KR20240063565A - Water-soluble top coating composition having high-weather resistance - Google Patents

Abstract

The present invention relates to a subject matter comprising a first acrylic resin and a second acrylic resin; and a curing agent comprising an epoxy-acrylic resin, wherein the second acrylic resin is an acid-modified acrylic resin.

Description

High weather resistance water-based topcoat composition {WATER-SOLUBLE TOP COATING COMPOSITION HAVING HIGH-WEATHER RESISTANCE}

The present invention relates to a water-based topcoat composition that has excellent corrosion resistance, weather resistance, and mechanical properties, and is capable of forming a coating film with an attractive appearance.

In response to strengthening environmental regulations in the Chinese market, which accounts for more than 95% of global container production, paints used inside general dry container production lines have been converted to water-soluble paints since April 2017. In addition, starting from the second half of 2021, in order to reduce volatile organic compounds (VOCs) in the refrigerated container production process, the use of conventional oil-based paints will be stopped in all processes except pretreatment, and low-VOCs eco-friendly paints, including water-based paints, will be applied.

Specifically, water-based coating specifications for refrigerated containers typically include applying zinc metallizing or an epoxy-based zinc base coat only to steel parts such as frames, and then applying an epoxy-based middle coat and an acrylic or urethane-based top coat to the entire area. At this time, by applying an acrylic or urethane-based paint with excellent weather resistance as a top coat, changes in color and gloss can be minimized when the paint film is exposed to external environments such as sunlight. For example, Korean Patent No. 978606 (Patent Document 1) discloses an acrylic emulsion resin made by copolymerizing acrylic and styrene monomers; A self-crosslinking polymer organic binder containing hydroxyl groups and carboxyl groups; Non-toxic rust-prevention pigment made of trimethylated silica; and a silicone-based water repellent; a water-based rust preventive paint composition comprising a.

On the other hand, in order to improve the mechanical properties of the coating film to preserve the loaded cargo more safely and to strengthen the rust prevention of the coating film, an epoxy-based topcoat is sometimes applied. In this case, as no water-based product exists to date, an oil-based epoxy-based topcoat is used. I'm doing it. Therefore, there is a need for research and development on an eco-friendly water-based epoxy topcoat that can form a film of comparable quality to conventional oil-based paints.

Korean Patent No. 978606 (Publication Date: 2010.8.23.)

Accordingly, the present invention provides a water-based topcoat composition that is excellent in strength, adhesion, wear resistance, corrosion resistance, and weather resistance and can form a coating film with an attractive appearance.

The present invention relates to a subject matter comprising a first acrylic resin and a second acrylic resin; and

A curing agent containing an epoxy-acrylic resin;

The second acrylic resin provides an aqueous topcoat composition wherein the acid-modified acrylic resin is an acid-modified acrylic resin.

The water-based topcoat composition according to the present invention contains an epoxy-acrylic hybrid resin, so it has excellent mechanical properties such as strength, adhesion, and abrasion resistance of the coating film, and contains a quick-drying acrylic resin, so the composition has excellent drying properties. In addition, the water-based topcoat composition can produce a coating film that has the advantages of an epoxy paint, such as corrosion resistance and mechanical properties, while also having a beautiful appearance and weather resistance as an external coating film.

Hereinafter, the present invention will be described in detail.

“Weight average molecular weight” and “number average molecular weight” used in this specification are measured by common methods known in the art, and can be measured, for example, by GPC (gel permeation chromatograph) method.

In the present invention, the “glass transition temperature” of the resin is measured by a common method known in the art, and can be measured, for example, by differential scanning calorimetry (DSC).

In addition, equivalent weights such as “epoxy equivalent weight” and “active hydrogen equivalent weight” can be measured by methods well known in the art, and can represent values measured by, for example, titration.

Furthermore, the “average diameter” may be the diameter of 50% of the cumulative distribution (D ₅₀ ) in the particle size distribution map measured using a particle size analyzer (PSA).

The water-based topcoat composition according to the present invention includes a base comprising a first acrylic resin and a second acrylic resin; and a curing agent containing an epoxy-acrylic resin. For example, the water-based topcoat composition according to the present invention may be a two-component paint composition containing a base material and a curing agent.

<topic>

The subject matter includes a first acrylic resin and a second acrylic resin.

The first acrylic resin is the main resin that plays a key role in realizing the physical properties of the paint, and contains an acrylic group, thereby improving the weather resistance of the paint composition.

In addition, the second acrylic resin is an acid-modified acrylic resin, and the epoxy group of the epoxy-acrylic resin applied as a curing agent reacts with the acidic functional group of the second acrylic resin to form an epoxy coating film, and the first acrylic resin is a one-component acrylic resin. It has the effect of improving the mechanical properties such as hardness and wear resistance of the coating film compared to the coating film manufactured by applying only the coating film.

Due to the chemical structure of amines or amides, which are commonly used as curing agents for epoxy resins, having a chromophore, the coating film containing them may be discolored when exposed to the external environment and exposed to moisture or sunlight. On the other hand, when the first acrylic resin and the second acrylic resin, which is an acid-modified acrylic resin, are used together as in the present invention, the weather resistance of the paint composition can be improved and the physical properties of an epoxy resin can be realized.

1st acrylic resin

The first acrylic resin improves the drying properties of the composition and improves the hardness, water resistance, and chemical resistance of the produced coating film.

The first acrylic resin may include a repeating unit derived from an ethylenically unsaturated monomer and a repeating unit derived from a hydroxyl group-containing (meth)acrylic monomer. That is, the first acrylic resin may be manufactured from an ethylenically unsaturated monomer and a hydroxyl group-containing (meth)acrylic monomer. For example, the first acrylic resin may be prepared from an alkyl group-containing (meth)acrylic monomer and a hydroxyl group-containing (meth)acrylate monomer. That is, the first acrylic resin is a resin that is not acid-modified, and specifically, may be an unmodified acrylic resin.

The ethylenically unsaturated monomer may be one or more selected from the group consisting of styrene and its derivatives, butadiene, C _1-12 alkyl (meth)acryl, and C _1-12 alkyl (meth)acrylic acid ester.

The hydroxyl group-containing (meth)acrylic monomers include, for example, hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, Cardura acrylate, Cardura methacrylate, caprolactone acrylate, caprolactone methacrylate, 2,3-dihydroxypropyl acrylate, 2,3-dihydroxypropyl methacrylate, polypropylene modified acrylate, polypropylene modified methacrylate , 4-hydroxymethyl cyclohexyl-methyl acrylate, and 4-hydroxymethyl cyclo-methyl methacrylate.

As the first acrylic resin, a resin with a high glass transition temperature (Tg) can be used. When using an acrylic resin with a high Tg as described above as the first acrylic resin, there is an advantage of accelerating the drying of the coating film, thereby improving the hardness and water resistance of the coating composition, and thereby various physical properties of the coating film. Specifically, the first acrylic resin may have a glass transition temperature (Tg) of 40 to 65 °C, 45 to 63 °C, or 48 to 57 °C. When the glass transition temperature of the first acrylic resin is within the above range, the curability of the composition and the hardness of the manufactured coating film can be improved. In addition, if the glass transition temperature of the first acrylic resin is less than the above range, the drying speed and crosslink density of the coating film decrease, causing a problem of lowering hardness and water resistance, and if it exceeds the above range, the coating film becomes brittle. Problems with deterioration of appearance and impact resistance may occur.

Additionally, the first acrylic resin may have a number average molecular weight (Mn) of 10,000 to 50,000 g/mol, 15,000 to 40,000 g/mol, or 22,000 to 32,000 g/mol. When the number average molecular weight of the first acrylic resin is within the above range, the appearance characteristics and water resistance of the manufactured coating film are appropriate. In addition, if the number average molecular weight of the first acrylic resin is less than the above range, problems may occur in which the chemical resistance, water resistance, and impact resistance of the manufactured coating film are reduced due to the small molecular weight, and if it exceeds the above range, flow occurs as the molecular weight increases. As the property deteriorates, problems such as deterioration in appearance and mechanical properties may occur.

The first acrylic resin may have a weight average molecular weight (Mw) of 80,000 to 120,000 g/mol, 85,000 to 115,000 g/mol, or 9,000 to 105,000 g/mol. When the weight average molecular weight of the first acrylic resin is within the above range, the appearance characteristics and chemical resistance of the manufactured coating film are appropriate. In addition, if the weight average molecular weight of the first acrylic resin is less than the above range, problems may occur where the chemical resistance, water resistance, and impact resistance of the manufactured coating film are reduced due to the small molecular weight, and if it exceeds the above range, the molecular weight increases as the molecular weight increases. As the property deteriorates, problems such as deterioration in appearance and mechanical properties may occur.

Additionally, the first acrylic resin may have a lower weight average molecular weight than the second acrylic resin.

The first acrylic resin may be included in an amount of 30 to 50% by weight, or 35 to 45% by weight, based on the total weight of the paint composition. If the content of the first acrylic resin is less than the above range, the drying property of the composition is reduced, which causes a problem in that the hardness, gloss, and water resistance of the coating film manufactured from the coating composition containing it are reduced, and if it is more than the above range, the composition As drying progresses quickly, the paint workability and flowability of the composition may be insufficient, which may cause problems in the appearance and impact resistance of the coating film.

2nd acrylic resin

The second acrylic resin reacts with the epoxy-acrylic resin to form a coating film and serves to improve the weather resistance of the manufactured coating film.

The second acrylic resin is an acid-modified acrylic resin. At this time, the acid-modified acrylic resin is an acrylic resin modified with an acid compound. At this time, the acrylic resin that can be used during modification can be used without particular limitation as long as it is generally applicable to the paint composition. Specifically, the second acrylic resin may be an acrylic resin containing a repeating unit derived from an ethylenically unsaturated monomer and a repeating unit derived from a hydroxyl group-containing (meth)acrylic monomer modified with an acid compound. That is, the second acrylic resin may be an acrylic resin prepared from an ethylenically unsaturated monomer and a hydroxyl group-containing (meth)acrylic monomer modified with an acid compound. For example, the second acrylic resin may be an acrylic resin prepared from an alkyl group-containing (meth)acrylic monomer and a hydroxyl group-containing (meth)acrylate monomer modified with an acid compound.

The ethylenically unsaturated monomer may be one or more selected from the group consisting of styrene and its derivatives, butadiene, C _1-12 alkyl (meth)acryl, and C _1-12 alkyl (meth)acrylic acid ester.

The hydroxyl group-containing (meth)acrylic monomers include, for example, hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, Cardura acrylate, Cardura methacrylate, caprolactone acrylate, caprolactone methacrylate, 2,3-dihydroxypropyl acrylate, 2,3-dihydroxypropyl methacrylate, polypropylene modified acrylate, polypropylene modified methacrylate , 4-hydroxymethyl cyclohexyl-methyl acrylate, and 4-hydroxymethyl cyclo-methyl methacrylate.

The acid compound may be a monovalent fatty acid, a polyhydric fatty acid, or a mixture thereof. For example, the fatty acids include benzoic acid, acrylic acid, methacrylic acid, soybean oil fatty acid, tall oil fatty acid, castor oil fatty acid, rice bran oil fatty acid, linseed oil fatty acid, coconut oil fatty acid, lauric acid, linoleic acid, linolenic acid, and oleic acid. Contains one or more selected from the group consisting of lagonic acid, abietic acid, phthalic anhydride, maleic anhydride, isophthalic acid, adipic acid, tetrahydrophthalic anhydride, terephthalic acid, azeleic acid, sebacic acid, fumaric acid, succinic acid, and citric acid. can do.

The second acrylic resin may have an acid equivalent weight (AEW) of 2,000 to 6,000 g/eq, or 3,000 to 5,000 g/eq. When the acid equivalent weight of the second acrylic resin is within the above range, the paint composition has excellent storage properties. In addition, if the acid equivalent of the second acrylic resin is less than the above range, the weather resistance of the produced coating film may be poor, and if it exceeds the above range, the adhesiveness of the produced coating film may be poor.

Additionally, the second acrylic resin may have a glass transition temperature (Tg) of 35 to 60°C, 40 to 60°C, or 45 to 55°C. When the glass transition temperature of the second acrylic resin is within the above range, the curability of the composition and the weather resistance of the manufactured coating film can be improved. In addition, if the glass transition temperature of the second acrylic resin is less than the above range, the drying speed and crosslink density of the coating film decrease, causing a problem of lowering hardness and water resistance, and if it exceeds the above range, the coating film becomes brittle. Problems with poor impact resistance may occur.

The second acrylic resin may have a number average molecular weight (Mn) of 10,000 to 50,000 g/mol, 20,000 to 40,000 g/mol, or 28,000 to 35,000 g/mol. When the second acrylic resin has a number average molecular weight within the above range, the appearance characteristics and water resistance of the manufactured coating film are improved. In addition, if the number average molecular weight of the second acrylic resin is less than the above range, problems may occur where the chemical resistance, water resistance, and impact resistance of the manufactured coating film are reduced due to the small molecular weight, and if it exceeds the above range, flow occurs as the molecular weight increases. As the property deteriorates, problems such as deterioration in appearance and mechanical properties may occur.

Additionally, the second acrylic resin may have a weight average molecular weight (Mw) of 100,000 to 150,000 g/mol, 110,000 to 135,000 g/mol, or 120,000 to 135,000 g/mol. When the weight average molecular weight of the second acrylic resin is within the above range, the appearance characteristics and chemical resistance of the manufactured coating film are appropriate. In addition, if the weight average molecular weight of the second acrylic resin is less than the above range, problems may occur where the chemical resistance, water resistance, and impact resistance of the manufactured coating film are reduced due to the small molecular weight, and if it exceeds the above range, flow occurs as the molecular weight increases. As the property deteriorates, problems such as deterioration in appearance and mechanical properties may occur.

The second acrylic resin may be included in an amount of 3 to 30% by weight, 4 to 20% by weight, or 5 to 15% by weight based on the total weight of the paint composition. If the content of the second acrylic resin is less than the above range, the drying property of the composition is reduced, which causes a problem in that the hardness, gloss, and water resistance of the coating film manufactured from the coating composition containing it are reduced, and if it is more than the above range, the composition As drying progresses quickly, the paint workability and flowability of the composition may be insufficient, which may cause a problem in which the exterior properties of the coating film are deteriorated.

The subject may further include a catalyst.

catalyst

The catalyst serves to increase the crosslinking density of the manufactured coating film.

The catalyst may be one commonly used in topcoat compositions to increase the degree of cross-linking, and may include, for example, a halogen-based catalyst. Specifically, the catalyst may include a chlorine-based catalyst.

The catalyst may be included in an amount of 0.1 to 1.0% by weight, or 0.2 to 0.7% by weight, based on the total weight of the paint composition. If the content of the catalyst is less than the above range, the curability of the composition decreases, which causes a problem in that the hardness of the coating film manufactured from the coating composition containing it decreases. If the content exceeds the above range, the curing of the composition progresses quickly, thereby reducing the hardness of the composition. The problem of shortening the time may occur.

The main agent may additionally include additives that are generally applicable to topcoat compositions as main additives.

Topic Additives

The main additives include, for example, solvents, colorants, surface conditioners, dispersants, wetting agents, co-solvents, anti-foaming agents, thickeners, pH regulators, etc. At this time, each component of the main additive is not particularly limited as long as it is used in the paint composition, and its content is not particularly limited as long as it does not impair the physical properties of the paint composition.

The coloring agent may include one or more selected from the group consisting of colorants and extenders. For example, the coloring agent may include a colorant and an extender pigment. At this time, the colorant may include, for example, metal oxides such as titanium dioxide, carbon black, zinc oxide, ultramarine blue, and red iron oxide; sulfides of lithopone, lead, cadmium, iron, cobalt, aluminum and their hydrochloride or lactate salts; Azo pigment; and copper phthalocyanine pigments. Additionally, the extender pigment may include, for example, one or more selected from the group consisting of barium sulfate, silica, talc, calcium carbonate, and feldspar.

Furthermore, the coloring agent may include a colorant and an extender pigment at a weight ratio of 1.3:1 to 2.5:1, or 1.5:1 to 2.3:1.

Additionally, the extender pigment may have an average diameter of 1 to 5 ㎛, or 1.5 to 3 ㎛. If the diameter of the extender pigment is less than the above range, the oil absorption amount of the pigment is high and the viscosity of the paint composition increases, which causes a problem in that the appearance of the manufactured coating film deteriorates. If it exceeds the above range, the average particle size increases, causing a problem in the manufactured coating film. The surface becomes uneven, deteriorating the appearance and gloss of the coating film, and it becomes vulnerable to penetration from the outside, which can cause problems with poor chemical resistance. At this time, the average diameter of the extender pigment may be the diameter of 50% of the cumulative distribution (D ₅₀ ) in the particle size distribution map measured using a particle size analyzer (PSA).

<Hardener>

The curing agent includes an epoxy-acrylic resin.

Epoxy-acrylic resin

The epoxy-acrylic resin reacts with the second acrylic resin to form a coating film and serves to improve the weather resistance and mechanical properties of the manufactured coating film.

Additionally, the epoxy-acrylic resin may be a core-shell structured resin. For example, the epoxy-acrylic resin may be a resin of a core-shell structure including a core containing an epoxy group and a shell containing an acrylic group. When the epoxy-acrylic resin has a core-shell structure, the initial physical properties such as viscosity and drying speed of the resin can be easily adjusted to the desired level, and the characteristics of two different resins can be expressed simultaneously, so a single resin may not be sufficient. It has the advantage of significantly improving the properties of the coating film.

The epoxy-acrylic resin may have an epoxy equivalent weight (EEW) of 800 to 1,300 g/eq, 900 to 1,200 g/eq, or 950 to 1,100 g/eq. When the epoxy equivalent weight of the epoxy-acrylic resin is within the above range, a uniform and stable core-shell structure is formed to prevent agglomeration or precipitation between particles, resulting in excellent storage stability of the resin and the paint composition containing it. In addition, if the epoxy equivalent weight of the epoxy-acrylic resin exceeds the above range, there is a problem in that it is difficult to form a core-shell structure because it is difficult to wrap a high equivalent weight of epoxy resin (core) with an acrylic resin (shell), and if it is less than the above range, Because low amounts of epoxy resin and acrylic resin are mixed unevenly and cannot form a uniform core-shell structure, storage stability problems may occur.

Additionally, the epoxy-acrylic resin may have a glass transition temperature (Tg) of 5 to 20°C, 7 to 18°C, or 8 to 15°C. When the glass transition temperature of the epoxy-acrylic resin is within the above range, the curability of the composition is appropriate and the flexibility of the manufactured coating film is appropriate, thereby minimizing molecular weight reduction or yellowing phenomenon, and thus the weather resistance of the manufactured coating film is excellent. . In addition, if the glass transition temperature of the epoxy-acrylic resin is less than the above range, the molecular weight or intermolecular attraction is small, so the drying speed and crosslinking density decrease, and the hardness and water resistance of the coating film decrease. If it exceeds the above range, the manufacturing As the coated film becomes brittle, problems with poor impact resistance may occur.

The epoxy-acrylic resin may have a number average molecular weight (Mn) of 35,000 to 55,000 g/mol, 40,000 to 54,000 g/mol, or 44,000 to 50,000 g/mol. When the number average molecular weight of the epoxy-acrylic resin is within the above range, a dense coating film can be formed through appropriate intermolecular bonds, thereby improving the appearance characteristics and water resistance of the manufactured coating film. In addition, if the number average molecular weight of the epoxy-acrylic resin is less than the above range, it may be difficult to form a dense coating film due to the small molecular weight, which may cause problems in that the chemical resistance, water resistance, and impact resistance of the manufactured coating film are reduced, and if it exceeds the above range, it may be difficult to form a dense coating film. , As molecular weight increases, viscosity and flowability decrease, which may lead to poor painting workability and deterioration of appearance and mechanical properties.

Additionally, the epoxy-acrylic resin may have a weight average molecular weight (Mw) of 130,000 to 180,000 g/mol, 14,000 to 17,000 g/mol, or 15,000 to 16,000 g/mol. When the weight average molecular weight of the epoxy-acrylic resin is within the above range, the molecular weight distribution is appropriate, a uniform coating film can be formed, and the coating composition has excellent storage properties. In addition, when the weight average molecular weight of the epoxy-acrylic resin is less than the above range, the number of molecules constituting the chain in the resin is small, so the mechanical properties such as adhesion and strength of the coating film are lowered, and the durability of the coating film is inferior. If the range is exceeded, crystallization of the coating composition may occur, causing a problem of insufficient storage stability.

The epoxy-acrylic resin may be included in an amount of 1.0 to 7.5 wt%, 2.5 to 7.0 wt%, or 3.0 to 7.0 wt% based on the total weight of the paint composition. When the content of the epoxy-acrylic resin is within the above range, the physical properties of the coating film produced by having the advantages of the acrylic resin, such as dryness, weather resistance, and flexibility, and the advantages of the epoxy resin, such as adhesion, corrosion resistance, and hardness, are excellent. In addition, if the content of the epoxy-acrylic resin is less than the above range, there is a problem of poor impact resistance as the produced coating film becomes brittle due to an increase in the glass transition temperature, and if it exceeds the above range, the dryness of the composition As the composition deteriorates, the initial water resistance and mechanical properties of the manufactured coating film may deteriorate.

The curing agent may additionally include additives that are generally applicable to topcoat compositions as curing agent additives.

Hardener additive

Examples of the hardener additive include antifoaming agents, thickeners, and solvents. At this time, each component of the hardener additive is not particularly limited as long as it is used in the coating composition, and its content is not particularly limited as long as it does not impair the physical properties of the coating composition.

<2-liquid type>

The top coat composition may be a two-component type consisting of a base paint and a hardener. For example, the top coat composition may include a first acrylic resin and a second acrylic resin; and a curing agent containing an epoxy-acrylic resin. Specifically, the topcoat composition includes a first acrylic resin, a second acrylic resin, a solvent, a colorant, a surface conditioner, a catalyst, a dispersant, a wetting agent, a solvent, an antifoamer, a thickener, and a pH adjuster; and a curing agent containing an epoxy-acrylic resin, a thickener, and an antifoaming agent.

In addition, when the top coat composition is a two-component type as described above, the base paint and hardener can be stored in separate containers and mixed immediately before use.

The top coat composition may have a viscosity of 80KU to 120KU, or 90KU to 110KU at 25°C. When the viscosity of the top coating composition is within the above range, the storability of the coating composition is improved and painting workability is excellent. In addition, if the viscosity of the top coat composition at 25°C is less than the above range, there may be a problem of poor storage and flowability of the paint composition, and if it exceeds the above range, there may be a problem of poor painting workability of the paint composition. there is.

In addition, the top coat composition according to the present invention as described above contains an epoxy-acrylic hybrid resin, has excellent mechanical properties such as strength, adhesion, and abrasion resistance of the coating film, and contains a quick-drying first acrylic resin to improve the dryness of the composition. The composition is excellent. In addition, the water-based topcoat composition can produce a coating film that has the advantages of an epoxy paint, such as corrosion resistance and mechanical properties, while also having a beautiful appearance and weather resistance as an external coating film.

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

[Example]

Experimental Examples 1 to 22. Preparation of topcoat composition

Top coat compositions were prepared by mixing each component in the composition shown in Tables 1 to 3 below.

(weight%) Experimental Example 1 Experimental Example 2 Experimental Example 3 Experimental Example 4 Experimental Example 5 Experimental Example 6 Experimental Example 7 1st acrylic resin 40 31 40 40 40 40 40 2nd acrylic resin 10 16 10 10 10 10 10 Epoxy-acrylic resin-1 5 8 One - - - - Epoxy-acrylic resin-2 - - - 5 - - - Epoxy-acrylic resin-3 - - - - 5 - - Epoxy-acrylic resin-4 - - - - - 5 - Epoxy-acrylic resin-5 - - - - - - 5 Hydroxy modified acrylic resin - - - - - - - Norbornane diamine (NBDA) adduct - - - - - - - Epoxy-acrylic cold-blended - - - - - - - TiO ₂ 15 15 15 15 15 15 15 Barium Sulfate-1 8 8 8 8 8 8 8 Barium Sulfate-2 - - - - - - Barium Sulfate-3 - - - - - - water 14 14 18 14 14 14 14 Texanol 4 4 4 4 4 4 4 Dipropylglycol n-butyl ether (DPnB) - - - - - - - dispersant 0.3 0.3 0.3 0.3 0.3 0.3 0.3 humectant 0.2 0.2 0.2 0.2 0.2 0.2 0.2 antiseptic 0.4 0.4 0.4 0.4 0.4 0.4 0.4 pH regulator 0.1 0.1 0.1 0.1 0.1 0.1 0.1 thickener 0.3 0.3 0.3 0.3 0.3 0.3 0.3 defoamer 2.4 2.4 2.3 2.4 2.4 2.4 2.4 Halogen-based catalyst 0.2 0.2 0.2 0.2 0.2 0.2 0.2 tin-based catalyst - - - - - - - Tertiary amine catalyst - - - - - - - coloring agent 0.1 0.1 0.2 0.1 0.1 0.1 0.1 total amount 100 100 100 100 100 100 100

(weight%) Experimental Example 8 Experimental Example 9 Experimental Example 10 Experimental Example 11 Experimental Example 12 Experimental Example 13 Experimental Example 14 Experimental Example 15 1st acrylic resin 50 26 40 40 - 44 40 40 2nd acrylic resin 10 24 20 5 17 - 10 10 Epoxy-acrylic resin-1 5 5 5 5 8 6 - - Hydroxy modified acrylic resin - - - - - - - - Norbornane diamine (NBDA) adduct - - - - - - 5 - Epoxy-acrylic cold-blended - - - - - - - 5 TiO ₂ 15 15 15 15 25 17 15 15 Barium Sulfate-1 8 8 8 8 13 9 8 8 Barium Sulfate-2 - - - - - - - - Barium Sulfate-3 - - - - - - - - water 4 14 4 19 23 16 14 14 Texanol 4 4 4 4 7 4 4 4 Dipropyl glycol n-butyl ether (DPnB) - - - - - - - - dispersant 0.3 0.3 0.3 0.3 0.5 0.3 0.3 0.3 humectant 0.2 0.2 0.2 0.2 0.3 0.2 0.2 0.2 antiseptic 0.4 0.4 0.4 0.4 0.7 0.4 0.4 0.4 pH regulator 0.1 0.1 0.1 0.1 0.2 0.1 0.1 0.1 thickener 0.3 0.3 0.3 0.3 0.6 0.3 0.3 0.3 defoamer 2.4 2.4 2.4 2.4 4.2 2.4 2.4 2.4 Halogen-based catalyst 0.2 0.2 0.2 0.2 0.3 0.2 0.2 0.2 tin-based catalyst - - - - - - - - Tertiary amine catalyst - - - - - - - - colorant 0.1 0.1 0.1 0.1 0.2 0.1 0.1 0.1 total amount 100 100 100 100 100 100 100 100

(weight%) Experimental Example 16 Experimental Example 17 Experimental Example 18 Experimental Example 19 Experimental Example 20 Experimental Example 21 Experimental Example 22 1st acrylic resin 40 40 40 40 40 40 40 2nd acrylic resin - 10 10 10 10 10 10 Epoxy-acrylic resin-1 5 5 5 5 5 5 5 Hydroxy modified acrylic resin 10 - - - - - - Norbornane diamine (NBDA) adduct - - - - - - - Epoxy-acrylic cold-blended - - - - - - - TiO ₂ 15 15 15 15 15 15 15 Barium Sulfate-1 8 - - 8 8 8 8 Barium Sulfate-2 - 8 - - - - - Barium Sulfate-3 - - 8 - - - - water 14 14 14 14 14 14.1 13 Texanol 4 4 4 4 4 4 4 Dipropylglycol n-butyl ether (DPnB) - - - - - - - dispersant 0.3 0.3 0.3 0.3 0.3 0.3 0.3 humectant 0.2 0.2 0.2 0.2 0.2 0.2 0.2 antiseptic 0.4 0.4 0.4 0.4 0.4 0.4 0.4 pH regulator 0.1 0.1 0.1 0.1 0.1 0.1 0.1 thickener 0.3 0.3 0.3 0.3 0.3 0.3 0.3 defoamer 2.4 2.4 2.4 2.4 2.4 2.4 2.4 Halogen-based catalyst 0.2 0.2 0.2 - - 0.1 1.2 tin-based catalyst - - - 0.2 - - - Tertiary amine catalyst - - - - 0.2 - - colorant 0.1 0.1 0.1 0.1 0.1 0.1 0.1 total amount 100 100 100 100 100 100 100

At this time, in Experimental Examples 4 and 5, it was impossible to manufacture a topcoat composition due to insufficient physical properties of the epoxy-acrylic resin.

Hereinafter, the manufacturer and product name of each component used in the examples and comparative examples are shown in Table 4 below, where AEW is the acid equivalent, Mn is the number average molecular weight, Mw is the weight average molecular weight, and Tg is the glass transition temperature. , NV is the solid content, SG is the specific gravity, and AHEW is the active hydrogen equivalent.

ingredient note 1st acrylic resin NV: 50% by weight, Tg: 52℃, Mn: 27,805g/mol, Mw: 98,269g/mol
(Unmodified acrylic resin) 2nd acrylic resin AEW: 4,000g/eq, NV: 42.5% by weight, Tg: 49.2℃, Mn: 31,165g/mol, Mw: 127,054g/mol (acid-modified acrylic resin) Hydroxy modified acrylic resin NV: 41% by weight, Tg: 44℃, Mn: 6,500g/mol, Mw: 14,000g/mol Epoxy-acrylic resin-1 EEW: 1,040g/eq, NV: 50.5% by weight, Tg: 12℃, Mn: 46,911g/mol, Mw: 155,488g/mol (core-shell structure) Epoxy-acrylic resin-2 EEW: 790g/eq, NV: 50.5% by weight, Tg: 12℃, Mn: 35,652g/mol, Mw: 118,093g/mol (core-shell structure) Epoxy-acrylic resin-3 EEW: 1,320g/eq, NV: 50.5% by weight, Tg: 12℃, Mn: 59,563g/mol, Mw: 197,469g/mol (core-shell structure) Epoxy-acrylic resin-4 EEW: 1,040g/eq, NV: 50.5% by weight, Tg: 2℃, Mn: 51,452g/mol, Mw: 171,037g/mol (core-shell structure) Epoxy-acrylic resin-5 EEW: 1,040g/eq, NV: 50.5% by weight, Tg: 27℃, Mn: 42,223g/mol, Mw: 139,939g/mol (core-shell structure) Norbornane diamine (NBDA) adduct AHEW: 100g/eg, NV: 60% by weight, Tg: 8℃ Epoxy-acrylic cold-blending EEW: 1,000g/eq, NV: 52% by weight, Tg: 2℃, Mn: 869g/mol, Mw: 1,895g/mol TiO ₂ SG: 4.0, pH: 8.0, oil absorption: 11.0±0.5 cc/g Barium Sulfate-1 SG: 4.3, average particle size (D ₅₀ ): 1.5㎛, pH: 8.5, oil absorption: 13.5±1.5% by weight Barium Sulfate-2 SG: 4.3, average particle size (D ₅₀ ): 5.0㎛, pH: 8.5, oil absorption: 12.0±1.5% by weight Barium Sulfate-3 SG: 4.3, average particle size (D ₅₀ ): 7.5㎛, pH: 8.5, oil absorption: 11.5±1.5% by weight dispersant Manufacturer: BYK, Product name: DISPERBYK-190 humectant Manufacturer: Hannong Chemical, Product Name: FN-10 antiseptic Manufacturer: THOR, Product name: MBS pH regulator Manufacturer: ANGUS, Product Name: AMP-95 thickener Manufacturer: BASF, Product name: PU 1191 defoamer Manufacturer: BASF, Product name: FL 3635 Halogen-based catalyst Manufacturer: SACHEM, Product name: TMACL (tetramethylammonium chloride) tin-based catalyst Dibutyltin dilaurate (DBTDL) Tertiary amine catalyst Manufacturer: EVONIK, Product name: K-54 colorant Manufacturer: Wooshin Pigment, Product Name: AQUALOR

Test example: Evaluation of properties of manufactured coating film

After painting the steel plate with a water-based zinc primer primer with a dry film thickness of 20㎛ (manufacturer: KCC, product name: ECOSIL SUPERB WZ3300) and a water-based epoxy middle coat with a dry film thickness of 40㎛ (manufacturer: KCC, product name: ECOSIL SUPERB WP3400), A paint film specimen was prepared by coating the top coat composition of the above experimental example to a dry film thickness of 40㎛.

The prepared coating film specimen was left at room temperature for 7 ± 2 minutes, dried in an oven at 60°C for 30 minutes, and then left in an oven at 60°C for 1 day to completely cure to prepare the final coating film.

Afterwards, the physical properties of the top coat composition of the experimental example and the final coating film produced were measured in the following manner, and the results are shown in Tables 5 to 8.

(1) Storage stability

After the top coat composition was left at 50°C for 7 days, thickening of the paint composition, precipitation of pigments (TiO ₂ , barium sulfate, and colorant), and phase separation were visually evaluated.

Specifically, the viscosity of the paint increases after storage, if there is no pigment precipitation or phase separation, it is excellent (◎), if the pigment precipitation is soft, it is good (○), if the pigment precipitation is hard, it is average (△), if there is no pigment precipitation, If it was hard and phase separation occurred, it was evaluated as defective (×).

(2) Drying time

After applying the top coat composition, the time required for touch drying and solidification drying at 25°C was measured using the method described in ASTM D1640. At this time, the hard hardening time was measured as the time at which no marks were left on the coating film when the film was pressed hard with the hand and twisted from side to side.

(3) Hardness

The hardness of the fully cured final coating film was measured using a pencil according to the method described in ASTM D3363. The higher the pencil hardness, the better the physical properties were evaluated (in that order: B, HB, F, H).

(4) Glossy

For the final coating film, the 60˚ gloss was measured using a gloss meter according to the method described in ASTM D523.

(5) Adhesion: Crosscut

According to the method described in ASTM D3359, adhesion was measured by drawing 25 squares (2 mm wide At this time, adhesion was expressed as a ratio of the area of the peeled area, 5B if there was no peeling, 4B if the peeled area was less than 5 area%, 3B if the peeled area was more than 5 area% and less than 15 area%, and 3B if the peeled area was more than 5 area% and less than 35 area%. It was rated as 2B, if it was more than 35 area% but less than 65% of the area, it was rated as 1B, and if it was more than 65% of the area, it was rated as 0B.

(6) Impact resistance

The coating film was painted according to the method described in ASTM D2794 and subjected to impact at room temperature (25°C) to measure the presence or absence of cracks or peeling of the coating film. At this time, the impact conditions were evaluated at 100 lbs·in, 80 lbs·in, and 60 lbs·in, and the impact conditions where cracks or peeling occurred in the coating film were expressed as impact resistance.

(7) Pot life (hr)

After adding 12 ± 2% by weight of dilution water of the total amount of the composition to the top coat composition, the change in viscosity of the paint was measured at 1 hour intervals for a total of 3 hours while continuously stirring at 40°C at a speed of 1,000 RPM using Zahn Cup 3. ), and the pot life was measured by measuring the change in viscosity of the paint. At this time, pot life refers to the time when the change in viscosity of the paint is less than 15%.

(8) Sagging

After adding 12 ± 2% by weight of dilution water of the total amount of the composition to the top coat composition, it was applied to a 30cm At this time, the airless sprayer used a pump ratio of 45:1, an input pressure of 4 bar, and a tip size of 815.

After painting, the specimen was placed vertically at room temperature (25°C) and the flowability of the paint was visually observed and evaluated. At this time, the BYK W.F.T gauge was used to measure W.F.T. and the evaluation was based on the following criteria.

Specifically, if there is no flow of paint, it is grade 1, if the border area sags (waving), it is grade 2, if some paint flows (slight sagging), it is grade 3, and if there is a lot of paint flow (severe sagging), it is grade 4. , If the flow of paint was so severe that the border area completely overlapped (collapsed), it was rated as grade 5.

(9) pinhole

After adding 12 ± 2% by weight of dilution water of the total amount of the composition to the top coat composition, a 30cm At this time, the airless sprayer used a pump ratio of 45:1, an input pressure of 4 bar, and a tip size of 815.

After painting, it was left at room temperature (25°C) for about 7 minutes, then dried in an oven at 60°C for 30 minutes, and pinholes on the surface of the coating film were evaluated using a 15x magnifying glass. At this time, the evaluation criteria are as follows: the lower the grade, the better the pinhole characteristics.

Grade 1: No pinholes observed

Grade 2: Average number of pinholes 1 to 4

Grade 3: Average number of pinholes 5 to 10

Grade 4: Average number of pinholes exceeds 10 but less than 20

Grade 5: Average number of pinholes 20 or more

(10) crack

After adding 12 ± 2% by weight of dilution water of the total amount of the composition to the top coat composition, a 30cm At this time, the airless sprayer used a pump ratio of 45:1, an input pressure of 4 bar, and a tip size of 815.

After painting, it was dried at room temperature (25°C) for about 7 minutes, then dried in an oven at 60°C for 30 minutes, and cracks on the surface of the coating film were evaluated using a 15x magnifying glass.

At this time, the evaluation criteria were grade 1 if there were no cracks on the surface of the coating film, grade 2 if there were few micro cracks, and grade 3 if there were many micro cracks or mud cracks.

(11) Chemical resistance-1: NaOH

After exposing the final coating film to a 3% by weight aqueous solution of sodium hydroxide for 120 hours, the degree of blistering of the flat coating film was evaluated according to the evaluation method of ASTM D714. The results were evaluated as follows according to the frequency of blisters that occurred.

Specifically, the size of blisters is evaluated in four levels: fine (8), small (6), medium (4), and large (2), and the frequency of blisters is small (FEW, F) and medium (MEDIUM, M). ), somewhat much (MEDIUM DENSE, MD), and a lot (DENSE, D). In addition, if there were no blisters, it was evaluated as 10, and if the final coating film was peeled, it was evaluated as 0.

(12) Chemical resistance-2: H ₂ SO ₄

After exposing the final coating film to a 3% by weight sulfuric acid aqueous solution for 120 hours, the degree of blister generation in the flat coating film was evaluated according to the evaluation method of ASTM D714. The results were evaluated as follows according to the frequency of blisters that occurred.

Specifically, the size of blisters is evaluated in four levels: fine (8), small (6), medium (4), and large (2), and the frequency of blisters is small (FEW, F) and medium (MEDIUM, M). ), somewhat much (MEDIUM DENSE, MD), and a lot (DENSE, D). In addition, if there were no blisters, it was evaluated as 10, and if the final coating film was peeled, it was evaluated as 0.

(13) Water resistance

After the final coating film was immersed in fresh water at room temperature (25°C) for 15 days, the degree of blister generation in the flat coating film was evaluated according to the evaluation method of ASTM D714. The results were evaluated as follows according to the frequency of blisters that occurred.

Specifically, the size of blisters is evaluated in four levels: fine (8), small (6), medium (4), and large (2), and the frequency of blisters is small (FEW, F) and medium (MEDIUM, M). ), somewhat much (MEDIUM DENSE, MD), and a lot (DENSE, D). In addition, if there were no blisters, it was evaluated as 10, and if the final coating film was peeled, it was evaluated as 0.

(14) Salt water resistance-1: Rust generation

After applying the top coat, the final coating film was completely cured by leaving it at 60℃ for 1 day. After 600 hours of testing in a saltwater spray tester (35±2℃, 5% by weight NaCl aqueous solution) in accordance with ASTM B117, the saltwater resistance was measured by measuring the occurrence of rust. evaluated.

At this time, the evaluation standard is 10 if there is no rust according to ASTM D610, 9 if the rust area is less than 0.03 area%, 8 if it is 0.03 area% or more but less than 0.1 area%, and 0.3 area% or more. If it was less than area%, it was judged as 7, if it was 0.3 area% or more but less than 1 area%, it was judged as 6, if it was more than 1 area% but less than 3 area%, it was judged as 5, and if it was more than 3 area%, it was judged as 4.

(15) Salt water resistance-2: blister formation

After applying the top coat, the final coating film was completely cured by leaving it at 60℃ for 1 day. After testing for 600 hours in a salt water spray tester (35±2℃, 5% by weight NaCl aqueous solution) in accordance with ASTM B117, visually observe whether blisters occurred. Salt water resistance was evaluated.

At this time, the evaluation standard is based on ASTM D714, and the size of blisters is evaluated in four levels: fine (8), small (6), medium (4), and large (2), and the frequency of blisters is small (FEW, It was evaluated at four levels: F), moderate (MEDIUM, M), somewhat much (MEDIUM DENSE, MD), and much (DENSE, D). Additionally, if there were no blisters, it was evaluated as 10, and if the final coating film was peeled, it was evaluated as 0.

(16) Salt water resistance-3: Creep occurrence

After applying the top coat, leave it at 60℃ for 1 day to completely harden. Make a 1mm wide cut with a blade on the topcoat film and test it for 600 hours in a salt water spray tester (35±2℃, 5% by weight NaCl aqueous solution) according to ASTM B117. After the test, salt water resistance was evaluated by measuring the distance (mm) through which rust had penetrated from the sheath.

(17) Weather resistance-1: Color difference (ΔE)

Weather resistance was evaluated by color difference according to ISO 11341, and specifically, the color difference (ΔE) compared to the initial color was measured after the final paint film was exposed outdoors for 600 hours.

(18) Weather resistance-2: Adhesion

Weather resistance was evaluated by adhesion according to ASTM D3359. Specifically, after the coating film was exposed outdoors for 600 hours, adhesion was measured and evaluated in the same manner as item (5).

(19) Weather resistance-3: Impact resistance

Weather resistance was evaluated as impact resistance according to ASTM D3359. Specifically, after the coating film was exposed outdoors for 600 hours, impact resistance was measured in the same manner as item (6).

division target Experimental Example 1 Experimental Example 2 Experimental Example 3 Experimental Example 6 Experimental Example 7 storage stability ○ or more ◎ ○ ○ ○ ○ drying time Dry to touch 30 minutes or less 20 minutes 29 minutes 18 minutes 30 minutes 20 minutes solidification drying 4 hours or less 2.2 hours 3.5 hours 1.9 hours 2.3 hours 2.2 hours Hardness HB or higher H H- H HB- H+ Polish over 35 38 39 38 38 36 Adhesion 5B and above 5B 5B 5B 5B 5B impact resistance 100lbs·inch or more 100 lbs·inch 100 lbs·inch 80 lbs·inch 100 lbs·inch 80 lbs·inch housework time 3 hours or more 3 hours 3 hours 3 hours 3 hours 3 hours sagging Level 3 or higher 1st grade 1st grade 1st grade 1st grade 1st grade Exterior pinhole Level 3 or higher 1st grade 1st grade level 2 1st grade 1st grade crack Level 1 or higher 1st grade 1st grade 1st grade 1st grade 1st grade tolerance
character 3%NaOH over 10 10 8M 10 8F 10 3% H ₂ SO ₄ over 10 10 10 10 10 10 water resistance over 10 10 10 10 8F 10 Flame resistant
Mercury rust 9 or more 10 10 9 9 10 bladder over 10 10 10 10 10 10 creep 1mm or less 0.47mm 0.58mm 0.92 mm 0.85mm 0.62 mm weather resistance color difference 4 or less 1.42 1.35 1.55 1.4 1.37 Adhesion 4B and above 4B 4B 4B 4B 4B impact resistance 80 lbs·inch or more 80 lbs·inch 80 lbs·inch 60 lbs·inch 80 lbs·inch 60 lbs·inch

division target Experimental Example 8 Experimental Example 9 Experimental Example 10 Experimental Example 11 Experimental Example 12 storage stability ○ or more ○ ○ ○ ○ ○ drying time Dry to touch 30 minutes or less 19 minutes 43 minutes 20 minutes 23 minutes 47 minutes solidification drying 4 hours or less 2.1 hours 4.2 hours 2.1 hours 2.2 hours 4.5 hours Hardness HB or higher H+ F H+ HB- B Polish over 35 35 43 38 33 45 Adhesion 5B and above 5B 5B 5B 5B 5B impact resistance 100lbs·inch or more 80 lbs·inch 100 lbs·inch 100 lbs·inch 100 lbs·inch 100 lbs·inch housework time 3 hours or more 3 hours 3 hours 3 hours 3 hours 3 hours sagging Level 3 or higher 1st grade 1st grade 1st grade level 2 1st grade Exterior pinhole Level 3 or higher level 4 1st grade level 5 1st grade 1st grade crack Level 1 or higher 1st grade 1st grade 1st grade 1st grade 1st grade Chemical resistance 3%NaOH over 10 10 4MD 10 10 4MD 3% H ₂ SO ₄ over 10 10 8F 10 10 8MD water resistance over 10 10 10 10 8F 8F salt water resistance rust 9 or more 9 10 9 9 9 bladder over 10 10 10 10 10 8F creep 1mm or less 0.61 mm 0.63mm 0.67 mm 0.72mm 1.10mm weather resistance color difference 4 or less 1.38 1.31 1.32 1.44 0.97 Adhesion 4B and above 4B 4B 4B 4B 4B impact resistance 80 lbs·inch or more 60 lbs·inch 80 lbs·inch 80 lbs·inch 80 lbs·inch 100 lbs·inch

division target Experimental Example 13 Experimental Example 14 Experimental Example 15 Experimental Example 16 Experimental Example 17 storage stability ○ or more ○ ○ ○ ○ ○ drying time Dry to touch 30 minutes or less 25 minutes 24 minutes 27 minutes 49 minutes 20 minutes solidification drying 4 hours or less 2.3 hours 2.2 hours 2.9 hours 4.6 hours 2 hours Hardness HB or higher H- H H- B H Polish over 35 36 34 31 46 25 Adhesion 5B and above 5B 5B 5B 4B 5B impact resistance 100lbs·inch or more 100 lbs·inch 100 lbs·inch 100 lbs·inch 100 lbs·inch 100 lbs·inch housework time 3 hours or more 3 hours 3 hours 3 hours 3 hours 3 hours sagging Level 3 or higher 1st grade 1st grade 1st grade level 3 1st grade Exterior pinhole Level 3 or higher 1st grade 1st grade 1st grade level 3 level 3 crack Level 1 or higher 1st grade 1st grade 1st grade 1st grade 1st grade Chemical resistance 3%NaOH over 10 8F 8MD 6MD 4D 8F 3% H ₂ SO ₄ over 10 10 8F 8M 6MD 10 water resistance over 10 10 10 10 8M 10 salt water resistance rust 9 or more 9 10 9 9 10 bladder over 10 10 10 10 8M 10 creep 1mm or less 0.95mm 0.64mm 0.82mm 1.36 mm 0.48mm weather resistance color difference 4 or less 2.32 3.85 4.32 1.23 1.46 Adhesion 4B and above 3B 4B 4B 3B 4B impact resistance 80 lbs·inch or more 100 lbs·inch 100 lbs·inch 100 lbs·inch 100 lbs·inch 80 lbs·inch

division target Experimental Example 18 Experimental Example 19 Experimental Example 20 Experimental Example 21 Experimental Example 22 storage stability ○ or more ○ X △ ○ ○ drying time Dry to touch 30 minutes or less 19 minutes 25 minutes 15 minutes 22 minutes 19 minutes solidification drying 4 hours or less 1.9 hours 2.6 hours 2.1 hours 2.3 hours 1.8 hours Hardness HB or higher H HB H H H Polish over 35 21 24 33 39 35 Adhesion 5B and above 5B 4B 5B 5B 5B impact resistance 100lbs·inch or more 100 lbs·inch 100 lbs·inch 100 lbs·inch 100 lbs·inch 100 lbs·inch housework time 3 hours or more 3 hours 2 hours 3 hours 3 hours 2 hours sagging Level 3 or higher 1st grade 1st grade 1st grade 1st grade 1st grade Exterior pinhole Level 3 or higher level 4 level 5 level 3 1st grade 1st grade crack Level 1 or higher 1st grade level 2 1st grade 1st grade 1st grade Chemical resistance 3%NaOH over 10 8M 0(Peel off) 8M 8F 10 3% H ₂ SO ₄ over 10 10 4D 10 10 10 water resistance over 10 10 10 10 10 10 salt water resistance rust 9 or more 10 9 10 10 10 bladder over 10 10 8M 10 10 10 creep 1mm or less 0.51mm 1.2mm 0.63 mm 0.75mm 0.51mm weather resistance color difference 4 or less 1.53 1.86 4.14 1.44 1.47 Adhesion 4B and above 4B 2B 3B 4B 4B impact resistance 80 lbs·inch or more 80 lbs·inch 80 lbs·inch 60 lbs·inch 80 lbs·inch 80 lbs·inch

As shown in Tables 5 to 8, the top coat composition of Experimental Example 1 has excellent workability due to appropriate storage stability, drying time, and pot life, and the coating film produced therefrom has hardness, gloss, adhesion, impact resistance, It was excellent in sagging, appearance, chemical resistance, water resistance, salt water resistance, and weather resistance.

On the other hand, Experimental Example 2, which included an excessive amount of epoxy-acrylic resin as a curing agent, lacked chemical resistance.

Experimental Example 3, which included a small amount of epoxy-acrylic resin, lacked impact resistance.

Additionally, Experimental Example 2 containing an excessive amount of epoxy-acrylic resin had insufficient chemical resistance.

Experimental Example 6, which included epoxy-acrylic resin-4 with a low glass transition temperature, lacked chemical resistance and water resistance. Furthermore, Experimental Example 7, which included epoxy-acrylic resin-5 with a high glass transition temperature, lacked impact resistance and weather resistance.

Experimental Example 8, which contained an excessive amount of the first acrylic resin, was poor in appearance characteristics and impact resistance, and Experimental Example 9, which contained a small amount of the first acrylic resin, had a long drying time, resulting in poor workability and poor chemical resistance.

In addition, Experimental Example 10 containing an excessive amount of the second acrylic resin had poor appearance properties, and Experimental Example 11 containing a small amount of the second acrylic resin had reduced hardness and gloss and lacked water resistance.

Experimental Example 12, which did not include the first acrylic resin, had a long drying time, resulting in poor workability, and the hardness, chemical resistance, and water resistance of the manufactured coating film were poor.

Additionally, Experimental Example 13, which did not include the second acrylic resin, lacked chemical resistance and weather resistance.

Experimental Example 14 containing no epoxy-acrylic resin, Experimental Example 15 containing epoxy-acrylic cold-blended rather than a core-shell structure, and Experimental Example 16 containing a hydroxy-modified acrylic resin instead of the second acrylic resin had chemical resistance. It wasn't enough. In particular, Experimental Example 15 lacked gloss and weather resistance, and Experimental Example 16 had a long drying time, which resulted in poor workability, hardness, adhesion, water resistance, salt water resistance, and weather resistance.

Additionally, Experimental Examples 17 and 18 containing large-diameter barium sulfate as a colorant lacked gloss and chemical resistance.

Experimental Example 19, which included a tin-based catalyst as a catalyst, and Experimental Example 20, which included a tertiary amine catalyst, lacked storage stability of the paint, and the produced coating film lacked gloss, chemical resistance, and weather resistance. In particular, Experimental Example 19 was poor in adhesion, appearance, and salt resistance.

In addition, Experimental Example 21 containing a small amount of catalyst had poor chemical resistance, and Experimental Example 22 containing an excessive amount of catalyst had a short pot life and lacked workability.

Claims (6)

A subject matter comprising a first acrylic resin and a second acrylic resin; and
A curing agent containing an epoxy-acrylic resin;
The second acrylic resin is an acid-modified acrylic resin. In claim 1,
The first acrylic resin has a glass transition temperature of 40 to 65 ℃, a number average molecular weight of 10,000 to 50,000 g/mol, and a weight average molecular weight of 80,000 to 120,000 g/mol. In claim 1,
The second acrylic resin has an acid equivalent weight (AEW) of 2,000 to 6,000 g/eq, a glass transition temperature of 35 to 60° C., a number average molecular weight of 10,000 to 50,000 g/mol, and a weight average molecular weight of 100,000 to 150,000 g. /mol, water-based topcoat composition. In claim 1,
The epoxy-acrylic resin has an epoxy equivalent weight (EEW) of 800 to 1,300 g/eq, a glass transition temperature of 5 to 20° C., a number average molecular weight of 35,000 to 55,000 g/mol, and a weight average molecular weight of 130,000 to 180,000 g. /mol, water-based topcoat composition. In claim 1,
Additionally comprising a halogen-based catalyst,
An aqueous topcoat composition comprising 0.1 to 1.0% by weight of a halogen-based catalyst based on the total weight of the paint composition. In claim 1,
An aqueous topcoat composition comprising 30 to 50% by weight of a first acrylic resin, 3 to 30% by weight of a second acrylic resin, and 1.0 to 7.5% by weight of an epoxy-acrylic resin.