KR20130064363A - Coating composition for scale resistance, method for manufacturing steel sheet using the smae - Google Patents

Abstract

PURPOSE: A coating composition is provided to reduce amount of generated scale in a cold pressing process, and to use water as a solvent, thereby preventing fire and reducing environmental contamination. CONSTITUTION: A scale-resistant coating composition comprises 10-90 wt% of an aqueous resin, 1-60 wt% of copper or copper compound, and water as a solvent. A manufacturing method of a steel sheet comprises a step of preparing a steel slab(100); a step of coating the surface of the steel slab with the scale-resistance composition; a step of heating the steel-slab; and a step of manufacturing the steel sheet by rolling the heated steel slab. The amount of coating composition to be coated on the steel slab is 10-500 g/m^2.

Description

Resistant coating composition, steel sheet manufacturing method using the same {COATING COMPOSITION FOR SCALE RESISTANCE, METHOD FOR MANUFACTURING STEEL SHEET USING THE SMAE}

The present invention relates to a surface coating composition capable of reducing the amount of scale generated in the steel manufacturing process and a method for producing a steel sheet using the same.

According to the World Steel Association data, global crude steel production exceeded 1.4 billion tons in 2009, and according to the Korea Steel Association, domestic crude steel production exceeded 50 million tons in 2010.

Most of the steel produced is formed into steel slabs through steelmaking and performance in the production process, and the steel slabs are processed into hot rolled coils through a hot rolling process. At this time, the steel slab is subjected to a heat treatment of about 1000 ~ 1200 ℃ in order to undergo a hot rolling process, the steel slab exposed to high temperature is formed a scale called iron oxide on the surface. The main component of the scale is iron oxide, which is known as about 1% of the total crude steel production, which corresponds to a huge amount equivalent to 500,000 tons of domestic crude steel production in 2010.

The scale created in this way affects the quality of the steel, so in most cases the scale is removed.

Although the scale is removed during the steel production process, it is recovered and recycled in various fields, but since the scale is lower than that produced and sold as a steel product, reducing the scale generation may bring a lot of benefits.

In addition, when scale is generated, a process such as pickling by acid is required to remove it, so the risk of causing environmental pollution is very high, and a large cost is required to deal with it. This is necessary.

In comparison, various methods are known for techniques for removing such scales, but not for anti-scaling coatings intended to suppress scale generation.

One aspect of the present invention is to provide a scale-resistant coating composition that can reduce the amount of scale generated during the heat treatment process in the process of producing a steel sheet, a method for producing a steel sheet using the same.

The first aspect of the present invention provides a scale-resistant coating composition comprising 10 to 90% by weight of an aqueous resin, 1 to 60% by weight of aluminum, 1 to 60% by weight of copper or a copper compound, and water as a solvent.

In addition, the second aspect of the present invention comprises the steps of preparing a steel slab;

Coating the surface of the steel slab with an aqueous resin: 10 to 90% by weight, aluminum: 1 to 60% by weight, copper or copper compound: 1 to 60% by weight, and a solvent;

Heating the coated steel slab; And

It provides a method for producing a steel sheet comprising the step of manufacturing a steel sheet by rolling the heated steel slab.

According to the present invention, in addition to the rolling process of the slab, there is an advantage that can reduce the amount of scale generated in the process of the scale of the steel sheet, the coating composition of the present invention by using water as a solvent, the risk of fire It can reduce, and there is an advantage that can reduce the environmental pollution.

1 is a cross-sectional view showing a cross-section is coated on the steel slab resistance coating composition of the present invention.

Hereinafter, the present invention will be described in detail.

The present inventors coated the surface of the steel slab in order to solve the problem that the scale (iron oxide) is generated on the surface of the steel slab in the heating step before hot rolling, when hot-rolling the slab to manufacture a steel sheet The present invention was led while studying ways to suppress scale generation.

That is, the present inventors have studied in depth how to reduce the scale of steel slab generation, increase the stability by minimizing the risk of fire even under the condition of heating up to 1200 ° C, and to easily apply the coating to the steel slab. The result was the present invention.

First, the scale-resistant coating composition of the present invention will be described in detail.

The scale-resistant coating composition of the present invention preferably contains an aqueous resin: 10 to 90% by weight, aluminum: 1 to 60% by weight, copper or a copper compound: 1 to 60% by weight, and water as a solvent.

The coating composition uses water as a solvent instead of a solvent. The use of the water is to minimize the risk of fire even at the same time when used at a high temperature of more than 1200 ℃.

It is preferable that the coating composition of this invention contains 10-90 weight% of aqueous resins. The aqueous resins include polyurethanes, polyesters, epoxy resins, alkyd resins, phenol resins, melamine resins, acrylates and methacrylates;

Organic-inorganic compounds consisting of oligosiloxanes and polysiloxanes by hydrolysis and condensation of alkylalkoxysilanes, alkoxysilanes or mixtures thereof;

Silicones, silicone resins and organic modified silicone resins;

Silicates, polyphosphates and aluminosilicates and the like can be used.

The aqueous resin maintains an appropriate viscosity when applying the coating composition to a steel slab, and provides workability, and serves to harden at a relatively low temperature during heat treatment so that heat-resistant pigments and the like in the coating composition adhere to the steel slab surface.

The content of the aqueous resin is preferably 10 to 90% by weight. When the content of the resin is less than 10% by weight, sufficient fluidity is not provided, so that it is difficult to properly coat the steel slab surface, and there is a possibility that heat-resistant pigments easily fall off the surface due to weak surface adhesion after curing of the resin. On the other hand, when the content is more than 90% by weight, the content of the heat-resistant pigment in the coating composition is relatively small, it is difficult to secure sufficient heat resistance.

The coating composition preferably contains 1 to 60% by weight of aluminum and 1 to 60% by weight of copper or a copper compound.

The aluminum and copper or copper compounds are heat-resistant pigments, each having a melting point of 660 ° C. and 1084 ° C. and having a melting point at a temperature of 600 ° C. or higher, which is the temperature at which steel slabs are scaled during heat treatment. It causes changes and absorbs the surrounding heat and oxidative factors to prevent the steel slab surface from oxidizing and producing scale.

It is preferable that the said aluminum and copper or a copper compound are aqueous particles. In the case of oily particles other than aqueous particles, solution coagulation occurs at high temperature heat treatment, and solution stability cannot be secured.

The content of the aluminum and copper or copper compound is preferably 1 to 60% by weight, respectively. When the content of the heat-resistant pigment aluminum and copper or copper compound in the coating composition is less than 1% by weight, it is difficult to secure heat resistance, and when it exceeds 60% by weight, sufficient fluidity is not provided, so that it is difficult to properly coat the steel slab surface. The surface adhesion after the curing of the resin is weak, there is a possibility that heat-resistant pigments easily fall off the surface.

The aluminum and copper or copper compound is preferably surface-treated with silane, phosphate, silica, benzotriazole and the like. The surface treatment serves to increase the resistance to heat by preventing the aluminum and copper or copper compounds are oxidized in the aqueous solution.

On the other hand, it is more preferable that the addition ratio of the said aluminum and copper or a copper compound is the ratio of 10: 1-1:10. When the addition ratio of aluminum and copper or copper compound is less than 10: 1, the amount of addition of copper or copper compound is insufficient and the amount of high temperature scale generated at a temperature of 1000 ° C. or more is increased. When the addition ratio of aluminum and copper or a copper compound exceeds 1:10, the amount of aluminum added is insufficient and the amount of low temperature scale generated at a temperature between 600 and 1000 ° C is increased. More preferably, the aluminum: copper or copper compound is 1: 1.

The particle size of the aluminum and copper or copper compound is preferably 1 mm or less based on the average particle size (D50). When the average particle size of the aluminum and copper or copper compound exceeds 1 mm, it is difficult to uniformly disperse in the coating layer due to the excessively large particle size, thereby making it difficult to secure scale resistance and heat resistance. More preferably, the average particle size of the aluminum and the copper or copper compound is 100 μm or less.

The particle size is preferably 1 nm or more. In order to make the particle size of the aluminum and copper or copper compound smaller than 1 nm, an additional process for reducing the particle size is required, and the cost thereof is excessively increased.

The coating composition of the present invention may further comprise a curing agent. The curing agent causes the curing of the aqueous resin in the range of 60 to 300 ℃ during high temperature heating and serves to increase the viscosity. Since the viscosity of the resin is lowered during the high temperature heating, there is an advantage of preventing problems such as flowing down from the surface of the slab. The content of the curing agent is preferably at least 5% by weight relative to the aqueous resin. When the amount of the curing agent added is less than 5% by weight of the aqueous resin, since the effect of increasing the viscosity is small and the coating composition may flow during the heat treatment, the content of the curing agent is preferably 5% by weight or more with respect to the aqueous resin.

Hereinafter, the manufacturing method of the scale-resistant coating composition of the present invention will be described in detail.

First, a raw material having the composition is prepared, and the prepared raw material is mixed with water as a solvent and stirred to prepare a scale-resistant coating composition of the present invention.

The said stirring method is not specifically limited, It is performed by the conventional method performed in the technical field to which this invention belongs.

Hereinafter, the manufacturing method of the steel plate using the scale-resistant coating composition of the present invention will be described in detail.

In the steel sheet manufacturing method of the present invention, after preparing the steel slab, the surface of the steel slab, aqueous resin: 10 to 90% by weight, aluminum: 1 to 60% by weight, copper or copper compound: 1 to 60% by weight and a solvent Coating a scale resistant coating composition comprising water.

The coating is preferably coated with a coating composition of more than 10g / ㎡ on the steel slab surface. If the coating composition is less than 10g / ㎡ the amount of heat-resistant pigments are insufficient to reduce the scale resistance. The coating is preferably at most 500 g / m 2. If the coating composition exceeds 500g / ㎡ due to the excessive coating, there is a problem to flow down on the surface of the slab, there is a problem that can occur excessively cost.

In the present invention, it is preferable to further include the step of removing the coated coating coating composition before heating the steel slab before rolling.

Thereafter, the coated steel slab is heated, and the heated steel slab is rolled to prepare a steel sheet.

The heating is to be heated to the required temperature according to the type of steel sheet desired, the rolling also depends on the target steel sheet.

On the other hand, after the rolling may be cooled as needed, or may further comprise an additional cold rolling process.

The present invention provides a steel sheet manufactured by the above manufacturing method. Since the steel sheet has a scale-resistant coating layer formed on the surface of the steel slab during the reheating process at a high temperature, the amount of scale generated in the manufactured steel sheet is reduced, thereby improving the product quality due to excellent surface characteristics and scale generation.

Hereinafter, embodiments of the present invention will be described in detail. The following examples are only for the understanding of the present invention, but not for limiting the present invention.

(Example)

First, a steel slab specimen for heat treatment was prepared. The steel slab specimens have a size of 10 cm, 10 cm, and 1.5 cm in width, length, and thickness, respectively. Hereinafter, the Inventive Example and Comparative Example compositions were prepared by the following method, and the following coating composition 200 was coated on the surface of the steel slab 100 as shown in FIG. 1.

Preparation of Inventive Example 1

40% by weight of an aqueous phenoxy resin (Inchem inc., PKHW-35), 2% by weight of a curing agent (Cytec industry, Cymel 303) (5% by weight of the resin), aqueous aluminum particles (Silberline, Aquasil BP 205) 15 The coating composition prepared by adding the weight percent, 35% by weight of aqueous brass particles (ECKART, ROTO safe aque 200 821 rich gold), 8% by weight of distilled water in a beaker and stirred at 2000 RPM for about 1 hour at room temperature of the steel slab specimen About 385 g / m 2 was coated on the surface.

Preparation of Inventive Example 2

40% by weight of aqueous urethane resin (Cam Nine Corporation, PO 200), 2% by weight of curing agent (Cytec industry, Cymel 303) (5% by weight of the resin), 15% by weight of aqueous aluminum particles (Silberline, Aquasil BP 205), A coating composition prepared by adding 35% by weight of aqueous brass particles (ECKART, ROTO safe aque 200 821 rich gold) and 8% by weight of distilled water to a beaker and stirring at 2000 RPM for about 1 hour at room temperature was prepared as described above. About 10 g / m 2 was coated on the surface of the specimen.

Preparation of Inventive Example 3

40% by weight of aqueous urethane resin (Cam Nine Corporation, PO 200), 2% by weight of curing agent (Cytec industry, Cymel 303) (5% by weight of the resin), 15% by weight of aqueous aluminum particles (Silberline, Aquasil BP 205), 15% by weight of aqueous brass particles (ECKART, ROTO safe aque 200 821 rich gold), 10% by weight of fly ash (Kehana cement) and 18% by weight of distilled water were prepared by stirring at 2000 RPM for 1 hour at room temperature. The coating composition was coated with about 10 g / ㎡ on the surface of the slab specimens as in Example 1.

Preparation of the conventional example

Steel slab specimens were prepared without using the anti-scale coating composition.

Preparation of Comparative Example 1

60% by weight of an aqueous epoxy resin (Kukdo Chemical, KEM-128-70), 5% by weight of a curing agent (Cytec industry, Cymel 303) (8.3% by weight of the resin), 0.1% by weight of aqueous aluminum particles (Showa, CS460SW) , 10% by weight of aqueous brass particles (ECKART, ROTO safe aque 200 821 rich gold), 24.9% by weight of distilled water in a beaker, the coating composition prepared by stirring at 2000 RPM for about 1 hour at room temperature as described above Example 1 About 10 g / m 2 was coated on the surface of the slab specimens.

Preparation of Comparative Example 2

60% by weight of aqueous phenoxy resin (Inchem inc., PKHW-35), 5% by weight of curing agent (Cytec industry, Cymel 303) (8.3% by weight of the resin), 15% by weight of aqueous aluminum particles (Showa, CS460SW) , 0.5% by weight of aqueous brass particles (ECKART, ROTO safe aque 200 821 rich gold), 19.5% by weight of distilled water in a beaker and the coating composition prepared by stirring at 2000 RPM for about 1 hour at room temperature as described above Example 1 About 10 g / m 2 was coated on the surface of the slab specimens.

Preparation of Comparative Example 3

40% by weight of aqueous phenoxy resin (Inchem inc., PKHW-35), 3% by weight of a curing agent (Cytec industry, Cymel 303) (7.5% by weight of the resin), 20% by weight of aqueous aluminum particles (Showa, CS460SW) , 20% by weight of fly ash (Kyhana cement), 17% by weight of distilled water in a beaker and stirred at 2000 RPM for about 1 hour at room temperature, the coating composition was prepared in about 10g on the surface of the slab specimens as in Example 1 / M 2 was coated.

Preparation of Comparative Example 4

40% by weight of aqueous phenoxy resin (Inchem inc., PKHW-35), 3% by weight of hardener (Cytec industry, Cymel 303) (7.5% by weight of the resin), non-aqueous aluminum particles (ECKART, METALLUX 2153) 20 A coating composition prepared by adding 20% by weight of fly ash (Kayhana cement) and 17% by weight of distilled water to a beaker at 2000 RPM for about 1 hour at room temperature was prepared on the surface of the slab specimen as in Example 1 above. About 10 g / m 2 was coated.

Evaluation of scale resistance and solution stability

In order to confirm the scale resistance of the present invention, the scales generated by removing the scale generated by heat treatment of the invention examples, conventional examples and comparative examples at 1200 ° C. for 2 hours and subtracting the weight of the steel slab after heat treatment from the weight before heat treatment After the measurement, the amount of scale generated per unit area was determined by dividing the surface area of the slab, and the results are shown in Table 1.

On the other hand, in order to evaluate the solution stability of the coating composition of the present invention, after leaving the coating composition of the invention examples and comparative examples for 120 hours at 50 ℃ to measure the sludge generation and viscosity changes, the results are shown in Table 2 Shown in In the results of Table 2, ○ represents no sludge, less than 20% of the viscosity change, △ is not generated sludge, more than 20% of the viscosity change, × represents the result of sludge generation.

division Scale generation amount (g / ㎡) Inventory 1 3852 Inventory 2 3914 Inventory 3 3947 Conventional example 4014 Comparative Example 1 4469 Comparative Example 2 4787 Comparative Example 3 5167 Comparative Example 4 -

As can be seen from the results of Table 1, all the steel slabs coated and heat-treated after coating using the coating composition satisfying the scope of the present invention were confirmed to have reduced scale generation amount compared to the conventional example.

However, Comparative Examples 1 and 2 did not fall within the scope of the present invention, the aluminum and copper content, it was confirmed that the scale occurs more than when using the coating composition, Comparative Example 3 is a fly ash (aluminum and inorganic pigments) When the fly ash) was added, it was confirmed that the scale generation amount further increased. Comparative Example 4 was solidified in the solution manufacturing process using aluminum particles that are not aqueous, coating was not possible.

division Solution stability evaluation Inventory 1 ○ Inventory 2 ○ Inventory 3 ○ Conventional example - Comparative Example 1 ○ Comparative Example 2 ○ Comparative Example 3 ○ Comparative Example 4 ×

As in the present invention, both the aqueous resin and the aqueous heat-resistant pigments were excellent in solution stability, but in the case of Comparative Example 4 due to the use of non-aqueous oily aluminum particles, solution solidification occurs, so that solution stability is not secured. Did.

100 ..... Gang Slavic
200 ..... scale coating composition

Claims (9)

Water-based resin: 10 to 90% by weight, aluminum: 1 to 60% by weight, copper or copper compound: 1 to 60% by weight and a solvent-resistant coating composition comprising water.
The method according to claim 1,
The aqueous resin is
First group consisting of polyurethane, polyester, epoxy resin, alkyd resin, phenol resin, melamine resin, acrylate and methacrylate
Second group of organic-inorganic compounds consisting of oligosiloxanes and polysiloxanes by hydrolysis and condensation of alkylalkoxysilanes, alkoxysilanes or mixtures thereof
Third group consisting of silicone, silicone resin and organic modified silicone resin
In a fourth group of pure inorganic compounds consisting of silicates, polyphosphates and aluminosilicates,
Scale coating composition is at least one aqueous resin selected from the first to fourth groups.
The method according to claim 1,
Wherein the aluminum and copper or copper compound surface-treated with any one selected from the group consisting of silane, phosphate, silica and benzotriazole.
The method according to claim 1,
The aluminum and copper or copper compound is a scale coating composition comprising 10: 1 ~ 1:10 ratio.
The method according to claim 1,
The aluminum and copper or copper compound is an aqueous particle resistant coating composition.
The method according to claim 1,
The average particle size of the aluminum and copper or copper compound is 1nm ~ 1mm scale coating composition.
Preparing a steel slab;
Coating the surface of the steel slab with an aqueous resin: 10 to 90% by weight, aluminum: 1 to 60% by weight, copper or copper compound: 1 to 60% by weight, and a solvent;
Heating the coated steel slab; And
Manufacturing a steel sheet by rolling the heated steel slab
Method for producing a steel sheet comprising a.
The method of claim 7,
The coating composition is a method for producing a steel sheet coated on the steel slab surface in an amount of 10 ~ 500g / ㎡.
The method of claim 7,
After heating the steel slab, the method of manufacturing a steel sheet further comprising the step of removing the coated anti-scale coating composition before the rolling.

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