Kâğıdın yüzey pürüzlülüğünün, baskı renk değişimi, ışık haslığı ve baskı parlaklığına etkisi

Mürekkebin baskı yüzeyini ıslatması, yayılması ve yerleşmesi farklı şekillerde olmaktadır. Kâğıt yüzeyi ne kadar kaba ve ne kadar makro gözenekli bir yapıya sahipse, basılı mürekkep o derece fazla yayılır ve kâğıt içine nüfuz eder. Basılmış mürekkebin kâğıt yüzeyine yerleşme ve penetre olma sürecinde kâğıdın yüzey topoğrafisi son derece belirleyicidir. Kâğıdın yüzey özellikleri basılabilirlik açısından, basılı bir ürünün optik kalitesini etkileyen başlıca niteliklerdir . Bu çalışmada, kâğıdın yüzey yapısının baskıda renk sapması, baskı yoğunluğu ve baskı parlaklığı gibi basılabilirlik parametrelerine etkisi tespit edilmeye çalışılmıştır. Bu amaçla farklı yüzey kabalığına sahip kaplanmamış kâğıt yüzeylerine standart baskı şartlarında DIN ISO 2846-1 standartlarına uygun mineral yağ bazlı tabaka cyan renk ofset mürekkebi ile test baskıları yapılmıştır. Baskı odası şartlarında serbest kurumaya bırakılan test baskılarının zemin ton yoğunluğu ve parlaklık ölçümleri tam kuruma gerçekleşene kadar periyodik olarak tekrarlanmış ve kayıt altına alınmıştır. Çalışmada özellikle kâğıt yüzeyi pürüzlülüğünün mürekkep renk değişikliği-ışık haslığı ve baskı parlaklığına etkileri deneysel olarak incelenmiş ve sonuçları basılabilirlik ve baskı kalitesi açısından tartışılmıştır

AN EXPERIMENTAL RESEARCH ON HYSTERETIC BEHAVIOR OF RC BEAMS UNDER SIGNIFICANT GRAVITY LOADS

In this study, hysteretic behavior of RC beams with and without significant gravity load effects are investigated. To this purpose, an experimental program is carried out in which gravity loads are applied by force controlled test procedure whereas cyclic loads are applied by displacement controlled test procedure. The results of tests with gravity load effect are compared with the results of control specimens with increasing displacement loading profile. Experimentally observed damage states and deformation demands are compared with the respective values proposed by Turkish Seismic Design Code. It is found that, the loading procedure with significant gravity load effect leads to the formation of unidirectional plastic hinges. Besides, the deformation capacities of the specimens are found to be much higher than the code based deformation capacities

Effects of flotation deinking on the removal of main colors of oil-based inks from uncoated and coated office papers

This paper presents the results of trials to evaluate the color-stripping behaviour of offset printing colors and the effect of coating on deinking performance. Oil-based four-color inks were separately printed as base printing on coated and uncoated white poster paper, and then extensive pulping and deinking processes were carried out. Standard offset printings were conducted on paper samples using cyan, magenta, yellow, and black colors (CMYK), and the effects of deinking efficiency on the removal of each color were analysed. The pulps were made at Micro-Maelstrom Laboratory Pulper at specified conditions with and without bleaching agents. Formamidin sulfinic acid and hydrogen peroxide formulation were used as reductive and oxidative bleaching agents, respectively. Flotation deinking and thickening of pulp were practiced using Degussa flotation and thickening cell. The changes in the optical properties, such as brightness, whiteness, and color value (CIE L?, a? b?) of deinked pulp were determined. It was found that optical properties of color-stripped pulps from coated papers were better than that of uncoated office papers. However, yield was quite low in coated papers since fillers were lost during flotation process. Cyan color was found to be the most difficult one in four main color printing inks stripping out in deinking process

The effect of green biobased binder on structural, mechanical, liquid absorption and wetting properties of coated papers

Synthetic styrene-butadiene (SB) and styrene-acrylic (SA) latex binders used in paper coating formulations are common and based on unsustainable petroleum sources. Today\u27s papermaking industry turns towards sustainable substitutes that do not compromise quality, and reduce carbon emission, toxic substance release and waste disposal concerns related to fossil fuel sources. In this study, colloidal starch-based latex nanoparticles that do not require cooking were used for pigment coating and coated on the paper surfaces. The effects of these new biobased binders on the structural and mechanical strength properties, liquid absorption, wetting and surface topography of the paper were investigated and compared with the properties of coated paper that SB latex was used as a coating binder. The results demonstrated that the biobased latex decreases the grammage of paper while maintaining an identical thickness relative to the SB latex samples. The porosity, permeability and roughness of biobased latex are found higher than the SB latex. The biobased latex successfully replaced SB latex at 1:1 ratio and enabled an equivalent of bursting, tear, tensile strength and structural properties

Controlling unequal surface energy results caused by test liquids: the case of UV/O3 Treated PET

Ultraviolet/ozone (UV/O3) treatment has been reported to be an effective method to modify properties such as wettability, adhesion or adsorption of plastic surfaces. The change in the surface is measured by contact angle analysis, which employs liquids and their surface tensions (ST) to estimate the surface energy (SE). We found two different practices in the scientific community: (1) the majority of researchers adopted the ST value of liquids from the literature, while (2) other researchers conducted real-time measurements in the lab under ambient conditions prior to SE estimation. To the best of our knowledge, there is no study that compares the difference between the two practices. One study was found to show different SE methods generating unequal SE values for the same substrate. However, there was no definitive conclusion backed by general thermodynamics rules. In this study, we presented (1) a statistical significance test that showed the literature and experimental ST values are significantly different, and studied (2) the effect of different liquid pairs on the SE estimation for UV/O3 treated poly(ethylene terephthalate) (PET) substrate. Modification techniques such as atmospheric pressure plasma or chemical modification were studied previously to examine PET’s wettability and the SE. The UV/O3 treatment was studied to improve adhesion and to modify its chemical properties for adsorption. In contrast, we studied (3) the effect of UV/O3 on wettability at different timeframes and addressed (4) how to control unequal SE based on a method that was refined on a rigorous thermodynamic three-phase system. It must be noted that this method can be generalized to other types of solid surfaces to estimate thermodynamically self-consistent SE values. This work also provides (5) a web-based calculator that complements computational findings available to the readership in the data availability section

Use of nanoparticle binders for paper coatings: A review

Starch is a biopolymer that is used as a co-binder alongside synthetic petroleum based latex binders for paper coating applications, though it causes production downtimes due to the problems during cooking process, such as gelling; lack of full expansion of starch granules; increase in viscosity during cooling; bacteria growth in cooked starch and difficulties in viscosity control during storage. On the other hand, synthetic binders negatively affect paper recyclability and biodegradability. To overcome these problems, a new biopolymer binder has been introduced to the paper manufacturing, being used initially as a partial replacement for petroleum based synthetic latex polymers. This study reviews the recent developments of nanoparticle biopolymer binders, referred to as biolatex binders. These binders are shipped dry and can be dispersed in water without cooking requirement while improving paper quality and reducing costs of paper manufacturing. They also provide quality benefits, coater runnability improvements and new higher solids coating formulations for future product advancements

Kâğıt geri dönüşümünde enzim ve ultrasonik enerji kullanımı

Medeniyetin kurulmasında, bilgi depolama ve aktarımında tartısmasız bir yeri olan kâğıt, günümüzde artık çok çesitli amaçlar için hayatın her kademesinde yer almakta, giderek tüketimi inanılmaz boyutlara ulasmaktadır. Kâğıt sektöründe hammadde problemine çözüm için, sürdürülebilir ormancılık çalısmalarından daha ziyade, sürdürülebilir geri dönüsüm teknolojilerini gelistirmek gerekmektedir. Bu anlamda atık sınıfına giren kâğıtın, lifler dısında bulunan bütün bilesenlerini en ekonomik ve çevreci metotlarla ayırmak son derece önemlidir. Bu çalısmada, toner baskılı ofis kâğıtlarının mürekkep ve kirliliklerinden arındırılmasında enzim ve ultrasonik enerji kullanımı konusunda elde edilen bazı sonuçlar tartısılmıs ve geri dönüsüm açısından kâğıt sektörü çevresel açıdan irdelenmistir.Paper has undeniable key roles in establishing civilization, archiving and transferring knowledge. Paper is in all parts of daily life for different purposes today and its consumption is getting at unbelievable level. For solving the problems related to insufficient raw materials, the sustainable recycling technologies should be developed rather than concentrating on sustainable forestry practices. In this sense, extracting all materials from waste papers with economical and environmentally friendly methods are extremely important. In this study, some results obtained from an experimental study carried out on the deinking of toner printed office papers with the help of enzymes and ultrasonic energy were discussed and paper industry was examined in respect to recycling and environment

Surface analysis of polymer films for wettability and ink adhesion

The interaction between inks and substrates is critical during printing. Adhesion of the ink film is determined by the reciprocal interactions of polar and nonpolar (dispersive) components between polymer films and inks. The greater the similarity between the polar and dispersive components of inks, coating and substrates, the better the wetting and adhesion on the surface of printing substrate. Various liquid materials in printing such as inks, varnishes, lacquers, and adhesives contain high ratios of water. The highly polar nature of water makes the interaction of these materials unsuitable with predominantly disperse polymer surfaces. Some films with polyolefin structure, especially polypropylene, and polyethylene, are nonpolar and cannot form strong bonds with ink, varnish, or lacquer coatings due to their chemical structure. Increasing surface energy components overcomes the poor wetting and adhesion on polymer surfaces. In this review, the topics of water contact angle measurement and determination of surface energy, surface tension, and using sessile drop method for the wettability and ink adhesion of polymer films are surveyed. Information on structural and chemical processes was given that assists in obtaining wettable film surfaces. Recommendations were made for good adhesion and printability based on surface treatment methods and ink modification