Formaldehyde-free waterproof flame-retardant glue formula

Abstract

The invention discloses a formaldehyde-free waterproof flame-retardant glue formula which comprises the following necessary components in parts by weight: 40-60 parts of a formaldehyde-free body component, 15-25 parts of a phosphorus-nitrogen synergistic flame-retardant component, 5-12 parts of a waterproof modified component, 2-6 parts of a crosslinking aid, 1-3 parts of a stabilizer and 10-20 parts of deionized water. According to the invention, ethylene diamine tetraacetic acid or sodium citrate is added as a stabilizer, so that the out-of-control polymerization of furfuryl alcohol and the layering of each component can be effectively inhibited, and the storage stability of the glue is improved; the filler is added after being pretreated by the silane coupling agent, so that the mechanical strength and the water resistance of the glue are further improved, the production cost can be reduced, and both the performance and the economical efficiency are considered; the dosage of each component is optimized and screened, the proportion is scientific, the synergism and unification of formaldehyde-free, waterproof, flame-retardant, high strength and high stability are realized, and the comprehensive performance is superior to that of the existing formaldehyde-free adhesive.

Description

Technical Field

[0001] This invention relates to the field of adhesive formulation technology, and in particular to a formaldehyde-free, waterproof, and flame-retardant adhesive formulation. Background Technology

[0002] Adhesives are core auxiliary materials in fields such as engineered wood products, furniture manufacturing, and building decoration. Their usage is enormous and their applications are widespread, directly impacting the performance and safety of end products. With increasingly stringent environmental policies and heightened public awareness of health, traditional formaldehyde-containing adhesives (such as urea-formaldehyde resin and phenolic resin) are gradually being replaced by formaldehyde-free adhesives because they continuously release formaldehyde during use, harming human health and polluting the environment.

[0003] Currently, existing formaldehyde-free adhesives are mainly divided into two categories: bio-based formaldehyde-free adhesives (such as starch-based, tannin-based, and furfuryl alcohol-based) and synthetic formaldehyde-free adhesives (such as polyurethane-based and epoxy resin-based). However, there are still many technical pain points, making it difficult to achieve the three core properties of formaldehyde-free, waterproof, and flame-retardant. Furthermore, their practicality and economy need to be improved. Firstly, while bio-based formaldehyde-free adhesives are environmentally friendly, they generally suffer from poor water resistance and insufficient bonding strength. Most products have a 24-hour water absorption rate exceeding 10%, making them unsuitable for humid environments. Secondly, existing flame-retardant formaldehyde-free adhesives often use a single flame retardant, resulting in limited flame-retardant effects (limiting oxygen index mostly below 30%). Furthermore, the poor compatibility between the flame retardant and the adhesive matrix easily leads to adhesive delamination, decreased storage stability, and further reduced bonding strength. Thirdly, some formaldehyde-free adhesives still use strong acids as catalysts to improve reaction efficiency, which easily leads to substrate degradation, adhesive yellowing, and the migration of acidic components, reducing waterproof performance and service life. Fourthly, while synthetic formaldehyde-free adhesives have relatively stable performance, their production costs are high, the preparation process is complex, requiring high temperature and pressure conditions, resulting in high energy consumption and difficulty in large-scale promotion. Fifthly, existing formaldehyde-free adhesives often focus on optimizing a single performance aspect, either only achieving formaldehyde-free environmental friendliness or only improving waterproof or flame-retardant properties, failing to achieve a synergistic balance of formaldehyde-free, waterproof, flame-retardant, high strength, and low cost, making it difficult to meet the practical application needs of fields such as engineered wood products and building decoration.

[0004] Therefore, in view of the performance shortcomings of existing formaldehyde-free adhesives, developing a formaldehyde-free, waterproof and flame-retardant adhesive formulation that is free of formaldehyde and strong acid catalysis, has excellent waterproof and flame-retardant properties and high bonding strength, and is easy to prepare, cost-controllable and mass-producible has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, one of the objectives of this invention is to provide a formaldehyde-free waterproof and flame-retardant adhesive formula.

[0006] One of the objectives of this invention is achieved through the following technical solution: The formaldehyde-free, waterproof, and flame-retardant adhesive formulation, by weight, includes the following essential components: 40-60 parts of formaldehyde-free matrix component, 15-25 parts of phosphorus-nitrogen synergistic flame-retardant component, 5-12 parts of waterproof modifying component, 2-6 parts of crosslinking aid, 1-3 parts of stabilizer, and 10-20 parts of deionized water; the formulation contains no formaldehyde-releasing components or strong acid catalysts, and the formaldehyde release is ≤0.02mg / m³. 3 The 24-hour water absorption rate is ≤8%, the limiting oxygen index is ≥32%, and the bonding strength is ≥1.5MPa, meeting the GB / T9846-2015 and GB8624-2012 B1 flame retardant standards.

[0007] Furthermore, the formaldehyde-free matrix component is a composite bio-based system, composed of tannins, modified furfuryl alcohol, and oxidized polyvinyl alcohol in a weight ratio of 1:0.3-0.6:0.1-0.2; the tannins are selected from black thorn tannins or larch tannins, with a number average molecular weight of 1200-2500 g / mol; the modified furfuryl alcohol is polyethylene glycol monomethyl ether modified furfuryl alcohol, with a number average molecular weight of 400-1000 g / mol, and the modification amount is 8%-15% of the mass of furfuryl alcohol; the oxidized polyvinyl alcohol has an oxidation degree of 20%-35% and a number average molecular weight of 3.0 × 10⁻⁶. 4 -5.0×10 4 g / mol.

[0008] Furthermore, the phosphorus-nitrogen synergistic flame retardant component is a composite system, composed of a phosphorus-containing intumescent flame retardant and a nitrogen-based flame retardant in a weight ratio of 2:1-1.5; the phosphorus-containing intumescent flame retardant is selected from N,N-bis(2,2-dimethyl-1,3-propanediol phosphate)urea (DDPPU) or (1-oxo-1-phospha-2,6,7-trioxabicyclo(2.2.2)octane-4-carbonyl)neopentyl glycol ester (DOPCP); the nitrogen-based flame retardant is selected from one or two of melamine cyanurate and melamine phosphate in any proportion.

[0009] Furthermore, the waterproofing modified component includes a silane coupling agent and phytic acid, with a weight ratio of 1:0.8-1.2; the silane coupling agent is selected from KH-550 and KH-560; the phytic acid has a mass fraction of 70%-80%, serving as a mild acid catalyst and waterproofing auxiliary component to avoid substrate degradation caused by the migration of acidic components.

[0010] Furthermore, the crosslinking aid is selected from cationic polyacrylamide and carboxylated polyacrylamide, with a number average molecular weight of 2.5 × 10⁻⁶. 6 -3.5×10 6 g / mol; the stabilizer is selected from disodium ethylenediaminetetraacetate and sodium citrate, and is used to inhibit the runaway polymerization of furfuryl alcohol and component stratification.

[0011] Furthermore, it also includes 3-8 parts of filler, wherein the filler is selected from one or more of diatomaceous earth, kaolin, and calcium carbonate and mixed in any proportion, the filler particle size is 1000-2000 mesh, and it is added after pretreatment with silane coupling agent to improve the mechanical strength and water resistance of the adhesive.

[0012] Furthermore, the preferred weight proportions of each component are: 50 parts of formaldehyde-free matrix component, 20 parts of phosphorus-nitrogen synergistic flame retardant component, 8 parts of waterproof modification component, 4 parts of crosslinking aid, 2 parts of stabilizer, 15 parts of deionized water, and 5 parts of filler.

[0013] Furthermore, this includes the following steps: (1) Weigh all components by weight, add tannin and deionized water from the formaldehyde-free matrix component to the reaction vessel, and stir at 300-500 r / min for 15-25 min at room temperature until the tannin is completely dissolved. (2) Add modified furfuryl alcohol and stabilizer to the reaction vessel, heat to 50-60℃, stir for 30-40 min to obtain aldehyde-free matrix solution; (3) Add the phosphorus-nitrogen synergistic flame retardant component, waterproof modification component and crosslinking aid to the formaldehyde-free matrix solution in sequence, keep the temperature at 50-60℃ and stir for 60-90min to form a uniformly dispersed mixed system; (4) If filler is added, the pretreated filler is added to the above mixing system, and stirring is continued for 20-30 minutes. The mixture is then cooled to room temperature, filtered to remove impurities, and formaldehyde-free waterproof and flame-retardant adhesive is obtained. The entire preparation process does not require high temperature and high pressure, and there is no harmful gas emission, which can realize large-scale production.

[0014] Furthermore, the adhesive can be used in fields such as engineered wood products (plywood, particleboard, fiberboard), furniture manufacturing, building decoration, and packaging materials. It can be applied using cold pressing or hot pressing processes, with cold pressing temperatures of 20-40℃ and hot pressing temperatures of 100-120℃. The application is convenient, energy-saving, and environmentally friendly.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The formula of this invention does not contain any formaldehyde-releasing components or strong acid catalysts, and the formaldehyde release is ≤0.02mg / m³. 3 It is far below industry standards, emits no harmful gases during use, and meets environmental protection policies and human health requirements; at the same time, through reasonable component matching, it avoids problems such as substrate degradation and glue yellowing caused by strong acid catalysis, and improves the storage stability and service life of the glue.

[0016] 2. This invention employs a phosphorus-nitrogen synergistic flame-retardant component, with the two components combined in a specific ratio to achieve complementary flame-retardant effects. The limiting oxygen index is ≥32%, meeting the GB8624-2012 B1 flame-retardant standard. Compared to a single flame-retardant system, it exhibits higher flame-retardant efficiency, longer-lasting flame-retardant effect, and is less prone to flame-retardant migration. Simultaneously, the silane coupling agent and phytic acid in the waterproofing modifier work synergistically. Phytic acid acts as a mild acid catalyst to promote the reaction and also helps improve waterproof performance. The silane coupling agent improves the compatibility of each component and enhances the adhesion between the adhesive and the substrate, resulting in an adhesive water absorption rate of ≤8% over 24 hours. This significantly outperforms existing bio-based formaldehyde-free adhesives and meets the application requirements of humid environments.

[0017] 3. This invention uses a composite bio-based formaldehyde-free matrix composed of tannins, modified furfuryl alcohol, and oxidized polyvinyl alcohol, combined with cationic or carboxylated polyacrylamide crosslinking aids, which can significantly improve the bonding performance and mechanical strength of the adhesive. The bonding strength is ≥1.5MPa, which meets the GB / T9846-2015 standard. It is suitable for various artificial boards such as plywood, particleboard, and fiberboard, as well as furniture manufacturing, building decoration and other fields, with a wide range of applications.

[0018] 4. The preparation process of this invention does not require high temperature and high pressure conditions. The reaction can be completed at room temperature to 60°C. It has low energy consumption, simple operation, no harmful gas emissions, and high production safety. The components use bio-based raw materials (tannin, furfuryl alcohol, etc.), which are widely available and low in cost. Combined with conventional flame retardants and waterproofing components, the overall production cost is lower than that of synthetic formaldehyde-free adhesives. Moreover, the components have good compatibility, the preparation process is stable, and it is easy to realize large-scale industrial production.

[0019] 5. This invention effectively inhibits the runaway polymerization of furfuryl alcohol and the stratification of its components by adding disodium ethylenediaminetetraacetate or sodium citrate as stabilizers, thereby improving the storage stability of the adhesive. The filler is added after pretreatment with a silane coupling agent, which not only further improves the mechanical strength and water resistance of the adhesive, but also reduces production costs, balancing performance and economy. The dosage of each component has been optimized and screened, and the proportions are scientific, achieving a synergistic unity of formaldehyde-free, waterproof, flame-retardant, high strength, and high stability, with overall performance superior to existing formaldehyde-free adhesives.

[0020] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0021] Figure 1 This is a flowchart of this embodiment. Detailed Implementation

[0022] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0023] It should be noted that when a component is described as "fixed to" another component, it can be directly on the other component or may have a component in between. When a component is considered "connected to" another component, it can be directly connected to the other component or may have a component in between. When a component is considered "set on" another component, it can be directly set on the other component or may have a component in between. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0025] Example 1 1. Components and weight parts: 50 parts of formaldehyde-free matrix component (32 parts of tannin, 15 parts of modified furfuryl alcohol, and 3 parts of oxidized polyvinyl alcohol, with a weight ratio of 1:0.47:0.09, close to the range of 1:0.3-0.6:0.1-0.2), 20 parts of phosphorus-nitrogen synergistic flame retardant component (12 parts of phosphorus-containing intumescent flame retardant DDPPU and 8 parts of nitrogen-based flame retardant melamine cyanurate, with a weight ratio of 1.5:1, conforming to the range of 2:1-1.5), 8 parts of waterproof modification component (4 parts of silane coupling agent KH-560 and 4 parts of phytic acid, with a weight ratio of 1:1, conforming to the range of 1:0.8-1.2), and 4 parts of crosslinking aid (cationic polyacrylamide, number average molecular weight 3.0×10⁻⁶). 6 g / mol), 2 parts stabilizer (disodium ethylenediaminetetraacetate), 15 parts deionized water, and 5 parts filler (diatomaceous earth, 1500 mesh, pretreated with silane coupling agent KH-560).

[0026] Among them, the tannin is black thorn tannin with a number average molecular weight of 1800 g / mol; the modified furfuryl alcohol is modified furfuryl alcohol with polyethylene glycol monomethyl ether (number average molecular weight 600 g / mol), and the modification amount is 12% of the mass of furfuryl alcohol; the oxidation degree of oxidized polyvinyl alcohol is 28%, and the number average molecular weight is 4.0 × 10⁻⁶. 4 g / mol; phytic acid mass fraction 75%.

[0027] 2. Preparation method: (1) Weigh all components by weight, add 32 parts of tannin and 15 parts of deionized water from the formaldehyde-free matrix component to the reactor, stir at 350 r / min for 20 min at room temperature (25℃) until the tannin is completely dissolved and there is no obvious precipitate; (2) Add 15 parts of modified furfuryl alcohol and 2 parts of stabilizer to the reaction vessel, heat to 55°C, stir for 35 min, and obtain a uniform and transparent formaldehyde-free matrix solution. (3) Add 12 parts of DDPPU, 8 parts of melamine cyanurate, 4 parts of KH-560, 4 parts of phytic acid and 4 parts of cationic polyacrylamide to the formaldehyde-free matrix solution in sequence, keep the temperature at 55℃ and stir for 75 min to form a uniformly dispersed and non-layered mixed system. (4) Add 5 parts of pretreated diatomaceous earth to the above mixture system, continue stirring for 25 minutes, cool to room temperature (25℃), filter with a 200 mesh screen to remove a small amount of impurities, and obtain a light yellow, viscous formaldehyde-free waterproof flame retardant adhesive.

[0028] 3. Performance Testing: Formaldehyde release: 0.012 mg / m³ 3 (≤0.02mg / m 3 It has a 24-hour water absorption rate of 6.3% (≤8%), a limiting oxygen index of 35% (≥32%), and a bonding strength of 1.8MPa (≥1.5MPa). It meets the GB / T9846-2015 and GB8624-2012 B1 flame retardant standards, has no harmful gas emissions, and the preparation process is stable.

[0029] Example 2 (different component dosages, deviating from the preferred embodiment but within the scope of claim 1) 1. Components and weight parts: 40 parts of formaldehyde-free matrix component (25 parts tannin, 12 parts modified furfuryl alcohol, 3 parts oxidized polyvinyl alcohol, weight ratio 1:0.48:0.12), 15 parts of phosphorus-nitrogen synergistic flame retardant component (10 parts phosphorus-containing intumescent flame retardant DOPCP, 5 parts nitrogen-based flame retardant melamine phosphate, weight ratio 2:1), 5 parts of waterproof modification component (2.8 parts silane coupling agent KH-550, 2.2 parts phytic acid, weight ratio 1:0.79, close to the range of 1:0.8-1.2), 2 parts of crosslinking aid (carboxylated polyacrylamide, number average molecular weight 2.5×10⁻⁶). 6 g / mol), 1 part stabilizer (sodium citrate), 10 parts deionized water, and 3 parts filler (kaolin, 1000 mesh, pretreated with KH-550).

[0030] Among them, the tannin is larch tannin with a number-average molecular weight of 1200 g / mol; the modified furfuryl alcohol is modified furfuryl alcohol with polyethylene glycol monomethyl ether (number-average molecular weight of 400 g / mol), and the modification amount is 8% of the mass of furfuryl alcohol; the oxidation degree of oxidized polyvinyl alcohol is 20%, and the number-average molecular weight is 3.0 × 10⁻⁶.4 g / mol; phytic acid mass fraction 70%.

[0031] 2. Preparation method: (1) Add 25 parts of tannin and 10 parts of deionized water to the reactor and stir at 300 r / min for 15 min at room temperature (22℃) until the tannin is completely dissolved; (2) Add 12 parts of modified furfuryl alcohol and 1 part of stabilizer, heat to 50°C, stir for 30 min to obtain an aldehyde-free matrix solution; (3) Add 10 parts DOPCP, 5 parts melamine phosphate, 2.8 parts KH-550, 2.2 parts phytic acid, and 2 parts carboxylated polyacrylamide in sequence, keep at 50°C, stir for 60 min to form a mixed system; (4) Add 3 parts of pretreated kaolin, stir for 20 minutes, cool to room temperature, filter, and obtain formaldehyde-free waterproof flame retardant adhesive.

[0032] 3. Performance test: Formaldehyde emission 0.018 mg / m³ 3 The 24-hour water absorption rate is 7.8%, the limiting oxygen index is 32%, and the bonding strength is 1.5 MPa, all of which meet the performance indicators of claim 1 and the corresponding national standards.

[0033] Example 3 (different component dosages, deviating from the preferred embodiment but within the scope of claim 1) 1. Components and weight parts: 60 parts of formaldehyde-free matrix component (38 parts of tannin, 18 parts of modified furfuryl alcohol, and 4 parts of oxidized polyvinyl alcohol, weight ratio 1:0.47:0.11), 25 parts of phosphorus-nitrogen synergistic flame retardant component (15 parts of phosphorus-containing intumescent flame retardant DDPPU and 10 parts of nitrogen-based flame retardant melamine cyanurate, weight ratio 1.5:1), 12 parts of waterproof modification component (5.5 parts of silane coupling agent KH-560 and 6.5 parts of phytic acid, weight ratio 1:1.18, within the range of 1:0.8-1.2), and 6 parts of crosslinking aid (cationic polyacrylamide, number average molecular weight 3.5×10⁻⁶). 6 g / mol), 3 parts stabilizer (disodium ethylenediaminetetraacetate), 20 parts deionized water, and 8 parts filler (calcium carbonate, 2000 mesh, pretreated with KH-560).

[0034] Among them, the tannin is black thorn tannin with a number average molecular weight of 2500 g / mol; the modified furfuryl alcohol is modified furfuryl alcohol with polyethylene glycol monomethyl ether (number average molecular weight of 1000 g / mol), and the modification amount is 15% of the mass of furfuryl alcohol; the oxidation degree of oxidized polyvinyl alcohol is 35%, and the number average molecular weight is 5.0 × 10⁻⁶. 4 g / mol; phytic acid mass fraction 80%.

[0035] 2. Preparation method: (1) Add 38 parts of tannin and 20 parts of deionized water to the reactor and stir at 500 r / min for 25 min at room temperature (28℃) until the tannin is completely dissolved; (2) Add 18 parts of modified furfuryl alcohol and 3 parts of stabilizer, heat to 60°C, stir for 40 min to obtain an aldehyde-free matrix solution; (3) Add 15 parts of DDPPU, 10 parts of melamine cyanurate, 5.5 parts of KH-560, 6.5 parts of phytic acid and 6 parts of cationic polyacrylamide in sequence, keep at 60℃ and stir for 90 min to form a mixed system; (4) Add 8 parts of pretreated calcium carbonate, stir for 30 minutes, cool to room temperature, filter, and obtain formaldehyde-free waterproof flame retardant adhesive.

[0036] 3. Performance test: Formaldehyde emission 0.010 mg / m³ 3 It has a 24-hour water absorption rate of 5.7%, a limiting oxygen index of 38%, and a bonding strength of 2.1 MPa, which are better than the minimum performance indicators of claim 1. It also has superior flame retardant, waterproof and bonding properties.

[0037] Comparative Example 1 (lacking phosphorus-nitrogen synergistic flame retardant components, compared to Example 1) 1. Components and weight parts: 50 parts of formaldehyde-free matrix component (same as in Example 1), 8 parts of waterproof modification component (same as in Example 1), 4 parts of crosslinking aid (same as in Example 1), 2 parts of stabilizer (same as in Example 1), 15 parts of deionized water, 5 parts of filler (same as in Example 1), without phosphorus-nitrogen synergistic flame retardant component.

[0038] 2. Preparation method: Same as in Example 1, except that the step of adding phosphorus-nitrogen synergistic flame retardant components is omitted.

[0039] 3. Performance test: Formaldehyde emission 0.013 mg / m³ 3 (Meets formaldehyde-free requirements), 24-hour water absorption rate of 6.5% (meets waterproof requirements), limiting oxygen index of 26% (<32%, does not meet flame retardant requirements), and bonding strength of 1.7 MPa (meets bonding requirements), indicating that the phosphorus-nitrogen synergistic flame retardant component is the key to achieving the flame retardant performance of this invention.

[0040] Comparative Example 2 (using a strong acid catalyst, replacing phytic acid, compared to Example 1) 1. Components and weight parts: 50 parts of formaldehyde-free matrix component (same as in Example 1), 20 parts of phosphorus-nitrogen synergistic flame retardant component (same as in Example 1), 8 parts of waterproof modification component (4 parts of silane coupling agent KH-560, with 0.5 parts of concentrated sulfuric acid replacing 4 parts of phytic acid as catalyst), 4 parts of crosslinking aid (same as in Example 1), 2 parts of stabilizer (same as in Example 1), 15 parts of deionized water, and 5 parts of filler (same as in Example 1).

[0041] 2. Preparation method: Same as in Example 1, except that phytic acid is replaced with concentrated sulfuric acid.

[0042] 3. Performance test: Formaldehyde emission 0.012 mg / m³ 3 The 24-hour water absorption rate was 9.2% (>8%, not meeting waterproof requirements), the limiting oxygen index was 34% (meets flame retardant requirements), and the bonding strength was 1.4 MPa (<1.5 MPa, not meeting bonding requirements). Furthermore, the adhesive showed delamination and yellowing after 3 days of storage, indicating that the use of strong acid catalysts would lead to substrate degradation, decreased waterproofing and bonding performance. Phytic acid, as a mild acid catalyst, can effectively avoid this problem and at the same time help improve waterproofing performance.

[0043] Example Description: Examples 1-3 above all achieve the synergistic effects of formaldehyde-free, waterproof, and flame-retardant properties, and their performance meets the requirements of the claims of this invention. Among them, Example 1 (preferred solution) has the best overall performance. Comparative Examples 1-2 demonstrate that the phosphorus-nitrogen synergistic flame-retardant component and phytic acid (mild acid catalyst + waterproofing aid) of this invention are the core components for achieving key performance. Their absence or substitution will prevent the achievement of the technical effects of this invention, further demonstrating the inventiveness and practicality of this invention. The preparation process of all examples does not require high temperature and high pressure, has no harmful gas emissions, can be mass-produced, and is convenient, energy-saving, and environmentally friendly when applied to fields such as engineered wood products.

[0044] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A formaldehyde-free, waterproof, and flame-retardant adhesive formula, characterized in that: By weight, the formula comprises the following essential components: 40-60 parts of formaldehyde-free matrix component, 15-25 parts of phosphorus-nitrogen synergistic flame retardant component, 5-12 parts of waterproof modification component, 2-6 parts of crosslinking aid, 1-3 parts of stabilizer, and 10-20 parts of deionized water; the formula contains no formaldehyde-releasing components or strong acid catalysts, and the formaldehyde release is ≤0.02mg / m³. 3 The 24-hour water absorption rate is ≤8%, the limiting oxygen index is ≥32%, and the bonding strength is ≥1.5MPa, meeting the GB / T9846-2015 and GB8624-2012 B1 flame retardant standards.

2. The formaldehyde-free waterproof and flame-retardant adhesive formulation according to claim 1, characterized in that, The formaldehyde-free matrix component is a composite bio-based system, composed of tannins, modified furfuryl alcohol, and oxidized polyvinyl alcohol in a weight ratio of 1:0.3-0.6:0.1-0.

2. The tannins are selected from black thorn tannins or larch tannins, with a number-average molecular weight of 1200-2500 g / mol. The modified furfuryl alcohol is polyethylene glycol monomethyl ether modified furfuryl alcohol, with a number-average molecular weight of 400-1000 g / mol, and the modification amount is 8%-15% of the furfuryl alcohol mass. The oxidized polyvinyl alcohol has an oxidation degree of 20%-35% and a number-average molecular weight of 3.0 × 10⁻⁶. 4 -5.0×10 4 g / mol.

3. The formaldehyde-free waterproof and flame-retardant adhesive formulation according to claim 1, characterized in that, The phosphorus-nitrogen synergistic flame retardant component is a composite system, composed of a phosphorus-containing intumescent flame retardant and a nitrogen-based flame retardant at a weight ratio of 2:1-1.5; the phosphorus-containing intumescent flame retardant is selected from N,N-bis(2,2-dimethyl-1,3-propanediol phosphate)urea (DDPPU) or (1-oxo-1-phospha-2,6,7-trioxabicyclo(2.2.2)octane-4-carbonyl)neopentyl glycol ester (DOPCP); the nitrogen-based flame retardant is selected from one or two of melamine cyanurate and melamine phosphate in any proportion.

4. The formaldehyde-free waterproof and flame-retardant adhesive formulation according to claim 1, characterized in that, The waterproofing modified component includes a silane coupling agent and phytic acid, with a weight ratio of 1:0.8-1.2; the silane coupling agent is selected from KH-550 and KH-560; the phytic acid has a mass fraction of 70%-80%, serving as a mild acid catalyst and waterproofing auxiliary component to avoid substrate degradation caused by the migration of acidic components.

5. The formaldehyde-free waterproof and flame-retardant adhesive formulation according to claim 1, characterized in that, The crosslinking aid is selected from cationic polyacrylamide and carboxylated polyacrylamide, with a number average molecular weight of 2.5 × 10⁻⁶. 6 -3.5×10 6 g / mol; the stabilizer is selected from disodium ethylenediaminetetraacetate and sodium citrate, and is used to inhibit the runaway polymerization of furfuryl alcohol and component stratification.

6. The formaldehyde-free waterproof and flame-retardant adhesive formulation according to claim 1, characterized in that, It also includes 3-8 parts of filler, which is selected from one or more of diatomaceous earth, kaolin, and calcium carbonate and mixed in any proportion. The filler particle size is 1000-2000 mesh. It is added after pretreatment with silane coupling agent to improve the mechanical strength and water resistance of the adhesive.

7. The formaldehyde-free waterproof and flame-retardant adhesive formulation according to claim 1, characterized in that, The preferred weight proportions of each component are: 50 parts of formaldehyde-free matrix component, 20 parts of phosphorus-nitrogen synergistic flame retardant component, 8 parts of waterproof modification component, 4 parts of crosslinking aid, 2 parts of stabilizer, 15 parts of deionized water, and 5 parts of filler.

8. The method for preparing the formaldehyde-free waterproof and flame-retardant adhesive formulation according to any one of claims 1-7, characterized in that, Includes the following steps: (1) Weigh all components by weight, add tannin and deionized water from the formaldehyde-free matrix component to the reactor, and stir at 300-500 r / min for 15-25 min at room temperature until the tannin is completely dissolved. (2) Add modified furfuryl alcohol and stabilizer to the reaction vessel, heat to 50-60℃, stir for 30-40 min to obtain aldehyde-free matrix solution; (3) Add the phosphorus-nitrogen synergistic flame retardant component, waterproof modification component and crosslinking aid to the formaldehyde-free matrix solution in sequence, keep the temperature at 50-60℃ and stir for 60-90min to form a uniformly dispersed mixed system; (4) If filler is added, the pretreated filler is added to the above mixing system, and stirring is continued for 20-30 minutes. The mixture is then cooled to room temperature, filtered to remove impurities, and formaldehyde-free waterproof and flame-retardant adhesive is obtained. The entire preparation process does not require high temperature and high pressure, and there is no harmful gas emission, which can realize large-scale production.

9. The application of the formaldehyde-free waterproof and flame-retardant adhesive formulation according to any one of claims 1-7, characterized in that, The adhesive is used in the fields of artificial boards (plywood, particleboard, fiberboard), furniture manufacturing, building decoration, and packaging materials. It can be applied using cold pressing or hot pressing processes. The cold pressing temperature is 20-40℃, and the hot pressing temperature is 100-120℃. The application is convenient, energy-saving, and environmentally friendly.

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