Dissertations / Theses on the topic 'Offset Printing Inks'

<p>This licentiate thesis comprises two complementary studiesdealing with the sheet-fed offset printing of paper. The firststudy addresses the further development of a practical methodto acoustically monitor and analyse the film splitting ofoffset inks. This method was tested on laboratory printingequipment, specifically monitoring the continuous ink splittingin the nip of an IGT ink distribution unit and the short-timeink splitting in the inked print disc-paper nip of the printingunit of an ISIT instrument. The study verified that the inksplitting component of the acoustic signal contributes to thehigher frequency range (10-20 kHz) of the audible spectrum, andcan thus be separated from the lower frequency machine noise.Furthermore, the film splitting component is sensitive tochanges in the ink and printing conditions, thus enabling itsuse in probing the fundamental mechanisms occurring during inktransfer and also suggesting its applicability fornon-intrusive monitoring of industrial printing presses. Anincrease in film thickness during ink distribution correspondsto an increased acoustic power, with the exception of very lowink amounts, which give reduced acoustic emission due to alubricating effect. The effect of the presence of fountainsolution was simulated by adding emulsion-forming, butnon-evaporative, ethylene glycol. This produces an increase inacoustic power at low amounts, due to resistance to glycol dropdeformation, followed by a decrease at higher amounts owing toexcess glycol lining the rolls. During test printing on paper,increasing ink amounts also display an increased acousticresponse.</p><p>The second study further developed a theoretical model toexplain and predict the evolution of ink tack in terms of inksetting directly after offset printing on coated paper. Asmeasured by the ISIT, the tack of the printed ink rises duringshorter time periods, attains a maximum, and then falls atlonger times. The proposed model described how the ink tack,characterised by the impulse during disc pull-off, dependsdynamically on the viscoelastic properties of the ink, thecontact with paper and disc, and the flow geometry. The inksetting was modelled as a diffusion-limited transport of theoil vehicle through the ink film and into the pores of thecoated paper. The coupling of the tack and setting models,compared to the ISIT experimental measurements, then provided adiffusion coeffcient for ink setting during the tack riseperiod. This coeffcient decreases with time, and increasinglyrapidly with decreasing ink amounts due to theconcentration-dependent diffusion. For an accurate descriptionthe elasticity and adhesion effects also have to be considered,at least for explaining the tack fall period.</p>

<p>During a make ready in a web offset press it is important to produce as little waste as possible. Reducing the amount of waste yields savings of both time and money. One way to do faster make ready is to preset the ink keys of the press before it is started. </p><p>This diploma work, carried out at Sörmlands Grafiska Quebecor AB in the city of Katrineholm, Sweden, examines how the ink key preset may be done using low- resolution digital images stored in the vendor independent data format CIP3 PPF. The press that has been used has a control interface that is not accessible from the outside. This feature is shared with a lot of older presses. Therefore several methods of how to present and collect ink key settings using offline methods have been tested. </p><p>To investigate the relationship between mean coverage over one ink zone and its corresponding ink key opening data from a 32-page web offset press has been collected. The mean coverage was taken from the CIP3 PPF files that were related to the collected print jobs. </p><p>The relationship that was found between the coverage and the opening can be described with a transfer curve (one curve per printing unit and side). Using as few as three print jobs of high quality (density and dot gain within given tolerances) a first set of transfer curves may be created. These are close to the real ones and using print jobs where the ink key presettings have been calculated the transfer curves may be calibrated to perform better and better presetting calculations. To generate and calibrate the transfer curves and to extract the mean coverage values from the CIP3 PPF files and recalculate these to presetting values a computer program called IKPS (Ink Key Presetting System) was made. IKPS was made using MATLAB from MathWorks INC. </p><p>IKPS have been tested for ink key presetting during a number of print jobs. Even though the transfer curves were uncalibrated the system performed well. As comparison the results from a plate scanner was used. Even if online transfer of the presetting values is preferable the big advantage with the IKPS is that it is an offline system and therefore it is possible to implement it on any kind of offset press, old as well as new. In order to generate reliable transfer curves the print jobs used for calibration must be of high printing quality and representative for that particular press. How the ink key presettings are presented in the press control room depends on what kind of press it is. IKPS works with CIP3 PPF files as well as low-resolution cmyk tiff files.</p>

The present work related to apply hot-melt ink-jet process for imaging at offset lithographic printing form, to utilise a reusable surface for many times and particularly related to validating thermal and ultrasonic erasing processes. This dissertation investigated systematically the role of certain factors towards affecting erasing image area process on print surfaces. Thermal erasing process approved to melt and suck the image area from the surface, the results were adopted by using contact angle measurements and scanning electron microscope. Ultrasonic erasing process permitted to solve the image area by choosing erasing chemistries, influence of selected erasing chemistries on printing surface, and evaluation the process, the results were tested by UV/Vis spectrometer, contact angle, profileometery and visual microscope<br>Der Fortschritt im Bereich von Charakterisierung und Verständnis für Hot-melt Ink Jet Prozesse zur Bebilderung von Offsetdruckform-Zylindern ist ein Ergebnis dieser Forschung. Die Systematik dieser Arbeit basiert auf einem theoretischen Teil, um einen geeigneten Löschprozess auszuwählen. Der Löschprozess hängt von den Eigenschaften des Hot-melt Ink Jet Materials und der genutzten Aluminiumdruckoberfläche ab. Diese werden systematisch im Labormaßstab experimentell untersucht. Der thermische Prozess wurde einerseits durch Benetzbarkeitsprüfungen und anderseites durch Rasterelektronmikroskopaufnahmen bewertet.Der Ultraschallprozess ist ein nasser Löschprozess. Die Untersuchungen wurden in vier Stufen systematisch durchgeführt - Auswahl vom geeigneten Lösungsmitteln - Einflüsse von ausgewählten Lösungsmitteln auf nicht beschichtete und beschichtete Aluminium platten - Evaluation eines Ultraschalllöschprozesses - Validation eines Löschprozesses; zur Bewertung des Löschprozesses wurden mehrere Druckplattenproben bebildert und gelöscht Die Ergebnisse wurden durch UV/Vis Spektrometer, Kontaktwinkel, Profiliometrie und Visuelle Mikroskopie getestet

The aim of this work was to develop a solid knowledge on formulation effects controlling offset ink-paper coating adhesion and to identify key factors of the coating and printing process affecting it. Focus lay on comprehending the impact of pigment dispersant on ink-paper coating adhesion and ultimately on the print quality of offset prints. The work covers laboratory studies, a pilot coating trial designed to produce coated material with a span in surface chemistry and structure, and an industrial offset printing trial. The lab scale studies quantified ink-paper coating adhesion failure during ink setting with a developed laboratory procedure based on the Ink-Surface Interaction Tester (ISIT) and image analysis. Additional polyacrylate dispersant resulted in slower ink setting and reduced ink-paper coating adhesion, with a dependence on its state of salt neutralisation and cation exchange, mainly in the presence of moisture/liquid water. The industrial printing trial on pilot coated papers was designed to study how these laboratory findings affected full scale offset print quality. These trials confirmed the dispersant-sensitive effect on ink-paper coating adhesion, especially at high water feeds. Evaluation of prints from the printing trial resulted in two fundamentally different types of ink adhesion failure being identified. The first type being traditional ink refusal, and the second type being a novel mechanism referred to as ink-lift-off adhesion failure. Ink-lift-off adhesion failure occurs when ink is initially deposited on the paper but then lifted off in a subsequent print unit. In this work, ink adhesion failure by this ink-lift-off mechanism was observed to occur more often than failure due to ink refusal. Print quality evaluation of the industrial prints suggested that water induced mottle was caused by a combination of ink-surface adhesion failure, creating white spots on the print, together with variation in ink layer thickness due to emulsified ink.<br><p>QC 20161019</p>

碩士<br>國立交通大學<br>光電科技學程<br>104<br>Currently there is a world wide effort to develop solar generated electrical power . In our country , the renewable energy law is at the legislation stage . The research and development as well as the capability of domestic equipment mechanical manufacturing plants for solar cell printing process are quite mature . In general , the qualities of equipment manufactured domestically are not inferior to that of imported equipment . The main weakness is in the system integration of the by domestically made automated tools. This area still requires dedicated effort of mechanical manufacturing companion. There for it is essential to equipment the screen printing , offset printing , and inkjet printing technology for solar cell application. The results of our analyse of screen printing , inkjet printing and offset printing of silicon solar cell printing process are as follow： 1.From the angle of production yield , all three printing technology can reach the reguired yield. 2.To reach a line width 40μm or less in the printing of conduction line only inkjet printing and offset printing can reach the goal . 3.In terms of production throughput , the order is offset printing , screen printing and inkjet printing . Production cost is closely related to production throughput. 4.In the material consumption of conductive parte , from the highest consumption the order is screen printing , offset printing and inkjet printing. 5.Offset printing has high product yield , lower product cost , and the capability to print line are close to 20～35μm . Its high production speed can reach 22.01m/s , it is the most suitable printing technology for current future linewidth requirement . To consider product throughput , and production cost , only offset printing surely to for all to meet the goal . For the increased demand of solar cells in the near future . it is essential to consider offset printing are an option when there is need of the expansion of the production line . It is advised to upgrade the current screen printing tools by considering the more offset printing technology .

This experimental study compares green printing technologies (ink and stock) to traditional printing technologies (ink and stock) regarding how they compare in quality. The quality was measured using the print characteristics of gray balance and dot gain. A comparison of the two independent variables (ink and stock) was conducted to determine if a difference exists for the selected characteristics. It has been suggested that the green technologies, despite being more environmentally friendly, are not as high in quality and therefore result in a lower quality printed piece. This research used a four-color test form that was printed using both the green and traditional technologies. The characteristics were measured using an X-rite 528 spectrodensitometer, after which the data were analyzed and conclusions reported. The results of the study suggest that there is no practical significance between the different inks and stocks employed in this study. It was determined however that the best print quality in terms of dot gain (meaning the least amount of dot gain) resulted from the combination of green technologies (ink and paper).<br>Department of Technology

Tese de mestrado em Química Tecnológica, Universidade de Lisboa, Faculdade de Ciências, 2021<br>A tradição da resinagem em Portugal é longeva, estando inicialmente a sua atividade fortemente ligada ao equipamento naval em madeira. Da resina extraída do pinheiro vivo separa-se, através da destilação, a terbentina e a colofónia. Enquanto a terbentina encontra a sua aplicação como solvente orgânico e diluente de tintas e vernizes, a colofónia é utilizada como material de partida na produção de resinas com destino à produção de tintas de impressão ou outras coberturas de superfícies embora o seu uso sem recurso a modificações conheça também muitos outros domínios. Modificada, a colofónia pode sê-la de forma simples ou complexa. Transformações simples da colofónia, como a obtenção do seu aducto com anidrido maleico ou ácido fumárico, ou a produção de esteres simples, que visam principalmente a melhoria das suas propriedades intrínsecas. Também através das modificações já mencionadas, a colofónia pode ser utilizada como unidade estrutural principal para a produção de poliésteres de peso molecular elevado. A performance física e química destas resinas confere às tintas produzidas propriedades que permitem alcançar rotinas de impressão de qualidade. Em particular, as tintas para impressão offset requerem um comportamento altamente viscoso por se destinarem a processos de alta-rodagem, sendo o seu aspeto muitas vezes semelhante a pastas. Esta propriedade, entre outras de igual relevo, é conferida pela resina com a qual a tinta é produzida. Assim, a própria resina necessita de apresentar características adequadas a esta aplicação, sendo elas, principalmente, a viscosidade e a solubilidade em verniz. A colofónia é então modificada através da formação de adutos e esterificação, mas ainda com recurso à introdução de Resol, resina de fenol e formaldeído, para que possa satisfazer os critérios de solubilidade e viscosidade em verniz. Contudo, a utilização de fenóis e formaldeído acarreta atenção redobrada aquando do processo de produção que os envolve, assim como no tratamento de resíduos associados. Existe ainda uma preocupação crescente relacionada com as suas origens, nomeadamente no caso do fenol, que provem de matérias de natureza fóssil. Assim, desenvolver um produto de performance semelhante às resinas modificadas com fenol-formaldeído é não só uma antecipação sensata de futuras necessidades, como um ato de responsabilidade ambiental. Este trabalho, desenvolvido e suportado no Grupo Respol, visa precisamente a investigação e desenvolvimento de uma resina com origem na colofónia, que possua um comportamento semelhante às suas equivalentes produzidas com recurso a fenol e formaldeído. Por ser um trabalho sustentado na ideia de antecipação de um futuro panorama e por estar fortemente ligado à indústria, a informação de acesso publico relacionada diretamente com esta temática é reduzida. Em adição, nenhum produtor à data da realização deste trabalho oferece, na sua gama de produtos, resinas de colofónia sem fenol e formaldeído com desempenho semelhante aos objetivos propostos. Numa consulta aos dossiers de produto registados no âmbito do REACH, realizada no final de 2020, não constam resinas derivadas de colofónia produzidas com recurso a novas matérias-primas ou processos. Pode constatar-se que para além da não comercialização, também não se prevê que tal venha a acontecer num futuro próximo, uma vez que o registo deve anteceder a entrada de um produto no mercado. Com acesso unicamente às técnicas, química e formulações já conhecidas desta indústria, foram delimitadas as guias principais deste trabalho e desenhado um plano de abordagem ao problema. Assim, este trabalho possui um carácter fortemente marcado pela ausência de suporte de trabalhos anteriores que possam indicar de forma mais clara um método a seguir e por isso possui uma natureza bastante relacionada com a procura e averiguação da abordagem mais viável, permitindo depois uma investigação aprofundada e mais ciente dos contornos do problema. O presente trabalho teve início com a caracterização de algumas amostras industriais de resina de colofónia produzida com recurso a fenol e formaldeído. Compreender o comportamento do Resol na resina e como este afeta a viscosidade e solubilidade, de modo a poder desenhar uma solução mais meditada para o problema em mãos foi considerado o objetivo principal. Desde estudo, conclui-se que o Resol para além de criar pontes lineares longas, com peso molecular considerável, entre moléculas de ácidos resínicos, fá-lo ainda através de uma estrutura de natureza altamente solúvel em óleo alifáticos, mais ainda que a própria colofónia. Em adição, a natureza da sua ligação química é estável e a mobilidade de cadeia contribui para aumentar a viscosidade. Um poliéster de colofónia é tipicamente produzido com recurso a monómeros de pequenas dimensões, como os ácidos resinicos, adutos de colofónia e polióis como o pentaeritritol. A porção fenólica é a única com extensão apreciável e por isso é a entidade que permite criar algum distanciamento entre centros mais condensados compostos pelos restantes monómeros. Com a remoção do Resol, este espaço que permite à macromolécula respirar perde-se e obtém-se uma estrutura fortemente intrincada que resulta na perda de viscosidade e na redução da superfície de contacto com o solvente. Reintroduzir estruturas deste tipo na matriz da resina pode então permitir recuperar total ou parcialmente o comportamento perdido com a remoção do Resol. É importante então que estas estruturas sejam principalmente lineares, ou com backbone linear, sejam maioritariamente alifáticas ou com exterior alifático, que possam ou tenham origem em recursos renováveis e sejam de toxicidade reduzida ou nula. Alguns polímeros pensados para responder a estas necessidades foram sintetizados e introduzidos mais tarde na produção da resina de colofónia. Alguns dos monómeros utilizados nestes pré-polímeros foram ainda introduzidos como tal em formulações de resina de modo a tentar obter algum tipo de estrutura linear in situ e sem recurso a preparações adicionais. Além da possível reintrodução de estruturas deste tipo ponderou-se e testou-se a utilização de algumas modificações simples na formulação da resina que incluem alterações de processo, introdução de polióis altamente funcionais e modificação com óleos vegetais de cadeia curta, entre outros. É ainda importante referir que existe uma relação muito forte entre as propriedades da viscosidade e solubilidade em resinas sem Resol. Modificações que aumentam a solubilidade implicam sempre perdas de viscosidade e vice-versa, sendo por isso ainda mais importante encontrar métodos que permitam escapar a esta dualidade. Das modificações simples mencionadas, a adição de componentes em duas fases produziu aumento significativo da viscosidade sem perca de solubilidade, quando comparada com a mesma formulação com adição numa fase e solubilidade média. Ficou evidente que a modificação ao processo permite alterar apenas umas das propriedades, neste caso a viscosidade. No entanto, quando se tentou recorrer a este método para aumentar a viscosidade de uma formulação de solubilidade alta, não se verificou o seu incremento. É possível que este efeito apenas se confirme a partir de um dado limite inferior de componente éster, que regula fortemente o fator da solubilidade. Outras modificações como a utilização de outros óleos vegetais e polióis de alta funcionalidade não produziram efeitos apreciáveis. Da utilização de poliésteres substitutos de Resol, ou seus monómeros, na formulação de resinas verificou-se que para valores de solubilidade próximos dos desejados, a resposta viscosa é depreciável. No entanto, em ambos os casos confirmaram-se a existências de espécies de baixo peso molecular em quantidades muito superiores às típicas de resinas produzidas com recurso a fenol e formaldeído. A presença destas espécies é responsável pelo aumento da polidispersividade de pesos moleculares e consequente redução da resposta viscosa. Contudo, como no caso destas formulações se introduziram novas espécies químicas é plausível que o limite inferior de Mw para obtenção de resposta viscosa possa ser simplesmente superior aos que se encontram habitualmente em resinas fenólicas.<br>As a natural resin, rosin has been used as an ink component for the properties it imparts the resulting ink. Modifications to natural rosin have been long studied and later applied in ink making to yield better performing products. One major modification is the incorporation of Resol, phenol-formaldehyde resin, with rosin. Modifying rosin in such fashion allows it to display improved solubility in vegetal and mineral drying oils, another major component in inks. Nevertheless, there are several health and environmental hazards associated with formaldehyde and alkyl phenols used in Resol production, thus it is important to search alternative solubility inducing modifications to rosin resins permitting the drop of Resol. Samples from the production of Resol modified rosin resins were investigated to better understand the behavior of Resol. Later, comparable structures to that of Resol were theorized and produced either as pre-polymers later added in resin making reactions or integrating the resin making process itself. Although results answering directly to the goals of this work were not achieved, the not so satisfactory outcomes do serve a purpose. They may guide the correct path for future research in this field and raise questions which were not thought of before. Briefly, ester linkage should be reduced or concealed. Bulkier structures are preferred as they raise softening point. Aliphatic groups are needed to raise solubility. Higher molecular weights might be required. Other polymers besides polyester may also be utilized but raise questions about bio decomposition. The evaluation systems of these new resins could be modernized as they will possibly serve new functions.

The present work related to apply hot-melt ink-jet process for imaging at offset lithographic printing form, to utilise a reusable surface for many times and particularly related to validating thermal and ultrasonic erasing processes. This dissertation investigated systematically the role of certain factors towards affecting erasing image area process on print surfaces. Thermal erasing process approved to melt and suck the image area from the surface, the results were adopted by using contact angle measurements and scanning electron microscope. Ultrasonic erasing process permitted to solve the image area by choosing erasing chemistries, influence of selected erasing chemistries on printing surface, and evaluation the process, the results were tested by UV/Vis spectrometer, contact angle, profileometery and visual microscope.<br>Der Fortschritt im Bereich von Charakterisierung und Verständnis für Hot-melt Ink Jet Prozesse zur Bebilderung von Offsetdruckform-Zylindern ist ein Ergebnis dieser Forschung. Die Systematik dieser Arbeit basiert auf einem theoretischen Teil, um einen geeigneten Löschprozess auszuwählen. Der Löschprozess hängt von den Eigenschaften des Hot-melt Ink Jet Materials und der genutzten Aluminiumdruckoberfläche ab. Diese werden systematisch im Labormaßstab experimentell untersucht. Der thermische Prozess wurde einerseits durch Benetzbarkeitsprüfungen und anderseites durch Rasterelektronmikroskopaufnahmen bewertet.Der Ultraschallprozess ist ein nasser Löschprozess. Die Untersuchungen wurden in vier Stufen systematisch durchgeführt - Auswahl vom geeigneten Lösungsmitteln - Einflüsse von ausgewählten Lösungsmitteln auf nicht beschichtete und beschichtete Aluminium platten - Evaluation eines Ultraschalllöschprozesses - Validation eines Löschprozesses; zur Bewertung des Löschprozesses wurden mehrere Druckplattenproben bebildert und gelöscht Die Ergebnisse wurden durch UV/Vis Spektrometer, Kontaktwinkel, Profiliometrie und Visuelle Mikroskopie getestet.