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Development and application of green moisture-proof packaging paper

many goods (or products) will be moldy, damp, deteriorated, rusted, etc. when affected by external moisture during storage and transportation, which will damage the quality of goods. For example, the quality of crispy food, medicine, precision instruments and meters will decline after being affected by moisture. Therefore, for those products whose quality will be affected after moisture absorption, it is very necessary to apply moisture-proof packaging

the function of moisture-proof packaging is to slow down or block the speed of external moisture entering the packaging through high moisture resistance packaging materials, or at the same time absorb the moisture penetrating into the packaging with desiccant, so as to maintain the moisture content of goods and obtain a certain storage period. At present, the general moisture-proof packaging can obtain certain moisture-proof packaging requirements by using moisture-proof paper packaging or plastic film packaging with high moisture resistance. However, for puffed food or other high-grade commodities with high moisture-proof requirements, desiccants need to be sealed to ensure the quality requirements of food flavor or crispness

moisture proof packaging materials refer to packaging materials that cannot or are difficult to penetrate water vapor. Commonly used moisture-proof packaging materials include paper, plastic, metal, glass, ceramics, etc. In addition to the functions of ordinary packaging materials, the special requirements of moisture-proof packaging materials are low moisture permeability. The smaller the moisture permeability of moisture-proof materials, the better the moisture-proof performance. Commonly used moisture-proof paper packaging materials include moisture-proof glass paper, paraffin paper, PVC processing paper, asphalt waterproof paper, polyethylene processing paper, aluminum-plastic composite moisture-proof paper, moisture-proof corrugated board, etc. Various moisture-proof materials are generally made by adding unbleached sulfate chemical pulp or coating various moisture-proof chemicals on the surface of the paper, such as carboamide resin, latex, polyamide resin, asphalt, paraffin, etc., so the functional properties and environmental properties of moisture-proof paper are greatly affected by moisture-proof drugs. Moisture proof bag paper is used to manufacture paper bags for packaging bulk products, inorganic fertilizers, daily discharged wastes and other goods under high humidity transportation conditions

the production process of green moisture-proof paper-based materials involves the selection of fiber raw materials, the addition process of main chemical additives and the recycling process of target products. Now the performance and application scope of various moisture-proof paper materials are introduced as follows:

1. Moisture proof cellophane

cellophane is also known as "cellophane", also known as transparent paper. It is as transparent and bright as glass. It is a kind of decorative high-grade packaging paper. Since its appearance in 1908, it has been widely used in the fields of food, medicine, sanitary packaging and decoration with its unique non-toxic, tasteless, antistatic and other special properties

cellophane is made of natural fibers such as wood pulp and cotton pulp by adhesive method. It is crisp, transparent, non-toxic and tasteless. Its molecular chain has a wonderful micro permeability, which allows commodities to "breathe" like eggs through the pores on the egg skin, which is very beneficial to the freshness and preservation activity of commodities; Strong resistance to oily, alkaline and organic solvents; It does not generate static electricity and absorb dust. It is suitable for mechanical high-speed packaging and bag making

moisture proof cellophane is made by adding chemicals with moisture-proof properties in the papermaking process, such as polyethylene, polyvinylidene chloride (K-type coating), vinyl acetate copolymer (MST type coating), etc. on the basis of the original material properties, it adds certain moisture-proof properties, which is suitable for the packaging of food, meat and mechanical tools

since moisture-proof cellophane is derived from natural fibers, it can absorb water and be decomposed in garbage, so as not to cause environmental pollution. The processing technology of moisture-proof cellophane coated with polyethylene and K-type is not only less pollution, easy to operate, but also very economical. In view of the potential harm of using plastic as food packaging, the traditional plastic food packaging is facing the fate of being phased out in many developed countries, and the new packaging, moisture-proof cellophane, will show its strong vitality

2. Polyethylene processing paper

polyethylene processing paper is composed of kraft paper and high-density polyethylene or low-density polyethylene. It has the tenacity and firmness of kraft paper. At the same time, it has the superior dielectric property, moisture resistance, good mechanical strength and impact resistance of polyethylene material. It can still maintain softness and chemical stability at low temperature, and can resist the corrosion of acid, alkali, salt solutions and various organic solvents with a certain concentration and temperature. Polyethylene processing paper, especially high-density polyethylene processing paper, is an excellent high-grade moisture-proof packaging material, and its moisture-proof performance is better than PVC processing paper and asphalt paper

for composite moisture-proof materials, because the degree of influence of humidity on the moisture permeability coefficient of each layer of materials is different, that is, the moisture dependence of the moisture permeability coefficient of each layer of materials is different, so when such materials are moisture-proof packaged, it should also be noted that the materials with a large moisture dependence on the moisture permeability coefficient should be placed on the low humidity side, and the materials with a small moisture dependence on the moisture permeability coefficient should be placed on the high humidity side. For example, for polyethylene processing paper, the polyethylene film layer should be placed on the high humidity side

kraft paper in the raw material of polyethylene processing paper is completely pollution-free to the environment, and the polyethylene layer in it is also easy to age in the atmosphere, especially under sunlight. The test shows that it can naturally crack after two years, and the aging degree of low-density polyethylene is faster, so the load on the environment is relatively small

3. Moisture resistant corrugated paperboard

corrugated paperboard is the most widely used paperboard in packaging, especially for commodity packaging, which can be used to replace wooden boxes and metal boxes. Corrugated cardboard is processed from corrugated base paper. First, the base paper is processed into corrugated shape, and then the surface layer is bonded with adhesive from both sides, so that the middle layer of the paperboard is hollow structure. In this way, the corrugated paperboard has higher strength. Its stiffness, hardness, pressure resistance, burst resistance, extensibility and other properties are higher than ordinary paperboard. The cartons made of it are also relatively strong, which is more conducive to the protection of the packaged products. Moisture resistant corrugated board is atomized with paraffin liquid at a temperature of 130 ℃ ~ 180 ℃. In the moisture-resistant paperboard, paraffin wax is formed and the wiring is accurate; The quality of the corrugated board is 30% - 45%. This kind of corrugated board has high moisture resistance, and its strength is much higher than that of the non impregnated board

in recent years, due to the development of synthetic resin, a calcium plastic 7 The pendulum has an obstacle corrugated cardboard in the lifting process, which can overcome the shortcomings of some original corrugated cardboard. It has the characteristics of moisture-proof, rain proof, high strength, and rich sources of materials, which are more and more widely used

calcium plastic corrugated board refers to plastic paper with calcified filler. It is a kind of plastic packaging material, rather than paper packaging material. Compared with cowhide corrugated paper, it is used to be called cardboard

both Kraft corrugated paper and calcium plastic corrugated board have the characteristics of light weight, high mechanical strength and good moisture resistance. The folding property of the cartons made is good. The main performance indicators of the products (such as breaking strength, durability, breaking strain, modulus, etc.) can be confirmed through experiments. The storage space is small, the transportation cost is low, and it can be reused many times after use. It is easy to recycle. It is an excellent green substitute packaging for transportation

4. Kraft linerboard

Kraft linerboard is also known as vermicelli or kraft paperboard. In foreign countries, 100% natural color Kraft wood pulp is generally used for making kraft board, and a few use natural color Kraft wood pulp as vermicelli, while waste paper pulp is used as the core and bottom layer. Due to the lack of wood resources in China, 40% - 50% wood pulp is used for vermicelli, and one or two mixed Taiwan pulps such as wheat straw pulp, straw pulp, awn straw pulp, bagasse pulp and waste paper pulp are used as the core and bottom layer, and 100N bamboo pulp is developed, Or 60%~70% bamboo pulp and straw pulp or waste pulp, or 20% wood pulp and cotton straw pulp and Kenaf straw pulp are copied, and finally made into Kraft linerboard through sizing and calendering. Its sizing degree is more than 0.75mm, so it has strong water resistance and moisture resistance

Kraft linerboard is a high-grade paperboard for transportation and packaging. It is more tough and firm than ordinary cartons, has extremely high compressive strength, puncture strength and folding resistance, and has the characteristics of good moisture resistance and good appearance quality. It is mainly used to manufacture foreign trade packaging cartons and domestic high-end commodity packaging cartons

in recent years, due to the gradual improvement of the requirements for packaging quality, the packaging cartons of some high-end goods (such as high-end alcohol, beverages, etc.) have gradually replaced the original gray background white board and natural color kraft paper with white kraft paper produced by all wood pulp. The development speed is very fast and the demand is very large. Therefore, moisture-proof white faced Kraft linerboard required by moisture-proof packaging also came into being

the base pulp of the raw material for the production of white kraft paperboard adopts the self-produced natural color sulfate coniferous wood pulp and some purchased wood pulp; The face pulp uses the self-produced full bleached sulfate coniferous wood pulp. The ratio of base slurry to surface slurry is 7:3. In the actual production process, the ratio of slurry can be adjusted according to different requirements

5. Moisture proof flat bonded paperboard

flat bonded paperboard is a multi-layer material tightly bonded by two or more flat layers of paperboard. Flat bonded paperboard can be bonded to the outer and inner layers with different materials, usually using paperboard with lower performance. Cardboard is bonded with silica gel. The number of layers of cardboard depends on the requirements of cardboard boxes, and the properties of raw materials and their strength indicators should be taken into account. Compared with corrugated board, flat bonded board has higher strength index and higher pressure resistance

moisture proof flat bonded paperboard is made of moisture-proof raw materials and moisture-proof glue, which can achieve certain moisture-proof capacity

some moisture-proof flat bonded paperboards are obtained by polyethylene treatment on the surface. Usually, the polyethylene coating is added to the outer layer of the rolled cardboard by spraying in advance, and then it is pressed with the cardboard on the bonding machine. In this way, the flat bonded cardboard with one or both sides of the polyethylene coating can be obtained. Due to the impermeability of the polyethylene layer, the adhesive with the least water content must be used for bonding with the paperboard, such as latex, polyacetic acid 4, what kind of fixture vinyl ester lotion and hot-melt adhesive are recommended for customers. In order to improve the moisture resistance of dry bonded paperboard, beeswax mixture can also be coated on its outer surface. These auxiliary agents are non-toxic materials, which will not cause chemical pollution

moisture proof flat bonded cardboard packaging boxes are mainly used for products requiring sufficient strength in the packaging box under high humidity conditions, such as food, vegetables, explosives, various spare parts, hardware products, etc., as well as transfer packaging boxes for products transported in cold areas

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