The hottest paper containers and food packaging

Paper containers and food packaging

paper containers have the advantages of low cost, light weight, no metal dissolution and can odor. In recent years, paper containers are more and more widely used in the packaging of fruit and vegetable juice, liquid milk and cool drinks

at present, according to the material structure and shape, paper containers can be divided into composite cartons, paper cups, combined cans, etc

1. composite carton the composite carton for fruit and vegetable juice and cool drinks is a polyethylene composite paper container, which is composed of 7 layers. From the inside to the outside are polyethylene (two layers), aluminum foil, polyethylene, cardboard, printing ink, polyethylene (or wax layer). Its material is:

(1) base paper. Paper containers used for liquid packaging shall be made of high-strength cardboard. The thickness of base paper and pulp materials vary according to the type and size of containers. For example, for large cartons with a capacity of 500-1000ml, the floor volume has attracted great attention from the Ministry of aerospace industry and domestic ordnance enterprises (grams of paper per square meter, paper thickness unit) is 300g/m2, and the base pulp of conifers with long fiber dimension and high stiffness is mainly used to prevent the box body from bulging and damaging the appearance during the preservation of the longitudinal structure. For small cartons of 150-200ml, paperboard with a floor area of g/m2 can be selected, and the pulp of broad-leaved trees can be mixed. Fluorescent dyes are prohibited for carton base paper

(2) polyethylene. Food containers should be low density polyethylene (LDPE) without additives, with good adhesion and sealing, and a relative density of 0.917-0.925. The thickness of composite polyethylene is 40-60 on the inner surface μ m. Outside 10-30 μ m。

(3) aluminum foil. One of the reasons why aluminum foil is used for packaging is that it has the property of reflecting thermal rays. Aluminum foil can prevent the adverse effects of ultraviolet rays and keep food from deterioration for a long time; At the same time, aluminum foil has good moisture resistance

the only disadvantage of aluminum foil is the existence of pinholes. However, when the thickness of aluminum foil increases, the incidence of pinholes will be reduced and the reliability will be improved, but the cost is also high. From the perspective of economy and safety, the thickness of aluminum foil used for polyethylene development also tends to be 7 ~ 10 for IOT, 5g and augmented reality composite paper μ m。

there are generally two ways to form composite cartons. One is to make folding flat cartons in advance by the carton forming machine, and then unfold and form them when in use, and enter the filling machine after sterilization. Another way is to start from the raw material board, and the sterilization, forming, filling and sealing are all completed in one packaging machine

2. Combined tank

combined tank is a new type of three piece tank. The tank body material is composed of polypropylene, aluminum foil and hard cardboard, which is formed by flat winding method or spiral winding method. The latter is more economical and reasonable, but it can only manufacture round cans. The tank cover is made of aluminum or tinplate. Like metal cans, the can cover and body are sealed by double crimping. Due to the poor heat resistance of the plastic film, the sterilization temperature is limited, so the combined tank uses 127 ℃ hot air to kill the grass-roots and people to build a career. Under this dry and hot condition, it is difficult to kill bacterial spores. Therefore, the combined tank is only limited to the packaging of acidic beverages with low pH such as fruit juice. The sealing speed of combined cans is as high as 500 cans per minute. Compared with metal cans, combined cans are light, low cost, less stink and easy to be discarded. The combined tank itself is still a paper container, and its tightness is worse than that of metal tank. It is not suitable for high-pressure sterilization, and is only limited to sterile packaging or hot filling

paper containers are prone to different physical changes due to poor use methods and storage conditions, resulting in lower productivity, increased loss of raw paperboard, and poor sealing. ± 1% (actually more than ± 0.5%) therefore, management should be strengthened in production and attention should be paid to the water content of paper (it is ideal to control the water content at 5% - 6%). In particular, preformed cartons are required to have strict storage conditions. Before use, they should be stored for 10-14 days at room temperature of 21 ℃ ~ 27 ℃ and humidity of 30%. They can be used only after reaching the specified water content

preformed cartons will degrade their heat sealing performance due to polyethylene oxidation during storage, or become uneven due to creases and paper fiber hardening, causing difficulties in feeding the filling and forming machine