RECONSTITUTED WOOD PANEL WITH NATURAL WOOD GRAIN AND MANUFACTURING METHOD THEREOF

Abstract

The present invention relates to a reconstituted wood panel, and more particularly to a reconstituted wood panel with natural wood grain and manufacturing method thereof. The reconstituted wood panel with natural wood grain of the present invention is manufactured by peeling or slicing the logs to obtain veneers with thickness of 320 mm, and then impregnating with adhesive and hot pressing. The compression ratio is 10%, and the density is 0.71.3 g/cm3, and the thickness swelling rate is 3.0% and the internal bonding strength is 3.0 MPa. By comparing the sawn wood board of the same tree species, the density of the reconstituted wood panel with natural wood grain is increased by 10% or more, and the thickness swelling rate is reduced by 20% or more, and the internal bonding strength has a growth of 35% or more. The panel of the present invention is manufactured by firstly peeling or slicing to obtain thick veneer(s) with splitting injury, and then impregnating with the adhesive to repair splits of veneers. The panel has advantages of good toughness, high strength, good dimensional stability, low sawline wastage, and short drying time, high production efficiency, low energy consumption and being environmentally friendly.

Claims

1. A reconstituted wood panel with natural wood grain, characterized in that, manufactured by peeling or slicing the logs to obtain veneers with thickness of 320 mm, and then impregnating with the adhesive and hot pressing; the compression ratio of the said reconstituted wood panel being 10%; the said reconstituted wood panel being tested according to GB/T 17657-2013 Test methods of evaluating the properties of wood-based panels and surface decorated wood-based panels and LY/T 1984-2011 Reconstituted wood flooring, and the density being 0.71.3 g/cm.sup.3, and the thickness swelling rate being 3.0% and the internal bonding strength being 3.0 MPa; by comparing testing results of the said reconstituted wood panel and the sawn wood board of the same tree species in accordance with GB/T 17657-2013 Test methods of evaluating the properties of wood-based panels and surface decorated wood-based panels and LY/T 1984-2011 Reconstituted wood flooring, the density being increased by 10% or more, and the thickness swelling rate being reduced by 20% or more, and the internal bonding strength being increased by 35% or more.

2. A manufacturing method of the said reconstituted wood panel with natural wood grain according to claim 1, comprising the following steps: a. peeling or slicing the logs to obtain Veneer A with thickness of 320 mm, which has splitting injury or injuries; b. drying said Veneer A; c impregnating said Veneer A with the adhesive; and d. repairing the splits of said Veneer A; wherein, the said splits repairing process is specifically: firstly, lateral pressuring the Veneer A to make longitudinal or oblique splits to be closed or mostly closed in the width direction of Veneer A, and to repair most of the longitudinal splits and the longitudinal portion of the oblique splits; then, hot pressing Veneer A up and down in the vertical direction to eliminate the transverse or oblique splits in the thickness direction of Veneer A, and to repair the transverse splits and the transverse portion of the oblique splits, and simultaneously repair the longitudinal splits and the longitudinal portion of the oblique splits; and continuing hot pressing to reduce the thickness, and improve the density of Veneer A; and then maintaining the pressure and temperature to make the adhesive impregnating into the Veneer A being completely cured and make the repaired splits being solid, and then obtaining the said reconstituted wood panel with natural wood grain, which has stable properties.

3. The manufacturing method of reconstituted wood panel with natural wood grain according to claim 2, wherein, in step a, peeling or slicing the logs to obtain Veneer A with thickness of 320 mm, which has splitting injury or injuries; the drying in step b is to control the moisture content of Veneer A to 715%; in step c, the said adhesive is one of the water soluble phenolic resin glue, water soluble urea-formaldehyde resin glue, polyurethane glue or the mixed liquid of the water soluble phenolic resin glue and the nitrile rubber emulsion.

4. The manufacturing method of reconstituted wood panel with natural wood grain according to claim 3, wherein, in step b, a continuous conveying dryer is used for rapid drying at the drying temperature of 75120 C. and the drying time of 60300 min, in order to control the moisture content of Veneer A to 715%.

5. The manufacturing method of reconstituted wood panel with natural wood grain according to claim 3, wherein, in the said mixed liquid of water soluble phenolic resin and nitrile rubber emulsion, the nitrile rubber emulsion accounts for 515% by weight of water soluble phenolic resin in which the solids content is 45%.

6. The manufacturing method of reconstituted wood panel with natural wood grain according to claim 3, wherein, in step d, the method of constant mold width is used when repairing the longitudinal splits and the longitudinal portion of the oblique splits; the method of constant mold thickness is employed when repairing the transverse splits and the transverse portion of the oblique splits.

7. The manufacturing method of reconstituted wood panel with natural wood grain according to claim 3, wherein, in step d, placing one or more Veneer(s) A in the mold frame, a presser is used to compress one or more Veneer(s) A by two-sides or one-side lateral pressuring until the width(s) of Veneer(s) A is equal to the width of the mold frame; then fixed thickness strongly pressing by a hot presser is performed to reduce the thickness(es) of Veneer(s) A to that of the frame mold with fixed thickness.

8. The manufacturing method of reconstituted wood panel with natural wood grain according to claim 2, wherein, in step c, the said adhesive is the water soluble phenolic resin, or the mixed liquid of water soluble phenolic resin glue and nitrile rubber emulsion, and the solids content is 2045%; the pressure impregnating method is used, and the impregnating pressure is controlled to 0.31.0 MPa; there is a secondary drying step between step c and d, specifically: drying the impregnated Veneer A at the temperature of 6090 C. to a moisture content of 612%; in step d, when performing hot pressing, the temperature of the press plate surface is controlled to 125140 C. and the vertical pressure acting on the panel is at least 15 kg/cm.sup.2.

9. The manufacturing method of reconstituted wood panel with natural wood grain according to claim 2, wherein, in step c, the said adhesive is water soluble urea-formaldehyde resin; there is a secondary drying step between step c and d, specifically: drying the impregnated Veneer A at a low temperature below 50 C. to a moisture content of 20% or less; in step d, the secondary dried Veneer A is promptly sent to a presser for splits repairing and curing at the temperature of 90115 C.

10. The manufacturing method of reconstituted wood panel with natural wood grain according to claim 2, wherein, in step c, the said adhesive is polyurethane; pre-treatment of said Veneer A is conducted before impregnating polyurethane, and the said pre-treatment comprises the following steps: (1) immersing said Veneer A in alkaline water; (2) rinsing after cooking, and dredging the pores of said Veneer A by a vacuum suction method; (3) drying said Veneer A to a moisture content of 10% or less; (4) pressing the polyurethane adhesive into said Veneer A by the pressure impregnating method; and (5) curing at room temperature after pressing said Veneer A by the method of constant mold width and the method of constant mold thickness, and taking out the panel.

11. The manufacturing method of reconstituted wood panel with natural wood grain according to claim 2, wherein, in step b, a continuous conveying dryer is used for rapid drying at the drying temperature of 75120 C. and the drying time of 60300 min, in order to control the moisture content of Veneer A to 715%.

12. The manufacturing method of reconstituted wood panel with natural wood grain according to claim 2, wherein, in the said mixed liquid of water soluble phenolic resin and nitrile rubber emulsion, the nitrile rubber emulsion accounts for 515% by weight of water soluble phenolic resin in which the solids content is 45%.

13. The manufacturing method of reconstituted wood panel with natural wood grain according to claim 2, wherein, in step d, the method of constant mold width is used when repairing the longitudinal splits and the longitudinal portion of the oblique splits; the method of constant mold thickness is employed when repairing the transverse splits and the transverse portion of the oblique splits.

14. The manufacturing method of reconstituted wood panel with natural wood grain according to claim 2, wherein, in step d, placing one or more Veneer(s) A in the mold frame, a presser is used to compress one or more Veneer(s) A by two-sides or one-side lateral pressuring until the width(s) of Veneer(s) A is equal to the width of the mold frame; then fixed thickness strongly pressing by a hot presser is performed to reduce the thickness(es) of Veneer(s) A to that of the frame mold with fixed thickness.

15. The manufacturing method of reconstituted wood panel with natural wood grain according to claim 3, wherein, in step c, the said adhesive is the water soluble phenolic resin, or the mixed liquid of water soluble phenolic resin glue and nitrile rubber emulsion, and the solids content is 2045%; the pressure impregnating method is used, and the impregnating pressure is controlled to 0.31.0 MPa; there is a secondary drying step between step c and d, specifically: drying the impregnated Veneer A at the temperature of 6090 C. to a moisture content of 612%; in step d, when performing hot pressing, the temperature of the press plate surface is controlled to 125140 C. and the vertical pressure acting on the panel is at least 15 kg/cm.sup.2.

16. The manufacturing method of reconstituted wood panel with natural wood grain according to claim 3, wherein, in step c, the said adhesive is water soluble urea-formaldehyde resin; there is a secondary drying step between step c and d, specifically: drying the impregnated Veneer A at a low temperature below 50 C. to a moisture content of 20% or less; in step d, the secondary dried Veneer A is promptly sent to a presser for splits repairing and curing at the temperature of 90115 C.

17. The manufacturing method of reconstituted wood panel with natural wood grain according to claim 3, wherein, in step c, the said adhesive is polyurethane; pre-treatment of said Veneer A is conducted before impregnating polyurethane, and the said pre-treatment comprises the following steps: (1) immersing said Veneer A in alkaline water; (2) rinsing after cooking, and dredging the pores of said Veneer A by a vacuum suction method; (3) drying said Veneer A to a moisture content of 10% or less; (4) pressing the polyurethane adhesive into said Veneer A by the pressure impregnating method; and (5) curing at room temperature after pressing said Veneer A by the method of constant mold width and the method of constant mold thickness, and taking out the panel.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Sole FIGURE is the schematic view showing the panel splits of Veneer A in the present invention.

[0045] In the Sole FIGURE, 1longitudinal split, 2transverse split, and 3oblique split.

PREFERRED EMBODIMENTS CARRYING OUT THE PRESENT INVENTION

Preferred Embodiments of the Present Invention

[0046] The reconstituted wood panel with natural wood grain is manufactured by the following method: [0047] a. cutting the oak logs from northeast China into lumber sections with length of 2000 mm, and cooking to soften the wood, and then oak veneers with length of 2000 mm, width of 140 mm and thickness of 16 mm being obtained by a peeling process; [0048] b. placing the veneers into a dryer at 75 C. to control the moisture content of 11%, and taking them out; wherein at this time, the lengths of the veneers are basically maintained at 2000 mm, while the widths have different shrinkages, ranging from 134 mm to 136 mm, and the thicknesses vary from 15.2 mm to 15.4 mm; [0049] c. putting the veneers into a container pre-filled with compatibility of water and other two solutions, respectively 30% solids content water-soluable phenolic resin and 45% solids content nitrile rubber emulsion, wherein the content of nitrile rubber emulsion is 7% of that of water-soluable phenolic resin; closing the door of the container, feeding into compressed air, and holding the pressure for 120 minutes when the pressure gauge shows 0.6 MPa; then expelling the exhaust and opening the door to take out the veneers. [0050] d. checking the veneers to see that the mixed liquid has been permeated, and filtering the excess liquid; [0051] e. sending the veneers to a drying kiln at 70 C. to dry until the moisture content is 10%, then taking them out, and at this time, checking the size of veneers to see that there are no significant changes of the lengths, being 2000 mm, and the widths have an error, about 132-136 mm, and the thicknesses also have an error, about 15.0-15.3 mm;

[0052] f. placing the veneers into a hot presser with a mold of fixed thickness of 13.4 mm, and width of 130 mm; wherein, the hot presser is a 4-layer one, and each layer is placed with 4 veneers, namely a total of 16 veneers; [0053] g. adjusting the temperature of the press plate surface to 133-135 C.; [0054] h. after the veneers are placed into the mold, firstly, closing the hot press steel plate to adhere to the veneers, then setting the width of the mold to 130 mm for side pressuring, and then hot pressing vertically up and down to the thickness of the veneers being 14 mm; taking out the veneers after curing for 18 minutes at the above pressure and temperature; wherein, the longitudinal splits 1, transverse splits 2 and oblique splits 3 as shown in Sole FIGURE are all repaired during the process; and [0055] i. sanding the veneers to obtain finished oak hard veneers, which have lengths of 2000 mm, uniform widths of 130 mm and thicknesses of 13 mm.

EMBODIMENTS OF THE INVENTION

Embodiment 1

[0056] The reconstituted wood panel with natural wood grain is manufactured by the following method: [0057] a. cutting the oak logs from northeast China into lumber sections with length of 2000 mm, and cooking to soften the wood, and then oak veneers with length of 2000 mm, width of 250 mm and thickness of 6.16.5 mm being obtained by a peeling process; [0058] b. placing the veneers in a dryer at 75 C. to control the moisture content of 1011%, and taking them out; wherein at this time, the lengths of the veneers are basically maintained at 2000 mm, while the widths have different shrinkages, ranging from 238 mm to 242 mm, and the thicknesses vary from 5.8 mm to 6.2 mm; [0059] c. putting the veneers into a pressure vessel pre-filled with compatibility of 25% solids content water soluble phenolic resin adhesive, and closing the vessel door; [0060] d. feeding into compressed air, and when the pressure gauge shows 0.4 MPa, holding for 60 minutes; then expelling the exhaust and opening the door to take out the veneers and placing for 1.5 hours to filter out the excess liquid in the surface of veneers; [0061] e. sending the veneers to the 75 C. dryer to dry until the moisture content is 10% then taking them out, and at this time, checking the size of veneers to see that there are no significant changes of the length, being 2000 mm, and the widths have an error, about 237-240 mm, and the thicknesses also have an error, about 5.6-6.0 mm; [0062] f. placing the veneers into a hot presser with a mold of fixed thickness of 5.0 mm, and width of 235 mm; wherein, the hot presser is a 4-layer one, and each layer is placed with 4 veneers, namely a total of 16 veneers; [0063] g. adjusting the temperature of the press plate surface to 134-137 C.; [0064] h. after the veneers are placed into the mold, firstly, closing the hot press steel plate to adhere to the veneers, then setting the width of the mold to 235 mm for side pressuring, and then hot pressing vertically up and down to the thickness of the veneers being 5.0 mm; taking out the veneers after curing for 12 minutes at the above pressure and temperature; wherein, the longitudinal splits 1, transverse splits 2 and oblique splits 3 as shown in Sole FIGURE are all repaired during the process; and [0065] i. sanding the veneers to obtain finished oak hard veneers, which have lengths of 2000 mm, uniform widths of 235 mm and thicknesses of 4.6 mm.

Embodiment 2

[0066] The reconstituted wood panel with natural wood grain is manufactured by the following method: [0067] a. cutting the eucalyptus logs from Guangxi Province, China into lumber sections with length of 2000 mm, and cooking to soften the wood, and then eucalyptus veneers with length of 2000 mm, width of 600 mm and thickness of 6.2 mm being obtained by a peeling process; [0068] b. placing the veneers in a dryer at 75 C. to control the moisture content of 10%, and taking them out; wherein at this time, the lengths of the veneers are basically maintained at 2000 mm, while the widths have different shrinkages, ranging from 553 mm to 580 mm, and the thicknesses vary from 5.7 mm to 6.0 mm; [0069] c. putting the veneers into a pressure vessel pre-filled with compatibility of 40% solids content water soluble urea-formaldehyde resin adhesive, and closing the vessel door; [0070] d. feeding into compressed air, and when the pressure gauge shows 0.6 MPa, holding for 60 minutes; then expelling the exhaust and opening the door to take out the veneers and placing for 1.0 hours to filter out the excess liquid in the surface of veneers; [0071] e. sending the veneers to the 45 C. dryer to dry until the moisture content is 17% then taking them out, and at this time, checking the size of veneers to see that there are no significant changes of the length, being 2000 mm, and the widths have an error for the logs from different parts have different original densities, about 553-575 mm, and the thicknesses also have an error, about 5.6-5.8 mm; [0072] f. placing the veneers into a hot presser with a mold of fixed thickness of 5.0 mm, and width of 550 mm; wherein, the hot presser is a 4-layer one, and each layer is placed with 2 veneers, namely a total of 8 veneers; [0073] g. adjusting the temperature of the press plate surface to 96-100 C.; [0074] h. after the veneers are placed into the mold, firstly, closing the hot press steel plate to adhere to the veneers, then setting the width of the mold to 550 mm for side pressing, and then hot pressing vertically up and down to the thickness of the veneers being 5.0 mm; taking out the veneers after kept for 10 minutes at the above pressure and temperature; wherein, the longitudinal splits 1, transverse splits 2 and oblique splits 3 as shown in Sole FIGURE are all repaired during the process; and [0075] i. sanding the veneers to obtain finished eucalyptus hard veneers, which have lengths of 2000 mm, uniform widths of 550 mm and thicknesses of 4.6 mm.

Embodiment 3

[0076] The reconstituted wood panel with natural wood grain is manufactured by the following method: [0077] a. cutting poplar logs from Shandong Province into lumber sections with length of 1000 mm, and cooking to soften the wood, and then poplar veneers with length of 1000 mm, width of 600 mm and thickness of 6.2 mm being obtained by a peeling process; [0078] b. immersing the veneers in alkaline aqueous solution for 3 hours at 80 C., and cooking in 90-95 C. water for 2 hours, then sending to a sealed tank for evacuation to dredge the fiber pores of wood, which is good for impregnating; then placing the veneers to 75 C. dryer to control the moisture content of 6%, and taking them out; wherein at this time, the lengths of veneers are 1000 mm without significant changes, while the widths have different shrinkages, ranging from 550 mm to 550 mm, and the thicknesses vary from 5.5 mm to 5.7 mm; [0079] c. putting the veneers into a pressure vessel, and injecting the polyurethane liquid immediately, then closing the vessel door; [0080] d. propelling the polyurethane liquid in the tank using a screw piston with the principle of medical hand push syringe to make the adhesive completely flood the veneers, and closing the top valve after expelling the exhaust; the screw continuing to advance the piston until the pressure gauge shows 1.0 MPa, and keeping the pressure for 60 minutes; then retreating the threaded top rod and opening the top valve to let the air in, and then opening the door at normal pressure, and taking out the veneers to filter out the excess liquid; [0081] e. placing the veneers into a ten-layer presser coated with release agent, with a mold of fixed thickness of 5.3 mm, and width of 525 mm; wherein, each layer is placed with 2 veneers, namely a total of 20 veneers; [0082] f. after the veneers are placed into the mold, firstly, closing the hot press steel plate to adhere to the veneers, then setting the width of the mold to 525 mm for side pressing, and then hot pressing vertically up and down to the thickness of the veneers being 5.3 mm; decompressing and taking out the veneers after kept for 12 hours at the above pressure after completely curing at room temperature; wherein, the longitudinal splits 1, transverse splits 2 and oblique splits 3 as shown in Sole FIGURE are all repaired during the process; and [0083] g. sanding the veneers to obtain finished poplar hard veneers, which have lengths of 1000 mm, uniform widths of 525 mm and thicknesses of 5.0 mm.

[0084] As can be seen from Embodiment 3, the major difference between using polyurethane resin in Embodiment 3 and water soluble phenolic resin and urea-formaldehyde resin is that the presser does not need to be heated, and the volume loss of the final product is reduced, so the available material volume is increased. Injecting the polyurethane into the interior of the wood has a good filling effect, and it increases the density of the wood. Although the compression ratio is not 10%, but the degree of compactness of the wood is increased and the mechanical properties are also improved.

Embodiment 4

[0085] The reconstituted wood panel with natural wood grain is manufactured by the following method: [0086] a. cutting the oak logs from northeast China into lumber sections with length of 2000 mm, and cooking to soften the wood, and then oak veneers with length of 2000 mm, width of 140 mm and thickness of 16 mm being obtained by a peeling process; [0087] b. placing the veneers in a dryer at 75 C. to control the moisture content of 11%, and taking them out; wherein at this time, the lengths of the veneers are basically maintained at 2000 mm, while the widths have different shrinkages, ranging from 134 mm to 136 mm, and the thicknesses vary from 15.2 mm to 15.4 mm; [0088] c. putting the veneers into a container pre-filled with compatibility of water and other two solutions, respectively 30% solids content water-soluble phenolic resin and 45% solids content nitrile rubber emulsion, wherein the content of nitrile rubber emulsion is 7% of that of water-soluble phenolic resin; closing the door of the container, and feeding into compressed air, and holding the pressure for 120 minutes when the pressure gauge shows 0.6 MPa; then expelling the exhaust and opening the door to take out the veneers. [0089] d. checking the veneers to see that the mixed liquid has been permeated, and taking out the veneers and filtering the excess liquid; [0090] e. sending the veneers to a drying kiln at 70 C. to dry until the moisture content is 10% then taking them out, and at this time, checking the size of veneers to see that there are no significant changes of the lengths, being 2000 mm, and the widths have an error for the logs from different parts have different original densities, about 132-136 mm, and the thicknesses also have an error, about 15.0-15.3 mm; [0091] f. placing the veneers into a hot presser with a mold of fixed thickness of 13.4 mm, and width of 130 mm; wherein, the hot presser is a 4-layer one, and each layer is placed with 4 veneers, namely a total of 16 veneers; [0092] g. adjusting the temperature of the press plate surface to 133-135 C.; [0093] h. after the veneers are placed into the mold, firstly, closing the hot press steel plate to adhere to the veneers, then setting the width of the mold to 130 mm for side pressing, and then hot pressing vertically up and down to the thickness of the veneers being 14 mm; taking out the veneers after curing for 18 minutes at the above pressure and temperature; wherein, the longitudinal splits 1, transverse splits 2 and oblique splits 3 as shown in Sole FIGURE are all repaired during the process; and [0094] i. sanding the veneers to obtain finished oak hard veneers, which have lengths of 2000 mm, uniform widths of 130 mm and thicknesses of 13 mm.

[0095] Panels with uniform thickness and width are produced using the reconstituted wood panel with natural wood grain manufactured in the invention and the sawn wood board of the same tree species, and processed to a moisture content of 910%, then tested according to the standard GB/T 17657-2013 Test methods of evaluating the properties of wood-based panels and surface decorated wood-based panels and LY/T 1984-2011 Reconstituted wood flooring. The results are shown in the following table:

TABLE-US-00001 [Number] Comparison of test results of physical properties Test items and method Thickness swelling rate Internal (%) bonding Immersing in Thermal cycling strength Density water at 20 C. Method 2 of GB/T (MPa) (g/cm.sup.3) Specimen information for 24 hours 17657-2013, 5 times / / Oak log, Embodiment 1 3.8 No splits and no blister 5.1 0.92 Heilongjiang on the surface. Province Sawn wood 6.2 No splits and no blister 3.6 0.72 board on the surface. Eucalyptus Embodiment 2 4.2 Slight splits and no 3.8 0.80 log, Guangxi bister on the surface. Province Sawn wood 5.1 Slight splits and no 2.8 0.60 board bister on the surface. Poplar log, Embodiment 3 0.2 No splits and no blister 7.6 0.60 Shandong on the surface. Province Sawn wood 4.9 No splits and no blister 2.2 0.45 board on the surface. Oak log, Embodiment 4 2.9 No splits and no blister 6.3 1.04 Heilongjiang on the surface. Province Sawn wood 5.2 No splits and no blister 3.6 0.72 board on the surface.

[0096] It can be found that, by comparing the reconstituted wood panels with natural wood grain and the sawn wood boards of the same tree species, the physical and mechanical properties have different degrees of improvement. The products can be processed into floor, furniture and others with increased density, enhanced resistance to deformation and splits and reduced production costs. The manufacturing method in the present invention fully utilizes fast-growing wood and it saves energy. Besides, it is environmentally friendly. The products have a wide range of applications. There is a great significance to spread the manufacturing method.