JP2012073124A - Adhesion strength evaluation method and adhesion strength evaluation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesion strength evaluation method for quantitatively evaluating adhesion strength between coating films and base materials of laminates in which the composition of the coating films or the film thickness of the coating films are different.SOLUTION: After a blade 21 is pushed against an end surface D of a laminate 1, in which a coating film 11 is applied to the surface of a base material 12, the blade 21 is moved in parallel with a surface A of the coating film 11 (laminate 1) to obtain a peel load value between the coating film 11 and the base material 12 and a cutting load value of the coating film 11. A load value required for a cut in the thickness direction of the coating film 11 and deformation of a test piece (coating film 11 peeled from base material 12), which is obtained from a product of the cutting load value, gradient of a linear function of the depth from the surface A of the coating film 11 (laminate 1) to a cut surface, and the film thickness of the coating film 11, is subtracted from the peel load value, by which an adhesion load value between the coating film 11 and the base material 12 is obtained.

Description

  The present invention relates to a method for evaluating adhesion strength between a coating film and a substrate, and an apparatus for evaluating adhesion strength of a laminate in which a coating film is uniformly applied to the surface of the substrate.

  As a method for evaluating the adhesion strength between the coating film and the substrate, a cross-cut method (JIS K5600-5-6) and a peel test method (JIS K6854-1) are known. The cross-cut method is a method in which a tape is applied to the surface of a coating film in which a grid-like cut is formed, and the adhesion strength between the coating film and the substrate is evaluated according to the peeling condition of the coating film when the tape is peeled off. is there. The peel test method is an evaluation method in which the coating film and the substrate are peeled off, and the load value necessary for peeling is used as the adhesion strength between the coating film and the substrate. These methods cause problems when the adhesion strength between the coating film and the substrate is strong. Specifically, the cross-cut method has a problem that the coating film is not peeled off, and the peel test method has a problem that one of the coating film and the base material is broken, so that the adhesion strength cannot be evaluated.

  In order to solve the above problem, a method is used in which the coating film is peeled by moving the blade applied to the coating film in a straight line, and the adhesion strength is obtained from the load value applied to the blade at this time. This method is disclosed in Japanese Patent Application Laid-Open No. 61-169745 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2005-283215 (Patent Document 2).

JP 61-169745 JP 2005-283215 A

  In the method of Patent Document 1, since the width of the coating film is larger than the width of the blade, the force necessary for the side surface of the blade to tear the thickness direction of the coating film is included in the measured load value. For this reason, the adhesion strength of the laminated body from which the composition of a coating film and the film thickness of a coating film differ cannot be compared. Further, in the method of Patent Document 2, the side surface of the blade is prevented from tearing the coating film by cutting into the coating film so that the width of the coating film to be peeled is equal to the width of the blade. May be difficult to process such a coating.

  Moreover, in the method of patent document 1 and patent document 2, since the peeled test piece raise | generates deformation | transformation, such as curvature and compression, force required for a deformation | transformation of a test piece is contained in a measured load value. For this reason, the adhesion strength of the laminated body from which the composition of a coating film and the film thickness of a coating film differ cannot be compared.

  The present invention seeks to solve the above problems. That is, an object of the present invention is to provide an adhesion strength evaluation method for quantitatively evaluating the adhesion strength between a coating film and a substrate of a laminate having different coating film compositions and coating film thicknesses.

  In order to solve the above-mentioned problems, the invention of claim 1 is a method for evaluating the adhesion strength between a coating film of a laminate in which a coating film is uniformly applied to the surface of a substrate and the substrate, and comprising an end face of the coating film The first step of measuring the peel load value between the coating film and the substrate by moving the blade parallel to the surface of the coating film after the blade is pressed to peel the coating film from the substrate, After the blade is pressed against the end face, the blade is moved in parallel with the surface of the coating to cut the surface of the coating, and the cutting load value of the coating is measured, and the cutting in the second step Calculate the load value required for tearing in the thickness direction of the coating and deformation of the specimen from the product of the slope of the linear function of the depth from the coating surface to the cutting surface and the coating thickness. By subtracting the load value in the third step from the peel load value in the third step and the first step, the adhesion load between the coating film and the substrate Characterized in that it comprises a fourth step of finding the.

  According to a second aspect of the present invention, in the adhesion strength evaluation method according to the first aspect, an angle θ1 formed between the end surface of the laminated body against which the blade is pressed and the back surface of the laminated body is 20 ° or more and 70 ° or less. It is a range.

  According to a third aspect of the present invention, in the adhesion strength evaluation method according to the first or second aspect, an angle θ2 formed between the end face pressing the blade and the blade on a plane viewed from above the coating film is 35 ° or more and 70. It is within the range of ° or less.

  Invention of Claim 4 is an apparatus which evaluates the adhesive strength between the coating film of a laminated body which apply | coated the coating film uniformly on the surface of the base material, and a base material, Comprising: The mounting direction was faced to the perpendicular direction The stage on which the substrate of the laminate is fixed, the blade that can move relative to the stage in the horizontal and vertical directions, and the blade is moved parallel to the surface of the paint film after pressing the blade against the end face of the paint film When the coating film is peeled off from the substrate, and when the blade is pressed against the end face of the coating film, the blade is moved in parallel with the coating film surface to cut the coating film surface. A horizontal load detector for detecting a load in each direction.

  According to the method and apparatus of the present invention, the adhesion strength between a coating film and a substrate of a laminate can be quantitatively evaluated even in a laminate having a different coating composition or coating film thickness.

  Moreover, according to this invention of Claim 2 and Claim 3, it can peel easily in the interface between the coating film and base material of a laminated body.

It is a schematic cross section of the laminated body concerning this invention. It is a model top view for demonstrating the adhesion strength evaluation method of the laminated body concerning this invention. It is a model side view for demonstrating the adhesion strength evaluation method of the laminated body concerning this invention. It is an example of the graph of the load value with respect to the moving distance of the blade obtained when performing the 1st process or 2nd process of this invention with respect to the laminated body. It is a schematic diagram of the laminated body after performing the 1st process or the 2nd process of this invention with respect to a laminated body. It is an example of the graph of the cutting load value with respect to the depth from the surface of a coating film to the peeling surface obtained when performing the 2nd process of this invention with respect to a laminated body. It is a graph of the peeling load value with respect to the peel test result obtained when the 1st process of this invention was performed with respect to the laminated body. It is a graph of the adhesion | attachment load value with respect to the peel test result obtained when performing the adhesion strength evaluation method of this invention with respect to a laminated body.

  Hereinafter, embodiments of the method and apparatus for evaluating the adhesion strength of a laminate according to the present invention will be described with reference to FIGS.

First, the laminate to be evaluated in the present invention will be described with reference to FIG.
The laminate 1 has a configuration in which a coating film 11 is provided in the upper layer and a base material 12 is provided in the lower layer. The coating film 11 is a film having a uniform component and film thickness. The surface in contact with the coating film 11 of the substrate 12 is smooth. The uppermost surface of the laminate 1 is referred to as a front surface A, the lowermost surface of the laminate 1 is referred to as a back surface C, and the interface between the coating film 11 and the substrate 12 is referred to as an interface B. Moreover, the surface except the surface A and the back surface B among the surfaces of the laminated body 1 is defined as an end surface D.

Hereinafter, the adhesion strength evaluation method of the present invention will be described.
In the present invention, the blade 21 (see FIG. 2) is pressed against the end face D of the coating film and then moved to peel the coating film 11 from the substrate 12, and the peel load value between the coating film 11 and the substrate 12 is measured. And a second step of measuring the cutting load value of the coating film 11 by cutting the surface A of the coating film 11 by moving after pressing the blade 21 against the end face D of the coating film. .

Hereinafter, the first step will be described with reference to FIGS.
First, as shown in FIG. 3, the laminate 1 with the back surface C facing the stage 22 is fixed on the stage 22 using an adhesive or the like. Next, the blade 21 is pressed against the end surface D so that the tip of the blade 21 touches the vicinity of the interface B. At this time, the width direction of the blade 21 (the front and back direction in FIG. 3) is set to be parallel to the extending direction of the interface B on the end surface D. Thereafter, the blade 21 is moved in a straight line parallel to the interface B relative to the laminated body 1, and the coating film 11 is peeled off from the substrate 12. In this case, the blade 21 is moved in the arrow X1 direction parallel to the interface B, or the stage 22 is moved in the arrow X2 direction parallel to the interface B. At this time, as shown in FIG. 3, the horizontal load detector 23 such as a load cell connected to the blade 21 moves the blade 21 and removes the coating film 11 from the substrate 12 in the X2 direction. Is recorded with respect to the time or the moving distance of the blade 21.

  An example of the load value recorded by the horizontal load detector 23 in the first step is shown in FIG. FIG. 4 shows the movement distance of the blade 21 on the horizontal axis and the load value (strength) in the X2 direction applied to the blade 21 on the vertical axis. The load value continues to show a constant value after moving a certain distance. In FIG. 4, the constant value continues to be shown after moving about 0.3 mm. The load value that continues to show this constant value is defined as a peel load value F1.

The shape of the laminated body 1 after the first step is shown in FIG. As shown in FIG. 5, after the operation of the first step, the coating film 11 is peeled off from the base material 12 to be rolled up as the test piece 31, and the test surface 32 is revealed. This test surface 32 becomes the interface B in the first step.
In peeling by the first step, since the width of the coating film 11 is larger than the width of the blade 21 in the left-right direction in FIG. 5, the side surface portion of the blade 21 is positioned inside the width of the blade 21. And the coating film 11 located on the outer side are cut in the thickness direction of the coating film 11. The cut portion becomes the cut portion 33 in FIG. Further, as a result of peeling in the first step, the test piece 31 is deformed such as warpage or compression.

The force required for tearing the coating film 11 and deforming the test piece 31 is included in the peel load value F1. When the load value representing the adhesion strength between the coating film 11 and the substrate 12 is F0 and the load value necessary for tearing the coating film 11 and deforming the test piece 31 is f, the following equation (1) is established.
F1 = F0 + f (1)
Since the load value f varies depending on the film thickness of the coating film 11 and the composition of the coating film 11, when comparing the adhesion strength of the laminates 1 having different film thicknesses of the coating film 11 and compositions of the coating film 11, the peeling load value F <b> 1. Cannot be used.

  Therefore, the load value f required for the tearing of the coating film 11 and the deformation of the test piece 31 is obtained in the second step, and is subtracted from the peeling load value F1 obtained in the first step, whereby the coating film 11 and the substrate 12 are obtained. The contact load value F0 is taken out.

Next, a 2nd process is demonstrated based on FIG.2 and FIG.3.
First, as shown in FIG. 2, the laminate 1 with the back surface C facing the stage 22 is fixed on the stage 22 using an adhesive or the like. Next, the blade 21 is pressed against the end surface D so that the tip of the blade 21 touches the end surface D on the coating film 11 side above the interface B. At this time, the width direction of the blade 21 (the front and back direction in FIG. 2) is set to be parallel to the extending direction of the interface B on the end surface D. Thereafter, the blade 21 is moved in a straight line parallel to the interface B relative to the laminate 1 to cut the surface A of the coating film 11. In this case, the blade 21 is moved in the arrow X1 direction parallel to the interface B, or the stage 22 is moved in the arrow X2 direction parallel to the interface B. At this time, as shown in FIG. 3, the horizontal load detector 23 such as a load cell connected to the blade 21 moves in the X2 direction while the blade 21 moves and cuts the surface A of the coating film 11. The load value is recorded with respect to time or the moving distance of the blade 21.
The above operation is performed a plurality of times while changing the depth from the surface A at the position where the tip of the blade 21 is pressed against the end surface D of the coating film 11.

  An example of the load value recorded by the horizontal load detector 23 in the second step shows a value as shown in FIG. 4 as in the first step. The load value that continues to show a constant value after moving a certain distance is defined as a cutting load value F2 in the second step.

The laminate 1 after the operation in the second step has the shape shown in FIG. 5 in the same manner as after the operation in the first step. As shown in FIG. 5, after the operation of the second step, the upper part of the coating film 11 is cut to be rolled up as the test piece 31, and the test surface 32 is revealed. The test surface 32 becomes a cross section of the coating film 11 in the second step.
Also in the second step, as in the first step, deformation of the coating film 11 by the side portion of the blade 21 and warping or compression of the test piece 31 occurs.

As shown in FIG. 6, the depth d from the surface A to the test surface 32 in the second step and the cutting load value F2 have a linear function relationship. In FIG. 6, the horizontal axis represents the depth d, and the vertical axis represents the cutting load value F2. When the slope of this linear function is a and the intercept is b, the relationship of the following equation (2) is established.
F2 = a × d + b (2)
A product a × d of the inclination a and the depth d represents a load value depending on the depth d in the cutting load value F2. Of the factors included in the cutting load value F <b> 2, the factor depending on the depth d is a load value necessary for the tearing of the coating film 11 and the deformation of the test piece 31. That is, the product a × d represents a load value necessary for the tearing of the coating film 11 and the deformation of the test piece 31.

In the product a × d, the product a × d0 in which the depth d is replaced with the film thickness d0 of the coating film 11 represents the load value f necessary for the tearing of the coating film 11 and the deformation of the test piece 31 in the first step. Therefore, the following expression (3) is established.
f = a × d0 (3)
From the equations (1) and (3), the following equation (4) is established.
F0 = F1-a * d0 (4)
That is, the inclination a is obtained from the result of the second step, the third step of obtaining the product a × d0 of the inclination a and the film thickness d0 of the coating film 11 is performed, and further the peeling load value F1 of the first step. By performing the fourth step of subtracting the product a × d0 from the contact load value F0 can be obtained.
That is, in the adhesion strength evaluation method of this embodiment,
In evaluating the adhesion strength between the coating film 11 and the substrate 12 of the laminate 1 in which the coating film 11 is uniformly applied to the surface of the substrate 12,
After pressing the blade 21 against the end face D of the coating film 11 (laminate 1), the blade 21 is moved along the surface A of the coating film 11 (laminate 1) to peel the coating film 11 from the substrate 12. A first step of measuring a peeling load value F1 between the coating film 11 and the substrate 12;
After the blade 21 is pressed against the end face D of the coating film 11 (laminate 1), the blade 21 is moved along the surface A of the coating film 11 (laminate 1), and the surface A of the coating film 11 (laminate 1). A second step of measuring the cutting load value F2 of the coating film 11;
The product of the cutting load value F2 in the second step and the slope a of the linear function of the depth d from the surface A of the coating film 11 to the cutting surface (test surface 32) and the film thickness d0 of the coating film 11 × a third step for determining a load value required for tearing the coating film 11 in the thickness direction and deforming the test piece 31 from d0;
A fourth step of obtaining the adhesion load value F0 between the coating film 11 and the substrate 12 is performed by subtracting the load value a × d0 in the third step from the peel load value F1 in the first step. .

  According to the adhesion strength evaluation method of the present invention, only the adhesion load value F0 necessary for peeling between the coating film 11 and the substrate 12 is quantitatively excluded except for the load value necessary for the tearing of the coating film 11 and the deformation of the test piece 31. Can get to. By using the adhesion load value F0, it is possible to compare the adhesion strengths of the laminates 1 having different coating film 11 thicknesses and coating film 11 compositions.

When the blade 21 is pressed against the end surface D in the first step and the second step, the blade 21 can be easily pressed against the end surface D by using the following method.
First, the blade 21 is applied to the surface A. Thereafter, the blade 21 is moved in the X2 direction or the stage 22 is moved in the X1 direction, and the blade 21 and the laminate 1 are sufficiently separated. Next, the blade 21 is moved in the Z direction by an amount equal to the film thickness of the coating film 11 in the first process and by an arbitrary depth smaller than the film thickness of the coating film 11 in the second process. The blade 21 can be pressed against the end surface D by moving the blade 21 in the X1 direction or the stage 22 in the X2 direction.

  In the first step and the second step, the test surface 32 coincides with the interface B in the first step by observing the test surface 32 with an optical microscope and measuring the depth from the surface A to the test surface 32. In the second step, it is necessary to check whether the test surface 32 has a cross section of the coating film 11.

  In obtaining the inclination a in the equation (2), the depth d from the surface A to the test surface 32 is used. From the surface A to the position where the tip of the blade 21 is pressed against the end surface D in the second step. The depth may not match the depth d. For this reason, it is better to measure the depth d from the surface A to the test surface 32 by performing a step measurement after the second step.

  The laminated body 1 fixed on the stage 22 is desirably in the following shape.

  The end face D of the laminate 1 preferably has an angle θ1 formed between the end face D against which the blade 21 is pressed and the back face C in a range of 20 ° to 70 °. By setting θ1 to a range from 20 ° to 70 °, not 90 °, the success rate of peeling at the interface B when the coating film 11 is peeled can be improved. In particular, when the coating film 11 is thick, the peeling success rate at the interface B can be improved by setting θ1 in the range of 20 ° to 70 °. In addition, when θ1 is 0 ° to less than 20 °, it is disadvantageous in that it is necessary to increase the area of the laminate 1 and the test time is long, and when θ1 is more than 70 ° to 90 °, This is disadvantageous in that the peeling of the interface B2 tends to fail.

The end surface D is preferably in a range where the angle θ2 formed by the end surface D against which the blade 21 is pressed and the blade 21 in a plane viewed from above the surface A is in the range of 35 ° to 70 °. By making θ2 in the range of 35 ° or more and 70 ° or less, the separation success rate at the interface B can be improved. If θ2 is 0 ° to less than 35 °, it is disadvantageous in that peeling at the interface B tends to fail, and if θ2 is more than 70 ° to 90 °, the area of the laminate 1 is increased. It is disadvantageous in that it requires and the test time is long.
As shown in FIG. 3, the adhesion strength evaluation apparatus of the present invention includes a stage 22 to which the substrate 12 of the laminated body 1 placed with the lamination direction oriented in the vertical direction is fixed, After the blade 21 is pressed against the end face D of the coating film 11 (laminated body 1) and the blade 21 that is relatively movable in the vertical direction, the blade 21 is moved along the surface A of the coating film 11 (laminated body 1). When the coating film 11 is peeled off from the substrate 12, the blade 21 is moved along the surface A of the coating film 11 (laminate 1) after pressing the blade 21 against the end face D of the coating film 11 (laminate 1). Thus, an apparatus provided with a horizontal load detector 23 for detecting a horizontal load applied to the blade 21 when the surface A of the coating film 11 (laminated body 1) is cut can be used.

  Examples of the thin film adhesion strength evaluation method of the present invention will be described below.

  As the laminated body 1, three types of laminated bodies in which a urethane resin having a thickness of 20 to 30 μm was applied to one surface of a base film having a thickness of 250 μm made of transparent polyethylene terephthalate were prepared. The urethane resin applied to the three types of laminates has different compositions and film thicknesses, and the adhesion strength between the base film and the urethane resin differs for each laminate. In addition, a peel test was performed on the three types of laminates in advance.

  Using the blade 21 having a width of 0.5 mm and a universal bond tester (manufactured by Daisy Corporation: series 4000), the adhesion strength evaluation method of the present invention was performed in the form as shown in FIGS. The urethane resin was used as the coating film 11 and the base film was used as the base material 12 and fixed on the stage 22 via a glass plate. At this time, the laminate was bonded to the glass plate using an epoxy adhesive, and the glass plate was adhered onto the stage 22 with a cellophane tape. The size of the laminate is about 5 cm wide and about 1 cm long, and after being bonded to a glass plate, it is processed with a razor blade so that θ1 is 20 ° to 70 ° and θ2 is 35 ° to 70 °. went. About each laminated body, the 1st process and 2nd process of this invention were performed by changing a place with respect to the edge | side of the same width direction. In the second step, the depth d was measured with a stylus type surface roughness meter.

  The result measured in the first step is shown in FIG. In FIG. 7, the horizontal axis represents the peel test result, and the vertical axis represents the peel load value F <b> 1 obtained in the first step. Since the composition and film thickness of the coating are different, there is no correlation between the peel test result and the peeling load value F1, as shown in FIG. 7, and the adhesion is only achieved by peeling the coating with a blade as in the first step. It can be seen that the strength cannot be evaluated.

  FIG. 8 shows the result of calculating the inclination a by performing the second step and determining the contact load value F0 from the equation (4). FIG. 8 shows the result of the peel test on the horizontal axis and the contact load value F0 obtained from the equation (4) on the vertical axis. As shown in FIG. 8, it was found that the contact load value F0 has a correlation with the peel test result.

  Further, when the adhesion strength evaluation method of the present invention was performed on a laminate that cannot be evaluated for adhesion strength in a peel test because the coating film was broken, the adhesion load value F0 was 0.44N.

  As mentioned above, since the film thickness of the coating film and the composition of the coating film are different, simply peeling the coating film with the blade does not correlate with the peel test, and the adhesion strength between the coating film of the laminate and the substrate Could not be evaluated quantitatively. However, by using the adhesion strength evaluation method of the present invention, it was possible to obtain a correlation with the peel test for laminates having different coating film thicknesses and coating film compositions, and to quantitatively evaluate the adhesion strength. . Moreover, also about the laminated body from which a coating film fractures | ruptures in a peel test, the adhesive strength was able to be obtained quantitatively by using the adhesive strength evaluation method of this invention.

  The adhesion strength evaluation method of the present invention can be used as a measurement method for quantitatively evaluating the adhesion strength between a coating film of a laminate and a substrate having different coating film thicknesses and coating film compositions.

DESCRIPTION OF SYMBOLS 1 ... Laminate 11 ... Coating film 12 ... Base material 21 ... Blade 22 ... Stage 23 ... Horizontal load detector 31 ... Test piece 32 ... Test surface 33 ... Ripped part A ... Surface of the laminate B: Interface between coating film and substrate C ... Back side of laminate D ... End face of laminate

Claims (4)

A method for evaluating the adhesion strength between a coating film and a substrate of a laminate in which the coating film is uniformly applied to the surface of the substrate,
A first step of measuring the peel load value between the coating film and the substrate by pressing the blade against the end face of the coating film and then moving the blade parallel to the surface of the coating film to peel the coating film from the substrate; ,
A second step of measuring the cutting load value of the coating film by cutting the surface of the coating film by moving the blade parallel to the surface of the coating film after pressing the blade against the end face of the coating film;
From the product of the cutting load value in the second step, the slope of the linear function of the depth from the coating surface to the cutting surface, and the coating film thickness, tearing in the coating thickness direction and deformation of the specimen A third step for determining the load value required for
A laminate comprising: a fourth step of obtaining a contact load value between the coating film and the substrate by subtracting the load value in the third step from the peel load value in the first step. The adhesion strength evaluation method.   2. The adhesion strength evaluation method according to claim 1, wherein an angle θ <b> 1 formed between an end face of the laminated body against which the blade is pressed and a back surface of the laminated body is in a range of 20 ° to 70 °.   The angle θ2 formed between the end face pressing the blade and the blade in a plane viewed from above the coating film is within a range of 35 ° or more and 70 ° or less. The adhesion strength evaluation method described. An apparatus for evaluating the adhesion strength between a coating film and a substrate of a laminate in which the coating film is uniformly applied to the surface of the substrate,
A stage on which the base material of the laminated body placed with the lamination direction facing the vertical direction is fixed;
A blade movable relative to the stage in the horizontal and vertical directions;
After pressing the blade against the end face of the coating film, the blade is moved parallel to the surface of the coating film to peel the coating film from the substrate, and after pressing the blade against the end face of the coating film, A horizontal load detector that detects the horizontal load on the blade when the blade is moved in parallel to cut the surface of the coating,
The adhesion strength evaluation apparatus of the laminated body characterized by comprising.

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