How to master the basic Paper of White Tipping Paper in printing

How to master the basic Paper of White Tipping Paper in printing

Paper defects that are not included in the technical requirements for paper quality may be referred to as paper defects. Paper disease includes both invisible and untouchable performance defects known only through experiment or printing, such as brittleness, through printing, hair loss, powder loss, etc., and also includes all kinds of defects and defects that can be seen or felt directly on the surface of the paper, such as dust and dirt. Here the latter is referred to as the paper appearance paper disease.

There are many diseases in the appearance of paper, such as dust, spots, net marks, wool marks, "cloud flowers", seersucker, wrinkles, creases, dirty spots, sod, transparent spots, warm spots, holes, embodiments, scars, pulp bumps, hard blocks, and quantitative unevenness, poor uniformity, etc. Some of these appearance paper diseases are brought into the paper before making paper, some are caused by poor technical operation or poor technology in the process of making paper, and some are caused by poor environmental hygiene in the factory. Once they appear, some appearance paper diseases are relatively continuous, such as wool marks and "cloud flowers", which will always exist if no measures are taken. Some appearance paper disease has a certain chance or interval long time only appear once, such as dirty spots, holes and so on. Some paper diseases exist, will make the quality of paper deteriorate, such as dust, wool marks, etc.; Some paper diseases make the paper become waste, such as offset printing paper with hard blocks or coated paper with big dirty points, can only be treated as waste.

According to different types of common paper diseases can be divided into:

Fluctuation of paper quantity and unevenness of paper width quantity

The first kind of fluctuation is generally caused by periodic vibration of the flow system of the paper material desiccating slurry box, shaking of the rotor screen in front of the slurry box or vibration of the slurry pump, and sometimes also caused by bending or unreasonable opening of the homogenate roller in the slurry box. The second kind of fluctuation is usually caused by unreasonable production process or improper operation management.

Poor evenness. The phenomena are as follows:

1) Clumpy organization: It refers to the state that fibers are mixed together into clumps.

2) "Cloud flower" : also called cloud structure, refers to the paper fibers like clouds distributed in the page.

3) Disconnection of fiber tissue: refers to poor fiber interweaving in the running direction of the paper machine.

4) Wavy fibrous tissue: It refers to the curved wavy thickened layer along the transverse width of the paper.

5) Paddle: refers to some longitudinal strips of paddle visible against the light on the paper.

Dust, specks, sand and hard lumps

1) Dust: It can be divided into "fiber dust", "non-metallic dust" and "metal dust".

2) Spots: can be divided into "wet spot and steam spot", "cylinder spot", "pressure light dark spot", "pulp spot", "bubble spot", "filler spot and paint spot", "bright spot and white spot".

3) Sand: refers to the existence of sand on paper, lime residue, carbon residue and other hard mineral sand.

4) Hard block: refers to the block material or coarse material that occasionally appears on the paper with a hard texture and is higher than the paper surface, such as wood joints, grass joints, pulp blocks, etc., which is the most harmful to printing.

Holes and curtains

1) Hole: It refers to the hole on the paper that is completely penetrated and has no fiber. Holes can be divided into pinholes, holes and holes according to their size.

2) Through curtain: it refers to the idea that the fiber layer on the paper is thinner but not completely penetrated, and its transmittance is larger than the other parts of the paper. The small ones are called light points and the large ones are called curtains.

Embossing and various impressions

1) Embossing: in the pressing process, the fiber tissue to form wet paper collapses under the action of too strong pressure, leaving scattered distribution, irregular shape, higher transparency and a lot of small pinholes on the paper. This phenomenon of wet paper being crushed by the pressing roll is called embossing. Severe embossing can easily cause the wet paper to break at the pressing part.

2) Streaks: stripes with a different gloss or color from the paper under the light.

3) Woolen cloth mark: refers to the impression of the warp and weft lines of papermaking woolen cloth on the paper.

4) Other impressions: net marks, watermark roll marks and vacuum roll marks, etc.

Folds and creases

1) Folding: refers to the folding or overlapping of the paper page to form a fold or crease. It can be divided into dead folding and living folding.

2) Warping and arching: warping refers to the state of the two sides or four corners of the paper warping, concave in the middle; Arch refers to the central part of the paper or the central part of the larger area of the arch, the two sides or four corners of the concave state.

3) Bubbling and bubble sand: bubbling refers to the local contraction of the paper page, resulting in protruding bubbles on the paper surface, and there are fine wrinkles on the paper around the bubbles; Bubble sand refers to the paper surface with a dense arrangement of small bubble spots

4) All kinds of wrinkles: according to the size and shape of different can be divided into curved wrinkles, fine oblique wrinkles, curled wrinkles, etc.

Other paper diseases

1) Cracks: cracks or breaks appear in the middle or edge of the paper page.

2) Paper edge is not neat, unclean: paper edge is not neat on the one hand refers to the paper after the page cut into a parallel line or rectangle, or the paper edge has rough edges, bending and twists, on the other hand refers to the cut out the whole selection of paper size is not flat or rewinding after the end face has "inside out into" phenomenon. Paper edge impurity refers to the paper page after cutting burr, serrated edge, mutilated edge and dirty edge.

3) Color inconsistency: it means that the whiteness and color of the same batch of products or even the same ream paper are inconsistent.

4) "lotus edge" : refers to the edge of the paper, especially the longitudinal edge of the lost due flat state, and the paper is not in the same plane bending state.

5) Obvious double-sided difference: with the naked eye, you can see the obvious difference between the two sides of the paper (except single-sided offset paper and single-sided coated paper).

6) Broken, broken and broken pieces of paper: broken and broken refers to incomplete paper, with missing corners, missing edges, broken or only half a piece of paper; Scraps of paper are small pieces of paper of varying sizes that are mixed in with paper.

The appearance quality of paper refers to the quality of paper that can be identified only by people's senses without instruments and equipment. It can be divided into the appearance quality of the page itself and the appearance quality of the piece paper formed by a sheet of paper or a long strip of paper.

No matter what kind of appearance quality affects the use of paper to varying degrees. Poor appearance quality will not only reduce the use value of paper and printing yield, but also make the paper waste. In addition, some serious appearance paper diseases, such as hard paper blocks, will also break the printing plate and cots during printing, resulting in damage to printing equipment. The appearance quality of paper is also closely related to its physical properties. For example, the appearance of seersucker paper, its smoothness and opacity will be affected to a certain extent.

Paper appearance quality inspection should achieve the following three purposes:

Check the finished quality of the paper. Mainly include: paper shape is good, size is qualified, packaging quality and damage degree.

Master the basic paper of paper. Including color, evenness, flexibility, tensile resistance, smoothness and cleanliness.

Sample detection of the approximate selection rate of flat printing paper (the percentage of paper with apparent paper disease).