| China is the biggest country at neutral ball-point making pen,but the key technologies of neutral ink R & D has been monopolized by foreign enterprises.Independent R & D of excellent performance neutral ink is the way to solve the problem,to get rid of the rely on imports.To start with,the paper summarize the definition of gel ink,technology reflected and status of development in the world,and point out the importance of stability to gel ink writing performance.This paper research stability to gel ink at variety and content of carbon black.The result shows that, the particle size of gel ink decreases with the decrease of specific surface area of the carbon black, increases with the increase of carbon black content.The apparent viscosity of gel ink increased with the increase of carbon black content, and decreases with the rise of temperature, which are not necessarily bound up with specific surface area. Small specific surface area of carbon black make particle size of gel ink smaller, but high BDP value make stability of gel ink worse.So we consider BDP value and other indicators in choice of carbon black.In the gel ink, dispersion resin, adsorbed effectively on the surface of carbon black pigment, can improve the pigment’s dispersion stability. The effect of sanding time and addition of styrene-acrylic copolymer resin on the stability of gel ink was studied in this article. Rosin-Rammler distribution function, commonly used for description of particle size distribution, was fitted.Then the relationship between the rheological property of gel ink and, the index n and The constant De, indicating particle size distribution, was obtained. And the stability of prepared gel ink was tested. It turns out that the particle size of gel ink decreased with the increase in sanding time but when the time was more than 120 min, the size maintained constant, and the distribution of particle size fitted the function of Rosin-Rammler, especially speaking, the yield stress reduce with the raise of n value or the decrease of De value. The fluidity of ink became good, when the distribution of particle size become narrow. Meanwhile the apparent viscosity of gel ink increased with the increase in addition of styrene-acrylic copolymer resin and decreased with the increase in temperature. Thus the whole system’s stability became worse and worse.In the gel ink, surfactant made the dispersion stabilize, because of its wetting in the surface of carbon black and its capacity of facilitating agglomerates break. In the work, two kinds of surfactant were selected in the preparation of ink, one was dioctyl sulfosuccinate sodium salt(4187) belonging to anionic surfactant, the other was alkyl phenol polyoxyethylene ether (OP-10)belonging to nonionic surfactant. In the research, only one and the composite effect of 4187 and OP-10 was studied. The results shows that when only one surfactant was added, the size of carbon black and apparent viscosity first decreased and then increased with the increase of surfactant; but the concoction was added, the apparent viscosity, the size and thixotropic index climbed up and then declined with the increase of HLB value of surfactant, meanwhile after heating, the apparent viscosity rised and the ink became more stablizable. |
