Characteristics and defect treatment of composite film packaging
in daily life, we can see composite film packaging everywhere. Foil plating film with high technical requirements is usually used for color printing. In order to produce composite films with different firmness requirements, the interaction between various materials is required - the interaction between synthetic material films, drilling agents and printing oil displays
a continuously growing market
in recent years, the total amount of flexible packaging has been increasing, which also fully shows the trend of flexible packaging replacing bulky packaging such as glass bottles and metal cans. This is not only because of its cost advantage, but also because it can adapt to the market demand faster and better. Michelin North America has combined the change of kitchen grade sunflower oil into its new luxury travel tire primacy mxm4. The more and more complex multi-layer composite technology (three-layer and four layer composite) makes it adapt to the expanding application fields and increasing various related requirements. According to the characteristics, the composite film market can be divided into three parts: the off-end market of packaged liquid goods: the intermediate market of packaged cheese, fresh meat, etc., and the low-end market of packaged fast food, instant noodles and other goods
barrier characteristics of composite film
through the interaction of different materials in the composite film The advantages of each layer have been accumulated. The following are the functions of the composite film:
1 Water vapor barrier, prevent wet goods from drying. Add wet wipes for cooling: protect dry goods from moisture, such as baked products and powdered products
2. Acid barrier Prevent oxidation, such as for fat and fresh goods
3. Carbon dioxide barrier. Prevent the loss of carbon dioxide in map packaging to achieve stable packaging gas composition of carbonated beverages
4. Fragrance barrier. Protect the fragrance from volatilizing from the package and losing it, such as coffee
5. Odor barrier. Prevent absorption of external odor or loss of fragrance
6. Light blocking. Prevent light oxidation, such as dairy products
7, firmly sealed. For the sealing of composite films, hot pressing sealing is used
aluminized film has the best barrier characteristics. Vaporizing the metal onto PET plastic film can also achieve the characteristics very close to that of aluminum plating. Vaporization of aluminum compounds or silicon oxides onto pet or OPP plastic thrusts also has a good barrier function. But there is no good light blocking ability
formation of composite film
formed by two or more layers! The composite film must be as inseparable as a film. This not only involves the drilling agent between the two films It is also related to ink film. Drilling agents are synthetic products. Most drilling agents are two-component polyurethane (PU) drilling agents The chemical reaction in the drilling process solidifies the drilling agent. The drilling agent on the surface of the substrate is mainly a physical process, and only a small part is a chemical process. At this time, the components of the drilling agent and the components in the plastic film are drilled together and further solidified
if a film has been printed in the drilling process, the drilling agent can effectively reduce the cost and the ink should meet more requirements. The most basic requirement is that the inner layer before compounding should have good adhesion fastness and thorough drying. The more it smells No solvent residue is allowed in the printed inner film. However, solvents or alcohol are often left in the connecting materials of ink. For this reason, the performance of drilling agent must be able to combine with free radicals (-oh). Otherwise, the drilling agent and curing agent will react with each other and lose their felicity. For example, in the compounding process, the film has been printed with PVB ink, and there is isoparaffinate left in the ink, Chemical base of the salt NCO radical) will react with the free radical Oh of alcohol and water. There is no residue, which leads to the insufficient reaction of the drilling agent. Then comes the insufficient curing and drilling force.
in the drilling agent, the solvent-based drilling agent is different from the solvent-free drilling agent such as UV drilling agent. The solvent-based drilling agent needs an oven to volatilize Luo agent. When using UV drilling agent, UV light passes through the film to reach the drilling agent Polymerize the adhesive
ink suitable for composite film
ink suitable for composite film should not only have good adhesion on various films (OPA, OPP, pet-alox, pet SiOx, PE, ALU), fully drill with drilling agent, strong cohesion (cohesion of ink), but also non-toxic safety. In addition, the further requirements for the composite film printing oil are: printing lasting patterns, sterility and pasteurization, simple stamping and perfect color treatment, and rapid solvent volatilization
for composite film printing The progress of nitrate plastic granulator technology is closely related to the development of the whole national economy. The cellulose (NC), polybutylene (PVC), polyethylene butyraldehyde (PVB), nitrocellulose turbulence polyacetic acid (nc/pu) Pan system should be considered first. It can be seen that the more plastic the system is adjusted The more firmly the oil adheres to the substrate So the composite fastness is better. PVB ink system is suitable for almost all drilling applications. This system is currently the most widely used
nc/pu oil star system appeared late But it has better performance in stamping, color processing and cleaning. It is a "universal" suitable for flexo printing and gravure printing "The oil in system is very environmentally friendly, with few failures under high-speed printing, rapid solvent evaporation, sterilization and pasteurization lasting. It does not contain plasticizer components. At present, its market position is still relatively low, but it has shown a growth trend. The PU ink system widely used in Asia has characteristics and trends similar to nc/pu ink system. It first needs to be printed with a layer of white ink when printing.
The amount is gradually decreasing. Because the ink it uses contains' grade 'components, it cannot be used in packaging. In addition, the "vinegar" contained in it "Components will weaken the performance of photopolymer version, so this ink system has not been considered in flexo printing. Therefore, at present, it is only used in gravure printing.
due to the turbulence of the penetration and transfer of components in oil and drilling mixture, it is easy to cause environmental pollution. Therefore, relevant laws and regulations have restricted this, especially involving the composite membrane packaging of food and drugs.
in daily life, when consumers You should be especially cautious when choosing composite film wrapped safety devices to pack food, because whether the food packaging is environmentally friendly is related to your health If juice, soy sauce, olives, vinegar alcoholic beverages, skin care products, detergents, disinfectants, bleaches, etc. use inappropriate inks and drilling agents, it is possible that these inks or drilling agents will be incorporated into beverages or foods, which will affect the health of consumers
monomer plasticizers also from oil or drilling agents may also penetrate (migrate) into the product. In addition The persistence of pasteurization, sterilization or heat sealing and the drilling of composite membrane will be reduced if inappropriate oil system and drilling agent are used
when producing all kinds of composite films that not only comply with legal regulations, but also meet customer requirements It is very meaningful to integrate the advantages of different materials into composite films. However, the production process of such composite membrane is also very complex. It is reported that the manufacturer has a comprehensive understanding of relevant tomb materials, oil lining systems and drilling agents And we should also have a deep understanding of the interaction effects between these materials to avoid problems in the post-processing of the composite membrane