How to vulcanize rubber – Vulcanizing rubber at home

What does the term “tire vulcanization” mean?

Long service life and poor quality of roads do not have the best effect on the condition of car tires.
The aggressive influence of external factors leads to the formation of damage on their surface. The best option in this case is to go to a service station, where specialists will vulcanize the tires. Vulcanization is a high-tech process in which rubber is formed into rubber. This raw material allows you to significantly minimize the cost of maintenance and repair work on tires.

Any auto repair shop offers several vulcanization options:

• hot - “raw rubber” can be heat treated and attached to the cut area;
• cold - a selected patch and adhesive are used.

The first type of problem repair is more effective and reliable, since the wheel can be used in a normal environment for a long time. The second type is most often used as a temporary bookmark. According to the instructions, vulcanization can be used for the following cuts: for transverse cuts - up to 25 mm, longitudinal cuts - up to 35 cm.

"Hot vulcanization"

The “hot vulcanization” method is based on treating the cut with rubber using high temperatures. Thermal action allows the rubber components to be transformed into one monolithic layer. The procedure takes on average 1-2 hours (depending on the level of damage).

Hot vulcanization includes several stages:

1. Removing the tire and processing the cut with a milling cutter.
2. Covering the previously treated area with protective agents.
3. The thoroughly dried area is evenly filled with rubber and sent to a specialized machine.
4. Vulcanization of the tire is carried out at a temperature of 120-140 degrees.
5. Applying a cord patch to improve technical characteristics.
6. Finishing the tire and installing it in place.

Prices for such a procedure range from 400 rubles and directly depend on the radius of the tire, a specific region and the cost of raw materials.

"Cold vulcanization"

This method does not require heating and is used in emergency situations. The patches or so-called strands are held together using “cement.” Cold vulcanization is carried out as follows:

1. Removing the wheel and visually diagnosing the cut.
2. Degreasing and cleaning damage.
3. Glue is applied to the treated area.
4. The wheel is inflated and mounted back.

The preliminary cost of this procedure is 250 rubles (everything depends on the brand of materials used and the degree of complexity of the damage).

Tire reliability after repair work

• Repairing side and longitudinal cuts on a tire using vulcanization can significantly extend the service life of the tire. If the technical requirements are met during the process, the repaired wheel can last several more seasons under the conditions of daily vehicle use.
• Cold vulcanization should be used exclusively with high-quality adhesives. In particularly difficult cases, it is necessary to bead the wheel and apply an additional patch to the inside of the tire.
• The most common defect that appears as a result of unprofessional work is the appearance of a hernia on the sealed area of ​​the tire. They also immediately require repair and intervention by specialists. If the problem occurs again, it is recommended to replace the components.

Wheel balancing after vulcanization

Vulcanization affects the structure of the wheel, shifting its center of gravity to the side. This leads to an imbalance of application vectors, which can affect ride quality and lead to an emergency situation. In addition, the following may happen:

• Premature wear of the suspension and tread;
• increasing braking distance;
• unpleasant vibrations in the steering system.

To reduce all possible risks on highways, it is necessary to balance tires immediately after vulcanization. Wheel balancing is carried out on a specialized machine. More effective results can be achieved through the use of innovative electronic stands.

PS Despite this, some car enthusiasts believe that the correct way to repair a tire with a side cut is to take it to the trash heap and buy a new one. Repairing a side cut is only permissible on tires for agricultural and special equipment where speeds are low. The choice is yours alone.

§ 2. Production of shoe rubber plates and parts

The technological process for the production of shoe rubber plates and parts consists of the following operations: preparation of raw materials; production of rubber compounds; obtaining raw rubber blanks; vulcanization of plates and parts; finishing of vulcanized products.

Preparation of raw materials and materials

The composition of the rubber mixture includes: powdery and resinous substances (fillers, softeners, vulcanizers, vulcanization accelerators, antioxidants, blowing agents, etc.), regenerate and rubber.

All these materials undergo appropriate preparation and processing before being introduced into the mixture.

The powdered components of rubber compounds are dried (if their moisture content exceeds established standards), crushed and sifted. The need to remove excess moisture from powdered components is explained by a number of reasons: the use of wet materials contributes to the formation of lumps in the manufacture of rubber compounds and makes it difficult to distribute the components evenly in the mixture; during vulcanization of mixtures, bubbles form in the finished products due to moisture evaporation; The high humidity of kaolin makes it difficult to process the rubber mixture.

Powdered components are crushed and sieved to obtain particles of the smallest possible and, moreover, uniform size; When the grinding and sifting operations are carried out correctly, their uniform mixing with rubber and other components of rubber compounds is facilitated.

Resinous solids are first cleaned of adhering foreign substances and then crushed into small pieces or, in some cases, melted.

The regenerate is selected according to color, method, regeneration and feedstock and then cut into pieces of the required sizes.

Natural rubber is heated to 60-80° C, cut into pieces and sent for plasticization, which is carried out on plasticizing rollers, in closed screw-type plasticizers and in rubber mixers.

Plasticized natural rubber differs from unplasticized natural rubber in its greater plasticity, as a result of which it mixes faster and better with powdered and other components of the rubber mixture; Plasticization increases the homogeneity of the rubber. Rubber mixtures made from plasticized natural rubber are better calendered and extruded on worm presses.

To uniformly distribute the individual components in the rubber mixture and facilitate their mixing, preliminary (before final mixing) production of so-called mats and pastes is practiced, i.e. mixtures containing only individual components (for example, rubber-polystyrene mats, consisting of rubber and polystyrene, rubber uteri of accelerators or dyes, paste of blowing agents or sulfur with petroleum jelly or other oil).

Production of rubber compounds

The process of mixing rubber with the other components of rubber compounds is carried out in accordance with a given recipe, an established sequence of feeding individual components for mixing and a regulated mixing mode.

Rice. 58. Mixing rollers

Previously, mixing rollers were used for mixing (Fig. 58). The main part of these rollers, as well as the rollers used for plasticizing rubber and sheeting of rubber compounds, are two hollow cast-iron rollers 1 and 2 with a smooth surface, rotating towards each other at unequal speeds. Depending on the purpose, cold water or steam is passed through the internal cavity of the rolls. As the rollers rotate, they draw the rubber into the gap between them and intensively mix it with the rest of the rubber mixture.

Rice. 59. General view of the rubber mixer

Due to low productivity, high energy consumption and other disadvantages, mixing on rollers has been replaced by mixing in rubber mixers. The rubber mixer (Fig. 59-60) consists of a foundation plate on which the mixing chamber housing is installed. Inside the housing there are two hollow rolls with a helical surface and an oval cross section. The rollers rotate in the mixing chamber towards each other at different speeds; Thanks to this, the rubber mixture is captured by the roller blades, repeatedly mixed and ground by them. The mixture is also carried between the roller blades and the chamber walls.

Rice. 60. Diagram of the rubber mixer: 1 - foundation slab; 2 — mixing chamber body; 3 — lower (outlet) valve; 4 - rolls; 5 — loading funnel; 6 — hinged lid of the loading funnel; 7 - upper shutter; 8 — rod of the upper shutter; 9 - piston; 10 — upper shutter chamber; 11 — walls of the mixing chamber; 12 — tubes for water supply

To prevent the rubber mixture from heating above the optimal temperature determined for each mixture, the walls of the mixing chamber are cooled with water coming from tubes, at the ends of which there are nozzles that spray water. The rollers, as well as the upper and lower valves of the rubber mixer, are also cooled by running water entering their internal cavities.

When producing rubber compounds, rubber is initially loaded, then regenerate and softeners are added, then accelerators, accelerator activators, dyes, fillers and blowing agents are added. To prevent premature partial vulcanization of rubber compounds, sulfur is introduced at the end of mixing or during subsequent processing of the mixtures. The duration of mixing rubber compounds in a rubber mixer is usually 8-12 minutes.

One-time removal of rubber mixture from the rubber mixer
is 175-220 kg.
In addition to rubber mixers, continuous worm mixers are used for the production of rubber mixtures.

The mixture unloaded from the rubber mixer in the form of irregularly shaped pieces is fed to sheeting rollers, arranged similarly to plasticizing and mixing rollers. On sheeting rollers, the mixture is processed into flat sheets, and sulfur is also introduced into the mixture (if it was not introduced in the rubber mixer).

In the production of porous and leather-like rubbers, the rubber mixture is additionally processed on refining rollers; intensive grinding of the rubber mixture between the rollers of these rollers, heated to 70-80° C, shifted closely together, increases the homogeneity of the mixture and improves the physical and mechanical properties of the rubber.

Obtaining raw rubber blanks

The most common method of obtaining raw rubber blanks is calendering the rubber mixture, followed by cutting or cutting plates and parts of the required shape and size from the calendered tape.

Calendering gives the rubber mixture the shape of a tape of a certain width and thickness. Before calendering, the rubber mixture is heated to increase plasticity by processing it on heating rollers for 4-10 minutes.

at a temperature of 50-80 ° C. If sulfur and blowing agents have not previously been introduced into the rubber mixture (in a rubber mixer or on sheet rollers), then the operation of heating the mixture is combined with the operation of introducing sulfur and blowing agents. The softened rubber mixture is fed to a three-roll sheet-coating calender (Fig. 61, a).

The calender consists of a frame and three (or more in multi-roll machines) steel hollow rolls of the same size, located one above the other and mounted in bearings.

The rollers rotate at the same or unequal speed. To heat or cool the rolls during the calendering process, steam or cold water is supplied to their internal cavity. The surface temperature of the rollers, depending on the type of rubber mixture being processed, is maintained from 60 to 100° C.

Rice. 61. Three-roll sheet-lubricating calender (a) and rubber mixture calendering scheme (b)

In three-roll calenders, the rubber mass enters the gap between the upper and middle rolls, then passes to the lower roll through the gap between the middle and lower rolls, goes around the lower roll and is removed from the latter in the form of a tape (Fig. 61, b).

During the calendering process, under the influence of forces arising when the rolls rotate towards each other, the rubber mixture is stretched. Due to the orientation of the structural elements of the rubber mixture when it is drawn, the rubber tape, as well as products cut from it, have unequal physical and mechanical properties in the longitudinal and transverse directions (calender effect).

The tape removed from the calender is powdered with either talc, zinc stearate, or rubber flour to prevent sticking. Raw rubber blanks are cut from a calendered belt in different ways (cutting into separate plates with subsequent stamping, stamping of the tape on automatic presses, etc.). When cutting soles from a calendered belt, they are placed across the calendering line, since this achieves greater elongation of the soles in the longitudinal direction and increases resistance to repeated bending during shoe wear.

In addition to calendering the rubber mixture to obtain raw rubber blanks, especially in the manufacture of porous leather-like rubbers and heels, they also use the method of squeezing the rubber mixture from the cylinder of a worm press through a profile hole in its head, followed by cutting the extruded tape into individual blanks. Worm presses are equipped with replaceable heads and other replaceable devices used to produce rubber products of various shapes and sizes. To regulate the temperature of the mixture during processing, steam or cold water is supplied to the cylinder jacket and press head, as well as to the cavity of the worm.

Rubber mixtures intended for the production of footwear using the press vulcanization method have recently been produced not only in sheets, but also in granules.

Vulcanization of rubber blanks

Vulcanization is the process of changing the properties of a rubber mixture as a result of the interaction of rubber with sulfur; in vulcanized rubber, part of the sulfur is chemically bound to the rubber, the other part - free sulfur - is relatively easily extracted from the rubber. Only after vulcanization does rubber acquire most of those properties that determine the value of rubber products and their widespread use in modern technology and everyday life.

The changes that occur in rubber during vulcanization are often collectively referred to as “structuring.” By structuring we mean the mutual adhesion (“cross-linking”) of the molecular elements of the rubber structure with each other, leading to a complication of the structure and a decrease in the mobility of its individual elements. The structuring of rubber is associated not only with its chemical interaction with sulfur, but also with other complex phenomena.

The change in the properties of the rubber mixture during the vulcanization process occurs gradually: the strength, hardness and elasticity of the rubber increase, its elongation at break decreases, etc. After a certain period of time, called the optimal vulcanization time, the most favorable combination of rubber properties is achieved in all quality indicators. If the vulcanization of rubber blanks stops before the optimal time, then the finished products turn out to be under-vulcanized; on the contrary, when the vulcanization time increases compared to the optimal one, rubber products become over-vulcanized and their properties deteriorate. The vulcanization period during which the optimal properties of rubber products are maintained is called the vulcanization plateau. The more extended the vulcanization plateau, the less likely it is that rubber products will overvulcanize or undervulcanize.

Vulcanization of rubber parts for the bottom of shoes is carried out by heating blanks of the rubber mixture in molds placed in a vulcanizing press (Fig. 62). It consists of an upper traverse connected to a cast lower base through columns. Steel plates, heated from the inside by steam, are located between the upper traverse and the base, forming four to six storey spaces into which rubber blanks are loaded in molds. Lifting of the press plates and pressing of products is carried out respectively with water or low- and high-pressure mineral oil.

Rice. 62. Vulcanizing press: a - general view; b - vulcanization diagram of a raw rubber blank; 1 — press plates; 2 - mold; 3 - vulcanizable raw rubber blank

When manufacturing rubber products in the form of plates, raw rubber blanks are loaded into the simplest molds - press frames, which are rectangular metal frames with a covering sheet; The outer dimensions of the press frame and cover sheet correspond to the dimensions of the press plates, and the inner dimensions correspond to the dimensions of the resulting rubber plate. Vulcanization of rubber products in the form of individual parts is carried out in more complex multi-place metal molds (Fig. 63), consisting of two or three parts; The internal mold cavities fully correspond to the size and shape of the parts being manufactured.

The mold shown in Fig. 63, a, consists of two parts: body 1 and cover 2. In the mold body, which is a heavy steel plate, there are sockets (recesses) 3 for soles, alternating with recesses 4, which serve to release excess rubber mixture. There are sides 5 around the nests for the soles. For ease of movement of the mold, handles 6 are made on both sides,

In Fig. 63, b shows one of the molds for vulcanization of molded heels. It consists of three parts: the middle 7 with through sockets that define the contour of the heels, the bottom 8 and the top 9, which define the lower and upper surfaces of the heels, respectively. On the lower part of the mold there are sockets 10 that form the running surface of the heels, and on the upper part there are convexities 11 that form the concavity of the upper platform of the heels. For precise alignment of all three parts of the mold, guide holes 12 and pins 13 are used.

The internal surfaces of press frames and molds are polished or chrome plated; individual surfaces of the mold sockets are engraved to obtain a relief pattern on the corresponding surfaces of the rubber products.

Rice. 63. Mold design: a - for vulcanization of profiled soles; b - for vulcanization of molded heels

After filling with rubber blanks, molds or press frames are closed with lids and placed on heated plates of a vulcanizing press. During subsequent pressing, under the influence of high pressure exerted by the press plates, the rubber mixture fills the mold cavities and takes on the required shape, and the excess mixture flows out to the sides, forming an extrusion. Molds with rubber parts are kept in the press for a certain time required to complete the vulcanization process.

The duration of keeping the molds in the press, which determines the vulcanization time, varies depending on the composition of the rubber mixture, the purpose of the rubber products and other factors, ranging from 5-6 to 10-15 minutes or more at a vulcanization temperature of 140-170 ° C and a pressure on the mixture of 350 -500 n/cm2

.

The vulcanization mode in the manufacture of porous rubber products has a number of features arising from the combination of the processes of pore formation and vulcanization. When vulcanizing porous rubber products, it is important that the decomposition of pore-forming substances during the heating of the rubber mixture precedes the loss of its plasticity. This condition can be satisfied by the appropriate selection of pore-forming agents and vulcanization accelerators (the decomposition temperature of pore-forming substances must be below the critical temperature of the accelerators) and the vulcanization mode. For the manufacture of porous rubber products, two vulcanization methods are used: the growth method and the alternating pressure (alternating pressure) method.

When vulcanizing using the growth method, workpieces with a volume smaller than the volume of the mold nests are placed into the mold cavities. The latter are placed on the plates of a vulcanization press and pressed under constant pressure until vulcanization is completed. During the initial period of keeping rubber blanks in the press, under the influence of heating, pore-forming substances decompose, which leads to an increase in the volume of the blanks by 1.5-2.0 times or more and filling them with the entire internal volume of the molds. After the completion of the mold filling period, which lasts several minutes, the process of vulcanization of the resulting porous rubber product begins. The total duration of holding molds with rubber blanks in vulcanization presses, depending on the type of vulcanized products, ranges from 8-18 minutes or more, vulcanization temperature 150-160 ° C, pressure - up to 50 n/cm2

. The porosity of rubber products, in addition to the composition of the rubber mixture, is determined by the growth method by the relationship between the thickness of the raw blanks and the height of the mold cavities. Growth vulcanization is used to produce black porous rubber products.

When vulcanizing using the alternating pressure method, workpieces with a volume exceeding the volume of the mold cavities are placed into the mold cavities. of 250-300 N/cm2 is first applied

.
In this case, the blanks fill the cavities of the molds, and the excess mixture flows out of the mold in the form of extrusion. During this period, despite the heating of the workpieces, pore formation in the rubber mixture does not occur due to high external pressure. When the pressure in the press decreases to 10-30 n/cm2
, the molds move slightly apart, the volume of the rubber blanks increases, since the internal pressure of the gaseous products of the decomposition of pore-forming substances exceeds the external pressure on the vulcanized blanks.
Vulcanization of the workpieces is completed at low external pressure. The total duration of vulcanization by alternating pressure at a temperature of 150-160° C reaches 15-18 minutes
. When vulcanizing using the alternating pressure method, small, uniform pores are formed in rubber blanks, and when using the growth method, larger and less uniform pores are formed. The porosity of rubber products vulcanized by alternating pressure is regulated by the ratio of the duration of holding molds with rubber blanks under high and low pressure. The disadvantages of vulcanization using the alternating pressure method are large fluctuations in the thickness of products and the difficulty of obtaining rubber molded parts with precise specified linear dimensions. Pressure alternating vulcanization is widely used in the production of various lightweight colored porous rubber sheets for shoe bottoms, as well as leather-like porous sheets.

Leather-like porous plates are also vulcanized at constant high pressure in press frames of increased thickness, followed by sawing into two or more layers of the required calibers, since the direct production of porous rubber products of small thicknesses is very difficult. To protect rubber products from over-vulcanization, and porous products also from further pore formation inside the rubber and changes in their dimensions, vulcanized rubber blanks are subjected to cooling after unloading from the molds.

After cooling, porous rubber products are subjected to heat treatment at 100-110° C for 2.5-3 hours

to reduce area shrinkage during shoe production.

Cooled rubber products are sent for trimming of extrusions (burrs) using special machines, then for sorting, branding and packaging.

Certain types of rubber products after vulcanization are subjected to more complex processing: sawing (splatting) into separate layers of rubber plates, cutting out sole, heel and other parts from plates, removing the upper platform in porous stamped heels, etc.

Rubber products for the bottom of shoes are stored on racks in ventilated dark rooms at a temperature of 0 to 20 ° C at a distance of at least 1 m

from the heating system.

In recent years, much work has been carried out in the USSR to improve the technology and automation of the production of shoe rubber products. Automatic rotary vulcanization presses have been developed and implemented; production lines for the production and processing of rubber compounds have been mastered and are successfully operating; fundamentally new methods of manufacturing rubber shoe parts are being introduced by casting rubber mixtures under pressure in special vulcanizing units; The range of manufactured shoe rubbers and rubber parts has been significantly expanded based on the use of various types of synthetic rubbers, etc.

Defects and grading of shoe rubber products

Defects of rubber products for the bottom of shoes.

Defects in rubber products occur at various stages of production. Below is a brief description of the most common defects in rubber products for the bottom of shoes.

Foreign inclusions

— particles of metal, wood, sand, etc., located on the surface and inside rubber parts, arise when the operations of hanging and mixing the components of rubber compounds are carried out carelessly, as well as as a result of contamination of the latter during transportation.

Bubbles, shells, large pores

on the surface of rubber products and inside them are formed due to high humidity of individual components of the rubber mixture, uneven mixing of pore-forming agents, air entrapment in the rubber mixture during the calendering process, etc.

Uneven surface, dents, pockmarks, rashes, prints, roughness

- all these surface defects are formed as a result of the use of coarsely ground powdery components of the rubber mixture, poor cleaning of the molds, the presence of nicks and scratches on the inner surface of the molds, etc.

Uneven color, dirty surface, stains, marbling

(characteristic wavy spots with a color reminiscent of the surface of marble) are the result of improper mixing of the main components of the rubber mixture with dyes and pigments, as well as the rubber mixture with added cuttings from other mixtures, the use of poorly cleaned molds, oil getting into the rubber mixture, etc.

Sulfur fading

, manifested in the formation of a light gray fine-crystalline coating on the surface of rubber parts, occurs when the rubber mixture is under-vulcanized and there is little binding of rubber with sulfur due to the incorrect selection of softeners.

Underpressing

(lack of the exact shape of rubber products),
deviations in the size of the edges of the welt and heel, unclear patterns on the surface of the products and welt, shift of the welt
, etc. occur when there is insufficient pressure during the vulcanization process, with low plasticity of the rubber mixture, insufficient filling of molds with rubber mixture , due to malfunction of molds and displacement of their individual parts, poor cleaning of molds.

Undervulcanization

outwardly expressed in excessive softness and plasticity of rubber products; Under-vulcanization of rubber products is caused by insufficient dosage of sulfur, vulcanization accelerators or their activators, insufficient duration of vulcanization or low temperature of the vulcanization press plates.

Revulcanization

products, causing their increased rigidity and often fragility, is caused by reasons opposite to under-vulcanization.

In addition to the listed defects, there are others in rubber products for the bottom of shoes: deviations in the size of parts, uneven thickness in individual parts, as well as in a batch of parts, irregularities in the location of holes for nails in heels, etc.

Determination of the grade of rubber products for the bottom of shoes.

Depending on the nature and size (extent) of defects, shoe rubber plates and parts are divided into graded and non-grade. Graded plates include plates that do not have defects or have a limited number of defects; the number of plates with defects should not exceed 15% of the total number of plates in the batch.

Graded rubber parts (soles, heels, heels, etc.) include parts that do not have defects or have no more than two (acceptable), the location and dimensions of which do not affect the technological and operational properties of the parts.

When accepting stamped and molded rubber parts, their dimensions are checked for compliance with the drawings and control templates. To determine compliance with the dimensions of the drawings, parts of various sizes and different mold numbers are selected (the mold number is indicated on the reverse side of the parts) in quantity

where x is the number of selected parts in pairs;

n is the number of numbers (sizes) of parts in the size range;

N is the total number of parts in the batch.

Production of raw rubber

Rubber is used as the basis for the production of this raw material; it can be either natural or artificial rubber. The following substances can be used as plasticizers:

sulfur;

gas soot;

sand (silicon dioxide);

and many others.

The main properties of this raw material are provided precisely by its components. Sulfur, which is part of the molecular structure, is responsible for its hardness. Soot and oils give the finished part elasticity. Other components improve wear resistance and strength. Almost all raw rubber is produced on the basis of GOST and TU, for example, TU 38-105-1082-86. But in practice, you can purchase everything you need to make raw rubber with your own hands.

Production of raw rubber

The finished product is delivered to the customer either in the form of sheets or tape wound into a roll.

After mixing the components, the resulting mixture is sent to rollers or calenders, and on this equipment rolls or sheets are formed. After passing through this machine, the rubber mixture takes the form of a sheet, the required width and height.

This raw material also exists in liquid form. In appearance, this substance resembles honey, with the difference that it is black in color.

After receiving a sheet formed from a pre-prepared mixture, it is covered with a polymer film. It's all about the stickiness of this raw material.

Raw rubber covered with polymer film

Instructions for the production of raw rubber provide modes that allow the production of high-quality raw materials at low costs.

This raw material can be used to seal holes in inner tubes, boats and other rubber goods. For this purpose, the cold vulcanization technique is used. As a result, the hole will be sealed, but not for long. To perform a complete repair, ensure that the raw rubber is hot vulcanized. In this case, the formation of long-sized molecules bound together by sulfur occurs. Repairs using hot rubber vulcanization technology are widely used at car service stations. The production of almost all types of rubber technical products occurs at a vulcanization temperature of raw rubber of 150 degrees Celsius.

Special purpose rubbers

Special rubbers are divided into several types: oil- and petrol-resistant, heat-resistant, light-ozone-resistant, wear-resistant, electrical, and resistant to hydraulic fluids.
Oil and petrol resistant

Rubbers are produced on the basis of chloroprene rubbers (nairit), SKN and thiokol.
Nairit
is a domestic chloroprene rubber. Chloroprene has the formula CH2=CCI-CH=CH2. Vulcanization can be carried out by heat treatment even without sulfur, since under the influence of temperature the rubber passes into a thermostable state. Nairite-based rubbers have high elasticity, vibration resistance, ozone resistance, are resistant to fuel and oils, and have good resistance to thermal aging. (The oxidation of rubber is slowed down by the shielding effect of chlorine on double bonds.) In terms of temperature resistance and frost resistance (from -35 to -40 ° C), they are inferior to both NC and other SCs. The electrical insulating properties of rubber based on polar nairite are lower than those of rubber based on non-polar rubbers. (Polychloroprene rubber is produced abroad under the names neoprene, perbunan-S, etc.).

SKN

- butadiene nitrile rubber - a product of joint polymerization of butadiene with acrylic acid nitrile -CH2-CH =CH-CH2-CH2-CHCN- Rubbers based on SKN have high strength ((b = 35 MPa), have good abrasion resistance, but are inferior in elasticity to rubbers based on based on NK, superior to them in resistance to aging and the action of dilute acids and alkalis. Rubbers can work in the environment of gasoline, fuel, oils in the temperature range from -30 to 130 ° C. Rubbers based on SKN are used for the production of belts, conveyor belts, hoses , oil and petrol resistant rubber parts (sealing gaskets, cuffs, etc.).
Thiokols
are the trade name for polysulfide rubbers. The desired products are formed from a mixture of rubber with sulfur, fillers and other substances and subjected to heating. Under these conditions, sulfur atoms are attached to double bonds rubber macromolecules and “crosslink” them, forming disulfide “bridges.” As a result, a giant molecule is formed that has three dimensions in space - like length, width and thickness. The polymer acquires a spatial structure. If you add more sulfur to rubber than is needed to form rubber, then during vulcanization the linear molecules will be “cross-linked” in many places, and the material will lose elasticity and become hard - you will get ebonite. Before the advent of modern plastics, ebonite was considered one of the best insulators.

Polysulfide rubber, or thiokol, is formed by the interaction of halogenated hydrocarbons with polysulfur compounds of alkali metals:

...—CH2—CH2—S2—S2— ... Thiokol is vulcanized with peroxides. The presence of a sulfur macromolecule in the main chain gives the rubber polarity, as a result of which it becomes resistant to fuel and oils, to the action of oxygen, ozone, and sunlight. Sulfur also gives thiokol high gas impermeability (higher than NK), so thiokol is a good sealing material.

The mechanical properties of thiokol-based rubber are low. The elasticity of rubber is maintained at temperatures from -40 to -60 °C. Heat resistance does not exceed 60-70 °C. New brands of thiokols operate at temperatures up to 130 °C. Acrylate rubbers

- copolymers of acrylic (or methacrylic) acid esters with acrylonitrile and other polar monomers - can be classified as oil- and petrol-resistant rubbers. Rubbers are produced in the brands BAK-12, BAKH-7, EAH. To obtain high-strength rubber, reinforcing fillers are introduced. The advantage of acrylate rubbers is their resistance to sulfur-containing oils at high temperatures; They are widely used in the automotive industry. They are resistant to oxygen, quite heat-resistant, and have adhesion to polymers and metals. The disadvantages of BAC are low elasticity, low frost resistance, low resistance to impact; hot water and steam.

Wear-resistant rubber

are obtained on the basis of polyurethane rubbers SKU. Polyurethane rubbers have high strength, elasticity, abrasion resistance, and oil and petrol resistance. There are no unsaturated bonds in the structure of rubber, therefore it is resistant to oxygen and ozone, its gas permeability is 10-20 times higher than the gas permeability of NK. The operating temperatures of rubber based on it range from -30 to 130°C.

Urethane rubber is resistant to radiation. Foreign names for urethane rubbers are vulcollan, adiprene, jentan, urepan. Rubbers based on SKU are used for car tires, conveyor belts, pipe linings and gutters for transporting abrasive materials, shoes, etc.

Pros and cons of vulcanization

The main advantage of the tire repair process is that it is cheaper to repair than to buy a new one.

However, each situation is individual, so it is important to determine whether repairs will save the situation

The cold method is quite easy to use, it will not take much time, and the costs will be minimal. The main disadvantage of this method is the unreliability of gluing. This procedure is temporary, and you should contact a service station as soon as possible.

Hot vulcanization reliably welds rubber, allows such work to be carried out at any temperature and has a low cost.

So, you can repair a tube or tire in different ways, but it is better to entrust this work to specialists, because it is for your own safety.

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Is vulcanization possible at home? The question is by no means rhetorical, but one of the most discussed on forums among car and bicycle enthusiasts. Self-repair of rubber products - from a tire to a children's toy - will save time and money, and will give vent to the creativity and ingenuity of a true car enthusiast.

If we talk about “cold” vulcanization, then the materials for this simplest and quickest repair are a must-have in your travel first aid kit.

The essence of the hot vulcanization method is the hardening of the rubber mass under the influence of heat. Knowing what should happen in the end, and having a fair amount of patience, you can repair any camera at home and quite reliably - car, bicycle, football. You will need simple equipment (more on this later) and a piece of raw rubber (patch), previously soaked in gasoline.

“Home” vulcanization technology

A piece of raw rubber (from auto tube rubber) should be slightly smaller than the size of the patch. The tire at the point of damage is sanded (with a reserve) - this will improve the adhesion of the materials, and then cleaned with gasoline. The edges of the patch must be rounded (cutting off the end of the patch at an angle of 45 degrees), then also treated with sandpaper and degreased with gasoline (B-70 or Galosh). Then you should cover the damaged area with a paw, place it under a press and heat until hardened.

The most popular component of a home “vulcanizer” is the old one (a good Soviet one is the best option), using an electric stove with an open ceramic spiral. The main task facing the master is to create a reliable clamp connection in a home vulcanizing press.

Advice from the “experienced”

• Before applying the prepared patch to the cut site, lubricate it with glue. It is easy to prepare at home by dissolving raw rubber in gasoline.
• Get ready to gradually master this process. A very important point is maintaining the temperature regime. When the optimal temperature is exceeded, a characteristic smell of burnt rubber appears - your patch is “sintered”. If the patch does not merge with the cut, it means the vulcanization temperature was insufficient or the process was completed early.
• If the iron's thermostat works (this happens), you need to set the temperature to 140 degrees (or the designation for silk). This temperature regime prevents overheating of the patch and the product itself.
• To prevent the rubber from sticking to the metal during the vulcanization process, it is enough to lay a piece of paper.
• If water comes into contact with the vulcanizer and it boils, it’s time to turn it off. After waiting a little more, the vulcanizer can be removed, allowing the rubber to cool. Sugar is also used: if grains of granulated sugar begin to caramelize upon contact with the surface of the vulcanizer, the vulcanizer must be turned off.
• The product to be repaired is placed on a hot vulcanizer plate (heated iron) with the damaged area downward and kept for the technologically required time (10-15 minutes). After one or two ruined tires, everything will become clear and home vulcanization can be safely put on stream.

For cuts with a complex configuration, it makes sense to make a more complex mold from two sheets of steel 6-10 mm thick. The plates are tightened with screws using holes drilled in the corners.

When doing self-repair, there is a high probability of damage to the cord thread, which can lead to protrusion (herniation) of the rubber during operation. In addition, the wheel will be unbalanced; eliminating the imbalance at home is hardly possible. When the car is moving, such a wheel will make life very difficult for the driver.

Only a completely intact wheel can provide a 100% guarantee of safe driving. Therefore, it’s worth saving up and buying new tires.

Cement for vulcanization and its application

Another alternative option for repairing bicycle wheels while traveling is a can of cement vulcanizer. You can buy them, for example, at the car market - this material is very popular among car enthusiasts. The composition is sold in tin and aerosol cans under pressure from brands such as Abro, BL, Zefal, Top RAD and many others. In terms of their composition, they are not hazardous to health and are not toxic, because... they do not contain chloride and aromatic hydrocarbons, so they can be used freely both at home and outdoors without a protective mask. In order for tire cementation to occur, a temperature of 18 degrees Celsius is required. The composition is also used for hot vulcanization (150 degrees required). To repair, you need to remove the foreign object that caused the puncture from the rubber of the inner tube, fill the inner tube with a cement vulcanizer through the nipple, slightly inflate it with a pump and ride a bicycle for 2-3 kilometers to adjust the pressure in the wheels. This tire repair technology is simple and is also used everywhere. To consolidate the result, it is possible to use a patch of plaster followed by the hot vulcanization method - exactly the same as described in the instructions above. The technology is suitable for any tire cuts. In this case, the patch for repairing the tubes is applied before filling the tire with cement.

Hot vulcanization of tires - features and advantages

The process of hot vulcanization of tires is based on heat treatment of the damage site with the addition of rubber (“raw rubber”). Under the influence of high temperature, the rubber components are bonded together, creating a plastic monolithic layer.

Hot vulcanization of tires

Penetrating into the cut site, the heat-treated rubber completely fills the space, preventing dirt and moisture from penetrating into the tire.

Briefly, the hot vulcanization process is as follows:

1. The tire is removed from the disk, the cut area is carefully processed with a milling cutter (the main thing is not to damage the cord).
2. The treated area is additionally cleaned and degreased.
3. A special composition is applied to the cut site in 2 layers.
4. The dried damaged area is filled with “raw rubber” layer by layer, after which the tire is sent to a tire vulcanization machine. Heat treatment is carried out at a temperature of 120-140°C.
5. For additional strength, a special cord patch is applied to the inside of the tire.
6. After the rubber has cooled, the repair site is additionally cleaned with a milling cutter and finishing is carried out.

Advantages of hot vulcanization:

• Price. The cost of eliminating side cuts using this method is lower than buying new tires.
• Reliability. High-quality vulcanization of tires can preserve 90% of the rubber's strength.
• Efficiency of repairs. You can drive with the repaired wheel immediately after the damage has been repaired.
• The versatility of the method. Hot vulcanization can be performed at subzero temperatures in winter, as well as in highly dusty conditions. This means that in case of sudden cuts and the absence of a spare tire, you can call a mobile tire service that will repair the wheel right on the road.

Now about the time standards for tire vulcanization. It takes professionals 1-2 hours to complete a complete repair. Vulcanization of truck tires takes much longer – from 2 to 4 hours.

On average, the price of repairing a side cut of a tire using hot vulcanization starts from 400 rubles. and depends on the characteristics of the damage, tire radius, region and specific workshop.

Hot tire service

No matter how good cold vulcanization of tires is, it cannot seriously compete with hot vulcanization even in the 21st century. Of course, if we are talking about an ordinary bicycle or even a car camera, then yes - here such a tool will cope with a bang. If you need to vulcanize truck tires or need to repair the side cuts of the tire, there is only one way out - tire fitting under the influence of high temperatures.

Car enthusiasts began using this technology back in 1839, after a certain Charles Goodyear presented his invention to the world. The essence of the discovery was as follows: it was necessary to combine the damaged rubber element with a patch or patch of a similar composition so that the connection was strong and inseparable! Thanks to the creation of strong, unbreakable molecular bonds, this was possible, but to obtain them, the vulcanized elements must be subjected to heating.

Of course, in the modern world, professionals in this field have mastered the skill ideally. They have special equipment, thanks to which the guys can not only help motorists in trouble, but also earn good money.

If we have non-vulcanized rubber, we are left with a choice: go to a tire shop or do the repairs ourselves? Without a doubt, sometimes it’s just impossible without specialists, but no matter what, every self-respecting driver simply must know how to repair tires with his own hands! We'll talk about this further...

DIY tire vulcanizer

Any vulcanizer must consist of a press and a heating element.

You can even do it with your own hands, with ingenuity and skillful hands. You can make a unit:

• from a household iron;
• from an electric stove;
• from a piston from a car engine.

If you use an iron, its sole will serve as a heating element. A device with a thermostat would be ideal. A pipe can act as a press. Such a vulcanizing device will require a minimum investment of money and material.

Pay attention! If you use an electric stove, then in this case you will need to put a metal plate on the spiral. Before laying rubber on it, it is recommended to put paper on it so that the plate does not stick. You will also need to attach a thermostat here, which is set to turn off at 150°. Here you can also use a pipe cutter as a press.

A piston vulcanizer will become an indispensable assistant if a tire puncture occurs on the road, and there are no special materials for vulcanization and a socket at hand. This unit works according to the following scheme:

• The camera is placed on a flat metal surface.
• The damaged area is pressed against the bottom of the piston and firmly fixed.
• Paper is placed between the rubber and metal.
• Sand is scattered next to the piston (so that the paper does not burn).
• Gasoline is poured into the piston and ignited.

In this way, it is possible to carry out vulcanization using practically improvised means.

Homemade vulcanizer

It is quite possible to carry out homemade vulcanization, but it is better if this work is done by professionals at a service station. This procedure does not take much time and is inexpensive.

Electrical vulcanization of rubber

In general, vulcanization can be cold or hot. The electrical vulcanization process is a hot method. An electric stove with a ceramic heater is used as a heater at home; a hair dryer or a regular iron is also suitable. The optimal temperature for this method is 145C o. To determine the temperature, you can also use available means, for example, if a sheet of paper begins to char, it means that the temperature has reached the required values.

Electrical vulcanization of rubber

There are also special clamps with a heating element. Such devices can operate from a 220V household network, from a car battery, through a cigarette lighter socket, or from their own battery. It all depends on the performance of each device. These clamps are easy to use; you need to attach a rubber patch to the camera, clamp it and plug it into the network.

Material properties

The performance properties of the resulting vulcanized rubber and products made from it largely depend on the type of reagent used. Such characteristics include resistance to exposure to aggressive environments, rate of deformation during compression or increased temperature, and resistance to thermal-oxidative reactions.

The resulting bonds irreversibly limit the mobility of molecules under mechanical action, while simultaneously maintaining the high elasticity of the material with the ability to undergo plastic deformation. The structure and number of these bonds is determined by the rubber vulcanization method and the chemical agents used for it.

The process does not proceed monotonously, and individual indicators of the vulcanized mixture in their changes reach their minimum and maximum at different times. The most suitable ratio of the physical and mechanical characteristics of the resulting elastomer is called the optimum.

The vulcanizing composition, in addition to rubber and chemical agents, includes a number of additional substances that contribute to the production of rubber with specified performance properties. According to their purpose, they are divided into accelerators (activators), fillers, softeners (plasticizers) and antioxidants (antioxidants). Accelerators (most often zinc oxide) facilitate the chemical interaction of all ingredients of the rubber mixture, help reduce the consumption of raw materials and time for its processing, and improve the properties of vulcanizers.

Fillers such as chalk, kaolin, carbon black increase the mechanical strength, wear resistance, abrasion resistance and other physical characteristics of the elastomer. By replenishing the volume of feedstock, they thereby reduce rubber consumption and reduce the cost of the resulting product. Softeners are added to improve the processability of rubber compounds, reduce their viscosity and increase the volume of fillers.

Plasticizers can also increase the dynamic endurance of elastomers and abrasion resistance. Antioxidants that stabilize the process are introduced into the mixture to prevent “aging” of the rubber. Various combinations of these substances are used in the development of special raw rubber formulations to predict and adjust the vulcanization process.

Rubber properties

The vast majority of rubbers are unsaturated, high-polymer (carbo-chain) compounds with a double chemical bond between carbon atoms in the elementary units of the macromolecule. (Some rubbers are obtained on the basis of saturated linear polymers.) The molecular weight of rubbers is estimated at 400,000-450,000. The structure of macromolecules is linear or slightly branched and consists of individual units that tend to curl up into a ball and occupy a minimum volume, but this is prevented by the forces of intermolecular interaction , so the rubber molecules are tortuous (zigzag). This form of molecules is the reason for the exceptionally high elasticity of rubber (under a small load, the molecules straighten and their conformation changes).

Rules for patching cameras

1. All punctures are cleaned with a grinding stone or sandpaper. The explanation is simple: not only does this remove dirt on the surface of the chamber, but the rough surface also has a large contact area with the patch.
2. All cuts are sanded down so that their opposite edges cannot touch after applying the patch. As you move, the edges of the cut will rub against each other, which threatens to quickly tear off the recently applied patch.
3. The patch can be of any shape, but in size it must cover the puncture or cut with an overlap of 2 cm or more.

Repair of car inner tubes using Tip Top vulcanizer:

Vulcanization of tire side cuts (+ video)

The occurrence of side cuts in tires has several reasons, including a love of extreme driving, driving on difficult roads and where there are many obstacles in the form of stones, holes, debris, etc.

It is especially dangerous when the problem arose not due to a puncture, but through a cut with a sharp object; in this case, destruction of all layers of the tire, including the cord, cannot be avoided. When repairing damage occurs late, this threatens the emergence of other more complex problems, even accidents in unpredictable scenarios. Still, the situation is not dire, and repairing side cuts of tires is possible, let’s say even more, if desired, it can be done with your own hands. Looking ahead, we will say that the method used is vulcanization of cuts.

First, let's remember the design of the tire, because this is the key to successful work and increasing the chances of a good result. So, in the rubber layer there are threads made of metal and textile, and they are called in one word - cord, which is the main element that characterizes the properties of a particular tire.

More precisely, this is the level of rigidity and the second is strength, especially where the rubber touches the road when driving. Of course, you can always turn to specialists for help or a mobile tire service, and leave a certain amount there, but as an option, there is a chance to figure out the problem yourself. The above parameters directly affect the stability of the car and the level of controllability, so this is a serious matter.

Repairs can only be made when the size of the cut allows it, in the case of a longitudinal cut it is 35 mm, with a transverse cut it is 25 mm. In the area of ​​the cut we grind down the edges, as a result it should turn out to be in the form of a bowl.

After this, we thoroughly clean the work area and degrease it in order to place the raw rubber compound there. Of course, vulcanization of tire side cuts is carried out using special equipment, namely a vulcanizer, a special hair dryer or a camera, so it’s worth stocking up on one of the options.

When vulcanization is completed, the patch is glued with special glue from the inside of the tire, pressed down well and left in this condition for up to 48 hours. At the end, the vulcanization site is thoroughly cleaned, and, of course, the wheel is balanced.

Do-it-yourself hot vulcanization technology for tires

This technology is used a little longer than cold technology. At a time when there were not so many tire shops around, car and bicycle enthusiasts repaired their vehicles in the garage using exactly this method, which uses an electric or gasoline vulcanizer, which can be easily assembled with your own hands. The technology here is as follows: the master burns gasoline, which warms up the rubber using a piston. As soon as the temperature rises to 90 degrees, the raw rubber for vulcanization begins to strengthen; if you raise the temperature to 147 degrees, the process goes noticeably faster and with better quality. But it’s better not to raise it above 150, because... the material begins to deteriorate and loses its properties. After 160 degrees, raw rubber begins to char. The ideal warm-up time for hot vulcanization of raw rubber is about 8-10 minutes. A fragment of material is applied to the puncture site on the camera and compressed using a clamp so that during the chemical reaction bubbles do not form and air does not collect, forming dangerous voids.

In field conditions, it is much more difficult to carry out such an operation for cameras, but it is still possible: if there is a piece of raw rubber, you can heat it over a fire. You can determine the temperature of the flame by looking at a piece of sugar or a piece of paper: both begin to melt/char at a temperature of 145 degrees – exactly what is required for vulcanization. You can use a flat heavy stone, a wooden log or any other suitable object as a clamp.

The entire operation will take you about 20 minutes. Do not forget that the area where the inner tube patch is glued must be cleaned with sandpaper or at least wiped with gasoline to remove dirt from the tire.

Cold vulcanization

Nowadays, using this method is not difficult, since you can purchase a repair kit in every auto or bicycle parts store. The contents of this set may vary, but each one contains patches and special glue.

Cold vulcanization of rubber

The repair procedure in this case is similar to the hot method. You also need to treat the damaged surface with an abrasive, remove rubber dust and degrease. After drying, apply glue to the camera and glue the patch. In this case, it is not the duration of the pressure that plays a role, but its strength. Therefore, it will not be enough to simply press down with a stone; more force is required.

Do-it-yourself cold vulcanization of rubber is a fairly simple process that can be performed wherever you are if you have a special kit. However, raw rubber is not made with your own hands at home. For such work you need special equipment.

Hot vulcanization

An older and well-known method of repairing rubber is hot vulcanization. In past times, when there were no tire repair shops on every corner and absolutely all wheels had tubes, all car and bicycle drivers repaired tires in their garage using a homemade gasoline or electric vulcanizer.

The old electric vulcanizer has a tubular electric heater (TEH) with three contacts: one for connection to 6 volts, the second for power supply from 12 volts, and the third is common.

Squeezing with a clamp is mandatory, because if you do not press, the gas bubbles released during the heating process can create voids in the patch.

A homemade vulcanizer made from an old piston heats the rubber by burning gasoline. To limit the temperature, a sheet of paper is placed between the piston and a piece of rubber. In practice, the temperature can also be monitored using granulated sugar. Sugar begins to melt at 145 degrees, approximately at the same temperature paper chars.

Strengthening of raw rubber begins at a temperature of approximately 90 degrees and occurs optimally and quickly at 147 degrees. Above 150 degrees, rubber molecules begin to break down, forming rapidly oxidizing low molecular weight unsaturated hydrocarbons. The 160 mark is critical for rubber, as the material begins to char.

Due to the increased destructive oxidation of rubber at high temperatures, it is impossible to keep the chamber in the vulcanizer for a long time, even at the optimal 147 degrees. Typically, heating a thin patch for 8–10 minutes is sufficient.

Stationary floor vulcanizer for industrial applications

Using traditional hot vulcanization, you can patch a tube or tire 40% more efficiently, but you need to spend at least 20 minutes on this along with preparatory operations.

In addition, you will have to carry a bulky heating device with you.

1. First, you should make a patch from a piece of raw rubber. There is no need to soak the patch in gasoline if it is clean. It is not at all necessary to wash the damaged camera with gasoline or solvent, since all contaminants are completely removed with sandpaper when treating the damaged area.
2. Secondly, you need to spend time preparing to apply the patch - clean the damaged area with sandpaper.
3. Thirdly, it takes time to carry out the hottest vulcanization.

The average vulcanization rate at a temperature of 147 degrees is 1 mm of raw rubber thickness for every 4 minutes. Therefore, to warm up a regular patch with a thickness of 2 mm, it will take at least 8 minutes, and this does not take into account the time for heating the vulcanizer to operating temperature.

Many people use glue during hot vulcanization, although a piece of raw rubber is tightly welded to the chamber without it. It is also not at all necessary to cut out additional gasket from the old chamber to apply over the patch. When heated, the raw patch itself becomes normal hard rubber. This extra padding is only useful for smoothing and strengthening if a thin piece of raw rubber is used.

Vulcanizer for tire repair and how it works

To repair tires and pneumatic tubes, special devices are used - vulcanizers. This equipment works on the principle of connecting rubber parts under pressure when exposed to high temperatures. Let's find out how a tire repair vulcanizer works.

Repairing rubber using vulcanization principles is not modern technology. She has been known for a very long time. Temperature changes the molecular structure of the two rubber surfaces being joined. The layers of rubber are mixed, and as a result a strong compound is formed, which in terms of characteristics is practically no different from the monolithic composition.

Operating principle

A special piece of raw rubber is placed on the surface to be repaired. These patches are sold in hardware stores. They are also available at tire service stations. Synthetic rubber is used as raw rubber. The heating elements of the vulcanizer are connected to the connection point on each side. Next, these elements, by means of a drive, press on the joint.

Then the surface heats up. As a result of exposure to high temperatures, a strong, elastic and reliable connection is formed. After the tube or tire is repaired, it is left to cool.

Manual mechanism

The most primitive in terms of functionality is a manual vulcanizer for tire repair. In appearance and principle of operation, it resembles a clamp. But, unlike it, heating elements are used instead of sponges. This device is suitable for repairing minor damage to passenger car inner tubes. The device is called manual because the pressure force is created manually using screw clamps.

The device is connected to the car battery or standard power supply.

Portable models

There are also mobile vulcanizers. They are used to solve more complex problems. Vulcanizers can help repair even fairly serious damage to car inner tubes. Devices in this group are distinguished by a separate standard power supply. As for applying force to the pressure, then, as in the case of a manual vulcanizer for tire repair, here this too will have to be done manually (the design includes a screw clamp).

Tabletop models

A desktop vulcanizer is a more powerful, reliable and technologically advanced equipment. If manual and portable models are intended only for restoration and minor repairs of car inner tubes, then with the help of this unit you can also repair tires.

The process of creating pressure in the repair area occurs using a screw mechanism or using a drive. The latter can be pneumatic or electro-pneumatic.

Floor equipment

This tire repair vulcanizer also allows you to repair tires and tubes. Pressure is created only by a drive - pneumatic or electro-pneumatic. Such models are distinguished by the presence of a number of additional functions. Thanks to the great functionality, working on these devices is greatly simplified.

If all other devices are designed for repairing inner tubes and tires of passenger cars, then floor units can be used as vulcanizers for repairing truck tires. This equipment will be located at specialized tire service stations. For the most part, this is professional equipment that is included in the set of a special stand for repairing and balancing tires.

Additional features

The vulcanizer for restoring tires and tubes can be equipped with additional options, systems and components. Thus, one of the most popular functions is temperature control of heating elements. Due to the presence of temperature sensors, overheating of the connection point is completely eliminated. If the rubber is overheated, the quality of the connection will be significantly impaired.

If the rubber is overheated, then elasticity and strength are lost at the junction. This is a serious risk - a tire or tube may rupture while the car is moving. Overheating can cause a serious accident.

Professional vulcanizers for tire repair are equipped with a timer. The operator can control the time the repair process takes. This provides a lot of important advantages. So, first of all, the task of the operator himself is simplified. The automatic control system will stop heating the connection after a certain time.

Some devices are equipped with flexible heaters. They allow the rubber elements to be connected to be heated more evenly and the pressure to be distributed as much as possible over the surface. Considering that very often tire service stations are faced with difficult surfaces, a flexible heater is a huge advantage.

A vulcanizer for repairing truck tires must be equipped with a drive. If we compare pneumatic and electro-pneumatic with mechanical, then the first two are able to provide a more uniform force on the surfaces being connected. The more uniform the pressure, the higher the quality of the connection.

How to make a vulcanizer for tire repair with your own hands

The peculiarity is that it does not need electricity. It requires some gasoline to operate. For assembly you need a base, holes for bolts and screws, nuts, the piston itself, a beam, metal bolts with a diameter of twelve millimeters.

A wooden piece is suitable as a base. The wood will not interfere with the thorough heating of the camera and patch. The bolts are inserted into the holes and secured with self-tapping screws to prevent them from turning. M12 bolts have washers on the other side. A beam is placed on the threaded part - it will press the piston to the connection point. Next, the damage site and the patch are compressed between the base and the beam. A piston is installed on top. They pour gasoline into the latter and put rags in it and set it all on fire. After combustion and cooling, the repair can be considered complete.

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Raw rubber

This process involves all the substances that got into the rubber during vulcanization.

The only small minus, which does not cause any negative emotions, is that after cooking and subsequent cooling our bait becomes a little sticky. But this problem can be easily treated with liquid silicone grease, which is easy to buy at any auto parts store. And don't worry if the silicone lube has some odor at first. After a couple of hours, it will completely disappear, and our “jelly beans” are back in action!

And now the correct technical ones. Pick up any metal container that you wouldn’t mind using for resuscitation needs. I have this old metal bowl. I don’t cook a lot of rubber at once, so this small container is more than enough for me. And the water boils very much. Removing moisture. I use a piece of fabric as a dryer. The most important property of this fabric is that it should absorb moisture well, but not produce flying lint. Don’t forget that our soft bait has become a little sticky and the fluff from the low-quality material sticks to it very well.

Thirdly, a ziplock bag of the appropriate size. They are also sometimes called grippers. This can be either an ordinary bag that we often use in everyday life, or a “native” bag from some branded rubber. The main task of such a bag is to completely prevent air from getting inside.

So when choosing a container, pay special attention to the “lock”. Often the “locks” have some flaws and are not tight. So, we select a bag to match the tire size

I recommend that you try to start experimenting with attractants on three identical twisters of one. We cut out the mica of a suitable size so that our baits can be placed on it and the mica can easily fit in. First, lightly lubricate the mica with the attractant where our baits will lie. This is necessary so that the baits lie well and evenly on the surface. We take out the rubber and quickly place it on a cloth for removal. After laying, we spray the baits with an attractant. We put the mica baits into the bag.

There are more and more tire shops. However, on the road, both a cyclist and a motorist, a situation may arise when a tire breaks and the workshop is far away. A car enthusiast often has a spare wheel, but a bicycle driver does not have such a wheel, and it becomes necessary to vulcanize the inner tube on the road.

Cold gluing

It is good glue that can glue rubber together in the same way as hot vulcanization would. But it is worth noting that this method is a temporary repair. You can do it yourself if it breaks down on the road and then drive to the nearest service station. And then perform hot gluing. If such a situation occurs on the way, then you need to perform the following manipulations:

• Remove the wheel and inspect the damage.
• Clean and degrease the gluing area
• Apply glue to the patch and damaged area.
• Press the patch onto the rubber and hold it there for a while.
• Inflate the tire and go to the service station.

Damages of no more than 35 mm (longitudinal) and 25 mm (transverse) can also be effectively bonded. Cold vulcanization takes about 30 minutes to set. After that you can only go. But here it all depends on the size of the cut, cold or heat, as well as the quality of the glue. Complete drying of the material occurs after two days. This method is very suitable for eliminating small cuts and punctures.

Vulcanization process

The rubber vulcanization process can be divided into cold and hot. The first one can be divided into two types. The first involves the use of sulfur semichloride. The mechanism of vulcanization using this substance looks like this. A workpiece made of natural rubber is placed in the vapor of this substance (S2Cl2) or in its solution, made on the basis of some solvent. The solvent must meet two requirements:

1. It should not react with sulfur semichloride.
2. It should dissolve the rubber.

As a rule, carbon disulfide, gasoline and a number of others can be used as a solvent. The presence of sulfur semichloride in the liquid prevents the rubber from dissolving. The essence of this process is to saturate the rubber with this chemical.

Charles Goodyear invented the process of vulcanizing rubber

The duration of the vulcanization process with the participation of S2Cl2 ultimately determines the technical characteristics of the finished product, including elasticity and strength.

The vulcanization time in a 2% solution can be several seconds or minutes. If the process takes too long, so-called over-vulcanization may occur, that is, the workpieces lose their plasticity and become very brittle. Experience suggests that with a product thickness of about one millimeter, the vulcanization operation can be carried out in a few seconds.

This vulcanization technology is the optimal solution for processing parts with a thin wall - tubes, gloves, etc. But, in this case, it is necessary to strictly observe the processing modes; otherwise, the top layer of parts can be vulcanized more than the inner layers.

At the end of the vulcanization operation, the resulting parts must be washed with either water or an alkaline solution.

There is a second method of cold vulcanization. Rubber blanks with a thin wall are placed in an atmosphere saturated with SO2. After a certain time, the workpieces are moved into a chamber where H2S (hydrogen sulfide) is pumped. The holding time of workpieces in such chambers is 15 – 25 minutes. This time is sufficient to complete vulcanization. This technology is successfully used for processing glued seams, which gives them high strength.

Special rubbers are processed using synthetic resins; vulcanization using them is no different from that described above.

A little history of vulcanization

The discovery of vulcanization, oddly enough, is not associated with intense research work, but with banal negligence of work. One of the employees of the Massachusetts Rubber Factory accidentally dropped a lump of rubber mixed with sulfur onto a hot stove. The rubber was charred, but did not melt. This happened in 1839, the worker’s name was Charles Goodyear, and therefore the development of vulcanization dates back to that time. In 1844, the first patent appeared, according to which rubber should be exposed to aqua regia and copper nitrite. The process gets its name from the ancient Roman god of fire, Vulcan.

The inventor found his own vulcanization mode, noting that after it the rubber becomes resistant to temperature influences

The inventor found his own vulcanization mode, noting that after it the rubber becomes resistant to temperature influences. To do this, lead and sulfur are involved in the chemical process, which are heated to the desired temperature along with the rubber. This produces elastic rubber that is immune to the effects of sunlight and cold.

In the century before last, only sulfur was used for vulcanization, but over time, many other substances began to be added to it, for example, calcium sulfide, sulfur alkalis, arsenic sulfide, lead, antimony, zinc salts, sulfur chloride and many other substances with a high sulfur content. Vulcanization became the impetus for the industrial production of tires. The latest solution to the dough is associated with the activities of the Englishman Robert Thomson, who invented “air” wheels in 1846, and the Irishman John Dunlop, who stretched a rubber tube onto a bicycle wheel.

Making a vulcanization device

Homemade vulcanizers are divided into electric and gasoline. They are made from parts that have served their useful life. Main nodes:

• fixed table;
• a heating element;
• clamp.

The simplest electric model is made from an old iron that has a working coil. This option has a regulator, which means it is more convenient than others. The working surface is the sole. It is better to remove the handle, turn the iron over, and install it on a bracket made of thick sheet. The item to be repaired is placed on top and clamped with a clamp.

For the gasoline version, it is convenient to use the engine piston. Gasoline is poured into it and set on fire. To control, place paper on the patch. It begins to turn yellow at a temperature critical for rubber.

There are times when urgent tire repair is necessary. It is possible to carry out such repairs yourself or by contacting a repair shop.

When carrying out repair work, certain rules and technologies are observed. What is the vulcanization temperature of rubber? Read on.

External surface treatment

To clean the area being repaired, pneumatic drills with a speed of no more than 5000 per minute and tungsten carbide disk cutters should be used. Cleaning of cut edges is carried out as smoothly as possible, covering fractures and areas with concentrated internal stresses. The angle of the funnel formed when processing the side of the tire must be at least 120˚. Hard-to-reach damage areas are most effectively cleaned using special small-diameter cutters.

Cosmetic repairs require cleaning an area 5-10 mm larger than the size of the funnel along its entire length. The quality of cutting is of particular importance: the edges of the cut should be 2-3 mm apart from each other. This will ensure tight contact between the raw rubber filling the outer surface and the adhesive layer of the patch, which significantly increases the strength of the bonds formed in the repair area.

Vulcanized rubber: what is it?

Vulcanization of rubber is a rather interesting procedure, since many chemical compounds act as vulcanizing agents. The main element of this structure is rubber. It is this that is converted into rubber due to the technological process of vulcanization.

This is a chemical reaction that involves the transformation of raw rubber into a vulcanization mesh by adding other chemical compounds to it. At the same time, the rubber’s hardness, elasticity, and resistance to high and low temperatures improve.

The use of substances such as rubber and sulfur in the vulcanization process is called sulfur vulcanization. It is the sulfur atoms that contribute to the formation of intermolecular cross-links. The mixture is heated to 160°. When the percentage of added sulfur does not exceed 5%, a soft vulcanizate is obtained. Tubes, tires, rubber tubes, etc. are made from it. And if more than 30% sulfur is added, hard ebonite is obtained.

Another type of vulcanization is called radiation. It is carried out by ionizing radiation, where electron flows are used, which emits radioactive cobalt.

In this way, you can obtain an elastomer that is incredibly resistant to chemical and thermal influences.

The entire vulcanization process can be divided into several stages:

• The vulcanizing composition is placed in molds.
• The molds are installed between the heated plates of the hydraulic press.
• The mixture is heated to a certain temperature.
• Non-molded products are poured into autoclaves or boilers and can also be heated.

Note! Elastomer parts are used not only for wheel vulcanization. They are used in the production of shoes, children's goods, and installation of plumbing fixtures.

Types of vulcanization

Most often, commonly used rubbers (styrene-butadiene, butadiene and natural) are vulcanized in combination with sulfur, heating the mixture to 140-160°C. This process is called sulfur vulcanization. Sulfur atoms participate in the formation of intermolecular cross-links. When up to 5% sulfur is added to a mixture with rubber, a soft vulcanizate is produced, used for the manufacture of automobile tubes, tires, rubber tubes, balls, etc.

When more than 30% of sulfur is added, a rather hard, low-elastic ebonite is obtained. Thiuram, captax, etc. are used as accelerators in this process, the completeness of which is ensured by the addition of activators consisting of metal oxides, usually zinc.

Radiation vulcanization is also possible. It is carried out through ionizing radiation, using streams of electrons emitted by radioactive cobalt. This sulfur-free process produces elastomers that are particularly resistant to chemical and thermal attack. To produce special types of rubber, organic peroxides, synthetic resins and other compounds are added under the same process parameters as in the case of adding sulfur.

On an industrial scale, the vulcanizable composition, placed in a mold, is heated at elevated pressure. To do this, the molds are placed between heated plates of a hydraulic press. When producing non-molded products, the mixture is poured into autoclaves, boilers or individual vulcanizers. Heating of rubber for vulcanization in this equipment is carried out using air, steam, heated water or high-frequency electric current.

For many years, the largest consumers of rubber products have been automotive and agricultural engineering enterprises. The degree of saturation of their products with rubber products serves as an indicator of high reliability and comfort. In addition, parts made from elastomers are often used in the production of plumbing installations, footwear, stationery and children's products.

Curing

The properties of rubbers resemble thermoplastic polymers. The presence of unsaturated bonds in rubber molecules allows, under certain conditions, to transfer it to a thermostable state. To do this, divalent sulfur (or another substance) is added at the site of the double bond, which forms in the transverse direction, as it were, “bridges” between thread-like rubber molecules, resulting in a spatial network structure inherent in rubber (vulcanizate). The process of chemical interaction of rubbers with sulfur in technology is called vulcanization

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Many rubbers are soluble in solvents; rubbers only swell in them and are more resistant to chemicals. Ezines have higher heat resistance (NK softens at a temperature of 90 ° C, rubber operates at temperatures above 100 ° C). The change in the properties of rubber is affected by the interaction of rubber with oxygen, therefore, during vulcanization, two processes occur simultaneously: structuring under the influence of a vulcanizing agent and destruction under the influence of oxidation and temperature. The predominance of one or another process affects the properties of the vulcanizate. This is especially typical for NC rubbers. For synthetic rubbers (SR), the vulcanization process is complemented by polymerization: under the influence of oxygen and temperature, intermolecular carbon bonds are formed, strengthening the thermostable structure, which increases strength.

The thermal stability of the vulcanizate depends on the nature of the bonds formed during the vulcanization process. The strongest, and therefore heat-resistant, bonds are -C-C-; the polysulfide bond has the lowest strength -C-C-C. The modern physical theory of rubber hardening explains the increase in its strength by the presence of bonding forces (adsorption and adhesion) that arise between the rubber and the filler, as well as the formation of a continuous chain-mesh structure of the filler due to the interaction between filler particles. Chemical interaction between rubber and filler is also possible.