News Details
Polypropylene antioxidants
2017-12-28 15:38:12
Polypropylene antioxidants
Polypropylene under anaerobic conditions with good stability, but because there are a tertiary carbon atoms, polypropylene structure in the process of granulation processing, storage and use, the effect of heat, oxygen, light aging degradation, or even the loss of good comprehensive physical and mechanical properties and use value, which is poor than polyethylene polypropylene oxidation resistance and aging resistance.
In order to prevent and delay the oxidation degradation of polypropylene, the molecular weight of polypropylene unchanged, usually after polymerization reaction, separation, drying and storage before adding polypropylene antioxidant treatment is a must, in the stage of granulation join polypropylene antioxidant, is to increase the oxygen resistance of polypropylene is simple and effective way.
The mechanism of polypropylene antioxidant. Chain initiation. Polypropylene (RH) can easily generate free radicals in its tertiary carbon atom under the action of oxygen, light or heat.
RH light and heat R+H
RH + O2 R + HOO
Chain transfer. Free radicals automatically generate hydrogen peroxide free radicals and macromolecular peroxide, peroxide decompose and produce free radicals, free radicals and polymer reaction, free radicals to transfer, reaction:
R + O2ROO
ROO + RHROOH + R
ROOHRO + HO
RH ROOH + RO + R + H2O
RO + RHROH + R
HO + RHH2O + R
2 roohro + + H2O ROO
Chain termination. Free radicals combine to produce stable products and terminate chain reaction:
R + RR - R
R + ROOROOR
ROO + ROOROOR + O2
ROO + ROROR + O2
R + OH ROH
Triphenyl phosphite (antioxidant, stabilizer TPPi) production process
1. Phosphorus oxychloride as the direct method (also called thermal method) phenol with pyridine and anhydrous benzene as solvent, in no more than 10 ℃ temperature, slowly add oxygen phosphorus chloride, then under reflux temperature, the reaction of 3 ~ 4 h. After cooling to room temperature, the reactants are washed by water to recycle pyridine. After centrifugal dehydration, the reagents are dehydrated with dried sodium sulfate, which is filtered to remove sodium sulfate. The first atmospheric distillation recovery of benzene, vacuum distillation, collected 243 ~ 245 ℃ (1.47 kPa) fraction, by cooling, crystallization, crushing is the finished product.
2. After phenol melting, stirring under add phosphorus trichloride under 25 ℃, Triphenyl phosphite is generated; Then heat up to 70 ℃ ventilation with chlorine gas, generated two chlorinated triphenyl phosphate; Again at 50 ℃ water hydrolysis, triphenyl phosphate. The hydrolysate with 5% soda solution for neutralization, water washing, the evaporation and vacuum distillation, collected 243 ~ 245 ℃ (1.47 kPa) fractions, cooling, crystallization, crushing, packaging is the finished product.
Triphenyl phosphite (TPPi antioxidants, stabilizer) is mainly used in PVC, polyethylene, polypropylene, polystyrene, polyester, abs resin, epoxy resin, synthetic rubber antioxidant stabilizer, used in polyvinyl chloride (PVC) products as a chelating agent.
In the process of oxidation, the molecular weight decreases, the melt viscosity decreases, and the strength of polypropylene decreases or pulverized when the major chain breaks down. When the macromolecules cross the crosslinking reaction, the molecular weight increases, the melt flow decreases, and the brittleness and hardening occur. Generated in the process of oxidation of the oxide structure, such as carbonyl, peroxide, reduces the electric properties of polypropylene, and increases the light degradation caused by the sensitivity of the oxidation further response of the structure, make the fracture or macromolecular crosslinking.
Antioxidant role is to prevent the polypropylene autooxidation chain reaction process, namely the supply of hydrogen generated in the oxidation process of free radical R and ROO into RH and ROOH, or make ROOH ROH, thus improving polypropylene in the processing and application of antioxidant and ability to resist pyrolysis.
Polypropylene is a thermoplastic resin produced by polymerization of propylene. There are three types of polypropylene, atactic polypropylene, and syndiotactic polypropylene.
The same side of the methyl groups are arranged in the main chain of the molecule called isotactic polypropylene, if methyl chaotic are arranged at both sides of the main chain molecules called atactic polypropylene, when both sides of the methyl arranged alternately in the main chain of the molecule called syndiotactic polypropylene. In the polypropylene resin of general industrial production, the content of the isotactic structure is about 95%, and the rest is the non-regulation or the polypropylene. Industrial products are the main components of such commodities. Polypropylene also includes copolymer with propylene and a small amount of ethylene. Usually translucent and colorless solid, odorless and non-toxic. Because of its neat and high crystallization structure, so the melting point can be as high as 167 ℃. Heat resistance, corrosion resistance, the use of steam sterilization is its outstanding advantages. Small density, the lightest general purpose plastic. The disadvantage is that the low temperature resistance impact is poor and it is easy to age, but can be overcome by modification.
Copolymer of PP material with low thermal deformation temperature (100 ℃), low transparency and gloss, low rigidity, but have stronger impact strength, impact strength of PP increased with the increase of ethylene content increased. PP vicat softening temperature is 150 ℃. Due to the high degree of crystallinity, the surface stiffness and anti-scratch characteristics of this material are very good. There is no environmental stress cracking problem.
The melt mass flow rate (MFR) of PP is usually 1~ 100. PP materials with low MFR have good anti-impact properties but low tensile strength. For the same MFR materials, the copolymerization type of anti-impact strength is higher than the homotype. Because of crystallization, the shrinkage rate of PP is quite high, generally 1.6~ 2.0%.
Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd
http://www.yaruichem.com
Polypropylene under anaerobic conditions with good stability, but because there are a tertiary carbon atoms, polypropylene structure in the process of granulation processing, storage and use, the effect of heat, oxygen, light aging degradation, or even the loss of good comprehensive physical and mechanical properties and use value, which is poor than polyethylene polypropylene oxidation resistance and aging resistance.
In order to prevent and delay the oxidation degradation of polypropylene, the molecular weight of polypropylene unchanged, usually after polymerization reaction, separation, drying and storage before adding polypropylene antioxidant treatment is a must, in the stage of granulation join polypropylene antioxidant, is to increase the oxygen resistance of polypropylene is simple and effective way.
The mechanism of polypropylene antioxidant. Chain initiation. Polypropylene (RH) can easily generate free radicals in its tertiary carbon atom under the action of oxygen, light or heat.
RH light and heat R+H
RH + O2 R + HOO
Chain transfer. Free radicals automatically generate hydrogen peroxide free radicals and macromolecular peroxide, peroxide decompose and produce free radicals, free radicals and polymer reaction, free radicals to transfer, reaction:
R + O2ROO
ROO + RHROOH + R
ROOHRO + HO
RH ROOH + RO + R + H2O
RO + RHROH + R
HO + RHH2O + R
2 roohro + + H2O ROO
Chain termination. Free radicals combine to produce stable products and terminate chain reaction:
R + RR - R
R + ROOROOR
ROO + ROOROOR + O2
ROO + ROROR + O2
R + OH ROH
Triphenyl phosphite (antioxidant, stabilizer TPPi) production process
1. Phosphorus oxychloride as the direct method (also called thermal method) phenol with pyridine and anhydrous benzene as solvent, in no more than 10 ℃ temperature, slowly add oxygen phosphorus chloride, then under reflux temperature, the reaction of 3 ~ 4 h. After cooling to room temperature, the reactants are washed by water to recycle pyridine. After centrifugal dehydration, the reagents are dehydrated with dried sodium sulfate, which is filtered to remove sodium sulfate. The first atmospheric distillation recovery of benzene, vacuum distillation, collected 243 ~ 245 ℃ (1.47 kPa) fraction, by cooling, crystallization, crushing is the finished product.
2. After phenol melting, stirring under add phosphorus trichloride under 25 ℃, Triphenyl phosphite is generated; Then heat up to 70 ℃ ventilation with chlorine gas, generated two chlorinated triphenyl phosphate; Again at 50 ℃ water hydrolysis, triphenyl phosphate. The hydrolysate with 5% soda solution for neutralization, water washing, the evaporation and vacuum distillation, collected 243 ~ 245 ℃ (1.47 kPa) fractions, cooling, crystallization, crushing, packaging is the finished product.
Triphenyl phosphite (TPPi antioxidants, stabilizer) is mainly used in PVC, polyethylene, polypropylene, polystyrene, polyester, abs resin, epoxy resin, synthetic rubber antioxidant stabilizer, used in polyvinyl chloride (PVC) products as a chelating agent.
In the process of oxidation, the molecular weight decreases, the melt viscosity decreases, and the strength of polypropylene decreases or pulverized when the major chain breaks down. When the macromolecules cross the crosslinking reaction, the molecular weight increases, the melt flow decreases, and the brittleness and hardening occur. Generated in the process of oxidation of the oxide structure, such as carbonyl, peroxide, reduces the electric properties of polypropylene, and increases the light degradation caused by the sensitivity of the oxidation further response of the structure, make the fracture or macromolecular crosslinking.
Antioxidant role is to prevent the polypropylene autooxidation chain reaction process, namely the supply of hydrogen generated in the oxidation process of free radical R and ROO into RH and ROOH, or make ROOH ROH, thus improving polypropylene in the processing and application of antioxidant and ability to resist pyrolysis.
Polypropylene is a thermoplastic resin produced by polymerization of propylene. There are three types of polypropylene, atactic polypropylene, and syndiotactic polypropylene.
The same side of the methyl groups are arranged in the main chain of the molecule called isotactic polypropylene, if methyl chaotic are arranged at both sides of the main chain molecules called atactic polypropylene, when both sides of the methyl arranged alternately in the main chain of the molecule called syndiotactic polypropylene. In the polypropylene resin of general industrial production, the content of the isotactic structure is about 95%, and the rest is the non-regulation or the polypropylene. Industrial products are the main components of such commodities. Polypropylene also includes copolymer with propylene and a small amount of ethylene. Usually translucent and colorless solid, odorless and non-toxic. Because of its neat and high crystallization structure, so the melting point can be as high as 167 ℃. Heat resistance, corrosion resistance, the use of steam sterilization is its outstanding advantages. Small density, the lightest general purpose plastic. The disadvantage is that the low temperature resistance impact is poor and it is easy to age, but can be overcome by modification.
Copolymer of PP material with low thermal deformation temperature (100 ℃), low transparency and gloss, low rigidity, but have stronger impact strength, impact strength of PP increased with the increase of ethylene content increased. PP vicat softening temperature is 150 ℃. Due to the high degree of crystallinity, the surface stiffness and anti-scratch characteristics of this material are very good. There is no environmental stress cracking problem.
The melt mass flow rate (MFR) of PP is usually 1~ 100. PP materials with low MFR have good anti-impact properties but low tensile strength. For the same MFR materials, the copolymerization type of anti-impact strength is higher than the homotype. Because of crystallization, the shrinkage rate of PP is quite high, generally 1.6~ 2.0%.
Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd
http://www.yaruichem.com
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