Oponentský posudek Doc. Ing. Ján Sedliačik, Ph.D. Praha, Výhrada k příloze č. 5: Chlorid amónny je legislatívne zakázanou látkou na použitie ako tvrdivo do UF lepidiel, a v praxi sa z tohto dôvodu nepoužíva niekoľko rokov.

Označení v potravinářství - E 510

ParameterUF Solid resin content (%)66 ± 2 Viscosity (mPa.s at 20 °C)400–650 pH at 20 °C7.5–8.7 Densitycca 1300 kg/m³ Hardener (NH 4 Cl) a 15% water solution Wetting agentCarboxymethyl cellulose (CMC) - active substance 63% by weight Retarder of chemical reactionHexamethylenetetramine (C 6 H 12 N 4 ) - 10% to the hardener solution Technical flour20-23 kg/120 kg UF F/U molar ratio<1.0 (<1.0:1) Free formaldehyde< 0.2% Properties and composition of urea–formaldehyde adhesive resin used for manufacturing of plywood panels for interior uses a Percent based on solid content of UF resin Parametervalue Specific pressure MPa a Pressing temperature °C Pressing time60s/1mm b Veneer moistureface: 5-9 %, core 5-12 % Veneer thickness mm Adhesive spread g/m 2 c The pressing conditions for the plywood panels bonded with urea–formaldehyde adhesive resin a MPa for softwood plywood, 1.5 MPa for hardwood plywood b Basic curing time for urea-formaldehyde adhesive is 3 minutes and for the heating of 1 mm veneer thickness, it is 1 minute. The heating of aluminum base, which is inserted to the press with stacked set, adds 1 minute. c It depends on several variable parameters – e.g., nominal veneer thickness and number of layers. With the increasing thickness of veneers the adhesive spread also increases. It also affects the veneer quality and type of plywood. Charakteristika UF lepidla – další dílčí výstup