Preparation method of low-density and high-strength foam adhesive and its application in lightweight particleboard

Abstract

The invention discloses a method for preparing a low-density high-strength foam adhesive and its application in a lightweight particleboard, comprising: mixing polyether polyol, triethanolamine, and polyether-modified silicone, stirring to obtain a polyether polyol solution; adding n-hexane to the polyether polyol solution at room temperature, stirring to obtain a foam adhesive prepolymer solution; adding diphenylmethane diisocyanate to the foam adhesive prepolymer solution at room temperature, stirring, and polymerizing and cross-linking to obtain a low-density high-strength foam adhesive. The invention obtains a polyurethane foam adhesive by generating a carbamate bond between the isocyanate in diphenylmethane diisocyanate and the hydroxyl of the polyether polyol under the action of a chain extension cross-linking agent; the foam adhesive utilizes its foaming performance to increase the contact area with the wood shavings, and then forms a large number of non-covalent bonds with the wood shavings through the carbamate bonds, and obtains a high adhesive strength when bonded to the wood.

Description

Technical Field

[0001] The invention belongs to the technical field of wood adhesives, and in particular relates to a preparation method of a low-density and high-strength foaming adhesive and application of the same in lightweight particleboards. Background Art

[0002] Particleboard is a board made of small-diameter wood, branches and other agricultural and forestry residues as raw materials, which is prepared by gluing and hot pressing. It has the advantages of low cost, stable structure, good processing performance, high resource utilization rate, and low processing energy consumption. It is widely used in the field of furniture manufacturing. Among them, lightweight and high-strength particleboard has become an important development direction of particleboard products due to its light weight, high strength, and excellent anti-deformation performance.

[0003] Lightweight and high-strength particleboard is made by applying foam adhesive, using the foam properties of the foam adhesive to fill the gaps between the particles, and at the same time increasing the contact area between the adhesive and the particles, thereby achieving a simultaneous improvement in the particleboard's light weight and high strength. The performance of the foam adhesive is a key factor in determining the mechanical properties of lightweight and high-strength particleboard. Currently, the foam adhesives used for lightweight particleboards mainly include isocyanate adhesives, polyurethane adhesives, aldehyde resin adhesives, and biomass adhesives.

[0004] At present, the foam adhesive for preparing lightweight particleboard is still in the laboratory research stage, and there are two major defects: on the one hand, the bonding effect between the adhesive layer and the particleboard is damaged due to the large amount of gas generated during the foaming process, resulting in a decrease in the internal bonding strength of the particleboard, affecting the surface finishing effect; on the other hand, the foam adhesive has poor uniformity in pore diameter and density due to the mismatch between the curing speed and the foam growth speed, which leads to a weakening of the strength of the foam adhesive layer of the foam adhesive, thereby affecting the performance of the particleboard. Summary of the invention

[0005] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0006] In view of the above problems and / or the problems existing in the prior art, the present invention is proposed.

[0007] Therefore, the object of the present invention is to overcome the deficiencies in the prior art and provide a method for preparing a low-density and high-strength foam adhesive.

[0008] In order to solve the above technical problems, the present invention provides the following technical solutions: a method for preparing a low-density and high-strength foam adhesive, comprising:

[0009] Mixing polyether polyol, triethanolamine and polyether modified silicone, and stirring to obtain a polyether polyol solution;

[0010] At room temperature, adding n-hexane into the polyether polyol solution and stirring to obtain a foaming adhesive prepolymer solution;

[0011] At room temperature, diphenylmethane diisocyanate is added into a foam adhesive prepolymer solution and stirred, and low-density and high-strength foam adhesive is obtained by polymerization and cross-linking.

[0012] As a preferred embodiment of the preparation method of the present invention, the mass ratio of the polyether polyol to triethanolamine is 1:0.15-0.5.

[0013] As a preferred embodiment of the preparation method of the present invention, the mass ratio of the polyether polyol to the polyether modified silicone is 1:0.15-0.5.

[0014] As a preferred embodiment of the preparation method of the present invention, the mass ratio of the polyether polyol to n-hexane is 1:0.15-0.5.

[0015] As a preferred embodiment of the preparation method of the present invention, the mass ratio of the polyether polyol to diphenylmethane diisocyanate is 1:0.5-1.2.

[0016] As a preferred embodiment of the preparation method of the present invention, the polyether polyol has a hydroxyl value of 400-460, a functionality of 4, and a molecular weight of 540.

[0017] Another object of the present invention is to overcome the deficiencies in the prior art and provide a low-density high-strength foam adhesive, wherein the low-density high-strength foam adhesive has the following characteristics:

[0018] (1) The adhesive can be slowly foamed within 20 to 30 minutes in a temperature range of 20 to 40°C;

[0019] (2) In the temperature range of 60-80°C, the foaming time can be controlled to be rapid within 5 minutes;

[0020] (3) The foam density of the foam adhesive is 0.07g / cm 3 The foaming ratio is 12 and the compression strength is 2.96MPa.

[0021] Another object of the present invention is to overcome the deficiencies in the prior art and provide a low-density, high-strength foamed adhesive for use in the preparation of lightweight particleboard.

[0022] As a preferred solution of the application of the present invention, it includes:

[0023] Apply the foam adhesive prepolymer solution to the coarse wood shavings by spraying, stirring and spraying, so that the adhesive and the coarse wood shavings are fully mixed to form a core layer of coarse wood shavings, and the amount of adhesive applied is 2-3.2%;

[0024] Applying soybean meal adhesive to fine wood shavings by spraying, stirring and spraying, so that the adhesive and fine wood shavings are fully mixed to form a surface layer of fine wood shavings, and the amount of adhesive applied is 6-8.2%;

[0025] The sandwich assembly method is adopted to assemble the surface layer, core layer and surface layer in sequence, and then pave and pre-press the surface layer in the mold;

[0026] After demoulding, three-stage hot pressing is carried out on a flat vulcanizing machine;

[0027] After cooling to room temperature, a lightweight and high-strength particleboard is obtained.

[0028] As a preferred solution of the application of the present invention, the parameters of the three-stage hot pressing are:

[0029] ①185℃, 3.8MPa, 5s;

[0030] ②185℃, 1.2MPa, 145s;

[0031] ③185℃, 2.0MPa, 30s.

[0032] Beneficial effects of the present invention:

[0033] (1) The present invention provides a method for preparing a low-density, high-strength foam adhesive, wherein the isocyanate group in diphenylmethane diisocyanate and the hydroxyl group of polyether polyol form a carbamate bond under the action of a chain extender and crosslinker to obtain a polyurethane foam adhesive; on the one hand, the foam adhesive uses its foaming performance to increase the contact area with wood shavings, and then forms a large number of non-covalent bonds with the wood shavings through the carbamate bonds; on the other hand, when the foam adhesive is bonded to the wood, part of the foam adhesive penetrates, diffuses, and polymerizes in situ on the surface of the wood to form a polyurethane topological bridge, thereby simultaneously forming a large number of hydrogen bonds with the adhesive layer and the wood shavings, generating strong binding energy, and thus obtaining a high adhesive relay.

[0034] (2) The present invention provides a method for adjusting the dosage of foaming agent and cross-linking agent to screen out the optimal dosage, thereby achieving simultaneous improvement of low density, high structural regularity and high compressive strength of the foamed adhesive.

[0035] (3) The present invention provides an application of a foaming adhesive in a lightweight particle board. By adjusting the foaming speed and foaming ratio of the foaming agent at different temperatures, a controllable foaming process is obtained, thereby achieving effective regulation of the foaming amount and foaming speed of the foaming adhesive in the particle board, thereby improving the mechanical strength of the particle board.

[0036] (4) The preparation process of the present invention is simple, the energy consumption is low, and it is easy to mass produce, which is conducive to industrial application and promotion. The development of new lightweight and high-strength particleboard is an important choice to reduce the consumption of wood resources, cope with the rising prices of raw materials, reduce transportation costs, and promote the technology of the wood-based panel industry from following to leading. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0038] Figure 1 The front view, top view and cross-sectional view of foaming with different amounts of diphenylmethane diisocyanate in the embodiments of the present invention are shown.

[0039] Figure 2 These are the front view, top view and cross-sectional view of foaming with different amounts of petroleum ether in the embodiments of the present invention.

[0040] Figure 3 This is a comparison chart of foaming of different foaming agents at different temperatures in an embodiment of the present invention.

[0041] Figure 4 The front view, cross-sectional view and cell structure under an optical microscope of different foaming agents at 80°C in the embodiments of the present invention are shown.

[0042] Figure 5 Comparison of the performance of particleboard made with foam adhesive and soybean meal adhesive.

[0043] Figure 6 The foamed adhesive prepared by adding different amounts of polyether-modified silicone is used to improve the internal bonding strength of particleboard. DETAILED DESCRIPTION

[0044] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0045] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0046] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0047] In the present invention, diphenylmethane diisocyanate: Wanhua Chemical Group Co., Ltd.; petroleum ether, n-hexane, n-pentane, triethanolamine: Aladdin reagent; polyether modified silicone (foam stabilizer): Jiangsu Meside Chemical Co., Ltd.; polyether polyol: Guangdong Qihua Chemical Co., Ltd.; purchased from Jiangsu Meside Chemical Co., Ltd.

[0048] Example 1

[0049] (1) Weigh 10 g of polyether polyol, 1 g of polyether-modified silicone, and 1 g of triethanolamine, and stir at room temperature for 5 min to obtain a polyether polyol solution.

[0050] (2) At room temperature, add 1 g of petroleum ether to the polyether polyol solution and stir for 2 min to obtain a foaming adhesive prepolymer solution.

[0051] (3) At room temperature, 13 g of the foam adhesive prepolymer solution was weighed, and 5 g, 12 g, and 15 g of diphenylmethane diisocyanate were added respectively. The mixture was stirred for 2 min and heated to 80° C. for a full reaction to obtain three types of foam adhesives.

[0052] (4) Test and calculate the density, expansion ratio and expansion time of the foaming resin;

[0053] The optimal dosage of diphenylmethane diisocyanate with low density, high foaming ratio and low foaming speed was screened out.

[0054] (5) Figure 1 The analysis shows that when the amount of diphenylmethane diisocyanate is 12g, the foam expansion ratio is the highest;

[0055] The top view shows that when the amount of diphenylmethane diisocyanate is 5 g, bubble collapse occurs;

[0056] When the amount of diphenylmethane diisocyanate was 15 g, the foaming did not form;

[0057] It can be seen from the cross-sectional view that when the amount of diphenylmethane diisocyanate is 5g or 15g, the foam cells are larger.

[0058] (6) According to the analysis in Table 1, when the amount of diphenylmethane diisocyanate is 12g, the foam density is the lowest (0.215gcm -3), the foaming ratio (volume after foaming divided by the volume of prepolymer) is the highest (12.23), and the foaming time is completed within 5 minutes (4.2 minutes). Therefore, 12g of diphenylmethane diisocyanate is the best dosage.

[0059] Table 1

[0060] Diphenylmethane diisocyanate (g) <![CDATA[Density (g / cm 3 )]]> Foaming ratio Reaction time (min) 5 0.215 4.167 3.2 12 0.056 12.23 4.2 15 0.325 3.326 2.9

[0061] Example 2

[0062] (1) Weigh 10 g of polyether polyol, 1 g of polyether-modified silicone, and 1 g of triethanolamine, and stir at room temperature for 5 min to obtain a polyether polyol solution.

[0063] (2) At room temperature, 0.5 g, 1 g, and 1.5 g of petroleum ether were added to the polyether polyol solution and stirred for 2 min to obtain three foaming adhesive prepolymer solutions.

[0064] (3) At room temperature, 13 g of each of the three foaming adhesive prepolymer solutions was weighed, and 12 g of diphenylmethane diisocyanate was added respectively. The mixture was stirred for 2 min and heated to 80° C. for full reaction to obtain the three foaming adhesives.

[0065] (4) Test and calculate the density, expansion ratio and foaming time of the foaming resin, and screen out the optimal foaming agent dosage with low density, high expansion ratio and low foaming speed.

[0066] (5) Figure 2 The analysis shows that when the amount of foaming agent is 1g, the foaming ratio is higher; the cross-sectional diagram shows that when the amount of foaming agent is 0.5g and 1.5g, the foam cells are larger.

[0067] (6) According to Table 2, when the amount of foaming agent is 1g, the foam density is the lowest (0.073gcm -3 ), the foaming ratio is as high as 12.15, and the foaming time is completed within 5 minutes (4.1 minutes).

[0068] Therefore, the optimal dosage is 1g of foaming agent.

[0069] Table 2

[0070] Foaming agent dosage (g) <![CDATA[Density (g / cm 3 )]]> Foaming ratio Reaction time (min) 0.5 0.084 10.16 4.3 1 0.073 12.15 4.1 1.5 0.143 3.621 4.2

[0071] Example 3

[0072] (1) Weigh 10 g of polyether polyol, 1 g of polyether-modified silicone, and 1 g of triethanolamine, and stir at room temperature for 5 min to obtain a polyether polyol solution.

[0073] (2) At room temperature, 1 g of petroleum ether, n-hexane, and n-pentane were added to 12 g of the polyether polyol solution and stirred for 2 min to obtain three foaming adhesive prepolymer solutions.

[0074] (3) At room temperature, 13 g of each of three foam adhesive prepolymers were weighed in four portions, and 12 g of diphenylmethane diisocyanate was added. The mixture was stirred for 2 min and heated at 20°C, 40°C, 60°C, and 80°C for a full reaction to obtain 12 types of foam adhesives.

[0075] (4) Test and calculate the density, expansion ratio, and foaming time of the foaming resin, and select the optimal amount of foaming agent with low density, high expansion ratio, and low foaming speed.

[0076] (5) In order to achieve effective control of the foaming speed and foaming performance, it is necessary to select a foaming agent that has a slow foaming speed or even no foaming at low temperatures and good foaming performance at high temperatures. This will enable the application of controllable foaming polyurethane adhesive as an adhesive in particleboard.

[0077] like Figure 3 As shown, at 20℃, 40℃ and 60℃, the foaming ratio of n-hexane is the lowest, and the foaming ratios of petroleum ether and n-pentane are both greater than 5.

[0078] (6) According to the data analysis in Table 3, at 20°C, 40°C, and 80°C, the foaming time of n-hexane is longer, while the foaming time of n-pentane is shorter.

[0079] Table 3

[0080]

[0081]

[0082] (7) Figure 4 As shown, at 80°C, the foam expansion ratios of the three foaming agents are similar, and the pore sizes are similar; the foam mechanical properties of n-hexane as the foaming agent are the best, with a compressive strength of 2.96 MPa.

[0083] (8) Referring to Table 4, selecting n-hexane as the foaming agent can achieve no foaming at room temperature and better foaming performance at high temperature.

[0084] At the same time, the controllable foaming of the foam adhesive is achieved, so that the foam adhesive can be fully mixed with the wood chips and laid at room temperature, and it is guaranteed that it can foam normally during the hot pressing process and its mechanical properties can be guaranteed, thereby meeting the light weight and high strength characteristics of the particleboard.

[0085] Table 4

[0086] Foaming agent <![CDATA[Density (g / cm 3 )]]> Foaming ratio Reaction time (min) n-Hexane 0.072 13 4.6 Petroleum ether 0.071 12 5.2 n-Pentane 0.062 11 4.1

[0087] Example 5

[0088] Foam adhesive for particleboard gluing performance:

[0089] (1) Weigh 10 g of polyether polyol, 1 g of polyether-modified silicone, and 1 g of triethanolamine, and stir at room temperature for 5 min to obtain a polyether polyol prepolymer solution.

[0090] (2) At room temperature, 1 g of n-hexane was added to the polyether polyol prepolymer solution and stirred for 2 minutes to obtain a foaming adhesive prepolymer.

[0091] (3) Weigh 13 g of the foam adhesive prepolymer, add 12 g of diphenylmethane diisocyanate, and continue stirring for 2 min to obtain a lightweight and high-strength foam adhesive.

[0092] (4) The foam adhesive prepolymer solution prepared above is applied to the core layer coarse wood chips, and the soybean meal adhesive is applied to the surface layer fine wood chips, and a sandwich "surface layer-core layer-surface layer" assembly method is adopted, wherein the mass ratio of the surface layer-core layer-surface layer is 1:3:1; paving → pre-pressing → hot pressing are performed to obtain a lightweight and high-strength particleboard.

[0093] Among them, the specific pressing process of particleboard:

[0094] Apply the foam adhesive prepolymer solution to the coarse wood shavings by spraying, stirring and spraying, so that the adhesive and the coarse wood shavings are fully mixed to form a core layer of coarse wood shavings, and the amount of adhesive applied is 3.2%;

[0095] The soybean meal adhesive is applied to the fine wood shavings by spraying, and the adhesive and the fine wood shavings are fully mixed while being stirred to form a surface layer of fine wood shavings, and the amount of adhesive applied is 8.2%;

[0096] The sandwich assembly method is adopted to assemble the surface layer, core layer and surface layer in sequence, and then pave and pre-press the surface layer in the mold;

[0097] After demoulding, three-stage hot pressing is performed on a flat vulcanizer (①185℃, 3.8MPa, 5s; ②185℃, 1.2MPa, 145s; ③185℃, 2.0MPa, 30s);

[0098] Cool to room temperature to obtain a lightweight and high-strength particleboard with a controlled density of 450kg / m 3 .

[0099] Comparative Example 2

[0100] Gluing properties of soybean meal adhesive for particleboard:

[0101] The soybean meal adhesive prepolymer solution is applied to the core layer coarse wood chips and the surface layer fine wood chips, and a sandwich "surface layer-core layer-surface layer" assembly method is adopted to carry out paving → pre-pressing → hot pressing to obtain ordinary particleboard.

[0102] Among them, the specific pressing process of particleboard:

[0103] The soybean meal adhesive prepolymer solution is sprayed on the coarse wood shavings, and the adhesive and the coarse wood shavings are fully mixed while being stirred to form a core layer of coarse wood shavings, and the amount of adhesive applied is 3.2%;

[0104] The soybean meal adhesive (same as CN201911185862.5) was applied to the fine wood by spraying, and the adhesive and the fine wood were fully mixed while stirring to form a surface layer of fine wood. The amount of adhesive applied was 8.2%;

[0105] The sandwich assembly method is adopted to assemble the surface layer, core layer and surface layer in sequence, and then pave and pre-press the surface layer in the mold; the mass ratio of surface layer-core layer-surface layer is 1:3:1;

[0106] After demoulding, three-stage hot pressing is carried out on a flat vulcanizer (①185℃, 3.8MPa, 5s; ②185℃, 1.2MPa, 145s; ③185℃, 2.0MPa, 30s); cooled to room temperature, a lightweight and high-strength particleboard with a density of 450kg / m 3 .

[0107] As shown in Table 5, the performance of foam adhesive particleboard meets the national standards and is better than soybean meal adhesive particleboard. The test method refers to GBT17657-2013, and the test standard refers to the requirements of the national standard (P2 type in GB / T 4897-2015).

[0108] Table 5

[0109]

[0110]

[0111] Comparative Example 3

[0112] (1) Weigh 11 g, 10.5 g, 10 g, and 9.5 g of polyether polyol, 0 g, 0.5 g, 1 g, and 1.5 g of polyether-modified silicone, and 1 g of triethanolamine, and stir at room temperature for 5 min to obtain a polyether polyol solution.

[0113] (2) At room temperature, add 1 g of petroleum ether to the polyether polyol solution and stir for 2 min to obtain a foaming adhesive prepolymer solution.

[0114] (3) At room temperature, 13 g of the foaming adhesive prepolymer solution was weighed, 12 g of diphenylmethane diisocyanate was added, the mixture was stirred for 2 min, and heated to 80° C. for a complete reaction to obtain a foaming adhesive.

[0115] (4) The analysis shows that the foaming ratio of adding polyether-modified silicone is higher than that of not adding polyether-modified silicone. The foam produced without adding polyether-modified silicone has more bubbles due to uneven foaming.

[0116] (5) The foam adhesive prepolymer solution prepared above is applied to the core layer coarse wood chips, and the soybean meal adhesive is applied to the surface layer fine wood chips, and a sandwich "surface layer-core layer-surface layer" assembly method is adopted, wherein the mass ratio of the surface layer-core layer-surface layer is 1:3:1; paving → pre-pressing → hot pressing are performed to obtain a lightweight and high-strength particleboard.

[0117] Among them, the specific pressing process of particleboard:

[0118] Apply the foam adhesive prepolymer solution to the coarse wood shavings by spraying, stirring and spraying, so that the adhesive and the coarse wood shavings are fully mixed to form a core layer of coarse wood shavings, and the amount of adhesive applied is 3.2%;

[0119] The soybean meal adhesive is applied to the fine wood shavings by spraying, and the adhesive and the fine wood shavings are fully mixed while being stirred to form a surface layer of fine wood shavings, and the amount of adhesive applied is 8.2%;

[0120] The sandwich assembly method is adopted to assemble the surface layer, core layer and surface layer in sequence, and then pave and pre-press the surface layer in the mold;

[0121] After demoulding, three-stage hot pressing is performed on a flat vulcanizer (①185℃, 3.8MPa, 5s; ②185℃, 1.2MPa, 145s; ③185℃, 2.0MPa, 30s);

[0122] Cool to room temperature to obtain a lightweight and high-strength particleboard with a controlled density of 450kg / m 3

[0123] (6) By Figure 6 Analysis shows that the internal bonding strength of particleboards made with polyether-modified silicone meets national standards, and when the polyether-modified silicone is 1g, the internal bonding strength is the largest (0.74Mpa). This is because polyether-modified silicone makes the foaming adhesive foam more uniform and dense, thereby improving the mechanical strength of the board.

[0124] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the present invention.

Claims

1. A method for preparing a low-density and high-strength foam adhesive, characterized in that: include, Mixing polyether polyol, triethanolamine and polyether modified silicone, and stirring to obtain a polyether polyol solution, wherein the mass ratio of the polyether polyol to the triethanolamine is 1:0.1, and the mass ratio of the polyether polyol to the polyether modified silicone is 1:0.1; At room temperature, adding n-hexane to the polyether polyol solution and stirring to obtain a foaming adhesive prepolymer solution, wherein the mass ratio of the polyether polyol to the n-hexane is 1:0.1; At room temperature, diphenylmethane diisocyanate is added into a foam adhesive prepolymer solution and stirred to polymerize and cross-link to obtain a low-density and high-strength foam adhesive, wherein the mass ratio of polyether polyol to diphenylmethane diisocyanate is 1:1.

2.

2. The preparation method according to claim 1, characterized in that: The polyether polyol has a hydroxyl value of 400 to 460, a functionality of 4, and a molecular weight of 540.

3. The low-density and high-strength foamed adhesive prepared by the preparation method according to claim 1 or 2, characterized in that: The low-density and high-strength foam adhesive has the following characteristics: (1) The adhesive can be slowly foamed within a temperature range of 20 to 40°C, and the foaming time can be controlled to be within 20 to 30 minutes; (2) In the temperature range of 60~80℃, the foaming time can be controlled within 5 minutes for rapid foaming; (3) The foam density of the foaming adhesive at 80°C is 0.072 g / cm 3 The foaming ratio is 13 and the compression strength is 2.96MPa.

4. Use of the low-density, high-strength foamed adhesive according to claim 3 in the preparation of lightweight particleboard.

5. The use according to claim 4, characterized in that: include, Apply the foam adhesive prepolymer solution to the coarse wood shavings by spraying, stirring and spraying, so that the adhesive and the coarse wood shavings are fully mixed to form a core layer of coarse wood shavings, and the amount of glue applied is 2-3.2%; Apply the soybean meal adhesive to the fine wood shavings by spraying, stirring and spraying, so that the adhesive and the fine wood shavings are fully mixed to form a surface layer of fine wood shavings, and the amount of adhesive applied is 6-8.2%; The sandwich assembly method is adopted to assemble the surface layer, core layer and surface layer in sequence, and then pave and pre-press the surface layer in the mold; After demoulding, three-stage hot pressing is carried out on a flat vulcanizing machine; After cooling to room temperature, a lightweight and high-strength particleboard is obtained.

6. The use according to claim 5, characterized in that: The parameters of the three-stage hot pressing are: ①185℃, 3.8 MPa, 5 s; ②185℃, 1.2 MPa, 145 s; ③185℃, 2.0 MPa, 30 s.

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