采用复合分散剂制备高表观密度聚氯乙烯树脂

介绍了高醇解度、高粘度聚乙烯醇 6 35与分散能力较强的其它分散剂按一定配比复合后的使用情况 ,结果表明 :采用复合分散剂 ,可在保持PVC树脂具有适当孔隙率的前提下 ,提高其表观密度 ;采用KH2 0 /6 0SH5 0复合分散剂在 10L釜中制得的PVC树脂表观密度约为 0 .4 6g/mL ;采用 6 35 /B72或 6 35 /F5 0复合分散剂制得PVC树脂的表观密度可比采用通用分散体系提高 10 %～ 15 % ,且水油比减少 ,增塑剂吸收量提高。分析了影响树脂表观密度和颗粒形态的主要因素     

聚乙烯醇助分散剂对悬浮聚氯乙烯树脂颗粒特性的影响

在聚乙烯醇(PVA)/羟丙基甲基纤维素复合主分散体系基础上加入牌号为LM22的PVA助分散剂,研究LM22含量对分散体系界面张力、保胶能力和聚氯乙烯(PVC)树脂颗粒形态的影响。发现随着LM22含量增加,分散剂水溶液-三氯乙烯界面张力和保胶能力降低,PVC树脂平均粒径和增塑剂吸收量增加;随着LM22用量增加,颗粒内部孔隙率增加,初级粒子聚集程度降低,颗粒内部孔径分布变窄。     

使用辅助分散剂改善PVC树脂的颗粒特性

针对目前PVC生产中使用PVA、HPMC二元复合分散体系存在的问题，试验研究了在分散体系中加入辅助分散剂形成三元分散体系来生产PVC-S700型树脂。结果表明：使用辅助分散剂后，PVC树脂质量稳定，表观密度有所降低，增塑剂吸收量提高，树脂颗粒形态均匀，规整性好，粒度分布集中。     

国产聚乙烯醇助分散剂对悬浮法聚氯乙烯树脂颗粒特性的影响

在聚乙烯醇／羟丙基甲基纤维素复合主分散体系基础上加入聚乙烯醇助分散剂。对比研究了国内外同类型聚乙烯醇对分散体系界面张力、保胶能力和聚氯乙烯树脂颗粒形态的影响。结果发现：随着聚乙烯醇助分散剂含量增加,分散剂水溶液一三氯乙烯界面张力和保胶能力降低,聚氯乙烯树脂平均粒径和增塑剂吸收量增加,初级粒子聚集程度降低。     

氯化专用聚氯乙烯树脂颗粒特性的研究——非离子型表面活性剂和链转移剂的影响

水相悬浮法生产氯化聚氯乙烯(CPVC)时,氯化速度和氯化均匀性取决于Cl2在聚氯乙烯(PVC)颗粒中的扩散程度,因而需要有能满足氯化要求的PVC专用树脂。采用以聚乙烯醇(PVA)和羟丙基甲基纤维素(HPMC)为主的复合分散剂,考察Span系列非离子表面活性剂、链转移剂等对PVC颗粒特性的影响。实验结果表明,表面活性剂的加入使PVC树脂增塑剂吸收率、平均粒径和比表面积增大,粒径分布变窄,而表观密度下降;随着链转移剂的加入,PVC树脂增塑剂吸收率、平均粒径和表观密度都增加。     

高白度、高透明性PVC树脂的开发

研究了引发剂、分散剂、终止剂、聚合稳定剂对PVC树脂性能的影响,开发了高白度、高透明性PVC树脂。试验结果表明:该树脂具有表观密度小、增塑剂吸收量大、白度高、透明性好等优点。     

SG5型PVC树脂粒度分布的优化

为了提高PVC树脂的颗粒特性,对聚合生产配方中的分散剂总量、分散剂配比和水油比进行了调整优化。对比了调整前后树脂颗粒的外观形态、平均粒径、筛分频率分布、表观密度和增塑剂吸收量等性能,结果显示调整后的配方能够很好地提升树脂的颗粒特性。     

非离子型表面活性剂对氯乙烯-水界面张力和保胶能力的影响

以聚乙烯醇/羟丙基甲基纤维素(KH20/60SH50)为主分散剂.非离子表面活性剂Span 60为助分散剂,考察氯乙烯悬浮聚合中油-水界面张力和保胶能力随非离子表面活性剂浓度的变化,发现非离子表面活性剂降低界面张力的能力和效率都强于主分散剂,但界面保胶能力不如后者;从Gibbs界面吸附公式和R值理论出发建立非离子表面活性剂、主分散剂在油-水界面上的竞争吸附模型,认为主分散剂/助分散剂混合使用时,助分散剂优先吸附于界面,在降低界面张力的同时也使分散体系保胶能力下降.     

聚合配方调整对PVC树脂质量的影响

为提高PVC树脂质量,采用三元分散体系代替二元分散体系用于氯乙烯悬浮聚合.介绍了配方调整过程,给出了详细的试验数据.根据试验数据进行了配方优化,生产的PVC树脂具有表观密度稳定、增塑剂吸收量高、颗粒形态好、粒度分布集中等优点.     

国产HPMC分散剂在127m3釜上生产PVC树脂的应用总结

上海氯碱化工股份有限公司在127m^3聚合釜中成功试用了国产HPMC分散剂,以替代价格昂贵的进口HPMC分散剂。共进行了50釜的应用试验,试生产了B、D、F三种牌号PVC树脂。通过分析B、D、F三种牌号PVC树脂的常规质量(如,表观密度、VCM残留量、“鱼眼”数及挥发分)、塑化性能、增塑剂吸收量及粒径分布,发现除了F牌号PVC树脂的平均粒径及粒径分布略微变宽、三目集中率略有偏低外,B、D牌号树脂的性能及F牌号树脂的其它性能均无明显变化。同时还指出,F牌号PVC树脂的粒径大小与分布可通过调整分散剂的用量来解决。     

悬浮态乳液聚合条件对聚氯乙烯树脂颗粒特性的影响

Suspended emulsion polymerization of vinyl chloride was carried out in a 5 L autoclave. The influence of agitation, polymerization conversion, dispersant and surfactant on the average particle size (PS) and particle size distribution (PSD), particle morphology and porosity of polyvinyl chloride (PVC) resin was investigated. It showed that the agitator had great influence on the smooth operation of polymerization, PS and PSD. The PS increased and PSD became narrow as polymerization conversion became high. The porosity decreased with the increase of conversion. A convenient choice of additives, both dispersants and non-ionic surfactants, allows one to adjust PS and PSD. The PS decreased with the addition of polyvinyl alcohol or hydroxypropyl methylcellulose dispersants,and increased with the addition of Span surfactants. The addition of dispersants or surfactants also affected the morphology and porosity of resin, and PVC resin with looser agglomeration and homogeneous distribution of primary particles was prepared.     

改性碳酸钙用于聚氯乙烯的研究

研究了一种改性碳酸钙的性质及其在聚氯乙烯中的应用情况。研究结果表明，这种改性碳酸钙与普通碳酸钙相比，具有吸油值低、堆积密度大、分散性好、热稳定性高等特点。填充于聚氯乙烯中，不仅能改善物料的加工性能及制品的物理力学性能，而且还具有较高的热稳定性能。     

复合改性纳米TiO_2的抗紫外性能及其应用

采用硅烷偶联剂(KH570)以及偶联剂和有机物(山梨醇、油酸、钛酸酯、聚乙二醇6000)复合对纳米二氧化钛(TiO_2)进行表面改性,研究了偶联剂和复合改性剂对纳米TiO_2抗紫外性能的影响。通过扫描电子显微镜、二次粒径分析、沉降试验、傅里叶变换红外光谱、同步热分析等对改性前后的纳米TiO_2进行表征。结果表明,KH570+聚乙二醇6000复合改性的纳米TiO_2二次粒径最小,平均粒径为0.047μm;沉降试验中其上清液在350 nm处的吸光度达最高为1.067 76;吸油值最大达86.19 cm~3/g,呈现良好的分散性和疏水性。另外,KH570+聚乙二醇6000改性的纳米TiO_2具有相对最强的紫外吸收能力,而且对亚甲基蓝溶液的降解率相对最小。将改性后的纳米TiO_2添加到PVC基体中,制得PVC/TiO_2薄膜,该薄膜经120 h加速老化后,发现由KH570+聚乙二醇6000改性纳米TiO_2制得的PVC薄膜的光透过率相对最低,拉伸性能最高,体现了其相对优越的抗紫外性能以及KH570+聚乙二醇6000相对优异的改性效果。     

原位悬浮聚合PVC/纳米CaCO3的制备及其性能

利用原位悬浮聚合法制备了聚氯乙烯(PVC)／纳米CaCO3复合树脂,并对其性能进行了研究。结果表明。与PVC相比,PVC／纳米CaCO3复合树脂的热稳定性、增塑剂吸收量及表观密度等有所提高;冲击强度Eh4．9kJ／m^2增加到13．0kJ／m^2：拉伸强度由58．2MPa增加到59．5MPa;断裂伸长率由57．8％增加到75．6％,达到了增韧增强的效果。     

国产聚乙烯醇类分散剂在悬浮法PVC生产中的应用

通过对比目前使用的3种进口聚乙烯醇分散剂(A、B、C)和3种国产聚乙烯醇分散剂(1、2、3)的各项性能,分析了分散剂产品差异的原因,研究了不同国产分散剂替代进口分散剂对悬浮法高聚合度PVC树脂生产工艺参数和产品性能的影响.结果表明:①分散剂1与其他分散剂混合使用效果较好,单独使用分散剂1与同类进口分散剂相比有明显差距;...     

Effect of flame-retardant melamine and dispersants on the mechanical,thermal, and foaming properties of flexible polyurethane foam

The objective of this study was to investigate the effect of adding flame-retardant melamine and five different dispersants on the precipitation, foaming, mechanical, and thermal properties of flexible polyurethane foam (FPUF). Precipitation experiments were conducted to analyze the effect of dispersant on the separation of flame retardant and polyol, and the foaming characteristics of polyurethane (PU) foam after adding dispersant were analyzed. The effect of adding a dispersant on mechanical strength was characterized by measuring tensile strength, tearing strength, and hardness, and scanning electron microscopy analysis was performed to analyze morphological characteristics. Thermogravimetric analysis (TGA) was performed to analyze the thermal properties of PU foam. A horizontal flame test, limiting oxygen index test, and cone calorimeter tests were conducted to examine the flame retardancy of PU foam with flame retardant melamine and dispersant added. The dispersant ANTI-TERRA-U is a solution of a salt of unsaturated polyamine amides and low-molecular acidic polyesters. And, the dispersant BYK-220S is a solution of a low molecular weight, unsaturated acidic polycarboxylic acid polyester with a polysiloxane copolymer. The dispersants ANTI-TERRA-U and BYK-220S improved the density, tensile strength, tear strength, and hardness of FPUF. TGA of the top and bottom portions of the foam showed less weight difference for samples containing dispersants, indicating better homogeneity due to improved dispersibility. Therefore, we conclude that dispersants are beneficial additives to improve the mechanical properties and dispersibility of PU foam.     

The surface modification of diatomite,thermal, and mechanical properties of poly(vinyl chloride)/diatomite composites

Pristine diatomite was first purified by acid treatment and then modified with γ‐methacryloxy propyl trimethoxysilane molecule (KH570) to introduce hydrophobic chains on the surface of acid‐treated diatomite. Fourier‐transform infrared spectroscopy and thermogravimetric analysis (TGA) indicated that the silane coupling agent (KH570) was successfully grafted on the diatomite through covalent bonding. The digital photos showed that the silanization process changed the surface property of the diatomite. The poly(vinyl chloride) (PVC)/pristine diatomite and PVC/modified diatomite composites were prepared via two‐roll mill. The thermal stability and mechanical properties of PVC composites were investigated by TGA, mechanical properties tests, and dynamic mechanical analysis. The results showed that the thermal stability of the composites improved and maximum weight loss temperature (T_max) of the PVC composite with 1 phr modified diatomite was about 20°C higher than that of PVC composite without diatomite. The PVC/modified diatomite composites exhibited better mechanical properties owing to the stronger interfacial interaction between PVC matrix and modified diatomite. But the impact strength reduced sharply when the addition of diatomite was more than 1 phr. The reason of the phenomenon is that the diatomite plays the role of defects in PVC and it works against the absorption of impact strength energy. It was proved by the results of scanning electron microscopy. J. VINYL ADDIT. TECHNOL., 25:E39–E47, 2019. © 2018 Society of Plastics Engineers