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Modified lignin and urea-formaldehyde resin synthesized from same and preparation methods of modified lignin and urea-formaldehyde resin

A technology of lignin and modification, applied in the direction of adhesive types, aldehyde/ketone condensation polymer adhesives, adhesives, etc. Adhesive manufacturing cost and other issues, to achieve the effect of good market prospects, high bonding strength, moderate storage period

Inactive Publication Date: 2011-11-16
BEIJING UNIV OF CHEM TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] On the one hand, these traditional modification methods will increase the manufacturing cost of the adhesive, and on the other hand, they cannot meet the requirements of environmental protection and high strength at the same time.
Many of the prepared adhesives still retain a large amount of free formaldehyde, unstable methylene ether bonds and methylol groups, and reversible reactions will occur during the use of the resin, releasing formaldehyde to the surrounding environment, and this process It is long-lasting and will seriously endanger people's health
Or the formaldehyde emission is very low but the ideal bonding strength cannot be achieved

Method used

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  • Modified lignin and urea-formaldehyde resin synthesized from same and preparation methods of modified lignin and urea-formaldehyde resin
  • Modified lignin and urea-formaldehyde resin synthesized from same and preparation methods of modified lignin and urea-formaldehyde resin
  • Modified lignin and urea-formaldehyde resin synthesized from same and preparation methods of modified lignin and urea-formaldehyde resin

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0036] Add 70g of sodium lignosulfonate to the beaker, add 85.5g of water to prepare an aqueous solution, add 0.2g of 20% sodium hydroxide aqueous solution, shake well, and let stand for 12 hours.

[0037] Add 141g of lignin solution with a mass fraction of 45% into a 500ml four-neck flask, turn on the stirring device, raise the temperature to 70°C, add 30g of formaldehyde solution with a mass fraction of 37.45%, keep the pH of the system at 9.5, and raise the temperature to 70°C After ℃, keep warm for 60min; add 19.5g of melamine to adjust the pH of the system to 9.5, react for 3 hours, cool and discharge.

[0038]In a 500ml four-necked bottle equipped with a reflux condensing device and a stirring device, add 168.39 g of 37.45% formaldehyde aqueous solution and 63.03 g of urea, turn on the stirring device, add 20% aqueous sodium hydroxide solution dropwise to adjust the pH of the system to 9.2, and start heating at the same time ;When the temperature rises to 85°C, keep it w...

Embodiment 2

[0040] In the synthesis of modified lignin in this embodiment, the mass fraction of sodium lignosulfonate aqueous solution is 40%, and the addition amount is 120 parts by weight, and the others are the same as in Example 1.

Embodiment 3

[0042] In the synthesis of modified lignin in this embodiment, the mass fraction of sodium lignosulfonate aqueous solution is 40%, and the addition amount is 160 parts by weight, and the others are the same as in Example 1.

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Abstract

The invention discloses a modified lignin and a urea-formaldehyde resin synthesized from same and preparation methods of the modified lignin and the urea-formaldehyde resin, belonging to the field of bonding agents used in wood processing. A technological synthetic route with weak base-weak acid-weak base is adopted, the molar ratio of formaldehyde to urea is controlled during an addition stage to generate a reasonable structure, the modified lignin as well as residual hydroxymethyl and free formaldehyde are added at the later stage of reaction in order to accomplish reaction, thus the content of methylene ether link (-CH2-O-CH2-) and the content of hydroxymethyl in the resin are reduced to a certain extent, the formaldehyde emission of the resin is lowered, and simultaneously, higher bonding strength and water resistance are ensured. The urea-formaldehyde resin in the invention is simple and brief in process and low in cost, the formaldehyde emission of the plate prepared by adoptingthe bonding agent reaches the E0-level standard and the plate can maintain high bonding strength after being cooked in hot water. The modified lignin is simple in synthesis method and low in cost andis especially suitable for the modification of the urea-formaldehyde resin with low molar ratio.

Description

technical field [0001] The invention relates to a modified lignin, a urea-formaldehyde resin adhesive synthesized by using the modified lignin and a preparation method of the two. The adhesive is suitable for an adhesive required for wood processing. Background technique [0002] At present, the total output of wood-based panels in my country has exceeded 113 million m 3 , with an average annual growth rate of more than 10%, has become the world's largest wood-based panel producer, and the annual consumption of adhesives for wood-based panel production (100% solid content) has exceeded 8 million tons. Urea-formaldehyde resin glue has become the most widely used and used adhesive in the wood industry due to its easy availability of raw materials and low cost. However, due to the large amount of free formaldehyde remaining in the urea-formaldehyde resin, and the presence of unstable groups such as methylene ether and methylol on its polymer chain structure that can decompose ...

Claims

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Application Information

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IPC IPC(8): C08H7/00C08G12/40C08G12/12C09J161/32
Inventor 李效玉刘海春叶俊王海侨邱藤
Owner BEIJING UNIV OF CHEM TECH
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