Polyester resin and epoxy resin: differences, characteristics and reviews. Types of Unsaturated Polyester Resins

Polyester resins have found wide application in absolutely all areas of production, both serial and industrial, and individual, handicraft. Private craftsmen use this polymer material in their exclusive products; in factory production conditions, such high-quality, quick-drying compounds are also indispensable. Unsaturated varieties of polyesters have special properties.

Benefits of use

Unsaturated resins have several important advantages:

high reaction speed;
ease of operation;
safety for those who work with them.

No additional conditions are required for hardening. Even room temperature is enough. At the same time, the material does not release any substances into the air and is environmentally friendly. The finished product turns out to be more durable and is not afraid of direct sunlight. Working with this type of resin is not at all difficult; it is plastic and hardens quickly enough, so it becomes possible to work with small elements and large products with complex shapes. You can purchase high-quality material of this type, for example, on the page http://www.polypark.ru/catalog/polyester-resins.

Scope of application

The use of unsaturated polyesters is practically unlimited. Initially, they were used in reinforcement for shipbuilding, but then they became a favorite material among manufacturers of various electronics, and gradually penetrated into the sports environment and decorative art.

Unsaturated resin can be an excellent base for artificial stone surfaces and products. After mixing with a filler of natural origin, it is poured into a special mold, where it hardens, turning into a monolith. After going through the grinding stage, such a workpiece turns into a perfectly smooth and incredibly beautiful countertop, sink, tile, and so on. Unlike other compounds, unsaturated resin gives the product maximum strength, making it durable and economical to purchase. Polymer concrete has similar properties. Thanks to the combination of two structures, it obtains unique characteristics of thermal conductivity and waterproofing. If ordinary concrete blocks quickly absorb moisture and therefore collapse when frozen, then adding an unsaturated type of resin solves this problem completely.

Resins of this type are also resistant to most negative external influences. That is why they are actively used in the creation of sports and tourist equipment, and in the production of modern sanitary ware. Unsaturated polyesters do not deteriorate under the influence of chemical compounds, they do not fade, are not afraid of extreme overheating, do not crack during sudden cooling, and do not deform even after long-term use in unfavorable conditions. That is why the best surfboards and skating boards contain resins, as do luxury bathtubs, high-quality shower trays, and original and durable sinks.

Unsaturated polyester resins have found wide application in a variety of 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 their field of application.

General purpose polyester resins.
Using such resins, structures for domestic use or structures whose elements are lightly loaded are produced. Such resins generally do not require reinforcement and are used in their pure form, for example, for the manufacture of pallets, racks, liquid containers, etc.
Elastic resins.
Compared to general purpose unsaturated polyester resins, elastic ones have lower rigidity. They are most often added to other types of resins to reduce their brittleness and facilitate 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 designed to withstand impact loads - parts of aircraft and car bodies, fences and protective helmets.
Resins characterized by low shrinkage.
Low shrinkage polyester resins contain thermoplastic components, such as polystyrene. They can only partially dissolve in the source material. In such resins, microvoids or micropores are formed during the curing process, compensating for the normal shrinkage common to the polymer resin. Low shrinkage resins are used for consumer electronics parts as well as in the automotive industry.
Resins that are particularly resistant to atmospheric influences.
First of all, such resins resist the effects of ultraviolet radiation from sunlight. They contain components that absorb ultraviolet radiation. Such resins are used to form ceilings and external panels that cover 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 a decrease in chemically active bonds. Chemical equipment - containers and pipelines, chemical reactors - are made from such resins.
Fire-resistant 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 purposes.
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.

Polyesters are those polymers whose chains of macromolecules contain oxygen containing ether groups of the form - C - O - C - or ester groups of the form

The first type of polyesters is called polyethers, and the second type is called polyesters. In woodworking, poly- or oligoesters are used in significant quantities.

Poly- or oligoesters are divided into saturated and unsaturated.

There are no multiple double bonds in the chains of saturated poly- or oligoester molecules. Saturated polyesters are obtained by polycondensation of saturated dibasic acids (or their anhydrides) with di- or trihydric alcohols.

Saturated oligoesters obtained in the presence of vegetable oils are called alkyd resins.

A saturated oligoester based on dihydric alcohol ethylene glycol and adipic acid has the following structure:

Unsaturated polyesters are obtained by polycondensation of unsaturated (unsaturated) dibasic acids (or their anhydrides) with di- or trihydric alcohols, therefore, in the chains of molecules of the resulting oligomers or polymers there is a reactive double bond - R - CH = CH - R -.

An unsaturated polyester based on unsaturated maleic anhydride and dihydric alcohol ethylene glycol has the form:

The following polyester resins are widely used in woodworking:

· saturated alkyd oligoesters (glyphthals and pentaphthals), as well as

· unsaturated polyester maleates or polyether acrylates.

Alkyd glypthal resins are synthesized by condensation of glycerol with phthalic anhydride in the presence of fatty acids of vegetable oils in a melt at a temperature of 220-240 0 C. Oligomers of the following structure are obtained:

As a result of condensation, linear and branched thermosetting oligomers are formed, which subsequently slowly harden due to the interaction of the remaining reactive hydroxyl - OH and carboxyl groups - COOH and form network-like insoluble and infusible coatings.

External signs of glypthals. These are highly viscous, sticky, translucent substances. The color of glypthals ranges from light yellow to yellow-brown.

Basic properties. Glypthals have a molecular weight from 1500 to 5000. They dissolve in toluene, alcohol, xylene, and white spirit. Typically, glypthals are immediately dissolved in organic solvents and solutions with an oligomer (glypthal) concentration of 40-60% are obtained. The density of solutions is 900 - 1050 kg/m3.

Glyphtals are thermoset plastics and at room temperature they slowly harden or, as they usually say, “dry out.” In the absence of vegetable oils, during curing, significant shrinkage of the material is observed and, after “drying,” brittle coatings are formed.

To reduce shrinkage, accelerate curing and increase the elasticity of coatings, glyphtals are modified with vegetable oils.

Depending on the amount of added oil, the following types of glypthals are distinguished:

· Ultra-skinny GF. They contain less than 34% oil content.

· Skinny glypthals with an oil content of 34% to 45%.

· Medium GF, in which vegetable oil is from 46% to 55%.

· Fatty glypthals contain from 56% to 70%.

· And very fatty glyptals, in which oil can be more than 70%.

The operating temperature of cured coatings based on glypthals is from -- 20 0 C to + 100150 0 C.

Application of glyphthals. Glypthal resins (oligomers) are mainly used:

as the main component (base) of paints and varnishes (finishing) materials, such as varnishes, enamels, paints, primers

as a base for adhesives,

as a binder in the production of fiberglass,

for impregnation of textured and covering papers in the production of paper resin films for furniture cladding.

More than 70% of the total volume of produced alkyd polyester resins is used for the production of varnishes and enamels. After curing glypthals, coatings or adhesive joints have anti-corrosion properties, a pleasant appearance, good weather resistance and heat resistance up to 150 0 C.

In addition to oils for accelerated curing, accelerators are added to glyphtals - driers, mainly naphthenates or resinates of cobalt and manganese.

Pentaphtali (PF)

Alkyd pentaphthalic resins are produced in the same way as glypthal resins, only instead of glycerin, tetrahydric alcohol - pentaerythritol - is used. Oligomers of the following structure are obtained:

As a result of condensation, branched thermosetting oligomers are first formed, which are subsequently cured due to the interaction of the remaining reactive hydroxyl groups - OH and carboxyl groups - COOH and form network insoluble and infusible coatings. The reactivity of pentaerythritol is higher than that of glycerol, so curing of pentaphthals occurs faster and easier.

The external characteristics of pentaphthals are the same as those of glypthals.

The main properties and applications of pentaphthals are similar to those of glyphthals.

During the curing of pentaphthalic alkyd resins, brittle coatings are also obtained and shrinkage of the material is observed, therefore alkyd pentaphthalic resins are modified with oils, urea-formaldehyde oligomers, organosilicon liquids, nitrocellulose and other reagents. To speed up the “drying” of coatings, driers are also introduced into pentaphthales.

After modification, the curing rate of pentaphthals increases. Cured coatings based on pentaphthals have greater mechanical strength, service life and operating temperature limits than coatings based on glypthals.

Products protected by coatings based on alkyd resins can be used outdoors. Alkyd varnishes, enamels (for example, PF-115 enamel), primers, and putties are used to cover car bodies, subway cars, agricultural machinery, refrigerator bodies, parquet floors, window frames, furniture parts, skis, and other products.

Materials based on glyphthalic alkyd resins are marked with the letters GF, and those based on pentaphthalic resins - with the letters PF.

Polyethylene terephthalate (PET or PET)

Polyethylene terephthalate also belongs to the group of saturated polyesters.

A saturated polyester based on dihydric alcohol ethylene glycol and terephthalic acid has the following structure:

External signs of polyethylene terephthalate. Crystalline PET is a white, solid, durable, odorless substance. Amorphous PET is a transparent, colorless polymer. Heavier than water. At temperatures above 100°C, polyethylene terephthalate is hydrolyzed (destroyed) by alkali solutions, and at 200°C - even by water.

Basic properties. PET is a thermoplastic with a density of 1380 - 1400 kg/m 3 and a melting point of ~ 255 - 265 0 C. Softening temperature of ~ 245 - 248 0 C. It has high chemical resistance; in the cold it does not dissolve in water, in traditional organic solvents, or in dilute solutions of acids and alkalis. Stable in solutions of bleaching agents. It dissolves only when heated to 40 - 150 0 C in aromatic (similar in structure) hydrocarbons, such as phenol, cresol, in an alcohol-benzene mixture. Resistant to moths and microorganisms, good dielectric. Polyethylene terephthalate is characterized by high strength, resistance to abrasion and repeated deformation during stretching and bending; resistant to light, x-rays, and -rays. Operating temperature range from - 60 0 C to + 170 0 C.

Application of polyethylene terephthalate. About 80% of all PET produced is used to produce lavsan fiber. Other trade names for the fiber are terylene, dacron, tetheron, elan, tergal, tesil. The fibers do not wrinkle, have high strength, elasticity, and are resistant to light and abrasion. The properties are similar to acetate fibers. Modified fibers are easily dyed.

PET fibers are used to make technical fabrics for workwear, tarpaulins, fishing nets, ropes, fire hoses, and belts. In addition, furniture and drapery fabrics for upholstery of upholstered furniture are produced from PET fibers.

About 20% of PET produced is used to make film. The films are transparent, durable, impermeable to water vapor, oxygen, nitrogen and solvent vapors. In this regard, they are used for food packaging, for the manufacture of bottles for carbonated drinks and juices. In addition, films are used as a substrate for various tapes for audio and sound recording, in the production of film and photographic films.

Unsaturated oligo- and polyesters

Among the unsaturated polyesters, the most common are the condensation products of maleic anhydride with ethylene glycol, which are called oligoester maleates and have the following structure:

The resulting oligoester maleates contain an unsaturated bond - R - CH 2 = CH 2 - R -, which can easily cure at room temperature without releasing low molecular weight by-products.

External characteristics of oligoester maleates. These are transparent, colorless liquids of low viscosity. Transmits 92% of sunlight. Does not change the natural color of the wood.

Basic properties. Oligoestermaleinates - thermosets with a density of 1100-1500 kg/cm 3; have a molecular weight of 300 to 3000 and are highly soluble in organic solvents and monomers. Solutions of oligoethermaleinates have low viscosity, are transparent and do not change the natural color of the wood. They have good adhesion to fiberglass, paper and metals. When “drying”, i.e. curing to form a durable polymer with a network structure, minimal shrinkage of the coatings is observed.

As a rule, unsaturated oligoesters are dissolved at T = 70 0 C in a monomer (most often in styrene) and 60-75% solutions are obtained. These solutions are called NPS unsaturated polyester resins. They serve as the basis for binders in the production of fiberglass and are used for impregnation of papers and for the production of varnishes, enamels and primers.

Accelerated curing of coatings is carried out either by heating, or under the influence of ultraviolet (UV) or infrared rays (IR), or under the influence of an accelerated electron beam (ABE). Solidification (cross-linking) of molecules occurs due to the opening of double bonds in oligoester molecules and in styrene monomer molecules, as a result of which the oligoester molecules are cross-linked with “bridges” of styrene molecules.

To eliminate fragility, increase the elasticity and mechanical strength of coatings, unsaturated oligo-(poly)esters are modified with saturated acids (adipic, sebacic, phthalic). Coatings based on modified polyesters are hard, mechanically strong, have gloss, good electrical insulating properties and are resistant to water, gasoline, oils and diluted acids. The coatings are resistant to temperatures of +80 - +100 0 C.

Application of unsaturated poly- and oligoesters. They are used to produce insulation in electrical and radio engineering, cements, self-leveling floors, and fiberglass. Fiberglass is used to make car bodies, bumpers, and car tuning parts. The hulls of boats and boats are molded from fiberglass impregnated with unsaturated polyester, and damage to the bodies of cars, boats and boats is repaired. Unsaturated polyester resins are cheaper and more convenient than epoxy resins. They are less viscous, easy to apply and cure quickly under normal conditions. Unsaturated polyester resins are well compatible with various pigments, dyes, plasticizers and dry bulk fillers (chalk, talc, sand, kaolin, etc.) Decorative products are made from them by pouring into molds: fittings, figurines, buttons and other haberdashery items products, polymer concrete and artificial stone (furniture countertops, window sills, baseboards, fireplace linings, sinks, bathtubs, sinks, tiles).

Varnishes and primers based on unsaturated polyesters are conventionally designated by the letters PE, PN, NPS. Varnishes are used for finishing furniture of the highest class, for finishing television and radio equipment (for example, cold-drying varnish of the PE-265 brand).

Polyester adhesives are used to glue together asbestos-cement and wood-fiber boards, honeycomb plastics, and other materials.

The modern chemical industry produces many types of resins used in various industries and in the production of composite materials. Among this variety, epoxy and polyester thermosetting resins are most actively used.

They, unlike thermoplastics, do not return to their original (liquid) state under the influence of heat after curing. Both resins have a liquid, syrupy consistency, but each has a number of specific properties.

A synthetic oligomeric compound that is not used in its pure form, but only with a polymerizing component (), in combination with which the resin exhibits its unique qualities. The ratio of epoxy resin to hardener has wide limits.

Due to this, the final compositions are varied and used for different purposes. These are both tough and hard, resembling rubber in consistency, and materials stronger than steel. The polymerization reaction is irreversible. Cured resin does not melt or dissolve.

Application area

Epoxy materials have unlimited possibilities for use. Traditionally they are used as:

impregnating agent for glass fibers, fiberglass, gluing various surfaces;
waterproofing coating of walls and floors, including swimming pools and basements;
chemically resistant coatings for interior and exterior finishing of buildings;
products that increase strength and water resistance for wood, concrete and other materials;
raw materials for casting forms subjected to cutting and grinding in the production of fiberglass products in the electronics industry, construction, household, design work.

Advantages and disadvantages of epoxy

Polymer two-component compositions, which include a hardener and epoxy resin, have many undeniable advantages, including:

high strength of the formed joints;
minimum degree of shrinkage;
low sensitivity to moisture;
improved physical and mechanical parameters;
polymerization temperature in the range from -10 to +200 degrees Celsius.

The unlimited number of variations of created compounds and many positive characteristics have not made epoxy resins more in demand than polyester resins. This is due to the disadvantage of this polymer, such as cost. This is especially true on an industrial scale, when the amount of resin used for impregnation is large.

Why are epoxy resins needed?

This two-component compound is used quite rarely as a construction material, but there are situations in which it has proven itself to be the best. Today it is almost impossible to find a better adhesive composition than epoxy resin.

It serves as an excellent protective coating and is recommended for use when gluing various materials. These include a variety of wood species, metals such as steel and aluminum, and any non-porous surfaces. With its help, you can improve the performance qualities of fabric materials, but not in cases of working with large volumes. The latter is due to high costs.

Epoxy adhesive

A special epoxy composition with high strength adhesion to many materials, available both rigid and elastic.

If the glue is intended to be used exclusively for household needs, it is enough to purchase a composition that does not require compliance with any strict proportions. Such “kits” are sold in the form of a cold-type resin and hardener. Most often, they already come in the required ratio, which can vary from 100:40 to 100:60.

The use of this type of glue is not limited solely to household needs. The composition is actively used in a wide variety of fields, including even aircraft manufacturing. The proportions and types of hardeners are different. It all depends on what purpose the glue is used for.

Preparation of epoxy resins and glue

Mixing resin and hardener when creating an adhesive solution in small quantities does not require any special conditions. Both an overdose and a lack of polymerizing agent are acceptable. The recommended (standard) proportion is 1:10. If the resin is prepared in large quantities, for example, for pouring into a mold to make fiberglass products, then both the selection and work with components must be approached responsibly and carefully.

When purchasing resin and hardener, it is necessary to clarify their purpose. The resin, if it is necessary to prepare several kilograms of the composition, is preheated. Only after this are added polymerizing components and plasticizers. The presence of harmful vapors emitted requires the use of personal protective equipment. Failure to follow safety rules can result in burns and the development of respiratory diseases.

Epoxy resin usage time

This parameter is most important when working with compounds, since the period during which they remain viscous or liquid and are suitable for processing has its limitations. The “working time” of the composition depends on several factors that must be taken into account during the preparation of the compound.

Curing of some compounds occurs at a temperature of -10, others - above +100 degrees. As a rule, you can work with the composition from half an hour to an hour. If it hardens, it will become unusable. Therefore, when preparing compositions, you need to clearly control both the amount of hardener and the temperature of the resin.

It is a product of the petrochemical industry, the main component of which is polyester. For polymerization (hardening), components such as solvents, initiators, inhibitors, and accelerators are added to it. The composition of polyester resins may be changed by the manufacturer depending on the specific application.

Hardened surfaces are coated with a special substance (gelcoat), which increases the strength and resistance of the coating to ultraviolet radiation, moisture and water. The physical and mechanical properties of polyester resins are significantly lower than epoxy resins, but due to their low cost, they are the most popular.

Scope of use

Polyester resin is actively used in industries such as mechanical engineering, chemical industry, and construction. The resin is especially strong when combined with glass materials in the construction industry.

The combination of these two materials allows this type of resin to be used in the production of fiberglass, from which high-strength and mechanically resistant canopies, roofs, wall partitions, shower stalls and other similar products are made. This type of resin is one of the components in the production process of artificial stone, significantly reducing the cost of finished products.

Polyester Resin Coatings

Finished products made of polyester resin, given their not the highest physical and mechanical properties, need to be protected with gelcoat. The type of this special substance depends on the application of the final product.

Products that are not exposed to an active chemical environment or water and are used indoors are covered with orthophthalic gelcoats, and in conditions of high humidity or difficult climates, for example, in shipbuilding, swimming pools, baths - isophthelic-neopentyl and isophthalic. There are special-purpose gelcoats that can be fire-resistant or have increased resistance to chemical compounds.

Advantages of polyester

Polyester resins, unlike epoxy resins, are a more popular structural material, and in the cured state they have the following advantages:

hardness;
resistance to chemical environments;
dielectric properties;
wear resistance;
absence of harmful emissions during operation.

In combination with fiberglass fabrics, they have similar and sometimes even higher parameters than structural steel. The cheap and simple production technology inherent in these resins is due to the fact that they harden at room temperature, but at the same time they shrink slightly.

This eliminates the need for bulky heat treatment units. Considering this and the fact that polyester resins are half the price of epoxy resins, the cost of the final product is low. All this makes the use of polyester-based resins beneficial for both the manufacturer and the buyer.

Flaws

The disadvantages of polyester resins include the use of a flammable and toxic solvent such as styrene during the production process. Many manufacturers have stopped using it, so when purchasing resin, you need to pay attention to the composition.

Another disadvantage of the composition is the flammability of the resin. In its unmodified form, it burns like hardwood. To solve this problem, manufacturers introduce powder fillers with fluorine and chlorine or carry out chemical modification.

Nuances of choice

Polyester resins are supplied in a “started” polymerization reaction, that is, after a certain time they turn into a solid state. And if you purchase old resin, it will not have the declared properties and characteristics. Many manufacturers provide a guarantee of freshness for their products.

The shelf life of polyester resins is about six months. If you follow storage rules, for example, keep the composition in the refrigerator without freezing, you can use the resin throughout the year. Avoid exposure to direct sunlight and ambient temperatures above +20 degrees.

Epoxy and polyester resins

Working with polyester resins is much easier than with epoxy resins, and their cost is lower. However, when choosing a material for reliable gluing of surfaces or casting of decorative products, it is recommended to give preference to epoxy compounds.

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

Epoxy resin

Epoxy is a material of synthetic origin. In its pure form, it is unsuitable for use, since it is not capable of turning into a solid state on its own. To harden, a special hardener is added to the epoxy resin in the required proportion.

To use it correctly, you need to know the pros and cons of epoxy resin. This type of resin is valued for its strength characteristics. It is resistant to aggressive chemical compounds such as acids and alkalis. The advantages of epoxy include: moderate shrinkage, high wear resistance, and excellent strength. The hardening process occurs over a wide range of temperatures, but the recommended range in everyday life is from +18 to +25 degrees. The hot curing method is used to produce 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 thanks 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.

Application of epoxy resin

Epoxy resin is primarily used as a material for gluing surfaces: wood, leather, metal and other non-porous. This 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 fiberglass products after grinding and additional processing are popular in decorating interiors.

Hardener for epoxy resin

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

The proportion of hardener in the composition can 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 hardened material.

It is a mistake to believe that if the amount of hardener is too high, hardening will occur 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. Special components are commercially available for these purposes. There are also epoxy mixtures that harden at low temperatures.

Incorrect selection of the amount of hardener has a detrimental effect on the quality of the finished product. First of all, its strength and resistance to chemicals decreases. If there is a small amount of hardener, the consistency of the part becomes sticky; if there is 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

This 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 application of the material, it may have different structure and properties. The resulting product requires additional processing aimed at increasing protection from water and ultraviolet radiation. The additional coating also enhances the strength characteristics of the product. Polyester resin, unlike epoxy resin, is characterized by low mechanical properties. But at the same time, polyester is distinguished by its 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 in the production of containers for chemical compositions. Polyester components, when mixed with glass, form highly durable compounds. Thanks to this, the resulting material is used in the manufacture of canopies, roofs for buildings and lighting fixtures.

Polyester resin is also included in artificial stone. Plastic made 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 paint.

The main advantages of polyester resin

Polyester resin, unlike epoxy resin, is more practical. After mixing with glass, the composition acquires strength characteristics exceeding the properties of steel. Polyester does not require special conditions or temperatures to harden. Working with it is considered less labor-intensive, 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 the resin will be applied to.

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

At the same time, unlike polyester, epoxy takes longer to harden, which slows down the process of manufacturing parts from this material. Working with such a resin requires increased safety measures: when working with liquid material, gloves are required; when handling a solid product, a respirator is required. The danger is not so much the resin itself as the components used to give it a solid state. When hardening under high temperature conditions, there is a chance of losing the viscosity of the material, which creates additional difficulties in work.

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

Advantages 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 coat various surfaces followed by treatment with a strength-increasing agent. In terms of adhesive properties, polyester is significantly inferior to epoxy, and it is irrational to use it for gluing surfaces. It is not suitable as a material for decorative products, as it has low mechanical properties. When mixing the polyester composition, a small amount of catalyst is used. The material hardens quickly, within 2-3 hours.

The finished part is elastic and resistant to bending. The disadvantage of products made from polyester resin is flammability. Do not apply polyester resin to a product made of epoxy. To repair a product made from epoxy material, it is better to use the same material.

How to properly prepare the surface

The resin should only be applied to a previously prepared surface. The first step is degreasing using a solvent. After removing dirt and grease, the sanding 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 this, you can begin applying the working component.

Safety precautions

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 these simple rules can result in skin damage, burns, or lung problems when working with epoxy or polyester resins. Safety precautions when working with chemicals:

The use of containers intended for cooking is prohibited.
All manipulations must be carried out in special clothing and gloves. Before carrying out work, apply protective cream to your hands. Finished products are polished using a respirator and special glasses.
If resin comes into contact with your skin, you should immediately wash it with soap or clean it with alcohol.

Handling of epoxy components should be carried out in a well-ventilated area.