COMPOSITE PRODUCTS

Abstract

A sugar-based binder composition for manufacturing a composite product, notably a wood board, comprises at least one further particulate additive selected from the group consisting of:—particulate additive(s) having a BET specific surface area which is ≥50 m.sup.2/g;—amorphous silica particles;—fumed silica particles; and—untreated fumed silica particles.

Claims

1.-26. (canceled)

27. A method of manufacturing plywood comprising a stack of individual veneers, the method comprising: applying a binder composition in the form of an aqueous solution to one or more of the individual veneers to provide one or more individual resinated veneers, arranging the one or more individual resinated veneers in the stack of individual veneers wherein the direction of the grain in adjacent veneers is offset at right angles; and subjecting the stack to heat and pressure to cure the binder composition to form the plywood; wherein the binder composition is a sugar-based binder composition which comprises: polymerizable reactants, wherein at least 50% by dry weight of the polymerizable reactants comprise reactants selected from: i) one or more reducing sugar reactants; ii) one or more reactants which under curing conditions will generate one or more reducing sugar reactants; iii) curable reaction product(s) of one or more reducing sugar reactant(s); iv) reactants which under curing conditions will react with the one or more reducing sugar reactants; and v) combinations of the aforementioned reactants;—optional fillers, and at least one further particulate additive wherein the at least one further particulate additive comprises fumed silica particles.

28. A method of manufacturing a wood board, comprising: applying a binder composition in the form of an aqueous solution to loose wood matter to provide resinated loose wood matter, 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 binder composition is a sugar-based binder composition which comprises: polymerizable reactants, wherein at least 50% by dry weight of the polymerizable reactants comprise reactants selected from: i) one or more reducing sugar reactants; ii) one or more reactants which under curing conditions will generate one or more reducing sugar reactants; iii) curable reaction product(s) of one or more reducing sugar reactant(s); iv) reactants which under curing conditions will react with the one or more reducing sugar reactants; and v) combinations of the aforementioned reactants;—optional fillers, and at least one further particulate additive selected from the group consisting of: particulate additive(s) having a BET specific surface area which is ≥50 m.sup.2/g as measured in accordance with the ISO 9277 standard; synthetic amorphous silica particles; fumed silica particles; and untreated fumed silica particles.

29. The method of claim 28, wherein the polymerizable reactants consist essentially of Maillard reactant(s) and comprise: the one or more reducing sugar reactants and/or the curable reaction product(s) of one or more reducing sugar reactant(s); and one or more nitrogen containing reactants.

30. The method of claim 28, wherein the at least one further particulate additive is a particulate additive having a BET specific surface area which is ≥50 m.sup.2/g.

31. The method of claim 30, wherein the at least one further particulate additive has a BET specific surface area which is ≤600 m.sup.2/g.

32. The method of claim 28, wherein the at least one further particulate additive is a particulate additive having a mean primary particle size which is ≥5 nm and ≤100 nm.

33. The method of claim 28, wherein the at least one further particulate additive comprises synthetic amorphous silica particles.

34. The method of claim 28, wherein the at least one further particulate additive comprises untreated fumed silica.

35. The method of claim 28, wherein the at least one further particulate additive comprises hydrophilic particles.

36. The method of claim 28, wherein the sugar-based binder composition comprises: a) at least 1 wt % of the at least one further particulate additive by dry weight of the sugar-based binder composition; and/or b) no more than 15 wt % of the at least one further particulate additive by dry weight of the sugar-based binder composition.

37. The method of claim 28, wherein the at least one reducing sugar reactant is selected from the group consisting of xylose, dextrose, fructose and combinations thereof.

38. The method of claim 28, wherein the polymerizable reactants comprise at least one reducing sugar reactant and at least one nitrogen-containing reactant.

39. The method of claim 28, wherein the polymerizable reactants comprise curable reaction product(s) of at least one reducing sugar reactant and at least one nitrogen-containing reactant.

40. The method of claim 29, wherein the at least one nitrogen-containing reactant comprises polyprimary polyamine(s) selected from the group consisting of: diprimary diamines, 1,6-diaminohexane; triprimary triamine(s), 4-(aminomethyl)-1,8-octanediamine; and combinations thereof.

41. The method of claim 28, wherein the polymerizable reactants consist essentially of Maillard reactant(s) and comprise: the one or more reducing sugar reactants and/or the curable reaction product(s) of one or more reducing sugar reactant(s); and one or more nitrogen containing reactants; and wherein the one or more reducing sugar reactants are selected from the group consisting of xylose, dextrose, fructose and combinations thereof.

42. The method of claim 28, wherein the polymerizable reactants consist essentially of Maillard reactant(s) and comprise: the one or more reducing sugar reactants and/or the curable reaction product(s) of one or more reducing sugar reactant(s); and one or more nitrogen containing reactants; and wherein the one or more nitrogen containing reactants are selected from the group consisting of 1,6-diaminohexane, 4-(aminomethyl)-1,8-octanediamine and combinations thereof.

43. The method of claim 29, wherein the polymerizable reactants comprise between 60 wt % and 95 wt % of the at least one reducing sugar reactant and between 5 wt % and 40 wt % of the at least one nitrogen-containing reactant based on the total dry weight of the polymerizable reactants.

44. The method of claim 28, wherein the sugar-based binder composition comprises: a) at least 40 wt % of the polymerizable reactants based on the total dry weight of the binder composition; and/or b) less than 99 wt %, less than 97 wt %, less than 95 wt %, less than 90 wt %, less than 80 wt %, or less than 70 wt % of the polymerizable reactants based on the total dry weight of the binder composition.

45. The method of claim 28, wherein the sugar-based binder composition comprises between 3 wt % and 50 wt % of the optional filler(s) based on the total dry weight of the binder composition.

46. The method of claim 28, wherein the optional fillers comprise one or more fillers selected from the group consisting of almond shell flour, kaolin, calcium carbonate, and combinations thereof.

47. The method of claim 28, wherein the binder composition is applied to the loose wood matter in the form of an aqueous solution which comprises 40 to 95 wt % of solids based on the total weight of the aqueous binder composition.

48. The method of claim 28, wherein the wood boards comprise at least 70%, at least 80%, at least 90% or at least 95% by weight of wood matter.

49. The method of claim 28, wherein the wood board is selected from the group consisting of: plywood; a P4 particleboard; an oriented strand board; a hardboard (HB), a medium board (MBL or MBH), a softboard (SB), and a medium density fiber board (MDF).

50. The method of claim 28, wherein: the wood board is plywood comprising a stack of individual veneers, the loose wood matter comprises one or more of the individual veneers, the resinated wood matter comprises one or more individual resinated veneers, arranging the resinated wood matter as a sheet of loosely arranged resinated wood matter comprises arranging the resinated veneers in a stack wherein the direction of the grain in adjacent veneers is offset at right angles.

51. The method of claim 28, wherein: the wood board is wood particle board, and the loose wood matter comprises wood particles.

Description

[0102] Embodiments of the invention will now be described, by way of example only, with reference to the accompanying figures of which:

[0103] FIG. 1 show a plywood made with a control binder composition and a plywood made with a binder composition comprising fumed silica, each being shown after tapered sanding to reveal binder migration

[0104] FIG. 2 is a side view of the plywood pieces shown in FIG. 1;

[0105] FIG. 3 shows an image taken with a microscope of the glue line of a tapered sanding plywood made with a control binder composition;

[0106] FIG. 4 shows an image taken with a microscope of the glue line of a tapered sanding plywood made with a binder composition comprising fumed silica;

[0107] FIG. 5 shows an image taken with a microscope of the interface between cellulosic matter and cured binder for a plywood made with a binder composition comprising fumed silica;

[0108] FIG. 6 is a photograph of cured binder obtained after two hours of curing for a control binder composition and a binder composition comprising fumed silica; and

[0109] FIG. 7 is a photograph of a drop of an aqueous control binder composition and a drop of an aqueous binder composition comprising fumed silica on a poplar plywood face veneer after two hours.

EXAMPLE 1

[0110] Examples A1 and A2 are binder compositions in accordance with the invention, wherein the binder composition comprises fumed silica (Silicon (IV) Oxide from Alfa Aesar, having a surface area between 130 to 170 m.sup.2/g and an average particle size of 12 nm) as the further particulate additive. Examples C1 and C2 are control binder compositions. The proportions of the different components are given in weight % based on the total aqueous weight of the sugar-based binder compositions as shown in Table 1. Proportions of the optional fillers and type of fillers used were adjusted in order to obtain binder composition with and without fumed silica for each type of nitrogen-containing reactant with similar viscosities.

TABLE-US-00001 TABLE 1 Binder Further composition particulate (solid content additive Poly- of the Fillers Fumed merizable aqueous Almond Kaolin Calcium silica reactants binder shell flour (weight carbonate (weight (weight composition) (weight %) %) (weight %) %) %) A1 (78.9%) 0 23.8 0 5.9 49.2 C1 (80.5%) 15 15 5 0 45.5 A2 (80.4%) 0 29.4 0 5.5 45.5 C2 (83.9%) 15 15 5 0 48.9

TABLE-US-00002 TABLE 2 Dry weight Solid ratio of content of nitrogen reducing sugar the aqueous Binder con- reactants poly- com- taining reducing sugar to nitrogen merizable position reactant reactants containing reactant reactants A1 AMOD 50% Glu + 50% Fru 70:30 70% C1 AMOD 50% Glu + 50% Fru 70:30 70% A2 HMDA 50% Glu + 50% Fru 70:30 70% C2 HMDA 50% Glu + 50% Fru 70:30 77% Key: Glu = glucose; Fru = fructose; AMOD = 4-(aminomethyl)-1,8-octanediamine; HMDA = 1,6-diaminohexane. For AMOD used in A1 and C1, the purity is around 93-98%. For HMDA used in A2 and C2, the solution used is a 70% solids solution

[0111] Each of the binder compositions was prepared by combining the nitrogen containing component and the reducing sugar reactants in water in the proportions given in Table 2 to obtain a solution/dispersion of the polymerizable reactants. The optional fillers (herein almond shell flour, kaolin and calcium carbonate) and the fumed silica further particular additive were mixed with the aqueous solution/dispersion of the polymerizable reactants in the proportions given in the above Table 1. Then each binder composition was used to produce 5-ply plywood panels with the parameters set out in Table 3.

TABLE-US-00003 TABLE 3 Panel Press Press Target dimensions temperature pressure Duration of Wood glue dose (mm) (° C.) (MPa) press species (g/m.sup.2) 390 × 390 × 10 140 0.464 7 min 15 sec Poplar 150

[0112] The shear strengths were measured in accordance with ASTM D 906-98 (2004). Two horizontal 12.9 cm strips were cut from each plywood panel manufactured. Then each strip was routed on both sides to a set depth to provide the notches required for the test. Twelve 2.5 cm samples from each of these strips were cut. The sample were then soaked in water at 20±3° C. for 24 hours. The samples were then immediately placed into the testometric machine and shear strength (pulled closed (compression) shear strength as defined in the ASTM D 906-98 standard) was measured. The results of the median of the shear strengths are given in the Table 4 below.

TABLE-US-00004 TABLE 4 Binder composition Median shear strength (pulled used closed (compression)) for the plywood (N/mm.sup.2) A1 1.47 C1 1.29 A2 1.10 C2 0.94

[0113] The results show that using binder compositions A1 and A2 comprising fumed silica gives better shear strengths (pulled closed (compression)) compared to using binder compositions C1 and C2 without fumed silica.

[0114] No bleedthrough was observed for the plywood made with the binder compositions A1 and A2.

EXAMPLE 2

Binder Migration

[0115] To evaluate binder migration, 5-ply plywood panels were produced with the panel parameters shown in Table 3 with binder compositions A1 and C1 as shown in Tables 1 and 2. The fumed silica used is the fumed silica as defined in Example 1.

[0116] Binder migration was evaluated in accordance with the following protocol. A sanded gradient through the surface veneer into the glue line and through to the interior veneer was produced by sanding one of the major surfaces of each piece of plywood in a gradient from one side of the plywood to the other and breaking into the glue line near the deepest point. The back of the panel is lightly sanded to smooth out localised variations in wood thickness. This reveals a snapshot of the binder bleedthrough across the panel piece. Then one point on each side of the panel is taken (avoiding the centre third) where there is the longest distance between the glueline and clearly visible bleedthrough at the surface at that point, and this is marked. Then the thickness is measured at this point to determine the maximum observable thickness that the binder has travelled. The difference of these thicknesses is taken compared to the corresponding thickness at the glueline and that is the distance the binder is considered to have migrated. It is used comparatively to assess the bleedthrough performance of various binder compositions. The measurement was made on eight samples. FIGS. 1 and 2 show, after sanding: a) on the left-hand side plywood made with control binder composition C1 and b) on the right hand side plywood made with binder composition A1 comprising fumed silica.

[0117] The median results of the binder migration are given in Table 5 below.

TABLE-US-00005 TABLE 5 Binder composition used Median binder for the plywood migration (mm) A1 0.23 C1 0.65

[0118] The results show that less binder migration was observed with the binder composition A1 comprising fumed silica compared to the binder composition C1 without fumed silica.

EXAMPLE 3

Tapered Sanding—Microscopic Photos

[0119] Photographs of the tapered sanding plywood produced in Example 2 are presented in FIGS. 3, 4 and 5; the photographs were taken using a microscope at a magnification of about 100.

[0120] FIG. 3 shows the glue line of a plywood made with the control binder composition C1.

[0121] FIG. 4 shows the glue line of a plywood made with the binder composition A1.

[0122] FIG. 5 shows the interface between cellulosic matter and cured binder for a plywood made with the binder composition A1.

[0123] As can be seen in FIG. 3, the binder composition C1 seems to have at least partially penetrated into the cellulosic matter and/or has significantly migrated within the plywood. It is thus believed that a reduced amount of binder is present at the actual glue line to “bind” the cellulosic matter.

[0124] In comparison, in FIG. 4 very little cellulosic matter is observed since the binder composition has not penetrated within the cellulosic matter nor migrated and therefore the majority of the binder composition applied remains present at the actual glue line and is thus available to bind together the cellulosic matter of adjacent plies of the plywood.

[0125] As can be seen in FIG. 5 at the interface between the cellulosic matter and the cured binder, substantially none of the binder composition has been absorbed within the cellulosic matter.

EXAMPLE 4

Spreading of the Binder Composition

[0126] Example A4 is a binder composition in accordance with the invention, wherein the binder composition comprises fumed silica (Silicon(IV) Oxide from Alfa Aesar, having a surface area between 130 to 170 m.sup.2/g and an mean primary particle size of 12 nm). Example C4 is a control binder composition. The proportions of the different components are given in weight % based on the total weight of the aqueous sugar-based binder composition as shown in Table 6. Proportions of the optional fillers and type of fillers used were adjusted in order to obtain binder composition with similar viscosities.

TABLE-US-00006 TABLE 6 Binder Further composition particulate (solid additive Poly- content of Fillers Fumed merizable the aqueous Almond Kaolin Calcium silica reactants binder shell flour (weight carbonate (weight (weight composition) (weight %) %) (weight %) %) %) A4 (79.4%) 0 23.5 0 7.8 48.0 C4 (80.5%) 15 15 5 0 45.5

TABLE-US-00007 TABLE 7 Dry weight Solid ratio of content of Reducing sugar the reactants aqueous Binder nitrogen to nitrogen poly- com- containing reducing sugar containing merizable position reactant reactants reactant reactants A4 AMOD 50% Glu + 50% Fru 70:30 70% C4 AMOD 50% Glu + 50% Fru 70:30 70% Key: Glu = glucose; Fru = fructose; AMOD = 4-(aminomethyl)-1,8-octanediamine. For AMOD used in A4 and C4, the purity is around 93-98%.

[0127] Each of the binder compositions was prepared by combining the nitrogen containing component and the reducing sugar reactant in water in the proportions given in Table 7 to obtain a solution/dispersion of the polymerizable reactants. The optional fillers (herein almond shell flour, kaolin and calcium carbonate) and fumed silica were mixed with the aqueous solution/dispersion of the polymerizable reactants in the proportions given in Table 6.

[0128] A mass of each of binder compositions C4 and A4 was applied to a metal tray and placed in an oven for 2 hours at 140° C. FIG. 6 is a photograph of the cured binder C4 (shown on the left-hand side) and cured binder A4 (shown on the right-hand side) obtained after the two hours of curing the binder compositions in the oven. As can be seen, cured binder composition A4 comprising fumed silica is more “compacted” than cured binder composition C4. In the cured binder composition C4, many “holes” having the appearance of foamed cells are visible; it is believed that this explains the greater spreading of binder composition C4.

[0129] FIG. 7 is a photograph of a drop of each aqueous binder composition A4 (shown on the left-hand side) and C4 (shown on the right-hand side) applied to a poplar plywood face veneer. The photograph was taken 2 hours after the deposition of the drop on the wood. As can be seen, the contact angle of the drop of the two binder compositions is clearly different. The drop of the aqueous binder composition C4 has already started to penetrate into the wood, while the drop of the aqueous binder composition A4 is still intact.

EXAMPLE 5

Binder Migration

[0130] Example A5 is a binder composition in accordance with the invention, wherein the binder composition comprises fumed silica having a surface area between 130 to 170 m.sup.2/g (Silicon(IV) Oxide from Alfa Aesar, mean primary particle size of 12 nm) and example A6 is a binder composition in accordance with the invention wherein the binder composition comprised fumed silica having a surface area between 175 to 225 m.sup.2/g (CAB-O-SIL® M5 from Cabot). Example C5 is a control binder composition. The proportions of the different components are given in weight % based on the total weight of the aqueous sugar-based binder composition as shown in Table 8.

TABLE-US-00008 TABLE 8 Binder composition (solid Filler Further particulate Polymerizable content of the aqueous Kaolin additive Fumed reactants binder composition) (weight %) silica (weight %) (weight %) A5 (78.9%) 23.8 5.9 49.2 A6 (78.9%) 23.8 5.9 49.2 C5 (78.9%) 29.7 0 49.2

TABLE-US-00009 TABLE 9 Dry weight ratio of Solid content of Binder nitrogen reducing Reducing sugar the aqueous com- containing sugar reactants to nitrogen polymerizable position reactant reactants containing reactant reactants A5 AMOD HFCS 70:30 70% A6 AMOD HFCS 70:30 70% C5 AMOD HFCS 70:30 70% Key: HFCS = High Fructose Corn Syrup; AMOD = 4-(aminomethyl)-1,8-octanediamine, the purity is around 93-98%.

[0131] Each of the binder compositions was prepared by combining the nitrogen containing component and the reducing sugar reactant in water in the proportions given in Table 9 to obtain a solution/dispersion of the polymerizable reactants. The optional filler (herein kaolin) and fumed silica were mixed with the aqueous solution/dispersion of the polymerizable reactants in the proportions given in Table 8. Then each binder composition was used to produce 5-ply plywood panels with the parameters set out in Table 10.

TABLE-US-00010 TABLE 10 Panel Press Press Duration dimensions temperature pressure of Wood Target glue (mm) (° C.) (MPa) press species dose (g/m.sup.2) 390 × 390 × 10 120 0.464 5 min Poplar 150

[0132] Binder migration was evaluated in accordance with the protocol as defined in Example 2.

[0133] The median results of the binder migration are given in Table 11 below.

TABLE-US-00011 TABLE 11 Binder composition used Median binder for the plywood migration (mm) A5 0.27 A6 0.39 C5 0.56

[0134] The results show that less binder migration was observed with the binder compositions A5 and A6 comprising fumed silica compared to the binder composition C5 without fumed silica. Less binder migration was observed with the binder composition A5 than with binder composition A6.