KR102223271B1 - A degreasing agent for a directional electric steel sheet and a degreasing method using the same - Google Patents

Abstract

The present specification relates to a degreasing agent for a grain-oriented electrical steel sheet and a degreasing method using the same, and in detail, a degreasing agent capable of removing rolling lubricant existing on the surface of a cold-rolled steel sheet prior to decarburization annealing and immersion annealing, and a degreasing method using the same. .
According to an embodiment of the disclosed degreasing method, it includes the step of immersing a cold-rolled steel sheet in a degreasing agent, wherein the degreasing agent is at least in wt%, glycerin: 1 to 5%, hydrogen peroxide: 7 to 13%, hydrofluoric acid: less than 4% It contains at least one type, and the balance contains alcohol having 1 to 8 carbon atoms and inevitable impurities.

Description

A degreasing agent for a directional electric steel sheet and a degreasing method using the same}

The present invention relates to a degreasing agent for a grain-oriented electrical steel sheet and a degreasing method using the same, and more particularly, to a degreasing agent capable of removing rolling lubricant existing on the surface of a cold-rolled steel sheet prior to decarburization annealing and immersion annealing, and a degreasing method using the same. .

The grain-oriented electrical steel sheet exhibits a Goss texture of {110}<001> in the rolling direction, and is a soft magnetic material with excellent magnetic properties in one direction or in the rolling direction.

In order to secure excellent soft magnetic properties, precise and accurate control of decarburization annealing and immersion annealing after cold rolling is important, and for this, the surface treatment state of the cold rolled steel sheet must be maintained at a good level. However, in order to cold-roll the grain-oriented electrical steel sheet, rolling lubricant is inevitably used, and the rolling lubricant remains on the surface of the cold-rolled steel sheet, so that the surface treatment state cannot be maintained at a good level.

Korean Registered Patent Publication No. 10-1625982 (announcement date: May 31, 2016)

In order to solve the above-described problem, the present invention is to provide a degreasing agent capable of degreasing the rolling lubricant remaining on the surface of a cold-rolled steel sheet, and a degreasing method using the same.

The degreasing agent for a grain-oriented electrical steel sheet according to an embodiment of the present invention contains at least one of less than 4% by weight, glycerin: 1 to 5%, hydrogen peroxide: 7 to 13%, and the remainder of carbon number 1 to 8 Contains alcohol and unavoidable impurities.

A method of degreasing a grain-oriented electrical steel sheet according to another embodiment of the present invention includes the step of immersing a cold-rolled steel sheet in a degreasing agent, wherein the degreasing agent is in weight %, glycerin: 1 to 5%, hydrogen peroxide: 7 to 13%, hydrofluoric acid: It contains at least one or more of less than 4%, and the balance contains alcohols having 1 to 8 carbon atoms and unavoidable impurities.

In addition, the step of immersing the cold-rolled steel sheet in the degreasing agent may include maintaining the temperature range of the degreasing agent at 20 to 30°C.

In addition, the step of immersing the cold-rolled steel sheet in the degreasing agent may include immersing the cold-rolled steel sheet in the degreasing agent for 3 to 5 minutes.

In addition, the step of drying the immersed cold-rolled steel sheet after washing with alcohol may be further included.

According to an example of the present invention, since the rolling lubricant remaining on the surface of the cold-rolled steel sheet is removed by a chemical method rather than a mechanical method, the reliability of the good surface treatment state can be increased.

According to an example of the present invention, by providing a degreasing agent for a grain-oriented electrical steel sheet and a degreasing method using the same, the target oxide layer amount (800±50ppm) and the sediment mass (180±50 ppm) by smoothing the reaction between moisture and ammonia during decarburization and immersion annealing. 10ppm) can be secured.

Hereinafter, preferred embodiments of the present invention will be described. However, the embodiments of the present invention may be modified into various other forms, and the technical idea of the present invention is not limited to the embodiments described below. In addition, embodiments of the present invention are provided in order to more completely explain the present invention to those with average knowledge in the art.

The terms used in the present application are only used to describe specific examples. So, for example, a singular expression includes a plural expression unless the context clearly has to be singular. In addition, terms such as "include" or "include" used in the present application are used to clearly refer to the existence of features, steps, functions, components or combinations thereof described in the specification, but other features It should be noted that it is not used to preliminarily exclude the presence of elements, steps, functions, components, or combinations thereof.

Meanwhile, unless otherwise defined, all terms used in the present specification should be viewed as having the same meaning as commonly understood by a person of ordinary skill in the art to which the present invention belongs. Therefore, unless clearly defined in the specification, a specific term should not be interpreted as an excessively ideal or formal meaning. For example, in the present specification, expressions in the singular include plural expressions unless the context clearly has exceptions.

In addition, "about", "substantially" and the like in the present specification are used in or close to the numerical value when manufacturing and material tolerances specific to the stated meaning are presented, and are accurate to aid understanding of the present invention. Or absolute figures are used to prevent unreasonable use of the stated disclosure by unconscionable infringers.

In addition, "cold-rolled steel sheet" in the present specification is used as a meaning to refer to a grain-oriented electrical steel sheet after cold rolling and before decarburization and immersion annealing.

In order to secure excellent soft magnetic properties, precise and accurate control of decarburization annealing and immersion annealing after cold rolling is important, and for this, the surface treatment state of the cold rolled steel sheet must be maintained at a good level. However, in order to cold-roll the grain-oriented electrical steel sheet, rolling lubricant is inevitably used, and the rolling lubricant remains on the surface of the cold-rolled steel sheet, so that the surface treatment state cannot be maintained at a good level.

In order to solve the above-described problem, the present invention is to provide a degreasing agent capable of degreasing the rolling lubricant remaining on the surface of a cold-rolled steel sheet, and a degreasing method using the same.

The degreasing agent of the grain-oriented electrical steel sheet according to an embodiment of the present invention contains at least one or more of in wt%, glycerin: 1 to 5%, hydrogen peroxide: 7 to 13%, hydrofluoric acid: less than 4%, and the balance carbon number is 1 to 8 Contains alcohol and unavoidable impurities.

Hereinafter, the reason for limiting the composition will be described in detail. All of the following component compositions refer to% by weight unless otherwise specified.

Glycerin: 1 to 5% by weight

Glycerin is a component that increases the degree of activation to decompose rolling lubricant remaining on the surface of the cold-rolled steel sheet by lowering the surface tension between the rolling lubricant and the atmosphere and the steel sheet by acting as a surfactant. In the present invention, it is preferable that the content of glycerin is 1% by weight or more in order to exhibit this effect.

On the other hand, when the content exceeds 5% by weight, the decomposition activity of the rolling powder oil is excessively increased, so that a difference in the degreasing rate occurs locally, it is difficult to uniformly degrease the surface, and the surface roughness may increase. Therefore, in the present invention, the content of glycerin is preferably controlled to 1 to 5% by weight.

Hydrogen peroxide: 7 to 13% by weight

Hydrogen peroxide is a component for decomposing rolling lubricant remaining on the surface of the cold rolled steel sheet. In the present invention, it is actively added to exhibit this effect.

In the present invention, when the hydrogen peroxide content is less than 7% by weight, the degreasing rate of the rolling lubricant is significantly lowered, and rust may occur on the surface of the steel sheet during degreasing. On the other hand, when the content exceeds 13% by weight, the degreasing speed is excessively accelerated, resulting in a difference in the degreasing speed locally, making it difficult to uniformly degrease the surface, thereby increasing the surface roughness. Therefore, in the present invention, the content of hydrogen peroxide is preferably controlled to 7 to 13% by weight.

Hydrofluoric acid: less than 4% by weight

Hydrofluoric acid decomposes the rolling lubricant remaining on the surface of the cold-rolled steel sheet, but it is a very harmful compound to the human body, so it is preferable not to use it. However, it is added when the degreasing rate of a degreasing agent obtained by mixing at least one component of glycerin and hydrogen peroxide alone or in the above-described composition is slow or unstable.

In the present invention, when the hydrofluoric acid is 4% by weight or more, the result of the degreasing treatment is the same as that of the case where the hydrofluoric acid is less than 4% by weight, so it is preferable to control the content of hydrofluoric acid to less than 4% by weight.

The remaining component of the present invention is alcohol. However, since unintended impurities from raw materials or the surrounding environment may inevitably be mixed in a typical manufacturing process, this cannot be excluded. Since the impurities are known to anyone of ordinary skill in the manufacturing process, all the contents are not specifically mentioned in the present specification.

In the present invention, the alcohol may be an alcohol having 1 to 8 carbon atoms, and any of ordinary methanol and ethanol may be used.

According to an example of the present invention, the degreasing agent for a grain-oriented electrical steel sheet having the above composition is sufficient as long as it can remove the rolling lubricant remaining on the surface of the cold-rolled steel sheet, and can be prepared by various methods as long as there is no adverse effect in terms of chemical reaction.

According to an example of the present invention, when one selected from the group consisting of glycerin, hydrogen peroxide, and hydrofluoric acid is used alone, it is added to alcohol by adjusting to the above composition content range, or when two or more types are mixed, glycerin is added to alcohol. After the addition, hydrofluoric acid is added to alcohol, and then hydrogen peroxide is added to the alcohol to prepare the degreasing agent of the present invention.

Hereinafter, a method for degreasing a grain-oriented electrical steel sheet using the degreasing agent of the present invention will be described in detail.

In the present invention, the grain-oriented electrical steel sheet can be manufactured in various ways from known techniques by a person skilled in the art. According to an example, the grain-oriented electrical steel sheet includes heating a slab, hot rolling the slab, annealing a hot-rolled steel sheet, cold rolling a heat-treated steel sheet, decarburization and immersion annealing the cold-rolled steel sheet, and the final It can be prepared including the step of annealing.

The method for degreasing the grain-oriented electric field plate of the present invention is to effectively remove rolling lubricant remaining on the surface of the cold-rolled steel sheet before decarburization and immersion annealing on the cold-rolled steel sheet that has been subjected to the cold-rolling step.

A method of degreasing a grain-oriented electrical steel sheet according to an embodiment of the present invention may include immersing the cold-rolled steel sheet in a degreasing agent. The degreasing agent may contain at least one or more of 1 to 5% by weight, glycerin: 1 to 5%, hydrogen peroxide: 7 to 13%, hydrofluoric acid: less than 4%, and the balance may include an alcohol having 1 to 8 carbon atoms and unavoidable impurities. , The reason for limiting the component range has been described above and thus will be omitted.

In the degreasing method according to one embodiment of the present invention, the temperature range of the degreasing agent is preferably maintained at 20 ~ 30 ℃. When the temperature of the degreasing agent is less than 20°C, the degreasing treatment may not be performed properly because a chemical reaction to remove the degreasing agent and the oil present on the surface of the cold-rolled steel sheet does not sufficiently occur. On the other hand, when the temperature of the degreasing agent exceeds 30°C, the reaction rate of degreasing treatment is excessively accelerated, resulting in a difference in the degreasing rate locally, making it difficult to uniformly degrease the surface, thereby increasing the surface roughness.

The degreasing method according to an embodiment of the present invention may include immersing the cold-rolled steel sheet in a degreasing agent for 3 to 5 minutes. If it is immersed for less than 3 minutes, the degreasing treatment may not be properly performed due to insufficient time for the degreasing reaction, and if it is immersed for more than 5 minutes, the degreasing treatment proceeds excessively and the surface roughness may be rather high.

The degreasing method according to an exemplary embodiment of the present invention may further include a step of immersing the cold-rolled steel sheet in a degreasing agent to perform degreasing, and then washing the cold-rolled steel sheet in alcohol and drying it.

In addition, after washing with alcohol and drying, residual degreasing agent may be removed, and dried at high temperature through natural drying at room temperature or hot air of 40 to 100°C.

According to an example of the present invention, since the rolling lubricant remaining on the surface of the cold-rolled steel sheet is removed by a chemical method using a degreasing agent as described above, not a mechanical method, reliability of the good surface treatment state can be increased.

According to an example of the present invention, by providing a degreasing agent for a grain-oriented electrical steel sheet and a degreasing method using the same, it is possible to improve the surface treatment state by removing the rolling lubricant existing on the surface of the cold-rolled steel sheet. By smoothly reacting with ammonia, the target amount of oxide layer (800±50ppm) and saliva mass (180±10ppm) can be secured.

Hereinafter, the present invention will be described in more detail through examples. However, it should be noted that the following examples are for illustrative purposes only and are not intended to limit the scope of the present invention. This is because the scope of the present invention is determined by matters described in the claims and matters reasonably inferred therefrom.

{Example}

After preparing each degreasing agent composed of the ingredients in Table 1 below and the rest of the alcohol, the temperature of the degreasing agent was maintained at 25°C, the cold-rolled steel sheet was immersed for 4 minutes, and then washed by immersing in alcohol for 4 minutes or more, and then on a specimen naturally dried at room temperature. For the decarburization annealing heat treatment, the amount of the oxide layer obtained and the mass of the immersion were shown together in Table 1. The amount of the oxide layer and the mass of the needle are measured by the dry method, and the target values are 800±50ppm and 180±10ppm.

division Composition of degreasing agent Amount of oxide layer
(ppm) Saliva mass
(ppm) glycerin
(weight%) Hydrogen peroxide
(weight%) Foshan
(weight%) Comparative Example 1 0.5 5.2 0 620 130 Invention Example 1 2.8 10.4 2.8 810 180 Comparative Example 2 7.3 15.2 5.4 980 160 Invention Example 2 4.7 11.6 3.5 830 180

Referring to Table 1, it can be seen that the degreasing agent of Inventive Examples 1 and 2 has the result that the amount of oxidized layer and the immersion mass meet the target values. Soft magnetic properties can be secured.

On the other hand, in Comparative Example 1, since the content of glycerin and hydrogen peroxide was less than that of the inventive example, the degreasing treatment was not properly performed. For this reason, the amount of the oxide layer and the needle mass in Comparative Example 1 were smaller than the amount of the oxide layer and the needle mass targeted by the present invention. In Comparative Example 1, since the amount of oxide layer was less than the target value, the formation of an appropriate base coating on the steel sheet was inhibited, causing surface defects, and the needle mass was less than the target value, resulting in normal recrystallization of other textures other than the Goss aggregate. There is a problem that causes poor magnetism.

In addition, in Comparative Example 2, the content of glycerin, hydrogen peroxide, and hydrofluoric acid was excessive compared to the Invention Example, so that the degreasing treatment was excessively performed, and the surface roughness was increased. For this reason, the amount of the oxide layer and the amount of immersion in Comparative Example 2 were larger than the amount of oxidized layer and the immersion mass targeted by the present invention. In Comparative Example 2, since the amount of the oxide layer was greater than the target value, the steel sheet was peroxidized and the color of the base coating was unevenly formed, causing surface defects, and the sediment mass was greater than the target value, so that the secondary recrystallization behavior of the grain-oriented electrical steel sheet did not occur properly. There is a problem in that the degree of integration decreases, in other words, secondary recrystallization of Goth crystal grains of poor quality occurs, resulting in poor magnetism.

As described above, although exemplary embodiments of the present invention have been described, the present invention is not limited thereto, and those of ordinary skill in the art are within the scope of not departing from the concept and scope of the following claims. It will be appreciated that various modifications and variations are possible.

Claims (5)

In the degreasing method of a grain-oriented electrical steel sheet manufactured by decarburization annealing and immersion annealing,
In wt%, glycerin: 1 to 5%, hydrogen peroxide: 7 to 13%, hydrofluoric acid: less than 4%, and the remainder of the cold-rolled steel sheet in a degreasing agent of 20 to 30 ℃ containing an alcohol having 1 to 8 carbon atoms and inevitable impurities Including; immersing for 3 to 5 minutes;
A method of degreasing a grain-oriented electrical steel sheet, characterized in that the amount of the oxide layer measured by the dry analysis method after decarburization annealing and immersion annealing is 750 to 850 ppm, and the sediment mass is 170 to 190 ppm. The method of claim 1,
Washing the immersed cold-rolled steel sheet in alcohol and then drying the method of degreasing the grain-oriented electrical steel sheet further comprising.



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