Chemical stripping solution and preparation method and application thereof

Abstract

The invention discloses a chemical stripping solution as well as a preparation method and application thereof. The chemical stripping liquid is prepared from the following components in parts by weight: 39 to 51 parts of ether-based ionic liquid, 1 to 21 parts of carboxyl ionic liquid and 39 to 51 parts of pyrrolidine ionic liquid. When the chemical deplating solution is used for deplating metal on the surface of plastic through an electrolytic method, the excellent deplating rate is achieved, and recycled plastic still has good impact resistance and low yellowing.

Description

Technical Field

[0001] The invention belongs to the technical field of waste plastic recycling, and more specifically, relates to a chemical deplating solution, a preparation method and application thereof. Background Art

[0002] The plastic electroplating process can not only give plastic parts a metallic luster and texture, but also reduce the weight of the parts and reduce costs. Therefore, the electroplating process is widely used in the automotive, electronics, bathroom, fashion and fast-moving consumer goods industries. ABS plastic has excellent electroplating properties and is widely used in electroplated parts. At present, a large number of scrapped electroplated parts are generated every year. Efficient and environmentally friendly recycling of electroplated parts is not only a reuse of resources, but also protects the environment. The metal coating on the surface of ABS electroplated parts is difficult to remove during the recycling process. The residual coating will reduce the performance of ABS. Therefore, the coating must be removed during the recycling of waste electroplated parts.

[0003] At present, there are two main methods for processing ABS electroplated parts: physical method and chemical method. The physical method is to first break the electroplated parts into smaller pieces, and then remove the coating by grinding and cleaning with equipment. This method is time-consuming, and there are many residual coatings, and the efficiency of coating removal is low. The chemical method is to immerse the electroplated parts in a chemical deplating solution and rely on chemical reactions to remove the coating. Chemical deplating solutions usually contain acidic substances, strong oxidizing substances and metal salts, which will cause environmental pollution; in addition, chemical reagents will corrode the ABS substrate, causing the mechanical properties of the ABS substrate to decrease, and will make the material prone to aging and yellowing.

[0004] Patent CN112063842A discloses a deplating and recycling process for electroplated ABS plastics, which uses HCl+H 2 O 2 The stripping solution system can complete the stripping after 4-6 hours of treatment, but it mainly focuses on the recovery of the metal coating. 2 O 2 The deplating solution system has strong oxidizing properties, which will destroy the plastic structure and reduce its performance; and the recycled plastic will age and turn yellow.

[0005] Therefore, how to provide an excellent chemical stripping solution that can maintain good performance of the recycled plastic while ensuring an excellent stripping rate has become a technical problem that needs to be solved urgently. Summary of the invention

[0006] In view of the above existing technical problems, the primary purpose of the present invention is to provide a chemical stripping solution.

[0007] The second object of the present invention is to provide a method for preparing a chemical deplating solution.

[0008] The third object of the present invention is to provide an application of a chemical stripping solution in removing metal coatings on plastic surfaces.

[0009] A fourth object of the present invention is to provide a recycled plastic.

[0010] A fifth object of the present invention is to provide a method for removing the metal coating on the surface of a plastic electroplated part.

[0011] In order to achieve the above object, the present invention is implemented by the following technical solutions:

[0012] A chemical deplating solution comprises the following components by weight: 39 to 51 parts of ether-based ionic liquid, 1 to 21 parts of carboxyl-based ionic liquid, and 39 to 51 parts of pyrrolidine-based ionic liquid.

[0013] The present invention provides a chemical deplating solution composed of ionic liquids, which includes ether-based ionic liquids, carboxyl-based ionic liquids and pyrrolidine-based ionic liquids. The inventors have found through research that ether-based ionic liquids have the characteristics of low melting point, low viscosity and high conductivity, and have excellent performance as electrolytes. Carboxyl-based ionic liquids have strong metal complexing ability and have excellent performance in dissolving metal oxides and metal compounds. Pyrrolidine-based ionic liquids have good chemical stability, which can make the electrolyte system more stable and improve the deplating rate.

[0014] The inventors found through research that the chemical deplating liquid system formed by the above three combinations has excellent electrical conductivity, can synergistically improve the electrolytic reaction efficiency in the metal deplating process, and thus improve the deplating rate. In addition, the above chemical deplating liquid not only has an excellent deplating rate when the metal on the plastic surface is electrolytically deplated, but also the recycled plastic still has good impact resistance and low yellowing. The chemical deplating liquid does not use strongly acidic and strongly oxidizing chemical reagents, and the deplating liquid can be reused, which has little pollution to the environment.

[0015] Preferably, in the chemical deplating solution, the weight percentage of the ether-based ionic liquid is not less than 35%.

[0016] In some specific embodiments, the ether-based ionic liquid is an ether-based imidazole ionic liquid; and / or

[0017] The carboxyl ionic liquid is one or more of a carboxyimidazole ionic liquid and a carboxypyrrolidine ionic liquid.

[0018] In some specific embodiments, at least one of the following (a) to (c) is selected:

[0019] (a) the cation in the ether-based ionic liquid is selected from one or more of 1-methoxyethyl-3-methylimidazole and 1-ethoxyethyl-3-methylimidazole;

[0020] (b) the cation in the carboxyl ionic liquid is selected from one or more of 1-carboxymethyl-3-methylimidazole, 1-carboxyethyl-3-methylimidazole, and N-carboxymethyl-N-methylpyrrolidine;

[0021] (c) The cation in the pyrrolidine ionic liquid is selected from one or more of N-ethyl-N-methylpyrrolidine, N-propyl-N-methylpyrrolidine, and N-butyl-N-methylpyrrolidine.

[0022] In some specific embodiments, at least one of the following (d) to (f) is selected:

[0023] (d) the anion in the ether-based ionic liquid is selected from one or more of tetrafluoroboric acid, bromine, bis(fluorosulfonyl)imide, and hexafluorophosphoric acid;

[0024] (e) the anion in the carboxyl ionic liquid is one or more of chloride, nitric acid, and trifluoromethanesulfonic acid;

[0025] (f) The anion in the pyrrolidine ionic liquid is one or more of acetic acid, iodine, hexafluorophosphate, and bis(fluorosulfonyl)imide.

[0026] In some specific embodiments, the ether-based ionic liquid is selected from one or more of 1-methoxyethyl-3-methylimidazolium tetrafluoroborate, 1-methoxyethyl-3-methylimidazolium bromide, 1-ethoxyethyl-3-methylimidazolium hexafluorophosphate, and 1-ethoxyethyl-3-methylimidazolium bisfluorosulfonyl imide.

[0027] In some specific embodiments, the carboxyl ionic liquid is selected from one or more of 1-carboxymethyl-3-methylimidazolium chloride, 1-carboxyethyl-3-methylimidazolium nitrate, N-carboxymethyl-N-methylpyrrolidine chloride, and 1-carboxyethyl-3-methylimidazolium trifluoromethanesulfonate.

[0028] In some specific embodiments, the pyrrolidine ionic liquid is selected from one or more of N-ethyl-N-methylpyrrolidine acetate, N-propyl-N-methylpyrrolidine iodide, N-butyl-N-methylpyrrolidine hexafluorophosphate, and N-butyl-N-methylpyrrolidine bisfluorosulfonimide.

[0029] In some specific embodiments, the ether-based ionic liquid in the chemical deplating solution can be 41 parts, 43 parts, 45 parts, 47 parts, 49 parts, etc., or an interval range formed by any of the above values, such as 41-47 parts, 43-49 parts, etc., by weight, and the present invention is not limited thereto; the pyrrolidine-based ionic liquid can be 41 parts, 43 parts, 45 parts, 47 parts, 49 parts, etc., or an interval range formed by any of the above values, such as 41-47 parts, 43-49 parts, etc., and the present invention is not limited thereto; the carboxyl-based ionic liquid can be 3 parts, 5 parts, 7 parts, 9 parts, 11 parts, 13 parts, 15 parts, 17 parts, 19 parts, etc., or an interval range formed by any of the above values, such as 5-13 parts, 7-19 parts, etc., and the present invention is not limited thereto.

[0030] Preferably, the chemical deplating solution comprises the following components in parts by weight: 43 to 48 parts of ether-based ionic liquid, 5 to 15 parts of carboxyl-based ionic liquid, and 42 to 47 parts of pyrrolidine-based ionic liquid.

[0031] Furthermore, the present invention seeks to protect a method for preparing a chemical stripping solution, comprising the following preparation steps: uniformly mixing an ether-based ionic liquid, a carboxyl-based ionic liquid and a pyrrolidine-based ionic liquid to obtain the chemical plating solution.

[0032] Furthermore, the present invention seeks to protect the use of a chemical stripping solution in removing metal coatings from plastic surfaces.

[0033] In some specific embodiments, the plastic is selected from one or more of ABS, PP, PA, and PC.

[0034] In some specific embodiments, the average particle size of the plastic is ≤30 mm. More specifically, the average particle size of the plastic is 15 to 20 mm. If the average particle size of the plastic is too large, the specific surface area is small and the stripping efficiency is low; if the average particle size is too small, the material loss during the treatment process is large and the yield is low.

[0035] In some specific embodiments, the metal coating on the plastic surface may be a metal plating commonly used on plastic surfaces in the art; further, the metal in the metal coating may be one or more of chromium, nickel, and copper.

[0036] Furthermore, the present invention seeks to protect a recycled plastic, which is obtained by electrolyzing a plastic having a metal coating on its surface using the above-mentioned chemical deplating solution.

[0037] Furthermore, the present invention seeks to protect a method for removing a metal coating on a plastic surface, wherein the chemical deplating solution is used to electrolyze a plastic coated with a metal coating to remove the metal coating on the plastic surface.

[0038] In some specific embodiments, the anode and cathode used in the electrolysis reaction are graphite.

[0039] In some specific embodiments, the voltage of the electrolysis reaction is 1-50V.

[0040] Furthermore, the plastic electroplated with the metal coating is pre-treated before the electrolytic reaction, and the pre-treatment includes one or more of crushing, cleaning, rinsing and dehydration.

[0041] In some specific embodiments, the cleaning treatment can use a cleaning agent conventionally used in the art for cleaning plastic electroplated parts, and the cleaning treatment can remove the tiny plastic powder, dust, oil stains and other dirty components in the plastic electroplated parts. More specifically, the cleaning agent can be an ester surfactant and / or an alcohol ether surfactant. Ester surfactants include but are not limited to polysorbate, lauryl alcohol ether sulfate, etc.; alcohol ether surfactants include but are not limited to isomeric C13 alcohol polyoxyethylene ethers, linear fatty alcohol polyoxyethylene ethers, C12-14 secondary alcohol polyoxyethylene ethers, octoxynol, etc. The concentration of the cleaning agent can be the concentration conventionally used in the art for cleaning plastic electroplated parts. More specifically, the concentration of the cleaning agent can be 0.01-1%.

[0042] In some specific embodiments, the rinsing treatment is to rinse the cleaned flakes in clean water to remove impurities remaining on the surface of the flakes.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] The present invention provides a chemical deplating solution, which has excellent electrical conductivity and can synergistically improve the electrolytic reaction efficiency in the metal deplating process, thereby improving the deplating rate. In addition, when the chemical deplating solution is used to electrolytically deplating the metal on the surface of the plastic, it not only has an excellent deplating rate, but also the recycled plastic still has good impact resistance and low yellowing. DETAILED DESCRIPTION

[0045] The present invention is further described below in conjunction with the specification and specific examples, but the examples do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0046] The raw materials of the embodiments and comparative examples are as follows:

[0047] Plastic electroplating parts, plastic ABS, metal plating is copper, nickel, chromium, Hunan Xinjiyuan New Material Technology Co., Ltd.

[0048] Ether-based ionic liquid 1,1-ethoxyethyl-3-methylimidazolium hexafluorophosphate, Mooney Chemical Technology (Shanghai) Co., Ltd.

[0049] Ether-based ionic liquid 2,1-methoxyethyl-3-methylimidazolium tetrafluoroborate, Mooney Chemical Technology (Shanghai) Co., Ltd.

[0050] Carboxyl ionic liquid 1,1-carboxyethyl-3-methylimidazolium nitrate, Mooney Chemical Technology (Shanghai) Co., Ltd.

[0051] Carboxyl ionic liquid 2,1-carboxyethyl-3-methylimidazolium trifluoromethanesulfonate, Mooney Chemical Technology (Shanghai) Co., Ltd.

[0052] Pyrrolidine ionic liquid 1, N-ethyl-N-methylpyrrolidine acetate, Mooney Chemical Technology (Shanghai) Co., Ltd.

[0053] Pyrrolidine ionic liquid 2, N-butyl-N-methylpyrrolidine bis(fluorosulfonyl)imide salt, Mooney Chemical Technology (Shanghai) Co., Ltd.

[0054] Disubstituted imidazole ionic liquid, 1,3-dimethylimidazolium tetrafluoroborate, Mooney Chemical Technology (Shanghai) Co., Ltd.

[0055] Surfactant, octoxynol, OP-10, commercially available.

[0056] Unless otherwise specified, the components (surfactants) used in the parallel examples and comparative examples are all the same commercially available products.

[0057] Example 1

[0058] The ether-based ionic liquid, carboxyl-based ionic liquid and pyrrolidine-based ionic liquid were poured into a stirring kettle and stirred to mix evenly. The stirring speed of the stirring paddle was 80 rpm and the stirring time was 20 min to obtain a chemical deplating solution.

[0059] Embodiment 2 to Embodiment 8

[0060] The weight parts of the raw materials used in the following examples are shown in Table 1.

[0061] The specific preparation steps of the following examples are the same as those of Example 1.

[0062] Table 1

[0063]

[0064]

[0065] Example 9

[0066] (1) Pretreatment: crush the plastic electroplating parts into flakes with an average particle size of 20 mm; wash the flakes with a cleaning agent to remove tiny plastic powders, dust, oil stains and other dirty components in the material, rinse and dehydrate after washing to obtain the pretreated plastic electroplating parts;

[0067] (2) The plastic plated parts are placed in an electrolytic cell, the chemical deplating solution prepared in Example 1 is added to the electrolytic cell as an electrolyte, a pair of graphite plates are placed in the electrolytic cell as an anode and a cathode, the electrodes are connected to a DC power supply with a voltage of 5 V, an electrolytic reaction is carried out, and the processing time is 10 minutes to remove the metal coating on the surface of the plastic plated parts.

[0068] Embodiment 10 to Embodiment 16

[0069] The difference between Example 10 to Example 16 and Example 9 is that the chemical stripping solutions prepared in Example 2 to Example 8 are respectively used as electrolytes.

[0070] Comparative Example 1 to Comparative Example 10

[0071] In each comparative example, the weight parts of the raw materials used in the chemical stripping solution are shown in Table 2.

[0072] In each comparative example, the specific preparation steps of the chemical stripping solution are the same as those in Example 1.

[0073] Comparative Example 9 adopts a chemical stripping method, and the specific operation is: the plastic electroplated part obtained after the pretreatment in step (1) of Example 1 is placed in a stripping solution and soaked for 10 minutes. The stripping solution composition is as follows: 20% HCl, 2% H 2 O 2 , 78% deionized water.

[0074] Comparative Example 10 adopts an electrolytic stripping method. The difference between Comparative Example 10 and Example 9 is that the stripping solution is a 20% NaCl aqueous solution.

[0075] Other comparative examples are as shown in Example 9 for the treatment of plastic electroplated parts.

[0076] Table 2 shows the formula components of each comparative example:

[0077] Table 2

[0078]

[0079]

[0080] The recycled plastics treated in the above examples and comparative examples were tested using the following method.

[0081] (1) Izod notched impact strength: Tested in accordance with GB / T 1843-2008, A-type notch, notch size 2 mm. Five samples were tested in each group, and the average value was taken.

[0082] (2) Yellowing (Δb): The material is injection molded into a color plate, and the color Lab value of the color plate is measured using a colorimeter. The unbaked color b value is b 0 Then place the color plate in an oven at 80℃ for 2h and measure the color b value after baking. 1 , then the color b value change (Δb) calculation formula is as follows:

[0083] Δb=b 1 -b 0

[0084] (3) Stripping rate: Weigh the mass of the plastic electroplated part as m 0 After electrolytic stripping for 10 minutes, the sample was dried and weighed to obtain a mass of m 1 After the electrolytic stripping was completed, the sample was subjected to chemical stripping for 2 h (the deplating solution composition was 20% HCl, 10% H 2 O 2 , 70% deionized water), ensure that the coating is completely removed, and weigh the mass m after cleaning and drying. 2 , then the stripping rate (r) is calculated as follows:

[0085] r=(m 0 -m 1 ) / (m 0 -m 2 )×100%

[0086] Table 3 and Table 4 are the performance test results of each embodiment and comparative example respectively.

[0087] Table 3

[0088]

[0089] Table 4

[0090]

[0091] From the above-mentioned data, it can be seen that the chemical deplating solution provided by the present invention has excellent electrolytic reaction efficiency for the metal coating on the plastic surface. While improving the deplating rate, the recycled plastic still has good impact resistance and low yellowing degree. The notched impact strength of the plastic recycled by electroplating with the chemical deplating solution provided by the present invention is ≥19.1 kJ / m 2 , Δb≤0.61, stripping rate≥97.5%; further preferably, the notched impact strength of the plastic recovered by electroplating with the chemical stripping solution provided by the present invention is ≥21.3 kJ / m2 , Δb≤0.60, stripping rate ≥98.1%.

[0092] It can be seen from Comparative Examples 1 to 4 that when ether-based ionic liquids, pyrrolidine-based ionic liquids, carboxyl-based ionic liquids, and disubstituted imidazole-based ionic liquids are used alone as chemical stripping solutions, it is difficult to achieve the technical effects of the present invention.

[0093] It can be seen from Example 1, Comparative Example 5 and Comparative Example 6 that when the ether-based ionic liquid, the pyrrolidine-based ionic liquid and the carboxyl-based ionic liquid are used in combination, the notched impact strength of the plastic is synergistically improved.

[0094] It can be seen from Example 1 and Comparative Example 7 that when the imidazole ionic liquid containing an ether group or a carboxyl group is combined with the pyrrolidine ionic liquid, the recycled plastic has better notched impact strength.

[0095] It can be seen from Example 1 and Comparative Example 9 that the chemical deplating solution provided by the present invention can reduce the yellowing of the recycled plastic compared to the deplating solution composed of hydrochloric acid + hydrogen peroxide.

[0096] It can be seen from Example 1 and Comparative Example 10 that the chemical deplating solution provided by the present invention can significantly improve the notched impact strength and deplating rate of the recycled plastic compared to the deplating using sodium chloride ionic liquid.

[0097] The foregoing examples are merely illustrative and are used to explain some features of the method of the present invention. The appended claims are intended to require the widest possible range that can be imagined, and the embodiments presented herein are demonstrated by the applicant's actual test results. Therefore, the applicant's intention is that the appended claims are not limited by the selection of examples that illustrate the features of the present invention. Some numerical ranges used in the claims also include sub-ranges therein, and changes in these ranges should also be interpreted as being covered by the appended claims where possible.

Claims

1. A chemical stripping solution, characterized in that: The composition comprises the following components by weight: 39 to 51 parts of ether-based ionic liquid, 1 to 21 parts of carboxyl-based ionic liquid and 39 to 51 parts of pyrrolidine-based ionic liquid.

2. The chemical deplating solution according to claim 1, characterized in that: The ether-based ionic liquid is an ether-based imidazole ionic liquid; and / or The carboxyl ionic liquid is one or more of a carboxyimidazole ionic liquid and a carboxypyrrolidine ionic liquid.

3. The chemical deplating solution according to claim 1, characterized in that: At least one selected from the following (a) to (c): (a) the cation in the ether-based ionic liquid is selected from one or more of 1-methoxyethyl-3-methylimidazole and 1-ethoxyethyl-3-methylimidazole; (b) the cation in the carboxyl ionic liquid is selected from one or more of 1-carboxymethyl-3-methylimidazole, 1-carboxyethyl-3-methylimidazole, and N-carboxymethyl-N-methylpyrrolidine; (c) The cation in the pyrrolidine ionic liquid is selected from one or more of N-ethyl-N-methylpyrrolidine, N-propyl-N-methylpyrrolidine, and N-butyl-N-methylpyrrolidine.

4. The chemical deplating solution according to claim 1 or 3, characterized in that: At least one selected from the following (d) to (f): (d) the anion in the ether-based ionic liquid is selected from one or more of tetrafluoroboric acid, bromine, bis(fluorosulfonyl)imide, and hexafluorophosphoric acid; (e) the anion in the carboxyl ionic liquid is one or more of chloride, nitric acid, and trifluoromethanesulfonic acid; (f) The anion in the pyrrolidine ionic liquid is one or more of acetic acid, iodine, hexafluorophosphate, and bis(fluorosulfonyl)imide.

5. The chemical deplating solution according to claim 1, characterized in that: The chemical deplating solution comprises the following components by weight: 43 to 48 parts of ether-based ionic liquid, 5 to 15 parts of carboxyl-based ionic liquid, and 42 to 47 parts of pyrrolidine-based ionic liquid.

6. The method for preparing the chemical deplating solution according to any one of claims 1 to 5, characterized in that: The chemical deplating solution is obtained by uniformly mixing the ether-based ionic liquid, the carboxyl-based ionic liquid and the pyrrolidine-based ionic liquid.

7. Use of the chemical stripping solution according to any one of claims 1 to 5 in removing metal coatings on plastic surfaces.

8. The use according to claim 7, characterized in that: The plastic is selected from one or more of ABS, PP, PA and PC.

9. A recycled plastic, characterized in that: The plastic is prepared by electrolyzing a plastic having a metal coating on its surface with the chemical deplating solution described in any one of claims 1 to 5.

10. A method for removing metal coating on plastic surface, characterized in that: The chemical deplating solution according to any one of claims 1 to 5 is used to electrolyze the plastic coated with a metal coating to remove the metal coating on the surface of the plastic.

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