The hottest modification technology improves the p

2022-09-27
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Modification technology improves the performance of polyester products (Part 2)

surface coating modification

surface coating method is another common method to improve the barrier property and other properties of PET film. DSM serves food and health products, personal care, feed, medical equipment, automobile, coating and paint, electronics and electrical, life protection. Most plastic beer bottles in foreign markets are pet coated products. For example, coating polyurethane, EVOH, PVDC, etc. can improve the barrier of polyester bottles to oxygen and carbon dioxide; For BOPET film, the process of coating polyvinylidene chloride lotion can also be used to improve its barrier performance. If the transparent coating containing ultraviolet (UV) absorbent (such as epoxy acrylic polymer, polyurethane acrylate, polyester acrylate) is coated, it can form the UV protective layer of polyester film, which can enhance the UV resistance of PET film. For another example, coating a polymer solution on the surface of BOPET film can significantly improve the surface properties of PET film. The test shows that the surface wet tension of the PET film coated with a certain polymer solution can be as high as 60mn/m, which greatly improves the printing and aluminizing properties of the PET film. Moreover, the two conventional materials of coated PET film are corroded and rusted due to the presence of salt water, and the surface wet tension will not decay under high temperature and high humidity climatic conditions. Another advantage is that after aluminizing, there will be no delamination of aluminized layer due to contact with aqueous solution. These two points cannot be compared with the commonly used corona treatment methods

in addition, if a layer of "matting" material is coated on the surface of PET film, PET film with matte effect can be prepared

multi-layer coextrusion modification

as mentioned above, in order to make the ordinary PET film have heat sealing property, a layer of copolyester PETG can be extruded on one of the surface layers of the three-layer coextrusion production line, which will not be repeated here

to improve the barrier, heat resistance and radiation resistance of BOPET film, a layer of pen can be extruded on one of the surface layers of the three-layer coextrusion production line. Because pen and pet belong to polyester, they have good compatibility. The BOPET composite film (pet+ masterbatch/pet+ recycle/pen+ masterbatch) prepared by three-layer coextrusion has a great improvement in the properties of barrier and heat resistance compared with ordinary PET film in the face of the continuous development of the plastic industry, hydrolysis resistance and radiation resistance, but the price is much cheaper than pure bopen film. It should be said that this is the development direction of flexible plastic packaging

nano modification technology can improve the barrier property of pet and make it suitable for beer packaging. (Photo courtesy: kefang incubator)

modification of nano materials

nano materials refer to materials with a particle size of nano magnitude nm (1nm=m), which is a new generation of materials composed of nanoparticles with a size between atoms, molecules and macro systems. Because the size of nanoparticles is very small, they have unique quantum size effect, surface effect, interface effect, volume effect, macroscopic display tunnel effect, small size effect and so on. Therefore, nano materials have many characteristics. This leads to many special properties of the system composed of nanoparticles, which are different from the usual bulk macro material system

nano plastics are composites of nano materials such as silicate, calcium carbonate, SiO2, TiO2, montmorillonite, etc., which are uniformly dispersed in the plastic matrix resin with nano size (generally nm). According to different synthetic resins, they can be classified into: nano nylon, nano polyolefin, nano polyester, etc. The amount of inorganic nanoparticles in nano plastics is less, generally 2%-5%, which is only about 1/10 of the amount added when inorganic fillers are modified

compared with the original parent resin, the improved and improved properties of nano plastics have the following characteristics:

improve mechanical properties. Its bending modulus (rigidity) can be increased by 1 Times

improve heat resistance. The thermal deformation temperature can be increased by more than ten degrees, and the thermal expansion coefficient can be reduced to half of the original

increase plastic barrier. Reduce the transmittance of the material to carbon dioxide and oxygen to the original 1//5

improve the transparency and pigmentation of materials

improve the flame retardant grade of the material

improve the dimensional stability of materials, etc

montmorillonite (MMT), the most commonly used nano inorganic material in nano plastics, is a kind of natural clay mineral rich in China. It is a layered silicate, and its structure: the lamella is nano scale, including three sublayers. An aluminum oxide octahedral sublayer is sandwiched between two silicon oxygen tetrahedral sublayers. The sublayers are covalently connected by sharing oxygen atoms, and the bonding is extremely firm. Montmorillonite can further react with monomers or polymer melts. In the process of monomer polymerization or polymer melt mixing, it is stripped into nanoscale structural layers, which are evenly dispersed into the polymer matrix to form nano plastics. The amount of montmorillonite in nano plastics is less, usually only 2% - 5%, but its rigidity, strength, heat resistance and other properties are equivalent to those of conventional glass fiber or mineral filled reinforced composites. Therefore, the proportion of nano plastics is low, and its specific strength and specific modulus are high without losing its impact strength, which can effectively reduce the quality of products. At the same time, because the size of nanoparticles is smaller than the wavelength of visible light, nano plastics have high gloss and good penetration. Customers also have their own unique insight into various problems of the experimental machine. It is worth mentioning that it also endows the material with flame retardancy. At present, the additives of flame retardant plastics mostly use halogen-containing compounds. The smoke generated by this halogen-containing flame retardant during combustion contains corrosive hydrogen halide and carcinogens, which does not meet the requirements of environmental protection. Therefore, the demand for halogen-free flame retardant materials is growing. If general aluminum hydroxide and magnesium hydroxide inorganic flame retardants are used, the mechanical properties of materials will be greatly affected due to the large amount of additives, so the use of flame-retardant self extinguishing nano plastics is a more appropriate option

in a word, nanocomposite modification has become one of the main ways to prepare advanced packaging materials, and its application prospect is very broad

source: fengshu, Jiangyin jinzhongda new materials Co., Ltd

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