JP2020139026A - Lubricant for drawing process - Google Patents

Abstract

To provide the lubricant for the drawing process for hard-to-process iron-based materials such as stainless steel (SUS), wherein the lubricant for the drawing process does not cause disconnection of wire during drawing, and does not cause discoloration such as seizure of the wire after drawing, even if the materials are fine wire or wire with a special shape.SOLUTION: The lubricant for the drawing process comprises a base oil and a branched olefin polymer, wherein a content of the branched olefin polymer is 0.01 to 5 wt.%, the branched olefin polymer is at least one selected from a group consisting of polyisobutylene, polyisoprene, ethylene/propylene copolymer, and styrene/butadiene copolymer, has an average molecular weight of 10,000 to 5 million, and kinematic viscosity at 40°C of the lubricant for the drawing process is 1 to 50 mm2/s.SELECTED DRAWING: None

Description

The present invention relates to a lubricant for drawing out iron-based materials such as stainless steel.

Compared to non-ferrous metal materials, iron-based materials such as stainless steel (SUS) have higher work hardening properties, and tools and materials tend to adhere to each other. Therefore, they are inferior in workability during wire drawing and have variations in product dimensions. There is a problem that it tends to grow. For this reason, in plastic working such as wire drawing and drawing of iron-based materials, components such as extreme pressure agents are added to the lubricant used to reduce the friction between the wire and the die.

As a lubricant for plastic processing of such an iron-based material, Patent Document 1 describes as a lubricant for cold drawing of a stainless steel tube, paraffin wax having a melting point of about 50 to 80 ° C., chlorinated paraffin, and phosphorus. A semi-solid or solid metal drawing lubricant at room temperature, which is a mixture of an acid ester or a paraffinic acid ester, is disclosed.

It is known that chlorine compounds are effective for plastic working of difficult-to-process materials such as stainless steel. However, from the viewpoint of consideration for the global environment, the development of non-chlorine-based lubricants for plastic working is underway. In Patent Document 2, as a lubricant composition for plastic working used for deep drawing of stainless steel, zinc dithiophosphate 40 to 70% by mass, a sulfur-based extreme pressure agent 20 to 50% by mass, and an organic acid salt 1 to 40 are used. A lubricant composition for plastic working containing% by mass is disclosed.
However, the lubricant containing an organic acid salt has a problem that a metal residue tends to remain on the wire after heat treatment at the time of drawing.

On the other hand, various lubricants are known for wire drawing of soft metals such as non-ferrous metals. For example, Patent Document 3 discloses a base oil made of a high molecular polymer having a viscosity of 600 cSt or more at 40 ° C., and a lubricating oil containing 2 to 25% by weight of the base oil or an aliphatic dicarboxylic acid. In Patent Document 3, by utilizing the excellent lubricity of fats and oils and aliphatic dicarboxylic acids and the characteristics of the base oil that the viscosity decrease with respect to temperature is small, the adhesive force of the lubricant to the wire rod surface is enhanced, and it is excellent in high-speed wire drawing. It is disclosed that it exhibits seizure resistance and lubrication performance and enables smooth wire drawing.

However, when drawing out a wire that is hard like stainless steel (SUS) and has a particularly small diameter, a highly viscous lubricant such as Patent Document 3 increases the amount of adhesion to the wire, so the wire is drawn during drawing. There is a problem that abrasion powder is caught between the die and the die, which leads to disconnection.

Japanese Unexamined Patent Publication No. 62-153396 Japanese Unexamined Patent Publication No. 2014-145052 Japanese Unexamined Patent Publication No. 1-282297

The present invention is a drawing lubricant for difficult-to-process iron-based materials such as stainless steel (SUS), and even if it is a thin wire or a wire having a special shape, it may be broken during drawing or may be used as a wire after drawing. It is an object of the present invention to provide a lubricant for drawing processing which does not generate seizure and residue.

The drawing lubricant of the present invention contains a base oil and a branched olefin polymer, and the content of the branched olefin polymer is 0.01 to 5% by weight, and the branched olefin polymer is polyisobutylene, polyisoprene, or the like. It is at least one selected from the group consisting of ethylene / propylene copolymers and styrene / butadiene copolymers, has an average molecular weight of 10,000 to 5 million, and has a kinematic viscosity at 40 ° C. of the drawing lubricant. Is 1 to 50 mm ² / s.
The content of the branched olefin polymer is preferably 0.1 to 3% by weight.
The branched olefin polymer is preferably polyisobutylene or polypropylene.
The kinematic viscosity of the drawing lubricant at 40 ° C. is preferably 1 to 30 mm ² / s.
The base oil is preferably at least one selected from the group consisting of esters, mineral oils, and solvents having a flash point of 50 to 150 ° C.

According to the present invention, the branched olefin polymer is added to the lubricant in a specific amount to adjust the kinematic viscosity in the range of 1 to 50 mm ² / s, thereby suppressing disconnection during drawing and wire rod after drawing. It is possible to provide a lubricant for drawing processing that does not leave seizure or the like. That is, since the drawing lubricant has a low viscosity, a small amount of a uniform film can be formed on the wire, so that there is no disconnection due to the lubricant intervening between the wire and the die, and seizure occurs after drawing. There is no discoloration due to. Therefore, it is suitably used for drawing out difficult-to-process wire rods such as stainless steel (SUS) and fine wire materials. Further, the drawing lubricant does not generate a residue on the wire after the drawing process.

FIG. 1 is a schematic view of a Bowden testing machine. FIG. 2 is a diagram showing a state in which a SUS wire is pulled out through a carbide die and processed into a small diameter.

The drawing lubricant of the present invention contains a base oil and a branched olefin polymer, and the content of the branched olefin polymer is 0.01 to 5% by weight, and the branched olefin polymer is polyisobutylene, polyisoprene, or the like. It is at least one selected from the group consisting of ethylene / propylene copolymers and styrene / butadiene copolymers, has an average molecular weight of 10,000 to 5 million, and has a kinematic viscosity at 40 ° C. of the drawing lubricant. Is 1 to 50 mm ² / s.

Hereinafter, each requirement of the drawing lubricant will be described in detail.
The drawing lubricant contains a base oil and a branched olefin polymer.
The base oil is preferably at least one selected from the group consisting of mineral oils, esters, and solvents having a flash point of 50 to 150 ° C.
Mineral oil is an oil derived from petroleum, and most of its components are aromatic hydrocarbons, paraffinic hydrocarbons and naphthenic hydrocarbons. The kinematic viscosity range is as wide as ² to 1000 mm ² / s, and there are mineral oils having various viscosities. However, in the present invention, it is more preferable to use mineral oils having a kinematic viscosity of ² to 100 mm ² / s. In the present invention, viscosity refers to kinematic viscosity. The kinematic viscosity is a value (mm ² / s) obtained by dividing the viscosity of the sample by the density under the same conditions (temperature, pressure).

The ester is a fatty acid ester oil represented by the general formula R ¹ C (= O) OR ² (R ¹ is an alkyl group having 8 to 20 carbon atoms; R ² is an alkyl group having 1 to 24 carbon atoms), and a polyol ester. Is preferable. Specific examples of fatty acid ester oils include methyl caprylate, ethyl caprylate, propyl caprylate, butyl caprylate, 2-ethylhexyl caprylate, methyl pelargonate, ethyl pelargonate, propyl pelargonate, butyl pelargone, methyl caprate. , Ethyl caprate, propyl caprate, butyl caprate, methyl laurate, ethyl laurate, propyl laurate, butyl laurate, methyl myristate, ethyl myristate, propyl myristate, butyl myristate, methyl palmitate, palmitin There are ethyl acid, propyl palmitate, butyl palmitate, methyl stearate, ethyl stearate, propyl stearate, butyl stearate, methyl oleate, ethyl oleate, propyl oleate, butyl oleate and the like. Specific examples of the polyol ester include pentaerythritol tetraoleate, trimethylolpropane tricaplate, trimethylolpropane palm precipitated fatty acid ester, trimethylolpropane trioleate, trimethylolpropane tetraheptanoate, and various complex esters.

Examples of the solvent having a flash point of 50 to 150 ° C. include a hydrocarbon solvent. Specifically, normal paraffinic hydrocarbons such as nonane, decane, undecane and dodecane; 2,2,4-trimethylpentane, 2,2,4,6,6-pentamethylheptan, 2-methylpentane and 2, Isoparaffin-based hydrocarbons such as 2-dimethylbutane; saturated hydrocarbon solvents such as naphthenic hydrocarbons such as cyclohexane, cyclooctane, cyclodecane and decahydronaphthalene; and aromatic hydrocarbon solvents such as benzene, toluene, xylene and alkylbenzene; Examples thereof include unsaturated hydrocarbon solvents such as olefin hydrocarbons.

That is, the base oil usually used for the lubricant can be added to the drawing processing lubricant of the present invention. Of these, mineral oil and ester are preferable, and ester oil is more preferable from the viewpoint of lubricity and adsorptivity of the iron-based wire rod to the new surface. This is because the ester oil has a polar group in the molecule that strongly bonds with the metal, and forms an adsorption film with good lubricity on the metal surface. Further, in the case of a compound having a long carbon chain even in an ester oil, the carbon chain portion forms an adsorption film on the metal surface by physical adsorption or chemical adsorption. Therefore, the ester forms an adsorption film on the surface of a metal such as a drawing material or a die, and exhibits an effect of reducing wear even under conditions of a relatively low temperature and a low load.
The above base oil may be used alone or in combination of two or more.

The content of the base oil is usually 95 to 99.99% by weight, preferably 97 to 99.9% by weight, and more preferably 98 to 99.9% by weight in the total of the base oil and the branched olefin polymer. By appropriately changing the content of the base oil within the above range, the kinematic viscosity of the drawing lubricant can be easily adjusted.

The branched olefin polymer is at least one selected from the group consisting of polyisobutylene, polyisoprene, ethylene / propylene copolymer and styrene / butadiene copolymer, and has an average molecular weight of 10,000 to 5 million.
In addition, polyisobutylene, polyisoprene, ethylene / propylene copolymer, and styrene / butadiene copolymer may be hydrogenated, and the hydrogenation may be complete hydrogenation saturation or partial hydrogenation.
As these branched olefin polymers, polyisobutylene or polyisoprene is preferable. The average molecular weight thereof is preferably 30,000 to 4 million, more preferably 50,000 to 3 million. The average molecular weight refers to the number average molecular weight (Mn) measured by gel permeation chromatography (GPC). The kinematic viscosity of the drawing lubricant can be adjusted by appropriately changing the average molecular weight of the branched olefin polymer within the range of 10,000 to 5 million. The larger the molecular weight, the higher the viscosity, and the smaller the molecular weight, the lower the viscosity. If the average molecular weight of the branched olefin polymer exceeds 5 million, the compatibility with the base oil is lowered, and a uniform state may not be maintained. On the other hand, if the average molecular weight of the branched olefin polymer is less than 10,000, the lubricity of the drawing lubricant may be insufficient.

The content of the branched olefin polymer is 0.01 to 5% by weight, preferably 0.1 to 3% by weight, and more preferably 0.1 to 2% by weight in the total of the base oil and the branched olefin polymer. If the content of the branched olefin polymer is less than 0.01% by weight, the lubricity of the drawing lubricant may not be sufficient. On the other hand, if it exceeds 5% by weight, the risk of disconnection due to the abrasion powder getting caught in the surface of the wire due to the high viscosity increases.

In the present invention, by adding a branched olefin polymer having a bent structure to the lubricant for drawing processing, the oil film breaks even when the branched olefin polymer is in an excessive friction state with high shear stress due to its leopexiness. Is less likely to occur, and seizure can be prevented.

In addition to the base oil and the branched olefin polymer, the above-mentioned lubricant for drawing processing includes sulfur-based extreme pressure additives such as polysulfide and sulfide oil and fat, inorganic substances such as calcium carbonate, and phosphorus within a range that does not impair the effects of the present invention. Additives such as phosphorus-based extreme pressure additives such as acid esters and phosphite esters, zinc dithiophosphate, and heat-resistant resins such as PTFE (polytetrafluoroethylene) may be added. The content of these additives is usually 0.1 to 30% by weight, preferably 0.1 to 15% by weight, and more preferably 0.1 to 5% by weight in the entire composition.

The drawing lubricant can be prepared by stirring and mixing a base oil, a branched olefin polymer and other optional components by a usual method.

Kinematic viscosity at 40 ° C. of the drawing lubricant is usually 1 to 50 mm ² / s, preferably 1 to 30 mm ² / s. If the kinematic viscosity exceeds 50 mm ² / s, the amount of adhesion may increase, and there is a concern that abrasion powder or the like may be caught during the drawing process, leading to disconnection.

Here, the lubricity of the drawing lubricant is evaluated by a slip distance test as shown in FIG. That is, a small amount of the drawing lubricant 1 is dropped onto the test steel plate 2 placed on the support base 3, the steel ball 5 is pressed with a constant load W, and the drawing lubricant 1 is slid at a constant sliding speed. , The frictional force P acting on the steel ball 5 is detected by a strain gauge, and the friction coefficient μ is calculated by the formula μ = P / W. In the present invention, the average coefficient of friction when sliding a distance of 25 mm 20 times is defined as lubricity.

The lubricant for drawing processing of the present invention is particularly preferably used for drawing processing of difficult-to-process iron-based metals such as stainless steel (SUS). FIG. 2 shows a state in which the SUS wire rod 7, which is a typical example of such a difficult-to-process material, is pulled out through the cemented carbide die 6 and processed into a thin wire. The drawing lubricant is particularly suitable for thinning, and a fine wire having a wire diameter of 0.1 to 1 mm can be obtained. The drawing lubricant of the present invention can be widely used as a lubricant for other applications such as pressing, drawing, ironing, bending, rolling and cold forging. Needless to say.

Hereinafter, the present invention will be described in more detail based on Examples and Comparative Examples, but the present invention is not limited to these Examples and the like.
[Example 1]
[1] Preparation of lubricant for drawing processing 2-ethylhexyl caprylate (kinematic viscosity 2.5 mm ^{2 / s)} 99.9% by weight as a base oil and polyisoprene (average molecular weight 50,000) 0.1 as a branched olefin polymer Samples were prepared by mixing with% by weight.
The content of each component is shown in Table 2. In Examples and Comparative Examples, the total of the base oil and the branched olefin polymer is 100% by weight.

[2] Evaluation of lubricant for drawing process (1) Dynamic viscosity Measured according to JIS K 2283. Specifically, a predetermined amount of sample was placed in a Canon Fenceke viscometer and allowed to stand until it reached a predetermined temperature. Then, the time for the sample to pass through the predetermined range was measured, and the kinematic viscosity was calculated using the coefficient. The results are shown in Table 2.

結果を表２に示す。摩擦係数が低いほど、潤滑剤として優れた性能を有する。摩擦係数が０．１５未満であれば良好、０．１５〜０．２０は概ね良好、０．２０を超える場合は問題ありと判断した。 (2) Lubricity (coefficient of friction)
The lubricity of each sample was evaluated by the Bowden test. Specifically, the sample was applied onto the test steel plate, the steel ball was pressed with a constant load (load load W), and the steel ball was reciprocated at a sliding speed V. At that time, the frictional force P acting on the steel ball was detected by a strain gauge, and the friction coefficient μ was calculated by the formula μ = P / W. The outline of the testing machine is shown in FIG. 1, and the test conditions are shown in Table 1.

The results are shown in Table 2. The lower the coefficient of friction, the better the performance as a lubricant. If the friction coefficient is less than 0.15, it is good, 0.15 to 0.20 is generally good, and if it exceeds 0.20, it is judged that there is a problem.

(3) Residue test The presence or absence of residue in each sample was confirmed by thermogravimetric analysis (TGA).
An aluminum pan on which 15 ± 3 mg of the sample was placed was placed in a chamber and heated to 800 ° C. at a heating rate of 20 ° C./min under an air flow at a flow rate of 300 ml / min, and then the amount of residue was visually observed. In Table 2, no residue was indicated as "none", and with residue was indicated as "present".

(4) Adhesion amount test After the steel plate (60 mm × 80 mm) was completely immersed in the sample, it was pulled up, suspended vertically, and allowed to stand for 24 hours. The adhesiveness of the sample was evaluated from the change in weight before and after standing. In Table 2, it was judged that the adhesion amount was less than 20 mg, which was good, and 20 mg or more was problematic.

[Example 2]
A sample was prepared in the same manner as in Example 1 except that polyisoprene (average molecular weight of 3 million) was used instead of polyisoprene (average molecular weight of 50,000) as the branched olefin polymer.
The obtained lubricant for drawing processing was evaluated in the same manner as in Example 1.

[Example 3]
Samples were prepared in the same manner as in Example 1 except that polyisoprene (average molecular weight 500,000) was used instead of polyisoprene (average molecular weight 50,000) as the branched olefin polymer.
The obtained lubricant for drawing processing was evaluated in the same manner as in Example 1.

[Example 4]
In Example 1, the same as in Example 1 except that mineral oil (kinematic viscosity 10 mm ² / s) was used instead of ² -ethylhexyl caprylic acid (kinematic viscosity 2.5 mm ² / s) as the base oil. Samples were prepared.
The obtained lubricant for drawing processing was evaluated in the same manner as in Example 1.

[Example 5]
Example 1 except that an isoparaffin-based solvent (kinematic viscosity 2.5 mm ² / s) was used instead of caprylic acid 2-ethylhexyl (kinematic viscosity 2.5 mm ² / s) as the base oil in Example 1. A sample was prepared in the same manner as above.
The obtained lubricant for drawing processing was evaluated in the same manner as in Example 1.

[Example 6]
In Example 1, the amount of ² -ethylhexyl caprylate (kinematic viscosity 2.5 mm ² / s) was changed from 99.9% by weight to 99.5% by weight, and polyisoprene (average molecular weight 50,000). Samples were prepared in the same manner as in Example 1 except that the amount was changed from 0.1% by weight to 0.5% by weight.
The obtained lubricant for drawing processing was evaluated in the same manner as in Example 1.

[Example 7]
In Example 1, the amount of ² -ethylhexyl caprylate (kinematic viscosity 2.5 mm ² / s) was changed from 99.9% by weight to 99.0% by weight, and polyisoprene (average molecular weight 50,000). Samples were prepared in the same manner as in Example 1 except that the amount was changed from 0.1% by weight to 1.0% by weight.
The obtained lubricant for drawing processing was evaluated in the same manner as in Example 1.

[Example 8]
In Example 1, the amount of ² -ethylhexyl caprylate (kinematic viscosity 2.5 mm ² / s) was changed from 99.9% by weight to 98.0% by weight, and polyisoprene (average molecular weight 50,000). Samples were prepared in the same manner as in Example 1 except that the amount was changed from 0.1% by weight to 2.0% by weight.
The obtained lubricant for drawing processing was evaluated in the same manner as in Example 1.

[Example 9]
In Example 1, the amount of ² -ethylhexyl caprylate (kinematic viscosity 2.5 mm ² / s) was changed from 99.9% by weight to 97.0% by weight, and polyisoprene (average molecular weight 50,000). Samples were prepared in the same manner as in Example 1 except that the amount was changed from 0.1% by weight to 3.0% by weight.
The obtained lubricant for drawing processing was evaluated in the same manner as in Example 1.

[Example 10]
In Example 1, the amount of ² -ethylhexyl caprylate (kinematic viscosity 2.5 mm ² / s) was changed from 99.9% by weight to 99.99% by weight, and polyisoprene (average molecular weight 50,000). Samples were prepared in the same manner as in Example 1 except that the amount was changed from 0.1% by weight to 0.01% by weight.
The obtained lubricant for drawing processing was evaluated in the same manner as in Example 1.

The content of the branched olefin polymer was 1.0% by weight (Example 7), 2.0% by weight (Example 8),
And 3.0% by weight (Example 9), the kinematic viscosity increased and the amount of adhesion increased. It can be seen that a desired drawing lubricant can be obtained by appropriately adjusting the amount of the branched olefin polymer added. In the sample of Example 10, since the content of the branched olefin polymer was small, the friction coefficient was higher than that of the other Examples.

[Comparative Example 1]
Using 2-ethylhexyl caprylate (kinematic viscosity 2.5 mm ² / s) as a base oil as a sample, the sample was evaluated in the same manner as in Example 1.
The sample of Comparative Example 1 showed a high coefficient of friction. It is probable that the lubricity was low because the branched olefin polymer was not added.

[Comparative Example 2]
In Example 1, the amount of ² -ethylhexyl caprylate (kinematic viscosity 2.5 mm ² / s) was changed from 99.9% by weight to 40% by weight, and in addition to 2-ethylhexyl caprylate as a base oil, Except for the use of 54% by weight of pentaerythritol tetraoleate (kinematic viscosity 64 mm ² / s) and the change in the amount of polyisoprene (average molecular weight 50,000) from 0.1% by weight to 6.0% by weight. Prepared a sample in the same manner as in Example 1.
The sample was evaluated in the same manner as in Example 1.
In the sample of Comparative Example 2, since the content of the branched olefin polymer was high, an increase in kinematic viscosity and an increase in the amount of adhesion were confirmed.

[Comparative Example 3]
A sample was prepared by mixing 95% by weight of ² -ethylhexyl caprylate (kinematic viscosity 2.5 mm ² / s) and 5.0% by weight of calcium sulfonate as a base oil.
The sample was evaluated in the same manner as in Example 1.
In the sample of Comparative Example 3, since calcium sulfonate was added, as a result of TGA, a residue that appeared to be a metal was observed.

1 Lubricant for drawing processing 2 Test steel plate 3 Support base 4 Cylindrical rod 5 Steel ball 6 Carbide die 7 SUS wire rod

Claims (5)

A drawing lubricant containing a base oil and a branched olefin polymer.
The content of the branched olefin polymer is 0.01 to 5% by weight.
The branched olefin polymer is at least one selected from the group consisting of polyisobutylene, polyisoprene, ethylene / propylene copolymer, and styrene / butadiene copolymer, and has an average molecular weight of 10,000 to 5 million.
A lubricant for drawing processing, wherein the kinematic viscosity of the lubricant for drawing processing at 40 ° C. is 1 to 50 mm ² / s. The lubricant for drawing processing according to claim 1, wherein the content of the branched olefin polymer is 0.1 to 3% by weight. The lubricant for drawing processing according to claim 1 or 2, wherein the branched olefin polymer is polyisobutylene or polypropylene. The lubricant for drawing processing according to any one of claims 1 to 3, wherein the kinematic viscosity of the lubricant for drawing processing at 40 ° C. is 1 to 30 mm ² / s. The lubricant for drawing processing according to any one of claims 1 to 4, wherein the base oil is at least one selected from the group consisting of an ester, a mineral oil, and a solvent having a flash point of 50 to 150 ° C.

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