phenolic resin
DATE：2022/6/27 8:48:01 / READ： / SOURCE：This station
phenolic resin
Phenolic foam is an open cell thermosetting foam made of phenol and formaldehyde as main raw materials and mixed with foaming agent, surfactant, curing agent and other additives. It has the advantages of good flame retardancy, heat resistance, flame resistance and self extinguishing, low smoke during combustion and no dripping, so it is widely used as heat insulation materials. PVB film production line www.handern com
① Phenol and formaldehyde are prepared in the ratio of 1: (1.5~30), polycondensation reaction is carried out under alkaline conditions, neutralization is carried out when the predetermined requirements are met, and a grade a phenolic solution with a degree of 2.5 PA · s at 23 ℃ is prepared, which is the resin for producing foamed plastics.
② Linear phenolic resin and A-grade phenolic resin are the main raw materials for the production of phenolic foam. The foaming mechanism of linear resin is different from that of class a resin, and the selected foaming agent is different. Linear resin belongs to chemical foaming, and the foaming agent generates gas when it meets acid or decomposes when it meets heat. With the catalysis of acid catalyst, the resin releases heat and heats up, so that the gas expands and bubbles. Class a resin belongs to physical foaming. It is mixed with foaming agent in the resin and evenly dispersed in the whole system. It is also catalyzed by catalyst, and the temperature rises sharply, and the gas expands and foams. The most commonly used resin is grade a phenolic resin, especially phenolic foam for heat insulation, which accounts for about 60% of the total products. The resin is brown liquid at room temperature. Therefore, it is easy to fill the mold and fully mix with other components in the foaming process. PVB film production line www.handern com
③ According to product performance and production process requirements, phenolic resin mainly controls viscosity, moisture and free phenol content. The resin viscosity affects the foaming condition and the quality of foam. The viscosity is too high, the components are not easy to mix evenly during foaming, and the mold filling is difficult due to poor fluidity; When the viscosity is too low, the foaming agent is easy to escape and bubbles appear, which is not conducive to the formation of uniform and fine cell structure. The resin viscosity is usually 2~8pa · s. PVB film production line www.handern com
④ The content of water in the resin not only affects the viscosity of the resin, but also affects the quality of foam foam and foam products. Foreign countries attach great importance to the development of its varieties. No matter what kind of surfactant is selected, the effect of curing agent -- strong acid must be kept stable.
Foaming agent is an important component in the production of phenolic foam, and it is the material that makes the plastic produce microporous structure. According to the foaming mechanism, it can be divided into physical foaming agent and chemical foaming agent. PVB film production line www.handern com
① Physical blowing agents often use dichloromethane, petroleum ether, ethane, pentane, and CFC compounds. Because the physical foaming agent does not change chemically during the foaming process, it only generates a large amount of gas through the change of physical state, making the polymer foaming. The commonly used blowing agent is fluorocyanocarbon compound. To reduce the harm to the atmospheric ozone layer. Choose more HCFCs with less harm. At present, the amount of fluoride foaming agent is mostly reduced, and some substitutes are added, such as F-11 and pentane. Using low boiling point alkane as blowing agent, the effect and safety are not ideal because it is flammable and explosive. In order to improve the quality of foam, or reduce the dosage of HCFCs, or develop low hazard HCFCs. We should actively explore the high-efficiency and safe blowing agent of non CFCs.
② The chemical blowing agent mostly adopts decomposition blowing agent (sodium bicarbonate), water vapor generated by curing reaction, thermal decomposition blowing agent (AC blowing agent), etc.
The auxiliary agent can adjust the viscosity of the foam and has the plasticizing function to make the foam uniform and elastic and increase the strength. Commonly used additives include dioctyl phthalate, xylene phosphate, polyethylene glycol and ethylene glycol.
Fillers are used to improve the properties of foam, such as reducing brittleness and pulverization, improving rigidity, strength, compression resistance and flame retardancy. Appropriate amount of fillers such as glass fiber, kaolin and fly ash can be added according to the use of foam, which can not only improve the performance, but also reduce the cost.
Phenolic foam is an open cell thermosetting foam made of phenol and formaldehyde as main raw materials and mixed with foaming agent, surfactant, curing agent and other additives. It has the advantages of good flame retardancy, heat resistance, flame resistance and self extinguishing, low smoke during combustion and no dripping, so it is widely used as heat insulation materials. PVB film production line www.handern com
① Phenol and formaldehyde are prepared in the ratio of 1: (1.5~30), polycondensation reaction is carried out under alkaline conditions, neutralization is carried out when the predetermined requirements are met, and a grade a phenolic solution with a degree of 2.5 PA · s at 23 ℃ is prepared, which is the resin for producing foamed plastics.
② Linear phenolic resin and A-grade phenolic resin are the main raw materials for the production of phenolic foam. The foaming mechanism of linear resin is different from that of class a resin, and the selected foaming agent is different. Linear resin belongs to chemical foaming, and the foaming agent generates gas when it meets acid or decomposes when it meets heat. With the catalysis of acid catalyst, the resin releases heat and heats up, so that the gas expands and bubbles. Class a resin belongs to physical foaming. It is mixed with foaming agent in the resin and evenly dispersed in the whole system. It is also catalyzed by catalyst, and the temperature rises sharply, and the gas expands and foams. The most commonly used resin is grade a phenolic resin, especially phenolic foam for heat insulation, which accounts for about 60% of the total products. The resin is brown liquid at room temperature. Therefore, it is easy to fill the mold and fully mix with other components in the foaming process. PVB film production line www.handern com
③ According to product performance and production process requirements, phenolic resin mainly controls viscosity, moisture and free phenol content. The resin viscosity affects the foaming condition and the quality of foam. The viscosity is too high, the components are not easy to mix evenly during foaming, and the mold filling is difficult due to poor fluidity; When the viscosity is too low, the foaming agent is easy to escape and bubbles appear, which is not conducive to the formation of uniform and fine cell structure. The resin viscosity is usually 2~8pa · s. PVB film production line www.handern com
④ The content of water in the resin not only affects the viscosity of the resin, but also affects the quality of foam foam and foam products. Foreign countries attach great importance to the development of its varieties. No matter what kind of surfactant is selected, the effect of curing agent -- strong acid must be kept stable.
Foaming agent is an important component in the production of phenolic foam, and it is the material that makes the plastic produce microporous structure. According to the foaming mechanism, it can be divided into physical foaming agent and chemical foaming agent. PVB film production line www.handern com
① Physical blowing agents often use dichloromethane, petroleum ether, ethane, pentane, and CFC compounds. Because the physical foaming agent does not change chemically during the foaming process, it only generates a large amount of gas through the change of physical state, making the polymer foaming. The commonly used blowing agent is fluorocyanocarbon compound. To reduce the harm to the atmospheric ozone layer. Choose more HCFCs with less harm. At present, the amount of fluoride foaming agent is mostly reduced, and some substitutes are added, such as F-11 and pentane. Using low boiling point alkane as blowing agent, the effect and safety are not ideal because it is flammable and explosive. In order to improve the quality of foam, or reduce the dosage of HCFCs, or develop low hazard HCFCs. We should actively explore the high-efficiency and safe blowing agent of non CFCs.
② The chemical blowing agent mostly adopts decomposition blowing agent (sodium bicarbonate), water vapor generated by curing reaction, thermal decomposition blowing agent (AC blowing agent), etc.
The auxiliary agent can adjust the viscosity of the foam and has the plasticizing function to make the foam uniform and elastic and increase the strength. Commonly used additives include dioctyl phthalate, xylene phosphate, polyethylene glycol and ethylene glycol.
Fillers are used to improve the properties of foam, such as reducing brittleness and pulverization, improving rigidity, strength, compression resistance and flame retardancy. Appropriate amount of fillers such as glass fiber, kaolin and fly ash can be added according to the use of foam, which can not only improve the performance, but also reduce the cost.
Author：admin