A method for preparing a flame retardant using waste solar photovoltaic panels

Abstract

The application provides a method for preparing a flame retardant by using a waste solar photovoltaic panel, and the preparation raw material of the method comprises a main flame retardant and an auxiliary flame retardant; the main flame retardant comprises a bio-based modified flame retardant and a triazine flame retardant; and the auxiliary flame retardant is regenerated silicon carbide. When the flame retardant provided by the application is used in a polyester material, the flame retardant has high tensile strength, cantilever beam notched impact strength and limiting oxygen index, and good flame retardancy when placed for a long time at a relatively high temperature; and the limiting oxygen index and the cantilever beam notched impact strength are less affected by the increase of temperature when placed for a long time at a higher temperature, and the decrease of the limiting oxygen index and the cantilever beam notched impact strength is not obvious.

Description

Technical Field

[0001] This invention belongs to the field of flame retardants, specifically relating to a method for preparing flame retardants using waste solar photovoltaic panels. Background Technology

[0002] A solar photovoltaic (PV) system is a facility that converts solar energy into direct current (DC) electricity using the photovoltaic effect of photovoltaic semiconductor materials. The core of a PV system is the solar photovoltaic panel, and the semiconductor materials used to generate electricity mainly include monocrystalline silicon, polycrystalline silicon, and amorphous silicon. Due to the renewable energy and social benefits of solar PV systems, the photovoltaic industry has developed rapidly.

[0003] However, after long-term operation, photovoltaic systems experience a decline in power generation efficiency, leading to the abandonment of a large number of solar photovoltaic panels. If these abandoned panels cannot be recycled, it not only wastes resources but also causes environmental pollution due to indiscriminate disposal. Current technologies for recycling abandoned solar photovoltaic panels mainly employ acid dissolution. However, acid dissolution primarily targets the removal and separation of ethylene-vinyl acetate copolymers and does not consider the reuse of silicon wafers. Further processing of the silicon wafers is required. Existing technologies involve using silicon wafers to prepare silicon carbide for recycling. Silicon carbide is used as a flame retardant due to its high-temperature stability and flame-retardant properties, but its flame retardancy is relatively poor.

[0004] Patent CN106633794B discloses a composite flame retardant and its application. It involves processing silicon carbide to prepare SiC-MoSi2, which is then combined with polydiphosphazene, triethyl phosphate, etc., to act as a flame retardant and improve its flame-retardant effect. However, after the flame retardant is added to polyester and other materials, the mechanical properties and limiting oxygen index of the product deteriorate after prolonged exposure at room temperature or high temperature. Addressing the existing problems with silicon carbide as a flame retardant, this invention aims to solve the problem of how to combine silicon carbide with other flame retardants so that the resulting flame retardant, when used in polyester and other materials, does not significantly reduce the mechanical properties and limiting oxygen index even after prolonged exposure at room temperature or high temperature. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing flame retardants using waste solar photovoltaic panels, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: The present invention provides a method for preparing flame retardants using waste solar photovoltaic panels, wherein the raw materials for preparing flame retardants using waste solar photovoltaic panels include a main flame retardant and a flame retardant auxiliary agent;

[0007] The main flame retardant includes a bio-based modified flame retardant and a triazine flame retardant;

[0008] The flame retardant is recycled silicon carbide.

[0009] In some embodiments of the present invention, the mass ratio of the bio-based modified flame retardant to the triazine flame retardant is 3-5:1.

[0010] In some embodiments of the present invention, the raw materials for preparing the bio-based modified flame retardant include brominated epoxy resin and natural phenolic compounds.

[0011] In some embodiments of the present invention, the natural phenolic compound includes at least one of phenol, nonylphenol, arylalkylphenol, cashew phenol, octylphenol, and bisphenol A.

[0012] In some embodiments of the present invention, the natural phenolic compound comprises at least one of arylalkylphenol and cashew phenol.

[0013] In some embodiments of the present invention, the preparation method of the bio-based modified flame retardant includes the following steps:

[0014] Brominated epoxy resin, natural phenolic compounds and antioxidants are added to a reaction vessel, heated and stirred thoroughly until dissolved. After adding catalyst one to the reaction vessel, the temperature is raised to 170-200℃ and the reaction is completed to obtain a bio-based modified flame retardant.

[0015] In some embodiments of the present invention, the mass ratio of the brominated epoxy resin to the natural phenolic compound is 1-3:1.

[0016] In some embodiments of the present invention, the catalyst is 0.5%-2% of the total mass of brominated epoxy resin and natural phenolic compounds.

[0017] In some embodiments of the present invention, catalyst one includes, but is not limited to, triphenylphosphine and triphenylphosphine bromide.

[0018] In some embodiments of the present invention, the raw materials for preparing the triazine flame retardant include cyanuric chloride and sodium p-aminobenzenesulfonate.

[0019] In some embodiments of the present invention, the method for preparing the triazine flame retardant includes the following steps:

[0020] Cyanuric chloride was added to an organic solvent and heated and stirred until dissolved. Then, an aqueous solution containing sodium p-aminobenzenesulfonate was added while stirring was continued to allow the reaction to proceed to completion. After purification, a triazine flame retardant was obtained.

[0021] In some embodiments of the present invention, the mass ratio of cyanuric chloride to sodium p-aminobenzenesulfonate is 1:1.5-4.

[0022] In some embodiments of the present invention, the method for preparing the recycled silicon carbide includes the following steps:

[0023] (1) Dismantle waste solar photovoltaic panels to obtain silicon wafers, crush and grind them to obtain silicon powder, and then mix and grind the silicon powder, activated carbon and catalyst II to obtain intermediate I;

[0024] (2) The intermediate obtained in step (1) is sintered at high temperature. During sintering, the environment is inert and the temperature is 1300-1500℃ for 4-6 hours. After cooling to room temperature, it is heated at 400-600℃ for 4-6 hours to obtain intermediate two.

[0025] (3) The intermediate obtained in step (2) is soaked in an acidic solution, washed repeatedly with water and dried to obtain regenerated silicon carbide.

[0026] In some embodiments of the present invention, the 10% hydrofluoric acid solution can be prepared by oneself or purchased as needed. In the embodiments of this application, it was obtained by purchase from Sichuan Pusi Ao Standard Technology Co., Ltd., with product number PCL-2023RY012-1L.

[0027] In some embodiments of the present invention, catalyst two includes, but is not limited to, iron oxide, iron oxide-molybdenum oxide, or iron oxide-vanadium oxide.

[0028] In some embodiments of the present invention, a method for preparing a flame retardant using waste solar photovoltaic panels is provided, wherein the raw materials for preparing the flame retardant using waste solar photovoltaic panels further include additives.

[0029] In some embodiments of the present invention, the additives include, but are not limited to, one or a mixture of several of dispersants, reinforcing agents, toughening agents, antioxidants, heat stabilizers, light stabilizers, and lubricants.

[0030] In some embodiments of the present invention, the adjuvants include at least a dispersant.

[0031] In some embodiments of the present invention, the dispersant comprises at least an organic dispersant.

[0032] In some embodiments of the present invention, the dispersant is a mixture of organic and inorganic dispersants.

[0033] In some embodiments of the present invention, the organic dispersant is one or a mixture of several of oleamide, ethylene bisoleamide, ethylene bisstearamide and erucamide.

[0034] In some embodiments of the present invention, the inorganic dispersant is one or a mixture of several of sodium lignosulfonate, sodium tripolyphosphate, sodium pyrophosphate, and sodium silicate.

[0035] Compared with the prior art, the beneficial effects of the present invention are: when the flame retardant provided in this application is used in polyester materials, it exhibits high tensile strength, cantilever beam notched impact strength, and limiting oxygen index when placed at relatively high temperatures for a long time, as well as good flame retardancy; and the limiting oxygen index and cantilever beam notched impact strength have a relatively small impact on the limiting oxygen index and cantilever beam notched impact strength when placed at room temperature for a long time, and the decrease in limiting oxygen index and cantilever beam notched impact strength is not significant. Detailed Implementation

[0036] The present invention will be described below with reference to specific embodiments. It should be noted that the following embodiments are examples of the present invention and are used only to illustrate the invention, not to limit it. Other combinations and various modifications within the scope of the present invention can be made without departing from its spirit or scope.

[0037] In the following examples, except for the bio-based modified flame retardant, triazine flame retardant, and recycled silicon carbide, all the compound monomers and related reagents used were commercially available. Specifically, the commercially available triazine flame retardant was purchased from Guangdong Fantian Technology Co., Ltd., model SR-245; the brominated epoxy resin was purchased from Suzhou Senfida Chemical Co., Ltd., model EMTE400; the cashew phenol was purchased from Shandong Changyao New Materials Co., Ltd., item number CY-F12; the cyanuric chloride was purchased from Jiangsu Bosite Chemical Technology Co., Ltd.; the waste solar photovoltaic panel was purchased from Qinhuangdao Sufu Electronics Co., Ltd., model SFZDM-70; the PBT resin was purchased from Dongguan Zhangmutou Dafeng Plastic Raw Material Business Department, item number CE2055; and the glass fiber was purchased from Lingshou County Yunda Mineral Products Co., Ltd., item number 002.

[0038] A method for preparing a bio-based modified flame retardant includes the following steps:

[0039] 100g of brominated epoxy resin, 48.35g of cashew nut phenol, 0.11g of antioxidant 1010, and 0.1g of antioxidant 168 were added to a reaction vessel and heated to 95℃. After stirring thoroughly until dissolved, 0.8g of triphenylphosphine catalyst was added to the reaction vessel, and the temperature was raised to 180℃. After reacting for 2 hours, the reaction was completed, and a bio-based modified flame retardant was obtained.

[0040] The method for preparing triazine flame retardants includes the following steps:

[0041] 15g of cyanuric chloride was added to 200mL of acetone and heated and stirred until dissolved (heated to 50℃). Then, stirring was continued and 55mL of an aqueous solution containing 0.15mol of sodium p-aminobenzenesulfonate was added. After reacting for 6h, the solvent was removed by vacuum distillation, purified by column chromatography, and then vacuum dried in a vacuum drying oven (temperature 40℃, drying time 10h) to obtain the triazine flame retardant. The eluent used in the column chromatography purification was methanol and toluene in a volume ratio of 2:3.

[0042] A method for preparing recycled silicon carbide includes the following steps:

[0043] (1) Dismantle waste solar photovoltaic panels to obtain silicon wafers, crush and grind them to obtain silicon powder. The average particle size of the silicon powder is 45μm. After mixing and grinding 20g silicon powder, 62g activated carbon and 1.7g iron oxide, intermediate one is obtained. The average particle size of intermediate one is 5μm.

[0044] (2) The intermediate obtained in step (1) is placed in the furnace for high-temperature sintering. Before sintering, the furnace is evacuated and argon gas is introduced to make the furnace atmosphere argon. The temperature is raised at 50-900℃ with a heating rate of 10℃ / min, and at 900-1500℃ with a heating rate of 6℃ / min. After the temperature is raised to 1500℃, it is sintered at a constant temperature for 4.5h. After cooling to room temperature, the product is heated at a constant temperature for 6h (the constant temperature heating temperature is 550℃) to obtain intermediate two.

[0045] (3) After soaking the intermediate II obtained in step (2) in a 10% hydrofluoric acid solution for 24 hours, it is repeatedly washed with water and dried (drying temperature is 40℃ and drying time is 12 hours) to obtain regenerated silicon carbide.

[0046] Example 1:

[0047] A method for preparing a flame retardant using waste solar photovoltaic panels, wherein the raw materials for preparing the flame retardant using waste solar photovoltaic panels, by weight, include 60 parts of bio-based modified flame retardant, 20 parts of triazine flame retardant, 10 parts of recycled silicon carbide, and 2 parts of ethylene bis-stearamide.

[0048] Example 2:

[0049] A method for preparing a flame retardant using waste solar photovoltaic panels, wherein the raw materials for preparing the flame retardant using waste solar photovoltaic panels, by weight, include 70 parts of bio-based modified flame retardant, 15 parts of triazine flame retardant, 8 parts of recycled silicon carbide, and 2.5 parts of ethylene bis-stearamide.

[0050] Example 3:

[0051] A method for preparing a flame retardant using waste solar photovoltaic panels, wherein the raw materials for preparing the flame retardant using waste solar photovoltaic panels, by weight, include 65 parts of bio-based modified flame retardant, 18 parts of triazine flame retardant, 12 parts of recycled silicon carbide, and 3 parts of ethylene bis-stearamide.

[0052] Example 4:

[0053] A method for preparing a flame retardant using waste solar photovoltaic panels, wherein the raw materials for preparing the flame retardant using waste solar photovoltaic panels, by weight, include 40 parts of bio-based modified flame retardant, 40 parts of triazine flame retardant, 10 parts of recycled silicon carbide, and 2 parts of ethylene bis-stearamide.

[0054] Example 5:

[0055] A method for preparing a flame retardant using waste solar photovoltaic panels, wherein the raw materials for preparing the flame retardant using waste solar photovoltaic panels, by weight, include 70 parts of bio-based modified flame retardant, 10 parts of triazine flame retardant, 10 parts of recycled silicon carbide, and 2 parts of ethylene bis-stearamide.

[0056] Comparative Example 1:

[0057] A method for preparing a flame retardant using waste solar photovoltaic panels, wherein the raw materials for preparing the flame retardant using waste solar photovoltaic panels, by weight, include 60 parts of brominated epoxy resin, 20 parts of triazine flame retardant, 10 parts of recycled silicon carbide, and 2 parts of ethylene bis-stearamide.

[0058] Comparative Example 2:

[0059] A method for preparing a flame retardant using waste solar photovoltaic panels, wherein the raw materials for preparing the flame retardant using waste solar photovoltaic panels, by weight, include 60 parts of bio-based modified flame retardant, 20 parts of commercially available triazine flame retardant, 10 parts of recycled silicon carbide, and 2 parts of ethylene bis-stearamide.

[0060] The preparation methods for flame retardants using waste solar photovoltaic panels in Examples 1-5 and Comparative Examples 1-2 include the following steps:

[0061] The raw materials and mass fractions corresponding to Examples 1-5 and Comparative Examples 1-2 were added to a mixer and stirred to obtain flame retardants. The stirring speed was 60 r / min and the stirring time was 5 min.

[0062] The method for preparing the polyester material using Examples 1-7 includes the following steps:

[0063] By weight, 12 parts of the flame retardant prepared in Examples 1-5 and Comparative Examples 1-2, 60 parts of PBT resin, 35 parts of glass fiber, and 0.6 parts of antioxidant 1010 were mixed and then extruded and granulated using a twin-screw extruder to obtain polyester material. The process parameters of the twin-screw extruder were set as follows: zone 1 temperature 210℃, zone 2 temperature 220℃, zone 3 temperature 220℃, zone 4 temperature 220℃, zone 5 temperature 220℃, zone 6 temperature 220℃, zone 7 temperature 220℃, zone 8 temperature 220℃, zone 9 temperature 220℃, and zone 10 temperature 220℃. The screw speed of the twin-screw extruder was 350 rpm.

[0064] The correspondence between the polyester materials used in Examples 1-7 and the flame retardants prepared in Examples 1-5 and Comparative Examples 1-2 is shown in Table 1 below:

[0065] Table 1

[0066]

[0067] The polyester materials prepared according to Examples 1-7 were placed in an environment with a temperature of 40℃ and a relative humidity of 50% for 30 days, and then subjected to tests for flame retardancy, tensile strength, cantilever beam notched impact strength, and limiting oxygen index. Simultaneously, the polyester materials prepared according to Examples 1-8 were placed in an environment with a temperature of 25℃ and a relative humidity of 50% for 30 days, and then subjected to tests for limiting oxygen index and cantilever beam notched impact strength. The test methods are as follows:

[0068] Flame retardancy test: Flame retardancy performance was tested according to UL-94 standard, with a sample thickness of 1.6 mm;

[0069] Tensile strength test: The tensile strength test was conducted according to GB / T 1040.2-2006 standard. The specimen type was 1A, and the unit was MPa.

[0070] Notched impact strength test of cantilever beam: The notched impact strength test of cantilever beam is performed according to ISO 180 standard. The specimen size is 80mm × 10mm × 4mm, and the unit is KJ / m. 2 ;

[0071] Limiting oxygen index test: The limiting oxygen index test was conducted according to GB / T 2406.2-2009 standard, and the sample size was 80mm×10mm×4mm.

[0072] The test results are shown in Table 2, as follows:

[0073] Table 2

[0074]

[0075] As can be seen from the comparison of Application Examples 1 and 4-5, when the mass ratio of bio-based modified flame retardant to triazine flame retardant is within a suitable range, the resulting flame retardant, when used in polyester materials, can further improve tensile strength, cantilever beam notched impact strength, and limiting oxygen index, as well as flame retardancy, even when placed at relatively high temperatures for a long time. Moreover, the limiting oxygen index and cantilever beam notched impact strength do not decrease significantly when placed at room temperature for a long time, but when placed at higher temperatures for a long time.

[0076] A comparison of Application Examples 1 and 6-7 shows that when the combination of bio-based modified flame retardants and triazine flame retardants is used to prepare flame retardants for polyester materials, they exhibit high tensile strength, cantilever beam notched impact strength, and limiting oxygen index (LOI) after prolonged exposure at relatively high temperatures, as well as good flame retardancy. Furthermore, the LIO and LIO values ​​are relatively stable after prolonged exposure at room temperature and at higher temperatures; the increase in temperature has a smaller impact on the LIO and LIO values, and the decrease in LIO and LIO values ​​is not significant.

[0077] As can be seen from the comparison of application examples 1-3, when the flame retardant provided in this application is used in polyester materials, it exhibits high tensile strength, cantilever beam notched impact strength, and limiting oxygen index, as well as good flame retardancy when placed at relatively high temperatures for a long time. Moreover, the limiting oxygen index and cantilever beam notched impact strength have a relatively small impact on the limiting oxygen index and cantilever beam notched impact strength when placed at higher temperatures for a long time, compared to when placed at room temperature. The decrease in limiting oxygen index and cantilever beam notched impact strength is not significant.

[0078] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing flame retardants using waste solar photovoltaic panels, characterized in that: The raw materials for preparing flame retardants using waste solar photovoltaic panels include a main flame retardant and a flame retardant auxiliary agent. The main flame retardant includes a bio-based modified flame retardant and a triazine flame retardant; The flame retardant is recycled silicon carbide.

2. The method for preparing flame retardants using waste solar photovoltaic panels according to claim 1, characterized in that: The mass ratio of the bio-based modified flame retardant to the triazine flame retardant is 3-5:

1.

3. The method for preparing flame retardants using waste solar photovoltaic panels according to claim 1, characterized in that: The raw materials for preparing the bio-based modified flame retardant include brominated epoxy resin and natural phenolic compounds.

4. The method for preparing flame retardants using waste solar photovoltaic panels according to claim 3, characterized in that: The preparation method of the bio-based modified flame retardant includes the following steps: Brominated epoxy resin, natural phenolic compounds and antioxidants are added to a reaction vessel, heated and stirred thoroughly until dissolved. After adding catalyst one to the reaction vessel, the temperature is raised to 170-200℃ and the reaction is completed to obtain a bio-based modified flame retardant.

5. The method for preparing a flame retardant using waste solar photovoltaic panels according to claim 3, characterized in that: The mass ratio of the brominated epoxy resin to the natural phenolic compound is 1-3:1, and the catalyst is 0.5%-2% of the total mass of the brominated epoxy resin and the natural phenolic compound.

6. The method for preparing flame retardants using waste solar photovoltaic panels according to claim 1, characterized in that: The raw materials for preparing the triazine flame retardant include cyanuric chloride and sodium p-aminobenzenesulfonate.

7. A method for preparing a flame retardant using waste solar photovoltaic panels according to claim 6, characterized in that: The method for preparing the triazine flame retardant includes the following steps: Cyanuric chloride was added to an organic solvent and heated and stirred until dissolved. Then, an aqueous solution containing sodium p-aminobenzenesulfonate was added while stirring was continued to allow the reaction to proceed to completion. After purification, a triazine flame retardant was obtained.

8. The method for preparing a flame retardant using waste solar photovoltaic panels according to claim 3, characterized in that: The mass ratio of cyanuric chloride to sodium p-aminobenzenesulfonate is 1:1.5-4.

9. A method for preparing a flame retardant using waste solar photovoltaic panels according to claim 1, characterized in that: The method for preparing the recycled silicon carbide includes the following steps: (1) Dismantle waste solar photovoltaic panels to obtain silicon wafers, crush and grind them to obtain silicon powder, and then mix and grind the silicon powder, activated carbon and catalyst II to obtain intermediate I; (2) The intermediate obtained in step (1) is sintered at high temperature. During sintering, the environment is inert and the temperature is 1300-1500℃ for 4-6 hours. After cooling to room temperature, it is heated at 400-600℃ for 4-6 hours to obtain intermediate two. (3) The intermediate obtained in step (2) is soaked in an acidic solution, washed repeatedly with water and dried to obtain regenerated silicon carbide.

10. A method for preparing a flame retardant using waste solar photovoltaic panels according to claim 1, characterized in that: The raw materials for preparing flame retardants using waste solar photovoltaic panels also include additives.

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