Water-based metal roof rust conversion coating and preparation method thereof

Abstract

The invention provides a water-based metal roof rust conversion coating and a preparation method thereof, and the water-based metal roof rust conversion coating comprises the following components by weight: 10-40 parts of deionized water; 3-10 parts of antirust pigment and filler; 1-5 parts of a rust conversion agent; 0.5-2 parts of a penetrant; 50 to 70 parts of epoxy modified styrene-acrylic emulsion; 0.5 to 2.6 parts of a first auxiliary agent; and 3.6 to 10.5 parts of a second auxiliary agent. The rust conversion agent and the penetrating agent are introduced into the water-based metal roof rust conversion coating provided by the invention, and the epoxy modified styrene-acrylic emulsion is selected as a main raw material, so that the rust conversion coating not only has excellent comprehensive properties (such as excellent adhesion, weather resistance, salt spray resistance and the like), but also has excellent rust conversion and rust prevention effects.

Description

Technical Field

[0001] The invention belongs to the technical field of coatings and relates to a water-based metal roof rust-removing coating and a preparation method thereof. Background Art

[0002] Metal roofing refers to a roofing form that uses metal sheets as roofing materials, combining the structural layer and the waterproof layer into one. There are many types of metal sheets, including galvanized sheets, aluminum-zinc sheets, aluminum alloy sheets, aluminum-magnesium alloy sheets, titanium alloy sheets, copper sheets, stainless steel sheets, etc.

[0003] In order to protect metal roofs from corrosion and extend their service life, anti-corrosion coating of metal roofs has become the most economical and effective method. In order to obtain excellent corrosion resistance, the rust on the steel must be removed before painting, otherwise the paint film and anti-corrosion effect will be very poor due to the continuous expansion of rust. Therefore, rust removal is an important part of the coating process and plays a decisive role in the success or failure of anti-corrosion coating.

[0004] During the maintenance of metal roofs, due to the limitations of construction conditions, it is difficult to use mechanized construction methods. Rust removal can only be done by hand or electric tools, which will inevitably leave rust and various corrosion products, making it difficult to ensure the quality of rust removal, difficult construction, and huge costs. Therefore, it is very necessary to prepare rust-removing coatings that can be directly applied on the rust surface.

[0005] CN103173757A discloses a rust conversion agent and a preparation method thereof. The main components of the conversion agent are pyrogallic acid and tannic acid. Although the disadvantages of uneven coating and poor water resistance are solved, the conversion speed is slow and the rust removal is incomplete due to the low effective content of the conversion agent.

[0006] Therefore, it is desirable in the art to develop a rust-removing coating having a better rust-removing effect. Summary of the invention

[0007] In view of the deficiencies in the prior art, the object of the present invention is to provide a water-based metal roof rust-removing coating and a preparation method thereof.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a water-based metal roof rust-removing paint, wherein the water-based metal roof rust-removing paint comprises the following components in parts by weight:

[0010]

[0011] The present invention introduces a rust-removing agent and a penetrant into the provided water-based metal roof rust-removing paint, and selects epoxy-modified styrene-acrylic emulsion as the main raw material, so that the rust-removing paint not only has excellent comprehensive performance (such as excellent adhesion, weather resistance, salt spray resistance and the like), but also has excellent rust-removing and rust-preventing effects.

[0012] In the present invention, the water-based metal roof rust-removing paint can be used in an amount of deionized water of 10 parts, 12 parts, 14 parts, 16 parts, 18 parts, 20 parts, 22 parts, 24 parts, 26 parts, 28 parts, 30 parts, 32 parts, 34 parts, 36 parts, 38 parts, 40 parts, etc., by weight.

[0013] In the present invention, the amount of the anti-rust pigment and filler in the water-based metal roof rust-removing paint can be 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, etc., by weight.

[0014] In the present invention, the water-based metal roof rust-removing paint can be used in an amount of 1 part, 2 parts, 3 parts, 4 parts, 5 parts, etc., of the rust-removing agent in parts by weight.

[0015] In the present invention, the amount of the water-based metal roof rust-removing paint, measured by weight, the amount of the penetrant can be 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1 parts, 1.1 parts, 1.2 parts, 1.3 parts, 1.4 parts, 1.5 parts, 1.6 parts, 1.7 parts, 1.8 parts, 1.9 parts, 2 parts, etc.

[0016] In the present invention, the amount of the epoxy-modified styrene-acrylic emulsion in the water-based metal roof rust-removing paint can be 50 parts, 52 parts, 54 parts, 56 parts, 58 parts, 60 parts, 62 parts, 64 parts, 66 parts, 68 parts, 70 parts, etc., calculated by weight.

[0017] In the present invention, the amount of the first auxiliary agent in the water-based metal roof rust-reducing paint can be 0.5 parts, 1 parts, 1.5 parts, 2 parts, 2.5 parts, 2.6 parts, etc., by weight.

[0018] In the present invention, the amount of the second auxiliary agent in the water-based metal roof rust-removing paint can be 3.6 parts, 4 parts, 4.5 parts, 5 parts, 5.5 parts, 6 parts, 6.5 parts, 7 parts, 7.5 parts, 8 parts, 8.5 parts, 9 parts, 9.5 parts, 10 parts, 10.5 parts, etc., by weight.

[0019] Preferably, the anti-rust pigment filler includes any one of mica iron oxide red, zinc phosphate, aluminum dihydrogen tripolyphosphate, zinc yellow, zinc oxide, talcum powder, and barium sulfate, or a combination of at least two thereof.

[0020] Preferably, the rust-removing agent includes sodium bisulfate (NaHSO4). The present invention uses sodium bisulfate (NaHSO4) as the rust-removing agent, and when used, it does not need to go through the pre-coating treatment process of sandblasting and polishing, and can be directly coated with rust and oil.

[0021] Preferably, the penetrant includes sodium oleyl methyl taurate. As the penetrant enters the interior of the rust and reaches the substrate directly, a tight wrapping layer is formed to seal the rust, dissolving the rust, transforming the rust, and stabilizing the rust, thereby achieving the dual purpose of transforming the rust and preventing the rust, so that the rust will not return to rust for a long time in the atmosphere. The coating can transform the rust thickness of more than 50 μm, and is a fast, efficient, economical, environmentally friendly product with broad application prospects.

[0022] Preferably, the epoxy-modified styrene-acrylic emulsion is an epoxy-modified styrene-acrylic liquid emulsion produced by Senjie Chemical, which combines the advantages of high strength, corrosion resistance and strong adhesion of epoxy resin, while also retaining the weather resistance and good gloss of styrene-acrylic emulsion. This emulsion exhibits excellent film hardness, pollution resistance and water resistance in coating applications.

[0023] In the present invention, by adding a rust-removing agent, a penetrant, and an epoxy-modified styrene-acrylic emulsion, the coating has both good comprehensive properties and excellent rust-removing effect, as follows:

[0024] 1) Adding a rust remover: The rust remover is sodium bisulfate (NaHSO4). Metal corrosion mainly includes chemical corrosion and electrochemical corrosion, among which electrochemical corrosion is the focus of research. Since steel contains iron and carbon elements and various impurities, the surface of the steel is electrochemically unstable. Once it comes into contact with the solution, an electrochemical reaction will occur. At this time, the steel becomes a primary battery with iron as the anode and impurities as the cathode. The electrochemical reaction equation is as follows: Anode: Fe→Fe 2+ +2e - ; Cathode: 2H + +2e - →2H→H2 (hydrogen evolution reaction in acidic solution); O2+4H + +4e - →2H2O (acidic solution reduction reaction); O2+2H2O+4e - →4OH -(neutral medium reduction reaction); the overall reaction formula is: Fe+2H2O→Fe(OH)2+H2↑. The present invention solves the rust removal problem by using the cathode treatment method of hydrogen evolution reaction; 2) Sodium oleylmethyl taurate is added. As a penetrant, it can penetrate the rust-removing agent into the porous rust inner layer from the source of rust, so that it is converted from an active substance into a stable passivation sealing layer with protective function, so that the active rust becomes a stable filler. While reducing labor intensity, it also reduces costs and does no harm to the environment and human body. 3) The emulsion uses epoxy-modified styrene-acrylic emulsion, which grafts epoxy resin with styrene-acrylic emulsions of different molecular weights through polymerization reaction, thereby improving the particle size distribution, morphology and water resistance of the emulsion. This modified emulsion not only improves the hardness and adhesion of the coating, but also reduces the water absorption rate, showing excellent comprehensive performance.

[0025] Preferably, the first auxiliary agent includes any one of a dispersant, a mildew preventer, a defoamer, and a cellulose thickener, or a combination of at least two of them.

[0026] Preferably, the first auxiliary agent includes 0.1-1.0 part of a dispersant, 0.1-0.5 part of a mildew preventer, 0.1-0.6 part of a defoamer, and 0.2-0.5 part of a cellulose thickener.

[0027] Preferably, the dispersant includes a product produced by France's Coatex Company, with the brand name P30, a universal polycarboxylate sodium salt pigment and filler dispersant, which has special effects on various ultra-fine pigments and fillers and exhibits relatively stable dispersibility to ensure a relatively low effective dispersion viscosity at a higher pigment and filler content.

[0028] Preferably, the mildew inhibitor includes a product of Hikmais Company, the brand of which is CDT, components: carbendazim 9%, diuron 20%, OIT 3%.

[0029] Preferably, the defoamer comprises a mineral oil defoamer from Hairun Chemical, which is a grayish white to light yellow turbid liquid, a standard defoamer with a pigment volume concentration ranging from 20% to 70%, and contains a small amount of coating-compatible silicone to enhance the defoaming performance.

[0030] Preferably, the cellulose thickener includes a product of Shin-Etsu Corporation, with the brand name HS 30000 YP2, which has good flow regulation properties in addition to thickening, suspending, bonding, emulsifying, film-forming, dispersing, water-retaining and protective functions.

[0031] Preferably, the second auxiliary agent includes any one of an antifreeze agent, a film-forming auxiliary agent, and a leveling agent, or a combination of at least two of them.

[0032] Preferably, the second auxiliary agent includes 1-5 parts of antifreeze agent (for example, 1 part, 2 parts, 3 parts, 4 parts, 5 parts, etc.), 2.5-5 parts of film-forming auxiliary agent (for example, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, 5 parts, etc.), and 0.1-0.5 parts of leveling agent (for example, 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, etc.).

[0033] Preferably, the antifreeze agent comprises propylene glycol.

[0034] Preferably, the film-forming aid includes alcohol ester twelve, which is a product of Eastman Chemical Co., Ltd., USA, and its brand is LD506. Alcohol ester twelve has very good hydrolysis stability. When added in small amounts, the latex particles can be more closely and continuously combined during film formation to form a smooth and uniform coating, which greatly improves the scrub resistance and weather resistance of the coating of the present invention. In addition, alcohol ester twelve is easy to add and is a very ideal film-forming aid of the present invention.

[0035] Preferably, the leveling agent includes RM-2020 produced by Dow, which provides a good brushing feel, excellent resistance to roller splashing, water resistance, alkali resistance, scrub resistance and stain resistance, and water resistance; at the same time, it has excellent fluidity and leveling properties, as well as good covering effect, and can provide uniform film thickness and paint film fullness without affecting the gloss characteristics of the coating.

[0036] Preferably, the water-based metal roof rust-removing paint comprises the following components in parts by weight:

[0037]

[0038] As a preferred technical solution of the present invention, the water-based metal roof rust-removing paint comprises the following components in parts by weight:

[0039]

[0040]

[0041] In a second aspect, the present invention provides a method for preparing the water-based metal roof rust-removing coating as described in the first aspect, the preparation method comprising the following steps:

[0042] (1) mixing deionized water and a first auxiliary agent to obtain a first mixture;

[0043] (2) adding an anti-rust pigment filler and a rust-reducing agent to the first mixture under stirring conditions, and dispersing the mixture to obtain a second mixture;

[0044] (3) adding a penetrant, a second auxiliary agent, and an epoxy-modified styrene acrylic emulsion to the second mixture under stirring conditions, and mixing the mixture to obtain the water-based metal roof rust-reducing coating.

[0045] The whole preparation method of the present invention has a simple process, can effectively save costs, has a continuous process, a high degree of mechanization, a large batch processing volume, is suitable for large-scale industrial production, and the prepared product has a good use effect.

[0046] Preferably, the mixing rotation speed in step (1) is 400-600 rpm, for example, 400 rpm, 450 rpm, 500 rpm, 550 rpm, 600 rpm, etc.

[0047] Preferably, the stirring speed in step (2) is 800-1000 rpm, for example, 800 rpm, 850 rpm, 900 rpm, 950 rpm, 1000 rpm, etc.

[0048] Preferably, the dispersion speed in step (2) is 1200-1500 rpm, for example, 1200 rpm, 1250 rpm, 1300 rpm, 1350 rpm, 1400 rpm, 1450 rpm, 1500 rpm, etc.

[0049] Preferably, the dispersion in step (2) is to disperse the mixture to a fineness of ≤80 μm, such as 80 μm, 75 μm, 70 μm, 65 μm, 60 μm, etc.

[0050] Preferably, the stirring speed in step (3) is 400-600 rpm, for example, 400 rpm, 450 rpm, 500 rpm, 550 rpm, 600 rpm, etc.

[0051] Compared with the prior art, the present invention has at least the following beneficial effects:

[0052] (1) The present invention introduces a rust-removing agent and a penetrant into the water-based metal roof rust-removing paint provided, and selects epoxy-modified styrene-acrylic emulsion as the main raw material, so that the rust-removing paint not only has excellent comprehensive performance (such as excellent adhesion, weather resistance, salt spray resistance, etc.), but also has excellent rust-removing and rust-preventing effects.

[0053] (2) The preparation method of the present invention has a simple process, can effectively save costs, has a continuous process, a high degree of mechanization, a large batch processing volume, is suitable for large-scale industrial production, and the prepared product has a good use effect. DETAILED DESCRIPTION

[0054] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0055] Example 1

[0056] In this embodiment, a water-based metal roof rust-removing coating is provided, and the specific preparation process is as follows:

[0057] (1) Preparation: 27.5 parts of deionized water, 0.6 parts of dispersant (Cotai P30), and mildew inhibitor (Hycmax CDT) 0.2 parts, defoaming agent (Hairun Chemical CF1511) 0.3 parts, cellulose thickener (Shin-Etsu HS 30000YP2) 0.3 parts, anti-rust color filler mica iron oxide red 4 parts, anti-rust color filler zinc yellow 4 parts, penetrant (sodium oleyl methyl taurate) 1.4 parts, rust-removing agent (sodium hydrogen sulfate) 3.5 parts, antifreeze agent (propylene glycol) 1.2 parts, film-forming aid (Eastman LD506) 2.7 parts, epoxy modified styrene acrylic emulsion (Senjie Chemical) 54 parts, leveling agent (Dow RM-2020) 0.3 parts;

[0058] (2) adding deionized water, a dispersant, a mildew preventer, a defoamer, and a cellulose thickener in sequence at a rotation speed of 500 rpm, and dispersing until the mixture is uniformly mixed to obtain a first mixture;

[0059] (3) slowly adding the anti-rust pigment filler and the anti-rust agent to the first mixture at a rotation speed of 900 rpm, and dispersing the mixture at a rotation speed of 1400 rpm to a fineness of ≤80 μm to obtain a second mixture;

[0060] (4) At a rotation speed of 500 rpm, a penetrant, an antifreeze agent, a film-forming aid, an epoxy-modified styrene acrylic emulsion, and a leveling agent are sequentially added to the second mixture and mixed evenly to obtain the water-based metal roof rust-removing paint.

[0061] Example 2

[0062] The present embodiment provides a water-based metal roof rust-removing paint, which differs from the embodiment 1 only in that, in parts by weight, the water-based metal roof rust-removing paint includes 5 parts of rust-removing agent, 1.0 parts of penetrant, and 50 parts of epoxy-modified styrene acrylic emulsion, and the amount of deionized water is adjusted so that the total amount of the paint remains unchanged. The other components, amounts, and preparation methods are the same as those in the embodiment 1.

[0063] Example 3

[0064] The present embodiment provides a water-based metal roof rust-removing paint, which differs from the embodiment 1 only in that, in parts by weight, the water-based metal roof rust-removing paint includes 2 parts of rust-removing agent, 1.4 parts of penetrant, and 56 parts of epoxy-modified styrene acrylic emulsion, and the amount of deionized water is adjusted so that the total amount of the paint remains unchanged. The other components, amounts, and preparation methods are the same as those in the embodiment 1.

[0065] Example 4

[0066] This embodiment provides a water-based metal roof rust-removing paint, which differs from Example 1 only in that, by weight, the water-based metal roof rust-removing paint includes 1 part of rust-removing agent, and the amount of deionized water is adjusted so that the total amount of the paint remains unchanged. Other components, amounts and preparation methods are the same as those in Example 1.

[0067] Example 5

[0068] This embodiment provides a water-based metal roof rust-removing paint, which differs from Example 1 only in that, by weight, the water-based metal roof rust-removing paint includes 0.8 parts of a penetrant, and the amount of deionized water is adjusted so that the total amount of the paint remains unchanged. Other components, amounts, and preparation methods are the same as those in Example 1.

[0069] Example 6

[0070] This embodiment provides a water-based metal roof rust-removing paint, which is different from Embodiment 1 only in that the rust-removing agent is replaced with tannic acid in equal parts by weight.

[0071] Example 7

[0072] This embodiment provides a water-based metal roof rust-reducing paint, which differs from Embodiment 1 only in that the penetrant is replaced with an equal weight portion of octylphenol polyoxyethylene ether.

[0073] Comparative Example 1

[0074] This comparative example provides a water-based metal roof rust-removing paint. The difference from Example 1 is that the emulsion in the raw materials uses ordinary styrene acrylic emulsion (Polylide HS-1120), and no penetrant and rust-removing agent are used in the raw materials. The remaining raw materials and methods are the same as those in Example 1 and will not be repeated here.

[0075] Comparative Example 2

[0076] This comparative example provides a water-based metal roof rust-removing paint. The difference from Example 1 is that no penetrant and rust-removing agent are used in the raw materials. The remaining raw materials and methods are the same as those in Example 1 and will not be repeated here.

[0077] Comparative Example 3

[0078] This comparative example provides a water-based metal roof rust-removing paint. The difference from Example 1 is that no rust-removing agent is used in the raw materials. The remaining raw materials and methods are the same as those in Example 1 and will not be repeated here.

[0079] Comparative Example 4

[0080] This comparative example provides a water-based metal roof rust-reducing paint. The difference from Example 1 is that no penetrant is used in the raw materials. The remaining raw materials and methods are the same as those in Example 1 and will not be repeated here.

[0081] Test Case

[0082] The coatings obtained in Examples 1-7 and Comparative Examples 1-4 were tested for adhesion performance according to the cross-hatch method of GB / T9286-1998; the salt spray resistance was tested according to GB / T1771-2007; and the weather resistance was tested according to the artificial weathering aging and artificial radiation exposure (filtered xenon arc radiation) determination method for paints and varnishes of GB / T1865-2009.

[0083] The test method for the thickness of the converted rust is as follows: first prepare a rusty steel plate, and the preparation method is as follows: the original steel plate is subjected to a 7d salt spray test according to GB / T1771-2007 "Determination of neutral salt spray resistance of paints and varnishes", and then subjected to a 7d wet heat test according to GB / T 1740-2007 "Determination of moisture and heat resistance of paint films", and after the test plate is taken out, the floating oil on the surface is cleaned with distilled water, anhydrous ethanol and ethyl acetate in turn, and finally baked at (105±2)°C for 1h to obtain a rusty steel plate; the rust thickness of the rusty steel plate is tested (referred to as H1), and then the coating provided in the embodiment and the comparative example is applied to the surface of the rusty steel plate, and then the rust thickness is tested again (referred to as H2), and the difference between H1 and H2 is the converted rust thickness.

[0084] The performance test results are shown in Table 1.

[0085] Table 1

[0086]

[0087] It can be seen from Table 1 that the water-based metal roof rust-removing coatings provided by Examples 1-5 of the present invention have excellent performance, meet the standards of GB / T9286-1998, GB / T1771-2007, and GB / T1865-2009, and the adhesion can reach level 0, the weather resistance can reach 72h, and the salt spray resistance is 298-385h; and it has excellent rust-removing ability (converted rust thickness: 274-340μm).

[0088] Compared with Example 1, the weather resistance, salt spray resistance, and rust conversion ability of the water-based metal roof rust-converting coatings provided by Comparative Examples 1 and 2 are greatly reduced; the weather resistance, salt spray resistance, and rust conversion ability of the water-based metal roof rust-converting coatings provided by Comparative Examples 3 and 4 are significantly reduced.

[0089] The applicant declares that the present invention uses the above-mentioned embodiments to illustrate the water-based metal roof rust-reducing paint and the preparation method thereof, but the present invention is not limited to the above-mentioned embodiments, that is, it does not mean that the present invention must rely on the above-mentioned embodiments to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A water-based metal roof rust-removing paint, characterized in that: The water-based metal roof rust-removing paint comprises the following components in parts by weight:

2. The water-based metal roof rust-reducing paint according to claim 1, characterized in that: The anti-rust pigment filler includes any one of mica iron oxide red, zinc phosphate, aluminum dihydrogen tripolyphosphate, zinc yellow, zinc oxide, talcum powder, and barium sulfate, or a combination of at least two of them.

3. The water-based metal roof rust-reducing paint according to claim 1 or 2, characterized in that: The rust-removing agent includes sodium bisulfate.

4. The water-based metal roof rust-reducing paint according to any one of claims 1 to 3, characterized in that: Such penetrants include sodium oleoyl methyl taurate.

5. The water-based metal roof rust-reducing paint according to any one of claims 1 to 4, characterized in that: The first auxiliary agent includes any one or a combination of at least two of a dispersant, a mildew preventer, a defoamer, and a cellulose thickener; Preferably, the first auxiliary agent includes 0.1-1.0 part of a dispersant, 0.1-0.5 part of a mildew preventer, 0.1-0.6 part of a defoamer, and 0.2-0.5 part of a cellulose thickener.

6. The water-based metal roof rust-reducing paint according to any one of claims 1 to 5, characterized in that: The second auxiliary agent includes any one of an antifreeze agent, a film-forming auxiliary agent, and a leveling agent, or a combination of at least two thereof; Preferably, the second auxiliary agent includes 1-5 parts of antifreeze agent, 2.5-5 parts of film-forming auxiliary agent, and 0.1-0.5 parts of leveling agent.

7. The water-based metal roof rust-reducing paint according to any one of claims 1 to 6, characterized in that: The water-based metal roof rust-removing paint comprises the following components in parts by weight:

8. The water-based metal roof rust-reducing paint according to any one of claims 1 to 7, characterized in that: The water-based metal roof rust-removing paint comprises the following components in parts by weight:

9. A method for preparing a water-based metal roof rust-reducing coating as claimed in any one of claims 1 to 8, characterized in that: The preparation method comprises the following steps: (1) mixing deionized water and a first auxiliary agent to obtain a first mixture; (2) adding an anti-rust pigment filler and a rust-reducing agent to the first mixture under stirring conditions, and dispersing the mixture to obtain a second mixture; (3) adding a penetrant, a second auxiliary agent, and an epoxy-modified styrene acrylic emulsion to the second mixture under stirring conditions, and mixing the mixture to obtain the water-based metal roof rust-reducing coating.

10. The preparation method according to claim 9, characterized in that: The mixing speed in step (1) is 400-600 rpm; Preferably, the stirring speed in step (2) is 800-1000 rpm; Preferably, the dispersion speed in step (2) is 1200-1500 rpm; Preferably, the dispersion in step (2) is to disperse the mixture to a fineness of ≤80 μm; Preferably, the stirring speed in step (3) is 400-600 rpm.

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