News Details
The powder coating USES crosslinking agent
2017-5-3 16:27:26
The powder coating USES crosslinking agent. The auxiliary agent plays a very important role in the formulation of powder coating, so that it has become an indispensable part. According to Richart, the "ideal" powder coating agent should have the following characteristics:
1) solid, preferably melting point or glass temperature at above 50 degrees.
2) chemical inertia, which is no chemical reaction to the resin substrate or crosslinking agent.
3) it has certain functions.
4) 100% activity.
5) low levels of possible conditions can help. Unfortunately, a lot of useful auxiliary is liquid, so they must be added to the resin adsorption on the silica carrier or done in masterbatch, to convenient for application. In the following sections we will classify various powder additives.
In addition to membrane resin, crosslinking agent for thermosetting powder coating is the most important part of coating composition. They can produce the production, storage and application of coatings, such as extrusion temperature, storage stability, crosslinking time, crosslinking temperature and flow property, impact resistance and hardness, weather resistance and chemical resistance, and so on.
Crosslinking and membrane resins are sometimes difficult to distinguish, as these two components eventually form a complete adhesive system. The low molecular weight compounds in the adhesive system are often seen as crosslinking agents.
After powder coating crosslinked to form surface condition, depends largely on the melting and flow in the process of the flat surface tension (driver) and viscosity (resistance), on the one hand, low surface tension can provide good spreading molten powder and substrate, but if the surface tension is too low, will influence flow leveling effect, may produce orange peel phenomenon. On the other hand, if there is an unbalanced surface tension, the melting powder can cause defects such as shrinkage. Therefore, surface tension plays an extremely important role in the fusion of powder coating and flow. Therefore, the relationship between surface tension and coating flow must be described before discussing the fluid.
In order to discuss convenience, the flow of powder coating is divided into two stages. The first is the fusion of powder particles into a continuous membrane (fusion phase), followed by a continuous membrane to flow (phase).
In the process of particle fusion, the theory is usually explained by the Nix and the Dodge equation. They believe that the surface tension is the only factor in the fusion and flow flattening of a fixed powder coating. Based on this hypothesis, the two particles fuse together with the melt viscosity (mu) and the curvature radius/surface tension (Rc/gamma) ratio of the particle. Equations as follows t ∝ mu Rc/gamma
Chinese name: Diethyl toluene diamine(DETDA)
Physical and chemical properties: light yellow transparent liquid, slightly soluble in water, soluble in alcohols, ethers, ketones and other polar organic solvents, and polyether, polyester polyol compatibility.
Density 1.022
Viscosity (20 ℃) ??mPa·ss290±10
Pour Point ℃-9
Boiling point of310°C
Flash Point°C161.1°C
Although this model is based on single circular particles, in fact is not completely real particles is equal to the ideal model (size is not the same). But what is certain is the higher the gamma fusion between particles should be shorter, u need time to grow more, the higher the fusion from the point of the phenomenon of final Nix and Dodge equation can better explain the phenomenon.
In the second phase of powder coating flow (see above), we can describe the Orchard equation that describes the flow of liquid coatings. The equation will flow leveling time and coating thickness (h), melt viscosity (mu), surface tension (gamma), wavelength (lambda), wave height (alpha t, alpha 0) for correlation equation are presented: ln (alpha t/alpha 0) = - 4 h3 (16 PI / 3 lambda. 4) t ∫ 0 (gamma/mu) dt
Assume that powder coating viscosity at a given temperature does not change over time (for most thermoplastic powder is established), the integral type orchard equation can be expressed as t = 3 lambda 4 mu ㏑ (alpha t/alpha 0) / 16 PI 4 h3 gamma
Orchard equation shows that in order to obtain good leveling effect (that is, the shorter flow flat), higher and lower the surface tension of the melt viscosity is necessary, it is the same with the first stage of the fusion process.
In the two phases of powder flow, the surface tension is the driving force, and the melt viscosity is the resistance. The larger surface tension and the lower melt viscosity help to fuse and flow flat.
However, low melting viscosity leads to the phenomenon of flow hanging. Therefore, proper balance must be made in order to ensure a good flow.
Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd
Diethyl toluene diamine(DETDA) http://www.yaruichem.com
1) solid, preferably melting point or glass temperature at above 50 degrees.
2) chemical inertia, which is no chemical reaction to the resin substrate or crosslinking agent.
3) it has certain functions.
4) 100% activity.
5) low levels of possible conditions can help. Unfortunately, a lot of useful auxiliary is liquid, so they must be added to the resin adsorption on the silica carrier or done in masterbatch, to convenient for application. In the following sections we will classify various powder additives.
In addition to membrane resin, crosslinking agent for thermosetting powder coating is the most important part of coating composition. They can produce the production, storage and application of coatings, such as extrusion temperature, storage stability, crosslinking time, crosslinking temperature and flow property, impact resistance and hardness, weather resistance and chemical resistance, and so on.
Crosslinking and membrane resins are sometimes difficult to distinguish, as these two components eventually form a complete adhesive system. The low molecular weight compounds in the adhesive system are often seen as crosslinking agents.
After powder coating crosslinked to form surface condition, depends largely on the melting and flow in the process of the flat surface tension (driver) and viscosity (resistance), on the one hand, low surface tension can provide good spreading molten powder and substrate, but if the surface tension is too low, will influence flow leveling effect, may produce orange peel phenomenon. On the other hand, if there is an unbalanced surface tension, the melting powder can cause defects such as shrinkage. Therefore, surface tension plays an extremely important role in the fusion of powder coating and flow. Therefore, the relationship between surface tension and coating flow must be described before discussing the fluid.
In order to discuss convenience, the flow of powder coating is divided into two stages. The first is the fusion of powder particles into a continuous membrane (fusion phase), followed by a continuous membrane to flow (phase).
In the process of particle fusion, the theory is usually explained by the Nix and the Dodge equation. They believe that the surface tension is the only factor in the fusion and flow flattening of a fixed powder coating. Based on this hypothesis, the two particles fuse together with the melt viscosity (mu) and the curvature radius/surface tension (Rc/gamma) ratio of the particle. Equations as follows t ∝ mu Rc/gamma
Chinese name: Diethyl toluene diamine(DETDA)
Physical and chemical properties: light yellow transparent liquid, slightly soluble in water, soluble in alcohols, ethers, ketones and other polar organic solvents, and polyether, polyester polyol compatibility.
Density 1.022
Viscosity (20 ℃) ??mPa·ss290±10
Pour Point ℃-9
Boiling point of310°C
Flash Point°C161.1°C
Although this model is based on single circular particles, in fact is not completely real particles is equal to the ideal model (size is not the same). But what is certain is the higher the gamma fusion between particles should be shorter, u need time to grow more, the higher the fusion from the point of the phenomenon of final Nix and Dodge equation can better explain the phenomenon.
In the second phase of powder coating flow (see above), we can describe the Orchard equation that describes the flow of liquid coatings. The equation will flow leveling time and coating thickness (h), melt viscosity (mu), surface tension (gamma), wavelength (lambda), wave height (alpha t, alpha 0) for correlation equation are presented: ln (alpha t/alpha 0) = - 4 h3 (16 PI / 3 lambda. 4) t ∫ 0 (gamma/mu) dt
Assume that powder coating viscosity at a given temperature does not change over time (for most thermoplastic powder is established), the integral type orchard equation can be expressed as t = 3 lambda 4 mu ㏑ (alpha t/alpha 0) / 16 PI 4 h3 gamma
Orchard equation shows that in order to obtain good leveling effect (that is, the shorter flow flat), higher and lower the surface tension of the melt viscosity is necessary, it is the same with the first stage of the fusion process.
In the two phases of powder flow, the surface tension is the driving force, and the melt viscosity is the resistance. The larger surface tension and the lower melt viscosity help to fuse and flow flat.
However, low melting viscosity leads to the phenomenon of flow hanging. Therefore, proper balance must be made in order to ensure a good flow.
Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd
Diethyl toluene diamine(DETDA) http://www.yaruichem.com
Spanish
French
Italian
Portuguese
Japanese
Korean
Arabic
Russian