Preparation method of polyurethane prepolymer with low free isocyanate monomer

A polyurethane prepolymer and isocyanate technology, applied in the field of polyurethane prepolymer, can solve the problems of inability to prepare prepolymers with low free isocyanate monomers, inability to separate isocyanate monomers, and inability to obtain prepolymer products, and achieve NCO Adjustable and controllable content, high NCO content, adjustable and controllable NCO group content

Active Publication Date: 2012-09-12
SOUTH CHINA UNIV OF TECH +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0010] However, since isocyanate monomers have higher boiling points and enthalpy of evaporation than ester solvents, for polyurethane prepolymers prepared from isocyanate monomers with different isomer reactivity, polyurethane prepolymers prepared from isocyanate monomers with low activity The concentration of unreacted isocyanate monomers in the product is large, and the load of the separation device is large, which usually causes the residual isocyanate monomers to be unable to separate completely, and prepolymers with low free isocyanate monomers cannot be prepared; polyurethane prepared from highly reactive isocyanate monomers The concentration of unreacted isocyanate monomer in the prepolymer is small. Before the prepolymer flows to the outlet, the isocyanate monomer and ester solvent have evaporated. Due to the lack of "wetting" of the solvent, the viscosity of the prepolymer will reach very high. Large, "dry steaming" occurs, resulting in the inability to discharge the material and obtain the prepolymer product

Method used

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  • Preparation method of polyurethane prepolymer with low free isocyanate monomer

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0039] 10g of 1,3-propanediol and 65g of trimethylolpropane were used to form a mixed alcohol at 120°C for 2 hours in a vacuum to control its water content to be lower than 0.01%, and it was ready for use; under nitrogen protection, 482g of TDI 100 ( All are composed of 2,4-TDI) and 255g of ethylene glycol ether acetate into the reaction vessel and stirred evenly, maintaining the temperature at 60°C, and then adding the dehydrated mixed alcohol dropwise into the reaction vessel under stirring , adding time for 1 hour. After the dropwise addition, continue to react at 70°C under stirring for 6 hours, control the temperature to below 40°C, cool and discharge to obtain a polyurethane prepolymer;

[0040] The obtained polyurethane prepolymer enters the internally cooled molecular still through a distributor at a feed rate of 10 g / min, the primary separation temperature is controlled at 100°C, the primary cold trap temperature is controlled at 11°C, and the vacuum degree is control...

Embodiment 2

[0042] 31g of ethylene glycol and 32g of trimethylolethane form the mixed alcohol at 150°C, vacuum dehydrated for 4 hours, control its water content to be lower than 0.02%, and stand-by; under nitrogen protection, first 579g TDI80 (80% 2,4-TDI and 20% 2,6-TDI) and 148g of n-butyl acetate were put into the reaction vessel and stirred evenly, the temperature was maintained at 55°C, and then the dehydrated mixed alcohol was added dropwise to the In the above reaction vessel, the dropwise addition time was 1.5 hours. After the dropwise addition, continue to react at 65°C under stirring for 4 hours, control the temperature to below 40°C, cool and discharge to obtain a polyurethane prepolymer;

[0043] The obtained polyurethane prepolymer enters the internally cooled molecular still through the distributor at a feed rate of 7.5g / min, the primary separation temperature is controlled at 130°C, the primary cold trap temperature is controlled at 15°C, and the vacuum degree is controlled...

Embodiment 3

[0045] 49g of 1,4-butanediol and 11g of 1,2,6-hexanetriol to form a mixed alcohol were dehydrated under vacuum for 3 hours at 150°C, and the water content was controlled to be less than 0.01%, and it was ready for use; under the protection of nitrogen, First put 601g TDI80 (composed of 80% 2,4-TDI and 20% 2,6-TDI) and 139g propylene glycol methyl ether acetate into the reaction vessel and stir evenly, keeping the temperature at 40°C, then put the dehydrated mixed alcohol It was added dropwise into the reaction vessel under stirring condition, and the dropwise addition time was 1 hour. After the dropwise addition, continue to react at 45°C under stirring for 3 hours, control the temperature to below 40°C, cool and discharge to obtain a polyurethane prepolymer;

[0046] The obtained polyurethane prepolymer enters the externally cooled film still through a distributor at a feed rate of 6 g / min. The primary separation temperature is controlled at 160° C., the primary cold trap tem...

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Abstract

The invention discloses a preparation method of polyurethane prepolymer with low free isocyanate monomer. The preparation method comprises the following steps of: forming into mixed alcohol by trihydric alcohol and dihydric alcohol under the temperature of 120-150DEG C, and carrying out vacuum dehydration; putting isocyanate monomer and ester solvents into a reactor to keep the temperature at 30-70DEG C, and dropwise adding the mixed alcohol into the reactor; after dropwise adding, continuously reacting for 3-6h under the temperature of 40-70DEG C under stirring, and discharging in a cooling way to obtain polyurethane prepolymer; and separating the obtained polyurethane prepolymer, and adjusting the solid content of polyurethane prepolymer solid and the content of free isocyanate monomer in the separated heavy components by diluted solvent. According to the preparation method, the real continuous production can be realized, all the recovered solvent and isocyanate monomer can be recycled, the zero emission can be realized, and the real clean production can be realized; and the product has the characteristics of being low in viscosity, high and adjustable in NCO value content, low in the content of the free isocyanate monomer, high in solid content, good in compatibility, etc.

Description

technical field [0001] The invention relates to a polyurethane prepolymer, in particular to a preparation method of a polyurethane prepolymer with low free isocyanate monomer. Background technique [0002] Polyurethane is an important product and material used in many industries such as building materials, furniture, coatings, plastics, leather and adhesives. The performance of polyurethane is related to the quality and safety of hundreds of billions of products such as wooden furniture, toys, automobiles, leather, shoes and composite films. The coating film of polyurethane coating has the advantages of high hardness, good toughness, strong chemical resistance and fast drying. It is one of the most widely used solvent-based coatings with excellent performance. Polyurethane coating is composed of two components, one component is alkyd resin, polyester resin and acrylic resin and other hydroxyl substances, and the other key component is polyurethane prepolymer formed by preli...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08G18/82C08G18/32C08G18/12
Inventor 张心亚何勇黄洪殷代武王代民曹树潮梅慈云陈焕钦
Owner SOUTH CHINA UNIV OF TECH
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