We know that the coloring of pigments in plastic applications is formed by the height of the particle state. It always maintains the original crystal state during the decentralization process; the solvent dye is the purpose of solving the color in the form of solubility. Here, we should pay attention that the dispersal of the pigment is affected by various factors, such as the crystal of the pigment, the original particle size and distribution (the small particle size is not easy to disperse), the surface polarity and other factors. In a strict sense, solvents dyes do not have any dispersion problems.
In the actual production process, what we encounter is not the case. Taking solvent red 135 as an example, many customers feedback solvent red 135 will have decentralized problems during the production process. It is manifested as a different number of black spots in the product. Black spots increase with the increase of color powder, decreased with the increase in temperature.
From the perspective of performance, this phenomenon and decentralization problems have certain similarities. Therefore, we copied the customer's production conditions to find out.
During the PS injection processing process, we added a solvent red 135 of 0.5-1%, and the injection molding temperature was set at 210 degrees. It was found that a small amount of black spots were already appeared at a ratio of 0.5%, and the number of black spots increased rapidly with the increase of the amount.
Under the same conditions, we replaced the color powder to 230 solvent red, and found that under the condition of 0.6-1%, the use of solvent red 230 did not have any black spots.
Under the same conditions as experiments, we increase dispersion by increasing auxiliary agent and other additives such as shear and adding dispersions. The experimental results are consistent with the first time.
During the PC injection processing process, we added a solvent red 135 of 0.5-1%, and the injection molding temperature was set at 300 degrees. It was found that only a small amount of black spots appeared at a ratio of 1%.
Under the same conditions, the solvent red 230 does not have any black spots.
According to the above three experiments, we can obtain the following inference that the so -called "decentralized" problem with solvent dyes is not our practical decentralization. The emergence of black dots should be related to the characteristics of the solvent dye, processing temperature, and resin.
In the process of using solvent dyes, in addition to focusing on conventional characteristics such as color light and temperature resistance, we often ignore a element, that is, the melting point. The "decentralization" of the melting point and the solvent dye is not small. In the process of application, we often find that those high -melting solvents dyes have more or less black spots similar to solvent red 135. In addition to the solvent red 135 (melting point 315-320 degrees), similar products include yellow yellow 147 (solvent type pigment, melting point 300 degrees), solvent yellow 157 (melting point 323 degrees), solvent orange 63 (melting point 320 degrees), solvents Purple 49 (melting point 300 degrees), solvent brown 53 (melting point 350 degrees), etc.
In addition, we can get it from the third experiment that the processing temperature and resin type have a certain impact on the "decentralization" of solvent dyes.
We used the solvent blue 104 in the same proportion in PS and PLA, and found that the blue concentration presented by PLA was higher and the color light was gorgeous. The two resins are different from the affinity of dyes. High -affinity resin can dissolve more dyes under the same conditions, so it shows better color light and "decentralized".
The higher processing temperature can help high melting solvents dye to achieve better dissolution. The closer to the melting point, the solvent dye shows stronger solubility.
The dispersion of solvents dyes we often encounter is often a comprehensive effect of several conditions. The processing temperature failed to reach the melting point, and the pursuit of high -color force and the use of large doses of color powder, causing cannot be completely dissolved. This is particularly obvious in the application of polyester spinning. Therefore, we can further understand the advantages of high -color, high -soluble, and low -melting dyes such as solvents red 230 in the spinning application.
At present, we have begun to test the solubility of solvent dyes and different resins. Because there are many types of resin, and each resin has many brands, we will choose some representative resins and brands for testing and records.