KR20240063431A - Aqueous acryl copolymer and aqueous coating composition comprising the same - Google Patents

Abstract

The present invention relates to a water-soluble acrylic copolymer and a water-based paint composition containing the same.

Description

Water-soluble acrylic copolymer and aqueous coating composition comprising the same {Aqueous acryl copolymer and aqueous coating composition comprising the same}

The present invention relates to a water-soluble acrylic copolymer and a water-based paint composition containing the same.

Oil-based paints containing urethane resin, epoxy resin, etc. have been generally used for waterproof flooring in construction, and most of the paints for waterproof flooring currently used in Korea are oil-based paints and contain a large amount of petroleum-based solvents. Accordingly, many problems arise such as volatilization of volatile organic compounds during painting work, causing air pollution, high fire risk, and adversely affecting the health and safety of workers by causing bad odors.

To solve this problem, technology using water-based paints has been proposed. For example, Korean Patent No. 10-2173210 uses water, acrylic-urethane copolymer emulsion, fluororesin emulsion, hydrophobic silica airgel, titanium oxide, hardener, and curing. Disclosed is a water-based paint composition containing an accelerator and a method of forming a waterproof coating film using the same. However, conventional water-based paints are difficult to apply due to poor adhesion due to poor wetting on concrete and other organic coating films.

Accordingly, there is a demand for a water-based paint composition that is environmentally friendly because it does not contain organic solvents and has improved adhesion of the paint film by exhibiting smooth wettability on the concrete substrate.

Conventional acrylic emulsions are in the form of polymers floating in water, and have the surface tension of water, so they have poor penetration into the substrate and require an organic solvent to attach the particles to form a coating film. The present invention lowers the surface tension of water because the polymer is dissolved in water, has good penetration into the substrate, and does not contain an organic solvent to form a coating film, so it is environmentally friendly and has excellent adhesion of the coating film by exhibiting smooth wettability on various substrates. A water-based coating composition is provided.

The present invention relates to a water-soluble acrylic copolymer obtained from a copolymer composition containing an ethylenically unsaturated monomer, a carboxyl group-containing monomer, a hydroxyl group-containing monomer, a carbonyl group-containing monomer, a dihydrazide monomer, and an epoxy group-containing monomer, and a water-based paint composition containing the same. provides.

The present invention provides a water-based paint composition that is environmentally friendly because it does not contain organic solvents and has excellent coating film adhesion by exhibiting smooth wettability on various substrates. The water-based paint composition according to the present invention can be applied to eco-friendly water-based flooring.

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

The “weight average molecular weight” used in this specification is measured by a common method known in the relevant technical field, and can be measured, for example, by the GPC (gel permeation chromatograph) method. “Acid value” and “hydroxyl value” The same functional group is measured by a common method known in the relevant technical field. For example, the “glass transition temperature” can be measured by a titration method. For example, “viscosity” can be measured by differential scanning calorimetry (DSC), and is measured by conventional methods known in the art, for example, Brookfield at room temperature (25°C). It can be measured using a viscometer. “Particle size (D50)” is measured by a common method known in the art and can be measured, for example, by a laser particle size analyzer.

<Water-soluble acrylic copolymer>

The water-soluble acrylic copolymer of the present invention can be prepared from a copolymer composition containing an ethylenically unsaturated monomer, a carboxyl group-containing monomer, a hydroxyl group-containing monomer, a carbonyl group-containing monomer, a dihydrazide monomer, and an epoxy group-containing monomer. The copolymer composition may further include a polymerization initiator, emulsifier, molecular weight regulator, neutralizer, plasticizer, etc.

The ethylenically unsaturated monomers include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, 2-ethylhexyl ( One or more types selected from the group consisting of meth)acrylate, styrene, alpha-methyl styrene, and lauryl (meth)acrylate may be used, but are not limited to these.

The copolymer composition may include 5 to 80% by weight, for example, 10 to 50% by weight of the ethylenically unsaturated monomer, based on the total weight of monomers. If the content of the ethylenically unsaturated monomer exceeds the above-mentioned range, the content of the hydroxyl group-containing monomer that reacts with the curing agent may decrease, which may deteriorate the physical properties of the coating film, and if it is less than the above-mentioned range, the hardness, weather resistance, and adhesion of the coating film may decrease. This can become inferior.

The carboxyl group-containing monomer has hydrophilicity and provides water dispersion stability by forming an anion group when neutralized with an amine compound, and is an olefinic unsaturated monomer containing a carboxyl group and a carboxylic anhydride group. The carboxyl group-containing monomers include dibasic acids or anhydrides such as acrylic acid, methacrylic acid, β-carboxylethyl acrylate, crotonic acid, fumaric acid, maleic anhydride, itaconic acid, and maleic acid monoalkyl ester. One or more types selected from the group consisting of monoalkyl esters may be used, but are not limited to these.

The copolymer composition may include 1 to 30% by weight, for example, 3 to 25% by weight of the carboxyl group-containing monomer, based on the total weight of monomers. If the content of the carboxyl group-containing monomer exceeds the above-mentioned range, hydrophilic groups may become excessive, resulting in increased viscosity, decreased water resistance, and shortened pot life, and if less than the above-mentioned range, water dispersion may not occur properly and storage stability after water dispersion This can go bad.

The hydroxyl group-containing monomer undergoes a crosslinking reaction by reacting with polyisocyanate, which is a curing agent of a water-dispersible two-component urethane paint composition, and is an unsaturated monomer containing a hydroxyl group, such as a hydroxyalkyl ester of unsaturated acrylic acid. The hydroxyl group-containing monomer includes a hydroxyl group-containing monomer whose alkyl group has 2 to 12 carbon atoms, for example, 2-hydroxy ethyl (meth)acrylate, 2-hydroxy propyl (meth)acrylate, 4-hydroxy One or more types selected from the group consisting of oxybutyl (meth)acrylate and caprolactone-modified hydroxy (meth)acrylate may be used, but are not limited to these.

The copolymer composition may include 1 to 50% by weight, for example, 3 to 30% by weight of the hydroxyl group-containing monomer, based on the total weight of monomers. If the content of the hydroxyl group-containing monomer is less than the above-mentioned range, the formation of a coating film by a crosslinking reaction may be insufficient, resulting in poor coating film physical properties, and if it exceeds the above-mentioned range, the adhesion of the coating film may be poor.

The carbonyl group-containing monomer serves to improve adhesion by crosslinking with adipic hydrazide to form a hydrogen bond. The carbonyl group-containing monomers include acrolein, diacetone acrylamide, formyl styrene, vinyl alkyl ketone having 4 to 7 carbon atoms, diacetone acrylate, acetone nitrile acrylate, diacetone methacrylate, 2- One or more types selected from the group consisting of hydroxypropyl acrylate acetyl acetate and butanediol-1,4-acrylate acetyl acetate may be used, but are not limited to these. For example, the carbonyl group-containing monomer may include diacetone acrylamide (DAAM), acrolein, vinyl methyl ketone, diacetone acrylamide, etc.

The copolymer composition may include 1 to 10% by weight, for example, 3 to 8% by weight of the carbonyl group-containing monomer, based on the total weight of monomers. If the content of the carbonyl group-containing monomer is less than the above-mentioned range, the bonding reaction with dihydrazide may be weak, resulting in poor adhesion to the substrate and coating film strength, and if it exceeds the above-mentioned range, discoloration may occur.

The dihydrazide monomer may be one or more selected from the group consisting of dihydrazides of dicarboxylic acids having 2 to 10 carbon atoms, for example, 4 to 6 carbon atoms, but is not limited thereto. For example, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, maleic acid dihydrazide. One or more types selected from the group consisting of dragide, fumaric acid dihydrazide, and itaconic acid dihydrazide can be used.

The copolymer composition may include 0.5 to 5% by weight, for example, 1.5 to 4% by weight of the dihydrazide monomer, based on the total weight of monomers. If the content of the dihydrazide monomer is less than the above-mentioned range, the bonding reaction with the carbonyl group-containing monomer may be weak, resulting in poor substrate adhesion and coating film strength, and if it exceeds the above-mentioned range, discoloration may occur.

The epoxy group-containing monomer is used as a viscosity regulator. A high molecular weight of acrylic copolymer is required for water resistance, impact resistance, and hardness of the coating film, but if the molecular weight of acrylic copolymer is increased under a limited amount of solvent, the viscosity increases excessively, making water dispersion process impossible or water-soluble acrylic copolymer It may become difficult to obtain coalescence. To solve this problem, the viscosity can be lowered by adding a solvent, but in this case, water dispersion stability may become poor. The epoxy group-containing monomer can be polymerized by reacting with the carboxyl group-containing monomer, and serves to lower the viscosity when the molecular weight increases.

As the epoxy group-containing monomer, glycidyl ester compounds of α-branched monocarboxylic acids can be used, for example, neodecaotic glycidyl ester, glycidyl acrylate, glycidyl methacrylate, One or more selected from the group consisting of itaconic acid diglycidyl ester, butene tricarboxylic acid triglycidyl ester, and p-styrene carboxylic acid glycidyl ester may be used, but are not limited to these.

The copolymer composition may include 1 to 30% by weight, for example, 5 to 20% by weight of the epoxy group-containing monomer, based on the total weight of monomers. If the content of the epoxy group-containing monomer is less than the above-mentioned range, sufficient low viscosity may not be formed, making it difficult to manufacture a solvent-free acrylic copolymer, and if it exceeds the above-mentioned range, the hardness of the coating film may decrease due to the low glass transition temperature of the reactive compound. may deteriorate.

The copolymer composition may include 75 to 95% by weight, for example, 80 to 90% by weight of the monomer mixture, based on the total weight (solid content) of the copolymer composition. If the content of the monomer mixture is less than the above-mentioned range, the viscosity may increase excessively when dispersed in water, and if it exceeds the above-mentioned range, the coating film may become sticky.

The copolymer composition may further include a plasticizer. Since the plasticizer is in liquid form and can be used as a solvent, it can further increase the molecular weight of the acrylic copolymer without adding additional solvent, and when dispersed in water, it imparts hydrophobicity to the inner core of the acrylic copolymer particles, thereby stabilizing the particle structure. By maximizing the dispersion stability during water dispersion can be greatly improved.

As the plasticizer, a plasticizer capable of dissolving the acrylic copolymer of the present invention can be used. For example, a plasticizer such as diisobutyl adipate, which is environmentally friendly due to its high boiling point and does not contain a hydroxy group and thus does not affect curing, can be used.

The copolymer composition may include 0.1 to 30% by weight, for example, 1 to 10% by weight of the plasticizer, based on the total weight (solid content) of the copolymer composition. If the content of the plasticizer is less than the above-mentioned range, the effect may be insufficient, and if it exceeds the above-mentioned range, the glass transition temperature of the acrylic copolymer may be lowered, resulting in poor coating film properties.

The copolymer composition may further include a polymerization initiator. The polymerization initiator includes azo compounds such as 2,2'-azobisisobutyronitrile, 2,2'-azobis-(2-methylbutyronitrile), benzoyl peroxide, auroyl peroxide, and gummenhydride. One or more types selected from the group consisting of peroxides such as peroxide, t-butylperoxy-2-ethylhexanoate, and t-amylperoxy-2-ethylhexanoate may be used, but are not limited to these. .

The copolymer composition may include 0.1 to 20% by weight, for example, 1 to 10% by weight of the polymerization initiator, based on the total weight (solid content) of the copolymer composition.

The water-soluble acrylic copolymer of the present invention can be prepared by radical polymerization of the copolymer composition. The polymerization temperature may be 0 to 200° C., for example 120 to 180° C.

The prepared acrylic copolymer can be neutralized with a neutralizing agent. The above agent may be one or more selected from the group consisting of secondary or tertiary amines, such as dimethylethanolamine, N-methyldiethanolamine, diethanolamine, and triethanolamine, but is not limited thereto. . The mixing ratio of the carboxylic acid group in the acrylic copolymer and the neutralizing agent may be 100:30 to 150, for example, 100:50 to 100 molar ratio.

The neutralized acrylic copolymer undergoes a water dispersion process to form an acrylic copolymer dispersion. The acrylic copolymer can be dispersed in water by adding water dropwise while stirring, for example, by slowly adding ion-exchanged water at a temperature of 100° C. or lower.

The weight average molecular weight of the acrylic copolymer in the acrylic copolymer dispersion may be 1,000 to 50,000 g/mol, for example, 2,000 to 30,000 g/mol. If the weight average molecular weight of the acrylic copolymer is less than the above-mentioned range, it may become difficult to secure the water resistance and water dispersion stability of the coating film, and if it exceeds the above-mentioned range, workability may become poor or leveling properties may be poor, thereby ensuring an excellent appearance. It may become difficult to do.

The hydroxyl value of the acrylic copolymer in the prepared acrylic copolymer dispersion is 50 to 200 mgKOH/g, for example, 80 to 150 mgKOH/g, and the acid value is 10 to 50 mgKOH/g, for example, 15 to 35 mgKOH. /g, the glass transition temperature is 0 to 30 ° C, for example 5 to 25 ° C, the viscosity is 10 to 2,000 CPS (25 ° C), for example 500 to 1,700 CPS (25 ° C), and the solid content is 35 to 25 ° C. 50% by weight, for example 35 to 45% by weight, and the particle size (D50) may be 50 to 200 nm, for example 70 to 150 nm. If the hydroxyl value of the acrylic copolymer is less than the above-mentioned range, the strength may be reduced when the coating film is cured, or the viscosity may be excessive when dispersed in water, making synthesis unstable, and if it exceeds the above-mentioned range, the water resistance of the coating film may be poor. If the acid value of the acrylic copolymer is less than the above-mentioned range, the viscosity may be excessive when dispersed in water, making synthesis unstable, and if it exceeds the above-mentioned range, the water resistance of the coating film may be reduced. If the glass transition temperature of the acrylic copolymer is below the above-mentioned range, the strength of the coating film may be poor, and if it is above the above-mentioned range, the viscosity may be excessive when dispersed in water, making synthesis unstable. If the viscosity of the acrylic copolymer is less than the above-mentioned range, the pigment may precipitate when manufacturing the paint, and if it exceeds the above-mentioned range, the leveling property of the paint may be reduced and the appearance of the paint film may be poor. If the solid content of the acrylic copolymer is less than the above-mentioned range, paint mixing design may become difficult, and if it exceeds the above-mentioned range, the resin viscosity may be excessive and the leveling property of the paint may be reduced. If the particle size (D50) of the acrylic copolymer is less than the above-mentioned range, the binding force may decrease, and if it is greater than the above-mentioned range, resin precipitation may occur.

<Water-based paint composition>

The water-based coating composition of the present invention includes a main part containing the above-described water-soluble acrylic copolymer and a curing agent part containing a curing agent. The water-based paint composition according to the present invention may optionally contain a dispersant, anti-freezing agent, wetting agent, neutralizer, anti-foaming agent, pigment, leveling agent, antioxidant, ultraviolet absorber, ultraviolet stabilizer, flow regulator, polymerization inhibitor, antibacterial agent, coupling agent, surfactant. , lubricants, flame retardants, colorants, etc. may further include additives commonly used in the relevant technical field.

As the curing agent, a polyisocyanate compound containing a hydrophilic group may be used. For example, AQ-130 (NIPPONPOLYURETHANE), Bayhydur 3100 (Bayer), Bayhydur 2655 (Bayer), Bayhydur 2547 (Bayer), asaqua XL 600 (Vancorex), etc. can be used.

The mixing ratio of the isocyanate group in the curing agent to the hydroxyl group in the acrylic copolymer may be 1:0.5 to 5, for example, 1:1 to 3 equivalent ratio.

The mixing ratio of the main part and the hardener part may be 1 to 10:1, for example, 2 to 5:1 by weight. If the ratio of the main part to the hardener part exceeds the above-mentioned range, tacky may occur in the coating film due to non-curing, which may result in poor contamination resistance, and if it is less than the above-mentioned range, the pot life is excessively short, impairing workability. You may become inferior.

The water-based coating composition of the present invention can be used on various substrates, for example, concrete, various coating films, wood, fiber, etc. In particular, the water-based paint composition of the present invention exhibits smooth wettability on the concrete substrate and provides excellent film adhesion, so it is suitable for application to concrete and various coating films. Various coating methods can be used, including dipping, spray, roll coat, and brush.

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

[Experimental Example 1-13]

Acrylic copolymer dispersion of each experimental example was prepared according to the composition shown in Table 1-3 below. The physical properties of the acrylic copolymer dispersion prepared according to each experimental example are listed in Table 1-3 below.

[Production Example 1-13]

Using the acrylic copolymer dispersion of each experimental example, the main part was prepared by mixing the ingredients in Table 4 below at a speed of 1,000 to 1,500 rpm. Bayhydur 2655 (Bayer) was used as a hardener. The water-based coating composition of each preparation example was prepared by mixing the main part and the hardener part at a ratio of 5:1 (weight ratio).

[Physical property evaluation]

The physical properties of the coating composition of each production example were measured by the method below, and the results are shown in Tables 5 and 6 below.

pot life

The main part and the hardener part were mixed at 4:1 (weight ratio) at 25°C, and the time for the viscosity to increase was measured.

Polish

The paint composition of each production example was applied to transparent glass at a thickness of WET 250 MICRON METER, dried for 16 hours at a temperature of 23 ± 2 ° C. and a relative humidity of 50 ± 5%, and then the gloss was measured.

Adhesion

The paint composition of each manufacturing example was painted on the oil-based urethane flooring coating, and after drying for 2 days, the adhesion to the urethane coating was measured by Cross Cut (100*100). In addition, the paint composition of each manufacturing example was painted on concrete, and after drying for 2 days, the adhesion to concrete was measured by Cross Cut (100*100).

water resistance

The paint composition of each production example was applied to the oil-based urethane flooring at a thickness of WET 250 MICRON METER, and the appearance was checked after drying. After soaking in water, wrinkles, swelling, cracks, peeling, discoloration, etc. were observed with the naked eye and evaluated on the basis of excellent (5) ⇔ poor (1).

As shown in Tables 5 and 6, the paint composition of Preparation Examples 1-7 using the acrylic copolymer according to the present invention showed excellent physical properties in all measurement items. On the other hand, Preparation Example 8 using an acrylic copolymer that does not contain an epoxy group-containing monomer, Preparation Examples 9-12 using an acrylic copolymer whose content of each monomer is outside the scope of the present invention, and an acrylic copolymer that does not contain an epoxy group-containing monomer. The coating composition of Preparation Example 13 using showed inferior physical properties in all measurement items compared to the coating composition of Preparation Example 1-7.

Claims (6)

Based on the total weight of monomers, 5 to 80% by weight of ethylenically unsaturated monomer, 1 to 30% by weight of carboxyl group-containing monomer, 1 to 50% by weight of hydroxyl group-containing monomer, 1 to 10% by weight of carbonyl group-containing monomer, dihydrazide. A water-soluble acrylic copolymer obtained from a copolymer composition containing 0.5 to 5% by weight of monomers and 1 to 30% by weight of epoxy group-containing monomers. The water-soluble acrylic copolymer according to claim 1, wherein the epoxy group-containing monomer includes a glycidyl ester compound of an α-branched monocarboxylic acid. The water-soluble acrylic copolymer according to claim 1, further comprising 0.1 to 30% by weight of a plasticizer, based on the total weight (solid content) of the copolymer composition. 4. The water-soluble acrylic copolymer according to claim 3, wherein the plasticizer is diisobutyl adipate. The method of claim 1, wherein the acrylic copolymer in the acrylic copolymer dispersion formed through the water dispersion process of the water-soluble acrylic copolymer has a weight average molecular weight of 1,000 to 50,000 g/mol and a hydroxyl value of 50 to 200 mgKOH/g. , the acid value is 10 to 50 mgKOH/g, the glass transition temperature is 0 to 30 ℃, the viscosity is 10 to 2,000 CPS (25 ℃), the solid content is 35 to 50% by weight, and the particle size (D50) is 50 to 50. 200 nm water-soluble acrylic copolymer. An aqueous paint composition comprising a main portion containing the water-soluble acrylic copolymer of any one of claims 1 to 5 and a curing agent portion containing a curing agent.