The solution to increase the bearing pressure of c

2022-07-27
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Solution to increase the pressure on the color boxes of corrugated paper color boxes

release date: Source: China paper industry

at present, most of China's packaging and printing enterprises use two processes to produce color boxes: 1) first print color paper, then cover with film or polish, and then manually mount glue or machine automatically adhere to corrugated forming; 2) The color picture text is printed on the plastic film, then covered on the hundred card paper, and then mounted. No matter which process is adopted, the bearing pressure and compressive strength of color boxes are much lower than ordinary watermark boxes of the same material (produced by cardboard line). It is difficult to guarantee the quality when customers are in urgent need or in rainy days. This problem deeply puzzles producers. So how to solve it

as we all know, cartons produced by the cardboard line are formed by gluing, instant bonding by heating and drying; However, the pasted color box paperboard is not heated and dried. The water in the glue permeates into the paper. In addition, the gloss on the color surface and the plastic film block the water in the box blank, which can not be distributed for a long time. Naturally, it softens and reduces the strength. Therefore, we look for solutions from the following factors:

1 paper matching

there is a misunderstanding in some enterprises: the larger the gram weight of the paper inside, the more it can increase the pressure and compressive strength of the carton. In fact, it is not. In order to enhance the pressure bearing and compressive strength of color boxes, the pressure bearing capacity of core paper must be enhanced. As long as the surface paper does not show corrugation marks after laminating, low gram weight paper should be used as far as possible; It is better to use straw pulp or wood pulp paper with good stiffness and high ring compression strength for core paper and tile paper. Do not use medium strength or ordinary strong tile paper, because it is mostly a mixture of raw pulp and regenerated pulp, with fast water absorption, low ring pressure strength, good toughness but low stiffness. The test shows that the water absorption of medium strength tile paper is 15% - 30% higher than that of scribing paper by Cobb method; The weight of the lining paper can be increased appropriately. Practice has proved that although the weight of low inside paper was first used in 1967 to increase the weight of tile paper and core paper, it has more competitive advantages in terms of quality and price

2 quality of glue

most of the cartons are made or purchased corn starch glue. High quality corn glue not only has good adhesive strength, but also can enhance the bearing pressure and stiffness of the paperboard, and the box is not easy to deform. The advantages and disadvantages of corn starch glue are closely related to the production process, environment, quality of raw materials and auxiliary materials, mixing time, etc. as we all know, we won't go into details

the author only introduces the quality requirements of corn starch, one of the main raw materials for glue making, the water ratio of starch glue, and the appendixes. Reference opinions: the quality requirements of corn starch, fineness 98-100 mesh, ash content no more than 0.1%; Water content 14.0%; Acidity 20cc/100g; Sulfur dioxide 0.004%; Normal smell; The color is white or slightly yellowish

if the quality of gelatinized starch does not meet this standard, the water ratio may be appropriately reduced as appropriate. When the temperature rises, the water ratio should be reduced accordingly, borax and flake alkali should be increased as appropriate, and the amount of hydrogen peroxide should be reduced. The cooked glue should not be put away for a long time after it is prepared. Especially in summer, it is best to use it immediately. Add 3% - 4% formaldehyde, 0.1% glycerol and 0.1% boric acid into the glue solution to increase the water resistance of the paper, speed up the bonding speed and enhance the hardness of the paperboard

in addition, environmental friendly chemical adhesive, namely PVA adhesive, can also be used when mounting paperboard. Its characteristics are that the mounted corrugated board is flat, straight, well bonded, and durable without deformation. Its production method is (taking 100kg adhesive as an example): material ratio: polyvinyl alcohol 13.7kg, polyvinyl acetate lotion 2.74kg, oxalic acid 1.37kg, water 82kg, water ratio 1:6). First, heat the water to 90 ℃, add polyethylene glycol and stir evenly, continue heating until the water boils, keep the temperature for 3 hours, then add oxalic acid and stir, and finally add polyvinyl acetate lotion and stir evenly

3 gluing amount

whether it is manual or automatic, the gluing amount should not be too large. In actual production, in order to avoid degumming, some employees increase the gluing amount artificially, which is insufficient. They must strictly control the tensile strength, constant elongation, constant elongation force value and yield strength system. The glue amount shall be 80-110g/m2. However, it is appropriate to adjust the corrugation size and control the glue amount to evenly apply the corrugation peak. As long as there is no degumming, the less the glue amount, the better

4 quality of single-sided paperboard

the quality of single-sided corrugated paperboard is determined by the quality of base paper, corrugating type, working temperature of corrugating machine, adhesive quality, machine running speed and technical level of operators. When the base paper collocation is reasonable and the quality can meet the production demand, it is necessary to check whether the corrugating peak of the single-sided machine is seriously worn. The normal corrugation type should be UV type. After a long time of use, the corrugation peak of the corrugation roll will become semi-circular due to factors such as sand in the paper or the hardness of the corrugation roll itself. The compressive strength of the single-sided paperboard produced by the equipment under this condition will be greatly reduced. In addition, if the pressure roll is pressurized too much, the temperature of the corrugating machine is too high, which is easy to break the corrugating of single-sided paperboard. Similar single-sided corrugated board has more glue when gluing and mounting, and its physical properties change, so it is difficult to ensure the compressive strength

under normal conditions of raw material equipment, the preheating area of the pre potentiator shall be appropriately increased according to the water content of the paper, the temperature of one side shall be controlled at about 200 ℃, and the pressure of the pressure order shall be adjusted to about 0.3-0.4kpa (as long as the corrugated paper is not broken and the inner corrugated paper is well bonded)

the vehicle speed shall be controlled at a low medium speed of the equipment design speed, and the adhesive viscosity shall be adjusted to 30-35s. In case of any peculiar smell in the yellow water deposited by the adhesive, it shall be updated immediately. The operator shall ensure that the measurement technology of the two-way friction force generated during the ball disk test and the reciprocating test is skilled, with a high degree of heart and good professional ethics, It can measure the displacement according to the actual production situation: adopt 2000p/r high-precision photoelectric encoder and precision lead screw to rotate coaxially to adjust the pressure and speed of each roller, so as to ensure the quality of single-sided corrugated board

5 production environment

the temperature of the production environment should not exceed 33 ℃, and the air humidity should not exceed 45%. Otherwise, the cardboard is easy to absorb moisture, and its own moisture cannot be volatilized, which naturally reduces the bearing pressure of the carton. In addition, it is better to rotate the small box blank for 4H before forming. Due to the urgent need of customers, the blower can be used for forced blowing to promote the bonding of paperboard as soon as possible and remove excess moisture

in a word, if you want to improve the pressure bearing force of the color box, you must comprehensively analyze and consider, and strive to reduce various adverse factors. You can't ignore one thing and lose the other, otherwise all efforts will be in vain

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