JP2013057536A - Inspection method of adhesive coating and metal piece - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inspection method of an adhesive coating, which allows the quality of the adhesive coating formed on the surface of a metal piece to be inspected using a simple device; and a metal piece having a high-quality adhesive coating.SOLUTION: An inspection method of an adhesive coating includes applying a voltage to a metal piece having an adhesive coating on the surface in an electrolyte so as to perform potential sweeping between a first potential more noble than the referential potential and a second potential between the referential potential and the first potential. Of the potential sweeping including a downward sweeping from the first potential to the second potential and an upward sweeping from the second potential to the first potential, at least the downward sweeping is performed. The quality of the adhesive coating is determined to be good when the color of the surface of the metal piece after the downward sweeping is more blackened compared to the color before the potential sweeping. The quality is determined to be bad when the color is not blackened.

Description

  The present invention relates to an inspection method for inspecting the quality of a coating on a metal piece having a surface-treated coating having adhesiveness on the surface, and an object of the inspection, wherein the adhesive coating is applied. Related to the metal piece. More specifically, for example, the present invention relates to an inspection method for an adhesive film formed on the surface of a metal piece in order to adhere a resin or the like to a terminal or an electrode of a secondary battery, and the metal piece.

  Conventionally, an adhesive surface treatment film such as an adhesive layer may be formed on the surface of a metal piece or the like. For example, in order to adhere a resin such as a seal member to the electrode of the secondary battery, an adhesive film may be formed on the electrode metal plate. As an example, Patent Document 1 discloses a current collector in which a synthetic resin layer is adhered to a metal foil with an adhesive layer interposed.

  Patent Document 2 discloses a technique for manufacturing a sealing plate for a battery container. This document discloses a technique for generating a coating film having high adhesion reactivity on a lid or an electrode terminal in order to bond an insulating sealing member made of resin between the lid of the battery container and the electrode terminal. (See paragraph [0055].)

JP 2008-41511 A JP 2007-179803 A

  However, even in the above-mentioned conventional documents, there is no description about a method for inspecting the quality of the formed film. If the quality of the coating is not good, the adhesion between the resin and the metal piece may be poor. As the quality of the adhesive coating, for example, it is required that the coating has a uniform thickness and uniform components and is adhered without gaps. Therefore, an inspection method for inspecting whether or not the adhesive coating is properly formed satisfying these conditions has been demanded.

  The present invention has been made to solve the problems of the prior art. In other words, the problem is that the adhesive film formed on the surface of the metal piece can be inspected with a simple device for the quality of the adhesive film, and the adhesive film has a good quality. To provide a piece of metal.

  The method for inspecting an adhesive coating of the present invention, which has been made for the purpose of solving this problem, applies a voltage in an electrolyte solution to a metal piece having an adhesive coating formed on the surface thereof, so that it is nobler than a reference potential. 1 is a method for inspecting an adhesive film by performing a potential sweep process between a first potential and a second potential between a reference potential and a first potential. In the potential sweep process, At least a downward sweep from the second potential to the second potential and an upward sweep from the second potential to the first potential, and the surface of the metal piece after the downward sweep has a color before the potential sweep process. On the other hand, it is judged that the quality of the adhesive coating is good when it is blackened, and it is judged that the quality is not good when it is not blackened.

  According to the method for inspecting an adhesive film of the present invention, a potential is swept in an electrolytic solution using a metal piece having an adhesive film on the surface as an object to be inspected. In particular, when the quality of the adhesive coating is good by sweeping downward from the first potential nobler than the reference potential to the second potential close to the reference potential, the color of the surface of the metal piece is blackened. It was found to be. If the quality of the adhesive film is not good, it will not be blackened even if the potential sweep process is performed. Therefore, it can be easily judged visually. Thereby, the quality of the adhesive film formed on the surface of the metal piece can be inspected with a simple device.

Furthermore, in the present invention, the potential sweep process is performed by sweeping the potential of the working electrode with respect to the reference electrode in a state where the metal piece is disposed on the working electrode and the base metal is disposed on the counter electrode and the reference electrode. The reference potential is preferably the reference electrode potential.
In this way, it is easy to sweep the potential.

Furthermore, in the present invention, in the potential sweep process, it is desirable to repeat the downward sweep and the upward sweep within a range of 2 to 4 times.
Even if it is not possible to confirm clear blackening by only one downward sweep, it can be easily judged by repeating 2 to 4 times. It does not make much sense to repeat more than 5 times.

  Furthermore, in the present invention, it is desirable to use the same electrolyte as that used in the battery using the same material as the metal piece for the negative electrode current collector. Moreover, it is desirable that the metal of the metal piece is copper. Further, it is desirable that the adhesive coating contains triazine.

  The present invention also relates to a metal piece having an adhesive film formed on the surface thereof, and by applying a voltage in the electrolytic solution, the first potential that is nobler than the reference potential, the reference potential, and the first potential. This also extends to the metal piece that becomes black when the potential sweep process is performed by sweeping the potential between the second potential and the second potential.

  According to the inspection method and metal piece of the adhesive film of the present invention, the quality of the adhesive film formed on the surface of the metal piece can be inspected with a simple device, and the adhesiveness with good quality can be checked. It is a metal piece having a coating.

It is explanatory drawing which shows the inspection apparatus of this form. It is a flowchart figure which shows the inspection method of this form. It is a graph which shows the CV curve at the time of test | inspecting the to-be-inspected object which has a film of favorable quality. It is a graph which shows the CV curve at the time of test | inspecting the to-be-inspected object which has a film of the quality which is not favorable.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present embodiment, the present invention is applied to an inspection method for inspecting the quality of an adhesion functional surface treatment film formed on a metal plate, for example, in an electrode plate used for a secondary battery.

  The object of inspection by the inspection method of the present embodiment is the quality of the surface treatment film having an adhesion function formed on the copper plate. This coating is a triazine polymer coating containing triazine, and is for adding an adhesive function with a PPS resin or the like to a copper plate. The copper plate provided with this coating is used, for example, for a negative electrode plate of a secondary battery. As a method for producing this type of coating, the methods described in paragraph [0055] of the above-mentioned Patent Document 2 and documents cited in the sentence can be used. In this embodiment, a copper plate piece provided with a triazine polymer coating on both sides is called an object to be inspected.

  The inspection method of this embodiment is performed using a cyclic voltammetry method (CV method). In other words, oxidation and reduction are repeated by sweeping the potential with the test object as the working electrode. According to this method, a cyclic voltammogram (CV curve) drawn by the current value flowing through the working electrode is obtained.

  As shown in FIG. 1, the inspection apparatus 10 that performs the inspection of this embodiment includes a triode cell 11 and a measuring instrument (potentiometer / galvanostat) 12. The three-electrode cell 11 of this embodiment has a working electrode 21, a reference electrode 22, and a counter electrode 23. An object to be inspected is disposed on the working electrode 21. Further, metallic lithium is disposed on both the reference electrode 22 and the counter electrode 23. Metallic lithium is suitable for use as a reference electrode 22 and a counter electrode 23 as a standard because its natural polarization potential is far from copper.

  As shown in FIG. 1, the inspection device 10 is sealed in a container 27 in a state where all the three electrodes are immersed in an electrolyte solution 25. As the electrolytic solution 25, the same electrolytic solution as that used for a lithium ion secondary battery using a copper plate coated with the film of the present embodiment as a negative electrode is used. For example, a nonaqueous electrolytic solution or an ion conductive polymer containing a lithium salt such as lithium hexafluorophosphate is suitable. As the electrolytic solution 25, not only a lithium ion secondary battery but also a general electrolytic solution used for other types of secondary batteries such as a metal lithium secondary battery can be used.

  The container 27 needs to be made of a material that is strong against the electrolytic solution 25. Further, the container 27 is preferably one that can observe the appearance color of the working electrode 21 from the outside. Therefore, a transparent or semi-transparent material is preferable. For example, glassware or polypropylene containers are suitable.

  The measuring instrument 12 of this embodiment performs a process of sweeping the potential to the working electrode 21 by applying a voltage to the working electrode 21 in the electrolytic solution and changing the voltage. Further, the measuring instrument 12 measures the value of the current flowing between the working electrode 21 and the counter electrode 23 while changing the voltage of the working electrode 21 with respect to the reference electrode 22. In this embodiment, as the process of sweeping the potential, a downward sweep for decreasing the applied voltage and an upward sweep for increasing the applied voltage are alternately performed.

  Therefore, the measuring instrument 12 has a power source 31 and an ammeter 32. The power supply 31 applies a negative voltage to the working electrode 21 with respect to the reference electrode 22. The measuring instrument 12 of this embodiment can change the voltage of the power supply 31. The ammeter 32 is for measuring a current value flowing between the working electrode 21 and the counter electrode 23.

  When the inspection is performed by the inspection method of this embodiment, the measuring device 12 sweeps the potential of the working electrode 21 with respect to the reference electrode 22 at a predetermined speed within a predetermined potential range. The predetermined potential range is within a range between a first potential that is noble than the reference potential that is the potential of the reference electrode and a second potential that is between the reference potential and the first potential. is there. The first potential is higher than the potential of the working electrode 21 in the natural state. The second potential is a potential close to the reference potential.

  For this purpose, the voltage of the power supply 31 is changed at a constant speed. For example, from the initial state, the voltage of the power supply 31 is lowered to a predetermined first voltage, and subsequently raised several times. This corresponds to reducing the working electrode 21 as the voltage decreases, and subsequently oxidizing the working electrode 21 by increasing the voltage. Thereby, oxidation and reduction of the working electrode 21 are repeatedly performed. This potential sweep process or oxidation and reduction process may be performed once, but it is desirable to repeat the process within a range of 2 to 4 times.

  By repeating the experiment, the present inventor has found that the object to be inspected is blackened by this potential sweep process only when the quality of the film is good. In other words, it was found that whether the quality of the film is good or bad can be determined by observing the appearance color of the inspection object while performing the potential sweep process. This is because the color of the surface of the metal piece after the potential sweep process is blackened in the metal piece having a good coating quality compared to the color of the surface of the metal piece before the potential sweep process.

  That is, it is possible to determine that the blackened material by the potential sweep process is an inspection object with good film quality. On the other hand, if the film quality is poor, it can be easily judged because it will not blacken even if the potential sweep process is repeated. Here, “blackening” indicates that the brightness of the surface color is reduced by 30% or more from the brightness before the potential sweep process. Alternatively, the determination may be made based on the reflectance of visible light. This change can be easily judged visually.

  The procedure of the inspection method of this embodiment is shown in the flowchart of FIG. In the inspection method of this embodiment, first, in S101, the above-described tripolar cell 11 is manufactured using the object to be inspected as the working electrode 21. Then, a measuring instrument 12 is connected to the triode cell 11. As a result, the inspection apparatus 10 shown in FIG. 1 is obtained.

  Next, in S102 of FIG. 2, the potential of the working electrode 21 with respect to the reference electrode 22 is swept from the natural potential to the lower limit value, subsequently swept to the upper limit value, and further returned to the natural potential. Thereby, the potential sweep process can be performed on the working electrode 21. Both the lower limit value and the upper limit value are predetermined values. Here, the lower limit value was set to 0.1V, and the upper limit value was set to 3.5V. In this embodiment, the potential sweep rate is 10 mV / sec.

  The lower limit value is the reduction potential and needs to be close to 0V to some extent, but should not be 0V. In this embodiment, the lower limit is in the range of 0.05 to 2V. More preferably, it is in the range of 0.1 to 1V. Further, the upper limit value is an oxidation potential, and it is preferable that the upper limit value be a value that can reliably perform the potential sweep process within a range in which the electrolytic solution is not decomposed. If the upper limit is too low, the effectiveness as a test is impaired, which is not preferable. In the present embodiment, the upper limit value is in the range of 2.5 to 4V. More preferably, it is in the range of 3 to 3.5V.

  Further, this potential sweep cycle between the lower limit value and the upper limit value is repeated three times in total. However, the sweep speed and the number of cycles are not limited to this. One cycle may lack certainty, but it is sufficient if it is two or more cycles. On the other hand, it does not make much sense to repeat more than 5 cycles. Therefore, the range of 2 to 4 cycles is preferable.

  Then, the appearance color of the working electrode 21 is observed during the cycle of S102 (S103). If the container 27 is transparent, it is preferable because observation can be performed simultaneously while performing a sweep cycle. In this case, it is determined whether or not the working electrode 21 is blackened during a period in which the potential is in the range of 0.1 V to 2.0 V (S104). In other words, this inspection object may or may not change to black.

  In the above-described potential sweep cycle, if the working electrode 21 is black (S104: YES), it is determined that the quality of the coating is good (S105). On the other hand, if the working electrode 21 is not black (S104: NO), it is determined that it is a defective product (S106). In this test, if the product is a non-defective product, the appearance color changes clearly, so it can be easily judged visually. In addition, that the quality of the coating is good means that the coating has a uniform thickness and uniform components and is adhered without any gaps. This is the end of the description of the procedure of this embodiment.

  Further, the value of the current flowing between the working electrode 21 and the counter electrode 23 during this cycle changed as in the example of the CV curve shown in FIG. This current value can be grasped by the ammeter 32. First, the voltage of the power supply 31 is lowered from the starting point of the current value of 0.0 mA and the potential value of 3.3 V to the lower limit value. Then, as the potential was lowered, the reduction process progressed, and a negative current flowed.

  The current value at this time changes to the left in the figure while changing as indicated by the thick solid line L1 shown in FIG. Then, the absolute value of the current value gradually increased, and after the absolute value exceeded 1.5 mA, the absolute value of the current value once decreased and then increased again. In other words, there was a peak in current value. In the example of this figure, there were two peaks.

  Subsequently, the voltage of the power source 31 was lowered to the lower limit of about 0.1 V, and then the voltage of the power source 31 was raised. Then, as the potential was increased, the oxidation process progressed, and a positive current value flowed. The current value at this time goes to the right along the thin solid line L2 in FIG. When the upper limit of about 3.5V is reached, one cycle is complete.

  When the upper limit was reached, the direction of voltage change was changed again as shown in FIG. In this example, three cycles were performed as indicated by L1-> L2-> L3-> L4-> L5-> L6 in the figure. This figure is an example of a CV curve of an object to be inspected with good inspection results, and the working electrode 21 of this example turned black within a range of 0.1 to 2V.

  For comparison, FIG. 4 shows an example of a CV curve of an object to be inspected whose test result is not good. In the example of this figure, the absolute value of the current value increased monotonously along the solid line L11 from the starting point of the current value of 0.0 mA and the potential value of 1.7 V, and no peak appeared. Thereafter, when the voltage was changed in the same manner as in the example of FIG. 3, the current value changed as indicated by L11.fwdarw.L12.fwdarw.L13.fwdarw.L14.fwdarw.L15, and no peak appeared anywhere. The working electrode 21 in this example did not turn black at any position during the three cycles. Although these curves partially overlap, they are not interrupted.

  As described in detail above, according to the inspection method of the present embodiment, the metal piece is subjected to the potential sweep process, and the appearance color of the surface is observed. If the appearance changes to black, it can be determined that the coating is good. Those that have not changed to black can be determined to be defective. Therefore, it can be easily discriminated visually. Therefore, the coating inspection method can easily inspect the quality of the coating formed on the surface of the metal piece.

In addition, this form is only a mere illustration and does not limit this invention at all. Therefore, the present invention can naturally be improved and modified in various ways without departing from the gist thereof.
In this embodiment, the potential sweep process is repeated about three times. However, it is desirable to perform at least one downward sweep process for decreasing the voltage. Since there is a thing which blackens only by performing a downward sweep process once, when blackening has been confirmed, processing may be ended at that time. However, even if the blackening cannot be clearly confirmed by one processing, it may be confirmed by repeating 2 to 3 times. Therefore, it is preferable to repeat about three times. On the other hand, if blackening does not occur even after repeated four times, it is appropriate to determine that the product is defective. Repeating five or more times does not make much sense.

DESCRIPTION OF SYMBOLS 10 Inspection apparatus 21 Working electrode 22 Reference electrode 23 Counter electrode 25 Electrolyte

Claims (7)

By applying a voltage in the electrolytic solution to the metal piece having the adhesive coating formed on the surface, a first potential that is noble than the reference potential and a second potential between the reference potential and the first potential are applied. In the method for inspecting an adhesive film by performing a potential sweep process with respect to the potential,
In the potential sweep process, at least the downward sweep is performed among a downward sweep from the first potential to the second potential and an upward sweep from the second potential to the first potential;
When the surface of the metal piece after the downward sweep is blackened compared to the color before the potential sweep process, it is determined that the quality of the adhesive coating is good, and the quality is good when it is not blackened. A method for inspecting an adhesive coating, characterized in that it is determined that there is no. The method for inspecting an adhesive film according to claim 1,
In the potential sweep process, the potential of the working electrode with respect to the reference electrode is swept in the electrolytic solution in a state where the metal piece is disposed on the working electrode and a base metal is disposed on the counter electrode and the reference electrode. It is done by
The method for inspecting an adhesive film, wherein the reference potential is a potential of the reference electrode. In the inspection method of the adhesive film of Claim 1 or Claim 2,
In the potential sweep process, the downward sweep and the upward sweep are repeatedly performed within a range of 2 to 4 times. In the inspection method of the adhesive film as described in any one of Claim 1- Claim 3,
A method for inspecting an adhesive film, characterized in that the same electrolyte as that used in a battery using a metal of the same material as that of the metal piece is used for a current collector for a negative electrode. In the inspection method of the adhesive film as described in any one of Claim 1- Claim 4,
The method for inspecting an adhesive film, wherein the metal of the metal piece is copper. In the inspection method of the adhesive film as described in any one of Claim 1- Claim 5,
A method for inspecting an adhesive film, wherein the adhesive film contains triazine. In a metal piece with an adhesive coating on its surface,
By applying a voltage in the electrolyte, the potential is swept between a first potential that is more noble than a reference potential and a second potential between the reference potential and the first potential. A metal piece characterized by being blackened when a potential sweep process is performed.

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