Method for preparing bamboo gluing material through host-guest molecule recognition principle and product

Abstract

The invention discloses a method for preparing a bamboo gluing material through a host-guest molecule recognition principle and a product, belongs to the technical field of bamboo composite materials, and particularly discloses a biomass adhesive which is an AC-O beta-CD adhesive and a method for preparing the bamboo gluing material by using the biomass adhesive. The specific preparation method comprises the following steps that after the surface of an activated bamboo object is in lap joint, hot-pressing curing is conducted, a subject-object molecular recognition supramolecular interface is constructed between the surface of the activated bamboo object and a biomass adhesive subject, and then the bamboo gluing material is obtained. The invention further discloses the bamboo gluing material prepared by the method. The raw materials used in the invention do not contain volatile substances harmful to human bodies, the adhesive is a green and environment-friendly novel adhesive, only water is needed as a solvent in the preparation process, a one-pot method is adopted, the operation is simple, a reaction product does not need to be separated and purified, and the storage period is long.

Description

Technical Field

[0001] The invention belongs to the technical field of bamboo composite materials, and in particular relates to a method and product for preparing bamboo adhesive materials through the host-guest molecule recognition principle. Background Art

[0002] With the rapid development of the real estate industry, building decoration industry, home furnishing industry and the significant improvement of people's living standards, the rapid development of composite materials such as wood and bamboo, the consumption of adhesives is also increasing year by year. Bamboo grows rapidly and is rich in resources. It has excellent properties such as high strength, high hardness, good impact toughness and good wear resistance. It is considered to be the most promising material in nature in terms of strength and cost, and is widely used as a building material.

[0003] Currently, the existing adhesives for wood and bamboo materials usually include formaldehyde adhesives, polyurethane adhesives, and the currently popular biomass adhesives. The bonding principle is mainly to provide cohesive force through the adhesive polymer structure itself, and at the same time, the adhesive and the bonded substrate are bonded through physical mechanical interlocking or interfacial chemistry (including covalent and non-covalent interactions, etc.). However, most biomass adhesives have problems such as poor bonding performance and poor water resistance. Therefore, how to solve these defects is the primary issue that needs to be paid attention to in the industry.

[0004] In this context, the development of green, environmentally friendly, and high-performance biomass composites has become a hot topic in the industry. More and more researchers are exploring and applying supramolecular adhesives with non-covalent interactions, such as hydrogen bonding, ion pairing, hydrophobic effects, metal ligand complexation, π-π stacking, etc. However, there are few reports on the technology of achieving high-performance bonding of wood or bamboo through molecular recognition between macrocyclic supramolecular hosts and guests. Summary of the invention

[0005] In order to solve the above technical problems, the present invention proposes a method and product for preparing bamboo adhesive material by using the host-guest molecule recognition principle.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] The first aspect of the present invention is to provide a biomass adhesive, wherein the biomass adhesive is AC-Oβ-CD adhesive, and the preparation method thereof comprises the following steps:

[0008] The aminated cellulose is dispersed in a NaOH solution and then frozen. Then, oxidized cyclodextrin is added and heated for reaction. The pH is adjusted to a weak alkaline state. The reaction is continued until the color becomes darker and then cooled. The reaction is completed to obtain the AC-Oβ-CD adhesive.

[0009] Compared with the prior art, the technical effect of the present invention is that cyclodextrin (CDs), as one of the most important participants in supramolecular chemistry, has attracted widespread attention as a valuable natural or synthetic modified cyclooligosaccharide in the past few decades. The bioadhesive of the present invention uses cyclodextrin as a matrix, which is first oxidized to form oxidized cyclodextrin, so that part of the hydroxyl groups in the cyclodextrin are oxidized to aldehyde groups, and then the aldehyde groups react with the amino groups on the aminated fibers to form a stable imine bond, so that the oxidized cyclodextrin is grafted on both sides of the chain of the aminated fibers. Oxidized cyclodextrin has a hydrophilic outer surface, which promotes interaction with surrounding molecules through hydrogen bonds, and the hydrophobic cavity can accommodate various hydrophobic guests, forming a host-guest inclusion body in an aqueous environment or even in a solid state, thereby achieving high-performance bonding of wood or bamboo.

[0010] Preferably, the aminated cellulose is obtained by subjecting microcrystalline cellulose to two-step substitution reactions with thionyl chloride and ethylenediamine; and the oxidized cyclodextrin is obtained by oxidizing β-cyclodextrin with sodium periodate.

[0011] Preferably, the mass ratio of the oxidized cyclodextrin to the aminated cellulose is 1:1-1.5.

[0012] Preferably, the temperature of the heating reaction is 95°C; the temperature after cooling is 70°C

[0013] Preferably, the pH is adjusted to 8 using glacial acetic acid.

[0014] The second aspect of the present invention is to provide a method for preparing a bamboo adhesive material through the host-guest molecular recognition principle, wherein the activated bamboo guest surface is overlapped with the biomass adhesive prepared above, and then hot-pressed and cured to construct a host-guest molecular recognition supramolecular interface between the activated bamboo guest surface and the biomass adhesive body, thereby obtaining the bamboo adhesive material.

[0015] Preferably, the activated bamboo object is obtained by soaking bamboo in a toluene solution of 3-aminopropyltriethoxysilane and adamantane acid chloride.

[0016] Preferably, in the toluene solution of 3-aminopropyltriethoxysilane and adamantane acyl chloride, the concentration of 3-aminopropyltriethoxysilane is 2.5×10 -3 ~5×10 -3 mol / mL, the concentration of adamantane chloride is 1×10 -3 ~2×10 -3 The present invention realizes the grafting with bamboo material through the hydrolysis condensation of silane coupling agent, and the concentration range of the reagent used is just right, and the grafting rate will not be reduced due to too low concentration, and will not be wasted due to oversaturation.

[0017] Preferably, the soaking time is 18-36 hours, within which the guest molecules can be fully grafted on the surface of the substrate, while the performance of the bamboo material itself will not be damaged due to soaking for too long.

[0018] Preferably, the amount of the biomass adhesive applied to the surface of the activated bamboo object is 180-220 g / m 2 The amount of glue applied within this range will not lead to poor bonding performance due to too little glue applied, nor will it cause waste due to too much glue applied.

[0019] Preferably, the temperature of the hot pressing curing is 140-200°C, the time is 5-8 minutes, and the pressure is 2-4 MPa. The curing temperature and pressure conditions in this range are similar to the curing conditions in the industry at present, which is conducive to future industrial production applications.

[0020] The third aspect of the present invention is to provide a bamboo adhesive material prepared by a method for preparing a bamboo adhesive material by the host-guest molecular recognition principle.

[0021] Compared with the prior art, the present invention has the following advantages and technical effects:

[0022] The bamboo composite material prepared by the present invention solves the technical problem of how to graft supramolecular compounds on the surface of bamboo and enhance the bonding performance by constructing a host-guest recognition bonding system, and provides a specific preparation process of supramolecular adhesive and supramolecular functionalized bamboo. The present invention realizes the molecular recognition interface between the subject and the guest, forms an inclusion compound, increases the interaction between the adhesive and the matrix during the bonding process, and effectively improves the performance of the biomass adhesive, such as poor bonding performance and poor water resistance. In addition, compared with the composite material produced by traditional aldehyde adhesives, the bamboo composite material prepared by the present invention does not contain formaldehyde addition and is harmless to the human body. The raw materials used in the present invention do not contain any volatilization of substances harmful to the human body, and are a new type of green and environmentally friendly adhesive. In the preparation process, only water is needed as a solvent, a one-pot method is adopted, the operation is simple, the reaction product does not need to be separated and purified, and the storage period is long. The present invention embodies the principles of environmental protection and sustainable development, and is simple to operate, which is conducive to industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0024] Figure 1 Schematic diagram of the preparation process of activating the surface of the bamboo object in Example 1 of the present invention;

[0025] Figure 2The preparation principle of oxidized cyclodextrin (Oβ-CD) in the embodiment of the present invention;

[0026] Figure 3 The preparation of aminated cellulose (AC) in the embodiment of the present invention;

[0027] Figure 4 The adhesive body with C=N bond is generated by reacting the aminated cellulose (AC) and the oxidized cyclodextrin (Oβ-CD) in Example 1 of the present invention;

[0028] Figure 5 Schematic diagram of the host-guest recognition bonding interface in Example 1 of the present invention. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments 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 creative work are within the scope of protection of the present invention.

[0030] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] The embodiment of the present invention provides a method for preparing a bamboo adhesive material by using the host-guest molecular recognition principle. After the activated bamboo guest surface is overlapped with a biomass adhesive, hot pressing and curing are performed to construct a host-guest molecular recognition supramolecular interface between the activated bamboo guest surface and the biomass adhesive body, thereby obtaining the bamboo adhesive material.

[0032] In a preferred embodiment, the activated bamboo object is obtained by soaking bamboo in a toluene solution of 3-aminopropyltriethoxysilane and adamantane acid chloride.

[0033] In a preferred embodiment, the concentration of 3-aminopropyltriethoxysilane in the toluene solution of 3-aminopropyltriethoxysilane and adamantane acyl chloride is 2.5×10 -3 ~5×10 -3 mol / mL, the concentration of adamantane chloride is 1×10 -3 ~2×10 -3 mol / mL.

[0034] In a preferred embodiment, the soaking time is 18-36 hours.

[0035] In a preferred embodiment, the biomass adhesive is AC-Oβ-CD adhesive, and its preparation method comprises the following steps:

[0036] The aminated cellulose is dispersed in a NaOH solution and then frozen. Then, oxidized cyclodextrin is added and heated at 95° C. for reaction. The pH is adjusted and the reaction is continued. Finally, the reaction is carried out at 70° C. until the reaction is complete, thereby obtaining the AC-Oβ-CD adhesive.

[0037] In a preferred embodiment, the aminated cellulose is obtained by two-step substitution reaction of microcrystalline cellulose with thionyl chloride and ethylenediamine;

[0038] The oxidized cyclodextrin is obtained by oxidizing β-cyclodextrin using sodium periodate.

[0039] In a preferred embodiment, the mass ratio of the oxidized cyclodextrin to the aminated cellulose is 1:1-1.5;

[0040] In a more preferred embodiment, the mass ratio of the oxidized cyclodextrin to the aminated cellulose is 1:1, 1:1.25 or 1:1.5.

[0041] In a preferred embodiment, the pH is adjusted to 8 using glacial acetic acid.

[0042] In a preferred embodiment, the temperature of the hot pressing curing is 140-200° C., the time is 5-8 min, and the pressure is 2-4 MPa.

[0043] In a preferred embodiment, the amount of the biomass adhesive applied to the surface of the activated bamboo object is 180-220 g / m 2 .

[0044] The embodiment of the present invention also provides a bamboo adhesive material prepared by a method for preparing a bamboo adhesive material by using a host-guest molecule recognition principle.

[0045] Unless otherwise specified, the room temperature or normal temperature in the embodiments of the present invention refers to 25±3°C.

[0046] Unless otherwise specified, the raw materials in the examples of the present invention were purchased from commercial sources;

[0047] The bamboo was purchased from the local market, and the green and yellow parts of the bamboo had been removed when it was purchased.

[0048] Oxidized cyclodextrin (Oβ-CD) is obtained by oxidizing β-cyclodextrin with sodium periodate. The preparation principle is as follows: Figure 2 shown.

[0049] Aminated cellulose (AC) is obtained by two-step substitution reaction of microcrystalline cellulose with thionyl chloride and ethylenediamine. The preparation principle is as follows: Figure 3 shown.

[0050] Example 1

[0051] A method for preparing a bamboo adhesive material by using the host-guest molecular recognition principle comprises the following steps:

[0052] (1) Figure 1 As shown, bamboo was placed in a solution containing 2.5 mmol (0.58 mL) of APTES and AdCACl (1 × 10 -3 M) in a toluene (50 mL) solution at room temperature for 24 h, then the soaked bamboo was rinsed with deionized water and ethanol, and dried at room temperature to obtain an activated bamboo guest surface;

[0053] (2) Disperse 5g AC into 40g NaOH solution with a concentration of 7wt% and freeze. Then, add 4g oxidized cyclodextrin (Oβ-CD) and AC after freeze-thaw into a round-bottom flask (the mass ratio of Oβ-CD to AC is 1:1.25), react in a 95℃ oil bath for about 30min, adjust the pH to 8 with glacial acetic acid, and continue to react for about 30min. When the color of the reactant turns dark brown, cool it to 70℃ and continue to react for 10h to ensure the complete reaction, and obtain AC-Oβ-CD adhesive. The reaction principle is as follows: Figure 4 As shown;

[0054] (3) The AC-Oβ-CD adhesive obtained in step (2) was evenly applied on one side of the activated bamboo object surface (20 mm×20 mm) obtained in step (1), with an amount of about 220 g / m 2 The bonding area is overlapped by hot pressing to obtain a bamboo adhesive material. The hot pressing conditions are a hot pressing temperature of 140°C, a hot pressing pressure of 2MPa, and a hot pressing time of 360s. The schematic diagram of the host-guest recognition bonding interface formed after hot pressing is shown in Figure 5 shown.

[0055] Example 2

[0056] A method for preparing a bamboo adhesive material by using the host-guest molecular recognition principle, which is different from Example 1 only in that the hot pressing temperature in step (3) is 160° C., and the remaining process steps and parameters are the same as those in Example 1.

[0057] Example 3

[0058] A method for preparing a bamboo adhesive material by using the host-guest molecular recognition principle, which is different from Example 1 only in that the hot pressing temperature in step (3) is 180° C., and the remaining process steps and parameters are the same as those in Example 1.

[0059] Example 4

[0060] A method for preparing a bamboo adhesive material by using the host-guest molecular recognition principle, which is different from Example 1 only in that the hot pressing temperature in step (3) is 200° C., and the remaining process steps and parameters are the same as those in Example 1.

[0061] Example 5

[0062] A method for preparing a bamboo adhesive material by the host-guest molecular recognition principle, which is different from Example 1 only in that in step (2), 5 g of oxidized cyclodextrin (Oβ-CD) and AC after freeze-thaw are added to a round-bottom flask (the mass ratio of Oβ-CD to AC is 1:1);

[0063] The hot pressing temperature in step (3) is 160° C., and the remaining process steps and parameters are the same as those in Example 1.

[0064] Example 6

[0065] A method for preparing a bamboo adhesive material by host-guest molecular recognition principle, which is different from Example 1 only in that in step (2), 3.33 g of oxidized cyclodextrin (Oβ-CD) and AC after freeze-thaw are added to a round-bottom flask (the mass ratio of Oβ-CD to AC is 1:1.5);

[0066] The hot pressing temperature in step (3) is 160° C., and the remaining process steps and parameters are the same as those in Example 1.

[0067] Comparative Examples 1-6

[0068] A method for preparing a bamboo composite material, wherein the surface of an activated bamboo object is replaced by the surface of a raw bamboo material, and the remaining process steps and parameters are respectively the same as those of Examples 1-6.

[0069] The physical and mechanical properties of the composite materials were tested using a universal mechanical testing machine, and the lap shear strength of the bamboo composite materials was tested according to GB / T17657-2013 standard. Gluing strength 1 is the dry bonding strength, bonding strength 2 is the bonding strength after immersion in hot water (63±2℃) for 3 hours, and bonding strength 3 is the bonding strength after immersion in boiling water for 3 hours. The results are shown in Table 1.

[0070] Table 1 Glue strength table

[0071]

[0072]

[0073] It can be seen from Table 1 that under non-optimal conditions, not only the host-guest recognition bonding interface will affect the bonding performance, but other factors also have a significant impact on the bonding performance. The final bonding strength is affected by multiple factors. Although the bonding strength of Examples 1, 5, and 6 is less improved, it is still improved to a certain extent. The comparison shows that the host-guest recognition has an enhancing effect on the bonding performance. In addition, as the temperature increases from 140°C (Example 1) to 200°C (Example 4), the bonding performance also increases, which shows the important influence of temperature on the bonding performance. Examples 4, 5, and 6 explored the mass ratio of Oβ-CD to AC in the adhesive component. By comparing the data in Table 1, it is shown that the bonding performance is best when the mass ratio of Oβ-CD to AC is 1:1.25, and the adhesive ratio has a significant effect on the bonding performance. This is because when the mass ratio of Oβ-CD to AC is too low, the grafting rate of the main cyclodextrin molecules is low, so the host-guest recognition effect between the adhesive and the substrate is relatively small, resulting in low bonding strength; when the mass ratio of Oβ-CD to AC is too high, in addition to the Oβ-CD that reacts with AC, there will be a part of Oβ-CD in a free state, which will also undergo host-guest recognition with the substrate, and will be in a competitive relationship with the main body in the adhesive, reducing the interaction between the adhesive and the substrate, thereby reducing the bonding performance. In summary, the best experiment is the bamboo adhesive material with a supramolecular interface constructed in Example 4, and its dry strength reaches 15.74 MPa, which is 13.68 MPa higher than 2.06 MPa of the bamboo adhesive material without a supramolecular interface constructed under the same conditions (Comparative Example 4). The strength is about 7.6 times that of the bamboo adhesive material without a supramolecular interface constructed. By comparing other embodiments with the corresponding comparative examples, it can be concluded that the construction of the supramolecular interface in the embodiments of the present invention can greatly improve the bonding strength of the bamboo adhesive material.

[0074] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A bioadhesive, characterized in that: The biomass adhesive is AC-Oβ-CD adhesive, and its preparation method comprises the following steps: The aminated cellulose is dispersed in a NaOH solution and then frozen, and then oxidized cyclodextrin is added and heated for reaction, and then the pH is adjusted to weak alkalinity, and the reaction is continued until the color becomes darker, and then cooled, and the reaction is continued until completion, so as to obtain the AC-Oβ-CD adhesive.

2. The bioadhesive according to claim 1, characterized in that The aminated cellulose is obtained by subjecting microcrystalline cellulose to two-step substitution reactions of thionyl chloride and ethylenediamine; The oxidized cyclodextrin is obtained by oxidizing β-cyclodextrin using sodium periodate.

3. The bioadhesive according to claim 1, characterized in that: The mass ratio of the oxidized cyclodextrin to the aminated cellulose is 1:1-1.

5.

4. The bioadhesive according to claim 1, characterized in that: The temperature of the heating reaction is 95°C; the temperature after cooling is 70°C.

5. The bioadhesive according to claim 1, characterized in that: The pH is adjusted to 8 using glacial acetic acid.

6. A method for preparing bamboo adhesive material by host-guest molecular recognition principle, characterized in that: The activated bamboo guest surface is overlapped with the biomass adhesive described in any one of claims 1 to 5, and then hot-pressed and cured to construct a host-guest molecular recognition supramolecular interface between the activated bamboo guest surface and the biomass adhesive body, thereby obtaining the bamboo adhesive material.

7. The method for preparing bamboo adhesive material by host-guest molecular recognition principle according to claim 6, characterized in that: The activated bamboo guest surface is obtained by soaking the bamboo in a toluene solution of 3-aminopropyltriethoxysilane and adamantane acyl chloride.

8. The method for preparing bamboo adhesive material by host-guest molecular recognition principle according to claim 7, characterized in that: In the toluene solution of 3-aminopropyltriethoxysilane and adamantane acyl chloride, the concentration of 3-aminopropyltriethoxysilane is 2.5×10 -3 ~5×10 -3 mol / mL, the concentration of adamantane chloride is 1×10 -3 ~2×10 -3 mol / mL.

9. The method for preparing bamboo adhesive material by host-guest molecular recognition principle according to claim 6, characterized in that: The temperature of the hot pressing curing is 140-200° C., the time is 5-8 min, and the pressure is 2-4 MPa.

10. The bamboo adhesive material prepared by the method for preparing bamboo adhesive material by host-guest molecular recognition principle as claimed in any one of claims 6 to 9.

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