Discussion on two gluing methods in the composite

Discussion on two gluing methods in honeycomb paperboard compounding

in the process of honeycomb paperboard compounding, there are two gluing methods: the first is paper gluing, and the second is paper core gluing. " The surface paper has high adhesive rate and less degumming, but the cardboard has high moisture content, and the finished product can be processed only after drying; The adhesive rate of the paper core is poor, and it is easy to produce defective waste products, but the moisture content of the paperboard is low, so it can enter the subsequent processing after being off the machine

honeycomb paperboard is composed of upper and lower paper and paper core sandwiched in the middle. The surface paper and paper core are bonded with adhesive. The so-called cardboard quality, in addition to the advantages and disadvantages of paper material and paper core factors, is the bond fastness. If the cardboard has no degumming, it is a high-quality product, otherwise it is a defective product and waste product

honeycomb paperboard and corrugated paperboard are paper products, and their adhesives are also of the same kind. Generally, modified starch is used. In addition to being cheap, modified starch also has the advantages of high viscosity and good toughness. When the modified starch glue meets the paper, the glue first penetrates along the fiber layer of the paper. The face paper is connected with the paper core and gelatinized, so that the original raw starch is steamed at high temperature, and the viscosity of the glue is improved. After flattening again, the adhesive film begins to solidify. At this time, the paperboard cannot be moved at will. It should be stacked and compacted immediately. After the adhesive liquid is completely solidified and its interface bonding is firm, the paperboard compounding is over

in the process of honeycomb paperboard compounding, there are two gluing methods: the first is surface paper gluing, and the second is paper core gluing. The surface paper has high adhesive rate and less degumming, but the cardboard has high moisture content, and the finished product can be processed only after drying; The adhesive rate of the paper core is poor, and it is easy to produce defective waste products, but the moisture content of the paperboard is low, so it can be processed after being off the machine

face paper gluing method

face paper gluing method is to apply adhesive on the upper and lower layers of face paper. When compounding, the facade of the paper core coincides with the face paper, and the glue liquid on the face paper also helps to apply to the facade of the paper core. The face paper and the paper core are bonded together. At this time, with the forward movement of the machine or the manual stacking after getting off the machine, even if the face paper of the paper core is slightly misplaced, because the face paper is coated with glue liquid, the paper core will stick wherever it moves, So the cardboard will not degumm. However, due to the large-area gluing of the upper and lower paper, the water in the glue liquid quickly enters the paper and is sealed in the bee hole, so the moisture content of the paperboard is very high. Without drying equipment, whether it is dried outdoors or indoors, due to the different heating on both sides of the paperboard or uneven air flow, the warpage and deformation of the paperboard can be caused. Therefore, to adopt the method of surface paper gluing, an oven must be added to the equipment, and the paperboard must travel under the condition of flat pressure in the oven

paper core gluing method

paper core gluing is to apply glue on the elevations on both sides of the paper core. When the paper core is compounded with face paper, the glue on the elevation of the paper core can also be applied to the face paper. At this time, the compounding must not be shifted, because there is little glue on the elevation of the paper core. When compounding, a part of the glue has been applied to the face paper, and there is little glue left on the elevation. After shifting, it must be applied to another part of the face paper, Too little glue will make the composite paperboard degummed. To this end, the pre pressing paper core conveyor roll of the paper core stretching machine of the honeycomb paperboard production line can be transformed into a knurled knife shape, with a spiral spacing of about 2mm and a depth of 1.5mm. A hole with a depth of 0.5 ~ 0.8mm is cut on the facade of the paper core, and this hole is pressed into a "1" shape. In this way, the treated paper core will not only not bear the flat pressure, but also increase the amount of glue applied on the facade of the paper core, and at the same time, when combined with the face paper, it will increase the adhesion area, Thus, the purpose of adhesion and fastness is achieved. The amount of glue on the paper core is about one-third of that on the face paper. Therefore, in order to achieve better bonding effect, the adhesive on the paper core should be used as frequently as possible. Select high-quality products with small amount and low cost, and the efficient adhesion just makes up for the lack of easy degumming

no matter whether the surface paper is glued or the paper core is glued, the moisture in the paper core must be dried first, because the moisture in the adhesive strip of the paper core under the paper core line is in the paper core, and the moisture rarely runs out of the paper fiber after compaction and cutting, so it must be baked after stretching. When the moisture in the paper core is reduced, the moisture in the bee hole will also be reduced during compounding, which is very beneficial to the drying of the paperboard

the paperboard is dry

the adhesive on the surface paper is good, but the moisture content of the paperboard is high; The adhesive adhesion on the paper core is poor, but the moisture content of the paperboard is low. In order to bond the paperboard well and have low water content, the baking oven must be added for the surface paper gluing method, and the paper core gluing method must be reformed into the paper pressing conveying roller, which is the reality that the domestic honeycomb paperboard assembly line must be improved at present. However, the general situation is that more than 90% of the assembly lines still maintain the glue on the face paper, and the moisture content of the paperboard off the machine remains high. These enterprises prefer to turn the sun, and are rarely willing to improve the equipment, which directly affects the quality of paperboard and subsequent processing

the drying of honeycomb paperboard is indeed a thorny problem, because all the water is sealed in the honeycomb hole. When the paperboard is heated, the water in the honeycomb hole will go out of the paper fiber, a small part of it will go into the atmosphere through the face paper, and most of it will enter the space in the honeycomb hole and cannot be dispersed. As soon as the temperature is reduced, the water vapor in the honeycomb hole will be absorbed by the surrounding paper, and the moisture content of the paperboard is still very high. It must be repeated many times before the paperboard can be dried. Therefore, the cardboard produced in the early assembly line, some of which were punched on the face paper and some of which were slotted on the paper core, failed. Someone once imagined that the paper core was first bonded with a layer of paper by the method of paper lamination, and then the moisture was dried in the oven, and then another layer of paper was compounded. This idea changed the traditional process. However, manufacturers of honeycomb paperboard assembly line are unwilling to eat "crab" first, because this is a "risk" measure. There are not only many technical problems, but also the risk of economic loss. From the perspective of stability, it is better to improve the two glue methods of traditional technology

(Liu Chongwen)

source: Shanghai packaging

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