The hottest paper mold enterprises must pay attent

Paper mold enterprises must pay attention to the quality of production water

recently, a manufacturer of chemical additives asked me a question: their products should be used in paper mold enterprises in the South because if the change-over switch works well, while in the north, the application effect of the same products is not ideal. Another auxiliary manufacturer asked me: their products are obviously different from similar products produced by different manufacturers. Other product manufacturers found that the scaling of molds was very serious, and they did not know the reason. The reason is that the water quality varies from place to place. They treated the production water, and these problems were solved

nature of natural water. Natural water contains various salts, which are dissolved in water to form ionic substances, namely cations (such as calcium, magnesium, silicon, iron ions, etc.) and anions (such as chloride ions, bicarbonate, sulfate, etc.). Some metal cations in the water are combined with some anions. During the heating process of the water, due to evaporation and concentration, precipitation occurs, forming substances insoluble in water, and adhering to the heating surface to form scale, which affects the heat conduction. We call the total concentration of these metal ions in water the hardness of water. The most common metal ions in natural water are calcium ions (Ca2 +) and magnesium ions (Mg2 +). Therefore, the total concentration of Ca2 + and Mg2 + is usually regarded as the hardness of water. Natural water is classified as follows according to hardness and salt content

hazards of hard water. Under certain conditions, Ca2 + and Mg2 + in hard water often scale on the surface of heating equipment. For example, pipe circulating water can scale the inner wall of the pipe. After the boiler is heated, the inner wall of the boiler scales. The cause of scaling of paper tableware forming hot pressing die is also greatly related to hard water. These scales not only affect the heat transfer effect, but also affect the normal operation of equipment in industrial production. The influence of hard water on some chemical additives may reduce the

efficiency of chemical additives, or make the precipitation of chemical additives ineffective. Therefore, if necessary, the water should be softened or demineralized according to the requirements of the equipment for water quality

due to the different requirements of equipment for water quality, water can be treated from one production line, and the treatment methods are also different

① electronic and electrostatic water treatment. Electronic and electrostatic water treatment technology is one of the latest technologies in the field of water industry in the world. It has been widely used in economically developed countries since the 1980s. Up to now, the application of this technology has extended from the fields of cooling circulation, heating and hot water supply to swimming pool water disinfection, prevention of secondary pollution of water tank water,

anti scaling and anti-corrosion of tap water pipelines

the principle of electrostatic water processor is that after the power is connected, the controller will supply energy to the energy discharger to form a high-voltage electrostatic field between the cathode and anode. When the treated water passes through the energy release device, the dipole moment of water molecules increases and is arranged in a chain according to the positive and negative orientation under the action of the field; At the same time, some physical properties of water change (conductivity, dissolved oxygen, adhesion force, surface tension, etc.). Generally, the water treated by this method is called electrostatic activated water

the anti scaling mechanism of electrostatic water treatment is that the anions and anions in water are more closely surrounded by water molecules with increased dipole moment and arranged in chains, which cannot move freely and close to the wall, thus preventing the formation of scale molecules on the wall

the mechanism of descaling in electrostatic water treatment is to increase the dipole moment of water molecules, which is easier to hydrate with the scale molecules on the wall, making the hard scale soft, loose, cracked and fallen off, until the scale is gradually removed

the mechanism of sterilization and corrosion inhibition is to increase the dipole moment of water molecules, form a water film on the metal wall, slow down oxidation corrosion, inactivate microorganisms, and eliminate biological corrosion, so as to eliminate the hazards of yellow water and rust to a certain extent

experience has proved that the water treated by electronic and electrostatic methods can be used as circulating water for pulp molding equipment pipes and cooling water for vacuum equipment, but the effect of reducing scaling for hot pressing molds is not good, because the mechanism of electrostatic water treatment can not eliminate calcium and magnesium ions in water, but can only make these ions not close to the pipe wall

② softening hard water can destroy the crystallization of CaCO3 and other salts by using scale inhibitors

③ the most effective method for pulp molding equipment is to use a water softener for water quality treatment. The function mechanism of water softener is ion exchange through softener resin. The ion exchange softening process of water involves hard minerals, mainly calcium and magnesium, which are replaced by sodium mineral exchange and common sheet metal damage. In addition to the above situation, they are also replaced in the process of transportation. Calcium and magnesium ions in water are actually ores dissolved in water. When water seeps into the rock and soil, it dissolves calcium and magnesium deposits and eventually enters the groundwater layer. When water is pumped from the underground water layer to the surface, the water contains calcium magnesium ion hard minerals, which is called hard water. The softener exchanges the calcium magnesium ion hard mineral dissolved in water with the soft mineral sodium on the softener resin. Sodium does little harm to the target object in contact with it, mainly because it does not accumulate on its surface in the form of scale. In a suitable container, water containing hard minerals can undergo ion exchange reaction through artificial ion exchange resin. When calcium and magnesium ions are replaced (exchanged), the positive sodium ions are connected to the negative exchange position, and the final exchange position is occupied by sodium ions. At this time, the water sent by the water softener is softened water

diluting chemical additives with softened water can not only reduce the amount of additives, but also maximize the effectiveness of chemical additives, so as to reduce the scaling of hot pressing dies and reduce the cost of additives. The author recently helped a pulp molding enterprise that has been troubled by hard water to install a water softening device, and the effect was very obvious. The amount of waterproof agent was reduced from 6% to 4.5%

a simple conductivity measuring pen can be used for the detection of water quality

methods to prevent mold scaling: Although the use of water treatment technology can reduce equipment scaling and increase the efficiency of chemical additives, the scaling problem of equipment cannot be completely solved due to the influence of slurry fine fibers and chemical additives. Due to different water quality in different regions of various manufacturers, the impact on molding equipment is also different, some scaling is fast, and some scaling is slow. No matter how fast or slow the scaling is, all enterprises must clean the molds regularly according to their own conditions, and do not clean them until the mold plug is seriously blocked, so as not to affect the service life of the mold and the normal production. A manufacturer in Jiangsu cleans the scale once a month, while a manufacturer in Shandong cleans it once a week. This is the effective temperature range of many drugs. After they installed the water softener, the situation improved significantly

three methods of chemical scale removal are introduced below:

1. Japan uses sodium hydroxide solution with a temperature above 80 ℃ and a concentration of 9% for cyclic cleaning. Under alkaline conditions, AQ scale can be completely removed by reducing and dissolving with a solution containing sodium dithionite

2. the method introduced in the U.S. patent is: using 0.5% hot base such as sodium carbonate sodium hydroxide solution and reducing reagents such as dithionite (sodium, zinc), sodium borohydride... And surfactants to clean AQ scale at 50 ~ 100 ℃, which has been proved to be a very effective and simple method

3. Some domestic manufacturers use 2 ~ 3% oxalic acid solution to add corrosion inhibitor to clean the mold with excellent effect. The method is to make a corrosion-resistant plastic tank, fill it with oxalic acid solution, put the scaled mold in, and then heat it to 45 ℃, soak it naturally or circularly for 4 hours, or use ultrasonic wave to vibrate the solution, so that the scale on the mold surface and in the eyelet can fall off by itself, and then wash it with clean water and dry it