The appearance of graphical paper is determined by its brightness and color which is adjusted by optical brightening agents (OBAs) and dyes. This addition of OBAs and dyes is commonly controlled and monitored according to the scanner values of the pope roller. This common practice has many flaws including the delay between dosage of the additives and the actual measurement, the danger of overdosage when a change in furnish occurs as well as the fact that during a sheet break there is no value which the dosage can be related to as the last measured value does not reflect the reality of the process. In the scope of a diploma thesis it could be demonstrated how, with help of the inline sensor BT-5400 UV, OBA and dye can be measured and controlled. In a practical example the sensor was installed after the deculator of a fine paper machine. The OBA and two dyes were dosed directly into the pulp suspension as well as a further OBA dosage in the size press. The time between dosage, inline measurement and pope measurement amounts to less than 10 minutes. This allows for a control loop with fast reaction. The real-time measurement of OBA and color allows a reduction of broke production, faster grade changes, avoidance of over- or underdosing and close control during web breaks where scanner values are not available. The installation of the inline sensor BT-5400 UV in combination with a control loop enables a fast amortization of the investment and an increase in productivity and paper quality.
Przedstawiona praca wykazała, że liczba miejscowych zagłębień w papierze (kraterków) o wymiarach powyżej określonych wartości granicznych jest bardzo mocno skorelowana z liczbą "brakujących punktów" rastrowych (missing dots) powstających w drukowaniu wklęsłym i w związku z tym struktura powierzchni papieru z pewnością wywiera największy wpływ na drukowność papieru tą metodą. Średnia głębokość tych kraterków wynosi 2-5 μm, a ich średnica mieści się w zakresie 50-250 μm. Kraterki powodujące występowanie "brakujących punktów" w drukowaniu wklęsłym z elektrostatycznym wspomaganiem druku ESA muszą być z reguły większe. Jednak ukształtowanie struktury powierzchni papieru nie opisuje i nie wyjaśnia w pełni przyczyn występowania "brakujących punktów" podczas drukowania. Również czynniki niezwiązane z topografią powierzchni, takie jak właściwości elektryczne (zwłaszcza w przypadku stosowania elektrostatycznego wspomagania druku ESA), rozkład włókien i pigmentów, przyjmowanie farby czy mikrościśliwość, mogą wywierać wpływ na drukowność w aspekcie "brakujących punktów". Na występowanie "brakujących punktów" w istotny sposób wpływają także czynniki niezależne od papieru, np. farba drukowa i maszyna drukarska.
EN
This work has shown that the number of local defects (craters) beyond certain limit values correlates very well with the number of missing dots, and therefore the surface topography of the paper has definitely the greatest impact on printability in rotograwre. The deepenings have an average depth of 2-5 μm and diameters between 50-250 μm. When ESA is used bigger craters as regards depth and diameter are necessary to cause missing dots. However, not all missing dots can be explained and described by means of surface topography. Non-topographic factors, such as elec-tric properties of papers (especially when using the ESA), fibre and filler distribution, ink absorbency or micriscopic compressilility can also have an influence on printability as regards missing dots. Paper independent factors (e.g. printing ink orprinting machine) may also have a certain influence on missing dots. Therefore, investigations in these fields, together with the results of topography analysis, are necessary in order to draw clear and general conclusions regarding the causes of missing dots in rotogravure printing.
Digital information, fiberoptics, and telecommunications satellites are making it possible to implement the concept of the global village. The sector is responding to this opportunity in virtual laboratories, virtual product development teams, and virtual factories where individuals and facilities which are remotely located are linked for the common good as well as the task at hand even allowing a continual effort to be on a project as the work day moves around the globe. Eventually this situation will also be recognised by the academic community and knowledge will be transferred between libraries, and students instantly between locations on the globe. Through the Internet such possibilities are now being initiated. However, it will be the long term commitment of the private sector to the concepts of telecommuting, remote distance and digital libraries which will ensure its The termination of the Cold War has conditions allowing the implementation of concepts. Economic conditions currently within the United States are quite robust to an acute shortage of qualified experts. In and Central Europe employment levels are not as high while in the Republics of the Former Union large numbers of trained experts are employment. Consideration may also be to other areas of the globe such as the Pacific Rim, Africa, and South America. Through the of computer/telecommunication in regions lacking local infrastructure it is to link individual talent with scientific, engineering, and technical needs worldwide as well as to provide the opportunity for the acquisition of marketable and desired skills and training. In Summer 1999 prototype Viewnet centers will be established in St. Petersburg, Moscow. Yerevan, Kiev, and Dnepropetrovsk which will be linked through evolving lntemet2 systems to participating locations within the United States allowing the rapid transfer of very large files as well as the transmission of the highest quality audio and video. Such multinational connectivity should in the future provide considerable political and economic stability for the world.
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