Stretch film is a type of plastic product characterized by stretching. Firstly, it is mainly divided into two categories according to raw materials, one is PVC stretch film and the other is PE stretch film.
PVC is polyethylene. PVC stretch film is a special kind of stretch film, which is commonly used to wrap wires and cables, various finishing rollers, machinery and equipment, hardware accessories, hoses, steel pipes, furniture, building decoration materials, travel sports shoes, non-woven fabrics and another special-shaped product packaging.PVC stretch film is self-adhesive due to electrostatic adsorption, and will not cause secondary pollution to the packaged products.
PE is polyethylene, which is a transparent thermoplastic. There are three commonly used types of PE, namely: LDPE, HDPE, and LLDPE. The monomers of the three polyethylene types are the same, but the process conditions used in the synthesis of this polyethylene are different. Therefore, three different polyethylene varieties are produced, and the properties of the three materials are very different.PE stretch film is a kind of material with good toughness, which is not easy to crush with an ordinary plastic crusher.
Because the PE stretch film is soft and tough, it is not easy to chop, not to mention the high temperature of the tool at high speed, which will melt the LDPE and adhere to the blade. For the granulation of PE, it can be directly placed in strips into the feeding port of the extruder, and the PE stretch film can be dragged into the barrel by the shear force of the screw to heat, melt, and squeeze out the granulation. The first-grade material recycled from PE can still be blown film, used in non-food and pharmaceutical packaging, and is also widely used in the production of Oxford leather and tarpaulin, with a bright future.
Secondly, if it is used in accordance with the method, it can be divided into hand-use stretch film, machine-use pre-stretched stretch film and machine-use stretch-resistant stretch film.
Hand-used stretch film: Manual method is used. It is not recommended to pack more precise parts because of its poor quality. The weight of a roll is about 4kg.
Pre-stretched stretch film for machine use: it is packaged in a mechanical form, and when the packaging reaches a certain proportion, it can be wound directly on the desired object. Relying on its good resilience, the items are well wrapped, with good ductility and good penetration resistance.
Machine-made drag-resistant stretch film: Like machine-made pre-stretched stretch film, it is also packaged in the form of machinery, and the stretch film is packaged through the movement of the goods. This method has high requirements for the ductility of its stretch film, the packaging quality is better, and the weight of a roll is about 15kg.
Third: by weight
Stretch films are large and small, and can be divided into three categories: Mini, hand, and machine; the Mini version is generally 0.3~1kg. This size is suitable for packing relatively small items. Hand films are generally 1.5~4kg. This kind is more suitable for packing larger and medium-sized items. Most of the last type of machine film is more than 10kg. Most of the stretch films of this specification are used by factory machinery to pack large-scale goods.
Fourth: Divide by color
There are many colors of stretch films. If they are divided into common ones, they can be divided into transparent, black, and other colors. Among them, transparent and black are the most widely used. Black and other colors do not add pigments in the production process but add color masterbatch. The stretch film with true quality assurance is odorless and non-toxic, so you can use it with confidence.
There are also some special stretch films, such as breathable stretch films: it is reinforced breathable stretch films with fishing net-like breathing holes on the surface, which can speed up air circulation and solve many problems such as easy to receive ripening gas, moisture, mold, or condensation, so as to keep food fresh. At the same time, the reinforced fibers of the respiratory wrapping film can also prevent the stretch film from breaking and provide better load-bearing capacity.
The breathing stretch film not only has the characteristics of the traditional stretch film but also solves the difficulty of air permeability and water vapor generation. Therefore, it is used to pack fruits, flowers, meat, hot-filled beverages, etc. For several days and will not rot or become moldy due to strong sealing.
According to the purpose, it can also be divided into airport luggage packing stretch film, slimming stretch film, etc.
In fact, these cling film “envelopes” are designed to protect the luggage. It is no secret now. Everyone knows that luggage porters will not be careful to put it lightly because you are using LV luggage in the process of transporting luggage. Many people wrap their luggage for fear of being scratched, overturned on the road, pried open by thieves, and preventing the luggage from bursting.
The slimming film weight loss method mainly uses the lower breathability of the stretch film, and then the heat in various parts of the body increases sharply, causing a lot of perspiration and burning and consuming fat, and finally achieving the effect of weight loss and slimming.
Fifth, according to the number of layers, there are single-layer stretch films and multi-layer stretch films.
Single-layer stretch film is one of the most widely used films, mainly used in packaging in food, medicine, cosmetics and other industries. During production, the polyethylene film is tiled on the bottom of the container, and then the multi-layer stretch film is tiled on the film, and the winding machine rotates at a set speed under the action of compressed air to achieve the winding effect. A single-layer film is mainly composed of two or more layers；
Multi-layer stretch film is a form of packaging that adds another layer of film to the surface of the composite film. It is obtained by winding three or more layers of film, which can provide protection, strapping, transportation and storage functions. The material is three-layer or multi-layer polyethylene film, and the thickness is generally about 0.5mm.
(1) The three-layer composite packaging film has good properties: because of the good adhesion between the three-layer films, it can better protect; because the three-layer composite film has one or more special ingredients, such as antistatic agents, moisture-proof agents, etc., it can effectively prevent moisture and moisture penetration; the three-layer film has strong tensile strength and impact resistance, so it has high compressive strength; the three-layer film has good compressive strength to ensure the safety of packaging; because the material is thicker, it has a good heat resistance and cold resistance.
(2) The multilayer film has good elasticity and toughness. Multi-layer film has strong tensile strength and impact resistance when packaging, so it can realize the automation of item packaging.
(3) The multilayer film can play a good role in shockproof, anti-static and dustproof during transportation. Because the product itself has moisture-proof, dust-proof, and shock-proof functions, it can improve the product image and extend the product’s shelf life.
(4) The multilayer film has strong antistatic properties. Because it contains surfactants and other components, it will cause the surface of the product to be charged under the action of static electricity, which is not conducive to storage and sales. Therefore, the multilayer film can be used as an electrostatic charge conduction carrier. Of course, it can also be used as an electrostatic discharge device.
(5) Multi-layer film properties can be combined in a variety of packaging forms to meet different needs.
