CN112795260B - A kind of water-based rust conversion shielding coating and preparation method thereof - Google Patents

Abstract

The application discloses a water-based rust conversion shielding coating and a preparation method thereof, and relates to the technical field of coatings. The water-based rust conversion shielding paint is mainly prepared from the following paint raw materials in parts by weight: 75-95 parts of dichloroethylene modified acrylic emulsion, 6-14 parts of organic acid aqueous solution, 1-2 parts of film-forming polymer and 0.05-0.15 part of wetting agent; the organic acid aqueous solution contains 25-35 wt% of organic acid, and the balance of water; the organic acid comprises tannic acid. It has the advantage that the constructability is good. The preparation method has the advantage of improving the application property of the product.

Description

A kind of water-based rust conversion shielding coating and preparation method thereof

technical field

The present application relates to the technical field of coatings, in particular to a water-based rust conversion shielding coating and a preparation method thereof.

Background technique

Coating is a substance that is used to coat the surface of the object to be protected or decorated, and can form a continuous film with a certain adhesion on the surface of the object to be coated; the coating is usually based on resin, oil or emulsion, adding pigments, Fillers and auxiliaries, viscous liquids prepared with organic solvents or water. Spraying paint on the surface of metal materials can help protect metal materials and prolong the service life of metal materials. The surface of the metal material is easily corroded, and there is often a certain amount of rust. After the coating is sprayed, the metal substrate with rust on the surface is more likely to be further oxidized, the rust increases, and the volume expands, causing the coating layer to crack, thus affecting the durability of the coating. , causing moisture and oxygen to enter, forming more rust, which in turn affects the aesthetics and affects the service life of the metal and paint layers.

In order to prolong the service life of the paint layer, the commonly used related technology is to polish the metal surface with brushes, wire brushes and other tools to remove rust and then spray the paint, which helps to delay corrosion and prolong the service life of the paint layer.

In view of the above-mentioned related art, the inventor believes that the rust on the metal surface needs to be completely removed to achieve a good anti-corrosion effect. The surface needs to be polished for a long time to meet the requirements, and the construction period is long, which has a certain adverse effect on the workability of the coating.

SUMMARY OF THE INVENTION

In order to improve the construction performance of the coating, the present application provides a water-based rust conversion shielding coating and a preparation method thereof.

In the first aspect, the application provides a water-based rust conversion shielding coating, which adopts the following technical solutions:

A water-based rust conversion shielding coating is mainly prepared from coating raw materials including the following parts by weight: 75-95 parts of vinylidene chloride modified acrylic emulsion, 6-14 parts of organic acid aqueous solution, 1-2 parts of film-forming polymer, moisturizing 0.05-0.15 part of wetting agent; the organic acid aqueous solution contains 25-35% by weight of organic acid, and the rest is water; the organic acid includes tannic acid.

By adopting the above technical solution, the present application adds an organic acid aqueous solution containing tannic acid to the raw material for preparing the water-based rust conversion shielding coating, and the tannic acid molecule contains a pyrogallol group, and the pyrogallol group and the metal surface are closely related. Iron oxide reacts chemically to form stable iron salts of tannin, which act as a shield and help prevent further corrosion of the metal. The application only needs to remove the floating rust and the rusted part of the metal surface, which produces a good shielding protection effect through chemical reaction, and achieves the corrosion inhibition effect through passivation, and improves the corrosion resistance of the product; the application does not need to completely remove the metal The rust on the surface saves time and effort; especially for the special-shaped metal surface and in the working conditions that are inconvenient for grinding or hot work, using the water-based rust conversion shielding coating prepared by the application saves time and effort, and the application improves the construction of the coating product sex. The present application uses dichloroethylene modified acrylic emulsion and wetting agent in the raw materials for preparing water-based rust conversion barrier coatings. The acrylic emulsion modified with dichloroethylene has good compatibility with tannic acid, and the dichloroethylene modified Acrylic emulsion and wetting agent work together to help improve the compatibility between organic acid containing tannic acid and resin emulsion, help organic acid to be uniformly dispersed in coating products, and help to better perform rust transfer It can help to improve the adhesion of the coating on the metal surface, and better improve the salt spray resistance and impact resistance of the coating product.

Preferably, it is mainly made of coating materials including the following parts by weight: 82-88 parts of vinylidene chloride modified acrylic emulsion, 8.5-11.5 parts of organic acid aqueous solution, 1.3-1.7 parts of film-forming polymer, and 0.08-0.12 parts of wetting agent share. More preferably, 85 parts of vinylidene chloride modified acrylic emulsion, 10 parts of organic acid aqueous solution, 1.5 parts of film-forming polymer, and 0.1 part of wetting agent. More preferably, the organic acid mass concentration in the organic acid aqueous solution is 30%.

By adopting the above technical solutions and using a better ratio of raw materials, it will help to better improve the compatibility between the components in the coating, better improve the adhesion of the coating product on the surface of the substrate, and To improve the product's salt spray resistance and impact resistance.

Preferably, the organic acid is composed of tannic acid, oxalic acid, and citric acid in a weight ratio of 1:(0.3-0.36):(0.3-0.36).

By adopting the above technical scheme, oxalic acid and citric acid are used to act together with tannic acid to completely react with rust, so as to improve the rust transfer efficiency and better improve the salt spray resistance and impact resistance of the product.

Preferably, the median particle size of the vinylidene chloride-modified acrylic emulsion is not greater than 150 nm, and the pH is 2-3.

By adopting the above technical solution, the common acrylic emulsion is weakly alkaline, and the vinylidene chloride modified acrylic emulsion used in this application is acidic, and has better compatibility with acidic organic acids; Acrylic emulsion helps the organic acid penetrate better into the surface of the metal substrate, passivate the metal surface, increase the contact area with the metal substrate, improve the adhesion of the coating on the surface of the substrate, and better improve the product The impact resistance is helpful to prolong the service life of the product and is conducive to the promotion of the product in the market.

Preferably, the film-forming polymer is dodecyl alcohol ester.

By adopting the above technical solution, the use of dodecyl alcohol ester film-forming polymer can help the coating to form a film on the surface of the substrate better, help to improve the adhesion of the coating on the surface of the substrate, and better improve the product The impact resistance is helpful to prolong the service life of the product and is conducive to the promotion of the product in the market.

Preferably, the wetting agent is a polyether siloxane copolymer wetting agent.

By adopting the above technical scheme, the use of polyether siloxane copolymer wetting agent helps to improve the compatibility between the coating and the substrate, helps the coating to adhere to the surface of the substrate better, and better Improve the impact resistance of the product and help prolong the service life of the product.

Preferably, the coating material further includes 0.25-0.35 parts by weight of a bactericide.

By adopting the above technical scheme, adding a bactericide to the coating raw material helps to improve the antibacterial performance of the coating product, helps to delay corrosion, and helps to prolong the service life of the product.

Preferably, the coating material further comprises 0.15-0.3 parts by weight of dialdehyde-based polyethylene glycol.

By adopting the above technical scheme, the dialdehyde-based polyethylene glycol is added to the coating material, the compatibility between the dialdehyde-based polyethylene glycol and the tannic acid is good, and the dialdehyde-based polyethylene glycol is modified with dichloroethylene. The compatibility between acrylic emulsions is good, and the addition of dialdehyde-based polyethylene glycol helps to improve the adhesion of the coating on the surface of the substrate and better improve the impact resistance of the product.

In the second aspect, the application provides a preparation method of a water-based rust conversion shielding coating, which adopts the following technical scheme:

A method for preparing a water-based rust conversion shielding coating comprises the following steps: weighing coating raw materials, and stirring at a speed of 700-1000 rpm for 25-35 minutes to prepare the water-based rust conversion shielding coating.

By adopting the above technical scheme and using a faster rotating speed to prepare the coating, it is helpful for the components in the coating to be uniformly dispersed in the coating product, and the salt spray resistance and impact resistance of the product are better improved.

To sum up, the present application includes at least one of the following beneficial technical effects:

1. the application adds the organic acid aqueous solution containing tannic acid in the preparation of water-based rust conversion shielding coating raw materials, and the tannic acid molecule contains a pyrogallol group, and the pyrogallol group and the iron oxide on the metal surface are chemically generated. The reaction generates stable tannic acid iron salt, which has a shielding effect and prevents further corrosion of the metal; the application only needs to remove the floating rust and the rusted part of the metal surface, and produce a good shielding protection effect through chemical reaction. , through passivation to achieve corrosion inhibition effect and improve product corrosion resistance; this application does not need to completely remove rust on the metal surface, saving time and effort, especially for special-shaped metal surfaces and under conditions that are inconvenient for grinding or hot work, improve The workability of the coating product is improved; in this application, the vinylidene chloride modified acrylic emulsion and the wetting agent are used in the preparation of the raw materials of the water-based rust conversion shielding coating, which helps to improve the compatibility between the organic acid containing tannic acid and the resin emulsion. It helps to uniformly disperse the organic acid in the coating product, helps to better play the role of rust transfer, helps to improve the adhesion of the coating on the metal surface, and better improves the salt spray resistance and resistance of the coating product. impact performance;

2. In this application, dialdehyde-based polyethylene glycol is added to the coating raw materials, and the compatibility between the dialdehyde-based polyethylene glycol and tannic acid is good, and the dialdehyde-based polyethylene glycol and vinylidene chloride modified acrylic emulsion The compatibility between them is good, and the addition of dialdehyde-based polyethylene glycol helps to improve the adhesion of the coating on the surface of the substrate and better improve the impact resistance of the product;

3. The water-based rust conversion barrier coating prepared by the present application also has the following advantages: no alkylphenol polyoxyethylene ether (APEO) compounds are used, the VOC content is significantly reduced, environmental protection and energy saving; the substrate does not need to be polished and derusted, and can be directly Use, construction is simple; the coating film structure is regular, the arrangement is tight, the rust transformation is complete, and the efficiency is high; the use of small particle size emulsion penetrates into the metal substrate to passivate the metal surface and increase the contact area with the metal substrate, thereby Improve the adhesion of the coating; the coating after rusting has a good barrier to moisture, if used in conjunction with the topcoat, the anti-corrosion performance of the overall composite coating is significantly improved.

Detailed ways

The inventor found in the research that when spraying the metal surface with the commonly used coating products on the market, the metal surface needs to be polished with tools such as brushes, wire brushes, etc. to completely remove the rust on the metal surface, so that the metal products can maintain good corrosion resistance. . It is time-consuming and laborious to completely remove the rust on the metal surface. It takes a long time to grind to meet the requirements. The construction period is long and the workability is not good. Especially for the special-shaped metal surface, there are corners and other inconvenient grinding parts on the special-shaped metal surface. Incomplete rust removal will also affect the The service life of the product; the paint workability is not good in the environment where it is not convenient for grinding or hot work.

In the present application, an organic acid aqueous solution containing tannic acid is added to the raw material for preparing the water-based rust conversion shielding coating, and the tannic acid molecule contains a pyrogallol group, and the pyrogallol group chemically reacts with the iron oxide on the metal surface, Generates stable iron tannin salts, shielding and preventing further corrosion of metals. The application only needs to remove the floating rust and the rusted part of the metal surface, which produces a good shielding protection effect through chemical reaction, and achieves the corrosion inhibition effect through passivation, and improves the corrosion resistance of the product; the application does not need to completely remove the metal The rust on the surface saves time and effort, especially for special-shaped metal surfaces and in the use conditions that are inconvenient for grinding or hot work, improving the workability of coating products. The application uses dichloroethylene-modified acrylic emulsion and wetting agent in the preparation of raw materials for water-based rust conversion shielding coatings, which helps to improve the compatibility between the organic acid containing tannic acid and the resin emulsion, and helps the organic acid It is evenly dispersed in the coating product, which helps to better play the role of rust transfer, helps to improve the adhesion of the coating on the metal surface, and improves the salt spray resistance and impact resistance of the coating product.

The reaction formula of the chemical reaction of tannin and rust in the coating of the application is as follows:

The composite coating made of the water-based conversion shielding coating of the present application and other surface layers can significantly improve the salt spray resistance effect. The water-based rust conversion shielding coating prepared by the application has good adhesion on various substrates, and has a wide range of applications, which can be applied to chassis, axles, railway bogie frames, railway trains, subway trains, intercity trains, steel structures , building construction, bridge construction, heavy machinery and equipment, metal roofing, steel tanks and containers and other fields.

The raw materials involved in this application are all commercially available, and the models and sources of the raw materials are shown in Table 1.

Table 1 Specifications, models and sources of raw materials

Example

Embodiment 1: the preparation method of water-based rust conversion shielding coating, comprises the steps:

Take tannic acid and water to prepare a tannic acid aqueous solution with a mass concentration of 30%. Take 8.5kg of vinylidene chloride modified acrylic emulsion, add 150g of dodecyl alcohol ester film-forming polymer, 10g of wetting agent and 1kg of tannic acid aqueous solution in turn, and stir at 800 rpm for 30min to obtain water-based rust conversion Barrier paint.

Example 2

The difference between Example 2 and Example 1 is that in Example 2, an organic acid aqueous solution with a mass concentration of 30% is used instead of the tannic acid aqueous solution. The weight ratio of 0.1 is the same as that of Example 1.

Example 3

The difference between Example 3 and Example 2 is that the ratio of each component in the organic acid of Example 3 is different. In Example 3, the organic acid is composed of tannic acid, oxalic acid, and citric acid in a weight ratio of 3:1:1 The composition is the same as in Example 2.

Example 4

The difference between Example 4 and Example 3 is that 30 g of bactericide is added to the coating material of Example 4, and the others are consistent with Example 3.

Example 5

The difference between Example 5 and Example 4 is that 20 g of dialdehyde-based polyethylene glycol is added to the coating material of Example 5, and the others are consistent with Example 4.

Examples 6-14

The difference between Example 6-14 and Example 5 is that the addition amount of each raw material in Example 6-14 is different, and the others are consistent with Example 5. The addition amount of each raw material in Example 6-10 is shown in Table 4. Examples The addition amount of each raw material of 11-14 is shown in Table 5.

The addition amount of each raw material of table 4 embodiment 6-10

Table 5 The addition amount of each raw material in Examples 11-14

Examples 15-19

The difference between Examples 15-19 and Example 5 is that the process parameters of each step in Examples 15-19 are different, and the others are consistent with Example 5. The process parameters of each step in Examples 15-19 are shown in Table 6.

Table 6 Parameters in each step of Example 15-19

Comparative ratio

Comparative Example 1

The difference between Comparative Example 1 and Example 1 is that Comparative Example 1 does not add an aqueous tannic acid solution, and the others are consistent with Example 1.

Comparative Example 2

The difference between Comparative Example 2 and Example 1 is that in Comparative Example 2, the same mass of citric acid aqueous solution of the same concentration was used instead of the tannic acid aqueous solution, and the others were consistent with Example 1.

Comparative Example 3

The difference between Comparative Example 3 and Example 1 is that Comparative Example 3 uses the same quality of ordinary acrylic emulsion (provided by Shandong Haoshun Chemical Co., Ltd., model HS109, pH is 8.6, median particle size 124nm) instead of vinyl chloride modified acrylic acid Emulsion, others are the same as in Example 1.

Comparative Example 4

The difference between Comparative Example 4 and Example 1 is that no wetting agent is added in Comparative Example 4, and the others are consistent with Example 1.

Performance testing

1. Salt spray resistance: Refer to GB/T1771-2007 "Determination of Neutral Salt Spray Resistance of Paints and Varnishes" to measure salt spray resistance. The test period is 20d. Observe and record the test with reference to ISO4628-3:2003. After the rust grade, the experimental results are shown in Table 7.

2. Impact resistance: Refer to GB/T1732-1993 "Determination of Impact Resistance of Paint Films" to measure impact resistance, observe and record the height of the weight with cracks, wrinkles or peeling with a 4x magnifying glass. The experimental results are as follows Table 7.

3. Determination of VOC content: Refer to GB/T23986-2009 "Determination of Volatile Organic Compounds (VOC) Content in Paints and Varnishes by Gas Chromatography" to determine the volatile organic compound (VOC) content. The experimental results are shown in Table 7.

4. Durable antibacterial rate: Refer to GB/T21866-2008 "Antibacterial coating (paint film) antibacterial property determination method and antibacterial effect", carry out an antibacterial durability performance test, and test the durable antibacterial rate. The experimental results are shown in Table 7.

Table 7 Comparison table of performance test results of different coating products

Compared with Example 1, Comparative Example 1 does not add tannic acid aqueous solution, and the prepared coating product has poor anti-corrosion performance and poor salt spray resistance, which is not conducive to product market promotion. In Comparative Example 2, the tannic acid aqueous solution was not added, but the citric acid aqueous solution was added, and the salt spray resistance of the prepared coating product did not change significantly. Comparative Example 3 Using ordinary acrylic emulsion, not using vinylidene chloride modified acrylic emulsion, and adding tannic acid aqueous solution, because ordinary acrylic emulsion is alkaline and has poor compatibility with acidic tannic acid, the prepared coating product It has poor salt spray resistance, poor impact resistance, high VOC content, and poor antibacterial effect, which is not conducive to product market promotion. In Comparative Example 4, no wetting agent was added, and the vinylidene chloride modified acrylic emulsion was used. The salt spray resistance of the prepared coating product was slightly improved, but the salt spray resistance was still poor, the impact resistance was poor, and the VOC content was low. , poor antibacterial effect, is not conducive to product marketing.

By analyzing the experimental results of Comparative Examples 1-2, it can be seen that without adding tannic acid or using citric acid instead of tannic acid, the prepared coating product has poor salt spray resistance. By analyzing the experimental results of Comparative Examples 3-4, it can be seen that only using dichloroethylene modified acrylic emulsion without adding wetting agent can improve the salt spray resistance to a certain extent, and has little effect on the impact resistance; Wetting agent, without the use of vinylidene chloride modified acrylic emulsion, has no obvious effect on the salt spray resistance and impact resistance of the product. Comparing the experimental results of Example 1 and Comparative Examples 1-4, it can be seen that in the process of preparing the coating, adding the organic acid aqueous solution containing tannic acid, the vinylidene chloride modified acrylic emulsion and the wetting agent are used together. The synergistic effect of these substances improves the compatibility between the components in the coating, helps the tannic acid to be uniformly dispersed in the coating product, improves the corrosion resistance of the product, and significantly improves the salt spray resistance of the coating product; At the same time, the adhesion performance of the coating on the substrate is improved, the impact resistance of the coating product is improved, the service life of the product is prolonged, and the market promotion of the product is facilitated.

Comparing the experimental results of Example 1 and Example 2, Example 2 uses an organic acid composed of tannic acid, oxalic acid and citric acid to replace a single tannic acid, but because no suitable tannic acid, oxalic acid and citric acid are used If the dosage of oxalic acid is too much and the dosage of tannin is too small, the salt spray resistance of the prepared product is not significantly improved. Contrasting the experimental results of Example 2 and Example 3, Example 3 selects suitable tannic acid, oxalic acid and citric acid ratios, because there is a certain synergy between tannic acid, oxalic acid and citric acid, the rusting efficiency is higher. High, which helps to improve the corrosion resistance of the product, and significantly improves the salt spray resistance of the coating product.

Comparing the experimental results of Example 3 and Example 4, a certain amount of bactericide was added in Example 4, which helped to improve the antibacterial performance of the coating product, and the antibacterial performance of the product was significantly improved. Comparing the experimental results of Example 4 and Example 5, the addition of a certain amount of dialdehyde-based polyethylene glycol in Example 5 helps to better improve the compatibility between the organic acid and the emulsion, and helps Improve the adhesion of the coating on the substrate, and the impact resistance of the coating product is significantly improved, which helps to prolong the service life of the product and is conducive to product market promotion.

Compared with Example 5, the addition amount of each raw material in Examples 6-14 is different, wherein the amount of antibacterial agent in Example 8 and Example 13 is less, and the antibacterial effect of the coating product is slightly reduced; In Example 10, the amount of antibacterial agent was larger, and the antibacterial effect of the coating product was better; in Example 7, Example 8 and Example 10, the amount of organic acid was relatively small, the rust-turning effect was slightly reduced, and the salt spray resistance was slightly reduced. . In Examples 11-14, the appropriate ratio of raw materials is used, and the obtained coating products have low VOC content, obvious antibacterial effect, excellent salt spray resistance and impact resistance, which help to prolong the service life of the product and are beneficial to the product. Marketing.

Compared with Example 5, the process parameters of each step in Examples 15-19 are different; the stirring speed of Example 15 is lower, and the salt spray resistance and impact resistance of the obtained coating product are reduced; Example 16-19 By selecting appropriate process parameters, the obtained coating product has low VOC content, obvious antibacterial effect, excellent salt spray resistance and impact resistance, which helps to prolong the service life of the product and is conducive to product market promotion.

The embodiments of this specific embodiment are all preferred embodiments of the present application, and do not limit the protection scope of the present application accordingly. Therefore: all equivalent changes made according to the structure, shape and principle of the present application should be covered in within the scope of protection of this application.

Claims (5)

1. The water-based rust conversion shielding coating is characterized by being mainly prepared from the following coating raw materials in parts by weight: 75-95 parts of dichloroethylene modified acrylic emulsion, 6-14 parts of organic acid aqueous solution, 1-2 parts of film-forming polymer, 0.05-0.15 part of wetting agent and 0.15-0.3 part of dialdehyde polyethylene glycol; the organic acid aqueous solution contains 25-35 wt% of organic acid, and the balance of water; the organic acid is prepared from tannic acid, oxalic acid and citric acid according to the proportion of 1: (0.3-0.36): (0.3-0.36) by weight; the median particle size of the dichloroethylene modified acrylic emulsion is not more than 150nm, and the pH value is 2-3; the wetting agent is a polyether siloxane copolymer wetting agent.

2. The aqueous rust conversion barrier coating of claim 1, which is mainly prepared from the following coating raw materials in parts by weight: 82-88 parts of dichloroethylene modified acrylic emulsion, 8.5-11.5 parts of organic acid aqueous solution, 1.3-1.7 parts of film-forming polymer and 0.08-0.12 part of wetting agent.

3. The aqueous rust conversion barrier coating of claim 1, characterized in that: the film-forming polymer is dodecyl alcohol ester.

4. The aqueous rust conversion barrier coating of claim 1, characterized in that: the coating raw material also comprises 0.25-0.35 weight part of bactericide.

5. A method of preparing the aqueous rust conversion barrier coating of any one of claims 1-4, characterized by comprising the steps of: weighing the raw materials of the coating, and stirring at the rotation speed of 700-1000 r/min for 25-35min to prepare the water-based rust conversion shielding coating.