PL111972B1 - Catalyst for polycondensation of urea-formaldehyde resins - Google Patents

Description

and III presented in Table 10, were used after processing to produce 16 mm particleboards. Set IV is a control set in which a standard urea-formaldehyde glue was used according to known methods without the addition of a catalyst according to Wylasic. The particleboards were produced in a laboratory press with dimensions of 40 x 56 cm. Each set was used to spray 10 kg of wood chips. Three boards were formed by hand for each set. The boards were pressed at 11 sec/mm. The press temperature was 200°C and the pressure was 35 kg/cm2. Table 11 gives the average results of the three values. It is obvious that all three sets are equivalent or even better than the control set 4, i.e. without the catalyst according to the invention. Table 10 20 25 30 1 1 Urea-formaldehyde glue 65% Ammonium chloride 15% Hexamethylene tetraamine emulsion 20% Solution 1 Solution 2 1 Solution 3 Water 1 Sets used I 2 1177 0270 0077 0203 0208 — — 0053 | II 3 1177 0270 0077 0203 — 0208 — 0053 III 4 1177 0270 0077 0203 i ¦— . — 0208 0053 | IV 5 | 1385 0270 0077 0203 — — — 0053 1 Table 11 Designations Set I Set II III 1 IV Density kg/m3 712 668 701 731 Conventional bending strength kp/cm2 184 144 204 195 Tensile strength kg/cm2 5.2 , .4.9 6.8 4.4 Swelling after 2 hrs in % 6.0 8.0 5.0 13.1 Swelling after 24 hrs in % 21.4 24.3 17.0 23.2 Similar results can be obtained by replacing the sodium or potassium chloride in the above examples with lithium chloride or with the fluorides, bromides or iodides of sodium, potassium or lithium. Example X. In this example, the following three solutions were prepared: formaldehyde (calculated as 100%) urea sodium chloride water 106 160 27 707 11 16 260 713 183 292 98 427 1000 1000 1000 In solution 1 the ratio of organic (inorganic) parts is 10.0/1.0 while in solution 2, the organic/inorganic ratio is 0.1/1.0. Both samples contain 29% solids. Solution 3 is more concentrated, having 57% solids, with an organic/inorganic ratio of 4.8/1.0. These solutions were used in batches 50 55 60 65 Patent Claims 1. A catalyst for the polycondensation of urea-formaldehyde resins used for bonding water-permeable cellulose particles, which, when used in combination with a known catalyst, increases the rate or degree of polycondensation of the resin while allowing the use of smaller amounts of solid resins without loss of binding capacity, characterized in that it contains a mixture of organic and inorganic components in an amount of 30-150 parts by weight per 100 parts by weight of water, wherein the organic components are formaldehyde and urea or a non-resinous condensation product of formaldehyde and urea, and the inorganic component is a water-soluble alkali metal halide, wherein the weight ratio of organic to inorganic components is 0.1-10.0:1.0 parts by weight. 2. A catalyst according to claim 1, characterized in that it contains formaldehyde and urea as organic components and sodium chloride as inorganic component. LDD Z-d 2 W Pab., Z. 893/1400/81, n. 95+20 copies. Price PLN 45. PL PL PL PL PL PL PL PL PL PL

Claims (1)

1.