Method for testing rheological properties of adhesive films

Abstract

The application discloses a kind of rheological property test methods of adhesive film.The rheological property test method includes;S1, provide multiple adhesive film components;S2, remove the film release film of one of the adhesive film components, and remove the film release film of the adhesive film component is fixed to workbench, bottom film release film is in contact with workbench;S3, remove the film release film and bottom film release film of the remaining multiple adhesive film components in turn, and multiple adhesive film bodies are laminated and bonded together to reach set thickness, wherein the last adhesive film component retains bottom film release film, so that multiple adhesive film bodies are located between two bottom film release films, and two bottom film release films and multiple adhesive film layers between two bottom film release films are to be tested;S4, remove the tested piece from workbench, and keep the tested piece at a set temperature for a set time to eliminate the stress of the tested piece;S5, test the rheological property of the tested piece after stress relief.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of performance testing, more particularly, to a rheological property testing method of adhesive film. BACKGROUND

[0002] Composite materials are increasingly widely used in acoustic diaphragms. Such materials usually need adhesive films to bond multiple film layers together. The adhesive film not only plays a bonding role, but also provides damping performance for the acoustic diaphragm, thereby optimizing the bass effect of the acoustic diaphragm and improving the shear resistance of the acoustic diaphragm. Therefore, the characterization of the rheological property parameters of the adhesive film, such as the storage modulus, loss modulus, loss factor, creep, stress relaxation, etc. under shear or tensile mode, is crucial. The adhesive film is very thin and has very small strength, usually in microns, and under this condition, the adhesive film cannot be directly made into a standard strip-shaped sample for rheological property testing.

[0003] Therefore, there is a need to provide a new technical solution to solve the above technical problems. SUMMARY

[0004] An object of the present application is to provide a new technical solution of a rheological property testing method of adhesive film.

[0005] According to a first aspect of the present application, a rheological property testing method of adhesive film is provided. The adhesive film assembly comprises a bottom film release film, a top film release film and an adhesive film body attached between the bottom film release film and the top film release film, the peeling strength of the bottom film release film is greater than that of the top film release film; the testing method comprises:

[0006] S1, providing a plurality of adhesive film assemblies;

[0007] S2, removing the top film release film of one of the adhesive film assemblies, and fixing the adhesive film assembly with the top film release film removed to a workbench, the bottom film release film being in contact with the workbench;

[0008] S3, sequentially removing the top film release film and the bottom film release film of the remaining plurality of adhesive film assemblies, and laminating and bonding the plurality of adhesive film bodies together to achieve a set thickness, wherein the last adhesive film assembly retains the bottom film release film, so that the plurality of adhesive film bodies are located between two bottom film release films, and the two bottom film release films and the plurality of adhesive film bodies located between the two bottom film release films are the test piece;

[0009] S4, removing the test piece from the workbench, and keeping the test piece at a set temperature for a set time to eliminate the stress of the test piece;

[0010] S5, testing the rheological property of the test piece after stress elimination.

[0011] Optionally, in step S1, the edges of the adhesive film assembly with the release film removed are fixed to the workbench by adhesive tape.

[0012] Optionally, in step S2, first, the release film of each adhesive film is removed;

[0013] Then, the adhesive film bodies are bonded together with the adhesive film bodies on the workbench;

[0014] Finally, the release film of the bottom film is removed.

[0015] Optionally, when bonding the two adhesive film bodies, the bonding is gradually performed from the same side of the two adhesive film bodies, and the release film of the bottom film is scraped from one side to the other side by a spatula.

[0016] Optionally, before step S1, the method further comprises cutting the plurality of adhesive film assemblies into oblong test pieces, the oblong test pieces having a width of 5-8 cm and a length of 10 cm.

[0017] Optionally, the set thickness is 0.5-1 mm.

[0018] Optionally, in step S5, the method further comprises cutting the test piece to be tested into a set size and shape, and removing the two release films of the bottom film.

[0019] Optionally, in step S5, the method comprises shear mode testing and tensile mode testing.

[0020] Optionally, in step S4, the set temperature is 30-50°C, and the set time is 2-4 hours.

[0021] Optionally, in step S4, the test piece to be tested is placed into a thermostat.

[0022] In the embodiments of the present disclosure, the plurality of adhesive film bodies are laminated and bonded together to form a test piece with a set thickness to meet the thickness requirement of the test equipment for the test piece. The performance of the adhesive film body is characterized by measuring the rheological properties of the test piece with the set thickness. The method can effectively test and evaluate the rheological properties of the adhesive film body.

[0023] In addition, the plurality of adhesive film bodies are prone to residual stress when laminated and bonded. By keeping the plurality of adhesive film bodies with the release film of the bottom film attached to both sides at a set temperature for a set time, the stress of the test piece can be effectively eliminated. This makes the rheological property test of the plurality of adhesive film bodies more accurate, and the consistency of the test results good.

[0024] Other features and advantages of the present disclosure will become apparent from the following detailed description of exemplary embodiments thereof, with reference to the accompanying drawings. Attached Figure Description

[0025] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of the invention and, together with their description, serve to explain the principles of the invention.

[0026] Figure 1 This is a flowchart of a method for testing the rheological properties of an adhesive film according to an embodiment of the present disclosure.

[0027] Figure 2 The curves showing the changes in storage modulus, loss modulus, and loss factor with temperature for the shear mode test of the multilayer film body according to embodiments of this disclosure.

[0028] Figure 3 This is a TTS (Time-Temperature Transition) curve under shear mode of the multilayer film body according to an embodiment of this disclosure.

[0029] Figure 4 The curves showing the changes in storage modulus and loss modulus with temperature for the tensile mode test of the multilayer film body according to the embodiments of this disclosure.

[0030] Figure 5 The curves show the changes in relaxation modulus and strain recovery rate over time in the tensile mode of the multilayer film body according to an embodiment of this disclosure. Detailed Implementation

[0031] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention.

[0032] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0033] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0034] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0035] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0036] According to one embodiment of this disclosure, a method for testing the rheological properties of an adhesive film is provided.

[0037] The adhesive film assembly comprises a bottom release film, a top release film, and an adhesive film body attached between the bottom release film and the top release film. The bottom release film has a peel strength greater than that of the top release film. As shown in Figure 1 The test method comprises the following steps:

[0038] S1. Providing a plurality of adhesive film assemblies;

[0039] S2. Removing the top release film of one of the adhesive film assemblies, and fixing the adhesive film assembly with the top release film removed to a workbench, with the bottom release film in contact with the workbench;

[0040] S3. Removing the top release film and the bottom release film of the remaining adhesive film assemblies in sequence, and laminating the plurality of adhesive film bodies together to achieve a set thickness. The last adhesive film assembly retains the bottom release film, so that the plurality of adhesive film bodies are located between two bottom release films. The two bottom release films and the plurality of adhesive film bodies located therebetween constitute a test piece;

[0041] S4. Removing the test piece from the workbench, and maintaining the test piece at a set temperature for a set time to eliminate the stress of the test piece;

[0042] S5. Testing the rheological properties of the test piece after the stress is eliminated.

[0043] Specifically, the rheological properties refer to the deformation and flow properties of a material under the action of an external force. Different materials have different viscosities, and the quantitative relationship between the shear stress and the shear rate applied to the material is also different.

[0044] The adhesive film body has viscosity and is used to bond other film layers. The other film layers are, for example, engineering plastic film layers, thermoplastic elastomer film layers, fiber layers, etc. The adhesive film body can be, but is not limited to, a polyolefin adhesive film, an acrylate adhesive film, a polyvinyl alcohol adhesive film, a polyvinyl acetate adhesive film, a polyamide adhesive film, a polyurethane adhesive film, a silicone adhesive film, etc.

[0045] In preparation, the adhesive film body is formed by coating and then solvent evaporation. The adhesive film body has a small thickness and low strength. The thickness of the adhesive film body is usually several microns to tens of microns. The adhesive film body is usually made into an adhesive film assembly for storage, for example, the adhesive film body is sandwiched between a bottom release film and a top release film to form an adhesive film assembly. The bottom release film and the top release film are usually plastic films.

[0046] A release film is a release film material for preventing the adhesive film from sticking and protecting the adhesive film from contamination. The release film is made of a film coated with a release material. The release film includes a base film release film and a cover film release film. The base film release film is attached to one surface of the adhesive film body. The base film release film provides sufficient structural strength to the adhesive film assembly. The cover film release film is attached to the other surface of the adhesive film body. The cover film release film has low peel strength with the adhesive film and is easy to remove. In use of the adhesive film body, the cover film release film is usually removed first to expose one surface of the adhesive film body. The surface is used for bonding other components.

[0047] Generally, the peel strength of the base film release film is greater than that of the cover film release film, so the cover film release film is usually removed first, and then the base film release film is removed.

[0048] The inventors of the present disclosure found that, due to the small thickness and small strength of the adhesive film body, it is difficult to measure a single-layer adhesive film body, the measurement data has large error and low reference value, so it is necessary to stack multiple adhesive film bodies together to form a multi-layer adhesive film body with a set thickness for testing. This way not only meets the requirements of the testing equipment for the thickness of the to-be-tested piece, but also makes the measurement data error small and the reference value large. The testing method makes the multi-layer adhesive film body into a set thickness, measures the rheological properties of the multi-layer adhesive film body with the set thickness, and thus reflects the rheological properties of the single-layer adhesive film body.

[0049] In the S1 step, the number of adhesive film assemblies required is calculated according to the thickness of each adhesive film body and the thickness of the to-be-tested piece required by the testing equipment. Further, the sizes of the multiple adhesive film assemblies are consistent to ensure that the thicknesses of the to-be-tested piece stacked together at different positions are consistent.

[0050] In the S2 step, first, take one adhesive film assembly and remove the cover film release film of the adhesive film assembly to expose one surface of the adhesive film body. The adhesive film body has adhesion. Then, attach the base film release film to the workbench. For example, the surface of the base film release film opposite to the adhesive film body is bonded to the workbench by an adhesive to make the adhesive film body opposite to the workbench.

[0051] Of course, the base film release film can also be fixed to the workbench in other ways.

[0052] In the S3 step, multiple adhesive film bodies are stacked and bonded together to achieve a set thickness. When bonding, the adhesive film bodies are bonded layer by layer. The last bonded adhesive film assembly retains the base film release film. Finally, a to-be-tested piece with multiple adhesive film bodies sandwiched between two base film release films is formed. The base film release film can effectively protect the multiple adhesive film bodies.

[0053] The inventor of the present application found that during the laminating and bonding of the adhesive film body, the force applied by different persons is inconsistent, or the force applied by the same person to different parts of the adhesive film body is inconsistent. The above-mentioned situations lead to inconsistent residual stress of the test piece made by different persons from the same adhesive film. Inconsistent stress leads to large error and poor consistency of the test results when performing rheological property test. In order to obtain accurate and consistent rheological property test results, it is necessary to eliminate the residual stress of the test piece.

[0054] In step S4, the test piece is kept in a high temperature environment for a set time. In the high temperature environment, the microstructure of each adhesive film body is rearranged, so that the microstructure of different parts of the multilayer adhesive film body becomes uniform, thereby achieving the purpose of stress elimination.

[0055] In step S5, the rheological property test includes shear mode test and tensile mode test.

[0056] The shear mode test is tested by, for example, a flat plate rotor of a rotary rheometer. The flat plate rotor includes an upper rotor and a lower rotor. The upper rotor is arranged opposite to the lower rotor. The test piece is cut into a disc with the same size as the flat plate rotor. The thickness of the test piece is t, and when performing the shear mode test, the two bottom film release films of the disc-shaped test piece need to be removed. The thickness of the bottom film release film is t1. The thickness of the final multilayer adhesive film body is t-2t1.

[0057] During the preparation of the shear mode test, first, the bottom film release film on one side of the disc-shaped test piece is removed to expose the adhesive film body. Then, the adhesive film body is bonded to the lower rotor and coincides with the flat plate rotor. The bottom film release film on the other side of the multilayer adhesive film body faces away from the lower rotor. Next, the bottom film release film on the other side is removed. The upper rotor is lowered so that the distance between the upper rotor and the lower rotor is equal to the thickness of the multilayer adhesive film body. The upper rotor and the lower rotor are aligned. The thickness of the multilayer adhesive film body is the height of the gap between the upper and lower rotors. After the above preparation is completed, the shear mode test can be performed.

[0058] In the shear mode test, the test curve shows a large linear viscoelastic region due to the soft and elastic material of the adhesive film body. Therefore, the strain of the rotational rheometer is usually set to 0.2% to 1%. In the time-temperature superposition fitting test of the multilayer adhesive film body, the temperature points of the rotational rheometer are set at intervals of 5°C to 10°C. In the isothermal frequency sweep, the frequency range of the rotational rheometer is 0.16 Hz to 16 Hz (about (1-100) rad / s, wherein: 1 rad / s ≈ 0.16 Hz). The upper and lower limits of the temperature points are selected according to the size of the frequency range to be fitted. The rheological parameters that can be characterized by the shear mode test include shear storage modulus, shear loss modulus, shear loss factor, complex viscosity, shear creep, shear stress relaxation, and shear TTS time-temperature superposition fitting.

[0059] The tensile mode test is performed by using the tensile clamp of the dynamic mechanical analyzer, for example. For example, the sample to be tested is cut into a strip-shaped sample with a width of 3 mm to 6 mm and a length of 50 mm. The thickness of the sample to be tested is t, and the bottom film release film on both sides of the strip-shaped sample is removed during the tensile mode test. The thickness of the bottom film release film is t1. The thickness of the final multilayer adhesive film body is t-2t1.

[0060] During the preparation of the tensile mode test, first, the two layers of bottom film release film are removed, and then the multilayer adhesive film body is clamped into the tensile clamp. During the clamping process, the multilayer adhesive film body should be avoided from being excessively pulled, and the original size of the multilayer adhesive film body should be maintained as much as possible.

[0061] In the tensile mode test, the test curve shows a large linear viscoelastic region due to the soft and elastic material of the adhesive film body. Therefore, the strain of the dynamic mechanical analyzer is usually set to 0.2% to 1%. In the time-temperature superposition fitting test of the multilayer adhesive film body, the temperature points of the dynamic mechanical analyzer are set at intervals of 5°C to 10°C. In the isothermal frequency sweep, the frequency range of the dynamic mechanical analyzer is 0.1 Hz to 1 Hz. The rheological parameters that can be characterized by the tensile mode test include tensile storage modulus, tensile loss modulus, tensile loss factor, tensile creep, tensile stress relaxation, and tensile TTS time-temperature superposition fitting.

[0062] In the embodiments of the present disclosure, the multilayer adhesive film body is laminated and bonded together to form a sample to be tested with a set thickness to meet the thickness requirement of the test equipment for the sample to be tested. The performance of the adhesive film body is characterized by measuring the rheological properties of the sample to be tested with the set thickness. This method can effectively test and evaluate the rheological properties of the adhesive film body.

[0063] In addition, the multi-layer adhesive film body is prone to residual stress when being laminated and bonded. By keeping the multi-layer adhesive film body with the bottom film release film attached to both sides at a set temperature for a set time, the stress of the test piece can be effectively eliminated. This makes the rheological property test of the multi-layer adhesive film body more accurate and the consistency of the test results better.

[0064] In one example, in the S1 step, the edges of the adhesive film assembly with the film release film removed are fixed to the workbench by adhesive tape.

[0065] For example, the adhesive film assembly is rectangular. After the film release film is removed, one surface of the adhesive film body is exposed. This surface is used for bonding with the adhesive film body of another adhesive film assembly. When being fixed, the adhesive tape is bonded on the four edges of the adhesive film body. Both the adhesive film body and the adhesive tape have adhesion. This way makes the fixation of the adhesive film assembly on the workbench more secure.

[0066] In one example, in the S2 step, first, the film release film of each adhesive film is removed;

[0067] Then, the adhesive film body is bonded with the adhesive film body on the workbench;

[0068] Finally, the bottom film release film is removed.

[0069] When being laminated and bonded, first, the film release film of another adhesive film assembly is removed to expose one surface of the adhesive film body. This surface is used for bonding with the adhesive film body on the workbench.

[0070] Then, the adhesive film body of the other adhesive film assembly is bonded on the adhesive film body on the workbench.

[0071] Next, the bottom film release film of the other adhesive film assembly is removed to expose the other surface of the adhesive film body.

[0072] Next, the bonding steps described above are repeated to form a multi-layer adhesive film body. The bottom film release film of the last bonded adhesive film assembly is retained.

[0073] Finally, the adhesive tape is peeled off from the workbench and removed from the multi-layer adhesive film body to form a structure with the multi-layer adhesive film body sandwiched between the two bottom film release films.

[0074] In this example, the bottom film release film can effectively protect the multi-layer adhesive film body.

[0075] In one example, when bonding two adhesive film bodies, the bonding starts from the same side corresponding to the positions of the two adhesive film bodies and the doctor blade is used to scrape the bottom film release film from one side to the other side.

[0076] For example, the film body is rectangular. A spatula is used to scrape the release film from one edge of the two film bodies to the opposite edge, gradually bonding the two film bodies. The spatula can effectively eliminate air bubbles between the two film bodies, which will affect the accuracy of the test results. In this example, the release film has a higher hardness than the cover film, and can withstand the pressure and friction of the spatula.

[0077] In one example, before step S1, the plurality of film assemblies are cut into rectangular test pieces, with a width of 5-8 cm and a length of 10 cm.

[0078] The rectangular film assembly has a regular structure, which can more accurately align the multiple film bodies during lamination and bonding. The final test piece has better consistency in thickness.

[0079] The film assembly with the above size range has fewer air bubbles and less stress during lamination and bonding, and the lamination and bonding operation is easy to operate, meeting the requirements of rheological property testing.

[0080] In one example, the set thickness is 0.5-1 mm. This thickness range meets the sample thickness requirements of the rheological property testing equipment.

[0081] It should be noted that for different rheological property tests of different film bodies, the thickness of the laminated and bonded multiple film assembly should be kept consistent as much as possible. This method can effectively avoid the influence of thickness variation on the test results.

[0082] Of course, the set thickness is not limited to the above examples, and those skilled in the art can set it according to actual needs.

[0083] In one example, in step S5, the test piece is cut to a set size and shape, and the two release films are removed.

[0084] In different test modes, the size and shape of the test piece are different. In this example, the test piece is cut according to actual needs to meet the test requirements.

[0085] In one example, in step S4, the set temperature is 30-50°C, and the set time is 2-4 hours.

[0086] If the set temperature is too high, the damage to the film body will be greater, and irreversible deformation of the film body will be easily caused. If the set temperature is too low, the required holding time will be longer, affecting the timeliness of stress relief. The above conditions meet the stress relief needs of silicone film, acrylic film and other materials, and the stress relief speed is fast, and the irreversible deformation of the test piece is small.

[0087] In one example, in the S4 step, the test piece is placed into a thermostat. The thermostat has a constant temperature, and can form a good stress relief environment, so that the stress relief effect of the test piece is better.

[0088] <EMBODIMENT>

[0089] S11, a plurality of said adhesive film assemblies are provided. The adhesive film body is a polyacrylate adhesive film. The number is 100 pcs, and there are two kinds, respectively used for shear mode and tensile mode test. The length of the adhesive film assembly is 10 cm, and the width is 6 cm.

[0090] S12, take one adhesive film assembly. Remove the cover film release film of the adhesive film assembly, and bond the four edges of the adhesive film assembly to the workbench by adhesive tape. Four adhesive tapes are bonded to the edges of the four edges of the adhesive film assembly respectively, and contact with the adhesive film body. The bottom film release film of the adhesive film assembly contacts the workbench.

[0091] S13, take another adhesive film assembly. Remove the cover film release film of the adhesive film assembly. Bond the adhesive film body of the adhesive film assembly to the surface of the adhesive film body on the workbench. Then, remove the bottom film release film.

[0092] Repeat the above operation to bond a plurality of adhesive film bodies in turn until a multi-layer bonding structure with a set thickness is formed. Among them, the last adhesive film assembly retains the bottom film release film to form the test piece.

[0093] S14, take the test piece from the workbench, and place the test piece into a thermostat for constant temperature preservation to eliminate the stress of the test piece. The temperature of the thermostat is 35℃. The holding time is 3 hours.

[0094] S15, test the rheological properties of the test piece after stress relief. Among them, the thickness t of the test piece 1 is 1.15 mm. The thickness t1 of the bottom film release film is 0.047 mm, and the test piece is used for shear mode test.

[0095] The thickness t of the test piece 2 is 1.2 mm, and the thickness t1 of the bottom film release film is 0.035 mm. The test piece is used for tensile mode test.

[0096] (1) Shear mode test:

[0097] Cut the test piece 1 into a circular piece with a diameter of 8 mm. The flat plate rotor of the rotary rheometer is used for testing.

[0098] A, test item: storage modulus, loss modulus, loss factor.

[0099] Test conditions:

[0100] Temperature: -50℃ to 250℃

[0101] Oscillation frequency: 1Hz

[0102] Heating rate: 3℃ / min

[0103] Oscillation strain: 0.2%

[0104] Figure 2 The curves showing the changes in storage modulus, loss modulus, and loss factor with temperature for the shear mode test of the multilayer film body according to embodiments of this disclosure.

[0105] Where a represents the curve of energy storage modulus versus temperature, b represents the curve of loss modulus versus temperature, and c represents the curve of loss factor versus temperature.

[0106] By reading the values ​​of the horizontal and vertical axes, the energy storage modulus, loss modulus, and loss factor of the film body at a set temperature can be obtained.

[0107] from Figure 2 As can be seen from the curves, the glass transition temperature of the film is relatively low at -43.5℃. Subsequently, as the temperature rises, the storage modulus of the film decreases, with the decrease accelerating at 150℃. Later, with continued temperature increases, the film ages, and the storage modulus increases somewhat.

[0108] B. Test Item: TTS Time-Temperature Conversion

[0109] Test conditions:

[0110] Temperature gradient: -20℃, -15℃, -10℃, -5℃, 0℃, 5℃, 10℃, 15℃, 20℃, 25℃

[0111] Temperature gradient isotherm time: 600s

[0112] Scan frequency: 1 to 100 rad / s

[0113] Oscillation strain: 0.2%

[0114] Reference temperature: 25℃

[0115] Repeat the test: 3 times

[0116] Figure 3 The TTS time-temperature conversion curve is shown in the shear mode of the multilayer film body according to an embodiment of this disclosure.

[0117] Wherein, A is the change curve of the storage modulus under different temperature gradients with the angular frequency (1-100 rad / s). The multiple curves from far to close to the origin of the storage modulus coordinate are the change curves of-20℃, -15℃, -10℃, -5℃, 0℃, 5℃, 10℃, 15℃, 20℃, 25℃, respectively.

[0118] B is the change curve of the loss modulus under different temperature gradients with the angular frequency (1-100 rad / s). The multiple curves from far to close to the origin of the storage modulus coordinate are the change curves of-20℃, -15℃, -10℃, -5℃, 0℃, 5℃, 10℃, 15℃, 20℃, 25℃, respectively.

[0119] a is the change curve of the storage modulus after TTS temperature conversion with the scanning frequency.

[0120] b is the change curve of the loss modulus after TTS temperature conversion with the scanning frequency.

[0121] By reading the values of the abscissa and ordinate, the storage modulus and the loss modulus of the multilayer adhesive film body at the set scanning frequency can be obtained.

[0122] From Figure 3 It can be seen that through TTS temperature conversion, the frequency scanning data at low temperature can be equivalently converted into test data at high frequency at 25℃, so that the storage modulus, loss modulus and other parameters of the multilayer adhesive film body at acoustic vibration frequency (for example, 20Hz-20000Hz) are obtained, so as to objectively evaluate the mechanical properties of the multilayer adhesive film body at acoustic vibration frequency. The test is repeated for 3 times, and the repeatability effect is excellent.

[0123] (2) Tensile mode test:

[0124] The test piece 2 is cut into a rectangular piece with a length of 50mm and a width of 5mm. The tensile clamp of the dynamic thermal mechanical analyzer is used for testing.

[0125] A, test item: storage modulus, loss modulus, loss factor.

[0126] Test conditions: temperature: -50℃~200℃

[0127] Oscillation frequency: 1Hz

[0128] Temperature rising rate: 3℃ / min

[0129] Oscillation strain: 0.2%

[0130] Figure 4 The change curve of the storage modulus and the loss modulus of the multilayer adhesive film body of the embodiment of the present disclosure with temperature in the tensile mode test.

[0131] Wherein, A is the curve of loss factor changing with temperature. B is the curve of loss modulus changing with temperature. C is the curve of storage modulus changing with temperature.

[0132] By reading the values of the abscissa and ordinate, the storage modulus, loss modulus and loss factor of the multilayer film body at the set temperature can be obtained.

[0133] From the curve in FIG. 1, it can be seen that the glass transition temperature of the film body is -31°C; then, with the increase of temperature, the storage modulus of the film body decreases, and at 110°C, the film body continues to soften, and the force value is too small, exceeding the measurement limit of the equipment. The film body is elongated, and the test is interrupted. Figure 4

[0134] B. Test item: stress relaxation curve

[0135] Test temperature: 45°C

[0136] Strain: 20%

[0137] Soaking time: 5 min

[0138] Relaxation time: 10 min

[0139] Recovery time: 10 min

[0140] Figure 5 The curve of the relaxation modulus and strain recovery rate of the multilayer film body according to the embodiment of the present disclosure changing with time.

[0141] Wherein, a is the curve of strain recovery rate changing with time. b is the curve of strain changing with time. c is the curve of relaxation modulus changing with time.

[0142] By reading the values of the abscissa and ordinate, the relaxation modulus, strain and strain recovery rate of the multilayer film body at the set time can be obtained.

[0143] From the curve in FIG. 2, it can be seen that after the instantaneous application of 20% strain, the relaxation modulus instantaneously rises to about 0.16 MPa, and then instantaneously relaxes most of the relaxation modulus, and after 10 min of relaxation, the relaxation modulus is about 0.03 MPa. After the set strain is removed, the sample shape changes slowly recover, and after 10 min, the strain recovers from 20% to about 5%. The test can be used to evaluate the stress relaxation and deformation recovery ability after force removal of the multilayer film body.

[0144] ​While certain specific embodiments of the application have been described in detail herein for the purposes of exemplification and to provide a thorough and enabling disclosure, it will be understood that the application is not limited to the particular embodiments described. Any modifications of the methods and materials described herein, which come within the scope and spirit of the application, are to be considered within the scope of the application. The scope of the application is to be determined by the claims appended hereto, which are to be construed in accordance with the principles of patent law.

Claims

1. A method for testing the rheological properties of a glue film, characterized by, The adhesive film assembly comprises a bottom film release film, a cover film release film, and an adhesive film body attached between the bottom film release film and the cover film release film, the peel strength of the bottom film release film is greater than that of the cover film release film; the test method comprises: S1, providing a plurality of adhesive film assemblies, cutting the plurality of adhesive film assemblies into rectangular test pieces, the width of the rectangular test piece is 5-8 cm, and the length is 10 cm; S2, remove the cover film release film of one of the adhesive film assemblies, and fix the adhesive film assembly with the cover film release film removed to the workbench, the bottom film release film is in contact with the workbench; S3, sequentially remove the cover film release film and the bottom film release film of the remaining plurality of adhesive film assemblies, and stack and bond the plurality of adhesive film bodies together to achieve a set thickness, the set thickness is 0.5-1 mm, wherein the last adhesive film assembly retains the bottom film release film, so that the plurality of adhesive film bodies are located between two bottom film release films, and two bottom film release films and the plurality of adhesive film bodies located between the two bottom film release films are the test piece; S4, remove the test piece from the workbench, and heat the test piece at a set temperature for a set time to eliminate the stress of the test piece; the set temperature is 30-50℃, and the set time is 2-4 hours; S5, test the rheological properties of the stress-relieved test piece, and the rheological property test comprises shear mode test and tensile mode test.

2. The performance testing method of claim 1, wherein, In step S1, the edges of the adhesive film assembly with the cover film release film removed are fixed to the workbench by adhesive tape.

3. The method of testing the rheological properties according to claim 1, characterized in that, In step S2, first, remove the cover film release film of each adhesive film; Then, bond the adhesive film body with the adhesive film body on the workbench; Finally, remove the bottom film release film.

4. The method of testing the rheological properties according to claim 3, characterized in that, When bonding two adhesive film bodies, start from the same side of the two adhesive film bodies and gradually bond from one side to the other side, and use a spatula to scrape the bottom film release film from one side to the other side.

5. The method of testing the rheological properties according to claim 1, characterized in that In step S5, the test piece is cut into a set size and shape, and the two bottom film release films are removed.

6. The method of testing the rheological properties according to any one of claims 1-5, characterized in that In step S4, the test piece is placed in an incubator.

Images