Effect of paper and printing press variables on the rates of adhesion failure in the linting of offset printing

Lint problems occur when loosely bonded particles detach from the surface of uncoated paper and accumulate on the printing blanket. We investigated the effect of paper and the printing press variables of printing tone and ink tack on linting using a lint camera system and also by stopping the press repeatedly to wash the lint samples off the blanket. Lint particles were classified into small particles (with area 0–8000?μm²) and large particles (with area above 8000?μm²). There have been many contradictory reports about the most important paper and printing variables affecting linting because many previous researchers have not adequately addressed that linting is a dynamic process, which involves two adhesion failures and separations, driven by the splitting of the viscous ink film. The first failure is for the removal of lint particles from the paper surface to the blanket, while the second failure is for the separation of the lint particles from the blanket. The key finding of this study is that these two rates of adhesion failure are generally correlated. That is, a higher rate of lint particle separation from the paper surface is associated with a higher rate of separation from the blanket. This finding held for varying the grade of paper, the ink viscosity and the printing tone, and for small and large particles. Previous contradictory results from linting studies are because lint has only been measured after completing a printing trial, with no means of examining the two underlying adhesion failure processes.     

聚丙烯酸酯乳液粒度及其压敏胶粘性能的研究

采用预乳化半连续聚合工艺,制备了乳液型聚丙烯酸酯类压敏胶。讨论了乳化剂用量、引发剂用量、预乳液滴加时间和搅拌速率对乳胶粒粒度以及压敏胶粘接性能的影响。实验表明:在不同影响因素下,乳胶粒的粒度与压敏胶粘接性能之间呈现出不同的变化关系。     

数字成像颗粒分析仪在聚乙烯粉料测试中的应用

采用CAMSIZER数字成像颗粒分析仪对聚乙烯粉料样品的粒度分布进行了测试,考察了测试结果的重复性,并对该仪器在粒度分布测试同时获得颗粒球形度数据和颗粒照片的功能进行了验证。结果表明,粒度分布测试自动化程度高,结果重复性较好,与筛分法比较,工作量大大降低,但测试速度有待提高;在进行粒度分布测试的同时,可获得颗粒的球形度数据和颗粒投影照片。     

Standardized Weibull statistics of ceramic strength

In order to estimate Weibull parameters in the Weibull statistical fracture theory as truly material properties independent of specimen geometry and loading mode, first the Weibull statistical fracture theory is transformed into the ordinary Weibull distribution function under certain approximation. Then the standardized format of ordinary Weibull distribution is introduced to enable Weibull modulus as the single parameter for estimation via the maximum likelihood method. The method of using standardized Weibull distribution for strength data synchronization and Weibull modulus estimation is validated by analyzing extensive strength data sets measured from uniaxial flexure, biaxial flexure and their combination, and from smooth and notched specimens. The technical path to estimate the scale parameter and threshold strength as material properties in the Weibull statistical fracture theory and effect of sample size on the estimation accuracy are also discussed.     

计算机图像处理技术用于微粒的定量测量

基于ＰＣＩ总线的图像采集卡,采用计算机图像处理、人工智能技术实现了对颗粒的定量分析。详细阐述了颗粒定量分析技术及原理、系统组成和软件设计。测试结果表明,该法操作简便、测试速度快、重复性好     

石灰石水泥颗粒分布与其强度的灰色关联分析

将石灰石和水泥熟料按不同比例混合共同粉磨,运用灰色关联分析方法,研究了石灰石水泥颗粒分布对强度的影响,并建立了28d抗压强度与0~40μm颗粒含量的GM(1,2)灰色模型。研究结果表明:石灰石水泥粉体中10~20μm的颗粒含量与3d强度的关联度最大,20~30μm对28d强度影响最大。     

激光粒度仪测量PVC树脂粒径的影响因素

通过激光粒度仪仪器参数设置和不同样品加入量的对比试验,确定了测量PVC树脂粒径分布的Mastersizer 3000型激光粒度仪最佳仪器参数:搅拌速度2 700 r/min、超声时间60 s、遮光度7.0％～9.0％.     

激光粒度分析仪在微细粒级荧光粉粒度测量中的应用

采用激光粒度分析仪对某种微细粒级荧光粉运用不同的样品循环运动速度和加载超声波进行粒度组成与分布的测量。通过正态曲线叠加比较获得:该微细粒级荧光粉颗粒平均直径为4.128μm,中值为3.145μm,标准差为3.930μm,变异系数为95.10%,众数为4.048μm,并测得不同粒径颗粒所占的质量分数。结果表明,该方法是粉末粒度及粒度分布测量的准确方法。     

颗粒定量测量的计算机图象处理技术研究

采用计算机图象处理、人工智能技术实现了对颗粒的定量分析,阐述了颗粒定量分析技术及原理、系统组成和软件设计。测试结果表明,该法操作简便、测试速度快、重复性好。     

An experimental study on adhesion between steel and cement pastes using particle probe scanning force microscopy

This paper presents a method of using particle probe scanning force microscopy to measure the adhesion between steel microspheres and cement pastes. Particle probes were fabricated by attaching steel microspheres to the free ends of microcantilevers. Adhesive forces were collected between steel microspheres and new (4-week old) and old (6-month old) cement substrates in air and saturated lime water. For new cement in saturated lime water, adhesive forces between steel and low density C-S-H, high density C-S-H and other hydrated products were intermediate among all groups selected. The adhesive forces between steel and calcium hydroxide were the smallest, whereas the adhesive forces between steel and the unreacted phases were the largest. For the 6-month old cement, the interweaving of calcium carbonate crystals and C-S-H during carbonation generated greater adhesive forces to steel.     

Measurement of particle size distribution of tripalmitin crystals in a model solution using a laser diffraction method

The form and size distribution of tripalmitin (PPP) crystals formed by quenching a solution in a batch crystallizer have been studied using scanning electron microscopy and a laser diffraction technique. Although the accuracy of the laser technique for particle sizing was affected by the nonsphericity of the crystals, the technique proved to be effective and very reproducible. Crystals recovered by filtration and sonication for laser sizing exhibited markedly different particle size distributions (PSD) and shapes compared to those prepared using another standard route, namely, suspension in butanol and centrifugation. Solutions of 2–10 wt% PPP in a paraffin solvent were crystallized at 25–40°C and displayed two ranges of behavior: (i) rapid growth under strongly supersaturated conditions, yielding narrow PSD of plate and needle-like crystals; and (ii) slow growth in the metastable regime, yielding spherulitic aggregates of platelets that broke down under sonication during preparation for laser sizing. Suspension in alcohol followed by centrifugation yielded aggregates that did not break down under sonication, indicating that the sample preparation route affected the result of the analysis.     

The potential of current high‐resolution imaging‐based particle size distribution measurements for crystallization monitoring

High‐speed, in situ video microscopy is a promising technology for measuring critical solid‐phase properties in suspension crystallization processes. This paper demonstrates the feasibility of high‐resolution, video‐imaging‐based particle size distribution (PSD) measurement by applying image analysis and statistical estimation tools to images from a simulated batch crystallization of an industrial photochemical. The results also demonstrate the ability to monitor important quality parameters, such as the ratio of nuclei mass to seed mass, that cannot be monitored by conventional technologies. General recommendations are given for achieving appropriate sampling conditions to enable effective imaging‐based PSD measurement. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

Calculation of the particle size distribution in suspension polymerization using a compartment-mixing model

A modelling strategy for effective estimation of the particle size distribution (PSD) in suspension polymerization is presented. The strategy consists of coupling a population balance equation (PBE) and a compartment-mixing (CM) model to account for the non-homogeneous mixing in the tank reactor. The values for the rate of energy dissipation of each compartment are estimated from Computational Fluid Dynamics (CFD) calculations and experimental reports on systems with the same agitator and geometric characteristics. Model predictions using the CM model are compared with predictions that assume homogeneous mixing and experimental data on PSD from styrene and divinylbenzene pilot-plant suspension polymerization reactors of 1 and 5 L with Rushton and PBT impellers.     

Usefulness of surfactants in reducing particle adhesion and their effectiveness in cleaning silicon wafers

The effectiveness of surfactants (sodium dodecyl sulfate and dodecyl amine hydrochloride) in the cleaning of silicon wafers has been investigated using atomic force microscopy and image analysis. Recognizing that the surface of SC-1-cleaned silicon wafers is essentially SiO₂ atomic force microscopy was used to determine the interaction forces for the silica/silica and silica/alumina systems with and without surfactant present in solution. Experimental force vs. separation distance curves were found to be in good agreement with theoretical predictions based on electrostatic and van der Waals interactions. Interestingly, the pull-off forces obtained from atomic force microscopy measurements were very close to the adhesion forces calculated on the basis of van der Waals interactions at very close separations. The results from image analysis further confirmed the usefulness of surfactants in reducing particle adhesion and their effectiveness in cleaning silicon wafers. Finally, the results from this study suggest that a more complete understanding of particle interaction forces should be of considerable importance to the electronics industry.     

粒度在线检测技术在微球催化剂装置的应用

微球催化剂装置使用在线湿法粒度仪作为产品粒度分布在线监测手段,通过实时分析结果及时反馈产品粒度分布,以便及时调整操作条件,保证催化剂产品粒度分布合格。通过对比在线湿法粒度仪分析结果与班样的分析结果,得出满足装置需要的在线湿法粒度仪在线分析参考值:(0~20) μm为4.3%~4.8%,(0~40) μm为 22.0%~22.8%,(0~149) μm为92.0~92.6%,该条件下生产的催化剂产品的粒度分析结果可以满足生产需要。     

粗骨料颗粒级配对混凝土抗折强度的影响

粗骨料最大粒级及颗粒级配影响混凝土的抗折强度,本文主要研究了粗骨料最大粒级、粗骨料单级配、二级配、三级配对混凝土抗折强度的影响。研究表明,粗骨料的最大粒级及颗粒级配对混凝土抗折强度影响很大,合理的最大粒级和级配能够提高混凝土的抗折强度。     

Preparation of aqueous dispersible polyurethane: Effect of acetone on the particle size and storage stability of polyurethane emulsion

An aqueous dispersible polyurethane was prepared by the reaction of hydroxyl‐terminated poly(ethylene adipate), dimethylol propionic acid, 4,4′‐diphenylmethane diisocyanate, and ethylene glycol. Formation of the dispersion was achieved by phase inversion of an acetone solution of the polyurethane with water, utilizing carboxylate anion groups as the internal emulsifying sites. The amount of acetone added has a large effect on the particle diameter (0.08 to 8.61 μm) and particle size distribution of the polyurethane emulsion. The storage stability was evaluated in terms of particle size distribution breadth. The aqueous emulsion obtained with no use of acetone was sufficiently stable in storage for at least 6 months. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3455–3461, 2004     

磷渣颗粒级配与磷渣水泥强度的关系

将3个工厂的磷渣,按粉磨时间序列处理成若干不同颗粒级配的试样,配制成一系列磷渣硅酸盐水泥(磷渣掺量均为30%),进行胶砂强度检验。采用灰色关联分析方法研究磷渣各粒径范围颗粒含量与水泥强度之间的关系。结果表明,磷渣中含磷量不同,磷渣的颗粒分布对水泥各龄期强度的影响也有很大差异,即磷(P2O5)质量分数为3.5%,粒径<10μm的磷渣颗粒对强度有削弱作用;磷(P2O5)质量分数为1.44%,粒径<10μm的磷渣颗粒对强度有增强作用;磷(P2O5)质量分数为2.64%,粒径<10μm的磷渣颗粒对3d强度有削弱作用,而对28d强度有增强作用。     

悬浮法PVC树脂颗粒性能的控制

分析了悬浮法PVC生产过程中树脂颗粒特性的影响因素,提出了相应的控制措施.介绍了工艺优化后悬浮法PVC树脂的质量提升情况,并与国内外同类树脂进行了比较.     

高性能粒度调配水泥及其在混凝土中的应用研究

通过设计和调配水泥组分的细度和颗粒分布,制备了一种高性能粒度调配水泥,并测试了该水泥及其配制的混凝土的物理力学性能。试验结果表明:粒度调配水泥的标准稠度用水量与普通球磨水泥相当;在相同熟料含量条件下,粒度调配水泥比对比水泥的抗压强度提高3～4MPa;在混凝土应用中,粒度调配水泥和普通球磨水泥相比具有更为明显的性能优势,利用粒度调配水泥配制的C60高强混凝土不但工作性能良好,而且力学性能优异,28d抗压强度达到了96.1MPa。