Magnesian ecological glue for wood board as well as preparation method and application of magnesium ecological glue

Abstract

The invention belongs to the technical field of cementing materials, and provides a magnesium ecological glue for wood boards, which comprises the following components by mass: 40-50 parts of magnesium oxide powder, 45-55 parts of a magnesium sulfate heptahydrate solution, 3-5 parts of a thickening time control agent, 4-6 parts of silica fume, and 1-4 parts of a modifier. The magnesium oxide powder is composed of light calcined magnesium oxide and high-activity magnesium oxide, the specific surface area of magnesium oxide in the light calcined magnesium oxide powder is 10-20 m < 2 > / g, and the specific surface area of magnesium oxide in the high-activity magnesium oxide powder is 80-100 m < 2 > / g. According to the magnesium ecological glue for the wood board, the magnesium oxide powder prepared from low-grade magnesite is used as a main component, resource utilization of waste magnesite is achieved, and the magnesium ecological glue has excellent water resistance and bonding strength.

Description

Technical Field

[0001] This invention relates to the field of cementitious materials technology, and in particular to a magnesium-based eco-adhesive for wood-based panels, its preparation method, and its application. Background Technology

[0002] With increasing public awareness of environmental protection and health, the environmental performance of home building materials has received unprecedented attention. In the production of wood-based panels, urea-formaldehyde resin adhesives have long been widely used due to their excellent bonding properties and low cost. However, during curing and use, they continuously release harmful volatile organic compounds (VOCs) such as formaldehyde, seriously endangering human health and polluting the indoor environment. Finding environmentally friendly, non-toxic, and formaldehyde-free adhesive alternatives has become an urgent need and an important issue for the industry.

[0003] On the other hand, while my country possesses abundant magnesite resources, the mining and processing processes generate a large amount of low-grade ore (typically referring to ore with low MgO content or high impurities). This low-grade ore, due to its low economic value, is often discarded and stockpiled, not only wasting valuable magnesium resources but also occupying land and potentially causing environmental problems such as dust and leachate pollution. How to efficiently and effectively utilize low-grade magnesite ore is of great significance for resource conservation and environmental protection. Meanwhile, the high and uncontrollable activity of lightly calcined magnesia produced by new kilns such as suspension kilns results in significant differences in its physicochemical properties compared to products from traditional reverberatory kilns. Downstream magnesium building material companies' existing stable production formulas and processes are incompatible, preventing the effective utilization of large quantities of high-quality, highly active magnesia. Traditional reverberatory kilns will gradually be replaced by new kilns such as suspension kilns. This industrial upgrading policy, while promoting energy conservation and emission reduction, also presents challenges to the production process of lightly calcined magnesia. Therefore, developing new technologies and products that can adapt to and efficiently utilize highly active magnesia has become a core issue urgently needing to be addressed in the downstream sectors of the magnesite industry.

[0004] Magnesium oxysulfate (MgO-MgSO4-H2O) cementitious materials have the advantages of wide availability of raw materials, low production energy consumption, low alkalinity of the cured body, excellent fire resistance, and no formaldehyde or other volatile organic compounds. Research has found that this system shows promise in utilizing magnesium oxide powder prepared from low-grade magnesite and has the potential to replace traditional wood-based panel adhesives. However, the current water resistance, bond strength, and interfacial compatibility with wood-based panels of magnesium oxysulfate cementitious materials do not meet the performance requirements of adhesives used in wood-based panels and require further improvement. Summary of the Invention

[0005] Therefore, the purpose of this invention is to provide a magnesium-based eco-adhesive for wood-based panels, its preparation method, and its application. The magnesium-based eco-adhesive for wood-based panels provided by this invention uses magnesium oxide powder prepared from low-grade magnesite ore as its main component, realizing the resource utilization of waste magnesite ore, and exhibiting excellent water resistance and bonding strength.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] This invention provides a magnesium-based eco-adhesive for wood-based panels, comprising the following components by weight:

[0008] 40-50 parts magnesium oxide powder, 45-55 parts magnesium sulfate heptahydrate solution, 3-5 parts setting regulator, 4-6 parts silica fume, and 1-4 parts modifier;

[0009] The magnesium oxide powder is composed of lightly calcined magnesium oxide powder and highly active magnesium oxide powder, wherein the specific surface area of ​​magnesium oxide in the lightly calcined magnesium oxide powder is 10~20m². 2 / g, the specific surface area of ​​magnesium oxide in the highly active magnesium oxide powder is 80~100m². 2 / g.

[0010] Preferably, the mass ratio of the lightly calcined magnesium oxide powder to the highly active magnesium oxide powder is 1:1.5 to 1:2.

[0011] Preferably, the active magnesium oxide content in the lightly calcined magnesium oxide powder is 60%~70%.

[0012] Preferably, the high-activity magnesium oxide powder contains 70% to 80% active magnesium oxide, and the high-activity magnesium oxide is prepared by calcination in a suspension kiln.

[0013] Preferably, the Baume degree of the magnesium sulfate heptahydrate solution is 29°Bé.

[0014] Preferably, the setting regulator is citric acid and boric acid.

[0015] Preferably, the modifier is sodium alginate.

[0016] This invention also provides a method for using magnesium-based eco-adhesive for wood-based panels, comprising the following steps:

[0017] A composite solution is obtained by mixing the setting regulator with magnesium sulfate heptahydrate solution;

[0018] Magnesium oxide powder is added to a composite solution and stirred to obtain a slurry;

[0019] The modifier is pre-dissolved into a gel and then added to the slurry to obtain magnesium-based eco-adhesive for wood-based panels.

[0020] Preferably, the stirring includes a first stirring and a second stirring, wherein the first stirring speed is 200~300 r / min and the first stirring time is 1~5 min; the second stirring speed is 600~800 r / min and the second stirring time is 1~5 min.

[0021] This invention also provides the application of magnesium-based eco-adhesive or magnesium-based eco-adhesive prepared by the above method in wood-based engineered wood products, wherein the wood-based engineered wood products include any one of plywood, MDF, particleboard, and blockboard.

[0022] Beneficial effects:

[0023] 1. The magnesium oxide powder component of the magnesium ecological adhesive provided by this invention is mainly made of low-grade magnesite ore, which greatly improves the utilization rate of waste ore, realizes the efficient utilization of low-grade magnesite ore, reduces the production cost of magnesium ecological adhesive, and conforms to the current concept of circular economy and green development.

[0024] 2. The magnesium-based eco-adhesive provided by this invention consists entirely of inorganic components, and its production and use do not easily generate formaldehyde or other harmful VOCs. Formaldehyde release was not detected (<0.005 mg / m³) when tested using the standard climate chamber method (GB / T 17657-2013). 3 This is far superior to the most stringent E0 grade (≤0.050 mg / m³). 3 (and formaldehyde-free engineered wood products standards requirements).

[0025] 3. The magnesium-based eco-adhesive provided by this invention has excellent fire resistance when used in wood-based panels, with a fire rating of A1. It is made from magnesium oxide, which has excellent high-temperature resistance. It is not easily combustible in high-temperature environments and can form a stable fireproof protective layer. When exposed to open flames or high temperatures, the magnesium-based eco-adhesive will not release toxic or harmful gases and can effectively inhibit the spread of flames.

[0026] 4. The magnesium-based eco-adhesive provided by this invention has excellent impregnation peeling performance and water resistance. When repeatedly impregnated in boiling water, there is no peeling or delamination between the adhesive layers, which meets the Class I impregnation peeling test standard in GB / T 17657-2013, 4.19.

[0027] 5. The preparation method of magnesium-based ecological adhesive provided by the present invention is relatively simple and easy to operate. It does not require harsh conditions such as high temperature and high pressure, which facilitates the application of adhesive, assembly and pre-pressing operations in the artificial board production line.

[0028] 6. The eco-friendly adhesive provided by this invention is suitable for bonding various wood-based panels, including plywood, medium / high density fiberboard, particleboard, and blockboard, providing an effective technical path for achieving full "formaldehyde-free" transformation of the wood-based panel industry. Attached Figure Description

[0029] Figure 1 This is a SEM image of lightly calcined magnesium oxide in a specific embodiment of the present invention;

[0030] Figure 2 This is a SEM image of highly active magnesium oxide in a specific embodiment of the present invention. Detailed Implementation

[0031] This invention provides a magnesium-based eco-adhesive for wood-based panels, comprising the following components by weight:

[0032] 40-50 parts magnesium oxide powder, 45-55 parts magnesium sulfate heptahydrate solution, 3-5 parts setting regulator, 4-6 parts silica fume, and 1-4 parts modifier.

[0033] In this invention, the magnesium-based eco-adhesive for wood-based panels comprises 40-50 parts by weight, preferably 45 parts; in this invention, the magnesium oxide powder is composed of light-burned magnesium oxide powder and highly active magnesium oxide powder, and the mass ratio of the light-burned magnesium oxide powder to the highly active magnesium oxide powder is preferably 1:1.5-1:2, more preferably 1:1.6-1:1.9 or 1:1.7-1:1.8.

[0034] In this invention, the active magnesium oxide content in the lightly calcined magnesium oxide powder is 60%~70%; the specific surface area of ​​magnesium oxide in the lightly calcined magnesium oxide powder is 10~20 m². 2 / g; In this invention, the composition of the lightly calcined magnesia is as follows: 60%~70% MgO, 4%~5% SiO2, 1%~2% CaO, 0.15%~0.3% Fe2O3, LOI≤10%. The lightly calcined magnesia is prepared from low-grade magnesite ore. This invention does not have special requirements for the preparation method, and conventional lightly calcined magnesia preparation processes in the art can be used.

[0035] The microstructure of lightly calcined magnesium oxide in this invention is as follows: Figure 1 As shown, the surface of the active magnesium oxide in the lightly calcined magnesium oxide powder is rough, with obvious boundaries, and the active reaction rate is slow.

[0036] In this invention, the active magnesium oxide content in the highly active magnesium oxide powder is 70%~80%; the specific surface area of ​​magnesium oxide in the highly active magnesium oxide powder is 80~100m². 2 / g; In this invention, the composition of the highly active magnesium oxide powder is as follows: 70%~80% MgO, 5%~10% SiO2, 3%~5% CaO, 0.7%~1.0% Fe2O3, LOI≤5%.

[0037] In this invention, the highly active magnesium oxide powder is preferably prepared by calcining low-grade magnesite ore in a suspension kiln, comprising the following steps: crushing the low-grade magnesite ore raw material to a size of 80-300 mm and transporting it to a suspension kiln, calcining the ore raw material using water gas generated by a gas generator as fuel; the calcination temperature is 800-1000℃, and the calcination time is 4-6 h; the low-grade magnesite ore in the suspension kiln begins to decompose at a temperature of 800-1000℃ and undergoes a chemical reaction in the furnace to form granular highly active magnesium oxide powder.

[0038] The microstructure of the highly active magnesium oxide powder prepared by this invention is as follows: Figure 2 As shown, the active magnesium oxide in the high-activity magnesium oxide powder has smooth, stepped sides with no obvious boundaries, and exhibits high reactivity.

[0039] The present invention selects magnesium oxide powder composed of light-burned magnesium oxide powder and highly active magnesium oxide powder because highly active magnesium oxide alone has a large specific surface area, many lattice defects, and high surface energy. It reacts with magnesium sulfate at an extremely fast rate, and the 5·1·7 phase can be formed quickly, but the crystallization is insufficient. The resulting adhesive layer structure is loose, and the internal stress concentration caused by rapid expansion makes it prone to cracking after cooling, resulting in insufficient bonding strength. On the other hand, light-burned magnesium oxide alone has a relatively small specific surface area and reacts with magnesium sulfate relatively slowly, which cannot meet the requirements of industrial cold pressing.

[0040] This invention uses a mixture of lightly calcined magnesium oxide powder and highly active magnesium oxide powder, adjusting their mass ratio to 1:1.5~1:2, to precisely control the curing time of the eco-adhesive within 30-60 minutes. The rapid reaction of highly active magnesium oxide allows the adhesive layer to quickly form a preliminary bond during the pressing process, preventing the board from shifting. The slow reaction of lightly calcined magnesium oxide provides sufficient time for the hydration products to grow, ensuring that the adhesive layer's bonding strength continues to increase after the pressure is released.

[0041] Meanwhile, the 5-1-7 phase initially formed by the highly active magnesium oxide in the magnesium-based eco-adhesive of this invention consists of fine needle-like crystals, forming a "skeleton prototype." The subsequent 5-1-7 phase formed by the lightly calcined magnesium oxide consists of coarser rod-like crystals, filling the gaps between the needle-like crystals to form a dense "needle-rod interwoven" structure. This enhances the bonding strength and weather and water resistance of the eco-adhesive to the wood board, preventing the adhesive layer from cracking. At the same time, the rapid reaction of the highly active magnesium oxide can form an "early rigid layer" on the surface of the wood board adhesive layer, restraining the expansion caused by the slow reaction of the lightly calcined magnesium oxide and preventing the adhesive layer from peeling off from the wood due to the difference in expansion.

[0042] The 5-1-7 phase generated from lightly calcined magnesium oxide in the magnesium-based eco-adhesive of this invention has high crystallinity and lower hygroscopicity than highly active magnesium oxide products. It is closer to the hygroscopic characteristics of wood-based panels, which can reduce the deformation difference between the two when humidity changes.

[0043] In this invention, the magnesium-based eco-adhesive for wood-based panels comprises 45-55 parts by weight of magnesium sulfate heptahydrate solution, more preferably 50 parts; and preferably, the Baume degree of the magnesium sulfate heptahydrate solution is 29°Bé. In this invention, the Baume degree directly affects the supersaturation of the magnesium sulfate heptahydrate solution, thereby affecting the rate of magnesium oxide hydration and crystallization. A magnesium sulfate heptahydrate with a Baume degree of 29°Bé can synergistically control the setting rate of the eco-adhesive with the setting regulator, allowing the adhesive sufficient time to penetrate into the pores of the wood, forming a mechanical interlock, thereby achieving a more uniform bonding strength.

[0044] In this invention, the magnesium-based ecological adhesive for wood-based panels comprises 3-5 parts by weight of a setting regulator, preferably one or more of tartaric acid, oxalic acid, acetic acid, citric acid, and boric acid; in a specific embodiment of this invention, citric acid and boric acid are further preferred, with a mass ratio of citric acid to boric acid of 2-3:1-2; this invention selects citric acid and boric acid as setting regulators, which can synergistically improve the viscosity of the magnesium oxysulfate cementitious material slurry with the modifier, thereby improving the interfacial compatibility and bonding strength between the magnesium-based ecological adhesive and the wood-based panel. The specific principle is as follows:

[0045] 1) Citric acid and boric acid can lower the pH of the solution and inhibit the formation of Mg(OH)2; while sodium alginate can complex Mg. 2+ Reduce free Mg in solution 2+ The concentration is adjusted to achieve a stronger retarding effect.

[0046] 2) Citric acid, as a setting regulator and modifier, and sodium alginate can jointly promote the formation of the high-strength 5・1・7 phase and increase the proportion of the 5・1・7 phase in the hydration products.

[0047] 3) The setting regulator citric acid and the modifier sodium alginate can work together to improve the microstructure of magnesium oxysulfate, forming a denser and more uniform hardened body.

[0048] In this invention, the magnesium-based eco-adhesive for wood-based panels comprises 4 to 6 parts silica fume, more preferably 5 parts, by weight.

[0049] In this invention, the magnesium-based ecological adhesive for wood-based panels comprises 1-5 parts by weight of a modifier, more preferably 2-4 parts; the modifier is preferably any one of hydroxypropyl methylcellulose, sodium carboxymethyl cellulose, acrylate, and sodium alginate; in a specific embodiment of this invention, sodium alginate is preferred. The modifier of this invention is mainly used in magnesium-based cementitious materials to improve their brittleness, increase toughness, enhance interfacial bonding with the filler adhesive, and further improve water resistance.

[0050] This invention also provides a method for preparing magnesium-based eco-adhesive for wood-based panels, comprising the following steps:

[0051] A composite solution is obtained by mixing the setting regulator with magnesium sulfate heptahydrate solution;

[0052] Magnesium oxide powder is added to a composite solution and stirred to obtain a slurry;

[0053] The modifier is pre-dissolved into a gel and then added to the slurry to obtain magnesium-based eco-adhesive for wood-based panels.

[0054] This invention mixes a coagulating agent with magnesium sulfate heptahydrate solution to obtain a composite solution;

[0055] In this invention, the preferred mixing sequence is to add the coagulating agent to the magnesium sulfate heptahydrate solution. There are no special requirements for the mixing method and mixing time; the mixture can be stirred until it is completely dissolved to form a composite solution.

[0056] This invention involves adding magnesium oxide powder to a composite solution and stirring to obtain a slurry;

[0057] In this invention, it is preferable to mix lightly calcined magnesium oxide and highly active magnesium oxide to form magnesium oxide powder, and then add the composite solution and stir.

[0058] In this invention, the stirring includes a first stirring and a second stirring. The first stirring has a rotation speed of 200-300 r / min and a stirring time of 1-5 min. The second stirring has a rotation speed of 600-800 r / min and a stirring time of 1-5 min.

[0059] After obtaining the slurry, the present invention will pre-dissolve the modifier into a gel and add it to the slurry to obtain magnesium-based ecological adhesive for wood-based panels.

[0060] In this invention, the pre-dissolution is carried out in warm water, and the pre-dissolution temperature is preferably 50~60℃; the mass fraction of the gel is preferably 2%~3%. The pre-dissolution of the modifier in this invention is to ensure that the modifier is uniformly dispersed in the slurry.

[0061] This invention also provides an application of magnesium-based eco-adhesive for wood-based panels in wood-based engineered wood products, including any one of plywood, MDF, particleboard, and blockboard. The magnesium-based eco-adhesive provided by this invention is completely formaldehyde-free, possesses excellent bonding strength and water resistance, and can meet the production requirements of wood-based engineered wood products such as plywood, MDF, particleboard, or blockboard.

[0062] The following detailed description, in conjunction with embodiments, of the magnesium-based eco-adhesive for wood-based panels and its preparation method provided by the present invention, should not be construed as limiting the scope of protection of the present invention.

[0063] Example 1

[0064] 48 parts of magnesium oxide powder (16 parts of lightly calcined magnesium oxide powder with 65% MgO content and 32 parts of high-activity magnesium oxide powder with 72% MgO content), 50 parts of magnesium sulfate heptahydrate solution (Baumé degree 29°Bé), 1 part of boric acid, 2 parts of citric acid, 6 parts of silica fume, and 4 parts of sodium alginate.

[0065] Preparation method:

[0066] Citric acid and boric acid are added to magnesium sulfate heptahydrate solution and stirred until completely dissolved to form a sulfuric acid-citric acid-boric acid composite solution;

[0067] Add magnesium oxide powder to the composite solution, stir at a low speed of 300 r / min for 2 min, and then stir at a high speed of 800 r / min for 3 min to form a uniform slurry;

[0068] Sodium alginate was pre-dissolved in 50°C warm water to form a 3% (w / w) gel. This gel was then added to the slurry and stirred at 500 rpm for 5 minutes to ensure that the sodium alginate was evenly dispersed in the slurry, thus obtaining magnesium-based eco-adhesive.

[0069] Example 2

[0070] 48 parts of magnesium oxide powder (16 parts of lightly calcined magnesium oxide powder with 62% MgO content and 32 parts of high-activity magnesium oxide powder with 72% MgO content), 50 parts of magnesium sulfate heptahydrate solution (Baumé degree 29°Bé), 1 part of boric acid, 2 parts of citric acid, 5 parts of silica fume, and 3 parts of sodium alginate.

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

[0072] Example 3

[0073] 50 parts magnesium oxide powder (20 parts lightly calcined magnesium oxide powder with 62% MgO content, and 30 parts high-activity magnesium oxide powder with 78% MgO content), 55 parts magnesium sulfate heptahydrate solution (Baumé degree 29°Bé), 2 parts boric acid, 3 parts citric acid, 5 parts silica fume, and 3 parts sodium alginate.

[0074] The preparation method is the same as in Example 1.

[0075] Example 4

[0076] 50 parts magnesium oxide powder (20 parts lightly calcined magnesium oxide powder with 62% MgO content and 30 parts high-activity magnesium oxide powder with 80% content), 55 parts magnesium sulfate heptahydrate solution (Baumé degree 29°Bé), 2 parts boric acid, 3 parts citric acid, 4 parts silica fume, and 2.5 parts sodium alginate.

[0077] The preparation method is the same as in Example 1.

[0078] Comparative Example 1

[0079] 48 parts magnesium oxide powder (lightly calcined magnesium oxide powder with only 65% ​​MgO content), 50 parts magnesium sulfate heptahydrate solution (Baumé degree 29°Bé), 1 part boric acid, 2 parts citric acid, 6 parts silica fume, and 4 parts sodium alginate.

[0080] Compared with Example 1, the difference is that no highly active magnesium oxide powder was added, but the preparation method is the same as in Example 1.

[0081] Comparative Example 2

[0082] 50 parts magnesium oxide powder (high-activity magnesium oxide powder with only 80% MgO content), 55 parts magnesium sulfate heptahydrate solution (Baumé degree 29°Bé), 2 parts boric acid, 3 parts citric acid, 4 parts silica fume, and 2.5 parts sodium alginate.

[0083] Compared with Example 4, the difference is that lightly calcined magnesium oxide powder was not added, and the preparation method is the same as in Example 1.

[0084] Comparative Example 3

[0085] Commercially available urea-formaldehyde resin was purchased as a control group and its performance was tested.

[0086] Comparative Example 4

[0087] Commercially available E1 grade urea-formaldehyde resin was purchased as a control group and its performance was tested.

[0088] Comparative Example 5

[0089] Commercially available modified low-formaldehyde adhesives were purchased as a control group and their performance was tested.

[0090] The magnesium-based ecological adhesive prepared in Examples 1-4 and Comparative Examples 1-2 was evenly applied to poplar wood blanks. After the veneers were orthogonally spliced, they were placed on a cold press and pressed for 30 minutes to set the shape. The cold-pressed and shaped boards were then placed in a hot press and hot-pressed at 110-130℃ for 30 minutes to obtain a seven-layer wood plywood (size 1.22m*2.44m). The performance indicators of the wood plywood prepared with commercially available urea-formaldehyde adhesive in Comparative Examples 3-5 are compared in Table 1.

[0091] This product is not only suitable for wood plywood, but also for blockboard, particleboard and medium / high density fiberboard. This test only uses wood plywood as an example.

[0092] Comparative Example 1: Magnesium-based eco-adhesive prepared using lightly calcined magnesium oxide powder. Due to the long setting time, the board was not shaped after 30 minutes of room temperature cold pressing and was directly subjected to hot pressing.

[0093] Comparative Example 2 used magnesium-based eco-adhesive prepared with highly active magnesium oxide powder. Due to the excessively fast setting time, there was not enough time for operation. After the veneers were spliced ​​into a seven-layer wood plywood, the magnesium-based eco-adhesive was almost solidified. Therefore, it was not cold-pressed for shaping and was directly hot-pressed.

[0094] The performance testing method is as follows:

[0095] 1) Transverse static bending strength: according to 4.7 of GB / T 17657-2013.

[0096] 2) Surface bonding strength: As per 4.16 of GB / T 17657-2013.

[0097] 3) Impregnation peel performance: Conducted according to 4.19 (Class I impregnation peel test) in GB / T 17657-2013.

[0098] 4) Moisture content: as specified in section 4.3 of GB / T17657—2013.

[0099] 5) Formaldehyde emission determination: Performed according to the test method in GB 18580.

[0100] Table 1 Summary of performance test results for wood plywood

[0101] Transverse static bending strength (MPa) Surface bond strength (MPa) Impregnation and peeling performance Moisture content (%) Formaldehyde emission (mg / m³) Example 1 22 1.12 qualified 9.0 Not detected Example 2 22 1.14 qualified 9.0 Not detected Example 3 24 1.16 qualified 8.8 Not detected Example 4 24 1.16 qualified 8.9 Not detected Comparative Example 1 21 1.10 qualified 9.1 Not detected Comparative Example 2 22 1.09 qualified 9.0 Not detected Comparative Example 3 18 0.96 Unqualified 9.5 0.124 Comparative Example 4 18.5 1.05 Unqualified 9.3 0.114 Comparative Example 5 19.2 1.09 Unqualified 9.2 0.109

[0102] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A magnesium-based eco-adhesive for wood-based panels, comprising the following components by weight: 40-50 parts magnesium oxide powder, 45-55 parts magnesium sulfate heptahydrate solution, 3-5 parts setting regulator, 4-6 parts silica fume, and 1-4 parts modifier; The magnesium oxide powder is composed of lightly calcined magnesium oxide powder and highly active magnesium oxide powder, wherein the specific surface area of ​​magnesium oxide in the lightly calcined magnesium oxide powder is 10~20m². 2 / g, the specific surface area of ​​magnesium oxide in the highly active magnesium oxide powder is 80~100m². 2 / g.

2. The magnesium-based eco-adhesive for wood-based panels according to claim 1, characterized in that, The mass ratio of the lightly calcined magnesium oxide powder to the highly active magnesium oxide powder is 1:1.5 to 1:

2.

3. The magnesium-based eco-adhesive for wood-based panels according to claim 1, characterized in that, The active magnesium oxide content in the lightly calcined magnesium oxide powder is 60%~70%.

4. The magnesium-based eco-adhesive for wood-based panels according to claim 1, characterized in that, The high-activity magnesium oxide powder contains 70% to 80% active magnesium oxide and is prepared by calcination in a suspension kiln.

5. The magnesium-based eco-adhesive for wood-based panels according to claim 1, characterized in that, The Baume degree of the magnesium sulfate heptahydrate solution is 29°Bé.

6. The magnesium-based eco-adhesive for wood-based panels according to claim 1, characterized in that, The setting regulator is citric acid and boric acid.

7. The magnesium-based eco-adhesive for wood-based panels according to claim 1, characterized in that, The modifier is sodium alginate.

8. A method for preparing the magnesium-based eco-adhesive for wood-based panels according to any one of claims 1 to 7, comprising the following steps: A composite solution is obtained by mixing the setting regulator with magnesium sulfate heptahydrate solution; Magnesium oxide powder is added to a composite solution and stirred to obtain a slurry; The modifier is pre-dissolved into a gel and then added to the slurry to obtain magnesium-based eco-adhesive for wood-based panels.

9. The method according to claim 8, characterized in that, The stirring includes a first stirring and a second stirring, wherein the first stirring speed is 200~300 r / min and the first stirring time is 1~5 min; the second stirring speed is 600~800 r / min and the second stirring time is 1~5 min.

10. The application of the magnesium-based eco-adhesive according to any one of claims 1 to 7 or the magnesium-based eco-adhesive prepared by the method according to any one of claims 8 to 9 in wood-based engineered wood products, wherein the wood-based engineered wood products include any one of plywood, MDF, particleboard and blockboard.

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