At present, most of the packaging companies in China use two processes to produce color boxes: 1) First print the color tissue paper, then laminating or glazing, and then manually laminating or mechanically laminating the corrugated forming; 2) Color graphics It is printed on the plastic film and then covered on 100-card paper, and then mounted and formed.
Regardless of the process used to produce the color box and color box, its bearing pressure and compressive strength are much lower than the ordinary watermark carton of the same material (board line production), it is difficult to guarantee the quality when the customer urgently needs or rainy days, this problem is deep Deeply disturbing the producer, how to solve it?
Everyone knows: cardboard boxes are produced by glue coating, instant bonding after heating, and drying after forming; and the mounted color box cardboard boxes are not heated and dried, and the moisture in the glue penetrates into the paper, Coupled with the barrier of varnish and plastic film on the color surface, the moisture in the box blank will not be distributed for a long time, and it will naturally soften and reduce the strength. Therefore, we look for solutions to the problem from the following factors:
1 Paper matching
Some companies have such a misunderstanding: the greater the weight of the paper used, the greater the bearing capacity and compressive strength of the carton, but this is not the case. If you want to enhance the pressure bearing and compressive strength of the color box and color box, you must enhance the pressure bearing capacity of the core paper. As long as the facial paper does not show corrugated marks after laminating, you should try to use low-gram paper; core paper and tile paper are best used Straw pulp or wood pulp paper with good strength and high ring compression strength. Do not use medium-strength or general-strength tile paper, because it is mostly a mixture of raw pulp and regenerated pulp, which has fast water absorption, low ring compression strength, and good toughness but low stiffness. Through the test, the water absorption rate of medium-strength tile paper is about 15% to 30% higher than that of paddle paper by the Corbet method; the inner paper can increase the gram weight appropriately. Practice has proved that reducing the basis weight of inner paper and increasing the basis weight of tile paper and core paper has a more competitive advantage in terms of quality and price.
2 Quality of glue
Most of the carton production now uses corn starch glue made or purchased. High-quality corn gum not only has good bonding strength, but also enhances the bearing pressure and stiffness of the cardboard, and the box body is not easily deformed. The quality of corn starch glue is closely related to the production process, environment, quality of raw materials, mixing time, etc. It is well known that it will not be repeated.
The author only added the quality requirements of corn starch and the water ratio of starch glue, which are one of the main raw materials for rubber making, and the main materials. The main points are added. Reference points: The quality requirements of corn starch, the fineness is 98 ~ 100 mesh, and the ash content does not exceed 0.1%; Water content 14.0%; acidity 20CC / 100g; sulfur dioxide 0.004%; normal odor; white or slightly yellowish in color.
If the quality of gum starch does not meet this standard, the water ratio can be appropriately reduced according to the situation. As the temperature rises, the water ratio should be reduced accordingly, borax and caustic soda should be increased as appropriate, and the amount of hydrogen peroxide should be reduced. After the cooked glue is made, it should not be stored for a long time, especially in summer, it is best to use it with it. Add 3% to 4% formaldehyde, 0.1% each of glycerin and boric acid to the glue solution, which can increase the water blocking ability of the paper, accelerate the adhesion speed, and strengthen the cardboard hardness.
In addition to this, environmentally friendly chemical adhesives, namely PVA adhesives, can also be used when mounting sticker plates. Its characteristic is that the mounted corrugated cardboard is smooth, straight, good adhesion, and does not deform for a long time. Its production method is (take 100kg adhesive as an example): Material ratio: polyvinyl alcohol 13.7kg, polyvinyl acetate emulsion 2.74kg, oxalic acid 1.37kg, water 82kg water ratio 1: 6). First, heat the water to 90 ° C, add polyvinyl alcohol to stir well, continue to heat to boiling water, keep it warm for 3 hours, then add oxalic acid to stir, and finally add the polyvinyl acetate emulsion to stir and serve.
3 Glue amount
Whether it is manual or automatic mechanical mounting and pasting, the amount of glue should not be too large. In actual production, some employees in order to avoid degumming artificially increase the amount of glue, which is not desirable and must be strictly controlled. The amount of glue should be 80 ~ 110g / m2. However, depending on the corrugation size adjustment and grasping the amount of glue to uniformly coat the corrugated peak, as long as the glue is not degummed, the less glue the better.
4 Quality of single-sided cardboard
The quality of single-sided corrugated board is determined by the quality of the base paper, the corrugated type, the working temperature of the corrugating machine, the quality of the adhesive, the speed of the machine, and the operator's technical level. When the matching of the base paper is reasonable and the quality can meet the production requirements, it is necessary to check whether the corrugated roller corrugated peak of the single-sided machine is seriously worn. The normal corrugated type should be UV type. After a long period of use, due to factors such as sand in the paper or the hardness of the corrugated roller itself, the corrugated peak of the corrugated roller becomes semi-circular. The compressive strength is greatly reduced. In addition, if the pressure of the pressure roller is too high, the temperature of the corrugator is too high, which is easy to crack the corrugated single-sided cardboard. Similar single-sided corrugated paperboard has more glue when it is glued and mounted, and its physical properties change, which makes it difficult to ensure compressive strength.
In the case of normal raw material equipment, the preheater preheating area should be appropriately adjusted according to the moisture content of the paper, the temperature on one side should be controlled at about 200 ℃, and the pressure should be adjusted to about 0.3 ~ 0.4kPa (as long as the corrugated paper is not broken) No cracking, Riva paper fits well).
The vehicle speed control is low at the middle speed of the equipment design speed, and the viscosity of the adhesive is adjusted to 30 ~ 35S. If the adhesive precipitates yellowing water and smells, it should be updated immediately. The operator should be skilled and highly responsible. With good professional ethics, it can flexibly adjust the pressure and speed of each roller according to the actual production situation, so as to ensure the quality of single-sided corrugated cardboard.
5 Production environment
The temperature of the production environment should not exceed 33 ° C, and the air humidity should not exceed 45%. Otherwise, the cardboard is very easy to absorb moisture, and its own moisture cannot be evaporated, which naturally reduces the bearing pressure of the carton. In addition, it is best to rotate and shape the small box blank after 4h. Due to the urgent needs of customers, a blower can be used to force the air to promote the adhesion of the cardboard as soon as possible, to expel excess moisture.
In short, if you want to increase the pressure on the color box and color box, you must comprehensively analyze and consider it, and try to reduce various adverse factors. You must not lose sight of this, otherwise all efforts will be in vain.
