【作者】 费贵强；

【导师】 沈一丁；

【作者基本信息】 陕西科技大学 ， 制浆造纸工程， 2008， 博士

【摘要】 浆内施胶自1807年沿用至今,虽添加量有所降低,但还未完全被表面施胶所替代。主要原因是目前的聚合物表面施胶剂在应用中仍存在一些重大技术问题,主要是:涂布后仍不能保证达到浆内施胶的效果;抗水性能较差;表面强度差,掉毛掉粉现象仍较严重等。本课题的创新之处在于:（1）可替代浆内施胶,降低湿部化学的多变性和白水循环负担,使造纸实现清洁化生产;（2）产品兼具有机/无机互穿三维网络结构,既具高分子的柔韧性,又具无机的刚性和耐磨性,大幅度提高纸张的综合性能。（3）硅溶胶可赋予纸张表面强化交联结构,产品中的疏水组分和黏结组分与纤维相互作用,增加纤维间的结合强度,改善纸张的耐溶剂性、油墨吸收性、耐洗涤性能等,解决掉毛掉粉现象,实现反应性基团与纤维反应的宏观调控。（4）产品制备过程中不使用有机溶剂和小分子乳化剂,有利于环境保护。本课题通过对反应单体的筛选,在马来半酯可聚合乳化剂（MT）的作用下,选择丙烯酸丁酯（BA）为核单体,丙烯酸丁酯、苯乙烯及硅烷偶联剂KH-570为壳单体制得系列“软核硬壳”核壳乳液,同时引入功能性单体丙烯酸（MAA）。并对乳液的稳定性、微观形貌和流变性能进行了研究,分析了乳胶膜力学性能、耐介质性、结晶性和动态力学性能的影响因素。同时将其用于纸张表面施胶,研究了其对浆内施胶的替代作用。具体结论如下:（1）可聚合乳化剂下核壳乳液的结构与性能红外光谱表明马来半酯可聚合乳化剂上含有可聚合基团双键,而核壳共聚物上不饱和双键的特征吸收峰消失,表明可聚合乳化剂基本完全键合到共聚物分子链上。透射电镜表明核壳乳胶粒呈球形结构,乳胶粒子的核壳结构明显。原子力显微镜（AFM）显示当有机硅含量为0.0%时,胶膜表面相对舒展,平展;而当有机硅含量为2.0%时,胶膜纵断面轮廓线起伏较大。稳定性研究表明当w（MT）＞1.5%,w（ODA）=0.5%,乳液pH值介于7-9,乳液固含量＜40%,分子量调节剂正十二硫醇用量＞1%,w（KH-570）＜2.5%,w（硅溶胶）＜8%时,体系的稳定性较佳。光散射研究表明随着KH-570用量的增加,乳胶粒子的粒径增加;随着w（ODA）的增加,乳胶粒粒径大小呈现先下降后上升的趋势,当w（ODA）为0.5%左右时,乳液分子粒径较小。流变研究表明在低剪切速率下,乳液黏度随着KH-570用量的增加而下降,但当KH-570用量高于1.5%时,乳液黏度又开始上升,颗粒间相互作用增强。而当剪切速率高于1s^-1时,乳液黏度基本与剪切速率无关,而是随着KH-570用量的增加呈现增大的趋势。流变亦表明乳液是一种假塑性流体,且随着硅溶胶用量的增加,乳液的假塑行为增强,黏度增大。力学性能测试表明随着KH-570用量的增加,胶膜的拉伸强度逐渐增加,断裂伸长率下降,但当KH-570的用量超过2.5%后,拉伸强度有所下降。随着硅溶胶用量的增加,胶膜的拉伸强度增加,但当其用量超过6%之后,胶膜脆性增加,拉伸强度下降,断裂伸长率下降。动态力学性能（DMA）测试表明随着KH-570和硅溶胶用量的增加,胶膜的储能模量增加,但当KH-570用量高于2.5%时,硅溶胶用量高于6%时,储能模量又有所下降,刚性减弱。X-射线衍射（WXRD）显示当有机硅烷偶联剂KH-570用量由0.5%增加至2%时,结晶度由3.04%增加至5.12%;但继续增加KH-570用量至3%时,结晶度由5.12%降至4.52%。随着结晶度的提高,材料的耐热性和耐溶剂性有明显的提高。4%硅胶的加入使乳胶膜的结晶度由5.12%增加至10.98%,从而在一定程度上提高乳胶膜的力学性能和耐介质性。热重-微分热重（TG-DTG）研究表明随着KH-570用量的增加,胶膜的热分解温度上升,热稳定性得到改善:但当KH-570用量超过1.5%时,体系的热降解温度又开始下降,热稳定性变差。随着硅溶胶用量的增加,乳胶膜的热降解温度有所提高,热稳定性得到改善。但当硅溶胶用量达10%时,由于相容性问题,热稳定性又有所下降。（2）应用实验当w（乳化剂）=2%,w（KH-570）=2%,w（硅溶胶）=6%,w（正十二硫醇）=2%时,纸张性能较佳。扫描电镜表明,未进行表面施胶的纸张,其表面纤维之间未互相联结,施胶处理后的纸页细小纤维互相粘结成片后和较粗纤维贯串起来,使得纤维编织的更加紧密。单独使用改性淀粉表面施胶时,纸张基本无施胶度,抗张强度为27N,耐折度为140次,环压强度为4.2KN.m/g。随着体系中聚合物乳液BS-1比例的增加,施胶度增加,表面强度有所下降,但下降幅度不大。单独使用BS-1施胶的纸张的抗张强度达35N,耐折度为241次,环压强度为6.8KN.m/g。当m（淀粉）/m（乳液）=2:1时,耐折度可达276次,纸张环压强度可达到7.6 KN.m/g。当将BS-1与PVA复配使用,在相同聚合度下,PVA水解程度越高,纸张性能越佳,但由于PVA溶解后黏度较大,宜采用中等聚合度的PVA。且PVA使用效果强于改性淀粉,经PVA施胶的纸张施胶度达到5s左右,表面强度4.5m/s,而淀粉施胶的纸张施胶度几乎趋于0s。表面强度只有2.8m/s。当m（PVA）:m（BS-1）=2:1时,纸张的耐折度可达326次,纸张环压强度可达到8.5 KN.m/g。替代浆内施胶研究试验表明,当用2.0Kg/吨纸的BS-1表面施胶,浆内AKD中性施胶剂用量为0时,纸张的Cobb可达到24%,表面强度可达到3.9 m/s,纸张性能要优于浆内AKD中性施胶剂用量为18Kg/吨纸,表面施胶AKD用量3Kg/吨纸的纸张。产品工厂大试应用实验亦表明BS-1完全可以在不添加浆内施胶剂的前提下,达到纸张的物理性能指标,当BS-1用量为1.5公斤/吨纸时,纸张性能与德国K-532用量为1.8公斤/吨纸,硫酸铝用量3公斤/吨淀粉液的纸张性能相当。更多还原

【Abstract】 Internal sizing has been widely used since 1807,although the amount has been reduced to certain extent,it has not yet been completely replaced by the surface Sizing.The main reason is that there still exist some major technical problems in the application of polymer surface sizing agent.For example,individual surface sizing still can not guarantee equivalent sizing performance with internal sizing; furthermore,the shortcoming in water resistance and surface strength are still serious.The innovation of this research lies in following four points:（1） Internal sizing procedure can be cancelled through the use of the product,which can reduce the variability of wet-end chemistry and the burden of papermaking whitewater to achieve nonpolluting production. （2） The products are endowed with the structure of organic/inorganic interpenetrating three-dimensional Network,not only possess the flexibility of polymeric material but also rigidity and wear resistance, which can greatly improve the comprehensive properties of paper.（3） strengthening crosslinking structure can be formed in paper surface by the introduction of silica sol.The bonding strength among fibers can be enhanced due to the interaction between active group and fiber, resulting in the improvement of solvent resistance,ink absorption and washing durability.（4） Organic solvent and small molecular emulsifier were not used in the preparation process,which is beneficial to environment protection.In this research,with the action of maleic half-ester polymeri sable emulsifier（MT）,series of core-shell emulsions with "soft co re and hard shell" were prepared with butyl acrylate（BA） as core monomer,and BA,styrene（St） andγ-methacryloxypropyltrimetho xysilane（KH-570） as shell monomers,at the same time,functional monomer methacrylic acid（MAA） was introduced.Factors influen cing the stability,micromorphology and rheological properties of t he emulsion were studied,as well as factors influencing mechanic al properties,medium resistance,crystallinity and dynamic mechan ical properties.Furthermore,the products were applied in paper su rface sizing,and its substitute effect for internal sizing was invest igated.The detailed conclusions were described as following:（1） Structure and properties of core-shell emulsion with action of MTFT-IR spectra indicated that a characteristic peak correspondin g to polymerisable group- double bond was found in the chain str ucture of MT,but this peak disappeared in the core-shell copolym er,indicating that most of polymerisable emulsifier has been bond ed to the molecular chain of copolymer.Transmission electron microscope（TEM） indicated that core-shell emulsions displayed sphere morphology,and a remarkable core-shell structure was detected.Atomic force microscope（AFM） indicated that the surface of the membrane with 0.0%KH-570 was relative smoother, but it became coarse with the increase of KH-570 dosage.It was also found that the stability of the emulsion was optimum under the following conditions:w（MT）＞1.5%,w（ODA）=0.5%,the pH value ranges from 7 to 9,the solid content lower than 40%,w（dodecyl mercaptan）＞1%,w（KH-570）＜2.5%,w（silica sol）＜8%.Light scattering experiment indicates that the particle size of emulsion increases with the increase of KH-570 dosage.While with the increase of w（ODA）,particle size decreases and then increases,and a smaller particle size was found when w（ODA） equals to 0.5%.Rheological investigation was also performed on the system.The viscosity of the emulsion decreased with KH-570 addition,but increased when KH-570 dosage was greater than 1.5%,which can be ascribed to enhanced interaction among particles.However,when the shear rate was higher than 1s^-1,viscosity almost kept invariable with shear rate,but increased with KH-570 and silica sol dosage.It was also found that the emulsion presented pseudoplastic behavior,and an enhanced pseudoplastic was detected with the increase of silica sol dosage.Mechanical test indicates that tensile strength increased gradually with KH-570 and silica sol addition,while the breaking elongation was opposite.However,tensile strength decreased when KH-570 dosage was greater than 2.5%and silica sol dosage greater than 6%.Dynamic mechanical Analysis（DMA） indicated storage modulus increased gradually with KH-570 and silica sol addition.However,it decreased when KH-570 dosage was greater than 2.5%and silica sol dosage greater than 6%.Wide X-ray diffraction（WXRD） indicated that crystallinity increased from 3.04%to 5.12%when KH-570 dosage increased from 0.5%to 2%,however,it decreased from 5.12%to 4.52%when KH-570 dosage greater than 3%.The heat-resistance and solvent resistance can be improved with the increase of crystallinity.Furthermore,the crystallinity increased from 5.12%to 10.98%with 4%silica sol addition,resulting in the improvement of mechanical properties and medium resistance.Thermal Gravimetry（TG-DTG） indicated that the initial decomposition temperature increased with KH-570 and silica sol addition,but thermal stability was weakened when KH-570 dosage higher than 1.5%and silica sol dosage reach 10%.（2）Application experimentThe paper properties reached optimum under following conditions: w（MT）=2%,w（KH-570）=2%,w（silica）=6%,w（dodecyl mercaptan）=2%.Scanning Electron microscope（SEM） indicated that compacted knitted fibers were found after surface sizing.The sizing degree of paper sized with modified starch nearly close to zero,with 27 N tensile strength,140 times folding strength,4.2 KN.m/g ring crush strength.And the sizing degree increased with the increase of polymer emulsion（BS-1）,while surface strength was opposite,with little decrease amplitude.The tensile strength of the paper sized with individual BS-1 reached 35N,folding strength reached 241 times,and ring crush strength reached 6.8KN.m/g.Furthermore,the folding strength reached 276 times and ring crush strength reached 7.6 KN.m/g when m（starch）/m（BS-1）=2:1.When BS-1/PVA blend was applied in paper surface sizing,better papers’ properties were detected while hydrolysis degree of PVA with the same polymerization degree was higher.But PVA with moderate polymerization degree was usually adopted owing to higher viscosity of PVA solution.Besides,the application performance of PVA was better than modified starch.The sizing value of paper sized with PVA is about 5s,the surface strength was 4.5m/s,while the sizing degree of paper sized with starch close to 0s,and surface strength was only about 2.8m/s.Furthermore,the folding strength reached 326 times and ring crush strength reached 8.5 KN.m/g when m（starch）/m（BS-1）=2:1.The test of surface sizing substituting for internal sizing showed that the Cobb value of paper sized with 2.0 kg/t BS-1 and 0g AKD reached 24%,surface strength reached 3.9 m/s,which was better than that of the paper sized with 18 Kg/t internal sizing AKD and 3Kg/t surface sizing AKD.The test in factory also indicated the paper can reach physical performance index with individual BS-1 instead of internal sizing agents.The properties of paper sized with 1.5 Kg/t BS-1 was nearly equal to that of paper sized with 1.5 Kg/t Germany K-532 and 3Kg aluminum sulfate per ton of 5%starch suspensions.更多还原