CN110218604B

CN110218604B - Stable shield tail sealing grease and preparation method thereof

Info

Publication number: CN110218604B
Application number: CN201910552048.6A
Authority: CN
Inventors: 孔恒; 郭飞; 姜瑜; 张丽丽; 任斌; 张旭光; 尹丽艳; 徐霖; 扬伏川; 郑青; 赵晨阳; 高胜雷; 田治州; 王凯丽; 林雪冰; 王璐; 户迁迁; 杨斌; 刘雷廷; 李振坤
Original assignee: Beijing Chaoxu Dingxin Municipal Engineering Detection Technology Co ltd; Xinda Chemical Technology Co ltd; Beijing Municipal Construction Co Ltd
Current assignee: Beijing Chaoxu Dingxin Municipal Engineering Detection Technology Co ltd; Xinda Chemical Technology Co ltd; Beijing Municipal Construction Co Ltd
Priority date: 2019-06-25
Filing date: 2019-06-25
Publication date: 2022-06-17
Anticipated expiration: 2039-06-25
Also published as: CN110218604A

Abstract

The invention discloses stable shield tail sealing grease and a preparation method thereof, and belongs to the technical field of sealing materials for shield machines. The efficient and stable shield tail sealing grease adopts an LDH composite antioxidant stabilizer as an inorganic filler, and utilizes LDH intercalation assemblability to assemble a heat stabilizer and an oxidant guest molecule between LDH layers in an intercalation manner, so that the defects of poor oxidation resistance and poor storage stability of the sealing grease are overcome. The siloxane coupling agent is introduced to eliminate the difference between organic materials and inorganic materials, improve the interaction between interfaces and improve the water-resistant strength and integrity of the sealing grease. The biomass fiber and the polymer fiber are matched for use, so that the defects that a single biological fiber does not have a lubricating function, is high in abrasion and is difficult to biodegrade are overcome. And the adopted preparation method is simple, environment-friendly and convenient for industrial production.

Description

Stable shield tail sealing grease and preparation method thereof

Technical Field

The invention relates to efficient and stable shield tail sealing grease and a preparation method thereof, and belongs to the technical field of sealing for shield machines.

Background

The shield construction method has the characteristics of high automation degree, high construction speed, safety, stability and small influence on the environment, and is increasingly adopted at home and abroad. When the shield is tunneled, the shield shell plays a role in protecting the pipe sheets, but a relative sliding process exists between the shield shell and the installed pipe sheets, and a gap exists between the shield shell and the outer wall, so that water, silt and the like outside the shield shell easily enter the shield body, and accidents such as ground subsidence, water flooding tunnels and the like are caused. Therefore, the shield shell and the segment gap must be sealed. Most shield machines adopt a shield tail sealing mode of filling sealing grease among a plurality of steel wire brushes, and during tunneling, the shield tail sealing grease is injected among the shield tail steel wire brushes through a grease injection system, and the gap between the inside of the sealing steel wire brushes and the gap between the steel wire brushes is filled by means of the extrusion force of the grease, so that the shield tail forms a firm sealing layer, and muddy water and soil sand are prevented from permeating. The sealing grease has good adhesion with the steel plate and the duct piece, and plays roles in sealing, friction reduction and corrosion prevention.

The shield machine is expensive in manufacturing cost and complex in technology, so that the requirement on sealing grease is high, and imported products produced by companies such as French CONDAT, Degussa-Admix-tures inc and Mitsubishi business are monopolized at present. The development in China is slow, the products are not uniform, and particularly the water pressure resistance sealing performance and the pumping performance are far lower than those of similar products abroad. Meanwhile, the influence of the shield machine and the shield construction stratum and the environment temperature is large, and the underground water and the soil are damaged. Chinese patent CN106244299a discloses a shield tail sealing grease, and an adhesion promoter is introduced in the invention, so that the interaction force with the surface of a base material is effectively improved, and the adhesion capability and stability of the product are enhanced. However, the compatibility between the inorganic filler and the organic matter is poor, the water pressure resistance and the sealing performance of the inorganic filler are still poor, and the water flush loss is high. Chinese patent CN107384526A discloses a shield tail sealing grease, which introduces a sheet as a leakage-proof agent to improve the water resistance, but the size of the sheet is difficult to control, and the abrasion of the sheet to a sealing grease pump is increased due to the overlarge size of the sheet. In addition, the shield tail sealing grease is extremely susceptible to thermal oxidative aging degradation, and loses the service performance.

Layered Double Hydroxides (LDH) are widely used anionic inorganic functional materials and are formed by orderly arranging two-dimensional laminates and interlayer anions. Because the LDH has the characteristics of composition and structure controllability and interlayer anion exchangeability, various functional objects can be inserted into LDH layers by using an intercalation assembly means to obtain the supermolecule nano material with different functions, such as selective ultraviolet barrier materials, selective infrared absorption materials, thermal stability, environment-friendly catalysts, flame retardants, sterilization mildewproof agents and the like.

The invention prepares the LDH composite antioxidant stabilizer with a supermolecular intercalation structure by intercalating and assembling functional guest molecules with thermal stability and oxidation resistance between LDH layers. The LDH composite antioxidant stabilizer is used as an inorganic filler and added into the shield tail sealing grease, LDH has a large amount of-OH and is thermally decomposed to absorb heat, so that the thermal decomposition and combustion rate of the sealing grease are greatly reduced, LDH is covered on the surface of the sealing grease after being thermally decomposed, and then the entry of heat energy and oxygen is cut off to form a carbon layer protective film, so that the thermal stability of the sealing grease at a high-temperature section is improved. By means of the supermolecule interaction between interlayer object molecules (an antioxidant and a heat stabilizer) and an LDH (layered double hydroxide) host layer plate, the host layer plate has a protection effect on the interlayer objects, and the barrier effect of an inorganic layer plate lamellar structure can greatly improve the stability, reduce the external migration of the object molecules and improve the durability of performance. In addition, the siloxane coupling agent is introduced to improve the compatibility of organic components (fibers, thickening agents, preservatives and the like) and inorganic main agent fillers (LDH composite antioxidant stabilizers, bentonite and the like) in the sealing grease, eliminate the difference between organic materials and inorganic materials, improve the interaction between interfaces, improve the dispersibility and adhesive force of the inorganic fillers in organic matters, and improve the water-resistant strength and integrity of the sealing grease. LDH is also called hydrotalcite, is a nano-level supermolecule layered structure, has small particle size, can obviously improve the lubricating property and the pumping property of sealing grease, can form a compact sealing layer during compression sealing, and shows excellent sealing performance. The invention adopts the matching use of the biomass fiber and the polymer fiber, and improves the defects that the single biological fiber has no lubrication function, higher abrasion and the single polymer fiber is difficult to biodegrade.

Disclosure of Invention

The invention aims to provide efficient and stable shield tail sealing grease and a preparation method thereof. The shield tail sealing grease has good storage stability, water pressure sealing resistance, pumpability, oxidation resistance and mechanical properties.

The invention is realized by the following technical scheme:

a stable shield tail sealing grease is prepared from the following raw materials in parts by weight: 10-20 parts of base oil, 7-15 parts of thickening agent, 0.2-2 parts of preservative, 15-30 parts of inorganic filler, 2-5 parts of bentonite, 5-25 parts of composite fiber, 0.1-1 part of siloxane coupling agent and 2-7 parts of lubricant.

The base oil is one or more of mechanical hydraulic oil, isooctanol modified rapeseed oil, isooctanol modified soybean oil, epoxidized soybean oil or mineral oil.

The thickening agent is one or more of rosin resin, polyacrylamide, polymethacrylate, polyisobutylene or C5 resin, and polyisobutylene is preferred.

The preservative is one or more of benzimidazole, organic sulfur or organic ammonium, and organic sulfur is preferred.

The inorganic filler is one or more of calcium carbonate, limestone, barium sulfate, mica powder or hydrotalcite powder, preferably hydrotalcite powder, especially LDH composite material, and can be one or more of LDH composite flame retardant, LDH composite antioxidant stabilizer and LDH composite heat stabilizer by inserting different functional objects, and further preferably LDH composite antioxidant stabilizer.

The bentonite is one or more of sodium bentonite, calcium bentonite, potassium bentonite or organic bentonite, and preferably sodium bentonite.

The composite fiber is a composite of biological fiber and polymer fiber, and the composite fiber has a net structure and can reduce abrasion to the grease pump. The biological fiber is one or more of wood fiber, cotton fiber and flax fiber, preferably cotton fiber. The polymer fiber is one or more of polypropylene fiber, polyester fiber and polypropylene fiber, and preferably polyester fiber.

The siloxane coupling agent is one or more of gamma-glycidoxypropyltrimethoxysilane, gamma-aminopropyltriethoxysilane, gamma- (methacryloyloxy) propyltrimethoxysilane and N- (beta-aminoethyl) -gamma-aminopropyltrimethoxysilane, and preferably gamma-glycidoxypropyltrimethoxysilane.

The lubricant is one or more of lithium grease, calcium grease, mixed soap grease, carbamido grease or aluminum-based composite grease, and preferably lithium grease.

A method for preparing stable shield tail sealing grease comprises the following specific preparation steps: step A: the LDH composite antioxidant stabilizer is prepared by adopting a coprecipitation method. Will contain M²⁺、M³⁺The nitrate of (A) is formulated into a mixed salt solution, M²⁺Is divalent metal ion Mg²⁺、Zn²⁺、Ni²⁺、Ca²⁺、Fe²⁺Or Cu²⁺Either or both, preferably Mg²⁺Or Zn²⁺；M³⁺Is trivalent metal ion Al³⁺、Co³⁺、Ti³⁺、Fe³⁺Or Cr³⁺Any one or two of them, preferably Al³⁺；

And B: preparing an alkali solution with the molar concentration of 0.05-2mol/L, wherein the alkali solution is NaOH, KOH or an ammonia solution;

and C: preparing antioxidant active component (AO) and heat stable component (MO) into mixed solution with certain concentration, wherein the amount of AO and MO is M³⁺The amount of the substance is 0.5-10 times. The antioxidant active ingredient (AO) for intercalation is an organic acid containing a hindered phenol group or phosphite group or its sodium salt, preferably a hindered phenolate salt. The thermally stable active component (MO) used for intercalation is a metal mixture, 2-ethylhexanoate, stearate, phenylate, phenoxide, preferably stearate.

Step D: and D, dropwise adding the alkali solution prepared in the step B into the mixed salt solution prepared in the step A and the mixed solution prepared in the step C, stirring for 2-10 hours under the protection of nitrogen, performing centrifugal separation and washing on reaction products circularly until the pH value of the mother solution is 7-8, and performing vacuum drying on a filter cake for 12-24 hours to obtain the LDH composite antioxidant stabilizer with the supramolecular structure.

And E, step E: mixing a siloxane coupling agent, base oil, an inorganic filler and a thickening agent in a reaction kettle according to corresponding weight parts, and reacting for 2-4 hours at 100 ℃ until the thickening agent is completely dissolved;

step F: sequentially adding bentonite, a preservative and a lubricant according to the corresponding weight parts, stirring at a constant temperature (25-50 ℃) until the components are uniformly mixed, finally adding composite fibers, keeping the temperature and continuously stirring for 2-4 hours to obtain the pasty shield tail sealing grease.

Compared with the prior art, the efficient and stable shield tail sealing grease and the preparation method thereof have the following advantages: according to the invention, LDH intercalation assembly is utilized to intercalate and assemble the heat stabilizer and oxidant object molecules between LDH layers, so that the defects of poor oxidation resistance and poor storage stability of the sealing grease are overcome. The siloxane coupling agent is introduced to eliminate the difference between organic materials and inorganic materials, improve the interaction between interfaces and improve the water-resistant strength and integrity of the sealing grease. The small particle size (50-500nm) of LDH obviously improves the lubricity and the pumpability of the sealing grease, and overcomes the defect of large abrasion of a grease pump. The biomass fiber and the polymer fiber are matched for use, so that the defects that a single biological fiber does not have a lubricating function, is high in abrasion and is difficult to biodegrade are overcome. And the adopted preparation method is simple, environment-friendly and convenient for industrial production.

Drawings

FIG. 1 is a graph of pumpability versus aging time for example 1 and comparative examples 1-5.

FIG. 2 is a graph of water-flush vectors as a function of aging time for example 1 and comparative examples 1-5.

Detailed Description

The present invention is further illustrated by the following examples.

Example 1

Step a: 2.46kg of Mg (NO) are weighed out₃)₂·6H₂O and 1.72kg Al (NO)₃)₃·9H₂Dissolving O in 60L of ionized water to prepare a mixed salt solution.

Step b: 1.44kg NaOH was weighed out and dissolved in 160L deionized water to make an alkali solution.

Step c: 2.5kg of beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid and 2.5kg of sodium stearate were weighed into 100L of deionized water.

Step d: and c, mixing the solutions prepared in the steps a and c, dropwise adding the alkali solution prepared in the step b into the mixed solution of the step a and the step c under the protection of nitrogen and stirring, controlling the pH value to be 9 after dropwise addition within 30min, reacting for 24h at room temperature under the protection of nitrogen, performing 6 filtration and washing cycles, and finally drying the filter cake in vacuum for 24h to obtain the LDH composite antioxidant stabilizer.

Step e: 0.5g of gamma-glycidoxypropyltrimethoxysilane, 15kg of base oil 150SN mineral oil, 20kg of inorganic filler LDH composite antioxidant stabilizer and 9kg of thickening agent polyisobutene are mixed in a reaction kettle and react for 3 hours at 100 ℃ until the thickening agent is completely dissolved;

step f: then sequentially adding 5kg of sodium bentonite, 1kg of preservative benzimidazole and 5kg of lubricating oil lithium-based lubricating grease, stirring at constant temperature until the mixture is uniformly mixed, finally adding 20kg of composite fiber (cotton fiber and polyester fiber composite), keeping the temperature and continuously stirring for 4 hours to obtain the white pasty shield tail sealing grease.

Comparative example 1

The comparative example provides a shield tail sealing grease preparation method, which has the steps basically the same as those of example 1, except that: 20kg of calcium carbonate is used as an inorganic filler to replace an LDH composite antioxidant stabilizer.

Comparative example 2

The comparative example provides a shield tail sealing grease preparation method, which has the steps basically the same as those of example 1, except that: 10kg of LDH composite antioxidant stabilizer is added as inorganic filler.

Comparative example 3

The comparative example provides a shield tail sealing grease preparation method, which has the steps basically the same as those of example 1, except that: 40kg of LDH composite antioxidant stabilizer is added as inorganic filler.

Comparative example 4

The comparative example provides a shield tail sealing grease preparation method, which has the steps basically the same as those of example 1, except that: 60kg of LDH composite antioxidant stabilizer is added as inorganic filler.

Comparative example 5

The comparative example provides a shield tail sealing grease preparation method, which has the steps basically the same as those of example 1, except that: 20kg of cotton fibers were used instead of the composite fibers of cotton fibers and polyester fibers.

The same procedure was used for the performance tests of inventive example 1 and comparative examples 1 to 5: the pumpability was tested using ASTM D1092, the hydraulic seal resistance was tested using Malsumara, the water-jet vector was tested using ASTM D4049, the metal corrosion was tested using ASTM D4048, and the test results are as follows:

table 1 shows the results of the performance tests of example 1 of the present invention and comparative examples 1 to 5.

As can be seen from Table 1, the LDH composite antioxidant stabilizer can remarkably improve the pumping property, the water pressure resistant sealing property and the water-washing vector of the sealing grease. The composite fiber replaces cotton fiber, so that the pumping performance and the water-flushing vector of the sealing grease can be obviously improved.

Fig. 1 and 2 are change curves of the pumpability and the water flush vector of the shield tail seal grease with the increase of the aging time, and it can be known from the graphs that the pumpability and the water flush vector of the seal grease without the addition of the LDH composite antioxidant stabilizer (comparative example 1) are significantly reduced after the shield tail seal grease is stored for 12 months, which shows that the LDH composite antioxidant stabilizer can improve the storage stability of the shield tail seal grease.

Example 2

Step a: 6.4kg Mg (NO) are weighed out₃)₂·6H₂O、7.4kg Zn(NO₃)₂·6H₂O and 3.9kg Al (NO)₃)₃·9H₂Dissolving O in 60L of ionized water to prepare a mixed salt solution.

Step b: 15kg of NaOH is weighed and dissolved in 180L of deionized water to prepare an alkali solution.

Step c: 15kg of 2, 8-di-tert-butyl-4-methylphenol and 20kg of sodium stearate were weighed into 100L of deionized water.

Step e: 0.8g of gamma-glycidoxypropyltrimethoxysilane, 15kg of base oil 150SN mineral oil, 20kg of inorganic filler LDH composite antioxidant stabilizer and 9kg of thickening agent polyisobutene are mixed in a reaction kettle and react for 3 hours at 100 ℃ until the thickening agent is completely dissolved;

step f: then sequentially adding 5kg of sodium bentonite, 1kg of preservative and 5kg of lubricating oil, stirring at constant temperature until the mixture is uniformly mixed, finally adding 20kg of composite fiber, keeping the temperature and continuously stirring for 4 hours to obtain the pasty shield tail sealing grease.

Example 3

Step e: mixing 0.5g of gamma- (methacryloyloxy) propyl trimethoxy silane, 17kg of base oil epoxidized soybean oil, 22kg of inorganic filler LDH composite antioxidant stabilizer and 10kg of thickening agent polyisobutylene in a reaction kettle, and reacting for 3 hours at 100 ℃ until the thickening agent is completely dissolved;

step f: then sequentially adding 6kg of calcium bentonite, 1kg of preservative benzimidazole and 5kg of lubricating oil lithium-based lubricating grease, stirring at constant temperature until the materials are uniformly mixed, finally adding 20kg of composite fiber (cotton fiber and polyester fiber composite), keeping the temperature, and continuously stirring for 4 hours to obtain the white pasty shield tail sealing grease.

Example 4

A, step a: 6.4kg Mg (NO) are weighed out₃)₂·6H₂O and 7.4kg Al (NO)₃)₃·9H₂Dissolving O in 60L of ionized water to prepare a mixed salt solution.

Step c: 15kg of 2, 8-di-tert-butyl-4-methylphenol and 20kg of 2-sodium ethylhexanoate were weighed and added to 100L of deionized water.

Step e: mixing 0.6g of gamma-aminopropyltriethoxysilane, 17kg of base oil isooctanol modified rapeseed oil, 22kg of inorganic filler LDH composite antioxidant stabilizer and 10kg of thickening agent polyisobutene in a reaction kettle, and reacting for 3 hours at 100 ℃ until the thickening agent is completely dissolved;

step f: then sequentially adding 6kg of organic bentonite, 1kg of preservative benzimidazole and 5kg of lubricating oil lithium-based lubricating grease, stirring at constant temperature until the mixture is uniformly mixed, finally adding 20kg of composite fiber (cotton fiber and polyester fiber composite), keeping the temperature and continuously stirring for 4 hours to obtain the white pasty shield tail sealing grease.

Table 2 shows the results of the performance tests of examples 2 to 4 of the present invention.

Item	Test standard	Example 2	Example 3	Example 4
					Pumpability (25 ℃, 1MPa, g/min)	ASTM D1092	42	40	45
Sealing property against water pressure (25 ℃,3.5MPa)	Malsumara	Water-tight	Water leakage-proof device	Water leakage-proof device
					Water flush vector (0.28MPa,5min,/%)	ASTM D4049	0	0	0
Corrosiveness of Metal (copper sheet, 100 ℃, 24h)	ASTM D4048	No corrosion	No corrosion	No corrosion

The technical principle of the present invention has been described above with reference to specific embodiments, which are merely preferred embodiments of the present invention. The protection scope of the present invention is not limited to the above embodiments, and all technical solutions belonging to the idea of the present invention belong to the protection scope of the present invention. Other embodiments of the invention will occur to those skilled in the art without the exercise of inventive faculty, and such will fall within the scope of the invention.

Claims

1. A stable shield tail sealing grease is prepared from the following raw materials in parts by weight: 10-20 parts of base oil, 7-15 parts of thickening agent, 0.2-2 parts of preservative, 15-30 parts of inorganic filler, 2-5 parts of bentonite, 5-25 parts of composite fiber, 0.1-1 part of siloxane coupling agent and 2-7 parts of lubricant;

the base oil is one or more of mechanical hydraulic oil, isooctanol modified rapeseed oil, isooctanol modified soybean oil, epoxidized soybean oil or mineral oil;

the thickening agent is one or more of rosin resin, polyacrylamide, polymethacrylate, polyisobutylene or C5 resin;

the preservative is one or more of benzimidazole, organic sulfur or organic ammonium;

the inorganic filler is hydrotalcite powder LDHs, is prepared by inserting various functional objects into LDH layers by an intercalation assembly means, and is one or more of LDH composite flame retardant, LDH composite antioxidant stabilizer and LDH composite heat stabilizer;

the bentonite is one or more of sodium bentonite, calcium bentonite, potassium bentonite or organic bentonite;

the composite fiber is a composite of biological fiber and polymer fiber, has a net structure, and can reduce the abrasion to the grease pump; the biological fiber is one or more of wood fiber, cotton fiber and flax fiber; the polymer fiber is one or more of polypropylene fiber, polyester fiber and polypropylene fiber;

the siloxane coupling agent is one or more of gamma-glycidoxypropyltrimethoxysilane, gamma-aminopropyltriethoxysilane, gamma- (methacryloyloxy) propyltrimethoxysilane and N- (beta-aminoethyl) -gamma-aminopropyltrimethoxysilane.

2. A stable type shield tail sealing grease according to claim 1, wherein the lubricant is one or more of lithium-based grease, calcium-based grease, mixed soap-based grease, urea-based grease or aluminum-based composite grease.

3. The preparation method of the stable shield tail sealing grease according to claim 1, which is characterized by comprising the following specific preparation steps: step A: preparing an LDH composite antioxidant stabilizer by adopting a coprecipitation method; will contain M²⁺、M³⁺The nitrate of (A) is formulated into a mixed salt solution, M²⁺Is divalent metal ion Mg²⁺、Zn²⁺、Ni²⁺、Ca²⁺、Fe²⁺Or Cu²⁺Either one or both of; m³⁺Is trivalent metal ion Al³⁺、Co³⁺、Ti³⁺、Fe³⁺Or Cr³⁺Either one or both of them;

and C: preparing a mixed solution of an antioxidant active component AO and a heat-stable component MO at a certain concentration, wherein the amount of AO and MO is M³⁺0.5-10 times of the amount of the substance;

step D: dropwise adding the alkali solution prepared in the step B into the mixed salt solution prepared in the step A and the mixed solution prepared in the step C, stirring for 2-10 hours under the protection of nitrogen, performing centrifugal separation and washing on reaction products to circularly wash until the pH value of the mother solution is 7-8, and performing vacuum drying on a filter cake for 12-24 hours to obtain the LDH composite antioxidant stabilizer with the supramolecular structure;

step E: mixing a siloxane coupling agent, base oil, an inorganic filler and a thickening agent in a reaction kettle according to corresponding weight parts, and reacting for 2-4 hours at 100 ℃ until the thickening agent is completely dissolved;

step F: sequentially adding bentonite, a preservative and a lubricant according to the corresponding weight parts, stirring at a constant temperature of 25-50 ℃ until the mixture is uniform, finally adding composite fibers, keeping the temperature and continuing stirring for 2-4 hours to obtain paste shield tail sealing grease;

the antioxidant active component AO used for intercalation is organic acid or sodium salt thereof containing hindered phenol group or phosphite group; the thermally stable active component MO used for intercalation is a metal mixture, a salt of 2-ethylhexanoic acid, stearic acid, a salt of phenyl acid or a salt of phenolic acid.