RU2535226C1 - Method of producing impregnation oligomers - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: described is a method of producing melamine carbamide-formaldehyde oligomers, which includes mixing formalin, brought to the operational hydrogen ion concentration value by a modifier-catalyst based on a salt of a polyfunctional acid, melamine and water, heating the mixture to 90-95°C and cooling upon achieving miscibility of the obtained oligomer with water of 1:1000. Further, the method comprises adding carbamide to the obtained oligomer, cooling the mixture upon achieving miscibility of the oligomer with water of 1:3-1:3.5 and bringing the pH of the mixture to 9.5-10.0. The catalyst-modifier based on a salt of a polyfunctional acid is obtained by mixing sodium or potassium hydroxide, lactic or tartaric acid and water, with the following ratio of components, pts.wt: sodium or potassium hydroxide 13-15, lactic or tartaric acid 16-19, water 68-69.

EFFECT: reduced melamine consumption and low content of free formaldehyde while maintaining processing properties of impregnation oligomers.

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Description

The invention relates to the woodworking industry and can be used in the manufacture of melamine urea formaldehyde oligomers used to impregnate decorative paper in the decoration of wood boards.

A known method of manufacturing an impregnating oligomer, in which the process for producing melamine formaldehyde oligomers proceeds in several stages, each of which is characterized by its own characteristics. The first stage of the reaction is carried out at a pH of 8.1-8.6 and a temperature of 70-80 ° C. After reaching the water number (the water number is characterized by the number of milliliters of water that must be added to 1 ml of the reaction solution in order for it to cloud) 5-10 the reaction solution is cooled to 60 ° C. Reduce the pH to 7.5 and cool the solution to 30-35 ° C. (See. Azarov V.I., Tsvetkov V.E. Technology of binding and polymeric materials: Textbook for universities. - M.: Lesn. Prom-t, 1985. - 216 p .; p. 85).

The closest technological solution is a method for the manufacture of impregnating oligomers, including mixing formalin brought to the working concentration of hydrogen ions, melamine and water, heating the mixture, controlling the miscibility of the resulting oligomer with water, cooling, introducing urea upon reaching the optimum miscibility of the oligomer with water, followed by control over the miscibility of the oligomer with water, after which, when the miscibility of the oligomer with water is reached to the working value, the mixture is cooled, where the formalin is brought to the working value of the concentration of hydrogen ions by a modifier catalyst based on salts of polyfunctional acids, in particular, the sodium salt of citric acid, and after cooling the mixture, the concentration of hydrogen ions in the mixture is adjusted to 9.5-10.0 (p. 1 claims) (See patent RU 2446193 C1, publ. 03/27/2012, 6 pp.).

The disadvantages of the known solutions is the significant consumption of melamine.

The problem solved by the claimed invention is to reduce the consumption of melamine and reduce the content of free formaldehyde while maintaining the technological parameters of the impregnating oligomers.

The solution to this problem is provided by the fact that in the method for the manufacture of impregnating oligomers, comprising mixing formalin brought to the working value of the concentration of hydrogen ions by a modifying catalyst based on a polyfunctional acid salt with a ratio of formalin to a modifying catalyst based on a polyfunctional acid salt, g: 260: 35 -50, respectively, melamine and water, heating the mixture to 90-95 ° C, upon reaching the miscibility of the obtained oligomer with water 1: 1000 cooling, introduction of urea, when achieved and miscibility of the oligomer with water 1: 3-1: 3,5, the mixture is cooled, the concentration of hydrogen ions of the mixture is adjusted with a solution of caustic soda to a pH of 9.5-10.0, while bringing formalin to the working value of hydrogen ions is carried out with a modifier catalyst the basis of the salt of polyfunctional acid obtained by mixing caustic soda or potassium, lactic or tartaric acid and water with a ratio of components, wt. hours:

Caustic Soda or Potassium 13-15 Lactic or tartaric acid 16-19 Water 68-69

The technical essence of the claimed invention lies in the fact that in the synthesis of melamine urea formaldehyde oligomers, alkali, in particular NaOH, is used to neutralize formalin. It is known that in this case the Cannizzaro reaction proceeds, consisting in the restoration of one molecule of one molecule of formaldehyde with the simultaneous oxidation of another:

This reaction leads to a change in the initial molar ratio of formaldehyde to melamine and urea, an increase in the methanol content and a decrease in the pH of the reaction medium during the synthesis. All this, ultimately, leads to a decrease in the quality of veneered boards.

Pretreatment of formalin with a modifier catalyst based on a salt of polyfunctional acid, obtained by mixing sodium hydroxide, citric acid and water in optimal proportions, will prevent the Cannizzaro reaction.

The invention is illustrated by the following examples.

Example No. 1.

By mixing 15 parts by weight of caustic soda, 16 parts by weight of lactic acid and 69 parts by weight of water, we obtain a modifying catalyst based on a polyfunctional acid salt.

Then 260 g of formalin, 35 g of a polyfunctional acid salt-based modifier catalyst are loaded into the reactor, a stirrer is turned on, then 100 g of melamine and 5 g of ethylene glycol are loaded into the reactor. Turn on the heating and heat the reactor to 90-95 ° C. Miscibility with water is monitored every 5 minutes; when miscibility reaches 1: 1000, cooling is turned on. At a temperature of 70-75 ° C, 60 g of urea are charged. Then, when the miscibility of the oligomer with water is 1: 3-1: 3,5, the mixture is cooled to a temperature of 20-30 ° C, adjusted with a 33% sodium hydroxide solution to pH 9.5-10.0.

Comparative properties of the impregnating oligomers are shown in table 1.

Example No. 2.

By mixing 15 parts by weight of caustic soda, 16 parts by weight of lactic acid and 69 parts by weight of water, we obtain a modifying catalyst based on a polyfunctional acid salt.

Then 260 g of formalin, 50 g of a polyfunctional acid salt-based modifier catalyst are loaded into the reactor, a stirrer is turned on, then 150 g of melamine and 5 g of ethylene glycol are loaded into the reactor. Turn on the heating and heat the reactor to 90-95 ° C. Miscibility with water is monitored every 5 minutes; when miscibility reaches 1: 1000, cooling is turned on. At a temperature of 70-75 ° C, 37.5 g of urea are charged. Then, when the miscibility of the oligomer with water is 1: 3-1: 3,5, the mixture is cooled to a temperature of 20-30 ° C, adjusted with a 33% sodium hydroxide solution to pH 9.5-10.0.

Comparative properties of the impregnating oligomers are shown in table 1.

Example No. 3.

By mixing 13 parts by weight of caustic potassium, 19 parts by weight of tartaric acid and 68 parts by weight of water, we obtain a modifying catalyst based on a polyfunctional acid salt.

Then 260 g of formalin are loaded into the reactor, 35 g of a polyfunctional acid salt-based modifier catalyst, a stirrer is turned on, then 125 g of melamine are charged into the reactor. Turn on the heating and heat the reactor to 90-95 ° C. Miscibility with water is monitored every 5 minutes; when miscibility reaches 1: 1000, cooling is turned on. At a temperature of 70-75 ° C, 48 g of urea are charged. Then, when the miscibility of the oligomer with water is 1: 3-1: 3,5, the mixture is cooled to a temperature of 20-30 ° C, adjusted with a 33% sodium hydroxide solution to pH 9.5-10.0.

Comparative properties of the impregnating oligomers are shown in table 1.

Example No. 4.

By mixing 14 parts by weight of caustic potassium, 16 parts by weight of citric acid and 70 parts by weight of water, we obtain a modifying catalyst based on a salt of polyfunctional acid.

Then 260 g of formalin are loaded into the reactor, 50 g of a polyfunctional acid salt-based modifier catalyst, a mixer is turned on, then 150 g of melamine and 5 g of ethylene glycol are loaded into the reactor. Turn on the heating and heat the reactor to 90-95 ° C. Miscibility with water is monitored every 5 minutes; when miscibility reaches 1: 1000, cooling is turned on. At a temperature of 70-75 ° C, 37.5 g of urea are charged. Then, when the miscibility of the oligomer with water is 1: 3-1: 3,5, the mixture is cooled to a temperature of 20-30 ° C, adjusted with a 33% sodium hydroxide solution to pH 9.5-10.0.

Comparative properties of the impregnating oligomers are shown in table 1.

Table 1 Comparative properties of impregnating oligomers Properties of Oligomers Example 1 Example 2 Example 3 Example 4 The closest analogue The solids content at 105 ° C,% 59 58 58 58 58 ± 1 Hydrogen indicator, units pH 9.9 9.9 9.9 9.9 9.0 Conventional viscosity according to B3-4 at 20 ° C 13.8 14.0 13.5 13.7 16.5

Miscibility of resin with water, ml / ml 1: 2.5 1: 2.5 1: 2.5 1: 2.5 1: 2 The content of free formaldehyde,% 0.25 0.21 0.3 0.23 0.5 Penetration time, sec 1,5 1,6 1.4 1,6 5 Resin viability at 5-23 ° C, day 24 thirty 27 25 6-8 Melamine consumption kg / ton 200 300 250 300 400

Thus, we can conclude that the invention allows to reduce the content of free formaldehyde and improve the properties of impregnating oligomers.

Claims (1)

A method of manufacturing melamine carbamide-formaldehyde impregnating oligomers, comprising mixing formalin brought to the working value of the concentration of hydrogen ions by a modifier catalyst based on a polyfunctional acid salt with a ratio of formalin to a modifier catalyst based on a polyfunctional acid salt, g: 260: 35-50, respectively, melamine and water , heating the mixture to 90-95 ° C, when achieving the miscibility of the obtained oligomer with water 1: 1000 cooling, introducing urea, when achieving the miscibility of ol homer with water 1: 3-1: 3,5 the mixture is cooled, the concentration of hydrogen ions of the mixture is adjusted with a solution of caustic soda to a pH of 9.5-10.0, characterized in that the formalin is brought to the working value of hydrogen ions with a modifier catalyst based on salts of polyfunctional acid obtained by mixing caustic soda or potassium, lactic or tartaric acid and water with a ratio of components, parts by weight:
Caustic Soda or Potassium 13-15 Lactic or tartaric acid 16-19 Water 68-69