Hardener for epoxy resin - composition, varieties, application features
Epoxy resin is an oligomeric synthetic a compound that is widely used to create paints and varnishes, adhesives, beautiful and high-strength household products. The epoxy hardener helps the product to achieve its final properties by starting the curing process.
What is it for? The type of curing of epoxy resin will be very different from the same indicator for paintwork. If the primers, paints, adhesives harden only after the liquid has evaporated, then the resin can only be hardened after adding a special solution. For this reason, resin is often referred to as a two-component material.
A hardener is a chemical liquid substance, an accelerator of a chemical reaction and its full participant. After the resin and hardener are combined, polymerization begins, and as a result, the composition is solid (i.e. stable).
It is also important to add the exact ratio of the two components to the mixture.
The accuracy of the ratio of funds will determine the following properties of the final material:
Why is chemical composition so important? If you violate the proportions, the quality characteristics will decrease, as will the life of the finished material.
Correct dilution gives a thermosetting quality composition that will have the following characteristics:
Now let's look at how such substances are classified.
All hardeners according to their chemical group can be divided into two types:
At home, it is better to use only amine solutions, but with sufficient dexterity and experience, acids can be used to cure the epoxy resin.
A hardener for epoxy resin can be made by hand, but it is better to consider already proven products that have proven themselves. They have an incredible effect on the resin and therefore shouldn't be skimped on quality. It is better to purchase a product that is made according to all standards, and is also recommended by the manufacturer for a specific type of resin. Hardeners can be traditional or modified (that is, modern). The most budget-priced funds are produced by many companies, quite cheap, convenient to use, but still slightly worse in quality than modified expensive funds.
(included in adhesive and primer solutions, enamels) is an extremely popular material, and it is not difficult to work with it, even strict adherence to technology is not required. Can be used at room temperature. In appearance, PEPA will be a brown and viscous liquid, and therefore, where it is required to maintain the transparency of the material, the use of such a composition will not be possible. Up to 3/4 of the product is made up of uncontrolled impurities, and only 1/4 of the product will react with epoxy. This is the reason why PEPA should not be used for products that come into contact with water and food.
(i.e. triethylenetetramine) is a transparent liquid with a pungent aroma of imported production. It is a quality replacement for PEPA. In the description of the agent it is indicated that the impurities are not more than 4%, but in the composition there are fewer tertiary amino groups.
This will reduce room temperature polymerization and post cure should be done at elevated temperatures. Strict adherence to proportions and technique in working with such a tool is extremely important. Of the advantages, we highlight the following:
is a mixture of aminoesters of complex composition, which is yellow and non-viscous. Allows the resin to be diluted at room temperature. Consider the technical characteristics of the finished product:
DBT-2 in a mixture with resin is used to create filling compounds, self-leveling floors, and mixtures for bath renovation.
Modern compositions. What can replace the funds described above? The modified tools are devoid of many of the disadvantages of the traditional ones, but their cost is much higher. The finished products will have excellent strength properties because the resin is more fully polymerized.
The agents can act as plasticizers - sometimes they can even dilute and plasticize the resin.
Hardener for epoxy resin М-4 is an amine agent of a modified form, that is, a liquid with an increased degree viscosity, and the color is red-brown. M-4 should be mixed with epoxy in a volume of 1/5 to 1/4 of the base material. The substance can cure epoxy even at temperatures from +2 to +5 degrees, and this will not interfere with obtaining a product with increased strength. The fast curing agent is made on the basis of PEPA, and also improved in properties and composition.
Besides cold curing, even hot curing with M-4 can be done. The gelatinization and plasticization time at room temperature can be from 30 to 50 minutes, and at lower temperatures, the time increases.
Means No. 921
In the 921 series there are several types of hardeners, or rather 921 OP, just 921 and 921 T. These are low-viscosity substances, which make it possible to obtain unique epoxy compositions with high resistance to damage and ultraviolet radiation.
Finished products will not fade in the sun, and this effect is not achieved with every type of hardener. Most often, 921 series of products are used to coat boats, yachts, because the substance can be applied with a thickness of up to 5 mm, and the product itself can harden even thick layers of resin - up to 10 cm.For work, you need to mix everything in a volume from 45 to 55 % of the resin volume.
Means No. 620
UP-620 is an agent with a high degree of activity, and it can also harden the resin even in conditions with increased humidity level.
It is added to the resin in an amount of 15 to 17% of the total volume of the main product, and this is excellent enough to obtain a cold polymerization filling. The product is used as a part of compounds, self-leveling floors and plastic binders. It is allowed to use a hardener at temperatures from +15 degrees, and finished products are distinguished by excellent resistance to moisture.
An amine hardener that has no caustic odor and is non-toxic. It is required for the polymerization of epoxy resins and compounds at any level of humidity, temperature, even at -20 degrees.
It is one of the most important agents, and together with epoxy resin is used for the following purposes:
And one more tool in the end.
Aminophenol is used in the basis, and AF-2 is a mixed product - this is the result of combining phenol, amine and formaldehyde.The hardener makes it possible to cold cure the resin in the most unfavorable conditions - at a high degree of humidity, as well as at low temperatures.
It is added to the resin in a volume of 1/5 or 1/4 by volume of the total resin, at room temperature curing is 24 hours.
What proportions of epoxy and hardener should be used to properly dilute the components? Before starting work, you should prepare a mixing container, a wood stick, a couple of syringes for a set of substances. Beginners should remember that the ongoing reactions will be irreversible - it will not be possible to restore the damaged resin. It is better to do a small "test" mixing beforehand in order to accurately calculate the dosage.
Despite the possibility of cold curing with high quality products, it is worthwhile to slightly heat the resin.
This will make the composition not so viscous, but boiling and crystallization cannot be allowed (boiling will spoil the resin, and you can simply throw it away). When heating, stir the material regularly and monitor the temperature. Calculation of the rate is extremely important, because if you add a little solvent, the material will remain in the "gelation" stage, or will harden, but the surface will remain sticky. You should carefully read the instructions for the resin, and usually it shows all the proportions for dilution. All formulations vary, and the rate of the hardener can be 10-50%.
You cannot substitute hardeners for those that are not prescribed in the manufacturer's recommendations!
Please note that the required amount of the component should be collected in a pair of separate syringes. Some manufacturers produce material complete with a plastic bottle, where there are marks (like on a measuring cup). No needle is needed for pouring and can be removed. The thick resin is completely poured through the top of the syringe, and the piston is removed - it will not be drawn in through the narrow nozzle.
How to obtain a small volume of resin
Cold curing is usually used to obtain a small amount of formulation.
For this, the selected components are interconnected in containers, thoroughly and carefully mixed. You cannot use electric tools for this, and it is better to use a stick made of wood. The work is carried out at temperatures up to +25 degrees indoors. The finished mass should not contain air bubbles, impurities, and the composition should become transparent. If everything is done correctly, the consistency will be even, uniform.
Composition in large volumes
Since the polymerization of the resin will proceed with the release of heat, only small portions can be obtained by cold curing product. When connecting a large volume, the resin should be heated in a water bath to +50 degrees, and then the composition is removed and a hardener is added.It is impossible for water to get into the resin, because then all properties will be lost. You will have to work quickly after warming up the resin, so prepare the measured hardener and container in advance. All that remains is to mix and pour everything thoroughly.
Mixing the Components
Many resin brands require plasticizers to create a finished product. A number of hardeners have all the properties, and therefore it will be correct to use DBP and DEG-1. The hardener should be poured in a thin stream, and the composition should be thoroughly mixed with the other hand. Ideally, the pouring and mixing process takes 5 minutes.
Drying time will be determined individually, and the lower and upper limits of the period are indicated in the instructions.
Until dry, the resin will retain its viscosity, fluidity, and will be suitable for casting in various shapes and products. As a rule, when diluted in a ratio of 1 to 10 with hardener, the material should dry quickly - from 30 to 60 minutes. With a decrease in the amount of hardener, this time will increase to 3 hours, and as for epoxy glue, most hardens in a day. If the right time has passed, and the resin is still sticky, then the reasons may be as follows - very low temperature in the room, incorrect proportions, water got into the composition, or a poor-quality / expired hardener was used.
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