It can be heated in a microwave oven. In fact, the plastic boxes sold in the market have certain heat resistance, but they all have heat resistance limits. Plastic lunch boxes suitable for microwave heating are generally made of polypropylene or polyethylene. The heat resistance limit of polypropylene is about 140℃, while that of polyethylene is 1 10℃. It should be noted that plastic boxes made of these two materials can be heated by microwave oven, but once they exceed the temperature range they can withstand, they will also produce toxic and harmful substances. Microwave ovens are often used by us. We must choose the ones with guaranteed quality. Generally speaking, the quality of big brands is guaranteed. When buying a plastic lunch box that can be heated by microwave oven, look for the pp5 sign at the bottom of the lunch box. Only products with this logo can be heated by microwave oven, but it also needs to be within the shelf life. And for the sake of health, it is best not to use plastic lunch boxes for high-temperature heating for a long time.