A low odor low energy impact tpo material and method of making the same

Abstract

The application relates to the technical field of automobile interiors, and particularly discloses a TPO material with low odor and low impact energy and a preparation method thereof. The TPO material with low odor and low impact energy comprises, from bottom to top, a back coating layer, a polypropylene foaming layer, a TPO layer and a surface coating layer; according to mass percentage, the raw materials of the TPO layer comprise 40-55% of EPDM particles, 10-20% of modified TPO particles, 20-30% of polypropylene, 0-5% of an additive and 4-15% of pigments. The TPO material with low odor and low impact energy can be used for preparing a dashboard protective mask of an automobile interior, has the advantages of low impact energy, low odor, aesthetic appearance and comfort, and can meet the burst requirements of different special-structure airbags.

Description

Technical Field

[0001] This application relates to the field of automotive interior technology, and more specifically, to a low-odor, low-impact-energy TPO material and its preparation method. Background Technology

[0002] The continuous improvement of road conditions has greatly increased the speed of automobiles; however, this has also led to a corresponding increase in the incidence of road traffic accidents, posing a serious threat to the safety of drivers and passengers. How to minimize injuries and fatalities to drivers and passengers in the event of a car collision is receiving increasing attention.

[0003] To reduce loss of life and property caused by traffic accidents, automotive airbag systems were developed. When a car is involved in a collision, the airbag can quickly inflate and break through the protective cover on the dashboard, effectively cushioning the impact of the collision and protecting the safety of the occupants.

[0004] Beyond vehicle safety, people are also demanding higher standards for the aesthetics and comfort of car interiors. In recent years, integrated airbag dashboards have gained popularity due to their beauty and practicality. This design involves laser-weakening the dashboard protective cover and machining micro-holes on its inner side to create weakening lines for the airbag, thereby reducing the strength of the corresponding area of ​​the dashboard protective cover and ensuring that the airbag can deploy properly in the event of a collision.

[0005] Although the design of the integrated airbag dashboard protector meets people's dual needs for vehicle safety and aesthetics to a certain extent, the weakening process of traditional automotive interior dashboard protectors is relatively complex, and the final product may have slight defects in appearance.

[0006] Currently, there are instrument panel materials available on the market that eliminate the need for laser weakening of instrument panel protective covers, thus improving production efficiency. However, the inventors have found that these non-weakening instrument panel protective covers generally have higher impact energy. While they can meet the bursting requirements of conventional airbags, they are difficult to achieve direct bursting when applied to airbags with special structures (such as U-shaped airbags), and they also produce a stronger odor than laser-weakened products. Summary of the Invention

[0007] In order to reduce the impact energy of dashboard materials and reduce odor, while ensuring vehicle safety and taking into account the aesthetics, comfort and ease of processing of the vehicle interior, this application provides a low-odor, low-impact-energy TPO material and its preparation method.

[0008] In a first aspect, this application provides a low-odor, low-impact-energy TPO material, which adopts the following technical solution: a low-odor, low-impact-energy TPO material, comprising, from bottom to top, a back coating layer, a polypropylene foam layer, a TPO layer and a surface coating layer;

[0009] The raw materials of the TPO layer, by weight percentage, include 40-55% EPDM particles, 10-20% modified TPO particles, 20-30% polypropylene, 0-5% additives, and 4-15% pigments.

[0010] Optionally, the additive is a hindered amine light stabilizer.

[0011] By adopting the above technical solution, EPDM granules are a rubber material composed of ethylene, propylene, and a small amount of diene monomers (such as ENB or DCPD). The diene monomers provide the cross-linking structure of EPDM, giving it good flexibility and toughness, and enabling it to quickly recover its original shape under external force. EPDM has good compatibility with raw materials such as TPO and polypropylene. Using EPDM granules as a matrix to prepare a TPO layer can form a ternary composite material that combines the flexibility and resilience of rubber with the ease of plastic processing. This composite material can better adapt to the deformation caused by impact, better absorb and disperse impact energy, thereby effectively reducing impact energy and making the car dashboard more likely to rupture under burst impact, facilitating the deployment of airbags.

[0012] In addition, the inventors also discovered that EPDM particles have excellent resistance to temperature changes and chemical stability, and can maintain excellent flexibility at low temperatures. This helps to improve the low-temperature environmental adaptability of composite materials, so that they can maintain material performance and low impact energy under different climate and environmental conditions. When applied to the preparation of automotive dashboard protective covers, it can ensure the timely deployment of airbags even in extreme winter temperatures, thereby improving the safety performance of automobiles.

[0013] Optionally, the polypropylene is modified polypropylene, and the raw materials of the modified polypropylene include 20-30 parts polypropylene, 0.1-0.2 parts dicumyl peroxide and 2-5 parts dihydroxy flexible segment compound by weight.

[0014] Optionally, the dihydroxy flexible segment compound is selected from any one or a combination of two of polyethylene glycol or polypropylene glycol.

[0015] Optionally, the method for preparing the modified polypropylene includes the following steps:

[0016] According to the proportions of each raw material, weigh out polypropylene, dicumyl peroxide and dihydroxy flexible segment compound, mix them, melt-blend them through screw extrusion, and then extrude and granulate them to obtain the final product.

[0017] The extrusion temperature is 180-200℃, and the screw speed is 100-150 r / min.

[0018] By adopting the above technical solution, the inventors discovered that since polypropylene is a partially crystalline polymer, its impact performance is poorly affected by crystallinity and spherulite structure. By introducing dihydroxy flexible segments into polypropylene through melt grafting, the flexibility of polypropylene itself can be significantly improved.

[0019] Both polyethylene glycol and polypropylene glycol are linear dihydroxy compounds with flexible long chains, which can be easily introduced into the polypropylene macromolecular chain through melt grafting. This helps to improve the flexibility of polypropylene, enabling it to absorb more energy when subjected to impact, thereby reducing the impact energy.

[0020] In addition, both polyethylene glycol and polypropylene glycol have multiple hydroxyl groups. These polar groups can interact with the polar groups in EPDM and TPO to form an interpenetrating network structure, reducing stress concentration at the interface and phase separation in the composite material. This helps to reduce the transmission and accumulation of impact energy inside the material, allowing the composite material to better absorb and disperse energy when impacted, further reducing the impact energy of the composite material. This makes the car dashboard more likely to rupture under explosive impact, ensuring the timely deployment of airbags.

[0021] Optionally, the preparation method of the modified TPO particles includes the following steps:

[0022] TPO particles, nano-silica, and embrittlement agent are mixed evenly, and then dimethyl sulfoxide is added and mixed further. After melt extrusion and granulation, the mixture is irradiated with an electron beam at an intensity of 3050 kGy to obtain the final product. The mass ratio of TPO particles, nano-silica, and embrittlement agent is (100-120):(3-5):(7-10). The embrittlement agent includes polylactic acid and hyperbranched polyamide ester in a mass ratio of 1:(3-6).

[0023] By adopting the above technical solution, polylactic acid in the embrittlement agent can be uniformly dispersed in the polymer resin system formed by the melt blending of EPDM particles, modified TPO particles and polypropylene, and form multiple embrittlement points. The hyperbranched polyamide ester in the embrittlement agent has a large number of active groups, such as hydroxyl and carbonyl groups, which can interact with polylactic acid through the formation of hydrogen bonds and cross-linking, forming a strength and toughness gradient from the embrittlement point outward. It has low burst strength and tear strength, which makes the car dashboard have good tensile strength and is more likely to break under burst impact. There is no need for laser weakening or other processes during processing, resulting in lower cost and higher processing efficiency.

[0024] After electron beam irradiation, the molecular structure of the modified TPO particles is impacted by the electron beam, activating more embrittlement points. At the same time, the strength and toughness gradient centered on the embrittlement points becomes more uniform, allowing them to break in time under certain explosive impacts without the need for laser weakening or other processes, resulting in better safety.

[0025] Optionally, the raw materials for the surface treatment layer include modified acrylic resin and additives;

[0026] The modified acrylic resin comprises, by weight percentage, 30-40% glossy resin and 60-70% semi-gloss resin.

[0027] Based on the total mass of the modified acrylic resin, the additives include 3-5% fragrance, 0-10% hand feel agent, 2-8% crosslinking agent and 0-50% water.

[0028] Optionally, the fragrance agent is a pine-based fragrance emulsion.

[0029] Optionally, the feel-enhancing agent is an organosilicon material.

[0030] Optionally, the crosslinking agent is selected from any one or more combinations of polycarbodiimide crosslinking agents, aziridine crosslinking agents, and oxazoline crosslinking agents.

[0031] By adopting the above technical solution, the pine-based fragrance emulsion possesses a unique pine aroma. This aroma can mask any potential odors present in the TPO material itself, enhancing the overall pleasantness of the TPO material's scent. Furthermore, the fragrance molecules in the pine-based fragrance emulsion can adhere to the surface of the TPO material through physical adsorption. This adsorption not only strengthens the bond between the fragrance and the TPO material but also helps reduce the release of the TPO material's own odor, thereby lowering the odor level of the TPO material.

[0032] Optionally, the raw material for the back coating is water-based polyurethane resin or polyolefin resin.

[0033] By adopting the above technical solution, waterborne polyurethane resin or polyolefin resin as the back coating material helps to change the surface polarity of TPO material, thereby improving the adhesion between TPO material and the coated template.

[0034] Secondly, this application provides a method for preparing a low-odor, low-impact-energy TPO material, employing the following technical solution:

[0035] A method for preparing a low-odor, low-impact-energy TPO material includes the following steps:

[0036] S1: Weigh the raw materials for the TPO layer according to the formula, mix them, melt extrude and injection mold them to form the TPO layer, and thermally composite the polypropylene foam with one side of the TPO layer to form a polypropylene foam layer, thus obtaining the TPO substrate.

[0037] S2: Weigh the raw materials for the surface coating according to the formula, mix them, coat them on the surface of the TPO substrate, and dry them to form a surface treatment layer to obtain the pre-made TPO material;

[0038] S3: The raw material for coating the back coating layer on one side of the polypropylene foam layer in the pre-made TPO material is dried to form the back coating layer, thus obtaining a TPO material with the following layers from bottom to top: back coating layer, polypropylene foam layer, TPO layer and surface coating layer.

[0039] By adopting the above technical solution, TPO materials with low impact energy can be obtained without laser weakening processing, while significantly reducing the odor of the TPO material. When used to cover automotive dashboards to form protective covers, it is less prone to rupture under burst impact, reducing the drag when the airbag deploys, thus ensuring the timely deployment of the airbag. This meets the deployment requirements of airbags with different special structures, simplifies the processing process, and improves processing efficiency.

[0040] In summary, this application has the following beneficial effects:

[0041] 1. Since this application uses EPDM particles as the matrix and combines them with modified TPO particles and polypropylene to form a ternary composite system, it effectively combines the excellent flexibility and resilience of rubber with the processing convenience of plastics. This allows the composite material to better adapt to the deformation caused by impact and explosion, absorb and disperse impact energy, making the car dashboard more likely to break under the impact of explosion. It also effectively reduces the resistance of the airbag when it is deployed, ensuring the safety of the car while taking into account the aesthetics, comfort and processing convenience of the car interior.

[0042] 2. In this application, the modified polypropylene formed by grafting with dihydroxy flexible segment compounds is preferred, which helps to improve the flexibility of polypropylene, enhance the phase uniformity and stability of the TPO layer, and promote the absorption of more energy by the TPO material when it is subjected to impact, thereby further reducing the impact energy of the TPO material.

[0043] 3. The method of this application can obtain TPO material with low impact energy without laser weakening process, which significantly reduces the odor of the product TPO material and makes it easy to break under burst impact, thereby ensuring the timely deployment of airbags and meeting the burst requirements of airbags with different special structures. Detailed Implementation

[0044] The following embodiments provide a further detailed description of this application.

[0045] raw material

[0046] Unless otherwise specified, the raw materials used in the embodiments and comparative examples in this application are all commercially available products, specifically: EPDM particles, selected from Exxon, EPDM5601;

[0047] Polypropylene, selected from Basel PP KY6110;

[0048] Polyethylene glycol, HO(CH2CH2O)nH, has an average molecular weight of 2000;

[0049] Polypropylene glycol, HO(C3H6O)nH, has an average molecular weight of 2000.

[0050] The additive is a hindered amine light stabilizer, selected from Beijing Tiangang Additives, light stabilizer 622;

[0051] The pigment is carbon black, selected from Shenhong Pigment, iron oxide black 790;

[0052] TPO particles, selected from TeknorApex, TL-2468A;

[0053] Nano-silica, which is spherical nano-silica with an average particle size of 100nm;

[0054] Polylactic acid, selected from Zhejiang Hisun Biomaterials Co., Ltd., REVODE101;

[0055] Hyperbranched polyamide ester, synthesized from dodecenyl succinic anhydride and diisopropanolamine, is selected from Shanghai Xibao Biotechnology Co., Ltd., Hybrane D 2800;

[0056] Glossy resin, selected from LX MMA, BA124;

[0057] Semi-bright resin, selected from Shanghai Kaiyin Chemical Co., Ltd., TK1209;

[0058] The fragrance agent is a pine-type fragrance emulsion, selected from the pine fragrance emulsion of Shandong Quanjin Fine Chemical Co., Ltd.

[0059] The feel-enhancing agent is an organosilicon material selected from Dow Corning, DC-51;

[0060] The crosslinking agent is a aziridine crosslinking agent, selected from... Waterborne polyurethane resin with a solid content of 30% was selected from Hefei Huayue New Material Technology Co., Ltd., 8001Y.

[0061] Examples of preparation of modified TPO particles: 1.1-1.4

[0062] Preparation Example 1.1

[0063] The preparation method of modified TPO particles includes the following steps:

[0064] S1: Mix 100Kg of TPO granules, 3Kg of nano silica and 7Kg of embrittlement agent evenly, then add to an extruder, add 0.2Kg of dimethyl sulfoxide, and after melt blending extrusion and granulation, obtain pretreated TPO granules. The embrittlement agent is polylactic acid and hyperbranched polyamide ester in a mass ratio of 1:3.

[0065] S2: The pretreated TPO particles are irradiated with an electron beam of 40 kGy intensity for 15 min to obtain the final product.

[0066] Preparation Example 1.2

[0067] The preparation method of modified TPO particles includes the following steps:

[0068] S1: Mix 107 kg of TPO granules, 4 kg of nano-silica and 8 kg of embrittlement agent evenly, then add them to an extruder, add 0.55 kg of dimethyl sulfoxide, and after melt blending extrusion and granulation, obtain pretreated TPO granules. The embrittlement agent is polylactic acid and hyperbranched polyamide ester in a mass ratio of 1:4.

[0069] S2: The pretreated TPO particles are irradiated with an electron beam of 30 kGy intensity for 15 min to obtain the final product.

[0070] Preparation Example 1.3

[0071] The preparation method of modified TPO particles includes the following steps:

[0072] S1: Mix 113Kg of TPO granules, 4.5Kg of nano silica and 9Kg of embrittlement agent evenly, then add them to an extruder, add 1Kg of dimethyl sulfoxide, and after melt blending extrusion and granulation, obtain pretreated TPO granules. The embrittlement agent is polylactic acid and hyperbranched polyamide ester with a mass ratio of 1:5.

[0073] S2: The pretreated TPO particles are irradiated with an electron beam of 40 kGy intensity for 15 min to obtain the final product.

[0074] Preparation Example 1.4

[0075] The preparation method of modified TPO particles includes the following steps:

[0076] S1: Mix 120Kg of TPO granules, 5Kg of nano silica and 10Kg of embrittlement agent evenly, then add them to an extruder, add 1.2Kg of dimethyl sulfoxide, and after melt blending extrusion and granulation, obtain pretreated TPO granules. The embrittlement agent is polylactic acid and hyperbranched polyamide ester in a mass ratio of 1:6.

[0077] S2: The pretreated TPO particles are irradiated with an electron beam of 50 kGy intensity for 15 min to obtain the final product.

[0078] Examples of modified polypropylene preparation: 2.1-2.3

[0079] Preparation Example 2.1

[0080] Modified polypropylene, the preparation method of which includes the following steps:

[0081] According to the proportions of each raw material, weigh 20 kg of polypropylene, 0.1 kg of dicumyl peroxide and 2 kg of dihydroxy flexible segment compound, mix them evenly and add them to the extruder. Set the extrusion temperature to 180-200℃ and the screw speed to 100 r / min. After melt blending through screw extrusion, extrude and granulate to obtain the final product.

[0082] Among them, the dihydroxy flexible segment compound is polyethylene glycol.

[0083] Preparation Example 2.2

[0084] Modified polypropylene, the preparation method of which includes the following steps:

[0085] According to the proportions of each raw material, weigh 25 kg of polypropylene, 0.15 kg of dicumyl peroxide and 3.5 kg of dihydroxy flexible segment compound, mix them evenly and add them to the extruder. Set the extrusion temperature to 180-200℃ and the screw speed to 150 r / min. After the melt blend is extruded through the screw, it is extruded and granulated to obtain the final product.

[0086] Among them, the dihydroxy flexible segment compound is polypropylene glycol.

[0087] Preparation Example 2.3

[0088] Modified polypropylene, its preparation method includes the following steps:

[0089] According to the proportions of each raw material, weigh 30 kg of polypropylene, 0.2 kg of dicumyl peroxide and 5 kg of dihydroxy flexible segment compound, mix them evenly and add them to the extruder. Set the extrusion temperature to 180-200℃ and the screw speed to 120 r / min. After the melt blend is extruded through the screw, it is extruded and granulated to obtain the final product.

[0090] Among them, the dihydroxy flexible segment compound is polyethylene glycol and polypropylene glycol in a mass ratio of 1:1.

[0091] Example

[0092] Example 1

[0093] A low-odor, low-impact-energy TPO material, comprising, from bottom to top, a back coating layer, a polypropylene foam layer, a TPO layer, and a surface coating layer;

[0094] The raw material composition and dosage of the TPO layer are shown in Table 1. Among them, the polypropylene is modified polypropylene, which was prepared by Preparation Example 2.1. The raw materials of the surface coating include modified acrylic resin and additives. The dosage of the additives is expressed based on the total mass of the modified acrylic resin. The raw materials and dosages are shown in Table 2. Among them, the fragrance is pine-type fragrance emulsion, the hand feel aid is an organosilicon material, and the crosslinking agent is aziridine crosslinking agent.

[0095] The raw material for the back coating is water-based polyurethane resin.

[0096] Table 1

[0097]

[0098] Table 2

[0099]

[0100]

[0101] The preparation method of the above-mentioned low-odor, low-impact-energy TPO material includes the following steps:

[0102] S1: Weigh the raw materials for the TPO layer according to the formula, mix them and add them to the extruder for melt blending and extrusion at an extrusion temperature of 200℃. Then, injection mold to form the TPO layer. Heat-composite a 2.5mm thick polypropylene foam to one side of the TPO layer to form a polypropylene foam layer, thus obtaining the TPO substrate.

[0103] S2: Weigh the raw materials for the surface coating according to the formula, mix them, coat them on the surface of the TPO substrate, and dry them to form a surface treatment layer to obtain the pre-made TPO material;

[0104] S3: The raw material for coating the back coating layer on one side of the polypropylene foam layer in the pre-made TPO material is dried to form the back coating layer, thus obtaining a TPO material with the following layers from bottom to top: back coating layer, polypropylene foam layer, TPO layer and surface coating layer.

[0105] Example 2

[0106] A low-odor, low-impact-energy TPO material differs from Example 1 in that the raw materials and amounts of the TPO layer and the surface coating are shown in Tables 1 and 2, while the other steps are the same as in Example 1.

[0107] Example 3

[0108] A low-odor, low-impact-energy TPO material differs from Example 1 in that the raw materials and amounts of the TPO layer and the surface coating are shown in Tables 1 and 2, while the other steps are the same as in Example 1.

[0109] Example 4

[0110] A low-odor, low-impact-energy TPO material differs from Example 1 in that the raw materials and amounts of the TPO layer and the surface coating are shown in Tables 1 and 2, while the other steps are the same as in Example 1.

[0111] Example 5

[0112] A low-odor, low-impact-energy TPO material, which differs from Example 1 in that the polypropylene in the TPO layer raw material is modified polypropylene, prepared by Preparation Example 2.2, while the other steps are the same as in Example 1.

[0113] Example 6

[0114] A low-odor, low-impact-energy TPO material, which differs from Example 1 in that the polypropylene in the TPO layer raw material is modified polypropylene, prepared by Preparation Example 2.3, while the other steps are the same as in Example 1.

[0115] Example 7

[0116] A low-odor, low-impact-energy TPO material, differing from Example 1 in that the polypropylene in the TPO layer raw material is not modified and is Basel PP KY6110, while the other steps are the same as in Example 1.

[0117] Example 8

[0118] A low-odor, low-impact-energy TPO material, which differs from Example 1 in that no fragrance is added to the surface coating, while all other steps are the same as in Example 1.

[0119] Example 9

[0120] A low-odor, low-impact-energy TPO material differs from Example 1 in that, based on the total mass of the modified acrylic resin, the amount of fragrance added to the surface coating is 2%, while all other steps are the same as in Example 1.

[0121] Example 10

[0122] A low-odor, low-impact-energy TPO material differs from Example 1 in that, based on the total mass of the modified acrylic resin, the amount of fragrance added to the surface coating is 3%, while all other steps are the same as in Example 1.

[0123] Example 11

[0124] A low-odor, low-impact-energy TPO material differs from Example 1 in that, based on the total mass of the modified acrylic resin, the amount of fragrance added to the surface coating is 5%, while all other steps are the same as in Example 1.

[0125] Example 12

[0126] A low-odor, low-impact-energy TPO material differs from Example 1 in that, based on the total mass of the modified acrylic resin, the amount of fragrance added to the surface coating is 6%, while all other steps are the same as in Example 1.

[0127] Comparative Example

[0128] Comparative Example 1

[0129] A low-odor, low-impact-energy TPO material, differing from Example 1 in that no polypropylene is added, and the polypropylene in the raw materials is replaced with an equal mass of modified TPO particles. The modified TPO particles are prepared according to Preparation Example 1.1, and all other steps are the same as in Example 1.

[0130] Comparative Example 2

[0131] A low-odor, low-impact-energy TPO material differs from Example 1 in that the amount of polypropylene is 15% and the amount of EPDM particles is 60%, while the other steps are the same as in Example 1.

[0132] Comparative Example 3

[0133] A low-odor, low-impact-energy TPO material differs from Example 1 in that the amount of polypropylene is 35% and the amount of EPDM particles is 40%, while the other steps are the same as in Example 1.

[0134] Comparative Example 4

[0135] A low-odor, low-impact-energy TPO material, which differs from Example 1 in that no EPDM particles are added, and the EPDM particles in the raw materials are replaced with an equal mass of modified TPO particles. The modified TPO particles are prepared by Preparation Example 1.1, and all other steps are the same as in Example 1.

[0136] Performance testing

[0137] The following performance tests were conducted on the low-odor, low-impact-energy TPO materials obtained in Examples 1-12 and Comparative Examples 1-4. Each test was performed three times, and the average value of the three tests was taken as the final result. The final results are recorded in Tables 3 and 4.

[0138] 1. Impact Energy: Refer to the relevant standards and regulations of GB / T1843-2008 "Determination of Impact Performance of Plastic Cantilever Beams" to test the impact energy. When the impact energy is ≤10J, the TPO material meets the burst requirements of airbags with different special structures.

[0139] 2. Tensile strength: Refer to the relevant standards and regulations of GB / T 1040-92 "Test Method for Tensile Properties of Plastics" to test the tensile strength. When the tensile strength is ≥1.3MPa, it meets the requirements for use in automotive interiors.

[0140] 3. Tear strength: Tear strength shall be tested in accordance with the relevant standards and regulations of ISO-37 "Determination of tear strength".

[0141] 4. Burst Test: Refer to the relevant standards and regulations of QLQBC-235-2014 "Instrument Panel Test Method" to conduct burst tests. After storing each group of TPO materials at -35±2℃, 23±4℃ and 85±2℃ for 6 hours, static burst tests are carried out to observe the airbag bursting.

[0142] 5. Odor Test: Odor test shall be conducted in accordance with the relevant standards and regulations of PV3900 "Odor Test of Components in the Interior of Automobile Cabin". Odor ratings of 2.5-3.0 shall be designated as A, 3.0-3.5 as B, and ≥3.5 as C. An odor rating of ≤3.5 shall meet the requirements for use of automobile interior.

[0143] Table 3

[0144]

[0145] Table 4

[0146]

[0147] According to the performance test results in Table 3-4, the TPO materials prepared by the method of this application all have impact energy <10J, tensile strength >1.3MPa, tear strength range of 8.56-11.41N / mm, and odor rating of A. This indicates that the TPO materials prepared by the method of this application have the characteristics of low odor and low impact energy. When applied to some special structure airbags (such as U-shaped airbags), they are easy to achieve direct bursting. The performance of TPO materials can still be guaranteed at low temperatures. While ensuring the safety of automobiles, it can also take into account the aesthetics, comfort and processing convenience of automobile interiors.

[0148] According to the performance test results of Examples 1-7, Comparative Examples 1 and 4, it can be seen that using EPDM particles as the matrix, combined with modified TPO particles and polypropylene to form a ternary composite system, effectively combines the excellent flexibility and resilience of EPDM rubber with the processing convenience of plastics. The composite material can adapt to the deformation caused by impact and explosion, and absorb and disperse impact energy in a timely manner.

[0149] After grafting modification of polypropylene, flexible segments of dihydroxy flexible segment compounds are introduced into polypropylene, which significantly improves the flexibility of polypropylene itself and enhances the phase uniformity and stability of the TPO layer. This allows the TPO composite material to absorb more energy when subjected to impact, further reducing the impact energy of the material. This ensures that the specially structured car dashboard is easy to rupture under burst impact, prompting the airbag to deploy in time and play an effective role.

[0150] According to the performance test results of Examples 1-7 and Comparative Examples 2-3, when the amount of modified polypropylene added is 20-30%, the TPO material can have lower impact energy while ensuring the original processing and molding performance, so that it can be matched with a wider range of airbags.

[0151] According to the performance test results of Examples 1-4 and Examples 8-12, it can be seen that when the amount of fragrance added is 3-5%, the TPO material can have a lower odor and better odor performance while ensuring the original surface properties.

[0152] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A low-odor, low-impact-energy TPO material, characterized in that, From bottom to top, it includes a back coating layer, a polypropylene foam layer, a TPO layer, and a surface coating layer; By mass percentage, the raw materials of the TPO layer include 40-55% EPDM particles, 10-20% modified TPO particles, 20-30% modified polypropylene, 0-5% additives, and 4-15% pigments; by weight, the raw materials of the modified polypropylene include 20-30 parts polypropylene, 0.1-0.2 parts dicumyl peroxide, and 2-5 parts dihydroxy flexible segment compound; the dihydroxy flexible segment compound is selected from any one or a combination of two of polyethylene glycol or polypropylene glycol. The method for preparing the modified polypropylene includes the following steps: According to the proportions of each raw material, weigh out polypropylene, dicumyl peroxide and dihydroxy flexible segment compound, mix them, melt-blend them through screw extrusion, and then extrude and granulate them to obtain the final product. The extrusion temperature is 180-200℃, and the screw speed is 100-150 r / min; The method for preparing the modified TPO particles includes the following steps: TPO particles, nano-silica, and embrittlement agent are mixed evenly, and then dimethyl sulfoxide is added and mixed further. After melt extrusion and granulation, the mixture is irradiated with an electron beam at an intensity of 30-50 kGy to obtain the final product. The mass ratio of TPO particles, nano-silica, and embrittlement agent is (100-120):(3-5):(7-10). The embrittlement agent includes polylactic acid and hyperbranched polyamide ester in a mass ratio of 1:(3-6).

2. The low-odor, low-impact-energy TPO material according to claim 1, characterized in that, The raw materials for the surface coating include modified acrylic resin and additives; The modified acrylic resin comprises 30-40% glossy resin and 60-70% semi-gloss resin by weight percentage. Based on the total mass of the modified acrylic resin, the additives include 3-5% fragrance, 0-10% hand feel additive, 2-8% crosslinking agent and 0-50% water.

3. The low-odor, low-impact-energy TPO material according to claim 2, characterized in that, The fragrance agent is a pine-type fragrance emulsion.

4. A method for preparing a low-odor, low-impact-energy TPO material according to any one of claims 1-3, characterized in that, Includes the following steps: S1: Weigh the raw materials for the TPO layer according to the formula, mix them, melt extrude and injection mold them to form the TPO layer, and thermally composite the polypropylene foam with one side of the TPO layer to form a polypropylene foam layer, thus obtaining the TPO substrate. S2: Weigh the raw materials for the surface coating according to the formula, mix them, coat them on the surface of the TPO substrate, and dry them to form a surface treatment layer to obtain the pre-made TPO material; S3: The raw material for coating the back coating layer on one side of the polypropylene foam layer in the pre-made TPO material is dried to form the back coating layer, thus obtaining a TPO material with the following layers from bottom to top: back coating layer, polypropylene foam layer, TPO layer and surface coating layer.

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