Screws Bolts Studs,Washer Series,Nut Series,Rivet Series YRX Technology (Shenzhen) Co., Ltd. , https://www.yrx-tech.com
Judging the quality of printing paper from five aspects
BAIDU_CLB_fillSlot("858283");
The quality of paper is judged mainly from the following aspects
(1) Appearance quality. Appearance quality refers to defects that can be observed by the naked eye such as dust, holes, pinholes, clear spots, wrinkles, pleats, streaks, screen prints, felt marks, spots, pulp, cloud flowers, cracks, and inconsistent color.
(2) Basic physical properties. The basic physical properties include the most common properties of paper such as basis weight, thickness, tightness, smoothness, hardness, softness, compressibility, and absorbency.
(3) Mechanical properties. Mechanical properties, also known as mechanical properties or strength properties, are divided into static strength and dynamic strength.
1 Static strength is the maximum force that paper can withstand under slow stress, also known as final strength. It includes the following quality indicators: tensile strength, bursting resistance, tearing, folding resistance, stiffness and so on.
2 Dynamic strength refers to the strength of paper that can withstand transient impact, which reflects the dynamics of instantaneous diffusion of paper after stress. The dynamic strength mainly includes the following indicators: puncture strength, ring pressure strength, compressive strength, etc., which are the most important quality indicators for packaging paper and paperboard.
(4) Optical properties. Optical properties refer to whiteness (brightness), color, gloss, transparency, opacity, and the like. For printed paper, the optical properties of the paper are very important, which directly affects the quality of the printed matter.
(5) Chemical properties. The chemical properties of the paper include the chemical composition of the paper, the hygroscopicity of the paper, ash, sizing, acidity, and durability.
It should be specially pointed out that if the water content of the paper is uneven, it will cause the paper to be deformed. How to eliminate the malfunction caused by the paper?
Since the water content of the paper is not uniform, "flank", "tight side" and "curl" deformation and the like are liable to occur.
The relative humidity of the printing workshop is relatively high. When the original water content of the paper is too low, the edge of the paper will absorb water and elongate. If the middle part is too late to absorb moisture, the paper will lose its original flatness, and the paper edge will be “wavyâ€, commonly known as “ Ruffled edge."
The relative humidity of the printing workshop is low. When the original water content of the paper is high, the edge of the paper is dehydrated faster, and the four sides of the paper are upturned to produce a "tight edge".
The water content of the paper is too small, the fibers shrink in both the horizontal and vertical directions, and the water content on both sides of the paper is different, and the paper curls toward the relatively dry side.
The deformation of the paper mainly affects the normal paper conveyance, the overprinting accuracy, and the wrinkles caused during the printing process. To eliminate the deformation of the paper due to uneven water content, the main method is to scientifically adjust the paper to balance the water content of the paper, and also to knock the paper to reduce the deformation of the paper.