摘要
以正硅酸乙酯(TEOS)和甲基三乙氧基硅烷(MTES)为前驱体,使用溶胶凝胶法对聚磷酸铵(APP)进行微胶囊化改性,通过浆内添加法制备疏水阻燃纸。结果表明,APP为表面光滑的方形结构颗粒,具有强亲水性和负电性。在碱性条件下,TEOS和MTES共同形成致密粗糙二氧化硅壳层,将APP微胶囊化包裹。当MTES添加量为6%时,相比改性前,微胶囊化APP平均粒径由23.98 μm增至28.52 μm,水接触角从13.5°增至97.7°,由亲水性转变为疏水性,Zeta电位由-67.5 mV降至-45.8 mV,负电性减弱。与添加40%改性前APP的纸张相比,添加40%微胶囊化APP的纸张Cobb值由61.7 g/
纸张在使用过程中会因吸水导致强度下降,也会由于易燃性而增加使用过程中发生火灾的风险。如果能使纸张同时具有疏水性和阻燃性,则可广泛应用于包装材料、室内装饰材料等领域,也可用于油水分离滤纸和汽车发动机空气滤纸
聚磷酸铵(APP)作为一种阻燃性能良好的无机磷氮系阻燃剂,是膨胀阻燃体系的重要组成,具有磷氮含量高、热稳定性好等优点,其吸热分解会降低材料的温度,兼具气源和酸源的性质,可广泛应用于聚合物、木材、织物、纸张等材料的加工过程。然而,APP极性高、吸湿性强,在潮湿环境下容易水解和迁移,导致阻燃性减
由于APP具有强亲水性、负电性及一定的溶解性,因此通过浆内添加APP制备疏水阻燃纸的研究较少。耿亚茹等
目前,疏水阻燃纸的制备通常采用浸渍法或涂布法,这些方法增加了生产操作环节,且无法实现材料本征阻燃。通过浆内添加法制备疏水阻燃纸,不仅可以实现材料本征阻燃,还可以降低生产成本。本研究以正硅酸乙酯(TEOS)和甲基三乙氧基硅烷(MTES)作为前驱体,使用溶胶凝胶法对APP进行微胶囊化改性,再通过浆内添加微胶囊化APP制备出疏水阻燃纸,研究疏水阻燃纸的性能,为浆内添加法制备疏水阻燃纸的工业化生产提供一定参考。
本色硫酸盐针叶木浆(打浆度28.5 °SR)、阳离子分散松香胶(固含量35%)、阳离子聚丙烯酰胺(CPAM)、膨润土,由浙江金昌特种纸股份有限公司提供。聚磷酸铵(APP,聚合度≥1000),由杭州熊熊文化科技有限公司提供。正硅酸乙酯(TEOS,质量分数99%)、甲基三乙氧基硅烷(MTES,质量分数98%)、聚乙二醇辛基苯基醚(OP-10,分析纯),由上海麦克林生化科技有限公司提供。氨水(质量分数25%~28%)、无水乙醇(分析纯),由杭州高晶精细化工有限公司提供。
OCA40 Micro表面接触角测试仪,德国德飞;Ultra55场发射扫描电子显微镜(FESEM),德国卡尔蔡司;Nicolet is50傅里叶变换红外光谱仪(FT-IR)、Alpha XPS X射线光电子能谱分析仪(XPS),美国赛默飞;Zetasizer Nano ZS纳米粒度电位仪,英国马尔文;ZR-01智能氧指数测定仪,青岛睿新杰仪器有限公司;Mastersizer 2000激光粒度分析仪,英国马尔文。
采用溶胶凝胶
采用FESEM检测APP和微胶囊化APP的表面形貌。样品经镀金处理,在工作电压为3 kV下进行测试。
将KBr与APP及微胶囊化APP分别混合,研磨成粉末后压制成片,采用FT-IR分析官能团变化。扫描范围500~4000 c
采用XPS检测APP和微胶囊化APP表面的元素含量,功率250 W(12.5 kV×20 mA)。
采用表面接触角测试仪在室温下测量压片后APP的水接触角,每组样品重复测量3次,结果取平均值。
采用纳米粒度电位仪和激光粒度分析仪对APP和微胶囊化APP进行Zeta电位及粒径测试。将样品分散在去离子水中超声5 min后测试,每组样品重复测量3次,结果取平均值。
参照GB/T 5454—1997《纺织品燃烧性能试验氧指数法》,使用智能氧指数测定仪对疏水阻燃纸进行LOI测试。

图1 MTES添加量对微胶囊化APP水接触角的影响
Fig. 1 Effect of MTES addition on water contact angle of microencapsulated APP
样品 | 接触角/(°) | Zeta电位/mV | 平均粒径/μm |
---|---|---|---|
APP | 13.5±3.0 | -67.5 | 23.98 |
微胶囊化APP | 97.7±4.0 | -45.8 | 28.52 |

图2 APP的微胶囊化改性示意图
Fig. 2 Schematic diagram of microencapsulated ammonium polyphosphate

图3 APP在水中部分电离的示意图
Fig. 3 Diagram of partial ionization of APP in water
APP和微胶囊化APP表面形貌如

图4 APP及微胶囊化APP的FESEM图
Fig. 4 FESEM images of APP and microencapsulated APP

图5 APP及微胶囊化APP的FT-IR谱图
Fig. 5 FT-IR spectra of APP and microencapsulated APP
XPS仅对样品最外层的3~10 nm表面敏感,使用XPS分析表面的元素组成,可以确定APP的微胶囊化改性是否成功。APP和微胶囊化APP的XPS谱图如

图6 APP、 微胶囊化APP的XPS谱图
Fig. 6 XPS spectra of APP and microencapsulated APP
样品 | 元素含量 | ||||
---|---|---|---|---|---|
O | C | N | P | Si | |
APP | 38.33 | 27.78 | 20.55 | 13.36 | 0 |
微胶囊化APP | 50.20 | 20.53 | 5.60 | 5.83 | 17.83 |

图7 APP添加量对疏水阻燃纸Cobb值的影响
Fig. 7 Effect of APP dosage on the Cobb value of hydrophobic flame retardant paper
添加改性前后APP对疏水阻燃纸抗张指数的影响如

图8 APP添加量对疏水阻燃纸抗张指数的影响
Fig. 8 Effect of APP dosage on tensile index of hydrophobic flame retardant paper
APP添加量对疏水阻燃纸LOI的影响如

图9 APP添加量对疏水阻燃纸LOI的影响
Fig. 9 Effect of APP dosage on LOI of hydrophobic flame retardant paper
3.1 聚磷酸铵(APP)呈方形结构,表面光滑,水接触角为13.5°,Zeta电位为-67.5 mV,具有强亲水性和强负电性。
3.2 当甲基三乙氧基硅烷(MTES)添加量为6%时,微胶囊化APP被致密粗糙的二氧化硅壳层包裹,平均粒径由23.98 μm增至28.52 μm,水接触角由13.5°提升至97.7°,Zeta电位由-67.5 mV转变至-45.8 mV。
3.3 与添加40%APP的疏水阻燃纸相比,添加40%微胶囊化APP的疏水阻燃纸的Cobb值由61.7 g/
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