Research On The Technology Of Pigment-dispersing For Photoresist

Color filter is one of the key components of the Liquid crystal display, it needs performances of high-transmittivity, thermal stability and lightfastness and so on. The form of organic pigment which is used for colorant affects the performance of luster, pigmentation, envelop, transparency and tone. Therefore, organic pigment must to be fine and symmetrical in the photoresist.Ultrafine organic pigment has a high surface energy, it is easy to form bulky particle by mutual attraction of particles that leading the system instability, and the pigment is not suitable for photoresist in color filters. The purpose of this research is to disperse and stabilize the red organic pigment P.R.177 so that it can be used for modulation the photoresist.Pigment, dispersant, dispersed resin and dispersing agent are needed in the pigment dispersed system. Impacting of dispersants and resins on the particle size and stability of P.R.177 pigment dispersed system was discussed, the type of dispersants and resins should be compatible with the other components of photoresist. The particle size showed that the components of the system have great effect on the dispersion and stability of pigment. In the same condition, the amount of dispersant and resin has a best value, too small or too much will cause fiocculation of the system, resulting in instable system.Secondly, different pigment dispersed systems need different decentralization and rubbing processes. The impacting of dispersion process on P.R.177 pigment dispersed system also discussed and the results show that the particle size can not reduce along with the increasing of rotate speed, but there is a best range of the rotate speed, too fast will made the particle size augment. And it is can not judge the effect of rubbing to the pigment system with time, only if pigment particles own adequate energy can be minimized smaller, so in order to get a stable pigment dispersed system, the appropriate energy input is necessary. So in the same condition, more energy is required for more pigment solution.Finally we got the small particle size, narrow particle size distribution and high stability pigment dispersed system after a large number of theory analysises and experiments. The photoresist have better stability and chroma which brewage by this pigment dispersed system. The photoresist was spin coated on glass substrate, the red pels on the color filter which owns good performance of chroma and optics through the semiconductor prosess such as exposal and develop.