Method for manufacturing an iron rust reduction rust inhibitor.

Abstract

To provide a two-liquid type iron rust-reducing rustproofing agent that enables a coating to be performed without removing rust generated in a steel substrate when applying the coating to solve the following problems: conventional one-liquid type iron rust-reducing rustproofing agent has poor penetration into the red rust layer generated on steel substrates, resulting in a slow conversion or reduction reaction of red or brown rust (Fe2O3) to black rust (magnetite: Fe3O4) and incomplete or inadequate conversion to black rust; and also in the case of the one-liquid type, the polymerization reaction of the contained water-soluble resin emulsion progresses gradually after long-term storage, which increases the viscosity of the rust inhibitor and further reduces its ability to penetrate the iron rust layer.SOLUTION: Provided is not a conventional one-liquid type iron rust-reducing rustproofing agent, but a two-liquid type iron rust-reducing rustproofing agent that enables a coating to be formed without removing rust generated in a steel substrate when applying the coating. A rustproofing agent (agent A) to be applied at the beginning is free of emulsion resins and contains a lower alcohol having 5 or less carbon atoms. Thus, the viscosity of the rustproofing agent (agent A) is greatly lowered, and it is possible to significantly improve permeability to iron rust layers. As a result, it becomes possible to cause progression of a conversion reaction of red rust and brown rust (Fe2O3) to black rust (magnetite: Fe3O4) with certainty throughout the entire application surface. An iron rust-reducing rustproofing agent (agent B) applied subsequent to the iron rust-reducing rustproofing agent (agent A) contains an aqueous emulsion and a lower alcohol having not more than 5 carbon atoms, exhibits fine permeability to the iron rust-reducing rustproofing agent (agent A), and can simultaneously promote the conversion reaction of red rust and brown rust (Fe2O3) to black rust (magnetite: Fe3O4) and enhance the waterproofing property, the corrosion resistance, the durability, and the rust-proofing ability of a coating film.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to the technical field of pretreatment for rust prevention in the pretreatment before painting on steel substrates such as steel and stainless steel. By applying it to the surface of a steel substrate, it can reduce the generated red rust and brown rust: Fe2O3 to black rust: Fe3O4, and it relates to a rust reduction and rust prevention treatment agent that also serves as a pretreatment for painting that can be painted without mechanically removing iron rust.

Background Art

[0002] When painting a steel substrate, if the iron rust generated on the surface is not removed, the expansion of the iron rust layer due to the progress of steel oxidation, the deterioration of the coating film, and the peeling of the coating film due to the decrease in adhesion have occurred. Therefore, when painting a steel substrate, the iron rust generated on the steel substrate must be pretreated by mechanical removal such as sandpaper, wire brushing, and sandblasting. This pretreatment of the substrate before painting requires a great deal of labor, and there has been a strong demand for reducing this pretreatment of the substrate. As a countermeasure, it has been proposed to mix phosphoric acid, zinc phosphate, and other phosphate compounds into the primer paint. However, the permeability and reducing power inside the iron rust are small, and it is not satisfactory in terms of the rust prevention property and durability of the coating film. Prior Patent Documents

[0003] JP-A-2004-338236 JP-A-2005-105337 JP-A-2009-40929

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present invention relates to a rust reduction and rust prevention treatment agent that, in the pretreatment before painting on a steel substrate, directly applies a pretreatment coating agent to the steel substrate without performing a conventional mechanical iron rust removal operation, so that the reducing substance in the paint penetrates into the iron rust and reacts with the red or brown iron rust to convert it into black rust. At the same time, it forms a rust prevention coating film having excellent rust prevention property, water resistance, and weather resistance. [Means for solving the problem]

[0005] The first invention of the present invention is a two-component rust reduction and rust prevention treatment agent for paint on steel substrates, characterized in that it comprises a rust reduction and rust prevention treatment agent (Agent A) characterized by being formulated with a reducing mineral acid, tannic acid, and alcohols with 5 or fewer carbon atoms as reducing substances to reduce the rust on the substrate, and a rust reduction and rust prevention treatment agent (B) consisting of a water-soluble emulsion resin and lower alcohols with 5 or fewer carbon atoms applied to the rust layer of the steel plate beneath the coating film to which Agent A has been applied, in order to promote the conversion to black rust and the reduction reaction. By formulating Agent A with alcohols with 5 or fewer carbon atoms, the components of reducing phosphoric acid and tannic acid have high penetration into the rust layer and also have excellent reduction reactivity with rust. Furthermore, by applying Agent B, the reduction reaction of rust (red rust and brown rust: Fe2O3) is further promoted, and the conversion to black rust (magnetite: Fe3O4) proceeds more completely, forming a coating film with high rust prevention ability and corrosion resistance.

[0006] The second invention of the present invention relates to a pre-treatment agent for a steel substrate used in painting, wherein hypophosphorous acid and phosphorous acid are preferred as reducing mineral acids contained as reducing substances for iron rust in the iron rust reduction rust prevention agent (Agent A), as they exhibit excellent reducing reactivity towards iron rust, and the combination of hypophosphorous acid and phosphorous acid is particularly preferred. The present invention relates to the two-component iron rust reduction rust prevention agent of the present invention, characterized in that the iron rust reduction rust prevention agent (Agent A) contains at least one of hypophosphorous acid and phosphorous acid.

[0007] The third invention of the present invention has found that, in a pre-treatment agent for coating steel substrates, it is even more preferable, in terms of the reducing properties and durability of the coating film, to further incorporate a reducing phosphate compound (a compound with reducing phosphates such as zinc, aluminum, and calcium) along with a reducing mineral acid.

[0008] The fifth invention of this invention is a rust prevention treatment method for a steel substrate, in which a rust reduction rust prevention treatment agent (Agent A), which reduces iron rust on the steel substrate to prevent rust, and a rust reduction rust prevention treatment agent (Agent B), which further promotes the reduction reaction of iron rust, are applied to the substrate in two layers and two stages. This method is found to be superior in terms of the rust prevention ability, waterproofing, and corrosion resistance of the coating film. [Effects of the Invention]

[0009] The present invention's iron rust reduction rust-preventive treatment agent does not require any pre-treatment work to remove iron rust from the substrate. By applying the two-component iron rust reduction rust-preventive treatment agent to a substrate surface where iron rust has occurred, red rust is converted to black rust, forming a black rust-preventive and waterproof coating. Therefore, it can be used as is, like ordinary paint, but a topcoat may also be applied.

[0010] Furthermore, this two-component iron rust reduction rust-preventive treatment agent has high penetration into the oxide film and iron rust layer of steel substrates, resulting in high rust prevention and waterproofing capabilities. Therefore, when applying a topcoat, it is possible to enhance the durability of the topcoat film. The use of this two-component iron rust reduction rust inhibitor eliminates the need for pretreatment work to remove iron rust from steel substrates, significantly reducing the amount of painting work. Furthermore, the durability of the coating is greatly improved, resulting in a substantial reduction in painting and maintenance costs for the target substrates. [Modes for carrying out the invention]

[0011] In the present invention, the reducing mineral acid in the iron rust reduction rust-preventive treatment agent (Agent A), which has the function of reducing iron rust (red rust, brown rust), is a reducing phosphoric acid and its compounds, which have high rust-preventive capabilities. Phosphorous acid and hypophosphorous acid are particularly preferred. These reducing phosphoric acid-based mineral acids react with iron rust to reduce iron oxide and also react with steel substrates to form reduced iron phosphate, thereby exhibiting rust prevention. The blending ratio of reducing phosphoric acid-based mineral acids is preferably 0.5 to 30% by weight in the paint. If the blending amount of reducing phosphoric acid-based mineral acids is less than 0.5% by weight, the rust prevention performance decreases, and if it exceeds 30% by weight, the coating film strength and water resistance decrease.

[0012] Regarding the reducing mineral acid in the above-mentioned iron rust reduction rust inhibitor (Agent A), reducing phosphoric acid may be added along with reducing phosphoric acid, or reducing phosphoric acid compounds may be added to enhance rust prevention ability. Preferred reducing phosphoric acid compounds include iron phosphate, calcium phosphate, magnesium phosphate, aluminum phosphate, iron hypophosphate, calcium hypophosphate, magnesium hypophosphate, and aluminum hypophosphate. It is preferable to include these reducing phosphoric acid compounds in the iron rust reduction rust inhibitor (Agent A) at a concentration of 0.5 to 20% by weight.

[0013] The tannic acid used in the iron rust reduction rust-preventive treatment agent (Agent A) in this invention can be persimmon tannin, bark extracts of acacia mangium radiata pine, etc., but it is preferable to use tannic acid extracted and purified from gallnuts. The amount of tannic acid in the iron rust reduction rust-preventive treatment agent (Agent A) is preferably 1 to 30% by weight. If the amount of tannic acid is less than 1% by weight, adhesion to rust and rust prevention will decrease. If it exceeds 30% by weight, water resistance and coating performance will decrease significantly.

[0014] In the present invention, the iron rust reduction rust-preventive treatment agent (Agent A) preferably contains a lower alcohol with 5 or fewer carbon atoms to enhance the penetration of tannic acid and reducing phosphoric acid compounds. Examples of lower alcohols with 5 or fewer carbon atoms include methanol, ethyl alcohol, propanol, butanol, and pentanol, with ethanol and n-propanol being particularly preferred in terms of penetration and safety. The amount of alcohol with 5 or fewer carbon atoms is 1 to 50% by weight, and a concentration of 10 to 40% by weight is particularly desirable in terms of penetration and coating film strength.

[0015] In the present invention, the water-soluble emulsion resin to be contained in the iron rust reduction rust prevention agent (Agent B), which is used to promote the reduction reaction and enhance the waterproofness of the coating film after application of the iron rust reduction rust prevention agent (Agent A), can be acrylic resin emulsion, acrylic-vinyl acetate resin emulsion, acrylic-ethylene vinyl acetate resin emulsion, acrylonitrile-vinyl chloride-vinylidene chloride copolymer emulsion, acrylic urethane resin emulsion, acrylic epoxy resin emulsion, acrylic silicone resin emulsion, etc., and these can be used.

[0016] For the water-soluble emulsion resin used in the iron rust reduction rust inhibitor (Agent B), acrylic resin emulsion, acrylic urethane resin emulsion, and acrylic silicone resin emulsion are particularly preferred due to their ease of film formation, penetration into rust, and ease of application. These resins may be used individually or in combination of two or more. The amount of water-soluble emulsion resin in the paint is used in the range of 10 to 95% by weight, but a blend of 30 to 80% by weight is particularly preferred in terms of iron rust reduction reactivity, rust prevention ability, and paint film strength.

[0017] In the present invention, it is desirable to include a lower alcohol with 5 or fewer carbon atoms in the iron rust reduction rust-preventive treatment agent (Agent B). Examples of lower alcohols with 5 or fewer carbon atoms include methanol, ethyl alcohol, propanol, butanol, and pentanol, with ethanol and n-propanol being particularly preferred in terms of penetration and safety. The amount of alcohol with 5 or fewer carbon atoms included is 1 to 40% by weight, and a blend of 10 to 30% by weight is particularly desirable in terms of penetration and coating film strength.

[0018] The water-based rust-preventive paint of the present invention may contain various known paint additives to improve paint properties (viscosity, gloss, drying speed, film strength, water resistance, etc.) as needed. For example, paint additives such as dispersants like surfactants, leveling agents, viscosity modifiers, plasticizers, crosslinking agents, film-strengthening fillers, and coloring pigments may be added.

[0019] The iron rust reduction and rust prevention treatment agent (Agent A) of the present invention is formulated with a reducing phosphoric acid-based mineral acid, tannic acid, and a lower alcohol having 1 to 5 carbon atoms as raw materials. Also, the iron rust reduction and rust prevention treatment agent (Agent B) is mainly formulated with a water-soluble emulsion, water, and a lower alcohol having 1 to 5 carbon atoms as raw materials, and can be produced by mixing and dispersing them with a wet disperser. Since the iron rust reduction and rust prevention treatment agent of the present invention is water-based, it can be appropriately diluted with pure water as needed to adjust the concentration and viscosity.

[0020] The iron rust reduction and rust prevention treatment agent of the present invention can be applied to the surface of the steel substrate to be coated without removing the rust layer generated on the surface of the steel substrate. That is, topcoat painting can be performed without performing substrate preparation (pickling), which is a pretreatment for steel substrates, reducing the rust layer of the substrate, and forming a coating film excellent in rust prevention, corrosion resistance, weather resistance, and adhesion is characteristic.

[0021] That is, by applying the iron rust reduction and rust prevention treatment agent (Agent A), the reducing phosphoric acid-based mineral acid contained therein converts the red rust or brown rust (Fe2O3) of iron generated on the steel substrate to be coated into black rust (magnetite: Fe3O4) by a reduction reaction, and at the same time reacts with the steel substrate to form a reducing iron phosphate film with high rust prevention ability on the steel surface, which is the interface with the coating film. Furthermore, by applying the iron rust reduction and rust prevention treatment agent (Agent B), the water-based emulsion contained therein promotes the conversion reaction of iron rust to black rust (magnetite: Fe3O4) and the polymerization and cross-linking reaction of the water-based emulsion, and can significantly improve the black rust conversion and adhesion from the iron rust reduction reaction of the coating film, thereby making it possible to form a rust prevention coating film excellent in water resistance, corrosion resistance, and weather resistance.

[0022] Also, for the above reasons, the iron rust reduction reaction water-based rust prevention paint of the present invention can exhibit excellent rust prevention and corrosion protection properties compared to ordinary iron oxide (red iron oxide) - based primer paints for new steel substrates and steel structures without rust.

Example

[0023] The present invention will be specifically described below based on examples, but the present invention is not limited thereto.

Example

[0024] As the iron rust reduction and rust prevention treatment agent (Agent A), phosphorous acid: 50 g, tannic acid: 150 g, ethanol: 150 g, n-propanol: 50 g, and pure water: 600 g were put into a wet disperser and mixed and dispersed to obtain the water-based rust prevention paint (Agent A) of Example 1. The blending ratio of this raw material is shown in Table 1.

[0025] As the iron rust reduction and rust prevention treatment agent (Agent B), acrylic resin emulsion (AP1350 manufactured by Showa High Polymer Co., Ltd.): 650 parts by weight, ethanol: 100 g, n-propanol: 50 g, and pure water: 200 g were added to a wet disperser and mixed and dispersed to obtain the water-based rust prevention paint (Agent B) of Example 1. The blending ratio of this raw material is shown in Table 2.

[0026] To the rusted steel plates (4 kinds of pickled products) with floating rust removed, this water-based rust prevention paint (Agent A) and (Agent B) were applied at 100 g / m each as the coating amount. 2 And left to stand and dry at 25 °C for 5 days to obtain test pieces for evaluation.

[0027] As an evaluation test of the coated test pieces, a salt spray resistance test and an accelerated weather resistance test were carried out. In the salt spray resistance test, the test pieces were immersed in warm water at 50 °C for 1000 hours, then taken out and the presence or absence of abnormalities in the appearance of the coating film was observed, and a cross-cut tape peeling test was also carried out. Furthermore, in the accelerated weather resistance test, treatment was carried out for 3000 hours with a sunshine weatherometer tester, and the subsequent coating film condition was observed. The results are shown in Table 4.

Example

[0028] As the iron rust reduction and rust prevention treatment agent (Agent A), calcium phosphite: 50 g, tannic acid: 150 g, ethanol: 150 g, n-propanol: 50 g, and pure water: 600 g were added to a wet disperser and mixed and dispersed to obtain the water-based rust prevention paint (Agent A) of Example 2. This blending table is shown in Table 1.

[0029] As the iron rust reduction rust-preventive treatment agent (Part B), 650 parts by weight of acrylic resin emulsion (AP1350, manufactured by Showa Polymer Co., Ltd.), 100 g of ethanol, 50 g of n-propanol, and 200 g of pure water were added to a wet disperser and mixed and dispersed to obtain the water-based rust-preventive paint (Part B) of Example 2. The mixing ratio of these raw materials is shown in Table 2.

[0030] The two-component water-based rust-preventive coating obtained in Example 2 was applied to test pieces in which iron rust had been induced, in the same manner as in Example 1. Saltwater resistance tests and accelerated weathering tests were then performed on this rust-preventive coating film in the same manner as in Example 1. The measurement results are shown in Table 4. [Examples]

[0031] As an iron rust reduction rust inhibitor (Agent A), 50g of aluminum phosphate, 150g of tannic acid, 150g of ethanol, 50g of n-propanol, and 600g of pure water were added to a wet disperser and mixed and dispersed to obtain the water-based rust inhibitor paint (Agent A) of Example 3. The mixing ratio of these raw materials is shown in Table 1.

[0032] As the iron rust reduction rust-preventive treatment agent (Part B), 650 parts by weight of acrylic silicone resin emulsion (Nisshin Chemical Co., Ltd. E430), 100 g of ethanol, 50 g of n-propanol, and 200 g of pure water were added to a wet disperser and mixed and dispersed to obtain the water-based rust-preventive paint (Part B) of Example 3. The formulation table is shown in Table 2.

[0033] The two-component water-based rust-preventive coating obtained in Example 3 was applied to test pieces in which iron rust had been induced, in the same manner as in Example 1. Saltwater resistance tests and accelerated weathering tests were then performed on this rust-preventive coating film in the same manner as in Example 1. The measurement results are shown in Table 4. [Examples]

[0034] As an iron rust reduction rust inhibitor (Agent A), 50g of hypophosphorous acid, 150g of tannic acid, 150g of ethanol, 50g of n-propanol, and 600g of pure water were added to a wet disperser and mixed and dispersed to obtain the water-based rust inhibitor paint (Agent A) of Example 4. The mixing ratio of these raw materials is shown in Table 1.

[0035] As the iron rust reduction rust-preventive treatment agent (Part B), 650 parts by weight of acrylic resin marion (AP1350, manufactured by Showa Polymer Co., Ltd.), 100 g of ethanol, 50 g of n-propanol, and 200 g of pure water were added to a wet disperser and mixed and dispersed to obtain the water-based rust-preventive paint (Part B) of Example 4. The formulation table is shown in Table 2.

[0036] The two-component water-based rust-preventive coating obtained in Example 4 was applied to test pieces in which iron rust had been induced, in the same manner as in Example 1. Saltwater resistance tests and accelerated weathering tests were then performed on this rust-preventive coating film in the same manner as in Example 1. The measurement results are shown in Table 4. [Examples]

[0037] As an iron rust reduction rust inhibitor (Agent A), 50g of calcium hypophosphite, 150g of tannic acid, 150g of ethanol, 50g of n-propanol, and 600g of pure water were added to a wet disperser and mixed and dispersed to obtain the water-based rust inhibitor paint (Agent A) of Example 5. The mixing ratio of these raw materials is shown in Table 1.

[0038] As the iron rust reduction rust-preventive treatment agent (Part B), 650 parts by weight of acrylic silicone resin emulsion (Nisshin Chemical Co., Ltd. E430), 100 g of ethanol, 50 g of n-propanol, and 200 g of pure water were added to a wet disperser and mixed and dispersed to obtain the water-based rust-preventive paint (Part B) of Example 5. The formulation table is shown in Table 2.

[0039] The two-component water-based rust-preventive coating obtained in Example 5 was applied to test pieces in which iron rust had been induced, in the same manner as in Example 1. Saltwater resistance tests and accelerated weathering tests were then performed on this rust-preventive coating film, in the same manner as in Example 1. The measurement results are shown in Table 4. Comparative Example

[0040] The following are comparative examples. Comparative Example 1

[0041] Acrylic resin emulsion (AP1350, manufactured by Showa Polymer): 650 parts by weight, phosphoric acid: 50 g, tannic acid: 150 g, and pure water: 250 g were added to a wet disperser and mixed and dispersed to obtain the water-based rust-preventive paint (one-component type) of Comparative Example 1. The formulation table is shown in Table 3. Then, similar to Example 1, this water-based rust-preventive paint (one-component type) was applied to a rusted steel plate (Type 4 surface treatment) from which surface rust had been removed, at a coating rate of 100 g / m². 2 The coating was applied and allowed to stand and dry at 25°C for 5 days to prepare the test specimens for evaluation. The applied coating was evaluated in the same manner as in Example 1, and the measurement results are shown in Table 5. Comparative Example 2

[0042] Comparative Example 2, a water-based rust-preventive coating (one-component type), was prepared by blending 650 parts by weight of acrylic resin emulsion (AP1350, manufactured by Showa Polymer), 150 parts by weight of tannic acid, 50 parts by weight of calcium phosphate, and 250 parts by weight of pure water. The coating film was then evaluated in the same manner as in Example 1, and the measurement results are shown in Table 5. Comparative Example 3

[0043] Acrylic silicone resin emulsion (AP1350, manufactured by Showa Polymer): 650 parts by weight, tannic acid: 150 parts by weight, aluminum phosphate: 50 parts by weight, and pure water: 250 parts by weight were added and mixed and dispersed to obtain Comparative Example 3, a water-based rust-preventive paint (one-component type). The coating film was then evaluated in the same manner as in Example 1, and the measurement results are shown in Table 5.

[0044] [Table 1]

[0045] [Table 2]

[0046] [Table 3]

[0047] [Table 4]

[0048] [Table 5]

Claims

1. A rust-reducing rust-preventive treatment agent (Agent A) for pre-treatment of iron rust in painting on steel substrates, characterized in that it contains a reducing substance that reduces iron rust on the substrate, a reducing phosphoric acid-based mineral acid, and further tannic acid and alcohols with 5 or fewer carbon atoms, A rust reduction and rust prevention treatment agent (Agent B) containing a water-soluble emulsion resin and a lower alcohol with 5 or fewer carbon atoms, wherein the amount of the water-soluble emulsion resin is in the range of 30 to 80% by weight, thereby enhancing the waterproofness of the coating film and further promoting the reduction reaction of iron rust in the layer beneath the applied coating film, A two-component iron rust reduction rust prevention treatment agent characterized by being applied by coating.

2. The two-component iron rust reduction and rust prevention agent according to claim 1, characterized in that the reducing phosphoric acid mineral acid as the iron rust reducing substance in the iron rust reduction and rust prevention agent (Agent A) contains at least one of hypophosphorous acid and phosphorous acid.

3. A two-component iron rust reduction and rust prevention agent according to claim 1 or 2, characterized in that, as a component of the iron rust reduction and rust prevention agent (Agent A), a reducing phosphoric acid-based mineral acid is combined with a reducing phosphoric acid compound, and the reducing phosphoric acid compound contains at least one compound of reducing phosphoric acid of zinc, aluminum, and calcium.

4. A two-component iron rust reduction and rust prevention agent according to any one of claims 1 to 3, characterized in that the iron rust reduction and rust prevention agent (agent B) is formulated with at least one of acrylic emulsion and acrylic silicone emulsion as the water-soluble emulsion resin.

5. A rust prevention treatment method characterized by applying two layers of a rust-reducing rust-preventive treatment agent (Agent A), which reduces iron rust on the steel substrate to prevent rust, and a rust-reducing rust-preventive treatment agent (Agent B), which further promotes the reduction reaction of iron rust, to the substrate in a pretreatment of a steel substrate, wherein the rust prevention treatment is performed using a two-component rust-reducing rust-preventive treatment agent according to any one of claims 1 to 4.

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