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A kind of environment-friendly urea-formaldehyde resin glue and its preparation method and application

An environmentally friendly urea-formaldehyde resin and thiourea technology, applied in the direction of adhesives, aldehyde/ketone condensation polymer adhesives, adhesive types, etc., can solve the problems of complex reaction between urea and formaldehyde, and achieve good pre-compression and low cost. , the effect of long storage period

Active Publication Date: 2020-10-02
鹰潭佰伦包装有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The reaction between urea and formaldehyde is very complicated, and it has not been fully studied so far, but the theoretical circle generally agrees that the synthesis of urea-formaldehyde resin is divided into two stages: the first stage is an addition reaction, which is under alkaline conditions. reaction) to generate monohydroxyl, dihydroxyl and trimethylol urea; the second stage is polycondensation reaction, which is dehydration condensation (polycondensation) between methylol compound molecules under acidic conditions, first forming a water-soluble resin. The resinous product transforms into an insoluble, infusible cross-linked resin network in the presence of heating or an acidic curing agent

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] S1, in the reactor, add 4000g industrial formaldehyde (concentration is the formaldehyde solution of 37wt%, the same below), stir with the rotating speed of 50r / min and heat up to 30 ℃ simultaneously, add 1040g industrial urea, stirring reaction 5min;

[0026] S2, the reaction solution obtained in step S1 is continued to be heated to 50 ℃, sodium hydroxide aqueous solution (20wt%) is added dropwise to adjust the pH value of the system to 7.5, then 480g of urea is added, and the reaction is stirred for 30min;

[0027] S3, continue heating the reaction solution obtained in step S2 to 90° C. and then stop heating, keep at this temperature, and start to slowly drop the first batch of ammonium chloride (10wt% ammonium chloride aqueous solution, the same below), when the pH of the system When the pH value of the system is adjusted to about 7.5, stop dripping and react for 10min; start to slowly drip the second batch of ammonium chloride aqueous solution, stop dripping when the...

Embodiment 2

[0041]Prepare the environment-friendly urea-formaldehyde resin glue according to the method of embodiment 1, the difference is that the addition of urea (that is, step S8) for the fourth time is increased to 980g, so that the mol ratio of formaldehyde and urea in the whole reaction process is 1.4:1, obtaining Environmentally friendly urea-formaldehyde resin glue, its performance indicators are as follows:

[0042] Appearance: milky white

[0043] Solid content: 60-75wt%

[0044] Free formaldehyde: 0.15wt%

[0045] pH: 7-8

[0046] Storage period: ≥3 months

[0047] Water resistance: The wood-based panel was manufactured with honeysuckle grass as raw material and the environment-friendly urea-formaldehyde resin glue as adhesive, and the wood-based panel was soaked in water for 24 hours at room temperature.

[0048] Mechanical properties: The wood-based panel is manufactured with the golden silver grass as the raw material and the environmentally friendly urea-formaldehyde r...

Embodiment 3

[0050] Prepare environment-friendly urea-formaldehyde resin glue according to the method of embodiment 1, the difference is that the addition amount of urea (that is, step S4) for the third time is reduced to 342g, so that the molar ratio of formaldehyde and urea in the whole reaction process is 1.8:1, obtaining Environmentally friendly urea-formaldehyde resin glue, its performance indicators are as follows:

[0051] Appearance: milky white

[0052] Solid content: 60-75wt%

[0053] Free formaldehyde: 0.25wt%

[0054] pH: 7-8

[0055] Storage period: ≥3 months

[0056] Water resistance: The wood-based panel was made with honeysuckle grass as raw material and the environmentally friendly urea-formaldehyde resin adhesive as the adhesive. The wood-based panel was soaked in water for 24 hours at room temperature. As a result, the thickness of the wood-based panel increased by 3%, and the structure was complete and good.

[0057] Mechanical properties: The wood-based panel is ma...

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Abstract

The present invention belongs to the field of adhesives, and discloses an environmentally-friendly urea-formaldehyde resin adhesive and a preparation method and use thereof. The preparation method of the environmentally-friendly urea formaldehyde resin adhesive includes: heating a formaldehyde solution to 30-40C, and adding urea for reaction for 2-10 min; heating to 45-650 C, adjusting the pH value of the system to 6.5-8 using an alkaline solution, and adding urea for reaction for 20 40 min; stopping heating after heating to 85-950 C, and adding ammonium chloride in four batches at this temperature for curing reaction; adjusting the pH value to 6.5-8 using an alkaline solution and ammonia water, adding urea, and reducing the temperature to 78-850C for conducting reaction for 30-50 min; starting to conduct heating when the temperature drops to 72-76C, adding melamine when the temperature rises to 82-880C, and keeping the temperature for reaction for 20-40 min; adding thiourea when the temperature drops to 73-780C, and keeping the temperature for reaction for 5-15 min; adjusting the pH value to 9±0.3 using an alkaline solution when the temperature drops to 68-72°C; and adding urea for reaction for 20-40 min when the temperature drops to 63-670C, and cooling the system to room temperature. The resulting environmentally-friendly urea-formaldehyde resin adhesive has low content of free formaldehyde and high strength.

Description

technical field [0001] The invention belongs to the field of adhesives, and particularly relates to an environment-friendly urea-formaldehyde resin adhesive and a preparation method and application thereof. Background technique [0002] Urea-formaldehyde resin (UF) adhesive is a kind of adhesive commonly used in wood bonding and composite processing. It is a polymer urea-formaldehyde resin formed by polymerizing formaldehyde and urea under acid or alkali catalysis conditions. It is formed by reacting with amine curing agents. of thermosetting resins. Urea-formaldehyde resin adhesive is a kind of adhesive with high bonding strength, water resistance, heat resistance and low cost. It has been widely used in processing plywood, particleboard, particle board, blockboard, fiberboard, straw board and other wood products and paper products. And the bonding of other materials, the amount of which accounts for about 80% of the total amount of glue used in the wood industry. The ure...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C08G12/12C09J161/24
CPCC08G12/12C09J161/24
Inventor 罗学涛乐险夏磊黄柳青
Owner 鹰潭佰伦包装有限公司
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