The lithium ester is an organic material located at the end of the gel pen for sealing the neutral ink in the ink tube. The conventional oily ballpoint pen can be filled with no lithium ester, because the oily ballpoint pen ink is a hardly volatile substance, and there is substantially no thickening or drying of the ink due to solvent evaporation. The neutral ink infused by the gel pen is mostly a water-low alcohol suspension of the pigment. When exposed to dry air for a long time, the solvent volatilizes easily, which causes the ink to become sticky and cannot be written normally. In addition, the low viscosity The neutral ink will flow back in the ink tube, and the lithium ester also acts to prevent the ink from flowing backward. The lithium-based ester should be incompatible with the neutral ink, the interface is clear, no turbidity occurs, and the ink tube bubbles are easily removed by centrifugation after the pen is loaded. Most of the lithium-based esters are polyorganosiloxanes, which are not miscible with water, are oily, have good high and low temperature stability, do not freeze at -20 °C, do not overflow at 80 °C, evaporate, and have excellent mobility with thixotropic properties. Excellent lithium-based esters enable the gel pen to maintain a good moisturizing seal when the temperature changes greatly, preventing the ink from evaporating or backflow. When printing quickly, the sealant can follow up at any time, and the wall is lighter. Until the ink is written completely.
At present, there are many types of gel pens on the market. According to the pen head, there are stainless steel, nickel white copper, lead brass, etc. According to different ball materials, they can be divided into tungsten carbide balls, modified ceramic balls, etc. The structure is different, and it can be a bullet, a gourd head, a needle head, and the like. In recent years, the inner diameter of the neutral refill ink tube has changed greatly, and different ink tubes with inner diameters from 2.0mm to 7.0mm have appeared. The ink volume perfusion of the larger inner diameter ink tube has increased from the original 0.5g/branch to 2.0g/ The length of a single writing is increased from 400-500 m to nearly 2000 m, which puts higher requirements on the ink resistance of the writing head and the storage and follow-up performance of the lithium ester.