unsaturated polyester resins. Technical characteristics of NPS

Epichlorohydrin is filled into a stainless steel reactor using twisted steam and a stirrer and heated to 40-50°C.

Which is better to use polyester resin or epoxy resin

The mixing procedure with diferylolpropane is gradually introduced. After dissipation of diphenylolpropane and a homogeneous solution in a thin stream from the added solution of the measuring vessel with sodium hydroxide and at 60-70 ° C, a condensation process is carried out for 1.5-2 hours.

All this time she has to mix things up. After that, the heating of the device is turned off, water is filled during mixing.

After stopping stirring, the resulting resin can be leveled.

Layer separation is faster at 40-50°C. The cured aqueous layer (top) is separated and the remaining resin is washed with warm water at 40-50°C. The amount of water is determined by volume (usually two, three times).

Washing (mixing, leveling, separation of the aqueous layer) continues until the complete removal of the salt removed from the reaction.

Washing is controlled by decomposition (washing water) for the presence of chlorine and alkali.

Dry the resin in one device. To do this, the resin is heated to 40-50 ° C, the refrigerator is directly connected (with vacuum) and dried until the condensation of water in the refrigerator stops and the resin foams.

The resin is dried without vacuum at atmospheric pressure and at a temperature of about 120 °C.

The resin is dried to a clear resin sample at 20-25°C. The final resin is discharged into aluminum containers.

Depending on the molar ratio of the initial components, the final products can be liquid, viscous and solid.

Due to the fact that the washing liquid (low molecular weight) resin is much easier to produce than the viscosity (high molecular weight) is first obtained with a weight of low molecular weight resin, which is then poured with the required amount calculated by propane difenilol, and thus obtains the required high molecular weight resins.

Characteristics of epoxy resins

Epoxy resins are liquid, viscous or solid transparent thermoplastic products from light to dark brown.

They are easily soluble in aromatic solvents, ethers, acetone, but do not form a film, because they are not cured in thin layer(the film remains thermoplastic).

Epoxy resins are in the structure of polyethers having epoxy groups at the ends that are highly reactive (Fig.

When compounds containing a mobile hydrogen atom act on epoxy resins, they are able to dry to form three-dimensional insoluble and insoluble products with high physical and technical properties.

Thus, thermosetting is not only epoxy resin, but its mixtures with hardeners and catalysts.

Since epoxy resins claimed various substances: diamines (hexamethylenediamine, metaphenylenediamine, polyethylenepolyamine), carboxylic acids or their anhydrides (maleic, phthalic).

The composition of epoxy resins

Epoxy resins mixed with cured hardeners form thermoset compositions having valuable properties:

high adhesion to the surface of the material on which it hardens;
high dielectric properties;
high mechanical strength;
good chemical resistance and water resistance;
during healing, do not emit volatile products and are characterized by a low contraction (2-2.5%).

Properties of epoxy resins

high physical and technical properties epoxy resins, which separate them from many other resins, determine the structure of their molecules and, in particular, the presence of an epoxy group.

The number of epoxy groups in mass percent.
The epoxy group suggests an equivalent total weight of 43.
Epoxy number, equal to the number of gram equivalents of epoxy groups per 100 g of resin.
Epoxy equivalent by weight chewing gum, in grams, containing 1 g of epoxy equivalents.

The method for determining epoxy groups is based on the interaction of epoxy groups with hydrochloric acid and the formation of chlorohydrin.

In addition to the content of epoxy groups in the final resins, determine:

volatile content at 110°C;
chlorine content;
softening or lowering the temperature (for solid ED resins);
viscosity (for liquid resins such as ED-5 and ED-6);
solubility in acetone.

Table 1.
Some properties of epoxy resins based on diphenylolpropane.

polyester resins. General information.

Appearance
The original polyester resins are viscous honey-like liquids from light yellow to dark brown. When introduced, no a large number 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 is required, nor thermal energy, which allows you 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:

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 a monomer - a 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, produced under 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, great amount additives 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.

polyester resin

polyester resins, Unsaturated oligomers (oligos), such as polymaleins and oligoester acrylates. Mixtures of these solutions and their oligoesters copolymerizing monomers (styrene, methyl methacrylate, diyl phthalate, etc.) are also commonly referred to as polyester resins.

Production, properties and procedures for processing polyester resins

Our product range includes a wide range of polyester resins for various purposes. See the relevant sections for more information.

Resin types by application

Resins for general use
Low Styrene Resins
Resins based on DCPD
PET resins
Chemically resistant polyester resins based on isophthalic acid
Fire retardant resins
Resin for polymer concrete, artificial stone, hard surface
Special resins
Resins for the manufacture of matrices and accessories

Ashland polyester resin labeling

In order to better meet the different needs of customers, polyester resins come in a number of different modifications.

A number of polyester resins are pre-accelerated with the addition of thixotropic additives.

The following information will help you understand the labeling of polyester resins.

Marking example: M 105 TB- polyphosphate resin based on orthophthalic acid with low styrene emissions, thixotropic and pre-accelerated.

The first letter indicates the group of polyester resins

Pre-accelerated polyester resin (benzene peroxide curing)
F= Flame retardant polyester resin
G= polyester resin for general use
TO= chemical resistant polyester resin
M= low styrene polyester resin (LSE)
= polyester resin with special properties
Q= light thixotropic polyester resin

The numbers indicate the type of polyester in the polyester resin

100-299 = orthophalic-based polyester resins with a heat distortion temperature below 80 °C
300-399 = orthophalic-based polyester resins with a heat distortion temperature above 80 °C
500-599 = polyester resins on isophthalic and terephthalic substrates
700-899 = polyester resin based on special raw materials
900-999 = Developed grades of polyester resins

The last letter indicates the properties of the polyester resin

A, B, C, D= pre-accelerated polyester resin, modified gel time
E= pre-accelerated polyester resin
F= polyester resin filled and/or colored
H= high viscosity polyester resin
L= stabilized polyester resin
P= polyester resin with reduced styrene content
R= moderately strong polyester resin
= low viscosity polyester resin
T= thixotropic polyester resin
U= polyester resin for warm climates
= slightly modified polyester resin
W= white polyester resin
X= increase predefined properties
Y= fast curing resin
With= polyester resin with LP added

Using this information, you can evaluate the properties of polyester resins and anticipate ease of use depending on the purpose of the product, its size, operating conditions, cost estimates.

Resin storage

The resin has a maximum shelf life of 3 to 12 months (depending on type) from the date of manufacture at a temperature not exceeding 25°C and when stored out of direct sunlight.

Epoxy and polyester resins are thermosetting, due to this quality, they are not able to return to a liquid state after curing. Both compositions are made in liquid form, but are capable of possessing different properties.

What is epoxy resin?

Epoxy type resin is of synthetic origin, it is not used in its pure form, a special agent is added to solidify, that is, a hardener.

When combining epoxy resin with a hardener, strong and solid products are obtained. Epoxy resin is resistant to aggressive elements, they are able to dissolve when acetone enters. Cured epoxy resin products are distinguished by the fact that they do not emit toxic elements, and shrinkage is minimal.

The advantages of epoxy resin are low shrinkage, resistance to moisture and wear, and increased strength.

The solidification of the resin occurs at temperatures from -10 to +200 degrees.

Epoxy type resin can be hot cured or cold cured. With the cold method, the material is used on the farm, or in such enterprises where there is no possibility heat treatment.

Polyester resin: production and work with them

The hot method is used to manufacture high-strength products that can withstand heavy loads.

The working time for an epoxy type resin is up to one hour, since then the composition will begin to harden and become unusable.

Epoxy Resin Application

Epoxy type resin serves as a high-quality adhesive material.

It is able to bond wood, aluminum or steel, and other non-porous surfaces.

Epoxy-type resin is used to impregnate fiberglass; this material is used in the automotive and aviation industries, electronics, and in the manufacture of fiberglass for construction.

Epoxy resin can serve as a waterproofing coating for floors or walls with high humidity. Coatings are resistant to aggressive environments, so the material can be used for finishing external walls.

After solidification, a durable and hard product is obtained, which can be easily polished. Fiberglass products are made from such material, they are used in the economy, industry, and as room decor.

What is polyester resin?

The basis of this type of resin is polyester; solvents, accelerators or inhibitors are used to solidify the material.

The composition of the resin has different properties. It depends on the environment in which the material is used. Frozen surfaces are treated with special compounds that serve as protection against moisture and ultraviolet radiation. This increases the strength of the coating.

Polyester resin has low physical and mechanical properties compared to epoxy material, and also has a low cost, due to this it is actively in demand.

Polyester resin is used in construction, engineering, and chemical industry. When combining resin and glass materials, the product hardens and becomes durable. This allows you to use the tool for the manufacture of fiberglass products, that is, canopies, roofs, shower cubicles and others. Also, polyester resin is added to the composition in the manufacture of artificial stone.

The surface treated with polyester resin needs additional coating; for this, a special gelcoat agent is used.

The type of this tool is selected depending on the coverage. When using polyester resin indoors, when moisture and aggressive substances do not get on the surface, orthophthalic gelcoats are used. At high humidity, isophthalic-neopentyl or isophthalic agents are used. Gelcoats are also available with different qualities, they can be resistant to fire or chemicals.

The main advantages of polyester resin

Polyester resin, in contrast to the epoxy composition, is considered more in demand.

It also has a number of positive qualities.

The material is hard and chemical resistant.
The resin has dielectric properties and wear resistance.
When used, the material does not emit harmful elements, therefore it is safe for environment and health.

When combined with glass materials, the agent has increased strength, even exceeding steel.

No freezing required special conditions The process takes place at ordinary temperature.

Unlike epoxy, polyester resin has a low cost, so coatings are cheaper. The polyester-type resin has already started the curing reaction, so if the material is old, then it may have a solid appearance, and is unsuitable for work.

Polyester-type resin is easier to work with and the cost of the material saves on costs.

But to get a more durable surface or high-quality bonding, epoxy material is used.

Differences between polyester and epoxy resin, which is better?

Each material has a number of advantages, and the choice depends on the purpose of the product used, that is, under what conditions it will be applied, there are also many important role plays the type of surface.

Epoxy type resin has a higher cost than polyester material, but it is more durable. The adhesive property of epoxy exceeds any material in strength, this tool reliably connects various surfaces. Unlike polyester resin, the epoxy composition has less shrinkage, has high physical and mechanical properties, less moisture passes through, and is resistant to wear.

But unlike the polyester composition, epoxy hardens more slowly, which leads to a slowdown in the manufacture of various products, such as fiberglass.

Also, to work with epoxy requires experience or careful handling, further processing of the material is more difficult.

When using epoxy-type resin, it is necessary to protect hands with gloves, and respiratory organs with a respirator, so that when using hardeners, you do not get burns.

To work with polyester-type resin, special knowledge and experience are not required, the material is easy to use, does not emit toxic elements, and is notable for its low cost.

Polyester resin can be used on various surfaces, but the coating needs additional processing. special means. For bonding various materials polyester type resin is not suitable, it is better to use an epoxy mixture. Also, for the manufacture of decorative products, it is better to use epoxy resin, it has high mechanical properties and is more durable.

Much less catalyst is required to make a compound from polyester resin, which also helps to save money.

The polyester composition hardens faster than the epoxy material, within three hours, the finished product has elasticity or increased bending strength. The main disadvantage of polyester material is its combustibility, due to the content of styrene in it.

Polyester resin must not be applied on top of epoxy. If the product is made or patched with epoxy resin, then in the future it is better to use it for restoration.

A polyester-type resin, unlike an epoxy composition, can shrink significantly, it must be done immediately all the work in two hours, otherwise the material will harden.

How to properly prepare the surface for processing?

In order for the resin to adhere well, the surface must be properly treated, such actions are performed using an epoxy and polyester composition.

First, degreasing is performed, for this, various solvents or detergent compositions are used.

The surface must be free of grease or other contaminants.

After that, grinding is performed, that is, the top layer is removed, with a small area, sandpaper is used.

For large surfaces, special grinding machines are used. Dust is removed from the surface with a vacuum cleaner.

During the manufacture of fiberglass products or when re-applying the agent, the previous layer is covered with resin, which has not had time to completely harden and has a sticky surface.

Results

Polyester resin is much easier to work with, this material helps to save on costs, as it has a low cost, it quickly hardens, and does not need complex processing.

Epoxy-type resin is characterized by high strength, adhesive ability, and is used when casting individual products.

When working with it, you must be careful, further processing is more difficult. During work with such compounds, it is necessary to protect the hands and respiratory organs with special means.

General requirements
All work with resin must be carried out in a room equipped with supply and exhaust ventilation, at a temperature of 18-25ºС and a humidity of not more than 65%.

Lowering the temperature below 18ºС is unacceptable.
All materials before use must be kept in the conditions of the production room (at room temperature) for at least 2 days.
Before work, it is recommended to test on a small amount of resin.
ATTENTION! Mixing accelerator and hardener alone may cause explosion or fire!!!
It is necessary to first thoroughly mix the accelerator with the resin, and only then add the hardener!!!
Operating procedure
1.

Initially, we add the cobalt Co accelerator (6%) to the resin, it has a dark color, in the amount of 2% (20 g per 1 kg of resin), mix thoroughly until smooth.

In this state, the resin can be stored for up to 6 months, retaining its properties, but it is better to mix the resin and the accelerator before use.

2. The hardener, a transparent liquid, is added right before use (casting / spreading), in an amount of 2% (20 grams per 1 kg of resin).

Do not mix the resin too vigorously, because. a lot of air bubbles can get into it, which then will need to be expelled from the resin. Mix the resin for about two minutes to ensure that the hardener is evenly distributed (otherwise the curing will not be uniform).

Gel time, i.e. the time until the resin loses fluidity is between 7 and 60 minutes and depends on the curing system, ambient temperature (the warmer the faster), humidity.

Low humidity speeds up curing time. If the ambient temperature is below 18ºC, then the curing time may increase. Increasing the amount of accelerator and hardener can lead to foaming and overheating of the composition.
Basically, the operating range lies in the interval of 30 - 45 minutes.
Resin cures faster when in a compact volume and slower when spread over a large area in a thin layer (you can improve pot life by using shallow, wide pans or paint cuvettes instead of cylindrical containers).

Another way to prolong the pot life is to remove the resin with the catalyst introduced into the refrigerator during breaks, put the container on ice or in a bucket of cold water.

Polymerization of the resin is accompanied by heating the composition to 70ºС, changing the color of the composition.
Resin during hardening can shrink up to 1.5%. Reducing the amount of accelerator and hardener reduces shrinkage, but increases cure time. It is not recommended to make a layer thicker than 5 mm, so that cracking does not occur.
If fiberglass or glass mat is impregnated with resin, then you should not lay more than three layers at a time.

It is necessary to let the resin stand up, but so that the surface is sticky, and then continue laying the glass materials. The thickness of the final product depends on the thickness and number of layers of glass material. To impregnate 1 m² of laminate, you need an amount of resin that is 2 times the surface density of the glass mat or equal to the surface density of the fiberglass (depending on which material you use).

It should be borne in mind that the resin rises quickly enough, so you need to knead at a time only the amount of resin that you have time to work out in 7-10 minutes. It is better to knead less and then knead more than to throw away the uncured resin.

The curing of the resin takes an average of 1 - 3 hours, the complete polymerization of the resin occurs within 24 hours, this time can be reduced if the product is placed in drying chamber for 1 hour with heating up to 60ºС.
Polyester resin is NOT an adhesive and does not adhere well to almost any material other than glass.

- polyester resins general purpose obtained by esterification of propylene glycol with a mixture of phthalic and maleic anhydrides. The ratio of phthalic and maleic anhydrides can vary from 2:1 to 1:2. The resulting polyester alkyd resin is mixed with styrene in a ratio of 2:1. Resins of this type have a wide range of applications: they are used for the manufacture of pallets, boats, parts of shower racks, swimming pools and water tanks.

- elastic polyester resins instead of phthalic anhydride, linear dibasic acids (adipic or sebacic) are used. A more elastic and soft unsaturated polyester resin is formed. The diethylene or dipropylene glycols used instead of propylene glycol also impart elasticity to the resins. The addition of such polyester resins to general purpose rigid resins reduces their brittleness and makes them easier to process. This effect is used in the production of molded polyester buttons. Such resins are often used for decorative molding in the furniture industry and in the manufacture of picture frames. To do this, cellulose fillers (for example, crushed walnut shells) are introduced into elastic resins and cast into silicone rubber molds. Fine reproduction of wood carvings can be achieved by using silicon rubber molds cast directly on the original carvings.

- elastic polyester resins occupy an intermediate position between rigid general-purpose resins and elastic ones. They are used to make impact-resistant products such as balls, crash helmets, fences, automotive and aircraft parts. To obtain such resins, isophthalic acid is used instead of phthalic anhydride. The process is carried out in several stages. First, by reacting isophthalic acid with glycol, a low acid number polyester resin is obtained. Then add maleic anhydride and continue the esterification. As a result, polyester chains are obtained with a predominant arrangement of unsaturated fragments at the ends of molecules or between blocks consisting of a glycol-isophthalic polymer.

- low shrinkage polyester resins when molding fiberglass reinforced polyester, the difference in shrinkage between resin and fiberglass results in pitting on the surface of the product. The use of low shrinkage polyester resins reduces this effect, and the cast products thus obtained do not require additional sanding before painting, which is an advantage in the manufacture of automotive parts and household electrical appliances. Polyester resins with low shrinkage include thermoplastic components (polystyrene or polymethyl methacrylate), which are only partially dissolved in the original composition. During curing, accompanied by a change in the phase state of the system, the formation of microvoids occurs, compensating for the usual shrinkage of the polymer resin.

- weather resistant polyester resins, should not turn yellow when exposed to sunlight, for which UV absorbers are introduced into its composition. Styrene can be replaced by methyl methacrylate, but only partially, because methyl methacrylate does not interact well with the double bonds of fumaric acid, which is part of the polyester resin. Resins of this type are used in the manufacture of coatings, exterior panels and skylight roofs.

- chemically resistant polyester resins ester groups are easily hydrolyzed by alkalis, as a result of which the instability of polyester resins to alkalis is their fundamental disadvantage. An increase in the carbon skeleton of the original glycol leads to a decrease in the proportion of ester bonds in the resin. Thus, resins containing "bisglycol" (the reaction product of bisphenol A with propylene oxide) or hydrogenated bisphenol have a significantly lower number of ester bonds than the corresponding general purpose resin. Such resins are used in the manufacture of parts of chemical equipment - fume hoods or cabinets, housings of chemical reactors and tanks, as well as pipelines.

- flame retardant polyester resins an increase in the resistance of the resin to ignition and combustion is achieved by using halogenated dibasic acids instead of phthalic anhydride, for example, tetrafluorophthalic, tetrabromophthalic and "chlorendic". A further increase in fire resistance is achieved by introducing various flame retardants into the resin, such as phosphoric acid esters and antimony oxide. Flame retardant polyester resins are used in fume hoods, electrical components, building panels, and the hulls of some types of naval vessels.

- special purpose resins. For example, the use of triallyl isocyanurate instead of styrene significantly improves the heat resistance of resins. Specialty resins can be cured with UV radiation by incorporating photoactive agents such as benzoin or its ethers.

Epoxy resins - oligomers containing epoxy groups and capable of forming cross-linked polymers under the action of hardeners. The most common epoxy resins are the products of polycondensation of epichlorohydrin with phenols, most often with bisphenol A.

n can reach 25, but epoxy resins with less than 10 epoxy groups are most common. The higher the degree of polymerization, the thicker the resin. The lower the number on the resin, the more epoxy groups the resin contains.

Features of epoxy polymers:

ü the possibility of obtaining them in liquid and solid state,

ü absence of volatile substances during curing,

ü the ability to cure in a wide temperature range,

ü slight shrinkage,

ü non-toxic in the cured state,

ü high values of adhesive and cohesive strength,

ü Chemical resistance.

Epoxy resin was first obtained by the French chemist Kastan in 1936. Epoxy resin is obtained by polycondensation of epichlorohydrin with various organic compounds: from phenol to edible oils (epoxidation). Valuable grades of epoxy resins are obtained by catalytic oxidation of unsaturated compounds.

Resin requires a hardener. The hardener may be a polyfunctional amine or anhydride, sometimes an acid. Curing catalysts are also used. After mixing with a hardener, the epoxy resin can be cured - transferred to a solid, infusible and insoluble state. There are two types of hardeners: cold curing and hot curing. If it is polyethylenepolyamine (PEPA), then the resin will harden in a day at room temperature. Anhydride hardeners require 10 hours of time and heating to 180 °C in a heat chamber.

The ES curing reaction is exothermic. The rate at which the resin cures depends on the temperature of the mixture. The higher the temperature, the faster the reaction. Its rate doubles when the temperature rises by 10°C and vice versa. All possibilities to influence the cure rate come down to this basic rule. The polymerization time, in addition to the temperature, also depends on the ratio of the area to the mass of the resin. For example, if 100 g of a mixture of resin and hardener turns into a solid state in 15 minutes at an initial temperature of 25 ° C, then these 100 g, evenly spread over an area of 1 m2, will polymerize in more than two hours.

In order for the epoxy resin together with the hardener in the cured state to be more plastic and not break (do not crack), plasticizers must be added. They, like hardeners, are different, but all are aimed at giving plastic properties to the resin. The most commonly used plasticizer is dibutyl phthalate.

Table - Some properties of unmodified and unfilled diano epoxy resins.

Characteristic name	Meaning
Density at 20 ° C, g / cm 3	1.16÷1.25
Glass transition temperature, °C	60÷180
Thermal conductivity, W/(m×K)	0.17÷0.19
Specific heat capacity, kJ/(kg K)	0.8÷1.2
Temperature coefficient of linear expansion, ° С -1	(45÷65) 10 -6
Martens heat resistance, °С	55÷170
Water absorption in 24 hours, %	0.01÷0.1
Strength, MN / m 2 in tension	40÷90
Modulus of elasticity (with short-term stress), GN / m 2	2.5÷3.5
Impact strength, kJ / m 2	5÷25
Relative extension, %	0.5÷6
Dielectric constant at 20°C and 1 MHz	3.5÷5
Specific volume electrical resistance at 20°С, Ohm cm	10 14 ÷10 16
Dissipation tangent at 20°C and 1 MHz	0.01÷0.03
Electrical strength at 20°С, MV/m	15:35
Moisture permeability, kg / (cm s n / m 2)	2,1 10 -16
Coeff. water diffusion, cm 2 / h	10 -5 ÷10 -6

Epoxy-dian resins of grades ED-22, ED-20, ED-16, ED-10 and ED-8 used in electrical, electronic industry, aviation, shipbuilding and mechanical engineering, in construction as a component of casting and impregnating compounds, adhesives, sealants, binders for reinforced plastics. Solutions of epoxy resins grades ED-20, ED-16, E-40 and E-40R in various solvents are used for the manufacture of enamels, varnishes, fillers and as a semi-finished product for the production of other epoxy resins, casting compositions and adhesives.

Epoxy resins modified with plasticizers - resins of grades K-153, K-115, K-168, K-176, K-201, K-293, UP-5-132 and KJ-5-20 are used for impregnation, pouring, enveloping and sealing parts and as adhesives, electrical insulating potting compositions, insulating and protective coatings, binders for fiberglass. Composition grade K-02T is used for impregnation of multilayer winding products in order to cement them, increase moisture resistance and electrical insulating properties.

Modified epoxy resins of the EPOFOM brand are used at various industrial and civil facilities as anti-corrosion coatings to protect metal and concrete building structures and capacitive equipment from the effects of chemically aggressive environments (especially acids, alkalis, oil products, industrial and sewage effluents), precipitation and high humidity. . These resins are also used for waterproofing and monolithic self-leveling coatings of concrete floors, priming and applying a finishing layer. EPOFOM grade resin is used to produce casting and impregnating compositions with a high content of reinforcing fabrics and fillers, composite materials and wear-resistant coatings. EPOFOM is used as an impregnating component of a tubular material for the repair and restoration of pipelines of sewer networks, pressure networks of cold and hot water supply without their dismantling and extraction of pipes from the ground (trenchless method).

Compositions of the EZP brand are used to cover storage tanks for wine, milk and other liquid food products, and various kinds liquid fuel (gasoline, kerosene, fuel oil, etc.).

Phenol-formaldehyde resins. In 1909, Baekeland reported on the material he had received, which he called Bakelite. This phenol-formaldehyde resin was the first synthetic thermoset plastic that did not soften at high temperatures. Having carried out the condensation reaction of formaldehyde and phenol, he obtained a polymer for which he could not find a solvent.

Phenol-formaldehyde resins are polycondensation products of phenols or their homologues (cresols, xylenols) with formaldehyde. Depending on the ratio of the reactants and the nature of the catalyst, thermoplastic (novolacs) or thermosetting (resols) resins are formed. Novolac resins are predominantly linear oligomers, in the molecules of which the phenolic cores are connected by methylene bridges and contain almost no methylol groups (-CH 2 OH).

Resole resins are a mixture of linear and branched oligomers containing a large number of methylol groups capable of further transformations.

FFS features:

ü by nature - solid, viscous substances that enter the production in the form of a powder;

ü for use as a matrix, melt or dissolve in an alcohol solvent;

ü The curing mechanism of resole resins consists of 3 stages. At stage A, the resin (resol) is similar in physical properties to novolacs, because dissolves and melts, at stage B the resin (resitol) is able to soften when heated and swell in solvents, at stage C the resin (resit) does not melt and does not dissolve;

ü for curing novolac resins, a hardener is required (usually urotropine is introduced, 6-14% by weight of the resin);

ü easy to modify and modify themselves.

Phenolic resin was first used as an easy-to-mould, high-quality, impact-resistant insulator. high temperatures and electric current, and then became the main material of the Art Deco style. Practically the first commercial product obtained by pressing Bakelite is the ends of the high-voltage coil frame. Phenol-formaldehyde resin (PFR) has been produced by industry since 1912. In Russia, the production of cast resites under the name Carbolite was organized in 1912–1914.

Phenol-formaldehyde binders are cured at temperatures of 160-200°C using a significant pressure of the order of 30-40 MPa and above. The polymers obtained as a result are stable during prolonged heating up to 200°C, and for a limited time they are able to withstand the action of higher temperatures for several days at temperatures of 200-250°C, several hours at 250-500°C, several minutes at temperatures of 500- 1000°C. Decomposition begins at a temperature of about 3000°C.

The disadvantages of phenol-formaldehyde resins include their fragility and high volumetric shrinkage (15-25%) during curing, associated with the release of a large amount of volatile substances. In order to obtain a material with low porosity, it is necessary to apply high pressures during molding.

Phenol-formaldehyde resins grades SFZh-3027B, SFZh-3027V, SFZh-3027S and SFZh-3027D are intended for the production of heat-insulating products based on mineral wool, fiberglass and for other purposes. Phenol-formaldehyde resin grade SFZh-3027S is intended for the production of foam plastic grade FSP.

On the basis of FFS, a variety of plastic masses, called phenolics, are made. The composition of most of them, in addition to the binder (resin), includes other components (fillers, plasticizers, etc.). They are processed into products mainly by pressing. Press materials can be prepared on the basis of both novolac and resole resins. Depending on the filler used and the degree of grinding, all press materials are divided into four types: powder (press powder), fibrous, crumbly and layered.

The designation of press powders most often consists of the letter K, denoting the word composition, the number of the resin on the basis of which this press material is made, and the number corresponding to the filler number. All press powders according to their purpose can be divided into three large groups:

Powders for technical and household products (K-15-2, K-18-2, K-19-2, K-20-2, K-118-2, K-15-25, K-17-25, etc. etc.) are made on the basis of novolac resins. Products made of them should not be subjected to significant mechanical stress, high voltage current (more than 10 kV) and temperatures above 160°C.

Powders for electrical insulating products (K-21-22, K211-2, K-211-3, K-211-4, K-220-21, K-211-34, K-214-2, etc.) are made in most cases on the basis of resole resins. Products withstand the action of current voltage up to 20 kV at temperatures up to 200°C.

Powders for special-purpose products have increased water and heat resistance (K-18-42, K-18-53, K-214-42, etc.), increased chemical resistance (K-17-23. K-17- 36, K-17-81, K-18-81, etc.), increased impact strength (FKP-1, FKPM-10, etc.), etc.

Fibrous press materials are prepared on the basis of resole resins and fibrous filler, the use of which makes it possible to increase some mechanical properties of plastics, mainly specific impact strength.

Fibers - press materials based on filler - cotton cellulose. Currently, three types of fiberglass are produced: fiberglass, high-strength fiberglass and fiberglass cord. On the basis of asbestos and resole resin, press materials of grades K-6, K-6-B (intended for the manufacture of collectors) and K-F-3, K-F-Z-M (for brake shoes) are produced. Press materials containing glass fiber are called fiberglass. It has higher mechanical strength, water and heat resistance than other fibrous press materials.

Crumb press materials are made from resole resin and pieces (crumbs) of various fabrics, paper, wood veneer. They have increased specific impact strength.

Laminated press materials are produced in the form of large sheets, plates, pipes, rods and shaped products. Depending on the type of filler (base), sheet laminates are produced in the following types: textolite - on cotton fabric, fiberglass - on glass fabric, asbestos-textolite - on asbestos fabric, getinax - on paper, wood-laminated plastics - on wood veneer.

What is epoxy resin?

Epoxy type resin is of synthetic origin, it is not used in its pure form, a special agent is added to solidify, that is, a hardener.

The advantages of epoxy resin are low shrinkage, resistance to moisture and wear, and increased strength. The solidification of the resin occurs at temperatures from -10 to +200 degrees.

Epoxy type resin can be hot cured or cold cured. With the cold method, the material is used on the farm, or in such enterprises where there is no possibility of heat treatment. The hot method is used to manufacture high-strength products that can withstand heavy loads.

The working time for an epoxy type resin is up to one hour, since then the composition will begin to harden and become unusable.

Epoxy Resin Application

Epoxy type resin serves as a high-quality adhesive material. It is able to bond wood, aluminum or steel, and other non-porous surfaces.

Epoxy-type resin is used to impregnate fiberglass; this material is used in the automotive and aviation industries, electronics, and in the manufacture of fiberglass for construction. Epoxy resin can serve as a waterproofing coating for floors or walls with high humidity. Coatings are resistant to aggressive environments, so the material can be used for finishing external walls.

After solidification, a durable and hard product is obtained, which can be easily polished. Fiberglass products are made from such material, they are used in the economy, industry, and as room decor.

What is polyester resin?

The basis of this type of resin is polyester; solvents, accelerators or inhibitors are used to solidify the material. The composition of the resin has different properties. It depends on the environment in which the material is used. Frozen surfaces are treated with special compounds that serve as protection against moisture and ultraviolet radiation. This increases the strength of the coating.

Polyester-type resin has low physical and mechanical properties compared to epoxy material, and is also characterized by low cost, due to which it is actively in demand.

Polyester resin is used in construction, mechanical engineering, and the chemical industry. When combining resin and glass materials, the product hardens and becomes durable. This allows you to use the tool for the manufacture of fiberglass products, that is, canopies, roofs, shower cubicles and others. Also, polyester resin is added to the composition in the manufacture of artificial stone.

The surface treated with polyester resin needs additional coating; for this, a special gelcoat agent is used. The type of this tool is selected depending on the coverage. When using polyester resin indoors, when moisture and aggressive substances do not get on the surface, orthophthalic gelcoats are used. At high humidity, isophthalic-neopentyl or isophthalic agents are used. Gelcoats are also available with different qualities, they can be resistant to fire or chemicals.

The main advantages of polyester resin

Polyester resin, in contrast to the epoxy composition, is considered more in demand. It also has a number of positive qualities.

The material is hard and chemical resistant.
The resin has dielectric properties and wear resistance.
When used, the material does not emit harmful elements, therefore it is safe for the environment and health.

When combined with glass materials, the agent has increased strength, even exceeding steel. For solidification, special conditions are not required, the process takes place at normal temperature.

Polyester-type resin is easier to work with and the cost of the material saves on costs. But to get a more durable surface or high-quality bonding, epoxy material is used.

Differences between polyester and epoxy resin, which is better?

Each material has a number of advantages, and the choice depends on the purpose of the product used, that is, in what conditions it will be applied, the type of surface also plays an important role. Epoxy type resin has a higher cost than polyester material, but it is more durable. The adhesive property of epoxy exceeds any material in strength, this tool reliably connects various surfaces. Unlike polyester resin, the epoxy composition has less shrinkage, has high physical and mechanical properties, less moisture passes through, and is resistant to wear.

But unlike the polyester composition, epoxy hardens more slowly, which leads to a slowdown in the manufacture of various products, such as fiberglass. Also, to work with epoxy requires experience or careful handling, further processing of the material is more difficult.

With exothermic curing, during the temperature increase, the material is able to lose viscosity, this makes it difficult to work. Basically, epoxy-type resin is used in the form of glue, as it has high adhesive qualities, unlike polyester material. In other cases, it is better to work with polyester-type resin, this will significantly reduce costs and simplify the work. When using epoxy-type resin, it is necessary to protect hands with gloves, and respiratory organs with a respirator, so that when using hardeners, you do not get burns.

To work with polyester-type resin, special knowledge and experience are not required, the material is easy to use, does not emit toxic elements, and is notable for its low cost. Polyester resin can be used to treat various surfaces, but the coating needs additional treatment with a special tool. Polyester resin is not suitable for bonding various materials; it is better to use an epoxy mixture. Also, for the manufacture of decorative products, it is better to use epoxy resin, it has high mechanical properties and is more durable.

Much less catalyst is required to make a compound from polyester resin, which also helps to save money. The polyester composition hardens faster than the epoxy material, within three hours, the finished product has elasticity or increased bending strength. The main disadvantage of polyester material is its combustibility, due to the content of styrene in it.

Polyester resin must not be applied on top of epoxy. If the product is made or patched with epoxy resin, then in the future it is better to use it for restoration. A polyester-type resin, unlike an epoxy composition, can shrink significantly, it must be done immediately all the work in two hours, otherwise the material will harden.

How to properly prepare the surface for processing?

In order for the resin to adhere well, the surface must be properly treated, such actions are performed using an epoxy and polyester composition.

First, degreasing is performed, for this, various solvents or detergent compositions are used. The surface must be free of grease or other contaminants.

After that, grinding is performed, that is, the top layer is removed, with a small area, sandpaper is used. For large surfaces, special grinding machines are used. Dust is removed from the surface with a vacuum cleaner.

During the manufacture of fiberglass products or when re-applying the agent, the previous layer is covered with resin, which has not had time to completely harden and has a sticky surface.

Results

Polyester resin is much easier to work with, this material helps to save on costs, as it has a low cost, it quickly hardens, and does not need complex processing. Epoxy-type resin is characterized by high strength, adhesive ability, and is used when casting individual products. When working with it, you must be careful, further processing is more difficult. During work with such compounds, it is necessary to protect the hands and respiratory organs with special means.

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

Benefits of using

Unsaturated resins offer several important benefits:

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

Hardening does not require additional conditions. Even room temperature is enough. At the same time, the material does not emit any substances into the air and is environmentally friendly. The finished product is more durable, it is not afraid of direct sunlight. It is not at all difficult to work with this type of resin, it is plastic and hardens quickly enough, so it becomes possible job with small elements and large products, with complex shapes. You can buy 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 virtually unlimited. Initially, they were used in reinforcement for shipbuilding, but then they became a favorite material for manufacturers of various electronics, and gradually penetrated into the sports environment, into decorating art.

Unsaturated resin can be an excellent base for artificial stone surfaces and products. After mixing with filler natural origin it is poured into a special mold, where it solidifies, turning into a monolith. Having passed 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, durability and value for money. Polymer concrete has similar properties. Thanks to the combination of two structures, it receives unique characteristics of thermal conductivity, waterproofing. If ordinary concrete blocks quickly absorb moisture and because of this collapse when freezing, then the addition of 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, in the production of modern plumbing. Unsaturated polyesters do not deteriorate under the influence of chemical compounds, they do not burn out, are not afraid of extreme overheating, do not crack during sudden cooling, and do not deform even after prolonged use in adverse conditions. That is why the best surfboards and skiing boards contain resins, as well as elite bathtubs, high-quality shower trays, original and durable sinks.

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 areas industry, 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. High molecular weight copolymers (10000-30000) usually have 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 high molecular weight crystalline polyesters are crushed and used as powder paints, which in Lately are increasingly being used not only in coloring 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.

Classification of saturated polyester resins used for the production of coatings

Structure	Class	Medium Mr	Structure-forming substance	Application
	Linear, high molecular weight	10000-30000	Melamine, benzoguanamine resins	Coil/can coating containers, flexible packaging)
	Linear, low molecular weight	1000-7000	Melamine, blocked polyisocyanate resins	Coil/can coating (coatings for rolled metal/containers, flexible packaging)automotive and industrial paints
	Branched, low molecular weight, hydroxy-functional	1000-5000	Melamine, blocked/free polyisocyanate resins	Automotive/industrial paints, powder paints
	Branched, low molecular weight, carboxy-functional	1000-5000	triglycidyl isocyanate,epoxy, melamine resins	Powder coatings, waterborne paints
	Low molecular weight, contains acrylate groups	1000-5000	Electro-beam and UV curing	Paper/plastic coatings, printing inks

Source: Ullmann's Encyclopedia of Industrial Chemistry, Sixth Edition, 2002

glass transition temperature. 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 large numbers organic solvents.

Solubility, crystallinity and compatibility. 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)

General chemical formula
Properties	Molecular mass	1000-25000
	Glass transition temperature	-70°С ÷110 °С
	Solid state	amorphous or crystalline(T pl 100-250°C)
	Structure	linear or branched
	reaction groups	OH/UN
	Solubility in amorphous forms	esters, aromatic hydrocarbons, ketones
Advantages	A wide variety of compositionsGood balance between strength and elasticityGood adhesion to metal (highest - in high-molecular linear NPS)Good weather resistance
Flaws	Film thickness limited to approx. 30 µmIn some cases it is impossible to achieve the required degree of crosslinking in the final coating

Source: Degusa. Basic resin for coil coating

Specifications produced resins (specification) should include such basic parameters as viscosity, acid value, hydroxyl value, solids 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. Also indicated performance characteristics and scope of the product. 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

Index	Meaning*	Unit rev.
Viscosity, 23ºC	1-8	Pass
Color according to the Gardner scale	0-3	-
TV content. in-va	39-71	%
Acid number, 100%	0-12	mg KOH/g
Hydroxyl number	0-120	mg KOH/g
Density, 23 ºC	1040-1075	kg / m 3
Flash point	22-70 and up	°C
Glass transition temperature	8-70	°C

* 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 Pa.s, 100-120 mg KOH / g, etc.)

Depending on the technological characteristics metal painting lines, 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 (100% polyester).
Examples of compounds containing epoxy groups are diphenylolpropane A epoxy resins (e.g. Epikote 828™, Epikote 1001™ and Epikote 1004™ manufactured by 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 cross-link 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. Polyester resin curing catalysts 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).

Examples of Crosslinking Agents Used in the Production of Coil Coatings