An intercalating agent for separating solar backsheet and application thereof

Abstract

This invention discloses an intercalating agent for separating solar backsheets, comprising the following raw materials by mass percentage: 1.0 wt %~1.2 wt % OEP-70, 11 wt %~13 wt % sodium hydroxide, 5 wt %~6 wt The additive comprises glycerol, with the remainder being deionized water, and the sum of the mass percentages of all raw materials is 100%. This intercalating agent for separating solar backsheets uses OEP-70 as its core active ingredient, combined with sodium hydroxide and glycerol. The synergistic effect of these components in the separation liquid allows for precise control of the liquid's surface energy, enabling rapid penetration into the bonding interfaces of each layer of the solar backsheet, effectively disrupting adhesive bonding, and simultaneously maximally inhibiting the degradation of materials such as PET and PVDF. This invention also discloses the application of this intercalating agent for separating solar backsheets, achieving a 100% separation rate for various commercially available solar backsheets, with a separation time ≤10 h. The separated materials retain good properties and can be directly recycled, making it suitable for large-scale industrial production and possessing significant economic, environmental, and industrial value.

Description

Technical Field

[0001] This invention relates to the field of solar backsheet recycling technology, specifically to an intercalating agent for solar backsheet separation and its application. Background Technology

[0002] As a core industry of global clean new energy, the photovoltaic (PV) industry has seen my country rank first in the world in terms of installed capacity. With the 25-year lifespan of PV modules gradually approaching, the recycling and resource utilization of waste PV modules has become a key issue for the industry's sustainable development. Solar backsheets are the core encapsulation material of PV modules, mainly composed of multiple layers of composite materials such as fluorinated films (PVDF / PVF), PET films, and EVA, bonded together with adhesives. Efficient separation of these layers is a crucial step in PV waste recycling.

[0003] Due to the strong chemical inertness and low surface energy of fluorinated films, PET films are prone to hydrolytic degradation under alkaline and high-temperature conditions. This makes it difficult for traditional paint removers and adhesive removers to penetrate the interlayer bonding interface of the backsheet, resulting in low separation efficiency. While increasing the alkali concentration or reaction temperature can improve the separation effect, it will cause severe degradation of PET and PVDF materials, rendering them unusable for recycling. Existing intercalators also have a narrow range of applications, only capable of separating single types of backsheets and unable to adapt to various structural backsheets such as TPT, KPE, and KPO currently available commercially. Furthermore, some intercalators contain irritating or toxic components, which can easily cause secondary pollution, and their high raw material costs make large-scale application difficult.

[0004] Therefore, developing an intercalating agent that has good penetration, can inhibit material degradation, has high separation efficiency, wide applicability, and is environmentally friendly and economical, along with a simple and easy-to-implement application process, has become an urgent technical challenge to be solved in the field of solar backsheet recycling. Summary of the Invention

[0005] The purpose of this invention is to provide an intercalating agent for separating solar backsheets and its application, which solves the problems of poor permeability, severe material degradation, low separation efficiency and narrow applicability of existing intercalating agents, and realizes efficient, environmentally friendly and large-scale separation of various solar backsheets.

[0006] To achieve the above objectives, the solution of the present invention is: An intercalating agent for separating solar backsheets, comprising the following raw materials by mass percentage: 1.0 wt % ~1.2 wt % OEP-70, 11 wt % ~ 13 wt % sodium hydroxide, 5 wt % ~ 6 wt % glycerol, balance is deionized water, and the sum of the mass percentages of all raw materials is 100%.

[0007] An intercalating agent for separating solar backsheets, comprising the following raw materials by mass percentage: 1.0 wt %OEP-70, 12 wt % Sodium hydroxide, 6 wt % glycerol, balance is deionized water, and the sum of the mass percentages of all raw materials is 100%.

[0008] An application of an intercalating agent for separating solar backsheets involves applying the intercalating agent to the recycling process of solar backsheets.

[0009] The recycling process for the solar backsheet includes the following steps: Step 1: First, remove impurities and aluminum frames from the surface of the waste solar back panel. Then, cold crush the solar back panel using a crusher to obtain crushed material with a particle size of 2-3 cm. Step 2: Then, put the crushed material into the reactor, add the intercalating agent for solar energy separation, control the liquid-solid ratio to 10 mL: 1 g, heat to 74~76℃, and stir at a constant temperature of 35~45 r / min for 5.5~6.5 h; Step 3: Then, separate the solid and liquid components after the reaction, collect the solid film mixture, and place it at 25°C with a density of 1.5 g / cm³. 3 In the zinc chloride or calcium chloride inorganic salt centrifugation separation liquid, centrifuge at 20000 r / min for 10 min, let stand for 30 min, and take advantage of the density difference between PET and fluorine-containing film to achieve complete separation of the two. After standing, the upper layer is PET film and the lower layer is PVDF / PVF fluorine-containing film. Step 4: Then, wash the sorted PET film and PVDF / PVF fluorinated film with deionized water 2-3 times to remove the residual intercalating agent on the surface, dry them at 60-70℃ until the moisture content is ≤0.3%, and then granulate them through an extruder to obtain recycled granules; Step 5: Finally, after removing impurities from the reaction waste liquid by flocculation, replenish the lost OEP-70, sodium hydroxide and glycerol to restore the initial raw material ratio of the intercalating agent for solar backsheet separation, and cycle it 3 to 5 times; after multiple cycles, the waste liquid is distilled to recover glycerol and reused in the preparation of the intercalating agent, and the wastewater after removing the waste alkali meets the discharge standards.

[0010] In step 5, the flocculation method involves first adjusting the pH of the reaction waste liquid to 6.5-8.5 with acetic acid or ammonia, then adding 2 mL of saturated polyaluminum chloride aqueous solution per L of reaction waste liquid, stirring at 200-300 r / min for 30-60 s, then stirring slowly at 50-100 r / min for 10-20 minutes, and finally letting it stand for 10-30 minutes before siphoning out the supernatant for reuse.

[0011] In step 5, the distillation method involves first filtering the recycled waste liquid through a plate and frame filter to remove suspended solids; then heating it to 120°C to remove low-boiling-point light components; and finally distilling it under reduced pressure at 1000 Pa and 180°C to vaporize, condense, and collect the glycerol.

[0012] In step 5, the specific method for removing waste alkali is to first adjust the pH to 6-9 by adding dilute sulfuric acid, then add 2 mL of saturated polyaluminum chloride aqueous solution per L of reaction waste liquid, stir at a speed of 200-300 r / min for 30-60 s, then stir slowly at a speed of 50-100 r / min for 10-20 minutes, and finally let it stand for 10-30 minutes, and finally filter with sand to remove suspended impurities and colloids to obtain qualified wastewater.

[0013] By adopting the above technical solution, the present invention provides an intercalating agent for separating solar backsheets. First, OEP-70, as the core intercalating and penetrating component, is non-toxic and non-irritating, with high surface activity. It can significantly reduce the surface energy of the intercalating agent, allowing it to quickly penetrate into the adhesive layer between the fluorinated film and the PET film, thereby disrupting the interfacial bonding force of the adhesive. Simultaneously, OEP-70 exhibits good compatibility with alkali and glycerol, with no side reactions occurring. Furthermore, its raw material cost is significantly lower than that of similar commercially available intercalating agents, and the proportion of OEP-70 is controlled at 1.0. wt %~1.2 wt %, less than 1 wt When the percentage is less than 1.2%, the penetration effect is insufficient, and the separation time is prolonged; above 1.2%, the penetration effect is insufficient, and the separation time is prolonged. wt At a concentration of 1%, there is no significant improvement in efficiency; instead, it increases raw material costs. Secondly, sodium hydroxide, as a degreasing agent, can disrupt the chemical structure of the adhesive in the solar backsheet, reducing interlayer bonding strength. Its ratio should be controlled at 1:1. wt %~13 wt %, preferably 12 wt At this concentration, complete adhesive debonding and 100% separation of the backing sheet are ensured, while the hydrolytic degradation of the PET film is maximally inhibited, preventing ester bond breakage and loss of material properties. Finally, glycerol, as a penetration enhancer and corrosion inhibitor, further improves the penetration ability of the intercalating agent and shortens the separation time. It also forms a slight protective film on the surface of PET and PVDF materials, inhibiting excessive corrosion of the materials by the alkaline solution. Its ratio is controlled at 5%. wt %~6 wt %, preferably 6% wt At this concentration, the effects of penetration enhancement and corrosion inhibition are balanced, resulting in optimal separation efficiency and material retention.

[0014] In the solar backsheet recycling process of this invention, step 1 uses cold crushing to avoid premature softening and adhesion of the solar backsheet material due to high temperatures. A particle size of 2-3 cm increases the contact area between the material and the intercalating agent while preventing material breakage and loss due to excessively small particle size. Step 2 uses optimal reaction temperature and time parameters to ensure sufficient penetration of the intercalating agent and complete debinding of the adhesive, achieving thorough separation of the backsheet layers, while avoiding material degradation caused by high temperatures and prolonged stirring. This recycling process is applicable to the separation of all commercially available solar backsheets, including TPT, FST-KPC (thick), KPE, KPO, KPC, KPF, and CPC, demonstrating strong versatility.

[0015] This invention discloses an intercalating agent for separating solar backsheets and its application, which has the following beneficial effects: 1. The synergistic effect of the components of the intercalating agent achieves a 100% separation rate for all commercial solar backsheets such as TPT, KPE, and KPO, with a separation time of ≤10h, which is far superior to traditional intercalating agents. The matching process does not require parameter adjustment for different backsheets and has a wide range of applications. 2. By precisely controlling the proportions of each component and the parameters of the separation process, the hydrolytic degradation of PET and PVDF is suppressed to the greatest extent. The decomposition temperature of the PET film obtained after separation reaches 380℃, and the tensile strength of the PVDF film reaches 34 MPa. All properties meet the requirements for recycling and can partially or completely replace pure raw materials. 3. The core component of the intercalating agent, OEP-70, is non-toxic and non-irritating, and produces no toxic byproducts. The raw materials are all industrial-grade conventional reagents, which are inexpensive. The intercalating agent can be recycled 3 to 5 times, further reducing the cost of use. The waste liquid can be treated by flocculation and distillation to recover glycerol, and the wastewater meets the discharge standards without secondary pollution. Detailed Implementation

[0016] To further explain the technical solution of the present invention, the present invention will be described in detail below through specific embodiments.

[0017] Example 1 An intercalating agent for separating solar backsheets, comprising the following raw materials by mass percentage: 1.0 wt %OEP-70 (industrial grade, 98% purity), 12 wt % Sodium hydroxide (industrial grade flake solid alkali), 6 wt % Glycerol (industrial grade, water content 0.4%), 81 wt % deionized water.

[0018] The preparation method of the intercalating agent for solar backsheet separation is as follows: according to the formula ratio, first add the measured amount of deionized water to the mixing tank, then add sodium hydroxide at room temperature, stir until completely dissolved, then add glycerol, stir for 10 min until uniformly mixed, finally add OEP-70, and continue stirring for 20 min until the system is uniform and transparent to obtain the intercalating agent for solar backsheet separation.

[0019] Example 2 An intercalating agent for separating solar backsheets, comprising the following raw materials by mass percentage: 1.1 wt %OEP-70 (industrial grade, 98% purity), 11 wt % Sodium hydroxide (industrial grade flake solid alkali), 5.5 wt % Glycerol (industrial grade, water content 0.5%), 82.4 wt % deionized water.

[0020] The preparation method of the intercalating agent for solar backsheet separation is as follows: according to the formula ratio, first add the measured amount of deionized water to the mixing tank, then add sodium hydroxide at room temperature, stir until completely dissolved, then add glycerol, stir for 10 min until uniformly mixed, finally add OEP-70, and continue stirring for 20 min until the system is uniform and transparent to obtain the intercalating agent for solar backsheet separation.

[0021] Example 3 An intercalating agent for separating solar backsheets, comprising the following raw materials by mass percentage: 1.2 wt %OEP-70 (industrial grade, 98% purity), 13 wt % Sodium hydroxide (industrial grade flake solid alkali), 5.0 wt % Glycerol (industrial grade, water content 0.3%), 80.8 wt % deionized water.

[0022] The preparation method of the intercalating agent for solar backsheet separation is as follows: according to the formula ratio, first add the measured amount of deionized water to the mixing tank, then add sodium hydroxide at room temperature, stir until completely dissolved, then add glycerol, stir for 10 min until uniformly mixed, finally add OEP-70, and continue stirring for 20 min until the system is uniform and transparent to obtain the intercalating agent for solar backsheet separation.

[0023] Comparative Example 1 The commercially available JFC-1 intercalating agent was used to replace OEP-70 in Example 1. Other components and proportions were the same as in Example 1, and the preparation method was the same as in Example 1.

[0024] Application Example 1 A process for recycling solar backsheets includes the following steps: Step 1: First, remove impurities and aluminum frames from the surface of the waste TPT type solar backsheet. Then, cold crush the solar backsheet using a crusher to obtain crushed material with a particle size of 2-3 cm. Step 2: Then, the crushed material is put into the reactor, and the intercalating agent for solar energy separation prepared in Example 1 is added. The liquid-solid ratio is controlled at 10 mL:1 g. The temperature is raised to 75°C and stirred at a constant temperature of 40 r / min for 6.0 h. Step 3: Then, separate the solid and liquid components after the reaction, collect the solid film mixture, and place it at 25°C with a density of 1.5 g / cm³. 3 In zinc chloride, centrifuge at 20000 r / min for 10 min, let stand for 30 min, and then use PET (1.35 g / cm³) to measure the concentration. 3 ) and fluorinated films (1.78 g / cm) 3 Due to the density difference, the two layers are completely separated. After standing, the upper layer is a PET film and the lower layer is a PVDF / PVF fluorinated film. Step 4: Then, the sorted PET film and PVDF / PVF fluorinated film are washed three times with deionized water to remove the residual intercalating agent on the surface. They are then dried at 65°C until the moisture content is 0.2%. After that, they are granulated by an extruder to obtain recycled granules. The recycled granules retain good properties and can be directly used to prepare unsaturated polyester resin, fluorinated products, etc., to realize resource recycling. Step 5: Finally, after removing suspended impurities from the reaction waste liquid through flocculation, replenish the lost OEP-70, sodium hydroxide and glycerol to restore the initial raw material ratio of the intercalating agent for solar backsheet separation. It can be recycled 5 times. After multiple cycles, the waste liquid is distilled to recover glycerol and reused in the preparation of the intercalating agent. The wastewater after removing the waste alkali meets the discharge standards.

[0025] Testing showed that the TPT type solar backsheet in this application had a separation rate of 100% and a separation time of 6 hours; the PET film had a yield of 72.45% and a decomposition temperature of 380℃; the PVDF film had a yield of 18.96%, a tensile strength of 34 MPa, and an elongation of 10%. All properties of the film met the requirements for recycling. The intercalating agent used for separating the solar backsheet was recycled 5 times, and the separation efficiency remained at 100%.

[0026] Application Example 2 A process for recycling solar backsheets includes the following steps: Step 1: First, remove impurities and aluminum frames from the surface of the waste KPE type solar backsheet. Then, cold crush the solar backsheet using a crusher to obtain crushed material with a particle size of 2-3 cm. Step 2: Then, the crushed material is put into the reactor, and the intercalating agent for solar energy separation prepared in Example 2 is added. The liquid-solid ratio is controlled at 10 mL:1 g. The temperature is raised to 75°C and stirred at a constant temperature of 40 r / min for 6.0 h. Step 3: Then, separate the solid and liquid components after the reaction, collect the solid film mixture, and place it at 25°C with a density of 1.5 g / cm³. 3 In calcium chloride, centrifuge at 20000 r / min for 10 min, let stand for 30 min, and then use PET (1.35 g / cm³) to measure the calcium chloride content. 3 ) and fluorinated films (1.78 g / cm) 3 Due to the density difference, the two layers are completely separated. After standing, the upper layer is a PET film and the lower layer is a PVDF / PVF fluorinated film. Step 4: Then, the sorted PET film and PVDF / PVF fluorinated film are washed three times with deionized water to remove the residual intercalating agent on the surface. They are then dried at 65°C until the moisture content is 0.2%. After that, they are granulated by an extruder to obtain recycled granules. The recycled granules retain good properties and can be directly used to prepare unsaturated polyester resin, fluorinated products, etc., to realize resource recycling. Step 5: Finally, after removing suspended impurities from the reaction waste liquid by flocculation, replenish the lost OEP-70, sodium hydroxide and glycerol to restore the initial raw material ratio of the intercalating agent for solar backsheet separation, and cycle it 4 times. After multiple cycles, the waste liquid is distilled to recover glycerol and reused for intercalating agent preparation. The wastewater after removing waste alkali meets the discharge standards.

[0027] Testing showed that the TPT type solar backsheet in this application had a separation rate of 100% and a separation time of 6 hours; the PET film had a yield of 84.07% and a decomposition temperature of 380℃; the PVDF film had a yield of 11.38%, a tensile strength of 34 MPa, and an elongation of 10%. All properties of the film met the requirements for recycling. The intercalating agent used for separating the solar backsheet was recycled 4 times, and the separation efficiency remained at 100%.

[0028] Application Example 3 A process for recycling solar backsheets includes the following steps: Step 1: First, remove impurities and aluminum frames from the surface of the waste FST-KPC (thick) solar backsheet. Then, cold crush the solar backsheet using a crusher to obtain crushed material with a particle size of 2-3 cm. Step 2: Then, the crushed material is put into the reactor, and the intercalating agent for solar energy separation prepared in Example 3 is added. The liquid-solid ratio is controlled at 10 mL:1 g, the temperature is raised to 75°C, and the mixture is stirred at a constant temperature of 40 r / min for 6.0 h. Step 3: Then, separate the solid and liquid components after the reaction, collect the solid film mixture, and place it at 25°C with a density of 1.5 g / cm³. 3 In zinc chloride, centrifuge at 20000 r / min for 10 min, let stand for 30 min, and then use PET (1.35 g / cm³) to measure the concentration. 3 ) and fluorinated films (1.78 g / cm) 3 Due to the density difference, the two layers are completely separated. After standing, the upper layer is a PET film and the lower layer is a PVDF / PVF fluorinated film. Step 4: Then, the sorted PET film and PVDF / PVF fluorinated film are washed three times with deionized water to remove the residual intercalating agent on the surface. They are then dried at 65°C until the moisture content is 0.2%. After that, they are granulated by an extruder to obtain recycled granules. The recycled granules retain good properties and can be directly used to prepare unsaturated polyester resin, fluorinated products, etc., to realize resource recycling. Step 5: Finally, after removing suspended impurities from the reaction waste liquid by flocculation, replenish the lost OEP-70, sodium hydroxide and glycerol to restore the initial raw material ratio of the intercalating agent for solar backsheet separation, and cycle it 3 times. After multiple cycles, the waste liquid is distilled to recover glycerol and reused in the preparation of the intercalating agent. The wastewater after removing the waste alkali meets the discharge standards.

[0029] Testing showed that the TPT type solar backsheet in this application had a separation rate of 100% and a separation time of 6 hours; the PET film had a yield of 84.67% and a decomposition temperature of 380℃; the PVDF film had a yield of 7.59%, a tensile strength of 34 MPa, and an elongation of 10%. All properties of the film met the requirements for recycling. The intercalating agent used for separating the solar backsheet was recycled three times, and the separation efficiency remained at 100%.

[0030] Application Example 4 A process for recycling solar backsheets includes the following steps: Step 1: First, remove impurities and aluminum frames from the surface of the waste TPT type solar backsheet. Then, cold crush the solar backsheet using a crusher to obtain crushed material with a particle size of 2-3 cm. Step 2: Then, put the crushed material into the reactor, add the intercalating agent prepared in Comparative Example 1, control the liquid-solid ratio to be 10mL:1g, heat to 75℃, and stir at a constant temperature of 40 r / min for 12 h. Step 3: Then, separate the solid and liquid components after the reaction, collect the solid film mixture, and place it at 25°C with a density of 1.5 g / cm³. 3 In zinc chloride, centrifuge at 20000 r / min for 10 min, let stand for 30 min, and then use PET (1.35 g / cm³) to measure the concentration.3 ) and fluorinated films (1.78 g / cm) 3 The density difference between the two layers is used to achieve stratification. After standing, the upper layer is a PET film and the lower layer is a PVDF / PVF fluorinated film. Step 4: Then, the sorted PET film and PVDF / PVF fluorinated film are washed three times with deionized water to remove the residual intercalating agent on the surface. They are then dried at 65°C until the moisture content is 0.2%, and then granulated by an extruder to obtain recycled granules. Step 5: Finally, after removing suspended impurities from the reaction waste liquid by flocculation, replenish the lost JFC-1, sodium hydroxide and glycerol to restore the initial raw material ratio of the intercalating agent, and cycle it 5 times. After multiple cycles, the waste liquid is distilled to recover glycerol and reused in the preparation of the intercalating agent. The wastewater after removing the waste alkali meets the discharge standards.

[0031] Testing revealed that extending the separation time to 12 hours reduced the PET film yield to 65%, and the PET film suffered severe hydrolytic degradation, with the decomposition temperature dropping to 320℃, failing to meet the requirements for recycling. Furthermore, the cost of JFC-1 raw material was 30% higher than that of OEP-70, resulting in poor economic viability.

[0032] In each application example, in step 5, the flocculation method involves first adjusting the pH of the reaction waste liquid to 8.5 with acetic acid or ammonia, then adding 2 mL of saturated polyaluminum chloride aqueous solution per L of reaction waste liquid, stirring at 200 r / min for 60 s, then stirring slowly at 50 r / min for 20 minutes, and finally letting it stand for 30 minutes before siphoning out the supernatant for reuse.

[0033] In step 5, the distillation method involves first filtering the recycled waste liquid through a plate and frame filter to remove suspended solids; then heating it to 120°C to remove low-boiling-point light components; and finally distilling it under reduced pressure at 1000 Pa and 180°C to vaporize, condense, and collect the glycerol.

[0034] In step 5, the specific method for removing waste alkali is to first adjust the pH to 6 by adding dilute sulfuric acid, then add 2 mL of saturated polyaluminum chloride aqueous solution per L of reaction waste liquid, stir at 200 r / min for 60 s, then stir slowly at 50 r / min for 20 minutes, and finally let it stand for 30 minutes. Finally, filter with sand to remove suspended impurities and colloids to obtain wastewater that meets the standards.

[0035] The above embodiments are not intended to limit the product form and style of the present invention. Any appropriate changes or modifications made by those skilled in the art should be considered as not departing from the patent scope of the present invention.

Claims

1. An intercalating agent for separating solar backsheets, characterized in that: By weight percentage, the raw materials include the following amounts: 1.0 wt % ~ 1.2 wt % OEP-70, 11 wt % ~ 13 wt % sodium hydroxide, 5 wt % ~ 6 wt % glycerol, balance is deionized water, and the sum of the mass percentages of all raw materials is 100%.

2. The intercalating agent for separating solar backsheets according to claim 1, characterized in that: By weight percentage, the raw materials include the following amounts: 1.0 wt % OEP-70, 12 wt % Sodium hydroxide, 6 wt % glycerol, balance is deionized water, and the sum of the mass percentages of all raw materials is 100%.

3. An application of an intercalating agent for separating solar backsheets, characterized in that: This refers to the process of applying the solar energy separation intercalating agent as described in claim 1 to the recycling process of solar backsheets.

4. The application of the intercalating agent for solar backsheet separation according to claim 3, characterized in that: The recycling process for the solar backsheet includes the following steps: Step 1: First, remove impurities and aluminum frames from the surface of the waste solar back panel. Then, cold crush the solar back panel using a crusher to obtain crushed material with a particle size of 2-3 cm. Step 2: Then, put the crushed material into the reactor, add the intercalating agent for solar energy separation, control the liquid-solid ratio to 10mL:1g, heat to 74~76℃, and stir at a constant temperature of 35~45 r / min for 5.5~6.5 h. Step 3: Then, separate the solid and liquid components of the reacted solid-liquid mixture, collect the solid film mixture, and place it at 25°C with a density of 1.5 g / cm³. 3 In the zinc chloride or calcium chloride inorganic salt centrifugation separation liquid, centrifuge at 20000 r / min for 10 min, let stand for 30 min, and take advantage of the density difference between PET and fluorine-containing film to achieve complete separation of the two. After standing, the upper layer is PET film and the lower layer is PVDF / PVF fluorine-containing film. Step 4: Then, wash the sorted PET film and PVDF / PVF fluorinated film with deionized water 2-3 times to remove the residual intercalating agent on the surface, dry them at 60-70℃ until the moisture content is ≤0.3%, and then granulate them through an extruder to obtain recycled granules; Step 5: Finally, after removing suspended impurities from the reaction waste liquid by flocculation, replenish the lost OEP-70, sodium hydroxide and glycerol to restore the initial raw material ratio of the intercalating agent for solar backsheet separation, and cycle it 3 to 5 times; after multiple cycles, the waste liquid is distilled to recover glycerol and reused for intercalating agent preparation, and the wastewater after removing waste alkali meets the discharge standards.

5. The application of the intercalating agent for solar backsheet separation according to claim 4, characterized in that: In step 5, the flocculation method involves first adjusting the pH of the reaction waste liquid to 6.5-8.5 with acetic acid or ammonia, then adding 2 mL of saturated polyaluminum chloride aqueous solution per L of reaction waste liquid, stirring at 200-300 r / min for 30-60 s, then stirring slowly at 50-100 r / min for 10-20 minutes, and finally letting it stand for 10-30 minutes before siphoning out the supernatant for reuse.

6. The application of the intercalating agent for solar backsheet separation according to claim 4, characterized in that: In step 5, the distillation method involves first filtering the recycled waste liquid through a plate and frame filter to remove suspended solids; then heating it to 120°C to remove low-boiling-point light components; and finally distilling it under reduced pressure at 1000 Pa and 180°C to vaporize, condense, and collect the glycerol.

7. The application of the intercalating agent for solar backsheet separation according to claim 4, characterized in that: In step 5, the specific method for removing waste alkali is to first adjust the pH to 6-9 by adding dilute sulfuric acid, then add 2 mL of saturated polyaluminum chloride aqueous solution per L of reaction waste liquid, stir at a speed of 200-300 r / min for 30-60 s, then stir slowly at a speed of 50-100 r / min for 10-20 minutes, and finally let it stand for 10-30 minutes. Finally, filter with sand to remove suspended impurities and colloids to obtain wastewater that meets the standards.