Corrosion-resistant folding-resistant PTFE composite material as well as preparation method and application thereof

Abstract

The invention discloses a corrosion-resistant folding-resistant PTFE composite material as well as a preparation method and application thereof. The preparation method of the corrosion-resistant folding-resistant PTFE composite material comprises the following steps: (1) by taking persulfate as an initiator, preparing a PTFE component I through a dispersion polymerization process; (2) by taking dibenzoyl peroxide as an initiator, preparing a PTFE component II through a dispersion polymerization process; and (3) blending and granulating the PTFE component I and the PTFE component II to obtain the corrosion-resistant folding-resistant PTFE composite material. According to the invention, the scheme that polytetrafluoroethylene is modified by adopting heterogeneous additives in the prior art is abandoned, polytetrafluoroethylene prepared by adopting different processes is adopted to modify polytetrafluoroethylene, and since all materials in the composite material are polytetrafluoroethylene, the condition of incompatibility does not exist; the anti-fatigue effect of the polytetrafluoroethylene material is far better than that of a polytetrafluoroethylene material obtained through heterogeneous compatibility, and the polytetrafluoroethylene material has excellent corrosion resistance and folding resistance.

Description

Technical Field

[0001] The invention belongs to the technical field, and specifically relates to a corrosion-resistant and folding-resistant PTFE composite material and a preparation method and application thereof. Background Art

[0002] Polytetrafluoroethylene diaphragms (also called PTFE seals, sealing rings, oil seals or PTFE diaphragm accessories) have excellent properties such as corrosion resistance, high temperature stability, wear resistance, and aging resistance. They can be used as dielectric materials in the fields of chemical, electronics, and medicine.

[0003] However, polytetrafluoroethylene (PTFE) is a chain polymer material whose basic molecular structure is composed of fluorocarbon. The fluorocarbon bond energy is as high as 485 kJ / mol, which results in very low surface energy and very high viscosity. It is difficult to effectively improve its physical properties through other substances. For polytetrafluoroethylene diaphragms, the currently commonly used additive modification technology belongs to heterogeneous modification technology. There are serious interface compatibility problems between additives and polytetrafluoroethylene. While the additives increase the tensile strength, it will inevitably lead to a decrease in its elongation at break, which makes the polytetrafluoroethylene diaphragm lack flexibility and elasticity and is not foldable. Summary of the invention

[0004] The purpose of the present invention is to provide a corrosion-resistant and folding-resistant PTFE composite material and a preparation method and application thereof, which have solved the problems existing in the prior art.

[0005] In order to achieve the above-mentioned object of the invention, the technical solution of the present invention is: A corrosion-resistant and folding-resistant PTFE composite material, the preparation method of which comprises the following steps: (1) Using persulfate as an initiator, PTFE component 1 is prepared by a dispersion polymerization process; (2) using dibenzoyl peroxide as an initiator, preparing PTFE component 2 through a dispersion polymerization process; (3) PTFE component one and PTFE component two are blended and granulated to obtain the corrosion-resistant and folding-resistant PTFE composite material.

[0006] The present invention abandons the scheme of modifying polytetrafluoroethylene with heterogeneous additives in the prior art, and instead uses polytetrafluoroethylene prepared by different processes to modify polytetrafluoroethylene. Since all materials in the composite material are polytetrafluoroethylene, there is no incompatibility. Its anti-fatigue effect is far greater than that of the polytetrafluoroethylene material obtained by heterogeneous compatibility, and it has excellent corrosion resistance and folding resistance.

[0007] Preferably, in step (1), the persulfate includes ammonium persulfate, potassium persulfate or sodium persulfate.

[0008] Preferably, the dispersion polymerization process in step (1) or step (2) comprises: (a) adding an initiator, 20-30% of an emulsifier, a stabilizer and high-purity water into a polymerization kettle and stirring them evenly, adding 20-40% of tetrafluoroethylene under an inert atmosphere, and heating to the polymerization temperature; (b) continuously adding the remaining 70-80% of the emulsifier and 60-80% of tetrafluoroethylene during the polymerization process; (c) After the reaction is completed, the polytetrafluoroethylene emulsion is taken out, and after coagulation, separation, washing and drying, the PTFE component one or PTFE component two is obtained.

[0009] Preferably, the emulsifier is ammonium perfluorooctanoate, and the stabilizer includes stearic acid or paraffin.

[0010] Preferably, in step (1), the polymerization temperature is 50-80°C and the polymerization pressure is 10-15 kgf / cm 2 , the polymerization time is 10-15 h.

[0011] Preferably, in step (2), the polymerization temperature is 70-100°C and the polymerization pressure is 20-30 kgf / cm 2 , the polymerization time is 10-20 h.

[0012] Preferably, in step (3), the mass ratio of PTFE component one to PTFE component two is 10:(4-6).

[0013] Preferably, in step (3), the blending and granulation is carried out at 330-350°C.

[0014] The present invention also provides the use of the above-mentioned corrosion-resistant and folding-resistant PTFE composite material in the preparation of a diaphragm. The PTFE composite material prepared by the present invention has a small particle size and can be relatively evenly dispersed in a mold, which not only reduces the internal stress concentration effect, but also can effectively ensure the uniformity of crystallinity everywhere; this makes the prepared diaphragm not easy to be damaged and greatly extends its service life.

[0015] Compared with the prior art, the technical effects of the present invention are embodied in: (1) The present invention abandons the scheme of modifying polytetrafluoroethylene with heterogeneous additives in the prior art, and instead uses polytetrafluoroethylene prepared by different processes to modify polytetrafluoroethylene. Since all materials in the composite material are polytetrafluoroethylene, there is no incompatibility. Its anti-fatigue effect is much greater than that of the polytetrafluoroethylene material obtained by heterogeneous compatibility, and it has excellent corrosion resistance and folding resistance.

[0016] (2) The PTFE composite material prepared by the present invention has a small particle size and can be relatively evenly dispersed in the mold, which not only reduces the internal stress concentration effect, but also effectively ensures the uniformity of crystallinity everywhere; this makes the prepared diaphragm sheet less prone to damage and greatly extends its service life. DETAILED DESCRIPTION

[0017] The following examples are given to further illustrate the technical solution of the present invention.

[0018] Example 1 The present embodiment provides a corrosion-resistant and folding-resistant PTFE composite material, and the preparation method thereof comprises the following steps: (1) Using persulfate as an initiator, PTFE component 1 is prepared by a dispersion polymerization process; Specifically, it includes: (a) Add initiator, 20% emulsifier, stabilizer and high-purity water into a polymerization kettle and stir evenly, introduce nitrogen into the polymerization kettle to expel oxygen in the polymerization kettle; then add 20% tetrafluoroethylene under nitrogen atmosphere, raise the temperature to 50°C and set the polymerization pressure to 15 kgf / cm 2 To aggregate; The initiator used in this embodiment is potassium persulfate, the emulsifier is ammonium perfluorooctanoate, the stabilizer is paraffin, and the mass ratio of the initiator, emulsifier, stabilizer and tetrafluoroethylene is 0.02:0.6:10:100; In this embodiment, the emulsifier and tetrafluoroethylene are added in two stages, and only 20% of the total emulsifier amount and 20% of the total tetrafluoroethylene amount are added before the reaction starts; (b) continuously adding the remaining 80% of the emulsifier and 80% of tetrafluoroethylene during the polymerization process; The duration of continuous addition of emulsifier and tetrafluoroethylene was equivalent to the duration of the polymerization reaction, which was 15 h; (c) after the reaction is completed, the polytetrafluoroethylene emulsion is taken out, and after coagulation, separation, washing and drying, the PTFE component 1 is obtained; Specifically, nitrogen is continuously introduced into the polymerization kettle for 10 minutes after the reaction is completed, and the polytetrafluoroethylene emulsion is taken out after the polymerization kettle cools to room temperature, and then the PTFE component 1 is obtained through conventional coagulation, separation, washing and drying processes; (2) using dibenzoyl peroxide as an initiator, preparing PTFE component 2 through a dispersion polymerization process; The dispersion polymerization process of PTFE component 2 is basically the same as step (1), except that: the initiator used is dibenzoyl peroxide, the stabilizer is fatty acid; the mass ratio of initiator, emulsifier, stabilizer and tetrafluoroethylene is 0.03:0.8:15:100; the polymerization temperature is 70°C, and the polymerization pressure is 30 kgf / cm2 , the polymerization time is 20 h; (3) PTFE component one and PTFE component two are blended and granulated to obtain the corrosion-resistant and folding-resistant PTFE composite material of this embodiment; Specifically, the mass ratio of PTFE component one to PTFE component two is 10:4, and the blending and granulation is performed at 330°C.

[0019] Example 2 The present embodiment provides a corrosion-resistant and folding-resistant PTFE composite material, and the preparation method thereof comprises the following steps: (1) Using persulfate as an initiator, PTFE component 1 is prepared by a dispersion polymerization process; Specifically, it includes: (a) Add initiator, 25% emulsifier, stabilizer and high-purity water into a polymerization kettle and stir evenly, introduce nitrogen into the polymerization kettle to expel oxygen in the polymerization kettle; then add 30% tetrafluoroethylene under nitrogen atmosphere, raise the temperature to 60°C and set the polymerization pressure to 15 kgf / cm 2 To aggregate; The initiator used in this embodiment is potassium persulfate, the emulsifier is ammonium perfluorooctanoate, the stabilizer is paraffin, and the mass ratio of the initiator, emulsifier, stabilizer and tetrafluoroethylene is 0.02:0.6:10:100; In this embodiment, the emulsifier and tetrafluoroethylene are added in two stages, and only 25% of the total emulsifier amount and 30% of the total tetrafluoroethylene amount are added before the reaction starts; (b) continuously adding the remaining 75% of the emulsifier and 70% of tetrafluoroethylene during the polymerization process; The duration of continuous addition of emulsifier and tetrafluoroethylene was equivalent to the duration of the polymerization reaction, which was 15 h; (c) after the reaction is completed, the polytetrafluoroethylene emulsion is taken out, and after coagulation, separation, washing and drying, the PTFE component 1 is obtained; Specifically, nitrogen is continuously introduced into the polymerization kettle for 10 minutes after the reaction is completed, and the polytetrafluoroethylene emulsion is taken out after the polymerization kettle cools to room temperature, and then the PTFE component 1 is obtained through conventional coagulation, separation, washing and drying processes; (2) using dibenzoyl peroxide as an initiator, preparing PTFE component 2 through a dispersion polymerization process; The dispersion polymerization process of PTFE component 2 is basically the same as step (1), except that: the initiator used is dibenzoyl peroxide, the stabilizer is fatty acid; the mass ratio of initiator, emulsifier, stabilizer and tetrafluoroethylene is 0.03:0.8:15:100; the polymerization temperature is 85°C, and the polymerization pressure is 25 kgf / cm 2 , the polymerization time is 18 h; (3) PTFE component one and PTFE component two are blended and granulated to obtain the corrosion-resistant and folding-resistant PTFE composite material of this embodiment; Specifically, the mass ratio of PTFE component one to PTFE component two is 10:5, and the blending and granulation is performed at 340°C.

[0020] Example 3 The present embodiment provides a corrosion-resistant and folding-resistant PTFE composite material, and the preparation method thereof comprises the following steps: (1) Using persulfate as an initiator, PTFE component 1 is prepared by a dispersion polymerization process; Specifically, it includes: (a) Add initiator, 30% emulsifier, stabilizer and high-purity water into a polymerization kettle and stir evenly, introduce nitrogen into the polymerization kettle to expel oxygen in the polymerization kettle; then add 40% tetrafluoroethylene under nitrogen atmosphere, raise the temperature to 80°C and set the polymerization pressure to 10 kgf / cm 2 To aggregate; The initiator used in this embodiment is potassium persulfate, the emulsifier is ammonium perfluorooctanoate, the stabilizer is paraffin, and the mass ratio of the initiator, emulsifier, stabilizer and tetrafluoroethylene is 0.02:0.6:10:100; In this embodiment, the emulsifier and tetrafluoroethylene are added in two stages, and only 30% of the total emulsifier amount and 40% of the total tetrafluoroethylene amount are added before the reaction starts; (b) continuously adding the remaining 70% of the emulsifier and 60% of tetrafluoroethylene during the polymerization process; The duration of continuous addition of emulsifier and tetrafluoroethylene was equivalent to the duration of the polymerization reaction, which was 10 h; (c) after the reaction is completed, the polytetrafluoroethylene emulsion is taken out, and after coagulation, separation, washing and drying, the PTFE component 1 is obtained; Specifically, nitrogen is continuously introduced into the polymerization kettle for 10 minutes after the reaction is completed, and the polytetrafluoroethylene emulsion is taken out after the polymerization kettle cools to room temperature, and then the PTFE component 1 is obtained through conventional coagulation, separation, washing and drying processes; (2) using dibenzoyl peroxide as an initiator, preparing PTFE component 2 through a dispersion polymerization process; The dispersion polymerization process of PTFE component 2 is basically the same as step (1), except that: the initiator used is dibenzoyl peroxide, the stabilizer is fatty acid; the mass ratio of initiator, emulsifier, stabilizer and tetrafluoroethylene is 0.03:0.8:15:100; the polymerization temperature is 100°C, and the polymerization pressure is 20 kgf / cm 2 , the polymerization time is 15 h; (3) PTFE component one and PTFE component two are blended and granulated to obtain the corrosion-resistant and folding-resistant PTFE composite material of this embodiment; Specifically, the mass ratio of PTFE component one to PTFE component two is 10:6, and the blending and granulation is performed at 350°C.

[0021] Example 4 This embodiment is a corrosion-resistant and folding-resistant PTFE composite material, and its preparation method is basically the same as that of Example 2, except that the dispersion polymerization process (polymerization temperature, polymerization pressure and polymerization time) of PTFE component two is the same as the dispersion polymerization process of PTFE component one.

[0022] Example 5 This embodiment is a corrosion-resistant and folding-resistant PTFE composite material, and its preparation method is basically the same as that of Example 2, except that the mass ratio of PTFE component one to PTFE component two is 1:1.

[0023] Example 6 This embodiment is a corrosion-resistant and folding-resistant PTFE composite material, and its preparation method is basically the same as that of Example 2, except that the mass ratio of PTFE component one to PTFE component two is 1:2.

[0024] The properties of the PTFE composite materials prepared in Examples 1-6 were tested, and the results are shown in Table 1.

[0025] Table 1 As can be seen from Table 1, the PTFE composite material prepared by the present invention has excellent physical properties, and the PTFE composite material prepared by Examples 1-3 has better performance, as shown by: the number of folding resistance exceeds 200,000 times, the tensile strength reaches more than 75 MPa, and the elongation at break reaches more than 550%; the material is placed in 240°C, 50% concentrated hydrochloric acid or sodium hydroxide for 24 hours, and there is basically no change. It shows that the PTFE composite material of the present invention is corrosion-resistant, folding-resistant, and has excellent mechanical properties.

Claims

1. A method for preparing a corrosion-resistant and folding-resistant PTFE composite material, characterized in that: The following steps are involved: (1) Using persulfate as an initiator, PTFE component 1 is prepared by a dispersion polymerization process; (2) using dibenzoyl peroxide as an initiator, preparing PTFE component 2 through a dispersion polymerization process; (3) PTFE component one and PTFE component two are blended and granulated to obtain the corrosion-resistant and folding-resistant PTFE composite material.

2. The preparation method according to claim 1, characterized in that In step (1), the persulfate includes ammonium persulfate, potassium persulfate or sodium persulfate.

3. The preparation method according to claim 1, characterized in that: The dispersion polymerization process described in step (1) or step (2) comprises: (a) adding an initiator, 20-30% of an emulsifier, a stabilizer and high-purity water into a polymerization kettle and stirring them evenly, adding 20-40% of tetrafluoroethylene under an inert atmosphere, and heating to the polymerization temperature; (b) continuously adding the remaining 70-80% of the emulsifier and 60-80% of tetrafluoroethylene during the polymerization process; (c) After the reaction is completed, the polytetrafluoroethylene emulsion is taken out, and after coagulation, separation, washing and drying, the PTFE component one or PTFE component two is obtained.

4. The preparation method according to claim 3, characterized in that: The emulsifier is ammonium perfluorooctanoate, and the stabilizer includes stearic acid or paraffin.

5. The preparation method according to claim 3, characterized in that: In step (1), the polymerization temperature is 50-80°C and the polymerization pressure is 10-15 kgf / cm 2 , the polymerization time is 10-15 h.

6. The preparation method according to claim 3, characterized in that: In step (2), the polymerization temperature is 70-100°C and the polymerization pressure is 20-30 kgf / cm 2 , the polymerization time is 10-20 h.

7. The preparation method according to claim 1, characterized in that: In step (3), the mass ratio of PTFE component one to PTFE component two is 10:(4-6).

8. The preparation method according to claim 1, characterized in that: In step (3), the blending and granulation is carried out at 330-350°C.

9. A corrosion-resistant and folding-resistant PTFE composite material, characterized in that: The method is prepared according to any one of claims 1 to 8.

10. Use of the corrosion-resistant and folding-resistant PTFE composite material according to claim 9 in preparing a diaphragm sheet.

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