【作者】 袁广翔；

【导师】 戴红旗；

【作者基本信息】 南京林业大学 ， 制浆造纸工程， 2011， 博士

【摘要】 随着造纸白水封闭循环程度的提高,湿部环境逐渐恶化,现有的化学助剂往往无法获得正常的应用效果,给生产过程和纸产品性能都带来了不利的影响。以往的工作主要分别研究白水封闭循环中积累的阴离子DCS(溶解及胶体物质)以及无机盐电解质物质对造纸的影响,而阴离子DCS物质与无机盐电解质共同作用则往往被忽视。并且在研究无机盐电解质的影响规律的时候,通常仅以电导率为参数却没能考虑钙镁离子带来的硬度的影响。为此,本文选用了漂白桉木KP浆作为纤维原料,选用造纸白水封闭循环系统中最常见的钙盐和钠盐作为无机盐电解质的模拟物,还选用了松香酸钠,草酸钠,硬脂酸钠作为阴离子DCS物质的模拟物,研究分析了无机盐,阴离子DCS物质以及它们之间的相互作用对造纸湿部及纸页性能的影响。文章还将钙离子控制剂ACS应用于造纸过程,研究了其使用效果。论文研究结论如下：钙离子对漂白桉木浆纤维的吸附过程不符合一级反模型,但是与伪二级反应动力学吻合度较高；吸附过程符合Langmuir等温吸附反应模型；298K,pH值为7.5时,漂白桉木浆羧基含量0.0366mmol/g,钙离子对漂白桉木浆吸附量为0.0165mmol/g,基本满足两个羧基吸附一个钙离子的模型。钙离子与纤维表面的羧基生成羧酸钙,纤维上带负电的活性羧基基团因此被屏蔽,从而影响了CPAM,AKD,CS等阳离子助剂的使用效果。钠离子对纤维羧基活性基团的吸附作用弱,对阳离子助剂性能的影响小增加纸料中金属离子的浓度会对湿部和纸性产生以下影响：1,使纸料Zeta电位上升,钙离子的影响高于钠离子,纸料Zeta电位ζ随电导率σ以及初始Zeta电位值ζ0的变化符合以下的数学回归方程：使用氯化钙调节纸料电导率时ζ=0.388+0.988ζ0+0.202lnσ-0.0914lna×ζ0,使用氯化钠调节纸料电导率时ζ=-0.806+0.960ζ0-0.316lnσ-0.1021na×ζ0。2,使得未添加助剂的纸料滤水和留着性能上升而使得添加助剂的纸料滤水和留着性能下降,钙离子对纸料滤水和留着性能的影响大与钠离子。3,降低AKD的施胶效果,钙离子的影响大于钠离子。4,影响纸页的强度性能,对于抗张指数,耐破指数,耐折度的提升作用,钠离子比钙离子大；对于撕裂指数的削弱作用,钙离子又要大于钠离子。DCS模拟物对湿部和纸性会产生以下的影响：1,使纸料留着滤水性能发生波动,但添加了PDADMAC,CPAM等助剂后,由于阴离子垃圾捕集剂等助剂对DCS模拟物的捕集作用,纸料的滤水和留着性能变得稳定；2,草酸钠使纸页施胶效果的下降。而随着松香酸钠和硬脂酸钠浓度的增加,纸页的施胶效果先上升后下降；3,明显降低纸页的强度性能。钙离子与DCS模拟物的共同作用会对湿部和纸性产生影响：1,使纸料留着滤水性能下降。2,含有一定浓度DCS模拟物的纸料中增加钙离子的浓度,纸页的施胶性能先上升后下降。3,抑制纸料中DCS模拟物对纸页强度性能的影响,使纸页耐折度和抗张指数上升。相比于钙离子,钠离子与DCS模拟物的共同作用对湿部和纸性的影响较小。实验分析得出,钙离子易与DCS模拟物生成沉积物,对纤维表面的活性羧基以及阳离子助剂能产生屏蔽作用,是影响化学助剂应用效果的最根本原因。钙离子是导致白水封闭循环难以实现的决定性因素。控制钙离子的影响则可以大大提高阳离子助剂的使用效果。此时尽管白水封闭循环中依旧会积累可观的钠离子,使得白水电导率保持在很高的水平,纸料的留着滤水性能,纸页的施胶,强度等性能仍然会大大高于钙离子未得到控制之前的状况。因此,控制钙离子的影响对于实现造纸白水封闭循环具有重大的意义。一定浓度CaCl2(调节纸料电导率至4051μs/cm)和DCS模拟物(0.02g/L皂化松香+0.02g/L草酸+0.02g/L皂化硬脂酸)的纸料中：ACS添加量为0.12%时,纸料游离度由300ml升高到340ml；白水浊度从105NTU下降到47.6NTU。纸性方面,ACS添加量为0.4%时,纸页白度从80.61%上升到83.56%,Cobb值从73.5g/m2下降到42.2g/m2,各方面强度也有不同程度的提高。ACS是一种实验室自制化学药品,它能够控制钙离子的影响,减少沉积物的生成,降低钙离子对阳离子助剂和纤维表面活性羧基基团的电荷屏蔽作用。将ACS用于湿部可以取得良好的应用效果。改变纸料中ACS的添加量和钙离子的浓度,检测各纸料的留着滤水性能和纸页性能指标,得出的数据经过回归分析计算,ACS的添加量AACS、钙离子浓度CCa针对纸料和纸页的各项性能指标的二阶回归方程如下：游离度=422-0.771CCa+269AACS+2.06AACS×CCa-2321(AACS)2 +3.00×10-4(CCa)2；白水浊度=37.2-0.117CCa-221AACS-0.782AACS×CCa+1290(AACS)2 +1.20×10-3(CCa)2；Cobb值=19.5+1.43×10-3CCa-10.1AACS-5.48×10-2AACS×CCa +78.3(AACS)2+5.10×10-5(CCa)2；撕裂指数：-0.335+5.28×10-4CCa+0.321AACS-6.23×10-4AACS×CCa-0.996(AACS)2+10-6(CCa)2；抗张指数=41.6-2.62×10-2CCa +28.0AACS+0.119AACS×CCa-153(AACS)2+1.01×10-4(CCa)2；耐破指数=2.11+4.18×10-3CCa-0.201AACS+8.28×10-3AACS×CCa+3.55(AACS)2-1.3×10-5(CCa)2；耐折指数=6.86+5.44×10-2CCa+18.7AACS+0.128AACS×CCa-129(AACS)2。ACS用量与钙离子浓度对纸料和纸页各项性能指标的回归方程的相关系数较高,证明了ACS对纸料和纸页性能的帮助源于对钙离子的控制。并且实际生产中可以根据纸料中钙离子的浓度计算出所需要添加的ACS的量,从而达到所需的纸料和纸页性能指标,这对于实现白水封闭循环具有重要的现实意义。更多还原

【Abstract】 The effects of chemical additives decreased because the wet-end environment deteriorated along with closing white water circuit. It will influence the papermaking processes and properties of paper. The past works mainly focused on the influence of anionic DCS (dissolved and colloidal substance) and inorganic salts. However the impact by the interaction of anionic DCS with inorganic salts is usually ignored. In the same time, hard degree is failure to take as consideration when conductivities are chose as the parameter. For the reasons above, bleached Eucalyptus globulus kraft pulp was chose as fiber material in this paper. Beside that, calcium salt and sodium salt which were common in the white water circuits were chose to represent the inorganic salts, saponify rosin, sodium oxalate and saponify stearic acid were chose as the anionic DCS simulacra. The effect on the properties of wet-end and paper sheets by inorganic salts, anionic DCS and the synergistic effect between them were investigated. As results, calcium ions were the key reason to influence the effect of chemical additives for forming deposits with DCS simulacra, screening the anionic charge of the adsorption sites in fibers. Main results as follows:The adsorption between calcium ions and bleached Eucalyptus globulus KP fibers conformed to Pseudo-second-order kinetics model but not the first-order kinetics model. The adsorption isotherms of Ca2+ by bleached Kraft eucalyptus pulps agrees with the ionic reaction model between carboxyl groups of fibers and Ca2+. In 298K, pH 7.5, the molar ratio of carboxyl to Ca2+ is close to 2:1. Because of the strong binding capacity with carboxyl groups, Ca2+ can screen the anionic charge of carboxyl acid groups, so the electrostatic adsorption between cationic addition agents like CPAM, AKD, CS, etc and the adsorption sites of fibers are affected. The binding capacity with carboxyl groups and Na+ is weaker; it has a small effect on the properties of cationic addition agents compared to Ca2+.The wet-end and hand sheets properties will be affected in the following ways when the concentrations of metal ions increasing:1, Bringing up the Zeta potential of pulp, the Zeta potential reducing effect of calcium ions are stronger than sodium ions. The mathematic relationship of the Zeta potential of the pulp(ζ), the conductivity of pulp(σ) and the original Zeta potential of pulp(ζ0) met the following mathematic models:when regulating conductivity of pulp by calcium chloride:ζ=-0.388+0.988ζ0+0.2021na-0.09141na×ζ0; When regulating conductivity of pulp by sodium chloride:ζ=-0.806+0.960ζ0-0.3161na-0.1021nσ×ζ0.2, Enhanced the retention and drainage ability of pulp when no addition agents was added; when addition agents were added in pulp, the retention and drainage ability of pulp declined, the effect on reducing retention and drainage ability of pulp from calcium ions was stronger than from sodium ions.3, Reducing the sizing effect of AKD, the reducing effect from calcium-ion was stronger than from sodium-ions.4, Affecting the strength properties of hand-sheets, the tensile, folding endurance and burst lifting effects of sodium ions are strong, the tear reducing effect of calcium ions are worse.The effects of three different kinds of DCS simulacra on paper making were investigated:1, The properties of pulp fluctuated because of the appearance of DCS simulacra, but when PDADMAC, CPAM, etc are added in the pulp, because their abilities of capturing DCS simulacra, the retention and drainage properties of pulp become stable.2, Sodium oxalate impairs the sizing effect of AKD. However, the sizing effect of hand-sheets increased and then decreased when saponify stearic acid and saponify rosin content of the pulp increased.3, DCS simulacra reduced the strength properties of hand-sheets.The deposits formed by Ca2+ and DCS simulacra will affect wet-end and paper sheets properties:1, Reduced the retention and drainage abilities of pulp.2, Increasing the concentration of calcium ions in the pulp which already contained certain concentration of DCS simulacra, the sizing effect of hand-sheets increased and then decreased.3, Inorganic salts restrain the impact to strength properties of hand sheets by DCS simulacra. However sodium salts had small effect on the retention and drainage abilities of pulp and the sizing effect of hand-sheets.Calcium ions were the most important factor that made the achievement of closing white water circuit so difficult. It would increase the effect of cationic additives by controlling the influence of calcium ions. Even though the accumulating sodium ions make the conductivity of white water still high, the properties of wet end and paper sheets will be improved by means of removing of calcium ions from the paper making system. So, calcium ions controlling was very important for closing white water circuit.A home made chemical addition agent (ACS) had been used to control the bad influence of calcium ions in closing white water circuits. Good results had been made when put ACS into the pulp that contained a certain concentration of CaCl2 (the conductivity of pulp was 4051μs/cm regulated) and DCS simulacra (0.02g/L saponify rosin; 0.02g/L sodium oxalate; 0.02g/L saponify stearic acid). Main results as follows:when the dosage of ACS was 0.12%, the CSF of pulp increased from 200ml to 340ml; the turbidity of white water dropped from 105NTU to 47.6NTU. In paper properties, when the dosage of ACS was 0.4%; the white degree of hand-sheets increased from 80.61% to 83.56%; the Cobb value dropped from 73.5g/m2 to 42.2g/m2, the strength of hand-sheets also increased in different degrees.Changing the dosage of ACS and the concentration of calcium ions in the pulp, detected the properties of pulp and paper sheet. The order autoregressive scheme of the dosage of ACS in pulp (AACS), concentration of calcium (CCa) to the properties of pulp and hand sheets as follows:Freeness=422-0.771CCa+269AACs +2.06AACS×CCa-2321(AACS)2+3×10-4(CCa)2; Turbidities of white water=37.2-0.117CCa-221AACS-0.782AACS×CCa+1290(AACS)2+1.2×10-3(CCa)2;Cobbvalue=19.5+1.43×10-3CCa-10.1AACS-5.48×10-2AACS×CCa+78.3(AACS)2+5.1×10-5(CCa)2; Tear index=0.335+5.28×10-4CCa+0.321AACS-6.23×10-4AACS×CCa-0.996(AACS)2+10-6(CCa)2; Tensile index=41.6-2.62×10-2CCa+28.0AACS +0.119AACS×CCa-153(AACS)2+1.01×10(CCa)2; Burst index=2.11+4.18x10-3CCa-0.201AACS +8.28×10-3AACS×CCa+3.55(AACS)2-1.3×10"5(CCa)2; Folding index=6.86+5.44×10-2CCa+18.7AACS +0.128AACs×CCa-129(AACS)2.The correlation coefficients of the order autoregressive scheme of the dosage of ACS and concentration of calcium to the properties of pulp and hand sheets were high; it proved that the increased properties of pulp and paper were based on the controlling of calcium ions. For achieving the needed properties of pulp and paper, the dosage of ACS can be calculated according to the concentration of calcium. This will be meaningful to carry out closing white water circuit.更多还原