SU724531A1 - Method of preparing ureamelaminoformaldehyde resin - Google Patents

Description

I

. The invention relates to the synthesis of carbamide resins and can be used for the production of sioteticheskikh adhesives used in the woodworking industry, construction and other areas.

A known method for producing urea melamine formaldehyde resin by condensation by heating urea, melamine and formal 5; 1 dehydate followed by concentration of l.

However, a resin with non-satisfactory properties is obtained.

The purpose of the invention is to improve the properties of the resin

The goal is achieved by the fact that urea, melamine formaldehyde and covdensation at pH 2.5-4 and QS-IOOV. with a molar ratio of the starting components of 0.52; O, GO7..0.063: 1.3-4.

Example. Production of urea-melamine-formaldehyde resin at the optimum values of the Parameters of the method of phi composition, parts by weight:

Formalin, 4O.- | 1st water-, ny solution2 OS

Urea56

Melamine4

In the reactor, equipped with a thermostatic device, a reflux condenser and a stirrer, load 200 weight.h. (2.6 mol) 4O ° i-Horo formalin solution, 56 parts by weight (0.9 mol) of urea and 4 weight.h. (0, OZ) mole is melamine, pH of the mixture is 4.0. The mixture is heated before, and with vigorous stirring, paps shifts occur. Initially, when found, the reaction mixture becomes transparent, since urea to melamine dissolves in formalin to form methyl derivatives, then the reaction mixture becomes slightly cloudy and remains until the end of the synthesis, while methyl derivatives interact with each other and with each other the formation of methylene and partially ether bridges between methylol derivatives of melamvva and urea. Polycondensation lasts 30 min. After this time, heating is stopped, the pH of the resin is 4.0. Next, conduct; neutralization of the resin by adding a solution of sodium bicarbo kata to pH 7.0. Neutralization of the resin is necessary to avoid corrosion, which is possible with respect to the low melamine content in pmol. The resulting aqueous resin is characterized by the following n6CaSyoHsCoC residue,% Specific gravity, g / cm Viscosity using an OT-4 viscometer, with Life carrying the capacity of a month. The content of free formaldehyde,% The aqueous resin is subjected to evaporation, which can be carried out in. reactor. Evaporation is carried out at tipH + 100 ° C, with constant stirring at 1.4 times the volume of the aqueous resin (i.e. the distilled water is equal to 1/4 the volume of the water resin). During the evaporation, under the action of temperature, an octant depth p H1I condensation occurs with the formation of the spatial structure of the polymer. The resulting resin is transparent, light-colored, and has a pale color. The main properties of CM, .- - ---- .-., ...-,: --- .- ..;: ..-,: .-, ... are shown in the table. After 1 month a sample of resin diluted with two times the amount of water did not precipitate, i.e. well dissolved. Example 2. Preparation of urea-melamine-formaldehyde resin at minimum values of X parameters using the composition, parts by weight: Formalin, 409% aqueous solution 100 (1.3 mol) Urea 32 (0.5 mol) Melamine1 (0.007 mol To the reactor is charged 100 parts by weight of a 40% solution of ps raspberry, 32 parts by weight of urea and 1 wt. H; melamine, pH of the mixture is 2.0. The mixture is heated to +98 ° C and when intensive quenching occurs, the PuyCondensation lasts 33 minutes. time, the heating is stopped, the pH of the resin is 4.5. Next, the resin is neutralized by adding soda-bicarb nat natri.

724531 P 7.1. The resulting aqueous resin is characterized by the following indicators:: Dry residue,% 46.4 Specific weight, g / cm1,172 Viscosity by VZ-4 viscometer, s1,200 Viability, months. Content of free formaldehyde,% 1.0 The aqueous resin is evaporated at + 85 ° С, at 1/4 of the volume of the aqueous resin. The resulting resin is transparent, light yellow in color. The resin property is shown in the table. After 1 month The sample of the resin, azvedenna dvukr agnyi vzh fever, voi, does not precipitate. PRI me R 3, Preparation of a urea-amino-formaldehyde resin at the maximum values of the parameters of the process, according to the composition, by weight.h .; FbrmanLin, 4P5.-Hb1I aqueous solution 300 (4 mol) 120 (2 mol) L1 uchevina 8 (0.063 mol) Melamine AOR is added to the reactor, parts by weight 40 ° i formalin solution, 120 weight.h. urea and 8 weight.h. melamine, RP mixture 3, O. The mixture is heated to + 95 ° C with vigorous movement for 35 minutes. After this time has elapsed, the heating is stopped, the pH of the resin is 5. Next, the resin is neutralized by adding sodium bicarbonate to a pH of 7.2. The resulting aqueous resin is characterized by the following indicators: 46.9 1Д77 Dry residue, Specific weight, g / cm 1.232 Viscosity according to VZ-4, with 1.5 Viability, months. . The content of the free form of aldehyde,% 1.1 The aqueous resin is evaporated at + 8 ° C, With constant stirring at 1/4 of the volume of the aqueous Resin. Polunyun resin is transparent, light yellow in color. The properties of the resin are shown in the table. After 1 month, a sample of the resin diluted with two times the amount of water did not precipitate.

Claims (1)

The invention of the method for producing urea-1-amino-formaldehyde resin by condensation by heating urea, melamine and formaldehyde, followed by concentration, characterized in that, in order to improve the properties of the resin, urea, melamine and formaldehyde are condensed at pI 2.5-4 and 95-10 ° C with the molar ratio of the starting components is 0.5-2: 0.007-0.063: 1 ,. Sources of information taken into account in the examination 1, Austrian Patent Nv 334627, cl. C 08 G 12/38, published January 25, 1997