Electrically conductive heating tpe material and its use as a car part

Abstract

The application discloses a conductive heating TPE material and application thereof as automobile parts. The existing TPE for automobiles is not conductive, and is limited in application, and is not easy to heat, and further has a TPE compression problem; the application mainly adopts the following technical points: developing a modified material, improving the cold resistance of the material, realizing the conductivity of the material, and improving the hardness and compression of the material. The conductive heating TPE material is prepared by blending a conductive modifier, a random copolymer polypropylene resin material, SEBS rubber, paraffin oil, a processing aid and a colorant, and is used in the field of automobile parts and parts prone to icing in winter.

Description

Technical Field

[0001] This invention pertains to polypropylene modification technology and relates to a modified polypropylene material, specifically the development of a conductive heating TPE material and its application as an automotive part. Background Technology

[0002] Thermoplastic elastomers (TPEs), which are elastic like rubber at room temperature and can be melted and processed like plastics at high temperatures, have become one of the key materials in the automotive industry due to their excellent elasticity, durability, environmental friendliness, and recyclability. TPE materials are widely used in many automotive components, from sealing strips and trim parts to interior and exterior trim parts. TPE's unique advantages have changed the way traditional automotive materials are used. Currently, in winter, when cars freeze, ice can form on fuel filler caps or charging port caps, making it impossible to open them for charging or refueling. This requires pouring hot water to thaw or using a shovel to remove the ice, a process that can damage the car's paint.

[0003] Existing technology provides an NTC heating wire, in which the heating core layer is a metal resistance wire spirally wound on the outer surface of the central tensile core; both the main sensing layer and the sentinel sensing layer contain a thermoplastic elastomer matrix and conductive fillers dispersed therein, the conductive fillers being thermosensitive organic-inorganic composite powders. Existing technology discloses a flexible heating film, in which granules obtained by extruding a mixture of thermoplastic elastomer and conductive material are used as the material for preparing the conductive layer; the conductive material includes one or more combinations of carbon nanotubes, graphene, or conductive carbon black. Existing technology discloses a flexible low-voltage composite polymer heating film, in which a plasticized thermoplastic elastomer, half of a uniformly mixed solid powder, a high-flow agent, and an antioxidant are added to a mixer and mixed uniformly; then the other half of the uniformly mixed solid powder and base oil are added and mixed again; the solid powder includes conductive carbon black, graphene, and natural graphite; the mixed material is pulverized and extruded in an extruder; the extruded material is then fed into a four-roll calender to press out a composite film.

[0004] While existing literature presents technical solutions for mixing conductive materials with elastomers, these solutions have drawbacks for automotive applications, such as poor cold resistance, aesthetic defects, and weak heating capabilities. Therefore, a new formulation is needed, based on TPE elastomers, with carefully designed and appropriately added raw materials to achieve conductive and heating functions, as well as cold resistance and a satisfactory appearance. Summary of the Invention

[0005] Existing automotive TPEs are non-conductive, limiting their applications, and are difficult to heat, also exhibiting compressive strength issues. This invention addresses these shortcomings by employing the following key technical points: developing modified materials to improve cold resistance, achieve conductivity, and enhance hardness and compressive strength. Specifically, a conductive and heat-generating TPE material is prepared by blending conductive modifiers, random copolymer polypropylene resin, SEBS rubber, paraffin oil, processing aids, and colorants, for use in automotive components frequently used in winter and prone to icing.

[0006] The present invention adopts the following technical solution.

[0007] A conductive heating TPE material, with the following formulation by weight percentage: Polypropylene 12%-20% SEBS 30%-40% Paraffin oil 30%-40% Carbon nanotubes 10%-25% Conductive ionic liquids 1%-5% Conductive polyether block compounds 1%-10% Other processing aids: 1%-3%.

[0008] Existing technologies achieve good conductivity by using compounded conductive agents, typically using different carbon materials. This invention does not follow the conventional approach, but creatively combines carbon nanotubes with conductive ionic liquids and conductive polyether blocks to achieve excellent conductivity of less than 100Ω or even less than 50Ω. Moreover, it is better than using carbon black or carbon powder. The main advantage is that the disclosed conductive heating TPE material is suitable for automotive exterior parts applications, has a satisfactory appearance, and exceeds people's expectations.

[0009] Preferably, the above-mentioned conductive heating TPE material has the following composition by weight percentage: Polypropylene 12%-17% SEBS 30%-36% Paraffin oil 30%-37% Carbon nanotubes 10%-16% Conductive ionic liquids 2%-5% Conductive polyether block copolymers 2%-8% Other processing aids: 1%-3%.

[0010] Preferably, the above-mentioned conductive heating TPE material has the following composition by weight percentage: Polypropylene 13%-15% SEBS 30%-35% Paraffin oil 30%-35% Carbon nanotubes 10%-15% Conductive ionic liquids 3%-5% Conductive polyether block copolymers 3%-7% Other processing aids: 1%-3%.

[0011] This invention discloses a method for preparing the aforementioned conductive heating TPE material, comprising the following steps: melting and mixing the formulation components to obtain the aforementioned conductive heating TPE material. Specifically, using conventional technology, as an example, after mixing, the materials used in this invention are fed into a twin-screw extruder for melt processing. The speed can be 200-650 RPM, and the temperature can be 130-220℃ for processing and granulation.

[0012] In this invention, the conductive ionic liquid is 1-ethyl-3-methylimidazolium difluorosulfonylimide salt. The conductive polyether block compound is a polyether block amide.

[0013] This invention discloses the application of the above-mentioned conductive heating TPE material in the preparation or as a conductive heating product.

[0014] This invention discloses the application of the above-mentioned conductive heating TPE material in the preparation or as a conductive heating elastic product.

[0015] This invention discloses the application of the above-mentioned conductive heating TPE material in the preparation or as a conductive heating automotive product.

[0016] This invention discloses the application of the above-mentioned conductive heating TPE material in the preparation of or as a conductive heating automotive exterior product.

[0017] This invention discloses the application of the above-mentioned conductive heating TPE material in the preparation of or as a conductive heating automotive exterior part.

[0018] An automotive product, the raw materials for which it is prepared include the aforementioned conductive heating TPE material.

[0019] Preferably, the automotive product is an external part of an automobile.

[0020] In automotive parts manufacturing, TPE (thermoplastic elastomers) are a preferred choice due to their unique material properties. These materials combine the elasticity of rubber with the processing performance of plastics. They can be repeatedly melted and processed within a molding temperature range of 200-265℃, and are efficiently molded through injection molding or extrusion processes, making them particularly suitable for components that require repeated contact or exposure to mechanical stress. TPE parts need to balance comfort and durability, often using materials with a Shore hardness of 70A-75A. Compared to traditional rubber, the vulcanization-free nature of TPEs reduces energy consumption and waste during production, aligning with the automotive industry's trend towards lightweighting and environmental protection. Current technologies achieve a resistivity of around 1000 Ω for conductive TPEs by adding carbon black, metal fibers, or metal oxides. However, as external parts in automobiles primarily used for static dissipation, electromagnetic shielding, and dust prevention, existing products struggle to meet aesthetic requirements and achieve heating capabilities in extremely cold environments. These are technical challenges that current products need to address. This invention employs a novel formulation, using conventional random copolymer polypropylene resin, SEBS rubber, and paraffin oil as a base, supplemented with conductive modifiers, processing aids, and colorants to prepare a conductive heating TPE material. A resistance meter test of a 120mm×120mm×2mm sheet at both diagonal ends showed a resistance (Ω) of less than 100; hardness (A) was 70-75; tensile strength (MPa) was greater than 5.5; importantly, it exhibited excellent heating rate (S), reaching 80℃ from room temperature in less than 30 seconds at a constant voltage of 12V. For automotive exterior parts, this invention offers a superior appearance; injection-molded 12×12×2mm square sheets show no aggregation on the conductive heating TPE surface (i.e., a satisfactory appearance). It can be used in automotive parts frequently used in winter and in areas prone to icing. Attached Figure Description

[0021] Figure 1 This is a photograph of the injection molded part of the product in Embodiment 5 of the present invention.

[0022] Figure 2 This is a large-format photograph of the product from Embodiment 5 of the present invention.

[0023] Figure 3 Large-format photos of our existing products. Detailed Implementation

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. Unless otherwise specified, percentages in this application refer to percentages by mass.

[0025] Conductive TPE materials can be used to manufacture automotive parts to provide excellent antistatic properties. Currently, conductive carbon black is often used as an additive; however, conductive carbon black can degrade some physical properties of the material, and existing technologies do not offer TPEs that simultaneously possess good heating performance and low electrical resistance. For specific applications, such as fuel tank caps as automotive exterior parts, this invention employs a novel technical approach. Based on polypropylene, SEBS, and filler oil, it creatively combines carbon nanotubes with conductive ionic liquids and conductive polyether blocks to achieve excellent conductivity of less than 100Ω, even less than 50Ω, surpassing the performance of carbon black and carbon powder. Combined with conventional additives, the resulting TPE exhibits good conductivity and heating performance while maintaining good physical and mechanical properties, especially a good appearance, making it suitable as a material for automotive exterior parts. This meets the performance requirements of development and design, and addresses the issue of parts freezing in winter.

[0026] The thermoplastic elastomer matrix is ​​a polypropylene, SEBS, and filler oil system, which has good elasticity, wear resistance, and processability, making it suitable for use as automotive exterior parts. The use of a compounded conductive agent combined with additives creates a good conductive network within the elastomer, reducing the risk of material embrittlement caused by conductive modification and ensuring the performance of the elastic component. Furthermore, this invention features integrated fabrication, a simple process flow, high production efficiency, ease of large-scale production, and stable performance.

[0027] To facilitate understanding of this application, a more comprehensive description will be provided below. This application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application. The technical advancements of this invention are illustrated below through experiments. The raw materials used are existing products that meet the requirements for automotive component materials, and the specific preparation operations and performance tests are all conventional techniques.

[0028] Polypropylene: Random copolymer PP; 3080, Taiwan Plastics Industries Co., Ltd. SEBS: S6551, high molecular weight hydrogenated styrene-butadiene block copolymer, linear structure, Zhejiang Zhongli; Filler oil: 45mm 2 / S viscosity, flash point 210℃ paraffin oil, Zhejiang Kanglibo, KP-100B; Carbon nanotubes: CNT001, Shanghai Futai; Conductive carbon black: MK100L, iodine absorption value g / Kg (450-500), Tianjin Moko; Conductive carbon powder: 260g, DBP oil absorption value 190, Yirui stone; Conductive ionic liquid: 1-ethyl-3-methylimidazolium difluoromethanesulfonylimide salt, Keneng Materials; Conductive polyether block compounds: Pebax MV 2080 polyether block amide, Arkema; Other processing aids: Commonly used antioxidants 1010 and 168 are mixed in a 1:1 ratio, and UV stabilizers 2020 and UV-234 are mixed in a 1:1 ratio, with equal amounts of antioxidants and UV stabilizers.

[0029] The preparation of conductive TPE is a current technology, briefly described below: The SEBS rubber was mixed with paraffin oil in a mixer for 1 hour, then allowed to stand for 1 hour to obtain the oil-extended material. Other processing aids, matrix resin, oil-extended material, and conductive components were premixed and fed into the main feedstock. The extruder temperature was controlled in stages. Feeding section: 140-160℃ Melting section: 170-190℃ Mixing section: 180-200℃ Nose section: 190-210℃ 300 rpm.

[0030] The melt is filtered through a perforated plate and then enters a water-cooled strip pelletizer, with the water temperature controlled at 45-60℃. Particle size: 2-3mm in diameter, 3-4mm in length, with good flowability in subsequent injection molding.

[0031] Performance testing: Resistance (Ω): The resistance meter is used to test the two ends of a 120mm×120mm×2mm diagonal, and the resistance should be ≤100. Hardness (A): According to ISO 868, reading at 15s, 70-75 is required; Tensile strength (MPa): ≥5.5 according to ISO 37, 500 mm / min; Heating rate (S): With a constant voltage of 12V, the time required for the room temperature to rise to 80℃ should be less than 30 seconds, and less than 27 seconds for internal control. Appearance: Injection molded 12×12×2mm large square sheet, requiring no aggregation on the surface of the conductive heating TPE (i.e., appearance OK).

[0032] Table 1. Process formulation sheet, kg

[0033] Table 2 Material Properties and Product Appearance

[0034] Table 1 shows the formulations of the comparative examples (hereinafter referred to as "Comparative") and the examples (hereinafter referred to as "Examples"). Table 2 shows the corresponding test results. Test items for which results are not given in the comparative examples are generally those that can be omitted as they are expected, or those that are no longer tested after non-compliance is found. Pure TPE is not conductive and cannot be heated, but it has good mechanical properties and appearance. The addition of conductive materials affects mechanical properties, and some also degrade appearance. The resistance of Comparative Examples 2 and 4 meets the requirements, but carbon materials alone, whether compounded or not, cannot meet the comprehensive qualification of conductivity, heating and appearance. The same is true when conductive carbon powder replaces the conductive carbon black in the comparative examples. Conductive TPE materials with other uses sometimes add metal powder / metal oxide powder. This scheme cannot be used in this invention. Metal powder / metal oxide powder (such as silver powder / copper oxide powder, etc.) makes the appearance poor and does not meet the application requirements of automotive external parts. The hardness and tensile strength of the products in the Examples meet the requirements. In particular, while meeting the requirements of conductivity and heating, they have a good appearance that exceeds people's expectations.

[0035] Figure 1 This is a photograph of a conventionally injection-molded car fuel tank cap, as shown in Embodiment 5 of the present invention. Figure 2 The product of Embodiment 5 of this invention is a 12×12×2mm large square sheet injection molded, and its appearance is qualified.

[0036] Comparison Example Currently available conductive TPEs have relatively low heating capacity; at a constant voltage of 12V, it takes more than 32 seconds to reach 80°C from room temperature. Furthermore, injection molding of large 12×12×2mm square sheets results in appearance defects (see...). Figure 3 These two defects are problems that customers urgently need to solve, especially the latter, which directly renders commercially available products unusable.

[0037] Comparative Example 8 Referring to Example 1, when carbon nanotubes are replaced with carbon black or carbon powder, the heating capacity of the conductive TPE is relatively low. At a constant voltage of 12V, the time to reach 80°C from room temperature is more than 34 seconds.

[0038] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

[0039] The TPE obtained by this invention possesses good electrical conductivity and heating properties while maintaining good physical and mechanical properties, meeting the performance requirements of development and design. It is applicable in solving the problem of parts freezing in winter, and its excellent appearance makes it suitable as a material for automotive exterior parts. The injection-molded large square sheet of the product in this embodiment has no defects or agglomeration in appearance. In contrast, existing TPE injection-molded large square sheets with good electrical conductivity exhibit agglomeration, making them suitable for scenarios where appearance requirements are not high or even nonexistent, but unsuitable for automotive exterior parts.

[0040] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

Claims

1. A conductive heating TPE material, with the following formulation by weight percentage: Polypropylene 12%-20% SEBS 30%-40% Paraffin oil 30%-40% Carbon nanotubes 10%-25% Conductive ionic liquids 1%-5% Conductive polyether block compounds 1%-10% Other processing aids: 1%-3%.

2. The conductive heating TPE material according to claim 1, by weight percentage, has the following formulation: Polypropylene 12%-17% SEBS 30%-36% Paraffin oil 30%-37% Carbon nanotubes 10%-16% Conductive ionic liquids 2%-5% Conductive polyether block copolymers 2%-8% Other processing aids: 1%-3%.

3. The conductive heating TPE material according to claim 1, characterized in that, The conductive ionic liquid is 1-ethyl-3-methylimidazolium difluorosulfonylimide salt, and the conductive polyether block compound is a polyether block amide.

4. The method for preparing the conductive heating TPE material according to claim 1 includes the following steps: melting and mixing the formulation components to obtain the conductive heating TPE material.

5. The method for preparing the conductive heating TPE material according to claim 4, characterized in that, After the raw materials are mixed, they are fed into a twin-screw extruder for melt processing and granulation to obtain conductive and heated TPE material.

6. The use of the conductive heating TPE material of claim 1 in the preparation or as a conductive heating product.

7. The use of the conductive heating TPE material of claim 1 in the preparation or as a conductive heating elastic product.

8. The application of the conductive heating TPE material of claim 1 in the preparation or as a conductive heating automotive product.

9. The application of the conductive heating TPE material of claim 1 in the preparation of or as a conductive heating automotive exterior product; or the application of the conductive heating TPE material of claim 1 in the preparation of or as a conductive heating automotive exterior part.

10. An automotive product, the raw materials for which it is prepared include the conductive heating TPE material of claim 1.

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