Starch adhesive for artificial board and preparation method of starch adhesive

Abstract

The invention relates to the technical field of adhesives, in particular to a starch adhesive for artificial boards and a preparation method of the starch adhesive, and the starch adhesive comprises the following components in parts by weight: 100 parts of modified konjac starch, 15-25 parts of polyvinyl alcohol, 8-12 parts of polyacrylate, 0.1-0.3 part of a preservative, 3-6 parts of epoxy chloropropane, 0.5-1.0 part of a viscosity stabilizer, 2-4 parts of a modified rare earth compound and 180-220 parts of water. According to the invention, a composite adhesive system of'modified starch matrix + chemical cross-linked network + rare earth coordination interface 'is constructed, so that the water resistance and the bonding strength can be obviously improved; meanwhile, the formaldehyde emission is zero, the problem of formaldehyde pollution of urea-formaldehyde resin, phenolic resin and other traditional adhesives is avoided, and an adhesive solution with high performance and environment-friendly characteristics is provided for the artificial board industry.

Description

Technical Field

[0001] The present invention relates to the technical field of adhesives, in particular to a starch adhesive for artificial boards and a preparation method thereof. Background Art

[0002] Traditional adhesives such as urea-formaldehyde resins and phenol-formaldehyde resins, which are currently widely used in the wood-based panel industry, have serious formaldehyde emission problems, which have adverse effects on human health and the environment. With the increasingly stringent national environmental protection standards and the continuous improvement of consumers' environmental awareness, the development of environmentally friendly adhesives with no formaldehyde or low formaldehyde emission has become an urgent need for the development of the industry. Natural starch-based adhesives, as renewable and biodegradable green adhesives, have significant advantages such as a wide range of raw material sources, low cost, and no formaldehyde emission. They are considered to be an ideal choice to replace traditional formaldehyde-containing adhesives. However, insufficient water resistance is the core technical bottleneck that restricts natural starch-based adhesives from replacing traditional adhesives. Traditional starch-based adhesives form a physical network only through hydrogen bonding between molecules, and are prone to swelling and dissociation in aqueous media, resulting in a sudden drop in bonding strength.

[0003] In the prior art, CN201810307519.2 discloses a starch adhesive and its preparation process. The technical solution includes 100 parts of corn starch, 300-340 parts of water, 4-6 parts of pregelatinizer, 80-90 parts of gelatinizer, 3-5 parts of oxidant, 10-14 parts of cross-linker, 50-60 parts of thickener, 1-2 parts of catalyst, and 4-6 parts of drying agent. The starch adhesive is prepared through premixing, pregelatinization, oxidation and cross-linking processes, which mainly solves the technical problem of long curing time of starch adhesive. However, this existing technology still has obvious technical defects: first, this technical solution is mainly aimed at paper adhesive applications, and its water resistance and mechanical strength are difficult to meet the strict requirements of the wood-based panel industry; second, the cross-linking system used in the existing technology mainly relies on a single chemical cross-linking agent, and the cross-linking density and cross-linking efficiency are limited, making it difficult to construct a high-strength, long-lasting and stable three-dimensional network structure; third, there is a lack of an effective interface enhancement mechanism, and the interface bonding between the adhesive and the wood substrate mainly relies on physical adsorption and hydrogen bonding, with low bonding strength, and interfacial failure is prone to occur in a humid and hot environment. Summary of the Invention

[0004] In view of this, the present invention proposes a starch-based adhesive for artificial boards and a preparation method thereof to solve the technical problems in the prior art that starch-based adhesives have poor water resistance and low bonding strength and cannot meet the requirements of industrial production of artificial boards.

[0005] The technical solution of the present invention is achieved as follows: The present invention provides a starch adhesive for artificial boards, which comprises, by weight, 100 parts of modified konjac starch, 15-25 parts of polyvinyl alcohol, 8-12 parts of polyacrylate, 0.1-0.3 parts of preservative, 3-6 parts of epichlorohydrin, 0.5-1.0 parts of viscosity stabilizer, 2-4 parts of modified rare earth compound and 180-220 parts of water.

[0006] In the present invention, modified konjac starch is used as the main adhesive to provide basic bonding performance and film-forming properties, and its high molecular weight and good rheological properties lay a solid foundation for the adhesive; polyvinyl alcohol significantly improves the cohesive strength and toughness of the adhesive layer through molecular chain entanglement and hydrogen bonding, and at the same time improves the processing performance of the adhesive; polyacrylate is used as a flexibility improver to effectively improve the impact resistance and low-temperature flexibility of the adhesive layer and prevent brittle fracture; epichlorohydrin is used as a key cross-linking agent to undergo a chemical cross-linking reaction with hydroxyl groups on the starch and polyvinyl alcohol molecular chains to construct a stable three-dimensional network structure, fundamentally solving the technical defects of traditional starch adhesives that rely solely on physical effects; the modified rare earth complex plays a dual function. On the one hand, its rare earth ions form coordination bonds with the hydroxyl groups on the wood surface, significantly enhancing the interface bonding, which is beneficial to improving the bonding effect between the adhesive and the artificial board, and at the same time, the introduced hydrophobic groups effectively prevent moisture penetration; the preservative and viscosity stabilizer respectively ensure the storage stability and construction applicability of the adhesive. Through the synergistic effect of various components, a multiple water-resistant system of "chemical cross-linking network + coordination bonding interface + hydrophobic protective layer" is formed, so that the adhesive has good water resistance and bonding strength while maintaining the environmentally friendly characteristics of completely formaldehyde-free.

[0007] Based on the above technical solution, preferably, the preparation method of the modified konjac starch comprises: mixing konjac starch and water, adding 10% sodium hydroxide solution under continuous stirring, heating to 40-45° C., adding 30% sodium hypochlorite solution, and reacting for 30-50 minutes to obtain the modified konjac starch.

[0008] Compared to traditional corn starch and wheat starch, konjac starch has a higher molecular weight and better film-forming properties. Furthermore, the gels formed from konjac starch possess high strength, high elasticity, and excellent thermal stability, with gel strengths up to 2-3 times that of ordinary starch. This invention, through oxidative modification of konjac starch and the introduction of carboxyl or hydroxyl groups, enhances the cohesive strength and bonding properties of the adhesive. It also improves the starch's compatibility with components such as polyvinyl alcohol and polyacrylates, ensuring the uniformity and stability of the adhesive system.

[0009] On the basis of the above technical solution, preferably, the mass ratio of the konjac starch, sodium hydroxide solution and sodium hypochlorite solution added is 100:15-20:8-12.

[0010] On the basis of the above technical solution, preferably, the preparation method of the modified rare earth composite comprises:

[0011] Disperse 1,3-bis(2',4'-bis(glycidyl ether)phenyl)adamantane in anhydrous toluene, add γ-aminopropyltriethoxysilane and triethylamine under nitrogen protection, raise the temperature to 80-85°C, and react for 3-5 hours to obtain a modified silane coupling agent;

[0012] The rare earth oxide is dispersed in anhydrous toluene, and a modified silane coupling agent is added under nitrogen protection. The temperature is raised to 100-120° C., and the mixture is condensed and refluxed for 3-4 hours to obtain a modified rare earth composite.

[0013] Based on the above technical solution, preferably, the mass ratio of the 1,3-bis(2',4'-bis(glycidyl ether)phenyl)adamantane, γ-aminopropyltriethoxysilane and triethylamine is 100:45-50:0.5-1.0.

[0014] On the basis of the above technical solution, preferably, the rare earth oxide is cerium oxide and / or lanthanum oxide.

[0015] Specifically, under the action of the alkaline catalyst triethylamine, the amino groups in the γ-aminopropyltriethoxysilane molecule and the epoxy groups in the 1,3-bis(2',4'-bis(glycidylether)phenyl)adamantane undergo an epoxy ring-opening reaction to produce a modified silane coupling agent. This then undergoes a condensation reaction with the hydroxyl groups on the surface of the rare earth oxide, loading the modified silane coupling agent onto the surface of the rare earth oxide. The rare earth ions form stable coordination complexes with the newly introduced carboxyl groups on the starch molecular chains, while simultaneously catalyzing the crosslinking reaction between epichlorohydrin and the starch hydroxyl groups, creating a dual network structure of "coordinate bonds + covalent bonds." Furthermore, the adamantane introduced on the surface of the rare earth oxide acts as a hydrophobic group, forming hydrophobic microdomains within the adhesive layer, effectively blocking the permeation pathways of water molecules and significantly improving the adhesive's water resistance.

[0016] On the basis of the above technical solution, preferably, the mass ratio of the rare earth oxide to the modified silane coupling agent is 10:2-4.

[0017] On the basis of the above technical solution, preferably, the preservative is one or more of sodium benzoate, potassium sorbate or calcium propionate.

[0018] On the basis of the above technical solution, preferably, the viscosity stabilizer is one or more of sodium carboxymethyl cellulose, xanthan gum or guar gum.

[0019] The present invention provides a method for preparing a starch adhesive for artificial boards, comprising the following steps:

[0020] (1) Add modified konjac starch to deionized water, stir evenly, and gelatinize at 60°C for 30-40 min to obtain modified konjac starch paste;

[0021] (2) adding polyvinyl alcohol to deionized water to prepare a polyvinyl alcohol solution with a concentration of 15-20%, cooling to room temperature, then adding polyacrylate, preservative, viscosity stabilizer and modified rare earth oxide, stirring evenly to obtain a mixed solution;

[0022] (3) Slowly add the mixed solution into the modified konjac starch paste, stir and mix at 35-45°C for 15-25 minutes, then add epichlorohydrin and continue stirring for 2-3 hours to obtain a starch adhesive.

[0023] The starch adhesive for artificial panels and its preparation method of the present invention have the following beneficial effects compared with the prior art:

[0024] (1) The present invention successfully solves the core technical problem of poor water resistance of traditional starch-based adhesives by constructing a composite adhesive system of "modified starch matrix + chemical cross-linking network + rare earth coordination interface". Compared with existing technologies, the adhesive of the present invention can significantly improve water resistance and bonding strength. At the same time, the formaldehyde emission is zero, avoiding the formaldehyde pollution problem of traditional adhesives such as urea-formaldehyde resin and phenolic resin, providing an adhesive solution with both high performance and environmental protection for the wood-based panel industry.

[0025] (2) A composite reinforcing agent with both hydrophobic protection and coordination enhancement was obtained by step-by-step modification and synthesis of 1,3-bis(2',4'-bis(glycidyl ether)phenyl)adamantane, γ-aminopropyltriethoxysilane and rare earth oxides. The adamantane group formed a hydrophobic micro-region in the adhesive layer, effectively blocking water penetration. The coordination bond strength formed by the rare earth ions and the hydroxyl groups on the wood surface was much higher than the hydrogen bond force, achieving enhanced anchoring of the adhesive-substrate interface. At the same time, the rare earth ions can significantly reduce the activation energy of the epoxy ring-opening reaction, greatly increase the crosslinking density, and significantly shorten the curing time.

[0026] (3) Konjac starch was oxidatively modified using an alkaline oxidation system of sodium hydroxide and sodium hypochlorite, effectively introducing active functional groups, significantly improving its reactivity compared to native starch. The modified konjac starch not only maintained its original high molecular weight and excellent film-forming properties, but also acquired chemical reactivity with cross-linking components such as epichlorohydrin and rare earth ions, providing sufficient reaction sites for constructing a stable three-dimensional cross-linked network. DETAILED DESCRIPTION

[0027] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0028] It should be noted that, in the examples of the present invention, konjac starch was purchased from Henan Jinyi Biotechnology Co., Ltd.; polyacrylate is specifically polyacrylate emulsion, purchased from Beijing Planaxin Co., Ltd.; polyvinyl alcohol was purchased from Shanghai Yuanye Biotechnology Co., Ltd., with item number S30196.

[0029] Example 1

[0030] This embodiment provides a starch adhesive for artificial panels. The adhesive comprises, by weight, 100 parts of modified konjac starch, 20 parts of polyvinyl alcohol, 10 parts of polyacrylate, 0.2 parts of potassium sorbate, 4.5 parts of epichlorohydrin, 0.8 parts of xanthan gum, 3 parts of modified rare earth compound, and 200 parts of water. The preparation method is as follows:

[0031] (1) Add modified konjac starch to deionized water, stir evenly, and gelatinize at 60°C for 35 minutes to obtain modified konjac starch paste;

[0032] (2) adding polyvinyl alcohol to deionized water to prepare a polyvinyl alcohol solution with a concentration of 18%, cooling to room temperature, then adding polyacrylate, xanthan gum, potassium sorbate and modified rare earth oxide, stirring evenly to obtain a mixed solution;

[0033] (3) The mixed solution was slowly added to the modified konjac starch paste, stirred at 30 °C for 20 min, and then epichlorohydrin was added and stirred for 2.5 h. The solid content of the adhesive was adjusted to 48% to obtain a starch adhesive.

[0034] The preparation method of the modified konjac starch comprises: mixing 100g of konjac starch and 500ml of water, stirring at room temperature for 30 minutes to fully disperse the mixture, adding 18g of a 10% sodium hydroxide solution while continuously stirring, adjusting the pH of the solution to alkaline, heating the mixture to 43°C, adding 10g of a 30% sodium hypochlorite solution, reacting the mixture for 40 minutes, and after the reaction is completed, adjusting the pH to 7.0-7.5 with a 10% dilute hydrochloric acid solution to terminate the oxidation reaction, dialyzing the mixture, concentrating under reduced pressure, drying, and sieving to obtain the modified konjac starch.

[0035] The preparation method of the modified rare earth composite comprises:

[0036] Disperse 100 g of 1,3-bis(2',4'-bis(glycidyl ether)phenyl)adamantane in 1000 ml of anhydrous toluene. Add 48 g of γ-aminopropyltriethoxysilane and 0.8 g of triethylamine under nitrogen protection. Heat to 83°C and reflux for 4 h. After the reaction is complete, cool to room temperature, evaporate to remove the toluene solvent under reduced pressure, and wash with anhydrous ethanol and dry to obtain a modified silane coupling agent.

[0037] 100 g of cerium oxide was dried and dehydrated, then dispersed in 1000 ml of anhydrous toluene and ultrasonically dispersed for 20 minutes. Under nitrogen protection, 30 g of modified silane coupling agent was added, and the temperature was raised to 100° C. and condensed and refluxed for 3.5 hours. After the reaction was completed, it was filtered, washed, and dried to obtain a modified rare earth composite.

[0038] Example 2

[0039] This embodiment provides a starch adhesive for artificial panels. The adhesive comprises, by weight, 100 parts of modified konjac starch, 15 parts of polyvinyl alcohol, 8 parts of polyacrylate, 0.1 parts of potassium sorbate, 3 parts of epichlorohydrin, 0.5 parts of xanthan gum, 2 parts of modified rare earth compound, and 180 parts of water. The preparation method is as follows:

[0040] (1) Add modified konjac starch to deionized water, stir evenly, and gelatinize at 60°C for 30 min to obtain modified konjac starch paste;

[0041] (2) adding polyvinyl alcohol to deionized water to prepare a polyvinyl alcohol solution with a concentration of 15%, cooling to room temperature, then adding polyacrylate, xanthan gum, potassium sorbate and modified rare earth oxide, stirring evenly to obtain a mixed solution;

[0042] (3) The mixed solution was slowly added to the modified konjac starch paste, stirred at 35 °C for 25 min, and then epichlorohydrin was added and stirred for 3 h. The solid content of the adhesive was adjusted to 45% to obtain a starch adhesive.

[0043] The preparation method of the modified konjac starch comprises the following steps: mixing 100 g of konjac starch and 500 ml of water, stirring at room temperature for 30 minutes to fully disperse the mixture, adding 15 g of a 10% sodium hydroxide solution while continuously stirring, adjusting the pH of the solution to alkaline, heating the mixture to 40° C., adding 8 g of a 30% sodium hypochlorite solution, reacting the mixture for 50 minutes, and after the reaction is completed, adjusting the pH to 7.0-7.5 with a 10% dilute hydrochloric acid solution to terminate the oxidation reaction, dialyzing the mixture, concentrating the mixture under reduced pressure, drying, and sieving the mixture to obtain the modified konjac starch.

[0044] The preparation method of the modified rare earth composite comprises:

[0045] Disperse 100 g of 1,3-bis(2',4'-bis(glycidyl ether)phenyl)adamantane in 1000 ml of anhydrous toluene. Add 45 g of γ-aminopropyltriethoxysilane and 0.5 g of triethylamine under nitrogen protection. Heat to 80°C and reflux for 5 h. After the reaction is complete, cool to room temperature, evaporate to remove the toluene solvent under reduced pressure, and wash with anhydrous ethanol and dry to obtain a modified silane coupling agent.

[0046] 100 g of cerium oxide was dried and dehydrated, then dispersed in 1000 ml of anhydrous toluene and ultrasonically dispersed for 20 minutes. Under nitrogen protection, 20 g of modified silane coupling agent was added, and the temperature was raised to 100° C. and condensed and refluxed for 4 hours. After the reaction was completed, it was filtered, washed, and dried to obtain a modified rare earth composite.

[0047] Example 3

[0048] This embodiment provides a starch adhesive for artificial panels. The adhesive comprises, by weight, 100 parts of modified konjac starch, 25 parts of polyvinyl alcohol, 12 parts of polyacrylate, 0.3 parts of a preservative, 6 parts of epichlorohydrin, 1.0 parts of a viscosity stabilizer, 4 parts of a modified rare earth compound, and 220 parts of water. The preparation method is as follows:

[0049] (1) Add modified konjac starch to deionized water, stir evenly, and gelatinize at 60°C for 40 min to obtain modified konjac starch paste;

[0050] (2) Add polyvinyl alcohol to deionized water to prepare a polyvinyl alcohol solution with a concentration of 20%, cool to room temperature, then add polyacrylate, xanthan gum, potassium sorbate and modified rare earth oxide, stir evenly to obtain a mixed solution;

[0051] (3) The mixed solution was slowly added to the modified konjac starch paste, stirred at 45 °C for 25 min, and then epichlorohydrin was added and stirred for 2 h. The solid content of the adhesive was adjusted to 50% to obtain a starch adhesive.

[0052] The preparation method of the modified konjac starch comprises the following steps: mixing 100 g of konjac starch and 500 ml of water, stirring at room temperature for 30 minutes to fully disperse the mixture, adding 20 g of a 10% sodium hydroxide solution while continuously stirring, adjusting the pH of the solution to alkaline, heating the mixture to 45° C., adding 12 g of a 30% sodium hypochlorite solution, reacting the mixture for 30 minutes, and after the reaction is completed, adjusting the pH to 7.0-7.5 with a 10% dilute hydrochloric acid solution to terminate the oxidation reaction, dialyzing the mixture, concentrating under reduced pressure, drying, and sieving the mixture to obtain the modified konjac starch.

[0053] The preparation method of the modified rare earth composite comprises:

[0054] Disperse 100 g of 1,3-bis(2',4'-bis(glycidyl ether)phenyl)adamantane in 1000 ml of anhydrous toluene. Add 50 g of γ-aminopropyltriethoxysilane and 1.0 g of triethylamine under nitrogen protection. Heat to 85°C and reflux for 3 h. After the reaction is complete, cool to room temperature, evaporate to remove the toluene solvent under reduced pressure, and wash with anhydrous ethanol and dry to obtain a modified silane coupling agent.

[0055] 100 g of cerium oxide was dried and dehydrated, then dispersed in 1000 ml of anhydrous toluene and ultrasonically dispersed for 20 minutes. Under nitrogen protection, 40 g of modified silane coupling agent was added, and the temperature was raised to 120° C. and condensed and refluxed for 3 hours. After the reaction was completed, it was filtered, washed, and dried to obtain a modified rare earth composite.

[0056] Comparative Example 1

[0057] This comparative example provides a starch adhesive for artificial panels. The adhesive comprises, by weight, 100 parts of modified starch, 20 parts of polyvinyl alcohol, 10 parts of polyacrylate, 0.2 parts of potassium sorbate, 4.5 parts of epichlorohydrin, 0.8 parts of xanthan gum, and 200 parts of water. The preparation method is the same as that of Example 1, except that:

[0058] The preparation method of the modified starch includes: mixing 100g of corn starch and 500ml of water, stirring at room temperature for 30 minutes to fully disperse the mixture, adding 18g of a 10% sodium hydroxide solution while stirring continuously, adjusting the pH of the solution to alkaline, heating the solution to 43°C, adding 10g of a 30% sodium hypochlorite solution, reacting the solution for 40 minutes, and after the reaction is completed, adjusting the pH to 7.0-7.5 with a 10% dilute hydrochloric acid solution to terminate the oxidation reaction, dialyzing, concentrating under reduced pressure, drying, and sieving to obtain the modified corn starch.

[0059] Comparative Example 2

[0060] This comparative example provides a starch adhesive for artificial boards. The adhesive comprises, by weight, 100 parts of modified konjac starch, 20 parts of polyvinyl alcohol, 10 parts of polyacrylate, 0.2 parts of potassium sorbate, 4.5 parts of epichlorohydrin, 0.8 parts of xanthan gum, 3 parts of modified rare earth oxide and 200 parts of water. The preparation method is the same as that of Example 1.

[0061] The difference is:

[0062] The preparation method of the modified rare earth composite comprises the following steps: drying and removing water from 100g of cerium oxide, dispersing the mixture in 1000ml of anhydrous toluene, ultrasonically dispersing the mixture for 20 minutes, adding 30g of 1,3-bis(2',4'-bis(glycidyl ether)phenyl)adamantane, stirring and mixing the mixture, removing the toluene solvent by evaporation under reduced pressure, washing the mixture with anhydrous ethanol, and drying the mixture to obtain the modified rare earth composite.

[0063] Comparative Example 3

[0064] This comparative example provides a starch adhesive for artificial panels, which comprises, by weight, 100 parts of modified konjac starch, 20 parts of polyvinyl alcohol, 10 parts of polyacrylate, 0.2 parts of potassium sorbate, 4.5 parts of epichlorohydrin, 0.8 parts of xanthan gum, 3 parts of modified rare earth oxide, and 200 parts of water. The preparation method is the same as that of Example 1, except that:

[0065] The preparation method of the modified rare earth composite comprises: drying and removing water from 100g of cerium oxide, dispersing the mixture in 1000ml of anhydrous toluene, ultrasonically dispersing the mixture for 20 minutes, adding 30g of γ-aminopropyltriethoxysilane under nitrogen protection, heating the mixture to 100°C and condensing and refluxing the mixture for 3.5 hours, filtering, washing and drying the mixture after the reaction is completed to obtain the modified rare earth composite.

[0066] Comparative Example 4

[0067] This comparative example provides a starch adhesive for artificial boards. The adhesive comprises, by weight, 100 parts of konjac starch, 20 parts of polyvinyl alcohol, 10 parts of polyacrylate, 0.2 parts of potassium sorbate, 4.5 parts of epichlorohydrin, 0.8 parts of xanthan gum, 3 parts of modified rare earth complex, and 200 parts of water. The preparation method is the same as that of Example 1, except that the konjac starch is not oxidatively modified.

[0068] Performance testing

[0069] The starch-based adhesives prepared in the Examples and Comparative Examples were tested for performance, including mechanical properties and bond strength. The prepared adhesive samples were pressed into plywood. Bond strength was measured according to the requirements of GB / T17657-2013, "Test Methods for Physical and Chemical Properties of Wood-Based Panels and Veneered Wood-Based Panels." Bonding Performance 1 represents the dry bond strength, Bonding Performance 2 represents the bond strength after immersion in hot water (63°C + 3°C) for 3 hours, and Bonding Performance 3 represents the bond strength after a boil-dry-boil cycle (immersion in boiling water for 4 hours, forced air drying for 16 hours, boiling water immersion for another 4 hours, and finally immersion in cold water for 1 hour). The test results are shown in Table 1.

[0070] Table 1 Bonding strength

[0071]

[0072] As shown in Table 1, the starch adhesive prepared by the technical solution of the embodiment of the present invention has good water resistance and bonding strength.

[0073] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A starch adhesive for artificial boards, characterized by: The adhesive comprises, by weight, 100 parts of modified konjac starch, 15-25 parts of polyvinyl alcohol, 8-12 parts of polyacrylate, 0.1-0.3 parts of preservative, 3-6 parts of epichlorohydrin, 0.5-1.0 parts of viscosity stabilizer, 2-4 parts of modified rare earth compound and 180-220 parts of water.

2. The starch adhesive for artificial boards according to claim 1, wherein: The preparation method of the modified konjac starch comprises: mixing konjac starch and water, adding 10% sodium hydroxide solution under continuous stirring, heating to 40-45° C., adding 30% sodium hypochlorite solution, and reacting for 30-50 minutes to obtain the modified konjac starch.

3. The starch adhesive for artificial boards according to claim 2, wherein: The mass ratio of the konjac starch, the sodium hydroxide solution and the sodium hypochlorite solution is 100:15-20:8-12.

4. The starch adhesive for artificial boards according to claim 1, wherein: The preparation method of the modified rare earth composite comprises: Disperse 1,3-bis(2',4'-bis(glycidyl ether)phenyl)adamantane in anhydrous toluene, add γ-aminopropyltriethoxysilane and triethylamine under nitrogen protection, raise the temperature to 80-85°C, and react for 3-5 hours to obtain a modified silane coupling agent; The rare earth oxide is dispersed in anhydrous toluene, and a modified silane coupling agent is added under nitrogen protection. The temperature is raised to 100-120° C., and the mixture is condensed and refluxed for 3-4 hours to obtain a modified rare earth composite.

5. The starch adhesive for artificial boards according to claim 4, characterized in that: The mass ratio of the 1,3-bis(2',4'-bis(glycidyl ether)phenyl)adamantane, γ-aminopropyltriethoxysilane and triethylamine is 100:45-50:0.5-1.

0.

6. The starch adhesive for artificial boards according to claim 4, characterized in that: The rare earth oxide is cerium oxide and / or lanthanum oxide.

7. The starch adhesive for artificial boards according to claim 4, wherein: The mass ratio of the rare earth oxide to the modified silane coupling agent is 10:2-4.

8. The starch adhesive for artificial boards according to claim 1, wherein: The preservative is one or more of sodium benzoate, potassium sorbate or calcium propionate.

9. The starch adhesive for artificial boards according to claim 1, wherein: The viscosity stabilizer is one or more of sodium carboxymethyl cellulose, xanthan gum or guar gum.

10. The method for preparing a starch adhesive for artificial panels according to any one of claims 1 to 9, wherein: The following steps are involved: (1) Add modified konjac starch to deionized water, stir evenly, and gelatinize at 60°C for 30-40 min to obtain modified konjac starch paste; (2) adding polyvinyl alcohol to deionized water to prepare a polyvinyl alcohol solution with a concentration of 15-20%, cooling to room temperature, then adding polyacrylate, preservative, viscosity stabilizer and modified rare earth oxide, stirring evenly to obtain a mixed solution; (3) Slowly add the mixed solution into the modified konjac starch paste, stir and mix at 35-45°C for 15-25 minutes, then add epichlorohydrin and continue stirring for 2-3 hours to obtain a starch adhesive.

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