Paper and Paperboard
Paper and paperboard became important printing and packaging materials around the 1900s.They have the following advantages: · produced in many grades and forms ·recyclable and biodegradable ·easily combined with other materials to make coated or laminated packs ·produced with different degrees of opacity Paper qualities mainly differ in their surface treatment, such as coated or uncoated,textured or glossy. They are selected according to the purpose they need to fulfill.For example, uncoated paper has low reflection compared with high-gloss coated paper. The former is ideal for normal book printing, while the latter the choice for high-quality brochures.
Paper can also be subdivided into fine and coarse papers.Fine papers are used for printing books and magazines, and coarse papers for packaging.Paperboard is typical of coarse papers.It is a kind of multi-layer material, the inner layer of which is usually made from recycled fibers.Corrugated board is a widely used type of paperboards to make containers because it is light, strong and easily changed for all products.
Plastic Materials
The use of plastics in packaging has accelerated rapidly since the 1970s,in large part because of their unique features: flexible, light weighted,cost-effective, durable, unbreakable, hygienic and safe. Plastic has many variations, such as PVC in food packaging, or PET, a glossy film used for microwave trays and semirigid containers In printing, the selected plastic substrate usually determines the printing process to be used or the printing process could help determine the substrate.
Metal Materials
Aluminum foil was adopted for packaging shortly after its initial production in 1913. As one of the major flexible packaging mmaterials, it finds uses as a wrapper for a varietyof products. Aluminum foil is generally laminated to paper or plastic films to increase ruggedness. When laminated to a polyester film, it becomes metallized polyester, which has outstanding barrier properties and good printability. Glass Glass is a rigid packaging material that does not alter its characteristics with the passage of time, nor does it need additional treatment to make it impervious. Although glass is heavier and more breakable than plastic and aluminum containers, it will remain an important packaging material for certain products because it is durable and transparent.