Starting a business producing plastic products

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Types of plastics

Currently, the industry produces and uses many types of plastics.

Based on their composition, plastics are divided into:

– sheet thermoplastic masses – plexiglass, vinyl plastics, consisting of resins, plasticizer and stabilizer; – laminated plastics reinforced with one or more layers of paper, fiberglass, etc.;

– fiberglass – plastics reinforced with glass fiber, asbestos fiber, cotton fiber, etc.;

– injection molding masses – plastics that do not contain other components other than polymer compounds;

– press powders – plastics with powder additives.

Based on the type of polymer binder, plastics are divided into:

– phenol plastics, which are made from phenol-formaldehyde resins;

– aminoplasts made from melamine-formaldehyde and urea-formaldehyde resins;

– epoxy plastics using epoxy resins as a binder.

Based on their internal structure and properties, plastics are divided into two large groups:

– thermoplastics that melt when heated, but after cooling retain their original structure;

– thermosets with an initial structure of a linear type, which acquire a network structure during curing, but when reheated, completely lose their properties.

Thermoplastics can be used repeatedly; to do this, they just need to be crushed and melted. In terms of working properties, thermosets are, as a rule, somewhat better than thermoplastics, but when subjected to strong heating, their molecular structure is destroyed and is not subsequently restored.

Production of products from thermosets

For the manufacture of products from thermosets, as a rule, pressing is used, as well as winding, drawing, rolling and (comparatively less often) some casting methods.

Press powders, fiberglass, fiberglass are processed into products using the pressing method, which consists of plastic deformation of the material under the simultaneous influence of heat and pressure, followed by fixing the shape of the product.

During pressing, the material turns into a melt, which is compacted, fills the mold cavity of the mold and hardens. During the compaction process, the particles come together to such a distance that intermolecular interaction forces arise between them, resulting in the formation of a compact body, which is then subjected to volumetric compression.

The main parameters of the pressing process are pressing temperature, pressure and holding time of parts under pressure in the mold.

For example, for thermosets based on phenol-formaldehyde resin (press powders, fiberglass, glass fiber and others), the pressing temperature is 140...160 °C, the pressing pressure is 25...55 MPa, the holding time during pressing is 1...2.5 minutes per 1 mm of thickness details. The pressing pressure and holding time per 1 mm of thickness for specific products are established experimentally, and the pressing temperature can be determined analytically. At the same time, high pressing pressure limits the possible dimensions of the product.

It should be noted that the need to heat the material and hold it under pressure leads to an increase in the complexity of manufacturing parts. The average labor intensity of manufacturing one part using the pressing method is 20 minutes. To reduce labor intensity, tabletting the material and preheating it in thermostats with high-frequency currents or on press plates is used. This allows you to reduce the holding time under pressure by 2...3 times and reduce the pressure by 50%, as well as reduce the wear of molds and improve the properties of the product.

There are direct (compression), injection and extrusion.

Direct pressing is carried out in open, closed and semi-closed molds (Fig. 11). Open molds. consist of a matrix 1, a punch 2 and an ejector 4 (Fig. 11, a). These molds are easy to manufacture, light in weight, low in cost, and are used to produce simple-shaped products from thermosets, mold rubber products, and some parts from laminated plastics. Products molded in open molds have low dimensional accuracy in height, which depends on the thickness of the burr formed in the parting plane. Such molds require the use of pre-compacted material (for example, tableted), since the volume of the sampled material is often greater than the volume of the open cavity of the matrix. The exception is rubber compounds, the density of which is close to the density of the product.

Closed-type molds (Fig. 11, b) have a loading chamber and the flow of material from the molding cavity into them is practically excluded. These molds require precise alignment of the punch and die. They are expensive, wear out quickly, and are used to make deep, thin-walled products from difficult-to-form fibrous or laminated materials.

Rice. 11. Schemes of direct compression molds : a - open mold; b - closed; c - half-closed; 1 - matrix; 2 - punch; 3 - product; 4 - ejector; 5 - excess material

Semi-closed type molds (Fig. 11, c) have a larger loading chamber area than the area of ​​the horizontal projection of the molded product, which prevents material from flowing out of an open mold. In addition, between the punch and the matrix there is a guaranteed gap for excess material to flow out, the value of which is significantly less than when using open-type molds. These molds are the most common.

Injection molding is used to produce parts of complex configurations with metal reinforcement and low wall thickness. During injection molding (Fig. 12), the material is plasticized in the loading chamber and enters the forming part of the mold through the gating channel. The material in a plastic state does not shift the metal reinforcement and easily penetrates into the narrow cavities of the mold. The high cost of molds and increased material consumption are the disadvantages of such pressing. To increase the productivity of the method of pressing powdered and fibrous plastics, multi-cavity molds, rotary automatic lines and other specialized automatic installations are used.

Rice. 12. Diagram of an injection mold : 1 - matrix; 2 - ejector; 3 - product; 4 - punch; 5 - loading chamber; 6 — loading chamber punch

For the manufacture of profile products from press powders and asbestos fiber, extrusion is used, which consists of squeezing the material through a mold with open inlet and outlet holes or through a special head. Extrusion occupies an intermediate position between pressing and extrusion. In this case, compaction of the material is achieved due to the difference in the areas of the punch and the outlet hole of the matrix. For example, for thermoset plastics, the punch area is 3.5...5 times larger than the area of ​​the die outlet.

Extrusion is carried out on horizontal presses, the pistons of which slowly make a working stroke and quickly return to their original state. This method is also used in the processing of fluoroplastic and for the production of massive rods and thick-walled pipes from rigid polyvinyl chloride.

Sheet materials - textolite, asbestos textile, fiberglass, getinaks, wood-laminated plastics are produced by pressing on multi-deck presses. Fillers in the form of fabric (cotton, asbestos, glass), paper, wood veneer are impregnated with a binder (phenol-formaldehyde, epoxy and other resins) and dried. Filler sheets are placed between polished metal sheets. The resulting bags are placed between the press plates, after applying lubricant between the metal sheets. Under the influence of temperature and pressure, the binder melts and then hardens, forming a monolithic material from individual sheets. After holding under pressure, the bags are cooled to a temperature of 30...40 °C, removed from the press and the burr is cut off.

To process fiberglass into products, the following methods are used: contact; molding with rubber boot; molding with an elastic punch or matrix; press chamber; compression pressing, etc.

The contact method uses fiberglass and polyester or epoxy resin, which is capable of curing at room temperature without pressure due to the introduction of special substances - polyethylene polyamine (for epoxy resin), as well as cobalt naphthenate and cumene hydroperoxide (for polyester resin). After the introduction of hardeners, the viability of the binder, i.e., the time before the formation of a cross-linked structure of macromolecules, is about 4 hours. During this time, the entire portion of the prepared resin must be processed. To implement the contact method, a model is required that replicates the configuration and dimensions of the product. In order to prevent the adhesion of fiberglass to the model, it is covered with a separating layer, which is created using technical petroleum jelly, film, and polyvinyl alcohol. Fiberglass impregnated with resin is laid on the model and rolled with a roller to eliminate voids and irregularities. The number of layers of fiberglass is determined by the required strength of the products. When using one layer of TZhS-0.7 glass fabric, a product thickness of about 1 mm is achieved. To obtain a marketable product, it is recommended to use fiberglass with a finer weave. The curing time is approximately 48 hours. After the product has cured, it is removed from the mold.

The contact method is simple and does not require highly skilled labor, but is labor-intensive. In addition, due to incomplete curing of the binder and low pressure, in some cases the products have insufficient strength.

This method is used in small-scale production for the manufacture of large-sized products of complex configuration (sports car bodies, passenger car parts, fan blades, small vessels, dinghies, boats, boats).

When molding products with a rubber cover, rubber punch or matrix, the labor intensity of manufacturing products is reduced and their quality increases (compared to the contact method).

Molding with a rubber cover consists in the fact that a model with impregnated resin and dried fiberglass laid on it is covered with a thin metal shell and a rubber cover, which is hermetically pressed to the model. Air is pumped out from the cavity between the cover and the fiberglass package. Due to the difference between atmospheric pressure and vacuum, molding is carried out. The molding pressure is 0.05...0.09 MPa. In this case, the product is heated by electric heaters installed in the walls of the mold or in a heating cabinet. An autoclave is used to increase the molding pressure to 0.3...2.5 MPa.

When pressing with an elastic punch or die, the pressure is distributed more evenly than with a metal punch. In this case, a package of prepared fiberglass is placed in a matrix or on a punch, heated and pressed under pressure.

Let's look at the press-chamber method for processing fiberglass using the example of manufacturing a large axial fan blade. The mold for such a blade consists of two halves, which are installed on a press that provides the necessary pressure and temperature. A package of fiberglass fabric, pre-impregnated with resin and dried for ease of work, is placed in the lower part of the mold. Granular foam is poured onto the glass unit, another glass fiber pack is placed on top of it and the upper half of the mold is lowered. The cutting edges present in the mold cut the excess fiberglass around the perimeter of the product. Under the influence of heat, the foam foams, its volume increases several times and excess pressure develops, which forms the shell of the blade. The product is obtained with great precision, with good surface finish and with an internal foam core.

The winding diagram for fiberglass products is shown in Figure 3.13. Winding is distinguished between “wet” and “dry”.

In “wet” winding, the glass rope, unwinding from reel 1, is impregnated with a binder in bath 2 and wound onto mandrel 4 (Fig. 13). With “dry” winding, the glass filler is impregnated with resin under pressure after winding.

Rice. 13. Scheme of winding fiberglass products : 1 - reels with glass rope; 2 - bath with a binder; 3 - crimping rollers; 4 - mandrel

There are various winding schemes for glass filler. The most common are spiral winding and longitudinal-transverse.

Spiral winding is carried out by rotating the mandrel and reciprocating movement of the carriage. When winding longitudinally and transversely, the glass strand, using special devices, is placed on a mandrel along the generatrix of the cylinder and along the ring. Longitudinal-transverse winding ensures maximum strength of the product. This is how pipes, tanks, tanks, nozzles and engine housings for rockets, etc. are made.

The broaching method is used to produce profile products (tubes, rods, angles, etc.). The glass rope or glass threads are unwound from the reels, impregnated with a binder in a bath, collected into a bundle and pulled through the forming head. Here the product is shaped and partially cured. For more complete curing, the product is placed in a heat chamber.

Flat and corrugated sheets of fiberglass are produced by the rolling method. Fiberglass mat or fiberglass fabric is impregnated with resin in a bath, then excess resin is removed with squeezing rollers. The impregnated sheets are covered with cellophane, pressed and cured by passing them through heated rollers.

For the manufacture of some fiberglass products, compression molding is used using open molds.

Comparatively less often, injection molding is used for processing thermosets, since in the event of the slightest violation of the technological regime, they can harden in the cylinder, causing a long shutdown of the machine.

Centrifugal and free casting methods are sometimes used to make products from cold-cured epoxy and polyester resins with fillers.

Plastic manufacturing technology

All technological activities are performed by vacuum equipment. The operator controls the process and controls the operation of the unit.

The following is used as a raw material base:

• polycarbonate;
• polyvinyl chloride;
• polyethylene;
• thermoplastic.

Which specific type of material to choose depends on the product and its area of ​​use. All of the listed raw materials meet quality requirements, and they can also be painted in the desired color.

The technological process consists of three stages:

• a matrix is ​​created - an exact copy of the product. The mold is made from materials that are resistant to high temperatures. Most often - from aluminum, fiberglass, thermal types of resins;
• The plastic is given the required shape - the polymer sheet is fixed. Then heated until flexible. The process takes place in a special unit. The matrix is ​​installed inside the equipment in advance. When the plastic begins to stretch, the sheet is automatically fed into the matrix. The flexible polymer fits tightly to the shape. Next, the vacuum pump is connected to work. The device removes air fragments formed at the junction of the workpiece with the plastic. After the polymer fits the matrix as tightly as possible, the automation is activated. The product is cooling. The frame is removed from the mold;
• The final stage is finalization of the product. Fragments of the polymer sheet are removed, the necessary holes are made, and if necessary, fasteners and clamps are inserted.

The finished product is placed on a conveyor and sent for painting. Then - for packaging and further storage in a warehouse.

Main types of waste accepted and prices per 1 kg

By donating plastic waste, you can not only feel involved in preserving the environment, but also receive a monetary reward.

You don’t have to worry about whether the raw materials will be recycled: professionals will recycle them and create new products from them that will hit store shelves again.

Plastic can decompose in the atmosphere within several hundred years. Contributing to the preservation of nature is not difficult; first you need to familiarize yourself with the average cost of receiving material in Moscow.

The table below shows the price per 1 kg at which you can sell various types of plastic, including the popular ABS:

A distinctive feature of some plastic collection points in Moscow is the possibility of removing raw materials from the address. In this case, the cost of admission will be slightly lower. How much exactly, you need to check with the manager.

Of course, the volume of waste must be such that the removal of the company's vehicle is justified.

Addresses of existing collection points

This convenient and quick-to-recycle material has become a real salvation for industry, but its thoughtless disposal threatens nature with pollution. To prevent this from happening, it is recommended to hand over plastic to collection points.

There are several places in Moscow where you can donate plastic: the selection will tell you about addresses, prices, conditions and contact information.

Waste is accepted both from the population and from commercial organizations.

Most companies recommend carefully sorting the plastic by type, color and density before handing it over. This way, the process of accepting recyclable materials will be faster, and its price will be higher.

Some companies work from only 1 ton of raw materials - this is due to large volumes of processing.

Choice of plastics

The main selection conditions are technological and operational properties. To help the technologist, comparative tables have been created containing grades of materials with a description of technical characteristics, while radio engineering and electrical properties, dielectric constant, mechanical and strength indicators are indicated. Wear and friction coefficients, Poisson coefficients, thermal expansion indicators and other characteristics are indicated.

To classify plastics, the following characteristics are used:

• type of filler used;
• performance;
• intended for use in various fields;
• the meaning of some important parameters and performance characteristics.

Raw materials, materials for injection molding of plastics

The raw materials for plastic injection are thermosetting powders, as well as granules of thermoplastics and thermoplastic elastomers. All materials have different mechanical and physical characteristics.

The advantage of thermoplastic materials is that they can be recycled after the molding process. Thermosetting materials in the process of molding a product are subject to chemical processes that lead to the transformation of raw materials into an infusible and insoluble material.

Technologies for the production of plastic products

Plastic production is carried out in the following ways:

• Casting. This is a technological process during which raw materials for plastics are converted into a liquid state. After this, it is poured into special molds. Used to create stationery, dishes and any household goods.
• Blowing – heated material in a liquid state is fed into an open mold, which is immediately closed. Next, air enters the mold to inflate the mold along the walls.
• Vacuum forming. The process involves exposing sheet materials to air pressure.
• Extrusion is the most common method. The plastic is softened and pressed through the hole of the forming tool.

Regardless of the technology for the production of plastic products, raw materials must be of the highest quality. Good raw materials are the key to obtaining a quality item that will last for many years.

The Expocentre Fairgrounds hosts the annual Plastics Industry exhibition, which presents various types of plastics, control and measuring equipment, as well as the latest technologies for processing and producing plastics.

Chemical industry raw materialsPlastics production technologyChemical safety

What is plastic injection molding

Large-scale and mass production of plastic parts involves a complex technological process of injecting molten plastic under high pressure into a prepared injection mold made of metal. The liquid mass evenly fills the volume and crystallizes, acquiring the required shape. Thanks to injection molding technology, it is possible to obtain high-quality products. To implement the method, complex, expensive equipment is used that provides high productivity. Almost half of the polymer parts are produced using this method. Thermoplastic granules, as well as thermosetting powders, are used as raw materials for the production process, giving the finished products the required physical and performance qualities. Thermoplastic components retain their parameters during recycling, while thermoset components undergo irreversible chemical reactions and form an infusible material.

The prepared polymer components are loaded into the hopper of the injection molding machine, in which they are melted and homogenized. Next, the mass is injected at speed, thanks to the pressure created, through special channels into the prepared form. The cavity quickly fills. After solidification, a casting is formed. The quality of polymer products depends on the injection speed. Worm-type plasticizers are the most popular. They are characterized by high productivity and better homogenization of the molten mass. Less popular piston type equipment. It provides the supply of molten polymer at high speed into the injection mold and provides the opportunity to obtain a marble effect in the case of preparing a mixture of multi-colored plastics. In production, the use of a separate method is allowed. It involves the preparation of the molten mass in a preplasticizer with a worm mechanism, and the dosing and injection of the viscous mass into the mold is carried out using piston-type equipment.

Methods for additional mechanical finishing of finished products

This procedure is done for:

• clarifying the shape of finished parts after pressure or casting;
• during the production process of sheet plastic products;
• removing excess layers (burr, sprues, burrs, films), clearing holes in small production conditions;
• increasing savings when producing parts with complex configurations;
• manufacturing a small batch of products or in small workshops.

Mechanical processing is specific due to its viscosity and low thermal conductivity; it is these features that form the tools and machine equipment for plastic processing. The following machining methods are distinguished:

• processing of plastic products by cutting;
• separation stamping.

The first method is used for finishing and removing layers on parts after the hot pressing method and as an independent method for turning products from ornamental plastics. The cutting method consists of separate operations: turning, cutting, drilling, milling, grinding, polishing and thread forming.

Separating direction stamping is used when sheet plastic is used as blanks. Operations performed: stripping, cutting, trimming, punching, cutting or cutting.

Turning is done with the tool deepening to a layer of 0.6-3 mm, distinguishing between finishing and roughing. Drilling is done at different speeds, which depends on the brand of plastic. Milling is used to process to a depth of 1−8 mm (thermosets) and 1−9 mm (thermoplastics); roughing and finishing passes are also distinguished.

Thread cutting is sometimes difficult due to the processing of laminated, fibrous plastics, which can cause thread breaks, chips, or cracks. Grinding is done with carborundum wheels of medium hardness; sometimes sanding paper is used instead of wheels.

The parts are polished to produce a product with a high-quality surface when leaving the workshop. For the procedure, take soft wheels, which are made in the form of a package of muslin discs of various diameters; felt wheels work well for grinding. One part of the grinding disk has abrasive applied to it, the second is free from the sanding layer and is used for wiping.

Examples of defects and solutions

High-quality plastic injection molding that meets standard requirements is ensured by using a technically sound machine, strictly following technological steps and using high-quality raw materials. The table lists the types of defects and actions to prevent them.

Injection molding technology, implemented on modern equipment in compliance with process requirements and the use of high-quality raw materials, allows us to produce large quantities of high-quality products that are in demand in various industries and domestic conditions. By choosing the optimal plasticization method, it is possible to establish cost-effective production of parts of any complexity.

Technology for the production of plastic products

All work to produce plastic products is performed by a vacuum unit, while the operator performs simple actions and controls the process.

Various thermoplastic sheets are used as working material: ABS plastic, polycarbonate, polyethylene, polyvinyl chloride, polycarbonate.

The choice of a particular polymer depends on the purpose of the product being manufactured. All these are high-quality materials that can later be painted.

The manufacturing process is divided into 3 stages:

1. Creating a matrix form. It is a model with the exact shape and dimensions of the future product, which will be covered by a polymer heated to a state of plasticity and flexibility. Matrices are made from heat-resistant materials such as fiberglass, various resins, and aluminum. As a rule, composite materials are used for small-scale production, and matrices made of aluminum and its alloys are used for large volumes;
2. Form formation. At this stage, the rigidly fixed thermoplastic sheet is heated to a temperature where it is capable of stretching. This happens in a special machine in which the matrix is ​​already installed. When the thermoplastic is ready, the automation is activated, and the sheet is lowered onto the matrix, tightening it. In this case, a vacuum pump operates continuously, removing air between the matrix and the sheet. Then the sheet is forcibly cooled and the finished form is removed from the apparatus;
3. Stage of finalizing the form. Involves the removal of excess sheet residues not included in the product. All necessary holes are also cut and drilled. In some cases, additional reinforcement is required, as is the case with an acrylic bathtub.

Advantages of this technology

For the production of large quantities of polymer products, plastic injection molding technology is characterized by the advantages of high casting accuracy. By injecting the molten mass at an increased speed, the mold is uniformly filled, including microscopic holes. The method is characterized by many advantages due to which it is popular:

• Possibility of producing products of any geometric shape and degree of complexity. Thin-walled parts are manufactured. The complexity of the design depends on the mold, which is highly detailed and takes into account all the bends and holes of the future product.
• There is no need for subsequent machining of parts. Some products that are complex in design may require minimal processing.
• Mass production of an unlimited number of plastic parts. The service life of metal molds is tens of years, so they are used for the manufacture of a huge number of polymer products.
• Quick payback when organizing the production of large batches of plastic products. At the same time, the cost of one product decreases without deterioration in quality as the number of copies produced increases. This dependence is explained by a one-time investment of funds at the preparatory stage for the release of a certain type of product.

Technology involving pressure casting has significant costs at the preparation stage, so its use is unprofitable for the manufacture of single products or small batches.

Do I need permission to open?

Production from plastic is harmful, so the organization of the work cycle and premises will require compliance with sanitary, environmental and fire standards. Products must also have certificates and sanitary epidemiological conclusions, especially if we are talking about dishes or toys. It is recommended for production to obtain certification in accordance with GOST R ISO 9001 “Quality management systems. Requirements". Accordingly, the raw materials must also be safe and acceptable for the manufacture of certain products.

Professional business plans on the topic:

• Business plan for the production of disposable plastic tableware (36 sheets) - DOWNLOAD
• Business plan for the production of artificial stone (44 sheets) - DOWNLOAD

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Equipment for the production of plastic products

Standard set of equipment for opening a workshop for the production of plastic goods:

• melting unit;
• device for loading and feeding polymer sheets;
• pressing molds;
• refrigeration equipment;
• bending apparatus;
• stripping unit;
• gluing machine;
• line for painting and drawing;
• line for packaging finished products.

Additionally, you can purchase a 3D printer. The device has a high printing speed and allows you to realize almost any idea. It's easy to work with. The only drawback of the printer is low performance. For large-scale production the thing is useless, but for individual orders it’s just right.

You can choose between domestic or foreign equipment. Start from your financial capabilities. Machines from Europe will last much longer, but will also cost 2-3 times more. By the way, among Russian manufacturers you can also find high-quality lines for processing plastic. But it is better to refuse Chinese automatic lines - they often break down and are expensive to repair.

Manufacturing of plastic products

There are several ways to obtain plastic parts

Plastic injection molding

Used for the production of thermoplastics and thermoplastics. With this method, the material in granular form goes into the cylinder of the machine, where it is heated and mixed by a rotating screw. If a piston machine rather than a screw is used, then plasticization occurs by heating. Thermoplastics are heated to 200−350˚С, thermosets require 85−120˚С. The finished material enters the mold for casting, where it is cooled (thermoplastics up to 25−125˚С, thermosets - 155−195˚С). In the mold, the former raw materials are kept for compaction under pressure, which affects the shrinkage threshold, reducing it.

Intrusion

Allows the same unit to produce parts of a significantly larger size and volume. In the previous process, the casting is plasticized by a rotating worm and fed into the mold by its translational movement. Intrusion involves the use of a nozzle with an existing wide channel to flow the casting into the mold before the translational movement of the worm begins. The total duration of the cyclic process does not increase, but the method shows high productivity.

Press casting

In this case, the loading chamber is located separately from the formation cavity. The pressed material is placed in a loading chamber, where plasticization occurs under the action of heat and compression. The material then flows into the working compartment of the mold, where it hardens. The pressed casting method is used in the production of parts with thick walls, reinforcement, and complex shapes. The disadvantage of this method is a slight waste of material, since some of it remains in the loading compartment.

Fill

The process is used to produce parts from compounds or in the case of insulation and sealing of radio and electronics spare parts with compounds. Compounds are compositions of polymers, plasticizers, hardeners, fillers and other additives. They are waxy solid compounds that are heated to a liquid state before use.

Hardening occurs at a temperature of 25-185˚C, the process takes about 2-17 hours. Sometimes tableted material is poured into the solution container, then the mold is heated and the raw material is melted, to speed up the procedure the pressure method is used.

Winding method

They are used for the manufacture of plastic bodies of rotation, with the starting raw materials being liquid-flowing and glass polymers. Caps, tubular cavities, and cylindrical shells are made. The process takes place on winding machines using mandrels; polymer-treated threads are wound onto them. Winding is carried out dry or wet.

In the first case, a pre-impregnated reinforcing thread is used, and in the second case, impregnation occurs before using the thread. The dry method is recognized as more productive and of higher quality; as a result, a variety of impregnations and binders are used, but the wet method makes it possible to produce parts of complex shapes and shapes.

Introduction to Polymers

Preface

Plastics are materials based on organic natural, synthetic or organic polymers, from which, after heating and applying pressure, they can be molded into products of complex configurations. Polymers are high-molecular compounds consisting of long molecules with a large number of identical groups of atoms connected by chemical bonds. In addition to polymer, plastic may contain some additives.

Plastics processing is a set of technological processes that ensure the production of products - parts with a given configuration, accuracy and performance properties.

High quality of the product will be achieved if the selected material and technological process meet the specified operational requirements of the product: electrical, mechanical strength, chemical resistance, density, transparency, etc.

When processing plastics under conditions of mass production, materials science, technological, scientific, organizational and other problems are solved to ensure high quality products.

Materials science tasks consist in the correct selection of the type and grade of polymer, in such a way as to ensure the possibility of molding a product with a given configuration and performance properties.

Technological tasks include the whole range of issues of polymer processing technology that ensures product quality:

• preparation of polymers for processing,
• development and determination of technological process parameters,
• development of equipment,
• selection of equipment.

The main stages of work on the use of plastics in products are as follows:

• Analysis of product operating conditions, development of requirements for operational properties.
• Selecting the type of plastic according to the specified requirements and performance properties of the product.
• Choosing a method for processing plastic into a product and equipment.
• Selection of a basic brand of plastic and, based on it, a brand with improved technological properties.
• Design, manufacturing, testing and debugging of technological equipment, etc.

Structure of polymers.

Polymers consist of repeating groups of atoms - units of the original substance - monomer, forming molecules thousands of times longer than the length of non-polymer compounds; such molecules are called macromolecules. The more units there are in a polymer macromolecule (the higher the degree of polymerization), the stronger the material and the more resistant to heat and solvents. Due to the impossibility of effective processing of low-melting and sparingly soluble polymers, in some cases, semi-finished products are first obtained - polymers with a relatively low molecular weight - oligomers, which are easily brought to a high molecular level with additional heat treatment simultaneously with the manufacture of the product.

Depending on the composition, groups of polymer compounds are distinguished: homopolymers - polymers consisting of identical monomer units; copolymers – polymers consisting of different starting monomer units; organoelement - compounds with silicon atoms (organosilicon compounds), aluminum boron, etc. introduced into the main chain or side chains. These compounds have increased heat resistance. The shape of the molecules can be:

• linear, unbranched, allowing dense packing;
• branched, more difficult to pack and giving a loose structure;
• sewn - ladder;
• mesh;
• parquet;
• stitched three-dimensional volumetric;
• with a dense network of cross-links;

In organic polymeric materials, the macrostructure is formed either by flexible macromolecules rolled into balls (globules), or by packs-lamellas of more rigid macromolecules, parallelly arranged in several rows, since in this case they have a thermodynamically more favorable shape, in which a significant part of the lateral surface is adjacent to each other to friend. Domains are formed at the folding sites, and the domains create fibrils connected by passage regions. Several domains, connecting along folding planes, form primary structural elements - crystals, from which lamellar structures - lamellas - appear when the melt is cooled. During the process of folding the lamellas, the ends of the molecules can be in different planes; Sometimes these ends of the molecules partially return to the original plane - in this case they create loops.

Properties of polymers.

Polymers in the solid state can be amorphous or crystalline.

When an amorphous polymer is heated, three physical states are observed: glassy, ​​highly elastic, and viscous. These states are established based on the thermomechanical state curve. An amorphous polymer is below the glass transition temperature (Tg) in a solid state of aggregation. At temperatures above Tg the polymer is in a highly elastic state; In this case, molecular mobility becomes so great that the structure in short-range order has time to rearrange itself following a change in temperature, and macromolecules can bend under the influence of external forces. The total deformation in this case consists of elastic and delayed highly elastic deformation. During elastic deformation, the average intercenter and intermolecular distances and bond angles in the polymer chain change; during highly elastic deformation, the orientation changes and the links of flexible chains move over significant distances.

A crystallizing polymer, depending on the cooling rate of the polymer melt, can exhibit two types of structures: amorphous and crystalline. When crystallizing polymers are slowly cooled, the joint stacking of segments of macromolecules forms the structure of macromolecules. This makes it difficult for them to transition from one conformation to another, which is why there is no flexibility of macromolecules and no highly elastic state. During rapid cooling, the crystalline structures do not have time to fully form, so in the supercooled polymer there is a “frozen” - amorphous structure between them. This amorphous structure, when reheated to a temperature above the melting point (Tm), creates a viscous flow state. The polymer structure is characterized by two states: crystalline (up to the melting point) and viscous flow (above the melting point).

The viscous flow state, characteristic of the amorphous and crystalline state of the polymer, mainly provides the necessary deformations during the flow of the polymer through the sequential movement of segments. The viscosity of the polymer increases with increasing molecular weight of the polymer, and the molding pressure of the products also increases.

In conclusion, we note that with an increase in temperature to a certain value, the process of thermal destruction begins in the polymer material - decomposition of the material.

Properties of polymers that determine quality during processing:

• rheological:
• viscous, determining the process of viscous flow with the development of plastic deformation;
• highly elastic, determining the process of development and accumulation of reversible highly elastic deformation during molding;
• relaxation, which determines the relaxation (decrease) of tangential and normal stresses, highly elastic deformation and oriented macromolecular chains;

Viscosity properties of polymer melts.

The molding of polymer products is carried out in the process of their viscous flow, accompanied by plastic deformation. In this case, a thin layer of material in contact with the stationary wall of the tool, due to adhesion to it, has a zero displacement velocity (immobile), the middle layer has the highest displacement velocity V; in steady flow mode, the relationship between shear stress t and shear rate g is linear (Newton's law for viscous liquids): t=h*g, where h is the viscosity coefficient or viscosity. The nature of the dependence of shear rate on shear stress is represented by a flow curve, in which sections are distinguished: 1 – section of linear dependence, characteristic only for low shear stresses; 2 – section with a nonlinear dependence, which is characterized by a decrease in viscosity with increasing shear stress; 3 – area with high shear stress.

Improving the flow of material is facilitated by: an increase in temperature, an increase in shear stress, an increase in the amount of moisture, a decrease in pressure and a decrease in the molecular weight of the melt.

Many properties of polymer materials in products depend on the structure that is formed by the processing process. Depending on the polymer and processing conditions, an amorphous or crystalline structure appears in products.

The structure of a product with an amorphous polymer is characterized by a certain degree of orientation of sections of chain macromolecules and the location of oriented areas along the cross section of the product along the direction of shear (flow) of the material. This leads to anisotropy of properties.

The structure of a product with a crystalline polymer is characterized by a certain degree of crystallinity (from 60 to 95%) and the unevenness of the crystalline regions across the cross section. The properties of such products obtained under different processing conditions, despite the morphological similarity of structure, are different.

Product quality indicators

from polymeric materials depend on the properties, conditions of preparation, processing and physical modification of the material. The appearance of products depends on processing conditions, material purity, and humidity.

Dielectric properties and chemical resistance

depend on the chemical structure and modification of the polymer.

Mechanical properties

- strength, impact resistance, deformation, rigidity, heat resistance - depend on the supramolecular structure, and the coefficient of friction and wear resistance, combustion resistance depend on the chemical structure and modification.

Performance properties

- dimensional accuracy and dimensional stability - depend both on the chemical structure, molecular characteristics, technological properties, and on processing technology and manufacturability of the design.

Thermal stability of polymers

. The main indicator in this case is destruction.

Destruction of polymers

is a change in the structure of macromolecules. Destruction can occur under the influence of heat, oxygen, chemical agents (including water), light, high-energy radiation, mechanical stress, etc., both individually and from a combination of parameters. It is accompanied by a decrease in molecular weight, the release of gaseous and low molecular weight products, a change in color and the appearance of an odor.

Destruction can be accompanied not only by the destruction of macromolecules, but also by their cross-linking (structuring), which causes an increase in the mass and viscosity of the melt. The consequence of this is a violation of all the properties of the material, a decrease in the stability of the properties of products.

When processing polymers, both thermal-oxidative and mechanical destruction can occur, and in hygroscopic materials, hydrolysis can also occur.

Classification of plastics

The characteristics of the classification of plastics are: purpose, type of filler, performance properties and other characteristics. Classification of plastics according to operational purpose:

• by application;
• based on a set of parameters of operational properties;

According to the use of plastics, they are distinguished (rather roughly):

• plastics for the production of food packaging;
• plastics for work in contact with aggressive environments;
• plastics for operation under short-term or long-term mechanical loads;
• plastics for work at low temperatures (down to minus 40-60 C);
• antifriction plastics;
• plastics for electrical and radio engineering purposes;
• plastics for producing transparent products;
• plastics for heat and sound insulation purposes - gas-filled material;

Based on the totality of parameters of operational properties, plastics are divided into two large groups:

• general technical purposes,
• engineering and technical purposes.

Plastics for general technical purposes have lower performance parameters than plastics for engineering purposes. Plastics for engineering purposes retain high mechanical properties not only at normal and elevated temperatures, but can also operate under short-term loads at elevated temperatures. This is not provided by plastics for general technical purposes; they operate in an unloaded or lightly loaded state at normal and medium temperatures (up to 55 C). Plastics for engineering purposes are divided into groups that provide certain properties in a certain range; There are five groups of plastics based on this classification criterion.

According to the value of individual parameters of operational properties

compose a series of plastics for various parameters of performance properties. Classification parameters: mechanical properties, wear properties, linear thermal expansion and others. Depending on the applicability of the filler and the degree of its grinding, all materials are divided into four groups:

• granular,
• powder (press powders),
• fibrous,
• layered.

Technological properties

The technological properties of plastics influence the choice of processing method.

The technological properties of plastics include: fluidity, humidity, curing time, dispersion, shrinkage, tabletability, volumetric characteristics.

Flowability characterizes the ability of a material to viscously flow polymer, extruded for 10 minutes through a standard nozzle under the pressure of a certain load at a given temperature. Thus, for injection molding, materials and processing modes are used in which the melt fluidity is in the range of 2-20 g/10 min, for blow molding - 1.5-7 g/10 min, for extrusion of pipes and profiles - 0. 3-1 g/10 min, for film extrusion - 1-4 g/10 min, for laminates - 7–12 g/10 min. The fluidity of the thermoset is equal to the length of the rod in mm, pressed in a heated mold with a channel of decreasing cross-section. This fluidity indicator, although it is a relative value, allows us to preliminarily establish the processing method: with a Raschig fluidity of 90-180 mm, injection molding is used, with a fluidity of 30-150 mm, direct pressing is used.

Shrinkage characterizes the change in dimensions during product molding and heat treatment:

U = (Lf-Li) / Lf * 100%; UD = (L-Lt) / Lf * 100%; where Y is shrinkage after molding and cooling; Ud – additional shrinkage after heat treatment; Lф, Lи – size of the mold and size of the product after cooling; L, Lt – size of the product before heat treatment and after cooling.

The shrinkage of thermoset products depends on the method of molding the product and the type of cross-linking reaction: polymerization or polycondensation. Moreover, the latter is accompanied by the release of a by-product - water, which evaporates under the influence of high temperature. The shrinkage process occurs over time; The longer the holding time, the more complete the chemical reaction occurs, and the shrinkage of the product after removal from the mold is less. However, after some holding time, the shrinkage remains constant with its further increase. Effect of temperature on shrinkage: Shrinkage increases in direct proportion to the increase in temperature. Shrinkage after treatment also depends on the humidity of the material and the preheating time: with increasing humidity, shrinkage increases, and with increasing preheating time, it decreases.

Shrinkage of thermoplastic products after molding is associated with a decrease in density when the temperature drops to the operating temperature. The shrinkage of the polymer in different directions relative to the flow direction is different for thermo- and thermoset plastics, i.e. polymers have shrinkage anisotropy. The shrinkage of thermoplastics is greater than that of thermosets.

Moisture and volatile matter content. The moisture content in press materials and polymers increases when stored in open containers due to the hygroscopicity of the material or its condensation on the surface. The content of volatile substances in polymers depends on the content of residual monomer and low-boiling plasticizers, which during processing can turn into a gaseous state.

Optimum moisture content: for thermosets 2.5 - 3.5%, for thermoplastics - hundredths and thousandths of a percent.

Particle size distribution is assessed by particle size and uniformity. This indicator determines the performance when supplying material from the hopper to the heating zones and the uniformity of heating of the material during molding, which prevents swelling and uneven surfaces of the product.

Volumetric characteristics of the material: bulk density, specific volume, compaction coefficient. (Specific volume is a value determined by the ratio of the volume of a material to its mass; bulk density is the reciprocal of specific volume). This indicator determines the size of the loading chamber of the mold, hopper and some dimensions of the equipment, and when processing press powders with a large specific volume, productivity decreases due to the poor thermal conductivity of such powders.

Tabletability is the ability to compress a press material under the influence of external forces and retain the resulting shape after these forces are removed.

Physico-chemical fundamentals of plastic processing

Plastic processing processes are based on physical and physico-chemical processes of structure formation and molding:

• heating, melting, glass transition and cooling;
• change in volume and size when exposed to temperature and pressure;
• deformation, accompanied by the development of plastic (irreversible) and highly elastic deformation and orientation of macromolecular chains;
• relaxation processes;
• formation of a supramolecular structure, crystallization of polymers (crystallizing);
• destruction of polymers.

These processes can occur simultaneously and interconnectedly. Only one process will be predominant at a certain stage.

During the molding process, the polymer is heated to a high temperature, deformed by shear, stretching or compression, and then cooled. Depending on the parameters of these processes, the structure and conformation of macromolecules, as well as the physical, mechanical, optical and other characteristics of polymers can be significantly changed.

When a large number of polymers are cooled, a crystallization process occurs.

Crystallization, depending on the state of the melt, leads to different types of structure. Crystallization from a polymer melt in an equilibrium state without deformation leads to the formation of spherulitic structures. The center of formation of such structures is the nucleus, from which ray-shaped fibrils are formed, consisting of many packed lamellae. Fibrils, growing in the radial direction and in width, form spherical structures - spherulites. Spherulites are formed simultaneously in a large number of crystallization centers. Based on this, spherulites at the points of contact form faces and are polyhedra of arbitrary shape and size. Electron microscopy studies show that the fibril of spherulites is composed of many lamellas stacked on top of each other and twisted around the radius of the spherulite.

Crystallization from a polymer melt occurs when crystallizers - nuclei - are introduced into the polymer material.

If crystallization occurs under high pressure (300...500 MPa) and at high temperature, then a crystalline structure of straightened chains is formed; upon rapid cooling of the same melt, crystallization occurs with the formation of complex chains; macromolecules in this case are in the melt in the form of domains, and rapid cooling does not allow them to transform into a new conformation, i.e. acquire an elongated shape. It has also been established that with increasing pressure the crystallization temperature increases. The practical significance of this property: the possibility of the polymer transitioning directly from the melt without cooling to a quasicrystalline state with increasing pressure; in this case, flow is excluded and relaxation processes are inhibited. As the pressure increases, smaller spherulites are formed and therefore the mechanical strength of the products increases. The size of the crystals also depends on the cooling rate and temperature during the molding process. At a high cooling rate, a fine-crystalline structure is obtained, since there is not enough time for the rearrangement of crystals.

Larger polymer structure can be achieved by increasing the temperature, holding time and slow cooling, or by preheating the melt to a higher temperature before crystallization. The shape of the crystals can be changed. Thus, using crystallization centers and artificial nuclei (1...2% by weight), you can regulate the shape of the crystals. When using a crystallizer substrate, a large number of crystallization centers appear near its surface and a densely packed layer of crystals located perpendicular to the surface is formed. Artificial nuclei are additional centers of crystallization; the shape of the crystal depends on the shape of the crystallization nucleus; spherulite structures grow on small crystals, and ribbon-like structures grow on long needle-shaped crystals. The structure-forming agents (seeds) in this case are aluminum and vanadium oxides, quartz, titanium dioxide, etc. Structure-forming agents usually contribute to the refinement of the spherulitic structure of the polymer.

Unsteady conditions of heat transfer and cooling rates during the molding of polymer products contribute to the production of products with a non-uniform structure (smaller crystals near the surface layers).

If necessary, uniform properties of the product can be ensured by annealing or subsequent heat treatment at a temperature below the melting point. During annealing, the volume of the product decreases and the density increases; Moreover, the higher the temperature and the longer the holding time, the higher the density of the product. Heat treatment is appropriate in cases where increased hardness, elastic modulus, mechanical strength, heat resistance and resistance to cyclic loads are required; at the same time, the relative elongation and impact strength decrease.

The completeness of these processes, in addition to destruction, largely determines the quality of the finished product, and the speed of these processes determines the productivity of the processing method. The quality of the product is significantly affected by the rate of polymer destruction, which is increased by thermal and mechanical effects on the material from the working parts of the tools during formation.

The shape of a thermoplastic product is obtained as a result of the development of plastic or highly elastic deformation in the polymer under the influence of pressure when the polymer is heated. When processing thermosets, product formation is achieved by combining physical formation processes with chemical polymer curing reactions. In this case, the properties of the products determine the speed and completeness of curing. Incomplete use of the polymer's reactivity during curing causes instability of the properties of a thermoset plastic product over time and the occurrence of destructive processes in finished products. The low viscosity of thermosets during formation leads to a decrease in the unevenness of properties, an increase in the rate of stress relaxation and a lesser impact of destruction during processing on the quality of finished products from thermosets.

Depending on the processing method, curing is combined with the molding of the product (during pressing), occurs after the product is formed in the mold cavity (injection molding and thermoset injection molding) or during heat treatment of the molded workpiece (when molding large-sized products, for example, sheets of getinax, fiberglass and etc.). Complete curing of thermosets requires several hours in some cases. To increase product removal from the equipment, final curing can be done outside the molding equipment, since shape stability is acquired long before this process is completed. For the same reason, the product is removed from the mold without cooling.

When processing polymers (especially thermoplastics), macromolecules are oriented in the direction of material flow. Along with the difference in orientation, structural heterogeneity arises in different areas of products that are heterogeneous in cross-section and length, and internal stresses develop.

The presence of temperature differences across the cross-section and length of the part leads to even greater structural heterogeneity and the appearance of additional stresses associated with different rates of cooling, crystallization, relaxation, and varying degrees of hardening.

Heterogeneity in the properties of the material (for the above reasons) is not always acceptable and often leads to defects (due to instability of physical properties, dimensions, warping, cracking). Reducing the heterogeneity of the molecular structure and internal stresses can be achieved by heat treatment of the finished product. However, it is more effective to use methods of directed regulation of structures in processing processes. For these purposes, additives are introduced into the polymer that influence the formation of supramolecular structures and contribute to the production of materials with the desired structure.

Branded assortment of polymers

The branded assortment of polymers was created with the aim of quickly selecting the type and brand of polymer for the manufacture of high-quality products. The brand range includes brands that differ in viscosity and performance properties.

The brand range by viscosity is divided into grades intended for processing by various methods (injection molding, pressing, etc.); with increasing grade number, the molecular weight increases and, as a result, the viscosity increases. These are the brands of the basic range. Viscosity grades are modified to improve technological properties:

• To increase productivity, rapidly crystallizing grades are created;
• for products with complex configurations - brands with lubricants;
• heat-stabilized grades.

Based on the basic assortment of grades based on technological properties, grades with improved properties are created by chemical or physical modification. These brands are developed with such properties that, under recommended conditions, they can produce high-quality products in all respects (accuracy, strength, appearance, etc.). Currently, polymer materials are produced in an assortment and therefore for each product and molding method it is possible to select the appropriate base brand of polymer and, if necessary, a brand with improved technological properties.

In order to produce quality products, basic brands are divided into groups:

• depending on the viscosity of the polymer and the thickness S of the wall of the product;
• depending on the relative length of the product L/S (S-length);
• The entire set of plastic brands contains about 10,000 items.

Choice of plastics

Signs of choice. The main criteria for choosing plastics are operational and technological properties. To speed up the process of selecting a material, special tables are used, each of which shows grades of materials in order of decreasing average value of the presented performance property.

The procedure and algorithm for selecting plastics.

Plastics are selected based on the requirements for the performance properties and geometric parameters of the product. Therefore, first, a type of plastic is selected based on the requirements for its performance properties, and then a basic grade and a grade with improved technological properties, which can be effectively processed using the chosen method. There are two methods for selecting the type of plastic:

• analogy method – qualitative;
• quantitative method.

The analogy method is used when it is impossible to accurately specify the parameters of the operational properties of plastic; in this case, the characteristic parameters of operational properties, purpose, advantages, limitations, recommendations for use and processing methods are used to select; in this case, recommendations for the use of plastics in other types of products operating under similar conditions can also be used for selection.

The procedure for selecting plastics using a quantitative method based on a set of specified values ​​of performance properties comes down to the following:

• identification of the operating conditions of the product and the corresponding values ​​of the parameters of the operational properties of plastics under the basic operating conditions of the product;
• selection of plastic with the required performance parameters;
• checking the selected plastic according to other parameters not included in the main ones.

Injection molding is a method of molding products from polymer materials, which consists of heating the material to a viscous-flowing state and pressing it into a closed injection mold, where the material takes on the configuration of the internal cavity of the mold and hardens. This method produces products weighing from several grams to several kilograms with a wall thickness of 1-20 mm (usually 3-6 mm). To carry out injection molding, plunger or screw injection machines are used (Fig. 1), on which injection molds of various designs are installed (Fig. 2).

Rice. 1. Diagram of an injection molding machine with screw (a) and plunger (b) plasticization of the melt:

1 — hydraulic cylinder of the closing mechanism; 2 — piston of the hydraulic cylinder of the closing mechanism; 3 - movable plate; 4 - half-forms; 5 - fixed plate; 6 — plasticizing cylinder, 7 — screw; 8 — loading window of the plasticizing cylinder; 9 - bunker; 10 — screw drive; 11 — hydraulic cylinder housing of the injection mechanism; 12 — piston of the injection hydraulic cylinder; 13 — auger hydraulic cylinder; 14 - torpedo - melt flow divider; 15 — dispenser; 16 - plunger

Rice. 2. Injection mold:

1 - movable half-mold; 2 - pusher; 3 — ejector plate, 4 — ejectors; 5 — channels of the mold temperature control system; 6 — sprue bushing; 7 - central sprue; 8 — centering sleeve; 9 — centering column; 10 - fixed half-mold; 11 — nozzle of the injection molding machine; 12 — spreading sprue; 13 — inlet sprue; 14 - forming cavity

The main technological parameters of injection molding processes are melt temperature Tr, mold temperature TF, casting pressure RL, pressure in the mold RF, holding time under pressure tvpd, cooling time tcool or curing time in the mold totv for thermosetting materials. Injection molding processes both thermoplastic and thermosetting materials, but the type of material determines the specific physical and chemical processes that accompany the heating and solidification of these types of plastics. The technological flow diagram of the process is shown in Fig. 3. Analysis of the injection molding process can be carried out according to the following components: transfer of the material to a viscoplastic state -> its supply to the dosing zone -> accumulation of the melt -> melt flow in the nozzle-mold system -> melt flow in the channels of the mold and mold cavities -> formation of the structure of the product.

Rice. 3. Technological diagram of injection molding:

1 — car (gondola car, tank); 2 — suspended crane beam; 3 - material warehouse; 4 - vacuum dryer; 5 - injection molding machine; 6 — conveyor; 7 - machining machine; 8 — packing table; 9 - crusher; 10 - extruder; 11 — cooling bath; 12 - granulator

Manufacturing of plastic products - types of products

The scope of use of plastic as a material has virtually no restrictions. This is an additional argument in favor of business.

Potential clients of the production plant:

• plastic goods are:
• agricultural industry;
• medical institutions;
• construction companies;
• automobile enterprises.

The most popular types of products:

1. packages;
2. disposable tableware;
3. bottles and other containers for drinks, household chemicals, hygiene products;
4. buckets, basins, water tanks;
5. containers for food and household items;
6. children's assortment - toys, dishes;
7. spare parts for cars;
8. linoleum;
9. construction fasteners;
10. equipment for playgrounds, leisure and entertainment centers, schools and kindergartens.

We will advise you on any questions!

Plastic parts are widely used in all industries. The scope of human activity is also associated with the use of plastic, from building materials and household appliances to kitchen utensils. The most popular method of manufacturing various products is plastic injection molding technology. Modern equipment makes it possible to automate the production process and obtain products with excellent technical characteristics in a short time with minimal investment. Polymer products are recyclable and therefore are an environmentally friendly material.

Step-by-step plan for opening the production of plastic products

The focus is on small private businesses:

Official opening of the business. Registration of a business, choice of taxation depending on the taxes, you will need to submit declarations and advance reports using applications (it’s easier), naturally, open the necessary types of activities;

Market research. The most important stage, even before drawing up a business plan. In megacities the issue is more complicated due to great competition. Here it makes sense to work on a large scale, focusing on deliveries to other cities. In small towns and rural areas, you can make the most ordinary household items for everyday use, and this will already bring profit;

Availability of production capacity. These are production areas and equipment. The space can be an ordinary garage or a non-residential room in a large house. It's more difficult with equipment. Initial capital is required to purchase it. But there is an option to make a vacuum installation yourself (descriptions are available on the Internet). After working on it a little, you can save money for a more serious unit;

Continuous improvement of the technical process and possible expansion of the range

It is necessary to constantly study advanced technologies in this area and focus on developing standard manufacturing processes for products. This will help you quickly reorient production to market demand conditions and always stay afloat.

Currently, the process of manufacturing products using vacuum forming is a promising investment. Therefore, it is worth trying to build a business in this area.

Plastics components

In any plastic product, polymer is an essential component. However, a very small part of this material consists exclusively of polymers; various impurities are usually added to it - fillers, dyes and stabilizers.

The polymer is a binder; the polymer molecules are connected into a spatial lattice. Polymers can be synthetic or natural. Natural polymers include starch, protein and cellulose, but they are used much less frequently than synthetic materials.

There are two types of polymers depending on the type of processing:

• Thermoplastics are polymers that can soften and harden many times with alternating cooling and heating. Typically, such materials are readily soluble in organic liquids. Thermoplastics include polystyrene and polyethylene.
• Thermosetting. These polymers are susceptible to temperature, but they only harden once. They do not dissolve in organic matter and are more durable. This type includes urea and phenol-formaldehyde polymers.

In construction and the production of household goods, thermosetting raw materials are much more often used, as they have better performance characteristics. There are main types of polymers that are actively used in production:

• Polymerization - polyethylene obtained from high-temperature processing products. The material retains its elasticity well and is resistant to various acids and solvents.
• Polyvinyl chloride is a common polymer in the construction industry. Withstands high temperatures, melts only at a temperature of 200 degrees. From these raw materials, linoleum, any finishing films, pipes, skirting boards, and artificial leather are obtained.
• Polystyrene is a strong but fragile material. Thermal insulation and facing tiles are made from it.
• Phenol-formaldehyde polymers are the first synthetic materials to be used in construction. They are actively used in the production of glue, varnish and paints.
• Urea-formaldehyde polymers are the cheapest type of plastic raw material. They quickly fail and deteriorate when exposed to water, although they are highly durable.
• Polyester polymers are raw materials for the production of varnishes and paints. This group includes epoxy polymers for narrow applications, which are high cost and cannot be used everywhere.
• Organosilicon substances are all silicon-based polymers. The substances have chemical and thermal resistance and combine well with various types of silicates. They are used in the manufacture of paints and protective coatings, as well as in the production of facing products.

Application of plastics

Plastics can perfectly replace the functions of many metal, concrete or wooden products that are more expensive to manufacture. This material is used everywhere in both industry and everyday life.

1. In land, sea and air transport, the use of plastic parts and machine parts significantly reduces their weight and cost.

2. In mechanical engineering, plastic is used to make: technological equipment; plain bearings; gears and worm wheels; brake parts; working containers, etc.

3. In electrical engineering, many types of plastics are used for the production of device housings, insulating materials, etc.

4. In construction, supporting structures made of plastic, finishing and roofing materials, ventilation devices, awnings, panels, doors, windows, working tools, etc. are used.

5. In agriculture, greenhouses are constructed from translucent plastic sheets.

6. In medicine, most devices and devices consist of plastic parts and components. And many human organs most often replace them with plastic analogues.

7. Everyday life is full of plastic products. These are dishes, televisions, computers, mobile phones, shoes, clothes, etc.

Other plastic items

In addition to the listed types of plastic, scrap is also accepted in Moscow - this includes:

• remnants of plastic car bumpers;
• furniture;
• hoses;
• cellular polycarbonate;
• cuttings of plastic window frames.

The price for 1 kg at collection points for this type of plastic will be as follows:

• furniture - from 10 rubles;
• frame trims - from 12 rubles;
• hoses - from 15 rubles;
• polycarbonate - from 15 to 25 rubles;
• car bumpers - from 12 rubles;
• road barriers - from 10 to 12 rubles.

At the time of reception, material can also be sorted at the points.

For example, PET bottles are accepted with corks, rings and labels. Some locations ask you to pre-sort bottles by color into clear and brown.

At some points, pressed PET bottles are accepted for acceptance, and the larger the volume of raw materials delivered, the more money a person will receive.

In addition, if the bottles are pre-sorted by color, the payment fee will also increase. The final price for raw materials is announced by the point employee at the time of complete inspection of the material.

You can get more information about sorting plastic from the article “How to sort plastic for recycling?”

What are plastics made of?

The raw materials for the vast majority of plastics are coal, natural gas and oil. From them, simple (low molecular weight) gaseous substances are isolated through chemical reactions - ethylene, benzene, phenol, acetylene, etc., which are then converted into synthetic polymers during polymerization, polycondensation and polyaddition reactions. The excellent properties of polymers are explained by the presence of high molecular weight bonds with a large number of initial (primary) molecules. Some stages of polymer production are complex and extremely environmentally hazardous processes, so the production of plastics becomes accessible only at a high technological level. At the same time, the final products, i.e. Plastics are generally completely neutral and do not have any negative impact on human health.

Applications of polymer injection molding

Using technology that involves plastic injection molding, it is possible to produce simple and complex plastic parts. There are no restrictions on the dimensions and number of products. This method is used in the automotive industry, electronics, chemical and many other industries. Using the plastic injection method, it is possible to quickly and with the required level of quality produce:

• different packaging, lids and different caps;
• a wide range of children's toys;
• housings and components for electronic equipment;
• components for medical equipment and other products.

How were plastics invented?

The world's first plastic was made in the English city of Birmingham by metallurgist A. Parks. This happened in 1855: while studying the properties of cellulose, the inventor treated it with nitric acid, thanks to which he launched the polymerization process, obtaining nitrocellulose. The inventor named the substance he created by his own name - parkesin. Parks opened his own company to produce parkesin, which soon became known as artificial ivory. However, the quality of the plastic was poor, and the company soon went bankrupt.

Subsequently, the technology was improved, and the production of plastic was continued by J.W. Hite, who called his material celluloid. A variety of products were made from it, from collars that did not need to be washed to billiard balls.

In 1899, polyethylene was invented, and interest in the possibilities of organic chemistry grew exponentially. But until the mid-twentieth century, plastics occupied a rather narrow market niche, and only the creation of PVC production technology made it possible to produce a wide range of household and industrial products from them.