Liquid lignin composition comprising lignin, water, alkali and urea
A lignin and composition technology, applied in the field of liquid lignin composition, can solve the problem of high viscosity of liquid lignin composition
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Embodiment 1
[0040] Kraft lignin and urea were added to a mixture of water and aqueous sodium hydroxide solution (concentration: 50% by weight NaOH in water). The mixture was stirred for about 5 minutes in a 50 ml plastic container with a lid and then heated in an oven at 55° C. for 1-21 hours. The viscosity of the lignin solution was measured at 25°C using a Brookfield DV-II+LV viscometer. Viscosity values are listed in Table 1.
[0041] Table 1.
[0042]
Embodiment 2
[0044] Lignin-based phenolic resins are prepared for lamination by first premethylolating phenol with formaldehyde before further reaction with lignin and urea added in liquid form as dissolved lignin and urea in an alkaline solution material application.
[0045] Prior to resin synthesis, 104.6 g of kraft lignin (96% solids content), 225 g of water, 40 g of The urea and 23.2g of 50% sodium hydroxide solution were used to prepare the liquid lignin composition. The composition was stirred at room temperature for 90 minutes to ensure complete dissolution of the lignin in the alkaline medium. The liquid lignin composition was poured into a plastic container.
[0046] Lignin-phenol-formaldehyde resins were synthesized at a level of 25% substitution of phenol with lignin. The first step involves prehydroxymethylation of phenol with formaldehyde under basic conditions. In a first step, 304 g of phenol, 304.8 g of formaldehyde (52.5%), 80 g of water and 16 g of 50% alkaline solu...
Embodiment 3
[0052] Lignin-phenol-formaldehyde resins were synthesized for laminate applications at a level of 25% substitution of phenol with lignin.
[0053] In the first step, prior to resin synthesis, 104.5 g of kraft lignin (96% solids content) was mixed at room temperature in a 1 liter glass reactor equipped with overhead stirrer, condenser and temperature control unit by mixing , 187.1 g of water, 22.7 g of urea, 22.7 g of methanol and 27.5 g of 50% sodium hydroxide solution to prepare a liquid lignin composition. The composition was stirred at room temperature of 80°C for 60 minutes to ensure complete dissolution of the lignin in the alkaline medium. Subsequently, the temperature of the liquid lignin composition was lowered to 45°C.
[0054] In a second step, 361 g of phenol and 351.5 of formaldehyde (52.5%) were added to the reaction mixture. The temperature was raised to 90°C. The reaction was allowed to continue for 65 minutes before cooling to room temperature. The reaction...
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