Activated lignin composition, a method for the manufacturing thereof and use thereof

Abstract

The present invention relates to an activated lignin composition, its manufacture and its use thereof. It also relates to a resin comprising lignin, its manufacture and use.

Claims

1. A method for making an activated lignin composition, the method comprising the following steps: i) providing a lignin, ii) adding an aqueous dispersant, iii) adding an alkali metal-based catalyst to the lignin, wherein the alkali metal-based catalyst comprises hydroxide, and iv) mixing said components and at the same time reducing the particle size of the lignin, whereby said components are subjected to high shear and flow, thus providing said activated lignin composition, wherein the mixing step includes using a high shear treatment that involves using a mixer with a rotor-stator setup either in batch- or in inline configuration whereby the rotor-stator setup comprises a rotational element which turns at high speeds of above at least about 100 rpm with a stationary element or said setup consists of disc-shaped rotational element comprising saw teeth and/or star-shaped rotational element which turns at high speeds without a stationary element, thus generating high shear and turbulence.

2. A method for the making an activated lignin composition according to claim 1 wherein the high shear treatment involves rotational speeds of above at least about 1,000 rpm.

3. A method for the making an activated lignin composition according to claim 1 wherein said lignin is an alkaline lignin.

4. A method for the making an activated lignin composition according to claim 1 wherein said alkali metal-based catalyst comprises NaOH.

5. A method for the making an activated lignin composition according to claim 1 further comprising the step of adding one or more substituted and/or non-substituted hydroxybenzene compounds before the mixing step.

6. A method for the making an activated lignin composition according to claim 1 wherein the high shear treatment involves rotational speeds of above at least about 10,000 rpm.

Description

FIGURES

(1) FIG. 1 discloses viscosity development.

(2) FIG. 2 discloses thermograms.

(3) FIG. 3 discloses viscosity developments.

EXAMPLES

Example 1

(4) Lignin-phenol-formaldehyde resin was synthesized with a degree of substitution of the phenol with lignin equal to about 50% by weight. In the first step, lignin dispersion was prepared by mixing of 40 g of lignin (96% lignin), 53 g of water and 11.5 g of sodium hydroxide for 30 minutes using a high shear-dispersing equipment, in this case an IKA T25 ULTRA TURRAX High-Speed Homogenizer equipped with a S25 N18G dispersing element in a glass reactor equipped with condenser, overhead stirrer and thermometer. In the 2.sup.nd step, 40 g of phenol (99% Phenol) and 124 g of formaldehyde solution (37% formaldehyde in methanol) were added to the glass reactor. The formaldehyde to phenol ratio was set to 1.8 to facilitate detection of sufficient levels of free monomers. The pH of the solution was adjusted to 11.5 with the addition of an aqueous solution of 45% sodium hydroxide. The reaction mixture was cooked at 80° C. until the viscosity of the reaction mixture reached a certain viscosity. The viscosity was measured at 25° C. using a Brookfield DV-II+ LV viscometer. Viscosity development is illustrated in FIG. 1. After the reaction mixture reached the certain viscosity, it was cooled rapidly to room temperature using a cold water bath. Free monomer content was determined by means of BSTFA- (N,O-Bistrifluoroacetamide) and PFBHA- (o-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride) derivatization for free phenol and free formaldehyde respectively followed by analysis and quantification by GC/MS.

Example 2—Comparative Example

(5) Lignin-phenol-formaldehyde resin was synthesized with a degree of substitution of the phenol with lignin equal to about 50% by weight. 40 g of lignin (96% lignin), 40 g of phenol (99% Phenol), 40 g of water and 124 g of formaldehyde solution (37% formaldehyde in methanol) were combined in a glass reactor equipped with condenser, overhead stirrer and thermometer. The formaldehyde/phenol-ratio was set to 1.8 to facilitate detection of sufficient levels of free monomers. The pH of the solution was adjusted to 11.5 with the addition of an aqueous solution of 45% sodium hydroxide. The reaction mixture was cooked at 80° C. until the viscosity of the reaction mixture reached a certain viscosity. The viscosity was measured at 25° C. as described in Example 1. After the reaction mixture reached the certain viscosity, it was cooled rapidly to room temperature using a cold water bath. Free monomer content was determined by means of BSTFA- (N,O-Bistrifluoroacetamide) and PFBHA- (o-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride) derivatization for free phenol and free formaldehyde respectively followed by analysis and quantification by GC/MS.

(6) Differential scanning calorimetry (DSC) analysis of resins from Example 1 and Example 2 were performed on a Mettler Toledo DSC1 instrument. Prior to analysis, water was removed by freeze-drying to avoid signals from water vaporization which would make it difficult to observe any phase transitions originating from the resins. Approximately 10 mg of sample was weighted in a 100 μl aluminum pan with a punctured lid to enable gas escape. Temperature was ramped from 25° C. to 350° C. at a rate of 4° C./min. The obtained thermograms (see FIG. 2) were further processed in Mettler Toledo STARe software (v. 10.00) by normalization to sample size and baseline correction using the “tangential baseline” type. Surprisingly it was found that viscosity development during synthesis of resin from Example 1 was clearly more advanced than that of resin from Example 2 indicating a much faster reaction.

(7) In addition, the resin prepared in Example 1 contained significantly lower levels of free formaldehyde, displaying increased consumption of formaldehyde during synthesis. This particular feature seen in Example 1 is a clear indication that lignin is activated towards formaldehyde which would also imply that higher lignin substitution levels than what was demonstrated can be achieved. This is also reflected in Table 1.

(8) Furthermore it was found that the resin from Example 1 yielded a more uniform DSC thermogram with only two distinguishable exothermic signals (at 118° C. and 175° C.) while the resin from Comparable Example 1 produced three peaks (111° C., 127° C. and 187° C.). Presence of additional signals in the first exothermic peak is a clear indication of a non-uniform curing behaviour where interfering side-reactions are occurring. Furthermore, the difference between onset and endset temperatures, ΔT is an additional measure of rate of curing. The higher value of ΔT, the lower is rate of curing. It is thus evident that resin from Example 1 had a significant faster rate of curing.

Example 3 (E.1)

(9) Lignin-phenol-formaldehyde resin was synthesized with a degree of substitution of the phenol with lignin equal to about 50% by weight. 42.6 g of lignin (96% lignin), 40 g of phenol (99% Phenol), 37.4 g of water and 110 g of 37% formaldehyde solution were combined in a glass reactor equipped with condenser, overhead stirrer and thermometer. The formaldehyde to phenol ratio was set to 1.6. The pH of the solution was adjusted to 11.5 with the addition of an aqueous solution of 45% sodium hydroxide. The reaction mixture was cooked at 80° C. until the viscosity of the reaction mixture reached a certain viscosity. After the reaction mixture reached the certain viscosity, it was cooled rapidly to room temperature using a cold water bath. Viscosity development is illustrated in FIG. 3.

(10) The final resin was investigated by means of gel time analysis and dynamic light scattering. Gel time was determined using a Techne GT-6 Gelation Timer with a 15 mm plunger which was submerged in the resin and moved in a vertical motion. 25 g of resin was transferred to a tube and heated to 100° C. Gel time was determined automatically as the time at which the resin gelled and the plunger was no longer able to move through the resin. An average of two readings is reported in Table 2.

(11) Dynamic light scattering analysis and particle z-average size was performed using a Malvern Zetasizer Nano ZS instrument 15 min into the reaction and at the end of the reaction when the resin reached the target viscosity. Approximately 50 μl of the resin was dissolved in 12 ml 3M NaCl and shaken until no visible aggregates were present. The sample was scanned 8 times. Reported z-average values, standard deviation and relative standard deviation are listed in Table 3.

Example 4 (E.2)

(12) Lignin-phenol-formaldehyde resin was synthesized with a degree of substitution of the phenol with lignin equal to about 50% by weight. In the first step, lignin dispersion was prepared by mixing of 42.6 g of lignin (96% lignin), 40 g of phenol, 37.4 g of water and 23 g of 45% sodium hydroxide solution for 90 minutes using a high shear-dispersing equipment, in this case an IKA T25 ULTRA TURRAX High-Speed Homogenizer equipped with a S25 N18G dispersing element in a glass reactor equipped with condenser, overhead stirrer and thermometer. In the 2nd step, 110 g of 37% formaldehyde solution were added to the glass reactor and mixed with a propeller stirrer instead of high speed homogenizer. The formaldehyde to phenol ratio was set to 1.6.

(13) The pH of the solution was adjusted to 11.5 with the addition of an aqueous solution of 45% sodium hydroxide. The reaction mixture was cooked at 80° C. until the viscosity of the reaction mixture reached a certain viscosity. The viscosity was measured at 25° C. using a Brookfield DV-II+ LV viscometer. After the reaction mixture reached the certain viscosity, it was cooled rapidly to room temperature using a cold water bath. Viscosity development is illustrated in FIG. 3.

(14) The final resin was investigated by means of gel time analysis and dynamic light scattering as described in Example 2.

Example 5 (E.3)

(15) Lignin-phenol-formaldehyde resin with a degree of substitution of the phenol with lignin equal to about 50% by weight. The formaldehyde to phenol ratio was set to 1.6.

(16) Firstly, 42.6 g of lignin (96% lignin), 40 g of phenol, 37.4 g of water and 110 g of 37% formaldehyde solution were added to the glass reactor and mixed with IKA T25 ULTRA TURRAX High-Speed Homogenizer equipped with a S25 N18G dispersing element. Secondly, 42 g of 45% sodium hydroxide solution was added slowly to reaction mixture to control the exothermic reaction and the pH of the solution was adjusted to 11.5 with the addition of an aqueous solution of 45% sodium hydroxide. The reaction mixture kept under high-intensity mixing using an IKA T25 ULTRA TURRAX High-Speed Homogenizer cooked at 80° C. until the viscosity of the reaction mixture reached a certain viscosity. The viscosity was measured at 25° C. using a Brookfield DV-II+ LV viscometer. After the reaction mixture reached the certain viscosity, it was cooled rapidly to room temperature using a cold water bath. Viscosity development is illustrated in FIG. 3. Gel time is reported in Table 2.

Example 6 (E.4)

(17) Lignin-phenol-formaldehyde resin with a degree of substitution of the phenol with lignin equal to about 50% by weight. The formaldehyde to phenol ratio was set to 1.6.

(18) Firstly, 10.6 g of lignin (96% lignin), 10 g of phenol, 9.1 g of water and 27.6 g of 37% formaldehyde solution were added to a reaction vessel in a formulation workstation. Secondly, 10 g of 45% sodium hydroxide solution was added slowly to reaction mixture to control the exothermic reaction and the pH of the solution was adjusted to 11.5 with the addition of an aqueous solution of 45% sodium hydroxide. The reaction mixture kept under high-intensity mixing using a dissolver disc and cooked at 80° C. until the viscosity of the reaction mixture reached a certain viscosity. The viscosity was measured at 25° C. using a Brookfield DV-II+ LV viscometer. After the reaction mixture reached the certain viscosity, it was cooled rapidly to room temperature using a cold water bath.

Example 7 (E.5)

(19) Lignin-phenol-formaldehyde resin for plywood panel production was cooked in a 5 L glass reactor and mixed with IKA T50 ULTRA TURRAX High-Speed Homogenizer equipped with a S50N-G45F dispersing element. When the reaction mixture reached the certain viscosity, it was cooled rapidly to room temperature using a cold water bath. The included components in the composition of this example were increased fivefold from that of Example 5 above to obtain a lignin-phenol-formaldehyde resin with a degree of substitution of the phenol with lignin equal to about 50% by weight and a formaldehyde to phenol ratio of 1.6.

Example 8 (E.6)

(20) Lignin-phenol-formaldehyde resin containing urea for OSB panel was cooked in a 5 L glass reactor with a degree of substitution of the phenol with lignin equal to about 40% by weight.

(21) Firstly, 337 g of lignin (95% lignin), 484 g of phenol, 396 g of water and 1276 g of 37% formaldehyde solution were added to the glass reactor and mixed with IKA T50 ULTRA TURRAX High-Speed Homogenizer.

(22) Secondly, 231 g of NaOH solution (45%) was added slowly to prevent excessive heat development and giving a pH of 10.2-10.5. The temperature was kept constant at 60° C. for 30 minutes and was then increased to 80° C. The viscosity was measured at 25° C. using a Happier viscometer. Maintain the temperature of the reaction mixture at 80° C. until it reached a viscosity of 400-450 cP.

(23) At this stage, more 165 g of sodium hydroxide solution was added to the mixture giving the pH of 11.3-11.5 and the reaction temperature was lowered to 75° C.

(24) When the desired viscosity (400-450 cP) was achieved, the reaction was cooled down to room temperature (30° C.) and 110 g of urea was added to the reaction mixture. The reaction was stopped when urea was completely mixed.

Example 9 (E.7)

(25) Lignin-phenol-formaldehyde resin containing urea for OSB panel was cooked in a 5 L glass reactor and mixed with pitched blade stirrer with a degree of substitution of the phenol with lignin equal to about 40% by weight.

(26) Firstly, 337 g of lignin (95% lignin), 484 g of phenol, 396 g of water and 1276 g of 37% formaldehyde solution were added to the glass reactor and mixed.

(27) Secondly, 231 g of NaOH solution (45%) was added slowly to prevent excessive heat development and giving a pH of 10.2-10.5. The temperature was kept constant at 60° C. for 30 minutes and was then increased to 80° C. The viscosity was measured at 25° C. using a Happier viscometer. The temperature of the reaction mixture was maintained at 80° C. until it reached a viscosity of 400-450 cP.

(28) At this stage, more 165 g of sodium hydroxide solution was added to the mixture giving the pH of 11.3-11.5 and the reaction temperature was lowered to 75° C.

(29) When the desired viscosity (400-450 cP) was achieved, the reaction was cooled down to room temperature (30° C.) and 110 g of urea was added to the reaction mixture. The reaction was stopped when urea was completely mixed.

Example 10

(30) Veneers were sawn to 550×550 mm.sup.2 size and conditioned in 20° C., 65% RH prior to manufacture. Resin from Example 7 was mixed according to Table 4.

(31) Target resin content was 180 g resin/m.sup.2 with spread on one side. Hot pressing was performed at 140° C. with a pressure of 1 MPa, with repeated release of steam during the first 4 minutes. The total pressing time was 10 minutes. After hot-pressing, the boards were cooled between two aluminium plates at room temperature.

(32) Prior to evaluation all samples were conditioned according to EN636 class 3 test method. Shear strength was evaluated according to EN314 test method. Average data from 3 boards is presented in Table 5.

Example 11

(33) Spruce boards were cut into 190 mm long pieces and strands were manufactured in a disk flaker and sieved. The impregnation of the wood strands was performed in a rotating drum batch using the resin from Example 8 or 9 which was diluted with water to reach a specific viscosity. The impregnated OSB strands were spread and hot-pressed at 160° C. for a total pressing time of 10 min to achieve boards measuring 540×540 mm.sup.2.

(34) After hot-pressing, the boards were cooled between two aluminium plates at room temperature. Prior to evaluation all samples were conditioned at 20° C. and 65% RH. Internal bonding was evaluated before and after cyclic test conditions specified in V313 standard. Average data from 3 boards is presented in Table 6.

(35) TABLE-US-00001 TABLE 1 Free monomer content of resins prepared in Examples 1 and 2. Free Free Phenol Formaldehyde Sample (% w/w) (% w/w) Example 1 0.0 1.6 Comparable Example 2 0.0 6.2

(36) TABLE-US-00002 TABLE 2 Gel time Sample Gel time (min) Resin from Example 3 76 Resin from Example 4 45 Resin from Example 5 46

(37) TABLE-US-00003 TABLE 3 Dynamic light scattering data Resin from Example 2 After 15 min Z-Average (d .Math. nm) 260 STD 94 RSD (%) 36 At target viscosity Z-Average (d .Math. nm) 9500 STD 1400 RSD (%) 15 Resin from Example 4 After 15 min Z-Average (d .Math. nm) 250 STD 34 RSD (%) 13 At target viscosity Z-Average (d .Math. nm) 4100 STD 560 RSD (%) 14

(38) TABLE-US-00004 TABLE 4 Plywood board composition Component Amount [%] Resin from Example 7 77.5 Water 8 Olive seed flour 10.7 NaOH (35%) 3.8

(39) TABLE-US-00005 TABLE 5 Plywood board shear strength according to EN314 standard Shear Strength (MPa) Board # Average STD Median Average 1.51 0.25 1.50

(40) TABLE-US-00006 TABLE 6 OSB board densities, internal bond and residual strength after conditioning and aging according to V313 standard. After conditioning After aging according to (20° C., 65% RH) V313 standard Density Internal Bond Internal Bond Residual Board # Average Average STD AVERAGE STD Strength Board based on resin from Example 8 Average 707 0.76 0.13 0.51 0.06 68% of 3 boards STD 16 0.02 0.06 Board based on resin from Example 9 Average 691 0.63 0.10 0.41 0.07 65% of 3 boards STD 18 0.03 — 0.03 — —

(41) Various embodiments of the present invention have been described above but a person skilled in the art realizes further minor alterations, which would fall into the scope of the present invention. The breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents. For example, any of the above-noted compositions or methods may be combined with other known methods. Other aspects, advantages and modifications within the scope of the invention will be apparent to those skilled in the art to which the invention pertains.