硼改性微粒硅溶胶助留助滤研究

研究了剪切力和CPAM、阳离子淀粉、硼改性硅溶胶用量对硼改性溶胶与阳离子淀粉或CPAM组成不同助留助滤体系的助留助滤效果的影响；同时研究了硫酸铝用量、pH值及电解质用量对助留助滤效果的影响。研究结果发现：阳离子淀粉／硼改性硅溶胶微粒助留体系的抗剪切能力优于阳离子淀粉一元助留体系。阳离子聚合物／硼改性硅溶胶微粒助留助滤体系的助留助滤效果优于一元助留滤体系，同时大大地改善了纸页的匀度。阳离子淀粉／硼改性硅溶胶微粒助留助滤体系在pH值4～8时，以及在松香施胶体系中硫酸铝用量≤3％时较为适用，该体系抗电解质干扰能力强。

硼改性微粒硅溶胶助留助滤体系的絮聚机理

通过几种絮聚模型-DDJ动态滤水仪法、结合激光粒度仪研究絮团大小的变化以及纸张匀度的比较,发现硼改性微粒硅溶胶对浆料絮聚机理是先加入阳离子聚合物,使纤维与细小组分絮聚成较大的絮聚体,初始絮聚体受到高剪切力作用,被打散成小碎块,从而为带负电荷的硼改性微粒硅溶胶暴露出更多的链圈和链尾。硼改性微粒硅溶胶就在这些吸附于不同浆料粒子上的链圈和链尾之间,靠静电中和及与聚合物中非带电段的吸附作用,使近距离的细小碎块桥联而发生重新絮聚,形成较初始絮聚体更小、更均一、更致密的絮团网络。结果大幅度提高了细小纤维和填料的留着率,改善了浆料的滤水性。同时又获得了良好匀度的纸页。

硼改性微粒硅溶胶的超滤浓缩及稳定性

选用超滤法浓缩硼改性微粒硅溶胶，在室温、操作压力3．5kPa的条件下、选用截留相对分子质量为10000的醋酸纤维素超滤膜浓缩硼改性微粒硅溶胶，其截留率大于93％，可将硼改性微粒硅溶胶浓缩到15％～16％，并且硼改性微粒硅溶胶不易变性。实验采用阴离子及非离子表面活性剂来提高高浓度硅溶胶的稳定性，结果表明，用量0．01％的羧甲基纤维素分散效果最佳，对硼改性微粒硅溶胶的性能几乎没有影响，有利于实现商品化。

硼改性微粒硅溶胶

选用超滤法浓缩硼改性微粒硅溶胶，在室温、操作乐力3.5kPa的条下，选用截留相对分子质量为10000的醋酸纤维素超滤膜浓缩硼改性微粒硅溶胶，其截留率真大于93%,可将硼改性微粒硅溶胶浓缩到15％～16％，并且硼改性微粒硅溶胶不易变性实验采用阴离子及非离子表面活性剂来提高高浓度硅溶胶的稳定性，结果表明，用量0．01％的羧甲基纤维素分散效果最佳，对硼改性微粒硅溶胶的性能几乎没有影响，有利于实现商品化。

改性微粒硅溶胶的结构和形态

用IR谱2、9Si-NMR1、1B-NMR和27Al-NMR谱及透射电镜对铝改性硅溶胶与硼改性硅溶胶进行了结构形态与特征的分析研究,首次提出了铝改性硅溶胶与硼改性硅溶胶的结构和形态特征。铝改性硅溶胶胶粒中的Al主要是以与[SiO4]四面体相连接的[AlO4]四面体的形式存在。硼改性硅溶胶胶粒中的硼主要以与4个硅原子相连接的[BO4]四面体的形式存在,同时还有与3个硅原子相连接的[BO4]四面体的形式。铝、硼改性硅溶胶带有强负电性,颗粒是无定型的,粒径在3 nm左右,属于微粒粒子。

改性微粒硅溶胶的研制及应用机理研究

The preparation and their application in papermaking of aluminium modified silica sol （AMS） and boron modified silica sol （BMS） were first investigated in China.At the same time the structures and configurations of AMS and BMS were first time authenticated.The modified silica sol microparticle system was detailedly and systemically studied with colloid charge titration.On the research of flocculation mechanism the laser sizer was also first time used to determine the floc size.Results showed that sodium silicate was treated and acidification was carried out by means of strongly acid cation exchange resins and obtained almost sodium free acid sols.The acid sol obtained after acidification was then made alkaline.The alkalization was carried out with sodium silicate so that concentration at the preparation could be enhanced and mitigate later condense.Low temperature was in favor of the rate control of particle aggrandizement and smaller and more uniform particles were achieved.The optimal conditions before modification were 8% alkali dosage,heat temperature T12 and heat time 90 minutes.Aluminium and boron modification of the surface were carried out by means of aluminate and borate in order to give particles better charge stability.The retention and drainage efficiency of AMS and BMS were superior to that of imported silica sol NP882 and the retention and drainage efficiency of BMS was superior to that of AMS.And the optimal conditions of aluminium modification were modification degree A3,temperature T24 and reaction time about an hour.Or that of B/Si was 0.08～0.1.Aluminium and boron modification project were feasible and reliable.Ultrafiltration instrument was selected to condense BMS and its optimal conditions were 3.5 kPa pressure with 10 million molecular weight membrane at room temperature.In order to improve the stability of high concentration silica sol,anion or no ion surface actives could be useful.0.01% DBS was found to be the best dispersant and had almost no effect on silica sol which was in favor of its commerciality.AMS and BMS were analyzed by means of FT-IR,29Si-NMR,11B-NMR and 27Al-NMR.The results showed that there were three kinds silicate anions such as Si（OSi）2（OH）2（Q2）,Si（OSi）3（OH）（Q3） and Si（OSi）4（Q4） in unmodified silica sol NP882 surface.Because Al and boron were introduced to silica sol surface,there were only Si（OSi）2（OH）2（Q2） and Si（OSi）4（Q4） in AMS and BMS surface and （Q3） Si（OSi）3（OH） were changed into Si（OSi）3（OAl）3- and Si（OSi）3（OB）3-.In the addition,the Al in AMS particles and B in BMS particles existed mainly in the form of AlO4 or BO4 tetrahedra linked with four Si atoms in the second coordination sphere.From TEM（transmission electron microscopy） AMS and BMS particles were not spherical and size were about 3nm.Furthermore BMS particle size was smaller and more uniform than AMS.Characteristic application process and electrochemistry performance of cationic polymers/modified silica sol （MS） were systemically studied,It was found that CS/MS microparticle retention and drainage aid system had better retention and drainage efficiency in the high shear condition than CS single retention aid system,meantime CS/BMS system was better than CS/AMS system.MS microparticle retention and drainage aid systems were applicable to pulp with high fines such as waste pulp and wheat straw pulp.Seen from the effects of MS microparticle retention and drainage aid systems on wood pulp and waste pulp,CS and CPAM/MS system had better retention and drainage efficiency than CS/MS system and CPAM/MS system.But CS/MS system had best retention and drainage efficiency in wheat straw pulp. In all pulp BMS had better retention and drainage effiency than AMS.CS/MS microparticle retention and drainage aid system was preferably applicable in pH value 4～8 and resin sizing systems with less than 3% aluminium sulfate.This system had good resist capability to electrolyte interfere so that cycle water with less than 100 mM electrolyte could be used resulting in less water resource

APPLICATION OF BORON MODIFIED SILICA SOL ON RETENTION AND DRAINAGE

In this paper it was studied that these dosage effects of CPAM, cationic starch?boron modified silica sol(BMS), Al2(SO4)3, pH value and electrolyte on the retention and drainage of different microparticulate systems including CPAM, cationic starch and boron silica sol. The research results indicated that CPAM had no good retention when used with boron silica sol. The best retention efficiency was the microparticulate system of CPAM + cationic starch with boron modified silica sol; Secondly was that of cationic starch with boron modified silica sol; The worst was that of CPAM with boron modified silica sol. The retention efficiency had no relation with the addition order between CPAM and cationic starch. It was also found that the microparticulate retention system of boron modified silica sol could be used in alum-rosin sizing and in acidity, neutral or alkaline papermaking conditions. This system also could be used with close circulate water so that it could reduce the water pollution and waste.