PET Wankai WK‑821
PET Wankai WK‑821
PET Zhejiang Wankai WK‑821 is a bottle‑grade polyester for mid‑to‑high‑end packaging. It features low acetaldehyde content, superior barrier performance, high transparency and high mechanical strength, especially suitable for applications with high requirements on packaging‑material performance.
Main Applications
Soda‑water bottles, edible‑oil bottles, liquor bottles, pharmaceutical bottles, PET sheets.
Physical Properties
| Property Category | Test Standard | Typical Value WK‑821 | Reference Competitor BG80(Yizheng) |
|---|---|---|---|
| Basic Properties | |||
| Intrinsic Viscosity (IV) | GB/T 17931 | 0.78±0.008 dL/g | 0.80±0.01 dL/g |
| Density (23℃) | ISO 1183 | 1.335 g/cm³ | 1.340 g/cm³ |
| Melting Point (Tm) | DSC | 248℃ | 250℃ |
| Mechanical Properties | |||
| Tensile Yield Strength | ASTM D638 | 58 MPa | 55 MPa |
| Elongation at Break | ASTM D638 | 300% | 250% |
| Dart Drop Impact (23℃) | GB/T 9639 | 190 J/mm | 150 J/mm |
| Barrier Properties | |||
| Oxygen Transmission Rate (23℃) | ASTM F2622 | 0.25 cm³·mm/m²·day | 0.35 cm³·mm/m²·day |
| Water‑Vapor Transmission Rate | ASTM F1249 | 1.8 g·mm/m²·day | 2.2 g·mm/m²·day |
Pre‑drying Process (Moisture ≤25 ppm)
| Parameter | Setting Range | 2025 Updated Key‑points |
|---|---|---|
| Drying Temperature | 155‑165℃ | Gradient dew‑point control:‑50℃ →‑60℃ |
| Drying Time | 3.5‑4.5 h | 30% shorter than conventional PET grades |
| Anti‑yellowing Measure | Nitrogen blanketing(O₂ ≤50 ppm) | Mandatory requirement added in 2025 |
Injection Molding Parameters
| Equipment Section | Temperature Range(℃) | Screw Design Key‑points |
|---|---|---|
| Feed zone (C1) | 245‑255 | Shallow‑flight & large lead; +25% conveying efficiency |
| Homogenizing zone (C2) | 260‑270 | Barrier screw thread;‑15% shear heat |
| Metering zone (C3) | 265‑275 | Strictly avoid＞280℃; optical‑performance sensitive zone |
| Hot runner | 260‑270 | Runner L/D ≤8:1 to reduce residence time |
| Back pressure | 2‑5 MPa | Back pressure＞6 MPa will raise haze by 0.3% |
Blow‑molding Process
| Process Step | Parameter Range | Light‑weight bottle special setting |
|---|---|---|
| Pre‑blow pressure | 6‑8 bar | Low pressure for thin‑wall bottles to prevent piercing |
| Final‑blow pressure | 25‑32 bar | Match with high mold temperature |
| Mold cavity temperature | Bottle body:12‑15℃ Bottle neck:100‑110℃(induce crystallization) |
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| Cycle time | 9‑12 s | 3 s shorter than standard PET |
Note: All information above is for reference only!
