Efficient heat-insulation flame-retardant wall cloth and preparation method thereof

Abstract

The invention provides efficient heat-insulation flame-retardant wall cloth and a preparation method thereof.The preparation method comprises the following steps that S1, a substrate is placed in an ethanol solution containing gamma-aminopropyltriethoxysilane to be subjected to ultrasonic treatment and dried, and a pretreated substrate is obtained; s2, waterborne polyurethane, melamine modified phenolic resin, expansible graphite, silicon dioxide aerogel powder and microencapsulated ammonium polyphosphate are mixed according to the mass percent, formed slurry is sprayed to the surface of the pretreated substrate, curing is conducted, and a flame-retardant coating is formed; s3, spinning a spinning solution containing polyimide, silicon dioxide aerogel powder and an organic solvent to obtain a nanofiber membrane; s4, a nanofiber membrane is compounded to the surface of the flame-retardant coating in a hot-pressing mode, and a nanometer heat insulation layer is formed; s5, finally, the substrate is placed in the self-repairing liquid to be repeatedly soaked and dried, and the efficient heat-insulation flame-retardant wall cloth is obtained. The limit oxygen index of the prepared wall cloth is larger than or equal to 35%, UL94 is V-0 level, the heat conductivity coefficient is smaller than or equal to 0.03 W / m.K, and the excellent heat insulation and flame retardant effects are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of furniture wall coverings, and particularly to a highly efficient heat-insulating and flame-retardant wall covering and a preparation method thereof. Background Art

[0002] With the acceleration of the urbanization process and the improvement of building safety standards, the application demand for flame-retardant materials in the fields of architecture, transportation, aerospace, etc. is increasing day by day. As an interior decoration material for buildings, the main functions of traditional wall coverings are concentrated on aesthetics and basic protection, but their heat-insulating and flame-retardant properties in fires often fail to meet the stringent safety requirements of modern high-rise buildings, underground spaces, and transportation vehicles. In recent years, the frequent major fires across the country have further exposed the limitations of traditional flame-retardant materials, and there is an urgent need for a new type of wall covering with high efficiency in heat insulation, active flame retardancy, and light weight.

[0003] Currently, most existing traditional wall coverings adopt a single-function design. They mainly achieve flame retardancy by adding flame retardants. However, if the addition amount is too high, it will lead to deterioration of mechanical properties, or use glass wool, rock wool, or porous foam layers for flame retardancy and heat insulation. Although it can delay heat transfer, the material has a large thickness, is flammable, and is difficult to integrate with decorative wall coverings, restricting its application in lightweight scenarios. Summary of the Invention

[0004] (1) Technical Problems to be Solved

[0005] In view of the deficiencies of the prior art, the present invention provides a highly efficient heat-insulating and flame-retardant wall covering and a preparation method thereof, solving the problems raised in the above background art.

[0006] (2) Technical Solutions

[0007] To achieve the above objectives, the present invention is realized through the following technical solutions:

[0008] According to the first aspect of the present invention, a preparation method of a highly efficient heat-insulating and flame-retardant wall covering is provided, including the following steps:

[0009] S1. Place the substrate in an ethanol solution containing γ-aminopropyltriethoxysilane for ultrasonic treatment, and then dry it to obtain a pretreated substrate;

[0010] S2. By mass percentage, mix waterborne polyurethane, melamine-modified phenolic resin, expandable graphite, silica aerogel powder, and microencapsulated ammonium polyphosphate, and spray the formed slurry on the surface of the pretreated substrate, then cure it to form a flame-retardant coating on the surface of the pretreated substrate;

[0011] S3. Spin a spinning solution containing polyimide, silica aerogel powder, and an organic solvent to obtain a nanofiber membrane;

[0012] S4. Thermally press and laminate the nanofiber membrane onto the surface of the flame retardant coating to form a nano thermal insulation layer;

[0013] S5. Immerse the substrate obtained in step S4 repeatedly in the self-healing liquid and then dry it to obtain the highly efficient thermal insulation and flame retardant wall fabric.

[0014] Preferably, in step S1, the concentration of γ-aminopropyltriethoxysilane in the ethanol solution containing γ-aminopropyltriethoxysilane is 5-7 wt%;

[0015] The substrate is selected from glass fiber or cotton fabric;

[0016] The time of the ultrasonic treatment is 20-50 min, and the drying temperature is 80-100 °C.

[0017] Preferably, in step S2, in the slurry, by mass fraction, it includes 40-60% of waterborne polyurethane, 20-40% of melamine-modified phenolic resin, 10-25% of expandable graphite, 5-15% of silica aerogel powder, and 1-4% of microencapsulated ammonium polyphosphate.

[0018] Preferably, the preparation method of the microencapsulated ammonium polyphosphate is as follows:

[0019] Add chitosan to the aqueous solution containing ammonium polyphosphate, adjust the pH to acidic, then add sodium tripolyphosphate for ionic crosslinking, and perform centrifugal separation and drying to obtain microencapsulated ammonium polyphosphate.

[0020] Preferably, the mass ratio of ammonium polyphosphate, sodium tripolyphosphate to chitosan is 3-5:1-2:1.

[0021] Preferably, in step S2, the curing temperature is 100-130 °C and the time is 20-40 min.

[0022] Preferably, in step S3, in the spinning solution, the mass concentration of polyimide is 10-15 wt%, and the mass concentration of silica aerogel powder is 5-8 wt%;

[0023] The organic solvent in the spinning solution is selected from dimethylacetamide and / or acetone;

[0024] The voltage for spinning is 20-25 kV, the receiving distance is 10-15 cm, the flow rate is 1-3 mL / h, and the environmental humidity ≤ 30%.

[0025] Preferably, in step S4, the temperature for thermal pressing is 180-200 °C, the pressure is 5-7 MPa, and the time is 5-10 s.

[0026] Preferably, in step S5, the self-healing liquid, by mass fraction, comprises 40-65% of waterborne polyurethane, 20-45% of microencapsulated ammonium polyphosphate, and 10-15% of nano clay.

[0027] According to a second aspect of the present invention, there is provided a highly heat-insulating and flame-retardant wall cloth obtained by the above preparation method.

[0028] (III) Beneficial effects

[0029] The present invention provides a highly heat-insulating and flame-retardant wall cloth and a preparation method thereof. The following beneficial effects are achieved:

[0030] (1) In the preparation method of a highly heat-insulating and flame-retardant wall cloth provided by this solution, melamine-modified phenolic resin and microencapsulated ammonium polyphosphate are used in synergy to avoid the release of toxic gases of traditional halogen-based flame retardants. The expandable graphite expands rapidly when encountering fire, forming a dense carbon layer to isolate oxygen. At the same time, microencapsulated ammonium polyphosphate is released at high temperature or mechanical damage, reacting with melamine-modified phenolic resin to generate a phosphoric acid carbon layer, achieving double flame retardancy. In addition, the silica aerogel powder blocks heat conduction and convection through its nano-porous structure in the flame-retardant coating and nanofiber membrane, and the overall thermal conductivity can be controlled below 0.03 W / m·K, having excellent flame retardancy and heat insulation performance.

[0031] (2) In the preparation method of a highly heat-insulating and flame-retardant wall cloth provided by this solution, the substrate is pretreated with γ-aminopropyltriethoxysilane to enhance the adhesion between the coating and the substrate through chemical bonding, improving the glass strength, and avoiding the problem of easy separation of the coating in the traditional process. Finally, by coating the self-healing liquid, a microcapsule gradient distribution can be formed on the surface. When there are slight scratches or local high temperature, the microcapsules rupture to release ammonium polyphosphate, and the repair efficiency can reach more than 80%, extending the service life of the wall cloth.

[0032] (3) For the highly heat-insulating and flame-retardant wall cloth provided by this solution, the limiting oxygen index can reach more than 35%, there is no penetration after being burned at 600 °C for 30 minutes, the thermal conductivity is less than 0.03 W / m·K, and the scratch repair rate is greater than 80%, having excellent heat insulation and flame retardancy effects. Specific embodiments

[0033] In order to better illustrate and elaborate the content of the present invention, specific embodiments are described below.

[0034] Example 1

[0035] Preparation of microencapsulated ammonium polyphosphate: 5 kg of ammonium polyphosphate was dispersed in deionized water, 1 kg of chitosan was added, the pH was adjusted to 4.5, and 1 kg of sodium tripolyphosphate was added to form chitosan-coated ammonium polyphosphate microcapsules, which were centrifuged and dried to obtain microencapsulated ammonium polyphosphate with a particle size of 5 to 10 μm;

[0036] Substrate pretreatment: The glass fiber substrate was placed in a 6 wt % γ-aminopropyltriethoxysilane ethanol solution for ultrasonic treatment for 30 min, and then dried at 80° C. to obtain a pretreated substrate;

[0037] Preparation of flame retardant coating: 50% waterborne polyurethane, 30% melamine-modified phenolic resin, 10% expandable graphite, 7% silica aerogel powder and 3% microencapsulated ammonium polyphosphate were mixed uniformly according to mass fraction, and the formed slurry was sprayed on the surface of the pretreated substrate and cured at 120°C for 25 minutes to form a flame retardant coating with a thickness of 0.2 mm on the surface of the pretreated substrate;

[0038] Preparation of nanofiber membrane: polyimide and silica aerogel powder were added to acetone solution to prepare spinning solution with a polyimide concentration of 14wt% and a silica aerogel powder concentration of 6wt%, and the spinning was carried out under the conditions of adjusting the spinning voltage to 20kV, the receiving distance to 12cm, the flow rate to 2mL / h, and the ambient humidity to less than 30%, to obtain a nanofiber membrane;

[0039] Preparation of nano thermal insulation layer: hot pressing the prepared nanofiber membrane at a temperature of 180° C. and a pressure of 6 MPa for 5 seconds, and compounding the nanofiber membrane to the surface of the flame retardant coating to form a nano thermal insulation layer;

[0040] Self-repairing treatment: The substrate after the above steps is repeatedly immersed in a self-repairing liquid containing 65wt% waterborne polyurethane, 25wt% microencapsulated ammonium polyphosphate and 10wt% nanoclay, and dried for 3 times to obtain a highly efficient heat-insulating flame-retardant wall cloth.

[0041] Example 2

[0042] Preparation of microencapsulated ammonium polyphosphate: 3 kg of ammonium polyphosphate was dispersed in deionized water, 1 kg of chitosan was added, the pH was adjusted to 4.5, and 2 kg of sodium tripolyphosphate was added to form chitosan-coated ammonium polyphosphate microcapsules, which were centrifuged and dried to obtain microencapsulated ammonium polyphosphate with a particle size of 5 to 10 μm;

[0043] Substrate pretreatment: The cotton fabric substrate was placed in a 7 wt % γ-aminopropyltriethoxysilane ethanol solution for ultrasonic treatment for 30 min, and then dried at 80° C. to obtain a pretreated substrate;

[0044] Preparation of flame retardant coating: By mass fraction, 45% of waterborne polyurethane, 27% of melamine-modified phenolic resin, 15% of expandable graphite, 9% of silica aerogel powder, and 4% of microencapsulated ammonium polyphosphate were mixed evenly. The formed slurry was sprayed on the surface of the pretreated substrate and cured at 120 °C for 25 min to form a flame retardant coating with a thickness of 0.2 mm on the surface of the pretreated substrate;

[0045] Preparation of nanofiber membrane: Polyimide and silica aerogel powder were added to an acetone solution to prepare a spinning solution with a polyimide concentration of 14 wt% and a silica aerogel powder concentration of 8 wt%. Electrospinning was carried out under the conditions of a regulated spinning voltage of 20 kV, a receiving distance of 12 cm, a flow rate of 2 mL / h, and an environmental humidity of less than 30% to obtain a nanofiber membrane;

[0046] Preparation of nano-insulation layer: The prepared nanofiber membrane was hot-pressed at a temperature of 180 °C and a pressure of 6 MPa for 5 s, and the nanofiber membrane was laminated onto the surface of the flame retardant coating to form a nano-insulation layer;

[0047] Self-healing treatment: The substrate obtained through the above steps was repeatedly immersed in a self-healing solution containing 65 wt% waterborne polyurethane, 25 wt% microencapsulated ammonium polyphosphate, and 10 wt% nano-clay, and then dried three times to obtain a highly efficient heat-insulating and flame-retardant wall cloth.

[0048] Flame retardancy test:

[0049] The highly efficient heat-insulating and flame-retardant wall cloths of Example 1 and Example 2 were respectively cut into wall cloth samples of 10 cm × 10 cm; according to the standard of ASTM D2863, the samples were placed in an oxygen index meter, the oxygen / nitrogen ratio was adjusted, and the lowest oxygen concentration for maintaining combustion was measured; according to the UL94 standard, the samples were vertically fixed, a flame was applied for 10 s, and the burning time, dripping substances, and self-extinguishing properties were recorded; the samples were calcined in a muffle furnace at 600 °C for 30 min, and the carbon layer thickness and expansion rate were measured; the samples were ignited in a smoke density chamber, and the light flux attenuation rate was measured. The test results are shown in Table 1.

[0050] Table 1

[0051]

[0052]

[0053] From the data in Table 1, it can be seen that the limiting oxygen index of the highly efficient heat-insulating and flame-retardant wall cloth prepared by the present invention can reach more than 35%, which is a flame-retardant material, UL94 is V-0 grade, and there is no penetration after burning at 600 °C for 30 min.

[0054] Heat insulation test:

[0055] The thermal conductivity of the sample was measured at 25 °C using a laser thermal conductivity meter; under a nitrogen atmosphere with a heating rate of 10 °C / min, the weight loss rate and the endothermic / exothermic peaks were recorded; finally, the sample was placed under an 800 °C heat source, and a thermocouple was attached to the back surface to record the temperature rise state on the back surface within 30 min. The test results are shown in Table 2.

[0056] Table 2

[0057]

[0058] According to the data in Table 2, it can be seen that the silica aerogel powder and the nanofiber membrane are distributed in layers, and the heat conduction and convection are blocked through the nanoporous structure, resulting in a significant increase in the heat insulation effect.

[0059] Mechanical properties and durability tests:

[0060] The coating and the substrate were peeled off at a speed of 50 mm / min using a universal testing machine, and the maximum load was recorded; after abrasion with a 1 kg load for 1000 revolutions, the mass loss rate was measured; a notch with a depth of 50 μm was scratched on the surface of the sample, and after heating at 50 °C for 10 min, the scratch width repair rate was measured. The specific data are shown in Table 3:

[0061] Table 3

[0062] Test indicators Peeling strength (N / cm) Wear mass loss rate (%) Scratch repair rate (%) Example 1 8.6 2.1 86％ Example 2 8.4 2.0 88％

[0063] According to the data in Table 3, it can be seen that the prepared high-efficiency heat-insulating and flame-retardant wall cloth has a self-repairing function, high peel strength, and the coating is not easy to separate, greatly improving the service life of the wall cloth.

[0064] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A preparation method of an efficient heat-insulating and flame-retardant wall cloth, characterized in that: It includes the following steps: S1. Place the substrate in an ethanol solution containing γ-aminopropyltriethoxysilane for ultrasonic treatment, and then dry it to obtain a pretreated substrate; S2. Mix aqueous polyurethane, melamine-modified phenolic resin, expandable graphite, silica aerogel powder and microencapsulated ammonium polyphosphate by mass percentage, and spray the formed slurry on the surface of the pretreated substrate, then cure it to form a flame-retardant coating on the surface of the pretreated substrate; S3. Spin a spinning solution containing polyimide, silica aerogel powder and an organic solvent to obtain a nanofiber membrane; S4. Thermally press and laminate the nanofiber membrane onto the surface of the flame-retardant coating to form a nano thermal insulation layer; S5. Immerse the substrate obtained in step S4 repeatedly in a self-healing liquid, and then dry it to obtain the high-efficiency thermal insulation and flame-retardant wall fabric.

2. The preparation method of an efficient heat-insulating and flame-retardant wall cloth according to claim 1, characterized in that: In step S1, the concentration of γ-aminopropyltriethoxysilane in the ethanol solution containing γ-aminopropyltriethoxysilane is 5-7 wt%; The substrate is selected from glass fiber or cotton fabric; The time of the ultrasonic treatment is 20-50 min, and the drying temperature is 80-100 °C.

3. The preparation method of an efficient heat-insulating and flame-retardant wall cloth according to claim 1, wherein: In step S2, in the slurry, by mass fraction, it includes 40-60% of aqueous polyurethane, 20-40% of melamine-modified phenolic resin, 10-25% of expandable graphite, 5-15% of silica aerogel powder and 1-4% of microencapsulated ammonium polyphosphate.

4. The preparation method of an efficient heat-insulating and flame-retardant wall cloth according to claim 1, characterized in that: The preparation method of the microencapsulated ammonium polyphosphate is as follows: Add chitosan to an aqueous solution containing ammonium polyphosphate, adjust the pH to acidic, then add sodium tripolyphosphate for ionic crosslinking, centrifuge and separate, and dry to obtain microencapsulated ammonium polyphosphate.

5. The preparation method of an efficient heat-insulating and flame-retardant wall cloth according to claim 4, characterized in that: The mass ratio of ammonium polyphosphate, sodium tripolyphosphate to chitosan is 3-5:1-2:

1.

6. The preparation method of an efficient heat-insulating and flame-retardant wall cloth according to claim 1, characterized in that: In step S2, the curing temperature is 100-130 °C and the time is 20-40 min.

7. The preparation method of an efficient heat-insulating and flame-retardant wall cloth according to claim 1, characterized in that: In step S3, in the spinning solution, the mass concentration of polyimide is 10-15 wt%, and the mass concentration of silica aerogel powder is 5-8 wt%; The organic solvent in the spinning solution is selected from dimethylacetamide and / or acetone; The spinning voltage is 20-25 kV, the receiving distance is 10-15 cm, the flow rate is 1-3 mL / h, and the environmental humidity ≤ 30%.

8. The preparation method of an efficient heat-insulating and flame-retardant wall cloth according to claim 1, characterized in that: In step S4, the thermal pressing temperature is 180-200 °C, the pressure is 5-7 MPa, and the time is 5-10 s.

9. The preparation method of an efficient heat-insulating and flame-retardant wall cloth according to claim 1, characterized in that: In step S5, the self-healing liquid, by mass fraction, includes 40-65% of aqueous polyurethane, 20-45% of microencapsulated ammonium polyphosphate and 10-15% of nano clay.

10. A high-efficiency thermal insulation and flame-retardant wall fabric obtained by the preparation method according to any one of claims 1 to 9.

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