Method for preparing modified urea-formaldehyde resin powder material

A technology of urea-formaldehyde resin and powder materials, which is applied in the field of preparation of modified urea-formaldehyde resin powder materials, can solve the problems of low free formaldehyde content, high free formaldehyde content, and failure to meet environmental protection requirements, and achieve the reduction of formaldehyde release. and store convenient effects

Inactive Publication Date: 2008-06-18
INST OF WOOD INDUDTRY CHINESE ACAD OF FORESTRY
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Problems solved by technology

[0007] The purpose of the present invention is to overcome the shortcoming that the free formaldehyde content of the melamine modified urea-formaldehyde resin prepared by the existing preparation method is relatively high and cannot meet the requirements of envir

Method used

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Examples

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preparation example Construction

[0018] According to a preferred embodiment of the present invention, the preparation method of the modified urea-formaldehyde resin powder material provided by the present invention includes the following steps: adjusting the pH of a part of the formaldehyde solution to 8-9, heating to 40-70°C, and then adding urea , after the feeding is completed, raise the temperature to 80-95°C, and stir the reaction at this temperature for 10-30 minutes, then adjust the temperature to no more than 85°C, adjust the pH value to 4-6, and continue to stir the reaction until the obtained product The miscibility of water is 1.0-2.5 times; then lower the temperature to 40-60°C, adjust the pH to 8-9, add another part of formaldehyde or its solution, and add the first batch of formaldehyde under the conditions of this temperature and pH value Urea-formaldehyde resin modifier, adjust the reaction temperature to 75-90°C, pH value to 9.0-9.5, stir the reaction until the water miscibility of the obtaine...

Embodiment 1

[0022] This example is used to illustrate the preparation method of the modified urea-formaldehyde resin powder material provided by the present invention.

[0023] 416.67 grams of concentration is 36% formalin (formaldehyde is 5 moles) to join in the 1000 milliliters of four-neck flasks with stirrer, condenser and thermometer, with concentration is the sodium hydroxide aqueous solution of 20% by weight. The formalin was adjusted to pH 8.2 and heated to 50°C, then 151.67 g of urea was added with stirring, the temperature was raised to 90°C and stirred at this temperature for 15 minutes. Then the reaction temperature is reduced to 85°C, and the pH value of the reaction system is adjusted to 5.0 with a concentration of 10% by weight aqueous formic acid, and the stirring reaction is continued until the water miscibility of the product obtained in the flask is 2.5 times, and then cooled to 60°C. The sodium hydroxide solution that is 20% by weight is that the pH value of reaction s...

Embodiment 2

[0029] This example is used to illustrate the preparation method of the modified urea-formaldehyde resin powder material provided by the present invention.

[0030] 416.67 grams of concentration is 36% formalin (formaldehyde is 5 moles) to join in the 1000 milliliters of four-neck flasks with stirrer, condenser and thermometer, with concentration is the sodium hydroxide aqueous solution of 20% by weight. The formalin was adjusted to pH 8.2 and heated to 50°C, then 151.67 g of urea was added with stirring, the temperature was raised to 90°C and stirred at this temperature for 15 minutes. Then the reaction temperature is reduced to 85°C, and the pH value of the reaction system is adjusted to 5.0 with a concentration of 10% by weight aqueous formic acid, and the stirring reaction is continued until the water miscibility of the product obtained in the flask is 1.0 times, and then cooled to 60°C. Adding 104.69 grams of formalin with a concentration of 36% after the pH value of the ...

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Abstract

The present invention provides a preparation method of modified urea formaldehyde resin powder material. The method firstly mixes the product obtained in the reaction between formaldehyde and urea and the urea formaldehyde resin modified agent, and then powderizes the liquid of modified urea formaldehyde resin; wherein, the urea formaldehyde resin modified agent should be added at least for two times. The content of dissociating formaldehyde of the urea formaldehyde resin obtained from the preparation method of modified urea formaldehyde resin provided by the present invention is quite low, thus greatly reducing the formaldehyde burst size of artificial board products in timber manufacturing process. For example, the content of dissociating formaldehyde of the modified urea formaldehyde resin provided by the present invention can be reduced to no more than 0.20 percent, so the veneer prepared by the modified urea formaldehyde resin can meet E1(is less than or equal to 1.5mg/L) stipulated in the international standard. In addition, the modified urea formaldehyde resin powder material provided by the present invention is powder, which is conducive to storage and transport.

Description

technical field [0001] The invention relates to a preparation method of a modified urea-formaldehyde resin powder material. Background technique [0002] Urea-formaldehyde resins, especially melamine-modified urea-formaldehyde resins (MUF), are widely used in the wood manufacturing industry for bonding wood or as adhesives in the production of wood-based materials, such as for particleboard, plywood and various fiberboards. in production. Urea-formaldehyde resin adhesives currently on the market are generally divided into urea-formaldehyde resin solutions and urea-formaldehyde resin powder materials. Urea-formaldehyde resin solution has the advantage of being convenient to use, but has the disadvantage of inconvenient storage and transportation. The urea-formaldehyde resin powder material is just the opposite. When using it, it is necessary to use a solvent to prepare the urea-formaldehyde resin powder material into a urea-formaldehyde resin solution before use, but it is ...

Claims

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Application Information

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IPC IPC(8): C08J3/12C08L61/32C08G12/40C08K5/3492
Inventor 秦特夫李改云黄洛华
Owner INST OF WOOD INDUDTRY CHINESE ACAD OF FORESTRY
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