Organic Pigment Microcapsules In Situ Preparation And Pigment Printing

Organic pigment is widely used in inks, dyeing, printing and other fields because of its outstanding properties. However, organic pigment is hard to be wetted and dispersed in water media and on fabric surface due to their low polarity and easily aggregation. Thus, massive of adhesive should be used in pigment printing, which inevitably results in the contradiction between the handle and the color fastness. An effective and oriented microencapsulating of pigment particles with adhesive polymer was regarded as one of the most effective way to avoid this contradiction.In this paper, copper phthalocyanine blue (PB) particles were successfully encapsulated by styrene-acrylic polymer via in situ suspension polymerization and in situ miniemulsion polymerization, respectively. And a series of microencapsulated pigments with controllable morphology, particles size and size distribution were successfully obtained. After that, the application of these microencapsulated pigments on pigment printing of cotton and silk fabrics was studied. The result showed that the combination between pigment microencapsulation and fabric was excellent, and the handle of printing textile was acceptable.Firstly, the distribution of organic pigment-PB in water/monomer phases and the dispersion of PB particles in monomer were investigated. It was found that PB particles are always dispersed in the monomer phase steadily and homogeneously, which implies that the encapsulation of PB particles of adhesive polymer via non-homogeneous polymerization such as miniemulsion polymerization and suspension polymerization is completely possible.Secondly, the microencapsulating of PB particles via miniemulsion polymerization was studied. The influences of polymerization recipe and technology on the polymerization stability, microencapsulation morphology were systematically investigated. It was found that PB takes an inhibiting role in polymerization, and generally brings a worse of particles size distribution. Microencapsulation morphology characterized by TEM and particles size distribution measured by DLS showed that the encapsulation of PB with soft polymer, such as butyl acrylate, is obviously better than that with hard polymer, such as styrene.Thirdly, submicron copper phthalocyanine microencapsulation was successfully prepared via in-situ micro-suspension polymerization. The reaction system stability during polymerization was monitored and the microencapsulation morphology was characterized by OM, SEM and TEM. It was found that the presence of plentiful pigment particles always lead to the deterioration of polymerization stability and microencapsulation morphology. However, this deterioration can be effectively inhibited by pre-polymerization of the pigment monomer dispersion since pre-polymerization can improve the viscosity of monomer drops. After that, the influences of polymerization recipe and technology on the microencapsulation particles size were studied. It was found that the particles size and size distribution can be adjusted in a larger range through changing the amount of disperse and shearing strength. Thus a series of"guava-like"organic pigment microencapsulations with regularly spherality, better polymerization stability and controllable morphology, particles size and size distribution can be successfully prepared.Finally, the above two kinds of microencapsulations were applied to the pigment printing of cotton and silk, and the effects of microencapsulation type, distemper constituted form, encapsulating polymer property and printing technology on the printing qualities were investigated. It was found that both the encapsulating polymer property and the baking technology play important roles in improving printing quality due to the segmental mobility and flexibility of encapsulating polymer. The appropriate encapsulating polymer layer is the copolymer of butyl acrylate and fractional rigid monomer, and the appropriate baking temperature and time is 140 oC and 5 min. After that, it was further found that the microencapsulation prepared by in situ suspension polymerization presented unsatisfactory performance of pigment printing because of its larger particles size. On the contrary, the other microencapsulation which was prepared via in situ miniemulsion polymerization was found facilitate to be used in pigment printing. Comparing with the traditional printed fabric, the K/S value, the handle, the dry and wet rubbing fastness of printed fabric treated by microencapsulated pigments were better than the former, implying the present of polymeric layer on the pigment particles could remarkably improve the dispersion of pigment particles on fabric surface and simultaneously the binding force of pigment particles with fabric.In a word, this paper shows that there are many advantages of organic pigment microencapsulation on the pigment printing of cotton and silk, and the microencapsulation of pigment is one of the effectively way to obtain excellent fabric with better handle and rubbing fastness.