The plastic lunch box can be heated in a microwave oven, but only the No. 5 plastic polypropylene (PP) can be used in the microwave oven.
Plastic lunch boxes are safe for food, but they don't mean heating is safe. Of these plastic packaging boxes, only plastic polypropylene (PP) No. 5 can enter the microwave oven. Polypropylene (PP) is relatively heat-resistant and can withstand high temperatures of around 200 °C, so it can be heated by microwaves and repeated heating does not cause any major problems. The heat resistance of other plastics is much worse. It is best not to heat directly, or to put too hot food, of course, can not be used repeatedly.

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