A poly-ester derivative vulcanized epdm rubber material and a method for producing the same

Abstract

This invention discloses a polypolyester derivative vulcanized EPDM rubber material and its preparation method, aiming to solve the problems of oxygen inhibition, insufficient vulcanization of the outer surface, and point-like bubble defects, as well as increased oxygen removal costs, that occur in existing peroxide-vulcanized EPDM under bare vulcanization in a vulcanizing tank without oxygen removal, as well as the resulting increased oxygen removal costs. This material uses one of two alternative formulations by weight, including EPDM rubber, carbon black, silica powder, paraffin oil, activator, antioxidant, dispersing and tackifying resin, polyethylene wax, and a polypolyester derivative vulcanizing agent; the vulcanizing agent has a repeating unit structure of formula (I), where n is 3-6, the number average molecular weight is 400-1000, and it is a powdered solid. The preparation method employs a two-stage mixing process: in stage A, the mixture is discharged at approximately 130°C and left to stand; in stage B, the vulcanizing agent is added at no higher than 100°C, the mixture is extruded, and vulcanized at 170°C. This invention results in a smoother appearance, reduced risk of surface bubble defects, and better processing stability under bare vulcanization conditions without oxygen removal.

Description

Technical Field

[0001] This invention relates to the field of rubber materials technology, specifically to a polypolyester derivative vulcanized EPDM rubber material and its preparation method. Background Technology

[0002] With increasingly compact engine compartment spaces and stricter thermal management requirements, rubber components used in vehicle cooling systems undergo long-term service under high temperatures, high pressures, and coolant conditions. This places higher demands on the heat resistance, aging resistance, media resistance, and stability during extrusion and vulcanization molding of rubber materials. EPDM rubber, with its heat resistance, ozone resistance, and aging resistance, is commonly used in related rubber products.

[0003] In the existing technology, peroxide-cured EPDM rubber compounds have good heat resistance due to the formation of a cross-linked structure mainly composed of C and C bonds. However, under the condition of bare vulcanization in a vulcanizing tank without oxygen removal, the outer surface of the product is prone to insufficient vulcanization and appearance defects such as dot-like bubbles. Usually, it is necessary to add oxygen removal and other process steps to reduce the risk of defects, thereby increasing manufacturing costs and process complexity.

[0004] Therefore, there is an urgent need for a polypolyester derivative vulcanized EPDM rubber material that can reduce the risk of outer surface defects in oxygen-containing environments while also ensuring processing stability. Summary of the Invention

[0005] The technical problem to be solved by this invention is that existing peroxide-cured EPDM rubber compounds are prone to defects such as insufficient curing and pinpoint bubbles on the outer surface under bare vulcanization in a vulcanizing tank without oxygen removal, and usually require oxygen removal through vulcanization steam to improve the appearance, which leads to increased manufacturing costs. This invention provides a polypolyester derivative vulcanized EPDM rubber material and its preparation method, which can reduce the risk of appearance defects in bare vulcanization and improve processing stability while maintaining good heat resistance of the material.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: This polypolyester derivative vulcanized EPDM rubber material, by weight, comprises EPDM rubber, reinforcing agent, reinforcing filler, plasticizer, activator, dispersing and tackifying resin, processing aid, antioxidant, and polypolyester derivative vulcanizing agent, wherein the raw material composition and proportions adopt Scheme a or Scheme b; wherein... Scheme a comprises: 70 parts EPDM756, 30 parts EPDM512E, 45 parts carbon black N550, 20 parts carbon black N774, 45 parts silica powder A750, 50 parts paraffin oil 2261, 3.5 parts zinc oxide, 1.5 parts active magnesium oxide, 1 part stearic acid, 3 parts dispersing and tackifying resin LP1080, 1.5 parts polyethylene wax, 1.5 parts antioxidant RD, 1.5 parts antioxidant MB, and 8 parts polypolyester derivative vulcanizing agent; Scheme b includes: 100 parts EPDM756, 40 parts carbon black N550, 20 parts carbon black N774, 35 parts silica powder A750, 25 parts paraffin oil 2261, 3.5 parts zinc oxide, 1.5 parts active magnesium oxide, 1 part stearic acid, 3 parts dispersing and tackifying resin LP1080, 1.5 parts polyethylene wax, 1.5 parts antioxidant RD, 1.5 parts antioxidant MB, and 8 parts polypolyester derivative vulcanizing agent.

[0007] Furthermore, the polypolyester derivative vulcanizing agent has a repeating unit structure as shown in formula (I), where n is an integer from 3 to 6; the number average molecular weight of the polypolyester derivative vulcanizing agent is 400-1000, and it is a powdered solid.

[0008] Furthermore, the iodine uptake value of the active magnesium oxide is 150 mg / g.

[0009] Furthermore, the flash point of the paraffin oil 2261 is not lower than 248°C.

[0010] Furthermore, the antioxidant RD and the antioxidant MB are compounded in equal parts by weight.

[0011] The preparation method of this polypolyester derivative vulcanized EPDM rubber material includes the following steps: weighing raw materials according to Scheme a or Scheme b; adding EPDM rubber, activator, antioxidant, dispersing and tackifying resin and processing aid into an internal mixer and mixing for 1 min, then adding reinforcing agent, reinforcing filler and plasticizer and continuing to mix for 6 min, discharging at about 130°C, cooling and standing for 16-36 h to obtain compound A; adding compound A into an internal mixer, adding the polypolyester derivative vulcanizing agent, mixing at no higher than 100°C for 1.5 min and discharging, turning the rubber for about 3 min, sheeting and cooling and standing for 24 h to obtain compound; extruding the compound into a molding shape and vulcanizing at 170°C.

[0012] Furthermore, the vulcanization step is carried out without vacuuming and / or without replacement treatment with inert gas, vulcanizing vapor, etc. before vulcanization.

[0013] Bendo polyester derivative vulcanized EPDM rubber material is used in the manufacture of high-temperature and high-pressure water pipe materials for commercial vehicles.

[0014] This invention discloses a polypolyester derivative vulcanized EPDM rubber material. By employing a specific polypolyester derivative vulcanizing agent in the EPDM formulation and combining it with a two-stage mixing process, the rubber compound exhibits good processing stability. Furthermore, under bare vulcanization conditions in a vulcanizing tank without oxygen removal, it helps improve appearance consistency and reduce the risk of defects such as pinpoint bubbles. Simultaneously, the material of this invention meets the requirements for high-temperature applications, thus balancing appearance quality and heat resistance. Specifically: (1) Simplified process: Vacuuming and oxygen removal and / or replacement treatment of inert gas, sulfurization vapor, etc. are not required before vulcanization, reducing process steps and manufacturing costs; (2) Improved appearance: Compared with the control sample of the peroxide vulcanization system, the sample of the present invention has a smoother appearance under bare vulcanization and no oxygen release conditions, and the surface defects such as dotted bubbles are significantly reduced. (3) Heat resistance: The material of the present invention maintains good heat resistance and can be used in high-temperature conditions, avoiding the situation where heat resistance is significantly sacrificed by improving appearance; (4) Stable processing: Two-stage mixing and control of rubber temperature in the B-stage mixing stage helps to reduce the risk of pre-vulcanization and improve the stability of mixing, extrusion and vulcanization processes; (5) Performance meets: The relevant formulations of this invention meet the requirements for use in terms of hardness, tensile strength, elongation, tear strength, low temperature rebound and high temperature compression set. Attached Figure Description

[0015] The following description, in conjunction with the accompanying drawings, further illustrates the present invention: a polypolyester derivative vulcanized EPDM rubber material. Figure 1 The structural formula of the repeating unit structure described in Examples 1 and 2 is Formula (I); Figure 2 Photograph of the hose appearance of Comparative Example 3 (peroxide vulcanization system; internal formula number GY7535-1) under bare vulcanization in a vulcanizing tank without oxygen removal; Figure 3 This is a photograph of the appearance of the hose of the present invention under bare vulcanization conditions in a vulcanizing tank without oxygen removal. Detailed Implementation

[0016] To enable those skilled in the art to better understand the present invention, the following embodiments are provided for further illustration. It should be noted that the embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. Conditions not specified herein may be applied using conventional conditions in the art.

[0017] Example 1: By weight: 70 parts EPDM756, 30 parts EPDM512E, 45 parts carbon black N550, 20 parts carbon black N774, 45 parts silica powder A750, 50 parts paraffin oil 2261, 3.5 parts zinc oxide, 1.5 parts activated magnesium oxide (iodine absorption value 150), 1 part stearic acid, 3 parts dispersing and tackifying resin LP1080, 1.5 parts polyethylene wax, 1.5 parts antioxidant RD, 1.5 parts antioxidant MB, and 8 parts polypolyester derivative vulcanizing agent. The polypolyester derivative vulcanizing agent has the following properties: Figure 1 The repeating unit structure shown in formula (I) is used; where n is an integer from 3 to 6; its number-average molecular weight is 400-1000, and it is a powdered solid. The polyester derivative vulcanizing agent can be a product of model TDB680-a.

[0018] Example 2: By weight: 100 parts EPDM756, 40 parts carbon black N550, 20 parts carbon black N774, 35 parts silica powder A750, 25 parts paraffin oil 2261, 3.5 parts zinc oxide, 1.5 parts activated magnesium oxide (iodine absorption value 150), 1 part stearic acid, 3 parts dispersing and tackifying resin LP1080, 1.5 parts polyethylene wax, 1.5 parts antioxidant RD, 1.5 parts antioxidant MB, and 8 parts polypolyester derivative vulcanizing agent. The polypolyester derivative vulcanizing agent has the following properties: Figure 1 The repeating unit structure shown in formula (I) is used; where n is an integer from 3 to 6; its number-average molecular weight is 400-1000, and it is a powdered solid. The polyester derivative vulcanizing agent can be a product of model TDB680-a.

[0019] Example 3: This example provides a method for preparing a polyester derivative vulcanized EPDM rubber material, including the following steps: A-stage compound—After weighing the raw materials according to the formulation of Example 1 or Example 2, add EPDM rubber, activator, antioxidant, dispersing and tackifying resin LP1080, and processing aid polyethylene wax to a mixer and mix for 1 minute. Then add reinforcing agent carbon black, reinforcing filler silica powder A750, and plasticizer paraffin oil 2261 to the mixer and continue mixing for 6 minutes. The discharge temperature of the mixer is about 130°C. After the material is discharged from the clump, it is sheeted and cooled on a two-roll mill to obtain A-stage compound. A-stage compound is left to stand for 16-36 hours. B-stage mixing: The A-stage rubber is fed into an internal mixer, and a polypolyester derivative vulcanizing agent is added and mixed for 1.5 minutes, with the mixing temperature controlled not to exceed 100℃; after the material is discharged from the agglomeration, it is turned over in an open mill for about 3 minutes and then sheeted and cooled to obtain the compounded rubber; the compounded rubber is left to stand for 24 hours before use.

[0020] Extrusion and vulcanization – The compounded rubber can be extruded and vulcanized. During extrusion, a temperature range of 80°C at the die head, 70°C at the die body, 60°C at the feed section, and 50°C at the screw can be used, with an extrusion speed of 4-6 m / min. During vulcanization, flat vulcanization at 170°C for 15 min can be used to prepare test pieces for performance testing, or bare vulcanization in a vulcanizing tank at 170°C for 20 min can be used to vulcanize and mold rubber hose products. Two-stage vulcanization usually refers to vulcanization in a pressureless high-temperature chamber at approximately 150°C for 4-8 hours. The present invention can use one-stage vulcanization molding, eliminating the need for two-stage vulcanization.

[0021] Under the vulcanizing conditions in the vulcanizing tank, vacuuming and oxygen removal and / or replacement treatment with inert gas, vulcanizing vapor, etc., are not required before vulcanization.

[0022] To further verify the applicability of the polypolyester derivative vulcanization system of the present invention under different reinforcing systems and cost configurations, Examples 4, 5, and 6, as well as Comparative Examples 1 and 2, were established. Examples 4 to 6 all used polypolyester derivative vulcanizing agents as the vulcanization system; Comparative Example 1 used a peroxide vulcanization system; and Comparative Example 2 used a sulfur vulcanization system. The formulation components and proportions are shown in Table 1 below:

[0023] Example 4: The formulation of this example is shown in the column of Example 4 in Table 1. Its vulcanization system uses a polypolyester derivative vulcanizing agent (such as TDB680-a); its preparation method is the same as the two-stage mixing process described in Example 3.

[0024] Example 5: The formulation of this example is shown in the column of Example 5 in Table 1. Its vulcanization system uses a polypolyester derivative vulcanizing agent (such as TDB680-a); its preparation method is the same as the two-stage mixing process described in Example 3.

[0025] Example 6: The formulation of this example is shown in the column of Example 6 in Table 1. Its vulcanization system uses a polypolyester derivative vulcanizing agent (such as TDB680-a); its preparation method is the same as the two-stage mixing process described in Example 3.

[0026] Comparative Example 1: The formulation of this comparative example is shown in the column of Comparative Example 1 in Table 1. Its vulcanization system is a peroxide vulcanization system; its preparation method is carried out in accordance with the mixing and vulcanization process described in Example 3.

[0027] Comparative Example 2: The formulation of this comparative example is shown in the column of Comparative Example 2 in Table 1. Its vulcanization system is a sulfur vulcanization system; its preparation method is carried out in accordance with the mixing and vulcanization process described in Example 3.

[0028] The physical property test results of the products obtained from each formula are shown in Table 2 below:

[0029] As shown in Table 2, Examples 4 to 6, which use polypolyester derivative vulcanization systems, meet the requirements in terms of hardness, tensile strength, elongation, tear strength, low-temperature rebound, and high-temperature compression set. Comparative Example 2, which uses sulfur vulcanization system, is significantly inferior to the requirements in terms of compression set at 125℃ for 72 hours and shows failure after high-temperature aging.

[0030] MDR vulcanization characteristic test: The vulcanization characteristics of the samples of this invention were tested using a rotorless rheometer (MDR). The test conditions were 170℃ × 10 min. Parameters such as ML, MH, MH-ML, TS1, TS2, TS5, TC10, TC60, and TC90 were recorded to characterize the vulcanization rate window and crosslinking degree trend of the rubber compound. Several typical sets of data from the test records are shown in Table 3.

[0031] The above data is derived from readable records of MDR test screenshots; records without TS5 values ​​are indicated by "—". Different records correspond to different batches, formulations, or operating conditions, therefore the parameters may fluctuate to some extent, which is a normal phenomenon under formulation and process adjustments.

[0032] Comparative Example 3: This comparative example uses a control formulation (internal formulation number GY7535-1) for EPDM hoses with a peroxide vulcanization system, comprising, by weight: 60 parts EPDM rubber (Dow 4640), 40 parts EPDM rubber (Mitsui 4045), 5 parts zinc oxide, 1 part stearic acid, 3 parts wax, 1.5 parts antioxidant MB, 40 parts carbon black N550, 45 parts spray filler (subject to the applicant's actual use), 3.5 parts polyethylene glycol PEG4000, 3.5 parts odorless DCP, 1.5 parts HVA-2, 0.6 parts TAIC, and 1 part TBZTD. The remaining mixing and vulcanization methods are implemented according to conventional hose manufacturing processes.

[0033]

[0034] Comparison of bare vulcanized appearance: Rubber tube samples were prepared from the samples of this invention (e.g., the compound of Example 1) and the compound of Comparative Example 3, respectively. These samples were then subjected to bare vulcanization in a vulcanizing tank at 170°C without oxygen removal. The appearance after vulcanization is compared below. Figure 2 and Figure 3 As shown: Comparative Example 3 sample surface shows more dot-like bubbles; the sample surface of the present invention is smoother and the dot-like bubbles are significantly reduced, thus indicating that the present invention solution is beneficial to reducing the risk of outer surface defects under bare vulcanization and oxygen-free conditions.

[0035] To facilitate a consistent evaluation of the appearance of the bare vulcanized tubing, this embodiment employs the following appearance judgment method: After vulcanization, the outer surface of the tubing is visually observed, and representative areas are observed under a 10x stereomicroscope. If the outer surface is generally smooth, without any visible dot-like protruding bubbles, and no obvious bubble aggregation areas are observed under the microscope, it is judged as "appearance qualified"; otherwise, it is judged as "having bubbling defects". The above judgment method is used to illustrate the effects of the present invention and does not constitute a limitation on the scope of protection of the claims.

[0036] Preparation: B-component rubber is fed into an extruder and plasticized and extruded within a temperature range of 80°C at the die head, 70°C in the die body, 60°C in the feeding section, and 50°C at the screw. The extrusion speed is controlled at 4-6 m / min to obtain stable dimensions and surface quality. The extruded rubber tube is then vulcanized in a vulcanizing tank at 170°C. During vulcanization, the polypolyester derivative vulcanizing agent is activated by heat and participates in the crosslinking reaction, forming a crosslinking network with the EPDM molecular chains. Through this vulcanization system combined with the two-stage mixing process, the vulcanization process of the rubber compound in an oxygen-containing environment is more stable. This improves appearance consistency and reduces the risk of defects such as pinhole bubbles under the condition of bare vulcanization in the vulcanizing tank without oxygen release.

[0037] The foregoing description illustrates the main features, basic principles, and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments or examples described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the above embodiments or examples should be considered exemplary and not restrictive. The scope of the present invention is defined by the appended claims rather than the foregoing description, and therefore all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0038] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A polypolyester derivative vulcanized EPDM rubber material, characterized in that: The material preparation formula, by weight parts, is either scheme a or scheme b; wherein... Scheme a comprises: 70 parts EPDM756, 30 parts EPDM512E, 45 parts carbon black N550, 20 parts carbon black N774, 45 parts silica powder A750, 50 parts paraffin oil 2261, 3.5 parts zinc oxide, 1.5 parts active magnesium oxide, 1 part stearic acid, 3 parts dispersing and tackifying resin LP1080, 1.5 parts polyethylene wax, 1.5 parts antioxidant RD, 1.5 parts antioxidant MB, and 8 parts polypolyester derivative vulcanizing agent; Scheme b includes: 100 parts EPDM756, 40 parts carbon black N550, 20 parts carbon black N774, 35 parts silica powder A750, 25 parts paraffin oil 2261, 3.5 parts zinc oxide, 1.5 parts active magnesium oxide, 1 part stearic acid, 3 parts dispersing and tackifying resin LP1080, 1.5 parts polyethylene wax, 1.5 parts antioxidant RD, 1.5 parts antioxidant MB, and 8 parts polypolyester derivative vulcanizing agent.

2. The polypolyester derivative vulcanized EPDM rubber material according to claim 1, characterized in that: The polypolyester derivative vulcanizing agent has a repeating unit structure as shown in formula (I), where n is an integer from 3 to 6; the number average molecular weight of the polypolyester derivative vulcanizing agent is 400-1000, and it is a powder solid.

3. The polypolyester derivative vulcanized EPDM rubber material according to claim 1, characterized in that: The iodine uptake value of the active magnesium oxide is 150 mg / g.

4. The polypolyester derivative vulcanized EPDM rubber material according to claim 1, characterized in that: The flash point of the paraffin oil 2261 is not lower than 248°C.

5. The polyester derivative vulcanized EPDM rubber material according to claim 1, characterized in that: The antioxidant RD and the antioxidant MB are compounded in equal parts by weight.

6. A method for preparing a polypolyester derivative vulcanized EPDM rubber material, characterized in that: The polypolyester derivative vulcanized EPDM rubber material is the polypolyester derivative vulcanized EPDM rubber material according to any one of claims 1 to 5, and the preparation method includes the following steps: A-component: Add EPDM rubber, activator, antioxidant, dispersing and tackifying resin and processing aid to a mixer and mix for 1 minute. Then add reinforcing agent, reinforcing filler and plasticizer and continue mixing for 6 minutes. Discharge the material at about 130°C, cool and let it stand for 16-36 hours to obtain A-component rubber. B-stage mixing: The A-stage rubber is fed into an internal mixer, the polypolyester derivative vulcanizing agent is added, and the mixture is mixed at a temperature not exceeding 100°C for 1.5 minutes before discharge. The rubber is then turned over for about 3 minutes, and after being sheeted and cooled, it is left to stand for 24 hours to obtain the compounded rubber. Vulcanization: The compound is extruded and vulcanized at 170°C.

7. The method for preparing polyester derivative vulcanized EPDM rubber material according to claim 6, characterized in that: The vulcanization step is carried out without vacuuming and / or without inert gas or vulcanization vapor replacement treatment before vulcanization.

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