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Preparing method for water soluble urea resin

A urea-formaldehyde resin and water-soluble technology, which is applied in the field of preparation of water-soluble urea-formaldehyde resin, can solve the problems of slow curing speed, incomplete depolymerization of paraformaldehyde, and decreased reactivity of the resin, so as to ensure stable storage and avoid curing speed slowing down, increasing the effect of water solubility

Inactive Publication Date: 2006-06-28
CNOOC CHANGZHOU PAINT & COATINGS IND RES INST
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, due to the incomplete depolymerization of paraformaldehyde, after the urea-formaldehyde resin is dissolved in water, there are still insolubles
If liquid formaldehyde is used to replace solid paraformaldehyde, although the problem of incomplete depolymerization of paraformaldehyde is overcome, the amount of water in the system increases, resulting in insufficient etherification of the resin and a decrease in water solubility. Therefore, water must be removed before etherification. This complicates the production process; although the high etherification with a large amount of methanol improves the water solubility of the resin, the reactivity of the resin will decrease due to the high etherification, and the curing speed will slow down.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0011] 2. Synthesis process:

[0012] Add formaldehyde into the reaction kettle according to the above formula, slowly add ammonia water dropwise under stirring to react with formaldehyde. After adding ammonia water, adjust the pH to 9-10, add urea, slowly raise the temperature to 70-80°C, and keep warm for half an hour to complete hydroxymethylation. Add methanol, use 10% hydrochloric acid to adjust the pH to about 4.5, keep warm at 80°C for etherification and condensation, the viscosity of the system reaches 1.5-2.5 seconds (Grignard tube, 25°C), adjust the pH to 7 with 20% sodium hydroxide aqueous solution ~8. Vacuum dehydration concentrates the resin, and after reaching the dehydration amount calculated from the set solid content, cool down to 40°C, filter, and pack to obtain water-soluble urea-formaldehyde resin.

Embodiment 2

[0028] 2. Synthesis process:

[0029] Add formaldehyde into the reaction kettle according to the above formula, slowly add monoethanolamine dropwise under stirring, and monoethanolamine reacts with formaldehyde. After adding monoethanolamine, adjust the pH value to 9-10, add urea, slowly raise the temperature to 70-80°C and keep it for half an hour to complete the methylolation, then add methanol and ethanol, and adjust the pH to about 4.5 with 10% hydrochloric acid , Etherification and condensation are carried out at 80° C., and the viscosity of the system reaches 2.0 to 3.0 (Grignard tube, 25° C.). The following operations are the same as in Example 1.

[0030] Test items

Example 1

Comparative example 1

Comparative example 2

Comparative example 3

Example 2

Exterior

Transparent liquid

translucent

Transparent liquid

milky white

Transparent liquid

Solid content, wt%

52.7

52.5

53.0

...

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PUM

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Abstract

A water-soluble urea aldehyde resin is prepared by: taking formaldehyde and urea as materials to be reacted in the present of solified promotor, the mol ratio of aldehyde / urea is 1.75-1.95: 1, etherialize urea weight 5-12% ammonia or ammonia modified, and urea weight 10-50% with C is less than or equal to 3 low carbon chain alcohol. The used formaldehyde is liquid formaldehyde. The pH control system for production is: pH value 9-10 for aldehyde and urea hydroxylmethylating, pH 4-5 for etherialize and condensation, pH 7-8 adjusted for after reaction. The advantages include simple operation, obtained urea aldehyde resin with good water-solubility and water diluted stability, and short time to gel. This prepared resin is especially adapted for non-woven cementation.

Description

technical field [0001] The invention relates to a preparation method of water-soluble urea-formaldehyde resin. Background technique [0002] There are two types of water-based urea-formaldehyde resins: water-dispersible and water-soluble. The former, urea-formaldehyde resin is dispersed in water with colloidal particles, and its appearance is milky white, accounting for more than 80% of the total urea-formaldehyde resin, and is mainly used on artificial boards; the latter, urea-formaldehyde resin is dissolved in water in a molecular state, and its appearance is transparent. Stability is better than water dispersion type. At present, water-soluble urea-formaldehyde resins are prepared mainly by reacting solid paraformaldehyde with urea and highly etherifying them with methanol. However, due to incomplete depolymerization of paraformaldehyde, after the urea-formaldehyde resin is dissolved in water, insoluble matter still exists. If liquid formaldehyde is used to replace sol...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C08G12/36
Inventor 马胜军潘煜怡
Owner CNOOC CHANGZHOU PAINT & COATINGS IND RES INST
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