Clustered mullite fiber attached with surface coating and preparation method of surface coating of clustered mullite fiber

Abstract

The invention discloses a clustered mullite fiber attached with a surface coating and a preparation method of the surface coating of the clustered mullite fiber, and the preparation method comprises the following steps: preparing first coating slurry which comprises mullite sol; preparing second coating slurry, wherein the second coating slurry comprises a high-molecular polymer and silica sol; preparing third coating slurry, wherein the third coating slurry comprises an antistatic agent and a softener; the preparation method comprises the following steps: dipping a fiber bundle in first coating slurry and drying for the first time, then dipping in second coating slurry and drying for the second time, and then dipping in third coating slurry and drying for the third time to obtain clustered mullite fiber and a surface coating attached to the surface of the mullite fiber; according to the invention, the coating is attached to the surface of the mullite fiber, damage repair of the surface of the mullite fiber is realized, the bundled mullite fiber bundle does not fluff in the use process, and organic components in the coating are easy to remove at 300-600 DEG C before use.

Description

Technical Field

[0001] The invention relates to the field of mullite fibers, in particular to the field of bundled mullite fibers with attached surface coatings and a method for preparing the surface coatings thereof. Background Art

[0002] Mullite fiber has excellent properties such as high temperature resistance, oxidation resistance, thermal shock resistance, chemical corrosion resistance, and electrical insulation, and can be widely used in aerospace, industrial high-temperature furnaces, petrochemicals, environmental protection, etc. Sizing is an important process in the production of high-performance mullite fiber.

[0003] During the preparation process, mullite fiber often suffers surface damage due to mechanical scratches on the surface and friction between the roller and the fiber surface or between fibers. Mullite fiber needs to be bundled before use before weaving. After weaving, the coating needs to be removed during other processes such as impregnation. However, the thicker the surface coating of the mullite fiber after bundling, the more difficult it will be to remove the coating later. When the surface coating of the mullite fiber is thin after bundling, fuzzing will occur during use.

[0004] Therefore, how to attach a coating on the surface of mullite fiber to repair the damage on the surface of mullite fiber, and how to prevent the bundled mullite fiber bundles from fuzzing during use, and how to easily remove the organic components in the coating at 300-600°C before use, are the difficulties in preparing the sizing coating. Summary of the invention

[0005] The purpose of the present invention is to provide a bundled mullite fiber with attached surface coating and a method for preparing the surface coating thereof, so as to achieve the attachment of coating on the surface of mullite fiber and the repair of surface damage of mullite fiber, and the bundled mullite fiber bundle will not fuzz during use, and the organic components in the coating can be easily removed at 300-600°C before use.

[0006] One aspect of the present invention provides a method for preparing a surface coating of a mullite fiber, comprising the following steps:

[0007] preparing a first coating slurry, wherein the first coating slurry includes mullite sol;

[0008] preparing a second coating slurry, wherein the second coating slurry comprises a high molecular polymer and silica sol;

[0009] preparing a third coating slurry, wherein the third coating slurry comprises an antistatic agent and a softener;

[0010] The fiber bundle is sequentially and continuously immersed in the first coating slurry, the second coating slurry, and the third coating slurry in sequence, and the surface coating is attached to the surface of the fiber bundle;

[0011] The fiber bundle is impregnated with a first coating slurry and dried for the first time, then impregnated with a second coating slurry and dried for the second time, and then impregnated with a third coating slurry and dried for the third time to obtain a bundled mullite fiber and a surface coating attached to the surface of the mullite fiber;

[0012] The first drying, the second drying and the third drying temperatures are all 60-100°C.

[0013] The beneficial effect of the present invention over the prior art is that, by sequentially and continuously immersing the fiber bundle in the first coating slurry, the second coating slurry, and the third coating slurry, a surface coating precursor is attached to the surface of the fiber bundle, so that the surface coating of the mullite fiber bundle includes a three-layer structure of an inner coating layer, an intermediate coating layer, and an outer coating layer;

[0014] The first coating slurry includes mullite sol, so that the inner coating of the mullite fiber surface coating contains mullite components, thereby achieving high bonding strength between the mullite fiber surface coating and the mullite fiber, and repairing the damage on the surface of the mullite fiber;

[0015] Through the second coating slurry, the second coating slurry includes a high molecular polymer and silica sol, that is, the inner coating, outer coating and middle coating of the surface coating of the mullite fiber bundle have high bonding strength, so as to achieve high overall strength of the surface coating of the mullite fiber bundle, and when the organic components in the coating are removed by heating during the subsequent impregnation process, the distance between the middle coating and the outer coating is small and very easy to volatilize, and the outer coating naturally detaches while the middle coating volatilizes; the inner coating does not need to be detached, and the mullite sol contained in it is combined with the mullite fiber in the subsequent sintering process to improve the smoothness and strength of the mullite fiber;

[0016] Through the third coating slurry, the third coating slurry includes an antistatic agent and a softener, so that the surface of the mullite fiber bundle is smooth and has antistatic properties, which is further conducive to avoiding the problem of fuzzing of the mullite fiber bundle during use before weaving;

[0017] Therefore, the mullite fibers can be bundled and the bundled mullite fibers will not fuzz during use, and the organic components in the coating can be easily removed at 300-600° C. before use.

[0018] Furthermore, the first coating slurry preparation method comprises the following steps:

[0019] preparing a mullite sol;

[0020] Add silane coupling agent to mullite sol, mix at 25-45°C, stir at 45-80°C for 0.5-3h to obtain first coating slurry; the amount of silane coupling agent added is 0.5-3% of the mass fraction of mullite sol.

[0021] The solid content of the first coating slurry is 10-15%;

[0022] The sol particle size in the first coating slurry is 50-200 nm.

[0023] The silane coupling agent includes: one of an amino silane coupling agent and a vinyl silane coupling agent.

[0024] The beneficial effect of the above step is that the inner coating of the surface coating of the mullite fiber bundle formed by the first coating slurry is evenly combined with the second coating slurry by adding a silane coupling agent to the mullite sol, and the inner coating of the surface coating of the mullite fiber bundle is highly bonded to the middle coating;

[0025] The solid content of the first coating slurry is 10-15%, so that the coating strength is relatively high, which is conducive to avoiding the problem of fiber bundles fuzzing during use;

[0026] The sol particle size in the first coating slurry is 50-200nm, which is further conducive to the inner layer coating strength of the mullite fiber bundle surface coating being high, and the inner layer coating surface being rough, which is conducive to high bonding strength with the intermediate layer coating of the mullite fiber bundle surface coating.

[0027] Furthermore, the mullite sol preparation process comprises the following steps:

[0028] The mullite sol preparation process comprises:

[0029] Modifying a silica sol having a solid content of 10-15% by means of a carboxylic acid, adjusting the pH to 2-3, and stirring at 30-50° C. for 3-5 hours to obtain a modified silica sol;

[0030] The modified silica sol and 10-15% acidic aluminum sol are mixed in a mass ratio of 1:(2.5-4.5), and stirred at 40-80° C. for 5-10 hours to prepare a mullite sol.

[0031] The beneficial effect of the previous step is that by modifying the silica sol with a solid content of 10-15% by carboxylic acid, it is conducive to achieving uniform dispersion of the first coating slurry and the surface of the mullite fiber and the first coating slurry has a certain viscosity, thereby achieving uniform adhesion of the first coating slurry to the surface of the mullite fiber.

[0032] Furthermore, the second coating slurry preparation method comprises the following steps:

[0033] Mixing a high molecular polymer with deionized water, with a mass fraction of the high molecular polymer being 0.5-3%, stirring at 70-90° C. for 60-120 minutes, and then cooling the temperature to room temperature to obtain a high molecular polymer solution;

[0034] The prepared high molecular polymer solution is mixed with ethanol and silica sol, the mass ratio of the high molecular polymer solution to ethanol is 1: (0.5-1.5), and the mass ratio of the high molecular polymer solution to silica sol with a solid content of 10-15% is 1: (0.1-0.3), and then stirred at 35-55° C. for 30-60 minutes to obtain a polymer silica sol mixed solution;

[0035] Add an emulsifier to the polymer silica sol mixed solution, stir at 45-55° C. for 60-120 minutes to obtain a second coating slurry;

[0036] The emulsifier accounts for 0.1-1% by mass of the polymer silica sol mixed solution;

[0037] The emulsifier includes one or more of sodium dodecyl sulfonate, sodium dodecylbenzene sulfonate, and sodium dodecyl sulfonate.

[0038] The beneficial effect of the above step is that the polymer solution is mixed with ethanol and silica sol to achieve uniform mixing of the polymer and silica sol, and the third coating slurry and the surface of the intermediate coating are evenly dispersed and the intermediate coating has a high bonding strength with the outer coating.

[0039] By adding an emulsifier to the polymer silica sol mixture, it is further beneficial to mix the second coating slurry evenly and improve fluidity, while achieving uniform dispersion of the second coating slurry on the surface of the outer coating layer and high bonding strength between the intermediate coating layer and the inner coating layer.

[0040] Further, the solid content of the second coating slurry is 0.5-5.0%;

[0041] The particle size of the sol in the second coating slurry is 10-30 nm.

[0042] The beneficial effect of adopting the previous step is that the thickness of the intermediate layer coating of the mullite fiber surface coating is thin, and when the coating is subsequently heated to be removed, the intermediate layer coating is easy to detach, and the sol particle size in the second coating slurry is small, which is conducive to achieving a high bonding strength between the intermediate layer coating and the inner layer coating and is conducive to improving the surface smoothness of the mullite fiber surface coating.

[0043] Furthermore, the third coating slurry preparation method comprises the following steps:

[0044] The antistatic agent, the softener and the deionized water are mixed in a mass ratio of 1:1:(99.0-99.9), and stirred at 45-55° C. for 60-120 minutes to obtain the third coating slurry;

[0045] The antistatic agent includes one or more of lauryl alcohol polyoxyethylene ether phosphate potassium salt, hexadecanol sulfate methyl salt, and octadecyl dihydroxyethyl betaine;

[0046] The softener includes one or more of sodium lauryl sulfate, sodium fatty alcohol polyoxyethylene ether sulfate, and sodium sulfosuccinate.

[0047] The beneficial effect of adopting the previous step is that the outer coating of the mullite fiber surface coating prepared by the third coating slurry has high smoothness and antistatic properties, thereby achieving a smooth surface and antistatic properties of the mullite fiber surface coating;

[0048] At the same time, by mixing the antistatic agent, softener and deionized water in a mass ratio of 1:1:(99.0-99.9), the outer coating of the mullite fiber surface coating is thin, which is further conducive to heating and removing organic components in the surface coating before use.

[0049] Furthermore, the second coating slurry also includes paraffin wax;

[0050] The polymer and deionized water are mixed in a mass ratio, stirred at 70-90° C. for 60-120 minutes, and then paraffin is added, and the stirring is continued for 10-30 minutes to obtain a polymer solution, which is maintained at 50-70° C. for standby use; the mass ratio of the polymer, paraffin and deionized water is 1:(0.3-1.2):(0.5-1.5);

[0051] The prepared high molecular polymer solution is mixed with ethanol and silica sol at 55-65°C, the mass ratio of the high molecular polymer solution to ethanol is 1:(0.5-1.5), and the mass ratio of the high molecular polymer solution to silica sol with a solid content of 10-15% is 1:(0.1-0.3), and then stirred at 55-65°C for 30-60 minutes to obtain a polymer silica sol mixed solution;

[0052] An emulsifier is added to the polymer silica sol mixed solution, and stirred at 55-65° C. for 60-120 minutes to obtain a second coating slurry; the emulsifier accounts for 0.1-1% of the mass fraction of the polymer silica sol mixed solution; and the mixture is maintained at 50-65° C. for standby use.

[0053] The beneficial effect of adopting the previous step is that by also including paraffin in the second coating slurry, it is beneficial to improve the bonding strength between the intermediate coating of the surface coating and the outer coating and the inner coating respectively, and it is beneficial to heat and remove the organic components in the surface coating before use.

[0054] Further, the process of attaching the surface coating to the surface of the fiber bundle includes the following steps:

[0055] The fiber bundle is sequentially impregnated with a first coating slurry, a second coating slurry, and a third spraying slurry through a continuous impregnation and drying device;

[0056] The continuous impregnation and drying device comprises a first impregnation device, a first continuous drying device, a second impregnation device, a second continuous drying device, a third impregnation device, and a third continuous drying device;

[0057] The first impregnation device continuously impregnates the surface of the fiber bundle with the first coating slurry and then performs the first drying through the first continuous drying device; the second impregnation device continuously impregnates the fiber bundle with the second coating slurry and then performs the second drying through the second continuous drying device; the third spraying slurry continuously sprays the fiber bundle with the third coating slurry and then performs the third drying; the bundled mullite fibers and the surface coating attached to the surface of the mullite fibers are obtained.

[0058] The beneficial effect of adopting the previous step is to achieve continuous attachment of surface coating to mullite fiber, and the continuously attached surface coating includes inner coating, middle coating and outer coating of the surface coating formed by first coating slurry, second coating slurry and third coating slurry respectively from inside to outside.

[0059] Further, the first impregnation device includes a first container, a first support roller A, a plurality of first support rollers B, a plurality of first pressure rollers A, a first pressure roller B, and a first support roller C;

[0060] The first support roller A and the first support roller B are located below the fiber bundle, and the first pressing roller A and the first pressing roller B are located above the fiber bundle; the plurality of first support rollers B, the first pressing roller A, and the first pressing roller B are located between the first support roller A and the first support roller B;

[0061] The first support roller A and the first support roller C are located above the highest point of the continuous fiber matrix impregnation device;

[0062] The first support roller B and the first pressing roller A are located inside the dipping compound container, and part or all of the first support roller B and the first pressing roller A are located below the surface of the first coating slurry inside the first container;

[0063] The first pressing roller B is located between the first pressing roller A and the first supporting roller C;

[0064] The first pressing roller A and the first supporting roller B are arranged opposite to each other, and the fiber bundle passes between the first pressing roller A and the first supporting roller B;

[0065] and / or

[0066] The second impregnation device comprises a second container, a second pressing roller A, a second supporting roller A, a second supporting roller B, and n second supporting rollers C, where n≥4; a second coating slurry is arranged in the second container; the second supporting roller A is located outside the second container, higher than the second container, located above the second container, and located on the side of the second container close to the first impregnation device; the second supporting roller B is located outside the second container, higher than the second container, and located above one end of the second container close to the continuous drying device; the n second supporting rollers C are all located inside the second container, divided into two columns A and B, and the third supporting rollers in each column are arranged in sequence from top to bottom in the second container; the second supporting rollers C in column A are located on the side of the second container close to the connection and modification device, and the second supporting rollers C in column B are located on the side of the second container close to the connection and drying device, and the second pressing roller A is located inside the second container, inside the second container close to the drying device, and the height of the second pressing roller A is not higher than the lowest height of the second supporting rollers C in column B;

[0067] and / or

[0068] The third slurry spraying device includes a first lifting device, a spraying device A, a first spraying bracket, a spraying device B, a second spraying bracket, a spraying device C, a third spraying bracket, and a recovery container;

[0069] The first lifting device comprises a first lifting bracket, a first lifting roller, a second lifting roller, and a first lifting support roller at an angle of 60-90 degrees to the ground; the first lifting roller and the first lifting support roller are rotatably connected to the first lifting bracket, and the second lifting roller is rotatably connected to the first lifting bracket or the second recovery container;

[0070] The first spray bracket is rotatably connected to the first spray support roller A and the first spray pressure roller B;

[0071] The second spray bracket is rotatably connected to the second spray support roller A and the second spray pressure roller B;

[0072] The third spray bracket is rotatably connected to the second spray support roller A and the second spray pressure roller B;

[0073] The spray device A is arranged opposite to the first spray bracket, the spray device B is arranged opposite to the second spray bracket, and the spray device C is arranged opposite to the third spray bracket;

[0074] and / or

[0075] The first continuous drying device comprises a first drying roller A, a first drying roller B, a first box, and a first heat source and a first drying conveyor belt located inside the first box;

[0076] The first drying roller A and the first drying roller B are located outside the first box;

[0077] and / or

[0078] The second continuous drying device comprises a second drying roller A, a second drying roller B, a second box, and a second heat source and a second drying conveyor belt located inside the second box;

[0079] The second drying roller A and the second drying roller B are located outside the second box;

[0080] and / or

[0081] The third continuous drying device comprises a third drying roller A, a third drying roller B, a third box, and a third heat source and a third drying conveyor belt located inside the third box;

[0082] The third drying roller A and the third drying roller B are located outside the third box.

[0083] Preferably, the fiber bundle wire feeding speed is 0.1-0.5 m / min, and the lengths of the first drying conveyor belt, the second drying conveyor belt and the third drying conveyor belt are all 3-10 m.

[0084] The beneficial effect of the above step is that the fiber bundle surface is continuously impregnated with the first coating slurry and then dried for the first time by the first continuous drying device, the fiber bundle is continuously impregnated with the second coating slurry by the second impregnating device and then dried for the second time by the second continuous drying device, and the fiber bundle is continuously sprayed with the third coating slurry by the third spraying slurry and then dried for the third time; the bundled mullite fibers and the surface coating attached to the surface of the mullite fibers are obtained;

[0085] Achieve uniformity of the first coating slurry, the second coating slurry, and the third coating slurry to which the fiber bundle is sequentially attached;

[0086] What is ultimately important is that the length of the overall equipment is greatly reduced, which is conducive to the promotion of industrial production.

[0087] Another aspect of the present invention provides a method for preparing a mullite fiber surface coating according to any one of claims 1 to 9; the mass of the surface coating of the bundled mullite fiber with the surface coating is 0.8-2% of the total mass of the bundled mullite fiber;

[0088] The average tensile strength of the bundled mullite fibers of the surface coating is 2.0-2.2 GPa.

[0089] Compared with the prior art, the invention has the advantage that the surface coating of the mullite fiber bundle comprises a three-layer structure of an inner coating, an intermediate coating and an outer coating;

[0090] The first coating slurry includes mullite sol, so that the inner layer coating of the bundled mullite fiber surface coating has a high bonding strength with the mullite fiber, and at the same time, the damage on the surface of the mullite fiber is repaired;

[0091] The inner coating, outer coating and middle coating of the surface coating of the mullite fiber bundle have high bonding strength, so that the overall strength of the surface coating of the mullite fiber bundle is high. When the organic components in the coating are removed by heating in the subsequent impregnation process, the distance between the middle coating and the outer coating is small and very easy to volatilize. The outer coating naturally detaches while the middle coating volatilizes. The inner coating does not need to be detached, and the mullite sol contained in it is combined with the mullite fiber in the subsequent sintering process to improve the smoothness and strength of the mullite fiber. The surface of the inner coating is smooth and antistatic, so that the surface of the mullite fiber bundle is smooth and has antistatic properties. The thin thickness of the outer coating is conducive to heating and removal in subsequent use.

[0092] Therefore, the mullite fibers can be bundled and the bundled mullite fibers will not fuzz during use, and the organic components in the coating can be easily removed at 300-600° C. before use. BRIEF DESCRIPTION OF THE DRAWINGS

[0093] Figure 1 This is the SEM image of the fiber of Example 1 before sizing;

[0094] Figure 2 This is the SEM image of the fiber bundle after sizing of the fiber in Example 1;

[0095] Figure 3 This is a SEM picture of the sized fiber bundle in Example 1 after the coating is removed at 350°C. DETAILED DESCRIPTION

[0096] In order to better understand the technical solution of the present invention, the present invention is further described below in conjunction with specific embodiments and the accompanying drawings of the specification.

[0097] Embodiment 1:

[0098] One aspect of the present embodiment provides a method for preparing a surface coating of a mullite fiber, comprising the following steps:

[0099] preparing a first coating slurry, wherein the first coating slurry includes mullite sol;

[0100] The method for preparing the first coating slurry comprises the following steps: preparing a mullite sol;

[0101] Add silane coupling agent to mullite sol, the mixing temperature is 35°C, stir at 123°C for 1.8h to obtain the first coating slurry; the amount of silane coupling agent added is 1.8% of the mass fraction of mullite sol. The solid content of the first coating slurry is 13%; the sol particle size in the first coating slurry is 125nm. The silane coupling agent is N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane coupling agent;

[0102] The mullite sol preparation process comprises: modifying a silica sol with a solid content of 13% by carboxylic acid, adjusting the pH to 2.5, and stirring at 40° C. for 4 hours to obtain a modified silica sol;

[0103] The modified silica sol and 13% acidic aluminum sol were mixed in a mass ratio of 1:1.8 and stirred at 60° C. for 8 h to prepare a mullite sol.

[0104] A second coating slurry is prepared, wherein the second coating slurry includes a high molecular polymer and a silica sol; and the method for preparing the second coating slurry includes the following steps:

[0105] Mixing a high molecular polymer with deionized water, with a mass fraction of the high molecular polymer being 0.5-3%, stirring at 80° C. for 90 minutes, and then cooling the temperature to room temperature to obtain a high molecular polymer solution;

[0106] The prepared high molecular polymer solution is mixed with ethanol and silica sol, the mass ratio of the high molecular polymer solution to ethanol is 1:1, and the mass ratio of the high molecular polymer solution to silica sol with a solid content of 10-15% is 1:0.65, and then stirred at 45°C for 45 minutes to obtain a polymer silica sol mixed solution;

[0107] An emulsifier is added to the polymer silica sol mixed solution, and the mixture is stirred at 50° C. for 80 minutes to obtain a second coating slurry;

[0108] The emulsifier accounts for 0.6% of the mass fraction of the polymer silica sol mixed solution;

[0109] The emulsifier includes sodium dodecyl sulfate;

[0110] The solid content of the second coating slurry is 2.53%; the sol particle size in the second coating slurry is 20 nm.

[0111] Prepare a third coating slurry, wherein the third coating slurry includes an antistatic agent and a softener; the method for preparing the third coating slurry includes the following steps:

[0112] The antistatic agent, softener and deionized water were mixed in a mass ratio of 1:1:99.5, and stirred at 50° C. for 80 minutes to obtain the third coating slurry;

[0113] The antistatic agent includes hexadecanol methyl sulfate;

[0114] The softener includes sodium lauryl sulfate.

[0115] The fiber bundle is sequentially and continuously immersed in the first coating slurry, the second coating slurry, and the third coating slurry in sequence, and the surface coating is attached to the surface of the fiber bundle;

[0116] The fiber bundle is impregnated with a first coating slurry and dried for the first time, then impregnated with a second coating slurry and dried for the second time, and then impregnated with a third coating slurry and dried for the third time to obtain a bundled mullite fiber and a surface coating attached to the surface of the mullite fiber;

[0117] The process of attaching a surface coating to the fiber bundle surface includes the following steps:

[0118] The fiber bundle is sequentially impregnated with a first coating slurry, a second coating slurry, and a third spraying slurry through a continuous impregnation and drying device;

[0119] The continuous impregnation and drying device comprises a first impregnation device, a first continuous drying device, a second impregnation device, a second continuous drying device, a third impregnation device, and a third continuous drying device;

[0120] The first impregnation device continuously impregnates the surface of the fiber bundle with the first coating slurry and then performs the first drying through the first continuous drying device; the second impregnation device continuously impregnates the fiber bundle with the second coating slurry and then performs the second drying through the second continuous drying device; the third spraying slurry continuously sprays the fiber bundle with the third coating slurry and then performs the third drying; the bundled mullite fibers and the surface coating attached to the surface of the mullite fibers are obtained.

[0121] The first impregnation device comprises a first container, a first supporting roller A, a plurality of first supporting rollers B, a plurality of first pressing rollers A, a first pressing roller B, and a first supporting roller C;

[0122] The first support roller A and the first support roller B are located below the fiber bundle, and the first pressing roller A and the first pressing roller B are located above the fiber bundle; the plurality of first support rollers B, the first pressing roller A, and the first pressing roller B are located between the first support roller A and the first support roller B;

[0123] The first support roller A and the first support roller C are located above the highest point of the continuous fiber matrix impregnation device;

[0124] The first support roller B and the first pressing roller A are located inside the dipping compound container, and part or all of the first support roller B and the first pressing roller A are located below the surface of the first coating slurry inside the first container;

[0125] The first pressing roller B is located between the first pressing roller A and the first supporting roller C;

[0126] The first pressing roller A and the first supporting roller B are arranged opposite to each other, and the fiber bundle passes between the first pressing roller A and the first supporting roller B;

[0127] The second impregnation device comprises a second container, a second pressing roller A, a second supporting roller A, a second supporting roller B, and n second supporting rollers C, where n≥4; a second coating slurry is arranged in the second container; the second supporting roller A is located outside the second container, higher than the second container, located above the second container, and located on the side of the second container close to the first impregnation device; the second supporting roller B is located outside the second container, higher than the second container, and located above one end of the second container close to the continuous drying device; the n second supporting rollers C are all located inside the second container, divided into two columns A and B, and the third supporting rollers in each column are arranged in sequence from top to bottom in the second container; the second supporting rollers C in column A are located on the side of the second container close to the connection and modification device, and the second supporting rollers C in column B are located on the side of the second container close to the connection and drying device, and the second pressing roller A is located inside the second container, inside the second container close to the drying device, and the height of the second pressing roller A is not higher than the lowest height of the second supporting rollers C in column B;

[0128] The third slurry spraying device includes a first lifting device, a spraying device A, a first spraying bracket, a spraying device B, a second spraying bracket, a spraying device C, a third spraying bracket, and a recovery container;

[0129] The first lifting device comprises a first lifting bracket, a first lifting roller, a second lifting roller, and a first lifting support roller at an angle of 60-90 degrees to the ground; the first lifting roller and the first lifting support roller are rotatably connected to the first lifting bracket, and the second lifting roller is rotatably connected to the first lifting bracket or the second recovery container;

[0130] The first spray bracket is rotatably connected to the first spray support roller A and the first spray pressure roller B;

[0131] The second spray bracket is rotatably connected to the second spray support roller A and the second spray pressure roller B;

[0132] The third spray bracket is rotatably connected to the second spray support roller A and the second spray pressure roller B;

[0133] The spray device A is arranged opposite to the first spray bracket, the spray device B is arranged opposite to the second spray bracket, and the spray device C is arranged opposite to the third spray bracket;

[0134] The first continuous drying device comprises a first drying roller A, a first drying roller B, a first box, and a first heat source and a first drying conveyor belt located inside the first box;

[0135] The first drying roller A and the first drying roller B are located outside the first box;

[0136] The second continuous drying device comprises a second drying roller A, a second drying roller B, a second box, and a second heat source and a second drying conveyor belt located inside the second box;

[0137] The second drying roller A and the second drying roller B are located outside the second box;

[0138] The third continuous drying device comprises a third drying roller A, a third drying roller B, a third box, and a third heat source and a third drying conveyor belt located inside the third box;

[0139] The third drying roller A and the third drying roller B are located outside the third box.

[0140] The fiber bundle wire feeding speed is 0.8 m / min, and the lengths of the first drying conveyor belt, the second drying conveyor belt and the third drying conveyor belt are all 7 m.

[0141] The first drying, the second drying and the third drying temperatures are all 80°C.

[0142] Another aspect of the present invention provides a bundled mullite fiber with a surface coating attached thereto.

[0143] The method for preparing a mullite fiber surface coating is used; the mass of the surface coating of the bundled mullite fiber with the surface coating is 1.4% of the total mass of the bundled mullite fiber;

[0144] The average tensile strength of mullite fiber before sizing is 1.98 GPa; the average tensile strength of bundled mullite fiber with surface coating is 2.1 GPa; the organic components in the surface coating are removed at 350°C before use. SEM images of the fiber surface before and after removal are shown in the attached Figure 1 .

[0145] Embodiment 2:

[0146] The same contents as those in Example 1 are not described in detail here. The differences between this embodiment and Example 1 are as follows:

[0147] One aspect of the present embodiment provides a method for preparing a surface coating of a mullite fiber, further comprising the following steps:

[0148] Add silane coupling agent to mullite sol, the mixing temperature is 43°C, stir at 78°C for 2.8h to obtain the first coating slurry; the amount of silane coupling agent added is 2.8% of the mass fraction of mullite sol. The solid content of the first coating slurry is 14.6%; the sol particle size in the first coating slurry is 185nm. The silane coupling agent is vinyl triethoxy silane coupling agent;

[0149] The mullite sol preparation process comprises: modifying a silica sol having a solid content of 14.6% by carboxylic acid, adjusting the pH to 2.8, and stirring at 48° C. for 4.8 hours to obtain a modified silica sol;

[0150] The modified silica sol and 14.6% acidic aluminum sol were mixed in a mass ratio of 1:3.5 and stirred at 79° C. for 5.2 h to prepare a mullite sol.

[0151] The polymer was mixed with deionized water, the mass fraction of the polymer was 2.8%, and stirred at 89° C. for 118 minutes, and then the temperature was lowered to room temperature to obtain a polymer solution;

[0152] The prepared high molecular polymer solution is mixed with ethanol and silica sol, the mass ratio of the high molecular polymer solution to ethanol is 1:1.3, and the high molecular polymer solution and solid content are 13 minutes to obtain a polymer silica sol mixed solution;

[0153] An emulsifier is added to the polymer silica sol mixed solution, and the mixture is stirred at 53° C. for 118 minutes to obtain a second coating slurry;

[0154] The emulsifier accounts for 0.95% of the mass fraction of the polymer silica sol mixed solution;

[0155] The emulsifier includes sodium dodecylbenzene sulfonate;

[0156] The solid content of the second coating slurry is 4.8%; the sol particle size in the second coating slurry is 28 nm.

[0157] Prepare a third coating slurry, wherein the third coating slurry includes an antistatic agent and a softener; the method for preparing the third coating slurry includes the following steps:

[0158] The antistatic agent, softener and deionized water are mixed in a mass ratio of 1:1:99.8, and stirred at 53° C. for 60-120 minutes to obtain the third coating slurry;

[0159] The antistatic agent includes hexadecyl sulfate methyl salt; the softener includes fatty alcohol polyoxyethylene ether sodium sulfate.

[0160] The fiber bundle wire feeding speed is 0.46 m / min, and the lengths of the first drying conveyor belt, the second drying conveyor belt and the third drying conveyor belt are all 4 m.

[0161] The first drying, the second drying and the third drying temperatures are all 98°C.

[0162] Another aspect of the present invention provides a bundled mullite fiber with a surface coating attached thereto.

[0163] The mass of the surface coating of the bundled mullite fibers with attached surface coating is 1.8% of the total mass of the bundled mullite fibers;

[0164] The average tensile strength of the mullite fiber before sizing is 2.0 GPa; the average tensile strength of the bundled mullite fiber with surface coating is 2.18 GPa; the organic components in the surface coating are removed at 450° C. before use.

[0165] Embodiment 3:

[0166] The same contents as those in Example 1 are not described in detail here. The differences between this embodiment and Example 1 are as follows:

[0167] One aspect of the present embodiment provides a method for preparing a surface coating of a mullite fiber, further comprising the following steps:

[0168] Add silane coupling agent to mullite sol, the mixing temperature is 28°C, stir at 48°C for 1h to obtain the first coating slurry; the amount of silane coupling agent added is 1% of the mass fraction of mullite sol. The solid content of the first coating slurry is 11%; the sol particle size in the first coating slurry is 60nm. The silane coupling agent includes: vinyl silane coupling agent;

[0169] The mullite sol preparation process comprises: modifying a silica sol with a solid content of 11% by carboxylic acid, adjusting the pH to 2.2, and stirring at 32° C. for 3.5 hours to obtain a modified silica sol;

[0170] The modified silica sol and 11% acidic aluminum sol were mixed in a mass ratio of 1:2.8 and stirred at 45° C. for 6 h to prepare a mullite sol.

[0171] The second coating slurry also includes paraffin wax;

[0172] The polymer and deionized water were mixed in a mass ratio, stirred at 80°C for 90 minutes, and then paraffin was added and stirred for 20 minutes to obtain a polymer solution, which was maintained at 60°C for standby use; the mass ratio of the polymer, paraffin and deionized water was 1:0.4:0.6;

[0173] The prepared high molecular polymer solution was mixed with ethanol and silica sol at 58°C, the mass ratio of the high molecular polymer solution to ethanol was 1:0.7, and the mass ratio of the high molecular polymer solution to silica sol with a solid content of 11% was 1:0.15, and then stirred at 58°C for 35 minutes to obtain a polymer silica sol mixed solution;

[0174] Add an emulsifier to the polymer silica sol mixed solution, stir at 58° C. for 70 minutes to obtain a second coating slurry; the emulsifier accounts for 0.15% of the mass fraction of the polymer silica sol mixed solution; maintain the temperature at 53° C. for standby;

[0175] The emulsifier includes sodium dodecyl sulfate;

[0176] The solid content of the second coating slurry is 0.85%; the sol particle size in the second coating slurry is 12 nm.

[0177] Prepare a third coating slurry, wherein the third coating slurry includes an antistatic agent and a softener; the method for preparing the third coating slurry includes the following steps:

[0178] The antistatic agent, softener and deionized water were mixed in a mass ratio of 1:1:99.2, and stirred at 48° C. for 70 minutes to obtain the third coating slurry;

[0179] The antistatic agent includes octadecyl dihydroxyethyl betaine;

[0180] The softener includes sodium sulfosuccinate.

[0181] The fiber bundle wire feeding speed is 0.16 m / min, and the lengths of the first drying conveyor belt, the second drying conveyor belt and the third drying conveyor belt are all 8 m.

[0182] The first drying, the second drying and the third drying are all performed at 70°C.

[0183] Another aspect of the present invention provides a bundled mullite fiber with a surface coating attached thereto.

[0184] The mass of the surface coating of the bundled mullite fibers with attached surface coating is 0.9% of the total mass of the bundled mullite fibers;

[0185] The average tensile strength of the mullite fiber before sizing is 1.95 GPa; the average tensile strength of the bundled mullite fiber with surface coating is 2.06 GPa; the organic components in the surface coating are removed at 320°C before use.

[0186] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features have similar functions to those disclosed in the present application (but not limited to).

Claims

1. A method for preparing a mullite fiber surface coating, characterized in that: The following steps are involved: preparing a first coating slurry, wherein the first coating slurry includes mullite sol; preparing a second coating slurry, wherein the second coating slurry comprises a high molecular polymer and silica sol; preparing a third coating slurry, wherein the third coating slurry comprises an antistatic agent and a softener; The fiber bundle is sequentially and continuously immersed in the first coating slurry, the second coating slurry, and the third coating slurry in sequence, and the surface coating is attached to the surface of the fiber bundle; The fiber bundle is impregnated with a first coating slurry and dried for the first time, then impregnated with a second coating slurry and dried for the second time, and then impregnated with a third coating slurry and dried for the third time to obtain a bundled mullite fiber and a surface coating attached to the surface of the mullite fiber; The first drying, the second drying and the third drying temperatures are all 60-100°C.

2. The method for preparing a mullite fiber surface coating according to claim 1, characterized in that: The first coating slurry preparation method comprises the following steps: preparing a mullite sol; Add silane coupling agent to mullite sol, mix at 25-45°C, stir at 45-80°C for 0.5-3h to obtain first coating slurry; the amount of silane coupling agent added is 0.5-3% of the mass fraction of mullite sol. The solid content of the first coating slurry is 10-15%; The sol particle size in the first coating slurry is 50-200 nm. The silane coupling agent includes: one of an amino silane coupling agent and a vinyl silane coupling agent.

3. The method for preparing the surface coating of mullite fiber according to claim 2, characterized in that: The mullite sol preparation process comprises the following steps: Modifying a silica sol having a solid content of 10-15% by means of a carboxylic acid, adjusting the pH to 2-3, and stirring at 30-50° C. for 3-5 hours to obtain a modified silica sol; The modified silica sol and 10-15% acidic aluminum sol are mixed in a mass ratio of 1:(2.5-4.5), and stirred at 40-80° C. for 5-10 hours to prepare a mullite sol.

4. The method for preparing a mullite fiber surface coating according to claim 1, characterized in that: The second coating slurry preparation method comprises the following steps: Mixing a high molecular polymer with deionized water, with a mass fraction of the high molecular polymer being 0.5-3%, stirring at 70-90° C. for 60-120 minutes, and then cooling the temperature to room temperature to obtain a high molecular polymer solution; The prepared high molecular polymer solution is mixed with ethanol and silica sol, the mass ratio of the high molecular polymer solution to ethanol is 1: (0.5-1.5), and the mass ratio of the high molecular polymer solution to silica sol with a solid content of 10-15% is 1: (0.1-0.3), and then stirred at 35-55° C. for 30-60 minutes to obtain a polymer silica sol mixed solution; Add an emulsifier to the polymer silica sol mixed solution, stir at 45-55° C. for 60-120 minutes to obtain a second coating slurry; The emulsifier accounts for 0.1-1% by mass of the polymer silica sol mixed solution; The emulsifier includes one or more of sodium dodecyl sulfonate, sodium dodecylbenzene sulfonate, and sodium dodecyl sulfonate.

5. The method for preparing the surface coating of mullite fiber according to claim 4, characterized in that: The solid content of the second coating slurry is 0.5-5.0%; The particle size of the sol in the second coating slurry is 10-30 nm.

6. The method for preparing a mullite fiber surface coating according to claim 1, characterized in that: The third coating slurry preparation method comprises the following steps: The antistatic agent, the softener and the deionized water are mixed in a mass ratio of 1:1:(99.0-99.9), and stirred at 45-55° C. for 60-120 minutes to obtain the third coating slurry; The antistatic agent includes one or more of lauryl alcohol polyoxyethylene ether phosphate potassium salt, hexadecanol sulfate methyl salt, and octadecyl dihydroxyethyl betaine; The softener includes one or more of sodium lauryl sulfate, sodium fatty alcohol polyoxyethylene ether sulfate, and sodium sulfosuccinate.

7. The method for preparing the surface coating of mullite fiber according to claim 2, characterized in that: The second coating slurry also includes paraffin wax; The polymer and deionized water are mixed in a mass ratio, stirred at 70-90° C. for 60-120 minutes, and then paraffin is added, and the stirring is continued for 10-30 minutes to obtain a polymer solution, which is maintained at 50-70° C. for standby use; the mass ratio of the polymer, paraffin and deionized water is 1:(0.3-1.2):(0.5-1.5); The prepared high molecular polymer solution is mixed with ethanol and silica sol at 55-65°C, the mass ratio of the high molecular polymer solution to ethanol is 1:(0.5-1.5), and the mass ratio of the high molecular polymer solution to silica sol with a solid content of 10-15% is 1:(0.1-0.3), and then stirred at 55-65°C for 30-60 minutes to obtain a polymer silica sol mixed solution; An emulsifier is added to the polymer silica sol mixed solution, and stirred at 55-65° C. for 60-120 minutes to obtain a second coating slurry; the emulsifier accounts for 0.1-1% of the mass fraction of the polymer silica sol mixed solution; and the mixture is maintained at 50-65° C. for standby use.

8. The method for preparing a mullite fiber surface coating according to claim 1, characterized in that: The process of attaching a surface coating to the fiber bundle includes the following steps: The fiber bundle is sequentially impregnated with a first coating slurry, a second coating slurry, and a third coating slurry through a continuous impregnation and drying device; The continuous impregnation and drying device comprises a first impregnation device, a first continuous drying device, a second impregnation device, a second continuous drying device, a third impregnation device, and a third continuous drying device; The first impregnation device continuously impregnates the surface of the fiber bundle with the first coating slurry and then performs the first drying through the first continuous drying device; the second impregnation device continuously impregnates the fiber bundle with the second coating slurry and then performs the second drying through the second continuous drying device; the third spraying slurry continuously sprays the fiber bundle with the third coating slurry and then performs the third drying; the bundled mullite fibers and the surface coating attached to the surface of the mullite fibers are obtained.

9. The method for preparing a mullite fiber surface coating according to claim 1, characterized in that: The first impregnation device comprises a first container, a first supporting roller A, a plurality of first supporting rollers B, a plurality of first pressing rollers A, a first pressing roller B, and a first supporting roller C; The first support roller A and the first support roller B are located below the fiber bundle, and the first pressing roller A and the first pressing roller B are located above the fiber bundle; the plurality of first support rollers B, the first pressing roller A, and the first pressing roller B are located between the first support roller A and the first support roller B; The first support roller A and the first support roller C are located above the highest point of the continuous fiber matrix impregnation device; The first support roller B and the first pressing roller A are located inside the dipping compound container, and part or all of the first support roller B and the first pressing roller A are located below the surface of the first coating slurry inside the first container; The first pressing roller B is located between the first pressing roller A and the first supporting roller C; The first pressing roller A and the first supporting roller B are arranged opposite to each other, and the fiber bundle passes between the first pressing roller A and the first supporting roller B; and / or The second impregnation device comprises a second container, a second pressing roller A, a second supporting roller A, a second supporting roller B, and n second supporting rollers C, where n≥4; a second coating slurry is arranged in the second container; the second supporting roller A is located outside the second container, higher than the second container, located above the second container, and located on the side of the second container close to the first impregnation device; the second supporting roller B is located outside the second container, higher than the second container, and located above one end of the second container close to the continuous drying device; the n second supporting rollers C are all located inside the second container, divided into two columns A and B, and the third supporting rollers in each column are arranged in sequence from top to bottom in the second container; the second supporting rollers C in column A are located on the side of the second container close to the connection and modification device, and the second supporting rollers C in column B are located on the side of the second container close to the connection and drying device, and the second pressing roller A is located inside the second container, inside the second container close to the drying device, and the height of the second pressing roller A is not higher than the lowest height of the second supporting rollers C in column B; and / or The third slurry spraying device includes a first lifting device, a spraying device A, a first spraying bracket, a spraying device B, a second spraying bracket, a spraying device C, a third spraying bracket, and a recovery container; The first lifting device includes a first lifting bracket, a first lifting pressure roller, a second lifting pressure roller, and a first lifting support roller at an angle of 60-90 degrees to the ground; The first lifting roller and the first lifting support roller are rotatably connected to the first lifting bracket, and the second lifting roller is rotatably connected to the first lifting bracket or the second recovery container; The first spray bracket is rotatably connected to the first spray support roller A and the first spray pressure roller B; The second spray bracket is rotatably connected to the second spray support roller A and the second spray pressure roller B; The third spray bracket is rotatably connected to the second spray support roller A and the second spray pressure roller B; The spray device A is arranged opposite to the first spray bracket, the spray device B is arranged opposite to the second spray bracket, and the spray device C is arranged opposite to the third spray bracket; and / or The first continuous drying device comprises a first drying roller A, a first drying roller B, a first box, and a first heat source and a first drying conveyor belt located inside the first box; The first drying roller A and the first drying roller B are located outside the first box; and / or The second continuous drying device comprises a second drying roller A, a second drying roller B, a second box, and a second heat source and a second drying conveyor belt located inside the second box; The second drying roller A and the second drying roller B are located outside the second box; and / or The third continuous drying device comprises a third drying roller A, a third drying roller B, a third box, and a third heat source and a third drying conveyor belt located inside the third box; The third drying roller A and the third drying roller B are located outside the third box. Preferably, the fiber bundle wire feeding speed is 0.1-0.5 m / min, and the lengths of the first drying conveyor belt, the second drying conveyor belt and the third drying conveyor belt are all 3-10 m.

10. The bundled mullite fiber with surface coating according to claim 1, characterized in that: The method for preparing a mullite fiber surface coating according to any one of claims 1 to 9 is used to prepare the mullite fiber surface coating; the mass of the surface coating of the bundled mullite fiber with the surface coating is 0.8-2% of the total mass of the bundled mullite fiber; The average tensile strength of the bundled mullite fibers of the surface coating is 2.0-2.2 GPa.

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