Qin Zhaoxing (Guilin Huade Wood Industry Machinery Co., Ltd., Guilin 541004, China)
In recent years, with the vigorous development of China's wood-based panel industry, the production scale of wood-based panel enterprises has continued to expand, and the demand for adhesives for wood-based panels has also increased. Adhesives, which play an important role in the production of wood-based panels, often determine wood-based panels. The quality and grade of the product also play a pivotal role in the cost of the product. The quality of adhesives and production costs have become an important factor that directly affects the market competitiveness of human-board products and the profits of manufacturers. In order to ensure the normal production and quality of products, most of China's wood-based panel enterprises have their own adhesive production workshops, and they are all intermittent production. How to reduce the unstable factors in resin production and produce the required adhesives to ensure the quality of wood-based panel products and reduce production costs has been valued by more and more enterprises. The following is a brief analysis of the causes of the reaction wall sticking phenomenon in the resin production, and the measures to reduce the sticking wall are proposed for reference.
1 process factor
1.1 Reaction temperature and time
When the temperature of the reaction solution is lower than 80 °C, if ammonia chloride is used as the catalyst, the reaction value of the ammonia chloride is fast, the pH value does not show up, and after the temperature rises, the pH value decreases rapidly, the reaction speed increases, and the polycondensation reaction is too high. Intensely causing gelation and sticking to the wall. In addition, the polycondensation reaction time is too long, the molecular weight of the resin is large, and the viscosity is too high, and the sticking phenomenon is likely to occur. Therefore, the temperature and time of the polycondensation reaction should be properly controlled during the operation, and the reaction should be terminated in time. Generally, the temperature of the reaction solution should be controlled within ~95 °C.
1.2 Wall temperature difference
If the temperature of the cooling medium is too low or suddenly drops, the temperature difference between the temperature of the kettle wall and the material is too large, causing the glue contacting the wall of the kettle to stick to the wall. Therefore, both heating and cooling should be carried out within a reasonable temperature difference. Generally, the steam use temperature should be less than 180 °C, the thermal shock should be less than 120 °C, and the cooling shock should be less than 90 °C. At the same time, care should be taken to determine the proper inlet and outlet temperatures of the cooling medium and to maintain a balanced operation.
1.3 The degree of balance of operation
When the control parameters such as temperature and pressure are unstable or the fluctuation is too large, the process of resin polycondensation is uneven, and it is easy to cause sticking. Therefore, in the production operation, it should be slowly pressurized and heated. Generally, water vapor of about 0.15 MPa is passed for 2 to 3 minutes, and then the pressure is gradually raised. The lifting speed is preferably 0.1 to 0.15 MPa per minute.
1.4 Raw material factors
Because the sulfate content in urea is too high, when urea is added in the late stage of the polycondensation reaction of the resin, it is equivalent to adding a curing agent to promote the rapid crosslinking of the resin into a network structure. If the treatment is not timely, the resin will be solidified in the reaction. In the kettle, therefore, standard industrial urea raw materials should be used in the production to limit the sulfate content in urea to 0.01% or less.
2 equipment factors
2.1 Flow characteristics
The flow state of the material in the reactor also affects the degree of sticking, and improving the flow effect of the material can greatly reduce the degree of sticking. The new turbine agitation method we use in the design allows the material to flow radially, which improves the degree of sticking.
2.2 Inner wall treatment
The rough inner wall is easy to hang glue. Therefore, in the process of processing, the inner wall of the reactor, the heat exchanger and the weld bead are polished and polished to improve the smoothness of the kettle and reduce the sticking wall. In addition, through technical improvements, the solder joints in the reactor are reduced, and the phenomenon of hanging glue can be reduced to some extent.
2.3 Eliminate dead ends
Due to the unreasonable structure of the device, it is easy to stick to the wall where the dead angle is excessive. Therefore, we try to eliminate the dead angle of the equipment structure in the design. In the new heat exchanger, the heat exchange area is large, the material flow is good, and the sticky wall is reduced (for details, see <<Technical Features and Improvements of Large Capacity Reactor>).
2.4 Feed pipe position
The feeding tube is a dead angle that is difficult to stir. Because of the large local concentration of the nozzle, it is easy to cause sticking. Therefore, the position of the feeding tube should be reasonably determined. We use the side pipe on the nozzle design to make the material slowly fall to the reaction liquid surface at a certain angle, to avoid the glue splashing to the inner wall surface of the kettle, and to stir at a constant speed to make the material distribution as uniform as possible, thereby reducing the glue.
In addition, when the inner wall of the kettle is glued, the high-pressure water spray device can be used for wall cleaning.
Since the synthetic resin used in the wood industry has a certain viscosity, the problem of sticking walls will inevitably occur in the rubber making process. If the technical treatment is not carried out in time, the heat transfer coefficient of the reactor will be affected and the energy consumption of the rubber can be increased. . In addition, the sticking phenomenon of the reaction kettle caused by the gel phenomenon is mostly caused by the process. If the technical parameters are not found and adjusted in time, the quality of the glue may be directly affected. By adopting the above technical measures, it is possible to greatly reduce the sticking wall and ensure efficient operation of the rubber production.
Most of the facial wrinkles are caused by facial muscles. Using botulinum toxin (Botulax and Meditoxin) injections to reduce the formation of wrinkles and facial muscles. The facial wrinkles are flattened. It has good effect to remove brow wrinkles, forehead wrinkles, eyelids, mouth wrinkles and nose bridge wrinkles.
*Modify face type
The square face can be treated by the principle of paralyzing muscles, muscle atrophy and muscle volume becoming smaller. The effect of muscle atrophy to correct the square face can last for about 1 year.
* Skinny legs
Inject botulinum toxin into the calf, paralyze some of the calf muscle tissue, induce muscle atrophy and slim the thick calf, showing a soft curve.
In recent years, with the vigorous development of China's wood-based panel industry, the production scale of wood-based panel enterprises has continued to expand, and the demand for adhesives for wood-based panels has also increased. Adhesives, which play an important role in the production of wood-based panels, often determine wood-based panels. The quality and grade of the product also play a pivotal role in the cost of the product. The quality of adhesives and production costs have become an important factor that directly affects the market competitiveness of human-board products and the profits of manufacturers. In order to ensure the normal production and quality of products, most of China's wood-based panel enterprises have their own adhesive production workshops, and they are all intermittent production. How to reduce the unstable factors in resin production and produce the required adhesives to ensure the quality of wood-based panel products and reduce production costs has been valued by more and more enterprises. The following is a brief analysis of the causes of the reaction wall sticking phenomenon in the resin production, and the measures to reduce the sticking wall are proposed for reference.
1 process factor
1.1 Reaction temperature and time
When the temperature of the reaction solution is lower than 80 °C, if ammonia chloride is used as the catalyst, the reaction value of the ammonia chloride is fast, the pH value does not show up, and after the temperature rises, the pH value decreases rapidly, the reaction speed increases, and the polycondensation reaction is too high. Intensely causing gelation and sticking to the wall. In addition, the polycondensation reaction time is too long, the molecular weight of the resin is large, and the viscosity is too high, and the sticking phenomenon is likely to occur. Therefore, the temperature and time of the polycondensation reaction should be properly controlled during the operation, and the reaction should be terminated in time. Generally, the temperature of the reaction solution should be controlled within ~95 °C.
1.2 Wall temperature difference
If the temperature of the cooling medium is too low or suddenly drops, the temperature difference between the temperature of the kettle wall and the material is too large, causing the glue contacting the wall of the kettle to stick to the wall. Therefore, both heating and cooling should be carried out within a reasonable temperature difference. Generally, the steam use temperature should be less than 180 °C, the thermal shock should be less than 120 °C, and the cooling shock should be less than 90 °C. At the same time, care should be taken to determine the proper inlet and outlet temperatures of the cooling medium and to maintain a balanced operation.
1.3 The degree of balance of operation
When the control parameters such as temperature and pressure are unstable or the fluctuation is too large, the process of resin polycondensation is uneven, and it is easy to cause sticking. Therefore, in the production operation, it should be slowly pressurized and heated. Generally, water vapor of about 0.15 MPa is passed for 2 to 3 minutes, and then the pressure is gradually raised. The lifting speed is preferably 0.1 to 0.15 MPa per minute.
1.4 Raw material factors
Because the sulfate content in urea is too high, when urea is added in the late stage of the polycondensation reaction of the resin, it is equivalent to adding a curing agent to promote the rapid crosslinking of the resin into a network structure. If the treatment is not timely, the resin will be solidified in the reaction. In the kettle, therefore, standard industrial urea raw materials should be used in the production to limit the sulfate content in urea to 0.01% or less.
2 equipment factors
2.1 Flow characteristics
The flow state of the material in the reactor also affects the degree of sticking, and improving the flow effect of the material can greatly reduce the degree of sticking. The new turbine agitation method we use in the design allows the material to flow radially, which improves the degree of sticking.
2.2 Inner wall treatment
The rough inner wall is easy to hang glue. Therefore, in the process of processing, the inner wall of the reactor, the heat exchanger and the weld bead are polished and polished to improve the smoothness of the kettle and reduce the sticking wall. In addition, through technical improvements, the solder joints in the reactor are reduced, and the phenomenon of hanging glue can be reduced to some extent.
2.3 Eliminate dead ends
Due to the unreasonable structure of the device, it is easy to stick to the wall where the dead angle is excessive. Therefore, we try to eliminate the dead angle of the equipment structure in the design. In the new heat exchanger, the heat exchange area is large, the material flow is good, and the sticky wall is reduced (for details, see <<Technical Features and Improvements of Large Capacity Reactor>).
2.4 Feed pipe position
The feeding tube is a dead angle that is difficult to stir. Because of the large local concentration of the nozzle, it is easy to cause sticking. Therefore, the position of the feeding tube should be reasonably determined. We use the side pipe on the nozzle design to make the material slowly fall to the reaction liquid surface at a certain angle, to avoid the glue splashing to the inner wall surface of the kettle, and to stir at a constant speed to make the material distribution as uniform as possible, thereby reducing the glue.
In addition, when the inner wall of the kettle is glued, the high-pressure water spray device can be used for wall cleaning.
Since the synthetic resin used in the wood industry has a certain viscosity, the problem of sticking walls will inevitably occur in the rubber making process. If the technical treatment is not carried out in time, the heat transfer coefficient of the reactor will be affected and the energy consumption of the rubber can be increased. . In addition, the sticking phenomenon of the reaction kettle caused by the gel phenomenon is mostly caused by the process. If the technical parameters are not found and adjusted in time, the quality of the glue may be directly affected. By adopting the above technical measures, it is possible to greatly reduce the sticking wall and ensure efficient operation of the rubber production.
Botulnum Toxin Treatment
* Remove wrinklesMost of the facial wrinkles are caused by facial muscles. Using botulinum toxin (Botulax and Meditoxin) injections to reduce the formation of wrinkles and facial muscles. The facial wrinkles are flattened. It has good effect to remove brow wrinkles, forehead wrinkles, eyelids, mouth wrinkles and nose bridge wrinkles.
*Modify face type
The square face can be treated by the principle of paralyzing muscles, muscle atrophy and muscle volume becoming smaller. The effect of muscle atrophy to correct the square face can last for about 1 year.
* Skinny legs
Inject botulinum toxin into the calf, paralyze some of the calf muscle tissue, induce muscle atrophy and slim the thick calf, showing a soft curve.
Botulax and Meditoxin
Dermax Technology Limited , https://www.dermaxmed.com