KR100461575B1 - Aqueous antirust coating composition using acrylic emulsion resin - Google Patents

Abstract

The present invention relates to a water-based anti-corrosive coating composition using an acrylic emulsion resin, and more particularly, in an anti-corrosive coating composition capable of room temperature drying and low temperature heat drying, the acrylic emulsion resin as a main component and a sieving pigment and a low toxicity anti-corrosive pigment in an optimal ratio. It is a mixed aqueous quick-drying anti-corrosive coating, which has excellent adhesion to metal materials and excellent anti-corrosion properties and durability that existing water-based paints do not have, so high temperature forced drying is impossible, and various metal coatings and automobiles requiring excellent anti-corrosion properties are required. The present invention can be applied to parts, steel structures, etc., and relates to a new water-based rust-preventive coating composition that exhibits excellent anti-rusting properties when coating a system with various types of water-soluble or oil-soluble coatings as well as the role of a top coat as a single coat.

Description

Water-based antirust coating composition using acrylic emulsion resin

The present invention relates to an aqueous anti-corrosive coating composition using an acrylic emulsion resin, and more particularly, in an anti-corrosive coating composition capable of room temperature drying and low temperature heat drying, an acrylic emulsion resin as a main component and a sieving pigment and a low toxicity anti-corrosive pigment in an optimal ratio. It is a mixed aqueous quick-drying anti-corrosive coating, which has excellent adhesion to metal materials and excellent anti-corrosion properties and durability that existing water-based paints do not have, so high temperature forced drying is impossible, and various metal coatings and automobiles requiring excellent anti-corrosion properties are required. The present invention can be applied to parts, steel structures, etc., and relates to a new water-based rust-preventive coating composition that exhibits excellent anti-corrosive properties when coating a system with various types of water-soluble or oil-soluble coatings as well as the role of a top coat as a single coat.

Conventional water-based antirust coatings are widely known as water-soluble alkyd resins, condensation reaction products of acrylic resins and amino resins, and products using water-soluble epoxy resins. Such antirust coating compositions are added for stabilizing paints and dispersing effects of paints. Due to the use of a pigment dispersant containing a surfactant and a water-soluble component, and a water-soluble resin in which a large amount of hydrophilic groups such as -OH, -COOH, and -NH ₂ are introduced into the polymer resin backbone, It has a disadvantage of poor moisture attenuation.

In addition, although a coating composition of a room temperature dry primer type using a water-soluble alkyd resin and an acrylic emulsion resin as a colorant has been proposed, even in this case, the water-soluble resin containing a large amount of hydrophilic group in the polymer skeleton, and the paint storage property and coating workability are improved. The components such as pigment dispersant and thickener (THICKNER) added in order to remain as a water-soluble component in the dried coating film, and there is also a problem that saline spray resistance and hot water resistance is lowered, so that a large amount of harmful heavy metal components (chromium, lead, etc.) Contains rust preventive pigments.

In addition, in the case of the paint composition described above, a separate dispersant is used to disperse the pigment, so that not only the water-soluble component remains in the dry coating film in a large amount, but also rapidly promotes oxidation of the metal material by moisture contained in the paint. Therefore, the deterioration of anti-corrosion function of metal materials and chemical resistance and water resistance of the dry coating film are poor, and the appearance of coating films such as painting workability, dichroism and staining are poor despite the use of excess surfactant and pigment dispersant. There is this.

Thus, in the case of the conventional water-based rust-preventive coating composition, there is room for improvement in corrosion resistance and hot water resistance, and in particular, high-temperature small-type paint having a drying condition of about 130 to 150 ° C. may cause excessive energy costs for drying furnace operation. In addition, there is a critical problem that can not be used in applications where high temperature drying is difficult due to the characteristics of the coating.

Therefore, the present invention is to solve the problems appearing in the high temperature small-type anti-corrosive coating composition containing the conventional harmful heavy metal rust preventive pigments or room temperature-drying primer type coating composition that is weak in water resistance and hot water resistance, the binder main component is a hydrophilic group in the polymer skeleton Volatile organic compound as a highly corrosion-resistant anti-corrosive paint, which is a part of the thermoplastic resin which has been partially introduced, but has a proper composition of the sieving and anti-corrosive pigments and coating film-forming auxiliary solvents to form a dry coating film having excellent coating properties under normal temperature and low temperature baking conditions. Its purpose is to provide water-based rust-preventive paints with a new composition suitable for various environmental regulations related to VOC) emissions and for the regulation of heavy metals such as chromium and lead that are harmful to humans.

The present invention has an acrylic emulsion resin as a main component, a pigment component, a dispersant, an antifoaming agent, a pH adjusting agent. In the anticorrosive coating composition comprising a leveling agent, a coating film forming auxiliary agent, a thickener, an antirust agent, and ion exchanged water, the acrylic emulsion resin contains 22 to 65 wt% of a styrene-modified acrylic emulsion resin, and contains 8 to 4 extender pigments. 25 wt%, 2-10 wt% of rust preventive pigment, 0.5-6.0 wt% of two or more anti-rust inhibitors, and 0.5-3.0 wt% of a thickener.

Referring to the present invention in more detail as follows.

The present invention is a room temperature and low temperature containing a styrene monomer and an acrylate-based thermoplastic acrylic emulsion resin, sieving pigments and rust preventive pigments, coating film forming auxiliary solvent, two or more kinds of anti-rust agent, etc. in a specific ratio and other known additives This is a baking dry aqueous emulsion rust preventive coating that can be formed and dried at room temperature of 15 ℃ or higher, forced drying at low temperature of 60 ~ 100 ℃ as well as coating under high temperature heating and drying conditions of 150 ℃ or lower. It is an antirust coating composition which does not fall in formation and coating-film property.

The paint composition according to the present invention comprises, for example, 22 to 65% by weight of styrene-modified acrylic emulsion resin, 8 to 25% by weight of extender pigment, 2 to 10% by weight of rust preventive pigment, 2 to 22% by weight of pigmented pigment, and two or more different components. 0.5 to 6.0 wt% of the initial anti-rust agent, 0.01 to 2.0 wt% of the leveling agent, 5 to 10 wt% of the coating film forming auxiliary solvent, 0.2 to 1.0 wt% of the pH adjuster, and 25 to 50 wt% of ion-exchanged water.

According to the present invention, the solid content of the water-soluble acrylic emulsion resin in the above configuration is composed of at least 45% by weight of styrene monomer, 48 to 52% by weight of resin, 48 to 52% by weight of ion exchange water, emulsion resin It is preferable to use an average particle size of 80 nm or less and a glass transition temperature (Tg) of 25 to 35 ° C.

If the composition weight ratio of the styrene monomer is less than 45%, the coating film hardness and paint storage stability are lowered, and when the average particle size of the emulsion is larger than 80 nm, the dispersion effect and dispersion stability of the pigments added together are greatly reduced. In addition, there is a problem in that the resin is destroyed by the emulsion particles are destroyed during the physical energy transfer by the dispersing device in the paint manufacturing.

Therefore, through the above limitation of the particle size, it is possible to prevent the degradation of the wetting property and dispersion stabilization, which is the biggest problem of the emulsion resin, and is transmitted when passing through the dispersion device. It is possible to prevent the destruction of the emulsion particles by the impact of physical force.

In addition, the emulsion resin used in the present invention serves as a binder, the addition ratio of the emulsion pigment and the total pigment component including the pigment component added, that is, the coloring pigment, extender pigment, rust preventive pigment is 1: 0.5 to 2.0 Only when added in a weight ratio, an appropriate dry coating film can be formed, and the corrosion resistance of the dry coating film, the water volatility in the coating film, the appearance of the coating film (color separation and stain prevention), the storage stability of the coating container, and the softening function of the coating film during hot water deposition This good state can be maintained, and a good state of dipping, spray coating (including airless spray coating), and the like is maintained.

The aqueous acrylic emulsion resin used as the main component of the present invention is an acrylate monomer and a carboxyl group (-COOH) containing acrylate in an appropriate composition ratio, by controlling the minimum film forming temperature (MFFT) even in room temperature conditions and low temperature baking conditions The resin which has the property that the coating film can be formed stably is used, which is the main element of the coating film formation which greatly affects the film formation and the physical property level of the dry coating film. It not only maintains the durability of the dry coating and provides adhesion to metal coatings, but also keeps the rust prevention effect.

The pigment component which is the main element of the coating film formation in the present invention is particularly important for the use of extender pigments and rust preventive pigments. As extender pigments, for example, aluminum silicate (Al ₂ O ₃ · SiO ₂ ), magnesium silicate (MgO · SiO ₂ ), Calcium carbonate (CaCO ₃ ), barium sulfate (BaSO ₄ ) and the like are used alone or in combination of two or more in an appropriate ratio. This is a major element of the coating film formation, as well as ensuring the durability of the coating film, contributes to the adhesion of the metal material, the stability of the coating film formation, flow prevention, rust resistance, etc., and plays a role of viscosity control of the paint. If too little sieving pigment is used, the durability and rust resistance of the coating film will be lowered, the dryness of the coating will be deteriorated, the hardness of the coating film will be poor even after the drying is completed, and the paintability will be poor at the time of painting work. It is poor, and the water resistance, chemical resistance, and corrosion resistance are deteriorated with poor adhesion to the metal material.

In addition, anti-corrosive pigments provide durability and continuous rust resistance of coatings, for example, zinc phosphate (ZnO.PO ₄ ), aluminum phosphate (AlH ₂ P ₃ O ₁₀ .2H ₂ O), phosphosilicate (Halox), calcium modified silica. (Shieldex) or the like is used alone or in combination of two or more of them in the above ratio, but if the amount thereof is not appropriate, the rust prevention effect is lowered, and there is a fear of poor pigment stability and poor storage stability due to deterioration of paint stability.

In addition, as the coloring pigment to give the color of the coating film, carbon black, iron oxide (Iron Oxide Red), Bayferrox (YIO), rutile (Rutile) TiO ₂ and the like can be used.

Wetting & Dispersing Agents used to enhance the wettability, reaggregation, sedimentation prevention and dispersing effect of the pigments are block copolymers of polymers having a pigment affinity group (e.g. Disper BYK-181, 182, 184, 190, Dispers 720W, etc.), but if the proper amount is not added, the pigment dispersion and stability maintenance effect is poor, the pigment re-agglomeration and sedimentation occurs, there is a problem that the hot water resistance and corrosion resistance is lowered.

In addition, the antifoaming agent is a modified polysiloxane mixture, which is used to prevent foaming during the manufacturing of paints and for the defoaming effect during painting, and the use of a small amount reduces the foaming and the defoaming effect. Is large, and the adhesion between the layers of repainting of the dry coating film is lowered.

PH regulators that are neutralizing agents for maintaining paint stability include ammonia (NH ₄ OH), TEA (triethylamine), DMAE (dimethylaminoethanol), etc. It is used to adjust the pH for prevention, the range is about 7.5 ~ 9.5 is a general stabilization range.

Meanwhile, in the present invention, a flash rust inhibitor (Flash Rust Inhibitor) is used as two or more components, and examples thereof include sodium nitrate, ammonium benzoate, ammonium dichromate, and the like. Zinc, zirconium, calcium, barium, etc. Mixing of corrosion inhibitors of organic complexes containing 1: 1 at the same time at a weight ratio of 1 to 1 is advantageous to increase the anti-rust effect, and prevents the enlargement of corrosion in the salt spray test and occurs on the surface of the coating film. ) The effect of suppressing the occurrence is increased.

In addition, the leveling agent used for the wettability of the material and the spreading (leveling effect) of the coating film and the prevention of creering may be polyether-modified dimethylpolysiloxane, and the film forming auxiliary solvent for the film forming auxiliary function and the freezing prevention effect. As a Coalescing Agent, butyl cellosolve, butyl carbitol, ethylene glycol, propylene glycol, etc. may be used. When these components are excessive, the film drying properties and coating hardness are reduced. Poor paint safety

Water-soluble thickener (Thickner) may be a water-dispersible acrylic ester-acrylic acid copolymer, which is required to adjust the pH between 7 to 10 at the time of input, and to control the viscosity of the paint for the purpose of controlling the viscosity and fluidity of the paint It prevents the flow of paint, aids in the rise of paint, prevents pigment settling in the paint, and maintains stable dispersion of pigment.

As described above, the aqueous rust-preventive coating composition prepared according to the present invention generally has the following general characteristics and coating specifications, so that it can be used by coating the coating object in an appropriate manner.

General nature

(1) Finishing condition: semi-gloss, matte (Gloss 60。/0-50%)

(2) Color: Black, White, Gray, Maroon, Yellow, Other Colors

(3) Drying conditions (general specifications as in Table 1 below)

TABLE 1

(4) Solid content volume ratio: 25-35% (color difference)

(5) Theoretical spread rate: 12.5 ~ 17.5 ㎡ / ℓ (DFT 20 micron standard)

(6) Specific gravity: 1.20 ~ 1.40 (color difference)

(7) Non-volatile content: 40 to 60%

[Painting specifications]

(1) Surface coating

-Completely remove and paint the rust, dust, oil and other contaminants of the coating.

-Appropriate chemical coating (zinc phosphate, iron phosphate, chromate chemical coating) can increase the adhesion and corrosion resistance.

(2) Leading coating: None

(3) Painting conditions

-When painting, the proper temperature is 15 to 25 ℃ and the relative humidity is 40 to 70%.

(4) dilution

Deposition coating: 20 to 40 seconds (Ford Cup # 4, 25 ℃)

Air spray coating: 25 to 45 seconds (Ford Cup # 4, 25 ℃)

-Mix pure water or ion-exchanged water with raw paint properly and stir well before coating.

-The working viscosity may vary depending on the painting method and working conditions, the shape of the workpiece, and the workplace conditions. Use diluent (pure or ion exchanged water) as appropriate.

(5) Coating method: dip coating, spray coating, airless spray painting

(6) Recommended dry film thickness: 20 to 25 µm by one coating

(7) Subsequent coatings: If necessary, apply a suitable oil coating or waterborne top coat.

(8) Storage period: about 6 months (sealed in a cool, dark place)

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited by the Examples.

[ Examples 1-3]

The paint composition was composed of the composition of the following table 2. Table 2 shows the weight percent.

Following is a brief summary of each ingredient shown in Table 2.

Acrylic emulsion resin: Yeungnam Hwaseong Co., Ltd., UREX M0500, containing more than 45% by weight of styrene monomer, average emulsion size of 80 nm or less, glass transition temperature 25 ~ 35 ℃

Dispersant: BYK-Chemie, BYK-184, water-soluble Wetting & Dispersing Agent, high molecular weight block copolymer solution with pigment affinity group

Antifoam: BYK-Chemie, BYK-020, Polysiloxane Antifoam

Leveling agent: BYK-Chemie, BYK-307, polyether-modified dimethylpolysiloxane-based surface modifier

Antirust agent: Henkel-Nopoco, Alcophor827, Antirust and corrosion resistance enhancer, Metal-containing organic salt compound

Thickeners; Joint chemical company, AR-505, acrylic copolymer type thickener

TABLE 2

In order to prepare the composition, the ingredients of Nos. 1 to 8 are sequentially added to the blending tank, mixed, and dispersed at a prescribed particle size (30 μm) or less with a disperser (sand mill). At this time, the temperature of the dispersion is controlled by using a cooling device so that the temperature of the dispersion during the dispersion process is 40 ℃ or less.

Thus, while slowly dispersing the dispersion solution at 200 rpm at low speed, the ingredients of Nos. 9 to 17 were added slowly in small amounts while strictly keeping the order thereof, and then uniform mixing was performed through complete stirring at 500 rpm or more.

After the stirring was completed, the preparation of the paint composition was completed by sealing and stirring the stirring tank for 12 hours to mature.

[ Comparative Examples 1 and 2]

The paint composition was composed of the composition of the following Table 3. In the following Table 3, the unit means weight%.

Following is a brief summary of each component used in Table 3.

Joncryl56: Johnson Polymers, Acrylic resin for dispersing pigments

Acrysol 1-62: Rohm-En-Has, Acrylic copolymer resin for pigment dispersion

Aerosil R-972: product of Degussa, fumed silica, sedimentation prevention and flow control agent

Halox SW-111, a mixture of rust preventive pigments, phosphosilicates and strontium phosphosilicates, manufactured by Hammond Group, Inc.

Rhoplex WL-96: Rohm & Haas Co., Ltd. Acrylic Emulsion Resin for Coating Film Formation

BYK-020: BYK-Chemie Co., Polysiloxane Antifoaming Agent

Joncryl SCX-1520: Acrylic resin for pigment dispersion and coating

Dowanol EB: Dow Chemical Co., Coalescing Solvent

Dowanol DB: Dow Chemical Co., Coalescing Solvent

Sufynol 104H: Solvent-based surface conditioner manufactured by Air Product & Chemical

BYk-301: product by BYk-CHEMIE, coating surface tension modifier, polyether modified dimethyl

Polysiloxane copolymer solution

TABLE 3

In order to manufacture the comparative example 1, the components of numbers 1-7 are mixed, and it disperse | distributes to a grain size below with a sand mill.

The ingredients of Nos. 8 to 17 are sequentially added while stirring the dispersed solution at low speed, and when the addition is completed, the components are stirred at high speed to obtain a uniform mixed state.

In order to manufacture the comparative example 2, the components of numbers 1-6 are mixed, and it disperse | distributes to a grain size below with a sand mill.

The components of Nos. 7 to 15 were added in the same manner as in Comparative Example 1 to complete the production.

In addition, the detailed manufacturing method of Comparative Examples 1-2 was performed similarly to the operation method of the said Example.

Experimental Example

For the paint composition prepared according to the above Examples and Comparative Examples, the physical properties were tested in accordance with each method for the following test items and the results are shown in the table.

However, the physical property test conditions in this experiment were coated on a zinc phosphate coated 0.8T CR steel plate with a dry coating thickness of 20 to 25 μm, dried at 80 ° C. for 20 minutes, and left at room temperature for 7 days before testing the physical properties. Proceeded. The results are shown in Table 4 below.

TABLE 4

As a result, the coating composition according to the present invention has excellent adhesion to the material, and thus has excellent rust resistance, durability, and chemical resistance, so that various coating parts can be obtained, as well as various coating parts, and excellent coating properties can be obtained by low temperature drying operation. It is.

Claims (3)

In the anti-corrosive coating composition composed mainly of an acrylic emulsion resin, which is composed of a pigment component, a dispersant, an antifoaming agent, a pH adjusting agent, a leveling agent, a film forming auxiliary solvent, a thickener, an antifreezing agent and ion exchanged water, The acrylic emulsion resin contains 22 to 65% by weight of styrene-modified acrylic emulsion resin, The extender pigment is 8 to 25% by weight of one or two or more mixtures selected from Al ₂ 0 ₃ · Si0 ₂ , Mg0 · Si0 ₂ , CaC0 ₃ and BaS0 ₄ , As the anti-rust pigment, 2 to 10% by weight of one or two or more selected from zinc phosphate, aluminum triphosphate, phosphosilicate and calcium modified silica, The anti-corrosive agent is 0.5 to 6.0 wt% of a mixture of a compound selected from sodium nitrate, ammonium benzoate and ammonium dichromate, and an organic complex compound containing a metal component selected from zinc, zirconium, calcium and barium, and As the thickener, 0.5 to 3.0 wt% of a water dispersible acrylic ester-acrylic acid copolymer A water-based antirust coating composition using an acrylic emulsion resin, characterized in that it contains. The aqueous emulsion according to claim 1, wherein the acrylic emulsion resin has a constituent weight ratio of styrene monomer of at least 45% or more, an average emulsion particle size of 80 nm or less, and a glass transition temperature (Tg) of 25 to 35 ° C. Antirust coating composition. The water-based antirust coating composition according to claim 1, wherein all of the pigment components comprising the acrylic emulsion resin, the extender pigment, the rust preventive pigment, and the color pigment are mixed at a weight ratio of 1: 0.5 to 2.0.