Overview of the hottest composite packaging materi

Overview of composite packaging materials (II)

III. application of composite packaging materials 1 in food packaging

at present, composite packaging materials are used most in the food industry. For example, aluminum foil/wax/tissue paper (for chewing gum packaging), aluminum foil/tissue paper/wax (for chocolate packaging), aluminum foil/oil proof adhesive/parchment (for butter, cheese packaging), etc. Generally speaking, composite packaging materials are waterproof, oil-resistant, heat-resistant and other characteristics, which are widely used. Generally, it can be used for: (1) the packaging of solid food, such as instant noodles, all kinds of milk candy, cereal, chocolate, laver, tea, all kinds of dried fruits (such as raisins), puffed food; (2) Liquid food, such as milk, sweet wine, fruit juice, soy sauce, vinegar and other packaging; (3) Fresh food, used for packaging raw fish, fresh meat, eggs, etc

examples of the application of composite packaging materials in beverages, such as the famous "Tetra Pak" launched by the Swedish company, which has two types: brick type and roof type, and the volume of cartons is 250 ml, 500 ml and 1000 ml. There are seven layers of composite paper used, namely low density polyethylene (LDPE)/aniline printing surface/composite base paper (Quantitative 175 ~ 180g)/ldpe/aluminum foil (thickness 7 ~ 9 microns)/surlym/ldpe. Such a multi-layer structure can prevent air infiltration, water leakage and heat insulation, and ensure that the contents of the package are fresh within the shelf life

2 in terms of drug packaging, western medicine is divided into tablets, powders, injections, etc. in the past, their packaging was mainly made of plastic and glass. Later, blister packaging materials have achieved great development. The production cost of using this kind of packaging is low, the processing speed is fast, and the performance of protecting drugs is good, which is both economical and convenient for patients. According to preliminary statistics, it is now growing at an annual rate of 8%. Blister packaging actually belongs to one of the applications of composite packaging materials. The refining result of aluminum foil is aluminum plated film (VAM). Polyethylene (PE)/vam/paper/pe is used to package drugs. Its advantages are: reducing volume, good barrier, preventing moisture deterioration, and extending the validity period. At present, there are many composite packaging materials used in this field, such as pvdc/vam/pp (polypropylene), pet (polyester film)/vam/paper/pe, etc. Traditional Chinese medicines include pills, powders, ointments, pills, etc. traditional packaging can no longer adapt to the new situation. It is expected that composite packaging materials can show their skills. Unfortunately, few relevant research topics have been reported

3 in terms of military packaging

military products cover a wide range, from the sky to the earth, from the top of the mountain to the bottom of the sea, from launching to eating and wearing, and all materials required by military departments are military products. In the situation of modern and high-tech war, with the change of the military's "five in one" (land, sea and air, all-weather, all-round, in-depth, optical, magnetic and electrical) combat system, logistics support has a more important strategic and operational position. Therefore, we should pay more attention to the packaging of military products, and it is particularly important to minimize the damage and pollution of military products

the protective packaging of military products should not only stay on the basic functions of moisture-proof, mildew proof and rust proof, but also need to strengthen its efforts in anti magnetism, anti explosion, anti biochemical, anti microwave and other aspects. It seems to be of great practical significance to develop and use new composite packaging materials

4 one of the typical examples of composite packaging materials commonly used in sundry packaging is a kind of label paper, or self-adhesive label, also known as "instant sticker" (JAC). It has been widely used on shelves in many optional (super) markets. On this kind of composite trademark paper, various exquisite patterns can be printed. When using, just peel off the coated paper of the surface layer (including the adhesive layer) and paste it on the commodity. The structure of composite trademark paper is usually divided into five layers: the first layer (surface layer) is coated paper, which is printed with color patterns and Related words, prices, etc; The second layer is adhesive layer (self-adhesive), which generally adopts acrylic resin glue; The third layer is the anti adhesion layer (coated with silicone rubber and polymethylethoxysilane); The fourth layer is the reinforcing layer (coated with high-pressure polyethylene, paraffin, PVC, etc.); The fifth layer (bottom layer) is colored kraft paper or parchment for carrying surface paper. The total weight (5 layers) of composite trademark paper is more than 180 g/m2, and this paper is required to be "peeled well and adhered firmly", which saves time and is convenient to use

IV. processing methods of composite packaging materials

there are four main processing methods of composite packaging materials:

(1) dry compounding, which is the simplest compounding method. This method is to coat a layer of adhesive on the first layer of substrate or film, dry it, and then add the second layer of substrate or film, which is processed by hot pressing roller to make it composite. If the third layer of substrate or film is required, it can be repeated by coating another layer of adhesive. The advantage of this compound method is that it is simple and easy to operate. However, the quality of finished products can only be ensured by selecting the appropriate adhesive Generally speaking, adhesives with solvent properties, such as polyurethane, vinyl acetate resin, natural rubber emulsion, vinyl chloride vinyl acetate copolymer, etc. Polyurethane composite film has good elasticity, high heat resistance and good heat sealing performance, so it can be used to bond cooking bags without peeling in a wide range of temperature and humidity

(2) wet compounding, which is a commonly used compounding method. This method is to brush a layer of water-soluble adhesive on the surface of the substrate first, and then stick another substrate or film after it is wetted. Press it by pressing roller, and then heat and dry it. The advantages of this method are low cost, relatively economic, large-scale processing and no solvent pollution. The adhesives used are relatively cheap, such as aqueous solutions of starch, polyvinyl alcohol, sodium silicate, etc. In addition, there are nitrile rubber, styrene butadiene rubber, polyisobutylene and so on. Because the adhesive used for wet compounding is water-soluble, at least one layer of its substrate should be paper, dry paper or cellophane, and it cannot be soaked by water and cause deformation. The speed of the press roll is generally 160 m/min, up to 300 m/min. Wet method cannot be used for lamination between films

(3) hot melt compounding mainly uses the formula of hot melt coating and temperature to control its viscosity. The hot melt coating contains several high molecular compounds, resins, waxes and other components (referred to as hot melt for short), and their maximum temperature does not exceed 175 ℃. Because the hot-melt coating can be flexibly mixed, and good adhesion can be obtained. Moreover, it does not need to be processed and dried and does not use organic solvents, so it does not emit odor pollution, easy to cause fire and other hazards. The hot melt method can adopt the following three processing methods to complete the compounding operation: the first is curtain flow compounding, which is to pump the hot melt from the storage tank to the "die head" (the seam width is less than 0.5mm), form a uniform curtain flow of hot melt through air processing, and then compound with the substrate, which can be carried out many times. The second is seam mold compounding. The hot melt is sprayed directly onto the back roll (the surface is covered with substrate) through the "die" of the seam mold, and the coating amount is controlled according to the purpose of the material. The third is roll compounding. The roll coater used is roughly the same as the coater in the paper industry. They include reversing roller, gravure roller, transfer roller, impregnation tank, etc. Apply the coating amount of 5 ~ 300 g/m2 at the speed of 50 ~ 300 m/min

(4) compound by extrusion method. This method does not use adhesives, but one of the processing materials must be plastic (resin), otherwise it is difficult to form. The compounding process is as follows: the resin (such as polyethylene particles) and other materials are fed into the extruder, and the resin is melted and mixed to obtain uniform materials through the rotation and heating of the screw in the extruder. Under the action of high pressure, the material is extruded through the die to form a film. This film is stretched to the specified thickness, and then combined with other substrates in the pressing zone composed of metal cooling roller and rubber coating roller

v. the application of composite packaging materials

1 the demand is large

from the trend of global economic development, the demand for composite packaging materials can be said to be increasing day by day. With the development of foreign economic undertakings, the number of export commodities has increased significantly, because the packaging requirements are increasingly strict in order to be in line with "international standards". Therefore, the demand for composite packaging materials can play a protective role, and the collision of sensors is increasing. When the oil collector is unloaded in the domestic market, people are not satisfied with the "old routine" because of the need of building a well-off society, and more attention is paid to the "part" of packaging in economic consumption. Therefore, manufacturers and businesses are very concerned about improving commodity packaging, and using more composite packaging materials has been put on the agenda. At present, food and drug packaging are the most used composite packaging materials in China, while other departments are relatively few. According to the requirements of economically developed countries for composite packaging materials, it should account for at least 30% of the total amount of measuring materials for the ductility of packaging materials, which is far from us

2 insufficient processing technology ability

generally speaking, we have relatively mature experience in the processing of traditional packaging materials. There are still many technical gaps in the processing of composite packaging materials. However, as long as there is market demand and capital investment, the ability can be enriched and improved

3 there are few supporting special devices

in addition to general mechanical equipment, there should also be special devices to process composite packaging materials. However, the application of special devices is narrow, and they also need to be designed, processed and debugged according to the relevant composite packaging materials, which obviously costs a lot of money and energy. However, if the device is not large but small, this problem is easier to solve

4 the research level needs to be improved

it should be noted that China's packaging industry started late, "congenitally deficient, but the day after tomorrow is hard". As packaging is a comprehensive practical science, it involves a wide range of disciplines. Composite packaging materials is a new discipline, and the lack of researchers, especially the lack of discipline leaders, is a practical problem

modern packaging includes the knowledge of 15 disciplines such as design, materials, manufacturing, decoration, printing, machinery and logistics, and has links with more than 40 departments. Therefore, excellent packaging technology research talents must undergo special and strict training and long-term work practice in order to stand out

VI. development direction of composite packaging materials

what is the future trend of composite packaging materials? This is one of the issues of common concern in the industry

first of all, high and new technology should be introduced. Packaging industry is one of China's traditional industries. In the open world market, packaging industry, like other industries, faces fierce competition. To ensure stable and sustainable development, it is urgent to use high and new technology. This constitutes the era background and development impetus for the adoption of high and new technology. In recent years, computers, microelectronics, nano materials and bioengineering have been applied in the packaging industry. These are undoubtedly very beneficial to the development of composite packaging materials

next is how to save natural resources and protect the ecological environment. Packaging industry is essentially a material industry. It consumes materials and uses materials, while composite packaging materials use more materials. It is said that based on the savings of traditional packaging materials, wood can be used for about 100 years, and oil (raw material of plastic)