Plastic particles of color matching method

1. Visual color matching

An experienced colorist must have a clear idea of the colorant he needs before matching the color. to master the general law of colorant mixing coloring, we should also have a clear understanding of the properties of the colorant used, such as tone, color light, mobility, heat resistance, weather resistance, chemical stability, and so on, and accumulate representative plastic coloring samples and color matching. before finding a suitable colorant formula, a large number of tests must be carried out, and the same color is repeatedly toned until the desired color is obtained. obviously, visual color matching is a trial-and-error method, not very scientific. because this method is simple and practical, it is still widely used today. However, this method is very time-consuming and requires the operator to have rich experience, otherwise it will be difficult to operate.

2. Instrument matching

The instrument color matching method is derived from the visual color matching method. this method uses spectrophotometers and other measuring instruments to replace the functions of the human eye and brain. the trial-and-error process for color proportions is carried out by computer simulation without the actual mixing of the plastic for coloring. the operator only needs to measure the reflectivity, which is its standard value, and select the pigment to match the color. by adjusting the concentration of matching pigments, the measuring system is made consistent with the standard conversion value. If the operator chooses the right pigment, the system outputs a formula in the form of a mass fraction, and then converts the percentage formula into a mass ratio.

If you know (qualitatively) what formula of coloring agent is used in the sample, the computer can easily calculate the actual amount of various coloring materials in the formula. however, often do not know the formula of the colorant used by the sample, in this case, the color coordinate of the sample can be used to match the color. there are many analytical and empirical relationships used to select the appropriate colorant formulation and to determine the concentration to be applied to each formulation. the establishment of these relationships requires a lot of calculation. using a computer can shorten the time of the whole color matching process to ten minutes.

A color can be formulated from several formulations containing different pigments. these formulations differ in their performance characteristics and composition. color matching instruments and computers can be used to obtain a variety of formulas of a color, for the color matching operator to choose to see whether it is economical to use a small amount of expensive organic pigments, or to use a large number of cheap inorganic pigments, so that people have a larger range of choices.

In addition, both instrumental and visual color matching of fluorescent materials is difficult, because fluorescence is a new variable, and different results may appear when two samples are compared under different light sources. not only will the light source affect the observation of the sample, but the angle between the incident light and the observation position will also affect the observation of the sample.

Precautions

Color palette when the first to pay attention to the color of the colorant, each colorant in addition to its natural color, there are their own color light, that is, compared with the determined standard color of the relatively minor pigments, that is, called color light. Such as phthalocyanine green with yellow light, chromium yellow with red light and so on. If medium chromium yellow is mixed with phthalocyanine green, it is necessary to avoid the intervention of red light of medium chromium yellow, there is a combination of red, yellow and blue three basic colors, so that the matched color is dark. Therefore, in order to obtain bright colors, when the two colorants are combined, pay attention to the interference of conflicting colors. In the actual preparation of pure red, can use risor bright red and fast bright red color combination, is their yellow, blue (purple) and other color light offset, while adding white colorant to improve its brightness.