JP2000282078A - Oil for cold rolling and cold rolling using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an oil for cold rolling capable of cold rolling various kind of steel sheets in high efficiency and holding high surface quality by including an oil in water type emulsion obtained by diluting a stock solution including a base oil such as a synthetic ester or the like and a specific cationic surfactant or the like, with water. SOLUTION: This oil comprises the oil in water type emulsion obtained by diluting the stock solution with water. The stock solution is comprising the base oil including only a synthetic ester or a mixture of the synthetic ester and mineral oil or/and fats and oils, cationic surfactant obtained by mixing 1-5 wt.% of N-monoalkyl or N-monoalkenyl diamine expressed by the formula (R1 is a 12-18C alkyl or alkenyl; R2 is a 2-4C alkylene) and a 6-10C organic acid in the molar ratio of N-monoalkyl or N-monoalkenyl diamine/organic acid = 1/7-1/15 and 1-5% of a nonionic surfactant, and manifesting pH 6.5-4.5. Steel sheets are preferably obtained by cold rolling using this oil for cold rolling.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cold rolling oil used for cold rolling of a steel sheet and a rolling method using the same, and in particular, to a steel sheet of various materials, for example, a low carbon steel sheet, a high carbon steel sheet, The present invention relates to a cold rolling oil capable of rolling a silicon steel plate, a stainless steel plate, or the like with one type of oil with good surface properties and high efficiency, and a rolling method using the same.

[0002]

2. Description of the Related Art Generally, in the cold rolling of steel sheets, a wide range of materials are used, from low deformation steels such as low carbon steel to high deformation steels such as high carbon steel, silicon steel and stainless steel. Rolling is performed, and the product thickness after rolling is also from a thick material of about 1.5 to 3.2 mm,
There is a wide variety of materials, from about 0.15 mm to about 0.25 mm.

[0003] Therefore, rolling oil and a rolling mill are properly used depending on the type of steel and the thickness of a product to perform rolling. For example, as a rolling oil for low carbon steel, a mineral oil is used as a base oil, and an emulsifier is added to the base oil and emulsified in water to form an emulsion (hereinafter also referred to as an oil-in-water type emulsion). Is an oil-in-water emulsion using a base oil of fats and oils or synthetic esters. For rolling oils such as ferritic stainless steel that requires surface gloss, neat oil containing mineral oil as the main component (used straight without emulsification) ) Is used.

[0004] A tandem rolling mill with high productivity is used for rolling low deformation steel such as low carbon steel, while Sendzimere rolling is used for rolling high deformation steel such as high carbon steel and stainless steel. A small diameter multi-stage rolling mill such as a mill is used.

Recently, there has been an increasing demand for rolling stainless steel with a large diameter tandem type rolling mill from the viewpoint of productivity. As a rolling oil, rolling of various materials such as carbon steel and stainless steel with one kind of oil is performed. There is a need for a rolling oil that can be used. However, when a ferritic stainless steel is rolled using a tandem rolling mill, for example, a rolling oil made into an emulsion using a mineral oil used as a base oil for rolling low carbon steel, the glossiness of the steel sheet surface after rolling becomes Sendzimir. There is a problem that it is significantly reduced as compared with rolling. Further, when carbon steel is rolled with neat oil used for rolling stainless steel, seizure occurs, so that there is a problem that the rolling speed is limited and the production efficiency is reduced.

As a countermeasure against such a problem, Japanese Patent Laid-Open No.
Japanese Patent No. 110195 discloses a cold rolling oil having a low viscosity by using a fatty acid low molecular weight alcohol ester as a base oil and adding a polymer fatty acid ester to the base oil.

[0007]

However, even with the rolling oil disclosed in JP-A-2-110195, the glossiness obtained by rolling stainless steel with a tandem-type rolling mill is low, and it is difficult to obtain the glossiness required in the market. No proper surface properties can be obtained.

[0008] An object of the present invention is to provide a rolling oil which can roll steel sheets of various materials with high efficiency with one kind of rolling oil, and which can improve the surface quality of a product obtained by rolling, and a use of the rolling oil. To provide a rolling method.

[0009]

Means for Solving the Problems In order to solve the above-mentioned problems, the inventors of the present invention have proposed an emulsifier required for diluting a base oil in water to form an emulsion, the type of the emulsifier, the emulsion properties and the abrasion powder. We examined the relationship and obtained the following findings.

(1) A synthetic oil alone or a mixture of a synthetic ester and a fat or oil or a mineral oil or a mixture of a monoester and a mineral oil is used as a base oil, to which a cationic emulsifier is added to obtain an oil-in-water emulsion. Since the surface of the oil particles is charged with the rolling oil, even if the oil particles float and separate from the water by, for example, allowing the rolling oil to stand still in a tank, it is emulsified again with simple stirring and a uniform emulsion. Becomes

(2) In particular, when a mixture of a specific N-monoalkyl or N-monoalkenyldiamine and a specific organic acid is used as the cationic emulsifier, the separation speed upon standing is high, and Also, re-emulsification is easy.

(3) The rolling oil is weakly acidic (pH: 4.5 to 4.5)
In the case of 6.5), the surface potential of the oil particles in the rolling oil to which the cationic emulsifier is added and the potential of the abrasion powder mixed in the rolling oil are positive (positive), and the oil particles and the abrasion powder are electrically repelled. As a result, the adhesion of wear powder to oil particles is suppressed, and an emulsion with less wear powder is obtained.

(4) The cationic emulsifier deteriorates the initial emulsifiability of the emulsion, but the problem of the initial emulsifiability can be solved by using a nonionic emulsifier in combination with the cationic emulsifier.

(5) By separating the rolling oil into emulsions having different concentrations by, for example, allowing the rolling oil to stand in a tank, an emulsion having a high concentration and a large oil particle size and an emulsion having a low concentration and a small oil particle size are obtained. Can be The former emulsion is suitable for rolling thin steel sheets and hard-to-process steel sheets (high carbon steel, silicon steel, austenitic stainless steel, etc.) that require high lubricity. The latter emulsion is suitable for glossy steel sheets (ferritic stainless steel). Suitable for rolling steel. Further, by mixing the respective emulsions obtained by separation, it is possible to prepare an appropriate emulsion according to the material and the plate thickness.

The present invention has been completed based on the above findings, and the gist thereof is as follows.

(1) Using a synthetic ester alone or a mixture of a synthetic ester and a mineral oil or an oil or fat as a base oil, 1 to 5% by weight of N-monoalkyl or N-monoalkenyldiamine represented by the formula (1) and carbon A cationic emulsifier obtained by mixing an organic acid having a number of 6 to 10 with the N-monoalkyl or N-monoalkenyldiamine at a molar ratio of 1/7 to 1/15, and a nonionic emulsifier of 1 to 5 wt%. Consisting of an oil-in-water emulsion obtained by diluting an undiluted solution containing water with water, and having a pH of 6.5 to 4.
5. Cold-rolling oil characterized by being 5.

[0017]

Embedded image

(2) A mixture of a monoester and a mineral oil is used as a base oil, and an N-monoalkyl or N-
Monoalkenyl diamine of 1 to 5 wt% and carbon number of 6 to
A stock solution containing a cationic emulsifier obtained by mixing the organic acid of No. 10 with the above N-monoalkyl or N-monoalkenyldiamine at a molar ratio of 1/7 to 1/15, and 1 to 5% by weight of a nonionic emulsifier Consisting of an oil-in-water emulsion obtained by diluting water with water and having a pH of 6.
Cold-rolling oil characterized by being 5 to 4.5.

[0019]

Embedded image

(3) The cold rolling oil described in the above item (1) or (2) is separated into a plurality of emulsion rolling oils having different concentrations, and one of the separated rolling oils or the separated rolling oil is subjected to a predetermined process. A method for rolling a steel sheet, comprising supplying rolling oil mixed in a ratio to a rolled steel sheet to perform rolling.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Emulsifiers which are generally diluted with water and added to a base oil of a rolling oil used as an oil-in-water emulsion include cationic, anionic and nonionic emulsifiers.

A cationic emulsifier is a compound in which a portion having a hydrophilic group becomes a cation (cation) when dissolved in water. For example, a primary amine such as monomethylamine, laurylamine, and stearylamine is reacted with an acid. Salts include salts of secondary amines and acids such as dimethylamine, dilaurylamine and distearylamine, and salts of tertiary amines and acids such as trimethylamine, lauryldimethylamine and stearyldimethylamine.

The nonionic emulsifier does not become an ion when dissolved in water, and examples thereof include polyoxyethylene alkyl ether and polyoxyethylene phenol ether.

An anionic emulsifier is an emulsifier in which a portion having a hydrophilic group becomes an anion (negative ion) when dissolved in water.

FIG. 1 is a graph schematically showing the relationship between the pH of an emulsion when an emulsifier is added to a base oil and the potential of oil particles and abrasion powder in the emulsion.

As shown in FIG. 1, when an anionic or cationic emulsifier is added to a base oil to form an emulsion, charged oil particles are formed. In the case of the anionic type, the charge is negative, and in the case of the cationic type, the oil particles are repelled by any of the emulsifiers. Therefore, it is stable as oil particles.

However, due to the difference in specific gravity between oil and water, when the emulsion is allowed to stand, the oil particles gradually float and separate into an emulsion having a high oil concentration and an emulsion having a low oil concentration. At this time, if the electric repulsion between the oil particles is small, the aggregation and coalescence of the oil particles remarkably become an oil layer and float. Further, it is difficult to re-emulsify the oil layer that has floated up when it is reused.

If the repulsive force is too large, the oil particles may coagulate.
It is difficult for coalescence to occur, the floating of the oil particles is slow, and an emulsion having an appropriate concentration cannot be obtained.

Here, the first rolling oil of the present invention is based on a synthetic ester alone or a mixture of a synthetic ester and a mineral oil or an oil or fat, and comprises an N-monoalkyl or N-alkyl compound represented by the formula (1). Monoalkenyl diamine from 1 to 5
wt% and an organic acid having 6 to 10 carbon atoms is 1/7 of the N-monoalkyl or N-monoalkenyldiamine.
A cationic emulsifier mixed at a molar ratio of １／1/15,
It is characterized by comprising an oil-in-water emulsion obtained by diluting a stock solution containing 1 to 5% by weight of a nonionic emulsifier with water, and having a pH of 6.5 to 4.5.

The second rolling oil of the present invention comprises a mixture of a monoester and a mineral oil as a base oil, and contains 1 to 5% by weight of N-monoalkyl or N-monoalkenyldiamine represented by the formula (1). A cationic emulsifier obtained by mixing an organic acid having 6 to 10 carbon atoms in a molar ratio of 1/7 to 1/15 with respect to the N-monoalkyl or N-monoalkenyldiamine, and a 1 to 5 wt% nonionic emulsifier And an oil-in-water emulsion obtained by diluting a stock solution containing the above with water, and the pH of the emulsion is 6.5 to 4.5. Hereinafter, N-monoalkyl or N-monoalkenyldiamine is referred to as "alkylalkylenediamine".

By using a synthetic ester as the base oil, the lubricity of the rolling oil is improved and the coefficient of friction is reduced. Further, by adding a mineral oil or fat or oil, the wettability and seizure resistance are improved. Synthetic esters are esters of alcohol and carboxylic acid, such as isopropyl palmitate, octyl stearate, propylene glycol caprylate diester, trimethylolpropane isostearate triester, trimethylolethaneethane caprylate diester, dibutyl dimerate, and dioctyl adipate. And monoesters, diesters, triesters and the like.

By using a mixture of a monoester and a mineral oil as a base oil, the gloss of a steel sheet surface obtained by rolling is particularly improved. The monoester refers to an ester of a fatty acid that is a monovalent carboxylic acid and an aliphatic alcohol that is a monovalent alcohol, and examples thereof include isopropyl myristate, isopropyl palmitate, and butyl stearate.

By including a cationic emulsifier as an emulsifier, the oil particles become large and easily floated and separated, and the properties of the emulsion can be stably maintained in a weakly acidic state, and the abrasion powder adheres to the oil particles. Can be effectively suppressed. In addition, when an anionic emulsifier is used, the oil particles are small and it is difficult to float and separate, and the emulsion properties are unstable such as changing from alkaline to neutral with time, and the abrasion powder adheres to the oil particles. easy.

As a cationic emulsifier, a mixture of an alkylalkylenediamine of the formula (1) and an organic acid (ie,
By using (salt), the floating separation speed of oil particles is extremely high, and re-emulsification is also easy. However, equation (1)
When the number of carbon atoms in the alkyl group exceeds 18 and the number of carbon atoms in the alkylene group between two N atoms exceeds 4, it becomes difficult to dissolve the alkyl alkylenediamine in the base oil. When the alkyl group has less than 12 carbon atoms, the alkylalkylenediamine is eluted from the oil particles into water and the oil particles are difficult to float and separate. Therefore, the alkyl group of the alkylalkylenediamine has 12 to 18 carbon atoms, and the alkylene group has 2 to 4 carbon atoms.

Alkylalkylenediamines having 12 to 18 carbon atoms in the alkyl group and 4 or less carbon atoms in the alkylene group include N-laurylethylenediamine, N-laurylpropylenediamine, N-laurylbutylenediamine,
Lauryl isobutylene diamine, N-myristyl ethylenediamine, N-myristyl propylene diamine, N-
Myristyl butylene diamine, N-myristyl isobutylene diamine, N-cetyl ethylene diamine, N-cetyl propylene diamine, N-cetyl butylene diamine,
N-cetylisobutylenediamine, N-oleylethylenediamine, N-oleylpropylenediamine, N-oleylbutylenediamine, N-oleylisobutylenediamine, N-isostearylethylenediamine, N-isostearylpropylenediamine, N-isostearylbutylenediamine, N -Isostearylisobutylenediamine, etc., or a mixture of two or more thereof.

The amount of the alkylalkylenediamine added is 1
When the amount is less than wt%, the potential of the oil particles is low, so that the repulsion between the oil particles is weak, and the abrasion powder becomes viscous oil such as scum and floats, and it takes time to re-emulsify. By setting the content to 1 wt% or more, an effective potential can be generated for floating the oil particles. However, when the content exceeds 5 wt%, the floating becomes difficult because the oil particles become small. Therefore, the addition amount of the alkylalkylenediamine is set to 1 wt% or more and 5 wt% or less.

The addition of an organic acid having 6 to 10 carbon atoms facilitates floating and re-emulsification of oil particles. That is,
Since the charge of the organic acid is-(negative), it is emphasized that the potential of the alkylalkylenediamine in the oil particles is + (positive), and a large repulsive force is obtained between the oil particles. However, the amount of the organic acid is 1 mole of the alkylalkylenediamine in a molar ratio.
If it is less than / 15, the amount of the organic acid is insufficient, and if it exceeds 1/7, the amount of the organic acid is too large, and no effective repulsion between oil particles can be obtained. If the carbon number of the organic acid is less than 6, there is a disadvantage that the heat resistance of the emulsion is lowered. If the carbon number exceeds 10, a negative charge is hardly generated in water, and the repulsive force between the oil particles is reduced.

Organic acids having 6 to 10 carbon atoms include fatty acids such as n-hexylic acid, 2-ethylhexylic acid, n-octylic acid, isooctylic acid, nonylic acid, isodecylic acid and decylic acid, and aromatic acids such as benzoic acid and salicylic acid. Family acids, adipic acid,
A dibasic acid such as azelaic acid and a tribasic acid such as trimellitic acid or a mixture of two or more thereof can be used.

By adding a nonionic emulsifier to the above rolling oil, the initial emulsifiability of an oil-in-water emulsion can be improved by adding an alkylalkylenediamine and an organic acid to the base oil. Since the nonionic emulsifier is nonionic, the charge formation of the oil particles by the cationic emulsifier is not hindered.

The nonionic emulsifier is not particularly limited, but may be an ethylene oxide adduct of an alkyl phenol,
Fatty acids, ethylene oxide adducts of polyhydric alcohol esters of fatty acids, fatty acid esters of sorbitol and sorbitan, higher alcohols and the like can be used.

Next, the pH of the emulsion was adjusted to 6.5 to 6.5.
The reason for the weak acidity of 4.5 will be explained. As shown in FIG. 1, when the pH of an emulsion obtained by adding a cationic emulsifier to a base oil is set to a weak acidity of 6.5 or less and 4.5 or more, the surface potential of the oil particles is + (positive). The potential of the mixed wear powder also becomes + (positive), and the wear powder and the oil particles are repelled electrically, so that the attachment of the wear powder to the oil particles can be suppressed. Therefore, an emulsion with less wear powder can be obtained.

Even when the pH is less than 4.5, the attachment of wear powder to oil particles can be suppressed, but the acidity becomes high, and safety and corrosion of steel plates and equipment become problems. If it exceeds 6.5, the wear component and the electrical repulsion of the oil particles become weak. The pH can be adjusted by adding the above-mentioned organic acid, but may be further adjusted by adding a fatty acid, a phosphoric acid ester or the like.

The stock solution of the rolling oil of the present invention may contain, as optional components, general-purpose oiliness improvers, extreme pressure additives, antioxidants and the like in addition to the components specified in the present invention. Rolling oil is manufactured by diluting the stock solution with water as before.
Stir to form an emulsion. The concentration of the emulsion is desirably about 2 to 10 vol%.

Next, the rolling method using the cold rolling oil of the present invention will be described by way of an example of separating into two types of emulsions having different concentrations.

FIG. 2 is a conceptual diagram showing an embodiment of the rolling method of the present invention. As shown in FIG. 2, the separation tank 1 has an A tank and a B tank.
The tank is divided into three tanks, a tank and a C tank, and has a structure in which a lower part of the A tank and the lower part of the B tank are connected. The supply pipe 4 is connected.

The rolling oil flowing into the A tank from the rolling mill 3 is
The oil particles float and separate into an upper emulsion with a higher concentration and a lower emulsion with a lower concentration. The upper emulsion flows into the B tank from the upper part of the A tank, and is separated into an upper emulsion having a higher concentration and a lower emulsion having a lower concentration in the B tank. The emulsion in the upper layer having a high concentration in the tank B flows into the tank C, and is sent to the concentration controller 2 from a pipe provided in a lower part of the tank C. On the other hand, the lower emulsion in the A tank and the B tank is sent to the concentration controller 2 from a pipe provided in the lower part of the A tank. Either a high-concentration emulsion (high-concentration emulsion) or a low-concentration emulsion (low-concentration emulsion) sent to the density controller is supplied to a rolling mill to perform rolling. Or,
The high-concentration emulsion and the low-concentration emulsion may be mixed at a predetermined ratio according to the concentration suitable for rolling and the oil particle diameter and supplied to a rolling mill.

By separating the rolling oil in this way,
A high-concentration emulsion having a concentration of about 1.5 to 3 times and an average oil particle diameter of about 1.3 to 2.5 times and a concentration of about 1/3 to 2/3 times that of the rolling oil before separation. , Average oil particle size is 1
A low concentration emulsion of about / 2 to 3/4 times can be obtained.
The concentration and the distribution of the oil particle diameter can be changed by adjusting the mixing ratio of the emulsion with a concentration adjuster.

The high-concentration emulsion has large oil particles, a small amount of abrasion powder, and is extremely excellent in lubricity. Therefore, the high-concentration emulsion is used for rolling ultra-thin materials such as high-carbon steel sheets, austenitic stainless steel sheets and low-carbon steel sheets requiring high lubrication. When used in such a case, the rolling load is reduced, the rolling reduction is increased, and the rolling efficiency can be increased.

The low-concentration emulsion is suitable for gloss rolling because the oil particles are fine and the amount of abrasion powder is small, so that the amount of adhering oil when used for rolling is extremely small.
When the second rolling oil of the present invention is used for rolling a ferritic stainless steel sheet, a high value can be maintained without reducing the surface gloss after rolling even at a high speed of 400 mpm or more. In addition, it is possible to prevent slippage at the time of rolling a medium-thick material of a low carbon steel sheet.

The present invention can be applied to any of a tandem rolling mill and a reversing rolling mill.
By separating rolling oil of one type into emulsions having different concentrations, rolling of various materials becomes possible.

[0051]

(Example 1) Rolling oils (invention examples: 20 types, comparative examples: 13 types) were prepared as emulsions having compositions and properties shown in Tables 1 to 5 and having a concentration of 3 vol% and 7 vol%. Each of the rolling oils was separated into an upper layer emulshun and a lower layer emulsion in the manner shown in FIG. In addition, the rolling oil No. of the comparative example. A5, A8, B3,
For B5, dioctylamine was added to adjust the properties of the rolling oil to the alkali side.

[0052]

[Table 1]

[0053]

[Table 2]

[0054]

[Table 3]

[0055]

[Table 4]

[0056]

[Table 5]

In FIG. 2, the capacity of the separation tank 1 is A tank: 1
20 liters, tank B: 200 liters, tank C: 80 liters, the supply of the emulsion from the lower part of tanks A and C to the rolling mill 3 was 30 liters / min and 30 mi.
After circulating for n times, the emulsion was sampled through the sampling hole 5 provided in the pipe 4, and the emulsion concentration, oil particle diameter and wear powder concentration were measured, and the characteristics of the emulsion were investigated. The wear powder was added at the start of the experiment so that the concentration became 200 ppm. The results of the survey are shown in Tables 6-9.

[0058]

[Table 6]

[0059]

[Table 7]

[0060]

[Table 8]

[0061]

[Table 9]

As shown in Tables 6 to 9, in all of the examples of the present invention, the difference in emulsion concentration between the upper layer and the lower layer was 2% or more and the average particle diameter difference was 2.4 μm or more. When the difference in concentration was less than 1%, the difference in average particle diameter was less than 1 μm.

(Example 2) Tables 6 and 7 obtained in Example 1
The emulsions of the upper layer and the lower layer of each of the inventive examples a1 to a12 and comparative examples A1 to A8 shown in FIG.
The material having a surface roughness Ra of 0.25 μm is supplied to a two-high rolling mill having a work roll of SUJ-2 (bearing steel),
Low carbon steel sheet, high carbon steel sheet (tensile strength: 70 kg / mm
² ) and thickness for SUS304 stainless steel plate:
After hot rolling of 3.2 mm, width: 100 mm, and length: 500 m, the pickling material was rolled. Low carbon steel sheet, high carbon steel sheet (tensile strength: 70 kg / mm ² ) and SUS304
Tables 10, 11, and 1 show the rolling conditions of the stainless steel sheet, respectively.
It is shown in FIG. In addition. Only the lower emulsion was used when rolling the low carbon steel sheet, and only the upper emulsion was used when rolling the high carbon steel sheet and the SUS304 stainless steel sheet.

[0064]

[Table 10]

[0065]

[Table 11]

[0066]

[Table 12]

The surface properties (seizure, uneven gloss, gloss) of the steel sheet obtained by the above rolling and the rolling load were examined. Tables 13 and 14 show the evaluation results of the low carbon steel sheet, Tables 15 and 16 show the high carbon steel sheet, and Tables 17 and 18 show the evaluation results of the SUS304 stainless steel sheet as shown in Table 19.

[0068]

[Table 13]

[0069]

[Table 14]

[0070]

[Table 15]

[0071]

[Table 16]

[0072]

[Table 17]

[0073]

[Table 18]

[0074]

[Table 19]

As shown in Tables 15 to 18, in the examples of the present invention, the rolling load of the high-carbon steel and SUS304 can be reduced with the emulsion of the upper layer significantly reduced as compared with the comparative example. As shown in the figure, it was found that low-carbon steel can be rolled with the lower layer emulsion having the same good surface properties as the comparative example.

Example 3 The upper and lower emulsions of Examples b5 to b8 of the present invention and Comparative Examples B4 and B5 shown in Table 7 obtained in Example 1 each had a diameter of 100 mm and a surface roughness of Ra0. It is supplied to a four-high rolling mill having a work roll of 13 μm of material SKD11 and a backup roll having a diameter of 350 mm, and for stainless steel plates of SUS430 and SUS304, thickness: 3.2 mm, width: 10
After hot rolling of 0 mm and a length of 500 m, the annealed pickling material was rolled. Tables 20 and 21 show the rolling conditions of SUS430 and SUS304 stainless steel plates, respectively. Note that S
When rolling US430 material, only the lower emulsion was used, and when rolling SUS304 material, only the upper emulsion was used.

[0077]

[Table 20]

[0078]

[Table 21]

The surface properties (seizure, uneven gloss, gloss) of the steel sheet obtained by the above rolling and the rolling load were examined. Tables 22 and 23 show SUS430 and SUS30, respectively.
Table 19 shows the evaluation results of the stainless steel sheet No. 4. However, the degree of reduction in the average rolling load was based on Comparative Example 26 in Table 22 and Comparative Example 28 in Table 23.

[0080]

[Table 22]

[0081]

[Table 23]

As shown in Tables 23 and 24, in the examples of the present invention, the SUS 30
4 was possible, and it was found that SUS430 could be rolled while securing a higher glossiness than the comparative example with the lower emulsion.

[0083]

According to the present invention, using one type of rolling oil emulsion, steel sheets having different finish thickness, workability, and surface gloss such as low carbon steel sheet, high carbon steel sheet, and stainless steel sheet are used for each material. It is possible to maintain the corresponding excellent surface quality and to perform high-efficiency rolling.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the pH of an emulsion when an emulsifier is added to a base oil and the potential of oil particles and abrasion powder in the emulsion.

FIG. 2 is a conceptual diagram showing an example of an embodiment of the method of the present invention.

[Explanation of symbols]

 1: separation tank, 2: concentration controller, 3: rolling mill, 4: piping, 5: sampling port.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Hideo Yamamoto 4-53, Kitahama, Chuo-ku, Osaka City Inside Sumitomo Metal Industries Co., Ltd. (72) Keiji Matsumoto 4-5-33, Kitahama, Chuo-ku, Osaka City Sumitomo Metal Industries, Ltd. F term (reference) 4H104 AA01C AA01Z BB16C BB18C BB22C BB23C BB24C BE03C DA02A DA06A EB02 EB14 LA03 LA20 PA26 PA28 PA34 QA03 RA06

Claims (3)

[Claims] 1. A base oil comprising a synthetic ester alone or a mixture of a synthetic ester and a mineral oil or fat or oil, containing 1 to 5% by weight of N-monoalkyl or N-monoalkenyldiamine represented by the formula (1) and carbon number A cationic emulsifier obtained by mixing an organic acid having a molecular weight of 6 to 10 with respect to the N-monoalkyl or N-monoalkenyldiamine at a molar ratio of 1/7 to 1/15, and a nonionic emulsifier of 1 to 5 wt%. It consists of an oil-in-water emulsion obtained by diluting the contained stock solution with water, and the pH of the emulsion is 6.5 to 4.
5. Cold-rolling oil characterized by being 5. Embedded image 2. A base oil comprising a mixture of a monoester and a mineral oil, 1 to 5 wt% of an N-monoalkyl or N-monoalkenyldiamine represented by the formula (1) and a carbon number of 6-1.
A stock solution containing a cationic emulsifier obtained by mixing an organic acid of 0 with the N-monoalkyl or N-monoalkenyldiamine at a molar ratio of 1/7 to 1/15, and 1 to 5% by weight of a nonionic emulsifier Of an oil-in-water type emulsion diluted with water, and the pH of the emulsion is 6.5.
Cold-rolling oil, characterized by being 4.5 to 4.5. Embedded image 3. The cold rolling oil according to claim 1 or 2 is separated into rolling oils of a plurality of emulsions having different concentrations, and one of the separated rolling oils or the separated rolling oils is mixed at a predetermined ratio. A method for rolling a steel sheet, comprising supplying rolling oil onto a steel sheet to be rolled to perform rolling.