High-temperature-resistant ethylene-tetrafluoroethylene copolymer as well as preparation method and application thereof

Abstract

The invention discloses a high-temperature-resistant ethylene-tetrafluoroethylene copolymer as well as a preparation method and application thereof. The copolymer comprises the following raw materials: 10-30 parts of ethylene; 60 to 80 parts of tetrafluoroethylene; and 6 to 30 parts of 4-(trifluoromethyl) styrene. The preparation method comprises the following steps: adding a perfluorocarbon solvent and 4-(trifluoromethyl) styrene into a reaction kettle, stirring, and keeping the temperature at 30-50 DEG C; and adding a mixed gas of ethylene and tetrafluoroethylene and a perfluorobutyryl peroxide compound in a molar ratio of 1: 1 into the system to initiate a polymerization reaction under the reaction pressure of 1-4MPa for 15-30 minutes. The application comprises the following steps: adding the prepared high-temperature-resistant ethylene-tetrafluoroethylene copolymer into an extruder; extruding at the temperature of 260-300 DEG C to coat the outer surface of the electric wire or the cable; and carrying out annealing treatment on the wire or the cable coated with the high-temperature-resistant ethylene-tetrafluoroethylene copolymer at the annealing temperature of 120-180 DEG C for 12-24 hours. The preparation method of the high-temperature-resistant ethylene-tetrafluoroethylene copolymer is simple, low in cost and convenient for large-scale production and application.

Description

Technical Field

[0001] The invention relates to the field of fluorine-containing polymer materials, and in particular to a high-temperature resistant ethylene-tetrafluoroethylene copolymer and a preparation method and application thereof. Background Art

[0002] Ethylene tetrafluoroethylene copolymer (ETFE), a polymer material that combines excellent mechanical strength, low density and excellent radiation resistance, has attracted widespread attention and application as an insulation material for wires and cables in many high-tech fields such as automobile manufacturing, robotics and aerospace due to its unique physical and chemical properties. These properties of ETFE make it an ideal choice for maintaining electrical insulation and mechanical integrity in these extreme environments.

[0003] However, despite the many advantages of ETFE, its limitations in the processing process cannot be ignored. In particular, when the molar ratio of ethylene to tetrafluoroethylene is maintained at 1:1, the resulting copolymer has a high melting point, and the narrow range between its melting point and decomposition temperature becomes a significant challenge. During the extrusion process of the insulation layer of wires and cables, this characteristic often causes the material to be easily oxidized and decomposed at the processing temperature, which in turn causes undesirable phenomena such as polymer discoloration, surface blistering and cracking. What's more serious is that these changes will further aggravate the degradation of the mechanical properties of the copolymer in a high temperature environment, seriously affecting the reliability and service life of the product.

[0004] In order to overcome this problem, researchers have tried to introduce a third monomer into ETFE, which effectively lowers the melting point of ETFE and improves its thermal stability by breaking the alternating sequence structure of the original binary copolymer. This strategy aims to broaden the processing window and reduce the risk of thermal decomposition during processing. For example, the technology of introducing a specific modified third monomer into ETFE is recorded in US patents (US4338237, US3308107, US6602107, US3444148, US3847881). These modification attempts have improved the high-temperature tensile properties of ETFE materials to a certain extent.

[0005] Although the above modification methods have achieved certain results, the existing technology still faces many challenges. Most modified monomers are difficult to effectively prevent the disordered movement and entanglement of polymer chains at high temperatures due to the small size of the side chains, thus failing to fundamentally solve the problem of high-temperature cracking of materials. In addition, the introduction of modified monomers may also increase the complexity of the reaction process, making the control of reaction conditions more difficult, which undoubtedly increases production costs and uncertainty in quality control.

[0006] In summary, although ETFE has broad application prospects as an insulation material for wires and cables, how to maintain its excellent performance while solving the problems of thermal decomposition and mechanical property degradation caused by high temperature during processing is still a key technical problem that needs to be solved urgently. Summary of the invention

[0007] The purpose of the present invention is to provide a high temperature resistant ethylene-tetrafluoroethylene copolymer and a preparation method and application thereof.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is:

[0009] A high temperature resistant ethylene-tetrafluoroethylene copolymer, the raw materials of which include the following components in parts by weight:

[0010] 10-30 parts of ethylene;

[0011] 60-80 parts of tetrafluoroethylene;

[0012] 6 to 30 parts of 4-(trifluoromethyl)styrene.

[0013] According to a further technical solution, the molar proportion of ethylene in the copolymer is 40 to 60%.

[0014] According to a further technical solution, the molar proportion of tetrafluoroethylene in the copolymer is 40 to 60%.

[0015] In a further technical solution, the molar proportion of 4-(trifluoromethyl)styrene in the copolymer is 1 to 10%.

[0016] According to a further technical solution, the high temperature resistant ethylene-tetrafluoroethylene copolymer has a melt flow index of 5 to 30 g / 10 min and a melting point of 240 to 275°C.

[0017] Furthermore, the present invention also discloses a method for preparing a high temperature resistant ethylene-tetrafluoroethylene copolymer, comprising:

[0018] (1) adding a perfluorocarbon solvent and 4-(trifluoromethyl)styrene into a reaction kettle, stirring and maintaining the temperature at 30 to 50° C.;

[0019] (2) A mixed gas of ethylene and tetrafluoroethylene and a perfluorobutyryl peroxide compound (CF3CF2CF2CO-OO-OCCF2CF2CF3) in a molar ratio of 1:1 are added into the system to initiate a polymerization reaction, wherein the weight ratio of the perfluorocarbon solvent to the total mass of the three monomers of ethylene, tetrafluoroethylene and 4-(trifluoromethyl)styrene in the system is 5 to 20:1, the reaction pressure is 1 to 4 MPa, and the reaction time is 15 to 30 min, and finally a high temperature resistant ethylene-tetrafluoroethylene copolymer can be obtained.

[0020] In the above scheme, the preparation method uses a solution polymerization method;

[0021] In the above scheme, the copolymerization reaction is carried out in a fluorocarbon solvent, a fluorochloroalkane, or other organic solvent that can promote the dissolution and dispersion of the reaction monomers;

[0022] In the above scheme, the comonomers ethylene, tetrafluoroethylene and 4-(trifluoromethyl)styrene used in the synthesis process of the high temperature resistant ethylene-tetrafluoroethylene copolymer are all known materials and can be purchased.

[0023] Furthermore, the present invention also discloses an application of a high temperature resistant ethylene-tetrafluoroethylene copolymer, comprising:

[0024] (1) adding the prepared high temperature resistant ethylene-tetrafluoroethylene copolymer into an extruder;

[0025] (2) Extruded at a temperature of 260-300°C and coated on the outer surface of the wire or cable;

[0026] (3) annealing the wire or cable coated with the high temperature resistant ethylene-tetrafluoroethylene copolymer at a temperature of 120 to 180° C. for a time of 12 to 24 hours.

[0027] The terms “include,” “including,” “have,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0028] The terms used herein generally have the ordinary meanings of each term used in the art, in the context of the present invention, and in the specific context, unless otherwise noted. Certain terms used to describe the present invention will be discussed below or elsewhere in this specification to provide additional guidance to those skilled in the art regarding the description of the present invention.

[0029] The working principle and advantages of the present invention are as follows:

[0030] 1. 4-(trifluoromethyl)styrene is introduced as the third monomer in the raw materials of the present invention, wherein the trifluoromethyl group can reduce the reactivity of active bonds and free radical activity in the molecular chain through the inductive effect. At the same time, the benzene ring structure provides a certain rigidity and π-π conjugation effect, increases the glass transition temperature, and reduces the movement of the chain segment. Therefore, the ethylene-tetrafluoroethylene copolymer of the present invention has good thermal stability, and the initial decomposition temperature is as high as 350-400° C., which can meet the extrusion processing requirements under high temperature conditions, avoids the degradation of the ethylene-tetrafluoroethylene copolymer during the processing, and can be applied to cable insulation materials.

[0031] 2. The preparation method of the high temperature resistant ethylene-tetrafluoroethylene copolymer of the present invention is simple, low in cost, and convenient for large-scale production and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Attached Figure 1 Thermogravimetric curves of Examples 1 to 3 of the present invention and Comparative Example 1;

[0033] Attached Figure 2 This is the appearance diagram of sample 1 after heat aging treatment in Example 1 of the present invention;

[0034] Attached Figure 3 This is the appearance diagram of sample 2 after heat aging treatment in Example 2 of the present invention;

[0035] Attached Figure 4 This is the appearance diagram of sample 3 after heat aging treatment in Example 3 of the present invention;

[0036] Attached Figure 5 This is the appearance diagram of sample 4 after heat aging treatment in comparative example 1 of the present invention. DETAILED DESCRIPTION

[0037] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0038] The present invention will be clearly described below with drawings and detailed descriptions. After understanding the embodiments of the present invention, any person skilled in the art can make changes and modifications based on the techniques taught by the present invention without departing from the spirit and scope of the present invention.

[0039] Embodiment 1:

[0040] A 100 ml stainless steel autoclave equipped with stirring, temperature control, circulating heating, and circulating cooling water was filled with nitrogen until the oxygen content was less than 10 ppm, and then evacuated to 0.0001 MPa;

[0041] 0.058L of perfluorocarbon solvent and 1.72g (0.01mol) of 4-(trifluoromethyl)styrene were added into the reaction kettle, stirred and heated to 40°C; after the system temperature was constant, a mixed gas of ethylene and tetrafluoroethylene in a molar ratio of 1:1 was added into the system by a compressor until the pressure reached 2MPa;

[0042] A metering pump was used to add 0.1 ml of a perfluorobutyryl peroxide compound (CF3CF2CF2CO-OO-OCCF2CF2CF3) containing 0.005 g to initiate the polymerization reaction, and a mixed gas having an ethylene-tetrafluoroethylene molar ratio of 1:1 was continuously introduced to maintain the pressure at 2 MPa to allow the reaction to proceed continuously;

[0043] When the amount of mixed gas added reaches 5.76 g according to the pressure change calculation, the addition of mixed gas is stopped and the reaction is allowed to continue for 15 min before stopping the reaction;

[0044] The unreacted ethylene and tetrafluoroethylene monomers are recycled into a recovery tank, 4-(trifluoromethyl)styrene monomer is recovered, and the material is placed into a rake dryer through the reactor discharge valve, the reaction solvent is recovered, and the material is washed with deionized water for multiple times under heating to obtain a high temperature resistant ethylene-tetrafluoroethylene copolymer.

[0045] The heat stability test of the high temperature resistant ethylene-tetrafluoroethylene copolymer of Example 1 was carried out. The test results are shown in Tables 1 and Figure 1 shown.

[0046] Embodiment 2:

[0047] A 100 ml stainless steel autoclave equipped with stirring, temperature control, circulating heating, and circulating cooling water was filled with nitrogen until the oxygen content was less than 10 ppm, and then evacuated to 0.0001 MPa;

[0048] 0.058L perfluorocarbon solvent and 0.86g (0.01mol) of 4-(trifluoromethyl)styrene were added into the reaction kettle, stirred and heated to 40°C. After the system temperature was constant, a mixed gas of ethylene and tetrafluoroethylene in a molar ratio of 1:1 was added into the system by a compressor until the pressure reached 2MPa.

[0049] A metering pump was used to add 0.1 ml of a perfluorobutyryl peroxide compound (CF3CF2CF2CO-OO-OCCF2CF2CF3) containing 0.005 g to initiate the polymerization reaction, and a mixed gas having an ethylene-tetrafluoroethylene molar ratio of 1:1 was continuously introduced to maintain the pressure at 2 MPa to allow the reaction to proceed continuously;

[0050] When the amount of mixed gas added reaches 6.08 g according to the pressure change calculation, the addition of mixed gas is stopped and the reaction is allowed to continue for 15 min before stopping the reaction;

[0051] The unreacted ethylene and tetrafluoroethylene monomers are recycled into a recovery tank, 4-(trifluoromethyl)styrene monomer is recovered, and the material is placed into a rake dryer through the reactor discharge valve, the reaction solvent is recovered, and the material is washed with deionized water for multiple times under heating to obtain a high temperature resistant ethylene-tetrafluoroethylene copolymer.

[0052] The heat stability test of the high temperature resistant ethylene-tetrafluoroethylene copolymer of Example 2 was carried out. The test results are shown in Tables 1 and Figure 1 shown.

[0053] Embodiment 3:

[0054] A 100 ml stainless steel autoclave equipped with stirring, temperature control, circulating heating, and circulating cooling water was filled with nitrogen until the oxygen content was less than 10 ppm, and then evacuated to 0.0001 MPa;

[0055] 0.058L perfluorocarbon solvent and 0.43g (0.01mol) of 4-(trifluoromethyl)styrene were added into the reaction kettle, stirred and heated to 40°C. After the system temperature was constant, a mixed gas of ethylene and tetrafluoroethylene in a molar ratio of 1:1 was added into the system by a compressor until the pressure reached 2MPa.

[0056] A metering pump was used to add 0.1 ml of a perfluorobutyryl peroxide compound (CF3CF2CF2CO-OO-OCCF2CF2CF3) containing 0.005 g to initiate the polymerization reaction, and a mixed gas having an ethylene-tetrafluoroethylene molar ratio of 1:1 was continuously introduced to maintain the pressure at 2 MPa to allow the reaction to proceed continuously;

[0057] When the amount of mixed gas added reaches 6.24 g according to the pressure change calculation, stop adding the mixed gas and allow the reaction to continue for 15 min before stopping the reaction;

[0058] The unreacted ethylene and tetrafluoroethylene monomers are recycled into a recovery tank, 4-(trifluoromethyl)styrene monomer is recovered, and the material is placed into a rake dryer through the reactor discharge valve, the reaction solvent is recovered, and the material is washed with deionized water for multiple times under heating to obtain a high temperature resistant ethylene-tetrafluoroethylene copolymer.

[0059] The heat stability test of the high temperature resistant ethylene-tetrafluoroethylene copolymer of Example 3 was carried out. The test results are shown in Tables 1 and Figure 1 shown.

[0060] Comparative Example 1:

[0061] A 100 ml stainless steel autoclave equipped with stirring, temperature control, circulating heating, and circulating cooling water was filled with nitrogen until the oxygen content was less than 10 ppm, and then evacuated to 0.0001 MPa;

[0062] 0.058L of perfluorocarbon solvent was added into the reaction kettle, stirred and heated to 40°C. After the system temperature was constant, a mixed gas of ethylene and tetrafluoroethylene in a molar ratio of 1:1 was added into the system by a compressor until the pressure reached 2MPa.

[0063] A metering pump was used to add 0.1 ml of a perfluorobutyryl peroxide compound (CF3CF2CF2CO-OO-OCCF2CF2CF3) containing 0.005 g to initiate the polymerization reaction, and a mixed gas having an ethylene-tetrafluoroethylene molar ratio of 1:1 was continuously introduced to maintain the pressure at 2 MPa to allow the reaction to proceed continuously;

[0064] When the amount of mixed gas added reaches 6.40 g by calculating the pressure change, stop adding the mixed gas and allow the reaction to continue for 15 min before stopping the reaction;

[0065] The unreacted ethylene and tetrafluoroethylene monomers are recycled into a recovery tank, and the materials are placed into a rake dryer through the reactor discharge valve, the reaction solvent is recovered, and the materials are washed with deionized water for multiple times under heating to obtain ethylene-tetrafluoroethylene copolymer.

[0066] The thermal stability test of the ethylene-tetrafluoroethylene copolymer of Comparative Example 1 was carried out. The test results are shown in Tables 1 and Figure 1 shown.

[0067] Table 1

[0068]

[0069] Combined with Examples 1 to 3 and Comparative Example 1 and Table 1 and Figure 1 It can be seen that the high temperature resistant ethylene-tetrafluoroethylene copolymer has high thermal stability and can meet the requirements of extrusion processing under high temperature conditions. This is mainly due to the introduction of 4-(trifluoromethyl)styrene as the third monomer in Examples 1 to 3, which significantly improves the thermal stability of Examples 1 to 3 through the electronic effect generated and the rigid structure provided. However, since Comparative Example 1 does not introduce 4-(trifluoromethyl)styrene, its thermal stability is significantly lower than that of each Example.

[0070] Application of the high temperature resistant ethylene-tetrafluoroethylene copolymers of Examples 1 to 3 as wire insulation materials or cable insulation materials (for the convenience of observation, wires or cables are not used in the examples):

[0071] The high temperature resistant ethylene-tetrafluoroethylene copolymer of Example 1 was extruded through a screw extruder at an extrusion temperature of 275°C, and annealed at 150°C for 12 hours. Samples of corresponding sizes were cut according to test requirements, and then heat aged at 240°C in a high temperature aging box for 120 hours to obtain Sample 1.

[0072] The high temperature resistant ethylene-tetrafluoroethylene copolymer of Example 2 is extruded through a screw extruder at an extrusion temperature of 275°C, and annealed at 150°C for 12 hours. Samples of corresponding sizes are cut according to test requirements, and then heat aged at 240°C in a high temperature aging box for 120 hours to obtain Sample 2.

[0073] The high temperature resistant ethylene-tetrafluoroethylene copolymer of Example 3 was extruded through a screw extruder at an extrusion temperature of 275°C, and annealed at 150°C for 12 hours. Samples of corresponding sizes were cut according to test requirements, and then heat aged at 240°C in a high temperature aging box for 120 hours to obtain Sample 3.

[0074] The ethylene-tetrafluoroethylene copolymer of Comparative Example 1 was extruded through a screw extruder at an extrusion temperature of 275°C and annealed at 120°C for 12 hours. Samples of corresponding sizes were cut according to test requirements and then subjected to heat aging treatment at 240°C in a high-temperature aging box for 120 hours to obtain Sample 4.

[0075] like Figures 2 to 5 As shown, by observing the materials of sample 4 and samples 1 to 3 after annealing, it can be seen that sample 4 shows discoloration and blistering, and sample 1 only shows discoloration, while samples 2 to 3 corresponding to embodiments 2 to 3 of the present invention do not show discoloration or blistering, indicating that the high temperature resistant ethylene-tetrafluoroethylene copolymer of the present invention has good thermal stability as an insulating material for wires and cables.

[0076] Table 2

[0077] sample Sample 4 Sample 1 Sample 2 Sample 3 color Discoloration, yellowing Discoloration, yellowing No significant changes No significant changes Appearance Foaming No foaming No foaming No foaming

[0078] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A high temperature resistant ethylene-tetrafluoroethylene copolymer, characterized in that: The raw materials include the following components in parts by weight: 10-30 parts of ethylene; 60-80 parts of tetrafluoroethylene; 6 to 30 parts of 4-(trifluoromethyl)styrene.

2. A high temperature resistant ethylene-tetrafluoroethylene copolymer according to claim 1, characterized in that: The molar proportion of ethylene in the copolymer is 40-60%.

3. The high temperature resistant ethylene-tetrafluoroethylene copolymer according to claim 1, characterized in that: The molar proportion of tetrafluoroethylene in the copolymer is 40-60%.

4. The high temperature resistant ethylene-tetrafluoroethylene copolymer according to claim 1, characterized in that: The molar proportion of the 4-(trifluoromethyl)styrene in the copolymer is 1-10%.

5. The high temperature resistant ethylene-tetrafluoroethylene copolymer according to claim 1, characterized in that: The melt flow index of high temperature resistant ethylene-tetrafluoroethylene copolymer is 5~30g / 10min, and the melting point is 240~275℃.

6. A method for preparing a high temperature resistant ethylene-tetrafluoroethylene copolymer, characterized in that: For preparing the high temperature resistant ethylene-tetrafluoroethylene copolymer according to any one of claims 1 to 5, the preparation method comprises: (1) Add perfluorocarbon solvent and 4-(trifluoromethyl)styrene into the reaction kettle, stir and keep the temperature at 30-50°C; (2) A mixed gas of ethylene and tetrafluoroethylene and a perfluorobutyryl peroxide compound (CF3CF2CF2CO-OO-OCCF2CF2CF3) in a molar ratio of 1:1 is added into the system to initiate a polymerization reaction, wherein the weight ratio of the perfluorocarbon solvent to the total mass of the three monomers of ethylene, tetrafluoroethylene and 4-(trifluoromethyl)styrene in the system is 5-20:1, the reaction pressure is 1-4 MPa, and the reaction time is 15-30 min, and finally a high temperature resistant ethylene-tetrafluoroethylene copolymer can be obtained.

7. An application of a high temperature resistant ethylene-tetrafluoroethylene copolymer, characterized in that: include: (1) adding the high temperature resistant ethylene-tetrafluoroethylene copolymer prepared according to claim 6 into an extruder; (2) Extruded at a temperature of 260~300℃ and coated on the outer surface of the wire or cable; (3) Annealing the wire or cable coated with the high temperature resistant ethylene-tetrafluoroethylene copolymer at a temperature of 120 to 180° C. for a time of 12 to 24 hours.

Images