Environmentally friendly paint stripper and preparation method thereof

Abstract

The invention discloses an environmentally friendly paint stripper and a preparation method thereof, wherein the raw materials include 10 to 50 parts of a main solvent, 5 to 20 parts of a cosolvent, 5 to 20 parts of a surfactant, 2 to 15 parts of a promoter, 1 to 5 parts of a flocculant, 1 to 5 parts of a thixotropic agent, and a balance of water by weight, wherein the surfactant is a combination of any one or more of a Bola-type fluorinated phosphate surfactant and isooctyl alcohol polyoxyethylene ether monophosphate, a fatty alcohol polyoxyethylene ether phosphate, an alkyl phosphate, an alkylphenol polyoxyethylene ether phosphate, a long-chain fatty alcohol polyoxyethylene ether, an alkylphenol polyoxyethylene ether, and a fatty acid polyoxyethylene ester. The advantage is that the existing paint strippers have the advantages of being highly toxic, volatile, not easy to clean after paint stripping, affecting recoating adhesion, and having a narrow applicable environment, and provide a non-toxic and environmentally friendly, non-toxic and environmentally friendly, high-efficiency paint stripper that can be used in an environment of 5°C-70°C.

Description

Technical Field

[0001] The invention belongs to the field of electroplating, and particularly relates to an environmentally friendly paint stripper and a preparation method thereof. Background Art

[0002] Paint film can protect the substrate and beautify the appearance. It is widely used in industrial manufacturing, construction, metallurgy, shipbuilding, transportation and other fields. However, sometimes due to application requirements, the paint film needs to be completely removed. At this time, paint strippers are needed to play a role. The function of paint strippers is to destroy the spatial structure of the paint film or the bonding force between the paint film and the substrate. Paint strippers are liquids made of solvents with high solubility and have a strong ability to dissolve paint films. The solvent molecules in the paint stripper penetrate into the molecular segments of the paint film polymer, and the paint film dissolves; or the volume of the polymer macromolecules increases and internal stress is generated. When the internal stress is sufficient to destroy the bonding force between the paint film and the substrate, the paint film has fallen off. Paint strippers can remove a wide range of coatings, and are suitable for various coatings such as acrylic, epoxy, polyester, polyurethane, alkyd, and nitro.

[0003] The main component of traditional paint strippers is dichloromethane, which is highly volatile and toxic. With the attention of the state and society to environmental protection and safety, paint strippers with dichloromethane as the main component can no longer meet the industry's demand for environmentally friendly paint strippers. At present, water-based paint strippers are mostly converted to benzyl alcohol as the main component, supplemented by functional components such as thickeners, anti-volatile agents, penetrants and surfactants, and their volatility and toxicity are relatively small, which has become a new development trend. However, there are still some problems with water-based paint strippers. For example, paraffin as an anti-volatile agent is easy to remain on the surface of the substrate, making the surface appearance of the substrate look flowery, and it will also affect the adhesion of the paint film of the substrate to be re-coated; the storage stability of the oil-in-water system is not good, and it is easy to stratify; the paint stripping effect of the water-based system is not ideal, etc. Therefore, it is of great significance to develop a water-based environmentally friendly paint stripper with good paint stripping effect, high stability, and no effect on the appearance and re-coating of the substrate, and it is also an important research topic for researchers in this field.

[0004] Patent CN115820030B discloses a highly efficient paint stripper and a method for making the same. The paint stripper of the invention is mainly composed of a main paint stripper and an accelerator. Dichloromethane is used as a main solvent, hydrogen peroxide is used as an accelerator, and a new stabilizer is synthesized to improve the stability of hydrogen peroxide, thereby improving the problems of low storage stability and low paint stripping efficiency of the paint stripper caused by adding hydrogen peroxide as an accelerator to the existing dichloromethane paint stripper.

[0005] Patent CN110229554A discloses an alkaline environmentally friendly paint stripper and its use method. The main components of the paint stripper do not contain volatile chlorinated or other halogen organic solvents, and do not contain various acids. It mainly contains alcohol, phenol, surfactant, thickener and paraffin. It can dissolve the paint film under neutral conditions, making the paint film easy to remove, without damaging the workpiece, without polluting the environment, and can be reused.

[0006] Patent CN104151918A discloses a neutral environmentally friendly paint stripper, which is a mixed solution composed of a main solvent, a volatility retarder, an activator, a co-solvent, an emulsifier, a corrosion inhibitor, a penetrant, an alkane deodorizer, and a thickener. The invention can effectively and thoroughly remove the electrophoretic coating on metal parts of complex shapes, with a paint stripping efficiency of ≥98%. It is non-corrosive to metals, wood, cement, etc., has a wide range of applications, no irritating odor, low volatility, little harm to the human body and environmental pollution, high stability, and is easy to clean.

[0007] Patent CN113150603A discloses a strong paint stripper, which uses a mixture of dimethyl sulfoxide and ethylene glycol acetate to form a complete and efficient paint stripper. The surfactant can significantly reduce the surface tension of the coating. The penetrant can further reduce the surface tension of the coating while allowing the mixture of dimethyl sulfoxide and ethylene glycol acetate to penetrate into the coating well, allowing the coating to fall off faster. It does not use dichloromethane and phenols, and is safer during use, which not only ensures the physical and mental health of construction workers, but also protects the construction environment.

[0008] Patent CN108976894B discloses a paint stripper and a paint stripping method for easily separating UV ink films on metal surfaces. The paint stripper has benzyl alcohol, N-methyl-2-pyrrolidone, acetone, acetic acid, and OP-10 as main ingredients. After the UV ink film and the metal are separated, it will not adhere to the metal surface again, which is convenient for subsequent filtration and removal of the separated ink film, and the metal substrate will not be damaged. Summary of the invention

[0009] The purpose of the present invention is to provide an environmentally friendly paint stripper and a preparation method thereof, so as to overcome the problems of existing paint strippers, such as high toxicity, fast volatilization speed, paraffin wax causing difficulty in cleaning after paint stripping, affecting recoating adhesion, and narrow applicable environment, and to provide a non-toxic, environmentally friendly and efficient paint stripper that can be used in an environment of 5°C-70°C.

[0010] The invention discloses an environmentally friendly paint stripper. The raw materials thereof include, by weight, 10 to 50 parts of a main solvent, 5 to 20 parts of a cosolvent, 5 to 20 parts of a surfactant, 2 to 15 parts of a promoter, 1 to 5 parts of a flocculant, 1 to 5 parts of a thixotropic agent, and the balance of water. The surfactant is a Bola-type fluorinated phosphate surfactant and any one or a combination of several of isooctyl alcohol polyoxyethylene ether monophosphate, fatty alcohol polyoxyethylene ether phosphate, alkyl phosphate, alkylphenol polyoxyethylene ether phosphate, long-chain fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, and fatty acid polyoxyethylene ester.

[0011] Furthermore, the Bola-type fluorinated phosphate surfactant is a Bola-type fluorinated phosphate surfactant obtained by quantitatively esterifying perfluoropolyether diol (terminated hydroxyl perfluoropolyether) with dicarboxylic acid and then reacting with a phosphating agent.

[0012] Furthermore, the main solvent is a high-boiling point ether substance, including propylene glycol phenyl ether, propylene glycol butyl ether, propylene glycol propyl ether, dipropylene glycol butyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monomethyl ether, and tripropylene glycol n-butyl ether.

[0013] Furthermore, the cosolvent includes any one or a combination of ethanol, glycerol, propylene glycol, butanol, pentanol, hexanol, ethylene glycol, benzyl alcohol, acetone, dimethyl sulfoxide, and N-methylpyrrolidone.

[0014] Furthermore, the promoter is one or a combination of sodium hydroxide, potassium hydroxide, calcium hydroxide, and magnesium hydroxide, the flocculant is one or a combination of polyferric sulfate, polyaluminum chloride, and polyacrylamide, and the thixotropic agent is any one or a combination of modified starch, carboxymethyl cellulose, hydroxyethyl cellulose, and fumed silica.

[0015] Furthermore, the main solvent is 30 parts of dipropylene glycol monomethyl ether and 10 parts of propylene glycol propyl ether, the co-solvent is 20 parts of benzyl alcohol, 5 parts of dimethyl sulfoxide, 8 parts of Bola-type fluorinated phosphate surfactant, 3 parts of alkylphenol polyoxyethylene ether phosphate, the promoter is 6 parts of sodium hydroxide, the flocculant is 3 parts of polyacrylamide, and the thixotropic agent is 2 parts of fumed silica.

[0016] A method for preparing an environmentally friendly paint stripper comprises preparing a Bola-type fluorinated phosphate surfactant; step 1, adding 100 ml of dimethyl sulfoxide, 7.36 g of glutamic acid (0.05 mol), 3 g of concentrated H 2 SO 4, while stirring, the temperature was raised to 85°C, and the temperature was kept stable. 100 g of perfluoropolyether diol (terminated hydroxyl perfluoropolyether) (molecular weight 1000, 0.1 mol) was slowly added dropwise through a constant pressure dropping funnel to carry out esterification reaction. The water generated during the reaction flowed into the water separator through a straight condenser. The temperature was maintained at 85°C and the reaction was carried out for 18 hours. The reaction product was introduced into a single-mouth bottle and placed on a rotary evaporator for rotary evaporation to remove water to obtain product a;

[0017] Step 2: The system adopts an ice-water bath, pours the obtained product a into a 500ml three-necked flask, stirs, and when cooled to 0-5°C, slowly drops 15.33g of phosphorus oxychloride (0.1mol) through a constant pressure dropping funnel. After the addition is completed, continue the ice-water bath reaction for 5h to obtain product b. The reaction device is connected to a bend pipe and passed into a 30% sodium hydroxide aqueous solution for absorption. The reaction progress is monitored by detecting the concentration of the NaOH absorption solution;

[0018] Step 3: This step is to hydrolyze the remaining -P-Cl into -P-OH. 200 ml of deionized water is directly added to the reaction product b in step 2, and the temperature is raised to 70° C. with stirring. The hydrolysis reaction is carried out for 2 hours. The reaction device in this step is also connected to a bend pipe, and the generated HCl gas is passed into a 30% sodium hydroxide aqueous solution for absorption. The reaction progress is determined by detecting the concentration of the NaOH absorption solution. When the concentration of the NaOH absorption solution no longer changes, the heating is stopped;

[0019] The obtained Bola type fluorinated phosphate surfactant is used to prepare an environmentally friendly paint stripper.

[0020] Furthermore, the obtained Bola-type fluorinated phosphate surfactant is used to prepare an environmentally friendly paint stripper, and the steps are as follows: add water to a reaction kettle, add a thixotropic agent while stirring, and after the thixotropic agent is dispersed and dissolved, add the main solvent to the reaction kettle in sequence, stir evenly, then add the Bola-type fluorinated phosphate surfactant and alkylphenol polyoxyethylene ether phosphate, stir for 15 minutes, add an accelerator, wait for it to be completely dissolved, add a flocculant and water, stir evenly, and obtain a finished paint stripper.

[0021] Furthermore, the main solvent is a high-boiling point ether substance, including propylene glycol phenyl ether, propylene glycol butyl ether, propylene glycol propyl ether, dipropylene glycol butyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monomethyl ether, and tripropylene glycol n-butyl ether; the co-solvent includes any one or a combination of ethanol, glycerol, propylene glycol, butanol, pentanol, hexanol, ethylene glycol, benzyl alcohol, acetone, dimethyl sulfoxide, and N-methylpyrrolidone.

[0022] Furthermore, by weight, the main solvent is 10 to 50 parts, the co-solvent is 5 to 20 parts, the surfactant is 5 to 20 parts, the accelerator is 2 to 15 parts, the flocculant is 1 to 5 parts, the thixotropic agent is 1 to 5 parts, and the balance is water.

[0023] The present invention is beneficial in that:

[0024] The paint film is easy to clean. In practical applications, when the electroplating rack or reworked workpiece enters the paint stripper tank for immersion, due to the low surface tension and appropriate viscosity, the paint stripper component quickly wets and spreads on the surface of the electroplating rack or reworked workpiece, carrying the promoter and solvent to be adsorbed on the surface of the paint film, and molecular penetration is carried out to destroy the ester bonds in the paint film polymer, so that the paint film wrinkles in a short time and detaches from the surface of the electroplating rack or reworked workpiece. At the same time, the flocculant in the component complexes the paint film fragments that have been removed and settles to the bottom of the paint stripper tank. When cleaning the paint stripper tank regularly, it is only necessary to pump the upper layer of paint stripper into the storage barrel, clean the bottom layer of paint film solids, and then pour in the extracted paint stripper.

[0025] The system has high stability. The specially prepared Bola-type phosphate ester fluorinated surfactant in the paint stripper component is hydrophilic at its two end groups, contains both hydrophilic segments and lipophilic segments, can be dissolved in water, has good compatibility with each component, and can assist other components of the paint stripper to dissolve better in water. In addition, due to the particularity of the molecular structure of the Bola-type phosphate ester fluorinated surfactant (containing carbon-fluorine bonds-stable structure and phosphate-alkali resistance), it has excellent thermal stability and alkali resistance. In addition, the main solvents used in the paint stripper of the present invention are all high-boiling point solvents, so that the paint stripper can be heated during the application process, and the volatility is very low, which reduces the content of volatile organic substances in the working environment and protects the health of front-line workers. During the entire paint stripping process, heating can accelerate the molecular movement of the paint stripper components, which is convenient for accelerating the shedding of the paint film. Furthermore, in the paint stripper solution, due to the low surface energy characteristics of the surfactant, some Bola-type phosphate ester fluorinated surfactants will automatically migrate to the surface of the solution. The two end groups (-P(OH)3) in the molecule will automatically face the paint stripper solution due to their hydrophilicity, while the hydrophobic segments of the Bola-type phosphate ester fluorinated surfactant will face the air, thereby forming a monolayer lipid film on the surface of the paint stripper solution to exert its thermal stability.

[0026] Fast paint stripping speed: common acrylate-containing coatings can be dissolved within 20 minutes. Since the paint stripper of the present invention uses alkali as a promoter, the bimolecular alkali is highly destructive to the ester bond of the paint film, so the pH of the entire paint stripper is alkaline. The Bola-type phosphate ester fluorinated surfactant contains a phosphate group, which has better alkali resistance than common surfactants on the market, and can adapt to the alkaline environment in the paint stripper components of the present invention. They cooperate with each other to improve the breaking efficiency of the ester bond of the paint film and shorten the desorption time.

[0027] Safety and environmental protection: high flash point, non-toxic, and does not contain methylene chloride.

[0028] Low volatility: The thermally stable monolayer lipid film formed on the surface of the paint stripper solution by the Bola-type fluorinated phosphate surfactant with a special structure reduces the overall volatility of the paint stripper during the temperature-raising paint stripping process.

[0029] Wide application environment: It can be used in an environment of 5℃-70℃ and is not affected by high humidity and high heat environment.

[0030] Easy to rinse with water: The present invention does not contain the volatility inhibitor paraffin and thickener polymethyl methacrylate and other substances contained in the traditional paint stripping. The residue after paint stripping can be easily rinsed with water without affecting the adhesion of the re-coating paint film of the workpiece.

[0031] Wide range of applications: Mainly used for stripping the outer paint film of electroplating hangers and reworked workpieces in the electroplating production process, and can also be used in other places where the surface paint film needs to be removed. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0033] Example 1, an environmentally friendly paint stripper, comprising the following raw materials in weight proportions: 30 parts of dipropylene glycol monomethyl ether, 10 parts of propylene glycol propyl ether, 20 parts of benzyl alcohol, 5 parts of dimethyl sulfoxide, 8 parts of Bola-type fluorinated phosphate surfactant, 3 parts of alkylphenol polyoxyethylene ether phosphate, 6 parts of sodium hydroxide, 3 parts of polyacrylamide, 2 parts of fumed silica, and the balance of water;

[0034] The preparation method of Bola type fluorinated phosphate surfactant is as follows:

[0035] Step 1: Add 100 mL of dimethyl sulfoxide, 7.36 g of glutamic acid (0.05 mol), and 3 g of concentrated H2SO4 to a 500 ml three-necked flask, stir and heat the mixture to 85°C, keep the temperature stable, and slowly drop 100 g of perfluoropolyether diol (hydroxyl-terminated perfluoropolyether) (molecular weight 1000, 0.1 mol) through a constant pressure dropping funnel to carry out esterification reaction. The water generated during the reaction flows into the water separator through a straight condenser tube, and the temperature is maintained at 85°C for 18 hours. The reaction product is introduced into a single-necked bottle and placed on a rotary evaporator for rotary evaporation to remove water to obtain product a.

[0036] Step 2: Pour the product a obtained by reaction (1) into a 500 ml three-necked flask in an ice-water bath, stir, and slowly drop 15.33 g of phosphorus oxychloride (0.1 mol) through a constant pressure dropping funnel when the temperature is cooled to 0-5°C. After the dropwise addition is completed, continue the ice-water bath reaction for 5 h to obtain product b. This reaction device is connected to a curved pipe and passed into a 30% sodium hydroxide aqueous solution for absorption. The reaction progress is monitored by detecting the concentration of the NaOH absorption liquid.

[0037] Step 3: This step is to hydrolyze the remaining -P-Cl into -P-OH. Add 200 ml of deionized water directly to the reaction product in step 2, stir and heat to 70°C, and hydrolyze for 2 hours. The reaction device in this step is also connected to a bend pipe, and the generated HCl gas is passed into a 30% sodium hydroxide aqueous solution for absorption. The reaction progress is determined by detecting the concentration of the NaOH absorption solution. When the concentration of the NaOH absorption solution no longer changes, stop heating.

[0038] The preparation method of the above-mentioned environmentally friendly paint stripper comprises the following steps:

[0039] Add an appropriate amount of water to the reactor, add fumed silica while stirring, and after the fumed silica is dispersed and dissolved, add dipropylene glycol monomethyl ether, propylene glycol propyl ether, benzyl alcohol, and dimethyl sulfoxide to the reactor in sequence and stir evenly. Then add Bola-type fluorinated phosphate surfactant and alkylphenol polyoxyethylene ether phosphate, stir for 15 minutes, add sodium hydroxide, wait until it is completely dissolved, add flocculant and the remaining amount of water, stir evenly, and the finished paint stripper is obtained.

[0040] The application of the paint stripper of the present invention is to pour a proper amount of the paint stripper into the paint stripping tank of the electroplating production line, and when the electroplating hanger or workpiece that needs to be stripped is immersed in the paint stripping tank, the ultrasonic vibration of the paint stripping tank is turned on, the paint stripping work is carried out for 10-20 minutes, the hanger is operated, the workpiece is taken out, and enters the next water washing tank for rinsing.

[0041] Example 2, an environmentally friendly paint stripper, comprising the following raw materials in weight proportions: 28 parts of dipropylene glycol monopropyl ether, 10 parts of propylene glycol phenyl ether, 10 parts of N-methyl pyrrolidone, 5 parts of dimethyl sulfoxide, 10 parts of Bola-type fluorinated phosphate surfactant, 5 parts of isooctyl alcohol polyoxyethylene ether monophosphate, 2 parts of sodium hydroxide, 2 parts of polyacrylamide, 1 part of polymerized ferric sulfate, 1 part of fumed silica, 2 parts of hydroxyethyl cellulose, and the balance of water;

[0042] The preparation method of Bola type fluorine-containing phosphate surfactant is the same as that in Example 1.

[0043] The preparation method of the above-mentioned environmentally friendly paint stripper comprises the following steps:

[0044] Add an appropriate amount of water to the reactor, add fumed silica while stirring, and after the fumed silica is dispersed and dissolved, add dipropylene glycol monomethyl ether, propylene glycol propyl ether, benzyl alcohol, and dimethyl sulfoxide to the reactor in sequence and stir evenly. Then add Bola-type fluorinated phosphate surfactant and alkylphenol polyoxyethylene ether phosphate, stir for 15 minutes, add sodium hydroxide, wait until it is completely dissolved, add flocculant and the remaining amount of water, stir evenly, and the finished paint stripper is obtained.

[0045] The application of the paint stripper of the present invention is to pour a proper amount of the paint stripper into the paint stripping tank of the electroplating production line, and when the electroplating hanger or workpiece that needs to be stripped is immersed in the paint stripping tank, the ultrasonic vibration of the paint stripping tank is turned on, the paint stripping work is carried out for 10-20 minutes, the hanger is operated, the workpiece is taken out, and enters the next water washing tank for rinsing.

[0046] Example 3, an environmentally friendly paint stripper, comprising the following raw materials in weight proportions: 20 parts of tripropylene glycol n-butyl ether, 10 parts of dipropylene glycol monomethyl ether, 15 parts of propylene glycol butyl ether, 8 parts of benzyl alcohol, 6 parts of butanol, 3 parts of dimethyl sulfoxide, 12 parts of Bola-type fluorinated phosphate surfactant, 5 parts of fatty alcohol polyoxyethylene ether phosphate, 3 parts of alkylphenol polyoxyethylene ether, 15 parts of sodium hydroxide, 2 parts of polyacrylamide, 1 part of polyaluminium chloride, 1 part of carboxymethyl cellulose, 2 parts of hydroxyethyl cellulose, and the balance of water;

[0047] The preparation method of Bola type fluorine-containing phosphate surfactant is the same as that in Example 1.

[0048] The preparation method of the above-mentioned environmentally friendly paint stripper comprises the following steps:

[0049] Add an appropriate amount of water to the reactor, add fumed silica while stirring, and after the fumed silica is dispersed and dissolved, add dipropylene glycol monomethyl ether, propylene glycol propyl ether, benzyl alcohol, and dimethyl sulfoxide to the reactor in sequence and stir evenly. Then add Bola-type fluorinated phosphate surfactant and alkylphenol polyoxyethylene ether phosphate, stir for 15 minutes, add sodium hydroxide, wait until it is completely dissolved, add flocculant and the remaining amount of water, stir evenly, and the finished paint stripper is obtained.

[0050] The application of the paint stripper of the present invention is to pour a proper amount of the paint stripper into the paint stripping tank of the electroplating production line, and when the electroplating hanger or workpiece that needs to be stripped is immersed in the paint stripping tank, the ultrasonic vibration of the paint stripping tank is turned on, the paint stripping work is carried out for 10-20 minutes, the hanger is operated, the workpiece is taken out, and enters the next water washing tank for rinsing.

[0051] The surfactant with special structure is a Bola-type fluorinated phosphate surfactant and any one or a combination of polyoxyethylene isooctyl alcohol ether monophosphate, polyoxyethylene fatty alcohol ether phosphate, alkyl phosphate, polyoxyethylene alkylphenol ether phosphate, long-chain polyoxyethylene fatty alcohol ether, polyoxyethylene alkylphenol ether, polyoxyethylene fatty acid ester;

[0052] Bola type fluorinated phosphate surfactant is a Bola type fluorinated phosphate surfactant obtained by quantitative esterification of perfluoropolyether diol (hydroxyl-terminated perfluoropolyether) with dicarboxylic acid and then reacting with a phosphating agent. The specific reaction equations for each step are as follows:

[0053]

[0054]

[0055] .

[0056] Perfluoropolyether diol (hydroxyl-terminated perfluoropolyether) is a commercially available product purchased from Hubei Xinyuhong Biopharmaceutical Technology Co., Ltd. and Wuhan Kemik Biopharmaceutical Technology Co., Ltd., with a molecular weight selected from 500-1500.

[0057] The dibasic acid was glutamic acid, which was a commercially available product purchased from Sigma-Aldrich (Shanghai) Trading Co., Ltd.

[0058] The esterification reaction conditions are to add an appropriate amount of concentrated sulfuric acid as a catalyst, the reaction temperature is 70-90°C, and the reaction time is 12-24h.

[0059] The phosphating reaction conditions are as follows: phosphorus oxychloride is added to dimethyl sulfoxide solvent in an ice-water bath, stirred evenly, and then the phosphorus oxychloride / dimethyl sulfoxide solution is added dropwise to the product obtained in reaction (1) while stirring. After the addition is completed, the reaction is continued in an ice-water bath for 4-6 hours.

[0060] The post-treatment process is as follows: add excess deionized water to the solution after the reaction in step (2), raise the temperature to 70°C and perform hydrolysis reaction for 2 hours.

[0061] During reaction (2) and reaction (3), the HCl gas generated during the reaction is introduced into the NaOH aqueous solution for absorption, and the reaction progress is determined by detecting the concentration of the NaOH absorption solution. During reaction (3), heating is stopped when the concentration of the NaOH absorption solution no longer changes.

[0062] The water produced in reaction (1) is removed by a water separator during the reaction. After the reaction, the solution is placed in a rotary evaporator to remove water. The HCl gas produced in reactions (2) and (3) is passed into a reagent bottle containing an aqueous NaOH solution and absorbed by the aqueous NaOH solution. The HCl dissolved in the solution has no effect on the overall formulation of the paint stripper. After the surfactant solution is added to the paint stripper formulation, the small amount of concentrated H 2 SO 4And HCl will be neutralized with the sodium hydroxide in the formula. Therefore, each reaction process of the surfactant of the present invention does not require complicated post-treatment procedures, which is convenient for industrial production.

[0063] The accelerator is one or a combination of sodium hydroxide, potassium hydroxide, calcium hydroxide and magnesium hydroxide;

[0064] The flocculant is one or a combination of polyferric sulfate, polyaluminium chloride and polyacrylamide;

[0065] The thixotropic agent is any one or a combination of modified starch, carboxymethyl cellulose, hydroxyethyl cellulose, and fumed silica;

[0066] Water is tap water or deionized water.

[0067] The application of the present invention is to pour a proper amount of paint stripper into the paint stripping tank of the electroplating production line, and when the electroplating hanger or workpiece that needs to be stripped is immersed in the paint stripping tank, the ultrasonic vibration of the paint stripping tank is turned on, the paint stripping work is carried out for 10-20 minutes, the hanger is operated, the workpiece is taken out, and enters the next water washing tank for rinsing.

[0068] The present invention tests the viscosity, paint stripping time (min), volatility, effect on substrate re-coating, and storage stability of the examples and comparative examples.

[0069] Among them, viscosity: a viscometer is used to measure the viscosity of the paint stripper at different thickener addition amounts, and the most suitable viscosity is about 15 mPa·s.

[0070] Paint stripping time (min): The paint film on the surface of the aluminum alloy substrate was stripped using the paint strippers of the examples and comparative examples at a temperature of 5-60° C. The time when the paint film was completely detached was recorded as the paint stripping time.

[0071] Volatility: Use weighing measurement method. First, record the weight of the workpiece just put into the paint stripper solution tank. After the paint film is completely removed, weigh the weight of the paint stripper solution tank again after paint stripping. The difference between the weight before and after is the volatile amount of the solution.

[0072] *100%

[0073] Impact on re-coating of substrate: The aluminum alloy substrates whose surface paint films were removed by the paint strippers of the embodiment and the comparative example were respectively washed and dried, and then re-coated with acrylic polyurethane paint films, and their adhesion levels were tested according to GB / T9286 standard.

[0074] Storage stability: The paint strippers of the embodiment and the comparative example were placed in a constant temperature and humidity chamber at the same time and stored at a certain temperature, and the delamination was observed at 0 days, 7 days, 15 days and 30 days. Storage stability tests were performed at 30°C, 50°C and 70°C respectively. The test indicators are shown in Table 1.

[0075] Table 1 Performance indicators of examples and comparative examples

[0076]

[0077] Examples 1-3 are examples in which a Bola type surfactant is added;

[0078] In the formula components of Comparative Example 1, the Bola type surfactant was removed and replaced with an equal amount of water;

[0079] In both Comparative Examples 2 and 3, the Bola type surfactant was removed from the formulation components and replaced with an equal amount of paraffin.

[0080] The above disclosure is only the preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. An environmentally friendly paint stripper, characterized in that: The raw materials include 10-50 parts of main solvent, 5-20 parts of auxiliary solvent, 5-20 parts of surfactant, 2-15 parts of promoter, 1-5 parts of flocculant, 1-5 parts of thixotropic agent and balance water by weight, wherein the surfactant is a Bola-type fluorinated phosphate surfactant and any one or a combination of polyoxyethylene isooctyl alcohol ether monophosphate, polyoxyethylene fatty alcohol ether phosphate, alkyl phosphate, polyoxyethylene alkylphenol ether phosphate, long-chain polyoxyethylene fatty alcohol ether, polyoxyethylene alkylphenol ether and polyoxyethylene fatty acid ester.

2. An environmentally friendly paint stripper according to claim 1, characterized in that: The Bola type fluorinated phosphate surfactant is prepared by quantitatively esterifying perfluoropolyether diol with dicarboxylic acid and then reacting with a phosphating agent.

3. An environmentally friendly paint stripper according to claim 2, characterized in that: The main solvent is a high-boiling point ether substance, including any one or a combination of propylene glycol phenyl ether, propylene glycol butyl ether, propylene glycol propyl ether, dipropylene glycol butyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monomethyl ether, and tripropylene glycol n-butyl ether.

4. An environmentally friendly paint stripper according to claim 2, characterized in that: The cosolvent includes any one or a combination of ethanol, glycerol, propylene glycol, butanol, pentanol, hexanol, ethylene glycol, benzyl alcohol, acetone, dimethyl sulfoxide, and N-methylpyrrolidone.

5. An environmentally friendly paint stripper according to claim 2, characterized in that: The promoter is one or a combination of sodium hydroxide, potassium hydroxide, calcium hydroxide, and magnesium hydroxide; the flocculant is one or a combination of polyferric sulfate, polyaluminum chloride, and polyacrylamide; and the thixotropic agent is any one or a combination of modified starch, carboxymethyl cellulose, hydroxyethyl cellulose, and fumed silica.

6. An environmentally friendly paint stripper according to claim 2, characterized in that: The main solvent is 30 parts of dipropylene glycol monomethyl ether and 10 parts of propylene glycol propyl ether, the co-solvent is 20 parts of benzyl alcohol, 5 parts of dimethyl sulfoxide, 8 parts of Bola type fluorinated phosphate surfactant, 3 parts of alkylphenol polyoxyethylene ether phosphate, the accelerator is 6 parts of sodium hydroxide, the flocculant is 3 parts of polyacrylamide, and the thixotropic agent is 2 parts of fumed silica.

7. A method for preparing an environmentally friendly paint stripper, characterized in that: include: Preparation of Bola type fluorinated phosphate surfactant: Step 1: add 100 ml of dimethyl sulfoxide, 7.36 g of glutamic acid (0.05 mol), and 3 g of concentrated H2SO4 to a 500 ml three-necked flask, raise the temperature while stirring, raise the temperature to 85°C, keep the temperature stable, slowly add 100 g of perfluoropolyether diol (molecular weight 1000, 0.1 mol) through a constant pressure dropping funnel to carry out esterification reaction, and the water generated during the reaction flows into the water separator through a straight condenser tube, maintain 85°C, react for 18 hours, introduce the reaction product into a single-necked bottle, place it on a rotary evaporator to remove water, and obtain product a; Step 2: The system adopts an ice-water bath, pours the obtained product a into a 500ml three-necked flask, stirs, and when cooled to 0-5°C, slowly drops 15.33g of phosphorus oxychloride (0.1mol) through a constant pressure dropping funnel. After the addition is completed, continue the ice-water bath reaction for 5h to obtain product b. The reaction device is connected to a bend pipe and passed into a 30% sodium hydroxide aqueous solution for absorption. The reaction progress is monitored by detecting the concentration of the NaOH absorption solution; Step 3, this step of reaction is to hydrolyze the remaining -P-Cl into -P-OH, directly add 200 ml of deionized water to the reaction product b in step 2, stir and heat to 70°C, hydrolyze for 2 hours, the reaction device in this step is also connected to a bend pipe, the generated HCl gas is passed into a 30% sodium hydroxide aqueous solution for absorption, and the reaction progress is determined by detecting the concentration of the NaOH absorption liquid. When the concentration of the NaOH absorption liquid no longer changes, stop heating; use the obtained Bola type fluorinated phosphate surfactant to prepare an environmentally friendly paint stripper, the steps are: add water to the reactor, add a thixotropic agent while stirring, after the thixotropic agent is dispersed and dissolved, add the main solvent and the auxiliary solvent to the reactor in turn, stir evenly, then add the Bola type fluorinated phosphate surfactant and alkylphenol polyoxyethylene ether phosphate, stir for 15 minutes, add a promoter, wait for complete dissolution, add a flocculant and water, stir evenly, and obtain a finished paint stripper.

8. The method for preparing an environmentally friendly paint stripper according to claim 7, characterized in that: The main solvent is a high-boiling point ether substance, including any one or a combination of propylene glycol phenyl ether, propylene glycol butyl ether, propylene glycol propyl ether, dipropylene glycol butyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monomethyl ether, and tripropylene glycol n-butyl ether; the co-solvent includes any one or a combination of ethanol, glycerol, propylene glycol, butanol, pentanol, hexanol, ethylene glycol, benzyl alcohol, acetone, dimethyl sulfoxide, and N-methylpyrrolidone.

9. The method for preparing an environmentally friendly paint stripper according to claim 8, characterized in that: By weight, the main solvent comprises 10 to 50 parts, the co-solvent comprises 5 to 20 parts, the surfactant comprises 5 to 20 parts, the accelerator comprises 2 to 15 parts, the flocculant comprises 1 to 5 parts, the thixotropic agent comprises 1 to 5 parts, and the balance is water.

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