KR20150064507A - Thickener for aqueous paint and aqueous paint composition containing the same - Google Patents

Abstract

The present invention relates to a thickener for aqueous paint, which contains aggregative cellulose ether substituted with hydrophobic groups, and an aqueous paint composition containing the same. According to the present invention, a thickener for aqueous paint contains cellulose ether which has hydrophobic groups within a specific substitution degree, to improve thickening and storage stability of an aqueous paint composition and also enhance overall paint physical properties, such as workability, drooping-resistance and color expression. A thickener for aqueous paint may comprise cellulose ether with substituted hydrophobic groups, which are C4-C20 hydrocarbons and whose substitution degree is 0.5-1.0 wt%.

Description

[0001] The present invention relates to a thickener for water-based paints and a water-

The present invention relates to a thickener for water-based paints containing a cyclic cellulose ether substituted with a hydrophobic group, and an aqueous paint composition containing the same.

Water-based paint and other finishing materials have been widely used as building finishing materials for many years due to the protection of concrete materials, the beauty of appearance, the convenience of construction, and the ease of maintenance.

Water-based paints are classified into 100% acrylic emulsions, styrene-acrylic emulsions and vinyl-based emulsions, depending on the types of emulsions. The proportion of use of oil-based paints is higher than that of oil paints due to market demands, economical efficiency, There is a trend.

Further, the water-soluble paint is classified into an outer paint and an inner paint depending on the application. Previously, water paint was used as exterior and inner wall paint for apartments. However, due to the use of eco-friendly materials, environmental regulations for volatile organic compounds (VOC), and environmental air pollution control laws, etc., .

Water-based paints include resins, pigments, and solvents, which alone are difficult to satisfactorily meet the performance requirements of paints and can not be solved with resins or pigments alone. In this case, the additives can be used to improve the physical properties of the paint, and the amount of the additives is small, but it is a very important component in the paint.

In particular, Thixotrophy, which is a contradictory property that the paint has to be painted with a proper film thickness and restores the viscosity after coating after the external force is removed, because the apparent viscosity is low when the shear rate is high, A small amount of thickener is used as the additive in order to satisfy such physical properties. The thickener gives a high viscosity by forming a resin and a pigment with a net structure in the paint. However, the net structure is easily broken due to a high shearing force at the time of coating, and the viscosity of the paint is low, On the other hand, when the force externally applied is removed, the destroyed net structure is recovered and the viscosity rises again, so that the paint after the painting does not flow.

The thickener is used as an additive for water-based paint in addition to thixotropy for the purpose of preventing layer separation of paint, improving workability, thickening property, leveling property and water retention property. A representative example of the thickener is cellulose ether.

Generally, cellulose ethers for aqueous paint thickeners include hydroxyethyl cellulose (HEC), hydrophobic modified hydroxyethyl cellulose (HMHEC) substituted with a hydrophobic group, and hydroxypropyl methyl cellulose Methyl Cellulose, HPMC) are mainly used.

Specifically, the hydroxypropylmethylcellulose has a good thickening efficiency and thus has the advantage of obtaining a high paint viscosity even when used in a small amount. However, the coloring ability is deteriorated and the appearance of color deteriorates due to the addition of the same pigment, .

On the other hand, hydroxyethyl cellulose has an advantage in that it exhibits excellent color development and bubble formation, but has drawbacks in that workability is low and the viscosity efficiency is low due to severe spatter during roller or brushing operation.

The hydrophobic-substituted hydroxyethyl cellulose (HMHEC) developed to remedy such a problem has drawbacks in that it can improve the workability at the time of roller and brushing work of water-based paint, but it is inferior in thickening efficiency and storage stability.

Patent Document 1 (Japanese Patent Application Laid-Open No. 2012-0099327) discloses a synthetic thickener containing cellulose ether. According to this method, physical properties such as storage stability and workability of paints can be improved as a whole, however, in order to realize the synthesis, a vinyl acetate emulsion and an acrylic emulsion which are hydrophobic components together with cellulose ether are included as essential constituents in the thickener The content of the cellulose ether in the thickener is reduced compared with the conventional cellulose ether thickener, and thus the physical properties of the paint due to the thickener are limited.

Accordingly, the market for architectural finishing materials is demanding the development of new cellulose ether thickener which can satisfy workability and various paint properties evenly.

GB 2012-0099327 A

A problem to be solved by the present invention is to provide a thickener for water-based paints which can improve thickening efficiency and storage stability while maintaining workability.

Another object of the present invention is to provide an aqueous paint containing the thickener for water-based paint.

The hydrophobic group is a hydrocarbon group having 4 to 20 carbon atoms (C ₄ to C ₂₀ ), the hydrophobic substitution degree is 0.5 to 1.0% by weight, Based thickener for water-based paints.

Preferably, at least one hydrogen of the hydrophobic group may be substituted with a halogen group, and the halogen group may be at least one selected from fluorine, chlorine, bromine and iodine.

The cellulose ether is preferably at least one selected from the group consisting of alkylcellulose, hydroxyalkylcellulose, and hydroxyalkylalkylcellulose. More preferably, the cellulose ether may be hydroxyethylcellulose, and more preferably, the cellulose The ether may be hydroxyethylcellulose having a hydroxyethyl group degree of substitution (MS) of 0.8 to 4.5.

The viscosity of the cellulose ether is preferably 100 to 20,000 cps based on 1 wt% aqueous solution measured at 25 캜 and 6 rpm in a Brookfield viscometer.

The present invention also provides an aqueous paint composition comprising the thickener for aqueous paint, wherein the content of the thickener is preferably 0.1 to 1.0% by weight based on the total weight of the aqueous paint composition.

According to the present invention, it is possible to improve the thickening efficiency and storage stability of an aqueous paint composition comprising the associative thickener containing cellulose ether having a hydrophobic group within a specific substitution degree range.

Also, by using the thickener, paint properties such as workability, deflection resistance and color development can be improved as a whole.

The present invention relates to a thickener for water-based paint comprising a cellulose ether substituted with a hydrophobic group, wherein the hydrophobic group is a hydrocarbon group having 4 to 20 carbon atoms (C ₄ to C ₂₀ ) and the substitution degree of the hydrophobic group is 0.5 to 1.0 wt% ≪ / RTI >

The cellulose ether thickener of the present invention is a conglomerate thickener having a hydrophobic group in the molecule. In the present specification, the term "recycled" means that the hydrophobic group substituted with the associative thickener interacts with the emulsion in the aqueous paint composition, It is an effect to improve the paint spatter and workability at the time of painting.

The hydrophobic group in is used a hydrocarbon having 4 to _{20 (C 4 ~ C 20)} , there is no time synthesis is less workability improving effect of the latex particles when the number of carbon atoms is 4 is less than the over-association capability if it exceeds 20 The workability is deteriorated and the viscosity of the paint can be excessively high.

The degree of substitution of the hydrophobic group substituted with the cellulose ether is 0.5 to 1.0% by weight, and the degree of substitution thereof means the average weight percentage of the hydrophobic groups bonded per unit of the cellulose of the cellulose ether substituted with the hydrophobic group. When the degree of substitution of the hydrophobic group is less than 0.5% by weight, the effect of improving the workability is insignificant because of a low degree of association with the emulsion particles. On the other hand, when the degree of substitution of the hydrophobic groups is more than 1% by weight, the production efficiency is poor, Is not produced because it may become excessively high.

At least one of the hydrogen atoms in the hydrophobic group may be substituted with a halogen group. As the halogen group, at least one selected from fluorine, chlorine, bromine and iodine is preferably used. In particular, a cetyl bromide group substituted with bromine as a hydrophobic group bromide) is used, it is more preferable since it has less unharmed particles in the product and exhibits the most suitable properties in terms of workability and thixotropy.

Meanwhile, the cellulose ether used in the present invention is preferably one selected from the group consisting of alkylcellulose, hydroxyalkylcellulose and hydroxyalkylalkylcellulose, more preferably the coloring ability, the appearance of the paint and the pigment dispersibility Excellent hydroxyethyl cellulose is used. The degree of substitution (MS) of the hydroxyethyl group of the hydroxyethyl cellulose is preferably 0.8 to 4.5, and the degree of substitution (MS) thereof is preferably an average of the hydroxyethyl groups bonded to one unit of the cellulose of hydroxyethyl cellulose If the degree of substitution of the hydroxyethyl group is less than 0.8, the solubility in water may be lowered. On the other hand, if the degree of substitution is more than 4.5, the production efficiency is decreased and the surface of the product is excessively sticky, .

The cellulose ether preferably has a viscosity of 100 to 20,000 cps, more preferably 8,000 to 13,000 cps, based on 1 wt% aqueous solution measured at 25 캜 and 6 rpm using a Brookfield viscometer. When the viscosity of the cellulose ether is 100 or less, the viscosity efficiency may be low and the amount of the cellulose ether used may increase. In the case of cellulose ether of 20,000 or more, the production efficiency may decrease.

On the other hand, the present invention provides a water-soluble paint containing the thickener.

The content of the thickener is preferably 0.1 to 1.0 wt% based on the total weight of the aqueous paint composition. When the thickener is used in an amount of less than 0.1 wt%, the thickening efficiency, sag resistance, And if it is used in an amount exceeding 1% by weight, there may arise a problem of workability due to a high viscosity or an increase in cost due to an increase in the amount of the input.

In addition to thickeners, water, pigments and common additives such as water-soluble emulsions, dispersants, defoamers, etc. may be used in the aqueous paint compositions according to the present invention as commonly used in the art.

For example, the water used in the aqueous paint composition may be included within the range commonly used in the art, and preferably 25 to 45 wt% of water may be used based on the total weight of the paint composition.

In addition, as the pigment, a coloring pigment such as titanium dioxide may be used, and may also include a body pigment such as aluminum silicate, calcium carbonate, talc, or a combination thereof. Here, the pigment may be contained within a range generally used in this field, and is preferably contained within a range of 35 to 55% by weight, based on the total weight of the paint composition.

As another water-soluble emulsion, a vinyl acetate emulsion or an acrylic emulsion can be used.

The vinyl acetate emulsion or the acrylic emulsion may be prepared by emulsion polymerization of a vinyl acetate monomer composition or an acrylic monomer composition in an aqueous medium (e.g., water) in the presence of a polyvinyl alcohol-based material.

The polyvinyl alcohol-based material may include an anion-modified polyvinyl alcohol such as a sulfonic acid-modified polyvinyl alcohol, a carboxylic acid-modified polyvinyl alcohol, or a combination thereof.

The vinyl acetate-based monomer composition may include a vinyl acetate-based monomer, and the acrylic monomer composition may include an acrylic monomer.

In addition, the vinyl acetate-based monomer composition and the acrylic monomer composition may further include other components.

The vinyl acetate-based monomer may include vinyl acetate. Examples of the acrylic monomer include ethyl acrylate, ethyl methacrylate, methyl acrylate, methyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate , Butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, cyclohexyl acrylate, alkoxyethyl acrylate, or combinations thereof.

Examples of the other components include monomers copolymerizable with the vinyl acetate-based monomer and the acrylic monomer (e.g., divinylbenzene, divinyl adipate, ethylene glycol di (meth) acrylate, diethylene glycol di ) Acrylate); Water-soluble oligomers (e.g., 2-methacrylamide-2-methylpropanesulfonic acid copolymer, sodium methacrylate-4-styrene sulfonate copolymer, polyvinylpyrrolidone, poly (meth) acrylate); Polymerization initiators (for example, potassium persulfate, sodium persulfate, ammonium persulfate, hydrogen peroxide); Polymerization regulators (e. G., Methanol, ethanol, propanol, acetone, dodecyl mercaptan); Emulsifiers (e. G., Sodium lauryl sulfate), and combinations thereof.

The water-soluble emulsion may be contained within a range generally used in this field, and is preferably contained within a range of 10 to 20% by weight, based on the total weight of the paint composition.

The dispersing agent may include sodium citrate, calcium stearate, zinc stearate, distearyldimethylammonium chloride, or a combination thereof.

Examples of the defoaming agent include dimethylpolysiloxane, silicone, silica, sorbitan monostearate, silicone resin, decanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, mineral oil, . ≪ / RTI >

Examples of the preservative include methanethiol, ethanethiol, 1-propanethiol, 2-propanethiol, butanethiol, tert-butyl mercaptan, pentanethiol, coenzyme A, glutathione, cysteine, 2- mercaptoethanol, dithioerythritol, 2-mercapto indole, transglutaminase, or a combination thereof.

The pH adjuster may include ammonia anhydride, ammonium phosphate, dimethylethanolamine, formic acid, sodium bicarbonate, sodium bicarbonate, triethylamine, or combinations thereof.

In addition, additives common to this field can be used within the general scope used in this field.

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to the following examples.

Example  One

The degree of substitution MS of the hydroxyethyl group (average number of moles of hydroxyethyl groups bonded per unit of cellulose) was 2.8, and the substitution degree of cetyl bromide group (-C ₁₆ H ₃₂ Br) as a hydrophobic group (HMHEC) having a viscosity of 1,900 cps was used in an amount of 0.5% by weight based on the weight of the water-insoluble polymer,

That is, a wetting agent, a dispersing agent, a defoaming agent, a cryoprotectant, a pH adjusting agent, a preservative, a coating film forming aid and a thickening agent are added as an additive in order to improve the physical properties of the coating material by using acrylic emulsion resin, white pigment, extender pigment, Aqueous paint paint was prepared. In Table 1, the unit of the content of each component is% by weight.

Aqueous paint composition Water Paint Composition Ratio (wt%) water 36 Wetting agent 0.2 Dispersant 0.4 Defoamer 0.2 Cryoprotectant 1.5 Titanium dioxide (white pigment) 15.1 Aluminum silicate (extender pigment) 7.1 Calcium carbonate (extender pigment) 15.7 Talc (extender pigment) 5.0 antiseptic 0.2 Styrene-acrylic emulsion 17.1 Coating formulation 0.8 pH adjusting agent 0.2 HMHEC thickener 0.5 Sum 100

* Wetting agent: Product name CF-10 sold by DOW

Dispersant: Product name 44S sold by Sanocof Co., Ltd

* Antifoaming agent: Product name SN-1300 sold by Sanocof Co., Ltd

* Freezing agent: Ethylene glycol

* Color pigments: Titanium dioxide (TiO ₂ )

* Extention pigments: aluminum silicate, calcium carbonate, talc

* Preservative: Troysan 174 available from Troy chemical corp.

559)* Styrene-acrylic emulsion (Acronal, sold by BASF)

559)

* Coating formulation: Texanol ™ sold by Eastman chemical company

* pH adjusting agent: AMP-95 sold by Eastman chemical company

Example  2 to 3 and Comparative Example  1 to 4

A water-soluble paint composition was prepared in the same manner as in Example 1, except that the hydroxyethyl cellulose ether (HMHEC) substituted with the hydrophobic group had a hydrophobicity degree and a viscosity as shown in Table 2 below.

CE type Viscosity (cps) Hydrophobicity degree (% by weight) Example 1 High viscosity HMHEC 1,900 0.5 Example 2 High viscosity HMHEC 9,800 0.6 Example 3 High viscosity HMHEC 19,000 0.8 Comparative Example 1 HEC 2,000 - Comparative Example 2 HEC 4,000 - Comparative Example 3 Low viscosity HMHEC 500 0.4 Comparative Example 4 High viscosity HMHEC 28,900 1.3

CE: Cellulose ether

HMHEC: Hydroxyethyl cellulose substituted with a hydrophobic group (cetyl bromide)

HEC: Hydroxyethylcellulose

Viscosity: Viscosity of 1 wt% aqueous solution measured at 25 ° C and 6 rpm with Brookfield viscometer

.

Evaluation example

The water-based paint compositions prepared in the above Examples and Comparative Examples were evaluated for physical properties through the following physical property evaluation methods. The results are shown in Table 3 below.

(1) Workability

Each of the above water-based paint compositions was applied to a slate lap (bouton slate) using an aqueous roller (aqueous roller of artisan brush). During the coating operation, the degree of splashing of the respective aqueous paint compositions to the periphery was visually observed, and the workability was evaluated as 4 grades as described below. The more the water-based paint composition does not bounce well to the periphery, the better the workability.

?: Excellent,?: Good,?: Fair, X:

(2) Thickening efficiency

The KU viscosity of the paint obtained by adding the same amount of the cellulose ether thickener was measured and it was evaluated that the higher the viscosity value, the better the thickening efficiency.

(3) sag resistance

Each of the aqueous paint compositions was applied to a glass plate using an aqueous roller (aqueous roller of artisan brush). When a glass plate coated with water-based paint is scratched in a lateral direction by a Sagmeter (ANTI-SAG METER ASM-3 from Sheen Instruments Limited), the water paint is removed along the direction in which the Sagmeter has passed to form a horizontal point. Thereafter, the glass plate was vertically erected, the water paint was flown down, and the degree of deflection of the horizontal direction was compared. The deflection resistance was evaluated as 4 grades as follows. The greater the number of missing portions, the greater the sag resistance.

?: Excellent,?: Good,?: Fair, X:

(4) Storage stability

After each aqueous paint composition was stored at room temperature for one month, the degree of separation of the precipitate was visually observed, and the storage stability was evaluated as 4 grades as follows. The smaller the degree of separation of the precipitates, the better the storage stability.

?: Excellent,?: Good,?: Fair, X:

(5) Color development

The color development was evaluated by comparing the degree of color developed according to the difference of the thickener by adding the same amount of colored pigment after making the white paint. As a result, 100 parts by weight of white paint prepared by using the paint composition of Table 1 Parts of colored pigment are added and uniformly stirred, and a 100 micron coat is formed on a cover paper using a film applicator. The coatings were dried for over 40 hours to prepare specimens. The color difference between the standard and the standard was evaluated using the colorimeter as follows. The larger the color difference, the better the color development.

?: Excellent,?: Good,?: Fair, X:

Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Workability ◎ ◎ ◎ × × ◎ × Thickening Efficiency (KU) 101 111 127 95 98 95 131 Sag resistance △ ○ ◎ × △ × ◎ Storage stability ○ ◎ ◎ △ △ × ◎ Color development ◎ ◎ ◎ ◎ ◎ ◎ △

With reference to Table 3 above, it can be seen that, in the case of the aqueous paint compositions of Examples 1 to 3 prepared according to the present invention, a comparison using a hydroxyethyl cellulose thickener which does not contain a hydrophobic group (cetyl bromide) or contains less than 0.5% It can be seen that workability, deflection resistance and color development are equal to or more than those of the aqueous paint compositions prepared in Examples 1 to 3, and that the thickening efficiency and storage stability are remarkably excellent. On the other hand, in Comparative Example 4 using a hydroxyethyl cellulose thickener containing 1.3% by weight of a hydrophobic group, workability and color development were poor.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the scope of the present invention is not limited to the disclosed exemplary embodiments but is to be construed as being limited only by the appended claims. Should be construed as being included in the scope of the present invention.

Claims (8)

A cellulose ether substituted with a hydrophobic group,
Wherein the hydrophobic group is a hydrocarbon group having 4 to 20 carbon atoms (C ₄ to C ₂₀ ) and the substitution degree of the hydrophobic group is 0.5 to 1.0 wt%. The method according to claim 1,
Wherein at least one hydrogen of the hydrophobic group is substituted with at least one halogen group selected from the group consisting of fluorine, chlorine, bromine and iodine. The method according to claim 1,
Wherein the cellulose ether is at least one selected from the group consisting of alkylcellulose, hydroxyalkylcellulose, and hydroxyalkylalkylcellulose. The method according to claim 1,
Wherein the cellulose ether is hydroxyethyl cellulose. The method according to claim 1,
Wherein the cellulose ether is a hydroxyethyl cellulose having a degree of substitution (MS) of hydroxyethyl group of 0.8 to 4.5. The method according to claim 1,
Wherein the cellulose ether has a viscosity of 100 to 20,000 cps based on 1 wt% aqueous solution measured at 25 캜 and 6 rpm using a Brookfield viscometer. An aqueous paint composition comprising the thickener for water-based paints of any one of claims 1 to 6. 8. The method of claim 7,
Wherein the content of the thickener is 0.1 to 1.0 wt% based on the total weight of the aqueous paint composition.