Synthesis and characterization of poly[(methyl methacrylate)‐co‐(methacrylic acid)] for a UV‐sensitive aqueous base developable lithographic plate

Syntheses of the copolymers of methyl methacrylate and methacrylic acid were carried out by free radical chain polymerization in the presence of benzoyl peroxide (BPO) as an initiator. The effects of the monomer ratio and polymerization time on the averaged molecular weights, polydispersity index, and glass transition temperature were investigated. FTIR and NMR were used for functional group characterization, GPC for average molecular weights and the distribution, elemental analysis for CHO content, and DSC for the glass transition temperature. The copolymers were mixed with tripropylene glycol diacrylate (TPGDA) and trimethylol propane ethoxylated triacrylate (TMPEOTA), 2‐hydroxy‐2‐methyl‐1‐phenyl‐propan‐1‐one (Darocur® 1173) and benzophenone (Darocur® BP) with anthraquinone for visibility of images. The photosensitive coating was spin‐coated onto the anodized aluminum plate on which a thin film was formed. The wet film was then coated with PVA solution as an oxygen barrier layer. The plate assembled with a control wedge and a black color separation film was exposed to UV radiation at different exposure times. The plate was developed in a dilute alkaline developer. The resulting plate was evaluated for its reproduction properties in terms of surface properties (hydrophilic/hydrophobicity) by contact angle measurement of image/nonimage areas, resolution by microline, tone reproduction, and adhesion tests. The article describes the results of the syntheses, characterizations, and uses of the copolymer as a binder of a negative, lithographic printing plate. The present lithographic printing plate is good for a medium viscosity printing ink to produce medium printing quality on uncoated paper. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1829–1837, 2002     

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.     

酰胺改性氢化蓖麻油在平版印刷油墨中的应用研究

通过试验,在传统平版印刷油墨体系(松香改性酚醛树脂、醇酸树脂)中添加酰胺改性氢化蓖麻油,考察其对油墨流动性及应用性能的影响。     

Tailoring the properties of deposited thin coating and print features in flexography by application of UV-ozone treatment

Printed functional materials are a rapidly growing area of interest for low-cost high-speed device manufacture with flexographic printing seen as a route to achieving this. The relationship between surface tension of the ink and surface free energy (SFE) of the photopolymer plate is a key for optimum performance. However, traditional methods of surface tension modification of the ink/coating often cannot be employed for functional inks. In this research, rapid, permanent modification of flexographic printing plate’s SFE is achieved through controlled UV-ozone treatment, and the effects of the treatment on the polar and dispersive component of SFE are analyzed by Fourier transform infrared attenuated total reflectance spectroscopy, swelling experiments, and roughness measurements. Printing trials using the modified printing plates reveal improved print uniformity and control of deposited ink layer thickness, as well as improved print features—particularly track and pad junctions which can be problematic for printed electronic applications. The ability to rapidly tailor printing plate SFE is of benefit to all volume printing applications. Furthermore, it is of critical importance for functional printing and printed electronics where surface tension of the ink is determined by the functional material and chemical modification is not possible or desirable.     

多孔介质中受限层流冲击射流的流动与换热特性

基于两区(two-domain)模型采用基于预处理的时间推进法对铺设有多孔介质层的恒温平板在受限层流冲击射流作用下的流动与换热特性进行了研究,其中多孔区域动量方程采用Brinkman-Forchheimer拓展Darcy模型,能量方程则采用局部热平衡(LTE)模型,并对porous/fluid交界面切应力跳跃条件对多孔介质冲击射流的影响进行了分析。流体的控制方程采用基于密度的有限体积法来求解,并针对于多孔区域低速流动特点采用相对应的预处理矩阵来消除控制方程的刚性。还对Reynolds数、孔隙率、Darcy数、热导率比、多孔介质层厚度等参数的变化对流动结构及换热特性的影响进行了分析。研究结果表明,在目前的计算条件下,在其他参数一定时,Reynolds数、孔隙率对通道内流动结构的影响有限;Darcy数、多孔介质层厚度则对流动结构的影响很大;上述参数对受冲击平板的总体换热性能均有明显的影响。在受冲击平板上铺设适当厚度的高渗透率、高热导率的多孔材料能有效地增强换热性能。     

Crystal morphology of organic pigments and rheology of dispersions in ink and paint media

The purpose of this work is to establish relationships between physico-chemical character of pigments and rheological behaviour of dispersions under steady shear conditions. It has been found that the approximately cube-shaped crystals of CI Pigment Yellow 13-type pigments disperse substantially as individual crystals in (highly viscous) lithographic ink media; strength of structure and plastic viscosity relate simply to number concentration of crystals and area of the pigment/medium interface, respectively. Interpretation of data for dispersions of Red 57.1 pigments in similar media is complicated by persistent face-to-face aggregation of their rectangular plate-shaped crystals. In dispersions of metal-free monoazo pigments (Yellows 1 and 74, Reds 3 and 112) in decorative paint media (relatively low viscosity) strength of structure shows a markedly increased dependence on pigment concentration above a critical concentration. This concentration is different for each pigment and is determined primarily by crystal shape, the less cube-shaped the crystals the lower the critical concentration. Plastic viscosity is dependent upon area of the pigment/medium interface and thickness of adsorbed layer of paint medium.     

Structure of polymer within the coating: an atomic force microscopy and small angle neutrons scattering study

Synthetic latex is widely used as a binder in waterbased paints. Upon dehydration of the dispersion, latex particles are brought into contact with mineral pigments: this process results in coating structuration and consolidation. This composite layer is described as a porous mineral structure, whose pores are covered by latex particles. Therefore, it is of fundamental interest to study the ordering of binder particles in the coating, and the wetting of pigments by polymer particles, toward understanding properties of coating such as: optical properties, adhesion, cohesion, sensitivity to water, etc. In this regard, we have used small angle neutron scattering and atomic force microscopy to study the ordering, the spreading, and the adhesion of latex particles on calcium carbonate within the coating. We discuss the structure of the coating.     

Preparation and properties of alcohol-resistant thermal transfer printing inks for multifunctional label printing via physical blending of resins

Due to the rise of the logistics industry and the widespread use of ink labels, problems such as the narrow operating temperature range of ink, poor alcohol resistance, and insufficient scratch resistance need to be solved urgently. In this work, creates alcohol-resistant thermal transfer inks by mixing polypropylene chloride (VP-365) and epoxidized hydrogenated bisphenol A (P) resin and incorporating them into the ink formulation. The synthetic ink has a lower glass transition temperature (118.2°C), allowing the ink to print at lower temperatures. It has small wetting angles (68°, 63°, 58°, 46°, and 40°) and a large adhesion force (10.44 – 14.4 N) for different labels. Further, to evaluate the printing performance of the ink, the ink was scratched under 1000 g pressure and in the environment of isopropyl alcohol to evaluate its printing performance. The produced ink has high scratch resistance (300 times) and good alcohol resistance (140 times). Moreover, the developed ink showed good printability, printing media versatility, high adhesion, and excellent alcohol resistance. The synthesis method is facile and cost-effective, which paves a novel way towards high-performance ink printing and thermal transfer technology industries.     

Surface and adhesion changes of atmospheric barrier discharge-treated polypropylene in air and nitrogen

Oriented polypropylene treated by atmospheric barrier discharges in air and nitrogen was investigated using several techniques: contact angle measurements, ATR-FT-IR spectroscopy and two adhesion tests based on the stripping of an applied ink layer. The activation in an air discharge was found to be much weaker compared to the activation in industrial grade nitrogen, particularly with respect to adhesion. The adhesion was found to be much better in nitrogen in spite of the common use of air in industrial 'corona discharges'. A new 'abrasive shear-stripping' (AS) test for ink coating adhesion was designed and performed. It was shown that the AS test was much more sensitive than the classical adhesive tape test and was sensitive enough to monitor ageing and overtreatment. The contact angle measurements did not correlate completely with the adhesion properties and could not monitor the overtreatment, while the ATR-FT-IR technique indicated changes just for overtreated foils.     

硅烷在喷墨打印相纸涂层中的应用研究

本文用硅烷偶联剂对氧化铝颗粒进行了改性研究,找到了使氧化铝分散液产生触变特性的条件,不但提高了产品的表观质量和涂层的湿膜强度,增大了涂层的吸墨量,还大幅度降低了成本。     

紫激光CTP版材的感光组成物

从Drupa2000紫激光二极管推出使用至今,紫激光CTP技术迅速发展。紫激光CTP版材属于光聚合型板材,其感光层由成膜树脂、聚合单体、增感色素和引发剂等成分组成。本文主要介绍了富士、柯尼卡、柯达等几家大公司专利文献所涉及的应用于紫激光CTP版材的感光成像组成物,希望为国内同行开发相关版材提供一些借鉴。     

Influence of Work of Adhesion on Dissolution Rate in Binary Solid Systems

In powder mixtures, the interactions between the particles are determined by the forces of adhesion and cohesion. The size and the specific surface area of the particles are also determinative factors in the interparticle interactions.

The aim of the present work was to investigate the surface properties of different physical mixtures of meloxicam (ME) and find a possible relation between surface properties and dissolution of physical mixtures. The contact angle, surface free energy, polarity, work of adhesion, and work of cohesion of the drug, the carrier, and their physical mixtures were calculated.

ME samples with different particle sizes were investigated without the carrier and in two different ratios with mannitol. A smaller (micronized) particle size without the carrier did not improve the dissolution of the drug. However, with the ideal particle size of the drug (ME2) and the ideal ratio of ME and mannitol (1:10), total dissolution of drug was achieved. In this case, mannitol functioned as a core covered with a monolayer of ME particles. The contact angle, the surface free energy, the polarity, and the work of adhesion can be used as critical parameters to characterization of a powder mixtures and determination of optimum dissolution profile.     

喷墨打印在水转印上的应用及工艺研究

将喷墨打印应用在水转印当中,用水性油墨代替油性油墨,并就其在铝材上的转印工艺进行研究。考察了铝材表面处理后对水转印后粘接性的影响,水温和过渡层配方对转印效果的影响。结果表明,铝材表面经过磷化处理后,用丙烯酸金属涂料涂覆,可提高水转印后粘接性,转印时水温升高,过渡层配方中硝化棉增多,随R-2树脂减少,以及溶剂的减少都会使伸长率下降。初始接触角随着司班80加入而逐渐降低,而接触角的变化率则显著增大,提高了打印质量。     

Low-molecular-weight materials on corona-treated polypropylene

—ESCA, wettability measurements, SEM, weight-loss determinations, and an ink adhesion test were used to characterize low-molecular-weight oxidized materials (LMWOM) formed during the corona-discharge treatment of polypropylene film. Water-soluble LMWOM is readily formed by scission processes occurring during corona treatment. The presence of water-soluble LMWOM complicates the interpretation of wettability-based measurements of corona effectiveness. Surface roughening on corona-treated polypropylene is caused by the interaction of LMWOM and water in a high-relative-humidity environment. LMWOM does not necessarily form a weak boundary layer that hinders subsequent adhesion of ink to the corona-treated film.     

The role of the surface free energy in the selection of a suitable excipient in the course of a wet-granulation method

Pellets containing metronidazole were produced in a centrifugal granulator, with hydroxypropylcellulose (Klucel LF®) as binding agent, and corn starch, microcrystalline cellulose (Vivapur 101®) and lactose as excipients. The wettability of the pharmaceutical powders was assessed by means of contact angle measurements, and the dispersive and polar surface energies were determined. The spreading coefficients, the work of adhesion and the work of cohesion were calculated and correlated with the pellet properties (friability, bulk and tapped density, and porosity). The aim was to investigate the role of the surface free energy of one- and two-component powder compositions in pellet production. The interactions between the particles were found to be connected with the measured pellet parameters. It was concluded that, in the course of the growth of the pellets, the particle sizes of the pharmaceutical powders and the interactions between them are important. If the work of cohesion of the binder is lower than the work of cohesion of the substrate and the work of adhesion, then the optimal amount of the binding agent is that which coats the particles uniformly in minimal quantity and in continuous layer.     

Ink-lift-off during offset printing: a novel mechanism behind ink–paper coating adhesion failure

This paper reports on a special pilot coating and industrial printing trial designed to gain fundamental knowledge on ink adhesion failure on coated papers. We found that ink adhesion failure resulted in white spots without ink on the paper, referred to as uncovered areas and these spots gave print mottle problems. The white spots were due to two fundamentally different types of ink adhesion failure. One is the well-known ink rejection, which simply means that ink is not transferred to the surface. The other is a new type of ink adhesion failure, confirming a previous hypothesis suggested from laboratory observations. We refer to this as ink-lift-off adhesion failure, meaning that ink initially deposited on the paper surface becomes lifted off from the surface in a subsequent print unit. Adhesion failure by this mechanism was seen to occur more frequently than failure due to the well-known ink rejection.     

聚钛硅氧烷凝胶与铝、铁界面粘接机理

用扫描电镜SEM和X射线能量散布分析EDAX技术研究了聚钛硅氧烷 (PTS)与铝、铁基材界面 ,结果发现了PTS与铝界面有良好的结合 ,该结合机理被认为是铝氧化物与PTS产生化学反应 ,形成互渗层的结果 ,随热处理温度提高互渗层厚度增加 ;与上述结果相反 ,PTS与铁基材界面没有明显的化学结合 ,随热处理温度提高界面缺陷增加     

A new technique for evaluating ink–cellulose interactions: initial studies of the influence of surface energy and surface roughness

Ink–cellulose interactions were evaluated using a new technique in which the adhesion properties between ink and cellulose were directly measured using a Micro-Adhesion Measurement Apparatus (MAMA). The adhesion properties determined with MAMA were used to estimate the total energy release upon separating ink from cellulose in water. The total energy release was calculated from interfacial energies determined via contact angle measurements and the Lifshitz–van der Waals/acid–base approach. Both methods indicated spontaneous ink release from model cellulose surfaces, although the absolute values differed because of differences in measuring techniques and different ways of evaluation. MAMA measured the dry adhesion between ink and cellulose, whereas the interfacial energies were determined for wet surfaces. The total energy release was linked to ink detachment from model cellulose surfaces, determined using the impinging jet cell. The influences of surface energy and surface roughness were also investigated. Increasing the surface roughness or decreasing the surface energy decreased the ink detachment due to differences in the molecular contact area and differences in the adhesiom properties.     

The effect of corona and ozone treatment on the adhesion of ink to the surface of polyethylene

Low density polyethylene sheet was subjected to treatment by corona discharge in oxygen, nitrogen, helium and argon; in addition some sheets were treated with ozone gas. The bond strength between two similarly treated sheets was then measured using a commercial flexographic ink as an adhesive. The results showed that although surface oxidation improved both the ink adhesion and the wetting properties of polyethylene it is not a necessary prerequisite for good bonding. When the sheet was subjected to electrical discharge in nitrogen, argon or helium, considerable enhancement of ink adhesion was obtained without any detectable change in the surface chemistry of the polymer. The results indicate that ink adhesion after treatment in various gases follows closely the trends established previously in corona-induced autohesion of polyethylene. This suggests that the mechanism of bonding is similar in the two cases.     

Pollution preventing microemulsion inks

Pollution caused by the clean up of lithographic printing presses is a major problem faced by the printing industry. This paper explores alternate ink systems where the use of hydrocarbon solvents and volatile organic compounds (VOCs) for clean up is eliminated. The ink under consideration is a microemulsion, which can be emulsified in plain water-the property that can be used for its cleanup from presses. Furthermore, the washing is a completely physical process with no chemical reaction occurring thereby eliminating any salt streams. The ink washing commences in the form of tiny jets of water-soluble material vigorously coming out at the interface of the microemulsion ink drop and the wash liquid. Spontaneous emulsification is therefore proposed as the mechanism of washing. This paper discusses the ink formulation, its properties, and a model for spontaneous emulsification to explain its washing. The theoretical work is supported by experimental results.