SU1116039A1 - Method of obtaining carbamideformaldehyde resin - Google Patents

Abstract

METHOD FOR OBTAINING CARBAMVODOFORMALDEGVDNYY RESIN with a finite molar ratio of urea. and formaldehyde 1: 1.3 by condensation of urea and formaldehyde at pH 7.5-4.2 with subsequent neutralization by vacuum drying, condensation in the presence of an additional portion of urea and cooling the finished resin, characterized in that, in order to increase the stickiness of the resin and the quality of the glued wood materials, at the stage of decondensation, casein is additionally introduced in a mixture with water and urea, taken in an amount of 0.8–8% of an additional portion of urea with a mass ratio of casein, urea and water, respectively, 0.8: 1: 1. with

Description

The invention relates to the production of urea-formaldehyde resins for gluing wood materials. A known method for producing carbs of pre-formaldehyde resin with a final molar ratio of urea to formaldehyde is 1; 1.6 by condensing the reaction mixture of formalin and carbamide in neutral, slightly alkaline, then in {medium media, vacuum drying by condensation with an additional portion of urea and cooling the finished resin tl 3. However, the resin obtained by this method is not sufficiently sticky when gluing wood materials and is toxic. The closest effect to be achieved is a method of obtaining a urea-formaldehyde resin with a final molar ratio of carbs and formaldehyde of 1: 1.3, condensation of urea and formaldehyde at pH 7.5-4.2, followed by neutralization, vacuum drying, condensation in the presence of an additional portion of urea and cooling the finished resin 2}. When using resins obtained by this method, they are not sufficiently sticky, which leads to a violation of the solidity of veneer packages, an increase in the thickness of the package and the detachment of individual sheets are observed. The purpose of the invention is to increase the stickiness of the resin and the quality of the glued wood materials. The goal is achieved by agreeing with the method for producing a urea-formaldehyde resin with a final molar ratio of urea to formaldehyde of 1: 1.3 by condensation of urea and formaldehyde at pH 7.5-4.2 with subsequent neutralization by vacuum drying, condensation in the presence of an additional portion of urea and cooling the finished resin, at the stage d of condensation of vvdt casein s mixtures with water and urea, taken in an amount of 0.8-8% of the additional pore of urea at a mass ratio of casein, urea and water, respectively, 0.8: 1: one. A mixture of casein, carbamide and water is prepared separately by heating at 50-70 ° C and constant stirring for 30 minutes until a homogeneous syrupy solution is formed. To test the proposed resin, plywood was made from birch veneer sheets 1.5 mm thick and 400-400 mm in size. On the basis of the synthesized resins, an adhesive of the following composition was prepared, mac.ch .: resin 100, hardener (ammonium chloride) 1. Consumption of glue 100-110 g / m of veneer surface. The glue was applied by glue rollers with smooth metal drums. Packages are assembled in the usual way: a 3-ply bag was assembled, out of four 3-ply bags one common bag was assembled, which was compressed in a cold press (temperature 20 ± 2 ° C) at a pressure of 10-12 kgf / cm for 7 minutes . In tab. Table 1 lists the formulation and conditions for resin production, in Table. 2 data on the properties of the obtained image of resin. The pressed packages were further subjected to hot pressing at 125130 s and 20 kgf / cm for 5.5 min. After pressing, 6 samples were cut out from each sheet of plywood according to GOST 9620-72 and placed in a bath with water for 24 hours. The tensile strength of three-layer plywood when splicing on the adhesive layer was determined according to GOST 9624-72. In tab. 3 shows the results of tests, plywood, made on the basis of resins, obtained by the known and proposed methods. Thus, the above data confirms the possibility of obtaining resins with high stickiness and high adhesive properties. The use of resins obtained by the inventive method makes it possible to improve the quality of glued materials, for example, plywood, especially when glued. Her research institutes with pre-cold pressing.

Table 1

Continued table. one

Duration, min 90

Refractive index 1,450

PH 7.0

Decondensation

Loading

Amount ,, g of 540 carbamide

Solution. ProdolzhitelNIN

carbamide i min

Loading

mods

supplements

(mixture

casein

carbamide

and water)

Quantity, g

including casein

Urea

Water

Gearing, min

Temperature with

Duration, min

Temperature with

95

95

1,451

1.452 7.0 7.0.

535.8

518.6

497.2

ten

ten

ten

60.0

120

12.0

3.4

17

34

4.3 (0.8%) 2L, 5 (4% / 43 (8% from 540 g from 540 g of urea) urea)

4.3

43

21.5

Claims (1)

D METHOD FOR PRODUCING A CARBAMIDE-FORMAL DEHEAD RESIN with a finite molar ratio of carbamide. and formaldehyde 1: 1.3 by condensation of urea and formaldehyde at pH 7.5-4.2, followed by neutralization by vacuum drying, post-condensation in the presence of an additional portion of urea and cooling of the finished resin, characterized in that, in order to increase the stickiness of the resin and the quality of glued wood materials, at the stage of decondensation, casein is additionally introduced in a mixture with water and urea, taken in an amount of 0.8-8% of an additional portion of urea with a mass ratio of casein, urea and water, respectively 0.8: 1: 1.