Method for measuring adhesive strength

Abstract

This application relates to a method for measuring adhesive strength. The method for measuring adhesive strength includes: setting an evaluation time (t...). e ); Fix the substrate and adhesive components to the measuring device; Use a first measuring force (F) e1 Pull the adhesive component fixed to the measuring device for the evaluation time (t) e ); using the second measuring force (F) e2 Pull the adhesive component fixed to the measuring device for the evaluation time (t) e ), of which the second measuring force (F) e2 ) is achieved by measuring the first force (F) e1 The amount is obtained by increasing a preset amount; and the reference measuring force (F) is determined. es The benchmark force (F) es ) is when the distance by which the first part of the adhesive component separates from the substrate is equal to a preset distance (d). t The static force applied to the bonded component at that time.

Description

Technical Field

[0001] The embodiments generally relate to apparatus and methods for measuring adhesive strength. More specifically, embodiments of the present invention relate to a method for measuring adhesive strength by using adhesion retention capacity. Background Technology

[0002] Display devices may include various adhesive components (or bonding components). For example, adhesive components with adhesive strength, such as protective films, optically clear adhesives (“OCA”), pressure-sensitive adhesives (“PSA”), optically clear resins (“OCR”), anisotropic conductive films (“ACF”), and double-sided adhesive tapes, may be included in the display device. Depending on the intended use, the adhesive components described above may have various adhesive properties.

[0003] The adhesive strength of bonded components can be measured using methods such as peel strength (measuring the average force applied during the peel interval), probe adhesive (measuring the maximum force applied per unit area during peel), shear stress (measuring shear strain), and holding force (measuring the degree to which a predetermined weight is borne within a predetermined time). Summary of the Invention

[0004] The adhesive component can be applied to the display device with reference to the above measurement scheme. However, even if the adhesive component selected with reference to the above measurement scheme is applied to the display device, defects in the adhesive component may occur, such as residues (e.g., sludge) remaining on the adhesive surface, or the adhesive component failing to maintain its adhesive strength when bent or repeatedly folded. Therefore, a new method for measuring the adhesive strength of the adhesive component is needed.

[0005] Some implementations provide a method for measuring adhesive strength by using adhesion retention capability.

[0006] According to some implementation methods, methods for measuring adhesive strength include: setting an evaluation time (t). e ); Fix the substrate and adhesive components to the measuring device; Use a first measuring force (F) e1 ) Pull the adhesive component fixed to the measuring device for the evaluation time (t) e ); using the second measuring force (F) e2 ) Pull the adhesive component fixed to the measuring device for the evaluation time (t) e The second measuring force (F) e2 ) is by measuring the first force (F) e1 The amount is obtained by increasing a preset amount; and the reference measuring force (F) is determined. es The benchmark force (F) es ) is when the distance by which the first part of the adhesive component separates from the substrate is equal to a preset distance (d). tThe static force applied to the bonded component at that time.

[0007] In an implementation, the method may further include: using a first measuring force (F) e1 ) Pull the adhesive component fixed to the measuring device for the evaluation time (t) e After that, the distance from which the first part of the adhesive component separated from the substrate was measured.

[0008] In an embodiment, the method may further include: after measuring the distance by which the first portion of the adhesive member separates from the substrate, comparing the distance by which the first portion of the adhesive member separates from the substrate with a preset distance (d). t (Compare)

[0009] In the implementation method, when using the first measuring force (F) e1 ) Pull the adhesive component fixed to the measuring device for the evaluation time (t) e When the tension increases from 0 to the first measured force (F), the tension can be increased from 0 to the first measured force (F). e1 ), and then the first measured force (F) e1 ) can be evaluated at time (t) e It remains constant during the period.

[0010] In an implementation, the method may further include: using a first measuring force (F) e1 The second measuring force (F) obtained by increasing the preset amount e2 ) Pull the adhesive component fixed to the measuring device for the evaluation time (t) e Before proceeding, reattach the substrate and adhesive components to the measuring device.

[0011] In an implementation, the method may further include: using a first measuring force (F) e1 The second measuring force (F) obtained by increasing the preset amount e2 ) Pull the adhesive component fixed to the measuring device for the evaluation time (t) e After that, the distance from which the first part of the adhesive component separated from the substrate was measured.

[0012] In an embodiment, the method may further include: after measuring the distance by which the first portion of the adhesive member separates from the substrate, comparing the distance by which the first portion of the adhesive member separates from the substrate with a preset distance (d). t (Compare)

[0013] In the implementation method, when using the second measuring force (F) e2 ) Pull the adhesive component fixed to the measuring device for the evaluation time (t) e When the tension increases from 0 to the second measuring force (F), the tension can be increased from 0 to the second measuring force (F). e2 ), and then the second measuring force (F) e2 ) can be evaluated at time (t)e It remains constant during the period.

[0014] In the implementation method, the first measuring force (F) is used. e1 ) Pull the adhesive component and use the second measuring force (F) e2 Pulling the adhesive components can be done independently.

[0015] In the implementation method, when using the first measuring force (F) e1 ) Pull the adhesive component and use the second measuring force (F) e2 When the adhesive component is pulled, the first part of the adhesive component can be adhered to a portion of the main surface of the substrate by the adhesive strength of the adhesive component. A portion of the adhesive component adjacent to the first part can be bent, so that the second part of the adhesive component is fixed to the first fixing part of the measuring device, and the first fixing part can be fixed with a first measuring force (F). e1 ) or second measuring force (F e2 Pull the second part of the adhesive component.

[0016] In the implementation method, an evaluation time (t) is set. e The method may include: adhering a first portion of the adhesive member to a substrate; fixing a second portion of the adhesive member to a first fixing portion of the measuring device; and fixing the substrate to a second fixing portion of the measuring device; using a reference force (F) S The second part of the adhesive component, which is fixed by the first fixing part of the measuring device, is pulled; the first part of the adhesive component is measured according to time (t). n The second distance (d) separated from the substrate n ); Determine the second distance (d) n The change (Δd) of ) with time (t) n The rate of change (Δt) is 10 -5 Or a shorter time interval; and the evaluation time (t) is set based on this time interval. e ).

[0017] In the implementation method, the reference force (F) S It can be 10% of the adhesive strength of the bonded components. -1 .

[0018] In the implementation method, the reference force (F) S It can be equal to the adhesive strength of the bonded component.

[0019] In the implementation method, when using the reference force (F) S When the second part of the adhesive component, which is fixed by the first fixing part of the measuring device, is pulled, the pulling force can be increased from 0 to the reference force (F). S ), and then the reference force (F) S It can remain constant.

[0020] In one embodiment, a first portion of the adhesive member can be adhered to a portion of the main surface of the substrate by the adhesive strength of the adhesive member, and a portion of the adhesive member adjacent to the first portion can be bent such that a second portion of the adhesive member is fixed to a first fixing portion of the measuring device. The first fixing portion can be fixed with a reference force (F). S Pull the second part of the adhesive component.

[0021] In an implementation, the method may further include setting an evaluation time (t). e Before proceeding, measure the bond strength of the bonded components.

[0022] In one embodiment, fixing the substrate and the adhesive member to the measuring device may include: adhering a first portion of the adhesive member to the substrate, fixing a second portion of the adhesive member to a first fixing portion of the measuring device, and fixing the substrate to a second fixing portion of the measuring device.

[0023] In one embodiment, the first part of the adhesive member can be adhered to a portion of the main surface of the substrate by the adhesive strength of the adhesive member, and a portion of the adhesive member adjacent to the first part can be bent such that the second part of the adhesive member is fixed to the first fixing part of the measuring device.

[0024] In this embodiment, the second fixing part of the measuring device can be fixed to the measuring device, and the second fixing part of the measuring device fixes the substrate. The first fixing part of the measuring device can pull the second part of the adhesive member in a direction parallel to the main surface of the substrate.

[0025] In the implementation, when the distance by which the first part of the adhesive member separates from the substrate is less than or equal to a preset distance (d) t When the first part of the adhesive member separates from the substrate by a distance exceeding a preset distance (d), the adhesive member remains in a state where the first part of the adhesive member can adhere to the substrate. t When ), the deformation of the first part of the bonded component can begin.

[0026] In the method for measuring adhesive strength according to an embodiment of the present invention, an evaluation time can be set, and the distance by which a first portion of the adhesive member is statically separated from the substrate during the evaluation time can be measured, thereby determining a reference measuring force of the adhesive member. The reference measuring force may include information about the adhesive member's ability to retain adhesion and information about the force itself. Therefore, by using the method for measuring adhesive strength, appropriate adhesive members can be selected based on their application, structural constraints, and design characteristics, and adhesive failure of adhesive members included in display devices can be reduced. Attached Figure Description

[0027] The embodiments can be understood in more detail from the following description taken in conjunction with the accompanying drawings, wherein:

[0028] Figures 1 to 17 A diagram illustrating a method for measuring adhesive strength according to an embodiment of the present invention; and

[0029] Figure 18 and Figure 19 This is a flowchart illustrating a method for measuring adhesive strength according to an embodiment of the present invention. Detailed Implementation

[0030] What will be understood is that when an element is referred to as being "on" another element, it can be directly on said other element, or there can be an intermediate element between them. Conversely, when an element is referred to as being "directly on another element," there is no intermediate element.

[0031] It will be understood that although the terms “first,” “second,” “third,” etc., may be used herein to describe various elements, components, regions, layers, and / or parts, these elements, components, regions, layers, and / or parts should not be limited by these terms. These terms are used only to distinguish one element, component, region, layer, or part from another. Therefore, without departing from the teachings herein, “first element,” “first part,” “first region,” “first layer,” or “first section” discussed below may be referred to as a second element, second part, second region, second layer, or second section.

[0032] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms “a(a)”, “an”, and “the” are intended to include the plural forms, including “at least one”, unless the context clearly indicates otherwise. “At least one” should not be construed as limiting “a(a)” or “an”. “Or” means “and / or”. As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items. It will also be understood that the terms “comprise” and / or “comprising” or “include” and / or “including”, when used in this specification, indicate the presence of the stated features, areas, integrals, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, areas, integrals, steps, operations, elements, components, and / or groups thereof.

[0033] The method for measuring adhesive strength according to an embodiment of the present invention will be described in detail below with reference to the accompanying drawings. In the drawings, the same or similar reference numerals denote the same or similar elements.

[0034] Figures 1 to 17 This is a diagram illustrating a method for measuring adhesive strength according to an embodiment of the present invention, and Figure 18 and Figure 19 This is a flowchart illustrating a method for measuring adhesive strength according to an embodiment of the present invention. For example, Figure 18 This corresponds to the flowchart for setting the evaluation time, and Figure 19 This is a flowchart corresponding to determining the benchmark measurement force based on the evaluation time.

[0035] refer to Figure 1 , Figure 2 and Figure 18 , Figure 1 This is a front view showing an embodiment of the substrate 110 and the adhesive member 130, and Figure 2 It is shown Figure 1 Left side view of the substrate 110 and the adhesive member 130.

[0036] The adhesive strength of the adhesive member 130 can be measured (S510). The adhesive strength of the adhesive member 130 can be measured using a peel strength scheme that measures the average force applied during the peel interval, a probe adhesive scheme that measures the maximum force applied per unit area during peeling, a shear stress scheme that measures shear strain, or a holding force scheme that measures the degree to which a predetermined weight is withstood within a predetermined time. In an embodiment, an adhesive film having an adhesive strength of approximately 5000 gf / 25 mm can be used as the adhesive member 130. For example, adhesive strength means that the force required to peel an adhesive film with a width of 25 mm is 5000 gf. In some embodiments, an adhesive film having an adhesive strength different from the above-described adhesive strength can be used as the adhesive member 130. For example, the adhesive member 130 may include a base film, a first adhesive and a second adhesive, a first release film and a second release film, etc. In this configuration, the base film may include polyethylene terephthalate (“PET”) film, each of the first adhesive and the second adhesive may include an urethane-based adhesive, an acrylic-based adhesive, and a silicone-based adhesive, and each of the first release film and the second release film may include a PET film. Furthermore, the first adhesive and the second adhesive may be disposed on the top and bottom surfaces of the base film, respectively, and the first release film and the second release film may be disposed on the first adhesive and the second adhesive to cover them, respectively. In an embodiment, the adhesive member 130 may include a first portion 131 and a second portion 132. For example, the first portion 131 and the second portion 132 of the adhesive member 130 may face each other.

[0037] The first portion 131 of the adhesive member 130 can be adhered to the substrate 110 (S520). For example, the first release film of the adhesive member 130 can be removed, and the first adhesive in the first portion 131 of the adhesive member 130 can come into contact with the substrate 110.

[0038] The first portion 131 of the adhesive member 130 can be adhered to the top surface of the substrate 110 by the adhesive strength of the adhesive member 130 (i.e., as shown in the figure). Figure 2 As shown, a portion of the main surface (of which the first portion 131 is attached) and a portion of the adhesive member 130 adjacent to the first portion 131 can be bent such that the adhesive member 130 can have a "J" shape. In other words, the substrate 110 and the adhesive member 130 can correspond to a 180-degree (°) peel sampling. In some embodiments, it can be based on the measuring device 300 (see...) Figure 3 and Figure 4 The position of the first fixing part 310 is configured by 90° peel sampling to arrange the substrate 110 and the adhesive member 130. For example, when the angle between the first part 131 and the second part 132 is as follows: Figure 2 When the angle is 180°, it is a 180° peel sampling, and when the angle between the first portion 131 and the second portion 132 is 90° (not shown), it is a 90° peel sampling. In other embodiments, the substrate 110 and the adhesive member 130 may be configured by area contact sampling (such as a flat punch scheme or a spherical probe scheme) depending on the type of measuring device 300. The substrate 110 may include metal, such as stainless steel (“SUS”), metal alloy, etc.

[0039] refer to Figure 3 , Figure 4 and Figure 18 , Figure 3 This is a front view showing an embodiment of the substrate 110, the adhesive member 130, and the measuring device 300, and Figure 4 It is shown Figure 3 Left side view of the substrate 110, adhesive member 130 and measuring device 300.

[0040] The measuring device 300 may include a first fixing part 310, a second fixing part 320, and a main body 330. The main body 330 may extend in a first direction D1 and a second direction D2 orthogonal to the first direction D1, and the second fixing part 320 may be located on the top surface of the main body 330. Furthermore, the main body 330 may extend in a third direction D3 perpendicular to the first direction D1 and the second direction D2 to connect to the first fixing part 310. In this case, the second fixing part 320 may be fixed to the top surface of the main body 330, and the first fixing part 310 may pull an object along the third direction D3 (e.g., a direction parallel to the top surface of the substrate 110). For example, the measuring device 300 may be a device configured to measure tension.

[0041] The second portion 132 of the adhesive member 130 can be fixed to the first fixing portion 310 of the measuring device 300, and the substrate 110 can be fixed to the second fixing portion 320 of the measuring device 300 (S530). For example, the portion of the adhesive member 130 adjacent to the first portion 131 can be bent, so that the second portion 132 of the adhesive member 130 can be fixed to the first fixing portion 310 of the measuring device 300. In addition, the first side of the substrate 110 (i.e., Figure 3 and Figure 4 The lower side of the substrate 110 is fixed to the second fixing part 320, and the second side of the substrate 110 (i.e., Figure 3 and Figure 4 The upper side of the middle part can be adjacent to the first fixing part 310.

[0042] Figure 5 This is a front view showing the substrate 110, the adhesive member 130, and the measuring device 300 to illustrate the reference force F applied to the adhesive member 130. S ,as well as Figure 6 It is shown Figure 5 A left-side view of the substrate 110, the adhesive member 130, and the measuring device 300. Furthermore, Figure 7 The reference force F S (gf) is a graph of time (s). Reference force F S It is a measuring force used to pull the second part 132 of the adhesive member 130 fixed in the first fixing part 310 of the measuring device 300. Figure 8 The measuring device 300 measures the time t. n The change Δt measures the second distance d n The curve obtained by the change Δd.

[0043] The reference force F can be used S The second part 132 (S540) of the adhesive member 130, which is fixed by the first fixing part 310 of the measuring device 300, is pulled. In the embodiment, the reference force FS It can be about 10% of the adhesive strength of the adhesive member 130 applied to the substrate 110. -1 For example, the adhesive strength of adhesive components 130, such as protective films, optically clear adhesives (“OCA”), pressure-sensitive adhesives (“PSA”), optically clear resins (“OCR”), anisotropic conductive films (“ACF”), and double-sided fixing tapes typically included in display devices, can be 5000 gf / 25 mm or less, and adhesive components 130 (or bonding components) with an adhesive strength of 5000 gf / 25 mm or less can have a Young's modulus of 1 gigapascal (GPa) or less at room temperature during rheological evaluation. In this case, linear viscoelasticity at 1 / 10 of the adhesive strength can be measured. Therefore, in general, the reference force F S Limited to 10% of the adhesive strength of the adhesive member 130 -1 Horizontal. Therefore, since the adhesive strength of the adhesive component 130 is approximately 5000 gf / 25 mm, the reference force F can be... S Set to 500gf / 25mm.

[0044] In other implementations, the reference force F can be... S The reference force F is set to be equal to the adhesive strength of the adhesive member 130. For example, the reference force F can be set according to the design characteristics of the display device to which the adhesive member 130 is applied. S The adhesive strength is limited to the adhesive strength of the adhesive component 130.

[0045] like Figure 7 As shown, when using the reference force F S When the second part 132 of the adhesive member 130, which is fixed to the first fixing part 310 of the measuring device 300, is pulled, the pulling force can increase from 0 to the reference force F. S (For example, approximately 500gf / 25mm), and the reference force F S It can remain constant after the predetermined time.

[0046] like Figure 8 As shown, when using a reference force F S While pulling the second part 132 of the adhesive member 130, which is fixed to the first fixing part 310 of the measuring device 300, the measuring device 300 can measure the first part 131 of the adhesive member 130 according to time t. n The second distance d separated from the substrate 110 n (S550). Furthermore, the measuring device 300 can determine the second distance d therein. n The change Δd with time t n The ratio of the change Δt is 10. -5 Or a shorter time interval (S560). In other words,Figure 8 The slope of the curve shown can be determined by the following mathematical formula 1.

[0047] [Mathematical Formula 1]

[0048]

[0049] The measuring device 300 can determine a fourth interval (t3-t4), which is a time interval in which the tilt is 0.00001. Therefore, the time interval in which the tilt is 0.00001 or less can be a first interval (0-t1), a second interval (t1-t2), and a third interval (t2-t3). In this case, the first interval (0-t1) can be defined as a substrate-affected interval, the second interval (t1-t2) can be defined as an unstable adhesive strength interval, the third interval (t2-t3) can be defined as an adhesive strength convergence interval, and the fourth interval (t3-t4) can be defined as a stable adhesive strength interval. Alternatively, the first interval (0-t1), the second interval (t1-t2), and the third interval (t2-t3) can be defined as unstable adhesive strength intervals, and the fourth interval (t3-t4) can be defined as a stable adhesive strength interval. In the implementation, the time interval (0-t3) (which is the sum of the first interval (0-t1), the second interval (t1-t2), and the third interval (t2-t3) where the slope is 0.00001 or less) can be set as the evaluation time t. e (S570). For example, when using an adhesive member 130 with an adhesive strength of approximately 5000 gf / 25 mm, the reference force F can be... S Set to 500gf / 25mm, and the evaluation time t can be set. e Set to 180 seconds.

[0050] In the experiment, when the distance change per second was 0.00001, the distance change after 24 hours was approximately 0.864 mm. Since the distance change Δd was less than 1 mm (a standard used to determine defects in adhesive components included in display devices), the tilt angle was set to 10. -5 However, the criteria used to determine defects can vary depending on the design characteristics of the display device to which the adhesive component is applied. In this case, the tilt angle can be less than or greater than 0.00001.

[0051] As mentioned above, in measurement Figures 1 to 8 In the method for assessing adhesive strength shown, an evaluation time t can be set. e .

[0052] refer to Figure 9 , Figure 10 and Figure 19, Figure 9 This is a front view showing an embodiment of the substrate 110, adhesive member 130, and measuring device 300, illustrating the steps in the method for determining the reference measuring force. Figure 10 It is shown Figure 9 Left side view of the substrate 110, adhesive member 130 and measuring device 300.

[0053] Set the evaluation time t e Then, the substrate 110 and the adhesive member 130 can be fixed to the measuring device 300 (S610). In other words, the first portion 131 of the adhesive member 130 can be adhered to the substrate 110, the second portion 132 of the adhesive member 130 can be fixed to the first fixing portion 310 of the measuring device 300, and the substrate 110 can be fixed to the second fixing portion 320 of the measuring device 300. For example, the first portion 131 of the adhesive member 130 can be adhered to the substrate 110 such that the first portion 131 of the adhesive member 130 can be adhered to a portion of the top surface of the substrate 110 by the adhesive strength of the adhesive member 130, and the portion of the adhesive member 130 adjacent to the first portion 131 can be bent so that the second portion 132 of the adhesive member 130 can be fixed to the first fixing portion 310 of the measuring device 300. In addition, the second fixing portion 320 of the measuring device 300 can be fixed to the body 330 of the measuring device 300, and the second fixing portion 320 can fix the substrate 110.

[0054] Figure 11 This is a front view showing the substrate 110, the adhesive member 130, and the measuring device 300 to illustrate another step in the method for determining the reference measuring force, and Figure 12 It is shown Figure 11 A left-side view of the substrate 110, the adhesive member 130, and the measuring device 300. Furthermore, Figure 17 This is a graph of the separation distance (mm) versus the measuring force (gf). The first measuring force is F. e1 Up to the nth measured force F en The evaluation time t is reached by pulling the adhesive component 130 and fixing the second part 132, which is fixed by the first fixing part 310 of the measuring device 300. e The force obtained is the measured force.

[0055] The first measuring force F can be used e1 (For example, static) pulling the adhesive member 130 fixed to the measuring device 300 for the evaluation time t e (For example, 180 seconds) (S620). In the implementation, the first measuring force F e1 It can be approximately 100gf / 25mm. For example, when using the first measuring force F... e1Pull the adhesive component 130 fixed to the measuring device 300 to the evaluation time t e (For example, at 180 seconds) the tension can increase from 0 to the first measured force F. e1 (e.g., 100gf / 25mm), and the first measuring force F e1 It can be evaluated at time t e It remains constant during the period.

[0056] Using the first measuring force F e1 Pull the adhesive component 130 fixed to the measuring device 300 to the evaluation time t e (For example, 180 seconds) while the measuring device 300 can measure the distance by which the first portion 131 of the adhesive member 130 separates from the substrate 110 (S630). Figure 17 This shows that when the first measuring force F is used... e1 The distance by which the first portion 131 of the adhesive member 130 separates from the substrate 110 when pulled.

[0057] After the measuring device 300 measures the distance at which the first portion 131 of the adhesive member 130 separates from the substrate 110, the measuring device 300 can compare the measured distance at which the first portion 131 of the adhesive member 130 separates from the substrate 110 with a preset distance d. t Comparison (S640).

[0058] As mentioned above, experimentally, when the standard used to determine defects in adhesive components included in a display device is 1 mm, for example, a preset distance d can be used. t The setting is 1mm. However, the criteria used to determine defects can vary depending on the application of the bonded component, structural constraints, design characteristics, etc. In this case, the preset distance d is... t It can be less than or greater than 1 mm.

[0059] Figure 13 This is a front view showing the substrate 110, the adhesive member 130, and the measuring device 300 to illustrate another step in the method for determining the reference measuring force, and Figure 14 It is shown Figure 13 Left side view of the substrate 110, adhesive member 130 and measuring device 300.

[0060] The first measuring force F was measured. e1After separating the first portion 131 of the adhesive member 130 from the substrate 110 by a certain distance, the substrate 110 and the adhesive member 130 can be reattached to the measuring device 300 (S650). In other words, the first portion 131 of the adhesive member 130 can be adhered to the substrate 110, the second portion 132 of the adhesive member 130 can be fixed to the first fixing portion 310 of the measuring device 300, and the substrate 110 can be fixed to the second fixing portion 320 of the measuring device 300. For example, the first portion 131 of the adhesive member 130 can be adhered to the substrate 110 such that the first portion 131 of the adhesive member 130 can be adhered to a portion of the top surface of the substrate 110 by the adhesive strength of the adhesive member 130, and the portion of the adhesive member 130 adjacent to the first portion 131 can be bent so that the second portion 132 of the adhesive member 130 can be fixed to the first fixing portion 310 of the measuring device 300. In addition, the second fixing part 320 of the measuring device 300 can be fixed to the main body 330 of the measuring device 300, and the second fixing part 320 can fix the substrate 110.

[0061] Figure 15 This is a front view showing the substrate 110, the adhesive member 130, and the measuring device 300 to illustrate another step in the method for determining the reference measuring force, and Figure 16 It is shown Figure 15 Left side view of the substrate 110, adhesive member 130 and measuring device 300.

[0062] The second measuring force F can be used e2 (For example, static) pulling the adhesive member 130 fixed to the measuring device 300 for the evaluation time t e (For example, 180 seconds) (S660), where the second measuring force F e2 It is by measuring the first force F e1 This is achieved by increasing a preset amount (e.g., 100gf / 25mm). In the embodiment, the second measuring force F e2 It can be approximately 200gf / 25mm. For example, when using the second measuring force F... e2 Pull the adhesive component 130 fixed to the measuring device 300 to the evaluation time t e (For example, at 180 seconds), the tension can increase from 0 to the second measured force F. e2 (e.g., 200gf / 25mm), and the second measuring force F e2 It can be evaluated at time t e It remains constant during the period.

[0063] Using the second measuring force F e2 Pull the adhesive component 130 fixed to the measuring device 300 to the evaluation time t e(For example, 180 seconds) while the measuring device 300 can measure the distance by which the first portion 131 of the adhesive member 130 separates from the substrate 110 (S670). Figure 17 This shows that when using the second measuring force F e2 The distance by which the first portion 131 of the adhesive member 130 separates from the substrate 110 when pulled.

[0064] After the measuring device 300 measures the distance at which the first portion 131 of the adhesive member 130 separates from the substrate 110, the measuring device 300 can compare the measured distance at which the first portion 131 of the adhesive member 130 separates from the substrate 110 with a preset distance d. t Comparison (S680).

[0065] refer to Figure 17 The third measuring force F e3 Fourth measuring force F e4 ... and the nth measuring force F en It can be measured in the same way as described above. For example, the third measuring force F e3 It can be approximately 300gf / 25mm, the fourth measuring force F e4 It can be approximately 400gf / 25mm, and the nth measuring force F en It can be approximately 100×n gf / 25mm.

[0066] In the implementation method, such as Figure 17 As shown, it can be determined that the distance by which the first portion 131 of the adhesive member 130 separates from the substrate 110 is equal to a preset distance d. t The reference static F es (S690). For example, the force F measured from the first measuring force can be... e1 To the reference measurement force F es The interval is defined as the adhesion force holding interval, which can be measured from the reference force F. es The force F measured at the (n-1)th time en-1 The interval is defined as the adhesion force enhancement interval or the sagging generation interval, and the force F can be measured from the (n-1)th force. en-1 up to the nth measured force F en The interval is defined as the peeling interval. Alternatively, the force F measured from the first measuring force can be... e1 To the reference measurement force F es The interval is defined as the adhesion force holding interval, and the force F can be measured from the reference force. es up to the nth measured force F en The interval is defined as the interval at which the first portion 131 of the adhesive member 130 begins to deform. In an embodiment, a first measuring force F is used. e1 The process of pulling the adhesive component 130 until the nth measuring force F is used enThe process of pulling the adhesive component 130 can be performed independently.

[0067] In other embodiments, depending on the type of adhesive member 130, the first measuring force F e1 It can be less than 100gf / 25mm, and because the preset amount is relatively small, the first measuring force F e1 With the second measuring force F e2 The difference between them can be relatively small. In this case, the measuring force can be measured accurately.

[0068] As mentioned above, in Figures 9 to 17 as well as Figure 19 In the method for measuring adhesive strength shown, a reference measuring force F can be determined. es .

[0069] Conventional methods for measuring the adhesive strength of bonded components involve measurements relative to simple forces, such as peel strength, probe adhesion, shear stress, and holding force. Typically, the bonded component is applied to a display device using these measurement methods. However, even when a bonded component selected using these methods is applied to a display device, defects may occur, such as residues (e.g., dead material) remaining on the adhesive surface or the inability to maintain adhesive strength when bent or repeatedly folded. In other words, defects may arise in the bonded component selected using these measurement methods, depending on its application, structural constraints, design characteristics, etc.

[0070] In the method for measuring adhesive strength according to an embodiment of the present invention, an evaluation time t can be set. e And it can be measured at the evaluation time t e The distance by which the first portion 131 of the adhesive member 130 is separated from the substrate 110 by internal static force allows the determination of the reference measuring force F of the adhesive member 130. es Reference measuring force F es Information may include the adhesive strength retention capability of the adhesive member 130 and information about the force. Therefore, by using a method of measuring adhesive strength, an appropriate adhesive member 130 can be selected based on the application, structural constraints, and design characteristics of the adhesive member, and adhesive failure of the adhesive member 130 included in a display device can be reduced.

[0071] Experimental Example: Evaluating Bond Strength and Benchmark Force F Based on Adhesive Components es

[0072] Table 1 below describes the lamination structure of each of the adhesive components A, B, C, D, E, and F. For example, adhesive component A may have a lamination structure such as isolation liner (PET 50 μm) / adhesive (12.5 μm) / PET (25 μm) / adhesive (12.5 μm) / isolation liner (PET 50 μm) and can be used as an FPC fixing tape in a display device. Adhesive component B may have a lamination structure such as isolation liner (PET 50 μm) / adhesive (27.5 μm) / PET (25 μm) / adhesive (27.5 μm) / isolation liner (PET 23 μm) and can be used as a double-sided tape in a display device. Adhesive component C may have a laminated structure such as isolation liner (PET 50μm) / adhesive (25μm) / PET (50μm) / adhesive (25μm) / isolation liner (PET 23μm) and can be used as double-sided tape in a display device. Adhesive component D may have a laminated structure such as isolation liner / adhesive / PET / adhesive / isolation liner and can be used as FPC fixing tape in a display device. Adhesive component E may have a laminated structure such as isolation liner / adhesive (22μm) / PET (6μm) / adhesive (22μm) / isolation liner and can be used as double-sided tape in a display device. Adhesive component F may have a laminated structure such as isolation liner (PET 50μm) / adhesive (25μm) / isolation liner (PET 25μm) and can be used as double-sided digitizer tape in a display device.

[0073] The peel strength of each of the bonded components A, B, C, D, E and F was measured and is shown in Table 1 below.

[0074] When the evaluation time t e Set to measure the first measuring force F of each of the bonded components A, B, C, D, E, and F after 3 minutes. e1 Up to the nth measured force F en This causes the measuring force to increase by 100 gf / 25 mm within 3 minutes. Based on the first measuring force F e1 Up to the nth measured force F en The reference measured force F for each adhesive component A, B, C, D, E, and F. es (Static) is shown in Table 1 below.

[0075] [Table 1]

[0076]

[0077]

[0078] As shown in Table 1, the peel strength and reference measurement force F of each of the bonded components A, B, C, and F are... es They were measured to be at similar levels. However, the peel strength and the benchmark measured force F of each of the bonded components D and E were different. es Significant differences were observed. In the case of bonded component D, the measured peel strength was approximately 1474.9 gf / 25 mm, and the measured static force (which is the reference measured force F) was also significant. es The peel strength was approximately 300 gf / 3 minutes. In other words, the peel strength and static strength of adhesive component D showed a significant difference, and lift failure occurred when adhesive component D was actually applied to the display device as an FPC fixing tape. Furthermore, residue remained when adhesive component D was removed from the substrate. Therefore, when adhesive components selected based solely on simple force information (such as peel strength) are applied to the display device, the likelihood of defects is high. Therefore, by selecting adhesive components using static strength information that includes information about adhesive retention capacity, the likelihood of defects in adhesive components included in the display device can be significantly reduced.

[0079] This invention can be applied to methods for measuring adhesive strength, which is used to select adhesive components for various electronic devices, including display devices. For example, this invention can be applied to vehicle display devices, marine display devices, aircraft display devices, portable communication devices, display devices for display or information transmission, medical display devices, etc.

[0080] The foregoing is a description of embodiments and should not be construed as limiting them. Although several embodiments have been described, those skilled in the art will readily understand that many modifications may be made to the embodiments without substantially departing from the novel teachings and advantages of the inventive concept. Therefore, all such modifications are intended to be included within the scope of the inventive concept as defined in the claims. It will thus be understood that the foregoing is a description of various embodiments and should not be construed as limiting to the specific embodiments disclosed, and modifications to the disclosed embodiments and other embodiments are intended to be included within the scope of the appended claims.

Claims

1. A method for measuring adhesive strength, the method comprising: Set an evaluation timeframe; Fix the substrate and adhesive components to the measuring device; The adhesive component fixed to the measuring device is pulled by a first measuring force for the duration of the evaluation. The adhesive member fixed to the measuring device is pulled by a second measuring force for the evaluation time, wherein the second measuring force is obtained by increasing the first measuring force by a preset amount; and A reference measuring force is determined, which is the static force applied to the adhesive member when the distance by which the first part of the adhesive member separates from the substrate is equal to a preset distance. The evaluation time is set as follows: The first portion of the adhesive member is adhered to the substrate; The second part of the adhesive member is fixed to the first fixing part of the measuring device, and the substrate is fixed to the second fixing part of the measuring device; The second part of the adhesive member, which is fixed by the first fixing part of the measuring device, is pulled by a reference force; Measure a second distance from which the first portion of the adhesive member separates from the substrate over time; The ratio of the change in the second distance to the change in time is determined to be 10. -5 Or a shorter time interval; and The evaluation time is set based on the aforementioned time interval.

2. The method according to claim 1, further comprising: After the adhesive member fixed to the measuring device is pulled with the first measuring force for the evaluation time, the distance by which the first portion of the adhesive member separates from the substrate is measured. as well as After measuring the distance at which the first portion of the adhesive member separates from the substrate, the distance at which the first portion of the adhesive member separates from the substrate is compared with the preset distance.

3. The method according to claim 1, wherein, When the adhesive member fixed to the measuring device is pulled with the first measuring force for the evaluation time, the pulling force increases from 0 to the first measuring force, and then the first measuring force remains constant during the evaluation time.

4. The method according to claim 1, further comprising: Before the evaluation time is reached, the substrate and the adhesive member are re-fixed to the measuring device by pulling the adhesive member fixed to the measuring device with the second measuring force obtained by increasing the first measuring force by the preset amount; After the evaluation time is reached, the adhesive member fixed to the measuring device is pulled by a second measuring force obtained by increasing the first measuring force by the preset amount for a period of time, and the distance by which the first part of the adhesive member separates from the substrate is measured; as well as After measuring the distance at which the first portion of the adhesive member separates from the substrate, the distance at which the first portion of the adhesive member separates from the substrate is compared with the preset distance.

5. The method according to claim 1, wherein, When the adhesive member fixed to the measuring device is pulled with the second measuring force for the evaluation time, the pulling force increases from 0 to the second measuring force, and then the second measuring force remains constant during the evaluation time.

6. The method according to claim 1, wherein, Pulling the adhesive member with the first measuring force and pulling the adhesive member with the second measuring force are performed independently.

7. The method according to claim 1, wherein, When the adhesive member is pulled by the first measuring force and the adhesive member is pulled by the second measuring force, the first part of the adhesive member is adhered to a portion of the main surface of the substrate by the adhesive strength of the adhesive member, and a portion of the adhesive member adjacent to the first part is bent such that the second part of the adhesive member is fixed to the first fixing part of the measuring device, and the first fixing part pulls the second part of the adhesive member by the first measuring force or the second measuring force.

8. The method according to claim 1, wherein, The reference force is 10% of the adhesive strength of the adhesive component. -1 .

9. The method according to claim 1, wherein, The reference force is equal to the adhesive strength of the adhesive component.

10. The method according to claim 1, wherein, When the second part of the adhesive member, which is fixed by the first fixing part of the measuring device, is pulled with the reference force, the pulling force increases from 0 to the reference force, and then the reference force remains constant.

11. The method according to claim 1, wherein, The first portion of the adhesive member is adhered to a portion of the main surface of the substrate by the adhesive strength of the adhesive member. A portion of the adhesive member adjacent to the first part is bent, such that the second part of the adhesive member is fixed to the first fixing part of the measuring device, and The first fixing part pulls the second part of the adhesive member with the reference force.

12. The method according to claim 1, further comprising: Before setting the evaluation time, the adhesive strength of the bonded component is measured.

13. The method according to claim 1, wherein, Fixing the substrate and the adhesive member to the measuring device includes: Adhere the first portion of the adhesive member to the substrate; and The second part of the adhesive member is fixed to the first fixing part of the measuring device, and the substrate is fixed to the second fixing part of the measuring device; Wherein, the first portion of the adhesive member is adhered to a portion of the main surface of the substrate by the adhesive strength of the adhesive member, and A portion of the adhesive member adjacent to the first part is bent, such that the second part of the adhesive member is fixed to the first fixing part of the measuring device, and The second fixing part of the measuring device is fixed to the measuring device. The second fixing part of the measuring device fixes the substrate, and The first fixing part of the measuring device pulls the second part of the adhesive member in a direction parallel to the main surface of the substrate.

14. The method according to claim 1, wherein, When the distance by which the first portion of the adhesive member separates from the substrate is less than or equal to the preset distance, the first portion of the adhesive member remains adhered to the substrate. When the distance by which the first portion of the adhesive member separates from the substrate exceeds the preset distance, the first portion of the adhesive member begins to deform.

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