Preparation of lignins

The addition of phenol-formaldehyde precondensate to lignin or methylolated lignin has been known as a way to introduce phenolic reactivity into lignin, and this is usually applied to the preparation of lignin-based... 

Examples where the phenolic hydroxy groups were utilized include the preparation of lignin epoxies by reaction with epichlorohydrin (2), esterifications with bis-acid chlorides (3) and cyanuric chloride (4), and polymerization with aziridines (5). 

Terashima, N., Atalla, R. H., Ralph, S. A., Landucci, L. L., Lapierre, C., and Monties, B., 1996, New preparations of lignin polymer models under conditions that approximate cell well lignification I. Synthesis of novel lignin polymer models and their structural characterization by 13C NMR., Holzforsch. 49 521-527. 

Kubo, S. Ishikawa, N. Uraki, Y. Sano, Y. Preparation of lignin fibers from softwood acetic acid lignin—relationship between fusibility and the chemical structure of lignin. Mokuzai Gakkaishi 1997, 43 (8), 655-662. 

Itoh, K. Preparation of Lignin Fiber. Japan Patent H1239114, 1989. 

A cooperation agreement was made in 1973 between DDS-RO and the Finnish Pulp and Paper Research Institute with the aim to develop products and processes on the basis of membrane filtration of effluents from the pulp and paper Industry. The cooperation with Dr. Kaj Forss section at FPPRI has been very successful. For instance, through an extensive development program UF has been found to be a feasible tool for the preparation of lignin for the Karatex ( ) plywood binder. This adhesive, which is made from ultrafiltered spent sulfite liquor (SSL) or kraft black liquor (KBL), can be used for partial replacement of the much more expensive petroleum based phenol-formaldehyde resin in plywood and other wooden boards. 

New preparations of lignin polymer models under conditions that approximate cell wall lignification. II. Structural characterization of the models by thioacidolysis. Holrforschung 50(1), 9-14. 

M Lawoko, G Henriksson, G Gellerstedt. New method for quantitative preparation of lignin-carbohydrate complex from unbleached softwood kraft pulp Lignin polysaccharide networks I. Holrforschung 57 69-74, 2003. 

Fig. 15 Preparation of lignin-based rigid PU foams HL-1 New Zealand HL-2 Russia (Archangelsk plant) HL-2 Russia (Lobinsky plant) HL-4 Russia (Kirovsky plant)...

LSD and MLD mixtures were reacted with MDI that was used for the preparation of lignin- and molasses- based PU composites filled with wood powder. For the preparation of the above composites, first wood powder was added to the mixture of LSD and MLD. Then the mixture was stirred at room temperature, MDI was added, poured into a stainless steel frame, and pressed under pressure of ca. 20 MPa at 120°C for 2 hr. In the above biocomposites, wood powder contents were changed from 50 to 90%. LSD and MLD mixture ratios were changed as follows 0/100, 20/80,40/60, 50/50, 60/40,80/20, and 100/0. 

The following methods are examples of preparation of lignin-based PU s. Prior to obtaining PU s, KL, LS, AL and SL were dissolved in polyols. In order to prepare PU foams, the polyol solution was mixed first with surfactant (silicone oil) and a catalyst, then MDI was added. This mixture was vigorously stirred with a trace amount of water, which was added as a foaming agent. In the above processes, the NCO/OH ratio was decided according to the required physical properties of prepared PU foams. 

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