Laser welding shop primer and preparation method thereof

Abstract

The invention relates to the technical field of coatings, in particular to a laser welding workshop primer and a preparation method thereof. The laser welding shop primer provided by the invention has both anti-rust performance and laser welding adaptability, the weather resistance of the laser welding shop primer can reach more than 6 months, the appearance and quality of a welding seam after laser welding have no defect, and the laser welding shop primer is particularly suitable for temporary protection of an automatic laser welding steel plate. In addition, the invention further provides a preparation method of the primer for the laser welding shop, zinc powder is subjected to surface treatment based on the complexing effect of citric acid, surface coating of lanthanum silicate and samarium silicate on the zinc powder is achieved, discharging of air holes in the laser welding seam forming process is promoted through the synergistic effect, the compactness of the welding seam and the welding quality are improved, and the service life of the primer is prolonged. And the rare earth silicate coated zinc powder is uniformly dispersed in ethyl silicate hydrolysate by mixing the component A and the component B, so that the laser welding shop primer with excellent weather resistance and laser welding adaptability is prepared, and the quality of a laser welding seam is improved on the premise that the content of the zinc powder is not reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of paint, in particular to a laser welding workshop primer and a preparation method thereof. BACKGROUND

[0002] In the process of shipbuilding, first of all, the sandblasted steel plate is temporarily protected by the workshop primer, then the steel plate is cut and welded according to the design drawing, assembled into parts and sections, and finally the shipbuilding is completed through the processes of section closing, outfitting, painting and ship testing. The workshop primer plays a crucial role in the entire shipbuilding process, not only related to the corrosion resistance of the steel plate, but also related to the ablation area of the steel plate welding and the quality of the weld formation.

[0003] At present, the steel plate welding process in shipyards includes arc welding, submerged arc welding, argon arc welding, CO2 shielded welding and laser welding. Among them, laser welding is a welding technology that realizes rapid melting through high energy density light beam. Compared with traditional welding technology, laser welding has the advantages of high automation, fast welding speed, narrow weld, small heat affected zone and small welding deformation, which can greatly improve the welding efficiency of thin plates, especially suitable for the continuous processing needs of large-area thin plate components in shipbuilding. In recent years, with the development of shipbuilding technology, the application range of laser welding in shipyards has become larger and larger.

[0004] However, laser welding has the characteristics of high energy density and fast welding speed, which also leads to the problems of weld slag inclusion, poor formation and weld defects when the traditional workshop primer pre-coated steel plate is used for laser welding. These problems to some extent limit the further promotion and application of laser welding technology in the field of shipbuilding.

[0005] To improve the welding quality, many attempts have been made by those skilled in the art. Chinese patent CN102211430A disclosed a water-based automatic weldable workshop primer on October 12, 2011, by introducing conductive substances, reducing the amount of zinc in the workshop primer, thereby reducing the zinc vapor and combustion products generated during welding, thereby improving the weld formation quality. However, this scheme reduces the amount of zinc powder that plays a cathodic protection role while improving the welding quality of the workshop primer, which inevitably affects the corrosion resistance of the coating.

[0006] Chinese patent CN109943109A disclosed a water-based workshop primer composition on June 28, 2019, by modifying with carbon titanium cage resin to improve the corrosion resistance of the workshop primer and reduce the amount of zinc powder, thereby improving the welding performance of the workshop primer, but the carbon titanium cage resin introduced in this process is an organic substance that is also easy to burn and produce gas at high temperatures, which affects the weld formation.

[0007] A kind of water-based inorganic zinc-rich plant primer containing multifunctional conductive whisker and preparation method are disclosed in Chinese patent CN115785708A on March 14, 2023, which modifies the plant primer by conductive modified potassium titanate whisker, stabilizes the welding arc by potassium titanate whisker, improves the welding performance in subsequent processing, improves the welding strength and reduces the width of weld bead ablation damage, however, this scheme is only suitable for the case of using arc welding and other welding processes, and the adaptability to laser welding process is poor.

[0008] It can be seen that how to obtain a plant primer with good rust prevention performance and good laser welding adaptability is still a technical problem that needs to be solved by those skilled in the art. SUMMARY

[0009] To solve the technical problem of how to obtain a plant primer with good rust prevention performance and good laser welding adaptability, the present application provides a laser welding plant primer, which comprises component A and component B. The raw materials of component A include zinc powder, rare earth silicate, citric acid and anhydrous ethanol in a weight ratio of (20-40):(1-15):(0.1-1):(15-23). The raw materials of component B include ethyl silicate, anhydrous ethanol and hydrochloric acid. Component A and component B are compounded in a weight ratio of (2-3):1.

[0010] In an embodiment, the raw materials of component A further include xylene, pigment and filler, and thixotropic agent.

[0011] In an embodiment, the raw materials of each component are compounded in a weight ratio of: Zinc powder 20-40 parts Rare earth silicate 1-15 parts Citric acid 0.1-1 part Anhydrous ethanol 15-23 parts Xylene 5-15 parts Pigment and filler 20-42 parts Thixotropic agent 1-1.9 parts Ethyl silicate 35-50 parts Anhydrous ethanol 44-62 parts Hydrochloric acid 3-6 parts.

[0012] In an embodiment, component A contains rare earth silicate coated zinc powder.

[0013] Further, the zinc powder has a mesh number of 500-1500 mesh.

[0014] Further, the rare earth silicate includes lanthanum silicate and samarium silicate.

[0015] Further, the ratio of lanthanum silicate and samarium silicate is 1: (0.5-2) by weight.

[0016] Further, the effective component of the citric acid is greater than or equal to 99%.

[0017] Further, the color filler is any one or several of phosphorus iron powder, composite iron-titanium powder, titanium dioxide and talc powder; the thixotropic agent is any one or several of polyamide wax, organic bentonite and fumed silica; and the hydrochloric acid is an HCl solution with pH = 1.

[0018] The application also provides a preparation method of the laser welding shop primer. The preparation steps of the A component are as follows: Anhydrous ethanol and citric acid are added into a container, stirred and mixed at room temperature for 1-2 hours, and then rare earth silicate is added and stirred at (80±2) ℃ under reflux for 2-3 hours to obtain a complex system; After the complex system is cooled to room temperature, zinc powder is added and stirred for 1-2 hours to obtain a rare earth silicate-coated zinc powder dispersion; Dixylylene, color filler and thixotropic agent are added into the dispersion, and high-speed dispersion is carried out at 2500-3000 rpm for 40-60 minutes until the fineness is less than or equal to 80 μm, and the A component is obtained; The preparation steps of the B component are as follows: Silicate and anhydrous ethanol are added into a reaction kettle, heated to 35-45 ℃, and hydrochloric acid is added dropwise under stirring, and after the dropwise addition is completed, the mixture is kept for 30-50 minutes to obtain the B component; The A component and the B component are mixed in a ratio of (2-3):1 by weight, and then uniformly stirred to obtain the laser welding shop primer.

[0019] Compared with the prior art, the application has the following beneficial effects: The laser welding shop primer provided by the application has both rust prevention performance and laser welding adaptability, and the weather resistance can be more than 6 months, and the appearance and quality of the weld after laser welding are both defect-free, and the primer is particularly suitable for temporary protection of automatic laser welding steel plates, and is used in shipbuilding to solve the problem of further popularization and application of laser welding technology in the field of shipbuilding.

[0020] The application provides a preparation method of a laser welding shop primer, based on citric acid complexation, surface treatment is performed on zinc powder, surface coating of rare earth silicate on the zinc powder is realized, a component containing the rare earth silicate coated zinc powder is prepared, wherein the synergistic effect of lanthanum silicate and samarium silicate is particularly used for the rare earth silicate, the discharge of pores in the laser welding seam forming process is promoted, and the weld seam density and welding quality are improved; further, when the components A and B are mixed, the rare earth silicate coated zinc powder is uniformly dispersed in the ethyl silicate hydrolysate, the corrosion resistance of the coating is improved again, finally, the laser welding shop primer with excellent weather resistance and good laser welding adaptability is prepared, and the weld seam quality after laser welding is improved without reducing the content of zinc powder. DETAILED DESCRIPTION

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described below clearly and completely. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0022] Embodiment 1 The embodiment provides a laser welding shop primer, which is prepared by the following steps. (1) Preparation of component A S100, 15 parts of anhydrous ethanol and 0.7 parts of citric acid are added to a container, stirred and mixed at room temperature for 1 h, 10 parts of rare earth silicate is added, and heated to 80℃ and stirred to reflux for 2 h to obtain a complex system; S101, after the complex system is cooled to room temperature, 20 parts of zinc powder is added and stirred for 1 h to obtain a rare earth silicate coated zinc powder dispersion; S103, 11 parts of dimethylbenzene, 42 parts of pigment and filler, and 1.3 parts of thixotropic agent are added to the dispersion, and high-speed dispersion is performed at 2500 rpm for 40 min until the fineness is ≤80 μm, and component A is obtained.

[0023] (2) Preparation of component B According to the weight fraction, 35 parts of ethyl silicate and 62 parts of anhydrous ethanol are added to a reaction kettle, heated to 40℃, and 3 parts of hydrochloric acid is added dropwise under stirring, and after the dropwise addition is completed, the temperature is kept for 30 min to obtain component B.

[0024] (3) Preparation of the laser welding shop primer The components A and B are mixed and stirred uniformly at a weight fraction ratio of 3:1 to obtain the laser welding shop primer.

[0025] In the embodiment, the mesh number of the zinc powder is 1500 mesh.

[0026] In the embodiment, the rare earth silicate is a mixture of lanthanum silicate and samarium silicate in a weight ratio of 1:0.5.

[0027] In the embodiment, the pigment and filler is a mixture of phosphorus iron powder and titanium white powder in a weight ratio of 5:1; the thixotropic agent is organic bentonite.

[0028] Embodiment 2 The embodiment provides a laser welding workshop primer prepared by the following steps. (1) Preparation of the first component S100, 23 parts of anhydrous ethanol and 1 part of citric acid are added into a container, stirred and mixed at room temperature for 1 h, 15 parts of rare earth silicate is added, and heated to 80℃ and stirred to reflux for 2 h to obtain a complexing system; S101, after the complexing system is cooled to room temperature, 30 parts of zinc powder is added and stirred for 1 h to obtain a rare earth silicate coated zinc powder dispersion; S103, 5 parts of dimethylbenzene, 30 parts of pigment and filler, and 1 part of thixotropic agent are added into the dispersion, and high-speed dispersion is carried out at 2500 rpm for 40 min until the fineness is ≤80 μm, to obtain the first component.

[0029] (2) Preparation of the second component According to the weight fraction, 42 parts of ethyl silicate and 53.5 parts of anhydrous ethanol are added into a reaction kettle, heated to 40℃, and 4.5 parts of hydrochloric acid is added dropwise under stirring, and after the dropwise addition is completed, the temperature is maintained for 30 min to obtain the second component.

[0030] (3) Preparation of the laser welding workshop primer The first component and the second component are mixed in a weight fraction ratio of 2:1, and the mixture is uniformly stirred to obtain the laser welding workshop primer.

[0031] In the embodiment, the mesh number of the zinc powder is 1000 mesh.

[0032] In the embodiment, the rare earth silicate is a mixture of lanthanum silicate and samarium silicate in a weight ratio of 1:1.

[0033] In the embodiment, the pigment and filler is a mixture of composite iron titanium powder and talc in a weight ratio of 3:1; the thixotropic agent is fumed silica.

[0034] Embodiment 3 The embodiment provides a laser welding workshop primer prepared by the following steps. (1) Preparation of the first component S100, 22 parts of anhydrous ethanol and 0.1 parts of citric acid are added into the container, stirred and mixed at room temperature for 1 h, then 1 part of rare earth silicate is added, heated to 80℃ and stirred to reflux for 2 h to obtain a complexing system; S101, after the complexing system is cooled to room temperature, 40 parts of zinc powder is added and stirred for 1 h to obtain a rare earth silicate coated zinc powder dispersion; S103, 15 parts of dimethylbenzene, 20 parts of pigment and filler, and 1.9 parts of thixotropic agent are added into the dispersion, and high-speed dispersion is carried out at 2500 rpm for 40 min until the fineness is ≤80 μm, to obtain the component A.

[0035] (2) Preparation of component B According to the weight fraction, 50 parts of ethyl silicate and 44 parts of anhydrous ethanol are added into the reaction kettle, heated to 40℃, and 6 parts of hydrochloric acid is added dropwise under stirring, and after the dropwise addition is completed, it is kept for 30 min to obtain component B.

[0036] (3) Preparation of laser welding shop primer The component A and the component B are mixed and stirred uniformly at a weight fraction ratio of 2.3:1 to obtain the laser welding shop primer.

[0037] In this embodiment, the mesh number of the zinc powder is 500 mesh.

[0038] In this embodiment, the rare earth silicate is a mixture of lanthanum silicate and samarium silicate at a weight fraction ratio of 1:2.

[0039] In this embodiment, the pigment and filler is a mixture of phosphorus iron powder and composite iron titanium powder at a weight fraction ratio of 4:1; and the thixotropic agent is a mixture of organic bentonite and polyamide wax at a weight fraction ratio of 1:1.

[0040] The present application also provides the following comparative examples 1-5 to prepare a laser welding shop primer.

[0041] Comparative example 1 The difference between this comparative example and example 1 is that the raw materials of component A do not include rare earth silicate and citric acid; the rest of the raw materials, process parameters and operation steps are consistent with example 1 of the present application.

[0042] Comparative example 2 The difference between this comparative example and example 1 is that the raw materials of component A do not include citric acid; the rest of the raw materials, process parameters and operation steps are consistent with example 1 of the present application.

[0043] Comparative example 3 The difference between this comparative example and example 1 is that the raw materials of component A do not include rare earth silicate; the rest of the raw materials, process parameters and operation steps are consistent with example 1 of the present application.

[0044] Comparative Example 4 The difference between the present comparative example and Example 1 is that the rare earth silicate is lanthanum silicate; the rest of the raw materials, process parameters, and operation steps are consistent with those of Example 1 of the present application.

[0045] Comparative Example 5 The difference between the present comparative example and Example 1 is that the rare earth silicate is samarium silicate; the rest of the raw materials, process parameters, and operation steps are consistent with those of Example 1 of the present application.

[0046] The laser welding shop primer prepared in the above Examples 1-3 and Comparative Examples 1-5 is subjected to performance testing, and the test results are listed in Table 1.

[0047] The film thickness is tested according to GB / T 6747-2008 “Marine Shop Primer”; the drying time is tested according to GB / T 1728-2020 “Paint Film and Putty Film Drying Time Test Method”; the adhesion is tested according to GB / T 9286-2021 “Paint and Varnish Grading Test”; the weather resistance is tested according to GB / T 9276-1996 “Coating Natural Climate Exposure Test Method”; the coating change degree is tested according to GB / T 1766-2008 “Paint and Varnish Coating Aging Rating Method”; and the welding and cutting resistance is tested according to GB / T 6747-2008 “Marine Shop Primer A.2”.

[0048] The test method for laser welding adaptability is as follows: a shop primer is applied on six steel plates with a length of (1000±2) mm, a width of (200±2) mm, and a thickness of 6-10 mm by spraying, and the film thickness is 15-20 μm; after the coating is completely cured, the steel plates coated with the shop primer are subjected to flat butt welding by laser welding, the welding laser power is ≥11 kw, and the welding speed is ≥1 m / min; the appearance of the weld is observed by visual method, and the quality of the weld is observed by surface detection and X-ray detection.

[0049] Table 1: Summary of performance test results of laser welding shop primer

[0050] According to the data in Table 1, the laser welding shop primer provided in Examples 1-3 of the present application has good weather resistance, welding and cutting resistance, and laser welding adaptability, and the appearance and quality of the weld are both defect-free.

[0051] The laser welding shop primer provided by Comparative Examples 1-5 can meet the technical index requirements of weather resistance, welding and cutting, but when used for laser welding, slag inclusion, porosity defects or strip-shaped defects appear in the weld, and the coating aging degree in the weather resistance test is significantly higher than that of the inventive Examples 1-3, and obvious changes appear.

[0052] Specifically, Comparative Example 1 does not use rare earth silicate and citric acid modified zinc powder, and during laser welding, oxygen penetrates into the molten pool, and the refractory combustion products remain in the weld to form slag inclusion; Comparative Example 2 does not add citric acid for complex modification, and the combination of rare earth silicate and zinc powder is not good, and the coating effect is poor, and during laser welding, zinc rapidly volatilizes to produce a large amount of zinc vapor, which is trapped in the molten pool and cannot escape in time, resulting in porosity defects in the weld; Comparative Example 3 does not add rare earth silicate for modification, so the weld quality of laser welding is poor, and slag inclusion and strip-shaped defects appear; and in Comparative Example 4, the rare earth silicate is only lanthanum silicate, which can be complexed with citric acid to modify the zinc powder, but its chemical stability in a high-temperature oxidation environment is not as good as that of samarium silicate, so the protection effect on zinc powder during welding is also not good, and porosity defects appear in the weld; in Comparative Example 5, the rare earth silicate is only samarium silicate, which has a high melting point and a low high-temperature oxygen permeability, but its ionic conductivity is not as good as that of lanthanum silicate, so the protection effect on zinc powder is not as good as that of the synergistic effect of lanthanum silicate and samarium silicate in the inventive examples.

[0053] Although terms such as laser welding shop primer, component A, component B, rare earth silicate coated zinc powder, rust prevention performance, weather resistance, laser welding adaptability, coating aging degree, molten pool, zinc vapor, modification, coating, high-temperature oxygen permeability, ionic conductivity, etc. are used more in this paper, but the possibility of using other terms is not excluded. The use of these terms is only to facilitate the description and explanation of the essence of the invention; any interpretation as an additional limitation is contrary to the spirit of the invention.

[0054] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, and are not limited thereto; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the inventive examples.

Claims

1. A laser welding shop primer, characterized by: It includes component A and component B; The raw materials of the component A include zinc powder, rare earth silicate, citric acid, and anhydrous ethanol in a weight ratio of (20-40): (1-15): (0.1-1): (15-23); The raw materials of the component B include ethyl silicate, anhydrous ethanol and hydrochloric acid; The component A and the component B are compounded in a weight ratio of (2-3):

1.

2. The laser welding shop primer according to claim 1, characterized in that: The raw materials of the component A also include xylene, pigments, fillers and thixotropic agents.

3. The laser welding shop primer according to claim 2, characterized in that The proportion of each component in parts by weight is: Component A raw materials: 20~40 parts zinc powder 1-15 parts of rare earth silicate 0.1~1 part citric acid 15-23 parts of anhydrous ethanol 5~15 parts of xylene 20~42 parts of pigments and fillers 1~1.9 parts of thixotropic agent Raw materials for component B: 35-50 parts of ethyl silicate 44-62 parts of anhydrous ethanol 3-6 parts of hydrochloric acid.

4. The laser welding shop primer according to claim 3, characterized in that: The component A contains rare earth silicate-coated zinc powder.

5. The laser welding shop primer according to claim 4, characterized in that: The mesh size of the zinc powder is 500-1500 meshes.

6. The laser welding shop primer according to claim 4, characterized in that: The rare earth silicates include lanthanum silicate and samarium silicate.

7. The laser welding shop primer according to claim 6, characterized in that: The ratio of the lanthanum silicate to the samarium silicate is 1:(0.5-2) in parts by weight.

8. The laser welding shop primer according to claim 4, characterized in that: The effective component of the citric acid is ≥99%.

9. The laser welding shop primer according to claim 4, characterized in that: The pigment and filler is any one or more of ferrophosphorus powder, composite iron-titanium powder, titanium dioxide and talc; The thixotropic agent is any one or more of polyamide wax, organic bentonite and fumed silica; The hydrochloric acid is an HCl solution with a pH of 1.

10. A method for preparing the laser welding shop primer according to any one of claims 1 to 9, characterized in that: The preparation steps of component A are: Add anhydrous ethanol and citric acid to a container, stir and mix at room temperature for 1-2 hours, then add rare earth silicate, heat to (80±2)°C, stir and reflux for 2-3 hours to obtain a complex system; After the complexation system cools to room temperature, zinc powder is added and stirred for 1-2 hours to obtain a rare earth silicate-coated zinc powder dispersion. Add xylene, pigments, fillers and thixotropic agents to the dispersion and disperse at a high speed of 2500-3000 rpm for 40-60 min until the fineness is ≤80 μm to obtain component A. The preparation steps of component B are: Add ethyl silicate and anhydrous ethanol into a reaction kettle, heat to 35-45°C, and dropwise add hydrochloric acid under stirring. After the addition is completed, keep the temperature for 30-50 minutes to obtain component B. Component A and component B are mixed and evenly stirred in a weight ratio of (2-3):1 to obtain the laser welding workshop primer.

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