Organic isocyanate is an important compound, which is widely used in polyurethane industry, coating industry, dyes and pesticides and other polymer materials.
rhi 3·3H2O 170 2 62.9 100
Taking the preparation of MDI as an example, the first step is to synthesize DPU (diphenyl urea):
The reaction was catalyzed by diethyl palladium. When aniline was excessive, DPU could obtain higher yield. Under the conditions of120 c, 4 1× 103kPa, the yield of DPU can reach over 90% after 4 hours of reaction.
The second step is the decomposition of DPU by methanol.
The reaction can be carried out without a catalyst. The third step is the thermal decomposition of carbamate, which is similar to the above reaction.
The method has wide sources of raw materials, mild reaction conditions, clear route and few side reactions. However, due to the use of diphenyl urea as an intermediate product, the application scope of this method is limited and it cannot be applied to diisocyanate with complex structure such as TDI.
South Korea's LG Company completed the synthesis of MDI with formaldehyde as an intermediate. The specific reaction route is as follows:
2
The reaction uses solid acid as catalyst, and the reaction product is benzyl carbamate, which can be decomposed into MDI by heating. The production cost of this method is slightly higher than that of phosgene method.
In a word, among various methods for synthesizing isocyanate by non-phosgene method, the simpler the steps, the more complicated the reaction itself and the more difficult it is to realize. Increasing the reaction route and gradually completing the reaction can greatly improve the feasibility of realizing the reaction. DMC method can be applied to the synthesis of various isocyanates with clear process route, few by-products and mild reaction conditions. Secondly, the methanol produced in the three-step reaction can be recovered and used to produce MDC. Although the production cost is slightly higher than that of phosgene method, it is environmentally friendly and has a good industrial prospect. Moreover, China already has the technology of dimethyl carbonate, and it is expected to realize the environmental protection synthesis of some isocyanate products in the near future, and at the same time develop the production routes of different isocyanate products.
Characteristics of Toluene Diisocyanate (TDI) and Its Harm to Human Body
Toluene diisocyanate (TDI) has two isomers: 2,4-toluene diisocyanate and 2,6-toluene diisocyanate. Toluene diisocyanate (TDI) is a water-white or light yellow liquid with a strong pungent smell, which accumulates and lurks in human body and has a strong irritating effect on skin, eyes and respiratory tract. Inhalation of high concentration toluene diisocyanate vapor can cause bronchitis, bronchopneumonia and pulmonary edema. Liquid contact with skin can cause dermatitis. Liquid contact with eyes can cause serious irritation, which may lead to permanent damage if it is not treated in time. Long-term exposure to toluene diisocyanate can cause chronic bronchitis. People who are allergic to toluene diisocyanate may cause asthma, wheezing, dyspnea and cough.
MDI is a mixture of diphenylmethane diisocyanate (pure MDI), pure MDI and polyphenyl polymethylene polyisocyanate (polymeric MDI) in a certain proportion, and the general name of modified products of pure MDI and polymeric MDI. It is the most important raw material for producing polyurethane, and a small amount of MDI is used in other aspects besides polyurethane. Polyurethane has both the elasticity of rubber and the strength and excellent processability of plastic, especially in heat insulation, sound insulation, wear resistance, oil resistance and elasticity. It is the sixth largest plastic after polyethylene, polyvinyl chloride, polypropylene, polystyrene and ABS, and is widely used in national defense, aerospace, light industry, chemical industry, petroleum, textile, transportation, automobile, medical treatment and other fields.
MDI and TDI are substitutes for each other, and they are both raw materials for producing polyurethane. At present, MDI is a little expensive, but its toxicity is lower than TDI, and the polyurethane products formed by MDI have relatively good moldability.
Polypropylene glycol PPG series
Appearance: colorless to yellowish oil.
Performance and application
1 and PPG series are soluble in organic solvents such as toluene, ethanol, trichloroethylene, etc., and PPG400 and PPG600 are soluble in water, which have lubrication, solubilization, defoaming and antistatic properties.
2. In cosmetics, PPG400 is used as emollient, softener and lubricant.
3. Used as an intermediate for esterification, etherification and polycondensation.
Brief introduction of polymer polyol (POP)
Usage and instructions:
POP93/28 is a polymer polyol with high activity and medium solid content, which is widely used, mainly for high resilience foam, hot film plastic soft foam, semi-rigid foam, self-skinning foam, reaction injection molding (RIM) products and so on.
Second, the implementation standards:
Enterprise standard
Third, technical indicators.
1 appearance
Milky white liquid
2, physical and chemical performance indicators
Indicator name indicator
Hydroxyl value mgKOH/g 23~27 ~ 27
Viscosity MPa s/25℃ ≤ 3500
Moisture% ≤0.05
The PH value is 6-9
Solid content% 27 1
Residual monomer ppm ≤ 100
POP36/2
I. Purpose and description:
POP36/28 is a substitute product of POP3 1/28. It is a polymer polyol with high activity and low solid content. Widely used, mainly used in high resilience foam, hot film plastic soft foam, semi-rigid foam, self-skinning foam, reaction injection molding (RIM) products, etc.
Second, the implementation standards:
Enterprise standard
Third, technical indicators.
1 appearance
Pale yellow liquid
2, physical and chemical performance indicators
Indicator name indicator
Hydroxyl value mgKOH/g 25~29 ~ 29
Viscosity MPa s/25℃ ≤ 3500
Moisture% ≤0.05
The PH value is 6-9
Solid content% 23 1
Residual monomer ppm ≤ 100
Pop -43
I. Purpose and description:
POP-43 is a polymer polyol with high solid content, which is widely used, mainly used in high resilience foam, thermoformed soft foam, high hardness block foam products and so on.
Second, the implementation standards:
Enterprise standard
Third, technical indicators.
1 appearance
Milky white liquid
2, physical and chemical performance indicators
Indicator name indicator
Hydroxyl value mgKOH/g 29~33 ~ 33
Viscosity MPa s/25℃ ≤ 6000
Moisture% ≤0.05
The PH value is 6-9
Solid content% 42.5 0.5
Residual monomer ppm ≤ 100
POP40
I. Purpose and description:
POP40 is a high activity and high solid content polymer polyol, which is widely used, mainly used in high resilience foam, hot film plastic soft foam, semi-rigid foam, self-skinning foam, reactive injection molding (RIM) products and so on.
Second, the implementation standards:
Enterprise standard
Fourth, technical indicators.
1 appearance
Milky white liquid
2, physical and chemical performance indicators
Indicator name indicator
Hydroxyl value mgkoh/g 19 ~ 23
Viscosity MPa s/25℃ ≤ 7000
Moisture% ≤0.05
The PH value is 6-9
Solid content% 40 1
Residual monomer ppm ≤ 100
Pop -48
I. Purpose and description:
POP-48 is a polymer polyol with high solid content, which is widely used, mainly used in high resilience foam, thermoformed soft foam, high hardness block foam products and so on.
Second, the implementation standards:
Enterprise standard
Third, technical indicators.
1 appearance
Milky white liquid
2, physical and chemical performance indicators
Indicator name indicator
Hydroxyl value mgKOH/g 26~30 ~ 30
Viscosity MPa s/25℃ ≤ 7000
Moisture% ≤0.05
The PH value is 6-9
Solid content% 47 0.5
Residual monomer ppm ≤ 100
BDO
Alias: 1, 4- dihydroxybutane
English name: 1, 4- propanediol; 1, 4- butanediol; 1, 4- dihydroxybutane
Structural formula: hoch2ch2oh
Molecular formula: C4H 10O2.
Colorless oily liquid, flammable, miscible with water. Soluble in methanol, ethanol and acetone, slightly soluble in ether. The boiling point is 235℃ and the melting point is 20℃. 1℃, flash point (opening) 12 1℃, ignition point 370℃, refractive index 1.446.
Toxicity and protection: toxic. When drinking on patients or injured skin, anesthesia will first occur, causing special lesions in the liver or kidney, and then sudden death due to central nervous system paralysis. Production equipment should be sealed to prevent leakage, and operators should wear protective equipment. People with skin trauma are strictly forbidden to touch this product.
Packaging, storage and transportation: use aluminum, stainless steel, galvanized iron drums or plastic drums. Or use tank cars to store and transport flammable and toxic substances according to regulations. Under the condition of closed packaging and no heat, the storage time is not limited; Under natural conditions, it does not explode or spontaneously ignite, but it is flammable.