High-water-solubility steel wire drawing lubricant powder
By introducing expandable sodium polyacrylate microcapsules into the metal drawing lubricant powder to form a loose lubricating film, the problem of difficult-to-remove lubricating film is solved, thereby improving coating quality and production efficiency and reducing costs.
Patent Information
- Application Number
- CN202511517506.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-23
- Publication Date
- 2026-02-27
AI Technical Summary
Existing metal drawing lubricants contain components that are poorly soluble in water, making it difficult to completely remove the lubricating film, affecting the quality and adhesion of subsequent coatings, and increasing production costs and process complexity.
It uses a highly water-soluble steel wire drawing lubricant powder containing stearate, extreme pressure agent, rust inhibitor, lubricant, water absorbent and sodium polyacrylate expandable microcapsules. The microcapsules are vaporized and expanded under high pressure to form a loose lubricating film, which is easy to clean.
It significantly improves the efficiency of water washing to remove lubricating film, reduces residue on steel wire surface, improves coating quality and adhesion, and reduces production costs.
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Abstract
Description
Technical Field
[0001] This invention belongs to the technical field of additives for metal wire processing, and specifically relates to a highly water-soluble lubricating powder for steel wire drawing. Background Technology
[0002] Metal drawing lubricant is a lubricating material used in the metal wire drawing process. Its core function is to form a lubricating film between the metal wire and the drawing die, significantly reducing interfacial friction, thereby reducing energy consumption during drawing and extending the die's lifespan. However, most metal drawing lubricants contain components that are poorly soluble in water, such as metal soaps. This makes it difficult to completely remove the lubricating film remaining on the metal wire surface using conventional water washing. Such residue can seriously affect the quality and adhesion of subsequent processing steps such as plating. Therefore, in existing production processes, the drawn metal wire often needs to be repeatedly cleaned, sometimes even relying on specialized chemical cleaning agents. This not only increases the complexity of the process but also significantly raises the operating costs of the production line. Summary of the Invention
[0003] To solve the above-mentioned technical problems, the present invention provides a highly water-soluble steel wire drawing lubricating powder, the components of which, by weight, include: 45-60 parts of stearate, 2-5 parts of extreme pressure agent, 1-2 parts of rust inhibitor, 2-5 parts of lubricating aid, 1-2 parts of water absorbent, and 10-20 parts of sodium polyacrylate expandable microcapsules.
[0004] Stearates can form a low-shear-strength lubricating film on the metal surface, effectively reducing the coefficient of friction and preventing wear caused by direct contact between the metal wire and the drawing die. The stearates used here are a mixture of sodium stearate and calcium stearate in a weight ratio of 6–9:1–4. Calcium stearate, compared to sodium stearate, forms a thicker lubricating film on the steel wire surface during drawing, exhibiting good compressive strength and elongation, but its water solubility is poor and it is difficult to remove. Sodium stearate, on the other hand, has good water solubility, making it easy to clean after drawing and suitable for steel wire drawing with subsequent coating requirements. Using both in combination balances lubrication performance and subsequent cleanability, improving overall performance.
[0005] Expandable sodium polyacrylate microcapsules are microcapsules with cross-linked sodium polyacrylate and / or cross-linked sodium methacrylate as the shell and a low-boiling-point organic compound as the core, and can be prepared by the following method:
[0006] (1) Mix acrylate monomers, crosslinking agents, organic porogens and initiators in a weight ratio of 100:1~3:10~20:0.1~0.5 to form an oil phase;
[0007] Among them, the acrylate monomers are one or more of methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, and butyl methacrylate;
[0008] The crosslinking agent is one or more of ethylene glycol dimethacrylate, ethylene glycol diacrylate, and trimethylolpropane triacrylate;
[0009] The organic porogen is either n-heptane or cyclohexane. The choice is mainly based on two considerations: First, the heat generated by the intense friction between the wire and the die cavity wall during the drawing process is sufficient to vaporize and expand the organic porogen, allowing the microcapsules to function. Second, the organic porogen must remain stable at the preparation temperature (60℃~80℃) of the sodium polyacrylate expandable microcapsules to prevent it from vaporizing and escaping during polymerization, which would cause the microcapsules to fail. Therefore, n-heptane or cyclohexane was chosen.
[0010] (2) Mix deionized water and surfactant at a weight ratio of 100:1 to 4 to form an aqueous phase;
[0011] (3) The oil phase obtained in step (1) and the aqueous phase obtained in step (2) are mixed at a weight ratio of 1:3 to 6 and fully emulsified. The mixture is then transferred to a high-pressure reactor and polymerized at 60°C to 80°C for 8 to 24 hours, and then filtered.
[0012] (4) Disperse the filter cake obtained after filtration in step (3) in an aqueous sodium hydroxide solution, hydrolyze it at 60℃~80℃ for 5~10 hours, filter it, wash the obtained filter cake and dry it;
[0013] The sodium hydroxide aqueous solution has a mass concentration of 10-20%, and the mass amount of sodium hydroxide aqueous solution is 5-15 times that of the acrylate monomer in step (1).
[0014] As a preferred option, the extreme pressure agent is one or more of anhydrous borax, sodium metaborate, tungsten disulfide, and boron nitride;
[0015] As a preferred option, the rust inhibitor is one or more of sodium benzoate, sodium molybdate, and sodium chromate;
[0016] Preferably, the lubricant is one or more of graphite, polyethylene wax, and talc.
[0017] As a preferred choice, the absorbent is layered sodium disilicate.
[0018] As a preferred option, the preparation process of the high water-soluble steel wire drawing lubricant powder is as follows: after thoroughly mixing stearate, extreme pressure agent, lubricant, rust inhibitor, water absorbent, and expandable sodium polyacrylate microcapsules, the mixture is pulverized and passed through a 200-mesh sieve.
[0019] The beneficial effects of this invention are as follows: the addition of expandable sodium polyacrylate microcapsules to the drawing lubricant powder significantly improves the water washing and removal efficiency of the lubricant film on the surface of the steel wire after drawing through a unique physical mechanism. Specifically:
[0020] During the process of drawing steel wire by extruding lubricating powder through the die hole, a large amount of heat is generated by the strong relative sliding friction between the wire and the die wall, making the temperature significantly higher than the boiling point of the pore-forming agent inside the microcapsules. However, due to the high-pressure extrusion environment inside the die hole, the vaporization and expansion of the pore-forming agent is suppressed. When the drawn steel wire leaves the die hole, the microcapsules in the lubricating film layer attached to the surface of the steel wire are freed from the high-pressure extrusion environment, and the pore-forming agent inside them immediately vaporizes and expands with the help of residual heat. This expansion process makes the lubricating film layer significantly looser. In the subsequent cleaning process, water can more easily penetrate and wash away the loosened lubricating film, thereby greatly reducing the residual lubricating components on the surface of the steel wire.
[0021] Furthermore, compared to directly adding low-boiling-point organic compounds, the microcapsule structure is crucial for achieving a porous lubricating film. The lubricating film is primarily composed of low-strength, small-molecule organic compounds, which are simply stacked together. Additionally, the lubricating film softens significantly at a high temperature immediately after the wire leaves the drawing die, resulting in very low strength. If the low-boiling-point organic compounds were to vaporize directly within the lubricating film, the generated gas would easily escape, and the softened film would re-level and compact on the wire surface, preventing the formation of a stable porous structure. In contrast, this solution uses expandable microcapsules whose walls effectively encapsulate the vaporization products, eliminating concerns about the gas escaping the lubricating film. Simultaneously, the expanded microcapsule shell hardens upon cooling, locking in the expansion and creating an effective pore distribution within the lubricating film, thus achieving effective porousness.
[0022] Finally, the surface of the microcapsules was modified with sodium polyacrylate groups. This was done because sodium polyacrylate and stearate are both organic salts, which would have better dispersion compatibility and facilitate the uniform dispersion of the microcapsules in the lubricating powder. In addition, sodium polyacrylate itself has better hydrophilicity, which would also help the microcapsules and the lubricating residues they carry to detach from the steel wire surface during the cleaning process. Detailed Implementation
[0023] The preparation procedures for the sodium polyacrylate expandable microcapsules used in the following experimental examples are existing technologies. They were produced by the upstream partner according to the technical specifications required by this application (mainly including the requirements for the boiling point of the pore-forming agent inside the microcapsules and the optimization requirements for the hydrophilicity of the microcapsule surface). The specific preparation process is as follows:
[0024] (1) Mix 35 parts by weight of n-butyl acrylate, 65 parts by weight of ethyl methacrylate, 1.2 parts by weight of trimethylolpropane triacrylate, 15 parts by weight of cyclohexane, and 0.3 parts by weight of azobisisobutyronitrile at room temperature (25°C, the same below) to form an oil phase.
[0025] (2) Mix 400 parts by weight of deionized water and 5 parts by weight of sodium dodecyl sulfate at room temperature to form an aqueous phase;
[0026] (3) Under continuous stirring, the oil phase obtained in step (1) is added dropwise at a constant rate to the aqueous phase obtained in step (2). After the addition is completed in 30 minutes, the resulting mixture is transferred to a high-pressure reactor and heated to 65°C under a nitrogen protective atmosphere of 0.25 MPa. The emulsion polymerization reaction is continued for 18 hours and then filtered.
[0027] (4) After thoroughly washing the filter cake obtained in step (3) with deionized water, put it into 750 parts by weight of sodium hydroxide aqueous solution with a solute mass fraction of 15%. After continuously stirring, heat it to 65°C and continue the hydrolysis reaction for 5 hours. Then filter it. Wash the filter cake obtained in this step with pure water until the pH value of the washing solution is less than 8. Then dry it thoroughly at 60°C.
[0028] Example 1
[0029] By weight, 45 parts of sodium stearate, 15 parts of calcium stearate, 3 parts of anhydrous borax, 1 part of sodium metaborate, 1 part of sodium benzoate, 1 part of graphene, 3 parts of talc, 1.5 parts of layered sodium disilicate, and 20 parts of the above-prepared expandable sodium polyacrylate microcapsules were stirred and mixed thoroughly at 300 rpm and then pulverized to pass through a 200-mesh sieve.
[0030] Example 2
[0031] By weight, 40 parts of sodium stearate, 15 parts of calcium stearate, 2.5 parts of anhydrous borax, 1.5 parts of boron nitride, 1 part of sodium benzoate, 3 parts of talc, 1 part of layered sodium disilicate, and 15 parts of the above-prepared sodium polyacrylate expandable microcapsules were stirred and mixed thoroughly at 300 rpm and then pulverized to pass through a 200-mesh sieve.
[0032] Example 3
[0033] By weight, 30 parts of sodium stearate, 25 parts of calcium stearate, 2 parts of anhydrous borax, 1.5 parts of sodium metaborate, 1 part of sodium benzoate, 2 parts of graphene, 1 part of talc, 1 part of layered sodium disilicate, and 15 parts of the above-prepared expandable sodium polyacrylate microcapsules were stirred and mixed thoroughly at 300 rpm and then pulverized to pass through a 200-mesh sieve.
[0034] Example 4
[0035] By weight, 30 parts of sodium stearate, 20 parts of calcium stearate, 3 parts of anhydrous borax, 1 part of sodium benzoate, 1 part of graphene, 1.5 parts of talc, 1 part of layered sodium disilicate, and 12 parts of the above-prepared sodium polyacrylate expandable microcapsules were stirred and mixed thoroughly at 300 rpm and then pulverized to pass through a 200-mesh sieve.
[0036] Blank control example 1
[0037] No sodium polyacrylate expandable microcapsules were added; all other components were the same as in Example 1.
[0038] By weight, 45 parts sodium stearate, 15 parts calcium stearate, 3 parts anhydrous borax, 1 part sodium metaborate, 1 part sodium benzoate, 1 part graphene, 3 parts talc, and 1.5 parts layered disilicate are stirred and mixed thoroughly at 300 rpm and then pulverized to pass through a 200-mesh sieve.
[0039] Comparative Example 1
[0040] Replace the "sodium polyacrylate expandable microcapsules" with an equal mass of "cyclohexane", and keep all other components the same as in Example 1:
[0041] At 0℃ (below the melting point of cyclohexane, so that cyclohexane is mixed with other components in solid form, the same below), 45 parts of sodium stearate, 15 parts of calcium stearate, 3 parts of anhydrous borax, 1 part of sodium metaborate, 1 part of sodium benzoate, 1 part of graphene, 3 parts of talc, 1.5 parts of layered disilicate, and 20 parts of cyclohexane are mixed thoroughly at 300 rpm and then pulverized to pass through a 200-mesh sieve. Store at 0℃.
[0042] Blank control example 2
[0043] No sodium polyacrylate expandable microcapsules were added; all other components were the same as in Example 2.
[0044] By weight, 40 parts sodium stearate, 15 parts calcium stearate, 2.5 parts anhydrous borax, 1.5 parts boron nitride, 1 part sodium benzoate, 3 parts talc, and 1 part layered sodium disilicate are stirred and mixed thoroughly at 300 rpm and then pulverized to pass through a 200-mesh sieve.
[0045] Comparative Example 2
[0046] Replace the "sodium polyacrylate expandable microcapsules" with an equal mass of "cyclohexane", and keep all other components the same as in Example 2:
[0047] At 0℃, by weight, 40 parts sodium stearate, 15 parts calcium stearate, 2.5 parts anhydrous borax, 1.5 parts boron nitride, 1 part sodium benzoate, 3 parts talc, 1 part layered sodium disilicate, and 15 parts cyclohexane are thoroughly mixed at 300 rpm and then pulverized to pass through a 200-mesh sieve. Store at 0℃.
[0048] To systematically evaluate the performance of the lubricating powder obtained in the above embodiments, blank control examples, and comparative examples, a drawing die (tungsten carbide die, the same below) with a hole diameter of 4.6 mm was fixedly installed in the first die box of a linear wire drawing machine, a drawing die with a hole diameter of 4.1 mm was fixedly installed in the second die box, and a drawing die with a hole diameter of 3.6 mm was fixedly installed in the third die box. Simultaneously, the lubricating powder obtained in the same embodiment, blank control example, or comparative example was filled into the first, second, and third die boxes. Lubricating powder (and always keeping the lubricating powder in the mold box sufficient) is used to sequentially pass a 5mm diameter steel wire blank (60# steel) through the first mold box (and the drawing die within it), the second mold box (and the drawing die within it), and the third mold box (and the drawing die within it) to cold draw it into a high-strength steel wire with a diameter of 3.6mm. The drawing speed is controlled at 3m / min (i.e., the speed at which the steel wire leaves the third mold box). At the same time, a circulating water cooling system is used to control the temperature of the mold cavity of each drawing die to not exceed 200℃.
[0049] The steel wires leaving the third mold box are rinsed vertically downwards with sufficient room temperature water at a pressure of 0.4 MPa. The rinsing direction is perpendicular to the wire conveying direction, and the rinsing lasts for about 0.5 seconds as the wires move. After rinsing, the wires are dried in an oven, then sandblasted to remove rust. Next, they are pre-treated in a flux bath before being hot-dip galvanized at 440℃. Finally, the surface is wiped at 780℃, rinsed thoroughly with clean water, and air-dried to obtain galvanized steel wire. Five uniform segments, each 1 meter long, are cut from the galvanized steel wire. The weights of these five segments are weighed separately, and the average weight (m1) is calculated by summing the weights.
[0050] In addition, for the steel wires that have undergone drawing, washing, and sandblasting but have not been galvanized, five uniform wire segments with a length of 1 meter are cut from them. The five wire segments are weighed separately and then the average weight m0 is calculated by summing them up.
[0051] Finally, the amount of zinc coating on the galvanized steel wire was calculated by dividing the circumferential surface area of each ungalvanized steel wire segment by (m1 - m0) (2.6 mm × 3.14 × 1000 mm). The calculated zinc coating amounts for each embodiment, blank control example, and comparative embodiment are shown in Table 1.
[0052] Evaluation of the adhesion strength of the galvanized layer by winding experiment:
[0053] Wind the above 1-meter-long galvanized steel wire around an iron rod with a diameter of 1.5 cm for 5 turns and ensure it is tightly wound. The galvanized steel wire coils wound on are closely adjacent to each other without gaps, and the winding angle is close to 90°. After winding, observe whether there are signs of peeling, cracking, or falling off on the galvanized layer on the surface of the steel wire. If there are no such phenomena, it indicates that the adhesion is qualified, as shown in Table 1 specifically.
[0054] Table 1
[0055]
[0056] Judging from Table 1 above, in the blank control example and the comparative example, since sodium polyacrylate expandable microcapsules were not used to intervene in the lubricating film formed on the surface of the steel wire after drawing, it was difficult to effectively remove the lubricating film after drawing. And due to the high residual amount of the lubricating substance on the surface of the steel wire, it further affected the zinc deposition efficiency and deposition uniformity during the subsequent galvanizing process, resulting in unstable coating quality. Therefore, the steel wire products obtained in the blank control example and the comparative example are not suitable for further coating processing subsequently.
[0057] Among them, although low-boiling organic substances were introduced as gasification components in the comparative example, due to the lack of encapsulation and restraint of the microcapsules, the gas formed by gasification easily overflowed and escaped from the lubricating film layer. And the heated lubricating film was still in a softened state. After the gas escaped, it re-leveled and became dense again. Eventually, an effective porous and loose structure could not be formed, so the cleaning effect could not be effectively improved.
[0058] In addition, to further evaluate the lubricating performance of each lubricating powder, monitor the service life of the wire drawing die in the above drawing operation (taking the subsequent wire drawing die with a hole diameter of 3.6 mm as an example, setting the surface roughness of the hole wall in the die hole deformation zone to be greater than 1.6 μm as the replacement standard, and calculating based on the wire drawing die serving continuously for 12 hours per day), as shown in Table 2:
[0059] Table 2
[0060]
[0061] As shown in Table 2, compared to the traditional lubricating powder composition in the blank control example, the overall lubrication effect decreased after adding sodium polyacrylate expandable microcapsules in Examples 1 and 2, but the decrease was very limited. Specifically, the decrease in Example 1 was 3.2% ((31-30) ÷ 31), and the decrease in Example 2 was 2.8% ((36-35) ÷ 36). Compared to the contribution of sodium polyacrylate expandable microcapsules to the zinc content of the subsequent coating: the increase in zinc content in Example 1 was 22.9% ((263-214) ÷ 214), and the increase in zinc content in Example 2 was 21.2% ((240-198) ÷ 198), so the impact on the lubrication effect was much smaller.
Claims
1. A highly water-soluble lubricating powder for drawing steel wire, characterized in that: The lubricating powder comprises, by weight, 45-60 parts stearate, 2-5 parts extreme pressure agent, 1-2 parts rust inhibitor, 2-5 parts lubricating aid, 1-2 parts water absorbent, and 10-20 parts sodium polyacrylate expandable microcapsules; wherein the sodium polyacrylate expandable microcapsules are microcapsules with cross-linked sodium polyacrylate and / or cross-linked sodium methacrylate as shells and low molecular weight organic compounds with boiling points below 100°C as cores.
2. The high water-soluble steel wire drawing lubricant powder as described in claim 1, characterized in that: The sodium polyacrylate expandable microcapsules are prepared by the following method. (1) Mix acrylate monomers, crosslinking agents, organic porogens and initiators in a weight ratio of 100:1~3:10~20:0.1~0.5 to form an oil phase; (2) Mix deionized water and surfactant at a weight ratio of 100:1 to 4 to form an aqueous phase; (3) The oil phase obtained in step (1) and the aqueous phase obtained in step (2) are mixed at a weight ratio of 1:3 to 6 and fully emulsified. The mixture is then transferred to a high-pressure reactor and polymerized at 60°C to 80°C for 8 to 24 hours, and then filtered. (4) Disperse the filter cake obtained after filtration in step (3) in an aqueous sodium hydroxide solution, hydrolyze it at 60℃~80℃ for 5~10 hours, filter it, wash the obtained filter cake and dry it.
3. The high water-soluble steel wire drawing lubricant powder as described in claim 2, characterized in that: The acrylate monomers are one or more of methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, and butyl methacrylate; the crosslinking agent is one or more of ethylene glycol dimethacrylate, ethylene glycol diacrylate, and trimethylolpropane triacrylate; and the organic porogen is n-heptane or cyclohexane.
4. The high water-soluble steel wire drawing lubricant powder as described in claim 1, characterized in that: The stearate is composed of sodium stearate and calcium stearate in a weight ratio of 6-9:1-4.
5. The high water-soluble steel wire drawing lubricant powder as described in claim 1, characterized in that: The extreme pressure agent is one or more of anhydrous borax, sodium metaborate, tungsten disulfide, and boron nitride.
6. The high water-soluble steel wire drawing lubricant powder as described in claim 1, characterized in that: The rust inhibitor is one or more of sodium benzoate, sodium molybdate, and sodium chromate.
7. The high water-soluble steel wire drawing lubricant powder as described in claim 1, characterized in that: The lubricating agent is one or more of graphite, polyethylene wax, and talc.
8. The high water-soluble steel wire drawing lubricant powder as described in claim 1, characterized in that: The absorbent is layered sodium disilicate.
9. The high water-soluble steel wire drawing lubricant powder as described in claim 1, characterized in that: The preparation process of the high water-soluble steel wire drawing lubricant powder is as follows: the stearate, the extreme pressure agent, the lubricant, the rust inhibitor, the water absorbent, and the expandable sodium polyacrylate microcapsules are thoroughly mixed, pulverized, and passed through a 200-mesh sieve.