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Method for preparing low-free p-phenylene diisocyanate prepolymer

A technology of p-phenylene diisocyanate and prepolymer, which is applied in the field of prepolymer preparation, and can solve problems such as multiple impurities, product discoloration, and increased economic costs

Inactive Publication Date: 2020-06-05
CHANGCHUN INST OF APPLIED CHEMISTRY - CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] U.S. Patent No. 5,703,193 describes a process for reducing residual polyisocyanate monomers, especially PPDI monomers, in prepolymers by co-distilling the reaction product in the presence of two inert solvents, the boiling point of the first inert solvent being The boiling point of the second inert solvent is lower than the boiling point of the diisocyanate monomer, and the boiling point of the second inert solvent is higher than that of the diisocyanate monomer. The two work together to make the internal condensation surface free of diisocyanate crystals. When a solvent is used alone, the condenser occurs Blockage cannot be used, but the use of two solvents increases economic costs, and the removal of high-boiling solvents in heavy components is also a problem, which can only be achieved by increasing the distillation temperature, but PPDI is prone to degradation reactions at high temperatures, resulting in more impurities and discolor the product

Method used

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  • Method for preparing low-free p-phenylene diisocyanate prepolymer
  • Method for preparing low-free p-phenylene diisocyanate prepolymer
  • Method for preparing low-free p-phenylene diisocyanate prepolymer

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preparation example Construction

[0029] figure 1 A schematic flow diagram for the preparation of low free p-phenylene diisocyanate prepolymer provided by the present invention.

[0030] The invention mixes dehydrated polyalcohol, p-phenylene diisocyanate and a single solvent, reacts at 60-70 DEG C, and processes the obtained reaction product in a thin-film evaporator to obtain the treated solvent. The anhydrous polyol and p-phenylene diisocyanate are solutes. In the present invention, the mass ratio of the total mass of the dehydrated polyol and p-phenylene diisocyanate to the single solvent is 1:5 to 1:100, and the mass ratio of p-phenylene diisocyanate and p-phenylene diisocyanate is 10: 1~30:1; In specific embodiment, the substance ratio of described p-phenylene diisocyanate and dehydrated polyol is 20:1; The total mass of described dehydrated polyol and p-phenylene diisocyanate and the mass of described single solvent The ratio is 9:1.

[0031]The boiling point of the single solvent at normal pressure ...

Embodiment 1

[0045] The polyol PTMEG1000 was vacuum dehydrated at 130° C. for 3 hours to remove the moisture in the polyol and set aside. Under a nitrogen atmosphere, at a temperature of 65°C, add 1.16Kg of PPDI to 13.9Kg of diisopropyl adipate solvent and stir evenly to fully dissolve the PPDI, then add 0.36Kg of the above-mentioned polyol into the reactor while stirring, and continue Stir for 3 hours. The molar ratio of PPDI to polyol is 20:1, and the mass ratio of solvent to solute is 9:1. Then add the above mixture into a thin film evaporator, set the internal temperature of the film to 120°C, set the vacuum degree to 40-60Pa, set the condensation temperature to 20-35°C, collect the light component distillate, and measure the NCO value to be 3.85 %.

[0046] Under the protection of nitrogen, pour 8.4Kg of purified diisopropyl adipate into the reactor, add 0.83Kg of PPDI, heat to 65°C, wait until PPDI is completely dissolved, and stir evenly. Keep this temperature, and then add the d...

Embodiment 2

[0051] The polyol PTMEG1000 was vacuum dehydrated at 130° C. for 3 hours to remove the moisture in the polyol and set aside. Under a nitrogen atmosphere, at a temperature of 65°C, add 1.16Kg of PPDI to 13.9Kg of diisopropyl adipate solvent and stir evenly to fully dissolve the PPDI, then add 0.36Kg of the above-mentioned polyol into the reactor while stirring, and continue Stir for 3 hours. The molar ratio of PPDI to polyol is 20:1, and the mass ratio of solvent to solute is 9:1. Then add the above mixture into a thin film evaporator, set the internal temperature of the film to 120°C, set the vacuum degree to 40-60Pa, set the condensation temperature to 20-35°C, collect the light component distillate, and measure the NCO value to be 3.85 %.

[0052] Under the protection of nitrogen, pour 8.4Kg of purified diisopropyl adipate into the reactor, add 1.07Kg of PPDI, heat to 65°C, wait until PPDI is completely dissolved, and stir evenly. Keep this temperature, and then add the d...

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Abstract

The invention provides a method for preparing a low-free p-phenylene diisocyanate prepolymer. The method comprises the following steps: a) mixing dehydrated polyol, p-phenylene diisocyanate and a single solvent, reacting at 60-70 DEG C, and treating the obtained reaction product in a film evaporator to obtain a treated solvent; wherein the single solvent is selected from monoester, diester, lactone, carbonate, aromatic compounds, amide, lactam, polyether or polyketone; b) mixing the treated solvent with p-phenylene diisocyanate, then adding dehydrated polyol by several times, and carrying outa reaction at 60-70 DEG C to obtain a prepolymer; and c) treating the prepolymer in a scraped film evaporator to obtain a light component and a p-phenylene diisocyanate prepolymer, the light componentcomprising a single solvent and p-phenylene diisocyanate. The mass fraction of free PPDI in the prepolymer is reduced to 1-0.1%; PPDI crystals are not separated out in the evaporation process of a film evaporator, and a condenser is not blocked.

Description

technical field [0001] The invention belongs to the technical field of prepolymer preparation, in particular to a method for preparing low free p-phenylene diisocyanate prepolymer. Background technique [0002] Polyurethane has flexible formula, various product forms, and excellent product performance, and its application in various industries is becoming more and more extensive. In addition to cast polyurethane, other types of polyurethane are currently synthesized by the prepolymer method, that is, excess isocyanate and oligomer polyols are synthesized under certain conditions. A method of mixing and molding polymers and chain-extending cross-linking agents. For example, a large excess of isocyanate monomer is usually used to reduce the generation of large molecular weight substances and generate prepolymers with linear and regular structures, such as ABA, ABABA, etc., where A represents diisocyanate and B represents diol. Physical properties of polyurethane elastomers, ...

Claims

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Application Information

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IPC IPC(8): C08G18/76C08G18/48
CPCC08G18/4854C08G18/7614
Inventor 冉祥海高一星聂伟
Owner CHANGCHUN INST OF APPLIED CHEMISTRY - CHINESE ACAD OF SCI
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