KR102514941B1 - Coating composition - Google Patents

Abstract

The present invention relates to a rust-preventive paint composition comprising an alkyd resin.

Description

Coating composition {COATING COMPOSITION}

The present invention relates to a rust-preventive paint composition comprising an alkyd resin.

As a rust-preventive paint for preventing corrosion of steel parts such as buildings, ships, automobiles, and industrial machinery, paints containing alkyd resins have been used. Conventional alkyd paints are organic solvent-type paints that emit volatile organic compounds (VOCs) to cause environmental pollution. Accordingly, research and development to reduce the amount of VOCs produced are being actively conducted in accordance with increasingly strict domestic and foreign environmental regulations. For example, Korean Patent Publication No. 2017-0089186 discloses a paint composition using a solvent-free alkyd resin prepared by a condensation reaction of an unsaturated fatty acid, a polybasic acid, and a polyhydric alcohol. However, there is a problem in that the paint does not exhibit sufficient anti-rust property.

On the other hand, conventional anti-corrosion paints often contain Gwangmyeongdan (Pb ₃ O ₄ ), but Kwangmyeongdan has a very high specific gravity of 8.7, which increases the weight of the paint and can cause musculoskeletal disorders in workers. In addition, it contains lead (Pb), a heavy metal, which can adversely affect workers' health and the environment. Accordingly, there is an increasing demand for paints having a low heavy metal content or not containing heavy metals.

The present invention provides a high solid type coating composition with low emission of VOCs and excellent rust prevention without containing heavy metals.

The present invention provides a coating composition comprising an alkyd resin and inorganic fine particles.

The present invention provides an eco-friendly coating composition of a high solid type with low emission of VOC. In addition, the coating composition of the present invention exhibits an excellent rust prevention effect without containing heavy metals.

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

As used herein, “number average molecular weight” and “weight average molecular weight” are measured by a conventional method known in the art, and can be measured, for example, by a gel permeation chromatograph (GPC) method.

The coating composition of the present invention contains an alkyd resin and inorganic fine particles. The coating composition of the present invention may further include at least one selected from the group consisting of a pigment, a solvent, and an additive, if necessary.

alkyd resin

The coating composition of the present invention contains an alkyd resin. The alkyd resin serves to form a coating film. The alkyd resin may be prepared through a method known in the art, and may be prepared, for example, by polymerization through an esterification reaction of an acid monomer and an alcohol monomer.

The acid monomer may include a fatty acid, an acid anhydride, a monovalent or more basic acid, or a mixture thereof.

As the fatty acids, unsaturated fatty acids, saturated fatty acids, synthetic fatty acids, and the like may be used. Non-limiting examples of the unsaturated fatty acids include coconut oil, castor oil, grape seed oil, linseed oil, oiticica oil, and palm oil. ), palm kernel oil, safflower oil, sunflower oil, soya bean oil, tung oil, tall oil, dehydrated castor oil castor oil) and the like, and these may be used alone or in combination of two or more.

As the acid anhydride, those commonly known in the art may be used without particular limitation. For example, phthalic anhydride, maleic anhydride, tetra hydro phthalic anhydride, chlorendic anhydride, acetic anhydride, acetic benzoic anhydride, succinic anhydride, glutaric acid Acid anhydride, benzoic acid anhydride, etc. can be used. These may be used alone or in combination of two or more.

The monovalent or more basic acid is a type of acid containing at least one carboxyl group in a molecule, and any monovalent or more aromatic or aliphatic acid commonly known in the art may be used without particular limitation. For example, adipic acid, oxalic acid, malonic acid, malic acid, fumaric acid, maleic acid, succinic acid, Sebacic acid, glutaric acid, aspartic acid, tartaric acid, pimelic acid, suberic acid, citric acid, iso Monovalent or higher aliphatic base acids such as isocic acid, aconitic acid, propane-1,2,3-tricarboxylic acid -trivalent aliphatic base acid); Benzoic acid, p-tert-butylbenzoic acid (PTBBA), phthalic acid, isophthalic acid, dimethylisophthalic acid, benzene-1,3,5-tricar Monovalent aromatics such as benzene-1,3,5-tricarboxylic acid and 5-sulfo-1,2,4-benzenetricarboxylic acid There are basic acids (eg, monovalent aromatic basic acids) and the like. These may be used alone or in combination of two or more.

The alcohol monomer includes a C ₁ -C ₁₀ polyhydric alcohol. The C ₁ -C ₁₀ polyhydric alcohol is an alcohol having a high molecular weight and can be ester-bonded with an acid monomer to improve the flexibility of the resin, as well as improve room temperature dryness and hardness of the resin.

Non-limiting examples of the C ₁ -C ₁₀ polyhydric alcohol include C ₁ -C ₁₀ dihydric alcohols such as neopentyl glycol and 1,6-hexanediol; C ₁ -C ₁₀ trihydric alcohols such as trimethylol propane, trimethylol ethane, and 1,2,6-hexanetriol; C ₁ -C ₁₀ tetrahydric alcohols such as pentaerythritol, diglycerol, and sorbitol; and C ₁ -C ₁₀ 5-6 valent alcohols such as mannitol and dipentaerythritol. These may be used alone or in combination of two or more.

The mixing ratio of the acid monomer and the alcohol monomer described above is not particularly limited, and may be, for example, 1:1 to 1.5, and another equivalent ratio of 1:1 to 1.2. When the mixing ratio of the alcohol monomer to the acid monomer is less than the above range, the viscosity of the resin may increase due to an excessive amount of unreacted acid monomer, and the appearance of the coating film may deteriorate. When the mixing ratio exceeds the above range, the alkyd resin has a small molecular weight As a result, the drying rate is slowed down, and physical properties such as rust prevention and chemical resistance of the coating film may be deteriorated.

The alkyd resin may have an oil length of 45 to 65%, for example, 50 to 60%. When the oil length of the alkyd resin is less than the above range, the coating film becomes hard and bending resistance may be lowered, and when it exceeds the above range, the drying speed slows down and the workability may be lowered

The alkyd resin may have a non-volatile content of 60 to 75%, for example, 65 to 70%. When the non-volatile content of the alkyd resin is less than the above range, the solvent content in the paint is relatively high and may exceed the legal standard for volatile organic compounds (VOC). may slow down and reduce water resistance.

The alkyd resin may have a number average molecular weight of 2,000 to 9,000, for example, 3,000 to 8,000 g/mol, and a weight average molecular weight of 90,000 to 180,000, for example, 100,000 to 170,000 g/mol. When the number average molecular weight and the weight average molecular weight of the alkyd resin are less than the above-mentioned ranges, the drying speed is slowed and workability is lowered, and the density of the dry coating film is lowered to facilitate moisture permeation from the outside, so that rust prevention may be lowered. On the other hand, when the above-mentioned range is exceeded, the viscosity of the resin may increase and the smoothness of the coating film may decrease, and the viscosity of the paint may increase, resulting in a decrease in workability, and an additional solvent may be required, resulting in increased generation of volatile organic compounds (VOCs). .

The alkyd resin may be included in an amount of 20 to 50% by weight, for example, 30 to 40% by weight based on the total amount of the coating composition. If the content of the alkyd resin is less than the above range, the resin content forming the coating film is low, and overall physical properties such as paint adhesion, bending resistance, rust prevention, and water resistance may be deteriorated. If the content exceeds the above range, the surface of the coating film is smooth. This can reduce the adhesion of the subsequent paint and increase the price of the paint.

inorganic particulates

When iron on the surface of iron parts combines with oxygen, iron oxide is formed and corroded. The oxidation reaction of iron is catalyzed by contact with water or moisture and is accelerated in high temperature and acidic environments. Various studies have been made to prevent corrosion by suppressing the oxidation reaction of iron, and conventional paints containing heavy metal rust inhibitors such as Kwangmyeongdan (Pb ₃ O ₄ ) have been used. However, since heavy metals are harmful to workers' health and the environment, paints with low or no heavy metal content are required.

The coating composition of the present invention uses inorganic fine particles to impart excellent anti-rust properties to the coating without using heavy metals. The inorganic fine particles include a metal compound and a platy pigment.

The metal compound forms a passivated coating film together with the alkyd resin to suppress the oxidation reaction of iron. As the metal compound, zinc oxide, zinc phosphate, aluminum silicate, or a mixture thereof may be used.

As the metal compound, a particle size of 0.5 to 7 μm, for example, 1 to 5 μm may be used. When the particle size of the metal compound is less than the above range, the oil absorption increases, so the viscosity of the paint increases and the smoothness of the coating film may decrease. .

The metal compound may be included in an amount of 1 to 15% by weight, for example, 2 to 12% by weight based on the total amount of the coating composition. When the content of the metal compound is less than the above-mentioned range, the oxidation reaction of iron is insufficiently inhibited, and thus rust-preventive properties may be deteriorated. On the other hand, the metal compound does not show an additional oxidation reaction inhibitory effect despite the increase in the content above a certain amount. Therefore, when the content of the metal compound exceeds the above-mentioned range, rust-preventive properties are not further improved, but rather, the resin content is lowered, and thus physical properties such as bending resistance and coating film adhesion may be deteriorated.

The plate-shaped pigment plays a role of preventing moisture from penetrating into the coating film or minimizing contact with moisture by extending the movement path to the iron as much as possible even if moisture penetrates. As the plate-like pigment, talc, mica, aluminum, or a mixture thereof may be used.

As the plate-shaped pigment, a particle size of 3 to 25 μm, for example, 5 to 20 μm may be used. When the particle size of the plate-shaped pigment is less than the above range, oil absorption increases, so the viscosity of the paint increases and smoothness may decrease.

The plate-shaped pigment may be included in an amount of 5 to 35% by weight, for example, 10 to 30% by weight based on the total weight of the coating composition. If the content of the plate-like pigment is less than the above range, the content of the metal compound may be increased to achieve the effect of inhibiting the oxidation reaction of iron, and thus the price of the paint may increase, and if it exceeds the above range, rust-preventive properties may be deteriorated.

The mixing ratio (weight ratio) of the metal compound and the plate-shaped pigment may be 1:2 to 7. For example, the inorganic fine particles include zinc oxide and talc, and the mixing ratio (weight ratio) of zinc oxide and talc may be 1:2 to 7. The plate-shaped pigment serves to prevent moisture from coming into contact with the steel material. When the content of the plate-shaped pigment is reduced, moisture permeation may be facilitated along the surface of the spherical zinc oxide. Therefore, when the mixing ratio of the plate-shaped pigment to the metal compound is less than 2, rust-preventive properties may be deteriorated, and the price of the paint is also increased. On the other hand, since zinc oxide does not change in response to moisture and oxygen, it serves to prevent iron from being oxidized. Therefore, when the mixing ratio of the plate-like pigment to the metal compound exceeds 7, the content of zinc oxide is reduced, so that the oxidation reaction of the iron material is facilitated, and rust-preventive properties may be deteriorated.

In the coating composition of the present invention, the mixing ratio (weight ratio) of the alkyd resin and the inorganic fine particles may be 0.5 to 5:1. When the mixing ratio of the alkyd resin to the inorganic fine particles is less than 0.5, adhesion, bending resistance, and gloss properties may be deteriorated due to insufficient resin content, and when it exceeds 5, rust prevention may be deteriorated.

pigment

The coating composition of the present invention may further include a pigment in addition to the inorganic fine particles. As the pigment, a colored pigment, an extender pigment, or a mixture thereof may be used.

The colored pigment serves to impart color to the coating film, and any pigment known in the art may be used without particular limitation. Non-limiting examples of the color pigment include iron oxide, titanium oxide, carbon black, precipitated barium sulfate, calcium carbonate, kaolin, mica, aluminum, chromium oxide, cobalt aluminate, azo pigments, phthalocyanine pigments, and anthraquinone pigments. As the colored pigment, one having a particle size of 35 μm or less may be used.

The color pigment may be added to the paint composition within a range known in the art, for example, 4 to 10% by weight based on the total weight of the paint composition.

The extender pigment serves as a filler to improve the strength of the coating film, and can be used without particular limitation as long as it is known in the art. Non-limiting examples of the extender pigment include calcium carbonate, mica, Al ₂ O ₃ ·SiO ₂ , MgO · SiO ₂ and the like. As the extender pigment, those having a particle size of 5 μm or less may be used.

The extender pigment may be added to the paint composition within a range known in the art, for example, 10 to 30% by weight based on the total weight of the paint composition.

Other Ingredients

The coating composition of the present invention may further contain a solvent. The solvent serves to control the viscosity and drying speed of the coating composition, and is not particularly limited as long as it can be easily volatilized during drying of the coating film. An organic solvent can be used as the solvent, and examples of the organic solvent include mineral spirits, ketone-based solvents, ester-based solvents, ether-based solvents, hydrocarbon-based solvents, alcohol-based solvents, or mixtures thereof. The content of the solvent is not particularly limited, and may be the remaining amount adjusted so that the total amount of the coating composition is 100% by weight. For example, the solvent may be included in an amount of 1 to 20% by weight based on the total amount of the paint composition.

The paint composition of the present invention may include additives commonly used in the paint field within a range that does not impair the inherent characteristics of the composition. Non-limiting examples of additives usable in the present invention include a dispersing agent, a stabilizer, a bentone activator, an anti-settling agent, an anti-sagging agent, an anti-film agent, an antifoaming agent, a leveling agent, an amide wax, and a drying agent. The additives may be added to the paint composition in an amount known in the art, for example, 0.01 to 10% by weight based on the total weight of the paint composition.

The present invention will be described in more detail through the following examples. 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 sense.

[Example 1-9]

According to the composition shown in Table 1 below, the coating composition of each Example was prepared. The usage unit of each component in Table 1 below is parts by weight.

[Comparative Example 1-6]

According to the composition shown in Table 2 below, the coating composition of each comparative example was prepared. The usage unit of each component in Table 2 below is parts by weight.

Alkyd resin 1: Oil Length 54%, non-volatile matter 68%, number average molecular weight 3,500 g/mol, weight average molecular weight 100,000 g/mol

Alkyd resin 2: Oil Length 58%, non-volatile matter 68%, number average molecular weight 7,800 g/mol, weight average molecular weight 165,000 g/mol

Alkyd resin 3: Oil Length 75%, non-volatile matter 68%, number average molecular weight 7,500 g/mol, weight average molecular weight 160,000 g/mol

Alkyd resin 4: Oil Length 65%, non-volatile matter 65%, number average molecular weight 9,500 g/mol, weight average molecular weight 200,000 g/mol

Acrylic modified alkyd resin: Oil Length 60%, non-volatile content 65%, number average molecular weight 6,500 g/mol, weight average molecular weight 50,000 g/mol

Metal compound 1: Zinc oxide (particle size 4 μm)

Metal compound 2: zinc phosphate (particle size 3 μm)

Plate-shaped pigment 1: talc (particle size 16 μm)

Plate-shaped pigment 2: mica (particle size 12 μm)

Color pigment: iron oxide (red-brown pigment)

Extender Pigment: Calcium Carbonate (5CN, Omiya)

Dispersant: Anti-Terra 203 (BYK)

Antisettling agent: Bentone (Claytone 40, BYK)

Bentone activator: EFKA FA 4644 (BASF)

Amide Wax: HPA-220X (excitable)

Film inhibitor: Methyl Ethyl Ketonxime

Leveling agent: BYK 320 (BYK)

Defoamer: HS-69 (excitable)

Desiccant 1: Co-Naphthanate 10% (true positive)

Desiccant 2: Ca-Naphthanate 4% (true positive)

[Evaluation of physical properties]

After measuring the physical properties of the coating composition prepared according to each Example and Comparative Example according to the following method, the results are shown in Tables 3 and 4 below.

Viscosity (25 ℃)

It was measured using a STORMER viscometer.

Polished (60°)

According to ASTM D523, it was measured at 60° using a Gloss Meter (BYK).

dryness to the touch

After applying the coating composition of each Example and Comparative Example to a thickness of 11-16 μm on a glass plate, the time point at which the coating film did not come off when touched with a finger while drying at a temperature of 25 ° C. was measured.

hardening dryness

The test plate was clamped between the thumb and the thumb, and the coating film was pressed with force (do not twist) close to the thumb, and the time point at which fingerprint marks were not formed on the coating film was measured.

sagging resistance

After diluting the coating composition of each Example and Comparative Example to a volume ratio of 20%, it was applied on the glass according to the coating film thickness using a sagging resistant applicator. Immediately after application, the thickness of the coating film that did not flow down when standing vertically was measured.

corrosion peeling

According to KSM6030:2019, the degree of peeling was measured after 21 days.

Top coat suitability

Top coat suitability was measured by a winkle test according to KSM6030:2019.

adhesiveness

According to TEST METHOD B of ASTM D3359, draw lines vertically and horizontally with a sharp knife on the dried coating film to make 100 grids, attach cellophane tape, rub it, pull the tape strongly upward, and check whether the coating film is peeling off. evaluated.

heat storage

After the coating compositions of each Example and Comparative Example were allowed to stand at 60 ° C. for 7 days, layer separation, precipitation, and viscosity change were observed.

Workability

The coating compositions of each Example and Comparative Example were diluted with thinner to a volume ratio of 20%, applied using a roller and a spray gun, and then it was evaluated whether a well-smooth coating film was formed.

As confirmed from the results of Table 3, the paint compositions of Examples 1-9 according to the present invention exhibited excellent physical properties in all measured physical properties. On the other hand, as confirmed from the results of Table 4, the paint compositions of Comparative Examples 1-5 that deviated from the composition according to the present invention exhibited inferior physical properties compared to the paints of Examples.

Specifically, the coating compositions of Comparative Examples 1 and 2 using the alkyd resin outside the range of physical properties according to the present invention showed a slow drying rate, severe corrosion occurred in the coating film formed with the coating composition, and topcoat compatibility, heat Storage and workability were also poor. The coating compositions of Comparative Examples 3 and 4 using only one of a metal compound and plate-shaped pigment as inorganic fine particles and Comparative Example 5 without using inorganic fine particles showed a slow drying rate, and a severe degree of corrosion was observed in the coating film formed of the coating composition. occurred, and top coat suitability, heat storage property, and workability were also poor. The coating composition of Comparative Example 6 to which the acrylic-modified alkyd resin was applied exhibited a slow drying rate, severe corrosion occurred in the coating film formed of the coating composition, and poor top coat compatibility, heat storage performance, and workability.

Claims (5)

containing an alkyd resin and inorganic fine particles;
The alkyd resin has an oil length of 45 to 65%, a non-volatile content of 60 to 75%, a number average molecular weight of 2,000 to 9,000 g / mol, and a weight average molecular weight of 90,000 to 180,000 g / mol,
The inorganic fine particles include a metal compound and a platy pigment,
A coating composition wherein the mixing ratio (weight ratio) of the metal compound and the plate-like pigment is 1:2 to 7. The coating composition of claim 1, wherein the metal compound has a particle size of 0.5 to 7 μm. The coating composition according to claim 1, wherein the plate-shaped pigment has a particle size of 3 to 25 μm. delete The paint composition according to claim 1, comprising 20 to 50% by weight of the alkyd resin, 1 to 15% by weight of the metal compound, and 5 to 35% by weight of the plate-like pigment, based on the total weight of the paint composition.