JP4020004B2 - Thin film adhesion strength evaluation method and adhesion strength evaluation apparatus - Google Patents

Description

【００２１】
表１から、耐光性試験０時間及び２４時間では薄膜（蒸着膜）の密着強度について碁盤目テープ法では差がないことがわかる。しかし本発明の薄膜密着強度測定方法によれば、耐光性試験０時間に対し、２４時間の方が剥離発生曲率が大きくなっていることから（図４）薄膜の密着強度が落ちていることがわかる。また同じ条件で耐光性試験を行った試験片に対し、３回の密着強度測定を行ったが、いずれも同じ傾向を示していることが図４からわかる。このように、本測定によれば密着強度の微小な差異が再現性よく、定量的に測定できる事が示された。
【００２２】
【発明の効果】
以上より、本発明の密着強度評価方法によれば、積層体の薄膜形成面を内側に湾曲させループ状にし、そのループ（湾曲部）が小さくなるようにしごき、薄膜の剥離が発生したときの曲率半径を測定するので、積層体及びその薄膜表面になにも触れさせることなく基材と薄膜との密着強度の測定をすることができ、得られた測定結果は再現性に優れている。また、密着強度の微小な差異を曲率半径の大きさとして定量的に示す事が可能となった。
【００２３】
【図面の簡単な説明】
【図１】従来の４点曲げ試験の概略図である。
【図２】本発明による薄膜の密着強度測定装置の実施の一例を示す説明図である。（ａ）は測定装置の側面図、（ｂ）は測定装置の正面図、（ｃ）は試験片の断面図である。
【図３】図３は湾曲部の曲率半径を求める際の概略図である。
【図４】図４は本測定方法で蒸着膜の剥離発生曲率を求めた測定結果である。
【符号の説明】
１１…歪ゲージ
１２…下部支点
１３…上部支点
１４…光学顕微鏡
２１…挟持移動冶具
２２…Ｚステージ
２３…Ｘステージ
２４…端部固定手段
２５…カメラ
３１…試験片（積層体）
３２…透明基材
３３…薄膜
４１…座標データ測定点[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an evaluation method and an evaluation apparatus for a laminate having one or more thin films on a flexible transparent substrate, and particularly the thin film adhesion in a transparent film having functionality such as a vapor deposition film. The present invention relates to an intensity evaluation method and an evaluation apparatus.
[0002]
[Prior art]
Conventionally, as a test method for evaluating the adhesion strength of a thin film to a substrate, there are a cross cut method, a cross cut tape method, and an X cut tape method as specified in JIS K5400. There are also bending tests in the standards of JIS, ASTM and ISO. A proposal for quantitatively and efficiently performing such a method has been made by Patent Document 1 or the like.
[0003]
[Patent Document 1]
JP-A-5-182255 [0004]
[Problems to be solved by the invention]
Among the conventional test methods, the cross-cut method is a method in which cuts reaching the base material through the thin film on the test piece are formed in a checkered pattern, and the adhesion state of the thin film is visually observed. However, visual observation of the adhesion state around the cut is not quantitative, and it is difficult to observe even a subtle difference in adhesion.
[0005]
In the cross-cut tape method, cuts reaching the base material through the thin film on the test piece are made in a cross-cut pattern, adhesive tape is applied on the cross-cut, and the thin film and the tape are adhered by rubbing with an eraser, and the tape is peeled off. This is a method of visually observing the state of adhesion of the thin film after the aging. However, in this method, when rubbing with an eraser to obtain adhesion between the thin film and the tape, the brittle film itself breaks, and there is a possibility that the accurate adhesive force cannot be measured. In addition, since the test method includes many artificial factors, there is a drawback that the test method itself has poor reproducibility.
[0006]
The X-cut tape method penetrates the thin film on the test piece, attaches the cut on X reaching the base material with a cutter knife, attaches a cellophane adhesive tape on it, peels it off, and between the base material or the thin film This is a method for examining the superiority or inferiority of adhesion. However, this method is not quantitative as the cross cut method and cross cut tape method, and there is a risk of damaging the film when rubbed with an eraser to obtain close contact with the cellophane adhesive tape. It has the disadvantage of being.
[0007]
The bending test will be described by taking the four-point bending test shown in FIG. 1 as an example. The test piece 31 to which the strain gauge 11 is attached is supported by two lower fulcrums 12, a load is applied by the upper fulcrum 13, and the peeled state and the strain (curvature radius) at that time are measured by the optical microscope 14. This method is a non-contact test, and the state of thin film peeling can be observed without touching the thin film. However, in the measurement with a test piece that is thin and has a small radius of curvature at which peeling occurs, the fulcrum interval becomes narrow, and observation and control of the fulcrum interval become difficult.
[0008]
The present invention has been made in view of the above-mentioned problems, and the object of the present invention is to provide a method for evaluating the adhesion strength of a laminate without causing any contact with the surface of the thin film and with good reproducibility, and adhesion. A strength evaluation apparatus is provided.
[0009]
[Means for Solving the Problems]
The present invention has been made in order to achieve the above object, and the first invention according to claim 1 provides a laminate having one or more thin films on a flexible transparent substrate. Curving the laminate with the thin film on the inside to form a curved portion, squeeze the curved portion to be smaller, and determine the radius of curvature of the curved portion when the thin film peels from the substrate, An adhesion strength evaluation method for a thin film, characterized in that the adhesion strength is evaluated based on the value of the radius of curvature.
[0010]
According to a second aspect of the present invention, after a laminate having one or more thin films on a flexible transparent substrate is bent with the thin film inside, a curved portion is formed and sandwiched . A thin jig comprising: a holding jig movable so as to reduce the bending portion; a bending portion observing means for observing a state of the bending portion; and a measuring means for measuring a radius of curvature of the bending portion. It is an adhesion strength evaluation device.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described below. First, the evaluation test apparatus shown in FIGS. 2 (a) and 2 (b) will be described. This device moves the clamping and moving jig 21 that clamps and curls the looped test piece, the end fixing means 24 that fixes both ends of the test piece, and the clamping and moving jig 21 in the Z direction, As a result, the Z stage 22 that will squeeze the test piece, the relative position of the bending portion observation means and the test piece are changed, and the bending portion observation means can observe the entire bending portion of the test piece. An X stage 23 that scans in the width direction of the test piece, an optical microscope 14 as a bending portion observation means for observing the state of the bending portion and detecting separation, and a radius of curvature of the bending portion for recording and measuring It consists of a camera 25. 31 is a test piece, that is, a laminate. Here, if the whole image of the test piece is within the field of view of the optical microscope, the X stage 23 may be omitted.
[0012]
Next, the test piece 31 will be described. The laminate that can be evaluated in the present invention is a laminate in which one or more thin films are laminated on a flexible transparent substrate. Specifically, a transparent moisture-proof film or the like on which a deposited film is formed can be mentioned.
[0013]
Such a laminate is cut into strips and evaluated as a test piece of the present invention. The shape of the test piece is not limited as long as the curved portion can be formed, and the curvature of the curved portion when the thin film is peeled off can be measured by squeezing to make it small. As shown in FIG. 2 (c), the test piece used in was obtained by cutting a laminate in which a thin film 33 was formed on a transparent substrate 32 into a rectangle having a width of 1 cm and a length of 12 cm using a cutter. The test piece 31 is bent in a loop shape so that the thin film 33 is on the inner side, is sandwiched by the sandwiching movement jig 21, and both ends of the test piece are fixed by the end fixing means 24. About the thin film of a test piece, not only a vapor deposition film but the thin film produced by various other thin film preparation methods, such as a thin film by sputtering, can be evaluated similarly.
[0014]
【Example】
Hereinafter, an example of a thin film adhesion strength measuring apparatus and a measuring method using the same according to the present invention will be described with reference to the drawings.
As shown in FIGS. 2 (a) and 2 (b), the set of test pieces is bent with a holding and moving jig 21 having a gap enough to finally pass the overlapped portions of both ends. Next, both ends of the test piece are aligned and fixed by the end fixing means 24 so as not to move in the height direction (Z-axis direction). In the embodiment of the present invention, the end portion is fixed with an adhesive tape, but there is no limitation as long as the purpose of fixing can be achieved without unnecessarily burdening the test piece such as an adhesive.
[0015]
The clamping movement jig 21 that clamps the test piece is fixed to the Z stage 22, and as the Z stage 22 moves upward, the clamping movement jig 21 also moves, the test piece 31 is squeezed, and the bending portion formed by the test piece is small. It will become. The movement of the Z stage is automatic, and the moving speed in this embodiment was set to 16 μm / sec. This moving speed can be set to an arbitrary value.
[0016]
The X stage 23 was set to 1 mm / sec so as to automatically reciprocate in the width direction of the test piece and move at a sufficiently high speed relative to the movement of the Z stage. If the moving speed is sufficiently faster than the moving speed of the Z stage 22, the moving speed of the X stage 23 is also arbitrary. As a result, it is possible to observe in real time (horizontal field of view 1.7 mm) with the optical microscope 14 when the thin film is peeled off at the bending portion of the test piece.
[0017]
The Z stage 22 was moved, and the test piece 31 was squeezed in the direction in which the curved portion (loop) was reduced. In this example, thin film peeling of the curved portion occurred by observation with the optical microscope 14, and movement in the Z direction was stopped when the peeling length reached half (0.6 mm) in the microscope visual field X-axis direction. In this embodiment, the peeling length is 0.6 mm. However, the measurer may arbitrarily set a criterion for ending the movement in the Z direction.
[0018]
The measurement of the radius of curvature was calculated by a dedicated application for photographing the curved portion of the test piece 31 with the digital camera 25 from the direction of FIG. At the time of measurement, as shown in FIG. 3, the radius of curvature with respect to the arc within a width of 2 mm was used as the measurement value with respect to the arc of the curved portion. The radius of curvature was obtained by extracting the shape of an arc as coordinate data and fitting a circle equation by the least square method.
[0019]
As a test piece, a vapor deposition film having a thickness of 300 nm was formed on a PET substrate having a thickness of 100 μm, and this was put into a light resistance tester (Suga Tester Long Life Fade Meter U48). The light resistance test time was 0, 24, and 48 hours, and the radius of curvature at which each peeling occurred was obtained by the method shown in the embodiment. The adhesion strength measurement test according to the present invention was performed three times each, and the results are shown in FIG. It is known that the adhesion strength between the PET substrate and the deposited film deteriorates depending on the light resistance test time, and this tendency was also confirmed from the adhesion strength measurement test according to the present invention. In addition, Table 1 shows the results of these test pieces evaluated by the cross-cut tape method. The number of squares peeled off indicates that “x / 100” means that peeling occurred in x squares per 100 squares.
[0020]
[Table 1]

[0021]
From Table 1, it can be seen that there is no difference in the cross-cut tape method for the adhesion strength of the thin film (deposited film) at 0 hours and 24 hours in the light resistance test. However, according to the thin film adhesion strength measuring method of the present invention, the peeling occurrence curvature is larger in 24 hours than in the light resistance test of 0 hours (FIG. 4). Recognize. Moreover, although the adhesive strength measurement was performed 3 times with respect to the test piece which performed the light resistance test on the same conditions, it turns out that all show the same tendency. Thus, according to this measurement, it was shown that minute differences in adhesion strength can be measured quantitatively with good reproducibility.
[0022]
【The invention's effect】
As described above, according to the adhesion strength evaluation method of the present invention, the thin film forming surface of the laminated body is bent inward to form a loop, and the loop (curved portion) is made small so that peeling of the thin film occurs. Since the radius of curvature is measured, the adhesion strength between the substrate and the thin film can be measured without touching the laminate and the surface of the thin film, and the obtained measurement results are excellent in reproducibility. In addition, it is possible to quantitatively indicate a minute difference in adhesion strength as the radius of curvature.
[0023]
[Brief description of the drawings]
FIG. 1 is a schematic view of a conventional four-point bending test.
FIG. 2 is an explanatory diagram showing an example of implementation of a thin film adhesion strength measuring apparatus according to the present invention. (A) is a side view of a measuring apparatus, (b) is a front view of a measuring apparatus, (c) is sectional drawing of a test piece.
FIG. 3 is a schematic diagram for obtaining a radius of curvature of a bending portion.
FIG. 4 is a measurement result obtained by obtaining a peeling occurrence curvature of a deposited film by this measurement method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Strain gauge 12 ... Lower fulcrum 13 ... Upper fulcrum 14 ... Optical microscope 21 ... Nipping movement jig 22 ... Z stage 23 ... X stage 24 ... End fixing means 25 ... Camera 31 ... Test piece (laminate)
32 ... Transparent substrate 33 ... Thin film 41 ... Coordinate data measurement point

Claims (2)

A laminated body having one or more thin films on a flexible transparent substrate is bent by forming the curved portion by bending the laminated body with the thin film inside, and the curved portion is reduced. A method for evaluating the adhesion strength of a thin film, comprising: obtaining a curvature radius of the curved portion when the thin film peels from the substrate, and evaluating the adhesion strength based on the value of the curvature radius. A laminate having one or more thin films on a flexible transparent substrate is bent with the thin film inside to form and sandwich a curved portion, and then the curved portion can be moved to be small. An apparatus for evaluating adhesion strength of a thin film, comprising: a sandwiching jig; a bending portion observation means for observing a state of the bending portion; and a measuring means for measuring a radius of curvature of the bending portion.

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