Non-flammable zinc paste for zinc dust anticorrosive paint and method for preparing the same

Abstract

The application provides a non-flammable zinc paste for zinc powder anticorrosive paint and a preparation method thereof, and the preparation method comprises the following steps: step S1, preparing surface passivation treated flaky zinc powder; and step S2, putting the flaky zinc powder and a wetting agent into a kneader, and mixing and kneading under vacuum to obtain a paste-like zinc powder material; the wetting agent is at least one of dipropylene glycol butyl ether, dipropylene glyyl, and an epoxy resin additive; and the mass percentage of the flaky zinc powder is 67-82%. The zinc paste prepared by the technical scheme of the application is non-flammable, reduces the harm of fine zinc powder dust to human body and the risk coefficient of flammability and explosiveness in the process of use, storage and transportation, and can be universally applied to oil-based epoxy zinc powder paint, water-based epoxy zinc powder paint and Dacromet and other coatings.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of anticorrosive paint, in particular to a non-flammable zinc paste for zinc powder anticorrosive paint and a preparation method thereof. BACKGROUND

[0002] Zinc powder is commonly used in anticorrosive paint and has excellent corrosion resistance. Zinc powder will overflow from the gaps in the equipment during the mixing, transportation, screening, packaging, and unloading of the powder material and adhere to the surface of the equipment and walls, fall to the ground, or be suspended in the air. According to the data, the self-ignition point of spherical zinc powder with a particle size of 47 μm is about 460℃, and the explosion limit is about 500 g / m 3 If the fineness is improved, the activity is stronger, and the ignition point and explosion limit are lower. Once the conditions for explosion are met, dust explosion may occur, and there is a risk of secondary explosion. Zinc paste can effectively reduce the flying of fine powder, but the semi-finished zinc paste of zinc powder paint still contains a large amount of flammable organic solvent, which belongs to flammable liquid, and still has a high risk of flammability and explosiveness.

[0003] For the research and application of metal powder paste, according to the data, the research and application of zinc and aluminum paste are more common. The research on aluminum powder paste is mainly for aluminum paste for batteries, paint or semi-finished paint containing aluminum powder with special surface effect or performance; the research and application of zinc powder paste are commonly used for zinc paste for batteries; and the zinc paste prepared by the wet grinding process generally uses solvents such as petroleum spirits, which cannot be generally used in various zinc powder coatings.

[0004] The preparation of non-flammable zinc paste material is not simply similar to the raw materials of semi-finished zinc powder paint. Most of the semi-finished zinc powder materials are made to order for specific customers and are difficult to be universally used in zinc powder paint; and the zinc powder paint usually contains a large amount of flammable solvent, so the semi-finished zinc powder paint raw material cannot reduce the risk of flammability and explosiveness during transportation. How to prepare fine zinc powder into a paste material that is not easy to burn, which can be universally used in water-based zinc powder paint and oil-based epoxy zinc powder paint, can effectively reduce the risk of burning and explosion during transportation, storage, and use, and has a positive significance for the development of the industry. SUMMARY

[0005] In view of the above technical problems, the present application discloses a non-flammable zinc paste for zinc powder anticorrosive paint and a preparation method thereof, which solves the burning and explosion risk of zinc powder material during transportation, storage, and use.

[0006] To this end, the technical scheme adopted by the present application is as follows:

[0007] A preparation method of a non-flammable zinc paste for zinc powder anticorrosive paint, comprising the following steps:

[0008] Step S1, preparing flaky zinc powder for surface passivation treatment;

[0009] Step S2, putting the flaky zinc powder and wetting agent into a kneader, kneading and mixing under vacuum condition to obtain paste-like zinc powder material; the wetting agent is at least one of dipropylene glycol butyl ether, dipropylene glycol, and epoxy resin additive. The mass percentage of the flaky zinc powder is 67-82%.

[0010] The high-flash-point non-flammable wetting agent used in this technical solution is a high-flash-point (flash point > 95℃) wetting agent that is preferably excellent in compatibility with zinc powder paint. The wetting agent is a water-soluble solvent or a preferred high-flash-point resin. The zinc powder material obtained by using this technical solution is a non-flammable solid material after burning test, and can be generally applied to water-based zinc powder paint, water-based Dacromet coating, and oil-based zinc powder paint with a metal zinc content of ≤60% in the coating.

[0011] As a further improvement of the present application, when the wetting agent is dipropylene glycol butyl ether, the mass percentage of the flaky zinc powder in the paste-like zinc powder material is not more than 82%;

[0012] When the wetting agent is dipropylene glycol, the mass percentage of the flaky zinc powder in the paste-like zinc powder material is not more than 75%;

[0013] When the wetting agent is an epoxy resin additive, the composition of the epoxy resin additive is E-20 epoxy resin or a mixture of E-20 epoxy resin and a diluent, and further, the diluent is at least one of xylene and n-butanol. Further, the mass percentage of the flaky zinc powder in the paste-like zinc powder material is not more than 82%, and the mass percentage of the E-20 epoxy resin is not less than 15%.

[0014] As a further improvement of the present application, when the wetting agent is dipropylene glycol butyl ether, the mass percentage of the flaky zinc powder in the paste-like zinc powder material is 67-82%;

[0015] When the wetting agent is dipropylene glycol, the mass percentage of the flaky zinc powder in the paste-like zinc powder material is 65-75%;

[0016] When the wetting agent is an epoxy resin additive, the mass percentage of the flaky zinc powder in the paste-like zinc powder material is 67-80%, and the mass percentage of the E-20 epoxy resin is 15-24%.

[0017] As a further improvement of the present application, in step S1, the flaky zinc powder for surface passivation treatment is prepared by the following steps: zinc powder and grinding aids are added into a ball mill, and ball milling is carried out under nitrogen protection to obtain flaky zinc powder; the grinding aids include lubricants, surface modified ultra-fine silicon oxide and surface modifier polyamide; the amount of the grinding aids is 0.5-4.5% of the mass of the zinc powder, wherein the surface modifier polyamide is at least one of alkyl alcohol amide, polyether ester amide, erucic acid amide, stearic acid amide, oleic acid amide and modified caprolactam. By using this technical solution, the zinc powder is surface modified and coated for passivation treatment, and then is coated again with non-flammable wetting agent, so that the zinc powder is dispersed better and is not easy to burn.

[0018] As a further improvement of the present application, the lubricants include at least one of stearic acid, stearate and palmitic acid.

[0019] As a further improvement of the present application, in the grinding aids, the mass percentages of the lubricants, surface modified ultra-fine silicon oxide and surface modifier polyamide are 60-78%, 15-32% and 4-8% respectively.

[0020] As a further improvement of the present application, the zinc powder is 325-500 mesh granular zinc powder; and the drum ball mill is used for grinding for 6-12 hours.

[0021] As a further improvement of the present application, during the grinding, cold water is supplied to the cooling jacket of the ball mill, and the grinding is carried out by using steel balls with a diameter of 5-20 mm.

[0022] As a further improvement of the present application, the apparent density of the flaky zinc powder for surface passivation treatment is 0.8-1.3 g / mL, and D50 is less than 45 μm.

[0023] As a further improvement of the present application, the vacuum condition is that the vacuum degree is not less than -0.09 MPa; and the wetting agent is added by multiple spraying.

[0024] The present application also discloses a non-flammable zinc paste for zinc powder anticorrosive paint, which is prepared by using the preparation method of the non-flammable zinc paste for zinc powder anticorrosive paint.

[0025] The present application also discloses a zinc powder anticorrosive paint, which comprises the non-flammable zinc paste for zinc powder anticorrosive paint.

[0026] Compared with the prior art, the present application has the following beneficial effects:

[0027] The zinc paste prepared by the technical scheme of the present application is not flammable, reduces the harm of the dust of fine zinc powder to human body and the risk coefficient of flammability and explosiveness in the process of use, storage and transportation, and can be universally applied in oil-based epoxy zinc powder paint, water-based epoxy zinc powder paint and Dacromet and other coatings. DETAILED DESCRIPTION

[0028] The preferred embodiments of the present application are further described in detail below.

[0029] A preparation method of paste solid for zinc powder anticorrosive coating is to use surface modification and coated passivated flaky zinc powder and preferred non-flammable wetting agent for secondary coating, proportionally put into explosion-proof horizontal kneader for kneading and mixing, and get paste zinc powder material. The zinc powder material prepared by this method is non-flammable solid material after burning experiment, and can be universally applied in water-based and oil-based zinc powder paint with ≤60% of metal zinc content in coating.

[0030] Specifically includes:

[0031] Step S1, prepare surface passivated flaky zinc powder; under nitrogen protection, select 325-500 mesh particle zinc powder, and use a drum ball mill for grinding. The grinding time is 6-12h, and the grinding temperature is kept low during the grinding process by using a cooling jacket. 5-20mm steel balls are used for grinding. The dispersion and coating grinding aid agent uses a composite aid containing stearate, stearic acid, palmitic acid, surface modified ultra-fine silicon oxide, modified polyamide salt and three or more than three kinds of compound. The surface coated and passivated flaky zinc powder has a bulk density of 0.8-1.3g / mL, and the D50 of the zinc powder is less than 45μm. The amount of grinding aid agent used in the experiment is 0.5-4.5% of the weight of the zinc powder, and the mass percentage of the lubricant, the surface modified ultra-fine silicon oxide and the surface modifier polyamide is 60-78%, 15-32% and 4-8% respectively.

[0032] Step S2, adopt horizontal double-paddle kneading and stirring, check the sealing of the kneader, and the vacuum degree can reach-0.09MPa. After the flaky zinc powder is ground, it is cooled for a short time and then put into the kneader. 3.5-4.0kg of flaky zinc powder and 0.3-1.9kg of wetting liquid are put into a 5L kneader each time, and the stirring speed is 23 / 33r / min. Stir at room temperature for 5-10 minutes, then add the other half of the wetting agent into the kneader in batches, until the mixture is uniform. After complete mixing, discharge the material by turning the hopper.

[0033] The wetting agent is a high flash point non-flammable wetting agent, preferably a high flash point (flash point > 95°C) wetting agent with excellent compatibility with zinc dust paint. The preferred high flash point wetting agent includes but is not limited to one or more mixed water-soluble solvents such as dipropylene glycol butyl ether, dipropylene glycol, etc., which can be widely used in water-based zinc dust paint, water-based Dacromet coating and other water-based paint; the preferred high flash point resin includes but is not limited to one or more mixed epoxy resin and diluent, which can be widely used in oil-based zinc dust paint.

[0034] Examples 1-10

[0035] According to the above steps, the ratio of wetting agent and zinc powder is shown in Table 1. Among them, the surface passivated flaky zinc powder prepared in step S1 is prepared by the method of the prior art, specifically:

[0036] Under the protection of nitrogen, 500 mesh granular zinc powder is selected and ground by a roller ball mill. The grinding time is 7.5 h, and the grinding temperature is kept low during the grinding process by using a cooling water jacket, and 5-20 mm steel balls are used for grinding. The grinding aid of flaky zinc is 2.5% of the weight of zinc powder, and the weight ratio of the mixture of stearic acid and stearic acid: surface modified ultra-fine silicon oxide: surface modifier polyamide is 66:30:4; the bulk density of the obtained flaky zinc is 0.83 g / ml, and the D50 of the flaky zinc is <45 μm.

[0037] Examples 11-19

[0038] According to the above steps, the ratio of wetting agent and zinc powder is shown in Table 1. Among them, the surface passivated flaky zinc powder prepared in step S1 is prepared by the method of the prior art, specifically:

[0039] Under the protection of nitrogen, 325 mesh granular zinc powder is selected and ground by a roller ball mill. The grinding time is 11 h, and the grinding temperature is kept low during the grinding process by using a cooling water jacket, and 5-20 mm steel balls are used for grinding. The grinding aid of flaky zinc is 3.5% of the weight of zinc powder, and the weight ratio of the mixture of stearic acid and stearic acid ester: surface modified ultra-fine silicon oxide: surface modifier polyamide is 70:22:8; the bulk density of the obtained flaky zinc is 1.05 g / ml, and the D50 of the flaky zinc is <45 μm.

[0040] The zinc paste is tested for flammable solid classification according to GB 30000.8-2013 "Chemical Classification and Labeling Standard Part 8: Flammable Solids", and the sample can be ignited but does not burn continuously during the test process, and does not spread 200 mm in the form of flame or smoke within 20 minutes, which is not a flammable solid hazardous chemical, otherwise it is determined to be a flammable solid. The results are shown in Table 1.

[0041] Table 1

[0042]

[0043]

[0044] Comparing Example 2 with Examples 4 and 5, it can be seen that Example 2 and Examples 4 and 5 use the non-flammable wetting liquid dipropylene glycol n-butyl ether as the wetting agent to prepare zinc paste of the same non-flowable paste state of spherical zinc powder and flaky zinc powder. Under the same test conditions, the zinc paste of the spherical zinc powder of Example 2 is a flammable solid, but the zinc paste of the flaky zinc powder of Examples 4 and 5 is a non-flammable solid. The surface passivation coating of the flaky zinc powder reduces the contact between the zinc powder and oxygen in the air, and reduces the burning rate. On the other hand, the specific surface area of the flaky zinc powder of the same mass is large, and the adsorption amount of the wetting liquid is large, and the non-flammable wetting liquid further strengthens the surface coating, which has a good effect of reducing the burning rate of the zinc powder. Therefore, the non-flammable zinc powder material for zinc powder paint is preferably flaky zinc powder particles;

[0045] Comparing Examples 1, 7 and 15 with Examples 4, 5, 8, 9, 17 and 18, it can be seen that Example 1 and Examples 4 and 5 use the same wetting liquid to prepare flaky zinc materials, and the states of the zinc powder materials prepared are different, and the flammability is different. The relatively loose wet powder is a flammable solid, and the accumulated dense paste zinc paste is a non-flammable solid. The same Examples 7 to Examples 8 and 9, and Examples 15 to Examples 17 and 18. This is because the wet powder of the zinc powder is relatively loose and porous, although it is not easy to fly dust, but in the combustion process, there are gaps between the wet powder particles, and the oxygen in the gaps can promote combustion. The zinc paste in the paste state only has oxygen on the surface of the paste to support combustion, and there is no oxygen inside the zinc paste to support combustion, so it will not continue to burn, thereby further reducing the burning rate. Therefore, the state of the non-flammable zinc powder prepared is preferably a paste.

[0046] As can be seen from the examples 11, 12, 13, 16 and the comparative examples 4, 8, 9, 14, 17, 18, the examples 11, 12, 13, 16 use lower flash point flammable wetting agents, such as ethylene glycol butyl ether and a little bit of dipropylene glycol butyl ether, xylene and a little bit of n-butanol, a little bit of resin mixed liquid, and the examples 4, 8, 9, 14, 17, 18 use high flash point non-flammable wetting liquid, such as dipropylene glycol, dipropylene glycol butyl ether, high flash point epoxy resin and a little bit of xylene mixed liquid, etc., to prepare the same non-flowing solid paste state. The zinc paste of the low flash point wetting liquid belongs to flammable solid, and the zinc paste prepared by using the non-flammable high flash point wetting liquid is non-flammable solid. This is because the low flash point flammable liquid also participates in the combustion under the ignition state, which aggravates the degree of combustion. And the high flash point non-flammable liquid needs to absorb more energy to continue burning with the flame, so under the same conditions, the combustion rate is reduced, and finally the flame is quickly extinguished and the combustion is not sustainable. Therefore, the preferred wetting agent for preparing non-flammable zinc powder material is high flash point (flash point > 96℃) non-flammable such as one or more mixtures of dipropylene glycol, dipropylene glycol n-butyl ether, epoxy resin and high flash point mixed liquid.

[0047] The above is a further detailed description of the present application in combination with specific preferred embodiments, and cannot be considered as limiting the specific implementation of the present application to these descriptions. For ordinary skilled persons in the technical field to which the present application belongs, a number of simple deductions or substitutions can be made without departing from the concept of the present application, and all of them should be considered as belonging to the protection scope of the present application.

Claims

1. A method for preparing a non-flammable zinc paste for zinc powder anti-corrosion paint, characterized in that: Includes the following steps: Step S1: Prepare surface passivation treated flake zinc powder. The surface passivation treated flake zinc powder is prepared by the following steps: adding zinc powder and grinding aid into a ball mill and ball milling under nitrogen protection to obtain flake zinc powder; the grinding aid includes a lubricant, surface-modified ultrafine silica, and a surface modifier; the amount of the grinding aid is 0.5~4.5% of the zinc powder mass; wherein, the surface modifier is at least one of alkanolamide, polyether ester amide, erucamide, stearamide, oleamide, and modified caprolactam. Step S2: The flake zinc powder and wetting agent are put into a kneader and kneaded and mixed under vacuum to obtain a paste zinc powder material; the wetting agent is at least one of dipropylene glycol butyl ether, dipropylene glycol, and epoxy resin additive; the epoxy resin additive is E-20 epoxy resin. When the wetting agent is dipropylene glycol butyl ether, the mass percentage of flake zinc powder in the paste zinc powder material is 67%~82%; When the wetting agent is dipropylene glycol, the mass percentage of flake zinc powder in the paste zinc powder material is 65%~75%; When the wetting agent is E-20 epoxy resin, the mass percentage of flake zinc powder in the paste zinc powder material is 67%~80%, and the mass percentage of E-20 epoxy resin is 15~24%.

2. The method for preparing non-flammable zinc paste for zinc powder anti-corrosion paint according to claim 1, characterized in that: The lubricant includes at least one of stearic acid, stearate, and palmitic acid; In the grinding aid, the mass percentages of lubricant, surface-modified ultrafine silica, and surface modifier are 60-78%, 15-32%, and 4-8%, respectively.

3. The method for preparing non-flammable zinc paste for zinc powder anti-corrosion paint according to claim 2, characterized in that: The zinc powder is 325-500 mesh zinc powder; it is ground using a drum ball mill for 6-12 hours.

4. The method for preparing non-flammable zinc paste for zinc powder anti-corrosion paint according to claim 3, characterized in that: During the grinding process, cold water is circulated into the cooling water jacket of the ball mill, and steel balls of 5-20mm are used for grinding.

5. The method for preparing non-flammable zinc paste for zinc powder anti-corrosion paint according to claim 1, characterized in that: The loose packing density of the surface passivated zinc powder is 0.8~1.3g / mL, and D50<45μm.

6. The method for preparing non-flammable zinc paste for zinc powder anti-corrosion paint according to claim 1, characterized in that: The vacuum conditions are: a vacuum degree of not less than -0.09 MPa; the wetting agent is added by multiple sprays.

7. A non-flammable zinc paste for use in zinc powder anti-corrosion paint, characterized in that: It is prepared using the method for preparing non-flammable zinc paste for zinc powder anti-corrosion paint as described in any one of claims 1 to 6.

8. A zinc powder anti-corrosion paint, characterized in that: It includes the non-flammable zinc paste for zinc powder anti-corrosion paint as described in claim 7.

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