Generally, the packaging made of paper is collectively referred to as paper-based packaging. The performance of paper-based packaging is high strength, low cost. Wear-resistant packaging is mostly used as shopping bags, document bags, such as kraft paper. The paper surface is smooth and the packaging paper with higher strength is mostly used for labels, clothing tags, bottle stickers, such as bleached paper. Supported by natural raw materials, non-toxic, high transparency, smooth surface, tensile, moisture-resistant, oil-proof packaging paper, mostly used for food packaging, such as cellophane. The manufacturing raw materials of cardboard are basically the same as paper. The main difference is the hardness, thickness, strong rigidity, and easy processing. As a modern packaging material, paper is mainly used to make packaging products such as cartons, boxes, paper bags, paper containers, etc. Among them, corrugated cardboard and its cartons occupy the dominant position of paper packaging materials and products. Composite paper composed of a variety of materials and cardboard, special processing paper has been widely used. And it will partially replace the application of plastic packaging materials in food packaging, in order to solve the environmental protection problems caused by plastic packaging.
Paper packaging have the characteristics of environmental protection, recycling and cost saving. With the increasing environmental protection requirements of packaging in the entire international market, paper packaging are used more and more in the packaging industry. Another feature of paper-based packaging is that it can quickly pass through the commodity inspection gate to achieve the purpose of fast logistics and cost savings.
Because paper packaging materials have the above characteristics, the using amount of paper packaging materials is increasing, in addition to the above characteristics, but also has the following characteristics:
Firstly, the raw material source is extensive, the cost is low, the variety is diverse, easy to go ahead the mass production.
Secondly, Paper and cardboard have strong ability to absorb and bond ink and have good printing performance. Therefore, they are often used as printing surfaces in packaging. The printing properties of paper and cardboard are mainly determined by surface smoothness, sizing, elasticity and adhesion.
Thirdly, paper and cardboard have good processing performance, which is convenient for composite processing and molding. It can be made into various shapes, and can also be folded. Various sealing methods can be used. It is easy to process into packaging containers with various properties, and it is easy to realize mechanization. Processing operations, there are already mature production processes. Good processing performance makes it possible to design various functional structures (such as windows, handles, partitions and design display stands, etc.). In addition, through appropriate surface treatment, paper and cardboard can be provided with necessary moisture resistance, insect resistance, barrier properties, heat sealing properties, strength and physical properties, etc., and their application scope can be expanded.
Fourthly, paper and cardboard have certain strength, stiffness and mechanical adaptability, and its strength is mainly determined by the material, quality, thickness, processing technology, surface condition and certain temperature and humidity conditions of the paper; in addition, paper also has A certain degree of folding, elasticity and tearing, etc., suitable for making shaped packaging containers or wrapping. Ambient temperature and humidity have a great influence on the strength of paper and cardboard. Changes in air temperature and humidity will cause changes in the balance of moisture in paper and cardboard, and ultimately change their mechanical properties to varying degrees. The mechanical properties of paper change with relative humidity. Because paper fibers have greater water absorption, when the humidity increases, the tensile strength and tear strength of the paper will decrease, which will affect the usability of paper and cardboard. A relative temperature and humidity condition must be maintained when measuring the mechanical properties of paper and cardboard.
Fifthly, paper and cardboard are porous fibrous materials, which have a certain degree of permeability to moisture, gas, light, grease, etc., and their barrier properties are greatly affected by temperature and humidity. Single paper packaging materials generally cannot be used to package foods with high moisture and oil content and high barrier properties, but can meet the barrier properties requirements through appropriate surface processing.
Sixthly, paper and cardboard are hygienic and safe, because the special structure of paper fibers can also be used for fruit and other packaging that requires ventilation. Paper packaging products can be recycled and reused, so energy saving and environmental protection, no white pollution.