Bio-based fireproof hydrogel material and preparation method thereof

Abstract

The invention belongs to the technical field of high polymer materials, and particularly discloses a bio-based fireproof hydrogel material and a preparation method thereof, the bio-based fireproof hydrogel material comprises the following components by weight: 3-3.5 parts of carboxymethyl chitosan, 2-2.5 parts of hydroxy propyl cellulose, 11-11.5 parts of silica sol, 82.5-83.5 parts of water, and 0.1-0.3 part of genipin. According to the bio-based fireproof hydrogel material and the preparation method thereof disclosed by the invention, the material prepared by the method realizes efficient fire prevention through a triple synergistic mechanism of heat absorption and cooling, gas phase inhibition and condensed phase barrier, and can provide a protected object with a fireproof aging of more than 5 minutes under flame of 600-800 DEG C, which is obviously superior to that of the traditional hydrogel; in addition, the material prepared by the method is non-toxic, low in cost and suitable for the fields of buildings, forest fire prevention and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer materials, and particularly relates to a bio-based fireproof hydrogel material and a preparation method thereof. Background Art

[0002] Fire safety is becoming increasingly important in modern life. The widely used polymer materials have become one of the main materials causing fires due to their flammability. Therefore, the research on flame retardant modification of polymer materials plays an important role and significance in aspects such as public fire protection, safe production, and ensuring the stable development of society. Traditional fireproof hydrogels mostly use polyacrylic acid polymers as substrates, relying on high water absorption to store water and cool down, but there are problems such as short fireproof time (<90 seconds) and easy decomposition and failure at high temperatures. In addition, their raw materials are non-degradable and may cause microplastic pollution. And in the prior art, although silicon-based materials can form a heat insulation layer by dehydrating, it is difficult to balance flexibility and adhesion when used alone; while chitosan derivatives have a smoke suppression effect, but their thermal stability is insufficient.

[0003] Therefore, there is a need in this field to develop a bio-based fireproof hydrogel material and a preparation method thereof, which can effectively solve the above problems. Summary of the Invention

[0004] The purpose of the present invention is to provide a bio-based fireproof hydrogel material and a preparation method thereof. The material prepared by this method realizes efficient fire protection through a triple synergistic mechanism of "endothermic cooling - gas-phase inhibition - condensed-phase barrier", and can provide a fireproof time of more than 5 minutes for the protected object under a flame of 600 - 800 °C, which is significantly better than traditional hydrogels. In addition, the material prepared by this method is non-toxic and low-cost, and is suitable for fields such as building and forest fire prevention.

[0005] To achieve the above purpose, the present invention provides a bio-based fireproof hydrogel material, which includes the following components by weight: 3 - 3.5 parts of carboxymethyl chitosan, 2 - 2.5 parts of hydroxypropyl cellulose, 11 - 11.5 parts of silica sol, 82.5 - 83.5 parts of water, and 0.1 - 0.3 parts of genipin.

[0006] Preferably, the degree of deacetylation of the carboxymethyl chitosan ≥ 85%, and the substitution degree of the carboxymethyl chitosan is 0.6 - 0.8.

[0007] Preferably, the substitution degree of the hydroxypropyl cellulose is 1.8 - 2.5, and the molecular weight is 80,000 - 120,000.

[0008] Preferably, the mass fraction of SiO2 in the silica sol is 50 wt%; the silica sol is colloidal silica particles with a particle size of 10 - 50 nm.

[0009] Preferably, the purity of genipin is ≥98%, the molecular weight is 247.23 g / mol, and it is added in the form of an aqueous solution with a concentration of 0.5-1.5 wt%.

[0010] The present invention also provides a preparation method of a bio-based fireproof hydrogel material, and the bio-based fireproof hydrogel material is prepared by physical and chemical cross-linking of carboxymethyl chitosan, hydroxypropyl cellulose, silica sol, genipin, and water.

[0011] Preferably, the cross-linking method is the synergistic action of physical cross-linking and chemical cross-linking. Among them, physical cross-linking is achieved through hydrogen bonds and van der Waals forces, and chemical cross-linking forms covalent bonds through the reaction of genipin with the amino group of carboxymethyl chitosan.

[0012] Preferably, it includes the following steps:

[0013] Step S1: Weigh hydroxypropyl cellulose and carboxymethyl chitosan according to the above ratio, add them to 63-63.5 parts of water at a temperature of 18-25 °C, and stir until completely dissolved to obtain a homogeneous solution A;

[0014] Step S2: Mix and stir silica sol with the remaining 19.5-20 parts of water at 25 °C to obtain a dispersion B;

[0015] Step S3: Add dispersion B to solution A, magnetically stir at a rate of 500 r / min at 25 °C for more than 8 hours, add genipin, and fully cross-link the components to obtain the bio-based fireproof hydrogel material.

[0016] The present invention adopts the above-mentioned bio-based fireproof hydrogel material and its preparation method, and the beneficial effects are as follows:

[0017] (1) The bio-based fireproof hydrogel material prepared in the present invention has a triple fireproof mechanism: endothermic cooling: the pores of hydroxypropyl cellulose (HPC) expand at high temperature to release water, and silica sol dehydrates and absorbs heat at 180-250 °C; gas-phase inhibition: carboxymethyl chitosan (CMCS) pyrolyzes to produce NH3 and CO2, diluting oxygen and capturing free radicals; condensed-phase barrier: silica sol and the carbon residue layer form an expanded heat-insulating layer, blocking heat radiation and oxygen; Therefore, the bio-based fireproof hydrogel material can form a stable heat-insulating layer under a flame of 600-800 °C, protecting the covered area from carbonization for more than 5 minutes.

[0018] (2) The bio-based fireproof hydrogel material prepared in the present invention can be sprayed on the surfaces of flammable materials such as wood and cables, or used to prepare fireproof coatings, forest fire retardants, etc., and is suitable for building fire retardation, forest fire prevention, and industrial equipment protection. Therefore, it has broad market prospects.

[0019] The technical solutions of the present invention will be further described in detail below through the accompanying drawings and embodiments. Brief Description of the Drawings

[0020] Figure 1 Schematic diagram of the fire prevention mechanism of the bio-based fireproof hydrogel material prepared by the bio-based fireproof hydrogel material and its preparation method of the present invention;

[0021] Figure 2 Experimental diagram of burning the bio-based fireproof hydrogel material prepared in Example 1 of the bio-based fireproof hydrogel material and its preparation method of the present invention with an alcohol lamp;

[0022] Figure 3 Diagram of the surface condition of the hollow wooden board in Example 1 of the bio-based fireproof hydrogel material and its preparation method of the present invention when burned by the outer flame of an alcohol lamp every 30 s; where a is 0 s, b is 30 s, c is 60 s, d is 90 s, e is 120 s, f is 150 s, and g is the deformation condition of the side of the wooden board at 180 s;

[0023] Figure 4 Comparison diagram of the heat insulation effect of the material prepared in Comparative Example 1 of the bio-based fireproof hydrogel material and its preparation method of the present invention under the flame;

[0024] Figure 5 Experimental diagram of burning the bio-based fireproof hydrogel material prepared in Comparative Example 2 of the bio-based fireproof hydrogel material and its preparation method of the present invention with an alcohol lamp. Detailed Description of the Invention

[0025] The technical solutions of the present invention will be further described below with reference to the drawings and examples.

[0026] Unless otherwise defined, the technical terms or scientific terms used in the present invention should have the ordinary meanings understood by those of ordinary skill in the field to which the present invention belongs.

[0027] A bio-based fireproof hydrogel material comprises the following components by weight: 3 - 3.5 parts of carboxymethyl chitosan, 2 - 2.5 parts of hydroxypropyl cellulose, 11 - 11.5 parts of silica sol, 82.5 - 83.5 parts of water, and 0.1 - 0.3 parts of genipin.

[0028] Among them, the deacetylation degree of carboxymethyl chitosan ≥ 85%, and the substitution degree of carboxymethyl chitosan is 0.6 - 0.8. The substitution degree of hydroxypropyl cellulose is 1.8 - 2.5, and the molecular weight is 80,000 - 120,000. The mass fraction of silica sol is 50 wt%. The silica sol is colloidal silica particles with a particle size of 10 - 50 nm. The purity of genipin ≥ 98%, the molecular weight is 247.23 g / mol, and it is added in the form of an aqueous solution with a concentration of 0.5 - 1.5 wt%.

[0029] There is a synergistic effect among the components: such as Figure 1As shown, carboxymethyl chitosan (CMCS) provides amino groups for pyrolysis to generate NH3, inhibiting the free radical chain reaction. Hydroxypropyl cellulose (HPC) constructs a thermosensitive network and releases stored water at high temperatures. Colloidal silica (CSP) dehydrates to form a SiO2 aerogel thermal insulation layer.

[0030] The bio-based fireproof hydrogel material is prepared by physically and chemically crosslinking carboxymethyl chitosan, hydroxypropyl cellulose, colloidal silica, genipin, and water. The crosslinking method is the synergistic effect of physical crosslinking and chemical crosslinking. Physical crosslinking is achieved through hydrogen bonds and van der Waals forces, and chemical crosslinking forms covalent bonds through the reaction of genipin with the amino groups of carboxymethyl chitosan.

[0031] A preparation method of a bio-based fireproof hydrogel material includes the following steps:

[0032] Step S1: Weigh hydroxypropyl cellulose and carboxymethyl chitosan according to the above ratio, add them to 63 - 63.5 parts of water at a temperature of 18 - 25 °C, and stir until completely dissolved to obtain a homogeneous solution A.

[0033] Step S2: At 25 °C, mix colloidal silica with the remaining 19.5 - 20 parts of water and stir to obtain a dispersion B.

[0034] Step S3: Add dispersion B to solution A, magnetically stir at a rate of 500 r / min at a temperature of 25 °C for more than 8 hours, add genipin, and fully crosslink the components to obtain the bio-based fireproof hydrogel material.

[0035] Example 1

[0036] A bio-based fireproof hydrogel material and its preparation method include the following steps:

[0037] Step S1: Weigh 2.2 g of hydroxypropyl cellulose and 3.3 g of carboxymethyl chitosan, add them to 63.2 ml of water, and stir until completely dissolved to obtain a homogeneous solution A.

[0038] Step S2: Weigh 11.1 g of colloidal silica and 20 mL of water, mix them at 25 °C, and disperse them by ultrasonic dispersion (using a 150 W bath-type ultrasonic instrument, the dispersion temperature is 30 °C, and the dispersion time is 5 minutes) to obtain a dispersion B.

[0039] Step S3: Add dispersion B to solution A, magnetically stir at a rate of 500 r / min at a temperature of 25 °C for 9 hours, add 0.2 g of the natural chemical crosslinking agent genipin, fully crosslink the components, and let it stand for curing to obtain the bio-based fireproof hydrogel material.

[0040] (1) Coat the bio-based fireproof hydrogel material prepared in Example 1 on a pine board (1 mm thick) and place it in an alcohol lamp flame (700 °C). As Figure 2As shown, it was measured that the wooden board protected by the bio-based fireproof hydrogel material prepared in Example 3 started to carbonize at 7 minutes and 13 seconds.

[0041] As Figure 3 shown, the surface condition of the empty wooden board not protected by the bio-based fireproof hydrogel material prepared in Example 1 was observed every 30 s during the burning with the outer flame of an alcohol lamp. As Figure 3 shown in a of Figure 3 it, the appearance of the wooden board at 0 s is shown. As Figure 3 shown in b - Figure 3 f of it, as the burning time increased, the surface of the wooden board quickly carbonized and turned black, and obvious flames could be seen around 70 s.

[0042] (2) The surface of a 30×30 mm 2 wooden board protected by the bio-based fireproof hydrogel material prepared in Example 1 was fire-retarded.

[0043] The results showed that for the hydrogel prepared in this Example 1, around 60 s of high-temperature burning, a large number of bubbles began to be generated, showing the effect of blocking the flame. Within 120 s, the hydrogel mainly reduced the temperature and blocked the flame by evaporating the internal moisture, and gradually formed a SiO2 aerogel film at high temperature. During this process, the bubbles generated and the tension of the hydrogel caused the remaining hydrogel to accumulate and cover an area. In the remaining time, the protective layer formed by the carbonization of the reaction product of the hydrogel in this area still had a significant fireproof effect.

[0044] Comparative Example 1

[0045] A bio-based fireproof hydrogel material and its preparation method include the following steps:

[0046] Step S1: Weigh 2.2 g of hydroxypropyl cellulose and 3.2 g of carboxymethyl chitosan, add them to 63 ml of water and stir until completely dissolved to obtain a homogeneous solution A.

[0047] Step S2: Weigh 11.3 g of silica sol and 20 mL of water, mix them at 25 °C, and disperse them by ultrasonic waves (using a 150 W bath-type ultrasonic instrument, with a dispersion temperature of 30 °C and a dispersion time of 5 minutes) to obtain a dispersion B.

[0048] Step S3: Add the dispersion B to the solution A, magnetically stir at a rate of 500 r / min at 25 °C for 9 hours to fully crosslink the components, and then let it stand for curing to obtain the bio-based fireproof hydrogel material.

[0049] The fireproof performance of the bio-based fireproof hydrogel material prepared in Comparative Example 1 was tested.

[0050] (1) The bio-based fireproof hydrogel material prepared in Comparative Example 1 was tested for fireproof aging and environmental friendliness with traditional polyacrylic acid hydrogel, and the results are shown in Table 1.

[0051] Table 1 Test Results

[0052] Parameter Hydrogel of Comparative Example 1 Traditional polyacrylic acid hydrogel Fire protection time limit 5 - 6 minutes < 90 seconds Environmental friendliness Non - toxic and biodegradable Microplastic pollution risk

[0053] (2) The bio-based fireproof hydrogel material prepared in Comparative Example 1 was coated on a pine board (1 mm thick) and placed in an alcohol lamp flame (700 °C).

[0054] As Figure 4 shown, the covered area did not carbonize within 5 minutes, and the fireproof aging reached 5 minutes and 30 seconds. Although it was significantly better than the traditional hydrogel (90 seconds), it was not as good as the effect of the bio-based fireproof hydrogel material prepared in Example 1.

[0055] Comparative Example 2

[0056] A bio-based fireproof hydrogel material and its preparation method, including the following steps:

[0057] Step S1: Weigh 2.4 g of hydroxypropyl cellulose and 3.6 g of carboxymethyl chitosan, add them to 62 ml of water and stir until completely dissolved to obtain a homogeneous solution A.

[0058] Step S2: Weigh 12 g of silica sol and 20 mL of water and mix them at 25 °C, and disperse them by ultrasonic dispersion (using a 150 W bath-type ultrasonic instrument, the dispersion temperature is 30 °C, and the dispersion time is 5 minutes) to obtain a dispersion liquid B.

[0059] Step S3: Add the dispersion liquid B to the solution A, magnetically stir at a rate of 500 r / min at a temperature of 25 °C for 9 hours, add 0.2 g of genipin to fully crosslink the components, and let it stand and solidify to obtain the bio-based fireproof hydrogel material.

[0060] The bio-based fireproof hydrogel material prepared in Comparative Example 2 was coated on a pine board (1 mm thick) and placed in an alcohol lamp flame (700 °C). As Figure 5 shown, it was measured that the wooden board protected by the bio-based fireproof hydrogel material prepared in Comparative Example 2 showed carbonization at 2 minutes and 52 seconds, and it was also not as good as the effect of the bio-based fireproof hydrogel material prepared in Example 1.

[0061] Therefore, the present invention adopts the above-mentioned bio-based fireproof hydrogel material and its preparation method. The material prepared by this method realizes efficient fire protection through the triple synergistic mechanism of "endothermic cooling - gas-phase inhibition - condensed-phase barrier", and can provide a fireproof aging of more than 5 minutes for the protected object under a 600 - 800 °C flame, which is significantly better than traditional hydrogels; in addition, the material prepared by this method is non-toxic and low-cost, and is suitable for fields such as construction and forest fire prevention.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions of the present invention or make equivalent replacements, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A bio-based fireproof hydrogel material, characterized in that, Comprising the following components by weight: 3 - 3.5 parts of carboxymethyl chitosan, 2 - 2.5 parts of hydroxypropyl cellulose, 11 - 11.5 parts of silica sol, 82.5 - 83.5 parts of water, and 0.1 - 0.3 parts of genipin.

2. The bio-based fireproof hydrogel material according to claim 1, characterized in that: The deacetylation degree of the carboxymethyl chitosan is ≥85%, and the substitution degree of the carboxymethyl chitosan is 0.6 - 0.

8.

3. The bio-based fireproof hydrogel material according to claim 1, characterized in that: The substitution degree of the hydroxypropyl cellulose is 1.8 - 2.5, and the molecular weight is 80,000 - 120,000.

4. The bio-based fireproof hydrogel material according to claim 1, characterized in that: The mass fraction of SiO2 in the silica sol is 50wt%; the silica sol is colloidal silica particles with a particle size of 10 - 50nm.

5. The bio-based fireproof hydrogel material according to claim 1, characterized in that: The purity of the genipin is ≥98%, the molecular weight is 247.23g / mol, and it is added in the form of an aqueous solution with a concentration of 0.5 - 1.5wt%.

6. A preparation method of the bio-based fireproof hydrogel material according to any one of claims 1-5, characterized in that: The bio - based fire - resistant hydrogel material is prepared by physical and chemical cross - linking of carboxymethyl chitosan, hydroxypropyl cellulose, silica sol, genipin, and water.

7. The preparation method of a bio-based fireproof hydrogel material according to claim 6, characterized in that: The cross - linking method is the synergistic effect of physical cross - linking and chemical cross - linking. Among them, physical cross - linking is achieved through hydrogen bonds and van der Waals forces, and chemical cross - linking forms covalent bonds through the reaction of genipin with the amino group of carboxymethyl chitosan.

8. The preparation method of a bio-based fireproof hydrogel material according to claim 7, characterized in that, Including the following steps: Step S1: Weigh hydroxypropyl cellulose and carboxymethyl chitosan according to the above ratio, add them to 63 - 63.5 parts of water at a temperature of 18 - 25°C and stir until completely dissolved to obtain a homogeneous solution A; Step S2: Mix and stir the silica sol with the remaining 19.5 - 20 parts of water at 25°C to obtain a dispersion B; Step S3: Add the dispersion B to the solution A, magnetically stir at a rate of 500r / min at 25°C for more than 8 hours, add genipin, and make the components fully cross - link to obtain the bio - based fire - resistant hydrogel material.

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