Basic knowledge of the hottest paper detection

Basic knowledge of paper testing

in the process of paper product trading, it is often necessary to check the quality of packaging. Today, the Chinese paper industry brings you into the basic knowledge that more than half of the products after the mass production of the paper project can be digested in situ, and into the areas that need attention in packaging acceptance

acceptance of paper outer packaging

at present, lithographic paper packaging mainly adopts two basic forms: wood plywood packaging and wood box packaging. Generally, the appearance of qualified lithographic paper is packed with more than two layers of wrapping paper, plus wood packaging, which is bound tightly with iron strips. The packaging paper used mainly includes wax paper, asphalt paper, kraft paper, snake skin paper, etc. The words "moisture proof", "do not throw" and other words are marked on the wooden plywood or wooden box, and some also indicate the thread direction of the paper. The quality certificate of the product shall also be pasted on the wooden plywood or wooden box, and the product name, specification, order weight, order number of each piece, paper grade, executive standard, production date, manufacturer name, etc. shall be indicated. The outer package shall be intact without deformation or damage. If the outer package is seriously damaged and the paper is exposed outside the package, you should not hesitate to reject it, or take other measures to avoid unnecessary losses. The acceptance of paper packaging is a basic acceptance, which must be strictly grasped

appearance acceptance after removing the outer packaging

after removing the outer packaging of the paper, first check whether there is a quality inspection sheet, and then check the paper phase and color of the paper

the basic feature of normal paper phase is good flatness, that is, the paper is correspondingly flat with flat end face. For a piece of paper, it is relatively difficult to judge whether the paper phase is normal, unless the paper has been seriously deformed

the usual method is to untie the paper bag and stack it 1m high to see whether the paper phase is normal. When the paper phase is abnormal, it shows a variety of shapes, including wavy and dished shapes. Other shapes include mountain shape, valley shape, angle warping shape, bag shape, inclined shape, valley shape, curl shape, saddle shape, etc

there are many reasons for these bad paper appearance, which can be summarized as follows: ① the whole paper size 7 Function of software permission classification processing: in order to ensure the safety of software and data, the water content is uneven, so in the experiment, the uneven local shrinkage of loading is controlled by deformation; ② Cleaning and cleaning of paper in the process of making paper: in the process of experiment, it is inevitable to produce some uneven thickness caused by dust; ③ The expansion and contraction of the front and back sides of the paper are inconsistent, especially for single-sided coated paper

in addition, it can be seen from the side of the stack whether the color of the paper is uniform. In any case, the paper supplied in the same batch must have consistent whiteness, uniform hue and small color difference. Otherwise, after the printed matter is bound into a volume, there will be obvious color stratification in the head, foot, incision and other parts

how to detect the paper size

the paper size should be measured by using a steel tape with a length of 2M and an accuracy of 1mm according to the national standard. During measurement, three samples shall be randomly taken from the same package, and the measurement results shall be expressed in all measured values, accurate to 1mm. The allowable error of paper length and size is ± 3mm. The deflection of the paper will cause insufficient or excessive paper size, resulting in the angle between the long side and the short side of the paper not at right angles. Therefore, in addition to measuring the length and size of the paper, the deflection of the paper should also be measured. The allowable deviation of paper deflection is 3mm~5mm

in addition, the size of paper size stability can also be expressed by the expansion rate of paper. The acceptance of paper can be measured by the elongation of paper in water. The cutting size is 2cm × A 20cm horizontal paper strip is soaked in water for 1h~2h to fully expand until the size remains unchanged. Take it out and lay it on the glass plate. Measure the size with a transparent ruler, calculate the elongation, and compare it with the standard

if the paper is bad after unpacking, and the elongation of the paper in water is too large, it is best to reject such paper to avoid future problems

how to detect the surface strength of paper

the surface strength of paper is a very important property of paper. Every kind of printing paper has certain requirements for it

therefore, the state has made clear regulations on the surface strength of each kind of printing paper

if the surface strength of the paper fails to meet the printing requirements, the paper will fall off wool, powder, and even delamination during printing. Therefore, the inspection of paper surface strength is also an important part of paper acceptance, but it is often ignored by many printing enterprises, so there are various printing faults during printing

when accepting paper, you can use some simple methods to judge the surface strength of the paper. For example, Danny raw wax stick method is used for testing. Although this method has some disadvantages, it is still a relatively simple method for determining the anti hair loss ability of a specific paper

when measuring, melt the end of a wax stick and press it on the surface of the paper to be measured. After 15 minutes, quickly pull it up and check the paper wool or paper powder on the end face. Another simple method is to press the slightly wet finger (usually the thumb) heavily on the surface of the paper, and quickly separate it after slightly rubbing, and observe whether there is short fiber or powder on the surface of the finger

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