1、 Calibration of adhesives
1. Why calibrate?
In the process of controlling the amount of glue, it is easy to ignore a very important problem. Different types of adhesives produced by different manufacturers have different properties, that is, the results obtained by using the same composite process are also different. It mainly includes two aspects
(1) The relationship between the amount of glue and the composite strength. The same amount of glue, composite strength is the same? The greater the amount of glue, the better the composite strength?
(2) The effect of the amount of glue on the residual solvent. Considering the above two factors, it is necessary to calibrate each adhesive, otherwise, on the one hand, it will increase the cost unnecessarily, on the other hand, it is easy to have quality problems.
2. How to calibrate?
The first step: according to the product structure to determine the appropriate amount of glue, this is very important. In view of a certain product structure, the selected adhesives are calibrated respectively to determine the amount of glue required to ensure the quality of the composite products. At the same time, we can compare which adhesive has better operability and can save cost.
The second step: determine the working solution concentration or calibrate the working fluid viscosity. After selecting the amount of glue, it is necessary to consider all kinds of influencing factors according to the actual situation, including the performance of the laminating machine, the number of lines of the existing coating roller and the depth of the mesh hole, and the environment of the workshop to determine the concentration or viscosity of the working fluid.
Many factors affecting the amount of glue can be divided into two categories: easy to control factors and variable factors. Easy to control factors include the number of lines of the coating roller, the depth and shape of the mesh hole; the hardness and pressure of the pressure roller; the angle, position and pressure of the scraper; and the compound speed. The variable factors include the manufacturer, model, solid content, original viscosity and fluidity of the adhesive, and the temperature and humidity of the environment.
But how can we control the factors easily?
(1) If the working solution concentration is used as a parameter to control, it depends on the liquid operability, fluidity difference and transfer rate when the concentration is 30% or 40%.
(2) If the viscosity of the working fluid is used as a parameter to control, the working concentration of each adhesive under different viscosity should be calibrated first, because the final sizing amount (dry basis) is determined by the working fluid concentration, not by the viscosity. Then determine the coating roller, cot and other easy to control factors.
3. Function of calibration
The process of adhesive calibration is actually a comparative process. Through the calibration, we will find that the higher the price of the adhesive, the higher the use cost, sometimes the opposite may be true.
2、 Contrast test of glue amount
As mentioned above, the static calibration before the use of adhesive, the control of glue amount and cost in the production process is the main. A reasonable amount of glue is to ensure the performance and quality of the composite products without additional cost.
(1) In high working fluid concentration, if the fluidity of the adhesive is not good, it will increase the chance of appearance quality problems of white spots.
(2) High concentration of working solution can save solvent, but if the coating roller has a deep hole, it will also increase the amount of glue.
3、 Calibration methods and precautions
The law of glue quantity and cost control is summarized as follows:
(1) It is scientific and practical to use the viscosity of working fluid as a monitoring parameter to control the amount of sizing after the concentration of working solution is determined.
(2) High viscosity and low cost can be used.
(3) High concentration gluing can be selected, but high viscosity or low viscosity should not be selected. Generally, when the viscosity is controlled within 15 ~ 20s, the transfer effect of glue solution is the best.
(4) When the working solution concentration is high, the coating roller with shallow mesh hole can be considered.
(5) Attention should be paid to the influence of temperature and humidity on viscosity, especially the manufacturers in the north. If necessary, mark summer and winter separately.
Dongguan Beite packaging materials Co., Ltd. - located in Dongguan City, the world's manufacturing city, is a subsidiary of Beite packaging (China) Co., Ltd., with a plant area of 6000 square meters. It is a flexible packaging enterprise integrating R & D, production and sales. It has a complete set of domestic advanced production equipment, a scientific and humanized management system and a group of experienced technical personnel For backing, to provide customers with quality products and first-class service.
The company produces composite bags, roll film, fruit bags, aluminum foil bags, suction mouth bags, self-supporting bags, zipper bags, anti-static bags, special-shaped bags, etc., which are suitable for the internal and external packaging of food, daily chemicals, electronics, toys, medicine, cosmetics, industrial products and other industries.
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