Polymeric foaming agent with maximum orientation density and preparation method and application thereof

Abstract

The application discloses a polymeric foaming agent with maximum orientation density and a preparation method and application thereof, and belongs to the technical field of earth pressure balance shield construction materials. The polymeric foaming agent with maximum orientation density comprises the following components in percentage by mass: 3-6% of an anionic surfactant, 4-12% of a nonionic surfactant, 0.5-1% of a foam stabilizer and 0.5-1% of an additive, and the balance is water. The nonionic surfactant molecules are neutral in the solution, the nonionic surfactant and the anionic surfactant are prepared according to a certain proportion in the application, the neutral nonionic surfactant fills the larger gap between the anionic surfactants, and the problems of small orientation density, poor uniformity and stability and the like of the existing foaming agent can be effectively solved, the polymeric foaming agent has good foaming ratio, half-life and supporting force, and the on-site slag soil improvement effect can be effectively improved.

Description

Technical Field

[0001] This invention belongs to the technical field of earth pressure balance shield tunneling materials, specifically relating to a polymeric foaming agent with maximized orientation density, its preparation method, and its application. Background Technology

[0002] Shield tunneling, with its advantages of safety, efficiency, and wide adaptability, has been widely used in rail transit construction. Among these, earth pressure balance shield tunneling, due to its broad adaptability to various geological formations and strong rock-breaking capabilities, has become the preferred method for shield tunneling under various complex geological conditions. When constructing in clay strata or mudstone strata with high clay mineral content, the high cohesion of the soil causes the excavated clay to easily adhere to the cutterhead and cutterhead. Under high temperature and pressure, this easily forms hard mud cakes that clog the soil chamber and screw conveyor, leading to difficulties in slag removal. In water-rich sandy strata, the high water content often leads to frequent blowouts. To ensure smooth and sustainable construction, it is necessary to improve the excavated soil to give it good fluidity and support properties. Current technology mainly involves injecting chemical modifiers such as foaming agents into the front of the cutterhead and the soil chamber. Existing foaming agents mainly consist of anionic surfactants. Surfactants have an amphoteric molecular structure: one end is a hydrophilic group, and the other end is a hydrophobic group; they can oriented on the surface of the solution. Due to the mutual repulsion between charges, foaming agents have low orientation density and poor uniformity and stability. Summary of the Invention

[0003] To address the aforementioned problems, this invention provides a polymeric foaming agent with maximized alignment density, its preparation method, and its application. Due to the repulsive forces between the negative charges of anionic surfactant molecules, large gaps exist when anionic surfactant molecules are oriented on the surface of a solution. Foaming agents using only anionic surfactants have poor adaptability to changes in temperature, moisture content, or acidity / alkalinity due to these gaps, and cannot effectively improve the fluidity of construction waste. The polymeric foaming agent provided by this invention consists of anionic surfactants, nonionic surfactants, foam stabilizers, and additives. Nonionic surfactant molecules are neutral in solution. By mixing nonionic and anionic surfactants in a certain proportion, the neutral nonionic surfactant fills the large gaps between the anionic surfactants, effectively solving the problems of low alignment density, poor uniformity, and poor stability in existing foaming agents. It exhibits better foaming ratio, half-life, and supporting force, and can effectively improve the on-site improvement effect of construction waste.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] One of the technical solutions of the present invention is to provide a polymeric foaming agent with maximized alignment density, wherein the components, by mass percentage, include: 3-6% anionic surfactant, 4-12% nonionic surfactant, 0.5-1% foam stabilizer and 0.5-1% additives, with the balance being water.

[0006] Preferably, the polymeric foaming agent with maximized alignment density comprises, by mass percentage: 3-5% anionic surfactant, 4-10% nonionic surfactant, 0.5-1% foam stabilizer, and 0.5-1% additives, with the balance being water.

[0007] Preferably, the polymeric foaming agent with maximized alignment density comprises, by mass percentage: 4% anionic surfactant, 8% nonionic surfactant, 0.5% foam stabilizer, 0.5% additives, and the balance water; or, 6% anionic surfactant, 9% nonionic surfactant, 1% foam stabilizer, 0.5% additives, and the balance water; or, 5% anionic surfactant, 5% nonionic surfactant, 1% foam stabilizer, 0.5% additives, and the balance water.

[0008] Foaming agents with the above composition have particularly good stability, resulting in lower tunneling torque in shield tunneling projects. They can also effectively improve the fluidity and plasticity of the excavated soil, ensuring the sustainability of construction.

[0009] Preferably, the anionic surfactant is a sulfonate-type anionic surfactant.

[0010] More preferably, the sulfonate-type anionic surfactant is one or more of sodium alkylbenzene sulfonate, fatty acid sulfonyl ester, and alkylnaphthalene sulfonate. Sodium alkylbenzene sulfonate is most preferred, as it is one of the most important types of anionic surfactants, exhibiting good foaming power, foam stability, and chemical stability, and is readily available with low production costs.

[0011] Preferably, the nonionic surfactant is one or a mixture of stearyl alcohol, nonylphenol, and lauroyl diethanolamine.

[0012] The nonionic surfactant of this invention is not easily affected by the presence of strong electrolytes, nor by acids or alkalis. It can be mixed with other types of surfactants, has good compatibility, good solubility in various solvents, does not undergo strong adsorption on solid surfaces, and has good emulsifying, wetting, and dispersing abilities as well as strong stability.

[0013] Preferably, the foam stabilizer is one or a mixture of polyacrylamide, polyvinyl alcohol, and silicone polyether emulsion.

[0014] The main function of the foam stabilizer in this invention is to control the structural stability of the bubble liquid film, so that the surfactant molecules are distributed in an orderly manner in the bubble liquid film, giving the foam good elasticity and self-healing ability.

[0015] Preferably, the additive is sodium docosyl diphenyl ether disulfonate.

[0016] The additives selected in this invention have multiple functions such as toughening, acid and alkali resistance, oxidation resistance, and extended service life.

[0017] The second technical solution of the present invention provides a method for preparing a polymeric foaming agent with maximized alignment density, comprising the following steps:

[0018] Mix the anionic surfactant and nonionic surfactant evenly, add them to water at 50-60℃ and stir until completely dissolved. After cooling, add the foam stabilizer and additives, stir evenly, and let stand to defoam, thus completing the preparation.

[0019] Preferably, the stirring rate is 900-1200 rpm; the settling and defoaming time is 80 min.

[0020] The third technical solution of the present invention is to provide an application of the above-mentioned polymeric foaming agent with maximized alignment density in shield tunneling in clay strata.

[0021] The beneficial technical effects of the present invention are as follows:

[0022] The polymeric foaming agent provided by this invention has strong adaptability. The nonionic surfactant used is not easily affected by the presence of strong electrolytes, nor by acids or alkalis. It can be mixed with other types of surfactants, has good compatibility, good solubility in various solvents, does not undergo strong adsorption on solid surfaces, has good lubrication and dispersion capabilities, and strong stability. It lubricates clay lumps, reduces surface tension, and has strong penetration ability. It has a good dispersion effect on clay lumps, which can significantly reduce the risk of clogging and improve slag discharge efficiency.

[0023] The polymeric foaming agent provided by this invention has strong support. The reasonable configuration of nonionic and anionic surfactants makes the surfactant molecules of the foaming agent arranged tightly and evenly, which greatly enhances the support of the foaming agent.

[0024] The polymeric foaming agent provided by this invention has good stability. The maximization of the alignment density and the addition of foam stabilizers and additives give the foaming agent good elasticity and structural stability, preventing the effective components from failing during the soil improvement process. Its effective action time and dispersion effect are excellent.

[0025] The polymeric foaming agent provided by this invention has good stability after dissolution of each component, does not produce precipitation during storage, and is non-toxic and harmless, and will not affect the soil and groundwater in the construction area. Attached Figure Description

[0026] Figure 1 This is a comparison diagram of the molecular arrangement structure of surfactants in polymeric foaming agents and ordinary foaming agents.

[0027] Figure 2 The diagram shows the molecular structures of nonionic and anionic surfactants; where 1 is a nonionic surfactant molecule, 2 is an anionic surfactant molecule, 3 is a hydrophilic group, and 4 is a hydrophobic group. Detailed Implementation

[0028] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0029] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, are also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0030] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar to or equivalent to those described herein may be used in the implementation or testing of this invention.

[0031] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0032] Example 1

[0033] To prepare 1000g of a polymeric foam agent with maximized alignment density, the weights of each component are as follows:

[0034] Anionic surfactant (sodium dodecylbenzenesulfonate): 40g

[0035] Nonionic surfactant (stearyl alcohol): 80g

[0036] Foam stabilizer (polyvinyl alcohol): 5g

[0037] Additive (sodium docosyl diphenyl ether disulfonate): 5g

[0038] Water: 870g

[0039] The preparation steps of the above foaming agent are as follows:

[0040] 1) Mix 40g of anionic surfactant and 80g of nonionic surfactant evenly. Stir water at 50-60℃ in a mixing tank at 900rpm. Add the evenly mixed surfactant to the water in batches until completely dissolved.

[0041] 2) Transfer the solution prepared above to room temperature. When the temperature gradually decreases to room temperature (around 25°C), slowly add 5g of foam stabilizer and 5g of sodium dodecyl diphenyl ether disulfonate, and stir until completely dissolved.

[0042] 3) The foaming agent was prepared by standing for 80 minutes. No turbidity or precipitation was observed after standing at room temperature for 30 days.

[0043] Example 2

[0044] To prepare 1000g of a polymeric foam agent with maximized alignment density, the weights of each component are as follows:

[0045] Anionic surfactant (sodium dodecylbenzenesulfonate): 60g

[0046] Nonionic surfactant (stearyl alcohol): 90g

[0047] Foam stabilizer (polyvinyl alcohol): 10g

[0048] Additive (sodium docosyl diphenyl ether disulfonate): 5g

[0049] Water: 835g

[0050] The preparation steps of the above foaming agent are as follows:

[0051] 1) Mix 60g of anionic surfactant and 90g of nonionic surfactant evenly. Stir water at 50-60℃ in a mixing tank at 1000rpm. Add the evenly mixed surfactant to the water in batches until completely dissolved.

[0052] 2) Transfer the solution prepared above to room temperature. When the temperature gradually decreases to room temperature (around 25°C), slowly add 10g of foam stabilizer and 5g of sodium dodecyl diphenyl ether disulfonate to it and stir until completely dissolved.

[0053] 3) The foaming agent was prepared by standing for 80 minutes. No turbidity or precipitation was observed after standing at room temperature for 30 days.

[0054] Example 3

[0055] To prepare 1000g of a polymeric foam agent with maximized alignment density, the weights of each component are as follows:

[0056] Anionic surfactant (sodium dodecylbenzenesulfonate): 50g

[0057] Nonionic surfactant (stearyl alcohol): 50g

[0058] Foam stabilizer (polyvinyl alcohol): 10g

[0059] Additive (sodium docosyl diphenyl ether disulfonate): 5g

[0060] Water: 885g

[0061] The preparation steps of the above foaming agent are as follows:

[0062] 1) Mix 50g of anionic surfactant and 50g of nonionic surfactant evenly. Stir water at 50-60℃ in a mixing tank at 1200rpm. Add the evenly mixed surfactant to the water in batches until completely dissolved.

[0063] 2) Transfer the solution prepared above to room temperature. When the temperature gradually decreases to room temperature (around 25°C), slowly add 10g of foam stabilizer and 5g of sodium dodecyl diphenyl ether disulfonate to it and stir until completely dissolved.

[0064] 3) The foaming agent was prepared by standing for 80 minutes. No turbidity or precipitation was observed after standing at room temperature for 30 days.

[0065] Comparative Example 1

[0066] Compared to Example 2, the only difference is that silicone oil was chosen as the foam stabilizer instead of polyvinyl alcohol.

[0067] The prepared foaming agent showed some turbidity and sedimentation after standing at room temperature for 30 days.

[0068] Comparative Example 2

[0069] Compared to Example 2, the only difference is that sodium hexadecyl acrylate was chosen as an additive instead of sodium dodecyl diphenyl ether disulfonate.

[0070] Compared to Example 2, the half-life of the foaming agent was reduced from 15 min to 13 min, a reduction of about 15%.

[0071] Comparative Example 3

[0072] Compared with Example 2, the only difference is that anionic surfactants are used exclusively (the mass of which is the sum of the masses of the two surfactants in Example 2), and no nonionic surfactants are added.

[0073] In comparative example 3, the foaming agent exhibited significant clay clumps on the cutterhead surface and inside the soil chamber during actual engineering applications, resulting in a marked increase in cutterhead torque. In contrast, the foaming agent prepared in example 2 produced only a small amount of clay clumps during construction, leading to a more than twofold increase in tunneling efficiency.

[0074] Figure 1 This image shows a comparison of the molecular arrangement structures of surfactants in polymeric foaming agents and ordinary foaming agents. The left image shows the molecular arrangement structure of surfactants in polymeric foaming agents, and the right image shows the molecular arrangement structure of surfactants in ordinary foaming agents.

[0075] Figure 2 The diagram shows the molecular structures of nonionic and anionic surfactants; where 1 is a nonionic surfactant molecule, 2 is an anionic surfactant molecule, 3 is a hydrophilic group, and 4 is a hydrophobic group.

[0076] The actual field application effects of the foaming agents prepared in Examples 1-3 and Comparative Examples 1-3:

[0077] The different foaming agents prepared in Examples 1-3 and Comparative Examples 1-3 were all applied in the Xinjiang EH Engineering shield tunneling project. Examples 1-3 showed significant dispersion during use, with no mud cake formation or clogging. The tunneling torques were 1695 kN.m, 1565 kN.m, and 1870 kN.m, respectively. Lower torque indicates less adhesion of clay to the cutterhead and tools, resulting in a more pronounced dispersion effect of the foaming agent. Comparative Example 1 did not add a foam stabilizer, so some turbidity and sedimentation appeared after 30 days on-site. Comparative Example 2 did not add sodium dodecyl diphenyl ether disulfonate, and its foaming agent half-life was 13 min, compared to 15 min in Example 2. Comparative Example 3 did not add a nonionic surfactant, resulting in increased clay clumping during actual application. Compared to Example 2, the support force decreased by 50%, and the cutterhead torque increased from 1565 kN.m to 2300 kN.m.

[0078] Based on the above results, it can be seen that the ratio of the components of the foaming agent in this invention has a significant impact on the dispersion and stability of this invention. The absence of some components will prevent the clay from clumping, reduce the torque of the cutter head, and improve the stability of the foaming agent.

[0079] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. An alignment density maximized polymeric foaming agent, characterized by, The components of the polymeric foam agent with maximum orientation density are, by mass percentage, anionic surfactant 3-6%, non-ionic surfactant 4-12%, foam stabilizer 0.5-1% and auxiliary agent 0.5-1%, with the balance being water; The anionic surfactant is sodium dodecyl benzene sulfonate; The non-ionic surfactant is stearyl alcohol; The foam stabilizer is polyvinyl alcohol; The auxiliary agent is sodium dodecane diphenyl ether disulfonate.

2. The alignment density maximized polymeric foaming agent according to claim 1, characterized in that, The components are, by mass percentage, anionic surfactant 3-5%, non-ionic surfactant 4-10%, foam stabilizer 0.5-1% and auxiliary agent 0.5-1%, with the balance being water.

3. The alignment density maximized polymeric foaming agent of claim 1, wherein, The components are, by mass percentage, anionic surfactant 4%, non-ionic surfactant 8%, foam stabilizer 0.5%, auxiliary agent 0.5% and the balance being water; or, anionic surfactant 6%, non-ionic surfactant 9%, foam stabilizer 1%, auxiliary agent 0.5% and the balance being water; or, anionic surfactant 5%, non-ionic surfactant 5%, foam stabilizer 1%, auxiliary agent 0.5% and the balance being water.

4. A process for the preparation of a polymeric foaming agent with maximum orientation density according to any one of claims 1 to 3, characterized in that, The preparation steps of the polymeric foam agent with maximum orientation density include: The anionic surfactant and the non-ionic surfactant are mixed uniformly, added to 50-60°C water and stirred until completely dissolved, and then the foam stabilizer and the auxiliary agent are added after cooling, stirred uniformly, left to stand to remove foam, and the preparation is completed.

5. Use of the polymeric foam agent with maximum orientation density according to any one of claims 1-3 in shield construction in clay strata.

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