**2.1. Dispersing process**

Water-based pigment systems are environment-friendly pathways. Pigments are dispersed into water with the aid of auxiliaries, such as dispersants, emulsifiers, anti-setting agents, etc. Water-based pigment has been widely applied in coloration for textiles, paints, architec‐ ture, wood and so on [8,9]. But the unmodified pigment dispersion that contains pigments with large particle size is unstable and also suffers from the problems as precipitation and floating color. And then the color, fastness, handle and uniformity of the fabrics dyed with

Ultra-fine modified pigment (UMP) is referred to nanometer or micrometer pigment particle by physical and/or chemical modifications in a composite disperse system with attaching functional groups for pigment dispersion. These functional groups often have contribution to appear the vivid color for the chromophoric groups in the pigment particle by selectively reflecting and absorbing certain wavelengths of visible light [6]. The UMP dispersion usual‐ ly shows relative stability and higher color strength (K/S value) which closely approaches to that of dyes [10]. When UMP is used to color, the finely divided, insoluble particle remains throughout the coloration process [1]. Without the binder or less the amount of binder add‐ ed in printing paste, the good handle will be achieved. And the better fastness is attained with the stronger attraction between the UMP and the fiber [10,11]. The UMP systems are divided into nonionic pigment dispersion, anionic pigment dispersion and cationic pigment dispersion according to the charged particles. Compared to the nonionic pigment disper‐ sion, the pigment dispersion with ionic dispersant may produce the stronger combining

The cationic disperser has been widely used in many fields. It had been reported in Japanese patents that cationic disperser was applied in electrodeposits coat. Being prepared with cati‐ onic disperser, the cationic pigment dispersion is able to decrease the migration of the pig‐ ment, and favorable dyeing deepness and color fastness are also obtained when such pigment is applied to pretreated cotton fabric and terylene-cotton fabric in pad dyeing [14]. The cationic surfactant is grafted onto the acrylic acid copolymer to attain disperser which is then applied to the anthraquinone pigment to prepare ink for ink-jet printing on paper [15]. In addition, there are many applications of cationic disperser in other fields, such as paper‐ making, image thermomigration, ink-jet printing paper, inorganic nano-scale powder and preparing hydrophilic ethylene copolymer dispersion. Moreover, pigment dyeing by ex‐ haust process is possible by imparting substantivity with cationic reagents to induce the nec‐ essary affinity between pigments and fibers. The chemical modification of fiber with cationic

In this chapter, the preparation of UMP, such as dispersing process, grinding process, ultra‐ sonic wave process, microencapsulated process and microfluidics process are all summar‐ ized. And the particle size, disperse stability, Zeta potential and color properties, which are used to characterize the UMP are also analyzed. Moreover, the dyeing properties of UMP on

Different from dyes, UMPs are totally insoluble in organic mediums due to its strong in‐ termolecular aggregation, and they are required to be finely ground and dispersed in an

reagents has been carried out to improve the dyeing properties [1,16].

cotton, silk, wool and acrylic yarns are mainly reviewed.

the unmodified pigment dispersion are influenced.

power to the fabric [12,13].

78 Eco-Friendly Textile Dyeing and Finishing

**2. Preparation of UMP**
