1 high barrier silica
SiOx was coated on the inner surface of injection stretch blow-molded PET bottles by Glaskin[7-8] method. SiOx coating is transparent, waterproof and distillable, and its barrier performance is excellent, even reaching the level of glass. The results show that the storage period of beer can reach 4 ~ 65438 0.2 months by using this technology, which meets the requirements of beer storage period (65438 0.20 d in the United States and 65438 0.80 d in Europe). The disadvantages of S i Ox are small bending, poor fracture resistance and high cost. Many companies [4,9-12] have applied SiOx as the barrier layer of PET bottles.
⒈2 Amorphous Carbon Deposition Technology
Actis (amorphous carbon treatment o n in international surface) was developed by Side EL Company of France, and a layer of amorphous carbon was sprayed on the inner wall of PET bottle by plasma enhanced chemical vapor deposition (PECVD). Act is coating is amber and transparent, and its thickness is/kloc-0 /×10-7 m. This technology can greatly improve the barrier performance, and the barrier C O 2 is increased by 7 times and O 2 by 3 0 times or even 35 times. In addition, depositing a hard carbon layer (DLC) on the inner wall of P E T bottle by chemical vapor deposition (CVD) technology can improve the barrier performance of PET bottle to O2 by 10 times. At the same time, the coating is not affected by acid or alkali, and the color is light brown.
⒈3 epoxy amine
Bairrocade is a product of industrial company, which is an epoxy amine. Liquid epoxy amine is sprayed on the outer wall of the P E T bottle, and then cured in an infrared oven. Compared with other barrier coatings, epoxy amine has better stability to temperature and humidity, and at the same time, the coating can also withstand pasteurization. The test of PPG Company showed that the barrier of Ba i ro c a d e to O2 increased by 65438 0.2 times, and the shelf life of beer exceeded 3 months.
4 others
Including Arthur i c a technology of Te t r a Pa k company, Blox coating of DowCh emi ca l company and organic-inorganic mixed coating. * * * Mixing or * * * Polymerization is a compromise between performance and cost. The resin with excellent barrier performance is mixed or polymerized with P. E. T to improve the barrier performance. Technically, they are simpler and cheaper than the multi-layer composite extrusion process. At present, the resins used in this method are MXD6(PA), LCP and PEN [5-6, 15- 18]. The barrier performance of MXD 6 is 9 ~ 20 times that of/kloc-0 of PET. Because it has similar processing conditions with PET, it is easier to mix with P E T ***. Its disadvantage is that the transparency of the bottle will decrease with the increase of MXD6 content [2, 19]. Nanocor Company [4] modified M X D 6 with its nano clay, and the barrier performance of M 9 to CO2 and O2 was improved by 5 0% and 75% respectively compared with MXD6. The barrier property of LCP to O2 is 2 00 times that of PE T, and it is not easily affected by humidity. Due to the different molding conditions of LCP and PET, there are some difficulties in injection stretch blow molding, and the molded bottle is opaque.
The structure of P EN is similar to that of P ET, but because naphthalene is more rigid than benzene ring, PEN has more outstanding properties than P E T, such as high tensile strength and modulus, low shrinkage and so on. , and can prevent ultraviolet rays and remain transparent. The barrier performance of PEN to O2 is four times that of PET, and the barrier performance to CO2 is five times that of PET, and its glass transition temperature is 120℃. However, due to the price (about 6 times that of PET), its application is limited. At present, about 7 0% of barrier PET bottles belong to multilayer composite bottles, usually 3, 5 or 7 layers. Multilayer composite technology can minimize its own shortcomings while making use of the excellent barrier properties of materials, such as EVOH, which is very sensitive to water. When the glass transition temperature of dried EVOH is 70℃ and the moisture content is 8%, the glass transition temperature is lower than room temperature because water plasticizes EVOH.
The materials used in PET multilayer composite bottles generally include MXD6, EVOH, thermoplastic epoxy resin and oxygen scavenger. For example, a three-layer bottle with MXD 6 as the barrier layer can be used for packaging hot-filled food and beer. With the three-layer structure of PET/EVOH/PET, the storage period of beer can be extended to 12 weeks, and the barrier property of PET/LCP bottle containing 4.5%LCP can be reduced by 70%. There are many kinds of pet beer bottles developed in the world with different functions. The United States has developed a pet beer container coated with hard carbon film. The raw material of pet bottle body is hydrogen carbide, and the film contains 60%-90% amorphous carbon and 65,438+00%-40% hydrogen. The thickness of the film is 200-400 angstroms, and the barrier capacity is improved by more than 65,438+00 times. The material is flexible and the film will not be damaged during stretching. Hard carbon film can absorb slight odor, block fragrance, and has excellent chemical stability, acid and alkali resistance, high temperature resistance (300℃), transparency and high altitude, which is safe to use and meets fda safety standards.
In the United States, diamond-like carbon (dlc) was coated on the inner surface of pet plastic bottles by vacuum plasma enhanced chemical vapor deposition technology, which played a barrier role between beer and bottles and improved the gas barrier property of pet by 5- 10 times. The pet bottle coated with dlc film has little smell and little adsorption on beer aroma, so it can be recycled and refilled with beer.
The 3-layer PET/N/PET beer bottle produced by schmalbachlubeca Company of the United States adopts the aluminum crown cap with pk pull ring made by growncork Company of Japan, which weighs only 25g and can keep the beer shelf life for 6 months. The pet/EVOH/pet three-layer beer bottle and the PET three-layer beer bottle with deoxygenated material as shielding layer are also developed, which meet the requirements of environmental protection and can be recycled.
Miller Company of the United States developed a pet beer bottle with a five-layer structure of polyamide shielding layer (pet/ shielding layer /pet/ shielding layer /pet), which is made of two layers of plastic resin, namely pet and shielding resin material. The core layer pet is made of shielding resin material, and the core layer pet can be recycled after consumption. The bottle is made of cpt patented technology. After pasteurization, the bottle body will not be deformed, broken or softened, and its physical properties and strength are stable. The shelf life of beer is more than 4 months, which is basically the same as that of beer packaged in glass bottles and metal cans. At present, the brands of pet packaged beer that can be seen in China market mainly include 1 and Suntory M ⅸ beer, which belong to the fruit-flavored beer series with bright packaging and three flavors of peach. 2. Belgian Maxwell beer, following the Belgian Martens flavor, has a mellow taste; 3. Silver Lion Beer, adhering to the American brewing concept, is packaged in pure draft beer in PET bottles, with fresh and pure taste; 4. Blue-shell beer, after being integrated with Blue Ribbon China, introduced a pet bottle with heavy taste and strong lethality;