Hue And Color Depth Of Fabrics Finished With Nanoporous Coating

The strong reflection of incident light at the surface of polyester and other fibers results in the low dyeing efficiency of the dyes within the fibers,which was the main reason for the low apparent color depth.After construction of nanoporous coating at the fiber surface,the reflectivity would increase,leading to improved efficiency of light penetrating fibers and dye chromogenic rate.This was the most effective means to obtain ultra-dark fabrics.Previous studies showed that nanoporous coatings could be obtained by spinning coating of PMMA/PBA latex premixed with a small amount of ammonium bicarbonate?NH₄HCO₃?.Being inspired by this result,for the first time,such nanaporous-structured coating was applied for the surface finishing of colored flat panel substrates and polyester fiber.The structure of the coatings was controlled by the solid content and the size of particles in the coating solution.The hue and color depth of the coated substrates were studied.The following were concluded:1.After addition of 0.27 mol/L NH₄HCO₃,nanoporous coatings were obtained by spinning coating of PMMA?57 nm?and PBA?84 nm?latex blend.The coatings exhibited good antireflective properties.With the increase of latex concentration,the thickness of the coatings increases linearly,and the maximum antireflective wavelength of the films shifts to a larger wavelength.2.When the particle size of PMMA in the coating solution exhibited unimodal distribution,the transmittance of the coating film changes obviously with the wavelength.The coatings with120 nm and 165 nm thickness were prepared by PMMA with average particle size of 57 nm,and the maximum transmittance of the two coatings were 500 nm and 643 nm,respectively.After being coated with two films,the color depth of red,blue and black flat substrates increased significantly.The hue of the red substrates?maximum absorption wavelength 480-560 nm?changed little by the coating with a thickness of 120 nm.However,the red light of the blue substrates?maximum absorption wavelength 570-670 nm?and the black substrates?maximum absorption wavelength 400-650 nm?were enhanced,resulting in the significant change of hue of these two substabces.The hue of the blue substrates changed little by the coating with a thickness of 165 nm.However,the blue light of the red substrates and the black substrates were enhanced,resulting in the significant change of hue of these two substabces.It was thus concluded that only when the maximum increased transmittance wavelength closely matched the maximum absorption wavelength of the substrates,the colored substrates exhibit good hue reproduction.3.As the mixture of 135nm PMMA with 85 nm PMMA was applied as coating solution,the increased transmittance of the nanoporous coating is alomost constant within the full visble light range.After coating with this film,not only the color depth of red,blue and black substrates increases,but also the hues of these substances were totally reserved.4.When PMMA with unimodal distribution of particle size was used to deepen polyester fabrics,nanoporous films were formed on the surface of the fabric.With the increase of the amount of finishing agent,the coverage of the agent on the surface of the fabric increases,and the depth of the fabrics increases.However,the further increase of the amount of agent,PMMA forms large-sized flocs at the fiber surfaces,which caused strong light scattering and lowered the color depth.The color depth of the fabric would be further improved when the latex blend of135nm PMMA and 85nm PMMA was applied as finishing agent.5.After testing the black polyester fabric deepened by PMMA,it was found that the either the high dosage of additives or the increased proportion of large PMMA in the double-particle additives will cause the enhancement of blue light of the finished fabric,which was consistent with the results found for flat-panel colored substrates.