Section 2 Product Packaging Materials, Types, and Characteristics
Packaging material refers to the general term used for the manufacture of packaging containers and packaging and transportation, packaging and decoration, packaging and printing, packaging auxiliary materials, and packaging related materials. Packaging materials generally include the main packaging materials and auxiliary packaging materials, commonly used paper, metal, wood, plastic, textiles, ceramics, glass, grass, bamboo, rattan, wicker, etc. Among them, plastic and metal materials are the most complex.
Packaging materials occupy an important position in the entire packaging industry and are an important basis for developing packaging technology, improving packaging quality and reducing packaging costs. Therefore, to understand the performance, application scope and development trend of packaging materials, reasonably select packaging materials, expand the source of packaging materials, adopt new packaging materials and new processing technologies, create new packaging containers and packaging techniques, and improve the level and law of packaging technology. Both have important and far-reaching significance.
First, the performance of packaging materials
From the perspective of modern packaging functions, packaging materials should have the following aspects:
(I) Protection performance
Packaging materials should have a certain mechanical strength, adapt to temperature changes, can moisture, waterproof, corrosion, UV penetration, heat, cold, light, oil, etc., and their own should be no smell, non-toxic, odorless, can protect the interior The quality is good.
(II) Operational performance
Packaging materials should have a certain degree of rigidity, heat sealing and anti-static properties, have a certain degree of finish and plasticity, weldability, easy opening, easy processing, easy filling, easy to divide and so on, suitable for automatic packaging machinery operation, high production efficiency .
(III) Added value performance
Packaging adds value to goods, and good packaging increases the value and use of goods. In particular, as a sales and packaging material, it is required to have good transparency and surface gloss, so that the appearance and color of the model are beautiful, and display effects are produced so as to increase the value of the goods and the desire of the consumers to purchase.
(four) to facilitate the use of performance
No matter what kind of material is used to package goods, the basic requirement is to facilitate the opening and extraction of the contents, to facilitate re-closed, open the performance is good, not easy to break and damage.
(E) Reduce cost performance
The backward packaging not only increases the cost but also fails to achieve the desired effect, so it is undesirable. When selecting the packaging materials and methods for practical applications, in addition to considering the above requirements, it is also necessary to consider the cost savings of packaging materials, packaging machinery and equipment, labor costs, etc., use of the most suitable materials, and the most reasonable packaging method. best effect.
(6) Adaptability to the nature of the commodity
Product packaging must be compatible with the nature of the product. Some silk heads, for example, are met directly with customers at the store, and some are processed or finished into the factory. Their packaging should be different. The former should be made more elaborate to highlight the quality characteristics of silk and the latter requires Flat goods do not wrinkle, easy to open, to facilitate the factory processing. Another example is polyurethane polyurethane foam liner technology, is a relatively new scientific and technological achievements, use it to increase the value of goods, to protect the safety of goods, but the use of such packaging needs to be molded one by one, high cost and time, it is only used for packaging Valuable carvings and precious arts and crafts such as antique porcelain, while general crafts such as wood carvings and ornaments are made of polyethylene plastic and bubble wrap.
Second, the main packaging material characteristics and applications
(a) Paper and cardboard
Paper and paperboard are pillars of traditional packaging materials. They have a large amount of consumption and a wide range of applications. Their output value accounts for about 45% of the total packaging value. Paper and cardboard have the following characteristics:
1. With suitable strength, impact resistance and rub resistance.
2. Good sealing, easy to clean.
3. Has excellent formability and folding, easy to use a variety of processing methods, should be mechanized, automated packaging production.
4. Has the best printability, easy to introduce and beautify the goods.
5. The lower price and lighter weight can reduce packaging costs and transportation costs. Easy to handle after use, recyclable reuse and regeneration, no environmental pollution, and resource conservation.
Paper and paperboard also have some fatal weaknesses, such as difficulty in sealing, decreased fastness after moisture, and poor airtightness, moisture resistance, and transparency, which makes them subject to certain restrictions in packaging applications.
Paper and cardboard made of large packaging containers are mainly cartons, cartons, paper drums, paper bags, paper cans, paper cups, paper trays, etc., are widely used in transport packaging packaging sales. In paper-based packaging containers, corrugated cartons are used in the largest amount, and their proportion accounts for more than 50%. In transport packaging, corrugated cartons are replacing traditional wooden boxes and are widely used for packaging of general merchandise, household appliances, clothing and footwear, fruits, and vegetables. At present, corrugated boxes are being developed in the direction of standardization of specifications, specialization of functions, reduction of weight, and improvement of compressive strength. Except for corrugated cartons, other paper packaging containers are mostly used for sales packaging, such as packaging for food, medicines, clothing, toys and other daily necessities. The carton can be made into a window type, a swing cover type, a drawer type, a fitting type, etc., and the surface is decorated to have a better exhibition effect. The drums are strong and durable and can hold granular, blocky, and powdered goods. Paper bags are used in a wide variety of applications. Paper cups, paper trays, and paper cans are disposable food packaging and are widely used because they are inexpensive, lightweight, convenient, and hygienic. Paper cups are generally small containers for cold drinks. The paper trays are frozen food packages that can be frozen and heated in a microwave oven. The paper cans are made of high-density cardboard with a cylindrical, conical shape and are generally coated to prevent leakage. They are used to hold beverages. Pure paper cans have been replaced by composite cans consisting of paper, plastic and aluminum foil. Pulp moulded packaging is a cushioning material made by direct molding and drying of paper pulp, such as moulded egg trays, used for egg packaging, which can greatly reduce the breakage rate during transport.
(B) Packaging plastics and their characteristics`
Plastics are emerging materials that flourished in this century, which has revolutionized the packaging of modern commodities, changing the entire face of commodity packaging. The proportion of plastics in the entire packaging material is second only to paper and cardboard. The amount of plastic used for packaging accounts for 1/4 of the total plastic consumption. In many respects, it has replaced or gradually replaced traditional packaging materials. Such as making woven bags and tying ropes instead of cotton and linen; making packaging bags, packaging boxes, and packaging barrels instead of metal; making bottles and cans instead of glass; making various plastic bags instead of paper; making turnover containers and calcium plastic boxes instead Wood; made of a variety of foam instead of traditional buffer materials. Plastics include flexible films, fiber materials, and rigid molding materials. The basic features are:
1. Excellent physical and mechanical properties, with a given strength and elasticity, resistance to folding, abrasion, impact, vibration, pressure, moisture, water, and gas barrier
2. Good chemical stability, acid and alkali resistance, grease resistance, chemical resistance, corrosion resistance, light resistance, etc.
3. The proportion is small, which is 1/2 of glass's specific gravity. It is one-fifth of that of steel. It belongs to lightweight materials. Therefore, the finished packaging container is lightweight and adapts to the development needs of lightweight packaging.
4. The process of forming is simple and it is easy to manufacture various packaging materials and packaging containers.
5. Suitable for a variety of packaging new technologies, such as vacuum, inflatable, stretching, shrinking, body, composite and so on.
6. With excellent transparency, surface gloss, printability and decorative, it provides good conditions for packaging and decoration.
Plastics also have some disadvantages as packaging: strength is inferior to steel; heat resistance is not as good as glass; external factors are prone to ageing for a long period of time; some plastics soften at high temperatures, become brittle at low temperatures, and decrease in strength; some plastic tapes Odor odor, some harmful ingredients may infiltrate the contents; easy to cause static electricity and cause pollution; improper disposal of plastic packaging waste will cause environmental pollution. Therefore, pay attention to the above issues when selecting plastic packaging materials.
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(c) Characteristics of several important plastic materials for packaging
1. Polyethylene plastic (PE).
It is a general-purpose thermoplastic plastic with light weight, softness, non-brittleness, odorless, tasteless, non-toxic, strong chemical stability and good insulation. Polyethylene plastics can be classified into high density, medium density and low density according to density. High-density polyethylene is resistant to impact, but its elasticity and transparency are inferior to those of low-density polyethylene. Therefore, it is more suitable for manufacturing large vacuum packaging containers and heavy packaging bags, as well as various barrels, bottles, cups, pots, boxes and the like. The mechanical properties, electrical insulation, and corrosion resistance of medium-density polyethylene are higher than those of low-density polyethylene. Generally, they are not used as packaging materials. Low-density polyethylene has good impact strength, transparency, softness, air permeability and moisture permeability, but its tensile strength and hardness are poor. It is widely used in the manufacture of films and packaging bags, and often combined with other materials to produce various composites. Packaging Materials. In addition, polyethylene plastics can also be used to make hoses, foams and coating materials, materials, and the like. Because polyethylene has excellent performance and is non-toxic, it is often used as a packaging for drugs and foods.
2. Polyvinyl chloride (PVC).
Belong to general-purpose thermoplastics, generally can be divided into two kinds of soft and hard. PVC has strong plasticity, good decoration, printing performance and relatively high light transmittance, good chemical stability and mechanical properties. Lightweight polyvinyl chloride is mostly used in the manufacture of films and various packaging bags; rigid polyvinyl chloride can be made into various bottles, cups, plates, boxes and other containers, but it is not suitable for packaging foods.
3. Polypropylene (PP).
Is a tough plastic, the lightest of a variety of plastic. Its tasteless, non-toxic, mechanical properties than polyethylene, impact resistance, wear resistance, corrosion resistance and insulation, and has good tensile strength, heat resistance and gas barrier properties. Polypropylene plastics can be used for blow molding and vacuum forming to manufacture various bottles, cups, plates, boxes, packaging films, woven bags, packing belts, etc., and have the advantages of corrosion resistance, mildew resistance, light weight, folding resistance, and low price. . Biaxially oriented polypropylene film can be used instead of cellophane to package candy and food at a lower cost than cellophane. Polypropylene plastics are not suitable for aroma-rich commercial packaging and are not suitable for long-term packaging of vegetable oils and mineral oils.
4. Polystyrene plastic (PS).
It belongs to rigid plastics, which has rigidity, good printing performance, shiny surface, strong chemical resistance, non-toxic and odorless, and is a good packaging material with light weight and high strength. In the packaging industry, modified polystyrene is used for injection molding to manufacture various barrels, deep cups, plates, boxes and other packaging containers. It is also made of stretched polystyrene and foamed polystyrene in shallow cups, trays, boxes, etc. Container suitable for holding foods, acids or bases. Foams made from polystyrene and foaming agents can be used as cushioning packaging materials for instruments, meters, televisions and high-end electrical products.
5. Polyamide (PA).
Both synthetic fibers and plastics, often referred to as nylon. It has good impact toughness and excellent wear resistance; high tensile strength, hardness and fatigue strength; light resistance, vapor heating resistance and air tightness; and good printing and decorative properties; non-toxic. Nylon is mainly used for flexible packaging, especially in food packaging applications. For example, nylon 6 film is widely used for packaging of oils and fats, frozen foods, vacuum packaged foods, retort pouches, and dairy products. In addition, it can also be used to make straps and ropes, which are more rugged than polystyrene straps.
6. Polyvinyl alcohol (PVA).
Polyvinyl alcohol is a preferred packaging material for water soluble products. Heat-treated polyvinyl alcohol has the advantages of water resistance, fragrance protection, oil resistance, and low air permeability. The film has remarkable effects on maintaining food freshness, preventing oxidative discoloration, deodorization, and deterioration; it is also suitable for packaging of some chemical products. .