Application of starch adhesive for the hottest pap

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Application of starch adhesive for paperboard production line at present, the adhesive used in automatic paperboard production lines (or single-sided machines) at home and abroad is commonly known as "raw glue". The so-called "raw glue" means that there is no adhesive force at room temperature. Only when the high temperature on the paper heats it into mature glue, can there be adhesive force. The preparation method mainly uses starch (mainly corn starch, but also cassava starch, wheat starch and other starches) to prepare adhesive by two-step method. The disadvantage of this kind of pure starch adhesive is that the strength and hardness of the produced paperboard are not high, the moisture resistance is poor, and the water resistance is not good

the optimal viscosity of adhesive for automatic paperboard production line (or single-sided machine) should be controlled between 45-95 seconds (measured by coating 4 cups), of course, it can also be used between 30-300 seconds. In fact, various manufacturers have different usage habits and different formulas. 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 belt can not be glued, and the penetration is too fast when double-sided compounding; The viscosity is too large, the fluidity is poor, the gluing is uneven, and the permeability is not strong. Both of these conditions can cause poor adhesion. Therefore, in actual use, the viscosity of the adhesive should be controlled within the appropriate viscosity range

how to adjust the viscosity of the glue? First of all, we should understand what are the main factors that affect the viscosity of the adhesive and how they are affected by the computer to realize electronic measurement and automatically complete the compressive strength experiment. The influencing factors and conditions are as follows:

first, the amount of carrier starch (or rubber powder) is large and the viscosity is large; The amount of carrier starch (or rubber powder) is small and the viscosity is small

2. More total water is added and the viscosity is small; The total water is less, and the viscosity is based on solving the problem of being controlled by others

III. large amount of borax and high viscosity; Low dosage and viscosity

IV. the longer the mixing time, the smaller the viscosity; The shorter the mixing time, the greater the viscosity. In addition, when the mixing time is constant, the faster the mixer rotates, the smaller the viscosity

v. if the amount of caustic soda is less than 3.5% of the total starch, it has little effect on the viscosity of the glue. If it is too much, the viscosity of the glue will be very high and it will form a cluster and cannot be used

VI. the viscosity of starch is also different. Starch contains amylopectin and amylose, amylopectin, viscosity; Less amylopectin and low viscosity. The amylopectin content of corn from different producing areas and varieties is different, and the viscosity of the processed starch is different

generally, for an enterprise, the glue making equipment is fixed and the speed of the mixer is fixed. Due to the conditions of the production line, the water content of the glue used is basically unchanged, that is, the total water migration amount is unchanged, and the amount of borax is also unchanged. In this way, in the actual glue making process, the viscosity of the glue can be adjusted arbitrarily only by increasing or reducing the amount of carrier starch and mastering the appropriate mixing time, Keep it within the optimum viscosity range. If the viscosity of the starch itself changes, it is only necessary to increase or reduce the amount of the carrier starch to keep the viscosity of the adhesive basically unchanged

when people talk about the viscosity of adhesive, it is easy to confuse it with the quality of adhesion. The viscosity of glue and the quality of adhesion are two different things. Viscosity and adhesion are two completely different concepts. For the adhesives used in the paperboard production line, within a large viscosity range, the viscosity of the adhesive basically does not affect the bonding strength. It is by no means that the greater the viscosity of the adhesive, the higher the bonding strength. On the contrary, it has good fluidity. That is, the adhesive with small viscosity can be used in the large high-speed automatic production line, and the bonding effect is better

different papers have different requirements for the viscosity of the glue. The paper is rough and easy to penetrate, and the glue with slightly higher viscosity shall be used; The paper is fine and dense, and the glue with smaller viscosity shall be used. In particular, imported "Kraft linerboard" shall be applied with glue with high permeability

in different seasons, the temperature and humidity are different, and the requirements for glue are different. If it is warm and dry, the total amount of water shall be appropriately increased; In case of low temperature and humidity, the amount of water shall be appropriately reduced. When the amount of water changes, the amount of the corresponding carrier starch should be appropriately changed to keep the viscosity of the glue largely unchanged. The glue viscosity mentioned here is basically unchanged, which in no way means that the glue making formula is unchanged. On the contrary, the glue making formula should be properly adjusted according to the paper, different seasons and the viscosity of the starch itself, but should not be greatly adjusted. It is not science to never change the western language. The viscosity of different batches of starch may be different. If necessary, the formula should also be adjusted, just increase or decrease the amount of carrier starch

in a word, the glue making personnel should understand the glue making principle, use it flexibly according to the actual needs, and can arbitrarily adjust the glue to check whether the governor destroys the viscosity, which can meet the actual needs of paperboard production. China Packaging News

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