Waste plastics recycling and utilization technology
There are two types of terracotta pots, one is unglazed terracotta pots, and the other is glazed terracotta pots. Terracotta Pots,Large Terracotta Pots,Small Terracotta Pots,Terracotta Pots Wholesale,Terracotta Pots Online Yixing Yineng Ceramics Co., Ltd , https://www.stflowerpot.com
Synthetic plastics have made great contributions to the promotion of industrial development and improvement of people’s living standards. In the early days of the development of the plastics industry, the chemical stability of synthetic materials was one of the areas that people were very concerned with and focused on. Several decades have passed and its stability has been well resolved. Dramatically, today's stability has become an important cause of hindering its further development. "Farm film" is a good example. Because it is difficult to be biodegraded, it can only be used once. The simplest treatment is to burn it. This not only wastes resources but also causes air pollution.
Industry has three concepts for the recycling and use of plastic products, namely direct use, conversion and utilization, and incineration or biodegradation.
The process of direct use of plastic products is mainly a physical process, that is, the addition of additives or color masterbatch, which is basically a physical mixing process. After plastic chips or plastics are heated and melted, injection molded products, injection blow molded products, or extrusion blown films or extruded cast films are stretched into films. Examples of injection molded products are foam plastic packaging materials (bulk). Examples of injection blow molded products are various plastic packaging bottles. Examples of extrusion blown film formation are multilayer coextruded film products such as heat shrinkable films, cling film, and extruded films. Examples of film formation by extrusion casting are biaxially oriented polypropylene film BOPP and biaxially oriented polyester film BOPET. Since the changes in the materials in the above process are all physical changes, the chemical structure is not changed, which provides convenience for the application of scrap. Therefore, in the production of plastic products, the leftovers in production are generally broken, extruded or granulated or melted and extruded into pellets and re-entered into the production line for continued use. Because of this, crushers and pelletizers are indispensable equipment for the plastics industry. However, there is a limitation to this method, that is, the plastic product should be a single component or the physical properties of the components have little difference, which does not affect secondary physical processing. For example, according to a company in the United States, EVOH, as a PET beer bottle made of sandwich, has a barrier effect that can reach the level of glass bottles and can be completely recycled. However, for most multi-layer composite films or multi-layer co-extruded films, the physical and chemical properties of the materials in each layer are quite different and cannot be directly recycled.
The use of translation as the name suggests is to be used for other purposes. Both chemical and physical methods are included.
Chemical methods can be further divided into two categories: The first method is to use the chemical nature of the polymer to convert the polymer into a small molecule compound or a simple compound. For example, the polyester can be converted into monomer or small molecule compound by hydrolysis, alcoholysis or aminolysis. The hydrolysis reaction is the reverse reaction of the polyester synthesis reaction and can be made into terephthalic acid and ethylene glycol (polyester synthetic raw material monomers); methanol alcoholysis can give methyl terephthalate and ethylene glycol; glycol alcohol The product of the solution is dihydroxyethyl terephthalate; propylene glycol alcoholysis produces oligomers for the synthesis of unsaturated polyesters (for paints or inks) and alkyd resins. Another method is to use the flammability of plastics to generate thermal energy after incineration. These two methods have their advantages and disadvantages. The method of chemical decomposition is high in the utilization of resources, but the process is complicated and the cost is high, thus affecting the recycling of plastic products. Waste gas from incineration, such as the chlorine-containing gas generated after the combustion of PVC (polyvinyl chloride film), is a component of acid rain. In addition, many plastics produce exhaust gas due to incomplete combustion, which is harmful to the environment and human health. Therefore, this This method has been eliminated.
The use of physical conversion is similar to the direct use. The difference is that the latter is used by the manufacturer himself, and the former is used by other manufacturers. The process is also crushing-granulation-extruding (stretching) or injection molding, and if necessary, adding other items.
Here are some examples of successful physical conversion of Styrofoam.
After the sound-absorbing material waste foam is crushed and heated by infrared radiation, its volume is reduced to 1/20 or less; then, it is mixed with a special cement to make a "moke sugar"-like building material. The sound-absorbing effect of this construction material averaged 60%, and noise suppression at certain frequencies could reach more than 90%. This material has now been used as a noise barrier for power stations on walls and ceilings.
The lightweight roofing insulation material is used to crush the waste expanded polystyrene, add the expanded perlite, cement and mortar, stir and mix evenly, maintain the roof for 3 days, naturally dry, and then level the light-weight concrete insulation layer with the cement mortar. The materials made by this method have low production costs, good heat insulation, and cool in winter and cool in summer.
The washed polystyrene foam was washed, crushed to a particle size of 0.1-0.5 cm, and Portland cement No. 425 was added. The volume ratio of the two was 2-3:1, and the additive mass ratio was 1-3%. (Inorganic base), Stir with water, add rosin soap foaming agent, stir and paste, and mold, remove film after 1 hour, water curing for 7 days to make 10cm thick plate, heat transfer coefficient, resistance The compressive strength is good, and the thermal insulation performance can reach the insulation effect of clay brick wall thickness 95cm. When the roof is used, wipe a layer of cement mortar on the board to maintain the water, and then use a bituminous felt as a waterproof layer.
A foamed polystyrene material and a solvent are made into a 5% solution, crushed corn core plant fibers are added, and the mixture is compression molded.
Manufacturing of waterproofing membranes Washes and dries the waste expanded polystyrene and dissolves it with a cheap phenol or chlorocarbon residue. The toughening agent and the film-forming anti-seepage and anti-wear agent are added to form a viscose. After being blown or coated on the surface of the glass cloth, it is dried into a waterproof membrane for the roof or a waterproof membrane for the pipeline. The solvent can be recycled after being cooled.
Metal, wooden doors, windows and glass sealants were prepared by adding 50 kg of waste expanded polystyrene, 200 kg of solvent oil, 40 kg of xylene, 50 kg of xylene to the dissolving tank, stirring, dissolving and removing impurities to obtain a transparent polystyrene rubber. Add 13kS1788 industrial-grade polyvinyl alcohol in another dissolution tank, add 80kg of water, and heat and dissolve at 30-90°C. Add 1kg of dibutyl phthalate and surfactant octylphenol polyoxyethylene ether, and then add appropriate amount of filler bentonite into a paste. The product contains polar substances, which can increase the bonding strength and improve the emulsification properties. Polyvinyl alcohol and bentonite can be evenly dispersed in the paste. Fast drying, good performance, excellent acid and weather resistance.
Used as a bitumen reinforcing agent to add waste foamed polystyrene granules to the molten asphalt to enhance the heat and waterproof effect, and can be used as roofing and road building materials.
Manufacture of anti-leakage and leakage-reducing agent is based on waste-water foamed polystyrene, combined with a small amount of plasticizer, and produced by hot-melting process. The product is plasticized quickly, dry quickly, with good sealing performance, strong adhesion, acid and alkali resistance, anti-aging characteristics. Its waterproof anti-corrosion performance greatly exceeds the commonly used plastic ointment and asphalt ointment, the service life of up to 20 years.
Manufacture of multi-functional resin glue Multi-functional resin glue produced from waste polystyrene foam, with good adhesion, high gloss, strong impact resistance, acid and alkali resistance, etc., used in the production of various glass steel products, can greatly reduce production Cost; In addition, waterproof paint, satin paint, furniture putty glue and other products can also be produced.
Rust-proof rust-proof paint The rust-proof rust-proof paint produced from waste polystyrene foam has low cost and can be directly applied to steel surfaces with certain rust. It has triple functions of anti-infiltration, rust prevention and anti-corrosion. It can also be used for civil use. The surface paint of the furniture.
Problems and Solutions No matter whether it is the conversion of chemical methods or physical methods, they all face a major difficulty. That is, the waste plastics collected are mixed and difficult to identify and classify. On the other hand, they are particularly clean (disposable polystyrene lunch boxes). Difficulties, high operating costs, so manufacturers are not enthusiastic.
Currently there are two main solutions: limiting the production of multi-component plastic products and increasing the level of classified collection and delivery. For example, in Japan, in order to promote the recycling of resources, the “Plastic Bottle Recycling Promotion Conferenceâ€, formed by Japanese beverage manufacturers and plastic bottle manufacturers, recently decided to stop production of colored plastic bottles that would prevent recycling. The used plastic bottles will be collected in accordance with the methods stipulated in the "Container Packaging Recycling Law." After being classified and crushed at the factory, they will be made into fiber products, hangers, and garbage bins. In the past, manufacturers used blue and green plastic bottles to protect beverages such as fruit juices in bottles from ultraviolet radiation. However, in recycling, if colored plastic bottles are mixed in, not only the quality of recycled products will decrease, but also the manual handling will be very "constrained." After all the transparent bottles are used, the way to solve the UV irradiation is to cover all the transparent bottles with labels, and leave needle-like holes in the sewing machine so that they can be easily peeled off. Bottle drawings made of metal such as aluminum will also be replaced with plastic made of the same material as the bottle body.
In addition, delivery is an important factor in determining the economics of material reuse. At present, the foreign technology for childbirth is developing rapidly. Many automated delivery lines have been put into use, and the different types of materials can be handled very accurately. The biggest difficulty comes from composite plastic products.
Biodegradation Because plastic products are not easy to age, they are difficult to be decomposed by microorganisms and cause so-called white pollution. Rather than dealing with it passively, it is better to think at the source. Because of this, the plastics industry attaches great importance to the research and development of biodegradable plastics. At present, there are few varieties that are satisfactory from both the performance and biodegradability. To really achieve industrialization, there is still a long way to go.
Terracotta pots are an excellent choice for most people who are using plants. They can retain their original color. According to the content of clay, they are divided into red, orange, yellow, brown, white, and light gray.
Pottery pots have better drainage than plastic pots and have better air circulation on the side. They are suitable for growing plants that require soil to dry out as soon as possible. If plants are afraid of soil water accumulation, pottery pots can also be used for planting, such as Common tiger skin orchids, aloe vera or succulents, etc.
The Terracotta pot is a relatively durable natural material. It also has a strong decorative effect. After a long time, it will turn into a bronze color. It is very classic. Moreover, the pottery pot has a certain weight and is not easy to tip over like a plastic pot. It also has strong drainage and breathability.