A composite surface treatment agent with defatting, dewaxing and oxide film removing functions and a preparation method thereof

Abstract

The application discloses a composite surface treatment agent with the functions of degreasing, dewaxing and oxide film removing and a preparation method thereof, and belongs to the technical field of metal surface pretreatment. The composite treatment agent is composed of 8 mL of N-1 degreasing agent product, 30 g of oxalic acid, 30 g of citric acid and the rest of deionized water per liter of working solution. The application forms a synergistic effect through the emulsification, oil removal and dewaxing effect of the N-1 degreasing agent and the complex oxide film removing effect of the oxalic acid and the citric acid, and can simultaneously complete three pretreatment processes of degreasing, dewaxing and oxide film removing, so that the process flow is greatly simplified. The organic acid compound system is mild in treatment condition, small in corrosion to the metal substrate, high in surface cleanliness after treatment, suitable for the pretreatment before electroplating and coating of various metal workpieces such as stainless steel and copper alloy, simple in formula preparation, good in medicament stability, and good in industrial application value and environmental protection benefit.

Description

Technical Field

[0001] This invention relates to the field of surface treatment technology for hardware parts, specifically to a composite surface treatment agent that combines degreasing, dewaxing, and oxide film removal functions, and its preparation method. Background Technology

[0002] In industrial settings such as hardware processing, electroplating, and coating, metal workpieces typically develop rust-preventive grease and polishing wax coatings on their surfaces after stamping, polishing, heat treatment, and transportation. This also forms an oxide film or rust layer, necessitating surface cleaning before subsequent finishing. Traditional pretreatment processes employ a step-by-step approach: first, grease is removed using an alkaline degreasing agent, then the oxide film is removed using a strong acid washing solution. For wax-containing workpieces, an additional dewaxing step is required. This results in fragmented processes, lengthy workflows, high reagent consumption, and the generation of large amounts of wastewater from multiple washing steps, leading to high treatment costs and significant environmental impact.

[0003] While some existing technologies offer combined degreasing and rust removal products, most rely on strong inorganic acids such as sulfuric acid and hydrochloric acid as their core rust-removing components. These are highly corrosive, easily causing defects such as over-corrosion and hydrogen embrittlement of the metal substrate. Furthermore, the acid mist volatilization is severe, creating a harsh working environment. Simultaneously, these products lack sufficient penetration and removal capabilities for polishing waxes, making it impossible to omit the separate dewaxing process for waxed workpieces, thus hindering true integrated treatment. In addition, some composite treatment agents have complex formulations, requiring on-site mixing of multiple additives, resulting in high formulation difficulty and poor storage stability, which is detrimental to the widespread application by small and medium-sized enterprises.

[0004] Therefore, developing an integrated degreasing, dewaxing, and oxide film removal agent with a simple formulation, comprehensive processing functions, mild reaction, and high efficiency is of great practical significance for improving the production efficiency of metal pretreatment, reducing overall costs, and practicing green manufacturing. Summary of the Invention

[0005] In view of this, the purpose of this application is to provide a composite surface treatment agent and its preparation method that have the functions of degreasing, dewaxing and removing oxide film, so as to solve the problem that the products in the prior art are highly corrosive and easily cause over-corrosion of the metal substrate.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A composite surface treatment agent that combines degreasing, dewaxing, and oxide film removal functions, contains the following components per liter of working solution: 8 mL of N-1 degreasing agent finished product; 30g of oxalic acid; 30g of citric acid; The remainder is an aqueous solvent.

[0007] Furthermore, the aqueous solvent is deionized water or pure water.

[0008] Furthermore, the N-1 degreasing agent is a commercially available surface treatment agent with functions of degreasing, dewaxing, and loosening of surface oxide film, and contains a compound system of nonionic surfactants, anionic surfactants, and weak corrosion auxiliaries.

[0009] The working principles of each component in this invention are as follows: N-1 Degreaser: As the main degreasing and waxing component, its surfactants can quickly remove grease and polishing wax from the workpiece surface through penetration, emulsification and dispersion. At the same time, its weak corrosive components can loosen the dense oxide film on the surface in advance, break the surface oil and wax barrier, create a reaction channel for the subsequent acidic rust removal components, and improve the reaction rate.

[0010] Oxalic acid: As the core component of organic acid rust removal, it can undergo complexation reaction with metal oxides to gently dissolve rust, oxide scale and passivation film. Compared with strong inorganic acids, oxalic acid has a slow and controllable corrosion rate, and the complexation products have high solubility and are not easy to precipitate in the bath, resulting in a long service life of the bath.

[0011] Citric acid: It has the dual functions of a chelating agent and a corrosion inhibitor. On the one hand, it can form a stable chelate with metal ions in the solution, break the reaction equilibrium, promote the continuous dissolution of the oxide film, and enhance the rust removal effect in conjunction with oxalic acid. On the other hand, it can form a selective adsorption protective film on the surface of the metal substrate, inhibit the corrosion of the substrate by the acid solution, avoid the risk of over-corrosion, pitting corrosion and hydrogen embrittlement, and at the same time improve the chemical stability of the bath solution.

[0012] The three components work together to create a synergistic effect: N-1 degreaser preferentially breaks down the surface oil and wax layer and loosens the oxide film, oxalic acid and citric acid penetrate and dissolve the deep oxide film together, and citric acid protects the substrate through corrosion inhibition, ultimately achieving a highly efficient and gentle treatment that combines "degreasing-waxing-oxide film removal" in one step.

[0013] Another object of the present invention is to provide a method for preparing the above-mentioned composite surface treatment agent, comprising the following steps: S1) Add 60% to 70% of the total amount of aqueous solvent to the acid-resistant preparation container, and control the liquid temperature at 20℃ to 35℃; S2) Add the weighed oxalic acid and citric acid in sequence, and stir continuously at a rate of 100~200r / min for 3~5 minutes until the solid is completely dissolved; S3) Add the formulated amount of N-1 degreasing agent to the above solution, and continue stirring for 5-10 minutes while maintaining the stirring speed until the system is uniform, clear and free of stratification; S4) Add the remaining aqueous solvent to bring the volume to the target volume, and stir for 2-3 minutes to obtain the finished working solution.

[0014] Another object of the present invention is to provide the application of the above-mentioned composite surface treatment agent for the surface pretreatment of various metal workpieces such as stainless steel, copper alloy, and carbon steel, and to simultaneously complete the degreasing, dewaxing and oxide film removal operations on the workpiece surface through immersion treatment.

[0015] Furthermore, in practical applications, the immersion treatment temperature is 30℃~50℃, and the treatment time is 5~15 minutes; after the treatment is completed, the workpiece is rinsed with running water and dried before proceeding to the next process.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. Highly integrated functions and significantly simplified processes: One agent simultaneously possesses three core functions: degreasing, dewaxing, and oxide film removal. It can replace the traditional three-step pretreatment process, reduce process switching and multiple water washing steps, shorten the overall treatment cycle by more than 40%, significantly improve production efficiency, and reduce reagent consumption and wastewater treatment costs.

[0017] 2. Significant synergistic effect and excellent treatment results: The surface penetration of N-1 degreaser and the complexation rust removal effect of oxalic acid-citric acid form a hierarchical synergistic effect, first removing oil and wax, then dissolving oxide film, with progressive and efficient reaction; after treatment, the workpiece surface is clean and free of residue, with uniform metallic luster and continuous and complete water film, which can meet the high-level pretreatment requirements of electroplating, coating and other processes.

[0018] 3. Mild reaction conditions and good matrix protection: The system uses a compound of all organic acids, with no strong acid mist volatilization, making the working environment friendly; the selective corrosion inhibition of citric acid can control the corrosion rate of the matrix at an extremely low level while efficiently removing the oxide film, with no risk of over-corrosion, pitting corrosion and hydrogen embrittlement, making it suitable for precision workpieces and a variety of metal materials.

[0019] 4. Simple and easy-to-prepare formula with strong on-site applicability: Only three raw materials need to be mixed in proportion, no additional additives are required, the on-site preparation process is simple, the tank solution has good storage stability, and it can be put into production without complicated equipment, making it suitable for processing enterprises of all sizes.

[0020] 5. Outstanding environmental performance: The organic acid system has good biodegradability, the wastewater does not contain heavy metals or strong acid pollutants, and the subsequent treatment is easy, which meets the development requirements of green manufacturing and clean production.

[0021] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the preferred embodiments of this application are described in detail below with reference to the accompanying drawings.

[0022] The above and other objects, advantages and features of this application will become more apparent to those skilled in the art from the following detailed description of specific embodiments in conjunction with the accompanying drawings. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In all drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0024] Figure 1 This is the formula table for the present invention; Figure 2 This is a flowchart illustrating the preparation process of the present invention; Figure 3 These are comparative diagrams of embodiments of the present invention. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. In the following description, specific details such as specific configurations and components are provided merely to help fully understand the embodiments of this application. Therefore, those skilled in the art should understand that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of this application. In addition, for clarity and brevity, descriptions of known functions and structures are omitted in the embodiments.

[0026] Furthermore, reference numerals and / or letters may be repeated in different examples within this application. Such repetition is for the purpose of simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or settings discussed.

[0027] In this article, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, B exists alone, and A and B exist simultaneously. The term " / and" in this article describes another type of relationship between related objects, indicating that two relationships can exist. For example, A / and B can mean: A exists alone, and A and B exist alone. In addition, the character " / " in this article generally indicates that the related objects before and after it are in an "or" relationship.

[0028] It should also be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion.

[0029] Please see Figure 1-3 This invention provides a technical solution for a composite surface treatment agent that combines degreasing, dewaxing, and oxide film removal functions, as well as a method for its preparation: Example 1

[0030] This embodiment provides a composite surface treatment agent that combines degreasing, dewaxing, and oxide film removal functions. The composition of each 1L working solution is as follows: 8 mL of N-1 degreasing agent finished product; 30g of oxalic acid; 30g of citric acid; Add deionized water to a final volume of 1000 mL.

[0031] The preparation method is as follows: (1) Add 650mL of deionized water to the PP plastic preparation tank and control the water temperature at 25℃; (2) Add 30g of oxalic acid and 30g of citric acid in sequence, and stir at a rate of 150r / min for 4 minutes until the solid is completely dissolved and the solution is clear; (3) Add 8 mL of N-1 degreasing agent product, and continue stirring for 8 minutes while maintaining the stirring speed until the solution is uniform, clear and without layering. (4) Add deionized water to bring the volume to 1000 mL, then stir for 2 minutes to obtain the finished working solution.

[0032] Processing applications: Take a 304 stainless steel test piece with rust-preventive oil, polishing wax and rolled oxide film on the surface, immerse it in the above working solution, control the treatment temperature at 40℃, and immerse it for 10 minutes; after taking it out, rinse it with running water for 30 seconds and blow it dry with cold air.

[0033] Effect testing: The grease and wax on the surface of the test piece were completely removed, the oxide film was completely dissolved, and the surface showed a uniform silvery-white metallic luster; the degreasing effect was tested by the water film method, the water film was continuous and intact, and the degreasing grade reached 0; the corrosion of the substrate was observed by metallographic microscope, the corrosion rate was less than 2g / m²・h, and there were no pitting or over-corrosion traces, which met the requirements of precision electroplating pretreatment.

[0034] Example 2

[0035] This embodiment provides a composite surface treatment agent that combines degreasing, dewaxing, and oxide film removal functions. The composition of each 1L working solution is as follows: 8 mL of N-1 degreasing agent finished product; 30g of oxalic acid; 30g of citric acid; Add deionized water to a final volume of 1000 mL.

[0036] The preparation method is the same as in Example 1.

[0037] Processing applications: Take an H62 brass workpiece with surface oxidation discoloration and stretching oil, immerse it in the above working solution, control the treatment temperature at 35℃, and immerse it for 7 minutes; after taking it out, wash it with water and blow it dry.

[0038] Results inspection: The oxide color on the workpiece surface has completely faded, the stretching oil has been thoroughly removed, the surface has regained the original metallic luster of brass, there is no corrosion or darkening, and the surface roughness has not changed significantly, meeting the pretreatment requirements for subsequent electroplating and rack plating.

[0039] Comparative Example 1 The difference between this comparative example and Example 1 is that N-1 degreasing agent is not added, and only an aqueous solution containing 30 g / L oxalic acid and 30 g / L citric acid is prepared.

[0040] Stainless steel test pieces were treated under the same conditions as in Example 1. The results showed that the grease and wax on the surface of the test pieces could not be effectively removed, the oxide film was only partially dissolved, and there were large areas of oil stains and residual wax on the surface after treatment. The rust removal was incomplete and could not meet the cleanliness requirements of the pretreatment.

[0041] Comparative Example 2 The difference between this comparative example and Example 1 is that oxalic acid and citric acid are not added, and only an aqueous solution containing 8 mL / L N-1 degreasing agent is prepared.

[0042] Stainless steel test pieces were treated under the same conditions as in Example 1. The results showed that the grease and wax on the surface of the test pieces were basically removed, but the oxide film did not dissolve significantly, and there was still a dark oxide layer on the surface, which could not meet the process requirements for rust removal and oxide film removal.

[0043] As can be seen from the above embodiments and comparative examples, the present invention achieves integrated and efficient treatment of degreasing, dewaxing, and oxide film removal through the synergistic combination of N-1 degreasing agent, oxalic acid, and citric acid. All three are indispensable, and the treatment effect is qualitatively improved compared with single or two-component treatment.

[0044] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention; any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0045] The above description is merely a preferred embodiment of the present invention and does not limit the scope of protection of the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any changes, modifications, substitutions, integrations, and parameter alterations to these embodiments within the spirit and principles of the present invention, achieved through conventional substitutions or by achieving the same function without departing from the principles and spirit of the present invention, fall within the scope of protection of the present invention.

Claims

1. A composite surface treatment agent that combines degreasing, dewaxing, and oxide film removal functions, characterized in that, Each unit volume of working fluid consists of the following components: 8 mL of N-1 degreasing agent finished product; 30g of oxalic acid; 30g of citric acid; The remainder is an aqueous solvent.

2. The composite surface treatment agent according to claim 1, characterized in that, The aqueous solvent is deionized water or pure water.

3. The composite surface treatment agent according to claim 1, characterized in that, The N-1 degreasing agent is a finished surface treatment agent with functions of degreasing, dewaxing, and loosening the surface oxide film.

4. A method for preparing the composite surface treatment agent according to claim 1, characterized in that, Includes the following steps: S1) Add 60% to 70% of the total amount of aqueous solvent to the preparation container, and control the liquid temperature at 20℃ to 35℃; S2) Add the weighed oxalic acid and citric acid in sequence, and continue stirring until the solid is completely dissolved; S3) Add N-1 degreasing agent product to the above solution and continue stirring for 5-10 minutes until the system is evenly mixed; S4) Add the remaining aqueous solvent to bring the volume to the target volume, stir well, and the finished working solution is obtained.

5. The preparation method according to claim 4, characterized in that, In step (2), the stirring rate is 100~200 r / min and the stirring time is 3~5 minutes.

6. The application of the composite surface treatment agent according to claim 1, characterized in that, Used for surface pretreatment of metal workpieces, it simultaneously completes degreasing, dewaxing, and oxide film removal on the workpiece surface through immersion treatment.

7. The application according to claim 6, characterized in that, The immersion treatment temperature is 30℃~50℃, and the treatment time is 5~15 minutes.

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