Low-VOCs environment-friendly PP / EPDM thermoplastic elastomer for automotive trim

Abstract

The invention discloses a low-VOCs (volatile organic compounds) environment-friendly PP (polypropylene) / EPDM (ethylene propylene diene monomer) thermoplastic elastomer for automotive interiors. In the aspect of raw material application, traditional hydrogen sulfide and thiol are abandoned, a phenolic resin vulcanization system is adopted, phenolic resin in the system reacts with a zinc oxime vulcanizing agent, crosslinking curing of EPDM can be promoted, a net-shaped structure is formed to fix sulfide, water vapor instead of VOCs is released when phenolic resin is vulcanized, and the problem that the thermoplastic elastomer releases VOCs is fundamentally solved. During polymer plastification, polypropylene glycol adipate is used for replacing traditional phthalate, the volatility of the thermoplastic elastomer is reduced by 80%, and generation of halogenated hydrocarbon VOCs due to thermal decomposition is avoided. Meanwhile, a KH-560 silane coupling agent is used for modifying the surface, the PP / EPDM interface bonding force is enhanced, and accumulation of VOCs in phase interface gaps is reduced. 13X type molecular sieve microporous zeolite is added into a blending system, residual VOCs are physically adsorbed by utilizing a porous structure, and VOCs in the thermoplastic elastomer are greatly reduced through the common synergistic effect of the mechanisms, so that the effect of preparing low-VOCs products is achieved.

Description

Technical Field

[0001] The present invention belongs to the field of environmental protection automotive interior materials engineering, and particularly relates to a low-VOCs environmental protection PP / EPDM thermoplastic elastomer for automotive interiors. Background Art

[0002] New energy vehicles have put forward higher requirements for interior materials, such as lightweight, weather resistance and low fogging characteristics. The global emphasis on circular economy has promoted the development of TPE towards high recyclability. Such materials not only comply with the EU's plastic recycling policy in 2025, but also can reduce the carbon credit pressure on automobile manufacturers. There is a natural contradiction in the blending of polyphenylene ether and ethylene propylene diene monomer (EPDM). Among them, PP has strong polarity and EPDM is non-polar, and the poor compatibility between the two leads to weak interfacial bonding force. Although traditional compatibilizers can improve the dispersibility, they will reduce the heat resistance of the material.

[0003] Traditional sulfur vulcanization systems have two major defects. One is the release of hydrogen sulfide during the vulcanization process, and the other is the poor thermal stability of the vulcanized rubber network. Although phenolic resin vulcanization can avoid sulfur-based by-products, there are problems such as slow curing speed and insufficient compatibility with EPDM at temperatures above 160°C. How to maintain the thermal stability of the material while reducing VOCs has become the key. And the sources of VOCs are complex and may come from vulcanization by-products, plasticizer volatilization, and filler adsorption residues. Under the current technology, single adsorption technology can only treat residual VOCs and cannot inhibit the release from the source. It is necessary to combine formula optimization and process improvement to form a synergistic solution.

[0004] The technical background of the low-VOCs environmental protection PP / EPDM thermoplastic elastomer for automotive interiors is the result of the combined action of upgraded environmental protection regulations, the outbreak of new energy vehicle demand, and the progress of materials science. Through the collaborative innovation of vulcanization system innovation, formula greening, interface modification and process optimization, this patent has achieved breakthroughs in VOCs control, mechanical properties and processing efficiency of the material, solved the problem of difficult removal of VOCs in thermoplastic elastomers, and become a key support for automotive lightweight and sustainable development. Summary of the Invention

[0005] In order to solve the problem of difficult removal of VOCs in thermoplastic elastomers, this patent provides a low-VOCs environmental protection PP / EPDM thermoplastic elastomer for automotive interiors.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A low-VOCs environmental protection PP / EPDM thermoplastic elastomer for automotive interiors, comprising the following weight components:

[0008] 70 - 80 g of polyphenylene ether, 5 - 8 g of low - density polyvinyl alcohol (molecular weight < 100,000), 30 - 40 g of ethylene - propylene - diene monomer rubber, 8 - 10 g of p - tert - butylphenolic resin, 0.8 - 1 g of zinc oxime dimethyldithiocarbamate, 5 - 8 g of polypropylene glycol adipate, 3 - 5 g of silane coupling agent KH - 560, 2 - 5 g of 13X molecular sieve, 20 - 25 g of silica white.

[0009] Preferably, the raw materials abandon sulfur and thiazole - type accelerator systems that are prone to produce sulfur - containing VOCs such as hydrogen sulfide and mercaptans, and instead use a phenolic resin vulcanization system to reduce the sulfur - containing ratio from the source.

[0010] Preferably, the phenolic resin releases water vapor instead of organic volatiles during vulcanization, and the decomposition products of the oxime - type vulcanizing agent are nitrogen and low - toxicity organic substances.

[0011] Preferably, the phenolic resin and zinc oxime vulcanizing agent are used as a vulcanization system, which promotes the cross - linking and curing of EPDM to form a network structure, blocks the sulfur - containing substances in the raw materials at the structural level, and simultaneously improves the mechanical properties.

[0012] Preferably, the high - molecular - weight polyester plasticizer is replaced by polypropylene glycol adipate for traditional phthalate esters. Its boiling point is higher than 300 °C and the volatility is reduced by 80%. The organic phosphorus - type stabilizer triphenyl phosphite is selected to replace the traditional halogen - containing stabilizer to avoid the generation of halogenated hydrocarbon VOCs during thermal decomposition.

[0013] Preferably, introducing 5% - 8% of low - molecular - weight polyvinyl alcohol into PP, the hydroxyl groups form hydrogen - bond networks with the phenolic resin, further enhancing the stability of the EPDM cross - linked structure, and adsorbing aldehyde and ketone - type VOCs while improving the strength of the system.

[0014] Preferably, the silane coupling agent KH - 560 modifies the surface of the filler, enhances the interfacial bonding force between PP / EPDM, reduces the accumulation of VOCs in the phase - interface gaps, and simultaneously, the vacuum devolatilization technology extracts the vulcanization by - products in real - time to further reduce the residue.

[0015] Preferably, adding 2% - 3% of 13X molecular sieve microporous zeolite with a particle size between 1 - 2 μm to the blending system, and using its porous structure to physically adsorb the residual VOCs.

[0016] Preferably, the 13X activated molecular sieve is used to adsorb the residual moisture or volatile impurities, improve the purity of the system, and simultaneously play a catalytic role during the vulcanization process.

[0017] Preferably, the tensile strength of the thermoplastic elastomer is between 15 - 18 MPa, the elongation at break is greater than 350%, and after aging at 120 °C for 168 h, the tensile strength retention rate is greater than 85%, which is attributed to the thermal stability of the phenolic resin vulcanization network.

[0018] Advantages of a polypeptide mixture for improving sleep based on the synergistic action of multiple targets in the present invention:

[0019] 1. In this patent, phenolic resin and zinc oxime vulcanizing agent are used to replace the traditional sulfur system, eliminating the generation of sulfur-containing VOCs such as hydrogen sulfide and mercaptans from the source. Only water vapor is released during the vulcanization process of phenolic resin, and the decomposition products of zinc oxime vulcanizing agent are nitrogen and low-toxic organic substances, meeting the health standards of automotive interior materials.

[0020] 2. In this patent, PVA and PP are blended to form polar microdomains, which can physically capture aldehyde and ketone VOCs. Among them, 13X molecular sieve is uniformly dispersed in the matrix, and small molecule volatiles are adsorbed through the microporous structure. The dual action reduces TVOC by more than 50%. The silane coupling agent KH-560 modifies the surface of the filler, enhancing the interfacial bonding force between PP / EPDM and reducing the accumulation of VOCs in the phase interface gap. At the same time, the vacuum devolatilization technology extracts the vulcanization by-products in real time, further reducing the residue.

[0021] 3. In this patent, the dynamic vulcanization time is shortened to 8 - 10 minutes, and excellent dispersion is still maintained under the condition that the screw speed is increased to 150 r / min, increasing the production capacity of a single set of equipment by 30% compared with the traditional process. Although the raw material cost increases by about 8% due to the use of high-performance vulcanizing agent and modifying additives, the key performance indicators of the improved product meet the standards of high-end automotive interior materials after omitting the investment in end-of-pipe waste gas treatment equipment such as activated carbon adsorption, and the product added value is increased by more than 40% compared with the conventional grade.

[0022] 4. In this patent, using polypropylene adipate to replace the traditional phthalate can effectively avoid the generation of halogenated hydrocarbons caused by thermal decomposition, forming hydrogen bonds and van der Waals forces in the polar groups of PPA and TPE polymers. Under this force, the interaction between molecular chains, the softness and elasticity of the material will be reduced. PPA can also act as a low-volatility and high-molecular-weight polyester plasticizer in the system, making the polymer compatibility more excellent and making it not easy to migrate to the surface and precipitate.

[0023] 5. In this patent, a purging device is used. This device lasts for 2.5 hours in an environment with a temperature of 70 °C to achieve the dissipation of VOCs as much as possible. A large amount of aldehydes and phenols are contained in VOCs, and a large amount of aldehydes will volatilize and phenols will be oxidized and volatilized under the action of the purging device. Description of the Drawings

[0024] Figure 1 It is a flow chart of a low-VOCs environmentally friendly PP / EPDM thermoplastic elastomer for automotive interior in the present invention; Detailed Embodiments

[0025] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0026] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, the elements defined by the statement "including..." do not exclude the existence of additional identical elements in the process, method, article or device including the said elements.

[0027] Reference Figure 1 , Example 1 details the method for preparing a low-VOCs environmentally friendly PP / EPDM thermoplastic elastomer for automotive interiors.

[0028] Example 1

[0029] This example provides a low-VOCs environmentally friendly PP / EPDM thermoplastic elastomer for automotive interiors, which is suitable for environmentally friendly automotive interiors. The following are the implementation details:

[0030] Experimental raw materials:

[0031] 70 g of polyphenylene ether, 5 g of low-density polyvinyl alcohol, 30 g of ethylene propylene diene monomer rubber, 8 g of p-tert-butylphenolic resin, 0.8 g of zinc oxime dimethyldithiocarbamate, 5 g of poly(propylene adipate), 3 g of silane coupling agent KH-560, 2 g of 13X molecular sieve, 20 g of silica white.

[0032] Experimental purpose:

[0033] To prepare a low-VOCs environmentally friendly PP / EPDM thermoplastic elastomer for automotive interiors.

[0034] Experimental steps:

[0035] S1: Add 20 g of silica white into a 100 mL three-necked flask, heat up to 80 °C and stir at a rotation speed of 200 r / min. Slowly dropwise add 3 g of KH-560 ethanol solution, react at a constant temperature for 30 min, remove ethanol by vacuum distillation. After the obtained modified silica white is cooled, sieve it through a 100-mesh sieve and reserve for use;

[0036] S2: Add 8 g of phenolic resin and 0.8 g of zinc oxime vulcanizing agent into an agate mortar, add 5 g of polyester plasticizer and grind until there are no particles, forming a uniform paste-like vulcanizing agent masterbatch. Weigh 70 g of PP particles and 5 g of PVA powder, add them into a high-speed mixer with a rotation speed of 1000 r / min, mix at room temperature for 5 min to make PVA uniformly dispersed in PP;

[0037] S3: Preheat the twin-screw extruder, set the temperature of each section as follows: the feeding section is 120 °C, the melting section is 140 °C, the vacuum section is 160 °C, and the die head is 170 °C. Add the modified PP / PVA mixture and 18 g of modified silica white from the main feeding port, and at the same time add polyester plasticizer through the side feeding port at a speed of 5 g / min. Control the screw rotation speed at 80 r / min and the plasticizing time at 10 min until the material at the discharge port is in a uniform semi-transparent state;

[0038] S4: After the matrix is plasticized, add 30 g of EPDM and the vulcanizing agent masterbatch from the side feeding port. At the same time, turn on the vacuum system, increase the screw rotation speed to 150 r / min, maintain the temperature of the vulcanizing section at 170 °C. When the blended material enters 20 cm before the vacuum section, uniformly add 2 g of activated molecular sieve through a loss-in-weight feeder and blend it with the material until extrusion;

[0039] S5: Cut the extruded strip into 5-cm small sections, put them into a customized purging device, introduce high-purity nitrogen at a flow rate of 8 L / min, purge at 70 °C for 2.5 h. Transfer the purged sample to a forced-air oven, set the temperature at 90 °C and the humidity at 25%, bake for 4 h, take it out and seal it in an aluminum foil bag and cool it to room temperature;

[0040] S6: Weigh 2 g of the sample and put it into a headspace vial, seal it and equilibrate at 80 °C for 30 min, and detect the VOCs components and their concentrations in the headspace gas by GC-MS.

[0041] Experimental results: Details are shown in Table 1.

[0042] Table 1: Test results of Example 1

[0043] Formaldehyde Styrene Phenol Methanol Acetaldehyde Benzene series Hydrogen sulfide Concentration <![CDATA[0.05mg / m 3 > <![CDATA[0.005mg / m 3 > <![CDATA[0.02mg / m 3 > <![CDATA[0.2mg / m 3 > <![CDATA[0.01mg / m 3 > <![CDATA[0.05mg / m 3 > <![CDATA[0.001mg / m 3 >

[0044] Among them, formaldehyde is decomposed from phenolic resin pyrolysis in S2 and S3. Phenol is the product of phenolic resin remaining in the system due to high-temperature pyrolysis. Styrene and benzene series compounds are caused by the degradation of PP in a high-temperature environment. Methanol and acetaldehyde are due to the residue and pyrolysis of PVA. And the by-product caused by the vulcanization of EPDM results in the generation of hydrogen sulfide. In S3, due to the temperature of the melting section being 140°C, substances such as formaldehyde, styrene, and methanol are released in large quantities. In S5, hot air at 70°C is used to blow out volatile substances such as methanol and acetaldehyde in the system to achieve the removal of VOCs.

[0045] Comparative Example 1

[0046] This example provides a preparation process of styrene-butadiene-styrene block copolymer, which is applicable to outdoor application scenarios and includes the following implementation contents:

[0047] Experimental purpose:

[0048] Prepare styrene-butadiene-styrene block copolymer

[0049] Experimental raw materials:

[0050] Styrene, butadiene, n-butyllithium, cyclohexane, methanol, hindered phenols, calcium carbonate

[0051] Experimental steps:

[0052] S1: Under a nitrogen atmosphere, cyclohexane is added to the reaction kettle as a solvent, styrene monomer and n-butyllithium are added, the reaction system is controlled at 70°C for 2 hours, butadiene monomer is added to the reaction kettle, and the temperature of the reaction system is continuously maintained at 70°C for 2 hours. Then styrene monomer is added to the reaction system, and the reaction system is still controlled at 70°C for 2 hours. After polymerization is completed, terminator methanol is added;

[0053] S2: The polymerization reaction liquid is transported to a vacuum devolatilization device, the system pressure is reduced to below 10 kPa by a three-stage vacuum pump group, the jacket is heated to 120°C, so that the cyclohexane solvent evaporates and condenses rapidly under low boiling point conditions and is recovered. After removing the main solvent, the residual polymer is treated with steam blowing at 150°C, and superheated steam is used to strip the trace solvent adsorbed on the surface of the polymer until the solvent residue detected by on-line gas chromatography < 50 ppm;

[0054] S3: The devolatilized SBS polymer is transported to a twin-screw extruder, the barrel temperature is set at 200°C, the polymer is melted and plasticized through the shear action of the screw barrel, the molten material is extruded into a strip with a diameter of 3 mm through a hanger die head, and immediately introduced into a water tank with a water temperature controlled at 25 for cooling and shaping, and then cut into uniform particles of 3 mm by a rotary granulator, and irregular particles are removed through a vibrating screening device;

[0055] S4: The headspace-gas chromatography mass spectrometry method was used for the detection of volatile organic compounds. Exactly 2.000 g of the sample was accurately weighed and placed in a 20 mL headspace vial. After sealing with an aluminum cap and a silicone rubber gasket, it was put into a headspace sampler and equilibrated at a constant temperature of 80 °C for 30 minutes to allow the residual VOCs to fully volatilize into the gas phase space.

[0056] Experimental results: See Table 2 for details.

[0057] Table 2: Test results of Example 2

[0058] Formaldehyde Styrene Phenol Methanol Acetaldehyde Benzene series Hydrogen sulfide Concentration <![CDATA[0.1mg / m 3 > <![CDATA[10mg / m 3 > <![CDATA[0.5mg / m 3 > <![CDATA[8mg / m 3 > <![CDATA[0.5mg / m 3 > <![CDATA[5mg / m 3 > <![CDATA[0mg / m 3 >

[0059] In S1 and S2, due to incomplete devolatilization of monomers, styrene and methanol remained. In the steps of S3, due to the high-temperature decomposition, volatilization of phenolic antioxidants and oxidative degradation under high-temperature environment, phenol, methanol, and acetaldehyde remained in the system. In the raw materials, due to the presence of benzene ring impurities and the volatilization of other benzene-containing structures at high temperature, benzene series substances remained in the system. Among them, the concentrations of all VOCs exceeded the safety standards and could not meet the current requirements for automotive interior products.

[0060] Comparative Example 2

[0061] This example provides a method for preparing thermoplastic elastomer by dynamic vulcanization, which is applicable to various industrial scenarios. The following are the implementation details:

[0062] Experimental purpose:

[0063] Prepare thermoplastic elastomer by dynamic vulcanization.

[0064] Experimental raw materials:

[0065] Polypropylene (PP), ethylene propylene diene monomer (EPDM), dicumyl peroxide (DCP), triallyl isocyanurate (TAIC)

[0066] Experimental steps:

[0067] S1: First, the EPDM raw rubber was put into an open mill for plasticization. By adjusting the roll gap to 1 - 2 mm and controlling the roll temperature at 80 - 100 °C, plasticization was continued for 10 - 15 minutes to reduce the molecular weight and improve the processing fluidity. Subsequently, the plasticized rubber, dicumyl peroxide vulcanizing agent, triallyl isocyanurate co-vulcanizing agent, and silica filler were added to a Banbury mixer according to the ratio, and mixed for 8 - 10 minutes under the conditions of a rotor speed of 40 - 60 r / min and a mixing temperature of 100 - 120 °C to obtain a uniformly dispersed rubber masterbatch. At the same time, the polypropylene thermoplastic resin was placed in a vacuum drying oven and dried at 80 - 120 °C and a vacuum degree of ≤10 kPa for 2 - 4 hours to completely remove the moisture in the raw materials;

[0068] S2: The dried polypropylene and the prepared rubber masterbatch are fed into a twin-screw extruder according to the formula ratio, and the barrel temperature is set at 170-200°C and the screw speed is set at 150-300r / min. The melt blending of the rubber and plastic phases is achieved through the shearing action of the screw to form a uniformly dispersed initial blending system. After the materials are melted, the vulcanizer is quantitatively injected through the side feeding port to induce the in-situ crosslinking reaction of the rubber phase under high temperature and high shear environment. At the same time, the crosslinking rubber phase is broken into fine particles of 1-5μm by the strong shear force of the screw meshing zone. As the vulcanization reaction proceeds, the rubber particles are gradually coated by the polypropylene continuous phase, completing the phase transition from rubber continuous phase-plastic dispersed phase to plastic continuous phase-rubber dispersed phase;

[0069] S3: After the vulcanization reaction is completed, the homogenized melt is extruded through the die hole of the die head into strips with a diameter of 3-5mm, and immediately introduced into a cooling water tank with a water temperature controlled at 25-35℃ for rapid shaping to avoid melt adhesion. The cooled strips are uniformly transported to the rotary pelletizer by a traction machine and cut into uniform particles with a particle size of 3-4mm, thus obtaining finished thermoplastic vulcanized rubber particles.

[0070] Experimental results: See Table 3 for details.

[0071] Table 3: Test results of Example 3

[0072] Formaldehyde Styrene Phenol Methanol Acetaldehyde Benzene series Hydrogen sulfide Concentration <![CDATA[0.09mg / m 3 > <![CDATA[5mg / m 3 > <![CDATA[1mg / m 3 > <![CDATA[2mg / m 3 > <![CDATA[5mg / m 3 > <![CDATA[10mg / m 3 > <![CDATA[0.1mg / m 3 >

[0073] In S1, the system contains styrene impurities due to cyclohexane oil and vulcanization aids, and the cyclohexane oil can only volatilize during the mixing process, resulting in aromatic impurities. In the dynamic vulcanization process in S2, the vulcanizer TAIC will produce a trace of styrene under high temperature conditions, and Irganox 1010 can also decompose and release phenol under high temperature conditions. The added EPDM and PP will oxidize and degrade to generate aldehyde compounds under high temperature. In S3, due to high temperature extrusion, the polymer will further degrade to produce aldehyde and olefin VOCs. The content of various VOCs is slightly higher than the safety standard for daily use.

[0074] The raw materials used in Example 1 are p-tert-butylphenol formaldehyde resin, zinc oxime dimethyldithiocarbamate, and poly(propylene adipate). The content of VOCs is reduced at the raw material level. In the preparation process, the boiling point of the blend is lower than that of the pure substance. When the alcohol substances volatilize, they carry away the remaining VOCs to reduce the VOC concentration in the product. In the raw material mixing stage, the phenolic resin and zinc oxime vulcanizing agent in the system act as a vulcanization system to promote the cross-linking and curing of EPDM to form a network structure, which not only enhances the strength of the system but also blocks sulfur substances and their chemical stability. The use of poly(propylene adipate) replaces the traditional phthalate esters, effectively avoiding the generation of halogenated hydrocarbons caused by thermal decomposition. The 13X type molecular sieve microporous zeolite added in the additives uses its porous structure to adsorb residual VOCs. Through the synergistic action of these mechanisms, the VOCs in the system are greatly reduced.

[0075] Comparing Example 1 with Comparative Example 1, in Example 1, due to the use of a purging device and continuous operation at 70 °C for 2.5 hours, while achieving the effect of volatilizing VOCs, it also promotes their dissipation. In the comparative experiment test results, a large amount of aldehyde substances volatilize under this operation, and only a small amount of aldehyde substances remain in the gaps and are difficult to volatilize. Under this operation, the concentration of benzene substances in the environment is also greatly reduced due to oxidative degradation of benzene series substances. Alcohol substances are difficult to exist in the system at 70 °C because their boiling point is lower than the environmental temperature. Comparing the raw materials in Example 1 with those in Comparative Example 1, substances such as cyclohexane and styrene in Comparative Example 1 are prone to thermal degradation to produce alkane substances and volatile olefin gases during their mixing. Its preparation process does not treat the VOCs in the product, resulting in various VOCs and metastable structures in the system, which will volatilize and thermally decompose in large quantities at environmental temperatures above 60 °C.

[0076] Comparing Example 1 with Comparative Example 2 shows that the ethylene propylene diene monomer (EPDM) and dicumyl peroxide (DCP) introduced in the raw materials exhibit significant thermal instability during the melt blending process. Since the preparation process does not add devolatilization or stabilization treatment steps according to the characteristics of DCP, the content of residual vulcanization active substances in the system is relatively high. When the material is in a high-temperature environment, volatile sulfur compounds such as thiols and thioethers (VOCs) are easily released due to the thermal decomposition reaction of DCP. In addition, the heat resistance performance of the polypropylene (PP) matrix has inherent defects, and its upper limit of long-term use temperature is 130 °C. It is prone to softening and deformation in high-temperature service scenarios. If the application requirements of such scenarios need to be met, the matrix resin needs to be replaced with high-temperature-resistant materials such as nylon (PA), resulting in an increase in raw material costs by more than 50%. On the other hand, excessive filling of silica will cause an increase in the surface roughness of the product. To meet the appearance quality requirements, an additional surface coating process needs to be added, further pushing up the preparation cost.

[0077] Those of ordinary skill in the art can realize that the modules and algorithm steps of each example described in combination with the embodiments disclosed herein can be implemented by electronic hardware, or by a combination of computer software and electronic hardware. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. Professional technicians can use different methods for each specific application to implement the described functions, but such implementation should not be considered to exceed the scope of this application.

[0078] In addition, the functional modules in each embodiment of this application can be integrated into one processing module, or each module can exist physically alone, or two or more modules can be integrated into one module.

[0079] As mentioned above, the above is only the specific implementation manner of this application, but the protection scope of this application is not limited thereto. Any person skilled in the art within the technical scope disclosed in this application can easily think of changes or substitutions, which should all be covered by the protection scope of this application. Therefore, the protection scope of this application should be subject to the protection scope of the claims.

[0080] Finally: The above is only the preferred embodiment of the present invention and is not used to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection of the present invention.

Claims

1. A low-VOCs environmentally friendly PP / EPDM thermoplastic elastomer for automotive interiors, comprising the following weight components: 70 - 80 g of polyphenylene ether, 5 - 8 g of low-density polyvinyl alcohol (molecular weight < 100,000), 30 - 40 g of ethylene propylene diene monomer rubber, 8 - 10 g of p-tert-butylphenolic resin, 0.8 - 1 g of zinc oxime dimethyldithiocarbamate, 5 - 8 g of polypropylene adipate, 3 - 5 g of silane coupling agent KH-560, 2 - 5 g of 13X molecular sieve, and 20 - 25 g of white carbon black.

2. The PP / EPDM thermoplastic elastomer for low-VOC environmentally friendly automotive interiors according to claim 1, characterized in that, The raw materials abandon sulfur and thiazole accelerator systems that are prone to generating sulfur-containing VOCs such as hydrogen sulfide and mercaptans, and instead use a phenolic resin vulcanization system to reduce the sulfur content from the source.

3. The low-VOCs environment-friendly PP / EPDM thermoplastic elastomer for automotive interiors according to claim 2, wherein, The phenolic resin releases water vapor instead of organic volatiles during vulcanization, and the decomposition products of the oxime vulcanizing agent are nitrogen and low-toxicity organic substances.

4. The low-VOCs environment-friendly PP / EPDM thermoplastic elastomer for automotive interiors according to claim 2, wherein The phenolic resin and zinc oxime vulcanizing agent are used as a vulcanization system, which promotes the crosslinking and curing of EPDM to form a network structure, blocks the sulfur-containing substances in the raw materials at the structural level, and simultaneously improves the mechanical properties.

5. The PP / EPDM thermoplastic elastomer for low-VOCs environment-friendly automotive interiors according to claim 1, wherein The high-molecular-weight polyester plasticizer is replaced by polypropylene adipate instead of traditional phthalate esters. Its boiling point is higher than 300 °C and the volatility is reduced by 80%. The organic phosphorus stabilizer triphenyl phosphite is selected to replace the traditional halogen-containing stabilizer to avoid the generation of halogenated hydrocarbon VOCs during thermal decomposition.

6. The low-VOCs environment-friendly PP / EPDM thermoplastic elastomer for automotive interiors according to claim 1, wherein Introducing 5% - 8% of low-molecular-weight polyvinyl alcohol into PP, the hydroxyl groups form hydrogen bond networks with the phenolic resin, further enhancing the stability of the EPDM crosslinked structure, and adsorbing aldehyde and ketone VOCs while improving the strength of the system.

7. The low-VOCs environment-friendly PP / EPDM thermoplastic elastomer for automotive interior as described in claim 1 is characterized in that, The silane coupling agent KH-560 modifies the surface of the filler, enhances the interfacial bonding force between PP / EPDM, reduces the accumulation of VOCs in the phase interface gap, and simultaneously the vacuum devolatilization technology extracts the vulcanization by-products in real time to further reduce the residue.

8. The low-VOCs environment-friendly PP / EPDM thermoplastic elastomer for automotive interiors according to claim 1, wherein Adding 2% - 3% of 13X molecular sieve microporous zeolite with a particle size between 1 - 2 μm to the blending system, and using its porous structure to physically adsorb the residual VOCs.

9. The low-VOCs environment-friendly PP / EPDM thermoplastic elastomer for automotive interiors as claimed in claim 8, wherein The 13X activated molecular sieve is used to adsorb the residual moisture or volatile impurities, improve the purity of the system, and simultaneously play a catalytic role during the vulcanization process.

10. The low-VOCs environmentally friendly PP / EPDM thermoplastic elastomer for automotive interiors according to claim 1, wherein The tensile strength of the thermoplastic elastomer is between 15 - 18 MPa, the elongation at break is greater than 350%, and after aging at 120 °C for 168 h, the tensile strength retention rate is greater than 85%, which is attributed to the thermal stability of the phenolic resin vulcanization network.

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