双向拉伸聚丙烯薄膜的生产工艺研究

介绍了双向拉伸聚丙烯(BOPP)薄膜的生产方法及工艺流程,分析了原材料、纵横拉伸比、温度等因素对BOPP薄膜物理、力学性能的影响,并且对生产中常见的问题进行了分析,提出了解决铸片常见缺陷及拉伸破膜的方法。     

双向拉伸聚丙烯薄膜铸片成型水槽水循环系统的设计

冷辊水槽铸片成型法是生产双向拉伸聚丙烯(BOPP)薄膜常用的方法,通过优化升级改进了原有结构冷却效果不佳,调节不便等缺陷,使系统结构稳定可靠、操作维护便捷,铸片片材能够快速冷却定型,有效提高了薄膜的生产效率。     

溶液插层法制备BOPP/阻燃硅橡胶复合膜及其性能

使用甲胺溶液对双向拉伸聚丙烯（BOPP）薄膜表面进行活化改性，再采用溶液插层法将阻燃硅橡胶与BOPP薄膜复合制备了BOPP/阻燃硅橡胶复合膜，并研究了复合膜的力学性能、热性能及光学性能。结果表明：BOPP薄膜与阻燃硅橡胶结合紧密，层状结构明显且无层间空隙，无明显分子链团聚现象，复合膜形貌符合实验预期要求；复合膜的弹性模量远高于BOPP薄膜，且与膜层厚度正相关。与阻燃硅橡胶复合，增强了BOPP薄膜的耐热老化性能、热收缩性能，赋予了BOPP薄膜对一般光源进行光散射的性能优势。     

BOPP专用料对薄膜的性能影响研究

BOPP专用料由于具有优异的性能而被广泛应用于BOPP薄膜,为了研究BOPP专用料对薄膜产品性能的影响,利用三层共挤方式分别制备了BOPP专用料和专用聚丙烯两种BOPP薄膜,并对薄膜产品的力学性能、表面张力和光学性能进行了表征.研究结果表明,BOPP专用料薄膜比专用聚丙烯BOPP薄膜的纵向拉伸强度提高了25 MPa,横...     

BOPP薄膜印刷适性的探讨

本文分析了BOPP薄膜的厚度、光学性能、表面润湿张力、摩擦系数、低静电性对BOPP薄膜印刷适性的影响，并提出了BOPP生产控制要素。     

双轴拉伸聚丙烯(BOPP)薄膜工业技术应用和发展

简要介绍了我国BOPP薄膜工业技术的起步和发展,描述了BOPP薄膜工业技术的生产设备和BOPP薄膜生产线的特点。介绍了BOPP薄膜用聚丙烯原料的性能、特点和功能性添加剂的种类性能、用途和发展趋势,以及BOPP薄膜产品的种类和应用。     

国内BOPP膜生产现状及市场预测

介绍了国内双向拉伸聚丙烯(BOPP)薄膜的行业发展状况，包括BOPP薄膜的国内主要生产厂家及生产设备、未来几年的市场需求预测以及拟建BOPP薄膜装置和新产品。     

国内外BOPP薄膜现状及发展趋势

介绍了国内外BOPP薄膜的现状及发展趋势，分析了国内BOPP薄膜分布及供求状况，提出了国内BOPP薄膜行业面对的问题及其它相关内容。     

聚丙烯薄膜的双向拉伸工艺研究

介绍了国内外BOPP薄膜发展现状，阐述了生产中常见的问题并提出了相应的解决办法，最后对影响BOPP薄膜质量的工艺条件——拉伸比和温度，进行了比较深入的探讨。     

BOPP生产线TDO工况监控及调整新方法

针对BOPP生产中横向拉伸（TDO）工段常发生的破膜问题，提出一种通过观察和对比BOPP测厚系统测量数据来判断并监控BOPP生产线TDO的实时工况是否合适的方法。生产实践表明，TDO薄膜的收缩量与TDO破膜次数有直接的关系，通过观察和对比TDO出口薄膜幅宽的收缩量可以实时检查TDO各段的工艺参数是否合适；当TDO出口薄膜幅宽的收缩量较大时应根据破膜形式及位置及时检查调整TDO相关各段温度设定值。     

Experimental studies on the development of a cast film

The cast film process is of significant industrial interest. This work presents quantitative experimental results for the characterization of a film casting operation in the region between the die exit and the chill roll. The polymer melt employed is a commercial PET sample that has been characterized in both shear and extension‐dominated flows. Pointwise measurements of both the film temperature and the local velocity are made over the entire region between the die and the chill roll. The velocity increases in the gap, although the strain rate decreases as the polymer moves from the die to the chill roll. For a particular axial position, the velocity decreases significantly near the edges of the film. There are modest (～20 °C) decreases in the temperature between the die and the chill roll, with the greatest variations again occurring near the edges of the film. The experimental results are explained by the coupling between the temperature, velocity fields, and geometry of the experimental apparatus. POLYM. ENG. SCI. 45:443–450, 2005. © 2005 Society of Plastics Engineers.     

Study on rough-surface biaxially oriented polypropylene film. I. Formation of β-form crystals in sheet cast with T-die extruder

Sheets were cast by extruding polypropylenes (PP) which contained γ-quinacridone, a β-crystal nucleator, at levels of 0–10 ppm using a 30 mm ϕ extruder with a T-die at extrusion temperatures of 200–260°C and chill roll temperatures of 30–90°C. The influences of raw resin characteristics such as γ-quinacridone content and MFI of the base PP and casting conditions such as extrusion temperature and chill roll temperature on the amount of β-crystals formed in the sheet were studied. The amount of the β-crystals formed was larger as the γ-quinacridone content was higher and the extrusion temperature was lower and almost independent of the chill roll temperature. As for the influence of MFI of the base PP, the amount of the β-crystals formed was maximum at MFI ≑ 8 dg/min.     

Influences of processing on the phase transition and crystallization of polypropylene cast films

Phase transition and changes of properties of isotactic polypropylene (i‐PP) cast films with the processing conditions have been investigated by wide‐angle X‐ray diffraction, two‐dimensional small‐angle X‐ray scattering, and atomic force microscopy. It was found that chill roll temperature was a major factor, which influenced the formation of mesomorphic phase and its transition to spherulitic structure. Only mesomorphic phase was observed in the films produced under a chill roll temperature of below 40°C. When the roll temperature was increased to 60°C, mesomorphic phase coexisted with spherulitic crystal structure, and totally transformed to monoclinic structure at the roll temperature of 80°C. Differential scanning calorimetry, tensile, and optical tests were also performed on the films. The results showed that the observed structure changes were closely related to the thermal behavior, tensile, and optical properties of the PP films. The influence of die temperature on the films was also discussed, but the effect was much less than chill roll temperature. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41100.     

Cooling of Paper Using Chill Rollers

A mathematical model is developed to understand the heal transler characteristin ofa chill roll assembly used in the heat-set web-oflset printing industry. Thechill roll assembly permils the waling olpaper after the paper has undergone drying in an oven to allow for hardening of the ink The heat transfer is modelled and solved using a series expansion. The heat conducted from the paper at each roll is calculated from this, as well a temperature distribution through the paper and around the roll. The resulls are compared with a real system and the resulling error is found to be of the order of 5%.     

Cooling of Paper Using Chill Rollers

ABSTRACT

A mathematical model is developed to understand the heal transler characteristin ofa chill roll assembly used in the heat-set web-oflset printing industry. Thechill roll assembly permils the waling olpaper after the paper has undergone drying in an oven to allow for hardening of the ink The heat transfer is modelled and solved using a series expansion. The heat conducted from the paper at each roll is calculated from this, as well a temperature distribution through the paper and around the roll. The resulls are compared with a real system and the resulling error is found to be of the order of 5%.     

Effect of processing on the crystalline orientation, morphology, and mechanical properties of polypropylene cast films and microporous membrane formation

Cast films of a high molecular weight linear polypropylene (L-PP) were prepared by extrusion followed by stretching using a chill roll. An air knife was employed to supply air to the film surface right at the exit of the die. The effects of air cooling conditions, chill roll temperature, and draw ratio on the crystalline orientation, morphology, mechanical and tear properties of the PP cast films were investigated. The crystallinity and crystal size distribution of the films were studied using differential scanning calorimetry (DSC). It was found that air blowing on the films contributed significantly to the uniformity of the lamellar structure. The orientation of crystalline and amorphous phases was measured using wide angle X-ray diffraction (WAXD) and Fourier transform infrared (FTIR). The amount of lamellae formation and long period spacing were obtained via small angle X-ray scattering (SAXS). The results showed that air cooling and the cast roll temperature have a crucial role on the orientation and amount of lamellae formation of the cast films, which was also confirmed from scanning electron microscopy (SEM) images of the films. Tensile properties and tear resistance of the cast films in machine and transverse directions (MD and TD, respectively) were evaluated. Significant increases of the Young modulus, yield stress, tensile strength, and tensile toughness along MD and drastic decreases of elongation at break along TD were observed for films subjected to air blowing. Morphological pictograms are proposed to represent the molecular structure of the films obtained without and upon applying air cooling for different chill roll temperatures. Finally, microporous membranes were prepared from annealed and stretched films to illustrate the effect of the PP cast film microstructure on the morphology and permeability of membranes. The observations of SEM surface images and water vapor transmission rate of the membranes showed higher pore density, uniform pore size, and superior permeability for the ones obtained from the precursor films prepared under controlled air cooling.     

Thermomechanical analysis and modeling of the extrusion coating process

During the extrusion coating process, a polymer film is extruded through a flat die, stretched in air, and then coated on a substrate (steel sheet in our case) in a laminator consisting of a chill roll and a flexible pressure roll. The nip, i.e. the area formed by the contact between the pressure and the chill rolls, constitutes the heart of the extrusion coating process. Indeed, in this region, some of the most critical properties, such as adhesion, barrier properties, optical properties, are achieved or lost. In this article, we first present an experimental investigation of the coating step, which enables to characterize the leading thermomechanical phenomena. It is shown that there is no polymer macroscopic flow in the nip, but a local flow within the asperities of the steel substrate surface. This microscopic flow, at the interface between the film and the substrate, is slowed by strong cooling conditions in the nip. Several models are then proposed, giving access to the temperature profile through polymer thickness and substrate, the pressure distribution in the nip as well as the behavior of the polymer melt in the nip at the interface with the substrate. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

Study of the stability of the film casting process

A theoretical study of the film casting process has been carried out. In this industrial process, a molten polymer is extruded through a flat die, then stretched in air and cooled on a chill roll. This involves mainly an extensional flow. Between the die and the chill roll, thick edges are formed and a neck-in phenomenon is observed. Above a critical take-up speed, a drawing instability, known as draw resonance, may occur. In this paper, a one-dimensional model adapted from the classical model of the fiber spinning is developed (for a Newtonian or a Maxwell fluid). The influence of the processing parameters (draw ratio, Deborah number, and aspect ratio) on geometry of the lateral free surface (the so-called neck-in phenomenon) is studied. An unattainable zone very similar to the one encountered in fiber spinning is predicted, which only slightly depends on the stretching geometry (initial film width and stretching distance). The onset of draw resonance is studied through the linear stability method. A stability zone, depending on the geometry of the process, the elasticity of the polymer, and the draw ratio, has been obtained. This instability is observed with simultaneous width and thickness film variations. It is proved that the aspect ratio (stretching distance divided by die width) has a strong influence on the onset of the draw resonance instability.     

Effect of type and amount of comonomer on the properties of four copolymers of ethylene

The plastics industry is now coming to realize that copolymers are unique thermoplastics which have broad areas of application. It is believed that ethylene-methyl acrylate copolymers of 2 melt index may be extrusion coated to paper by a cap-coat process or by use of a chill roll with an adhesive coating. Copolymers of ethylene and vinyl monomers can be made into film by the same methods used for polyethylene. Methyl acrylate and methyl methacrylate copolymers may be processed on a wide range of molding equipment. Table VII in the article gives a list of applications for each polymer, along with expected physical properties.     

Numerical simulation of the cast film process

The cast film process is studied and a numerical simulation is performed using a finite element method. Two dimensional equations involving the thickness and a mean velocity are used by considering the film as a thin layer. The process is assumed to be isothermal between the die exit and the quick cooling on the chill roll. The width of the film is computed iteratively as a free surface problem by means of a finite element method. The thickness distribution of the film is obtained by a finite volume method. This approach allows modeling of the well known “dog-bone” or “edge bead” defect with a reasonable computation time.