The odor sources in the film mainly include these parts: various additives of the resin itself and its own low-molecular-weight substances; odors generated during film processing; odors generated during flexible packaging processing; odors generated during storage. 1. The influence of the resin itself 1. The film is generally processed with high molecular weight resin. The resin is composed of different molecules, and the molecular weight distribution of different resins is different, and the content of low molecules is also different. Low-molecular-weight substances are easily oxidized and volatilized during extrusion processing, resulting in odor. 2. The resin synthesis process is divided into the solution method and the meteorological method. The two different synthesis methods themselves also have differences in odor: the solution method undergoes the process of removing the solution after synthesis, and many low-molecular substances are removed, so the taste In theory, it is better than meteorological law. 3. Many additives must be added to the resin to improve performance. These additives are the biggest source of taste: the slip agent is generally an amide compound, which has a sweet taste. The smell of antistatic agent is very pungent, so it should not be used in low-odor packaging. The antiblocking agent is generally based on inorganic substances, usually calcium carbonate and silica. But in terms of opening effect, silica is far better than calcium carbonate. But in terms of taste, calcium carbonate is better than silica. Antioxidants are usually phenolic things, and they also have a certain taste. Generally, linear molecules have the problem of residual catalyst, so antioxidants must be added. Color masterbatch: Commonly used white masterbatch usually adds some wax and stearate as dispersant and lubricant. These low-molecular-weight substances will precipitate during processing and have a great taste, so they should be placed in the middle layer as much as possible in multi-layer co-extrusion. Second, the influence of film processing technology Generally speaking, the higher the processing temperature, the higher the peculiar smell. Because the low-molecular-weight substances in the resin will be easier to volatilize in the high-temperature processing environment. A small amount of carbonic acid, aldehydes and other substances produced by high-temperature oxidation will cause a strong odor. Therefore, in theory, the cast processing will have a higher taste than the blown film. The equipment with internal cooling is definitely better than the one without internal cooling. The taste of down-blowing water cooling will be the lowest. Third, the influence of the flexible packaging processing process. For the time being, the taste of the film is not considered. In the flexible packaging processing, the control of ink, adhesive, solvent and printing composite technology also has a great influence on the taste of the film. 1. Printing inks are divided into benzene type and non-benzene type. Non-benzene type is divided into polyurethane type and alcohol-soluble type inks. Different substrates use different inks. Each series of inks has different tastes due to different resins and pigments. . Therefore, the choice of ink with low taste and good solvent release effect is particularly critical in the processing of flexible packaging. 2. In compound processing, we usually use two-component solvent-based polyurethane adhesives, two-component solvent-based aliphatic adhesives, and two-component solvent-free polyurethane adhesives. In order to ensure the different performance requirements of packaging bags, There are a lot of knowledge in the choice of adhesives. Various grades of adhesives are very functional and have large performance differences. Therefore, we must consider both the influence of the adhesive itself on the taste of the film and the strength between the composite layers. Whether it meets customer requirements. 3. In the evaluation of the odor of the film, we found that if the solvent used to dilute the ink and the adhesive is not sufficiently volatilized during the printing and lamination process, it will cause too much solvent to remain between the composite film layers. These solvents will pass through Slow migration and gradual contact with the contents will change the taste of the food. It seems that it is very important to set reasonable process parameters and carry out effective online control. In addition, with the rapid development of the industry in recent years, solvent-free coating technology has been widely adopted, it can effectively avoid the risk of solvent residues, and it should be said that it is a good choice for composite processing. Fourth, storage conditions The resin and finished products should be placed far away from odor sources. If placed in an odorous environment for a long time, irritating molecules will be adsorbed on the surface and cause some special flavors. The same is true in transit. The storage temperature should be lower than 35 degrees, otherwise the low-molecular-weight substances will migrate out quickly, causing the taste to increase. The ambient temperature in the processing workshop should not be too high, otherwise low-molecular substances will precipitate out during the production process. In short, if you want to achieve low odor, you must first consider the selected resin in the design of the film. The various additives in the formula should be as few as possible, and the processing temperature should be as low as possible. It is best to use internal cooling. The equipment or down-blowing water-cooled process production. Only in this way can the soft package factory obtain customer-satisfied, low-tasting films. Is a company specializing in the production of PET film with multiple functions, such as: transparent PET film, milky white PET film, release PET film, supply of PET motor film, etc. With a wide range of products, affordable prices, and environmental protection, we provide customers with excellent quality and service based on the service tenet of excellence in production, honesty and trustworthiness in distribution, warm and thoughtful service, and the spirit of assisting partners to achieve their own careers. Interested parties welcome to inquire!