Disadvantages and Shortcomings of Powder Coatings

Although powder coatings have shown excellent performance in environmental protection and coating effects, there are also some shortcomings and deficiencies that need special attention:

1、 High requirements for construction conditions

Large equipment investment: Powder coatings require specialized spraying equipment, such as electrostatic spray guns, powder supply systems, curing furnaces, etc., which are expensive and have high initial investment costs. For some small businesses or projects with limited budgets, it may be difficult to afford.

For example, a complete powder coating spraying production line may cost tens of thousands or even millions of yuan, while the cost of traditional solvent based coating spraying equipment is relatively low.

There are limitations on the shape and size of the workpiece: Due to the principle of electrostatic adsorption, powder coating adheres to the surface of the workpiece. For some workpieces with complex shapes, deep holes or narrow slits, the powder is difficult to evenly cover, which can lead to uneven coating thickness and poor leveling.

For example, for some mechanical parts with complex internal structures, powder coating may not be able to effectively enter the deep hole, resulting in thin or even no coating on that part.

Strict requirements for construction environment: Powder coatings have high requirements for temperature, humidity, and cleanliness in the construction environment. Excessive or insufficient temperature can affect the flowability and solidification effect of the powder; Excessive humidity can cause powder to become damp and clump, affecting the quality of spraying; Dust and impurities in the environment can adhere to the surface of the workpiece, affecting the appearance and performance of the coating.

Generally speaking, the construction environment temperature of powder coating should be controlled at 15-35 ℃, and the relative humidity should be between 60% and 70%.

2、 Limitations in coating performance

Relatively poor weather resistance: Although the weather resistance of powder coatings is improved compared to traditional solvent based coatings, the coating is prone to fading, powdering, cracking, and other phenomena when exposed to harsh outdoor environments such as strong ultraviolet radiation, high temperature, high humidity, acid rain, etc. for a long time, which affects its appearance and service life.

For example, some outdoor billboards, building exteriors, etc. may be coated with powder coating, and after several years, the coating color may become noticeably lighter and small cracks may appear on the surface.

Lack of flexibility: Powder coatings are usually hard and brittle, with relatively poor flexibility. When subjected to external impact or bending deformation, the coating is prone to cracking, peeling, and other problems, which cannot meet some high flexibility requirements.

For example, some metal pipes that require frequent bending may crack during the bending process if coated with powder coating.

Chemical corrosion resistance has limitations: although powder coatings have a certain degree of chemical corrosion resistance, their protective ability is limited for some strong corrosive media such as strong acids and alkalis. Under the influence of these media, the coating may be corroded and damaged, resulting in the workpiece being corroded.

For example, in some chemical production workshops, equipment surfaces may come into contact with various chemical reagents, and if ordinary powder coatings are used for coating, they may not be able to effectively resist chemical corrosion.

3、 Inconvenient storage and transportation

Poor storage stability: Powder coatings are prone to moisture and clumping, which affects their performance. During storage, it is necessary to maintain a dry and ventilated environment to avoid contact with water vapor. Moreover, the storage period of powder coatings is relatively short, usually 6-12 months, and there may be a decline in performance after the expiration date.

For example, if the storage environment for powder coating is humid, the powder is prone to absorb moisture and clump, causing problems such as clogging of the spray gun during spraying.

High transportation costs: Due to the fact that powder coatings are powdery substances, special packaging and protective measures need to be taken during transportation to prevent powder leakage and moisture. This increases transportation costs and difficulty, while also limiting transportation distance and methods.

For example, powder coatings are usually packaged in sealed plastic bags or iron drums. During transportation, it is necessary to avoid severe vibrations and collisions, otherwise it may cause packaging damage and powder leakage.

4、 Difficulty in color replacement

During the powder coating spraying process, changing colors requires thorough cleaning of the spraying equipment, including spray guns, powder supply systems, curing furnaces, etc., to avoid mixing of powders of different colors. The cleaning process is tedious, time-consuming, and will waste a certain amount of powder coating, increasing production costs and time.
-For example, switching from one color of powder coating to another may take several hours or even longer to clean the equipment, while wasting tens or even hundreds of kilograms of powder coating.