Description and types of paint hardeners, proportions and what to replace
Paint or enamel is applied to the surface, from a liquid state the material becomes solid and is not washed off. Some types of dyes are not able to harden on their own. For them, polymerizing components are used. These chemicals are called paint hardeners. They are added to the composition to obtain an infusible and insoluble product. The substances give plasticity and durability to the paint and lacquer film.
General description and purpose
By hardener, we mean a chemical compound added to the composition of the dye. Gives the structure stable properties. The construction market offers a wide selection of additives, which, according to the technical characteristics, are able to change the physicochemical properties of paint and varnish coatings.
Curing agents are added to the coloring composition immediately before use, so that premature solidification of the material does not occur. The additive is stored in its original packaging to avoid the loss of properties. If you pour the hardener into another container, it will deteriorate after a few hours.
Advantages and disadvantages of using
Adding a component to paint coatings has the advantage of giving the composition improved characteristics:
- The paint material becomes resistant to sunlight;
- the service life of the coating increases to several years;
- the hardener accelerates the setting;
- For some types of paints, the component gives a brilliant shine, the product does not need to be varnished;
- paint with a hardening component does not crack, has increased resistance to mechanical damage.
Of the minuses, the means are distinguished by storage features. When the lid is not tightly closed, air enters the container, a reaction occurs, the composition hardens and becomes unusable. After adding a component to the paint, the pot life of the material is reduced, so you need to start working with the mixture immediately after preparation.
Varieties
Materials differ in purpose and composition. The chemical composition of the additives affects the curing time and the durability of the coating. The purpose of additives depends on these properties. They are divided into two main groups.
Dryers
Refers to substances that accelerate the hardening of oil-containing film formers. The structure contains binding elements which dry out when oxygen is oxidized. The film is formed in several stages. First, the painted surface is supersaturated with oxygen and peroxides are formed.
Then the substances are split, free radicals appear. In the last step, polymers are formed. The catalysts are easily miscible with paints and varnishes.
Hardeners
Chemicals added to two-component paints and varnishes to obtain an insoluble product.They are used as an additive in acrylic, polyurethane and epoxy paints and varnishes. When combining products, exact proportions are required.
What are paints used for?
Substances are added to paint materials with a two-component composition, intended for decorating surfaces made of concrete, metal, wood. Products coated with such a composition have improved performance.
Additives for acrylic-based paints and varnishes are produced in two different containers and mixed before use. The composition of the high molecular weight compound contains esters. For alkyd paint materials, it is used as a second component for alkyd primers, enamels and varnishes. A curing accelerator is added to PF-115, providing high quality enamel paint and coating properties. Wood and metal surfaces are painted with enamel.
Application in practice
The consumption and the chemical nature of the additive are chosen to obtain a good material flow and a good drying speed. The proportions are strictly observed when mixing the components. Manufacturers on the package indicate the exact amount of additive for each type of paint. Different types of hardeners are suitable for certain types of paints.
How to enter correctly?
Before mixing the components, carefully read the instructions. A clean container is prepared, which is filled with a base, then a hardener is added. To obtain a viscous state, a solvent is added, which is introduced at the very end. If the dye runs out for a long time, a secondary dilution is performed. Usually, the manufacturer indicates the proportions in parts; for convenience, a graduated container is prepared.For example, to achieve a 2:1 ratio, mix two parts paint and one part hardener.
The curing agent is added to the composition before use. The resulting mixture is thoroughly mixed with a drill with a mixing nozzle. After preparing the working solution, it should be used within 5 hours. After this time, the material deteriorates and is no longer subject to further use.
Proportions
Too little or too much accelerator leads to cracking of the coating, shortening the service life. Therefore, it is imperative to observe the dosage indicated by the manufacturer. On average, the ratio of hardening component to paint is 5 to 25 percent.
Incorrect proportions can lead to clouding of the varnish, a change in the homogeneity of the composition of the paint. Insufficient amount of hardener will cause the coating to dry out for a long time or may remain soft. In some types of paints, it is allowed to exceed the dosage of the additive, but not more than 10 percent.
What can be replaced?
The main task of the substance in the process of solidifying is to change the molecular structure, to carry out polymerization. Substances enter into the reaction: acids, amines, diamines and anhydrites. All of them are divided into base and compositions. These substances include:
- polyethylene polyamine (PEPA) - a mixture of ethylene amines, easily soluble in water and alcohol, absorbing moisture from the air;
- triethylenetetramine (TETA) is a low viscosity liquid, the curing process takes place at high temperature;
- aminoacrylate.
Dicarboxylic acids are used as a hardener for epoxy resin: sulfuric, orthophosphoric, ammonia and dry alcohol, and other substances.
Additional tips and tricks
Before mixing paint and varnish with a hardener, it is recommended to mix a small amount of components in a separate container. The reaction of these substances is irreversible, therefore, in case of error, the material will be damaged. The temperature regime affects the polymerization reaction, the higher the indicator, the faster the solidification of the substance occurs. It is advisable to mix the working solution in small portions in order to have time to develop the mixture before it solidifies. The final solidification of the material takes place 24 hours after application.
Hardener for paints and varnishes can be made by hand.But the wide range and abundance of products allows you to choose the right supplement without experimenting. It is advisable not to save money and choose only material from proven brands.
In two-component paints, the use of a hardener is mandatory, otherwise the coating will dry out for a long time or not harden at all. The additive becomes one of the main players in the polymerization process, merges with the base, giving it high performance.