Advantages and disadvantages of different kinds of plastic packaging bags

There are many kinds of plastic packaging bags. Dongguan time Marriott Packaging Co., Ltd. summarized the following several kinds, and analyzed their advantages and disadvantages. The commonly used plastics are mainly polyethylene and polypropylene. The advantages and disadvantages of polystyrene, PVC, polyurethane and phenolic resin are analyzed as follows:

1. Polyethylene (PE)
Polyethylene is a high molecular polymer of ethylene and a thermoplastic. According to its industrial production method, there are high pressure, medium pressure and low pressure polymerization methods. Different production methods have different molecular structures, and the properties of products vary with molecular structures Polyethylene is a kind of milky white waxy solid, lighter than water, softer, good water resistance, low temperature resistance, tasteless, non-toxic, poor heat resistance, poor film air tightness, sensitive to UV. Easy to oxidize, aging, large change of heat shrinkage, poor printing performance. According to its density. It can be divided into high-density, medium density, low-density polyethylene and linear low-density polyethylene.

2. Polypropylene (PP)
Polypropylene is a byproduct of petroleum refining, propylene monomer after refining, polymerized under the catalysis of catalyst, and then separated from the polymer. It has a molecular weight of 100000-500000 and a very small density, which is the smallest of known plastics; it is non-toxic, tasteless, transparent, with good mechanical properties, surface strength, anti friction, anti chemical corrosion and moisture resistance; it has a large impact resistance value above room temperature, but a small impact resistance value at low temperature; it is easy to carry static electricity and poor printing performance. Polypropylene has a wide range of raw materials, low price and wide performance adaptability. Widely used in the food industry. It is mainly used to make films and composite films, with good transparency and surface gloss, and can withstand the temperature of 120 ℃; it can be made into packing boxes, blow molded into plastic bottles, and some machine parts can be made by adding some fillers, etc.

3. Polystyrene (PS)
Polystyrene is produced by alkylation of ethylene with benzene under the catalysis of anhydrous alumina to ethylbenzene, and then dehydrogenation. Styrene monomer is polymerized into polystyrene by heating in the water suspension of proper initiator (benzoyl peroxide) and dispersant (polyvinyl alcohol). Polystyrene is a kind of colorless, transparent and non malleable thermoplastic; it is nontoxic, tasteless, odorless, colorable, more permeable than polyethylene, with low hygroscopicity, stable size and good luster; it has good processing performance and low cost; its mechanical property increases with the increase of molecular weight; it has low heat resistance and can not be used in boiling water; it is resistant to low temperature and can bear the low temperature of - 40 ℃ Temperature; good indoor aging resistance; good resistance to alcohol organic solvents, mineral oil, acid and alkali resistance.

Polystyrene is widely used in the food industry because of its superior performance, low price and wide application. It can be made into film and container and widely used in the food industry. Its shrinkage rate can reach 60-70%. It is a good material for making shrink packaging. It has good insulation performance and can make a variety of telecommunication parts. It can also make various machine parts, toys, daily necessities, etc. it can make bubbles by adding foaming agent into polystyrene Foam plastic is a good cushioning packaging material.

4. PVC

Polyoxyethylene is a kind of polyvinyl chloride produced by suspension polymerization or emulsion polymerization of vinyl chloride. It is light brown, transparent, tough, with a density of 1.4g/cm; it has good chemical stability and is not easy to be corroded by acid and alkali; it has good air tightness, water resistance, heat sealing performance, good printability, low production energy consumption and low price; its mechanical strength, wear resistance and pressure resistance are better than that of polyethylene and polypropylene. The main disadvantage is poor thermal stability, easy to decompose when heated, and hydrogen chloride gas is released. Due to the variety and quantity of additives, such as plasticizers and stabilizers, PVC can be made into different products and hard products, such as hard pipes, building materials, etc.; artificial leather, wire and cable insulation layer, plastic floor, etc. Its main function in packaging is to make film, which is divided into soft plasma film, hard film and shrink film. The soft plasma membrane has a soft texture and good heat sealing performance, which is suitable for high-frequency sealing; it has a small tensile strength and a high tear strength; it has poor sliding performance and processing performance. The tensile strength and tear strength of the hard film are large, the texture is hard, and the elongation is small; the moisture permeability is small, the air resistance is good, and the sliding property is good; the printing adaptability is good, but the appropriate ink solvent should be selected; the temperature resistance is poor, and it becomes brittle at low temperature. Shrinkage film is a good heat shrinkable packaging material because of its good transparency, small air permeability, shrinkage during heating, wide range of shrinkage temperature and large shrinkage rate. According to different production processes, it can be divided into dry drawing. Tube drawing and longitudinal and transverse one-way drawing.

5. Polyester (PET)
Polyester is the polycondensation product of terephthalic acid and glycol. Compared with other plastics, polyester has excellent barrier properties, such as good barrier to carbon dioxide, oxygen, water and fragrance; with excellent mechanical properties, it has high strength, compression resistance and impact resistance; good chemical stability, acid and alkali resistance; high transparency, good luster and optical properties; non-toxic, tasteless, in line with food health standards; its structure includes Ester group, so the printing performance is good. Polyester is a unique and widely used packaging material. It can be used to make films, bottles, cans, cups, etc.
It can also be used as a dual-purpose baking tray.

6. Phenolic plastic (PF)
Phenolic resin is formed by condensation of phenols (mainly phenol) and aldehydes (mainly formaldehyde). According to whether the catalyst is acidic or alkaline, the ratio of phenol to formaldehyde is different. Thermoplastic resin or thermosetting resin can be obtained. They can be transformed into each other under suitable conditions. In practice, thermosetting resin is often used. Phenolic resin has good mechanical strength, thermal strength, moisture resistance, corrosion resistance, easy processing and low price. Different phenolic plastics can be made by adding different fillers and curing agents. Various kinds.
After adding lamellar filler to thermosetting resin, laminate can be obtained by laminating. Various phenolic laminates can be prepared by adding foaming agent. When phenolic resin is used for packaging, molding powder is made of phenolic resin mixed with fillers, curing agents and coloring agents, and then molded into bottle cap, machine parts, daily necessities and some packaging containers. Phenolic plastic products have good chemical stability, good heat resistance, high mechanical strength, wear resistance, not easy to deform, but poor elasticity, good electrical insulation, monotonous color, mostly dark red or black. Because its main raw materials are phenol and formaldehyde, which have certain toxicity, it is not suitable for food packaging materials.

7. Polyamide (PA)
Polyamide, commonly known as "nylon", can be obtained by polycondensation of binary acid and binary. Polyamide is nontoxic, colorless and transparent, and has good wear resistance. Strong impact toughness, excellent mechanical properties; good light resistance, light aging resistance; good oil resistance, chemical stability, but not resistant to alcohol, formic acid and phenol; good air tightness; large temperature adaptability, can be used in the range of - 40 ~ 100 degrees; good printing and decoration; large moisture absorption.
Polyamide is widely used in bearing, gear, pump blade, automobile parts, etc. Its application in packaging is mainly soft packaging. The film can also be used in food packaging to make packing belt and rope. Its firmness is better than polypropylene packing belt.

8. Urea formaldehyde plastic (UF)
Urea formaldehyde plastic is commonly known as "electrical jade". It is made of urea and formaldehyde through polycondensation reaction to obtain urea formaldehyde resin, then add fillers, colorants, lubricants, plasticizers, etc. to process into compression molding powder (Electrical jade powder), and then through heating and molding to form products. It has a high surface hardness, a certain mechanical strength and is not easy to deform, but it is brittle; it is odorless, tasteless, strong in coloring power, bright in color and looks like jade; it has good heat resistance and is not easy to burn; it is acid and alkali resistant, poor in water resistance, high in water absorption and good in electrical insulation. Urea formaldehyde plastics can be made into many kinds of products, such as daily necessities, electrical components, etc. It can be made into beautiful packing box, packing plate, bottle cap, etc. because formaldehyde has certain toxicity, it is not suitable for food packaging. Urea formaldehyde foam can be obtained by adding foaming agent into urea formaldehyde resin and foaming by mechanical means.
It is a widely used cushioning packaging material with light weight, low price, good heat preservation and corrosion resistance.

9. Melamine plastics (me)
Melamine plastics and urea formaldehyde plastics are both amino plastics. It is a kind of thermosetting plastic, which is made of melamine and formaldehyde by polycondensation and resin as the main component, adding fillers, lubricants, colorants, hardeners, etc Melamine plastics are nontoxic, odorless, tasteless and hygienic; they have high mechanical strength, good surface hardness and are not easy to deform; they have smooth surface and feel like porcelain; they have strong impact resistance and pollution resistance; they have good chemical stability. Melamine plastics can be used to make packaging containers of various colors including food packaging.

10. Polyvinyl alcohol (PVA)
Polyvinyl alcohol is the hydrolysate of polyvinyl acetate. It is transparent, nontoxic and tasteless; it has excellent gas resistance, water resistance and oil resistance; it has good chemical stability; it has good printability, no static electricity; it has good mechanical properties. Polyvinyl alcohol can be used in food packaging, which can prevent food from oxidation, discoloration, taste and deterioration, and keep food fresh. It can also pack other products, such as chemical products.

11. Polycarbonate (PC)
Polycarbonate is the general term for the resin with carbonate structure in the molecular chain, usually refers to the polycarbonate of bisphenol a type. It is colorless, transparent, glossy, heat-resistant, cold resistant, and can be used for pressure sterilization, with high mechanical strength. It can be juxtaposed with polyester and nylon; it has excellent impact toughness, and the product is not easy to crack under impact; it has low water absorption, moisture absorption and air permeability; it has good chemical corrosion resistance, and can prevent ultraviolet rays from passing through non-toxic, odorless and tasteless; it has good molding performance, which can be achieved by general molding methods. The precision of formed products is very high. But the heat sealing performance is poor [Page]
Polycarbonate is a kind of engineering plastics with excellent comprehensive properties, which can be used to make all kinds of gears, machine parts, etc.; it can be used to make films for packaging food and other items. When it needs to be sealed, it can be made into composite films to improve the heat sealing performance; it can also be made into various packaging containers.

12. Polyvinylidene chloride (PVDC)
Polyvinylidene chloride is a homopolymer of vinylidene oxide. It is nontoxic, tasteless, transparent and has high mechanical strength. Good toughness, oil resistance and organic dissolving; good heat shrinkage and self adhesion, easy adhesion between films; excellent air tightness and moisture resistance. However, it has poor machinability, poor thermal stability, is not easy to heat seal, and is easy to decompose under the action of ultraviolet.
Poly (vinylidene chloride) (PVDC) is mainly used to make food packaging film, which can be used as sealing packaging and effectively prevent food from moisture absorption. It can be used as the package of sterilized food, because it can be heated and sterilized, and it can also be used as the packaging material for household daily use.

13. Polyurethane (PVP)
Polyurethane, also known as polyurethane, is prepared by the reaction of isocyanate and hydroxyl compounds. Polyurethane is characterized by good wear resistance, excellent low temperature resistance, outstanding oil resistance and chemical corrosion resistance. Polyurethane is mainly processed into foam plastics, and different foam plastics can be obtained by changing raw materials and proportioning. Soft products, with good toughness, good elasticity and oil resistance, are the main varieties of polyurethane foam plastics. They are widely used in cushioning materials such as cushions in packaging. Hard products are heat-resistant, cold resistant, heat-insulating, with excellent shock resistance, widely used in the packaging of precision instruments and meters. The production of polyurethane foam is simple. Easy to operate, low cost, good shock resistance, can be made at room temperature, especially through field foaming, which brings great convenience to packaging.