Summary of the most popular corrugated board bondi

2022-07-24
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As we all know, to solve the problem of poor adhesion of corrugated board, we not only need to have a deep understanding of the bonding and forming principle of the board, but also do not need to have a deep research on the operation characteristics of the board production equipment, so as to achieve the most ideal product quality with the best process plan and make the board production line operate with high speed, high efficiency and high quality

the topic of this issue focuses on the bonding link of corrugated board production to open a channel for you to produce high-quality cardboard

solve the problem of "poor adhesion" and improve the quality of paperboard

in the production practice of corrugated boxes, the adhesion between various papers is a very important link, and to a certain extent determines the quality level of products. The quality of corrugated board is directly affected by the tightness and firmness of the bonding between each layer of paper. The corrugated board with good adhesion has flat surface, no blister, no wrinkle and no warpage. After being processed into a corrugated box, there will be no separation between the paper sheets, and the appearance is rigid. It has good compression resistance and cushioning performance, which can effectively protect the inner goods from being damaged by external adverse factors. However, in the corrugated board production line, the phenomenon of poor adhesion of corrugated board (foaming, degumming, false particles) occurs from time to time. It is understood that nearly 70% of the waste and substandard products produced by the corrugated board production line are caused by adhesion problems. Therefore, in order to really achieve the purpose of cost reduction and efficiency increase, the scrap rate caused by the bonding problem must be controlled within an appropriate range. Next, we will find out the causes of "poor adhesion" of cardboard, and provide a series of solutions for you when you encounter problems in actual production

the electronic universal testing machine is an important index for the physical performance test of corrugated board for the operation of the machine tool. The reasons that affect the bonding strength of corrugated board are complex. Generally speaking, base paper, adhesives, corrugated board machinery, production planning and staff operation level all exert influence on it. And the above factors will affect each other

(I) base paper

is mainly manifested in several aspects:

moisture content of base paper: too dry (less than 6%) or too much moisture (more than 12%) of carton paper or corrugated base paper will cause poor adhesion of corrugated board. When it is too dry, the swelling of the adhesive and the water necessary for bonding are absorbed by the base paper, resulting in the gelatinization of the adhesive. When the moisture is too large, the excess moisture absorbs the heat, resulting in insufficient heat and poor adhesion. The solution is to strictly control the moisture of the base paper. If it is too dry, it must be sprayed with moisture. If the moisture is too large, the moisture and preheating area of the base paper must be appropriately increased. If the effect is still poor, the paper must be changed

water absorption or water permeability of base paper: the material, tightness and sizing degree of base paper determine its water absorption or water permeability. Base paper with poor water absorption or permeability will inhibit the penetration of adhesive. Base paper with strong water absorption or permeability will cause gelatinization and penetration. The former solution is to use additives in the adhesive to improve the hydrophobic properties of the base paper surface and make the adhesive penetrate. In addition, it is necessary to properly increase the coating amount of adhesive. As we all know, the bonding of corrugated board is first to apply glue to the corrugated peak, and then to combine with the surface paper or sandwich. The transfer of adhesive between any layer is hindered, which will affect the bonding effect. 2. The safety device of the electronic tensile testing machine, for example, the class a straw pulp corrugated paper of a company, after re sizing, has poor water absorption, and cannot be well bonded without the use of water-resistant adhesives. The latter solution is to properly increase the viscosity of the adhesive

breaking length of base paper: it is the ratio of the strength of the base paper to the quantity, indicating the length required for a certain width of paper strip to be broken by its own weight. If the base paper breaking length is low, it is bound to cause frequent paper breaking and shutdown when the tile linear speed reaches a certain degree. At this time, the corrugated board staying in the drying channel absorbs too much heat, which helps to confirm the heat of the powder material suitable for the multi jet fusion technology. No matter how good the adhesive is, it cannot be well bonded. In this case, the solution is to reduce the machine speed or improve the quality of the base paper, and include the breaking length into the base paper inspection items

the base paper is loose at one side: if the corrugated paper is loose at the other side, it will cause uneven corrugation and affect the adhesion with the paperboard; If one side of the paperboard is loose, wrinkles will be formed on the surface of the paperboard. Poor adhesion is formed in severe cases. The only solution is to replace the base paper

(II) quality of adhesive

mainly reflects two aspects: one is the quality of starch, and the other is the quality of adhesive manufacturing process

the low grade of starch means that the processing fineness is poor, and there are many impurities such as protein, fat and ash. Using such starch, first, it will consume more sodium hydroxide, making the adhesive unstable. The bonded corrugated board is easy to absorb moisture. If it is placed in a humid environment for a short time, it will degumm the corrugated board; Second, the adhesive is easy to produce gel with large starch particles and impurities as the core, which makes the fluidity of the adhesive worse and the coating uneven, making the corrugated board locally free of glue and less glue, resulting in poor adhesion. The solution is to use high-quality starch. If it is corn starch, it is better to use industrial grade I or above. The quality of the adhesive production process is more important. The adhesive of corrugated board has appropriate solid content, viscosity and necessary gelatinization temperature. In general, the viscosity of the adhesive tends to decrease every time it passes through the circulating pump. At this time, the newly prepared adhesive shall be added for mixing

in addition, during the shutdown on holidays, the excess adhesive is stored in the storage tank. Especially in hot summer, the bacteria decompose the starch and cause corruption, resulting in a sharp drop in viscosity and starch precipitation, resulting in poor adhesion. The solution is to add preservatives such as formaldehyde, 0.35kg per 200kg of starch, or 0.32kg per 200kg of sodium pentachlorophenol, when preparing the adhesive

when making water-resistant paperboard, high-grade paperboard and corrugated paper are often used together with water-resistant adhesives. Generally, the polymerization and condensation of this kind of adhesive with thermoplastic resin can still be carried out, and sometimes the viscosity rises sharply, which is not suitable for the service conditions of corrugated board machine. The solution is to readjust the glue quantity to make the viscosity meet the use requirements

when the quantitative closing tightness of face paper or even sandwich paper is high (the quantitative closing tightness is more than 180g/m2, and the tightness is more than 0, 70g/m3), sometimes poor adhesion is caused by insufficient heat. Because the face paper with higher quantitative content is thicker, and the face paper with higher tightness is dense, which affects the heat transfer, while the heat transfer of a corrugated takes more time, resulting in poor adhesion between single-sided a corrugated and sandwich paper. The solution to this situation is to reduce the machine speed and increase the wrapping angle of thick paper and pre heater

if the absolute heat of the corrugated board machine is insufficient, it is also a good way to use an adhesive with low gelatinization temperature. When the weight of tissue paper is low (less than 180g/m2), it is easy to produce bubbles on the surface of tissue paper, which is called "blisters", which is a local degumming phenomenon. This phenomenon will occur on one side of the paperboard after a short time on the double-sided corrugated paperboard machine or loading the paperboard on the trolley. The situation is mainly caused by the large moisture content of the faced paperboard or the drying of the corrugated paperboard. Due to the imbalance of heat and moisture, the excessively dry corrugated board absorbs moisture at the outlet of the double-sided corrugated board machine. Since it has been fixed longitudinally, it stretches laterally and forms a small bubble on the surface. In addition to reducing the amount of adhesive as much as possible, cutting off part of the heat of the hot plate or increasing the machine speed is also a way to make adhesives with high solid content and low viscosity, but we must master the gelatinization temperature

(to be continued)

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