SU104644A1 - The method of obtaining artificial resin - Google Patents

Description

There are methods for producing urea-forms of aldehyde resins combined with furfural. In all of these processes, urea and furfural are initially condensed, and then the products obtained are condensed additionally with formaldehyde.

The RESINS obtained by these methods were proposed, in particular, for the production of adhesives, but the water resistance, mechanical strength and elasticity of the adhesive compositions were not high enough.

The proposed method of obtaining a urea - formaldehyde resin combined with furfural is characterized in that urea and formaldehyde are initially condensed, and then the products obtained are condensed with furfural. A change in the order of condensation of the components leads to a significant change in the reaction chemistry and. Consequently, the quality of the products. As a result of this condensation method, a significant amount of methylol groups is retained in the resin, as a result of which the water resistance, mechanical strength and elasticity of

Resin glue and coupling compositions.

Example 1 - resin synthesis. 180 g of urea (1 mol) is condensed from 486 g of 37% formalin (2 mol) for 30 minutes at a temperature of 92–95 in the presence of

1N r-ra NaOH (18 ° about the weight of urea). Then 36 g of furfural (0.3 mol) is introduced into the reaction mixture and the condensation continues at the same temperature for another 15 min. The mixture is then o.closed up to 25-30, 25% ammonia water is introduced (18% by weight of urea) and the mixture is subjected to a vacuum drier until K.P. 1.49-L50.

Resin characteristic

1. Formaldehyde content

2 2.5%.

2. The content of methyl groups is 18-20%.

3.K. R. 1.49 - 1.50.

4. Dissolved in water in any ratios.

Example 2. Preparation of an adhesive composition for gluing wood. .

Formulation L 1. Adhesive adhesive. - 100 wt. hours, 10% aqueous solution of orthophosphoric acid - 15 - 20 weight. h, diatoms - 20

weight. h. (or 10 wt. h. a / tumeniev dust).

Viability k.: 1eevogo composition from 3 to 5 hours.

Formulation number 2. Adhesive resin - 100 wt. hours, 10% aqueous solution of oxalic acid 20 - 25 weight. am (or 4 wt. am of ammonium chloride), wood flour - 6 - 8 wt. h

The viability of the adhesive composition 4 - 6 hours.

The adhesive composition is applied with an ovarian layer to both glued wooden surfaces and maintained at a pressure of 2 to 2.5 kg / cm for 8 to 10 hours at room temperature.

Glue seam provides a tensile strength of not less than 130 kg / cm

Example 3. Preparation of coupling compositions.

A 10 to 15% aqueous resin solution is prepared and 1 to 2% ammonium chloride is added to it, based on 100% resin.

The viability of the composition of at least 24 hours.

Shrinkage of alkaline tissue - no more than 2%.

Pr; edmet invention

The method of obtaining an artificial resin based on urea and formaldehyde combined with furfural, characterized in that, in order to obtain an adhesive resin with improved indicators of water resistance, mechanical strength and elasticity, urea is condensed in the initial stage with formaldehyde in the presence of bases and the resulting products the condensations in the final stage are combined with furfural.