Introduction to Polyurethane Enamels
Enameled wirevarnish is coated on the surface of copper wire or aluminum wire. After baking, it can form a kind of product with electrical insulation and certain mechanical strength, heat resistance and chemical resistance. It is mainly used for electromagnetic wire manufacturing. Some products may also have other uses, such as the production of decorative metal wires, or other insulating and heat-resistant coatings. Polyurethane paint is one of them, let’s take a look at this kind of paint today.
Polyurethane paint is polyurethane paint. It has strong paint film, full luster, strong adhesion, water resistance, wear resistance and corrosion resistance. It is widely used in high-grade wooden furniture and can also be used on metal surfaces. Its shortcomings mainly include problems such as foaming when it is wet, and powdering of the paint film. Like polyester paint, it also has the problem of yellowing.
Classification of Polyurethane Enamels
The varnish variety of polyurethane paint is called polyurethane varnish. Polyurethane enamels is divided into one-component and two-component. The characteristics of one-component polyurethane paint: oil-modified polyurethane paint has the advantages of stable storage, fast drying of the paint film after coating, good wear resistance, alkali resistance, oil resistance and solvent resistance, but poor weather resistance, which is not suitable for outdoor use. Moisture-curing polyurethane paint has the functions of fast drying, good adhesion, wear resistance, water resistance, moisture resistance, and acid and alkali medium erosion resistance, and can be used for anti-corrosion coatings and cement surface coatings in underground projects. Sealed polyurethane paint (high temperature baking type) has the properties of stable storage, low toxicity, oil resistance, solvent resistance, acid resistance and alkali resistance, as well as electrical insulation, heat resistance and cold resistance, and is generally used for metal anti-corrosion coatings.
Features of two-component polyurethane paint: Hydroxyl curable polyurethane paint has the advantages of being able to dry at room temperature, low toxicity, tough paint film, high gloss, good adhesion, corrosion resistance, oil resistance, and water resistance. It is suitable for metal, cement, etc. , wood, rubber, leather and other materials. Catalytic curing polyurethane paint coating has good oil resistance, water resistance, acid and alkali resistance, organic solvent resistance, and has good adhesion and wear resistance. It is generally used as a surface coating for wood, concrete, etc. (such as wood floor paint).
Advantages of Polyurethane Enamels
Polyester paint has many advantages. The characteristic of polyester paint is that acyclic and/or circular hydrogen bonds can be formed between polymer molecules. Under the action of external force, the hydrogen bonds can be separated and absorb external energy (20~25kJ per mole). When the external force is removed, hydrogen bonds can be re-formed. The reversible repetition of such hydrogen bond splitting and re-formation makes the polyurethane paint film highly mechanically wear-resistant and tough. Compared with other paints, under the same hardness conditions, due to the effect of hydrogen bonds, the polyurethane paint film has the highest elongation at break, so it is widely used as floor paint, overtime paint, high decorative anti-corrosion paint, etc.
The paint film has strong adhesion. Polyurethanes, like epoxies, formulate into excellent adhesives. Therefore, the coating film has excellent adhesion to various surfaces (metal, wood, rubber, concrete, some plastics, etc.). The author’s experience is that: for some metal surfaces, the adhesion of polyurethane paint is slightly inferior to epoxy paint; but for rubber, polyurethane paint exceeds epoxy paint.
Polyurethane paints can be dried at high temperatures and cured at low temperatures. Among the typical room temperature curing coatings: epoxy, polyurethane, and unsaturated polyester, epoxy and unsaturated polyester are difficult to cure below 10°C, and only polyurethane can be cured normally at 0°C, so it is the best season for construction. long. Because it can quickly solidify at room temperature, it can be applied at room temperature for large-scale projects such as large oil tanks and large aircraft to achieve better results than ordinary baking paint. Some varieties of coatings (such as epoxy, chlorinated rubber, etc.) have good protective properties but poor decorative properties; some varieties (such as nitro paint, etc.) have good decorative properties but poor protective properties. However, polyurethane paint has both protective and decorative properties, and can be used for coating high-grade wood, pianos, and large airliners.
Application of Polyurethane Enamels
This kind of paint film is bright and plump, hard and wear-resistant, resistant to oil, acid, chemicals and industrial waste gas, has good electrical properties, and can be miscible with various resins. The formula can be adjusted in a wide range to meet different needs. Widely used in wood, automobiles, aircraft, machinery, electrical appliances, instruments, plastics, leather, paper, fabrics, petrochemicals, etc.
