Environmentally friendly glue for children's picture books based on natural plant extracts, preparation method and application thereof

Abstract

The present invention relates to the technical field of adhesives, and in particular to an environmentally friendly glue for children's picture books based on natural plant extracts, and a preparation method and application thereof. The glue comprises the following components: 10-15 parts by weight of loofah extract, 45-55 parts by weight of dynamic network base liquid, 0.5-1.5 parts by weight of xanthan gum, 1.2-2.3 parts by weight of nanocellulose, 0.3-0.6 parts by weight of methylcellulose, 2-4 parts by weight of aloe vera gel, 1-2 parts by weight of glycerol, 2-4 parts by weight of sorbitol, and 0.3-0.7 parts by weight of rosemary extract; wherein the dynamic network base liquid is obtained by mixing oxidized konjac glucomannan, silk fibroin, tannic acid, and ferric chloride. The present invention adopts a dynamic multiple cross-linked network design, forms a dynamic covalent bond by oxidizing konjac glucomannan and silk fibroin, combines tannic acid-Fe³⁺ coordination complexation, and constructs a three-dimensional network with a synergistic effect of dynamic covalent bonds and coordination bonds.

Description

Technical Field

[0001] The present invention relates to the technical field of adhesives, in particular to environmentally friendly glue for children's picture books based on natural plant extracts, and a preparation method and application thereof. Background Art

[0002] Publication No. CN1944560A discloses a glue for environmentally friendly pressure-sensitive adhesive composite materials and its preparation method. The patent document optimizes the formula and selects appropriate components and proportions to greatly improve its performance. Its components include octyl ester, butyl ester, acrylic acid, light ethyl ester, vinyl acetate, ammonium peroxide and ammonium carbonate. The glue has stable initial and sustained adhesion, good peeling performance, no irritating odor, and good environmental protection. However, the glue protected by the above-mentioned patent document, like traditional synthetic glue, contains harmful substances such as volatile organic compounds (VOCs) and formaldehyde, and long-term use poses health and environmental pollution risks. In recent years, environmental protection and health awareness have been enhanced, and natural plant extracts (such as guar gum, locust bean gum, and sesbania gum) have become a research hotspot again due to their non-toxic and biodegradable properties. Through modern extraction and modification technologies, plant-based glues have achieved performance optimization while retaining their environmental advantages. However, the existing environmentally friendly glue for children's picture books is prone to brittle fracture during children's use due to shear force generated by frequent page turning, which leads to a decrease in bonding strength. In view of this, we propose an environmentally friendly glue for children's picture books based on natural plant extracts, as well as a preparation method and application thereof. Summary of the Invention

[0003] The purpose of the present invention is to provide an environmentally friendly glue for children's picture books based on natural plant extracts, and a preparation method and application thereof, so as to solve the problems raised in the above background technology.

[0004] To achieve the above objectives, the present invention provides an environmentally friendly glue for children's picture books based on natural plant extracts, comprising the following components: 10-15 parts by weight of loofah extract, 45-55 parts by weight of dynamic network base liquid, 0.5-1.5 parts by weight of xanthan gum, 1.2-2.3 parts by weight of nanocellulose, 0.3-0.6 parts by weight of methylcellulose, 2-4 parts by weight of aloe vera gel, 1-2 parts by weight of glycerin, 2-4 parts by weight of sorbitol, and 0.3-0.7 parts by weight of rosemary extract;

[0005] The dynamic network base liquid is obtained by mixing oxidized konjac glucomannan, silk fibroin, tannic acid and ferric chloride.

[0006] Oxidized konjac glucomannan, silk fibroin, tannic acid and ferric chloride are introduced to form a dynamic network. Due to the presence of aldehyde and carboxyl groups in oxidized konjac glucomannan, the aldehyde groups form a Schiff base (-CH=N-) structure with the amino groups in the silk fibroin. This reaction is a dynamic covalent bond with a certain degree of reversibility. At the same time, the carboxyl groups of oxidized konjac glucomannan can form chemical bonds with the iron ions in the ferric chloride, and the multiple ortho-phenolic hydroxyl groups of tannic acid can act as ligands to complex with the iron ions to form a dynamic coordination network. Therefore, silk fibroin serves as a cross-linking carrier, the complex of tannic acid and iron ions, and oxidized konjac glucomannan serve as cross-linking and bridging, integrating dynamic covalent bonds and dynamic coordination bonds to achieve multiple cross-linking, which jointly promote the formation of a complex dynamic three-dimensional network, adapting to the repeated opening and closing of children's picture books and extending their service life.

[0007] Preferably, the specific preparation steps of the loofah extract are:

[0008] The dried loofah was mechanically crushed to a particle size of 0.5-1 mm, and defatted with 70-75% ethanol at 60-65°C for 2-3 h to obtain defatted loofah. The defatted loofah was mixed with 2-3 mol / L NaOH solution at a mass ratio of 1:13-15, refluxed at 85-90°C for 3-4 h, and centrifuged. The supernatant was refluxed with acetic acid and hydrochloric acid at a volume ratio of 9:1 at 70-75°C for 2-3 h. The precipitate was washed with water until neutral, freeze-dried, and reacted with sodium sulfite at 120-125°C for 2-3 h to obtain the loofah extract.

[0009] Since the bonding property of oxidized konjac glucomannan is weaker than that of traditional glue base materials, loofah extract is added to further compensate for the initial bonding strength. In addition, loofah extract has the ability to coordinate with Fe³⁺, which can enhance the stability of the dynamic cross-linked network.

[0010] Preferably, the mass ratio of the precipitate to sodium sulfite is 1:0.3-0.5.

[0011] Preferably, the preparation method of the dynamic network base liquid is as follows:

[0012] Oxidized konjac glucomannan is dissolved in deionized water to obtain an oxidized konjac glucomannan solution. After adding silk fibroin to the oxidized konjac glucomannan solution, the pH is adjusted to 8.5-9.0, and the mixture is stirred at 40-50°C for 1-2 hours. Then, tannic acid is added and stirred to mix evenly. 0.5-1 mol / L ferric chloride solution is added dropwise, and the mixture is stirred at room temperature for 20-30 minutes to obtain a dynamic network base liquid. The residual Fe³⁺ content is detected by inductively coupled plasma mass spectrometry, and the residual Fe³⁺ content is removed and the final free Fe³⁺ residue does not exceed 70 mg / kg to ensure that the glue meets the safety standards for children's products.

[0013] Preferably, the mass fraction of the oxidized konjac glucomannan solution is 5-8%.

[0014] Preferably, the mass ratio of the oxidized konjac glucomannan to silk fibroin is 1:0.3-0.5.

[0015] Preferably, the mass ratio of the oxidized konjac glucomannan to tannic acid is 1:0.1-0.2.

[0016] Preferably, the molar ratio of the tannic acid to the ferric chloride is 2 to 4:1.

[0017] On the other hand, the present invention provides a method for preparing an environmentally friendly glue for children's picture books based on natural plant extracts, which is used to prepare the environmentally friendly glue for children's picture books based on natural plant extracts, comprising the following steps:

[0018] The dynamic network base liquid is mixed with the loofah extract, and the mixture is homogenized at a high speed of 8000-9000 rpm at 60°C for 15-20 minutes. Xanthan gum, nanocellulose and methylcellulose are added in sequence and stirred at 40-45°C until there are no particles. Glycerin, aloe vera gel, sorbitol and rosemary extract are added, and the pH is adjusted to 6.5-7.5. The mixture is vacuum homogenized at -0.08 MPa for 25-30 minutes for degassing. The mixture is sieved through a 200-mesh sieve and then filled and sealed to obtain an environmentally friendly glue for children's picture books based on natural plant extracts.

[0019] The present invention also provides an application of an environmentally friendly glue for children's picture books based on natural plant extracts, including the environmentally friendly glue for children's picture books based on natural plant extracts prepared by the above-mentioned preparation method of the environmentally friendly glue for children's picture books based on natural plant extracts, and the environmentally friendly glue for children's picture books based on natural plant extracts is used for bonding picture books to paper materials.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] This environmentally friendly glue for children's picture books based on natural plant extracts, as well as its preparation method and application, adopts a dynamic multiple cross-linking network design, forms dynamic covalent bonds between oxidized konjac glucomannan and silk fibroin, and combines tannic acid-Fe³⁺ coordination complexation to construct a three-dimensional network with synergistic effects of dynamic covalent bonds and coordination bonds. This structure is both reversible and stable, giving the glue self-repairing ability, adapting to the use scenario of repeated opening and closing of picture books. Luffa extract is used to retain phenolic hydroxyl groups and introduce sulfonic acid groups, which not only enhances the dynamic network stability through Fe³⁺ coordination, but also makes up for the insufficient initial bonding strength of oxidized konjac glucomannan, achieving performance complementarity. Plant-derived ingredients such as luffa, aloe vera gel, and rosemary extract are used to avoid harmful substances such as formaldehyde and benzene series in traditional glues, which meets the safety standards for children's products. DETAILED DESCRIPTION

[0022] 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.

[0023] The environmentally friendly glue for children's picture books based on natural plant extracts of the present invention comprises the following components: 10-15 parts by weight of loofah extract, 45-55 parts by weight of dynamic network base liquid, 0.5-1.5 parts by weight of xanthan gum, 1.2-2.3 parts by weight of nanocellulose, 0.3-0.6 parts by weight of methylcellulose, 2-4 parts by weight of aloe vera gel, 1-2 parts by weight of glycerin, 2-4 parts by weight of sorbitol, and 0.3-0.7 parts by weight of rosemary extract;

[0024] The dynamic network base liquid is obtained by mixing oxidized konjac glucomannan, silk fibroin, tannic acid and ferric chloride;

[0025] The main active ingredients in rosemary extract include terpenoids (monoterpenes, sesquiterpenes, diterpenes), phenolic acid compounds (rosmarinic acid and its derivatives), flavonoids (luteolin and its glycosides, apigenins) and volatile oils (α-pinene, β-pinene).

[0026] Example 1: Environmentally friendly glue for children's picture books based on natural plant extracts, and its preparation method and application, comprising the following steps:

[0027] Prepare the following components: 10 parts by weight of loofah extract, 45 parts by weight of dynamic network base liquid, 1.5 parts by weight of xanthan gum, 2.3 parts by weight of nanocellulose, 0.6 parts by weight of methylcellulose, 4 parts by weight of aloe vera gel, 2 parts by weight of glycerin, 4 parts by weight of sorbitol, and 0.7 parts by weight of rosemary extract;

[0028] The dynamic network base liquid is obtained by mixing oxidized konjac glucomannan, silk fibroin, tannic acid and ferric chloride;

[0029] The dried loofah was mechanically crushed to a particle size of 0.5 mm, and defatted with 70% ethanol at 60°C for 2 h to obtain defatted loofah. The defatted loofah was mixed with 2 mol / L NaOH solution at a mass ratio of 1:15, refluxed at 90°C for 3 h, and centrifuged. The supernatant was refluxed with acetic acid and hydrochloric acid at a volume ratio of 9:1 at 70°C for 2 h. The precipitate was washed with water until neutral, freeze-dried, and reacted with sodium sulfite at a mass ratio of 1:0.5 at 120°C for 2 h to obtain the loofah extract.

[0030] Oxidized konjac glucomannan was dissolved in deionized water to obtain a 5% oxidized konjac glucomannan solution. Silk fibroin was added to the oxidized konjac glucomannan solution at a mass ratio of 1:0.3, the pH was adjusted to 9.0, and the mixture was stirred at 50°C for 1 hour. Tannic acid was then added and stirred to mix evenly. 0.5 mol / L ferric chloride solution was added dropwise at a mass ratio of 1:0.1 between oxidized konjac glucomannan and tannic acid, and the molar ratio of tannic acid to ferric chloride was 3:1. The mixture was stirred at room temperature for 30 minutes to obtain a dynamic network base solution.

[0031] The dynamic network base liquid was mixed with the loofah extract, and the mixture was homogenized at 8000 rpm at 60°C for 15 min. Xanthan gum, nanocellulose and methylcellulose were added in sequence and stirred at 45°C until there were no particles. Glycerin, aloe vera gel, sorbitol and rosemary extract were added, and the pH was adjusted to 7.0. The mixture was homogenized in a vacuum at -0.08 MPa for 30 min for degassing. The mixture was passed through a 200-mesh sieve and then filled and sealed to obtain an environmentally friendly glue for children's picture books based on natural plant extracts.

[0032] Example 2: Environmentally friendly glue for children's picture books based on natural plant extracts, and its preparation method and application, comprising the following steps:

[0033] Prepare the following components: 10 parts by weight of loofah extract, 50 parts by weight of dynamic network base liquid, 1.5 parts by weight of xanthan gum, 2.3 parts by weight of nanocellulose, 0.6 parts by weight of methylcellulose, 4 parts by weight of aloe vera gel, 2 parts by weight of glycerin, 4 parts by weight of sorbitol, and 0.7 parts by weight of rosemary extract;

[0034] The dynamic network base liquid is obtained by mixing oxidized konjac glucomannan, silk fibroin, tannic acid and ferric chloride;

[0035] The dried loofah was mechanically crushed to a particle size of 0.5 mm, and defatted with 70% ethanol at 60°C for 2 h to obtain defatted loofah. The defatted loofah was mixed with 2 mol / L NaOH solution at a mass ratio of 1:15, refluxed at 90°C for 3 h, and centrifuged. The supernatant was refluxed with acetic acid and hydrochloric acid at a volume ratio of 9:1 at 70°C for 2 h. The precipitate was washed with water until neutral, freeze-dried, and reacted with sodium sulfite at a mass ratio of 1:0.5 at 120°C for 2 h to obtain the loofah extract.

[0036] Oxidized konjac glucomannan was dissolved in deionized water to obtain a 5% oxidized konjac glucomannan solution. Silk fibroin was added to the oxidized konjac glucomannan solution at a mass ratio of 1:0.4, the pH was adjusted to 9.0, and the mixture was stirred at 50°C for 1 hour. Tannic acid was then added and stirred to mix evenly. Oxidized konjac glucomannan and tannic acid were mixed at a mass ratio of 1:0.15, and 0.5 mol / L ferric chloride solution was added dropwise. The molar ratio of tannic acid to ferric chloride was 3:1. The mixture was stirred at room temperature for 30 minutes to obtain a dynamic network base liquid.

[0037] The dynamic network base liquid was mixed with the loofah extract, and the mixture was homogenized at 8000 rpm at 60°C for 15 min. Xanthan gum, nanocellulose and methylcellulose were added in sequence and stirred at 45°C until there were no particles. Glycerin, aloe vera gel, sorbitol and rosemary extract were added, and the pH was adjusted to 7.0. The mixture was homogenized in a vacuum at -0.08 MPa for 30 min for degassing. The mixture was passed through a 200-mesh sieve and then filled and sealed to obtain an environmentally friendly glue for children's picture books based on natural plant extracts.

[0038] Example 3: Environmentally friendly glue for children's picture books based on natural plant extracts, and its preparation method and application, comprising the following steps:

[0039] Prepare the following components: 10 parts by weight of loofah extract, 55 parts by weight of dynamic network base liquid, 1.5 parts by weight of xanthan gum, 2.3 parts by weight of nanocellulose, 0.6 parts by weight of methylcellulose, 4 parts by weight of aloe vera gel, 2 parts by weight of glycerin, 4 parts by weight of sorbitol, and 0.7 parts by weight of rosemary extract;

[0040] The dynamic network base liquid is obtained by mixing oxidized konjac glucomannan, silk fibroin, tannic acid and ferric chloride;

[0041] The dried loofah was mechanically crushed to a particle size of 0.5 mm, and defatted with 70% ethanol at 60°C for 2 h to obtain defatted loofah. The defatted loofah was mixed with 2 mol / L NaOH solution at a mass ratio of 1:15, refluxed at 90°C for 3 h, and centrifuged. The supernatant was refluxed with acetic acid and hydrochloric acid at a volume ratio of 9:1 at 70°C for 2 h. The precipitate was washed with water until neutral, freeze-dried, and reacted with sodium sulfite at a mass ratio of 1:0.5 at 120°C for 2 h to obtain the loofah extract.

[0042] Oxidized konjac glucomannan was dissolved in deionized water to obtain a 5% oxidized konjac glucomannan solution. Silk fibroin was added to the oxidized konjac glucomannan solution at a mass ratio of 1:0.5, the pH was adjusted to 9.0, and the mixture was stirred at 50°C for 1 hour. Tannic acid was then added and stirred to mix evenly. Oxidized konjac glucomannan and tannic acid were mixed at a mass ratio of 1:0.2, and 0.5 mol / L ferric chloride solution was added dropwise. The molar ratio of tannic acid to ferric chloride was 3:1. The mixture was stirred at room temperature for 30 minutes to obtain a dynamic network base solution.

[0043] The dynamic network base liquid was mixed with the loofah extract, and the mixture was homogenized at 8000 rpm at 60°C for 15 min. Xanthan gum, nanocellulose and methylcellulose were added in sequence and stirred at 45°C until there were no particles. Glycerin, aloe vera gel, sorbitol and rosemary extract were added, and the pH was adjusted to 7.0. The mixture was homogenized in a vacuum at -0.08 MPa for 30 min for degassing. The mixture was passed through a 200-mesh sieve and then filled and sealed to obtain an environmentally friendly glue for children's picture books based on natural plant extracts.

[0044] Example 4: Environmentally friendly glue for children's picture books based on natural plant extracts, and its preparation method and application, comprising the following steps:

[0045] Prepare the following components: 13 parts by weight of loofah extract, 55 parts by weight of dynamic network base liquid, 1.5 parts by weight of xanthan gum, 2.3 parts by weight of nanocellulose, 0.6 parts by weight of methylcellulose, 4 parts by weight of aloe vera gel, 2 parts by weight of glycerin, 4 parts by weight of sorbitol, and 0.7 parts by weight of rosemary extract;

[0046] The dynamic network base liquid is obtained by mixing oxidized konjac glucomannan, silk fibroin, tannic acid and ferric chloride;

[0047] The dried loofah was mechanically crushed to a particle size of 0.5 mm, and defatted with 70% ethanol at 60°C for 2 h to obtain defatted loofah. The defatted loofah was mixed with 2 mol / L NaOH solution at a mass ratio of 1:15, refluxed at 90°C for 3 h, and centrifuged. The supernatant was refluxed with acetic acid and hydrochloric acid at a volume ratio of 9:1 at 70°C for 2 h. The precipitate was washed with water until neutral, freeze-dried, and reacted with sodium sulfite at a mass ratio of 1:0.5 at 120°C for 2 h to obtain the loofah extract.

[0048] Oxidized konjac glucomannan was dissolved in deionized water to obtain a 5% oxidized konjac glucomannan solution. Silk fibroin was added to the oxidized konjac glucomannan solution at a mass ratio of 1:0.5, the pH was adjusted to 9.0, and the mixture was stirred at 50°C for 1 hour. Tannic acid was then added and stirred to mix evenly. Oxidized konjac glucomannan and tannic acid were mixed at a mass ratio of 1:0.2, and 0.5 mol / L ferric chloride solution was added dropwise. The molar ratio of tannic acid to ferric chloride was 3:1. The mixture was stirred at room temperature for 30 minutes to obtain a dynamic network base solution.

[0049] The dynamic network base liquid was mixed with the loofah extract, and the mixture was homogenized at 8000 rpm at 60°C for 15 min. Xanthan gum, nanocellulose and methylcellulose were added in sequence and stirred at 45°C until there were no particles. Glycerin, aloe vera gel, sorbitol and rosemary extract were added, and the pH was adjusted to 7.0. The mixture was homogenized in a vacuum at -0.08 MPa for 30 min for degassing. The mixture was passed through a 200-mesh sieve and then filled and sealed to obtain an environmentally friendly glue for children's picture books based on natural plant extracts.

[0050] Example 5: Environmentally friendly glue for children's picture books based on natural plant extracts, and its preparation method and application, comprising the following steps:

[0051] Prepare the following components: 15 parts by weight of loofah extract, 55 parts by weight of dynamic network base liquid, 1.5 parts by weight of xanthan gum, 2.3 parts by weight of nanocellulose, 0.6 parts by weight of methylcellulose, 4 parts by weight of aloe vera gel, 2 parts by weight of glycerin, 4 parts by weight of sorbitol, and 0.7 parts by weight of rosemary extract;

[0052] The dynamic network base liquid is obtained by mixing oxidized konjac glucomannan, silk fibroin, tannic acid and ferric chloride;

[0053] The dried loofah was mechanically crushed to a particle size of 0.5 mm, and defatted with 70% ethanol at 60°C for 2 h to obtain defatted loofah. The defatted loofah was mixed with 2 mol / L NaOH solution at a mass ratio of 1:15, refluxed at 90°C for 3 h, and centrifuged. The supernatant was refluxed with acetic acid and hydrochloric acid at a volume ratio of 9:1 at 70°C for 2 h. The precipitate was washed with water until neutral, freeze-dried, and reacted with sodium sulfite at a mass ratio of 1:0.5 at 120°C for 2 h to obtain the loofah extract.

[0054] Oxidized konjac glucomannan was dissolved in deionized water to obtain a 5% oxidized konjac glucomannan solution. Silk fibroin was added to the oxidized konjac glucomannan solution at a mass ratio of 1:0.5, the pH was adjusted to 9.0, and the mixture was stirred at 50°C for 1 hour. Tannic acid was then added and stirred to mix evenly. Oxidized konjac glucomannan and tannic acid were mixed at a mass ratio of 1:0.2, and 0.5 mol / L ferric chloride solution was added dropwise. The molar ratio of tannic acid to ferric chloride was 3:1. The mixture was stirred at room temperature for 30 minutes to obtain a dynamic network base solution.

[0055] The dynamic network base liquid was mixed with the loofah extract, and the mixture was homogenized at 8000 rpm at 60°C for 15 min. Xanthan gum, nanocellulose and methylcellulose were added in sequence and stirred at 45°C until there were no particles. Glycerin, aloe vera gel, sorbitol and rosemary extract were added, and the pH was adjusted to 7.0. The mixture was homogenized in a vacuum at -0.08 MPa for 30 min for degassing. The mixture was passed through a 200-mesh sieve and then filled and sealed to obtain an environmentally friendly glue for children's picture books based on natural plant extracts.

[0056] Example 6: Environmentally friendly glue for children's picture books based on natural plant extracts, and its preparation method and application, comprising the following steps:

[0057] Prepare the following components: 15 parts by weight of loofah extract, 55 parts by weight of dynamic network base liquid, 0.5 parts by weight of xanthan gum, 1.2 parts by weight of nanocellulose, 0.3 parts by weight of methylcellulose, 2 parts by weight of aloe vera gel, 1 part by weight of glycerin, 2 parts by weight of sorbitol, and 0.3 parts by weight of rosemary extract;

[0058] The dynamic network base liquid is obtained by mixing oxidized konjac glucomannan, silk fibroin, tannic acid and ferric chloride;

[0059] The dried loofah was mechanically crushed to a particle size of 0.5 mm, and defatted with 70% ethanol at 60°C for 2 h to obtain defatted loofah. The defatted loofah was mixed with 2 mol / L NaOH solution at a mass ratio of 1:15, refluxed at 90°C for 3 h, and centrifuged. The supernatant was refluxed with acetic acid and hydrochloric acid at a volume ratio of 9:1 at 70°C for 2 h. The precipitate was washed with water until neutral, freeze-dried, and reacted with sodium sulfite at a mass ratio of 1:0.5 at 120°C for 2 h to obtain the loofah extract.

[0060] Oxidized konjac glucomannan was dissolved in deionized water to obtain a 5% oxidized konjac glucomannan solution. Silk fibroin was added to the oxidized konjac glucomannan solution at a mass ratio of 1:0.5, the pH was adjusted to 9.0, and the mixture was stirred at 50°C for 1 hour. Tannic acid was then added and stirred to mix evenly. Oxidized konjac glucomannan and tannic acid were mixed at a mass ratio of 1:0.2, and 0.5 mol / L ferric chloride solution was added dropwise. The molar ratio of tannic acid to ferric chloride was 3:1. The mixture was stirred at room temperature for 30 minutes to obtain a dynamic network base solution.

[0061] The dynamic network base liquid was mixed with the loofah extract, and the mixture was homogenized at 8000 rpm at 60°C for 15 min. Xanthan gum, nanocellulose and methylcellulose were added in sequence and stirred at 45°C until there were no particles. Glycerin, aloe vera gel, sorbitol and rosemary extract were added, and the pH was adjusted to 7.0. The mixture was homogenized in a vacuum at -0.08 MPa for 30 min for degassing. The mixture was passed through a 200-mesh sieve and then filled and sealed to obtain an environmentally friendly glue for children's picture books based on natural plant extracts.

[0062] Comparative Example 1: The method of Example 5 was adopted, and the dynamic network base liquid was replaced with starch.

[0063] Comparative Example 2: The method of Example 5 was adopted, and the oxidized konjac glucomannan and silk fibroin were directly used without modifying the oxidized konjac glucomannan and silk fibroin by tannic acid and ferric chloride.

[0064] The present invention uses a dynamic network base liquid to prepare an environmentally friendly glue for children's picture books based on natural plant extracts. The performance index test items and test standards of the glue are as follows:

[0065] 80g / m² coated paper was cut into 25mm×100mm test pieces, and glue was applied (coating amount 0.2g / cm²). The bonding area was 25mm×25mm, and the pressure was 0.5MPa for 30s to compact. After curing for 24 hours, the paper was peeled 180° at a speed of 100mm / min using a universal material testing machine. The average peel strength (N / 25cm) was recorded to evaluate the adhesion of the glue to the picture book paper. The scene of children repeatedly turning pages was simulated to test the fatigue resistance of the bonding point. A bonding test piece with a bonding area of ​​10mm×50mm was prepared. The test piece was fixed on a folding endurance tester with a bending angle of 180° and a frequency of 60 times / min. The peel strength after 100 opening and closing cycles was tested, and the number of bending times when the adhesive layer cracked was also tested.

[0066] The environmentally friendly glue for children's picture books based on natural plant extracts prepared in Examples 1-6 and Comparative Examples 1-2 was tested according to the above standards, and the obtained data are shown in Table 1:

[0067] Table 1 Performance data of Examples 1-6 and Comparative Examples 1-2

[0068] The above data fully demonstrates that Examples 1-6, compared with Comparative Examples 1-2, can fully show the effect of the dynamic network base liquid on the bonding strength and bending resistance of the environmentally friendly glue for children's picture books based on natural plant extracts.

[0069] Since the present invention uses a dynamic network base liquid to prepare the environmentally friendly glue for children's picture books based on natural plant extracts, the performance of the environmentally friendly glue for children's picture books based on natural plant extracts is effectively improved by the dynamic network base liquid, as follows:

[0070] It can be seen from Examples 1-3 that with the continuous increase in the content of the dynamic network base liquid and the proportion of its components, the bonding strength and bending resistance of the environmentally friendly glue for children's picture books based on natural plant extracts are significantly improved. The dynamic covalent bonds formed by the aldehyde group of oxidized konjac glucomannan and the amino group of silk fibroin increase with the increase in the proportion of the base liquid, thereby forming a denser covalent cross-linked network with higher interfacial adhesion ability. The proportion of dynamic non-covalent bonds formed by tannic acid-Fe³⁺ coordination bonds is simultaneously increased, providing an additional energy dissipation path and enhancing the shear resistance, thereby significantly improving the bending resistance.

[0071] It can be seen from Examples 3-5 that with the continuous increase in the content of loofah extract, the bonding strength and bending resistance of the environmentally friendly glue for children's picture books based on natural plant extracts continue to increase. Loofah extract is rich in lignin, and its rigid aromatic ring structure can enhance the initial bonding strength of the glue layer and provide additional support for the glue. Since the phenolic hydroxyl and sulfonic acid groups in lignin can also form coordination bonds with Fe³⁺, the stability of the dynamic network is further enhanced. Loofah extract, as a natural filler, fills the pores in the dynamic network base liquid, reduces internal defects in the glue layer, improves the overall mechanical properties, and delays the cracking of the glue layer. At the same time, the polar groups in the loofah extract can form hydrogen bonds or van der Waals forces with the cellulose on the surface of the paper, thereby enhancing the adhesion of the glue to the paper. Therefore, the loofah extract optimizes the glue performance through the dual mechanisms of chemical coordination enhancement and physical toughening.

[0072] It can be seen from Examples 5 and 6 that with the continuous changes in the content of other components, the bonding strength and bending resistance of the environmentally friendly glue for children's picture books based on natural plant extracts do not change significantly, indicating that small changes in other components within a certain range are not enough to significantly affect the bonding strength and bending resistance of the environmentally friendly glue for children's picture books based on natural plant extracts.

[0073] According to the above test experiments, the environmentally friendly glue for children's picture books based on natural plant extracts prepared according to Example 5 has the best performance, so Example 5 is taken as the best example;

[0074] By comparing Example 5 with Comparative Examples 1-2, it can be seen that:

[0075] In comparative example 1, the dynamic network base liquid is replaced with starch. The bonding strength and bending resistance of the environmentally friendly glue for children's picture books based on natural plant extracts are worse. Since the starch molecules are cross-linked through hydrogen bonds and van der Waals forces to form a rigid network, it lacks the reversibility of dynamic bonds and is prone to brittle fracture when stress is concentrated. It cannot release energy through bond reorganization when bending, and the cracks expand rapidly, resulting in debonding, making it unable to adapt to repeated stress.

[0076] In Comparative Example 2, oxidized konjac glucomannan and silk fibroin were directly used without modification by tannic acid and ferric chloride. The bonding strength and bending resistance of the environmentally friendly glue for children's picture books based on natural plant extracts were worse. When the dynamic network relied solely on the action of dynamic covalent bonds, its cross-linking density was significantly lower, resulting in an unstable network structure. The lack of tannic acid-Fe³⁺ coordination bonds caused the network to lack fast-response dynamic bonds, resulting in poor bonding strength and bending resistance.

[0077] In summary, through the dynamic network base liquid and loofah extract, the aldehyde group of oxidized konjac glucomannan in the dynamic network base liquid forms a reversible covalent bond with the amino group of silk fibroin, giving the glue self-healing ability. At the same time, the ortho-phenolic hydroxyl group of tannic acid coordinates and complexes with Fe³⁺ in ferric chloride to form a stable three-dimensional network, which significantly enhances the cohesion and fatigue resistance of the glue layer. The loofah extract is rich in lignin, and its phenolic hydroxyl group further coordinates with Fe³⁺, strengthening the stability of the dynamic network and reinforcing the glue layer through a rigid structure to improve the initial bonding strength. The synergistic effect of the two enables the glue to disperse stress through bond reorganization during repeated bending and maintain high peel strength.

[0078] The basic principles, main features, and advantages of the present invention are shown and described above. It should be understood by those skilled in the art that the present invention is not limited to the above-described embodiments. The above-described embodiments and descriptions are merely preferred examples of the present invention and are not intended to limit the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and modifications fall within the scope of the invention claimed.

Claims

1. Environmentally friendly glue for children's picture books based on natural plant extracts, characterized by: The invention comprises the following components: 10-15 parts by weight of loofah extract, 45-55 parts by weight of dynamic network base liquid, 0.5-1.5 parts by weight of xanthan gum, 1.2-2.3 parts by weight of nanocellulose, 0.3-0.6 parts by weight of methylcellulose, 2-4 parts by weight of aloe vera gel, 1-2 parts by weight of glycerin, 2-4 parts by weight of sorbitol and 0.3-0.7 parts by weight of rosemary extract; The dynamic network base liquid is obtained by mixing oxidized konjac glucomannan, silk fibroin, tannic acid and ferric chloride; The preparation method of dynamic network base liquid is as follows: Dissolving oxidized konjac glucomannan in deionized water to obtain an oxidized konjac glucomannan solution, adding silk fibroin to the oxidized konjac glucomannan solution, adjusting the pH to 8.5-9.0, stirring at 40-50° C. for 1-2 hours, then adding tannic acid and stirring to mix evenly, adding 0.5-1 mol / L ferric chloride solution dropwise, and stirring at room temperature for 20-30 minutes to obtain a dynamic network base liquid; The specific preparation steps of the loofah extract are: The dried loofah was mechanically crushed to a particle size of 0.5-1 mm, and defatted with 70-75% ethanol at 60-65°C for 2-3 h to obtain defatted loofah. The defatted loofah was mixed with 2-3 mol / L NaOH solution at a mass ratio of 1:13-15, refluxed at 85-90°C for 3-4 h, and centrifuged. The supernatant was refluxed with acetic acid and hydrochloric acid at a volume ratio of 9:1 at 70-75°C for 2-3 h. The precipitate was washed with water until neutral, freeze-dried, and reacted with sodium sulfite at 120-125°C for 2-3 h to obtain the loofah extract.

2. The environmentally friendly glue for children's picture books based on natural plant extracts according to claim 1, characterized in that: The mass ratio of the precipitate to sodium sulfite is 1:0.3-0.

5.

3. The environmentally friendly glue for children's picture books based on natural plant extracts according to claim 1, characterized in that: The mass fraction of the oxidized konjac glucomannan solution is 5-8%.

4. The environmentally friendly glue for children's picture books based on natural plant extracts according to claim 1, characterized in that: The mass ratio of the oxidized konjac glucomannan to the silk fibroin is 1:0.3-0.

5.

5. The environmentally friendly glue for children's picture books based on natural plant extracts according to claim 1, characterized in that: The mass ratio of the oxidized konjac glucomannan to tannic acid is 1:0.1-0.

2.

6. The environmentally friendly glue for children's picture books based on natural plant extracts according to claim 1, characterized in that: The molar ratio of the tannic acid to the ferric chloride is 2 to 4:

1.

7. A method for preparing an environmentally friendly glue for children's picture books based on natural plant extracts, which is used to prepare the environmentally friendly glue for children's picture books based on natural plant extracts according to any one of claims 1 to 6, characterized in that: The steps include: The dynamic network base liquid is mixed with the loofah extract, and the mixture is homogenized at a high speed of 8000-9000 rpm at 60°C for 15-20 minutes. Xanthan gum, nanocellulose and methylcellulose are added in sequence and stirred at 40-45°C until there are no particles. Glycerin, aloe vera gel, sorbitol and rosemary extract are added, and the pH is adjusted to 6.5-7.

5. The mixture is vacuum homogenized at -0.08 MPa for 25-30 minutes for degassing. The mixture is sieved through a 200-mesh sieve and then filled and sealed to obtain an environmentally friendly glue for children's picture books based on natural plant extracts.

8. Application of the environmentally friendly glue for children's picture books based on natural plant extracts obtained by the preparation method according to claim 7, characterized in that: This environmentally friendly glue for children's picture books based on natural plant extracts is used for bonding picture books to paper materials.

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