JP2006036827A - Lubricant composition for water-expansible sealant - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lubricant composition applied to the surface of a water-expansible sealant to be used sandwiched between concrete segments used in underground sewer construction and the like. <P>SOLUTION: The lubricant composition for a water-expansible sealant comprises a water soluble surfactant and a fatty acid amide represented by general formula (1) or general formula (2) added in an amount of 0.1-5.0 wt%. In general formula (1), R<SP>1</SP>is an 8-22C saturated fatty acid, unsaturated fatty acid or hydroxy fatty acid; and R<SP>2</SP>is hydrogen or an 8-22C alkyl group, alkenyl group or cycloalkyl-substituted alkyl group. In general formula (2), R<SP>3</SP>is an 8-22C saturated fatty acid, unsaturated fatty acid or hydroxy fatty acid; and R<SP>4</SP>denotes -(CH<SB>2</SB>)<SB>n</SB>-, wherein n denotes an integer of 1-8. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a lubricant composition applied to a surface for a water-expandable sealing material that is used by being sandwiched between concrete segments used in underground pipe construction work or the like.

  Conventionally, shield construction has been carried out to connect underground segments by connecting segments made of precast concrete. The segments are connected to adjacent segments by joint members such as bolts / nuts or lock pins. In the construction of underground pipe construction, in order to prevent the underground water from entering the tunnel, a long rubber elastic sealing material is sandwiched between the connected segments, and the elastic repulsive force of the sealing material Water is stopped. At this time, in order to effectively prevent water leakage between the segments, it is necessary to assemble the segments precisely so that there is no gap between the segments. Since the segment is heavy, if the segment is moved to adjust the fastening position after temporarily installing the segment, the lower sealant is moved while receiving the weight of the segment. A large frictional force is generated. In addition, in order to form a circle by the shield method, the key-type segment (K segment), which is the final assembly member, must be pushed between the already assembled segments, and a very high frictional force is generated.

  In order to prevent the sealing material from being peeled off or damaged by the frictional force generated at this time, a lubricant is generally applied to the surface of the sealing material to reduce the frictional resistance and prevent the sealing material from being damaged. Patent Documents 1 and 2 disclose that the assembly accuracy is improved. In actual construction, the segments are assembled by applying a lubricant to the surface of the sealing material around the segment. Patent Document 1 describes the use of a water-swellable sealing material that expands by contact with water and generates an effective water-stopping effect as a sealing material between segments.

JP-A-6-193392 Japanese Patent Laid-Open No. 8-13995

  In general, the water-swellable sealing material is a polyurethane resin, a partially saponified polyvinyl acetate resin, which has a function of absorbing water and expanding into hydrophobic unvulcanized rubber such as EPDM, chloroprene rubber, natural rubber, urethane elastomer, butyl rubber, It is made by kneading a hydrophilic expansion material such as partially formalized polyvinyl alcohol resin, polyacrylic acid resin, polyalkylene glycol resin and vulcanizing rubber. When the water-expandable sealing material made in this way comes into contact with water that has permeated between the segments, the expansion material absorbs water and expands by volume, so that the entire sealing material expands, and the repulsive force between the segments is increased. Increases water-stopping effect.

  If a hydrophobic (lipophilic) lubricant is applied to the surface of the water-expandable sealing material to reduce friction during segment assembly, which is the above-mentioned drawback, the water that has penetrated between the segments will be repelled by the hydrophobicity of the lubricant. The water action prevents water from being absorbed into the expansion material, thereby suppressing water absorption and expansion of the water-expandable sealing material, resulting in a disadvantage that the water stop effect is reduced.

  On the other hand, when a hydrophilic (water-soluble) lubricant is used in order not to impede the water absorption of the water-swellable sealing material, there is no problem of a decrease in the water-stopping effect due to the water-repellent action, but the main component of the sealing material Since the rubber itself is hydrophobic, there is a problem that it is difficult to get wet with respect to the surface of the sealing material, and it is difficult to repel or form a uniform coating film. In addition, even if it can be applied, the coating is very easy to peel off and flows out from the surface of the sealing material with a little contact or moisture in the air and penetrates into the concrete of the segment. As a result, the desired lubricating action could not be obtained. Therefore, the lubricant must be reapplied just before assembly.

  On the other hand, when a solid lubricant is used as in Patent Document 2, the problems of hydrophobicity and hydrophilicity as described above can be avoided, but the water-stopping effect of the water-swellable sealing material is fundamentally reduced. This is because the fine particles of the solid lubricant are attached to the surface of the water-expandable sealing material, so that micro unevenness is formed on the surface of the sealing material, which causes so-called “interlayer leakage”.

Therefore, as a result of earnest investigation for the purpose of obtaining a lubricant that reduces the friction generated in the seal material during the assembly of the segment and does not reduce the expandability due to water absorption of the water-expandable seal material, the present invention is water-soluble. And a lubricant composition for a water-swellable sealing material in which 0.1 to 5.0% by weight of a fatty acid amide represented by the following general formula (1) or general formula (2) is added. It was.
(Wherein R ¹ is a C ₈ -C ₂₂ saturated fatty acid, unsaturated fatty acid, or hydroxy fatty acid, and R ² is hydrogen or a C ₈ -C ₂₂ alkyl group, alkenyl group, or cycloalkyl-substituted alkyl group. is there.)
(In the formula, R ³ represents a C _{8 to} C ₂₂ saturated fatty acid, unsaturated fatty acid, or hydroxy fatty acid, and R ⁴ represents — (CH ₂ ) _n —, where n represents an integer of 1 to 8. .)

  Furthermore, in the present invention, it is preferable to use alkylbenzenesulfonic acid sodium salt as the surfactant.

  The lubricant for water-expandable seal material needs to reduce the frictional resistance when assembling the segments. However, considering the waterproof effect on underground pipes, the water-stopper of the water-expandable seal material should not be impaired. There is a need. Therefore, the main component of the lubricant must be hydrophilic and water-soluble. As such a water-soluble lubricant, it is necessary to use a water-soluble surfactant.

  There are three types of surfactants, anionic, cationic and nonionic. Most anionic surfactants are viscous liquids and are therefore preferred in the present invention. Specific examples include sodium alkylbenzene sulfonates, higher alcohol sulfate sodium salts, α-olefin sulfonates, and the like. In the present invention, it can be preferably used because it is easily wettable and easily soluble in water.

  The cationic surfactant can be used in the present invention as long as it is a water-soluble alkylamine. However, chloride-type or acetate-type cationic surfactants such as acetate, ammonium chloride, pyridinium chloride, etc. It is preferable to avoid it because it contains corrosive ions.

  Nonionic surfactants include ether types such as polyoxyalkylene glycol, polyoxyethylene alkyl ether, and polyoxyethylene alkyl phenyl ether, and ester types of glycerin fatty acid ester and sorbitan fatty acid ester. Can be used.

  Among the types of nonionic surfactants described above, polyoxyalkylene glycol is excellent in shear stability against a large load and is one of the preferred water-soluble surfactants in the present invention.

  In general, these nonionic surfactants are emulsified in water. In the present invention, “water-soluble” includes an emulsified state.

  The water-soluble surfactant in the present invention is not only a single composition of the surfactant exemplified above, but also a mixture of two or more kinds, for example, a mixed system of polyoxyalkylene glycol and sodium alkylbenzene sulfonate. May be used. This is because mixing two or more types results in a water-soluble viscous liquid having both excellent lubricity against a large load and excellent wettability to rubber. Furthermore, a mixed system to which a polyhydric alcohol such as glycol or glycerin is added for viscosity adjustment can also be used.

  Since the water-soluble surfactant has low affinity for rubber, which is the main component of the water-swellable sealing material, and poor wettability, a uniform coating film cannot be formed on the surface of the sealing material. In order to solve this problem, it is necessary to provide the property that the coating film does not repel for a long time while maintaining the lubricity and water-soluble performance of the water-soluble surfactant. In order to impart such characteristics, a technique for preventing dripping by adding a thixotropic agent is employed. However, even when a conventional thixotropic agent is used, the wettability to the surface of the hydrophobic sealing material is low, and the coating film repels over time. Moreover, not only that, the lubrication performance is lowered, and it is not suitable for use as a lubricant. In the present invention, the use of fatty acid amide does not lower the lubricating performance.

In the present invention, the compound represented by the general formula (1) or the general formula (2) is used as the fatty acid amide. Specific examples of the compound represented by the general formula (1) in which R ² is hydrogen are lauric acid amide, stearic acid amide, oleic acid amide, erucic acid amide, ricinoleic acid amide, 12-hydroxystearic acid Examples include amides. Specific examples of the compound in which R ² in the formula is an alkyl group or an alkenyl group include N-isobutyl lauric acid amide, N-isobutyl stearic acid amide, N-oleyl stearic acid amide, N-oleyl oleic acid amide, N -Stearyl stearic acid amide, N-stearyl oleic acid amide, N-oleyl palmitic acid amide, N-stearyl erucic acid amide etc. can be mentioned.

Furthermore, examples of the compound represented by the general formula (1) in which R ² is a cycloalkyl-substituted alkyl group include N-cyclohexylmethyl lauric acid amide and N-cyclohexylmethyl caproic acid amide.

  Specific examples of the compound represented by the general formula (2) include N, N′-ethylenebislauric acid amide, N, N′-methylenebisstearic acid amide, N, N′-ethylenebisstearic acid amide, N, N′-ethylenebisoleic acid amide, N, N′-ethylenebisbehenic acid amide, N, N′-ethylenebis-12-hydroxystearic acid amide, N, N′-butylene bisstearic acid amide, N, N'-hexamethylene bis stearic acid amide, N, N'-hexamethylene bis oleic acid amide, etc. can be mentioned.

  The lubricant composition of the present invention can be obtained by adding one or more of these fatty acid amides in an amount of 0.1 to 5.0% by weight based on the total amount. When the addition amount is less than 0.1% by weight, the application performance and wettability to the water-expandable sealing material are not sufficient, and there is a problem that it is difficult to maintain the lubrication performance over a long period of time.

  On the other hand, if the amount of the fatty acid amide exceeds 5.0% by weight, the resulting lubricant composition becomes too hard, which makes it difficult to apply and lowers the lubricating performance.

  As described above, the main component of the lubricant composition of the present invention is one or two or more water-soluble surfactants and the fatty acid amide, and the fatty acid amide contains a small amount of hydrogenated castor oil. May be. It is also possible to add a small amount of fine silica, benzylidene sorbitol, amino acid derivative bentonite, swellable mica, etc. for improving thixotropic properties as auxiliary thickeners.

  The fatty acid amide used in the present invention is commercially available as an industrial product. There are two types of shapes, powder and paste. A paste can be added and stirred to obtain a mixture. A powder can be added and heated and stirred to obtain a mixture.

  The fatty acid amide is dispersed in the water-soluble surfactant in a uniform fine particle state by the above-described production method, and forms a fine three-dimensional network structure in which long fibers of about 0.1 microns are intertwined. Therefore, even when the segment is stored for a long period of time with high thixotropic properties and applied to the surface of the sealing material, separation of the water-soluble surfactant does not occur, and a stable gel state is maintained over time. Even if it is the surface of a property rubber, the favorable lubricant which can be stably hold | maintained is obtained.

  Further, a special feature of this aliphatic amide compound is that when a shearing force is applied, the three-dimensional network structure is broken to form secondary aggregates, and the three-dimensional network structure is not restored. For this reason, the thixotropic liquid of the aliphatic amide compound loses thixotropic properties when external energy is disabled, and remains in the original fluid liquid.

  Due to this characteristic, when the water-swellable rubber sealant is rubbed together during segment assembly, the lubricant on the surface of the lubricant of the present invention loses its three-dimensional network structure and returns to a fluid water-soluble viscous liquid.

  Therefore, the lubricant of the present invention maintains the coating film as a wet liquid lubricant for a long time without dripping after being applied to the surface of the water-expandable sealing material by brush or the like, and is thixotropic at the time of assembling the segments. Since the properties have disappeared and the lubricant has changed to flow easily, even the low water pressure groundwater that permeates between the segments after the completion of the underground dredging can be easily washed away from the surface of the water-swellable sealing material. And the expansion of the water-expandable seal material is not hindered.

Therefore, the lubricant composition for a water-expandable sealing material of the present invention imparts lubricity to the sealing material when the segments are assembled, and the sealing material does not break during the assembly. Further, the lubricant can be applied to the segment seal material in advance, and it is not necessary to apply it on site, and the process can be simplified. Furthermore, the coating film is stable over a long period of time, and does not deteriorate the water expansion performance of the water expandable sealing material.

The compounds shown in Table 1 were mixed in the amounts shown in the table to obtain a lubricant composition for a water-swellable sealing material. About each obtained composition, the thixotropy ratio in 25 degreeC was measured. However, the thixo ratio was measured by the difference in rotation of the Brookfield type rotational viscosity type. Further, after each composition was vigorously stirred, the thixo ratio was similarly measured. Moreover, each composition was apply | coated to the vertical surface and the presence or absence of sagging was confirmed. Furthermore, it apply | coated to the water expansible sealing material, and it was left to stand for 2 months, and the state of the coating film was confirmed.
The results are shown in Table 1.

  The lubricant composition of Example 1 and the lubricant composition of Comparative Example 2 were applied to the surface of the water-swellable seal material, allowed to stand for a predetermined time, and the lubrication performance was measured with the experimental apparatus shown in FIG. However, the width of the sealing material was 20 mm, the compression rate of the sealing material was 37.5%, the drawing speed was 100 mm / min, and the drawing distance was 100 mm. The sealing material was pulled out, the pulling load was measured, and the state of the sealing material was confirmed. The results are shown in Table 2.

  The water-expandable sealing material is obtained by applying the lubricant composition of Example 1 to the surface of the water-expandable sealing material, immersing the water-expandable sealing material in water, and measuring the volume change rate of the water-expandable sealing material. The water expansibility of was measured. However, what was applied to the surface of the sealing material and left for 5 days was used. Moreover, the thing which does not apply | coat a lubricant composition as a blank was measured similarly. The result is shown in FIG.

  The present invention is used as a lubricant applied to the surface of a water-swellable sealing material that is a water-stopping agent for a segment.

Diagram showing a measuring device for measuring lubrication performance Graph showing volume expansion coefficient

Explanation of symbols

1 ... Water-expandable sealing material
2 ... Pasting board

Claims (3)

A water-swellable sealing material comprising 0.1 to 5.0% by weight of a water-soluble surfactant and a fatty acid amide represented by the following general formula (1) or (2) Lubricant composition for use.
(Wherein R ¹ is a C ₈ -C ₂₂ saturated fatty acid, unsaturated fatty acid, or hydroxy fatty acid, and R ² is hydrogen or a C ₈ -C ₂₂ alkyl group, alkenyl group, or cycloalkyl-substituted alkyl group. is there.)
(In the formula, R ³ represents a C _{8 to} C ₂₂ saturated fatty acid, unsaturated fatty acid, or hydroxy fatty acid, and R ⁴ represents — (CH ₂ ) _n —, where n represents an integer of 1 to 8. .)
  2. The lubricant composition for a water-swellable sealing material according to claim 1, wherein the water-soluble surfactant is sodium alkylbenzene sulfonate.   The said water-soluble surfactant is polyoxyalkylene glycol, The lubricant composition for water-swellable sealing materials of Claim 1 characterized by the above-mentioned.