KR102015701B1 - Primer coating composition - Google Patents

Abstract

The present invention relates to an integrated undercoat coating composition for highly corrosion-resistant PCM (Pre-coated metal), by mixing two or more kinds of polyester resins having different molecular weights with a matting agent, thereby exhibiting excellent corrosion resistance and chemical resistance. The coating composition excellent in the adhesiveness which can be applied to a coating layer without a restriction | limiting to the coating component of a coating layer is provided.

Description

Primer coating composition {PRIMER COATING COMPOSITION}

The present invention relates to an integrated undercoat coating composition for high corrosion resistance PCM (pre-coated metal) that can be applied to the undercoat without limitation to the paint component of the top coat.

PCM flooring for building exterior materials is applied to roofs, walls, shutters, etc. of buildings, and they are exposed to severe corrosive environments outdoors. Accordingly, as a building exterior material is excellent workability is required to minimize the cracks during processing, to increase the adhesion to the material and to minimize the corrosion in the crack portion is required.

PCM undercoat for building exterior materials is generally used for polyester top paint and fluorine top paint, but in recent years, it has been attempted to integrate the two paints mentioned above for the purpose of efficiency and cost reduction. As an example of such an integrated high corrosion resistance undercoat composition, Japanese Patent No. 3076496 discloses an integrated undercoat containing a polyester resin, a novolak type epoxy resin, a curing agent, an antirust pigment, an organic solvent, and the like. However, in the case of the integrated undercoating paint, the excessive use of the rust preventive pigment not only raises the raw material cost of the paint, but also causes a problem of deterioration in adhesion with the fluorine-based topcoat.

The present invention is to provide an integrated undercoat coating composition for highly corrosion-resistant PCM that can improve the corrosion resistance and adhesion to the fluorine-based topcoat than conventional, despite reducing the content of the rust preventive pigment.

The present invention is based on 100% by weight of the paint composition, 20-50% by weight polyester resin, 5-15% by weight epoxy resin, 3-10% by weight melamine resin, 0.1-1.0% by weight acid catalyst, anti-rust pigment 5- An integrated undercoat coating composition for high corrosion resistance PCM is provided, comprising 15% by weight, quencher 1-5% by weight, and a residual solvent.

The present invention also provides a PCM steel sheet comprising a steel sheet and at least one coating layer formed on the surface of the steel sheet, wherein a lower layer of the at least one coating layer is a cured product formed from the above-mentioned integrated coating composition for PCM. do.

The integrated undercoat coating composition for PCM of the present invention can secure high corrosion resistance required for building exterior materials without applying excessive rust preventive pigments, and can exhibit excellent chemical resistance and good adhesion with a fluorine-based top coat. In addition, the integrated undercoat coating composition for PCM of the present invention is applicable to the integrated undercoat regardless of the components of the topcoat due to its excellent adhesion, and can be usefully used for building interior and exterior materials by showing the effect of promoting adhesion with the fluorine-based topcoat layer. have. Accordingly, the integrated undercoat composition for PCM of the present invention can be used universally for the purpose of the universal primer applied to interior and exterior building materials.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail. However, the present invention is not limited only to the following contents, and each component may be variously modified or optionally mixed as necessary. Therefore, it is to be understood that all changes, equivalents, and substitutes included in the spirit and scope of the present invention are included.

Integrated Coating Composition for PCM

The integrated undercoat composition for PCM according to the present invention comprises a polyester resin, an epoxy resin, a melamine resin (curing agent), an acid catalyst, an rust preventive pigment, a quencher and a solvent, but having a specific particle size and two kinds of polyester resins having different molecular weights. Use a mixed quencher. If necessary, additives such as pigments such as colored pigments and powder pigments, and dispersants, leveling agents and adhesion improving agents may be further included.

Hereinafter, the composition of the integrated undercoat composition for PCM will be described in detail.

Polyester resin

In the integrated undercoat composition for PCM according to the present invention, a polyester resin is used as the main resin. The main resin reacts with the curing agent to form a coating film, to give gloss, and to secure basic physical properties, high corrosion resistance, processability, chemical resistance, hardness, and adhesion of the coating film.

In the present invention, two kinds of polyester resins having different physical properties such as molecular weight (Mn) and glass transition temperature (Tg) are mixed as polyester resins, thereby securing high corrosion resistance and adhesion required as integrated undercoat for PCM. can do.

The first polyester resin has a number average molecular weight (Mn) of 6,000-8,000 g / mol, for example, 6,500-7,500 g / mol. In addition, the hydroxyl value (OHv) may be in the range of 13-23, the glass transition temperature (Tg) is 20-30 ℃. The second polyester resin has a number average molecular weight (Mn) of 2,000-4,000 g / mol, for example, 2,500-3,500 g / mol. In addition, the hydroxyl value (OHv) may be 40-50, the glass transition temperature (Tg) may be 35-45 ℃.

According to one embodiment of the present invention, the mixing ratio (weight ratio) of the first polyester resin and the second polyester resin may be 40: 60-60: 40. When two or more kinds of polyester resins having different number average molecular weights (Mn) and glass transition temperatures (Tg) are mixed at an appropriate ratio, the solid content in the paint may be increased to show excellent coating properties in terms of corrosion resistance, weather resistance, and hardness. have.

In the present invention, the content of the polyester resin is not particularly limited, and may be, for example, 20 to 50% by weight based on the total weight of the coating composition. When the content of the polyester resin falls within the above range, the basic physical properties of the coating film is good, it exhibits excellent corrosion resistance, chemical resistance and appearance properties, and can improve the adhesion with other substrate layers.

Epoxy resin

In the integrated undercoat composition for PCM according to the present invention, an epoxy resin is used as a main resin together with a polyester resin to impart adhesion with a base to a coating film.

As the epoxy resin, conventional epoxy resins known in the art may be used without limitation. According to an embodiment, the epoxy resin may be an epoxy resin having a number average molecular weight (Mn) of 300 to 500 and an equivalent weight of 180 to 200.

Non-limiting examples of epoxy resins that can be used include phenol, cresol, xylenol, propylphenol, nonylphenol, hydroquinone, resorcinol, methoxyphenol, bromophenol, bisphenol A, bisphenol F, phosphate epoxy resin or And mixtures of two or more thereof. As an example, the diglycidyl ether type epoxy resin obtained from epichlorohydrin and bisphenol A can be used.

In the present invention, the content of the epoxy resin is not particularly limited, and may be, for example, 5 to 15% by weight based on the total weight of the coating composition. When the content of the epoxy resin falls within the above range, the basic physical properties of the coating film is good, it may exhibit excellent corrosion resistance, chemical resistance, adhesion.

Melamine resin

In the integrated undercoat composition for PCM according to the present invention, the melamine resin serves as a curing agent (crosslinking agent) for curing the above-described polyester resin or epoxy resin component to form a stable coating film.

Melamine resin is a substance obtained for polymerization of alcohol and formaldehyde. For example, methoxy melamine resin is a polymerization of methanol and formaldehyde, and a methoxy / butoxy mixed melamine resin is a mixture of methanol and isobutanol or normal butanol and formaldehyde. Can be obtained by polymerization.

Non-limiting examples of the melamine resin usable in the present invention include methoxy melamine resin, methoxy / butoxy mixed melamine resin and the like. The number average molecular weight of the melamine resin may be in the range of 300 to 1,000, for example.

The content of the melamine resin in the present invention may be 3 to 10% by weight based on the total weight of the coating composition. When the content of the melamine resin is less than 3% by weight, the degree of curing, fouling resistance, chemical resistance, weather resistance, etc. of the coating film is lowered, and when it exceeds 10% by weight, the flexibility, impact resistance, and weather resistance of the coating film may be lowered. .

Acid catalyst

In the integrated undercoat composition for PCM according to the present invention, the acid catalyst acts as a curing accelerator to improve the density of the coating film by promoting the curing of the polyester resin and the curing agent (melamine resin).

Acid catalysts that can be used include sulfonic acid compounds, and non-limiting examples include para-toluenesulfonic acid (p-TSA), dinonylnaphthalenesulfonic acid (DNNSA), dinonylnaphthalene disulfonic acid (DDBSA), and dodecylbenzenesulfonic acid (DDBSA). There is this. These may be used alone or in combination of two or more thereof.

The content of the acid catalyst in the present invention may be 0.1 to 1.0% by weight based on the total weight of the paint composition. If the content of the acid catalyst is less than 0.1% by weight uncured, there is a disadvantage in that hardness, chemical resistance, and weather resistance is lowered, when the content of more than 1.0% by weight of the coating film is too hard to workability or unreacted acid catalyst remains in the coating film When the coating is exposed to the external environment, it promotes aging of the coating due to hydrolysis.

Pigment

The integrated undercoat composition for PCM according to the present invention comprises an rust preventive pigment. The anti-corrosive pigment is a material to which the corrosion resistance is improved, and conventional chromium pigments and non-chromium pigments known in the art may be used. Non-limiting examples of the chromium-based pigments include strontium chromium, calcium chromium, barium chromium, zinc chromium potassium, zinc tetrachloride, and the like. Non-limiting examples of the non-chromic pigments include calcium silica, zinc phosphate, and organic. Nitro compound zinc salt, calcium silicate, zinc potassium and the like. The above-mentioned components may be used alone or in combination of two or more thereof. In particular, the use of chromium-based pigments are effective in harsh corrosive environments, non-toxic pigments such as calcium silica can be used in accordance with the regulations on toxic substances, and in some cases it may be used by mixing chromium-based pigments and non-chromium pigments. .

Conventionally, the undercoat coating composition for building materials used an excessive rust preventive pigment in order to exhibit high corrosion resistance. In this case, not only the raw material cost of the paint increased but also the adhesiveness with the fluorine-based top coat was inferior. On the other hand, in the present invention, even though the content of the rust preventive pigment based on the total weight of the coating composition to 16% by weight or less can exhibit excellent corrosion resistance effect. In the present invention, the rust preventive pigment may be 16% or less based on the total weight of the coating composition, for example, 5 to 15% by weight. If the content of the rust preventive pigment is less than 5% by weight, the corrosion resistance is not sufficient, and if the content exceeds 16% by weight, the adhesion may be lowered, and the boiling resistance and workability of the coating film may be lowered.

The coating composition of the present invention may further include pigments such as conventional extender pigments and colored pigments used in the field of PCM coating compositions, in addition to the above-described rust preventive pigments, in the range of not impairing the effects of the present invention. Pigments including such rust preventive pigments may be added to the composition in amounts known in the art, for example from 10 to 20% by weight based on the total weight of the paint composition.

The extender pigment fills the pores in the coating film, complements the coating film formation, and plays a role in imparting a salvage or mechanical property to the coating film. Therefore, when the extender pigment is further included, a good coating appearance can be obtained and hardness, impact resistance, rust resistance and the like can be improved.

As a extender pigment, those conventionally used in paint compositions for PCM may be used without limitation, and non-limiting examples include calcium carbonate, clay, talc, magnesium silicate, kaolin, mica, silica, aluminum silicate, aluminum hydroxide, Barium sulfate, barium sulfate and the like. The above-mentioned components may be used alone or in combination of two or more thereof. The particle size of the extender pigment is not particularly limited, and may be appropriately adjusted within the usual particle size range applied to the PCM coating composition. In one example, an average particle diameter of 500-1,000 nm can be used. The extender pigment content may be 1 to 5% by weight based on the total weight of the paint composition. When the content of the extender pigment is less than 1% by weight, the hardness of the coating film may be lowered, and when the content of the extender pigment is more than 5% by weight, the adhesion may be slightly lowered, and the cured coating film may generate fine cracks and adversely affect the water resistance.

Colored pigments may be added for the purpose of expressing the desired color in the paint. As the colored pigment, organic pigments, inorganic pigments, metallic pigments, aluminum pastes (Al-paste), pearls, etc., which are commonly used in PCM building material coating, may be used without limitation, and these may be used alone or in combination of two or more. can do.

The inorganic pigment may be at least one selected from the group consisting of compounds such as aluminum, silicon, zinc, titanium, manganese, iron and chromium, oxides thereof and hydroxides, sulfates, chromates and phosphate compounds. Non-limiting examples of inorganic pigments that can be used include titanium oxide white, iron oxide, carbon black, titanium oxide, barium sulfate, zinc oxide, zinc, bengal, sulfur lead, cadmium yellow, lead cyanamide, and chromic acid. Strontium chromate, Titanium yellow, Red red, Copper oxide, Copper oxide, Vermillion, Cadmium red, Royal blue, Cobalt blue, Mineral violet, Cobalt Cobalt violet deep, chromium green, chromium oxide green, chromium hydroxide, zinc rust, gold powder, silver powder, zinc powder or a mixture of two or more thereof.

Non-limiting examples of organic pigments that can be used include Dioxazine, Phthalo Cyanine Blue, Azo (Mono, Disazo Yellow, Azo, Hansa Yellow ( Hansa yellow, Benzidine yellow, Permanent yellow, Toluidine red, Lake Red C, Watching red, Quinacridone, Copper phthalocyanine Green (Cu-phthalocyanine green) or a mixture of two or more thereof.

The content of the colored pigment in the present invention may be 1 to 5% by weight based on the total weight of the paint composition. When the content of the colored pigment is less than 1% by weight, the appearance of the color may be deteriorated due to the insignificant color, and when the content is more than 5% by weight, the dispersibility, storage stability, and the basic physical properties of the paint may be reduced.

solvent

The integrated undercoat composition for PCM according to the present invention can use any organic solvent known in the art as a solvent without limitation. The organic solvents include aromatic hydrocarbons, ester solvents, ether solvents, alcohol solvents or mixtures thereof.

Non-limiting examples of organic solvents that can be used include Cocosol # 100 (Kocosol # 100, K-100, SK Energy Co., Ltd.), Cocosol # 150 (Kocosol # 150, K-150, SK Energy Co., Ltd.), cyclohexa Paddy, xylene, toluene, cellosolve acetate, methylethylketone, dibasic ester, propylene glycol methylether acetate, n-butyl acetate, propylene glycol monomethyl acetate, 3-methoxy butyl acetate, ethylene glycol butyl ether, diethylene Glycol methyl ether, diethylene glycol ethyl ether, diethylene glycol butyl ether, ethanol, isopropanol, n-butanol, amyl alcohol or a mixed solvent thereof.

In the present invention, the content of the organic solvent may be a residual amount that satisfies the total weight (eg, 100% by weight) of the coating composition, for example, 5 to 20% by weight based on the total weight of the coating composition. have. When the content of the solvent falls within the above-described range, workability may be improved and excellent physical properties of the coating film may be exhibited.

additive

Integrated undercoat compositions for PCM according to the present invention may include conventional quencher known in the art. Non-limiting examples of usable matting agents include Synthesized Silica matting agents, polypropylene matting agents, polyethylene matting agents, or mixtures thereof.

The matting agent is generally added to the coating composition in order to scatter light at the surface of the coating film and to reduce gloss. On the other hand, in the present invention, the surface roughness Ra of the undercoat is increased to increase the surface area, whereby a matting agent powder having a predetermined particle size is used to improve adhesion with the top coat. The average particle diameter of the quencher powder blended in the coating composition of the present invention may be 5 to 15 ㎛, for example 9 to 12 ㎛.

The content of the matting agent in the present invention may be 1 to 5% by weight based on the total weight of the paint composition. When the content of the matting agent is less than 1% by weight, the surface roughness effect of the coating film is insignificant, and the adhesion may be lowered. When the content of the matting agent is more than 5% by weight, the dispersibility, storage stability, and the basic physical properties of the paint may be reduced.

In addition to the matting agent described above, the coating composition of the present invention may further include conventional additives used in the field of PCM coating compositions in a range that does not impair the effects of the invention.

Non-limiting examples of additives that can be used include dispersants, adhesion improvers, curing retardants, surface modifiers, antifoaming agents (e.g., dimethylpolysiloxanes), surfactants, softeners, thickeners, weather resistant additives, desiccants, appearance modifiers, leveling agents, absorbents, couplers Ring agents or mixtures thereof.

The dispersant serves to disperse each material constituting the composition and to prevent re-agglomeration through distance maintenance so as to express uniform physical properties of the coating film. As the dispersant, conventional ones known in the art may be used, and examples thereof include a high molecular weight block copolymer type dispersant.

An adhesion improving agent is used to promote the adhesion with the base of the coating film. Examples of adhesion improving agents that can be used include silane-based adhesion improving agents, polyester-based adhesion improving agents and mixtures thereof.

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

The leveling agent is for leveling the coating composition so that it is coated smoothly and smoothly, thereby improving the appearance properties of the coating film while enhancing the adhesion in the composition. As the leveling agent, conventional ones known in the art may be used without limitation, and examples thereof include acrylic, silicone, polyester, and amine leveling agents.

The additive including the matting agent may be added in an amount known in the art, for example, 2 to 20% by weight based on the total weight of the paint composition.

The integrated undercoat coating composition for PCM of the present invention may be prepared according to conventional methods known in the art, and for example, after the resin, the curing agent, the curing catalyst, the pigment, the additive, and the solvent of the above-mentioned composition are respectively constituted, It can be prepared by mixing in proportions.

<PCM steel plate>

Moreover, this invention provides the PCM steel plate provided with the coating film layer formed using the coating composition mentioned above.

The PCM steel sheet includes a steel sheet and at least one coating layer formed on a surface of the steel sheet, and at least one of the at least one coating layer is formed by applying the above-described integrated undercoat composition for PCM and curing the coating. Include.

As the undercoat layer includes a matting agent of a specific particle size described above, the surface roughness increases, and as a result, the surface area of the undercoat layer is increased, thereby improving adhesion regardless of the components of the top coat layer in contact with the undercoat layer. Therefore, a top coat component of the art may be applied without limitation as a top coat, for example, it may be a fluorine-based top coat.

As the steel sheet, a metal plate used as a building interior / exterior material in the art may be used without limitation. Non-limiting examples include cold rolled steel (CR), zinc hot dipping steel (GI), electro-zinc steel (EGI), alloy-plate steel (GA), copper sheet or tin-plate steel, hot-dip galvanized steel, Alloyed hot-dip galvanized steel sheet, electro-galvanized steel sheet, hot-dip aluminum-zinc alloy plated steel sheet, and aluminum sheet.

The thickness of the coating layer formed on the steel sheet is not particularly limited, and as an example, a dry coating thickness may be 3 to 25 μm, and another example may be 5 to 15 μm.

The PCM steel sheet according to the present invention may be manufactured according to a conventional method in the art, and may be configured by, for example, coating and drying the above-described PCM coating composition on a metal plate, which is a substrate.

As a coating method of the PCM coating composition, a conventional coating method known in the art may be applied. For example, curtain coating, roll coating, immersion coating, bar coating, and spray coating may be applied. The baking conditions can be appropriately changed according to the conditions such as the width and thickness of the baking sheet, line speed, etc. For example, the peak metal temperature (PMT) can be carried out for 35 to 40 seconds under the conditions of 190 to 230 ° C. If necessary, the metal plate may be pretreated with phosphate or chromate or the like before coating.

PCM steel sheet prepared as described above shows excellent corrosion resistance, chemical resistance and adhesion, it can be usefully used for building interior / exterior materials. However, it is not limited only to the said use.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following examples are only for the understanding of the present invention, and the scope of the present invention is not limited to the examples in any sense.

[ Example  1-2]

According to the composition shown in Table 1 below, using the polyester resin, epoxy resin, curing agent, acid catalyst, pigments, additives, solvents and the like to prepare a coating composition of Example 1-2, respectively. In Table 1 below, the amount of each unit used is in weight percent. Specifications of the raw materials used are shown in Table 2 below.

[ Comparative example  1-4]

According to the composition of Table 1 below, using the polyester resin, epoxy resin, curing agent, pigments, additives, solvents and the like to prepare a coating composition of Comparative Examples 1-4, respectively.

[ Experimental Example Property evaluation]

The coating compositions prepared in Examples 1-2 and Comparative Examples 1-4 were coated with a bottom coat layer, and a polyester top coat and a fluorine top coat were coated on the top coat layer to evaluate their respective properties.

The bottom coat layer is 5 µm (dry coating thickness) and peak metal temperature (PMT) 216 ° C for hot-dip galvanized steel (GI) material, and the top coat layer is 15-20 µm (dry coating thickness) and the maximum steel sheet temperature. (PMT) 224 ° C (polyester top coat) and 241 ° C (fluorine top coat) was prepared by the bar coating (Bar Coating) method (automatic discharge oven conditions: 270 ℃, 25Hz). Each composition of Example 1-2 and Comparative Examples 1-4 was coated under the above curing conditions to prepare test specimens for physical properties, and the test specimens were subjected to physical property tests according to the following physical property measurement methods. The physical property measurement method is shown in Table 3 below. Physical property test results are shown in Table 4 below.

As shown in Table 4, it was confirmed that the coating composition of the present invention exhibits excellent properties in terms of corrosion resistance, processability, and chemical resistance.

Claims (6)

Based on 100% by weight of the paint coating composition, 20-50% by weight of polyester resin, 5-15% by weight of epoxy resin, 3-10% by weight of melamine resin, 0.1-1.0% by weight of acid catalyst, 5-15% by weight of rust preventive pigment, 1-5% by weight of a matting agent and the remaining amount of solvent,
The polyester resin may have a number average molecular weight (Mn) of 6,000-8,000 g / mol, a hydroxyl value (OHv) of 13-23, and a glass transition temperature (Tg) of 20-30 ° C. Undercoat composition comprising a second polyester resin having an average molecular weight (Mn) of 2,000-4,000 g / mol, a hydroxyl value (OHv) of 40-50, and a glass transition temperature (Tg) of 35-45 ° C. . delete delete The undercoat composition of Claim 1 whose mixing ratio (weight ratio) of the said 1st polyester resin and a 2nd polyester resin is 40: 60-60: 40. The undercoat composition of claim 1, wherein the matting agent has an average particle diameter of 5-15 µm. A steel sheet and at least one coating layer formed on the surface of the steel sheet, wherein the lower coating layer is formed from the undercoat composition according to any one of claims 1, 4 or 5. PCM steel plate to be.