KR102322662B1 - Coating Composition - Google Patents

Abstract

The present invention relates to a coating composition capable of realizing a high-brightness metallic appearance.

Description

Coating Composition

The present invention relates to a coating composition capable of realizing a high-brightness metallic appearance.

PCM (Pre-Coated Metal) paint has excellent processability and hardness, and can secure scratch resistance, and is widely used as a paint composition for home appliances. Recently, as the role of interior decoration for home appliances becomes important, the demand for home appliances having a beautiful appearance of various patterns and colorful colors is gradually increasing, and the paint composition used for home appliances is also a direction that can secure the above properties development is in progress.

In particular, the demand for paints realizing a high-brightness metallic appearance is increasing. For example, Korean Patent No. 10-1345057 discloses a method for manufacturing a color steel sheet including a chrome-free paint brush using a polyester resin and a chrome-free primer layer. is starting However, it is impossible to realize the high brightness required by the consumer with such a polyester-based resin composition. In addition, most commercially available products are paints of a spray coating method, and although some PCM paint compositions to which a roll coating method can be applied have been developed, there is a problem that the metallic luminance is not sufficiently excellent.

Accordingly, there is a continuing demand for a paint composition for PCM that is excellent in basic paint properties, realizes a high-brightness metallic appearance, and can apply a roll coating method.

The present invention provides a coating composition capable of realizing a high-brightness metallic appearance with a luminance value of 20 or more.

The present invention provides a coating composition comprising an acrylic resin, a urethane resin, and a cellulose acetate butyrate resin.

The coating composition according to the present invention can realize a high-brightness metallic appearance and can be used in various high-end finishing materials. In addition, the coating composition of the present invention can be applied to a roll coating coating method for PCM, and it is possible to realize a high luminance of 20 or more, so that the number of ink printing processes can be reduced, thereby having the effect of shortening the process.

Hereinafter, the present invention will be described in detail. However, it is not limited only by the following content, and each component may be variously modified or selectively mixed as needed. Accordingly, it should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention.

As used herein, “number average molecular weight” and “weight average molecular weight” are measured by a conventional method known in the art, and may be measured by, for example, a gel permeation chromatograph (GPC) method. "Glass transition temperature" is measured by a conventional method known in the art, for example, it can be measured by differential scanning calorimetry (DSC). A functional group such as “acid value” may be measured by a conventional method known in the art, for example, may represent a value measured by a method of titration.

The coating composition according to the present invention includes an acrylic resin, a urethane resin, and a cellulose acetate butyrate resin. The coating composition according to the present invention may further include a pigment, a curing accelerator, a solvent, and additives commonly used in the art, if necessary.

acrylic resin

The coating composition according to the present invention includes an acrylic resin as a base resin. The acrylic resin serves to impart excellent processability, alkalinity, hardness, corrosion resistance and high luminance appearance characteristics to the coating film.

The acrylic resin may be prepared by polymerizing a (meth)acrylate monomer and a vinyl monomer.

The type of the (meth)acrylate monomer is not particularly limited, but for example, N-methylol acrylamide, 2-hydroxypropyl methacrylate, propyl methacrylate, t-butylaminoethyl methacrylate, dicyclo Pentenyl oxyethyl methacrylate, acrylic acid dimer, hexanediol diacrylate, t-butyl acrylate, triisopropylsilyl acrylate, benzyl methacrylate, hydroxyethyl methacrylate phthalate, 2-hydroxyethyl methacrylic Late, trimethylolpropane triacrylate, tripropylene glycol diacrylate, ethyl methacrylate, diacetone acrylamide, isobutyl methacrylate, hydroxyisopropyl methacrylate, isopropyl methacrylate, cyclohexyl methacrylate Late, triisopropyl silyl methacrylate, isobornyl acrylate, t-butylcyclohexyl methacrylate, trimethylcyclohexyl methacrylate, acrylonitrile, methyl methacrylate, acrylic acid, t-butyl methacrylate, iso At least one selected from bornyl methacrylate, methacrylonitrile, methacrylic acid, acrylamide, methacrylamide, chlorostyrene, and cyclohexylvinyl ether may be used.

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 solid content (NV) of the acrylic resin may be 25 to 55%, for example, 35 to 45%, and the glass transition temperature (Tg) may be 70 to 100 ℃, for example 80 to 90 ℃, acid The thinness may be -10 to 10 mgKOH/g, for example, -5 to 2 mgKOH/g, and the number average molecular weight may be 10,000 to 50,000 g/mol, for example, 25,000 to 35,000 g/mol.

When the glass transition temperature (Tg) of the acrylic resin is less than 70 °C, hot water resistance and hardness may be reduced, and if it is more than 100 °C, chemical resistance and corrosion resistance may be reduced. If the acid value of the acrylic resin is less than -10 mgKOH/g, chemical resistance and weather resistance may be reduced, and if it exceeds 10 mgKOH/g, chemical resistance and corrosion resistance may be reduced. When the number average molecular weight of the acrylic resin is less than 10,000 g/mol, appearance and hardness may be reduced, and if it exceeds 50,000 g/mol, chemical resistance and corrosion resistance may be reduced.

The content of the acrylic resin may be 30 to 60% by weight, for example, 35 to 50% by weight based on the total weight of the coating composition. When the content of the acrylic resin is less than 30% by weight, the processability and chemical resistance of the coating film may be deteriorated, and when the content of the acrylic resin is more than 60% by weight, the luminance value may be reduced.

urethane resin

The coating composition according to the present invention includes a urethane resin as a base resin. The urethane resin functions as a curing agent and also serves to impart high-brightness appearance characteristics to the coating film.

The urethane resin is prepared by reaction of a polyol and an isocyanate.

As the polyol, a conventional polyol used in urethane resin synthesis in the art may be used without particular limitation. Non-limiting examples of the polyol include polyether polyol, polyester polyol, polycaprolactone polyol, polytetramethylene ether diol, polybutadiene diol, polytetramethylene ether ) diol, polypropylene oxide diol, polybutyleneoxide diol, triol, and the like. The above-mentioned components may be used alone or two or more may be used in combination.

As the isocyanate, conventional isocyanate compounds used in urethane resin synthesis in the art may be used without limitation. For example, methylene diphenyl diisocyanate (MDI), toluene diisocyanate (TDI), hexamethylene diisocyanate (Hexa Methylene Di-isocyanate, HMDI), isophorone diisocyanate (Isophorone Di-isocyanate, IPDI), meta xylene diisocyanate (MXDI), tetramethylxylene diisocyanate (TMXDI), diisocyanate made alicyclic by adding hydrogen to the benzene ring of MDI (H12 MDI), xylene diisocyanate (XDI) diisocyanate (hydrogenated XDI) made into an alicyclic by adding hydrogen to the benzene ring of The above-mentioned components may be used alone or two or more may be used in combination.

The viscosity (23 ° C.) of the urethane resin may be 1,000 to 7,000 mPa.s, for example, 2,800 to 5,800 mPa.s, and the solid content (NV) may be 60 to 90%, for example 70 to 80%. and the number average molecular weight may be 500 to 3,000 g/mol, for example, 1,000 to 1,500 g/mol, and the weight average molecular weight may be 1,000 to 5,000 g/mol, for example 1,700 to 2,300 g/mol, The isocyanate equivalent weight may be between 200 and 600 g/eq, for example between 350 and 450 g/eq.

If the number average molecular weight of the urethane resin is less than 500 g/mol, hot water resistance and weather resistance may be reduced, and if it exceeds 3,000 g/mol, corrosion resistance and weather resistance may be reduced. If the isocyanate equivalent of the urethane resin is less than 200 g/eq, corrosion resistance and weather resistance may be reduced, and if it exceeds 600 g/eq, hot water resistance may be reduced.

The content of the urethane resin may be 5 to 40% by weight, for example, 10 to 25% by weight based on the total weight of the coating composition. If the content of the urethane resin is less than 5% by weight, the luminance value may decrease, and if it is more than 40% by weight, chemical resistance and processability of the coating film may be deteriorated.

Cellulose Acetate Butyrate Resin

The coating composition according to the present invention includes a cellulose acetate butyrate resin as a base resin. The cellulose acetate butyrate resin imparts high-brightness appearance characteristics to the coating film and serves to stabilize the metallic orientation.

The butyl group modification rate of the cellulose acetate butyrate resin may be 30 to 65% by weight, for example, 50 to 55% by weight. When the butyl group modification rate of the cellulose acetate butyrate resin is less than 30% by weight, corrosion resistance and chemical resistance may be reduced, and when it exceeds 65% by weight, chemical resistance and weather resistance may be reduced.

Non-limiting examples of the cellulose acetate butyrate resin include Eastman Chemical Japan CAB 551 0.01 (butyl group modification rate 55%), CAB 551 0.2 (butyl group modification rate 55%), CAB 531 1 (butyl group modification rate 53) %), CAB 500 5 (butyl group modification rate 50%), CAB 553 0.4 (butyl group modification rate 55%), CAB 381 0.1 (butyl group modification rate 38%), CAB 381 0.5 (butyl group modification rate 38%) , CAB 381 2 (butyl group modification rate 38%), CAB 381 2BP (butyl group modification rate 38%), CAB 381 20 (butyl group modification rate 38%), CAB 381 20BP (butyl group modification rate 38%), CAB 321 0.1 (32% of butyl group modification rate) is mentioned. The above-mentioned cellulose acetate butyrate resin may be used alone or in combination of two or more.

The solid content (NV) of the cellulose acetate butyrate resin may be 10 to 50%, for example, 25 to 35%, and the glass transition temperature (Tg) may be 80 to 130 ° C., for example 90 to 110 ° C. and the weight average molecular weight may be 10,000 to 50,000 g/mol, for example, 25,000 to 35,000 g/mol.

The content of the cellulose acetate butyrate resin may be 1 to 20% by weight, for example, 5 to 10% by weight based on the total weight of the coating composition.

In the base resin of the present invention, the content of the cellulose acetate butyrate resin is 5 to 15: 95 to 85 by weight, for example, 7 to 10: 93 to 90 by weight with respect to the total content of the acrylic resin and the urethane resin can be When the content of the cellulose acetate butyrate resin is less than a weight ratio of 5:95 with respect to the total content of the acrylic resin and the urethane resin, the luminance value may be lowered due to insufficient floating of aluminum, and when the weight ratio is greater than 15:85 Processability and impact resistance may be reduced.

When the physical properties and content of the cellulose acetate butyrate resin satisfy the above-described ranges, the high-brightness appearance characteristics of the coating film may be further improved, and the metallic orientation may be further stabilized.

polyester resin

The coating composition according to the present invention may further include a polyester resin as a base resin. The polyester resin serves to impart excellent corrosion resistance, processability, chemical resistance, hardness and adhesion to the coating film.

The polyester resin may have a glass transition temperature (Tg) of -10 to 20 °C, for example, 0 to 10 °C, and a hydroxyl value of 0 to 20 mgKOH/g, for example, 0 to 10 mgKOH/g. and the weight average molecular weight may be 10,000 to 35,000 g/mol, for example, 15,000 to 25,000 g/mol.

The content of the polyester resin may be 1 to 10% by weight, for example, 3 to 7% by weight based on the total weight of the coating composition.

When the physical properties and content of the polyester resin fall within the above-described ranges, corrosion resistance, chemical resistance, appearance characteristics, and adhesion to other substrate layers of the coating film may be further improved.

pigment

The coating composition according to the present invention may further include a pigment. The pigment may include conventional extender pigments, colored pigments, or mixtures thereof known in the art.

The extender pigment fills the pores in the coating film, complements the formation of the coating film, and plays a role in imparting oiliness or mechanical properties to the coating film. Therefore, when an extender pigment is included, a good coating film appearance can be obtained, and hardness, impact resistance, rust resistance, etc. can be improved. As the extender pigment, those commonly used in paint compositions may be used without limitation, and non-limiting examples include calcium carbonate, clay, talc, magnesium silicate, kaolin, mica, silica, aluminum silicate, aluminum hydroxide, barium sulfate. etc. The above-mentioned components may be used alone or two or more may be used in combination.

Colored pigments can be used to express a desired color (colored) in a paint or to increase the strength or gloss of a paint film. As these pigments, organic pigments, inorganic pigments, metallic pigments, aluminum-paste, pearls, etc. commonly used in paints may be used without limitation, and these may be used alone or in combination of two or more. have. Non-limiting examples of usable colored pigments include azo-based, phthalocyanine-based, iron oxide-based, cobalt-based, carbonate-based, sulfate-based, silicate-based, chromate-based pigments, and the like, for example, titanium dioxide, zinc oxide, bismuth vana date, cyanine green, carbon black, iron oxide, iron sulfur oxide, navy blue, cyanine blue, and mixtures of two or more thereof.

For example, the coating composition according to the present invention may include a liquid metallic pigment, a solid metallic pigment, a metal paste (eg, aluminum paste) or a mixture thereof as a pigment. When at least one of the liquid metallic pigment, the solid metallic pigment and the metal paste is included, the luminance is increased and the color expression is excellent, so that the physical properties of the object to be coated can be improved. For example, the pigment used in the present invention may be a metal paste or a liquid metallic pigment.

The content of the pigment may be 1 to 25% by weight, for example, 1 to 10% by weight, based on the total weight of the coating composition. When the content of the pigment satisfies the above-mentioned range, the degree of curing of the coating film may be increased, and thus the physical properties of the coating film may be improved.

hardening accelerator

The coating composition according to the present invention may further include a curing accelerator. The curing accelerator accelerates the curing reaction and serves to improve the cycle of high temperature reliability and continuous workability of the paint.

The curing accelerator used in the present invention may be used without any particular limitation as long as it accelerates the curing reaction, and an amine-based compound, a phosphorus-based compound, an acid compound, and a tin-based compound may be used. For example, the coating composition according to the present invention may include a tin-based compound such as dibutyltin dilaurate (DBTDL).

The content of the curing accelerator may be 0.01 to 5% by weight, for example, 0.1 to 2% by weight based on the total weight of the coating composition. When the content of the curing accelerator is out of the above range, workability and moldability may be deteriorated.

solvent

The coating composition according to the present invention may further include a solvent. The solvent improves workability by adjusting the viscosity of the paint, and serves to improve the appearance brightness of the coating film.

As the solvent, a conventional organic solvent known in the art may be used without limitation. As the organic solvent, an aromatic hydrocarbon-based solvent, an ester-based solvent, an ether-based solvent, an alcohol-based solvent, or a mixture thereof may be used. Non-limiting examples of organic solvents that can be used include cyclohexanone, xylene, toluene, cellosolve acetate, methyl ethyl ketone, dibasic ester, propylene glycol methyl ether acetate, butyl acetate, ethyl acetate, propylene glycol monomethyl acetate, 3-methoxy butyl acetate, ethylene glycol butyl ether, diethylene glycol methyl ether, diethylene glycol ethyl ether, diethylene glycol butyl ether, methanol, ethanol, isopropanol, n-butanol, amyl alcohol, butyl carbitol, isophorone or These mixed solvents and the like.

In the present invention, the content of the solvent may be a residual amount that satisfies the total weight (100% by weight) of the coating composition, for example, 1 to 40% by weight based on the total weight of the coating composition. When the content of the solvent falls within the above-mentioned range, workability is improved and excellent physical properties of the coating film can be exhibited.

additive

The coating composition of the present invention may optionally further include additives commonly used in the coating field within a range that does not impair the intrinsic properties of the composition.

Non-limiting examples of additives usable in the present invention include a dispersant, an antifoaming agent, a defoaming agent, a leveling agent, a plasticizer, a colorant, an ultraviolet absorber, a surface conditioner, a softening agent, an adhesion enhancer, a wetting agent, or a mixture thereof.

The dispersant serves to disperse each material constituting the composition and prevent re-agglomeration by maintaining a distance, so that uniform physical properties are expressed in the coating film. As the dispersant, a conventional dispersant known in the art may be used, and for example, a high molecular weight block copolymer type dispersant may be used.

The antifoaming agent serves to enhance the appearance characteristics of the coating film by suppressing air bubbles generated during coating, and any conventional antifoaming agent known in the art may be used without limitation. For example, a silicone-based or non-silicone-based antifoaming agent may be used, for example, a polysiloxane type antifoaming agent may be used.

The leveling agent is to improve the appearance characteristics of the coating film while enhancing adhesion in the composition by leveling the coating composition so that it is coated evenly and smoothly. As the leveling agent, a conventional leveling agent known in the art may be used without limitation, and examples of the leveling agent include acrylic, silicone, polyester, and amine leveling agents.

The plasticizer serves to control the viscosity of the paint composition and improve storage stability. As the plasticizer, conventional ones known in the art may be used without limitation, and for example, an acrylic or polyester plasticizer may be used.

The additive may be appropriately added within a content range known in the art, for example, may be included in an amount of 0.01 to 25% by weight based on the total weight of the coating composition. When the content of the additive is within the above-described range, the appearance and hardness of the coating film may be improved.

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

[Example 1-9]

By mixing each component according to the composition shown in Table 1 below, the coating composition of Examples 1-9 was prepared. The usage unit of each component in Table 1 below is % by weight.

[Comparative Example 1-4]

By mixing each component according to the composition shown in Table 2 below, the coating composition of Comparative Examples 1-4 was prepared. The usage unit of each component in Table 2 below is weight %.

Acrylic resin 1: poly(methyl 2-methylpropenoate-butyl prop-2-enoate-2-hydroxyethyl 2-methylprop-2-enoate), NV 39%, viscosity X, Tg 83 °C, acid value 1 mgKOH/g, Mn 26,500 g /mol

Acrylic resin 2: poly(methyl 2-methylpropenoate-butyl prop-2-enoate-2-hydroxyethyl 2-methylprop-2-enoate), NV 42%, viscosity Z6, Tg 88 °C, acid value -3 mgKOH/g, Mn 33,000 g/mol

Acrylic resin 3: poly(methyl 2-methylpropenoate-butyl prop-2-enoate-2-hydroxyethyl 2-methylprop-2-enoate), NV 40%, viscosity Z6, Tg 65 ° C, acid value 15 mgKOH/g, Mn 36,000 g /mol

Urethane resin 1: HDI type, viscosity (23 ℃) 5,500 mPa.s, NV 78%, Mn 1,500 g/mol, Mw 2,000 g/mol, isocyanate equivalent 410 g/eq

Urethane resin 2: HDI type, viscosity (23 ℃) 3,800 mPa.s, NV 75%, Mn 1,050 g/mol, Mw 1,800 g/mol, isocyanate equivalent 380 g/eq

Urethane resin 3: HDI type, viscosity (23 ℃) 5,500 mPa.s, NV 75%, Mn 3,500 g/mol, Mw 5,500 g/mol, isocyanate equivalent 250 g/eq

CAB 1: Cellulose acetate butyrate resin (CAB 551 0.2 sec (Eastman Kodak), butyl group modification rate 55 wt%, NV 30%, Tg 100 °C, Mn 30,000 g/mol)

CAB 2: Cellulose acetate butyrate resin (CAB 381 2 sec (Eastman Kodak), butyl group modification rate 38 wt%, NV 33%, Tg 130 °C, Mn 40,000 g/mol)

Polyester resin: Tg 7 ℃, hydroxyl value 5 mgKOH/g, Mw 23,000 g/mol

Pigment: Aluminum paste

Curing accelerator: dibutyltin dilaurate

Solvent 1: Isophorone

Solvent 2: Butyl Carbitol

Surface conditioner 1: Acrylic copolymer (TEGO FLOW ZFS460 (EVONIK))

Surface conditioner 2: Thermoplastic acrylic resin (KCC)

Plasticizer: Polyester plasticizer

Anti-foaming agent: Silicone-based anti-foaming agent

[Evaluation of physical properties]

The physical properties of the coating compositions prepared according to Examples and Comparative Examples were measured as shown in Table 3 below, and the results are shown in Tables 4-6 below.

From the results in Table 4-6, the coating film formed of the coating composition of Examples 1-9 according to the present invention was generally superior in physical properties to the coating film formed of the coating composition of Comparative Examples 1-4. In particular, it was confirmed that the coating film formed from the coating composition of Examples 1-9 secured high luminance of 20 or more based on the FI value (flop index), and at the same time, excellent coating film properties such as hardness, workability, heat resistance, and chemical resistance.

On the other hand, in the case of Comparative Example 1, in which the content of the acrylic resin was applied below the content range of the present invention, processability and chemical resistance were inferior, and in Comparative Example 2, the content of the urethane resin was applied below the content range of the present invention, It was confirmed that the luminance value and impact resistance were inferior. In addition, in the case of Comparative Examples 3 and 4 in which the cellulose acetate butyrate resin was applied or not applied in an amount outside the content range of the present invention, it was confirmed that the luminance value and processability were reduced.

Claims (7)

Based on the total weight of the coating composition, 30 to 60% by weight of an acrylic resin, 5 to 40% by weight of a urethane resin, and 1 to 20% by weight of a cellulose acetate butyrate resin,
The urethane resin has a viscosity (23 ° C.) of 1,000 to 7,000 mPa.s, a solid content (NV) of 60 to 90%, a number average molecular weight of 500 to 3,000 g/mol, and a weight average molecular weight of 1,000 to 5,000 g /mol and an isocyanate equivalent weight of 200 to 600 g/eq. The acrylic resin according to claim 1, wherein the acrylic resin has a solid content (NV) of 25 to 55%, a glass transition temperature (Tg) of 70 to 100 °C, an acid value of -10 to 10 mgKOH/g, and a number average molecular weight. A paint composition of 10,000 to 50,000 g/mol. delete The method according to claim 1, wherein the cellulose acetate butyrate resin has a butyl group modification rate of 30 to 65% by weight, a solid content (NV) of 10 to 50%, and a glass transition temperature (Tg) of 80 to 130 ℃, A coating composition having a weight average molecular weight of 10,000 to 50,000 g/mol. The coating composition according to claim 1, wherein the content of the cellulose acetate butyrate resin is 5 to 15: 95 to 85 by weight with respect to the total content of the acrylic resin and the urethane resin. The coating composition according to claim 1, further comprising a polyester resin. The coating composition according to claim 1, further comprising at least one pigment selected from a liquid metallic pigment, a solid metallic pigment, and a metal paste.