KR20090118604A - Water soluble cold rolling oil for decreasing formation of scum - Google Patents

Abstract

PURPOSE: A water-soluble cold rolling oil composition is provided to ensure high contamination resistance, lubrication, and heat dispersion. CONSTITUTION: A water-soluble cold rolling oil composition comprises 40-60 weight% of synthetic ester with 30-100 mm/s of viscosity, 10-30 weight% of vegetable natural oil, 10-30 weight% of fixing agent mineral oil, 1.7-5.5 weight% of emulsifier, 3-7 weight% of extreme pressure additive, 1-3 weight% of lubrication enhancer, and 0.3-2.0 weight% of additive selected from a group of antioxidant, corrosion inhibitor and microorganism inhibitor.

Description

WATER SOLUBLE COLD ROLLING OIL FOR DECREASING FORMATION OF SCUM}

The present invention relates to a water-soluble cold rolled oil composition used for rolling general steel, automotive steel sheet and high-tensile steel sheet, in particular, high-speed wide automotive steel sheet, and more particularly, has good lubricity, less scum, and excellent stain resistance. It is related with the water-soluble cold rolling oil composition which can improve the surface quality of the.

The conventional water-soluble cold rolled oil for general cold rolled steel sheet is a lubricant additive, an extreme pressure agent, an emulsifier, an antioxidant, a corrosion inhibitor, and a microbial growth inhibitor for a synthetic fatty acid and a synthetic ester in a base oil (base oil), which is generally composed of synthetic esters, animal and vegetable oils, mineral oils, and the like. And the like is added.

The conventional cold rolled oil thus constructed is diluted in pure water at a temperature of 50 ° C. at a concentration of 5.0% by weight or less in actual field application, prepared in an emulsion state (referred to as “coolant”), and in such an emulsion state. It has been used to circulate coolant. However, the conventional cold rolled oil has a high content of low-viscosity synthetic esters, so that volatile organic substances are generated by heat during rolling reduction and coiling of the exit coil due to frictional heat generated during rolling and pressure conditions per unit area. Since it is easily generated as a fume and diluted with pure water, chemical reactions such as hydrolysis occur and combine with iron generated during rolling operation to generate a large amount of scum, which contaminates the rolling mill and the coolant. As a result, there was a problem that the surface quality of the steel sheet is lowered.

On the other hand, as the production volume of high-grade steel such as automobile steel sheet is increased and the steel sheet surface quality target is raised, the demand for securing the steel sheet surface quality is increasing day by day. Therefore, in order to meet these demands, while developing the primary cold-rolling stability of the rolling oil, while developing a new cold rolling oil that can minimize the contamination of the rolling mill that can cause the steel surface surface contamination and reduce the amount of rolling oil used There is a need.

The present invention solves the above problems, by providing a cold rolled oil composition having excellent pollution resistance characteristics, scum flow characteristics, optimal lubrication characteristics and thermal volatilization properties to make a steel sheet having excellent surface quality For that purpose.

To this end, the present invention is 40 to 60% by weight of a synthetic ester having a viscosity of 30 to 100 mm ² / s; 10-30% by weight of vegetable natural fats and oils; 10-30 weight% of fixative mineral oil; 1.7 to 5.5 weight percent emulsifier; 3-7 wt% of extreme pressure agent; 1 to 3 weight percent of a lubrication improver; And 0.3 to 2.0 wt% of at least one additive selected from the group consisting of antioxidants, corrosion inhibitors and microbial inhibitors.

At this time, the synthetic ester is preferably C ₁₂ ~ C ₁₈ fatty acid hindered ester, the emulsifier is 1.0 to 3.0% by weight polyethylene glycol emulsifier, 0.5 to 1.5% by weight amine salt emulsifier and 0.2 to 1.0 weight of alcohol emulsifier It is preferably made of%.

The cold rolled oil composition of the present invention is superior to the conventional cold rolled oil composition in terms of pollution resistance, scum flow characteristics, lubrication characteristics, and thermal volatilization characteristics. Therefore, when the cold rolled oil composition of the present invention is used, the amount of scum generated with the rolling mill is reduced, the amount of iron attached to the surface of the steel sheet is reduced, the steel sheet reflectivity is improved, and steel sheets having excellent surface quality characteristics can be produced. Can be.

In fact, in the process using the cold rolling oil of the present invention, the amount of scum generated with the rolling mill was reduced by 46% and the steel sheet reflectance was increased by 16% compared with the prior art. In addition, the amount of oil discharged through the Hoffman filter was reduced by 35% and the iron removal amount was increased by 309%. This resulted in a 31% reduction in raw units (= rolling oil consumption / production).

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated more concretely.

The inventors of the present invention have found that by adjusting the composition and composition of the cold rolled oil, it is possible to improve the lubrication and thermal volatilization characteristics of the cold rolled oil, minimize the occurrence of scum, and improve the stain resistance. Was completed.

Cold rolled oil composition of the present invention is a base oil (base oil) consisting of 40 to 60% by weight of synthetic esters having a viscosity of 30 to 100 mm ² / s, 10 to 30% by weight of vegetable natural fats and oils and 10 to 30% by weight of the fixing mineral oil In the mixture of 1.7 to 5.5% by weight of emulsifier, 3 to 7% by weight of extreme pressure agent, 1 to 3% by weight of lubrication enhancer, and 0.3 to 2.0% by weight of one or more additives selected from the group consisting of antioxidants, corrosion inhibitors and microbial inhibitors Is done.

The cold rolled oil composition of the present invention as described above is the total amount of low-viscosity synthetic esters, such as diesters of C ₁₂ ~ C ₁₈ fatty acids used in the prior art as a medium-high viscosity synthetic ester having a viscosity of 30 to 100 mm ² / s Characterized in that replaced.

The synthetic ester used in the present invention is preferably a hindered triester of C ₁₂ to C ₁₈ fatty acids. C ₁₂ ~ C ₁₈ fatty acid ester of a hindered tree is the reaction product of a polyhydric alcohol and straight chain fatty acid having a carbon number C ₁₂ ~ C _18, acts as the base oil component in the rolling oil is to present a high heat stability and oxidation stability.

The content of the synthetic ester of medium-high viscosity is preferably about 40 to 60% by weight based on the total weight of the rolling oil composition. If the content of the medium-high viscosity synthetic ester is less than 40% by weight or more than 60% by weight, there is a problem that the heat resistance and the oxidative stability are lowered and the emulsion may become unstable.

In addition, the present invention can reduce the content of vegetable natural fats and oils in the base oil (base oil) components, increase the content of the fixed mineral oil having excellent flow characteristics, thereby ensuring the oxidation stability of the base oil itself, can improve the flow characteristics of scum It is characterized by what it did.

The vegetable natural fats and oils may be used alone or in combination of one or more selected from the group consisting of palm oil and palm kernel oil, the content is up to 30% by weight, preferably 10 to 30% by weight based on the total weight of the rolling oil composition It is preferable that it is about%. Vegetable natural fats and oils may help the lubrication and degreasing properties as the amount added, but when the content is increased, the oxidation stability and fouling resistance characteristics of the rolling oil is lowered. Therefore, an optimum effect can be obtained when the content of the vegetable natural fat or oil is in the above range.

On the other hand, the fixing agent mineral flow path Precision solvent-purified hydroparaffin distillate can be used, and the content thereof is preferably about 10 to 30% by weight. This is because when the content of the fixative mineral oil is less than 10% by weight or more than 30% by weight, fouling resistance is deteriorated due to emulsion instability.

Additives such as emulsifiers, extreme pressure agents, lubrication enhancers, antioxidants, corrosion inhibitors and microbial growth inhibitors are added to the base oil configured as described above.

The emulsifier is added to weaken the interfacial tension between pure water and oil when the rolled oil is diluted in pure water so that emulsification is possible. In the present invention, polyethylene glycol ester emulsifier and amine system, which were conventionally used as an emulsifier of a rolling oil composition, are used. The emulsifier is characterized by further using an alcoholic ester emulsifier.

Depending on the emulsifier composition and the amount of each addition, the amount of steel plate adhered to the rolled material (plate out property) varies, and thus the rolling lubricity is adjusted. In addition, the particle size and distribution of the coolant formed by the emulsifier affect the rolling operation stability, rolling mill contamination and steel sheet surface quality.

As in the present invention, when the alcohol-based ester emulsifier is mixed with the polyethylene glycol-based and amine salt-based emulsifier, the particle size distribution can be maintained uniformly, the scum generation in the rolling mill can be suppressed, and the cleaning property can be secured. In addition, iron separation is good, which improves the filtration efficiency of the Hoffman filter. In addition, while the amount of oil discharged through the filter is reduced, the amount of rolled oil used is economical.

On the other hand, the emulsifier is preferably added in an amount of 1.7 to 5.5% by weight based on the total weight of the rolling oil. This is because when the content is less than 1.7% by weight or more than 5.5% by weight, the effect of suppressing emulsification instability and scum generation of the rolling oil cannot be obtained.

On the other hand, the polyethylene glycol-based emulsifier and the amine salt-based emulsifier can be used in combination in the amount generally used for those commonly used in water-soluble cold rolling oil. Accordingly, the type and content thereof are not particularly limited, but for example, the polyethylene glycol-based emulsifier is in an amount of about 1.0 to 3.0% by weight based on the total weight of the rolled oil composition, and the amine salt-based emulsifier is the total weight of the rolled oil composition. It may be included in about 0.5 to 1.5% by weight based on. The content of the polyethylene glycol-based emulsifier and the amine salt-based emulsifier may be appropriately adjusted within the range of 1.7 to 5.5% by weight. However, the alcohol ester emulsifier should be included in an amount of about 0.2 to 1.0% by weight based on the total weight of the rolled oil composition. This is because when the content of the alcohol ester emulsifier is less than 0.2 wt% or more than 1.0 wt%, the emulsion stability is lowered.

Next, as the extreme pressure agent, a mixture of a sulfur-based extreme pressure agent and a phosphorus-based extreme pressure agent generally applied to the extreme pressure agent of cold rolled oil may be used. Examples of sulfur-based extreme pressure agents include, but are not limited to, sulfur, fats such as oils, CS, -SS-, -SSS- in aromatic or alkyl groups, such as oils such as fats and oils, dididodecyl trisulfide, and dibenzyl pentasulfide. Extreme pressure agents which have a structure, etc. are mentioned. Examples of phosphorus suppressors include, but are not limited to, aliphatic amine phosphates, aromatic amine phosphates, aromatic diamine phosphates, zinc dithio phosphates, and trialkyl phosphates. phosphate), and the like.

On the other hand, in the use of such extreme pressure agent, due to the influence of the extreme pressure performance supplement by the operating temperature of each extreme pressure agent, a mixture of phosphorus having good low temperature characteristics and sulfur type extreme pressure agent having excellent high temperature characteristics is used. Preferably, it is effective in improving the extreme pressure lubrication activity (fusion point and friction coefficient of the Palex tester), and the total amount of the phosphorus-based and sulfur-based extreme pressure agents is preferably about 3 to 7% by weight based on the total weight of the rolling oil composition. There is a limit to the improvement of the extreme pressure lubrication activity of the cold rolled oil according to the increase of the extreme pressure agent, and when applied in excess of 7% by weight, the emulsion stability of the rolling oil is lowered. Such emulsion instability acts as a deterrent to operational stability.

On the other hand, the lubrication enhancer, but is not limited to this, stearic acid, palm fatty acid, oleic acid, C ₃₀ ~ C ₃₆ dimer acid, acrylated fatty acid ester and the like can be used. On the other hand, the lubrication improver is preferably added in an amount of 1 to 3% by weight based on the total weight of the rolling oil composition. If the content is less than 1% by weight, the effect of improving lubricity is insignificant. If the content is more than 3% by weight, the occurrence of scum is increased by fatty acid stone gum during use of the rolling oil, and the surface quality of the steel sheet is reduced by increasing the coolant contamination. .

On the other hand, as the antioxidant, for example, a phenol-based antioxidant, more specifically, a derivative of diphenylamine is applied, the content is preferably 0.3 to 1.5% by weight based on the total weight of the rolling oil. If the content is less than 0.3% by weight, there is a problem in that the viscosity increases due to oxidation of the rolling oil in the rolling conditions, and the amount of the iron-gum material is increased. When the content is more than 1.5% by weight, the effect is not increased.

Although the microbial growth inhibitor is not limited thereto, for example, it is preferable that the benzoic acid sodium salt derivative is applied at 1% by weight or less based on the total weight of the rolled oil composition. The microbial growth inhibitor suppresses the formation and growth of scum materials formed around the mill during rolling operations, and suppresses corrosion of rolling mills and surroundings by oxidation of iron components contained in the scum. This is because even if the content is added in excess of 1% by weight, the effect is no longer increased.

Meanwhile, corrosion inhibitors may be added in addition to the antioxidants and microbial inhibitors, and additives such as antioxidants, microbial growth inhibitors, and corrosion inhibitors may be about 0.3 to 2.0 wt%.

The cold rolled oil composition of the present invention prepared as described above is used by dilution with pure water at a concentration of less than 1 to 5% by weight when the cold rolling process is applied.

The rolling oil additive of the present invention and the rolling oil composition comprising the same are applicable to the rolling of any steel sheet, and are particularly suitable for rolling automotive steel sheets (and high tensile steel).

Hereinafter, the present invention will be described in more detail with reference to specific examples.

Water-soluble cold rolled oil compositions having the compositions shown in Table 1 were each prepared, and then subjected to extreme pressure lubricity, emulsification stability, fouling resistance, thermal volatilization properties, plate out properties (oil content with steel sheet) and oil staining properties in the manner described in the test examples. Degreasing and the like were measured.

Composition Conventional cold rolled oil composition ratio (wt%) Cold rolled oil composition ratio of the present invention (wt%) Comparative example Example C _{12 -} C ₁₈ diesters 20 - C _{12 -} C ₁₈ Hindered Tree Ester 30 50 Plant Oil (Palm Oil) 30 15 Fixative mineral oil 7 21 Lubrication Enhancer 2 2 Extreme pressure Sulfur extreme pressure agent 5 5 Phosphorus Pressure Reducing Agent One One Emulsifier Grillol Emulsifier 2 2 Amine emulsifier One One Alcohol emulsifier - One Other additives Antioxidant One One Microbial inhibitor 0.4 0.4 Corrosion inhibitor 0.6 0.6

Test Example

(1) FALEX TEST

The lubrication property of each rolling oil composition was measured using the FALEX lubrication tester (manufacturer: Shinko Co., Ltd.). The results are shown in [Table 2] below.

(2) Emulsification stability (measurement of particle size and ESI) and contamination resistance (total contamination adhesion) measurement

Using a 400 ml beaker, the rolling oil compositions of Comparative Examples and Examples were made to a concentration of 2.0 wt% in pure water at 50 ° C., followed by stirring at 3000, 5000, 7500, and 5000 rpm using a homo mixer as shown in FIG. 1, respectively. While measuring, the particle diameter is measured. (After stirring 7500rpm, activated iron was added 3 minutes later (300ppm, 500ppm)). After completion of stirring, an appropriate amount (cacia flask 100 ml) was taken with a measuring cylinder to measure the initial concentration, and the initial concentration was measured.

Emulsion index (ESI-15 ') was added to 200 ml of the same emulsion in a separatory filter and allowed to stand in a thermostat (50 ° C) for 15 minutes. After completion of the test, the coolant in the beaker was emptied and the total amount of fouling adhered to the stirrer and the inner wall of the beaker was measured (by iron content). The measured results are shown in the following [Table 2].

(3) Thermal Gravity Analysis (Thermal Gravity Analysis)

10 mg each of the rolled oil composition prepared in (2) above at a heating rate of 10 ° C./min, N ₂ While heating from 50 ° C. to 600 ° C. in an atmosphere, a temperature-evaporation curve was drawn using a thermogravimetric analyzer (thermo-gravimetric analyzer). The organic matter content% (VOC (Volitile of Carbon)) volatilized below 200 ° C. was measured using a graph curve.

In addition, the temperature when the residual amount was 85% and the volatilization temperature when the residual amount was 15% were measured using the graph curve. And after completion of the test, the residual carbon amount of the final residue was measured. The results are shown in the following [Table 2].

(4) Plate out property test (Measurement of steel plate oil content)

A rolling oil composition of Comparative Example and Example was emulsified in 2 wt% of pure water at 50 ° C. using a circulation tester as shown in FIG. 2, and then circulated for 24 hours. Spray the emulsion for 10 seconds on the specimen (20 mm × 50 mm) produced by spraying the long-term circulation tester. Leave this specimen at room temperature for 24 hours.

The amount of oil adhering to the surface of the specimen was measured and compared by using the surface oil / carbon meter (LECO). The measurement results are shown in [Table 2].

(5) Oil stainability test

Each rolling oil composition of Comparative Example and Example was emulsified to 2 wt% in pure water at 50 ° C, and 0.5 ml was added dropwise to a specimen (SPCC 60 × 80 × 1 to 1.2 mm) prepared by sampling with a pipette. After laminating | stacking using another test piece, it tightens four places in each direction with a blade creep. Place the specimen vertically in a thermostat bath using a creep and cover the lid. After 8 hours, the test piece is removed and it is determined whether oil stain is generated. The measurement results are shown in [Table 2].

(6) degreasing test

Sample oil was prepared by dissolving the rolling oil compositions of Comparative Examples and Examples at 2 wt% in an organic solvent of normal hexane. The clean washed specimen (20 mm x 50 mm) was immersed therein and dried at room temperature for 24 hours, followed by a degreasing test with a degreasing solution. Next, the amount of oil attached to the surface of the specimen was measured and compared using the surface oil / carbon measuring instrument (LECO) before and after degreasing. The measurement results are shown in the following [Table 2].

Degreasing solution-Low temperature complex degreasing agent used in POSCO 4 cold rolling mill (concentration 2%, temperature 50 ℃)

Degreasing method-Ultrasonic degreasing / electrolytic degreasing / washing (pure), time 10 seconds

Test Items Comparative example Example General characteristics Viscosity (40 ° C, mm2 / s) 38 49 Acid value (mgKOH / g) 6 6 Saponification value (mgKOH / g) 205 170 pH (3%, pure) 4.2 5.3 Pollution Resistance (Flow Characteristics) Total contamination Iron 300 ppm 33.4 22.5 Iron 500 ppm 77.6 32.7 Pour point (℃) -5.0 -5.0 Antirust Casting Chip Method 60 minutes 90 minutes Lubrication Characteristics Plate out amount (mg / ㎡) 111 107 FALEX TEST Melting Point (lbs) 2500 3000 Pyrolytic (T.G.A) V.O.C (200 ℃ ↓) 2.1 0.94 Temperature by residual content (85 ~ 15%) 285 ~ 393 312-404 Residual Carbon (mg) 0.34 0.01 Oil painting properties A new sum 3000 rpm, 5 '(μm) 24.3 24.9 Iron input 7500 rpm, 15 '(μm) 7.5 7.5 ESI-15 '(%) 75 78 Etc Oil stain resistance Good Good Degreasing (%) 95.1 95.8

As a result of the evaluation of fouling resistance, it can be seen that when using the rolling oil of the example, the fouling resistance was improved by 33% compared with the case of using the rolling oil of the comparative example.

1 shows a homo mixer tester used in the test of the present invention.

2 shows a cyclic tester used in the test of the present invention.

Claims (9)

40 to 60 weight percent of a synthetic ester having a viscosity of 30 to 100 mm ² / s; 10-30% by weight of vegetable natural fats and oils; 10-30 weight% of fixative mineral oil; 1.7 to 5.5 weight percent emulsifier; 3-7 wt% of extreme pressure agent; 1 to 3 weight percent of a lubrication improver; And A water-soluble cold rolled oil composition comprising 0.3 to 2.0% by weight of at least one additive selected from the group consisting of antioxidants, corrosion inhibitors and microbial inhibitors. The method of claim 1, The synthetic ester is a C ₁₂ ~ C ₁₈ fatty acid hindered triester, characterized in that the water-soluble cold rolling oil composition. The method of claim 1, The vegetable natural fat or oil is water-soluble cold rolled oil composition, characterized in that at least one selected from the group consisting of palm oil and palm kernel oil. The method of claim 1, The fixing mineral oil is a water-soluble cold rolled oil composition, characterized in that the fine solvent-purified hydroparaffin distillate. The method of claim 1, The emulsifier is 1.0 to 3.0% by weight polyethylene glycol emulsifier, 0.5 to 1.5% by weight amine salt emulsifier and 0.2 to 1.0% by weight alcohol-based emulsifier water-soluble cold rolled oil composition. The method of claim 1, The extreme pressure agent is a water-soluble cold rolling oil composition, characterized in that consisting of a mixture of a phosphorous extreme pressure agent and a sulfur-based extreme pressure agent. The method of claim 1, The lubrication enhancer stearic acid, palm fatty acid, oleic acid, C ₃₀ C ₃₆ A water-soluble cold rolled oil composition, characterized in that it is selected from the group consisting of dimer acids and acrylated fatty acid esters. The method of claim 1, The antioxidant is a water-soluble cold rolled oil composition, characterized in that the phenol-based antioxidant. The method of claim 1, The microbial growth inhibitor is a water-soluble cold rolling oil composition, characterized in that the benzoic acid sodium derivative.

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