A fire-resistant and heat-insulating coating, its preparation method, and a high-pressure gas cylinder containing the same.

Abstract

This invention provides a fire-resistant and heat-insulating coating, comprising, by weight: 5-10 parts hollow glass microspheres, 40-60 parts modified polyamide resin, 1-5 parts film-forming aid, 15-30 parts titanate coupling agent, and 30-50 parts water; wherein the hollow glass microspheres are pre-treated with the titanate coupling agent; the modified polyamide resin is a hydroxyl-terminated polydimethylsiloxane-modified polyamide resin; the preparation method is as follows: after mixing the film-forming aid and water, the titanate coupling agent and binder are added and dispersed at high speed, then the surface-treated hollow glass microspheres are added and stirred evenly to obtain the coating; a fire-resistant and heat-insulating high-pressure gas cylinder includes an inner liner, and a winding layer, the above-mentioned fire-resistant and heat-insulating coating layer, and a fire-resistant layer arranged sequentially from the inside to the outside of the inner liner; the fire-resistant and heat-insulating coating of this invention can reduce the heat transfer efficiency of the gas cylinder, has better fire-resistant and heat-insulating effect, and can exhibit better mechanical properties.

Description

Technical Field

[0001] This invention relates to the field of high-pressure gas cylinder technology, and more specifically, to a fire-resistant and heat-insulating coating, a preparation method thereof, and a high-pressure gas cylinder containing the same. Background Technology

[0002] Existing Type III high-pressure gas cylinders are generally composite cylinders consisting of a metal inner liner (aluminum or steel), with fibers wound around the outer cylinder body and end caps. The winding layer is typically made of carbon fiber, while the protective layer is usually made of glass fiber. Carbon fiber typically has a heat resistance temperature below 300℃, while glass fiber typically has a heat resistance temperature of around 350℃. However, in the event of a fire, the cylinder temperature can rise rapidly to 800℃, which the fiber-wound inner liner alone cannot withstand. This would significantly reduce its performance, or even cause it to fail, greatly increasing the risk of explosion during valve release. Therefore, it is necessary to design and process the protective layer of the inner liner to meet the fire resistance requirements of the gas cylinder. Summary of the Invention

[0003] The purpose of this invention is to provide a fire-resistant and heat-insulating coating, a preparation method thereof, and a high-pressure gas cylinder containing the same, which can reduce the heat transfer efficiency of the gas cylinder, have better fire-resistant and heat-insulating effects, and exhibit better mechanical properties.

[0004] The embodiments of the present invention are achieved through the following technical solutions:

[0005] A fire-resistant and heat-insulating coating, by weight, comprises: 5-10 parts of hollow glass microspheres, 40-60 parts of modified polyamide resin, 1-5 parts of film-forming aid, 15-30 parts of titanate coupling agent, and 30-50 parts of water; wherein the hollow glass microspheres are pre-treated with the titanate coupling agent; and the modified polyamide resin is a hydroxyl-terminated polydimethylsiloxane-modified polyamide resin.

[0006] The surface treatment method of the hollow glass microspheres is as follows: the hollow glass microspheres are added to an ethanol solution and mixed evenly, and the reaction temperature is controlled at 50-70℃. Then, 0.2-0.8% of the mass of the hollow glass microspheres of coupling agent is added. After reacting for 1-2 hours, the mixture is cooled to room temperature, filtered, and dried at 100-150℃ for 1-3 hours to obtain the hollow glass microspheres.

[0007] The modified polyamide resin is prepared as follows: polyamide resin and hydroxyl-terminated polydimethylsiloxane are weighed and mixed evenly at a mass ratio of 3-5:1, and then heated to 60-90℃ for pre-reaction for 0.5-1h; then oxalic acid is added, and the temperature is further increased to 90-110℃ for reaction for 0.5-1h; finally, bismuth isooctanoate is added dropwise at a slow rate, and the temperature is further increased to 110-130℃ and vacuumed for 2h to obtain the hydroxyl-terminated polydimethylsiloxane-modified polyamide resin.

[0008] A method for preparing a fire-resistant and heat-insulating coating includes the following steps: mixing a film-forming aid and water, adding a titanate coupling agent and a binder, dispersing at high speed, then adding surface-treated hollow glass microspheres, and stirring evenly to obtain the fire-resistant and heat-insulating coating.

[0009] A fire-resistant and heat-insulating high-pressure gas cylinder includes an inner liner, and a winding layer, the aforementioned fire-resistant and heat-insulating coating layer, and a fire-resistant layer, which are sequentially disposed on the outer surface of the inner liner from the inside to the outside.

[0010] The technical solutions of the embodiments of the present invention have at least the following advantages and beneficial effects:

[0011] The fire-resistant and heat-insulating coating of this invention incorporates surface-treated hollow glass microspheres, which enhances the interfacial compatibility and adhesion between the microspheres and the polyamide resin. This results in more uniform dispersion of the microspheres within the coating, reducing microsphere agglomeration, increasing specific surface area, and consequently lowering heat transfer efficiency. Furthermore, the coating exhibits superior mechanical properties. Simultaneously, its combination with the polyamide resin modified with terminal hydroxyl polydimethylsiloxane improves overall bonding strength, facilitating the decomposition of the modified polyamide resin under thermo-oxidative conditions. This promotes the enrichment of silicon elements, forming a stable hybrid carbon layer containing silicon, oxygen, and carbon, hindering gas and heat exchange and delaying further matrix decomposition. Moreover, the Si-O bond has a higher bond energy than the CO and CC bonds, requiring greater energy to degrade the epoxy network structure, thus resulting in superior fire-resistant and heat-insulating effects. Detailed Implementation

[0012] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0013] The following is a detailed description of a fire-resistant and heat-insulating coating, its preparation method, and a high-pressure gas cylinder containing the coating, provided by embodiments of the present invention.

[0014] A fire-resistant and heat-insulating coating comprises insulating glass microspheres, a binder, a film-forming aid, and a titanate coupling agent; the binder is a modified polyamide resin; the insulating glass microspheres are pre-treated for surface treatment; the weight ratio of the insulating glass microspheres, binder, film-forming aid, titanate coupling agent, and water is 5-10:40-60:1-5:15-30:30-50 parts. In addition, flame retardants, pigments, etc., can be added to the coating according to application requirements.

[0015] Furthermore, the film-forming aid is one or more of BYK-190, propylene glycol methyl ether, dipropylene glycol methyl ether, defoamer, wetting agent, and thickener, and is not limited thereto. Those skilled in the art can add or subtract it as needed.

[0016] Further, the surface treatment method of the hollow glass microspheres is as follows: the hollow glass microspheres are added to an ethanol solution and mixed evenly, and the reaction temperature is controlled at 50-70℃. Then, 0.2-0.8% of the coupling agent by weight of the hollow glass microspheres is added. After reacting for 1-2 hours, the mixture is cooled to room temperature, filtered, and dried at 100-150℃ for 1-3 hours to obtain the hollow glass microspheres.

[0017] In ethanol solution, the hydroxyl groups on the surface of hollow glass microspheres react with the O-Ti-O groups of the titanate coupling agent, causing the coupling agent to be grafted onto the surface of the glass microspheres. This greatly improves the interfacial compatibility and adhesion between the hollow glass microspheres and polyamide resin, resulting in more uniform dispersion of the hollow glass microspheres in the coating. This reduces the agglomeration of the hollow glass microspheres in the coating, increases the specific surface area, and thus reduces the heat transfer efficiency. Furthermore, it allows the coating to exhibit better mechanical properties, especially a significant improvement in elongation at break.

[0018] Further, the adhesive is a polyamide resin modified with hydroxyl-terminated polydimethylsiloxane; the preparation method of the adhesive is as follows: weigh the polyamide resin and the hydroxyl-terminated polydimethylsiloxane at a mass ratio of 3-5:1, mix them evenly, and then heat to 60-90℃ for pre-reaction for 0.5-1h; then add oxalic acid, continue to heat to 90-110℃, and react for 0.5-1h; finally, slowly add bismuth isooctanoate dropwise, continue to heat to 110-130℃, and vacuum for 2h to obtain the hydroxyl-terminated polydimethylsiloxane modified polyamide resin.

[0019] Modified resins were prepared by copolymerizing polyamide resin matrices with hydroxyl-terminated polydimethylsiloxane. This introduced flexible and high-energy Si-O bonds, resulting in improved toughness and heat resistance. This is mainly due to the fact that the modified polyamide resin decomposes under thermo-oxidative conditions, which facilitates the enrichment of silicon elements to form a stable hybrid carbon layer containing silicon, oxygen, and carbon. This hinders the exchange of gas and heat, delaying further decomposition of the matrix. Moreover, the Si-O bonds have a higher bond energy than CO and CC bonds, requiring more energy to degrade the epoxy network structure, thus exhibiting better fire resistance and heat insulation effects.

[0020] A method for preparing a fire-resistant and heat-insulating coating includes the following steps: mixing a film-forming aid and water, adding a titanate coupling agent and a binder, dispersing at high speed, then adding surface-treated hollow glass microspheres, and stirring evenly to obtain the fire-resistant and heat-insulating coating.

[0021] Specifically: (1) Mix water and film-forming aids (such as dispersants, defoamers, and wetting agents) and stir at a stirring speed of 100-500 rpm to form a uniform mixture;

[0022] (2) Slowly add titanate coupling agent and binder and disperse at high speed with stirring at 1500-2500 rpm to form a uniform mixture;

[0023] (3) The surface-treated hollow glass microspheres are added to the mixture formed in step (2) at a stirring speed of 100-150 rpm and stirred evenly at a stirring speed of 150-200 rpm to obtain the fire-resistant and heat-insulating coating.

[0024] A fire-resistant and heat-insulating high-pressure gas cylinder includes an inner liner and, from the inside out, a winding layer, a fire-resistant and heat-insulating coating layer, and a fire-resistant layer, which are sequentially disposed on the outer surface of the inner liner. The winding layer is formed by uniformly winding carbon fiber around the outer surface of the inner liner. The fire-resistant and heat-insulating coating is formed by uniformly distributing the fire-resistant and heat-insulating coating outside the winding layer through methods such as spraying, pre-impregnation, or brushing. The fire-resistant layer is formed by winding high-silica glass fiber around the outer side of the fire-resistant and heat-insulating coating layer, and finally curing to form a fire-resistant and heat-insulating high-pressure gas cylinder.

[0025] This invention relates to a high-pressure gas cylinder with an added layer of hollow glass microspheres for fire resistance and insulation outside the carbon fiber winding layer. In the event of a fire, this significantly reduces the heat transfer efficiency within the cylinder, slowing the rate of temperature rise and allowing the valve more time to release the gas. This greatly reduces the risk of explosion due to carbon fiber winding layer failure. Furthermore, a high-silica glass fiber layer is wound around the fire resistance and insulation layer. The high-silica glass fiber's high heat resistance effectively protects the cylinder from direct contact with the flame, while also enhancing its fire resistance, thus preventing the risk of explosion due to fiber and resin failure.

[0026] Example 1

[0027] A fire-resistant and heat-insulating coating comprises: 18g of hollow glass microspheres, 125g of modified polyamide resin binder, 8g of BYK-190 dispersant, 50g of titanate coupling agent, and 100g of water;

[0028] The hollow glass microspheres are pre-treated with the following method: the hollow glass microspheres are added to an ethanol solution and mixed, and the reaction temperature is controlled at 60℃. Then, 0.9g of titanate coupling agent is added. After reacting for 1.5h, the mixture is cooled to room temperature, filtered, and dried in an oven at 120℃ for 2h to obtain the final product.

[0029] The modified polyamide resin adhesive is prepared as follows: 80g of polyamide resin and 20g of hydroxyl-terminated polydimethylsiloxane are weighed and mixed evenly, and then heated to 80℃ for pre-reaction for 0.5h; then 0.6g of oxalic acid is added, and the temperature is further increased to 95℃ for reaction for 0.5h; finally, 0.5g of bismuth isooctanoate is added dropwise at a slow rate, and the temperature is further increased to 120℃ and vacuumed for 2h to obtain the hydroxyl-terminated polydimethylsiloxane-modified polyamide resin.

[0030] The preparation method of the above-mentioned fire-resistant and heat-insulating coating includes the following steps: after mixing BYK-190 dispersant and water and stirring evenly at a stirring speed of 300 rpm, slowly add titanate coupling agent and modified polyamide resin binder, and disperse evenly at a high speed of 2000 rpm. Then add surface-treated hollow glass microspheres and stir evenly at a stirring speed of 150 rpm to obtain the fire-resistant and heat-insulating coating.

[0031] A fire-resistant and heat-insulating high-pressure gas cylinder includes an inner liner and, from the inside out, a winding layer, a fire-resistant and heat-insulating coating layer, and a fire-resistant layer, sequentially disposed on the outer surface of the inner liner. The winding layer is made of carbon fiber wound on the outer surface of the inner liner in a winding sequence of 892 / 152 / 892 / 202 / 892 / 452 / 892 / 232 / 892 / 162 / 893, wherein the circumferential fiber winding thickness is 6.5 mm, the helical fiber winding thickness is 3.4 mm, and the circumferential tension decreases from 30 N to 25 N. The spiral tension decreases from 27N to 23N to form a carbon fiber winding layer; the fire-resistant and heat-insulating coating is uniformly sprayed onto the carbon fiber winding layer to form the fire-resistant and heat-insulating layer; the fire-resistant layer is formed by winding high-silica glass fiber in a winding sequence of 152 / 892, wherein the spiral winding thickness is 0.6mm, the circumferential winding thickness is 0.5mm, and the winding tension is 20N / 18N, forming a glass fiber fire-resistant layer, which is finally cured to form a fire-resistant and heat-insulating high-pressure gas cylinder.

[0032] Example 2

[0033] The difference between this embodiment and Embodiment 1 is that: a fire-resistant and heat-insulating coating includes: 15g of hollow glass microspheres, 120g of modified polyamide resin binder, 10g of BYK-190 dispersant, 55g of titanate coupling agent, and 100g of water;

[0034] The surface treatment method for hollow glass microspheres is as follows: add hollow glass microspheres to an ethanol solution and mix well, control the reaction temperature at 50℃, then add 1g of titanate coupling agent, react for 1 hour, cool to room temperature, filter, and dry in an oven at 120℃ for 2 hours to obtain the product.

[0035] Example 3

[0036] The difference between this embodiment and Embodiment 1 is that: a fire-resistant and heat-insulating coating includes: 17g of hollow glass microspheres, 128g of modified polyamide resin binder, 12g of BYK-190 dispersant, 57g of titanate coupling agent, and 100g of water;

[0037] The modified polyamide resin adhesive is prepared as follows: 60g of polyamide resin and 15g of hydroxyl-terminated polydimethylsiloxane are weighed and mixed evenly, and then heated to 80℃ for pre-reaction for 0.5h; then 0.5g of oxalic acid is added, and the temperature is further increased to 95℃ for reaction for 0.5h; finally, 0.35g of bismuth isooctanoate is added dropwise at a slow rate, and the temperature is further increased to 120℃ and vacuumed for 2h to obtain the hydroxyl-terminated polydimethylsiloxane-modified polyamide resin.

[0038] Example 4

[0039] The difference between this embodiment and Embodiment 1 is that: a fire-resistant and heat-insulating coating includes: 20g of hollow glass microspheres, 90g of modified polyamide resin binder, 5g of BYK-190 dispersant, 40g of titanate coupling agent, and 100g of water.

[0040] Example 5

[0041] The difference between this embodiment and Embodiment 1 is that: a fire-resistant and heat-insulating coating includes: 20g of hollow glass microspheres, 130g of modified polyamide resin binder, 9g of BYK-190 dispersant, 50g of titanate coupling agent, and 100g of water.

[0042] Example 6

[0043] The difference between this embodiment and Embodiment 1 is that: a fire-resistant and heat-insulating coating includes: 15g of hollow glass microspheres, 138g of modified polyamide resin binder, 5g of BYK-190 dispersant, 50g of titanate coupling agent, and 100g of water.

[0044] Comparative Example 1

[0045] The difference between this embodiment and Embodiment 1 is that the binder of the fire-resistant and heat-insulating coating is unmodified polyamide resin.

[0046] Comparative Example 2

[0047] The difference between this embodiment and Embodiment 1 is that the hollow glass microspheres in this fire-resistant and heat-insulating coating have not undergone surface treatment.

[0048] Experimental Example 1

[0049] The gas cylinders obtained in Examples 1-5 and Comparative Examples 1-2 were used as experimental groups 1-7 for pressure resistance and fire resistance tests, as detailed below:

[0050] Pressure resistance test: Two parallel samples were taken from each experimental group for parallel water pressure burst test. One group was directly subjected to water pressure burst, and the other group was subjected to a drop test from a height of 1.8m before water pressure burst. The experimental results are shown in Table 1.

[0051] Fire resistance test: Six combustion tubes (passing hydrogen gas) with a diameter of 40 mm were connected in parallel, and the length of the ignition source was ensured to be able to be burned and heated within the entire length of the gas cylinder; the experimental results are shown in Table 2;

[0052] Table 1 - Results of Compression Test

[0053]

[0054]

[0055] As shown in Table 1, the high-pressure gas cylinder containing the fire-resistant and heat-insulating coating of the present invention exhibits good pressure resistance and good impact resistance. This is mainly due to the greatly improved interfacial compatibility and adhesion between the surface-treated hollow glass microspheres and polyamide resin, which makes the coating exhibit better mechanical properties.

[0056] Table 2 - Fire Resistance Test Results

[0057]

[0058]

[0059] As shown in Table 2, the high-pressure gas cylinder containing the fire-resistant and heat-insulating coating of the present invention exhibits good fire-retardant effects. This is mainly due to the preparation of modified resin by copolymerizing epoxy resin matrix with hydroxyl-terminated polydimethylsiloxane, which introduces flexible and high-bond-energy Si-O bonds, making the modified resin have better toughness and higher heat resistance. This is mainly due to the decomposition of modified polyamide resin under thermo-oxidative conditions, which is conducive to the enrichment of silicon elements to form a stable hybrid carbon layer containing silicon, oxygen, and carbon, which hinders the exchange of gas and heat and delays the further decomposition of the matrix.

[0060] Unmodified polyamide resin, i.e., when ordinary polyamide resin is used as a binder, has poor fire resistance and heat insulation. This is mainly because, in the event of a fire, it cannot form a stable hybrid carbon layer containing silicon, oxygen, and carbon on the surface of the gas cylinder to hinder the exchange of gas and heat, and is more easily decomposed, thus resulting in poor fire resistance. Furthermore, the interfacial compatibility and adhesion between untreated hollow glass microspheres and polyamide resin are poor, which reduces the overall fire resistance of the fire-resistant and heat-insulating coating and increases the heat transfer efficiency, thereby reducing the fire resistance and heat insulation performance of the gas cylinder.

[0061] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A fire-resistant and heat-insulating high-pressure gas cylinder, comprising an inner liner, and further comprising a carbon fiber winding layer, a fire-resistant and heat-insulating coating layer, and a high-silica glass fiber fire-resistant layer disposed sequentially from the inside to the outside on the outer surface of the inner liner; The fire-resistant and heat-insulating coating comprises, by weight parts: The composition comprises 5-10 parts hollow glass microspheres, 40-60 parts modified polyamide resin, 1-5 parts film-forming aid, 15-30 parts titanate coupling agent, and 30-50 parts water; the hollow glass microspheres are pre-treated with titanate coupling agent; the modified polyamide resin is a hydroxyl-terminated polydimethylsiloxane-modified polyamide resin.

2. The fire-resistant and heat-insulating high-pressure gas cylinder according to claim 1, characterized in that, The surface treatment method of the hollow glass microspheres is as follows: the hollow glass microspheres are added to an organic solution and mixed, then a titanate coupling agent is added, and after reacting for a period of time, the hollow glass microspheres are obtained by filtration and drying.

3. The fire-resistant and heat-insulating high-pressure gas cylinder according to claim 2, characterized in that, The surface treatment method of the hollow glass microspheres is as follows: the hollow glass microspheres are added to an ethanol solution and mixed evenly, and the reaction temperature is controlled at 50-70℃. Then, 0.2-0.8% of the mass of the hollow glass microspheres of coupling agent is added. After reacting for 1-2 hours, the mixture is cooled to room temperature, filtered, and dried at 100-150℃ for 1-3 hours to obtain the hollow glass microspheres.

4. The fire-resistant and heat-insulating high-pressure gas cylinder according to claim 1, characterized in that, The modified polyamide resin is prepared by mixing polyamide resin and hydroxyl-terminated polydimethylsiloxane evenly, adding oxalic acid, reacting for a period of time, and then slowly adding bismuth isooctanoate dropwise. After the reaction, the modified polyamide resin is obtained.

5. The fire-resistant and heat-insulating high-pressure gas cylinder according to claim 4, characterized in that, The mass ratio of the polyamide resin, hydroxyl-terminated polydimethylsiloxane, oxalic acid, and bismuth isooctanoate is 100-150:30-35:1.5-2:

1.

6. The fire-resistant and heat-insulating high-pressure gas cylinder according to claim 4, characterized in that, After the polyamide resin and hydroxyl-terminated polydimethylsiloxane are mixed evenly, they are heated to 60-90℃ for pre-reaction for 0.5-1h.

7. The fire-resistant and heat-insulating high-pressure gas cylinder according to claim 4, characterized in that, After adding oxalic acid, continue heating to 90-110℃ and react for 0.5-1 hour.

8. The fire-resistant and heat-insulating high-pressure gas cylinder according to claim 4, characterized in that, After adding bismuth isooctanoate, continue heating to 110-130℃ and evacuate for 2 hours.

9. The fire-resistant and heat-insulating high-pressure gas cylinder according to any one of claims 1-8, characterized in that, The preparation method of the fire-resistant and heat-insulating coating includes the following steps: after mixing the film-forming aid and water, add the titanate coupling agent and modified polyamide resin, disperse at high speed, then add the surface-treated hollow glass microspheres, stir evenly, and the fire-resistant and heat-insulating coating is obtained.

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