A high temperature and corrosion resistant food grade gasket material and preparation method thereof

Abstract

The present application relates to the technical field of rubber preparation, and specifically discloses a food-grade gasket material that is resistant to high temperature and corrosion and a preparation method thereof. The food-grade gasket material comprises raw materials: an EPDM rubber blend, a functional filler, an activator, a plasticizer, an antioxidant, a softener, a vulcanizer, and a cross-linking agent; the preparation method thereof is as follows: S1, plasticizing the EPDM rubber blend to obtain raw rubber; S2, adding an activator, a plasticizer, an antioxidant, and a softener to the raw rubber to obtain a first mixed product, and adding a functional filler to obtain a second mixed product; S3, mixing the second mixed product with a vulcanizer and a cross-linking agent to prepare a final rubber mixed rubber; S4, heating and pressurizing the rubber mixed rubber for vulcanization, cooling, and shaping to obtain a food-grade gasket material that is resistant to high temperature and corrosion; the food-grade gasket material prepared in the present application has excellent performance in thermal stability, mechanical strength, corrosion resistance, wear resistance, and hardness, and meets a variety of application requirements.

Description

Technical Field

[0001] The present application relates to the technical field of rubber preparation, and more specifically, to a high temperature and corrosion resistant food grade gasket material and a preparation method thereof. Background Art

[0002] As a high-efficiency heat exchange equipment, plate heat exchanger is an ideal equipment for liquid-liquid and liquid-steam heat exchange. It has the characteristics of high heat exchange efficiency, low heat loss, compact and lightweight structure, small footprint, wide application, long service life, etc. It is widely used in chemical, food, pharmaceutical, aerospace, energy and other fields. The sealing gasket of plate heat exchanger is one of the core components of plate heat exchanger. It not only plays the role of sealing medium and guiding flow, but also must be able to withstand extreme temperature and corrosive environment. However, the existing gasket materials often show performance limitations when facing high temperature, corrosive media and frequent cleaning and disinfection cycles.

[0003] Ethylene propylene diene monomer (EPDM) gasket is one of the commonly used gaskets for plate heat exchangers, and is mainly used for high-temperature sterilization in the fields of hot water, water vapor, edible beverages, milk, edible oil, etc. Although EPDM gaskets have good performance in high temperature resistance and chemical corrosion resistance, they still have the following shortcomings: (1) During long-term use, especially during frequent disassembly and cleaning, the mechanical strength and wear resistance of EPDM gaskets are insufficient, resulting in a decrease in sealing performance and the need for frequent replacement; (2) EPDM gaskets have poor tolerance to oil media (especially mineral oil and edible oil), and are prone to swelling and degradation in oil media, resulting in sealing failure and possibly affecting food safety; (3) Under long-term high temperature environment, EPDM gaskets are prone to thermal aging, resulting in hardening and cracking of the material, thereby affecting the sealing performance and service life. With the continuous development of science and technology and the continuous improvement of people's living standards, more and more attention is paid to food safety. The problems existing in existing EPDM gaskets are no longer sufficient to meet current production requirements. Based on the above statements, the present invention provides a high temperature and corrosion resistant food-grade gasket material and a preparation method thereof. Summary of the invention

[0004] In order to solve the technical problems mentioned in the background technology, the present application provides a high temperature resistant and corrosion resistant food grade gasket material and a preparation method thereof.

[0005] In the first aspect, the present application provides a food-grade gasket material that is resistant to high temperature and corrosion, and adopts the following technical solution:

[0006] A high temperature resistant and corrosion resistant food grade gasket material comprises the following raw materials in parts by weight: 90-110 parts of EPDM rubber blend, 70-90 parts of functional filler, 4-6 parts of activator, 1-3 parts of plasticizer, 1-3 parts of antioxidant, 2-3 parts of softener, 3-5 parts of vulcanizer and 0.5-2 parts of cross-linking agent.

[0007] Preferably, the high temperature and corrosion resistant food-grade gasket material comprises the following raw materials in parts by weight: 95-105 parts of EPDM rubber blend, 75-85 parts of functional filler, 4.5-5.5 parts of activator, 1.5-2.5 parts of plasticizer, 1.5-2.5 parts of antioxidant, 2.2-2.8 parts of softener, 3.5-4.5 parts of vulcanizer, and 1-1.6 parts of cross-linking agent.

[0008] Preferably, the high temperature and corrosion resistant food-grade gasket material comprises the following raw materials in parts by weight: 100 parts of EPDM rubber blend, 80 parts of functional filler, 5 parts of activator, 2 parts of plasticizer, 2 parts of antioxidant, 2.5 parts of softener, 4 parts of vulcanizer, and 1.2 parts of cross-linking agent.

[0009] Preferably, the EPDM rubber blend is obtained by mixing EPDM rubber A, EPDM rubber B and polyethylene.

[0010] Preferably, the mass ratio of the EPDM rubber A, EPDM rubber B and polyethylene is 1:1-1.5:0.2-0.3, wherein the Mooney viscosity of the EPDM rubber A is 20-30MU, the Mooney viscosity of the EPDM rubber B is 70-90MU, the polyethylene is low-density polyethylene, and the melt flow rate of the low-density polyethylene is 4-8g / 10min.

[0011] Preferably, the activator is zinc oxide and octadecyl acrylate in a mass ratio of 8-12:0.3-0.8.

[0012] Preferably, the plasticizer is polyethylene glycol-4000.

[0013] Preferably, the antioxidant is a mixture of antioxidant MB and antioxidant RD in a mass ratio of 0.5-1.5:0.7-1.

[0014] Preferably, the softener is paraffin oil 6030.

[0015] Preferably, the vulcanizing agent is diisopropyl di-tert-butyl peroxide.

[0016] Preferably, the auxiliary cross-linking agent is triallyl isocyanurate.

[0017] Preferably, the functional filler is prepared by the following method:

[0018] (1) Add carbon black and barium sulfate to water at a temperature of 50-70°C, stir and mix, then add silane coupling agent, and ultrasonically disperse for 1-2 hours to obtain a suspension;

[0019] (2) Add sodium silicate and a cross-linking agent to the above suspension, raise the temperature to 60-80°C, continue ultrasonication for 1-2 hours, filter, and dry to obtain a functional filler.

[0020] Preferably, in step (1), the mass ratio of carbon black, barium sulfate, water and silane coupling agent is 24-28:4-6:100:1-2.

[0021] Preferably, the carbon black is a mixture of N550, N660 and N990 in a mass ratio of 45-55:15-25:5-15.

[0022] Preferably, the silane coupling agent is γ-aminopropyltriethoxysilane.

[0023] Preferably, in step (2), the mass ratio of the suspension, sodium silicate and cross-linking agent is 50-60:1-3:0.5-1.

[0024] Preferably, the cross-linking agent is 1,6-hexanediamine and L-lysine in a mass ratio of 4-5:1-2.

[0025] In the second aspect, the present application provides a method for preparing a high temperature resistant and corrosion resistant food grade gasket material, using the following technical solution:

[0026] A method for preparing a high temperature resistant and corrosion resistant food grade gasket material, comprising the following preparation steps:

[0027] S1. Add EPDM rubber blend into a closed rubber mixer, plasticize, and mix evenly to obtain raw rubber;

[0028] S2, adding an activator, a plasticizer, an antioxidant, and a softener to the raw rubber of S1 for a first mixing to obtain a first mixing product, adding a functional filler to the first mixing product, and uniformly mixing to obtain a second mixing product;

[0029] S3, in an open rubber mixer, mixing the second mixed product obtained in S2 with a vulcanizing agent and a co-crosslinking agent to prepare a final rubber mix;

[0030] S4, the rubber compound in S3 is vulcanized by heating and pressurizing in a vulcanizer, cooled, and shaped to obtain a high temperature resistant and corrosion resistant food grade gasket material.

[0031] Preferably, the temperature of the closed rubber mixer in S1 is 85-100° C., the plasticizing speed is 40-50 rpm, and the plasticizing time is 30s-60s.

[0032] Preferably, the mixing temperature of the first mixed product in S2 is 130-150°C, the mixing speed is 50-60rpm, and the mixing time is 120-180s; the mixing temperature of the second mixed product is 140-160°C, the mixing speed is 70-80rpm, and the mixing time is 180-300s.

[0033] Preferably, in S3, the mixing temperature is 150-160° C., the mixing speed is 60-80 rpm, and the mixing time is 120-180 s.

[0034] Preferably, in S4, the vulcanization temperature is 150-180° C., the vulcanization time is 10-30 min, and the vulcanization pressure is 15-20 MPa.

[0035] In summary, this application has the following beneficial effects:

[0036] The present application utilizes two EPDM rubbers in combination to enhance the interaction between molecules and improve the physical and mechanical properties of the composite material, such as tensile strength, tear strength, and wear resistance. The addition of polyethylene can improve the processing performance of the EPDM rubber and can further enhance the strength, durability, flexibility, and corrosion resistance of the EPDM rubber, which helps to improve the flexibility and shock absorption effect of rubber products, making them more suitable for use in different application scenarios.

[0037] The present application utilizes a silane coupling agent to treat carbon black and barium sulfate, and then adds sodium silicate and a cross-linking agent to react to obtain a functional filler, thereby improving the dispersibility and stability of the filler in the rubber matrix, reducing the occurrence of filler agglomeration, and significantly improving the comprehensive properties of EPDM rubber products such as strength, hardness, wear resistance, aging resistance, heat resistance, acid and alkali resistance, etc. By adding different types of carbon black, the material has the advantages of large specific surface area and high structure. The carbon black with a large specific surface area can form a strong interaction with the rubber molecular chain, significantly improving the tensile strength, tear strength and wear resistance of EPDM products. The carbon black with high structure can form more occluded rubber, further improving the tensile stress and hardness of the vulcanized rubber; the three-dimensional network structure formed by the combined action of sodium silicate and the cross-linking agent can further enhance the mechanical properties and stability of the functional filler, thereby improving the cross-linking density of the rubber, enhancing its strength and durability, and making the rubber more tough and tear-resistant.

[0038] The present application uses 1,6-hexanediamine and L-lysine as common cross-linking agents. 1,6-hexanediamine provides linear diamino cross-linking, and L-lysine provides cross-linking points with side chains, which can form a more stable and functionally rich cross-linking network, promote interface bonding, and further improve the mechanical strength, thermal stability and dispersibility of EPDM rubber products, showing excellent comprehensive performance and meeting various application requirements. DETAILED DESCRIPTION

[0039] The present application is further described in detail below with reference to the embodiments.

[0040] Embodiment 1-3 provides a high temperature resistant and corrosion resistant food grade gasket material and a preparation method thereof.

[0041] Example 1

[0042] A high temperature and corrosion resistant food grade gasket material comprises the following raw materials in parts by weight: 90 parts of EPDM rubber blend, 70 parts of functional filler, 4 parts of activator, 1 part of plasticizer, 1 part of antioxidant, 2 parts of softener, 3 parts of vulcanizer and 0.5 parts of cross-linking agent.

[0043] The EPDM rubber blend is obtained by mixing EPDM Keltan® 2650C (Mooney viscosity is 25MU), EPDM Keltan® 8550C (Mooney viscosity is 80MU) and low-density polyethylene in a mass ratio of 1:1:0.2, and the melt flow rate of the low-density polyethylene is 7g / 10min.

[0044] Functional fillers are prepared by the following method:

[0045] (1) Add carbon black and barium sulfate to water at a temperature of 50°C, control the stirring speed to 200 rpm, stir and mix for 10 minutes, then add γ-aminopropyltriethoxysilane, and ultrasonically disperse for 1 hour. Control the ultrasonic power to 320 W and the ultrasonic frequency to 24 kHz to obtain a suspension, wherein the mass ratio of carbon black, barium sulfate, water, and silane coupling agent is 24:4:100:1, and the carbon black is a mixture of N550, N660, and N990 in a mass ratio of 45:15:5;

[0046] (2) Add sodium silicate and a cross-linking agent to the above suspension, raise the temperature to 70°C, continue ultrasonication for 1 hour, filter, and dry at 80°C to obtain a functional filler; wherein the mass ratio of the suspension, sodium silicate and the cross-linking agent is 50:1:0.5, and the cross-linking agent is 1.6-hexanediamine and L-lysine in a mass ratio of 4:1.

[0047] Among them, the activator is zinc oxide and octadecyl acrylate in a mass ratio of 8:0.3, the plasticizer is polyethylene glycol-4000, the antioxidant is a mixture of antioxidant MB and antioxidant RD in a mass ratio of 0.5:0.7, the softener is paraffin oil 6030, the vulcanizer is di-tert-butyl peroxide diisopropylbenzene, and the co-crosslinking agent is triallyl isocyanurate.

[0048] A method for preparing a high temperature resistant and corrosion resistant food grade gasket material, comprising the following preparation steps:

[0049] S1. Add EPDM rubber blend into a closed rubber mixer, control the temperature of the closed rubber mixer to 85°C, the plasticizing speed to 40 rpm, the plasticizing time to 30 s, and mix well to obtain raw rubber;

[0050] S2, adding an activator, a plasticizer, an antioxidant, and a softener to the S1 raw rubber for a first mixing to obtain a first mixing product, adding a functional filler to the first mixing product, and uniformly mixing to obtain a second mixing product; controlling the mixing temperature of the first mixing product to be 130° C., the mixing speed to be 50 rpm, and the mixing time to be 120 s; controlling the mixing temperature of the second mixing product to be 140° C., the mixing speed to be 70 rpm, and the mixing time to be 180 s;

[0051] S3, in an open rubber mixer, mixing the second mixed product obtained in S2 with a vulcanizing agent and a cross-linking agent to prepare a final rubber compound; controlling the mixing temperature to be 150° C., the mixing speed to be 60 rpm, and the mixing time to be 120 s;

[0052] S4. The rubber compound in S3 is heated and pressurized for vulcanization at a vulcanization temperature of 150° C., a vulcanization time of 10 min, and a vulcanization pressure of 15 MPa. The mixture is cooled and shaped to obtain a high temperature resistant and corrosion resistant food grade gasket material.

[0053] Example 2

[0054] A high temperature and corrosion resistant food grade gasket material comprises the following raw materials in parts by weight: 110 parts of EPDM rubber blend, 80 parts of functional filler, 5 parts of activator, 2 parts of plasticizer, 2 parts of antioxidant, 2.5 parts of softener, 45 parts of vulcanizer and 1.4 parts of cross-linking agent.

[0055] The EPDM rubber blend is obtained by mixing EPDM Keltan® 2650C (Mooney viscosity is 25MU), EPDM Keltan® 8550C (Mooney viscosity is 80MU) and low-density polyethylene in a mass ratio of 1:1.25:0.25, and the melt flow rate of the low-density polyethylene is 7 g / 10min.

[0056] Functional fillers are prepared by the following method:

[0057] (1) Add carbon black and barium sulfate to water at a temperature of 55°C, control the stirring speed to 250 rpm, stir and mix for 15 minutes, then add γ-aminopropyltriethoxysilane, and perform ultrasonic dispersion for 1.5 hours. Control the ultrasonic power to 340 W and the ultrasonic frequency to 26 kHz to obtain a suspension, wherein the mass ratio of carbon black, barium sulfate, water, and silane coupling agent is 26:5:100:1.5, and the carbon black is a mixture of N550, N660, and N990 in a mass ratio of 50:20:10;

[0058] (2) Add sodium silicate and a cross-linking agent to the above suspension, raise the temperature to 75°C, continue ultrasonication for 1.5 hours, filter, and dry at 80°C to obtain a functional filler; wherein the mass ratio of the suspension, sodium silicate, and cross-linking agent is 55:2:0.8, and the cross-linking agent is 1,6-hexanediamine and L-lysine in a mass ratio of 4.5:1.5.

[0059] Among them, the activator is zinc oxide and octadecyl acrylate in a mass ratio of 10:0.5, the plasticizer is polyethylene glycol-4000, the antioxidant is a mixture of antioxidant MB and antioxidant RD in a mass ratio of 1:0.85, the softener is paraffin oil 6030, the vulcanizer is di-tert-butyl peroxide diisopropylbenzene, and the co-crosslinking agent is triallyl isocyanurate.

[0060] A method for preparing a high temperature resistant and corrosion resistant food grade gasket material, comprising the following preparation steps:

[0061] S1. Add EPDM rubber blend into a closed rubber mixer, control the temperature of the closed rubber mixer to 92°C, the plasticizing speed to 45 rpm, the plasticizing time to 45 s, and mix well to obtain raw rubber;

[0062] S2, adding an activator, a plasticizer, an antioxidant, and a softener to the S1 raw rubber for a first mixing to obtain a first mixing product, adding a functional filler to the first mixing product, and uniformly mixing to obtain a second mixing product; controlling the mixing temperature of the first mixing product to be 140° C., the mixing speed to be 55 rpm, and the mixing time to be 150 s; controlling the mixing temperature of the second mixing product to be 150° C., the mixing speed to be 75 rpm, and the mixing time to be 240 s;

[0063] S3, in an open rubber mixer, mixing the second mixed product obtained in S2 with a vulcanizing agent and a cross-linking agent to prepare a final rubber mix; controlling the mixing temperature to be 155° C., the mixing speed to be 70 rpm, and the mixing time to be 150 s;

[0064] S4. The rubber compound in S3 is heated and pressurized in a vulcanizer for vulcanization at a vulcanization temperature of 175°C, a vulcanization time of 20 min, and a vulcanization pressure of 18 MPa. The mixture is cooled and shaped to obtain a high temperature resistant and corrosion resistant food grade gasket material.

[0065] Example 3

[0066] A high temperature and corrosion resistant food grade gasket material comprises the following raw materials in parts by weight: 110 parts of EPDM rubber blend, 90 parts of functional filler, 6 parts of activator, 3 parts of plasticizer, 3 parts of antioxidant, 3 parts of softener, 5 parts of vulcanizer and 2 parts of cross-linking aid.

[0067] The EPDM rubber blend is obtained by mixing EPDM Keltan® 2650C (Mooney viscosity is 25MU), EPDM Keltan® 8550C (Mooney viscosity is 80MU) and low-density polyethylene in a mass ratio of 1:1.5:0.3, and the melt flow rate of the low-density polyethylene is 7g / 10min.

[0068] Functional fillers are prepared by the following method:

[0069] (1) Add carbon black and barium sulfate to water at a temperature of 60°C, control the stirring speed to 300 rpm, stir and mix for 20 minutes, then add γ-aminopropyltriethoxysilane, and ultrasonically disperse for 2 hours. Control the ultrasonic power to 360 W and the ultrasonic frequency to 32 kHz to obtain a suspension, wherein the mass ratio of carbon black, barium sulfate, water, and silane coupling agent is 28:6:100:2, and the carbon black is a mixture of N550, N660, and N990 in a mass ratio of 55:25:15;

[0070] (2) Add sodium silicate and a cross-linking agent to the above suspension, raise the temperature to 80°C, continue ultrasonication for 2 hours, filter, and dry at 80°C to obtain a functional filler; wherein the mass ratio of the suspension, sodium silicate and the cross-linking agent is 60:3:1, and the cross-linking agent is 1.6-hexanediamine and L-lysine in a mass ratio of 5:2.

[0071] Among them, the activator is zinc oxide and octadecyl acrylate in a mass ratio of 12:0.8, the plasticizer is polyethylene glycol-4000, the antioxidant is a mixture of antioxidant MB and antioxidant RD in a mass ratio of 1.5:1, the softener is paraffin oil 6030, the vulcanizer is di-tert-butyl peroxide diisopropylbenzene, and the co-crosslinking agent is triallyl isocyanurate.

[0072] A method for preparing a high temperature resistant and corrosion resistant food grade gasket material, comprising the following preparation steps:

[0073] S1. Add EPDM rubber blend into a closed rubber mixer, control the temperature of the closed rubber mixer to 100°C, the plasticizing speed to 50 rpm, the plasticizing time to 60 s, and mix well to obtain raw rubber;

[0074] S2, adding an activator, a plasticizer, an antioxidant, and a softener to the raw rubber of S1 for a first mixing to obtain a first mixing product, adding a functional filler to the first mixing product, and uniformly mixing to obtain a second mixing product; controlling the mixing temperature of the first mixing product to be 150° C., the mixing speed to be 60 rpm, and the mixing time to be 180 s; controlling the mixing temperature of the second mixing product to be 160° C., the mixing speed to be 80 rpm, and the mixing time to be 300 s;

[0075] S3, in an open rubber mixer, mixing the second mixed product obtained in S2 with a vulcanizing agent and a cross-linking agent to prepare a final rubber mix; controlling the mixing temperature to be 160° C., the mixing speed to be 80 rpm, and the mixing time to be 180 s;

[0076] S4. The rubber compound in S3 is heated and pressurized in a vulcanizer for vulcanization at a vulcanization temperature of 180°C, a vulcanization time of 30 min, and a vulcanization pressure of 20 MPa. The mixture is cooled and shaped to obtain a high temperature resistant and corrosion resistant food grade gasket material.

[0077] In order to verify the comprehensive performance of the high temperature resistant and corrosion resistant food grade gasket material prepared in Examples 1-3 of the present application, the applicant set up comparative examples 1-10, which are as follows:

[0078] Comparative Example 1

[0079] A high temperature and corrosion resistant food grade gasket material comprises the following raw materials in parts by weight: 90 parts of EPDM rubber blend, 70 parts of functional filler, 4 parts of activator, 1 part of plasticizer, 1 part of antioxidant, 2 parts of softener, 3 parts of vulcanizer and 0.5 parts of cross-linking agent.

[0080] The EPDM rubber blend consists of EPDM Keltan® 2650C (Mooney viscosity is 25MU) and EPDM Keltan® 8550C (Mooney viscosity is 80MU) in a mass ratio of 1:1.

[0081] Functional fillers are prepared by the following method:

[0082] (1) Add carbon black and barium sulfate to water at a temperature of 50°C, control the stirring speed to 200 rpm, stir and mix for 10 minutes, then add γ-aminopropyltriethoxysilane, and ultrasonically disperse for 1 hour. Control the ultrasonic power to 320 W and the ultrasonic frequency to 24 kHz to obtain a suspension, wherein the mass ratio of carbon black, barium sulfate, water, and silane coupling agent is 24:4:100:1, and the carbon black is a mixture of N550, N660, and N990 in a mass ratio of 45:15:5;

[0083] (2) Add sodium silicate and a cross-linking agent to the above suspension, raise the temperature to 70°C, continue ultrasonication for 1 hour, filter, and dry at 80°C to obtain a functional filler; wherein the mass ratio of the suspension, sodium silicate and the cross-linking agent is 50:1:0.5, and the cross-linking agent is 1.6-hexanediamine and L-lysine in a mass ratio of 4:1.

[0084] Among them, the activator is zinc oxide and octadecyl acrylate in a mass ratio of 8:0.3, the plasticizer is polyethylene glycol-4000, the antioxidant is a mixture of antioxidant MB and antioxidant RD in a mass ratio of 0.5:0.7, the softener is paraffin oil 6030, the vulcanizer is di-tert-butyl peroxide diisopropylbenzene, and the co-crosslinking agent is triallyl isocyanurate.

[0085] A method for preparing a high temperature resistant and corrosion resistant food grade gasket material, comprising the following preparation steps:

[0086] S1. Add EPDM rubber blend into a closed rubber mixer, control the temperature of the closed rubber mixer to 85°C, the plasticizing speed to 40 rpm, the plasticizing time to 30 s, and mix well to obtain raw rubber;

[0087] S2, adding an activator, a plasticizer, an antioxidant, and a softener to the S1 raw rubber for a first mixing to obtain a first mixing product, adding a functional filler to the first mixing product, and uniformly mixing to obtain a second mixing product; controlling the mixing temperature of the first mixing product to be 130° C., the mixing speed to be 50 rpm, and the mixing time to be 120 s; controlling the mixing temperature of the second mixing product to be 140° C., the mixing speed to be 70 rpm, and the mixing time to be 180 s;

[0088] S3, in an open rubber mixer, mixing the second mixed product obtained in S2 with a vulcanizing agent and a cross-linking agent to prepare a final rubber compound; controlling the mixing temperature to be 150° C., the mixing speed to be 60 rpm, and the mixing time to be 120 s;

[0089] S4. The rubber compound in S3 is heated and pressurized for vulcanization at a vulcanization temperature of 150° C., a vulcanization time of 10 min, and a vulcanization pressure of 15 MPa. The mixture is cooled and shaped to obtain a high temperature resistant and corrosion resistant food grade gasket material.

[0090] Comparative Example 2

[0091] A high temperature and corrosion resistant food grade gasket material comprises the following raw materials in parts by weight: 90 parts of EPDM rubber blend, 70 parts of functional filler, 4 parts of activator, 1 part of plasticizer, 1 part of antioxidant, 2 parts of softener, 3 parts of vulcanizer and 0.5 parts of cross-linking agent.

[0092] The EPDM rubber blend is obtained by mixing EPDM Keltan® 2650C (Mooney viscosity is 25MU), EPDM Keltan® 8550C (Mooney viscosity is 80MU) and high-density polyethylene in a mass ratio of 1:1:0.2, and the melt flow rate of the high-density polyethylene is 7g / 10min.

[0093] Functional fillers are prepared by the following method:

[0094] (1) Add carbon black and barium sulfate to water at a temperature of 50°C, control the stirring speed to 200 rpm, stir and mix for 10 minutes, then add γ-aminopropyltriethoxysilane, and ultrasonically disperse for 1 hour. Control the ultrasonic power to 320 W and the ultrasonic frequency to 24 kHz to obtain a suspension, wherein the mass ratio of carbon black, barium sulfate, water, and silane coupling agent is 24:4:100:1, and the carbon black is a mixture of N550, N660, and N990 in a mass ratio of 45:15:5;

[0095] (2) Add sodium silicate and a cross-linking agent to the above suspension, raise the temperature to 70°C, continue ultrasonication for 1 hour, filter, and dry at 80°C to obtain a functional filler; wherein the mass ratio of the suspension, sodium silicate and the cross-linking agent is 50:1:0.5, and the cross-linking agent is 1.6-hexanediamine and L-lysine in a mass ratio of 4:1.

[0096] Among them, the activator is zinc oxide and octadecyl acrylate in a mass ratio of 8:0.3, the plasticizer is polyethylene glycol-4000, the antioxidant is a mixture of antioxidant MB and antioxidant RD in a mass ratio of 0.5:0.7, the softener is paraffin oil 6030, the vulcanizer is di-tert-butyl peroxide diisopropylbenzene, and the co-crosslinking agent is triallyl isocyanurate.

[0097] A method for preparing a high temperature resistant and corrosion resistant food grade gasket material, comprising the following preparation steps:

[0098] S1. Add EPDM rubber blend into a closed rubber mixer, control the temperature of the closed rubber mixer to 85°C, the plasticizing speed to 40 rpm, the plasticizing time to 30 s, and mix well to obtain raw rubber;

[0099] S2, adding an activator, a plasticizer, an antioxidant, and a softener to the S1 raw rubber for a first mixing to obtain a first mixing product, adding a functional filler to the first mixing product, and uniformly mixing to obtain a second mixing product; controlling the mixing temperature of the first mixing product to be 130° C., the mixing speed to be 50 rpm, and the mixing time to be 120 s; controlling the mixing temperature of the second mixing product to be 140° C., the mixing speed to be 70 rpm, and the mixing time to be 180 s;

[0100] S3, in an open rubber mixer, mixing the second mixed product obtained in S2 with a vulcanizing agent and a cross-linking agent to prepare a final rubber compound; controlling the mixing temperature to be 150° C., the mixing speed to be 60 rpm, and the mixing time to be 120 s;

[0101] S4. The rubber compound in S3 is heated and pressurized for vulcanization at a vulcanization temperature of 150° C., a vulcanization time of 10 min, and a vulcanization pressure of 15 MPa. The mixture is cooled and shaped to obtain a high temperature resistant and corrosion resistant food grade gasket material.

[0102] Comparative Example 3

[0103] A high temperature and corrosion resistant food grade gasket material comprises the following raw materials in parts by weight: 90 parts of EPDM rubber blend, 70 parts of functional filler, 4 parts of activator, 1 part of plasticizer, 1 part of antioxidant, 2 parts of softener, 3 parts of vulcanizer and 0.5 parts of cross-linking agent.

[0104] The EPDM rubber blend is obtained by mixing EPDM Keltan® 2650C (Mooney viscosity is 25MU) and low-density polyethylene in a mass ratio of 2:0.2, and the melt flow rate of the low-density polyethylene is 7g / 10min.

[0105] Functional fillers are prepared by the following method:

[0106] (1) Add carbon black and barium sulfate to water at a temperature of 50°C, control the stirring speed to 200 rpm, stir and mix for 10 minutes, then add γ-aminopropyltriethoxysilane, and ultrasonically disperse for 1 hour. Control the ultrasonic power to 320 W and the ultrasonic frequency to 24 kHz to obtain a suspension, wherein the mass ratio of carbon black, barium sulfate, water, and silane coupling agent is 24:4:100:1, and the carbon black is a mixture of N550, N660, and N990 in a mass ratio of 45:15:5;

[0107] (2) Add sodium silicate and a cross-linking agent to the above suspension, raise the temperature to 70°C, continue ultrasonication for 1 hour, filter, and dry at 80°C to obtain a functional filler; wherein the mass ratio of the suspension, sodium silicate and the cross-linking agent is 50:1:0.5, and the cross-linking agent is 1.6-hexanediamine and L-lysine in a mass ratio of 4:1.

[0108] Among them, the activator is zinc oxide and octadecyl acrylate in a mass ratio of 8:0.3, the plasticizer is polyethylene glycol-4000, the antioxidant is a mixture of antioxidant MB and antioxidant RD in a mass ratio of 0.5:0.7, the softener is paraffin oil 6030, the vulcanizer is di-tert-butyl peroxide diisopropylbenzene, and the co-crosslinking agent is triallyl isocyanurate.

[0109] A method for preparing a high temperature resistant and corrosion resistant food grade gasket material, comprising the following preparation steps:

[0110] S1. Add EPDM rubber blend into a closed rubber mixer, control the temperature of the closed rubber mixer to 85°C, the plasticizing speed to 40 rpm, the plasticizing time to 30 s, and mix well to obtain raw rubber;

[0111] S2, adding an activator, a plasticizer, an antioxidant, and a softener to the S1 raw rubber for a first mixing to obtain a first mixing product, adding a functional filler to the first mixing product, and uniformly mixing to obtain a second mixing product; controlling the mixing temperature of the first mixing product to be 130° C., the mixing speed to be 50 rpm, and the mixing time to be 120 s; controlling the mixing temperature of the second mixing product to be 140° C., the mixing speed to be 70 rpm, and the mixing time to be 180 s;

[0112] S3, in an open rubber mixer, mixing the second mixed product obtained in S2 with a vulcanizing agent and a cross-linking agent to prepare a final rubber compound; controlling the mixing temperature to be 150° C., the mixing speed to be 60 rpm, and the mixing time to be 120 s;

[0113] S4. The rubber compound in S3 is heated and pressurized for vulcanization at a vulcanization temperature of 150° C., a vulcanization time of 10 min, and a vulcanization pressure of 15 MPa. The mixture is cooled and shaped to obtain a high temperature resistant and corrosion resistant food grade gasket material.

[0114] Comparative Example 4

[0115] A high temperature and corrosion resistant food grade gasket material comprises the following raw materials in parts by weight: 90 parts of EPDM rubber blend, 70 parts of functional filler, 4 parts of activator, 1 part of plasticizer, 1 part of antioxidant, 2 parts of softener, 3 parts of vulcanizer and 0.5 parts of cross-linking agent.

[0116] The EPDM rubber blend is obtained by mixing EPDM Keltan® 8550C (Mooney viscosity is 80MU) and low-density polyethylene in a mass ratio of 2:0.2, and the melt flow rate of the low-density polyethylene is 7g / 10min.

[0117] Functional fillers are prepared by the following method:

[0118] (1) Add carbon black and barium sulfate to water at a temperature of 50°C, control the stirring speed to 200 rpm, stir and mix for 10 minutes, then add γ-aminopropyltriethoxysilane, and ultrasonically disperse for 1 hour. Control the ultrasonic power to 320 W and the ultrasonic frequency to 24 kHz to obtain a suspension, wherein the mass ratio of carbon black, barium sulfate, water, and silane coupling agent is 24:4:100:1, and the carbon black is a mixture of N550, N660, and N990 in a mass ratio of 45:15:5;

[0119] (2) Add sodium silicate and a cross-linking agent to the above suspension, raise the temperature to 70°C, continue ultrasonication for 1 hour, filter, and dry at 80°C to obtain a functional filler; wherein the mass ratio of the suspension, sodium silicate and the cross-linking agent is 50:1:0.5, and the cross-linking agent is 1.6-hexanediamine and L-lysine in a mass ratio of 4:1.

[0120] Among them, the activator is zinc oxide and octadecyl acrylate in a mass ratio of 8:0.3, the plasticizer is polyethylene glycol-4000, the antioxidant is a mixture of antioxidant MB and antioxidant RD in a mass ratio of 0.5:0.7, the softener is paraffin oil 6030, the vulcanizer is di-tert-butyl peroxide diisopropylbenzene, and the co-crosslinking agent is triallyl isocyanurate.

[0121] A method for preparing a high temperature resistant and corrosion resistant food grade gasket material, comprising the following preparation steps:

[0122] S1. Add EPDM rubber blend into a closed rubber mixer, control the temperature of the closed rubber mixer to 85°C, the plasticizing speed to 40 rpm, the plasticizing time to 30 s, and mix well to obtain raw rubber;

[0123] S2, adding an activator, a plasticizer, an antioxidant, and a softener to the S1 raw rubber for a first mixing to obtain a first mixing product, adding a functional filler to the first mixing product, and uniformly mixing to obtain a second mixing product; controlling the mixing temperature of the first mixing product to be 130° C., the mixing speed to be 50 rpm, and the mixing time to be 120 s; controlling the mixing temperature of the second mixing product to be 140° C., the mixing speed to be 70 rpm, and the mixing time to be 180 s;

[0124] S3, in an open rubber mixer, mixing the second mixed product obtained in S2 with a vulcanizing agent and a cross-linking agent to prepare a final rubber compound; controlling the mixing temperature to be 150° C., the mixing speed to be 60 rpm, and the mixing time to be 120 s;

[0125] S4. The rubber compound in S3 is heated and pressurized for vulcanization at a vulcanization temperature of 150° C., a vulcanization time of 10 min, and a vulcanization pressure of 15 MPa. The mixture is cooled and shaped to obtain a high temperature resistant and corrosion resistant food grade gasket material.

[0126] Comparative Example 5

[0127] A high temperature and corrosion resistant food grade gasket material comprises the following raw materials in parts by weight: 90 parts of EPDM rubber blend, 70 parts of functional filler, 4 parts of activator, 1 part of plasticizer, 1 part of antioxidant, 2 parts of softener, 3 parts of vulcanizer and 0.5 parts of cross-linking agent.

[0128] The EPDM rubber blend is obtained by mixing EPDM Keltan® 2650C (Mooney viscosity is 25MU), EPDM Keltan® 8550C (Mooney viscosity is 80MU) and low-density polyethylene in a mass ratio of 1:1:0.2, and the melt flow rate of the low-density polyethylene is 7g / 10min.

[0129] Functional fillers are prepared by the following method:

[0130] (1) Add carbon black N550 and barium sulfate to water at a temperature of 50°C, control the stirring speed to 200 rpm, stir and mix for 10 minutes, then add γ-aminopropyltriethoxysilane, and ultrasonically disperse for 1 hour. Control the ultrasonic power to 320 W and the ultrasonic frequency to 24 kHz to obtain a suspension, wherein the mass ratio of carbon black N550, barium sulfate, water, and silane coupling agent is 24:4:100:1;

[0131] (2) Add sodium silicate and a cross-linking agent to the above suspension, raise the temperature to 70°C, continue ultrasonication for 1 hour, filter, and dry at 80°C to obtain a functional filler; wherein the mass ratio of the suspension, sodium silicate and the cross-linking agent is 50:1:0.5, and the cross-linking agent is 1.6-hexanediamine and L-lysine in a mass ratio of 4:1.

[0132] Among them, the activator is zinc oxide and octadecyl acrylate in a mass ratio of 8:0.3, the plasticizer is polyethylene glycol-4000, the antioxidant is a mixture of antioxidant MB and antioxidant RD in a mass ratio of 0.5:0.7, the softener is paraffin oil 6030, the vulcanizer is di-tert-butyl peroxide diisopropylbenzene, and the co-crosslinking agent is triallyl isocyanurate.

[0133] A method for preparing a high temperature resistant and corrosion resistant food grade gasket material, comprising the following preparation steps:

[0134] S1. Add EPDM rubber blend into a closed rubber mixer, control the temperature of the closed rubber mixer to 85°C, the plasticizing speed to 40 rpm, the plasticizing time to 30 s, and mix well to obtain raw rubber;

[0135] S2, adding an activator, a plasticizer, an antioxidant, and a softener to the S1 raw rubber for a first mixing to obtain a first mixing product, adding a functional filler to the first mixing product, and uniformly mixing to obtain a second mixing product; controlling the mixing temperature of the first mixing product to be 130° C., the mixing speed to be 50 rpm, and the mixing time to be 120 s; controlling the mixing temperature of the second mixing product to be 140° C., the mixing speed to be 70 rpm, and the mixing time to be 180 s;

[0136] S3, in an open rubber mixer, mixing the second mixed product obtained in S2 with a vulcanizing agent and a cross-linking agent to prepare a final rubber compound; controlling the mixing temperature to be 150° C., the mixing speed to be 60 rpm, and the mixing time to be 120 s;

[0137] S4. The rubber compound in S3 is heated and pressurized for vulcanization at a vulcanization temperature of 150° C., a vulcanization time of 10 min, and a vulcanization pressure of 15 MPa. The mixture is cooled and shaped to obtain a high temperature resistant and corrosion resistant food grade gasket material.

[0138] Comparative Example 6

[0139] A high temperature and corrosion resistant food grade gasket material comprises the following raw materials in parts by weight: 90 parts of EPDM rubber blend, 70 parts of functional filler, 4 parts of activator, 1 part of plasticizer, 1 part of antioxidant, 2 parts of softener, 3 parts of vulcanizer and 0.5 parts of cross-linking agent.

[0140] The EPDM rubber blend is obtained by mixing EPDM Keltan® 2650C (Mooney viscosity is 25MU), EPDM Keltan® 8550C (Mooney viscosity is 80MU) and low-density polyethylene in a mass ratio of 1:1:0.2, and the melt flow rate of the low-density polyethylene is 7g / 10min.

[0141] Functional fillers are prepared by the following method:

[0142] (1) Add carbon black to water at a temperature of 50°C, control the stirring speed to 200 rpm, stir and mix for 10 minutes, then add γ-aminopropyltriethoxysilane, and ultrasonically disperse for 1 hour. Control the ultrasonic power to 320 W and the ultrasonic frequency to 24 kHz to obtain a suspension, wherein the mass ratio of carbon black, water, and silane coupling agent is 28:100:1, and the carbon black is a mixture of N550, N660, and N990 in a mass ratio of 45:15:5;

[0143] (2) Add sodium silicate and a cross-linking agent to the above suspension, raise the temperature to 70°C, continue ultrasonication for 1 hour, filter, and dry at 80°C to obtain a functional filler; wherein the mass ratio of the suspension, sodium silicate and the cross-linking agent is 50:1:0.5, and the cross-linking agent is 1.6-hexanediamine and L-lysine in a mass ratio of 4:1.

[0144] Among them, the activator is zinc oxide and octadecyl acrylate in a mass ratio of 8:0.3, the plasticizer is polyethylene glycol-4000, the antioxidant is a mixture of antioxidant MB and antioxidant RD in a mass ratio of 0.5:0.7, the softener is paraffin oil 6030, the vulcanizer is di-tert-butyl peroxide diisopropylbenzene, and the co-crosslinking agent is triallyl isocyanurate.

[0145] A method for preparing a high temperature resistant and corrosion resistant food grade gasket material, comprising the following preparation steps:

[0146] S1. Add EPDM rubber blend into a closed rubber mixer, control the temperature of the closed rubber mixer to 85°C, the plasticizing speed to 40 rpm, the plasticizing time to 30 s, and mix well to obtain raw rubber;

[0147] S2, adding an activator, a plasticizer, an antioxidant, and a softener to the S1 raw rubber for a first mixing to obtain a first mixing product, adding a functional filler to the first mixing product, and uniformly mixing to obtain a second mixing product; controlling the mixing temperature of the first mixing product to be 130° C., the mixing speed to be 50 rpm, and the mixing time to be 120 s; controlling the mixing temperature of the second mixing product to be 140° C., the mixing speed to be 70 rpm, and the mixing time to be 180 s;

[0148] S3, in an open rubber mixer, mixing the second mixed product obtained in S2 with a vulcanizing agent and a cross-linking agent to prepare a final rubber compound; controlling the mixing temperature to be 150° C., the mixing speed to be 60 rpm, and the mixing time to be 120 s;

[0149] S4. The rubber compound in S3 is heated and pressurized for vulcanization at a vulcanization temperature of 150° C., a vulcanization time of 10 min, and a vulcanization pressure of 15 MPa. The mixture is cooled and shaped to obtain a high temperature resistant and corrosion resistant food grade gasket material.

[0150] Comparative Example 7

[0151] A high temperature and corrosion resistant food grade gasket material comprises the following raw materials in parts by weight: 90 parts of EPDM rubber blend, 70 parts of functional filler, 4 parts of activator, 1 part of plasticizer, 1 part of antioxidant, 2 parts of softener, 3 parts of vulcanizer and 0.5 parts of cross-linking agent.

[0152] The EPDM rubber blend is obtained by mixing EPDM Keltan® 2650C (Mooney viscosity is 25MU), EPDM Keltan® 8550C (Mooney viscosity is 80MU) and low-density polyethylene in a mass ratio of 1:1:0.2, and the melt flow rate of the low-density polyethylene is 7g / 10min.

[0153] Functional fillers are prepared by the following method:

[0154] (1) Add carbon black and barium sulfate to water at a temperature of 50°C, control the stirring speed to 200 rpm, stir and mix for 10 minutes, then add γ-aminopropyltriethoxysilane, and ultrasonically disperse for 1 hour. Control the ultrasonic power to 320 W and the ultrasonic frequency to 24 kHz to obtain a suspension, wherein the mass ratio of carbon black, barium sulfate, water, and silane coupling agent is 24:4:100:1, and the carbon black is a mixture of N550, N660, and N990 in a mass ratio of 45:15:5;

[0155] (2) Add a crosslinking agent to the above suspension, raise the temperature to 70°C, continue ultrasonication for 1 hour, filter, and dry at 80°C to obtain a functional filler; wherein the mass ratio of the suspension to the crosslinking agent is 50:0.5, and the crosslinking agent is 1.6-hexanediamine and L-lysine in a mass ratio of 4:1.

[0156] Among them, the activator is zinc oxide and octadecyl acrylate in a mass ratio of 8:0.3, the plasticizer is polyethylene glycol-4000, the antioxidant is a mixture of antioxidant MB and antioxidant RD in a mass ratio of 0.5:0.7, the softener is paraffin oil 6030, the vulcanizer is di-tert-butyl peroxide diisopropylbenzene, and the co-crosslinking agent is triallyl isocyanurate.

[0157] A method for preparing a high temperature resistant and corrosion resistant food grade gasket material, comprising the following preparation steps:

[0158] S1. Add EPDM rubber blend into a closed rubber mixer, control the temperature of the closed rubber mixer to 85°C, the plasticizing speed to 40 rpm, the plasticizing time to 30 s, and mix well to obtain raw rubber;

[0159] S2, adding an activator, a plasticizer, an antioxidant, and a softener to the S1 raw rubber for a first mixing to obtain a first mixing product, adding a functional filler to the first mixing product, and uniformly mixing to obtain a second mixing product; controlling the mixing temperature of the first mixing product to be 130° C., the mixing speed to be 50 rpm, and the mixing time to be 120 s; controlling the mixing temperature of the second mixing product to be 140° C., the mixing speed to be 70 rpm, and the mixing time to be 180 s;

[0160] S3, in an open rubber mixer, mixing the second mixed product obtained in S2 with a vulcanizing agent and a cross-linking agent to prepare a final rubber compound; controlling the mixing temperature to be 150° C., the mixing speed to be 60 rpm, and the mixing time to be 120 s;

[0161] S4. The rubber compound in S3 is heated and pressurized for vulcanization at a vulcanization temperature of 150° C., a vulcanization time of 10 min, and a vulcanization pressure of 15 MPa. The mixture is cooled and shaped to obtain a high temperature resistant and corrosion resistant food grade gasket material.

[0162] Comparative Example 8

[0163] A high temperature and corrosion resistant food grade gasket material comprises the following raw materials in parts by weight: 90 parts of EPDM rubber blend, 70 parts of functional filler, 4 parts of activator, 1 part of plasticizer, 1 part of antioxidant, 2 parts of softener, 3 parts of vulcanizer and 0.5 parts of cross-linking agent.

[0164] The EPDM rubber blend is obtained by mixing EPDM Keltan® 2650C (Mooney viscosity is 25MU), EPDM Keltan® 8550C (Mooney viscosity is 80MU) and low-density polyethylene in a mass ratio of 1:1:0.2, and the melt flow rate of the low-density polyethylene is 7g / 10min.

[0165] Functional fillers are prepared by the following method:

[0166] (1) Add carbon black and barium sulfate into water at a temperature of 50°C, control the stirring speed to 200 rpm, stir and mix for 10 minutes, and then perform ultrasonic dispersion for 1 hour, control the ultrasonic power to 320 W, and the ultrasonic frequency to 24 kHz to obtain a suspension, wherein the mass ratio of carbon black, barium sulfate and water is 24:4:100, and the carbon black is a mixture of N550, N660 and N990 in a mass ratio of 45:15:5;

[0167] (2) Add sodium silicate and a cross-linking agent to the above suspension, raise the temperature to 70°C, continue ultrasonication for 1 hour, filter, and dry at 80°C to obtain a functional filler; wherein the mass ratio of the suspension, sodium silicate and the cross-linking agent is 50:1:0.5, and the cross-linking agent is 1.6-hexanediamine and L-lysine in a mass ratio of 4:1.

[0168] Among them, the activator is zinc oxide and octadecyl acrylate in a mass ratio of 8:0.3, the plasticizer is polyethylene glycol-4000, the antioxidant is a mixture of antioxidant MB and antioxidant RD in a mass ratio of 0.5:0.7, the softener is paraffin oil 6030, the vulcanizer is di-tert-butyl peroxide diisopropylbenzene, and the co-crosslinking agent is triallyl isocyanurate.

[0169] A method for preparing a high temperature resistant and corrosion resistant food grade gasket material, comprising the following preparation steps:

[0170] S1. Add EPDM rubber blend into a closed rubber mixer, control the temperature of the closed rubber mixer to 85°C, the plasticizing speed to 40 rpm, the plasticizing time to 30 s, and mix well to obtain raw rubber;

[0171] S2, adding an activator, a plasticizer, an antioxidant, and a softener to the S1 raw rubber for a first mixing to obtain a first mixing product, adding a functional filler to the first mixing product, and uniformly mixing to obtain a second mixing product; controlling the mixing temperature of the first mixing product to be 130° C., the mixing speed to be 50 rpm, and the mixing time to be 120 s; controlling the mixing temperature of the second mixing product to be 140° C., the mixing speed to be 70 rpm, and the mixing time to be 180 s;

[0172] S3, in an open rubber mixer, mixing the second mixed product obtained in S2 with a vulcanizing agent and a cross-linking agent to prepare a final rubber compound; controlling the mixing temperature to be 150° C., the mixing speed to be 60 rpm, and the mixing time to be 120 s;

[0173] S4. The rubber compound in S3 is heated and pressurized for vulcanization at a vulcanization temperature of 150° C., a vulcanization time of 10 min, and a vulcanization pressure of 15 MPa. The mixture is cooled and shaped to obtain a high temperature resistant and corrosion resistant food grade gasket material.

[0174] Comparative Example 9

[0175] A high temperature and corrosion resistant food grade gasket material comprises the following raw materials in parts by weight: 90 parts of EPDM rubber blend, 70 parts of functional filler, 4 parts of activator, 1 part of plasticizer, 1 part of antioxidant, 2 parts of softener, 3 parts of vulcanizer and 0.5 parts of cross-linking agent.

[0176] The EPDM rubber blend is obtained by mixing EPDM Keltan® 2650C (Mooney viscosity is 25MU), EPDM Keltan® 8550C (Mooney viscosity is 80MU) and low-density polyethylene in a mass ratio of 1:1:0.2, and the melt flow rate of the low-density polyethylene is 7g / 10min.

[0177] Functional fillers are prepared by the following method:

[0178] (1) Add carbon black and barium sulfate to water at a temperature of 50°C, control the stirring speed to 200 rpm, stir and mix for 10 minutes, then add γ-aminopropyltriethoxysilane, and ultrasonically disperse for 1 hour. Control the ultrasonic power to 320 W and the ultrasonic frequency to 24 kHz to obtain a suspension, wherein the mass ratio of carbon black, barium sulfate, water, and silane coupling agent is 24:4:100:1, and the carbon black is a mixture of N550, N660, and N990 in a mass ratio of 45:15:5;

[0179] (2) Add sodium silicate and a cross-linking agent to the above suspension, raise the temperature to 70°C, continue ultrasonication for 1 hour, filter, and dry at 80°C to obtain a functional filler; wherein the mass ratio of the suspension, sodium silicate and the cross-linking agent is 50:1:0.5, and the cross-linking agent is 1,6-hexanediamine.

[0180] Among them, the activator is zinc oxide and octadecyl acrylate in a mass ratio of 8:0.3, the plasticizer is polyethylene glycol-4000, the antioxidant is a mixture of antioxidant MB and antioxidant RD in a mass ratio of 0.5:0.7, the softener is paraffin oil 6030, the vulcanizer is di-tert-butyl peroxide diisopropylbenzene, and the co-crosslinking agent is triallyl isocyanurate.

[0181] A method for preparing a high temperature resistant and corrosion resistant food grade gasket material, comprising the following preparation steps:

[0182] S1. Add EPDM rubber blend into a closed rubber mixer, control the temperature of the closed rubber mixer to 85°C, the plasticizing speed to 40 rpm, the plasticizing time to 30 s, and mix well to obtain raw rubber;

[0183] S2, adding an activator, a plasticizer, an antioxidant, and a softener to the S1 raw rubber for a first mixing to obtain a first mixing product, adding a functional filler to the first mixing product, and uniformly mixing to obtain a second mixing product; controlling the mixing temperature of the first mixing product to be 130° C., the mixing speed to be 50 rpm, and the mixing time to be 120 s; controlling the mixing temperature of the second mixing product to be 140° C., the mixing speed to be 70 rpm, and the mixing time to be 180 s;

[0184] S3, in an open rubber mixer, mixing the second mixed product obtained in S2 with a vulcanizing agent and a cross-linking agent to prepare a final rubber compound; controlling the mixing temperature to be 150° C., the mixing speed to be 60 rpm, and the mixing time to be 120 s;

[0185] S4. The rubber compound in S3 is heated and pressurized for vulcanization at a vulcanization temperature of 150° C., a vulcanization time of 10 min, and a vulcanization pressure of 15 MPa. The mixture is cooled and shaped to obtain a high temperature resistant and corrosion resistant food grade gasket material.

[0186] Comparative Example 10

[0187] A high temperature and corrosion resistant food grade gasket material comprises the following raw materials in parts by weight: 90 parts of EPDM rubber blend, 70 parts of functional filler, 4 parts of activator, 1 part of plasticizer, 1 part of antioxidant, 2 parts of softener, 3 parts of vulcanizer and 0.5 parts of cross-linking agent.

[0188] The EPDM rubber blend is obtained by mixing EPDM Keltan® 2650C (Mooney viscosity is 25MU), EPDM Keltan® 8550C (Mooney viscosity is 80MU) and low-density polyethylene in a mass ratio of 1:1:0.2, and the melt flow rate of the low-density polyethylene is 7g / 10min.

[0189] Functional fillers are prepared by the following method:

[0190] (1) Add carbon black and barium sulfate to water at a temperature of 50°C, control the stirring speed to 200 rpm, stir and mix for 10 minutes, then add γ-aminopropyltriethoxysilane, and ultrasonically disperse for 1 hour. Control the ultrasonic power to 320 W and the ultrasonic frequency to 24 kHz to obtain a suspension, wherein the mass ratio of carbon black, barium sulfate, water, and silane coupling agent is 24:4:100:1, and the carbon black is a mixture of N550, N660, and N990 in a mass ratio of 45:15:5;

[0191] (2) Add sodium silicate and a cross-linking agent to the above suspension, raise the temperature to 70°C, continue ultrasonication for 1 hour, filter, and dry at 80°C to obtain a functional filler; wherein the mass ratio of the suspension, sodium silicate and the cross-linking agent is 50:1:0.5, and the cross-linking agent is L-lysine.

[0192] Among them, the activator is zinc oxide and octadecyl acrylate in a mass ratio of 8:0.3, the plasticizer is polyethylene glycol-4000, the antioxidant is a mixture of antioxidant MB and antioxidant RD in a mass ratio of 0.5:0.7, the softener is paraffin oil 6030, the vulcanizer is di-tert-butyl peroxide diisopropylbenzene, and the co-crosslinking agent is triallyl isocyanurate.

[0193] A method for preparing a high temperature resistant and corrosion resistant food grade gasket material, comprising the following preparation steps:

[0194] S1. Add EPDM rubber blend into a closed rubber mixer, control the temperature of the closed rubber mixer to 85°C, the plasticizing speed to 40 rpm, the plasticizing time to 30 s, and mix well to obtain raw rubber;

[0195] S2, adding an activator, a plasticizer, an antioxidant, and a softener to the S1 raw rubber for a first mixing to obtain a first mixing product, adding a functional filler to the first mixing product, and uniformly mixing to obtain a second mixing product; controlling the mixing temperature of the first mixing product to be 130° C., the mixing speed to be 50 rpm, and the mixing time to be 120 s; controlling the mixing temperature of the second mixing product to be 140° C., the mixing speed to be 70 rpm, and the mixing time to be 180 s;

[0196] S3, in an open rubber mixer, mixing the second mixed product obtained in S2 with a vulcanizing agent and a cross-linking agent to prepare a final rubber compound; controlling the mixing temperature to be 150° C., the mixing speed to be 60 rpm, and the mixing time to be 120 s;

[0197] S4. The rubber compound in S3 is heated and pressurized for vulcanization at a vulcanization temperature of 150° C., a vulcanization time of 10 min, and a vulcanization pressure of 15 MPa. The mixture is cooled and shaped to obtain a high temperature resistant and corrosion resistant food grade gasket material.

[0198] Performance Testing

[0199] The comprehensive properties of the high temperature and corrosion resistant food grade gasket materials prepared in Examples 1-3 and Comparative Examples 1-10 of the present application were tested respectively, as follows:

[0200] Tensile strength test: Tested in accordance with national standard GB / T 528-2009;

[0201] Shore hardness test: Tested in accordance with GB / T 39693.7-2022;

[0202] Hot air accelerated aging test: Tested in accordance with national standard GB / T 3512-2014 (175℃×168h), followed by aging tensile strength test and Shore hardness performance comparison;

[0203] Oil corrosion resistance test: The prepared food-grade gasket material was immersed in FAM-B test solution (100℃×48h) for oil test, and then the corrosion tensile strength test and Shore hardness performance comparison were carried out;

[0204] The test results are shown in Table 1 below.

[0205] Table 1 Performance parameters of high temperature and corrosion resistant food grade gasket materials

[0206]

[0207] It can be seen from the data shown in Table 1 above that the high temperature and corrosion resistant food-grade gasket materials prepared in Examples 1-3 show excellent comprehensive performance in terms of thermal stability, mechanical strength, wear resistance, oil corrosion resistance, etc., and meet various application requirements.

[0208] It can be seen from Example 1 and Comparative Examples 1-4 that: in Example 1, a prefabricated EPDM rubber blend is used to improve the physical and mechanical properties of the composite material, such as tensile strength, hardness, and wear resistance. In Comparative Example 1, no low-density polyethylene is added. In Comparative Example 2, the low-density polyethylene is replaced with high-density polyethylene. Comparative Examples 3-4 respectively use only one type of EPDM rubber and low-density polyethylene for blending. The final product has different degrees of reduction in thermal stability, oil corrosion resistance, wear resistance, and hardness compared with Example 1.

[0209] It can be seen from Example 1 and Comparative Example 5 that in Example 1, a variety of carbon blacks with different structures are added as fillers, so that the material has the advantages of large specific surface area and high structure, and the tensile strength, wear resistance and oil corrosion resistance of EPDM products are significantly improved. In Comparative Example 5, only a single carbon black is added, and the comprehensive performance is significantly reduced.

[0210] It can be seen from Example 1 and Comparative Example 6 that in Example 1, carbon black and barium sulfate are used together as the functional filler base material, and in Comparative Example 6, barium sulfate and other materials are replaced with carbon black, and the comprehensive performance is significantly reduced.

[0211] It can be seen from Example 1 and Comparative Example 7 that the three-dimensional network structure formed by the combined action of sodium silicate and the cross-linking agent in Example 1 can further enhance the mechanical properties and stability of the functional filler, while in Comparative Example 7, only the cross-linking agent is used for surface modification, thereby affecting the thermal stability, corrosion resistance, wear resistance and other properties of the product.

[0212] It can be seen from Example 1 and Comparative Example 8 that: in Example 1, the filler base carbon black and barium sulfate were pretreated with a silane coupling agent, while in Comparative Example 8, the silane coupling agent was not used for pretreatment, and the comprehensive performance of the final product was significantly reduced.

[0213] It can be seen from Example 1 and Comparative Examples 9-10 that the combined use of 1,6-hexanediamine and L-lysine as a common cross-linking agent in Example 1 can form a more stable and functionally rich cross-linked network, promote interface bonding, improve mechanical strength, thermal stability and dispersibility, and exhibit excellent comprehensive performance to meet a variety of application requirements. In Comparative Examples 9-10, a single cross-linking agent is used, the cross-linking effect is poor, and the comprehensive performance is significantly reduced.

[0214] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A high temperature and corrosion resistant food grade gasket material, characterized in that: The invention comprises the following raw materials in parts by weight: 90-110 parts of EPDM rubber blend, 70-90 parts of functional filler, 4-6 parts of activator, 1-3 parts of plasticizer, 1-3 parts of antioxidant, 2-3 parts of softener, 3-5 parts of vulcanizer and 0.5-2 parts of cross-linking agent; the EPDM rubber blend is obtained by mixing EPDM rubber A, EPDM rubber B and polyethylene; the mass ratio of EPDM rubber A, EPDM rubber B and polyethylene is 1:1-1.5:0.2-0.3 , wherein the Mooney viscosity of EPDM rubber A is 20-30MU, the Mooney viscosity of EPDM rubber B is 70-90MU, the polyethylene is low-density polyethylene, and the melt flow rate of the low-density polyethylene is 4-8g / 10min; the activator is zinc oxide and octadecyl acrylate in a mass ratio of 8-12:0.3-0.8; the antioxidant is a mixture of antioxidant MB and antioxidant RD in a mass ratio of 0.5-1.5:0.7-1; the functional filler is prepared by the following method: (1) Add carbon black and barium sulfate to water at a temperature of 50-70°C, stir and mix, then add silane coupling agent, and ultrasonically disperse for 1-2 hours to obtain a suspension; (2) Add sodium silicate and a cross-linking agent to the above suspension, raise the temperature to 60-80°C, continue ultrasonication for 1-2 hours, filter, and dry to obtain a functional filler; The cross-linking agent is 1.6-hexanediamine and L-lysine in a mass ratio of 4-5:1-2.

2. The high temperature and corrosion resistant food grade gasket material according to claim 1, characterized in that: The invention comprises the following raw materials in parts by weight: 100 parts of EPDM rubber blend, 80 parts of functional filler, 5 parts of activator, 2 parts of plasticizer, 2 parts of antioxidant, 2.5 parts of softener, 4 parts of vulcanizer and 1.2 parts of cross-linking aid.

3. The high temperature and corrosion resistant food grade gasket material according to claim 1, characterized in that: The carbon black is a mixture of N550, N660 and N990 in a mass ratio of 45-55:15-25:5-15.

4. A method for preparing the high temperature and corrosion resistant food grade gasket material according to any one of claims 1 to 3, characterized in that: The method comprises the following preparation steps: S1. Add EPDM rubber blend into a closed rubber mixer, plasticize, and mix evenly to obtain raw rubber; S2, adding an activator, a plasticizer, an antioxidant, and a softener to the raw rubber of S1 for a first mixing to obtain a first mixing product, adding a functional filler to the first mixing product, and uniformly mixing to obtain a second mixing product; S3, in an open rubber mixer, mixing the second mixed product obtained in S2 with a vulcanizing agent and a co-crosslinking agent to prepare a final rubber mix; S4, the rubber compound in S3 is heated and pressurized in a vulcanizer for vulcanization, cooling, and shaping to obtain a high temperature resistant and corrosion resistant food grade gasket material.

5. The method for preparing the high temperature and corrosion resistant food grade gasket material according to claim 4, characterized in that: The mixing temperature of the first mixed product in S2 is 130-150° C., the mixing speed is 50-60 rpm, and the mixing time is 120-180 s; the mixing temperature of the second mixed product is 140-160° C., the mixing speed is 70-80 rpm, and the mixing time is 180-300 s.

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