Environment-friendly urea-formaldehyde resin adhesive, preparation method and application thereof

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 sufficient curing effect

Active Publication Date: 2019-10-15
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. Add 4000g of industrial formaldehyde (formaldehyde aqueous solution with a concentration of 37wt%, the same below) to the reactor, stir at a speed of 50r / min while heating to 30°C, add 1040g of industrial urea, and stir for 5 minutes;

[0026] S2. Continue heating the reaction solution obtained in step S1 to 50° C., dropwise add aqueous sodium hydroxide solution (20 wt %) to adjust the pH value of the system to 7.5, then add 480 g of urea, and stir for 30 minutes;

[0027] S3, continue to heat the reaction solution gained in step S2 to 90° C., stop heating, keep at this temperature, start to slowly add the first batch of ammonium chloride (10wt% ammonium chloride aqueous solution, the same below), when the pH of the system Stop dripping when the pH value is adjusted to about 7.5, and react for 10 minutes; start to slowly add the second batch of ammonium chloride aqueous solution, stop dropping when the pH value of the system is adjusted to about 6.5, and react for 10...

Embodiment 2

[0041]Prepare environment-friendly urea-formaldehyde resin glue according to the method for embodiment 1, difference is, the addition amount of urea (being step S8) for the 4th time is brought up to 980g, makes the mol ratio of formaldehyde and urea be 1.4:1 in the whole reaction process, obtains 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 value: 7-8

[0046] Storage period: ≥3 months

[0047] Water resistance: use honeysuckle as raw material and the environmentally friendly urea-formaldehyde resin glue as an adhesive to manufacture wood-based panels, and soak the wood-based panels in water at room temperature for 24 hours. As a result, the thickness of the wood-based panels increases by 5%, and the structure is complete and good.

[0048] Mechanical properties: The wood-based panel is made of honeysuckle as...

Embodiment 3

[0050] Prepare environment-friendly urea-formaldehyde resin glue according to the method for embodiment 1, difference is, the addition amount of urea (being step S4) is reduced to 342g for the 3rd time, make the mol ratio of formaldehyde and urea be 1.8:1 in the whole reaction process, obtain 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 value: 7-8

[0055] Storage period: ≥3 months

[0056] Water resistance: use honeysuckle as raw material and the environmentally friendly urea-formaldehyde resin glue as an adhesive to manufacture wood-based panels. The wood-based panels are soaked in water at room temperature for 24 hours. As a result, the thickness of the wood-based panels increases by 3%, and the structure is complete and good.

[0057] Mechanical properties: The wood-based panel is made of honeysuckle as r...

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Abstract

The invention belongs to the field of adhesives, and discloses an environment-friendly urea-formaldehyde resin adhesive, a preparation method and application thereof. The preparation method comprisesthe following steps: heating a formaldehyde solution to be 30 to 40 DEG C, adding urea to perform reaction for 2 to 10min, heating the solution to be 45 to 65 DEG C, then adjusting the pH value of a system to be 6.5 to 8 through alkali liquor, adding urea to perform reaction for 20 to 40min, heating the system to be 85 to 95 DEG C, then stopping heating, adding ammonium chloride in four lots at the temperature, so as to perform curing reaction, then adjusting the pH value to be 6.5 to 8 through alkali liquor and ammonia, adding urea to reduce the temperature to be 78 to 85 DEG C, performing reaction for 30 to 50min, starting to heat up when the temperature is reduced to 72 to 76 DEG C, adding melamine when the temperature is increased to be 82 to 88 DEG C, and performing thermal reaction for 20 to 40min; adding thiourea when the temperature is reduced to be 73 to 78 DEG C, and performing thermal reaction for 5 to 15min; adjusting the pH value to be 9 plus or minus 0.3 through alkali liquor when the temperature is reduced to be 68 to 72 DEG C; adding urea when the temperature is reduced to be 63 to 67 DEG C, performing reaction for 20 to 40min, and cooling the system to be room temperature. The environment-friendly urea-formaldehyde resin adhesive is low in the content of free formaldehyde and high in strength.

Description

technical field [0001] The invention belongs to the field of adhesives, and in particular 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 an adhesive commonly used in wood bonding and composite processing. It is a high-molecular urea-formaldehyde resin polymerized by formaldehyde and urea under acid or alkali catalyzed conditions. It is formed by reacting with an amine curing agent. of thermosetting resins. Urea-formaldehyde resin glue is an adhesive with high bonding strength, water resistance, heat resistance and low cost. It has been widely used in the processing of plywood, particle board, chipboard, blockboard, fiberboard, straw board and other wood products and paper products. and other materials, its consumption accounts for about 80% of the total glue consumption in the wood industry. The urea-formaldehyde resin glue prepared ...

Claims

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Application Information

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Patent Type & Authority Applications(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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