FEP resin and preparation method thereof
By using ammonium perfluorobutyl sulfonate emulsifier and composite chain transfer agent, combined with molecular sieve and adsorbent purification, the problems of emulsifier residue and uneven molecular weight distribution in FEP resin preparation were solved, achieving improvements in environmental compliance and performance consistency.
Patent Information
- Application Number
- CN202511491830.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-20
- Publication Date
- 2026-01-20
AI Technical Summary
In the current preparation of FEP resin, emulsifiers are difficult to degrade in an environmentally friendly manner and have uneven molecular weight distribution, which affects product performance and environmental compliance.
Ammonium perfluorobutylsulfonate was used as an emulsifier, and the monomer was purified by molecular sieves and adsorbents. Combined with treatment with composite chain transfer agents and electrolyte solutions, efficient dispersion and molecular weight control of the monomer were achieved.
It reduces emulsifier residue, improves the consistency of product mechanical properties and environmental compliance, and enhances the stability of the processing and the uniformity of molded products.
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Figure SMS_1
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of polyfluoroethylene propylene resin, in particular to a FEP resin and a preparation method thereof. BACKGROUND
[0002] In the emulsion polymerization preparation process of FEP resin, the auxiliary control system has long been faced with two interrelated technical problems, which restrict the synergistic improvement of product performance and environmental performance. Traditional processes generally rely on fluorine-containing emulsifiers to maintain emulsion stability. Although such substances can effectively disperse monomers and promote polymerization, they are difficult to degrade in the natural environment due to their strong chemical stability, and are easy to accumulate through the food chain and cause potential harm to organisms. In order to meet the increasingly stringent environmental regulations, the residual emulsifier needs to be removed after polymerization. However, existing physical or chemical treatment methods are either inefficient or can damage the stability of the emulsion system, leading to a prominent contradiction between environmental compliance and process stability.
[0003] At the same time, precise control of molecular weight distribution has always been a core challenge in FEP preparation. Existing technologies mostly use a single chain transfer agent to regulate molecular chain growth, but its effect is easily affected by the dynamic changes of the polymerization system. As the reaction proceeds, the increased viscosity of the polymer particles will hinder the mass transfer efficiency of the chain transfer agent between the water phase and the particle phase, resulting in uneven local concentration and ultimately forming a wide distribution of molecular weight structure. This structural defect will reduce the consistency of the mechanical properties of the product.
[0004] Based on this, the present application designs a FEP resin and a preparation method thereof to solve the above problems. SUMMARY
[0005] In view of the above-mentioned shortcomings of the prior art, the present application provides a FEP resin and a preparation method thereof.
[0006] To achieve the above purpose, the present application realizes the following technical scheme: A preparation method of a FEP resin, comprising the following steps: S1: Purification of tetrafluoroethylene monomer, the tetrafluoroethylene monomer is introduced into a dehydration tower filled with molecular sieves for dehydration treatment, and after dehydration, it is introduced into an adsorption tower filled with modified activated carbon to remove impurities; S2: Purification of hexafluoropropylene monomer, the hexafluoropropylene monomer is introduced into a dehydration tower filled with molecular sieves for dehydration treatment, and after dehydration, it is introduced into an adsorption tower filled with activated alumina to remove impurities; S3: Preparation of monomer mixture A, under a nitrogen atmosphere, the purified tetrafluoroethylene and the purified hexafluoropropylene are introduced into a mixing container at a molar ratio of 14-20:80-86 simultaneously, and after the introduction is completed, the monomer mixture A is obtained by stirring; S4: Preparation of monomer mixture B, under a nitrogen atmosphere, purified tetrafluoroethylene and purified hexafluoropropylene were simultaneously introduced into a mixing container at a molar ratio of 85-92:8-15, and after the introduction was completed, stirring was started to obtain monomer mixture B; S5: The emulsifier ammonium perfluorobutyl sulfonate was weighed, the amount was 0.05-0.5% of the total monomer weight of purified tetrafluoroethylene and purified hexafluoropropylene; the initiator cyclohexyl hydroperoxide was weighed, the amount was 0.01-0.1% of the total monomer weight of purified tetrafluoroethylene and purified hexafluoropropylene; a composite chain transfer agent was prepared by mixing methane and ethanol at a molar ratio of 1:2-3, the total amount was 0.1-1% of the total monomer weight of purified tetrafluoroethylene and purified hexafluoropropylene; S6: Deionized water was added to the polymerization reactor, and the emulsifier ammonium perfluorobutyl sulfonate was added to the deionized water and stirred until completely dissolved; The reactor was sealed and vacuumed, the monomer mixture A was placed in the sealed reactor, the initiator was added to start the polymerization, and the monomer mixture B was continuously added in multiple times during the reaction, and the composite chain transfer agent was added to obtain the FEP emulsion; S7: An electrolyte solution was added to the FEP emulsion, stirring was performed for demulsification treatment, centrifugation was performed to obtain polymer particles, the polymer particles were washed with deionized water for multiple times, the washed polymer particles were dried, and the dried polymer particles were extruded and granulated to obtain the FEP resin.
[0007] Further, S1 is specifically: the tetrafluoroethylene monomer is introduced into a dehydration tower filled with 10-30 mesh 4A molecular sieves for dehydration treatment, the dehydration temperature is 20-30℃, and the pressure is 0.1-0.2 MPa; after dehydration, the impurities are removed by adsorption into an adsorption tower filled with 10-30 mesh modified activated carbon, the adsorption temperature is 20-30℃, and the pressure is 0.1-0.2 MPa.
[0008] Further, the preparation method of the modified activated carbon is: triethylenetetramine is weighed at 5-12% of the mass of the activated carbon, dissolved in deionized water, the activated carbon is added to the solution at a solid-liquid ratio of 1:10-15, stirred at 30-60℃ and 300-500 r / min for 5-8 h; and the modified activated carbon is obtained by centrifugation.
[0009] Further, S2 is specifically: the hexafluoropropylene monomer is introduced into a dehydration tower filled with 10-30 mesh 3A molecular sieves for dehydration treatment, the dehydration temperature is 20-30℃, and the pressure is 0.1-0.2 MPa; after dehydration, the impurities are removed by adsorption into an adsorption tower filled with 10-30 mesh activated alumina, the adsorption temperature is 20-30℃, and the pressure is 0.1-0.2 MPa.
[0010] Further, S3 is specifically: a closed mixing container with stirring device is selected, the container is first dried, then dry nitrogen is introduced for replacement, the nitrogen flow rate is controlled to be 5-10 L / min, the replacement is performed for 20-40 min, the purified tetrafluoroethylene and the purified hexafluoropropylene are introduced into the mixing container at a molar ratio of 14-20:80-86 and a flow rate controlled by a mass flow meter, the purified tetrafluoroethylene monomer is introduced at a flow rate of 0.5-2 kg / h, the purified hexafluoropropylene monomer is introduced at a flow rate of 2-5 kg / h, the stirring device is started after the introduction is completed, the stirring speed is 150-300 r / min, the stirring is performed for 15-30 min, the pressure is 0.1-0.2 MPa, and a monomer mixture A is obtained.
[0011] Further, S4 is specifically: another closed mixing container with stirring device is selected, the container is first dried, then dry nitrogen is introduced for replacement, the nitrogen flow rate is controlled to be 5-10 L / min, the replacement is performed for 20-40 min, the purified tetrafluoroethylene and the purified hexafluoropropylene are introduced into the mixing container at a molar ratio of 85-92:8-15 and a flow rate controlled by a mass flow meter, the purified tetrafluoroethylene monomer is introduced at a flow rate of 2-6 kg / h, the purified hexafluoropropylene monomer is introduced at a flow rate of 0.2-1 kg / h, the stirring device is started after the introduction is completed, the stirring speed is 150-300 r / min, the stirring is performed for 15-30 min, the pressure is 0.1-0.2 MPa, and a monomer mixture B is obtained.
[0012] Further, S6 is specifically: deionized water is added to a polymerization reactor, the amount of the deionized water is 150-180% of the total monomer weight of the purified tetrafluoroethylene and the purified hexafluoropropylene, an emulsifier ammonium perfluorobutyl sulfonate is added to the deionized water, and stirring is performed at 200-400 r / min until complete dissolution; The monomer mixture A is placed in a sealed reactor at an initial absolute pressure of 1.1-1.5 MPa, the temperature is increased to 45-50 ℃, an initiator is added to start polymerization, the monomer mixture B is continuously added in 3-5 times during the reaction, each time interval is 30-60 min, a composite chain transfer agent is added, and the reaction is performed for 2-6 h to obtain a FEP emulsion. The mass ratio of the monomer mixture A to the monomer mixture B is 1:1.
[0013] Further, S7 is specifically: adding an electrolyte solution into the FEP emulsion, the electrolyte solution is a sodium sulfite solution with a concentration of 2-5 wt%, the amount of electrolyte solution is 2-5% of the volume of the FEP emulsion, demulsification treatment is carried out under stirring at 100-150 r / min, polymer particles are obtained by centrifugation, the polymer particles are washed with deionized water for 2-3 times, each washing time is 15-30 min, the washed polymer particles are dried at 130-140 DEG C for 5-7 h, and then the dried polymer particles are sent into an extrusion granulation device for extrusion granulation, the extrusion temperature is 340-360 DEG C, the pressure is 23-27 MPa, and the extrusion speed is 1.0-1.5 m / min, so as to obtain the FEP resin.
[0014] A FEP resin is prepared according to the preparation method of the FEP resin.
[0015] Compared with the prior art, the present application has the following beneficial effects: 1. In the present application, ammonium perfluorobutyl sulfonate is selected as an emulsifier, which has better compatibility with FEP monomers, can realize efficient dispersion of monomers at a lower dosage, avoids the problem of residual emulsifier caused by excessive emulsifier in traditional processes, and significantly reduces the impurity content after monomer purification, demulsification, multiple washing, dehydration of monomers by molecular sieves and removal of impurities by adsorbents, so that the emulsifier residue can be removed without relying on extreme physical or chemical means. The demulsification stage is controlled by a sodium sulfite solution, and the subsequent multiple deionized water washing and drying treatment further reduces the residue, which not only meets the requirements of environmental regulations on harmful residues, but also avoids the loss of control of polymer particle aggregation in the removal process, ensuring the stability of the polymerization system and the post-treatment process.
[0016] 2. In the present application, a composite chain transfer agent composed of methane and ethanol in a specific molar ratio is used, the mass transfer characteristics of the two components can adapt to the dynamic changes of the system viscosity in the polymerization process, improve the consistency of the mechanical properties of the product, significantly reduce the fluctuation of the copolymer composition, and thus improve the problem of flow fluctuation in the processing process and improve the performance uniformity of the molded product.
[0017] 3. In the present application, tetrafluoroethylene and hexafluoropropylene monomers are respectively dehydrated by a specific mesh molecular sieve and removed by a targeted adsorbent, which effectively removes water, hydrogen-containing impurities and other interference factors, and effectively improves the core mechanical properties such as tensile strength, bending strength and impact strength. DETAILED DESCRIPTION
[0018] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.
[0019] Embodiment 1: A preparation method of a FEP resin, characterized in that comprising the following steps: S1: tetrafluoroethylene monomer purification, the tetrafluoroethylene monomer is introduced into a dehydration tower provided with 10 mesh 4A molecular sieve for dehydration treatment, the dehydration temperature is 20 DEG C, the pressure is 0.1 MPa, after dehydration, the impurities are removed by being introduced into an adsorption tower filled with 10 mesh modified activated carbon, the adsorption temperature is 20 DEG C, the pressure is 0.1 MPa; The preparation method of the modified activated carbon is: According to 5% of the mass of the activated carbon, triethylene tetramine is weighed and dissolved in deionized water, the activated carbon is added to the solution according to a solid-liquid ratio of 1:10, and stirred at 30 DEG C and 300 r / min for 5 h; centrifugation is carried out at 8000 r / min for 15 min to obtain modified activated carbon; S2: hexafluoropropylene monomer purification, the hexafluoropropylene monomer is introduced into a dehydration tower provided with 10 mesh 3A molecular sieve for dehydration treatment, the dehydration temperature is 20 DEG C, the pressure is 0.1 MPa, after dehydration, the impurities are removed by being introduced into an adsorption tower filled with 10 mesh activated alumina, the adsorption temperature is 20 DEG C, the pressure is 0.1 MPa; S3: monomer mixture A preparation, a closed mixing container with a stirring device is selected, the container is first dried, then dry nitrogen is introduced for replacement, the nitrogen flow rate is controlled to be 5 L / min, the replacement is carried out for 20 min, the purified tetrafluoroethylene and the purified hexafluoropropylene are introduced into the mixing container at a molar ratio of 14:80 through mass flow meters to control the introduction rate, the introduction rate of the purified tetrafluoroethylene monomer is 0.5 kg / h, the introduction rate of the purified hexafluoropropylene monomer is 2 kg / h, the mixing container is introduced synchronously, after the introduction is completed, the stirring device is started, the rotating speed is 150 r / min, the stirring is carried out for 15 min, the pressure is 0.1 MPa, and monomer mixture A is obtained; S4: monomer mixture B preparation, select another closed mixing container with stirring device, first dry the container, then replace with dry nitrogen, control the nitrogen flow rate at 5 L / min, replace for 20 min, control the feeding rate of purified tetrafluoroethylene and purified hexafluoropropylene monomers through mass flow meters, the purified tetrafluoroethylene monomer feeding rate is 2 kg / h, the purified hexafluoropropylene monomer feeding rate is 0.2 kg / h, synchronously feed into the mixing container, after feeding is completed, start the stirring device, the rotating speed is 150 r / min, stir for 15 min, the pressure is 0.1 MPa, obtain monomer mixture B; S5: weigh the emulsifier ammonium perfluorobutyl sulfonate, the amount is 0.05% of the total weight of the purified tetrafluoroethylene and the purified hexafluoropropylene monomers; weigh the initiator cyclohexyl hydroperoxide, the amount is 0.01% of the total weight of the purified tetrafluoroethylene and the purified hexafluoropropylene monomers; prepare a composite chain transfer agent by mixing methane and ethanol at a molar ratio of 1:2, the total amount is 0.1% of the total weight of the purified tetrafluoroethylene and the purified hexafluoropropylene monomers; S6: add deionized water in the polymerization reactor, the amount of the deionized water is 150% of the total weight of the purified tetrafluoroethylene and the purified hexafluoropropylene monomers, add the emulsifier ammonium perfluorobutyl sulfonate in the deionized water, stir at 200 r / min until completely dissolved; Seal the reactor and vacuumize, place the monomer mixture A in the sealed reactor, the initial absolute pressure is 1.1 MPa, heat to 45℃, add the initiator to start polymerization, continuously add the monomer mixture B in 3 times, each time interval is 30 min, add the composite chain transfer agent, react for 2 h, obtain FEP emulsion; The mass ratio of the monomer mixture A and the monomer mixture B is 1:1; S7: add electrolyte solution to the FEP emulsion, the electrolyte solution is 2 wt% sodium sulfite solution, the amount of the electrolyte solution is 2% of the volume of the FEP emulsion, stir at 100 r / min to perform demulsification treatment, centrifuge to obtain polymer particles; Wash the polymer particles with deionized water for 2 times, each time for 15 min, dry the washed polymer particles at 130℃ for 5 h, then send the dried polymer particles into an extrusion granulation device to perform extrusion granulation, the extrusion temperature is 340℃, the pressure is 23 MPa, the extrusion speed is 1.0 m / min, obtain FEP resin.
[0020] Example 2: a preparation method of FEP resin, characterized in that, comprising the following steps: S1: tetrafluoroethylene monomer purification, tetrafluoroethylene monomer is introduced into a dehydration tower filled with 30 mesh 4A molecular sieves for dehydration treatment, the dehydration temperature is 30℃, the pressure is 0.2MPa, after dehydration, it is introduced into an adsorption tower filled with 30 mesh modified activated carbon to remove impurities, the adsorption temperature is 30℃, the pressure is 0.2MPa; According to the mass of activated carbon 12%, triethylenetetramine is weighed and dissolved in deionized water, and activated carbon is added to the solution at a solid-liquid ratio of 1:15, stirred at 60℃, 500r / min for 8h; centrifugation to obtain modified activated carbon.
[0021] S2: hexafluoropropylene monomer purification, hexafluoropropylene monomer is introduced into a dehydration tower filled with 30 mesh 3A molecular sieves for dehydration treatment, the dehydration temperature is 30℃, the pressure is 0.2MPa, after dehydration, it is introduced into an adsorption tower filled with 30 mesh activated alumina to remove impurities, the adsorption temperature is 30℃, the pressure is 0.2MPa; S3: preparation of monomer mixture A, a closed mixing container with stirring device is selected, the container is first dried, then dry nitrogen is introduced for replacement, the nitrogen flow rate is controlled at 10L / min, the replacement is carried out for 40min, the purified tetrafluoroethylene and the purified hexafluoropropylene are introduced into the mixing container at a molar ratio of 20:86, the introduction rate is controlled by mass flow meter, the introduction rate of purified tetrafluoroethylene monomer is 2kg / h, the introduction rate of purified hexafluoropropylene monomer is 5kg / h, the stirring device is started after the introduction is completed, the stirring speed is 300r / min, the stirring time is 30min, the pressure is 0.2MPa, and monomer mixture A is obtained; S4: preparation of monomer mixture B, another closed mixing container with stirring device is selected, the container is first dried, then dry nitrogen is introduced for replacement, the nitrogen flow rate is controlled at 10L / min, the replacement is carried out for 40min, the purified tetrafluoroethylene and the purified hexafluoropropylene are introduced into the mixing container at a molar ratio of 92:15, the introduction rate is controlled by mass flow meter, the introduction rate of purified tetrafluoroethylene monomer is 6kg / h, the introduction rate of purified hexafluoropropylene monomer is 1kg / h, the stirring device is started after the introduction is completed, the stirring speed is 300r / min, the stirring time is 30min, the pressure is 0.2MPa, and monomer mixture B is obtained; S5: the emulsifier ammonium perfluorobutyl sulfonate is weighed, the amount is 0.5% of the total monomer weight of purified tetrafluoroethylene and purified hexafluoropropylene; the initiator cyclohexyl hydroperoxide is weighed, the amount is 0.1% of the total monomer weight of purified tetrafluoroethylene and purified hexafluoropropylene; the composite chain transfer agent is prepared by mixing methane and ethanol at a molar ratio of 1:3, the total amount is 1% of the total monomer weight of purified tetrafluoroethylene and purified hexafluoropropylene; S6: adding deionized water in the polymerization reactor, the amount of deionized water is 180% of the total weight of purified tetrafluoroethylene and purified hexafluoropropylene monomers, adding emulsifier ammonium perfluorobutyl sulfonate in the deionized water, stirring at 400 r / min until completely dissolved; Sealing the reactor and vacuumizing, the monomer mixture A is placed in the sealed reactor with an initial absolute pressure of 1.5 MPa, the temperature is raised to 50℃, the initiator is added to start the polymerization, the monomer mixture B is continuously added for 5 times during the reaction, each time interval is 60 min, the composite chain transfer agent is added, the reaction is carried out for 6 h, and the FEP emulsion is obtained; The mass ratio of the monomer mixture A to the monomer mixture B is 1:1; S7: adding an electrolyte solution into the FEP emulsion, the electrolyte solution is a 5wt% sodium sulfite solution, the amount of the electrolyte solution is 5% of the volume of the FEP emulsion, stirring at 150 r / min to carry out demulsification treatment, and centrifuging to obtain polymer particles; The polymer particles are washed with deionized water for 3 times, each time for 30 min, the washed polymer particles are dried at 140℃ for 7 h, and then the dried polymer particles are sent into an extrusion granulation equipment to carry out extrusion granulation, the extrusion temperature is 360℃, the pressure is 27 MPa, and the extrusion speed is 1.5 m / min, and the FEP resin is obtained.
[0022] Embodiment 3: a preparation method of a FEP resin, characterized in that comprising the following steps: S1: purifying tetrafluoroethylene monomers, the tetrafluoroethylene monomers are dehydrated by being introduced into a dehydration tower filled with 25-mesh 4A molecular sieves, the dehydration temperature is 28℃, and the pressure is 0.2 MPa, and then the dehydrated tetrafluoroethylene monomers are introduced into an adsorption tower filled with 20-mesh modified activated carbon to remove impurities, the adsorption temperature is 26℃, and the pressure is 0.2 MPa; 8% of triethylenetetramine by mass of the activated carbon is weighed, dissolved in deionized water, the activated carbon is added to the solution at a solid-liquid ratio of 1:12, and stirring is carried out at 45℃ and 400 r / min for 6 h; and the modified activated carbon is obtained by centrifuging at 8000 r / min for 15 min; S2: purifying hexafluoropropylene monomers, the hexafluoropropylene monomers are dehydrated by being introduced into a dehydration tower filled with 28-mesh 3A molecular sieves, the dehydration temperature is 25℃, and the pressure is 0.1 MPa, and then the dehydrated hexafluoropropylene monomers are introduced into an adsorption tower filled with 18-mesh activated alumina to remove impurities, the adsorption temperature is 24℃, and the pressure is 0.2 MPa; S3: Preparation of monomer mixture A, a closed mixing container with stirring device was selected, the container was first dried, then dry nitrogen was introduced for replacement, the nitrogen flow rate was controlled at 7 L / min, and the replacement was performed for 36 min. Purified tetrafluoroethylene and purified hexafluoropropylene were introduced at a molar ratio of 16:82 through a mass flow meter to control the introduction rate. The introduction rate of purified tetrafluoroethylene monomer was 1.5 kg / h, and the introduction rate of purified hexafluoropropylene monomer was 3 kg / h. The mixture container was introduced synchronously. After the introduction was completed, the stirring device was started, the rotation speed was 240 r / min, the stirring was performed for 28 min, and the pressure was 0.1 MPa. Monomer mixture A was obtained; S4: Preparation of monomer mixture B, another closed mixing container with stirring device was selected, the container was first dried, then dry nitrogen was introduced for replacement, the nitrogen flow rate was controlled at 8 L / min, and the replacement was performed for 32 min. Purified tetrafluoroethylene and purified hexafluoropropylene were introduced at a molar ratio of 88:12 through a mass flow meter to control the introduction rate. The introduction rate of purified tetrafluoroethylene monomer was 5 kg / h, and the introduction rate of purified hexafluoropropylene monomer was 0.9 kg / h. The mixture container was introduced synchronously. After the introduction was completed, the stirring device was started, the rotation speed was 270 r / min, the stirring was performed for 24 min, and the pressure was 0.2 MPa. Monomer mixture B was obtained; S5: The emulsifier ammonium perfluorobutyl sulfonate was weighed, the amount was 0.2% of the total weight of purified tetrafluoroethylene and purified hexafluoropropylene monomers. The initiator cyclohexyl hydroperoxide was weighed, the amount was 0.07% of the total weight of purified tetrafluoroethylene and purified hexafluoropropylene monomers. The composite chain transfer agent was prepared by mixing methane and ethanol at a molar ratio of 1:3, and the total amount was 0.9% of the total weight of purified tetrafluoroethylene and purified hexafluoropropylene monomers; S6: Deionized water was added to the polymerization reactor, the amount of deionized water was 170% of the total weight of purified tetrafluoroethylene and purified hexafluoropropylene monomers. The emulsifier ammonium perfluorobutyl sulfonate was added to the deionized water, and the stirring was performed at 320 r / min until complete dissolution; The reactor was sealed and vacuumed. The monomer mixture A was placed in the sealed reactor with an initial absolute pressure of 1.3 MPa. The temperature was raised to 45-50°C. The initiator was added to start the polymerization. The monomer mixture B was continuously added in four times with an interval of 48 min. The composite chain transfer agent was added. The reaction was performed for 4 h to obtain the FEP emulsion; The mass ratio of the monomer mixture A and the monomer mixture B was 1:1; S7: The electrolyte solution was added to the FEP emulsion. The electrolyte solution was a 3 wt% sodium sulfite solution. The amount of electrolyte solution was 4% of the volume of FEP emulsion. The stirring was performed at 130 r / min for demulsification treatment. The polymer particles were obtained by centrifugation; The polymer particles are washed with deionized water for 3 times, each time for 25 min, and the washed polymer particles are dried at 140 DEG C for 6 h, and then the dried polymer particles are sent to an extrusion granulation device for extrusion granulation, with an extrusion temperature of 350 DEG C, a pressure of 25 MPa, and an extrusion speed of 1.3 m / min, to obtain the FEP resin.
[0023] Comparative Example 1: The difference between this comparative example and Example 3 is that the activated carbon is not modified.
[0024] Comparative Example 2: The difference between this comparative example and Example 3 is that the monomer mixture A and B are not prepared separately, but a monomer mixture C is prepared by mixing purified tetrafluoroethylene and purified hexafluoropropylene in a molar ratio of 104:94, and in the step S6, the monomer mixture C is directly placed in a sealed reactor and the complex chain transfer agent is added, and the reaction is carried out for 4 h to obtain the FEP emulsion.
[0025] Experimental Example 1: Tensile strength (MPa) test, measured according to GB / T 1040.1-2018; Experimental Example 2: Bending strength (MPa) test, measured according to GB / T 9341-2008; Experimental Example 3: Impact strength (kJ / m 2 ) test, measured according to GB / T 1043.1-2008; The test results are shown in the following table:
[0026] From the above table, it can be seen that in Comparative Example 1, the activated carbon is not modified, and in Comparative Example 2, the single mixture cannot control the dynamic stability of copolymerization composition, so the tensile strength, impact strength and bending strength are lower than those of the examples.
[0027] The above examples are only used to illustrate the technical solutions of the present application, but not limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions recorded in the foregoing examples can be modified, or some technical features can be replaced by equivalents; and these modifications or replacements will not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.
Claims
1. A method for producing a FEP resin, characterized by, The method comprises the following steps: S1: tetrafluoroethylene monomer purification, tetrafluoroethylene monomer is introduced into a dehydration tower filled with molecular sieves for dehydration treatment, and after dehydration, it is introduced into an adsorption tower filled with modified activated carbon to remove impurities; S2: hexafluoropropylene monomer purification, hexafluoropropylene monomer is introduced into a dehydration tower filled with molecular sieves for dehydration treatment, and after dehydration, it is introduced into an adsorption tower filled with activated alumina to remove impurities; S3: preparation of monomer mixture A, under a nitrogen atmosphere, purified tetrafluoroethylene and purified hexafluoropropylene are synchronously introduced into a mixing container at a molar ratio of 14-20:80-86, and after the introduction is completed, stirring is performed to obtain monomer mixture A; S4: preparation of monomer mixture B, under a nitrogen atmosphere, purified tetrafluoroethylene and purified hexafluoropropylene are synchronously introduced into a mixing container at a molar ratio of 85-92:8-15, and after the introduction is completed, stirring is started to obtain monomer mixture B; S5: the emulsifier ammonium perfluorobutyl sulfonate is weighed, and the amount is 0.05-0.5% of the total weight of purified tetrafluoroethylene and purified hexafluoropropylene monomers; the initiator cyclohexyl hydroperoxide is weighed, and the amount is 0.01-0.1% of the total weight of purified tetrafluoroethylene and purified hexafluoropropylene monomers; a composite chain transfer agent is prepared by mixing methane and ethanol at a molar ratio of 1:2-3, and the total amount is 0.1-1% of the total weight of purified tetrafluoroethylene and purified hexafluoropropylene monomers; S6: deionized water is added to the polymerization reactor, and the emulsifier ammonium perfluorobutyl sulfonate is added to the deionized water and stirred until completely dissolved; The reactor is sealed and vacuumed, the monomer mixture A is placed in the sealed reactor, the initiator is added to start polymerization, monomer mixture B is continuously added in multiple intervals during the reaction, and the composite chain transfer agent is added to obtain an FEP emulsion; S7: an electrolyte solution is added to the FEP emulsion, stirring is performed for demulsification treatment, centrifugation is performed to obtain polymer particles, the polymer particles are washed multiple times with deionized water, the washed polymer particles are dried, and the dried polymer particles are extruded and granulated to obtain FEP resin.
2. The method for producing a FEP resin according to claim 1, characterized by, S1 specifically refers to: tetrafluoroethylene monomer is introduced into a dehydration tower filled with 10-30 mesh 4A molecular sieves for dehydration treatment, the dehydration temperature is 20-30°C, and the pressure is 0.1-0.2 MPa; after dehydration, it is introduced into an adsorption tower filled with 10-30 mesh modified activated carbon to remove impurities, the adsorption temperature is 20-30°C, and the pressure is 0.1-0.2 MPa.
3. The method of producing a FEP resin according to claim 1, characterized by, The preparation method of the modified activated carbon is as follows: 5-12% of triethylenetetramine by mass of activated carbon is weighed, dissolved in deionized water, and the activated carbon is added to the solution at a solid-liquid ratio of 1:10-15, stirred at 30-60°C and 300-500 r / min for 5-8 h; and the modified activated carbon is obtained by centrifugation.
4. The method of producing a FEP resin according to claim 1, characterized by, S2 specifically refers to: hexafluoropropylene monomer is introduced into a dehydration tower filled with 10-30 mesh 3A molecular sieves for dehydration treatment, the dehydration temperature is 20-30°C, and the pressure is 0.1-0.2 MPa; after dehydration, it is introduced into an adsorption tower filled with 10-30 mesh activated alumina to remove impurities, the adsorption temperature is 20-30°C, and the pressure is 0.1-0.2 MPa.
5. The method of producing a FEP resin according to claim 1, characterized by, S3 is specifically: select a closed mixing container with stirring device, first dry the container, then replace with dry nitrogen, control the nitrogen flow rate of 5-10 L / min, replace for 20-40 min, control the feeding rate of purified tetrafluoroethylene and purified hexafluoropropylene by mass flow meter, the feeding rate of purified tetrafluoroethylene monomer is 0.5-2 kg / h, the feeding rate of purified hexafluoropropylene monomer is 2-5 kg / h, synchronously feed into the mixing container, after feeding is completed, start the stirring device, the rotating speed is 150-300 r / min, stir for 15-30 min, the pressure is 0.1-0.2 MPa, obtain monomer mixture A.
6. The method of producing a FEP resin according to claim 1, characterized by, S4 is specifically: select another closed mixing container with stirring device, first dry the container, then replace with dry nitrogen, control the nitrogen flow rate of 5-10 L / min, replace for 20-40 min, control the feeding rate of purified tetrafluoroethylene and purified hexafluoropropylene by mass flow meter, the feeding rate of purified tetrafluoroethylene monomer is 2-6 kg / h, the feeding rate of purified hexafluoropropylene monomer is 0.2-1 kg / h, synchronously feed into the mixing container, after feeding is completed, start the stirring device, the rotating speed is 150-300 r / min, stir for 15-30 min, the pressure is 0.1-0.2 MPa, obtain monomer mixture B.
7. The method of producing a FEP resin according to claim 1, characterized by, S6 is specifically: add deionized water in the polymerization reactor, the amount of the deionized water is 150-180% of the total monomer weight of purified tetrafluoroethylene and purified hexafluoropropylene, add emulsifier ammonium perfluorobutyl sulfonate in the deionized water, stir at 200-400 r / min until completely dissolved; Put the monomer mixture A in a sealed reactor, the initial absolute pressure is 1.1-1.5 MPa, heat to 45-50℃, add initiator to start polymerization, continuously supplement monomer mixture B for 3-5 times during the reaction, each interval is 30-60 min, add composite chain transfer agent, react for 2-6 h, obtain FEP emulsion; The mass ratio of the monomer mixture A and the monomer mixture B is 1:
1.
8. The method of producing a FEP resin according to claim 1, characterized by, S7 is specifically: add electrolyte solution in the FEP emulsion, the electrolyte solution is 2-5 wt% sodium sulfite solution, the amount of the electrolyte solution is 2-5% of the volume of the FEP emulsion, stir at 100-150 r / min to carry out demulsification treatment, centrifuge to obtain polymer particles, wash the polymer particles with deionized water for 2-3 times, each washing time is 15-30 min, dry the washed polymer particles at 130-140℃ for 5-7 h, then send the dried polymer particles into extrusion granulation equipment to carry out extrusion granulation, the extrusion temperature is 340-360℃, the pressure is 23-27 MPa, the extrusion speed is 1.0-1.5 m / min, obtain FEP resin.
9. A FEP resin prepared by the preparation method of the FEP resin according to any one of claims 1-8.