A kind of low viscosity liquefaction modified MDI and preparation method thereof

A low-viscosity, modified technology, applied in the direction of adhesives, adhesive types, polyurea/polyurethane adhesives, etc., can solve problems such as difficulty in guaranteeing application performance, gas generated by side reactions, and high initial system viscosity, etc., to avoid The effects of intense heat release, high reactivity, and easy control of process conditions

Active Publication Date: 2021-01-01
ANHUI UNIVERSITY OF ARCHITECTURE
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0002] 4,4'-Diphenylmethane diisocyanate (MDI) is one of the important monomers for the preparation of polyurethane due to its high reactivity and rigid groups. However, it is solid at room temperature, which brings a lot of inconvenience to its direct application at room temperature.
Usually, MDI and macromolecular polyols are directly prepared into NCO-terminated prepolymers, which have low NCO content, poor stability, and high viscosity.
When preparing cast elastomers at room temperature, due to the high viscosity of the initial system, the side reactions produce gas, which cannot be discharged in time, resulting in the formation of air bubbles, resulting in a decline in product quality and difficult to guarantee application performance.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] A preparation method of low-viscosity liquefied modified MDI, comprising the following steps,

[0024] a) In a reactor with a temperature control, stirring, and reflux condensation device, under the protection of an inert gas, add MDI for heating, and keep warm at 50°C until the MDI melts into a liquid;

[0025] b) heating up to 78°C, adding catalyst A and monohydric small molecule alcohol, the reaction is complete; then cooling down to 60°C, adding macromolecular polyol, the reaction is complete;

[0026] c) Add stabilizer B, end the experiment after 0.5h, cool down to room temperature, and a colorless transparent viscous liquid can be obtained.

[0027] In step b, the macromolecular polyol is used as polyether diol, and it is vacuum-dried for 20 hours at a temperature of 110° C. and a vacuum degree of 0.01 MPa.

[0028] Catalyst A in step b is organic zinc, and its mass addition is 0.01% of the MDI monomer.

[0029] In step b, the monohydric small molecule alcohol i...

Embodiment 2

[0038] A preparation method of low-viscosity liquefied modified MDI, comprising the following steps,

[0039] a) In a reactor with temperature control, stirring, and reflux condensing devices, under the protection of high-purity nitrogen, add MDI for heating, and keep warm at 50°C to 55°C for 0.5h until the MDI melts into a liquid;

[0040] b) Raise the temperature to 78°C-98°C, add the formulated amount of catalyst A and small monohydric alcohol, and react for 1.5 hours; then lower the temperature to 60°C-75°C, add the formulated amount of macromolecular polyol, and react for 3 hours;

[0041] c) Add stabilizer B, finish the experiment after 1 hour, cool down to room temperature, and a colorless transparent viscous liquid can be obtained.

[0042] In step b, the macromolecular polyol is used as polyether diol, and vacuum-dried for 20-30 hours at a temperature of 110-120° C. and a vacuum degree of 0-0.05 MPa.

[0043] The catalyst A in the step b is organic zinc, and its mass...

Embodiment 3

[0053] A preparation method of low-viscosity liquefied modified MDI, comprising the following steps,

[0054]a) In a reactor with a temperature control, stirring, and reflux condensation device, under the protection of an inert gas, add MDI for heating, and keep warm at 55°C until the MDI melts into a liquid;

[0055] b) heating up to 98°C, adding catalyst A and monohydric small molecule alcohol, the reaction is complete; then cooling down to 75°C, adding macromolecular polyol, the reaction is complete;

[0056] c) Add stabilizer B, finish the experiment after 2 hours, cool down to room temperature, and a colorless transparent viscous liquid can be obtained.

[0057] In step b, the macromolecular polyol is used as polyether diol, and vacuum-dried for 30 hours at a temperature of 120° C. and a vacuum degree of 0.05 MPa.

[0058] Catalyst A in step b is organozinc, and its mass addition is 0.04% of the MDI monomer.

[0059] In step b, the monohydric small molecule alcohol is a...

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Abstract

The invention belongs to the technical field of chemistry and particularly discloses low-viscosity liquefaction modified MDI (4,4'-diphenylmethane diisocyanate) and a preparation method thereof. The liquefaction modified MDI has the viscosity of 310-380 mPa.s and the NCO content of 18%-21%. The method comprises the steps as follows: a) MDI is added to a reactor provided with temperature control, stirring and reflux condensation devices to be heated under the protection condition of inert gas, and the temperature is kept at 50-55 DEG C until MDI is molten into a liquid; b) the temperature is increased to 78-98 DEG C, a catalyst A and mono-hydroxyl small-molecular alcohol are added, the mixture reacts completely, then, the temperature is decreased to 60-75 DEG C, and macromolecular polyols are added; c) a stabilizer B is added, the experiment is ended after 0.5-2 h, and the temperature is decreased to the room temperature. The method is low in raw material cost, simple in process and easy to control in process condition when used for synthesizing the low-viscosity liquefaction modified MDI. The low-viscosity liquefaction modified MDI has high reaction activity and good storage stability and can be used for preparing room-temperature casting polyurethane elastomers, coatings, adhesives and sealants.

Description

technical field [0001] The invention belongs to the technical field of chemical industry, and specifically relates to a low-viscosity liquefied modified MDI and a preparation method thereof. Background technique [0002] Due to its high reactivity and rigid group, 4,4'-diphenylmethane diisocyanate (MDI) is one of the important monomers for the preparation of polyurethane. However, it is solid at room temperature, which brings many inconveniences to its direct application at room temperature. Therefore, without changing the main structure and properties of MDI, it is of great significance to directly transform it from a solid state at room temperature to a liquid state. Usually, MDI and macromolecular polyols are directly prepared into NCO-terminated prepolymers, which have low NCO content, poor stability, and high viscosity. When preparing castable elastomers at room temperature, due to the high viscosity of the initial system, the side reactions produce gas, which cannot b...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C08G18/76C08G18/66C08G18/48C08G18/30C08L75/08C09D175/08C09J175/08
CPCC08G18/282C08G18/4825C08G18/6666C08G18/7671C08L75/08C09D175/08C09J175/08
Inventor 李真王台刘瑾叶青霞
Owner ANHUI UNIVERSITY OF ARCHITECTURE
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