Quality of printing paper and paper disease
We are a big printing company in Shenzhen China . We offer all book publications, hardcover book printing, papercover book printing, hardcover notebook, sprial book printing, saddle stiching book printing, booklet printing,packaging box, calendars, all kinds of PVC, product brochures, notes, Children's book, stickers, all kinds of special paper color printing products, game cardand so on.
For more information please visit
http://www.joyful-printing.com. ENG only
http://www.joyful-printing.net
http://www.joyful-printing.org
email: info@joyful-printing.net
Common paper disease
Paper defects that are not included in the paper quality technical requirements can be referred to as paper sickness. Paper sickness includes not only invisible, but also certain performance defects that can be known through experimentation or printing, such as brittleness, offset, lint, powder drop, etc., including those that can be directly seen or felt. Various defects and defects on the surface of the paper, such as dust and dirt. The latter is referred to herein as the appearance of paper.
The appearance of paper is very sick, including dust, spots, net marks, felt marks, "cloud flowers", seersucker, wrinkles, creases, dirty spots, turf, transparent spots, warm spots, holes, embossing, scars, pulp, Hard blocks, uneven weight, poor uniformity, etc. These appearances are caused by paper, some are brought in by the paper before papermaking, some are caused by poor technical operation or poor technology in the papermaking process, and others are caused by poor environmental hygiene in the factory. Once it appears, it is relatively continuous, such as felt marks and "cloud flowers", once it appears, if it does not take measures, it always exists; some appearance paper diseases have some chance or a long time interval, such as dirty spots , holes and so on. Some paper diseases will make the quality of the paper worse, such as dust, felt marks, etc.; some paper diseases make the paper a waste, such as offset paper with hard blocks or copper plate with large dirty spots. Paper can only be disposed of as waste.
According to different types of common paper diseases can be divided into:
Paper volatility fluctuations and unevenness of paper size
The first type of fluctuation is generally caused by periodic vibration of the flow system of the paper material to the headbox, vibration caused by the shaking of the front rotor blade of the headbox or the vibration of the slurry pump, and sometimes due to the uniformity of the headbox. The pulp roller is bent or the opening is unreasonable. The second type of fluctuation is generally caused by unreasonable production processes or improper operation management.
Poor formation
1) Agglomerated structure: refers to a state in which fibers are entangled with each other to form a mass.
2) "Cloud Flower": Also known as cloud-like tissue, it means that the fibers in the paper are distributed like clouds on the paper.
3) Dislocation of fibrous tissue: refers to poor fiber interlacing in the running direction of the paper machine.
4) Wavy fibrous structure: refers to a wavy thickened layer of curved curvature along the width of the paper.
5) Pulp sub-segment: refers to some longitudinal strip-like lint marks visible on the paper web.
Dust, spots, sand and hard blocks
1) Dust: It can be divided into three types: "dust-like dust", "non-metallic dust", and "metal dust".
2) Spot: can be divided into "wet spot and steam spot", "cylinder spot", "calender spot", "slurry spot", "bubble spot", "filler spot and paint spot", "bright spot and white spot" ".
3) Sand: refers to the presence of sediment, lime residue, carbon residue and other hard mineral sand on the paper surface.
4) Hard block: refers to the blocky material or coarse-grained material that is hard on the paper and is higher than the paper surface, such as wood knots, grass joints, pulp blocks, etc., which is the most harmful to printing.
Holes and curtains
1) Hole: refers to the hole that is completely penetrated on the paper and has no fibers. Holes can be divided into pinholes, holes and holes by size.
2) Through the curtain: refers to the fact that the fiber layer on the paper sheet is thin but not completely penetrated, and its light transmittance is larger than other parts of the paper sheet. These small ideas are called light transmission points, and the larger ones are called transparent curtains.
Embossing and various imprints
1) Embossing: refers to the collapse of the fibrous tissue forming the wet paper under the excessive pressure during the pressing process, leaving the paper surface with scattered distribution, irregular shape, high transparency and many gaps. The small pinhole, the phenomenon that this wet paper is crushed by the press roll is called embossing. Severe embossing tends to cause the wet paper to break at the press section.
2) Streak: refers to the strip marks that are different from the gloss or color of the paper under the illumination of light.
3) Feather cloth marks: refers to the marks on the paper of the latitude and longitude lines of the papermaking felt.
4) Other imprints: net marks, watermark roll marks and vacuum roll marks.
Fold and curl
1) Folding: refers to the folding or overlapping of paper sheets to form a crease or crease. Can be divided into two types of dead and live.
2) Warping and arching: Warping refers to the state in which the two sides or four corners of the paper are lifted and the middle is concave; the arching refers to a state in which a large area of the middle or middle portion of the paper is arched, and the two sides or the four corners are recessed.
3) Bubbling and bubble sand: Bubbling refers to partial shrinkage of the paper sheet, resulting in a convex bubble on the paper surface, and fine wrinkles on the paper surface around the bubble; bubble sand means that the paper surface is arranged A denser bubble point.
4) Various wrinkles: divided into wrinkles, fine wrinkles, curl wrinkles, etc. according to size and shape.
Other paper diseases
1) Crack: Refers to a crack or break in the middle or edge of the sheet.
2) The paper edge is not neat and unclean: the paper edge is not neat. On the one hand, the paper edge cannot be parallel or rectangular after the paper is cut, or the paper edge has burrs, bends and twists. On the other hand, the paper is cut and selected. After the paper code is placed unevenly or rewinded, the end face has a phenomenon of "outward and outward". Unclean paper edge means that the paper has burrs, zigzag edges, missing edges and dirty edges after cutting.
3) Inconsistent hue: It means that the whiteness and color of the same batch of products are inconsistent with the paper.
4) "Lotus lace": refers to the edge of the paper, especially the longitudinal edge, which loses its proper straight state, and is in a curved state that is not in the same plane as the paper surface.
5) Obvious two-sided difference: You can see the obvious difference between the two sides of the paper with a naked eye (except for single-sided offset paper and single-sided coated paper).
6) Incomplete, broken and shredded paper: Incomplete and broken sheets refer to paper with incomplete sheets, with missing corners, missing edges, broken or only half a piece; shredded paper refers to the size of the paper. A small piece of paper.
The appearance quality of the paper means that the quality of the recognized paper can be discriminated by the human sense only without using the equipment. It can be divided into the appearance quality of the paper itself and the appearance quality of the paper formed from a sheet of paper or a long strip of paper.
Regardless of the quality of the appearance, the use of paper is affected to varying degrees. Poor appearance quality will not only reduce the use value of paper and the yield of printing, but also make paper waste. In addition, some serious paper defects such as hard paper pieces in the paper may also damage the printing plate and the rubber roller during printing, causing damage to the printing equipment. The appearance quality and physical properties of paper are also closely related. For example, papers with obvious seersucker appearance, such as smoothness and opacity, will also be affected.
The appearance quality inspection of paper should achieve the following three purposes:
Check the quality of the paper.
Holes and curtains
1) Hole: refers to the hole that is completely penetrated on the paper and has no fibers. Holes can be divided into pinholes, holes and holes by size.
2) Through the curtain: refers to the fact that the fiber layer on the paper sheet is thin but not completely penetrated, and its light transmittance is larger than other parts of the paper sheet. These small ideas are called light transmission points, and the larger ones are called transparent curtains.
Mainly: whether the shape of the paper is good, the size is qualified, the quality of the packaging and the degree of damage.
Master the basic paper quality of paper. Including color, uniform flatness, flexibility, smoothness and cleanliness.
The approximate miss rate of lithographic paper (percentage of paper with obvious paper disease as a percentage of total paper) was examined.