Research On Chemical Synthesis And Mechanism Of Bulk Additives For Light Weight Printing Paper

Light weight printing paper is a kind of bulky paper which has soft colors and good printability. It is accepted by typographers and readers since it was brought in China in late 1990's, and it will be widely used in printing books. The main qualifications of light weight printing paper are high bulk and good printability. There are many ways to increase bulkness, such as using high yield pulp, adjust beating process, improve press process and using special fillings and chemical additives which will increase bulkness. The popular way used by most of paper plants is to use high yield pulp, and some paper plants abroad use 100% high yield pulp to produce this kind of paper. Because our country is short of timber resources, we need to use ways other than using high percentage of wood pulp.Researchers abroad using chemical additives to increase bulkness of paper. The mechanism of increase of bulkness is to provide hydrophobic nature to the surface of cellulose, and reduce combination between celluloses. In this paper, a way to increase bulkness of paper is studied. In the process of paper manufacture, lignin-phenol-formaldehyde resin was added into the pulp as well as wood flour and swell soil. Technological conditions of synthetic reaction of LPF and effects of each compound on property of paper were studied in this paper. Proportion of each compound was studied by orthogonal experiment, and effect of pore structure on the paper to printability was also studied.Firstly, the technological condition of synthetic reaction of LPF is as follows: the mole ratio of formaldehyde and phenol is 1.4:1, and the mole ratio of sodium hydroxide and phenol is 0.3:1, and the time is 2.5h, and the temperature is 85℃, and the proportion of synthetic lignosulfonate used to replace of phenol is 30%. The solid content of LPF is about 30.5%, and the viscosity is about 495mPa·s, and the contents of free phenol and formaldehyde is 4.6% and 0.21% respectively. It has miscibility with water.Secondly, effects of LPF, wood flour and swell soil on properties of paper were studied. As results shows, bulkness, breaking length, burst index and smoothness of paper improved with the mount of LPF used increased, but ability of ink absorption decreased. Bulkness and ability of ink absorption of paper increased with the amount of wood flour increased, but breaking length, burst index and smoothness of paper decreased with the amount of wood flour increased. Smoothness of paper decreased,and bulkness, breaking length, burst index and ability of ink absorption of paper increased with the amount of swell soil increased.Thirdly, mixing ratio of LPF,wood flour and swell soil was determined by orthogonal test. Paper properties were better when the dosage of LPF,wood flour and swell soil were 2.0%,25% and 5%.Finely, the effects of pore structure of paper on printability were also studied. In this paper, effects of porosity on smoothness and ink absorption ability were discussed. As the results showed, smoothness increased and ink absorption ability decreased with the porosity increased.