Preparation And Dyeing Properties Of Waterborne Dispersions Of Ultrafine Carbon Black Particles

Carbon black (CB) is one of the most important chemical materials. It is widely used in rubber, plastics, printing ink, coating and the other fields. The dispersing performances of CB particles were discussed and two preparing methods of waterborne dispersions of ultrafine CB particles were compared. The performances and dyeing properties of waterborne dispersions were also analyzed. And the effects of cotton modified with a cationic reagent on the dyeing properties of ultrafine CB dispersions by an exhaustion process were investigated in this paper.From the point of the action of three parts (dispersing media, addition and CB particles) in CB dispersions, the dispersing performances of CB particles were discussed. The results showed that the dispersing effect was better when CB particles were dispersed in media either with lower polar which the dielectric constantεof the liquid is at the range of 4.9～13.3 or with smaller sedimentation factor C which C is below 1.043. Addition would influence CB particles to disperse in media. Moreover the CB particle size became larger with the extent of oxidation because the surface structure of CB was changed by the liquid oxidation.The effects of small molecular dispersants, polymer dispersants (sodium carboxymethyl cellulose (CMC) and poly (vinyl pyrrolidone) (PVP)) on dispersing CB particles directly were studied. And the mixtures of two dispersants used to disperse were also discussed. The results showed that anionic dispersant with small molecular weight could disperse CB particles effectively, and among these sodium methylenedinaphthalene disulphonate (NNO) was the most effective agent in dispersing CB particles. CMC with different viscosity was able to affect the degree of dispersing CB particles in aqueous media. CB particle size obviously decreased with increasing ultrasonic time and arrived at minimum about 160nm. Oxidation with hydrogen peroxide was beneficial to preparing for waterborne ultrafine carbon black dispersion. The particle size and the absolute value of Zeta potential of CB particles dispersed by PVP decreased with increasing ultrasonic time. However oxidation with hydrogen peroxide was not in favor of dispersing CB particles. It seemed that the mixture of nonionic and anionic dispersant had not sympathetic effect on dispersing CB particles. The CB dispersion properties dispersed by the mixture of CMC and NNO were superior when the dispersion was oxidized with hydrogen peroxide at high temperature. And the dispersing efficiency of PVP can be more effectively promoted by adding NNO than polyoxyethylenated octylphenol (Tx).The dispersion properties were also discussed when CB particles were encapsulated by CMC or PVP. The results showed that the amount of nonsolvent affected the CB particle size. The particle size and the absolute value of Zeta potential of CMC-encapsulated CB particles were larger and the dispersion had better centrifugal stability. However when the amount of initiator was larger than 1.6wt%, the CB particle size was obviously increased which CB particles was covered by PVP. Moreover, when CB dispersions were treated by ultrasonic, the particle size and Zeta potential of PVP-encapsulated CB particles were similar to those of PVP-adsorbed, but the former had better centrifugal stability. Nevertheless the PVP-encapsulated layer can be destroyed by long-time ultrasonic treatment and the dispersed CB particles can congregate with each other again.The properties of waterborne dispersions of ultrafine CB particles were analyzed. The results showed that the apparent viscosity of dispersions increased with the increasing amount of NNO and the rheological property of CB dispersions was pseudo-plastic behavior which the apparent viscosity of system became thicker with the increasing shear rate. And the apparent viscosity increased with the increasing amount of CB particles. When the amount of CB particles is below 5 wt %, the apparent viscosity of CB dispersions became thicker with the increasing shear rate. While the amount of CB particles is 10 wt %, the apparent viscosity of CB dispersions became thinner with the increasing shear rate. The waterborne dispersions of ultrafine CB particles had good centrifugal stability. CB dispersions with various particles size D₀ can achieve by centrifugal method, which the minimum D₀ was 36.1nm. All of the CB dispersions had good stability under gravity at 25℃and 80℃. CB dispersions which D₀ was 90.5nm had good re-dispersing properties.The dyeing properties of waterborne dispersions of ultrafine CB particles were investigated. The results showed that the various dispersants affected the K/S value of dyed cotton fabrics. Among these cotton fabrics dyed with sodium dibutylnaphthalene sulphonate (BX) dispersions had the highest K/S value. CB uptake and colour yield on cotton obviously decreased with the increasing amount of dispersant NNO or Tx used in waterborne dispersions. The CB particle size has a little effect on the dyeing properties of cotton fabrics. CB uptake increased with the increasing amount of CB particles, however it decreased when the amount of CB particles was above 8%owf. The curves of the color strength changed by the amount of CB particles were similar to the Langmuir type. The K/S value of dyed fabrics arrived at the maximum when the amount of CB particles was 10%owf, while the K/S value of fabrics after washed with soap reached to the maximum when CB particles was 4%owf. Adding electrolyte NaCl to CB dispersions favored the CB particles adsorption. Adding binder can obviously improve the color strength of dyed fabrics, but can not improve the rubbing colorfastness.On the basis of cotton fabrics modified with a cationic reagent, the dyeing properties of CB dispersions were discussed. The results showed that the various dispersants also affected the dyeing properties of cationised cotton fabrics. Among these the cationised cotton dyed with BX or Tx dispersions had higher K/S value. CB uptake and the K/S value of cationised cotton obviously decreased with the increasing amount of dispersants NNO or Tx. However the CB particle size affected the dyeing properties of cationised cotton obviously. CB uptake on cationised cotton decreased with the increasing amount of CB particles. When the CB concentration was 2%owf,. the largest color strength of cationised cotton was obtained. Adding electrolyte to CB dispersions had little effect on the dyeing properties of cationised cotton. And it was feasible to dye without electrolyte. Adding binder reduced the K/S value of cationised cotton, while it improved the dryfastness and wetfastness properties.The mechanism of cationised cotton dyed by an exhaustion process using waterborne ultrafine CB dispersions was investigated. Cotton modified with a cationic reagent enhanced the dyeing properties of waterborne CB dispersions and the improvement of cotton dyed by Tx dispersions was the best of all. There were higher affinity existed between ultrafine CB particles and cationised cotton. CB particles can quickly adsorb on the surface of cationised cotton fibers within 5 mins and diffuse into the inner pores and cracks on the surface layer of cationised cotton step by step.