Synthetic method of melamine-formaldehyde resin

Abstract

The invention provides a synthetic method of melamine-formaldehyde resin. The synthetic method comprises the following steps of firstly adjusting the pH of a formalin solution to 10.0-10.5 with triethanolamine, then mixing melamine solid powder with the formalin solution in proportion, performing heating for raising the temperature to 75-85 DEG C, wherein in the process of heating for raising the temperature, the color of a mixed solution gradually changes clear and transparent from white, and continuing a reaction for 3.5-4.5 hours so as to obtain the melamine-formaldehyde resin; and after the color of the mixed solution gradually changes to clear and transparent from white, adding glycol, wherein the mole ratio of the glycol to the melamine is (0.5 to 1) to (2 to 1). The method is simple in operation process, large in operation flexibility, low in content of free formaldehyde, good in stability, and quite suitable for industrialized production of special polyether products particularly flame resistant type polyether products.

Description

Technical field

[0001] The invention relates to a synthetic method of melamine, in particular to a synthetic method using triethanolamine as a regulator. Background technique

[0002] Melamine resin (MF) has excellent water resistance, heat resistance, aging resistance, chemical resistance, flame retardancy and insulation properties. It can be used to make molding compounds (daily tableware, electrical appliances), wood-based panels (plywood, laminate flooring, and laminates). In addition, it is also widely used as paint, paint crosslinking agent, wood adhesive, paper wet strength agent, fiber textile finishing agent, cement water reducing agent, etc. Melamine resins for different purposes have different synthetic process routes.

[0003] Melamine resin is generally prepared by methylolation reaction of formaldehyde solution and melamine solid powder in neutral or weak alkaline environment. The reaction of melamine and formaldehyde is carried out in stages. First, formaldehyde an...

Examples

Embodiment 1

[0030] Add 243.2g of aqueous formaldehyde solution to a four-necked flask, adjust the pH to 10.0 with triethanolamine, add 126g of melamine, and stir evenly. Place the flask in a water bath and heat to 82°C. After the white solution is completely clear and transparent, continue the reaction for 3.5 hours. Finally, a transparent melamine resin is obtained.

[0031] Among them, the free formaldehyde content is 1.82%, and the hydroxymethyl content is 19.5%.

Embodiment 2

[0033] Add 324.3g of aqueous formaldehyde solution to a four-necked flask, adjust the pH to 10.4 with triethanolamine, add 126g of melamine, and stir evenly. Place the flask in a water bath and heat to 80°C. After the white solution is completely clear and transparent, continue the reaction for 4 hours. Finally, a transparent melamine resin is obtained.

[0034] Among them, the free formaldehyde content is 2.01 and the hydroxymethyl content is 18.8%.

Embodiment 3

[0036] Add 405.4g of aqueous formaldehyde solution to a four-necked flask, adjust the pH to 10.5 with triethanolamine, add 126g of melamine, stir well, place the flask in a water bath and heat to 85°C, and continue the reaction for 4.5 hours after the white solution is completely clear and transparent. Finally, a transparent melamine resin is obtained.

[0037] Among them, the free formaldehyde content is 4.04%, and the hydroxymethyl content is 15.1%.

Technical field

[0001] The invention relates to a synthetic method of melamine, in particular to a synthetic method using triethanolamine as a regulator. Background technique

[0002] Melamine resin (MF) has excellent water resistance, heat resistance, aging resistance, chemical resistance, flame retardancy and insulation properties. It can be used to make molding compounds (daily tableware, electrical appliances), wood-based panels (plywood, laminate flooring, and laminates). In addition, it is also widely used as paint, paint crosslinking agent, wood adhesive, paper wet strength agent, fiber textile finishing agent, cement water reducing agent, etc. Melamine resins for different purposes have different synthetic process routes.

[0003] Melamine resin is generally prepared by methylolation reaction of formaldehyde solution and melamine solid powder in neutral or weak alkaline environment. The reaction of melamine and formaldehyde is carried out in stages. First, formaldehyde an...

Examples

Embodiment 1

[0030] Add 243.2g of aqueous formaldehyde solution to a four-necked flask, adjust the pH to 10.0 with triethanolamine, add 126g of melamine, and stir evenly. Place the flask in a water bath and heat to 82°C. After the white solution is completely clear and transparent, continue the reaction for 3.5 hours. Finally, a transparent melamine resin is obtained.

[0031] Among them, the free formaldehyde content is 1.82%, and the hydroxymethyl content is 19.5%.

Embodiment 2

[0033] Add 324.3g of aqueous formaldehyde solution to a four-necked flask, adjust the pH to 10.4 with triethanolamine, add 126g of melamine, and stir evenly. Place the flask in a water bath and heat to 80°C. After the white solution is completely clear and transparent, continue the reaction for 4 hours. Finally, a transparent melamine resin is obtained.

[0034] Among them, the free formaldehyde content is 2.01 and the hydroxymethyl content is 18.8%.

Embodiment 3

[0036] Add 405.4g of aqueous formaldehyde solution to a four-necked flask, adjust the pH to 10.5 with triethanolamine, add 126g of melamine, stir well, place the flask in a water bath and heat to 85°C, and continue the reaction for 4.5 hours after the white solution is completely clear and transparent. Finally, a transparent melamine resin is obtained.

[0037] Among them, the free formaldehyde content is 4.04%, and the hydroxymethyl content is 15.1%.

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