paper pro
Coated papers have an excessive impact on the appearance and utility of printed materials with respect to the increase in mechanical strength, print gloss and print density. Styrene–butyl acrylate copolymers were synthesized utilizing different emulsifier systems and modified with acrylamide. These lattices were evaluated as paper coats in the presence of kaolin, calcium carbonate and a mixture of both as pigments. The evaluation aimed at employing these lattices on recycled white and brown paper substrates with respect to their mechanical properties and their printability. The tensile strength of coated papers was upgraded by ~ 20–30% in CD compared with that of uncoated papers. The improvement ratio was ~ 12–16% in bursting strength compared with that of the uncoated paper. The maximum gloss values (39 and 48) and the maximum print density values (2.51 and 2.44) were obtained for ground calcium carbonate “GCC” composites on white and brown bases, respectively. Formulas containing GCC had a uniform printed surface with high-quality ink distribution without any picking up of coated surface. This work is a promising one as efficient synthesized binders and a local pigment were employed besides achieving offset printing on recycled brown papers for the first time.
就机械强度,印刷光泽度和印刷密度的增加而言,涂布纸对印刷材料的外观和实用性产生了过度影响。苯乙烯-丙烯酸丁酯共聚物是利用不同的乳化剂体系合成并用丙烯酰胺改性的。在高岭土,碳酸钙和两者的混合物作为颜料的存在下,将这些格子评估为纸涂层。评估旨在就回收的白纸和棕色纸基材上的机械性能和可印刷性采用这些晶格。与未涂布纸相比,CD涂布纸的拉伸强度提高了约20–30%。与未涂布纸相比,破裂强度提高了约12-16%。对于磨碎的碳酸钙“ GCC”复合材料,分别在白色和棕色基础上获得了最大光泽度值(39和48)和最大打印密度值(2.51和2.44)。包含GCC的配方具有均匀的印刷表面和高质量的油墨分布,而没有任何涂层表面的堆积。这项工作是有前途的,因为除了首次在回收的棕色纸上实现胶版印刷外,还使用了有效的合成粘合剂和局部颜料。
Keywords Nanoemulsion binder · Recycled papers · Coated papers · Mechanical properties · Printability · Offset printing
The consumption of coated paper and board is about 45 million tons per year [1]. The global paper packaging market is predictable to reach $307 billion by 2020. The main purpose of coating is to improve the surface quality of paper or board. The * H. M. El-Sherif 1 Polymers and Pigments Department, National Research Center, Cairo, Egypt 2 Chemistry Department, Faculty of Science, Al-Azhar University, Cairo, Egypt
每年涂布铜版纸和纸板的消费量约为4500万吨[1]。到2020年,全球纸包装市场预计将达到3070亿美元。涂层的主要目的是改善纸张或纸板的表面质量。 * H. M. El-Sherif 1埃及开罗国家研究中心聚合物和颜料系2埃及艾哈扎尔大学科学系化学系埃及开罗
quality improvement can take account of optical properties such as brightness, gloss or opacity, tactile properties such as smoothness, but, most importantly, printability and print image quality. The performance of coated paper, to a large extent, determines the image quality. Tolerable mechanical properties of paper coating are also indispensable for good end-use performance [1].
A typical pigmented coating consists of binder, pigment “providing the character of coating” and a solvent, often water. Coatings are composite materials with mechanical properties that depend, in a complex manner, on those of the polymeric binder, the pigment type, shape and size distribution and on inter-phase phenomena governing the transfer of stresses [2]. Although reduction in the coating price and opacity providing are the two motivations to add pigments to a binder latex, improvement in mechanical properties is another major key [3].
Moreover, the type of pigment plays a crucial role, for instance, when the clay was replaced by calcium carbonate, a strong interaction was observed between the latter and the styrene–butadiene polymer, even though the ductility and the in-plane mechanical strength were lessened [2]. The composite properties of coatings were approached in two ways, macroscopic and microscopic. Bulk properties of the coatings were measured including film thickness, grammage (the mass per unit area) and gloss. Mechanical properties such as tensile strength, ring crush and bursting strength are macroscopic properties [4].
Currently, nanocomposites are essential alternatives to conventional ones as they display noteworthy progress in modulus, dimensional stability, solvent resistance, low density, good flow, better surface properties and recyclability. This is due to the very large organic/inorganic interface which could alter the molecular mobility, the relaxation behavior and the consequential thermal and mechanical characteristics of the resultant nanocomposite [5]. The basic types of surface failure of a coated paper were described as base stock and coating layer failures. For failure in the coating layer, the internal bonding, provided by the binder, between the pigment particles determines the overall strength [6].
The mechanical properties of coatings are, to a great extent, determined by the properties of the binders. The binder properties depend, among others very much, on their glass transition temperature [3]. Accordingly, binders with a glass transition of around 20–39 °C should be used.
Acrylic binders have established momentous uses in paper coating for greaseresistant coating, oil and solvent resistance and permanent flexibility [7] and the inplane tensile strength and the elongation at rupture.