KR102554210B1 - Metal wire comprising polyer film with high strength and high lubricity and method for treating surface of metal wire - Google Patents

Abstract

The present invention relates to a metal wire rod comprising a high rigidity and high lubricity coating layer formed using a polymer type coating forming composition, and a surface treatment method for a metal wire rod for forging using the polymer type coating forming composition. Specifically, it relates to a method for surface treatment of a metal wire rod including a polymer coating layer formed using a polymeric coating forming composition and a lubricating layer for wire drawing or cold forging using the coating forming composition.

Description

Metal wire rod and metal wire surface treatment method including high rigidity and high lubricity polymer coating layer

The present invention relates to a metal wire rod comprising a high rigidity and high lubricity polymer coating layer formed using a polymer type coating forming composition and a surface treatment method for a metal wire rod for forging using the polymer type coating forming composition. Specifically, it relates to a method for surface treatment of a metal wire rod including a polymer coating layer formed using a polymeric coating forming composition and a lubricating layer for wire drawing or cold forging using the coating forming composition.

The metal wire rod is a wire rod in the form of a wire, and a wire drawing and/or forging process is applied. For metal wires, it is absolutely necessary to form and provide an appropriate lubricating film through surface treatment to prevent direct friction between the material and the mold during cold forging to prevent problems such as heat generation, mold damage, and molding abnormality. Currently, the method of forming a phosphate film as a lubricating film and forming a lubricating film of metal soap thereon is most commonly used. Phosphate coating is a coating obtained by the following reaction.

[Zinc calcium phosphate reaction and metal soap lubricating film formation reaction]

Fe + 2H ₃ PO ₄ → Fe(H ₂ PO ₄ ) ₂ + 2H ⁺ ↑ (etching reaction)

2Zn(H ₂ PO ₄ ) ₂ + Ca(H ₂ PO ₄ ) ₂ → Zn ₂ Ca(PO ₄ ) ₂ + 4H ₃ PO ₄ (film reaction)

In the zinc calcium phosphate formation reaction, a corrosion reaction proceeds on the surface of the material by the free acid in the liquid, and as a result, the chemical equilibrium is broken, causing a precipitation reaction of the zinc calcium phosphate film to form a film. The free acid consumed in this process is recovered in the process of forming a phosphate film.

The resulting zinc calcium phosphate film reacts with sodium stearate (also called Bondarubera) to produce metal soap and sodium soap as follows.

Zn ₂ Ca(PO ₄ ) ₂ + 6C ₁₇ COONa → 3Zn(C ₁₇ H ₃₅ COO) ₂ + 2Na(C ₁₇ H ₃₅ COO) ₂

The zinc calcium phosphate film thus formed has a calcium zinc phosphate layer (residual film) as the first layer, a metal soap layer (reactive film) as the second layer, and a soap layer for bathing (non-reacted layer) as the third layer. The zinc calcium phosphate layer imparts low friction, corrosion resistance, heat resistance, and adhesive carrier effect, and the metal soap layer imparts seizure resistance, low friction, and corrosion resistance. The soap layer for bathing (non-reactive layer) imparts blocking resistance, releasability, seizure resistance, and low friction properties. However, there are problems in that dust (film powder) is generated by the soap layer for bath, which is an unreacted layer, resulting in a poor working environment, contamination of forming oil, and film residue remaining in the mold, shortening the life of the mold.

Meanwhile, Korean Patent Registration No. 10-1844023 discloses a composition for forming a highly lubricating film including an ethylene acrylic acid copolymer aqueous solution, an organic rust preventive agent, an inorganic rust preventive agent, and an organic wax dispersion, and a metal surface treatment method using the same.

The present invention solves the problems of zinc calcium phosphate film and reactive metal soap lubrication, and a metal wire rod and method for surface treatment of metal wire rods including a polymer lubricating layer using a film-forming composition capable of supplying eco-friendly materials and reducing costs want to provide

In addition, the present invention is to provide a metal wire rod having a polymer lubricating layer formed thereon, which improves the working environment during forging because there is no coating powder (bonder rube residue) because there is no unreacted soap layer, and less contamination with forming oil. In addition, it has excellent lubricity and seizure resistance compared to existing reactive metal soap lubrication, enabling more complex cold forging, and providing a metal wire rod formed with a polymer film layer having moisture resistance and rust resistance equivalent to that of the existing reactive metal soap lubricating film. .

The above object is achieved by a metal wire rod including a metal wire rod, a zinc calcium phosphate coating layer formed on a surface of the metal wire rod, and a polymer coating layer formed on the zinc calcium phosphate coating layer.

Preferably, the polymer film layer may be formed using a film-forming composition including a polyvinylpyrrolidone resin having a molecular weight of 20,000 to 40,000, a modified acrylic resin, a water-soluble inorganic component, and a wax.

Also preferably, the water-soluble inorganic component may be a tungstic acid salt.

Also preferably, the film-forming composition contains 3 to 10% by weight of polyvinylpyrrolidone, 10 to 30% by weight of a modified acrylic resin, 1 to 5% by weight of a water-soluble inorganic component, 10 to 20% by weight of wax, based on the total weight of the composition. It may include 1 to 5% by weight of a rust inhibitor, 0.1 to 1% by weight of a dispersion stabilizer, and 40 to 60% by weight of pure water.

In addition, the pH of the film forming composition may be 8.5 to 9.5, and the total weight of the calcium zinc phosphate film layer and the polymer film layer may be 7 to 12 g/cm ² .

In addition, the above task may include pickling the rolled metal wire rod; forming a zinc calcium phosphate coating layer on the metal wire rod; coating a film-forming composition including a polyvinylpyrrolidone resin having a molecular weight of 20,000 to 40,000, a modified acrylic resin, a water-soluble inorganic component, and a wax on the zinc calcium phosphate film layer; and drying the coating with hot air at a temperature of 60 to 100° C. for 3 to 10 minutes or at room temperature for 3 to 5 hours to form a polymer film layer.

The metal surface treatment method according to the present invention can improve workability by minimizing powder generated during cold forging, and increase lifespan due to forging oil contamination. In addition, the metal surface treatment method according to the present invention provides lubricity and seizure resistance to the metal surface to improve cold forging workability and quality by improving metal surface scratches and mold jamming symptoms occurring during cold forging. In addition, through the surface treatment according to the present invention, it is possible to increase the shelf life of the material (product) by improving rust prevention by minimizing the penetration of moisture into the metal surface.

1 is a cross-sectional view showing the configuration of a metal wire rod having a coating film according to the present invention.
2 is a photograph showing the results of measuring the moisture resistance of the wire rod manufactured in Example 1 before and after drawing.
3 is a photograph showing the results of measuring the moisture resistance of the wire rod manufactured in Example 2 before and after drawing.

All technical terms used in the present invention, unless otherwise defined, have the following definitions and correspond to the meanings commonly understood by those of ordinary skill in the art related to the present invention. In addition, although preferred methods or samples are described in this specification, those similar or equivalent thereto are also included in the scope of the present invention.

The term "about" means a reference amount, level, value, number, frequency, percentage, dimension, size, amount, weight or length of 30, 25, 20, 15, 10, 9, 8, 7, 6, 5, means an amount, level, value, number, frequency, percentage, dimension, size, quantity, weight or length that varies by 4, 3, 2 or 1%.

Throughout this specification, unless the context requires otherwise, the terms "comprise" and "comprising" include a given step or element, or group of steps or elements, but any other step or element, or It is to be understood that steps or groups of components are not excluded.

The present invention relates to a metal wire rod including a metal wire rod, a zinc calcium phosphate film layer formed on a surface of the metal wire rod, and a polymer film layer formed on the zinc calcium phosphate layer. 1 is a cross-sectional view showing the configuration of a metal wire rod having a coating film according to the present invention.

The metal wire 11 may be steel for cold forging, for example, a wire for cold forging (CHQ wire). The metal wire rod may be subjected to an alkali degreasing process and a pickling process according to the prior art.

The zinc calcium phosphate coating layer 12 can be formed by a known method. According to one embodiment, a zinc calcium phosphate film is formed as the corrosion reaction of Fe proceeds on the surface of the wire rod by the free acid in the film solution. The zinc calcium phosphate film layer forms a chemical bond with the metal component of the metal wire rod to impart low friction, corrosion resistance, heat resistance and adhesion.

The polymer film layer 13 may be formed using a film-forming composition containing polyvinylpyrrolidone resin, modified acrylic resin, water-soluble inorganic component, wax, and anti-rust component. The polymer coating layer is physically bonded to the zinc calcium phosphate coating layer (hydrogen bonding and wedge effect) to impart releasability, low friction, corrosion resistance, seizure resistance, and corrosion resistance.

It is preferable to use a water-soluble polymer having a molecular weight of 20,000 to 40,000 as the polyvinylpyrrolidone. More preferred are polyvinylpyrrolidone homopolymers and copolymers of vinylpyrrolidone and vinylacetate. An exemplary polymer is Sokalan® K 30P (BASF SE, Germany).

The modified acrylic resin is It can be obtained by mixing ethylene acrylic acid copolymer with water in an amount of 20% by weight, swelling it by applying heat, adding an alkali component and stirring until it is transparently dispersed in water. NH ₄ OH, triethyl amine, dimethyl ethanol amine, etc. may be used as the alkali component, and these may be used alone or in combination. The ethylene acrylic acid copolymer aqueous solution is dried on the surface of the material to form a polymer film, thereby preventing the penetration of moisture and improving the corrosion resistance of the material. In addition, it can also serve as a binder for fixing the organic wax dispersion applied to improve lubricity during processing of the material in a uniformly distributed state on the surface of the material. Suitable raw materials for the ethylene acrylic acid copolymer include Primaco 5980I (manufactured by SK Chemicals) and AC 5120 (manufactured by Honeywell), and the most suitable is Primaco 5980I.

As the water-soluble inorganic component, molybdate, tungstate, borate, silicate, and vanadate may be used, and preferably, molybdate or tungstate forming an oxide film may be used.

As the molybdate, as a specific example, sodium molybdate and potassium molybdate may be used. Specific examples of the tungstate include sodium tungstate and potassium tungstate. As the borate, sodium borate (sodium tetraborate, etc.), potassium borate (potassium tetraborate, etc.), or ammonium borate (ammonium tetraborate, etc.) may be used. As the silicate, sodium silicate, potassium silicate, or ammonium silicate may be used. Specific examples of the vanadate include sodium vanadate, sodium metavanadate, potassium vanadate, and potassium metavanadate.

In addition, nitrites, phosphates, amines, azoles, permanganates, peroxides, carbonates, zirconium compounds, calcium compounds, magnesium compounds, zinc compounds, and bismuth compounds may be used as the rust inhibitor. As a specific example of nitrite, sodium nitrite and potassium nitrite (K ₂ HPO ₃ ) may be used. Specific examples of the phosphate include sodium dihydrogenphosphate, disodium hydrogenphosphate, trisodium phosphate, sodium hypophosphite, sodium hypophosphite, potassium dihydrogenphosphate, dipotassium hydrogenphosphate, tripotassium phosphate, sodium pyrophosphate, potassium pyrophosphate, Sodium tripolyphosphate, potassium tripolyphosphate, potassium phosphite, potassium hypophosphite, calcium phosphite, zinc phosphite, aluminum phosphite, magnesium phosphite, aluminum orthophosphate, aluminum metaphosphate, or titanium hydrogen phosphate can be used. As specific examples of amines, diethanolamine and triethanolamine can be used. Specific examples of azoles include benzotriazole, methylbenzotriazole, 1-hydroxybenzotriazole, aminotriazole, and aminotetrazole. Examples of the permanganate include sodium permanganate and potassium permanganate. As the peroxide, hydrogen peroxide can be used as a specific example. Specific examples of the carbonate include sodium carbonate and potassium carbonate. Specific examples of the zirconium compound include water-dispersible zirconium oxide colloid, zirconium hydroxide, zirconium oxycarbonate, basic zirconium carbonate, zirconium potassium carbonate, ammonium zirconium carbonate, zirconium silicate, zirconium phosphate, zirconium titanate, zirconium tungstate, lithium zirconate, aluminum zirconate , magnesium zirconate can be used. As specific examples of the calcium compound, basic calcium molybdate, calcium silicate, and calcium tetraborate can be used. As a specific example of the magnesium compound, magnesium silicate can be used. As a specific example of the zinc compound, basic zinc molybdate can be used. Examples of the bismuth compound include bismuth orthovanadate. These may be used alone or in combination of two or more.

As the wax, a polyethylene-based wax, a fine wax dispersion, or a mixture thereof may be used. Preferably, a polyethylene-based resin and a fine wax dispersion may be mixed and used in a weight ratio of 2:1 to 3:1. The wax is water-soluble and can be micronized to 0.1 nm, improving uniformity of the film and increasing adhesion.

According to one embodiment of the present invention, the pH of the film-forming composition is preferably 8.5 to 9.5. If the pH is less than 8.5, reagglomeration of the wax may occur, and if the pH exceeds 9.5, the amount of the pH adjusting agent may be increased.

The film-forming composition contains 3 to 10% by weight of polyvinylpyrrolidone, 10 to 30% by weight of modified acrylic resin, 1 to 5% by weight of water-soluble inorganic component, 10 to 20% by weight of wax, and 1 to 5% by weight of rust inhibitor, based on the total weight of the film-forming composition. %, 0.1 to 1% by weight of a dispersion stabilizer and 40 to 60% by weight of pure water.

The film-forming composition may further include a pH adjusting agent, a chelating agent, and an antifoaming agent.

The film-forming composition is applied to a metal wire rod having a zinc calcium phosphate film at a temperature of 50 to 70 ° C for 3 to 5 minutes, and dried with hot air at a temperature of 60 to 100 ° C for 3 to 10 minutes or dried at room temperature for 3 to 5 hours. to form a polymer coating layer. After the drying step, the polymer particles are densely aligned and aligned, and when moisture is completely removed, the polymer particles form a dense coating layer.

A method for treating the surface of a metal wire rod according to the present invention includes the steps of pickling a rolled metal wire rod; forming a zinc calcium phosphate coating layer on the metal wire rod; coating a film-forming composition containing a polyvinylpyrrolidone resin, a modified acrylic resin, a water-soluble inorganic component and a wax, and an anti-rust component on the zinc calcium phosphate layer; and drying the coating to form a polymer coating layer.

In the drying step, hot air drying may be performed at a temperature of 60 to 100° C. for 3 to 10 minutes. According to another embodiment of the present invention, drying may be performed at room temperature for 3 to 5 hours.

The total weight of the film layer prepared by the method according to the present invention is 7 to 12 g / m 2, and the weight of only the polymer lubricating layer is generally 1 to 3 g / m 2 level.

The metal wire treated by the method according to the present invention has excellent corrosion resistance and excellent lubricity capable of 6-step forging in a multi-step former, so it is suitable for high-speed precision machining. In addition, the lubricating film is maintained even when the metal wire provided with the lubricating film according to the present invention is extruded and molded into a vehicle part having a very high strain rate (hexagonal to octagonal, yoke), so that precision parts can be manufactured. In addition, since the metal wire rod surface-treated by the method according to the present invention does not have an unreacted soap layer, no coating powder is generated.

The present invention will be described in detail with examples below, but the scope of the present invention is not limited by these examples.

Examples and Comparative Examples

A CHQ wire having a diameter of 28 mm was prepared, a zinc calcium phosphate layer was formed, and then washed and neutralized. A film-forming composition was prepared with the composition shown in Table 1 below, and a polymer film layer was formed. As the resin, a polyvinylpyrrolidone resin having a molecular weight of 20,000 to 40,000 and a modified acrylic resin (ethylene acrylic acid copolymer) were used. The wax was used by mixing polyethylene wax and fine wax dispersion in a weight ratio of 3:1. Sodium tungstate (Na ₂ WO ₄ 2H ₂ O) was used as the water-soluble inorganic component, and potassium phosphite (K ₂ HPO ₃ ) was used as the rust inhibitor.

Classification (unit: % by weight) Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Polyvinylpyrrolidone resin 5 10 - 25 Reactive metal soap (KPBL-100 treatment) Modified acrylic resin (solid content 25wt%) 20 15 25 - water-soluble inorganic ingredients 1.9 1.9 1.9 1.9 wax 16 16 16 16 rust inhibitor 2 2 2 2 dispersant 0.3 0.3 0.3 0.3 water balance balance balance balance Sum 100 100 100 100

Experimental Example 1: Measurement of wear resistance, corrosion resistance, friction coefficient and film removal

After forming the polymer coating layer, wear resistance, corrosion resistance, friction coefficient, and film removal were measured by the following methods. The results are shown in Table 2.

For wear resistance, a reciprocating distance of 10 mm was completed using a tribometer (pin on pin type), and the number of movements was measured until the friction coefficient reached 0.2 or more.

The friction coefficient was measured using a friction coefficient tester.

Corrosion resistance was conducted by adopting a test for promoting rusting under high temperature/high humidity conditions using a thermo-hygrostat (a so-called moisture resistance test). After using pure water and maintaining the test material in a thermo-hygrostat at a relative humidity of 95% and a temperature of 60 ° C for 72 hours, the red rust generation area was measured and evaluated (grade- 5: less than 5%, 4: less than 10%, 3: less than 50%, 2: less than 75%, 1: less than 90%).

In the film removal property evaluation, the film removal property of the lubricating film of the treated material after the drawing was completed was evaluated. The test piece was immersed in the following alkaline detergent, and the film remaining ratio was calculated by measuring the film weight before and after the film removal treatment (alkali detergent: 2% NaOH aqueous solution, film removal treatment conditions: liquid temperature 60 ° C., immersion time 3 minutes).

<Processing method>

Film weight measurement before film removal treatment → film removal treatment → water washing → drying → film weight measurement after film removal treatment.

[Equation 1]

<Evaluation Criteria (The lower the film remaining rate, the better the film removal property)>

○: film remaining rate is less than 3%, △: film remaining rate is less than 10%, Х: film remaining rate is 10% or more

division Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Abrasion resistance (times) 835 830 752 529 945 Corrosion resistance (1-5) 4 4 3 3 5 Coefficient of friction (0.1-0.5) 0.12 0.12 0.19 0.26 0.10 Demembrane (degreasing) ○ △ Х ○ ○

Experimental Example 2 : Film thickness measurement

The film weight of the wire rod prepared above and the film weight after drawing were measured and listed in Table 3 below. The material used in the test is SCM435, wire diameter 28.0mm (before drawing) / 25.66mm (after drawing), produced by the PASAIP process.

division Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 After fresh
1 layer coating (g/m ² ) 7.29 7.03 7.41 7.32 7.22 2-layer coating (g/m ² ) 3.08 1.99 2.02 2.46 4.62 Total coating amount (g/m ² ) 10.37 9.02 9.43 9.78 11.84 Diameter (mm) 25.66 25.66 25.66 25.66 25.66

Experimental Example 3: Moisture resistance evaluation

Moisture resistance was evaluated for the metal wire produced above. The moisture resistance test was conducted by adopting a test method for comparing corrosion resistance as a test for promoting rusting under high temperature/high humidity conditions using a thermo-hygrostat (aka moisture resistance test). After using pure water and maintaining the test material in a thermo-hygrostat for 72 hours under the conditions of 95% relative humidity and 60 ° C, the red rust generation area was measured and evaluated (grade- 5: less than 5%, 4: less than 10%, 3: less than 50%, 2: less than 75%, 1: less than 90%).

Moisture resistance evaluation of the wire rods prepared in Examples 1 and 2 was conducted for 72 hours on the materials before and after drawing, and the resulting photos are shown in FIGS. 2 and 3. The material used in the test is SCM435, after forming a phosphate film and a polymer film, and then producing a wire diameter of 28.0mm (before drawing) / 25.66mm (after drawing), PASAIP process.

Claims (9)

metal wire,
A zinc calcium phosphate film layer formed on the surface of the metal wire rod, and
Including a polymer film layer formed on the zinc calcium phosphate film layer,
The polymer film layer is formed using a film-forming composition containing a polyvinylpyrrolidone resin having a molecular weight of 20,000 to 40,000, a modified acrylic resin, a water-soluble inorganic component, and a wax,
The film-forming composition contains 3 to 10% by weight of polyvinylpyrrolidone resin, 10 to 30% by weight of modified acrylic resin, 1 to 5% by weight of water-soluble inorganic component, 10 to 20% by weight of wax, and 1 to 5% by weight of rust inhibitor, based on the total weight of the film forming composition. A metal wire rod comprising 0.1 to 1 wt% of a dispersion stabilizer and 40 to 60 wt% of pure water. The metal wire according to claim 1, wherein the water-soluble inorganic component is a tungstic acid salt. The metal wire according to claim 1, wherein the film-forming composition has a pH of 8.5 to 9.5. The metal wire according to claim 1, wherein a total weight of the calcium zinc phosphate coating layer and the polymer coating layer is 7 to 12 g/cm ² . pickling the rolled metal wire;
forming a zinc calcium phosphate coating layer on the metal wire rod;
coating a film-forming composition including a polyvinylpyrrolidone resin having a molecular weight of 20,000 to 40,000, a modified acrylic resin, a water-soluble inorganic component, and a wax on the zinc calcium phosphate film layer; and
Forming a polymer film layer by drying the coating with hot air at a temperature of 60 to 100 ° C. for 3 to 10 minutes or at room temperature for 3 to 5 hours;
The film-forming composition contains 3 to 10% by weight of polyvinylpyrrolidone resin, 10 to 30% by weight of modified acrylic resin, 1 to 5% by weight of water-soluble inorganic component, 10 to 20% by weight of wax, and 1 to 5% by weight of rust inhibitor, based on the total weight of the film forming composition. A method for treating the surface of a metal wire rod comprising 0.1 to 1 wt% of a dispersion stabilizer and 40 to 60 wt% of pure water. The method of claim 5, wherein the total weight of the zinc calcium phosphate coating layer and the polymer coating layer is 7 to 12 g/cm ² . delete delete delete

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