JP2009274890A - Method for curing coating of optical fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for curing a coating of a wire material, by which the production cost can be reduced by reducing the consumption of an inert gas in an ultraviolet ray irradiation furnace, and at the same time, the miniaturization of an apparatus and the reduction of apparatus cost can be achieved by downsizing inert gas supply equipment. <P>SOLUTION: The method for curing a coating of an optical fiber comprises curing an ultraviolet ray-curable resin 4 for coloring applied on the outer periphery of the optical fiber 3 by a plurality of stages of ultraviolet ray irradiation furnaces 11, 14, 16. The ultraviolet ray irradiation furnaces 11 is provided in the initial stage after the ultraviolet ray-curable resin 4 for coloring is applied on the optical fiber 3 and irradiates the ultraviolet ray-curable resin 4 applied on the fiber 3 with an ultraviolet ray under such a condition that the periphery of the optical fiber 3 is purged by an inert gas. The plurality of ultraviolet ray irradiation furnaces 14, 16 except the ultraviolet ray irradiation furnaces 11 provided in the initial stage after the ultraviolet ray-curable resin 4 for coloring is applied, irradiate the ultraviolet ray-curable resin 4 applied on the fiber 3 with an ultraviolet ray without purging the periphery of the optical fiber 3 with an inert gas. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for coating and curing an optical fiber in which an ultraviolet curable resin applied to an optical fiber is cured by ultraviolet irradiation to form an optical fiber whose outer periphery is covered with a resin coating.

  As a method for coloring the outer periphery of an optical fiber, a method is known in which an ultraviolet curable resin of a predetermined color applied to the optical fiber is cured by ultraviolet irradiation to obtain an optical fiber whose outer periphery is colored in a predetermined color. It has been.

Specifically, such a coloring method is performed by the following procedure.
First, an optical fiber strand is inserted into a coloring die storing an ultraviolet curable resin liquid (ultraviolet curable ink) of a predetermined color, and an outer periphery of the optical fiber strand is coated with an ultraviolet curable resin.
Next, an optical fiber strand having an ultraviolet curable resin coating on the outer periphery is sequentially passed through an ultraviolet irradiation furnace arranged in a plurality of stages, and the ultraviolet curable resin coating is cured by ultraviolet irradiation in each ultraviolet irradiation furnace. . The reason why a plurality of ultraviolet irradiation furnaces are used is that when the coloring line speed is increased, a sufficient ultraviolet irradiation amount cannot be obtained with only one ultraviolet irradiation furnace.

By the way, in the ultraviolet curable resin, when there is oxygen at the time of curing by ultraviolet irradiation, the curing polymerization reaction is inhibited, thereby causing oxygen inhibition resulting in poor curing, and defects such as peeling of the coating easily occur.
Therefore, conventionally, all of the one-stage or plural-stage ultraviolet irradiation furnaces for irradiating ultraviolet curable resin applied to the bare optical fiber or the like with an N ₂ gas or the like inside (around the wire to be inserted) It was set as the structure which performs ultraviolet irradiation in the state purged with the active gas (for example, refer patent document 1 and patent document 2).

JP-A-5-213636 JP-A-62-158143

However, in general, in an optical fiber coloring processing apparatus or the like, for example, an ultraviolet irradiation furnace is provided in multiple stages such as six stages in order to cure the ultraviolet curable resin applied to the optical fiber. In the configuration in which the ultraviolet irradiation furnace is similarly purged with an inert gas, the amount of the inert gas used becomes enormous, resulting in an increase in the consumption of the inert gas, resulting in an increase in manufacturing cost.
In addition, a gas supply facility for supplying an inert gas to each ultraviolet irradiation furnace has to be provided, which causes a problem of increasing the size of the apparatus and increasing the cost of the apparatus.

  An object of the present invention is to obtain an optical fiber having a quality equal to or higher than that when purging all ultraviolet irradiation furnaces with an inert gas when coloring optical fiber strands, and to remove the inert gas in the ultraviolet irradiation furnace. An object of the present invention is to provide a method for coating and curing an optical fiber, which can reduce the manufacturing cost by reducing the consumption amount and at the same time reduce the size of the apparatus and reduce the cost of the apparatus by reducing the inert gas supply facility. .

(1) In order to solve the above-described problems, the optical fiber coating and curing method according to the present invention cures the coloring ultraviolet curable resin applied to the outer periphery of the optical fiber strand by a plurality of stages of ultraviolet irradiation furnaces. An optical fiber coating curing method comprising:
Among the ultraviolet irradiation furnaces provided in a plurality of stages, one or a plurality of ultraviolet irradiation furnaces including an ultraviolet irradiation furnace located in the first stage after the application of the coloring ultraviolet curable resin is applied to the optical fiber. With the surroundings purged with an inert gas, the colored ultraviolet curable resin applied to the optical fiber is irradiated with ultraviolet rays,
In addition, at least one of the one or a plurality of ultraviolet irradiation furnaces not including the ultraviolet irradiation furnace located in the first stage after the application of the coloring ultraviolet curable resin is an inert gas around the optical fiber. The ultraviolet curable resin for coloring applied to the optical fiber is irradiated with ultraviolet rays without purging in step (1).

(2) Further, the coating and curing method for an optical fiber according to (1) described above is an ultraviolet ray positioned in the first stage after the application of the coloring ultraviolet curable resin in the ultraviolet irradiation furnace equipped in the plurality of stages. Only the irradiation furnace is in a state where the periphery of the optical fiber is purged with an inert gas, and the ultraviolet curable resin for coloring applied to the optical fiber is irradiated with ultraviolet rays,
In addition, all the ultraviolet irradiation furnaces that do not include the ultraviolet irradiation furnace located in the first stage after the application of the coloring ultraviolet curable resin are used without purging the periphery of the optical fiber strand with an inert gas. It is preferable to irradiate the coloring ultraviolet curable resin applied to the fiber strand with ultraviolet rays.

In the optical fiber coating and curing method according to the present invention, purging with an inert gas in an ultraviolet irradiation furnace for the purpose of preventing curing failure due to oxygen inhibition during curing of an ultraviolet curable resin is performed in all ultraviolet irradiation furnaces. However, it is not implemented in some or all of the plurality of ultraviolet irradiation furnaces that do not include the ultraviolet irradiation furnace located in the first stage after the application of the coloring ultraviolet curable resin.
Therefore, compared to the conventional method in which purging with an inert gas is performed for all ultraviolet irradiation furnaces, the amount of inert gas used can be reduced, and the consumption of the inert gas in the ultraviolet irradiation furnace can be reduced. Reduction of manufacturing cost can be realized.

  Further, in an ultraviolet irradiation furnace that does not perform purging with an inert gas, an inert gas supply facility can be omitted, and compared with a conventional apparatus in which an inert gas supply facility is provided in all ultraviolet irradiation furnaces, an inert gas is provided. By reducing the supply facilities, it is possible to reduce the size of the apparatus and the apparatus cost.

  In addition, during the curing process by ultraviolet irradiation in an ultraviolet irradiation furnace that does not perform purging with an inert gas, the curing process is already performed in the ultraviolet irradiation furnace in which the surface of the ultraviolet curable resin applied to the optical fiber is positioned in the first stage. Since the cured surface functions as a blocking wall that blocks the inside of the UV curable resin from the outside air, oxygen inhibition is not required in the UV irradiation furnace after the first stage without purging with an inert gas. Therefore, it is possible to realize good coating formation with an ultraviolet curable resin. In particular, when a thin colored layer is formed, the curing reaction also starts inside the UV curable resin by the UV irradiation furnace located in the first stage, and purging with an inert gas is not performed in the UV irradiation furnaces after the first stage. Curing proceeds sufficiently. Accordingly, it is possible to obtain an optical fiber having a quality equal to or higher than that when purging all the ultraviolet irradiation furnaces with the inert gas.

  As described above, the method for coating and curing an optical fiber according to the present invention is a method in which a coloring ultraviolet curable resin applied to an optical fiber is cured by ultraviolet irradiation, and a predetermined color ultraviolet curable resin is applied. By doing so, it can be used for coloring an optical fiber. In addition, the present invention can be used for forming a resin coating on various metallic or non-metallic wires.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of an optical fiber coating and curing method according to the invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic configuration diagram of an embodiment of a coloring machine for carrying out a coating curing method for an optical fiber according to the present invention.

  A coloring machine 1 shown in FIG. 1 performs coloring of a predetermined color on the outer periphery of an optical fiber 3, a coloring die 5 for applying an ultraviolet curable resin 4 for coloring of a predetermined color on the outer periphery of the optical fiber 3, It is composed of a plurality of stages of ultraviolet irradiation furnaces 11, 14, 16 for curing the coloring ultraviolet curable resin 4 applied to the fiber 3 by ultraviolet irradiation. The coloring machine 1 uses a plurality of stages of ultraviolet irradiation furnaces in order to obtain a sufficient amount of ultraviolet irradiation even if the coloring line speed is increased. In addition, the optical fiber 3 is an optical fiber strand in which a coating layer of an ultraviolet curable resin is provided on the outer periphery of the glass fiber in the pre-process of the coloring process.

  The colored dice 5 are obtained by storing a predetermined color ultraviolet curable resin liquid (ultraviolet curable ink) 32 in a die body 31 into which the optical fiber 3 can be inserted, and have a predetermined thickness (on the outer periphery of the optical fiber 3 that passes therethrough. For example, a relatively thin UV curable resin 4 for coloring of 5 to 10 μm) is applied.

The ultraviolet irradiation furnace 11 located in the first stage after the application of the coloring ultraviolet curable resin 4 is disposed vertically below the coloring die 5.
The first-stage ultraviolet irradiation furnace 11 includes an ultraviolet irradiation means (lamp) that irradiates the coloring ultraviolet curable resin 4 applied to the optical fiber 3 that passes through the furnace case 21 through which the optical fiber 3 is inserted. ) Equipped with 25.

The two ultraviolet irradiation furnaces 14 and 16 are sequentially arranged below the first stage ultraviolet irradiation furnace 11.
Each of the ultraviolet irradiation furnaces 14 and 16 has the same basic structure as the ultraviolet irradiation furnace 11 in the first stage, and is colored with ultraviolet curing applied to the passing optical fiber 3 inside the furnace case 21 through which the optical fiber 3 is inserted. The mold resin 4 is provided with ultraviolet irradiation means 25 for irradiating the ultraviolet rays 23.

  Usually, when the ultraviolet curable resin 4 for coloring is irradiated with the ultraviolet rays 23, the curing starts in order from the surface side of the ultraviolet curable resin 4 for coloring to the inside, so that the ultraviolet irradiation furnace located immediately below the coloring die 5. 11 mainly plays a role for surface hardening, and two ultraviolet irradiation furnaces 14 and 16 arranged below the surface mainly play a role for internal hardening.

In the case of the present embodiment, the first stage ultraviolet irradiation furnace 11 is supplied with a quartz tube 22 surrounding the optical fiber 3 passing therethrough and a gas supply for supplying an inert gas such as N ₂ gas into the quartz tube 22. The facility 41 and a gas recovery facility 43 that exhausts and recovers the inert gas that has passed through the quartz tube 22 are connected. Arrows A and B in the figure indicate the flow direction of the inert gas.
The two ultraviolet irradiation furnaces 14 and 16 deployed for internal curing are not equipped with the gas supply equipment 41 and the gas recovery equipment 43, but may have a quartz tube 22 for maintenance.

In the coloring machine 1 having the above-described configuration, the optical fiber 3 coated with the coloring ultraviolet curable resin 4 on the outer periphery by the coloring die 5 is placed in three ultraviolet irradiation furnaces 11, 14, 16 arranged in a plurality of stages in the vertical direction. The optical fiber having the outer periphery colored by the coloring ultraviolet curable resin 4 is obtained by sequentially inserting and curing the coloring ultraviolet curable resin 4.
At that time, in the ultraviolet irradiation furnace 11 of the first stage, with the surroundings of the optical fiber 3 purged with an inert gas, the coloring ultraviolet curable resin 4 applied to the optical fiber 3 is irradiated with ultraviolet rays to cure the surface. In the two ultraviolet irradiation furnaces 14 and 16 for irradiating the finished ultraviolet curable resin 4 for ultraviolet irradiation with ultraviolet light, the surroundings of the optical fiber 3 are not purged with an inert gas in an ordinary air atmosphere. Perform UV irradiation.

  The coloring method carried out by the coloring machine 1 described above includes curing the colored ultraviolet curable resin 4 applied to the optical fiber 3 by ultraviolet irradiation, and then forming the optical fiber 3 whose outer periphery is covered with a colored layer of resin coating. What is formed is not limited to the optical fiber 3 but can be a metal or non-metal by appropriately selecting the components of the ultraviolet curable resin liquid 32 used for forming the ultraviolet curable resin 4 for coloring according to the application. It can be used as a general-purpose wire coating and curing method for forming a resin coating on various wire rods. Further, the present invention can be applied to a drawing process and a tape forming process of a wire such as an optical fiber.

Then, purging with an inert gas in the ultraviolet irradiation furnace for the purpose of preventing curing failure due to oxygen inhibition during curing of the ultraviolet curable resin is performed in the first ultraviolet irradiation furnace 11, but the first ultraviolet irradiation furnace 11. It is not carried out in the two ultraviolet irradiation furnaces 14 and 16 that do not contain.
Therefore, compared with the conventional method in which purging with an inert gas is performed for all ultraviolet irradiation furnaces, the amount of inert gas used can be reduced, and the consumption of the inert gas in the ultraviolet irradiation furnace can be reduced. A reduction in manufacturing cost when the optical fiber is colored can be realized.

  Further, in the ultraviolet irradiation furnaces 14 and 16 that do not perform purging with an inert gas, the quartz tube 22, the gas supply facility 41, and the gas recovery facility 43 that supply and discharge the inert gas around the optical fiber 3 can be omitted. Compared to the conventional equipment that provided inert gas supply equipment and gas recovery equipment in the ultraviolet irradiation furnace, the downsizing of the inert gas supply equipment, etc. can realize downsizing of the equipment and reduction of equipment cost. You can also.

  In addition, during the curing process by ultraviolet irradiation in the ultraviolet irradiation furnaces 14 and 16 that do not include the first stage ultraviolet irradiation furnace 11 among the plural stages of ultraviolet irradiation furnaces, the coloring ultraviolet curing type already applied to the optical fiber 3 is used. The surface of the resin 4 has been cured by the curing process in the ultraviolet irradiation furnace 11 in the first stage, and further, the curing of the inside of the ultraviolet curable resin 4 for coloring has started. For this reason, the cured surface functions as a blocking wall that shields the inside of the coloring ultraviolet curable resin 4 from the outside air. Therefore, the ultraviolet irradiation furnaces 14 and 16 do not perform purging with an inert gas, but are caused by oxygen inhibition. It is possible to realize good coating formation with an ultraviolet curable resin without causing poor curing.

Note that at least the purging with the inert gas is not effective, such as the reduction of the manufacturing cost by reducing the consumption of the inert gas, the downsizing of the apparatus by the reduction of the inert gas supply facility, etc. If there is only one UV irradiation furnace, it can be obtained accordingly.
Therefore, an ultraviolet irradiation furnace that performs ultraviolet irradiation without purging with an inert gas is not required for all the ultraviolet irradiation furnaces 14 and 16 that do not include the first stage ultraviolet irradiation furnace 11. However, the above-mentioned effect can be further improved by not performing purging with more furnaces among the plurality of ultraviolet irradiation furnaces.

  For example, in an apparatus configuration equipped with a plurality of ultraviolet irradiation furnaces other than the ultraviolet irradiation furnace 11 in the first stage, as shown in FIG. Some ultraviolet irradiation furnaces arranged next to the first stage ultraviolet irradiation furnace are equipped with a quartz tube 22, a gas supply equipment 41, and a gas recovery equipment 43 to purge the periphery of the optical fiber 3 with an inert gas. It is good also as a structure which performs ultraviolet irradiation in a state.

The coloring machine 2 shown in FIG. 2 is an improvement of a part of the coloring machine 1 shown in FIG. 1. Among the two ultraviolet irradiation furnaces 14 and 16 other than the first stage ultraviolet irradiation furnace 11, the first stage ultraviolet irradiation is performed. The ultraviolet irradiation furnace 14 provided next to the furnace 11 is equipped with a quartz tube 22, a gas supply equipment 41 and a gas recovery equipment 43, and the ultraviolet irradiation is performed in a state where the periphery of the optical fiber 3 is purged with an inert gas. It is set as the structure which performs.
With such a configuration, it is possible to more reliably cure the surface of the coloring ultraviolet curable resin 4 and more reliably prevent the occurrence of curing failure due to oxygen inhibition of the coloring ultraviolet curable resin 4. .

In the coloring machine 2 shown in FIG. 2, there are two ultraviolet irradiation furnaces equipped in addition to the first stage ultraviolet irradiation furnace 11, and the first stage ultraviolet irradiation furnace 14 is an inert gas around the optical fiber 3. The final ultraviolet irradiation furnace 16 was configured to irradiate ultraviolet rays without purging the periphery of the optical fiber 3 with an inert gas.
However, when the ultraviolet irradiation furnace equipped in addition to the ultraviolet irradiation furnace 11 in the first stage is composed of three or more ultraviolet irradiation furnaces, the ultraviolet irradiation that irradiates the ultraviolet rays without purging the periphery of the optical fiber 3 with an inert gas. The furnace may be restricted only to the last stage ultraviolet irradiation furnace to be cautious by preventing the occurrence of oxygen inhibition.

  In order to confirm the operation and effect of the present invention, the inventors of the present invention have confirmed that the first embodiment using the coloring machine 1 shown in FIG. 1 and the second embodiment using the coloring machine 2 shown in FIG. Comparative Example 1 in which the periphery of the optical fiber 3 is purged with an inert gas in all of the three ultraviolet irradiation furnaces shown in FIG. 1 and ultraviolet irradiation is performed, and in all of the three ultraviolet irradiation furnaces shown in FIG. In Comparative Example 2 in which ultraviolet irradiation was performed without purging the periphery of 3 with an inert gas, a coloring process was performed on the optical fiber 3 of 10 km.

Here, N ₂ gas is used as an example of the inert gas, and the gas supply equipment 41 for supplying N ₂ gas to the ultraviolet irradiation furnace supplies gas to the ultraviolet irradiation furnace 11 equipped as the first stage ultraviolet irradiation furnace. the first stage and N ₂ gas supply system, and N ₂ gas supply system of the second stage gas supplied to the first stage of the ultraviolet radiation furnace 14 of the ultraviolet irradiation furnace equipped in addition the first stage of the ultraviolet radiation furnace 11, end It was individually configured with a third stage N ₂ gas supply system for supplying gas to the stage ultraviolet irradiation furnace 16, and an inert gas was supplied at a flow rate of 80 liters per minute for each system.

The amount of N ₂ gas supplied in each gas supply system in Examples 1 and 2 and Comparative Examples 1 and 2 is shown in Table 1 below.

Of Examples 1 and 2 and Comparative Examples 1 and 2, except for Comparative Example 2, the optical fiber 3 was colored well.
In the case of the comparative example 2, when the optical fiber 3 coated with the ultraviolet curable resin 4 for coloring passes through the ultraviolet irradiation furnace 11 at the first stage, the resin coating is caused by oxygen inhibition by oxygen in the air filled in the furnace. It was not cured, and the uncured resin adhered to the equipment, and coloring production was impossible.

For Comparative Example 1 and Examples 1 and 2 in which coloring was good, the resin coating as a colored layer was subjected to FT-IR value measurement and a color peeling test to investigate the coating characteristics.
The results are shown in Table 2 below.

In Table 2 above, FT-IR value measurement is a method of confirming the degree of cure by comparing the absorption spectra before and after curing of the ultraviolet curable resin. The acceptable value is 0.18 to 0.34.
In Table 2, the color peeling test is a test for confirming whether the colored layer is peeled off from the optical fiber by peeling the optical fiber after the periphery of the optical fiber after being colored is cured with a tape resin. It is. If there is no peeling, it is acceptable.

As is clear from Table 2, the ultraviolet irradiation is performed without purging the periphery of the optical fiber 3 with an inert gas in part or all of the two ultraviolet irradiation furnaces 14 and 16. , 2 are FT-IR values and color peeling as compared with Comparative Example 1 in which the periphery of the optical fiber 3 is purged with an inert gas and irradiated with ultraviolet rays in all of the two ultraviolet irradiation furnaces 14 and 16. In all of the tests, good results without inferiority were obtained.
Moreover, from the results of Table 2, it can be said that according to the present invention, it is possible to obtain an optical fiber having a quality (curing degree) equal to or higher than the case of purging all ultraviolet irradiation furnaces with an inert gas. Then, it can be said that curing is difficult to proceed thereafter, and the change with time of the coating of the optical fiber after coloring is suppressed, and long-term storage becomes possible. For example, it is possible to prevent the curing reaction from proceeding further by irradiation with light such as an electric lamp during storage. The reason for the improvement in the degree of curing may be that the in-furnace temperature is increased by not flowing an inert gas, and the curing reaction is easily promoted.
That is, in Examples 1 and 2 described above, the effect of the present invention is that the resin coating can be satisfactorily formed without causing poor curing of the resin coating and the consumption of the inert gas can be reduced.・ The effect was confirmed.
The reduction rate of the consumption amount of the inert gas is about 66% in Example 1 and about 33% in Example 2. The effect of reducing the manufacturing cost due to the reduction of the consumption amount of the inert gas is remarkable.

As described above, the present invention is not limited to the color treatment of the optical fiber, but can be used as a general-purpose wire coating and curing method for forming a resin coating on various metal or non-metal wires. At that time, the number (quantity) of the ultraviolet irradiation furnace equipped as the ultraviolet curing furnace for surface curing and the number (quantity) of the ultraviolet irradiation furnace equipped as the internal curing ultraviolet irradiation furnace are shown in the above embodiment. The present invention is not limited to the quantity and can be similarly applied when there are a plurality of ultraviolet irradiation furnaces.
The method of coating and curing the optical fiber of the present invention is, in short, a part or all of the ultraviolet irradiation furnace other than the first stage as long as the first stage ultraviolet irradiation furnace and the subsequent ultraviolet irradiation furnace are individually equipped. This can be realized by carrying out the ultraviolet irradiation treatment without purging with an inert gas.

It is a schematic block diagram of one Embodiment of the coloring machine which enforces the coating hardening method of the optical fiber which concerns on this invention. It is a schematic block diagram of other embodiment of the coloring machine which enforces the coating hardening method of the optical fiber which concerns on this invention.

Explanation of symbols

1 Coloring machine 2 Coloring machine 3 Optical fiber (wire)
4 UV curable resin 5 Colored dice 11 First stage UV irradiation furnace 14, 16 UV irradiation furnace other than the first stage 21 Furnace case 23 UV 25 UV irradiation means 31 Die body 32 UV curable resin liquid 41 Gas supply equipment 43 Gas recovery equipment

Claims (2)

A method of coating and curing an optical fiber in which an ultraviolet curable resin for coloring applied to the outer periphery of an optical fiber is cured by a multi-stage ultraviolet irradiation furnace,
Among the ultraviolet irradiation furnaces provided in a plurality of stages, one or a plurality of ultraviolet irradiation furnaces including an ultraviolet irradiation furnace located in the first stage after the application of the coloring ultraviolet curable resin is applied to the optical fiber. With the surroundings purged with an inert gas, the colored ultraviolet curable resin applied to the optical fiber is irradiated with ultraviolet rays,
In addition, at least one of the one or a plurality of ultraviolet irradiation furnaces not including the ultraviolet irradiation furnace located in the first stage after the application of the coloring ultraviolet curable resin is an inert gas around the optical fiber. A method for coating and curing an optical fiber, comprising: irradiating the colored ultraviolet curable resin applied to the optical fiber without irradiating with ultraviolet light. Of the ultraviolet irradiation furnaces installed in the plurality of stages, only the ultraviolet irradiation furnace located in the first stage after applying the ultraviolet curable resin for coloring is in a state where the periphery of the optical fiber is purged with an inert gas. , Irradiating the ultraviolet curable resin for coloring applied to the optical fiber strand with ultraviolet rays,
In addition, all the ultraviolet irradiation furnaces that do not include the ultraviolet irradiation furnace located in the first stage after the application of the coloring ultraviolet curable resin are used without purging the periphery of the optical fiber strand with an inert gas. 2. The method of coating and curing an optical fiber according to claim 1, wherein the colored ultraviolet curable resin applied to the fiber strand is irradiated with ultraviolet rays.

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