WOOD BOARDS

Abstract

A method of manufacturing a wood board, comprising: - applying a binder composition, notably in the form of an aqueous solution, to loose wood matter to provide resinated loose wood matter, wherein the binder composition consists of a binder composition prepared by combining reactants comprising at least 50% by dry weight reducing sugar reactant(s) and at least 5% by dry weight nitrogen-containing reactant(s); and—arranging the resinated wood matter as a sheet of loosely arranged resinated wood matter; and—subjecting the sheet of loosely arranged resinated wood matter to heat and pressure to cure the binder composition and to form the wood board from the sheet of loosely arranged resinated wood;—wherein the nitrogen-containing reactant(s) comprise TPTA triprimary triamine(s), notably wherein the nitrogen-containing reactant(s) comprise at least 5% by dry weight of TPTA triprimary triamine(s).

Claims

1. A method of manufacturing a wood particle board, comprising: applying a binder composition in the form of an aqueous solution to loose wood matter to provide resinated loose wood matter, wherein the binder composition consists of a binder composition prepared by combining reactants comprising at least 50% by dry weight reducing sugar reactant(s) and at least 5% by dry weight nitrogen-containing reactant(s); and arranging the resinated wood matter as a sheet of loosely arranged resinated wood matter; and subjecting the sheet of loosely arranged resinated wood matter to heat and pressure to cure the binder composition and to form the wood board from the sheet of loosely arranged resinated wood; wherein the nitrogen-containing reactant(s) comprise at least 5% by dry weight of TPTA triprimary triamine(s), the TPTA triprimary triamine(s) being organic compound(s) having three and only three amines, each of the amines being primary amines or salts thereof, selected from: a) triprimary triamine(s) having spacer groups between each of the three primary amines which consist of carbon chains; b) triprimary triamine(s) having spacer groups between each of the three primary amines wherein each spacer group has a spacer length which is less than or equal to 12 polyvalent atoms; and c) triprimary triamine(s) having a total number of polyvalent atoms which is less than or equal to 23.

2. A method according to claim 1, wherein the reducing sugar reactant(s) comprise reducing sugar reactant(s) selected from the group consisting of xylose, dextrose, fructose and combinations thereof.

3. A method according to claim 1, wherein the TPTA triprimary triamine(s) consist of triprimary triamine(s) having spacer groups between each of the three primary amines which consist of carbon chains.

4. A method according to claim 1, wherein the nitrogen-containing reactant(s) comprise triprimary triamine(s) selected from the group consisting of triaminodecanes, triaminononanes, triaminooctanes, triaminoheptanes, triaminohexanes, triaminopentanes, and combinations thereof.

5. A method according to claim 1, wherein the nitrogen-containing reactant(s) comprise 4-(aminomethyl)-1,8-octanediamine.

6. A method according to claim 1, wherein the binder composition consists of a binder composition prepared by combining reactants consisting of between 60% and 95% by dry weight reducing sugar reactant(s) and between 5% and 40% by dry weight nitrogen-containing reactant(s).

7. A method according to claim 1, wherein the nitrogen-containing reactant(s) comprise at least 95 wt % of TPTA triprimary triamine(s).

8. A method according to claim 1, wherein the nitrogen-containing reactants comprise reactant(s) different from the TPTA triprimary triamine(s) selected from the group consisting of 1,6-diaminohexane, 1,5-diamino-2-methylpentane, and combinations thereof.

9. A method according to claim 1, wherein the nitrogen-containing reactants comprise reactant(s) different from the TPTA triprimary triamine(s), wherein the. nitrogen containing reactants comprise inorganic or organic ammonium salt selected from the group consisting of ammonium sulfate, ammonium phosphate, ammonium citrate, and combinations thereof.

10. A method according to claim 1, wherein the binder composition is applied to the loose wood matter in the form of an aqueous solution which comprises 40 to 95 wt %, 45 to 90 wt %, 50 to 85 wt %, or 55 to 80 wt % of solids, based on the total weight of the aqueous binder composition.

11. A method according to claim 1, wherein the binder composition is applied to the loose wood matter in the form of an aqueous solution which is prepared by combining all the reducing sugar reactant(s) and all the nitrogen-containing reactant(s) in a single preparation step.

12. A method according to claim 1, wherein the binder composition is applied to the loose wood matter in the form of an aqueous solution which is prepared by combining all of the reducing sugar reactant(s) with a first portion of the nitrogen-containing reactant(s) to provide an intermediate binder composition comprising reaction products of the reducing sugar reactant(s) and the first portion of the nitrogen-containing reactant(s), storing the intermediate binder composition; and combining the intermediate binder composition with a second portion of the nitrogen-containing reactant(s) to provide the binder composition.

13. A method according to claim 1, wherein, in the form in which it is applied to the wood matter, the binder composition consists essentially of curable reaction product(s) of the reducing sugar reactant(s) and the nitrogen-containing reactant(s).

14. A wood board produced in accordance with the method of claim 1.

15. A wood board comprising wood matter held together by a cured thermoset binder, wherein the thermoset binder composition comprises a polymeric product of reducing sugar reactant(s) and nitrogen-containing reactant(s) and wherein the nitrogen-containing reactant(s) comprise triprimary triamine(s), the triprimary triamine(s) being organic compound(s) having three and only three amines, each of the amines being primary amines or salts thereof, having spacer groups between each of the three primary amines which consist of carbon chains, wherein the nitrogen-containing reactant(s) consist of 4-(aminomethyl)-1,8-octanediamine.

Description

[0097] Embodiments of the invention will now be described, by way of example only, with reference to the accompanying figures of which:

[0098] FIGS. 1 and 2 show surface soundness results;

[0099] FIGS. 3 and 4 show 24 h water swelling results;

[0100] FIGS. 5 and 6 show internal bond strength results;

[0101] FIG. 7 shows 4-(aminomethyl)-1,8-octanediamine (“AMOD”);

[0102] FIG. 8 shows cure results of a laboratory cure test of triprimary polyamines;

[0103] FIG. 9 shows a blow crack formed on a wood board made using TAEA as the nitrogen-containing reactant with a press time of 90 s;

[0104] FIG. 10 shows a wood board made using AMOD as the nitrogen-containing reactant with a press time of 90 s; and

[0105] FIG. 11 shows an example of TPTA triprimary triamine.

EXAMPLE 1

Wood Particles Boards

[0106] Wood particle boards are commonly manufactured using urea formaldehyde binders. The following compares:

[0107] Examples B1, B2, B3, B4, B5 and B6 which are laboratory manufactured three layer wood particle boards in accordance with the invention; with

[0108] Comparative examples C1, C2, C3, C4, C5 and C6 which are laboratory manufactured three layer wood particle boards manufactured using a common urea formaldehyde binder.

[0109] The laboratory manufactured particle boards described herein were manufactured contemporaneously in a way to enable comparison between them. Laboratory conditions and results are not necessarily directly comparable with results that would be obtained during industrial manufacture of particle boards. For example: results obtained using a binder loading of 8 wt % in the laboratory may be hoped to be achieved using a binder loading of 3-4 wt % during industrial manufacture; a press time of 7 s/mm in the laboratory may be required to simulate what could be hoped for using a press time of 4.5 s/mm during industrial manufacture; 24 h water swelling of 30% in the laboratory may provide an indication that a 24 h water swelling of 15% could be hoped for during industrial manufacture. Similarly, the present laboratory results may not be directly comparable with other laboratory results for example which use different methods, conditions, wood particles or equipment.

[0110] For the measurements conducted: [0111] surface soundness was tested in accordance with EN 311:2002. A circular groove (inner diameter of 35.7 mm) is cut 0.3 mm deep into the test sample. A steel pad is glued onto the board surface, on the cut surface portion. After the adhesive has hardened a tensile force is applied at constant speed so that failure occurs, preferably within the surface layer; the force at failure is recorded and expressed in Newtons per square millimeter. [0112] swelling was measured in accordance with EN 317:1993. [0113] internal bond strength (IB) was tested in accordance with EN 319:1993; this is intended to evaluate the tensile strength perpendicular to the plane of the test piece and expressed in N/mm.sup.2.

[0114] Each of the examples B1, B2, B3, B4, B5 and B6 and comparative examples C1, C2, C3, C4, C5 and C6 was a three-layer particle board having: [0115] a length and width of about 300×300 mm; [0116] a pressed thickness of about 16 mm; [0117] a density of about 650 kg/m.sup.3; and [0118] a core:surface wood chip mass ratio 62:38; prepared by [0119] spraying a binder composition on to oven dried wood particles having a residual moisture content of about 3.5 wt % and thoroughly mixing; [0120] assembling the resinated wood particles into a resinated mat of loosely arranged resinated wood particles; and [0121] pressing the mat of loosely arranged resinated wood particles between heated plates of a press (pressure 56 bar; target plate temperature 180° C.); to cure the binder composition and to form the wood particle board. The binders and press factors are described below. The same core type particles were used for each core and the same surface type particles were used for each surface layer, with the average particle size of the surface type particles being smaller than that of the core type particles.

[0122] Comparative examples C1, C2, C3, C4, C5 and C6 were produced using a commonly used urea formaldehyde binder available from Dynea under reference 10F102 using: [0123] a) for the core layer binder composition: [0124] a binder loading of 7.5 wt % on the wood particles; [0125] an ammonium nitrate catalyst with the binder at a solids ratio of 4.5:95.5 by weight catalyst: urea formaldehyde resin; and [0126] b) for the surface layer binder composition: [0127] a binder loading of 10 wt % on the wood particles; [0128] an ammonium nitrate catalyst with the binder at a solids ratio of 0.5:99.5 by weight catalyst: urea formaldehyde resin.

[0129] Examples B1, B2, B3, B4, B5 and B6 were produced with the following binder compositions: [0130] a) for the core layer binder composition: [0131] a binder composition prepared by combining reactants consisting of 69% by dry weight reducing sugar reactants and 31% by dry weight nitrogen-containing reactant where i) the reducing sugar reactants consisted of 50 wt % fructose and 50 wt % dextrose monohydrate; and the nitrogen-containing reactant consisted of 4-(aminomethyl)-1,8-octanediamine; [0132] a binder loading of 7.5 wt % on the wood particles; and [0133] b) for the surface layer binder composition: [0134] a binder composition prepared by combining reactants consisting of 79.2% by dry weight reducing sugar reactants and 20.8% by dry weight nitrogen-containing reactant where i) the reducing sugar reactants consisted of 50 wt % fructose and 50 wt % dextrose monohydrate; and the nitrogen-containing reactant consisted of 4-(aminomethyl)-1,8-octanediamine; [0135] a binder loading of 8 wt % on the wood particles.

[0136] Boards B1 and C1 were each cured at a press factor of 10 s/mm. FIG. 1 shows a higher surface soundness for board B1 (about 1.4 N/mm.sup.2) compared with board C1 (about 0.9 N/mm.sup.2);

[0137] Each of boards B2 and C2 was cured at a press factor of 8 s/mm. FIG. 2 shows a higher surface soundness for board B2 (about 1.3 N/mm.sup.2) compared with board C2 (about 0.8 N/mm.sup.2).

[0138] It is notable that higher surface soundness of B1 and B2 was achieved with a binder loading of 8 wt % in the surface layer compared with a surface layer binder loading of 10 wt % for C1 and C2.

[0139] Boards B3 and C3 were each cured at a press factor of 10 s/mm. FIG. 3 shows a lower 24 h water swelling for board B3 (about 23%) compared with board C3 (about 27%). Each of boards B4 and C4 was cured at a press factor of 8 s/mm. FIG. 4 shows a lower 24 h water swelling for board B4 (about 25%) compared with board C4 (about 30%). It is again notable that B3 and B4 show such improvement of 24h water swelling compared to C3 and C4 despite the binder loading of the surface layer for C3 and C4 being 10 wt % and the binder loading of the surface layer of B3 and B4 being only of 8 wt %.

[0140] Boards B5 and C5 were each cured at a press factor of 10 s/mm. FIG. 5 shows a higher internal bond strength for board B5 (about 0.8 N/mm.sup.2) compared with board C5 (about 0.5 N/mm.sup.2).

[0141] Each of boards B6 and C6 was cured at a press factor of 8 s/mm. FIG. 6 shows a higher internal bond strength for board B6 (about 0.7 N/mm.sup.2) compared with board C6 (about 0.4 N/mm.sup.2).

EXAMPLE 2

Laboratory Indication of Cure Speed With HFCS

[0142] The following binder compositions were prepared by combining a nitrogen containing reactant and a reducing sugar reactant

TABLE-US-00005 Binder % dry composition nitrogen containing reactant weight Notes 1a AMOD (4-(aminomethyl)-1, 22.5% a TPTA 8-octanediamine triprimary triamine 1b TAPA (tris(3-aminopropyl)amine) 24.0% a triprimary tetramine 1c TAEA (tris(2-aminoethyl)amine) 19.7% a triprimary tetramine

[0143] The nitrogen containing reactants of binder compositions 1b and 1c are not TPTA triprimary triamines and thus provide comparative examples. Each of the binder compositions was prepared by combining the nitrogen containing reactant with HFCS 42 (high fructose corn syrup with 42% fructose+52% dextrose+trace quantities of other saccharides) in water to obtain a solution/dispersion containing 1 molar equivalent of triprimary polyamine to 3.31 molar equivalents of reducing sugars. The amounts of triprimary polyamines used in the binder compositions are expressed above and in FIG. 8 as dry weight % (the remaining dry weight being the HFCS 42) and the binder compositions were prepared at 22.5% total solids weight. Each binder composition was formulated to give a primary amine to carbonyl molar ratio on 1:1.105. FIG. 8 shows the light absorbance of leachates from glass fiber filters: drops of the binder compositions were applied to the glass fiber filters which were then were placed in an oven at 107° C. and subsequently removed after set time intervals. Brown polymers were formed on the filters, then dissolved in water and the absorbance of the leachate measured using a spectrophotometer. The evolution of the formation of soluble brown polymers and insoluble polymers provides an initial laboratory indication of curing and cure speed for these type of binders.

[0144] FIG. 8 shows that binder composition 1a using AMOD (4-(aminomethyl)-1,8-octanediamine, a TPTA triprimary triamine) shows a faster curing rate compared to binder composition 1b using TAPA (tris(3-aminopropyl)amine) and binder composition 1c using TAEA (tris(2-aminoethyl)amine) which are both triprimary tetramines.

EXAMPLE 3

Particle Board

[0145] Single layer particleboard were prepared using AMOD (4-(aminomethyl)-1,8-octanediamine) or TAEA (tris(2-aminoethyl)amine)) as the sole nitrogen-containing reactant in a binder composition using a mixture of glucose and fructose as the reducing sugar reactant. The amounts of the reactants used in the binder compositions are expressed in Table 5 as dry weight % and the binder compositions were prepared at 70% total solids weight. The binder compositions were formulated to obtain a solution/dispersion containing 1 molar equivalent of triprimary polyamine to 2.25 molar equivalent of reducing sugars (primary amine to carbonyl mole ratio of 1:0.75). The boards (300×300×10 mm, 7.5% binder loading) were pressed (504 N at 195° C.) for 90 seconds, 100 seconds and 120 seconds). The internal bond strength (IB) was tested in accordance with EN 319:1993; the swelling test was performed in accordance with EN 317:1993.

[0146] For the press time of 90 s, the board made using TAEA as the nitrogen-containing reactant developed a blow crack when released from the press (see FIG. 9); this type of defect is typically caused by insufficient cure of the binder composition. However, the board prepared using AMOD as the nitrogen-containing reactant had sufficiently cured at a time press of 90 s and did not form a blow crack (see FIG. 10) when released from the press.

TABLE-US-00006 TABLE 5 Press Swelling Time IB (after Binder composition (% dry weight) (sec) (N/mm.sup.2) 24 hours) 35% Glu + 35% Fru + 30% AMOD 100 1.22 30.4% 36.7% Glu + 36.7% Fru + 26.6% TAEA 100 0.92 37.7% 35% Glu + 35% Fru + 30% AMOD 120 1.20 29.7% 36.7% Glu + 36.7% Fru + 26.6% TAEA 120 0.99 37.3% Key: Glu = glucose; Fru = fructose; AMOD = 4-(aminomethyl)-1,8-octanediamine; TAEA = tris(2-aminoethyl)amine

[0147] The results show that the boards made with the binder composition with AMOD also gave a higher average IB than the boards made with the binder composition with TAEA (results based on the average of 8 tested 5 cm×5 cm×1 cm blocks). The binder composition with AMOD gave better swelling results than the binder composition with TAEA.

[0148] The subsequent examples further demonstrate advantages of TPTA triprimary triamines in laboratory tests which can be extrapolated to manufacture of wood boards.

EXAMPLE 4

[0149] Examples of binder compositions tested on mineral fiber veils are shown in Table 6 with their respective mean dry veil tensile strengths and mean wet tensile strengths.

[0150] In each case, a nitrogen containing reactant comprising a triprimary polyamine was combined with HFCS 42 (high fructose corn syrup with 42% fructose+52% dextrose+trace quantities of other saccharides) in water to obtain a solution/dispersion containing 1 molar equivalent of triprimary polyamine to 3.31 molar equivalent of reducing sugars. The amounts of triprimary polyamines used in the binder compositions are expressed in Table 6 as dry weight %, the remaining dry weight being the HFCS, and the binder compositions were prepared at 2% weight (bake out solids). Once the binder compositions were prepared, they were applied to A4 size glass veil and the glass veils were cured to obtain a quantity of cured binder in the final product of 10% LOI (loss on ignition).

[0151] Measurement of dry glass veil tensile strength:

[0152] 8 pieces of cured glass veil with a dimension of 14.8 cm×5.2 cm were cut from the cured A4 size veil and subjected to tensile testing by attaching a 50 Kg load cell using glass veil tensile plates on a testometric machine (TESTOMETRIC M350-10CT). The average of the total force in Newtons of the breaking strength is given in the table below. For the measurement of wet glass veil tensile strength, the veil samples are tested wet after being immersed in water at 80° C. for 10 minutes.

[0153] The column of wet strength % gives the % of mean wet tensile strength with respect to the % mean dry tensile strength.

TABLE-US-00007 TABLE 6 Mean Mean Triprimary polyamine dry tensile wet tensile Wet (% dry weight) strength (N) strength (N) strength % TAEA (19.7%) 73.5 25.3 31.7% TAPA (24.0%) 80.9 31.4 38.8% AMOD (22.5%) 75.3 41.4 55.0%

[0154] The results show that all the triprimary polyamines give good dry tensile strengths with TAPA giving a slightly better dry tensile strength compared to AMOD and TAEA. In regard of the wet tensile strengths, AMOD show better results compared to TAPA and TAEA. It is unexpected that the wet strength for AMOD was 55% of the value of the dry tensile strength while for TAPA it was only of 38.8%.

EXAMPLE 5

[0155] Examples of binder composition tested on mineral fiber veils are shown in Table 7 with the respective mean dry veil tensile strengths:

[0156] In each test, the nitrogen-containing reactant(s) were mixed with glucose in water. The amounts of the reactants used in the binder compositions are expressed in Table 7 as dry weight % and the binder compositions were prepared at 2% solids weight (bake out solids).

[0157] Once the binder compositions were prepared, they were applied to glass veil which were cured to obtain a quantity of cured binder in the cured veil of 10% LOI (loss on ignition). The dry tensile strength is measured in the same way as described in example 4.

TABLE-US-00008 TABLE 7 Mean dry tensile Test Ref Binder composition (% dry weight) strength (N) G (comparative) 85% Glu + 15% DAP 76.5 H (comparative) 85% Glu + 15% AS 73.5 I (comparative) 85% Glu + 15% TriCA 93.0 J 85% Glu + 15% AMOD 81.0 K 85% Glu + 5% AMOD + 10% DAP 80.0 L 85% Glu + 7.5% AMOD + 7.5% DAP 80.2 M 85% Glu + 10% AMOD + 5% DAP 82.4 N 85% Glu + 5% AMOD + 10% AS 84.7 O 85% Glu + 7.5% AMOD + 7.5% AS 90.0 P 85% Glu + 10% AMOD + 5% AS 88.6 Q 85% Glu + 5% AMOD + 10% TriCa 88.0 R 85% Glu + 7.5% AMOD + 7.5% TriCA 91.4 S 85% Glu + 10% AMOD + 5% TriCA 87.9 Key: Glu = glucose; AS = ammonium sulphate; DAP = diammonium phosphate; TriCA = triammonium citrate; AMOD = 4-(aminomethyl)-1,8-octanediamine

[0158] Binder compositions G, H and I are comparative examples of binder compositions with respectively only diammonium phosphate (DAP), ammonium sulfate (AS), and triammonium citrate (TriCa) as nitrogen-containing reactant. Binder composition J is a binder composition wherein the nitrogen-containing reactant consists of AMOD.

[0159] In examples K, L and M, the nitrogen-containing reactants consist of AMOD and DAP in different proportions. Examples J, K, L and M shows that similar levels of dry tensile strength are achieved for each of these binder compositions.

[0160] In examples N, O and P, the nitrogen-containing reactants consist of AMOD and AS in different proportions. The binder compositions N, O and P present higher dry tensile strengths compared to the result obtained with the binder composition J. Binder composition O seems to present an optimum result compared to binder compositions N and P. It is believed that there is a synergistic effect of the presence of AS and AMOD as the nitrogen-containing reactants.

[0161] FIG. 11 illustrates a TPTA triprimary triamine having three primary amines A, B, D with spacer groups which consist of carbon chains between each of its three primary amines. Each carbon atom is numbered to facilitate the explanation below.

[0162] The spacer group between primary amines A and B: [0163] has a spacer length of 7, ie carbon atoms 1, 2, 3, 4, 5, 6, 7 which together form the shortest chain of covalently bonded polyvalent atoms between primary amines A and B (the carbon atoms of the two branched chains 8, 9 and 10, 11 do not form part of the spacer length; [0164] has 11 polyvalent atoms, ie carbon atoms 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 and 11(the carbon atoms 12, 13, 14, 15, 16 do not form part of the spacer group between A and B as they form a chain which connects the third primary amine D to the molecule).

[0165] The spacer group between primary amines A and D: [0166] has a spacer length of 10, ie carbon atoms 1, 2, 3, 4, 5, 12, 13, 14, 15, 16; [0167] has 14 polyvalent atoms, ie carbon atoms 1, 2, 3, 4, 5, 8, 9, 10, 11, 12, 13, 14, 15, 16.

[0168] The spacer group between primary amines B and D: [0169] has a spacer length of 8, ie carbon atoms 7, 6, 5, 12, 13, 14, 15, 16; [0170] has 10 polyvalent atoms, ie carbon atoms 7, 6, 5, 12, 13, 14, 15, 16, 10, 11 (the chain of carbon atoms 4, 3, 2, 1, 8, 9 does not form part of the spacer group between B and D as this form a chain which connects the other primary amine A to the molecule.

[0171] The total number of polyvalent atoms in the molecule is 19, i.e. carbon atoms 1 to 16 and the 3 nitrogen atoms of the 3 primary amines A, B and D.