CN111875909B

CN111875909B - Composite flame-retardant heat-insulation cooling material and thixotropic hydrogel thereof

Info

Publication number: CN111875909B
Application number: CN202010649829.XA
Authority: CN
Inventors: 王戈; 陈明曦; 冯亚菲; 张寒露
Original assignee: Chinese People's Liberation Army 92228
Current assignee: Chinese People's Liberation Army 92228
Priority date: 2020-07-08
Filing date: 2020-07-08
Publication date: 2022-06-10
Anticipated expiration: 2040-07-08
Also published as: CN111875909A

Abstract

The invention discloses a composite flame-retardant heat-insulating cooling material and thixotropic hydrogel thereof, which are prepared by compounding super absorbent resin, water-soluble metal salt, water-soluble polysaccharide hydrosol, water-insoluble inorganic particles and a modifier through a compounding process, wherein the ratio of the super absorbent resin to the water is 1: mixing and stirring the components in a mass ratio of 80-250, and standing for 1-3 minutes to form the hydrogel. The hydrogel has excellent thermal protection performance, flexible texture, strong adhesiveness, no toxicity, no irritation, environmental protection, safety and reliability.

Description

Composite flame-retardant heat-insulation cooling material and thixotropic hydrogel thereof

Technical Field

The invention relates to a heat-insulating protective material, in particular to a composite flame-retardant heat-insulating temperature-reducing material and thixotropic hydrogel thereof, belonging to the technical field of heat-insulating materials.

Background

The fields of battle fields, fire fields, petrochemical industry, coal metallurgy and the like inevitably have potential heat hazard sources, and the expression forms of the heat hazard sources can be combustion, explosion, high-temperature gas, molten metal liquid drops, water vapor, high-temperature liquid splashes and the like. The super absorbent resin has strong water absorption and water retention, low price and environmental protection, a plurality of patents are available at present, the super absorbent resin is applied to a water-based fire extinguishing agent, the fire extinguishing effect is very obvious through a fire extinguishing mechanism of evaporating and cooling a large amount of water and isolating oxygen and combustible substances, and the on-site rapid cooling is realized after fire extinguishing.

Patent 201910550565.X proposes a preparation method and application of a fireproof and heat-insulating material with hydrogel as a substrate, wherein a double-network hydrogel is connected onto flame-retardant materials such as a basalt film, and the characteristics of high vaporization latent heat and high specific heat capacity of the hydrogel are respectively used as a fireproof layer, and the low heat conductivity of the basalt film is used as a heat-insulating layer, so that fireproof and heat insulation are realized simultaneously.

As the hydrogel is in an amorphous state, has low adhesion to a three-dimensional object and lacks of high-temperature structural stability, the reports and precedents that the hydrogel is independently applied to the flame-retardant heat insulation field are not available so far.

Disclosure of Invention

The invention aims to provide a composite flame-retardant heat-insulating and temperature-reducing material and thixotropic hydrogel thereof. The material has excellent flame retardant, heat insulation and cooling performances, and can comprehensively obstruct heat conduction, heat convection and heat radiation; meanwhile, the hydrogel composite system has thixotropy, so that the hydrogel composite system is very convenient to widely popularize and apply.

The technical solution for realizing the purpose of the invention is as follows: a composite flame-retardant heat-insulation cooling material is prepared by compounding super absorbent resin, water-soluble metal salt, water-soluble polysaccharide hydrosol, water-insoluble inorganic particles and a modifier to obtain composite flame-retardant heat-insulation powder, wherein the composite flame-retardant heat-insulation cooling material comprises the following components in percentage by mass:

preferably, the super absorbent resin can be polyacrylate, polyacrylamide, etc., and the particle size ranges from 3.5 to 40 microns.

Preferably, the metal salt can be one or more of sodium pyrophosphate, aluminum sulfate, sodium chloride, magnesium sulfate and the like, and the particle size ranges from 2.5 to 15 microns.

Preferably, the curdlan can be one or more of carrageenan, curdlan, xanthan gum and guar gum, and has particle size of 0.05-0.1 μm.

Preferably, the heat insulation particles can be one or a plurality of attapulgite, bentonite, diatomite, glass beads and the like, and the particle size ranges from 15 to 100 microns.

Preferably, the flame-retardant particles can be one or a plurality of melamine, melamine cyanurate, melamine phosphate and the like, and the particle size ranges from 15 to 100 micrometers.

Preferably, the nano-oxide can be one or a plurality of silicon dioxide, titanium dioxide, zirconium dioxide, aluminum dioxide and the like, and the particle size ranges from 0.05 to 0.1 micron.

Preferably, the modifier can be liquid surfactant such as sodium dodecyl benzene sulfonate, sodium dodecyl sulfate, etc., and can also be silane coupling agent such as DN630, DN631, HK550, HK560, HK570, etc.

The preparation method of the material comprises the following steps: mixing the raw materials according to the proportion, running for 2-5 minutes at 800 revolutions per minute in a high-speed compounding machine, then carrying out high-speed compounding for 15-20 minutes at 3800 revolutions per minute in 3000 revolutions per minute, controlling the temperature of dry powder to be 50-60 ℃, cooling to room temperature, discharging and packaging to obtain the powdery composite flame-retardant heat-insulating cooling material.

The invention also provides a thixotropic hydrogel based on the composite flame-retardant heat-insulating and temperature-reducing material, which is prepared by mixing the composite flame-retardant heat-insulating and temperature-reducing material with water (such as purified water, tap water, natural fresh water, desalinated seawater and the like) according to the weight ratio of 1: mixing and stirring the components in a mass ratio of 80-250, and standing for 1-3 minutes to form the hydrogel.

The thixotropic hydrogel is applied to the surfaces of inflammable articles such as textiles, wood, rubber and the like in a manual smearing or electric/pressure spraying mode, and the protective effects of instantaneous temperature reduction, high-efficiency heat insulation and long-acting flame retardance are exerted. Can also be directly applied to human body coats and exposed skin surfaces to serve as temporary heat protection clothes. According to actual needs, the coating can be supplemented, sprayed or smeared repeatedly at any time.

Compared with the prior art, the invention has the advantages that: the composite material is powder when being transported and stored, and has small volume, light weight and convenient storage. When in use, the water-soluble polyurethane emulsion is mixed with water, forms hydrogel after rapid water absorption, and has the advantages of excellent thermal protection performance, flexible texture, strong adhesiveness, no toxicity, no irritation, environmental protection, safety and reliability.

Drawings

FIG. 1 is a schematic diagram of a method for testing hydrogel adhesion.

Detailed Description

The technical solution of the present invention is described in detail below with reference to examples, but the scope of protection is not limited thereto.

The design idea of the thixotropic hydrogel based on the composite heat-insulating flame-retardant cooling material is as follows: (1) the unique three-dimensional space network structure of the super absorbent resin firmly restrains water, the formed hydrogel body still has good water retention performance under the high-temperature condition, and water molecules have quite large heat capacity and evaporation heat and show excellent cooling capacity. (2) The easily water-soluble metal salt is a flame retardant, so that the fire resistance of the hydrogel is remarkably improved, the forming speed of the hydrogel can be accelerated, and the phenomenon of white cores is avoided. (3) The polysaccharide substance dissolved in water can enhance the three-dimensional adhesion of the hydrogel to a three-dimensional surface, and has the characteristics of thermal expansion, thermal curing and the like, so that the high-temperature adhesion and stability of a gel system are further ensured. (4) The hydrogel is endowed with a more stable three-dimensional skeleton structure while the heat insulation, flame retardation and heat reflection effects of the hydrogel are respectively exerted by the water-insoluble heat insulation particles, flame retardation particles and nano particles, the hydrogel is enabled to have thixotropy through reasonable particle size design, and the application convenience of a hydrogel system is improved. (5) The modifier mainly plays a role in optimizing and perfecting a hydrogel system and application performance.

The action mechanism of the thixotropic hydrogel based on the composite heat-insulating flame-retardant cooling material is as follows: there are three ways of heat transfer: conduction, convection, and radiation. The hydrogel system of the present invention simultaneously blocks the propagation of heat from these three aspects. The hydrogel main body is a core-shell structure system containing solid and liquid phases, and insoluble particles are uniformly doped in the middle of the hydrogel main body, so that the heat conduction coefficient is obviously lower than that of pure water; the material inside the hydrogel has extremely low fluidity, and the convection propagation of heat is difficult to realize; the heat radiation formed by high temperature and flame can be effectively shielded by the uniform gel structure in the composite system and the insoluble solid particles included in the gel structure.

The cooling mechanism of the thixotropic hydrogel based on the composite heat-insulating flame-retardant cooling material is as follows: when heated, the hydrogel absorbs heat by itself and evaporates water on the surface to take away a large amount of heat, so that the surface temperature of the heated area is reduced, and the rapid cooling capacity is shown. The modifier is used for adjusting the state of the interface between the hydrogel and the air, reducing the attraction between surface water molecules, increasing potential energy, enabling the hydrogel system to be heated and easier to vaporize, and further accelerating the cooling speed.

The fire-proof mechanism of the thixotropic hydrogel based on the composite heat-insulating flame-retardant cooling material is as follows: the high latent heat of vaporization and high specific heat capacity of the hydrogel are the basis of the fireproof application of the hydrogel, and the heat insulation, flame retardation and heat reflection effects of the hydrogel are further enhanced by scientific design and reasonable collocation of the heat insulation particles, the flame retardation particles, the nano particles and the like, so that the hydrogel has a stable three-dimensional framework structure at high temperature.

Through the cooperation of the above functions, the thixotropic hydrogel based on the composite heat-insulating flame-retardant cooling material provided by the invention has an excellent composite flame-retardant heat-insulating cooling function.

The formula of the composite heat-insulating flame-retardant cooling material comprises the following components in percentage by mass:

60-85% of super absorbent resin, preferably 65-85%, which can be polyacrylate, polyacrylamide and the like, and has a particle size of 3.5-40 microns;

② metal salt, 3-8%, preferably 3-6%, can be one or more of sodium pyrophosphate, aluminum sulfate, sodium chloride, magnesium sulfate, etc. compound, the particle size range is 2.5-15 micrometers;

③ 2 to 12 percent of coagulated polysaccharide, preferably 3 to 10 percent of coagulated polysaccharide, which can be one or a plurality of carrageenin, curdlan, xanthan gum, guar gum and the like, and the particle size ranges from 0.05 to 0.1 micron;

2-10%, preferably 2-8%, of heat insulation particles, wherein the heat insulation particles can be one or a plurality of attapulgite, bentonite, diatomite, glass beads and the like, and the particle size range is 15-100 micrometers;

flame-retardant particles, 2-10%, which can be one or a plurality of melamine, melamine cyanurate, melamine phosphate and the like, and the particle size range is 15-100 microns;

1.5-8%, preferably 1.5-5%, more preferably 1.5-2.5%, and can be one or more of silicon dioxide, titanium dioxide, zirconium dioxide, aluminum dioxide, etc. with particle size of 0.05-0.1 μm;

and 0.5-2% of modifier, which can be liquid surfactant such as sodium dodecyl benzene sulfonate, sodium dodecyl sulfate and the like, or silane coupling agent such as DN630, DN631, HK550, HK560, HK570 and the like.

Example 1

The composite heat-insulating flame-retardant cooling material is prepared by mixing all the raw materials according to the formula in table 1, running the mixture for 5 minutes at 500 revolutions per minute in a high-speed compound machine, then compounding the mixture for 20 minutes at 3500 revolutions per minute, controlling the temperature of dry powder to be 50-60 ℃ during the compounding, shutting down the machine, cooling the machine to room temperature, discharging and packaging the product.

Example 2

The composite heat-insulating flame-retardant cooling material is prepared by mixing all the raw materials according to the formula in table 1, running for 2 minutes at 800 revolutions per minute in a high-speed compound machine, then compounding for 15 minutes at 3000 revolutions per minute at a high speed, controlling the temperature of dry powder to be 50-60 ℃, shutting down, cooling to room temperature, discharging and packaging.

Example 3

The composite heat-insulating flame-retardant cooling material is prepared by mixing all the raw materials according to the formula in table 1 in a corresponding ratio, running for 5 minutes at 600 revolutions per minute in a high-speed compound machine, then compounding for 18 minutes at 3000 revolutions per minute at a high speed, controlling the temperature of dry powder to be 50-60 ℃ during the compounding, shutting down, cooling to room temperature, discharging and packaging.

Example 4

The composite heat-insulating flame-retardant cooling material is prepared by mixing all the raw materials according to the formula in table 1, running the mixture for 5 minutes at 500 revolutions per minute in a high-speed compound machine, then compounding the mixture for 18 minutes at 3500 revolutions per minute, controlling the temperature of dry powder to be 50-60 ℃, shutting down, cooling to room temperature, discharging and packaging.

Example 5

The composite heat-insulating flame-retardant cooling material is prepared by mixing all the raw materials according to the formula in table 1, running for 5 minutes at 700 rpm in a high-speed compound machine, then compounding for 20 minutes at 3500 rpm, controlling the temperature of dry powder to be 50-60 ℃, shutting down, cooling to room temperature, discharging and packaging.

Comparative example 1

The composite flame-retardant heat-insulating material is prepared by mixing all the raw materials according to the formula in the table 1 according to the corresponding proportion, running for 5 minutes at 700 revolutions per minute in a high-speed compound machine, then compounding for 20 minutes at 3600 revolutions per minute at a high speed, controlling the temperature of dry powder to be 50-60 ℃, shutting down, cooling to room temperature, discharging and packaging.

Comparative example 2

Comparative example 3

Table 1 Main components and mass fractions of composite flame-retardant heat-insulation cooling material

Note: and/represents 0.

Test method

The composite flame-retardant and heat-insulating materials prepared in the above examples and comparative examples were mixed with tap water in a ratio of 1: 150, uniformly stirring, and standing for 1 minute to form hydrogel. Carrying out the following tests (namely thixotropy, adhesiveness and thermal protection performance) on 1-3 pieces of hydrogel; the following test (i.e., char yield) was conducted on the composite flame-retardant and heat-insulating material according to item 4.

1. Thixotropy

The thixotropy of the gel material means that when the material is vibrated or stirred, the viscosity is reduced and the fluidity is increased, and the material can gradually recover to the original shape after standing. On the contrary, after the material is placed for a period of time, the viscosity is increased, and phenomena such as thickening, solidification and the like are shown. If the thixotropy is too small, the strength of the formed hydrogel material is low, and the application range is not large; if the thixotropy is too high, spraying or painting is difficult, so that the application is inconvenient.

The thixotropy is characterized by the degree of thickening or thickening, i.e. the ratio of the time of flow-out of the gel material after standing in the viscometer for 30 minutes and after standing for 30 seconds, the average of the three tests being taken.

2. Adhesiveness

The hydrogel belongs to rheological materials, and the adhesiveness of the hydrogel cannot be characterized according to the standard of a curing adhesive. A simple test method as shown in fig. 1 was used: after spraying the hydrogel for 10s under fixed pressure and keeping for 1min, the adhesive property of the hydrogel is represented by the thickness of the gel attached to the vertical face of a common commercially available plywood, and the average value of three different position points is taken.

3. Thermal protective performance

The thermal protection performance Test (TPP) is generally used for detecting the thermal protection capability of materials such as fabrics and the like on the comprehensive action of thermal radiation and thermal convection, and can directly reflect the thermal protection performance of hydrogel.

The specific test method is to place the sample horizontally on a specific heat source, and the heat source adopts 2 different heat transfer forms, namely heat convection and heat radiation. A copper sheet heat flow meter placed on the other side of the sample measures the temperature on the back side of the sample. And (3) obtaining the time t2 required by the second-level burn by comparing with a Stoll standard curve, and multiplying the time t2 by the exposure heat flow q to obtain a TPP value, wherein the TPP value is calculated as: TPP is t2 × q. The larger the TPP value is, the better the thermal protection performance, namely the thermal insulation performance of the fabric material is; conversely, the poorer the insulation performance. The method relates the thermal protection property of the material with human body feeling, can objectively realize the actual application effect of thermal protection, and is listed as a universal test method. In the invention, the hydrogel with the thickness of 1mm is selected to carry out TPP test.

4. Rate of carbon residue

The carbon residue rate is the percentage of the mass of the residue of the organic material decomposed at high temperature to the mass of the original material, and can relatively represent the structural stability of the heat-insulating material at high temperature. For the composite material powder, the residual mass percentage at 600 ℃ in a thermogravimetric analysis (TG) test is selected as the carbon residue rate in the invention.

Test results

The results of comparing the properties of the examples with those of the comparative examples are shown in Table 2.

TABLE 2 comparison of composite flame-retardant and heat-insulating material powder and hydrogel properties thereof

Note: and/means not measured.

As can be seen from the data in Table 2, the hydrogels obtained in examples 1 to 5 of the present invention all have good thermal protection properties, appropriate thixotropy, strong adhesion, and good high temperature structural stability.

Comparative example 1 the formulation of metal salt and modifier was not added, resulting in poor hydrogel forming performance of the obtained composite flame-retardant and heat-insulating material, and a part of the powder remained not to be dissolved by water after 1min to 1hr, forming a white core. Therefore, only the carbon residue rate test of item 4 was conducted.

Comparative example 2 the absence of the polysaccharide component in the formulation resulted in a hydrogel with significantly lower adhesion than the examples and other comparative examples.

Compared with the prior art, insoluble particles such as heat insulation, flame retardance, nano oxides and the like are not added in the formula of the comparative example 3, so that the carbon residue rate of the obtained composite flame-retardant heat-insulating material is obviously low, and the thixotropy of the prepared hydrogel is also low.

Claims

1. The thixotropic hydrogel based on the composite flame-retardant heat-insulation cooling material is characterized in that the composite flame-retardant heat-insulation cooling material and water are mixed according to the weight ratio of 1: mixing and stirring the components in a mass ratio of 80 to 250, and standing for 1 to 3 minutes to obtain hydrogel;

the composite flame-retardant heat-insulation cooling material comprises the following components in percentage by mass:

60-85% of super absorbent resin

3 to 8 percent of metal salt

2-12% of coagulated polysaccharide

2 to 10 percent of heat insulation particles

2-10% of flame-retardant particles

1.5 to 8 percent of nano oxide

0.5-2% of a modifier;

the composite flame-retardant heat-insulation cooling material comprises the following preparation steps:

mixing the raw materials according to the proportion, running for 2-5 minutes at 800 revolutions per minute in a high-speed compounding machine, then changing to 3000 revolutions per minute at 3800 revolutions per minute for 15-20 minutes, and controlling the temperature of the dry powder to be 50-60 ℃ during the process.

2. A thixotropic hydrogel as claimed in claim 1 wherein the superabsorbent resin comprises any one or more of polyacrylate and polyacrylamide and has a particle size in the range of 3.5 to 40 microns.

3. The thixotropic hydrogel of claim 1 wherein the metal salt is selected from the group consisting of sodium pyrophosphate, aluminum sulfate, sodium chloride and magnesium sulfate and has a particle size in the range of 2.5 to 15 μm.

4. A thixotropic hydrogel according to claim 1 wherein the curdlan is one or more of carrageenan, curdlan, xanthan and guar gum and has a particle size in the range of from 0.05 to 0.1 microns.

5. A thixotropic hydrogel as claimed in claim 1 wherein the insulating particles are selected from one or more of attapulgite, bentonite, diatomaceous earth and glass beads and have a particle size in the range of 15 to 100 microns.

6. A thixotropic hydrogel as claimed in claim 1 wherein the flame retardant particles are selected from one or more of melamine, melamine cyanurate and melamine phosphate and have a particle size in the range of 15 to 100 microns.

7. The thixotropic hydrogel of claim 1, wherein the nano-oxide is selected from the group consisting of one or more of silicon dioxide, titanium dioxide, zirconium dioxide and aluminum dioxide, and has a particle size in the range of 0.05 to 0.1 μm.

8. The thixotropic hydrogel of claim 1, wherein the modifying agent is a liquid surfactant.

9. A thixotropic hydrogel as claimed in claim 8 wherein the liquid surfactant is sodium dodecylbenzene sulfonate or sodium lauryl sulfate.

10. The thixotropic hydrogel of claim 1, wherein the modifying agent is a silane coupling agent.

11. The thixotropic hydrogel of claim 1, wherein the silane coupling agent is selected from any one or more of DN630, DN631, HK550, HK560 and HK 570.

12. Use of a thixotropic hydrogel according to any one of claims 1 to 11 wherein the hydrogel is applied to a textile, wood or rubber surface.

13. Use of a thixotropic hydrogel according to any one of claims 1 to 11 wherein the hydrogel is applied to the outer clothing and exposed skin surfaces of the human body.

14. Use according to claim 12 or 13, wherein said use comprises manual painting, or electric/pressure spraying.