Active formaldehyde-removing particleboard and its manufacturing process

Abstract

The invention discloses an active formaldehyde-removing particleboard and a manufacturing process thereof. A multilayer gradient particle sandwich structure is manufactured by a method in which particles are mixed with an adhesive and then hot-pressed, with a core layer formed by coarse particleboard, an attachment layer formed by fine particleboard, and an adsorption catalytic reaction surface layer formed by activated carbon particles loaded with a formaldehyde-removing catalyst. Gas channels are constructed inside and outside the board. When free formaldehyde released by the board is controlled and released into space through the gas channels, it is adsorbed and catalytically decomposed by the activated carbon particles loaded with the formaldehyde-removing catalyst, and then carbon dioxide and moisture are discharged through the gas channels, thereby achieving a formaldehyde-free effect for the board. At the same time, activated carbon particles loaded with the formaldehyde-removing catalyst are placed on the surface layer, which can actively adsorb the free formaldehyde released by the board and formaldehyde in the indoor air at the same time. The formaldehyde-removing catalyst decomposes the adsorbed formaldehyde, and the catalyst has the performance of long-term use.

Description

Technical Field

[0001] The invention belongs to the technical field of artificial boards, and particularly relates to an active formaldehyde-removing particleboard and a manufacturing process thereof. Background Art

[0002] The production of artificial boards requires adhesives, including phenolic adhesives, melamine adhesives, urea-formaldehyde adhesives, MDI adhesives, and soy adhesives. Formaldehyde-free adhesives like MDI and soy adhesives are used in a relatively small proportion of artificial boards due to insufficient production capacity and high costs. MDI adhesive, in particular, is much more expensive than other adhesives, resulting in a low usage rate and inability to meet current production demands. Urea-formaldehyde adhesives, on the other hand, account for over 85% of all adhesives used due to their low price, widespread availability of raw materials, and the ability to produce boards that meet performance requirements.

[0003] According to the "Formaldehyde Emission Classification of Artificial Boards and Their Products" (GB / T 39600-2021), when the requirements of E0, E1, and ENF are met for production and use, when the cumulative usage of low-formaldehyde boards per unit area does not exceed a certain value, the formaldehyde content is not likely to exceed the standard. When the usage exceeds a certain value, the formaldehyde emission is likely to exceed the standard. That is, according to the "Guidelines for Indoor Load Limits of Artificial Boards Based on Limit Formaldehyde Emissions" (GB / T39598-2021), 10m 2 The number of artificial boards that can be used in a room is shown in the following table:

[0004] Table 1 10m 2 The number of wood-based panels that can be used in a room

[0005]

[0006] Since most wood panels on the market aren't treated with formaldehyde-removing agents, the urea-formaldehyde, phenol-formaldehyde, and melamine-based glues used in wood-based panels continuously release free formaldehyde during production and use. When the cumulative concentration in a space exceeds the limit, it can cause lasting harm to the human body. Furthermore, there's currently no solution to eliminate this cumulative concentration within the panels themselves. Therefore, even low-formaldehyde panels are subject to usage limits, which, to a certain extent, restricts the use of wood-based panels in modern home decor. Summary of the Invention

[0007] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide an active formaldehyde-removing particleboard and its production process, which solves the problem of formaldehyde release from artificial boards in the above-mentioned background technology and also solves the problem of excessively high cumulative formaldehyde concentration in the space.

[0008] One of the technical solutions adopted by the present invention to solve the technical problem is: providing a production process for active formaldehyde removal particleboard, comprising the following steps:

[0009] 1) Cutting the wood raw material into chips and drying them, wherein the moisture content after drying is controlled to be 3-5 wt%;

[0010] 2) screening the dried flakes according to particle size to separate them into coarse flake particles with a length of 18 to 50 mm, a width of 4 to 12 mm, and a thickness of 0.5 to 0.8 mm and fine flake particles with a length of 2 to 13 mm, a width of 0.4 to 1.3 mm, and a thickness of 0.1 to 0.3 mm;

[0011] 3) applying an adhesive to the coarse wood shavings particles, the fine wood shavings particles, and the activated carbon particles loaded with the formaldehyde removal catalyst; the activated carbon particles have a size of 100 to 1500 μm;

[0012] 4) paving the sized coarse wood shavings, fine wood shavings, and activated carbon particles loaded with a aldehyde removal catalyst to form a slab with the coarse wood shavings as a core layer and the fine wood shavings and activated carbon particles loaded with a aldehyde removal catalyst sequentially laid on the surface of the core layer;

[0013] 5) Hot pressing the slab to form a particleboard at a temperature of 175-185°C, with a final thickness of 18 mm ± 0.5 mm, to obtain the active formaldehyde-removing particleboard. Excessively high hot pressing temperatures can cause the adhesive to melt excessively, preventing uniform interparticle spacing after flowing to the underlying substrate. Excessively low or high hot pressing thicknesses can also affect interparticle spacing, thereby hindering the formation of gas channels.

[0014] In a preferred embodiment of the present invention, the paving order in step 4) is: activated carbon particles, fine wood shavings particles, coarse wood shavings particles, fine wood shavings particles, and activated carbon particles from bottom to top.

[0015] In a preferred embodiment of the present invention, in step 4), 310-440 g / m 2 The coarse wood shavings are paved with a size of 18 to 50 mm in length, 4 to 12 mm in width, and 0.5 to 0.8 mm in thickness. 2 The paving is done with fine wood particles, the size of which is 2 to 13 mm long, 0.4 to 1.3 mm wide, and 0.1 to 0.3 mm thick; the paving is done with a weight of 25 to 50 g / m 2 Activated carbon particles loaded with a aldehyde removal catalyst are laid, wherein the particle size distribution of the activated carbon particles is 100 to 1500 μm.

[0016] In a preferred embodiment of the present invention, the wood raw material includes a mixture of one or more of poplar, eucalyptus, pine, and bamboo.

[0017] In a preferred embodiment of the present invention, the adhesive includes phenolic adhesive, melamine adhesive, or urea-formaldehyde adhesive.

[0018] In a preferred embodiment of the present invention, the formaldehyde removal catalyst is a manganese dioxide catalyst.

[0019] In a preferred embodiment of the present invention, the preparation method of activated carbon particles loaded with formaldehyde removal catalyst is as follows: activated carbon particles with a particle size distribution of 100 to 1500 μm are cleaned with deionized water to remove surface impurities, and dried at a constant temperature of 100 to 120°C for 2-3 hours to constant weight; 25-35 parts of activated carbon particles are placed in 65-75 parts of KMnO4 with a concentration of 0.4 mol / L and 60-70 parts of MnSO4 with a concentration of 0.5 mol / L in turn, H2SO4 is added dropwise to adjust the pH to 3 to 4, shaken on a shaker for 6-7 hours, immersed, rinsed, dried at 60-70°C, placed in a muffle furnace and calcined at 330-350°C for 4-6 hours, and cooled.

[0020] The second technical solution adopted by the present invention to solve its technical problem is: providing an active formaldehyde-removing particle board made by the above-mentioned process, which has a multi-layer gradient particle sandwich structure with a core layer formed by coarse wood particle particles, an attachment layer formed by fine wood particle particles, and an adsorption catalytic reaction surface layer formed by activated carbon particles loaded with formaldehyde-removing catalysts; a number of gas channels are left in the board, and the gas channels are distributed between the particles of each layer and connected to the outside of the board body.

[0021] In a preferred embodiment of the present invention, an interface layer is provided between the adhesion layer and the adsorption catalytic reaction surface layer, and between the core layer and the adhesion layer. The interface layer is formed by mixing two adjacent layers of particles with an adhesive.

[0022] In a preferred embodiment of the present invention, the gas channels distributed from the core layer to the adsorption catalytic reaction surface layer have a gradient decreasing channel size, and the gas channels located on the adsorption catalytic reaction surface layer serve as internal reaction product discharge channels and external space gas adsorption channels at the same time.

[0023] Compared with the background technology, this technical solution has the following advantages:

[0024] The present invention addresses the problems of high formaldehyde concentration in artificial boards and the drawbacks of formaldehyde removal in the current market. Without changing the glue used for the boards (using urea-formaldehyde glue or the like as the board glue), a multilayer gradient particle sandwich structure is produced by hot pressing after mixing particles with an adhesive, the structure comprising a core layer formed by coarse wood shavings, an attachment layer formed by fine wood shavings, and an adsorption catalytic reaction surface layer formed by activated carbon particles loaded with a formaldehyde removal catalyst. The structure and process parameters are used to control the hot pressing temperature, pressure conditions, and thickness of the finished product, thereby avoiding excessive tightness or looseness between the particles and rationally constructing gas channels inside and outside the board. First, the free formaldehyde released by the board is controlled. Second, the released formaldehyde will be adsorbed and catalytically decomposed by the activated carbon particles loaded with the formaldehyde removal catalyst when flowing to the external space through the gas channel. Similarly, carbon dioxide and moisture are discharged through the gas channel, thereby achieving a formaldehyde-free effect for the board. Third, the activated carbon particles loaded with the formaldehyde removal catalyst are placed on the surface layer, which can actively adsorb the free formaldehyde released by the board while adsorbing formaldehyde in the indoor air. The formaldehyde removal catalyst decomposes the adsorbed formaldehyde, and the catalyst has a long-term and efficient catalytic effect. The higher the room temperature, the higher the activity of the catalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic structural diagram of the active formaldehyde removal particleboard in Example 1;

[0026] Figure 2 Figure 2 is a diagram of the test device.

[0027] Among them, 1-core layer, 11-coarse wood shavings particles, 2-attachment layer, 21-fine wood shavings particles, 3-adsorption catalytic reaction surface layer, and 31-activated carbon particles loaded with formaldehyde removal catalyst. DETAILED DESCRIPTION

[0028] Example 1

[0029] A process for producing an active formaldehyde-removing particleboard comprises the following steps:

[0030] 1) Cutting the wood raw material into chips and drying them, wherein the moisture content after drying is controlled to be 3-5 wt%;

[0031] 2) Screening the dried flakes according to particle size to separate them into coarse wood shavings 11 with a length of 18 to 50 mm, a width of 4 to 12 mm, and a thickness of 0.5 to 0.8 mm, and fine wood shavings 21 with a length of 2 to 13 mm, a width of 0.4 to 1.3 mm, and a thickness of 0.1 to 0.3 mm;

[0032] Preparation of activated carbon particles 31 loaded with aldehyde removal catalyst:

[0033] Activated carbon with a particle size distribution of 100-1500 μm was cleaned with deionized water to remove surface impurities and then dried at a constant temperature of 100-120°C for 2-3 hours to constant weight. 25-35 parts of the treated activated carbon were placed in 65-75 parts of a 0.4 mol / L KMnO₄ solution and 60-70 parts of a 0.5 mol / L MnSO₄ solution, respectively. H₂SO₄ was added dropwise to adjust the pH to 3-4. The mixture was shaken on a shaker for 6-7 hours, followed by impregnation, rinsing, and drying at 60-70°C. The mixture was then calcined in a muffle furnace at 330-350°C for 4-6 hours and cooled to obtain activated carbon particles loaded with an activated manganese oxide catalyst. All raw materials are expressed in parts by weight. Finally, 31 parts of the activated carbon particles loaded with the aldehyde removal catalyst were passed through a 200-mesh sieve, and particles larger than 200 mesh were selected.

[0034] 3) applying an adhesive to the coarse wood shavings particles 11, the fine wood shavings particles 21, and the activated carbon particles 31 loaded with a formaldehyde removal catalyst, wherein the adhesive is urea-formaldehyde adhesive;

[0035] 4) The coarse wood shavings 11, fine wood shavings 21 and activated carbon particles 31 loaded with aldehyde removal catalyst are laid out after sizing to form a slab with the coarse wood shavings 11 as the core layer 1 and the fine wood shavings 21 and activated carbon particles 31 loaded with aldehyde removal catalyst laid out in sequence on the surface of the core layer 1; this embodiment adopts a five-layer sandwich structure, and the specific laying order is: first lay a layer of activated carbon particles 31 loaded with aldehyde removal catalyst on the bottom layer, then lay 21 layers of fine wood shavings, then lay 11 layers of coarse wood shavings, continue to lay 21 layers of fine wood shavings, and finally lay 31 layers of activated carbon particles loaded with aldehyde removal catalyst. Among them, the 31 layers of activated carbon particles loaded with aldehyde removal catalyst are at a density of 25 to 50 g / m 2 For paving, 21 layers of fine wood particles at 80-120g / m 2 Paving, 11 layers of coarse wood shavings at 310-440g / m 2 Paving.

[0036] 5) hot pressing the slab to form a particleboard at a hot pressing temperature of 175-185° C. and a thickness of 18 mm±0.5 mm after pressing, thereby obtaining an active formaldehyde-removing particleboard.

[0037] like Figure 1 The active formaldehyde-removing particleboard prepared in this embodiment has a five-layer gradient particle sandwich structure, which includes a core layer 1 formed by coarse wood particle particles 11, an attachment layer 2 formed by fine wood particle particles 21, and an adsorption catalytic reaction surface layer 3 formed by activated carbon particles 31 loaded with formaldehyde-removing catalysts; a number of gas channels are left in the board, which are distributed between the particles of each layer and connected to the outside of the board.

[0038] Among them, an interface layer is provided between the adhesion layer 2 and the adsorption catalytic reaction surface layer 3, and between the core layer 1 and the adhesion layer 2. The interface layer is formed by mixing two adjacent layers of particles and an adhesive.

[0039] The gas channels inside and outside the board constructed in this embodiment have a gradient-decreasing channel size distributed from the core layer 1 to the adsorption catalytic reaction surface layer 3, thereby achieving control of the free formaldehyde released by the board; in addition, the gas channels located in the adsorption catalytic reaction surface layer 3 serve as internal reaction product discharge channels and external space gas adsorption channels at the same time: ① When the released formaldehyde flows to the external space through the gas channel, it will be adsorbed and catalytically decomposed by the activated carbon particles 31 loaded with the formaldehyde removal catalyst, and the gas channel is also used to discharge carbon dioxide and moisture, thereby solving the problem of formaldehyde release; ② The activated carbon particles 31 loaded with the formaldehyde removal catalyst are placed in the adsorption catalytic reaction surface layer 3, which can actively adsorb the free formaldehyde released by the board while adsorbing formaldehyde in the indoor air. The formaldehyde removal catalyst decomposes the adsorbed formaldehyde, thereby solving the problem of high cumulative concentration in the space, and is not affected by temperature and light conditions.

[0040] Comparative Examples 1 to 5

[0041] The difference between Comparative Examples 1 to 4 and Example 1 is that the loading states of the activated carbon particles on the surface are respectively unloaded catalyst, chitosan, TiO2 photocatalyst, and tourmaline.

[0042] Comparative Example 1: The activated carbon without catalyst adsorbed formaldehyde no longer adsorbed formaldehyde after saturation, and released the adsorbed formaldehyde into the space as the temperature increased.

[0043] The chitosan of Comparative Example 2 has a high formaldehyde removal efficiency in the initial stage, but as the chitosan is consumed, the efficiency gradually decreases until it is completely ineffective. The formaldehyde removal effect lasts only a few days to a few months, which is not long-lasting and cannot meet the demand that the average service life of furniture exceeds 10 years.

[0044] The TiO2 photocatalyst of Comparative Example 3 can only remove formaldehyde under light conditions, and cannot remove formaldehyde at night or under light-shielding conditions;

[0045] The tourmaline in Comparative Example 4 removes formaldehyde by generating negative ions, but its efficiency is lower than that in Example 1, and if the concentration of the generated negative ions is too high, it will have side effects on the human body.

[0046] Comparative Example 5 is a commercially available sample of the same specifications without formaldehyde removal treatment.

[0047] Test method: In a sealed container of equal volume (such as Figure 2), set up the formaldehyde sensor, cut 20cm*20cm*1.8cm sample blocks*4 pieces, place them vertically in a container, initially drop formaldehyde solution into it, and let the formaldehyde diffuse in the container after volatilization. Regularly record the changes in the formaldehyde sensor value. Test conditions: room temperature 25℃, humidity 50%.

[0048] Table 2 Formaldehyde concentration test table

[0049]

[0050] From the above test results, it can be seen that the formaldehyde concentration of the samples without formaldehyde removal treatment gradually increased, reaching a maximum of 0.32 mg / m 3 In the formaldehyde test of the sample in Example 1, the formaldehyde concentration first increased and then gradually decreased. The initial formaldehyde concentration of Comparative Example 1 increased and then decreased. As the activated carbon adsorption was saturated, the formaldehyde concentration increased to a higher value. Chitosan in Comparative Example 2 had a certain effect on the decomposition of formaldehyde. As the chitosan was consumed, the formaldehyde concentration increased to a higher value. The photocatalyst in Comparative Example 3 had a general effect on the decomposition of formaldehyde, mainly because the catalyst was not completely on the surface and was mostly covered. Tourmaline in Comparative Example 4 had a certain effect on the decomposition of formaldehyde. The formaldehyde concentration of Comparative Example 5 continued to increase. In summary, it can be seen that the sample in Example 1 has the best effect on the decomposition of formaldehyde.

[0051] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A process for producing an active formaldehyde-removing particleboard, characterized by: The steps include: 1) Cutting the wood raw material into chips and drying them, wherein the moisture content after drying is controlled to be 3-5 wt%; 2) screening the dried flakes according to particle size to separate them into coarse flake particles with a length of 18 to 50 mm, a width of 4 to 12 mm, and a thickness of 0.5 to 0.8 mm and fine flake particles with a length of 2 to 13 mm, a width of 0.4 to 1.3 mm, and a thickness of 0.1 to 0.3 mm; 3) applying an adhesive to the coarse wood shavings, the fine wood shavings and the activated carbon particles loaded with the aldehyde removal catalyst; the size of the activated carbon particles loaded with the aldehyde removal catalyst is 100-1500 μm; the preparation method of the activated carbon particles loaded with the aldehyde removal catalyst is as follows: cleaning the activated carbon particles with a particle size distribution of 100-1500 μm with deionized water to remove surface impurities, and drying at a constant temperature of 100-120° C. for 2-3 hours to constant weight; placing 25-35 parts of the activated carbon particles in 65-75 parts of 0.4 mol / L KMnO4 and 60-70 parts of 0.5 mol / L MnSO4 solution in sequence by mass, adding H2SO4 dropwise to adjust the pH to 3-4, shaking on a shaker for 6-7 hours, impregnating, rinsing, drying at 60-70° C., placing in a muffle furnace at 330-350° C. for 4-6 hours, and cooling to obtain the product; 4) The sizing-applied coarse wood shavings, fine wood shavings and activated carbon particles loaded with formaldehyde removal catalyst are paved. forming a slab with coarse wood shavings as a core layer and fine wood shavings and activated carbon particles loaded with a formaldehyde removal catalyst sequentially laid on the surface of the core layer; 5) The slab is hot-pressed to form a particleboard at a hot-pressing temperature of 175-185° C., and the thickness after pressing is 18 mm ± 0.5 mm, thereby obtaining an active formaldehyde-removing particleboard, wherein a plurality of gas channels are left in the board, and the gas channels are distributed between the particles of each layer and connected to the outside of the board body, and the channel size has a gradient decreasing from the core layer to the surface layer.

2. The process for producing an active formaldehyde-removing particleboard according to claim 1, characterized in that: The paving order in step 4) is: from bottom to top, activated carbon particles loaded with formaldehyde removal catalyst, fine wood shavings particles, coarse wood shavings particles, fine wood shavings particles, and activated carbon particles loaded with formaldehyde removal catalyst.

3. The process for producing an active formaldehyde-removing particleboard according to claim 1, characterized in that: Step 4) with 310~440g / m 2 Pavement coarse wood shavings, 80 ~ 120g / m 2 Paving fine wood shavings, 25 ~ 50g / m 2 Activated carbon particles loaded with formaldehyde removal catalyst are laid.

4. The process for producing an active formaldehyde-removing particleboard according to claim 1, characterized in that: The wood raw material includes a mixture of one or more of poplar, eucalyptus, pine and bamboo.

5. The process for producing an active formaldehyde-removing particleboard according to claim 1, characterized in that: The adhesive includes phenolic adhesive, melamine adhesive and urea-formaldehyde adhesive.

6. The process for producing an active formaldehyde-removing particleboard according to claim 1, characterized in that: The aldehyde removal catalyst is a manganese dioxide catalyst.

7. An active formaldehyde-removing particleboard produced by the process according to any one of claims 1 to 6, characterized in that: It has a multi-layer gradient particle sandwich structure with a core layer formed by coarse wood shavings, an attachment layer formed by fine wood shavings, and an adsorption catalytic reaction surface layer formed by activated carbon particles loaded with formaldehyde removal catalyst; a number of gas channels are left in the plate, and the gas channels are distributed between the particles of each layer and connected to the outside of the plate body; the gas channels distributed from the core layer to the adsorption catalytic reaction surface layer have a gradient decreasing channel size, and the gas channels located on the adsorption catalytic reaction surface layer serve as internal reaction product discharge channels and external space gas adsorption channels at the same time.

8. The active formaldehyde-removing particleboard according to claim 7, characterized in that: An interface layer is provided between the adhesion layer and the adsorption catalytic reaction surface layer, and between the core layer and the adhesion layer. The interface layer is formed by mixing two adjacent layers of particles with an adhesive.

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