Study On Color Mixing Law And Color Prediction Model For Interwoven Fabrics

During the woven fabric development, the interweaving of colored yarns of several colors through different weave structures and weaving processes can enable fabrics to gain rich color effects. Interwoven technology was mainly used in the color design of yarn-dyed check fabrics and jacquard fabrics in the past. This study is committed to applying interwoven technology to the production and development of chromatic clothing or household textile fabrics so that it can replace dyeing process of some fabrics. The main bottleneck restricting its promotion and use is exact control and accurate prediction of color. In order to study the mechanism and laws of colored yarn interweaving, solve problems such as a limited number of colors, inconsistency between the expected color and actual color in product design, traditional color matching process of fabric sample is time-consuming and laboursome, this study takes dope dyed polyester filament yarn and its interwoven fabrics for example and conducts researches on color evaluation of interwoven color mixing fabrics, color prediction model building, analysis of interwoven color mixing laws and color measurement and matching system development so as to lay a theoretical foundation and provide practical references for the further promotion and application of interwoven color mixing technology and then greatly promote the development of water saving or waterless dyeing textiles and realize emission reduction of printing and dyeing wastewater and carbon dioxide.(1) In order to explore the most suitable color evaluation method for colored yarn and interwoven color mixing fabrics and lay a foundation for color prediction model building and color measurement and matching system research, this paper compares the applicability and limitations of different color measurement methods and equipment used in color evaluation of different color samples, and proposes color measurement methods for different forms of colored yarns and color samples of interwoven color mixing fabrics. In this research, visual method, spectrophotometric method and digital image color measurement method are applied to color evaluation of paper color card and color samples of dyed fabrics and interwoven color mixing fabrics at the same time. Parallel comparison shows that: as a result of limitations of principle, digital image color measurement system has certain color gamut defects; but visual evaluation and analysis show that it more corresponds to the visual observation result; calibrated digital image color measurement system and spectrophotometric color measurement system can obtain consistent color evaluation results(?E00 = 0.79) when they are used for color measurement of paper color card; but color differences will emerge when they are used for color evaluation of dyed fabrics without flat surface(?E00 = 2.19); color differences further increase when they are used for color evaluation of interwoven mixing fabrics(?E00 = 3.25). In addition, color difference is related to the fine degree and folded layers in tests. As a conclusion, digital image color measurement system is more suitable for color evaluation of large-batch and non-planar yarn or fabric samples; but in the study of color measurement and matching, spectrophotometric method used to measure the reflectivity spectrum of color samples is recommended.(2) In order to build more accurate interwoven color prediction model, this study chooses dope dyed polyester filament interwoven fabric as example, constructs modified geometric structure models of single and double weft interwoven fabrics, proposes the theoretical calculation method of surface dyed yarn and gap coverage rate of interwoven color mixing fabrics, puts forward the theoretical calculation method of flattening coefficient of yarns in the geometric structure model through iteration and approximation calculation between actual and theoretical dyed yarn coverage rates, and conducts verification with multiple models. Based on the colorimetry theory and Kubelka-Munk theory and spectral reflectance data of fabrics measured practically, a new model with empirical coefficient and intermediate function, which can be applied to the color prediction of interwoven color mixing fabrics, is proposed and the empirical coefficient is determined with Newton iterative algorithm. Interwoven fabrics with different specifications and thread counts are made for model verification. Statistics of color difference between predicted and measured color values shows that, the new model has different prediction accuracy in different wavelength ranges, but the overall prediction accuracy is much higher than existing models and methods.(3) In order to obtain the optimal primary color combination, complementary colors and chromaticity laws of interwoven color mixing yarn, this paper selects 6 yarns of primary color most approximate to the ideal primary color and designs and makes 288 pieces of interwoven fabrics of primary color yarn and conducts discussions from the perspective of color gamut distribution. The distribution law of actual colors in CIE1976 chromaticity diagram shows that, among primary color combinations such as RGB, CMY, NCS and RGBCMY, only RGBCMY primary color combination can obtain a relatively complete and large color gamut without adding excessive primary colors. On CIE1976 chromaticity diagram, color coordinates are basically distributed on the connected line of primary color coordinates and their specific positions are determined by the coverage rate of dyed yarn on the fabric surface. Through the study on interwoven color mixing law, this paper proposes the selecting principle of primary color, summarizes complementary color laws of interwoven color mixing, and obtains theoretical and practical relational expressions between position coefficient and dyed yarn coverage rate in CIE 1976 chromaticity diagram and those between lightness difference coefficient and dyed yarn coverage rate through fitting analysis on measured data.(4) Based on matrix calculation and VB software development environment, the new model is applied to color prediction and matching practice of interwoven color mixing fabrics. Therefore, the method for conversion among dyed yarn coverage rate on the fabric surface and weave structure, thread count and linear density is obtained. In combination with color setting of weft and warp, color measurement and matching system of interwoven color mixing fabrics is formed. The system can forecast the color of dyed yarn mixture accurately, obtain the reasonable dyed yarn coverage rate on the fabric surface under a given weft and yarn combination through backward derivation based on the final color of fabrics, and finally obtain the warp and weft color of the corresponding weft and warp coverage rate, thread count and weave structure.At present, systematic research of interwoven color mixing laws and prediction accuracy of interwoven color prediction models still have many deficiencies; mature theoretical system and effective color measurement and matching method haven’t been built yet; among literatures and works available in this thesis, research on yarn color mixing law from colorimetric perspective is still blank. Benefited from empirical coefficient and intermediate function, the color prediction model of interwoven color mixing fabrics put forward in this study based on the modified fabric geometric structure model has certain correction function for dyed yarn coverage rate on the fabric surface and morphological characteristics of warp/weft raw materials. The prediction accuracy and applicability of the new model are much higher than previous interwoven color prediction models with fixed forms. The optimal primary color combination and color mixing law obtained based on reliable color evaluation method and color gamut distribution analysis have important guiding significance for the design and development of full color interwoven fabrics. The application practice of the new model of color prediction provides valuable algorithm and program and is a new research area with the combination of textile engineering, colorimetry theory and computer technology.