Method and device for removing free formaldehyde in urea-formaldehyde resin

A technology for urea-formaldehyde resin and free formaldehyde, which is applied in the field of removing free formaldehyde in urea-formaldehyde resin, can solve the problems of high viscosity and restrict the diffusion of free formaldehyde monomers, and achieve the effects of simple structure, reduced process cost and high removal rate.

Inactive Publication Date: 2006-08-23
ZHONGBEI UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

In addition, the difficult problem of removing free formaldehyde in urea-formaldehyde resin is that the high molecular polymer system of urea-formaldehyde resin has a relatively high viscosity, and the long chain of high molecular polymer has a binding effect on the diffusion movement of small molecule free formaldehyde, and the viscosity of the system is greatly reduced. Limits the diffusion of free formaldehyde monomers in the polymer

Method used

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  • Method and device for removing free formaldehyde in urea-formaldehyde resin
  • Method and device for removing free formaldehyde in urea-formaldehyde resin
  • Method and device for removing free formaldehyde in urea-formaldehyde resin

Examples

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Effect test

Embodiment 1

[0038] Removal of free formaldehyde monomers in urea-formaldehyde adhesives: the amount of high-temperature curing urea-formaldehyde adhesives to be treated is 0.5m 3 / h, the free formaldehyde content is 2.52% (mass ratio).

[0039] First, heat the urea-formaldehyde adhesive with a water bath to raise the temperature of the resin to 70°C, turn on the water bath of the rotating packed bed to maintain the body temperature at about 70°C; turn on the rotating packed bed, and adjust the rotating speed of the rotating packed bed rotor to 2800r / min through a frequency converter. After the rotary packed bed is stabilized (about two minutes), the preheated adhesive is passed into the rotary packed bed, and the preheated hot air with a temperature of 100-110°C is passed into the rotary packed bed at the same time, and passed through the regulating valve Gradually increase the volume to 400m 3 / h. The free formaldehyde content of the treated urea-formaldehyde resin is reduced to less t...

Embodiment 2

[0043] Removal of free formaldehyde monomers in urea-formaldehyde resin: the amount of cold-setting urea-formaldehyde adhesive to be treated in the process is 1m 3 / h, the free formaldehyde content is 1.21% (mass ratio).

[0044] First, heat the urea-formaldehyde resin with a water bath to raise the temperature of the resin to 55°C; turn on the water bath of the rotating packed bed to maintain the body temperature at about 55°C; turn on the vacuum pump; turn on the rotating packed bed, and adjust the rotating speed of the rotating packed bed rotor to 2500r through a frequency converter / min, after the rotary packed bed is stabilized (about two minutes), the preheated urea-formaldehyde resin is passed into the rotary packed bed, and 0.07MPa water vapor is passed into the rotary packed bed at the same time, and the gas volume is gradually increased through the regulating valve up to 5m 3 / h. And maintain the internal vacuum at 10-15kPa; the free formaldehyde content of the tre...

Embodiment 3

[0046] Removal of free formaldehyde monomer in urea-formaldehyde resin: the amount of urea-formaldehyde resin to be treated in the process is 1000kg / h, and the content of free formaldehyde is 3.13% (mass ratio).

[0047] In this embodiment, the process of removing free formaldehyde monomers in the urea-formaldehyde resin is combined with the dehydration process of the urea-formaldehyde resin. Start the discharge of the reaction kettle, turn on the vacuum pump; turn on the water bath circulation of the rotary packed bed, and maintain the body temperature at about 70°C-80°C; turn on the rotary packed bed, and adjust the rotor speed of the rotary packed bed to 1200r / min through the frequency converter. After the rotary packed bed is stabilized (about two minutes), the steam heater before the resin in the reactor opens the material valve at about 70°C and enters the rotary packed bed, and the temperature is about 115°C after heating with 0.20-0.30MPa steam. Enter the rotating pack...

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Abstract

The method of removing free formaldehyde from urea-formaldehyde resin includes: preheating rotary packing bed to 50-80 deg.c, starting the rotary packing bed and regulating rotation speed to 200-2500 rpm, feeding preheated urea-formaldehyde resin into the rotary packing bed, introducing air, water vapor or nitrogen as gas stripping gas via the gas inlet, and diffusing the free formaldehyde to the gas stripping gas for taking out of urea-formaldehyde resin. The present invention has greatly lowered technological cost and great treating amount. The formaldehyde removing apparatus of the present invention has simple structure, easy operation, high formaldehyde removing rate, low power consumption, and other advantages.

Description

technical field [0001] The invention relates to a method for removing free formaldehyde in urea-formaldehyde resin and equipment for realizing the method. Background technique [0002] Urea-formaldehyde resin is a thermosetting resin obtained by chemical addition and polycondensation reaction based on formaldehyde and urea. The chemical reaction in the synthesis process of urea-formaldehyde resin is very complicated. The traditional theory believes that it is mainly divided into two stages: the first stage is the addition reaction stage, that is, under neutral or weak alkaline conditions, urea and formaldehyde undergo methylolation reaction Generate stable polycondensation intermediates such as methylol urea and methylol urea; the second stage is the polycondensation reaction, that is, the resinization stage. Generate high molecular polymers with alternating repeats of methylene bonds or methylene ether bonds. The traditional method in my country produces urea-formaldehyde...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08G12/36C08J11/02
Inventor 刘有智刘振河
Owner ZHONGBEI UNIV
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