White-oil-free thermoplastic elastomer composition as well as preparation method and application thereof

Abstract

The invention discloses a white-oil-free thermoplastic elastomer composition as well as a preparation method and application thereof. According to the composition, the A-B-A type styrene block copolymer and the polyolefin resin are used as matrixes and matched with the halogen-free flame retardant, and mineral white oil in traditional TPE is thoroughly abandoned. The material fundamentally solves the problems of greasy surface, poor adhesive force, strong odor, easy aging, migration pollution and the like caused by oil precipitation, and has the comprehensive advantages of excellent precipitation resistance, excellent secondary processing adhesive force, extremely low VOC (volatile organic compound), aging resistance, high safety and the like. The preparation method is simple and suitable for injection molding, the surfaces of the prepared products such as data lines and the like are permanently dry, printed marks are firm, and the product is particularly suitable for the fields such as high-end consumer electronics, automobiles, medical treatment and mother and baby products with extremely high requirements on cleanliness, safety and durability.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a white oil-free thermoplastic elastomer composition, its preparation method, and its application. Background Technology

[0002] In the traditional design and production practices of thermoplastic elastomer (TPE) materials, mineral oil (commonly known as "white oil") is commonly used as a plasticizer and processing aid to effectively reduce raw material costs, improve processing fluidity, and adjust product hardness. While this classic formulation system met the basic needs of general applications for a considerable period, its inherent defects have become increasingly prominent with the increasing sophistication of downstream applications and the tightening of environmental regulations. Taking data cable products as an example, as high-frequency, long-cycle consumer electronics products, they have extremely high requirements for the surface cleanliness, tactile feel, label durability, and environmental safety of the materials. The core problem with traditional white oil-containing TPEs in practical applications is that the added mineral oil and the matrix resin (such as SEBS) are not bonded by stable chemical bonds, but rather exist in a physical doping form. Under conditions of long-term bending use, changes in ambient temperature, or contact with the user's skin oils, the oil gradually migrates from the material's interior to the surface and precipitates, forming a noticeable oil film, commonly known in the industry as "oil oozing" or "oil seepage."

[0003] This precipitation process triggers a series of interconnected pain points in delicate products like data cables: First, the surface oil film makes the cable feel greasy, easily attracting dust and fabric fibers from pockets, severely impacting appearance and user experience; second, the precipitated oil layer forms a weak interface layer, severely hindering the adhesion of surface-sprayed manufacturer logos, color coatings, or QR code printing, leading to blurred text and coating peeling, affecting product identification and brand image; third, volatile small molecules in mineral oil are continuously released in enclosed spaces (such as packaging bags and car storage compartments), producing an unpleasant "plastic smell" and releasing volatile organic compounds (VOCs). C) Emissions issues make it difficult for traditional TPE to meet increasingly stringent environmental and health standards. Furthermore, the presence of surface oils accelerates the material's sensitivity to ultraviolet light and oxygen, making it more prone to yellowing and embrittlement of the data cable, shortening the product's lifespan. More importantly, the migrating oils may cause swelling, corrosion, or stress cracking in other materials in close contact or wrapped around it (such as earphone silicone sleeves and ABS plastic storage boxes), posing a reliability risk. Finally, from a biosafety perspective, mineral oil components pose a potential risk of skin sensitization, and their use in electronic components requiring long-term skin contact is limited under certain regulations. Therefore, developing a new solution that can completely eliminate oil exudation from the formulation source while maintaining or even improving the overall performance of TPE materials for precision products such as data cables has become an urgent technological need to drive the consumer electronics component industry towards high performance, high reliability, and high added value. Summary of the Invention

[0004] The purpose of this invention is to overcome the above-mentioned defects of existing white oil-containing TPEs and to provide a white oil-free thermoplastic elastomer composition with high cleanliness, strong adhesion, low odor, aging resistance, and high safety, as well as its preparation method and application.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a white oil-free thermoplastic elastomer composition comprising, by weight percentage, the following components:

[0007] ABA-based styrene block copolymers: 20-70%;

[0008] Polyolefin resins: 10-40%;

[0009] Halogen-free flame retardant: 20-60%;

[0010] Other adjuvants: 0.1-10%.

[0011] Preferably, the ABA-based styrene block copolymer has a CAS number of 66070-58-4. The polyolefin resin includes, but is not limited to, polyolefins with a CAS number of 9003-07-0.

[0012] Preferably, other additives include antioxidants and lubricants.

[0013] Secondly, the present invention provides a method for preparing the oil-free thermoplastic elastomer composition, comprising the following steps: premixing the above components in a high-speed mixer according to a certain ratio, and then melt-blending and extruding the mixture through a twin-screw extruder to obtain the oil-free thermoplastic elastomer composition. The process temperature of the twin-screw extruder is controlled at 170-210℃.

[0014] Thirdly, the present invention provides the application of the white oil-free thermoplastic elastomer composition in the preparation of data cable products. The application includes preparing data cables through the following process: after mixing the composition, it is processed into connectors, sheaths, and other components of the data cable by injection molding. Preferably, the injection molding process parameters are as follows:

[0015] Primary injection pressure: 50-70KG / cm²; Secondary holding pressure: 15-35KG / cm²; Total injection pressure: 80-100KG / cm²; Barrel temperature: Upper section 180-200℃, Middle section 185-205℃, Lower section 190-210℃; Injection and cooling times are set according to the specific product size.

[0016] The advantages and beneficial effects of this invention are as follows:

[0017] Compared with existing white oil-containing TPEs, the white oil-free thermoplastic elastomer composition and its products provided by this invention completely solve the problem of oil precipitation. Furthermore, through a specific formulation system and matching precision processing technology, it successfully overcomes key technical bottlenecks such as processing difficulties, high internal stress, and product brittleness caused by the lack of lubrication in traditional oil-free systems, achieving comprehensive optimization of overall performance. Its specific advantages and beneficial effects are as follows:

[0018] (1) Excellent resistance to precipitation and high cleanliness without sacrificing processability and toughness: This invention fundamentally eliminates the problem of oil migration and precipitation through specific polymer component combinations and internal lubrication system design, ensuring that the product surface is permanently dry, dust-free, and non-greasy. Simultaneously, by matching the injection molding process used in the formulation, precise control of the barrel segment temperature (upper section 180-200℃, middle section 185-205℃, lower section 190-210℃) and injection pressure (first pressure 50-70KG / cm², second holding pressure 15-35KG / cm²) ensures excellent material flowability and uniform plasticization during processing, significantly reducing internal stress in the molded product and effectively avoiding the risk of brittleness caused by insufficient lubrication common in oil-free systems. The product maintains a consistent feel and good toughness. It is particularly suitable for light-colored products, precision electronic equipment components (such as data cables), and products that come into direct contact with the skin, requiring high cleanliness and reliability.

[0019] (2) Excellent adhesion for secondary processing: Thanks to the complete elimination of oil precipitation and the stable and dense material surface ensured by the above-mentioned optimized molding process, the material of this invention has extremely strong adhesion to paints, UV coatings, printing inks, adhesives, etc., and performs excellently in cross-cut adhesion tests. This advantage cannot be achieved in traditional oil-containing TPEs. In formulations where white oil is simply removed but the processing technology is not optimized, the adhesion may be unstable due to surface defects or internal stress. This invention successfully solves this contradiction through the combination of materials and processes, which is especially beneficial for the long-term firm adhesion of markings on the surface of products such as data cables.

[0020] (3) Extremely low odor and low VOC release: By eliminating volatile small-molecule mineral oils and through a stabilization process using carefully selected additives within the controlled processing temperature window (170-210°C), the material of this invention exhibits extremely low odor and VOC release during production and use. This not only avoids odor pollution but also makes it easier to meet stringent environmental standards in fields such as automotive interiors, healthcare products, and children's products (e.g., automotive VOC standards, EU toy standard EN71, etc.).

[0021] (4) Excellent aging and weather resistance: The material structure of this invention is stable, and its resistance to ultraviolet (UV) yellowing and thermo-oxidative aging is significantly improved. Its oil-free nature avoids the accelerated aging effect of oil oxidation, and the carefully selected stabilizer system can fully exert its effectiveness under the process conditions, further ensuring that the material can maintain good appearance and physical properties after long-term use, thereby extending the service life of products such as data cables.

[0022] (5) Excellent chemical stability and anti-migration properties: This material not only does not experience oil migration due to its formulation, but also benefits from the uniform and dense microstructure formed by the optimized process. It has higher interfacial stability with other materials it contacts (such as ABS, PC, PS, etc.), effectively avoiding cracking, stickiness, or performance degradation of the contacted materials, resulting in higher assembly compatibility and reliability. At the same time, its own resistance to chemical reagents is also enhanced, ensuring the stability of the data cable when it comes into contact with common liquids in daily use.

[0023] (6) Higher level of hygiene and safety: It does not contain mineral oil ingredients that may cause skin sensitivity or are controversial, and all components in the formula have strictly controlled migration. Combined with the gentle and precise molding process, it minimizes the generation and release of small molecules, making the material more able to meet the high standards of biosafety requirements for food contact materials, medical devices, and baby products. It is also easier to comply with relevant regulations such as FDA, LFGB, and USP, and is also fully suitable for data cable products that come into long-term contact with the skin.

[0024] In summary, the white oil-free thermoplastic elastomer composition of the present invention, combined with the specific preparation process and molding parameters (such as segmented temperature and pressure control), can produce a synergistic effect, resulting in high-quality data cables and other products with high surface cleanliness, strong adhesion, low odor, aging resistance, and no risk of brittleness. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to the embodiments.

[0026] Example 1

[0027] Weigh the following raw materials: 50 parts by weight of ABA-based styrene block copolymer (SEBS), 25 parts by weight of polypropylene (PP) resin, 22 parts by weight of halogen-free flame retardant (nitrogen-phosphorus based), 0.5 parts by weight of di-tert-butyl-p-cresol, and 0.5 parts by weight of polyethylene glycol. Add all the above components to a high-speed mixer and mix for 5 minutes until homogeneous to obtain a premixed material. Dry the premixed material at 85°C for 4 hours, and then use an injection molding machine for molding. The injection molding process parameters are set as follows: primary pressure: 60 kg / cm²; secondary pressure: 25 kg / cm²; total pressure: 90 kg / cm²; barrel temperature: upper section 190°C, middle section 195°C, lower section 200°C; mold temperature: 40°C; injection time: 3 seconds; cooling time: 15 seconds. After coating the conductor, cool and shape it in a water bath, and then traction and winding to obtain a smooth wire.

[0028] Comparative Example 1

[0029] Weigh the following raw materials: 50 parts by weight of ABA-based styrene block copolymer (SEBS), 25 parts by weight of polypropylene (PP) resin, 20 parts by weight of white oil, 22 parts by weight of halogen-free flame retardant (nitrogen-phosphorus based), 0.5 parts by weight of di-tert-butyl-p-cresol, and 0.5 parts by weight of polyethylene glycol. Add all the above components to a high-speed mixer and mix for 5 minutes until homogeneous to obtain a premixed material. Dry the premixed material at 85°C for 4 hours, and then use an injection molding machine for molding. The injection molding process parameters are set as follows: primary pressure: 40 kg / cm²; secondary pressure: 25 kg / cm²; total pressure: 90 kg / cm²; barrel temperature: upper section 190°C, middle section 195°C, lower section 200°C; mold temperature: 40°C; injection time: 3 seconds; cooling time: 6 seconds. After coating the conductor, cool and shape it in a water bath, and then traction and winding to obtain a smooth wire.

[0030] Comparative Example 2

[0031] Weigh the following raw materials: 50 parts by weight of ABA-based styrene block copolymer (SEBS), 25 parts by weight of polypropylene (PP) resin, 22 parts by weight of halogen-free flame retardant (nitrogen-phosphorus based), 0.5 parts by weight of di-tert-butyl-p-cresol, and 0.5 parts by weight of polyethylene glycol. Add all the above components to a high-speed mixer and mix for 5 minutes until homogeneous to obtain a premixed material. Dry the premixed material at 85°C for 4 hours, and then use an injection molding machine for molding. The injection molding process parameters are set as follows: primary pressure: 40 kg / cm²; secondary pressure: 25 kg / cm²; total pressure: 90 kg / cm²; barrel temperature: upper section 190°C, middle section 195°C, lower section 200°C; mold temperature: 40°C; injection time: 3 seconds; cooling time: 6 seconds. After coating the conductor, cool and shape it in a water bath, and then traction and winding it to obtain a wire.

[0032] Experiment 1: Performance Testing

[0033] Hardness testing: Refer to ASTM D2240, "Standard Test Methods for Rubber Properties—Hardness Tester". Use a Shore A hardness tester. Place a flat sample (thickness ≥ 6 mm) on a hard platform, ensuring the test surface is smooth and free of defects. Press the indenter foot of the hardness tester firmly and quickly onto the sample surface, reading the instantaneous value within 1 second, or the stable value after a specified time (e.g., 3 seconds). Perform at least 5 measurements at different locations on the sample, and take the average value as the final hardness value.

[0034] Tensile strength and elongation at break tests: Refer to ASTM D412, "Tensive Testing of Vulcanized Rubber and Thermoplastic Elastomers," using a universal testing machine. Accurately clamp both ends of a standard dumbbell-shaped specimen (typically a molded or punched sheet approximately 2 mm thick) in the fixture. Set the tensile speed to 500 mm / min (adjustable according to the standard). Start the testing machine and continuously stretch the specimen until it breaks. The equipment automatically records the force versus displacement (or elongation) curve throughout the process. Tensile strength is calculated by dividing the maximum force at break by the original minimum cross-sectional area of ​​the specimen (unit: MPa). Elongation at break is calculated by dividing the elongation between gauges at break by the original gauge length (unit: %). At least 5 valid specimens are required for each test group, and the results are the arithmetic mean.

[0035] Specific gravity test: Following ASTM D792, "Standard Test Method for Determination of Specific Gravity and Density of Plastics by Displacement Method," the water displacement method (Archimedes' principle) was used. First, the mass (m) of the dried sample was weighed in air. air The sample is then immersed in distilled water, and air bubbles are eliminated using an auxiliary device (such as a fine wire mesh basket). Its apparent mass in water (m) is then measured. water Specific gravity (SG) is expressed by the formula SG=m air / (m air -m water The calculations are as follows. Tests are typically conducted at room temperature.

[0036] Thermal aging test: Aging treatment was carried out in accordance with ASTM D573 "Standard method for aging test of rubber in air oven". Performance tests before and after aging were conducted in accordance with ASTM D412.

[0037] The results are shown in Table 1 below:

[0038] Table 1

[0039]

[0040] As can be seen from the data in Table 1, Example 1 (white oil-free formulation + optimized process) is significantly better than Comparative Example 2 (white oil-free formulation + unoptimized process, 12.56 MPa) in tensile strength (14.98 MPa), and also higher than Comparative Example 1 (white oil-containing formulation, 13.88 MPa). This indicates that the oil-free formulation of the present invention, combined with a specific high-pressure, fully cooled injection molding process (single pressure 60 KG / cm², cooling time 15 seconds), can effectively construct a denser material structure, thereby improving rigidity. Comparative Example 1 has the highest elongation at break (415%) due to the plasticizing effect of white oil. Although Example 1 (275%) is lower than this, compared with Comparative Example 2 (356%), it still maintains a moderate degree of flexibility after removing white oil through optimized process, achieving a better balance between strength and toughness. Crucially, after thermal aging, the strength and elongation retention rates of Example 1 (86.92%, 90.37%) were slightly lower than those of Comparative Example 1 (103.17%, 95.37%) under the short-term "thermal buffering" effect of white oil, but significantly higher than those of Comparative Example 2 (82.10%, 87.05%) due to process mismatch. This verifies the decisive role of process optimization in achieving long-term thermal stability of the oil-free system. Therefore, the core advantage of Example 1 lies in the synergy between the white oil-free formulation and specific high-pressure, segmented temperature control, and sufficient cooling processes. While eliminating the fundamental defect of oil precipitation, it successfully overcomes the process difficulties of easy brittleness and insufficient thermal aging stability in oil-free systems, achieving a comprehensive balance of high cleanliness, strong adhesion, excellent durability, and reliable processability. It is particularly suitable for high-end electronic components such as data cables that have stringent comprehensive performance requirements.

Claims

1. A white oil-free thermoplastic elastomer composition, characterized in that, By weight percentage, it comprises the following components: 20-70% ABA-based styrene block copolymer; 10-40% polyolefin resin; and 20-60% halogen-free flame retardant. Other adjuvants: 0.1-10%.

2. The white oil-free thermoplastic elastomer composition according to claim 1, characterized in that, The ABA-type styrene block copolymer is SEBS.

3. The white oil-free thermoplastic elastomer composition according to claim 1, characterized in that, The polyolefin resin is polypropylene or polyethylene.

4. The application of the white oil-free thermoplastic elastomer composition according to any one of claims 1-3 in the preparation of data cable products, comprising raw material preparation and mixing, injection molding, cooling and setting, and post-treatment, characterized in that, The injection molding process parameters include: primary injection pressure 50-70KG / cm², secondary holding pressure 15-35KG / cm², total injection pressure 80-100KG / cm²; barrel temperature 180-200℃ for the upper section, 185-205℃ for the middle section, and 190-210℃ for the lower section.

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