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Lignin sulfonate modified urea formaldehyde resin preparation method

A technology of lignosulfonate and urea-formaldehyde resin, which is applied in the field of preparation of lignosulfonate-modified urea-formaldehyde resin, can solve the problem of threats to dominance, little improvement in bonding strength, poor weather resistance and water resistance and formaldehyde sensitivity It can reduce the release of formaldehyde, improve the bonding strength, improve the initial adhesion and water resistance.

Inactive Publication Date: 2006-02-22
INST OF CHEM IND OF FOREST PROD CHINESE ACAD OF FORESTRY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, urea-formaldehyde resin adhesives have two major disadvantages: poor weather resistance, water resistance and sensitivity to formaldehyde release, which will threaten its dominance in the field of wood adhesives
The method of blending and modifying hydroxymethylated lignin with urea-formaldehyde resin often fails to achieve the expected effect, which is because the hydroxymethylated lignin that has not undergone the acidic polycondensation stage cannot form methylene with methylolurea. The base bridge bond, so it does not improve the bonding strength much

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0018] A kind of preparation method of modified urea-formaldehyde resin:

[0019] Step 1: Put formaldehyde, starch and urea accounting for 2% to 21% of the mass of formaldehyde in a reaction system with a pH value of 6.5 to 9.5, heat up to 70 to 90°C, and react for 15 to 80 minutes. The moles of the above formaldehyde and urea The ratio is (2.3:1)~(1.8:1). In this embodiment, formaldehyde, starch and urea accounting for 2%, 21%, 11% or 17% of the formaldehyde mass can be placed at a pH of 6.5, 7 , 8 or 9.5 in the reaction system, heat up to 70, 80 or 90 ° C, react for 15, 20, 35, 65 or 80 minutes, the molar ratio of the above-mentioned formaldehyde to urea is 2.3:1, 1.8:1, 2.0:1 or 2.2 : 1,

[0020] Step 2: Adjust the pH value to 2.5-5.5, add lignosulfonate accounting for 7%-70% of the mass of formaldehyde, and react for 60-180 minutes. Lignosulfonate can be magnesium lignosulfonate, lignosulfonate sodium lignosulfonate or ammonium lignosulfonate, in this embodiment, the pH ...

Embodiment 2

[0024] Put 200g of 36.5% formaldehyde solution into a 500mL four-neck flask, adjust the pH value to 8.0 with triethanolamine, add 10g of starch, 66g of urea, start stirring, heat up to 90°C, keep warm for 30min, and adjust with 50% formic acid solution The pH value is 4.5, add 12g of lignosulfonate, continue to keep warm for 90min, adjust the pH to 5.5 with 30% sodium hydroxide solution, add 28g of urea, keep warm at 85°C for 30min, then adjust the pH with 30% sodium hydroxide solution value is 7.5, add 27g of urea, continue to keep warm for 20min, cool down and discharge. Test their performance separately, and the results are listed in the attached table.

Embodiment 3

[0026] Put 200g of 36.5% formaldehyde solution into a 500mL four-neck flask, adjust the pH value to 9.0 with triethanolamine, add 20g of starch and 80g of urea, start stirring, raise the temperature to 90°C, keep it warm for 30min, and adjust with 50% formic acid solution The pH value is 5.5, add 30g of lignosulfonate, continue to keep warm for 120min, adjust the pH to 6.5 with 30% sodium hydroxide solution, add 24g of urea, keep warm at 85°C for 60min, then adjust the pH with 30% sodium hydroxide solution value is 7.5, add 58g of urea, continue to keep warm for 20min, cool down and discharge. Test their performance separately, and the results are listed in the attached table.

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PUM

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Abstract

The invention discloses a lignin sulfonate modified urea formaldehyde resin preparation method, which comprises loading methyl aldehyde, starch and urea into reaction system, elevating temperature for reacting 15-80 min, adjusting pH to 2.5-5.5, charging lignin sulfonate, reacting 60-180 min, adjusting pH to 4.5-6.5, charging urea again, reacting 10-70 min, finally adjusting pH to 6.5-8.5, charging urea for the third time, reacting 30-90 min, cooling down to below 50 deg. C.

Description

technical field [0001] The invention relates to a method for modifying urea-formaldehyde resin with starch and lignosulfonate, in particular to a preparation method for lignosulfonate-modified urea-formaldehyde resin. Background technique [0002] Urea-formaldehyde resin has the advantages of cheap and easy to obtain raw materials, simple manufacturing process, colorless and transparent, excellent adhesion to lignocellulose, and no pollution to wood, so it has become the synthetic resin glue used in the wood-based panel industry. % of the main type of glue, is currently the largest variety of adhesives. However, urea-formaldehyde resin adhesives have two major disadvantages: poor weather resistance, poor water resistance and sensitivity to formaldehyde release, which will threaten its dominance in the field of wood adhesives. [0003] Starch is a polysaccharide polymer compound composed of glucose, which has a wide range of sources and is cheap. Starch can undergo etherifi...

Claims

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Application Information

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IPC IPC(8): C08G14/12
Inventor 王春鹏金立维储富祥周道兵赵临五
Owner INST OF CHEM IND OF FOREST PROD CHINESE ACAD OF FORESTRY