Open AccessINFLUENCE OF MODIFIERS ON THE CURING TIME OF THE PHENOL FORMALDEHYDE BINDER FOR PRESSING PANELS AT LOW TEMPERATURE MODE
Author(s) -
Tat'yana Vahnina,
А. А. Федотов,
Andrey Titunin,
Irina Susoeva
Publication year - 2020
Publication title -
lesotehničeskij žurnal
Language(s) - English
Resource type - Journals
ISSN - 2222-7962
DOI - 10.34220/issn.2222-7962/2019.4/11
Subject(s) - curing (chemistry) , formaldehyde , phenol , materials science , sulfate , phenol formaldehyde resin , chloride , chemistry , composite material , pulp and paper industry , chemical engineering , organic chemistry , metallurgy , engineering
Volumes of plywood production with increased water resistance for indoor and outdoor use (FSF brand) are increasing in Russia. The demand for it in the country and in the world continues to grow. The phenol-formaldehyde oligomer during the curing process passes through the stages of resol, resitol and resite. Ensuring long-term water resistance of plywood is possible only if the resite stage is reached and the solidified phenol-formaldehyde resin (FFR) reaches non-melting and insoluble state. The problem is that the industrial process of FSF plywood pressing is carried out in the rezitol temperature range. In literature, there are conflicting data on the temperature ranges of the stages of the FSF polycondensation process. The authors have proposed to operate with scientific data on the temperature ranges of FFR curing, confirmed by the results of spectroscopic studies. It is necessary to develop phenol-formaldehyde binder compositions capable of curing to the resite stage at lower pressing temperatures than unmodified FSF to ensure the necessary operational characteristics of FSF plywood. In this study, a number of modifiers have been proposed that potentially reduce the time it takes to press plywood at low temperatures. The gelatinization time of the phenol-formaldehyde binder based on the SFZh-3014 resin (according to 20907-2016 State Standard) and modifying additives (hydrogen peroxide, eight-water zinc sulfate, ammonium alum, anhydrous magnesium chloride, six-water iron chloride, six-water aluminum chloride, aluminum dimethyl sulfate, dimethyl glyoximate, and sulfate, sulfosalicylic two-water acid) have been determined. A study of the gelatinization process in the presence of a large number of modifying additives (more than 1.5%) revealed a significant deterioration in the spreadability of the binder. Therefore, it is recommended to use FFR curing accelerators in the amount not exceeding 1-1.5%.