KR100978606B1 - Aqueous anticorrosive paint composition - Google Patents

Abstract

PURPOSE: An aqueous anti-corrosive paint composition is provided to secure the rust resistance and the rapid drying time, and to improve the compatibility with a conventional oily and aqueous film. CONSTITUTION: An aqueous anti-corrosive paint composition contains the following: 20~45wt% of acrylic emulsion formed by copolymerizing acryl and a styrene monomer; 25~50wt% of self-cross linkable organic binder including at least one hydroxy group and carboxyl group; 5~15wt% of non-toxic anti-corrosion pigment formed with trimethylated silica; 3~10wt% of silicon based water repellent; and 1~32wt% of one component selected from the group consisting of a coloring pigment, a dispersing agent, a precipitation inhibitor, a special reinforcing material, a thickening agent, a pH adjusting agent, and a leveling agent.

Description

Aqueous antirust coating composition {AQUEOUS ANTICORROSIVE PAINT COMPOSITION}

The present invention relates to an aqueous anti-corrosive coating composition, and more particularly, to an environmentally friendly aqueous anti-corrosive coating composition for inhibiting the rust generation of various steel structures, and to prevent environmental pollution problem in oil-based anti-rust coating.

As the industry develops, various steel structures are exposed to severe corrosive environments due to the toxic gases emitted from the industry and the increase in smoke and other pollution of automobiles every year. For example, rust that occurs in steel structures is a major factor in the deterioration of the durability of steel structures, and the process of returning processed metals to natural stable oxidized compounds (ores). The rust generation factor is attached to the surface of the molten metal, which is caused by moisture penetrating the crystal portion of the metal oxide film to dissolve the metal and oxygen dissolved in the water oxidizes the metal. In addition, the corrosion of the coating film applied to the steel frame is often complicated by aging of the coating film, and the aging is complicated because it depends on a wide variety of factors. Among them, water or water vapor most typically causes corrosion of the coating, and also promotes other aging. When water penetrates into the coating film, it causes swelling, dissolution and the like, thereby aging the polymer material of the coating film. Corrosion factors such as water and oxygen penetrate the aged areas to promote corrosion at the interface of the coating film. Therefore, as with the steel structure, water has the greatest influence on corrosion of the coating film, and when a substance such as salt or carbon dioxide is added thereto, the rust proceeds rapidly. In general, it is known that the higher the water absorbing coating, the lower the corrosiveness.

In general, rust preventive paint is introduced to prevent rust from chemically containing iron by contacting metal, such as air, water, and carbon dioxide, and is generally used in bridges, offshore structures, nuclear power plants, and various plants. It is used to prevent corrosion of steel structures such as large structures, ships, containers, etc., and it must be able to withstand severe corrosive environment for a long time. In addition, the anti-corrosive paint should have good adhesion without passing air or moisture, no cracking, and no problem in weather resistance and durability.

Conventional coating compositions use organic resins and organic solvents, and most of these organic solvents include volatile compounds such as volatile compounds (VOC) and formaldehyde, and when organic substances are absorbed into the human body, they affect the central nervous system and Or it acted as a threat to the health of the user. In addition, there are cases where photoluminescent (heavy lead, red lead), zinc chromate, lead cyanide and strontium chromate containing heavy metals such as chromium or lead are used as rust preventive pigments. Many not only pose a huge threat to the health of workers and consumers, but also cause environmental pollution. In addition, reuse of the remaining diluent can lead to corrosion of the equipment.

Conventional organic rust preventive paints not only have such health and environmental problems, but also have a problem of delaying air due to poor paintability and long drying time during painting work, and thus poor workability.

In order to improve such a problem, a lot of water-based rust-preventive coatings have been recently developed, but in the case of using these water-based rust-preventive coatings, there is still a lot of room for improvement in adhesive properties, hot water resistance, and salt-water resistance properties. In addition, there is a need for the development of an aqueous rust-preventive coating having such antirust and adhesion.

The present invention is to solve the above problems, an object of the present invention is environmentally friendly, does not contain toxic substances such as volatile organic compounds (VOC) and / or formaldehyde contained in conventional organic rust-preventive coating, drying time The present invention provides an aqueous anticorrosive coating composition which is excellent in adhesion to a steel structure and excellent in hot water resistance, cold resistance and rust resistance.

The present invention is to solve the above problems, the aqueous rust-preventive coating composition according to the present invention, 20 to 45% by weight of an acrylic emulsion resin copolymerized with acrylic and styrene monomer; 25 to 50% by weight of a self-crosslinked polymer organic binder comprising at least one hydroxy group and a carboxyl group; 5 to 15% by weight of a non-toxic rust preventive pigment consisting of trimethylated silica; 3 to 10 wt% silicone-based water repellent; And 1 to 32% by weight of an additive consisting of at least one of a coloring pigment, a dispersant, a precipitation inhibitor, a special reinforcing material, a thickener, a pH adjusting agent, and a leveling agent.

The aqueous rust-preventive coating composition according to the present invention contains an organic-inorganic composite binder containing special inorganic particles together with a general organic compound, and has a high solid content and does not contain a volatile organic compound (VOC). Antirust coating composition. Such an aqueous antirust coating composition has a suitable chemical activity, and when acidic water or the like penetrates through a pin hole of a paint film, the corrosive agent reacts with the organic-inorganic mixed binder prior to contacting the steel structure to be corrosive. Loss or, after some dissolution, it is converted to an alkaline atmosphere, thereby inhibiting corrosion of iron. When using such an aqueous rust-preventive coating composition, it has the advantage of removing volatiles in the solvent, lowering the film formation temperature to form a coating film even at low temperatures, and exhibits excellent properties in various aspects such as water resistance, abrasion resistance, color retention, weather resistance, etc. .

Hereinafter, the respective components of the aqueous antirust coating composition according to the present invention will be described.

The acrylic emulsion resin used in the present invention can be used without limitation as long as it is used as a binder of the aqueous rust-preventive coating composition. In particular, in the present invention, vinyl-based monomers such as styrene monomer and ethylene vinyl acetate (EVA) monomer and carboxyl group (-COOH) are used. Resin in which the acrylate containing) copolymerized in the predetermined ratio is used. The acrylic emulsion resin is a solvent-free binder resin containing a large amount of solid content of 45 to 55% by weight and a minimum film forming temperature (MFFT) of preferably 15 to 25 ° C. When penetrating, it reacts with these to partially dissolve and change to alkaline while inhibiting corrosion, thereby improving the rust resistance of the coating film.

Specifically, the acrylic emulsion resin may be an acrylic polymer made of a copolymer comprising at least one of vinyl acetate-based, acrylic emulsion, vinyl sol emulsion. More specifically, such copolymerized acrylic emulsion resin is copolymerized using a latex obtained by copolymerizing an acrylic monomer with a small amount of vinyl monomer, particularly preferably a styrene monomer or ethylene vinyl acetate (EVA). The copolymerization reaction temperature is about 60 ° C. for 3 hours. If the reaction temperature is too high, the particle size becomes large, and if the reaction temperature is too low, gelation occurs. Most of the copolymerization ends in a few hours and the conversion is almost 100%. Other polymerization methods are often difficult to convert 100%, the treatment of unreacted monomers after the reaction is sometimes a problem, but copolymerization has the advantage that no post-treatment step is required.

For example, a polymerization initiator, a styrene monomer, and a methyl methacrylate monomer are added to the solvent and polymerized while stirring to obtain a styrene-acrylate copolymer resin, and when a water-soluble polymerization initiator and a surfactant are added thereto, copolymerized acrylic The rate is generated, and the acrylate thus obtained is combined with the extender pigment, the self-crosslinked polymer organic binder according to the present invention, and the non-toxic rust preventive pigment to have an excellent anti-rust performance.

The content of the acrylic emulsion resin is preferably 20 to 45% by weight, more preferably 25 to 35% by weight in 100% by weight of the total aqueous rust-preventive coating composition, and when the content is contained in less than 20% by weight When the content is lowered and exceeds 45% by weight, the viscosity is lowered, resulting in poor workability and increased content of extender pigments.

The self-crosslinked polymer organic binder used in the present invention consists of a self-crosslinking polymer comprising at least one hydroxyl group and carboxyl group derived from polyol and polyisocyanate.

Specifically, in the method of producing such a self-crosslinked polymer organic binder, for example, after adding a polyester polyol, dimethylpropionic acid and polyisocyanate, the temperature is raised to 120 ° C. and continued to react, and after 2 hours,% NCO (isocyanate) If the weight percent of NCO contained in the raw material is measured to be about 8% or more, the temperature is lowered to 70 ° C. after the addition of butyl acrylate (BA). After reacting for 30 minutes, crosslinking is performed by mixing methylmethacrylate (MMA) which is an initiator and a cross-linker. At this time, the reaction temperature is maintained at about 60 to 65 ℃ to terminate the reaction. Stirring speed is maintained at about 1500rpm. The organic binder thus obtained uses a polyol having a molecular weight of about 1000 to 5000, has at least two hydroxyl groups, and at least one carboxyl group.

The content of the self-crosslinked polymer organic binder is preferably 25 to 50% by weight, more preferably 30 to 40% by weight in the total composition. If the content is less than 25% by weight, the dispersibility is poor in the production of rust-preventive paint. If the content is more than 50% by weight, the viscosity of the paint rises and the drying speed becomes too fast during drying. Not good

In the present invention, as a non-toxic rust preventive pigment composed of trimethylated silica used as inorganic particles for special rust preventive pigments, fumed silica or trimethylated silica is used. In addition, talc and zinc oxide (ZnO) are used. ), Calcium bicarbonate (bicarbonate), light calcium carbonate, mica, barium sulfate (BaSO ₄ ), or the like or a mixture of particles is used as a raw material. That is, pigments that do not contain heavy metals (Pb, Cr and / or Cd) are used. As a non-toxic rust preventive pigment used especially preferably in this invention, what trimethylated fumed silica is used.

These non-toxic anti-rust pigments are dispersed in a self-crosslinked polymer organic binder, react with the binder component to form a dense coating film, partially dissolved in water to form an alkaline atmosphere, and passivate when water contacts a metal surface. The reaction product dissolves in water and serves to prevent rust. In the present invention, by using such trimethylated silica, in particular fumed silica, by reacting with the acrylic emulsion resin and self-crosslinked polymer organic binder to further improve the anti-rust performance, by using a component that is completely harmless to the human body, Eco-friendly and work stability can be improved.

The content of the non-toxic rust preventive pigment used in the present invention is preferably contained in 5 to 15% by weight, more preferably 8 to 15% by weight in the total composition. If the content is less than 5% by weight, the durability and rust prevention performance of the coating film is significantly reduced, if the content exceeds 15% by weight gel reaction occurs during the production of the coating, the coating film is difficult to crack and paint production. Further, more preferably, the relative weight ratio of the self-crosslinked polymer organic binder and trimethylated silica is 55:45 to 75:25, most preferably 60:40 to 70:30.

Next, the silicone-based water repellent used in the present invention includes a silane and / or siloxane, and is a water-repellent agent that complexes a silicon-based compound to volatilize the -OH group in the molecular structure. Such a silicone-based water repellent is a substance which essentially discharges water, carbon dioxide, and the like, which penetrate the coating film, out of the coating film, and improves flexibility and film formation property in the coating film. The silicone-based water repellent used in the present invention is an aqueous emulsion type water repellent, unlike the organic solvent-type water repellent. The principle of water repellent is to exert the property of splashing water by exerting a large contact angle to water and forming a hydrophobic layer with a large contact angle on the surface of the coating to make droplets of contacted water so that the hydrophobic material is physically and chemically firm on the coating. It should be attached on the ground, it will not change over time and it will not affect the temperature change. Such silicone-based water repellents are generally affected by the degree of activity at pH conditions, the emulsion is completely destroyed at pH 9, and the water repellent effect is inhibited below pH 4. In view of such a pH effect, it is preferable that a small amount of the pH adjuster mentioned later is added in this invention.

As such a water repellent, any one of methyl hydrogen polysiloxane, dimethylpolysiloxane, and polyfluroalkylacrylate, generally named H-silicon, may be used alone or in combination of two or more thereof.

The content of the silicone-based water repellent used in the present invention is preferably 3 to 10% by weight, more preferably 5 to 8% by weight in the total composition. If the content of the water repellent is less than 3% by weight, the effect of the water repellent is weak, the initial rust preventive performance is lowered, if it exceeds 10% by weight, the viscosity during production of the paint rapidly rises, productivity and workability is reduced.

In the present invention, in addition to the above configuration, additives such as coloring pigments, dispersants, precipitation inhibitors, special reinforcing agents, thickeners, pH adjusting agents, leveling agents and the like may be further included.

The colored pigment used in the present invention is a powder having a color that can withstand sunlight without dissolving in water, oil, and solvent, and is used to have a color in paint by mixing with a binder.

In the present invention, the coloring pigment is preferably 5 to 20% by weight of the total composition, more preferably 6 to 14% by weight. The coloring pigment content is less than 5% by weight and the coloring effect of the paint is inferior. If it exceeds 20% by weight, the coating film may be cracked and broken, which will soon reduce the durability of the paint. The coloring pigments used in the present invention can be used without limitation the coloring pigments generally used, for example, carbon black, iron oxide, cadmium red, japon red, titanium oxide (TiO ₂ ) alone or these 2 It can mix and use species.

The dispersant serves to efficiently disperse the pigment pigment in the resin binder in a uniformly stable state. As the dispersant used in the present invention, known materials can be used without limitation, and for example, 1 to 5% by weight of a material such as a block copolymer or an aluminum stearate of an pigment affinity polymer. It is preferred that the amount is more preferably 1.5 to 3% by weight. If the content is less than 1% by weight, the dispersibility of the paint is lowered. If the content is more than 5% by weight, the viscosity of the paint increases.

Sedimentation inhibitors are additives that are added to prevent the various pigments from settling on the bottom of the container during storage of the paint, and also serves as a flow inhibitor to prevent the paint from flowing. As the precipitation inhibitor used in the present invention, known materials may be used without limitation, and for example, Benton may be used. Such anti-settling agent is preferably 2 to 8% by weight, more preferably 2.5 to 5% by weight. If the content is less than 2% by weight, the effect of the settling stabilizer is lowered, if the content is more than 8% by weight may cause a problem in the shelf life of the paint may settle the paint.

As the dispersant and precipitation inhibitor used in the present invention, a single or two or more substances such as aluminum-stearate, Natrasol, Benton, Thixaltrol ST and the like can be used. It can be mixed and used.

In addition, in the present invention, a special reinforcing material may be used to increase the strength of the coating film and to prevent rust from reacting with the acrylate and iron. That is, the special reinforcing material serves as an early anti-rust inhibitor to suppress the rust generated by the reaction of acrylate and iron. As a special reinforcing material used in the present invention, sodium benzoate, sodium nitrite, dolomite, blank fixe, or the like may be used alone or in combination of two or more thereof.

As the pH adjuster used for the stability and pH control of the paint, known materials can be used without limitation, for example, ammonia, TEA (triethylamine), DMAE (dimethylaminoethanol), glacial acetic acid, citric acid and the like can be used. have.

As the thickener, for example, a water-dispersible acrylic-acrylic acid copolymer may be used, but is not limited thereto. In addition, as such an additive, a leveling agent, an antifoaming agent, a plasticizer, and the like may be added as necessary.

The aqueous anticorrosive coating composition according to the present invention thus constructed can be applied as the undercoat 3, which also serves as a primer on the surface 2 of the steel structure 1, as shown in FIG. The midway 4 and the topcoat 5 made of the composition may be applied, or the topcoat 5 may be applied immediately. Therefore, the coating material which has a rustproof characteristic can be completed easily, without applying a separate primer, and workability improves.

In addition, the conventional organic-based rust preventive paints have problems of adhesion with inorganic and water-based paints, but since the aqueous rust-preventive paints prepared by the present invention are manufactured by an organic-inorganic synthetic composition, any paint such as organic or inorganic may be applied. Even when used as the top coat 5 or the mid coat 4, there is no problem in adhesion and durability.

The anti-corrosive coating method according to the present invention is used as it is without the weakness of organic anti-corrosive paint, that is, without using a diluent (water or thinner), and contains no volatile organic compound (VOC), so that producers and workers of the paint are also relieved. Can be used and has no effect on environmental pollution.

In addition, the fast drying time allows the subsequent processes to be fast, and the equipment can also be used to reduce environmental pollution by using water, which can solve many problems on site construction.

The coating method of the aqueous rust-preventive coating composition according to the present invention is not particularly limited, and can be applied onto the steel structure, for example, using various coating apparatuses such as airless spray coating, air spray coating, roller, brush coating, and the like. have.

According to the present invention, the drying time is fast and volatile organic compounds (VOC) and formaldehyde which are harmful to the human body and the environment are not released, and when used in the field, since the original product is used without thinner and / or water, the workability is excellent. Aqueous antirust coatings can be provided. Therefore, the aqueous rust-preventive coating according to the present invention does not use a solvent, so there is no solvent smell, there is no fire and hygiene concern, there is little discoloration, and the hardness is high, so the durability is excellent. In addition, a thick coating film of 60㎛ or more is formed by a single coating, and the drying time is fast, so that the repainting time is shortened.

1 is a perspective view showing an embodiment in which the aqueous antirust coating composition according to the present invention is applied to steel

Hereinafter, the evaluation test results of the aqueous antirust coating composition according to the present invention will be described through Examples.

Example

As shown in <Table 1>, additives such as styrene-acrylate copolymerized acrylic emulsion resin, self-crosslinked polymer organic binder, water repellent, non-toxic rust preventive pigment trimethylated silica, and coloring pigment, dispersant, precipitation inhibitor, etc. After the addition, the aqueous rust-preventive coating composition according to Examples 1 to 6 was prepared by stirring at a high speed stirring of 2,000 to 2,500 rpm or more for 40 to 50 minutes using a stirring device (Vessel). Here, non-toxic rust preventive pigments and complexing pigments were used having an average particle size of 500 µm or more.

division
Example One 2 3 4 5 6 Acrylic emulsion resin
(Binder 1) Styrene-acrylate copolymerized acrylic emulsion resin 30 - 30 - 40 - EVA - 38 40 38 25 45 Organic binder Self-crosslinking polymer 37 31 - 35 - 22 Water repellent
Dimethyl Polysiloxane 6 5 5 - 7 - Silane - 8 - 7 - - Antirust Pigment


Trimethylated silica 12 - - - 8 10 Wollastonite - 6 - 9 5 - Cadmium red - - 10 - - - Talc - - - - 5 13 Pigmentation Pigment
Iron oxide 10 - - - 8 - Lake Red - 7 9 7 - 7 Dispersant
Al-stearate 2 - - - - - Natrasol - 3 - 2.5 - - Sediment stabilizer
Benton 3 - 4 - 2 3 Thixatrol - 2 2 1.5 - - Sum 100 100 100 100 100 100

Evaluation

The salt spray test, heavy metal detection test, accelerated weather resistance test, adhesion strength, water resistance, constant temperature and humidity, low temperature and high temperature repeated tests of the aqueous rust-preventive paint prepared by the examples were carried out.

(1) salt spray test

Anticorrosive coating on the iron plate (70mm × 150mm) was coated with about 50㎛ naturally dried at room temperature for 96 hours, and then placed on a salt spray tester for about 600 hours to observe the rust formation and swelling of the dry coating film.

(2) Heavy metal detection test

The anti-corrosive coating solution was tested for heavy metal detection ((lead (Pb), cadmium (Cd), mercury (Hg), hexavalent chromium (Cr ⁺⁶ )) through an ion-bonded plasma (ICP) tester.

(3) accelerated weathering test

Anticorrosive paint is applied to the iron plate (70mm × 150mm) and dried at room temperature for 96 hours, and then placed on an iron plate in a Sunshine Carbon arc for about 500 hours to test for swelling and discoloration of the dry film. Observation and testing.

(4) adhesion strength test

Anticorrosive paint was coated on an iron plate (70mm × 70mm), and then it was naturally dried at room temperature for 96 hours.

(5) water resistance test

Anticorrosive paint was applied to the iron plate (70mm × 150mm), and it was dried naturally at room temperature for 96 hours, and the iron plate was immersed for 3/2 or more in a beaker containing fresh water, and then tested for about 480 hours. Peeling and the like were visually confirmed.

(6) constant temperature and humidity test

Anticorrosive paint on the iron plate (70mm × 150mm) was coated with about 50㎛ and dried naturally at room temperature for 96 hours, then placed on a constant temperature and humidity tester and tested for 480 hours under the conditions of 50 ℃ and 95% humidity. Rust development was observed and tested.

(7) Low temperature high temperature repeat test

The steel plate (70mm × 150mm) was coated with anti-corrosive paint about 50㎛ and dried naturally at room temperature for 96 hours, and then placed on a constant temperature and humidity tester. The cycle was tested for about 36 cycles (540 hours) with one cycle to observe the swelling, cracking, rusting, etc. of the dry coating.

The results of the evaluation test are as shown in Table 2 below.

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Experiment method State of dry coating clear clear clear clear clear clear Visually
inspection Salt spray test (600 hours) clear clear Rust generation Rust generation Rust generation Rust generation KS D 9502 Heavy metal detection test (mg / kg) Not detected Not detected Not detected Not detected Not detected Not detected ICP Accelerated weathering test (500 hours) clear Swelling Swelling Swelling Swelling Swelling KS F 2274 Adhesion strength test (N / cm ² ) 315 152 295 170 288 211 KS M ISO 4624 Water resistance test (480 hours) clear Rust generation Rust generation clear Rust generation Rust generation Visual inspection Constant temperature and humidity test (480 hours) clear clear Swelling Swelling clear Swelling KS M 5000 Low temperature high temperature repeated test (540 hours) clear clear clear Swelling Swelling Swelling KS M 5000 Pollutant emission test
TVOC
(mg / m ² · h) Not detected Not detected Not detected Not detected Not detected Not detected Korean Air Cleaning Association Certification Standard Formaldehyde (mg / kg) Not detected Not detected Not detected Not detected Not detected Not detected US EPA 8315 A

From the results of <Table 2>, it can be confirmed that there is no detection of heavy metals and contaminants throughout the aqueous rust-preventive coating examples according to the present invention. In the case of Example 1 in which the self-crosslinked polymer was applied as the organic binder, it was found that the adhesion strength was excellent and the other properties were also excellent.

Although the preferred embodiment of the present invention has been described above, the present invention may use various changes, modifications, and equivalents. It is clear that the present invention can be equally modified by appropriately modifying the above embodiments. Accordingly, the above description does not limit the scope of the invention as defined by the limitations of the following claims.

1: steel frame 2: steel surface
3: latitude 4: midway
5: top coat

Claims (4)

20 to 45% by weight of an acrylic emulsion resin obtained by copolymerizing acrylic and styrene monomers;
25 to 50% by weight of a self-crosslinked polymer organic binder comprising at least one hydroxy group and a carboxyl group;
5 to 15% by weight of a non-toxic anti-rust pigment consisting of trimethylated silica;
3 to 10 wt% silicone-based water repellent; And
An aqueous antirust coating composition comprising 1 to 32% by weight of an additive consisting of at least one of a coloring pigment, a dispersant, a precipitation inhibitor, a special reinforcing agent, a thickener, a pH adjusting agent and a leveling agent.
The method of claim 1,
The trimethylated silica, water-based anti-corrosive coating composition characterized in that it comprises at least one of fumed silica (silica) or silica.
The method of claim 1,
The weight ratio of the self-crosslinked polymer organic binder and trimethylated silica is 55:45 to 75:25, an aqueous antirust coating composition.
The method of claim 1,
The special reinforcing material, sodium benzoate (sodium benzoate), sodium nitrite (sodium nitrite), dolomite (dolomite), blank fix (Blanc Fixe) of the aqueous anti-corrosive coating composition characterized in that it comprises at least one.

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