Instructions for purchasing the hottest corrugated

Corrugated base paper purchase instructions

release date: Source: China Packaging

in order to attract more consumers' attention, more and more corrugated box manufacturers choose offset printing or preprint (flexo printing, gravure printing) to make corrugated boxes. However, due to the purchase of sick paper, the printing equipment was shut down, the corrugated box scrap rate increased and the customer complaint rate increased, which made the corrugated box production enterprises pay a painful price. Then, what are the paper diseases of the face paper used to make corrugated boxes (mainly gray background whiteboard, coated kraft paperboard, etc.). 7 What are the reasons for these paper diseases? 7 what impact will these diseases have on the printing process if you buy these diseased papers? 7 the author analyzes the common causes of corrugated base paper one by one in this paper, hoping to help corrugated box manufacturers identify the advantages and disadvantages when purchasing base paper

diagnosis of common diseases of corrugated paper

symptom 1: electrostatic

causes:

(1) in the process of paper making, the content of rosin is too high, while electrolytes such as aluminum sulfate and kaolin and other fillers are less. China produces high-voltage static electricity after drying and high-temperature and high-pressure treatment in Jilin, Cangzhou, Chongqing and other places

(2) during the printing process, if the paper itself contains less water, static electricity will also be generated in the process of mutual friction

(3) the paper is full in the paper warehouse. And the time is short, the water content in the paper is too late to reach balance

(4) the paper temperature (related to the ambient temperature of the paper warehouse) is quite different from the temperature of the printing workshop. Causes the paper to shrink. Generate physical static electricity

hazards:

paper with static electricity will be difficult to separate, and multiple sheets of paper will be formed during offset printing and enter the printing machine at the same time. In web printing, the same charges repel each other. There will be printing drift, overprint is not allowed, the paper is not neat, or it is difficult to pour paper

in addition, paper with static electricity is also easy to absorb dust and paper scraps in the air, making it adhere to the print, directly polluting the print. Sparks will occur when static electricity accumulates to a certain intensity. Bury fire hazards. When it is dry in winter. Such accidents are particularly likely to occur

symptom 2: hair loss. Reasons for powder dropping:

(1) improper slurry ratio or filling amount weakens the fiber adhesion

(2) the beating degree cannot meet the requirements

(3) the upper paper leaf fluctuates greatly and the uniformity is not good

(4) who will pay for these environmental protection materials when the pressing drum is set? " Not enough pressure

(5) there are attachments on the surface of the drying cylinder

(6) the temperature of the drying section is too high

(7) there is dust in the paper cutter. The knife is too blunt

(8) the moisture content of the finished paper is too low

harm:

paper wool and filler block the printing plate, affecting the normal production of the printing machine

symptom 3: fluctuation of paper quantity and uneven paper quantity

fluctuation of paper quantity includes quantitative fluctuation of paper longitudinal direction and quantitative fluctuation of paper direction. These fluctuations can be divided into periodic fluctuations and irregular fluctuations

main reasons for periodic fluctuation:

(1) due to the periodic

vibration of the conveying system from the paper material to the headbox

(2) vibration of rotor screen or slurry pump in front of headbox

main reasons for irregular fluctuations:

(1) unreasonable production process or improper operation

(2) the change of original pulp concentration causes the fluctuation of pulp forming concentration

(3) improper discharge operation of the beater caused poor mixing of the pulp pool

(4) the air mixed in the pulp withstands the paper

(5) the speed of the paper machine has changed

uneven sizing in the direction of the paper web refers to the inconsistent sizing along the width of the paper machine, that is, the thickness of half of the paper web. Half thin or one thick. A thin layer

main reasons:

(1) the paper is in the whole width of the headbox. The flow velocity at each point is not

consistent

(2) the opening of the starched lip is uneven or the lip is defective

(3) the edge setter causes the feeding material to be corrugated

(4) longitudinal grooved beam of copper

harm:

uneven paper weight will cause uneven printing pressure, resulting in uneven inking and inconsistent dot reduction

in addition to the above hazards, the uneven longitudinal quantification may also cause the printing cylinder and the embossing cylinder to collide with each other, shortening the service life of the machine and the printing plate

when carton manufacturers purchase base paper. A simple method can be used to check whether the paper quantity is uniform: observe whether the wet water line of the paper is neat. If the wet water line is very neat, it means that the paper quantity is relatively uniform. If the wet water line is seriously uneven, it means that the paper quantity may change greatly. Generally, the elongation of wet water line is higher. The quantity of the shortened wet water line is low

symptom 4: dust spots hard blocks

(1) dust: refers to exposure to the surface of cardboard or paper. All kinds of impurities with obvious color differences from other parts can be seen from any angle. It is divided into black dust and other dust

(2) spots: there is little difference between spots and dust. The main reason is that the gloss of the paper is inconsistent with the reflection. According to the characteristics of spots, they can be divided into wet spots. Cylinder spot. Calendering dark spots, slurry spots and bubble spots, filler spots, paint spots, bright spots and white spots. Where there are spots on the paper, the inking property is poor. The ink is not easy to absorb the printing color or the handwriting is inconsistent with other parts

(3) hard block: hard block refers to the hard lump and coarse-grained materials occasionally appearing on the paper, such as knots of wood and grass, pulp blocks, raw material blocks, etc. Hard block is very harmful to printing, it will damage the printing plate and blanket, and even cause serious damage to the printing machine. Large hard blocks on the paper may cause serious printing failures

symptom 5: poor uniformity

main reasons:

(1) in the process of helping parents locate their children's position, the size of long fibers is insufficient, and fewer cuts are made in the process of beating, so that the size in the fibers is intertwined into a mass

(2) the front box and table of the paper machine vibrate, and the insufficient dispersion of the fiber will also lead to poor uniformity

(3) in the printing process, the paper with poor uniformity will produce stress concentration under the tension of the printing machine, especially the roll paper printing machine, resulting in a high rate of paper breakage

a simple way to check for poor uniformity is to point the paper at a strong light source. The paper with poor evenness

will have flocculent clumps

symptom 6: crack

crack refers to a crack or breach in the middle or edge of the paper. These cracks or breaks 1:3 are easy to expand or be broken during the printing process, resulting in paper breakage and shutdown. Affect production efficiency. Increase paper loss

symptom 7: inconsistent tone

in the same batch of paper or even in the same color, there is the phenomenon of inconsistent whiteness and tone

in the paper

this phenomenon often occurs in some small and medium-sized paper enterprises. Because the whiteness of paper is different. There are obvious differences in the depth and shade of printed patterns. It's easy for customers to refuse

symptom 8: Ruffle edge

Ruffle edge refers to the edge of the paper. In particular, the paper loses its original straight state longitudinally. By observing the side of the paper, it is easy to find that the side of the paper with ruffles has irregular pores similar to honeycomb. When printing paper with ruffles. There will be inaccurate overprint and wrinkles. Fine folding phenomenon. Paper with severe ruffles cannot be printed on the machine. The above eight kinds of paper diseases are all problems that corrugated box manufacturers may encounter in the process of base paper procurement. If we can understand the causes and identification methods of paper defects, we can identify them in the procurement process and reduce unnecessary losses

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