CN112795260B

CN112795260B - Water-based rust conversion shielding coating and preparation method thereof

Info

Publication number: CN112795260B
Application number: CN202110064042.1A
Authority: CN
Inventors: 季华兴
Original assignee: Chengdu Huaxing Bangde Building Decoration Materials Co ltd
Current assignee: Chengdu Huaxing Bangde Building Decoration Materials Co ltd
Priority date: 2021-01-18
Filing date: 2021-01-18
Publication date: 2022-05-27
Anticipated expiration: 2041-01-18
Also published as: CN112795260A

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

Water-based rust conversion shielding coating and preparation method thereof

Technical Field

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

Background

The coating is a substance which is used for coating the surface of a protected or decorated object and can form a continuous film with certain adhesion on the surface of the coated object; the paint is a viscous liquid prepared by using resin, oil or emulsion as a main body, adding pigment, filler and auxiliary agent and using organic solvent or water. The paint sprayed on the surface of the metal material is beneficial to protecting the metal material and prolonging the service life of the metal material. The surface of a metal material is easy to corrode and often has a certain amount of rust, after the coating is sprayed, a metal substrate with the rust on the surface is further easily oxidized, the rust is increased, the volume is expanded, and the coating layer is cracked, so that the durability of the coating is influenced, moisture and oxygen enter, more rust is formed, the attractiveness is further influenced, and the service life of the metal and the coating layer is influenced.

In order to prolong the service life of the coating layer, the currently common related technology is to polish the metal surface by using tools such as a brush, a steel wire brush and the like to remove rust and then spray the coating, which is beneficial to delaying corrosion and prolonging the service life of the coating layer.

In view of the above-mentioned related technologies, the inventor believes that a good corrosion prevention effect can be achieved by completely removing rust on the metal surface, and the rust on the metal surface cannot be completely removed by polishing and derusting with tools such as a brush, and particularly for a special-shaped metal surface, long-time polishing is required to achieve the requirement, the construction period is long, and certain adverse effects are brought to the application property of the coating.

Disclosure of Invention

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

In a first aspect, the present application provides an aqueous rust conversion barrier coating, which adopts the following technical scheme:

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.

Through adopting above-mentioned technical scheme, this application adds the organic acid aqueous solution that contains tannic acid in preparing waterborne rust conversion shielding coating raw materials, contains pyrogallol group in the tannic acid molecule, and the chemical reaction takes place for pyrogallol group and the iron oxide on metal surface, generates stable tannic acid molysite, takes place shielding action, helps preventing that the metal is corroded by further. According to the method, only the rust and the rusty and crusted part on the metal surface are removed, a good shielding and protecting effect is generated through a chemical reaction, a corrosion inhibition effect is achieved through passivation, and the corrosion resistance of the product is improved; the rust on the metal surface does not need to be thoroughly removed, so that time and labor are saved; especially to special-shaped metal surface and under inconvenient use operating mode of polishing or getting angry, use the waterborne rust conversion shielding coating of this application preparation, labour saving and time saving, this application has improved the constructability of coating product. According to the method, the dichloroethylene modified acrylic emulsion and the wetting agent are used in the raw materials for preparing the water-based rust conversion shielding coating, the acrylic emulsion modified by dichloroethylene has good compatibility with tannic acid, the dichloroethylene modified acrylic emulsion and the wetting agent act together to help to improve the compatibility between organic acid containing tannic acid and resin emulsion, the organic acid is uniformly dispersed in a coating product, the rust conversion effect is better exerted, the adhesive force of the coating on the metal surface is improved, and the salt spray resistance and the impact resistance of the coating product are better improved.

Preferably, the paint is mainly prepared from the following 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. Preferably 85 parts of dichloroethylene modified acrylic acid 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 mass concentration of the organic acid in the aqueous solution of the organic acid is 30%.

By adopting the technical scheme, the better raw material feeding proportion is used, which is beneficial to better improving the compatibility among all components in the coating, better improving the adhesive force of the coating product on the surface of the base material and better improving the salt spray resistance and the impact resistance of the product.

Preferably, the organic acid is prepared from tannic acid, oxalic acid and citric acid according to the weight ratio of 1: (0.3-0.36): (0.3-0.36) in weight ratio.

By adopting the technical scheme, the oxalic acid and the citric acid are used to react with the iron rust completely under the combined action of the tannic acid, so that the rust conversion efficiency is improved, and the salt spray resistance and the impact resistance of the product are improved better.

Preferably, the median particle size of the dichloroethylene modified acrylic emulsion is not more than 150nm, and the pH value is 2-3.

By adopting the technical scheme, the common acrylic emulsion is alkalescent, and the dichloroethylene modified acrylic emulsion used in the application is acidic and has better compatibility with acidic organic acids; the dichloroethylene modified acrylic emulsion with small particle size is beneficial to better permeating organic acid to the surface of a metal base material, passivating the metal surface, increasing the contact area with the metal base material, improving the adhesive force of a coating on the surface of the base material, better improving the shock resistance of a product, prolonging the service life of the product and being beneficial to market popularization of the product.

Preferably, the film-forming polymer is a dodecanol ester.

By adopting the technical scheme, the dodecanol ester film-forming polymer is used, so that the coating can be better formed on the surface of the base material, the adhesion of the coating on the surface of the base material can be improved, the shock resistance of the product can be better improved, the service life of the product can be prolonged, and the market popularization of the product can be facilitated.

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

By adopting the technical scheme, the polyether siloxane copolymer wetting agent is used, so that the compatibility between the coating and the substrate is improved, the coating is favorably adhered to the surface of the substrate, the impact resistance of the product is favorably improved, and the service life of the product is favorably prolonged.

Preferably, the coating raw material also comprises 0.25-0.35 weight part of bactericide.

By adopting the technical scheme, the bactericide is added into the coating raw material, so that the antibacterial performance of the coating product is improved, the corrosion is delayed, and the service life of the product is prolonged.

Preferably, the coating raw material also comprises 0.15-0.3 part by weight of dialdehyde polyethylene glycol.

By adopting the technical scheme, the dialdehyde polyethylene glycol is added into the raw materials of the coating, the compatibility between the dialdehyde polyethylene glycol and the tannin is good, the compatibility between the dialdehyde polyethylene glycol and the dichloroethylene modified acrylic emulsion is good, and the adding of the dialdehyde polyethylene glycol is beneficial to improving the adhesive force of the coating on the surface of the base material and better improving the shock resistance of the product.

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

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

By adopting the technical scheme, the coating is prepared at a faster rotating speed, so that the components in the coating are uniformly dispersed in a coating product, and the salt spray resistance and the impact resistance of the product are better improved.

In summary, the present application includes at least one of the following beneficial technical effects:

1. according to the method, an organic acid aqueous solution containing tannic acid is added into a raw material for preparing the aqueous rust conversion shielding paint, molecules of the tannic acid contain pyrogallol groups, and the pyrogallol groups and iron oxide on the surface of metal are subjected to chemical reaction to generate stable iron salt of the tannic acid, so that a shielding effect is generated, and further corrosion of the metal is prevented; according to the method, only the rust and the rusty and crusted part on the metal surface are removed, a good shielding and protecting effect is generated through a chemical reaction, a corrosion inhibition effect is achieved through passivation, and the corrosion resistance of the product is improved; the rust on the metal surface does not need to be thoroughly removed, time and labor are saved, and particularly, the application method improves the application property of the coating product on the special-shaped metal surface and under the use working condition that polishing or firing is inconvenient; the dichloroethylene modified acrylic acid emulsion and the wetting agent are used in the raw materials for preparing the water-based rust conversion shielding coating, so that the compatibility between organic acid containing tannic acid and resin emulsion is improved, the organic acid is uniformly dispersed in a coating product, the rust conversion effect is better exerted, the adhesive force of the coating on the metal surface is improved, and the salt spray resistance and the impact resistance of the coating product are better improved;

2. according to the application, the dialdehyde polyethylene glycol is added into the raw materials of the coating, the compatibility between the dialdehyde polyethylene glycol and tannic acid is good, the compatibility between the dialdehyde polyethylene glycol and dichloroethylene modified acrylic emulsion is good, and the adding of the dialdehyde polyethylene glycol is beneficial to improving the adhesive force of the coating on the surface of a base material and better improving the shock resistance of a product;

3. the aqueous rust conversion shielding coating prepared by the method also has the following advantages: alkylphenol Polyoxyethylene Ether (APEO) -containing compounds are not used, so that the VOC content is obviously reduced, and the environment is protected and the energy is saved; the base material does not need polishing and rust removal treatment, can be directly used and is simple to construct; the coating structure is regular and compact, the corrosion conversion is thorough, and the efficiency is high; the emulsion with small particle size is used to permeate into the metal base material to passivate the metal surface of the metal base material, so that the contact area of the metal base material and the metal base material is increased, and the adhesive force of the coating is improved; the rusted coating has good barrier property to moisture, and if the rusted coating is matched with finish paint, the corrosion resistance of the integral composite coating is obviously improved.

Detailed Description

The inventor finds in research that when the metal surface is sprayed by using the coating products commonly used in the market, the metal surface needs to be polished by using tools such as a hairbrush, a wire brush and the like to completely remove rust on the metal surface, so that the metal product can keep good corrosion resistance. The rust on the metal surface is thoroughly removed, the time and the labor are wasted, the requirement can be met only by long-time polishing, the construction period is long, and the construction performance is poor; particularly, for the special-shaped metal surface, corners and other parts which are inconvenient to polish exist on the special-shaped metal surface, the service life of the product can be influenced due to incomplete rust removal; the coating has poor application property in the environment of inconvenient polishing or fire.

This application adds the organic acid aqueous solution that contains tannic acid in preparing waterborne rust conversion shielding coating raw materials, contains pyrogallol group in the tannic acid molecule, and the chemical reaction takes place for pyrogallol group and the iron oxide on metal surface, generates stable tannic acid molysite, takes place shielding effect, prevents the further corrosion of metal. According to the method, only the rust and the rusty and crusted part on the metal surface are removed, a good shielding and protecting effect is generated through a chemical reaction, a corrosion inhibition effect is achieved through passivation, and the corrosion resistance of the product is improved; this application need not thoroughly to clear away the iron rust on metal surface, and labour saving and time saving has improved the constructability of coating product especially to special-shaped metal surface and under inconvenient polishing or the use operating mode that moves a fire. The dichloroethylene modified acrylic emulsion and the wetting agent are used in the preparation of the water-based rust conversion shielding coating raw material, so that the compatibility between organic acid containing tannic acid and resin emulsion is improved, the organic acid is uniformly dispersed in a coating product, the rust conversion effect is better played, the adhesive force of the coating on the metal surface is improved, and the salt spray resistance and the impact resistance of the coating product are improved.

The reaction formula of the rust conversion chemical reaction between the tannic acid and the rust in the coating is as follows:

the composite coating that other surface courses of this application waterborne conversion barrier coating cooperation were made, salt spray resistant effect promotes and is showing. The water-based rust conversion shielding coating prepared by the method has good adhesive force on various base materials, is wide in application range, and can be applied to the fields of chassis, axles, railway bogie frames, railway trains, subway trains, intercity trains, steel structures, building construction, bridge construction, heavy machinery equipment, metal roofs, steel tanks, containers and the like.

The raw materials referred to in the present application are all commercially available, and the type and source of the raw materials are shown in table 1.

TABLE 1 Specification, type and origin of the raw materials

Examples

Example 1: the preparation method of the water-based rust conversion shielding paint comprises the following steps:

tannic acid and water are prepared into tannic acid water solution with the mass concentration of 30%. And taking 8.5kg of dichloroethylene modified acrylic emulsion, sequentially adding 150g of dodecyl alcohol ester film-forming polymer, 10g of wetting agent and 1kg of tannic acid aqueous solution, and stirring at the rotating speed of 800 revolutions per minute for 30min to prepare the water-based rust conversion shielding paint.

Example 2

Example 2 differs from example 1 in that example 2 uses an aqueous solution of an organic acid having a mass concentration of 30% instead of an aqueous solution of tannic acid, and in example 2 the organic acid is prepared from tannic acid, oxalic acid, and citric acid in a ratio of 1: 0.8: 0.1, the rest being in accordance with example 1.

Example 3

Example 3 differs from example 2 in that the proportions of the components in the organic acid of example 3 are different, and the organic acid of example 3 is prepared from tannic acid, oxalic acid and citric acid in the ratio of 3: 1: 1, the rest of the composition was the same as in example 2.

Example 4

Example 4 differs from example 3 in that 30g of the biocide was added to the coating stock of example 4, all other things remaining the same as in example 3.

Example 5

Example 5 differs from example 4 in that 20g of dialdehyde polyethylene glycol was added to the coating material of example 5, all the other things remaining the same as example 4.

Examples 6 to 14

The difference between examples 6 to 14 and example 5 is that the amounts of the respective raw materials added in examples 6 to 14 are different and the amounts of the respective raw materials added in examples 6 to 10 are shown in Table 4, and the amounts of the respective raw materials added in examples 11 to 14 are shown in Table 5.

TABLE 4 examples 6-10 amounts of raw materials added

TABLE 5 addition amounts of raw materials of examples 11 to 14

Examples 15 to 19

Examples 15-19 differ from example 5 in that the process parameters for each step of examples 15-19 were different and were otherwise identical to those of example 5, and the process parameters for each step of examples 15-19 are shown in Table 6.

TABLE 6 parameters in the various steps of examples 15-19

Comparative example

Comparative example 1

Comparative example 1 differs from example 1 in that comparative example 1 does not include the addition of aqueous tannic acid, and otherwise remains the same as example 1.

Comparative example 2

Comparative example 2 differs from example 1 in that comparative example 2 replaces the aqueous tannic acid solution with an equal mass of an aqueous citric acid solution of the same concentration, all otherwise in accordance with example 1.

Comparative example 3

Comparative example 3 is different from example 1 in that comparative example 3 uses an equal mass of a common acrylic emulsion (model HS109, pH 8.6, median particle diameter 124nm, available from Shandonghao Shunfiki Co., Ltd.) in place of the ethylene dichloride-modified acrylic emulsion, and otherwise remains the same as example 1.

Comparative example 4

Comparative example 4 differs from example 1 in that comparative example 4 does not have a wetting agent and otherwise remains the same as example 1.

Performance detection

1. Salt spray resistance: the salt spray resistance is measured with reference to GB/T1771-2007 determination of neutral salt spray resistance of colored paint and varnish, the test period is 20d, the rust grade after the test is observed and recorded with reference to ISO4628-3:2003, and the test results are shown in Table 7.

2. Impact resistance: the impact resistance was measured with reference to GB/T1732-1993 "determination of impact resistance of paint film", and the height of a weight having cracks, wrinkles or flaking was observed with a 4-fold magnifying glass and recorded, and the results of the test are shown in Table 7.

3. And (3) VOC content determination: the content of Volatile Organic Compounds (VOC) was determined by reference to GB/T23986-2009 gas chromatography for determination of Volatile Organic Compound (VOC) content of paints and varnishes, and the experimental results are shown in table 7.

4. Durable antibacterial rate: an antibacterial durability test is carried out according to GB/T21866-2008 'antibacterial property determination method and antibacterial effect of antibacterial coating (paint film)', and the test results are shown in Table 7.

TABLE 7 comparison table of performance test results of different coatings

Compared with example 1, the paint product prepared in comparative example 1 has poor corrosion resistance and salt spray resistance without adding tannic acid aqueous solution, and is not beneficial to product market popularization. In comparative example 2, the aqueous solution of tannic acid was not added, and the aqueous solution of citric acid was added, so that the salt spray resistance of the obtained coating product was not significantly changed. The paint is prepared by using common acrylic emulsion instead of ethylene dichloride modified acrylic emulsion and adding tannic acid aqueous solution in the comparative example 3, and the common acrylic emulsion is alkaline and has poor compatibility with acidic tannic acid, so that the prepared paint product has poor salt spray resistance, poor impact resistance, higher VOC content and poor antibacterial effect, and is not beneficial to product market popularization. Comparative example 4 no wetting agent was added, and the dichloroethylene modified acrylic emulsion was used, and 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, the VOC content was lower, the antibacterial effect was poor, and the product market promotion was not facilitated.

Analysis of the results of the experiments of comparative examples 1-2 shows that the salt spray resistance of the coating products obtained without tannic acid or with citric acid instead of tannic acid is poor. Analyzing the experimental results of the comparative examples 3 to 4, it can be seen that only the dichloroethylene modified acrylic emulsion is used, and no wetting agent is added, so that the salt spray resistance is improved to a certain extent, and the impact resistance is not greatly influenced; and the wetting agent is added, and the dichloroethylene modified acrylic emulsion is not used, so that the salt spray resistance and the impact resistance of the product are not obviously influenced. Comparing the experimental results of the example 1 and the comparative examples 1 to 4, it can be seen that, in the process of preparing the coating, the organic acid aqueous solution containing tannic acid is added, the dichloroethylene modified acrylic acid emulsion and the wetting agent are used together, and the synergistic effect of the substances improves the compatibility among the components in the coating, is beneficial to the uniform dispersion of tannic acid in the coating product, improves the corrosion resistance of the product, and obviously improves the salt spray resistance of the coating product; meanwhile, the adhesive property 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 popularization of the product is facilitated.

Comparing the experimental results of example 1 and example 2, example 2 uses an organic acid consisting of tannic acid, oxalic acid and citric acid instead of tannic acid alone, but since proper proportioning of tannic acid, oxalic acid and citric acid is not used, the amount of oxalic acid is too large, the amount of tannic acid is too small, and the salt spray resistance of the prepared product is not improved significantly. The experimental results of comparative example 2 and example 3, example 3 chooses suitable tannic acid, oxalic acid and citric acid ratio for use, because have certain synergism between tannic acid, oxalic acid and the citric acid, changes rust efficiency higher, helps improving product corrosion resisting property, has obviously improved the salt spray resistance performance of coating product.

Comparing the experimental results of example 3 and example 4, the addition of a certain amount of bactericide in example 4 is helpful to improve the antibacterial performance of the paint product, and the antibacterial performance of the product is obviously improved. Comparing the experimental results of example 4 and example 5, example 5 adds a certain amount of dialdehyde polyethylene glycol, which is helpful to better improve the compatibility between the organic acid and the emulsion, and is helpful to improve the adhesion of the coating on the substrate, the impact resistance of the coating product is obviously improved, the service life of the product is prolonged, and the product market popularization is facilitated.

Compared with example 5, the addition amount of each raw material in examples 6 to 14 is different, wherein the antibacterial agent is used in a small amount in example 8 and example 13, and the antibacterial effect of the coating product is slightly reduced; the antibacterial agent dosage in the embodiment 7 and the embodiment 10 is larger, and the antibacterial effect of the coating product is better; in examples 7, 8 and 10, the amount of the organic acid used was relatively small, the rust conversion effect was slightly lowered, and the salt spray resistance was slightly lowered. In examples 11 to 14, the coating products prepared by using the appropriate raw material feeding ratio have low VOC content, obvious antibacterial effect, excellent salt spray resistance and impact resistance, and are beneficial to prolonging the service life of the products and the market popularization of the products.

Compared with example 5, the process parameters of the steps of examples 15 to 19 are different; in the embodiment 15, the stirring speed is low, and the salt spray resistance and the impact resistance of the prepared coating product are reduced; the examples 16-19 select proper process parameters, and the prepared coating product has low VOC content, obvious antibacterial effect, excellent salt spray resistance and impact resistance, is beneficial to prolonging the service life of the product and is beneficial to market popularization of the product.

The embodiments of the present invention are preferred embodiments of the present application, and the scope of protection of the present application is not limited by the embodiments, so: all equivalent changes made according to the structure, shape and principle of the present application shall be covered by the protection scope of the present application.

Claims

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.