KR101195897B1 - Gloss-controllable uv curing paint composition and steel sheet coated by the same - Google Patents

Abstract

PURPOSE: A UV-curable paint composition is provided to embody various glosses from a single pain composition while maintaining coating physical properties like coating adhesion, etc. CONSTITUTION: A UV-curable paint composition comprises an oligomer, a photopolymerizable monomer, a photoinitiator, and a quencher, and satisfies formula 1: 0.1 <= D/T <= 3 and formula 2: 2: 0.3 <= C/T <= 3. In chemical formula 1 and 2, D is an average particle size(micron), T is a thickness(micron) of a coating formed of the UV curable paint composition by through UV curing, and C is a content(parts by weight) of a quencher comprised in the UV curable paint composition. [Reference numerals] (AA) Quencher; (BB) Exposed part; (CC) UV-curable type paint composition(cured); (DD) UV-curable type paint composition(non-cured); (EE) Steel plate

Description

Gloss-controllable UV curing paint composition and steel sheet coated by the same}

The present invention relates to a UV curable coating composition and a steel sheet coated thereby.

In general, UV-curable paints, unlike conventional thermosetting resin paints, do not contain solvents and can be rapidly cured using ultraviolet rays, and basically contain oligomers, monomers, and photoinitiators having a lower molecular weight than thermosetting resin paints. . The thermosetting resin paint containing a solvent has a problem that the intermolecular bonding density, that is, the degree of crosslinking is low, so that the hardness of the coating film is low, and it is easily damaged by external friction. On the other hand, since UV-curable paints that do not use solvents have a high crosslinking degree, the hardness of the coating film is high, the scratch resistance and the stiffness are excellent, and the gloss is very high.

However, with the recent advancement of products in the field of home appliances and building materials, not only the basic requirements such as corrosion resistance, processability and chemical resistance of coated steel sheets, but also aesthetic characteristics such as gloss and sensibility and durability after transportation and installation Scratch resistance and the like are required at the same time to ensure. UV curable paint is a coating paint that meets these demands, but it is difficult to design the paint to meet various conditions for appearance. For example, home appliances such as washing machines, refrigerators, and TVs require high glossiness and sensibility, while indoor panels and architectural exterior materials require very low gloss and excellent scratch resistance.

Conventionally, a glossing agent such as silica, alumina or synthetic polymer powder is added to a UV curable paint composed of an oligomer, a monomer and a photoinitiator, and various dispersants are added to a predetermined amount to uniformly disperse the matting agent, thereby controlling the gloss of the UV curable paint. Have been. However, since the glossiness required for the product is different according to the consumer, the content of the matting agent and the dispersant must be adjusted every time in order to control the glossiness, thereby increasing the test cost, as well as corrosion resistance, film adhesion and processability. It affects the basic physical properties of the same coating film has caused a problem that the variation of the physical properties for each product.

Therefore, while a variety of gloss can be realized from a single UV-curable paint, the development of a UV-curable paint is urgently needed to maintain the basic physical properties of the coating film except for the glossiness.

An object of the present invention is to provide a UV curable coating composition capable of controlling gloss, thereby providing a coated steel sheet and a method for producing the steel sheet.

The present invention is a means for solving the above problems, oligomers; Photopolymerizable monomers; Photoinitiators; And it provides the UV curable coating composition containing the quencher, and satisfies the conditions of the general formulas (1) and (2).

[Formula 1]

0.1 ≤ D / T ≤ 3

[Formula 2]

0.3 ≤ C / T ≤ 3

In Formulas 1 and 2, D represents the average particle size (unit: μm) of the quencher, T represents the thickness (unit: μm) of the coating film formed by UV curing the UV curable coating composition, C is The content (unit: parts by weight) of the matting agent included in the UV curable coating composition is shown, and the parts by weight represent a weight ratio.

The present invention is another means for solving the above problems, a steel sheet; Provided is a steel sheet which is formed on one or both surfaces of the raw material steel sheet and includes a coating layer containing a cured product of the UV curable coating composition according to the present invention.

The present invention as another means for solving the above problems, the step of coating the UV-curable coating composition according to the present invention on one or both sides of the raw material steel sheet, and adjusting the surface gloss by irradiating near infrared; And curing the UV curable coating composition through UV irradiation to form a coating layer.

UV-curable coating composition of the present invention can implement a variety of gloss from a single coating composition, while maintaining the basic physical properties required when forming a coating film. In addition, the steel sheet coated with the UV-curable coating composition of the present invention by adjusting the irradiation amount of near-infrared in the process of forming the coating layer by coating the UV-curable coating composition on the steel sheet, it is possible to adjust the gloss, according to the needs of the consumer It is easy to adjust the gloss of the product according to, can bring a cost savings.

1 to 4 are cross-sectional views of steel sheets according to one embodiment of the present invention.
5 and 6 are cross-sectional views according to one embodiment of the coating layer included in the steel sheet of the present invention.
7 is a view schematically showing a method for manufacturing a steel sheet according to one embodiment of the present invention.

The present invention is an oligomer; Photopolymerizable monomers; Photoinitiators; And it relates to a UV curable coating composition comprising a matting agent, satisfying the conditions of the general formulas (1) and (2).

[Formula 1]

0.1 ≤ D / T ≤ 3

[Formula 2]

0.3 ≤ C / T ≤ 3

In Formulas 1 and 2, D represents the average particle size (unit: μm) of the quencher, T represents the thickness (unit: μm) of the coating film formed by UV curing the UV curable coating composition, C is The content (unit: parts by weight) of the matting agent included in the UV curable coating composition is shown, and the parts by weight represent a weight ratio.

Hereinafter, the UV curable coating composition of the present invention will be described in detail.

The UV curable coating composition of the present invention contains an oligomer, a photopolymerizable monomer, a photoinitiator and a quencher, and satisfies the conditions of the general formula (1). That is, the UV curable coating composition of the present invention, in consideration of the thickness (T) of the coating film prepared using the coating composition, so that the D / T value is 0.1 to 3, preferably 0.5 to 1.5, the matting agent The average particle size (D) of can be adjusted.

Specifically, for example, when the coating film having a thickness of 1 μm to 20 μm is formed on the steel sheet using the UV curable coating composition of the present invention, the present invention is within the range satisfying the D / T value. The average particle size of the matting agent included in the UV curable coating composition may be 0.1 ㎛ to 60 ㎛.

The method for measuring the average particle size of the matting agent in the present invention is not particularly limited, and means commonly used in this field can be employed without limitation, and can be measured using, for example, a particle size analyzer. Can be.

The matting agent included in the UV-curable coating composition of the present invention is a process of coating the UV-curable coating composition on a material steel sheet and curing to form a coating layer, wherein the matting agent particles and the coating layer are exposed on the surface of the coating layer. It may be divided into quencher particles located therein. Among the matting agent particles, the particles having a great influence on the glossiness after completion of curing of the coating composition of the present invention are the matting agent particles exposed to the surface of the coating layer.

Therefore, in the present invention, the D / T value, which is a relation between the average particle size (D) of the matting agent and the thickness (T) of the coating layer, may be 0.1 to 3, preferably 0.5 to 1.5. When the D / T value is less than 0.1, a large number of quencher particles may be located inside the coating layer to reduce the ratio of the quencher particles exposed to the surface of the coating layer, and the coating composition may have the same amount of quencher. Even if it contains, the finer the particles of the matting agent is very high, the viscosity of the coating composition is very high, and therefore a large amount of dispersant should be used to prevent the aggregation of particles that may occur during coating of the coating composition, which is the basic physical properties of the coating film It may be a factor to lower the coating adhesion or corrosion resistance. In addition, when the D / T value exceeds 3, most of the matting agent is exposed to the surface of the coating layer, so that only a low gloss coating is always obtained, so that various gloss adjustments may be difficult, and the coated steel sheet During the molding process, the matting agent particles exposed on the surface of the coating layer may drop off, which may contaminate the press die or cause scratches on the surface of the coating layer.

Therefore, the UV curable coating composition of the present invention may include a matting agent having an average particle size that may satisfy the condition of the general formula 1 in consideration of the thickness of the coating layer to be prepared using the same.

The UV curable coating composition of the present invention further satisfies the condition of the general formula (2).

In the UV curable coating composition of the present invention, in consideration of the thickness (T) of the coating film prepared using the coating composition, the C / T value is 0.3 to 3, preferably 0.5 to 2, the content of the matting agent (C) can be adjusted.

Specifically, for example, when the coating film having a thickness of 1 μm to 20 μm is formed on the material steel sheet using the UV curable coating composition of the present invention, the present invention is within the range satisfying the C / T value. The content of the matting agent included in the UV curable paint composition may be 0.3 parts by weight to 60 parts by weight based on 100 parts by weight of the UV curable paint composition.

The present inventors have experimentally confirmed that even in the UV-curable coating composition containing the same amount of matting agent, the gloss controlled area is different depending on the thickness of the coating film produced using the coating composition. That is, as the thickness of the coating film increases, the content of the matting agent in a state capable of adjusting gloss by irradiating near infrared rays tends to increase.

Therefore, in the present invention, the C / T value, which is a relation between the content (C) of the quencher and the thickness (T) of the coating layer, may be 0.3 to 3, preferably 0.5 to 2. When the C / T value is less than 0.3, the content of the matting agent included in the coating layer is too small relative to the thickness of the coating layer, so that only a high gloss coating layer is always obtained. When the C / T value is more than 3, the coating layer Too much content of the matting agent included in the coating layer compared to the thickness, even if the gloss control through the near-infrared irradiation is always obtained only a low-gloss coating layer, it may be difficult to control the various gloss through near-infrared irradiation.

The UV curable coating composition of the present invention may include an oligomer, and the type of the oligomer is not particularly limited, but an acrylic oligomer may be preferable.

In the UV curable coating composition of the present invention, the oligomer may be included in 20 parts by weight to 90 parts by weight, preferably 30 parts by weight to 70 parts by weight based on 100 parts by weight of the UV curable paint composition. When the content of the oligomer is less than 20 parts by weight, as the photopolymerization reaction proceeds rapidly, the crosslinking density may increase and brittleness of the coating may increase. When the content of the oligomer exceeds 90 parts by weight, the photopolymerization reaction rate is lowered, making it difficult to control the crosslinking density. There is a possibility that a large amount of UV irradiation for curing is required or the UV irradiation time is prolonged.

In addition, in the UV curable coating composition of the present invention, the type of the oligomer is not particularly limited, but preferably at least one acrylic oligomer selected from the group consisting of urethane acrylate, epoxy acrylate and polyester acrylate. .

In addition, the weight average molecular weight of the oligomer in the present invention is not particularly limited, for example, may be 1000 to 5000, preferably 1000 to 3000.

In this specification, the weight average molecular weight means a polystyrene conversion value measured by GPC (gel permeation chromatography).

In the UV curable coating composition of the present invention, the photopolymerizable monomer may be included in an amount of 20 parts by weight to 90 parts by weight, preferably 30 parts by weight to 70 parts by weight, based on 100 parts by weight of the UV curable paint composition. When the content of the photopolymerizable monomer is less than 20 parts by weight, the photopolymerization reaction rate is lowered, making it difficult to control the crosslinking density, requiring a large amount of UV irradiation for curing the coating film, or a long UV irradiation time, and 90 parts by weight. If exceeded, as the photopolymerization reaction proceeds rapidly, the crosslinking density increases, which may increase the brittleness of the coating film.

In addition, in the UV curable coating composition of the present invention, the kind of the photopolymerizable monomer is not particularly limited, but may be preferably a monofunctional or polyfunctional acrylate monomer. The multifunctional acrylate monomer refers to a photopolymerizable acrylate monomer having two or more acrylate residues in a molecule.

The kind of the monofunctional acrylate monomer is not particularly limited, and examples thereof include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, sec-butyl (meth) acrylate, pentyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 2-ethylbutyl (meth ) Acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, isobonyl (meth) acrylate or isononyl (meth) acrylate, and the like. The above mixture can be used.

Specific examples of the polyfunctional acrylate monomers include hexanediol di (meth) acrylate, trimethylolpropanetrioxyethyl di (meth) acrylate, alkylene glycol di (meth) acrylate, and dialkylene glycol. Di (meth) acrylate, trialkylene glycol di (meth) acrylate, dicyclopentenyl di (meth) acrylate, dicyclopentenyloxyethyl di (meth) acrylate, neopentyl glycol di (meth) acrylic At least one selected from the group consisting of latex, dipentaerythritol hexa di (meth) acrylate, trimethylolpropane tri (meth) acrylate, and pentaerythritol tri (meth) acrylate, but is not limited thereto.

In the UV curable coating composition of the present invention, the photoinitiator may be included in 0.1 to 30 parts by weight, preferably 1 to 10 parts by weight based on 100 parts by weight of the UV curable paint composition. When the content of the photoinitiator is less than 0.1 parts by weight, the photopolymerization reaction does not occur, or the photopolymerization reaction occurs very slowly, so that curing of the coating film by UV irradiation may be impossible or the curing time may be prolonged. By the reaction, the photoinitiator is transferred to the radical form and remains, which may inhibit the photopolymerization reaction or lower the physical properties of the coating film.

In addition, in the UV curable coating composition of the present invention, the kind of the photoinitiator is not particularly limited, and although a short wavelength photoinitiator or a long wavelength photoinitiator can be selectively used depending on the ultraviolet lamp used for curing the coating composition, a ketone initiator Or an ester initiator etc. can be used, Preferably an epoxy ketone initiator, a phenyl ester initiator, etc. can be used.

In the UV-curable coating composition of the present invention, the content (C) of the matting agent is not particularly limited, and the range of satisfying the condition of the general formula 2 in consideration of the thickness (T) of the coating film produced using the coating composition Although it may be appropriately selected within, it may preferably be included in 0.3 parts by weight to 10 parts by weight, preferably 0.5 parts by weight to 6 parts by weight based on 100 parts by weight of the UV curable coating composition. When the content of the matting agent is less than 0.3 part by weight, the content of the matting agent is too small to irradiate near infrared rays, and thus, a low gloss coating layer cannot be obtained. When the content of the matting agent is greater than 10 parts by weight, the content of the matting agent is too large, even without irradiation of near infrared rays. Since only a low gloss coating layer is always obtained, various gloss adjustments through near-infrared irradiation can be difficult.

In the UV curable coating composition of the present invention, the kind of the matting agent is not particularly limited, and can be employed without limitation as long as it does not dissolve in the UV curable coating composition and can maintain a solid powder state. In the present invention, for example, at least one selected from the group consisting of silica, alumina, wax, ceramic, and synthetic polymer powder may be used as the matting agent, and preferably silica may be used, but is not limited thereto.

In the UV curable coating composition of the present invention, the average particle size (D) of the matting agent is not particularly limited, and the condition of the general formula (1) is satisfied in consideration of the thickness (T) of the coating film produced using the coating composition. Although appropriately selected within the range, it may be preferably 0.1 μm to 60 μm, preferably 0.5 μm to 30 μm.

The UV curable coating composition of the present invention may further include an additive together with an oligomer, a photopolymerizable monomer, a photoinitiator, and a quencher without departing from the object of the present invention, and the additive may include an antifoaming agent, a leveling agent, a dispersant, and an adhesive force. And at least one selected from the group consisting of enhancers.

The present invention is also a steel sheet; It relates to a steel sheet which is formed on one or both surfaces of the raw material steel sheet and includes a coating layer containing a cured product of the UV curable coating composition according to the present invention.

Hereinafter, with reference to the accompanying drawings, the steel sheet of the present invention will be described in detail.

1 and 2 are views showing a cross-sectional view of a steel sheet according to an embodiment of the present invention. As shown in Figure 1, the steel sheet 10 of the present invention is a material steel sheet (11); And a coating layer 12 formed on one surface of the material steel plate 11, and as shown in FIG. 2, the steel plate 20 of the present invention comprises: a material steel plate 11; And two coating layers 12 formed on both surfaces of the material steel plate 11.

The type of material steel sheet included in the steel sheet of the present invention is not particularly limited, but preferably one selected from the group consisting of a cold rolled steel sheet, a galvanized steel sheet, a zinc alloy plated steel sheet, an aluminum plated steel sheet, an aluminum alloy plated steel sheet, and a stainless steel sheet. The above is mentioned.

In the present invention, the coating layer formed on one or both surfaces of the raw material steel sheet may contain a cured product of the UV-curable coating composition according to the present invention described above. The details regarding the UV curable coating composition contained in the coating layer are the same as described above.

In the present invention, the thickness of the coating layer is not particularly limited and may be appropriately selected according to the use of the steel sheet, but may be preferably 1 μm to 20 μm. If the thickness of the coating layer is less than 1 μm, the corrosion resistance of the steel sheet is lowered, the gloss is lowered regardless of the use of a matting agent, and various gloss adjustments may be difficult. In addition, when the thickness of the coating layer exceeds 20 μm, cracks may occur in the coating layer during forming the steel sheet, and the adhesion of the coating layer may be deteriorated, thereby degrading workability. In addition, in order to make the thickness of the coating layer exceed 20 μm, as the quencher included in the UV curable coating composition, very coarse particles having an average particle size of more than 10 μm should be used, so that the content of the quencher is very high. Since the matting agent particles are easily settled, it is difficult to store the solution, and uniformity of the coating film may be deteriorated when the UV curable coating composition is continuously roll coated on the material steel sheet for a long time.

In addition, the steel sheet of the present invention may further include a coating layer formed between the material steel sheet and the coating layer.

3 and 4 are cross-sectional views of steel sheets according to other embodiments of the present invention. As shown in Figure 3, the steel sheet 30 of the present invention is a material steel sheet (11); A coating layer 12 formed on one surface of the material steel plate 11; And a coating layer 31 formed between the material steel sheet 11 and the coating layer 12, and as shown in FIG. 4, the steel sheet 40 of the present invention is a material steel sheet 11. ; Two coating layers 12 formed on both surfaces of the material steel plate 11; And two coating layers 31 formed between the material steel sheet 11 and the coating layer 12.

The type of the coating layer in the present invention is not particularly limited, but may be preferably at least one selected from the group consisting of a pretreatment layer, a primer layer and a coloring paint layer. When the coating layer has a structure of two or more layers, a structure laminated in the order of the pretreatment layer and the primer layer, or a structure laminated in the order of the pretreatment layer, the primer layer and the coloring paint layer may be preferable.

5 and 6 are views showing cross-sectional views according to one embodiment of the coating layer included in the steel sheet of the present invention. As shown in FIG. 5, the coating layer 31 of the present invention may have a structure in which the pretreatment layer 31a and the primer layer 31b are sequentially stacked, and as shown in FIG. The coating layer 31 may have a structure in which the pretreatment layer 31a, the primer layer 31b, and the coloring paint layer 31c are sequentially stacked.

When the coating layer included in the steel sheet of the present invention has the structure of the coating layer 31 shown in FIGS. 5 and 6, the pretreatment layer 31a may be laminated to contact the material steel sheet 11.

The present invention also comprises the steps of coating the UV-curable coating composition according to the present invention on one or both sides of the raw material steel sheet, heat treatment to adjust the surface gloss; And curing the UV curable coating composition through UV irradiation to form a coating layer.

The method of manufacturing a steel sheet according to the present invention can reduce the content of the quencher included in the UV curable paint composition, and may also be accompanied by a decrease in the content of the dispersant according to the decrease in the content of the quencher, thereby forming a coating film formed from the UV curable paint composition. While maintaining the basic physical properties of the layer, for example, corrosion resistance, processability and chemical resistance, etc., it is possible to implement the desired surface gloss according to the heat treatment, it is possible to implement a variety of gloss from a single UV curable coating composition.

The manufacturing method of the steel sheet of the present invention may include the step of coating the UV-curable coating composition according to the present invention on the raw material steel sheet, heat treatment to adjust the surface gloss. Specific contents of the material steel sheet and the UV curable coating composition are the same as described above.

In the present invention, the method for coating the UV-curable coating composition according to the present invention on the material steel sheet is not particularly limited, and means commonly known in the art may be employed without limitation, for example, a bar coater. Or a roll coater may be used.

After coating the UV-curable coating composition according to the present invention on the material steel sheet in the present invention, the desired surface gloss can be achieved by heat treatment.

In the present invention, after the UV-curable coating composition is coated on the material steel sheet, the heat treatment means performed to control the surface gloss is not particularly limited, and examples thereof include an induction heating method, hot air, infrared rays, and near infrared rays. Preferably, a near infrared ray is mentioned. When the near-infrared irradiation method is used as the heat treatment means in the present invention, by partially heating only the surface layer of the UV-curable coating composition coated on the material steel sheet, it is possible to easily adjust the surface gloss by controlling the near-infrared radiation intensity while minimizing the change of physical properties of the coating film. .

Specifically, when the near-infrared ray is irradiated to the UV curable coating composition coated on the material steel sheet, the surface of the coating is heated, the surface planarization effect by the tension may proceed. As the surface planarization is performed on the surface of the coating, an exposed portion of the matting agent included in the coating may increase, thereby reducing the surface gloss. At this time, as the amount of near-infrared rays irradiated to the coating increases, the surface is flattened, so that the exposed portion of the matting agent may be increased, so that the effect of lowering the surface gloss may be further improved.

That is, in the manufacturing method of the steel sheet of the present invention, various surface gloss can be realized by adjusting the irradiation amount of the near infrared ray during the irradiation of the near infrared ray. Specifically, the difference between the maximum glossiness and the minimum glossiness measured using a 60 degree glossmeter can be controlled to at least 30 by adjusting the irradiation amount of near infrared rays.

When the irradiation of the near infrared rays is not performed in the manufacturing method of the steel sheet of the present invention, the maximum glossiness can be realized, and when the irradiation amount of the near infrared rays is increased, the glossiness can be reduced and the minimum glossiness can be realized. That is, when manufacturing the steel sheet of the present invention using the UV-curable coating composition according to the present invention, from the single UV-curable coating composition to adjust the amount of near-infrared radiation according to the desired glossiness to produce a steel sheet having a variety of gloss can do.

In the present invention, the wavelength range of the near infrared ray irradiated to the coating is not particularly limited, but may be preferably 0.75 μm to 3 μm, more preferably 0.8 μm to 1.5 μm. When the wavelength of the near infrared ray is less than 0.75 μm, absorption efficiency may be lowered in the transparent UV curable coating composition because it is close to the visible light region, and when it exceeds 3 μm, latent heat control may be difficult by uniformly heating the entire coating film. The efficiency of absorbing infrared rays varies according to the components used in the paint, so it is necessary to change the irradiation intensity for each paint.

The method of manufacturing a steel sheet of the present invention may include a step of curing the surface gloss by heating and then irradiating and curing the UV curable coating composition with UV.

In the manufacturing method of the steel sheet of the present invention, by heating the UV-curable coating composition coated on the material steel sheet to adjust the exposed portion amount of the matting agent to achieve the desired surface gloss, when irradiated with UV, the photoinitiator is a radical UV curing is progressed by initiating a reaction between the acrylic oligomer and the photopolymerization monomer while forming a film, thereby forming a coating layer on the material steel sheet.

The method of irradiating UV to the UV curable coating composition in the present invention is not particularly limited, UV irradiation apparatus commonly known in the art can be employed without limitation, for example, UV lamp can be used.

7 is a view schematically showing a method of manufacturing a steel sheet according to one embodiment of the present invention. As shown in FIG. 7, (a) coating the UV curable coating composition according to the present invention on a material steel sheet, and (b) irradiating near-infra red (NIR) to the coating, the coating As the surface layer of water is heated, the surface planarization effect due to tension is advanced, and as a result, the exposed portion of the matting agent may increase as the matting agent buried in the coating is exposed to the outside. As the exposed portion of the matting agent is increased, the matting effect may be improved, and thus surface gloss may be lowered. (c) Subsequently, when the coating is irradiated with UV, curing proceeds as the matting agent is exposed, thereby forming a coating layer having a desired surface gloss.

Conventionally, in order to form a desired low gloss coating layer, the glossiness is controlled by controlling the content of the matting agent in the UV curable coating composition, and a dispersant for uniformly dispersing the same as the content of the matting agent increases. And resulted in solution stability and solution non-uniformity with the addition of dispersant.

However, according to the method for producing a steel sheet of the present invention, even if a small amount of matting agent is used, the glossiness can be adjusted as desired according to the amount of near-infrared radiation irradiation, thereby forming a desired low gloss coating layer, while providing excellent basic physical properties of the coating layer. I can keep it.

The method for manufacturing a steel sheet of the present invention may further include forming a coating layer on one or both surfaces of the raw steel sheet before coating the UV curable coating composition on the raw steel sheet.

In the manufacturing method of the steel sheet of the present invention, the type of the coating layer is not particularly limited, but may be preferably at least one selected from the group consisting of a pretreatment layer, a primer layer and a coloring paint layer. Specific details regarding the coating layer are the same as described above, and the method of forming the coating layer is not particularly limited, and methods commonly known in the art may be employed without limitation.

[ Example ]

Hereinafter, the present invention will be described in more detail with reference to the following examples and comparative examples, but the scope of the present invention is not limited by the following examples.

Example  One

(One) UV  Preparation of Curable Coating Composition

A liquid mixture was prepared by mixing 50 parts by weight of urethane acrylate, 35 parts by weight of isobornyl acrylate as a photopolymerizable monomer, 9 parts by weight of hydroxy cyclohexyl phenyl ketone as a photoinitiator, and 1 part by weight of polyester-modified polydimethyl siloxane leveling agent. , 1 part by weight of silica powder as a matting agent was mixed with the liquid mixture to prepare a UV curable coating composition. The average particle size of the silica powder was 2 μm.

(2) the material of steel plate UV  Coating of Curable Paint Composition

The UV-curable coating composition prepared above was coated with a roll coater so as to have a thickness of 2 μm after drying on a hot dip galvanized steel sheet after washing with degreasing.

(3) Coating layer  formation

UV-curable coating composition coated on the galvanized steel sheet to adjust the surface gloss by irradiating near infrared rays having a wavelength range of 0.8 ㎛ to 1.5 ㎛, then UV irradiation to cure the UV curable coating composition to a thickness of 2 ㎛ A layer was formed. This completed the steel plate in which the coating film layer was formed.

Example  2 to 14

(One) UV  Preparation of Curable Coating Composition

A UV curable coating composition was prepared in the same manner as in Example 1 except that the average particle size and content of the silica powder used as the matting agent was changed as shown in Table 1 below.

(2) the material of steel plate UV  Coating of Curable Paint Composition

The UV curable coating composition was coated on the raw material steel plate in the same manner as in Example 1 except that the coating thickness of the UV curable coating composition was changed as shown in Table 1 below.

(3) Coating layer  formation

Except having changed the thickness of the coating layer as shown in Table 1 below, it was carried out in the same manner as in Example 1 to complete a steel sheet having a coating layer.

The quencher content (C), quencher average particle size (D), thickness (T), C / T value and D / T value of the coating layer prepared in Examples 1 to 14 are summarized in Table 1 below. .

division Matting agent
Content (C) Matting agent
Average particle size (D) Coating layer
Thickness (T) C / T D / T





Example One One 2 2 0.5 One 2 One 5 2 0.5 2.5 3 2 2 2 One One 4 2 5 2 One 2.5 5 4 2 2 2 One 6 4 2 5 0.8 0.4 7 4 5 2 2 2.5 8 4 5 5 0.8 One 9 4 8 5 0.8 1.6 10 10 2 5 2 0.4 11 10 2 10 One 0.2 12 10 2 20 0.5 0.1 13 10 5 10 One 0.5 14 10 5 20 0.5 0.25 Matting agent: silica powder
Content Unit: parts by weight
Average particle size unit: μm
Coating layer thickness unit: μm

Comparative example  1 to 19

(One) UV  Preparation of Curable Coating Composition

A UV curable coating composition was prepared in the same manner as in Example 1 except that the average particle size and content of the silica powder used as the matting agent was changed as described in Table 2 below.

(2) the material of steel plate UV  Coating of Curable Paint Composition

The UV curable coating composition was coated on the raw material steel plate in the same manner as in Example 1 except that the coating thickness of the UV curable coating composition was changed as shown in Table 2 below.

(3) Coating layer  formation

Except having changed the thickness of the coating layer as shown in Table 1 below, it was carried out in the same manner as in Example 1 to complete a steel sheet having a coating layer.

The quencher content (C), quencher average particle size (D), thickness (T), C / T value and D / T value of the coating layer prepared in Comparative Examples 1 to 19 are summarized in Table 2 below. .

division Matting agent
Content (C) Matting agent
Average particle size (D) Coating layer
Thickness (T) C / T D / T








Comparative example One 0 - 5 0 - 2 0 - 5 0 - 3 0 - 10 0 - 4 0 - 20 0 - 5 One 2 5 0.2 0.4 6 One 2 10 0.1 0.2 7 One 2 20 0.1 0.1 8 One 8 5 0.2 1.6 9 One 8 10 0.1 0.8 10 One 8 20 0.05 0.4 11 2 2 10 0.2 0.2 12 2 2 20 0.1 0.1 13 2 8 10 0.2 0.8 14 2 8 20 0.1 0.4 15 4 2 20 0.2 0.1 16 4 8 20 0.2 0.4 17 10 2 2 5 One 18 10 5 2 5 2.5 19 10 8 2 5 4 Matting agent: silica powder
Content Unit: parts by weight
Average particle size unit: μm
Coating layer thickness unit: μm

Example  15

(1) Preparation of raw material steel plate with white colored coating layer

After mixing a polyester resin, a curing agent, TiO ₂ , which is a white pigment, and a diluting solvent to prepare a white colored paint, the white colored paint is degreased, coated with water and dried hot dip galvanized steel, and then heated by induction heating. Curing to prepare a raw material steel plate with a white coloring layer was formed.

(2) UV  Preparation of Curable Coating Composition

A UV curable coating composition was prepared in the same manner as in Example 1 except that the average particle size and content of the silica powder used as the matting agent was changed as described in Table 3 below.

(3) the material of steel plate UV  Coating of Curable Paint Composition

Using the hot-dip galvanized steel sheet formed with the prepared white colored coating layer, except that the coating thickness of the UV curable coating composition was changed as shown in Table 3 below, the white colored coating was carried out in the same manner as in Example 1 The UV curable coating composition was coated on the layered material steel sheet.

(4) Coating layer  formation

Except having changed the thickness of the coating layer as shown in Table 1 below, it was carried out in the same manner as in Example 1 to complete a steel sheet having a coating layer.

Example  16 to 24

The average particle size and content of the silica powder, which is a quencher included in the UV curable coating composition, is changed as shown in Table 3 below, and the thickness of the coating layer coated on the material steel plate on which the white colored paint layer is formed is shown in Table 3 below. Except for changing, the steel sheet in which the coating layer was formed was completed in the same manner as in Example 15.

The quencher content (C), quencher average particle size (D), thickness (T), C / T value and D / T value of the coating layer prepared in Examples 15 to 24 are summarized in Table 3 below. .

division Matting agent
Content (C) Matting agent
Average particle size (D) Coating layer
Thickness (T) C / T D / T



Example 15 2 2 2 One One 16 2 5 2 One 2.5 17 4 2 5 0.8 0.4 18 4 5 5 0.8 One 19 4 8 5 0.8 1.6 20 10 2 5 2 0.4 21 10 2 10 One 0.2 22 10 2 20 0.5 0.1 23 10 5 10 One 0.5 24 10 5 20 0.5 0.25 Matting agent: silica powder
Content Unit: parts by weight
Average particle size unit: μm
Coating layer thickness unit: μm

Comparative example  20 to 35

The average particle size and content of the silica powder, which is a quencher included in the UV curable coating composition, is changed as shown in Table 4 below, and the thickness of the coating layer coated on the material steel plate on which the white colored paint layer is formed is shown in Table 4 below. Except for changing, the steel sheet in which the coating layer was formed was completed in the same manner as in Example 15.

division Matting agent
Content (C) Matting agent
Average particle size (D) Coating layer
Thickness (T) C / T D / T






Comparative example 20 One 2 5 0.2 0.4 21 One 2 10 0.1 0.2 22 One 2 20 0.05 0.1 23 One 8 2 0.5 4 24 One 8 5 0.2 1.6 25 One 8 10 0.1 0.8 26 One 8 20 0.05 0.4 27 2 2 10 0.2 0.2 28 2 2 20 0.1 0.1 29 2 8 10 0.2 0.8 30 2 8 20 0.1 0.4 31 4 2 20 0.2 0.1 32 4 8 20 0.2 0.4 33 10 2 2 5 One 34 10 5 2 5 2.5 35 10 8 2 5 4 Matting agent: silica powder
Content Unit: parts by weight
Average particle size unit: μm
Coating layer thickness unit: μm

The physical properties of the steel sheets prepared in Examples and Comparative Examples were measured as follows.

1. Glossiness measurement

In manufacturing the steel sheets of the above Examples and Comparative Examples, in the process of adjusting the surface gloss by irradiating near-infrared, the surface gloss was adjusted by irradiating near-infrared while adjusting the intensity of irradiation of near-infrared in three steps. The near-infrared irradiation apparatus was designed and manufactured by the present inventors, and it was confirmed through experiments that a large change in glossiness appeared when irradiated with an intensity of 45%, 52%, and 60% based on the maximum output 100%. Therefore, the near-infrared irradiation intensity was fixed to the above three levels of intensity to investigate near-infrared rays. The prepared steel sheet was measured using a 60 degree glossmeter. In the case of the steel sheet manufactured without irradiating near infrared rays, the maximum glossiness was shown. In the steel sheet manufactured by irradiating near infrared rays with the highest strength of 60%, the minimum glossiness was shown. It summarized and described.

2. Coating adhesion measurement

The steel sheets prepared in Examples and Comparative Examples were cross-cut by 10 pieces each horizontally and vertically at intervals of 1 mm to make 100 cells, and then subjected to 6 mm height Eriksen processing, and then to a painted surface. Using a test cellophane tape (Nichiban N405, Nichiban Co., Ltd.) was adhered to the 100 cells and then peeled off to measure the degree of peeling of the coating layer and the presence of powdering. The results are shown in Table 5 below. It summarized and described.

<Evaluation of coating adhesion>

(Double-circle): The number of cells in which the coating film layer peeled is less than 10, and powdering does not generate | occur | produce.

(Circle): The number of cells in which the coating film layer peeled is 10-50, and powdering does not generate | occur | produce.

(Triangle | delta): The number of cells in which the coating film layer peeled is less than 10, and powdering generate | occur | produces.

X: The number of the cells in which the coating film layer peeled is more than 10, and powdering generate | occur | produces.

The measurement results of the physical properties of the steel sheets prepared in Examples and Comparative Examples are shown in Tables 5 and 6, respectively.

division Coating adhesion Glossiness maximum at least maximum minimum










Example One ◎ 140 98 42 2 ○ 137 87 50 3 ○ 142 55 87 4 ○ 137 41 96 5 ○ 93 49 44 6 ◎ 146 57 89 7 △ 86 41 45 8 ◎ 140 43 97 9 ○ 91 43 48 10 ○ 95 44 51 11 ○ 150 56 94 12 ◎ 150 102 48 13 △ 140 42 98 14 ○ 139 89 50 15 ◎ 83 37 46 16 ◎ 80 30 50 17 ◎ 89 38 51 18 ◎ 86 31 55 19 ◎ 61 30 31 20 ◎ 63 31 32 21 ◎ 90 38 52 22 ◎ 91 59 32 23 ◎ 87 31 56 24 ◎ 89 57 32

division Coating adhesion Glossiness maximum at least maximum minimum














Comparative example One ◎ 136 134 2 2 ◎ 141 140 One 3 ◎ 144 143 One 4 ◎ 143 140 3 5 ◎ 148 144 4 6 ◎ 150 144 6 7 ◎ 150 144 6 8 ○ 89 86 3 9 ○ 92 89 3 10 ◎ 92 88 4 11 ◎ 145 144 One 12 ◎ 147 144 3 13 ○ 91 87 4 14 ◎ 89 86 3 15 ◎ 148 144 4 16 ◎ 92 87 5 17 × 41 38 3 18 × 43 37 6 19 × 43 37 6 20 ◎ 91 90 One 21 ◎ 90 88 2 22 ◎ 89 89 0 23 ◎ 54 42 12 24 ◎ 56 55 One 25 ◎ 55 55 0 26 ◎ 58 56 2 27 ◎ 91 88 3 28 ◎ 91 90 One 29 ◎ 59 56 3 30 ◎ 57 57 0 31 ◎ 92 90 2 32 ◎ 58 57 One 33 ◎ 32 30 2 34 ◎ 31 29 2 35 ◎ 32 28 4

As shown in Tables 5 and 6, in Examples 1 to 24 according to the present invention, D / T and C / T are respectively 0.1 to 3; And it satisfies all of the range of 0.3 to 3, it can be seen that by controlling the irradiation intensity of the near-infrared irrespective of the type of material steel plate used, it is possible to control the difference between the maximum glossiness and the minimum glossiness to 30 or more. . On the other hand, in Comparative Examples 1 to 35 not according to the present invention, since at least one or more of D / T and C / T is out of a specific range in the present invention, the difference between the maximum glossiness and the minimum glossiness was less than 10, near-infrared It can be seen that high or low glossiness is maintained irrespective of irradiance intensity, and gloss control through near-infrared irradiance intensity is difficult.

In addition, it can be seen that the coating film adhesion evaluation differs depending on the type of raw material steel sheet used. That is, in Examples 15 to 24 and Comparative Examples 20 to 35 in which the coating layer was formed on the raw material steel plate coated with the white coloring layer, the adhesion between the coating layer and the white coloring layer was excellent and almost no coating layer peeling occurred. In the case of Examples 1 to 14 and Comparative Examples 1 to 19 in which the coating film layer was directly formed on the raw material steel sheet, the coating film adhesion was generally good.

Therefore, the UV curable coating composition of the present invention is D / T and C / T of 0.1 to 3, respectively; And by controlling in the range of 0.3 to 3, while it is possible to implement a variety of gloss by adjusting the irradiation intensity of the near infrared, it can be confirmed that the basic physical properties of the coating film, such as coating film adhesion strength is generally excellent.

10,20,30,40: steel sheet 11: material steel sheet
12: coating layer 31: coating layer
31a: pretreatment layer 31b: primer layer
31c: colored paint layer NIR: near infrared ray
UV: UV

Claims (23)

Oligomers; Photopolymerizable monomers; Photoinitiators; And a quencher, and satisfying the conditions of the following Formulas 1 and 2
[Formula 1]
0.1 ≤ D / T ≤ 3
[Formula 2]
0.3 ≤ C / T ≤ 3
In Formulas 1 and 2, D represents the average particle size (unit: μm) of the quencher, T represents the thickness (unit: μm) of the coating film formed by UV curing the UV curable coating composition, C is The content (unit: parts by weight) of the matting agent included in the UV curable coating composition is shown, and the parts by weight represent a weight ratio. The method of claim 1,
UV curable coating composition having a D / T of 0.5 to 1.5. The method of claim 1,
UV curable coating composition having a C / T of 0.5 to 2. The method of claim 1,
The oligomer is 20 to 90 parts by weight based on 100 parts by weight of the UV curable coating composition UV curable coating composition. The method of claim 1,
The oligomer is at least one UV curable coating composition selected from the group consisting of urethane acrylate, epoxy acrylate and polyester acrylate. The method of claim 1,
The photopolymerizable monomer is UV curable paint composition comprising 20 parts by weight to 90 parts by weight based on 100 parts by weight of the UV curable paint composition. The method of claim 1,
The photopolymerizable monomer is a UV curable coating composition which is a monofunctional or polyfunctional acrylate monomer. The method of claim 1,
The photoinitiator is UV curable paint composition comprising 0.1 to 30 parts by weight based on 100 parts by weight of the UV curable paint composition. The method of claim 1,
The photoinitiator is at least one UV curable coating composition selected from the group consisting of a ketone initiator and an ester initiator. The method of claim 1,
The matting agent is UV curable paint composition comprising 0.3 to 10 parts by weight with respect to 100 parts by weight of the UV curable paint composition. The method of claim 1,
The matting agent is a UV curable coating composition to maintain a solid powder state in the UV curable coating composition. The method of claim 1,
The matting agent is at least one UV curable coating composition selected from the group consisting of silica, alumina, wax, ceramic and synthetic polymer powder. The method of claim 1,
The matting agent is UV curable coating composition having an average particle size of 0.1 ㎛ to 30 ㎛. Material steel plate;
A steel sheet, which is formed on one or both surfaces of the raw material steel sheet and comprises a coating layer containing a cured product of the UV curable coating composition according to any one of claims 1 to 13. 15. The method of claim 14,
The steel sheet is at least one selected from the group consisting of a cold rolled steel sheet, a galvanized steel sheet, a zinc alloy plated steel sheet, an aluminum plated steel sheet, an aluminum alloy plated steel sheet, and a stainless steel sheet. 15. The method of claim 14,
Steel sheet whose thickness of a coating layer is 1 micrometer-20 micrometers. 15. The method of claim 14,
A steel sheet further comprising a coating layer formed between the raw steel sheet and the coating layer. The method of claim 17,
The coating layer is at least one steel sheet selected from the group consisting of a pretreatment layer, a primer layer and a coloring paint layer. Coating the UV-curable coating composition according to any one of claims 1 to 13 on one or both sides of the raw material steel sheet, heat treatment to adjust the surface gloss; And
A method of manufacturing a steel sheet comprising the step of curing the UV curable coating composition through UV irradiation to form a coating layer. The method of claim 19,
The heat treatment is a method for producing a steel sheet is carried out by irradiating near infrared rays. 21. The method of claim 20,
Near-infrared rays have a wavelength of 0.75 µm to 3 µm. The method of claim 19,
A method of manufacturing a steel sheet further comprising the step of forming a coating layer on one or both sides of the material steel sheet before coating the UV curable coating composition on the material steel sheet. The method of claim 22,
The coating layer is at least one selected from the group consisting of a pretreatment layer, a primer layer and a coloring paint layer.

Images