Dissertations / Theses on the topic 'Paper Printing properties Testing'

The Printing Industry is undergoing a Digital Revolution . The importance of digital printing has been increasing substantially over the last decade. How has this development affected the paper selection of printing firms? Only paper suppliers who successfully anticipate the changing needs of the printing firms will be able to benefit from the industry trend. This paper employs a probability model to analyze a survey data set of 103 digital printing firms in the USA and Canada. The research idea is to link the firm s paper selection with the firm s characteristics in order to gain insights into the printing firm s paper purchase behavior and the overall industry structure. The first part of this work investigates the importance of certain paper aspects, such as price, runnability and print quality. Strikingly, a company s involvement in digital printing, measured by the percent of digital printers of the total number of printers in the firm, is a central determinant of the importance of all paper aspects analyzed. This finding underscores the tremendous importance of the printing firms transition to digital printing for the Paper Industry. Paper runnability is found to become more important the faster the firm grows and can be explained by the fact that more successful firms incur higher opportunity costs from downtime. Another key finding is that the importance of paper price is lower for firms who collaborate with their customer on the paper selection and are able to pass on cost increases in the paper price. The second part involves a more direct assessment of paper selection. Here, the firm s characteristics are utilized to explain the choice of coated versus uncoated paper for the printing job. The analysis shows that firms involved in sophisticated print services, such as Digital Asset Management or Variable Data Printing are more likely to use the high quality coated paper. Further it is found that the usage of coated paper increases with catalog printing whereas it decreases with book and manual printing.

Os novos processos de impressão têm exigido novas características do papel. Entre os novos processos encontram-se as impressões digitais, em especial, a impressão por jato de tinta. Este tipo de impressão é baseado na ejeção de uma gota de tinta por um orifício em uma cabeça de impressão, que atinge o substrato formando um pixel. A definição das imagens formadas neste tipo de impressão é, portanto, dependente das características da tinta e, principalmente, do substrato. O presente trabalho tem por objetivo caracterizar as propriedades do papel que são importantes para a impressão por jato de tinta, desde o momento em que a tinta atinge a superfície do papel até a sua absorção. As propriedades consideradas neste estudo foram: a rugosidade, a porosidade e as propriedades químicas da superfície. A rugosidade foi avaliada pelos métodos tradicionais da área de papel e celulose (baseados em vazão de ar), por método perfilométrico e, qualitativamente, por imagens obtidas por microscopia eletrônica de varredura (MEV). Para a porosidade foi utilizado um método tradicional, além de porosimetria de intrusão de mercúrio e microtomografia de raios X, e a composição química da superfície foi avaliada por espectroscopia por energia dispersiva (EDS) e espectroscopia Raman. A partir dos resultados obtidos, as propriedades do papel foram qualificadas e as suas influências no espalhamento e absorção de líquidos em geral foram identificadas. Além da caracterização das propriedades superficiais e porosimétricas do papel, as correlações entre as propriedades e os diferentes métodos utilizados na sua determinação foram discutidas. Os métodos de análise tradicional não conseguem caracterizar os papéis em níveis de resolução capazes de fornecer informações sobre a influência das propriedades estudadas na impressão por jato de tinta. Ao mesmo tempo, a caracterização do papel para este tipo de impressão e a compreensão das influências das propriedades do papel no espalhamento e absorção de tinta e líquidos em geral só é possível quando as propriedades são analisadas em conjunto.
The new printing processes have required new features of the paper. Among the new printing processes are the digital printing, in particular, the inkjet printing. This type of printing is based on the ejection of an ink drop through a hole in a print head, which reaches the substrate forming a pixel. The resolution of the images formed in this type of printing is therefore dependent on the characteristics of the ink, and especially of the substrate. The present work aims to characterize the properties of paper that are important to the inkjet printing, from the moment the ink hits the paper surface to its absorption. The properties considered in this study were: roughness, porosity and chemical properties of the surface. The roughness was evaluated by traditional methods in pulp and paper sector (based on air flow), by profilometry and qualitative using images obtained by scanning electron microscopy (SEM). For the porosity, a traditional method was used, and also mercury intrusion porosimetry and X-ray microtomography. The chemical composition of the surface was evaluated by energy dispersive spectroscopy (EDS) and Raman spectroscopy. From the results obtained, the paper properties were described and their influence on the spreading and absorption of liquids in general have been identified. Besides the characterization of the paper surface properties and porosity, the correlations between the properties and the different methods used for measurement were discussed. The traditional analysis methods can not characterize the paper in levels of resolution capable of providing information about the influence of the properties studied in inkjet printing. At the same time, to characterize paper for this printing process and to understand the influences of the paper properties on the spreading and absorption of inks and liquids in general the paper properties have to be analyzed together.

Thesis (MA)--Stellenbosch University, 2003.
ENGLISH ABSTRACT: The aim of this study was to investigate the psychometric properties of a screening test of cognitive ability, the Paper and Pencil Games Level 2 (PPG Level 2), for Tigrignaspeaking schoolchildren in Eritrea. This study represents one of the first attempts to measure cognitive ability in Eritrea. The PPG was developed in South Africa (Claassen, 1996) as a group test of general cognitive ability for children in Grade 2 and 3 (PPG Level 2), and Grade 4 and 5 (PPG Level 3). The PPG provides Total, Verbal and Nonverbal ability scores. The Verbal Scale consists of two subtests, namely (a) Verbal and Quantitative Reasoning and (b) Comprehension. The Non-verbal Scale consists of three subtests, namely (a) Figure Classification, (b) Figure Series, and (c) Pattern Completion. Although the PPG has the appearance of a standardized intelligence test, Claassen emphasized that it is best used as a screen for academic difficulties or failures. Participants were 577 Tigrigria-speaking Grade 3 children. The children were selected from schools in the capital, Asmara, from small towns, and villages. Eleven schools participated. The participants can be considered representative of the Grade 3 Tigrignaspeaking population in Eritrea. The PPG Level 2 was completed under supervision of the researcher. Classical and Rasch item analyses were conducted on the Verbal and Non-verbal Scales, respectively. The internal consistency of the Non-verbal scale can be considered satisfactory for a screening instrument (Cronbach's a = .85). Furthermore, the non-verbal items showed satisfactory fit to the Rasch model (INFIT values and OUTFIT values < 1.3 for all items), suggesting that they measure a unidimensional construct. In addition, the item difficulty estimates corresponded well with the serial order of the items, with easy items being presented earlier than more difficult items. The internal consistency of the Verbal scale was lower (Cronbach's a = .72), which can probably be attributed to the relative easiness of the items for the particular group of participants. The verbal items also showed satisfactory fit to the Rasch model. The Rasch analysis, which expresses person ability and item difficulty on the same scale, clearly showed that the Verbal items were too easy for the majority of the children. However, it should be kept in mind that the PPG is intended to discriminate among children with low ability. Hence, the observed mismatch between the abilities and item difficulties was not unexpected. It should also be noted that the serial order of the items did not correspond well with item difficulty, with some difficult items being presented early and some easy items presented late in the scale. The five subtests of the PPG were subjected to a confirmatory factor analysis. Two models were specified and compared. Model 1 specified a single general factor; this provided a more parsimonious description of the data and showed a satisfactory fit with the data, though a bit weaker than that of Model 2. Model 2 specified two correlated factors, namely a Verbal and a Non-verbal factor. Model 2 also fitted the data well, but a high correlation between the factors was observed (r = .77; r2 = .59), suggesting the presence of a general factor. The results provide support for two levels of interpretation, namely on the Total score level and the Verbal and Non-verbal level. The validity of the PPG Level 2 was further investigated by examining the correlations between the PPG scores and teacher ratings of academic achievement. Because different schools had different raters, the correlations within each of the schools were pooled to obtain an estimate of the correlations between the PPG scales and academic achievement for the total group. The pooled correlation for the PPG Total score with academic achievement was .56, for the Non-Verbal score .53, and for the Verbal score .41. The correlations for the Total and Non-verbal scores are similar to those typically reported in the educational psychology literature and provide support for the validity of these scales as a screen for academic difficulties. The results show that the PPG, which was developed in South Africa, may be fruitfully exported to Eritrea. It is recommended, however, that before the PPG Level 2 is routinely used for screening purposes with Tigrigna-speaking children, the functioning of the Verbal Scale should be re-examined and possibly some of the Verbal items should be rewritten.
AFRIKAANSE OPSOMMING: Die doel van die onderhawige studie was om die psigometriese eienskappe van 'n siftingstoets van kognitiewe vermoë, naamlik die Paper and Pencil Games Level 2 (PPG Level 2), vir Tigrigna-sprekende kinders in Ertirea te bestudeer. Hierdie studie verteenwoordig een van die eerste pogings om kognitiewe vermoë in Eritrea te meet. Die PPG is in Suid-Afrika ontwikkel (Claassen, 1996) as 'n groeptoets van kognitiewe vermoë vir kinders in Grade 2 en 3 (PPG Level 2), en Grade 4 en 5 (PPG Level 3). Die PPG lewer tellings van kognitiewe vermoë op drie vlakke, naamlik Totaal, Verbaal en Nie-Verbaal. Die Verbale skaal bestaan uit twee subskale: (a) Verbale en Kwantitatiewe redenering en (b) Begrip. Die Nie-Verbale skaal bestaan uit drie subskale, naamlik (a) Figuur Klassifisering, (b) Figuurreekse en (c) Patroonvoltooiing. Alhoewel die PPG op die oog af soos 'n konvensionele intelligensietoets lyk, beklemtoon Claassen dat dit te beste geskik is as 'n siftingsinstrument vir akademiese probleme of mislukkings. Die deelnemers was 577 Tigrigna-sprekende kinders in Graad 3. Die kinders is uit skole van die hoofstad, Asmara, klein dorpe en geselekteer. Elf skole het aan die studie deelgeneem. Daar kan aanvaar word dat die deelnemers verteenwoordigend is van die Graad 3 Tigrigna-sprekende populasie in Eritrea. Die PPG Level 2 is onder supervisie van die navorser voltooi. Klassieke en Rasch item-ontledings is op die Verbale en Nie- Verbale skale, onderskeidelik, uitgevoer. Die interne konsekwentheid van die Nie- Verbale skaal kan as bevredigend vir 'n siftingsinstrument beskou word (Cronbach se a = .85). Hierbenewens het die Nie-Verbale items 'n bevredigende passing met die Rasch model getoon (INFIT gemiddelde kwadrate en OUTFIT gemiddelde kwadrate < 1.3 vir alle items), wat daarop dui dat die items 'n essensiëel eendimensionele konstruk meet. Die moeilikheidswaardes van die Nie- Verbale items het ook sterk ooreengestem met die volgorde waarin die items in die skaal aangebied word - die maklike items is eerste aangebied en daarna die moeilike items. Die interne konsekwentheid van die Verbale skaal was laer (Cronbach se a = .72). Die laer koëffisiënt kan waarskynlik aan die relatiewe lae moeilikheidsgraad van die Verbale items toegeskryf word. Die Verbale items het egter ook 'n bevredigende passing met die Rasch model getoon. Die Rasch ontleding, wat vermoë en item moeilikheid op dieselfde skaal uitdruk, het duidelik getoon dat die Verbale items te maklik vir die meeste kinders was. Daar dien egter op gelet te word dat die PPG ontwerp is om te diskrimineer tussen kinders met relatiewe lae vermoëns. In hierdie lig gesien is die swak passing tussen vermoë en item moeilikhede nie te onverwags nie. Die volgorde waarin die items in die skaal aangebied word het ook nie goed ooreengestem met die item moeilikheidswaardes nie - sommige moeilike items is vroeg in die skaal aangebied en sommige maklike items laat in die skaal. Die vyf subtoetse van die PPG is aan 'n bevestigende faktorontleding onderwerp. Twee modelle is gespesifiseer en vergelyk. Model 1 het 'n enkele algemene faktor gespesifisieer.

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).
Department of Technology

The effects of coating formulation on thermal characteristics of coating layers were systematically studied for xerographic toner fusion on coated papers. Model coatings were formulated using three types of ground calcium carbonate and one kaolin pigments, each mixed with 6, 10, 18, and 25 pph of styrene butadiene latex binder. Porosity was found to be a key parameter for coating thermal conductivity adjustment, and was determined by the latex concentration. The particle size distribution and morphology of pigments also affect the overall thermal characteristics of coating layers. Print qualities on model coated papers were evaluated by print gloss measurement, toner adhesion test, and pair-wise visual ranking, and it was proved that print gloss is reduced with increasing bulk thermal conductivity of coating layers. The coating layer consisted of Covercarb HP pigment and 10 pph of latex was found to have the best performance in the three print quality evaluation tests.

Indiana University-Purdue University Indianapolis (IUPUI)
Fused deposition modeling (FDM) represents one of the most common techniques for rapid proto-typing in additive manufacturing (AM). This work applies image based thermography to monitor the FDM process in-situ. The nozzle temperature, print speed and print orientation were adjusted during the fabrication process of each specimen. Experimental and numerical analysis were performed on the fabricated specimens. The combination of the layer wise temperature profile plot and temporal plot provide insights for specimens fabricated in x, y and z-axis orientation. For the x-axis orientation build possessing 35 layers, Specimens B16 and B7 printed with nozzle temperature of 225 C and 235 C respectively, and at printing speed of 60 mm/s and 100 mm/s respectively with the former possessing the highest modulus, yield strength, and ultimate tensile strength. For the y-axis orientation build possessing 59 layers, Specimens B23, B14 and B8 printed with nozzle temperature of 215 C, 225 C and 235 C respectively, and at printing speed of 80 mm/s, 80 mm/s and 60 mm/s respectively with the former possessing the highest modulus and yield strength, while the latter the highest ultimate tensile strength. For the z-axis orientation build possessing 1256 layers, Specimens B6, B24 and B9 printed with nozzle temperature of 235 C, 235 C and 235 ➦C respectively, and at printing speed of 80 mm/s, 80 mm/s and 60 mm/s respectively with the former possessing the highest modulus and ultimate tensile strength, while B24 had the highest yield strength and B9 the lowest modulus, yield strength and ultimate tensile strength. The results show that the prints oriented in the y-axis orientation perform relatively better than prints in the x-axis and z-axis orientation.

Dissertação de Mestrado Integrado em Engenharia Química apresentada à Faculdade de Ciências e Tecnologia da Universidade de Coimbra
Ao longo dos últimos anos, as exigências em torno dos produtos provenientes da indústria do papel têm vindo a aumentar de forma exponencial. Os papéis de impressão e escrita, apesar dos avanços tecnológicos, nunca deixaram de ser largamente utilizados como suporte de dados e imagem tanto ao nível doméstico como empresarial. A necessidade de encontrar fatores de diferenciação que cativem os clientes leva a uma constante procura por alternativas. O objetivo deste trabalho é o de aplicar diferentes formulações celulósicas na superfície de papéis de impressão e escrita sem qualquer tratamento prévio, com vista a avaliar o seu potencial para a melhoria das propriedades de impressão, bem como propriedades mecânicas e óticas. Neste trabalho foram aplicadas formulações previamente estudadas e preparadas, contendo principalmente nano e microfibrilas de celulose e amido. A aplicação de nanofibrilas de celulose foram o foco deste trabalho, sendo utilizadas duas formulações que diferem apenas no grau de oxidação na sua produção. Foram efetuados ensaios de caracterização aos papéis revestidos como: ensaios de resistência mecânica, penetração de água, propriedades óticas e de qualidade de impressão. Nos ensaios de resistência mecânica não foi possível tirar conclusões devido à elevada quantidade de água presente nas formulações de nanofibrilas de celulose (cerca de 99 % (w/w)). A resistência ao ar, também avaliada, como seria de esperar aumenta com uma maior quantidade de formulação aplicada devido ao consequente maior empacotamento na superfície do papel. Nas propriedades óticas não se obtiveram resultados muito diferentes derivados dos revestimentos. Os ensaios de penetração revelaram hidrofílicidade da nanocelulose, a qual conferiu uma maior velocidade de absorção de água. Os resultados considerados mais positivos para a qualidade de impressão foram obtidos para as nanofibrilas mais oxidadas, aplicadas sob a forma de dupla camada. Considerando como referência o papel base sem qualquer revestimento, foram calculados o fator delta (Δ) da área Gamut e densidade ótica relativa, tendo-se obtido um Δ área Gamut = 1092 e a densidade ótica relativa de 1.12.
Over the last years, the requirements regarding products from the paper industry have been increasing exponentially. Printing paper, despite the technological advancements, has never stopped being widely used as data and image support, at both the domestic and business level. The need to find differentiation factors that captivate clients leads to an incessant search for alternatives. The purpose of this work is to apply different cellulosic formulations on the surface of printing paper without any previous treatment, in order to evaluate its potential for improvement of the printing properties, as well as mechanical and optical properties. In this work, the formulations applied were previously studied and prepared, containing mainly cellulose nano and microfibrils and starch. The application of cellulose nanofibrils was the focus of this work, using two formulations which differ only in the degree of oxidation in their production. Several characterization tests to the coated papers were carried out, such as: mechanical resistance tests, water penetration, optical properties and print quality properties. Regarding the mechanical resistance tests, it was not possible to draw any conclusion due to the high amount of water present in the cellulose nanofibrils formulations (around 99 % (w/w)). The air resistance, also assessed, increases with a higher amount of formulation applied, as expected, due to the consequent higher packing at the paper surface. The results obtained for the optical properties of the coated paper were not much different. The water penetration tests revealed the hydrophilic character of the nanocellulose, which granted it a greater rate of water absorption. The results considered most positive for the print quality were obtained for the most oxidized nanofibrils, in the form of a double layer. Considering as reference the basic paper without any coating, the delta (Δ) Gamut area factor and relative optical density values were calculated, obtaining: Δ Gamut area = 1092 and relative optical density of 1.12.