KR20190084778A - Coating composition - Google Patents

Abstract

The present invention relates to a coating composition comprising: a polyester-acrylic hybrid polyol resin; a curing agent; an acid catalyst; and a solvent, and having processability and high hardness.

Description

[0001] COATING COMPOSITION [0002]

The present invention relates to a clear coating composition for PCM (Pre-Coated Metal) which exhibits excellent workability and hardness and can exhibit excellent appearance characteristics and DOI (Distinctness of Image Gloss).

Background Art [0002] Recently, since the role of interior decoration for home appliances is becoming more important, there is an increasing demand for home appliances having various designs and brilliant colors. These home-use printing products are mainly coated with the PCM gravure offset method, and it is necessary to secure a high gloss level and high gloss. Accordingly, development of a coating material having basic physical properties, that is, processability and excellent hardness, to be possessed as PCM electronic appliances and having high linearity and scratch resistance has been developed.

In order to ensure excellent processability, a polyester resin having a number-average molecular weight of 1,000 to 10,000 was used for the clear-clear to be used in conventional printing products for home appliances. When such a polyester resin is used, it is possible to obtain a coating film excellent in workability, but there is a limitation in that the polyester resin alone can not exhibit excellent appearance and high ductility.

Korea Patent Publication No. 2011-0064816

The present invention provides a clear coating composition for PCM having excellent linearity, processability and high hardness.

The present invention provides a coating composition comprising a polyester-acrylic hybrid polyol resin, a curing agent, an acid catalyst and a solvent.

The present invention also provides a PCM steel sheet comprising a steel sheet and a coating film formed from the above-mentioned coating composition.

The coating composition of the present invention exhibits excellent processability and hardness, as well as excellent appearance and good spinning properties.

Hereinafter, the present invention will be described in detail. However, it should be understood that the present invention is not limited to the following embodiments, and various elements may be modified or selectively mixed according to need. Accordingly, it is to be understood that the invention includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

≪ Coating composition >

The coating composition according to the present invention comprises a polyester-acrylic hybrid polyol resin, a curing agent, an acid catalyst and a solvent. And may further include conventional additives in the PCM field as needed.

Hereinafter, the composition of the coating composition will be described in detail.

polyester -acryl hybrid  Polyol resin

In the coating composition according to the present invention, the polyester-acryl hybrid polyol resin is used as a main resin. As used herein, "polyol" or a modification thereof refers to a material having a hydroxyl value of at least two per molecule. Such a main resin reacts with a curing agent to form a coating film, gives a high gloss and high spinelity, and plays a role of securing the basic physical properties of the coating film, excellent processability, high hardness, chemical resistance, hardness and adhesion.

The polyester-acrylic hybrid polyol resin may have a number average molecular weight (Mn) of 1,500 to 5,500 g / mol, such as 2,000 to 4,500 g / mol. If the number average molecular weight is less than 1,500, the workability may deteriorate. If the number average molecular weight is more than 5,500, the appearance (linearity) may decrease. The polyester-acrylic hybrid polyol resin may have a hydroxyl value (OH value, based on solid content) of 20 to 70 mgKOH / g, such as 20 to 50 mgKOH / g. If the hydroxyl value is less than 20, the solvent resistance (MEK, methylethylkotone rubbing resistance) and chemical resistance may be deteriorated. If the hydroxyl value is more than 70, the processability may be deteriorated. The polyester-acrylic hybrid polyol resin may have an acid value (based on solids) of 5 to 30 mgKOH / g, such as 7 to 25 mgKOH / g. If the acid value is less than 5, the hardness, workability, and appearance (linearity) of the coating film may be lowered due to the lowering of the modifying ratio of acrylic and polyester. If the acid value is more than 30, yellowing of the coating film may occur due to unreacted double bonds. The polyester-acrylic hybrid polyol resin may have a glass transition temperature (Tg) of 20 to 50 캜, such as 25 to 45 캜. If the glass transition temperature is less than 20 캜, the hardness of the coating film may be lowered, and if it exceeds 50 캜, the workability may be deteriorated.

The polyester-acrylic hybrid polyol resin according to the present invention can be prepared as follows using at least one acid-based monomer containing a carboxylic acid functional group and at least one polyfunctional alcohol-based monomer, a metal catalyst, an acid anhydride and the like . However, the present invention is not limited to the following production method, and the steps of each process may be modified or selectively mixed if necessary.

The method for producing the polyester-acrylic hybrid polyol resin comprises polymerizing a mixture of at least one acid-based monomer containing a carboxylic acid functional group and at least one polyfunctional alcohol-based monomer, adding an acid anhydride having an unsaturated group thereinto, Ring-opening reaction at the main chain ends to prepare a polyester polyol prepolymer containing an unsaturated group and then polymerizing the polyester polyol prepolymer having an unsaturated group, an acrylic monomer and an ethylenically unsaturated monomer to obtain a polyester-acrylic hybrid polyol To produce a resin.

Hereinafter, the manufacturing method will be described separately for each step.

i) an unsaturated polyester Prepolymer  Produce

A mixture of at least one acid-based monomer containing a carboxylic acid functional group and at least one polyfunctional alcohol-based monomer is polymerized in the presence of a metal catalyst, and then an acid anhydride having an unsaturated group is introduced to perform ring-opening reaction at the end of the polyester main chain.

As the acidic monomer, there may be used any of conventional carboxylic acid and derivative compounds thereof having a carboxylic acid functional group, without limitation. For example, there may be mentioned a monofunctional or higher aromatic carboxylic acid, aliphatic carboxylic acid, alicyclic carboxylic acid, fatty acid, dimer acid, acid anhydride or a mixture thereof.

Non-limiting examples of the acidic monomers that can be used include isophthalic acid, terephthalic acid, dimethyl terephthalate, dimethyl isophthalate, trimellitic anhydride, adipic acid, azuraic acid, sebacic acid, succinic anhydride, Hydroxystearic acid, tallow hydrohalic acid, tallow hydrohalic acid, tallow hydrohalic acid, tallic anhydride, tallic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, Dimer fatty acid, hydrated dimeric acid, fumaric acid, maleic anhydride, and the like. The term " anionic surfactant " The above-described components may be used alone or in combination of two or more.

The acid monomers of the present invention may contain an alicyclic carboxylic acid having two or more functional groups and an aliphatic carboxylic acid. In one example, the acid monomers may be a mixture comprising 70 to 95 equivalent% of aliphatic carboxylic acid and 5 to 30 equivalent% of aliphatic carboxylic acid based on 100 equivalent% of total acid monomers.

When the bifunctional or higher alicyclic carboxylic acid is used in an amount less than 70 equivalent%, the naked eye lineity is lowered and the pencil hardness is lowered. When the amount is more than 95 equivalent%, the workability may be deteriorated. If the amount of the aliphatic carboxylic acid exceeds 30 equivalent%, the glass transition temperature of the coating film may be lowered and the pencil hardness may be seriously deteriorated. If the amount is less than 5 equivalent%, the workability may be lowered.

As the polyfunctional alcohol-based monomer, alcohols and derivatives thereof of the present invention containing an alcohol functional group having two or more functionalities may be used without limitation. Examples include aliphatic alcohols, alicyclic alcohols, aromatic alcohols, or mixtures thereof.

Examples of usable polyfunctional alcohol-based monomers include alcohols having 2 to 16 carbon atoms, and non-limiting examples thereof include ethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,3-butylene glycol, Butanediol, 1,5-pentanediol, 1,6-hexanediol, 2-butyl-2-ethyl-1,3-propanediol, cyclohexanedimethanol, diethylene glycol, glycerin, , 3-propanediol, neopentyl glycol, pentaerythritol, tris-hydroxyethyl isocyanurate, trimethylolethane, trimethylol propane, ditrimethylol propane and the like. The above-described components may be used alone or in combination of two or more.

The polyfunctional alcohol-based monomer of the present invention may include bifunctional aliphatic alcohols, alicyclic alcohols, and trifunctional or more polyfunctional alcohols. At this time, as the trifunctional or more polyfunctional alcohol monomer, an alcohol having three or more functionalities commonly known in the art can be used without limitation. Non-limiting examples of trifunctional or higher alcohol monomers that can be used include trimethylolpropane, pentaerythritol, triethylolpropane, and the like.

For example, the polyfunctional alcohol-based monomer may contain 40 to 80 equivalent% of bifunctional aliphatic alcohol, 20 to 60 equivalent% of alicyclic alcohol, and 0 to 5 equivalent of trifunctional or more polyfunctional alcohol, based on 100 equivalent% of the total alcohol- %. ≪ / RTI >

If the bifunctional aliphatic alcohol monomer is used in an amount less than 40 equivalent%, the processability of the coated film to which the polyester-acrylic hybrid polyol resin is applied may be poor, and if it exceeds 80 equivalent%, the pencil hardness may be weak. If the amount of the alicyclic alcohol monomer is less than 20 equivalent weight, the pencil hardness may be weak. When the amount of the alicyclic alcohol monomer exceeds 60 equivalent weight, the workability may be weak. In addition, when the amount of the alcohol monomer having three or more functional groups is more than 5 equivalent%, the processability is lowered, and when the unsaturated group is added, the uniformity may be lowered.

For example, a mixture of the acid monomer and the polyfunctional alcohol-based monomer and the reaction catalyst are introduced into a reactor equipped with a stirrer, a thermometer, a filling column, an H-type separator, a condenser and a nitrogen inlet tube, (For example, xylene) is added to the mixture while the condensation water is removed to 250 DEG C and the acid value falls within a specific range (e.g., 15 to 30 mgKOH / g), followed by azeotropic distillation at 210 to 250 DEG C, (For example, 5 or less), the mixture is cooled to 150 DEG C or lower, and then acid anhydride containing an unsaturated group is added thereto to carry out the ring-opening reaction.

As the reaction catalyst, a conventional metal catalyst used in the production of polyester polyol resin may be used, and for example, it may be a tin catalyst. Such a metal catalyst may be used in the range of 0.01 to 0.1% by weight based on the total weight of the solid content of the polyester polyol prepolymer.

As the acid anhydrides, conventionally known acid anhydrides, which contain at least one unsaturated group in the molecule, such as an ethylenic unsaturated group, can be used without limitation. For example, at least one of maleic anhydride represented by the following formula (1) and tetrahydrophthalic anhydride represented by the following formula (2) may be used.

The carboxylic acid functional group-containing acid monomer and the polyfunctional alcohol monomer may be adjusted so that the equivalence ratio of alcohol / carboxylic acid is 1.05 to 1.50.

The acid anhydride may be used in a range of 10 to 110 mol% based on the number of moles of the produced polyesters. If the amount of the acid anhydride is less than 10 mol%, the amount of the unsaturated group is relatively small and the amount of the polyester prepolymer which does not participate in the reaction after the production of the polyester-acrylic hybrid polyol resin is increased, whereby the pencil hardness of the coating film may be decreased. On the other hand, when the amount of the acid anhydride is more than 110 mol%, the processability is lowered and the gel can be formed in the production of the polyester-acrylic hybrid polyol resin.

By the ring-opening reaction with an acid anhydride having an unsaturated group as described above, a polyester polyol prepolymer having an unsaturated group is produced. The polyester polyol prepolymer having an unsaturated group has a number average molecular weight (Mn) of 500 to 3,000 g / mol, an OH value of 25 to 120 mgKOH / g on a solid basis, an acid value of 10 to 50 mgKOH / g , And a glass transition temperature (Tg) of -10 to 50 캜. If the number average molecular weight is less than 500, the workability may deteriorate. If the number average molecular weight is less than 40,000 KOH / g, the appearance (linearity) may be lowered. If the number average molecular weight is less than 500, / g, the workability may be deteriorated. When the acid value is less than 10 mgKOH / g, the acrylic-polyester modification ratio is lowered, and the appearance, workability, and hardness are all lowered. When the acid value is more than 50 mgKOH / g, yellowing of the final transparent coating film may occur due to unreacted unsaturated groups. If the glass transition temperature of the polyester polyol prepolymer is less than -10 ° C, the hardness may be lowered. If the glass transition temperature is higher than 50 ° C, the workability may be deteriorated.

ii) polyester -acryl hybrid  Preparation of polyol resin

A polyester-acryl hybrid polyol resin is prepared by polymerizing a mixture of an unsaturated polyester polyol prepolymer, an acrylic monomer and an ethylenically unsaturated monomer prepared in the above reaction. In the polymerization reaction, a radical polymerization initiator and an organic solvent may be used.

As the acrylic monomer, any of the acrylic monomers known in the art may be used without limitation. For example, the acrylic monomer may include at least one of a non-functional acrylic monomer and a hydroxyl group-containing acrylic monomer.

The non-functional acrylic monomer is not particularly limited so long as it does not adversely affect the formation of the acrylic polyol resin. Non-limiting examples of usable non-functional acrylic monomers can be one or more selected from the group consisting of alkyl (meth) acrylates, cycloalkyl (meth) acrylates, bicycloalkyl (meth) acrylates. For example, methyl methacrylate, ethyl methacrylate, isobutyl methacrylate, n-butyl methacrylate, tertiary butyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, isobornyl methacrylate Acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, isobutyl acrylate, n-butyl acrylate, tertiary butyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, isobornyl Acrylate, cyclohexyl acrylate, or mixtures thereof.

Non-limiting examples of the hydroxyl group-containing acrylic monomer include 2-hydroxyethyl methacrylate, hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxyethyl acrylate, 2- Acrylate, urethane acrylate, urethane acrylate, urethane acrylate, urethane acrylate, urethane acrylate, urethane acrylate, urethane acrylate, urethane acrylate, (Meth) acrylic acid) such as 4-hydroxymethylcyclohexyl-methyl acrylate, 4-hydroxymethylcyclo-methyl methacrylate, monocarboxylic acid (for example, Ethylenic unsaturation derived from the reaction of epoxy compounds (e.g., glycidyl ethers and esters) that are not involved in radical polymerization Ta-like-hydroxy ester functional monomers can be used.

As the ethylenically unsaturated monomer, an unsaturated monomer known in the art can be used without limitation. Examples include styrene and derivatives thereof, butadiene, acrylic or methacrylic acid esters of alkyl of 1 to 12 carbon atoms, mixtures thereof, and the like.

The use ratio of the mixture of the unsaturated group-containing polyester prepolymer and the acrylic monomer and the ethylenically unsaturated monomer may be 20:80 to 80:20 by weight, for example, 30:70 to 70:30 by weight. When the content of the mixture of the acrylic monomer and the ethylenically unsaturated monomer is less than 20% by weight, the hardness and ductility may be deteriorated, and if it exceeds 80% by weight, the workability may be deteriorated.

As the polymerization initiator, an ordinary initiator known in the art can be used without any limitation. Nonlimiting examples of initiators that can be used are 2,2'-azobis (2-methylbutylonitrile), 2,2'-azobisisobutyronitrile, dibenzoyl peroxide, tertiary butyl peroxybenzoate Ethylhexanoate, tertiary butyl peroxide, tertiary butyl peroxy-2-ethyl hexanoate, tertiary butyl peroxyacetate, tertiary amyl peroxy-2-ethyl hexanoate, Oxides, dicumyl peroxides, or mixtures thereof. The content of the initiator may be from 0.5 to 10% by weight, based on the total weight of the reaction mixture for preparing the polyester-acrylic hybrid polyol resin. When the content of the initiator falls within the above-mentioned range, the molecular weight of the resin can be prevented from lowering and the coating composition can be prevented from being uncured.

The solvent is not particularly limited so long as it does not adversely affect the polymerization reaction of the acrylic polyol resin, and a solvent known in the art can be used. Non-limiting examples of usable solvents include aromatic hydrocarbon solvents such as toluene, xylene, cocosol # 100, # 150; Ketone solvents such as methyl ethyl ketone, methyl propyl ketone, methyl butyl ketone and ethyl propyl ketone; Ester solvents such as methyl acetate, ethyl acetate, n-propyl acetate, n-butyl acetate, ethyl ethoxypropionate and the like; alcohol solvents such as n-butanol, propanol and 1-methoxy-2-propanol. The above-mentioned components may be used alone or in combination of two or more.

For example, the polyester prepolymer having an unsaturated group is mixed with a solvent, the temperature is raised to a predetermined temperature (for example, 145 ° C) while an inert gas is injected into the reactor, and the mixture is maintained for a predetermined time. And then the acrylic polymerization reaction is carried out to obtain a polyester-acrylic hybrid polyol resin. Such a polyester-acrylic hybrid polyol resin can exhibit high linearity, hardness and excellent processability.

The polyester-acrylic hybrid polyol resin has a number average molecular weight (Mn) of 1,500 to 5,500 g / mol, an OH value of 20 to 70 mgKOH / g on a solid basis, an acid value of 5 to 30 mgKOH / g , And a glass transition temperature (Tg) of 20 to 50 캜.

In the coating composition according to the present invention, the content of the polyester-acrylic hybrid polyol resin may be 50 to 75% by weight based on the total weight (100% by weight) of the coating composition. If the content of the polyester-acrylic hybrid polyol resin is less than 50% by weight, the corrosion resistance, workability and curability are lowered. If the content is more than 75% by weight, appearance and workability may be deteriorated. The content of the polyester-acryl hybrid polyol resin may be 35 to 50% by weight based on the total weight of the solid content.

Hardener

In the coating composition according to the present invention, the curing agent serves to cure the polyester-acrylic hybrid polyol resin to form a stable coating film.

As the curing agent, those generally used for a resin having a hydroxyl group can be used without limitation. For example, a melamine resin or the like can be used. The melamine resin is obtained by polymerization of alcohol and formaldehyde. For example, polymerization of methanol and formaldehyde in methoxy melamine resin and mixing of methanol and iso-butanol or normal-butanol in methoxy / butoxy mixed melamine resin Can be obtained by polymerization of formaldehyde. Non-limiting examples of melamine resins that can be used in the present invention include hexamethylol melamine, hexamethoxymethyl melamine, hexabutoxymethyl melamine, and mixtures thereof. The molecular weight of the melamine resin may range from 300 to 1,000.

The content of the curing agent may be 5 to 15% by weight based on the total weight (100% by weight) of the coating composition. If the content of the curing agent is less than 5% by weight, the hardness, hardenability, solvent resistance, stain resistance, chemical resistance, weather resistance and the like of the coating film may be deteriorated, and if it exceeds 15% by weight, the flexibility, impact resistance and acid resistance Can be degraded.

Acid catalyst

In the coating composition according to the present invention, the acid catalyst serves as a curing accelerator for improving the denseness of the coating film by promoting curing between the polyester-acrylic hybrid polyol resin and the curing agent (melamine resin).

Examples of the acid catalyst that can be used include sulfonic acid compounds, and non-limiting examples thereof include para-toluene sulfonic acid (p-TSA), dinonylnaphthalene sulfonic acid (DNNSA) Dinonylnaphthalene disulfonic acid, and dodecylbenzene sulfonic acid (DDBSA). These may be used alone or in combination of two or more.

The content of the acid catalyst may be 0.1 to 3% by weight based on the total weight (100% by weight) of the coating composition. If the content of the acid catalyst is less than 0.1% by weight, the coating material may be uncured to lower the hardness, chemical resistance, curability and weatherability. If the content of the acid catalyst exceeds 3% by weight, Deterioration of appearance and the like may occur.

solvent

The coating composition according to the present invention can be used as a solvent without limitation, conventional organic solvents known in the art. Examples of the organic solvent include aromatic hydrocarbon solvents, ester solvents, ether solvents, alcohol solvents, and mixtures thereof.

Examples of usable organic solvents include, but are not limited to, Cocosol # 100 (Kocosol # 100, K-100, SK Energy Co.), Cocosol # 150 (Kocosol # 150, K-150, SK Energy Co.) Propylene glycol methyl ether acetate, n-butyl acetate, propylene glycol monomethyl acetate, 3-methoxybutyl acetate, ethylene glycol butyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether acetate, Glycol methyl ether, diethylene glycol ethyl ether, diethylene glycol butyl ether, ethanol, isopropanol, n-butanol, amyl alcohol or mixed solvents thereof.

The content of the organic solvent may be a residual amount satisfying the total weight (100% by weight) of the coating composition, for example, 30 to 50% by weight based on the total weight of the coating composition. When the solvent falls within the above-mentioned range, the workability is improved and the excellent physical properties of the coating film can be exerted.

additive

The coating composition according to the present invention may further include conventional additives used in the field of PCM coating composition to the extent that the effect of the invention is not impaired.

Nonlimiting examples of usable additives include, but are not limited to, dispersants, leveling agents, adhesion improvers, curing retardants, surface modifiers, defoamers, surfactants, softeners, thickeners, weathering additives, desiccants, external modifiers, absorbents, quenchers, Or a mixture of two or more thereof. The above-mentioned additives may be added in an amount known in the art, and the content thereof is not particularly limited. In one example, the content of each of the gauzes may be from 0.1 to 10% by weight, for example from 0.5 to 5% by weight, based on the total weight of the coating composition (100% by weight).

The dispersing agent serves to disperse each material constituting the coating composition and prevent the re-agglomeration through maintaining the distance, thereby exhibiting uniform physical properties of the coating film. As the dispersing agent, those conventionally known in the art can be used, and for example, a dispersant of a high molecular weight block copolymer type and the like are available.

The leveling agent is intended to improve the appearance property of the coating film while improving the adhesion in the composition by leveling the coating composition so as to be flat and smoothly coated. The leveling agent may be any of those known in the art without limitation. Examples of the leveling agent include an acrylic type, a silicone type, a polyester type, and an amine type leveling agent.

The adhesion improving agent is added to improve the adhesion of the coating film to the substrate. Examples of usable adhesion improvers include silane adhesion improvers, polyester adhesion improvers, and mixtures thereof.

The antifoaming agent is a mixture of a hydrophilic and a polysiloxane. It serves to increase the appearance of the coating film by suppressing bubbles generated during coating. As the antifoaming agent, conventional antifoaming agents known in the art can be used without limitation. As an example, a defoamer of polysiloxane type may be used.

A quencher is added to scatter light on the surface of the coating to reduce gloss. Non-limiting examples of usable quenchers include synthetic silica quenchers, polypropylene quenchers, polyethylene quenchers, or mixtures thereof. By adjusting the quenching agent to have a predetermined particle size, the surface area of the undercoat may be increased to improve the adhesion with the topcoat.

The curing retarder can be used to control the hardening speed of the coating film surface to improve the smoothness of the cured coating film and to suppress the peeling phenomenon. Examples thereof include triethylamine and dimethylethanolamine.

The coating composition of the present invention can be produced by a conventional method known in the art. For example, the coating composition of the present invention can be produced by mixing a polyester-acrylic hybrid polyol resin, a curing agent, a curing catalyst, .

<PCM steel plate>

The present invention provides a PCM steel sheet having a coated film formed using the above-described coating composition.

Wherein the PCM steel sheet comprises a steel sheet and at least one coating layer formed on the surface of the steel sheet, wherein at least one of the one or more coating layers is a coating film formed from the coating composition comprising the polyester- For example, a PCM clear coating film). Such a PCM clear coating film can secure high hardness, high linearity and excellent processability at the same time.

The one or more coat layers include a coat (e.g., a clear coat) formed from the coating composition of the present invention, and may further optionally include a undercoat layer and / or a top coat layer. The undercoating layer and the topcoating layer may be applied to any conventional undercoat or topcoat in the art without limitation.

As the steel sheet, there can be used any of metal plates used for building interior and exterior materials in the field. For example, cold rolled steel (CR), zinc hot dip steel (GI), electro-zinc steel (EGI) Galvanized galvanized steel sheets, molten aluminum-zinc alloyed galvanized steel sheets, aluminum sheets, etc. are used for the galvanized steel sheets, galvanized steel plates, galvanized steel sheets, galvanized steel sheets, have.

The thickness of the coating layer formed on the metal plate is not particularly limited. For example, the thickness of the dried coating film may be 3 to 30 탆.

The PCM steel sheet according to the present invention can be manufactured according to a conventional method in the art. For example, the PCM steel sheet may be formed by coating the above-mentioned coating composition on a metal plate as a substrate and then drying. As a coating method, a conventional coating method known in the art can be applied. For example, a curtain coating, a roll coating, an immersion coating, a bar coating, and a spray coating can be applied.

The firing conditions can be appropriately changed according to the width and thickness of the bake plate, and the atmospheric conditions baked according to the line speed. For example, the firing conditions can be performed for 30 to 40 seconds under the condition that the peak metal temperature (PMT) .

The PCM steel sheet prepared as described above can be pretreated with chromate, phosphate or the like before coating. The PCM steel sheet of the present invention can be usefully used for household electrical products, and is also applicable to interior and exterior materials for buildings. However, the present invention is not limited thereto.

Hereinafter, the present invention will be described more specifically by way of examples. However, the following examples are provided to aid understanding of the present invention and are not intended to limit the scope of the present invention in any sense.

[Synthesis Example 1: Production of polyester-acrylic hybrid polyol (A) resin]

1-1. Unsaturated group content polyester Prepolymer  Produce

A synthetic four-necked flask equipped with a thermometer, a stirrer, a filling column, a H separator, a condenser and a heating device was charged with 130 g of neopentyl glycol, 180 g of 1,4-cyclohexanedimethanol, 335 g of hexahydrophthalic anhydride, 4101 (manufactured by pmc organometallix), and the reaction was carried out by raising the temperature to 240 ° C while removing the condensed water in an inert gas atmosphere. 24 g of xylene was added by cooling at an acid value of 25, and azeotropic distillation was carried out at 230 ° C. When the acid value became 4, the reaction mixture was cooled, and 35 g of maleic anhydride was introduced at 160 ° C or lower. When the acid value became 30 to 40, the mixture was cooled and diluted with 68 g of cocosol, 27 g of cocosol and 27 g of a cyclohexanone, An unsaturated group-containing polyester prepolymer having an acid value of 35 mgKOH / g and a glass transition temperature (Tg) of 19 占 폚 was obtained.

1-2. polyester -acryl hybrid  Manufacture of polyol resin

The acrylic polymerization reaction was carried out using the unsaturated group-containing polyester prepolymer. 377 g of the unsaturated group-containing polyester prepolymer prepared in the above 1-1 and 145 g of cocosol 100 were introduced into a synthetic four-necked flask equipped with a thermometer, a stirrer, a condenser and a heating device and uniformly mixed. And the temperature was maintained. 90 g of styrene monomer, 13 g of 2-hydroxyethyl acrylate, 56 g of n-butyl methacrylate, 6 g of ethylhexyl methacrylate, 17 g of isobornyl acrylate and 10 g of cyclohexyl methacrylate were uniformly mixed, 3-oxy-2-ethylhexanoate, and 29 g of cocosol 100 were homogeneously mixed and homogeneously separated for 240 minutes, and kept isothermal for 120 minutes. After the completion of the maintenance, the reaction product was cooled while diluting with 45 g of butyl acetate to obtain a solid material having a solid content of 60%, a Gardner viscosity Z, a hydroxyl value of 30 mgKOH / g based on the solid weight basis, an acid value of 20 mgKOH / g and a number average molecular weight (Mn) g, a weight-average molecular weight (Mw) of 8,000 g / mol and a glass transition temperature (Tg) of 35 캜.

[Synthesis Example 2: Preparation of polyester-acrylhybrid polyol (B) resin]

2-1. Unsaturated group content polyester Prepolymer  Produce

A synthetic four-necked flask equipped with a thermometer, a stirrer, a filling column, a H separator, a condenser and a heating device was charged with 167 g of neopentyl glycol, 232 g of 1,4-cyclohexanedimethanol, 430 g of hexahydrophthalic anhydride, 4101 (manufactured by pmc organometallix), and the reaction was carried out by raising the temperature to 240 캜 while removing the condensed water in an inert gas atmosphere. 31 g of xylene was added by cooling at an acid value of 25 and the mixture was subjected to azeotropic distillation at 230 ° C. After the acid value was reduced to 4, 21 g of maleic anhydride was added at 160 ° C. or lower to maintain the reaction at 160 ° C., When the acid value became 15, the mixture was cooled to be diluted with 84 g of cocosol 100, 34 g of cocosol 150 and 51 g of cyclohexanone to obtain a polyurethane resin having a number average molecular weight (Mn) of 2,000 g / mol, a solid content of 80%, a hydroxyl value based on a solid content of 44 mgKOH / g, mgKOH / g and a glass transition temperature (Tg) of 17 deg. C were obtained.

2-2. polyester -acryl hybrid  Manufacture of polyol resin

The acrylic polymerization reaction was carried out using the unsaturated group-containing polyester prepolymer. 377 g of the unsaturated group-containing polyester prepolymer prepared in 2-1 and 145 g of cocosol 100 were introduced into a four-necked flask for synthesis, equipped with a thermometer, a stirrer, a condenser and a heating device, and uniformly mixed. And the temperature was maintained. 90 g of styrene monomer, 13 g of 2-hydroxyethyl acrylate, 56 g of n-butyl methacrylate, 6 g of ethylhexyl methacrylate, 17 g of isobornyl acrylate and 10 g of cyclohexyl methacrylate were uniformly mixed, 3-oxy-2-ethylhexanoate, and 29 g of cocosol 100 were homogeneously mixed and homogeneously separated for 240 minutes, and kept isothermal for 120 minutes. After the completion of the maintenance, the reaction product was cooled while being diluted with 45 g of butyl acetate to obtain a solid content of 60%, a Gardner viscosity of Z-, a hydroxyl value of 40 mgKOH / g based on the solid weight, an acid value of 10 mgKOH / g and a number average molecular weight (Mn) of 3,200 mols / g, a weight-average molecular weight (Mw) of 8,000 g / mol, and a glass transition temperature (Tg) of 32 DEG C.

[Synthesis Example 3: Production of polyester polyol (C) resin]

A synthetic four-necked flask equipped with a thermometer, a stirrer, a charging column, a H separator, a condenser and a heating device was charged with 98 g of neopentyl glycol, 56 g of trimethylolpropane, 39 g of ethylene glycol, 135 g of 1,4-cyclohexanedimethanol, 116 g of talic anhydride, 114 g of adipic acid, 43 g of terephthalic acid, 130 g of isophthalic acid and 0.3 g of Fascat 4101 (pmc organometallix) were charged and the temperature was raised to 220 캜 while removing the condensed water in an inert gas atmosphere. The mixture was cooled at an acid value of 15 to 20, and 32 g of xylene was added thereto. The mixture was subjected to azeotropic distillation at 210 ° C and cooled when the acid value became 5 or less. The mixture was diluted with 317 g of cocosol 100 (SK chem) to obtain a solid content of 65% , An acid value of 3.7 mgKOH / g, a hydroxyl value of 90 mgKOH / g on a solid weight basis, and a weight average molecular weight (Mw) of 2,000 g / mol.

[Synthesis Example 4: Production of urethane-modified polyester-acrylic hybrid resin (D)] [

4-1. polyester Prepolymer  Produce

A synthetic four-necked flask equipped with a thermometer, stirrer, filling column, H separator, condenser and heating equipment was charged with 137 g of neopentyl glycol, 190 g of cyclohexanedimethanol, 354 g of hexahydrophthalic anhydride, 354 g of Fascat 4101 Ltd.), and the reaction was carried out by raising the temperature to 240 캜 while removing the condensed water in an inert gas atmosphere. 24 g of xylene was added by cooling at an acid value of 25 and azeotropic distillation was carried out at 230 ° C. When the acid value became 5 or less, 67 g of Cocosol 100 (SK chem), 27 g of Cocosol 150 (SK chem) And a polyphenylene prepolymer having a number average molecular weight (Mn) of 1,950 g / mol, a solid content of 80%, an acid value of 3.8 mgKOH / g and a glass transition temperature (Tg) of 16 캜 was obtained.

4-2. acryl Prepolymer  Produce

140 g of synthetic quaternary cocosol # 100 having a thermometer, a stirrer, a condenser and a heating device was charged, uniformly mixed, and heated to an isothermal temperature (145 ° C) under nitrogen injection. After the isothermal holding was stabilized, 196 g of methyl methacrylate, 42 g of 2-hydroxyethyl acrylate, 70 g of n-butyl acrylate and 252 g of isobornyl acrylate were uniformly mixed and 14 g of ditertiary butyl peroxide and 67 g of cocosol 100 Homogeneously mixed, homogenously separated for 240 minutes, and kept isothermal for 120 minutes. After the completion of the maintenance, the reaction product was cooled while being diluted with 13 g of butyl acetate to obtain a product having a solid content of 70%, a hydroxyl value of 32 mgKOH / g on a solid weight basis, a Gardner viscosity Y, a number average molecular weight (Mn) of 2,400 g / Mw) of 4,800 g / mol and a glass transition temperature (Tg) of 30 占 폚.

4-3. Urethane modification polyester -acryl hybrid  Manufacture of resin

151 g of the polyester prepolymer obtained in the above step 4-1 and 402 g of the acrylic prepolymer obtained in the above step 4-2 were introduced into a synthetic four-necked flask equipped with a thermometer, a stirring device, a filling column, a H separation pipe, a condenser and a heating device, After the mixture was heated to 50 ° C, 17.8 g of hexamethylene diisocyanate was added thereto, and the temperature was raised to 60 ° C. in an inert gas atmosphere to carry out the holding reaction. The residual NCO% was measured and found to be 65% by solid content, 30 mgKOH / g based on solid content, 30% / mol, a weight average molecular weight (Mw) of 35,000 g / mol, and a glass transition temperature (Tg) of 20 DEG C.

[Synthesis Example 5: Production of polyester-acrylic blend polyol (E)] [

153 g of the polyester prepolymer prepared in Synthesis Example 4-1, 175 g of the acrylic prepolymer prepared in Synthesis Example 4-2, and 22 g of Cocosol 100 were uniformly mixed in a flask equipped with a stirrer to give a number average molecular weight (Mn) Acrylic blend polyol resin having a glass transition temperature (Tg) of 3,400 g / mol, a solid content of 70%, a hydroxyl value of 60 mgKOH / g on a solid weight basis, and a glass transition temperature (Tg) of 23 ° C.

[ Example  1-2]

The coating composition of Example 1-2 was prepared according to the composition shown in Table 1 below.

[ Comparative Example  1-3]

A coating composition of Comparative Example 1-3 was prepared according to the composition of Table 1 above.

[ Experimental Example . Property evaluation]

Physical properties of the clear coating compositions for PCM prepared in Example 1-2 and Comparative Examples 1-3 were evaluated as follows.

(KCC, FP1817) and a top coat (KCC, FJ2604) were coated on a GI (Galvanized Iron) material to a thickness of 5 占 퐉 and 20 占 퐉, respectively, -3 was coated with a thickness of 20 탆 to prepare a specimen. The properties of the specimens were measured by the following methods, and the results are shown in Table 2.

(1) Pencil Hardness

Using Mitsubishi Uni Pencil (3B, 2B, B, HB, F, H, 2H and 3H), the hardness of each pencil was measured.

(2) T bending

According to ASTM D4145, the specimen was bended to evaluate the crack level of the film at the bending portion and the peel-off of the film after taping.

(3) glossy

A 60 degree gloss was measured using a BYK gloss meter.

(4) Hardening degree

After sufficiently wetting the gauze with MEK (methylethylkotone) solution, the specimen was rubbed with a predetermined number of times 10 cm in length at a rate of 100 round trips per minute under a load of about 1 to 1.5 kg, .

(5) Appearance (Sun spirituality)

CF (combined factor) values were measured using BYK WAVESCAN. The higher the CF value, the better the linearity.

(6) yellowing

After coating the clear coating film on the white coating film, the clear coating film was visually checked for yellowing.

As shown in Table 2, the paints of Examples 1 and 2 containing the polyester-acrylic hybrid polyol resins (A) and (B) according to the present invention had gloss, workability, hardness, appearance, And it was confirmed that both of them showed excellent physical properties. On the other hand, the paint of Comparative Example 1-3 containing no polyester-acrylic hybrid polyol resin showed poor physical properties such as workability, hardness and gloss.

From the above results, it was found that the coating composition comprising the polyester-acrylic hybrid polyol resin of the present invention exhibits high appearance (linearity) and hardness and satisfies high porosity.

Claims (8)

A polyester-acrylic hybrid polyol resin, a curing agent, an acid catalyst and a solvent. The polyurethane resin composition according to claim 1, wherein the polyester-acrylic hybrid polyol resin has a number average molecular weight (Mn) of 1,500 to 5,500 g / mol, an OH value of 20 to 70 mgKOH / g on a solid basis, To 30 mgKOH / g, and a glass transition temperature (Tg) of from 20 to 50 占 폚. The polyurethane resin composition according to claim 1, wherein the polyester-acrylic hybrid polyol resin
(OH) of 25 to 120 mgKOH / g, an acid value of 10 to 50 mgKOH / g and a glass transition temperature (Tg) of from 500 to 3,000 g / mol, Unsaturated group-containing polyester prepolymer at 10 to 50 ° C,
Acrylic monomers and
The ethylenically unsaturated monomer
By weight of a polymerization initiator. The polyurethane prepolymer as claimed in claim 3, wherein the unsaturated group-containing polyester prepolymer is a polycondensate of a mixture comprising at least one acid-based monomer containing a carboxylic acid functional group, at least one polyfunctional alcohol-based monomer and an acid anhydride having an unsaturated group Composition. The coating composition according to claim 3, wherein the ratio of the unsaturated group-containing polyester prepolymer to the mixture of the acrylic monomer and the ethylenically unsaturated monomer is 20: 80 to 80:20 by weight. 5. The coating composition according to claim 4, wherein an equivalent ratio of the alcohol / carboxylic acid is in the range of 1.05 to 1.50 in the ratio of the acid-based monomer containing the carboxylic acid functional group and the polyfunctional alcohol-based monomer. The coating composition according to claim 4, wherein the content of the acid anhydride ranges from 10 to 110 mol% based on the number of moles of the polyester in the unsaturated group-containing polyester prepolymer. The coating composition according to claim 1, wherein the coating composition comprises 50 to 75% by weight of a polyester-acryl hybrid polyol resin, 5 to 15% by weight of a curing agent, 0.1 to 3% by weight of an acid catalyst and 100% by weight of the composition.