The polymer industry is the recycling of these. "Polymer Recycling in Europe: New and Proven Solutions". Equipment for starting a mini-factory

25.11.2019

11.08.2015 16:09

Waste classification

Waste is generated during the processing of polymers and the manufacture of products from them - this is technological waste, partially returned to the process. What remains after the use of plastic products - various films (greenhouse, construction, etc.), containers, household and large-scale packaging - is household and industrial waste.

Technological waste is subjected to thermal action in the melt, and then, during crushing and agglomeration, to intense mechanical stress. In the bulk of the polymer, the processes of thermal and mechanical degradation proceed intensively with the loss of a number of physical and mechanical properties and, with repeated processing, can adversely affect the properties of the product. So, when returning to the main process, as usual, 10-30 percent of secondary waste, a significant amount of material goes through up to 5 cycles of extrusion and crushing.

Household and industrial waste is not only recycled several times at high temperatures, but also exposed to long-term exposure to direct sunlight, oxygen and moisture in the air. Greenhouse films can also come into contact with pesticides, pesticides, iron ions, which contribute to the degradation of the polymer. As a result, a large amount of active compounds accumulate in the polymer mass, accelerating the breakdown of polymer chains. The approach to recycling of such different wastes should accordingly be different, taking into account the history of the polymer. But first, let's look at ways to reduce the amount of waste generated.

Reducing the amount of process waste

The amount of technological waste, primarily start-up waste, can be reduced by using heat stabilizers before stopping the extruder or injection molding unit, in the form of the so-called stop concentrate, which many people forget or neglect. When the equipment stops for a simple material in the extruder barrel or injection molding machine, it is under the influence of high temperature for quite a long time when cooling and then heating the barrel. During this time, the processes of cross-linking, decomposition and burning of the polymer actively proceed in the cylinder, products accumulate, which, after start-up, come out for a long time in the form of gels and colored inclusions (burns). Thermal stabilizers prevent these processes, making it easier and faster to clean the equipment after start-up. To do this, before stopping, 1-2 percent of the stop concentrate is introduced into the cylinder of the machine for 15-45 minutes. to a stop at the rate of displacement of 5-7 cylinder volumes.

Processing (extrusion) additives that increase the manufacturability of the process also make it possible to reduce the amount of waste. By their nature, these additives, for example, Dynamar from Dyneon, Viton from DuPont, are derivatives of fluororubbers. They are poorly compatible with basic polymers and in places of greatest shear forces (dies, sprues, etc.) are precipitated from the melt onto the metal surface, creating a near-wall lubricating layer on it, along which the melt slides during molding. The use of the processing additive in the smallest quantities (400-600 ppm) allows solving numerous technological problems - reducing the torque and pressure on the extruder head, increasing productivity while reducing energy costs, eliminating appearance defects and reducing the extrusion temperature of polymers and compositions sensitive to elevated temperatures, increase product smoothness, produce thinner films. In the manufacture of large-sized or thin-walled molded products of complex shape, the use of an additive can improve pourability, remove surface defects, solder lines and improve the appearance of the product. All this in itself reduces the proportion of marriage, i.e. amount of waste. In addition, the processing additive reduces the sticking of carbon deposits on the die, fouling of sprues, and has a washing effect, i.e. reduces the number of stops to clean equipment, and therefore the amount of start-up waste.

An additional effect is the use of cleaning concentrates. They are used when cleaning casting and film equipment for a quick transition from color to color without stopping, most often in a ratio of 1:1-1:3 with polymer. This reduces the amount of waste and time spent on color changes. The composition of cleaning concentrates produced by many domestic (including Klinol, Klinstyr from NPF Bars-2, Lastik from Stalker LLC) and foreign manufacturers (for example, Shulman - Poliklin ”), as a rule, soft mineral fillers and surface-active detergent additives are included.

Reducing the amount of household and industrial waste.

There are various ways to reduce the amount of waste by increasing the service life of products, primarily films, through the use of thermal and light stabilizing additives. When extending the service life of the greenhouse film from 1 to 3 seasons, the amount of waste to be disposed of decreases accordingly. To do this, it is enough to introduce small amounts of light stabilizers into the film, no more than half a percent. Stabilization costs are low, and the effect of film recycling is significant.

The way back is to accelerate the degradation of polymers by creating photo- and biodegradable materials that quickly degrade after use under the action of sunlight and microorganisms. To obtain photodegradable films, comonomers with functional groups that promote photodegradation (vinyl ketones, carbon monoxide) are introduced into the polymer chain, or photocatalysts are introduced into the polymer as active fillers that promote the breaking of the polymer chain under the action of sunlight. Dithiocarbamates, peroxides or oxides of transition metals (iron, nickel, cobalt, copper) are used as catalysts. The Institute of Water Chemistry of the National Academy of Sciences of Ukraine (V.N. Mishchenko) developed experimental methods for the formation of nanosized cluster structures containing metal and oxide particles on the surface of titanium dioxide particles. The rate of decomposition of films increases 10 times - from 100 to 8-10 hours.

The main directions for obtaining biodegradable polymers:

synthesis of polyesters based on hydroxycarboxylic (lactic, butyric) or dicarboxylic acids, however, so far they are much more expensive than traditional plastics;

plastics based on reproducible natural polymers (starch, cellulose, chitosan, protein), the raw material base of such polymers can be said to be unlimited, but the technology and properties of the resulting polymers do not yet reach the level of the main multi-tonnage polymers;

making industrial polymers (polyolefins in the first place, as well as PET) biodegradable by compounding.

The first two directions require large capital expenditures for the creation of new industries; the processing of such polymers will also require significant changes in technology. The easiest way is compounding. Biodegradable polymers are obtained by introducing biologically active fillers (starch, cellulose, wood flour) into the matrix. So, back in the 80s, V.I. Skripachev and V.I. Kuznetsov from ONPO Plastpolimer developed starch-filled films with an accelerated aging period. Unfortunately, the relevance of such material then was purely theoretical, and even now it has not received wide distribution.

Waste recycling

You can give the polymer a second life with the help of special complex concentrates - recyclers. Since the polymer undergoes thermal degradation at each stage of processing, photo-oxidative degradation during the operation of the product, mechanical degradation during grinding and agglomeration of waste, degradation products accumulate in the mass of the material, and a large amount of active radicals, peroxide and carbonyl compounds are contained, which contribute to further decomposition and cross-linking of polymer chains. Therefore, the composition of such concentrates includes primary and secondary antioxidants, thermal and light stabilizers of the phenolic and amine type, as well as phosphites or phosphonites, which neutralize active radicals accumulated in the polymer and decompose peroxide compounds, as well as plasticizing and combining additives that improve physical and mechanical properties. properties of the recycled material and pull them up more or less close to the level of the virgin polymer.

Complex additives of the Siba company. Ciba, Switzerland, offers a family of complex stabilizers for the processing of various polymers - high-density polyethylene, HDPE, PP: Recyclostab / Recyclostab and Recyclosorb / Recyclossorb. They are tablet mixtures of various photo- and thermal stabilizers with a wide range of melting temperatures (50-180°C), suitable for input into processing equipment. The nature of the additives in the Recyclostab composition is common for polymer processing - phenolic stabilizers, phosphites and processing stabilizers. The difference lies in the ratio of components and in the selection of the optimal composition in accordance with a specific task. "Recyclossorb" is used when light stabilization plays an important role, i.e. the resulting products are operated outdoors. In this case, the proportion of light stabilizers is increased. The input levels recommended by the firm are 0.2-0.4 percent.

"Recyclostab 421" is specially designed for processing and thermal stabilization of waste films of LDPE and mixtures with a high content of it.

"Recyclostab 451" is designed for the processing and thermal stabilization of PP waste and mixtures with a high content of it.

Recyclostab 811 and Recyclossorb 550 are used to extend the life of recycled products used in sunlight, so they contain more light stabilizers.

Stabilizers are used in the production of molded or film products from secondary polymers: boxes, pallets, containers, pipes, non-critical films. They are produced in granulated, non-dusting form, without a polymer base, pressed granules with a melting range of 50-180°C.

Complex concentrates of the Bars-2 company. For the processing of secondary polymers, SPF Bars-2 produces complex polymer-based concentrates containing, in addition to stabilizers, also combining and plasticizing additives. Complex concentrates "Revtol" - for polyolefins or "Revten" - for high-impact polystyrene, are introduced in an amount of 2-3 percent during the processing of secondary plastics and, thanks to a complex of special additives, prevent thermal-oxidative aging of secondary polymers. Concentrates facilitate their processing due to the improvement of the rheological characteristics of the melt (increased MFR), increase the strength characteristics of finished products (their ductility and resistance to cracking) compared to products made without their use, facilitate their processing as a result of an increase in the manufacturability of the material (reduced torque and drive load). When processing a mixture of secondary polymers "Revtol" or "Revten" improve their compatibility, so the physical and mechanical properties of the resulting products also increase. The use of "Revten" allows you to increase the properties of the secondary UPM to the level of 80-90 percent of the properties of the original polystyrene, preventing the appearance of defects.

Now the development of a complex concentrate for the processing of recycled PET is very relevant. The main scourge here is the yellowing of the material, the accumulation of acetaldehyde, and the decrease in the viscosity of the melt. Known additives Western firms - "Siba", "Clarianta", allowing to overcome yellowing and improve the processability of the polymer. However, in the West and we have a different approach to the use of secondary PET. Whereas 90 percent of it is used to make polyester fibers or technical products, and additives for this purpose are well developed, our processors are striving to bring recycled PET back into the mainstream - molding and blowing preforms and bottles, or making films and sheets using flat slot extrusion. In this case, the target properties of the polymer, which must be affected, are somewhat different - manufacturability, formability, transparency, and the formulation of complex additives must meet the goal.

Waste classification

Wastes are generated during the processing of polymers and the manufacture of products from them - these are technological wastes, partially returned to the process. What remains after the use of plastic products - various films (greenhouse, construction, etc.), containers, household and large-scale packaging - is household and industrial waste.

Technological waste is subjected to thermal action in the melt, and then, during crushing and agglomeration, also to intense mechanical stress. In the bulk of the polymer, the processes of thermal and mechanical degradation proceed intensively with the loss of a number of physical and mechanical properties and, with repeated processing, can adversely affect the properties of the product. So, when returning to the main process, as usual, 10-30 percent of secondary waste, a significant amount of material goes through up to 5 cycles of extrusion and crushing.

Reducing the amount of process waste

Processing (extrusion) additives that increase the manufacturability of the process also make it possible to reduce the amount of waste. By their nature, these additives, for example, Dynamar from Dyneon, Viton from DuPont, are derivatives of fluororubbers. They are poorly compatible with basic polymers and in places of greatest shear forces (dies, sprues, etc.) are precipitated from the melt onto the metal surface, creating a near-wall lubricating layer on it, along which the melt slides during molding. The use of a processing additive in the smallest quantities (400-600 ppm) allows solving numerous technological problems - reducing the torque and pressure on the extruder head, increasing productivity while reducing energy costs, eliminating appearance defects and reducing the extrusion temperature of polymers and compositions sensitive to elevated temperatures, increase product smoothness, produce thinner films. In the manufacture of large-sized or thin-walled molded products of complex shape, the use of an additive can improve pourability, remove surface defects, solder lines and improve the appearance of the product. All this in itself reduces the proportion of marriage, i.e. amount of waste. In addition, the processing additive reduces the sticking of carbon deposits on the die, fouling of sprues, and has a washing effect, i.e. reduces the number of stops to clean equipment, and therefore the amount of start-up waste.

An additional effect is the use of cleaning concentrates. They are used in the cleaning of casting and film equipment for a quick transition from color to color without stopping, most often in a ratio of 1:1-1:3 with polymer. This reduces the amount of waste and time spent on color changes. The composition of cleaning concentrates produced by many domestic (including Klinol, Klinstyr from NPF Bars-2, Lastik from Stalker LLC) and foreign manufacturers (for example, Shulman - Polyclin ”), as a rule, soft mineral fillers and surface-active detergent additives are included.

Reducing the amount of household and industrial waste.

The main directions for obtaining biodegradable polymers:
synthesis of polyesters based on hydroxycarboxylic (lactic, butyric) or dicarboxylic acids, however, so far they are much more expensive than traditional plastics;
plastics based on reproducible natural polymers (starch, cellulose, chitosan, protein), the raw material base of such polymers can be said to be unlimited, but the technology and properties of the resulting polymers do not yet reach the level of the main multi-tonnage polymers;
making industrial polymers (polyolefins in the first place, as well as PET) biodegradable by compounding.

Waste recycling

It is possible to give the polymer a second life with the help of special complex concentrates - recyclers. Since the polymer undergoes thermal degradation at each stage of processing, photo-oxidative degradation during the operation of the product, mechanical degradation during grinding and agglomeration of waste, degradation products accumulate in the mass of the material, and a large amount of active radicals, peroxide and carbonyl compounds are contained, which contribute to further decomposition and cross-linking of polymer chains. Therefore, the composition of such concentrates includes primary and secondary antioxidants, thermal and light stabilizers of the phenolic and amine type, as well as phosphites or phosphonites, which neutralize active radicals accumulated in the polymer and decompose peroxide compounds, as well as plasticizing and combining additives that improve physical and mechanical properties. properties of the recycled material and pull them up more or less close to the level of the virgin polymer.

Complex additives of the Siba company. Ciba, Switzerland, offers a family of complex stabilizers for the processing of various polymers - LDPE, HDPE, PP: Recyclostab / Recyclostab and Recyclosorb / Recyclossorb. They are tablet mixtures of various photo- and thermal stabilizers with a wide range of melting temperatures (50-180°C), suitable for input into processing equipment. The nature of the additives in the Recyclostab composition is common for polymer processing - phenolic stabilizers, phosphites and processing stabilizers. The difference lies in the ratio of components and in the selection of the optimal composition in accordance with a specific task. "Recyclossorb" is used when light stabilization plays an important role, i.e. the resulting products are operated outdoors. In this case, the proportion of light stabilizers is increased. Input levels recommended by the firm are 0.2-0.4 percent.

"Recyclostab 421" is specially designed for processing and thermal stabilization of waste films of LDPE and mixtures with a high content of it.

"Recyclostab 451" is designed for the processing and thermal stabilization of PP waste and mixtures with a high content of it.

Recyclostab 811 and Recyclossorb 550 are used to extend the life of recycled products used in sunlight, so they contain more light stabilizers.

Complex concentrates of the Bars-2 company. For the processing of secondary polymers, SPF Bars-2 produces complex polymer-based concentrates containing, in addition to stabilizers, also combining and plasticizing additives. Complex concentrates "Revtol" - for polyolefins or "Revten" - for high-impact polystyrene, are introduced in the amount of 2-3 percent during the processing of secondary plastics and, thanks to a complex of special additives, prevent thermal-oxidative aging of secondary polymers. Concentrates facilitate their processing due to the improvement of the rheological characteristics of the melt (increased MFR), increase the strength characteristics of finished products (their ductility and resistance to cracking) compared to products made without their use, facilitate their processing as a result of an increase in the manufacturability of the material (reduced torque and drive load). When processing a mixture of secondary polymers "Revtol" or "Revten" improve their compatibility, so the physical and mechanical properties of the resulting products also increase. The use of "Revten" allows you to increase the properties of the secondary UPM to the level of 80-90 percent of the properties of the original polystyrene, preventing the appearance of defects.

Now the development of a complex concentrate for the processing of recycled PET is very relevant. The main scourge here is the yellowing of the material, the accumulation of acetaldehyde, and the decrease in the viscosity of the melt. Known additives Western firms - "Siba", "Clarianta", allowing to overcome yellowing and improve the processability of the polymer. However, in the West and we have a different approach to the use of secondary PET. Where 90 percent of it is used to make polyester fibers or technical products, and the additives for this purpose are well developed, our processors are keen to bring recycled PET back into the mainstream - preforms and bottles by injection molding and blowing, or films and sheets by flat slot extrusion. In this case, the target properties of the polymer, which must be affected, are somewhat different - manufacturability, formability, transparency, and the formulation of complex additives must meet the goal.

As part of the CREON Group

Polymer recycling, which is so developed in European countries, is still in its infancy in Russia: separate waste collection has not been established, there is no regulatory framework, there is no infrastructure, and there is no consciousness among the majority of the population. However, market players look to the future with optimism, pinning their hopes on the Year of Ecology, which was announced in the country in 2017 by presidential decree.

The third international conference "Polymer Recycling 2017", organized by INVENTRA, took place in Moscow on February 17. The partners of the event were Polymetrix, Uhde Inventa-Fischer, Starlinger Viscotec, MAAG Automatik, Erema and Moretto; support was provided by Nordson, DAK Americas and PETplanet. The information sponsor of the conference is the Polymer Materials magazine.

“Now the situation is not inspiring, but its improvement is a matter of time,” said Sergey Stolyarov, Managing Director of CREON Group, in his welcoming speech. – With high prices for primary raw materials, the demand for recycled polymers and products from them will grow. At the same time, the emergence of domestic raw materials will shift the structure of primary PET consumption towards fibers and films. In this regard, the use of secondary polymers becomes especially promising.”

At the end of 2016, the global collection of PET for recycling amounted to 11.2 million tons, said Helen McGee, consultant of PCI Wood Mackenzie. The main share fell on the countries of Asia - 55%, in Western Europe 17% of the world volume was collected, in the USA - 13%. According to the expert's forecast, by 2020 the collection of PET for recycling will exceed 14 million tons, and in percentage terms the collection level will reach 56% (now 53%). The main growth is expected at the expense of Asian countries, in particular, China.

At the moment, the highest level of collection is observed in China, it is 80%, and other Asian countries have reached approximately the same figure. According to Ms. McGee, out of PET collected in 2016 (and this, we recall, 11.2 million tons), production losses amounted to 2.1 million tons, respectively, 9.1 million tons of flakes were obtained. The main direction of further processing is fibers and threads (66 %).

By 2025, 60% of household waste will be recycled in Europe, in 2030 this figure will grow to 65%. Such amendments are planned to the Waste Framework Directive, said Kaspars Fogelmanis, Chairman of the Board of Directors of Nordic Plast. Now the level of recycling is much lower - in Latvia, for example, it is only 21%, on average in Europe - 44%. At the same time, the volumes of plastic packaging produced in the Baltic States are growing every year, the most common recyclable polymers are LDPE, HDPE and PP film.

In Russia, in 2016, the consumption of recycled PET (rePET) amounted to about 177 thousand tons, of which 90% fell to domestic collection. According to Konstantin Rzayev, Chairman of the Board of Directors of EcoTechnologies Group, almost 100% of imports fell on PET flakes for the production of polyester fiber. The largest supplier countries are Ukraine (more than 60%), as well as Kazakhstan, Belarus, Azerbaijan, Lithuania and Tajikistan.

Konstantin Rzayev noted that last year the collection rate for the first time exceeded 25%, and this allows us to speak about the emergence in Russia of a full-fledged industry that is already of interest for investment. Today, the main consumer (62% of the total volume) and the price driver is still the recycled PET fiber segment. But changes in legislation and the trend towards the priority use of recycled materials as part of the sustainable development strategies of multinational consumer goods companies provide fertile ground for the development of another key segment of rePET consumption - bottle-to-bottle.

Over the past year, there were no new large-scale productions consuming rePET, but its use in the sheet segment is gradually growing. However, already in 2017, it is expected to open new recycled PET fiber production facilities and expand existing ones, which, together with the ruble exchange rate, will be the main factor influencing the market balance and prices for rePET.

However, there are many other areas - still undeveloped, but quite promising, where recycled PET is also in demand. According to ARPET Honorary President Viktor Kernitsky, these are threads for furniture fabrics, car upholstery and various types of geosynthetics, foamed materials for heat and sound insulation, sorption materials for wastewater treatment, as well as bitumen reinforcing fibers for road construction. According to the expert, there are many new processing technologies and applications, and the goal of state policy should not be to limit the use of PET, but to collect and rationally use its waste.

The topic was continued by Lyubov Melanevskaya, Executive Director of the RusPEC association, who spoke about the first results of the introduction of extended producer responsibility (EPR) in Russia. It entered into force in 2016, its goal is to create a constant, solvent and growing demand for the recycling of product and packaging waste. After a year, it is already possible to draw some conclusions, the main of which is that there are a number of problems due to which the mechanism for the implementation of the RPR often simply does not work. As Ms. Melanevskaya said at the conference, there is a need to change and supplement the existing regulation. In particular, when declaring goods, including packaging, manufacturers encountered a discrepancy between the codes for the packaging of goods and the codes specified in the adopted regulatory acts, as a result of which many manufacturers and importers were unable to file declarations, because. did not find themselves in regulation. The solution was the rejection of codes and a proposal to switch to the identification of packaging by materials.

In the future, according to RusPEC, it is necessary to adopt a single end-to-end terminology for all elements of the RPR and determine unambiguous, understandable and transparent conditions for concluding contracts with waste management operators. On the whole, the association supports the law on EPR as necessary and positive for the industry.

When introducing and popularizing PET recycling in the country, the availability of modern technologies (as a rule, they are provided by foreign companies) is of great importance. Thus, Polymetrix offers modern integrated solutions for the recycling of PET, including its own SSP technology, for recycling PET bottles into food-grade PET bottles. Now there are 21 such lines in the world, said Danil Polyakov, regional sales manager. The technology is aimed at the premium market and involves the processing of bottles into pellets for food containers. The first step is the wash, where paper fibers and surface contaminants are completely removed, as well as labels and glue. Next, the bottles are crushed into flakes, which are sorted by morphology and color. Then there is the production of granules and then - the final complete purification and restoration of the characteristics of the polymer at the SSP stage.

Viscotec offers its customers the technology to convert PET bottles into sheets, says company spokesman Gerhard Osberger. For example, the viscoSTAR and deCON solid phase polycondensation reactors are designed to purify and increase the viscosity of PET pellets and flakes. They are used after the granulator, before the production extrusion equipment or as a stand-alone unit. The ViscoSHEET line is capable of producing tape made from 100% recycled PET and fully food grade.

Christoph Wjoss, a representative of Erema, spoke about the in-line production of food-grade plastic bottles from PET flakes. The VACUREMA® inline system allows you to process flakes directly into finished thermoforming sheet, bottle preform, finished packaging tape or monofilament.

Summing up the results of the conference, its participants identified the main factors hindering the development of polymer recycling in Russia. The main one they called the lack of regulatory documents:

“Nevertheless, there is one more factor that we cannot but take into account - this is public consciousness,” says the director of the conference, Rafael Grigoryan. “Unfortunately, our mentality today is such that the separate collection of waste is perceived more as pampering than as the norm. And no matter what progress we see in other areas, it is necessary first of all to change the thinking of our fellow citizens. Without this, even the most modern infrastructure will be useless.”

The 20th century is considered the century of steel and non-ferrous metals. Aluminum, copper, iron alloys could be found everywhere - in bed headboards, bridges, mechanisms of all types, cladding panels. However, as a result of mechanical processing, 50–80% of the melted material went into chips. Experts pinned great hopes on the chemical industry associated with a decrease in material consumption. And yet, despite the growth in the use of polymers, the results of the industry by the 80s were about the same: half of the resources were wasted.

Obviously, the apparent availability of polymers is an illusion. The raw material used for their manufacture is a natural rarity. Access to its sources is a daily and invariable cause and cause of trade, diplomatic and other wars. The geography of extraction of natural resources is increasingly shifting to places not so remote. Therefore, today they are increasingly talking about the need to introduce resource-saving business models.

The uniqueness of the technological methods of modern chemical production lies not only in the ability to synthesize materials that successfully replace metal, paper or wood.

Most of today's industrial complexes of developed economies are able to recycle obsolete polymer products into new ones that are in demand by the user.

Recycled plastics

The main classes of polymers include:

polyethylenes,
polypropylenes,
PVC,
polystyrenes (including copolymers - ABS plastics),
polyamides,
polyethylene terephthalate.

Products that are complex in composition are first of all separated. For physical cleaning, various mechanisms are used - vacuum, thermal, cryogenic.

The most common and economically justified technologies are flotation and dissolution.

In the first case, the plastic is crushed, immersed in water. There are also added compounds that affect the ability of various plastics to absorb moisture. After separation, separated polymers are obtained.

In the second method, complex compressed parts are crushed and successively exposed to various solvents. To restore materials in their pure form, the resulting compounds are exposed to water vapor. As a result of a precisely executed process, finished products of a high degree of purity are obtained. Further processing of various plastics may have its own characteristics associated with the individual properties of polymers.

Polyethylene of high and low pressure (LDPE and HDPE).

The group of these compounds is also called polyolefins. They have found wide application in all types of industry, medicine, and the agricultural sector. PE are thermoplastics - materials suitable for remelting. This feature is successfully used by the industry, processing its own technological waste in order to reduce operating costs.

The complexity of the recycling of used plastic is due to the partial destruction of its surfaces caused by sunlight. Products obtained by the usual processing of products: grinding, mechanical cleaning, remelting, are not of high quality. Most often, such polyethylene is used for the manufacture of auxiliary household equipment.

Secondary polyethylene, which has undergone chemical modification, turns out to be more perfect. Various additives placed in the polymer melt bind the changed molecular units and even out the structure of the substance. Dicumyl peroxide, wax, lignins, slates are used as modifiers. Additives of certain types lead to a change in certain properties of recycled PE. Combining them allows you to get a material with the necessary parameters.

Polypropylene (PP)

This material is rarely recycled. Most often, plastic has one life, despite its excellent consumer characteristics that allow the use of the polymer in the food industry. Despite good remeltability, the high cost of maintaining hygiene deters processors. Nevertheless, in the United States every fifth ton of PP is reused.

According to chemists, PP can withstand no more than four remelts. With each heating, a certain amount of deformed molecular units accumulates, affecting the physical characteristics of the material. Secondary granules are easily processed in extruders and injection molding machines.

Recycled plastic does not require special modification. Its parameters are comparable with the original material, only slightly reduced frost resistance. Again, the polymer finds use in battery cases, garden tools, containers and films.

Polyvinyl chloride PVC

The material is used for the manufacture of linoleums, finishing films. Plastic is subject to thermal degradation. At temperatures above 100°, the oxidation of macromolecules begins to pick up speed, leading to a deterioration in the thermoplastic properties of the material.

The technology of extrusion using recycled PVC requires special preparation: the initial raw material mixture in the melt may be inhomogeneous. Solid modifications of PVC containing recycled plastic will have uneven internal stress. In order to minimize negative impacts, dry processing of granules in compactors is carried out before extrusion. As a result of this operation, fibers are formed that reinforce the walls of new products.

More often recycled polyvinyl chloride is used to obtain plastisols, vinyl plastics. Pastes, solutions, injection molded products are obtained from these materials. Among the new technologies, multi-layer casting is gaining popularity. A feature of the method is the production of a multi-component sheet, each layer of which has different characteristics.

The outer surface of the composite is formed by a high-quality polymer, the inner layers are recycled plastic.

Polystyrene (UPS, PSM) ABS plastic

Various types of polystyrene are recycled in one mass - impact-resistant modifications, copolymers, acrylonitrile butadiene styrene. The versatility of products made from PS is often the reason why industrialists refuse to process it. The price of cleaning, sorting, modification is too high.

Prospects for plastics recycling.

In developed economies, the share of plastic processing reaches 26% of the generated amount - up to 90 million tons. At the same time, the volume the world market is 600 billion dollars. The domestic segment of polymer recycling looks somewhat more modest: 5.5 million tons. According to experts, the demand of the Russian industry for monomers and high-grade modified thermoplastics significantly exceeds their supply. The presence of these two factors leads to an increase in national capacities for polymer processing. Moreover, the growth rates of industrial volumes in this area are ahead of European ones. Existing market trends are taken into account in government forecasts. The priority of re-equipment of the processing industry is laid down in the twenty-year sectoral plan for the development of gas and petrochemistry.

The widespread use of polymeric material implies the timely disposal of raw materials and secondary processing for subsequent use. To carry out these actions, the following types of equipment are required: agglomeration devices, crushing mechanisms and granulation devices.

Environmental conditions dictate the need for waste-free production of polymer-type goods, in order not to pollute the ecology of the surrounding space. For this reason, industrial production annually increases production capacity due to the secondary and subsequent processing of polymers.

Agglomerators, as a result of functioning, transform the polymer into an agglomerate. This device is a mechanism for processing used polymer products. The process occurs due to the sintering of finely crushed particles into granular components. The resulting granulated raw material is reused in the production of polymer products, in the form of a main or auxiliary element.

Polymer processing technology

The processing of polymers involves preliminary operations in the sector of the unit, with the help of appropriate knives. Further, the processing of polymers continues with heat treatment (under the influence of a high temperature regime, frequent contact of crumbs of polymeric raw materials occurs).

Upon receipt of operating temperatures up to one hundred degrees, the container is filled with water. The created liquid medium promotes the formation of agglomerate. The formed granular components, through a special gate valve, are transferred to the tank chamber for temporary storage and subsequent removal.

Granulators are devices that are used for. Granular processing of polymers is achieved by micro-crushing operations and the formation of the same type of polymer or plastic granules. The resulting granulate is used as a feedstock in the manufacture of molded and extruded polymeric substances.

As a rule, granulators are a rather complex structure, consisting of several synchronized installations. The design of the equipment is presented in the form of an extruder for melting the crushed mass, a strand head for filtering the polymer solution, a bath for cooling the finished product, a device for cutting granules, a hopper for collecting granular particles.

Equipment for polymer processing

For secondary operations, polymer processing provides for equipped directional mechanisms - crushing and grinding production lines. With their help, a preliminary preparatory process of waste polymer products for extrusion and sintering operations takes place. There are three types of different capacity crushing lines.

Depending on the technical equipment of the model used, the grinding devices can carry out the functions of screening, for separating small-sized elements, automatically washing and drying polymeric materials. They are also equipped with conveyor movable belts, metal detectors, anti-noise protection, which greatly simplifies the process of processing the secondary polymer mass.

Recycling of polymers is also an environmentally friendly activity that requires the cost of special equipment. The greatest economic effect, as a rule, is achieved by processing enterprises equipped with modern, high-performance plants. High-quality operation of the equipment is a guarantee of an excellent result, obtaining a quality product in the form of feedstock for further use in the production of polymer products.