JP2009103514A - Painting defect inspection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a painting defect inspection method capable of detecting accurately existence of a painting defect, even when irregularities are formed on a substrate surface, when applying painting onto the substrate. <P>SOLUTION: The temperature of the surface, where a paint 2 is to be painted on the substrate 1 before being painted, is measured. The temperature of the surface, where the paint 2 is painted on the substrate 1 after being painted, is measured. The temperature difference before and after painting on the substrate 1 surface is derived from each measured result. The existence of a painting defect is determined, based on the derived temperature difference of the substrate 1 surface. As a result, the existence of painting defect on the substrate 1 can be detected, based on the temperature decline of the substrate 1 surface, caused by vaporization heat removed, when a solvent in the paint 2 is evaporated, after the application of the paint 2 onto the substrate 1. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a coating failure inspection method for detecting a coating failure when a paint is applied to the surface of an appropriate substrate, and particularly relates to a coating failure inspection method suitable for detecting a coating failure in a substrate having an uneven surface. It is.

  When coating various products such as outer wall products, it is necessary to inspect for the presence of coating defects in the product after coating.

  As a method for inspecting such a coating defect, there is a method of visually observing. However, particularly when a clear paint is applied, it may be difficult to visually determine the coating defect.

  Therefore, conventionally, as a method for inspecting coating failure, for example, as shown in FIG. 6A, the substrate 1 after applying the paint 2 is irradiated with light from the light source 8, and the reflected light is converted into the CCD camera 9 or the like. A method of detecting a change in gloss caused by coating unevenness by measuring at a point, a method of detecting a film thickness of the paint 2 on the base material 1 after coating with a laser displacement meter 10 as shown in FIG. Has been done.

  However, in the case of inspecting a coating defect in the substrate 1 having an uneven surface, in the method shown in FIG. 6A, the light irradiated to the substrate 1 is irregularly reflected by the uneven portion, and an accurate inspection is performed. In addition, the method shown in FIG. 6 (b) also makes it impossible to perform accurate film thickness measurement because the light emitted from the laser displacement meter 10 is scattered by the uneven portions of the substrate 1. There's a problem.

  Moreover, in patent document 1, paying attention to the temperature fall resulting from the vaporization heat being deprived by volatilization of the solvent in the coating material 2 on the surface of the base material 1 after coating, the surface temperature of the base material 1 after coating is set. There has been proposed a method of measuring and determining that a coating defect has occurred at a temperature higher than a certain value with respect to the average temperature of the surface of the substrate 1 obtained from the measurement result.

However, even with the method disclosed in Patent Document 1, there is a problem that a coating failure cannot be accurately detected when temperature unevenness is originally generated on the surface of the substrate 1. In particular, when unevenness is formed on the surface of the base material 1, the heat capacity of the base material 1 is partially different. Therefore, even if the thermal history over the entire base material 1 is equal, the surface temperature Unevenness occurred, and it was difficult to accurately detect poor coating.
JP-A-8-304036

  The present invention has been made in view of the above points. When a substrate is coated, the presence or absence of a coating defect is accurately detected even when unevenness is formed on the surface of the substrate. An object of the present invention is to provide a coating defect inspection method that can be applied.

  The coating defect inspection method according to claim 1 is a coating defect inspection method for inspecting a coating defect on the substrate 1 after painting, and measures the temperature of the surface to which the paint 2 on the substrate 1 before coating is to be applied. Then, the temperature of the surface of the base material 1 after coating on which the paint 2 is applied is measured, and the temperature difference before and after the coating on the surface of the base material 1 is derived based on each measurement result. It is characterized by determining the presence or absence of coating failure based on the temperature difference of the surface.

  The invention according to claim 2 is the method according to claim 1, wherein the base material 1 coated by a spray method using a plurality of spray guns 3 is an inspection object, and the temperature difference before and after the coating of the surface of the base material 1 is derived. Derives the distribution of the temperature difference on the surface of the base material 1 before and after coating, and determines whether or not there is a coating defect, the locus 5a, 5b, 5c and 5d are overlapped, and a region where an abnormal temperature difference occurs in the temperature difference distribution is determined as a region where a coating failure occurs, and the coating among the trajectories 5a, 5b, 5c and 5d is determined. It is characterized in that the spray gun 3 corresponding to the trajectory 5c overlapping with the defective area is determined to be the spray gun 3 causing the coating failure.

  The invention according to claim 3 derives the temperature difference before and after the coating of the surface of the base material 1 with the base material 1 coated by the spray method using the plurality of spray guns 3 as the inspection object. In this case, the distribution of the temperature difference on the predetermined line 7 on the surface of the substrate 1 before and after coating is derived, and when determining the presence or absence of coating failure, the temperature difference in the derived temperature difference distribution is determined. It is characterized in that the presence / absence of a coating failure is determined based on a value change pattern.

  According to a fourth aspect of the present invention, in the method for inspecting defective coating, when determining the presence or absence of defective coating, the presence or absence of partial disturbance in the change pattern of the temperature difference value is determined. It is determined that a coating failure has occurred on the base material 1 at a position corresponding to the region where the spray gun 3 is a spray gun 3 that has caused the coating failure. Features.

  In the coating failure inspection apparatus according to claim 5, in determining whether there is a coating failure in claim 3 or 4, the amplitude of the change in the value in the change pattern of the temperature difference value and the change in this value are determined. When at least one of the periods deviates from a predetermined allowable range, it is determined that a coating failure has occurred and an abnormality has occurred in the painting operation by the spray gun 3. .

  According to the first aspect of the present invention, after applying the coating material 2 to the base material 1, the base material is based on the temperature decrease of the surface of the base material 1 due to the heat of vaporization taken away when the solvent in the coating material 2 volatilizes. 1 can detect the presence or absence of coating failure, and the temperature drop at this time is the difference between the temperature of the substrate 1 before the coating 2 is applied and the temperature of the substrate 1 after the coating 2 is applied. Can be accurately determined whether there is a coating failure of the base material 1 regardless of the temperature unevenness originally existing in the base material 1 before coating, and in particular, a base material having unevenness on the surface. This is suitable for determining the presence or absence of coating failure in the base material 1 having a part having a partially different heat capacity such as 1.

  According to the second aspect of the invention, it is possible to detect the occurrence of a coating failure and to identify the spray gun 3 that has performed an abnormal operation that causes the coating failure among a plurality of spray guns 3. It is.

  According to the third aspect of the present invention, when the change pattern of the temperature difference value on the predetermined line 7 on the substrate 1 is disturbed as compared with the normal pattern, the coating failure occurs. Can be detected.

  According to the fourth aspect of the invention, the occurrence of a coating failure is detected based on partial disturbance in the change pattern of the temperature difference value, and an abnormality that causes a coating failure among the plurality of spray guns 3 is detected. It is possible to identify the spray gun 3 that has performed various operations.

  According to the fifth aspect of the present invention, the occurrence of a coating failure is detected based on the amplitude of the change in the value in the temperature difference value change pattern and the period of the change in the value, and the cause of the coating failure. It is possible to detect an abnormality in the moving speed of the spray gun 3 and the conveyance speed of the substrate 1.

  Hereinafter, the best mode for carrying out the present invention will be described.

  As the base material 1 to be coated in the present invention, an appropriate one can be used, and for example, a cement-based inorganic plate can be mentioned.

  The paint 2 for coating the base material 1 may be an appropriate one, but the paint 2 to be subjected to the coating defect inspection in the present invention contains a solvent such as water or an organic solvent. Examples include those in which volatilization of the solvent occurs when the is applied to the substrate 1.

  Examples of such a paint 2 include organic paints such as acrylic emulsion paints. The organic paint may be a colorless and transparent clear paint, or may be a colored paint containing an appropriate pigment or dye. In this case, for example, after applying the organic paint to the substrate 1 by spraying or the like, the film is formed by heating and drying at an appropriate condition according to the composition of the organic paint, for example, at 100 to 150 ° C. for 30 seconds or more. An organic coating film can be formed. The thickness of the organic coating film is not particularly limited, but is preferably in the range of 5 to 100 μm.

  Moreover, after forming an organic coating film on the substrate 1, an inorganic coating containing an ultraviolet absorber can be further applied to form a film. The clear coating film formed by this is provided, for example, for surface protection of the substrate 1 and improvement of weather resistance.

  As the inorganic coating material, an appropriate one can be used. For example, a silicon alkoxide system in which a condensation reaction catalyst such as polyorganosiloxane and alkyl titanate is added to silica dispersion oligomer solution of organosilane, or silica is further added. Paint or the like can be used.

  After applying such an inorganic coating, a clear coating film can be formed by forming a film by baking and drying at 60 to 120 ° C., for example. The thickness of the clear coating film is not particularly limited, but is usually formed as a thin film in the range of 1 to 10 μm.

  Moreover, as an outer-layer clear coating film which is formed by laminating on this clear coating film and has an ultraviolet absorption lower than that of the clear coating film, an inorganic coating film containing a photocatalyst can be exemplified. This outer layer clear coating film can be formed by applying an inorganic coating containing a photocatalyst to the surface of the clear coating film, and is formed, for example, for the purpose of improving the antifouling property of the substrate 1.

  As the inorganic paint containing a photocatalyst, an appropriate one can be used. For example, a silicon alkoxide paint used for forming the above clear coating film added with a photocatalyst such as titanium oxide can be used. it can.

  After applying such an inorganic coating, the outer layer clear coating film can be formed by baking and drying at 60 to 120 ° C., for example. Although the thickness of this outer layer clear coating film is not particularly limited, for example, it is formed in the range of 0.2 to 1.0 μm.

  FIG. 1 schematically shows an example of a process for performing a coating defect inspection when a substrate 1 is coated.

  In the example shown in the figure, the step of measuring the temperature of the surface on which the coating material 2 on the base material 1 before coating is to be applied while the plate-like base material 1 is transported by a transport mechanism such as a belt conveyor (first step). And a step of applying the paint 2 to the substrate 1 (second step), and a step of measuring the temperature of the surface of the substrate 1 on which the paint 2 is applied after the coating 2 is applied (third step). ) And pass sequentially.

  In the first step, a temperature measurement device such as a thermographic sensor or a radiation thermometer 4 is used to measure the temperature of the surface of the base material 1 to derive the temperature distribution of the surface of the base material 1. At this time, the temperature distribution in the entire surface of the surface of the base material 1 to which the paint 2 is applied is preferably derived.

  In measuring the surface temperature of the base material 1, for example, a plurality of radiation thermometers 4 are arranged above the base material 1 in a direction orthogonal to the transport direction of the base material 1. The surface temperature of the base material 1 below each radiation thermometer 4 can be periodically measured in synchronization with the movement of the base material 1. At this time, the conveyance speed of the base material 1 can be measured by an appropriate measuring device such as an encoder, and periodic temperature measurement by each radiation thermometer 4 can be performed based on the measurement result. When such a radiation thermometer 4 is used, the temperature distribution of the surface in a wide range of the substrate 1 can be measured at a lower cost than in the case where a thermographic sensor is provided.

  In the second step, the paint 2 is applied to the substrate 1 by an appropriate method such as a spray method, a curtain coater, or a roll coater. In the present embodiment, the paint 2 is applied by a spray method using a spray gun 3. In applying the paint 2 by the spray method, an appropriate method such as a fixed method, a reciprocating method, or a rotary method can be adopted. In this embodiment, a plurality of spray guns 3 are arranged along the conveying direction of the substrate 1. In addition, a reciprocating system is adopted in which the spray gun 3 is driven to reciprocate in a direction orthogonal to the transport direction by an appropriate mechanism in synchronization with the movement of the substrate 1 by the transport mechanism.

  In the third step, the temperature distribution of the surface of the substrate 1 on which the paint 2 is applied can be measured in the same manner as in the first step, and the temperature distribution can be derived.

  And from the temperature distribution of the surface of the base material 1 before application | coating of the coating material 2 obtained at the said 1st process and the temperature distribution of the surface of the base material 1 after application | coating of the coating material 2 obtained at the 3rd process, The distribution of the temperature difference on the surface of the substrate 1 before and after the application of 2 is derived.

  At this time, for example, in the third step, the radiation thermometer 4 is arranged in the same arrangement as the first step, and the temperature at the same position on the substrate 1 can be measured in the same cycle as the first step. . In this case, based on the measurement result at each measurement position on the substrate 1 in the first step and the measurement result at each measurement position on the substrate 1 in the third step, at the same position on the substrate 1. The difference between the temperature measured in the first step and the temperature measured in the third step can be derived for each measurement position on the substrate 1. Thereby, the distribution of the temperature difference on the surface of the substrate 1 can be derived.

  An example of the distribution of the temperature difference obtained before and after the coating of the surface of the substrate 1 is shown in FIG. Such a temperature difference distribution can be derived, for example, by processing the measurement results in the first step and the third step with an appropriate control device constituted by a personal computer or the like. The obtained temperature difference distribution can be displayed on a display device such as a display. In the illustrated example, the distribution of the temperature difference is displayed by color-coding according to the magnitude of the temperature difference for each measurement position on the substrate 1 measured by the radiation thermometer 4 or the like.

  Based on the distribution of the temperature difference obtained in this way, if the existence of a region where the temperature difference value is smaller than other regions is observed, a coating failure has occurred in that region Can be determined. This determination can be performed by, for example, the operator sequentially confirming the temperature difference distribution displayed on the display or the like. For example, the temperature difference threshold value is stored in the control device in advance, and the temperature difference distribution is When a temperature difference occurs that falls below the threshold value, the controller may determine whether a coating failure has occurred, and at this time, an alarm may be issued by automatic control by the controller.

  Here, when the coating material 2 is applied to the base material 1, the solvent in the coating material 2 volatilizes, whereby the heat of vaporization is removed from the base material 1, and thus the surface temperature of the base material 1 decreases. At this time, if the coating amount of the paint 2 is uneven on the surface of the substrate 1, the solvent volatilization is reduced in a portion where the coating amount of the coating material 2 is small or a portion where the coating material 2 is not applied. The temperature difference before and after application of 2 is reduced. In the present invention, it is possible to detect a coating failure by detecting such a region where the temperature difference is small.

  In addition, since the surface temperature of the base material 1 after application of the paint 2 is not used as a reference, the paint 2 is detected based on the temperature difference between the surfaces of the base material 1 before and after the application of the paint 2. It is possible to accurately detect the presence or absence of coating failure regardless of the surface temperature unevenness of the base material 1 existing before coating. For this reason, even if it is a case where unevenness in temperature is likely to occur on the surface of the base material 1 such as when the surface of the base material 1 is uneven, it is possible to accurately detect coating defects. is there.

  Further, in the case of detecting an inspection defect in this way, the distribution of the temperature difference on the base material 1 obtained as described above is applied to each spray gun 3 used for applying the paint 2 in the second step. The trajectories 5a, 5b, 5c, 5d may be overlapped. In the illustrated example, the trajectories 5a, 5b, 5c, and 5d of the spray guns 3 when the four spray guns 3 are used for reciprocal coating are superimposed on the temperature difference distribution. This temperature difference distribution and the trajectories 5a, 5b, 5c, 5d of the spray gun 3 are also superposed by the control device, and the result can be displayed by an appropriate display means such as a display.

  If it does in this way, it will determine with the spray gun 3 corresponding to the locus | trajectory 5c which overlaps with the area | region determined to be coating failure by temperature difference distribution being the spray gun 3 which caused the coating failure, and a failure or nozzle clogging. It is possible to identify the spray gun 3 in which an operation abnormality has occurred. In this case, by repairing or replacing the specified spray gun 3, it is possible to prevent the occurrence of subsequent coating defects.

  Moreover, when deriving the distribution of the temperature difference before and after the coating on the surface of the substrate 1, the distribution of the temperature difference over the entire surface of the substrate 1 is derived as described above, and the substrate 1 on the surface of the substrate 1 is also derived. The distribution of the temperature difference on the predetermined line 7 along the conveyance direction may be derived.

  In measuring the distribution of the temperature difference on the predetermined line 7, for example, in the first step and the third step, only one radiation thermometer 4 is provided at a position corresponding to the predetermined line 7. Then, each temperature on the line 7 is measured. Alternatively, as in the case shown in FIG. 1, a plurality of radiation thermometers 4 are provided in each of the first process and the third process, and only the measurement result by the radiation thermometer 4 corresponding to the predetermined line 7 is provided for each process. The temperature difference on the line 7 may be derived using The difference between the temperature measured in the first step at the same position on the predetermined line 7 and the temperature measured in the third step can be derived for each measurement position on the substrate 1. Thereby, the distribution of the temperature difference on the predetermined line 7 on the surface of the substrate 1 can be derived.

  Based on the change pattern of the temperature difference value in the temperature difference distribution on the predetermined line 7 obtained in this way, it is possible to determine the presence or absence of coating failure.

  FIG. 3A shows the coating areas 6a, 6b, 6b, 6b, 6b, 6b, 6b, 6b, 6b, 6b, 6b, 6b, 6b, 6b, and 6b- 6 for the coating 2 for each spray gun 3 on the substrate 1. 6c and 6d are shown. FIG. 3B shows an example in which the temperature difference distribution on the line 7 in the figure in the base material 1 is derived. At this time, the operation of each spray gun 3 is normal, the spray amount of the paint 2 for each spray gun 3 is uniform, each spray gun 3 reciprocates at a predetermined speed, and the substrate 1 is predetermined. In this case, the coating amount of the paint 2 on the line 7 changes in a certain pattern within a certain range. For this reason, the distribution of the temperature difference on the surface of the substrate 1 on the line 7 changes with a constant period and amplitude as shown in FIG.

  On the other hand, when there are some spray guns 3 in which the spray amount of the paint 2 is smaller than that of the other spray guns 3 due to nozzle clogging or the like, the coating regions 6a, 6b, 6c and 6d are shown in FIG. 4 (a), the application area 6b of the paint 2 by the spray gun 3 with a small spray amount becomes narrow, and the area where the application quantity of the paint 2 is small or the paint 2 is not applied on the substrate 1. A region occurs. In this case, in the distribution of the temperature difference on the surface of the base material 1 on the line 7, a region where the value of the temperature difference becomes smaller at a constant period as shown in FIG. 4B appears. When such a change pattern of the temperature difference value is disturbed, it is determined that a coating failure has occurred, and an operation abnormality has occurred in the spray gun 3 corresponding to the disorder of the change pattern. Can be determined. In addition, although the example when the spray amount of the specific spray gun 3 decreases is shown here, the region where the value of the temperature difference increases at a constant cycle appears conversely when the spray amount increases. In this case as well, it is possible to determine the occurrence of coating failure and to determine that an abnormal operation has occurred in the spray gun 3 corresponding to the disturbance of the change pattern.

  Such determination of coating failure and determination of abnormal operation of the spray gun 3 may be performed by the operator sequentially confirming the distribution pattern of the temperature difference on the predetermined line 7 displayed on the display or the like by the control device. Yes, for example, when the allowable range of the temperature difference value is set in the control device in advance based on the temperature difference distribution pattern during normal operation, and the temperature difference value amplitude exceeds the allowable range. In addition, it may be determined that a defective coating is generated by the control device, or that it is further determined that the spray gun 3 corresponding to the location where the abnormality of the amplitude has caused an abnormal operation. At the same time, an alarm may be issued by automatic control by the control device.

  At this time, the operator can stop the coating line, remove the base material 1 in which the coating failure has occurred, and repair or replace the spray gun 3 that is operating abnormally.

  In addition, when the conveyance speed of the base material 1 is abnormal or when the reciprocating speed of the spray gun 3 is abnormal, the period and amplitude of the temperature difference distribution pattern on the predetermined line 7 are changed. Will come. For example, when the reciprocating speed of the spray gun 3 becomes lower than a predetermined speed, the coating areas 6a, 6b, 6c, and 6d are as shown in FIG. The length in which the base material 1 advances becomes longer. In this case, the distribution pattern of the temperature difference on the surface of the base material 1 on the line 7 increases the amplitude of the value of the temperature difference and the period of change of this value as shown in FIG. When such a change pattern of the temperature difference value is disturbed, it can be determined that a coating failure has occurred. Here, an example is shown in which the reciprocating speed of the spray gun 3 is slow, but conversely, when the reciprocating speed of the spray gun 3 is fast, or the conveyance speed of the substrate 1 is slowed or fast. Even in the case where the temperature difference is detected, the period and amplitude change in the distribution pattern of the temperature difference on the surface of the substrate 1 on the line 7 accordingly. Based on such disturbance of the change pattern of the temperature difference value, it is possible to determine the occurrence of coating failure due to an abnormality in the reciprocating speed of the spray gun 3 or the conveyance speed of the substrate 1.

  The determination of such a coating failure and the determination of the reciprocating speed of the spray gun 3 or the abnormality of the conveying speed of the base material 1 are performed by the operator using the pattern of the temperature difference distribution on the predetermined line 7 displayed on the display or the like. Although it can be performed by sequentially confirming, for example, based on the temperature difference distribution pattern during normal operation, the allowable range of the temperature difference value and the allowable range of the period are set in the control device in advance. Alternatively, when the cycle exceeds the allowable range, it is determined by the control device that a coating failure has occurred, or further, it is determined that an abnormality has occurred in the reciprocating speed of the spray gun 3 or the conveying speed of the substrate 1. May be. At the same time, an alarm may be issued by automatic control by the control device.

  At this time, the operator stops the coating line, removes the base material 1 in which the coating failure has occurred, checks the transport mechanism of the base material 1 such as a conveyor belt, and the mechanism for reciprocating the spray gun 3, and is necessary. Repairs can be made according to the situation.

  The coating defect inspection method described above can be performed by appropriately combining a plurality of inspection methods.

  After performing such a coating inspection, the substrate 1 on which no coating failure has been detected is subjected to heat treatment for film formation or various post-treatments as necessary.

It is a schematic perspective view which shows an example of embodiment of this invention. It is explanatory drawing which shows the example of distribution of the temperature difference before and behind the coating of the base-material surface derived | led-out in this invention. (A) is a schematic plan view showing an example of a coating region of each spray gun on a base material, and (b) is an example in which a distribution of temperature differences on a predetermined line on this base material is derived. It is a graph to show. (A) is a schematic plan view showing another example of the coating region of each spray gun on the substrate, and (b) is an example in which a distribution of temperature differences on a predetermined line on this substrate is derived. It is a graph which shows. (A) is a schematic plan view showing still another example of the coating area of each spray gun on the substrate, and (b) is a distribution of temperature difference on a predetermined line on this substrate. It is a graph which shows an example. (A) And (b) is a schematic sectional drawing which shows the example of a prior art.

Explanation of symbols

1 base material 2 paint 3 spray gun 5a, 5b, 5c, 5d locus 7 lines

Claims (5)

A coating defect inspection method for inspecting a coating defect on a substrate after painting,
Measure the temperature of the surface on which the paint on the substrate before coating is to be applied,
Measure the temperature of the coated surface of the base material after painting,
Based on each measurement result, the temperature difference before and after the coating of the substrate surface is derived,
A coating failure inspection method, wherein the presence or absence of a coating failure is determined based on the derived temperature difference of the substrate surface. Substrates painted by spraying using multiple spray guns are targeted for inspection.
When deriving the temperature difference between before and after painting on the substrate surface, derive the distribution of temperature difference on the substrate surface before and after painting,
When determining the presence or absence of coating defects, the trajectory of each spray gun on the surface of the substrate is superimposed on the temperature difference distribution, and areas with abnormal temperature differences in the temperature difference distribution are painted poorly. It is determined that the spray gun corresponding to the trajectory that overlaps the region in which the poor coating is generated among the trajectories is determined to be the spray gun that has caused the defective coating. The coating defect inspection method according to claim 1. Substrates painted by spraying using multiple spray guns are targeted for inspection.
When deriving the temperature difference before and after the coating of the substrate surface, the distribution of the temperature difference on the predetermined line of the substrate surface before and after the coating is derived,
The presence or absence of a coating defect is determined based on a change pattern of a value of a temperature difference in the derived temperature difference distribution when determining the presence or absence of a coating defect. Painting defect inspection method.   When determining the presence or absence of coating failure, determine the presence or absence of partial disturbance in the change pattern of the temperature difference value, the coating failure has occurred on the substrate at the position corresponding to the site where this disturbance has occurred 4. The coating failure inspection method according to claim 3, wherein the spray gun corresponding to the portion where the disturbance has occurred is determined to be a spray gun causing the coating failure.   When determining the presence or absence of coating failure, if at least one of the amplitude of the change of the value in the temperature difference value change pattern and the period of change of the value deviates from a predetermined allowable range, 5. The coating defect inspection method according to claim 3, wherein it is determined that a coating defect has occurred and an abnormality has occurred in a painting operation by a spray gun.

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