BINDER FOR WOOD-BASED PANELS COMPRISING AMINO ACID POLYMER AND POLYALDEHYDE COMPOUND

Abstract

The invention relates to a process for producing a lignocellulosic composite comprising one or more lignocellulosic composite layers. The process comprises S1) providing or preparing a mixture, at least comprising: lignocellulosic particles and a binder composition, the binder composition comprising as components at least: c1) one or more amino acid polymers having two or more primary amino groups and c2) one or more polyaldehyde compounds. The process further comprises S2) compacting the mixture from step S1) to receive a compacted mixture, and S3) applying heat and optionally pressure to the compacted mixture from step S2), so that the binder of the binder composition hardens and a lignocellulosic composite results. The invention further relates to the use of the lignocellulosic composite. Moreover, the invention relates to a kit for producing a binder composition, for use in the production of a lignocellulosic composite, and to the use of such binder composition.

Claims

1.-17. (canceled)

18. A process for producing a lignocellulosic composite comprising one or more lignocellulosic composite layers, comprising at least the following steps: S1) providing or preparing a mixture, at least comprising: lignocellulosic particles and a binder composition, comprising as components at least: c1) one or more amino acid polymers having two or more primary amino groups, comprising one or more polylysines and c2) one or more polyaldehyde compounds, selected from the group consisting of compounds having two or more aldehyde groups and compounds having tautomers having two or more aldehyde groups; S2) compacting the mixture from step S1) to receive a compacted mixture, and S3) applying heat and optionally pressure to the compacted mixture from step S2), so that the binder of the binder composition hardens and a lignocellulosic composite results.

19. The process according to claim 18, wherein the one or more amino acid polymers of component c1) of the binder composition comprise one or more polylysines, wherein the one or more polylysines have a weight-average molecular weight M.sub.w of 800 g/mol; and/or have a weight-average molecular weight M.sub.w of 10000 g/mol; and/or have a weight-average molecular weight M.sub.w in the range of 800 g/molM.sub.w10000 g/mol; and/or comprise as monomers integrated in their polymer structure at least 85 wt.-% of lysine monomers.

20. The process according to claim 18, wherein the one or one of the more or all of the more polyaldehyde compounds of component c2) of the binder composition are selected from the group consisting of oxidized starch, glyoxal, dialdehyde cellulose, propanedial, butanedial, pentanedial, hexanedial, furan-2,5-dicarbaldehyde, 5-(hydroxymethyl) furan-2-carbaldehyde (HMF), 3-hydroxy-2-oxo-propanal, and mixtures thereof.

21. The process according to claim 18, wherein the mixture further comprises one or more alpha-hydroxy carbonyl compounds.

22. The process according to claim 21, wherein the one or more alpha-hydroxy carbonyl compounds are selected from the group consisting of glycolaldehyde, glyceraldehyde, 1,3-dihydroxyacetone, hydroxyacetone, arabinose, xylose, glucose, mannose, fructose, saccharose, and mixtures thereof.

23. The process according to claim 18, wherein the ratio of (i) the total weight of the one or more amino acid polymers of component c1) of the binder composition: (ii) the total weight of the one or more polyaldehyde compounds of component c2) of the binder composition is in the range of 60:40 to 95:5, and/or the molar ratio of (i) the primary amino groups provided by the one or more amino acid polymers of component c1) of the binder composition to (ii) the aldehyde groups provided by the one or more polyaldehyde compounds of component c2) of the binder composition is in the range of 0.1 to 1.2.

24. The process according to claim 18, wherein the binder composition provided or prepared in step S1) further comprises a carrier liquid.

25. The process according to claim 24, wherein component c1), the one or more amino acid polymers, is present in the binder composition in a total amount in the range of from 20 to 50 wt.-%, relative to the totalized weight of components c1) to c2) and carrier liquid; and/or component c2), the one or more polyaldehyde compounds, is present in the binder composition in a total amount in the range of from 3 to 20 wt.-%, relative to the total weight of components c1) to c2) and carrier liquid; and/or the pH-value of the binder composition is in the range of from 10 to 14.

26. The process according to claim 18, wherein in the mixture provided or prepared in step S1) of the process, the total amount of component c1), the one or more amino acid polymers of the binder composition, and of component c2), the one or more polyaldehyde compounds of the binder composition, is in the range of from 3 to 8 wt.-%, relative to the total amount of the lignocellulosic particles in an oven-dry state of the mixture.

27. The process according to claim 18, wherein the mixture in step S1) is prepared by providing or preparing in a first step S1-1) the binder composition comprising at least components c1) and c2) and in a second step S1-2), contacting, the binder composition provided or prepared in step S1-1) with the lignocellulosic particles.

28. The process according to claim 18, wherein the lignocellulosic composite is a lignocellulosic board selected from the group consisting of: high-density fiberboard (HDF); medium-density fiberboard (MDF); low-density fiberboard (LDF); wood fiber insulation board; oriented strand board (OSB); chipboard; and natural fiber board, wherein the lignocellulosic board is a single-layer lignocellulosic board or multilayer lignocellulosic board.

29. The process according to claim 18, wherein the process of producing a lignocellulosic composite comprises one, two, three, more than three, or all of the following steps: preparing a layer of the mixture provided or prepared in step S1), and in step S2) compacting this layer, preparing a multilayer lignocellulosic composite comprising one or more lignocellulosic composite layers, providing or preparing at least a first and a second individual mixture, and using said first and second individual mixtures for making a first and a second layer of the multilayer lignocellulosic composite, preparing a multilayer lignocellulosic composite, preparing two or more layers, each layer comprising lignocellulosic particles and a binder, wherein in the two or more layers the lignocellulosic particles and/or the binders are the same or different, compacting, in step 2), the mixture in one or more two stages, during or after compacting in step S2), pre-heating the mixture, heating in step S3) in such way, that during step 3) or at the end of step S3) the temperature in the center of formed lignocellulosic composite may be at least 80 C., and applying a pressure in the range of from of 0.1 to 10 MPa in step S3) to the compacted mixture from step S2).

30. The process according to claim 29, wherein the heating in step S3) comprises applying a high-frequency electrical field.

31. A binder composition or mixture for producing a lignocellulosic composite, comprising as components at least: c1) one or more amino acid polymers having two or more primary amino groups and c2) one or more polyaldehyde compounds wherein the binder composition is as defined in claim 18.

32. A lignocellulosic composite, obtainable or obtained according to a process according to claim 18, or construction product comprising such lignocellulosic composite.

33. The lignocellulosic composite according to claim 32, wherein the lignocellulosic composite is a lignocellulosic board selected from the group consisting of high-density fiberboard (HDF) medium-density fiberboard (MDF) low-density fiberboard (LDF) wood fiber insulation board oriented strand board (OSB) chipboard, and natural fiber board.

34. (canceled)

35. (canceled)

36. (canceled)

37. (canceled)

Description

EXAMPLES

[0183] The following examples are meant to further explain and illustrate the present invention without limiting its scope.

A. Materials Used

[0184] Glucose monohydrate (>99%), Sigma Aldrich, Spain [0185] Fructose (>99%), Sigma Aldrich, US [0186] Hexamethylene diamine (HMDA, >99%), Acros Organic [0187] L-Lysine (98%), Sigma Aldrich, Switzerland [0188] L-Lysine solution (50% in water), ADM animal nutrition, US [0189] Carboxymethylcellulose sodium salt (M.sub.w ca 250.000), Sigma-Aldrich, US [0190] 5-Hydroxymethyl furfural (HMF), aber GmbH, US [0191] Spruce wood chips (from Germany, Institut fr Holztechnologie Dresden, Germany):

[0192] The spruce wood chips (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 mm2.0 mm and >0.32 mm0.5 mm; C: 4.0 mm4.0 mm and >2.0 mm2.0 mm), a coarse fraction (D: >4.0 mm4.0 mm), which is re-shreded, and a fine fraction (A: 0.32 mm0.5 mm). A mixture of 60 wt.-% of fraction B and 40 wt.-% of fraction C is used as chips for single-layered chipboards (core layer chips)

B. Measured Values and Measuring Methods

1. Press Time Factor:

[0193] 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 (process step S3) 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 (if the hot press was used), or by the automatic distance control (if the HF press was used). 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 140 sec, a press time factor of 14 sec/mm results.

2. Density of the Boards:

[0194] The density of the boards was measured according to EN 323:1993 and is reported as the arithmetic average of ten 5050 mm samples of the same board.

3. Transverse Tensile Strength of the Boards (Internal Bond)

[0195] Transverse tensile strength of the boards (internal bond) was determined according to EN 319:1993 and is reported as the arithmetic average of ten 5050 mm samples of the same board.

4. Swelling in Thickness:

[0196] 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 5050 mm samples of the same board.

5. Binder Amount:

[0197] 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 amino acid polymer and polyaldehyde in wt.-%, based on the total dry weight of the wood particles (chips).

[0198] 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).

6. Primary and Secondary Amino Group Nitrogen Content NC.SUB.ps.:

[0199] The primary and secondary amino group nitrogen contents are measured by potentiometric titration according to EN ISO 9702:1998. The NC.sub.ps means the weight of nitrogen of the primary and secondary amino groups per 100 g of amino acid polymer (given in wt.-%).

7. Determination of the Weight-Average Molecular Weight M.SUB.w

[0200] M.sub.w was determined by size exclusion chromatography under the following conditions: [0201] Solvent and eluent: 0.1% (w/w) trifluoroacetate, 0.1 M NaCl in distilled water [0202] Flow: 0.8 ml/min [0203] Injection volume: 100 l [0204] Samples were filtrated with a Sartorius Minisart RC 25 (0.2 m) filter [0205] Column material: hydroxylated polymethacrylate (TSKgel G3000PWXL) [0206] Column size: inside diameter 7.8 mm, length 30 cm [0207] Column temperature: 35 C. [0208] Detector: DRI Agilent 1100 UV GAT-LCD 503 [232 nm] [0209] Calibration with poly(2-vinylpyridine) standards in the molar mass range from 620 to 2890000 g/mole (from Polymer Standard Service GmbH, Mainz, Germany) and pyridine (79 g/mol). [0210] The upper integration limit was set to 29.01 mL. [0211] The calculation of M.sub.w includes the lysine oligomers and polymers as well as the monomer lysine.

[0212] The residual lysine monomer content of the polylysine solution was determined by HPLC/MS analysis, under the following conditions: [0213] Injection volume: 10 l [0214] Eluent A: water+0.02% formic acid [0215] Eluent B: water [0216] Gradient

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 [0217] Switching from Eluent A to Eluent B after 15 min [0218] Flow: 0.8 ml/min [0219] Column HPLC: Primesep C, 2503.2 mm, 5 m [0220] Column temperature: 30 C. [0221] Calibration with solution of L-lysine in water [0222] Mass spectrometer: Bruker Maxis (q-TOF) [0223] MS conditions: [0224] Ionization mode: ESI, negative [0225] Capillary: 3500 V [0226] Nebulizer: 1.4 bar [0227] Dry gas: 8 l/min [0228] Temperature: 200 C. [0229] analyzed ion: 145.0983 [M-H].sup.0.005 amu.

[0230] The residual lysine monomer content in polylysine 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 (see table 1 below) 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.

8. Determination of Ratio of -Linkages to -Linkages in Polylysine (Ratio /);

[0231] This ratio / is 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 1H-NMR spectra of the respective polylysines. The NMR signals are assigned by an 1H, 15N-HMBC (Heteronuclear Multiple Bond Correlation) experiment.

C. Preparation Examples

Preparation of Samples of Different Polylysines:

[0232] 2200 g of L-lysine solution (50% 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. had been reached. The reaction mixture was stirred for an additional hour at 180 C. (oil bath temperature) and the pressure was then slowly reduced to 200 mbar. After reaching the target pressure, distillation was continued for another period of time t (as specified in Table 1 below). The hot product was poured out of the reaction vessel, crushed after cooling, and dissolved in water, to give a 50 wt.-% solution. Polylysine samples Polylysine 1 to Polylysine 6 were produced according to this procedure. The reaction conditions applied in each case and certain parameters measured of said different polylysines are shown in Table 1 below.

[0233] In these examples, the lysine monomer contributed a certain amount of amino groups to the binder.

[0234] Residual lysine monomer content, NC.sub.ps and M.sub.w were each determined from this solution without any further purification. The residual lysine monomer is included in the calculation of M.sub.w.

TABLE-US-00002 TABLE 1 Reaction conditions in the synthesis and properties of different samples of polylysines L-Lysine monomer Polylysine t M.sub.w NC.sub.ps content ratio type [min] [g/mol] [wt.-%] [wt.-%]* / Polylysine- 90 1510 11.0 10.3 1.9 1 Polylysine- 120 2010 10.5 5.9 2.1 2 Polylysine- 150 2240 10.2 4.2 2.2 3 Polylysine- 180 2740 9.80 2.5 2.3 4 Polylysine- 210 3360 9.50 2.0 2.3 5 Polylysine- 240 3690 9.15 1.3 2.2 6 *The residual lysine monomer content is given as wt.-% based on the total weight of polylysine including lysine monomer.

Comparative Binder Composition-1

[0235] 161 g of glucose monohydrate, 146 g of fructose and 161 g of L-lysine were mixed with 35 g of water and slowly heated (110 C. oil bath temperature). At 94 C. the mixture foamed and turned black. The reaction was stopped. The resulting reaction mixture contained a solid and was not completely soluble in water.

Comparative Binder Composition-2

[0236] 286 g of glucose monohydrate, 260 g of fructose and 286 g of L-lysine were mixed with 174 g of water and slowly heated (100 C. oil bath temperature). At 90 C. the mixture foamed and turned dark brown. The oil bath was removed for 10 minutes. The reaction was heated up again for 10 min to 100 C. until gas formation stopped. After cooling down to RT, the mixture was filled in bottles and stored at 60 C. for 48 h.

Comparative Binder Composition-3

[0237] 235 g of hexamethylene diamine was dissolved in 730 g of water. 791 g of fructose and 853 g of glucose monohydrate were slowly added and stirred at room temperature for one hour.

Comparative Binder Composition-4

[0238] 22.5 g of carboxymethylcellulose sodium salt (NaCMC, M.sub.w ca. 250,000) was dissolved in 600 g of water. 67.5 g of hexamethylene diamine and 360 g of glucose monohydrate were slowly added and stirred at room temperature for 24 h.

Example 1 (According to the Invention)

[0239] Note: The term resinated chips is generally used herein for the mixture of the chips with the binder composition and additionally added water.

[0240] In a mixer, a mixture of 499 g of Polylysine-2 solution (50 wt.-% in water), 149 g of a HMF solution (50 wt.-% HMF in water) and 100 g of water was sprayed onto 5.55 kg (5.40 kg dry weight plus 150 g water (from residual particle moisture content) of spruce core layer chips (moisture content 2.8%) while mixing. After addition of the mixture mixing was continued for 3 min. Certain information on the components used for preparing the binder composition of this example and on certain parameters measured of resulting single-layer chipboards are shown in Table 2 below.

Comparative Example 2*

[0241] Comparative Binder composition-1 was inhomogeneous. Spraying of Comparative Binder composition-1 onto the chips was not possible. Attempts to mix Comparative Binder composition-1 with the chips by pouring the binder composition onto the chips and stirring also failed to give an even mixture. Nevertheless, the inhomogeneous mixture was used for pressing. Certain information on the components used for preparing the binder composition of this example and on certain parameters measured of resulting single-layer chipboards are shown in Table 2 below.

Comparative Example 3*

[0242] In a mixer, a mixture of 404 g of Comparative Binder composition-2 and 244 g of water was sprayed onto 5.55 kg (5.40 kg dry weight plus 150 g water from residual particle moisture content) of spruce core layer chips (moisture content 2.8%) while mixing. 100 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. Certain information on the components used for preparing the binder composition of this example and on certain parameters measured of resulting single-layer chipboards are shown in Table 2 below.

Comparative Example 4*

[0243] In a mixer, a mixture of 469 g of Comparative Binder composition-3 and 179 g of water was sprayed onto 5.55 kg (5.40 kg dry weight plus 150 g water from residual particle moisture content) of spruce core layer chips (moisture content 2.8%) while mixing. 100 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. Certain information on the components used for preparing the binder composition of this example and on certain parameters measured of resulting single-layer chipboards are shown in Table 2 below.

Comparative Example 5*

[0244] In a mixer, 816 g of Comparative Binder composition-4 was sprayed onto 5.51 kg (5.40 kg dry weight plus 105 g water from residual particle moisture content) of spruce core layer chips (moisture content 1.9%) while mixing. Thereafter, mixing was continued for 3 min. Certain information on the components used for preparing the binder composition of this example and on certain parameters measured of resulting single-layer chipboards are shown in Table 2 below.

Comparative Example 6*

[0245] In a mixer, a mixture of 499 g of Polylysine-2 solution (50 wt.-% in water), 164 g of glucose monohydrate (corresponding to 149 g of glucose) and 285 g of water was sprayed onto 5.51 kg (5.40 kg dry weight plus 105 g water from residual particle moisture content) of spruce core layer chips (moisture content 1.9%) while mixing. After addition of the mixture, mixing was continued for 3 min. Certain information on the components used for preparing the binder composition of this example and on certain parameters measured of resulting single-layer chipboards are shown in Table 2 below.

Pressing the Resinated Chips to Chipboards (Example 1 According to the Invention and Comparative Examples 2* to 6*)

[0246] Immediately after resination, 600 g of the chips/binder mixture were scattered into a 3030 cm mold and pre-compacted under ambient conditions (0.4 N/mm.sup.2). Subsequently, the pre-compacted chip mat thus obtained was removed from the mold, transferred into a hot press and pressed to a thickness of 10 mm to give a chipboard (temperature of the press plates 210 C., max. pressure 4 N/mm.sup.2, pressing time 140 sec). Certain information on the components used for preparing the binder composition of this example and on certain parameters measured of resulting single-layer chipboards are shown in Table 2 below.

TABLE-US-00003 TABLE 2 Single-layered chipboards, 10 mm, with different binder compositions according to the invention and comparative examples, binder amount 6 wt.-% (solids/dry wood), press time factor 14 sec/mm B A HMF or com- Internal Amino acid polymer parative binder bond 24 h or Comparative component Ratio.sup.1) Density, strength, swelling, Ex. binder component glucose A:B [kg/m.sup.3] [N/mm.sup.2] [%] 1 Polylysine-2 HMF 77:23 623 0.47 62 2* Comparative no board Binder-1 (Glucose/ fructose/lysine) 3* Comparative 611 0.11 n.q. Binder-2 (Glucose/ fructose/lysine) 4* Comparative 609 0.06 n.q. Binder-3 (Glucose/ fructose/HMDA) 5* Comparative 620 0.20 n.q. Binder-4 (Glucose/ HMDA/NaCMC) 6* Polylysine-2 Glucose 77:23 619 0.31 80 *Comparative Example .sup.1)ratio by weight n.p. = production of a chip board was not possible, since Comparative Binder-1 was inhomogeneous and could not be evenly distributed on the chips; n.q. = not quantifiable since test sample fell to pieces within 24 h; no board means that the resulting material after pressing was not a sound chipboard and showed fractures, blows and/or bursts.

[0247] The above results show that a binder according to the invention based on polylysine and polyaldehyde compound gives boards having improved properties, as compared to boards prepared by processes not according to the present invention, e.g. prepared with a comparative binder based on amine and sugar compound. A board prepared by a process 15 not according to the present invention but prepared with a binder comprising polylysine and a reducing sugar (here: glucose, cf. Ex. 6 in table 2 above) showed a lower internal bond strength and a higher 24 h swelling value than a board prepared by a process according to the present invention (cf. Ex. 1 in table 2 above).

[0248] The following examples 7 to 11 (all according to the invention) pertain to the manufacture of single-layered chipboards with Polylysine-2 and HMF and to different ways of application. Certain information on the components used for preparing the binder compositions of examples 7 to 11 and on certain parameters measured of resulting single-layer chipboards are shown in Table 3 below.

Example 7: Separate Application of the Binder Composition to the Wood Chips

[0249] In a mixer, 454 g of Polylysine-2 solution (50 wt.-% in water) was sprayed onto 5.55 kg (5.40 kg dry weight) of spruce core layer chips (moisture content 2.8%) while mixing. Subsequently, 194 g of a HMF solution (50 wt.-% HMF in water) was sprayed onto the mixture while mixing. Finally, 100 g of water was sprayed onto the mixture while mixing, to adjust the final moisture of the resinated chips.

Example 8: Separate Application of the Binder System to the Wood Chips

[0250] In a mixer, 194 g of a HMF solution (50 wt.-% HMF in water) was sprayed onto 5.55 kg (5.40 kg dry weight) of spruce core layer chips (moisture content 2.8%) while mixing. Subsequently, 454 g of Polylysine-2 solution (50 wt.-% in water) was sprayed onto the mixture. Finally, 100 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.

Examples 9 to 11: Mixed Application of the Binder Composition to the Wood Chips

[0251] 2.00 kg of Polylysine-2 solution (50 wt.-% in water) and 857 g of a HMF solution (50 wt.-% HMF in water) were mixed by stirring for 1 min at 22 C. In a mixer 648 g of this mixture was sprayed either immediately after mixing or after a waiting time (stored in a closed box at 22 C.) as given in the Table 3, to 5.55 kg (5.40 kg dry weight) of spruce core layer chips (moisture content 2.8%) while mixing. Subsequently, 100 g of water was sprayed onto the mix while mixing to adjust the final moisture of the resinated chips. After addition of the water, mixing was continued for 3 min.

Examples 7 to 11: Pressing the Resinated Chips to Chipboards

[0252] Immediately after resination, 600 g of the chips/binder mixture were scattered into a 3030 cm mold and pre-compacted under ambient conditions (0.4 N/mm.sup.2). Subsequently, the pre-compacted chip mat thus obtained was removed from the mold, transferred into a hot press and pressed to a thickness of 10 mm to give a chipboard (temperature of the press plates 210 C., max pressure 4 N/mm.sup.2, pressing time 140 sec).

TABLE-US-00004 TABLE 3 Single-layered chipboards, 10 mm, binder amount (components A + B): 6 wt.-% (solids/dry wood), press time factor = 14 sec/mm Weight Waiting Internal 24 h ratio time, Density, bond, swelling, Example A B A:B Application [h] [kg/m.sup.3] [N/mm.sup.2] [%] 7 PL-2 HMF 70:30 sep. 622 0.34 78 8 PL-2 HMF 70:30 sep.* 621 0.35 80 9 PL-2 HMF 70:30 mix 0.25 628 0.48 61 10 PL-2 HMF 70:30 mix 1 625 0.47 61 11 PL-2 HMF 70:30 mix 4 619 0.45 63 Waiting time = time between end of mixing of Polylysine-2 and HMF and start of spraying the binder composition mixture onto the chips, PL-2 = Polylysine-2 solution (50 wt.-% in water), for preparation see above; n.d. = not determined sep. = separate application (first Polylysine-2, second HMF) sep.* = separate application (first HMF, second Polylysine-2) mix = application of a mixture of Polylysine-2 and HMF

[0253] The results in Table 3 above show that one can work with a mixture of amino acid polymer (e.g. polylysine) and polyaldehyde (e.g. HMF), or with a separate application of the two components onto the chips, while use of the mixture is preferred. The system furthermore tolerates a long waiting time between preparation of the mixture and application onto the chips.

Examples 12* to 18: Preparation of the Resinated Chips

[0254] In a mixer, a mixture of 499 g of L-lysine solution (50 wt.-% in water, Comparative Example 12*) or Polylysine solution (50 wt.-% in water, Polylysine-1 to Polylysine-6, Examples 13 to 18), 149 g of a HMF solution (50 wt.-% HMF in water) and 100 g of water was sprayed onto 5.54 kg (5.40 kg dry weight) of spruce core layer chips (moisture content 2.8%) while mixing. After addition of the mixture, mixing was continued for 3 min.

Examples 12* to 18: Pressing the Resinated Chips to Chipboards

[0255] Immediately after resination, 600 g of the chips/binder mixture were scattered into a 3030 cm mold and pre-compacted under ambient conditions (0.4 N/mm.sup.2). Subsequently, the pre-compacted chip mat thus obtained was removed from the mold, transferred into a hot press and pressed to a thickness of 10 mm to give a chipboard (temperature of the press plates 210 C., max. pressure 4 N/mm.sup.2, pressing time 140 sec).

[0256] Certain information on the components used for preparing the binder compositions of example 12 (for comparison) and examples 13 to 18 (all according to the invention) and on certain parameters measured of resulting single-layer chipboards are shown in Table 4 below.

TABLE-US-00005 TABLE 4 Single-layered chipboards, 10 mm, binder amount (A + B): 6 wt.-% (solids/dry wood), mixed application, press time factor 14 sec/mm Internal M.sub.w of A .sup.2), Weight Density, bond, Example A.sup.1) [g/mol] B ratio A:B [kg/m.sup.3] [N/mm.sup.2] 12* L-Lysine 146 HMF 77:23 No board 13 PL-1 1510 HMF 77:23 615 0.30 14 PL-2 2010 HMF 77:23 626 0.47 15 PL-3 2240 HMF 77:23 629 0.48 16 PL-4 2740 HMF 77:23 625 0.53 17 PL-5 3360 HMF 77:23 620 0.52 18 PL-6 3690 HMF 77:23 626 0.50 *Comparative Example, .sup.1)Amino acid polymer or comparative component .sup.2) M.sub.w of the amino acid polymers are measured by size exclusion chromatography. PL-1 to PL-6: solutions (50 wt.-% in water) of polylysine-1 to polylysine 6 (for preparation and properties see description and Table 1 above).

[0257] The above results in Table 4 show that different weight average molecular weights of the amino acid polymer (polylysines) work well, whereas amino acid (lysine) monomer does not work. There is an optimal range for the weight average molecular weight of the amino acid polymer (polylysine), at around 3000 g/mol.

[0258] The following examples 19 to 21 (all according to the invention) pertain to the manufacture of single-layered chipboards with Polylysine-2 and different weights of HMF. Certain information on the components used for preparing the binder compositions of examples 19 to 21 and on certain parameters measured of resulting single-layer chipboards are shown in Tables 5 and 6 below.

[0259] In a mixer, a mixture of an amount x1 of Polylysine-2 solution (50 wt.-% in water), an amount y1 of HMF solution (50 wt.-% HMF in water) and 100 g of water, was sprayed onto 5.55 kg (5.40 kg dry weight) of spruce core layer chips (moisture content 2.8%) while mixing. After addition of the mixture mixing was continued for 3 min.

TABLE-US-00006 TABLE 5 Amount x1 of Polylysine-2 solution and amount y1 of HMF solution Amount of Polylysine- 2 solution Amount of HMF solution (50 wt.-% in water) (50 wt.-% in water) Example x1 [g] y1 [g] 19 583 64.5 20 518 130 21 454 194

Examples 19 to 21: Pressing the Resinated Chips to Chipboards

[0260] Immediately after resination, 600 g of the chips/binder mixture were scattered into a 3030 cm mold and pre-compacted under ambient conditions (0.4 N/mm.sup.2). Subsequently, the pre-compacted chip mat thus obtained was removed from the mold, transferred into a hot press and pressed to a thickness of 10 mm to give a chipboard (temperature of the press plates 210 C., max pressure 4 N/mm.sup.2, pressing time 140 sec).

TABLE-US-00007 TABLE 6 Single-layered chipboards, 10 mm, binder amount (components A + B): 6 wt.-% (solids/dry wood), mixed application, press time factor 14 sec/mm Component Weight ratio Density, Internal bond, Example A.sup.1) B A:B [kg/m.sup.3] [N/mm.sup.2] 19 Polylysine-2 HMF 90:10 601 0.31 20 Polylysine-2 HMF 80:20 614 0.41 21 Polylysine-2 HMF 70:30 623 0.47 .sup.1)Amino acid polymer The above results in Table 6 show that the ratio of amino acid polymer (polylysine) to polyaldehyde (HMF) may be varied. Preferred is a ratio of less than 70:30, but preferably not less than 50:50.

[0261] The following Examples 22 to 27 (all according to the invention) pertain to the manufacture of single-layered chipboards with Polylysine-2 and different weights of HMF (by pressing in a high-frequency press). Certain information on the components used for preparing the binder compositions of examples 22 to 27 and on certain parameters measured of resulting single-layer chipboards are shown in Tables 7 and 8 below.

[0262] In a mixer, a mixture of an amount x2 of Polylysine-2 solution (50 wt.-% in water), an amount y2 of HMF solution (50 wt.-% HMF in water) and 100 g of water, was sprayed onto 5.55 kg (5.40 kg dry weight) of spruce core layer chips (moisture content 2.8%) while mixing. After addition of the mixture, mixing was continued for 3 min.

TABLE-US-00008 TABLE 7 amount x2 of Polylysine-2 solution and amount y2 of HMF solution Amount of Polylysine- 2 solution Amount of HMF solution (50 wt.-% in water) (50 wt.-% in water) Example x2 [g] y2 [g] 22 583 64.5 23 518 130 24 486 162 25 454 194 26 421 227 27 389 259

Examples 22 to 27: Pressing the Resinated Chips to Chipboards in a High-Frequency Press

[0263] Immediately after resination, 600 g of the resinated chips were scattered into a 30x30 cm mold and pre-compacted under ambient conditions (0.4 N/mm.sup.2). Subsequently, the prepressed chip mat thus obtained was removed from the mold. For temperature monitoring a temperature sensor (GaAs chip) was introduced into the center of said pre-compacted chip mat. Nonwoven separators were then provided to the upper and lower side of the pre-compacted chip mat. The pre-compacted chip mat was inserted in a HLOP 170 press from Hoefer Presstechnik GmbH, whereby a birch plywood (thickness 6 mm) was placed between the nonwoven separator and the press plate on each side of the mat. The pre-compacted chip mat was then compacted to 10 mm thickness in the press within a period of 2 s, and then heated by applying a high-frequency electrical field (27.12 MHz, anode current 2.5 A) while the press was remaining closed. When the target temperature 130 C. was reached in the center of the pressed mat (130 C. was reached after 7515 sec), the press was opened.

TABLE-US-00009 TABLE 8 Single-layered chipboards (high-frequency press), 10 mm, binder amount (components A + B): 6 wt.-% (solids/dry wood), mixed application Component Weight ratio Density, Internal bond, Example A.sup.1) HMF A:HMF [kg/m.sup.3] [N/mm.sup.2] 22 Polylysine-2 HMF 90:10 603 0.40 23 Polylysine-2 HMF 80:20 613 0.52 24 Polylysine-2 HMF 75:25 621 0.58 25 Polylysine-2 HMF 70:30 620 0.59 26 Polylysine-2 HMF 65:35 623 0.56 27 Polylysine-2 HMF 60:40 618 0.49 .sup.1)Amino acid polymer