A recycling method of FEP cast film edge material, recycled FEP cast film and application thereof

Abstract

The application provides a recycling method of FEP casting film edge material, recycled FEP casting film and application thereof. The recycling method first granulates the FEP casting film edge material to obtain recycled material particles, then blends the obtained recycled material particles, FEP resin and color masterbatch to obtain blended raw materials, and finally melts and extrudes the obtained blended raw materials, calender cools and forms, drags and flattens, cuts edges and winds up, so as to obtain the recycled FEP casting film and complete the recycling of the FEP casting film edge material. The recycling method can effectively improve the utilization rate of the FEP resin, greatly solves the reuse problem of the FEP casting film edge material of the same grade, and can also ensure that the recycled FEP casting film has excellent tensile properties and puncture resistance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of cast film and particularly relates to a recycling method of FEP cast film edge material, recycled FEP cast film and application thereof. BACKGROUND

[0002] In recent years, the development of the aviation field is extremely rapid, with the smooth delivery and expansion of large aircraft, the consumption of high-temperature isolation film gradually increases. FEP is the abbreviation of Fluorinated ethylene propylene, and its Chinese name is perfluoroethylene propylene copolymer, commonly known as F46. As is known to all, FEP is the main raw material for producing high-temperature isolation film, and its price is high and in short supply.

[0003] FEP cast film is formed by taking FEP resin as the main raw material through a casting process. The advantage of the casting process technology lies in its high efficiency, economy and sustainability. The plastic film prepared by the casting process technology has high transparency, flexibility and mechanical strength, and can be widely applied in the fields of aerospace and electronic materials. However, the finished product utilization rate of the cast film product is difficult to reach 100% after edge cutting and winding. Especially in the field of FEP cast film, the finished product utilization rate is less than 75%, and the edge material accounts for more than 25%, which causes a great waste of raw materials. In addition, due to the large specific gravity of FEP cast film, the thickness of the finished product is thin, and the finished product film is generally between 10-50 microns. The broken product at room temperature is easily blocked in the feeding port, which affects the production and causes great difficulty in recycling.

[0004] Therefore, in view of the above technical problems, it is urgent to develop a recycling method of FEP cast film edge material to improve the utilization rate of FEP. SUMMARY

[0005] In view of the deficiencies of the prior art, the purpose of the present application is to provide a recycling method of FEP cast film edge material, recycled FEP cast film and application thereof. The recycling method can effectively improve the utilization rate of FEP resin, greatly solve the reuse problem of FEP cast film edge material of the same grade, and also ensure that the recycled FEP finished product film has excellent tensile properties and puncture resistance.

[0006] To achieve this purpose, the following technical solutions are adopted in the present application:

[0007] In a first aspect, the present application provides a recycling method of FEP cast film edge material, which comprises the following steps:

[0008] (1) Granulation: granulating the FEP cast film edge material to obtain recycled material particles;

[0009] (2) blending: blending the recycled material particles obtained in step (1), FEP resin and color masterbatch to obtain a blended raw material;

[0010] (3) film making: melt extruding, calendering and cooling molding, traction flattening, edge cutting and winding of the blended raw material obtained in step (2) to obtain a recycled FEP casting film, completing the recycling of the FEP casting film edge material.

[0011] The FEP casting film edge material recycling method provided by the application first directly granulates the FEP casting film edge material without any pretreatment to obtain recycled material particles, then blends the obtained recycled material particles with FEP resin and color masterbatch to obtain a blended raw material, and finally melt extrudes, calendering and cooling molds, traction flattens and edge cuts and winds the obtained blended raw material to obtain a recycled FEP casting film, completing the recycling of the FEP casting film edge material. The FEP casting film edge material recycling method provided by the application not only has simple operation, but also greatly solves the reuse problem of FEP casting film edge material of the same grade, so that the utilization rate of FEP resin reaches 100%, and the performance of the finally made recycled FEP casting film does not decrease obviously, has excellent tensile properties and puncture resistance, indicating that the edge material can be fully utilized.

[0012] In the application, the edge material produced in the edge cutting process by using FEP resin and color masterbatch as blended raw material is defined as FEP casting film edge material with 1 recycling times, denoted as F1; the edge material produced in the edge cutting process by using FEP casting film edge material with 1 recycling times (F1), FEP resin and color masterbatch as blended raw material is defined as FEP casting film edge material with 2 recycling times, denoted as F2, and so on.

[0013] Preferably, the FEP casting film edge material includes edge material (F1) produced in the edge cutting process by using brand new FEP resin and color masterbatch as blended raw material,

[0014] and / or edge material (denoted as F2, F3, F4 or F5) produced in the edge cutting process by using FEP casting film edge material with ≤5 recycling times (such as 5, 4, 3 or 2, etc.), FEP resin and color masterbatch as blended raw material.

[0015] Preferably, the granulation in step (1) is carried out in a single screw granulator.

[0016] Preferably, the single screw of the single screw granulator has a length to diameter ratio of 1 :20 or more (e.g. 1 :21, 1 :22, 1 :24, 1 :26, 1 :28 or 1 :30, etc.), the temperatures from the feeding port to each zone are in turn: the feeding port is 200-400°C (e.g. 200°C, 250°C, 300°C, 350°C or 400°C, etc.), zone 1 is 200-400°C (e.g. 200°C, 250°C, 300°C, 350°C or 400°C, etc.), zone 2 is 200-400°C (e.g. 200°C, 250°C, 300°C, 350°C or 400°C, etc.), zone 3 is 200-400°C (e.g. 200°C, 250°C, 300°C, 350°C or 400°C, etc.), zone 4 is 200-400°C (e.g. 200°C, 250°C, 300°C, 350°C or 400°C, etc.), and the length of each zone is independently 10-20 cm (e.g. 10 cm, 12 cm, 14 cm, 16 cm, 18 cm or 20 cm, etc.), the temperature of the screen changer is 250-370°C (e.g. 250°C, 270°C, 290°C, 310°C, 350°C or 370°C, etc.), the filter screen is at least three layers of filtration, each layer of filtration has a precision of at least 80 mesh (e.g. 80 mesh, 100 mesh or 120 mesh, etc.), and the temperature of the die is 250-370°C (e.g. 250°C, 270°C, 290°C, 310°C, 350°C or 370°C, etc.).

[0017] Preferably, the single screw of the single screw granulator has a length to diameter ratio of 1 :20 or more, the temperatures from the feeding port to each zone are in turn: the feeding port is 240-260°C, zone 1 is 240-260°C, zone 2 is 260-280°C, zone 3 is 260-280°C, zone 4 is 260-280°C, and the length of each zone is independently 10-20 cm, the temperature of the screen changer is 260-280°C, the filter screen is at least five layers of filtration, stacked in the order 80 mesh / 80 mesh / 100 mesh / 100 mesh / 120 mesh, and the temperature of the die is 260-280°C.

[0018] Preferably, during the granulation of step (1), the entire heating time from feeding to discharging is controlled to be 30-180 s (e.g. 30 s, 40 s, 60 s, 80 s, 100 s, 120 s, 140 s, 160 s or 180 s, etc.), the cold compressed air is turned on, the die rotation slicing is turned on, the rotation speed of the cutter is adjusted according to the size of the granules, and the rotation speed of the cutter is not less than 25 Hz (e.g. 25 Hz, 26 Hz, 27 Hz, 29 Hz, 31 Hz, 33 Hz, 35 Hz, 37 Hz, 39 Hz or 40 Hz, etc.).

[0019] Preferably, the mass percentage of the recycled material particles is 25-40% (for example 25%, 27%, 29%, 31%, 33%, 35%, 37%, 39% or 40%, etc.), the mass percentage of the FEP resin is 50-75% (for example 50%, 55%, 60%, 65%, 70% or 75%, etc.), and the mass percentage of the color masterbatch is 1-10% (for example 1%, 2%, 4%, 6%, 8% or 10%, etc.), based on the total mass of the raw material in step (2).

[0020] Preferably, the FEP resin has a melt index of 1-20 g / 10 min, for example 1 g / 10 min, 2 g / 10 min, 4 g / 10 min, 6 g / 10 min, 8 g / 10 min, 10 g / 10 min, 12 g / 10 min, 14 g / 10 min, 16 g / 10 min, 18 g / 10 min or 20 g / 10 min, etc., and the test temperature of the melt index is 375°C and the load is 5 kg.

[0021] Preferably, the melt extrusion process in step (3) specifically includes: melting the raw material into the extruder, extruding from the T-shaped die head of the casting machine, uniformly blowing up and adhering to the casting cooling roller by the air knife, obtaining the extruded blank film, and completing the melt extrusion.

[0022] Preferably, the melting temperature is 330-380°C (for example 330°C, 340°C, 350°C, 360°C, 370°C or 380°C, etc.), the lip gap of the die head is 0.02-0.07 mm (for example 0.02 mm, 0.03 mm, 0.04 mm, 0.05 mm, 0.06 mm or 0.07 mm, etc.), the extrusion temperature of the die head is 350-380°C (for example 350°C, 355°C, 360°C, 370°C or 380°C, etc.), and the air pressure of the air knife is 0.2-0.7 MPa (for example 0.2 MPa, 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa or 0.7 MPa, etc.).

[0023] Preferably, the calender cooling molding process in step (3) specifically includes: shaping the extruded blank film through the cooling roller to obtain the FEP film.

[0024] Preferably, the cooling roller is cooled by conducting heat transfer oil, and after passing through the internal cooling heat exchanger of the cooling roller, the temperature of the cooling roller is controlled at 120-180°C (for example 120°C, 140°C, 160°C or 180°C, etc.), and the rotating speed of the cooling roller is 1-10 m / min (for example 1 m / min, 2 m / min, 4 m / min, 6 m / min, 8 m / min or 10 m / min, etc.).

[0025] In a second aspect, the present application provides a recycled FEP cast film prepared by the recycling method of the first aspect.

[0026] Preferably, the MD tensile strength of the recycled FEP cast film is not less than 43 MPa (e.g. 43 MPa, 43.5 MPa, 44 MPa, 44.5 MPa, 45 MPa, 46 MPa, 48 MPa or 50 MPa, etc.), and the TD tensile strength is not less than 37 MPa (e.g. 37 MPa, 38 MPa, 39 MPa, 40 MPa, 41 MPa, 42 MPa, 43 MPa, 44 MPa or 45 MPa, etc.).

[0027] In a third aspect, the present application provides use of the recycled FEP cast film of the second aspect in the process of composite material forming.

[0028] Compared with the prior art, the present application has the following beneficial effects:

[0029] The recycling method of the FEP cast film provided by the present application first granulates the FEP cast film scrap to obtain recycled material particles, then blends the obtained recycled material particles, FEP resin and color masterbatch to obtain blended raw materials, and finally melt extrudes, calender cools, stretches, trims and winds the obtained blended raw materials to obtain a recycled FEP cast film, thereby completing the recycling of the FEP cast film scrap. The recycling method can effectively improve the utilization rate of FEP resin, greatly solve the reuse problem of FEP cast film scrap of the same grade, and also ensure that the recycled FEP cast film has excellent tensile properties and puncture resistance. DETAILED DESCRIPTION

[0030] The technical solutions of the present application will be further described by specific embodiments. Those skilled in the art should understand that the embodiments are only to help understand the present application and should not be regarded as specific limitations of the present application.

[0031] Some raw material information involved in the following specific embodiments is shown as follows:

[0032] (1) FEP Resin A: melt index 6 g / 10 min (375℃ / 5 kg), purchased from Daikin, model NP-20;

[0033] (2) FEP Resin B: melt index 18 g / 10 min (375℃ / 5 kg), purchased from Dongyue, model 618B;

[0034] (3) Color Masterbatch: Kolan FEP Color Masterbatch 198.8.

[0035] Preparation Example 1

[0036] A preparation method of FEP cast film, specifically comprising the following steps:

[0037] (1) blending: blending FEP resin A with a mass percentage of 95% and color masterbatch with a mass percentage of 5% to obtain a blended raw material;

[0038] (2) melt extrusion: adding the obtained blended raw material into an extruder for melting, extruding from a T-shaped die head of a casting machine, uniformly blowing up by a gas knife and adhering to a casting cooling roller to obtain an extruded blank film;

[0039] wherein the melting temperature is 350℃, the lip gap of the die head is 0.05mm, the extrusion temperature of the die head is 370℃, and the gas pressure of the gas knife is 0.3MPa;

[0040] (3) calendering and cooling forming: shaping the obtained extruded blank film by a cooling roller to obtain a FEP film;

[0041] wherein the cooling roller is cooled by conducting heat transfer oil, and the temperature of the cooling roller is controlled at 150℃ after passing through an internal cooling and heating exchanger of the cooling roller, and the rotating speed of the cooling roller is 5m / min;

[0042] (4) traction flattening, edge cutting and winding: after the obtained FEP film is subjected to traction flattening, edge cutting and winding, the FEP cast film is obtained.

[0043] The edge material generated in the edge cutting process of step (3) of the above preparation example 1 is defined as FEP cast film edge material with recycling times of 1, and is denoted as F1.

[0044] Example 1

[0045] A recycling method of FEP cast film edge material, specifically comprising the following steps:

[0046] (1) granulation: granulating the FEP cast film edge material F1 (from preparation example 1) by a single screw granulator to obtain recycled material particles;

[0047] wherein the length-diameter ratio of the single screw granulator is 1:22, and the temperature from the feeding port to each zone is in turn: the feeding port (220℃), zone 1 (250℃), zone 2 (270℃), zone 3 (270℃), zone 4 (270℃), the length of each zone is 10cm, the temperature of the screen changer is 270℃, the filter screen is five layers of filter, stacked according to 80 mesh / 80 mesh / 100 mesh / 100 mesh / 120 mesh, the temperature of the die head is 270℃, and during the granulation process, the total heating time from feeding to discharging needs to be controlled at 70s, the compressed air is turned on, the die head rotation is turned on, and the rotating speed of the cutter is adjusted according to the size of the particles, and the rotating speed of the cutter is not less than 25Hz;

[0048] (2) blending: blending the recycled material particles with a mass percentage of 30%, FEP resin A with a mass percentage of 65%, and color masterbatch with a mass percentage of 5% to obtain a blended raw material;

[0049] (3) melt extrusion: adding the obtained blended raw material into an extruder for melting, extruding from a T-shaped die of a casting machine, uniformly blowing up by a gas knife and adhering to a casting cooling roller to obtain an extruded blank film;

[0050] wherein the melting temperature is 350°C, the lip gap of the die is 0.05 mm, the extrusion temperature of the die is 370°C, and the gas pressure of the gas knife is 0.3 MPa;

[0051] (4) calendering and cooling forming: shaping the obtained extruded blank film by a cooling roller to obtain a FEP film;

[0052] wherein the cooling roller is cooled by conducting heat transfer oil, and the temperature of the cooling roller is controlled at 150°C after passing through an internal cooling heat exchanger of the cooling roller, and the rotating speed of the cooling roller is 5 m / min;

[0053] (5) traction flattening and edge cutting and winding: after the obtained FEP film is subjected to traction flattening and edge cutting and winding, a recycled FEP casting film is obtained, and the recycling of the FEP casting film edge material is completed.

[0054] The edge material produced in the edge cutting process of step (5) of the above-mentioned embodiment 1 is defined as FEP casting film edge material with a recycling number of 2 times, denoted as F2.

[0055] Embodiment 2

[0056] A recycling method of FEP casting film edge material, which is different from embodiment 1 in that FEP casting film edge material F2 from embodiment 1 is used to replace FEP casting film edge material F1 from preparation example 1, and other substances, amounts, steps and parameters are the same as those of embodiment 1.

[0057] The edge material produced in the edge cutting process of the above-mentioned embodiment 2 is defined as FEP casting film edge material with a recycling number of 3 times, denoted as F3.

[0058] Embodiment 3

[0059] A recycling method of FEP casting film edge material, which is different from embodiment 1 in that FEP casting film edge material F3 from embodiment 2 is used to replace FEP casting film edge material F1 from preparation example 1, and other substances, amounts, steps and parameters are the same as those of embodiment 1.

[0060] The edge material produced in the edge cutting process of the above-mentioned embodiment 3 is defined as FEP casting film edge material with a recycling number of 4 times, denoted as F4.

[0061] Example 4

[0062] A recycling method of FEP cast film edge material, which is different from Example 1 in that FEP cast film edge material F4 from Example 3 is used to replace FEP cast film edge material F1 from Preparation Example 1, and other substances, amounts, steps and parameters are the same as those in Example 1.

[0063] The edge material generated in the trimming process in Example 4 above is defined as FEP cast film edge material with 5 times of recycling, denoted as F5.

[0064] Example 5

[0065] A recycling method of FEP cast film edge material, which is different from Example 1 in that FEP cast film edge material F5 from Example 4 is used to replace FEP cast film edge material F1 from Preparation Example 1, and other substances, amounts, steps and parameters are the same as those in Example 1.

[0066] Example 6

[0067] A recycling method of FEP cast film edge material, which is different from Example 1 only in that FEP resin B is used to replace FEP resin A, and other substances, amounts, steps and parameters are the same as those in Example 1.

[0068] Example 7

[0069] A recycling method of FEP cast film edge material, which is different from Example 1 only in that the mass percentage of recycled material particles is 40%, and the mass percentage of FEP resin A is 55%, and other substances, amounts, steps and parameters are the same as those in Example 1.

[0070] Example 8

[0071] A recycling method of FEP cast film edge material, which is different from Example 1 only in that the mass percentage of recycled material particles is 45%, and the mass percentage of FEP resin A is 50%, and other substances, amounts, steps and parameters are the same as those in Example 1.

[0072] Comparative Example 1

[0073] A recycling method of FEP cast film edge material, which is different from Example 1 only in that the mass percentage of recycled material particles is 95%, and the mass percentage of FEP resin A is 0%, and other substances, amounts, steps and parameters are the same as those in Example 1.

[0074] Performance test:

[0075] (1) Tensile strength and elongation at break: tested according to the method provided in ASTM D 882-10;

[0076] (2) Piercing force: tested according to the method provided in ASTM F1306-16.

[0077] The FEP casting films prepared from Preparation Example 1, Examples 1-8 and Comparative Example 1 were tested according to the above test methods, and the test results are shown in Table 1:

[0078] Table 1

[0079]

[0080]

[0081] According to the data in Table 1, it can be seen that:

[0082] (1) The recycling method provided by the present application can realize recycling of FEP casting film edge material, and the tensile properties and piercing resistance of the obtained recycled FEP casting film are still good after at least five cycles of recycling.

[0083] (2) Since granulation and casting film formation are carried out by melt extrusion, partial decomposition of raw materials may occur in a high temperature environment, so the proportion of recycled material particles should not be too high, otherwise the performance of the recycled FEP casting film will be reduced, and if the proportion is too low, the amount of edge material produced will be greater than the recycled material particles recycled, which is not meaningful for actual production.

[0084] The applicant declares that the present application illustrates a recycling method for FEP casting film edge material, recycled FEP casting film and its application by the above examples, but the present application is not limited to the above examples, that is, it does not mean that the present application must rely on the above examples to be implemented. Those skilled in the art should understand that any improvement on the present application, equivalent replacement of each raw material of the product of the present application, addition of auxiliary ingredients, selection of specific methods, etc. fall within the scope of protection and disclosure of the present application.

Claims

1. A method for recycling FEP cast film scrap, characterized by, The FEP casting film is prepared by the following method, which comprises the following steps: The FEP resin with a mass percentage of 95% and the color masterbatch with a mass percentage of 5% are blended to obtain a blended raw material, and then the blended raw material is melt-extruded, calendered and cooled, stretched, cut and wound to obtain the FEP casting film. The recycling method of the FEP casting film edge material comprises the following steps: (1) Granulation: The FEP casting film edge material is granulated to obtain recycled material particles; (2) Blending: The recycled material particles obtained in step (1), FEP resin and color masterbatch are blended to obtain a blended raw material; (3) Film production: The blended raw material obtained in step (2) is melt-extruded, calendered and cooled, stretched, cut and wound to obtain a recycled FEP casting film, thereby completing the recycling of the FEP casting film edge material; The FEP casting film edge material comprises: The FEP casting film edge material produced in the cutting process by using FEP casting film edge material with a recycling number of less than or equal to 5 times, FEP resin and color masterbatch as a blended raw material, the mass percentage of the recycled material particles is 30%, the mass percentage of the FEP resin is 65%, and the mass percentage of the color masterbatch is 5%; The FEP casting film edge material produced in the cutting process by using FEP casting film edge material with a recycling number of less than or equal to 5 times, FEP resin and color masterbatch as a blended raw material, the mass percentage of the recycled material particles is 30%, the mass percentage of the FEP resin is 65%, and the mass percentage of the color masterbatch is 5%; 2. The recycling method according to claim 1, characterized in that, The FEP casting film edge material produced in the cutting process by using FEP casting film edge material with a recycling number of less than or equal to 5 times, FEP resin and color masterbatch as a blended raw material, the mass percentage of the recycled material particles is 30%, the mass percentage of the FEP resin is 65%, and the mass percentage of the color masterbatch is 5%; 3. The recycling method according to claim 1, characterized in that, The granulation in step (1) is performed in a single-screw granulator.

4. The recycling method according to claim 3, characterized in that, The length-diameter ratio of the single screw of the single-screw granulator is above 1:20, and the temperature from the feeding port to each zone is in turn: 200-400℃ for the feeding port, 200-400℃ for zone 1, 200-400℃ for zone 2, 200-400℃ for zone 3, 200-400℃ for zone 4, the length of each zone is independently 10-20 cm, the temperature of the screen changer is 250-370℃, the filter screen is at least three layers, and the precision of each layer is at least 80 mesh, and the temperature of the die head is 250-370℃.

5. The recycling method according to claim 1, characterized in that, In the granulation process of step (1), the total heating time from feeding to discharging is controlled to be 30-180 s, the cold-blowing compressed air is turned on, the die head rotation is turned on, the rotation speed of the cutter is adjusted according to the size of the particles, and the rotation speed of the cutter is not less than 25 Hz.

6. The recycling method of claim 1, wherein, The melt index of the FEP resin in step (2) is 1-20 g / 10min.

7. The recycling method according to claim 1, characterized by, The melt extrusion process of step (3) specifically comprises: feeding the blended raw material obtained in step (2) into an extruder for melting, extruding through a T-shaped die of a casting machine, uniformly blowing up by a gas knife to adhere to a casting cooling roller, obtaining an extruded blank film, and completing the melt extrusion.

8. The recycling method of claim 1, wherein, The temperature of the melting is 330-380℃, the lip gap of the die is 0.02-0.07 mm, the extrusion temperature of the die is 350-380℃, and the gas pressure of the gas knife is 0.2-0.7 MPa.

9. The recycling method of claim 1, wherein, The calender cooling molding process of step (3) specifically comprises: shaping the extruded blank film obtained by melt extrusion through a cooling roller to obtain a FEP film.

10. The recycling method according to claim 9, characterized in that, The cooling roller is cooled by conducting heat transfer oil, and the temperature of the cooling roller is controlled at 120-180℃ after passing through an internal cooling heat exchanger of the cooling roller, and the rotating speed of the cooling roller is 1-10 m / min.

11. A recycled FEP cast film characterized in that, The recycled FEP casting film is prepared by using the recycling method according to any one of claims 1-10.

12. The recycled FEP cast film of claim 11, wherein, The tensile strength of the recycled FEP casting film in the MD direction is not less than 43 MPa, and the tensile strength in the TD direction is not less than 37 MPa.

13. Use of the recycled FEP casting film according to claim 11 or 12 in a composite material forming process.

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