What Is Urethane Paint?
To begin with, let us explain the characteristics of paint components: it is a mixture of pigments, resins, additives, and water or solvents as solvents. Resin plays an important role in determining the chemical properties of the paint and has a strong influence on the durability of the paint and the color and gloss of the finished product.
Urethane paint is paint that contains urethane resins as the resin component and can be produced at a low cost. The least expensive paint is acrylic paint, but it is the next most expensive.
This paint contains urethane paint as a resin component, which is highly flexible and thus provides high adhesion. It has also been used in a wide range of applications because of its beautiful gloss and luxurious appearance.
Currently, demand is on the decline as silicone-based paints with high durability are becoming mainstream, but they are still popular due to their low cost and high versatility.
Uses of Urethane Paints
Urethane paints are used to paint exterior walls, motorcycles, and furniture. While relatively inexpensive, they are known as highly convenient paints due to their superior gloss, elasticity, and adhesion. They are also used for DIY projects because they are easy for amateurs to handle. Recently, spray-type urethane paints have been sold at home centers and are readily available. Commercial urethane paints are often highly volatile oil-based paints, so rubber gloves and a mask are essential.
Characteristics of Urethane Paints
As explained at the beginning of this article, urethane paints contain urethane resin as its component. This resin component contributes greatly to the chemical properties of urethane paints, such as its durability and unique color and gloss after painting.
This material is synthesized by the polymerization reaction of the polyol with multiple hydroxyl groups and polyisocyanate. By changing the combination and mixing ratio of polyol and polyisocyanate, it is possible to develop paints with various properties.
In the application, the paint is dissolved in water or a solvent, diluted, and then applied. This dilution process not only makes the paint easier to handle but also increases its adhesion. Depending on the solution dissolved in the paint, the paints are broadly classified into water-based, oil-based, and elastic paints.
- Water-based Paint: Water-based paints are diluted with water and are highly convenient because they suppress the odor characteristic of paints. However, because it contains water, it is more susceptible to external factors such as temperature and humidity.
- Oil-based Paint: Diluted with solvent, oil-based paints are inexpensive and reduce the work process. However, there are some disadvantages, such as strong solvent odor and risk of ignition.
- Elastic Paints: Elastic paints use an elastic compound as a hardener to provide elasticity. Because of its high elasticity, it has the advantage of being less prone to cracking. However, care must be taken because if not used properly, heat dissipation will deteriorate and adhesion will decrease.
Difference Between One-Component Urethane Paints and Two-Component Urethane Paints
Two types of urethane paint exist: one-component and two-component. In one-component type, a hardener is added in advance to the main agent, and the coating can be applied by itself. They are classified into water-based and oil-based types based on differences in solvent solubility and are diluted with water or a solvent before use. On the other hand, two-component types are prepared separately with a base agent and a hardener, which must be mixed before use. Two-component types are also available in two types: water-based and oil-based, based on their solvent solubility, and are diluted with water or an appropriate solvent before use.
Advantages of Urethane Paints
The primary advantage of urethane paints is its high functionality. Compared with other paints, urethane coatings have a softer coating film and can accommodate changes in the shape of the wood over time. The unique glossy finish of urethane coatings also makes them ideal for use on high-end furniture and flooring.
This paint is also used as a base coat for exterior walls due to its high adhesion. The adherent coating film is effective in reducing the occurrence of cracks.
In addition, two-component urethane paints mixed with a hardener have been developed, resulting in a high degree of versatility. The two-component type is characterized by a dense coating film formed in a mesh structure.
Disadvantages of Urethane Paints
There are four disadvantages of urethane paints.
The first is that the durability is only 6 to 10 years, which is inferior to other paints. However, since it is a low-cost paint with good performance, it can be considered the best paint for a new paint job.
Second, there is a risk of discoloration. Urethane paints are prone to discoloration caused by ultraviolet rays. Exterior walls and roofs that are exposed to ultraviolet rays during the day are easily affected and may turn yellow.
Third, they are vulnerable to water. The curing agent in urethane paints reacts easily with water. Therefore, when painted in a humid environment, for example, the hardener reacts with moisture in the air, and the performance of the coating film may deteriorate. Therefore, it is necessary to be alert to the weather, humidity, and other environmental conditions at the time of use.
Fourth, there is a risk of expansion of the paint film. In the case of exterior walls with insulation, heat is trapped between the exterior wall and the paint film. As a result, there is a risk that the heat will cause the paint film to expand and peel off. This phenomenon is not only caused by heat but also by air that enters through rust, hand stains, or other foreign objects.