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Method for preparing diphenylmethane diisocyanate-trimethylolpropane (MDI-TMP) bridging agent

A technology of bridging agent and organic solvent, which is applied in the field of preparation of MDI-TMP type bridging agent, achieves the effects of low volatility, increased reaction speed, and reduced polymerization difficulty

Inactive Publication Date: 2012-02-15
SUZHOU XIELU NETWORK TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The residual free isocyanate TDI in the TDI-TMP bridging agent is a highly toxic substance, which is very harmful to the human body. In order to reduce the free TDI in the TDI-TMP bridging agent, domestic and foreign scientists have done a lot of research work. Mainly use molecular sieve adsorption method, extraction method, chemical reaction method, azeotropic distillation method, and thin film evaporation method to reduce TDI, and its free content can be reduced to less than 0.1%, but it has not yet reached the international standard

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0017] In a clean and dry container with a condenser, add TMP (1.00kmol) and CH3COOCH2CH3 (80.00kg) solvent, raise the temperature to 40°C-50°C, stir the solution TMP, stop stirring after TMP is completely dissolved, the system temperature Keep it at 40°C-50°C for use.

[0018] In a clean and dry reaction kettle, install a condenser, add MDI (3.20kmol), CH3COOCH2CH3 (257.00kg) and catalyst dibutyltin dilaurate 1.80kg in vacuum metering, close the big cover of the inlet hole after completion, start stirring and slowly Raise the temperature to 60°C. Under the condition of 60°C, slowly add the TMP solution dropwise, the dropping temperature is controlled at 60°C-65°C, and the dropping time is controlled at 2h-2.5h. React at 70°C for 1 hour, then cool to 50°C and discharge to obtain MDI-TMP, a yellow transparent liquid product, with a solid content of 73.43%, viscosity ≥ 1500mPa.s, NCO: 11.05%, free formaldehyde 0.008g / Kg, free TDI 0.02% .

Embodiment 2

[0020] The operation is as in Example 1, the amount of MDI added is 3.60 kmol, and the yellow liquid product MDI-TMP is obtained, with a solid content of 73.88%, viscosity ≥ 1470mPa.s, NCO: 11.85%, free formaldehyde 0.012g / Kg, free TDI 0.045% .

Embodiment 3

[0022] Operation is as embodiment 1, adds catalyst and changes tin protochloride 1.80kg, obtains yellow liquid product MDI-TMP, solid content 73.01%, viscosity >=1490mPa.s, NCO: 10.95%, free formaldehyde 0.009g / Kg, Free TDI0.035%.

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Abstract

The invention discloses a method for preparing a diphenylmethane diisocyanate-trimethylolpropane (MDI-TMP) bridging agent, which comprises the following steps of: (1) fully dissolving measured TMP in ethyl acetate serving as an organic solvent at the temperature of between 30 and 70 DEG C to obtain a solution A; and dissolving MDI in the ethyl acetate serving as the organic solvent, and dripping catalytic amount of dibutyltin dilaurate or stannous chloride to obtain a solution B; and (2) raising the temperature of the solution A to be between 40 and 150 DEG C, dripping the solution B into thesolution A for 0.5 to 5 hours, preserving heat after the solution B is dripped, and reacting the MDI with the TMP at the temperature of between 40 and 150 DEG C for 0.5 to 5 hours to obtain a yellow transparent liquid product MDI-TMP. Therefore, a highly toxic product, namely toluene diisocynate (TDI) is abandoned and the MDI of which the toxicity is far lower than that of the TDI is selected to prepare the bridging agent; and the MDI has high molecular weight and low volatility and is an environment-friendly product in the real sense.

Description

Technical field: [0001] The invention relates to a preparation method of an MDI-TMP type bridging agent. Background technique: [0002] The bridging agent is generally a low molecular weight PU prepolymer with an average functional group of about 3 NCO end groups. The commonly used bridging agent is a prepolymer of trimethylolpropane (TMP), 1,3-propanediol and 2,4-TDI (TDI-100), and the NCO mass fraction is 12% to 13%. The prepolymer with NCO end group is a very important intermediate in the synthesis of polyurethane, because the NCO prepolymer can react with groups such as hydroxyl, carboxyl, amino and other groups substituted for various active wave hydrogen to form a crosslinked structure. The TDI-TMP bridging agent is the largest and most widely used bridging agent in my country. [0003] Generally, the preparation of commonly used TDI-TMP type bridging agent is synthesized by the reaction of TDI and TMP, which is a typical NCO / OH addition reaction, in which TDI is i...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08G18/78C08G18/76C08G18/32C08G18/10
Inventor 钱华张林荣
Owner SUZHOU XIELU NETWORK TECH
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