Preparation method of foamed silica gel strip with high flame retardance

Abstract

The invention discloses a preparation method of a foamed silica gel strip with high flame retardance, the foamed silica gel strip is mainly prepared from silica gel, a flame retardant and a foaming agent as raw materials, the silica gel is a high polymer material formed by mixing silicon dioxide and an organosilicon compound, the organosilicon compound is set to be silane or silicone, and the foaming agent is a foaming agent. The flame retardant is one of aluminum hydroxide, hexavalent chromium, a hexavalent aluminum compound and a nitrogen-phosphorus compound; the preparation method comprises the following steps: mixing silica gel and a flame retardant in proportion, adding a foaming agent into the mixed material to carry out foaming reaction, molding and cooling a foaming structure through a molding press or an extruder, coating the surface of a cooled silica gel primary product with a flame-retardant coating, and drying to obtain the foamed silica gel strip. The flame retardance of the material of the foamed silica gel strip is improved through the flame retardant, the flame-retardant effect of the surface of the foamed silica gel strip is improved through the flame-retardant coating, and the flame retardance of the foamed silica gel strip is effectively improved through combination of the interior and the exterior of the foamed silica gel strip.

Description

Technical Field

[0001] The present invention belongs to the technical field of the preparation of foamed silicone strips, and particularly relates to a method for preparing a highly flame-retardant foamed silicone strip. Background Technique

[0002] The foamed silicone strip is a high-temperature resistant silicone molded product, which has excellent properties such as good oil resistance, corrosion resistance, aging resistance, non-toxic, odorless, and strong elasticity. It is made by adding a foaming agent to 100% gaseous-phase silicone raw materials and vulcanizing them in a high-temperature oven. During the vulcanization process, a large amount of air is generated, causing a large number of small holes to form inside the silicone. It can continuously operate at 300 degrees Celsius without quality change. It can be widely used in new energy vehicles, electromagnetic shielding materials, 5G base stations, high-speed trains, airplanes, electronic appliances, furniture equipment, medical equipment, toys, sports goods, machinery, automobiles, wind power generation, industrial buildings, etc.

[0003] When preparing the foamed silicone strip, polymer materials are usually used for preparation, such as polyurethane, polyethylene, etc. However, these polymer materials themselves have poor flame-retardant properties, are prone to combustion and fire spread, thus affecting the flame-retardant effect of the foamed silicone strip. Therefore, we need to propose a method for preparing a highly flame-retardant foamed silicone strip to solve the above existing problems and effectively improve the flame retardancy of the foamed silicone. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for preparing a highly flame-retardant foamed silicone strip, which improves the flame retardancy of the material of the prepared foamed silicone strip through a flame retardant, and improves its flame-retardant effect on the surface of the foamed silicone strip through a flame-retardant coating. By combining the inside and outside of the foamed silicone strip, the flame retardancy of the foamed silicone strip is effectively improved to solve the problems proposed in the above background technique.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions:

[0006] A method for preparing a highly flame-retardant foamed silicone strip includes the following steps:

[0007] S1. By mass components, prepare the following raw materials: 40-50 parts of silicone, 25-35 parts of flame retardant, and 10-25 parts of foaming agent; wherein, the silicone is a high molecular material formed by mixing silicon dioxide and organosilicon compounds, and the organosilicon compound is set as silane or silicone, and the flame retardant is set as one of aluminum hydroxide, hexavalent chromium, hexavalent aluminum compounds, and nitrogen-phosphorus compounds;

[0008] S2. Place the silicone in a container, add the flame retardant and stir to mix, so that the flame retardant is fully dispersed in the silicone to obtain a mixed material;

[0009] S3. Add a foaming agent to the mixed material and set the foaming parameters to cause the mixed material to generate bubbles and form a foamed structure.

[0010] S4. Shape the foamed structure using a molding press or an extruder and obtain a preliminary silicone strip after cooling.

[0011] S5. Coat the surface of the preliminary silicone strip with a flame retardant coating and obtain the finished foamed silicone product after drying.

[0012] Preferably, in step S1, by mass components, prepare the following raw materials: 45 parts of silicone, 30 parts of flame retardant, 20 parts of foaming agent; wherein, the silicone is a polymer material mixed by silicon dioxide and silane, and the flame retardant is set as aluminum hydroxide.

[0013] Preferably, in step S1, by mass components, prepare the following raw materials: 40 parts of silicone, 25 parts of flame retardant, 10 parts of foaming agent; wherein, the silicone is a polymer material mixed by silicon dioxide and silicone, and the flame retardant is set as hexavalent chromium.

[0014] Preferably, the foaming agent is set as one of polystyrene particles, polymer microspheres, polyethylene particles, polyacrylamide microspheres and polyurethane foam.

[0015] Preferably, the hexavalent aluminum compound reacts to obtain a precipitate of hexavalent aluminate, and the pure hexavalent aluminum compound is obtained through filtration and purification.

[0016] Preferably, the nitrogen-phosphorus compound carries out a chemical reaction to combine phosphorus element and nitrogen element to generate a nitrogen-phosphorus compound.

[0017] Preferably, in step S2, when the silicone is mixed with the flame retardant, a stirrer is required to stir clockwise and counterclockwise alternately to make the flame retardant evenly dispersed in the silicone.

[0018] Preferably, in step S3, the foaming parameters include the air pressure, temperature and humidity of foaming, and the foaming parameters are adjusted according to the compatibility of the flame retardant and the silicone to achieve the best foaming effect.

[0019] Preferably, in step S4, the foamed structure is one of an open pore structure, a closed pore structure, a columnar structure and a spherical structure.

[0020] Preferably, in step S5, the flame retardant coating is one of a phosphorus-based flame retardant coating, a nitrogen-based flame retardant coating and an aluminum-based flame retardant coating.

[0021] A preparation method of a highly flame-retardant foamed silicone strip proposed by the present invention has the following advantages compared with the prior art:

[0022] 1. The present invention is mainly made of silica gel, flame retardant and foaming agent. Among them, the silica gel is a polymer material formed by mixing silicon dioxide and organosilicon compounds. The organosilicon compound is set as silane or silicone, and the flame retardant is set as one of aluminum hydroxide, hexavalent chromium, hexavalent aluminum compounds and nitrogen-phosphorus compounds. First, the silica gel and the flame retardant are mixed in proportion, then the foaming agent is added to the mixed material for foaming reaction, and then the foamed structure is formed and cooled by a molding press or an extruder. Finally, a flame retardant coating is applied to the surface of the initially formed silica gel after cooling, and then dried to obtain a foamed silica gel strip. The flame retardancy of the foamed silica gel strip itself is improved by the flame retardant, and the flame retardant effect of the surface of the foamed silica gel strip is improved by the flame retardant coating. The flame retardancy of the foamed silica gel strip is effectively improved by the combination of the inside and the outside of the foamed silica gel strip. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a flowchart of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0025] Embodiment 1

[0026] The present invention provides a method for preparing a highly flame-retardant foamed silica gel strip as shown in Figure 1 and includes the following steps:

[0027] S1. By mass components, prepare the following raw materials: 45 parts of silica gel, 30 parts of flame retardant, and 20 parts of foaming agent; among them, the silica gel is a polymer material formed by mixing silicon dioxide and organosilicon compounds. The organosilicon compound is set as silane or silicone, and the flame retardant is set as one of aluminum hydroxide, hexavalent chromium, hexavalent aluminum compounds and nitrogen-phosphorus compounds;

[0028] Aluminum hydroxide Aluminum hydroxide is a commonly used inorganic flame retardant, and it can be prepared through the following steps:

[0029] First, react an aluminum salt (such as aluminum chloride, aluminum sulfate, etc.) with sodium hydroxide or ammonium hydroxide. The precipitate produced by the reaction is aluminum hydroxide, and pure aluminum hydroxide particles can be obtained under appropriate conditions (such as filtration, washing, etc.);

[0030] Hexavalent chromium is usually used as a flame retardant in the form of its oxides or compounds, and one common compound is sodium dichromate. The preparation method of sodium dichromate is as follows:

[0031] Mix chromic acid and sodium carbonate and dissolve them in water. After reaction, a solution of sodium dichromate is formed.

[0032] Crystallize, filter, and dry the solution to finally obtain crystalline solids of sodium dichromate;

[0033] Hexavalent aluminum compounds react to obtain precipitates of hexavalent aluminates, which are filtered and purified to obtain pure hexavalent aluminum compounds.

[0034] Nitrogen-phosphorus compounds combine phosphorus and nitrogen elements to form nitrogen-phosphorus compounds, which are usually used as nitrogen-phosphorus-containing flame retardants, such as organophosphorus flame retardants. The specific preparation methods of nitrogen-phosphorus compounds vary for different compounds. A common method for preparing organophosphorus flame retardants is to react compounds containing phosphorus and nitrogen elements, and through appropriate synthesis reactions, nitrogen-phosphorus compounds are formed.

[0035] S2. Place silica gel in a container, add a flame retardant and stir to mix, so that the flame retardant is fully dispersed in the silica gel to obtain a mixed material;

[0036] When mixing silica gel with the flame retardant, a stirrer is needed to stir clockwise and counterclockwise alternately to evenly disperse the flame retardant in the silica gel.

[0037] S3. Add a foaming agent to the mixed material and set foaming parameters to make the mixed material generate bubbles to form a foamed structure;

[0038] The foaming parameters include the air pressure, temperature, and humidity of foaming. When setting the foaming parameters, they are adjusted according to the compatibility parameters of the flame retardant and silica gel for foaming parameters to achieve the best foaming effect. For example, some foaming agents require higher temperatures and pressures to form bubbles. According to the requirements of specific materials, the parameters of the foaming equipment can be adjusted to achieve the best foaming effect.

[0039] The foaming agent is set to one of polystyrene particles, polymer microspheres, polyethylene particles, polyacrylamide microspheres, and polyurethane foam. Polystyrene particles and polymer microspheres are physical / mechanical foaming agents including tiny particles or foams. By mixing them into silica gel and then through shearing or mechanical stirring, foaming is achieved. These particles or foams form a bubble structure in the silica gel, which can produce light and flexible foamed silica gel.

[0040] Polyethylene particles are a type of physical foaming agent with good softness and toughness, and can be used for silicone foaming. They have light characteristics and excellent impact absorption performance. Polyacrylamide microbeads are a type of physical foaming agent with good foaming performance. They can be foamed by mixing the microbeads into silicone and then applying appropriate shear or vibration. Polyurethane foam is a material that can be used as a physical foaming agent in silicone. It has good foaming performance and insulation performance, and can be used to prepare silicone materials with a pore structure.

[0041] S4. Mold the foaming structure using a molding press or an extruder, and obtain a preliminary silicone strip after cooling;

[0042] The foaming structure includes one of an open pore structure, a closed pore structure, a honeycomb structure, and a spherical structure; The open pore structure means that there are connected channels between the bubbles, enabling the bubbles to connect and exchange gases with each other. This structure usually has a relatively large porosity and can provide good heat insulation and sound absorption performance. Common open pore materials include porous polymer foams and some sponge-like materials. The closed pore structure means that there are no connected channels between the bubbles, and each bubble is independently closed. This structure usually has relatively high strength and density, and is suitable for forming lightweight materials or providing buoyancy. For example, closed cell foam materials such as polyurethane. The honeycomb structure means a structure composed of hexagonal or similar-shaped arranged bubbles, similar to the form of a honeycomb. This structure has relatively high strength and stiffness, and performs well in energy absorption and shock absorption.

[0043] The honeycomb structure is commonly found in materials such as aluminum honeycomb panels. The spherical bubble structure means spherical bubbles evenly distributed in the material. The spherical bubble structure is commonly found in some microbead glasses and spherical foam materials.

[0044] S5. Coat the surface of the preliminary silicone strip with a flame retardant coating, and obtain the finished foamed silicone after drying, enhancing its flame retardant effect through the flame retardant coating on the surface of the foamed silicone strip.

[0045] The flame retardant coating includes one of a phosphorus-based flame retardant coating, a nitrogen-based flame retardant coating, and an aluminum-based flame retardant coating. Phosphorus-based flame retardant coatings are a type of commonly used flame retardant coatings, and their main components are phosphorus-containing compounds. Phosphorus compounds can release phosphorus oxides at high temperatures to form a protective layer to prevent the spread of flames. The phosphorus-based flame retardant coating forms a phosphated layer on the surface of the silicone material to play a flame retardant role;

[0046] Nitrogen-based flame retardant coatings often contain nitrogen-containing compounds, and these compounds can inhibit the spread of flames. Nitrogen-based flame retardant coatings provide flame retardant effects by forming a nitrided layer on the surface of the silicone.

[0047] Aluminum-based flame retardant coatings mainly contain aluminum powder or other aluminum compounds, which can form an aluminum oxide layer at high temperatures, achieving heat insulation and flame retardant effects. The aluminum-based flame retardant coatings form an aluminum oxide layer on the silicone surface to provide flame retardant performance.

[0048] Carbon-based flame retardant coatings mainly contain carbon-containing compounds, which can form a charred layer at high temperatures to prevent the spread of flames. The carbon-based flame retardant coatings form a charred layer on the silicone surface to provide flame retardant effects.

[0049] Example 2

[0050] The same parts will not be repeated. Different from Example 1, in step S1, by mass components, prepare the following raw materials: 40 parts of silicone, 25 parts of flame retardant, and 10 parts of foaming agent; among them, the silicone is a polymer material mixed by silicon dioxide and silicone, and the flame retardant is set as hexavalent chromium.

[0051] Example 3

[0052] The same parts will not be repeated. Different from Example 1, prepare the following raw materials: 50 parts of silicone, 35 parts of flame retardant, and 25 parts of foaming agent; among them, the silicone is a polymer material mixed by silicon dioxide and silane, and the flame retardant is set as hexavalent aluminum compound.

[0053] In summary, it is mainly made of silicone, flame retardant and foaming agent. Among them, the silicone is a polymer material mixed by silicon dioxide and organosilicon compounds, and the organosilicon compounds are set as silane or silicone. The flame retardant is set as one of aluminum hydroxide, hexavalent chromium, hexavalent aluminum compounds and nitrogen-phosphorus compounds; first, mix the silicone and the flame retardant in proportion, then add the foaming agent to the mixed material for foaming reaction, then form and cool the foaming structure through a molding press or an extruder, and finally coat the surface of the cooled initial silicone product with a flame retardant coating, and then dry to obtain a foamed silicone strip. The flame retardancy of the made foamed silicone strip itself is improved by the flame retardant, and the flame retardant effect of the surface of the foamed silicone strip is improved by the flame retardant coating. The flame retardancy of the foamed silicone strip is effectively improved by the combination of the inside and outside of the foamed silicone strip.

[0054] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A preparation method of a highly flame-retardant foamed silicone strip, characterized in that: It includes the following steps: S1. Prepare the following raw materials by mass components: 40-50 parts of silica gel, 25-35 parts of flame retardant, and 10-25 parts of foaming agent; wherein, the silica gel is a polymer material mixed by silicon dioxide and organosilicon compound, the organosilicon compound is set as silane or silicone, and the flame retardant is set as one of aluminum hydroxide, hexavalent chromium, hexavalent aluminum compound and nitrogen-phosphorus compound; S2. Place the silica gel in a container, add the flame retardant and stir and mix to make the flame retardant fully dispersed in the silica gel to obtain a mixed material; S3. Add the foaming agent to the mixed material and set the foaming parameters to make the mixed material generate bubbles to form a foaming structure; S4. Mold the foaming structure through a molding press or an extruder and obtain a preliminary product of silica gel strip after cooling; S5. Coat the surface of the preliminary product of silica gel strip with a flame retardant coating and obtain a finished foamed silica gel after drying.

2. The preparation method of a highly flame-retardant foamed silicone strip according to claim 1, wherein: In step S1, prepare the following raw materials by mass components: 45 parts of silica gel, 30 parts of flame retardant, and 20 parts of foaming agent; wherein, the silica gel is a polymer material mixed by silicon dioxide and silane, and the flame retardant is set as aluminum hydroxide.

3. The preparation method of a highly flame-retardant foamed silica gel strip according to claim 1, characterized in that: In step S1, prepare the following raw materials by mass components: 40 parts of silica gel, 25 parts of flame retardant, and 10 parts of foaming agent; wherein, the silica gel is a polymer material mixed by silicon dioxide and silicone, and the flame retardant is set as hexavalent chromium.

4. The preparation method of a highly flame-retardant foamed silica gel strip according to claim 2 or 3, characterized in that: The foaming agent is set as one of polystyrene particles, polymer microspheres, polyethylene particles, polyacrylamide microspheres and polyurethane foam.

5. The preparation method of a highly flame-retardant foamed silica gel strip according to claim 4, characterized in that: The hexavalent aluminum compound reacts to obtain a precipitate of hexavalent aluminate, and is filtered and purified to obtain a pure hexavalent aluminum compound.

6. The preparation method of a highly flame-retardant foamed silicone strip according to claim 5, characterized in that: The nitrogen-phosphorus compound carries out a chemical reaction on phosphorus element and nitrogen element to generate a nitrogen-phosphorus compound.

7. The preparation method of a highly flame-retardant foamed silica gel strip according to claim 6, characterized in that: In step S2, when the silica gel is mixed with the flame retardant, a stirrer is required to stir clockwise and counterclockwise alternately to make the flame retardant evenly dispersed in the silica gel.

8. The preparation method of a highly flame-retardant foamed silicone strip according to claim 7, characterized in that: In step S3, the foaming parameters include the air pressure, temperature and humidity of foaming. When setting the foaming parameters, they are adjusted according to the compatibility of the flame retardant and the silica gel to make the foaming effect reach the best.

9. The preparation method of a highly flame-retardant foamed silicone strip according to claim 8, characterized in that: In step S4, the foaming structure includes one of an open pore structure, a closed pore structure, a columnar structure and a spherical structure.

10. The preparation method of a highly flame-retardant foamed silicone strip according to claim 9, characterized in that: In step S5, the flame retardant coating includes one of a phosphorus-based flame retardant coating, a nitrogen-based flame retardant coating and an aluminum-based flame retardant coating.

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