Formaldehyde-free shaving board as well as preparation method and application thereof

Abstract

The invention provides a formaldehyde-free shaving board and a preparation method and application thereof. The formaldehyde-free shaving board comprises an upper surface layer, a core layer and a lower surface layer. Wherein the raw materials of the upper surface layer and the lower surface layer comprise wood shavings, an adhesive, a reinforcing agent and water; the raw materials of the core layer comprise wood shavings, an adhesive, a curing agent and water; wherein the adhesive is prepared from isocyanate; the reinforcing agent is selected from a compound of which the end groups simultaneously comprise siloxy and amino. The surface reinforcing agent can reduce the situation that a steel belt is adhered to the surface of the plate blank and improve the surface curing speed, so that the purpose of improving the surface quality of the plate blank is achieved; and the core layer curing agent can improve the curing speed of the adhesive isocyanate, so that the production efficiency is improved. The problem that the production difficulty of a hot-pressing section of an isocyanate formaldehyde-free shaving board is higher than that of a urea-formaldehyde resin shaving board is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of particleboards, and relates to a formaldehyde-free particleboard, a preparation method thereof and an application thereof. Background Art

[0002] The traditional adhesives in the wood-based panel industry are "three formaldehyde adhesives", namely: urea-formaldehyde resin adhesive, phenolic resin adhesive, and melamine-formaldehyde resin adhesive. After these three adhesives are used to produce wood-based panels, the panels will contain free formaldehyde, which will gradually be released into the environment, pollute the indoor air, and damage human health. Currently, for wood-based panels using "three formaldehyde adhesives", the formaldehyde release amount of the panels is mainly reduced by optimizing the adhesive formula (such as changing the ratio of urea to formaldehyde), adding formaldehyde scavengers, etc. However, these methods still cannot achieve formaldehyde-free addition.

[0003] Isocyanates have been widely used in other industries. It has high bonding strength, strong water resistance, and does not contain formaldehyde. Good physical and mechanical properties can be obtained under the condition that the sizing amount is much lower than that of "three formaldehyde adhesives". Although isocyanate adhesives have the above advantages, there are still some problems to be solved in the production process of formaldehyde-free particleboards. For example, in the production of formaldehyde-free wood-based panels with isocyanate as the adhesive, there are still problems such as difficult demolding, poor surface quality of the board blank, and affecting subsequent processing.

[0004] CN114181659A discloses a formaldehyde-free adhesive, which mainly improves the problem of slow curing speed, but fails to solve the problems of poor surface quality of the finished board and difficult demolding. CN115141343A discloses a formaldehyde-free particleboard additive, whose main function is to maintain excellent bonding performance and mechanical properties while further improving the production efficiency of formaldehyde-free wood-based panels. Similarly, it does not improve the problems of poor surface quality of the finished board and difficult demolding.

[0005] In summary, currently, in the production of formaldehyde-free wood-based panels with isocyanate as the adhesive, there are still problems such as difficult demolding, poor surface quality of the board blank, and affecting subsequent processing, which urgently need to be solved. Summary of the Invention

[0006] Aiming at the deficiencies of the prior art, one of the purposes of the present invention is to provide a formaldehyde-free particleboard. This formaldehyde-free particleboard not only achieves formaldehyde-free addition, but also under the same process conditions, the dosage of the demolding agent for the steel belt is significantly reduced, almost no steel belt scale is generated, the surface quality of the board blank is improved, and the appearance of the board is improved. After lamination, the dimensional stability is good, and there will be no cracking problem due to the too large difference in the deformation ability between the substrate and the laminate.

[0007] The second object of the present invention is to provide a method for preparing the formaldehyde-free particleboard. By adding a reinforcing agent to the surface layer, the situation of the slab sticking to the steel belt on the surface can be reduced, and the curing speed of the surface layer can be increased; at the same time, by adding a curing agent to the core layer, the curing speed of the adhesive isocyanate can be increased, thereby improving the production efficiency. The problem that the production difficulty of the hot pressing section of the isocyanate-based formaldehyde-free particleboard is higher than that of the urea-formaldehyde resin particleboard is improved.

[0008] The third object of the present invention is to provide the application of the formaldehyde-free particleboard in the field of furniture boards.

[0009] To achieve this purpose, the present invention adopts the following technical solutions:

[0010] In the first aspect, the present invention provides a formaldehyde-free particleboard, which includes an upper surface layer, a core layer, and a lower surface layer; wherein, the raw materials of the upper surface layer and the lower surface layer include wood particles, an adhesive, a reinforcing agent, and water; the raw materials of the core layer include wood particles, an adhesive, a curing agent, and water;

[0011] Among them, the adhesive contains isocyanate; the reinforcing agent is selected from compounds with both siloxy groups and amino groups at the end groups.

[0012] In the present invention, the reinforcing agent is selected from compounds with a siloxy group at one end and an amino group at the other end. The siloxy end group can provide mold release properties, and the amino end group can react with isocyanate to increase the curing speed of the adhesive;

[0013] Preferably, the reinforcing agent is selected from one or more of 1,3-bis(aminopropyl)-1,1,3,3-tetramethyldisiloxane, 1,3-bis(2-aminoethylaminomethyl)tetramethyldisiloxane, dimethyl-3-[(2-aminoethyl)amino]propylmethyl(siloxane and polysiloxane), more preferably one or more of 1,3-bis(aminopropyl)-1,1,3,3-tetramethyldisiloxane, 1,3-bis(2-aminoethylaminomethyl)tetramethyldisiloxane, and further preferably 1,3-bis(aminopropyl)-1,1,3,3-tetramethyldisiloxane.

[0014] In the present invention, the curing agent can be a conventional curing agent type applicable in the field of particleboards, such as amine curing agents, etc., preferably aliphatic amine catalysts, more preferably one or more of triethylamine, triethylenediamine, N,N-dimethylcyclohexylamine, N,N-dimethylhexadecylamine, diethylenetriamine, and further preferably N,N-dimethylcyclohexylamine.

[0015] In the present invention, the adhesive contains isocyanate, referring to the adhesives of the upper surface layer, the lower surface layer, and the core material;

[0016] Preferably, the functionality of the isocyanate is 2.6-2.7, such as 2.6, 2.7, etc.;

[0017] Preferably, the -NCO value of the isocyanate is 25 - 35 wt%, such as 25 wt%, 27 wt%, 30 wt%, 32 wt%, 35 wt%, etc.;

[0018] Preferably, the isocyanate comprises polydiphenylmethane diisocyanate, preferably Wanhua Chemical CW20, 9132FC, 9131FC.

[0019] There is no particular requirement for the material of the wood shavings of the present invention. For example, it can be poplar, eucalyptus, fir, miscellaneous wood, etc. commonly used in the field of particleboard. There is also no clear requirement for the morphological dimensions of the wood shavings. For example, it can be a narrow and long thin slice of (0.8 - 12) mm * (0.8 - 1.2) mm * (0.1 - 0.6) mm;

[0020] Preferably, the raw materials of the upper surface layer and the lower surface layer are fine wood shavings, and the raw materials of the core layer are coarse wood shavings; specifically, the wood shavings can be separated by air flow to obtain fine surface layer wood shavings and coarse core layer wood shavings. The present invention does not specifically limit the specific dimensions of the fine wood shavings and the coarse wood shavings. The relatively fine material obtained after screening can be used as the fine wood shavings, such as having dimensions of (0.8 - 1) mm * (0.8 - 1) mm * (0.1 - 0.4) mm, and the relatively coarse material can be used as the coarse wood shavings, such as having dimensions of (1 - 12) mm * (1 - 1.2) mm * (0.4 - 0.6) mm.

[0021] In one embodiment of the present invention, the raw materials of the upper surface layer and the lower surface layer include, by weight parts:

[0022]

[0023] In one embodiment of the present invention, the raw materials of the core layer include, by weight parts:

[0024]

[0025] In one embodiment of the present invention, the mass ratio of the upper surface layer, the core layer, and the lower surface layer is 1:(2.5 - 4):1, such as 1:2.5:1, 1:2.7:1, 1:3:1, 1:3.2:1, 1:3.5:1, 1:3.8:1, 1:4:1, etc., preferably 1:(3 - 3.5):1.

[0026] In a second aspect, the present invention provides a method for preparing the formaldehyde-free particleboard. For the relevant operations, process conditions, and devices used in the preparation method of the present invention, corresponding conventional selections in the art can be adopted, and there are no special restrictions. Those skilled in the art can optimize based on the known processes in the prior art according to actual needs. Specifically, for example, the preparation can be carried out by the methods listed in the following embodiments of the present invention.

[0027] Specifically, a method for preparing a formaldehyde-free particleboard includes the following steps:

[0028] S1: Dry the wood particles, and sort the fine wood particles and the coarse wood particles.

[0029] S2: Apply the binder on the fine wood particles, and then add the reinforcing agent and water to obtain the preparatory materials for the upper surface layer and the lower surface layer respectively.

[0030] S3: Apply the binder and the curing agent on the coarse wood particles, and then add water to obtain the preparatory material for the core layer.

[0031] S4: Lay the preparatory material for the lower surface layer, the preparatory material for the core layer, and the preparatory material for the upper surface layer in sequence, and perform hot pressing to obtain the formaldehyde-free particleboard.

[0032] In an embodiment of the present invention, the wood particles in step S1 are dried to a moisture content ≤ 2 wt%.

[0033] In an embodiment of the present invention, for the hot pressing in step S4, the temperature is 180 - 250 °C, the pressure is 0.5 - 6 MpaG, and the time is 80 - 140 s.

[0034] In a third aspect, the present invention provides the use of the formaldehyde-free particleboard.

[0035] The particleboard of the present invention is the formaldehyde-free particleboard described above, or the formaldehyde-free particleboard prepared by the above method, and the particleboard is used for furniture boards.

[0036] Compared with the prior art, the present invention has at least the following beneficial effects:

[0037] (1) In the preparation raw materials of the surface layer of the formaldehyde-free particleboard of the present invention, it simultaneously includes the binder isocyanate and the reinforcing agent. The surface layer reinforcing agent can reduce the situation of the slab sticking to the steel belt on the surface, improve the surface curing speed of the surface layer, and thus achieve the purpose of improving the surface quality of the slab.

[0038] (2) The particleboard provided by the present invention not only achieves formaldehyde-free addition, but also, under the same process conditions, significantly reduces the dosage of the mold release agent for the steel belt, hardly generates steel belt scale, improves the service life of the steel belt, and improves the appearance quality of the board. After lamination, the dimensional stability is good, and no cracking problem will occur due to the too large difference in deformation ability between the substrate and the laminate. Detailed implementation manners

[0039] The technical solutions of the present invention will be further described below through specific implementation manners. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0040] In the embodiments and comparative examples of the present invention, the sources of the main raw materials used are as shown in Table 1 below. If there is no special description for other raw materials and reagents, they are all obtained through commercial channels on the market:

[0041] Table 1

[0042]

[0043]

[0044] Example 1

[0045] In this example, a formaldehyde-free particleboard is provided, which includes an upper surface layer, a core layer, and a lower surface layer. Among them, the raw materials of the upper surface layer and the lower surface layer both include the following components:

[0046]

[0047] The raw materials of the core layer include the following components:

[0048]

[0049] Among them, the brand of the isocyanate is CW20, the curing agent is N,N-dimethylcyclohexylamine, the reinforcing agent is 1,3-bis(aminopropyl)-1,1,3,3-tetramethyldisiloxane, and the mass ratio of the upper surface layer, the core layer, and the lower surface layer is 1:3:1.

[0050] The preparation method includes the following steps:

[0051] (1) Put the wood particles into an oven at 120 °C and dry them to a moisture content of 2 wt%, and separate the wood particles by air flow to obtain fine surface wood materials and coarse core wood materials;

[0052] (2) Pour the fine wood particles into a glue mixer, apply the isocyanate using a compressed air spray gun, and then add the reinforcing agent and water to obtain the preliminary materials for the upper surface layer and the lower surface layer respectively;

[0053] (3) Pour the coarse wood shavings into a glue mixer, apply isocyanate and curing agent using a compressed air spray gun, and then add water to obtain the core layer preparation material;

[0054] (4) Put the preparation materials of the lower surface layer, the core layer, and the upper surface layer into a paving box in sequence. After paving and forming, compact it to discharge the air in the middle, and then put it into a hot press. Heat and cure it at 230 °C to obtain the formaldehyde-free particleboard.

[0055] Among them, the specific hot pressing process is as follows:

[0056] Spraying amount of mold release agent on the steel belt surface: 0.1 g / m 2

[0057] The hot pressing factor is 6 s / mm, and the hot pressing is carried out in sequence according to the following pressure and time: 4 MPa(G) / 20 s + 3.5 MPa(G) / 25 s + 3 MPa(G) / 15 s + 2 MPa(G) / 15 s + 1.5 MPa(G) / 20 s + 0.5 MPa(G) / 13 s.

[0058] Example 2

[0059] In this example, a formaldehyde-free particleboard is provided, which includes an upper surface layer, a core layer, and a lower surface layer. Among them, the preparation raw materials of the upper surface layer and the lower surface layer both include the following components:

[0060]

[0061] The raw materials of the core layer include the following components:

[0062]

[0063] Among them, the brand of isocyanate is CW20, the curing agent is N, N-dimethylcyclohexylamine, the reinforcing agent is 1,3-bis(aminopropyl)-1,1,3,3-tetramethyldisiloxane, and the mass ratio of the upper surface layer, the core layer, and the lower surface layer is 1:3:1.

[0064] The preparation method is the same as that of Example 1.

[0065] Example 3

[0066] In this example, a formaldehyde-free particleboard is provided, which includes an upper surface layer, a core layer, and a lower surface layer. Among them, the preparation raw materials of the upper surface layer and the lower surface layer both include the following components:

[0067]

[0068] The raw materials of the core layer include the following components:

[0069]

[0070] Among them, the brand of the isocyanate is CW20, the curing agent is N, N-dimethylcyclohexylamine, the reinforcing agent is 1,3-bis(aminopropyl)-1,1,3,3-tetramethyldisiloxane, and the mass ratio of the upper surface layer, the core layer and the lower surface layer is 1:3:1.

[0071] The preparation method is the same as that of Example 1.

[0072] Example 4

[0073] In this example, an aldehyde-free particleboard is provided, which includes an upper surface layer, a core layer and a lower surface layer. Among them, the raw materials for preparing the upper surface layer and the lower surface layer both include the following components:

[0074]

[0075] The raw materials for preparing the core layer include the following components:

[0076]

[0077] Among them, the brand of the isocyanate is CW20, the curing agent is N, N-dimethylcyclohexylamine, the reinforcing agent is 1,3-bis(2-aminoethylaminomethyl)tetramethyldisiloxane, and the mass ratio of the upper surface layer, the core layer and the lower surface layer is 1:3.5:1.

[0078] The preparation method refers to Example 1, and the only difference is that the wooden particles are put into an oven at 120 °C and dried to a moisture content of 0.5 wt%.

[0079] Example 5

[0080] In this example, an aldehyde-free particleboard is provided, which includes an upper surface layer, a core layer and a lower surface layer. Among them, the raw materials for preparing the upper surface layer and the lower surface layer both include the following components:

[0081]

[0082] The raw materials for preparing the core layer include the following components:

[0083]

[0084] Among them, the brand of the isocyanate is CW20, the curing agent is N, N-dimethylcyclohexylamine, the reinforcing agent is 1,3-bis(2-aminoethylaminomethyl)tetramethyldisiloxane, and the mass ratio of the upper surface layer, the core layer and the lower surface layer is 1:3.5:1.

[0085] The preparation method refers to Example 1, and the only difference is that the wooden particles are put into an oven at 120 °C and dried to a moisture content of 0.5 wt%.

[0086] Example 6

[0087] In this embodiment, a formaldehyde-free particleboard is provided, which includes an upper surface layer, a core layer, and a lower surface layer. Among them, the raw materials for preparing the upper surface layer and the lower surface layer both include the following components:

[0088]

[0089] The raw materials for preparing the core layer include the following components:

[0090]

[0091] Among them, the grade of the isocyanate is CW20, the curing agent is N,N-dimethylcyclohexylamine, the reinforcing agent is 1,3-bis(2-aminoethylaminomethyl)tetramethyldisiloxane, and the mass ratio of the upper surface layer, the core layer, and the lower surface layer is 1:3.5:1.

[0092] The preparation method refers to Example 1, with the only difference being that the wood particles are placed in an oven at 120 °C and dried to a moisture content of 0.5 wt%.

[0093] Example 7

[0094] In this embodiment, a formaldehyde-free particleboard is provided, which includes an upper surface layer, a core layer, and a lower surface layer. Among them, the raw materials for preparing the upper surface layer and the lower surface layer both include the following components:

[0095]

[0096] The raw materials for preparing the core layer include the following components:

[0097]

[0098] Among them, the grade of the isocyanate is CW20, the curing agent is N,N-dimethylcyclohexylamine, the reinforcing agent is dimethyl-3-[(2-aminoethyl)amino]propylmethyl (siloxanes and silicones), and the mass ratio of the upper surface layer, the core layer, and the lower surface layer is 1:3:1.

[0099] The preparation method refers to Example 1, with the only difference being that the wood particles are placed in an oven at 120 °C and dried to a moisture content of 1 wt%.

[0100] Example 8

[0101] In this embodiment, a formaldehyde-free particleboard is provided, which includes an upper surface layer, a core layer, and a lower surface layer. Among them, the raw materials for preparing the upper surface layer and the lower surface layer both include the following components:

[0102]

[0103] The raw materials for preparing the core layer include the following components:

[0104]

[0105] Among them, the brand of the isocyanate is CW20, the curing agent is N, N-dimethylcyclohexylamine, the reinforcing agent is dimethyl-3-[(2-aminoethyl)amino]propylmethyl (siloxane and polysiloxane), and the mass ratio of the upper surface layer, the core layer and the lower surface layer is 1:3:1.

[0106] The preparation method refers to Example 1, with the only difference being that the wood shavings are placed in an oven at 120 °C and dried to a moisture content of 1 wt%.

[0107] Example 9

[0108] In this example, a formaldehyde-free particleboard is provided, which includes an upper surface layer, a core layer and a lower surface layer. Among them, the preparation raw materials of the upper surface layer and the lower surface layer both include the following components:

[0109]

[0110] The preparation raw materials of the core layer include the following components:

[0111]

[0112] Among them, the brand of the isocyanate is CW20, the curing agent is N, N-dimethylcyclohexylamine, the reinforcing agent is dimethyl-3-[(2-aminoethyl)amino]propylmethyl (siloxane and polysiloxane), and the mass ratio of the upper surface layer, the core layer and the lower surface layer is 1:3:1.

[0113] The preparation method refers to Example 1, with the only difference being that the wood shavings are placed in an oven at 120 °C and dried to a moisture content of 1 wt% before the preparation experiment.

[0114] Comparative Example 1

[0115] The difference between this comparative example and Example 1 is only that the reinforcing agent is not added to the preparation raw materials of the surface layer, and other raw materials and parameters remain unchanged.

[0116] The remaining preparation method is the same as that of Example 1.

[0117] Comparative Example 2

[0118] The difference between this comparative example and Example 1 is only that the reinforcing agent in the preparation raw materials of the surface layer is replaced with an equal mass of hexamethyldisiloxane, and other raw materials and parameters remain unchanged.

[0119] The preparation method is the same as that of Example 1.

[0120] The performance of the particleboards prepared in the examples and the comparative examples was tested, and the test method was as follows:

[0121] (1) 2-hour water absorption thickness swelling rate: Test according to Test Method 4.4 Water Absorption Thickness Swelling Rate Determination Method 1 specified in GB / T 17657-2013;

[0122] (2) Modulus of rupture and modulus of elasticity: Test according to Test Method 4.7 Modulus of Rupture and Modulus of Elasticity Determination (Three-point Bending) specified in GB / T 17657-2013;

[0123] (3) Internal bond strength: Test according to Test Method 4.11 Internal Gluing (Bonding) Strength Determination specified in GB / T 17657-2013;

[0124] (4) Surface bond strength: Test according to Test Method 4.15 Surface Gluing Strength Determination specified in GB / T 17657-2013;

[0125] (5) Physical and mechanical property requirements: Test according to Part 3 of GB / T 4897.3-2003 Particleboard: Requirements for boards used in furniture and interior decoration for use in the dry state: For boards in the nominal thickness range of 13 - 20 mm, modulus of rupture ≥ 13 Mpa, modulus of elasticity ≥ 1600 Mpa, internal bond strength ≥ 0.35 Mpa, surface bond strength ≥ 0.8 Mpa;

[0126] (6) Continuous demolding times: After spraying the release agent on the steel belt, conduct continuous hot pressing experiments for particleboard production. If the nth board blank sticks to the steel belt, stop the hot pressing. The demolding times are recorded as n - 1.

[0127] The hot press used in the experimental process is the universal experimental press of Wuxi Dipu, and the instrument used for testing performance is the high-speed rail universal tensile testing machine.

[0128] The thickness and performance test results of the particleboards provided by the examples and comparative examples are shown in Table 2.

[0129] Table 2

[0130]

[0131] As can be seen from Table 2, the internal bond strength, modulus of rupture, modulus of elasticity, and surface gluing strength of the formaldehyde-free particleboards provided by Examples 1 - 9 of the present invention can all meet the national standard requirements.

[0132] With the increase in the dosage of the reinforcing agent in the present invention, the demolding property gradually increases, and the surface gluing strength gradually becomes larger.

[0133] The present invention illustrates the formaldehyde-free particleboard and its preparation method and application through the above embodiments. However, the present invention is not limited to the above embodiments, that is, it does not mean that the present invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvement of the present invention, the equivalent substitution of each raw material of the present invention's products, the addition of auxiliary components, the selection of specific methods, etc., all fall within the protection scope and the disclosure scope of the present invention.

Claims

1. An aldehyde-free particleboard, characterized in that, The formaldehyde-free particleboard includes an upper surface layer, a core layer, and a lower surface layer; wherein, the raw materials of the upper surface layer and the lower surface layer include wood particles, an adhesive, a reinforcing agent, and water; the raw materials of the core layer include wood particles, an adhesive, a curing agent, and water. Among them, the adhesive includes isocyanate; the reinforcing agent is selected from compounds with both siloxy groups and amino groups at the end groups.

2. The formaldehyde-free particleboard according to claim 1, wherein The reinforcing agent is selected from compounds with a siloxy group at one end and an amino group at the other end; and / or The reinforcing agent is selected from one or more of 1,3-bis(aminopropyl)-1,1,3,3-tetramethyldisiloxane, 1,3-bis(2-aminoethylaminomethyl)tetramethyldisiloxane, dimethyl-3-[(2-aminoethyl)amino]propylmethyl(siloxane and polysiloxane), more preferably one or more of 1,3-bis(aminopropyl)-1,1,3,3-tetramethyldisiloxane and 1,3-bis(2-aminoethylaminomethyl)tetramethyldisiloxane, and further preferably 1,3-bis(aminopropyl)-1,1,3,3-tetramethyldisiloxane.

3. The formaldehyde-free particle board according to claim 1, wherein, The curing agent is selected from amine curing agents, preferably aliphatic amine catalysts, more preferably one or more of triethylamine, triethylenediamine, N,N-dimethylcyclohexylamine, N,N-dimethylhexadecylamine, and diethylenetriamine, and further preferably N,N-dimethylcyclohexylamine.

4. The formaldehyde-free particle board according to claim 1, characterized in that, The functionality of the isocyanate is 2.6 - 2.7; and / or The -NCO value of the isocyanate is 25 - 35 wt%; and / or The isocyanate includes polymethylene polyphenylisocyanate, preferably Wanhua Chemical CW20, 9132FC, 9131FC.

5. The aldehyde-free particleboard according to claim 1, wherein The wood particle material includes poplar, eucalyptus, fir, or miscellaneous wood; and / or The size of the wood particles is (0.8 - 12) mm * (0.8 - 1.2) mm * (0.1 - 0.6) mm. Preferably, the raw materials of the upper surface layer and the lower surface layer use fine wood particles, and the raw materials of the core layer use coarse wood particles.

6. The formaldehyde-free particleboard according to any one of claims 1-5, characterized in that, The raw materials of the upper surface layer and the lower surface layer include by weight: The raw materials of the core layer include by weight:

7. The formaldehyde-free particleboard according to claim 6, wherein, The mass ratio of the upper surface layer, the core layer, and the lower surface layer is 1:(2.5 - 4):1, preferably 1:(3 - 3.5):

1.

8. A method for preparing the formaldehyde-free particleboard according to any one of claims 1-7, characterized in that, It includes the following steps: S1: Dry the wood particles and sort the fine wood particles and the coarse wood particles. S2: Apply the adhesive to the fine wood particles, and then add the reinforcing agent and water to obtain the preliminary materials for the upper surface layer and the lower surface layer respectively. S3: Apply the adhesive and the curing agent to the coarse wood particles, and then add water to obtain the preliminary material for the core layer. S4: Lay the preliminary material for the lower surface layer, the preliminary material for the core layer, and the preliminary material for the upper surface layer in sequence, and hot press to obtain the formaldehyde-free particleboard.

9. The preparation method according to claim 8, wherein In step S1, the wood particles are dried to a moisture content ≤ 2 wt%; and / or In step S4, for the hot press, the temperature is 180 - 250 °C, the pressure is 0.5 - 6 MpaG, and the time is 80 - 140 s.

10. Application of the formaldehyde-free particleboard according to any one of claims 1 - 7 or the formaldehyde-free particleboard prepared by the method according to claim 8 or 9 in the field of furniture boards.

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