Research On The Mercerizing Treatment And Blending Of Softwood Pulp For Air Filter Paper

The problem of poor filter paper permeability can be solved by controlled the beating degree or screened the fines,in view of the different requirements for the different filter paper to the pulp used.However,some special filter paperboard with high porosity and low resistance cannot be satisfied by controlled the beating quality and screened the fines.It needs to use some or all of the mercerizing pulp with fiber waviness and high resilience.In this paper,the fiber analysis and fiber parameter morphology under different treatment temperature,time and alkali concentration on the physical properties of filter paper will be explored by their strengthening effect on unbleached sulfate softwood pulp.Meanwhile,the optimal ratio will be obtained and the influence of softwood pulp and synthetic fiber blending on the filtration accuracy of air filter paper will be further explored.The effects of the three factors on the polymerization degree of pulp will be discussed.The results indicated that the polymerization degree of pulp reached the maximum value when the treatment temperature was 75?,the treatment time was 60 minutes and the alkali concentration was 5 mol/L.With the long mercerization time,high temperature,and large alkali concentration,the pulp yield decreased.With the progress of mercerization treatment conditions,the length of fiber decreased inordinately,while the crimp index and the kink index increased in different degrees.Moreover,the mechanism of mercerization changed the shape parameters of fiber.As a result,the effect of treatment conditions on the performance of filter paper,in a sense,depends on the shape parameters of fiber.The papermaking conditions of mercerizing filter paper were optimized by multi index orthogonal experiment,and they were tested by range analysis,variance analysis and SSR.The optimum combination of filter paper with high permeability was determined as NaOH concentration of 5 mol/L,treatment time of 60 min and treatment temperature of 50?.The results manifested that in the blending air filter paper with bleached sulfate softwood mercerizing pulp and bleached sulfate softwood pulp,the dust-holding capacity of filter paper was up to 61 g/m2 when the amount of coniferous wood pulp was 30%and the amount of mercerized wood pulp was 70%.With the increase of pressure,the dust-holding capacity of filter paper decreased slightly compared with the same period of last year.The air permeability was up to 906 L/m2.s,and the initial filtration resistance decreased to 39.25 pa.The results showed that in the blending air filter paper with beating bleached sulfate softwood mercerizing pulp and bleached sulfate softwood pulp,the dust-holding capacity of filter paper was up to 66 g/m2 when the amount of polyester fiber was 15%,the amount of mercerized wood pulp was 85%.With the increase of pressure,the dust-holding capacity of filter paper with the addition amount of corresponding polyester fiber decreased sharply compared with the same period of last year.The air permeability was trending quadratic function,and the initial filtration resistance decreased to 47.27 Pa,when the polyester fiber dosage was 15%.The dust-holding capacity of filter paper was affected by porosity and pore size distribution jointly.When the pore size distribution was similar,the porosity affected the dust-holding capacity of the filter paper.The dust-holding capacity of filter paper would be higher as the porosity increased.When the porosity was similar,the pore size distribution of the filter paper affected the dust-holding capacity of filter paper.