How to improve the quality of corrugated paperboar

How to improve the quality of corrugated board

in recent years, China's corrugated box industry has experienced the most difficult period in history. Due to the low threshold of this industry, the number of enterprises investing in this industry will continue to increase. At the same time, some powerful international paper groups have entered or are entering the Chinese market, and competition will be the main theme of the future market. Only by constantly improving their own technical level can they provide customers with high-quality carton packaging products and occupy a place in the international competition field of corrugated carton packaging

the goal of every carton enterprise with a cardboard production line is to produce corrugated cardboard that is beautiful, flat and excellent in all test indicators. However, due to the reasons of equipment and operators, a considerable proportion of enterprises in the carton industry produce products with unsatisfactory quality. With the development of corrugated box packaging in the direction of "low weight, light weight and high strength", the quality requirements of corrugated board are becoming more and more strict. How to improve the quality of corrugated board is a topic of common concern in the packaging industry. The following will explain how to improve the quality of corrugated board from the aspects of the adjustment of adhesives and gluing rollers, gluing amount, pressure and temperature

adhesive

the main raw material of adhesive is starch. The quality of starch has a direct impact on the quality of adhesive. If we choose the poor quality mainly from the innovative research and utilization progress of key battery materials, starch as raw material will make the viscosity and fluidity of the finished adhesive unstable, easy to precipitate, and the bonded paperboard has poor bonding strength, easy to deform, and it will be naturally opened if it is placed for a long time. Therefore, we must strictly control the quality when purchasing starch

at the same time, what are the standards for the advance and return difference of adhesive indication? The quality of paperboard is also directly affected by the manufacturing process. In order to theoretically reduce the production cost of adhesive, some enterprises will increase the proportion of water and starch in the production process, but in the production of paperboard, in order to achieve the bonding strength, they will blindly increase the amount of glue. We should know that starch is the main adhesive for paperboard, and water is only a link excipient. It is unscientific to reduce the production cost of adhesive by increasing the proportion of water and starch. This will not reduce the cost, but will have a serious impact on the quality of paperboard, so that the detection indicators can not meet the ideal requirements

the physical and chemical indexes of high-quality adhesives must be well controlled. Such as the ratio of starch to water, the viscosity, fluidity, pH value and gelatinization temperature of the finished adhesive. The changes of these indicators will have a great impact on the bonding strength and flatness of paperboard. Therefore, the following points must be paid attention to in the production process of adhesive:

a strict quality requirement for various raw and auxiliary materials:

■ the dosage of various raw and auxiliary materials should be changed according to the change of climate:

■ borax must be completely dissolved in hot water before it can be put in:

■ do not use river water or boiled water as water source:

■ the key point of high-quality adhesive is high concentration Low viscosity (that is, the proportion of water and starch should not be too different, but the fluidity must be good):

■ the finished adhesive should not have sediment:

■ the viscosity of the adhesive should not change too much during storage and use

■ it should have good permeability and initial viscosity in the production process

the qualified adhesive should be the rapid gelatinization and bonding of the two papers under the action of high temperature and pressure after gluing, and the peeling should be the tearing of the paper fiber, not the separation of the adhesive. In order to improve the quality of adhesives, additives with better applicability can be selected as excipients. Some additives can indeed reduce the gelatinization temperature and improve the bonding strength, and play a certain role in improving the quality of paperboard

adjustment of gluing roller and gluing amount in the whole production process of corrugated board, adhesive is an indispensable and important part. The amount of glue will not only bring changes to the production cost, but also have a direct impact on the quality of paperboard. Some operators worry that reducing the amount of gluing will cause poor adhesion to the table and blindly increase the amount of gluing. This method may improve the bonding fastness, but many undesirable quality defects are highlighted, such as the surface washboard, chicken skin, transparent, soft paperboard, poor strength, thin thickness and many other disadvantages, resulting in high cost and low quality

in order to control the gluing amount, the gluing device should first be accurately measured and adjusted. The gap between the gluing roller and the squeegee roller at the gluing part of the single-sided machine must be consistent at both ends, without any error, otherwise the amount of gluing will lead to the uneven moisture content of the paperboard and the deformation of both sides of the paperboard will be inconsistent. Although the single screw extruder has been relatively perfect in recent years, the paperboard will produce unilateral bending, causing trouble to the next process. The gap between the gluing roller and the corrugating roller must be consistent at both ends. In addition, the proper gap between the two rollers should be controlled. The gap is too large to cause poor gluing and local blistering and poor adhesion: because the linear speed of the corrugating roller and the gluing roller is inconsistent during operation. Too small gap will cause friction between the two rollers and damage the gluing roller, resulting in irreparable consequences and failure of normal production. Therefore, care must be taken when adjusting, and the expansion deformation of the corrugated roll after heating should be taken into account, so the adjustment must not be too hasty

the gap between the glue applicator roll inlet of 37.853 million tons and the squeegee roll at the double-layer glue applicator should also ensure that the two ends are consistent without any error. However, under normal circumstances, the gap between the gluing roller and the paper pressing roller should be reduced by about 0.30mm according to the thickness of the two layers of paperboard. Too much clearance will lead to poor gluing and waste products: too small clearance will make the corrugated paper contact the gluing roller too much and make the corrugated paper exceed the actual gluing amount when gluing. When the paperboard enters the drying channel for compounding, the corrugated will be flattened and inverted under the action of the gravity roll, making the paperboard thinner and softer. Therefore, we must be careful and strive for accuracy when adjusting the gap between the rollers of the gluing device. At the same time, we should strictly control the gluing amount, and the gluing area must be controlled within 1mm ~ 1.5mm width of the corrugated peak, otherwise it will not only increase the production cost, but also make the product quality unsatisfied

pressure

the whole production process of corrugated board is inseparable from pressure. Pressing corrugated requires pressure, and the bonding between paper and paper also requires the cooperation of pressure. Therefore, appropriate pressure is an important guarantee for manufacturing high-quality corrugated board

what kind of pressure is appropriate? In the production process of the single-sided machine, the pressure between the corrugating roll and the corrugating roll should be controlled between 0.3MPa and 0.4MPa under normal circumstances (the parallelism of the two rolls must be the same). Too small pressure will cause poor corrugation pressing, such as the corrugation tilting in the same direction or high and low corrugation and other quality problems: too much pressure will cause damage to the corrugated fiber and reduce the compressive strength of the corrugated board. Excessive pressure will also accelerate the wear of corrugating rollers, thereby reducing their service life

under normal circumstances, the pressure between the corrugating roller and the pressure roller should be controlled at about 0.4MPa, but it should be flexibly controlled according to the quality of the paper. The raw material of paper making with good grade is pure wood pulp or raw material with a high proportion of wood pulp, so the tightness is relatively tight, and the adhesive is difficult to penetrate into the fiber of the paper after gluing. Therefore, the pressure should be higher: the raw materials of low-grade paper are basically waste paper and recycled paper, and the physical indicators are poor. If the pressure is too high, the fiber of the paper will be damaged or even the paper will be crushed. In actual production, the pressure of the pressure roller should be properly adjusted and controlled according to the quality of the paper on the premise of ensuring the bonding strength

the adjustment of gravity roll pressure at the double-layer compound machine is generally ignored. At present, the allocation of tile line cadres in domestic carton factories is mostly designed according to the early production of high gram weight tile paper, while low gram weight tile paper is particularly demanding on the pressure of gravity rollers during production. The pressure must be appropriate. Otherwise, the quality of paperboard will not be satisfactory. When adjusting the pressure of the gravity roll, there must be "heavy and light". Generally, three gravity rolls can be set as a group. The pressure of the first gravity roll along the inlet of the drying channel is the heaviest, the second is the second, and the third is the lightest, and so on, but the pressure at both ends must be the same, otherwise it will cause uneven thickness on both sides of the paperboard. Only through continuous exploration and adjustment in actual production can we find the appropriate pressure for the production of low gram weight paperboard

temperature for the production of corrugated board production line, it is similar to the relationship between water and fish. The preheater, corrugating roller and hot plate all need a certain temperature guarantee in order to produce normally. Therefore, temperature is also one of the important factors affecting the quality of II direction paperboard. The temperature can not only change the moisture content of the paperboard, but also affect the bonding strength of the paperboard. Because the adhesive we currently use is raw starch glue, and raw glue cannot bond the object without the cooperation of temperature. Here, a gelatinization process is required. In this process, the temperature must reach more than 60 ℃, otherwise the raw glue cannot be gelatinized completely, and the adhesive without complete gelatinization cannot achieve the ideal bonding strength. Moreover, the bonding point of corrugated board is in the middle of two or more layers of paper. It is necessary to turn the raw rubber into mature glue and bond at the moment after gluing, so there must be a higher temperature on the working surface of corrugated roller, pressure roller and hot plate. Generally, the surface temperature of medium speed line production must reach more than 170 ℃, while high-speed line production requires higher surface temperature, otherwise the bonding point cannot reach more than 60 ℃ in an instant

because the base paper we use is provided by different suppliers, and the base paper is affected by air humidity during transportation and storage, the water content of the base paper varies, so it is an essential and important step to use preheater to regulate the water content of the base paper during production. When the moisture content of the base paper is high, the paper guide roller should be used to increase the contact area between the base paper and the preheater; On the contrary, the contact area between the two should be reduced. In short, when multi-layer paper is glued into cardboard, the water content of the paper should be as consistent as possible. To avoid bending of the cardboard

at the same time, we should often test the surface temperature of each roller and hot plate in production. When we find that the temperature of a certain part is abnormal and the steam pressure is normal, we need to check whether there is a problem in the drainage system. Because only by draining the condensed water in the high-pressure cavity as much as possible can the temperature meet the production requirements be provided

the production of corrugated board is a complex process. There are many factors involved in the production of high-quality corrugated board. It includes the adjustment of raw materials, adhesives, pressure, temperature, speed and equipment. Improving the quality of corrugated board also depends on the continuous learning and exploration of all employees in the actual production. These are inseparable from human control factors. Efficient and pragmatic managers, excellent technical talents and good teamwork spirit are also necessary conditions to improve product quality

sang Chunbao information source: Global corrugated industry