JPH11209781A - Lubricating oil for extractive draw processing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject lubricating oil capable of improving lubricity while leaving in-pipe residual oil at low levels after annealing operation to effect preventing a plug under extractive draw processing from scorching, therefore excellent in both characteristics, i.e., low residual oil level and high lubricity. SOLUTION: This lubricating oil is obtained by incorporating a base oil with 1-10 wt.% of a 6-10C fatty acid, wherein the base oil is such one as to contain Z70 wt.% of a polybutene with a 40 deg.C dynamic viscosity of 150-25,000 cSt and infrared absorbance I at 740 cm<-1> attributed to -(CH2 )n - of <0.00119 determined by infrared total reflection absorption method and have a 40 deg.C dynamic viscosity of 100-5,000 cSt by the addition of a glycol ether of the general formula: R-O-(R<1> O)m -(R<2> O)n -R3 (R and R<3> are each H or a hydrocarbon group; R<1> and R<2> are each an alkylene group; (n+n)=1-3).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drawing lubricating oil suitable for drawing a long annealed coil copper tube or the like used for a heat exchanger of an air conditioner or a refrigerator, and more particularly to a residual lubricating oil after annealing. The present invention relates to a lubricating oil for drawing that can reduce the amount of residue such as oil and other carbides and improve the lubricity and anti-seizure property of the inner surface of a pipe.

[0002]

2. Description of the Related Art A long annealed coil copper tube used for a heat exchanger of an air conditioner or a refrigerator, particularly a length of 1800 to 5 mm.
An ultra-long annealed coil copper tube of 000 m is usually processed into a copper tube by a drawing process using lubricating oil, and after winding this into a coil, the temperature is reduced to 500 ° C. or more in a reducing atmosphere or an inert atmosphere. Is subjected to heat annealing.

Conventionally, as the inner surface drawing oil of such a long annealed coil steel pipe, a lubricating oil having a kinematic viscosity adjusted by adding a fatty acid ester or lower isoparaffin to a high viscosity synthetic oil such as polybutene is mainly used. Oil has been used. Since the evaporating dry distillation temperature of these lubricating oils is usually 450 ° C. or less, during annealing after drawing, the lubricating oil is completely gasified by being vaporized or thermally decomposed in a copper pipe,
It is discharged out of the tube from the coil end.

[0004]

However, when the coil length is extremely long or the pipe diameter is extremely small, the gasified lubricating oil is not completely discharged out of the pipe.
In the cooling process, some of the gas components condense, producing residual oil and residues in the tubes.

Recently, chlorofluorocarbon has been regulated for environmental protection, and HFC (Hydrofluorocarbon) -based chlorofluorocarbon gas has been used as an alternative refrigerant in refrigeration systems such as air conditioners and refrigerators. However, since the HFC-based refrigerant and the hydrocarbon-based oil are not compatible with each other, when a copper tube coil is processed while residual oil is present in the tube to manufacture a heat exchanger such as an air conditioner or a refrigerator, the HFC-based refrigerant is not compatible with the hydrocarbon oil. The residual oil may hinder the operation of the refrigeration system or cause problems such as clogging of the capillary due to contamination.

[0006] The residual oil in the long annealed coil copper tube is as follows:
In brazing work at the time of assembling a heat exchanger such as an air conditioner and a refrigerator, it also causes a brazing failure. Further, when drawing is performed using a fatty acid ester as a viscosity modifier and then annealed, if residual oil is present in the tube, an anodized coil copper tube may give off-flavors.

In order to overcome these various disadvantages,
There is a strong demand for reducing residual oil in ultra-long coil copper tubes.

[0008] The present invention has been made in view of the above problems, and it is possible to reduce the residual oil in a pipe after annealing at a low level.
An object of the present invention is to provide a lubricating lubricating oil that can improve lubricity, thereby preventing seizure of a plug during drawing, and has both excellent properties of low residual oil and high lubricity. And

[0009]

The lubricating oil for drawing according to the first invention of the present application has a kinematic viscosity at 40 ° C. of 150 to 2500.
A 0CSt, when measuring the infrared absorbance I by infrared total reflection absorption method, - (CH _{2) n} - derived to 740c
containing 70% by weight or more of polybutene having an infrared absorbance I of less than 0.00119 at m- ¹ ;
¹ O) _m- (R ² O) _n -R ³ (where R and R ³ are hydrogen or hydrocarbon groups, R ¹ and R ² are alkylene groups having 2 or 3 carbon atoms, and m + n = 1 to 3) The kinematic viscosity at 40 ° C. is reduced to 100 by adding the glycol ether represented by the general formula
A lubricating oil of 5,000 cSt to 5000 cSt is used as a base oil.

The lubricating oil for drawing according to the second invention of the present application has a kinematic viscosity at 40 ° C. of 100 to 5000 cSt. When the infrared absorbance I is measured by the infrared total reflection absorption method,-(CH ₂ ) Polybutene having an infrared absorbance I at 740 cm ^-1 derived from _n-of less than 0.00119 is used as a base oil.

In the first invention and the second invention of the present application, 1 to 10% by weight of a fatty acid having 6 to 10 carbon atoms is added to these base oils.

The fatty acid preferably has 8 carbon atoms. Preferably, the fatty acid is octanoic acid or 2-ethylhexanoic acid.

In the present invention, n in polybutene is used.
-Absorbance I at 740 cm ^-1 for defining the butene ratio
Is a horizontal total reflection absorption measuring device, crystal length 70mm,
FT-IR manufactured by JEOL Ltd. using a crystal for liquid measurement made of ZnSe having a crystal thickness of 3 mm and equipped with an MCT detector.
Are measured under the conditions that the incident angle is 60 °, the resolution is 4 cm ⁻¹ , and the number of integrations is 1,000. Under these conditions, an infrared absorption spectrum corresponding to the number of reflections of 6.7 can be obtained.
It was determined as the absolute value of the absorption intensity per reflection of the — (CH ₂ ) _n — group appearing at ７４743 cm ⁻¹ .

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Some of the inventors of the present invention have reported that when the kinematic viscosity at 40 ° C. is 150 to 25000 cSt and the infrared absorbance I is measured by an infrared total reflection absorption method,
It contains 70% by weight or more of polybutene having an infrared absorbance I of less than 0.00119 at 740 cm ^-1 derived from-(CH ₂ ) _n-, and is RO- (R ¹ O) _m- (R ² O). _n- R
³ (where R and R ³ are hydrogen or a hydrocarbon group, R ¹ and R ² are an alkylene group having 2 or 3 carbon atoms, and m + n = 1 to 3). A drawing oil composed of a lubricating oil having a kinematic viscosity at 40 ° C. of 100 to 5000 cSt was filed by adding the same (Japanese Patent Application No. Hei.
9-112926, hereinafter referred to as a prior application). The drawing oil according to this prior application can reduce residual oil in a tube at low cost.

However, when drawing is performed using this lubricating oil, the residual oil in the pipe after annealing can be reduced. However, when the drawing frequency is high or the drawing rate is high, seizure occurs in the plug, and therefore the plug is seized. As the life is shortened and plug marks are generated in the pipe,
It has been found that the product value may be reduced.

Therefore, the inventors of the present application have further conducted various studies to develop a lubricating oil for drawing having both low residual oil properties and high lubricity. As a result, the present inventors have found that the residual oil property is reduced by using polybutene as a base oil as disclosed in the above-mentioned prior application, and the low residual oil property is reduced by adding an appropriate oleaginous agent thereto. It has been found that lubricity can be further improved without impairment.

The kinematic viscosity of the lubricating oil and the reasons for limiting the fatty acids to be added will be described below. Generally, in drawing a copper or copper alloy tube, lubricating oil is introduced between a steel or copper alloy tube and a plug to form an oil film. If the kinematic viscosity of the lubricating oil is less than 100 cSt, the lubricating property is poor because the amount of oil introduced during the drawing process is small and the oil film thickness is not sufficient. For this reason, seizure may occur between the copper tube and the plug, which may cause a reduction in the life of the plug and a breakage in drawing, which is unsuitable as a lubricating oil.

If the kinematic viscosity of the lubricating oil exceeds 5,000 cSt, an unnecessarily thick oil film is formed during the drawing process,
The amount of oil adhering to the inner surface of the copper tube after drawing increases, and as a result, the amount of oil remaining after annealing increases, which is not preferable because it causes brazing failure.

For the above reasons, the viscosity of the lubricating oil used for the copper pipe drawing is limited to 100 to 5000 cSt.

Even when polybutene has a kinematic viscosity of more than 5000 cSt, when the infrared absorbance I is measured by the infrared total reflection absorption method as in the invention according to claim 1 of the present application and the prior application,-(CH ₂ ) is obtained. _If the infrared absorbance I at 740 cm ⁻¹ derived from _n − is less than 0.00119, R
—O— (R ¹ O) _m — (R ² O) _n —R ³ (where R and R ³ are a hydrogen or hydrocarbon group, R ¹ and R ² are an alkylene group having 2 or 3 carbon atoms, m + n = 1 to 3) can be used in the present invention by adding the glycol ether represented by the general formula in a range of less than 30% by weight and adjusting the viscosity to 100 to 5000 cSt.

[0021] Fatty acids are known as oil agents and are said to reduce friction by adding them. As a general tendency, when the number of carbon atoms in the fatty acid increases, lubricity is improved by the addition of the fatty acid, but the boiling point increases, so that the residual oil property deteriorates. The present inventors have found that if the number of carbon atoms of the fatty acid to be added is smaller than 6, lubricity is not sufficient, and furthermore, corrosion sensitivity to copper is increased, and abnormalities such as discoloration may be caused. Further, in order to quickly dissipate from the tube during annealing, it is necessary that the boiling point be 270 ° C. or less. If the fatty acid has more than 10 carbon atoms, the boiling point exceeds 270 ° C., which may result in residual oil in the tube, which is not preferable. Therefore, additives are limited to fatty acids having 6 to 10 carbon atoms. Regarding toxicity, none of the compounds fall into the hazardous category, and there is no problem.

The fatty acid having 6 carbon atoms includes hexanoic acid. In addition, examples of the fatty acid having 8 carbon atoms include octanoic acid and 2-ethylhexanoic acid. Further, as the fatty acid having 9 carbon atoms, there is decanoic acid. On the other hand, pentanoic acid has 5 carbon atoms and lauric acid has 12 carbon atoms, and therefore cannot be used in the present invention.

In the present invention, the additive has 6 to 1 carbon atoms.
If the fatty acid is 0, the effect is exhibited without any practical problem.
On the other hand, the fatty acid to be added has an optimal carbon number due to the above-mentioned conflicting relationship between lubricity and residual oil properties. Among fatty acids having 6 to 10 carbon atoms, when the number of carbon atoms is 8 or more, lubricity becomes more excellent, so that a further extension of tool life can be expected. However, when the carbon number is 9 or 10, there is no problem in practical use, but the residual oil amount increases. Therefore, it is desirable to use a fatty acid having 8 carbon atoms as an additive. Further, among fatty acids having 8 carbon atoms, n-octanoic acid having a straight-chain structure is more preferable because of its large oily effect and excellent lubricity.

For the above reasons, the fatty acid, which is an additive which has both low residual oil properties and high lubricity, which meets the object of the present invention, has 6 to 10 carbon atoms, preferably carbon atoms. The number is 8, more preferably octanoic acid.

In the present invention, the amount of the fatty acid to be added is 1 to 10% by weight based on the whole lubricating oil composition. When the amount of the fatty acid added is less than 1% by weight, the lubricating property is insufficient, so that the tool life is not improved. On the other hand, if the amount of the fatty acid exceeds 10% by weight, the lubricating effect is saturated, and the effect corresponding to the amount cannot be expected, resulting in inefficiency. Further, when the amount of the fatty acid added exceeds 10% by weight,
All the lubricating oils cannot be volatilized at the time of annealing, and may become residual oils.

The fatty acid according to the present invention can be used for industrial use and reagent use without any problem.

[0027]

EXAMPLES The effects of the drawing lubricating oil according to the examples of the present invention will be described in comparison with the drawing lubricating oil of a comparative example which is out of the scope of the present invention. After the ingot of phosphorous deoxidized copper was hot extruded and cold rolled, it was subjected to a predetermined number of drawing operations with a bull block to obtain a tube having an outer diameter of 9.52 mm and a thickness of 0.41 mm. The lubricating oil was blended with the additives specified in the present invention to two kinds of base oils (A and B) and used for drawing. The base oil A is-(C
H ₂ ) Infrared absorbance I at 740 cm ⁻¹ derived from _n −
Is added to 5% of polybutene having a kinematic viscosity at 40 ° C. of less than 0.00119.
The base oil B was adjusted to 0 cSt, and the base oil B was-(CH
₂ ) The infrared absorbance I at 740 cm ^-1 derived from _n − is less than 0.00119 and the kinematic viscosity at 40 ° C. is 5000
It is a polybutene that is cSt.

After the drawing process, the copper tube is wound into a coil having a length of 2000 m, and at the time of annealing the tube, a nitrogen gas is flowed into the tube at a flow rate of 20 liter / min, and the tube is purged for 30 minutes. Annealing was performed in an annealing furnace.

From the coil after annealing, copper pipe samples for measuring residual oil of 15 points each having a length of 10 m were cut, and HCFC141 was cut.
b Residual oil in the tube was extracted by washing the inner surface with a solvent (hydrochlorofluorocarbon). After the extract was heated to evaporate the solvent component, the weight of residual oil in the tube was measured, and the amount of residual oil per 1 m of copper tube was calculated by subtracting the blank amount.

The burning of the tool was evaluated based on the total length of the copper tube that could be drawn before the burning mark was formed on the plug surface. The presence or absence of burning marks was visually or visually determined by an optical microscope. After the drawing total length reached 5 km, no plug seizure occurred. A case where no seizure occurred after 3 km was evaluated as ○. A case where seizure occurred after 3 km drawing was evaluated as x. In practice, a rating of ○ or more is judged to be good.

The brazing was evaluated by using BCuP-2 phosphor copper brazing (wire diameter: 1.6 mm), expanding the evaluation material, inserting a copper tube, and heating with propane gas for 6 seconds to braze. . Then, when the pipe was filled with a CFC gas having a pressure of 3.0 × 10 ⁴ Pa, no gas leakage due to no filling with the brazing material was indicated by “○”, and a gas leakage was indicated by “x”.

The results are shown in Tables 1 to 8 below. Tables 1 to 4 show types of additives, kinematic viscosity at 40 ° C., maximum residual oil content, and average residual oil content. Tables 5 to 8 show the presence / absence of seizure of the tool and the presence / absence of poor brazing. Tables 1 and 5 show examples of the base oil, and Tables 2 and 6 show the base oil B.
Tables 3 and 7 are comparative examples with base oil A, and Tables 4 and 8 are comparative examples with base oil B.

[0033]

[Table 1]

[0034]

[Table 2]

[0035]

[Table 3]

[0036]

[Table 4]

[0037]

[Table 5]

[0038]

[Table 6]

[0039]

[Table 7]

[0040]

[Table 8]

As shown in these Tables 1 to 8, the embodiment Nos. The drawing lubricating oils Nos. 1 to 24 had a small amount of residual oil in the pipe, did not cause seizure on the plug, and did not recognize gas leakage due to poor brazing.

On the other hand, in Comparative Example No. 1.3.9.11
Lubricating oils contain fatty acids (octanoic acid, 2-ethylhexanoic acid) having 8 carbon atoms, but the amount of addition is as small as 0.5%, so that good lubricating performance cannot be obtained. Then, the plug was seized.

Comparative Example No. In 2.4.10.12, a fatty acid having 8 carbon atoms (octanoic acid, 2-ethylhexanoic acid) is added, but since the amount of addition is as large as 15%, the residual oil in the tube after annealing is added. The amount was large and gas leakage due to poor brazing was observed.

Comparative Example No. In 5.6.13.14, since a fatty acid having five carbon atoms (pentanoic acid) was added, good lubrication performance was not obtained, and seizure occurred on the plug.

Comparative Example No. 7.8.15.16 is 12
Since a fatty acid having two carbon atoms (lauric acid) was added, the thermal decomposability during annealing was poor, and the amount of residual oil was large, so gas leakage due to poor brazing was observed.

Further, in Example No. 4 to 12 and Example N
o. Since 16 to 24 are fatty acids having 8 or more carbon atoms, lubricating properties are remarkably excellent. Therefore, the tool seizure evaluation is ◎. Example No. Since 10 to 12 and Examples 22 to 24 are fatty acids having 9 carbon atoms (decanoic acid), they have excellent lubricity and do not leak.

[0047]

As described in detail above, the lubricating oil for drawing according to the present invention has both low residual oil properties and high lubricity, and does not cause seizure of plugs and eliminates residual oil in the pipe. The copper or copper alloy tube with less amount can be manufactured with high efficiency.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C10N 40:24 (72) Inventor Akinori Tsuchiya 65, Hirasawa, Hadano-shi, Kanagawa Prefecture Kobe Steel Works, Hatano Plant

Claims (5)

[Claims] 1. A kinematic viscosity at 40 ° C. of 150 to 25,000.
cSt and the infrared absorbance I by the infrared total reflection absorption method.
740 cm derived from-(CH ₂ ) _n-
Polybutene infrared absorbance I is less than 0.00119 in ^-1 containing 70 wt% or ^{more, R-O- (R 1 O} ) m
— (R ² O) _n —R ³ (where R and R ³ are hydrogen or a hydrocarbon group, R ¹ and R ² are an alkylene group having 2 or 3 carbon atoms,
m + n = 1 to 3) by adding a glycol ether represented by the general formula of 40 ° C.
A lubricating oil for drawing, wherein a lubricating oil of 000 cSt is used as a base oil, and 1 to 10% by weight of a fatty acid having 6 to 10 carbon atoms is added thereto. 2. A kinematic viscosity at 40 ° C. of 100 to 5000 c.
St, and when the infrared absorbance I is measured by the infrared total reflection absorption method, 740 cm ^-1 derived from-(CH ₂ ) _n-
A polybutene having an infrared absorbance I of less than 0.00119 as a base oil to which a fatty acid having 6 to 10 carbon atoms is added in an amount of 1 to 10% by weight. 3. The drawing lubricating oil according to claim 1, wherein the fatty acid has 8 carbon atoms. 4. The lubricating oil for drawing according to claim 1, wherein the fatty acid is at least one selected from the group consisting of octanoic acid and 2-ethylhexanoic acid. 5. The lubricating oil for drawing according to claim 1, wherein the lubricating oil is an inner surface drawing oil for a long annealed coil copper tube.