Preparation method of low crystalline, mildew-proof and water-resistant urea resin

A urea-formaldehyde resin, low crystallization technology, applied in the direction of aldehyde/ketone condensation polymer adhesives, adhesive types, adhesive additives, etc., can solve crystallization, affect adhesive water resistance and bonding strength, affect adhesive The uniformity of adhesive bonding and other issues can be solved, and the preparation process is simple, the aggregation probability of urea-formaldehyde resin colloidal particles is reduced, and the effect of easy operation is achieved.

Active Publication Date: 2017-11-07
WUHAN INSTITUTE OF TECHNOLOGY
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] At present, methods such as lower formaldehyde / urea molar ratio, batch addition of urea, reaction temperature and reaction time have played a very good effect on reducing the release of free formaldehyde, but the use of more urea is likely to cause crystallization of urea-formaldehyde resin, thus It affects the uniformity of adhesive bonding, and also affects the water resistance and bonding strength of the adhesive; in addition, the anti-mildew performance of the urea-formaldehyde resin prepared by the prior art needs to be improved

Method used

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  • Preparation method of low crystalline, mildew-proof and water-resistant urea resin

Examples

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Embodiment 1

[0026] (1) Add 100 parts by weight of formaldehyde solution (concentration is 37%), urea of ​​30 parts by weight in 500mL flask; Regulate system with aqueous sodium hydroxide solution (concentration is 20%) or sodium carbonate solution (concentration is 20%) The pH value is 7.5, after incubating in a water bath at 65°C for 30 minutes, slowly raise the temperature of the water bath to 85°C, and incubate for 30 minutes;

[0027] (2) Add the cetyltrimethylammonium bromide of 0.5% formaldehyde aqueous solution weight part to reaction system, regulate the pH value of reaction system to 4.0 with formic acid aqueous solution (concentration is 20%) simultaneously, measure once every 10 minutes Cloud point, when the sample is dripped into room temperature water and is in the form of white clouds, adjust the pH value of the reaction system to 6.0 with aqueous sodium hydroxide solution (concentration is 20%) or aqueous sodium carbonate solution (concentration is 20%), and drop into 12 par...

Embodiment 2

[0030] (1) Add 100 parts by weight of formaldehyde aqueous solution (concentration is 37%), urea of ​​30 parts by weight in the 500mL flask; Regulate system pH value with aqueous sodium hydroxide solution or sodium carbonate aqueous solution to be 9.0, insulate in 75 ℃ of water baths 30 Minutes later, the temperature of the water bath was slowly raised to 92°C and kept for 60 minutes;

[0031] (2) Add the cetyltrimethylammonium bromide of 5.0% formaldehyde aqueous solution weight part to reaction system, regulate the pH value of reaction system to 5.5 with formic acid aqueous solution (concentration is 20%) simultaneously, measure once every 10 minutes Cloud point, when sampling is dripped into the water and is white cloud, adjust the pH value of reaction system with aqueous sodium hydroxide solution (concentration is 20%) or sodium carbonate aqueous solution (concentration is 20%) to be 6.5, drop into 18 parts by weight of urea; 45 minutes;

[0032] (3) Cool the reaction sys...

Embodiment 3

[0034] (1) Add 100 parts by weight of formaldehyde aqueous solution (concentration is 37%), 33 parts by weight of urea in a 500mL flask; adjust the pH value of the system to 8.5 with aqueous sodium hydroxide or sodium carbonate aqueous solution, and incubate in a water bath at 70°C for 30 Minutes later, the temperature of the water bath was slowly raised to 88°C and kept for 40 minutes;

[0035] (2) Add the cetyltrimethylammonium bromide of 2.5% formaldehyde aqueous solution weight part to reaction system, regulate the pH value of reaction system to 4.5 with formic acid aqueous solution (concentration is 20%) simultaneously, measure once every 10 minutes Cloud point, when sampling is dripped into water and is white cloud, adjust the pH value of the reaction system with aqueous sodium hydroxide solution (concentration is 20%) or sodium carbonate aqueous solution (concentration is 20%) to be 6.3, drop into 14 parts by weight of urea; 35 minutes;

[0036] (3) Cool the reaction s...

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Abstract

The invention belongs to the field of urea resin timber adhesives, and particularly relates to a preparation method of low crystalline, mildew-proof and water-resistant urea resin. The method comprises the following steps: S1, adding alkyl quaternary ammonium salt in a methylol urea compound, meanwhile, adjusting the pH value of a reaction system by using a formic acid water solution, sampling for observation, adjusting the pH value of the system by using an alkaline solution when the sample drops into water and shows the shape of white cloud, adding urea, heating and preserving heat; S2, cooling the reaction system in step S1, adding urea, adjusting the pH value of the system by using the alkaline solution, preserving heat, cooling, discharging a material to obtain a urea resin adhesive. The preparation process of the low crystalline, mildew-proof and water-resistant urea resin adhesive is simple and easy to operate. The urea resin adhesive prepared by the method is suitable for splicing man-made boards such as plywood, chipboard and fiberboard.

Description

technical field [0001] The invention belongs to the field of urea-formaldehyde resin wood adhesives, and in particular relates to a preparation method of low-crystallization, mildew-proof and water-resistant urea-formaldehyde resin. Background technique [0002] Urea-formaldehyde resin has the advantages of rich and easy-to-obtain raw materials, low production cost, fast curing, good operability, and high bonding strength. It is currently the most used variety in wood adhesives, accounting for more than 80% of wood adhesives. , mainly used for bonding plywood, particleboard, medium density fiberboard, etc. However, the current urea-formaldehyde resin has the disadvantages of formaldehyde release and water resistance during use, which limits the application of urea-formaldehyde resin. Therefore, it is of great significance to develop urea-formaldehyde resin adhesives with low formaldehyde emission and excellent water resistance. [0003] By changing the molar ratio (F / U) of...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08G12/12C08K5/19C09J161/24C09J11/06
CPCC08G12/12C08K5/19C09J11/06C09J161/24
Inventor 张云飞吴艳光杜飞鹏李亮鄢国平
Owner WUHAN INSTITUTE OF TECHNOLOGY
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