Production technology and application conditions of heat shrinkable packaging film

PVC heat shrinkable film can package different kinds of products, and the heavy metals do not exceed the standard. It is characterized by relatively low shrinkage temperature and slow heat shrinkage speed, and generally it can achieve excellent results at 80-120 degrees. The product has high transparency, clarity and strong gloss. Instant heating and easy shrinkage are suitable for all types of shrinking machines, which are widely used and suitable for low-cost and low-cost product packaging.

Such as: wood products, craft gifts, candles, brochures, printed matter, electronic appliances and other industries. At the same time, it can be made into various flat pocket, arc bag, special-shaped bag and triangle bag. Tight packaging, beautiful and generous, flame retardant. Printing does not fade. PVC heat shrinkable film can be used for insulating packaging of electrical appliances and electronic components (such as the outer packaging of dry batteries); Packaging of general goods and packaging of food contact. Using it as packaging material can not only simplify the packaging process and reduce the packaging volume, but also show the color and shape of the packaged goods clearly because the shrunk transparent film tightly wraps them, so PVC heat shrinkable film is widely used in commodity packaging.

PVC shrink film has the characteristics of good transparency, good toughness, no fear of impact and low water vapor permeability. When the film is subjected to the corresponding temperature, it automatically shrinks and tightly wraps the goods, thus achieving the functions of protecting the goods, rust prevention, pollution prevention, breakage prevention and theft prevention. The goods have good storage and transportation stability, and the packaging technology and equipment are simple, which is convenient for automatic heat-shrinkable packaging.

Characteristics of thermosetting plastics in the production of heat shrinkable packaging film;

1. Amino heat shrinkable packaging films include urea formaldehyde, melamine formaldehyde and urea melamine formaldehyde. They have the advantages of hard texture, scratch resistance, colorless and translucent, and colored materials can be made into colorful products. Because it is not afraid of oil, weak alkali and solvent (but not acid), it has good acid resistance.

2. Thermosetting heat shrinkable packaging film refers to plastics that can be cured or have insolubility under heating or other conditions, such as phenolic plastics and epoxy plastics. Thermosetting plastics can be divided into formaldehyde crosslinking type and other crosslinking types. Resin molecules are crosslinked into a network structure through linear structure. Further heat will decompose. Typical thermosetting plastics include phenolic resin, epoxy resin, amino group, unsaturated polyester, furan and polysilane, as well as new plastics such as polypropylene phthalate. They have the advantages of high heat resistance and not easy to deform when heated. The disadvantage is that the mechanical strength is generally not high, but it can be improved by adding fillers, laminates or molding materials.

3. The material can be made of all kinds of suitable fiber or rubber fillers and some toughening agents, if necessary in an earthquake. In addition, aniline modified phenolic resin, epoxy resin, polyvinyl chloride, polyamide and polyvinyl acetal can also be used to meet the requirements of different uses. Phenolic laminate can also be made of phenolic resin, which has the characteristics of good electrical performance and easy processing, and is widely used in low-voltage electrical equipment.

4. Thermosetting plastics made of phenolic resin as the main raw material, such as phenolic molded heat-shrinkable packaging film, have the characteristics of strong durability, stable size and no fear of other chemicals except strong alkali. Various fillers and additives can be added according to different purposes and requirements. If the insulation performance requirements are good, mica or glass fiber can be used as filler; For varieties not afraid of heat, asbestos or other fillers not afraid of heat can be used.

Heat shrinkable film, LLDPE stretch-wound film is made by adding tackifier, heating, extruding, casting and cooling by chilling roller. It has the advantages of strong toughness, tear resistance, high viscosity, thin thickness, no fear of cold, heat, pressure, dust, water, single-sided adhesion and double-sided adhesion. It can save materials, labor and time when used, and is widely used in papermaking.

Heat shrinkable film Film Blower is a mechanical equipment that melts PE plastic particles by heating and then blows them into films. At first, dry polyethylene particles were added into the hopper, and the particles entered the screw from the hopper by their own weight. When the particles came into contact with the inclined edge of the thread, the rotating inclined edge faced the plastic and produced a thrust perpendicular to the inclined edge surface, pushing the plastic particles forward. During the pushing process, the plastic particles gradually melted due to the friction between the plastic and the screw, the plastic and the barrel, and the collision and friction between the particles, and at the same time, due to the external heating of the barrel. The molten plastic passes through the filter screen of the head to remove impurities and comes out of the die mouth. After being blown up and cooled by the air ring, it is pressed by the herringbone plate, and the finished film is wound into a tube by the traction roller.