The hottest fast food packaging has become a new h

Fast food packaging has become a new bright spot in the development of food industry (3)

packaging materials for microwave food

with the rapid development of microwave technology and the popularity of microwave ovens seeking non proportional stress only when the material has no obvious yield point, microwave food, as a convenient food, is more and more welcomed by the broad masses of the people, and the importance of microwave food packaging materials is also increasing day by day. All packaging materials that can pass through microwave have the basic conditions for microwave heating, but the ideal packaging materials for microwave food must also have the following conditions in addition to passing through microwave

heat resistance

the most basic requirement of containers for microwave ovens is that they must have good heat resistance. Considering the different heating processes of various microwave foods in the heating process, the boiling point of water is 100 ℃, the temperature is raised to 100 ℃ and the constant temperature is maintained for a period of time until all the water volatilizes and escapes. Therefore, the heat resistance requirements of microwave oven containers for water-based foods are low, but should not be lower than 100 ℃ because the medical devices containing PVC will release harmful chemicals during routine use and waste treatment. Since the boiling point of oil is above 200 ℃, there will be no constant temperature stage in the lower temperature range during the heating process until the boiling point of oil, so the microwave oven container for oily food has high requirements for heat resistance. Therefore, the microwave oven container for oily food should be able to withstand at least 10 minutes of heating treatment at about 130 ℃

cold resistance

in order to extend the shelf life of microwave oven foods, frozen storage is often used. Therefore, in addition to heat resistance, the substrate of microwave oven containers must also consider its cold resistance. The microwave oven container shall be able to withstand low temperature of -18 ℃ - -20 ℃

oil resistance

containers for microwave ovens often need to contact edible oils. Therefore, except for disposable microwave containers for water-based foods, they should have good oil resistance

hygiene

containers for microwave ovens often come into direct contact with food in the process of use, so the materials selected must have reliable hygiene and reanalysis performance of the curve, and meet the requirements of relevant national health standards

low price

microwave oven container is a popular daily necessities. Therefore, under the conditions of the same or similar use performance, we should choose materials with relatively low price as far as possible to improve market competitiveness

waste is easy to handle

the packaging container of microwave food is a disposable product, so waste disposal is a problem that needs attention. Materials that are easy to recycle should be selected as far as possible. Plastics not only have microwave transmission properties, but also have a wide variety, which can meet the above basic requirements. In addition, plastic generally has the characteristics of small heat capacity. When using plastic microwave food packaging materials, it also has the advantages of fast heating and energy saving. Therefore, plastic microwave food packaging materials have developed rapidly. The packaging materials used are as follows:

polyethylene containers. The outstanding advantages of these containers are excellent cold resistance, low temperature below -40 ℃, reliable sanitary performance, and acceptable oil resistance. They are used to hold oily food for a short time or generally will not cause problems at low temperature. In addition, it also has the advantages of convenient molding and low cost, and the waste is also easy to recycle (it can produce recycled products after granulation or burn to recover heat energy). However, its high temperature resistance is poor. Polyethylene containers will deform at about 100 ℃ and melt at above 120 ℃, so the use effect is not ideal

polypropylene containers

pure polypropylene microwave oven containers are made of polypropylene homopolymers or block copolymers. When block copolymers are used, the cold resistance of the containers is significantly improved and can withstand low temperatures below -20 ℃. The heat resistance of block copolymer is worse than that of homopolymer, but the heat resistance of both is above 110 ℃. For the cooking of water-based microwave food, there is no problem of heat resistance; For oily food, its heat resistance is not enough

filled polypropylene container. Filled polypropylene containers for microwave ovens are mostly filled with talc powder. The blending of talc powder has the dual functions of improving heat resistance and rigidity, and shortening the production cycle, so as to achieve the purpose of reducing the container cost. The amount of talc powder used in the packed polypropylene microwave oven container is generally about 30%, and the heat resistance of this container is above 130 ℃; For some kinds of filled polypropylene microwave oven containers, the filler content is about 50%, the heat resistance is 140 ℃, and the low temperature of -30 ℃

polyester container

the practical polyester microwave oven container is a thermoformed container made of crystalline polyethylene terephthalate sheet, i.e. CPET container. The highest heat-resistant temperature of this container is 230 ℃, which is an extremely rare plastic product; CPET has the advantages of oil resistance, chemical resistance, low temperature performance, sanitary reliability and easy recycling of waste materials. It is a very ideal plastic container for microwave ovens. However, this product is technically difficult and costly, and it is still to be developed in China

ps containers

heat resistant PSP containers use PS sheets and heat-resistant plastic films, and heat-resistant styrene copolymers or polystyrene alloys can also improve the heat resistance of polystyrene. According to the literature, the heat resistance of polystyrene sheet can be improved to 130 ℃ -135 ℃ by compounding heat-resistant film on polystyrene sheet, and the alloy polystyrene sheet can also reach a considerable level. The problem is how to reduce the production cost to expand the market

heat resistant BOPS container. The heat resistance of heat-resistant biaxially stretched polystyrene sheet can reach the level close to 120 ℃, which is suitable for the application in microwave oven containers. When filled polypropylene microwave oven containers are used, heat-resistant BOPS sheets are often used as the cover of the container in order to facilitate the observation of the contents of the container

in addition to the above-mentioned plastic containers for microwave ovens, the micro experimental steps developed abroad include pet alloy microwave oven containers, which are characterized by good heat resistance (about 110 ℃), good transparency, comparable to polycarbonate micro wave oven containers, low price, stronger economic competitiveness, and are worthy of attention