In the realm of thermoplastic elastomer (TPE) manufacturing, the selection and integration of fillers play a pivotal role in shaping the final product’s properties, from mechanical performance to cost-effectiveness. This article explores six common fillers used in TPE granulation, detailing their functions, optimal addition amounts, compatibility challenges, and practical processing tips to help manufacturers achieve superior results.
1. Calcium Carbonate (CaCO₃): Balancing Cost and Hardness
Role: A primary cost-reducing filler, calcium carbonate also enhances hardness, dimensional stability, and filler loading capacity.
Recommended Dosage:
- Standard grades: 10–50% (by mass), ideal for applications requiring rigidity.
- Nano-scale (light calcium carbonate): 5–20% to maintain mechanical properties without compromising flexibility.
Compatibility Considerations: - Nano-sized particles tend to agglomerate, necessitating surface modification with titanate or aluminate coupling agents to improve dispersion in TPE matrices.
- Excessive loading (>30%) can reduce tensile strength and elongation at break, highlighting the need for careful dosage control.
2. Talcum Powder: Boosting Rigidity and Heat Resistance
Role: Enhances rigidity, heat resistance, and dimensional stability, making it suitable for automotive interiors and appliance casings.
Recommended Dosage: 10–30%. High loadings (>30%) may compromise toughness, requiring a balance between stiffness and flexibility.
Compatibility Considerations:
- Surface treatment with silane coupling agents (e.g., KH-570) is critical to improve adhesion with PP/SEBS bases. Unmodified talcum powder can diminish TPE’s impact resistance and flexibility, underscoring the importance of pre-processing modification.
3. Silica (SiO₂, Fumed Silica): Enhancing Wear and Tear Resistance
Role: Boosts 耐磨性 (wear resistance), tear strength, and weather resistance, essential for applications like shoe soles and seals.
Recommended Dosage: 5–15%. Exceeding this range increases melt viscosity, hindering processability.
Compatibility Considerations:
- Poor dispersion in non-polar SEBS/PP systems calls for silane coupling agents (e.g., KH-570) or compatibilizers to ensure uniform distribution and prevent processing issues.
4. Carbon Black: For Conductivity and UV Protection
Role: Provides electrical conductivity, anti-static properties, UV resistance, and coloring, widely used in cables and automotive parts.
Recommended Dosage: 2–10%. High loadings (>15%) drastically reduce elongation, making it unsuitable for flexible applications.
Compatibility Considerations:
- Prone to agglomeration, requiring high-shear mixing to achieve proper dispersion. Avoid using it in transparent products, as it compromises clarity.
5. Kaolin: Cost-Effective Insulation and Chemical Resistance
Role: Reduces costs while improving electrical insulation and chemical resistance, ideal for wire/cable and electronic components.
Recommended Dosage: 5–20%. Modified kaolin (e.g., treated with KH-550) can enhance tensile strength.
Compatibility Considerations:
- Hydrophilic nature leads to interface defects if unmodified; silane coupling agents are necessary to reduce water absorption and improve matrix adhesion.
6. Glass Fiber (GF): Engineering Strength and Rigidity
Role: Dramatically enhances mechanical strength, rigidity, and heat resistance for structural components.
Recommended Dosage: 10–30%, with long fibers offering superior reinforcement (requires specialized screw designs for proper dispersion).
Compatibility Considerations:
- Surface treatment with amino-silanes is essential to minimize fiber-matrix debonding. High loadings may reduce impact toughness, mitigated by adding toughening agents like POE (polyolefin elastomer).
Processing Tips for Optimal Performance
- Filler Modification Methods:
- Dry Modification: Blend fillers with coupling agents in a high-speed mixer at 60–120°C for uniform coating.
- Wet Modification: Pre-disperse fillers in solvents (e.g., ethanol + silane) for better surface treatment, especially for nano-scale particles.
- Process Adjustments:
- Increase screw speed and melt temperature when using high filler loadings to improve dispersion and prevent shear-induced defects.
Conclusion
Selecting the right filler for TPE granulation requires a strategic balance between target properties, cost, and processing feasibility. While fillers like calcium carbonate and kaolin offer cost-effective solutions, engineering-grade additives like glass fiber demand careful surface modification and process optimization. By understanding each filler’s unique behavior—including optimal dosages, compatibility challenges, and modification techniques—manufacturers can tailor TPE compounds to meet the rigorous demands of applications ranging from automotive parts to consumer goods.
For more insights on raw materials (e.g., SIS, SBS, SEBS, SEPS, SSBR) or industry trends, connect with our experts to explore tailored solutions and stay ahead in TPE innovation.
During the TPE granulation process, the choice and addition amount of fillers have a significant impact on the performance of the final product. Different fillers can improve properties such as hardness, strength, wear resistance, heat resistance, and cost, but they may also affect processing performance and compatibility. The following are the application scenarios, recommended addition amounts, and compatibility analysis of common fillers:1. Functions, Dosages and Compatibility of Several Typical Fillers
1. Calcium carbonate (CaCO₃)
- Applicable requirements: reduce costs, increase hardness, improve dimensional stability, and increase the filling amount.
- Recommended addition amount: Usually 10% – 50% (mass fraction), and a small amount of light calcium carbonate (nano – scale) can be added (5% – 20%) to maintain mechanical properties.
- Compatibility problem:
- Nanoscale calcium carbonate is prone to agglomeration and needs to be modified with coupling agents (such as titanate and aluminate) to improve its compatibility with TPE. Generally, when a small amount of calcium carbonate is added (such as less than 20%), surface modification may not be necessary.
- Excessive amount ( > 30%) will lead to a decrease in tensile strength and elongation at break.
2. Talcum powder
- Applicable Requirements: Improve rigidity, heat resistance, and dimensional stability (such as automotive interiors, home appliance casings).
- Recommended addition amount: 10% – 30%. High filling (>30%) will affect toughness.
- Compatibility issues
- Surface modification (such as silane coupling agent KH-570) is required to enhance the binding force with the PP/SEBS matrix.
- Unmodified talcum powder will reduce the flexibility and impact strength of TPE.
3. White carbon black (silica, SiO₂)
- Applicable Requirements: Enhance wear resistance and tear resistance (such as soles, seals), and improve weather resistance.
- Recommended addition amount: 5% – 15%. Excessive amount will increase the melt viscosity and affect the processing fluidity.
- Compatibility issues
- It has poor dispersion in the non-polar SEBS/PP system. When the amount is relatively large, it needs to be used in combination with a compatibilizer and a silane coupling agent KH-570.
4. Carbon black
- Applicable demands: Conductive/antistatic applications, UV protection, coloring (such as cables, automotive components).
- Recommended addition amount: 2% – 10%. High addition amount (>15%) will significantly reduce the elongation rate.
- Compatibility issues
- It is prone to agglomeration and high-shear mixing is required to ensure dispersion.
- It may affect the transparency of TPE (avoid using it if transparent products are required).
5. Kaolin
- Applicable requirements: Reduce costs and improve insulation and chemical resistance (such as in wire and cable, electronic components).
- Recommended addition amount: 5% – 20%. Modified kaolin can improve tensile strength (such as treatment with KH-550).
- Compatibility issues
- It needs to be modified with a coupling agent (such as silane), otherwise it is prone to absorb water and cause interfacial defects.
6. Glass Fiber (GF)
- Applicable requirements: Significantly improve strength, rigidity, and heat resistance (such as in engineering structural components).
- Recommended addition amount: 10% – 30%. Long fiber reinforcement has a better effect, but a special screw design is required.
- Compatibility issues
- Surface infiltration treatment (such as amino silane) is required to reduce the fiber-matrix interface peeling.
- High content will reduce the impact toughness, and a toughening agent (such as POE) is required.
II. Corresponding process description:
- Methods for Filler Modification:
- Dry modification: Blend with coupling agent in a high-speed mixer (60 – 120℃).
- Wet modification: Predisperse in a solvent (such as ethanol + silane).
- Processing adjustment:
- When highly filled, the screw speed and melt temperature need to be increased to improve the dispersibility.