KR102179180B1 - Photo-curable coating composition for pre-coated metal and preparation method for pre-coated metal using the same - Google Patents

Abstract

The present invention relates to a photo-curable coating composition for a lead-length steel sheet and a method of manufacturing a colored lead-length steel sheet using the same.
According to an embodiment of the present invention, the method of manufacturing a colored lead-coated steel sheet using a photo-curable coating composition for a lead-long steel sheet and a photo-curable coating composition for a lead-length steel sheet, which is the present inventor It can be greatly reduced and has excellent effects in improving workability and energy saving by light curing. In addition, the introduction of the double curing system (LED + mercury) has an excellent effect in improving the adhesion problem caused by uncuring by solving the curing failure that occurs when applying color to the existing UV paint.
In addition, it is possible to improve physical properties such as surface hardness and scratch resistance by including an inorganic filler in the photo-curable coating composition for a lead-length steel sheet according to the present invention.

Description

Photo-curable coating composition for pre-coated metal and preparation method for pre-coated metal using the same}

The present invention relates to a photo-curable coating composition for a lead-length steel sheet and a method of manufacturing a colored lead-length steel sheet using the same.

The thermosetting paint applied to the conventional PCM steel plate could not implement a beautiful appearance such as high screening properties. Recently, UV-curable paints are widely used in transparent products that require mass production due to eco-friendly and fast curing speed, such as PVC (Polyvinyl Chloride), PET (Polyethylene terephthalate), and wood. Recently, as consumers' demands for color have increased, requests for colored UV-curable paints are increasing by giving colors to UV (Ultraviolet) curable paints. UV-curable paints are paints that are cured by ultraviolet light of 200 to 400 nm, and there is a limit to the application of colored UV-curable paints because mercury lighting alone causes curing failure when the content of colored pigments increases.

In addition, PCM (Pre-Coated Metal) steel plate is used not only in various industrial fields such as railways, vehicles, ships, and road facilities, but also for electric and electronic products, especially organic light-emitting diodes (LEDs) and active-matrix organic light-emitting diodes. Light-emitting diode), liquid crystal display (LCD), plasma display (PDP), etc., as it can be applied to various products such as kitchen, living room products, architectural interior materials, and flooring. It is essential to improve various properties such as improvement.

In Korean Patent Publication No. 2012-0115027 (a) 100 parts by weight of a diol containing a carboxyl group; 600 to 800 parts by weight of polyol; And reacting 600 to 800 parts by weight of an isocyanate compound to prepare a polyurethane prepolymer I at the terminal of the isocyanate group. (b) 100 parts by weight of the obtained prepolymer I; And reacting 0.3 to 1.5 parts by weight of a polyfunctional monomer to prepare a crosslinked polyurethane prepolymer II. (c) neutralizing the prepolymer II by adding 1 to 5 parts by weight of an amine to 100 parts by weight of the obtained prepolymer II, and then adding water to prepare a polyurethane aqueous dispersion resin I; And (d) 100 parts by weight of the obtained water dispersion resin I; And 20 to 150 parts by weight of water to 100 parts by weight of the polyurethane water dispersion resin prepared, including the step of reacting 1 to 5 parts by weight of a chain extender to prepare a chain-extended polyurethane water dispersion resin II; 10 to 20 parts by weight of an inorganic binder; 2 to 10 parts by weight of a metal chelating agent; 1 to 5 parts by weight of adhesion promoter; Disclosed is a coating composition for PCM comprising 1 to 10 parts by weight of an anticorrosive agent and 0.1 to 2 parts by weight of an antifoaming agent.

The UV-curable transparent paint for PCM is a solvent-free type, and there is a limit to the selection of pigments for color realization. For example, in the case of applying a color pigment, there is a problem in that there is a curing problem when UV curing of an ultraviolet curable paint is applied, and when applied, the coating film is increased (5 to 20 μm), and thus workability and hardness properties are deteriorated.

It is an object of the present invention to provide a pre-curing technology to improve physical properties by mixing a reinforcing agent in a photo-curable coating composition for a lead-coated steel sheet and overcome hardening obstacles that may occur during the manufacture of colored lead-coated steel sheets.

In order to achieve the above object, a photocurable coating composition for a lead-coated steel sheet according to an embodiment of the present invention includes: a urethane (meth)acrylate prepolymer, which is a copolymer of at least one diisocyanate compound and at least one hydroxyl group-containing (meth)acrylate; (Meth)acrylate monomer; Photoinitiators; Inorganic fillers; And colored pigments.

In addition, the inorganic filler may be selected from the group consisting of silica, titania, alumina, zirconia, tin, zinc, antimony, indium, and mixtures thereof.

The inorganic filler may be characterized in that it is included in 3 to 5 parts by weight.

The colored pigment may be characterized in that it is included in 5 to 10 parts by weight.

The manufacturing method of the colored lead sheet steel sheet according to another aspect of the present invention for achieving the above object

(a) applying a photocurable coating composition for a lead-length steel plate on a steel plate substrate;

(b) Primary curing of the photocurable coating composition for the lead-length steel sheet by irradiating a single wavelength light beam to the photo-curable coating composition for the lead-length steel sheet with LED lighting while pressing the applied photocurable coating composition for the lead-length steel sheet using a pressing means. Step to do;

(c) secondary curing the photocurable coating composition for the lead-length steel sheet by irradiating ultraviolet rays to the pre-cured photocurable coating composition for the lead-length steel sheet; and the photo-curable coating composition for the lead-length steel sheet includes: It may be characterized in that it is a photo-curable coating composition for a lead-length steel sheet according to any one of claims 5.

According to an embodiment of the present invention, the method of manufacturing a colored lead-coated steel sheet using a photo-curable coating composition for a lead-long steel sheet and a photo-curable coating composition for a lead-length steel sheet according to the present invention include volatile organic compounds generated when using an existing heat-curable lead-long steel sheet coating agent. It can be greatly reduced and has excellent effects in improving workability and energy saving by light curing. In addition, the introduction of the dual curing system (LED + mercury) has an excellent effect in improving the adhesion problem caused by uncuring by solving the curing failure that occurs when applying color to the existing UV paint.

In addition, it is possible to improve physical properties such as surface hardness and scratch resistance by including an inorganic filler in the photo-curable coating composition for a lead-length steel sheet according to the present invention.

A preferred embodiment of the present invention will be described in more detail, but technical parts that are already well known will be omitted or compressed for conciseness of description.

< For lead-length steel plate Photo-curable coating composition>

One aspect of the present inventors, the photocurable coating composition for lead-coated steel sheet (PCM) is a urethane (meth)acrylate prepolymer, (meth)acrylic, a copolymer of at least one diisocyanate compound and at least one hydroxyl group-containing (meth)acrylate. It includes a rate monomer, a photoinitiator, an inorganic filler and a colored pigment.

Urethane (meth) acrylate prepolymer (URETHANE (METH) ACRYLATE COMPOUND Prepolymer) is used to have a weight average molecular weight of 500 to 2000, and an average urethane bonds of 6 to 22 per molecule. This is because if the weight average molecular weight is less than 500, adhesion is lowered, and if it exceeds 2000, the leveling is lowered due to an increase in viscosity, resulting in a problem in realizing a beautiful appearance.

Here, the urethane (meth)acrylate prepolymer is a copolymerization of at least one diisocyanate compound and at least one hydroxyl group-containing (meth)acrylate, and by using such a urethane (meth)acrylate prepolymer, workability and scratch resistance It is possible to manufacture a photo-curable coating composition for a lead-length steel sheet that can improve. There are several methods of introducing double bonds at both ends of a urethane prepolymer substituted with diisocyanate, but 2 mol of hydroxyl group-containing (meth)acrylate is reacted with 1 mol of diisocyanate. It is preferable to use the method of making. The hydroxyl group-containing (meth)acrylate used at this time has 2 to 6 carbons in the alkyl group, and 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth) Acrylate (2-hydroxypropyl (meth)acrylate), 2-hydroxybutyl (meth)acrylate, pentaerythritol tri-(meth)acrylate (Pentaerythritol tri-(meth)acrylate) One of them may be selected, or a mixture thereof may be used.

As the diisocyanate compound used in the photocurable coating composition for lead sheet steel sheet, aliphatic, alicyclic and aromatic diisocyanate compounds can all be used, among which isophorone diisocyanate (ISOPHORONE DI-ISOCYANATE), 2,4-toluene diisocyanate (2,4-toluene diisocyanate) and its isomers, 1,6-hexamethylene diisocyanate, lysine diisocyanate, trimethylhexamethylene diisocyanate, 2,2 -Bis-4'-propane isocyanate (2,2-Bis-4'-propane isocyanate), 6-isopropyl-1,3-phenyl diisocyanate (6-isopropyl-1,3-phenyl diisocyanate,), bis ( 2-isocyanate ethyl)-fumarate (Bis (2-isocyanatoethyl) -fumarate), 1,6-hexane diisocyanate (1,6-hexane diisocyanate), 4,4'-biphenylene diisocyanate (4,4'- biphenylene diisocyanate), 3,3′-dimethylphenylene diisocyanate (3,3′-dimethylphenylene diisocyanate), 3,3′-dimethyl-4,4′-diphenylmethane diisocyanate (3,3′-dimethyl-4, 4'-diphenylmethane diisocyanate), p-phenylenediisocyanate, m-phenylene diisocyanate, 1,5-naphthalene diisocyanate, 1,4- Among xylene diisocyanate (1,4-xylene diisocyanate), 1,3-xylene diisocyanate (1,3-xylene diisocyanate), and 4,4′-dicyclohexylmethane diisocyanate (4,4'-Dicyclohexylmethane diisocyanate) One of them may be selected or a mixture thereof may be used, and among them, 4,4′-dicyclohexylmethane diisocyanate and its isomers, 1,6-hexamethylene diisocyanate, and isophorone diisocyanate may be selected. It is preferable to use or a mixture thereof.

By using a photocurable resin containing a urethane (meth)acrylate prepolymer and (meth)acrylate monomer synthesized by copolymerizing a diisocyanate compound with a hydroxyl group-containing (meth)acrylate in the lead-length steel plate coating composition, scratch resistance Appearance such as castle and leveling is improved, and photo-curing is possible, resulting in reduction of working time and energy saving.

As the (meth)acrylate monomer diluted in the urethane (meth)acrylate prepolymer, a monofunctional monomer having one (meth)acrylate group and a polyfunctional monomer having two or more (meth)acrylate groups may be used.

Monofunctional monomers include diethylaminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, t-octyl (meth) acrylate (t-octyl (meth) acrylate), N,N-dimethyl (meth) acrylate (N, N-dimethyl (meth) acrylate), N-vinylcaprolactam, N-vinylpyrrolidone , Isobutoxy (meth) acrylamide, Diacetone (meth) acrylamide, Isobornyl (meth) acrylate, tricyclodecanyl (Meth) acrylate (Tricyclodecanyl (meth) acrylate), dicyclopentanyl (meth) acrylate, dicyclopentadiene (meth) acrylate (Dicyclopentadiene (meth) acrylate), methoxypolypropylene Glycol (meth)acrylate (Dicyclopentadiene (meth) acrylate), methoxypolyethylene glycol (meth) acrylate, ethoxyethoxyethyl (meth) acrylate (2-ETHOXYETHOXY ETHYL ACRYLATE) Methacrylate ), Methoxyethylene glycol (meth) acrylate, Polypropylene glycol mono (meth) acrylate, Polyethylene glycol mono (meth) acrylate mono (meth) acrylate), phenoxyethyl (meth) acrylate ), Cyclohexyl (meth) acrylate, Benzyl (meth) acrylate, Epoxy diethylene glycol (meth) acrylate , Butoxyethyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, stearyl (meth) acrylate, octa Decyl (meth) acrylate (Styryl (meth) acrylate), lauryl (meth) acrylate (Octadecyl (meth) acrylate), dodecyl (meth) acrylate (Dodecyl (meth) acrylate), isodecyl (meth) acrylic Isodecyl (meth) acrylate, Nonyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and isoamyl (meth) acrylate (Isoamyl (meth) acrylate), t-butyl (meth) acrylate, isobutyl (meth) acrylate 9Isobutyl (meth) acrylate), butyl (meth) acrylate ), isopropyl (meth) acrylate, propyl (meth) acrylate, ethyl (meth) acrylate, methyl (meth) acrylate Either one of methyl (meth) acrylates or a mixture thereof may be used.

Polyfunctional monomers include trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, trimethylolpropane EO modified triacrylate (Ethoxylated trimethylolpropane triacrylate), dipentaerythritol pentaacrylate (DIPENTAERYTHRITOL PENTAACRYLATE), dipentaerythritol hexaacrylate, ethylene glycol di (meth) acrylate (Ethylene dimethacrylate), dipropylene glycol di (meth) Acrylate (DIPROPYLENE GLYCOL DIMETHACRYLATE), 1,6-hexanediol di(meth)acrylate (1,6-Hexanediol dimethacrylate), tripropylene glycol dimethacrylate (Tripropylene glycol dimethacrylate), trimethylolpropanetrioxyethyl Select one of (meth)acrylate (Trimethylolpropane trioxyethyl (meth) acrylate), tricyclodecane dimethanoldi (meth) acrylate ((octahydro-4,7-methano-1H-indenediyl)bis(methylene) bismethacrylate) Alternatively, or a mixture thereof may be used.

In the photocurable coating composition for a lead-length steel sheet according to the present invention, it is preferable to use a monomer having 3 or more (meth)acrylate groups per molecule in order to improve curability and increase the hardness of the coating film as a diluted monomer. For example, isobornyl (meth)acrylate, pentaerythritol triacrylate, pentaerythritol EO-modified triacrylate, trimethylolpropane EO-modified triacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate It is preferable to use such as.

The diisocyanate compound and the hydroxyl group-containing (meth)acrylate have already been described in detail in the above description of the photocurable coating composition for lead-length steel sheets, so hereinafter, the content ratio and photoinitiator, inorganic The fillers and colored pigments will be described in detail.

It is preferable that the urethane (meth) acrylate prepolymer included in the present inventors photocurable coating composition for a lead-length steel sheet contains 30 to 70 parts by weight, based on the total weight of the photocurable coating composition for a lead-length steel sheet. This is a problem that if the urethane (meth)acrylate prepolymer is contained in less than 30 parts by weight, the content of oligomer is low, resulting in poor curability and adhesion, and if it is included in more than 70 parts by weight, the viscosity of the paint is high and it becomes too flexible, resulting in poor scratch resistance. This is because it occurs.

In addition, it is preferable that the (meth)acrylate monomer contained in the photocurable coating composition for a lead-length steel sheet according to the present invention contains 20 to 40 parts by weight based on the total weight of the photocurable coating composition for a lead-length steel sheet. This is because if the (meth)acrylate monomer is included in less than 20 parts by weight, the viscosity of the composition becomes too high and the hardness of the coating film decreases, and if it is included in more than 40 parts by weight, the adhesion is poor and the processability is caused by brittleness. .

On the other hand, the photocurable coating composition for a lead-length steel sheet according to the present invention is to accelerate the curing speed by curing with ultraviolet rays, and may include a photoinitiator for ultraviolet curing. Photoinitiators include 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-2-phenyl-acetophenone (2,2-Dimethoxy-2-phenylacetophenone), benzaldehyde, and anthraquinone. ), 3-methylacetophenone, 4-chlorobenzophenone, 4,4'-dimethoxybenzophenone, benzoin propyl ether ), Benzoin ethyl ether, 1-(4-isopropyl-phenol)-2-hydroxy-2-methylpropan-1-one (1- (4-isopropyl-phenol) -2-hydroxy -2-methylpropan-1-on), thioxanthen-9-one, benzophenone, 2,4,6-trimethylbenzoyl-diphenylphosphine (2,4,6-TRIMETHYLBENZOYLDIPHENYLPHOSPHINE) any of One or a mixture of these may be used.

In addition, commercially supplied photoinitiator products such as Irgacure184, Irgacure651, Irgacure500, Irgacure819, Irgacure907, Irgacure1800 (Shiba Geiggi), Darocure1116, Darocure1173 (Merck), Lucirine LR8728 (BASF), Micure HP-8, TPO ,BK-6,BP (Miwon Corporation), etc. can be used.

Such a photoinitiator is preferably contained in an amount of 2.5 to 7.5 parts by weight based on the total weight of the photocurable coating composition for a lead-length steel sheet.If the photoinitiator is included in less than 2.5 parts by weight, curability by ultraviolet rays decreases, and when it is included in excess of 7.5 parts by weight This is because too much photocuring takes place, resulting in poor adhesion.

In order to improve the scratch resistance of the surface, the photo-curable coating composition for the present inventors may include an inorganic filler, which is a filler for inorganic particles. By using an inorganic filler, it is possible to improve scratch resistance by increasing the hardness of the coating layer on the surface of the coating layer. It is preferable that these inorganic particles have an average particle diameter of about 10 to 60 nanometers.

Inorganic fillers that can be used in the photo-curable coating composition for the present inventors are silica (Silicon dioxide), titania (Titanium dioxide), alumina (ALUMINA), zirconia (Zirconia), tin (Tin), zinc (zinc), antimony ( antimony), indium, etc., and at least one or more of them may be mixed and used. Among these, it is particularly preferable to use silica, titania, alumina, and zirconia. In addition, these inorganic particles are preferably modified with a functional group capable of photocuring on the surface of the particle, that is, an acrylate group.

If such inorganic filler is contained in less than 5 parts by weight, it is difficult to improve scratch resistance, and if it is included in more than 10 parts by weight, curability decreases, resulting in weakened coating strength of the coating layer, and haze occurs in the coating film due to immiscibility. A problem occurs. Therefore, it is preferable that the inorganic filler is included in an amount of 5 to 10 parts by weight.

The photo-curable coating composition for a lead-coated steel sheet according to the present invention may contain a colored pigment to realize color. For color implementation, it is preferable to include 5 to 15 parts by weight of an organic pigment and an inorganic pigment, but when it is less than 5 parts by weight, it is difficult to realize color due to weak concealment, and when it is included in more than 15 parts by weight, curability decreases and adhesion is weakened. Occurs.

Hereinafter, examples of preparing a urethane (meth)acrylate prepolymer and an example of a photocurable coating composition for a lead-length steel sheet including a photocurable urethane (meth)acrylate resin are described. However, the following examples are only preferred examples of the present invention, and the present invention is not limited to the following examples.

[ Synthesis example ]

In a 5-liter round-bottom flask equipped with a stirrer, isophorone diisocyanate (1 mol), carbonate polyol, and reactive monomer ((Hydroxypropyl Acrylate:HPA, 2-Hydroxyethyl Acrylate: HEA, etc.) were added at the reaction molar ratio, and then heated to 80℃ for reaction. 50ppm of dibutyltindilaurylate was added, the reaction temperature was maintained at 70~80℃, and the reaction was carried out until the residual isocyanate concentration (NCO concentration) of the reactant reached the theoretical NCO concentration. After that, the reaction temperature is lowered to 60℃, and 0.25g of hydroquinone and 0.25g of phenocyanine are added as polymerization inhibitors, while maintaining the reaction temperature at 70~80℃ for 8~9 hours after the addition is completed with an infrared spectrometer. Complete the reaction by checking until the -NCO peak disappears completely with (FT-IR), add isobornyl acrylate so that the solid content is about 80%, mix sufficiently for 1 hour, and dilute at 25° C. 15,300 A urethane (meth)acrylate prepolymer having a weight average molecular weight of 1815 having a viscosity of cps was obtained.

[ Manufacturing Example 1 ]

50 parts by weight of the urethane (meth)acrylate prepolymer obtained by Synthesis Example, 25 parts by weight of isobornyl acrylate, 10 parts by weight of hexanediol diacrylate, 5 parts by weight of photoinitiator, 5 parts by weight of inorganic filler, 10 parts by weight of yellow pigment By mixing to prepare a photocurable coating composition for a lead-coated steel sheet comprising a photocurable urethane (meth)acrylate resin.

The liquid composition obtained in Preparation Example 1 was coated on a substrate in the following manner, and the properties thereof were measured by irradiating a single wavelength ray with mercury lighting alone and LED lighting, and then irradiating ultraviolet rays with mercury lighting. Preparation Example 1 is only an example of the present invention. It should be considered that LED lighting is possible in any type of illumination capable of irradiating single-wavelength rays, and mercury illumination is possible in any type of illumination capable of irradiating ultraviolet rays.

[ Manufacturing Example 2 ]

In order to increase the surface properties in the photocurable coating composition for a lead-coated steel sheet of Example 1, physical properties according to the type of inorganic filler were evaluated. 50 parts by weight of the urethane (meth)acrylate prepolymer obtained by Synthesis Example, 25 parts by weight of isobornyl acrylate, 10 parts by weight of hexanediol diacrylate, 5 parts by weight of photoinitiator, 5 parts by weight of inorganic filler, 10 parts by weight of yellow pigment By mixing to prepare a photocurable coating composition for a lead-coated steel sheet comprising a photocurable urethane (meth)acrylate resin.

The curing method, which was the best in Result Example 1, was first cured with LED lighting and then cured with mercury lighting in the second to compare physical properties. The experimental method was carried out in the same manner as in Preparation Example 1, and the curing method was cured with the first LED lighting and secondly mercury lighting, which is the best method in the result example 1, to prepare a specimen.

[ Manufacturing Example 3 ]

Alumina was applied as an inorganic filler in the photocurable coating composition for a lead-length steel sheet of Preparation Example 2, and the physical properties were evaluated by varying the content of alumina. 50 parts by weight of the urethane (meth)acrylate prepolymer obtained by Synthesis Example, 25 parts by weight of isobornyl acrylate, 10 parts by weight of hexanediol diacrylate, 5 parts by weight of photoinitiator, and 0, 3, 5, and 10 inorganic fillers, respectively By mixing parts by weight and 10 parts by weight of a colored pigment to prepare a photocurable coating composition for a lead-coated steel sheet comprising a photocurable urethane (meth)acrylate resin.

The curing method, which was the best in Result Example 1, was first cured with LED lighting and then cured with mercury lighting in the second to compare physical properties. The experimental method was carried out in the same manner as in Preparation Example 1, and the curing method was cured with the first LED lighting and secondly mercury lighting, which is the best method in the result example 1, to prepare a specimen.

[ Manufacturing Example 4 ]

In the photocurable coating composition for a lead-length steel sheet of Preparation Example 3, the appropriate amount of the inorganic filler was found. In the results derived in Preparation Example 3, the physical properties were evaluated by varying the content of the colored pigment. Depending on the content of the colored pigment, curing properties and thus surface properties may vary. 50 parts by weight of the urethane (meth)acrylate prepolymer obtained by Synthesis Example, 25 parts by weight of isobornyl acrylate, 10 parts by weight of hexanediol diacrylate, 5 parts by weight of photoinitiator, 5 parts by weight of inorganic filler, and 0 colored pigments , 5, 10, 15 parts by weight were mixed to prepare a photocurable coating composition for a lead-coated steel sheet comprising a photocurable urethane (meth)acrylate resin. The experimental method was carried out in the same manner as in Preparation Example 1, and the curing method was cured with the first LED lighting and the second mercury lighting, which are the best methods in the result example 1, to prepare a specimen.

[Test method]

① Specimen production

으로 조사하여 시편을 제조하였다. The prepared composition was coated with a bar coater #16 (application amount 15-20 microns) on a steel plate coated with a primer, and the irradiation intensity of mercury lighting and LED (405 nm: single wavelength light) was 90 mW/

A specimen was prepared by irradiation.

② Hardenability

Methyl Ethyl Ketone (MEK) is moistened on a cotton cloth and rubbed 50 cycles round and round, and there should be no abnormalities on the surface of the coated film.

③ Adhesiveness

A total of 100 specimens were made so that the width and length were 1 mm, and 3M scotch tape was attached and then removed, and the adhesion was evaluated by the number of remaining pieces.

④ Hardness measurement

It was measured with a pendulum hardness tester, and the hardness of the sample surface was measured through the number of reductions in the reciprocating vibration width of the pendulum. The higher the measured value, the higher the hardness.

⑤ CCET (Cross Cut Erichsen Test)

Fix the cross-cut test piece on the Ericsson tester and apply a load at a speed of 0.5mm every second. If a crack is seen on the coating film, stop the test and read the scale. There should be no cracks, peeling, or swelling of the coating film within 6.0mm of the progressed depth.

[ Result example 1 ]

The curability, adhesion, pendulum hardness, and CCET of the photocurable coating composition for a lead-coated steel sheet containing the photocurable urethane (meth)acrylate resin prepared according to Preparation Example 1 were measured by the above experimental method, and the results were then It is shown in Table 1.

division Mercury lighting LED alone UV->LED LED->UV Curability 10 times 40 times 50 times↑ 50 times↑ Adherence 10/100 100/100 90/100 100/100 Pendulum Hardness 56 105 118 128 CCET 4mm 6mm 6mm 7mm

As can be seen from the experimental results in Table 1, it was found that a remarkable difference in adhesion and hardenability was revealed depending on whether or not the LED lighting was applied. In the pendulum hardness measurement, it can be seen that when the LED (405 nm) illumination is first irradiated, the light penetrates into the coating film and a sufficient curing reaction proceeds, thereby increasing the hardness of the overall coating film. On the other hand, in the case of using a single UV light source, the surface hardening is excellent, but it is difficult to penetrate the light into the coating film, so that unreacted substances exist inside the coating film, and thus, the hardness of the coating film is greatly reduced.

LED lighting has no thermal deformation, can reduce the warm-up time, and does not generate ozone because ultra-high intensity single-wavelength ultraviolet rays are radiated. Therefore, in order to improve the curing failure that occurs when the aforementioned mercury lighting is used alone, and to realize the coating film with excellent adhesion and surface hardness, the inside of the coating film with colored pigments is cured using LED lighting that emits a single wavelength of ultra-high intensity. Afterwards, by curing the surface of the coating film using mercury lighting, it is possible to overcome curing obstacles and obtain physical properties such as excellent adhesion and surface hardness. Therefore, the method of curing with the primary LED lighting and then curing with the secondary mercury lighting is preferable in terms of physical properties.

[ Result example 2 ]

The curing properties, adhesion, pendulum hardness, and CCET of the photocurable coating composition for a lead-coated steel sheet containing the photocurable urethane (meth)acrylate resin prepared according to Preparation Example 2 were measured, and the results are shown in Table 2 below.

As a result of applying an inorganic filler to increase surface properties, physical properties such as hardenability, adhesion, and CCET were similar, and in the pendulum hardness test, which can determine the degree of surface hardness, alumina was more dominant than silica. This is because alumina, which has the second highest hardness after diamond, has a high self-hardness, so the above result was obtained, and it can be seen that the use of alumina preferably improves physical properties to improve the surface hardness.

[ Result Example 3 ]

The curability, adhesion, pendulum hardness, and CCET of the photocurable coating composition for a lead-coated steel sheet containing the photocurable urethane (meth)acrylate resin prepared according to Preparation Example 3 were measured, and the results are shown in Table 3 below.

Alumina (X) Alumina
(3 parts by weight) Alumina
(5 parts by weight) Alumina
(10 parts by weight) Curability 50 times↑ 50 times↑ 50 times↑ 45 times Adherence 100/100 100/100 100/100 100/100 Pendulum Hardness 121 124 132 115 CCET 7mm 7mm 7mm 6mm

If the alumina content is low, the physical properties such as hardenability, adhesion, and CCET are good, but it can be seen that the hardness is relatively weak, and if there are many, it can be seen that the overall physical properties are lowered. It can be seen that this is a result of the occurrence of hardening failure due to the application of an excessive amount of inorganic filler. As can be seen from the above results, it is preferable to use an alumina content of about 3 to 5 parts by weight.

[ Result Example 4 ]

The curing properties, adhesion, pendulum hardness, and CCET of the photocurable coating composition for a lead-coated steel sheet (PCM) containing the photocurable urethane (meth)acrylate resin prepared in Preparation Example 4 were measured, and the results are shown in Table 4 below. Shown in.

. Colored pigments
(X) Colored pigments
(5 parts by weight) Colored pigments
(10 parts by weight) Colored pigments
(15 parts by weight) Curability 50 times↑ 50 times↑ 50 times↑ 30 times Adherence 100/100 100/100 100/100 70/100 Pendulum
Hardness 127 127 133 95 CCET 7mm 7mm 7mm 5mm

As can be seen from the above results, it can be seen that when the content of the colored pigment is high (15 parts by weight), the overall physical properties including adhesion are deteriorated due to curing failure. When the content was small, most of the physical properties were satisfactory, but it was found that the hiding power was lowered below 5 parts by weight. Therefore, in the case of a colored pigment, it is preferable to use an amount of about 5 to 10 parts by weight.

< For lead-length steel plate Color using photo-curable coating composition Of lead sheet steel Manufacturing method>

In addition, another aspect of the present invention is (a) applying a photocurable coating composition for a lead-length steel plate on a steel plate substrate;

(b) Primary curing of the photocurable coating composition for the lead-length steel sheet by irradiating a single wavelength light beam to the photo-curable coating composition for the lead-length steel sheet with LED lighting while pressing the applied photocurable coating composition for the lead-length steel sheet using a pressing means. Step to do;

(c) secondary curing of the photo-curable coating composition for the lead-length steel sheet by irradiating ultraviolet light to the pre-cured photo-curable coating composition for the lead-length steel sheet.

The photocurable coating composition for the lead-length steel sheet in step (a) is the same as described above. Application may be selected from the group consisting of a roll coater, a bar coater, a spray coater, and a gravure coater.

In the step (b), the photocurable coating composition for a lead-length steel sheet may be cured in advance with a single wavelength light such as ultraviolet rays or visible light, and this may be performed at the same time or at the same time as pressing by a pressing means. The single wavelength may be selected according to physical properties to be implemented in the visible light region (within about 100 nm to 700 nm) in the ultraviolet region.

The effect of improving the physical properties of the colored lead-coated steel sheet prepared by the above manufacturing method using the above-described photo-curable coating composition for the lead-coated steel sheet is as described above.

As the colored lead-coated steel sheet manufactured by the manufacturing method undergoes a double curing process, it is possible to significantly reduce volatile organic compounds generated when using the existing heat-curable lead-coated steel sheet coating agent, and has excellent effects in improving workability and energy saving by photo-curing. have. In addition, it has an excellent effect in improving the adhesion problem caused by uncured by solving the curing failure that occurs when applying color to the existing UV paint.

In the manufacturing method, a single wavelength ray was irradiated with LED lighting in step (b) corresponding to the first curing, and ultraviolet rays were irradiated in step (c) corresponding to the second curing, but step (b) depending on the physical properties to be implemented. It should be taken into account that ultraviolet rays can be irradiated at and single wavelength rays can be irradiated with LED lighting in step (c).

In the above, preferred embodiments and applications of the present invention have been illustrated and described, but the present invention is not limited to the specific embodiments and application examples described above, and the present invention is not departing from the gist of the present invention claimed in the claims. Of course, modifications can be implemented by those of ordinary skill in the technical field to which they belong, and these modifications should not be individually understood from the technical spirit or prospect of the present invention, and the scope of the present invention is claimed to be described later. It should be understood as a range and its equivalent range.

Claims (5)

Urethane (meth)acrylate prepolymer, which is a copolymer of at least one diisocyanate compound and at least one hydroxyl group-containing (meth)acrylate;
(Meth)acrylate monomer;
Photoinitiators;
Inorganic fillers; And
Including; colored pigments;
The weight average molecular weight of the urethane (meth)acrylate prepolymer is 500 to 2000, the urethane (meth)acrylate prepolymer is 50 parts by weight, the (meth)acrylate monomer is 35 parts by weight, and the photoinitiator is 5 parts by weight Parts, and when the colored pigment is 10 parts by weight, the inorganic filler is 3 or 5 parts by weight, and the inorganic filler is alumina.
Photo-curable coating composition for lead-coated steel sheets. delete delete delete (a) applying a photocurable coating composition for a lead-length steel plate on a steel plate substrate;
(b) Primary curing of the photocurable coating composition for the lead-length steel sheet by irradiating a single wavelength light beam to the photo-curable coating composition for the lead-length steel sheet with LED lighting while pressing the applied photocurable coating composition for the lead-length steel sheet using a pressing means. The step of doing;
(c) secondary curing of the photocurable coating composition for the lead-length steel sheet by irradiating ultraviolet rays to the pre-cured photocurable coating composition for the lead-length steel sheet; and the photo-curable coating composition for the lead-length steel sheet according to claim 1 It is characterized in that it is a photo-curable coating composition for the lead-length steel sheet according to
Manufacturing method of colored lead sheet steel.