I. Project Background and Requirements Analysis

End product Children's eyeglasses (frames)
Processing method Injection molding at 240℃ (for individual molded parts)
Substrate compatibility It can be used as a standalone material or combined with ABS/PC via overmolding.

 

Core Performance Requirements ：

1. High hardness 60-65 Shore D, ensuring structural rigidity.
2. Excellent weather resistance Children use it frequently outdoors, so it needs to be UV-resistant and resistant to yellowing.
3. Wear and scratch resistance It is resistant to scratches during daily use and wiping.
4. High surface quality The material is clean and free of black spots, meeting the appearance requirements.
5. Good hand feel and formability Comfortable to wear, with high injection molding efficiency.

II. Technical Parameter Objectives

III. Development Process and Solution Optimization

Initial Sample Issue Analysis

Identification of Technical Challenges ：

1. The balance between hardness and toughness While achieving an ultra-high hardness of 65D, it is also necessary to maintain sufficient toughness to meet the safety requirements for children's products.
2. Synergy between hardness and wear resistance High hardness does not directly equate to high wear and scratch resistance; it requires specialized material design.
3. Formability under high hardness High-hardness TPEE melt typically has a relatively high viscosity, so it’s essential to ensure good fluidity at 240℃.
4. Appearance and Weather Resistance It is necessary to simultaneously ensure material purity (free of black spots) and long-term resistance to UV aging.

Successful Approach: Design Philosophy for the TE65D-ETYJ Formulation

1. Base Material and Hard Segment Regulation A TPEE matrix of a specific model is carefully selected, and by optimizing the content of hard segments and crystallinity, a highly rigid network skeleton is constructed, laying the foundation for high hardness.
2. Wear-resistant reinforcement system A synergistic system combining specialized siloxanes with micro- and nano-sized wear-resistant additives has been introduced, significantly enhancing surface scratch resistance without substantially affecting transparency or toughness.
3. Flow and Processing Additives Add efficient internal lubricants and ester-based processing aids to reduce melt viscosity and improve the mold-filling flowability of high-hardness formulations during injection molding.
4. Weathering and Stabilization Design It is formulated with a combination of high-performance UV absorbers and antioxidants to ensure that the material remains colorfast and does not become brittle even after prolonged outdoor use. Additionally, fine filtration guarantees that the material is pure and free of impurities.

IV. Verification of Material Properties of TE65D-ETYJ

Results of Physical and Mechanical Property Tests

Processing and Application Performance

• Processing performance At 240℃, the injection molding exhibits good flowability, complete filling, and smooth demolding; the molded parts have low internal stress and are resistant to deformation.
• Appearance quality The material is pure, and after injection molding, the finished product has a smooth surface free of defects such as black spots or flow marks.
• Specialized Test ：
  • Abrasion and Scratch Resistance Test (Steel wool weighted friction): The number of visible scratches is significantly fewer than that of TE65D-FH, meeting customer standards.
  • Weathering test (UV Aging): After 500 hours, the yellowing index ΔYI < 2, and the retention rate of mechanical properties is >90%.
  • Handfeel and Safety It has a comfortable surface feel and, although it’s highly rigid, it has passed the relevant toughness and safety tests for children’s products.

V. Summary of Key Technical Points

This project has successfully developed a high-hardness TPEE material, TE65D-ETYJ, suitable for children’s eyeglass frames. The key breakthrough lies in:

1. Multi-performance balance Achieved a combination of ultra-high hardness (64-66 D) with excellent toughness and wear resistance.
2. Functional Design For children’s products, we have enhanced weather resistance and surface scratch resistance, and ensured high material purity.
3. Processing adaptability The optimized formulation ensures a favorable injection molding processing window even at high hardness levels.

Conclusion The TE65D-ETYJ material perfectly meets the stringent requirements of children’s eyewear for high rigidity, durability, safety, and aesthetics. It successfully resolves the previous contradiction found in preliminary trials—“sufficient hardness leads to poor wear resistance, while excellent performance results in low hardness”—providing a reliable solution for high-demand structural components made from transparent or light-colored rigid elastomers.