The preparation is troublesome, and the proportion of promoter and initiator is strict. The activation period after paint preparation is short and must be completed within 20-40 minutes, otherwise it will be gelatinized and scrapped. Therefore, it is necessary to prepare as much as needed. In addition, its repair performance is also poor, and the damaged paint film has prints after repair. The polyester paint needs to be cured during construction, and the amount of these curing agents accounts for one third of the total amount of paint. These curing agents are also called hardeners, and their main component is TDI (toluene diisocyanate). These free TDI will turn yellow, which will not only make furniture paint yellow, but also make adjacent walls yellow, which is a major disadvantage of polyester paint. At present, yellowing resistant polyester paint has appeared on the market, but it can only be used as "yellowing resistant" paint, which cannot completely prevent yellowing. In addition, the free TDI beyond the standard will also cause harm to the human body. The main harm of free TDI to human body is sensitization and stimulation, including pain and tears, conjunctival congestion, cough and chest tightness, shortness of breath and asthma, red papules, maculopapules, contact allergic dermatitis and other symptoms. The international limit standard for free TDI is below 0.5%.
In the 1990s, after polyester paint was introduced into China, it soon replaced varnish and became the main paint for furniture. Polyester paint has many advantages. It is not only rich in color, but also thick in paint film. It can be sprayed for two or three times, and can completely cover the materials of the base layer. Therefore, furniture can be directly brushed with polyester paint on the density board, and the requirements for the base layer materials are not high. The film of polyester paint has excellent comprehensive performance. Because of the use of curing agent, the film has higher hardness, hardness, wear resistance, high richness, and high insulation resistance to damp heat, dry heat, acid and alkali oils, solvents, and a variety of chemicals. The varnish has light color, high transparency and gloss, good light and color retention performance, and good protection and decoration. Unsaturated polyester paint has poor flexibility and is easy to crack under stress. Once the paint film is damaged, it is difficult to repair, so attention should be paid to protecting furniture when moving.