In the actual production process, the direction of the paper thread has an important influence on the overprinting during printing and the appearance effect after binding into a booklet. To a large extent, it affects both the internal quality of the book and the appearance of the book. 1. Paper thread direction Paper is an interwoven fabric of fibers. Traditionally, we call the direction of the majority of fibers aligned with the direction of papermaking straight lines; the direction perpendicular to it is called the direction of horizontal threads of paper. Paper fiber is a hydrophilic substance, which absorbs water to swell and releases water to shrink. The penetration and disappearance of moisture between the fibers causes relative displacement between the fibers, and its length and width change. This is the stretchability of the paper. According to the experiment, the diameter of a dry fiber can increase by 30% after being completely wetted, but it can only increase by 1% to 2% in the length direction. Therefore, the stretch rate of the paper in the direction of straight threads and the direction of horizontal threads is different. Generally speaking, the expansion and contraction ratio of the transverse direction of the paper is 2 to 8 times that of the straight direction. 2. Identification of the direction of the silk lock Due to the significant differences in the physical properties such as the stretch rate and stiffness of the paper in the straight thread direction and the horizontal thread direction, there are many ways to distinguish the paper thread direction. Here are a few simple and easy methods. 1. Folding method: Fold each time in two directions of the paper, and the direction where the crease is smooth and straight is the direction of the straight thread. Third, the offset printing process on the consideration of paper thread Offset printing uses the principle of water-ink balance to make pictures appear on paper. The contact between paper and fountain solution will cause the paper to stretch. As mentioned earlier, the degree of stretchability of the paper is related to the direction in which the fibers are arranged. The stretch rate in the direction of straight strands is less than that of transverse strands. Therefore, the offset printing process is customary to use the paper straight thread direction parallel to the cylinder axis to print, in order to minimize the inaccurate graphic overprint caused by the paper's hygroscopic elongation. This is particularly important in multi-color printing. There is also a view that, from the perspective of paper feeding, the straight thread direction of the paper is relatively stiff, which is convenient for blowing and conveying; while the stiffness of the paper in the horizontal thread direction is not enough, the two ends are easy to curl downward or upward, which affects the blow loose and conveying. Therefore, the paper should be printed parallel to the direction of the straight strands of the paper and the direction of the paper feed. This view certainly has some truth, but it is a bit of "scrapping the book". Because our ultimate goal is to produce high-quality printed products, in this regard, it is far more important to seize the main contradictions to avoid overprinting than to facilitate paper feeding. In addition, if the same batch of purchased paper cannot be used when printing a book, or if the small offset press uses a small cutting residue, in these cases, it must be ensured that the same book printed in the same batch cannot be mixed with different yarns. The direction of the paper. Otherwise, it will not only result in inaccurate overprinting due to the different paper expansion and contraction, but even the edge of the finished product will be uneven after a period of inventory. Fourth, the binding process of paper thread direction considerations The direction of the paper thread in the binding process is particularly important for the ring liner. The ring liner is an indispensable part of the hardcover book. The cover is firmly adhered to the book block by glue, which can protect the book block and increase the appearance. Due to the different stretch rates of different fiber directions in the paper, the direction of the loop-lined horizontal thread lock and the stitching are easy to produce wrinkles, and the straight line thread direction is consistent with the stitching and the appearance is smooth. Wrinkles are likely to occur when the direction of the ring liner and the stitch are the same. This is because: when the ring liner is pasted by the glue solution, the moisture in the glue solution wets the ring liner to make it elongate, and the elongation in the direction of the transverse thread is larger. With the gradual loss of moisture during the drying process, the direction of the horizontal strands shrinks, and the ring has been fixed by the glue at the stapling position. In this way, the paper generates an internal stress, and the concentration of the internal stress facilitates the formation of wrinkles. Conversely, when the direction of the straight wire strands is consistent with the stitching, the expansion and contraction of the horizontal wire strands is limited by the glue fixation, and the sticking place is flat. Therefore, the ring liner must make the direction of the straight thread parallel to the stitching when opening the material. If the ring backing is not blank, the arrangement direction should also be considered during imposition. Upvc Doors offer a low maintenance solution, they also keep your home warm and by keeping noise and draughts out your guaranteed a more relaxing homely atmosphere, all pvc doors offer unrivalled security with hinges and locks that are fitted directly to the door`s steel reinforcement. Upvc Doors,Upvc Patio Doors,Upvc Exterior Doors,Upvc Double Doors Lingyin Construction Materials LTD , https://www.lingyincn.com
2. Suspended law enforcement: Cut paper strips of the same length along the vertical and horizontal sides of the paper, hold one end with your fingers, and the direction of the small degree of bending is the direction of straight strands.
3. Wetting method: After placing the paper on the water for a period of time, observe its curling direction. The direction of the curling axis of the paper is the straight thread direction.
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