A biomimetic supramolecular water-resistant polyvinyl alcohol adhesive and its preparation method and application

Abstract

A bionic supramolecular water-resistant polyvinyl alcohol adhesive, a preparation method, and an application thereof, relates to an adhesive, a preparation method, and an application thereof. The present invention aims to solve the problems of free formaldehyde release in existing formaldehyde adhesives and difficulty in regulating the viscosity of formaldehyde-free supramolecular adhesive systems. The bionic supramolecular water-resistant polyvinyl alcohol adhesive is prepared from polyvinyl alcohol, tannic acid, a hydrogen bond regulator, and deionized water; the preparation method is as follows: polyvinyl alcohol and tannic acid are dissolved in a mixed solution of deionized water and a hydrogen bond regulator, and then heated and stirred until completely dissolved to obtain the bionic supramolecular water-resistant polyvinyl alcohol adhesive; the application is as follows: it is used as an adhesive or a protective layer for biomass materials. The present invention is used for a bionic supramolecular water-resistant polyvinyl alcohol adhesive, and its preparation and application.

Description

Technical Field

[0001] The invention relates to an adhesive and a preparation method and application thereof. Background Art

[0002] Currently, the adhesives widely used in the manufacture of wood-based panels are primarily formaldehyde adhesives, such as urea-formaldehyde, phenol-formaldehyde, or melamine-formaldehyde. While formaldehyde adhesives can ensure the dimensional stability and physical and mechanical properties of the panels, they also have significant disadvantages: the release of free formaldehyde can pollute the environment and harm human health.

[0003] Polyvinyl alcohol (PVA) is the world's largest-produced water-soluble polymer with excellent properties. Containing a polyhydroxyl molecular structure, it boasts an annual production capacity of up to 12 billion kilograms. Raw materials are plentiful, and large-scale production is possible through non-petroleum-based routes. It exhibits excellent adhesion, toughness, transparency, high film strength, oil resistance, corrosion resistance, solvent resistance, and abrasion resistance, as well as good gas barrier properties, thermal stability, and environmental friendliness. It is widely used in the production of coatings, emulsifiers, adhesives, textiles, paper processing agents, and plastic films. However, the excessive number of hydrophilic hydroxyl groups in PVA adhesives results in poor water resistance, limiting its application in wood-based panels.

[0004] In recent years, water-resistant adhesives inspired by mussel adhesive proteins have been widely reported and applied. These adhesives utilize catechol groups within the adhesive system and utilize these groups to form supramolecular interactions, such as hydrogen bonding, coordination bonding, and electrostatic interactions, on the surface of the substrate to produce strong water resistance and versatile adhesion. Tannic acid (TA), an abundant natural polyphenol extracted from plants, shares a catechol / pyrogallol unit structure with mussel adhesive proteins. Therefore, it can effectively form supramolecular interactions with the substrate, resulting in excellent water resistance.

[0005] The preparation of biomimetic supramolecular water-resistant adhesives by combining PVA and TA has promising application prospects. However, despite the excellent bonding properties of PVA / TA biomimetic supramolecular water-resistant adhesives, the viscosity of the composite system is difficult to control due to the uncontrollable supramolecular hydrogen bonding between PVA and TA (e.g., instant gelation occurs when the two are mixed in solution). This makes it difficult to evenly apply the adhesive to the surface of wood units (such as wood veneer and wood shavings), limiting its widespread application in the field of artificial panels (such as plywood and particleboard). Therefore, how to regulate the hydrogen bonding and viscosity of the PVA / TA biomimetic supramolecular system is the key to solving this problem. Summary of the Invention

[0006] The present invention aims to solve the problems of free formaldehyde release in existing formaldehyde adhesives and difficulty in controlling the viscosity of formaldehyde-free supramolecular adhesive systems, and further provides a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive and its preparation method and application.

[0007] A bionic supramolecular water-resistant polyvinyl alcohol adhesive is prepared from polyvinyl alcohol, tannic acid, a hydrogen bond regulator and deionized water;

[0008] The mass ratio of the polyvinyl alcohol to tannic acid is (2-5):1; the mass ratio of the polyvinyl alcohol to the total volume of deionized water and the hydrogen bond regulator is 1 g:(7-12) mL; and the volume ratio of the hydrogen bond regulator to deionized water is (0.2-0.5):1.

[0009] A method for preparing a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is carried out according to the following steps:

[0010] Dissolving polyvinyl alcohol and tannic acid in a mixed solution of deionized water and a hydrogen bond regulator, and then stirring at a temperature of 85° C. to 95° C. until the mixture is completely dissolved, thereby obtaining a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive;

[0011] The mass ratio of the polyvinyl alcohol to tannic acid is (2-5):1; the mass ratio of the polyvinyl alcohol to the total volume of deionized water and the hydrogen bond regulator is 1 g:(7-12) mL; and the volume ratio of the hydrogen bond regulator to deionized water is (0.2-0.5):1.

[0012] Application of a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive, which is used as an adhesive or a protective layer for biomass materials;

[0013] When used as an adhesive, bonding is performed according to the following steps:

[0014] The coating amount on one side is 250g / m 2 ~350g / m 2 , coating the biomimetic supramolecular water-resistant polyvinyl alcohol adhesive on the surface of the biomass unit, and then stacking, pre-pressing and hot-pressing to obtain plywood, thus completing the bonding method of the biomimetic supramolecular water-resistant polyvinyl alcohol adhesive;

[0015] Alternatively, the bionic supramolecular water-resistant polyvinyl alcohol adhesive is sprayed onto the wood chips at a concentration of 6% to 10% of the absolute dry wood chips mass, and then hot-pressed and cured to obtain a particleboard, thereby completing the bonding method of the bionic supramolecular water-resistant polyvinyl alcohol adhesive.

[0016] When used as a biomass material protective layer, it is specifically prepared according to the following steps:

[0017] The coating amount on one side is 200g / m 2 ~300g / m 2 The biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is coated on the surface of the biomass material, naturally dried and then heated to obtain a biomass material covered with a protective layer.

[0018] The beneficial effects of the present invention are:

[0019] (1) The adhesive is made of polyvinyl alcohol and tannic acid. Polyvinyl alcohol is a colorless, non-toxic, non-corrosive, biodegradable, water-soluble organic polymer that is rich in hydroxyl groups, relatively inexpensive, has good bonding strength, and is environmentally friendly. Tannic acid is a polyphenolic substance composed of phenolic hydroxyl groups (mainly), ester groups, and glucose. Its polyphenolic hydroxyl group structure gives it many unique chemical properties and physiological activities, and it can form physical cross-links with the hydroxyl groups on the polyvinyl alcohol molecular chain.

[0020] (2) It uses water as solvent and ethanol as hydrogen bond regulator. The raw materials are only polyvinyl alcohol and tannic acid. As a water-based adhesive, it does not contain any formaldehyde and volatile organic pollutants. It is a truly healthy and environmentally friendly adhesive that complies with the principle of atom economy.

[0021] (3) Simple process;

[0022] (4) The adhesive after biomimetic supramolecular bonding has high bonding strength and good water resistance (high wet bonding strength);

[0023] (5) By adjusting the ratio of water and hydrogen bonding modifier (ethanol), the hydrogen bonding of the polyvinyl alcohol / tannic acid supramolecular composite system can be regulated, thereby adjusting the macroscopic viscosity. This can be applied in many fields, such as plywood, particleboard, and coatings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A comparison chart of dry and wet bonding strength of plywood prepared in Examples 1 to 13 and Comparative Experiments 1 to 2;

[0025] Figure 2 Fourier transform infrared spectra of the biomimetic supramolecular water-resistant polyvinyl alcohol adhesive, PVA and TA prepared in Example 1;

[0026] Figure 3 The XPS spectra of the biomimetic supramolecular water-resistant polyvinyl alcohol adhesive prepared in Example 1 before and after thermal curing (heating at 180°C for 9 minutes), H-PT is after thermal curing, and PT is before thermal curing;

[0027] Figure 4 This is a comparison chart of the viscosity changes of biomimetic supramolecular water-resistant polyvinyl alcohol adhesives under different ethanol ratios;

[0028] Figure 5 A comparison chart of the static bending strength of particleboards prepared in Examples 14 to 18 and Comparative Experiment 3;

[0029] Figure 6 A comparison chart of the internal bonding strength of particleboards prepared in Examples 14 to 18 and Comparative Experiment 3. DETAILED DESCRIPTION

[0030] Specific embodiment 1: This embodiment is a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive, which is prepared from polyvinyl alcohol, tannic acid, a hydrogen bond regulator and deionized water;

[0031] The mass ratio of the polyvinyl alcohol to tannic acid is (2-5):1; the mass ratio of the polyvinyl alcohol to the total volume of deionized water and the hydrogen bond regulator is 1 g:(7-12) mL; and the volume ratio of the hydrogen bond regulator to deionized water is (0.2-0.5):1.

[0032] This specific embodiment uses a hydrogen bond modifier (ethanol) to dynamically regulate the hydrogen bond crosslinking between polyvinyl alcohol (PVA) and tannic acid. By introducing this hydrogen bond modifier (ethanol) into a PVA / TA aqueous adhesive system to construct a hydrogen bond modifier / water hybrid system, the hydrogen bond barrier effect of the hydrogen bond modifier (ethanol) in the PVA / TA composite system is utilized to regulate the hydrogen bonding between tannic acid and PVA, controlling the viscosity of the PVA / TA composite system and preparing a biomimetic supramolecular water-resistant PVA adhesive suitable for bonding wood-based panels. Furthermore, viscosity control enables applications in particleboard and coatings.

[0033] The beneficial effects of this embodiment are:

[0034] (1) The adhesive is made of polyvinyl alcohol and tannic acid. Polyvinyl alcohol is a colorless, non-toxic, non-corrosive, biodegradable, water-soluble organic polymer that is rich in hydroxyl groups, relatively inexpensive, has good bonding strength, and is environmentally friendly. Tannic acid is a polyphenolic substance composed of phenolic hydroxyl groups (mainly), ester groups, and glucose. Its polyphenolic hydroxyl group structure gives it many unique chemical properties and physiological activities, and it can form physical cross-links with the hydroxyl groups on the polyvinyl alcohol molecular chain.

[0035] (2) It uses water as solvent and ethanol as hydrogen bond regulator. The raw materials are only polyvinyl alcohol and tannic acid. As a water-based adhesive, it does not contain any formaldehyde and volatile organic pollutants. It is a truly healthy and environmentally friendly adhesive that complies with the principle of atom economy.

[0036] (3) Simple process;

[0037] (4) The adhesive after biomimetic supramolecular bonding has high bonding strength and good water resistance (high wet bonding strength);

[0038] (5) By adjusting the ratio of water and hydrogen bonding modifier (ethanol), the hydrogen bonding of the polyvinyl alcohol / tannic acid supramolecular composite system can be regulated, thereby adjusting the macroscopic viscosity. This can be applied in many fields, such as plywood, particleboard, and coatings.

[0039] Specific embodiment 2: This embodiment differs from specific embodiment 1 in that the molecular weight of the polyvinyl alcohol is 10,000 to 300,000, and the alcoholysis degree of the polyvinyl alcohol is 80% to 100%. Other aspects are the same as specific embodiment 1.

[0040] Specific embodiment 3: This embodiment differs from specific embodiment 1 or 2 in that the hydrogen bond modifier is ethanol. Other aspects are the same as specific embodiment 1 or 2.

[0041] Specific embodiment 4: This embodiment is a method for preparing a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive, which is carried out according to the following steps:

[0042] Dissolving polyvinyl alcohol and tannic acid in a mixed solution of deionized water and a hydrogen bond regulator, and then stirring at a temperature of 85° C. to 95° C. until the mixture is completely dissolved, thereby obtaining a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive;

[0043] The mass ratio of the polyvinyl alcohol to tannic acid is (2-5):1; the mass ratio of the polyvinyl alcohol to the total volume of deionized water and the hydrogen bond regulator is 1 g:(7-12) mL; and the volume ratio of the hydrogen bond regulator to deionized water is (0.2-0.5):1.

[0044] Specific embodiment 5: This embodiment differs from specific embodiment 4 in that the molecular weight of the polyvinyl alcohol is 10,000 to 300,000, and the alcoholysis degree of the polyvinyl alcohol is 80% to 100%. Other aspects are the same as specific embodiment 4.

[0045] Specific embodiment 6: This embodiment differs from specific embodiment 4 or 5 in that the hydrogen bond modifier is ethanol. Other aspects are the same as specific embodiment 4 or 5.

[0046] Specific embodiment seven: This embodiment is an application of a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive, which is used as an adhesive or a protective layer of biomass materials;

[0047] When used as an adhesive, bonding is performed according to the following steps:

[0048] The coating amount on one side is 250g / m 2 ~350g / m 2 , coating the biomimetic supramolecular water-resistant polyvinyl alcohol adhesive on the surface of the biomass unit, and then stacking, pre-pressing and hot-pressing to obtain plywood, thus completing the bonding method of the biomimetic supramolecular water-resistant polyvinyl alcohol adhesive;

[0049] Alternatively, the bionic supramolecular water-resistant polyvinyl alcohol adhesive is sprayed onto the wood chips at a concentration of 6% to 10% of the absolute dry wood chips mass, and then hot-pressed and cured to obtain a particleboard, thereby completing the bonding method of the bionic supramolecular water-resistant polyvinyl alcohol adhesive.

[0050] When used as a biomass material protective layer, it is specifically prepared according to the following steps:

[0051] The coating amount on one side is 200g / m 2 ~300g / m 2 The biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is coated on the surface of the biomass material, naturally dried and then heated to obtain a biomass material covered with a protective layer.

[0052] Specific embodiment eight: This embodiment differs from specific embodiment seven in that the biomass units are biomass single boards, biomass panels, or biomass lattice panels, and the wood chips are biomass wood chips. Other aspects are the same as specific embodiment seven.

[0053] Specific embodiment 9: This embodiment differs from specific embodiment 7 or 8 in that when the plywood is obtained, the pre-pressing is performed at room temperature and a pressure of 0.1 MPa to 3.0 MPa for 4 to 8 hours. Other aspects are the same as specific embodiment 7 or 8.

[0054] Specific embodiment 10: This embodiment differs from specific embodiments 7 to 9 in that: when obtaining plywood, the hot pressing curing is performed under conditions of a pressure of 0.2 MPa to 1.2 MPa and a temperature of 150°C to 210°C for 5 to 10 minutes; when obtaining particleboard, the hot pressing curing is performed under conditions of a pressure of 2 MPa to 4 MPa and a temperature of 190°C to 240°C for 5 to 10 minutes; when obtaining biomass material covered with a protective layer, the heating is performed at a temperature of 120°C to 170°C for 5 to 15 minutes. Other aspects are the same as specific embodiments 7 to 9.

[0055] The following examples are used to verify the beneficial effects of the present invention:

[0056] (1) Plywood preparation:

[0057] Example 1:

[0058] A method for preparing a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is carried out according to the following steps:

[0059] Polyvinyl alcohol and tannic acid were dissolved in a mixed solution of deionized water and a hydrogen bond regulator, and then stirred at 90°C for 3 hours until completely dissolved, thereby obtaining a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive.

[0060] The mass ratio of the polyvinyl alcohol to tannic acid is 4:1; the mass ratio of the polyvinyl alcohol to the total volume of deionized water and the hydrogen bond regulator is 1 g:9.6 mL; and the volume ratio of the hydrogen bond regulator to deionized water is 0.35:1.

[0061] The molecular weight of the polyvinyl alcohol is 70,000 to 80,000, and the alcoholysis degree of the polyvinyl alcohol is 98% to 99%.

[0062] The hydrogen bond regulator is ethanol.

[0063] The bonding method of the above-mentioned biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is carried out according to the following steps:

[0064] The coating amount on one side is 300g / m 2 , applying the bionic supramolecular water-resistant polyvinyl alcohol adhesive to the surface of the wooden units, and then stacking, pre-pressing and hot-pressing and curing to obtain plywood, thus completing the bonding method of the bionic supramolecular water-resistant polyvinyl alcohol adhesive;

[0065] The wooden unit is a poplar veneer obtained by rotary cutting.

[0066] The pre-pressing is specifically carried out at room temperature and a pressure of 1.0 MPa for 4 hours.

[0067] The hot pressing curing is specifically carried out under the conditions of a pressure of 1 MPa and a temperature of 180° C. for 9 minutes.

[0068] Example 2:

[0069] A method for preparing a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is carried out according to the following steps:

[0070] Polyvinyl alcohol and tannic acid were dissolved in a mixed solution of deionized water and a hydrogen bond regulator, and then stirred at 90°C for 3 hours until completely dissolved, thereby obtaining a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive.

[0071] The mass ratio of the polyvinyl alcohol to tannic acid is 3:1; the mass ratio of the polyvinyl alcohol to the total volume of deionized water and the hydrogen bond regulator is 1 g:9.6 mL; and the volume ratio of the hydrogen bond regulator to deionized water is 0.35:1.

[0072] The molecular weight of the polyvinyl alcohol is 70,000 to 80,000, and the alcoholysis degree of the polyvinyl alcohol is 98% to 99%.

[0073] The hydrogen bond regulator is ethanol.

[0074] The bonding method of the above-mentioned biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is carried out according to the following steps:

[0075] The coating amount on one side is 300g / m 2 , applying the bionic supramolecular water-resistant polyvinyl alcohol adhesive to the surface of the wooden units, and then stacking, pre-pressing and hot-pressing and curing to obtain plywood, thus completing the bonding method of the bionic supramolecular water-resistant polyvinyl alcohol adhesive;

[0076] The wooden unit is a poplar veneer obtained by rotary cutting.

[0077] The pre-pressing is specifically carried out at room temperature and a pressure of 2.0 MPa for 4 hours.

[0078] The hot pressing curing is specifically carried out under the conditions of a pressure of 1 MPa and a temperature of 180° C. for 9 minutes.

[0079] Example 3:

[0080] A method for preparing a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is carried out according to the following steps:

[0081] Polyvinyl alcohol and tannic acid were dissolved in a mixed solution of deionized water and a hydrogen bond regulator, and then stirred at 90°C for 3 hours until completely dissolved, thereby obtaining a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive.

[0082] The mass ratio of the polyvinyl alcohol to tannic acid is 5:1; the mass ratio of the polyvinyl alcohol to the total volume of deionized water and the hydrogen bond regulator is 1 g:10 mL; the volume ratio of the hydrogen bond regulator to deionized water is 0.4:1;

[0083] The molecular weight of the polyvinyl alcohol is 70,000 to 80,000, and the alcoholysis degree of the polyvinyl alcohol is 98% to 99%.

[0084] The hydrogen bond regulator is ethanol.

[0085] The bonding method of the above-mentioned biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is carried out according to the following steps:

[0086] The coating amount on one side is 320g / m 2 , applying the bionic supramolecular water-resistant polyvinyl alcohol adhesive to the surface of the wooden units, and then stacking, pre-pressing and hot-pressing and curing to obtain plywood, thus completing the bonding method of the bionic supramolecular water-resistant polyvinyl alcohol adhesive;

[0087] The wooden unit is a poplar veneer obtained by rotary cutting.

[0088] The pre-pressing is specifically carried out at room temperature and a pressure of 1.0 MPa for 4 hours.

[0089] The hot pressing curing is specifically carried out under the conditions of a pressure of 1 MPa and a temperature of 150° C. for 9 minutes.

[0090] Example 4:

[0091] A method for preparing a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is carried out according to the following steps:

[0092] Polyvinyl alcohol and tannic acid were dissolved in a mixed solution of deionized water and a hydrogen bond regulator, and then stirred at 90°C for 3 hours until completely dissolved, thereby obtaining a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive.

[0093] The mass ratio of the polyvinyl alcohol to tannic acid is 4:1; the mass ratio of the polyvinyl alcohol to the total volume of deionized water and the hydrogen bond regulator is 1 g:7 mL; the volume ratio of the hydrogen bond regulator to deionized water is 0.4:1;

[0094] The molecular weight of the polyvinyl alcohol is 70,000 to 80,000, and the alcoholysis degree of the polyvinyl alcohol is 98% to 99%.

[0095] The hydrogen bond regulator is ethanol.

[0096] The bonding method of the above-mentioned biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is carried out according to the following steps:

[0097] The coating amount on one side is 280g / m 2 , applying the bionic supramolecular water-resistant polyvinyl alcohol adhesive to the surface of the wooden units, and then stacking, pre-pressing and hot-pressing and curing to obtain plywood, thus completing the bonding method of the bionic supramolecular water-resistant polyvinyl alcohol adhesive;

[0098] The wooden unit is a poplar veneer obtained by rotary cutting.

[0099] The pre-pressing is specifically carried out at room temperature and a pressure of 3.0 MPa for 4 hours.

[0100] The hot pressing curing is specifically carried out under the conditions of a pressure of 1 MPa and a temperature of 150° C. for 9 minutes.

[0101] Example 5:

[0102] A method for preparing a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is carried out according to the following steps:

[0103] Polyvinyl alcohol and tannic acid were dissolved in a mixed solution of deionized water and a hydrogen bond regulator, and then stirred at 90°C for 3 hours until completely dissolved, thereby obtaining a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive.

[0104] The mass ratio of the polyvinyl alcohol to tannic acid is 3:1; the mass ratio of the polyvinyl alcohol to the total volume of deionized water and the hydrogen bond modifier is 1 g:7 mL; the volume ratio of the hydrogen bond modifier to deionized water is 0.45:1;

[0105] The molecular weight of the polyvinyl alcohol is 70,000 to 80,000, and the alcoholysis degree of the polyvinyl alcohol is 98% to 99%.

[0106] The hydrogen bond regulator is ethanol.

[0107] The bonding method of the above-mentioned biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is carried out according to the following steps:

[0108] The coating amount on one side is 300g / m 2 , applying the bionic supramolecular water-resistant polyvinyl alcohol adhesive to the surface of the wooden units, and then stacking, pre-pressing and hot-pressing and curing to obtain plywood, thus completing the bonding method of the bionic supramolecular water-resistant polyvinyl alcohol adhesive;

[0109] The wooden unit is a poplar veneer obtained by rotary cutting.

[0110] The pre-pressing is specifically performed at room temperature and a pressure of 0.1 MPa for 4 hours.

[0111] The hot pressing curing is specifically performed under the conditions of a pressure of 1 MPa and a temperature of 180° C. for 10 minutes.

[0112] Example 6:

[0113] A method for preparing a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is carried out according to the following steps:

[0114] Polyvinyl alcohol and tannic acid were dissolved in a mixed solution of deionized water and a hydrogen bond regulator, and then stirred at 90°C for 3 hours until completely dissolved, thereby obtaining a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive.

[0115] The mass ratio of the polyvinyl alcohol to tannic acid is 5:1; the mass ratio of the polyvinyl alcohol to the total volume of deionized water and the hydrogen bond regulator is 1 g:8 mL; the volume ratio of the hydrogen bond regulator to deionized water is 0.35:1;

[0116] The molecular weight of the polyvinyl alcohol is 13,000 to 23,000, and the alcoholysis degree of the polyvinyl alcohol is 87% to 89%.

[0117] The hydrogen bond regulator is ethanol.

[0118] The bonding method of the above-mentioned biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is carried out according to the following steps:

[0119] The coating amount on one side is 310g / m 2 , applying the bionic supramolecular water-resistant polyvinyl alcohol adhesive to the surface of the wooden units, and then stacking, pre-pressing and hot-pressing and curing to obtain plywood, thus completing the bonding method of the bionic supramolecular water-resistant polyvinyl alcohol adhesive;

[0120] The wooden unit is a poplar veneer obtained by rotary cutting.

[0121] The pre-pressing is specifically carried out at room temperature and a pressure of 1.0 MPa for 4 hours.

[0122] The hot pressing curing is specifically performed under the conditions of a pressure of 1.2 MPa and a temperature of 160° C. for 10 minutes.

[0123] Example 7:

[0124] A method for preparing a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is carried out according to the following steps:

[0125] Polyvinyl alcohol and tannic acid were dissolved in a mixed solution of deionized water and a hydrogen bond regulator, and then stirred at 90°C for 3 hours until completely dissolved, thereby obtaining a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive.

[0126] The mass ratio of the polyvinyl alcohol to tannic acid is 4:1; the mass ratio of the polyvinyl alcohol to the total volume of deionized water and the hydrogen bond modifier is 1 g:9.6 mL; the volume ratio of the hydrogen bond modifier to deionized water is 0.35:1;

[0127] The molecular weight of the polyvinyl alcohol is 30,000 to 70,000, and the alcoholysis degree of the polyvinyl alcohol is 87% to 89%.

[0128] The hydrogen bond regulator is ethanol.

[0129] The bonding method of the above-mentioned biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is carried out according to the following steps:

[0130] The coating amount on one side is 300g / m 2 , applying the bionic supramolecular water-resistant polyvinyl alcohol adhesive to the surface of the wooden units, and then stacking, pre-pressing and hot-pressing and curing to obtain plywood, thus completing the bonding method of the bionic supramolecular water-resistant polyvinyl alcohol adhesive;

[0131] The wooden unit is a poplar veneer obtained by rotary cutting.

[0132] The pre-pressing is specifically carried out at room temperature and a pressure of 1.0 MPa for 4 hours.

[0133] The hot pressing curing is specifically carried out under the conditions of a pressure of 1 MPa and a temperature of 180° C. for 9 minutes.

[0134] Example 8:

[0135] A method for preparing a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is carried out according to the following steps:

[0136] Polyvinyl alcohol and tannic acid were dissolved in a mixed solution of deionized water and a hydrogen bond regulator, and then stirred at 90°C for 3 hours until completely dissolved, thereby obtaining a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive.

[0137] The mass ratio of the polyvinyl alcohol to tannic acid is 4:1; the mass ratio of the polyvinyl alcohol to the total volume of deionized water and the hydrogen bond modifier is 1 g:9.6 mL; the volume ratio of the hydrogen bond modifier to deionized water is 0.35:1;

[0138] The molecular weight of the polyvinyl alcohol is 85,000 to 124,000, and the alcoholysis degree of the polyvinyl alcohol is 98% to 99%.

[0139] The hydrogen bond regulator is ethanol.

[0140] The bonding method of the above-mentioned biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is carried out according to the following steps:

[0141] The coating amount on one side is 300g / m 2 , applying the bionic supramolecular water-resistant polyvinyl alcohol adhesive to the surface of the wooden units, and then stacking, pre-pressing and hot-pressing and curing to obtain plywood, thus completing the bonding method of the bionic supramolecular water-resistant polyvinyl alcohol adhesive;

[0142] The wooden unit is a beech veneer obtained by rotary cutting.

[0143] The pre-pressing is specifically carried out at room temperature and a pressure of 1.0 MPa for 4 hours.

[0144] The hot pressing curing is specifically carried out under the conditions of a pressure of 1 MPa and a temperature of 180° C. for 9 minutes.

[0145] Example 9:

[0146] A method for preparing a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is carried out according to the following steps:

[0147] Polyvinyl alcohol and tannic acid were dissolved in a mixed solution of deionized water and a hydrogen bond regulator, and then stirred at 90°C for 3 hours until completely dissolved, thereby obtaining a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive.

[0148] The mass ratio of the polyvinyl alcohol to tannic acid is 4:1; the mass ratio of the polyvinyl alcohol to the total volume of deionized water and the hydrogen bond modifier is 1 g:9.6 mL; the volume ratio of the hydrogen bond modifier to deionized water is 0.35:1;

[0149] The molecular weight of the polyvinyl alcohol is 70,000 to 80,000, and the alcoholysis degree of the polyvinyl alcohol is 98% to 99%.

[0150] The hydrogen bond regulator is ethanol.

[0151] The bonding method of the above-mentioned biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is carried out according to the following steps:

[0152] The coating amount on one side is 300g / m 2 , applying the bionic supramolecular water-resistant polyvinyl alcohol adhesive to the surface of the wooden units, and then stacking, pre-pressing and hot-pressing and curing to obtain plywood, thus completing the bonding method of the bionic supramolecular water-resistant polyvinyl alcohol adhesive;

[0153] The wooden unit is a birch veneer obtained by rotary cutting.

[0154] The pre-pressing is specifically carried out at room temperature and a pressure of 1.0 MPa for 4 hours.

[0155] The hot pressing curing is specifically carried out under the conditions of a pressure of 1 MPa and a temperature of 180° C. for 9 minutes.

[0156] Example 10:

[0157] A method for preparing a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is carried out according to the following steps:

[0158] Polyvinyl alcohol and tannic acid were dissolved in a mixed solution of deionized water and a hydrogen bond regulator, and then stirred at 90°C for 3 hours until completely dissolved, thereby obtaining a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive.

[0159] The mass ratio of the polyvinyl alcohol to tannic acid is 4:1; the mass ratio of the polyvinyl alcohol to the total volume of deionized water and the hydrogen bond modifier is 1 g:9.6 mL; the volume ratio of the hydrogen bond modifier to deionized water is 0.35:1;

[0160] The molecular weight of the polyvinyl alcohol is 70,000 to 80,000, and the alcoholysis degree of the polyvinyl alcohol is 98% to 99%.

[0161] The hydrogen bond regulator is ethanol.

[0162] The bonding method of the above-mentioned biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is carried out according to the following steps:

[0163] The coating amount on one side is 300g / m 2 , applying the bionic supramolecular water-resistant polyvinyl alcohol adhesive to the surface of the wooden units, and then stacking, pre-pressing and hot-pressing and curing to obtain plywood, thus completing the bonding method of the bionic supramolecular water-resistant polyvinyl alcohol adhesive;

[0164] The wooden unit is a basswood veneer obtained by rotary cutting.

[0165] The pre-pressing is specifically carried out at room temperature and a pressure of 1.0 MPa for 4 hours.

[0166] The hot pressing curing is specifically carried out under the conditions of a pressure of 1 MPa and a temperature of 180° C. for 9 minutes.

[0167] Example 11:

[0168] A method for preparing a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is carried out according to the following steps:

[0169] Polyvinyl alcohol and tannic acid were dissolved in a mixed solution of deionized water and a hydrogen bond regulator, and then stirred at 90°C for 3 hours until completely dissolved, thereby obtaining a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive.

[0170] The mass ratio of the polyvinyl alcohol to tannic acid is 4:1; the mass ratio of the polyvinyl alcohol to the total volume of deionized water and the hydrogen bond regulator is 1 g:9.6 mL; and the volume ratio of the hydrogen bond regulator to deionized water is 0.4:1.

[0171] The molecular weight of the polyvinyl alcohol is 70,000 to 80,000, and the alcoholysis degree of the polyvinyl alcohol is 98% to 99%.

[0172] The hydrogen bond regulator is ethanol.

[0173] The bonding method of the above-mentioned biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is carried out according to the following steps:

[0174] The coating amount on one side is 300g / m 2 , applying the bionic supramolecular water-resistant polyvinyl alcohol adhesive to the surface of the wooden units, and then stacking, pre-pressing and hot-pressing and curing to obtain plywood, thus completing the bonding method of the bionic supramolecular water-resistant polyvinyl alcohol adhesive;

[0175] The wooden unit is a poplar veneer obtained by rotary cutting.

[0176] The pre-pressing is specifically carried out at room temperature and a pressure of 1.0 MPa for 4 hours.

[0177] The hot pressing curing is specifically carried out under the conditions of a pressure of 1 MPa and a temperature of 180° C. for 9 minutes.

[0178] Example 12:

[0179] A method for preparing a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is carried out according to the following steps:

[0180] Polyvinyl alcohol and tannic acid were dissolved in a mixed solution of deionized water and a hydrogen bond regulator, and then stirred at 90°C for 3 hours until completely dissolved, thereby obtaining a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive.

[0181] The mass ratio of the polyvinyl alcohol to tannic acid is 4:1; the mass ratio of the polyvinyl alcohol to the total volume of deionized water and the hydrogen bond regulator is 1 g:9.6 mL; and the volume ratio of the hydrogen bond regulator to deionized water is 0.45:1.

[0182] The molecular weight of the polyvinyl alcohol is 70,000 to 80,000, and the alcoholysis degree of the polyvinyl alcohol is 98% to 99%.

[0183] The hydrogen bond regulator is ethanol.

[0184] The bonding method of the above-mentioned biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is carried out according to the following steps:

[0185] The coating amount on one side is 300g / m 2 , applying the bionic supramolecular water-resistant polyvinyl alcohol adhesive to the surface of the wooden units, and then stacking, pre-pressing and hot-pressing and curing to obtain plywood, thus completing the bonding method of the bionic supramolecular water-resistant polyvinyl alcohol adhesive;

[0186] The wooden unit is a poplar veneer obtained by rotary cutting.

[0187] The pre-pressing is specifically carried out at room temperature and a pressure of 1.0 MPa for 4 hours.

[0188] The hot pressing curing is specifically carried out under the conditions of a pressure of 1 MPa and a temperature of 180° C. for 9 minutes.

[0189] Example 13:

[0190] A method for preparing a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is carried out according to the following steps:

[0191] Polyvinyl alcohol and tannic acid were dissolved in a mixed solution of deionized water and a hydrogen bond regulator, and then stirred at 90°C for 3 hours until completely dissolved, thereby obtaining a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive.

[0192] The mass ratio of the polyvinyl alcohol to tannic acid is 4:1; the mass ratio of the polyvinyl alcohol to the total volume of deionized water and the hydrogen bond regulator is 1 g:9.6 mL; and the volume ratio of the hydrogen bond regulator to deionized water is 0.5:1.

[0193] The molecular weight of the polyvinyl alcohol is 70,000 to 80,000, and the alcoholysis degree of the polyvinyl alcohol is 98% to 99%.

[0194] The hydrogen bond regulator is ethanol.

[0195] The bonding method of the above-mentioned biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is carried out according to the following steps:

[0196] The coating amount on one side is 300g / m 2 , applying the bionic supramolecular water-resistant polyvinyl alcohol adhesive to the surface of the wooden units, and then stacking, pre-pressing and hot-pressing and curing to obtain plywood, thus completing the bonding method of the bionic supramolecular water-resistant polyvinyl alcohol adhesive;

[0197] The wooden unit is a poplar veneer obtained by rotary cutting.

[0198] The pre-pressing is specifically carried out at room temperature and a pressure of 1.0 MPa for 4 hours.

[0199] The hot pressing curing is specifically carried out under the conditions of a pressure of 1 MPa and a temperature of 180° C. for 9 minutes.

[0200] Comparative Experiment 1 was conducted in the following steps:

[0201] Dissolve polyvinyl alcohol and tannic acid in deionized water, and then stir at 90°C for 3 hours until completely dissolved to obtain a polyvinyl alcohol adhesive;

[0202] The mass ratio of the polyvinyl alcohol to tannic acid is 4:1; the volume ratio of the polyvinyl alcohol to deionized water is 1 g:9.6 mL;

[0203] The molecular weight of the polyvinyl alcohol is 70,000 to 80,000, and the alcoholysis degree of the polyvinyl alcohol is 98% to 99%.

[0204] The bonding method of the above-mentioned polyvinyl alcohol adhesive is carried out according to the following steps:

[0205] The coating amount on one side is 300g / m 2 , applying polyvinyl alcohol adhesive to the surface of wooden units, then stacking, pre-pressing and hot-pressing to obtain plywood, thus completing the bonding method of polyvinyl alcohol adhesive;

[0206] The wooden unit is a poplar veneer obtained by rotary cutting.

[0207] The pre-pressing is specifically carried out at room temperature and a pressure of 1.0 MPa for 4 hours.

[0208] The hot pressing curing is specifically carried out under the conditions of a pressure of 1 MPa and a temperature of 180° C. for 9 minutes.

[0209] Comparative Experiment 2 was conducted as follows:

[0210] Dissolving polyvinyl alcohol in a mixed solution of deionized water and a hydrogen bond regulator, and then stirring at 90° C. for 3 hours until completely dissolved, to obtain a polyvinyl alcohol adhesive;

[0211] The mass ratio of the polyvinyl alcohol to the total volume of deionized water and the hydrogen bond modifier is 1 g:9.6 mL; the volume ratio of the hydrogen bond modifier to deionized water is 0.5:1;

[0212] The molecular weight of the polyvinyl alcohol is 70,000 to 80,000, and the alcoholysis degree of the polyvinyl alcohol is 98% to 99%.

[0213] The hydrogen bond regulator is ethanol.

[0214] The bonding method of the above-mentioned polyvinyl alcohol adhesive is carried out according to the following steps:

[0215] The coating amount on one side is 300g / m 2 , applying polyvinyl alcohol adhesive to the surface of wooden units, then stacking, pre-pressing and hot-pressing to obtain plywood, thus completing the bonding method of polyvinyl alcohol adhesive;

[0216] The wooden unit is a poplar veneer obtained by rotary cutting.

[0217] The pre-pressing is specifically carried out at room temperature and a pressure of 1.0 MPa for 4 hours.

[0218] The hot pressing curing is specifically carried out under the conditions of a pressure of 1 MPa and a temperature of 180° C. for 9 minutes.

[0219] The adhesive prepared by comparative experiment 1 will produce gelation phenomenon, making gluing difficult, while the adhesive prepared by comparative experiment 2 has poor water resistance and does not meet national standards.

[0220] (2) Preparation of particleboard:

[0221] Example 14:

[0222] A method for preparing a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is carried out according to the following steps:

[0223] Polyvinyl alcohol and tannic acid were dissolved in a mixed solution of deionized water and a hydrogen bond regulator, and then stirred at 90°C for 3 hours until completely dissolved, thereby obtaining a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive.

[0224] The mass ratio of the polyvinyl alcohol to tannic acid is 4:1; the mass ratio of the polyvinyl alcohol to the total volume of deionized water and the hydrogen bond regulator is 1 g:12 mL; the volume ratio of the hydrogen bond regulator to deionized water is 0.35:1;

[0225] The molecular weight of the polyvinyl alcohol is 70,000 to 80,000, and the alcoholysis degree of the polyvinyl alcohol is 98% to 99%.

[0226] The hydrogen bond regulator is ethanol.

[0227] The bonding method of the above-mentioned biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is carried out according to the following steps:

[0228] Spraying a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive onto the wood chips at 8% of the absolute dry wood chip mass, laying fine wood chips on the upper and lower layers, laying coarse wood chips on the middle layer, and then hot-pressing and curing to obtain a particleboard, thus completing the bonding method of the biomimetic supramolecular water-resistant polyvinyl alcohol adhesive;

[0229] The wood shavings are poplar wood shavings.

[0230] The hot pressing curing is specifically carried out under the conditions of a pressure of 3 MPa and a temperature of 210° C. for 5 minutes.

[0231] The thickness of the fine wood shavings on the upper and lower surface layers is 8mm to 12mm, and the thickness of the coarse wood shavings on the middle layer is 15mm to 18mm; the dimensions of the coarse wood shavings are: length 15mm to 45mm, width 3mm to 10mm, and thickness 0.4mm to 0.7mm; the dimensions of the fine wood shavings are: length 3mm to 15mm, width 0.5mm to 1.5mm, and thickness 0.2mm to 0.4mm.

[0232] Example 15:

[0233] A method for preparing a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is carried out according to the following steps:

[0234] Polyvinyl alcohol and tannic acid were dissolved in a mixed solution of deionized water and a hydrogen bond regulator, and then stirred at 90°C for 3 hours until completely dissolved, thereby obtaining a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive.

[0235] The mass ratio of the polyvinyl alcohol to tannic acid is 3:1; the mass ratio of the polyvinyl alcohol to the total volume of deionized water and the hydrogen bond regulator is 1 g:11 mL; the volume ratio of the hydrogen bond regulator to deionized water is 0.25:1;

[0236] The molecular weight of the polyvinyl alcohol is 70,000 to 80,000, and the alcoholysis degree of the polyvinyl alcohol is 98% to 99%.

[0237] The hydrogen bond regulator is ethanol.

[0238] The bonding method of the above-mentioned biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is carried out according to the following steps:

[0239] Spraying a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive onto the wood chips at 8% of the absolute dry wood chip mass, laying fine wood chips on the upper and lower layers, laying coarse wood chips on the middle layer, and then hot-pressing and curing to obtain a particleboard, thus completing the bonding method of the biomimetic supramolecular water-resistant polyvinyl alcohol adhesive;

[0240] The wood shavings are poplar wood shavings.

[0241] The hot pressing curing is specifically carried out under the conditions of a pressure of 3 MPa and a temperature of 190° C. for 7 minutes.

[0242] The thickness of the fine wood shavings on the upper and lower surface layers is 8mm to 12mm, and the thickness of the coarse wood shavings on the middle layer is 15mm to 18mm; the dimensions of the coarse wood shavings are: length 15mm to 45mm, width 3mm to 10mm, and thickness 0.4mm to 0.7mm; the dimensions of the fine wood shavings are: length 3mm to 15mm, width 0.5mm to 1.5mm, and thickness 0.2mm to 0.4mm.

[0243] Example 16:

[0244] A method for preparing a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is carried out according to the following steps:

[0245] Polyvinyl alcohol and tannic acid were dissolved in a mixed solution of deionized water and a hydrogen bond regulator, and then stirred at 90°C for 3 hours until completely dissolved, thereby obtaining a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive.

[0246] The mass ratio of the polyvinyl alcohol to tannic acid is 4:1; the mass ratio of the polyvinyl alcohol to the total volume of deionized water and the hydrogen bond regulator is 1 g:12 mL; the volume ratio of the hydrogen bond regulator to deionized water is 0.4:1;

[0247] The molecular weight of the polyvinyl alcohol is 85,000 to 124,000, and the alcoholysis degree of the polyvinyl alcohol is 98% to 99%.

[0248] The hydrogen bond regulator is ethanol.

[0249] The bonding method of the above-mentioned biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is carried out according to the following steps:

[0250] Spraying a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive onto the wood chips at 9% of the absolute dry wood chip mass, laying fine wood chips on the upper and lower layers, laying coarse wood chips on the middle layer, and then hot-pressing and curing to obtain a particleboard, thus completing the bonding method of the biomimetic supramolecular water-resistant polyvinyl alcohol adhesive;

[0251] The wood shavings are poplar wood shavings.

[0252] The hot pressing curing is specifically carried out under the conditions of a pressure of 4 MPa and a temperature of 240° C. for 5 minutes.

[0253] The thickness of the fine wood shavings on the upper and lower surface layers is 8mm to 12mm, and the thickness of the coarse wood shavings on the middle layer is 15mm to 18mm; the dimensions of the coarse wood shavings are: length 15mm to 45mm, width 3mm to 10mm, and thickness 0.4mm to 0.7mm; the dimensions of the fine wood shavings are: length 3mm to 15mm, width 0.5mm to 1.5mm, and thickness 0.2mm to 0.4mm.

[0254] Example 17:

[0255] A method for preparing a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is carried out according to the following steps:

[0256] Polyvinyl alcohol and tannic acid were dissolved in a mixed solution of deionized water and a hydrogen bond regulator, and then stirred at 90°C for 3 hours until completely dissolved, thereby obtaining a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive.

[0257] The mass ratio of the polyvinyl alcohol to tannic acid is 4:1; the mass ratio of the polyvinyl alcohol to the total volume of deionized water and the hydrogen bond regulator is 1 g:9.6 mL; and the volume ratio of the hydrogen bond regulator to deionized water is 0.3:1.

[0258] The molecular weight of the polyvinyl alcohol is 70,000 to 80,000, and the alcoholysis degree of the polyvinyl alcohol is 98% to 99%.

[0259] The hydrogen bond regulator is ethanol.

[0260] The bonding method of the above-mentioned biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is carried out according to the following steps:

[0261] Spraying a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive onto the wood chips at 8% of the absolute dry wood chip mass, laying fine wood chips on the upper and lower layers, laying coarse wood chips on the middle layer, and then hot-pressing and curing to obtain a particleboard, thus completing the bonding method of the biomimetic supramolecular water-resistant polyvinyl alcohol adhesive;

[0262] The wood shavings are poplar wood shavings.

[0263] The hot pressing curing is specifically carried out under the conditions of a pressure of 3 MPa and a temperature of 210° C. for 5 minutes.

[0264] The thickness of the fine wood shavings on the upper and lower surface layers is 8mm to 12mm, and the thickness of the coarse wood shavings on the middle layer is 15mm to 18mm; the dimensions of the coarse wood shavings are: length 15mm to 45mm, width 3mm to 10mm, and thickness 0.4mm to 0.7mm; the dimensions of the fine wood shavings are: length 3mm to 15mm, width 0.5mm to 1.5mm, and thickness 0.2mm to 0.4mm.

[0265] Example 18:

[0266] A method for preparing a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is carried out according to the following steps:

[0267] Polyvinyl alcohol and tannic acid were dissolved in a mixed solution of deionized water and a hydrogen bond regulator, and then stirred at 90°C for 3 hours until completely dissolved, thereby obtaining a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive.

[0268] The mass ratio of the polyvinyl alcohol to tannic acid is 4:1; the mass ratio of the polyvinyl alcohol to the total volume of deionized water and the hydrogen bond regulator is 1 g:9.6 mL; and the volume ratio of the hydrogen bond regulator to deionized water is 0.2:1.

[0269] The molecular weight of the polyvinyl alcohol is 70,000 to 80,000, and the alcoholysis degree of the polyvinyl alcohol is 98% to 99%.

[0270] The hydrogen bond regulator is ethanol.

[0271] The bonding method of the above-mentioned biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is carried out according to the following steps:

[0272] Spraying a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive onto the wood chips at 8% of the absolute dry wood chip mass, laying fine wood chips on the upper and lower layers, laying coarse wood chips on the middle layer, and then hot-pressing and curing to obtain a particleboard, thus completing the bonding method of the biomimetic supramolecular water-resistant polyvinyl alcohol adhesive;

[0273] The wood shavings are poplar wood shavings.

[0274] The hot pressing curing is specifically carried out under the conditions of a pressure of 3 MPa and a temperature of 210° C. for 5 minutes.

[0275] The thickness of the fine wood shavings on the upper and lower surface layers is 8mm to 12mm, and the thickness of the coarse wood shavings on the middle layer is 15mm to 18mm; the dimensions of the coarse wood shavings are: length 15mm to 45mm, width 3mm to 10mm, and thickness 0.4mm to 0.7mm; the dimensions of the fine wood shavings are: length 3mm to 15mm, width 0.5mm to 1.5mm, and thickness 0.2mm to 0.4mm.

[0276] Comparative Experiment 3 was conducted in the following steps:

[0277] Polyvinyl alcohol is dissolved in a mixed solution of deionized water and a hydrogen bond regulator, and then stirred at 90°C for 3 hours until it is completely dissolved to obtain a polyvinyl alcohol adhesive;

[0278] The mass ratio of the polyvinyl alcohol to the total volume of deionized water and the hydrogen bond modifier is 1 g:12 mL; the volume ratio of the hydrogen bond modifier to deionized water is 0.35:1;

[0279] The molecular weight of the polyvinyl alcohol is 70,000 to 80,000, and the alcoholysis degree of the polyvinyl alcohol is 98% to 99%.

[0280] The hydrogen bond regulator is ethanol.

[0281] The bonding method of the above-mentioned polyvinyl alcohol adhesive is carried out according to the following steps:

[0282] Applying sizing agent at a percentage of 8% of the absolute dry wood shavings mass, spraying polyvinyl alcohol adhesive onto the wood shavings, laying fine wood shavings on the upper and lower layers, laying coarse wood shavings on the middle layer, and then hot pressing and curing to obtain particleboard, thus completing the polyvinyl alcohol adhesive bonding method;

[0283] The wood shavings are poplar wood shavings.

[0284] The hot pressing curing is specifically carried out under the conditions of a pressure of 3 MPa and a temperature of 210° C. for 5 minutes.

[0285] The thickness of the fine wood shavings on the upper and lower surface layers is 8mm to 12mm, and the thickness of the coarse wood shavings on the middle layer is 15mm to 18mm; the dimensions of the coarse wood shavings are: length 15mm to 45mm, width 3mm to 10mm, and thickness 0.4mm to 0.7mm; the dimensions of the fine wood shavings are: length 3mm to 15mm, width 0.5mm to 1.5mm, and thickness 0.2mm to 0.4mm.

[0286] (3) Preparation of wood protective layer:

[0287] Example 19:

[0288] A method for preparing a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is carried out according to the following steps:

[0289] Polyvinyl alcohol and tannic acid were dissolved in a mixed solution of deionized water and a hydrogen bond regulator, and then stirred at 90°C for 3 hours until completely dissolved, thereby obtaining a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive.

[0290] The mass ratio of the polyvinyl alcohol to tannic acid is 4:1; the mass ratio of the polyvinyl alcohol to the total volume of deionized water and the hydrogen bond modifier is 1 g:9.6 mL; the volume ratio of the hydrogen bond modifier to deionized water is 0.35:1;

[0291] The molecular weight of the polyvinyl alcohol is 70,000 to 80,000, and the alcoholysis degree of the polyvinyl alcohol is 98% to 99%.

[0292] The hydrogen bond regulator is ethanol.

[0293] The method for preparing the biomimetic supramolecular water-resistant polyvinyl alcohol adhesive used as a wood protective layer is carried out according to the following steps:

[0294] The coating amount on one side is 260g / m 2 , the bionic supramolecular water-resistant polyvinyl alcohol adhesive was coated on the surface of poplar wood, dried naturally and then heated to obtain wood covered with a protective layer.

[0295] The heating is specifically carried out at a temperature of 150° C. for 5 min, 10 min and 15 min respectively.

[0296] Example 20:

[0297] A method for preparing a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is carried out according to the following steps:

[0298] Polyvinyl alcohol and tannic acid were dissolved in a mixed solution of deionized water and a hydrogen bond regulator, and then stirred at 90°C for 3 hours until completely dissolved, thereby obtaining a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive.

[0299] The mass ratio of the polyvinyl alcohol to tannic acid is 4:1; the mass ratio of the polyvinyl alcohol to the total volume of deionized water and the hydrogen bond regulator is 1 g:10 mL; the volume ratio of the hydrogen bond regulator to deionized water is 0.4:1;

[0300] The molecular weight of the polyvinyl alcohol is 70,000 to 80,000, and the alcoholysis degree of the polyvinyl alcohol is 98% to 99%.

[0301] The hydrogen bond regulator is ethanol.

[0302] The method for preparing the biomimetic supramolecular water-resistant polyvinyl alcohol adhesive used as a wood protective layer is carried out according to the following steps:

[0303] The coating amount on one side is 280g / m 2 , the bionic supramolecular water-resistant polyvinyl alcohol adhesive was coated on the surface of poplar wood, dried naturally and then heated to obtain wood covered with a protective layer.

[0304] The heating is specifically carried out at a temperature of 120° C. for 5 min, 10 min and 15 min respectively.

[0305] Example 21:

[0306] A method for preparing a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is carried out according to the following steps:

[0307] Polyvinyl alcohol and tannic acid were dissolved in a mixed solution of deionized water and a hydrogen bond regulator, and then stirred at 90°C for 3 hours until completely dissolved, thereby obtaining a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive.

[0308] The mass ratio of the polyvinyl alcohol to tannic acid is 3:1; the mass ratio of the polyvinyl alcohol to the total volume of deionized water and the hydrogen bond regulator is 1 g:8 mL; the volume ratio of the hydrogen bond regulator to deionized water is 0.4:1;

[0309] The molecular weight of the polyvinyl alcohol is 70,000 to 80,000, and the alcoholysis degree of the polyvinyl alcohol is 98% to 99%.

[0310] The hydrogen bond regulator is ethanol.

[0311] The method for preparing the biomimetic supramolecular water-resistant polyvinyl alcohol adhesive used as a wood protective layer is carried out according to the following steps:

[0312] The coating amount on one side is 270g / m 2 , the bionic supramolecular water-resistant polyvinyl alcohol adhesive was coated on the surface of poplar wood, dried naturally and then heated to obtain wood covered with a protective layer.

[0313] The heating is specifically carried out at a temperature of 170° C. for 5 min, 10 min and 15 min respectively.

[0314] Example 22:

[0315] A method for preparing a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is carried out according to the following steps:

[0316] Polyvinyl alcohol and tannic acid were dissolved in a mixed solution of deionized water and a hydrogen bond regulator, and then stirred at 90°C for 3 hours until completely dissolved, thereby obtaining a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive.

[0317] The mass ratio of the polyvinyl alcohol to tannic acid is 4:1; the mass ratio of the polyvinyl alcohol to the total volume of deionized water and the hydrogen bond regulator is 1 g:9.6 mL; and the volume ratio of the hydrogen bond regulator to deionized water is 0.25:1.

[0318] The molecular weight of the polyvinyl alcohol is 70,000 to 80,000, and the alcoholysis degree of the polyvinyl alcohol is 98% to 99%.

[0319] The hydrogen bond regulator is ethanol.

[0320] The method for preparing the biomimetic supramolecular water-resistant polyvinyl alcohol adhesive used as a wood protective layer is carried out according to the following steps:

[0321] The coating amount on one side is 260g / m 2 , the bionic supramolecular water-resistant polyvinyl alcohol adhesive was coated on the surface of poplar wood, dried naturally and then heated to obtain wood covered with a protective layer.

[0322] The heating is specifically carried out at a temperature of 150° C. for 5 min, 10 min and 15 min respectively.

[0323] Example 23:

[0324] A method for preparing a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is carried out according to the following steps:

[0325] Polyvinyl alcohol and tannic acid were dissolved in a mixed solution of deionized water and a hydrogen bond regulator, and then stirred at 90°C for 3 hours until completely dissolved, thereby obtaining a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive.

[0326] The mass ratio of the polyvinyl alcohol to tannic acid is 4:1; the mass ratio of the polyvinyl alcohol to the total volume of deionized water and the hydrogen bond regulator is 1 g:10 mL; and the volume ratio of the hydrogen bond regulator to deionized water is 0.2:1.

[0327] The molecular weight of the polyvinyl alcohol is 70,000 to 80,000, and the alcoholysis degree of the polyvinyl alcohol is 98% to 99%.

[0328] The hydrogen bond regulator is ethanol.

[0329] The method for preparing the biomimetic supramolecular water-resistant polyvinyl alcohol adhesive used as a wood protective layer is carried out according to the following steps:

[0330] The coating amount on one side is 260g / m 2 , the bionic supramolecular water-resistant polyvinyl alcohol adhesive was coated on the surface of poplar wood, dried naturally and then heated to obtain wood covered with a protective layer.

[0331] The heating is specifically carried out at a temperature of 150° C. for 5 min, 10 min and 15 min respectively.

[0332] Comparative Experiment 4 was conducted in the following steps:

[0333] Dissolving polyvinyl alcohol in a mixed solution of deionized water and a hydrogen bond regulator, and then stirring at 90° C. for 3 hours until completely dissolved, to obtain a polyvinyl alcohol adhesive;

[0334] The mass ratio of the polyvinyl alcohol to the total volume of deionized water and the hydrogen bond modifier is 1 g:9.6 mL; the volume ratio of the hydrogen bond modifier to deionized water is 0.35:1;

[0335] The molecular weight of the polyvinyl alcohol is 70,000 to 80,000, and the alcoholysis degree of the polyvinyl alcohol is 98% to 99%.

[0336] The hydrogen bond regulator is ethanol.

[0337] The above-mentioned polyvinyl alcohol adhesive is used as a method for preparing a wood protective layer, which is carried out according to the following steps:

[0338] The coating amount on one side is 260g / m 2 , polyvinyl alcohol adhesive is applied to the surface of poplar wood, naturally dried and then heated to obtain wood covered with a protective layer.

[0339] The heating is specifically carried out at a temperature of 150° C. for 5 min, 10 min and 15 min respectively.

[0340] 1. Bonding strength test:

[0341] Test specimens were prepared according to the national standard GB / T17657-2013. The wood grain of the core board between the glue layers was perpendicular to the length of the specimen. The slot width and depth of the specimens were designed to comply with the dimensions and requirements outlined in the national standard. For dry strength, the sawn standard specimens required no additional processing. Tensile and shear strength were measured directly on a universal testing machine with a 10 kN force transducer and a tensile speed of 5 mm / min. For wet strength, the prepared specimens were boiled in 63°C water for 3 hours, then immersed in cold water for 10 minutes to cool. The tensile and shear strength tests were then performed using the same universal testing machine procedures as for dry strength.

[0342] Figure 1The figure shows a comparison of the dry and wet bonding strengths of the plywood prepared in Examples 1 to 13 and Comparative Experiments 1 to 2. As can be seen from the figure, the dry bonding strengths of the bionic supramolecular water-resistant polyvinyl alcohol adhesive (PT) prepared in Examples 1 to 13 are 1.91, 1.58, 1.44, 1.31, 1.39, 1.51, 1.62, 2.11, 2.23, 1.99, 1.77, 1.83, and 1.87 MPa, respectively, which are much higher than those of the control group, indicating that the PT adhesive has excellent bonding properties. As can be seen from the figure, the wet bonding strengths of the bionic supramolecular water-resistant polyvinyl alcohol adhesive (PT) prepared in Examples 1 to 13 are 1.4, 0.98, 0.88, 0.79, 0.82, 0.90, 1.00, 1.52, 1.56, 1.48, 1.30, 1.33, and 1.37 MPa, respectively, all of which meet the national standard (≥0.7 MPa). The performance is much improved compared to the control group, indicating that the PT adhesive has excellent water resistance.

[0343] 2. Infrared analysis:

[0344] Figure 2 The Fourier transform infrared spectra of the biomimetic supramolecular water-resistant polyvinyl alcohol adhesive, PVA and TA prepared in Example 1; PT in the figure is the biomimetic supramolecular water-resistant polyvinyl alcohol adhesive prepared in Example 1; It can be seen from the figure that 3297cm -1 and 1030cm -1 The absorption peaks at 3275cm represent the -OH and C-OH stretching vibrations of TA. -1 and 1084cm -1 The absorption peaks at 1700 cm-1 in the PT spectrum represent the -OH and C-OH stretching vibrations of PVA. -1 The absorption peak at 1607 cm -1 New characteristic absorption peaks appear at 100 nm, due to the stretching vibrations of C=C and C=O. Compared to the OH and C-OH absorption peaks of PVA, both absorption peaks in PT shift to lower wavenumbers. This is due to the intermolecular hydrogen bonds formed by crosslinking PVA and TA. The formation of intermolecular hydrogen bonds reduces the force constant of the chemical bond, causing its vibration frequency to red-shift.

[0345] 3. XPS analysis:

[0346] Figure 3These XPS spectra show the biomimetic supramolecular water-resistant polyvinyl alcohol adhesive prepared in Example 1 before and after heat curing (heating at 180°C for 9 minutes). H-PT shows the post-curing period, while PT shows the pre-curing period. The figure shows that the OH content in the uncured PT adhesive is 60.73% and the COC / C-OH ratio is 27.86%. However, the OH content in the cured PT adhesive is 50.01% and the COC / C-OH ratio is 38.22%, indicating that OH bonds break down and convert to COC / C-OH bonds during the curing process.

[0347] 4. Viscosity control:

[0348] Figure 4 The figure shows a comparison of the viscosity changes of the biomimetic supramolecular water-resistant polyvinyl alcohol adhesive under different ethanol ratios. When the volume ratio of ethanol to deionized water is 0.2:1 (Example 18), 0.25:1 (Example 22), 0.3:1 (Example 17), 0.35:1 (Example 1), 0.4:1 (Example 11), 0.45:1 (Example 12), and 0.5:1 (Example 13), the corresponding viscosities of the biomimetic supramolecular water-resistant polyvinyl alcohol adhesive are 698, 735, 665, 443, 663, 795, and 1200 MPa·s, respectively. These adhesives can be used in the preparation of plywood, particleboard, and coatings. However, the PVA / TA supramolecular adhesive without alcohol is in a gel state and cannot be used.

[0349] 5. Static bending strength of particleboard:

[0350] Tested according to GB / T17657-2022 standard; Figure 5 The static bending strength comparison chart of the particleboard prepared in Examples 14 to 18 and Comparative Experiment 3 is shown; as can be seen from the figure, the static bending strength of the particleboard prepared by the adhesive in the examples is 16.31, 16.0, 16.7, 16.1, and 15.8 MPa, respectively, which meets and exceeds the national standard (≥11.5 MPa). Compared with the static bending strength of 8.41 MPa of the control group, it is significantly improved and has excellent bending resistance.

[0351] 6. Bonding strength within particleboard:

[0352] Tested according to GB / T17657-2022 standard; Figure 6 This is a comparison chart of the internal bonding strength of particleboards prepared in Examples 14 to 18 and Comparative Experiment 3; it can be seen from the figure that the internal bonding strength of the particleboards prepared by the adhesives in the examples are 1.58, 1.50, 1.68, 1.52, and 1.40 MPa, respectively, which meet and exceed the national standard (≥0.3 MPa). Compared with the internal bonding strength of 0.60 MPa in the control group, it has been significantly improved and has excellent internal bonding performance.

[0353] 7. Coating peel strength:

[0354] Table 1 Effect of curing time on peel strength of wood surface coating

[0355]

[0356]

[0357] Tests were conducted according to GB / T17657-2022. Coating peel strength reflects the bond strength between the coating and the wood surface. Good peel strength ensures the coating provides long-term protection for the wood. Table 1 shows that when the curing time reaches 15 minutes, the failure interface of the example specimens is completely wood failure, while the failure interface of the comparative experimental specimens is only mixed failure. This demonstrates that the biomimetic supramolecular water-resistant polyvinyl alcohol adhesive possesses excellent peel resistance as a wood coating, and its bond strength meets the requirements.

[0358] 8. Coating pencil hardness:

[0359] Table 2 Effect of curing time on the hardness of wood surface coating

[0360]

[0361] Testing was conducted according to GB / T17657-2022. Hardness reflects a coating's resistance to external forces such as indentation, cutting, and scratching, and is an important mechanical property of a coating. Table 2 shows that after 15 minutes of curing, the Example coatings all achieved a pencil hardness rating of 6H, the highest possible. However, after 15 minutes of curing, the control coatings only achieved a pencil hardness rating of 4H. This demonstrates that the Example adhesives possess excellent coating hardness for use as wood coatings.

Claims

1. A biomimetic supramolecular water-resistant polyvinyl alcohol adhesive, characterized in that It is prepared from polyvinyl alcohol, tannic acid, hydrogen bond regulator and deionized water; The mass ratio of the polyvinyl alcohol to tannic acid is (3-5):1; the mass ratio of the polyvinyl alcohol to the total volume of deionized water and the hydrogen bond regulator is 1 g:(7-12) mL; the volume ratio of the hydrogen bond regulator to deionized water is (0.2-0.5):1; The molecular weight of the polyvinyl alcohol is 10,000 to 300,000, and the alcoholysis degree of the polyvinyl alcohol is 80% to 100%; The hydrogen bond modifier is ethanol; The preparation method of the above-mentioned biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is carried out according to the following steps: Dissolving polyvinyl alcohol and tannic acid in a mixed solution of deionized water and a hydrogen bond regulator, and then stirring at a temperature of 85° C. to 95° C. until the mixture is completely dissolved, thereby obtaining a biomimetic supramolecular water-resistant polyvinyl alcohol adhesive; The application of the above-mentioned biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is used as an adhesive or a protective layer for biomass materials; When used as an adhesive, bonding is performed according to the following steps: The coating amount on one side is 250g / m 2 ~350g / m 2 , applying the biomimetic supramolecular water-resistant polyvinyl alcohol adhesive to the surface of the biomass unit, then stacking, pre-pressing and hot-pressing to obtain plywood, thus completing the bonding method of the biomimetic supramolecular water-resistant polyvinyl alcohol adhesive; the pre-pressing is specifically performed at room temperature and a pressure of 0.1 MPa to 3.0 MPa for 4 to 8 hours; the hot-pressing curing is specifically performed at a pressure of 0.2 MPa to 1.2 MPa and a temperature of 150° C. to 210° C. for 5 to 10 minutes; Alternatively, a bionic supramolecular water-resistant polyvinyl alcohol adhesive is sprayed onto the wood chips at a rate of 6% to 10% of the absolute dry wood chips mass, and then hot-pressed to cure the chips to obtain a particleboard, thereby completing the bonding method of the bionic supramolecular water-resistant polyvinyl alcohol adhesive; the hot-pressing curing is specifically performed under conditions of a pressure of 2 MPa to 4 MPa and a temperature of 190° C. to 240° C. for 5 to 10 minutes; When used as a biomass material protective layer, it is specifically prepared according to the following steps: The coating amount on one side is 200g / m 2 ~300g / m 2 The biomimetic supramolecular water-resistant polyvinyl alcohol adhesive is applied to the surface of the biomass material, and the biomass material is naturally dried and then heated to obtain a biomass material covered with a protective layer; the heating is specifically performed at a temperature of 120° C. to 170° C. for 5 min to 15 min.

2. The biomimetic supramolecular water-resistant polyvinyl alcohol adhesive according to claim 1, characterized in that The biomass unit is a biomass single board, a biomass plywood or a biomass lattice structure board; the wood chips are biomass wood chips.

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