A bio-based fire-retardant hydrogel material and a method for preparing the same

Abstract

The application 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 hydroxypropyl cellulose, 11-11.5 parts of silica sol, 82.5-83.5 parts of water, and 0.1-0.3 parts of genipin.The bio-based fireproof hydrogel material and the preparation method thereof are used, the material prepared by the method realizes efficient fireproofing through a triple synergistic mechanism of heat absorption and temperature reduction, gas phase inhibition and condensed phase barrier, can provide a fireproofing time of more than 5 minutes for the protected object under a flame of 600-800 DEG C, and is significantly better than traditional hydrogels.In addition, the material prepared by the method is non-toxic and low in cost, and is suitable for fields such as building and forest fire prevention.

Description

TECHNICAL FIELD

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

[0002] Fire safety is becoming more and more important in modern life, and widely used high polymer materials have become one of the main materials causing fire due to their flammability, so the research on the flame-retardant modification of high polymer materials plays an important role and significance in public fire protection, safety production, and social stability development. Traditional fireproof hydrogels are mostly based on polyacrylic acid polymers, which rely on high water absorption to store water and reduce temperature, but have problems such as short fireproof time (<90 seconds) and easy decomposition failure at high temperature. In addition, the raw materials are not degradable and may cause microplastic pollution. In the prior art, although silicon-based materials can form a heat insulation layer by dehydration, it is difficult to balance flexibility and adhesion when used alone; and although chitosan derivatives have smoke suppression effect, they have insufficient thermal stability.

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

[0004] The present application aims to provide a bio-based fireproof hydrogel material and a preparation method thereof. The material prepared by the method realizes efficient fireproofing through a triple synergistic mechanism of "heat absorption and temperature reduction-gas phase inhibition-coagulation phase barrier", and can provide a fireproofing time of more than 5 minutes for the protected object under a flame of 600-800℃, which is significantly better than traditional hydrogels. In addition, the material prepared by the method is non-toxic and low in cost, and is suitable for use in the fields of building and forest fire prevention.

[0005] To achieve the above-mentioned purpose, the present application provides a bio-based fireproof hydrogel material, which 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.

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

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

[0008] Preferably, 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.

[0009] Preferably, the purity of the genipin is ≥98%, the molecular weight is 247.23 g / mol, and the use concentration is 0.5-1.5 wt% aqueous solution.

[0010] The application also provides a preparation method of the bio-based fireproof hydrogel material, which 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 a synergistic effect of physical cross-linking and chemical cross-linking, wherein the physical cross-linking is achieved by hydrogen bonds and van der Waals forces, and the chemical cross-linking is achieved by forming covalent bonds through the reaction of genipin and the amino group of carboxymethyl chitosan.

[0012] Preferably, the method comprises the following steps:

[0013] Step S1: The hydroxypropyl cellulose and the carboxymethyl chitosan are weighed according to the above-mentioned proportions, and then added into 63-63.5 parts of water at a temperature of 18-25℃ and stirred until completely dissolved to obtain a uniform solution A;

[0014] Step S2: The silica sol is mixed with the remaining 19.5-20 parts of water at 25℃ and stirred to obtain a dispersion B;

[0015] Step S3: The dispersion B is added into the solution A, and then magnetically stirred at a speed of 500 r / min for more than 8 hours at a temperature of 25℃, and the genipin is added to make the components fully cross-linked, thereby obtaining the bio-based fireproof hydrogel material.

[0016] The bio-based fireproof hydrogel material and the preparation method thereof have the following beneficial effects:

[0017] (1) The bio-based fireproof hydrogel material prepared in the application has a triple fireproof mechanism: heat absorption and temperature reduction: the hydroxypropyl cellulose (HPC) pores expand at high temperature to release water, and the silica sol dehydrates and absorbs heat at 180-250℃; gas phase inhibition: the carboxymethyl chitosan (CMCS) pyrolysis produces NH3 and CO2, which dilutes oxygen and captures free radicals; condensed phase barrier: the silica sol and the residual carbon layer form an expanded heat insulation layer to block heat radiation and oxygen; therefore, the bio-based fireproof hydrogel material can form a stable heat insulation layer under a flame of 600-800℃, and can protect the covered area from carbonization for more than 5 minutes.

[0018] (2) The bio-based fireproof hydrogel material prepared in the application can be sprayed on the surface of flammable materials such as wood and cables, or used for preparing fireproof coatings, forest fire retardants, etc., and is suitable for building fire retardation, forest fire prevention and industrial equipment protection, thus having a broad market prospect.

[0019] The technical solutions of the application will be further described in detail below with reference to the drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 Schematic diagram of fireproof mechanism of the bio-based fireproof hydrogel material prepared by the bio-based fireproof hydrogel material and the preparation method thereof;

[0021] Figure 2 Alcohol lamp burning experiment diagram of the bio-based fireproof hydrogel material prepared by example one of the bio-based fireproof hydrogel material and the preparation method thereof;

[0022] Figure 3 The wood board surface condition diagram of the hollow wood board in example one of the bio-based fireproof hydrogel material and the preparation method thereof when burning every 30s outside the alcohol lamp flame; wherein a is 0s, b is 30s, c is 60s, d is 90s, e is 120s, f is 150s, and g is 180s, the wood board side deformation condition;

[0023] Figure 4 Comparison diagram of heat insulation effect of the material prepared by comparative example one of the bio-based fireproof hydrogel material and the preparation method thereof under the flame;

[0024] Figure 5 Alcohol lamp burning experiment diagram of the bio-based fireproof hydrogel material prepared by comparative example two of the bio-based fireproof hydrogel material and the preparation method thereof. DETAILED DESCRIPTION

[0025] The technical solutions of the present application are further described below by means of the accompanying drawings and examples.

[0026] Unless otherwise defined, the technical terms or scientific terms used in the present application shall have the usual meanings understood by those skilled in the art to which the present application belongs.

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

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

[0029] The components have a synergistic effect: for example Figure 1As shown, carboxymethyl chitosan (CMCS) provides amino pyrolysis to generate NH3, inhibiting free radical chain reaction. Hydroxypropyl cellulose (HPC) constructs a temperature-sensitive network, releasing stored water at high temperature. Silica sol (CSP) dehydrates to form a SiO2 aerogel thermal insulation layer.

[0030] The bio-based fireproof hydrogel material is prepared from carboxymethyl chitosan, hydroxypropyl cellulose, silica sol, genipin, and water through physical and chemical cross-linking. The cross-linking method is a synergistic effect of physical cross-linking and chemical cross-linking, wherein the physical cross-linking is realized through hydrogen bonds and Van der Waals forces, and the chemical cross-linking is realized through the reaction of genipin and the amino group of carboxymethyl chitosan to form a covalent bond.

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

[0032] Step S1: Hydroxypropyl cellulose and carboxymethyl chitosan are weighed according to the above proportions, and 63-63.5 parts of water is added at a temperature of 18-25℃ and stirred until completely dissolved to obtain a uniform solution A.

[0033] Step S2: Silica sol is mixed with the remaining 19.5-20 parts of water at 25℃ and stirred to obtain a dispersion B.

[0034] Step S3: The dispersion B is added to the solution A, and the components are fully cross-linked by adding genipin under magnetic stirring at a speed of 500 r / min for more than 8 hours at a temperature of 25℃, to obtain a bio-based fireproof hydrogel material.

[0035] Example One

[0036] A bio-based fireproof hydrogel material and a preparation method thereof, comprising the following steps:

[0037] Step S1: 2.2g of hydroxypropyl cellulose and 3.3g of carboxymethyl chitosan are weighed and added to 63.2ml of water and stirred until completely dissolved to obtain a uniform solution A.

[0038] Step S2: 11.1g of silica sol is mixed with 20ml of water at 25℃, and dispersed by ultrasonic dispersion (power is 150W bath type ultrasonic instrument, dispersion temperature is 30℃, and dispersion time is 5 minutes) to obtain a dispersion B.

[0039] Step S3: The dispersion B is added to the solution A, and the components are fully cross-linked by adding 0.2g of natural chemical cross-linking agent genipin under magnetic stirring at a speed of 500 r / min for 9 hours at a temperature of 25℃, and then solidified by standing, to obtain a bio-based fireproof hydrogel material.

[0040] (I) The bio-based fireproof hydrogel material prepared in Example One is coated on a pine board (1mm thick), and placed in the flame of an alcohol lamp (700℃). As shown in Figure 2As shown, the wood board protected by the bio-based fireproof hydrogel material prepared in Example Three started to carbonize at 7 minutes and 13 seconds.

[0041] As shown in Fig. 1(a), the outer surface of the wood board at 0s. Figure 3 As shown in Fig. 1(b), the surface of the wood board was carbonized and blackened rapidly, and obvious flames were visible at about 70s. Figure 3 As shown in Fig. 1(c), the side of the wood board was deformed at 180s. Figure 3 As shown in Fig. 1(d), the wood board was completely ignited after 180s, with fierce flames, severe deformation and damage. Figure 3 As shown in Fig. 1(e), the wood board was completely carbonized after 240s. Figure 3 As shown in Fig. 1(f), the wood board was completely carbonized after 300s.

[0042] (II) The bio-based fireproof hydrogel material prepared in Example One was used to protect the surface of a 30x30mm wood board. 2 The results showed that the hydrogel prepared in Example One started to produce a large number of bubbles at about 60s of high temperature burning, which had the effect of blocking the flame. Within 120s, the hydrogel mainly achieved the effect of reducing temperature and blocking flame by evaporating its internal water, and gradually formed a SiO2 aerogel film at high temperature. The bubbles produced in this process and the tension of the hydrogel caused the remaining hydrogel to accumulate and cover a certain area. In the remaining time, the protective layer formed by the carbonization of the hydrogel products in this area still had a significant fireproof effect.

[0043] Example Two

[0044] A bio-based fireproof hydrogel material and a method for preparing the same, comprising the following steps:

[0045] A bio-based fireproof hydrogel material and a method for preparing the same, comprising the following steps:

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

[0047] Step S2, weigh 11.3g of silica sol and 20ml of water at 25°C, and mix by ultrasonic dispersion (power of 150W bath type ultrasonic instrument, dispersion temperature of 30°C, dispersion time of 5 minutes) to obtain dispersion liquid B.

[0048] Step S3, add dispersion liquid B to solution A and stir at a speed of 500r / min at a temperature of 25°C for 9 hours to allow the components to crosslink fully, and then allow to solidify to obtain the bio-based fireproof hydrogel material.

[0049] The bio-based fireproof hydrogel material prepared in Example Two was tested for fireproof performance.

[0050] (1) The fire retardant time effectiveness and environmental protection performance of the bio-based fire-resistant hydrogel material prepared in Comparative Example 1 were tested against the traditional polyacrylic acid hydrogel. The results are shown in Table 1.

[0051] Table 1 Test results

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

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

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

[0055] Comparative Example 2

[0056] A bio-based fireproof hydrogel material and a preparation method thereof, comprising the following steps:

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

[0058] Step S2: 12 g of silica sol was weighed and mixed with 20 mL of water at 25° C., and dispersed by ultrasound (power of 150 W bath type ultrasound instrument, dispersion temperature of 30° C., dispersion time of 5 minutes) to obtain dispersion B.

[0059] Step S3: adding dispersion B to solution A, magnetically stirring at a rate of 500 r / min at a temperature of 25° C. for 9 hours, adding 0.2 g of genipin to fully cross-link the components, and standing to solidify to obtain a bio-based fire-retardant 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 burner flame (700°C). Figure 5 As shown, it was measured that the wood board protected by the bio-based fire-resistant hydrogel material prepared in Comparative Example 2 was carbonized at 2 minutes and 52 seconds, and was also not as effective as the bio-based fire-resistant hydrogel material prepared in Example 1.

[0061] Therefore, the present invention adopts the above-mentioned bio-based fire-proof hydrogel material and its preparation method. The material prepared by this method achieves efficient fire protection through the triple synergistic mechanism of "heat absorption and cooling - gas phase inhibition - condensed phase barrier", and can provide the protected object with a fire protection time of more than 5 minutes 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 use in construction, forest fire prevention and other fields.

[0062] It should be pointed out finally that the above embodiments are only used to illustrate the technical solutions of the present application but not to limit it, and although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can still be modified or replaced equivalently, and these modifications or equivalent replacements should not make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present application.

Claims

1. A bio-based fireproof hydrogel material, characterized in that: The composition 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; The deacetylation degree of the carboxymethyl chitosan is ≥85%, and the substitution degree of the carboxymethyl chitosan is 0.6-0.8; The degree of substitution of the hydroxypropyl cellulose is 1.8-2.5, and the molecular weight is 80,000-120,000.

2. 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 silicon dioxide particles with a particle size of 10-50nm.

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

4. A method for preparing the bio-based fire-resistant hydrogel material according to any one of claims 1 to 3, characterized in that: The bio-based fireproof hydrogel material is prepared from carboxymethyl chitosan, hydroxypropyl cellulose, silica sol, genipin and water through physical and chemical cross-linking.

5. The method for preparing a bio-based fireproof hydrogel material according to claim 4, characterized in that: The cross-linking method is a synergistic effect of physical cross-linking and chemical cross-linking, wherein the physical cross-linking is achieved through hydrogen bonding and van der Waals forces, and the chemical cross-linking is achieved by the reaction of genipin with the amino groups of carboxymethyl chitosan to form covalent bonds.

6. The method for preparing a bio-based fireproof hydrogel material according to claim 5, characterized in that: The following steps are involved: Step S1, weighing hydroxypropyl cellulose and carboxymethyl chitosan according to the above ratio, adding 63-63.5 parts of water at a temperature of 18-25° C. and stirring until completely dissolved to obtain a homogeneous solution A; Step S2, mixing the silica sol with the remaining 19.5-20 parts of water at 25° C. to obtain dispersion B; Step S3: adding dispersion B to solution A, magnetically stirring at a rate of 500 r / min at a temperature of 25° C. for more than 8 hours, adding genipin to fully cross-link the components, thereby obtaining a bio-based fire-retardant hydrogel material.

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