Compared with traditional packaging materials such as paper, wood, metal and glass, plastic is completely new. In past decades, however, plastic has exhibited the trend of surpassing other packaging materials in the packaging sector. In addition, it challenges the dominating position of paper packaging. The new technologies and new materials related to plastic packaging have been constantly developed, further pushing the growth of plastic in packing.
Market trend for plastic packaging
Though glass and metal still hold share in some sectors, the packaging sector is now mainly dominated by paper and plastics, forming a keen competition between plastics and paper. Only those who can take over a larger share from metal and glass packaging or other competitors are expected to play an important role in future market.
In the US packaging market, as estimated in research report released by Freedonia Group, plastic consumption will exceed that of papers and maintain 1.6% annual growth rate by 2006. As pointed out in the report, the expansion of the flexible packaging market has triggered the growth in plastic consumption and the competitiveness for plastic packaging is remarkably higher than paper due to its unique properties in processability and recycling. In the US packaging market, plastic consumption will exceed paper consumption in 17 small sectors by 2006, with total consumption hitting 4.9 million T.
According to the estimations of the report, market applications such as various packaging of candy, beverage, fast food and bulk food will witness further expansion by 2008. With the expansion of applications for metal coating and high-barrier laminated film, their market demand will increase too. By 2008, the market share of plastics in the packaging market will go up to around 50%. Compared with the past decade, plastics will maintain a slower growth rate in market share. Still, improvement in plastic performance will continue acting as stimulation to help extend warranty period for commodities, reduce material consumption and improve packaging convenience.
Development in new packaging technology
Whether plastic packaging will eventually outdo paper packaging largely depends on the breakthrough of packaging technologies. To sum up, plastic packaging materials are developing towards the direction of high-barrier, preservative, aseptic, packaging/processing integration and degradable packaging materials.
High barrier technology
Diversified barrier technologies have been available for long and they can meet the requirements of extended shelf time. Today, laminating process is the barrier technology that processors most favor. Structurally, this technology adopts polyester as inner/outer layers and EVOH, PEN or nylon as barrier layer. PEN features high cost and its application has been gradually reduced. For instance, the three-layer composite plastic beer bottles developed by Zhuhai Zhongfu is using EVOH or nylon as barrier layer. Relatively, laminating process is complicated but can reduce cost while ensuring good barrier property.
Active oxygen barrier has been the focus for barrier technologies in recent years. Invista in USA has invented single-layer PET barrier bottles with active oxygen barrier properties and conducted trial application in beer breweries. Besides, Huhtamaki in UK has successfully developed a new-type of plastic packaging material with double functions of passive and active barriers.
Nanotechnology is also one of the key methods to achieve product functions and barrier properties. U.S. Polyester Manufacturer and Eastman Chemical have jointly developed nylon-based nanometer composite material Imperm for PET co-extruded multilayer blow-molding, which can be used as barrier core-layer material for PET/Nylon/PET three-layer bottles. Chinese Academy of Sciences (CAS) has successfully invented nanometer PET beer bottles for beer packaging to meet the requirements of extended shelf life.
Preservative packaging technology
China is the largest fruit/vegetable producer and seller in the world. However, about 30% of fruits in China are damaged during the process of storage and transportation. To retard metabolism process, reduce the loss of nutritious substances and keep fruits flavor and quality has become an essential task for preservative packaging. In Japan, there is a type of permeable preservative plastic film for fruits storage and preservation. It consists of two layers of translucent films with excellent permeability and a layer of amylose syrup with high osmotic pressure sandwiched between the two layers. Fruits packaged with this film can remain fresh and maintain moisture balance.
A new method invented by U.S. scientist, namely, to use plasma vaporization coating technology to form a layer of flexible polyester film on the outer layer of plastic bottles, may keep food in bottles fresh. The coating on the plastic surfaces may help reducing oxygen by higher than 10%.
Lately, U.S. Hercules has launched an innovative packaging material with gas-controlling functions. Thanks to micropores, this new material can control the exchanging of oxygen in bottles with carbon dioxide. It slows down their exchanging rate and thus inhibits fruits/vegetable inhalation and keeps them fresh.
Chinese enterprises are also catching up. China National Produce Preservation Engineering & Technical Research Center in Tianjin has developed a new-type of nanometer preservation film successfully that has passed technical approval. As shown through test by China National Test Center, it complies with state sanitary code in such targets as vapor transmission, transmission coefficient, physical/mechanical strength and lower gas permeability, thus solving the bottleneck of conventional fruits preservation film that lacks variety and mould-proof property.
Aseptic packaging technology
In recent years, aseptic bag and aseptic cup packaging has witnessed a rapid growth. Aseptic bag packaging mainly adopts PET coated film and PE lamination while aseptic cup packaging mainly uses multilayer co-extruded sheets, including PP/PE/EVA/PVDC/PS.
Germany has developed a new technology where coating technology is used to add preservative and antibacterial coating to plastic packaging, which can fully replace preservatives added in food packaging and is very effective for mould resistance in food. This coating technology uses substances such as composite resin and achieves its target via special processes.
Thermostable sterilizing technology is the focus for sterilizing technology. Currently, two types of thermostable sterilizing food packaging are popular in the U.S. market: thermal sterilizing plastic jar and squeezable bottle, both of which are made of PP/EVOH/PP materials. Food packaged with thermal sterilizing plastic jar has the same shelf life as cans and can replace metal cans that preserving food for two years under ambient temperature. Squeezable bottles feature excellent gas preservation and squeezability, and serve as preferred thermal sterilizing packaging for jam and ketchup.
Packaging/processing integrating technology
With accelerated pace in people's daily life, various types of convenience packaging technologies are increasingly winning extensive favor from market. Packaging/processing integrating technology is a typical representative for convenience packaging. Self-heating and self-cooling packaging is a typical example of such technology.
Recently, Shanghai East China Food & Beverage Industrial Research Institute has developed a new generation of self-cooling and self-heating beverage pop-top can, which has won multiple international awards for patent technical achievements. This self-cooling and self-heating beverage pop-top can may cool inside beverage to 10°C-15°C or heat it to 43°C-50°C within 1-2 minutes when pressing the knob outside the can.
New packaging material with special functions
To meet the needs of various packaging functions, package providers are actively developing new packaging materials with special functions. Canadian Toxin Alert is one of the examples, which has developed a packaging material that can detect pathogenic bacteria. Specifically, it can detect four types of pathogenic bacteria: salmonellosis, campylobacter, colibacillosis 0157 and listeriosis. When contacting contaminated food, the packaging material will change color. This packaging material can also detect pests or protein property of gene engineering food.
Besides, France has launched another kind of packaging film manufactured with ordinary PVC material that can detect whether the packaged food contains any transgenosis ingredients. With the help of this specially treated PVC film, it is able to determine whether the contents (such as soybean oil) are processed with transgenosis soybean ingredients, including soybean food containing 5%~10% transgenosis ingredients.
Apart from Canada and France, Japanese Central Chemical Co., Ltd. has lately innovated a dioxin-inhibiting food container. The material itself does not produce any gas (such as hydrogen chloride) that tends to react with dioxin. On the contrary, it can absorb and fix hydrogen chloride gas produced by other wasted materials while burning, thus inhibiting the production of dioxin.
Degradable environmental friendly packaging
Environment-friendliness is the fundamental requirement for sustainable industrial development. It is one of the R&D directions for the packaging sector to further develop degradable packaging materials.
Currently, many countries in the world are developing biodegradable resins to substitute existing plastic packaging. For instance, maize starch resin which is developed by Japan, excels great development potential. Packaging material made with it may be disposed of via burning, biochemical decomposition and intake by insects, thus eliminating the risk of white pollution. Nowadays in Japan, plastic bags made with maize starch resin can compete with plastic bags made with polyolefin plastics in number. Both Australia and USA have developed degradable packaging materials with maize as ingredients as well, and these materials have been applied in Europe and Asia.
As a type of new green packaging material, water-soluble plastic packaging film has attracted increasingly extensive attention. Its main ingredient is low-alcoholysis polyvinyl alcohol. Supported by CNPC (China National Packaging Corporation) Technical Department, Zhuzhou Institute of Technology and Zhaoqing Fangxing Packaging Material Co., Ltd. in Guangdong, China have jointly developed water-soluble film and production equipment. In fact, they have started production and their products will be launched to market soon.
On the other hand, the Material Engineering College in Suzhou University has been working on a research of a type of high-molecular, high-solubility innocuous packaging film which features innocuity and can dissolve quickly in natural environment. This film looks the same as ordinary plastic film from the appearance. However, when it is put in cold water, it quickly shrinks and disappears. As disclosed, different varieties of film can be produced to dissolve in different water temperature depending on dissolving requirements for different products. Indeed, they will not affect water quality when dissolved in water.
Rapid growth of the plastic packaging industry and constant expansion for its application market have both triggered constant technical advancement and development. In turn, constant development of new technologies and new materials has become a main driving force to propel constant expansion of plastic applications.
