Many new moisture-proof materials have emerged in the field of moisture-proofing
There are many new moisture-proof materials in the field of moisture-proof, which are briefly introduced as follows.
(1) high-density polyethylene processing paper
Polyethylene paper made of kraft paper and high-density polyethylene or low-density polyethylene. It has the toughness and firmness of kraft paper, as well as polyethylene superior dielectric properties, moisture resistance, good mechanical strength and impact resistance. It can still maintain flexibility and chemical stability at low temperatures and resist corrosion of acid, alkali, salt solutions and various organic solvents at certain concentrations and temperatures.
Polyethylene processing paper, especially high-density polyethylene processing paper, is an excellent high-grade moisture-proof packaging materials, moisture-proof performance is better than PVC processing paper and asphalt paper.
For composite moisture-proof materials, due to the humidity of the moisture permeability coefficient of each layer of material has a different degree of influence, that is, the moisture permeability coefficient of each layer of material has a different humidity dependence, in the use of such materials for moisture-proof packaging, should also pay attention to the moisture permeability coefficient of high humidity dependence of the material should be placed on the low humidity side, the moisture permeability coefficient of low humidity dependence of the material should be placed on the high humidity side. For example, for polyethylene processed paper, the polyethylene film layer should be placed on the high humidity side.
(2) Calcium-plastic corrugated paperboard
Corrugated cardboard is a very widely used cardboard in packaging, especially for commodity packaging, and can be used to replace wooden and metal boxes. The content of paraffin wax in moisture-proof paperboard is 30%~45%. This corrugated cardboard has high moisture resistance and its strength is much higher than that of non-impregnated cardboard.
In recent years, due to the development of synthetic resin, a calcium-plastic corrugated board has been produced, which can overcome some of the shortcomings of the original corrugated board. It is moisture-proof, rain-proof, and has high strength. It has been used more and more extensively because of its abundant material sources.
Calcium corrugated board is a plastic paper with calcified filler. It is a plastic packaging material, not a paper packaging material. It is customarily referred to as cardboard compared to kraft corrugated paper. Both kraft corrugated paper and calcium corrugated paperboard are characterized by light weight, high mechanical strength and good moisture resistance. The carton made has good folding performance, small storage space, low transportation cost, and can be reused many times after use and easily recycled. This is a good alternative packaging for green wood transportation.
(3) Moisture-proof flat bonded paperboard
Flat moisture-proof adhesive paperboard is made of moisture-proof raw materials and moisture-proof adhesive, which can meet certain requirements of moisture-proof capacity. Some moisture-resistant flat-bonded boards are obtained by surface polyethylene treatment. Usually, the outer layer of the rolled cardboard is pre-coated with polyethylene coating by spray pressing method and then pressed with the cardboard on a press machine. By this method, flat bonded cardboard with polyethylene coating on one or both sides can be obtained.
Due to the impermeability of the polyethylene layer, adhesives with little water content, such as latex, polyvinyl acetate emulsions and hot melt adhesives, must be used to bond to the paperboard. To improve the moisture resistance of dry bonded cardboard, the outer surface of dry bonded cardboard can also be coated with a beeswax mixture.
Moisture-resistant bonded cardboard packing boxes are mainly used for products with sufficient strength under high humidity, such as cosmetics, vegetables, explosives, various spare parts, hardware products, etc., as well as transit packing boxes for transporting products in cold areas.