Plastic bottles are mainly made of materials such as polyethylene or polypropylene and added with a variety of organic solvents. Plastic bottles widely use polyester (PET), polyethylene (PE), and polypropylene (PP) as raw materials. After adding corresponding organic solvents, they are heated at high temperatures and then blown, extruded, or injection molded through plastic molds. plastic container.
Mainly used for liquid or solid disposable plastic packaging containers such as beverages, food, pickles, honey, dried fruits, edible oil, agricultural and veterinary drugs. Plastic bottles have the characteristics of not easily broken, low cost, high transparency, and food-grade raw materials.
Develop
With the current changes taking place in the world economy, the china’s industrial structure is also in a stage of continuous upgrading. In the current process of industrial upgrading, some low- value-added enterprises have encountered unprecedented challenges and faced various difficulties due to various operating difficulties. Let’s talk about plastic bottle companies in the transformation storm.
There are currently various problems with plastic bottles. Let’s analyze it carefully. First of all, plastic bottles are a labor-intensive industry. Currently, labor costs are rising. For plastic bottle companies, labor costs have become a huge pressure. Secondly, raw material prices continue to rise. Due to rising costs in the market, raw material prices have increased significantly, which has put another layer of pressure on plastic bottle companies. Thirdly, with the European debt crisis and the weakening of the world economy, foreign trade orders for plastic bottles have gradually declined. Many foreign trade companies have moved to the domestic market, which has brought greater pressure to the already fiercely competitive china’s plastic bottle market. Prices The war is becoming more and more fierce, and the profits of enterprises are getting lower and lower.
For plastic bottle manufacturers, under the current various pressures, they should take the road of industrial upgrading, take the road of innovation in the field of plastic packaging, and strive to increase the added value of plastic bottles. Continuous improvement in all aspects of plastic bottle design, production and sales.
Material
Plastic bottles have the characteristics of not easily broken, low cost, high transparency, and food-grade raw materials.
When using plastic products, pay special attention to avoid contact with vinegar, detergents, etc., and avoid direct sunlight, high temperatures, etc. to avoid chemical reactions. In addition, when buying plastic tableware, you should choose plastic products with PE (polyethylene) or PP (polypropylene) markings on the products, few decorative patterns, colorless and odorless, and smooth surfaces.
Preparation method
There are many ways to make polyethylene. The most common one is to polymerize ethylene at a high temperature of 200 to 300°C and a pressure of 1000 to 2000 atmospheres. In polyethylene, no other substances are doped. The polyethylene produced in this way has low density, soft texture, and high stability to sunlight, air, moisture and chemical reagents, so there is no need to add external stabilizers and plasticizers, which are mostly Poisonous or highly toxic.
Features
Plastic bottles are easy to carry, not afraid of falling, acid and alkali resistant, easy to produce, and easy to recycle.
Questions
- When designing squeeze plastic bottles, if the material is high-density polyethylene or polypropylene, the cross-section of the plastic bottle should be rectangular or oval. For bottles made of low-density polyethylene or other flexible plastic bottles, the cross-section should be The cross section is preferably circular. This makes it easier to squeeze the contents out of the plastic bottle. The plastic parts used with plastic bottle mouths are mainly bottle caps and sealers. The design of plastic bottle mouth should focus on how to make the plastic bottle mouth better cooperate with the cap and sealer. The bottom of the plastic bottle is the weakest part of the mechanical properties of the plastic bottle. Therefore, the bottom of plastic bottles is generally designed to be concave; the corners and concavities of plastic bottles are made with larger arc transitions. In order to facilitate the stacking of plastic bottles and increase the stacking stability of plastic bottles, internal grooves should be designed at the bottom of plastic bottles.
- When labels are used on the surface of plastic bottles, the label surface should be smooth. A “frame” can be designed on the surface of the plastic bottle to accurately position the label without movement. During blow molding, the part of the parison that is first contacted by the blow molding always tends to harden first. Therefore, the wall thickness in this part is also larger. The edges and corners are the last contact parts of the parison during inflation, and the wall thickness of these parts is small. Therefore, the edges and corners of plastic bottles should be designed with rounded corners. Changing the surface shape of the plastic bottle, such as making the middle part of the plastic bottle relatively thinner, and adding circumferential grooves or ribs on the surface of the plastic bottle, can improve the stiffness and bending resistance of the plastic bottle. Longitudinal grooves or ribs can eliminate the deflection, sagging or deformation of plastic bottles under long-term load.
- The printed surface of plastic bottles is the part where consumers focus most. The printing surface should be flat and continuous; if the plastic bottle contains handles, grooves, ribs and other structures, care should be taken during design not to cause inconvenience to the printing operation. Oval plastic bottles have higher stiffness, but the manufacturing cost of the mold is higher. Therefore, in order to ensure the stiffness of plastic bottles, in addition to selecting materials with high stiffness, the stiffness and load-bearing strength of plastic bottles must also be enhanced through the shape design of the plastic bottles.
- Since most plastics are notch sensitive, plastic bottles are prone to cracks and cracks at sharp corners, the roots of mouth threads, and necks, so these parts should be designed with rounded corners. For the transfer point of the rectangular plastic bottle, most of the load of the plastic bottle needs to be supported, so locally increasing the wall thickness there will also help improve the stiffness and load-bearing strength of the plastic bottle.
Health information
The main raw material for making beverage bottles is polypropylene plastic, which is non-toxic and harmless. It is used to hold soda and cola- type drinks and has no adverse effects on the human body. However, because plastic bottles still contain a small amount of ethylene monomer, if fat-soluble alcohol, vinegar, etc. are stored for a long time, Organic matter will undergo chemical reactions. Long-term consumption of food contaminated with ethylene can cause dizziness, headache, nausea, loss of appetite, memory loss, etc. In severe cases, it may even lead to anemia. In addition, if you use beverage bottles to hold wine, vinegar, etc., the bottles will be aged by the action of oxygen, ultraviolet rays, etc., releasing more ethylene monomers, which will cause the wine, vinegar, etc. stored in the bottles for a long time to deteriorate and smell. As for beverage bottles that do not contain other liquids and cause accidental injuries, it is recommended that beverage companies indicate the following warning on the bottle packaging:
Bottle bottom logo
“No. 1” PETE
Mineral water bottles, carbonated drink bottles
Do not recycle beverage bottles or fill them with hot water.
Usage: Heat-resistant to 70°C. It is only suitable for holding warm or frozen drinks. It will be easily deformed when filled with high-temperature liquids or heated, and substances harmful to the human body may melt out. Moreover, scientists found that after 10 months of use, Plastic No. 1 may release the carcinogen DEHP, which is toxic to the testicles.
“No. 2” HDPE
Cleaning supplies, bath products
It cannot be cleaned thoroughly and it is recommended not to reuse it.
Usage: They can be reused after careful cleaning. However, these containers are usually difficult to clean and retain the original cleaning supplies, becoming a breeding ground for bacteria. It is best not to recycle them.
“No. 3” PVC
Rarely used for food packaging, it is best not to buy it.
“No. 4” LDPE
Cling film, plastic film, etc.
Do not wrap plastic wrap on the surface of food and heat it in the microwave.
Usage: The heat resistance is not strong. Generally, qualified PE cling film will melt when the temperature exceeds 110°C, leaving some plastic preparations that cannot be decomposed by the human body. Moreover, when food is wrapped in plastic wrap and heated, the fat in the food can easily dissolve harmful substances in the plastic wrap. Therefore, before food is put into the microwave oven, the plastic wrap must be removed first.
“No. 5” PP
Microwave lunch box
When putting it in the microwave, the lid should be removed.
Usage: Microwave safe plastic box that can be reused after careful cleaning. Special attention should be paid to the fact that for some microwave lunch boxes, the box body is indeed made of No. 5 PP, but the lid is made of No. 1 PE. Since PE cannot withstand high temperatures, it cannot be put into the microwave oven together with the box body. For safety reasons, remove the lid from the container before placing it in the microwave.
“No. 6” PS
Bowl instant noodle box, fast food box
Do not use microwave cooking bowls for instant noodles.
Usage: It is heat-resistant and cold-resistant, but cannot be placed in a microwave oven to avoid releasing chemicals due to excessive temperature. And it cannot be used to hold strong acids (such as orange juice ) or strong alkaline substances, because it will decompose polystyrene that is not good for the human body and can easily cause cancer. Therefore, you want to avoid packing hot food in snack boxes.
“No. 7” PC
Other categories: kettles, cups, baby bottles
PC glue meets bisphenol A
Use: A material that is widely used, especially in baby bottles, and is controversial because it contains bisphenol A. Lin Hanhua, associate professor of the Department of Biology and Chemistry at City University of Hong Kong, said that theoretically, as long as bisphenol A is 100% converted into a plastic structure during the production of PC, it means that the product does not contain bisphenol A at all, let alone releases it. However, if a small amount of bisphenol A is not converted into the plastic structure of PC, it may be released and enter food or drinks. So, caution is the rule and take extra care when using this plastic container.
The higher the temperature, the more bisphenol A remains in PC will be released, and the faster it will be released. Therefore, PC water bottles should not be used to hold hot water to avoid increasing the rate and concentration of bisphenol A (if any) release. If your kettle is numbered 7, the following methods can reduce the risk:
- No need to use a dishwasher or dishdryer to clean the kettle.
- Do not heat when using.
- Keep the kettle away from direct sunlight.
- Before first use, wash with baking soda powder and warm water, and dry naturally at room temperature. Because bisphenol A will be released more during the first use and long-term use.
- If the container is dropped or damaged in any way, it is recommended to stop using it, because if there are fine pits on the surface of plastic products, bacteria can easily hide.
- Avoid repeated use of aged plastic utensils.
Waste plastic
As we all know, there are three types of plastic products that are widely used in food packaging: polyvinyl chloride, polyethylene, and polystyrene. It is not harmful to human health if it is used to hold cooking oil for a short period of time. However, using them to hold cooking oil for a long time will contaminate the food and cause harm to the human body.
This is because this type of packaging bottle has the characteristics of high transparency and easy aging. It will be affected by oxygen, ozone, and ultraviolet rays in the air to produce a strong odor. In addition, the polymer itself ages. If it is used to store cooking oil for a long time, it is easy to deteriorate. These food items go bad.
In addition, the element vinyl chloride in PVC is not only toxic, but also easily decomposes in acids and oils to release highly toxic hydrogen chloride and chlorine. Plasticizers added to PVC, such as phthalates, All are toxic, and lead, cadmium and organotin used as stabilizers are all toxic chemicals, are highly toxic, and are easily soluble in grease. Although plastic polystyrene is a low-toxic substance, its component styrene and volatile components ethylbenzene and cumene are toxic and are easily soluble in grease. The plastic polyethylene itself is not toxic. However, after it comes into contact with oil, it can decompose low-molecular compounds. These low-molecular elements will cause toxicity when dissolved in oil.
Molding principle
Plastic bottles are filled in a gun mold and blow molded at a certain temperature and pressure. They can be formed from bottle preforms or directly processed by an injection blow molding machine.
Bottle material development
The process of manufacturing barrier plastic bottles using coating technology has shown a downward trend, and Krones AG of Germany and Tetra Pak of the United States (Tetra Pak, Illinois ) have begun to reduce production scale. Krones and Coca-Cola jointly developed BestPET technology, which coats the outer surface of the bottle with a silicon oxide -containing coating. A spokesman for the company claimed that the technology was outdated due to its high cost and insufficient oxygen barrier properties, and Tetra Pak has also terminated the use of the Glaskin silica plasma coating system applied to the inner walls of PET bottles. Research work.
In addition, the Italian company SIPA has developed a new type of barrier dipping material specifically for PEN bottles. Its trade name is Smart Coat. The process flow is: after the bottle is obtained by blow molding, it goes through the dipping process, and then immediately puts in infrared rays. The bottles are quickly dried in the oven, and then coated a second time, and then the bottles are cured under ultraviolet radiation. A standard dip coating device can process approximately 12,000 plastic bottles per hour. One of the application goals of this PET bottle is to fill carbonated drinks. According to the company, a 0.5-liter capacity, single-purpose dip-coated PET bottle can have a shelf life of up to one year without being dipped. The shelf life of PET bottles is only 7 weeks.
British Innovative Plastics Technology (AFT) has developed a patented water-based flow coating process that can coat the outer surface of a bottle preform made of a special barrier thermoplastic resin. After the bottle preform goes through the coating process, the resin Once cured, the preform can be stretch-blow molded on standard processing equipment. APT Company claims that this coating process improves the CO barrier performance by 3-4 times compared with uncoated PET bottles. Husky is negotiating with APT Company on the transfer of technology to obtain the opportunity to manufacture this kind of PET bottle. The operating license of the coating equipment, which is designed to process 30,000 preforms per hour, said Robert, director of APT. Li said. This technology has been purchased by a certain beverage manufacturer and used to process non-alcoholic beverage packaging bottles.
The Institute of Plastic Processing (IKV) of the University of Aachen in Germany has transferred the plasma coating technology for the inner wall of plastic bottles – PECVD – to Sidel. IKV has also developed a coating technology for the outer wall of plastic bottles, using a 20- 150nm barrier coating, similar to the inner wall coating process, can increase the CO2 of PET bottles by 4 times In terms of barrier performance, the processing cycle of its technical production system device is 15 seconds. The development goals set by the researchers are to reduce the processing cycle to within 10 seconds, use more powerful vacuum pumps, and other improved detection devices.
Crossing the pacific
British explorer David de Rothschild has a new challenge, which is to sail a sailboat made of 12,000 discarded plastic bottles across the Pacific Ocean a journey of more than 17,000 kilometers. More than a month later, the plastic boat finally docked for the first time for supplies. After leaving the port of San Francisco on March 24, the ” Plastiki ” has now arrived at Christmas Island in the Pacific island country of Kiribati. This is also the first time that the six crew members on board have landed. Although made from bundles of discarded plastic bottles, the 18- meter-long Plastiki has proven its ability to withstand wind and waves. The ship is also equipped with laptops, GPS and satellite phones, powered by solar panels and two exercise bikes.
