Blocked melamine–urea–formaldehyde resins and their usage in agglomerated cork panels

Abstract

Caprolactam and o‐p‐toluenesulfonamide are tested as chain‐growth blockers for melamine–urea–formaldehyde (MUF) resins, in an attempt to reduce the crosslinking density of the cured resin and hence improve its flexibility. Agglomerated cork panels, for which flexibility is a technical demand, were produced with the modified resins and tested. The blockers were added at three different steps in the synthesis process: methylolation, condensation, and at the end of the synthesis. Besides evaluation of standard properties, resins were characterized using gel permeation chromatography and Fourier transform infrared. Blocked resins showed better storage stability and improved water tolerance, especially when caprolactam was employed. When used as binders in agglomerated cork panels, the blocked resins allowed for significantly better flexibility, evaluated in terms of mandrel bending test. The tensile resistance of the panels remained well within the desired limits for this type of material. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46663.

The comparative study of biocomposites based on hydrochar and chitosan‐modified urea‐formaldehyde resins

“…[ 63 ] The peak at 1340 cm −1 can be attributed to the CN vibration of the methylene bond. [ 64–66 ] This indicates that the introduced chitosan during the synthesis causes the formation of ethylene bonds while simultaneously reducing the methylene ether bond. [ 61 ]…”

“…[63] The peak at 1340 cm À1 can be attributed to the C N vibration of the methylene bond. [64][65][66] This indicates that the introduced chitosan during the synthesis causes the formation of ethylene bonds while simultaneously reducing the methylene ether bond. [61] The peaks at 1232-1238 cm À1 , for both modified UF resins, originated from C N stretching vibrations of amide II [67] and C C O asymmetrical stretching vibration of ester groups.…”

Morphology of wood degradation and flame retardants wood coating technology: an overview

“…It also has good fire resistance properties (Xie et al 2016). Melamine-urea-formaldehyde resin is widely utilized in wood coating industries due to its low cost, better performance and maximum reactivity (Cremonini et al 1996; Yano et al 2000; Stöckel et al 2010; Antunes et al 2018). Melamine-formaldehyde resins were used to make agglomerated cork boards which have good mechanical resistance and moisture resistance (Antunes et al 2018).…”

“…Melamine-urea-formaldehyde resin is widely utilized in wood coating industries due to its low cost, better performance and maximum reactivity (Cremonini et al 1996; Yano et al 2000; Stöckel et al 2010; Antunes et al 2018). Melamine-formaldehyde resins were used to make agglomerated cork boards which have good mechanical resistance and moisture resistance (Antunes et al 2018). Furthermore, melamine-urea-formaldehyde resin contains nitrogen elements that act as a flame-retardant element by generating non-flammable gases, such as ammonia and nitrogen in a fire and further prevent the transfer of oxygen.…”

Synthesis of blocked waterborne polyurethane with 3,5‐dimethylpyrazole for industrial application in digital inkjet printing

“…The reactions are reversible and once the BWPUs are heated at a certain temperature, it will be deblocked to regenerate blocking agents and NCO groups which are supposed to crosslink with reactive hydrogen functional group of fiber in order to form thermally stable bonds and improve fastness . The commonly used blocking agents are caprolactam, 2‐butanone oxime, and sodium bisulfite . The caprolactam and 2‐butanone oxime deblock at 170 and 150 °C, respectively.…”