Polyester resins - what is it? Application, features of production technology. Polyester resins: production and work with them

Unsaturated polyester resins are widely used in various sectors of the national economy. At the same time, polyester resins with a variety of properties have been developed to perform specific production tasks. Therefore, existing resins can be classified according to their properties and, accordingly, according to the field of application.

General purpose polyester resins.
With the use of such resins, structures for domestic use or structures whose elements are lightly loaded are produced. Such resins preferably do not require reinforcement and are used in their pure form, for example, for the manufacture of trays, racks, liquid containers, etc.
Elastic resins.
Compared to general purpose unsaturated polyester resins, elastic resins have lower stiffness. They are most often added to other types of resins to reduce their brittleness and ease of processing. Buttons and other decorative items are made from such resins.
Elastic polyester resins.
This type of resin is more rigid than elastic resins. They are used for the manufacture of those products that are calculated on the resistance to shock loads - parts of aircraft and automobile bodies, fencing and protective helmets.
Resins with low shrinkage.
Low shrinkage polyester resins contain thermoplastic components such as polystyrene. They can only partially dissolve in the starting material. In such resins, during the curing process, microvoids or micropores are formed, compensating for the normal shrinkage that is customary for a polymer resin. Low shrinkage resins are used for consumer electronics parts and also in the automotive industry.
Resins with special weather resistance.
First of all, such resins resist the effects of ultraviolet radiation from sunlight. They contain components that absorb ultraviolet light. Such resins are used to form ceilings and external panels, which are used to line the roofs and walls of buildings.
Chemically resistant resins.
Conventional resins do not withstand the action of alkalis well, therefore, to increase chemical resistance, components are added to the resin that provide an increased carbon content and reduce reactive bonds. Chemical equipment is made from such resins - tanks and pipelines, chemical reactors.
fire retardant resins.
Fiberglass-reinforced products made from conventional resins can burn, albeit at a low rate. By adding special components, combustibility and flammability are further reduced and resins can be used for electrical equipment and in all cases where special fire safety is required.
Unsaturated polyester resins for special applications.
By selecting components in the composition of polyester resins, it is possible to give them special properties, such as increased heat resistance, the ability to cure under UV radiation, and others.

Appearance
The original polyester resins are viscous honey-like liquids from light yellow to dark brown. With the introduction of a small amount of hardeners, polyester resins first thicken gradually turning into a gelatinous state, after which they become rubbery and finally hard, soluble and infusible. This process, called curing, takes place at normal temperature for several hours. In the solid state, polyester resins are strong, rigid materials that can be easily dyed in any color and are most often used in combination with glass fabrics (such materials are called polyester fiberglass) as structural materials for the production of a wide variety of products.

Main advantages
Cured polyester resins are excellent structural materials with high strength, hardness, wear resistance, excellent dielectric properties, high chemical resistance, and environmental safety during operation. Some of the mechanical properties of polyester resins used in combination with glass fabrics approach or even exceed those of structural steels.
The technology for manufacturing products from polyester resins is simple, safe and cheap, because polyester resins are cured at room temperature without applying pressure, without emitting volatile and other by-products with little shrinkage. Therefore, for the manufacture of products, neither complex bulky expensive equipment, nor thermal energy is required, which makes it possible to quickly master both small-tonnage and large-tonnage production of products.
To the above advantages of polyester resins, it is necessary to add their low cost, which is two times lower than the cost of epoxy resins.
It should be noted that at present the production of unsaturated polyester resins both in our country and abroad continues to increase and this trend will continue in the future.

Flaws
Of course, polyester resins have their drawbacks. Thus, styrene, often used as a solvent, is toxic and flammable. Styrene-free grades have now been developed.
Another disadvantage is flammability. Unmodified, unsaturated polyester resins burn like hardwood. This problem is solved by introducing into their composition powder fillers (antimony trioxide, chlorine- and phosphorus-containing low-molecular organic compounds, etc.) or chemical modification by introducing chlorendic, tetrachlorophthalic acids, as well as monomers: chlorostyrene, vinyl chloroacetate and other chlorine-containing compounds.

Compound
In terms of composition, unsaturated polyester resins are a multicomponent mixture of chemicals of various nature that perform certain functions. The main components of which polyester resins are composed and the functions they perform are described in the table:

№	Name	Function	Typical content in resin
	Unsaturated polyester oligomer - polyester	main polymerizing agent	65-70%
	Solvent	Reduces viscosity and copolymerizes with base material	25-30%
	Initiator	Provides resin polymerization process	1, 5-8%
	Accelerator	Provides high polymerization speed	1, 5-6%
	Inhibitor	Prevents polymerization of the resin during storage	0, 05%

Polyester, which is the main component, is a product of the polycondensation reaction of polyhydric alcohols with polybasic acids or anhydrides containing ester groups in the main chain -CO-C. The most commonly used polyhydric alcohols are ethylene glycol, diethylene glycol, propylene glycol, glycerin and dipropylene glycol. Fumaric acid, adipic acid, maleic anhydride and phthalic anhydride are used as acids and anhydrides. In the state of readiness for processing, polyester has a low molecular weight (about 2000), and in the process of molding products after the introduction of curing initiators, it turns into a polymer with a high molecular weight and a three-dimensional network structure, which causes high strength and chemical resistance of the material.
The second necessary component is the monomer - the solvent. Moreover, the solvent plays a dual role. On the one hand, it reduces the viscosity of the resin to the level required for processing, because. the polyester itself is too thick. On the other hand, the monomer-solvent is actively involved in copolymerization with polyester, providing an acceptable polymerization rate and a high depth of material cure (polyesters themselves cure very slowly). Most often, styrene is used for this purpose, which is highly soluble, very effective and cheap, but has the disadvantage of toxicity and flammability.
The component necessary for the transfer of polyester resins from a liquid to a solid state is the curing initiator - peroxide or hydroperoxide. When interacting with another necessary component - the accelerator, the initiator decomposes into free radicals, which excite the chain polymerization process, turning polyester molecules into free radicals as well. The chain reaction proceeds at high speed and with the release of a large amount of heat. The initiator is added to the resin just before molding. After the introduction of the initiator, the form must be completed within 12-24 hours, because after this time, the resin will turn into a gelatinous state.
The fourth component of unsaturated polyester resins is the curing accelerator (catalyst), which, as mentioned above, is needed for the reaction with the initiator, as a result of which free radicals are formed that initiate the polymerization process. The accelerator can be introduced into the composition of polyesters both at the stage of manufacture and directly during processing before the introduction of the initiator. The most effective accelerators for curing polyesters at room temperature are cobalt salts, in particular cobalt naphthenate and cobalt octoate, sold under the trademarks NK and OK, respectively.
The polymerization of polyester resins must not only be activated and accelerated, but sometimes also slowed down. The fact is that polyester resins, even without initiators and accelerators, can themselves form free radicals and polymerize prematurely during storage. To prevent premature polymerization, a curing inhibitor (retarder) is needed. The mechanism of its action consists in interaction with periodically occurring free radicals with the formation of inactive radicals or compounds of non-radical nature. Phenol, tricresol, quinones and some organic acids are used as inhibitors. Inhibitors are introduced into the composition of polyesters in a very small amount (of the order of 0.02-0.05%) at the manufacturing stage.
The components described above are the main ones of which polyester resins are actually composed as binders. However, in practice, when molding products into polyesters, a huge amount of additives is introduced that carry a wide variety of functions and modify the properties of the original resins. These components include powder fillers introduced to reduce the cost, reduce shrinkage, increase fire resistance; reinforcing fillers (fiberglass) used to improve mechanical properties, dyes, plasticizers, stabilizers and others.

The differences of which we will consider in this article belong to the class of thermosetting. This means that after the solidification process, they can no longer be returned to the liquid state. Both compositions have different characteristics, which determines the scope of their application. To understand the purpose of these materials, it is useful to read the overview of polyester and epoxy resins.

Epoxy resin

Epoxy refers to materials of synthetic origin. In its pure form, it is unsuitable for use, since it is not able to go into a solid state on its own. For curing, a special hardener is added to the epoxy resin in the right proportion.

For proper use, you need to know the pros and cons of epoxy. Resin of this type is valued for its strength characteristics. It is resistant to aggressive chemicals such as acids and alkalis. The advantages of epoxy include: moderate shrinkage, high wear resistance, and excellent strength. The solidification process occurs over a wide temperature range, but the recommended range in everyday life is from +18 to +25 degrees. The hot hardening method is used in the production of high-strength products that can withstand extreme loads.

This type of resin is used both in industry and at home. The scope of their use is becoming wider due to the creation of new compositions with optimized properties. By mixing different types of epoxy resins and hardeners, it is possible to obtain a final product with completely different characteristics.

Epoxy Resin Application

Epoxy type resin is primarily used as a material for bonding surfaces: wood, leather, metal and other non-porous. Such a composition is in demand in electronics, mechanical engineering and aviation. Fiberglass, which is actively used in construction, is also made from epoxy. The resin is used for waterproofing floors and walls, including external ones. Finished products made of fiberglass after grinding and additional processing are popular in decorating interiors.

Epoxy hardener

Epoxy material consists of two components, after mixing of which the polymerization process begins. The component that causes the epoxy to cure is called the hardener. Depending on the use of different resins and hardeners, completely different epoxy mixtures can be obtained.

The proportion of the hardener in the composition may be different and depends mainly on the brand of resin. The polymerization reaction of epoxy resin is irreversible, that is, it is not possible to melt an already solidified material.

It is a mistake to believe that by overestimating the amount of hardener, hardening will be faster. An effective way to speed up the process is to increase the temperature of the mixture. Increasing the operating temperature by 10 degrees allows you to speed up the process by 3 times. For these purposes, special components are commercially available. There are also epoxy mixtures that harden at low temperatures.

Incorrect selection of the amount of hardener adversely affects the quality of the finished product. First of all, its strength and resistance to chemicals are reduced. With a small amount of hardener, the consistency of the part becomes sticky, with an excess, the polymer is released on the surface of the material. The most common resin/hardener ratios are 1/2 or 1/1. Before mixing, it is recommended to read the instructions for the correct ratio of components.

polyester resin

Such a resin is formed during the processing of special purpose alcohols. The basis of the material is polyester. To speed up the hardening process, specialized solvents and inhibitors are used. Depending on the scope of the material, it may have a different structure and properties. The resulting product needs additional processing aimed at increasing protection against water and ultraviolet radiation. The additional coating also enhances the strength characteristics of the product. Polyester resin, unlike epoxy, is characterized by low mechanical properties. But at the same time, polyester is distinguished by a low price, due to which the material is more popular.

Such resins are actively used in the construction of buildings, in the automotive industry, shipbuilding and the production process of containers for chemical compositions. Polyester components, when mixed with glass, form high-strength compounds. Thanks to this, the resulting material is used in the manufacture of canopies, roofs for buildings and lighting fixtures.

Polyester resin is also part of the artificial stone. The plastic produced using this component is used in the production of window sills, shower cabins, partitions and decorative elements. Polyester resins, unlike epoxy resins, are easy to color.

The main advantages of polyester resin

Polyester resin, unlike epoxy, is more practical. After mixing with glass, the composition acquires strength characteristics that exceed those of steel. Polyester hardening does not require special conditions and temperatures. Work with it is considered less laborious, and the material itself is cheaper.

What is the difference?

When asking the question: "Which is better, polyester or epoxy?", you need to understand why and where the resin is needed. Both materials have their pros and cons, and the final choice depends on the conditions of use, as well as the type of surface to which the resin will be applied.

Epoxy has a higher cost, but it is more durable. Possessing excellent adhesive properties, it firmly connects surfaces of various structures. Epoxy resin differs from the polyester product in low shrinkage, better mechanical characteristics, and wear resistance.

At the same time, unlike polyester, epoxy needs more time to harden, which slows down the process of manufacturing parts from this material. Working with such a resin is accompanied by increased safety measures: when working with a liquid material, gloves are required, and a respirator is needed to process a solid product. The danger is not so much the resin itself, but the components used to give it a solid state. When hardening at high temperatures, there is a chance to lose the viscosity of the material, which creates additional difficulties in work.

Which resin is better, epoxy or polyester? Reviews indicate that in most cases the first is used in the form of glue, since its properties are much higher than those of a polyester-based material. In other situations, it seems more rational to use polyester resin, which, firstly, will save money, and secondly, will simplify the work.

Benefits of using polyester

Polyester does not emit toxic elements, is easy to use, and special knowledge is not required to work with it. The composition is used to cover various surfaces, followed by treatment with a strength-enhancing agent. In terms of adhesive properties, polyester is significantly inferior to epoxy, and it is irrational to use it for gluing surfaces. As a material for decorative products, it is not suitable, as it has low mechanical properties. When mixing the composition of polyester, a small amount of catalyst is used. The material hardens quickly, within 2-3 hours.

The finished part has elasticity and resistance to bending. The downside of polyester resin products is flammability. Do not apply polyester resin to an item made from epoxy. To repair an epoxy product, it is better to use it.

How to properly prepare the surface

Resin should only be applied to previously prepared surfaces. The first step is degreasing with a solvent. After removing dirt and traces of fat, the grinding process is carried out. The top layer is removed from the surface of the material using sandpaper or a special tool. Then the dust removal process is carried out. After that, you can start applying the working component.

Safety

In order not to cause harm to health when working with resins and hardeners, it is necessary to take all precautions to the maximum. Failure to follow simple rules can result in skin damage, burns or lung problems when working with epoxy or polyester resins. Safety features when working with chemicals:

Do not use containers intended for cooking.
All manipulations must be carried out in special clothing and gloves. Before carrying out work on the hands should be applied with a protective cream. Grinding of finished products is carried out in a respirator and special glasses.
If the resin comes into contact with the skin, it must be washed immediately with soap or alcohol.

Epoxy components should be handled in a well ventilated area.

The widespread use of polyester resins in various industries, including construction, leads to the question of how to work with this material. There is a certain technology for working with polyester resin. On the features of polyester resins and on the technique of working with them, we will consider further.

Polyester resin - material application

There are a huge number of industries that use polyester resin. We offer you to get acquainted with the most popular of them:

1. Construction industry.

This material is used in the manufacturing process of fiberglass, which has an additional reinforcement of fiberglass. This plastic has high mechanical characteristics, light weight, transparent texture, attractive appearance. Plastic parts are used in the manufacture of various kinds of lighting fixtures, roofs, suspended structures. In addition, even window sills, cornices, monolithic bathrooms, shower cabins are made of polyester-based plastic. In addition, this material is easily dyed and acquires the desired color and shade.

2. Shipbuilding industry.

This industry uses the most polyester resin. Most of the parts, cases, windows are interconnected with the help of polyester resins. This material is highly moisture resistant. Therefore, materials treated with polyester resin have high resistance to rot and moisture.

3. Car manufacturing - mechanical engineering.

Polyester epoxy resin is a component of bodies, various kinds

elements that are part of cars. In addition, various types of putty and primer mixtures are made from polyester resins.

4. Branch of the chemical industry.

Since polyester resin is highly resistant to aggressive compounds, it is widely used in the chemical industry. Polyester is present in the composition of pipes through which oil is pumped.

In addition, the use of polyester resins is associated with the electrical industry, mechanical engineering, woodworking industry, sporting goods, art.

Polyester resin - material characteristics

Polyester resin is a material that is made by mixing and processing polyhydric alcohols. These resins are widely used in various industries. Due to the uniqueness of their composition, polyester resins are widely used in shipbuilding. Their use allows you to get a light, but at the same time moisture-resistant coating.

In addition, among the advantages of polyester resin, we note:

minimum thermal conductivity;
maximum moisture resistance;
duration of operation;
resistance to temperature changes;
resistance to mechanical stress;
resistance to chemicals;
high reliability indicators;
versatility and a wide range of applications.

The use of vegetable oils in the polyester resin manufacturing process makes it possible to produce a material with the same properties as inorganic resins. At the same time, in some cases, indicators of durability and reliability increase.

In order to make a two-component polyester resin or rigid polyurethane foam, a substance in the form of a polyol is used. Polyester resins - the production of environmentally friendly substances, has the following advantages:

a decrease in the volume of oil refining has a positive effect on the negative impact on the environment;
the material is obtained completely safe and harmless both for humans and for the entire planet;
thus, it is possible to significantly save money, since natural materials are cheaper.

Polyester resin transparent: technology of use

In order to work safely with polyester resins, you should familiarize yourself with and follow certain rules. Fiberglass is a very common and necessary item in construction, for the manufacture of which it is enough to learn how to work with polyester resin.

To harden polyester resins, a catalyst is needed, by introducing which the interior of the resin is filled with heat. Another polymerization option is the receipt of thermal energy by the resin from an external source. This method is expensive to perform.

Most often, after purchasing the resin, it comes with instructions that indicate the amount of polymerizer that can make the resin product hard. In addition, the amount of this substance also determines the air temperature at the time it is added to the resin.

Please note that the work should be done gradually, as the resin hardens very quickly. You should start work with half a liter of material. Working with resins is a rather dangerous process, which requires a special mask and goggles. Since the catalyst adversely affects vision.

The addition of the catalyst to the resin solution is carried out gradually, and the compositions require thorough mixing. However, the ingredients should not be mixed too quickly, so as not to get too much air into them. Mix the catalyst and resin for about three minutes to obtain a homogeneous compound.

Please note that a certain time will pass until the resin hardens, if after five minutes you have not seen the result, you do not need to add a catalyst.

The presence of a catalyst in the resin will change its color from blue to pink. In this case, before curing, the resin should be applied to the product on which it is planned to be used.

Heating or raising the temperature of the resin is an indication that the resin is beginning to polymerize. To slow down the hardening of the resin, the container in which it is located is placed in a tank with a cooled liquid, such as water, or directly in a cold store, in which there is no food.

When the resin becomes like jelly, its useful life ends. The time from the moment the resin is combined with the catalyst to this period is the life of the resin. The average use time of the resin after dilution is 20 to 60 minutes, provided the resin is of good quality and properly stored after production.

If the gelatinization of the resin has already begun, and the resin has not yet been used, then the resin is definitely discarded. However, it is not necessary to dispose of the resin in a place prone to fire, as the energy that is released during the process of combining the resin with the catalyst can lead to fire.

When throwing out the working resin, it should be evenly and thinly leveled on the surface. At the same time, the work is carried out at a place where there are no combustible materials. The entire polymerization period of the resin is controlled by changing its color. Keep in mind that curing the resin too quickly will increase its shrinkage after curing. Remember that the catalyst is injected into each of the portions of polyester resins. The optimum temperature for working with the material is at least 16 degrees, and a maximum of 40 degrees of heat. In this case, the ideal range is considered to be 25-30 degrees. At the same time, the presence of direct sunlight or rain is undesirable.

After applying the resin and separating it on the surface, it should not be moved more. All further work is carried out after the resin has completely hardened. The average waiting time is one to three hours. If there is moisture near the resin areas, the waiting period will be slightly longer.

However, the complete polymerization of the resin is carried out after a few days from the moment of its application. At the same time, if fiberglass is made, then the first days, it is distinguished by a certain plasticity, it is easily bent. Therefore, if it is planned to manufacture products from polyester resins, work should be carried out within a few days from the moment the resin was applied. Polyester resin gains strength over several weeks from the moment it is applied. Therefore, the operation of items made from it should be started only after the expiration of this time.

Features of unsaturated polyester resins

The use of unsaturated polyester resins is very popular. This is primarily due to the fact that these polymers are able to harden even at room temperature. At the same time, the allocation of side effects products is absent. Thus, the process of manufacturing reinforced plastic and other similar items is greatly simplified.

The use of these resins is especially important in the case of the manufacture of cast insulation, electrical and radio devices, fiberglass coatings, etc. In addition, unsaturated polyesters are used for the manufacture of hull parts for boats and ships, in the automotive industry. To reduce labor costs in the process of processing polyester resins, it is recommended to pay attention to the quality of the resin when purchasing it. In this case, the quality of products made of polyester resins will be at the proper level.

Polyester resin artificial stone manufacturing

The sphere of use of polyester resins involves the manufacture of artificial stone from them. In this case, the resin is a link for the filler. In order to achieve a certain effect, crumb, dye or fillers are often added to the resin. For the manufacture of molded products, such as countertops made of artificial stone, a large-sized filler is first placed in a certain form. In order to fill the resulting voids, a smaller volume filler is laid. At the same time, a combination of rubber, metal, polymer, granite, limestone materials is possible. In addition to polymer resins, substances in the form of cement, gypsum, liquid glass act as a binder.

In order to independently produce a material of artificial origin in the form of marble, it is enough to use polyester resin, chips from artificial marble. In addition, you will need special dyes and fillers that will help imitate marble.

All components of the substance are mixed with each other and poured into the mold. Most often, the form is made of glass and has the shape of a rectangle. To harden this composition, an oven is used in which hot air is present.

After the composition has completely hardened, it is polished until the crumb of artificial marble is exposed. However, these methods of manufacturing artificial stone have certain disadvantages. Among them, first of all, low strength of the obtained products, low service life, low strength.

If in some way to change the technology of manufacturing a stone, it is possible to increase its strength characteristics. For the manufacture of artificial stone, tooling is used, made of polyester, epoxy and other substances. A binding translucent substance is applied to its surface, with a layer of up to two millimeters. This substance will protect the surface of the stone from destruction under the influence of the sun, temperature changes or moisture. After the translucent layer acquires the consistency of a gel, it is covered with a filler, which is based on granite and marble chips. For its manufacture, materials of both organic and inorganic origin are used. There are several options for fillers - single or multi-fraction.

After the composite material has completely hardened, it is covered with a certain color, depending on the color of the filler and crumb. The use of a substrate based on polyester resin glass mat has the following advantages:

ensuring the strength of the product;
determination of color depth;
reduction of composites in the composition;
light transmission.

The calculation of the hazard class of polyester resin is carried out in relation to its composition and depends on its quality.

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Chapter 1 Saturated Polyester Resin Properties and Applications

Saturated polyester resins can be of various compositions, high or low molecular weight, linear or branched, solid or liquid, elastic or rigid, amorphous or crystalline. This variability, combined with good resistance to light, moisture, temperature, oxygen and many other substances, is why saturated polyester resins play an important role as film formers in coatings. In addition, saturated polyester resins are used in various industries, such as the production of fiberglass, plastic products, polyurethanes, artificial stone, etc.

NPS properties and technical characteristics

Synthetic polyester resins are synthetic polymers. They historically got their name due to the fact that the initially synthesized polymers were similar in structure and properties to natural resins, such as shellac, rosin, etc. Substances that are united by the name "resins" have an amorphous structure and consist of related molecules of unequal size and different structures (homologues and isomers). Resins are good dielectrics. They are typically characterized by the absence of a specific melting point (gradual transition from a solid to a liquid state), non-volatility, solubility in organic solvents, insolubility in water, and the ability to form films upon evaporation of the solvent.

The study of saturated polyesters began in 1901 with the preparation of "glyphthal resin" consisting of glycerol and phthalic anhydride. Industrial production of these alkyd resins began in the 1920s. in USA. The further development of the production of saturated polyester resins for paints and other purposes depends significantly on the study of new types of raw materials.

Saturated polyester resins are also sometimes referred to as oil-free alkyds because they contain most of the components used in traditional alkyd resins with the exception of fatty acid radicals.

The structure of NPS used in the production of coatings can be branched or unbranched (linear). The preferred structure of the resins in this case is amorphous (to achieve better dissolution properties).

Consider the main characteristics of saturated polyester resins used in the production of coatings.

Molecular mass

Copolymers with high molecular weight (10000-30000) usually have a linear structure. They are formed from terephthalic and isophthalic acids, aliphatic dicarboxylic acids and various diols. Good solubility in common solvents is achieved by selecting the appropriate paint formulation. In some cases (varnishes for foils, printing inks, etc.), high molecular weight polyesters are used as film-forming substances that are dried by a physical method. However, the optimum properties of the paint films are obtained only when modified with structure-forming resins. Special crystalline polyesters with a high molecular weight are crushed and used as powder paints, which have recently been increasingly used not only in the coloring of finished products, but also in the coating of rolled and sheet metal.

For ordinary coatings, polyesters with Mr 1500-4000 are used. Linear polyesters with low molecular weight can have a molecular weight up to 7000; branched polyesters have a molecular weight of up to 5000. Such resins are not suitable for the production of paints, which are dried by a physical method. They should be considered as prepolymers for reaction systems with structurant resins. Prepolymer classes and applications are presented in the table.

Temperaturevitrification. The glass transition temperature Tg of polyester resins can be varied by selecting appropriate aliphatic raw materials. Tg unplasticized aromatic copolyesters is approximately 70°C, and copolyesters formed from cycloaliphatic glycols, exceeds 100°C. Aliphatic polyesters with long methylene chains between the ether groups have Tg below -100°C. For the coil-coating process, it is preferable to use resins with a transition temperature from a highly elastic state to a glassy state of more than 45°C. Resin having a transition temperature of more than 45°C has a disordered (amorphous) structure and is soluble in a large number of organic solvents.

Solubility,crystallinityAndcompatibility. The solubility of polyester is largely determined by the nature and proportion of its constituent monomers. Polyesters with an ordered structure are crystalline. Examples of highly crystallized polyesters are polyethylene glycol terephthalate and polybutylene terephthalate. Although medium or highly crystallized copolymers are insoluble in solvents, they can be used in powder coatings. Weakly crystallized copolymers dissolve, for example, in ketones and are used mainly for the preparation of multilayer adhesives.

Low molecular weight and low Tg favorably affect the compatibility of polyester resins with other film formers (acrylic, epoxy, amino resins, cellulose esters). Not all NPCs are compatible with each other. For example, polyesters derived from phthalic acid are not always compatible with other NPS.

The table summarizes the main characteristics of NPS and evaluates their advantages and disadvantages as a raw material for the production of coatings for rolled metal.

The main characteristics of saturated polyester resins used for the production of coatings for coiled metal (coil/can coating)

The technical characteristics of the produced resins (specification) should include such basic parameters as viscosity, acid number, hydroxyl number, solid content, color (according to the Gardner color scale), solvents. Additional parameters specified in the specification may be the density of the product, ignition temperature, glass transition temperature, molecular weight, content of non-volatile substances. The performance characteristics and areas of application of the product are also indicated. The specification provides the test methods/standards against which performance was determined.

Depending on the purpose of polyester resins, the acidity coefficient can be from 0 to 100 mg KOH/g, the hydroxide number - from 0 to 150 mg KOH/g.

Approximate technical characteristics of NPS produced for coil-coating can be presented as follows:

Technical characteristics of NPS

* The range of values for the most famous resins of European and Chinese production is given. The specification for each resin indicates the range of values corresponding to its characteristics (3.5-4.5 Pas, 100-120 mg KOH / g, etc.)

Depending on the technological characteristics of the metal painting line, as well as the properties of the final product that are planned to be obtained, resins are selected, on the basis of which the corresponding coatings are produced. In particular, the curing temperature, compatibility with other components of paintwork materials, resistance to influences, under which it is planned to operate the product from painted rolled metal, are taken into account.

The characteristics of the resin also determine the type of paintwork that will be obtained on its basis. These can be primers, enamels, paints intended for various stages of coil metal coating (see the chapter on the description of the coil-coating process).

Structure formation of NPS

NPS used in the production of paints and varnishes, in most cases, must be structured by mixing with structure-forming amino-, melamine-, benzoguanamine or epoxy resins. For this reason, resin formulations may include the following chemical compounds that crosslink linear polymers: amino groups, isocyanate groups, and epoxy groups. The choice of group depends on the end use of the resins.

Structure formation is also possible when using a catalyst. If it is necessary to structure at room temperature, polyisocyanate resins are used as a crosslinking agent.

Formaldehyde modified amino resins (melamine, benzoguanamine resins and polyurea) are the most important resins used for thermal curing of polyester resins containing a functional hydroxyl group. In the domestic industry, materials based on amino and polyester resins are called oligoeiraminoformaldehyde resins. The polyester/amino resin ratio is typically between 95:5 and 60:40 (for 100% polyester).

Examples of compounds containing epoxy groups are diphenylolpropane A epoxy resins (e.g. Epikote 828™, Epikote 1001™ and Epikote 1004™, manufacturer Shell), hydrogenated diphenylolpropane A epoxy compounds, aliphatic epoxy compounds, epoxidized alkyds, epoxidized oils (e.g. epoxidized linseed oil or soybean oil ), epoxidized borates, and triglycidyl isocyanurate. The carboxyl:epoxide ratio is typically between 0.85:1 and 1:0.85. Powder coatings typically use thermal curing of carboxy-functional polyester resins with epoxy resins (these mixtures are called hybrid resins).

Examples of compounds that crosslink linear polyesters containing isocyanate groups - hexamethylene diisocyanate ((HDI),

toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), tetramethylxylene diisocyanate (TMXDI), 3,4 isocyanate methyl-1methyl-cyclohexyl isocyanate (IMCI), their dimers and trimmers. The combination of polyester and polyisocyanate resins gives two-component polyurethane paints.

Catalysts (eg benzylthymethylammonium chloride or 2-methylimidazole) are used to speed up the thermal cure reaction. The catalysts for curing polyester resin are strong acids such as sulfonic acid, mono- and dialkyl acid salt of phosphoric acid, butyl phosphate and butyl maleate.

The catalyst content is typically 0.1 to 5% (depending on the resin).

Chapter 2. Polyester resins: properties, raw materials, production

Mixtures of these oligoesters and their solutions in copolymerizable monomers (styrene, methyl methacrylate, diallyl phthalate, etc.) are also commonly referred to as polyester resins. Oligoesters are obtained by polycondensation in a melt or an inert solvent: polymaleates from maleic acid HOOCCH = CHCOOH or its anhydride (sometimes mixed with other dicarboxylic acid or anhydride) and glycol; oligoetheracrylates from unsaturated monocarboxylic acid [usually acrylic CH2=CHCOOH or methacrylic CH2=C(CH3)COOH], glycol and dicarboxylic acid. In the above formulas A and A "- bivalent residues that are part of the molecules of glycol and dicarboxylic acid, respectively; X \u003d - H, - CH3 or - Cl; x \u003d 1-5; y \u003d 0-5; n \u003d 1-20 Ethylene-, diethylene-, triethylene- and 1,2-propylene glycols are most often used as glycols, sometimes (mainly in the preparation of oligoetheracrylates) glycols are partially or completely replaced by glycerol, pentaerythritol or xylitol.Adipic acid, sebacic acid are used as dicarboxylic acids , phthalic, isophthalic, terephthalic, tetrachlorophthalic, etc. Unsaturated oligoesters are viscous liquids or solids with a softening point of 30-150 ° C, a molecular weight of 300-3000, a density of 1.1-1.5 g / cm3 (20 ° C) Most of the polyester resins are used as binders for fiberglass plastics.In addition, they are widely used for the preparation of paints and varnishes, as polymer compounds for casting parts of radio and electrical equipment, for impregnation of porous metal castings in order to seal them, as well as to obtain haberdashery products, etc. Polyester resins are also used as the basis for compositions for self-leveling floors, putties and adhesives for gluing fiberglass together, as well as with asbestos-cement and wood-fiber boards, honeycomb plastics, and other materials.

Raw materials for the production of polyesters

Glycols (ethylene glycol, 1,2-propylene glycol, diethylene glycol, triethylene glycol), glycerin, bisphenols (diphenylolpropane), pentaerythritol, as well as dibasic acids (fumaric, terephthalic, adipic, sebacic) and their anhydrides (phthalic , maleic).

Ethylene glycol is a colorless, inactive liquid, bp. 197.6°C, m.p. - 12.3°С, density 1113 kg/m3. Ethylene glycol is produced industrially by hydration of ethylene oxide in the presence of sulfuric acid or by saponification of 1,2-dichloroethane. Propylene glycol is a colorless viscous liquid, bp 187.4°C, mp. - 50°С, density 1036 kg/m3. An industrial method for producing 1,2-propylene glycol is the hydration of propylene oxide.

Diethylene glycol is a colorless viscous liquid, bp 247 ° C, mp - b ° C, density 1180 kg / m3. In industry, diethylene glycol is obtained by reacting ethylene glycol with ethylene oxide or ethylene glycol with ethylene chlorohydrin:

Triethylene glycol is a colorless viscous liquid, bp 290°C, mp. - 5?С, density 1120 kg/m3. In industry, triethylene glycol is produced from ethylene glycol and ethylene oxide. All glycols are hygroscopic, miscible in any ratio with water and ethyl alcohol.

Glycerin is a syrupy, colorless, sweet-tasting liquid, bp 290 °C, mp 17.9 °C, density 1264 kg/m3. Glycerin is very hygroscopic and miscible with water and alcohols in any ratio. In industry, glycerin is obtained by splitting fats, as well as by synthesis from propylene. The synthesis of glycerol based on propylene is a more promising method, since it does not require the consumption of food raw materials.

Pentaerythritol is a colorless crystalline substance, melting point 263.5°C, density 1397 kg/m3, water solubility 7.1% at 25°C. Pentaerythritol is obtained by reacting acetaldehyde with formaldehyde in an aqueous solution in the presence of alkali.

Adipic acid - colorless crystals, mp 149-150°C, bp 265°C at 13.3 kPa; soluble in ethyl alcohol, approximately 1.5% of adipic acid dissolves in water at 15°C.

The main industrial methods for obtaining adipic acid are:

oxidation of cyclohexanol with nitric acid or oxygen in the presence of manganese salts or through its anhydride synthesized by carbonylation of tetrahydrofuran.

Sebacic acid is colorless crystals, mp 134.5°C, bp 294.5°C at 13.3 kPa, density 1027 kg/m3; it is readily soluble in alcohol, diethyl ether; approximately 0.1% of sebacic acid dissolves in water at 15°C.

In industry, sebacic acid is obtained by dry distillation of products of alkaline cleavage of castor oil, oxidation of cyclodecane with nitric acid, electrolysis of sodium salts of adipic acid monomethyl or monoethyl ester.

Fumaric acid is a colorless crystalline substance, mp 287°C (in a sealed capillary), bp 290°C, density 1635 kg/m3. It is poorly soluble in water and almost all other solvents. Obtained by boiling a 30-40% aqueous solution of maleic acid with hydrochloric acid.

Terephthalic acid (n-phthalic) - colorless crystals, mp. 425°C (in a sealed capillary). Soluble in pyridine and dimethylformamide, insoluble in water. Terephthalic acid is obtained by oxidation of ft-xylene or n-toluic acid. For the synthesis of polyesters, terephthalic acid dimethyl ester is more often used.

Dimethyl terephthalate - colorless crystals, mp. 141-142°C, density 1630 kg/m3. Soluble in diethyl ether, moderately in hot ethyl alcohol. Dimethyl terephthalate is obtained by passing hydrogen chloride into a suspension of terephthalic acid in methanol or by heating terephthalic acid with methanol in the presence of sulfuric acid.

Phthalic anhydride - colorless crystals, mp. 130.8°С, bp. 284.5°С, density 1527 kg/m3; easily sublimes. Almost insoluble in cold water, hot hydrolyzes into orthophthalic acid. Sparingly soluble in organic solvents. Phthalic anhydride is obtained by oxidation over naphthalene or xylene in the gas phase.

Maleic anhydride - colorless crystals, mp. 52.8°C, bp. 200°С:

When dissolved in water, it gives maleic acid, in alcohols - dialkyl maleinates; soluble in dioxane, acetone, ethyl acetate, chloroform.

Maleic anhydride is produced by the vapor phase oxidation of benzene or furfural.

Properties and production methods of unsaturated polyesters

First of all, the main subject of the Research are unsaturated polyesters. Among them, polyalkylene glycol maleinates and polyalkylene glycol fumarates, as well as polyether acrylates, have found wide practical application. When obtaining polyalkylene glycol maleinates and polyalkylene glycol fumarates, in order to control their properties, a part of the unsaturated acid is usually replaced by the so-called modifying acids or their anhydrides: adipic, sebacic, terephthalic, etc., phthalic, tetra-hexahydrophthalic and other anhydrides. Saturated dibasic acids (adipic, etc.) increase the impact strength of cured polyesters, and this increase is the more significant, the longer the acid chain. Aromatic acids (anhydrides) increase the heat resistance and strength of polyesters. Anhydrides of halogen-containing aromatic acids also reduce the flammability of polyesters. Often, for this purpose, tetrachlorophthalic or chlorendic anhydride is used, which is a product of the interaction of hexachlorocyclopeitadiene with maleic anhydride.

Depending on the molecular weight (500 - 3000), the NPE is liquid or solid. Commodity NPEF, the so-called polyester resins, are produced in the form of 30-40% solutions in styrene - domestic polyester resins of the PN grades - or in triethylene glycol dimethacrylate (TGM-3) - styrene-free polyester resins of the PN-609-21M grades, etc.

To initiate the copolymerization of NPEF with monomers (curing), peroxides and hydroperoxides are usually used: benzoyl, methyl ethyl ketone, and cyclohexyl peroxides, as well as isopropylbenzene hydroperoxide. To reduce the decomposition temperature of peroxides, accelerators are introduced, which are selected depending on the initiator. So, when using benzoyl peroxide, dimethylaniline is used, and, together with hydroperoxides, cobalt naphthenate (NK accelerator). The use of accelerators makes it possible to cure NPE at room temperature. Curing is accompanied by an increase in the density of NPE and their shrinkage. The initiator and the curing accelerator are introduced into the NPEF immediately before their processing. To prevent premature gelation (gelatinization), an inhibitor, hydroquinone, is used, which is added at the beginning of the polycondensation process.

When ethylene glycol reacts with maleic anhydride, polyethylene glycol maleinate is formed. The process continues until the formation of an oligomer. The resulting polyethylene glycol maleate, when copolymerized with styrene, forms a cross-linked copolymer.

copolymer polyester resin

The use of NPEF for curing instead of allyl vinyl monomers, for example, triallyl cyanurate, makes it possible to obtain more heat- and heat-resistant copolymers with reduced flammability.

Ethylene glycol, diethylene glycol, triethylene glycol and glycerin, bisphenols are used to obtain polyester acrylates (PEA); from dibasic acids - sebacic, adipic, and also phthalic anhydride. One of the most common PEA is triethylene glycol dimethacrylate TGM-3. Shrinkage during curing of polyalkylene glycol maleinates and polyalkylene glycol fumarates is up to 5%, for polyester acrylates up to 0.5%.

The technological scheme of the process for obtaining polyalkylene glycol maleinate phthalates is as follows. The reactor for the production of unsaturated polyesters is a vertical cylindrical apparatus made of stainless steel or bimetal with an elliptical bottom and a lid, equipped with a conventional frame-anchor type stirrer and a jacket. A bubbling tube is introduced into the reactor through the lid, through which nitrogen is supplied to displace air.

Glycol is loaded into the reactor and, after it is heated to 100°C, maleic and phthalic anhydrides are loaded. Sometimes a solvent is added to the reactor in an amount of 10% by weight of the main components, which forms an azeotropic mixture with water released during synthesis, which facilitates its removal. The polycondensation process is carried out at 170-200°C and a running stirrer in a stream of nitrogen. Glycol vapor is condensed in a reflux condenser and the condensate flows into the reactor, while water vapor and nitrogen are removed through a direct condenser. Water condensate is collected in a collector. The process is controlled by acid number, which by the end of polycondensation should be 20-45 mg KOH/g. Ready polyester after cooling to 70°C is poured into a mixer, where it is dissolved in styrene or TGM-3 oligomer. The resulting solution (polyester resin PN-1, the mass ratio of polyester: styrene in which is 70: 30) is filtered after cooling and poured into a container.

The technological process for obtaining polyester acrylates is basically similar to that considered, but is carried out under milder conditions (at lower temperatures), which makes it possible to avoid polymerization of PEA.

Polyester resins of grades PN-1, PN-3, PN-6, PN-609-21M and others are viscous transparent liquids of yellow, dark red or brown color. As an initiating curing system, per 100 parts (mass) of the resin are used: 3-6 parts (mass) of isopropylbenzene hydroperoxide and 8 parts (mass) of the NK accelerator for resins PN-1, PN-3 and PN-6 ; 4 hours (wt.) of isopropylbenzene hydroperoxide and 5 hours (wt.) of NK accelerator for PN-609-21M resin.

Other PEAs (MGF-9, TMHF-11) are also yellow-brown liquids, more viscous than TGM-3. PEA is used as a binder in the production of fiberglass, casting compounds, sealants, etc. Polyester resins are widely used as fiberglass binders, compounds, varnishes for furniture and radio and television cases, and for other purposes.

The use of TGM-3 for NPE curing instead of volatile and toxic styrene makes it possible to improve sanitary and hygienic working conditions, increase heat resistance and physical and mechanical properties of cured copolymers. On the basis of unsaturated polyesters, press materials are also obtained: prepregs and premixes.

Prepregs - pre-impregnated roll fillers - paper, glass and other fibers, glass fabrics and glass mats. The binders are solid unsaturated polyesters with sufficient fluidity in molten form. In particular, crystallizable polyesters such as polyethylene glycol fumarate are suitable for making prepregs. This polyester crystallizes rapidly when mixed with acrylic and vinyl monomers.

Fabrics or paper are used to produce non-flowing prepregs, and chopped fiber mats are used to produce flowable press materials. When pressing the latter, not only the binder, but also the filler has spreadability, which makes it possible to obtain products of complex configuration.

The technological process of obtaining prepregs consists in the fact that glass mat or fiberglass is unwound from a roll and sent to the gap between two impregnating rollers, where the binder melt enters.

Premixes are pre-mixed press compositions. In practice, this term refers only to filled press materials based on unsaturated polyesters. In addition to the binder, initiator and fibrous filler (fiberglass, asbestos, etc.), powdered filler (chalk, kaolin), lubricant (zinc or magnesium stearates) and, for colored materials, dyes or pigments (turquoise lacquer, scarlet lacquer, titanium dioxide, chromium oxide).

The technological process for the production of premixes consists in the fact that a polyester, an initiator and a pigment in the form of a paste are loaded into a batch mixer (for example, a two-shaft mixer), mixed, and then a lubricant is introduced. After additional mixing, powder filler is loaded, mixed again and finally chopped glass fiber or other fibrous filler is added, followed by final mixing. When using continuous mixers, the process can be carried out continuously. The finished premix is a pasty composition or granules; it can be stored no more than 3-6 months. in a dark room at a temperature not exceeding 20 ° C.

Premixes are processed into products by compression pressing at 130-150°C, pressure of 2-10 MPa and holding time of 30-60 s per 1 mm of product thickness. Compared to the conventional technology for producing products from fiberglass, the use of premixes provides the following advantages:

1) the processing of the premix into products is separated from the production of the binder, which is often (for example, for polyester resins dissolved in styrene) associated with the use of volatile toxic monomers;

2) shrinkage of premixes is much less due to the use of powdered mineral filler;

3) when premixes are pressed, the binder is not squeezed out of the fiberglass.

Premixes are superior to prepregs in terms of fluidity, but inferior to them in terms of strength properties after curing. We will look at new copolymer materials based on saturated polyester resin in Chapter 3.

Chapter 3. New copolymers based on unsaturated polyester resin PN-15

Unsaturated polyester resins are solutions of unsaturated polyesters of molecular weight 700-3000 in monomers or oligomers capable of copolymerization with these polyesters. The advantages of polyester resins are their low viscosity; the ability to cure not only at elevated, but also at room temperature; good mechanical and electrical insulating properties in the cured state; high resistance to water, acids, gasoline, oils and other media.

The disadvantage of polyester resins is their low heat resistance.

Unsaturated polyester resins are mainly used as cold and hot curing binders in the manufacture of reinforced plastics, as well as as a base for varnishes and adhesives, components for potting compounds, plastic concrete, putties, etc.

Most of the polyester resins produced in the industry contain styrene as a solvent monomer. The widespread use of styrene is due to its low cost, good compatibility with polyesters, low viscosity of polyester styrene solutions and moderate curing shrinkage, as well as high water resistance and good mechanical and electrical insulating properties of cured resins.

Allyl ethers and oligoether acrylates such as trimethylene glycol dimethacrylate are used as non-volatile crosslinking agents for unsaturated polyesters. This reduces the toxicity of resins and in some cases reduces shrinkage during curing.

Tertiary amines are effective accelerators used in combination with benzoyl peroxide; with peroxides of methyl ethyl ketone and cyclohexanone and hydroperoxides, cobalt salts of naphthenic and other acids are used.

Initiators and accelerators are injected into the resin separately, because direct mixing may result in ignition or explosion. The sequence of introduction is not essential, it is important that each subsequent component is added only after thorough mixing with the resin of the previous one.

Resins containing accelerators can be stored for a much longer period of time (up to 1 month or more) than with the addition of initiators. In the latter case, the shelf life of mixtures usually does not exceed 10 days.

The duration of gelation depends on the temperature, the composition of the resin, the initiating system, the amount of curing additives and at 20°C can be from several minutes to several hours.

A significant part of polyester resins is processed at elevated temperatures (80-160°C), and benzoyl peroxide, hyperiz or dicumyl peroxide are usually used.

In this work, unsaturated polyester resin PN-15 was used as a binder in the production of reinforced PCM. The curing of this resin is possible by a radical chain mechanism, therefore, traditionally, substances such as peroxides, which easily decompose with the formation of active free radicals, are used as initiators of its curing. The aim of the work was to develop an unconventional, affordable and economical curing system. This curing system should provide a high degree of conversion, increased heat resistance of the polyester binder in combination with an increase in the permissible shelf life of the resulting prepregs while improving the strength characteristics of the PCM obtained from these prepregs. At the same time, the problems of studying the influence of the composition and amount of the curing system, the duration of curing, the curing temperature, and the strength of the constant magnetic field on the degree of transformation and characteristics of the obtained materials were solved. Magnetic treatment was used for the first time in the production of materials based on unsaturated polyester resin. The degree of conversion X of the initial oligomeric resins into a network product insoluble in acetone, determined by the sol-gel analysis method, was chosen as the main kinetic characteristic.

To solve the tasks set, curing was carried out under the action of sources of free radicals: hydropyrite, an alcoholic solution of iodine, and an accelerator - cobalt naphthionate. Curing of resin PN-15 proceeds by competing mechanisms - radical chain and molecular. The second mechanism requires the presence of a component containing a large number of reactive functional groups. As such a component, an available starting material was chosen - anilino-phenol-formaldehyde resin SF-342 A.

When curing a polyester binder with a curing system consisting of an anilino-phenol-formaldehyde resin and an alcoholic solution of iodine, you should use a mixture consisting of a solution of SF-342A, an alcoholic solution of iodine, the mass ratio of resin PN-15, an alcoholic solution of iodine and SF resin -342A within the studied limits practically does not affect the kinetics of curing in a given temperature-time regime (Fig. 1a), while an induction period of up to 3 hours is observed. The presence of induction periods is, in principle, characteristic of radical chain processes.

When using a curing system consisting of hydropyrite and SF-342A resin for curing a polyester binder, there is also an induction period, after which a sharp increase in the degree of conversion occurs. With the optimal duration of the curing process of 3.5-4.5 h, the maximum degree of conversion of the initial resins into a network product is achieved.

In the presence of substances that decompose with the formation of active radicals, the degree of conversion is not more than 60-70%, which can be explained by the too rapid useless decomposition of initiators with the formation of unstable active radicals, which are quickly deactivated without having time to develop the kinetic curing chains, but rather stable active radicals. radicals are not formed.

Higher degrees of conversion are achieved not by the introduction of initiators and accelerators, but by using the mutual curing effect of PN-15 and SF-342A resins. Degrees of conversion up to 85% are observed during curing of mixtures of PN-15 and SF-342A resins at their mass ratio in the range of 8: 2.5 - 8: 3.0 (Fig. 1c).

Resin SF-342A differs from resin PN-15 by a higher content of reactive functional groups, the main of which are hydroxyl groups of phenolic units and amino groups of aniline units. In this case, the SF-342A resin, contained in a smaller amount, acts as a hardener in relation to the polyester resin. In an acidic environment created by phenolic units, the curing effect of SF-342A resin

In all these cases, a gradual increase in temperature is recommended, because. with faster heating, the mass foams with gaseous curing products, which is highly undesirable in the production of structural materials. Subject to the temperature-time regime shown in Figure 2, the material is monolithic.

When studying a system consisting of PN-15: hydropyrite: SF-342A (Fig. 1b), a wave-like effect of temperature on the degree of transformation of the resulting material is observed. The optimal curing temperature for this composition of the system is 120°C, further increase in the curing temperature is not advisable.

Analyzing the obtained results, we can say that the temperature regime has a different effect on the curing systems. For example, when using the curing system PN-15: alcohol solution of iodine: SF-342A (Fig. 1a), the degree of conversion of the resulting material also increases with increasing temperature, regardless of the mass ratio of the components of the curing system. A significant increase in the degree of conversion is observed at elevated temperatures (Fig. 2).

Rice.2. Influencetemperatureregimeondegreetransformationreceivedmaterial:

A) 1 - PN-15: hydropyrite: SF-342A - (9 : 1 : 3 );

2 - PN-15: 1 : SF-342A - (9 : 4 : 2 ); 3 - PN-15: SF-342A - (8 : 2

When considering a system consisting of PN-15:SF-342A, a monotonous increase in the degree of conversion with an increase in the curing temperature is observed. However, at a sufficiently high curing temperature (170°C), it has not yet been possible to achieve high degrees of conversion (90–97%), although this system is the most rational and efficient in comparison with the curing systems for the polyester binder tested in this work.

Also in the work, the influence of layered deposition of components (SNC) and magnetic treatment (MT) on the degree of transformation and characteristics of the resulting material was studied. Technical threads (nitron, capron, viscose thread) were used as fillers. With the introduction of various fibrous fillers, the degree of conversion of the obtained composite materials is reduced to 62-64%. However, with the use of SNK and MO, it rises to 87%. With an increase in the tension of the PMF (Fig. 3), the degree of transformation increases, the water absorption of the materials obtained decreases, the specific impact strength (au d) and the breaking stress during static bending (a u) increase.

X, % materialsfromtensionPMP: A - nitron; ? - capron; AND - VN (tensionHproportionalstrengthcurrentJ ).

A linear increase in the degree of transformation is observed with an increase in the strength of the external magnetic field.

The strength characteristics also increase with increasing tension due to increased adhesion between the binder and the filler. The magnetic fields used are medium and strong in intensity, and a further increase in intensity is technically inexpedient.

conclusions

1. For the first time, a binder based on PN-15 and SF-342A was synthesized and the characteristics of reinforced PCM with these binders were determined. New methods for the production of PCMs have been applied, which make it possible to increase the degree of conversion. To increase the achieved degrees of transformation, further refinement of the composition of the curing system and the temperature-time regime of curing is required.2. For the first time, the properties of reinforced PCMs based on a new binder were controlled using magnetic treatment. The use of modification methods used earlier in this work does not give a high degree of conversion; nevertheless, the use of SNC and MO has a positive effect on the characteristics of materials based on a polyester binder, which makes it possible to control the properties of the resulting materials.

Literature

1. Alperin V.I., Avrasin Ya.D., Teleshov V.A. - In the book: Handbook of plastics. 2nd edition / Ed.V.M. Kataeva, V.A. Popova, B.I. Sazhin. - M.: Chemistry, 1975, S. 442-512.

2. Studentsov V.N., Cheremukhina I.V., Levkin A.N. Composite material based on unsaturated polyester resin. Information sheet, Saratov, CNTI, 2003 - No. 5.

3. Studentsov V.N., Cheremukhina I.V., Levkin A.N. // Plastic masses. - 2002. - No. 8. - P.33-35.

4. Studentsov V.N., Cheremukhina I.V., Levkin A.N., Skobeleva I.V., Yashina O.V. Reinforced polymer composites based on unsaturated ester resin PN-15/ Promising polymer composite materials. Alternative technologies. Recycling. Application. Ecology (composite-2001), July 3-5, 2001. Saratov: SGTU-S.120-122.

5. RF patent No. 2232175, 2004.

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