KR20220009195A - Water-soluble coating composition for top coat - Google Patents

Abstract

The present invention relates to a water soluble paint composition for top coat which includes an acrylic polyol resin and a polyisocyanate curing agent, wherein the acrylic polyol resin is prepared from a vinyl-based monomer, a (meth)acrylate-based monomer, a negative ionic surfactant, a nonionic surfactant, a polymerization initiator, and a phosphorus compound. According to the present invention, the composition has excellent appearance characteristics, water resistance, weather resistance, hardness, and adhesion.

Description

Water-soluble paint composition for top coat {WATER-SOLUBLE COATING COMPOSITION FOR TOP COAT}

The present invention relates to a water-soluble coating composition for top coating that has excellent appearance properties such as gloss, water resistance, weather resistance, hardness, adhesion, etc., and excellent synthetic stability and anti-foaming properties.

Recently, as the demand for eco-friendly paints such as the regulation of VOCs (volatile organic compounds) in paints is increasing domestically and abroad, the development of water-soluble paints using water as the main solvent rather than oil-based paints is being actively carried out. In particular, in the case of a top coat applied to heavy equipment, ships, railroad vehicles, etc., gloss, appearance, water resistance, solvent resistance, weather resistance, adhesion, corrosion resistance, hardness, etc. must be excellent. To this end, there is a need to develop a water-soluble resin that can be applied to a top coat while having properties similar to those of an existing oil-based paint.

In addition, the water-soluble resin needs excellent stability that does not cause sedimentation during storage as well as the physical properties of the coating film. For this reason, a top coating composition containing a water-soluble acrylic resin that has excellent storage stability and can form a coating film with relatively good durability when dried at room temperature is widely used. For example, the conventional water-soluble acrylic resin is generally prepared by emulsion polymerization using an anionic surfactant as an emulsifier. However, the anionic emulsifier or anionic surfactant causes bubbles to be generated on the surface of the coating film, and there is a problem of reducing the water resistance of the coating film.

As an alternative to this, Korean Patent Registration No. 10-1677427 (Patent Document 1) discloses a method for producing an eco-friendly high-gloss aqueous acrylic resin prepared from an acrylic monomer, an anionic emulsifier, a nonionic emulsifier and a buffer. However, when the water-based acrylic resin of Patent Document 1 is used for a urethane curing type, there is a problem in that the gloss of the prepared coating film is lowered.

Therefore, there is a need for research and development on a water-soluble paint composition for top coats that has excellent appearance characteristics such as gloss, water resistance, weather resistance, hardness, adhesion, etc., and excellent defoaming properties.

Korean Patent Registration No. 10-1677427 (published on July 7, 2016)

Accordingly, the present invention provides a water-soluble paint composition for a top coat excellent in appearance characteristics such as gloss, water resistance, weather resistance, hardness, adhesion, and the like, and excellent defoaming properties.

The present invention comprises an acrylic polyol resin and a polyisocyanate curing agent,

The acrylic polyol resin provides a water-soluble coating composition for top coating, prepared from a vinyl-based monomer, a (meth)acrylate-based monomer, an anionic surfactant, a nonionic surfactant, a polymerization initiator, and a phosphorus-based compound.

The water-soluble paint composition for top coat according to the present invention has excellent defoaming properties despite including an anionic surfactant. In addition, the coating film prepared from the composition is excellent in appearance characteristics such as gloss, water resistance, weather resistance, hardness, adhesion, and the like.

Hereinafter, the present invention will be described in detail.

As used herein, "weight average molecular weight" is measured by a conventional method known in the art, for example, it can be measured by a GPC (gel permeation chromatograph) method. Furthermore, the "glass transition temperature" is measured by a conventional method known in the art, for example, it can be measured by differential scanning calorimetry (DSC). In addition, functional groups such as "acid value" and "hydroxyl value" may be measured by a method well known in the art, for example, by a method of titration.

In addition, in this specification, "(meth)acryl" means "acryl" and/or "methacrylic", and "(meth)acrylate" means "acrylate" and/or "methacrylate" .

The water-soluble paint composition for a top coat according to the present invention includes an acrylic polyol resin and a polyisocyanate curing agent.

Acrylic Polyol Resin

The acrylic polyol resin plays a role in controlling the film-forming properties of the composition and the mechanical and chemical properties of the prepared coating film.

The acrylic polyol resin is prepared from a vinyl-based monomer, a (meth)acrylate-based monomer, an anionic surfactant, a nonionic surfactant, a polymerization initiator, and a phosphorus-based compound. In this case, the method for producing the acrylic polyol resin is not particularly limited as long as it is a temperature and pressure applicable to the production of the acrylic polyol resin, and for example, it may be carried out at 60 to 100 °C, or 60 to 85 °C. When the acrylic polyol is prepared from a composition containing a phosphorus-based compound, there is an effect of delaying curing of urethane and improving rust prevention properties.

<Vinyl-based monomer and (meth)acrylate-based monomer>

The vinyl-based monomer and (meth)acrylate-based monomer serve to impart durability and adhesion to the coating film.

The type of the vinyl monomer is not particularly limited, but for example, styrene, methylstyrene, dimethylstyrene, fluorostyrene, ethoxystyrene, methoxystyrene, phenylene vinyl ketone, vinyl t-butyl benzoate, vinyl cyclohexano At least one selected from ester, vinyl acetate, vinyl pyrrolidone, vinyl chloride, vinyl alcohol, acetoxystyrene, t-butylstyrene and vinyltoluene may be used.

The (meth)acrylate-based monomer may include at least one selected from the group consisting of a hydroxyl group-free (meth)acrylate monomer and a hydroxyl group-containing (meth)acrylate monomer.

The hydroxyl group-free (meth) acrylate monomer is, for example, (meth) acrylic acid, methyl (meth) acrylic acid, (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, propyl ( Meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate , heptyl (meth) acrylate, isooctyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isodecyl (meth) acrylate, decyl (meth) acrylate, dodecyl It may include at least one selected from the group consisting of (meth)acrylate, isobornyl (meth)acrylate, and lauryl (meth)acrylate.

The hydroxyl group-containing (meth)acrylate monomer may be, for example, a hydroxyalkyl-containing (meth)acrylate, specifically, 2-hydroxymethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate ) may include at least one selected from the group consisting of acrylate, 2-hydroxypropyl (meth)acrylate and 2-hydroxybutyl (meth)acrylate.

100 to 300 parts by weight, or 130 to 250 parts by weight, or 160 to 190 parts by weight of the (meth)acrylate-based monomer based on 100 parts by weight of the vinyl-based monomer may be included. When the (meth)acrylate-based monomer is less than the above range, water resistance may decrease, and when it exceeds the above range, impact resistance may decrease.

For example, 100 to 200 parts by weight or 120 to 170 parts by weight of a hydroxyl group-free (meth)acrylate monomer, and 1 to 100 parts by weight or 15 to 45 parts by weight of a hydroxyl group based on 100 parts by weight of the vinyl monomer. group containing (meth)acrylate monomers.

When the content of the hydroxyl group-free (meth)acrylate monomer is less than the above range, water resistance and corrosion resistance may be reduced, and when it exceeds the above range, impact resistance may be reduced. In addition, when the content of the hydroxyl group-containing (meth)acrylate monomer exceeds the above range, the appearance characteristics, impact resistance, etc. of the coating film may be insufficient.

<Anionic surfactant>

The anionic surfactant serves to emulsify the monomer.

In addition, the anionic surfactant may include sulfate or sulfonate. For example, the anionic surfactants include alkylarylether sulfates and sulfonates; alkylarylpolyether sulfates and sulfonates; alkyl sulfates and sulfonates; alkylaryl sulfates and sulfonates; alkylether sulfates and sulfonates; and alkyl polyether sulfates and sulfonates.

At this time, the alkylarylpolyether sulfate and sulfonate may include, for example, alkylarylpoly(ethylene oxide) sulfate and sulfonate, and Rohm and Haas' "TRITON X200" as a commercially available product ", Adekasa "SR-10", etc. are mentioned. In addition, examples of the alkyl sulfate and sulfonate include sodium lauryl sulfate, ammonium lauryl sulfate, triethanolamine lauryl sulfate, and sodium hexadecyl sulfate. In addition, examples of the alkylaryl sulfate and sulfonate include sodium dodecylbenzene sulfate and sodium dodecylbenzene sulfonate. In addition, the alkyl ether sulfates and sulfonates include, for example, ammonium lauryl ether sulfate, and the alkyl polyether sulfates and sulfonates include, for example, alkyl poly (ethylene oxide) sulfates and sulfonates. can

The anionic surfactant may be included in the composition in an amount of 1 to 20 parts by weight, or 5 to 15 parts by weight based on 100 parts by weight of the vinyl-based monomer. When the content of the anionic surfactant is less than the above range, a problem occurs in that water dispersion stability is lowered, and when it exceeds the above range, problems in defoaming properties and water resistance may occur.

<Non-ionic surfactant>

The nonionic surfactant allows monomers to be polymerized into a stabilized homogeneous phase.

In addition, the nonionic surfactant may have a Hydrophile-Lipophile Balance (HLB) value of 10 to 30, or 10 to 18. When the HLB value of the nonionic surfactant is less than the above range, a problem of lowering water dispersion stability occurs, and when it exceeds the above range, a problem of lowering water resistance may occur.

The nonionic surfactant is, for example, polyethylene oxide alkyl ether, polyethylene oxide alkylphenyl ether, sorbitan fatty acid ester, polyoxyethylene fatty acid amide, N,N-bis-2-hydroxyalkylamine, glycerin fatty acid monoester type, methyl ester ethoxylate type, pentathiol fatty acid ester type, etc. are mentioned.

In addition, the nonionic surfactant may be included in the composition in an amount of 0.5 to 10 parts by weight, or 2 to 6 parts by weight, based on 100 parts by weight of the vinyl monomer. When the content of the nonionic surfactant is less than the above range, water dispersion stability and appearance may be deteriorated, and if it exceeds the above range, water dispersion stability may be deteriorated.

The composition may include the anionic surfactant and the nonionic surfactant in a weight ratio of 1 to 7: 1, or 1 to 3.5: 1 by weight. When the weight ratio is less than the above range, that is, when it contains a small amount of anionic surfactant compared to the nonionic surfactant, a problem occurs in water dispersion stability, and when it exceeds the above range, that is, excessive anionicity compared to the nonionic surfactant When a surfactant is included, there may be problems in that water resistance is lowered and appearance is lowered.

<Polymerization Initiator>

The polymerization initiator is a component that initiates emulsion polymerization, and is not particularly limited as long as it is a substance that is decomposed by heat to generate radicals. For example, the polymerization initiator may include ammonium persulfate, potassium persulfate, sodium hydrosulfite, sodium persulfate, sodium hydrogen sulfate, or a combination thereof.

The polymerization initiator may be included in the composition in an amount of 0.1 to 5 parts by weight, or 1.0 to 2.0 parts by weight based on 100 parts by weight of the vinyl-based monomer. If the content of the polymerization initiator is less than the above range, the polymerization reaction may not occur properly, and if it exceeds the above range, unreacted polymerization initiator may remain in the acrylic polyol resin and a problem that the polymerization degree is lowered may occur.

<Phosphorus compound>

The phosphorus-based compound serves to delay curing of the urethane and improve rust prevention.

In this case, as the phosphorus-based compound, a liquid-type type having a high boiling point and environment-friendly environment while minimizing a decrease in the glass transition temperature of the coating film may be used. For example, it may include at least one selected from the group consisting of tris(2,4-di-tert-butylphenyl) phosphate, phosphoric acid, tributyl phosphate, and triphenyl phosphate.

In addition, the phosphorus-based compound may be included in the composition in an amount of 0.5 to 10 parts by weight, or 1.0 to 3.0 parts by weight based on 100 parts by weight of the vinyl-based monomer. If the content of the phosphorus-based compound is less than the above range, the effect of improving the rust prevention properties of the coating film, which is an effect due to the phosphorus-based compound, is insufficient.

<Additives>

The acrylic polyol resin may be prepared from the components and additives described above. In this case, the additive is not particularly limited as long as it is generally applicable when preparing the acrylic polyol resin, and for example, a solvent, a reducing agent, a chain transfer agent, a neutralizing agent, and the like may be mentioned.

The solvent may be a dispersion medium, for example, deionized water. In this case, the solvent may be used in an amount of 200 to 600 parts by weight, or 350 to 480 parts by weight based on 100 parts by weight of the vinyl monomer.

The reducing agent is a component that improves the polymerization rate of the acrylic polyol resin, and includes, for example, reducing organic compounds such as ascorbic acid, citric acid, tartaric acid, and glucose; inorganic compounds such as sodium thiosulfate, sodium metasulfite, sodium bisulfite, and sodium metabisulfite; and the like, but is not limited thereto.

The reducing agent may be used in an amount of 0.01 to 2 parts by weight, or 0.01 to 1 parts by weight based on 100 parts by weight of the vinyl monomer.

The chain transfer agent is a component for controlling the molecular weight of the acrylic polyol resin, and may include, for example, an alkyl mercaptan having 6 to 18 carbon atoms or 7 to 16 carbon atoms. Specifically, the chain transfer agent may be at least one selected from the group consisting of n-dodecyl mercaptan, tert-dodecyl mercaptan, octyl mercaptan, tetradecyl mercaptan, hexadecyl mercaptan and ethylhexyl mercaptan. However, the present invention is not limited thereto.

The chain transfer agent may be used in an amount of 0.1 to 5.0 parts by weight, or 1.5 to 3.0 parts by weight based on 100 parts by weight of the vinyl-based monomer.

The neutralizing agent is a component that adjusts the pH of the acrylic polyol resin, for example, an inorganic base such as ammonia, sodium hydroxide (NaOH), potassium hydroxide (KOH), lithium hydroxide (LiOH), and dimethylethanolamine, triethylamine and organic bases such as primary, secondary, and tertiary amines, and aqueous solutions thereof.

The neutralizing agent may be used in an amount of 0.01 to 3 parts by weight, or 0.5 to 2.0 parts by weight based on 100 parts by weight of the vinyl monomer.

The acrylic polyol resin may have a hydroxyl value (OHv) of 40 to 120 mgKOH/g, or 60 to 100 mgKOH/g. When the hydroxyl value of the acrylic polyol resin is within the above range, there is an effect of improving the weather resistance of the coating film. In addition, when the hydroxyl value of the acrylic polyol resin is less than the above range, the coating film formation by the crosslinking reaction with the curing agent is insufficient, and the hardness and water resistance of the coating film are reduced. Shortage problems may arise.

In addition, the acrylic polyol resin may have an acid value (Av) of 5 to 30 mgKOH/g, or 5 to 20 mgKOH/g. When the acid value of the acrylic polyol resin is within the above range, water dispersibility and storage stability of the coating composition are improved, and water resistance is improved. In addition, when the acid value of the acrylic polyol resin is less than the above range, the water dispersion stability of the resin may be deteriorated.

The acrylic polyol resin may have a glass transition temperature (Tg) of 20 to 50 °C, or 25 to 40 °C. When the glass transition temperature of the acrylic polyol resin is within the above range, coating film formation and defoaming properties of the composition, and gloss properties of the coating film are improved. In addition, when the glass transition temperature of the acrylic polywool resin is less than the above range, there is a problem in that the impact resistance of the prepared coating film is insufficient, and when it exceeds the above range, the appearance characteristics and hardness of the coating film may be insufficient.

In addition, the acrylic polyol resin may have a solid content (NV) of 30 to 60% by weight, or 35 to 50% by weight, based on the total weight. When the solid content of the acrylic polyol resin is within the above range, storage stability of the resin and storage stability of the coating composition may be improved, and workability may be excellent. In addition, when the solid content of the acrylic polyol resin is less than the above range, the viscosity is too low and the workability of the coating composition including the same is insufficient. Stability is poor, dispersion stability is deteriorated, and agglomeration may occur over time.

The weight average molecular weight (Mw) of the acrylic polyol resin may be 3,000 to 30,000 g/mol, or 5,000 to 25,000 g/mol. When the weight average molecular weight of the acrylic polyol resin is within the above range, the hardness of the prepared coating film may be excellent. In addition, when the weight average molecular weight of the acrylic polyol resin is less than the above range, the water resistance of the prepared coating film is insufficient. There may be a problem in that it is difficult to manufacture a coating film having the

In addition, the acrylic polyol resin may have a pH of 5 to 9, or 6 to 8. In this case, the pH of the acrylic polyol resin can be adjusted by using the neutralizing agent as described above.

The acrylic polyol resin may be included in the composition in an amount of 30 to 60 parts by weight, 35 to 55 parts by weight, or 40 to 50 parts by weight based on 5 to 25 parts by weight of the polyisocyanate curing agent. When the content of the acrylic polyol resin is within the above range, there is an effect of improving adhesion and impact resistance of the coating film. In addition, when the content of the acrylic polyol resin is less than the above range, adhesion and durability of the coating film may be deteriorated.

polyisocyanate curing agent

The polyisocyanate curing agent serves to cure the paint composition by crosslinking reaction with the acrylic polyol resin.

The polyisocyanate curing agent may be directly synthesized according to a known method, or a commercially available product may be used. For example, the polyisocyanate curing agent may be a polyfunctional compound including two or more isocyanate groups in one molecule.

In addition, the polyisocyanate curing agent may have a content of unreacted NCO groups (NCO%) of 10 to 30% by weight, 13 to 25% by weight, or 18 to 22% by weight based on the total weight of the curing agent. When the NCO% of the polyisocyanate curing agent is within the above range, there is an effect of improving the weather resistance of the prepared coating film and improving the stability of the coating composition after water dispersion. In addition, when the NCO% of the polyisocyanate curing agent exceeds the above range, the water dispersion stability of the coating composition is lowered, and when it is less than the above range, water resistance and corrosion resistance of the prepared coating film may be insufficient.

The polyisocyanate curing agent may have a weight average molecular weight (Mw) of 500 to 3,000 g/mol, 1,000 to 3,000 g/mol, or 1,000 to 2,000 g/mol. When the weight average molecular weight of the polyisocyanate curing agent is within the above range, the composition has excellent stability in water dispersion and stable reactivity with the acrylic polyol resin, thereby improving the hardness and gloss of the coating film. In addition, when the Mw of the polyisocyanate curing agent exceeds the above range, the water dispersion stability of the coating composition is lowered, and when it is less than the above range, a problem of insufficient water dispersion stability of the coating composition may occur.

In addition, the polyisocyanate curing agent may be diluted with a solvent, stored in a separate container, and sufficiently stirred immediately before use. In this case, the solvent is not particularly limited as long as it is a conventional solvent used in the coating composition.

The polyisocyanate curing agent may be included in the composition in an amount of 5 to 25 parts by weight, 10 to 20 parts by weight, or 13 to 17 parts by weight based on 30 to 60 parts by weight of the acrylic polyol resin. When the content of the polyisocyanate curing agent is within the above range, there is an effect of improving the water resistance of the coating film and improving the stability of the coating composition after water dispersion. In addition, when the content of the polyisocyanate curing agent is less than the above range, there is a problem of lowering the water resistance of the coating film and stability after water dispersion of the coating composition, and when it exceeds the above range, the hardness of the coating film may be reduced.

The water-soluble paint composition for the top coat may further include a solvent and an additive.

solvent

The solvent maintains the thickness of the prepared coating film and controls the viscosity of the coating composition to improve workability.

The solvent may include at least one selected from the group consisting of an organic solvent and water. For example, the solvent may include a mixture of water and an organic solvent, but may be appropriately selected and used according to the characteristics or volatilization rate of the resin in the composition.

The water may include deionized water (DIW) and distilled water, and serves to reduce the generation of volatile organic compounds (VOCs) in the composition.

The organic solvent is not particularly limited as long as it is a solvent compatible with water, and for example, isopropanol, propylene glycol, normal propyl ether, propylene glycol normal butyl ether, dipropylene glycol methyl ether, dipropylene glycol normal butyl ether, dipropylene glycol basic ether, propanediol diacetate, and mixtures thereof.

The solvent may be included in the composition in an amount of 2 to 25 parts by weight, or 7 to 18 parts by weight based on 30 to 60 parts by weight of the acrylic polyol resin. For example, the solvent may include 1 to 10 parts by weight or 2 to 6 parts by weight of the organic solvent, and 1 to 15 parts by weight or 5 to 12 parts by weight of water based on 30 to 60 parts by weight of the acrylic polyol resin.

When the solvent content is within the above range, there is an effect of improving the storage stability of the composition, and when the organic solvent content is within the above range, it is possible to prevent the drying problem of the composition. In addition, when the content of the organic solvent is less than the above range, cracks may occur in the coating film, and when the content of the organic solvent exceeds the above range, a large problem may occur in the VOC content of the coating composition. In addition, when the water content is less than the above range, the viscosity of the coating composition is high and workability is poor.

additive

The additive is not particularly limited as long as it is an additive that can be usually applied to the top coat composition, and for example, a pigment, a surface control agent, a dispersant, a wettability control agent, a rheology control agent, an antifoaming agent, and the like. At this time, each component of the additive is not particularly limited as long as it is used in the coating composition.

2-component

The water-soluble paint composition for top coat may be a two-component paint composition including a main part and a curing agent part. Specifically, the main part and the curing agent part may be stored in separate containers and mixed immediately before use.

In addition, the main part may include the acrylic polyol resin, a solvent, and an additive, and the curing agent part may include the polyisocyanate curing agent and a solvent. Specifically, the main part may include an acrylic polyol resin, a solvent, a pigment, a surface conditioning agent, a dispersing agent, a wettability regulator, a rheology regulator, and an antifoaming agent, and the curing agent part may include the polyisocyanate curing agent and a solvent.

The water-soluble paint composition for the top coat may have a viscosity of 10 to 30 seconds, or 15 to 25 seconds based on Jancup No. 3 at 25°C.

The coating composition according to the present invention as described above is water-soluble and has a low VOC content, so it is eco-friendly, and has excellent defoaming properties despite including an anionic surfactant. In addition, the coating film prepared from the composition is excellent in appearance characteristics such as gloss, water resistance, weather resistance, hardness, adhesion, and the like.

Hereinafter, the present invention will be described in more detail through examples. However, these examples are only for helping the understanding of the present invention, and the scope of the present invention is not limited to these examples in any sense.

[Example] 1

Preparation Example 1. Preparation of acrylic polyol resin-1

In a reactor equipped with a stirrer, thermometer and condenser, 43 g of deionized water, 1.6 g of SR-10 (manufactured by ADEKA Corporation) as an anionic surfactant, and 0.5 g of ER-10 (manufactured by ADEKA Corporation, HLB value: 14) as a nonionic surfactant g, and the temperature was raised to 80°C.

13.9 g of styrene (SM), 0.7 g of methacrylic acid, 9.8 g of methyl methacrylate, 9.4 g of 2-ethylhexyl acrylate, 5.5 g of 2-hydroxylethyl methacrylate (2-HEMA), and n as a chain transfer agent - 0.3 g of dodecyl mercaptan was mixed to prepare a mixture. In addition, an initiator was prepared by mixing 12 g of deionized water and 0.2 g of ammonium persulfate.

Then, 1.285 g of the mixture and 2.44 g of the initiator were put into a reactor and stirred for 20 minutes to prepare a seed emulsion resin. Thereafter, the remaining amount of the mixture and the remaining amount of the initiator were added to the reactor for 4 hours, and then maintained at 80° C. for 1 hour to prepare an emulsion resin in the form of a stabilized uniform phase. After cooling to 40 ° C, 2.6 g of deionized water, 0.2 g of ammonia water, and 0.3 g of phosphoric acid were added and stirred for 1 hour to prepare an emulsion type acrylic polyol resin-1 (solid content: 41 wt%, average particle diameter: 80 nm) did

Preparation Examples 2 to 12. Preparation of acrylic polyol resin-2 to 12

An acrylic polyol resin was prepared by mixing each component with a composition as shown in Tables 1 and 2 below.

Preparation Example 1 Preparation 2 Preparation 3 Preparation 4 Preparation 5 Preparation 6 Preparation 7 deionized water 43 43 41.7 41.7 40.6 41.8 43.5 anionic surfactant SR-10 1.6 1.6 1.6 0.5 4 1.6 1.6 nonionic surfactant ER10 0.5 0.5 0.5 0.5 0.5 0.2 0.5 deionized water 12 12 12 12 12 12 12 polymerization initiator Ammonium Persulfate 0.2 0.2 0.2 0.2 0.2 0.2 0.2 vinyl monomer styrene 13.9 13.9 13.9 13.9 13.9 15.4 13.9 (meth)acrylate-based monomer methacrylic acid 0.7 0.7 0.7 0.7 0.7 0.7 0.7 methyl methacrylate 9.8 9.8 12.3 4.6 9.8 9.8 14.5 2-ethylhexyl acrylate 9.4 9.4 10 8.5 9.4 9.4 10.2 2-hydroxyl ethyl methacrylate 5.5 5.5 2.8 12 5.5 5.5 - chain transfer agent n-dodecyl mercaptan 0.3 0.3 0.3 0.3 0.3 0.3 - deionized water 2.6 2.6 3.5 4.6 2.6 2.6 2.6 corrector ammonia 0.2 0.2 0.2 0.2 0.2 0.2 - Phosphorus compound phosphoric acid 0.3 - 0.3 0.3 0.3 0.3 0.3 tributyl phosphate - 0.3 - - - - - total 100 100 100 100 100 100 100 Acrylic Polyol Resin Tg(℃) 30 30 30 30 30 60 30 OHv (mgKOH/g) 60 60 60 130 60 60 60 Av(mgKOH/g) 12 12 12 12 12 12 12 NV (wt%) 41 41 42 35 45 42 41 Mw (g/mol) 20,000 19,000 19,000 23,000 20,000 20,000 19,000 Particle average diameter (nm) 80 80 60 150 60 100 80

Preparation 8 Preparation 9 Preparation 10 Preparation 11 Preparation 12 deionized water 43 43 43 43 43 anionic
Surfactants SR-10 1.55 1.6 1.6 1.6 - nonionic
Surfactants ER10 0.5 0.5 0.5 - One deionized water 12 12 12 12 12 polymerization initiator Ammonium Persulfate 0.2 0.2 0.2 0.2 0.2 vinyl monomer styrene 13.9 13.9 13.9 13.9 13.9 (meth)acrylate-based monomer methacrylic acid 0.7 0.7 0.7 0.7 0.7 methyl methacrylate 9.8 9.8 9.8 9.8 9.8 2-ethylhexyl acrylate 9.4 9.4 9.4 9.4 9.4 hydroxyl ethyl methacrylate 5.5 5.5 5.5 5.5 5.5 chain transfer agent n-dodecyl mercaptan 0.3 0.3 0.3 0.3 0.3 deionized water 2.8 2.5 2.9 3.1 3.7 corrector ammonia 0.2 0.2 0.2 0.2 0.2 Phosphorus compound phosphoric acid 0.15 0.4 - 0.3 0.3 tributyl phosphate - - - - - total 100 100 100 100 100 Acrylic Polyol Resin Tg(℃) 30 27 30 30 30 OHv (mgKOH/g) 60 60 60 60 60 Av(mgKOH/g) 12 12 12 12 12 NV (wt%) 42 42 41 41 41 Mw (g/mol) 20,000 22,000 19,000 19,000 19,000 Particle average diameter (nm) 80 80 80 80 80

Examples 1 to 9 and Comparative Examples 1 to 3. Preparation of water-soluble paint composition

An aqueous coating composition was prepared by mixing each component in the composition as shown in Tables 3 and 4 below.

Ingredients (parts by weight) Example One 2 3 4 5 6 7 8 9 subject part water 8.37 8.67 8.47 8.37 8.37 8.37 8.37 8.37 8.37 organic solvent 4.3 4.3 4.3 4.3 4.3 4.3 4.3 4.3 4.3 pigment 21.3 21.3 21.3 21.3 21.3 21.3 21.3 21.3 21.3 Acrylic polyol resin-1 (Preparation Example 1) 45.2 - - - - - - - - Acrylic polyol resin-2 (Preparation Example 2) - 45.2 - - - - - - - Acrylic polyol resin-3 (Preparation Example 3) - - 45.2 - - - - - - Acrylic polyol resin-4 (Preparation Example 4) - - - 45.2 - - - - - Acrylic polyol resin-5 (Preparation Example 5) - - - - 45.2 - - - - Acrylic polyol resin-6 (Preparation Example 6) - - - - - 45.2 - - - Acrylic polyol resin-7 (Preparation Example 7) - - - - - - 45.2 - - Acrylic polyol resin-8 (Preparation Example 8) - - - - - - - 45.2 - Acrylic polyol resin-9 (Preparation Example 9) - - - - - - - 45.2 surface conditioning agent 1.3 One 1.2 1.3 1.3 1.3 1.3 1.3 1.3 dispersant 3.5 3.5 3.5 3.5 3.5 3.5 3.5 3.5 3.5 wetting agent 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 Rheology modifiers 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 antifoam 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 polyisocyanate curing agent 15 15 15 15 15 15 15 15 15 total amount 100 100 100 100 100 100 100 100 100

Ingredients (parts by weight) comparative example One 2 3 subject part water 8.37 8.37 8.37 organic solvent 4.3 4.3 4.3 pigment 21.3 21.3 21.3 Acrylic polyol resin-10 (Preparation Example 10) 45.2 - - Acrylic polyol resin-11 (Preparation Example 11) - 45.2 - Acrylic polyol resin-12 (Preparation Example 12) - - 45.2 surface conditioning agent 1.3 1.3 1.3 dispersant 3.5 3.5 3.5 wetting agent 0.4 0.4 0.4 Rheology modifiers 0.23 0.23 0.23 antifoam 0.4 0.4 0.4 polyisocyanate curing agent 15 15 15 total amount 100 100 100

Hereinafter, manufacturers and product names of each component used in Examples and Comparative Examples are shown in Table 5 below.

Chemical name or physical property Manufacturer and product name solvent Dibasic ester - pigment titanium dioxide Manufacturer: CHEMOURS, product name: R-902+ surface conditioning agent - Manufacturer: BYK, Product Name: BYKETOL AQ dispersant - Manufacturer: BYK, Product name: BYK-190 wetting agent - Manufacturer: BASF, product name: WE3323 Rheology modifiers - Manufacturer: DOW, Product Name: RM12W antifoam - Manufacturer: BASF, product name: ST2400 polyisocyanate curing agent - Manufacturer: Covestro,
Product Name: Bayhydur® XP 2655

Test Example: Characteristic Evaluation

The coating compositions of Examples and Comparative Examples were coated, dried at room temperature for 20 minutes, and cured at 60° C. for 4 hours to prepare a specimen coating film. Thereafter, the physical properties of the coating composition and the coating film of the specimen were measured in the following manner, and the results are shown in Tables 6 and 7.

(1) Viscosity

The viscosity at 25° C. was measured using ZahnCup No. 3 to measure the viscosity of the coating composition.

(2) Appearance

The appearance characteristics of the specimen coating film were evaluated. Excellent (◎) when there were no pinholes and cratering on the surface, Good (○) when 1 to 5 pinholes and cratering occurred per specimen, and more than 5 and less than 10 Normal (Δ), when it occurred more than 10, it was evaluated as bad (×).

(3) Gloss and gloss retention

The 60° gloss of the surface of the coating film was measured with a gloss meter for the specimen coating film, and when the measured gloss (hereinafter, referred to as "initial gloss") was 80% or more, it was considered excellent, and when it was 70% or more, the gloss was judged to be good.

After the specimen coating film was stored at room temperature for 5 hours, the 60° gloss of the coating film surface (hereinafter, referred to as “glossy after storage”) was measured with a gloss meter, and the gloss retention rate was calculated based on the initial gloss by Equation 1 below. When it was 90% or more, it was judged as excellent, and when it was 70% or more, the gloss was judged to be good.

[Equation 1]

(4) hardness

The pencil hardness of the coating film of the specimen was measured using a Mitsubishi pencil. Specifically, 3B, 2B, B, HB, F, H, 2H, and 3H each of the pencils were used to measure the maximum hardness that does not damage the coating film of the specimen (3B, 2B, B, HB, F, H, 2H). , 3H: inferior ⇔ excellent).

(5) Adhesiveness

According to the ASTM D3359 tape adhesion test method, 25 squares of 2 mm × 2 mm (width × length) are formed on the surface of the specimen coating film using a cutter knife, and then the square is peeled off using a tape to ensure adhesion. was measured.

At this time, 5B if the 25 squares are 100% completely attached, 4B if the remaining squares are 95% or more but less than 100%, 3B if 85% or more and less than 95%, 2B if 65% or more and less than 85%, 35% or more and less than 65% Case 1B and less than 35% were evaluated as 0B.

(6) Defoaming

After painting, the time for bubbles to disappear from the surface of the coating film of the specimen was measured. If the time is less than 5 seconds, excellent (◎), between 5 and 30 seconds good (○), when it exceeds 30 seconds and less than 60 seconds, it is normal (Δ), In the case of 60 seconds or more, it was evaluated as bad (×).

(7) Impact resistance

According to ASTM D2794, after dropping a 500 g weight onto the coating film of the specimen from a height of 10 inches or more, the surface of the coating film was observed to measure the maximum height at which uniformity and peeling did not occur in the coating film, and the impact resistance was evaluated.

(8) water resistance

The coating composition was applied to a glass plate of 15 cm × 30 cm (width × length) in a thickness of 10 μm and then cured at 40° C. for 20 minutes. Then, it was immersed in water for 24 hours, and the glass plate was taken out to check the degree of discoloration of the coating film.

At this time, excellent (◎) when there is no discoloration of the coating film, good (○) when slight discoloration occurs and no floatation occurs, good (○) when slight discoloration occurs and slight lifting occurs due to lack of water resistance Normal (△), lifting When the coating film was peeled off due to severe severity, it was evaluated as bad (X).

Example One 2 3 4 5 6 7 8 9 Viscosity 21 seconds 21 seconds 22 seconds 22 seconds 22 seconds 22 seconds 21 seconds 22 seconds 22 seconds Exterior ◎ ◎ ◎ ◎ ○ ◎ ◎ ◎ ◎ Film thickness (㎛) 40 37 38 39 39 38 39 37 37 gloss retention 95% 95% 80% 80% 75% 80% 95% 90% 90% initial gloss 84% 85% 83% 80% 82% 81% 80% 82% 83% Hardness 2H 2H 2H H 2H H H 2H 2H adherence 4B 4B 4B 4B 4B 4B 4B 4B 4B Impact resistance (inch) 27 29 28 29 28 29 30 28 29 water resistance ◎ ◎ ◎ ○ ◎ ○ ○ ◎ ◎ defoaming ◎ ◎ ◎ ◎ ◎ ○ ○ ◎ ◎

comparative example One 2 3 Viscosity 22 seconds 10 seconds 21 seconds Exterior ○ ○ X Film thickness (㎛) 20 39 38 gloss retention 50% 40% 30% initial gloss 72% 74% 72% Hardness 2B HB HB adherence 4B 4B 4B Impact resistance (inch) 33 35 33 water resistance ○ X ○ defoaming ○ X ○

As shown in Table 6, the coating composition of Examples has an appropriate viscosity and thus excellent coating workability, and the coating film prepared therefrom has excellent appearance, gloss retention, initial gloss, hardness, adhesion, impact resistance, water resistance and defoaming properties. It was excellent.

On the other hand, as shown in Table 7, Comparative Example 1 including the acrylic polyol-10 without the phosphorus compound had a thin coating film, and lacked gloss retention and hardness.

In addition, Comparative Example 2 containing the acrylic polyol resin-11 without a nonionic surfactant had a low viscosity, making it difficult to work, and lacked gloss retention, water resistance and defoaming properties.

In addition, Comparative Example 3 including the acrylic polyol resin-12 without an anionic surfactant was poor in appearance characteristics due to the occurrence of pinholes, and the gloss retention was also remarkably insufficient.

Claims (6)

An acrylic polyol resin and a polyisocyanate curing agent,
The acrylic polyol resin is prepared from a vinyl-based monomer, a (meth)acrylate-based monomer, an anionic surfactant, a nonionic surfactant, a polymerization initiator, and a phosphorus-based compound, a water-soluble paint composition for top coating. The method according to claim 1,
The acrylic polyol resin has a hydroxyl value of 40 to 120 mgKOH/g, an acid value of 5 to 30 mgKOH/g, and a glass transition temperature of 20 to 50° C., a water-soluble coating composition for top coating. The method according to claim 1,
The phosphorus-based compound is tris (2,4-di-tert-butylphenyl) phosphate, phosphoric acid, tributyl phosphate, and water-soluble paint composition for a top coat comprising at least one selected from the group consisting of triphenyl phosphate. The method according to claim 1,
The acrylic polyol resin comprises 100 parts by weight of a vinyl monomer, 100 to 300 parts by weight of a (meth)acrylate-based monomer, 1 to 20 parts by weight of an anionic surfactant, 0.5 to 10 parts by weight of a nonionic surfactant, 0.1 to 5 parts by weight A water-soluble paint composition for a top coat, prepared from a polymerization initiator and 0.5 to 10 parts by weight of a phosphorus compound. The method according to claim 1,
A water-soluble paint composition for top coating, comprising 30 to 60 parts by weight of an acrylic polyol resin and 5 to 25 parts by weight of a polyisocyanate curing agent. The method according to claim 1,
When the coating film prepared from the composition has an average thickness of 35 to 40 μm, the pencil hardness is H or more, and the impact resistance measured using a 500 g weight by the method described in ASTM D 2794 is 20 inches or more, and is calculated by the following Equation 1 A water-soluble paint composition for a top coat, having a gloss retention of 80% or more.
[Equation 1]

In Equation 1 above,
The initial gloss is the 60° gloss of the coating film after painting,
The gloss after storage is 60° gloss after 5 hours of storage at room temperature after painting.