Plastic bags are generally made of PE (polyethylene) materials by blown film. Soft-tagged is a low-density (commonly known as high-pressure) polyethylene, and a somewhat brittle, high-density (high-pressure) polyethylene. High-strength polyethylene with a metallocene polyethylene material is generally required for high strength packaging of milk and cosmetics. Highly transparent plastic bags such as packaged bread are made of PP (polypropylene) material, and because it is made by biaxial stretching, it is referred to as BOPP film bag. There is also a small amount of PVC (polyvinyl chloride) film, but due to its large amount of additives, it has an impact on human health and is being widely replaced by polyethylene bags.
Plastic bag processing is relatively simple from the surface point of view, only need to configure a blow molding machine, a bag making machine or manual bag making, printing needs to be on the printing press, you said the three raw materials are commonly used materials, the most The key is the sales volume. The price is generally calculated according to KG. The volume can be calculated according to the length, width and thickness of the plastic bag. The proportion of polyethylene is generally about one, the exact point can be calculated by 0.93 to calculate the weight, and then multiplied by raw materials. Unit price can
According to the processing technology, plastic bags are divided into: edge sealing bags, bottom sealing bags, middle sealing bags, and three-side sealing. Need four different machines.
Materials, OPP, PE, POF, composite film, etc.
The market price of polyethylene pellets, the main production material for plastic bags, is 1.4 or 15,000 yuan/ton (market price).
Degradable masterbatch from 5,000 yuan or 6000/ton (market price
Refers to polypropylene, pe refers to polyethylene, and pvc refers to polyvinyl chloride. Commonly used plastic bag materials are mostly pe, pvc, of which pe is mostly used for food; pvc because of its cheap, more use. Retail stores use pvc bags for non-food. It is strongly recommended not to use pvc to hold food and it will precipitate toxic substances
Plastic composite bags, aluminum-plastic composite bags, invisible anti-counterfeit packaging products, all kinds of ice cream bags, cups, all kinds of food bags, boxes, cigarettes inside and outside the box, pharmaceutical packaging bags
Vacuum packaging bags, cooking bags, stand bags, anti-counterfeit packaging products
OPP bags for foods; automatic bags for sugar packets; veterinary bags; food vacuum bags;
Now we use disposable plastic cups and plastic bags, the main raw materials are polyester, polyethylene, polypropylene, polystyrene, polyvinyl chloride, etc. Among them, polyethylene, polypropylene is a safe plastic, can Used to hold food. Most PVC plastic bags are toxic and cannot pack food. Because the unpolymerized vinyl chloride monomer in the polyvinyl chloride resin will be toxic to the human body, and in the process of processing the polyvinyl chloride resin into a plastic bag, some plasticizers, pigments and other toxic auxiliary materials must be added. The main ingredient of the stabilizer is lead stearate, which is also toxic. This lead salt is easily precipitated, and once it enters the body, it can cause accumulated lead poisoning. These toxic substances are eaten together with food and have a good effect on human health.
Refers to polypropylene, pe refers to polyethylene, and pvc refers to polyvinyl chloride. Commonly used plastic bag materials are mostly pe, pvc, of which pe is mostly used for food; pvc because of its cheap, more use. Retail stores use pvc bags for non-food. It is strongly recommended not to use pvc to hold food and it will precipitate toxic substances
Plastic packaging film material
The share of plastic packaging and plastic packaging products in the market is increasing, especially composite plastic flexible packaging, has been widely used in food, medicine, chemical and other fields, and in which the largest proportion of food packaging, such as beverage packaging , frozen food packaging, cooking food packaging, fast food packaging, etc., these products have brought great convenience to people's lives.
Several common films
Biaxially oriented polypropylene film (BOPP)
The biaxially oriented polypropylene film is formed by coextruding polypropylene particles to form a sheet, and then stretching the sheet in both directions. Due to the orientation of the stretching molecules, the film has good physical stability, mechanical strength and airtightness, high transparency and gloss, tough wear resistance, and is currently the most widely used printing film, generally having a thickness of 20 to 40 μm, the most widely used is 20 μm. The main disadvantage of biaxially oriented polypropylene film is poor heat sealability, so it is generally used as the outer film of composite film. If it is compounded with polyethylene film, it is ideal for moisture resistance, transparency, strength, stiffness and printability. Contains dry foods. Since the biaxially oriented polypropylene film has a non-polar surface, a high degree of crystallinity, and a low free surface energy, its printing performance is poor, adhesion to ink and adhesive is poor, and the surface needs to be printed before printing and compounding. deal with.
, low density polyethylene film (LDPE)
Low-density polyethylene film is generally made by two processes: blow molding and casting. The thickness of the cast polyethylene film is uniform, but it is rarely used because of its high price. The blow-molded polyethylene film is blown from a blow molding machine with blow-molding grade PE particles. The cost is low, so it is the most widely used. Low-density polyethylene film is a translucent, glossy, soft texture film, with excellent chemical stability, heat sealing, water resistance and moisture resistance, freeze-resistant, can be boiled. Its main disadvantage is its poor barrier to oxygen, which is commonly used in the inner film of composite flexible packaging materials. It is also the most widely used and the largest amount of plastic packaging film, accounting for about 403 of the consumption of plastic packaging film.
Because the polyethylene molecule does not contain polar groups, and the degree of crystallinity is high and the surface free energy is low, the printing performance of the film is poor, and the adhesion to the ink and the adhesive is poor, so it is required before printing and compounding. Perform surface treatment.
Polyester film (PET)
Polyester film is made of polyethylene terephthalate as a raw material, made by extrusion method thick film, and then made of biaxially stretched film material. It is a colorless, transparent, glossy film with excellent mechanical properties, high rigidity, hardness and toughness, puncture resistance, friction resistance, high temperature resistance and low temperature resistance, chemical resistance, oil resistance, airtightness, and fragrance retention Good is one of the commonly used barrier composite film substrates. However, the price of polyester film is relatively high, and the general thickness is 12mm. It is commonly used as outer layer material for cooking and packaging, and the printing property is better.
, nylon film (PA)
Nylon film is a very tough film with good transparency, good gloss, high tensile strength and tensile strength, and good heat resistance, cold resistance, oil resistance and organic solvent resistance. Excellent abrasion resistance and puncture resistance, relatively soft, excellent oxygen barrier, but poor barrier to water vapor, greater moisture absorption, moisture permeability, poor heat sealability, suitable for packaging hard goods, such as greasy Sex foods, meat products, fried foods, vacuum packaged foods, steamed foods, etc.
Cast Polypropylene Film (CPP)
Cast polypropylene film is polypropylene film produced by casting process, and can be divided into ordinary CPP and cooking grade CPP. It has excellent transparency, uniform thickness, and uniform longitudinal and transverse performance. It is generally used as a composite film. Layer material. The thickness of the ordinary CPP film is generally between 25 and 50 μm. After being compounded with the OPP, the transparency is better, the surface is brighter, and the hand feels firm. This kind of material is used for the general gift bag. This film also has good heat sealability. The thickness of cooking-grade CPP film is generally between 60 and 80 μm. It can withstand 121°C and 30 min high-temperature cooking. It has good oil resistance and airtightness, and has a high heat seal strength. The average inner layer of meat packaging is Cooking grade CPP film was used.
, aluminized film
At present, the most widely used aluminum plating films are polyester aluminum film (VMPET) and CPP aluminum film (VMCPP). The aluminized film has both the characteristics of a plastic film and metal characteristics. The role of aluminum on the surface of the film is to block light and prevent ultraviolet radiation, which not only prolongs the shelf life of the contents, but also improves the brightness of the film, replacing aluminum foil to a certain extent, and also has low cost, attractive appearance, and good barrier properties. The application of aluminized film in composite packaging is very extensive. At present, it is mainly applied to dry and puffed food packaging such as biscuits and packaging of some medicines and cosmetics.
This information comes from China Packaging Bags Trading Network