I. Background of Material Selection

II. Material Performance Characteristics

1. Food-grade safety certification
   Tested in accordance with FDA 21 CFR 177.1810, this product is free of phthalate plasticizers and heavy metals, can come into direct contact with non-oily foods, complies with the EU EN 71 toy safety standard, and is suitable for sensitive applications such as baby tableware. 17。
2. High liquidity and rapid prototyping
   The melt index reaches 9 g/10 min (2.16 kg at 190℃), enabling rapid filling of thin-walled parts. The injection molding cycle is shortened by 30% compared to conventional TPEs. The molding temperature range is 190–200℃, and the material is compatible with existing PP injection molding lines without requiring any equipment modifications. 18。
3. Excellent bonding performance
   Excellent polarity compatibility with the PP substrate (solubility parameter difference Sp < 0.5); no delamination after a 48-hour boiling water test, with a peel strength ≥ 3.5 N/cm, ensuring that the coating layer remains firmly adhered during long-term use. 15。
4. Mechanical Performance Balance
   Hardness: 60–62 Shore A; tensile strength: 4 MPa; elongation at break: 500%; tear strength: 20 kN/m. It combines a soft tactile feel with excellent impact resistance, effectively absorbing the impact force when a lunchbox is dropped. 1。
5. Weather and temperature resistance
   Temperature resistance range: -40℃ to 120℃. It can withstand high temperatures commonly encountered in daily dining scenarios (such as hot beverages below 80℃). After prolonged use, the elastic recovery rate remains above 90%, and it is unlikely to harden or soften due to temperature fluctuations. 34。

III. Application Advantages

1. Enhance sealing and user experience
   The friction coefficient of the material surface has been optimized, and after coating, the sealing performance between the lid and the box body of the meal container has improved by 40%, effectively preventing soup leakage. The soft tactile feel (Shore 60A) ensures smoother opening and closing operations, with gentle rebound when pressed, reducing hand fatigue. 110。
2. Environmental Protection and Cost Optimization
   Specific gravity ≤ 0.95; single-piece material consumption is reduced by 5-8% compared to silicone. Scrap materials can be 100% recycled, and production energy consumption is 25% lower than that of rubber. Overall costs are approximately 20% lower than those of silicone coating solutions. 116。
3. Design flexibility
   Supports customization in a variety of colors (by adding color masterbatches), enabling special effects such as semi-transparency and fluorescence to meet brand differentiation needs. The thickness of the overmolding layer can be flexibly adjusted between 0.5 and 3 mm, making it suitable for different structural designs. 19。
4. Increased production efficiency
   Using a two-shot injection molding process, the mold cooling system is designed with spiral water channels (temperature difference ≤ ±2℃), reducing the molding cycle to 25–30 seconds. The yield rate of good-quality parts exceeds 98%, significantly lowering the scrap rate. 19。

IV. Key Points of the Production Process

1. Substrate Pre-treatment
   The PP substrate must undergo ultrasonic cleaning, with surface roughness controlled within Ra 0.8–3.2 μm (which can be achieved through sandblasting). Before secondary injection molding, the substrate should be preheated to 60–80℃ to enhance interfacial adhesion. 89。
2. Injection Molding Parameters
   • Hopper temperature: 190–200℃ (heated in three sections, with the rear section slightly lower in temperature)
   • Mold temperature: 40-50℃ (to shorten cooling time)
   • Injection pressure: 80-100 MPa (holding pressure is 60-70%)
   • Holding pressure time: 8–12 seconds (for thin-walled parts) to 15–20 seconds (for thick-walled parts) 19。
3. Quality control
   Adopt a multi-point gating design (such as a subsurface gate) to prevent sink marks from forming in the overmolded layer. Each batch of products must pass a boiling test (95℃ × 2 hours), a drop test (from a height of 1.5 meters), and an FDA migration test to ensure that performance meets the required standards. 115。

V. Market Feedback and Application Expansion

1. Customer reviews
   End-user feedback: “The opening and closing feel is similar to silicone but lighter and more convenient.” Real-world testing by catering chain companies shows that meal boxes coated with EN60D-SPJCH exhibit a 30% improvement in sealing performance and a 50% reduction in damage rates during cold-chain transportation. 110。
2. Industry Applications
   This material has been adopted by numerous food packaging companies. In addition to lunch boxes, it has also expanded into applications such as sealing rings for fresh-keeping containers and handles for children’s tableware. The market share has been growing at an annual rate of over 15%. 17。
3. Technical Extension
   Thanks to its high flowability based on EN60D-SPJCH, this material enables the further development of micro-injection molded products—such as sauce-pack spouts. With a melt index of 9 g/10 min, it supports thin-wall molding down to 0.3 mm, meeting the trend toward lightweight food packaging. 19。

VI. Comparative Advantages Over Silicone

Conclusion