KR101958984B1 - Over coating compositions for pre-coated metal color steel sheet and painted steel sheet using the same - Google Patents

Abstract

The present invention relates to a coating composition for phase inversion of PCM multicolor steel sheet and a coated steel sheet using the same, and more particularly, to a coating composition for PCM multicolor steel sheet which is produced by a condensation reaction of a polyhydric alcohol and a dicarboxylic acid, % Of a thermosetting polyester resin and a PCM multicolored steel sheet coated on at least one side of the above phase change coating composition.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating composition for an upper phase of a PCM multicolor steel sheet, and a coated steel sheet using the same. BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

The present invention relates to a coating composition for phase inversion of PCM multicolor steel sheet and a coated steel sheet using the same, and more particularly to a coating composition for phase inks on a multi-color steel sheet having improved physical properties and a coated steel sheet using the same .

In general, the paint applied to the PCM (Pre-Coated Metal) steel sheet is subjected to a post-coating process, and thus post-processability is required. In addition, since the product is exposed to various scratch factors in the living environment after the manufacture of the product, it must have high hardness in order to protect the appearance and maintain appearance.

However, in general, since the hardness and workability are opposite to each other, the physical properties of the other are deteriorated in order to improve the properties of either one. Therefore, it is very difficult to construct a curing system by synthesizing a resin that simultaneously satisfies hardness and workability. In order to prepare a coating composition which satisfies both hardness and workability, a polyester resin having a very high molecular weight and a high glass transition temperature is suitable as the binder resin.

In the case of coated steel sheets for pre-coated metal (PCM), coating and baking of two primer and top two baking systems or primer, ) And a Clear 3 Coating 3 Baking system.

Conventional pre-coated metal (PCM) paints are mostly made of Hadouwa Sangdo 2 Coating 2 Baking system, which is based on the optimum condition of the physical properties such as the workability and appearance of the coating film to be. This is known as an optimal coating system that can represent optimal physical property conditions that can meet consumer's demands.

On the other hand, in order to apply a wet on wet system in which a coating composition for a top is coated on a non-dried primer coating composition, a resin having excellent flexibility and adhesion is applied, And the like have been demanded to be developed.

Japanese Patent Application Laid-Open No. 10-2006-0072482 (Jun. 28, 2006)

Accordingly, one aspect of the present invention is to provide a coating composition for phase inversion of PCM multicolor steel sheet having excellent physical properties and being usable on a multicolored steel sheet of various colors.

Another aspect of the present invention is to provide a PCM multicolored steel sheet painted with the paint composition for topical use of the present invention.

According to one aspect of the present invention, there is provided an image-forming coating composition comprising a thermosetting polyester resin produced by a condensation reaction of a polyhydric alcohol and a dicarboxylic acid and containing the polyhydric alcohol-derived moiety in an amount of 25 to 40 wt% / RTI >

According to another aspect of the present invention, there is provided an undercoat paint composition comprising a thermosetting polyester resin produced by condensation reaction of a polyhydric alcohol and a dicarboxylic acid and containing 40 to 70% by weight of an aromatic monomer; And a coating composition for topical use of the present invention, which is coated on the coating composition for undercoat described above, is provided.

According to another aspect of the present invention, there is provided a PCM multicolored steel sheet coated on at least one side with a primer layer formed of the primer coating composition on the primer layer and the primer layer formed of the primer coating composition.

When the coating composition according to the present invention is applied to a multi-color steel sheet, it is realized on various color materials while satisfying the coating film hardness, durability, chemical resistance and mechanical properties equal to or more than that of a conventional single color steel sheet, Can also be obtained. Further, the coating composition of the present invention enables a two coating (baking) system to improve the cost competitiveness by improving the cost of heat energy due to the reduction of the number of oven usage, An improvement effect can be obtained.

Fig. 1 is a graph showing the results obtained when the undercoating composition of Comparative Example 1 was used (left) and the undercoating composition of Example 3 of the present invention was used, and when Production Example 2-A was applied by a wet on wet method It is a photograph comparing appearance.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the embodiments of the present invention can be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below.

According to the present invention, it is possible to coat on a primer coating composition (wet on wet system), and to provide an image which can be satisfactory in both appearance and physical properties, There is provided an anti-corrosive coating composition. Particularly, when the coating composition for phase-inversion of the present invention is used, the overlapping of color boundaries can be minimized.

More specifically, the coating composition for topical use of the present invention comprises a thermosetting polyester resin which is produced by a condensation reaction of a polyhydric alcohol with a divalent alcohol and contains the polyhydric alcohol-derived moiety in an amount of 25 to 40% by weight.

In particular, the thermosetting polyester resin used in the present invention has a linear monomer as a main axis for adjusting the appearance and a multi-color interface, and has a weight average molecular weight of 12,000 to 14,000, a hydroxyl value of 30 to 40 mgKOH / g, 5 mgKOH / g, and a glass transition temperature (Tg) of 15 to 25 ° C.

If the content of the polyhydric alcohol-derived moiety in the thermosetting polyester resin is less than 25% by weight, the molecular weight of the thermosetting polyester resin is low, and if it exceeds 40% by weight, the molecular weight of the thermosetting polyester resin increases. .

On the other hand, when the weight average molecular weight of the thermosetting polyester resin is less than 12,000, there is a problem of workability and durability. When the weight average molecular weight is more than 14,000, there is a problem in workability. In general, when the molecular weight is increased, the mechanical properties such as workability, impact and Erichsen characteristics are improved, but the viscosity is relatively increased, which may cause problems such as workability (dissolution power) and paint amount.

The coating composition for phase-inversion of the present invention contains a thermosetting polyester resin in an amount of 30 to 45% by weight. When the content is less than 30% by weight, there is a problem of workability and corrosion resistance. On the other hand, The hardness of the coating film and hiding power may be a problem.

The polyhydric alcohol may be at least one selected from the group consisting of neopentyl glycol, ethylene glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,7-heptanediol, 2-methyl-1,8-octanediol, and 1,10-decanediol, but the present invention is not limited thereto.

The dicarboxylic acid is preferably selected from the group consisting of isophthalic acid, terephthalic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid and terephthalic acid.

Further, the coating composition for undergarment of the present invention may further comprise at least one component selected from the group consisting of a crosslinking agent, a curing catalyst, an organic solvent , a rust preventive pigment, a leveling agent, an extender pigment, a dispersant additive and an epoxy resin.

More specifically, the topical coating composition of the present invention comprises 30 to 45% by weight of a thermosetting polyester resin, 3 to 10% by weight of a crosslinking agent, 0.5 to 2.5% by weight of a curing catalyst, 30 to 45% by weight of an organic solvent, , 1.5 to 3.5% by weight of a leveling agent, 2 to 4% by weight of an extender pigment, 0.1 to 0.2% by weight of a dispersing additive and 1 to 3% by weight of an epoxy resin.

The melamine resin is used alone as a crosslinking agent for forming a coating film with the resin component in the topical coating composition of the present invention to improve the hardness of the coating film and the scratch resistance.

The crosslinking agent is contained in an amount of 3 to 10% by weight based on the weight of the total phase coating composition. When the amount is less than 3% by weight, the curing is also problematic.

The curing catalyst is prepared by neutralizing a sulfonic acid selected from the group consisting of p-toluenesulfonic acid (p-TSA), dinonylnaphthalenesulfonic acid (DNNSA), dinaphthalene disulfonic acid (DNNDSA) and fluorosulfonic acid with an amine or epoxy, It is preferably a dissociation type curing agent having a temperature of 120 to 150 ° C. The use of Tin catalysts is excluded.

The curing catalyst is contained in an amount of 0.5 to 2.5% by weight based on the weight of the total phase coating composition. If the curing catalyst is less than 0.5% by weight, there is a problem in adhesion between the degree of curing and the undercoating, There is a problem with popping.

The coating composition of the present invention contains an organic solvent in consideration of characteristics during handling and coating. It is preferable that the organic solvent is at least one solvent selected from the group consisting of aromatic hydrocarbon-based, glycol ester-based, glycol ether-based and alcohol-based solvents.

The use of a ketone-based solvent to be applied to the composition for topical use of the present invention is excluded because the top coat may have a popping phenomenon when applying a ketone-based solvent.

Examples of the aromatic hydrocarbon-based solvent include cocosol # 100 and cocosol # 150 manufactured by SK Company. Examples of the glycol ester solvent include ethyl acetate, n-butyl acetate, cellosolve acetate, propylene glycol monomethyl Acetate, 3-methoxybutyl acetate, and the like. Examples of the glycol ether type solvent include methyl cellosolve, ethyl cellosolve, ethylene glycol butyl ether, diethylene glycol methyl ether, diethylene glycol ethyl ether, diethylene glycol butyl ether and the like of Union Carbide Co., Isopropanol, n-butanol, amyl alcohol, cyclohexanol and the like.

The solvent is contained in an amount of 30 to 45% by weight based on the weight of the total phase coating composition. If it is less than 30% by weight, there is a problem in workability. If it exceeds 45% by weight,

Particularly, when it is used as a coating composition for home appliances, it is preferable to mainly use an ester-based and aromatic hydrocarbon-based solvent to improve the storability and workability of the coating material and to make the environment-friendly characteristic.

In general, the top coating composition may include an inorganic pigment and / or an organic pigment including titanium dioxide (TiO ₂ ), iron oxide, carbon black, etc., and the content of the pigment may be varied depending on the color, Oil absorption and hiding power. However, it is preferably 5 to 30% by weight based on the weight of the total phase coating composition.

In order to maintain the smoothness of the coating film and to improve the foaming property during the coating operation, it is preferable that the acrylic, vinyl or silicone leveling agent is contained in an amount of 1.5 to 3.5% by weight in the present invention.

Examples of the leveling agent include, but are not limited to, URAD DD27 of DSM Chemical, BYK310, BYK322, BYK356, BYK410 of BYK, and CFC270, CFC90 of CFC Chemtell Corp., and the leveling agent may be used as a defoaming agent Can be used.

Particularly, the leveling agent useful in the phase change coating composition of the present invention has a solid content of 50 to 70% by weight, and when the solid content is less than 50% by weight, there is a problem of orange peeling of friability and appearance, If it exceeds 70% by weight, there is a problem in paint wettability. Considering the above, it is preferable to use a leveling agent having a solid content of 50% and a solid content of 70% in combination.

In order to further improve the hardness and weatherability of the coating composition of the present invention, at least one or more extender pigments such as talc, clay, silica, mica, alumina, calcium carbonate and the like may be further included. When the extender pigment is included, it is preferable that the extender pigment is included in an amount of 2 to 4% by weight based on the weight of the total topical paint composition.

The dispersion additive can be used to uniformly disperse the solid pigment in the liquid resin. When the dispersion of the pigment is insufficient, it may cause deterioration of properties such as pigment aggregation, precipitation and flow property. Therefore, May be added for improvement of properties. The content of the dispersing additive is preferably 0.1 to 0.2% by weight based on the weight of the total phase coating composition. The dispersing additive may be selected from the group consisting of a polycarboxylic acid copolymer, an acrylate copolymer and a phosphonic acid ester.

Further, when an epoxy resin is added to the paint composition for topical use, it is possible to improve workability, corrosion resistance, moisture resistance, and chemical resistance by improving the adhesion of the epoxy resin to the substrate and the undercoating, wherein the epoxy resin includes bisphenol A, At least one epoxy resin selected from the group consisting of bisphenol-A-bisphenol-A and phenoxy-type can be applied. The epoxy resin content is preferably 1 to 3% by weight based on the weight of the total phase coating composition.

On the other hand, according to the present invention, there is provided an undercoat paint composition comprising a thermosetting polyester resin produced by a condensation reaction of a polyhydric alcohol and a dicarboxylic acid and containing an aromatic monomer in an amount of 40 to 70% by weight, A coating composition for a PCM multicolored steel sheet comprising the coating composition for phase-inversion of any one of claims 1 to 15 is provided.

With respect to the above phase-change coating composition, as described above, a resin having an increased molecular weight is preferably used as a composition for undergarment relating to the composition for topical use of the present invention, and the proportion of aromatic components is maximized, And is intended to use a coating composition for undercoat which simultaneously satisfies color, appearance, workability, adhesion and the like.

More specifically, the undercoating paint composition which can be used in the present invention comprises a thermosetting polyester resin which is produced by a condensation reaction of a polyhydric alcohol and a dicarboxylic acid, and contains 40 to 70% by weight of an aromatic monomer.

The thermosetting polyester resin used in the undercoat paint composition preferably has a weight average molecular weight of 20,000 to 30,000, a hydroxyl value of 20 to 50 mgKOH / g, an acid value of 1 to 5 mgKOH / g, a glass transition temperature (Tg) of 45 to 55 < 0 > C.

When the weight average molecular weight of the thermosetting polyester resin is less than 20,000, it is difficult to maintain the durability of the coating film. When the weight average molecular weight exceeds 30,000, the workability is deteriorated.

The aromatic monomer is preferably an aromatic monomer of the BIS type and may be selected from the group consisting of, for example, polyoxyethylene bisphenol-A ether and polyoxypropylene bisphenol-A ether, but is not limited thereto. If the content of the aromatic monomer is less than 40% by weight based on 100% of the total weight of the thermosetting polyester resin, it is difficult to maintain the durability and dryness of the coating film. If the content of the aromatic monomer exceeds 70% by weight, .

The coating composition for undercoating of the present invention is contained in an amount of 25 to 35% by weight of a thermosetting polyester resin. When the content of the thermosetting polyester resin is less than 25% by weight, durability and dryness of the coating film are lowered. On the other hand, There is a problem that the resin component is excessively increased in the coating composition and the drying degree of the coating film is lowered.

The polyhydric alcohol may be at least one selected from the group consisting of neopentyl glycol, ethylene glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,7-heptanediol, 2-methyl-1,8-octanediol, and 1,10-decanediol, but the present invention is not limited thereto.

The dicarboxylic acid is preferably selected from the group consisting of isophthalic acid, terephthalic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid and terephthalic acid.

Further, the coating composition for undercoat which can be applied to the present invention further comprises at least one component selected from the group consisting of a crosslinking agent, a curing catalyst, an organic solvent , a rust preventing pigment, a leveling agent, an extender pigment, a dispersant additive and an epoxy resin .

More specifically, the coating composition for undercoat which can be applied to the present invention comprises 25 to 35% by weight of a thermosetting polyester resin, 3 to 13% by weight of a crosslinking agent, 0.5 to 2.5% by weight of a curing catalyst, 30 to 45% 5 to 10% by weight of a pigment, 0.5 to 3.5% by weight of a leveling agent, 2 to 4% by weight of an extender pigment, 0.1 to 0.2% by weight of a dispersing additive and 1 to 3% by weight of an epoxy resin.

The melamine resin and isocyanate resin are simultaneously applied as the crosslinking agent for forming a coating film with the resin component in the undercoat paint composition applicable to the present invention. The cross-linking agent of the present invention may be a blocked isocyanate resin with a methoxy melamine resin, preferably a mixture of the melamine resin and an isocyanate resin in a weight ratio of 1: 0.2 to 0.4.

When the melamine resin is used alone as the crosslinking agent, the strength of the coating film is excellent, but the processability and adhesion of the coating film are relatively weak. On the other hand, when the isocyanate resin is used alone, the processability and adhesion are excellent, . Accordingly, the present invention uses a methoxymelamine resin having a fast curing reaction rate and excellent curing reactivity when mixed with an acid catalyst, and a blocked isocyanate resin. If the amount of the blocked isocyanate resin is less than 0.2 part by weight based on 1 part by weight of the methoxy melamine resin, there is a disadvantage in that the processability and corrosion resistance of the coating film are deteriorated. If the amount exceeds 0.4 parts by weight, have.

The crosslinking agent is contained in an amount of 3 to 13% by weight based on the weight of the entire undercoat paint composition applicable to the present invention. When the crosslinking agent is less than 3% by weight, there is a problem of hardening. When the crosslinking agent is more than 13% have.

The curing catalyst is a catalyst obtained by neutralizing a sulfonic acid selected from the group consisting of a Tin catalyst or p-toluenesulfonic acid (p-TSA), dinonylnaphthalenesulfonic acid (DNNSA), dinaphthalene disulfonic acid (DNNDSA), and fluorosulfonic acid with an amine or epoxy And a dissociation type curing agent having a dissociation temperature of 120 to 150. The Tin catalyst may be dibutyl tin dilaurate (DBTDL) or the like and is preferably used for urethane crosslinking.

The curing catalyst is contained in an amount of 0.5 to 2.5% by weight based on the weight of the entire coating composition for undercoating. When the amount is less than 0.5% by weight, there is a problem in the degree of curing. When the amount is more than 2.5% by weight,

The coating composition of the present invention contains an organic solvent in consideration of characteristics during handling and coating. The organic solvent is preferably at least one solvent selected from the group consisting of aromatic hydrocarbon solvents, glycol ester solvents, ketone solvents, glycol ether solvents and alcohol solvents.

Examples of the aromatic hydrocarbon-based solvent include cocosol # 100 and cocosol # 150 manufactured by SK Company. Examples of the glycol ester solvent include ethyl acetate, n-butyl acetate, cellosolve acetate, propylene glycol monomethyl Acetate, 3-methoxybutyl acetate, and the like. Examples of the glycol ether type solvent include methyl cellosolve, ethyl cellosolve, ethylene glycol butyl ether, diethylene glycol methyl ether, diethylene glycol ethyl ether, diethylene glycol butyl ether and the like of Union Carbide Co., Isopropanol, n-butanol, amyl alcohol, cyclohexanol and the like.

The solvent is contained in an amount of 30 to 45% by weight based on the total weight of the coating composition. When the amount is less than 30% by weight, there is a problem in workability. When the amount is more than 45% by weight,

Particularly, when it is used as an undercoating paint composition, it is preferable to mainly use an ester-based and a ketone-based solvent to improve the storage stability and workability (pick-up property) of the paint and to take advantage of environmentally friendly characteristics.

The rust-preventive pigment is preferably selected from the group consisting of strontium chromate, a complex of amorphous silicon dioxide and calcium, magnesium oxide and zinc phosphate, and it is preferable that the household appliance is provided with corrosion resistance by applying non-toxic rust preventive pigment or the like. For example, raw materials of SOCIETE NOUVELLE DES COULEURS ZINCIQUES can be used for the chromate-free rust-preventive pigment applied to the undercoat paint for construction materials, and the non-toxic rust-preventive pigment applied to the undercoat paint for home electric appliances is a composite of atypical silicon dioxide and calcium At the same time, corrosion resistance can be improved.

Generally, the corrosion resistance of the cross section is improved as the content of the anticorrosive pigment is increased in the case of the undercoat paint composition. However, when the anticorrosive pigment is used in an excessive amount, the probability of occurrence of the blister (BLISTER) It is preferable that the content of the anticorrosive pigment is 5 to 10% by weight based on the weight of the total paint composition.

In order to maintain the smoothness of the coating film and to improve the foaming property during the coating operation, it is preferable that the acrylic, vinyl or silicone leveling agent is contained in an amount of 0.5 to 3.5 wt%, respectively.

Examples of the leveling agent include, but are not limited to, URAD DD27 of DSM Chemical, BYK310, BYK322, BYK356, BYK410 of BYK, and CFC270, CFC90 of CFC Chemtell Corp., and the leveling agent may be used as a defoaming agent Can be used.

The coating composition of the present invention may also be used as a clear coating composition containing no pigment, but may include a pigment if necessary, and the pigment may be selected from the group consisting of titanium dioxide, RED iron oxide and YELLOW iron oxide , And the pigment is preferably contained in an amount of 2 to 4% by weight based on the weight of the whole undercoating paint composition.

Clay, silica, mica, alumina and the like in order to further improve the adhesion to the substrate and the corrosion resistance, And the like.

The dispersion additive can be used to uniformly disperse the solid pigment in the liquid resin. When the dispersion of the pigment is insufficient, it may cause deterioration of properties such as pigment aggregation, precipitation and flow property. Therefore, May be added for improvement of properties. The content of the dispersing additive is preferably 0.1 to 0.2% by weight based on the total weight of the coating composition for undergarment.

Further, when an epoxy resin is added to the undercoat paint composition, the adhesion to the substrate can be improved to improve workability, corrosion resistance, moisture resistance and chemical resistance. Examples of the epoxy resins include bisphenol A, hydrogenated bisphenol At least one epoxy resin selected from the group consisting of -A and phenoxy type can be applied. The epoxy resin content is preferably 1 to 3% by weight based on the weight of the entire coating composition.

According to another aspect of the present invention, a coating composition for a PCM multicolor steel sheet of the present invention as described above is used to form a primer layer formed of the primer coating composition and a primer layer formed of the primer coating composition on the primer layer, A PCM multicolored steel sheet painted on a steel plate is provided.

As such, in the case of the coating composition for undercoats to be used together with the coating composition for topical use of the present invention, a composition other than the above-mentioned thermosetting polyester resin may be common to some of the composition for topical use of the present invention.

In the case of applying the paint composition for top and bottom use according to the present invention, it is possible to solve the drying and workability problems that may occur when applying 2 coating 1 baking system. That is, it is possible to improve the phenomenon of breakage of the external coating film and the color overlapping of the multi-color boundary surface in the system for painting the upper surface on the lower surface of the wet state.

Hereinafter, the present invention will be described more specifically by way of specific examples. The following examples are provided to aid understanding of the present invention, and the scope of the present invention is not limited thereto.

Example

1. Preparation of thermosetting polyester resin

(1) Coating composition for topcoat

(1,6-hexanediol, neopentyl glycol) and a dicarboxylic acid (isophthalic acid, terephthalic acid) are mixed with the SN catalyst (BUTYL STANNOIC ACID) was added to perform condensation reaction.

(Ethylene glycol, neopentyl glycol, 1,6-hexanediol), dicarboxylic acid (isophthalic acid, terephthalic acid, adipic acid) and SN catalyst (BUTYL STANNOIC ACID) were added to the resin tank The mixture is subjected to a first reaction at a temperature of 210 to 230 ° C for 13 hours, and then a diluting solvent is further added thereto at a temperature of 180 to 200 ° C for 3 hours to proceed with a second reaction and viscosity adjustment.

The more specific contents of each component used herein are shown in Table 1 below same.

ingredient Example 1 Example 2 Example 3 Example 4 Polyhydric alcohol Ethylene glycol 8.0 g 10 g 12.0 g 13.0 g Neopentyl glycol 22.0 g 17.0 g 18.0 g 16.0 g 1,6-hexanediol 5.0 g 6.0 g 4.0 g 3.0 g 2-valent acid Isophthalic acid 38.0 g 35.0 g 33.0 g 36.0 g Terephthalic acid 10.0 g 14.0 g 16.0 g 14.0 g Adipic acid 14.0 g 15.0 g 13.0 g 12.0 g additive BUTYL STANNOIC ACID 0.1 g 0.1 g 0.1 g 0.1 g Diluting solvent K100 / CYCLOHEXANONE
= 6/4 48g 47g 48g 47g importance 1.05 1.05 1.05 1.05 Viscosity V2 V1 V1- V1- Solid content (%) 50.3 50.6 50.2 50.1 Acid value 2.5 2.1 2.1 2.2 The weight average molecular weight (Mw, GPC) 13,000 12,500 12,500 13,000 Hydroxyl value 33 38 35 39 Viscosity: 50% solution (25 캜 Gardner), 50% dilution solvent, relative evaluation with Gardner viscometer

(2) Paint composition for undercoats

In order to prepare a thermosetting polyester resin to be used for a coating composition for undercoating, a polyhydric alcohol and a dicarboxylic acid are mixed, and a BIS type aromatic monomer (2,2-bis (4-hydroxyphenyl) Ether) was added to perform condensation reaction.

The content of each component used herein is shown in Table 2 below same. (BA320T), polyhydric alcohol (neopentyl glycol & ethylene glycol), dicarboxylic acid (isophthalic acid), and an additive (DBTO) were mixed in the resin tank before the raw material introduction, (Terephthalic acid) and a diluting solvent are further added at a temperature of 210 to 215 ° C for 3 hours, followed by a second-order reaction and viscosity adjustment.

ingredient Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Aromatic monomer BA320T 48.0 g 54.0 g 60.0 g 65.0 g - Polyhydric alcohol Neopentyl glycol 10.0 g 8.0 g 6.0 g 4.5 g 34.0 g Ethylene glycol 2.5 g 2.0 g 2.5 g 2.5 g - Trimethylpropanol - - - - 6.0 g 2-valent acid Isophthalic acid 10.0 g 15.0 g 20.0 g 25.0 g 35.0 g Terephthalic acid 25.0 g 20.0 g 15.0 g 10.0 g 6.0 g Adipic acid 20 g additive DBTO 0.1 g 0.1 g 0.1 g 0.1 g 0.1 g Diluting solvent K100 / PMA = 1/1 48 g 49 g 51 g 52 g 41 g importance 1.05 1.05 1.05 1.05 1.05 Viscosity Z + Z1 Z1- Z1 + X Solid content (%) 49.7 50.2 50.1 50.5 60.0 Acid value (mg-KOH / g) 1.5 1.6 1.1 1.2 5.0 Weight average molecular weight (Mw) 24,200 23,900 23,500 23,600 15,000 Hydroxyl value (mg-KOH / g) 25 24 26 25 40 BA320T: 2,2-bis (4-hydroxyphenyl) propane diallyl ether
DBTO: Dibutyltin oxide
Viscosity: 50% solution (25 캜 Gardner), 50% dilution solvent, relative evaluation with Gardner viscometer

That is, as in Comparative Example 1, the thermosetting polyester resin used in the conventional undercoat paint composition had a solid content of about 60% by weight, a viscosity of VY, a molecular weight of 14000-16000, a hydroxyl value of 10-60, 40 ° C. In the case of the thermosetting polyester resin used for the undercoating composition of the present invention, the solid content is about 50% by weight, the viscosity is Z-Z3, the molecular weight is 20,000-30000, the hydroxyl value is 20-50, 55 deg. C, and their physical properties are distinguished.

2. Preparation of Coating Composition of PCM Multicolor Steel Sheet

(1) Preparation of topcoat paint composition

The thermosetting polyester resin prepared in (1) above, the dispersing additive, the pigment and the extender pigment are mixed at a temperature of 70 ° C or lower by a milling process, and then the epoxy resin and the crosslinking agent are added at a temperature of 35 ° C or lower, (Stir). Then, a leveling agent and a curing catalyst were added and stirred, and finally, an organic solvent was applied to prepare a composition for topical application. The content of each component used is shown in Table 3 below.

[ Table 3 ]

* Unit: g

(2) Preparation of coating composition for undercoat

The thermosetting polyester resin, the dispersant, the extender pigment, and the anticorrosive pigment prepared in the above item (2) are mixed at a temperature of 70 ° C or lower by a milling process. Thereafter, the epoxy resin and the crosslinking agent are slowly added Stir. Then, a leveling agent and a curing catalyst were added and stirred, and finally, an organic solvent was applied to prepare a composition for undercoating. The content of each component used is shown in Table 4 below.

Item ingredient Multicolor (paint) coating paint Item ingredient Production Example 1 Production Example 2 Production Example 3 Production Example 4 Comparative Preparation Example 1 Suzy Polyester resin 43 g 43 g 43 g 43 g 43 g Dispersant additive Polycarboxylic acid copolymer 0.15 g 0.15 g 0.15 g 0.15 g 0.15 g Extender pigment Silica, aluminum silicate 4 g 4 g 4 g 4 g 4 g Anticorrosive pigment Strontium chromate 7 g 7 g 7 g 7 g 7 g Epoxy resin Bisphenol-A 1.5 g 1.5 g 1.5 g 1.5 g 1.5 g Cross-linking agent Hexamethoxymethyl melamine 4 g 4 g 4 g 4 g 4 g Cross-linking agent Isocyanate 2 g 2 g 2 g 2 g 2 g Leveling agent acryl 2 g 2 g 2 g 2 g 2 g Curing catalyst Sulfonic acid (acid catalyst) 1.5 g 1.5 g 1.5 g 1.5 g 1.5 g Curing catalyst DBTDL (Tin Catalyst) 0.15 g 0.15 g 0.15 g 0.15 g 0.15 g Organic solvent DIBASIC ESTER 7.7 g 7.7 g 7.7 g 7.7 g 7.7 g Organic solvent CYCLOHEXANONE 9 g 9 g 9 g 9 g 9 g Organic solvent KOCOSOL 100 10 g 10 g 10 g 10 g 10 g Organic solvent KOCOSOL 150 8 g 8 g 8 g 8 g 8 g

3. Coating composition Painted  Experiment to confirm the physical properties of PCM multicolored steel sheet

To prepare test specimens, 0.45 T GI steel sheets were degreased with methyl ethyl ketone, and the coating compositions for undercoats of Production Examples 1 to 4 of Table 4 were bar coated to a dry film thickness of about 5 탆. The physical properties were confirmed and are shown in Table 5 below.

Properties Coating composition for primer Production Example 1 Production Example 2 Production Example 3 Production Example 4 Comparative Preparation Example 1 importance 1.13 1.12 1.13 1.13 1.18 Solids 43.2 43.1 43.3 43.2 56.7 Viscosity (sec / 25'C) 70 70 70 70 70 Polish 15 15 15 15 15 Degree of hardening 10 10 8 10 10 Exterior ◎ ◎ ◎ ◎ ◎

Thereafter, the undercoating composition of Production Example 3 was used to paint, and furthermore, the paint composition for phase in Production Examples 1 to 4 of Table 3 was further coated. The topcoat paint composition was coated with an applicator to a dry film thickness of about 15 to 20 μm, and then baked at an atmospheric temperature of 280 ° C. for 40 seconds to prepare a final physical property test specimen.

At this time, the appearance of the undercoat composition of Production Example 3 and further coated with the topcoat composition of Production Example 2-A is the same as that shown in the right side of FIG.

After that, the properties of the final test specimens were confirmed and are shown in Table 6 below. That is, Table 6 assumes that the undercoating composition of Production Example 3 is applied.

Composition (% by weight) Multi-Color Top Coating Paints Example 1 Resin Example 2 Resin Example 3 Resin Example 4 Resin Production Example 1 Production Example 2 Production Example 3 Production Example 4 A B A B A B A B importance 1.21 1.21 1.21 1.21 1.21 1.21 1.21 1.21 Solids 48.3 48.2 48.3 48.1 48.5 48.3 48.4 48.2 Viscosity (sec / 25'C) 30 30 30 30 30 30 30 30 Polish 30 30 30 30 30 30 30 30 Degree of hardening 50 50 50 50 50 50 50 50 Exterior ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ Processability ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ Acid resistance ◎ ○ ◎ ○ ◎ ○ ○ ○ My alkalinity ◎ ○ ◎ ○ ○ ○ ◎ ○ Abdominal aquatic ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ Attachment ○ ○ ◎ ○ ◎ ○ ○ ○ Corrosion resistance ○ ○ ◎ ○ ◎ ○ ○ ○

On the other hand, when the coating composition for phase-inversion of Production Example 2-A was further coated by coating with the undercoating composition of Comparative Production Example 1 and the final physical property test specimen was prepared by the same procedure, Respectively.

In order to compare the above physical properties more clearly, the undercoating compositions of Preparative Example 3 and Comparative Preparative Example 1 were compared with each other for compositions for undercoat application of the phase inversion coating composition of Production Example 2-A.

Composition (% by weight) The phase change coating composition of Production Example 2-A The coating composition for undergarment of Comparative Production Example 1 The coating composition for undergarment of Production Example 3 Polish 26 30 Degree of hardening 50 50 Exterior X ◎ Processability △ ◎ Acid resistance X ◎ My alkalinity X ◎ Abdominal aquatic X ◎ Attachment △ ◎ Corrosion resistance △ ◎

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be obvious to those of ordinary skill in the art.

Claims (21)

A coating composition for undercoating comprising a thermosetting polyester resin produced by a condensation reaction of a polyhydric alcohol and a dicarboxylic acid, wherein the thermosetting polyester resin has an aromatic monomer content of 40 to 70 wt% and a glass transition temperature (Tg) of 45 to 55 DEG C; And
A coating composition for topical application coated on a primer layer formed from the primer coating composition, which comprises a thermosetting poly (poly (meth) acrylate) containing 25 to 40% by weight of a polyhydric alcohol - derived moiety, A coating for PCM multicolor steel sheet for two coatings 1 baking, comprising an ester coating composition comprising an ester resin.
The thermosetting polyester resin composition according to claim 1, wherein the thermosetting polyester resin of the phase change coating composition has a weight average molecular weight of 12,000 to 14,000, a hydroxyl value of 30 to 40 mg KOH / g, an acid value of 1 to 5 mg KOH / g, Tg) of 15 to 25 占 폚.
The coating composition according to claim 1, wherein the polyhydric alcohol of the topical coating composition is at least one selected from the group consisting of neopentyl glycol, ethylene glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,7- -Content diol, 1,9-nonanediol, 2-methyl-1,8-octanediol, and 1,10-decanediol.
The dyestuff of claim 1, wherein the dicarboxylic acid of the topical coating composition is selected from the group consisting of isophthalic acid, terephthalic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid and terephthalic acid. Coatings for multi-colored steel plates.
2. The coating composition according to claim 1, wherein the topical coating composition further comprises at least one component selected from the group consisting of a crosslinking agent, a curing catalyst, an organic solvent, a pigment, a leveling agent, an extender pigment, Coatings for steel plates.
The coating composition according to claim 1, wherein the topical coating composition comprises 30 to 45% by weight of the thermosetting polyester resin, 3 to 10% by weight of a crosslinking agent, 0.5 to 2.5% by weight of a curing catalyst, 30 to 45% by weight of an organic solvent, Wherein the leveling agent comprises 1.5 to 3.5% by weight of an extender pigment, 2 to 4% by weight of an extender pigment, 0.1 to 0.2% by weight of a dispersing additive and 1 to 3% by weight of an epoxy resin.
The paint for a PCM multicolor steel sheet according to claim 5, wherein the crosslinking agent is a melamine resin.
6. The method of claim 5, wherein the curing catalyst is selected from the group consisting of sulfonic acids selected from the group consisting of p-toluenesulfonic acid (p-TSA), dinonylnaphthalenesulfonic acid (DNNSA), dinaphthalene disulfonic acid (DNNDSA), and fluorosulfonic acid with amine or epoxy And a dissociation type curing agent having a dissociation temperature of 120 to 150 ° C.
6. The paint for a PCM multicolor steel sheet according to claim 5, wherein the organic solvent is at least one solvent selected from the group consisting of aromatic hydrocarbon-based, glycol ester-based, ketone-based, glycol ether-based and alcohol-based solvents.
The paint for a PCM multicolor steel sheet according to claim 5, wherein the pigment is at least one selected from the group consisting of an organic pigment and an inorganic pigment.
The paint for a PCM multicolor steel sheet according to claim 5, wherein the leveling agent is an acrylic, vinyl or silicone leveling agent.
12. The coating material for a PCM multicolor steel sheet according to claim 11, wherein the leveling agent has a solid content of 70 to 50% by weight.
The paint for a PCM multicolor steel sheet according to claim 5, wherein the extender pigment is selected from the group consisting of calcium carbonate, aluminum silicate and silica.
6. The paint of claim 5, wherein the dispersing additive is selected from the group consisting of a polycarboxylic acid copolymer, an acrylate copolymer and a phosphoric acid ester.
The paint for a PCM multicolor steel sheet according to claim 5, wherein the epoxy resin is selected from the group consisting of bisphenol-A, hydrogenated bisphenol-A and phenoxy.
delete The coating material for a PCM multicolor steel sheet according to claim 1, wherein the thermosetting polyester resin of the undercoat paint composition has a weight average molecular weight of 20,000 to 30,000, a hydroxyl value of 20 to 50 mgKOH / g and an acid value of 1 to 5 mgKOH / .
The coating composition according to claim 1, wherein the undercoating composition further comprises at least one component selected from the group consisting of a crosslinking agent, a curing catalyst, an organic solvent, a rust preventing pigment, a leveling agent, an extender pigment, Coatings for multi-colored steel plates.
The coating composition according to claim 18, wherein the coating composition for undercoat comprises 25 to 35 wt% of a thermosetting polyester resin, 3 to 13 wt% of a crosslinking agent, 0.5 to 2.5 wt% of a curing catalyst, 30 to 45 wt% of an organic solvent, Wherein the leveling agent comprises 0.5 to 3.5% by weight of an extender pigment, 2 to 4% by weight of an extender pigment, 0.1 to 0.2% by weight of a dispersing additive and 1 to 3% by weight of an epoxy resin.
The paint for a PCM multicolor steel sheet according to claim 18, wherein the crosslinking agent is a mixture of a methoxy melamine resin and a blocked isocyanate resin in a ratio of 1: 0.2 to 0.4 by weight.
A undercoat layer formed of the undercoat paint composition using the paint for a PCM multicolour steel sheet of claim 1; And a top layer formed of the top coat paint composition on at least one side of the undercoat layer.

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