Flame-retardant veneer wood-wool shaving board and preparation method thereof

Abstract

The invention discloses a flame-retardant veneer wood-wool shaving board and a preparation method thereof. The flame-retardant veneer wood-wool shaving board comprises a core board, an upper surface layer and a lower surface layer, wherein the upper surface layer and the lower surface layer are adhered to two sides of the core board through glue; the raw materials of the upper surface layer and the lower surface layer comprise fine materials, MDI glue and emulsified paraffin, and the fine materials comprise wood sawdust and / or sanding powder; the core plate comprises a core layer, and an upper secondary surface layer and a lower secondary surface layer which are arranged on two sides of the core layer; the raw materials of the core layer, the upper secondary surface layer and the lower secondary surface layer comprise wood wool and a silicate inorganic adhesive; the silicate inorganic adhesive is prepared from the following raw materials: a smoke suppressant, a binder, water, silicate cement, anhydrite, quick lime, fly ash and a waterproof agent; the wood wool of the core layer is paved in the transverse grain direction, and the wood wool of the upper secondary surface layer and the wood wool of the lower secondary surface layer are paved in the rift grain direction. According to the flame-retardant veneer wood-wool shaving board, the silicate inorganic adhesive is used as a cementing material of the core board, and the raw material of the core board is wood-wool, so that the flame-retardant veneer wood-wool shaving board has the characteristics of flame retardance, smoke suppression and high strength.

Description

Technical Field

[0001] The invention relates to the technical field of decorative panels, in particular to a flame-retardant decorative wood fiber particle board and a preparation method thereof. Background Art

[0002] At present, conventional oriented strand boards available on the market are all decorative boards, generally used as furniture boards or wall decoration boards, and do not have flame retardancy and antibacterial and mildew-proof properties. However, in some special places, such as shopping malls, hospitals, schools and other areas, requirements for flame retardancy and antibacterial and mildew-proof properties of decorative boards are being put forward. As people's living standards gradually improve, their requirements for the quality of life are also increasing simultaneously, and more and more customers are beginning to pursue functional and high-quality decorative boards.

[0003] In the prior art, there is research on adding cement to particleboard to make cement particleboard to achieve flame retardant properties. For example, "A flame retardant solid waste-based cement particleboard and its preparation method" is disclosed in Chinese patent literature, and its announcement number is CN114853431B. The cement particleboard is prepared from wood shavings, acidic phosphorus-containing silane modifier, electric furnace ash, high-silicon bauxite ultrafine powder, fast-setting and fast-hardening cement, ordinary Portland cement and other raw materials.

[0004] However, the existing cement particleboard is made by pressing a mixture of wood particles and cement system. This type of cement particleboard is very brittle and is prone to edge collapse of the finishing layer whether it is processed on-site or prefabricated in a factory. The cutting defect rate is high and the finishing effect is affected. Due to the characteristics of cement, its nail holding force is poor. In actual application, the threaded nail has poor nail holding force. After the steel nail is nailed into the board, it will cause the board to crack. Therefore, it is impossible to nail on the board surface to fix other items (such as wall lamps, televisions, air conditioners, etc.); the board density is usually more than 1300kg / m 3 , the weight is too heavy which affects the installation efficiency and other disadvantages. Summary of the invention

[0005] The present invention aims to overcome the above-mentioned problems existing in the particleboard in the prior art, and provides a flame-retardant wood fiber veneer particleboard and a preparation method thereof. A silicate inorganic adhesive is used as the cementitious material of the core board, and the raw material of the core board is wood fiber, so that the flame-retardant wood fiber veneer particleboard of the present invention has the characteristics of flame retardancy, smoke suppression and high strength.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: A flame-retardant veneerable wood fiber particleboard comprises a core board and an upper surface layer and a lower surface layer bonded to both sides of the core board by glue; the raw materials of the upper surface layer and the lower surface layer comprise: fine material, MDI glue and emulsified paraffin, and the fine material comprises wood sawdust and / or sanding powder; the core board comprises a core layer and an upper surface layer and a lower surface layer arranged on both sides of the core layer; the raw materials of the core layer, the upper surface layer and the lower surface layer comprise: wood fiber and a silicate inorganic adhesive; in parts by weight, the raw materials of the silicate inorganic adhesive comprise: 2-5 parts of a smoke suppressant, 5-8 parts of a binder, 40-60 parts of water, 40-70 parts of silicate cement, 2-8 parts of anhydrite, 2-5 parts of quicklime, 10-20 parts of fly ash, and 2-5 parts of a waterproofing agent; the wood fiber of the core layer is laid along the transverse direction of the grain, and the wood fiber of the upper surface layer and the lower surface layer is laid along the grain.

[0007] The structural characteristic of the present invention is that the particle board is divided into a five-layer structure including a core layer, upper and lower sub-surface layers, and upper and lower surface layers, wherein the adhesive used in the upper and lower surface layers is MDI, and MDI adhesive as an organic adhesive is formaldehyde-free adhesive. The organic adhesive used on the surface has organic toughness characteristics, so that the present invention and the traditional particle board have the same cutting properties, that is, there is no edge breakage when cutting. The present invention uses silicate inorganic adhesive as the cementitious material of the core board, so that the veneerable oriented structural particle board has the overall flame retardant and antibacterial and mildew-proof effects. The main reasons for the flame retardancy and antibacterial and mildew-proof effects are that silicate itself is a very good refractory material, which has the characteristic of being non-combustible. When mixed with wood chips as a cementitious material, the flame retardancy of the surface layer can be achieved, and the addition of a small amount of smoke suppressant can greatly reduce the amount of smoke released during its combustion process; and since salt substances such as hard gypsum and quicklime are added to the silicate inorganic adhesive, and the mixed material is alkaline after the reaction, since bacteria and mold cannot grow in a high-salt and alkaline environment, the surface layer has the characteristics of antibacterial and mildew-proof; and, after solidification, the cement material also has a strong waterproof effect, and its 24h water absorption thickness expansion rate and water impermeability can be comparable to those of traditional inorganic boards, so the decorative panel of the present invention can be used in humid environments.

[0008] At the same time, wood fibers are used in the core board instead of traditional wood shavings as the wood material. Different from the structure of traditional wood materials such as wood shavings, shavings, and wood powder, the long wood fibers have high mechanical properties and good dimensional stability after being bonded with silicate adhesive. The flame-retardant veneerable wood fiber particleboard of the present invention is prepared by mixing a wood fiber structure with a silicate adhesive in a certain proportion. Due to the filamentous structural characteristics of the wood fiber, the silicate adhesive can fully form a coating structure on the surface of the wood fiber during the mixing process. This structure in which the wood fiber is fully coated by the silicate adhesive makes it easier for the silicate adhesive to penetrate into the interlayer gap structure of the wood fiber cellulose (the wood fiber is dried, and the fiber cells are more likely to absorb the aqueous silicate adhesive until it is saturated). The original cellulose interlayer gap structure has weak transverse strength, but the transverse strength is significantly enhanced after the silicate adhesive is cured. The tobermorite whiskers formed by the cured silicate system present a needle-like structure and a criss-cross structure inside the wood cellulose cells. Due to the cement-based mechanical interlocking theory, this bonding method is difficult to separate the silicate cement from the wood fiber without destroying the wood fiber cells when subjected to external force, and the hydrogen bond force is much greater than that of conventional organic glue. The wood fibers coated with silicate adhesive generally present a crisscross mesh structure with other wood fibers. After the silicate adhesive is cured, the wood fibers are connected to each other, and the horizontal and vertical strengths are much higher than the strengths of conventional cement fiberboard or conventional particleboard. The upper and lower layers of the product of the present invention use fine materials and MDI glue as the main raw materials, which can ensure that the board will not collapse during the cutting process and will not affect the decorative effect. At the same time, the overall product density is 800-900kg / m 3 The density is moderate and it is easy to install. The weight of the silicate adhesive in the present invention only accounts for about 20% of the weight of the board, and most of the components are still wood materials. Therefore, the nail holding force of the present invention can reach the same strong nail holding force as that of conventional particleboards and other wood boards, realizing the processability of nailing and planing.

[0009] In the core board of the present invention, the wood fibers in the core layer and the upper and lower surface layers are laid in different directions, which can significantly improve the mechanical properties of the particle board. Since gaps will appear when wood fibers overlap, they cannot be completely flattened even after sanding, and the flatness is not enough to perform decorative surface bonding. Therefore, the present invention uses fine materials in the upper and lower surface layers. The fine materials in the upper and lower surface layers of the present invention rely on glue to play a bonding role during the bonding process with the core board, and the silicate adhesive in the core board plays an auxiliary role. After the silicate adhesive solidifies, the material itself has high hardness, high strength, and no formaldehyde. This makes the static bending strength, elastic modulus, internal bonding strength and other mechanical performance indicators of the flame-retardant wood fiber particle board in the present invention higher than those of conventional oriented structure particle boards that can be decorated, and can meet the use requirements of most places.

[0010] Preferably, the wood fibers in the core board have a width of 0.1-1 mm, a length of 10-300 mm, and a thickness of 0.1-1 mm; and the size of the fine materials in the upper surface layer and the lower surface layer is 60-120 meshes.

[0011] Preferably, in the core board, the mass ratio of the upper surface layer, the core layer and the lower surface layer is 2.5-3:4-5:2.5-3; in the core layer, the upper surface layer and the lower surface layer, the moisture content of the wood wool is 2-3wt%; the mass ratio of the silicate inorganic adhesive to the wood wool is 3-4:6-7, and in the silicate inorganic adhesive, the smoke suppressant is at least one of zinc borate, ammonium molybdate and antimony trioxide; the binder is at least one of silicone-modified acrylic emulsion, carboxymethyl cellulose and urea-formaldehyde resin; the waterproofing agent is at least one of emulsified paraffin and sodium methyl siliconate.

[0012] Preferably, in the upper surface layer and the lower surface layer, the mass of MDI glue is 2.5-5.0% of the mass of the fine material; the mass of emulsified paraffin is 1-2% of the mass of the fine material.

[0013] Preferably, the thickness of the core board is 10-13 mm; the thickness of the upper surface layer and the lower surface layer is 5-7 mm; the glue for bonding the core board to the upper surface layer and the lower surface layer is one of phenolic glue, melamine modified urea-formaldehyde glue, MDI glue, and water-based polyurethane glue.

[0014] The present invention also provides a method for preparing the flame-retardant veneerable wood fiber particleboard, comprising the following steps: (1) preparing a silicate adhesive, adding the prepared silicate inorganic adhesive to wood wool, and uniformly mixing to obtain raw materials for the core layer and the upper surface layer and the lower surface layer; (2) Directly paving the raw materials of each layer in the order of the lower surface layer, the core layer, and the upper surface layer, and then performing a hot pressing molding to obtain a core board; (3) Mixing MDI glue, emulsified paraffin and fine material to obtain raw materials for the upper surface layer and the lower surface layer; (4) Apply glue on the surface of the core board; (5) Laying the raw materials of the upper surface layer and the lower surface layer on the glue, and then performing secondary hot pressing molding; (6) Curing the board after the secondary hot pressing to obtain the flame-retardant veneerable wood fiber particleboard.

[0015] Preferably, in step (1), the preparation method of the silicate inorganic adhesive is: adding the smoke suppressant and the binder into water until they are completely dissolved, then adding silicate cement, anhydrite, quicklime, fly ash and a waterproofing agent, and mixing them evenly to obtain the silicate inorganic adhesive.

[0016] Preferably, in step (2), the unit pressure of the hot pressing molding is 3.5-5 MPa, the hot pressing temperature is 90-99° C., and the hot pressing time is 5-10 min.

[0017] Preferably, in step (4), the coating amount of glue is 220-250g / m 2 .

[0018] Preferably, in step (5), the unit pressure of the secondary hot pressing molding is 3.2-4.2 MPa, the hot pressing time is 2-4 min, and the hot pressing temperature is 180-190°C.

[0019] Preferably, the curing conditions in step (6) are: curing temperature 35±2° C., curing humidity 50-60%, and curing time 60-80 h.

[0020] Therefore, the present invention has the following beneficial effects: (1) Using silicate inorganic adhesive as the cementitious material of the core board makes the veneerable oriented structural particle board have the overall flame retardant and antibacterial and mildew-proof effects; (2) Wood wool is used in the core board instead of traditional wood shavings as the wood material, and the wood wool in the core layer and the upper and lower surface layers are laid in different directions, so that the flame-retardant veneerable wood wool particleboard of the present invention has very high mechanical properties and good dimensional stability. DETAILED DESCRIPTION

[0021] The present invention is further described below in conjunction with specific implementation methods.

[0022] In the present invention, unless otherwise specified, all equipment and raw materials can be purchased from the market or are commonly used in the industry. The methods in the following embodiments, unless otherwise specified, are conventional methods in the art.

[0023] Overall embodiment: A flame-retardant veneerable wood fiber particleboard comprises a core board and an upper surface layer and a lower surface layer bonded to both sides of the core board by glue; the raw materials of the upper surface layer and the lower surface layer comprise: fine material, MDI glue and emulsified paraffin, and the fine material comprises wood sawdust and / or sanding powder; the core board comprises a core layer and an upper surface layer and a lower surface layer arranged on both sides of the core layer; the raw materials of the core layer, the upper surface layer and the lower surface layer comprise: wood fiber and a silicate inorganic adhesive; in parts by weight, the raw materials of the silicate inorganic adhesive comprise: 2-5 parts of a smoke suppressant, 5-8 parts of a binder, 40-60 parts of water, 40-70 parts of silicate cement, 2-8 parts of anhydrite, 2-5 parts of quicklime, 10-20 parts of fly ash, and 2-5 parts of a waterproofing agent; the wood fiber of the core layer is laid along the transverse direction of the grain, and the wood fiber of the upper surface layer and the lower surface layer is laid along the grain.

[0024] As a specific implementation, the wood fibers in the core board have a width of 0.1-1 mm, a length of 10-300 mm, and a thickness of 0.1-1 mm; the size of the fine material in the upper surface layer and the lower surface layer is 60-120 mesh.

[0025] As a specific implementation manner, in the core board, the mass ratio of the upper surface layer, the core layer and the lower surface layer is 2.5-3:4-5:2.5-3; in the core layer, the upper surface layer and the lower surface layer, the moisture content of the wood wool is 2-3wt%; the mass ratio of the silicate inorganic adhesive to the wood wool is 3-4:6-7, and in the silicate inorganic adhesive, the smoke suppressant is at least one of zinc borate, ammonium molybdate, and antimony trioxide; the binder is at least one of silicone-modified acrylic emulsion, carboxymethyl cellulose, and urea-formaldehyde resin; the waterproofing agent is at least one of emulsified paraffin and sodium methyl siliconate.

[0026] As a specific implementation, in the upper surface layer and the lower surface layer, the mass of MDI glue is 2.5-5.0% of the mass of the fine material; the mass of emulsified paraffin is 1-2% of the mass of the fine material.

[0027] As a specific implementation, the thickness of the core board is 10-13mm; the thickness of the upper surface layer and the lower surface layer is 5-7mm; the glue bonding the core board and the upper surface layer and the lower surface layer is one of phenolic glue, melamine modified urea-formaldehyde glue, MDI glue, and water-based polyurethane glue.

[0028] The method for preparing the flame-retardant veneerable wood fiber particleboard comprises the following steps: (1) preparing a silicate adhesive, adding the prepared silicate inorganic adhesive to wood wool, and uniformly mixing to obtain raw materials for the core layer and the upper surface layer and the lower surface layer; (2) Directly paving the raw materials of each layer in the order of the lower surface layer, the core layer, and the upper surface layer, and then performing a hot pressing molding to obtain a core board; (3) Mixing MDI glue, emulsified paraffin and fine material to obtain raw materials for the upper surface layer and the lower surface layer; (4) Apply glue on the surface of the core board; (5) Laying the raw materials of the upper surface layer and the lower surface layer on the glue, and then performing secondary hot pressing molding; (6) Curing the board after the secondary hot pressing to obtain the flame-retardant veneerable wood fiber particleboard.

[0029] As a specific implementation, in step (1), the preparation method of the silicate inorganic adhesive is: add the smoke suppressant and the binder into water until they are completely dissolved, then add silicate cement, anhydrite, quicklime, fly ash and waterproofing agent, and mix them evenly to obtain the silicate inorganic adhesive.

[0030] As a specific implementation, in step (2), the unit pressure of the hot pressing molding is 3.5-5MPa, the hot pressing temperature is 90-99°C, and the hot pressing time is 5-10min.

[0031] As a specific implementation, in step (4), the coating amount of glue is 220-250g / m 2 .

[0032] As a specific implementation, in step (5), the unit pressure of the secondary hot pressing molding is 3.2-4.2 MPa, the hot pressing time is 2-4 min, and the hot pressing temperature is 180-190°C.

[0033] As a specific implementation, the curing conditions in step (6) are: curing temperature 35±2° C., curing humidity 50-60%, and curing time 60-80 h.

[0034] Embodiment 1: A flame-retardant wood fiber veneer particleboard, comprising a core board and an upper surface layer and a lower surface layer bonded to both sides of the core board by glue; the core board is 12 mm thick, and the upper and lower surface layers are both 6 mm thick; The core board comprises a core layer and an upper surface layer and a lower surface layer arranged on both sides of the core layer; the raw materials of the upper and lower surface layers include: fine material, MDI glue, and emulsified paraffin; the mass of MDI glue is 3.8% of the mass of the fine material, and the mass of emulsified paraffin is 1.5% of the mass of the fine material; the fine material is 100-mesh pine sawdust; The core layer raw materials include silicate inorganic adhesive and pine wood fibers in a mass ratio of 4:6; the width of the pine wood fibers is 0.5 mm, the length is 100 mm, and the thickness is 0.5 mm; in parts by weight, the raw materials of the silicate inorganic adhesive include: 2 parts of zinc borate, 5 parts of carboxymethyl cellulose, 40 parts of water, 40 parts of ordinary Portland cement clinker, 2 parts of anhydrite, 2 parts of quicklime, 10 parts of fly ash, and 2 parts of sodium methyl siliconate.

[0035] The method for preparing the flame-retardant veneerable wood fiber particleboard comprises the following steps: (1) Preparation of core board raw materials: Dry the pine wood fibers to a moisture content of 2%; (2) Mixing the core board raw materials: First, prepare the silicate inorganic adhesive: weigh the smoke suppressant zinc borate and the binder carboxymethyl cellulose in proportion, add water until they are completely dissolved, then add ordinary silicate cement clinker, anhydrite, quicklime, fly ash, and waterproofing agent sodium methylsiliconate and mix them evenly for use; then, mix the silicate inorganic adhesive and pine wood fibers evenly according to the mass ratio to obtain the core board raw materials; (3) Directional paving: Directly pave the raw materials of each layer in the order of the next surface layer, the core layer, and the upper surface layer. The paving direction is that the wood fibers of the upper and lower surface layers are laid along the grain direction, and the wood fibers of the core layer are laid across the grain direction. The mass ratio of the next surface layer: the core layer: the upper surface layer is 3:4:3. (4) Primary hot pressing: The paved slab is subjected to a primary hot pressing, with the unit pressure controlled at 4 MPa, the hot pressing temperature at 95 °C, and the hot pressing time at 8 min; (5) Mixing the raw materials for the surface layer: Add MDI glue and emulsified paraffin to the dried pine sawdust and mix them thoroughly to obtain the raw materials for the upper and lower surface layers; (6) Glue coating on core board: Roll 230g / m2 on the upper and lower surfaces of the core board respectively. 2 Melamine modified urea-formaldehyde adhesive; (7) Secondary paving: paving the raw materials of the upper surface layer and the lower surface layer obtained in step (5) on the glue; (8) Secondary hot pressing: The paved slab is subjected to secondary hot pressing, with the unit pressure controlled at 3.8 MPa, the hot pressing time at 3 min, and the hot pressing temperature at 185 °C; (9) Curing: The board after the secondary hot pressing is placed under the conditions of a temperature of 35° C. and a humidity of 55% for curing for 72 hours to obtain the flame-retardant veneerable wood fiber particleboard.

[0036] Embodiment 2: A flame-retardant wood fiber veneer particleboard, comprising a core board and an upper surface layer and a lower surface layer bonded to both sides of the core board by glue; the core board is 12 mm thick, and the upper and lower surface layers are both 5 mm thick; The core board comprises a core layer and an upper surface layer and a lower surface layer arranged on both sides of the core layer; the raw materials of the upper and lower surface layers include: fine material, MDI glue, and emulsified paraffin; the mass of the MDI glue is 2.5% of the mass of the pine sawdust, and the mass of the emulsified paraffin is 1% of the mass of the pine sawdust; the fine material is 100-mesh pine sawdust; The core layer raw materials include silicate inorganic adhesive and wood wool in a mass ratio of 4:6; the width of the pine wood wool is 0.5 mm, the length is 100 mm, and the thickness is 0.5 mm; in parts by weight, the raw materials of the silicate inorganic adhesive include: 5 parts of zinc borate, 8 parts of carboxymethyl cellulose, 60 parts of water, 70 parts of ordinary Portland cement clinker, 8 parts of anhydrite, 5 parts of quicklime, 20 parts of fly ash, and 5 parts of sodium methyl siliconate.

[0037] The method for preparing the flame-retardant veneerable wood fiber particleboard comprises the following steps: (1) Preparation of core board raw materials: Dry the pine wood fibers to a moisture content of 2%; (2) Mixing the core board raw materials: First, prepare the silicate inorganic adhesive: weigh the smoke suppressant zinc borate and the binder carboxymethyl cellulose in proportion, add water until they are completely dissolved, then add ordinary silicate cement clinker, anhydrite, quicklime, fly ash, and waterproofing agent sodium methylsiliconate and mix them evenly for use; then, mix the silicate inorganic adhesive and pine wood fibers evenly according to the mass ratio to obtain the core board raw materials; (3) Directional paving: Directly pave the raw materials of each layer in the order of the next surface layer, the core layer, and the upper surface layer. The paving direction is that the wood fibers of the upper and lower surface layers are laid along the grain direction, and the wood fibers of the core layer are laid across the grain direction. The mass ratio of the next surface layer: the core layer: the upper surface layer is 2.5:5:2.5. (4) Primary hot pressing: The paved slab is subjected to a primary hot pressing, with the unit pressure controlled at 3.5 MPa, the hot pressing temperature at 90°C, and the hot pressing time at 5 min; (5) Mixing of surface layer raw materials: Add MDI glue and emulsified paraffin to the dried pine sawdust and mix thoroughly to obtain the raw materials for the upper and lower surface layers. (6) Gluing the core board surface: Roll-coat 220g / m2 of melamine-modified urea-formaldehyde glue on the upper and lower surfaces of the core board respectively; (7) Secondary paving: paving the raw materials of the upper surface layer and the lower surface layer obtained in step (5) on the glue; (8) Secondary hot pressing: The paved slab is subjected to secondary hot pressing, with the unit pressure controlled to be 3 MPa, the hot pressing time to be 2 min, and the hot pressing temperature to be 180 °C; (9) Curing: The board after the secondary hot pressing is placed under the conditions of a temperature of 35° C. and a humidity of 55% for curing for 72 hours to obtain the flame-retardant veneerable wood fiber particleboard.

[0038] Embodiment 3: A flame-retardant wood fiber veneer particleboard, comprising a core board and an upper surface layer and a lower surface layer bonded to both sides of the core board by glue; the core board is 12 mm thick, and the upper and lower surface layers are both 7 mm thick; The core board comprises a core layer and an upper surface layer and a lower surface layer arranged on both sides of the core layer; the raw materials of the upper and lower surface layers include: fine material, MDI glue, and emulsified paraffin; the mass of the MDI glue is 5% of the mass of the pine sawdust, and the mass of the emulsified paraffin is 2% of the mass of the pine sawdust; the fine material is 100-mesh pine sawdust; The core layer raw materials include silicate inorganic adhesive and wood wool in a mass ratio of 3:7; the width of the pine wood wool is 0.5 mm, the length is 100 mm, and the thickness is 0.5 mm; in terms of weight, the raw materials of the silicate inorganic adhesive include: 3 parts of zinc borate, 7 parts of carboxymethyl cellulose, 50 parts of water, 60 parts of ordinary Portland cement clinker, 5 parts of anhydrite, 3 parts of quicklime, 15 parts of fly ash, and 3.5 parts of sodium methyl siliconate.

[0039] The method for preparing the flame-retardant veneerable wood fiber particleboard comprises the following steps: (1) Preparation of core board raw materials: Dry the pine wood fibers to a moisture content of 2%; (2) Mixing the core board raw materials: First, prepare the silicate inorganic adhesive: weigh the smoke suppressant zinc borate and the binder carboxymethyl cellulose in proportion, add water until they are completely dissolved, then add ordinary silicate cement clinker, anhydrite, quicklime, fly ash, and waterproofing agent sodium methylsiliconate and mix them evenly for use; then, mix the silicate inorganic adhesive and pine wood fibers evenly according to the mass ratio to obtain the core board raw materials; (3) Directional paving: Directly pave the raw materials of each layer in the order of the next surface layer, the core layer, and the upper surface layer. The paving direction is that the wood fibers of the upper and lower surface layers are laid along the grain direction, and the wood fibers of the core layer are laid across the grain direction. The mass ratio of the next surface layer: the core layer: the upper surface layer is 3:4:3. (4) Primary hot pressing: The paved slab is subjected to a primary hot pressing, with the unit pressure controlled at 5 MPa, the hot pressing temperature at 99°C, and the hot pressing time at 10 min; (5) Mixing of surface layer raw materials: Add MDI glue and emulsified paraffin to the dried pine sawdust and mix thoroughly to obtain the raw materials for the upper and lower surface layers. (6) Gluing the core board surface: Roll-coat 250g / m2 of melamine-modified urea-formaldehyde glue on the upper and lower surfaces of the core board respectively; (7) Secondary paving: paving the raw materials of the upper surface layer and the lower surface layer obtained in step (5) on the glue; (8) Secondary hot pressing: The paved slab is hot pressed, with the unit pressure controlled to be 4.2 MPa, the hot pressing time to be 4 min, and the hot pressing temperature to be 190 °C; (9) Curing: The board after the secondary hot pressing is placed under the conditions of a temperature of 35° C. and a humidity of 55% for curing for 72 hours to obtain the flame-retardant veneerable wood fiber particleboard.

[0040] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that the raw materials of the core layer include MDI glue and pine wood fibers, and the amount of MDI glue used is 3.8% of the mass of the pine wood fibers; during preparation, the first hot pressing conditions and the second hot pressing conditions are the same as those in step (8) of Example 1; and the rest are the same as in Example 1.

[0041] Comparative Example 2: The difference between Comparative Example 2 and Example 1 is that the raw materials of the core layer include MDI glue, fine material and commercially available wood flame retardant, the amount of MDI glue used is 3.8% of the mass of pine wood fiber, and the mass ratio of pine wood fiber to flame retardant is 10:1; during preparation, the first hot pressing conditions and the second hot pressing conditions are the same as those in step (8) of Example 1; the rest are the same as in Example 1.

[0042] Comparative Example 3: The difference between Comparative Example 3 and Example 1 is that the raw materials of the upper and lower surface layers include silicate inorganic adhesive and pine wood fibers in a mass ratio of 4:6; the rest are the same as in Example 1.

[0043] The particleboards prepared in the above embodiments and comparative examples were subjected to a combustion test (GB / T 20284-2006) and a limiting oxygen index test (GB / T 2406-2009). The results are shown in Table 1.

[0044] Table 1: Flame retardant performance test results.

[0045] The strength of the particleboards prepared in the above embodiments and comparative examples was tested (GB / T 41716-2022), and the results are shown in Table 2.

[0046] Table 2: Strength test results.

[0047] It can be seen from the test results of Table 1 and Table 2 that the flame retardant properties of the particleboards obtained by the method of the present invention in Examples 1-3 can all reach the B1-B grade required by the national standard. According to the principle that combustion requires contact with oxygen combined with the actual detection method, it can be concluded that the surface layer material is exposed to a large area of ​​oxygen in the air, which directly affects the monomer combustion and oxygen index detection results. In Examples 1-3, a silicate inorganic adhesive was used to perform flame retardant treatment on the surface of the veneerable particleboard, and the A1 grade non-combustible property of the silicate cement material itself was used to achieve the flame retardant treatment of the entire particleboard. In Comparative Example 1, the core layer uses conventional MDI adhesive, and the particleboard produced has no flame retardant properties; in Comparative Example 2, wood flame retardants are added to the surface fine material of the particleboard. Such flame retardants are mostly nitrogen-phosphorus flame retardants, which mainly rely on the principle of releasing gas and water analysis when heated to achieve flame retardant function. After adding, the flame retardant of the board can be improved to a certain extent, but because the flame retardant crystals are salt substances and are easy to absorb water, this will cause the board to corrode the metal, and long-term exposure to the air to absorb water will cause the board to absorb moisture, affecting the use effect. In Comparative Example 3, silicate inorganic adhesives are also used in the upper and lower surface layers. In the absence of an interface agent, the surface adhesion of the finishing layer to the board surface is not strong, resulting in unqualified surface bonding strength of the finishing layer, and the board produced in this way will have edge collapse after cutting, which is not in line with market reality.

Claims

1. A flame-retardant veneerable wood fiber particleboard, characterized in that: It includes a core board and an upper surface layer and a lower surface layer bonded to both sides of the core board by glue; The raw materials of the upper surface layer and the lower surface layer include: fine material, MDI glue and emulsified paraffin, and the fine material includes wood sawdust and / or sanding powder; The core board includes a core layer and an upper surface layer and a lower surface layer arranged on both sides of the core layer; the raw materials of the core layer, the upper surface layer and the lower surface layer include: wood wool and silicate inorganic adhesive; in parts by weight, the raw materials of the silicate inorganic adhesive include: 2-5 parts of smoke suppressant, 5-8 parts of binder, 40-60 parts of water, 40-70 parts of silicate cement, 2-8 parts of hard gypsum, 2-5 parts of quicklime, 10-20 parts of fly ash, and 2-5 parts of waterproofing agent; the wood wool of the core layer is laid along the transverse direction of the grain, and the wood wool of the upper surface layer and the lower surface layer is laid along the grain direction.

2. The flame-retardant veneerable wood fiber particleboard according to claim 1 is characterized in that: The wood fibers in the core board have a width of 0.1-1 mm, a length of 10-300 mm, and a thickness of 0.1-1 mm; the size of the fine material in the upper surface layer and the lower surface layer is 60-120 meshes.

3. The flame-retardant veneerable wood fiber particleboard according to claim 1, characterized in that: In the core board, the mass ratio of the upper surface layer, the core layer and the lower surface layer is 2.5-3:4-5:2.5-3; in the core layer, the upper surface layer and the lower surface layer, the moisture content of the wood fibers is 2-3wt%; the mass ratio of the silicate inorganic adhesive to the wood fibers is 3-4:6-7, and in the silicate inorganic adhesive, the smoke suppressant is at least one of zinc borate, ammonium molybdate and antimony trioxide; the binder is at least one of silicone-modified acrylic emulsion, carboxymethyl cellulose and urea-formaldehyde resin; the waterproofing agent is at least one of emulsified paraffin and sodium methyl siliconate.

4. The flame-retardant veneerable wood fiber particleboard according to claim 1, characterized in that: In the upper surface layer and the lower surface layer, the mass of MDI glue is 2.5-5.0% of the mass of the fine material; the mass of emulsified paraffin is 1-2% of the mass of the fine material.

5. The flame-retardant veneerable wood fiber particleboard according to claim 1, characterized in that: The thickness of the core board is 10-13 mm; the thickness of the upper surface layer and the lower surface layer is 5-7 mm; the glue for bonding the core board and the upper surface layer and the lower surface layer is one of phenolic glue, melamine modified urea-formaldehyde glue, MDI glue, and water-based polyurethane glue.

6. A method for preparing the flame-retardant veneerable wood fiber particleboard according to any one of claims 1 to 5, characterized in that: The steps include: (1) preparing a silicate adhesive, adding the prepared silicate inorganic adhesive to wood wool, and uniformly mixing them to obtain raw materials for the core layer and the upper surface layer and the lower surface layer; (2) Directly laying the raw materials of each layer in the order of the lower surface layer, the core layer, and the upper surface layer, and then hot pressing and forming the raw materials once to obtain the core board; (3) Mixing MDI glue, emulsified paraffin and fine materials to obtain raw materials for the upper surface layer and the lower surface layer; (4) Apply glue on the surface of the core board; (5) Laying the raw materials of the upper surface layer and the lower surface layer on the glue, and then performing secondary hot pressing molding; (6) Maintain the plate after secondary hot pressing.

7. The method for preparing the flame-retardant veneerable wood fiber particleboard according to claim 6, characterized in that: In step (1), the preparation method of the silicate inorganic adhesive is: adding a smoke suppressant and a binder into water until they are completely dissolved, then adding silicate cement, anhydrite, quicklime, fly ash and a waterproofing agent, and mixing them evenly to obtain the silicate inorganic adhesive.

8. The method for preparing the flame-retardant veneerable wood fiber particleboard according to claim 6, characterized in that: In step (2), the unit pressure of the hot pressing molding is 3.5-5 MPa, the hot pressing temperature is 90-99° C., and the hot pressing time is 5-10 min.

9. The method for preparing the flame-retardant veneerable wood fiber particleboard according to claim 6, characterized in that: In step (5), the unit pressure of the secondary hot pressing molding is 3.2-4.2 MPa, the hot pressing time is 2-4 min, and the hot pressing temperature is 180-190°C.

10. The method for preparing the flame-retardant veneerable wood fiber particleboard according to claim 6, characterized in that: The curing conditions in step (6) are: curing temperature 35±2°C, curing humidity 50-60%, and curing time 60-80h.

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