JP3945407B2 - Method for producing continuous fiber coated with inorganic material - Google Patents

Description

【００２５】
【発明の効果】
以上説明したように、本発明は、繊維束を構成する単繊維間の接着のない無機質材料被覆連続繊維の製造技術に関するものであり、連続繊維表面にコーティング液を塗布した後、繊維束をコーティング液に不溶な溶媒中で開繊することにより、繊維間にコーティング液に不溶な溶媒を繊維間に満たすことで、繊維束を構成する単繊維間の接着のない連続繊維を得ることができる。
【図面の簡単な説明】
【図１】図１は、本発明に用いる二層コーティング装置の一例を示す概略図である。
【図２】図２は、二層コーティングの概念を示す図である。
【図３】図３は、開繊用ノズルの液流先端の形状の一例を示す図である。
【図４】図４は、開繊用ノズルの液流先端の圧力分布の一例を示す図である。
【符号の説明】
１：送り出しボビン
２：繊維
３：デサイズ炉
４：コーティング浴
５：コーティング液
６：開繊用ノズル
７：循環ポンプ
８：開繊ローラー
９：開繊浴
１０：開繊用溶媒
１１：不融化炉
１２：開繊用溶媒乾燥炉
１３：無機化炉
１４：サイジング浴
１５：サイジング剤
１６：乾燥炉
１７：巻き取りボビン
２１：繊維
２２：第一層
２３：第二層
２４：第一層の無機化層
２５：接着を起こした部分[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing an inorganic material-coated continuous fiber having no adhesion between single fibers constituting a fiber bundle.
[0002]
[Prior art]
Since ceramic materials have heat resistance and oxidation resistance, they are expected to be used in fields such as the energy industry, aerospace, and nuclear power fields where usage environments are extremely severe. However, ceramics are problematic in that they are brittle and have low strength reliability based on the properties unique to the material. For this reason, fiber reinforced ceramics with improved toughness by compounding inorganic fibers in a ceramic matrix have been developed. Among these, in particular, SiC / SiC composite materials using silicon carbide fibers (hereinafter referred to as SiC fibers) as reinforcing fibers and silicon carbide as a matrix are expected to be used in the above fields due to their high heat resistance.
[0003]
In addition, in ceramic-based composite materials, much research has been conducted to improve the heat resistance of matrices and fibers, and in particular, the heat resistance of fibers that are reinforcing materials has been dramatically improved (for example, Patent Document 1). reference.).
[0004]
On the other hand, in the SiC / SiC composite material, by providing a layer that exhibits an appropriate sliding effect, such as carbon C and boron nitride BN, at the interface between the matrix and the fiber, it causes deflection of the developing crack, High toughness is imparted to ceramics that undergo brittle fracture.
These interface materials are usually deposited on the fiber surface by decomposing the raw material gas in a high-temperature inert gas atmosphere. In the case of carbon, it is deposited on the fiber surface by thermally decomposing a hydrocarbon gas typified by methane or propane at a high temperature. On the other hand, boron nitride reacts with a gas containing boron such as ammonia NH ₃ as a nitrogen source, boron trichloride BCl ₃ , boron trifluoride BF ₃ , diborane B ₂ H ₆ as a boron source at a high temperature of 1000 ° C. or more. Thus, hexagonal boron nitride (h-BN) having a layered structure is obtained.
[0005]
An oxide interface material is also used as an interface material of a composite material, and an oxide-based composite material using β-alumina containing potassium or calcium at the interface has been developed (for example, see Patent Document 2). .).
[0006]
On the other hand, as a method for forming the above-mentioned interface material, in the case of a carbon or h-BN interface layer, a vapor phase chemical deposition method (CVD method) is most commonly used. These methods are excellent as a method for forming a uniform interface layer on the surface of each fiber constituting the fiber bundle. However, this is an industrially disadvantageous method because the gas used as a raw material is expensive, the apparatus is expensive because a vacuum vessel is used, and the coating speed is relatively slow.
[0007]
As a method for forming the oxide interface layer, a technique of coating in a liquid phase using a metal alkoxide or the like as a raw material is used. According to this technique, an oxide interface layer is formed at low cost without using a vacuum vessel or the like. However, when the interface layer is formed in the liquid phase, there has been a problem that the single fibers forming the fiber bundle are bonded to each other through the interface layer. Therefore, a method for eliminating the adhesion between fibers has been proposed (see, for example, Patent Document 3).
When the fiber is coated with the solution by the above method, once the fiber bundle is immersed in the coating liquid, the larger the surface energy between the coating liquid and the fiber surface, the more the fibers are focused. It was very difficult to separate the single fibers in this concentrated state, and it was difficult to obtain continuous fibers in which the single fibers were not bonded by the coating layer.
[0008]
[Patent Document 1]
JP-A-11-36142 [Patent Document 2]
JP-A-6-92744 [Patent Document 3]
US Pat. No. 5,164,229
[Problems to be solved by the invention]
In order to solve the above-described problems, an object of the present invention is to provide a technique for forming a coating layer in which there is no adhesion between single fibers constituting a fiber bundle.
[0010]
[Means for Solving the Problems]
The present invention
(1) A step of applying a coating liquid (first layer) for forming a coating layer made of an inorganic material on the continuous fiber surface;
(2) The fiber bundle of the continuous fiber coated with the first layer is opened in a solvent insoluble in the coating solution to cover the surface of the single fiber constituting the fiber bundle with the first layer, and the single fiber Coating with a solvent (second layer) insoluble in the coating liquid between,
(3) making the first layer infusible;
(4) a step of evaporating and drying the second layer;
(5) The present invention relates to a method for producing an inorganic material-coated continuous fiber in which the single fibers constituting the fiber bundle are not bonded, comprising the step of mineralizing the infusible first layer.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
An example of the coating apparatus used in the present invention is shown in FIG.
3 is a coating bath for coating the coating liquid 5 on the continuous fiber 2. 9 is a fiber-spreading bath that opens a fiber bundle coated with a coating solution. 6 is a nozzle for opening the fiber bundle, and 7 is a circulation pump for circulating the solvent 10 for opening. No. 6 opening nozzle has an orifice that generates a liquid flow having an optimum shape and linear velocity for opening. 11 is a furnace for making the coating liquid infusible. Reference numeral 12 denotes a drying furnace for drying the solvent 10. 13 is an inorganic furnace for mineralizing the coating layer infusible in the infusibilizing furnace 11 to remove organic components.
As shown in FIG. 2A, the fibers 2 that have passed through the coating bath are in a state where the fibers are converged by the surface tension of the coating liquid 2. If the infusibilization / mineralization process is passed in this state, the fibers are bonded by the coating layer as shown in FIG. By passing the fiber passed through the coating bath through the opening bath, as shown in FIG. 2 (c), a solvent insoluble in the coating solution can be filled between the fibers as shown in FIG. As shown in d), continuous fibers with no adhesion between the fibers are obtained.
[0012]
As a coating solution, a sol-gel solution using an alcohol solvent in which a metal alkoxide is dissolved, or a solution in which a higher alcohol such as ethylene glycol, diethylene glycol or triethylene glycol and an organic acid such as acetic acid, butyric acid, lactic acid or citric acid are dissolved. In addition, by dissolving salts containing metals such as chlorides, nitrates, sulfates, oxychlorides, etc. soluble in these higher alcohols, and polymerizing alcohol and organic acid as a solvent by esterification reaction, metal elements A polymer solution that uniformly contains a complex polymer or an organosilicon polymer precursor diluted with an organic solvent such as xylene or toluene can be considered, but for the purpose of forming a coating layer on the fiber surface, the type of solution can be selected. It is not limited.
[0013]
The solvent used in the opening bath is an organic solvent that is insoluble in the coating liquid described above, and it is necessary that there is no residue after drying and removal. In some cases, it is necessary to have a boiling point higher than the infusibilization temperature of the coating liquid.
For example, when a complex polymer is used for the coating solution, it requires infusibilization, so dodecane (CH ₃ (CH ₂ ) ₁₀ CH ₃ ), tridecane (CH ₃ (CH ₂ ) ₁₁ CH ₃ ), tetradecane ( High boiling point hydrocarbons such as CH ₃ (CH ₂ ) ₁₂ CH ₃ ) can be used. In the case of a sol-gel solution, the boiling point is higher than the hydrolysis temperature, although it is not as high as the complex polymer. Therefore, hexane (CH ₃ (CH ₂ ) ₄ CH ₃ ), heptane (CH ₃ (CH ₂ ) ₅ CH ₃ ), perfluorohexane (C ₆ F ₁₄ ), dichlorohexane (Cl (CH ₂ ) Cl), dodecane (CH ₃ (CH ₂ ) ₁₀ CH ₃ ), tridecane (CH ₃ (CH ₂ ) ₁₁ CH ₃ ) Tetradecane (CH ₃ (CH ₂ ) ₁₂ CH ₃ ) or the like can be used.
The liquid flow for opening greatly affects the opening property. Since the liquid flow is sprayed onto the fiber bundle with a liquid flow of a predetermined shape, the desired continuous coated fiber can be obtained by appropriately controlling the shape of the liquid flow, its spreading angle, and the linear velocity at the tip of the opening nozzle.
Any spray angle can be used as long as the spray angle of the opening nozzle is 150 ° or less to 10 ° or more. The linear velocity at the tip of the opening nozzle is desirably 200 m / second or less. The shape of the liquid flow tip is not particularly limited, and any shape can be used as long as it is a circle, a rectangle having an aspect ratio of 1 or more and 1000 or less, or an ellipse having a major axis / minor axis ratio of 1 or more and 1000 or less. For example, as shown in FIG. 3, a circle, a square, a rectangle, an ellipse, and the like are conceivable. As the pressure distribution, as shown in FIG. 4, there can be used one having a uniform surface as a whole, or a pressure distribution which becomes lower as the central portion becomes higher and becomes a peripheral portion, but the pressure distribution is not particularly limited. The linear velocity at the tip of the opening nozzle can also be selected over a wide range depending on the type of coating liquid and opening solvent.
[0014]
In order to coat a double liquid layer on the fiber surface, surface tension is important. The degree of wettability of the liquid to the solid can be indicated by the contact angle. Assuming that the surface tension between the coating liquid and the fiber, between the coating liquid and the insoluble solvent, and between the fiber and the insoluble solvent is γ _CF , γ _CI , and γ _IF , respectively, the droplets are stabilized on the fiber surface. The relationship holds.
γ _IF = γ _CI cos θ + γ _CF (θ: contact angle)
θ is a measure of the wettability of the fiber surface to the solution. For example, between γ _CF , γ _CI , and γ _IF , a solution having a strong interaction with the fiber surface that can be expressed by the relationship of formula (1), that is, a solution having a larger γ _IF than the sum of γ _CI and γ _CF Is combined, the coating liquid spreads on the fiber surface, and as a result, θ in the above formula approaches 0.
γ _IF > γ _CI + γ _CF (1)
[0015]
From the above, when a coating solution having a larger γ _IF than the sum of γ _CI and γ _CF , which can be expressed by the relationship of equation (1), is selected, the coating solution preferentially covers the fiber surface. . However, when the coating liquid covers the fiber surface, the surface tension between the coating liquid and the insoluble solvent is large, so that the space between the fibers is filled with the coating liquid. If it mineralizes in this state, between fibers will adhere in an interface layer. In order to fill the insoluble solution between the fibers filled with the coating solution, it is necessary to open the fiber bundle.
In the method of the present invention, a fiber coated with a coating solution is passed between a fixed roller and a liquid flow of an insoluble solvent, so that a coating solution and a solvent insoluble in the coating solution are removed while the fiber bundle is opened. A continuous fiber coated in layers is obtained. If the relationship of the formula (1) is established among γ _CF , γ _CI , and γ _IF , the coating liquid is not removed from the fiber surface by fiber opening. Thereby, the continuous fiber without adhesion between fibers after mineralization can be obtained.
[0016]
【Example】
Example 1
Dissolve 0.23 g of calcium metal (Ca), 28.14 g of aluminum isopropoxide (Al (O.C ₃ H ₇ ) ₃ ), 2.33 g of water, 124.11 g of acetic acid, and 1.68 g of acetylacetone in 2-propanol. 300 g of a sol-gel solution for coating was prepared.
The prepared sol-gel solution is filled in the coating bath 4 shown in FIG. The opening bath 9 is filled with hexane as a solvent insoluble in the sol-gel solution. The silicon carbide fiber was passed through a desize furnace 3 for removing impurities on the fiber surface from the delivery bobbin 1. The desize furnace temperature was 500 ° C. The resized fiber is guided to each step through a pulley. The coating solution was applied in the coating bath 4 and then opened in the opening solvent 9 with the opening solvent 10. The liquid flow tip shape of the opening nozzle was elliptical, and the pressure distribution at the nozzle tip was uniform over the entire surface. The jet angle of the liquid flow was 90 °, and the distance between the fiber bundle to be opened and the nozzle tip was 10 mm. Subsequently, the sol-gel solution was hydrolyzed and infusible at 110 ° C. in the infusibilizing furnace 11. After removing hexane, which is a solvent for opening, in a solvent drying furnace for opening, it was mineralized at 550 ° C. in an inorganicizing furnace 13. The obtained fiber was a continuous fiber with no coating between the fibers as shown in FIG. 2 (d).
[0017]
Example 2
37.36 g of aluminum nitrate nonahydrate (Al (NO ₃ ) ₃ · 9H ₂ O), calcium chloride (CaCl ₂ ), and 159.47 g of citric acid were dissolved in 206.07 g of ethylene glycol (HOCH ₂ CH ₂ OH). 300 g of a complex polymer solution for coating was prepared.
The prepared complex polymer liquid is filled in the coating bath 4 shown in FIG. The opening bath 9 is filled with tetradecane as a solvent insoluble in the complex polymer solution. The silicon carbide fiber was passed through a desize furnace 3 for removing impurities on the fiber surface from the delivery bobbin 1. The desize furnace temperature was 500 ° C. The resized fiber is guided to each step through a pulley. The coating solution was applied in the coating bath 4 and then opened in the opening solvent 9 with the opening solvent 10. The liquid flow tip shape of the opening nozzle was elliptical, and the pressure distribution at the nozzle tip was uniform over the entire surface. The jet angle of the liquid flow was 90 °, and the distance between the fiber bundle to be opened and the nozzle tip was 10 mm. Subsequently, the coating solution was infusibilized at 200 ° C. in the infusibilization furnace 11. After removing tetradecane, which is a solvent for opening, in a solvent drying oven for opening, it was mineralized at 550 ° C. in an inorganicizing furnace 13. The obtained fiber was a continuous fiber with no coating between the fibers as shown in FIG. 2 (d).
[0018]
Example 3
In the same manner as in Example 1, 300 g of a sol-gel solution for coating was prepared. The prepared sol-gel solution is filled in the coating bath 4 shown in FIG. The opening bath 9 is filled with hexane as a solvent insoluble in the sol-gel solution. The silicon carbide fiber was passed through a desize furnace 3 for removing impurities on the fiber surface from the delivery bobbin 1. The desize furnace temperature was 500 ° C. The resized fiber is guided to each step through a pulley. The coating solution was applied in the coating bath 4 and then opened in the opening solvent 9 with the opening solvent 10. The liquid flow tip shape of the opening nozzle was square, and the pressure distribution at the nozzle tip was made uniform over the entire surface. The jet angle of the liquid flow was 90 °, and the distance between the fiber bundle to be opened and the nozzle tip was 10 mm. Subsequently, the sol-gel solution was hydrolyzed and infusible at 110 ° C. in the infusibilizing furnace 11. After removing hexane, which is a solvent for opening, in a solvent drying furnace for opening, it was mineralized at 550 ° C. in an inorganicizing furnace 13. The obtained fiber was a continuous fiber with no coating between the fibers as shown in FIG. 2 (d).
[0019]
Example 4
In the same manner as in Example 2, 300 g of the complex polymer solution for coating was prepared. The prepared complex polymer liquid is filled in the coating bath 4 shown in FIG. The opening bath 9 is filled with tetradecane as a solvent insoluble in the complex polymer solution. The silicon carbide fiber was passed through a desize furnace 3 for removing impurities on the fiber surface from the delivery bobbin 1. The desize furnace temperature was 500 ° C. The resized fiber is guided to each step through a pulley. The coating solution was applied in the coating bath 4 and then opened in the opening solvent 9 with the opening solvent 10. The liquid flow tip shape of the opening nozzle was square, and the pressure distribution at the nozzle tip was made uniform over the entire surface. The jet angle of the liquid flow was 90 °, and the distance between the fiber bundle to be opened and the nozzle tip was 10 mm. Subsequently, the coating solution was infusibilized at 200 ° C. in the infusibilization furnace 11. After removing tetradecane, which is a solvent for opening, in a solvent drying oven for opening, it was mineralized at 550 ° C. in an inorganicizing furnace 13. The obtained fiber was a continuous fiber with no coating between the fibers as shown in FIG. 2 (d).
[0020]
Comparative Example 1
In the same manner as in Example 1, 300 g of a sol-gel solution for coating was prepared. The prepared sol-gel solution is filled in the coating bath 4 shown in FIG. The opening bath 9 is filled with hexane as a solvent insoluble in the sol-gel solution. The silicon carbide fiber was passed through a desize furnace 3 for removing impurities on the fiber surface from the delivery bobbin 1. The desize furnace temperature was 500 ° C. The resized fiber was led to each step via a pulley. The coating solution was applied in the coating bath 4, and the sol-gel solution was hydrolyzed and infusibilized in the infusibilizing furnace 11 at 110 ° C. without passing through the opening bath. The mineralization furnace 13 mineralized at 550 ° C. The obtained fiber was a continuous fiber in which the fibers were bonded with a coating layer as shown in FIG.
[0021]
Comparative Example 2
In the same manner as in Example 2, 300 g of the complex polymer solution for coating was prepared. The prepared complex polymer liquid is filled in the coating bath 4 shown in FIG. The opening bath 9 is filled with tetradecane as a solvent insoluble in the complex polymer solution. The silicon carbide fiber was passed through a desize furnace 3 for removing impurities on the fiber surface from the delivery bobbin 1. The desize furnace temperature was 500 ° C. The resized fiber is guided to each step through a pulley. The coating liquid was applied in the coating bath 4, and the coating liquid was infusible at 200 ° C. in the infusibilizing furnace 11 without passing through the opening bath. The mineralization furnace 13 mineralized at 550 ° C. The obtained fiber was a continuous fiber in which the fibers were bonded with a coating layer as shown in FIG.
[0022]
Comparative Example 3
In the same manner as in Example 1, 300 g of a sol-gel solution for coating was prepared. The prepared sol-gel solution is filled in the coating bath 4 shown in FIG. The opening bath 9 is filled with hexane as a solvent insoluble in the sol-gel solution. The silicon carbide fiber was passed through a desize furnace 3 for removing impurities on the fiber surface from the delivery bobbin 1. The desize furnace temperature was 500 ° C. The resized fiber is guided to each step through a pulley. The coating solution was applied in the coating bath 4, and then the opening solvent 9 was coated in the opening bath 9, and the opening with the opening nozzle was not performed. The sol-gel solution was hydrolyzed and infusible at 110 ° C. in the infusibilizing furnace 11. After removing hexane, which is a solvent for opening, in a solvent drying furnace for opening, it was mineralized at 550 ° C. in an inorganicizing furnace 13. The obtained fiber was a continuous fiber in which the fibers were bonded with a coating layer as shown in FIG.
[0023]
Comparative Example 4
In the same manner as in Example 2, 300 g of the complex polymer solution for coating was prepared. The prepared complex polymer liquid is filled in the coating bath 4 shown in FIG. The opening bath 9 is filled with tetradecane as a solvent insoluble in the complex polymer solution. The silicon carbide fiber was passed through a desize furnace 3 for removing impurities on the fiber surface from the delivery bobbin 1. The desize furnace temperature was 500 ° C. The resized fiber is guided to each step through a pulley. The coating solution was applied in the coating bath 4, the solvent 10 for opening was subsequently coated in the opening bath 9, and the opening with the opening nozzle was not performed. The coating solution was infusible at 200 ° C. in the infusibilizing furnace 11. After removing tetradecane which is a solvent for opening in a solvent drying furnace for opening, it was mineralized in a mineralizing furnace 13 at 550 ° C. The obtained fiber was a continuous fiber in which the fibers were bonded with a coating layer as shown in FIG.
The results of the above examples and comparative examples are summarized in Table 1.
[0024]
[Table 1]

[0025]
【The invention's effect】
As described above, the present invention relates to a technique for producing an inorganic material-coated continuous fiber having no adhesion between single fibers constituting the fiber bundle, and coating the fiber bundle after applying the coating liquid on the surface of the continuous fiber. By performing fiber opening in a solvent insoluble in the liquid, a fiber insoluble in the coating liquid between the fibers is filled between the fibers, so that continuous fibers without adhesion between single fibers constituting the fiber bundle can be obtained.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an example of a two-layer coating apparatus used in the present invention.
FIG. 2 is a diagram showing the concept of two-layer coating.
FIG. 3 is a diagram illustrating an example of a shape of a liquid flow front end of the opening nozzle.
FIG. 4 is a diagram illustrating an example of a pressure distribution at a liquid flow tip of a fiber-spreading nozzle.
[Explanation of symbols]
1: Sending bobbin 2: Fiber 3: Desizing furnace 4: Coating bath 5: Coating liquid 6: Opening nozzle 7: Circulation pump 8: Opening roller 9: Opening bath 10: Opening solvent 11: Infusible furnace 12: Solvent drying furnace 13: Mineralization furnace 14: Sizing bath 15: Sizing agent 16: Drying furnace 17: Winding bobbin 21: Fiber 22: First layer 23: Second layer 24: First layer inorganic Layer 25: the part where adhesion occurred

Claims (10)

(1) A step of applying a coating liquid (first layer) for forming a coating layer made of an inorganic material on the continuous fiber surface;
(2) The fiber bundle of the continuous fiber coated with the first layer is opened in a solvent insoluble in the coating solution to cover the surface of the single fiber constituting the fiber bundle with the first layer, and the single fiber Coating with a solvent (second layer) insoluble in the coating liquid between,
(3) making the first layer infusible;
(4) a step of evaporating and drying the second layer;
(5) A method for producing a continuous fiber coated with an inorganic material in which the single fibers constituting the fiber bundle are not bonded, the method comprising the step of mineralizing the infusible first layer. With respect to the surface tension between the coating liquid according to claim 1, the solvent insoluble in the coating liquid (second layer) and the fiber surface, between the coating liquid and the fiber, the coating liquid and the second layer, and the fiber and the second layer. 2. The first layer, the second layer, and the fiber that satisfy the relationship of the formula (1) are used between the surface tensions of γ _CF , γ _CI , and γ _IF , respectively. The manufacturing method of the inorganic material covering continuous fiber as described in 1 ..
γ _IF > γ _CI + γ _CF (1) In the step of coating the second layer according to claim 1, the second layer is fed with a circulation pump, sprayed from the opening nozzle, and sprayed onto the fiber bundle passing over the opening roller to open the fiber bundle. The method for producing a continuous fiber coated with an inorganic material according to claim 1, wherein the second layer is coated while fibering. The method for producing a continuous fiber coated with an inorganic material according to claim 3, wherein the spray angle of the nozzle for opening fiber according to claim 3 is 150 ° or less and 10 ° or more. The shape of the liquid flow tip of the opening nozzle according to claim 3 is circular, a rectangle having an aspect ratio of 1 or more and 1000 or less, or an ellipse having a major axis / minor axis ratio of 1 or more and 1000 or less. The manufacturing method of the inorganic material covering continuous fiber of Claim 3. The method for producing an inorganic material-coated continuous fiber according to claim 3, wherein the linear velocity at the tip of the opening nozzle according to claim 3 is 100 m / sec or less. 4. The method for producing an inorganic material-coated continuous fiber according to claim 3, wherein the pressure distribution at the tip of the opening nozzle according to claim 3 is higher at the central portion and lower at the peripheral portion. The method for producing a continuous fiber coated with an inorganic material according to claim 3, wherein the pressure distribution at the tip of the opening nozzle according to claim 3 is uniform over the entire surface. 2. The inorganic material-coated continuous fiber according to claim 1, wherein the second layer according to claim 1 is a high-boiling hydrocarbon compound having a boiling point higher than the infusibilizing temperature of the coating liquid (first layer). Manufacturing method. The fiber according to claim 1 is at least one selected from carbon fiber, graphite fiber, silica fiber, silicon carbide fiber, silicon nitride fiber, boron fiber, alumina fiber, mullite fiber, and yttria-alumina fiber. 2. A process for producing an inorganic material-coated continuous fiber according to 1.

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