Method for whole-process alkaline synthesis of urea resin wood adhesive

A technology for synthesizing urea-formaldehyde resins and wood adhesives, which is applied in the directions of adhesives, adhesive types, aldehyde/ketone condensation polymer adhesives, etc., and can solve the problems that urea-formaldehyde resin cannot be synthesized, and no reports have been reported.

Active Publication Date: 2019-11-15
GUIZHOU UNIV
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Problems solved by technology

This patent provides a method for the whole alkaline synthesis of melamine urea-formaldehyde resin, but it cannot be used for the synthesis of u

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  • Method for whole-process alkaline synthesis of urea resin wood adhesive

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Embodiment 1

[0026] A kind of preparation method of whole course alkaline synthetic urea-formaldehyde resin wood adhesive:

[0027] (1) Add the first metered formaldehyde solution into the reaction kettle, adjust the pH value to 7.5-9.0; add the first urea under stirring, control the molar ratio of formaldehyde to urea at 1.0, and then gradually raise the temperature of the reactant to 90-95°C; the stirring speed is 1500r / min;

[0028] (2) After heat preservation and reaction at 90-95°C for 30 minutes, cool down to 80-85°C, adjust the pH value to 9.0-10.0 with a compound base, add the second formaldehyde solution, and control the molar ratio of formaldehyde to urea is 1.8;

[0029] (3) Add a batch of formaldehyde at 80-85°C for every 30 minutes of heat preservation reaction until the molar ratio of formaldehyde to urea is 2.0, adjust the pH value to 10.0-11.0, then raise the temperature to 90-95°C, keep warm React for 90 minutes;

[0030] (4) Cool down to 70-80°C, adjust the pH value to...

Embodiment 2

[0033] A kind of preparation method of whole course alkaline synthetic urea-formaldehyde resin wood adhesive:

[0034] (1) Add the first metered formaldehyde solution into the reaction kettle, adjust the pH value to 7.5-9.0; add the first urea under stirring, control the molar ratio of formaldehyde to urea at 1.2, and then gradually raise the temperature of the reactant to 90-95°C; where the stirring speed is 2000r / min;

[0035] (2) After heat preservation and reaction at 90-95°C for 60 minutes, lower the temperature to 80-85°C, adjust the pH value to 9.0-10.0 with a compound base, add the second formaldehyde solution, and control the molar ratio of formaldehyde to urea in 1.8;

[0036] (3) At 80-85°C, add a batch of formaldehyde after every 30 minutes of heat preservation reaction until the molar ratio of formaldehyde to urea is 2.1, adjust the pH value to 10.0-11.0, then raise the temperature to 90-95°C, keep warm React for 90-180 minutes;

[0037] (4) Cool down to 70-80°...

Embodiment 3

[0040] A kind of preparation method of whole course alkaline synthetic urea-formaldehyde resin wood adhesive:

[0041] (1) Add the first metered formaldehyde solution into the reaction kettle, adjust the pH value to 7.5-9.0; add the first urea under stirring, control the molar ratio of formaldehyde to urea at 1.4, and then gradually raise the temperature of the reactant to 90-95°C; the stirring speed is 3000r / min;

[0042](2) After heat preservation and reaction at 90-95°C for 90 minutes, cool down to 80-85°C, use a compound base to adjust the pH value to 9.0-10.0, add the second formaldehyde solution, and control the molar ratio of formaldehyde to urea in 2.0;

[0043] (3) Add a batch of formaldehyde at 80-85°C for every 30 minutes of heat preservation reaction until the molar ratio of formaldehyde to urea is 2.2, adjust the pH value to 10.0-11.0, then raise the temperature to 90-95°C, keep warm React for 180 minutes;

[0044] (4) Cool down to 70-80°C, adjust the pH value ...

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Abstract

The invention belongs to the technical field of artificial board production and in particular discloses a method for whole-process alkaline synthesis of a urea resin wood adhesive. In the synthesis process, a composite alkali catalyst is used, the whole synthesis process is implemented under an alkaline condition, and formaldehyde and urea are added for multiple times, specifically, the method comprises the following steps: firstly, adding a formaldehyde solution into a reaction kettle to react with primary urea in different batches, and secondly, adding secondary urea into the reaction kettleto implement reactions in different batches. The urea resin wood adhesive synthesized by using the method has structure performance similar to that of a urea resin synthesized by using an alkali-acid-alkali process, the problem that a primary polymer generated at an alkali reaction stage in the alkali-acid-alkali process can be partially rearranged as a methylene bridge bond at the alkali reaction stage can be solved, and the content of an ether bond in the urea resin can be reduced. By adopting the method, the industry knowledge that a urea resin cannot be synthesized by using an alkali onlyis contradicted, and the blank of synthesizing the urea resin by using the alkali only is made up.

Description

technical field [0001] The invention belongs to the technical field of wood-based panel production, in particular to a method for preparing a whole-process alkaline synthetic urea-formaldehyde resin wood adhesive. Background technique [0002] Urea-formaldehyde resin is the most important basic adhesive in the production of wood-based panels, which has significant advantages such as fast curing speed and low manufacturing cost. [0003] At present, the synthesis process of urea-formaldehyde resin is mainly a three-stage synthesis process of weak base-weak acid-weak base. The formaldehyde-urea molar ratio (F / U) of the process in the first alkaline reaction stage is generally controlled above 2 / 1, and the final molar ratio is reduced by adding the second urea in the final alkaline reaction stage, while achieving the reduction of free The purpose of formaldehyde content. The traditional theory holds that methylolation reaction mainly occurs in the initial alkaline reaction st...

Claims

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Application Information

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IPC IPC(8): C08G12/12C09J161/24
CPCC08G12/12C09J161/24
Inventor 吴志刚梁坚坤李涛洪杜官本张本刚余丽萍曹明
Owner GUIZHOU UNIV
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