A low-temperature-resistant and multi-cycle-stable natural-source thermoplastic adhesive as well as a preparation method and application thereof
By combining functional components with a non-covalent interaction network formed by amino acids, hydroxy acids and sugar compounds, a naturally sourced thermoplastic adhesive with low-temperature resistance and stability after multiple cycles was constructed. This solves the problems of existing adhesives becoming brittle at low temperatures and degrading after multiple uses, and realizes a reusable and environmentally friendly adhesive system.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NANJING TECH UNIV
- Filing Date
- 2026-03-16
- Publication Date
- 2026-06-12
AI Technical Summary
Existing thermoplastic adhesives mainly rely on synthetic polymer materials, which are not environmentally friendly enough. Furthermore, adhesives from natural sources are prone to embrittlement at low temperatures and their bonding strength decreases after repeated use, making it difficult to meet the requirements of green manufacturing and sustainable development.
By forming a thermally reversible network structure with non-covalent interactions using amino acids, hydroxy acids, and sugar compounds, and combining it with functional components such as iron salts and organic acids, a naturally sourced thermoplastic adhesive with low-temperature resistance and stability over multiple cycles can be constructed.
It achieves good adhesion performance and stability under low temperature conditions and multiple cycles, avoiding the performance loss caused by traditional irreversible curing, and is reusable and environmentally friendly.
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Figure CN122188570A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of green thermoplastic materials technology, specifically relating to a low-temperature resistant and multi-cycle stable natural thermoplastic adhesive, its preparation method and application. Background Technology
[0002] Adhesives, as an important bonding material, are widely used in various fields such as wood processing, packaging, textiles, construction, and composite materials due to their ease of use and wide applicability. Traditional adhesives are mostly composed of petroleum-based polymers, typically forming a stable three-dimensional network structure through chemical cross-linking or curing reactions to achieve strong bonding between materials. However, these adhesives exhibit an irreversible structure after curing, making repeated bonding or disassembly and recycling difficult during use, limiting their applicability in sustainable applications, and also presenting certain shortcomings in terms of resource consumption and environmental impact.
[0003] To address the irreversibility issue of traditional adhesives, thermoplastic adhesives were developed. Thermoplastic adhesives soften and flow under heating conditions and return to a solid state upon cooling, offering advantages such as reusable bonding, hot-melt processing, and detachable connections. However, existing thermoplastic adhesives primarily rely on synthetic polymers such as polyethylene, polyamide, and polyester, whose raw material sources are limited and lack environmental friendliness, making it difficult to meet the requirements of green manufacturing and sustainable development. Furthermore, the synthesis systems often require high energy consumption or solvent treatment, increasing processing costs and operational complexity.
[0004] While existing natural adhesive systems are environmentally friendly, they still have several performance limitations in practical applications: at low temperatures, the colloid becomes brittle due to the restricted movement of natural component chains, leading to a significant decrease in bond strength and limiting their use in cold environments or low-temperature processing conditions; furthermore, after repeated peeling or bonding, the structure of natural adhesives tends to loosen, and the adhesive strength decays rapidly, making it difficult to achieve long-term, multiple-cycle use; at the same time, their overall bond strength and durability are still insufficient, usually requiring the introduction of chemical crosslinking agents or complex chemical modification of raw materials, which not only increases the complexity of the preparation process but may also damage the reversibility and remodelability of the material.
[0005] Therefore, how to construct a natural adhesive system that is structurally stable, simple to prepare, has excellent low-temperature resistance, is stable for recycling, and also has good adhesive properties and thermoplastic characteristics, without introducing traditional chemical crosslinking agents, by utilizing the intermolecular interactions between natural components, remains a technical problem that urgently needs to be solved in this field. Summary of the Invention
[0006] This invention addresses the aforementioned problems by providing a naturally sourced thermoplastic adhesive with low-temperature resistance and stability over multiple cycles. The thermoplastic adhesive forms a thermally reversible network structure through multi-point reversible intermolecular interactions between natural components, thereby possessing both repeatable bonding and stable bonding performance.
[0007] In the product of this invention, amino acid compounds, hydroxy acid compounds, and sugar compounds form a uniform and dense cross-linked network structure through non-covalent interactions, in which functional components are dispersed, taking into account both flexibility and rigidity, and achieving repeatable bonding and good adhesive performance.
[0008] The objective of this invention can be achieved through the following technical solutions:
[0009] A naturally sourced thermoplastic adhesive with low-temperature resistance and stability over multiple cycles, said thermoplastic adhesive comprising the following components in parts by weight:
[0010] amino acid compounds 10-60 servings Hydroxy acid compounds 30-80 servings Carbohydrates 10-50 servings Functional components 0.1 to 5 portions;
[0011] The functional components include iron salts and organic acids; wherein the iron salts are selected from one or two of anhydrous ferric chloride and ferrous chloride, and the organic acids are one or more of phytic acid or its low-phosphorylated derivatives; the low-phosphorylated derivatives are inositol 1,3,4,5-tetraphosphate (CAS: 210488-61-2), inositol (1,4,5) triphosphate (CAS: 85166-31-0), or inositol 1,4-diphosphate (CAS: 74465-19-3); the mass ratio of organic acid to iron salt is 1:0.5~2.
[0012] In some preferred embodiments, the thermoplastic adhesive comprises the following components in parts by weight:
[0013] amino acid compounds 30-40 servings Hydroxy acid compounds 40-50 servings Carbohydrates 20-35 servings Functional components 0.5 to 2 portions.
[0014] In the technical solution of this invention, the amino acid compound is one or more of glycine, alanine, leucine, proline, serine, lysine and their derivatives.
[0015] In the technical solution of this invention, the hydroxy acid compound is one or more of lactic acid, tartaric acid, glycolic acid, malic acid, citric acid, mandelic acid, and gluconic acid.
[0016] In the technical solution of this invention, the carbohydrate compound is one or more of chitosan, cellulose, xanthan gum, arabinose, xylose, glucose, fructose, mannose, sorbitol, xylitol, and erythritol.
[0017] A method for preparing the above-mentioned low-temperature resistant and cycle-stable thermoplastic adhesive from a natural source, the method comprising the following steps:
[0018] 1) Mix amino acid compounds and hydroxy acid compounds in water and heat at 60~120 ℃ for 4~8 h to obtain an amino acid-hydroxy acid mixed solution;
[0019] 2) Add carbohydrate compounds and functional components to the mixed solution obtained in step 1), and then heat at 60~120 °C for 24~48 h to obtain an amber mixed solution;
[0020] 3) The mixed solution obtained in step 2) is subjected to vacuum distillation at 100~120 °C to obtain a viscous thermoplastic adhesive from a natural source that is resistant to low temperatures and stable in multiple cycles.
[0021] In the above method, the vacuum distillation in step 3) is carried out under vacuum distillation at a pressure of 0.01~0.08 MPa.
[0022] The application of the low-temperature resistant and cycle-stable natural thermoplastic adhesive described in this invention in bonding steel, wood, paper, fiber materials, leather, plastics, rubber, or their composite materials.
[0023] The low-temperature resistant and cycle-stable thermoplastic adhesive from natural sources described in this invention can form a homogeneous melt system under heating conditions. Amino acid compounds, containing both amino and carboxyl groups, form an internal salt structure within the system and act as the main functional unit, constructing the continuous phase framework of the adhesive through multi-point hydrogen bonding and ionic interactions. Hydroxy acid compounds, through synergistic interactions with amino acids via hydroxyl and carboxyl groups, act as flexible linking units to regulate the system's fluidity, enabling the adhesive to exhibit good melting properties under heating conditions and maintain a stable viscoelastic state after cooling. Sugar compounds, relying on their polyhydroxy structure, form a high-density hydrogen bond network within the system, not only increasing the spatial density of interaction points and the interfacial wetting ability of the substrate surface, but also synergistically interacting with functional components to induce the formation of polynuclear metal coordination aggregates or locally enriched coordination crosslinking domains. These coordination aggregates exhibit uniformly dispersed spherical or near-spherical crosslinking nodes, significantly improving the stability and crosslinking density of the adhesive network without compromising the thermoplastic processability of the continuous phase, thereby enhancing the uniformity, durability, and cycle-stable performance of the adhesive layer. The adhesive can be used for bonding wood, paper, fiber materials, leather, plastics and their composites.
[0024] In this invention, the functional components include a polyvalent metal salt and an organic polydentate coordination compound. The polyvalent metal salt is preferably anhydrous ferric chloride, ferrous chloride, or a derivative thereof, and the organic polydentate coordination compound is preferably phytic acid or a derivative thereof. These functional components work synergistically to enhance the interaction between the adhesive and the adherend interface and to improve the cohesive strength of the adhesive.
[0025] In the technical solution of this invention, the low-temperature resistant and multi-cycle stable natural thermoplastic adhesive has components that interact through hydrogen bonding, ionic interaction, coordination, and some reversible coordination bonds or dynamic interactions, enabling the adhesive to exhibit thermoplastic flow characteristics under heating conditions and form a stable adhesive structure after cooling.
[0026] In the low-temperature resistant and multi-cycle stable thermoplastic adhesive system from natural sources, amino acids, hydroxy acids and sugar compounds all contain abundant polar functional groups, including amino, carboxyl, hydroxyl and their derivative structures. These functional groups work synergistically during heating to construct a multi-functional system mainly based on hydrogen bond networks, ion interactions and coordination.
[0027] The amino and carboxyl groups in amino acid molecules attract each other with positive and negative charges, forming a self-locking network structure within the molecule. They also form a stable hydrogen bond network with hydroxy acids and sugar compounds, enhancing the cohesive force of the system. Hydroxy acid molecules not only act as reaction media and structure regulating components, but can also form coordination structures with metal ions or polyphenolic functional components through carboxyl groups, thereby enhancing the overall stability of the adhesive system.
[0028] The abundant hydroxyl groups in carbohydrate molecules provide a high density of hydrogen bond donor and acceptor sites for the adhesive system. This enhances the cohesive strength of the system while significantly improving the wettability and interfacial interaction of the adhesive on substrates such as steel, wood, and paper, facilitating the formation of a continuous, dense, and uniform adhesive layer at the interface. The polyvalent metal ions in the functional components further coordinate or complex with the hydroxyl groups and related functional groups in the carbohydrate compounds, forming uniformly dispersed multi-point coordination aggregates or locally enriched cross-linking nodes in the system, thereby introducing reversible "physical cross-linking points." Within the specified mass ratio range, the polyvalent metal ions are embedded in the hydrogen bond network constructed by the carbohydrate compounds in an unsaturated coordination state, and their cross-linking density is effectively controlled. This prevents the system from becoming excessively soft due to insufficient cross-linking, or from becoming overly brittle at low temperatures or experiencing a decrease in thermoplastic reversibility due to excessive cross-linking. The aforementioned sparse and stable physical cross-linking structure can maintain sufficient segment mobility under low temperature conditions and achieve reversible reconstruction of interactions during multiple heating-cooling cycles, thereby enabling the adhesive to exhibit stable bonding performance and good structural integrity under low temperature environment and repeated use conditions.
[0029] This invention solves the problems of existing natural adhesive systems that rely on chemical crosslinking or irreversible curing, are difficult to reuse, and are prone to embrittlement and significant degradation of adhesive performance at low temperatures. Through a multi-point, reversible intermolecular interaction network constructed between natural components, under heating conditions, this interaction can partially dissociate or rearrange, causing the adhesive system to exhibit a molten or highly fluid dynamic state. During cooling, intermolecular hydrogen bonds, ionic interactions, and coordination interactions reform and synergistically fix the structure, thereby achieving a reversible transition of the adhesive from a fluid dynamic state to a solid or highly viscoelastic state. Unlike traditional natural adhesives that rely on rigid crosslinking structures, the molecular interaction network constructed in this invention retains a certain degree of structural tunability and chain segment mobility at low temperatures, effectively alleviating chain segment freezing and stress concentration caused by temperature reduction, thus avoiding colloid embrittlement and a sharp decline in adhesive strength. This characteristic gives the adhesive the advantages of being heat-melt processable, reusable, and remodelable, effectively overcoming the problems of traditional natural adhesives relying on irreversible chemical crosslinking, performance degradation at low temperatures, and difficulty in reuse.
[0030] The low-temperature resistant and multi-cycle stable natural thermoplastic adhesive of the present invention has a simple and controllable preparation process. The preparation process does not require the introduction of traditional chemical crosslinking agents or organic solvents. The conditions are mild, safe and stable, and it has good environmental friendliness and application promotion value.
[0031] Technical effects:
[0032] 1. The low-temperature resistant and cycle-stable thermoplastic adhesive from natural sources described in this invention contains abundant polar functional groups, which can form a stable cohesive network structure through hydrogen bonding, ionic interactions and coordination, significantly improving the adhesive strength and interfacial adaptability of the adhesive.
[0033] 2. Through composite synergistic effect, the high cohesive strength and good interfacial adhesion performance of adhesives are achieved without the introduction of traditional petrochemical-based crosslinking agents.
[0034] 3. The adhesive exhibits good thermoplastic flow behavior under heating conditions and rapidly recovers its bonding strength after cooling, possessing the advantages of reversible bonding, excellent low-temperature resistance, and reusability.
[0035] 4. Since the system mainly relies on non-covalent interactions to build the structural network, it avoids the performance loss problem of traditional irreversible curing adhesives during recycling and reprocessing.
[0036] 5. All components of the adhesive are derived from natural or renewable resources, reducing dependence on petrochemical resources and exhibiting good environmental friendliness and sustainability. Attached Figure Description
[0037] Figure 1This is an SEM image of the adhesive used to bond glass in Example 4.
[0038] Figure 2 This is an EDX image of the adhesive bonding glass in Example 4. Detailed Implementation
[0039] The present invention will be further described below with reference to specific embodiments. The following examples are for illustrative purposes only and do not limit the present invention. Unless otherwise specified, the reagents used in the following examples are conventional reagents available in the art; the methods used, unless otherwise specified, are conventional methods in the art.
[0040] Example 1.1:
[0041] First, weigh 32 parts by mass of glycine, 44 parts by mass of lactic acid, 22.5 parts by mass of sorbitol, 1 part by mass of phytic acid, and 0.5 parts by mass of ferrous chloride, and place them separately in a drying oven and dry at 100 °C for 2 h. Dissolve the dried glycine and lactic acid in neutral deionized water and heat to 90 °C for 6 h under magnetic stirring to obtain a homogeneous and transparent amino acid-hydroxy acid mixed solution. Add sorbitol, phytic acid, and ferrous chloride to the above mixed solution, and continue stirring and heating at 90 °C for 24 h to allow the functional components to be fully dispersed in the system and form stable multi-point coordination, resulting in a homogeneous light brown viscous system. Place the system at 110 °C (0.01~0.08 MPa) for 18 h to obtain a natural thermoplastic adhesive with low-temperature resistance and stability after multiple cycles. The obtained adhesive was heated to 90 °C to soften it and then applied to the surface of a steel substrate. It was bonded under a pressure of 0.5 MPa for 5 min and cooled to room temperature to form a stable bond structure. The shear strength of the adhesive was tested using a New Sansi C42.104 universal testing machine.
[0042] Comparative Example 1.2:
[0043] The functional component in Example 1 was replaced with 1 part by mass of phytic acid, and the rest was the same as in Example 1.
[0044] Comparative Example 1.3:
[0045] The functional component in Example 1 was replaced with 0.5 parts by mass of ferrous chloride, and the rest was the same as in Example 1.
[0046] Comparative Example 1.4:
[0047] The mass ratio of phytic acid and ferrous chloride in Example 1 was changed to 3:1, and the rest was the same as in Example 1.
[0048] Comparative Example 1.5:
[0049] Except for the absence of 1 part by weight of phytic acid and 0.5 parts by weight of ferrous chloride, the rest is the same as in Example 1.
[0050] Example 2.1:
[0051] First, weigh 30 parts by weight of alanine, 46 parts by weight of malic acid, 22.5 parts by weight of xylitol, 1 part by weight of phytic acid, and 0.5 parts by weight of anhydrous ferric chloride, and dry them at 95 °C for 2 h. Dissolve alanine and malic acid in neutral deionized water and heat at 85 °C for 8 h with stirring to form a homogeneous and transparent solution. Add xylitol, phytic acid, and anhydrous ferric chloride sequentially, and continue heating at 90 °C for 24 h to allow the functional components to be fully dispersed in the system and form stable multi-point coordination, resulting in a homogeneous, deep yellow, viscous system. Place the system under reduced pressure (0.01~0.08 MPa) at 115 °C for 20 h to obtain a naturally derived thermoplastic adhesive with low-temperature resistance and stability after multiple cycles. The obtained adhesive was heated to 90 °C to soften it and then applied to the surface of a steel substrate. It was bonded under a pressure of 0.5 MPa for 5 min and cooled to room temperature to form a stable bond structure. The shear strength of the adhesive was tested using a New Sansi C42.104 universal testing machine.
[0052] Comparative Example 2.2:
[0053] The functional component in Example 2 was changed to 1 part by mass of phytic acid, and the rest was the same as in Example 2.
[0054] Comparative Example 2.3:
[0055] The functional component in Example 2 was changed to 0.5 parts by mass of anhydrous ferric chloride, and the rest was the same as in Example 2.
[0056] Comparative Example 2.4:
[0057] The mass ratio of phytic acid and anhydrous ferric chloride in Example 2 was changed to 3:1, and the rest was the same as in Example 2.
[0058] Comparative Example 2.5:
[0059] Except for the omission of 1 part by weight of phytic acid and 0.5 parts by weight of anhydrous ferric chloride, the rest is the same as in Example 2.
[0060] Example 3.1:
[0061] First, weigh 28 parts by mass of serine, 48 parts by mass of citric acid, 22.5 parts by mass of glucose, 1 part by mass of phytic acid, and 0.5 parts by mass of ferrous chloride, and dry them at 95 °C for 2 h. Dissolve serine and citric acid in neutral deionized water and heat at 90 °C for 6 h with stirring to form a homogeneous and transparent solution. Add glucose, phytic acid, and ferrous chloride sequentially, and continue heating for 24 h to allow the functional components to be fully dispersed in the system and form stable multi-point coordination, resulting in a deep amber homogeneous system. Place the system under reduced pressure (0.01~0.08 MPa) at 110 °C for 18 h to obtain a natural thermoplastic adhesive with low-temperature resistance and stability after multiple cycles. Soften the obtained adhesive by heating it to 90 °C and then coat it onto the surface of a steel substrate. Bond it under 0.5 MPa pressure for 5 min, and after cooling to room temperature, a stable bond structure is formed. The shear strength of the adhesive is tested using a New Sansi C42.104 universal testing machine.
[0062] Comparative Example 3.2:
[0063] The functional component in Example 3 was changed to 1 part by mass of phytic acid, and the rest was the same as in Example 3.
[0064] Comparative Example 3.3:
[0065] The functional component in Example 3 was replaced with 0.5 parts by mass of ferrous chloride, and the rest was the same as in Example 3.
[0066] Comparative Example 3.4:
[0067] The mass ratio of phytic acid and ferrous chloride in Example 3 was changed to 3:1, and the rest was the same as in Example 3.
[0068] Comparative Example 3.5:
[0069] Except for the omission of 1 part by weight of phytic acid and 0.5 parts by weight of ferrous chloride, the rest is the same as in Example 3.
[0070] Example 4.1:
[0071] First, weigh 34 parts by mass of proline, 42 parts by mass of glycolic acid, 22.5 parts by mass of arabinose, 1 part by mass of phytic acid, and 0.5 parts by mass of anhydrous ferric chloride, and dry them at 100 °C for 2 h. Dissolve proline and glycolic acid in neutral deionized water and heat at 90 °C for 6 h with stirring to form a homogeneous and transparent solution. Add arabinose, phytic acid, and anhydrous ferric chloride sequentially, and continue heating for 24 h to allow the functional components to be fully dispersed in the system and form stable multi-point coordination, resulting in a deep amber homogeneous system. Place the system at 100 °C (0.01~0.08 MPa) for 20 h to obtain a naturally derived thermoplastic adhesive with low-temperature resistance and stability after multiple cycles. The obtained adhesive was heated to 90 °C to soften it and then applied to the surface of a steel substrate. It was bonded under a pressure of 0.5 MPa for 5 min and cooled to room temperature to form a stable bond structure. The shear strength of the adhesive was tested using a New Sansi C42.104 universal testing machine.
[0072] Comparative Example 4.2:
[0073] The functional component in Example 4 was changed to 1 part by mass of phytic acid, and the rest was the same as in Example 4.
[0074] Comparative Example 4.3:
[0075] The functional component in Example 4 was replaced with 0.5 parts by mass of anhydrous ferric chloride, and the rest was the same as in Example 4.
[0076] Comparative Example 4.4:
[0077] The mass ratio of phytic acid and anhydrous ferric chloride in Example 4 was changed to 3:1, and the rest was the same as in Example 4.
[0078] Comparative Example 4.5:
[0079] Except for the omission of 1 part by weight of phytic acid and 0.5 parts by weight of anhydrous ferric chloride, the rest is the same as in Example 4.
[0080] Experimental Example
[0081] The thermoplastic adhesive obtained in the embodiments of the present invention needs to be heated (80~100 ℃, 0.5MPa, 5 min) for thermocuring after application.
[0082] The testing adopts the following national standards:
[0083] Test GB / T 7124-2008: Determination of tensile shear strength of adhesives.
[0084] The test results are shown in Tables 1 and 2.
[0085] Table 1 Comparison of shear strength and shear strength after at least 30 repeated bonding cycles of adhesives
[0086] adhesive Shear strength / MPa Shear strength (30 cycles) / MPa adhesive Shear strength / MPa Shear strength (30 cycles) / MPa Example 1.1 13.12 9.86 Example 3.1 17.28 14.77 Comparative Example 1.2 9.95 7.54 Comparative Example 3.2 14.43 12.32 Comparative Example 1.3 8.58 6.23 Comparative Example 3.3 12.15 10.47 Comparative Example 1.4 7.14 5.32 Comparative Example 3.4 11.18 9.25 Comparative Example 1.5 5.64 4.26 Comparative Example 3.5 9.54 8.48 Example 2.1 15.84 13.58 Example 4.1 17.47 15.89 Comparative Example 2.2 8.31 6.21 Comparative Example 4.2 12.51 10.11 Comparative Example 2.3 7.54 5.89 Comparative Example 4.3 11.98 9.87 Comparative Example 2.4 4.92 3.67 Comparative Example 4.4 9.32 7.58 Comparative Example 2.5 2.94 1.99 Comparative Example 4.5 7.54 5.48
[0087] Table 2 Comparison of Low Temperature Resistance and Water Repellency of Adhesives
[0088] adhesive Shear strength at low temperature (-80°C) / MPa Hydrophobicity adhesive Shear strength at low temperature (-80°C) / MPa Hydrophobicity Example 1.1 12.55 78.4% Example 3.1 16.45 67.5% Comparative Example 1.2 8.86 53.2% Comparative Example 3.2 13.57 47.8% Comparative Example 1.3 7.73 51.4% Comparative Example 3.3 11.26 45.6% Comparative Example 1.4 6.88 44.3% Comparative Example 3.4 10.45 41.8% Comparative Example 1.5 4.74 29.3% Comparative Example 3.5 8.78 27.6% Example 2.1 14.62 69.8% Example 4.1 16.82 78.6% Comparative Example 2.2 7.94 50.6% Comparative Example 4.2 11.93 55.1% Comparative Example 2.3 6.81 48.9% Comparative Example 4.3 9.66 52.7% Comparative Example 2.4 4.57 46.1% Comparative Example 4.4 7.99 47.2% Comparative Example 2.5 2.47 30.3% Comparative Example 4.5 6.28 31.8%
[0089] Through analysis Figure 1 and Figure 2 It can be seen that the thermoplastic adhesive has a good bonding effect on the steel substrate, and the integrity of the adhesive layer is well maintained during the bonding process, showing strong cohesive ability.
[0090] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.
Claims
1. A naturally derived thermoplastic adhesive with low-temperature resistance and stability over multiple cycles, characterized in that, The thermoplastic adhesive comprises the following components in parts by weight. composition: The functional components include iron salts and organic acids; wherein the iron salts are selected from one or two of anhydrous ferric chloride and ferrous chloride, and the organic acids are one or more of phytic acid or its low phosphorylation derivatives; the low phosphorylation derivatives are inositol 1,3,4,5-tetraphosphate, inositol (1,4,5) triphosphate, or inositol 1,4-diphosphate; the mass ratio of organic acid to iron salt is 1:0.5~2.
2. The low-temperature resistant and cycle-stable natural-source thermoplastic adhesive according to claim 1, characterized in that, The thermoplastic adhesive comprises the following components in parts by weight. composition:
3. The low-temperature resistant and cycle-stable natural-source thermoplastic adhesive according to claim 1, characterized in that, The amino acid compound is one or more of glycine, alanine, leucine, proline, serine, lysine, and their derivatives.
4. The low-temperature resistant and cycle-stable natural-source thermoplastic adhesive according to claim 1, characterized in that, The hydroxy acid compound is one or more of lactic acid, tartaric acid, glycolic acid, malic acid, citric acid, mandelic acid, and gluconic acid.
5. The low-temperature resistant and multi-cycle stable thermoplastic adhesive from a natural source according to claim 1, characterized in that, The carbohydrate compound is one or more of chitosan, cellulose, xanthan gum, arabinose, xylose, glucose, fructose, mannose, sorbitol, xylitol, and erythritol.
6. A method for preparing the low-temperature resistant and multi-cycle stable thermoplastic adhesive of any one of claims 1-5, characterized in that, Includes the following steps: 1) Mix amino acid compounds and hydroxy acid compounds in water and heat at 60~120 ℃ for 4~8 h to obtain an amino acid-hydroxy acid mixed solution; 2) Add carbohydrate compounds and functional components to the mixed solution obtained in step 1), and then heat at 60~120 °C for 24~48 h to obtain an amber mixed solution; 3) The mixed solution obtained in step 2) is subjected to vacuum distillation at 100~120 °C to obtain a viscous thermoplastic adhesive from a natural source that is resistant to low temperatures and stable in multiple cycles.
7. The method according to claim 6, characterized in that, The conditions for vacuum distillation in step 3) are vacuum distillation at a pressure of 0.01~0.08 MPa.
8. The use of the low-temperature resistant and cycle-stable natural-source thermoplastic adhesive of claim 1 in bonding steel, wood, paper, fiber materials, leather, plastics, rubber or composite materials thereof.