Comparison of characteristics of plastic film for

Comparison of the characteristics of "plastic film" used in packaging

plastic film, as a printing material, has a relatively short history. It is used as a packaging after printing. With the release agent added into the system material, it has the advantages of lightness and transparency, moisture and oxygen resistance, good air tightness, toughness and folding resistance, smooth surface, can protect goods, and can reproduce the shape and color of goods

with the development of China's industry, there are more and more varieties of plastic films. The commonly used plastic films include polyethylene (PE), polyvinyl chloride (PVC), polystyrene, polyester film (PET), polypropylene (PP), nylon, etc. The properties of various plastic films are different, the printing difficulty is also different, and the use as packaging materials is also different

polyethylene film is a colorless, tasteless, odorless, translucent and non-toxic insulating material, which is widely used as packaging bags; Food bags can also be made into various containers. It is an inert material, so it is difficult to print. It must be processed before it can produce a better effect

PVC thin film has good light resistance and aging resistance, and has good tear resistance. It is breathable. It is a clean, colorless and transparent film. Generally, plasticizer is added. It is soluble in acetone, cyclohexanone and other solvents. Therefore, it can be printed with ink made of PVC resin. Suitable for packing bags, book covers, etc

polystyrene film is a soft and tough film, which is clean, colorless and transparent. When there is no plasticizer, the film is always soft, freezing resistant, and aging free. When printing, the synthetic binder ink of oxidative polymerization is used, which can make the imprinting fastness better

polyester film is colorless, transparent, moisture-resistant, airtight, soft, strong, acid and alkali resistant. This development summarizes the steps and methods to directly design the properties of materials required according to big data. Esters and solvents, materials that are not afraid of high and low temperatures, have better surface fastness to inks after spark treatment. For packaging and composite materials

polypropylene film has good gloss and transparency. It is heat-resistant, acid-base resistant, solvent resistant, friction resistant, tear resistant and breathable. It cannot be heat sealed below 160 ℃

nylon film is stronger than polyethylene film. It is tasteless, non-toxic, bacteria resistant, oil resistant, ester resistant, boiling water resistant and most solvents. It is generally used for heavy and wear-resistant packaging, as well as cooking packaging (reheating of food). It can be printed without surface treatment

polyethylene molecules basically do not carry polar groups, which is a kind of non-polar printing. In polypropylene molecules, each structural unit contains a methyl group. These weak polar groups basically improve the operation efficiency, and they also belong to non-polar polymers. Therefore, their affinity for ink is relatively poor, so they need to be treated before printing to get a satisfactory print

most of the treatment methods are through oxidation to increase the polarity and change the surface structure. Specific treatment methods include discharge (commonly known as corona, electric spark) method, flame method, ultraviolet radiation method, acid (sulfuric acid, chromic acid) treatment method, etc. The discharge method is relatively simple and popular

the effect of corona treatment is related to the output power of the treatment equipment, the distance between the two electrodes, the discharge area of the electrode, the treatment speed, the treatment method (heat treatment or cold treatment) and the number of times. The treated film must be printed immediately, otherwise it may still fail

in spark treatment, due to the free radical reaction produced by corona discharge, the polymer may be crosslinked, the surface becomes rough and increases its wettability to polar solvents. Generally speaking, the printing of plastic film can be improved in three aspects after rare pretreatment (Performance: antistatic agent can be used to add a wide range of loading agents). Trihydroxydodecylamide ethyl quaternary amine perchlorate is used in China, In order to improve the reduction effect of electrostatic charge attenuation and enhance the adhesion effect of ink, the wettability of solvent based ink has been improved in gravure printing and chiral printing

the printing method of plastic film can adopt flexo, gravure and silk printing. The printing ink is required to have the characteristics of high viscosity, strong adhesion, which can make the ink molecules firmly adhere to the dry plastic surface, and it is very easy to form a film with oxygen in the air and dry. Generally, the ink used for Gravure plastic film is composed of synthetic tree esters such as panamine, organic solvents and pigments dominated by alcohols, which are fully ground and dispersed to form a colloidal fluid with good fluidity. It is a volatile dry ink, which has the characteristics of good printing performance, strong adhesion fastness, bright color, rapid drying and so on. It is suitable for printing with gravure wheel rotary machine

reprinted from: medium waste