Application of Color Management in Printing and Dyeing Practice (II)

3.2.2.1 Introduction to FMCII Color Difference

(1) First, find the 25 ellipse-related chromaticity points that are the standard deviations of the color match of McAdam: (2) Then generalize this result to the entire chromaticity diagram range so that you can draw a color matching at any point. Ellipse: (3) MacAdam-Brow also obtained the standard deviation ellipse of color and color matching in three-dimensional space by the same experimental method; (4) finally Formulated by Friele, Macadam-chckering, FMC-II formula, which can be used For colorimetric calculations, the results of the calculations have a good correlation with human eye evaluation. This formula is used more often in the United States.

3.2.2.2 JPC79 color difference formula introduction

The JPC79 color difference formula is based on the comprehensive evaluation of the human eye to the color difference of the fiber products, and the correction of the ANLAB color difference formula is established. Its contribution is that the JPC79 considers the contribution of brightness, saturation and hue to the textile color difference respectively. Afterwards, different correction coefficients are given so that the color difference calculated by the formula has a better correlation with human visual color difference.

3.2.2.3 Introduction to CMC (I:C) Color Difference Formula

The CMC formula is a modification of the CIELAB formula. The CIELAB calculation of ?L*?C*?H** is modified. The parameter C is added to adjust the coefficient of saturation for a relatively wide capacity. These two important correction factors are The general color difference can be observed when the sample is evaluated (ie, a large color difference occasion). I = C = 1, this formula CMC (1:1), for the sample evaluation of the color difference is acceptable, then take I = 2, C = 1, CMC (2:1) formula.

3.2.2.4 CIE1994 color difference formula

CIE1994 color difference calculation formula, at present does not establish the official standard, still drafting the standard stage, so did not choose to use temporarily. The above formulas are based on several color areas, and it is considered that the CMC (2:1) is more in line with the visual results. Therefore, the CMC (2:1) is selected instead of CIELAB (1976) and others. CIELAB should be used together.

3.2.3 color professional managers to optimize the combination

In the color management personnel combination, whether it is based on computer personnel or samplers, or dye engineering technicians. The experience based on our practice is mainly based on dyeing engineering technicians, and the form of uniting the combined personnel is appropriate, which is consistent with the domestically more successful experience.

3.2.4 Some Problems in Color Management Affect Color Controllability

The standardization of dyestuffs and raw materials, the setting of domain limits for large and small sample color differences, and the relationship between factors such as process, equipment, water quality, and raw materials on color controllability. Among these factors, dyestuffs are the most important. Color differences between large and small samples are the most important. Their effects on color controllability are described below.

3.2.4.1 Correction of Dye Color Matching

Many people have considerable concerns about the quality stability of domestic dyes when they purchase computer color matching instruments. Objectively, domestic dyes currently have a certain gap with imported dyes, but they will not be so serious that they cannot be color-matched. However, it is necessary to grasp the following: (l) The key is the choice of dyes, and the compatibility is better; (2) It must be fully applied. The function of the color matching software, such as the dye quality, is mainly expressed as the fluctuation of the force, first calculate the correction coefficient of the force, and then match the color; if the dye has both hue fluctuations and strong fluctuations, the original sample can be used first. The basic data was first formulated, and then a new wave of dyes with new hue fluctuations and strong fluctuations was replaced. After making a sample, there must be a gap between the sample and the samples. Then correct the sample and correct it. formula. In this way, with the domestic dyes, the first-time success rate of color matching is 85%, and after one or two corrections, the success rate is almost close to 100%. Here, the success rate of color matching refers not only to the sample but also to the correction formula after computer color matching and sample dyeing. After large-scale trial dyeing, the color difference between sample and sample is 4.0 or above; (3) When domestic dyestuffs are purchased, it is better to shop around and try to optimize the quality; it is expected that in the next few years, it will include Hue stability, the use of ultrafiltration membrane desalination, the use of colloids to make the dye particle size up to micron level, improve the color of the dye for the computer will be better and better.

3.2.4.2 Human Factors Affecting Color Change in Dyeing Process

The water quality, steam pressure, and machine tools that have influenced the color in the past have been effectively controlled with pre-staining and automatic degree control. Accurate dyeing material weighing, application of automatic drip system, thereby greatly reducing the color of the system error, online monitoring equipment so that the quality of production is effectively monitored.

4 Examples of color system management

Our factory has more successful examples in such areas as military demand products, blended dye shade control, optimized low cost dye combination, and fluorescence quality check.

(1) The quality requirements of munitions are quite strict. First, this system of color management is decomposed into many control links to perform on-site color management. The control indicators for each aspect of color management are controlled by computers. Specifically, raw materials and proportions are not controlled by color and water quality. Controlled, dye acceptance, pre-processing without color control, blending ratio and color control, spinning and color control, weaving and color control and other indicators of color sampling into the computer, control after finishing, that is shrunk and Color control, softness and color control, carbonization and weeding and color control, steam setting and color control, electrothermal wet and color control, quality monitoring and color control.

Before 1987, it was entirely artificially controlled. By 1987, it had introduced a computer color matching instrument and reached an agreement with the Institute of Military Command of the General Logistics Department. Both sides used the same color measuring instrument to achieve quality control. Each batch of data has a color value that is military necessity. The Ministry recognized (with samples submitted together) that there was a data dialogue between the two parties and that there had never been a quality dispute. In addition, with 555 color difference subdivision method, batch delivery and delivery, sent to different garment factory processing, so that the clothing parts of the color have better uniformity and consistency. No color difference has ever occurred.

(2) Example 2 is a quality check of fluorescence

Kunshan Home Garment Factory is a joint-venture unit, and there are a number of garments exported to Japan. Japanese customers said that the batch of fabrics is not enough for the return of fluorescent light, and they have to make claims. The situation is urgent. After testing Japan, there was no fluorescence. The garment factory took the test data and the Japanese customer theory. The Japanese customers recognized it at first glance. This solves the big problem.

(3) Mixing Dye Light Control Example

A dye factory has produced a red reactive dye because the color light is too blue and users are not welcome. It is proposed whether a yellow dye can be added to match a dye. Use the color meter and color matching function to control the chromaticity of the entire dye, test and control the whiteness of each coloring stage, and test the color difference and rating of the fading. In the end, I put together an ideal red dye.

(4) Choose different dye color matching groups to save costs under similar quality conditions. Due to the fast color measurement by computer, it is possible to select the lowest cost formula among many dyes. According to the output of our factory, in the two years, due to the preference of color matching, more than 600,000 yuan will be saved, which is equivalent to import. Four times the cost of the computer color matching instrument (according to more than 3 yuan RMB to 1 US dollar purchase price in 1985), the economic benefits are significant. In short, we have tasted some sweetness in color management and modern instrumentation.