| With the global scarcity of wood material, researchers and papermakers pay more attention to using recycled paper and high yield pulp (HYP). The poplar alkaline hydrogen peroxide mechanical pulp (APMP) fiber, which had been studied mainly in this paper, has the properties such as short fiber length, poor strength and bad retention in papermaking.Firstly, the effects of strength additives, such as poly-ethyleneimine (PEI), poly- amideamine-epichlorohydrin (PAE), cationic starch (CS) and amphoteric starch (AS), on the physical and optical properties of hand sheet were investigated. The results showed that adding PEI, PAE and AS all had good strengthening improvement. When referring to the strength enhancement of hand sheet, AS had better effect than CS, and PAE had better effect than PEI. When the dosage of AS was 1.0%, tearing index, tensile index and bursting index of the hand sheet were increased by 7.4%, 12.8% and 7.6% respectively; when the dosage of PAE was 1.0%, tensile index and bursting index were increased by 9.5%, 14.9% and 12.5% respectively.Secondly, the effects of different retention and drainage systems including single, dual and ternary retention system on the drainage and retention properties of APMP hand sheet were explored. The effects of highly cationic polymer like PEI and cationic guar gum (CGG) on the properties of APMP hand sheet were also discussed. The results showed that adding W/O CPAM with higher cationic charge density and molecular weight had better benefits than adding W/W CPAM on drainage and retention properties of APMP. Adding modified PEI or CGG as anionic trash catcher (ATC) could improve the retention and drainage rate of APMP in CPAM or CPAM/bentonite system. When adding 0.02% dosage of PEI,the drainage and retention rate were increased by 16.0% and 1.9% respectively as compared to the control with 0.03% dosage of W/W CPAM; the drainage and retention rate were increased by 28.6% and 3.0% respectively as compared to the control with 0.03% dosage of W/W CPAM and 0.3% dosage of bentonite.Then, the effect of highly cationic polymers as ATC on the AKD neutral sizing in APMP papermaking was explored. The result showed that adding modified PEI or CGG as ATC had remarkable improvement of sizing efficiency of APMP in CPAM single system. When adding 0.02% dosage of PEI and 0.03% dosage of CPAM, the sizing degree of before and after curing were 38s and 47s respectively, increased by 50.0% and 38.9% respectively as compared to control with 0.03% dosage of CPAM. When adding 0.05% dosage of CGG and 0.03% dosage of CPAM, the sizing degree of before and after curing were 37s and 44s respectively, increased by 41.7% and 22.2% respectively as compared to control with 0.03% dosage of CPAM.In order to achieve the purpose of enhancing the hand sheet performance like optical properties and physical properties, the effects of inorganic mineral fiber (IMF) such as mineral composite fiber (MCF) and calcium sulfate whiskers (CSW) compounding with fiber or traditional filler like ground calcium carbonate (GCC) and talc on the hand sheet performance were compared so as to decide the preferable dosage of IMF in APMP hand sheet. The results showed that when adding MCF, CSW, GCC and silica into APMP fiber respectively, the ash content and optical properties were obviously improved; adding CSW and silica could remarkably improve the bulkiness of hand sheet. When MCF was compounded with traditional filler, the ash content and optical properties such as whiteness, opacity and light scattering coefficient (LSC); the optimal dosage of adding MCF into APMP fiber was from 4% to 10%. When silica was compounded with traditional filler, the ash content and optical properties were also obviously improved.
|
PDF Full Text Request