A method for improving the impregnation peeling performance between the wood particle layer and the veneer layer of wood particle veneered plywood

Abstract

The present invention discloses a method for improving the impregnation peeling performance between the wood particle layer and the veneer layer of a wood particle veneered plywood, belonging to the technical field of plywood preparation. The present invention uses plywood as the base material and wood particles as the facing material, and wood particle layers are provided on the upper and lower surfaces of the plywood. Under the action of pressure, the wood particles can be embedded into the veneer to form a staggered bonding, thereby improving the bonding strength between the two. At the same time, glue is evenly applied to the upper and lower surfaces of the prepared plywood, and then the wood particles are laid on the upper and lower surfaces of the plywood, which is equivalent to coating a layer of glue on the surface of the wood particles on the plywood surface. After being embedded into the surface veneer, the firmness is better, further improving the bonding strength.

Description

Technical Field

[0001] The present invention relates to the technical field of plywood preparation, and particularly to a method for improving the impregnation peeling performance between the wood particle layer and the veneer layer of wood particle veneered plywood. Background Art

[0002] Plywood is a traditional wood-based panel recombined with rotary-cut veneers as the basic unit. It has advantages such as a good solid wood feel, excellent physical and mechanical properties, and good processing performance, and is accepted by the majority of consumers. Currently, it has become the mainstream variety of wood-based panels in China. At present, most plywood needs to be surface-finished before being used in the manufacture and application of household products. The impregnated paper veneered plywood (commonly known as ecological board), due to its beautiful, generous appearance, harmonious color tone, and characteristics such as heat resistance, wear resistance, and waterproofness, is widely used in household manufacturing such as furniture, floors, cabinets, doors and windows, as well as decorative and finishing materials.

[0003] When using fast-growing forest wood for plywood, there are problems such as soft substrate material, many defects, and rough surface, and it cannot be directly veneered with melamine impregnated paper or precious tree species thin veneer. The current process is to first perform putty treatment on the surface, and then use rotary-cut (planed) thin veneer or thin fiberboard to press and paste on its surface to improve its surface quality to meet the needs of veneering. Rotary-cut (planed) thin veneer requires no knots, decay and other defects. However, with the reduction of high-quality wood resources, high-quality rotary-cut (planed) thin veneer is difficult to meet the production demand. Therefore, people try to compound a 1.0 - 3.0 mm fiberboard on the upper and lower surfaces of plywood. However, due to the small bonding interface between the fiberboard and the plywood, the impregnation peeling performance is poor, and there is usually a phenomenon of delamination during use, as Figure 1 shown. Summary of the Invention

[0004] To solve the above technical problems, the present invention provides a method for improving the impregnation peeling performance between the wood particle layer and the veneer layer of wood particle veneered plywood. In the present invention, wood particle layers are pressed on the upper and lower surfaces of the plywood. Under the action of pressure, the wood particles can be embedded into the veneer to form a staggered bond, improving the bonding strength between the two. At the same time, glue is evenly applied to the upper and lower surfaces of the prepared plywood, and then the wood particles are laid on the upper and lower surfaces of the plywood, which is equivalent to coating a layer of glue on the surface of the wood particles. After being embedded into the plywood, the firmness is better, further improving the bonding strength.

[0005] To solve the above technical problems, the present invention provides the following technical solutions:

[0006] On the one hand, the present invention provides a method for improving the impregnation peeling performance between the wood particle layer and the veneer layer of wood particle veneered plywood, including:

[0007] (1) Preparation of plywood

[0008] Prepare logs into veneers, and then obtain plywood with a moisture content of 6-12% through sizing, layup, hot pressing, and thicknessing.

[0009] (II) Sizing of plywood

[0010] Adopt the roller coating method to evenly coat phenolic resin, urea formaldehyde or melamine urea formaldehyde resin adhesives on the upper and lower surfaces of the plywood. The sizing amount is 150-200 g / m 2 ; The adhesive used has a resin solid content of 58-65%, and the flour addition amount of the resin is 30-40% of the weight of the glue solution;

[0011] (III) Preparation of wood particles

[0012] The waste veneers during rounding and the remaining waste veneers during cutting are processed through crushing and screening to obtain wood particles with the following particle size distribution in the table, and are dried by a roller dryer to a moisture content of 1-3%;

[0013]

[0014] (IV) Sizing of wood particles

[0015] Spray isocyanate evenly on the surface of the wood particles. The spray pressure is 2.5-3.2 MPa, the sizing amount is 3-6% of the weight of the wood particles, and the tackifier addition amount is 0.7%-1% of the weight of the wood particles; the rotation speed of the glue mixer is 450-550 r / min, and the tackifier is polyethylene glycol;

[0016] (V) Humidity adjustment of wood particles

[0017] Spray a certain amount of water evenly on the surface of the wood particles. The water addition amount is 8-15% of the weight of the wood particles;

[0018] (VI) Layup of wood particles

[0019] Divide the sized wood particles into two equal parts and enter the layup machine respectively. First, use the air layup method to lay the bottom wood particles in the bottom plate conveyor belt with a layup thickness of 1.5-2.0 cm, and then use the robotic arm to place the plywood above the bottom wood particles. Finally, lay the other half of the wood particles on the upper surface of the multi-layer board using the air layup method with a layup thickness of 1.5-2.0 cm. The belt feeding speed is 17-18 m / min, which will be adjusted according to the output and weather. Use online pre-pressing to pre-press the board blank with a pressure of 2-5 MPa; the total thickness of the pre-pressed board is 2.7-2.8 cm;

[0020] (VII) Hot pressing

[0021] The hot pressing process is the most important link in the development of new products and the basis for the continuous operation of the production line. The hot pressing temperature, pressure, and heat transfer oil speed will directly affect the performance of the products. The above pre-pressed plates are hot pressed for 75 s at a hot pressing temperature of 180 - 230 °C, and the pressure is gradually reduced from 480 - 520 bar to 80 - 100 bar, and then cooled naturally.

[0022] Preferably, the wood particles are obtained by sawing or planing and have a spindle-shaped structure with pointed ends or a cuboid structure.

[0023] Preferably, in step (7), the hot pressing process is specifically as follows: 220 - 230 °C, 480 - 520 bar, 10 - 40 s; 210 °C, 330 - 240 bar, 15 - 40 s; 190 °C, 200 - 100 bar, 15 - 40 s; 180 °C, 100 - 80 bar, 15 - 60 s.

[0024] Furthermore, plywood can be prepared by the following method:

[0025] Veneer preparation: The log is sawn into wood segments with a length of 1240 - 1350 mm or 2440 - 270 mm. After debarking the wood segments, they are rounded, and the wood segments are rotary cut into veneers with a thickness of 1 - 2 mm by a rotary cutting machine, and then cut into veneers with a size of 600 - 750 mm or 1200 - 1300 mm. Then, the veneers are naturally dried or dried by a mesh belt dryer to control the moisture content between 6 - 12%.

[0026] Veneer sizing: The veneer is sized by a roller coating method, and phenol formaldehyde, urea formaldehyde melamine, or urea formaldehyde resin is evenly coated on the surface of the veneer. The sizing amount is 200 - 250 g / m 2 , with a solid content of 62%, and the flour addition amount of the adhesive is 30 - 40% of the flour;

[0027] Veneer layup

[0028] Five, seven, nine, eleven, thirteen, or fifteen layers of the veneers are laid up in a parallel and / or cross structure; then, the board blank is pre-pressed by cold pressing, with a pre-pressing pressure of 0.8 - 1.3 MPa, a pre-pressing time of 2 - 8 h, and a pre-pressing temperature of 5 - 35 °C;

[0029] Plywood hot pressing

[0030] The above board blank is sent into a hot press for hot pressing, with a hot pressing temperature of 110 - 135 °C, a hot pressing time of 0.8 - 1.5 min / mm, and a hot pressing pressure of 0.8 - 1.5 MPa;

[0031] Plywood thickness sizing

[0032] After cooling the above slab, a sander is used to sand the hot-pressed slab, and the thickness deviation of the sanded slab is controlled within ±0.3 mm.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] On the one hand, the present invention presses a layer of wood particles on the upper and lower surfaces of the plywood. The wood particles are similar to nails and can be embedded into the veneer under pressure to form a staggered bonding, improving the bonding strength between the two. On the other hand, by evenly applying glue on the upper and lower surfaces of the prepared plywood and then laying the wood particles on the upper and lower surfaces of the plywood, it is equivalent to impregnating the wood particles in contact with the plywood into the adhesive, coating a layer of glue on the surface of the wood particles. After being embedded in the plywood, the firmness is better, further improving the bonding strength. On the other hand, the wood particles are in a spindle or cuboid shape, which is more convenient for them to be embedded into the plywood under pressure, increasing the bonding strength and preventing delamination. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a picture of the board with fiberboard pasted on the surface of plywood in the prior art after impregnation;

[0036] Figure 2 It is a picture of the wood particle veneered plywood prepared in Example 1 after impregnation;

[0037] Figure 3 It is a picture of the wood particle veneered plywood prepared in Comparative Example 1 after impregnation. DETAILED DESCRIPTION OF THE INVENTION

[0038] To make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will be described in detail with reference to specific drawings and embodiments.

[0039] In the present invention, materials and reagents used without special description can be obtained from commercial channels.

[0040] On the one hand, the present invention provides a method for improving the impregnation and peeling performance between the wood particle layer and the veneer layer of wood particle veneered plywood, including:

[0041] (I) Preparation of plywood

[0042] The log is made into veneer, and then through sizing, assembling, hot pressing and thickness fixing, plywood with a water content of 6-12% is obtained;

[0043] The plywood can be prepared by methods in the prior art, for example:

[0044] Single-board preparation: Saw the log into wood segments with a length of 1240 - 1350 mm or 2440 - 270 mm. After peeling the wood segments, round them up, and use a veneer lathe to cut the wood segments into veneers with a thickness of 1 - 2 mm. Cut the veneers into veneers with a size of 600 - 750 mm or 1200 - 1300 mm. Then, naturally dry or dry the veneers on a mesh belt dryer to control the moisture content between 6 - 12%;

[0045] Veneer sizing: The veneer is sized by the roller coating method, and phenolic resin, urea - formaldehyde melamine, or urea - formaldehyde resin is evenly coated on the surface of the veneer. The sizing amount is 200 - 250 g / m 2 , with a solid content of 62%. The flour addition amount of the adhesive is 30 - 40% of the flour;

[0046] Veneer lay - up

[0047] Lay up 5, 7, 9, 11, 13, or 15 layers of the veneers in a parallel and / or cross - structure. Then, pre - press the board blank by cold pressing. The pre - pressing pressure is 0.8 - 1.3 MPa, the pre - pressing time is 2 - 8 h, and the pre - pressing temperature is 5 - 35 °C;

[0048] Plywood hot - pressing

[0049] Feed the above - mentioned board blank into a hot - press for hot - pressing. The hot - pressing temperature is 110 - 135 °C, the hot - pressing time is 0.8 - 1.5 min / mm, and the hot - pressing pressure is 0.8 - 1.5 MPa;

[0050] Plywood thickness - sizing

[0051] After cooling the above - mentioned board blank, sand the hot - pressed board blank with a sander. The thickness deviation of the sanded board blank is controlled within ±0.3 mm. (II) Plywood sizing

[0052] Adopt the roller coating method to evenly coat the adhesive phenolic resin, urea - formaldehyde, or melamine - urea - formaldehyde resin on the upper and lower surfaces of the plywood. The sizing amount is 150 - 200 g / m 2 ; The used adhesive has a resin solid content of 58 - 65%, and the flour addition amount of the resin is 30 - 40% of the weight of the glue solution;

[0053] (III) Wood particle preparation

[0054] The waste veneers during rounding and the remaining waste veneers during cutting are crushed and then screened and processed to obtain wood particles with the following particle size distribution in the table, and are dried by a roller dryer to a moisture content of 1 - 3%;

[0055]

[0056] (IV) Wood particle sizing

[0057] The isocyanate is evenly sprayed onto the surface of the wood particles. The spraying pressure is 2.5 - 3.2 MPa, the sizing amount is 3 - 6% of the weight of the wood particles, and the tackifier addition amount is 0.7% - 1% of the weight of the wood particles. The rotation speed of the glue mixer is 450 - 550 r / min;

[0058] (V) Humidity adjustment of wood particles

[0059] A certain amount of water is evenly sprayed onto the surface of the wood particles. The addition amount of water is 8 - 15% of the weight of the wood particles;

[0060] (VI) Laying of wood particles

[0061] The sized wood particles are evenly divided into two parts and enter the placer respectively. Using the air - laying method, first lay the bottom - layer wood particles in the bottom - plate conveyor belt, with a laying thickness of 1.5 - 2.0 cm. Then, use a robotic arm to place the plywood above the bottom - layer wood particles. Finally, lay the other half of the wood particles on the upper surface of the plywood using the air - laying method, with a laying thickness of 1.5 - 2.0 cm. The belt feeding speed is 17 - 18 m / min, which will be adjusted according to the output and weather. Online pre - pressing is used to pre - press the slab, with a pressure of 5 MPa; the total thickness of the pre - pressed board is 2.7 - 2.8 cm;

[0062] (VII) Hot pressing

[0063] The hot - pressing process is the most important link in the development of new products and is the basis for the continuous operation of the production line. The hot - pressing temperature, pressure, and heat - conducting oil speed will directly affect the performance of the product. The above - mentioned pre - pressed board is hot - pressed. The hot - pressing time is 75 s, the hot - pressing temperature is 180 - 230 °C, the pressure is gradually reduced from 480 - 520 bar to 80 - 100 bar, and then it is naturally cooled.

[0064] Preferably, the wood particles are obtained by sawing or planing and have a spindle - shaped structure with pointed ends or a cuboid structure.

[0065] Preferably, in the step (VII), the hot - pressing process is specifically as follows: 220 - 230 °C, 480 - 520 bar, 10 - 40 s; 210 °C, 330 - 240 bar, 15 - 40 s; 190 °C, 200 - 100 bar, 15 - 40 s; 180 °C, 100 - 80 bar, 15 - 60 s.

[0066] Specific embodiments are as follows.

[0067] Example 1

[0068] A method for improving the impregnation and peeling performance between the wood - particle layer and the veneer layer of wood - particle - faced plywood, including:

[0069] (1) Preparation of plywood

[0070] The eucalyptus wood is made into veneer, and then through sizing, assembling, hot pressing and thickness fixing, plywood with a water content of 6% is obtained. Specifically:

[0071] Veneer preparation: The eucalyptus wood is sawn into wood segments 1240 mm long. After the wood segments are peeled, they are rounded, and the wood segments are rotary cut into veneer with a thickness of 1.5 mm by a rotary cutting machine, and then cut into veneer of 600. After that, the veneer is naturally dried and dried by a mesh belt dryer, and the moisture content is controlled at 8%;

[0072] Veneer sizing: The veneer adopts the roller coating method, and phenolic resin is evenly coated on the surface of the veneer, and the sizing amount is 220 g / m 2 , the solid content of phenolic resin is 62%, and the addition amount of flour in the adhesive is 30% of flour;

[0073] Veneer assembling: Seven layers of the veneer are assembled in a parallel and / or cross structure; then, the board blank is pre-pressed by cold pressing, the pre-pressing pressure is 1 MPa, the pre-pressing time is 4 h, and the pre-pressing temperature is 35 °C;

[0074] Plywood hot pressing: The above board blank is sent into a hot press for hot pressing, the hot pressing temperature is 120 °C, the hot pressing time is 0.8 min / mm, and the hot pressing pressure is 1 MPa;

[0075] Plywood thickness fixing: After the above board blank is cooled, the hot-pressed board blank is sanded by a sander, and the thickness deviation of the sanded board blank is controlled within ±0.3 mm.

[0076] (2) Plywood sizing

[0077] Adopt the roller coating method to evenly coat the phenolic resin adhesive on the upper and lower surfaces of the plywood, and the sizing amount is 150 g / m 2 ; the adhesive used has a resin solid content of 62%, and the flour addition amount of the resin is 35% of the weight of the glue solution;

[0078] (3) Preparation of wood particles

[0079] The waste veneer during rounding and the remaining waste veneer during cutting are crushed and screened to obtain wood particles with the following particle size distribution. The wood particles are obtained by sawing, are spindle-shaped knots with pointed ends at both ends, and are dried by a roller dryer to obtain wood particles with a moisture content of 1%;

[0080]

[0081] (4) Wood particle sizing

[0082] The isocyanate is evenly sprayed onto the surface of the wood particles. The spraying pressure is 2.5 MPa, the sizing amount is 3% of the weight of the wood particles, and the tackifier addition amount is 0.7% of the weight of the wood particles; the rotation speed of the glue mixer is 450 r / min;

[0083] (V) Humidity adjustment of wood particles

[0084] A certain amount of water is evenly sprayed onto the surface of the wood particles. The water addition amount is 8% of the weight of the wood particles;

[0085] (VI) Laying of wood particles

[0086] The sized wood particles are evenly divided into two parts and enter the layer former respectively. The pneumatic laying method is used to lay the bottom layer of wood particles in the bottom plate conveyor belt first, with a laying thickness of 1.5 cm. Then, the plywood is placed above the bottom layer of wood particles by a robotic arm. Finally, the other half of the wood particles are also laid on the upper surface of the plywood by the pneumatic laying method, with a laying thickness of 1.5 cm. The belt feeding speed is 17 m / min. The slab is pre-pressed by online pre-pressing, with a pressure of 5 MPa; the total thickness of the pre-pressed board is 2.7 cm;

[0087] (VII) Hot pressing

[0088] The above pre-pressed board is hot-pressed. The hot-pressing time is 100 s. The specific hot-pressing process is as follows: 230 °C, 480 bar, 20 s; 210 °C, 300 bar, 20 s; 190 °C, 150 bar, 30 s; 180 °C, 80 bar, 30 s, and then it is naturally cooled.

[0089] Example 2

[0090] A method for improving the impregnation peeling performance between the wood particle layer and the veneer layer of the wood particle faced plywood, including:

[0091] (I) The plywood preparation method is the same as that in Example 1;

[0092] The poplar wood is made into veneers, and then through sizing, assembling, hot pressing, and thicknessing, plywood with a water content of 8% is obtained; specifically:

[0093] Other plywood manufacturing methods are the same as those in Example 1;

[0094] (II) Plywood sizing

[0095] The roller coating method is adopted to evenly coat the adhesive phenolic resin on the upper and lower surfaces of the plywood. The sizing amount is 150 g / m 2 ; the adhesive used has a resin solid content of 62%, and the flour addition amount of the resin is 35% of the weight of the glue solution;

[0096] (3) Preparation of Wood Particles

[0097] The waste veneers during rounding and the remaining waste veneers during cutting are crushed and then screened and processed to obtain wood particles with the following particle size distribution. The wood particles are obtained by sawing, with a spindle-shaped knot that is pointed at both ends, and are dried using a roller dryer to obtain wood particles with a moisture content of 3%.

[0098]

[0099] (4) Gluing of Wood Particles

[0100] Isocyanate is evenly sprayed onto the surface of the wood particles. The spraying pressure is 3.2 MPa, the gluing amount is 6% of the weight of the wood particles, and the addition amount of the tackifier polyethylene glycol is 1% of the weight of the wood particles. The rotation speed of the glue mixer is 550 r / min.

[0101] (5) Humidity Adjustment of Wood Particles

[0102] A certain amount of water is evenly sprayed onto the surface of the wood particles. The addition amount of water is 15% of the weight of the wood particles.

[0103] (6) Laying of Wood Particles

[0104] The glued wood particles are evenly divided into two parts, which respectively enter the layer forming machine. The air-laying method is used to first lay the bottom layer of wood particles on the bottom board conveyor belt, with a laying thickness of 2.0 cm. Then, a plywood board is placed above the bottom layer of wood particles using a robotic arm. Finally, the other half of the wood particles are also laid on the upper surface of the multi-layer board using the air-laying method, with a laying thickness of 2.0 cm. The belt feeding speed is 18 m / min. Online pre-pressing is used to pre-press the board blank, with a pressure of 5 MPa; the total thickness of the pre-pressed board is 2.8 cm.

[0105] (7) Hot Pressing

[0106] The above pre-pressed board is hot-pressed. The hot-pressing time is 75 s. The specific hot-pressing process is as follows: 220 °C, 520 bar, 10 s; 210 °C, 330 bar, 15 s; 190 °C, 200 bar, 20 s; 180 °C, 100 bar, 30 s.

[0107] Example 3

[0108] A method for improving the impregnation and peeling performance between the wood particle layer and the veneer layer of a wood particle veneered plywood, including:

[0109] (1) The plywood preparation method is the same as that in Example 2;

[0110] (2) The plywood gluing method is the same as that in Example 1;

[0111] (III) Preparation of Wood Particles

[0112] The waste veneers during rounding and the remaining waste veneers during cutting are crushed and then screened and processed to obtain wood particles with the following particle size distribution in the table, and dried using a roller dryer to obtain wood particles with a moisture content of 2%;

[0113]

[0114]

[0115] (IV) The sizing method of the wood particles is the same as that in Example 1;

[0116] (V) The humidity adjustment method of the wood particles is the same as that in Example 1;

[0117] (VI) The paving method of the wood particles is the same as that in Example 1;

[0118] (VII) Hot Pressing

[0119] The above pre-pressed board is hot pressed for 75 s. The specific hot pressing process is as follows: 230 °C, 480 bar, 25 s; 210 °C, 240 bar, 15 s; 190 °C, 100 bar, 15 s; 180 °C, 80 bar, 20 s.

[0120] To further illustrate the beneficial effects of the present invention, the following comparative examples are constructed.

[0121] Comparative Example 1

[0122] In step (V) of this comparative example, the addition amount of water is 2% of the weight of the wood particles; other conditions are the same as those in Example 2.

[0123] Comparative Example 2

[0124] In step (VII) of this comparative example, it is specifically: the above pre-pressed board is hot pressed for 75 s, the hot pressing temperature is 180 °C, the pressure is 520 bar, and then it is naturally cooled; other conditions are the same as those in Example 2.

[0125] Comparative Example 3

[0126] In step (VII) of this comparative example, it is specifically: the above pre-pressed board is hot pressed for 75 s, the hot pressing temperature is 180 °C, the pressure is 100 bar, and then it is naturally cooled; other conditions are the same as those in Example 2.

[0127] Then, performance tests are carried out on the wood particle veneer plywood prepared in the above Examples 1 - 3 and Comparative Examples 1 - 3. The relevant tests and results are as follows.

[0128] 1. Density

[0129] The cross-sectional density of the wood particle veneered plywood prepared in the above Examples 1-3 was tested, and the results are shown in Table 1. The plywood substrates prepared in the corresponding examples were used as controls.

[0130] As can be seen from Table 1, the densities of the pressed plates in this example and the control example are basically the same.

[0131] Table 1

[0132]

[0133] As can be seen from Table 1, the core veneers in Examples 1, 2, and 3 of the present invention are basically the same as the plywood substrate, while the surface layer has achieved obvious compression and densification, realizing asynchronous compression of the surface layer and the core layer. In Comparative Example 1, the moisture content of the surface layer is low, and the compression rate is significantly lower than that of Example 1, while the core layer also shows obvious compression; in Comparative Example 2, under the action of high pressure, the core layer and the surface layer are compressed synchronously; in Comparative Example 3, due to insufficient pressure, the densification degree of the surface layer does not meet the requirements.

[0134] 2. Immersion peeling performance

[0135] The test method for immersion peeling performance refers to the type II immersion peeling experiment in GB / T17657-2013 "Test Methods for Physical and Chemical Properties of Wood-Based Panels and Veneered Wood-Based Panels", and the results are shown in Figure 2-3 and Table 2.

[0136] Table 2

[0137]

[0138]

[0139] As can be seen from Table 2 and Figure 2-3 it can be known that the wood particle layer laid on the surface of the plywood by using the method of the present invention has good bonding performance with the plywood. Through the immersion peeling experiment, it is found that all are peeled, but the surface layer of the plates prepared in Comparative Examples 1-3 shows surface layer peeling or peeling.

[0140] In summary, the present invention uses plywood as the substrate and wood particles as the covering material. Wood particle layers are pressed on the upper and lower surfaces of the plywood and can be embedded into the veneer under the action of pressure to form a staggered cementation, improving the bonding strength between the two; applying glue evenly on the upper and lower surfaces of the prepared plywood, and then laying wood particles on the upper and lower surfaces of the plywood, which is equivalent to coating a layer of glue on the surface of the wood particles. After being embedded in the plywood, the firmness is better, improving the bonding strength. The immersion peeling strength between the wood particle layer and the veneer layer reaches the immersion peeling performance of type II panels.

[0141] The above are the preferred embodiments of the present invention. For those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A method for improving the impregnation peeling performance between the wood particle layer and the veneer layer of wood particle veneered plywood, characterized in that, Including: (1) Preparation of plywood The log is made into veneer, and then through sizing, assembling, hot pressing and thicknessing, plywood with a water content of 6 - 12% is obtained; (2) Sizing of plywood Uniformly coat the upper and lower surfaces of the plywood with an adhesive such as phenolic resin, urea-formaldehyde resin or melamine-urea-formaldehyde resin. The resin solids content of the adhesive used is 58-65%, and the sizing amount is 150-200 g / m 2 , and the flour addition amount of the phenolic resin, urea-formaldehyde resin or melamine-urea-formaldehyde resin is 30-40% of the weight of the adhesive; (3) Preparation of wood particles Wood is processed to obtain wood particles with the following particle size distribution in the table and dried to a moisture content of 1 - 3% by a roller dryer; (4) Sizing of wood particles Isocyanate is evenly sprayed onto the surface of the wood particles, and the sizing amount is 3 - 6% of the weight of the wood particles; (5) Humidity adjustment of wood particles A certain amount of water is evenly sprayed onto the surface of the wood particles, and the addition amount of water is 8 - 15% of the weight of the wood particles; (6) Laying of wood particles The wood particles in step (5) are divided into two parts and evenly laid on the upper and lower surfaces of the plywood; the slab is pre-pressed by online pre-pressing with a pressure of 2 - 5 MPa; (7) Hot pressing The pre-pressed board is hot-pressed. The hot-pressing time is 60 - 150 s, the hot-pressing temperature is 180 - 230 °C, and the pressure is gradually reduced from 480 - 520 bar to 80 - 100 bar, and then it is naturally cooled.

2. The method according to claim 1, wherein In the step (7), the hot-pressing process is specifically: 220 - 230 °C, 480 - 520 bar, 10 - 40 s; 210 °C, 330 - 240 bar, 15 - 40 s; 190 °C, 200 - 100 bar, 15 - 40 s; 180 °C, 100 - 80 bar, 15 - 60 s.

3. The method according to claim 1, wherein In the step (4), isocyanate is evenly sprayed onto the surface of the wood particles, the spraying pressure is 2.5 - 3.2 MPa, and the addition amount of the tackifier is 0.7% - 1% of the weight of the wood particles.

4. The method according to claim 1, wherein The step (6) is specifically: the sized wood particles are evenly divided into two parts and enter the paver respectively. The bottom layer of wood particles is laid in the bottom plate conveyor belt by the air laying method with a laying thickness of 1.5 - 2.0 cm, and then the plywood is placed above the bottom layer of wood particles; finally, the other half of the wood particles are also laid on the upper surface of the plywood by the air laying method with a laying thickness of 1.5 - 2.0 cm.

5. The method according to claim 1, wherein The wood particles are obtained by sawing or planing and are in a spindle-shaped structure with pointed ends or a cuboid structure.

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