(1) Appearance Quality and Common Defects of Pieces of Paper For lithographic paper, a piece of paper with good appearance quality should meet the following conditions:
1) The paper in each individual sheet is very neatly laid out, with no jagged or misaligned conditions.
2) Each additional sheet of paper must be separated by a small clear seal or each packaged separately in wrapping paper.
3) Each sheet of paper is lined with a moisture-proof paper and a cardboard sheet on the bottom and top respectively, and then packaged in three layers of wrapping paper or two layers of cement paper.
4) Clipboard should be completely solid, flat and dry, so as not to damp or crush the paper.
5) There are no common damages such as deformation, loose parts or cracks, whitening, etc. To check the appearance quality of a piece of flat paper, it is generally necessary to first look at all the pieces of paper that arrive in the same batch, to see if there are any paper pieces that are deformed, loose or damaged, and to record the number and degree of damage. Then you can tear the outer packaging of several pieces of paper side to see if each additional paper is placed neatly, and there is no interval mark between the other and the quality of the package. If necessary, you can also unpack one or two of the packages to see if there is any moisture or scratches.
â–²After transporting, loading and unloading of lithographic paper into the use department, the following quality problems often occur:
1) It is the thin and unstiffened cardboard. After transport and handling, some paperboards are broken and the paper is damaged. Some paperboards are deformed due to lack of strength, and the resulting flat paper is shaped like a drum, causing the paper to be deformed. Difficult to use.
2) It is the number of outer paper layers is not enough or the strength is too poor, after the loading and unloading, transportation, the outer package is generally broken, so that the paper inside is exposed to the wind and sun, and even rain is contaminated.
3) It is the paper sheet itself that is not in alignment. After a long period of tying, the misplaced paper edge presses the mark. This kind of paper is not easy to be edging before printing, and it is prone to glitches or lack of size. It is also sometimes found that a piece of paper in an individual piece of paper protrudes a lot and is folded and squeezed to make it scrap.
4) The humidity of the clipboard is too high, and the paper absorbs moisture from the clipboard and then deforms. As a result, a large stack of paper near the clipboard cannot be used normally.
5) It is the height and inclination of the paper itself. Each piece of paper is one side high and one low. This type of paper is easy to dump during palletizing, and there is a certain difficulty in continuous printing during printing.
★ Appearance Quality and Common Defects of a Rolled Web The appearance quality of a rolled web refers to the appearance quality of the roll. The finished product of the web is a web wound by a reel-winder with a longitudinal slitter having a predetermined width, and rolled with a certain tension into a roll of paper having a suitable tightness and diameter. The web is composed of core, paper roll, and outer packaging. Therefore, the appearance quality of the rolled paper is mainly determined by whether the paper roll has defects, whether the end surface is good, and whether the outer packaging and the core are in good condition and how many joints there are. It is decided without damage.
Since the quantification and thickness of the paper tend to be somewhat uneven in the transverse direction (width direction), after rewinding the roll with such a paper, although the appearance may not show any abnormality, it is When pressed hard or beaten with sticks, it will be noticed that the hardness of the web is not uniform enough, loose on one side or tight on the other. When hitting with a stick, the sound of the tightly rolled part is crisp and loud, and the part of the roll that is rolled looses. When the web is being taken up, the pressure on the tight side and the loose side of the web is not the same. Therefore, when the web is used for printing, it is difficult to make the whole web subjected to uniform force, and tilting occurs during the printing process. Such phenomena as folding and twisting of snakes, as well as the formation of print wrinkles and misregistration, ghosting and other failures, can also deviate from the midline at the beginning of the machine folding. When such a paper is rewinded, the greater the tension, the more severe the resulting distorting phenomenon. It is also possible to bias the paper web so that one end of the two ends of the reel is depressed and the other middle is convex and flared. However, when the roll paper tension is too small and the roll is too loose, it is easily deformed or even crushed during transportation or coding.
The web presents a "ditch" like a washboard and a "beam" on the surface of the roll. This defect is called "beads" and "meihuagou". It is mainly due to the uneven weight or moisture of the paper sheet. All caused. The protruding defects that can be seen on the end face of the web are the so-called "star-shaped end faces" ("prignon-shaped end faces"). Such a web is mainly due to the fact that the tension at the initial stage of rewinding is too small and the tension after rewinding is too great.
Sometimes you can see the end of an individual web, with a rectangular mark, usually deep to light from the outer edge of the end face. Such paper often breaks and breaks when it is used. This is due to the fact that several rolls of paper are taken up at the same time when they are close together. In addition, it is inevitable that the cut paper web will fluctuate. This will cause the slitted paper edges to sometimes “bite†together, resulting in simultaneous roll-over. Several reels that were taken had undercuts, and they could not be opened after rewinding. They had to be hit with a heavy hammer at the junction of two paper rolls in order to spread the two paper rolls. This leaves a "scar" on both ports of the reel.
The problem of web joints is also very important, and joint bonding has a direct impact on web printing performance. If the joint is poorly adhered, it will result in misprints due to incorrect seams in the printing process, and it is also prone to breaks.
In addition, when inspecting the appearance quality of web printing paper, it is necessary not only to check whether there is deformation of the cylinder core, paper tube deformation, but also to see if the core is strong, there are no wood stoppers at both ends of the core, and the core There is no damage at the end.
The final aspect of the appearance quality of rolled webs is the outer packaging and the presence or absence of breakage.