Green, environment-friendly, flame-retardant and low-odor automobile sealing strip rubber compound and preparation method thereof

Abstract

The green environment-friendly flame-retardant low-odor automobile sealing strip rubber compound is prepared from the following components in parts by mass: 100 parts of ethylene propylene rubber, 10 to 30 parts of carbon black, 30 to 50 parts of a halogen-free flame retardant, 5 parts of zinc oxide, 1 part of stearic acid, 30 parts of a softening plasticizer, 1 part of an anti-aging agent RD, 1 part of an anti-aging agent 4010NA, 1.5 parts of a vulcanizing agent and an accelerant combination. The accelerator composition comprises 1.2 parts of each component. The prepared material is good in flame retardance, high in thermal aging resistance, environmentally friendly and low in odor, the flame retardance of ethylene propylene rubber is greatly improved, and the requirement of customers for the flame retardance of automobile sealing strips can be met.

Description

Technical Field

[0001] The present invention relates to a green environmental protection flame-retardant and low-odor automotive sealing strip compound and a preparation method thereof, belonging to the field of rubber. Background Art

[0002] Since the molecular structure of ethylene-propylene rubber is mainly composed of C-C bonds, it lacks polarity, has a low degree of saturation, and has extremely high chemical stability and excellent aging resistance. Therefore, ethylene-propylene rubber is widely used in the automotive parts industry. However, some parts may accidentally come into contact with an open flame during maintenance and repair. Since ethylene-propylene rubber itself has a low flash point, that is, very low flame retardancy, it may cause damage such as combustion of automotive rubber sealing strips. Therefore, customers need an ethylene-propylene rubber compound with certain combustion resistance and at the same time environmental protection and low odor.

[0003] In the prior art, for example, the invention with the application number 202010012305.X discloses a flame-retardant and antistatic rubber double-density sole compound and a preparation method thereof. Calculated by weight, the foamed midsole includes 100 parts of nitrile rubber NBR6240, 25 parts of nitrile rubber NBR7030, 1 part of emulsifier, 20 parts of black paste, 15 parts of white carbon black, 15 parts of reinforcing agent N330, 5 parts of active zinc oxide, 15 parts of red phosphorus, 2 parts of antimony trioxide, 5 parts of chlorinated paraffin, 40 parts of dioctyl phthalate, 2 parts of accelerator, 5 parts of the first antistatic agent, 2 parts of vulcanizing agent, 2 parts of dicumyl peroxide, and 2 parts of rubber urea; the rubber outsole includes 100 parts of nitrile rubber KNB35LM, 45 parts of cis-butadiene rubber, 5 parts of active zinc oxide, 15 parts of red phosphorus, 5 parts of antimony trioxide, 5 parts of emulsifier, 2 parts of antioxidant 4010NA, 1 part of antioxidant RD, 45 parts of carbon black, 25 parts of white carbon black, 5 parts of chlorinated paraffin, 30 parts of dioctyl phthalate, 5 parts of the second antistatic agent, 5 parts of coupling agent, 5 parts of accelerator, 3 parts of vulcanizing agent, and 1 part of mold release agent. The sole compound has strong flame-retardant and antistatic properties.

[0004] However, in the above technology, when chlorinated paraffin is added as a flame retardant, harmful halogen-containing gases such as hydrogen chloride may be released during combustion. These gases not only pollute the environment but may also cause secondary hazards during a fire, causing serious harm to the human respiratory tract, etc., and do not meet the current trend of green environmental protection and the requirements of strict environmental protection regulations. At the same time, various chemical substances in the formula, such as plasticizers like dioctyl phthalate, may be difficult to degrade in the environment and will accumulate in environmental media such as soil and water over time, posing a potential threat to the balance of the ecosystem. At the same time, these substances may affect the recycling of the rubber sole after the end of the product's service life, increasing the treatment difficulty and environmental burden.

[0005] Therefore, it is necessary to propose a design of a green environmental protection flame-retardant and low-odor mixing rubber material for automotive sealing strips to meet the requirements of customers for the flame retardancy of automotive sealing strips while avoiding environmental pollution. Summary of the Invention

[0006] The present invention provides a green environmental protection flame-retardant and low-odor mixing rubber for automotive sealing strips and a preparation method thereof. The material has good flame retardancy, strong heat aging resistance, is green and environmentally friendly with low odor, greatly improves the flame retardancy of ethylene-propylene rubber, and can meet the requirements of customers for the flame retardancy of automotive sealing strips.

[0007] The technical solution adopted by the present invention to solve its technical problems is as follows:

[0008] A green environmental protection flame-retardant and low-odor mixing rubber for automotive sealing strips, by mass fraction, each component includes: ethylene-propylene rubber: 100 parts, carbon black N550: 10 - 30 parts, halogen-free flame retardant MM-X1: 30 - 50 parts, zinc oxide ZNOA: 5 parts, stearic acid SA: 1 part, softening plasticizer PIONIER1535: 30 parts, antioxidant RD: 1 part, antioxidant 4010NA: 1 part, vulcanizing agent S-80HE: 1.5 parts, and accelerator combination;

[0009] Among them, the accelerator combination is a mixture of ZDTP-50, ZDEC-70, ZBEC-70, CBS-80, and TMTD-75, and the mass fraction of each component in the accelerator combination is 1.2 parts;

[0010] Further, the grade of ethylene-propylene rubber selected is EPDM3092PM or Keltan2470C or EPDM5601;

[0011] The preparation method of the green environmental protection flame-retardant and low-odor mixing rubber for automotive sealing strips specifically includes the following steps:

[0012] Step S1, put ethylene-propylene rubber into a mixer for mixing until the ethylene-propylene rubber forms a uniform rubber matrix;

[0013] Step S2, put carbon black N550, halogen-free flame retardant MM-X1, zinc oxide ZNOA, stearic acid SA, softening plasticizer PIONIER1535, antioxidant RD, and antioxidant 4010NA into the rubber matrix for primary mixing with ethylene-propylene rubber;

[0014] Step S3, after the primary mixing is completed, discharge the mixed rubber from the mixer, evaluate its state, if it meets the set requirements, put the mixed rubber into an open mill, roll the mixed rubber and then take out the rubber sheet for standby;

[0015] Step S4, let the rubber sheet obtained after the primary mixing stand for a preset time;

[0016] Step S5: Recharge the film after parking into the internal mixer for secondary refining. After sufficient secondary mixing, discharge the film.

[0017] Step S6: Charge the film obtained after secondary mixing, sulfur agent S-80HE, accelerator ZDTP-50, accelerator ZDEC-70, accelerator ZBEC-70, accelerator CBS-80, and accelerator TMTD-75 into the internal mixer for the third mixing. After the third mixing is completed, discharge the mixed rubber compound from the internal mixer, and confirm the state of the mixed rubber compound to complete the mixing.

[0018] Furthermore, in step S1, set the rotation speed of the internal mixer to 40 r / min and the initial refining temperature to 35°C. After 60 - 90 seconds of continuous refining, the refining temperature reaches 100°C ± 10°C.

[0019] In step S2, during the initial mixing, continue to set the rotation speed of the internal mixer to 40 r / min. After 150 - 180 seconds of continuous mixing, the mixing temperature reaches 150 - 160°C.

[0020] In step S3, after the initial mixing is completed, use a thermometer to measure the temperature of the mixed rubber compound discharged from the internal mixer. If the temperature is between 140°C and 150°C, and there are no impurities on the surface of the film or the surface impurity particle size ≤ 3 mm and the number < 100 grains, it meets the set requirements. Continue to start the two-roll mill, set the temperature inside the rolls of the two-roll mill to 40°C and the rotation speed to 25 r / min. When turning and mixing in the two-roll mill, set the number of thin passes to 2, the number of triangular bales to 3, and the number of empty passes to 4, and then discharge the film according to the specifications of width: 100 - 200 mm and thickness: 5 - 10 mm.

[0021] Furthermore, in step S4, park the film obtained after the initial mixing in an environment with a room temperature of 23° and a humidity of 50%, and the static parking time lasts for at least 8 hours.

[0022] Furthermore, in step S5, during secondary refining, set the rotation speed of the internal mixer to 45 r / min, the refining temperature to 120°C ± 10°C, and the refining time to 3 - 5 min.

[0023] The width of the film discharged after sufficient secondary mixing is 100 - 200 mm, and the thickness is 5 - 10 mm.

[0024] Furthermore, in step S6, during the third mixing, set the rotation speed of the internal mixer to 30 r / min, the mixing temperature to 60°C ± 10°C, and the mixing time to 2 - 3 min.

[0025] Confirm that there are no impurities and foreign objects on the surface of the mixed rubber compound, and the mixing is completed.

[0026] Furthermore, the obtained product performance: hardness is between 70±5 Shore A, tensile strength ≥10 MPa, elongation at break ≥300%, meets the requirements of flame retardancy UL94-V0 grade, hardness change during hot air aging at 125°C×72 h meets ±10 Shore A, tensile strength change rate ≤ -25%, environmental protection meets EU ROHS and REACH, elongation at break change rate ≤ -25%, and odor level ≤ 3 levels.

[0027] Through the above technical solutions, compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. The green environmental protection flame retardant and low odor automotive sealing strip compound provided by the present invention fully considers the advantages of ethylene propylene rubber such as excellent aging resistance, ozone resistance, low temperature resistance and insulation, etc., but its disadvantage of poor flame retardancy. A halogen-free flame retardant MM-X1 is added to the material components. The combination of ethylene propylene rubber and the halogen-free flame retardant MM-X1 can form a composite material with better performance, improve the flame retardancy of the product, improve the heat resistance and cold resistance of the product, improve the aging resistance of the product, and extend its service life;

[0029] 2. The halogen-free flame retardant MM-X1 added to the green environmental protection flame retardant and low odor automotive sealing strip compound provided by the present invention realizes the flame retardant effect through elements such as phosphorus, nitrogen and silicon. Since it does not contain halogens, the halogen-free flame retardant will not produce toxic hydrogen halide gas during combustion, has a low odor, is more friendly to the environment and human body, and meets the EU environmental protection standards such as ROHS and REACH;

[0030] 3. The green environmental protection flame retardant and low odor automotive sealing strip compound provided by the present invention also includes filling and reinforcing materials, functional additives, vulcanizing and accelerating agents. By reasonable selection and combination of each component, it takes into account the requirements of multiple aspects such as green environmental protection, flame retardancy, low odor and good physical and mechanical properties, and is suitable for the production of automotive sealing strips;

[0031] 4. The preparation method of the green environmental protection flame retardant and low odor automotive sealing strip compound provided by the present invention mixes in stages to avoid the out-of-control reaction that may be caused by mixing all raw materials at one time. The step-by-step mixing enables the rubber compound to adapt to different processing conditions at different stages. This gradual way avoids problems such as sudden change in viscosity of the rubber compound and processing difficulties caused by processing all raw materials at one time, improves production efficiency and product quality stability, and is conducive to the smooth progress of large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The present invention will be further described below with reference to the drawings and embodiments.

[0033] Figure 1 It is a schematic flow chart of the preparation method provided by the present invention. Detailed Embodiments

[0034] The present invention will now be further described in detail with reference to the accompanying drawings.

[0035] As described in the background art, in the current production technology of automotive sealing strip compound for improving the combustion resistance performance, most of them cause greater pollution to the environment while meeting the requirement of improving the combustion resistance performance. Therefore, the relevant technical personnel of this application considered using the halogen-free flame retardant MM-X1 as the flame retardant. It is a flame retardant without halogen (chlorine CL, bromine Br), which is widely used in various materials to reduce the fire risk. Halogen-free flame retardants mainly achieve the flame retardant effect through elements such as phosphorus, nitrogen, and silicon. Since they do not contain halogen, halogen-free flame retardants will not produce toxic hydrogen halide gas during combustion, being more friendly to the environment and human body. Its flame retardant principle is that during the combustion process, the phosphorus-based flame retardant will form a protective carbon layer to isolate oxygen and heat sources, thereby inhibiting the spread of the flame. At the same time, by releasing non-combustible gases such as nitrogen during combustion, the concentration of combustible gases is reduced, thus achieving the flame retardant effect.

[0036] Therefore, the green and environmentally friendly flame retardant automotive sealing strip compound provided by this application, which mixes and uses ethylene-propylene rubber and the halogen-free flame retardant MM-X1, can greatly improve the performance, making the product more flame retardant, ozone resistant, low odor, environmentally friendly, and having good heat resistance.

[0037] In addition to ethylene-propylene rubber and the halogen-free flame retardant MM-X1, which are two relatively important and innovative components in the compounding ratio of this application's compound, the components of the compound also include the filler and reinforcing material - carbon black N550, the functional additives - zinc oxide ZNOA, stearic acid SA, softening plasticizer PIONIER1535, antioxidant RD, and antioxidant 4010NA, and the vulcanizing and accelerating agents - vulcanizing agent S-80HE and accelerator combination.

[0038] The main component of carbon black N550 is C (carbon). In addition, there are small amounts of compounds of H (hydrogen), O (oxygen), and S (sulfur) on the surface of carbon black, such as: SO 2 (sulfur dioxide), H 2 S (hydrogen sulfide), H 2 SO 4 (sulfuric acid) and other compounds. Carbon black can improve the physical and mechanical properties of rubber in rubber, such as: improving the tensile strength, wear resistance, and aging resistance; in addition, these compounds on the surface of carbon black will react with oxygen in the air in a high-temperature environment to generate active oxygen-containing functional groups, and these functional groups will affect the chemical properties of carbon black, changing its acid-base PH value. If the PH is high, it is alkaline, which will accelerate the vulcanization speed of the rubber compound; if the PH is low, it is acidic, reducing the vulcanization speed of the rubber compound.

[0039] The softening plasticizer PIONIER1535 is an organic compound, mainly composed of n-docosane (C 22 H 46 ) and n-octadecane (C 28 H 58 ). It can reduce the viscosity of rubber in rubber, improve the fluidity and processability of the rubber compound, and does not chemically react with other chemical substances and raw materials in the rubber, physically improving the fluidity of the rubber compound.

[0040] The combination of antioxidant RD ((C 12 H 15 N) n ) and antioxidant 4010NA (C 15 H 18 N 2 ) mainly plays an antioxidant effect in rubber. It can capture the free radicals generated during the rubber aging process, prevent the progress of the free radical chain reaction, and at the same time can decompose the peroxides in the rubber, further improving its antioxidant effect.

[0041] Due to the large differences in unsaturation and polarity of ethylene-propylene rubber, zinc oxide ZNOA is used as a vulcanization activator. Its solubility in the two rubbers is good, which can improve the vulcanization efficiency. Stearic acid SA helps to activate zinc oxide ZNOA and improve the processing fluidity of the rubber compound. The function of vulcanizing agent S-80HE is to form a cross-linked structure between rubber molecules, thereby improving the strength, hardness, wear resistance, oil resistance and other properties of the rubber. The accelerator combination can accelerate the speed of the vulcanization reaction and shorten the vulcanization time.

[0042] Zinc oxide ZNOA, stearic acid SA, and the vulcanizing and accelerating agents in the formula interact with each other and synergistically enhance during rubber vulcanization. That is, during the vulcanization process: first, the interaction of sulfur, accelerator, and activator increases the solubility of zinc oxide ZNOA in the rubber compound, activates the accelerator, and makes the accelerator react with sulfur to form an intermediate product with greater activity; then further initiates the rubber molecular chain to generate cross-linkable rubber macromolecular free radicals. The second stage is the cross-linking reaction, that is, the cross-linkable free radicals react with the rubber molecular chain to form cross-links. The third stage is the network formation stage. The cross-linking reaction has been completed, and the initially formed cross-links undergo shortening, rearrangement, and cleavage reactions. Finally, the network tends to be stable, and a vulcanized rubber with a relatively stable network is obtained.

[0043] Regarding the accelerator combination, the present application provides a preference, which is a mixture of ZDTP-50, ZDEC-70, ZBEC-70, CBS-80, and TMTD-75. Through these synergistic effects of the various component raw materials in the rubber compound, the various components in the rubber formula can cooperate with each other, endowing the rubber product with excellent physical and mechanical properties and processing properties.

[0044] After determining the various components for preparing the green environmental protection flame-retardant and low-odor automotive sealing strip compound, the present application also optimizes the mass parts of the components. Specifically, according to mass parts, each component includes: ethylene-propylene rubber: 100 parts, carbon black N550: 10 - 30 parts, halogen-free flame retardant MM-X1: 30 - 50 parts, zinc oxide ZNOA: 5 parts, stearic acid SA: 1 part, softening plasticizer PIONIER1535: 30 parts, antioxidant RD: 1 part, antioxidant 4010NA: 1 part, vulcanizing agent S-80HE: 1.5 parts, and the mass parts of ZDTP-50, ZDEC-70, ZBEC-70, CBS-80, and TMTD-75 in the accelerator combination are all 1.2 parts.

[0045] Then the present application provides a method for preparing the green environmental protection flame-retardant and low-odor automotive sealing strip compound, as Figure 1 shown. It adopts a multi-stage mixing process technology. During the multi-stage mixing process, the dispersibility and uniformity of the rubber compound are controlled each time; after the first-stage mixing, the surface impurities of the rubber compound are inspected to judge the dispersion situation, and after the second-stage refining, the sheet is taken out again to observe the appearance. After the third-stage mixing, it is checked whether there are impurities and foreign matters on the surface of the rubber compound to judge the final mixing effect; through multi-link monitoring, the consistency of the quality of each batch of products is ensured, the defective rate is reduced, and the overall quality of the product is improved.

[0046] Specifically, it includes the following steps:

[0047] Step S1, put the ethylene-propylene rubber into a Banbury mixer for mixing, set the rotation speed of the Banbury mixer to 40 r / min, and the initial mixing temperature to 35 °C; as the mixing time extends, after mixing for 60 - 90 seconds, the mixing temperature reaches 100 °C ± 10 °C, and the ethylene-propylene rubber forms a uniform rubber compound matrix.

[0048] Step S2, put carbon black N550, halogen-free flame retardant MM-X1, zinc oxide ZNOA, stearic acid SA, softening plasticizer PIONIER1535, antioxidant RD, and antioxidant 4010NA into the rubber compound matrix, and put them into the Banbury mixer all at once for continuous mixing. The mixing rotation speed is 40 r / min, and the mixing time is 150 - 180 seconds. The mixing temperature reaches 150 - 160 °C, and each component raw material is evenly dispersed in the rubber compound matrix; at this stage, because the vulcanization accelerator is not added, the chemical reaction does not occur among the component raw materials, but they are just evenly mixed together.

[0049] Step S3. After the initial mixing is completed, discharge the mixed rubber compound from the internal mixer. After discharging, use a thermometer to test whether the temperature is between 140°C and 150°C (the purpose is to determine whether the rubber compound has reached the required temperature. Only when it reaches the required temperature can the rubber compound be fully and evenly mixed). Visually observe whether there are impurities or foreign objects on the surface of the colloid (the particle size of surface impurities ≤ 3 mm, and the number < 100 grains). If there are no surface impurities, it is judged whether the component materials have been fully dispersed; then use a two-roll mill to re-mill the mixed rubber compound matrix after full dispersion. The temperature inside the rolls of the two-roll mill is 40°C, and the rotation speed is 25 r / min. During re-milling: thin pass 2 times, make triangular bales 3 times, and empty down 4 times. Then, produce rubber sheets according to the specifications of width: 100 - 200 mm, thickness: 5 - 10 mm for standby.

[0050] Steps S1 - S3 are the first-stage mixing. First, form a uniform rubber compound matrix from ethylene-propylene rubber, and then add various components such as carbon black and halogen-free flame retardants. At this time, since the vulcanization accelerator is not added, the components are only physically mixed and can be more evenly dispersed in the rubber compound matrix under the high-speed stirring of the internal mixer. For example, the uniform dispersion of carbon black can effectively enhance the strength and wear resistance of the rubber, and the uniform distribution of the halogen-free flame retardant can ensure the consistency of the flame retardant performance of the rubber compound.

[0051] Step S4. Subject the rubber sheet obtained after the initial mixing to a parking treatment. Specifically, park the rubber sheet obtained after the first-stage mixing in an environment with a room temperature of 23° and a humidity of 50% and let it stand still for at least 8 hours; the parking treatment allows the molecular chains of the rubber compound to relax and eliminates internal stress, making the molecular arrangement more regular. When re-mixing, under suitable temperature and rotation speed conditions, the molecular chains can better entangle and interweave with each other to form a more stable network structure, which helps to improve the physical properties such as the tensile strength and resilience of the rubber, enabling the automotive sealing strip to better maintain its shape and sealing effect during long-term use.

[0052] Step S5. After parking is completed, put the rubber sheet into the internal mixer with the set mixing parameters again for the second-stage refining. The second-stage refining conditions are: mixing temperature: 120°C ± 10°C, rotation speed: 45 r / min, time: 3 - 5 min. When the rubber compound is re-mixed under these conditions, the rubber compound is further homogenized; during the refining process, the pressure and rotor rotation speed of the internal mixer can be appropriately adjusted to ensure that the rubber compound is subjected to sufficient shearing and kneading effects;

[0053] After sufficient mixing, produce rubber sheets again. The specifications for this rubber sheet production are still the same as those for the first rubber sheet production, with a width of 100 - 200 mm and a thickness of 5 - 10 mm. This rubber sheet production specification is convenient for placing the rubber compound and saves space; after two times of mixing and rubber sheet production, the raw material components in the rubber compound have been completely dispersed, making its surface smooth and beautiful, and the obtained rubber sheet is for standby.

[0054] Compared with the existing mixing process, the present application adds the secondary refining provided by steps S4 - S5 to improve the compatibility between ethylene - propylene rubber and the halogen - free flame retardant, further homogenize the rubber compound at a slightly lower temperature and speed, make various compounding agents diffuse more fully at the molecular level, and enhance the stability of material properties.

[0055] Then, the third - stage mixing is carried out in step S6. The film obtained after the secondary mixing is put into an internal mixer together with vulcanizing agent S - 80HE, accelerator ZDTP - 50, accelerator ZDEC - 70, accelerator ZBEC - 70, accelerator CBS - 80, and accelerator TMTD - 75 for the third - stage mixing. During mixing, the following parameters are set: rotation speed 30 r / min, temperature 60°C ± 10°C, time 2 - 3 min. After mixing for the set mixing time, the rubber compound can be discharged from the internal mixer. Observe whether there are impurities or foreign objects on the surface of the discharged rubber compound, or observe the dispersion. If there are no impurities or foreign objects, etc., the rubber compound has been fully and evenly mixed, and the mixing is completed. The vulcanizing agent and accelerators are added only during the third - stage mixing. At this time, the rubber compound already has a good uniformity basis, can carry out the vulcanization reaction smoothly under suitable conditions, is convenient for accurately controlling the vulcanization process, and improves the production efficiency and the stability of product quality.

[0056] The mixing is carried out in stages, enabling the rubber compound to adapt to different processing conditions at different stages. In the first - stage mixing, a large amount of raw materials are initially mixed at a relatively high temperature and speed. In the second - stage refining, the uniformity is further refined at a slightly lower temperature and speed. In the third - stage mixing, the vulcanizing agent, etc. are added at a low temperature and low speed for the final mixing. This step - by - step method accurately controls the vulcanization process, avoids problems such as sudden changes in the viscosity of the rubber compound and processing difficulties caused by processing all raw materials at once. Moreover, through multi - link monitoring, the consistency of the quality of each batch of products is ensured, the defective rate is reduced, the overall quality of the products is improved, and it is conducive to the smooth progress of large - scale production.

[0057] The following combines Examples 1 - 3 to verify the effects of the rubber compound prepared by the preparation method provided by the present application.

[0058] The preparation method of the green environmental - protection flame - retardant and low - odor automotive sealing strip rubber compound used in Examples 1 - 3 is as follows:

[0059] In the first - stage mixing, ethylene - propylene rubber is put into an internal mixer and mixed for 60 - 90 seconds, then carbon black N550, halogen - free flame retardant MM - X1, zinc oxide ZNOA, stearic acid SA, softening plasticizer PIONIER1535, antioxidant RD, and antioxidant 4010NA are added and mixed. After mixing, the sheet is taken out and reserved.

[0060] In the second - stage mixing, after the material obtained from the above - mentioned first - stage mixing is parked for at least 8 hours, it is put into the internal mixer again for secondary refining. After sufficient mixing, the sheet is taken out and reserved.

[0061] The third-stage mixing: Add vulcanizing agent and the remaining raw materials to the materials after the upper-stage mixing, conduct mixing, ensure sufficient mixing, clean and then mix again. After sufficient dispersion, take out the rubber to obtain a green, environmentally friendly, flame-retardant and low-odor rubber material for automotive sealing strips.

[0062] According to the above preparation method, three formulation components are provided (Table 1), and at the same time, the preparation method conditions of the three formulation components are given (Table 2) to obtain the products of Examples 1-3. Finally, corresponding performance tests are carried out on the products of Examples 1-3 to obtain performance parameters (Table 3).

[0063] Table 1 Formulation components of Examples 1-3

[0064]

[0065] Table 2 Preparation process conditions of Examples 1-3

[0066]

[0067] Table 3 Performance parameters of the rubber compounds prepared in Examples 1-3

[0068]

[0069] As can be seen from Table 3, for the rubber compounds obtained in Examples 1-3, the hardness is between 70±5 Shore A, the tensile strength ≥10 MPa, the elongation at break ≥300%, meeting the requirements of the flame retardancy UL94-V0 grade. For the hot air aging at 125°C×72 h, the hardness change is ±10 Shore A, the change rate of tensile strength ≤ -25%, and the change rate of elongation at break ≤ -25%. The environmental protection meets the requirements of EU ROHS and REACH, and the odor level ≤ 3. It is thus determined that the products of Examples 1-3 have good flame retardant resistance, strong thermal aging resistance, are green and environmentally friendly, and have low odor. This application greatly improves the flame retardant resistance and odor improvement ability of ethylene-propylene rubber, and can meet the performance requirements of customers for green, environmentally friendly, flame-retardant and low-odor automotive sealing strips.

[0070] Those skilled in the art of this technology can understand that unless otherwise defined, all terms (including technical terms and scientific terms) used here have the same meaning as the general understanding of those of ordinary skill in the art to which this application belongs. It should also be understood that terms such as those defined in a general dictionary should be understood to have a meaning consistent with the meaning in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless defined as here.

[0071] The meaning of "and / or" described in this application refers to the situation where each exists alone or both exist simultaneously.

[0072] As used in this application, "connection" can mean either a direct connection between components or an indirect connection between components through other components.

[0073] Inspired by the above-described ideal embodiments of the present invention, through the above description, relevant staff can make various changes and modifications completely within the scope without departing from the technical idea of this invention. The technical scope of this invention is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A green, flame-retardant, low-odor automotive sealing strip rubber compound, characterized by: According to the mass percentage, the components include: ethylene propylene rubber: 100 parts, carbon black N550: 10-30 parts, halogen-free flame retardant MM-X1: 30-50 parts, zinc oxide ZNOA: 5 parts, stearic acid SA: 1 part, softening plasticizer PIONIER1535: 30 parts, antioxidant RD: 1 part, antioxidant 4010NA: 1 part, vulcanizing agent S-80HE: 1.5 parts and accelerator combination; The accelerator combination is a mixture of ZDTP-50, ZDEC-70, ZBEC-70, CBS-80 and TMTD-75, and the mass fraction of each component in the accelerator combination is 1.2 parts.

2. The green, environmentally friendly, flame-retardant, low-odor automotive sealing strip rubber compound according to claim 1, characterized in that: The grades of EPDM rubber used are EPDM3092PM, Keltan2470C or EPDM5601.

3. The method for preparing the green, flame-retardant, low-odor automobile sealing strip rubber compound according to claim 1, characterized in that: The specific steps include: Step S1, putting the ethylene-propylene rubber into an internal mixer for internal mixing until the ethylene-propylene rubber forms a uniform rubber matrix; Step S2, adding carbon black N550, halogen-free flame retardant MM-X1, zinc oxide ZNOA, stearic acid SA, softening plasticizer PIONIER1535, antioxidant RD and antioxidant 4010NA into the rubber matrix, and performing initial mixing with the ethylene-propylene rubber; Step S3, after the initial mixing is completed, the mixed rubber material is discharged from the internal mixer, and its state is evaluated. If it meets the set requirements, the mixed rubber material is put into the open mixer, and the mixed rubber material is re-mixed and then the film is produced for standby use; Step S4, allowing the film obtained after the initial mixing to stand for a preset time; Step S5, putting the film after parking into the internal mixer again for secondary refining, and producing the film after the secondary mixing is sufficient; Step S6, putting the film obtained after the secondary mixing together with the vulcanizing agent S-80HE, the accelerator ZDTP-50, the accelerator ZDEC-70, the accelerator ZBEC-70, the accelerator CBS-80 and the accelerator TMTD-75 into an internal mixer for the third mixing. After the third mixing is completed, the mixed rubber is discharged from the internal mixer, the state of the mixed rubber is confirmed, and the mixing is completed.

4. The method for preparing the green, environment-friendly, flame-retardant and low-odor automobile sealing strip rubber compound according to claim 3, characterized in that: In step S1, the speed of the internal mixer is set to 40 r / min, and the initial mixing temperature is set to 35° C. After the internal mixing is continued for 60-90 seconds, the mixing temperature reaches 100° C.±10° C.; In step S2, during the initial mixing, the speed of the internal mixer is continued to be set to 40 r / min, and after the mixing continues for 150-180 seconds, the internal mixing temperature reaches 150-160° C.; In step S3, after the initial mixing is completed, the temperature of the mixed rubber material discharged from the internal mixer is tested with a thermometer. If the temperature is between 140°C and 150°C, and there are no impurities on the surface of the film or the particle size of the surface impurities is ≤3mm and the number is <100, it meets the set requirements; continue to start the open mixer, set the temperature inside the roller of the open mixer to 40°C and the speed to 25r / min; when refining in the open mixer, set thin pass 2 times, triangle package 3 times, empty 4 times, and then discharge the film according to the specifications of width: 100-200mm, thickness: 5-10mm.

5. The method for preparing the green, environment-friendly, flame-retardant and low-odor automobile sealing strip rubber compound according to claim 3, characterized in that: In step S4, the film obtained after the initial mixing is placed in an environment with a room temperature of 23° and a humidity of 50% for at least 8 hours.

6. The method for preparing the green, environment-friendly, flame-retardant and low-odor automobile sealing strip rubber compound according to claim 3, characterized in that: In step S5, during the secondary refining, the speed of the internal mixer is set to 45 r / min, the internal mixing temperature is set to 120° C.±10° C., and the internal mixing time is set to 3-5 min; After the secondary mixing is sufficient, the film width is 100-200mm and the thickness is 5-10mm.

7. The method for preparing the green, environment-friendly, flame-retardant and low-odor automobile sealing strip rubber compound according to claim 3, characterized in that: In step S6, during the third mixing, the speed of the internal mixer is set to 30 r / min, the internal mixing temperature is set to 60° C.±10° C., and the internal mixing time is set to 2-3 min; Confirm that there are no impurities or foreign matter on the surface of the mixed rubber, and the mixing is completed.

8. The method for preparing the green, environment-friendly, flame-retardant and low-odor automobile sealing strip rubber compound according to claim 3, characterized in that: The obtained product performance: hardness is between 70±5Shore A, tensile strength ≥10MPa, elongation at break ≥300%, in line with the flame retardancy UL94-V0 grade requirements, hot air aging 125℃×72h hardness change meets ±10Shore A, tensile strength change rate ≤-25%, environmental protection meets EU ROHS and REACH, elongation at break change rate ≤-25%, odor ≤3 levels.

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