Who made the world's first plastic bottle. Creative project "new life of a plastic bottle"

How nice it is to open a bottle of cold drink on a hot day! No matter what, just to quench your thirst. Someone likes Cola, someone likes beer, someone likes ordinary lemonade. Drinks in glass bottles are so commonplace that few people wonder about the history of the glass bottle.

The first glass bottle is dated 1370 BC. It was found by archaeologists during the excavations of the Egyptian Tel Amarna. This vessel was cylindrical in shape with a narrow neck. Scientists have determined the manufacturing technology of the first glass bottles - this is a method of molding quartz sand with subsequent firing. These bottles were expensive and rare.

The development of bottle technology took place in the 1st century BC. The first bottle made by blowing molten glass was found in Phoenicia. Samples found later showed that there were then standards for making bottles. These standards concerned volume and form. Roman bottles had a clear standard and were branded with an imperial hallmark. Most likely, the empire held a monopoly on the production of bottles.

The glass blowing method for mass production of bottles has been used for a very long time. Phoenicians, Romans, Europeans after the Crusades - this is how the production of bottles spread throughout the world. It took mankind twenty centuries to think of the mass production of these dishes in automatic mode. Now they produce several types of bottles for wines, cognacs, drinks. Exist international standards for medical bottles.
All modern production cheap dishes became possible thanks to the invention of the bottle machine by the American inventor Michael Owens. He came up with an automatic machine that fed molten glass through 6 sleeves. Molten glass was forced into the mold using a vacuum pump. Owens received a patent for his invention in 1903. Five years later, Owens' patent was owned by the German Manufacturers' Union in order to bury the mass production of bottles forever. German manufacturers did not want to lose the fabulous profits from handicraft glass production. Their venture failed.

Many enterprises began to make their own vacuum machines and produce bottles for drinks on a large scale. The need for large quantities appeared with the invention of metal bottle caps, which made it possible to preserve drinks for a long time under high pressure.

With these inventions, the bottle machine and metal caps, the bottle has been firmly established on store shelves and in our refrigerators for a century. Of course, glass containers have lost ground a little with the introduction of food-grade plastic. But we will not see the decline of automatic bottle production for a long time. It is possible that this will be with our descendants.

Many years ago, mankind invented wine. People immediately appreciated this drink and learned how to prepare it for future use. But vessels were needed to store and transport wine. Initially, containers of natural origin were used - animal stomachs, wineskins (leather bags made from whole animal skins). A little later, they began to make wooden, earthenware and metal vessels, in which wine was stored. And, of course, in order for it not to spill, these containers had to be covered with something. Ordinary pieces of wood acted as the first traffic jams. They were customized to the desired size and clogged the neck. Ancient Greek amphoras were also covered with pieces of wood. Over time, people have noticed that tightly corked wine is stored much longer and improves its taste.

Ancient Greek myths tell us that the god of trade and profit, Hermes, had the ability to perfectly clog vessels. Perhaps that is why the ancient Greeks managed to establish a trade in this drink, while receiving a good income.

The first corks were made from soft wood, as it was easier to plan and shape the cork to the desired shape and size. Of course, such plugs did not seal the vessel hermetically. In addition, they quickly absorbed moisture, increasing in size, which caused the neck of the jug to crack. To avoid this, the top of the cork was filled with resin. This protected it from swelling and also ensured tightness.

Over time, the Phoenicians and Romans began to use oak bark to make corks. The famous French monk Pierre Pérignon, after whom the no less famous brand of champagne was later named, repeatedly experimented with various methods of corking wine. A cork in the shape of a cone was considered universal, as it fit almost any size of a vessel with wine. In addition, such a cork was quite easy to remove.

At the beginning of the 17th century, they began to make glass bottles which could be tightly closed with a cork. The cork acquired its modern cylinder shape when the corkscrew was invented. Since that time, when corking wine, corks were driven up to the very neck of the bottle. This method was recognized as the best, and besides, there were no problems with how to remove the cork from the neck of the bottle.

Beginning in the 19th century, cork began to be produced on an industrial scale. The bark of the cork oak has served as the material to this day. The homeland of this plant is considered to be the southwestern part of Europe, however, because of the cork, it began to be grown in many Mediterranean countries.

At first glance, the process of cork production is quite simple, but it is not. In fact, there are many subtleties and nuances. It takes at least fifteen years for an acorn to turn into an oak tree from which the bark could be cut. Add nine more years to this, since the first cut cannot be used, and the next one will grow just in this period of time. It is known that oak is a long-lived plant, living for about 170-200 years. However, during this time, the bark can only be cut from it sixteen times.

While studying the history of the plastic bottle, we learned that the plastic bottle first appeared on the US market in 1970 almost 40 years ago. In Russia, plastic bottles gained popularity after entering the market soft drinks Western corporations Coca-Cola and PepsiCo.

The first plant for the production of lemonade in plastic bottles in the USSR was opened by PepsiCo in 1974 in Novorossiysk. The first plastic bottle weighed 135 grams. Now she weighs 69 grams. In the modern world, no one is surprised by the appearance of a plastic bottle. Such bottles, as a rule, have a larger volume than glass ones, and are safer due to elasticity.

Nowadays, plastic bottles are used not only by manufacturers of carbonated drinks and beer, but also by cosmetic and perfume factories. The production of plastic bottles (eggplants) from this polymer was first created in 1977 for carbonated drinks by specialists from the American Du Pont Company. Now eggplants with a capacity of 0.2 to 5-6 liters all over the world are bottled with vegetable oil, mineral and ordinary drinking water, beer, low-alcohol cocktails, dairy products.

There is an opinion that the future belongs to PET containers: it owes this to its main advantages:

firstly, the small weight of plastic containers (a 5-liter bottle weighs 95 grams),

secondly, the plastic eggplant is strong enough (by accidentally dropping a bottle of liquid, you won’t break it, unlike glass containers; besides, pet containers can withstand a static vertical load of at least 60 kg),

thirdly, pet packaging is environmentally friendly, i.e. chemically inert, does not emit harmful substances, fourthly plastic utensils can be completely recycled, and after processing to get secondary raw materials. And yet, the production of PET containers is much cheaper than the production of glass bottles and aluminum cans.

The starting material for the production of plastic bottles are PET preforms, from which, after preheating, plastic bottles are made by stretching and blowing. PET preforms, in turn, are made by injection molding from granular polymer-polyethylene terephthalate. The color and transparency of the future bottle are laid during the manufacture of the preform from granules.

The production of PET containers in Kazakhstan began to develop actively only in last years. The main consumers of plastic packaging are manufacturers vegetable oil, which pour almost 100% of their products into such containers. But the growth in the production of well-known brown large-capacity plastic bottles (up to 2.25 liters) was provoked by brewers. Producers of mineral water and drinking water have invested their share in the growth of bottle production.

1.3 Environmental problems with plastic bottles

Our parents remember the time when, even in our village, glass bottles were collected and handed over to stores in exchange for some kind of food product, and these bottles were taken away for processing and production of new bottles. And now? And now there are points for receiving glass containers, but for some reason, few people do this. Therefore, glass and plastic bottles litter our streets! And not only!

Accumulations of plastic bottles on the planet are already forming real floating continents in the oceans. Scientists are sounding the alarm: giant deposits of garbage have accumulated in the Pacific Ocean. This is mainly plastic and petroleum products. They are located somewhere between Japan and the west coast of the United States. According to rough estimates, this "plastic island" weighs 100 million tons. And basically it is a kind of mixture of semi-decomposed plastic, which is not visible either from the air or from a satellite.

According to the World Wildlife Fund, these accumulations of garbage pose a great threat to living organisms. According to the Japanese scientist Katsuhiko Saido, when plastic decomposes, it releases toxic substances that can cause serious hormonal disorders in both animals and humans.

The threat from plastic containers to the Earth's ecology is not limited to this. The production of plastic bottles in the US alone takes about 18 million barrels of oil per year. People are already tired of the plastic waste that they themselves create. The creation of plastic packaging solved many problems, but also gave rise to no less of them. The garbage that our fathers left in places of rest has long turned into dust, and even our great-great-grandchildren will see our plastic bottles, because they are “eternal”.

How long is garbage stored?

Very often, walking along the banks of a river, lake or in a forest, people meet garbage with bitterness. They meet, get upset, but leave him lying in the same place, with the thought: “Nothing, it will wash away with rain, rot, in general, go somewhere. It will take away the water." But we are deeply mistaken ... Each type of garbage has its own decomposition period. So a plastic bottle has a decomposition period of 100 years - this is a whole century.

STORY

The raw material for the production of PET bottles is polyethylene terephthalate (PET).
For the first time, polyethylene terephthalate was obtained in 1941 by British Calico Printers (England) in the form of a synthetic fiber. The copyright for the use of the new material was acquired by DuPont and ICI, who in turn licensed the use of PET fiber to many other companies.
Until the mid-60s, PET was used to create textile fibers, after it began to be used to make packaging films, and in the early 70s, the first PET bottle("DuPont" wanted a plastic container that could compete with glass in the manufacture of containers for bottling carbonated and still drinks).
To date, the manufacture of food packaging is the most significant area of ​​application for PET granules. The pioneers in the development of the first industrial blow molding machines were "Sidel" (France) and "Krupp Corpoplast" (Germany).*

* Transformed into "SIG Corpoplast GmbH", part of the "SIG Beverages" group of companies.

PROPERTIES OF PET CONTAINERS

The benefits of PET are numerous. A normal half liter PET bottle weighs about 28g, while a standard bottle of the same volume made of glass can weigh about 350g. PET is completely transparent, a bottle made from this material looks clean, attractive, natural transparency material makes it ideal for dispensing sparkling water. In addition, PET can be dyed, for example, green or brown, in order to appearance products meet the needs of consumers. The use of plastic bottles helps to eliminate such an unpleasant effect as container breakage during transportation, which is characteristic of glass containers, while PET, like glass, is perfectly (and completely) recycled. In general, PET packaging, with its limitless innovative potential and wide design possibilities, is now viewed not as a competitor to glass containers, but as a material capable of opening completely new markets and generating completely new consumer priorities.

Significant disadvantages of PET containers are their relatively low barrier properties. It allows ultraviolet rays and oxygen to enter the bottle, and carbon dioxide to the outside, which degrades the quality and shortens the shelf life of beer. This is due to the fact that the high-molecular structure of polyethylene terephthalate is not an obstacle for gases that have small molecular sizes relative to polymer chains. The maximum shelf life of beer in PET is called different, it largely depends on the region in which bottling is performed.

So, according to German standards, beer in PET becomes unfit for consumption after two weeks, according to ours it can be stored for three to four months. However, all experts agree on one thing: the maximum increase in the degree of gas and light impermeability of a plastic bottle, and, accordingly, the shelf life of beer, is an urgent problem. The companies Sidel, SIG Corpoplast and Sipa are especially actively working on solving this problem.

The main, most promising areas are recognized (in chronological order): multilayer technology , production of bottles from alternative plastics , making into PET special "barrier" additives and spraying "barrier" layers of another material . In addition, work is underway to bottle shape optimization to achieve the best surface to volume ratio.

Multilayer bottle
Multilayer technology today is perhaps the most common and reliable, as it has been tested by time. The bottle produced using this technology resembles layered cake: between the film layers of polyethylene terephthalate there is a layer (or layers) of a special polymer that prevents the penetration of gas and ultraviolet rays (passive barrier) or absorbs oxygen (active barrier). The outer and inner layers of the bottle are usually made from pure PET. Depending on the number of internal "barrier" layers, the total number of film layers ranges from three to five. The most significant disadvantage of multi-layer packaging is a higher (relative to conventional single-layer) price - equipment for the production of multi-layer PET bottles costs, on average, twice as much as usual. Multilayer PET bottles are used for bottling their brands by such well-known companies as "Budweiser", "Carlsberg", "Grolsch", "Holsten", "Miller" and others.

Another disadvantage is that the use of multi-layer technology for the production of PET bottles limits the possibility of its recycling. At the same time, three-layer technology is used in Germany, Switzerland, Sweden, Australia and New Zealand for the recycling of recycled PET: it is placed between film layers of new polyethylene terephthalate. The barrier properties of such a bottle do not improve at all, but from an environmental point of view, such a move can be justified.

passive barrier
The most "popular" to date is technically the most simple three-layer PET bottle, in which a layer of nylon (most often Nylon MXD6) is located between two layers of polyethylene terephthalate. The advantages of nylon are good barrier properties, high transparency, low cost. Ethylene vinyl alcohol - EVON (EVON) and ethylene vinyl acetate - EVA (EVA) have even better barrier properties. But EVA has a noticeable drawback: it loses its protective qualities from moisture. The shelf life of beer in a multi-layer PET bottle with these protective layers is increased by four to six times.

active barrier
The copolyester-oxygen scavenger "Amosorb" can be called today as a purely active barrier. Most companies prefer to work on the creation of combined options for barrier layers that not only absorb oxygen, but also keep carbon dioxide out. Among the most famous materials are "Aegis", "Amazon", "Bind-Ox", "DarEVAL", "Oxbar", "SurShield". According to experts, the cost of a PET bottle with active barriers is almost an order of magnitude higher than a similar single-layer container.

Barrier layer spraying
The deposition of a layer with increased barrier properties is a very expensive process. For its implementation, it is necessary to additionally purchase special equipment, including vacuum machines worth from 1 to 1.5 million Euros.

But so far, these technologies, due to their extreme high cost, have not become widespread. Spraying can be both internal and external. The internal coating is created using the so-called "plasma technology". According to this method, a PET bottle is filled with a special gas mixture, after which it is exposed to a powerful microwave pulse. As a result, the gas mixture for an insignificant period of time passes into the state of plasma, after which it settles in a thin layer on the walls of the bottle. The most famous are the carbon mixtures of the "Actis", "DLC" mixtures, as well as the "Glaskin", "VPP" mixtures. In addition, the technology of spraying quartz glass on the inner surface of the bottle is used (technologies from SIG Corpoplast and HiCoTec). For external spraying, a PET bottle is placed in a special chamber with a gas mixture, which is deposited on the outer surface of the container. For this, sprays "Bairocade", "SprayCoat", "Sealica" are used.

Application of barrier additives
For the most part, the same barrier materials that are used in the manufacture of multilayer containers are used as additives. This is the most inexpensive way to increase the barrier properties of a PET bottle. Most often, "Amosorb" (as an oxygen scavenger), nylon and polyethylene naphthalate (PEN) are added to polyethylene terephthalate. But here a dilemma arises: the more additives are added to PET, the higher the barrier properties of the bottle and the more expensive it is. Besides a large number of additives leads to cloudiness of PET. The golden mean when using PEN as an additive is a value of 8-10%.

Alternative materials
Polyethylene naphthalate remains the main alternative material for the manufacture of plastic beer bottles. PEN has high barrier and heat-resistant properties (an order of magnitude higher than that of PET), which prolongs the shelf life of beer and allows it to be pasteurized. At the same time, the price of this polymer is still rather high (relative to polyethylene terephthalate), which limits its wide application. The exceptions are countries where the government encourages brewers to use reusable plastic containers.

In Europe, about 40% of the total amount of containers used in beer bottling is occupied by a reusable PEN bottle. First of all, it is distinguished from a disposable one by a heavier weight - about 100 grams. Such a bottle can be used up to 40 times. With each bottling, a special mark is applied to the bottle, due to which a record of the "turns" of the container is kept. After applying the last mark, the bottle goes for general disposal. In the European region, the brands "Carlsberg" and "Tuborg" are poured into reusable PEN bottles.

PRODUCTION OF PET BOTTLES

The expansion of the use of PET packaging as an innovative and future-oriented product goes hand in hand with the development and implementation of equipment for the production of plastic bottles and bottling. Equipment equipped with features and capabilities such as fully automated inspection and rejection, setting and changing all operating parameters for each bottle or its contents, real-time touch control and technical support from the equipment manufacturer via the Internet.

One of the main advantages of PET containers is the ease with which a beverage manufacturer can install a PET container production line directly at its enterprise, and this way significantly reduces the cost of containers and, accordingly, is very attractive for beer and beverage producers. From a fully automated line for the production of bottles, the bottles go directly to the bottling line. Thus, no additional costs and space are required for storage and transportation, and the manufacturer gets the opportunity to independently determine the parameters of the container (the standard volume is usually from 0.5 to 3 liters) and develop its design. Since PET bottles are very light and do not break, they do not require crates. It is quite enough to pack them in a plastic film with a cardboard pallet or even without it. This factor leads to further savings on packaging materials, cleaning containers (boxes), transportation, etc. The size of PET bottles is constantly increasing. Bottles designed for water and vegetable oil today often reach a capacity of 10 or even 20 liters.

Preforms
PET bottles are produced by a process known as internal blow molding ( injection stretch blow molding, ISBM). This process has been the subject of numerous adjustments and improvements and is thus now well understood, understood and well controlled.

ISBM is a two step process, including the manufacture of a "matrix", that is, preforms , which looks like a thin glass test tube (phase 1). Then the preform is softened by heating and, with the help of internal air blowing, it is made from it full size bottle (phase 2). The final shape of the bottle neck is given at the preform manufacturing stage. Actually, in the future only the body of the bottle is blown. A feature of all PET bottles is a ring on the neck. It is located on the neck of the preform, located slightly below the thread. It allows the preform to be mechanically gripped and moved to the final blowing point, and also facilitates the transportation of the finished bottle.

Preforms are produced using multi-cell equipment capable of producing up to 144 preforms in one blowing cycle. The production of preforms is, in fact, a very special area, and numerous specific factors influence the quality of the preform and its ability to turn into a full-fledged PET bottle. However, the number of manufacturers offering standard preforms ready to be produced from standard bottles is very large. On the market there are varieties of preforms with different neck sizes. Bottles with a neck size of 28 mm (meaning the outer diameter, including thread - Ed.) are the most popular among beverage manufacturers, however, samples with a large neck size or with a neck designed for crown capping are also produced. The weight of the preform material is determined mainly by the final capacity of the finished bottle that will be made from this preform, as well as the thickness of the bottle walls. For several years now, colored preforms have been produced, mainly brown, green and blue. Dyes and additive manufacturers now offer a very wide range of colors, with dyes specifically designed for PET.

For the manufacture of PET containers, there are two types of equipment, namely single-phase and two-phase. In a single phase process the preform is made from polyethylene terephthalate granules in the same machine in which the finished bottle is subsequently blown out of it. As a matter of fact, in this case, both phases of bottle production are combined in one equipment, so that the preforms often arrive at the final blow while still warm.

In a two phase process the preform is made on one machine and only then is transported for bottle blowing to another, which is responsible for the second stage of the process, or placed in a warehouse, where it is stored until it is needed. This sometimes makes sense, since the preform takes up about 12 times less space than the finished bottle, and besides, it must be taken into account that the same preform can be used to produce different bottles. Since the second stage of the two-phase process is much shorter than the first, it is possible in this embodiment to achieve very high productivity of the equipment that produces the final product, if only the appropriate preforms are in abundance. Usually one machine produces 1200-1400 bottles per hour.
The productivity of the equipment depends on the number of blow cells in a particular machine, as well as on the time of the working cycle, which in turn is determined by the thickness of the walls of the preform and its cooling time.

A beverage manufacturer that decides to opt for a two-phase PET bottle manufacturing process can either produce preforms in-house or buy them externally. The second option gives the manufacturer more flexibility at the initial stage of production, and also relieves him of the need to control the quality of the raw material, to ensure that it is dry enough and, accordingly, whether it is suitable for use. In addition, in the future, he can establish and own production preform, if necessary. Buying preforms also allows you to vary their types, weight, etc. without additional time and money spent on replacing expensive blowing cells. The beverage manufacturer can choose the bottle preform most suitable for their product, whether it is a clear 2L PET bottle for mineral water, a brown dyed preform for a half liter beer bottle or a heavier preform for a reusable soda bottle. Product changeover is facilitated - a factor that, given the high production volumes, is becoming very significant for many beverage manufacturers.

The wide range of preforms available on the market drastically simplifies the task of selecting containers for small beverage companies. They can easily purchase the PET, PEN or composite preforms they require. Also offered are multilayer preforms with an inner layer of nylon or other high-strength material that serves to increase the consumer properties of the bottle. It is even possible to include a layer of recycled polyethylene terephthalate in the preform that does not come into direct contact with the contents of the bottle, which is sometimes done to reduce the cost of raw materials. The final properties of a particular preform are dictated by many and varied factors, reflecting both the production process and the fate of the filled bottle on the market. These factors include not only the size and content of the bottle, but also the method of filling (hot filling, etc.), the type of capping of the neck of the corresponding diameter (which can be much larger than the standard 28 mm, for example, for wide-mouth PET bottles - up to 60 mm) and a method of storage, depending on the operating conditions of the final product in the consumer market of a particular country, as well as on the structure of the distribution network. Whether the beverage manufacturer has set up production of its own preforms, whether it is a single-phase or two-phase process, or is acquiring them on the side, the next step for it will be the production, that is, blowing, of PET bottles as such.

PET bottle blowing
The internal design and performance of equipment varies greatly from manufacturer to manufacturer, but the basic principles of how it works remain the same. The choice of this or that equipment is dictated by the necessary and volume of production, the layout of the equipment at an existing enterprise and, of course, the price.

The simplest option is manually loaded machines, in which the preform heater and blow unit are actually separate parts. This type of equipment is intended for beverage producers with very small production volumes, since they are quite cheap, but they have sufficient productivity, which, as a rule, is 1000-1200 bottles per hour for machines of this type in a unit with two cells for blowing 1-liter bottles . Features of production may require equipment, which is an automated line. In this case, from one end of it, the molds are automatically loaded into the machine, and from the other, ready-made bottles come out, which again are automatically fed directly to the bottling line. Usually, in units with this configuration, the preform heater is in the form of a bracket, vertical or horizontal, which is done in order to save space. Rotary machines consist of a constantly moving wheel that guides the preforms through the heating section, from where, after appropriate temperature equalization, they are blown. Here, the preforms are loaded into empty cells as they pass the conveyor, go through the blowing stage, and the bottles are forwarded when the carousel rotates 360". The cell is now ready to receive a new preform.

PET bottle manufacturing steps

high speed rotary machine
In order to explore the above three stages of bottle blowing in more depth, let's turn to a modern rotary PET bottle making machine. Rotary machines have the advantage of saving production space due to their compactness. The preforms can be loaded from the same side as the finished bottles, leaving the other three sides of the machine free for access and inspection. There are also machines into which the preforms are fed directly opposite the place where the bottles exit: such equipment is designed to be included in a chain of automatic production lines. The possibility of positioning the rotary heating section above the blowing section and thus using the height resource, saving space, also speaks in favor of the compact external design of this kind of equipment.

Process Overview
In a conventional high-speed rotary SBM machine, the preforms from the main feed hopper are fed by a lifter to the distributor, where they automatically take the position necessary for their entry into the system, and then rise up the spiral lifter. The feed spiral positions the preforms correctly and forwards them to the main working compartment of the machine, where they enter the feed gear wheel. Each preform is caught by the ring on the neck with special pins and in an inverted position is fed to the heating carousel, which carries them through the heating chamber. There they reach a temperature that makes them soft enough for further blowing into a full-size bottle. Inside the heating chamber, the preforms constantly rotate around their axis, so that the heating is uniform. After leaving the heating chamber, the heated preforms are left for a certain time to equalize the temperature, and then fed into open molds for bottle blowing. These forms are located next to the heating chamber or under it. Once the mold is closed, the preform is immediately pulled out and pre-inflated. Stretching is performed mechanically using a special stretching rod, which is inserted into the neck of the future bottle and lowered down towards its bottom. As a result, the softened preform elongates. The depth of the stroke of the rod is mechanically adjustable and depends on the size and shape of the future bottle. Then, for a second, the blowing phase continues at very high pressure, during which the bottle takes on its final shape. The stretching rod is removed, the bottle is cooled, after which the mold opens and releases the finished bottle.

Heat
Before the preforms are fed into the heating section, they are still checked by an automatic quality control station on the supply spiral. The neck, further intended for capping with a cap, and the cross section of the preform are checked. At this stage, preforms with a defective neck or showing insufficient ovality are rejected. During the heating process in a typical SBM machine, preforms placed on special rods pass through an infrared heating chamber, where they reach the temperature necessary for stretching and blowing. The preforms are sequentially passed through a series of heating blocks consisting of infrared heaters with reflector plates that prevent heating of certain areas of the preform. This is especially important because, despite the fact that the whole preform is heated except for the neck, the blowing process requires that different zones of the preform have different temperatures. Only in this case the bottle will turn out as planned. The size and shape of the bottle being blown are factors that determine the so-called temperature profile, that is, the temperature regime for individual sections of the preform during its transformation into a bottle. Equipment manufacturers should provide sufficient installation flexibility temperature regime in order to ensure the best bottle quality at the end. To vary the temperature profile, each heating block in the heating chamber is equipped with nine separate vertically stacked heating elements that heat different areas of the preform. The degree of their heating is regulated independently from each other from the control panel, which allows the operator not only to set one or another temperature profile, but also gradually, with the passage of the preform through the heating zone, to increase the temperature. The area of ​​the preform adjacent to the neck often requires more heat to reach the desired temperature than other areas. Thus, the elements "responsible" for this zone should be more powerful and more numerous. The neck, already fully formed at the preform manufacturing stage, is protected from heating by a water-cooled screen. The number of heating blocks and the speed at which the preform passes through the heating chamber depend on the number of blow molds in the machine and the weight of the preforms to be heated. Since PET is a poor conductor of heat, it is necessary to cool the outer surface of the preform when it is between the heating blocks of the heating chamber. Otherwise, the surface would overheat, which could lead to unwanted crystallization. This intermediate cooling is carried out by means of air pumps located between each heating block. Thus, on the one hand, the preform is gradually heated, and on the other hand, its surface is constantly cooled.

Balancing
After heating to correct the temperature profile, the preforms undergo a special processing step aimed at balancing the temperature (equilibration). Equilibration, in essence, means the temperature distribution of PET in direct proportion to the wall thickness. This milestone which must be carefully calculated. If the equilibration period is too short, the bottle walls will be uneven in thickness. If the period is too long, the carefully controlled temperature profile will be disturbed, and in this case too much heat will enter the neck area, causing deformation of the latter during subsequent processing. Bottle blowing is carried out at a temperature of about 110°C.

Blowing and stretching
The preheated preforms are then conveyed along an inclined feed wheel to the blowing section, which in our case is located directly below the heating section. The feeder ensures that the preforms are correctly positioned in relation to the molds into which they are fed at high speed. The time required to heat up the preform is significantly longer than that required for stretching and blowing. This leads to the fact that there are always more preforms in the heating chamber than in the molds, so the wheel transporter is a necessary device in a high-speed SBM machine.

"Classic" shape for PET bottle
It consists of three parts: two side walls that open in a vertical plane, and a base that moves up and down. Once the preform is in the correct position, the mold is closed. The movable base (bottom) moves up, and the walls close around it. All this happens at the same time: the three components are connected firmly. At the same time, the tension rod starts its downward movement. Because it is in the position needed to start stretching the preform, the moment the mold slams shut, the cycle time is reduced and heat loss is reduced. The preform is stretched in a vertical plane and pre-blown at a pressure of 25 bar. The bottle at this stage is blown to 80-90% of its full size. Since it is very important not to damage the neck, the machines are equipped with special nozzles through which air is supplied. They are made in the form of a bell and protect the neck and the adjacent part from damage. High pressure (40 bar) is then applied and at this stage the bottle takes on its final shape. Pressing against the cold walls of the mold, the bottle cools down, becomes quite rigid and thus ready to leave the mold immediately when it is opened. To avoid wall distortion, the pressure inside the bottle is stabilized before the mold is opened.

"Relaxation"
After cooling and during storage, PET bottles shrink a little, so the machine controls the cooling of the bottle by heating the mold. This is done so that the material "rests" and the bottles are further compressed less intensively. This minimizes the difference in size between bottles released at different times, which is important when filling: the difference in the size of the bottles being filled can cause unforeseen difficulties in the operation of filling equipment. In machines where this feature is provided, the mold conveyor is isolated to conserve energy. SBM machines are available in numerous varieties, including those with a rotary mechanism, have from 6 to 24 bottle blow molds and produce an average of 1,200 bottles per hour per mold. The maximum productivity of the machine with 24 molds is 33,600 bottles per hour. Productivity, of course, depends on the size of the bottle being blown, since it takes more time to produce a larger bottle. A typical SBM machine is capable of producing bottles from 0.25L to 2.5-3L without additional conversion.

Quick mold change
The machine we have chosen as an example, like most SBM machines, uses standard three-part molds that are mounted on a mold transporter and can be quickly replaced with others designed to produce other bottles. The pull rod is controlled by a template, and the depth of its stroke is easily changed depending on the depth of the mold. It is estimated that a 10-mould SBM machine can be converted to produce a different bottle variety within 30 minutes by three technicians. During this time, all necessary settings are changed. Even if it is supposed to produce a completely different bottle with a different neck shape, the changeover will not take more than an hour.

Control
The operation of all the essential elements of both the rotary machine described above and the "linear" machine, such as the blowing station, the heating wheel, the preform conveyor and the mechanism that feeds the heated preforms from the heating chamber to the bottle blowing section, must be precisely synchronized using a single control systems. It is also necessary that each of these elements can be removed independently of the others for maintenance and readjustment. This mechanism is especially important for rotary machines. The machine is controlled using the touch panel. In modern machines, as a rule, the settings for different types of bottles are stored in memory and can be immediately activated by simply pressing a button. Naturally, during operation, the equipment gets a little out of order, but the heating and blowing parameters are automatically returned to normal mode. The monitoring system constantly monitors the operation of the machine, signaling the operator of any failures. Removal of defective preforms is also carried out automatically, and is carried out without stopping the machine. If the mold is left empty due to the removal of the preform, no pressure is applied to it, as is the case when the mold did not close properly. The touch control system can be electronically protected from unauthorized access.

Bottle transport lines
So, the bottle is made and thus ready for further use - bottling. PET bottles are very light and therefore unstable when not filled with contents. Naturally, this property was taken into account by equipment manufacturers when designing lines supplying empty containers for bottling. The light weight of the bottles allows them to be carried by the neck ring when filling, which minimizes the need for equipment adjustments, since the pouring height can be calculated from the neck of the bottle to the collar on the neck, and this distance remains the same on all bottles of a given lot. In addition, empty bottles can be moved not only with conventional transport lines, but also with the help of air. In the latter case, the instability of the bottle does not create problems. Empty bottles move on rails with low friction, being "supported" by the air flow by the ring on the neck. The rails are shaped so that air can flow along them. The jet of air lifts the ring on the neck of the light PET bottle and sets the transported container in the required direction. The advantage of this transport method is that the bottle does not come into contact with the sides of the transport belt. Today, this method of transportation is used on most of the manufactured and operated equipment.

PET BOTTLES RECYCLING

In Europe, the recycling of PET bottles is put on a state basis. For the CIS countries, the disposal of used PET containers is an environmental problem. Although the PET bottle is environmentally friendly, when burned, polyethylene terephthalate releases a large amount of carcinogens. A safer and much more profitable solution is to recycle used PET containers. In England today 70% of PET bottles are recycled, in Germany - 80-85%, in Sweden - 90-95% (this is the highest figure in Europe). The principle of state regulation of the processing of PET containers is that its manufacturers pay a special tax, which includes the cost of future processing. From this money, the state finances recycling. The construction of one recycling plant can cost up to? 50 million. The recycling process includes mechanical recycling (crushing) and chemical recycling (crushed parts decompose into their constituent parts). Each of the obtained components goes through a purification stage. The process of obtaining recycled PET is completed by granulation. The resulting granulate has a lower viscosity than the primary one, that is, its quality is already lower. Such PET granulate finds application in various fields - in the production of preforms, the addition of up to 5-10% of secondary raw materials is allowed, and it also produces good raw materials for the textile industry, the manufacture of tiles, euro pallets, and cotton wool. From recycled PET, after adding fiberglass to it, abrasive wheels are produced for grinding and polishing. The Ford company casts engine covers for trucks, and Toyota casts panels, bumpers, car doors from polymer compositions containing recycled PET.

On the post-Soviet territory, PET bottles are not recycled en masse. So far, only individual attempts have been made to produce paving slabs from recycled PET, and technologies have been developed (but not implemented) for the production of various heaters and building materials from recycled polyethylene terephthalate.

According to the materials of the journal "Pivnoe delo" and "Industrial Encyclopedia"