Method for catalytically degrading and plasticizing photovoltaic cross-linked material through multivalent metal manganese / cerium compound

Abstract

The invention discloses a method for catalytically degrading and plasticizing a photovoltaic cross-linked material through a multivalent metal manganese / cerium compound, aiming at a thermosetting adhesive film which is cross-linked in a molecular structure, after a plasticizer and a cosolvent are used for carrying out hot dipping pretreatment on cross-linked adhesive film powder, the multivalent metal manganese / cerium compound is used as a degradation catalyst of a system, and then the photovoltaic cross-linked material is degraded and plasticized through the multivalent metal manganese / cerium compound. Then the mixture obtained after hot dipping treatment is evenly mixed with thermoplastic resin and a polymerization inhibitor, melt extrusion is conducted under the strong mechanical shearing force of a double-screw extruder, and the obtained extrusion product has a certain flowing property. According to the invention, the plasticizable preparation of the photovoltaic cross-linked adhesive film can be realized by aiming at a large number of photovoltaic cross-linked materials with a certain degree of cross-linking, which are recycled from the industries of packaging adhesive films, functional greenhouse films, foaming shoe materials and the like of crystalline silicon photovoltaic cells through the process; the extruded product can be applied to polymer alloy as a toughening filling material of traditional engineering plastics or as an interface modifier.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a method for catalytic degradation and plasticization of photovoltaic crosslinked materials using multivalent manganese / cerium compounds. Background Technology

[0002] The main components of photovoltaic encapsulation film materials are ethylene-vinyl acetate (EVA) film, ethylene-polyolefin elastomer (POE) film, and mixed film, which are used to connect glass plates and crystalline silicon cells.

[0003] EVA is a non-toxic, odorless, transparent thermoplastic elastomer composed mainly of non-polar, crystalline ethylene monomers and non-crystalline vinyl acetate monomers. It is copolymerized in the presence of various additives, such as crosslinking agents, antioxidants, and stabilizers. It has excellent flexibility, impact resistance, elasticity, optical transparency, and corrosion resistance.

[0004] POE is a thermoplastic elastomer produced by in-situ polymerization of ethylene and α-olefins (such as 1-octene). It has excellent weather resistance, ozone resistance, UV resistance and aging resistance, and can maintain its performance stability under harsh environmental conditions.

[0005] In practical applications, photovoltaic encapsulation film materials often develop cross-linked structures in their molecular chains under the influence of cross-linking agents, coupling agents, and oxidation, losing their original thermoplastic properties. Because these cross-linked materials lose their melt-processable flow characteristics, they cannot be reused through traditional melt reprocessing after recycling. Currently, they can only be disposed of through landfill or incineration, but these methods lead to severe environmental pollution.

[0006] Therefore, exploring a processing method for degrading and plasticizing cross-linked photovoltaic films and obtaining new materials with melt-processability has enormous environmental and market value. Summary of the Invention

[0007] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0008] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0009] Therefore, the purpose of this invention is to overcome the shortcomings of the prior art and provide a method for catalytic degradation and plasticization of photovoltaic crosslinked materials by multivalent manganese / cerium compounds.

[0010] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for catalytic degradation and plasticization of photovoltaic crosslinked materials by multivalent manganese / cerium compounds, comprising, The recycled photovoltaic encapsulation film material is crushed and ground into powder to obtain film powder; the film powder, plasticizer, and co-solvent are mixed and sealed in an oven for hot impregnation treatment to obtain pre-plasticized mixture.

[0011] The catalyst, pre-plasticized mixture, thermoplastic resin, and polymerization inhibitor are mixed evenly in a high-speed mixer to obtain a mixture.

[0012] The recycled photovoltaic encapsulation film material is crushed and ground into powder to obtain the film powder.

[0013] After mixing the film powder, plasticizer, and co-solvent, the mixture is sealed and placed in an oven at 50-70°C for 10-15 hours to obtain a pre-plasticized mixture.

[0014] The catalyst, pre-plasticized mixture, thermoplastic resin, and polymerization inhibitor are mixed evenly in a high-speed mixer to obtain a mixture.

[0015] The mixture comprises, by mass percentage, 65-85% film powder, 10-20% thermoplastic resin, 0-10% plasticizer, 2-5% cosolvent, 0.2-1% catalyst, and 0.01-0.2% benzoquinone polymerization inhibitor.

[0016] The mixture is placed in a twin-screw extruder for extrusion and granulation. After extrusion, it is cooled with water and pelletized to obtain a flowable recycled product.

[0017] As a preferred embodiment of the method for catalytic degradation and plasticization of photovoltaic crosslinking materials by multivalent manganese / cerium compounds according to the present invention, the photovoltaic encapsulation film material includes one or more of ethylene-vinyl acetate film and ethylene-polyolefin elastomer film.

[0018] The plasticizer is an ester plasticizer with a boiling point greater than 180°C, including one or more of aliphatic diester plasticizers and phthalate plasticizers, wherein the phthalate plasticizers include one or more of diphenyl phthalate (DPH, boiling point 370°C) and dioctyl terephthalate (DOTP, boiling point 383°C).

[0019] As a preferred embodiment of the method for catalytic degradation and plasticization of photovoltaic crosslinked materials by multivalent manganese / cerium compounds according to the present invention, the co-solvent includes one or more of styrene, α-methylstyrene, and ethylstyrene.

[0020] As a preferred embodiment of the method for catalytic degradation and plasticization of photovoltaic crosslinked materials by multivalent manganese / cerium compounds described in this invention, the hot impregnation treatment is carried out at a temperature of 50~70℃ for 10~15h.

[0021] As a preferred embodiment of the method for catalytic degradation and plasticization of photovoltaic crosslinked materials by multivalent manganese / cerium compounds according to the present invention, wherein the catalyst is composed of manganese stearate and cerium acetate.

[0022] As a preferred embodiment of the method for catalytic degradation and plasticization of photovoltaic crosslinking materials by multivalent manganese / cerium compounds according to the present invention, wherein: the content of manganese stearate is 0.1~0.5% and the content of cerium acetate is 0.1~0.5% by mass percentage of the mixture.

[0023] As a preferred embodiment of the method for catalytic degradation and plasticization of photovoltaic crosslinking materials by multivalent manganese / cerium compounds according to the present invention, wherein the thermoplastic resin includes one or more of EVA, PP, and polyester resins.

[0024] As a preferred embodiment of the method for catalytic degradation and plasticization of photovoltaic crosslinked materials by multivalent manganese / cerium compounds according to the present invention, wherein the polymerization inhibitor is a benzoquinone-based polymerization inhibitor, including one or more of benzoquinone and linobenzoquinone.

[0025] As a preferred embodiment of the method for catalytic degradation and plasticization of photovoltaic crosslinked materials by multivalent manganese / cerium compounds according to the present invention, wherein the polymerization inhibitor is a benzoquinone-based polymerization inhibitor, including one or more of benzoquinone and linobenzoquinone.

[0026] The purpose of this invention is to overcome the shortcomings of the prior art and provide a blended modified product, wherein the melt index of the blended modified product after treatment is increased by more than 35 times compared with the original photovoltaic crosslinking material at 230°C and 10kg.

[0027] Beneficial effects of this invention: This invention prepares a mixture by mixing recycled photovoltaic crosslinked film with other additives, and then melt-extrudes it through a twin-screw extruder. Using multivalent manganese / cerium compounds as a catalyst, the crosslinked film is catalytically degraded and plasticized, enabling the continuous and rapid production of a series of blended graft products with high production efficiency.

[0028] The method for catalytic degradation and plasticization of photovoltaic crosslinking film materials by manganese / cerium compounds provided by this invention realizes the recycling and reuse of waste photovoltaic encapsulation materials. By adjusting and optimizing the formula used, extrusion products with good melt flow properties can be screened out, so as to be used as toughening fillers for traditional engineering plastics or as interface modifiers in polymer alloys. Detailed Implementation

[0029] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0030] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0031] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0032] Unless otherwise specified, all raw materials used in this invention are commercially available in the field.

[0033] The crosslinking degree of X-EVA powder used in this invention is 85.2%, and it is pulverized into powder with a particle size of 20~200 mesh. The polypropylene wax used in this invention has a melting point of 72°C.

[0034] The PP used in this invention is homopolymer PP, grade Z30S, with a melt index of 30g / 10min, and the EVA is Formosa Plastics 7760H, a C8 copolymer polyolefin elastomer with a melt index of 25g / 10min.

[0035] The MI test method of this invention refers to ASTM D 1238.

[0036] Example 1

[0037] This embodiment provides a method for catalytic degradation and plasticization of photovoltaic crosslinked materials using multivalent manganese / cerium compounds. Specifically: 1) Weigh the raw materials according to the following mass percentages, with a total mass of 6 kg: 70% X-EVA powder, 17.75% EVA (thermoplastic resin), 10% dioctyl phthalate (plasticizer), 2% methylstyrene (cosolvent), 0.1% manganese stearate (catalyst 1), 0.1% cerium acetate (catalyst 2), and 0.05% benzoquinone (polymerization inhibitor).

[0038] 2) X-EVA powder, dioctyl phthalate, and methyl styrene were mixed and sealed and placed in an oven at 60°C for 12 hours to obtain pre-plasticized G-EVA mixture; 3) Cerium acetate is fully dissolved in anhydrous ethanol to obtain cerium acetate liquid. The cerium acetate liquid, manganese stearate, and preplasticized mixture G-EVA, EVA, and benzoquinone are stirred evenly in a high-speed mixer. After the anhydrous ethanol has completely evaporated, a mixture is obtained. 4) The mixture is extruded and granulated in a twin-screw extruder. The screw speed is controlled at 200 r / min, the main motor current is 58%, and the temperatures of each section of the screw are: 150℃ in the front section, 170℃ in the middle section, and 190℃ in the rear section. The melt temperature is 180℃. The residence time of the melt in the screw is 2 min. After extrusion, the mixture is cooled with water and pelletized to obtain a flowable blended modified product.

[0039] Example 2

[0040] The difference between this embodiment and Embodiment 1 is that the amounts of thermoplastic resin and catalyst in the raw materials are adjusted. Specifically: Weigh the raw materials according to the following mass percentages, with a total mass of 6 kg: 70% X-EVA powder, 17.35% EVA (thermoplastic resin), 10% dioctyl phthalate (plasticizer), 2% methylstyrene (cosolvent), 0.3% manganese stearate (catalyst 1), 0.3% cerium acetate (catalyst 2), and 0.05% benzoquinone (polymerization inhibitor).

[0041] The host current in step 4) is adjusted to 67%, and the remaining steps are all in accordance with Example 1 to obtain the blended modified product of this example.

[0042] Example 3

[0043] The difference between this embodiment and Embodiment 1 is that the amounts of thermoplastic resin and catalyst in the raw materials are adjusted. Specifically: Weigh the raw materials according to the following mass percentages, with a total mass of 6 kg: 70% X-EVA powder, 16.95% EVA (thermoplastic resin), 10% dioctyl phthalate (plasticizer), 2% methylstyrene (cosolvent), 0.5% manganese stearate (catalyst 1), 0.5% cerium acetate (catalyst 2), and 0.05% benzoquinone (polymerization inhibitor).

[0044] The host current in step 4) is adjusted to 64%, and the remaining steps are all in accordance with Example 1 to obtain the blended modified product of this example.

[0045] Example 4

[0046] The difference between this embodiment and Example 1 is that the EVA in the raw materials is changed to PP. Specifically: Weigh the raw materials according to the following mass percentages, with a total mass of 6 kg: 70% X-EVA powder, 17.75% PP (thermoplastic resin), 10% dioctyl phthalate (plasticizer), 2% methylstyrene (cosolvent), 0.1% manganese stearate (catalyst 1), 0.1% cerium acetate (catalyst 2), and 0.05% benzoquinone (polymerization inhibitor).

[0047] The host current in step 4) is adjusted to 59%, and the remaining steps are all in accordance with Example 1 to obtain the blended modified product of this example.

[0048] Example 5

[0049] The difference between this embodiment and Embodiment 2 is that the EVA in the raw materials is changed to PP. Specifically: Weigh the raw materials according to the following mass percentages, with a total mass of 6 kg: 70% X-EVA powder, 17.35% PP (thermoplastic resin), 10% dioctyl phthalate (plasticizer), 2% methylstyrene (cosolvent), 0.3% manganese stearate (catalyst 1), 0.3% cerium acetate (catalyst 2), and 0.05% benzoquinone (polymerization inhibitor).

[0050] The host current in step 4) is adjusted to 62%, and the remaining steps are all in accordance with Example 2 to obtain the blended modified product of this example.

[0051] Example 6

[0052] The difference between this embodiment and Embodiment 3 is that the EVA in the raw materials is changed to PP. Specifically: Weigh the raw materials according to the following mass percentages, with a total mass of 6 kg: 70% X-EVA powder, 16.95% PP (thermoplastic resin), 10% dioctyl phthalate (plasticizer), 2% methylstyrene (cosolvent), 0.5% manganese stearate (catalyst 1), 0.5% cerium acetate (catalyst 2), and 0.05% benzoquinone (polymerization inhibitor).

[0053] The host current in step 4) is adjusted to 55%, and the remaining steps are all in accordance with Example 3 to obtain the blended modified product of this example.

[0054] The extrusion process stability, strip appearance, and melt flow index of the blended modified products of Examples 1 to 6 were tested, and the results are shown in Table 1.

[0055] Table 1

[0056] As can be seen from Table 1, the present invention uses multivalent metal manganese / cerium compounds as catalysts for the blend extrusion system. Under the high temperature mechanical shear force of the twin-screw extruder, the cross-linked X-EVA chains are broken, and during the extrusion process, it forms a blended alloy product with thermoplastic EVA or PP resin, which makes the originally non-flowing cross-linked film have a certain flow and plasticizes the original thermosetting film.

[0057] Comparative Example 1

[0058] The difference between this comparative example and Example 5 is that the catalyst is omitted and the amount of thermoplastic resin is adjusted accordingly. Specifically: Weigh the raw materials according to the following mass percentages, with a total mass of 6 kg: 70% X-EVA powder, 19.75% PP (thermoplastic resin), 10% dioctyl phthalate (plasticizer), 2% methylstyrene (cosolvent), and 0.05% benzoquinone (polymerization inhibitor).

[0059] The host current in step 4) was adjusted to 69%, and the remaining steps were performed in accordance with Example 5 to obtain the blended modified product of this comparative example.

[0060] Comparative Example 2

[0061] The difference between this comparative example and Example 5 is that only manganese stearate is used as a catalyst, and the amount of thermoplastic resin is adjusted accordingly. Specifically: Weigh the raw materials according to the following mass percentages, with a total mass of 6 kg: 70% X-EVA powder, 17.65% EVA (thermoplastic resin), 10% dioctyl phthalate (plasticizer), 2% methylstyrene (cosolvent), 0.3% manganese stearate (catalyst 1), and 0.05% benzoquinone (polymerization inhibitor).

[0062] The host current in step 4) was adjusted to 64%, and the remaining steps were performed in accordance with Example 5 to obtain the blended modified product of this comparative example.

[0063] Comparative Example 3

[0064] The difference between this comparative example and Example 5 is that only cerium acetate is used as a catalyst, and the amount of thermoplastic resin is adjusted accordingly. Specifically: Weigh the raw materials according to the following mass percentages, with a total mass of 6 kg: 70% X-EVA powder, 17.65% EVA (thermoplastic resin), 10% dioctyl phthalate (plasticizer), 2% methylstyrene (cosolvent), 0.3% cerium acetate (catalyst 1), and 0.05% benzoquinone (polymerization inhibitor).

[0065] The host current in step 4) was adjusted to 64%, and the remaining steps were performed in accordance with Example 5 to obtain the blended modified product of this comparative example.

[0066] The extrusion process stability, strip appearance, and melt flow index of the blended modified products of Comparative Examples 1 to 3 were tested and compared with those of Example 5. The results are shown in Table 2.

[0067] Table 2

[0068] As can be seen from Table 2, compared with Example 5, the products obtained by Comparative Examples 2 and 3 using a single catalyst have a lower melt index, but have higher fluidity than Comparative Example 1 without catalyst. This indicates that the catalysts manganese stearate and cerium acetate have a certain promoting effect on the plasticization preparation of X-EVA.

[0069] Comparative Example 4

[0070] The difference between this comparative example and Example 5 is that the catalyst 1, manganese stearate, is replaced with the traditional lubricating and mold-release agent, zinc stearate. The remaining steps and processes are the same as in Example 5, resulting in the blended modified product of this comparative example.

[0071] Comparative Example 5

[0072] The difference between this comparative example and Example 5 is that the catalyst 2, cerium acetate, is replaced with the lubricating release agent, zinc stearate. The remaining steps and processes are the same as in Example 5, resulting in the blended modified product of this comparative example.

[0073] Comparative Example 6

[0074] The difference between this comparative example and Example 5 is that the co-solvent α-methylstyrene is removed, the amount of polypropylene (PP) is increased proportionally, and the remaining steps and processes are the same as in Example 5, resulting in the blended modified product of this comparative example.

[0075] Comparative Example 7

[0076] The difference between this comparative example and Example 5 is that the co-solvent α-methylstyrene is increased to 6%, and the amount of polypropylene (PP) is reduced proportionally. The remaining steps and processes are the same as in Example 5, resulting in the blended modified product of this comparative example.

[0077] The extrusion process stability, strip appearance, and melt flow index of the blended modified products of Comparative Examples 4 to 7 were tested and compared with those of Example 5. The results are shown in Table 3.

[0078] Table 3

[0079] Table 3 shows that simply adding other lubricants (Comparative Examples 4-5), such as zinc stearate, does not effectively improve the flow properties of X-EVA. Adding low-molecular-weight co-solvents with unsaturated bonds, such as α-methylstyrene, can plasticize X-EVA resin, thus reducing its strength at high temperatures, leading to more chain scission of cross-linked EVA under high shear. Simultaneously, the free radicals formed by the broken-chain X-EVA can further initiate cross-linking of unsaturated bonds, reducing the probability of further cross-linking of the cross-linked film. In Comparative Example 6, the excessive content of low-molecular-weight co-solvents easily volatilizes or remains at high temperatures, ultimately leading to a deterioration of the production environment.

[0080] This invention discloses a method for the catalytic degradation and plasticization of photovoltaic crosslinked film materials using manganese / cerium compounds. For already crosslinked photovoltaic films (X-EVA / X-POE), the powder obtained by grinding the film with plasticizers and co-solvents undergoes hot impregnation pretreatment. Under the catalytic action of multivalent manganese / cerium compounds, it is mixed with thermoplastic resin and polymerization inhibitor, and then co-extruded in an extruder to obtain an alloy material (R-EVA / R-POE) with certain flowability for the recyclable photovoltaic crosslinked film, thus achieving the plasticization preparation of photovoltaic crosslinked films. This invention can be applied to the encapsulation films of crystalline silicon cells, functional greenhouse films, foamed shoe materials, and other industries using large quantities of recycled pre-crosslinked sheets. Through the above process, the obtained blended alloy has melt-processable characteristics, and the extruded product can be used as a toughening filler for traditional engineering plastics or as an interface modifier in polymer alloys.

[0081] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for catalytic degradation and plasticization of photovoltaic crosslinked materials via multivalent manganese / cerium compounds, characterized in that: include, The recycled photovoltaic encapsulation film material is crushed and ground into powder to obtain the film powder. After mixing the film powder, plasticizer, and co-solvent, the mixture is sealed and placed in an oven at 50-70°C for 10-15 hours to obtain a pre-plasticized mixture. The catalyst, preplasticized mixture, thermoplastic resin, and polymerization inhibitor are mixed evenly in a high-speed mixer to obtain a mixture; The mixture comprises, by mass percentage, 65-85% film powder, 10-20% thermoplastic resin, 0-10% plasticizer, 2-5% cosolvent, 0.2-1% catalyst, and 0.01-0.2% benzoquinone polymerization inhibitor; The mixture is placed in a twin-screw extruder for extrusion and granulation. After extrusion, it is cooled with water and pelletized to obtain a flowable recycled product.

2. The method for catalytic degradation and plasticization of photovoltaic crosslinked materials via multivalent manganese / cerium compounds as described in claim 1, characterized in that: The degree of crosslinking of the photovoltaic encapsulation film material is 65-90%, and its melt index is less than 0.1g / 10min under the conditions of 230℃ and 10kg.

3. The method for catalytic degradation and plasticization of photovoltaic crosslinked materials via multivalent manganese / cerium compounds as described in claim 2, characterized in that: The photovoltaic encapsulation film material includes one or more of ethylene-vinyl acetate film and ethylene-polyolefin elastomer film. The plasticizer is an ester plasticizer with a boiling point greater than 180°C, including one or more of aliphatic diester plasticizers and phthalate / terephthalate plasticizers; wherein the phthalate / terephthalate plasticizers include one or more of diphenyl phthalate and dioctyl terephthalate.

4. The method for catalytic degradation and plasticization of photovoltaic crosslinked materials via multivalent manganese / cerium compounds as described in claim 3, characterized in that: The co-solvent includes one or more of styrene, α-methylstyrene, and ethylstyrene.

5. The method for catalytic degradation and plasticization of photovoltaic crosslinked materials via multivalent manganese / cerium compounds as described in claim 1, characterized in that: The catalyst is composed of manganese stearate and cerium acetate.

6. The method for catalytic degradation and plasticization of photovoltaic crosslinked materials via multivalent manganese / cerium compounds as described in claim 5, characterized in that: The amount of manganese stearate and the amount of cerium acetate are 0.1-0.5% by mass percentage of the mixture.

7. The method for catalytic degradation and plasticization of photovoltaic crosslinked materials via multivalent manganese / cerium compounds as described in claim 1, characterized in that: The thermoplastic resin includes one or more of EVA, PP, and polyester resins.

8. The method for catalytic degradation and plasticization of photovoltaic crosslinked materials via multivalent manganese / cerium compounds as described in claim 7, characterized in that: The polymerization inhibitor is a benzoquinone-based polymerization inhibitor, including one or more of benzoquinone and alphabenzoquinone.

9. The method for catalytic degradation and plasticization of photovoltaic crosslinked materials via multivalent manganese / cerium compounds as described in claim 8, characterized in that: The mixture is extruded and granulated in a twin-screw extruder, wherein the screw speed is 100~300 r / min and the main screw current is 40~70%. In the extrusion granulation process, the temperatures of each section of the screw are as follows: The melt temperature is 170~190℃, with the first section at 140~170℃, the middle section at 170~180℃, and the last section at 180~190℃. The melt residence time in the screw is 1~3 minutes, and after extrusion, it is cooled with water and pelletized.

10. A blended modified product obtained by the method as described in claims 1-9, characterized in that: The blended modified product, after treatment, has a melt index that is more than 35 times higher than that of the original photovoltaic crosslinked material at 230°C and 10kg.

Images