Can PP lunch boxes be microwaved?

Source:pulixin By Administrator Posted:2022-10-28
Nowadays, we are exposed to more and more plastic products and disposable lunch boxes, but some products are made of No. 5 PP material, which can be heated in a microwave oven. Because this material is made of polypropylene as a raw material, it is more resistant to high temperatures than other materials.

The disposable lunch box made of No. 5 PP is a thermoplastic resin material and can be heated in a microwave oven, which is more environmentally friendly than other products. And the raw material of this material product is polypropylene, which is relatively safe, but note that each plastic has a heat-resistant limit, and the temperature should not be too high during use.
Polypropylene (PP) is one of the five general-purpose plastics. It is a semi-crystalline thermoplastic polymerized from the monomer propylene. Polypropylene has a wide range of applications in industry and life, including fiber textiles (such as ropes, thermal clothing and carpets, etc.), plastic containers, packaging materials and labels.

● Relatively low density
High impact resistance, strong mechanical properties
● Various organic solvents and acid-base corrosion
Heat resistance, melting point 160~166℃, products can be sterilized by steam
● high chemical stability
Polypropylene becomes brittle when the ambient temperature is below 0°C
● Colorability is not good, but can be modified by additives

PP plastic sheet occupies an extremely important position in packaging materials.
According to the different processing technology, polypropylene film can be divided into cast film (CPP), biaxially oriented film (BOPP) and blown film (IPP).

CPP film is a non-stretching, non-oriented flat extrusion film, which has the characteristics of light weight, high transparency, good flatness, good rigidity, strong mechanical adaptability, heat sealing, etc., and is the most widely used in food packaging.

BOPP film is made by co-extrusion of polypropylene particles to form sheets, and then stretched in both vertical and horizontal directions. It has the advantages of light weight, non-toxic, odorless, moisture-proof, high mechanical strength, good dimensional stability, good printing performance, good transparency, low temperature resistance, etc. It is the most widely used printing film at present.

IPP film is a polypropylene film produced by down-blown water-cooled film technology. The modified IPP film has high impact resistance at low temperature, high slip, high transparency, high impact strength, good toughness, and antistatic properties. Mainly used for the packaging of fried snacks, bread, textiles, folders, record sleeves, etc.


At present, there are many products made of No. 5 PP material on the market, such as various plastic products and higher-grade plastic tea sets, tableware, some beverage bottles and so on. The following points should be paid attention to when heating this material product in a microwave oven:

1. High temperature resistance, and at the bottom of the material container, there will be a small circular triangle with numbers written in it, and this type of lunch box can be placed in the microwave oven;

2. No. 5 PP material is now only a plastic box that can be put into a microwave oven, and can be reused if it is carefully cleaned;

3. But note that the lids of some No. 5 PP lunch boxes are made of No. 1 PE, and the lids must be removed before placing them in the microwave.

The melting point of No. 5 PP material is as high as 167°C, while the maximum temperature of the microwave oven is 100°C. There is no need to worry about whether the material will melt when heating. In addition, PP will not produce toxic substances after melting, but lunch boxes made of this material can only hold hot soup, and it is best not to heat food with a lot of oil. This is mainly because the boiling point of the oil is above 200°C, which has exceeded the melting point of the material.

In addition, it should be noted that except for No. 5 PP material, other numbers of plastics will be more or less harmful when heated in a microwave oven. For example, polyvinyl chloride made of No. 3 material contains 30% to 40% of plasticizers, which will penetrate into food after heating and produce carcinogens.

How long can PP be heated in the microwave

Under normal circumstances, 5-10 minutes is enough, but pay attention to the thickness of the lunch box when heating. Generally, thin disposable lunch boxes are best heated within 5 minutes, while PP lunch boxes are thicker than disposable lunch boxes and can be heated for 1-10 minutes.

In addition, if there is a lot of oil in the food, it is recommended to shorten the cooking time. This is mainly because the boiling point of the oil is very high, and it is easy to be dangerous when heated for a long time.

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