Automatic cardboard production line (or single-sided machine) technology for the production of starch adhesives

At present, the adhesive used in automated paperboard production lines (or single-sided machines) at home and abroad is commonly referred to as "raw rubber." The so-called "raw gum" refers to no adhesive force at room temperature, it will be heated to a mature gum by the high temperature on the paper, and it will have adhesive force. The production method mainly uses starch (mainly corn starch, and also other starches such as tapioca starch, wheat starch, etc.), and is made into adhesive by two-step method. The disadvantage of this type of pure starch adhesive is that the strength and hardness of the paperboard produced is not high, the moisture resistance is poor, and it is not water resistant.
The optimum viscosity of the automated cardboard production line (or single-sided machine) adhesive should be controlled between 45-95 seconds (measured with 4 cups), and of course between 30-300 seconds. Actually, manufacturers use a variety of habits. Differently, the viscosity of the glue used varies greatly, the minimum viscosity is about 30 seconds, and the maximum is about 300 seconds. Why is the best viscosity between 45-95 seconds? This is because: the viscosity is too small, the rubber roller is not glued, and when the double-sided compound is used, the permeation is too fast; the viscosity is too large, the fluidity is poor, the coating is uneven, and the permeation ability is not strong. In both cases, the adhesion is not caused. it is good. Therefore, in practical use, the viscosity of the glue should be controlled within a suitable viscosity range.
So how to adjust the viscosity of the glue? It should first understand what is the important factor affecting the viscosity of the glue and how it affects it. The influencing factors and impacts are as follows:
First, the carrier starch (or powder), viscosity; carrier starch (or powder) less, with less, the viscosity is small.
Second, the total water added, the viscosity is small; total water, viscosity.
Third, the use of borax, viscosity, large amount; low viscosity, low viscosity.
Fourth, the glue, the longer the mixing time, the smaller the viscosity; the shorter the stirring time, the greater the viscosity. In addition, under the same stirring time, the faster the mixer speed, the smaller the viscosity.
5. The use of caustic soda at a level below 3.5% of the total starch has little effect on the viscosity of the glue. If the amount of caustic soda is too large, the viscosity of the glue is extremely large and forms a mass that cannot be used.
Sixth, the viscosity of starch itself is also different. Starch contains branched and amylose, amylopectin, viscosity, amylopectin, and low viscosity. Different origins and different varieties of corn, containing amylopectin different processed starch, the viscosity is very small.
Usually, for a company, the equipment used for making glue must be constant, and the speed of the mixer must be constant. Due to the constraints of the production line, the water used for the glue is basically the same, that is, the amount of total water added is constant, and the amount of borax is also used. Invariable, so that in the actual process of making glue, only need to increase or decrease the amount of carrier starch, to master the appropriate mixing time, you can adjust the viscosity of the glue in the optimum viscosity range. If there is a change in the viscosity of the starch itself, it is only necessary to appropriately increase or decrease the amount of the carrier starch, so that the viscosity of the glue can be kept substantially constant.
When people talk about the viscosity of glue, it's easy to confuse it with good adhesion. Adhesive viscosity and adhesiveness are two different things. Viscosity and adhesion are two completely different concepts. In the case of adhesives for paperboard production lines, the viscosity of the glue does not substantially affect the bond strength over a wide range of viscosities. It is by no means the higher the viscosity of the glue, the higher the bond strength. On the contrary, it has good flowability and good permeability. , that is, the glue with small viscosity is used in high-speed automatic production lines, and the adhesive effect is better.
Different papers have different requirements for the viscosity of the glue, the paper is rough, easy to penetrate, the glue with a slightly higher viscosity is used; the paper is fine and the glue with a small viscosity is used. In particular, imported “cow cardboard” uses high-permeability plastics.
In different seasons, the temperature and humidity are different, and the requirements for glue are different. When the temperature is high and dry, the amount of water should be appropriately increased: when the temperature is low, the amount of water should be appropriately reduced. When the amount of water is changed, the amount of the corresponding carrier starch should be appropriately increased. Keep the viscosity of the glue basically unchanged. Here, the viscosity of the glue is basically the same, and it does not mean that the formula of the glue is not changed. On the contrary, the glue formulation should be changed according to different factors such as the paper, the season, and the viscosity of the starch itself, and it can be adjusted at any time, but it is not appropriate. Make big adjustments. Absolutely not changing formulas is not science. Different batches of starch may have different viscosity levels. If necessary, the formula should also be adjusted. It is only necessary to increase or decrease the amount of carrier starch.
In short, the plasticizers should make out the principles of plasticity according to actual needs, be flexible and flexible, and can arbitrarily adjust the viscosity of the plastic to meet the actual needs of cardboard production.