KR102365398B1 - Photo-curable composition for pre-coated metal and method for manufacturing pre-coated metal using the same - Google Patents

Abstract

Disclosed are a photocurable coating composition for a freshly-prepared steel sheet and a method for manufacturing a freshly-prepared steel sheet using the same. The photo-curable paint composition for a pre-coated steel sheet includes a photoinitiator; fluorine-modified urethane acrylate resin; leveling agent; UV absorbers; and a solvent; may include.

Description

Photo-curable coating composition for pre-coated steel sheet and method for manufacturing pre-coated steel sheet using the same

The present disclosure relates to a photo-curable coating composition for a pre-coated steel sheet and a method for manufacturing a pre-coated steel sheet using the same.

In general, a pre-coated metal (PCM) refers to a steel sheet manufactured by a pre-coating method of pre-coating before forming and processing the steel sheet. The pre-coated steel sheet has the advantage of being able to mass-produce in a short time and produce uniform products compared to the post-coating method in which the steel sheet is formed and processed and then painted. In this regard, Korean Patent Publication No. 10-2020274 has been presented with respect to a method of manufacturing a PCM steel sheet.

A conventional pre-coated steel sheet was manufactured by coating a thermosetting top coat on a surface-treated steel sheet and thermosetting to form a top coat layer, coating a photocurable paint on the formed top coat layer, and photocuring. However, the coating film formed by the thermosetting paint has good processability, but has poor gloss and hardness, and the coating film formed by the photocurable paint has the disadvantage that it can be produced only when an expensive ultraviolet irradiation facility is equipped in the production line. That is, when a steel company manufactures a lead sheet steel sheet, if there is no UV irradiation facility on the production line of the steel company, the formation of a photocured coating film on the steel sheet is limited.

Therefore, there is a need for a new technology that supplements the luster and hardness, which are the disadvantages of existing thermosetting paints, and can manufacture a steel sheet with a photocurable coating layer without UV irradiation equipment in the steel company when manufacturing the pre-coated steel sheet.

The technical idea of the present disclosure is to solve the above problems, and it is an object of the present disclosure to provide a technique for improving gloss and hardness, which are disadvantages of conventional thermosetting paints, while maintaining processability, which is an advantage of existing thermosetting paints.

Another object of the present disclosure is to provide a technology capable of manufacturing a pre-coated steel sheet with a photo-curing coating layer without UV irradiation equipment when a steel manufacturer manufactures the pre-coated steel sheet.

In addition, another object of the present disclosure is to provide a technology for reducing cost and improving workability by omitting a process of forming a coating layer by a thermosetting type paint when manufacturing a pre-coated steel sheet.

The problems to be solved by the present invention are not limited to the above problems, and other technical problems not mentioned will be clearly understood by those of ordinary skill in the art to which the present invention belongs from the following description.

In order to achieve this object, as an embodiment of the present invention, a photo-curable paint composition for a fresh-coated steel sheet includes a photoinitiator; fluorine-modified urethane acrylate resin; leveling agent; UV absorbers; and a solvent; may include.

In addition, the photoinitiator is 2-5 wt%, the fluorine-modified urethane acrylate resin is 42.5-50 wt%, the leveling agent is 0.5-1 wt%, the UV absorber is 0.5-1.5 wt%, the solvent is 42.5-50 wt% It may be provided in weight %.

In addition, the fluorine-modified urethane acrylate resin may be prepared as a copolymer of a fluorine-based compound, an isocyanate compound, and an acrylate containing at least one hydroxyl group.

In addition, the fluorine-based compound is 2-nonafluorobutyl ethanol, 2-tridecafluorohexyl ethanol, 2-heptadecafluorooctyl ethanol, 2-heenaicosafluorodecyl ethanol, 2,3-difluorobenzyl alcohol , 2-fluorobenzyl alcohol, 1-pentafluorophenyl ethanol, and at least one of 2-trifluoromethylbenzyl alcohol may be provided.

In order to achieve this object, as another embodiment of the present invention, a method for manufacturing a pre-coated steel sheet includes an adhesive layer forming step of forming an adhesive layer by applying an adhesive to one surface of the steel sheet; a transfer step of laminating and transferring the film to the steel plate so that the coating layer is transferred from the film having the coating layer formed by applying the above-described coating composition and photocuring to the steel plate; and a film removal step of peeling and removing the film attached to the steel plate, wherein the film removed in the film removal step may be provided as a film in a state separated from the coating layer.

In addition, in the adhesive layer forming step, the adhesive layer may be formed by heating and drying the adhesive applied to one surface of the steel sheet.

In addition, in the transfer step, the primer layer previously formed on the upper surface of the coating layer is attached to the adhesive layer, and in the film removal step, the adhesion between the coating layer and the film is relatively compared to the adhesion between the primer layer and the adhesive layer. Due to the small formation, the coating layer remains on the upper surface of the steel sheet, and the film may be removed in a state separated from the coating layer.

The means for solving the above-described problems are merely exemplary, and should not be construed as limiting the present invention. In addition to the exemplary embodiments described above, there may be additional embodiments described in the drawings and detailed description.

As described above, according to various embodiments of the present invention, by transferring the photocurable coating layer formed on the film to the steel plate when the steel manufacturer manufactures the pre-coated steel plate, the photocurable coating layer is layered without a separate UV irradiation equipment. Since the formed pre-coated steel sheet can be manufactured, there is an effect of reducing the cost required for the facility and operation of the UV irradiation equipment and increasing the space utilization at the work site.

In addition, according to various embodiments of the present invention, since the thermosetting paint is not used, the process of forming the coating layer by the thermosetting paint is omitted, thereby reducing costs and improving workability.

In addition, according to various embodiments of the present invention, the workability is excellent even without forming a coating layer made of a thermosetting paint on the steel sheet, and the coating film has excellent properties such as curability, transferability, gloss, adhesion, solvent resistance, hardness, and weather resistance. It is possible to manufacture a fresh galvanized steel sheet.

Effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims.

1 is a flow chart illustrating a method of manufacturing a lead sheet steel sheet according to an embodiment of the present invention.

A preferred embodiment of the present invention will be described in more detail with reference to the accompanying drawings, but already known technical parts will be omitted or compressed for the sake of brevity of description.

It should be noted that references to "one" or "an" embodiment of the invention herein are not necessarily to the same embodiment, and they mean at least one.

As used herein, "(meth) acryl" means acryl or methacrylic.

In the following examples, the singular expression includes the plural expression unless the context clearly dictates otherwise.

In the following embodiments, terms such as include or have means that the features or components described in the specification are present, and the possibility that one or more other features or components may be added is not excluded in advance.

In the following embodiments, when it is said that a part such as a film, region, or component is on or on another part, not only when it is directly on the other part, but also another film, region, component, etc. is interposed therebetween. Including cases where there is

In cases where certain embodiments may be implemented otherwise, a specific process sequence may be performed different from the described sequence. For example, two processes described in succession may be performed substantially simultaneously, or may be performed in an order opposite to the order described. That is, each step of the method described herein may be appropriately performed in any order unless otherwise stated in the specification or clearly contradicted by context.

The term "about" used in front of a numerical value throughout this specification is used in or close to the numerical value when manufacturing and material tolerances inherent in the stated meaning are presented, and to aid understanding of the present application, the term "about" Absolute figures are used to prevent unreasonable exploitation of the stated disclosure by unscrupulous infringers.

<Description of photo-curable paint composition for pre-coated steel sheet>

The photocurable paint composition for a fresh-coated steel sheet according to an embodiment of the present invention may include a photoinitiator, a fluorine-modified urethane acrylate resin, a leveling agent, an ultraviolet absorber, and a solvent.

In one embodiment, the photoinitiator is a compound that hardens the coating film by initiating photopolymerization upon irradiation with ultraviolet rays, and as the photoinitiator that can be used in one embodiment, a photocleavage type or hydrogen absorption type photoinitiator may be applied. For example, the photoinitiator may be provided with at least one selected from the group consisting of 1-hydroxycyclohexylphenylketone and benzophenone, but is not limited thereto, and other known types of photoinitiators may be used.

In addition, examples of commercially available photoinitiators in one embodiment may include, but are not limited to, Irgacure 184, Irgacure 651, Iragacure 754 (Ciba Gage Co.) and the like.

And, the content of the photoinitiator according to an embodiment may be applied to 2 to 5% by weight. As a specific example, the content of the photoinitiator may be provided in about 2% by weight, about 3% by weight, about 4% by weight or about 5% by weight. Also, the content of the photoinitiator may be in the range of one or more of the above values and less than or equal to one of the above values.

For example, the content of the photoinitiator ranges from about 2% to about 3% by weight, from about 3% to about 4% by weight, from about 4% to about 5% by weight, or from about 2% to about 5% by weight. can be provided with The photoinitiator according to an embodiment may maintain the curability and yellowing resistance of the coating film at an excellent level within the above range.

If the amount of the photoinitiator is less than 2% by weight, the hardenability and solvent resistance may decrease due to poor curability of the coating film, and if it exceeds 5% by weight, there is a risk of yellowing of the coating film. It is preferable to be

In one embodiment, the fluorine-modified urethane acrylate resin may be applied as a copolymer of a fluorine-based compound, an isocyanate compound, and an acrylate containing at least one hydroxyl group. Here, the fluorine-based compound is 2-nonafluorobutyl ethanol, 2-tridecafluorohexyl ethanol, 2-heptadecafluoro octyl ethanol, 2-heenaicosafluorodecyl ethanol, and 2,3-difluorobenzyl alcohol. , 2-fluorobenzyl alcohol, 1-pentafluorophenyl ethanol, and at least one of 2-trifluoromethylbenzyl alcohol may be provided.

In one embodiment, the isocyanate compound may be applied as at least one of aromatic, aliphatic and cycloaliphatic diisocyanate. For example, the isocyanate compound is 4,4'-diphenylmethane diisocyanate, 1,5'-naphthalene diisocyanate, 1,4'-phenylene diisocyanate, hexamethylene diisocyanate, 1,4'-cyclohexane diisocyanate. , 4,4'-dicyclohexylmethane diisocyanate and at least one selected from isophorone diisocyanate may be provided.

In one embodiment, the hydroxyl group-containing acrylate may be applied as a (meth)acrylate containing one or more hydroxyl groups. For example, hydroxyl group-containing (meth)acrylate is 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 1,4-cyclohexanedimethanol mono (meth)acrylate, 1-chloro-2-hydr Roxypropyl (meth) acrylate, diethylene glycol mono (meth) acrylate, 1,6-hexanediol mono (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol penta (meth) acrylate, Neopentyl glycol mono (meth) acrylate, trimethylolpropane di (meth) acrylate, trimethylolethane di (meth) acrylate, 2-hydroxy-3-phenyloxypropyl (meth) acrylate, 4- At least one selected from hydroxycyclopentyl (meth) acrylate, 4-hydroxycyclohexyl (meth) acrylate and cyclohexanedimethanol mono (meth) acrylate may be applied.

In one embodiment, the content of the fluorine-modified urethane acrylate resin may be applied to 42.5 to 50% by weight. As a specific example, the content of the fluorine-modified urethane acrylate resin is about 42.5% by weight, about 43% by weight, about 44% by weight, about 45% by weight, about 46% by weight, about 47% by weight, about 48% by weight, about 49 It may be provided in wt% or about 50 wt%. In addition, the content of the fluorine-modified urethane acrylate resin may be in the range of at least one of the above values and less than or equal to one of the above values.

For example, the content range of the fluorine-modified urethane acrylate resin is about 42.5 wt% to about 45 wt%, about 43 wt% to about 46 wt%, about 44 wt% to about 47 wt%, about 45 wt% to about 45 wt% 48 wt%, about 46 wt% to about 49 wt%, about 47 wt% to about 50 wt%, or about 42.5 wt% to about 50 wt%. The fluorine-modified urethane acrylate resin according to an embodiment may maintain physical properties such as transferability, weather resistance, leveling property, and processability of the coating film at an excellent level within the above range.

If the amount of the fluorine-modified urethane acrylate resin is less than 42.5 wt%, there is a risk of deterioration in transferability and light resistance, and if it exceeds 50 wt%, leveling properties and workability are lowered and compatibility with other components is lowered and the image quality (glossy) Since this may decrease, the content of the fluorine-modified urethane acrylate resin is preferably carried out within the above-mentioned range. In one embodiment, in order to improve physical properties such as hardness, light resistance, and weather resistance of a coating film formed by an existing urethane acrylate resin, a fluorine-modified urethane acrylate resin that is a copolymer of a fluorine-based compound, an isocyanate compound, and an acrylate containing at least one hydroxyl group By including in the coating composition, there is an advantage in that physical properties such as hardness, light resistance, and weather resistance of the coating film are improved.

In one embodiment, the leveling agent may maintain the workability of the coating material and the smoothness of the coating film at an appropriate level. The type of leveling agent that can be used in one embodiment may be provided with at least one selected from the group consisting of silicone-based, fluorine-based and polyether-based leveling agents, but is not limited thereto.

The leveling agent according to an embodiment is preferable in terms of maintaining the smoothness of the coating film at an excellent level to apply a silicone-based leveling agent such as silicone, polydimethylsiloxane, polyether-modified polydimethylsiloxane, and polymethylalkylsiloxane among the above-mentioned types. Do.

In addition, examples of commercially available leveling agents in one embodiment include BYK-300, BYK-306, EFKA-3033, EFKA-3034, EFKA-3035, etc. of BYK, but other types of known leveling agents not mentioned above may be used. It is also possible to use a leveling agent. It is preferable to use BYK-300, EFKA-3033, or the like among the above-described types of the leveling agent in terms of securing the physical properties of the coating film.

And, the content of the leveling agent according to an embodiment may be applied to 0.5 to 1% by weight. As a specific example, the content of the leveling agent may be about 0.5% by weight, about 0.6% by weight, about 0.7% by weight, about 0.8% by weight, about 0.9% by weight or about 1% by weight. In addition, the content of the leveling agent may be in the range of at least one of the above values and less than or equal to one of the above values.

For example, the content range of the leveling agent is from about 0.5% to about 0.8% by weight, from about 0.6% to about 0.9% by weight, from about 0.7% to about 1% by weight, or from about 0.5% to about 1% by weight. range may be provided. The leveling agent according to an embodiment may maintain surface wetting and adhesion at an excellent level within the above range.

If the leveling agent is less than 0.5% by weight, there is a fear that the leveling property may be slightly deteriorated due to deterioration of surface wetting properties, and if it exceeds 1% by weight, the transferability may be reduced when transferring the coating layer to the steel sheet due to the slip property of the coating film. Therefore, the content of the leveling agent is preferably applied within the above-described range.

In one embodiment, the ultraviolet absorber may be applied to at least one selected from benzophenone-based, benzotriazole-based, salicylate-based, cyanoacrylate-based, oxanilide-based and triazine-based, but is not limited thereto and is not limited thereto. Any kind of UV absorber may be used.

In one embodiment, as an example of a commercially available UV absorber, Ciba's Tinuvin 1130, Tinuvin 292, etc. may be used. And, the content of the ultraviolet absorber according to an embodiment may be applied to 0.5 to 1.5% by weight. As a specific example, the content of the ultraviolet absorber is about 0.5% by weight, about 0.6% by weight, about 0.7% by weight, about 0.8% by weight, about 0.9% by weight, about 1% by weight, about 1.1% by weight, about 1.2% by weight, about 1.3 It may be provided in weight %, about 1.4 weight %, or about 1.5 weight %. In addition, the content of the ultraviolet absorber may be in the range of at least one of the above values and less than or equal to one of the above values.

For example, the content range of the ultraviolet absorber is from about 0.5% to about 0.8% by weight, from about 0.6% to about 0.9% by weight, from about 0.7% to about 1% by weight, from about 0.8% to about 1.1% by weight, from about 0.9 wt% to about 1.2 wt%, from about 1 wt% to about 1.3 wt%, from about 1.1 wt% to about 1.4 wt%, from about 1.2 wt% to about 1.5 wt% or from about 0.5 wt% to about 1.5 wt% range may be provided. The ultraviolet absorber according to an embodiment may maintain weather resistance and curability at an excellent level within the above range.

If the UV absorber is less than 0.5 wt%, the effect of improving the weather resistance of the coating film is insignificant. It is preferable to apply within.

In one embodiment, the solvent may be provided with at least one selected from methyl ethyl ketone, methyl isobutyl ketone, 1-methyl-2-pyrrolidinone, cyclohexanone, acetone, xylene, methyl acetate, ethyl acetate, and propyl acetate. , It is not limited to the above-described examples, and other known solvents may also be used.

The content of the solvent according to an embodiment may be applied in an amount of 42.5 to 50% by weight. As a specific example, the content of the solvent is about 42.5% by weight, about 43% by weight, about 44% by weight, about 45% by weight, about 46% by weight, about 47% by weight, about 48% by weight, about 49% by weight or about 50% by weight % may be provided. In addition, the content of the solvent may be in the range of at least one of the above numerical values and less than or equal to one of the above numerical values.

For example, the content range of the solvent is about 42.5 wt% to about 46 wt%, about 43 wt% to about 47 wt%, about 44 wt% to about 48 wt%, about 45 wt% to about 49 wt%, about 46 wt% to about 50 wt%, about 47 wt% to about 50 wt%, or about 42.5 wt% to about 50 wt%. The solvent according to an embodiment may maintain the coating workability at an excellent level by controlling the viscosity of the coating composition within the above range.

If the solvent is less than 42.5 wt%, the viscosity of the coating composition may increase excessively and coating workability may be reduced. If it exceeds 50 wt%, curing takes a lot of time and there is a risk of cost increase. It is preferably carried out within the above-described range.

<Description of the method for manufacturing a pre-coated steel sheet using a photo-curable coating composition for pre-coated steel sheet>

A method for manufacturing a pre-glazed steel sheet according to an embodiment of the present invention will be described in accordance with the flowchart shown in FIG.

1. Adhesive layer forming step <S101>

In this step, an adhesive layer may be formed by applying an adhesive to the upper surface of the steel sheet. In one embodiment, the adhesive applied to the steel sheet may be applied as a temperature-sensitive adhesive. Here, the steel sheet may be a stainless steel sheet, an aluminum plated steel sheet, a hot-dip galvanized steel sheet, an electro galvanized steel sheet or a zinc aluminum plated steel sheet, but is not limited to the above-described example.

In one embodiment, the temperature sensitive adhesive may include a polyester polyol and a blocked isocyanate compound. The blocked isocyanate is a block of the isocyanate reactive group so that the reaction with the hydroxyl group does not proceed at room temperature, and only when a certain temperature is reached, the isocyanate reactive group becomes reactive and adhesiveness can be expressed.

In this step, when the adhesive applied to one side of the steel sheet is heated and dried at a constant temperature (for example, 220 to 250 ° C.), the isocyanate groups blocked in the adhesive are activated to form an adhesive layer, and the formed adhesive layer can exhibit adhesive force. In one embodiment, as an example of a commercially available thermosetting adhesive, Tokyu's P-24 or the like may be used.

2. Transcription step <S102>

In this step, the coating layer may be transferred by laminating the film on the adhesive layer of the steel sheet so that the coating layer is transferred from the film having the coating layer formed by applying and photocuring the above-described photocurable coating composition for pre-coated steel sheet. Here, the film may be made of a material of polyethylene terephthalate, polyethylene, polyvinyl chloride, polypropylene, or polycarbonate.

On the other hand, before this step is performed, the coating layer forming step in which the above-described photocurable coating composition for pre-coated steel sheet is applied and photocured to form a coating layer on one surface of the film may be performed separately. In the coating layer forming step, the above-described photocurable coating composition may be applied to one surface of the film to form a coating layer on the surface of the film, and the coating layer may be formed with a coating film thickness of 5 to 7 μm. As a specific example, the thickness of the dry coating film coated on the surface of the film may be about 5 μm, about 6 μm, or about 7 μm. In addition, the thickness of the dry coating film may be applied in a range of at least one of the above values and less than or equal to one of the above values. For example, the range of the thickness of the dry coating film coated on the film may be provided in a range of about 5 μm to about 7 μm, about 6 μm to about 7 μm, or about 5 μm to about 7 μm. If the thickness of the dry coating film to be coated is less than 5㎛, physical properties such as hardness, gloss, and weather resistance of the coating film may be reduced. Since there is a risk of rising, the thickness of the coating film is preferably carried out within the above-described range. The coating method for forming a coating layer on the surface of the film is not limited to any specific method, and known coating methods such as bar coating, slit coating, dip coating, roll coating, spin coating, spray coating, dipping method, impregnation method, gravure coating, etc. Among them, those skilled in the art can arbitrarily select and apply. In the coating layer forming step, ultraviolet rays may be irradiated to the coating layer at an amount of 300 to 500 mJ/cm 2 using an ultraviolet irradiation device (eg, a mercury lamp). When the amount of light during UV irradiation is less than 300 mJ/cm 2 , curability is not good, and when it exceeds 500 mJ/cm 2 , curing proceeds excessively, the workability of the coating film is deteriorated, and there is a possibility that a crack phenomenon may occur in the coating film. In addition, during the coating layer forming step, a primer layer may be formed by applying a primer to the upper surface of the photocured coating layer and drying it. Here, as the primer, a polyester-based primer, an epoxy-based primer or an acrylic primer may be used, and commercially available primers include AD-76H5 of Dongyang Morton.

Accordingly, in the present transfer step, the coating layer may be transferred while the primer layer previously formed on the upper surface of the coating layer of the film is attached to the adhesive layer formed on the upper surface of the steel sheet.

3. Film removal step <S103>

In this step, it can be removed by peeling the film attached to the steel plate in step S102. That is, since the coating layer attached to the surface of the film in step S102 is transferred to the steel plate, the film removed in this step is separated from the coating layer. This is because the adhesion formed between the coating layer and the film is relatively small compared to the adhesion between the primer layer and the adhesive layer, so in this step, the coating layer remains attached to the primer layer and remains on the upper surface of the steel sheet, and the film is separated from the coating layer It can be peeled off and removed.

Hereinafter, the present invention will be described in more detail through specific examples and experimental examples. Since the following Examples and Experimental Examples are merely examples to help the understanding of the present invention, the scope of the present invention is not limited or limited thereto.

1. Synthesis of fluorine-modified urethane acrylate resin

In a round-bottom flask equipped with a stirrer, 300 g of 2-fluorobenzyl alcohol, 500 g of isophorone diisocyanate, 1500 g of 2-hydroxypropyl acrylate, and 0.1 g of dibutyltin dilaurylate were added. After maintaining the reaction temperature at 70~80℃ and reacting until the NCO concentration of the reactant reaches the theoretical NCO concentration, the reaction temperature is lowered to 50℃ and 0.25 g of hydroquinone and 0.25 g of phenol as a polymerization inhibitor Nocyanin was added, and 300 g of pentaerythritol triacrylate was added to advance the reaction. After the input was completed, the reaction temperature was maintained at 70-80°C for 8-9 hours, and the -NCO peak was confirmed with infrared spectroscopy (FT-IR) until the completely disappeared, and the reaction was completed to obtain a fluorine-modified urethane acrylate resin. .

2. Preparation of photo-curable paint composition for pre-coated steel sheet

Mix in the same composition as in Table 1 below, but mix each photoinitiator, fluorine-modified urethane acrylate resin, leveling agent, UV absorber and solvent at the content (unit: g) shown in Table 1 below in a 1L container, and mix for 1 hour After stirring for a while, a photocurable paint composition for a fresh steel sheet was completed.

ingredient Example
One Example
2 Example
3 Example
4 Example 5 comparative example
One comparative example
2 comparative example
3 ¹ photoinitiator 2 3 5 5 5 6 4 One ² Fluorine-modified urethane acrylate resin 50 45 48 42.5 50 51 41.5 49 ³ leveling agent 0.5 One One One One One 1.5 0 ⁴ UV absorbers 0.5 One One 1.5 1.5 0.5 2 0 ⁵ solvent 47 50 45 50 42.5 41.5 51 50
main)
1: Photoinitiator - Irgacure 184 (Shiba Gage Co.)
2: Fluorine-modified urethane acrylate resin (Jogwang Paint)
3: Leveling agent (BYK-300, BYK)
4: UV absorber (Tinuvin-1130, Ciba)
5: Solvent - methyl ethyl ketone

3. Production of test film and steel plate

<Test film>

Bar coating the coating composition prepared with the composition shown in Table 1 on a 10cm X 10cm size polyethylene terephthalate film using a bar coater so that the thickness of the dry film becomes 6㎛, and 30~ in an oven at 60~80℃ After removing the solvent by heating for 60 seconds, the coating layer was cured by irradiating ultraviolet rays with a light quantity of 500 mJ/cm 2 under a general atmospheric environment using an ultraviolet irradiation device (mercury lamp) to prepare a test film.

<Steel plate for testing>

Bar coating the coating composition prepared with the composition shown in Table 1 on a 10cm X 10cm size polyethylene terephthalate film using a bar coater so that the thickness of the dry film becomes 6㎛, and 30~ in an oven at 60~80℃ After removing the solvent by heating for 60 seconds, using an ultraviolet irradiation device (mercury lamp) to cure the coating layer by irradiating ultraviolet rays at a light quantity of 500mJ/cm2 in a general atmospheric environment to form a coating layer on the surface of the film, and use a bar coater Thus, a polyester-based primer was applied so that the thickness of the dry coating film was 1 μm, and the primer layer was formed on the coating layer by heating in an oven at 60 to 80° C. for 30 to 60 seconds.

Thereafter, a thermosetting adhesive was applied to a galvanized steel sheet having a size of 10 cm X 10 cm using a bar coater so that the thickness of the dry film became 15 μm, and then dried by heating at 220 to 250° C. to form an adhesive layer on the surface of the steel sheet. Immediately after heating and drying was completed, the coating layer was transferred by attaching a primer layer of the film to the upper surface of the adhesive layer. After 30 minutes had elapsed, the film was peeled off and removed from the steel plate, and the production of the steel plate for testing was completed.

4. Test and evaluation methods

For the test specimens and steel sheets produced as described above, the coating film sclerosis, transferability, gloss, adhesion, solvent resistance, hardness, weather resistance and workability were evaluated through the method described below, and the results are shown in Table 2.

Experimental environment conditions

The test environment, that is, the place where the test is conducted, should be at a temperature of 20±2℃ and humidity of 65±5% (hereinafter referred to as 'room temperature'), in a place without direct sunlight and with very little gas, steam, dust and ventilation. In principle, those left for more than 72 hours after painting were used for the experiment.

Hardenability evaluation

It was checked whether a nail scratch occurred by scraping the cured coating film of the test film with a nail. If a nail scratch occurred, it was evaluated as poor curability, and if it did not occur, it was evaluated as good.

company-wide evaluation

When the film was peeled from the steel sheet during manufacture of the steel sheet for testing, it was visually evaluated whether the coating layer attached to the film was transferred to the steel sheet. That is, if the coating layer did not remain on the surface of the peeled film, transferability was evaluated as good, and if the coating layer remained on the surface of the peeled film, the transferability was evaluated as poor.

Gloss rating

The gloss of the coating film was evaluated by measuring the steel sheet for testing with a gloss meter (60°Gloss, BYK-Gardner Gloss Meter). In evaluation, the larger the numerical value measured by the polisher, the better the gloss effect.

Adhesion evaluation

A cross-cutting test method was performed on the coating film of the steel sheet for testing, and a glass tape was used at this time. That is, the film or layer formed on the specimen is cut into 100 checkered slices with a size of 1 mm * 1 mm, and a glass tape is attached to the slice. gender was evaluated.

Solvent resistance evaluation

After methyl ethyl ketone was applied to the gauze, the gauze was rubbed 50 times by applying a certain force to the steel sheet for testing on which the coating film was formed, and then the number of times the gauze was rubbed until the coating film was peeled off to reveal the substrate was measured. When the number of times of rubbing was 10 or less, when the coating film was peeled off, it was evaluated as 'NG'.

Hardness evaluation

Hardness evaluation was evaluated whether there was an abnormality in the coating film of the test steel sheet when moving 2 cm by applying a 45° inclination and a load of 750 g using a Mitsubishi Pencil. In 5 evaluations, the maximum pencil hardness value when there were no scratches in all 5 times was recorded.

CCET (Cross Cut Erichsen Test) evaluation

Fix the test steel plate made with 100 checkered patterns in the size of 1mm*1mm to the Ericsson tester, apply a load at a rate of 0.5mm per second. If there were no cracks, peeling, or swelling of the coating film within 6.0 mm of the progressed depth, it was evaluated as good, and if abnormality occurred in the coating film, it was evaluated as bad.

Weatherability evaluation

The weather resistance test was conducted using a weather resistance tester (Weather-O-meter, Irradiance: 300-400 nm, 66W/m ² ) to measure the ΔE value (weather resistance value) after leaving the test steel sheet for 500 hours. It was determined that the smaller the measured weather resistance value, the better the weather resistance.

Processability evaluation

Processability was evaluated using a milling vise. That is, it was checked whether cracks occurred on the surface of the steel sheet folded in half after folding the steel sheet for testing in half, putting another steel sheet for testing in between, inserting it in a milling vise and pressing it. At this time, if one other steel plate was folded in half and a crack occurred, it was denoted as 1T, if two went in and a crack occurred, 2T, and if three went in and a crack occurred, it was denoted as 3T. It was evaluated that the lower the number indicated, the better the workability (flexibility) of the steel sheet for the test because the smaller the number of other steel sheets inserted between the half-folded steel sheets, the more the half-folded steel sheets could be bent.

division Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Comparative Example 3 hardenability Good Good Good Good Good Good error error warrior Good Good Good Good Good Good error Good Polish 91 90 92 91 92 90 80 85 adherence 100/100 100/100 100/100 100/100 100/100 100/100 80/100 90/100 solvent resistance 50 episodes 50 episodes 50 episodes 50 episodes 50 episodes 50 episodes Episode 12 30 episodes Hardness F F F F F F HB HB CCET
(6mm) Good Good Good Good Good error error Good weather resistance 1.55 1.43 1.89 1.76 1.45 2.55 3.23 2.35 machinability 1T 1T 1T 1T 1T 3T 1T 2T

As shown in Table 2, it can be confirmed that Examples 1 to 5 of the present invention have excellent overall surface properties such as curability, transferability, gloss, adhesion, solvent resistance, hardness, weather resistance and processability of the coating film. there is. And, through the experimental results of Comparative Examples 1 to 3, it can be seen that the surface properties of the coating film are reduced when the content of each component included in the coating composition exceeds or is less than the input amount range for each component.

5. Additional fabrication of test specimens and steel plates and evaluation of physical properties

<Test film>

The coating composition prepared in Example 1 of Table 1 was bar-coated on a polyethylene terephthalate film having a size of 10 cm X 10 cm using a bar coater, and heated in an oven at 60 to 80 ° C for 30 to 60 seconds. After the solvent was removed, the coating layer was cured by irradiating ultraviolet rays with a light quantity of 200 to 600 mJ/cm 2 under a general atmospheric environment using an ultraviolet irradiation device (mercury lamp) to prepare a test film. The thickness of the coating film and the amount of light of the photocurable coating layer were set as the numerical values shown in Tables 3 to 7 below, and the results of evaluation of physical properties of each specimen based on the above-described method for evaluating physical properties were described in Tables 3 to 7.

<Steel plate for testing>

The coating composition prepared in Example 1 of Table 1 was bar-coated on a polyethylene terephthalate film having a size of 10 cm X 10 cm using a bar coater, and heated in an oven at 60 to 80 ° C for 30 to 60 seconds. After the solvent is removed, the coating layer is cured by irradiating ultraviolet rays with a light quantity of 200 to 600 mJ/cm 2 under a general atmospheric environment using an ultraviolet irradiation device (mercury lamp) to form a coating layer on the surface of the film, and then using a bar coater to dry the coating film. A polyester-based primer was applied to a thickness of 1 μm and heated in an oven at 60 to 80° C. for 30 to 60 seconds to form a primer layer on the coating layer.

Thereafter, a thermosetting adhesive was applied to a galvanized steel sheet having a size of 10 cm X 10 cm using a bar coater so that the thickness of the dry film became 15 μm, and then dried by heating at 220 to 250° C. to form an adhesive layer on the surface of the steel sheet. Immediately after heating and drying was completed, the coating layer was transferred by attaching a primer layer of the film to the upper surface of the adhesive layer. After 30 minutes had elapsed, the film was peeled off and removed from the steel plate, and the production of the steel plate for testing was completed. The thickness of the coating film and the amount of light of the photocurable coating layer were set as the numerical values shown in Tables 3 to 7 below, and the results of evaluation of physical properties of each specimen based on the above-described method for evaluating physical properties were described in Tables 3 to 7.

amount of light 200mJ/cm2 film thickness Experimental Example 1
(2㎛) Experimental Example 2
(5㎛) Experimental Example 3
(6㎛) Experimental Example 4
(7㎛) Experimental Example 5
(10㎛) hardenability error error error error error warrior error error error error error Polish 80 84 85 85 88 adherence 80/100 75/100 70/100 80/100 75/100 solvent resistance NG NG NG NG NG Hardness B B B B B CCET
(6mm) error error error error error weather resistance 3.23 3.50 3.75 4.10 4.25 machinability 2T 3T 3T 3T 4T

amount of light 300mJ/cm2 film thickness Experimental Example 6
(2㎛) Experimental Example 7
(5㎛) Experimental Example 8
(6㎛) Experimental Example 9
(7㎛) Experimental Example 10
(10㎛) hardenability error Good Good Good Good warrior error Good Good Good Good Polish 75 91 92 92 93 adherence 100/100 100/100 100/100 100/100 100/100 solvent resistance Episode 15 50 episodes 50 episodes 50 episodes 50 episodes Hardness B F F F F CCET
(6mm) Good Good Good Good error weather resistance 1.35 1.49 1.59 1.65 3.72 machinability 1T 1T 1T 1T 4T

amount of light 400mJ/cm2 film thickness Experimental Example 11
(2㎛) Experimental Example 12
(5㎛) Experimental Example 13
(6㎛) Experimental Example 14
(7㎛) Experimental Example 15
(10㎛) hardenability Good Good Good Good Good warrior error Good Good Good Good Polish 75 92 92 92 93 adherence 100/100 100/100 100/100 100/100 100/100 solvent resistance Episode 15 50 episodes 50 episodes 50 episodes 50 episodes Hardness B F F F F CCET
(6mm) Good Good Good Good error weather resistance 1.24 1.45 1.59 1.73 3.45 machinability 1T 1T 1T 1T 4T

amount of light 500mJ/cm2 film thickness Experimental Example 16
(2㎛) Experimental Example 17
(5㎛) Experimental Example 18
(6㎛) Experimental Example 19
(7㎛) Experimental Example 20
(10㎛) hardenability Good Good Good Good Good warrior error Good Good Good Good Polish 75 90 92 92 90 adherence 100/100 100/100 100/100 100/100 100/100 solvent resistance Episode 15 50 episodes 50 episodes 50 episodes 50 episodes Hardness B F F F F CCET
(6mm) Good Good Good Good error weather resistance 1.32 1.55 1.59 1.59 3.35 machinability 1T 1T 1T 1T 4T

amount of light 600mJ/cm2 film thickness Experimental Example 21
(2㎛) Experimental Example 22
(5㎛) Experimental Example 23
(6㎛) Experimental Example 24
(7㎛) Experimental Example 25
(10㎛) hardenability Good Good Good Good Good warrior error Good Good Good Good Polish 75 91 92 92 91 adherence 100/100 100/100 100/100 100/100 100/100 solvent resistance Episode 15 50 episodes 50 episodes 50 episodes 50 episodes Hardness B F F F F CCET
(6mm) Good Good error error error weather resistance 1.32 1.54 1.51 1.66 3.26 machinability 1T 2T 2T 2T 4T

As can be seen from the results of the physical property evaluation in Tables 3 to 7, the coating composition and the fresh-coated steel sheet prepared according to the examples of the present invention are optimal when the coating film thickness is 5 to 7 μm under the condition of 300 to 500 mJ/cm 2 of light. It satisfies the required physical properties, and it can be seen that the physical properties deteriorate when it is out of the range of light quantity and thickness of the film.

As described above, according to various embodiments of the present invention, by transferring the photocurable coating layer formed on the film to the steel plate when the steel manufacturer manufactures the pre-coated steel plate, the photocurable coating layer can be layered without a separate UV irradiation equipment. Since the formed pre-coated steel sheet can be manufactured, there is an effect of reducing the cost required for the facility and operation of the UV irradiation equipment and increasing the space utilization at the work site.

In addition, according to various embodiments of the present invention, since the thermosetting paint is not used, the process of forming the coating layer by the thermosetting paint is omitted, thereby reducing costs and improving workability.

In addition, according to various embodiments of the present invention, the workability is excellent even without forming a coating layer made of a thermosetting paint on the steel sheet, and the coating film has excellent properties such as curability, transferability, gloss, adhesion, solvent resistance, hardness, and weather resistance. It is possible to manufacture a fresh galvanized steel sheet.

As described above, the detailed description of the present invention has been made by way of examples, but since the above-described exemplary embodiments have only been described with preferred examples of the present invention, it should not be understood that the present invention is limited only to the above examples. No, the scope of the present invention should be understood as the following claims and their equivalents.

Claims (7)

photoinitiators;
fluorine-modified urethane acrylate resin;
leveling agent;
UV absorbers; and
solvent; including,
The photoinitiator is 2-5 wt%, the fluorine-modified urethane acrylate resin is 42.5-50 wt%, the leveling agent is 0.5-1 wt%, the UV absorber is 0.5-1.5 wt%, the solvent is 42.5-50 wt% characterized in that it is provided in %
A photo-curable coating composition for a fresh galvanized steel sheet. delete According to claim 1,
The fluorine-modified urethane acrylate resin is characterized in that it is prepared as a copolymer of a fluorine-based compound, an isocyanate compound, and an acrylate containing at least one hydroxyl group.
A photo-curable coating composition for a fresh galvanized steel sheet. 4. The method of claim 3,
The fluorine-based compound is 2-nonafluorobutyl ethanol, 2-tridecafluorohexyl ethanol, 2-heptadecafluorooctyl ethanol, 2-heenaicosafluorodecyl ethanol, 2,3-difluorobenzyl alcohol, 2-fluorobenzyl alcohol, 1-pentafluorophenyl ethanol, and 2-trifluoromethylbenzyl alcohol, characterized in that provided with at least one
A photo-curable coating composition for a fresh galvanized steel sheet. An adhesive layer forming step of forming an adhesive layer by applying an adhesive to one surface of the steel sheet;
[Claim 5] Transfer by laminating the film on the steel plate so that the coating layer is transferred from the film having the coating layer formed by applying the coating composition according to any one of claims 1 to 3 and photocuring to the steel plate. step; and
a film removal step of peeling and removing the film attached to the steel plate;
The film removed in the film removal step is a film in a state separated from the coating layer,
The amount of light during photocuring of the coating layer is 300 ~ 500mJ / ㎠, characterized in that the coating film thickness of the coating layer is 5 ~ 7㎛
A method for manufacturing a fresh galvanized steel sheet. 6. The method of claim 5,
In the adhesive layer forming step, the adhesive layer is formed by heating and drying the adhesive applied to one surface of the steel sheet.
A method for manufacturing a fresh galvanized steel sheet. 6. The method of claim 5,
In the transfer step, the primer layer previously formed on the upper surface of the coating layer is attached to the adhesive layer, and in the film removal step, the adhesive force between the coating layer and the film is relatively small compared to the adhesive force between the primer layer and the adhesive layer. Due to the formation, the coating layer remains on the upper surface of the steel sheet, and the film is removed in a state separated from the coating layer.
A method for manufacturing a fresh galvanized steel sheet.

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