CN118496612B - Environment-friendly composite board and production process thereof - Google Patents

Abstract

The present invention belongs to the technical field of composite materials, and specifically relates to an environmentally friendly composite board and a production process thereof. The environmentally friendly composite board provided by the present invention is prepared from an adhesive, modified bamboo fiber, a polymer resin, a filler, isopropyl titanate triisostearate, polymethyl methacrylate and anhydrous ethanol. In the present invention, vinyl acetate, vinyl triethoxysilane and ethyl methacrylate are used as reaction monomers to obtain a polyvinyl acetate emulsion adhesive by emulsion polymerization, which effectively improves the bonding strength of the adhesive; the bamboo fiber is treated with an aqueous phosphoric acid solution under ultrasonic conditions, and then carboxyl groups are introduced into the surface of the bamboo fiber under the condition that potassium permanganate is used as an initiator, thereby improving the compatibility of the bamboo fiber with the polymer resin.

Description

Environmentally friendly composite board and its production process

Technical Field

The invention belongs to the technical field of composite materials, and in particular relates to an environmentally friendly composite board and a production process thereof.

Background Art

Composite panels are made of two or more materials with different properties combined by physical or chemical methods to form panels with new properties. With the advancement of science and technology and the increasing requirements of consumers for environmental protection and new energy, composite panels are developing towards intelligence and environmental protection.

Wood plastic board is a composite material made of low-value biomass fibers such as sawdust, wood chips, bamboo fiber, rice husk, wheat straw, soybean skin, peanut shell, bagasse, cotton straw and other low-value biomass fibers and plastic. It has the advantages of both plant fiber and plastic. It is an environmentally friendly, energy-saving and pollution-free material, which reduces the production cost of composite materials. Among them, bamboo fiber has the characteristics of good air permeability, instant water absorption, strong wear resistance and good dyeability, and is widely used in many fields such as flooring, furniture, cabinets, wall decoration materials, etc. However, the good water absorption of bamboo fiber will cause the board to deform, and the compatibility of bamboo fiber with polymer resin is poor, so bamboo fiber needs to be modified. For example, the Chinese patent document with publication number CN115368748A discloses a one-time forming veneer formaldehyde-free biomass composite board, in which eucalyptus sawdust is mixed with straw, crushed and sieved after drying, bamboo fiber is added, and sodium hydroxide aqueous solution is added for soaking, and the biomass base material is obtained after drying, and a coupling agent and anhydrous ethanol are sprayed on the filler to obtain a modified filler, and then the biomass base material is mixed with the modified filler and an adhesive, and pressed into a composite board. Although this modification method can improve the compatibility and wettability of bamboo fiber and polymer in the composite board, the high concentration of alkaline solution will damage the bamboo fiber and reduce the mechanical strength of the composite board.

In addition, as consumers' awareness of environmental protection and attention to health increase, people have extremely high requirements for the release of aldehyde gas in composite panels. In the production process of traditional composite panels, a large amount of adhesives containing aldehyde substances are used, which will release formaldehyde gas during use, endangering human health. Therefore, it is urgent to develop a new type of zero-aldehyde adhesive to replace aldehyde adhesives. The Chinese patent application document with publication number CN112300592A discloses a zero-formaldehyde high-strength cotton straw artificial board, including an artificial board body made of artificial board raw materials, the artificial board raw materials include cotton straw, polypropylene and polyurethane adhesives, cotton straw is organically combined with polypropylene and polyurethane adhesives as artificial board raw materials to make artificial boards, which have the advantages of zero formaldehyde and high strength, but the bonding strength of polyurethane adhesives is poor, resulting in low mechanical strength of artificial boards.

Summary of the invention

In order to solve the technical problems existing in the related art such as poor compatibility of bamboo fibers, low mechanical strength of composite boards, formaldehyde release from adhesives, etc., the purpose of the present invention is to provide an environmentally friendly composite board and a production process thereof.

In order to achieve the above object, the technical solution of the present invention is as follows:

An environmentally friendly composite board comprises the following components and their weight proportions:

30-40 parts of adhesive, 15-20 parts of modified bamboo fiber, 30-35 parts of polymer resin, 10-15 parts of filler, 3-5 parts of isopropyl titanate triisostearate, 3-5 parts of polymethyl methacrylate, 20-30 parts of anhydrous ethanol;

The preparation method of the adhesive is as follows: adding deionized water and an emulsifier into a three-necked flask, stirring, adding vinyl acetate and potassium persulfate, heating, respectively dropping vinyl triethoxysilane and ethyl methacrylate, controlling the dropping time within 0.6-1h, continuing to heat, reacting until no reflux liquid is generated, cooling, adding propylene glycol, γ-aminopropyl triethoxysilane and sodium bicarbonate solution, cooling to room temperature, and obtaining the adhesive.

The water resistance of polyvinyl acetate emulsion is poor, and the bonding strength of the board made of polyvinyl acetate emulsion adhesive will decrease under hot and humid conditions. In the present invention, vinyl acetate, vinyl triethoxysilane, and ethyl methacrylate are used as reaction monomers to obtain a polyvinyl acetate emulsion adhesive through emulsion polymerization; the addition of vinyl triethoxysilane can introduce organic silicon segments into the molecular structure of the adhesive, which can not only improve the water resistance of the adhesive film, but also improve the heat resistance of the adhesive film; the addition of ethyl methacrylate can increase the cohesion of the adhesive, and at the same time introduce polar carboxyl groups into the molecular structure of the adhesive to produce steric hindrance, thereby increasing the stability of the adhesive film. In addition, in the present invention, γ-aminopropyl triethoxysilane is added to the adhesive, and the three ethoxy groups in its molecular structure can react with the groups on the surface of the filler in the formula of the environmentally friendly composite board, and the amino group can undergo a cross-linking reaction with the groups in the polymer, effectively improving the bonding strength of the adhesive.

Furthermore, in the preparation method of the adhesive, the emulsifier is one of polyoxyethylene ether, polyvinyl alcohol, and polysorbate.

Furthermore, the dosage of each component in the preparation method of the adhesive is: 30-40 parts of deionized water, 8-12 parts of emulsifier, 20-25 parts of vinyl acetate, 5-8 parts of potassium persulfate, 10-14 parts of vinyl triethoxy silane, 5-10 parts of ethyl methacrylate, 6-8 parts of propylene glycol, 6-8 parts of γ-aminopropyl triethoxy silane, and 3-5 parts of sodium bicarbonate solution; the mass percentage of the sodium bicarbonate solution is 30-40%.

Furthermore, in the preparation method of the adhesive, the heating temperature is 70-75°C, the further heating temperature is 90-95°C, and the cooling temperature is 50-55°C.

Furthermore, the preparation method of the modified bamboo fiber is as follows: soak the bamboo fiber in an acetic acid aqueous solution, take it out and dry it; then add it to a phosphoric acid aqueous solution, ultrasonicate it, take it out and rinse it with clean water until it is neutral, so as to obtain pretreated bamboo fiber; mix the pretreated bamboo fiber with a potassium permanganate aqueous solution, heat it to 70-80°C, add acrylic acid dropwise under stirring, keep it warm for 1-1.5h after the addition is completed, filter it, and wash the bamboo fiber with an ethanol aqueous solution to obtain the pretreated bamboo fiber.

Bamboo fiber is mainly composed of three parts: cellulose, hemicellulose and lignin. Microfibers formed by hydrogen bonds of cellulose are intertwined and intertwined with each other. Lignin and hemicellulose are coated on the fiber surface as fillers of microfibers and adhesives between fibers. In the preparation method of the modified bamboo fiber of the present invention, during the ultrasonic process, the phosphoric acid aqueous solution can react with the hemicellulose and destroy the ether bonds in the lignin, so that the cellulose coated in the hemicellulose and lignin is exposed. Then, under the condition of potassium permanganate as an initiator, the hydroxyl group in the cellulose reacts with acrylic acid to introduce the carboxyl group into the surface of the bamboo fiber, thereby increasing the compatibility of the bamboo fiber with the polymer resin. In addition, since a large amount of hydroxyl groups are consumed in the bamboo fiber modification process, the water absorption of the modified bamboo fiber becomes poor, and the moisture and heat resistance of the obtained environmentally friendly composite board is improved.

Furthermore, in the preparation method of modified bamboo fiber, the pH value of the acetic acid aqueous solution is 5-5.5; the pH value of the phosphoric acid aqueous solution is 3-3.5, the ultrasonic frequency of the ultrasound is 35-40kHz, and the ultrasonic time is 20-30min.

Furthermore, in the preparation method of modified bamboo fiber, the mass percentage of potassium permanganate in the potassium permanganate aqueous solution is 0.5-1%; the dripping speed of acrylic acid is 0.2-1.5m ³ /h; the volume fraction of ethanol in the ethanol aqueous solution is 30%; and the mass ratio of the pretreated bamboo fiber, potassium permanganate and acrylic acid is 17-20:1-3:5-9.

Furthermore, the polymer resin is polyethylene, polypropylene, polystyrene or polyvinyl chloride.

Furthermore, the filler is one or more of calcium carbonate, calcium sulfate, silicon dioxide, calcium oxide, diatomaceous earth, and magnesium carbonate.

The present invention also provides a production process of the environmentally friendly composite board, comprising the following steps:

S1: isopropyl titanate triisostearate, polymethyl methacrylate and anhydrous ethanol are mixed, dispersed evenly, and then evenly sprayed on the filler to obtain a modified filler;

S2: Heat the polymer resin until it melts, add the modified bamboo fiber and the modified filler obtained in step S1 under stirring, cool down to 55-60° C. under stirring, add the adhesive, stir evenly, put into a mold, press into shape, and cool to obtain.

Compared with the prior art, the environmentally friendly composite board and its production process provided by the present invention have the following technical advantages:

(1) In the present invention, vinyl acetate, vinyl triethoxysilane and ethyl methacrylate are used as reaction monomers to obtain a polyvinyl acetate emulsion adhesive through emulsion polymerization, which effectively improves the bonding strength of the adhesive;

(2) The present invention uses a phosphoric acid aqueous solution to treat bamboo fibers under ultrasonic conditions, and then introduces carboxyl groups onto the surface of the bamboo fibers under the condition that potassium permanganate is used as an initiator, thereby improving the compatibility of the bamboo fibers with the polymer resin;

(3) The present invention adds isopropyl titanate triisostearate to the environmentally friendly composite board, which can couple the filler and the polymer resin. Polymethyl methacrylate is used as an interface modifier to increase the bonding strength between the polymer resin, the filler, and the modified bamboo fiber, thereby improving the mechanical properties of the environmentally friendly composite board.

DETAILED DESCRIPTION

The present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited to the following embodiments. Those skilled in the art can make various modifications based on the basic idea of the present invention, but as long as they do not deviate from the basic idea of the present invention, they are all within the scope of the present invention.

The preparation process of the environmentally friendly composite board in this specific embodiment includes the following steps:

S1: isopropyl titanate triisostearate, polymethyl methacrylate and anhydrous ethanol are mixed, dispersed evenly, and then evenly sprayed on the filler to obtain a modified filler;

S2: Heat the polymer resin until it melts, add the modified bamboo fiber and the modified filler obtained in step S1 under stirring, cool down to 55-60° C. under stirring, add the adhesive, stir evenly, put into a mold, press into shape, and cool to obtain.

Example 1

An environmentally friendly composite board comprises the following components and their weight proportions:

Adhesive 30g, modified bamboo fiber 15g, polypropylene 30g, silicon dioxide 10g, isopropyl titanate triisostearate 3g, polymethyl methacrylate 3g, anhydrous ethanol 30g;

The preparation method of the adhesive is as follows: 40g of deionized water and 8g of polyoxyethylene ether are added into a three-necked flask, stirred, 20g of vinyl acetate and 5g of potassium persulfate are added, the temperature is raised to 70°C, 10g of vinyl triethoxysilane and 5g of ethyl methacrylate are added dropwise respectively, the dropping time is controlled within 0.6h, the temperature is continued to be raised to 90°C, reacted until no reflux liquid is generated, cooled to 50°C, 6g of propylene glycol, 6g of γ-aminopropyl triethoxysilane and 3g of 30% by mass sodium bicarbonate solution are added, and cooled to room temperature to obtain the adhesive.

The preparation method of the modified bamboo fiber is as follows: soaking the bamboo fiber in an acetic acid aqueous solution with a pH value of 5, taking it out and drying it; then adding it into a phosphoric acid aqueous solution with a pH value of 3, ultrasonicating it at 35kHz for 30 minutes, taking it out and rinsing it with clean water until it is neutral, so as to obtain pretreated bamboo fiber; mixing the pretreated bamboo fiber with a potassium permanganate aqueous solution with a mass percentage of 0.5%, heating it to 70°C, adding acrylic acid dropwise at a speed of ^0.2m3 /h under stirring, and keeping the temperature for reaction for 1h after the addition is completed, filtering, and washing the bamboo fiber with an ethanol aqueous solution with a volume fraction of 30%, so as to obtain the pretreated bamboo fiber; the mass ratio of the pretreated bamboo fiber, potassium permanganate and acrylic acid is 17:1:5.

Example 2

An environmentally friendly composite board comprises the following components and their weight proportions:

Adhesive 40g, modified bamboo fiber 20g, polystyrene 35g, calcium oxide 15g, isopropyl titanate triisostearate 5g, polymethyl methacrylate 5g, anhydrous ethanol 20g;

The preparation method of the adhesive is as follows: 30g of deionized water and 12g of polysorbate are added to a three-necked flask, stirred, 25g of vinyl acetate and 8g of potassium persulfate are added, the temperature is raised to 75°C, 14g of vinyl triethoxysilane and 10g of ethyl methacrylate are added dropwise respectively, the dropping time is controlled within 1h, the temperature is continued to be raised to 95°C, reacted until no reflux liquid is generated, cooled to 55°C, 8g of propylene glycol, 8g of γ-aminopropyl triethoxysilane and 5g of 40% by mass sodium bicarbonate solution are added, and cooled to room temperature to obtain the adhesive.

The preparation method of the modified bamboo fiber is as follows: soaking the bamboo fiber in an acetic acid aqueous solution with a pH value of 5.5, taking it out and drying it; then adding it into a phosphoric acid aqueous solution with a pH value of 3.5, ultrasonicating it at 40kHz for 20 minutes, taking it out and rinsing it with clean water until it is neutral, so as to obtain pretreated bamboo fiber; mixing the pretreated bamboo fiber with a potassium permanganate aqueous solution with a mass percentage of 1%, heating it to 80°C, adding acrylic acid dropwise at a speed of ^1.5m3 /h under stirring, and keeping the temperature for reaction for 1.5h after the addition is completed, filtering it, and washing the bamboo fiber with an ethanol aqueous solution with a volume fraction of 30%, so as to obtain the pretreated bamboo fiber; the mass ratio of the pretreated bamboo fiber, potassium permanganate and acrylic acid is 20:3:9.

Example 3

An environmentally friendly composite board comprises the following components and their weight proportions:

36g of adhesive, 18g of modified bamboo fiber, 33g of polyvinyl chloride, 13g of filler, 4g of isopropyl titanate triisostearate, 4g of polymethyl methacrylate, and 26g of anhydrous ethanol; the filler is composed of calcium carbonate and calcium sulfate in a mass ratio of 1:1.

The preparation method of the adhesive is as follows: 36g of deionized water and 11g of polyvinyl alcohol are added to a three-necked flask, stirred, 23g of vinyl acetate and 7g of potassium persulfate are added, the temperature is raised to 73°C, 12g of vinyl triethoxysilane and 8g of ethyl methacrylate are added dropwise respectively, the dropping time is controlled within 0.8h, the temperature is continued to be raised to 93°C, reacted until no reflux liquid is generated, cooled to 53°C, 7g of propylene glycol, 7g of γ-aminopropyl triethoxysilane and 4g of 35% by mass sodium bicarbonate solution are added, and cooled to room temperature to obtain the adhesive.

The preparation method of the modified bamboo fiber is as follows: soaking the bamboo fiber in an acetic acid aqueous solution with a pH value of 5.2, taking it out and drying it; then adding it into a phosphoric acid aqueous solution with a pH value of 3.3, ultrasonicating it at 38kHz for 25 minutes, taking it out and rinsing it with clean water until it is neutral, so as to obtain pretreated bamboo fiber; mixing the pretreated bamboo fiber with a potassium permanganate aqueous solution with a mass percentage of 0.8%, heating it to 76°C, adding acrylic acid dropwise at a speed of ^1.0m3 /h under stirring, and keeping the temperature for reaction for 1.2h after the addition is completed, filtering it, and washing the bamboo fiber with an ethanol aqueous solution with a volume fraction of 30%, so as to obtain the pretreated bamboo fiber; the mass ratio of the pretreated bamboo fiber, potassium permanganate and acrylic acid is 19:2:7.

Comparative Example 1

The composite board described in this comparative example is similar to that in Example 3. The difference between this comparative example and Example 3 is that an equal amount of vinyl acetate is used instead of vinyl triethoxy silane in the preparation method of the adhesive in this comparative example.

Comparative Example 2

The composite board described in this comparative example is similar to that in Example 3. The difference between this comparative example and Example 3 is that an equal amount of vinyl acetate is used instead of ethyl methacrylate in the preparation method of the adhesive in this comparative example.

Comparative Example 3

The composite board described in this comparative example is similar to that in Example 3. The difference between this comparative example and Example 3 is that an equal amount of propylene glycol is used instead of γ-aminopropyltriethoxysilane in the preparation method of the adhesive in this comparative example.

Comparative Example 4

The composite board described in this comparative example is similar to that in Example 3. The difference between this comparative example and Example 3 is that in the preparation method of the modified bamboo fiber in this comparative example, an equal amount of deionized water is used instead of the phosphoric acid aqueous solution.

Comparative Example 5

The composite board described in this comparative example is similar to that in Example 3. The difference between this comparative example and Example 3 is that in the preparation method of the modified bamboo fiber in this comparative example, microwave treatment is used instead of ultrasonic treatment, the microwave frequency is 38 kHz, and the microwave time is 25 min.

Comparative Example 6

The composite board described in this comparative example is similar to that in Example 3. The difference between this comparative example and Example 3 is that in the preparation method of the modified bamboo fiber in this comparative example, the mass ratio of the pretreated bamboo fiber, potassium permanganate and acrylic acid is 2:7:16.

Test example

Mechanical properties test: The internal bonding strength of the composite boards prepared in Example 1 to Example 3 and Comparative Example 1 to Comparative Example 6 was measured in accordance with GB/T 11718-2021 "Medium Density Fiberboard" at humidity of 25°C, humidity of 30% and temperature of 40°C, humidity of 70%, respectively; the 2h water absorption expansion rate of the composite boards prepared in Example 1 to Example 3 and Comparative Example 1 to Comparative Example 6 was measured in accordance with GB/T 11718-2021 "Medium Density Fiberboard"; the test results are shown in Table 1.

Formaldehyde emission test: The formaldehyde emission of the environmentally friendly composite panels prepared in Examples 1 to 3 was measured in accordance with GB 18580-2017 "Indoor decoration and renovation materials - Formaldehyde emission limits in artificial boards and their products". The test results are shown in Table 2.

Table 1 Mechanical properties test results

It can be seen from Table 1 that the internal bonding strength of the environment-friendly composite board provided by the present invention at a temperature of 25°C and a humidity of 30% is 1.23-1.47 MPa, the internal bonding strength at a temperature of 40°C and a humidity of 70% is 1.04-1.22 MPa, the water absorption expansion rate of 2h is 3.2-4.1%, and the mechanical properties and water resistance are excellent, which indicates that the environment-friendly composite board provided by the present invention improves the compatibility of bamboo fiber and polymer, and improves the technical problem of deformation of the board caused by water absorption of bamboo fiber.

Compared with Example 3, Comparative Example 1 uses an equal amount of vinyl acetate instead of vinyl triethoxysilane, but the internal bonding strength of the prepared composite board at a temperature of 40°C and a humidity of 70% is significantly reduced, and the water absorption expansion rate of 2h is significantly increased, which indicates that the addition of vinyl triethoxysilane can not only improve the water resistance of the adhesive film, but also improve the heat resistance of the adhesive film.

Compared with Example 3, Comparative Example 2 uses an equal amount of vinyl acetate instead of ethyl methacrylate, but the internal bonding strength of the prepared composite board is slightly reduced, which shows that the addition of ethyl methacrylate can improve the cohesion of the adhesive, thereby improving the stability of the adhesive film.

Compared with Example 3, Comparative Example 3 uses an equal amount of propylene glycol instead of γ-aminopropyltriethoxysilane, but the internal bonding strength of the prepared composite board is reduced, which indicates that γ-aminopropyltriethoxysilane can simultaneously cross-link with the filler and the polymer to improve the internal bonding strength of the board.

Compared with Example 3, Comparative Example 4 uses an equal amount of deionized water instead of the phosphoric acid aqueous solution, but the internal bonding strength of the composite board obtained is reduced and the 2h water absorption rate is increased. This indicates that the phosphoric acid solution treatment of bamboo fiber can expose the cellulose in the bamboo fiber, and then cross-link with acrylic acid to further eliminate the highly water-absorbent hydroxyl groups in the bamboo fiber, while increasing the compatibility of the bamboo fiber with the polymer.

Compared with Example 3, Comparative Example 5 uses microwave treatment instead of ultrasonic treatment, but the internal bonding strength of the prepared composite board is slightly reduced and the 2h water absorption rate is slightly increased, which indicates that in the process of treating the fiber with phosphoric acid solution, the reaction effect under ultrasonic conditions is better.

Compared with Example 3, the mass ratio of pretreated bamboo fiber, potassium permanganate and acrylic acid in the preparation method of modified bamboo fiber in Example 6, but the internal bonding strength of the prepared composite board is reduced, and the 2h water absorption rate is increased, which indicates that the usage ratio of each component in the bamboo fiber modification process of the present invention has reached the optimization.

Table 2 Formaldehyde emission test results

It can be seen from Table 2 that the environment-friendly composite board provided by the present invention does not contain aldehyde adhesives and does not release formaldehyde during use, and has excellent environmental performance.

The above embodiments are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any person skilled in the art shall not modify the above embodiments without violating the spirit and scope of the present invention. Therefore, any modification, equivalent substitution and improvement made by those skilled in the art under the technical concept of the present invention shall still be covered by the claims of the present invention.

Claims (6)

1. The environment-friendly composite board is characterized by comprising the following components in parts by weight:

30-40 parts of adhesive, 15-20 parts of modified bamboo fiber, 30-35 parts of polymer resin, 10-15 parts of filler, 3-5 parts of isopropyl triisostearate titanate, 3-5 parts of polymethyl methacrylate and 20-30 parts of absolute ethyl alcohol;

the preparation method of the adhesive comprises the following steps: adding deionized water and an emulsifier into a three-neck flask, stirring, adding vinyl acetate and potassium persulfate, heating, respectively dropwise adding vinyl triethoxysilane and ethyl methacrylate, controlling the dropwise adding time to be within 0.6-1h, continuously heating, reacting until no reflux liquid is generated, reducing the temperature, adding propylene glycol, gamma-aminopropyl triethoxysilane and sodium bicarbonate solution, and cooling to room temperature to obtain the product;

The preparation method of the modified bamboo fiber comprises the following steps: soaking bamboo fiber in acetic acid water solution, taking out, and drying; then adding the bamboo fibers into a phosphoric acid aqueous solution, performing ultrasonic treatment, taking out, and washing the bamboo fibers with clear water until the bamboo fibers are neutral to obtain pretreated bamboo fibers; mixing the pretreated bamboo fiber with potassium permanganate aqueous solution, heating to 70-80 ℃, dropwise adding acrylic acid under stirring, carrying out heat preservation reaction for 1-1.5h after dropwise adding, filtering, and cleaning the bamboo fiber with ethanol aqueous solution to obtain the bamboo fiber;

the polymer resin is polyethylene, polypropylene, polystyrene or polyvinyl chloride;

The mass percentage of the potassium permanganate in the potassium permanganate aqueous solution is 0.5-1%; the dropping speed of the acrylic acid is 0.2-1.5m ³/h; the volume fraction of ethanol in the ethanol water solution is 30%; the mass ratio of the pretreated bamboo fiber to the potassium permanganate to the acrylic acid is 17-20:1-3:5-9.

2. The environment-friendly composite board according to claim 1, wherein the emulsifier in the preparation method of the adhesive is one of polyoxyethylene ether, polyvinyl alcohol and polysorbate.

3. The environment-friendly composite board according to claim 1, wherein the adhesive is prepared from the following components in percentage by weight: 30-40 parts of deionized water, 8-12 parts of emulsifying agent, 20-25 parts of vinyl acetate, 5-8 parts of potassium persulfate, 10-14 parts of vinyl triethoxysilane, 5-10 parts of ethyl methacrylate, 6-8 parts of propylene glycol, 6-8 parts of gamma-aminopropyl triethoxysilane and 3-5 parts of sodium bicarbonate solution; the mass percentage of the sodium bicarbonate solution is 30-40%.

4. The environment-friendly composite board according to claim 1, wherein in the preparation method of the adhesive, the temperature for heating is 70-75 ℃, the temperature for continuously heating is 90-95 ℃, and the temperature is reduced to 50-55 ℃.

5. The environment-friendly composite board according to claim 1, wherein the pH of the aqueous acetic acid solution is 5-5.5; the pH value of the phosphoric acid aqueous solution is 3-3.5, the ultrasonic frequency of the ultrasonic wave is 35-40kHz, and the ultrasonic time is 20-30min.

6. The environment-friendly composite board according to claim 1, wherein the filler is one or more of calcium carbonate, calcium sulfate, silicon dioxide, calcium oxide, diatomite and magnesium carbonate.