Binder composition comprising poly(amino acid)s for fiber composite articles

Abstract

The present invention relates to a binder composition comprising component A comprising polymer(s) A1 and optionally component B comprising component B1 which is selected from the group consisting of a mono-saccharide s, disaccharides, hydroxyacetone, glycolaldehyde and mixtures thereof, wherein polymer(s) A1 comprises at least 70 wt.-% poly(amino acid)s based on the total weight of the polymers) A1 and has (have) a total weight average molecular weight M.sub.w,total of 800 g/mol to 10.000 g/mol, wherein the binder composition comprises 60 to 100 wt.-% polymer(s) A1, and 0 to 40 wt.-% component B1, based on the total weight of the sum of polymer(s) A1 and component B1, wherein the weight amounts of the polymer(s) A1 and component B1 are selected such that the total weight of the sum of polymer(s) A1 and component B1 is 100 wt.-%.

Claims

1. Use of a binder composition comprising component A comprising polymer(s) A1 and optionally component B comprising component B1 which is selected from the group consisting of monosaccharides, 5 disaccharides, hydroxyacetone, glycolaldehyde and mixtures thereof, wherein polymer(s) A1 consist(s) of polylysine(s) and has(have) a total weight average molecular weight M.sub.w, total of 800 g/mol to 10,000 g/mol, wherein the binder composition comprises 80 to 100 wt.-% polymer(s) A1, and 0 to 20 wt.-% component B1, based on the total weight of the sum of polymer(s) A1 and component B1, wherein the weight amounts of the polymer(s) A1 and component B1 are selected such that the total weight of the sum of polymer(s) A1 and component B1 is 100 wt.-%, for the preparation of a lignocellulosic fiber board, wherein 3 to 15 wt-% polymer(s) A1 and component B1 in total based on the total oven-dry weight of the lignocellulosic fibers are used for the preparation of the lignocellulosic composite article.

2. Use according to claim 1, wherein component B1 is selected from the group consisting of hydroxyacetone, 1,3-dihydroxyacetone, xylose, fructose, glucose, mannose, saccharose and mixtures thereof.

3. Use according to claim 1, wherein no compound B is included.

4. Use of a reacted Binder composition obtainable or obtained by reacting the binder components A and B and lignocellulosic fibers or reacting component A and lignocellulosic fibers as defined in claim 1, for the preparation of a lignocellulosic fiber board.

5. Use of a composition kit comprising the binder composition as defined in claim 1, wherein component A and component B are stored separately, for the preparation of a lignocellulosic fiber board.

6. A lignocellulosic fiber board comprising a plurality of lignocellulosic fibers, and a binder composition as defined claim 1, wherein 3 to 15 wt-% polymer(s) A1 and component B1 in total based on the total oven-dry weight of the lignocellulosic fibers are used for the preparation of the lignocellulosic composite article.

7. The lignocellulosic fiber board according to claim 6, having a thickness of 1.5 to 5 mm.

8. The lignocellulosic fiber board according to claim 6, having an internal bond strength of more than 0.8 N/mm.sup.2.

9. A process for the batchwise or continuous production of lignocellulosic fiber boards which are multi-layered lignocellulose-based fiber boards with a core and with at least one upper and one lower surface layer, comprising the following steps: a) mixing of the lignocellulosic fibers with a binder composition for each layer, wherein the mixture for at least one layer comprises the binder composition as defined in claim 1, b) layer-by-layer scattering of the mixtures of the individual layers to form a mat, c) pressing the mat to a board at a temperature of 80 to 300? C. and at a pressure of 1 to 100 bar wherein 3 to 15 wt.-% polymer(s) A1 and component B1 in total based on the total 20 oven-dry weight of the lignocellulosic fibers, are used for the preparation of the lignocellulose-based fiber boards.

10. A process for the batchwise or continuous production of single layered lignocellulosic fiber boards comprising the following steps: a) mixing of the lignocellulosic fibers with a binder composition, wherein the mixture comprises the binder composition as defined in claim 1, b) scattering of the mixtures to form a mat, c) pressing the mat to a board at a temperature of 80 to 300? C. and at a pressure of 1 to 100 bar or c) pressing the mat to a board at a temperature of 80 to 200? C. and at a pressure of 0.1 to 100 bar, wherein a high-frequency electrical field is applied during pressing until 80 to 200? C. is reached in the center of the mat wherein 3 to 15 wt.-% polymer(s) A1 and component B1 in total based on the total oven-dry weight of the lignocellulosic fibers, are 5 used for the preparation of the lignocellulose-based fiber boards.

11. A process for the batchwise or continuous production of lignocellulosic fiber boards which are multi-layered lignocellulose-based fiber boards with a core and with at least one upper and one lower surface layer, comprising the following steps: a) mixing of the lignocellulosic fibers with a binder composition for each layer, wherein the mixture for at least one layer comprises the binder composition as defined in claim 1, b) layer-by-layer scattering of the mixtures of the individual layers to form a mat, c) pressing the mat to a board at a temperature of 80 to 300? C. and at a pressure of 1 to 100 bar wherein 3 to 15 wt.-% polymer(s) A1 and component B1 in total based on the total 20 oven-dry weight of the lignocellulosic fibers, are used for the preparation of the lignocellulose-based fiber boards, wherein both components A and B of the binder composition as defined in claim 1 are added to the lignocellulosic pieces in step a) either a1) separately from one another or a2) as a mixture.

12. The process according to claim 9, wherein the lignocellulosic fibers are prepared from wood.

13. The process according to claim 10, wherein the boards obtained in step c) or step c) have an internal bond strength of more than 0.8 N/mm.sup.2.

Description

BRIEF DESCRIPTION OF FIGURE

(1) FIG. 1: HDF boards, 4 mm, binder amount 6 wt.-% (solid/dry wood), press time factor=10 sec/mm, ratio of polylysine in binder is defined as weight ratio of Polylysine-4 (solids) to the sum of Polylysine-4 (solids) and glucose (solids). FIGURE shows the influence of the amount of polylysine on the in internal bond.

MATERIALS

(2) Hydroxyaceton, Alfa Aesar Glucose monohydrate, Sigma Aldrich, Spain L-Lysine solution (50% in water), ADM animal nutrition, USA Spruce wood chips and fibers from Germany, Institut f?r Holztechnologie Dresden

(3) Spruce Wood Chips

(4) The chips were produced in a disc chipper. Spruce trunk sections (length 250 mm) from Germany were pressed with the long side against a rotating steel disc, into which radially and evenly distributed knife boxes are inserted, each of which consists of a radially arranged cutting knife and several scoring knives positioned at right angles to it. The cutting knife separates the chip from the round wood and the scoring knives simultaneously limit the chip length. Afterwards the produced chips are collected in a bunker and from there they are transported to a cross beater mill (with sieve insert) for re-shredding with regard to chip width. Afterwards the reshredded chips were conveyed to a flash drier and dried at approx. 120? C. The chips were then screened into two useful fractions (B: ?2.0 mm?2.0 mm and >0.32 mm?0.5 mm, C: ?4.0 mm?4.0 mm and >2.0 mm?2.0 mm), a coarse fraction (D: >4.0 mm?4.0 mm), which is reshreded, and a fine fraction (A: ?0.32 mm?0.5 mm).

(5) A mixture of 60 wt.-% of fraction B and 40 wt.-% of fraction C is used either as chips for single-layered chipboards.

(6) Spruce Wood Fibers

(7) The pulp was produced in a laboratory refining plant. An integrated steep conveyor transported the chips made from German spruce into the plant's preheater. Directly from the preheater, a continuously operating plug screw with integrated dewatering (MSD-Multi Screw Device) conveyed the material to be defibered into the pressure area of the plant. The material to be defibered was then plasticized in the digester at a digestion pressure of 9 bar under constant movement (3-4 min dwell time) and continuously conveyed to the refiner via a discharge screw and defibered. From the refiner, the fibers came via the tangential outlet and the blowline to the flash tube dryer and were dried.

(8) Methods:

(9) Measured Values and Measuring Methods

(10) Residual Particle Moisture Content:

(11) The moisture content of the particles (chips or fibers) before application of the binder (was measured according to EN 322:1993 by placing the particles in a drying oven at a temperature of (103?2) ? C. until constant mass has been reached.

(12) The water content of the particle/binder composition mixtures obtained in step a) is determined in an analogous manner. For this, a sample of the respective mixture (ca. 20 g) is weighed in moist condition (m.sub.1) and after drying (m.sub.0). The mass m.sub.0 is determined by drying at 103? C. to constant mass. Water content is calculated as follows: water content [in wt.-%]=[(m.sub.1?m.sub.0)/m.sub.0].Math.100.

(13) Press Time Factor:

(14) The press time factor is the press time, which is the time from closing to opening of the press, divided by the target thickness of the board. The target thickness refers to the board at the end of pressing step c) and is adjusted by the press conditions, i.e. by the distance between the top and bottom press plate, which is adjusted by inserting two steel spacing strips in the press.

(15) Press time factor [sec/mm]=time from closing to opening of the press [sec]: target thickness of the pressed board [mm]. For example, when a 10 mm chipboard is made with a press time of 120 sec, a press time factor of 12 sec/mm results.

(16) Density of the Boards:

(17) The density of the boards was measured according to EN 323:1993 and is reported as the arithmetic average of ten 50?50 mm samples of the same board.

(18) Transverse Tensile Strength of the Boards (Internal Bond):

(19) Transverse tensile strength of the boards (internal bond) was determined according to EN 319:1993 and is reported as the arithmetic average of ten 50?50 mm samples of the same board.

(20) Swelling in Thickness:

(21) Swelling in thickness after 24 h of the boards (24 h swelling) was determined according to EN 317:1993 and is reported as the arithmetic average of ten 50?50 mm samples of the same board

(22) Binder Amount:

(23) The binder amounts in the examples according to the present invention are reported as the total weight of the sum of the respective binder components polymer(s) A1 and component B1 in wt.-% based on the total dry weight of the wood particles (chips or fibers).

(24) The binder amounts in the comparative examples are reported as the total weight of the sum of all binder components in wt.-% (dry weight, which is the weight of the components without any water) based on the total dry weight of the wood particles (chips or fibers).

(25) Primary and secondary amine group amine group nitrogen content NC.sub.ps:

(26) The NC.sub.ps are measured by potentiometric titration according to EN ISO 9702:1998. The NC.sub.ps mean the weight of nitrogen of the primary and secondary amine groups per 100 g of polymer(s) A1 (given in wt.-%).

(27) Determination of the weight-average molecular weight M.sub.w:

(28) M.sub.w was determined by size exclusion chromatography under the following conditions: Solvent and eluent: 0.1% (w/w) trifluoroacetate, 0.1 M NaCl in distilled water Flow: 0.8 ml/min Injection volume: 100 ?l Samples are filtrated with a Sartorius Minisart RC 25 (0,2 ?m) filter Column material: hydroxylated polymethacrylate (TSKgel G3000PWXL) Column size: inside diameter 7.8 mm, length 30 cm Column temperature: 35? C. Detector: DRI Agilent 1100 UV GAT-LCD 503 [232 nm] Calibration with poly(2-vinylpyridine) standards in the molar mass range from 620 to 2890000 g/mole (from PSS, Mainz, Germany) and pyridine (79 g/mol) The upper integration limit was set to 29.01 mL The calculation of M.sub.w includes the lysine oligomers and polymers as well as the monomer lysine.

(29) The residual lysine monomer content of the polylysine solution was determined by HPLC/MS analysis under the following conditions: Injection volume: 10 ?l Eluent A: water+0.02% formic acid Eluent B: water Gradient

(30) TABLE-US-00001 time Eluent A Eluent B [min] [%] [%] 0 0 100 10 100 0 15 100 0 15.1 0 100 25 0 100 Switching from Eluent A to Eluent B after 15 min Flow: 0.8 ml/min Column HPLC: Primesep C, 250?3.2 mm, 5 ?m Column temperature: 30? C. Calibration with solution of L-lysine in water Mass spectrometer: Bruker Maxis (q-TOF) MS conditions: Ionization mode: ESI, negative Capillary: 3500 V Nebulizer: 1,4 bar Dry gas: 8 l/min Temperature: 200? C. analyzed ion: 145.0983 [M-H].sup.??0.005 amu.

(31) The residual lysine monomer content in Polymer A1 is given as wt.-% monomer based on the total weight of polylysine including the lysine monomer. For instance, the 50 wt.-% solution of Polylysine-5 with a lysine monomer content of 2.0 wt.-% contains 1 wt. % lysine monomer and 49% wt.-% lysine polymer comprising at least 2 condensed lysine units.

(32) Determination of ratio of ?-linkages to ?-linkages in polylysine (ratio ?/?):

(33) This ratio s/(can be determined by integration of the signals for CHNH.sub.2 and CHNH (?-linked) and CH.sub.2NH.sub.2 and CH.sub.2NH (?-linked) in the .sup.1H-NMR spectra of the polylysines. The NMR signals are as-signed by an .sup.1H, .sup.15N-HMBC experiment (Heteronuclear Multiple Bond Correlation).

(34) Abbreviations

(35) HA=Hydroxyaceton, PL=Polylysine, Glu=Glucose

EXAMPLES

Example 1

Synthesis of Polylysines 1-8

(36) 2200 g of L-lysine solution (50 wt.-% in water, ADM) was heated under stirring in an oil bath (external temperature 140? C.). Water was distilled off and the oil bath temperature was increased by 10? C. per hour until a temperature of 180? C. is reached. The reaction mixture was stirred for an additional hour at 180? C. (oil bath temperature) and then pressure was slowly reduced to 200 mbar. After reaching the target pressure, distillation was continued for another period of time t (as specified in the following Table 1). The product was hotly poured out of the reaction vessel, crushed after cooling and dissolved in water to give a 50 wt.-% solution.

(37) Residual lysine monomer content, NC.sub.ps and M.sub.w values were determined from this solution without any further purification. The residual lysine monomer is included in the calculation of M.sub.w.

(38) TABLE-US-00002 TABLE 1 synthesis and analytic data of the different Polylysine L-Lysine mono- NCps mer content ratio Polylysine t [min] Mw [g/mol] [wt. - %] [wt. - %]* ?/? Polylysine-1 120 1880 10.6 5.8 2.0 Polylysine-2 150 2600 10.0 2.6 2.2 Polylysine-3 180 3050 9.66 2.1 2.3 Polylysine-4 210 3590 9.26 1.3 2.3 Polylysine-5 255 5360 7.81 0.7 2.2 Polylysine-6 285 6690 6.76 0.4 2.3 Polylysine-7 300 9430 4.59 0.3 2.3 Polylysine-8 330 11080 3.27 0.3 2.3 *The residual lysine monomer content is given as wt. - % based on the total weight of polylysine including lysine monomer.

Example 2

(39) HDF boards (4 mm) with different polylysines (Polylysine-1 to Polylysine-8) and lysine

(40) Preparation of the resinated fibers (examples 2-1 to 2-8) In a mixer, 120 g of Polylysine-X solution (50 wt.-% in water) was sprayed onto 1.04 kg (1.0 kg dry weight) of spruce fibers (moisture content 4.1%) while mixing. After addition mixing was continued for 3 min.

(41) Preparation of the Resinated Fibers (Examples 2-0)

(42) In a mixer, 120 g of lysine solution (50 wt.-% in water) was sprayed onto 1.04 kg (1.0 kg dry weight) of spruce fibers (moisture content 4.1%) while mixing. After addition mixing was continued for 3 min.

(43) Pressing the Resinated Fibers to Fiberboards

(44) Immediately after resination 336 g of the resinated fibers were scattered into a 30?30 cm mold and pre-pressed under ambient conditions (0.4 N/mm2). Subsequently, the pre-pressed fiber mat thus obtained was removed from the mold, transferred into a hot press and pressed to a thickness of 4 mm to give a HDF (temperature of the press plates 210? C., max pressure 4 N/mm.sup.2). The pressing time was 40 s.

(45) TABLE-US-00003 TABLE 2 HDF boards, 4 mm, binder amount 6 wt. - % (solid/dry wood), press time factor = 10 sec/mm. polymer(s) Mw internal bond swelling 24 h density Example A1 [g/mol] [N/mm.sup.2] [%] [kg/m.sup.3] 2-0 Lysine* 146 no boards 2-1 PL-1 1880 0.77 0.38 801 2-2 PL-2 2600 0.86 0.33 786 2-3 PL-3 3050 0.93 0.34 800 2-4 PL-4 3590 1.21 0.32 806 2-5 PL-5 5360 1.20 0.32 801 2-6 PL-6 6690 1.15 0.31 799 2-7 PL-7 9430 0.94 0.34 803 2-8 PL-8 11080 no boards *Lysine was used instead of polymer(s) A1, PL = Polylysine

Example 3

(46) HDF boards (2 mm) with Polylysine-4

(47) Preparation of the Resinated Fibers

(48) In a mixer, 120 g of Polylysine-4 solution (50 wt.-% in water) was sprayed onto 1.04 kg (1.0 kg dry weight) of spruce fibers (moisture content 4.1%) while mixing. After addition mixing was continued for 3 min.

(49) Pressing the Resinated Fibers to Fiberbaords:

(50) Immediately after resination 168 g of the resinated fibers were scattered into a 30?30 cm mold and pre-pressed under ambient conditions (0.4 N/mm2). Subsequently, the pre-pressed fiber mat thus obtained was removed from the mold, transferred into a hot press and pressed to a thickness of 2 mm to give a HDF (temperature of the press plates 210? C., max pressure 4 N/mm.sup.2). The pressing time was 20 s.

(51) TABLE-US-00004 TABLE 3 HDF board, 2 mm binder amount 6 wt. - % (solid/dry wood), press time factor = 10 sec/mm. Polymer(s) Mw internal bond swelling 24 h density Example A1 [g/mol] [N/mm.sup.2] [%] [kg/m.sup.3] 3-1 Polylysine- 3590 1.28 0.40 809 4

Example 4

(52) HDF boards (4 mm) with different ratios of Polylysin-4 and glucose/hydroxyacetone

(53) Preparation of the Resinated Fibers

(54) In a mixer, Y g of Polylysine-4 (PL-4) solution (50-wt.-% in water) was sprayed onto 1.04 kg (1.00 kg dry weight) of spruce fibers (moisture content 4.1%) while mixing. Subsequently, Z g of a glucose solution (50 wt.-% in water) or X g of a hydroxyaceton solution (50 wt.-% in water) was sprayed onto the mixture while mixing (Y, Z and X are given in table 4). After addition, mixing was continued for 3 min.

(55) TABLE-US-00005 TABLE 4 Amounts of binder for Example 4-1 to Example 4-8 Polymer A1 Component B1 amount PL-4 ratio of PL in amount Glu amount HA solution (Y) binder** solution (Z) solution (X) Example [g] [%] [g] [g] 4-1 120 100 0 0 4-2 110 91.6 10 0 4-3 100 83.3 20 0 4-4 80 66.7 40 0 4-5 60 50.0 60 0 4-6 40 33.0 80 0 4-7 20 16.7 100 0 4-8 0 0 120 0 4-9 92 76.6 0 28 4-10 92 100 0 0 **weight ratio of A1 to (A1 + B1) based on solids

(56) Pressing the Resinated Fibers:

(57) Immediately after resination 336 g of the resinated fibers were scattered into a 30?30 cm mold and pre-pressed under ambient conditions (0.4 N/mm2). Subsequently, the pre-pressed fiber mat thus obtained was removed from the mold, transferred into a hot press and pressed to a thickness of 4 mm to give a HDF (calculated density of 800 kg/m.sub.3) (temperature of the press plates 210? C., max pressure 4 N/mm.sup.2).

(58) The pressing time was 40 s.

(59) TABLE-US-00006 TABLE 5 HDF boards, 4 mm binder amount mainly 6 wt.-% (solid/dry wood), press time factor = 10 sec/mm ratio of Poly- amount amount amount PL in internal swelling Ex- mer(s) PL-4 Glu HA binder*** bond 24 h density ample A1 [wt.-%]** [wt.-%]** [wt.-%] ** [%] [N/mm.sup.2] [%] [kg/m] 4-1 PL-4 6.0 0.0 100 1.21 0.32 806 4-2 PL-4 5.5 0.5 91.7 1.20 0.32 796 4-3 PL-4 5.0 1.0 83.3 1.18 0.34 800 4-4 PL-4 4.0 2.0 66.7 1.05 0.34 808 4-5 PL-4 3.0 3.0 50.0 0.71 0.37 778 4-6 PL-4 2.0 4.0 33.3 0.68 0.48 820 4-7 PL-4 1.0 5.0 16.7 no boards 4-8 PL-4 0.0 6.0 0 no boards 4-9 PL-4 4.6 1.4 76.7 1.07 0.33 799 4-10 PL-4 4.6 100 1.09 0.34 809 ** based on solid per dry wood ***weight ratio of A1 to (A1 + B1) based on solids

Example 5

(60) HDF boards (4 mm) with different amounts of Polylysine-6 and glucose as comparative example (EP 3611225A2, Example 9 and 11, table 4)

(61) Preparation of the Resinated Fibers

Example 5-0

(62) In a mixer, 100 g of Polylysine-6 solution (50 wt.-% in water) was sprayed onto 1.04 kg (1.0 kg dry weight) of spruce fibers (moisture content 4.1%) while mixing. Subsequently, 20 g of a glucose solution (50 wt.-% in water) was sprayed onto the mixture while mixing. After addition mixing was continued for 3 min.

Comparative Example 5-1

(63) In a mixer, 60 g of Polylysine-6 solution (50 wt.-% in water) was sprayed onto 1.04 kg (1.0 kg dry weight) of spruce fibers (moisture content 4.1%) while mixing. Subsequently, 60 g of a glucose solution (50 wt.-% in water) was sprayed onto the mixture while mixing. After addition mixing was continued for 3 min.

Comparative Example 5-2

(64) In a mixer, 20 g of Polylysine-6 (PL-6) solution (50 wt.-% in water) was sprayed onto 1.04 kg (1.0 kg dry weight) of spruce fibers (moisture content 4.1%) while mixing. Subsequently, 100 g of a glucose solution (50 wt.-% in water) was sprayed onto the mixture while mixing. After addition mixing was continued for 3 min.

(65) Pressing the Resinated Fibers:

(66) Immediately after resination 336 g of the resinated fibers were scattered into a 30?30 cm mold and pre-pressed under ambient conditions (0.4 N/mm2). Subsequently, the pre-pressed fiber mat thus obtained was removed from the mold, transferred into a hot press and pressed to a thickness of 4 mm to give a HDF (temperature of the press plates 210? C., max pressure 4 N/mm.sup.2). The pressing time was 40 s.

(67) TABLE-US-00007 TABLE 6 HDF boards, 4 mm, binder amount 6 wt.-% (solid/dry wood), press time factor = 10 sec/mm. ratio of Poly- amount amount PL in internal swelling Ex- mer(s) PL-6 Glucose binder*** bond 24 h density ample A1 [wt.-%]** [wt.-%]** [%] [N/mm2] [%] [kg/m] 5-0 PL-6 5.0 1.0 83.3 1.07 0.35 804 5-1 PL-6 3.0 3.0 50.0 0.64 0.41 781 5-2 PL-6 1.0 5.0 16.7 no boards **based on solid per dry wood ***weight ratio of A1 to (A1 + B1) based on solids

Example 6

(68) Single-layered chipboards with different polymer(s) A1

(69) Preparation of the Resinated Chips

(70) In a mixer 648 g of Polylysine-X solution (50 wt.-% in water) was sprayed onto 5.56 kg (5.40 kg dry weight) of spruce wood chips (moisture content 3.0%) while mixing. Subsequently, 48.6 g of water was sprayed onto the mixture while mixing to adjust the final moisture of the resinated chips. After addition of the water mixing was continued for 3 min.

(71) Pressing the Resinated Chips to Chipboards

(72) Immediately after resination, 1.10 kg of the chips/binder mixture were scattered into a 30?30 cm mold and pre-pressed under ambient conditions (0.4 N/mm.sup.2). Subsequently, the pre-pressed chip mat thus obtained was removed from the mold, transferred into a hot press and pressed to a thickness of 16 mm to give a chipboard (temperature of the press plates 210? C., max pressure 4 N/mm.sup.2). The pressing time was 160 sec.

(73) TABLE-US-00008 TABLE 7 chipboards 16 mm binder amount 6 wt. - % (solid/ dry wood), press time factor = 10 sec/mm pressed with different Polylysine polymer(s) Mw internal bond swelling density Example A1 [g/mol] [N/mm{circumflex over ()}2] 24 h [%] [kg/m{circumflex over ()}3] 6-1 Polylysine-1 1880 no boards** 6-2 Polylysine-2 2600 no boards** 6-3 Polylysine-3 3050 no boards** 6-4 Polylysine-4 3590 no boards** 6-5 Polylysine-5 5360 no boards** 6-6 Polylysine-6 6690 no boards** 6-7 Polylysine-7 9430 no boards** 6-8 Polylysine-8 11080 no boards** **no board means that the resulting material after pressing was not a sound chipboard andshowed fractures, blows and/or bursts

(74) Even the prolongation of the pressing time to 240 s did not lead to sound chipboards.

(75) Surprisingly, it was found that fiber boards with good mechanical properties can be formed with polylysine, whereas chipboards cannot be formed with the same type and amount of polylysine binder.