Determination of maximum uniformity and paper qual

2022-08-17
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Uniformity measurement and paper quality

people will agree that uniformity is an important factor in determining paper quality. However, the relationship between evenness and the determination of paper quality is very complex, and of course, other variable factors are also involved

 it may be too simplistic to assume that the visual uniformity of the setting is only the quality of the paper, and there is a one-to-one dependency between them. However, it is difficult to say how much effect the uniformity has on the performance of the paper. Theoretically, in addition to the uniformity sensor, it is also worthwhile to install the sensor on the paper machine. According to different varieties, to determine the quantity, thickness, surface roughness, optical properties, moisture, ash, elasticity and moisture content

58853. Although a general evenness index (1) has been proposed. The evenness is generally related to the micro gram weight change of paper and paperboard, such as within the range of 0.1 mm and 100 mm. This may also be related to minor changes in other properties of the paper, such as related properties, porosity, thermal properties, surface roughness, surface energy, and so on. Even if we have a satisfactory instrument to measure the uniformity, such as micro gram weight, there are many kinds of determination methods. In these methods, such data (2, 3 and 4) may be used to show the determination results. The situation may be more complicated when we consider the distribution of other papermaking raw materials, such as fillers, sizing agents and coatings

 constantly emphasize the paper quality, and pay more attention to the forming part and humidity of the paper machine. As mentioned above, uniformity is related to Quantitative Micro changes, so we can't consider what independent factors have changed in the macro. In the latest information, Parker and Moore mentioned a new web monitoring method, which can effectively provide five orders of magnitude of forming variation data, such as from 1 to 1 × 105 mm. It is interesting to see how changes in a length order affect other problems. Quantitative large, medium and small changes may be important to the processing performance and final use performance of paper and paperboard. However, the specific impact of them remains to be further studied

"good evenness can improve the quality of paper. Although there is a lack of intuitive data, the efforts to improve evenness have been continuous. Generally, we believe that when the headbox concentration increases, the uniformity decreases. In addition, improving the directionality of fiber arrangement, especially for the old headbox, also has a negative impact on the uniformity. However, the newly developed double shaper and upper shaper can not only improve the directionality of paper, but also put forward the original opinion of Jean Claude Steinmetz, chairman of the China Europe automotive materials Commission (apimc), that is, the design type of headbox and the disturbance of pulp flow affect the variable rate of paper quantity to varying degrees

 uniformity measurement methods include optical technology, such as laser and video C14 β Radiography β P147, X-ray and electron beam technology of light source. Almost all commercial off-board and on-board uniformity testers use transmitted light, reflected light under certain conditions, and various scanning methods. Evenness is also an important factor for the performance of paperboard, especially for panel paper. It is hoped that the paperboard can meet the printing requirements. However, as recently stated by Zang and Aspler, we need to continue to investigate the factors of uniformity. The high quantification and opacity of the natural color vermicelli board limit our ability to measure the uniformity. In addition, generally speaking, the vermicelli board is not a single-layer structure. Therefore, the relatively important surface and bottom evenness and its measurement need to be studied. The compression strength of the carton from the surface layer to the bottom layer is another important performance, which depends on the internal compression ratio of the components of the cladding layer and the middle layer of the impact testing machine. We found that when the uniformity decreased, the variation rate of short spacing compression strength increased significantly

"the influence of evenness on paper properties, especially in machine measurement, is briefly discussed, and the working procedures supported by the measurement technical committee of the American forestry and paper society and financially assisted are commented. At the same time, the exciting development work to improve the wet end function of the paper machine is improved

. When measuring toilet paper, paper, offset paper and paper bag paper, it is found that the results of linear scanning measurement and regional scanning measurement are basically the same, and the uniformity measurement instrument can be used to measure the visual uniformity, but there are considerable reasonable differences in the obtained data

 we hope to know what other sensors and uniformity testers will be used to measure the uniformity in the future. The strength property and adaptability depend on the uniformity

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