream of nitrogen gas for 50 hours.
Heated to ° C. Next, 2,2′-azobis- (2-amidinopropane) dihydrochloride (molecular weight 2
71.27, Chemical product V-50 manufactured by Wako Pure Chemical Industries, Ltd.)
Was added and stirred for 10 seconds, then the stirring was stopped and the mixture was allowed to stand. The ratio of the polymerization initiator to the monomer component is 0.2 mol%.

The polymerization reaction was started immediately after the addition of the polymerization initiator, and the internal temperature reached 100 ° C. (peak temperature) after 95 minutes. Thereafter, the contents were aged for 30 minutes while flowing warm water of 80 ° C. through the jacket. Thus, a hydrogel was obtained. After completion of the reaction, the hydrogel was disintegrated by rotating a blade until the hydrogel became fine, and then the hydrogel was taken out by inverting the reactor.

The obtained hydrogel was dried at 140 ° C. for 3 hours using a hot air circulation type drier. After drying, the dried product was pulverized using a desktop simple pulverizer (manufactured by Kyoritsu Riko Co., Ltd.). Thus, a water-absorbent resin (1) having an average particle size of 180 μm was obtained.

[Production Example 2] An alkaline water-soluble binder resin (b) was prepared by the following method.

That is, a capacity 5 having a thermometer and a dropping device
In a 0 L tank reactor, 0.40 kg of acrylic acid, 2.45 kg of ethyl acrylate, 0.15 kg of methyl methacrylate
kg, 2,2′-azobis- (2,4
10 g of dimethylvaleronitrile) and 3 kg of methyl alcohol as a solvent. Also, 0.93 kg of acrylic acid and 2.2 parts of methyl acrylate were added to the dropping device.
2 kg, methyl methacrylate 3.85 kg, 2,2'-
Azobis- (2,4-dimethylvaleronitrile) 23
g and 7 kg of methyl alcohol.

The above-mentioned methyl alcohol solution was heated to 65 ° C. with stirring in a nitrogen gas atmosphere, and reacted for 20 minutes. Thereby, the polymerization rate of the content was adjusted to 72%. Subsequently, while maintaining the internal temperature at 65 ° C., the above mixed solution was dropped uniformly from the dropping device over 2 hours. After completion of the dropwise addition, the content was aged at 65 ° C. for another 3 hours. After completion of the reaction, the content was mixed with 10 kg of methyl alcohol to obtain 33% by weight of the alkali water-soluble resin (1).
A methyl alcohol solution was obtained.

The obtained alkaline water-soluble binder resin (1) has a weight average molecular weight of 140,000 and an acid value of 104.
mg KOH / g. As a result of performing differential scanning calorimetry on the alkaline water-soluble binder resin (1), the alkaline water-soluble binder resin (1) had two glass transition temperatures in the range of -80 ° C to 120 ° C. . The obtained methyl alcohol solution of the alkaline water-soluble binder resin (1) was further desolvated using a twin-screw extruder to obtain cylindrical pellets having a diameter of 3 mm and a length of 3 mm. 10 g of the pellets were added at room temperature to 500 g of a 0.4% by weight aqueous sodium hydroxide solution in a beaker.
After stirring with a magnetic stirrer, the mixture completely dissolved after 4 hours.

[Production Example 3] An alkaline water-soluble binder resin (b) was prepared by the following method. That is, 0.473 kg of acrylic acid and 1.725 k of methyl acrylate were placed in a 50 L capacity tank reactor equipped with a thermometer and a dropping device.
g, 2.45 kg of ethyl acrylate, 2.85 kg of methyl methacrylate, 33 g of 2,2′-azobis- (2,4-dimethylvaleronitrile) as a polymerization initiator, and 15 kg of methyl alcohol as a solvent. .

The above methyl alcohol solution was heated to 65 ° C. with stirring in a nitrogen gas atmosphere, and reacted for 5 hours. Thus, a 33% by weight methyl alcohol solution of the alkaline water-soluble binder resin (2) was obtained. The weight average molecular weight of the obtained alkaline water-soluble binder resin (2) was 100,000 and the acid value was 46 mgKOH / g. [Example 1] The water-absorbent resin (1) 50 produced in Production Example 1
15 parts by weight of a 33% by weight methyl alcohol solution 15 of the alkaline water-soluble binder resin (1) produced in Production Example 2
By mixing and dispersing with 0 parts by weight, a paint (1) for a friction reducing agent according to the present invention was obtained. Then, the obtained paint (1) for a friction reducing agent was applied with a thickness of 1 mm, a diameter of 50 mm,
The surface (both inside and outside) of a steel pipe having a length of 500 mm was uniformly brushed so as to have a dry thickness of 200 μm.
After 1 hour of natural drying, the coating has sufficient strength,
Even when strongly rubbed with an iron spatula, it did not peel off easily.

The steel pipe coated with the friction reducing agent paint (1) thus obtained was first immersed in ion-exchanged water for 10 minutes. The surface of the steel pipe after immersion was covered with the water absorbing and swollen friction reducing agent layer and was slimy.

Next, this steel pipe is erected vertically on the ground on the premises of our company (Suita City, Osaka Prefecture), and has a thickness of 3 mm and 6 mm on the steel pipe.
A steel pipe of 0 mm × 60 mm was placed on the steel pipe, and a steel pipe was poured into the soil by hitting it 10 times from a height of 60 cm with a 500 g hammer. Table 1 shows the depth cast from the ground at this time. The steel pipe was left for one day, and the next day, about 500 ml of ion-exchanged water was first applied to the surface (both inside and outside) of the steel pipe, and left for about 10 minutes. The steel pipe surface after standing was covered with the water absorbing and swollen friction reducing agent layer and was slimy. Next, a steel pipe was poured into the soil in the same manner as on the first day.
At this time, the depth of the casting from the surface is shown in Table 1. Further, the steel pipe was allowed to stand for one day, and was driven by the same operation as on the second day. The depth of the steel pipe from the ground surface is shown in Table 1.

In the above experiment, the depth cast from the ground surface over the three days was significantly larger than that without the application of the friction reducing agent paint 1, and the depth hardly changed over the three days. From these results, it can be seen that by applying the friction reducing agent coating material (1) of the present invention to the substrate surface, the friction reducing agent layer is supplied to the substrate surface over three days, and the friction reducing effect is exhibited. You can see that it was done.

Example 2 The same operation as in Example 1 was carried out except that the applied thickness (when dried) of the coating material for the friction reducing agent was 300 μm, and the depth that was cast for 3 days at that time was used. Table 1
It was shown to.

In the above experiment, the depth cast from the ground surface over the three days was significantly larger than that without the application of the friction-reducing agent paint (1), and the depth hardly changed over the three days. . Looking at this result,
Similarly to the result of Example 1, by applying the friction-reducing agent coating material (1) of the present invention to the substrate surface, the friction-reducing agent layer is supplied to the substrate surface over three days, and the friction-reducing effect is obtained. It can be seen that was exhibited.

[Embodiment 3] In the embodiment 1, the production example 2
Production Example 3 using the same amount instead of the friction-reducing agent paint (1) using the alkali water-soluble binder resin (1) obtained in
Except for using the friction reducing agent paint (2) using the alkali water-soluble binder resin (2) obtained in the above, the same operation was carried out.
It was shown to.

In the above experiment, the depth cast from the ground surface over the three days was significantly larger than that without the application of the friction reducing agent paint (2), and the depth was hardly changed during the three days. . Looking at this result,
Similarly to the results of Examples 1 and 2, by applying the friction-reducing agent coating material (2) of the present invention to the substrate surface, the friction-reducing agent layer was supplied to the substrate surface over three days, and the friction was reduced. It can be seen that the reduction effect was exhibited.

Comparative Example 1 The same operation as in Example 1 was carried out except that the paint (1) for a friction reducing agent was not applied.
Table 1 shows the depth of the casting for three days.

In the above experiment, the depth cast from the ground surface over the three days was significantly smaller than that obtained by applying the friction reducing agent paint (1). From the results, it is significantly different from Examples 1 to 3, and when the paint (1) for a friction reducing agent of the present invention was not used at all, the efficiency of the operation of placing the base material was extremely low. It turns out that it becomes.

Comparative Example 2 The procedure of Example 1 was repeated except that grease (manufactured by Showa Shell Sekiyu KK) was applied in a thickness of 200 μm instead of applying the friction reducing agent coating material 1 in a thickness of 200 μm. Performed the same operation, and Table 1 shows the depths cast for three days.

In the above experiment, the depth of the ground surface was almost the same as that obtained by applying the friction reducing agent paint (1) on the first day, but was 1 day on the second and third days. It was remarkably smaller than the day, and was almost the same as that without any coating. As can be seen from these results, when grease is applied, the friction reduction effect is temporary without any sustained release, and is significantly different from Examples 1 to 3, and it is apparent from the second day and thereafter. Shows that almost no friction reducing agent effect appears.

[0093]

[Table 1]

[0094]

EFFECTS OF THE INVENTION Negative friction cut method when burying underground structures in soil, latent box method when burying various tanks and water tanks in the ground, and various fume pipes,
When a steel pipe, a steel pipe pile, etc. are buried (horizontally and vertically) underground for a propulsion method or the like, the water-absorbent resin (a) of the present invention, which is a specific coating composition, and an alkaline water-soluble binder resin (b) (Or a binder resin (d) having an acid value of 40 to 500 mgKOH / g) and a coating material for a friction reducing agent containing a solvent (c) as essential components, using various types of substructures (H steel, steel sheet pile, concrete) Piles, steel pipe piles, etc.), various tanks, water tanks, fume pipes, steel pipes, etc.

Thus, for example, in the case of the negative friction cut method, a necessary portion (friction reducing layer portion) does not peel off at the time of embedding regardless of the method at the time of embedding, and after a certain period of time, water in the soil is absorbed. By doing so, the coating film swells for a long time after embedding, and by supplying the friction reducing agent layer between the base material and the ground, the substructure can be protected from ground changes such as land subsidence.

In the case of the submersion method or the propulsion method, water is absorbed from the soil throughout the construction period, so that the space between the surface of the base material and the soil when buried in the ground is gradually released. By supplying a friction-reducing agent layer, friction can be reduced and embedding can be facilitated (speed-up of embedding, reduction of pushing force at the time of embedding, etc.).

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification code FI C10M 107/38 C10M 107/38 107/42 107/42 107/46 107/46 111/04 111/04 E02D 5/28 E02D 5 / 28 5/60 5/60 27/18 27/18 E21D 9/06 301 E21D 9/06 301L 311 311Z // C10N 20:00 C10N 20:00 Z 40:00 40:00 Z 50:02 50:02 (58) Field surveyed (Int. Cl. ⁷ , DB name) C09D 5/00

Claims (5)

(57) [Claims] 1. A water-absorbent resin (a) having an acid value of 40 to 500 m
g KOH / g and is a binder resin (d) and a solvent (c) a friction modifier coating material as essential components, wherein
Paint for friction reducer is negative friction cut
By being applied to the surface of the <br/> base material used in burying method of repeatedly hitting set law or substrate, friction modifier layer to reduce friction between the substrate surface and the ground (soil) Form
Wherein the friction-reducing agent layer is
A coating for a friction-reducing agent, which is supplied in a sustained release manner between the coating composition and the soil . 2. The coating material for a friction reducing agent according to claim 1, wherein the water-absorbent resin (a) is a salt-resistant water-absorbent resin. 3. A negative friction cutting method for an underground substructure using the paint for a friction reducing agent according to claim 1 or 2 . 4. A latent box construction method using the paint for a friction reducing agent according to claim 1 or 2 . 5. A propulsion method comprising using the paint for a friction reducing agent according to claim 1 or 2 .