Preparation of Two-Component Polyurethane Coatings from Bleached Liquefied Wood

Abstract

Liquefied wood-based polyurethane wood coatings of an aesthetically acceptable light colour were prepared and characterised. Liquefied black poplar wood was obtained by solvolysis in a polyethylene glycol/glycerol mixture, and it was bleached with hydrogen peroxide. The bleaching treatment converted liquefied wood from a dark brown to a yellowish product. Polyurethane films were prepared by the curing of liquefied wood with polymeric diphenylmethane diisocyanate or trimethylolpropane toluene diisocyanate prepolymer (TMP/TDI) isocyanate-type hardeners. It was found that the selected properties of the films prepared from the bleached liquefied wood were, in general, equivalent to those prepared from unbleached liquefied wood. The mechanical properties of the films obtained with the TMP/TDI curing agent were acceptable for wood coating applications. The initial poor resistance of the films to water and ethanol was substantially improved by the addition of n-octyltriethoxysilane to the liquefied wood prior to the preparation of the polyurethane coatings; the hardness of the films also increased.

Polyurethane Coatings on Hardwood and Softwood Surfaces: Their Resistance to Household Liquids as an Educational Case Study

“…The results of the work of Cheumani-Yona et al (2015) show that the resistance of the coating film is affected by the type of curing agent used, which can reduce or increase the resistance of the coating film. In our case, the curing agent used was supplied with our coating material.…”

Uporaba naravnih olj za površinsko zaščito lesa navadne bukve

“…V barvnem sistemu CIELAB, L* predstavlja svetlost vzorca in variira od 0 (črna) do 100 (bela); a* predstavlja zeleno (-a*) do rdeče (+ a*) os in b* je modra (-b*) do rumena (+ b*) os (Cheumani-Yona et al, 2015). V raziskavi smo spremljali spremembo barve iz dveh razlogov: z estetskega vidika je zaže-leno, da se barva oljenega lesa določen čas po končanem oljenju ne spreminja več.…”

Determination of color-changing effects of bleaching chemicals on some heat-treated woods

“…At the end of the application, the highest color change value was obtained on the pine, beech and chestnut surfaces with the S4 (NaSiO 3 + H 2 O 2 ) solution and on the oak surfaces with the S1 solution. Cheumani-Yona et al [20] carried out the bleaching of liquefied black poplar wood with hydrogen peroxide. After the bleaching process, they found a remarkable increase in the color parameters L* a* b* and ΔE*.…”