How to increase the pressure on corrugated box color box

At present, most packaging companies in China use two kinds of processes for production of color boxes: 1) First, after the color paper is printed, it is covered with a film or glazed, and then manually tanned or mechanically automatically applied to the corrugated molding; 2) Color graphics It is printed on plastic film and then covered with a hundred card paper, and then molded.

Regardless of the color box color box produced by that process, its bearing pressure and compressive strength are much lower than those of ordinary watermark cartons of the same material (cardboard line production). It is difficult to guarantee quality in the event of a customer's urgent need or overcast days. This problem is deep. Deeply troubled producers, how to solve it?

Everyone knows that cardboard cartons are produced by gluing, heating and bonding, and drying. After molding, color box cartons are dried without heating. The moisture in the glue penetrates into the paper. In addition to the blockage of the glossy oil and plastic film on the color surface, the moisture in the box blank cannot be distributed for a long time, and the strength is naturally reduced by softening. So we look for ways to solve the problem from the following factors:

1 paper with

Some companies have such a misunderstanding: The greater the grammage of the inner paper, the more it can increase the bearing pressure and compressive strength of the carton. This is not the case. To increase the bearing pressure and compressive strength of the color box color box, it is necessary to enhance the core paper's pressure bearing capacity. As long as no visible traces of corrugating are found after the face paper is applied, low weight paper should be used; core paper and tile paper are best used. Grass pulp or wood pulp paper with good strength and high crush strength. Do not use medium-strength or strong-strength corrugated paper, because it is mostly a mixture of raw pulp and recycled pulp. It has fast water absorption, low ring pressure strength, and good toughness but low stiffness. After testing, the water absorbency of medium-strength stencil-matched pulp paper is about 15% to 30% higher than that of the medium-strength kraft paper; the gram weight can be appropriately increased in the paper. Practice has proved that reducing the weight of the paper inside and increasing the weight of the kraft paper and the core paper is a competitive advantage in terms of quality and price.

2 The quality of the glue

Most of the cartons used today are homemade or purchased cornstarch gums. High-quality corn glue not only has good adhesive strength, but also can increase the bearing pressure of the paper board, and it can be easily deformed. Advantages and disadvantages of corn starch glue are closely related to the production process, environment, quality of raw materials, mixing time, and so on.

The author only used one of the main raw materials for making rubber corn starch quality requirements and the ratio of starch glue water, add the main surface to introduce the point of reference: corn starch quality requirements, fineness of 98 to 100 mesh, ash content of not more than 0.1%; Water content 14.0%; acidity 20CC/100g; sulfur dioxide 0.004%; odor normal; color white or slightly yellowish.

If the quality of gelatinized starch does not meet this standard, the water ratio may be appropriately reduced depending on the situation. As the temperature rises, the water ratio should be reduced accordingly. Borax and caustic soda should be increased as appropriate. Hydrogen peroxide should be reduced in dosage. After being cured, it should not be put for a long time, especially in the summer. It is advisable to use 3%~4% of formaldehyde, 0.1% of glycerin, and boric acid to increase the water resistance of the paper, speed up the bonding speed, and enhance the cardboard. hardness.

In addition, eco-friendly chemical adhesives, ie PVA adhesives, can also be used in the decals. Its characteristic is that the corrugated corrugated cardboard is smooth, straight, adhesive, and durable without deformation. Its production method is (100kg of adhesive as an example): the ratio of materials used: polyvinyl alcohol 13.7kg, polyvinyl acetate emulsion of acetic acid 2.74kg, 1.37kg oxalic acid, and 1:82 water 82kg water ratio). Firstly, heat the water to 90°C, add the polyethylen burnt alcohol and mix well, continue heating until the water boils, keep warm for 3 hours, then add oxalic acid to stir, and finally add acetic acid and polyvinyl alcohol emulsion to stir and serve.

3 Coated amount

Whether it is manual or automatic mechanical paste color, the amount of glue should not be too large, some employees in the actual production in order to avoid degumming people to increase the amount of glue, which is inadequate, must be strictly controlled. The amount of glue should be 80~110g/m2. However, depending on the size of the corrugator, it is advisable to control the amount of rubber and evenly coat the peak. As long as it is not degummed, the smaller the amount of glue, the better.

4 Quality of Single Board

The quality of single-sided corrugated board is determined by the quality of the base paper, corrugated type, operating temperature of the corrugating machine, adhesive quality, machine running speed, and operator's skill level. When the base paper with a reasonable and quality can meet the production needs, it is necessary to check whether the single-sided machine corrugated roller peak wear. The normal enamel type should be UV type. After a long period of use, the peak of the corrugating roll will become a semicircle due to factors such as the sand content of the paper or the hardness of the corrugating roll itself. The compressive strength is greatly reduced. In addition, if the pressure roller is over-pressurized, the temperature of the tamper machine is too high, and the single-sided cardboard corrugated board is easily broken. When similar single-sided corrugated cardboard is used to glue, it is difficult to ensure the compressive strength.

In the case of normal raw material equipment, depending on the water content of the paper, the preheating area of ​​the pre-heater should be appropriately adjusted. The single-sided temperature should be controlled at about 200°C, and the pressure magnitude should be adjusted to 0.3 to 0.4 kPa (as long as the corrugated paper is not broken). No cracking, good Riva paper fit).

The speed of the vehicle is controlled at the medium speed of the equipment design speed is low, and the viscosity of the adhesive is adjusted to 30~35S. If the adhesive precipitated yellowish water has odor, it should be updated immediately. The operator must be skilled and highly responsible. With good professional ethics, the pressure and speed of each roller can be flexibly adjusted according to actual production conditions, so that the quality of single-sided corrugated cardboard can be guaranteed.

5 production environment

The temperature of the production environment should not exceed 33°C, and the humidity of the air should not exceed 45%. Otherwise, the cardboard can easily absorb moisture, and its moisture is not volatilized, which naturally reduces the bearing pressure of the carton. In addition, it is best to paste the small box blank and rotate it for 4 hours before forming. Due to the urgent needs of customers, fans can be forced to blow air to promote the adhesion of the cardboard as soon as possible and to drive off excess moisture.

In short, to increase the pressure on color box color box must be considered comprehensively and comprehensively, and try to reduce various unfavorable factors.

Author: Xiao Jing Single

Reprinted from: Packaging World