![<?echo $_SERVER['SERVER_NAME'];?>](/template/twentyseventeen/skin/images/header.jpg)
With the improvement of domestic consumption levels, the pace of life of urban and rural residents is accelerating, and travel and tourism are increasing. Concepts and methods of food consumption are quietly changing. Many families try to liberate themselves from the kitchen, reduce fume pollution, reduce household work, and soft canned food. Its characteristics of light weight, convenience, long shelf life, hygiene, easy storage, and easy dismantling have been adapted to people's daily needs and are increasingly welcomed by people. According to experts of the China Food Industry Association, convenience, engineering, functionalization, specialization, and international standardized foods will be the major trends in the development of the food industry in the 21st century. Convenience is mainly for the production of instant noodles, rice, porridge, bread, etc., as well as the convenience of cooked food products such as meat, meat, aquatic products, eggs, and vegetables. Many of these products are filled with semi-cooked food in a laminated film bag, vacuumed, sealed and sterilized at 125° C. for 45 to 70 minutes. No additives are needed to maximize the color, aroma, taste and nutritional value of the food. Popular with consumers.
According to reports, the output of cooked meat and poultry meat products in China is currently only 3 million tons, accounting for 6% of the total meat production, which is far from the level of more than 50% of cooked meat products in developed countries. If you can catch up, not only can the meat products add value significantly, but the flexible packaging that they use will also be greatly developed. Experts predict that bagged meat products in China will grow at a rate of 20%/a in the next few years, indicating that the market for cooking and compounding bags is promising.
At present, more than 300 composite film production lines have been established throughout the country, many of which are foreign-funded enterprises, and some have even made composite films into the international market. Commonly used composite film packaging materials are PE, PP, PET, PA, PVDC, PVC, PVA, PT (also known as cellophane), aluminum foil or aluminized film, plated silicon oxide film. In addition to the properties of the selected film, the properties of the composite film packaging material also play a crucial role in the performance of the compound adhesive.
Retort bag with temperature rating can have: (1) boiling water resistant to 100 °C; (2) resistant to 121 °C retort sterilization (121 °C sterilization 40min.); (3) resistant to 135 °C high temperature cooking sterilization (135 °C sterilization 20 - 30min.). The latter is aseptically packaged. Because the packaged food is completely free of bacteria and there is no air, the purpose of long-term preservation of food under non-refrigerated conditions can be achieved. When it is eaten, it can be cold, hot, and easy to use, saving energy when it is stored. Many of the unique properties of polyurethane adhesives make them dominant in composite film adhesives. However, the fatal weakness of general-purpose polyurethane adhesives is poor temperature resistance, low adhesion to metal, and can not be used as cooking adhesive composites without modification. The latter performance requirements:
(1) High adhesiveness to various materials To achieve freshness preservation and long-term storage, cooking bags need to be composed of multiple layers. The outer layer is made of polyester film with high mechanical strength, gas barrier, moisture resistance, fragrance protection, heat resistance, transparency, cold resistance, water resistance and oil resistance. The middle layer is made of aluminum foil or PVDC with excellent barrier properties and high and low temperature resistance. Uses polypropylene, which is excellent in hygiene, oil resistance, chemical resistance, and heat sealability. Composite adhesives should have good adhesion to them.
(2) Fast curing speed The curing time of the two-component polyurethane adhesive can be shortened at a certain temperature and the initial tackiness thereof can be improved, which will help improve the productivity of the composite film and create a good economic benefit. High-viscosity composite adhesives still need to adapt to the rapid development of high-speed composite machines.
(3) The high temperature resistance needs to withstand the high temperature retort sterilization (previously mentioned) under heating and pressure during food processing, and the instantaneous high temperature (220°C) during bag sealing.
(4) Anti-Media Erosion Food contains salt, acid, spicy, spices, alcohol, water, sugar, sulfur, fatty acids, oils, and proteins. Its characteristics are different, but there is a common nature that may penetrate through the inner layer of the composite film. The adhesive layer, which acts as a corrosive agent, causes the package to delaminate, rupture, and fail. For this reason, the adhesive must have the ability to withstand the erosion of the above substances and always maintain sufficient adhesive peel strength.
(5) Transparency High transparency aims at improving the shelf effect.
(6) Although the harmless composite adhesive is not in direct contact with food, small molecules in the adhesive may migrate into the food during the high-temperature cooking process. For this reason, small molecules must be minimized during production or recombination.
It is more difficult to achieve the above six requirements at the same time. Because the performance of domestic adhesives can not meet the increasingly demanding requirements of the compounding process, the adhesives used in cooking bags are basically relied on imports, which not only consumes large amounts of foreign exchange, but also hinders the rapid development of the food industry. In view of this, the Dawning Chemical Research Institute researched and developed such products and achieved certain results. This is outlined below.
The hospital analyzed the reasons for the poor temperature resistance and poor adhesion to aluminum of general polyurethane composite adhesives. Molecular structure design, the introduction of corresponding groups, and the synthesis process were studied. Through small trials and expansion tests, we have achieved satisfactory results. The main technical performance indicators achieved by the products are listed in Table 1. The finished product obtained by the extended trial was tested on an imported composite machine (Japan Fuji 150 interference machine) at a vehicle speed of 80 m/min, and the resulting composite bag (PET/A1/CPP, PET/BOPA/CPP) was installed 40 °C saturated brine, according to GB10004-88 retort test (127 °C, 45min), complete packaging bags, no pinholes, no delamination phenomenon. Before cooking, T-type adhesive peel strength was greater than 5N/15mm, and after cooking, they were all greater than 8.6N/15mm. Some could not be peeled and the substrate was destroyed (see Table 2). With tomato sauce, chili sauce, 3% acetic acid (1:1:1, quality) or packaging bag with salad oil, tomato sauce, 3% acetic acid (1:1:1, quality), or with 4.2% acetic acid , Cooking tests were conducted separately, and there was no delamination phenomenon in the packaging bags. The test results show that the developed adhesive can compound high-temperature cooking food bags, and is resistant to the contents, achieving the performance of imported similar products. Toxicity is the most avoidable of food packaging bags. Samples on the machine complex packaging bags tested by the hospital, no small molecules precipitated, sent to the Henan Provincial Health and Epidemic Prevention Station in accordance with the national standard methods to detect compliance with health standards (GB9683-88) (Henan Province Health Supervision Document Shizi 2001-069).
The hospital wholeheartedly wishes to cooperate with the composite packaging industry to conduct application trials, improve and improve product performance, improve the production process, convert scientific research achievements into productivity, and produce domestically produced national brands.
Source: Packaging magazine Author: Cui Tao Ye Qingxuan