Polyurethane and its derivatives are widely used polymers in various industries around the world. The formulation of these polymers is such that it covers a wide range of complex, dry, and compact materials. Polyurethanes are composed of an additive reaction between the isocyanate and hydroxyl functional groups. If a diamine reacts with isocyanate instead of alcohol, the resulting polymer falls into the polyurea family.
Isocyanate groups are highly reactive and therefore do not require an increase in temperature to advance their reaction. The most important feature of this group of polymers is that a stable structure is formed after the reaction.
Autobire made the first polyurethanes in 1937 during a reaction between a chain diisocyanate and a diamine. The isocyanate functional group reacts with any molecule that has active hydrogen.
Therefore, compounds such as carboxylic acids and amines, like the hydroxyl group, have active hydrogen and can react with isocyanate. Hence, when it comes to polyurethanes. Countless species of these substances can be considered. Therefore, the variety of reactants exposed to isocyanates leads to the production of polyurethanes in different types with different characteristics. The properties of all polyurethanes are derived from the effect of polyols on isocyanates. The number of these groups In a molecular structure and how they are placed next to the primary chemical structure of each material is significant in determining the properties.
Polyurethanes resin flooring for homes are a group of high-consumption polymers with excellent properties. Therefore, designers and specialists in the coating industry can use these compounds in various applications. There are several examples of the many applications of these compounds, including transparent coating for single-layer coatings for roofs and colors to specify the pedestrian crossing.
Aliphatic polyurethanes are more expensive than aromatic ones. For this reason, aromatic types and epoxy samples are used in esters, base colors, and interface coatings. At the same time, aliphatics are specific to the final coating.
Polyurethane dispersion resins (pud)
The conventional method for making water-based polyurethane dispersion resin floors prepares a prepolymer with the final isocyanate group, which modifies the polyol in the chain structure to form the carboxylic acid functional group. Water is dispersed to form ionic centers. In this way, the polymer particles become stable.
In some mixtures, the molar ratio of NCO to OH groups is precisely 2 to 1. In the molar ratio of about 1 to 1, the viscosity is very high, and the preparation of polyurethane dispersion resin flooring or domestic resin flooring is complex. There is also a risk of untimely jelly. But if this ratio is less than 1.5 to 1, the risk of jelly is reduced.
Ice is used to lower the temperature while preparing polyurethane mixtures quickly. As a result, the reaction rate between the water and the isocyanate group decreases. The prepolymer should react with the NCO terminal group with the amino chain enhancer. However, dispersing the prepolymer in water, especially in an industrial unit, requires some time. In any case, adverse reactions between water and isocyanate occur. By cooling the neutral mixture to below 5 ° C, side effects are minimized.
Polyurethane and polyurea – similarities and differences
Polyurethane chemistry is based on the exothermic reaction between di or polyisocyanate and compounds containing the hydroxyl terminal group, such as polyols, or mixtures having active hydrogen, such as amines.
This difference in structure justifies the reaction time quickly and consequently the gelling, surface drying, and complete drying time of polyurea faster than polyurethane.
The C-N bond in the polyurea structure is stronger than the C-O bond in the polyurethane elastomer. This property results in better thermal durability of polyurea than polyurethane. As a result, the 100% solid polyurea system exhibits better thermal durability and anti-dandruff properties than polyurethane elastomers.
100% solid polyurea elastomer coatings include soft and hard block structures. The diisocyanate component acts as a hard block, and the polyetheramine acts as a quiet block. In particular, amines have a smooth and flexible polyoxypropylene backbone, which, unlike polyurethane, leads to polyurea’s hydrophobic/waterproof nature.
The polyurea coating is not sensitive to moisture and does not show moisture-related defects such as bubbles, foam, and swelling. Be. Because the presence of a catalyst in the system increases the degradation and degradation of the polymer properties under these conditions. Aromatic urea has a slightly higher tendency to yellowing polyether amines and other amine reactants than polyurethanes based on the hydroxyl of the first poly.
In today’s world, polyurea has proven to be an effective and economical choice in protective and anti-corrosion coatings and related industries.
The production of products with improved properties and the most advanced equipment and spraying to achieve the best quality and meet the demands of consumers every day increases the popularity of this coating in the world’s industries.
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