Cold-rolled oil composition

Abstract

To provide a cold rolling oil composition that can reduce the particle size in the emulsion state to 1 μm or less, has a high gloss on the surface of the steel sheet after rolling, does not produce patterns due to mottling, and also has excellent lubricity. [Solution] A cold-rolled oil composition comprising: (A) 100 parts by weight of a base oil selected from the group consisting of mineral oil, oils and fats and synthetic esters; (B) 1 to 30 parts by weight of at least one emulsifier selected from the group consisting of nonionic emulsifiers, cationic emulsifiers and anionic emulsifiers; (C) 1 to 5 parts by weight of a castor oil fatty acid polymer; and (D) a partial ester of a polyhydric alcohol and a monohydric fatty acid having one or more hydroxyl groups, in an amount of 3 times or more by weight of component (C).

Description

Technical Field

[0001] The present invention relates to a cold rolling oil composition used when cold rolling steel plates such as carbon steel plates, stainless steel plates, electromagnetic steel plates, and high-tensile steel plates.

Background Art

[0002] Cold rolling oil is prepared by appropriately combining base oils such as mineral oil, various oils and fats, and synthetic esters with nonionic emulsifiers, anionic emulsifiers, cationic emulsifiers, rust inhibitors, extreme pressure agents, antioxidants, etc., diluting with water, and using it as an emulsion with a predetermined concentration for cold rolling of steel plates.

[0003] In recent years, the standards required for the surface properties of steel plates after rolling have become stricter than before, and it is necessary that the surface of the steel plate after rolling has high gloss and no pattern generation due to motoring. Here, motoring means that when cold rolling is performed, rolling is performed in a state where the thickness of the lubricating oil film is uneven, resulting in a difference in the gloss of the steel plate surface and a pattern that cannot be eliminated even after cleaning.

[0004] [[ID=十九]] Regarding countermeasures against motoring, it has been studied before, and it is well known that it can be suppressed by the instantaneous spread of the oil film (hereinafter this performance is referred to as "wetting spreadability") and the disappearance of the thickness. In order to improve the wetting spreadability, a method of increasing the addition amount of the emulsifier of the rolling oil is common. Also, when the requirement for high gloss of the surface of the steel plate after rolling is higher recently, it is necessary to reduce the particle diameter of the rolling oil in the emulsion state to 1 μm or less. In this case as well, the addition amount of the emulsifier increases. However, there is a problem that increasing the addition amount of the emulsifier deteriorates the lubricity. Also, the higher the gloss of the steel plate, the more conspicuous the pattern due to motoring.

[0005] For steel grades where high gloss after rolling is important, the higher the gloss, the more visible the pattern becomes, making mottling prevention crucial. On the other hand, for steel grades that are difficult to process, excellent lubricity is important. Given this situation, there is a growing demand for cold rolling oil compositions that can roll both steel grades where the surface properties after rolling are important and steel grades where lubricity during processing is important, using the same rolling mill, from a productivity standpoint.

[0006] Patent Document 1 discloses an oil-in-water lubricating fluid for use in cold rolling of steel, wherein the fluid comprises an oil-in-water emulsion having a particle size of 1 μm or less, and consisting of an oil phase and water, the oil phase comprising a branched polymer surfactant, a base oil, an extreme pressure lubrication additive, etc. However, although this lubricating fluid is considered to have high lubricity because the branched polymer surfactant, which has slow dynamic interfacial tension characteristics, provides high interfacial tension under dynamic conditions and provides a thick lubricating film (paragraph

[0034] ), it is considered that it cannot suppress patterns caused by mottling.

[0007] Patent Document 2 discloses a cold-rolled oil composition containing a base oil, (A) a specific emulsifier selected from polyoxyethylene alkyl ethers, polyalkylene glycol monoethers, polyoxyethylene alkylphenol ethers, polyoxyethylene fatty acid esters, etc., and (B) a specific castor oil-based nonionic emulsifier selected from polyoxyethylene castor oil, polyoxyethylene hydrogenated castor oil, polyoxyethylene castor oil ether, polyoxyethylene hydrogenated castor oil ether, etc. However, while this cold-rolled oil composition can produce small-particle emulsions with a particle size of 1 to 3 μm, it is difficult to reduce the particle size to 1 μm or less, and it is difficult to achieve the high gloss properties required in recent years. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Special Publication No. 2012-526183 [Patent Document 2] Japanese Patent Publication No. 2017-110090 [Overview of the project] [Problems that the invention aims to solve]

[0009] The object of the present invention is to provide a cold rolling oil composition that can reduce the particle size in the emulsion state to 1 μm or less, has a high gloss on the surface of the steel sheet after rolling, does not produce patterns due to mottling, and also has excellent lubricity.

[0010] Another object of the present invention is to provide a cold rolling oil composition that offers high productivity, since it allows steel grades where the surface properties after rolling are important and steel grades where lubricity during processing is important to be rolled in the same rolling mill. [Means for solving the problem]

[0011] The inventors diligently conducted research to achieve the above objectives and discovered that by blending a castor oil fatty acid polymer together with an emulsifier in the base oil, the particle size of the emulsion particles can be reduced while suppressing the amount of emulsifier added, and the surface of the steel sheet after rolling can be made highly glossy. Furthermore, by blending a partial ester, which is a partial ester of a polyhydric alcohol and a monohydric fatty acid and has one or more hydroxyl groups, mottling can be suppressed even with high gloss. Based on these findings, the inventors further diligently investigated and found that the above objectives can be achieved by blending an emulsifier, a castor oil fatty acid polymer, and the above partial ester in specific proportions in a specific base oil, thus completing the present invention.

[0012] The present invention provides the following cold-rolling oil composition.

[0013] 1. (A) 100 parts by weight of a base oil which is at least one selected from the group consisting of mineral oil, oils and fats and synthetic esters, (B) 1 to 30 parts by weight of at least one emulsifier selected from the group consisting of nonionic emulsifiers, cationic emulsifiers, and anionic emulsifiers. (C) 1 to 5 parts by weight of castor oil fatty acid polymer, and (D) A partial ester of a polyhydric alcohol and a monohydric fatty acid, wherein the partial ester having one or more hydroxyl groups is 3 times or more by weight of component (C). A cold-rolling oil composition containing this oil.

[0014] 2. The cold-rolled oil composition according to item 1 above, wherein the degree of polymerization of the castor oil fatty acid polymer (C) is 2 to 8.

[0015] 3. The cold-rolled oil composition according to item 1 above, wherein the hydroxyl value of the partial ester (D) is 30 to 800 mg KOH / g.

[0016] 4. The cold-rolled oil composition according to item 1 above, wherein the amount of emulsifier (B) added is 8 to 20 parts by weight per 100 parts by weight of base oil.

[0017] 5. The cold-rolled oil composition according to item 1 above, wherein the amount of partial ester (D) added is 3 times or more and 10 times or less by weight of component (C). [Effects of the Invention]

[0018] The cold-rolling oil composition of the present invention exhibits the following remarkable effects.

[0019] (1) The cold rolling oil composition of the present invention can reduce the average particle size of the emulsion particles to 1 μm or less when it is emulsified and dispersed in water to form an emulsion, thereby ensuring high gloss on the surface of the steel sheet after rolling. Furthermore, even with high gloss, it can suppress the formation of patterns due to mottling, and moreover, it can reduce the amount of emulsifier added, thus providing excellent lubricity.

[0020] As described above, the reason why motoring can be suppressed even when the rolled steel sheet has a high gloss is considered as follows. That is, the cold rolling oil using an emulsion is stirred with dilution water in a coolant tank, adjusted to a target concentration, and then applied to the steel sheet using a spray or the like. In the case of a tandem mill, except for the final stand, and in the case of a reversing mill, except for the final pass, since it passes through the rolling rolls again, the emulsion remaining on the steel sheet causes evaporation of moisture due to processing heat and frictional heat, becoming denser than the concentration in the coolant tank. Whether this concentrated emulsion mixes instantaneously with the emulsion supplied from the spray when passing through the next rolling roll is considered to influence the occurrence of motoring. Here, in the cold rolling oil composition of the present invention, by blending a specific amount of a partial ester of a polyhydric alcohol and a monohydric fatty acid as the component (D), which is a partial ester having one or more hydroxyl groups, it is possible to instantaneously mix the concentrated emulsion and the emulsion supplied from the spray, making it easier to form a uniform oil film, and thus it is considered that the occurrence of motoring can be suppressed.

[0021] (2) Further, since the cold rolling oil composition of the present invention is excellent in the lubricity of the emulsion, by using this, it is possible to increase productivity in terms of being able to roll steel grades important for the surface properties after rolling and steel grades important for the lubricity during processing on the same rolling mill.

Embodiments for Carrying Out the Invention

[0022] Cold-rolled oil composition The cold rolling oil composition of the present invention is It is characterized by containing (A) a base oil selected from the group consisting of mineral oil, oils and fats and synthetic esters, (B) an emulsifier selected from the group consisting of nonionic emulsifiers, cationic emulsifiers and anionic emulsifiers, (C) a castor oil fatty acid polymer, and (D) a partial ester of a polyhydric alcohol and a monohydric fatty acid having one or more hydroxyl groups, and furthermore, by containing each in specific proportions of (B) at 1 to 30 parts by weight, (C) at 1 to 5 parts by weight, and (D) at 3 times the weight of (C) at least per 100 parts by weight of (A).

[0023] The cold rolling oil composition of the present invention forms an O / W type emulsion in which oil droplets are dispersed in water by emulsifying and dispersing it in water to a concentration of about 1 to 20% by volume. This emulsion is a fine particle size emulsion with excellent emulsification stability, and the average particle size of the emulsion particles is usually 1.0 μm or less. By using such an emulsion, the surface of the steel sheet after rolling will have high gloss, be free from pattern formation due to mottling, and also have excellent lubricity. Here, the average particle size of the emulsion particles is usually the average particle size measured with a laser particle size distribution analyzer.

[0024] Base oil (A) As the base oil (A) used in the present invention, any of those conventionally used in this type of rolling oil composition can be used. Specifically, at least one selected from the group consisting of mineral oil, oils and fats, and synthetic esters can be used. Examples of mineral oils include spindle oil, machine oil, turbine oil, cylinder oil, etc. Examples of oils and fats include animal and vegetable oils such as whale oil, beef tallow, lard, rapeseed oil, castor oil, rice bran oil, palm oil, and coconut oil. Examples of synthetic esters include monoesters of fatty acids and / or synthetic fatty acids obtained from beef tallow, castor oil, coconut oil, etc., and aliphatic monohydric alcohols having 8 to 18 carbon atoms; and full esters of the above fatty acids and / or synthetic fatty acids and polyhydric alcohols such as polyethylene glycol, neopentyl glycol, trimethylolpropane, pentaerythritol, and dipentaerythritol.

[0025] Emulsifier (B) The emulsifier (B) used in this invention is added to reduce the particle size of the emulsion and to improve the wetting spreadability when it becomes an emulsion. Any emulsifier that has been conventionally used in this type of rolling oil composition can be used. Specifically, one or more types of nonionic, cationic, and anionic emulsifiers can be used in appropriate combinations, selected according to the required performance such as iron powder dispersibility and rust prevention.

[0026] Examples of nonionic emulsifiers among emulsifiers (B) include polyoxyalkylene alkyl ethers, polyalkylene glycol monoethers, polyoxyalkylene alkylphenyl ethers, polyoxyethylene fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitol fatty acid esters, polyoxyethylene castor oil, polyoxyethylene hydrogenated castor oil, polyoxyethylene castor oil ethers, and polymer adducts obtained by adding polyoxyethylene to polycondensed castor oil.

[0027] Examples of cationic emulsifiers among emulsifiers (B) include alkylpyridinium chloride, alkyltrimethylammonium salt, dialkyldimethylammonium chloride, quaternary ammonium salt having polyalkylene oxide, alkyldiamine having polyalkylene oxide, and fatty acid amide alkylamine having polyalkylene oxide.

[0028] Furthermore, among the emulsifiers (B), anionic emulsifiers include, for example, sodium alkyl sulfonate, sodium alkylbenzene sulfonate, and sodium naphthenate.

[0029] The amount of emulsifier (B) added is approximately 1 to 30 parts by weight, preferably 8 to 20 parts by weight, per 100 parts by weight of base oil. If the amount added is less than 1 part by weight, it is difficult to obtain the desired average particle size, and if the amount added exceeds 30 parts by weight, the lubricity of the cold-rolled oil composition is impaired.

[0030] Castor oil fatty acid polymer (C) The inventors have discovered that by incorporating a specific amount of castor oil fatty acid polymer (C), it is possible to reduce the particle size of the emulsion even when the amount of emulsifier added is suppressed. Since a high degree of polymerization of castor oil fatty acid polymer (C) reduces its emulsifying and dispersible properties, a degree of polymerization of 2 to 8 is preferable, and a degree of polymerization of 2 to 6 is more preferable.

[0031] The amount of castor oil fatty acid polymer (C) added is approximately 1 to 5 parts by weight per 100 parts by weight of base oil. If the amount added is less than 1 part by weight, it is difficult to obtain the target particle size, and if it is added in excess of 5 parts by weight, it reduces the effect based on partial ester (D) that causes the concentrated emulsion on the steel plate and the emulsion supplied from the spray to mix instantaneously, making it difficult to form a uniform oil film.

[0032] A partial ester of a polyhydric alcohol and a monohydric fatty acid, the partial ester having one or more hydroxyl groups (D) While the addition of castor oil fatty acid polymer (C) tends to reduce emulsification and dispersibility, making emulsion formation difficult, the inventors have discovered that by adding a partial ester (D), which is a partial ester of a polyhydric alcohol and a monohydric fatty acid and has one or more hydroxyl groups, in an amount of 3 times or more by weight of the castor oil fatty acid polymer (C), the concentrated emulsion on the steel sheet and the newly supplied emulsion from the spray mix instantaneously, and mottling can be suppressed even if the steel sheet has high gloss after rolling. If the amount of partial ester (D) added is less than 3 times by weight, the effect of instantaneous mixing between the concentrated emulsion and the emulsion supplied from the spray decreases, causing mottling. Preferably, the amount of partial ester (D) added is 4 times or more by weight of the castor oil fatty acid polymer (C). There is no particular upper limit to the amount of partial ester (D) added, but usually, from a cost standpoint, it is preferable to be 10 times or less by weight of the castor oil fatty acid polymer (C).

[0033] Partial ester (D) is obtained by esterifying a polyhydric alcohol and a monohydric fatty acid in a molar ratio such that one or more hydroxyl groups of the polyhydric alcohol remain. The hydroxyl value, which is an indicator of the hydroxyl group content of partial ester (D), is preferably about 30 to 800 mgKOH / g, and more preferably about 50 to 500 mgKOH / g.

[0034] As the polyhydric alcohol used as the raw material for partial ester (D), any of those conventionally used in ester synthesis can be used. Examples include ethylene glycol, glycerin, trimethylolpropane, pentaerythritol, and dipentaerythritol. As the monounsaturated fatty acid, linear or branched saturated or unsaturated monounsaturated fatty acids with approximately 6 to 22 carbon atoms can be used. Specifically, examples include ethylene glycol monooleate, glyceryl dioleate, trimethylolpropane dioleate, and pentaerythritol dioleate.

[0035] Other ingredients In addition to a base oil (A), emulsifier (B), castor oil fatty acid polymer (C), and partial ester (D), the rolling oil composition of the present invention may further contain, as needed, various known additives such as extreme pressure agents, oiliness improvers, antioxidants, rust inhibitors, oil burn inhibitors, lubricating additives, pH improvers, defoaming agents, wettability improvers, and the like.

[0036] Examples of extreme pressure agents include tricresyl phosphite, zinc dialkyldithiophosphate, and sulfurized oils and fats. Examples of oiliness improvers include fatty acids such as oleic acid, stearic acid, and dimer acid, and trimethylolpropane fatty acid condensate esters. Examples of antioxidants include phenolic compounds such as 2,4-di-t-butyl-p-cresol and aromatic amines such as phenyl α-naphthylamine. Examples of rust inhibitors include fatty acids such as oleic acid, esters such as sorbitan monooleate, alkylaminocarboxylic acid, and alkenyl succinic acid, and cyclohexylamine EO adducts. Examples of pH improvers include amine-based compounds such as monoethanolamine, diethanolamine, and triethanolamine. Examples of defoaming agents include emulsion-type silicone oil and mixtures of metal soap and PEG-type nonionic surfactants. Examples of wettability improvers include aliphatic alcohols. [Examples]

[0037] The present invention will be described more specifically below based on examples and comparative examples, but the present invention is not limited in any way by these examples.

[0038] Examples 1-2 and Comparative Examples 1-7 The cold-rolled oil compositions of the present invention and for comparison were prepared using the components shown in Table 1 below.

[0039] [Table 1]

[0040] In Table 1, all values ​​for each composition are expressed in parts by weight. The components in Table 1 are as follows:

[0041] Mineral oil: Paraffin-based refined mineral oil (viscosity: 40 mm) 2 / s) Synthetic ester: Octyl myristate Oils and fats: Palm oil

[0042] Emulsifier 1: Nonionic surfactant; 2-ethylhexyl diglycol Emulsifier 2: Anionic surfactant; sodium petroleum sulfonate Emulsifier 3: Nonionic surfactant; polyoxyalkylene ether (HLB=8~9) Emulsifier 4: Nonionic surfactant; polyoxyethylene dodecylphenyl ether (number of moles of ethylene oxide (EO) added: 5-6) Emulsifier 5: Nonionic surfactant; polyoxyethylene hydrogenated castor oil (EO addition moles: 20-30)

[0043] Castor oil fatty acid polymer (degree of polymerization: approximately 4)

[0044] Partial ester: Pentaerythritol oleic acid half-ester (number of hydroxyl groups: 2 per molecule, hydroxyl value: 150-200 mg KOH / g)

[0045] Alkenyl succinic acid (acid value: 194 mg KOH / g)

[0046] Next, the average particle size, lubricity, and presence or absence of pattern formation were investigated for each cold-rolled oil composition of the present invention and for comparison using the following method.

[0047] Average particle size The evaluation was performed using an emulsification test with a circulation pump. 5 liters of tap water were added to the tank as dilution water and heated using a heater. After maintaining the temperature at 50-55°C, each cold-rolled oil composition was added to a total volume of 5%. Circulation pump (nozzle part number: 1 / 4EX424, spray pressure: 1.0 kgf / cm²)2 The diluted water and rolling oil composition are circulated for 15 minutes using a circulating solution to form an emulsion, after which the average particle size is measured.

[0048] The average particle size (μm) of the emulsion was measured using a laser particle size distribution analyzer (SALD-2300 LASER DIFFRACTION PARTICLE SIZE ANALYZER, manufactured by Shimadzu Corporation). The average particle size was evaluated as follows: ○ for 1.0 μm or less (good) and × for greater than 1.0 μm (bad).

[0049] Lubricity Lubricity was evaluated by rolling steel plates (steel type: SPHC) using a 2Hi Bright rolling mill (roll diameter Φ: 120~200 mm, rolling speed: 10 m / m) with rolls polished with #240 sandpaper. First, 5 L of tap water was added to a tank as dilution water and heated using a heater. After maintaining the temperature at 50~55°C, each cold rolling oil composition was added to a total volume of 5%. Then, a circulation pump (nozzle part number: 1 / 4EX424, spray pressure: 1.0 kgf / cm²) was used. 2 An emulsion was created by circulating the dilution water and rolling oil composition for 15 minutes using a sprayer. Once the emulsion was complete, it was supplied to each roll by spraying, and rolling was performed with the emulsion supplied to both sides of a 2.3mm x 20mm x 250mm steel plate (steel type: SPHC) via the rolls. The rolling was carried out in 5 passes, with a total reduction ratio of approximately 77%.

[0050] During rolling, the load P (tons) for each pass was measured using a load cell, and the thickness (mm) of the steel plate before and after rolling was measured. Based on these measurement results, the total load (tonf / mm) was calculated using the following formula. Total load = ΣP / Δh Here, in the formula, ΣP is the sum of the loads P in each pass, and Δh is the difference between the steel sheet thickness before rolling and the final steel sheet thickness. Therefore, ΣP / Δh is the total load required to thin the steel sheet by 1 mm, and a smaller value indicates better lubricity. Lubricity was evaluated as follows: a total load of less than 24 was good (○), and a total load of greater than 24 was poor (×).

[0051] Presence or absence of pattern formation As part of the evaluation of the motling process, a pattern reproduction test was conducted using the following method. The pattern reproduction test was performed by rolling a steel plate (steel type: SPHC) using a 2Hi bright rolling mill (roll diameter Φ: 120~200 mm, rolling speed: 10 m / m) with rolls polished with #240 sandpaper. First, 5 L of tap water was added to the tank as dilution water and heated using a heater. After maintaining the temperature at 50~55°C, each cold rolling oil composition was added to a concentration of 5% by volume. Then, a circulation pump (nozzle part number: 1 / 4EX424, spray pressure: 1.0 kgf / cm) was used. 2 An emulsion was prepared by circulating the dilution water and rolling oil composition for 15 minutes using a sprayer. Once the emulsion was complete, it was supplied to each roll by spraying, and rolling was performed with the emulsion supplied to both sides of a 2.3mm x 50mm x 250mm steel plate (steel type: SPHC) via the rolls.

[0052] First, the steel sheet was rolled in 6 passes with a total reduction ratio of approximately 69%, and the emulsion on the steel sheet surface and roll surface was wiped off with a dry cloth. Then, while supplying emulsion again, one pass rolling was performed with a reduction ratio of 28%, and after cleaning the surface with n-hexane, the presence or absence of patterns due to differences in gloss on the steel sheet surface was observed. The evaluation of the presence or absence of patterns was rated as "good" (○) if there were no patterns larger than 5 mm, and "bad" (×) if there were patterns larger than 5 mm.

[0053] The results of the investigation into average particle size, lubricity, and the presence or absence of pattern formation are shown in Table 2 below.

[0054] [Table 2]

[0055] As shown in Table 2, Examples 1 and 2, by using castor oil fatty acid polymers, were able to reduce the amount of emulsifier added while keeping the average particle size below 1 μm. The ease of emulsification and dispersion, which is worsened by castor oil fatty acid polymers, can be ensured by the partial ester, which is a partial ester of a polyhydric alcohol and a monohydric fatty acid having one or more hydroxyl groups, thus ensuring lubricity while suppressing pattern formation. On the other hand, Comparative Examples 1 and 4 have a large amount of emulsifier, so although the average particle size is small, close to 1 μm, the lubricity is poor. Comparative Examples 2, 3, and 5 all have a large average particle size because the amount of emulsifier was reduced. Comparative Example 6 has a pattern because only 2 times the weight of the partial ester, which is a partial ester of a polyhydric alcohol and a monohydric fatty acid having one or more hydroxyl groups, is added to the castor oil fatty acid polymer. Comparative Example 7 does not have an average particle size below 1 μm because the amount of castor oil fatty acid polymer added is small. [Industrial applicability]

[0056] The present invention provides a cold rolling oil composition that can suppress the amount of emulsifier added, maintain lubricity, and suppress the formation of patterns due to mottling. By using this cold rolling oil composition, it becomes possible to meet the demand from a productivity standpoint to roll steel types where the surface properties after rolling are important and steel types where lubricity during processing is important in the same rolling mill, and therefore it is suitably used in the cold rolling of steel sheets.

Claims

1. (A) 100 parts by weight of a base oil which is at least one selected from the group consisting of mineral oil, oils and fats and synthetic esters, (B) 1 to 30 parts by weight of at least one emulsifier selected from the group consisting of nonionic emulsifiers, cationic emulsifiers, and anionic emulsifiers. (C) 1 to 5 parts by weight of castor oil fatty acid polymer, and (D) A partial ester of a polyhydric alcohol and a monohydric fatty acid, wherein the partial ester having one or more hydroxyl groups is three times or more by weight of component (C). A cold-rolling oil composition containing this oil.

2. The cold-rolled oil composition according to claim 1, wherein the degree of polymerization of the castor oil fatty acid polymer (C) is 2 to 8.

3. The cold-rolled oil composition according to claim 1, wherein the hydroxyl value of the partial ester (D) is 30 to 800 mg KOH / g.

4. The cold-rolled oil composition according to claim 1, wherein the amount of emulsifier (B) added is 8 to 20 parts by weight per 100 parts by weight of base oil.

5. The cold-rolled oil composition according to claim 1, wherein the amount of partial ester (D) added is 3 to 10 times the weight of component (C).

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