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    Home > Active Ingredient News > Drugs Articles > It is said that the thermal seal performance of commonly used thin film materials is compared with that of heat sealing process

    It is said that the thermal seal performance of commonly used thin film materials is compared with that of heat sealing process

    • Last Update: 2020-11-12
    • Source: Internet
    • Author: User
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    Single-layer film Single-layer film has transparent, non-toxic, non-permeable, with good heat sealing bag, heat and cold resistance, mechanical strength, grease resistance, chemical resistance, anti-adhesion.
    can be made by extrusion blow film method, extrusion flow delay method, extrusion method, solvent flow extension method and so on.
    the thermal seal performance of a single-layer film is not only related to the relative molecular mass distribution and molecular disambiguation of the resin, but also to the process conditions of film making, such as temperature, cooling speed, blow-out ratio, etc.
    , how does a single-layer film differ from a composite film? In the soft packaging industry, these problems need to be mastered.
    technical engineers of interstate GBPI recommend several methods for identifying composite films and their structures.
    , judging the type of composite film by appearance Plastic composite packaging film is made from a variety of single-layer film composite, its identification method is different from single-layer film.
    , combined with the performance characteristics of a single-layer film and the purpose requirements of the compound, can be roughly distinguished.
    such as according to transparency judgment, aluminum foil, aluminum coating film, etc. are generally opaque composite film;
    can be roughly judged from the appearance and mechanical properties of the film.
    film II, four tips for quick identification of composite film 1, composite film generally has natural curling phenomenon, such as putting it in hot water is more obvious.
    2, composite film, such as the middle layer and the outer layer of the material is different, then the two sides of the film feel different, careful touch can be distinguished.
    3, cut a small mouth on the film, and then slowly diagonally tear apart, the composite film formed by the different tearing substrates is very easy to layer.
    4, if the printed film, if the printing layer does not rub off, then the printing layer sandwiched in two layers of film, for the composite film.
    these are relatively simple methods of identification of composite membranes.
    more reliable is the physical assay, that is, the thermal analysis method is used to obtain the thermal spectrum, and according to the map will appear the corresponding parts of the melting temperature peak.
    In addition, the microscope method can also identify composite films, because the refractive index of various plastics is different, the stretched double refractive value is different, in the difference or polarity microscope observation, the composite layers will appear different colors, so as to distinguish between single film and composite film.
    , the method of identifying the various components of the composite film is determined to be a composite film, the various components of it should be separated and identified.
    solution or solvent method using different resin dissolving or swelling properties are different, or solvents seep into the interface after changing the interface pressure to separate the layers of the composite film.
    the substrate of the composite film is divided, to find out which kinds of substrate composite, can be peeled off the composite film substrate analysis to determine, but at this time should pay attention to the interference of the adhesive.
    Peeling method The composite film made of extrusion compound or dry compound, after pulling or kneading, is stripped due to inconsistent deformation, a certain heating treatment is carried out, so that the adhesive layer softens and the bonded film is stripped together, and it can also be separated according to the crystalline high-polymer melting point.
    coating glue (dry/wet) composite film: single-layer film has certain advantages, but also inherent disadvantages, often difficult to meet a variety of packaging performance requirements, multi-layer different substrate composite, that is, can complement each other, play a comprehensive advantage.
    foil: 99.5% purity of electrolytic aluminum melting with a press press pressed into foil, soft plastic packaging substrate is very ideal.
    it has good gas barrier, water vapor barrier, light shielding, thermal conductivity, shielding.
    vacuum steamed aluminum film: at a high vacuum, the low boiling point of the metal, such as aluminum, melted and accumulated on the cooling drum on the plastic film, forming a good metallic aluminum coating.
    aluminum plated thickness to meet certain requirements, can greatly improve the oxygen resistance of the substrate, moisture resistance.
    substrate should be treated with corona and coated with sol.
    coating: also known as ceramic coating, no matter how high temperature and humidity, performance will not change, suitable for the production of high-temperature cooking bags.
    two types of coatings: SiOx, a silicon oxide, the smaller the barrier, the better, and Al2O3.
    coating methods have physical and chemical plating methods.
    Extrusion coating composite film: In a extruder, thermoplastics flow through the T-shaped mouth mold on the paper, foil, plastic substrate ready for approval, or extruded resin as the intermediate adhesive, while hot to press together another film substrate, forming a "sandwich"-style composite film.
    in order to improve compound fastness, corona treatment is required and anchor coating is applied.
    extrusion compound film can be backprinted, the thickness of each layer can be precisely controlled, solvent residue is small, cheap.
    total extrusion composite film: using two or three extruders, a composite die is shared, layered between several compatible thermoplastics, to produce a multi-layer film or sheet.
    co-extrusive composite film can only be printed on the front and not backprinted.
    , the thickness control of each layer is more difficult than that of dry compound film and extrusive lysofilm.
    do not use adhesives and anchor coating agents, pollution-free hygiene is good.
    cost of co-extrusing compound film is low.
    high barrier film: is a multi-layer structure of the film.
    film can effectively prevent the infiltration of gases such as oxygen, which can cause microbial reproduction, prevent the oxidation of encased items, prevent the smell of goods, solvents, etc.
    Often referred to as high barrier high-strength materials, such as EVAL, PVDC, PET, PAN, selar PA, etc. into packaging film, can significantly extend the shelf life of food, or can replace the barrier performance of traditional rigid packaging materials.
    Fresh and sterilized film Preservation and sterilization film: (1) ethylene adsorption film, in the film to add zeolite, square stone, silica and other substances, can absorb fruits and vegetables exhaled ethylene gas, inhibit its maturation too fast.
    (2) anti-dew fog film, multi-water green fruit packaging film inner surface more dewy fog, easy to make food mold.
    Add anti-fog anti-drop agents such as stingric acid monoglycerides, polyol fatty acid derivatives, sorbitol and hard lipids in thin film materials, and add waterproof aerosols such as fluorine compounds to effectively prevent food mold.
    (3) antibacterial film, in the plastic material with ion exchange function of synthetic zeolite (SiO2 plus Al2O3), and then added inorder fillers containing silver ions, silver sodium ion exchange into silver zeolite, its surface has antibacterial properties.
    the use of co-extrusion composite process can make the film with 6 m of silver zeolite inner layer, when the concentration of silver ions up to 10 to 50 ppm can completely kill the bacteria on the surface of the green fruit.
    (4) far infrared preservation film, mixed into the plastic film ceramic filling agent, so that the film has the function of producing far infrared, in addition to sterilization, but also to infraspirate the cells in the green fruit, so there is a preservation function.
    aseptic packaging diaphragm: mainly used in food and pharmaceutical aseptic packaging production, requires: sterilization capacity, high barrier and strength, good heat and cold resistance (-20 degrees C not brittle), good needle-resistant bending resistance, printing patterns in high temperature sterilization or other sterilization methods will not be damaged.
    high temperature cooking bag: high temperature cooking bag can be divided into transparent type (shelf life of more than one year) and non-transparent type (shelf life of more than two years), high barrier type and ordinary type.
    are divided into low-temperature cooking bags (100 degrees C, 30min), medium-temperature cooking bags (121 degrees C, 30min), and high-temperature cooking bags (135 degrees C, 30min).
    the inner material of the steaming bag is used with various flow and bloating PE (LDPE, HDPE, MPE) films, high temperature flow delay CPP or blowing IPP, etc.
    EVAL, aluminum foil, PVDC film suitable for the middle layer.
    two-way stretch PET, nylon 6 and other suitable surface materials.
    polyester-type two-component polyurethane adhesive is suitable for dry compound film adhesive.
    The main advantages of high temperature cooking bag: (1) high temperature cooking can kill all bacteria, 121 degrees C/30min can kill all Botox;
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