| Tissue paper is one of the necessities direct contact with human skin in daily life.Compared with the white papers that are more common in the market,in recent years,the natural color tissue papers based on resource intensification and environmental protection are showing a rapid development momentum.However,the latter has a clear gap with the former in terms of the product quality,especially the softness,and has become one of the main bottlenecks restricting its development.Starting from the quality control of the pulp for natural color tissue paper,eucalyptus and Simao pine were used as the raw materials,and sulphate cooking was combined with alkaline-oxyg en delignification to obtain the natural color pulps.The tissue paper made from them was soft colors natural,and offered superior softness.At the same time,the effects of long and short fiber ratio,slurry beating degree and softener on paper performance were discussed.Through the above experiments,the understanding of the intrinsic relationship between them has become clear.The removal of lignin from the pulp had a positive effect on improving the softness of the paper.Through the evaluation of the sheets,handmade from the pulps separately by kraft cooking,alkali-oxygen delignification also bleaching by chlorine dioxide,showed that: 1)the softness value of the paper decreased fastly then increased slightly with the decrease of lignin content in the pulps,and the best date occurred at the lignin content of 1.73% for Simao pine pulp and of 1.22% for eucalyptus pulp.2)The effect of wet pressing on the softness of the paper was very obvious,as exhibited in the big drop of the softness value from 160 mN to 71 mN along with from 0 MPa to0.6 MPa for the oxygen 2 pulp sheet;3)From the XRD spectrum analysis of the pulp,the crystallinity of the bleached pulp was higher than that of the alkali-oxygen pulp,resulting in an increase in the softness value of its sheet.The orthogonal experimental design method was used to examine the correlation between paper performance and the beating degrees of eucalyptus pulp and Simao pine pulp also their fiber ratios.The results showed that the effect in improving the sheet softness was weakened in turn by: the ratio of long and short fibers,the beating degree of Simao pine pulp and the beating degree of eucalyptus pulp,and the best softness of the sheet was obtained in the 70% of eucalyptus pulp,34 °SR and 32.6 °SR for the Simao pine pulp and the eucalyptus pulp,tespectively.Additionally,the dynamic water filtration performance of Simao pine pulp was obviously affected by the beating degree because of the outstanding increased proportion of fine fiber components,and that of eucalyptus pulp was not significantly reduced due to the increase of beating degree.The alkali-oxygen pulp was evaluated for the influence of the softener on their sheet performance.1)Both the in-slurry addition and the surface coating of the softener has a positive effect on the softness of the paper,and the softening effect of the latter was better than that of the former,and their lowest softness values were 98 mN and 108 mN in an amounts of 0.4% and 0.75%,respectively.2)The dry tensile index of the paper decreased with the addition of softener,while the wet tensile index showed an opposite trend.3)It can be seen from the SEM image that a particulate-like substance adhered to the sheets in the case of the surface coating,being soft to the touch. |
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