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Paper packaging acceptance of flat paper

Time:2023-08-25 Views:772
1) Acceptance of paper packaging

At present, flat paper packaging mainly adopts two basic forms of wooden splint packaging and wooden case packaging. Qualified flat paper, the appearance of the packaging generally have more than two layers of wrapping paper, plus wood packaging, tied with iron strips. The main wrapping paper used are wax paper, tar paper, kraft paper, snake paper and so on. Indicate "moisture-proof", "do not throw" and other words on the wooden splint or wooden box, and some also indicate the direction of the paper. The certificate of the product should also be affixed on the wooden splint or wooden box, and the product name, specifications, ream weight, ream number per piece, paper grade, implementation standard, production date, name of the production enterprise, etc. The outer packing should be intact, without deformation or damage. If the outer packaging is seriously damaged and the paper is exposed to the packaging, it should not hesitate to reject it or take other measures to avoid unnecessary losses. The acceptance of paper packaging is a basic acceptance, we must strictly grasp this threshold.

2) Acceptance of appearance after removal of 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.

The basic characteristic of normal paper phase is that it has good flatness, that is, the paper is correspondingly flat and the end face is flat. In the case of a piece of paper, whether the paper phase is normal is relatively difficult to judge, unless the paper has produced serious deformation. The method usually taken is: unpack the paper package and pile 1m high to see whether the paper phase is normal. When the paper phase is abnormal, it takes on a variety of shapes, including wavy and saucer-shaped ones. Other shapes mountain shape, valley shape, corner shape, bag shape, inclined shape, valley shape, roll shape, saddle shape and so on. There are many reasons for these bad paper phases, which are summarized in the following aspects: (1) The water content of the whole paper is not uniform, which presents an uneven local contraction; The thickness of the paper formed in the paper making process is not uniform; ③ The front and back of the paper are inconsistent, especially single-sided coated paper is more obvious.

In addition, from the side of the paper pile can also see whether the color of the paper is uniform. In any case, the same batch of supplied paper must be consistent in whiteness, uniform in tone, and small in color difference. Otherwise, after the printed matter is bound into a book, the top, the footing, the incision and other parts will look like there will be obvious color stratification.

3) Examination of single sheets

Randomly extract a piece of paper from the paper pile to check whether it has appearance paper disease and its uniformity. Touch the surface of the paper with your hand or look at the paper horizontally to check the level of uniformity and cleanliness of the paper surface. In general, the surface of the paper should be flat, no traces, no bumps, while the surface of the paper should not be light and dark, reflective spots, or have dust inconsistent with the color of the paper. Hold the paper up to the light and check the uniformity of the paper. When observing the light, the paper should not have light or dark, varying degrees of light or transparent points. If the paper appears a large area of uneven cloud spots, it indicates that the uniformity of the paper is very poor, which will seriously affect the quality of the printed product.

4) Take 4 to 5 pieces of paper for inspection

Plate paper is sometimes made of multiple web paper simultaneously cut and stacked, due to the subtle differences in the papermaking process of different web paper, resulting in differences in the nature of several adjacent papers in the same pile. If one of them is mixed with an unqualified web, then a circulating abnormal phenomenon will occur, and there will be a printing failure at a certain interval when printing. Therefore, it is necessary to continuously extract several pieces of paper in the paper pile for comparative inspection to check whether there is such a difference between adjacent papers. Although this case is relatively rare, but sometimes this observation and analysis is particularly important, we must pay attention to the accumulation of experience in this area.

5) Acceptance of paper size

The measurement of paper size according to the national standard should use the length of 2m, accuracy of 1mm steel tape measurement. When measuring, 3 samples should be arbitrarily selected in the same package, and the measurement results are expressed as all the measured values, accurate to 1mm. The allowable error of paper length 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 is not right Angle. Therefore, in addition to measuring the length and size of the paper, the skew of the paper should also be measured. The allowable deviation of paper skew is 3 ~ 5mm.

6) Check whether the quantity of paper is consistent with that marked by the manufacturer

Cut 5 200×250mm paper samples with a paper cutter, weigh them on a balance with higher sensitivity, and then divide the measured mass by the area of the paper, the obtained value is the quantitative value of the paper. The measured results should be very close to the quantity marked on the product certificate, and the quantity can fluctuate within the range allowed by the national standard, but cannot exceed this range.

7) Acceptance of paper dimensional stability

The size of the paper size stability can be expressed by the expansion rate of the paper. When accepting the paper, it can be measured by the elongation of the paper in water. Cut a horizontal strip of 2×20cm and soak it in water for 1 ~ 2h, make it fully expanded until the size remains unchanged, take it out and lay it on a glass plate, measure the size with a transparent ruler, calculate the elongation, and compare it with Table 1.

If the paper is already a bad paper phase after opening the package, and the elongation of the paper in water is too large, it is best to reject such paper to avoid future problems.

8) Acceptance of paper surface strength

Paper surface strength is a very important property of paper. Each type of printing paper has certain requirements for it. Therefore, the state has made clear provisions on the surface strength of each type of printing paper. If the surface strength of the paper fails to meet the requirements of printing, then the paper will produce hair loss, powder removal, and even stratification when printing. Therefore, the inspection of the surface strength of the paper is also an important part of the acceptance of the paper, but many printing companies often ignore it, so that a variety of printing failures occur when printing.

When accepting the paper, some simple methods can be used to judge the size of the surface strength of the paper. If using Danny wax rod method test. Although this method has some shortcomings, it is still a relatively simple method to determine the anti-hair loss ability of a particular paper. When measuring, melt the end of a grade wax rod and press it onto the surface of the paper to be measured, pull it up quickly after 15min, and check the paper wool or paper powder uncovered on the end face. Another simple method is to use a slightly wet finger (usually the thumb) pressed heavily on the surface of the paper, and then quickly separated after a little kneading, and observe whether the finger surface is stained with short fibers or powder.

In short, in the absence of testing instruments, the quality of flat paper can be judged by the above methods. Of course, if you want to accurately measure the quality indicators of the paper, you must have special instruments and equipment, and also in a certain experimental environment, here is no longer detailed.
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