Phosphorus-free normal-temperature low-foam degreasing agent and degreasing process

Abstract

The invention discloses a non-phosphorus normal-temperature low-foam degreasing agent, which is prepared from the following effective components in percentage by weight: 15 to 35 percent of caustic alkali compound, 0.8 to 3.6 percent of sodium carbonate, 0.6 to 2.5 percent of sodium metasilicate pentahydrate, 0.7 to 3.5 percent of sodium citrate dehydrate, 7.0 to 16.0 percent of sodium gluconate, 0.2 to 0.7 percent of sodium formate, 6.5 to 7.2 percent of organic solvent, 0.1 to 0.9 percent of emulsifier and 8.7 to 14.6 percent of surfactant. The invention further discloses a degreasing process which comprises the following steps: diluting the normal-temperature low-foam degreasing agent with desalted water, and applying the diluted normal-temperature low-foam degreasing agent to the surface of strip steel for degreasing.

Description

Technical Field

[0001] This invention relates to a degreasing agent and a degreasing process, and more particularly to a degreasing agent and a degreasing process for cold-rolled strip steel. Background Technology

[0002] During the rolling and other production processes, cold-rolled strip steel comes into contact with various oily substances. Under the intense friction between the rolls and the strip, a large amount of iron powder is generated on both the roll and strip surfaces. Some of this iron powder adheres to the strip surface. Simultaneously, the deformation zone of the strip generates significant heat, causing the cold rolling fluid to demulsify and form an oil film on the roll and strip surfaces, thus providing lubrication. However, some of the grease adheres to the strip surface, forming a stubborn contaminant along with dust and iron powder on the high-temperature surface. Furthermore, during storage and transportation, the strip surface also carries rust-preventive oil and dust contaminants.

[0003] Therefore, strip steel must be degreased before annealing, especially before coating or surface treatment. The degree of degreasing directly affects the quality of subsequent processing. When the surface of cold-rolled strip steel containing rolling oil, machine oil, powder, and dust is not thoroughly cleaned, these contaminants will turn into carbides after annealing. Carbides not only detract from the appearance but also become a potential source of surface defects in subsequent processes. In particular, for coated products, they can affect the adhesion of the coating, causing uneven surface layers and reduced corrosion resistance.

[0004] For the reasons mentioned above, degreasing is crucial in the surface treatment process of metal materials. Currently, the most widely used degreasing method in steel mills is alkaline solution degreasing. The degreasing agent needs to be heated to a high temperature, with existing cleaning operations generally reaching above 70°C. This high-temperature degreasing method not only consumes a large amount of energy and increases production costs, but also causes significant air pollution due to the rapid evaporation of the alkaline solution, which is extremely detrimental to environmental protection.

[0005] Furthermore, degreasing agents generate a large amount of foam during use, sometimes even overflowing the tank, posing significant production safety hazards and deteriorating the working environment. Moreover, the large amount of foam can carry away some of the degreasing agent, increasing consumption and causing waste. To reduce foam generation, defoamers are often added during production. This not only increases production costs but also means that some defoamer components can adhere to the steel plate surface, leading to serious consequences such as poor coating.

[0006] Meanwhile, conventional degreasing agents require the addition of phosphates as the main cleaning aid, and phosphates have the characteristics of high solubility, good cleaning properties, and low cost. However, the discharge of phosphorus-containing wastewater is harmful to the environment and requires treatment before discharge, which increases the cost and energy consumption of wastewater treatment. Summary of the Invention

[0007] One of the objectives of this invention is to provide a phosphorus-free, room-temperature, low-foaming degreasing agent. This degreasing agent is formulated with the premise of reducing environmental pollution, and none of its components contain heavy metals or phosphorus. Through the compounding of various additives such as surfactants, inorganic salts, and organic compounds in appropriate proportions, a synergistic effect is generated, achieving a highly efficient and low-foaming room-temperature degreasing effect.

[0008] To achieve the above objectives, the present invention provides a phosphorus-free, room-temperature, low-foaming degreasing agent, the effective components of which include:

[0009] Caustic alkali compounds: 15–35 wt%.

[0010] Sodium carbonate: 0.8–3.6 wt%.

[0011] Sodium metasilicate pentahydrate: 0.6–2.5 wt%.

[0012] Sodium citrate dihydrate: 0.7–3.5 wt%.

[0013] Sodium gluconate: 7.0–16.0 wt%.

[0014] Sodium formate: 0.2–0.7 wt%.

[0015] Organic solvent: 6.5–7.2 wt%.

[0016] Emulsifier: 0.1–0.9 wt%.

[0017] Surfactant: 8.7–14.6 wt%.

[0018] Furthermore, in the phosphorus-free, room-temperature, low-foaming degreasing agent described in this invention, the mass percentage of each component is as follows:

[0019] Caustic alkali compounds: 15–35 wt%.

[0020] Sodium carbonate: 0.8–3.6 wt%.

[0021] Sodium metasilicate pentahydrate: 0.6–2.5 wt%.

[0022] Sodium citrate dihydrate: 0.7–3.5 wt%.

[0023] Sodium gluconate: 7.0–16.0 wt%.

[0024] Sodium formate: 0.2–0.7 wt%.

[0025] Organic solvent: 6.5–7.2 wt%.

[0026] Emulsifier: 0.1–0.9 wt%.

[0027] Surfactant: 8.7–14.6 wt%.

[0028] The remainder is deionized water.

[0029] In this invention, the caustic alkali compound in the phosphorus-free, room-temperature, low-foaming degreasing agent serves as the main component of the degreasing agent, providing a strongly alkaline cleaning environment and increasing the conductivity during electrolytic cleaning, thereby enhancing the cleaning effect.

[0030] In some embodiments, the caustic alkali compound may include one or both of sodium hydroxide or potassium hydroxide.

[0031] In this invention, the sodium carbonate in the phosphorus-free, room-temperature, low-foaming degreasing agent undergoes hydrolysis in the aqueous solution, which can make the aqueous solution alkaline and thus play a role in aiding cleaning.

[0032] In this invention, sodium metasilicate pentahydrate in the phosphorus-free, room-temperature, low-foaming degreasing agent can adjust and stabilize the alkalinity of the solution, and has good suspension and dispersion capabilities for dirt.

[0033] In the phosphorus-free, room-temperature, low-foaming degreasing agent of this invention, sodium citrate dihydrate, sodium gluconate, and sodium formate are compounded, exhibiting excellent coordination ability with calcium and magnesium ions. Through chelation, they can remove dust and iron powder firmly adhering to the surface of steel strips, preventing secondary pollution and enhancing decontamination capabilities. Simultaneously, sodium citrate dihydrate and sodium gluconate not only have scale-inhibiting functions but also rust-preventing effects.

[0034] In this invention, the organic solvent in the phosphorus-free, room-temperature, low-foaming degreaser can reduce foam stability by lowering the surface tension of water, which helps to suppress foam formation. It can also affect the flowability and viscosity of the degreaser, further reducing the rate of foam formation and increasing the foam's ruptureability.

[0035] In this invention, the emulsifier in the phosphorus-free, room-temperature, low-foaming degreasing agent can promote the cleaning process.

[0036] In this invention, the surfactant in the phosphorus-free, room-temperature, low-foaming degreaser is an important additive in the degreaser. The lipophilic groups in the surfactant molecules can interact with the oil stains, and through the penetration and encapsulation effect, the emulsified oil film is separated from the surface of the strip steel, thereby achieving the purpose of removing the oil stains.

[0037] The phosphorus-free, room-temperature, low-foaming degreasing agent of this invention, through the combined effects of wetting, emulsification, dispersion, and solubilization, allows its highly penetrating additives to effectively penetrate to the microscopic surface of metal, reducing the viscosity of oil stains, shortening wetting time, and achieving effective removal of grease and dirt. Simultaneously, the degreasing agent can also form water-soluble substances with the metal ions in the oil stains, thereby removing oil stains and dust and other impurities adhering to the oil stains from the strip surface, preventing oil stains from re-aggregating and re-adsorbing onto the strip surface.

[0038] Furthermore, in the phosphorus-free, room-temperature, low-foaming degreasing agent of the present invention, the organic solvent is selected from at least one of butanediol and ethanol.

[0039] In this invention, butanediol and ethanol are used as organic solvents in the phosphorus-free, room-temperature, low-foaming degreasing agent. This can reduce foam stability by lowering the surface tension of water, which helps to inhibit foam formation. It can also affect the flowability and viscosity of the degreasing agent, further reducing the speed of foam formation and increasing the foam's ruptureability.

[0040] Furthermore, in the phosphorus-free, room-temperature, low-foaming degreasing agent of the present invention, when the organic solvent is selected from butanediol and ethanol, its mass percentage content satisfies: butanediol 1.2-5.0%, ethanol 1.5-6.0%.

[0041] Furthermore, in the phosphorus-free, room-temperature, low-foaming degreasing agent of the present invention, the emulsifier includes erucamide.

[0042] In this invention, the erucic acid amide in the phosphorus-free, room-temperature, low-foaming degreasing agent has an emulsifying effect, which helps to emulsify the oil and water phases to form a stable emulsion and promotes the cleaning process.

[0043] Furthermore, in the phosphorus-free, room-temperature, low-foaming degreasing agent of the present invention, the surfactant is selected from at least one of: octylphenol polyoxyethylene ether, isooctyl alcohol polyoxyethylene ether, isodecyl alcohol polyoxyethylene ether, and lauryl alcohol polyoxyethylene ether.

[0044] In this embodiment, by optimizing the ratio of various surfactants, the compound surfactants have high wettability and low foaming properties. By reducing surface free energy and surface tension, they enhance emulsification, dispersion and other effects, thereby improving the overall cleaning efficiency and low foaming properties.

[0045] Furthermore, in the phosphorus-free, room-temperature, low-foaming degreasing agent of the present invention, the surfactant comprises: 2.3-6.9 wt% octylphenol polyoxyethylene ether, 1.6-5.8 wt% isooctyl alcohol polyoxyethylene ether, 0.3-3.6 wt% isodecyl alcohol polyoxyethylene ether, and 0.3-3.9 wt% lauryl alcohol polyoxyethylene ether.

[0046] Another objective of this invention is to provide a degreasing process suitable for room-temperature, low-foaming degreasing agents and production processes in cold-rolled strip steel production lines. This process can be used in the degreasing process of cold-rolled strip steel after cold rolling in steel mills, eliminating the need for consuming large amounts of energy to heat the degreasing agent and preventing significant evaporation of alkaline solutions. Furthermore, the process maintains a low foam level, eliminating the need for defoamers and avoiding the problem of excessive foam removal of some of the effective components of the degreasing agent. In addition, since the degreasing agent is phosphorus-free, it reduces the pressure on wastewater treatment, saving on wastewater treatment costs and energy consumption.

[0047] To achieve the above objectives, the present invention provides a degreasing process in which the above-mentioned phosphorus-free room temperature low foaming degreasing agent is diluted with desalinated water and applied to the surface of the strip steel for degreasing.

[0048] Furthermore, in the degreasing process described in this invention, the phosphorus-free, room-temperature, low-foaming degreasing agent is diluted 8 to 20 times with desalinated water.

[0049] Furthermore, in the degreasing process described in this invention, the degreasing temperature is 10–50°C, and the chemical degreasing time is 2–10 seconds.

[0050] Furthermore, in the degreasing process described in this invention, the electrolysis time is 0.2–0.9 s, and the current density is 10–25 A / dm³. 2 .

[0051] Compared with existing technologies, the phosphorus-free, room-temperature, low-foaming degreasing agent and degreasing process for cold-rolled strip steel described in this invention have the following advantages and beneficial effects:

[0052] The room-temperature low-foaming degreasing agent of the present invention achieves a synergistic effect by compounding various additives in appropriate proportions, thereby achieving a highly efficient and low-foaming room-temperature degreasing effect.

[0053] The degreasing process described in this invention prevents foam from overflowing the tank during degreasing, eliminating the need for defoamers; after degreasing, the surface reflectivity of the strip is >90%, and the residual oil content on the strip surface is <10mg / m². 2 It fully meets the needs of production and use.

[0054] The room-temperature low-foaming degreasing agent and its production process described in this invention can be used in the degreasing process of cold-rolled strip steel after cold rolling. It eliminates the need for consuming large amounts of energy to heat the degreasing agent and prevents significant alkali evaporation. Simultaneously, the process maintains a low foam level, eliminating the need for defoamers and avoiding the problem of excessive foam carrying away some of the effective components of the degreasing agent. This significantly reduces production costs and improves the working environment. Furthermore, the degreasing agent is phosphorus-free, meeting environmental protection requirements, reducing the pressure on wastewater treatment, and saving on wastewater treatment costs and energy consumption. It is suitable for the fast production pace of strip steel and has a strong decontamination effect on hardened steel sheets with different types of oil contamination. After degreasing, the strip steel surface has a high degree of cleanliness, fully meeting the requirements for strip steel production. Detailed Implementation

[0055] The following will further explain and illustrate the phosphorus-free, room-temperature, low-foaming degreasing agent and degreasing process described in this invention with reference to specific embodiments. However, this explanation and illustration do not constitute an undue limitation on the technical solution of this invention.

[0056] Examples 1-6

[0057] Prepare the degreasing agent according to the component ratio shown in Table 1, and stir thoroughly to dissolve it completely. In some embodiments, the stirring can be carried out for 30 to 90 minutes, and the stirring speed can be 100 to 300 r / min to obtain a phosphorus-free room temperature low-foaming degreasing agent.

[0058] A phosphorus-free, room-temperature, low-foaming degreasing agent is diluted 8-20 times with demineralized water and then applied to the surface of the steel strip for degreasing. In some embodiments, the degreasing temperature can be controlled at 10-50°C, the degreasing time at 2-10 seconds, the electrolysis time at 0.2-0.9 seconds, and the current density at 10-25 A / dm³. 2 .

[0059] Table 2 lists the specific process parameters for the degreasing process in Examples 1-6.

[0060] Tables 1-1 and 1-2 list the chemical composition of the phosphorus-free, room-temperature, low-foaming degreasing agents of Examples 1-6 of the present invention.

[0061] Table 1-1. (wt%, balance is deionized water)

[0062]

[0063] Table 1-2. (wt%, balance is deionized water)

[0064]

[0065] Note: The emulsifiers in the table above can be erucamide or oleamide.

[0066] Table 2 lists the phosphorus-free, room-temperature, low-foaming degreasing agents of Examples 1-6 of the present invention and the process parameters in the degreasing process.

[0067] Table 2.

[0068]

[0069]

[0070] Samples of cold-rolled strip steel from Examples 1-6 after the degreasing process were taken, and the degreasing effect was tested. The test results are recorded in Table 3. Among them:

[0071] Strip surface reflectance: The reflectance of the strip surface after degreasing is measured using a reflectance meter.

[0072] Residual oil content on strip surface: The residual oil content on the strip surface after degreasing is determined using a residual carbon analyzer.

[0073] Table 3 lists the degreasing effects of Examples 1-6 of the present invention.

[0074] Table 3.

[0075] serial number Steel strip surface reflectivity (%) <![CDATA[Residual oil content on strip surface (mg / m 2 )]]> Example 1 93 8.8 Example 2 96 7.9 Example 3 94 8.3 Example 4 94 8.2 Example 5 96 7.4 Example 6 95 7.5

[0076] As can be seen from Table 3 above, after degreasing using the phosphorus-free, room-temperature, low-foaming degreasing agent and degreasing process described in this invention, the surface reflectivity of the strip steel is >90%, and the residual oil content on the strip steel surface is <10mg / m². 2 It fully meets the needs of production and use.

[0077] It should be noted that the combination of the technical features in this case is not limited to the combination methods described in the claims of this case or the combination methods described in the specific embodiments. All technical features described in this case can be freely combined or combined in any way, unless they contradict each other.

[0078] It should also be noted that the embodiments listed above are merely specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and similar changes or modifications made thereto are those that can be directly derived or easily conceived by those skilled in the art from the content disclosed in the present invention, and should all fall within the protection scope of the present invention.

Claims

1. A phosphorus-free, room-temperature, low-foaming degreasing agent, characterized in that, Its active ingredients include: Caustic alkali compounds: 15–35 wt%. Sodium carbonate: 0.8–3.6 wt%. Sodium metasilicate pentahydrate: 0.6–2.5 wt%. Sodium citrate dihydrate: 0.7–3.5 wt%. Sodium gluconate: 7.0–16.0 wt%. Sodium formate: 0.2–0.7 wt%. Organic solvent: 6.5–7.2 wt%. Emulsifier: 0.1–0.9 wt%. Surfactant: 8.7–14.6 wt%.

2. The phosphorus-free, room-temperature, low-foaming degreasing agent as described in claim 1, characterized in that, The mass percentage of each component is as follows: Caustic alkali compounds: 15–35 wt%. Sodium carbonate: 0.8–3.6 wt%. Sodium metasilicate pentahydrate: 0.6–2.5 wt%. Sodium citrate dihydrate: 0.7–3.5 wt%. Sodium gluconate: 7.0–16.0 wt%. Sodium formate: 0.2–0.7 wt%. Organic solvent: 6.5–7.2 wt%. Emulsifier: 0.1–0.9 wt%. Surfactant: 8.7–14.6 wt%. The remainder is deionized water.

3. The phosphorus-free, room-temperature, low-foaming degreasing agent as described in claim 1 or 2, characterized in that, The organic solvent is selected from at least one of butanediol and ethanol.

4. The phosphorus-free, room-temperature, low-foaming degreasing agent as described in claim 3, characterized in that, When the organic solvent is selected from butanediol and ethanol, its mass percentage content satisfies the following: butanediol 1.2-5.0%, ethanol 1.5-6.0%.

5. The phosphorus-free, room-temperature, low-foaming degreasing agent as described in claim 1 or 2, characterized in that, The emulsifier includes erucamide.

6. The phosphorus-free, room-temperature, low-foaming degreasing agent as described in claim 1 or 2, characterized in that, The surfactant is selected from at least one of octylphenol polyoxyethylene ether, isooctyl alcohol polyoxyethylene ether, isodecyl alcohol polyoxyethylene ether, and lauryl alcohol polyoxyethylene ether.

7. The phosphorus-free, room-temperature, low-foaming degreasing agent as described in claim 6, characterized in that, The surfactants include: 2.3-6.9 wt% octylphenol polyoxyethylene ether, 1.6-5.8 wt% isooctyl alcohol polyoxyethylene ether, 0.3-3.6 wt% isodecyl alcohol polyoxyethylene ether, and 0.3-3.9 wt% lauryl alcohol polyoxyethylene ether.

8. A degreasing process, characterized in that, The phosphorus-free, room-temperature, low-foaming degreasing agent as described in any one of claims 1-7 is diluted with demineralized water and applied to the surface of the steel strip for degreasing.

9. The degreasing process as described in claim 8, characterized in that, Dilute the phosphorus-free, room-temperature, low-foaming degreasing agent 8 to 20 times with desalinated water.

10. The degreasing process as described in claim 8, characterized in that, The degreasing temperature is 10–50℃, the chemical degreasing time is 2–10 s, the electrolysis time is 0.2–0.9 s, and the current density is 10–25 A / dm³. 2 .

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