Offset Printing Plate Research Articles

INDIRECT INK TRANSFER FOR OFFSET PRINTING, TAKING INTO ACCOUNT THE ROUGHNESS OF THE OFFSET PRINTING PLATE SURFACE

This article is devoted to the study of the influence of the surface roughness of an offset printing plate on the form-decal contact and deckle-printed material. Taking into account the deepening of micro protrusions of the surface roughness of the printing plate into the body of the deckle, which lead to additional displacements and deformation of the deckle, the amount of ink on the surface of the form is determined. The separation and transition of the paint layer in the contact zone has been studied. It has been established that the ink layer located in the free space of the roughness of the surface of the printing plate is also involved in the transfer of ink. The proposed method of indirect ink transfer in offset printing allows you to determine more accurate values of consumables in the design of printing processes, also predict the quality of printed prints, determine the runtime of printing plates, and correctly configure the printing machine before the printing process.

Quality assessment of offset thermosensitive printing plates

This article discusses the technological possibilities of assessing the quality of offset thermosensitive printing plates by studying the influence of the structural and physical properties of their construction layers, as well as the parameters of digital computer-to-plate recording on the quality of formation and reproduction of image elements. The article presents an original conceptual model for determining the integral quality indicators of printing plates, taking into account their structural and physical properties, a set of modern methods for evaluating the quality of offset printing forms is presented, such as evaluating the surface morphology of polymer registering layers and a substrate – a basis of the printing form; assessment of the adhesion of polymer layers of offset printing plates to the substrate surface, taking into account the influence of image recording parameters; investigation of the influence of the chemical state of the registering layers of offset plates on the adhesion of printing elements to inks; assessment of the influence of the processes of thermal action of laser radiation and the temperature gradient on the surface structure of the polymer layer of a thermosensitive plate and the accuracy of the formation of the quality of discrete image elements on printing plates.These researches are aimed at determining the relationship between the structural and physicochemical properties of offset thermosensitive plates and integral indicators of the reproduction quality of raster and line image elements in a digital recording system.

STUDY OF WETTING ON THE NON-IMAGE AREA OF OFFSET PRINTING PLATES BY AN ALTERNATIVE ISO-PROPYL ALCOHOL-FREE FOUNTAIN SOLUTION

In this study, an alternative aqueous isopropyl alcohol-free fountain solution for sheet-fed offset printing is prepared comprising 5 w/w% McIlvaine's buffer system for pH control, 0.3 w/w% Polysorbate 80 as a surfactant, 1 w/w% magnesium nitrate hexahydrate as a conductivity agent and 10 w/w% ethylene glycol mono-butyl ether as an additional wetting agent. The percentages of each composition are w/w% of active and then adjusted to 100 w/w% by adding distilled water. The contact angles of the obtained fountain solution on non-image areas of three common offset printing plates: CTP plate of Kodak, CTP plate of Huaguang Graphic Co. Ltd (China), and CTP plate of Mylan Printing Media Co. Ltd (Vietnam), range from 10° to 20°.The surface tension, conductivity, pH and viscosity were found to be 30.5 mN/m, 1.45 mS/cm, 4.8, and 1.05 x 10-2 g/cm.s, respectively. In comparison to the commercial fountain solution (KF – Trade Mark (China) containing isopropyl alcohol (IPA), the obtained fountain solution shows similar wettability on the non-image area of the offset printing plate whilst having similar physico-chemical parameters. The results indicate that ethylene glycol mono-butyl ether could be a potential substitute for IPA in fountain solution in offset printing, and the obtained fountain solution displays suitable properties for the offset printing process.

The sensitization effect of waste toner powder in the photocatalytic degradation of surfactant sodium dodecylbenzene sulfonate over immobilized TiO2–chitosan layer under UVC and solar irradiation

The application of dye sensitized photocatalysis for the degradation of surfactant in the model wastewater has been studied. The aim was to explore the possibility of the photocatalytic activity enhancement by introducing the waste toner powder in the photocatalytic films. The development and a partial characterization of the supported catalyst were described within this study. Waste toner and commercial TiO2 powder (AEROXIDE® P25) were integrated within the matrix of chitosan molecules as a thin layer films. The developed films contain the high amount of the TiO2 (approx. 90%) which structure appeared to be intact. The efficiency of the photocatalytic films for the oxidation of the anionic surfactant dodecylbenzene sulfonate (SDBS) has been evaluated. Preliminary experiments were performed in an annular batch reactor using UVC lamp. Photocatalytic films were supported on the glass, stainless steel and waste offset printing plates. Support was made in a form of plates or rings. Further experiments were performed under artificial and natural solar irradiation whereby photocatalytic films were fixed at the bottom of reaction cell (boat shaped flow reactor). In order to estimate the reaction rate constant for SDBS degradation over irradiated photocatalytic films and to evaluate the effects of photon absorption under different irradiation conditions, a detailed kinetic model was developed. The sensitization effect of the components in toner powder due to the visible light absorption for the photocatalytic oxidation of SDBS under solar irradiation was quantified.

Evaluation of effective models of offset CTP plate aluminium oxide surface roughness characterisation

In this study, three different approaches for characterisation of printing plate's non-printing elements surface structure and roughness were compared: stylus profilometric method, AFM, method and software (indirect), SEM image-based profilometry. The comparison was made to evaluate the possibility of utilising the different methods for characterisation of CTP offset printing plate surface roughness. The direct profilometric measurements involved the use of stylus profilometer visual analysis were made using AFM device and for the indirect approach, the Gwyddion software, for analysis of single and stereo SEM images and calculation of standard profilometric parameters, was used. The results of this study demonstrate that it is possible to obtain profilometric parameters from the analysis of AFM and SEM micrographs with appropriately calibrated grey scale intensity distribution and that the values of the parameters are comparable to those obtained by contact stylus profilometry. The results of this comparative study indicate that profilometric 2D direct stylus method is more applicable when larger areas tend to be measured, while the indirect image-based 3D profilometry is a valuable and efficient tool for characterisation of various surface's topographies on micron scale sample areas.

Evaluation of effective models of offset CTP plate aluminium oxide surface roughness characterisation

In this study, three different approaches for characterisation of printing plate's non-printing elements surface structure and roughness were compared: stylus profilometric method, AFM, method and software (indirect), SEM image-based profilometry. The comparison was made to evaluate the possibility of utilising the different methods for characterisation of CTP offset printing plate surface roughness. The direct profilometric measurements involved the use of stylus profilometer visual analysis were made using AFM device and for the indirect approach, the Gwyddion software, for analysis of single and stereo SEM images and calculation of standard profilometric parameters, was used. The results of this study demonstrate that it is possible to obtain profilometric parameters from the analysis of AFM and SEM micrographs with appropriately calibrated grey scale intensity distribution and that the values of the parameters are comparable to those obtained by contact stylus profilometry. The results of this comparative study indicate that profilometric 2D direct stylus method is more applicable when larger areas tend to be measured, while the indirect image-based 3D profilometry is a valuable and efficient tool for characterisation of various surface's topographies on micron scale sample areas.

Offset Printing without Isopropyl Alcohol in Damping Solution

Alcohol free “wet” offset technology is important not only for the sake of printers but for a stronger, more profitable business. The optimization of automatic offset printing system for the environmentally friendly dampening components via free alcohol and filtration procedures is a further milestone of the classical offset technology environmental approach.Offset printing, also named “wet” offset, uses dampening solution in order to keep non-printing elements as a hydrophilic on the surface of offset printing plate. So fountain solution is a part of its process. Generally it is composed by water and around of 8-10% isopropyl alcohol as a surface active agent improved wetting. However, there are inherent issues with this process, such as negative environmental impact, health hazardous, complex press operations and waste water and chemical regulations. Isopropyl alcohol used in water solution in offset printing has negative influence as: part of it vaporizes to form volatile organic compounds that pollute the working environment, also toxic and flammable. Measured by volume IPA is the most significant air pollutant in the offset printing companies. In the common ecology savings conditions there are alternative ways to reduce or even fully IPA-free printing, lowering costs and risks for health and safety the environment.In web offset printing are several possibilities to apply alcohol free dampening solution. In this study for the CSWO (Cold Set Web Offset) printing it was applied fully alcohol free solution with specially developed additive, compatible to individual tap water properties. In addition here was used ceramic filtration system in order to prevent fast contamination and also permit longer intervals between changing the fountain solution and keeps it clean during the long period. So in this way we achieved having stable printing process without any problems.

Influence of Parameters of a Printing Plate on Photoluminescence of Nanophotonic Printed Elements of Novel Packaging

In order to produce nanophotonic elements for smart packaging, we investigated the influence of the parameters of screen and offset gravure printing plates on features of printed application of coatings with nanophotonic components and on parameters of their photoluminescence. To determine the dependence of luminescence intensity on the thickness of solid coating, we carried out the formation of nanophotonic solid surfaces by means of screen printing with different layer thickness on polypropylene film. The obtained analytical dependencies were used to confirm the explanation of the processes that occur during the fabrication of nanophotonic coverings with offset gravure printing plates. As a result of experimental studies, it was determined that the different character of the dependency of total luminescence intensity of nanophotonic elements from the percentage of a pad is explained by the use of different types of offset gravure printing plates, where the size of raster points remains constant in one case and changes in the other case, while the depth of the printing elements accordingly changes or remains constant. To obtain nanophotonic areas with predetermined photoluminescent properties, the influence of investigated factors on changes of photoluminescent properties of nanophotonic printed surfaces should be taken into consideration.

Discussion on Application of 3D Printing Technology in Package Printing

The principle of 3D printing technology is based on the basic principle of ink-jet printing. The application of 3D printing in packaging printing is discussed, including printing history, development present situation, the principle, equipment, the advantages and disadvantages of 3D printing. The application of 3D printing in digital printing machine manufacturing and in offset printing plate making and screen plate making is studied. This paper is of great significance for the transformation of the printing industry.

Offset Printing Plate Quality Sensor on a Low-Cost Processor

The aim of this work is to develop a microprocessor-based sensor that measures the quality of the offset printing plate through the introduction of different image analysis applications. The main features of the presented system are the low cost, the low amount of power consumption, its modularity and easy integration with other industrial modules for printing plates, and its robustness against noise environments. For the sake of clarity, a viability analysis of previous software is presented through different strategies, based on dynamic histogram and Hough transform. This paper provides performance and scalability data compared with existing costly commercial devices. Furthermore, a general overview of quality control possibilities for printing plates is presented and could be useful to a system where such controls are regularly conducted.

Мас-спектрометричний аналіз проміжних елементів друкарських форм плоского офсетного друку

Was explored impact of the printing process on change of components of hydrophilic film of the non-printing elements on the offset printing plates. The influence of printing contact to replace components hydrophilic film non-printing elements of monometallic offset printing plates with moisture.Was explored the character of processes losing elements of their properties during the printing process, which is characterized by a gradual decrease in the number hydrophilic substances oxide film on the non-printing elements in physico-chemical and physico-mechanical impact printing environment.Determined the necessity for experimental research to create the optimum operating conditions and environment printing contact, allowing maximum identity imprints during print run.

Ultra-fast photo-patterning of hydroxamic acid layers adsorbed on TiAlN: The challenge of modeling thermally induced desorption

Long-chain n-alkyl terminated hydroxamic acids (HA) are used for the modification of titanium aluminum nitride (TiAlN) surfaces. HA coatings improve the hydrophobicity of this wear resistant and industrially relevant ceramic. Therefore, HAs with different structural properties are evaluated with respect to their wear resistance and their thermal desorption properties. In order to find new coatings for rewritable offset printing plates, the changes in the surface polarity, composition, and morphology are analyzed by contact angle measurements, X-ray photoemission spectroscopy (XPS), and scanning force microscopy (SFM), respectively. The results are referenced to the strongly bonding molecule n-dodecyl phosphonate (PO11M), which has been used for surface hydrophobization before but proved difficult to remove due to the high laser outputs required for thermal desorption. It is found that for certain HAs, an equally good hydrophobization compared to PO11M can be achieved. Contact angles obtained for different hydroxamic acid coatings can be correlated to their modes of adsorption. Only for selected HA species, resistance to mechanical wear is sufficient for further investigations. Photo-patterning of these hydroxamic acid layers is achieved using a high energy IR laser beam at different energy inputs. Fitting of the obtained data and further evaluation using finite element analysis (FEM) calculations reveal significantly reduced energy consumption of about 20% for the removal of a specific hydroxamic acid coating from the ceramic surface compared to PO11M.

Porous Polymer Membranes via Selectively Wetted Surfaces

Here, we show that porous polymeric membranes can be prepared using the principles of offset printing: an offset printing plate is structured into hydrophobic and hydrophilic regions with the help of photolithography and is selectively wetted with a solution of calcium chloride in water at the hydrophilic regions. Then, a polymer solution (poly(methyl methacrylate) in chloroform) is applied to this surface and forms a hydrophobic layer that is structured by the aqueous droplets. Deviating from standard offset printing, this layer is not transferred to another surface in its liquid state but is solidified and subsequently is separated from the printing plate. The thickness of the polymer film is chosen in such a way that the aqueous droplets on the surface protrude from the film. Thus, we obtain polymer membranes with pores in the size of the protruding aqueous droplets. These membranes are then characterized by the filtration of model dispersions.

Вплив друкарського контакту на зміну мікрогеометрії елементів друкарської форми

Проведено дослідження впливу процесу друку на мікрогеометрію поверхні друкувального і пробільного елементів монометалевих форм плоского офсетного друку із зволоженням.

Changes in the surface roughness of aluminium oxide (non-printing) areas on offset printing plate depending on number of imprints

A printing and non-printingsurface structure of the offset printing forms are key factors in maintaining the conventional offset printing. The main characteristics of the surface are: physical and chemical structure, surface tension and surface roughness. Surface topography is one of the critical factors which could cause the instability in the quality performance and the durability of the printing forms. During the printing process these characteristics change and directly influence the print. Performed investigations are based on the fact that the changes in physical-chemical properties of the non-printing areas as well as the changes in the surface micro structure of the printing forms directly influence the quality of the reproduction. In this paper, the behaviour of non-printing elements of a thermal CTP plate developed in a fresh developer and used for a print run of 123.000, 177.000 and 300.000 copies on a web offset heat-set printing press has been investigated. Investigation made in a paper showed that high depth of focus SEM (Scanning Electron Microscope) can provide detailed topographical information about the surface, but cannot provide quantitative topographical information. Due to this fact, the printing forms have been also ob-served and analysed before and after the print run by a mechanical stylus profilometer. The investigations reveal the appearance of the physical changes as well as the geometrical ones. As a result of these changes, the influence of a fountain solution on the printing form may also vary, as well as the balance between the ink and the fountain solution during the printing process.

Influence of the Print Run on Silver Halide Printing Plates

The most common printing technique today is lithography. The difference between printing and nonprinting areas on a printing plate is accomplished by opposite physical and chemical properties of those areas (MacPhee, 1998). The printing areas are made of photoactive layer that attracts oil and chemical substances with oil solvent – printing inks. The nonprinting areas are made of aluminium-oxide which attracts water based substances – the fountain solution.There are many of various types of photoactive layer which are used for production of offset printing plates, among others is silver halide layer. The usage of the silver halide technology in the graphic reproduction is not a novelty. The filmmaking phase is based on the usage of the silver halide as the photographically active ingredient, for in-stance, AgBr (silver bromide). The new, digital plate making technology (Computer to Plate, CtP) eliminates the filmmaking phase and therefore enables control of the printing plate’s exposure made by computer. CtP technology eliminates the filmmaking phase, but it also results with the reduction of needed material quantities and required time for the production (Limburg, 1994; Seydel, 1996).In this paper the basis of the graphic reproduction by using the silver halide digital printing plates was described. The changes of the AgX copying layer and the surface of the aluminium base in the printing process have been observed. The surface characteristics were determined by measuring the relevant surface roughness parameters. In addition, measurements of coverage values on the prints, detailed at smaller print run, were conducted.Results showed that surface changes on the printing plate are changing during printing process and that these changes influence transfer of the printing ink on the printing substrate. These measurements proved to be of great interest in the graphic reproduction as they enable us to determine consistency of the printing plates during the printing process, to predict the endurance as well as to define the print run which will result with optimal quality prints.

Fabrication and Application of TiO2‐Based Superhydrophilic–Superhydrophobic Patterns on Titanium Substrates for Offset Printing

A fabrication process for superhydrophilic-superhydrophilic patterns on titanium substrates prepared through a combination of an ink-jet technique and site-selective decomposition of a self-assembled monolayer (SAM) by a TiO(2) photocatalyst under UV irradiation is described. We demonstrate that the prepared titanium substrate is applicable as an offset printing plate with high resolution (133 and 150 lines per inch). Furthermore, the superhydrophilic-superhydrophobic patterns on the substrate can be deposited repeatedly after elimination of the patterns by photocatalytic decomposition of TiO(2) under UV irradiation. A second printed image with the renewed substrate showed no significant difference in image quality compared with the initial image.

The Odyssey of a Polymer Chemist in Switzerland

A personal survey of some of the polymer-related work which I had the chance to carry out in Ciba-Geigy's Central Research and in the polymer departments of Ciba SC, Vantico and Huntsman is given, including a few short comments on the eventful history of the former Ciba-Geigy Central Research and Polymer Division. In the early 1970s, high-temperature-stable aromatic [polyamide – polyimide] block copolymers and the relatively easy processable bismaleimides as high-temperature thermoset materials were the dominant theme. Work on photocrosslinkable DMI polymers which ultimately led to the development of a non-silver graphic film and a presensitized negative offset printing plate was pursued at the Centre de Recherche Marly. In the field of epoxy resin chemistry, 'latent' hardeners, featuring a relatively long pot-life at room temperature and a short cure cycle at the processing temperature, were devised in the form of benzyl-sulfonium salts and imidazole-functionalized microgels. Ciba-Geigy's polymer division has pioneered the development of liquid, photoimageable soldermasks with it's Probimer® range of products. Here binderpolymers constitute the main components of the complex formulation recipes. High molecular weight polymers carrying acryloyl and carboxyl functional groups were synthesized for this purpose and have found commercial application in new soldermask generations.

Formation and Defining the Different Aluminium Oxide Microstructures in Alkaline Solutions

The formation of different aluminium oxide microstructures on the offset printing plate during the plate making process influences the plate’s ability to adsorb and repel fluids. Adsorbing and repelling of the fountain solution and ink during the offset printing process have major influence on the plate’s stability and print quality. The aim of this research was to define the micro structural changes in the aluminium oxide layer during the plate making process, their influence on the surface free energy of the oxide, as well as contact angles of the adsorbed fluids.

B217 オフセット印刷における湿し水供給自動化に関する研究

In this paper, the correlation between the amount of dampening water on an offset printing plate and the intensity of speckle patterns generated on the plate is examined by experiment and numerical simulation. In experiment, speckle pattern observation is performed for two different conditions that the plate is at rest and dynamically move attached to a rotating cylinder to evaluate the feasibility of speckle intensity method in offset printing system. In numerical simulation, time variation of speckle intensity is simulated with the model of the distribution of dampening water on an offset printing plate, considering the reflection factors on water surface and the printing plate. From the results, it is seen that the speckle intensity method has usability on dynamic condition and speckle intensity depends on observation angle.