Partial substitution of nitrocellulose by polyurethane resins in flexographic ink concentrates

The properties of flexographic inks obtained by the partial replacement of nitrocellulose (NC) resin with different amounts of polyurethane (PU) resins were evaluated for the statistical planning of mixtures to develop an optimum ink formulation. The formulations were developed using a statistical tool and they were found to present properties predicted by the tool. The results indicate that the substitution of the NC resin with PU resins leads to increased resistance of the ink film to delamination. The system obtained with the partial substitution of NC with PU has higher lamination bond strength than the pure NC-based system. The ink films of the formulations NC-based and NC/PU-based were evaluated by spectroscopy UV–vis, both inks have similar transparency of greater than 95% above 575 nm. When exposed to water, milk, and UV light, ink surfaces showed similar behavior in the atomic force microscope, Fourier-transform infrared spectroscopy, and UV–vis analysis. However, ink formulations with higher PU contents underwent higher photodegradation. Other properties such as the viscosity ink, gloss, coating strength, color, adhesion, and blocking of the NC/PU-based ink film did not vary significantly when compared to those of the standard ink produced exclusively with NC resin.     

塑料水性凹印油墨附着性能的研究

采用合适的颜基比和分散剂制备了塑料水性凹印油墨基墨,用与基墨具有良好相容性的树脂溶液调稀基墨,添加各种助剂以改善油墨样品的印刷适性,探讨了颜基比、树脂溶液、助剂对油墨附着力的影响。结果表明:基墨中颜基比为3:1、分散剂为1.5%时油墨在PET和BOPP塑料表面均有较好的附着力,制备油墨时,使用50%的AZ-3808树脂溶液并添加1.5%异丙醇或1.5%润湿剂时,油墨在PET塑料表面具有较好的附着力,使用50%的1424树脂和1437树脂的混合溶液并添加1.5%异丙醇时,油墨在BOPP塑料表面具有较好的附着力。     

Influence of dispersing additives on the conductivity of carbon black pigment dispersion

The influence of dispersing additives on the electrical conductivity of carbon black pigments dispersed in an organic medium was studied. Two dispersing additives were examined in combination with two different carbon blacks, a conductive carbon black and a nonconductive one. These carbon blacks differ in the size of their aggregates and in the amounts of surface oxygen groups. Both of the additives form a monolayer when adsorbed on either of the pigment surfaces. FTIR studies showed that chemical bonding of one of the additives on the surfaces of both pigments had occurred. Conductivity decreases with increasing additive concentration, but in the case of the chemically bonded additive, the conductivity of the dispersion remained high even at higher additive loadings. This study helps in understanding the effects such additives have on the specific conductivity of composite materials that contain dispersed carbon black pigment particles.     

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.     

Film formation from pigmented latex systems: Drying kinetics and bulk morphologies of ground calcium carbonate/functionalized poly(n‐butyl methacrylate‐co‐n‐butyl acrylate) blend films

The drying kinetics and bulk morphology of pigmented latex films obtained from poly(n‐butyl methacrylate‐co‐n‐butyl acrylate) latex particles functionalized with carboxyl groups and ground calcium carbonate blends were studied. Latex/pigment blends with higher carboxyl group coverage on the latex particle surfaces dried faster than films with few or no carboxyl groups present. The latex/pigment dispersions also dried faster when there was more stabilizer present in the blend system because of the hydrophilic nature of the stabilizer. The net effect of increasing the pigment volume concentration in the blend system was to shorten the drying time. The bulk morphologies of the freeze‐fractured surfaces of the pigmented latex films were studied with scanning electron microscopy. Scanning electron microscopy analysis showed that increased surface coverage of carboxyl groups on the latex particles in the latex/pigment blends resulted in the formation of smaller pigment aggregates with a more uniform size distribution in the blend films. In addition, the use of smaller latex particles in the blends reduced the ground calcium carbonate pigment aggregate size in the resulting films. Scanning electron microscopy analysis also showed that when the initial stabilizer coverage on the latex particles was equal to 18%, smaller aggregates of ground calcium carbonate were distributed within the copolymer matrix of the blend films in comparison with the cases for which the initial stabilizer coverage on the latex particles was 8 or 36%. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2267–2277, 2006     

Influence of crystal size of Yellow 13-type pigments on optical and rheological properties of lithographic inks

Use of a modern diffractometer and detailed knowledge of the crystal lattice structure have improved ability to size crystals of CI Pigment Yellow 13-type pigments. This has enabled confirmation and refinement of correlations observed in earlier work between crystal sizes and optical and rheological properties of commercially available pigments in lithographic inks. The correlations indicate that the dispersion procedures used have produced inks in which the pigments exist substantially as individually dispersed crystals. The correlations also indicate that the crystals of the commercially available pigments are effectively perfect. An alternative explanation on the basis that the various pigments have similar degrees of aggregation and imperfection of crystals is also possible, but improbable due to the widely different compositions and sources of the pigments. Whether or not abietyl resin added to improve dispersibility of pigment remains on the crystal surfaces in inks has not been resolved.     

Use of effect pigments for quality enhancement of offset printed specialty papers

Nowadays, effect pigments are widely used in many printing industries. The colorful effects produced by light scattering of these types of pigments add an additional value to the prints and enhances the overall quality of color appearance. The aim of this study was to investigate the quality enhancement of printed specialty papers with various effect pigments in combination with offset inks. Four different effect pigments were used (one luster pigment‐EP1, two interference pigments‐EP2, EP3, and one multicolor pigment‐EP4) as well as two types of paper substrates (film synthetic paper and wood‐free paper). The effect pigments were overprinted on dried CMYK offset prints on both paper substrates. The following analysis were performed: scanning electron microscopy analysis of effect pigment particles, contact angles of papers and offset prints, Fourier transform infrared spectrocopy (FTIR), principal components analysis (principal components analysis (PCA)), and flop index analysis of overprinted effect pigments, and paper and print gloss. The results of the experiment indicate that effect pigments behaved differently on different printing substrates. From the FTIR and PCA, it was found that the different composition of effect pigments differently influence the behavior of these particles on the final prints. Effect pigments overprinted on offset CMYK inks on both paper substrates enhance print gloss, except interference pigment EP2 on film synthetic paper. It was also found that the ink color has the most pronounced influence on flop index, followed by the papertype and the type of effect pigment. Higher flop index was obtained at wood‐free paper, especially by overprinted pigment EP2. © 2012 Wiley Periodicals, Inc. Col Res Appl, 38, 168–176, 2013.     

油性颜料型彩色喷墨墨水的性能研究

以丙烯酸甲酯,甲基丙烯酸甲酯和丙烯酰胺为单体,经过自由基共聚,再经Hofmann降解反应,合成了带有胺基的丙烯酸酯类的共聚物。将该共聚物作为喷墨墨水中的连接料,达到增强颜料在墨水中的分散稳定性的目的。用红外光谱确定了酰胺基到胺基的转化。测定了带胺基的聚丙烯酸酯的连接料含量与墨水体系稳定性、沉降率的关系。带胺基的聚丙烯酸酯的连接料配制成的墨水,体系稳定性好,置于扫描电镜下观察,颜料具有较好的颗粒粒径和分布。     

喷墨打印机颜料型油墨的最新进展

喷墨打印技术是一种非接触式的数字印刷技术,它将数码技术与传统的印刷技术合二为一。用于喷墨印刷的染料型墨水通常表现出差的耐光性和耐水性,因此将颜料引进到喷墨油墨中以克服染料型墨水的缺点是必然趋势。为了在低粘度下保持颜料稳定的分散,性能优异的合成分散剂对于获得稳定的颜料分散体是必不可少的。本文介绍了水性喷墨油墨的组分及各组分作用,对喷墨油墨的生产技术、发展前景进行了展望。     

Syntheses of polymeric dispersants for pigmented ink‐jet inks

Drop‐on‐demand ink‐jet inks made from dyes usually show poor light fastness and poor water fastness. Therefore, many researchers have introduced pigments into ink‐jet inks to overcome the defects of dye‐based ink. Pigmented ink needs sophisticated technology which disperses the pigments stably in low viscosity. Thus, adequate dispersants are essential to achieve stable dispersions of pigments for ink‐jet inks. This study describes syntheses of dispersants, properties of formulations and comparisons of performance with an existing ink to assess their suitability for commercial application.     

Rheological Control of the Coffee Stain Effect for Inkjet Printing of Ceramics

The rheology of inkjet printing inks must be well controlled in order to be able to form small droplets. One solution is to use low volume fraction dispersed suspensions, but this leads to a common problem during drying called the coffee stain effect. It is caused by particle migration from the center to the edge of a drying drop and leads to nonuniform printed structures. This article describes an approach, to suppress the coffee stain effect by a sufficiently fast increase in viscosity after deposition. Due to the viscosity limitations during printing, inks with tailored rheology and drying behavior need to be developed. Ceramic inks were prepared and printed. First, a binder was added to study the influence of viscosity on printability and the coffee stain effect. Second, the use of a high vapor pressure solvent for faster drying was investigated. Eventually, an ink with the combination of binder and fast drying agent was prepared. This ink showed a considerable decrease in drying time as well as a rapid increase in viscosity after deposition and was suitable to completely suppress the coffee stain effect. Plateau‐like structures were achieved by adapting the drying temperature to permit particle movement to a certain degree.     

Adhesion improvement of UV-curable ink using silane coupling agent onto glass substrate

In order to enhance the adhesions of the UV-curable inks onto glass substrate, the silane coupling agents were added into the mixture of monomer and oligomer. The monomer, containing high functionality or surface tension could lead to a high cross-link density of the polymeric network and low adhesions of UV-curable inks. With the amount of ethyoxyls of ethoxylated trimethylolpropane triacrylate increasing, adhesions of the oligomers were improved. As the monomer concentration increased, the adhesion ability of UV-curable ink onto glass was decreased. The adhesion ability of UV-curable inks onto glass was increased via adding silane coupling agents. When the concentration of the silane coupling agents was more than 12%, the adhesion ability of UV-curable inks onto glass was decreased. Silane coupling agents (3-methacryloxypropyl) trimethoxy silane (KH570) and (3-aminopropyl) triethoxy silane (KH550) were more effective than (3-glycidoxypropyl) trimethoxy silane (KH560) in the inks under the same concentration. Video microscope and scraper fineness test revealed that the pigment particles declined with the increase of grinding times, whereas the adhesions of UV-curable inks were enhanced.     

Effect of process conditions on the properties of surface‐modified organic pigments encapsulated by UV‐curable resins

Aqueous dispersions of nanoscale organic pigments were successfully prepared via ball milling and ultrasonication. The dispersed organic pigments were encapsulated into UV‐curable resins via a mini‐emulsion technique. Critical factors that affected the dispersion and encapsulation stability were investigated. The encapsulated organic pigments were characterised with transmission electron microscopy, thermogravimetric analyses, Fourier Transform‐infrared spectra and zeta potential. The results clarified that the type of dispersing agent plays an important role in achieving maximal dispersion stability. Encapsulated organic pigments showed greater dispersion stability, and better wettability than the original pigments. Polyester tetra‐acrylate oligomer can stabilise the mini‐emulsion from diffusion degradation and inhibit phase separation with time. 1,6‐Hexandiol dimethacrylate was the monomer of choice for ink‐jet printing inks. Furthermore, it was found that monomer/oligomer and pigment/resin ratios were more influential and needed to be optimised. Thermal analysis, ultracentrifuge sedimentation and morphologies provided supporting evidence for the encapsulation of organic pigments into UV‐curable resins.     

A generalized criterion for rubber toughening: The critical matrix ligament thickness

The thickness of matrix ligament is shown to be the single parameter determining whether a polymer/rubber blend will be tough or brittle. The matrix ligament is defined as the region of the matrix between two neighboring rubber particles. Specifically, the ligament thickness is the surface-to-surface interparticle distance. When the average ligament thickness is smaller than a critical value, a blend will be tough; when greater, it will be brittle. In other words, a sharp brittle–tough transition occurs at the critical ligament thickness. This critical parameter is independent of rubber volume fraction and particle size, and is characteristic of the matrix for a given mode, temperature and rate of deformation. What is important is the matrix ligament, not rubber particles. The single matrix parameter explains the effects of phase morphology, rubber volume fraction, particle size, particle-size polydispersity, and particle flocculation on toughness.     

Titanium dioxide grafted with silane coupling agents and its use in blue light curing ink

To improve the properties of titanium dioxide particles and realise their firm anchorage in blue light curing film, three modified titanium dioxide particles were prepared by grafting 3‐(trimethoxysilyl)propyl methacrylate, 3‐aminopropyltriethoxysilane and hexadecyltrimethoxysilane. The surface changes of titanium dioxide particles after modification were characterised. The dispersion stability, photo‐polymerisation, rheological and mechanical properties of modified titanium dioxide blue light curing inks were investigated. Results showed that compared with native titanium dioxide, modified titanium dioxide particles were more appropriate for blue light curing ink. The particle sizes of the three modified titanium dioxide particles became smaller, their surfaces exhibited hydrophobicity, and the viscosity of the modified titanium dioxide inks decreased slightly. Of the three modified titanium dioxide particles, 3‐(trimethoxysilyl)propyl methacrylate‐ and hexadecyltrimethoxysilane‐modified titanium dioxide particles exhibited better dispersion stability in blue light curing ink. In particular, 3‐(trimethoxysilyl)propyl methacrylate‐modified titanium dioxide blue light curing ink showed the best photo‐polymerisation and mechanical properties, which indicated the participation of the pigment grafted by double bonds in the blue light curable polymerisation. Using modified titanium dioxide in blue light curing ink, the dry/wet rubbing fastness of the printed fabrics improved.     

Influence of chitosan posttreatment parameters on the fixation of pigment‐based inks on ink‐jet‐printed cotton fabrics

Cotton fabrics were digitally printed with pigment‐based black ink with an HP Desk‐Jet 880C printer. These ink‐jet‐printed fabrics were posttreated with chitosan samples for the fixation of the pigment‐based ink on the cotton. The influence of various parameters, including the molecular weight (MW), application method (pad–dry–cure vs pad–batch), concentration, and pH, on the degree of fixation (DF) of the pigment‐based inks was examined. The chitosan‐posttreated cotton samples were evaluated for their color strength, DF, color difference, and whiteness index values and their colorfastness properties. Chitosan samples with MWs of 150,000 and greater than 375,000 showed 100% (complete) fixation of the pigment‐based inks on the cotton fabrics. DF drastically decreased in the chitosan with an MW of less than 5000. Both the pad–dry–cure and pad–batch methods were found to be suitable for chitosan application onto ink‐jet‐printed fabrics. Chitosan with an MW of 150,000 showed 100% fixation at concentrations ranging from 0.3 to 1%. A further decrease in the concentration significantly decreased the fixation. High fixation values were achieved at acidic pH, whereas a neutral to alkaline pH resulted in poor fixation. The colorfastness properties for each parameter studied are also discussed. The posttreatment of the digitally printed cotton with chitosan was found to be very effective in fixing the pigment‐based inks. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Printability of functional inks on multilayer curtain coated paper

Printability of functional inks on multilayer curtain coated substrates was investigated. The inks represent those commonly used to produce solution processable electronic devices, such as organic transistors. The substrate, which combines sufficient barrier and printability properties for printed functional devices, was manufactured utilizing high speed curtain coating technique. The coating structure consists of a mineral pigment layer coated on top of a barrier layer. The combination of the two layers allows for controlling the absorption of ink solvents. By adjusting the thickness, porosity and surface energy of the top-coating the printability can be tuned for various functional inks. Focus was set on printing conducting silver and carbon inks, both with nano- and micrometer sized particles, as well as printing of an organic semiconductor, poly(3-hexylthiophene). The pore volume in the top-coating determined the spreading of the micrometer sized silver ink as well as the amount semiconductor per area required, whereas the pore size was the determining factor regarding penetration of the nano-sized silver ink. As a proof of concept hygroscopic insulator field effect transistors were printed on the multi-layer curtain coated paper using a custom-built roll to roll hybrid printer.     

Synthesis of ZnS–Mn nano-luminescent pigment for ink applications

In the present study, ZnS–Mn nano-luminescent pigments were synthesized, using co-precipitation method. Polyvinylpyrrolidine (PVP) surface modifier and Mn dopant concentrations were considered as affecting parameters. The luminescent ink was loaded with two different concentrations of pigments. The obtained ink was silk-screened on different types of fabrics mainly treated cotton, cotton and nylon. Structure, microstructure, luminescent properties of nano-pigments, inks and fabrics and also rheological properties of the inks were investigated. The results showed that the ceramic ink prepared with nano-luminescent pigment had high photoluminescence (PL) intensity. Moreover, the optimum concentrations of Mn and PVP for obtaining maximum PL intensity were found as 2 and 5 wt%, respectively. SEM images of fabrics indicated that nanoparticles were loaded, nonuniformly, on the fibers. The treated linen and nylon fabrics showed maximum and minimum PL intensity, respectively, due to ink penetration depth in the fabrics. Furthermore, washing fastness estimated for all fabrics was in the proper range.     

黑色硝化棉/乙醇油墨流变性的研究

研究了分散在硝化棉(NC)／乙醇油墨中的炭黑对油墨流变性的影响，通过Ostwald—Dewael，Mooney流变性模型分析了炭黑用量、分散剂类型及分散剂用量对黑色油墨粘度的影响，并测定了炭黑对NC的吸附等温线。     

Stability of pigment and resin dispersions in waterborne paint

The stability of a colloidal dispersion in a waterborne paint system, which consists of dispersed pigment and polymeric particles (dispersion or emulsion) along with a water-soluble acrylic polymer, was investigated. It was found that adsorption of appropriate ultrafine particles to the relevant particles could stabilize these particles against flocculation, leading to lower viscosity and yield value. The gloss and smoothness of the resultant films are notably improved. As the stability of the colloidal particles in an aqueous system is strongly dependent on the electrostatic effect, the effect was evaluated by measuring the ζ-potentials of the relevant colloidal particles. The ζ-potential is the electric potential on the outside of the surface layer, which includes the counterions around the particle. The ζ-potentials of a series of pigments in a solution of a water-soluble polymer were determined. By arranging the pigments according to their ζ-potentials, an order of basicity-acidity was established for pigments in a waterborne system, and the order was found to be different from that of solventborne systems, thought to be due to adsorbed counterions. After dispersing the pigment sufficiently with an appropriate polymer dispersant, ultrafine particles (of size under 0.05 μm) of lower refractive indexes were adsorbed to the surface of the pigments and polymeric particles. The adsorption layer of ultrafine particles can modulate the ζ-potentials of various colloidal particles to bring them into a certain range, so that the co-flocculation tendency between different colloids is remarkably diminished providing quite stable paint compositions by both electrostatic and steric hindrance effects.