PEI car lamp recycling stripping solution and recycling method

Abstract

The application relates to the technical field of recycling treatment, and discloses a PEI car lamp recycling stripping solution and a recycling method, wherein the stripping solution comprises the following raw materials according to mass parts: water 100 parts; soluble copper salt 0.1-30 parts; potassium hydrogen phthalate 0.01-10 parts; complexing agent 0.01-5 parts; and surfactant 0.01-1 part. The PEI car lamp recycling method is to clean the waste PEI car lamp, then perform ultrasonic treatment in the stripping solution, take out, clean, melt and blend to obtain PEI recycling material. The stripping solution of the application is almost neutral, does not corrode the equipment, does not produce hydrogen emission in the stripping process, does not cause hydrolysis or other influences on the PEI molecules, and the mechanical properties of the PEI recycling material are kept good.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of recycling, in particular to a PEI car lamp recycling stripping solution and a recycling method. BACKGROUND

[0002] PEI (polyetherimide) is used to make the reflector bowl of the high-end car's headlamp and fog lamp due to its good heat resistance and mechanical properties. A large number of cars are scrapped every year, and the car lamps matched with the cars are also discarded in large quantities. At present, the number of car lamps in a medium and high-end car on the market is about 30 or so, so the car lamp market capacity is huge. In the huge car lamp recycling market, there is an urgent need for the recycling of car lamp PEI.

[0003] Since PEI is colorless and transparent, a layer of metal about 10 microns thick needs to be plated on its surface when used for light reflection. The metal is mostly aluminum. After the car is scrapped, the aluminum-plated PEI is difficult to be directly recycled and utilized, and the aluminum on the surface needs to be stripped off first, and then the PEI is physically recycled. However, there is no mature process for batch recycling of car lamp PEI at present. Therefore, it is of great significance to design and develop a process flow that can batch process and recycle car lamp PEI, prepare high-performance regenerated PEI, and realize the green recycling of PEI for the sustainable green and environmental protection development of the automobile industry.

[0004] Aluminum has good reactivity with strong acids and strong bases, so by treating with strong acid or strong base, the metal aluminum on the surface of PEI can be effectively removed. For the stripping of the metal aluminum coating on the surface of the object, the existing technology also has a method of using strong acid or strong base to dissolve the metal aluminum to remove the coating.

[0005] Chinese patent CN101880882A discloses a stripping solution for sintered Nd-Fe-B surface aluminum plating layer. The stripping solution uses sodium hydroxide as a corrosion agent, sodium carbonate as an auxiliary salt, and also includes a complexing agent that can promote the dissolution of metal aluminum, a corrosion inhibitor that can slow down the corrosion of the substrate, and a surfactant that can uniformly dissolve the aluminum plating layer. The stripping solution provided by the invention can quickly and uniformly strip the sintered Nd-Fe-B surface aluminum plating layer, while reducing the damage to the sintered Nd-Fe-B substrate. However, the stripping solution provided by the invention is strongly alkaline, which may pose a potential risk to the overall performance of PEI.

[0006] Chinese patent CN113249727A provides a stripping solution, a stripping method and application thereof. The composition of the stripping solution includes the following components: hydrochloric acid, sulfuric acid, complexing agent, corrosion inhibitor, surfactant and water. The stripping solution of the invention is used to successfully strip the aluminum-tin film layer on the surface of the steel-backed copper-based composite bearing. However, the hydrochloric acid and sulfuric acid used in the invention are strong acids, and the concentration is as high as 100-200 g / L, which requires a very high concentration of acid and has strong corrosive properties to the equipment.

[0007] Chinese patent CN113930768A discloses a neodymium-iron-boron magnet surface multiple coating layer stripping solution and stripping method and application thereof. The stripping solution comprises: a solvent selected from water and a water-miscible organic solvent; a solute, the solute comprising the following components: alkali 10-30 g / L, complexing agent 2-6 g / L, corrosion inhibitor 1-10 g / L. The invention also provides a stripping method, by vibration stripping, after adding a small amount of the above stripping solution, the stripping of the surface of the workpiece can be completed in a low-alkaline concentration state at room temperature. The coating that can be treated by the invention can include aluminum plating layer, zinc plating layer, epoxy layer, phenolic resin layer or aluminum-zinc-tin composite layer. However, the invention uses strong alkali as the main component, which is not conducive to the stripping of PEI type polymers sensitive to alkali, and hydrogen gas is released during the stripping process, which is not conducive to safe operation.

[0008] Metallic aluminum is an amphoteric metal, that is, it can react with both acids and bases. Therefore, in the prior art, strong acids or strong bases are often used to strip aluminum metal coatings. When metallic aluminum is placed in a strong acid or a strong base, it will rapidly react with the strong acid or the strong base, releasing heat, and also releasing hydrogen gas. If the reaction is too violent, the number of gas bubbles will increase rapidly, and it may even cause the stripping solution to splash, affecting the safety of the operation. Moreover, if the large amount of hydrogen gas released is not collected and treated, it will bring the risk of fire and even explosion when it is freely discharged into the air, seriously affecting the safety of on-site production.

[0009] In addition, strong acids or strong bases are corrosive and can severely corrode equipment, leading to a decrease in the service life of the equipment, and even causing serious damage to the plastic itself. In particular, the damage to PEI molecules by an alkaline stripping solution is very obvious. This is because the PEI molecule structure contains a large number of imide groups, which are very sensitive to water under high temperature conditions, and will rapidly ring-open hydrolysis in the presence of a strong base.

[0010] As can be seen from the above, most of the existing metallic aluminum stripping solutions are strong alkaline or strong acid stripping solutions, neither of which is suitable for stripping PEI car lights. On the one hand, they can cause damage to the equipment, and on the other hand, they can cause hydrolysis of the PEI molecular weight, seriously affecting the comprehensive performance of the regenerated PEI. It is worth noting that the PEI molecular chain is particularly sensitive to alkali, and long-term immersion in a strong alkaline stripping solution can cause irreversible damage to the performance of PEI. In addition, when aluminum reacts with strong acid or alkali, a large amount of hydrogen gas is rapidly released, which not only causes bubbles in the stripping solution, leading to fluctuations in the stripping solution, but also is released into the atmosphere, which can cause a fire or even an explosion if the concentration accumulates to a certain level. Therefore, it is of great significance to invent a new PEI stripping and physical recycling process for car lights for the high-quality recycling of PEI. SUMMARY

[0011] The present application provides an acid-alkali neutral stripping solution, which is mild and does not corrode the equipment, and the gas release speed is mild during the stripping process, and the PEI molecules are not hydrolyzed or affected, and the mechanical properties of the PEI recovered material are good.

[0012] To achieve the above object, the technical scheme adopted by the present application is:

[0013] A PEI car lamp recovery stripping solution, characterized in that the raw materials include:

[0014] water 100 parts by mass;

[0015] soluble copper salt 0.1-30 parts by mass;

[0016] potassium hydrogen phthalate 0.01-10 parts by mass;

[0017] complexing agent 0.01-5 parts by mass;

[0018] surfactant 0.01-1 parts by mass;

[0019] The present application designs a weak acid stripping solution, which is mainly copper salt solution and supplemented with potassium hydrogen phthalate, and chemically reacts with aluminum to achieve the purpose of stripping aluminum. The surface of the metal aluminum is easily passivated and forms a dense aluminum oxide film. Aluminum oxide cannot chemically react with copper salt, so when aluminum is placed in a copper sulfate solution, it is usually difficult to quickly react. Even if the aluminum is placed in the solution for more than one day, no obvious chemical reaction occurs. Therefore, how to overcome the passivation of the surface of the metal aluminum and make the copper salt quickly chemically react with the metal is one of the core technical problems to be solved by the present application. The applicant accidentally found that when the metal aluminum is immersed in the copper salt solution, a certain amount of potassium hydrogen phthalate, complexing agent, and surfactant are added as auxiliary, and heating and ultrasonic treatment process are supplemented, the stripping of the aluminum coating can be accelerated, and the PEI molecules are not damaged.

[0020] Preferably, the stripping solution includes raw materials in the following mass fractions:

[0021] water 100 parts by mass;

[0022] soluble copper salt 10-30 parts by mass;

[0023] potassium hydrogen phthalate 0.01-5 parts by mass;

[0024] complexing agent 0.01-5 parts by mass;

[0025] surfactant 0.01-1 parts by mass.

[0026] The soluble copper salt includes one or more of copper sulfate, copper chloride, copper nitrate. It can be further preferred to be copper sulfate or copper chloride.

[0027] Preferably, the amount of potassium hydrogen phthalate is 0.1-5 parts.

[0028] The complexing agent includes one or more of tetrasodium ethylenediaminetetraacetate tetrahydrate, sodium tripolyphosphate, potassium sodium tartrate, sodium citrate, sodium gluconate. The complexing agent can be combined with Al 3 +,Cu 2 + plasma to accelerate the stripping of the Al coating.

[0029] The surfactant includes one or more of sodium dodecyl benzene sulfonate, polyethylene glycol, glycerol. The surfactant can effectively remove the oil stains on the surface of the Al coating, so that the coating surface is more easily infiltrated by the stripping solution, and the stripping efficiency is improved.

[0030] The application also provides a PET car lamp recycling method, comprising the steps of:

[0031] Step 1, preparing the stripping solution;

[0032] Step 2, placing the sorted and washed waste PEI car lamp in the stripping solution, and ultrasonic treatment to obtain a stripped PEI car lamp, and then washing, crushing and drying the stripped PEI car lamp to obtain PEI crushed material;

[0033] Step 3, melting and granulating the PEI crushed material to obtain recycled PEI granules.

[0034] Preferably, the washing is water washing to remove simple impurities and dust.

[0035] The ultrasonic treatment is at 40-90℃ for 1-10h; the ultrasonic treatment can accelerate the stripping of the coating surface stains, and when the stripping solution begins to corrode the Al coating, the ultrasonic treatment can also accelerate the mechanical stripping of the coating, further improving the stripping effect. Appropriately increasing the temperature can not only accelerate the thermal motion of the stripping solution molecules, but also increase the solubility of potassium hydrogen phthalate, thereby increasing the concentration of potassium hydrogen phthalate and reducing the PH value of the stripping solution, and accelerating the corrosion speed of the Al coating.

[0036] Preferably, the ultrasonic treatment is at 40-70℃ for 1-3h.

[0037] Preferably, the stripped PEI car lamp is rubbed and cleaned with water after crushing, and then dried;

[0038] Preferably, the temperature for melting and granulating in step 3 is 250-360℃.

[0039] Further, the double screw extruder is used for melt granulation, the temperature of the conveying section of the double screw extruder is controlled to be 100-150 DEG C, the temperature of the plasticizing section is controlled to be 250-300 DEG C, the temperature of the natural exhaust section is controlled to be 300-350 DEG C, the temperature of the mixing section is controlled to be 320-360 DEG C, the temperature of the vacuum exhaust section and the homogenizing (metering) section is controlled to be 320-350 DEG C, and the temperature of the die head is 320-330 DEG C.

[0040] The impact strength of the PEI recycled material obtained by the present application is maintained at 5KJ / m 2 The tensile strength is higher than 100MPa, the bending strength is higher than 150MPa, the bending modulus is higher than 3.0GPa, and the comprehensive mechanical properties are excellent.

[0041] Compared with the prior art, the present application has the following beneficial effects:

[0042] (1) The PEI car lamp recycling stripping solution provided by the present application is weakly acidic, avoiding the corrosion of strong acid or strong base to the equipment, and when the aluminum is stripped, no large amount of gas is generated, the liquid level of the stripping solution is not fluctuated, the stripping solution is not splashed, and the risk of combustion or explosion is not brought to the surrounding environment of the equipment, so that the safety is higher, and the performance of the PEI resin is not affected.

[0043] (2) The PEI car lamp recycling method provided by the present application can effectively remove the surface coating aluminum, realize the high-value recycling of the car lamp PEI, and the prepared PEI recycled material has excellent mechanical properties. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 The morphological diagrams before and after stripping of the recycled car lamp in Example 1. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below with examples. It should be understood that the specific examples described herein are only used to explain the present application, and are not used to limit the present application. Those skilled in the art can modify or replace the equivalent without departing from the spirit and scope of the present application, which should be covered within the protection scope of the present application.

[0046] The raw materials used in the following specific embodiments are all purchased from the market.

[0047] The physical properties of the recycled PEI material are tested according to ISO standards, the IZOD notch impact strength is tested by 180, the tensile strength and elongation at break are tested by ISO527, the bending strength and bending modulus are tested by ISO178, and the haze of the PEI plate (3mm transmission) is tested by ISO13468.

[0048] Example 1

[0049] Step 1, according to water 100 parts, copper sulfate 20 parts, potassium hydrogen phthalate 1 part, sodium citrate 3 parts, sodium dodecyl benzene sulfonate 0.05 parts of the preparation of stripping solution.

[0050] Step 2, the artificial sorting, disassembling, simple water impact of waste PEI car lights into the stripping solution, heated to 50℃, ultrasonic treatment for 2 hours, the naked eye observation of stripping complete, stop stripping, get stripping of PEI car lights.

[0051] Step 3, the stripping of PEI car lights with water washing, and then put into the crusher for crushing, then use water friction cleaning, spin dry after PEI broken material.

[0052] Step 4, the PEI broken material into the twin screw melt extruder for melt granulation. Twin screw extruder conveying section temperature control is 300℃, plasticizing section temperature control is 340℃, natural exhaust section temperature control is 360℃, mixing section temperature control is 350℃, vacuum exhaust section and homogenization (metering) section temperature control is 350℃, the temperature of the die is 350℃, finally get the recycled PEI material. The appearance before and after stripping as Figure 1 shown, the surface of the aluminum layer of waste PEI car lights is completely removed.

[0053] Example 2

[0054] Step 1, according to water 100 parts, copper sulfate 20 parts, potassium hydrogen phthalate 1 part, sodium citrate 3 parts, sodium dodecyl benzene sulfonate 0.05 parts of the preparation of stripping solution.

[0055] Step 2, the artificial sorting, disassembling, simple water impact of waste PEI car lights into the stripping solution, heated to 60℃, ultrasonic treatment for 1 hours, the naked eye observation of stripping complete, stop stripping, get stripping of PEI car lights.

[0056] Step 3, the stripping of PEI car lights with water washing, and then put into the crusher for crushing, then use water friction cleaning, spin dry after PEI broken material.

[0057] Step 4, the PEI broken material is added into a twin-screw melt extruder for melt granulation. The temperature of the conveying section of the twin-screw extruder is controlled at 300°C (in the actual process, whether it is also a variable value, the temperature can be controlled within a certain range), the temperature of the plasticizing section is controlled at 340°C, the temperature of the natural exhaust section is controlled at 360°C, the temperature of the mixing section is controlled at 350°C, the temperature of the vacuum exhaust section and the homogenizing (metering) section are both controlled at 350°C, and the temperature of the die head is 350°C. Finally, the recycled PEI material is obtained.

[0058] Example 3

[0059] Step 1, according to water 100 parts, copper chloride 10 parts, potassium hydrogen phthalate 5 parts, sodium citrate 0.5 parts, sodium dodecyl benzene sulfonate 0.01 parts to prepare the stripping solution.

[0060] Step 2, the waste PEI car lamp which has been manually sorted, disassembled and simply impacted by water is put into the stripping solution, heated to 60°C, and ultrasonically treated for 2 hours. After observing the completion of stripping with naked eyes, the stripping is stopped, and the stripped PEI car lamp is obtained.

[0061] Step 3, the stripped PEI car lamp is washed with clean water, then put into a crusher for crushing, and then washed by rubbing with clean water and dried to obtain the PEI broken material.

[0062] Step 4, the pretreated PEI broken material is added into a twin-screw melt extruder for melt granulation. The temperature of the conveying section of the twin-screw extruder is controlled at 300°C, the temperature of the plasticizing section is controlled at 340°C, the temperature of the natural exhaust section is controlled at 360°C, the temperature of the mixing section is controlled at 350°C, the temperature of the vacuum exhaust section and the homogenizing (metering) section are both controlled at 350°C, and the temperature of the die head is 350°C. Finally, the recycled PEI material is obtained.

[0063] Example 4

[0064] Step 1, according to water 100 parts, copper sulfate 30 parts, potassium hydrogen phthalate 0.5 parts, sodium citrate 5 parts, and sodium dodecyl benzene sulfonate 1 part to prepare the stripping solution.

[0065] Step 2, the waste PEI car lamp which has been manually sorted, disassembled and simply impacted by water is put into the stripping solution, heated to 50°C, and ultrasonically treated for 1 hour. After observing the completion of stripping with naked eyes, the stripping is stopped, and the stripped PEI car lamp is obtained.

[0066] Step 3, the stripped PEI car lamp is washed with clean water, then put into a crusher for crushing, and then washed by rubbing with clean water and dried to obtain the PEI broken material.

[0067] Step 4, the pretreated PEI broken material is added into a twin-screw melt extruder for melt granulation. The temperature of the conveying section of the twin-screw extruder is controlled at 300°C, the temperature of the plasticizing section is controlled at 340°C, the temperature of the natural exhaust section is controlled at 360°C, the temperature of the mixing section is controlled at 350°C, the temperature of the vacuum exhaust section and the homogenizing (metering) section are both controlled at 350°C, and the temperature of the die head is 350°C. Finally, the regenerated PEI material is obtained.

[0068] Comparative Example 1 without potassium hydrogen phthalate

[0069] Step 1, a stripping solution is prepared according to water 100 parts, copper chloride 10 parts, sodium citrate 0.5 parts, and sodium dodecyl benzene sulfonate 0.01 parts.

[0070] Step 2, the waste PEI car lamp that has been manually sorted, disassembled, and simply impacted by water is put into the stripping solution, heated to 80°C, and ultrasonically treated for 4 hours to obtain the stripped PEI car lamp.

[0071] Step 3, the stripped PEI car lamp is washed with clean water, then put into a crusher for crushing, and then washed by rubbing with clean water and dried to obtain the washed PEI broken material.

[0072] Step 4, the pretreated PEI broken material is added into a twin-screw melt extruder for melt granulation. The temperature of the conveying section of the twin-screw extruder is controlled at 300°C, the temperature of the plasticizing section is controlled at 340°C, the temperature of the natural exhaust section is controlled at 360°C, the temperature of the mixing section is controlled at 350°C, the temperature of the vacuum exhaust section and the homogenizing (metering) section are both controlled at 350°C, and the temperature of the die head is 350°C. Finally, the regenerated PEI material is obtained.

[0073] Comparative Example 2 without complexing agent and surfactant

[0074] Step 1, a stripping solution is prepared according to water 100 parts, copper sulfate 30 parts, and potassium hydrogen phthalate 0.5 parts.

[0075] Step 2, the waste PEI car lamp that has been manually sorted, disassembled, and simply impacted by water is put into the stripping solution, heated to 80°C, and ultrasonically treated for 3 hours. After the stripping is observed to be completed by naked eye, the stripping is stopped, and the stripped PEI car lamp is obtained.

[0076] Step 3, the stripped PEI car lamp is washed with clean water, then put into a crusher for crushing, and then washed by rubbing with clean water and dried to obtain the washed PEI broken material.

[0077] Step 4: The pretreated PEI scrap was fed into a twin-screw melt extruder for melt granulation. The temperature of the conveying section of the twin-screw extruder was controlled at 300℃, the temperature of the plasticizing section was controlled at 340℃, the temperature of the natural exhaust section was controlled at 360℃, the temperature of the mixing section was controlled at 350℃, the temperature of the vacuum exhaust section and the homogenizing (metering) section were both controlled at 350℃, and the temperature of the die was 350℃. Finally, the regenerated PEI material was obtained.

[0078] Comparative Example 3 without ultrasound without heating

[0079] The waste PEI car lamp that was manually sorted, disassembled, and simply washed with water was put into the stripping solution prepared in Step 1 of Example 1, and stirred at room temperature for 1 hour. The surface coating of the car lamp did not change significantly.

[0080] Performance test of the product

[0081] The regenerated PEI material obtained in the examples and comparative examples provided by the present application had typical properties as shown in Table 1.

[0082] Table 1: Properties of the recycled PEI material

[0083]

[0084]

[0085] The data of Examples 1-4 showed that the formulation design of the stripping solution would affect the stripping time and efficiency during the stripping of the PEI car lamp. Increasing the concentration of copper salt and potassium hydrogen phthalate could appropriately reduce the stripping temperature and reduce the stripping time, thereby improving the production efficiency.

[0086] Comparative Example 1 showed that if no potassium hydrogen phthalate was added to the stripping solution, the stripping temperature needed to be increased to 80 degrees, and the stripping time needed to be increased to 4 hours, which severely reduced the efficiency. Moreover, since the Al coating was not completely stripped, the haze of the finished particles was significantly increased. Comparative Example 2 showed that if no complexing agent and surfactant were added to the stripping solution, the desired effect could not be achieved.

Claims

1. A PEI automotive lamp recycling method, characterized by, The method comprises the steps of: Step 1, preparing a stripping solution; Step 2, placing the sorted and rinsed waste PEI car lamp into the stripping solution and performing ultrasonic treatment to obtain a stripped PEI car lamp, and then rinsing, crushing and drying the stripped PEI car lamp to obtain PEI crushed material; Step 3, melting and granulating the PEI crushed material to obtain recycled PEI granules; The stripping solution comprises raw materials in parts by mass: water 100 parts; soluble copper salt 0.1-30 parts; potassium hydrogen phthalate 0.01-10 parts; complexing agent 0.01-5 parts; surfactant 0.01-1 part.

2. The PEI automotive lamp recycling method of claim 1, wherein, The stripping solution comprises raw materials in parts by mass: water 100 parts; soluble copper salt 10-30 parts; potassium hydrogen phthalate 0.01-5 parts; complexing agent 0.01-5 parts; surfactant 0.01-1 part.

3. The PEI automotive lamp recycling method of claim 1, wherein, The soluble copper salt comprises one or more of copper sulfate, copper chloride and copper nitrate.

4. The PEI automotive lamp recycling method of claim 1, wherein, The complexing agent comprises one or more of tetrasodium ethylenediaminetetraacetate tetrahydrate, sodium tripolyphosphate, potassium sodium tartrate, sodium citrate and sodium gluconate.

5. The PEI automotive lamp recycling method of claim 1, wherein, The surfactant comprises one or more of sodium dodecylbenzenesulfonate, polyethylene glycol and glycerol.

6. The PEI automotive lamp recycling method of claim 1, wherein, The ultrasonic treatment is performed at 40-90℃ for 1-10h.

7. The PEI automotive lamp recycling method of claim 1, wherein, The ultrasonic treatment is performed at 40-70℃ for 1-3h.

8. The PEI automotive lamp recycling method of claim 1, wherein, The temperature for melting and granulation in step 3 is 250-360℃.

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