Drying method of fluorinated ethylene propylene color master batch

Abstract

The invention belongs to the technical field of fluorinated ethylene propylene, and particularly relates to a fluorinated ethylene propylene color master batch drying method which comprises the following steps: standing a fluorinated ethylene propylene raw material at low temperature for 20-30 minutes, and then freezing and grinding to obtain fluorinated ethylene propylene refined particles; the fluorinated ethylene propylene refined particles are put into a reaction kettle to be frozen and dried, then soaked into a polyvinylpyrrolidone solution to be subjected to ultrasonic dispersion for 20-40 min, filtered and dried, and coated particles are obtained; the coated particles are put into a reaction kettle to be subjected to constant-temperature negative-pressure standing for 2-3 h, and prefabricated particles are obtained after nitrogen purging; the prefabricated particles are put into ethyl alcohol to be subjected to ultrasonic treatment for 20-30 min, after filtration, ethyl alcohol washing is conducted for 2-3 times, drying is conducted, and the dried fluorinated ethylene propylene color master batch is obtained. The problems that fluorinated ethylene propylene is high in water content and low in drying efficiency are solved, exposed water is removed in the mode that low-temperature freezing grinding is matched with freezing drying, the internal and external pressure difference is formed in the constant-temperature negative-pressure mode, and therefore the effect of releasing water vapor is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of poly(perfluoroethylene propylene), and in particular relates to a method for drying poly(perfluoroethylene propylene) masterbatch. Background Art

[0002] FEP is a modified derivative of polytetrafluoroethylene (PTFE). Its heat resistance is inferior to that of PTFE, but it can operate for long periods at high temperatures and possesses the excellent processability of thermoplastics, making up for the difficulty in processing PTFE. However, the moisture content of the FEP raw material is around 30%, and moisture can cause the FEP material to swell and even reduce its mechanical properties. Moisture also accelerates the aging process of the FEP, leading to decreased material performance and a shortened service life. Current FEP processes use high-temperature drying or melting to remove moisture, which not only wastes energy and is inefficient, but also results in high costs and difficulty in industrial implementation. Summary of the Invention

[0003] In response to the problems in the prior art, the present invention provides a drying method for polyperfluoroethylene propylene (FEP) masterbatch, which solves the problems of high water content and low drying efficiency of FEP. The method uses low-temperature freezing grinding combined with freeze drying to remove exposed moisture, and uses a constant temperature and negative pressure method to form an internal and external pressure difference to achieve the effect of water vapor release. Polyvinyl pyrrolidone is used to fix water molecules, thereby achieving the drying treatment of the material.

[0004] In order to achieve the above technical objectives, the technical solution of the present invention is: A method for drying poly(perfluoroethylene propylene) masterbatch, comprising the following steps: Step 1: allowing a poly(perfluoroethylene propylene) raw material to stand at a low temperature for 20-30 minutes, and then freeze-grinding to obtain poly(perfluoroethylene propylene) refined particles. The poly(perfluoroethylene propylene) raw material is a water-containing poly(perfluoroethylene propylene) masterbatch. The low-temperature standing atmosphere is a nitrogen atmosphere at a temperature of 0-5°C, the freeze-grinding temperature is -25°C, and the grinding pressure is 0.9-1.4 MPa. This step utilizes low-temperature standing under a nitrogen atmosphere to ensure internal and external temperature consistency, and utilizes freezing to convert the moisture of the raw material into a solid ice state. Combined with the grinding and refining effect, the poly(perfluoroethylene propylene) raw material is granulated without causing structural damage. Step 2: freeze-dry the refined fluoroethylene propylene particles in a reactor, then immerse them in a polyvinyl pyrrolidone solution and ultrasonically disperse them for 20-40 minutes, filter and dry them to obtain coated particles; the freeze-drying temperature is -25°C; the polyvinyl pyrrolidone solution uses a polyvinyl pyrrolidone ethanol solution with a concentration of 100-400 g / L, the concentration of the refined fluoroethylene propylene particles in the polyvinyl pyrrolidone solution is 100-200 g / L, the ultrasonic dispersion temperature is 10-20°C, and the ultrasonic frequency is 70-90 kHz, and the drying temperature is 80-90°C; this step utilizes the low particle size and high exposed area of ​​the refined particles themselves, combined with freeze-drying to remove surface exposed moisture; utilizing the solubility and dispersibility of polyvinyl pyrrolidone in ethanol, a surface liquid film is formed on the surface of the polyvinyl pyrrolidone refined particles, and the ethanol is removed by drying, thereby forming a coated particle structure in which the polyvinyl pyrrolidone wraps the polyperfluoroethylene propylene refined particles, and the polyvinyl pyrrolidone is converted from a liquid film to a solid film, which can completely occupy the pore structure generated by the removal of surface moisture; Step 3: Place the coated particles in a reactor and place them under constant temperature and negative pressure for 2-3 hours. After nitrogen purging, prefabricated particles are obtained. The constant temperature and negative pressure temperature is 110-120°C and the pressure is 3.6-4kPa. The nitrogen purging temperature is 100-110°C and the speed is 5-10mL / min. This step uses constant temperature and negative pressure to convert the internal moisture into water vapor. At the same time, the external negative pressure is used to form an internal and external pressure difference, thereby enhancing the destructive effect of the steam and ultimately directly removing the water vapor. The polyvinyl pyrrolidone coated on the surface can form a certain adsorption capacity for water vapor, thereby achieving the effect of dispersion and solidification. The nitrogen purging can expel water vapor in the air and balance the internal pressure. Step 4: placing the prefabricated particles in ethanol for ultrasonic treatment for 20-30 minutes, filtering, washing with ethanol 2-3 times, and drying to obtain dry polyperfluoroethylene propylene masterbatch, wherein the mass ratio of the prefabricated particles to ethanol is 1:5-10, the ultrasonic frequency of the ultrasonic treatment is 80-100 kHz, the temperature is 5-10°C; and the drying temperature is 80-90°C. This step utilizes the solubility of polyvinyl pyrrolidone in ethanol and the miscibility of water and ethanol to directly dissolve the aqueous polyvinyl pyrrolidone on the surface of the polyperfluoroethylene propylene in ethanol to form a solution, and cooperates with the washing effect of ethanol to obtain a relatively clean polyperfluoroethylene propylene masterbatch. The ethanol is removed by drying to obtain a dry polyperfluoroethylene propylene masterbatch. It can be seen from the above description that the present invention has the following advantages: 1. The present invention solves the problems of high water content and low drying efficiency of FEP by removing exposed moisture through low-temperature freezing and grinding combined with freeze drying. A constant temperature and negative pressure method is used to create an internal and external pressure difference, thereby achieving the effect of water vapor release. Polyvinylpyrrolidone is used to fix water molecules, thereby achieving the drying process of the material.

[0005] 2. The present invention utilizes low temperature and freezing treatment to effectively reduce the effect of temperature on polyperfluoroethylene propylene, and also reduces energy consumption and processing costs. DETAILED DESCRIPTION

[0006] The present invention is described in detail with reference to the embodiments, but no limitation is imposed on the claims of the present invention. Example

[0007] A method for drying poly(perfluoroethylene propylene) masterbatch, comprising the following steps: Step 1: allowing a poly(perfluoroethylene propylene) raw material to stand at a low temperature for 20 minutes, and then freeze-grinding to obtain poly(perfluoroethylene propylene) refined particles, wherein the poly(perfluoroethylene propylene) raw material is a water-containing poly(perfluoroethylene propylene) masterbatch; the atmosphere for the low-temperature standing is a nitrogen atmosphere at a temperature of 0° C., the temperature for the freeze-grinding is −25° C., and the grinding pressure is 0.9 MPa; Step 2: freeze-drying the refined fluoroethylene propylene particles in a reactor, then immersing them in a polyvinyl pyrrolidone solution and ultrasonically dispersing them for 20 minutes, filtering them, and drying them to obtain coated particles; the freeze-drying temperature is -25°C; the polyvinyl pyrrolidone solution uses a polyvinyl pyrrolidone ethanol solution with a concentration of 100 g / L, the concentration of the refined fluoroethylene propylene particles in the polyvinyl pyrrolidone solution is 100-200 g / L, the ultrasonic dispersion temperature is 10°C, the ultrasonic frequency is 70 kHz, and the drying temperature is 80°C; Step 3: Place the coated particles in a reactor and place them under constant temperature and negative pressure for 2 hours. Purge with nitrogen to obtain prefabricated particles. The constant temperature and negative pressure temperature is 110° C. and the pressure is 3.6 kPa. The nitrogen purge temperature is 100° C. and the speed is 5 mL / min. Step 4: Place the prefabricated particles in ethanol and ultrasonically treat for 20 minutes, filter and wash with ethanol twice, and dry to obtain dry polyperfluoroethylene propylene masterbatch, wherein the mass ratio of the prefabricated particles to ethanol is 1:5, the ultrasonic frequency of the ultrasonic treatment is 80 kHz, and the temperature is 5°C; the drying temperature is 80°C.

[0008] The initial moisture content of the polyperfluoroethylene propylene in this embodiment is 23%, the drying rate reaches 99.95%, and the polyvinyl pyrrolidone is recyclable. The recovery rate after 30 practical uses reaches 99.2%. The obtained polyperfluoroethylene propylene has a small particle size and high surface roughness. Example

[0009] A method for drying poly(perfluoroethylene propylene) masterbatch, comprising the following steps: Step 1: allowing a poly(perfluoroethylene propylene) raw material to stand at a low temperature for 30 minutes, and then freeze-grinding to obtain poly(perfluoroethylene propylene) refined particles, wherein the poly(perfluoroethylene propylene) raw material is a water-containing poly(perfluoroethylene propylene) masterbatch; the atmosphere for the low-temperature standing is a nitrogen atmosphere at a temperature of 5° C., the freeze-grinding temperature is −25° C., and the grinding pressure is 1.4 MPa; Step 2: freeze-drying the refined fluoroethylene propylene particles in a reactor, then immersing them in a polyvinyl pyrrolidone solution and ultrasonically dispersing them for 40 minutes, filtering them, and drying them to obtain coated particles; the freeze-drying temperature is -25°C; the polyvinyl pyrrolidone solution uses a polyvinyl pyrrolidone ethanol solution with a concentration of 400 g / L, the concentration of the refined fluoroethylene propylene particles in the polyvinyl pyrrolidone solution is 200 g / L, the ultrasonic dispersion temperature is 20°C, the ultrasonic frequency is 90 kHz, and the drying temperature is 90°C; Step 3: placing the coated particles in a reactor at a constant temperature and negative pressure for 3 hours, and purging with nitrogen to obtain prefabricated particles. The constant temperature and negative pressure temperature is 120° C. and the pressure is 4 kPa. The nitrogen purge temperature is 110° C. and the speed is 10 mL / min. Step 4: The prefabricated particles are placed in ethanol and ultrasonically treated for 30 minutes. After filtering, the particles are washed with ethanol three times and dried to obtain dry polyperfluoroethylene propylene masterbatch. The mass ratio of the prefabricated particles to ethanol is 1:10. The ultrasonic frequency of the ultrasonic treatment is 100 kHz and the temperature is 10°C. The drying temperature is 90°C.

[0010] The initial moisture content of the polyperfluoroethylene propylene in this embodiment is 25%, the drying rate reaches 99.96%, and the polyvinyl pyrrolidone is recyclable. The recovery rate after 30 practical uses reaches 99.4%. The obtained polyperfluoroethylene propylene has a small particle size and high surface roughness. Example

[0011] A method for drying poly(perfluoroethylene propylene) masterbatch, comprising the following steps: Step 1: allowing a poly(perfluoroethylene propylene) raw material to stand at a low temperature for 25 minutes, and then freeze-grinding to obtain poly(perfluoroethylene propylene) refined particles, wherein the poly(perfluoroethylene propylene) raw material is a water-containing poly(perfluoroethylene propylene) masterbatch; the atmosphere for the low-temperature standing is a nitrogen atmosphere at a temperature of 2° C., the freeze-grinding temperature is −25° C., and the grinding pressure is 1.2 MPa; Step 2: freeze-drying the refined fluoroethylene propylene particles in a reactor, then immersing them in a polyvinyl pyrrolidone solution and ultrasonically dispersing them for 25 minutes, filtering them, and drying them to obtain coated particles; the freeze-drying temperature is -25°C; the polyvinyl pyrrolidone solution uses a polyvinyl pyrrolidone ethanol solution with a concentration of 200 g / L, the concentration of the refined fluoroethylene propylene particles in the polyvinyl pyrrolidone solution is 130 g / L, the ultrasonic dispersion temperature is 15°C, the ultrasonic frequency is 80 kHz, and the drying temperature is 85°C; Step 3: placing the coated particles in a reactor at a constant temperature and negative pressure for 2 hours, and purging with nitrogen to obtain prefabricated particles. The constant temperature and negative pressure temperature is 115° C. and the pressure is 3.6 kPa. The nitrogen purge temperature is 105° C. and the speed is 7 mL / min. Step 4: Place the prefabricated particles in ethanol and ultrasonically treat them for 25 minutes. After filtering, wash them with ethanol three times and dry them to obtain dry polyperfluoroethylene propylene masterbatch. The mass ratio of the prefabricated particles to ethanol is 1:6. The ultrasonic frequency of the ultrasonic treatment is 90 kHz and the temperature is 6°C. The drying temperature is 85°C.

[0012] The initial moisture content of the polyperfluoroethylene propylene of this embodiment is 22%, the drying rate reaches 99.94%, and the polyvinyl pyrrolidone is recyclable. The recovery rate after 30 practical uses reaches 99.3%. The obtained polyperfluoroethylene propylene has a small particle size and high surface roughness. Example

[0013] A method for drying poly(perfluoroethylene propylene) masterbatch, comprising the following steps: Step 1: allowing a poly(perfluoroethylene propylene) raw material to stand at a low temperature for 28 minutes, and then freeze-grinding to obtain poly(perfluoroethylene propylene) refined particles, wherein the poly(perfluoroethylene propylene) raw material is a water-containing poly(perfluoroethylene propylene) masterbatch; the atmosphere for the low-temperature standing is a nitrogen atmosphere at a temperature of 4° C., the freeze-grinding temperature is −25° C., and the grinding pressure is 1.1 MPa; Step 2: freeze-drying the refined fluoroethylene propylene particles in a reactor, then immersing them in a polyvinyl pyrrolidone solution and ultrasonically dispersing them for 30 minutes, filtering them, and drying them to obtain coated particles; the freeze-drying temperature is -25°C; the polyvinyl pyrrolidone solution uses a polyvinyl pyrrolidone ethanol solution with a concentration of 300 g / L, the concentration of the refined fluoroethylene propylene particles in the polyvinyl pyrrolidone solution is 120 g / L, the ultrasonic dispersion temperature is 18°C, the ultrasonic frequency is 80 kHz, and the drying temperature is 85°C; Step 3: placing the coated particles in a reactor at a constant temperature and negative pressure for 3 hours, and purging with nitrogen to obtain prefabricated particles. The constant temperature and negative pressure temperature is 118° C. and the pressure is 4 kPa. The nitrogen purge temperature is 108° C. and the speed is 8 mL / min. Step 4: The prefabricated particles are placed in ethanol and ultrasonically treated for 25 minutes. After filtering, the particles are washed with ethanol twice and dried to obtain dry polyperfluoroethylene propylene masterbatch. The mass ratio of the prefabricated particles to ethanol is 1:8. The ultrasonic frequency of the ultrasonic treatment is 90 kHz and the temperature is 8°C. The drying temperature is 85°C.

[0014] The initial moisture content of the polyperfluoroethylene propylene of this embodiment is 22%, the drying rate reaches 99.96%, and the polyvinyl pyrrolidone is recyclable. The recovery rate after 30 practical uses reaches 99.3%. The obtained polyperfluoroethylene propylene has a small particle size and high surface roughness.

[0015] The drying rates of the above embodiments 1-4 are much higher than the current mechanical water removal process, and the process is simple, the energy consumption is low, and some raw materials can be efficiently recycled and reused, which complies with the relevant regulations on energy conservation and emission reduction. It is understood that the above specific description of the present invention is only used to illustrate the present invention and is not limited to the technical solutions described in the embodiments of the present invention. Those skilled in the art should understand that the present invention can still be modified or replaced with equivalents to achieve the same technical effects; as long as the use requirements are met, they are all within the scope of protection of the present invention.

Claims

1. A method for drying poly(perfluoroethylene propylene) masterbatch, characterized in that : Includes the following steps: Step 1: allowing the polyperfluoroethylene propylene raw material to stand at low temperature for 20-30 minutes, and then freeze-grinding to obtain polyperfluoroethylene propylene fine particles; Step 2: placing the refined fluoroethylene propylene particles into a reactor and freeze-drying them, then immersing them in a polyvinyl pyrrolidone solution and ultrasonically dispersing them for 20-40 minutes, filtering them, and drying them to obtain coated particles; Step 3: Place the coated particles in a reactor and place them under constant temperature and negative pressure for 2-3 hours, and then purge with nitrogen to obtain prefabricated particles; Step 4: placing the prefabricated particles in ethanol and ultrasonically treating them for 20-30 minutes, filtering them, washing them with ethanol for 2-3 times, and drying them to obtain dry polyperfluoroethylene propylene masterbatch.

2. The drying method of poly(perfluoroethylene propylene) masterbatch according to claim 1, characterized in that : The polyperfluoroethylene propylene raw material in step 1 is water-containing polyperfluoroethylene propylene masterbatch.

3. The drying method of poly(perfluoroethylene propylene) masterbatch according to claim 1, characterized in that : The low-temperature standing atmosphere in the step 1 is a nitrogen atmosphere with a temperature of 0-5°C, the temperature of the frozen grinding is -25°C, and the grinding pressure is 0.9-1.4MPa.

4. The drying method of poly(perfluoroethylene propylene) masterbatch according to claim 1, characterized in that : The freeze-drying temperature in step 2 is -25°C; the polyvinyl pyrrolidone solution adopts a polyvinyl pyrrolidone ethanol solution with a concentration of 100-400g / L, and the concentration of the polyperfluoroethylene propylene fine particles in the polyvinyl pyrrolidone solution is 100-200g / L.

5. The drying method of poly(perfluoroethylene propylene) masterbatch according to claim 1, characterized in that : The temperature of the ultrasonic dispersion in step 2 is 10-20°C, the ultrasonic frequency is 70-90kHz, and the temperature of the drying is 80-90°C.

6. The drying method of poly(perfluoroethylene propylene) masterbatch according to claim 1, characterized in that : The constant temperature and negative pressure standing temperature in step 3 is 110-120°C, the pressure is 3.6-4kPa, and the nitrogen purge temperature is 100-110°C, and the speed is 5-10mL / min.

7. The drying method of poly(perfluoroethylene propylene) masterbatch according to claim 1, characterized in that : In step 4, the mass ratio of the prefabricated particles to ethanol is 1:5-10, the ultrasonic frequency of the ultrasonic treatment is 80-100 kHz, and the temperature is 5-10°C.

8. The drying method of poly(perfluoroethylene propylene) masterbatch according to claim 1, characterized in that : The drying temperature in step 4 is 80-90°C.