Mixing process of ethylene propylene diene monomer
By employing a step-by-step kneading, open mill turning, and precise temperature control process for EPDM rubber compounding, the problems of uneven dispersion of additives and premature reaction of vulcanizing agents have been solved, thereby improving the physical and mechanical properties and production stability of the rubber compound.
Patent Information
- Application Number
- CN202511985530.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-26
- Publication Date
- 2026-02-24
AI Technical Summary
The existing EPDM rubber compounding process has problems such as high risk of impurities and cross-contamination, uneven dispersion of additives, risk of premature reaction of vulcanizing agents, and poor process standardization, which lead to a decrease in rubber purity and poor physical and mechanical properties.
The process employs step-by-step kneading and open mill turning operations, combined with precise time and temperature control, clean production lines, and filter screens to ensure uniform dispersion of additives. Furthermore, the post-addition of vulcanizing agents prevents premature reactions, and clear storage and filter screen replacement cycles are established.
It significantly reduces the agglomeration rate of additives, increases the tensile strength of rubber compounds by 10% to 15%, reduces impurity content by 90%, controls the performance fluctuation of rubber compounds within ±5%, and improves production stability and finished product quality.
Smart Images
Figure CN121552546A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of rubber preparation technology, and specifically to a mixing process for EPDM rubber. Background Technology
[0002] Ethylene propylene diene monomer (EPDM) rubber is an elastomer copolymerized from ethylene, propylene, and non-conjugated diene monomers. It has excellent resistance to ozone aging, weathering, and chemical corrosion. With the addition of various additives, it forms a compound that is widely used in the automotive, construction, electronics, and petrochemical industries.
[0003] The materials in an existing EPDM rubber compounding process are as follows: Main rubber: 100 parts EPDM rubber; Additives: 2 parts antioxidant RD, 2 parts antioxidant 1010, 5 parts zinc oxide, 5 parts semi-reinforcing carbon black, 2 parts silane coupling agent A172, 5 parts silica, 5 parts polybutadiene, 10 parts paraffin oil, 20 parts calcined clay, 10 parts talc, and 4 parts DCP.
[0004] However, the mixing process of EPDM rubber has stringent requirements for process conditions, and existing processes generally have the following problems: ① High risk of impurities and cross-contamination: Incomplete cleaning of mixing equipment (such as kneaders and open mills), auxiliary devices (such as pallets and conveyor belts) and production environment (ground, weighing tools) can easily leave behind previous rubber materials or external impurities, leading to a decrease in the purity of the final rubber material and affecting the performance of the product. ② Uneven dispersion of additives: Ethylene propylene diene monomer (EPDM) rubber has a high viscosity. If the order of addition of additives (such as antioxidants, fillers, coupling agents), the mixing time, or the temperature control are not appropriate, additives are prone to agglomeration, which will lead to low physical and mechanical properties of the rubber compound (such as tensile strength and tear strength). ③ Risk of premature reaction of vulcanizing agent: If the vulcanizing agent (such as dicumyl peroxide, DCP) is mixed with other additives at the same time or the mixing temperature is too high, premature vulcanization (scorching) is likely to occur, causing the rubber compound to lose its processing fluidity and become unable to be molded in the subsequent process. ④ Poor process standardization: The selection and replacement cycle of filters in the glue filtration process are unclear, and the storage time and environment of the glue are not strictly limited, resulting in large fluctuations in the quality of different batches of glue and insufficient production stability. Summary of the Invention
[0005] In view of this, the purpose of the present invention is to provide a mixing process for EPDM rubber to solve the technical problems of uneven dispersion of additives and low physical and mechanical properties of rubber compounds in the existing EPDM rubber mixing process.
[0006] This invention is achieved through the following technical solution: A compounding process for EPDM rubber includes the following steps: S1. Prepare materials; S2. Kneading and plasticizing: Put the EPDM rubber block into the kneader and plasticize for 1 to 1.5 minutes. Control the plasticizing temperature to ≤90℃. When the temperature drops to 65℃, start pressing to ensure that the rubber block is broken up evenly. S3. Initial mixing of additives in the kneader: Add antioxidant RD, antioxidant 1010, zinc oxide, semi-reinforcing carbon black, and white carbon black. When lowering the top bolt, slowly apply pressure and mix for 2 to 2.5 minutes until the rubber compound and additives are evenly mixed and form blocks. S4. Kneading machine additive final mixing: Add calcined clay, talc powder, silane coupling agent A172, paraffin oil, and polybutadiene, and knead for 2 to 2.5 minutes until the rubber compound is fully uniform and forms clumps. S5. Open mill processing 1: Put the kneaded rubber compound into the open mill and mix for 3-4 minutes. Automatically turn the rubber compound 2-3 times to ensure that the rubber compound completely covers the rollers and control the thickness of the rubber sheet to be 4-5 mm. S6. Filtering with a rubber filter: The rubber compound processed by the open mill is sent to a rubber filter for filtration. S7. Processing on the open mill: The filtered rubber compound is fed back into the open mill, formed into 2-3 triangular bundles, and mixed for 2-3 minutes. The thickness of the rubber sheet is controlled to be 3-4 mm. After being rolled into rolls, it is conveyed to the next stage.
[0007] Furthermore, the materials prepared in step S1 are: Main rubber: 100 parts of EPDM rubber; Additives: 2 parts of antioxidant RD, 2 parts of antioxidant 1010, 5 parts of zinc oxide, 5 parts of semi-reinforcing carbon black, 2 parts of silane coupling agent A172, 5 parts of silica, 5 parts of polybutadiene, 10 parts of paraffin oil, 20 parts of calcined clay, 10 parts of talc, and 4 parts of DCP.
[0008] Furthermore, prior to step S2, the production line is cleaned to remove impurities and residual adhesive through thorough cleaning.
[0009] Furthermore, cleaning the production line includes cleaning the main equipment, auxiliary equipment, measuring tools, and the environment.
[0010] Furthermore, in step S6, a three-layer 60-mesh filter is used for filtration, and cooling water is continuously circulated during the filtration process; the first batch of rubber in the rubber filter machine must use hot rubber with a temperature ≥80℃, and the filter screen is replaced every 7 batches of rubber filtered.
[0011] Furthermore, it also includes step S8 following step S7: The rubber compound is calendered, cooled, powdered, and wound up. The compound is then stored for more than 24 hours and then vulcanized to obtain a rubber compound containing a vulcanizing agent.
[0012] Furthermore, in step S8, the vulcanization treatment of the rubber compound includes the following steps: S81. Kneading in a kneader: Add 1 / 2 of the base rubber compound to the kneader, add the vulcanizing agent DCP, and then add the remaining 1 / 2 of the base rubber compound. Knead for 1 to 1.5 minutes, controlling the kneading temperature to ≤90℃ to ensure that the DCP is evenly dispersed. S82. Open mill processing: Put the rubber compound containing vulcanizing agent into the open mill, mix for 3-4 minutes, and automatically turn the rubber 2-3 times to ensure that the rubber compound completely covers the rollers and control the thickness of the rubber sheet to 4-5 mm.
[0013] Furthermore, step S9 is included: calendering, cooling, powdering, and winding the vulcanizing agent-containing rubber compound, and then storing it for 24 hours under the following conditions: 25°C, in a dark environment, avoiding direct sunlight, and ensuring that the rubber compound does not come into direct contact with the ground. It must be covered with a dustproof bag during storage; and the vulcanizing agent-containing rubber sheet must be used within 30 days.
[0014] In the EPDM rubber compounding process described in this invention, through stepwise kneading of plasticizing, initial mixing, and final mixing, combined with precise time and temperature control, the order of addition of various additives, and the operation of turning the rubber on the open mill and forming triangular bundles, the additive agglomeration rate is reduced by ≥80%, and the tensile strength of the rubber compound is increased by 10% to 15%. The EPDM rubber compounding process described in this invention can improve the uniformity of additive dispersion and enhance the physical and mechanical properties of the rubber compound.
[0015] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description
[0016] Figure 1 This is a flowchart of the mixing process of EPDM rubber according to the present invention. Detailed Implementation
[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.
[0018] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.
[0019] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.
[0020] In the above description of the present invention, it should be noted that the terms "one side," "the other side," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the invention is conventionally placed during use. These terms are used only for the convenience of describing the present invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.
[0021] Furthermore, terms such as "identical" do not imply that components must be absolutely identical; minor differences are permissible. The term "perpendicular" simply means that the positional relationship between components is more perpendicular than "parallel," not that the structure must be perfectly perpendicular; a slight tilt is acceptable.
[0022] Please see Figure 1 This invention provides a technical solution: a compounding process for ethylene propylene diene monomer (EPDM) rubber, comprising the following steps: S1. Prepare materials; Specifically, the materials prepared in step S1 are: Main rubber: 100 parts of EPDM rubber; Additives: 2 parts of antioxidant RD, 2 parts of antioxidant 1010, 5 parts of zinc oxide, 5 parts of semi-reinforcing carbon black, 2 parts of silane coupling agent A172, 5 parts of silica, 5 parts of polybutadiene, 10 parts of paraffin oil, 20 parts of calcined clay, 10 parts of talc, and 4 parts of DCP.
[0023] Except for EPDM rubber, clay, and talc, all other additives are weighed using an electronic scale with a weighing accuracy of ≤±0.1kg. EPDM rubber is cut into blocks of ≤5kg / piece, preferably into blocks of 4kg / piece.
[0024] S2. Kneading and plasticizing: Put the EPDM rubber block into the kneader and plasticize for 1 to 1.5 minutes. Control the plasticizing temperature to ≤90℃. When the temperature drops to 65℃, start pressing to ensure that the rubber block is broken up evenly. Specifically, the kneading machine can be a model XSN-75 kneading machine, the amount of EPDM rubber block fed into the kneading machine is 100 parts, the plasticizing time is preferably 1.2 min, and the plasticizing temperature is preferably 85℃.
[0025] S3. Initial mixing of additives in the kneader: Add antioxidant RD, antioxidant 1010, zinc oxide, semi-reinforcing carbon black, and white carbon black. When lowering the top bolt, slowly apply pressure and mix for 2 to 2.5 minutes until the rubber compound and additives are evenly mixed and form blocks. Specifically, the added antioxidant RD is 2 parts, antioxidant 1010 is 2 parts, zinc oxide is 5 parts, semi-reinforcing carbon black is 5 parts, and white carbon black is 5 parts. The preferred mixing time is 2.3 minutes.
[0026] S4. Kneading machine additive final mixing: Add calcined clay, talc powder, silane coupling agent A172, paraffin oil, and polybutadiene, and knead for 2 to 2.5 minutes until the rubber compound is fully uniform and forms clumps. Specifically, the added calcined clay is 20 parts, talc is 10 parts, silane coupling agent A172 is 2 parts, paraffin oil is 10 parts, and polybutadiene is 5 parts, with a preferred mixing time of 2.4 min.
[0027] S5. Open mill processing 1: Put the kneaded rubber compound into the open mill and mix for 3-4 minutes. Automatically turn the rubber compound 2-3 times to ensure that the rubber compound completely covers the rollers and control the thickness of the rubber sheet to be 4-5 mm. Specifically, the open mill can be an XK-450 open mill, the mixing time is preferably 3.5 min, the number of times the rubber is turned is preferably 2, and the sheet thickness is preferably 4.5 mm; S6. Filtering with a rubber filter: The rubber compound processed by the open mill is sent to a rubber filter for filtration. Specifically, the rubber filter can be a model XJL-200 rubber filter, which uses a three-layer 60-mesh filter screen and continuously circulates cooling water during the filtration process; the first batch of rubber in the rubber filter needs to use hot rubber with a temperature ≥80℃, and the filter screen is replaced every 7 batches of rubber filtered.
[0028] The preferred temperature of the cooling water is 25°C, and after filtration, the rubber compound is free of visible impurities. The preferred temperature for the first batch of rubber in the rubber filter is 85°C.
[0029] Filtering rubber compounds through a rubber filter can reduce impurities and improve the quality of subsequent finished products.
[0030] S7. Processing on the open mill: The filtered rubber compound is fed back into the open mill, formed into 2-3 triangular bundles, and mixed for 2-3 minutes. The thickness of the rubber sheet is controlled to be 3-4 mm. After being rolled into rolls, it is conveyed to the next stage.
[0031] Specifically, the preferred number of triangular packets is 3, the preferred mixing time is 2.2 min, and the preferred film thickness is 3.5 mm; Through stepwise kneading of plasticizing, initial mixing, and final mixing, combined with precise time and temperature control, the order of addition of various additives, and the operation of turning and forming triangular bundles on the open mill, the agglomeration rate of additives is reduced by ≥80%, and the tensile strength of the rubber compound is increased by 10% to 15%. The EPDM rubber mixing process described in this invention can improve the uniformity of additive dispersion and improve the physical and mechanical properties of the rubber compound.
[0032] In this embodiment, before step S2, the production line is cleaned to remove impurities and residual adhesive through thorough cleaning.
[0033] Specifically: a. Cleaning of main equipment: Roll and clean the mixing chamber and rotor of the kneader twice with EPDM rubber sheets until there is no residue on the surface; clean the residual rubber on the rollers of the open mill with a copper wire brush, and then roll with EPDM rubber sheets once; clean the filter plates of the filter press and the rollers of the three-roll calender; if there is stubborn rubber residue on the surface of the equipment, it can be repeatedly rolled and cleaned with a small amount of EPDM rubber resin until there is no visible residue on the surface.
[0034] b. Cleaning of auxiliary equipment: Wipe or use high-pressure air to clean the equipment's trays, elevators, conveyor belts, and glue boxes to ensure no dead glue residue remains; wipe the material container with alcohol and let it dry.
[0035] c. Cleaning the measuring tools: Clean the electronic scale to ensure weighing accuracy.
[0036] d. Cleaning the environment: Sweep the production line floor twice with a vacuum cleaner to prevent dust and impurities from being brought into the mixing process with the rubber material or tools.
[0037] By cleaning the entire production line, impurities and residual rubber can be effectively removed, reducing cross-contamination. Combined with the filtration and removal of impurities from the rubber compound by a rubber filter, the impurity content of the rubber compound can be reduced by more than 90%.
[0038] In this embodiment, step S8, following step S7, is also included: The rubber compound is calendered, cooled, powdered, and wound up. The compound is then stored for more than 24 hours and then vulcanized to obtain a rubber compound containing a vulcanizing agent.
[0039] Calendering: The film roll is calendered into a film sheet with a thickness of 2-2.5 mm and a width of 490-510 mm using a three-roll calender; preferably, the thickness of the calendered film roll is 2.2 mm and the width is 500 mm.
[0040] Cooling: The film is cooled to room temperature by circulating cooling water through an eight-roller cooler; specifically, the cooling water temperature is 20°C and the film is cooled to 25°C.
[0041] Powder coating: The cooled film is uniformly coated with a separating powder using a powder coating machine; the separating powder is preferably talc powder.
[0042] Rewinding: The powder-coated film is evenly wound up using a rewinding machine and placed in a glue box for storage for 24 hours. The stored glue is the base glue, and preferably, the storage temperature is 25℃.
[0043] After adding and mixing other additives, the vulcanizing agent CPC is added to vulcanize the base rubber compound. This "vulcanizing agent added later" mode completely avoids the risk of premature vulcanization, prevents the rubber compound from losing its processing fluidity and thus being unable to be molded later, and improves vulcanization efficiency by 20% to 25%.
[0044] In this embodiment, step S8, the vulcanization treatment of the rubber compound includes the following steps: S81. Kneading in a kneader: Add 1 / 2 of the base rubber compound to the kneader, add the vulcanizing agent DCP, and then add the remaining 1 / 2 of the base rubber compound. Knead for 1 to 1.5 minutes, controlling the kneading temperature to ≤90℃ to ensure that the DCP is evenly dispersed. Specifically, the base compound consists of 100 parts, DCP consists of 4 parts, and 1 / 2 base compound consists of 50 parts. The preferred mixing time is 1.3 minutes, and the preferred temperature is 80℃.
[0045] S82. Open mill processing: Put the rubber compound containing vulcanizing agent into the open mill, mix for 3-4 minutes, and automatically turn the rubber 2-3 times to ensure that the rubber compound completely covers the rollers and control the thickness of the rubber sheet to 4-5 mm.
[0046] Specifically, the mixing time is preferably 3.2 min, the number of times the rubber is turned is preferably 3, and the thickness of the rubber sheet is preferably 4.2 mm.
[0047] In this embodiment, step S9 is also included: calendering, cooling, powdering and winding the rubber compound containing vulcanizing agent, and then storing it for 24 hours. The storage conditions are: 25°C, stored in a light-proof environment, avoiding direct sunlight, and the rubber compound is not allowed to directly contact the ground. It must be covered with a dustproof bag during storage; and the rubber sheet containing vulcanizing agent must be used up within 30 days.
[0048] Calendering: The rubber compound is calendered into a sheet with a thickness of 2-2.5 mm and a width of 245-255 mm using a three-roll calender. The preferred calendering thickness is 2.3 mm and the preferred width is 250 mm.
[0049] Cooling: The film is cooled to 25°C by circulating cooling water through an eight-roller cooler.
[0050] Powder coating: Apply isolation powder evenly using a powder coating machine; the isolation powder is preferably talc powder.
[0051] Rewinding: The powder-coated film is evenly wound up using a rewinding machine and stored for 24 hours. Storage conditions: 25℃, protected from direct sunlight, and the film must not come into direct contact with the ground. It must be covered with a dust bag during storage. Films containing vulcanizing agents must be used within 30 days.
[0052] Performance testing of finished rubber compounds: Impurity content: ≤0.05%, the detection method is to observe the finished adhesive under a microscope at 400x magnification; Tensile strength: 12.5 MPa, conforming to the requirements of GB / T 528-2009; Vulcanization rate (180℃): T90 = 4.5 min, with no scorching. Batch variation: tensile strength variation ±3.2%.
[0053] The EPDM rubber mixing process described in this invention specifies the rubber compound storage time, filter replacement cycle, and vulcanizing agent usage cycle, thereby controlling the performance fluctuation range of different batches of rubber compounds within ±5%.
[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.
Claims
1. A mixing process for EPDM rubber, characterized in that, Includes the following steps: S1. Prepare materials; S2. Kneading and plasticizing: Put the EPDM rubber block into the kneader and plasticize for 1 to 1.5 minutes. Control the plasticizing temperature to ≤90℃. When the temperature drops to 65℃, start pressing to ensure that the rubber block is broken up evenly. S3. Initial mixing of additives in the kneader: Add antioxidant RD, antioxidant 1010, zinc oxide, semi-reinforcing carbon black, and white carbon black. When lowering the top bolt, slowly apply pressure and mix for 2 to 2.5 minutes until the rubber compound and additives are evenly mixed and form blocks. S4. Kneading machine additive final mixing: Add calcined clay, talc powder, silane coupling agent A172, paraffin oil, and polybutadiene, and knead for 2 to 2.5 minutes until the rubber compound is fully uniform and forms clumps. S5. Open mill processing 1: Put the kneaded rubber compound into the open mill and mix for 3-4 minutes. Automatically turn the rubber compound 2-3 times to ensure that the rubber compound completely covers the rollers and control the thickness of the rubber sheet to be 4-5 mm. S6. Filtering with a rubber filter: The rubber compound processed by the open mill is sent to a rubber filter for filtration. S7. Processing on the open mill: The filtered rubber compound is fed back into the open mill, formed into 2-3 triangular bundles, and mixed for 2-3 minutes. The thickness of the rubber sheet is controlled to be 3-4 mm. After being rolled into rolls, it is conveyed to the next stage.
2. The mixing process for EPDM rubber according to claim 1, characterized in that, The materials prepared in step S1 are: Main rubber: 100 parts of EPDM rubber; Additives: 2 parts of antioxidant RD, 2 parts of antioxidant 1010, 5 parts of zinc oxide, 5 parts of semi-reinforcing carbon black, 2 parts of silane coupling agent A172, 5 parts of silica, 5 parts of polybutadiene, 10 parts of paraffin oil, 20 parts of calcined clay, 10 parts of talc, and 4 parts of DCP.
3. The mixing process for EPDM rubber according to claim 1, characterized in that: Before step S2, the production line is cleaned to remove impurities and residual adhesive through thorough cleaning.
4. The mixing process for EPDM rubber according to claim 1, characterized in that: Cleaning the production line includes cleaning the main equipment, auxiliary equipment, measuring tools, and the environment.
5. The mixing process for EPDM rubber according to claim 1, characterized in that: In step S6, a three-layer 60-mesh filter is used for filtration, and cooling water is continuously circulated during the filtration process; the first batch of rubber in the rubber filter machine must use hot rubber with a temperature ≥80℃, and the filter screen is replaced every 7 batches of rubber filtered.
6. The mixing process for EPDM rubber according to claim 1, characterized in that, It also includes step S8 following step S7: The rubber compound is calendered, cooled, powdered, and wound up. The compound is then stored for more than 24 hours and then vulcanized to obtain a rubber compound containing a vulcanizing agent.
7. The mixing process for EPDM rubber according to claim 6, characterized in that: In step S8, the vulcanization treatment of the rubber compound includes the following steps: S81. Kneading in a kneader: Add 1 / 2 of the base rubber compound to the kneader, add the vulcanizing agent DCP, and then add the remaining 1 / 2 of the base rubber compound. Knead for 1 to 1.5 minutes, controlling the kneading temperature to ≤90℃ to ensure that the DCP is evenly dispersed. S82. Open mill processing: Put the rubber compound containing vulcanizing agent into the open mill, mix for 3-4 minutes, and automatically turn the rubber 2-3 times to ensure that the rubber compound completely covers the rollers and control the thickness of the rubber sheet to 4-5 mm.
8. The mixing process for EPDM rubber according to claim 6, characterized in that... It also includes step S9: calendering, cooling, powdering and winding the rubber compound containing vulcanizing agent, and then storing it for 24 hours. The storage conditions are: 25℃, stored in a dark environment, avoiding direct sunlight, and the rubber compound is not allowed to directly contact the ground. It must be covered with a dust bag during storage; and the rubber sheet containing vulcanizing agent must be used within 30 days.