Biomass recoverable flame-retardant binder as well as preparation method and application thereof

Abstract

The invention belongs to the field of binders, and particularly relates to a flame-retardant binder as well as a preparation method and application thereof. The preparation method of the flame-retardant binder comprises the following steps: uniformly stirring and mixing a biomass raw material and a solvent to obtain a biomass solution; uniformly stirring and mixing a cross-linking agent and the biomass solution to obtain a precursor solution with the solid content of 5-50wt%; and adjusting the pH value of the precursor solution to 3-5 to prepare the flame-retardant binder. According to the invention, the biomass raw material and the cross-linking agent are taken as raw materials, the construction of a cross-linked network is realized by taking pH as driving force, and the bio-based adhesive with the advantages of high adhesive property, high flame retardant property, recoverability, environment friendliness and the like is prepared by controlling the solid content of a precursor solution and the pH of a system; the method can be applied to preparation of products such as a multilayer plate composite material, a particle plate composite material, a coating composite material and a flame-retardant film, and has wide practical application.

Description

Technical Field

[0001] The present invention belongs to the field of adhesives, and particularly relates to a flame-retardant adhesive, a preparation method thereof, and an application thereof. Background Art

[0002] Adhesives, as indispensable functional materials in the modern industrial field, are widely used in many key fields such as construction, furniture manufacturing, packaging industry, automobile manufacturing, electronics industry, and aerospace. With the continuous acceleration of the global industrialization process, the demand in the adhesive market shows a continuous growth trend. According to the data predicted by Globe Newswire in 2023, from 2022 to 2030, the compound annual growth rate (CAGR) of the global adhesive market is expected to reach 4.9%. By 2030, the scale of this market is expected to exceed the $63.9 billion mark. This growth momentum mainly comes from the increase in building renovation projects, the booming development of new energy vehicle manufacturing, and the rapid rise of the green packaging industry.

[0003] However, behind the market prosperity, there are also severe resource, environmental, and health challenges. Currently, among the commonly used adhesives on the market, more than 90% of the raw materials are derived from petroleum resources, and these adhesives often contain a variety of organic solvents, and some even contain aldehyde resin components. During the manufacturing process and use process, these adhesives will continuously release harmful formaldehyde and volatile organic compounds (VOCs), posing a major threat to the environment and human health. In addition, due to the interaction of these adhesives with the substrate through covalent bonds, their permanent characteristics make them extremely difficult to be effectively removed and recycled from the substrate. A large number of waste adhesives and their bonded products are ultimately disposed of through rough methods such as landfilling and incineration, which undoubtedly further exacerbates the environmental burden.

[0004] In this context, bio-based adhesives have attracted much attention from the industry due to their unique characteristics of renewable raw materials, degradability, and environmental friendliness. Facing the multiple trends of increasingly tight petroleum resource constraints and the transformation of the circular economy, the demand for developing recyclable and environmentally friendly bio-based adhesives to replace traditional petroleum-based adhesives is particularly urgent.

[0005] In addition, as a functional interface material, the application scenarios of modern adhesives have evolved from single bonding requirements to multi-functional integration. In typical application scenarios such as building curtain wall systems, furniture composite boards, new energy vehicle battery pack encapsulation, and high-density electronic device integration, the flame retardant performance of the bonding material directly determines the fire response level and safety of the overall structure. However, bio-based adhesives tend to be highly flammable. In specific usage environments such as high temperatures, once exposed to a fire source, they are extremely likely to trigger large-scale fires, posing a potential fire threat to life and property safety.

[0006] Therefore, the development of a biomass recyclable flame retardant adhesive not only has important scientific value but also broad application prospects and practical significance. This will provide a practical path to address the resource, environmental, and health challenges faced by the current adhesive market. Summary of the Invention

[0007] To solve the above problems, the present invention provides a flame retardant adhesive, its preparation method, and its application.

[0008] In the first aspect, the present invention provides a preparation method of a flame retardant adhesive, and the preparation method includes the following steps:

[0009] Stir and mix the biomass raw material and the solvent to obtain a biomass solution;

[0010] Stir and mix the crosslinking agent and the biomass solution to obtain a precursor solution with a solid content of 5 - 50 wt%;

[0011] Adjust the pH of the precursor solution to 3 - 5 to obtain the flame retardant adhesive;

[0012] Wherein, the crosslinking agent is selected from at least one of: silane coupling agent, phosphorus-containing compound with an acid root ion or a hydroxyl group, or phosphate with an acid root ion or a hydroxyl group.

[0013] Further, the mass ratio of the biomass raw material to the crosslinking agent is 10:(0.5 - 10), preferably 10:(2 - 8); the solid content of the adhesive precursor solution is 10 - 30 wt%.

[0014] Further, the biomass raw material is selected from at least one of biomass containing a hydroxyl group and biomass containing an amino group.

[0015] Furthermore, the biomass raw material is at least one of konjac gum, gelatin, gellan gum, chitosan, or peach gum.

[0016] Further, among the above crosslinking agents, the phosphoric acid compound or phosphate containing an acid radical ion or a hydroxyl group is: ammonium polyphosphate (abbreviated as APP in English), phosphoric acid, or diphosphorus dihydroxymethyl oxide (abbreviated as THPO in English).

[0017] Further, among the above crosslinking agents, the silane coupling agent is: silane coupling agent KH550 (abbreviated as KH550), silane coupling agent KH570 (abbreviated as KH570).

[0018] Further, the solvent is water.

[0019] Further, the working condition parameters of the stirring and mixing include: the temperature is from room temperature to 120 °C, preferably 50 - 100 °C.

[0020] Further, the pH adjustment method includes dropping acetic acid, phosphoric acid, or dilute sulfuric acid into the binder precursor solution.

[0021] In a second aspect, the present invention provides a flame - retardant binder, which is prepared by using the preparation method of the binder according to any one of the first aspect.

[0022] Further, the physicochemical property parameters of the binder include: the bonding strength is 5 Mpa - 65 Mpa, the limiting oxygen index is 23% - 40%, and the peak heat release is 50 kW / m 2 ~312 kW / m 2 .

[0023] In a third aspect, the present invention provides an application of the binder according to any one of the second aspect in the preparation of multilayer board composites, particle board composites, coating composites, or flame - retardant films.

[0024] In a fourth aspect, the present invention provides a multilayer board composite, which is prepared by bonding wooden boards with the binder according to any one of the second aspect and then processing and forming.

[0025] Further, the usage amount of the binder accounts for 1 - 20 wt% of the weight of the wooden board.

[0026] Further, the wooden board includes at least one of pine wood board, fir wood board, poplar wood board, oak wood board, teak wood board, elm wood board, maple wood board, and birch wood board.

[0027] Further, the processing and forming method includes at least one of molding, hot - pressing forming, or thermosetting forming.

[0028] In a fifth aspect, the present invention provides a particle board composite, which is prepared by bonding wood chips with the binder according to any one of the second aspect and then processing and forming.

[0029] Furthermore, the usage amount of the binder accounts for 5-20 wt% of the weight of the wood chips particles.

[0030] Furthermore, the wood chips particles include at least one of pine wood chips particles, fir wood chips particles, poplar wood chips particles, oak wood chips particles, teak wood chips particles, elm wood chips particles, maple wood chips particles and birch wood chips particles.

[0031] Furthermore, the processing and forming method includes at least one of molding, hot pressing and thermosetting.

[0032] In a sixth aspect, the present invention provides a composite material. The coated composite material includes a matrix material and a modified layer. The modified layer is a coating or film layer formed by attaching the binder according to any one of the second aspect on the surface of the matrix material.

[0033] Among them, the matrix material includes at least one of a wood matrix material, a foam matrix material and a fabric matrix material. The wood matrix material includes at least one of pine, fir, poplar, oak, teak, elm, maple and birch. The foam matrix material includes at least one of polyurethane foam, polystyrene foam, polypropylene foam and polyimide foam. The fabric matrix material includes at least one of cotton fabric, linen fabric, silk fabric, wool fabric, polyester fabric, acrylic fabric, spandex fabric, nylon fabric and blended fabric.

[0034] Furthermore, the coating method for preparing the coating includes at least one of brushing, scraping, spraying and sputtering.

[0035] Furthermore, the method for preparing the film layer includes: 1) Pour the binder according to any one of the second aspect onto a non-polar polytetrafluoroethylene plate and air-dry it at 25 °C for 24 h to obtain a film layer (a water-to-binder transparent flame-retardant film); 2) Wet the transparent flame-retardant film and attach it to the surface of the matrix material to obtain it.

[0036] In a seventh aspect, the present invention provides a flame-retardant film. The flame-retardant film is prepared by using the binder according to any one of the second aspect, such as by air-drying at room temperature.

[0037] Furthermore, the method for preparing the flame-retardant film includes: Pour the binder according to any one of the second aspect onto a non-polar polytetrafluoroethylene plate and air-dry it at 25 °C for 24 h to obtain it.

[0038] The present invention has at least the following advantages compared with the prior art:

[0039] The present invention provides an adhesive and its preparation method and application. The present invention forms a three-dimensional cross-linked network through the physicochemical interaction between a bio-based material and a cross-linking agent, and further adjusts the three-dimensional cross-linked network structure with pH as the driving force to enhance the cohesion, thereby obtaining a recyclable and environmentally friendly bio-based flame-retardant adhesive, achieving the balance between the cohesion and interfacial adhesion of the bio-based adhesive, and further improving its bonding strength; various composite materials prepared from this bio-based adhesive have recyclability, higher mechanical properties, and excellent flame-retardant properties; this method introduces a cross-linking agent with flame-retardant potential in a way that increases cohesion, solves the problem that it is difficult for bio-based adhesives to coordinate flame-retardant properties and bonding properties, has various application methods, prominent flame-retardant effects, and the advantage of being reusable, and has practical application value.

[0040] Specifically, after bonding multi-layer boards and wood chips particles and being processed and formed, this bio-based flame-retardant adhesive can be used to prepare multi-layer board composite materials and particle board composite materials. Thanks to the excellent cohesion and bonding performance of the adhesive, the prepared multi-layer board composite materials and particle board composite materials exhibit stronger mechanical properties. These composite materials are not only structurally strong but also can maintain good integrity when subjected to external forces, meeting the high requirements for the mechanical properties of materials in various application scenarios.

[0041] More importantly, the multi-layer board composite materials and particle board composite materials prepared by the present invention also have excellent flame-retardant properties. This benefits from the flame-retardant components and special cross-linked network structure in the bio-based flame-retardant adhesive, which can effectively prevent the spread of flames, reduce the risk of fire occurrence, and provide strong protection for people's lives and property safety.

[0042] In addition, the recyclable and environmentally friendly bio-based flame-retardant adhesive of the present invention also has good recyclability. This means that during use or after being discarded, this adhesive can be recycled through appropriate recycling processes, realizing the reuse of resources, reducing environmental pollution and waste of resources.

[0043] It is worth mentioning that when the bio-based flame-retardant adhesive and its self-supporting film of the present invention are used as coatings, they also exhibit high transparency. This high transparency not only enables the coated substrate material to maintain its original aesthetics but also has no negative impact on the visual effect of the substrate material. At the same time, the adhesive has excellent adhesion to the substrate material, can firmly adhere to the substrate surface, form a dense fireproof and flame-retardant protective layer, and provide long-term fireproof and flame-retardant protection for the substrate material.

[0044] In summary, the recyclable, environmentally friendly bio-based flame retardant binder, its composite materials and applications of the present invention not only have excellent mechanical properties and flame retardant properties, but also have good recyclability, environmental friendliness, high transparency and excellent adhesion, providing new ideas and directions for the development of the binder field. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The drawings herein are incorporated into and constitute a part of this specification, showing embodiments in accordance with the present invention and, together with the specification, are used to explain the principles of the present invention.

[0046] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or in the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0047] Figure 1 It is a schematic flow chart of a preparation method of a binder provided by the present invention.

[0048] Figure 2 It is a digital photo of the stratification of the mixed solution in Comparative Example 5 of the present invention.

[0049] Figure 3 It is a digital photo of the bonding failure in Comparative Example 7 of the present invention.

[0050] Figure 4 It is a diagram of the macroscopic morphology, microscopic morphology and flame retardant performance test results of the composite materials obtained in Application Examples 1 to 4 of the present invention; among them, Figure 4 wherein: a, a2 and a3 are respectively the macroscopic photo, microscopic structure and flame retardant performance of the coated foam in Application Example 1; b, b2 and b3 are respectively the macroscopic photo, microscopic structure and flame retardant performance of the multilayer board prepared in Application Example 2; c, c2 and c3 are respectively the macroscopic photo, microscopic structure and flame retardant performance of the flame retardant film prepared in Application Example 3; d, d2 and d3 are respectively the macroscopic photo, microscopic structure and flame retardant performance of the particle board prepared in Application Example 4.

[0051] Figure 5 It is a diagram of the recycling process and the performance test results after recycling of the water-to-bond transparent flame retardant film and particle board composite materials obtained in Application Examples 5 and 6 of the present invention; among them, Figure 5 wherein: a and a2 are the performance test results of the materials before and after the film recycling in Application Example 5; b and b2 are the performance test results of the materials before and after the recycling of the flame retardant particle board in Application Example 6. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0052] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0053] Unless otherwise specifically stated, all kinds of raw materials, reagents, instruments, and equipment used in the present invention can be obtained through market purchases or can be prepared by existing methods.

[0054] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. The experimental methods without specific conditions noted in the following embodiments are usually determined according to national standards. If there is no corresponding national standard, they are carried out according to general international standards, conventional conditions, or conditions recommended by the manufacturer.

[0055] Example 1

[0056] This example provides an adhesive, and its preparation method includes the following steps:

[0057] Weigh 25 g of gelatin, add 75 g of deionized water thereto, place it in a water bath at 60 °C, heat and stir for 30 min until it becomes clear and transparent to obtain a gelatin solution with a solid content of 25 wt%, and set it aside; additionally, weigh 15 g of ammonium polyphosphate, add 45 g of deionized water thereto, and then ultrasonically emulsify until it becomes clear and transparent to obtain an ammonium polyphosphate solution with a solid content of 25 wt%, and set it aside; mix 100 g of the gelatin solution with 60 g of the ammonium polyphosphate solution (the solid content in the mixed solution is 25%), place it in a water bath at 60 °C, heat and stir for 30 min to prepare a precursor solution, during which the pH change of the solution is detected, and after its value stabilizes, adjust the pH of the solution to 5 with glacial acetic acid to obtain a recyclable and environmentally friendly bio-based flame-retardant adhesive.

[0058] The shear bond strength of this adhesive is 18 MPa, the limiting oxygen index is 32%, and the peak heat release is 163 kW / m 2 .

[0059] Example 2

[0060] This example provides an adhesive, and its preparation method includes the following steps:

[0061] Weigh 16.7 g of gelatin, add 83.3 g of deionized water to it, place it in a water bath at 60 °C, heat and stir for 30 min until a clear and transparent solution is obtained, to obtain a gelatin solution with a solid content of 16.7 wt%, for later use; add 8.3 g of silane coupling agent KH550 to 100 g of the gelatin solution, place it in a water bath at 85 °C, heat and react for 30 min to prepare a precursor solution (solid content is 25 wt%), during which the pH change of the solution is detected, and after its value is stable, adjust the pH of the solution to 3 with acetic acid solution, then a recyclable and environmentally friendly bio-based flame retardant binder can be obtained.

[0062] The shear bond strength of this binder is 12.6 MPa, the limiting oxygen index is 23%, and the peak heat release is 312 kW / m 2 。

[0063] Example 3

[0064] This example provides a binder, and its preparation method includes the following steps:

[0065] Weigh 16.7 g of gelatin, add 83.3 g of deionized water to it, place it in a water bath at 60 °C, heat and stir for 30 min until a clear and transparent solution is obtained, to obtain a gelatin solution with a solid content of 16.7 wt%, for later use; add 4.15 g of silane coupling agent KH550 and 4.15 g of ammonium polyphosphate to 100 g of the gelatin solution, place it in a water bath at 85 °C, heat and react for 30 min to prepare a precursor solution, during which the pH change of the solution is detected, and after its value is stable, adjust the pH of the solution to 3 with acetic acid solution, then a recyclable and environmentally friendly bio-based flame retardant binder can be obtained.

[0066] The shear bond strength of this binder is 42 MPa, the limiting oxygen index is 40%, and the peak heat release is 152 kW / m 2 。

[0067] Example 4

[0068] This example provides a binder, and its preparation method includes the following steps:

[0069] Weigh 13.4 g of peach gum, add 76.7 g of deionized water to it, place it in a water bath at 60 °C, heat and stir for 30 min until a clear and transparent solution is obtained, for later use; then add 3.3 g of phytic acid (equivalent to adding 6.6 g of phytic acid aqueous solution with a solid content of 50%) and 3.3 g of silane coupling agent KH570, place it in a water bath at 85 °C, heat and react for 30 min to prepare a precursor solution, during which the pH change of the solution is detected, and after its value is stable, adjust the pH of the solution to 5 with acetic acid solution, then a recyclable and environmentally friendly bio-based flame retardant binder can be obtained.

[0070] The shear bond strength of this binder is 28.6 MPa, the limiting oxygen index is 34%, and the peak heat release is 210 kW / m 2 。

[0071] Example 5

[0072] This example provides an adhesive, and its preparation method includes the following steps:

[0073] Weigh 5 g of gellan gum, add 85 g of deionized water to it, place it in a water bath at 60 °C, heat and stir for 30 min until a clear and transparent solution is obtained. Then add 5 g of phytic acid (equivalent to adding 10 g of an aqueous phytic acid solution with a solid content of 50%), place it in a water bath at 85 °C, heat and react for 30 min to obtain a precursor solution. During this period, the pH change of the solution is detected. After its value is stable, the pH of the solution is adjusted to 5 with acetic acid solution, and a recyclable and environmentally friendly bio-based flame-retardant adhesive can be obtained.

[0074] The shear bond strength of this adhesive is 7.6 MPa, the limiting oxygen index is 28%, and the peak heat release is 246 kW / m 2 .

[0075] Example 6

[0076] This example provides an adhesive, and its preparation method includes the following steps:

[0077] Weigh 17.5 g of konjac gum, add 70 g of deionized water to it, place it in a water bath at 60 °C, heat and stir for 30 min until a clear and transparent solution is obtained. Then add 6.25 g of THPO (trimethylolphosphine oxide) and 6.25 g of KH550, place it in a water bath at 85 °C, heat and react for 30 min to obtain a precursor solution. During this period, the pH change of the solution is detected. After its value is stable, the pH of the solution is adjusted to 5 with acetic acid solution, and a recyclable and environmentally friendly bio-based flame-retardant adhesive can be obtained.

[0078] The shear bond strength of this adhesive is 56 MPa, the limiting oxygen index is 31%, and the peak heat release is 113 kW / m 2 .

[0079] Example 7

[0080] This example provides an adhesive, and its preparation method includes the following steps:

[0081] Weigh 14 g of konjac gum, add 64 g of deionized water to it, place it in a water bath at 60 °C, heat and stir for 30 min until a clear and transparent solution is obtained. Then add 6 g of phytic acid (equivalent to adding 12 g of an aqueous phytic acid solution with a solid content of 50%) and 10 g of KH550, place it in a water bath at 85 °C, heat and react for 30 min to obtain a precursor solution. During this period, the pH change of the solution is detected. After its value is stable, the pH of the solution is adjusted to 5 with acetic acid solution, and a recyclable and environmentally friendly bio-based flame-retardant adhesive can be obtained.

[0082] The shear bond strength of this binder is 65 MPa, the limiting oxygen index is 36%, and the peak heat release is 90 kW / m 2 .

[0083] Comparative Example 1

[0084] Weigh 25 g of gelatin, add 75 g of deionized water to it, place it in a water bath at 60 °C, heat and stir for 30 min until it becomes clear and transparent, obtain a gelatin solution with a solid content of 25 wt%, and adjust the pH of the solution to 5 with glacial acetic acid to obtain the product. Use pine wood to test its bond strength and flame retardancy performance.

[0085] The shear bond strength of the obtained product is 3.5 MPa, the limiting oxygen index is 20%, and the peak heat release is 320 kW / m 2 .

[0086] Comparative Example 2

[0087] Weigh 20 g of peach gum, add 80 g of deionized water to it, place it in a water bath at 60 °C, heat and stir for 30 min until it becomes clear and transparent, obtain a peach gum solution with a solid content of 20 wt%, and adjust the pH of the solution to 5 with glacial acetic acid to obtain the product. Use pine wood to test its bond strength and flame retardancy performance.

[0088] The shear bond strength of the obtained product is 1.5 MPa, the limiting oxygen index is 18%, and the peak heat release is 368 kW / m 2 .

[0089] Comparative Example 3

[0090] Weigh 20 g of gellan gum, add 80 g of deionized water to it, place it in a water bath at 60 °C, heat and stir for 30 min until it becomes clear and transparent, obtain a gellan gum solution with a solid content of 20 wt%, and adjust the pH of the solution to 5 with glacial acetic acid to obtain the product. Use pine wood to test its bond strength and flame retardancy performance.

[0091] The shear bond strength of the obtained product is 0.8 MPa, the limiting oxygen index is 19%, and the peak heat release is 343 kW / m 2 .

[0092] Comparative Example 4

[0093] Weigh 2.5 g of gelatin, add 60 g of deionized water to it, place it in a water bath at 60 °C, heat and stir for 30 min until it becomes clear and transparent, obtaining a gelatin solution with a solid content of 4 wt%, for later use; additionally, weigh 1.5 g of ammonium polyphosphate, add 37.5 g of deionized water to it, and then ultrasonically emulsify until it becomes clear and transparent, obtaining an ammonium polyphosphate solution with a solid content of 4 wt%, for later use; mix 62.5 g of the gelatin solution and 39 g of the ammonium polyphosphate solution, place it in a water bath at 60 °C, heat and stir for 30 min, during which the pH change of the solution is detected, and after its value stabilizes, adjust the pH of the solution to 5 with glacial acetic acid to obtain the product.

[0094] The shear bond strength of the obtained product is 0.8 MPa, the limiting oxygen index is 23%, and the peak heat release is 278 kW / m 2 。

[0095] Comparative Example 5

[0096] Weigh 15.6 g of gelatin, add 46.8 g of deionized water to it, place it in a water bath at 60 °C, heat and stir for 30 min until it becomes clear and transparent, obtaining a gelatin solution with a solid content of 25 wt%, for later use; additionally, weigh 9.4 g of ammonium polyphosphate, add 28.2 g of deionized water to it, and then ultrasonically emulsify until it becomes clear and transparent, obtaining an ammonium polyphosphate solution with a solid content of 10 wt%, for later use; mix 62.4 g of the gelatin solution and 37.6 g of the ammonium polyphosphate solution, place it in a water bath at 60 °C, heat and stir for 30 min, during which the pH change of the solution is detected, and after its value stabilizes, adjust the pH of the solution to 11 with sodium hydroxide solution.

[0097] The solution is layered and the bonding performance of the solution fails.

[0098] Comparative Example 6

[0099] Weigh 2 g of peach gum, add 95 g of deionized water to it, place it in a water bath at 60 °C, heat and stir for 30 min until it becomes a clear and transparent solution; then add 1 g of phytic acid (equivalent to adding 2 g of an aqueous phytic acid solution with a solid content of 50%) and 1 g of silane coupling agent KH570, place it in a water bath at 85 °C, heat and react for 30 min, during which the pH change of the solution is detected, and after its value stabilizes, adjust the pH of the solution to 4 with acetic acid solution to prepare the product.

[0100] The shear bond strength of the obtained product is 1.6 MPa, the limiting oxygen index is 26%, and the peak heat release is 280 kW / m 2 。

[0101] Comparative Example 7

[0102] Weigh 10 g of peach gum, add 75 g of deionized water to it, place it in a water bath at 60 °C, heat and stir for 30 min until a clear and transparent solution is obtained; then add 5 g of phytic acid (equivalent to adding 10 g of an aqueous phytic acid solution with a solid content of 50%) and 5 g of silane coupling agent KH570, place it in a water bath at 85 °C, heat and react for 30 min, during which the pH change of the solution is detected, and after its value is stable, adjust the pH of the solution to 1 with acetic acid solution.

[0103] The bonding performance of the solution fails.

[0104] Comparative Example 8

[0105] Weigh 10 g of peach gum, add 75 g of deionized water to it, place it in a water bath at 60 °C, heat and stir for 30 min until a clear and transparent solution is obtained, then add 5 g of phytic acid (equivalent to adding 10 g of an aqueous phytic acid solution with a solid content of 50%) and 5 g of silane coupling agent KH570, place it in a water bath at 85 °C, heat and react for 30 min, without adjusting the pH value.

[0106] The shear bond strength of the obtained product is 0.8 MPa, the limiting oxygen index is 32%, and the peak heat release is 223 kW / m 2 .

[0107] Application Example 1

[0108] Select rigid polyurethane foam (RPUF) as the matrix material of the coated composite material, with the ratio of bio-based raw material: cross-linking agent = 5:3. The weight gain of the prepared coated composite material is 10 wt%. The specific preparation method is as follows:

[0109] 1) Preparation of the flame retardant binder: Weigh 25 g of gelatin, add 75 g of deionized water to it, place it in a water bath at 60 °C, heat and stir for 30 min until it is clear and transparent to obtain a gelatin solution with a solid content of 25 wt%, for later use; separately weigh 15 g of ammonium polyphosphate, add 45 g of deionized water to it, and then ultrasonically emulsify until it is clear and transparent to obtain an ammonium polyphosphate solution with a solid content of 25 wt%, for later use; mix 100 g of the gelatin solution and 60 g of the ammonium polyphosphate solution (the solid content in the mixed solution is 10%), place it in a water bath at 60 °C, heat and stir for 30 min, during which the pH change of the solution is detected, and after its value is stable, adjust the pH of the solution to 4 - 5 with glacial acetic acid to obtain a recyclable and environmentally friendly bio-based flame retardant binder.

[0110] 2) Preparation of the coated composite material: Brush the above solution evenly on the surface of RPUF, control the weight gain of RPUF to be 10 wt%, then place it in an oven at 25 °C for curing and drying for 4 h, and then place it in an oven at 80 °C for drying for 4 h to obtain a coated composite material with a weight gain of 10 wt%.

[0111] The limiting oxygen index of the composite material is 36%, and the peak heat release is 146 kW / m2 。

[0112] Application Example 2

[0113] Select basswood board as the matrix material of the multi-layer board composite material, with the ratio of bio-based raw material: cross-linking agent = 5:3. The weight gain of the prepared multi-layer board composite material is 1.5 wt%, and the specific preparation method is as follows:

[0114] 1) Preparation of the flame retardant binder: Weigh 25 g of gelatin, add 75 g of deionized water thereto, place it in a water bath at 60 °C, heat and stir for 30 min until it becomes clear and transparent to obtain a gelatin solution with a solid content of 25 wt%, for later use; additionally weigh 15 g of ammonium polyphosphate, add 45 g of deionized water thereto, and then ultrasonically emulsify until it becomes clear and transparent to obtain an ammonium polyphosphate solution with a solid content of 25 wt%, for later use; mix 100 g of the gelatin solution and 60 g of the ammonium polyphosphate solution (the solid content in the mixed solution is 10%), place it in a water bath at 60 °C, heat and stir for 30 min, during which the pH change of the solution is detected. After its value stabilizes, adjust the pH of the solution to 4 - 5 with glacial acetic acid to obtain a recyclable and environmentally friendly bio-based flame retardant binder.

[0115] 2) Preparation of the coated composite material: Brush the solution evenly on the surface of each layer of basswood board, control the ratio of the total coating amount to the mass of the basswood board to be 6.6:1, bond multiple single-layer basswood boards brushed with GA together, and then place them in an oven at 80 °C for curing and drying for 4 h to obtain the multi-layer board composite material.

[0116] The limiting oxygen index of the composite material is 35%, and the peak heat release is 112 kW / m 2 。

[0117] Application Example 3

[0118] Select pine board as the matrix material of the coated composite material, and use a thin film to adhere to the wood surface to endow the material with flame retardant properties. Among them, the ratio of bio-based raw material: cross-linking agent = 5:3. The weight gain of the prepared coated composite material is 1.5 wt%, and the specific preparation method is as follows:

[0119] 1) Preparation of the flame retardant binder: Weigh 25 g of gelatin, add 75 g of deionized water thereto, place it in a water bath at 60 °C, heat and stir for 30 min until it becomes clear and transparent to obtain a gelatin solution with a solid content of 25 wt%, for later use; additionally weigh 15 g of ammonium polyphosphate, add 45 g of deionized water thereto, and then ultrasonically emulsify until it becomes clear and transparent to obtain an ammonium polyphosphate solution with a solid content of 25 wt%, for later use; mix 100 g of the gelatin solution and 60 g of the ammonium polyphosphate solution (the solid content in the mixed solution is 10%), place it in a water bath at 60 °C, heat and stir for 30 min, during which the pH change of the solution is detected. After its value stabilizes, adjust the pH of the solution to 4 - 5 with glacial acetic acid to obtain a recyclable and environmentally friendly bio-based flame retardant binder.

[0120] 2) Preparation of the transparent flame-retardant film: Pour the above solution into a non-polar polytetrafluoroethylene plate with dimensions of 200×100×2 mm 3 . After it gels, place it in air to dry at 20 °C for 24 h to obtain a water-to-bond transparent flame-retardant film.

[0121] 3) Preparation of the coated composite material: Cut the above film into the size of the surface area of the pine wood. After spraying water on one side, stick it on the surface of the pine wood, and then place it in an oven at 80 °C for curing and drying for 4 h to obtain the coated composite material.

[0122] The limiting oxygen index of the composite material is 38%, and the peak heat release is 156 kW / m 2 .

[0123] Application Example 4

[0124] Select wood chip particles as the matrix material of the particle board composite material, and the ratio of the bio-based raw material to the cross-linking agent is 5:3. The weight gain of the obtained multi-layer board composite material is 8 wt%. The specific preparation method is as follows:

[0125] 1) Preparation of the flame-retardant binder: Weigh 25 g of gelatin, add 75 g of deionized water to it, place it in a water bath at 60 °C, heat and stir for 30 min until it is clear and transparent to obtain a gelatin solution with a solid content of 25 wt%, for later use; additionally weigh 15 g of ammonium polyphosphate, add 45 g of deionized water to it, and then ultrasonically emulsify it until it is clear and transparent to obtain an ammonium polyphosphate solution with a solid content of 25 wt%, for later use; mix 100 g of the gelatin solution and 60 g of the ammonium polyphosphate solution (the solid content in the mixed solution is 10%), place it in a water bath at 60 °C, heat and stir for 30 min, during which the pH change of the solution is detected. After its value stabilizes, adjust the pH of the solution to 4 - 5 with glacial acetic acid to obtain a recyclable and environmentally friendly bio-based flame-retardant binder.

[0126] 2) Preparation of the coated composite material: Add 50 g of the solution to 60 g of dry wood chip particles, use mechanical stirring to stir them evenly, and then pour them into a mold with dimensions of 100×100×20 mm 3 . After paving and compressing, place it in an oven at 80 °C for curing and drying for 8 h to obtain a particle board composite material with a weight gain of 8 wt%.

[0127] The limiting oxygen index of the composite material is 42%, and the peak heat release is 80 kW / m 2 .

[0128] Application Example 5

[0129] The recovered experiment was carried out on the transparent flame-retardant film prepared in Application Example 3. The specific recovery method was as follows: Weigh 10 g of the crushed transparent flame-retardant film, add 50 g of deionized water thereto, and place it in a water bath at 60 °C and heat with stirring until completely dissolved. Then pour it into a non-polar polytetrafluoroethylene plate with dimensions of 200×100×2 mm 3 and let it gel and then air-dry at 20 °C for 24 h to obtain the recovered water-to-bond transparent flame-retardant film.

[0130] The limiting oxygen index of this film was 37%, and the peak heat release was 167 kW / m 2 .

[0131] Application Example 6

[0132] The recovered experiment was carried out on the flame-retardant particle board prepared in Application Example 4. The specific recovery method was as follows: Weigh 30 g of the crushed flame-retardant particle board, add 200 g of deionized water thereto, place it in a water bath at 60 °C and heat with stirring for 2 - 3 h to obtain a uniform wood particle suspension. Then immediately transfer it to a blast drying oven at 60 °C to remove the excess deionized water. Subsequently, compact the mixture in a mold, place it in a blast drying oven at 25 °C and dry for 8 h, and then raise the temperature to 80 °C and dry for another 4 h to obtain the recovered flame-retardant particle board.

[0133] The limiting oxygen index of the recovered flame-retardant particle board was 41%, and the peak heat release was 91 kW / m 2 .

[0134] The shear bond strength of the recyclable and environmentally friendly bio-based flame-retardant binder prepared in the above-mentioned examples, comparative examples and application examples was verified using a universal testing machine in accordance with GB / T 33334-2016. The limiting oxygen index test and the cone calorimeter test were carried out in accordance with GB / T 2406.3-2022 and ISO 5660-1 respectively.

[0135] Among them, Figure 1 is a schematic flow chart of the preparation method of a binder provided by the present invention, Figure 2 is a digital photo of the stratification of the mixed solution in Comparative Example 5 of the present invention; Figure 3 is a digital photo of the bonding failure in Comparative Example 7 of the present invention.

[0136] Figure 4 are the macro-morphology, micro-morphology and flame-retardant performance test result diagrams of the composite materials obtained in Application Examples 1 - 4 of the present invention; among them, Figure 4In the figure: a, a2, and a3 are respectively the macroscopic photograph, microscopic structure, and flame retardant performance of the coated foam in Application Example 1; b, b2, and b3 are respectively the macroscopic photograph, microscopic structure, and flame retardant performance of the multilayer board prepared in Application Example 2; c, c2, and c3 are respectively the macroscopic photograph, microscopic structure, and flame retardant performance of the flame retardant film prepared in Application Example 3; d, d2, and d3 are respectively the macroscopic photograph, microscopic structure, and flame retardant performance of the particle board prepared in Application Example 4. It can be seen from Figure 4 that: The recyclable and environmentally friendly bio-based flame retardant binder of the present invention has a variety of application methods and a variety of application substrates, and excellent flame retardant performance can be achieved in all cases.

[0137] Figure 5 This is the recycling process and the performance test results of the water-to-bond transparent flame retardant film and particle board composite materials obtained in Application Example 5 and Application Example 6 of the present invention; among them, Figure 5 in the figure: a and a2 are the performance test results of the materials before and after film recycling in Application Example 5; b and b2 are the performance test results of the materials before and after flame retardant particle board recycling in Application Example 6. It can be seen from Figure 5 that: The bio-based flame retardant binder and its composite materials of the present invention all have recyclable properties, and the bonding performance and flame retardancy basically remain after recycling.

[0138] The shear bonding strength test results of the recyclable and environmentally friendly bio-based flame retardant binder prepared in the above-mentioned examples, comparative examples, and application examples are summarized in Table 1 below.

[0139] Table 1

[0140]

[0141]

[0142] In summary, the present invention provides a flame retardant binder, its preparation method and application. Using biomass raw materials and cross-linking agents as raw materials, a cross-linked network is constructed driven by pH. By controlling the solid content of the binder precursor solution and the pH of the system, a bio-based binder with high bonding performance, high flame retardant performance, recyclable performance, and environmental friendliness is prepared, which can be applied to the preparation of products such as multilayer board composite materials, particle board composite materials, coating composite materials, and flame retardant films, and has wide practical uses.

[0143] The above are only specific embodiments of the present invention, enabling those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather to the broadest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for preparing a flame retardant adhesive, characterized in that: The preparation method comprises the following steps: The biomass raw material and the solvent are stirred and mixed to obtain a biomass solution; Stirring and mixing the crosslinking agent and the biomass solution to obtain a precursor solution with a solid content of 5 to 50 wt %; Adjusting the pH of the precursor solution to 3-5 to obtain the flame retardant binder; Wherein, the cross-linking agent is selected from at least one of: a silane coupling agent, a phosphoric acid compound containing an acid radical ion or a hydroxyl group, or a phosphate containing an acid radical ion or a hydroxyl group.

2. The method for preparing a flame retardant adhesive according to claim 1, characterized in that: The mass ratio of the biomass raw material to the cross-linking agent is 10:(0.5-10), preferably 10:(2-8); Furthermore, the solid content of the precursor solution is 10 to 30 wt%.

3. The method for preparing a flame retardant adhesive according to claim 1 or 2, characterized in that: The biomass raw material is selected from at least one of biomass containing hydroxyl groups and biomass containing amino groups; Further, the biomass raw material is selected from at least one of konjac gum, gelatin, gellan gum, chitosan and peach gum; Further, the phosphate compound containing acid radical ions or hydroxyl groups or the phosphate compound or the phosphate containing acid radical ions or hydroxyl groups is: ammonium polyphosphate, phosphoric acid or phytic acid dihydroxymethyl phosphine oxide; Further, the silane coupling agent is: KH550 or KH570; Furthermore, the solvent is water.

4. The method for preparing a flame retardant adhesive according to any one of claims 1 to 3, characterized in that: During the stirring and mixing process, the temperature is room temperature to 120°C, preferably 20 to 100°C.

5. A flame retardant adhesive, characterized in that: The flame retardant adhesive is prepared by the preparation method according to any one of claims 1 to 4; Furthermore, the flame retardant adhesive has a bonding strength of 5Mpa to 65Mpa, a limiting oxygen index of 23% to 40%, and a peak heat release of 50kW / m 2 ~312kW / m 2 .

6. Use of the flame retardant adhesive according to claim 5 in the preparation of a multilayer board composite material, a particle board composite material, a coating composite material or a flame retardant film.

7. A multilayer board composite material, characterized in that: The multi-layer board composite material is obtained by bonding wooden boards with the flame retardant adhesive described in claim 5 and then processing and shaping them; Furthermore, the amount of the adhesive used is 1 to 20 wt% of the weight of the wood board; Further, the wooden board includes at least one of a pine board, a fir board, a poplar board, an oak board, a teak board, an elm board, a maple board or a birch board; Furthermore, the processing and forming method includes at least one of molding, hot pressing and thermosetting.

8. A particle board composite material, characterized in that: The particle board composite material is obtained by bonding wood chip particles with the flame retardant adhesive as described in claim 5 and then processing and shaping them; Furthermore, the flame retardant binder is used in an amount of 5 to 20 wt% of the weight of the wood chip particles; Further, the wood chips include at least one of pine wood chips, fir wood chips, poplar wood chips, oak wood chips, teak wood chips, elm wood chips, maple wood chips and birch wood chips; Furthermore, the processing and forming method includes at least one of molding, hot pressing and thermosetting.

9. A composite material, characterized in that: The composite material comprises a base material and a modified layer, wherein the modified layer is a coating or film layer formed by attaching the flame retardant adhesive according to claim 5 to the surface of the base material; Wherein, the base material comprises at least one of a wood base material, a foam base material and a fabric base material; Furthermore, the wood matrix material includes at least one of pine, fir, poplar, oak, teak, elm, maple and birch, the foam matrix material includes at least one of polyurethane foam, polystyrene foam, polypropylene foam and polyimide foam, and the fabric matrix material includes at least one of cotton fabric, linen fabric, silk fabric, wool fabric, polyester fabric, acrylic fabric, spandex fabric, nylon fabric and blended fabric.

10. A flame retardant film, characterized in that: The flame retardant film is made by using the adhesive according to claim 5.

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