Method for preparing modified urea-formaldehyde resin

A urea-formaldehyde resin and modification technology, which is applied in the field of preparation of modified urea-formaldehyde resin, can solve the problems of low free formaldehyde content, high free formaldehyde content, and failure to meet environmental protection requirements, and achieve the goal of reducing formaldehyde emission and free formaldehyde content Effect

Inactive Publication Date: 2008-03-05
INST OF WOOD INDUDTRY CHINESE ACAD OF FORESTRY
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  • Abstract
  • Description
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Problems solved by technology

[0006] 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

Method used

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Examples

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preparation example Construction

[0014] According to a preferred embodiment of the present invention, the preparation method of the modified urea-formaldehyde resin provided by the present invention includes the following steps: adjust a part of the formaldehyde solution to pH 8-9 and heat it to 40-70°C, then add urea, the addition is complete Then increase 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 to 4-6, and continue to stir the reaction until the resulting product is mixed with water The performance is 1.0-2.5 times; then the temperature is lowered to 40-60℃, and then the pH is adjusted to 8-9, then another part of formaldehyde or its solution is added, and the first batch of urea-formaldehyde resin is added under the conditions of this temperature and pH. Sexual agent, adjust the reaction temperature to 75-90℃, pH value to 9.0-9.5, stir the reaction until the water miscibility of the resulting produc...

Embodiment 1

[0018] This example is used to illustrate the preparation method of the modified urea-formaldehyde resin provided by the present invention.

[0019] 416.67 grams of 36% formalin (5 moles of formaldehyde) was added to a 1000 ml four-necked flask equipped with a stirrer, a condenser and a thermometer, and a sodium hydroxide aqueous solution with a concentration of 20% by weight was used to add Fu The pH value of Ermarin was adjusted to 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 was lowered to 85°C, the pH value of the reaction system was adjusted to 5.0 with an aqueous solution of formic acid with a concentration of 10% by weight, and the stirring was continued until the water miscibility of the product obtained in the flask was 2.5 times, and then the temperature was lowered to 60°C. Then adjust the pH of the reaction system to 8.8 with 20% by...

Embodiment 2

[0024] This example is used to illustrate the preparation method of the modified urea-formaldehyde resin provided by the present invention.

[0025] 416.67 grams of 36% formalin (5 moles of formaldehyde) was added to a 1000 ml four-necked flask equipped with a stirrer, condenser and thermometer, and a sodium hydroxide aqueous solution with a concentration of 20% by weight was used to add Fu The pH value of Ermarin was adjusted to 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 was lowered to 85°C, the pH value of the reaction system was adjusted to 5.0 with an aqueous solution of formic acid with a concentration of 10% by weight, and the stirring was continued until the water miscibility of the product obtained in the flask was 1.0 times, and then the temperature was lowered to 60°C. The pH value of the reaction system was adjusted to 8.8 with 20%...

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Abstract

The process of preparing modified urea-formaldehyde resin includes the contact reaction of formaldehyde and urea, and the mixing of the resultant and the modifier added into urea-formaldehyde resin in at least two times. The modified urea-formaldehyde resin has very low content of free formaldehyde, say, below 0.20 %. When it is used in making artificial board, the artificial board will have very low formaldehyde releasing amount. In addition, the modified urea-formaldehyde resin may be in liquid and powder form, and may be applied in different conditions, including moist condition and outdoor condition.

Description

Technical field [0001] The invention relates to a preparation method of a modified urea-formaldehyde resin. Background technique [0002] Urea-formaldehyde resins, especially melamine-modified urea-formaldehyde resins (MUF), are widely used in wood manufacturing, for bonding wood or as an adhesive in the production of wood-based materials, such as particle board, plywood and various fiberboards in production. Urea-formaldehyde resin is the reaction product of urea and formaldehyde. Due to the poor water resistance and strength of this urea-formaldehyde resin, urea-formaldehyde resin modifiers are generally used to modify the resulting urea-formaldehyde resin to obtain modified urea-formaldehyde resins such as commonly used melamine-modified urea-formaldehyde resins (MUF). The water resistance and strength of this urea-formaldehyde resin are significantly higher than that of unmodified conventional urea-formaldehyde resins. The urea-formaldehyde resin modifier is usually melamine,...

Claims

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Application Information

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IPC IPC(8): C08L61/24
Inventor 秦特夫李改云
Owner INST OF WOOD INDUDTRY CHINESE ACAD OF FORESTRY
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