Talking about the influence of paper silk on printing and postpress

Paper is the most important printing material in printing production. The quality of paper directly determines the quality of printing and the post-press processing. Paper properties include surface properties, structural properties, optical properties, chemical properties, etc. Any of these properties can affect the quality of prints. The paper analyzes the effects of the paper structure on the printing and post-press processing. Paper is mainly composed of thin fibers that are intertwined with plant fibers. The length, strength, alignment, and degree of bonding of the fibers affect the quality of the paper. The orientation of the fibers is the problem of silk defects in the paper.

1. The formation of silk defects

In the pulp, the arrangement of the plant fibers after beating is disorganized, but when papermaking on a high-speed papermaking machine, the fibers will be aligned along the direction of movement of the copper mesh of the paper machine due to the effect of gravity and inertia. Like the water in the water is arranged in the same direction. Although due to the vibration effect of the paper machine, a small amount of fiber arrangement is still disorderly and the directionality of the fiber arrangement is weakened, the fiber in the paper still exhibits a significant longitudinal and lateral difference. .

2. The effect of paper silk on printing

The influence of silk on the printing has always been underestimated by people. It is believed that the influence of silk on the printing is not significant, and there is no effect such as the surface strength, smoothness, gloss, and whiteness of the paper on the printing quality. . Is the effect really small? Of course not, its influence on printing can be analyzed from the following aspects.

1) The effect of paper deformation on overprint

We know that the main components of fiber are cellulose, hemicellulose and lignin, while cellulose is a high molecular compound made up of multiple glucose monomers (-C6H10O5-), while hemicellulose is made up of pentose and hexose. The glycan molecules, which contain multiple hydroxyl groups in their molecular structure, are very polar and easily absorb water, which is one of the reasons why paper is prone to absorb water. Both fiber diameter and length direction will absorb water, but the deformation is not the same, the diameter of the diameter of the expansion deformation is almost 2 to 8 times the length of the deformation; while the dehydration will also produce shrinkage, shrinkage deformation is also the diameter of the length ratio The direction is much larger, which can cause different deformations in the length and width of the paper. This distortion will affect the quality of the image transferred to the paper, and in particular, misprints will occur.

In addition, the deformation of the paper when subjected to pressure and tensile forces is also related to the orientation of the fibers, with small longitudinal deformation and large lateral deformation. Therefore, in order to solve this problem, it is necessary to look for the direction of the paper when printing paper, otherwise it will cause great quality problems. So how do you judge the direction of the paper? General paper packaging will be clearly marked on the mark, you can also determine this, generally the long side of the paper and the fiber length direction is called longitudinal fiber paper, and the long side of the paper is perpendicular to the fiber length direction is called horizontal silk paper. At the same time, the method of tearing the paper can also be used. After tearing the paper, the direction in which the slit is relatively straight is longitudinal, and the slit is sawtooth or relatively oblique in the transverse direction. The warp thread paper should be used during printing. Because the fiber diameter direction is consistent with the printing direction, the deformation of the paper can be compensated by the increase or decrease of the cylinder liner to compensate for the misregistration of the image, and axial deformation is difficult. make up.

2) Other influences

In addition to the large impact on the deformation of the paper, which affects the printing quality, it also affects the tensile strength, bending strength, and tear strength.

1 tensile strength. It is the ability of the paper to resist elongation and produce elongation. The size of the paper depends on the strength of the fibers in the paper and the strength of the bond. From the silk properties of paper, we can see that the paper has good tensile strength in the longitudinal direction, because the longitudinal direction is the direction of the fiber length, and its strength is better; while the lateral direction depends on the binding force between the fiber molecules only, the tensile strength is poor. Therefore, the longitudinal direction of the web should be the longitudinal direction of the paper, otherwise it will easily cause the phenomenon of web break and affect the printing efficiency and print quality.

2 folding degree. It is the ability of the paper to withstand repeated folding under a certain tension. The degree of folding resistance is mainly affected by the strength, length and binding force between the fibers. Because the longitudinal direction of the paper is the fiber length direction, it has the ability to resist folding better, while the lateral direction only depends on the molecular binding force of the fiber, and the ability to resist folding is poor. Therefore, for certain printed products that are repeatedly folded, such as banknote paper, various security papers, map papers, books, exercise books, etc., the use of paper with good folding-resistance should be selected, especially in the direction in which the number of folds is large. Silk problem. Otherwise it will break easily after a certain period of time.

In addition, there is a certain requirement for the paper stringers during the folding and binding process. When multiple folds are to be made in a certain direction, the folding endurance in this direction should be better, so as to avoid the folding knife being folded. Causes the paper to break. However, when the book is bound, in order to make the book look better when opened, the book can be well fixed. At this time, the direction of the paper is preferably the direction of the fiber and the orientation of the spine.

3 Tear. The size of the paper resists tearing. By the same token, the degree of paper tear depends on the strength of the fiber and the strength of the bond. Longitudinal direction of the longitudinal paper, that is, the long side direction of the paper due to the joint effect of fiber binding force and fiber strength, has better tear resistance, is not easy to tear, the jagged surface of the tear surface will appear uneven, and longitudinal paper In the longitudinal direction, ie, in the direction of the short side, only the fiber binding force is easily tearable, and the tearing surface is relatively neat. Therefore, the paper should pay attention to the degree of tearing when printing paper and folding. At the same time when binding also pay attention to which direction is easy to cause damage, then the tear resistance in this direction should be better.

In short, the problem of silk defects in paper is still a problem that cannot be ignored in the process of printing, post-press processing and packaging. Now that the papermaking process cannot effectively avoid the problem of silk defects, we must adopt various methods to pay attention to the direction of the paper in printing, post-printing, and packaging, so that the printing quality and service life can be guaranteed.

Basic Info

Model NO.: GY
Title: Cosmetic Packaging Tube
Thickness: 0.2mm-0.5mm
Surface Handling: Offset, Hot Stamping, Silk Screen, Labeling
Tube Color: White, Black Transparent, Colored
Coating: Glossy, Matte
Capacity: 3-500ml
Cap: Flip Top Cap, Screw on Cap
Shape: Round/Oval/ Flat/Heteromorphic
Trademark: GF
Transport Package: PVC Bag Individual Master Carton
Specification: 30g-250g
Origin: Jiangsu, China (Mainland), Yangzhou
HS Code: 39173100

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