Corrosion-resistant fluororubber for screw pump and preparation method of corrosion-resistant fluororubber

Abstract

The invention provides corrosion-resistant fluororubber for a screw pump and a preparation method of the corrosion-resistant fluororubber. The corrosion-resistant fluororubber is prepared from the following raw materials in parts by weight: 100-180 parts of raw fluororubber, 15-25 parts of fumed silica, 5-10 parts of polytetrafluoroethylene micro powder, 5-15 parts of an acid acceptor, 1.5-3 parts of a vulcanizing agent, 0.8-1.5 parts of an accelerant and 2-4 parts of a processing aid. The preparation method of the corrosion-resistant fluororubber for the screw pump comprises the following steps: S1, pretreating raw materials; s2, a mixing process; s3, performing a pre-forming process; s4, a vulcanization process; and S5, forming process. The screw pump stator provided by the invention has excellent corrosion resistance, high temperature resistance and stable chemical properties. The stator is excellent in performance under harsh working conditions in the industries of chemical engineering, petroleum, pharmacy and the like, and the overall performance and stability of the screw pump are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of rubber, and in particular to a corrosion-resistant fluororubber for a screw pump and a preparation method thereof. Background Art

[0002] In industrial production, screw pumps, as key fluid conveying equipment, are widely used in chemical, petroleum, pharmaceutical, food and other fields. With the advancement of industrial technology, the complexity of conveying media and the severity of working conditions are constantly increasing. Traditional rubber materials (such as nitrile rubber and chloroprene rubber) are gradually unable to meet the requirements in terms of corrosion resistance, high temperature resistance and chemical stability. For example, the chemical industry often needs to transport strong acids, strong bases or organic solvents, the petroleum industry faces high temperature and high pressure drilling fluid transportation, the pharmaceutical industry has extremely high requirements for medium purity, and the food industry needs to cope with high temperature sterilization and other processes. These scenarios place higher demands on the sealing and durability of screw pumps.

[0003] The development of fluororubber (FKM) began in the 1940s, with DuPont producing poly-2-fluoro-1,3-butadiene and its copolymers in 1948. Although early products had limited performance and high costs, their potential in extreme environments gradually became apparent. In 1958, DuPont launched the Viton series of fluororubber, marking the beginning of its commercial application. Its chemical resistance covers most media, including strong acids, strong bases, and organic solvents, making it the preferred sealing material in industries such as aerospace and automotive manufacturing.

[0004] Traditional screw pump stator materials (such as nitrile rubber, hydrogenated nitrile rubber) are prone to swelling, aging and failure in high temperatures (>150°C), strong acids / alkalis or organic solvents.

[0005] Ordinary fluororubber (FKM) has a limited range of chemical resistance, and is not resistant enough to concentrated sulfuric acid, strong alkali, esters, etc., and has large permanent compression deformation at high temperatures.

[0006] A new type of corrosion-resistant fluororubber for screw pumps is now needed to solve the above-mentioned problems. Summary of the Invention

[0007] The present invention provides a corrosion-resistant fluororubber for a screw pump and a preparation method thereof, and solves the problem of poor corrosion resistance and high temperature resistance of the existing screw pump by technically transforming the material of the existing screw pump stator.

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

[0009] A corrosion-resistant fluororubber for a screw pump comprises the following raw materials in parts by weight: 100-180 parts of fluororubber raw rubber, 15-25 parts of fumed silica, 5-10 parts of polytetrafluoroethylene micropowder, 5-15 parts of an acid absorber, 1.5-3 parts of a vulcanizing agent, 0.8-1.5 parts of an accelerator, and 2-4 parts of a processing aid.

[0010] Preferably, the acid scavenger is magnesium oxide and calcium hydroxide, the weight portion of the magnesium oxide is 3-10 parts, and the weight portion of the calcium hydroxide is 2-5 parts.

[0011] Preferably, the vulcanizing agent is bisphenol AF.

[0012] Preferably, the accelerator is benzyltriphenylphosphonium chloride.

[0013] Preferably, the processing aids are hydroxy silicone oil and low molecular weight polyethylene, the weight portion of the hydroxy silicone oil is 1-2 parts, and the weight portion of the low molecular weight polyethylene is 1-2 parts.

[0014] Preferably, it further comprises 3-8 parts by weight of carbon fiber chopped strands, wherein the carbon fiber chopped strands have a diameter of 5-10 μm and a length of 0.1-0.5 mm.

[0015] A method for preparing corrosion-resistant fluororubber for a screw pump comprises the following steps:

[0016] S1. Raw material pretreatment: pass the fluororubber rubber through the open mill for 3 times with the roller temperature at 40-50°C, and add hydroxy silicone oil to mix;

[0017] S2. Mixing process:

[0018] S201, plasticizing the fluororubber raw rubber in an internal mixer for 10-15 minutes;

[0019] S202, adding fumed silica, magnesium oxide, polytetrafluoroethylene powder, carbon fiber chopped strands, bisphenol AF and benzyl triphenyl phosphonium chloride to an internal mixer in sequence to ensure uniform mixing of the rubber materials;

[0020] S3, preforming process, forming the mixed rubber into a tubular blank through an extruder;

[0021] S4, vulcanization process:

[0022] S401, the first vulcanization, using a flat vulcanizing machine for vulcanization and molding, the vulcanization temperature is controlled at 170 ℃ -180 ℃, the vulcanization time is 20-40 minutes;

[0023] S402, the second vulcanization, during which appropriate pressure is applied to ensure that the fluororubber is fully cross-linked, and the temperature is gradually raised to 230°C and kept at this temperature for 24 hours to improve the density and performance stability of the stator;

[0024] S5. Molding process: compression molding or injection molding is used to process the vulcanized fluororubber into the screw pump stator. The mold temperature and molding pressure are controlled during the molding process to ensure the dimensional accuracy and performance consistency of the screw pump stator.

[0025] Preferably, in step S201, the speed of the internal mixer is 30-40 r / min, and the plasticizing temperature of the internal mixer is controlled at 60° C.-70° C.;

[0026] In step S202, the mixing temperature is controlled at 70°C-80°C and the mixing time is 20-30 minutes to ensure that the rubber materials are evenly mixed.

[0027] The beneficial effects of the present invention are:

[0028] 1) The fluororubber compound of the present invention has high corrosion resistance and excellent tolerance to strong oxidizing acids (such as sulfuric acid and nitric acid), organic solvents (such as benzene and chlorinated hydrocarbons) and high-temperature media, and is suitable for transporting corrosive media in the chemical and petroleum industries.

[0029] 2) The present application is added with fumed silica, which has high temperature resistance and can work for a long time in an environment of 200℃ to 250℃, and can withstand a short-term temperature of 300℃, meeting the requirements of high-temperature sterilization, drilling fluid circulation and other working conditions.

[0030] 3) Stronger chemical stability, anti-aging, anti-ozone, and radiation resistance, which extends equipment maintenance cycle, reduces downtime costs, and the fluororubber stator has a longer life.

[0031] 4) Stronger mechanical properties, high strength, high elasticity, good wear resistance, suitable for high pressure and high viscosity medium transportation, reducing friction loss between stator and rotor.

[0032] By optimizing the fluororubber formulation and preparation process, this paper successfully developed a screw pump stator material with excellent corrosion resistance, high temperature resistance, and chemical stability. This material performs exceptionally well under the demanding operating conditions of industries such as the chemical, petroleum, and pharmaceutical industries, significantly improving the overall performance and stability of screw pumps and possessing broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a production process diagram of the present invention; DETAILED DESCRIPTION

[0034] The specific contents of the present invention are described in detail below with reference to the accompanying drawings and embodiments.

[0035] The present application provides a corrosion-resistant fluororubber for a screw pump, comprising the following raw materials in parts by weight: 100-180 parts of fluororubber raw rubber, 15-25 parts of fumed silica, 5-10 parts of polytetrafluoroethylene micropowder, 5-15 parts of an acid absorber, 1.5-3 parts of a vulcanizing agent, 0.8-1.5 parts of an accelerator, and 2-4 parts of a processing aid.

[0036] Furthermore, the acid absorber is magnesium oxide and calcium hydroxide, with the magnesium oxide accounting for 3-10 parts by weight and the calcium hydroxide accounting for 2-5 parts by weight. Magnesium oxide and calcium hydroxide can neutralize hydrogen fluoride generated during processing, protect equipment, improve rubber fluidity, and reduce compression set.

[0037] Furthermore, the vulcanizing agent is bisphenol AF. Bisphenol AF can promote the cross-linking of fluororubber and improve its high temperature resistance and corrosion resistance.

[0038] Furthermore, the accelerator is benzyltriphenylphosphonium chloride (BPP).

[0039] Furthermore, the processing aids are hydroxy silicone oil and low molecular weight polyethylene, wherein the weight portion of the hydroxy silicone oil is 1-2 parts, and the weight portion of the low molecular weight polyethylene is 1-2 parts. The processing aids hydroxy silicone oil and low molecular weight polyethylene can prevent scorch and improve the fluidity of the rubber compound.

[0040] Furthermore, the invention also contains 3-8 parts by weight of carbon fiber chopped strands, wherein the carbon fiber chopped strands have a diameter of 5-10 μm and a length of 0.1-0.5 mm. The carbon fiber chopped strands can enhance mechanical strength and wear resistance.

[0041] This application uses a mixture of polytetrafluoroethylene micropowder and carbon fiber chopped strands. The polytetrafluoroethylene micropowder can reduce the permeability of the medium, and the carbon fiber chopped strands can improve the mechanical strength, with a tensile strength of ≥18MPa.

[0042] Magnesium oxide and fumed silica form an acid-resistant "buffer layer" that is more resistant to corrosion and high temperatures.

[0043] In a specific embodiment 1, 100 parts of fluororubber raw rubber, 20 parts of fumed silica, 8 parts of polytetrafluoroethylene powder, 5 parts by weight of magnesium oxide, 2 parts by weight of calcium hydroxide, 2.2 parts of bisphenol AF, 1 part of benzyltriphenylphosphonium chloride, 2 parts by weight of hydroxy silicone oil, 2 parts by weight of low molecular weight polyethylene, and 5 parts by weight of carbon fiber chopped strands.

[0044] A method for preparing corrosion-resistant fluororubber for a screw pump comprises the following steps:

[0045] S1. Raw material pretreatment: pass the fluororubber rubber through the open mill for 3 times with the roller temperature at 40-50°C, and add hydroxy silicone oil to mix;

[0046] S2. Mixing process:

[0047] S201, plasticizing the fluororubber raw rubber in an internal mixer for 10-15 minutes;

[0048] S202, adding fumed silica, magnesium oxide, polytetrafluoroethylene powder, carbon fiber chopped strands, bisphenol AF and benzyl triphenyl phosphonium chloride to an internal mixer in sequence to ensure uniform mixing of the rubber materials;

[0049] S3, preforming process, forming the mixed rubber into a tubular blank through an extruder;

[0050] S4, vulcanization process:

[0051] S401, the first vulcanization, using a flat vulcanizing machine for vulcanization and molding, the vulcanization temperature is controlled at 170 ℃ -180 ℃, the vulcanization time is 20-40 minutes;

[0052] S402, the second vulcanization, during which appropriate pressure is applied to ensure that the fluororubber is fully cross-linked, and the temperature is gradually raised to 230°C and kept at this temperature for 24 hours to improve the density and performance stability of the stator;

[0053] S5. Molding process: compression molding or injection molding is used to process the vulcanized fluororubber into the screw pump stator. The mold temperature and molding pressure are controlled during the molding process to ensure the dimensional accuracy and performance consistency of the screw pump stator.

[0054] Furthermore, in step S201, the speed of the internal mixer is 30-40 r / min, and the plasticizing temperature of the internal mixer is controlled at 60° C.-70° C.;

[0055] In step S202, the mixing temperature is controlled at 70°C-80°C and the mixing time is 20-30 minutes to ensure that the rubber materials are evenly mixed.

[0056] The present application adopts low-temperature mixing and step vulcanization methods, which can avoid scorching, achieve permanent compression deformation after two-stage vulcanization, and a volume expansion rate of ≤5% in concentrated sulfuric acid (40%) for 72 hours.

[0057] Technical verification of this application product:

[0058] Corrosion resistance: The fluororubber stator was immersed in highly corrosive media such as concentrated sulfuric acid and concentrated hydrochloric acid, and its surface changes were observed. The experimental results showed that there were no obvious signs of corrosion on the stator surface, and the mass loss rate was less than 1%.

[0059] High-temperature resistance: The fluororubber stator was placed in a high-temperature aging chamber and subjected to aging tests at 200°C, 250°C, and 300°C. The results showed that after aging for 1000 hours at 200°C, the stator retained more than 80% of its tensile strength; after aging for 300 hours at 250°C, the tensile strength retention rate was more than 70%; and after aging for 48 hours at 300°C, it still maintained a certain degree of elasticity.

[0060] Chemically stable: Fluororubber stators were exposed to UV rays, ozone, and other environments for long periods of time to observe changes in their performance. The experimental results showed no noticeable cracks on the stator surface, and changes in tensile strength and elongation were less than 5%.

[0061] The present invention has the following advantages:

[0062] 1) The fluororubber compound of the present invention has high corrosion resistance and excellent tolerance to strong oxidizing acids (such as sulfuric acid and nitric acid), organic solvents (such as benzene and chlorinated hydrocarbons) and high-temperature media, and is suitable for transporting corrosive media in the chemical and petroleum industries.

[0063] 2) The present application is added with fumed silica, which has high temperature resistance and can work for a long time in an environment of 200℃ to 250℃, and can withstand a short-term temperature of 300℃, meeting the requirements of high-temperature sterilization, drilling fluid circulation and other working conditions.

[0064] 3) Stronger chemical stability, anti-aging, anti-ozone, and radiation resistance, which extends equipment maintenance cycle, reduces downtime costs, and the fluororubber stator has a longer life.

[0065] 4) Stronger mechanical properties, high strength, high elasticity, good wear resistance, suitable for high pressure and high viscosity medium transportation, reducing friction loss between stator and rotor.

[0066] By optimizing the fluororubber formulation and production process, this paper successfully developed a screw pump stator material with excellent corrosion resistance, high temperature resistance, and chemical stability. This material performs exceptionally well under the demanding operating conditions of industries such as the chemical, petroleum, and pharmaceutical industries, significantly improving the overall performance and stability of screw pumps and possessing broad application prospects.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

[0068] The standard parts used in the present invention can all be purchased from the market, and special-shaped parts can be customized according to the description in the specification and the drawings. The specific connection methods of each part adopt conventional means such as mature bolts, rivets, welding, etc. in the existing technology. The machinery, parts and equipment all adopt conventional models in the existing technology, and the circuit connection adopts the conventional connection method in the existing technology, which will not be described in detail here.

[0069] In the description of the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they may refer to fixed or detachable connections, or integration; mechanical or electrical connections; direct or through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

Claims

1. A corrosion-resistant fluororubber for a screw pump, characterized in that: The invention comprises the following raw materials in parts by weight: 100-180 parts of fluororubber raw rubber, 15-25 parts of fumed silica, 5-10 parts of polytetrafluoroethylene micropowder, 5-15 parts of acid absorber, 1.5-3 parts of vulcanizing agent, 0.8-1.5 parts of accelerator and 2-4 parts of processing aid.

2. The corrosion-resistant fluororubber of a screw pump according to claim 1, characterized in that: The acid absorber is magnesium oxide and calcium hydroxide, the weight portion of the magnesium oxide is 3-10 parts, and the weight portion of the calcium hydroxide is 2-5 parts.

3. The corrosion-resistant fluororubber of a screw pump according to claim 1, characterized in that: The vulcanizing agent is bisphenol AF.

4. The corrosion-resistant fluororubber of a screw pump according to claim 1, characterized in that: The accelerator is benzyltriphenylphosphonium chloride.

5. The corrosion-resistant fluororubber of a screw pump according to claim 1, characterized in that: The processing aids are hydroxy silicone oil and low molecular polyethylene, the weight portion of the hydroxy silicone oil is 1-2 parts, and the weight portion of the low molecular polyethylene is 1-2 parts.

6. The corrosion-resistant fluororubber of a screw pump according to claim 1, characterized in that: The invention also contains 3-8 parts by weight of carbon fiber chopped strands, wherein the carbon fiber chopped strands have a diameter of 5-10 μm and a length of 0.1-0.5 mm.

7. A method for preparing a corrosion-resistant fluororubber for a screw pump according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1. Raw material pretreatment: pass the fluororubber rubber through the open mill for 3 times with the roller temperature at 40-50°C, and add hydroxy silicone oil to mix; S2. Mixing process: S201, plasticizing the fluororubber raw rubber in an internal mixer for 10-15 minutes; S202, adding fumed silica, magnesium oxide, polytetrafluoroethylene powder, carbon fiber chopped strands, bisphenol AF and benzyl triphenyl phosphonium chloride to an internal mixer in sequence to ensure uniform mixing of the rubber materials; S3, preforming process, forming the mixed rubber into a tubular blank through an extruder; S4, vulcanization process: S401, the first vulcanization, using a flat vulcanizing machine for vulcanization and molding, the vulcanization temperature is controlled at 170 ℃ -180 ℃, the vulcanization time is 20-40 minutes; S402, the second vulcanization, during which appropriate pressure is applied to ensure that the fluororubber is fully cross-linked, and the temperature is gradually raised to 230°C and kept at this temperature for 24 hours to improve the density and performance stability of the stator; S5. Molding process: compression molding or injection molding is used to process the vulcanized fluororubber into the screw pump stator. The mold temperature and molding pressure are controlled during the molding process to ensure the dimensional accuracy and performance consistency of the screw pump stator.

8. The method for preparing corrosion-resistant fluororubber for a screw pump according to claim 7, characterized in that: In step S201, the speed of the internal mixer is 30-40 r / min, and the plasticizing temperature of the internal mixer is controlled at 60°C-70°C; In step S202, the mixing temperature is controlled at 70°C-80°C and the mixing time is 20-30 minutes to ensure that the rubber materials are evenly mixed.

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