Fireproof composite adhesive for plant fiber multilayer composite board

Abstract

The invention discloses a fireproof composite adhesive for a plant fiber multilayer composite board, which is prepared from the following components in percentage by mass: 30%-37% of magnesium oxide, 25%-29% of magnesium sulfate, 3%-8% of boric acid, 0.5%-1.5% of auxiliaries and 30%-43% of water. According to the adhesive disclosed by the invention, by optimizing the content of each component, excellent fireproof performance, moisture-proof performance and adhesion performance are realized, and the performance and the application range of the plant fiber multilayer composite board are remarkably improved. In addition, the adhesive disclosed by the invention is made of non-toxic and harmless environment-friendly materials, meets the requirement of modern society on environmental protection, and has no adverse effect on the environment and human health.

Description

Technical Field

[0001] The present invention relates to a fireproof adhesive, and particularly to a fireproof composite adhesive for plant fiber multi-layer composite boards. Background Art

[0002] With the increasing requirements for environmental protection and fire safety, plant fiber multi-layer composite boards are increasingly widely used in the fields of construction, furniture, etc. However, the adhesives used in traditional plant fiber multi-layer composite boards often have problems such as insufficient fireproof performance, poor moisture-proof performance, and insufficient bonding strength, which limit their application in some specific occasions. In addition, some adhesives also contain harmful substances, posing potential threats to the environment and human health. Therefore, developing an environmentally friendly adhesive with excellent fireproof performance, moisture-proof performance, and bonding performance is of great significance for improving the performance and application scope of plant fiber multi-layer composite boards. Summary of the Invention

[0003] The object of the present invention is to provide a fireproof composite adhesive for plant fiber multi-layer composite boards.

[0004] To achieve the above object, the present invention is implemented according to the following technical solution:

[0005] The fireproof composite adhesive for plant fiber multi-layer composite boards of the present invention is made of magnesium oxide, magnesium sulfate, boric acid, an auxiliary agent, and water. By mass ratio, it contains 30%-37% of the magnesium oxide, 25%-29% of the magnesium sulfate, 3%-8% of the boric acid, 0.5%-1.5% of the auxiliary agent, and 30%-43% of the water.

[0006] Preferably, the auxiliary agent is one or more of silicon dioxide, titanium dioxide, and rutile. Based on a total amount of 1000 g of the adhesive, the content of the magnesium oxide is 320 g, the content of the magnesium sulfate is 260 g, the content of the boric acid is 50 g, the content of the auxiliary agent is 1 g, and the content of the water is 369 g.

[0007] Preferably, the auxiliary agent is silicon dioxide. Based on a total amount of 1000 g of the adhesive, the content of the silicon dioxide is 1 g.

[0008] A method for preparing a multi-layer composite board of plant fibers uses the fireproof composite adhesive for the multi-layer composite board of plant fibers to bond the layers of the multi-layer composite board of plant fibers together. Specifically, the fireproof composite adhesive for the multi-layer composite board of plant fibers is coated between the multi-layer plant fiber layers, and then the plant fiber layers coated with the fireproof composite adhesive for the multi-layer composite board of plant fibers are pressed into a board through a hot pressing process. And the oxygen index of the multi-layer composite board of plant fibers is not less than 40%. The thickness of the multi-layer composite board of plant fibers is 5-20 mm. The multi-layer composite board of plant fibers is used in the fields of construction, furniture or decoration.

[0009] The beneficial effects of the present invention are:

[0010] The present invention is a fireproof composite adhesive for a multi-layer composite board of plant fibers. Compared with the prior art, the present invention realizes excellent fireproof performance, moisture-proof performance and bonding performance by reasonably proportioning components such as magnesium oxide, magnesium sulfate, boric acid, additives and water. Specifically, the adhesive of the present invention has the following technical effects:

[0011] Fireproof performance: By optimizing the contents of magnesium oxide, magnesium sulfate and boric acid, the oxygen index of the multi-layer composite board of plant fibers is significantly increased, making it reach or exceed 40%, meeting the high-standard fireproof requirements.

[0012] Moisture-proof performance: The adhesive of the present invention can still maintain good bonding performance in a high-humidity environment, effectively preventing the occurrence of delamination of the board, and ensuring the stability and durability of the board.

[0013] Bonding performance: By precisely controlling the contents of each component, the adhesive of the present invention can provide excellent bonding strength under different conditions, ensuring the firm and reliable interlayer bonding of the multi-layer composite board of plant fibers.

[0014] Environmental protection performance: The adhesive of the present invention uses non-toxic and harmless environmental protection materials, meets the requirements of environmental protection in modern society, and has no adverse effects on the environment and human health. Description of the drawings

[0015] Figure 1 is a bar chart of the oxygen index of multi-layer composite boards prepared with ordinary fireproof composite adhesives with different magnesium oxide contents;

[0016] Figure 2 is a bar chart of the oxygen index of multi-layer composite boards prepared with ordinary fireproof composite adhesives with different magnesium sulfate contents;

[0017] Figure 3 is a bar chart of the oxygen index of multi-layer composite boards prepared with ordinary fireproof composite adhesives with different boric acid contents;

[0018] Figure 4 It is a column chart of the oxygen index of multi-layer composite boards prepared with enhanced fireproof composite adhesives with different silica contents. Specific implementation manners

[0019] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. The illustrative embodiments and explanations of this invention are used to explain the present invention, but do not limit the present invention.

[0020] The fireproof composite adhesive for plant fiber multi-layer composite boards of the present invention is made of magnesium oxide, magnesium sulfate, boric acid, an auxiliary agent and water. By mass ratio, it contains 30%-37% of the magnesium oxide, 25%-29% of the magnesium sulfate, 3%-8% of the boric acid, 0.5%-1.5% of the auxiliary agent, and 30%-43% of the water.

[0021] Preferably, the auxiliary agent is one or more of silica, titanium dioxide, and rutile. Based on a total amount of 1000 g of the adhesive, the content of the magnesium oxide is 320 g, the content of the magnesium sulfate is 260 g, the content of the boric acid is 50 g, the content of the auxiliary agent is 1 g, and the content of the water is 369 g.

[0022] Preferably, the auxiliary agent is silica. Based on a total amount of 1000 g of the adhesive, the content of the silica is 1 g.

[0023] A method for preparing plant fiber multi-layer composite boards according to the present invention uses the fireproof composite adhesive for plant fiber multi-layer composite boards to bond the layers of the plant fiber multi-layer composite boards together. Specifically, the fireproof composite adhesive for plant fiber multi-layer composite boards is coated between the multi-layer plant fiber layers, and then the plant fiber layers coated with the fireproof composite adhesive for plant fiber multi-layer composite boards are pressed into boards through a hot pressing process. And the oxygen index of the plant fiber multi-layer composite board is not less than 40%. The thickness of the plant fiber multi-layer composite board is 5-20 mm. The plant fiber multi-layer composite board is used in the fields of construction, furniture or decoration.

[0024] In order to study the effects of the contents of various components in the fireproof composite binder system on the combustion performance and bonding performance of the fireproof composite binder, first, a common fireproof composite binder was prepared with magnesium oxide, magnesium sulfate, boric acid and additives, and the effects of different content ratios of magnesium oxide, magnesium sulfate and boric acid on the combustion performance, moisture-proof and bonding performance of the common fireproof composite binder were studied; then, silica was added to the common fireproof composite binder to prepare a strengthened fireproof composite binder, and the effects of the content of silica on the combustion performance, moisture-proof and bonding performance of the strengthened fireproof composite binder were studied. The fireproof composite binders with different ratios were applied to the specimens of plant fiber multi-layer composite boards, and through the testing and analysis of the combustion performance, moisture-proof and bonding performance of the plant fiber multi-layer composite board specimens, the ratio of the fireproof composite binder system was further optimized.

[0025] Effect of Magnesium Oxide on the Oxygen Index and Bonding Performance of Common Fireproof Composite Binder

[0026] In order to study the effects of the content of magnesium oxide (MO, magnesium oxide) on the combustion performance and bonding performance of the common fireproof composite binder (NFCA, normal fireproof composite adhesive), first, common fireproof composite binders with different magnesium oxide contents were prepared: NFCA-MO1 to NFCA-MO4, and the formula is shown in Table 1; then, specimens of plant fiber multi-layer composite boards were prepared with this common fireproof composite binder, and their oxygen index, moisture-proof and bonding performance were tested.

[0027] Table 1 Formula Table of Common Fireproof Composite Binder with Different Magnesium Oxide Contents

[0028] Specimen Number Total Amount of Binder (g) Magnesium Oxide (g) NFCA-MO1 1000 300 NFCA-MO2 1000 320 NFCA-MO3 1000 350 NFCA-MO4 1000 370

[0029] Table 1 shows the formula table of common fireproof composite binders with different magnesium oxide contents. As shown in the table, 4 specimens of common fireproof composite binders with different magnesium oxide contents were prepared, and the sample numbers were NFCA-MO1 to NFCA-MO4. The total amount of each common fireproof composite binder specimen was 1000 g, and the content of magnesium oxide gradually increased from 300 g to 370 g. Specimens of plant fiber multi-layer composite boards were prepared with these 4 common fireproof composite binders with different magnesium oxide contents respectively.

[0030] Figure 1The oxygen index of plant fiber multi-layer composite boards prepared with ordinary fireproof composite adhesives with different magnesium oxide contents is shown. It can be seen from the figure that the change in the magnesium oxide content in the ordinary fireproof composite adhesive has an obvious impact on the oxygen index of the plant fiber multi-layer composite board. As the magnesium oxide content increases, the oxygen index of the plant fiber multi-layer composite board shows a trend of first increasing and then decreasing. When the magnesium oxide content is 300 g, the oxygen index of the plant fiber multi-layer composite board sample NFCA-MO1 is 35%; when the magnesium oxide content is 320 g, the oxygen index of the plant fiber multi-layer composite board sample NFCA-MO2 reaches the maximum value of 40%; when the magnesium oxide content increases to 370 g, the oxygen index of the plant fiber multi-layer composite board sample NFCA-MO4 decreases to 33%. Thus, it can be seen that when the magnesium oxide content in the ordinary fireproof composite adhesive system is 400 g, the oxygen index of the plant fiber multi-layer composite board sample is the highest. When the magnesium oxide content is too high, the combustion performance will be significantly reduced.

[0031] Table 2 Moisture-proof and bonding performance data of multi-layer composite boards prepared with ordinary fireproof composite adhesives with different magnesium oxide contents

[0032] Specimen Number Moisture-proof and Adhesion Performance NFCA-MO1 0 specimens delaminated NFCA-MO2 0 specimens delaminated NFCA-MO3 3 specimens delaminated NFCA-MO4 6 specimens delaminated

[0033] Table 2 shows the moisture-proof and bonding performance data of plant fiber multi-layer composite boards prepared with ordinary fireproof composite adhesives with different magnesium oxide contents. In the tests of moisture-proof and bonding performance, 6 plant fiber multi-layer composite board test samples were prepared for each ordinary fireproof composite adhesive formula. It can be seen from the table that the change in the magnesium oxide content in the ordinary fireproof composite adhesive has an obvious impact on the moisture-proof and bonding performance of the plant fiber multi-layer composite board. As the magnesium oxide content increases, the phenomenon of delamination of the plant fiber multi-layer composite board samples gradually increases, indicating that the moisture-proof and bonding performance of the ordinary fireproof composite adhesive gradually decreases. When the magnesium oxide content is 300 g and 320 g, none of the 6 samples of the plant fiber multi-layer composite board samples NFCA-MO1 and NFCA-MO2 showed delamination; when the magnesium oxide content is 350 g, 3 out of 6 samples of the plant fiber multi-layer composite board sample NFCA-MO3 showed delamination; when the magnesium oxide content increases to 370 g, all 6 samples of the plant fiber multi-layer composite board sample NFCA-MO4 showed delamination. Thus, it can be seen that when the magnesium oxide content in the ordinary fireproof composite adhesive system reaches 370 g, it will significantly reduce the moisture-proof and bonding performance of the ordinary fireproof composite adhesive, and then lead to the phenomenon of delamination of the plant fiber multi-layer composite board samples.

[0034] Analysis of the test data on oxygen index, moisture resistance and adhesion performance shows that when the content of magnesium oxide in the ordinary fireproof composite binder system is 320 g, the ordinary fireproof composite binder has good flame retardancy, moisture resistance and adhesion performance.

[0035] Effect of Magnesium Sulfate on Oxygen Index and Adhesion Performance of Ordinary Fireproof Composite Binder

[0036] To study the effect of magnesium sulfate (MS) content on the combustion performance and adhesion performance of the ordinary fireproof composite adhesive (NFCA), ordinary fireproof composite adhesives with different magnesium sulfate contents were first prepared: NFCA-MS1 to NFCA-MS4, and the formula is shown in Table 3. Then, plant fiber multi-layer composite board specimens were prepared using this ordinary fireproof composite adhesive, and their oxygen index, moisture resistance and adhesion performance were tested.

[0037] Table 3 Formula Table of Ordinary Fireproof Composite Adhesive with Different Magnesium Sulfate Contents

[0038] Specimen Number Total Amount of Binder (g) Magnesium Sulfate (g) NFCA-MS1 1000 250 NFCA-MS2 1000 260 NFCA-MS3 1000 270 NFCA-MS4 1000 290

[0039] Table 3 shows the formula table of ordinary fireproof composite adhesives with different magnesium sulfate contents. As shown in the table, 4 specimens of ordinary fireproof composite adhesives with different magnesium sulfate contents were prepared, and the sample numbers were NFCA-MS1 to NFCA-MS4. The total amount of each ordinary fireproof composite adhesive specimen was 1000 g, and the content of magnesium sulfate gradually increased from 250 g to 290 g. Plant fiber multi-layer composite board specimens were prepared using these 4 ordinary fireproof composite adhesives with different magnesium sulfate contents respectively.

[0040] Figure 2The oxygen index of plant fiber multi-layer composite boards prepared with ordinary fireproof composite adhesives with different magnesium sulfate contents is shown. It can be seen from the figure that the change in the magnesium sulfate content in the ordinary fireproof composite adhesive has a certain impact on the oxygen index of the plant fiber multi-layer composite board. As the magnesium sulfate content increases, the oxygen index of the plant fiber multi-layer composite board samples generally fluctuates within the range of 38%-40%. When the magnesium sulfate content is 250 g, the oxygen index of the plant fiber multi-layer composite board sample NFCA-MS1 is 39%; when the magnesium sulfate content is 260 g, the oxygen index of the plant fiber multi-layer composite board sample NFCA-MS2 reaches the maximum value of 40%; when the magnesium sulfate content increases to 270 g, the oxygen index of the plant fiber multi-layer composite board sample NFCA-MS3 decreases to 38%; when the magnesium sulfate content increases to 290 g, the oxygen index of the plant fiber multi-layer composite board sample NFCA-MS4 is 39%. Thus, it can be seen that when the magnesium sulfate content in the ordinary fireproof composite adhesive system is 260 g, the oxygen index of the plant fiber multi-layer composite board sample is the highest. Table 4 Moisture-proof and bonding performance data of multi-layer composite boards prepared with ordinary fireproof composite adhesives with different magnesium sulfate contents

[0041] Specimen Number Moisture-proof and Adhesion Performance NFCA-MS1 1 specimen delaminated NFCA-MS2 0 specimens delaminated NFCA-MS3 4 specimens delaminated NFCA-MS4 6 specimens delaminated

[0042] Table 4 shows the moisture-proof and bonding performance data of plant fiber multi-layer composite boards prepared with ordinary fireproof composite adhesives with different magnesium sulfate contents. In the tests of moisture-proof and bonding performance, 6 plant fiber multi-layer composite board test samples were prepared for each ordinary fireproof composite adhesive formula. It can be seen from the table that the change in the magnesium sulfate content in the ordinary fireproof composite adhesive has an obvious impact on the moisture-proof and bonding performance of the plant fiber multi-layer composite board. As the magnesium sulfate content increases, the phenomenon of delamination of the plant fiber multi-layer composite board samples gradually increases, indicating that the moisture-proof and bonding performance of the ordinary fireproof composite adhesive gradually decreases. When the magnesium sulfate content is 250 g, 1 out of 6 samples of the plant fiber multi-layer composite board sample NFCA-MS2 showed the phenomenon of delamination; when the magnesium sulfate content is 260 g, none of the 6 samples of the plant fiber multi-layer composite board sample NFCA-MS1 showed the phenomenon of delamination; when the magnesium sulfate content is 270 g, 4 out of 6 samples of the plant fiber multi-layer composite board sample NFCA-MS3 showed the phenomenon of delamination; when the magnesium sulfate content increases to 290 g, all 6 samples of the plant fiber multi-layer composite board sample NFCA-MS4 showed the phenomenon of delamination. Thus, it can be seen that when the magnesium sulfate content in the ordinary fireproof composite adhesive system reaches 290 g, it will significantly reduce the moisture-proof and bonding performance of the ordinary fireproof composite adhesive, thereby causing the phenomenon of delamination of the plant fiber multi-layer composite board samples.

[0043] Based on the analysis of the test data of the comprehensive oxygen index, moisture resistance and adhesion performance, it can be seen that when the content of magnesium sulfate in the ordinary fireproof composite binder system is 260 g, the ordinary fireproof composite binder has good flame retardant performance, moisture resistance and adhesion performance.

[0044] Effect of Boric Acid on Oxygen Index and Adhesion Performance of Ordinary Fireproof Composite Binder

[0045] To study the effect of boric acid (BA, boric acid) content on the combustion performance and adhesion performance of ordinary fireproof composite binder (NFCA, normal fireproof composite adhesive), ordinary fireproof composite binders with different boric acid contents were first prepared: NFCA-BA1 to NFCA-BA4, and the formula is shown in Table 5; then plant fiber multi-layer composite board specimens were prepared using this ordinary fireproof composite binder, and their oxygen index, moisture resistance and adhesion performance were tested.

[0046] Table 5 Formulation Table of Ordinary Fireproof Composite Binder with Different Boric Acid Contents

[0047] Specimen Number Total Amount of Binder (g) Boric Acid (g) NFCA-BA1 1000 30 NFCA-BA2 1000 40 NFCA-BA3 1000 50 NFCA-BA4 1000 70

[0048] Table 5 shows the formulation table of ordinary fireproof composite binders with different boric acid contents. As shown in the table, 4 specimens of ordinary fireproof composite binders with different boric acid contents were prepared, and the sample numbers were NFCA-BA1 to NFCA-BA4. The total amount of each ordinary fireproof composite binder specimen was 1000 g, and the content of boric acid gradually increased from 30 g to 80 g. Plant fiber multi-layer composite board specimens were prepared using these 4 ordinary fireproof composite binders with different boric acid contents respectively.

[0049] Figure 3 Shown is the oxygen index of plant fiber multi-layer composite boards prepared with ordinary fireproof composite binders with different boric acid contents. It can be seen from the figure that the change of boric acid content in the ordinary fireproof composite binder has an obvious effect on the oxygen index of plant fiber multi-layer composite boards. As the boric acid content increases, the oxygen index of plant fiber multi-layer composite boards shows a gradually increasing trend. When the boric acid content is 30 g, the oxygen index of the plant fiber multi-layer composite board specimen NFCA-BA1 is 35%; when the boric acid content is 40 g, the oxygen index of the plant fiber multi-layer composite board specimen NFCA-BA2 increases to 38%; when the boric acid content is 50 g, the oxygen index of the plant fiber multi-layer composite board specimen NFCA-BA3 is 40%; when the boric acid content increases to 70 g, the oxygen index of the plant fiber multi-layer composite board specimen NFCA-BA4 reaches the maximum value of 41%. Thus, it can be seen that when the content of boric acid in the ordinary fireproof composite binder system is up to 70 g at most, the oxygen index of the plant fiber multi-layer composite board specimen is the highest.

[0050] Table 6 Moisture-proof and bonding performance data of multi-layer composite boards prepared with ordinary fireproof composite adhesives with different boric acid contents

[0051]

[0052]

[0053] Table 6 shows the moisture-proof and bonding performance data of plant fiber multi-layer composite boards prepared with ordinary fireproof composite adhesives with different boric acid contents. In the tests of moisture-proof and bonding performance, 6 test samples of plant fiber multi-layer composite boards were prepared for each ordinary fireproof composite adhesive formula. It can be seen from the table that the change in the boric acid content in the ordinary fireproof composite adhesive has an obvious impact on the moisture-proof and bonding performance of the plant fiber multi-layer composite boards. As the boric acid content increases, the phenomenon of delamination of the plant fiber multi-layer composite board samples gradually weakens first and then gradually increases. When the boric acid content is 30 g, delamination occurs in all 6 samples of the plant fiber multi-layer composite board sample NFCA-BA1; when the boric acid content is 40 g and 50 g, no delamination occurs in the 6 samples of the plant fiber multi-layer composite board samples NFCA-BA2 and NFCA-BA3; when the boric acid content increases to 70 g, delamination occurs again in the 6 samples of the plant fiber multi-layer composite board sample NFCA-BA4. Thus, it can be seen that when the boric acid content in the ordinary fireproof composite adhesive system is 30 - 50 g, the ordinary fireproof composite adhesive has better moisture-proof and bonding performance. Too high or too low boric acid content may cause delamination of the plant fiber multi-layer composite board samples.

[0054] Combined with the analysis of the test data of oxygen index, moisture-proof and bonding performance, it can be seen that when the boric acid content in the ordinary fireproof composite adhesive system is 50 g, the ordinary fireproof composite adhesive has better flame retardant performance as well as moisture-proof and bonding performance.

[0055] Effect of silica on oxygen index and bonding performance of enhanced fireproof composite adhesive

[0056] In order to study the effect of silica (S) content on the combustion performance and bonding performance of enhanced fireproof composite adhesive (EFCA), enhanced fireproof composite adhesives with different silica contents: EFCA-S1 to EFCA-S4 were first prepared, and the formula is shown in Table 7; then plant fiber multi-layer composite board samples were prepared with this enhanced fireproof composite adhesive, and their oxygen index, moisture-proof and bonding performance were tested.

[0057] Table 7 Formulation Table of Reinforced Fireproof Composite Binder with Different Silica Contents

[0058] Specimen Number Ordinary Fire-proof Composite Binder (g) Silicon Dioxide (g) EFCA-S1 1000 0.5 EFCA-S2 1000 0.7 EFCA-S3 1000 1.0 EFCA-S4 1000 1.2

[0059] Table 7 shows the formulation table of the reinforced fireproof composite binder with different silica contents. As shown in the table, 4 specimens of the reinforced fireproof composite binder with different silica contents were prepared, and the sample numbers were EFCA-MO1 to EFCA-MO4. The reinforced fireproof composite binder specimens contained 1000 g of the ordinary fireproof composite binder and 0.5 g - 1.2 g of silica. Specimens of plant fiber multi-layer composite boards were prepared using these 4 kinds of reinforced fireproof composite binders with different silica contents respectively.

[0060] Figure 4 Shown are the oxygen indices of the plant fiber multi-layer composite boards prepared with the reinforced fireproof composite binder with different silica contents. It can be seen from the figure that the change in the silica content in the reinforced fireproof composite binder has an obvious effect on the oxygen index of the plant fiber multi-layer composite boards. With the increase in the silica content, the oxygen index of the plant fiber multi-layer composite boards shows a trend of increasing first and then decreasing. When the silica content is 0.5 g, the oxygen index of the plant fiber multi-layer composite board specimen EFCA-S1 is 35%; when the silica content is 0.7 g, the oxygen index of the plant fiber multi-layer composite board specimen EFCA-S2 is 40%; when the silica content is 1.0 g, the oxygen index of the plant fiber multi-layer composite board specimen EFCA-S3 reaches the maximum value of 44%; when the silica content increases to 1.2 g, the oxygen index of the plant fiber multi-layer composite board specimen EFCA-S4 decreases to 42%. Thus, it can be seen that when the silica content in the reinforced fireproof composite binder system is 1.0 g, the oxygen index of the plant fiber multi-layer composite board specimen is the highest. When the silica content is too high, the combustion performance will decrease.

[0061] Table 8 Data Sheet of Moisture Resistance and Bonding Performance of Multi-Layer Composite Boards Prepared with Reinforced Fireproof Composite Binder with Different Silica Contents

[0062] Specimen Number Moisture-proof and Adhesion Performance EFCA-S1 6 specimens delaminated EFCA-S2 6 specimens delaminated EFCA-S3 0 specimens delaminated EFCA-S4 0 specimens delaminated

[0063] Table 8 shows the moisture-proof and bonding performance data of plant fiber multi-layer composite boards prepared with enhanced fire-proof composite adhesives with different silica contents. In the tests of moisture-proof and bonding performance, 6 test samples of plant fiber multi-layer composite boards were prepared for each enhanced fire-proof composite adhesive formulation. As can be seen from the table, the change in the silica content in the enhanced fire-proof composite adhesive has an obvious impact on the moisture-proof and bonding performance of the plant fiber multi-layer composite boards. As the silica content increases, the phenomenon of delamination of the plant fiber multi-layer composite board samples gradually decreases, indicating that the moisture-proof and bonding performance of the enhanced fire-proof composite adhesive gradually improves. When the silica content is 0.5 g and 0.7 g, delamination of the boards occurred in all 6 samples of the plant fiber multi-layer composite board samples EFCA-S1 and EFCA-S2; when the silica content is 1.0 g and 1.2 g, delamination of the boards did not occur in any of the 6 samples of the plant fiber multi-layer composite board samples EFCA-S3 and EFCA-S4. Thus, it can be seen that when the silica content in the enhanced fire-proof composite adhesive system reaches 1 g, it will significantly improve the moisture-proof and bonding performance of the enhanced fire-proof composite adhesive, thereby avoiding the phenomenon of delamination of the plant fiber multi-layer composite board samples.

[0064] Based on the analysis of the test data of the limiting oxygen index, moisture-proof and bonding performance, it can be seen that when the silica content in the enhanced fire-proof composite adhesive system is 1 g, the enhanced fire-proof composite adhesive has good flame retardancy as well as moisture-proof and bonding performance.

[0065] In summary, when the content of magnesium oxide is 320 g, the content of magnesium sulfate is 260 g, the content of boric acid is 50 g, and the content of water is 369 g, the ordinary fire-proof composite adhesive has the best combustion performance, moisture-proof and bonding performance; when 1 g of silica is added to the ordinary fire-proof composite adhesive, the enhanced fire-proof composite adhesive has the best combustion performance, moisture-proof and bonding performance.

[0066] The technical solution of the present invention is not limited to the limitations of the above specific embodiments. Any technical deformation made according to the technical solution of the present invention falls within the protection scope of the present invention.

Claims

1. A fireproof composite adhesive for plant fiber multilayer composite board, characterized in that: The fireproof composite adhesive for plant fiber multilayer composite board is made of magnesium oxide, magnesium sulfate, boric acid, additives and water, and contains 30%-37% of magnesium oxide, 25%-29% of magnesium sulfate, 3%-8% of boric acid, 0.5%-1.5% of additives and 30%-43% of water in terms of mass ratio.

2. The fireproof composite adhesive for plant fiber multilayer composite board according to claim 1, characterized in that: The auxiliary agent is one or more of silicon dioxide, titanium dioxide and rutile.

3. The fireproof composite adhesive for plant fiber multilayer composite board according to claim 1 or 2, characterized in that: Based on 1000g of the total amount of adhesive, the content of magnesium oxide is 320g, the content of magnesium sulfate is 260g, the content of boric acid is 50g, the content of the auxiliary agent is 1g, and the content of water is 369g.

4. The fireproof composite adhesive for plant fiber multilayer composite board according to claim 1 or 2, characterized in that: The auxiliary agent is silicon dioxide, and the content of the silicon dioxide is 1g based on 1000g of the total amount of the adhesive.

5. A method for preparing a plant fiber multilayer composite board, characterized in that: The layers of the plant fiber multilayer composite board are bonded together using the fireproof composite adhesive for the plant fiber multilayer composite board according to any one of claims 1 to 4.

6. The method for preparing a plant fiber multilayer composite board according to claim 5, characterized in that: The bonding process is: coating the fireproof composite adhesive for plant fiber multilayer composite board between multiple plant fiber layers, and then pressing the plant fiber layers coated with the fireproof composite adhesive for plant fiber multilayer composite board into boards through a hot pressing process.

7. A plant fiber multilayer composite board, characterized in that: The plant fiber multilayer composite board is formed by bonding the fireproof composite adhesive for plant fiber multilayer composite boards according to any one of claims 1 to 4, and the oxygen index of the plant fiber multilayer composite board is not less than 40%.

8. The plant fiber multilayer composite board according to claim 7, characterized in that: The thickness of the plant fiber multilayer composite board is 5-20 mm.

9. The plant fiber multilayer composite board according to claim 7 or 8, characterized in that: The plant fiber multilayer composite board is used in the fields of construction, furniture or decoration.

10. A process for preparing a fireproof composite board using the fireproof composite adhesive for plant fiber multilayer composite board according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1: Weigh magnesium oxide, magnesium sulfate, boric acid, additives and water in proportion; S2: uniformly mixing the above components to prepare a fire-resistant composite adhesive; S3: applying a fire-retardant composite adhesive between the multiple plant fiber layers; S4: pressing the plant fiber layer coated with the fire-retardant composite adhesive into a board through a hot pressing process; S5: Drying the pressed sheet.

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