Composite film and packaging structure and method thereof

Abstract

The present application provides a composite film and its packaging structure and method. The composite film includes a first thermoplastic elastomer film layer and a second thermoplastic elastomer film layer, wherein the first thermoplastic elastomer film layer includes a first styrenic block copolymer. The second thermoplastic elastomer film layer is disposed on the first thermoplastic elastomer film layer, wherein the second thermoplastic elastomer film layer includes a second styrenic block copolymer, diffusion particles dispersed in the second thermoplastic elastomer film layer, and a surface microstructure provided on the surface of the second thermoplastic elastomer film layer.

Description

Technical Field

[0001] This invention relates to a composite film and its encapsulation structure and encapsulation method. Background Technology

[0002] Small and medium-sized backlight modules are gradually being replaced by sub-millimeter (Mini) LED direct-lit backlight modules. Mini LED arrays distributed across LED units not only feature smaller spacing and a higher number of LED chips, but also reduce the mixing distance for thinner displays and enable local dimming for higher dynamic range. Current technology uses encapsulating materials, fully coated onto the LED units to protect the thousands of LEDs on their surface. Commonly used encapsulating materials include silicone, epoxy resin, and optical clear adhesive (OCA).

[0003] When several LEDs in a certain area fail and need to be replaced, or when air bubbles are generated during the encapsulation process, the traditional approach is to replace the entire Mini LED backlight module board, which is not only environmentally unfriendly but also costly. However, because the encapsulating adhesive is a thermosetting material, when removing the damaged LEDs, other LEDs in unspecified locations, regardless of their condition, may be pulled out by the adhesive, increasing the cost of repair and rework.

[0004] In summary, there is an urgent need to develop new packaging materials with easy disassembly characteristics. For example, thermoplastic packaging materials that can be plasticized and deformed at high temperatures can be easily debonded and removed from the light board by heating, without pulling the light-emitting diodes off the LED unit. Summary of the Invention

[0005] The present invention relates to a composite film that can be peeled off from the surface of a substrate to which the composite film is attached at a temperature below 80°C without leaving any adhesive residue.

[0006] According to an embodiment of the present invention, a composite film includes a first thermoplastic elastomer film layer, wherein the first thermoplastic elastomer film layer includes a first styrene-based block copolymer; and a second thermoplastic elastomer film layer disposed on the first thermoplastic elastomer film layer, wherein the second thermoplastic elastomer film layer includes a second styrene-based block copolymer, diffused particles dispersed in the second thermoplastic elastomer film layer, and surface microstructures disposed on the surface of the second thermoplastic elastomer film layer.

[0007] According to another embodiment of the present invention, a light-emitting diode backlight module includes a light-emitting diode unit having at least one surface; and the aforementioned composite film disposed on and encapsulated on the surface of the light-emitting diode unit.

[0008] According to another embodiment of the present invention, a method for packaging a light-emitting diode unit includes encapsulating the composite film onto the substrate surface of the light-emitting diode unit by hot pressing, wherein a first thermoplastic elastomer film layer in the composite film is in direct contact with the substrate surface. Attached Figure Description

[0009] Figure 1 This is a partial cross-sectional schematic diagram of a composite membrane according to an embodiment of the present invention.

[0010] Figure 2 This is a partial cross-sectional schematic diagram of a light-emitting diode backlight module according to another embodiment of the present invention.

[0011] Explanation of reference numerals in the attached figures

[0012] 100, 208: Composite membrane

[0013] 110, 210: First thermoplastic elastomer film layer

[0014] 120, 220: Second thermoplastic elastomer film layer

[0015] 130, 230: Diffused particles

[0016] 140, 240: Surface microstructure

[0017] 200: LED backlight module

[0018] 201: Substrate

[0019] 202: Light Emitting Diode Unit

[0020] 204: Surface

[0021] 206: Light Emitting Diode Detailed Implementation

[0022] Figure 1 This is a schematic cross-sectional view of a composite membrane according to one embodiment of the present invention. Please refer to... Figure 1 In an embodiment, the composite film 100 disclosed herein includes a first thermoplastic elastomer film layer 110, wherein the first thermoplastic elastomer film layer includes a first styrene-based block copolymer, and a second thermoplastic elastomer film layer 120 disposed on the first thermoplastic elastomer film layer 110, wherein the second thermoplastic elastomer film layer 120 includes a second styrene-based block copolymer, diffused particles 130 dispersed in the second thermoplastic elastomer film layer, and surface microstructures 140 disposed on the surface of the second thermoplastic elastomer film layer 120.

[0023] In some embodiments, the first styrene-based block copolymer in the first thermoplastic elastomer film layer 110 of the composite film 100 and the second styrene-based block copolymer in the second thermoplastic elastomer film layer 120 each include a first block derived from styrene and a second block derived from a styrene-ethylene-butene-styrene copolymer, wherein the weight ratio of styrene to styrene-ethylene-butene-styrene copolymer ranges from 0.2 / 1 to 0.35 / 1. When the weight ratio of styrene to styrene-ethylene-butene-styrene copolymer is too small, the adhesion between the composite film and the LED unit is low; when the weight ratio of styrene to styrene-ethylene-butene-styrene copolymer is too large, the composite film adhered to the LED module cannot pass the 85°C / 85% RH cycle test.

[0024] In some embodiments, the first thermoplastic elastomer film layer 110 of the composite film 100 further includes an adhesive.

[0025] In some embodiments, the weight ratio of the adhesive to the first styrene-based block copolymer in the first thermoplastic elastomer film layer 110 of the composite film 100 ranges from 0.05 / 1 to 0.2 / 1. When the weight ratio of the adhesive to the first styrene-based block copolymer is too small, the adhesion between the composite film and the light-emitting diode unit is low; when the weight ratio of the adhesive to the first styrene-based block copolymer is too large, the composite film adhered to the light-emitting diode unit cannot pass the 85°C / 85% RH cycle test, and air bubbles will be generated between the composite film and the light-emitting diode unit.

[0026] In some embodiments, the adhesive comprises a C5 aliphatic resin, dicyclopentadiene, or a C9 aromatic resin.

[0027] In some embodiments, the first styrene-based block copolymer is the same as the second styrene-based block copolymer.

[0028] In some embodiments, the first styrene-based block copolymer is different from the second styrene-based block copolymer.

[0029] In some embodiments, the diffusion particles 130 of the second thermoplastic elastomer film layer 120 of the composite film 100 include silicon dioxide, polymethyl methacrylate, polystyrene, titanium dioxide, or a combination thereof, and the content of diffusion particles ranges from 1 to 5 parts by weight, based on 100 parts by weight of the second thermoplastic elastomer film layer 120. When the content of diffusion particles 130 is too small, the adhesion between the composite film and the light-emitting diode unit is high, but the uniformity of the light-emitting diode backlight module will decrease; when the content of diffusion particles 130 is too large, the adhesion between the composite film and the light-emitting diode unit is low, and when the composite film is adhered to the light-emitting diode unit, it cannot pass the 85°C / 85% RH cycle test, and air bubbles will be generated between the composite film and the light-emitting diode unit.

[0030] In some embodiments, the particle size of the diffuser particles 130 in the second thermoplastic elastomer film layer 120 of the composite film 100 ranges from 2 to 10 micrometers. When the particle size of the diffuser particles 130 is too small, the haze is high and the transmittance is low, which will reduce the light emission intensity; when the particle size of the diffuser particles 130 is too large, the transmittance is high and the haze is low, which will reduce the uniformity of the LED backlight module.

[0031] In some embodiments, the surface microstructure of the second thermoplastic elastomer film layer 120 of the composite film 100 includes a pyramidal structure, a sinusoidal waveform structure, or a hemispherical structure, and the aspect ratio of its surface microstructure 140 ranges from 0.04 to 0.2. When the aspect ratio of the surface microstructure 140 is too small, the light diffusion is weak, and the overall light emission uniformity is poor; when the aspect ratio of the surface microstructure 140 is too large, the light will be focused, thus reducing the uniformity of the LED backlight module.

[0032] In some embodiments, the composite film 100 is peeled off from the surface of a substrate to which it is attached at a temperature below 80°C without leaving any adhesive residue.

[0033] Figure 2 This is a cross-sectional schematic diagram of a light-emitting diode backlight module 200 according to another embodiment of the present invention. Please refer to... Figure 2 According to one embodiment of the present disclosure, a light-emitting diode backlight module 200 includes a light-emitting diode unit 202 having at least one surface 204, and a composite film 208 disposed and encapsulated on the surface 204 of the light-emitting diode unit 202.

[0034] In some embodiments, the light-emitting diode unit 202 of the light-emitting diode backlight module 200 includes a substrate 201; and a plurality of light-emitting diodes 206 disposed on the substrate 201, and a composite film 208 configured and encapsulates the plurality of light-emitting diodes 206.

[0035] In some embodiments, the composite membrane 208 includes a first thermoplastic elastomer membrane layer 210, wherein the first thermoplastic elastomer membrane layer includes a first styrene-based block copolymer, and a second thermoplastic elastomer membrane layer 220 disposed on the first thermoplastic elastomer membrane layer 210, wherein the second thermoplastic elastomer membrane layer 220 includes a second styrene-based block copolymer, diffused particles 230 dispersed in the second thermoplastic elastomer membrane layer, and surface microstructures 240 disposed on the surface of the second thermoplastic elastomer membrane layer 220.

[0036] In some embodiments, the adhesion between the composite film 208 in the LED backlight module 200 and the surface 204 of the LED unit 202 is in the range of 1200gf / 25mm to 2000gf / 25mm.

[0037] This disclosure discloses an embodiment of a packaging method for a light-emitting diode backlight module 200, which includes encapsulating the composite film 208 onto the surface 204 of the substrate 201 of the light-emitting diode unit 202 by hot pressing, wherein the first thermoplastic elastomer film layer 210 in the composite film 208 is in direct contact with the surface 204 of the substrate 201.

[0038] In some embodiments, the packaging method of the LED backlight module 200 is carried out by hot pressing, with the hot pressing temperature ranging from 150°C to 180°C.

[0039] Therefore, the composite film disclosed herein can be plasticized and deformed within a temperature range of 150°C to 180°C, allowing for easy removal from the LED unit without pulling off the LED. Experiments are listed below to verify the effectiveness of the invention, but the invention is not limited to the following.

[0040] Example

[0041] The materials used in the following experimental examples include: the weight ratios of styrene to styrene-ethylene-butene-styrene copolymers of the first and second styrene block copolymers are 20% (SEBS, Kraton MD1648), 34% (SEBS, Kraton MD6951), 18% (SEBS, Taipol 6014), and 40% (SEBS, Tuftec H1053), respectively; adhesive (Cleartack, W140); and diffusion particles (Soken, SRP-200).

[0042] In the following experimental examples, the haze detection instrument used was a haze meter (manufacturer: Nippon Denshoku NDH-2000), which tested transmittance (TT%) and haze (Hz%); the aging test instrument used was a constant temperature and humidity chamber (manufacturer: KSON THS-A4T), and its measurement standard was IEC 60068-2-87 (85℃ / 85%RH / 300 hours); the uniformity test used a luminance meter (manufacturer: Pioneer Technology PR-655), which tested the light emission uniformity value below the module at room temperature (%U = I_lamp_interval / I_lamp_top × 100%); the adhesion test used a tensile tester (manufacturer: Guanglai Instruments QC-513A2-204), and its test conditions were to stretch the adhesive and the LED unit at 180° at room temperature and test the adhesion between the 25mm wide adhesive and the LED unit, and its measurement standard was ASTM D3330.

[0043] Experimental Example 1

[0044] The first styrene-based block copolymer (styrene / SEBS content of 20% (SEBS, Kraton MD1648)) and the second styrene-based block copolymer (styrene and styrene-ethylene-butene-styrene copolymer weight ratio of 20% (SEBS, Kraton MD1648)) are respectively fed into a twin-screw extruder. After being melted at high temperature, they are fed into a co-extrusion die and extruded from the double-layer co-extrusion die through the internal flow channel design of the die to form a double-layer film.

[0045] Then, after cooling, winding, and unwinding, the aforementioned double-layer film forms an integrally molded composite film. The composite mold comprises a second thermoplastic elastomer film layer on the upper layer, which contains a second styrene-based block copolymer (the weight ratio of styrene to styrene-ethylene-butene-styrene copolymer is 20%); and a first styrene-based block copolymer on the lower layer (the weight ratio of styrene to styrene-ethylene-butene-styrene copolymer is 20%).

[0046] The composite film formed by the above-mentioned double-layer co-extrusion die has a transmittance (TT%) of 87.66% and a haze (Hz%) of 89.02%. The thickness of the first thermoplastic elastomer film layer of the composite film is 250 μm and the thickness of the second thermoplastic elastomer film layer is 100 μm.

[0047] Next, the composite film is used for encapsulating a light-emitting diode (LED) unit. The steps include covering the substrate surface of the LED unit with the composite film and then placing it in a hot press machine. The hot press machine has an upper template and a lower template; the upper template has a surface microstructure, and the lower template is a flat planar structure. During the hot press bonding process, the first thermoplastic elastomer film layer of the composite film faces the substrate of the LED unit, while the second thermoplastic elastomer film layer faces the template with the surface microstructure. At a hot press temperature ranging from 150°C to 180°C, the first thermoplastic elastomer film of the composite film is hot-pressed onto the substrate of the LED unit, and the second thermoplastic elastomer film of the composite film forms a surface microstructure corresponding to the upper template of the hot press machine. After cooling, an LED backlight module is formed, the LED backlight module having LED units (including a substrate and multiple LEDs), and a composite film that configures and encapsulates the multiple LEDs; wherein the surface microstructure of the second thermoplastic elastomer film layer is a sinusoidal waveform structure, and the aspect ratio of the surface microstructure is 0.16. The uniformity (U%) of the LED backlight module is 58.46%, the adhesion between the composite film and the substrate of the LED unit is 970gf / 25mm, and it has passed the aging test at 85℃ / 85%RH / 300 hours.

[0048] Experimental Example 2

[0049] A composite film was formed using the same materials and preparation method as in Example 1, except that the raw material used in the first and second styrene-based block copolymers was styrene / SEBS with a content of 34% (Kraton MD6951). The composite film formed by the above-mentioned double-layer co-extrusion die had a transmittance (TT%) of 88.37%, a haze (Hz%) of 90.16%, and the thickness of the first thermoplastic elastomer film layer of the composite film was 250 μm and the thickness of the second thermoplastic elastomer film layer was 100 μm. A light-emitting diode (LED) backlight module was formed after hot pressing in a heated press, wherein the surface microstructure of the second thermoplastic elastomer film layer was a sinusoidal waveform structure with an aspect ratio of 0.16. The uniformity (U%) of the LED backlight module was 69.3%, the adhesion between the composite film and the substrate of the LED unit was 1130 gf / 25 mm, and it passed an aging test at 85°C / 85% RH / 300 hours.

[0050] Comparative Example 1

[0051] A composite film was formed using the same materials and preparation method as in Example 1, except that the raw material used in the first and second styrene-based block copolymers was styrene / SEBS content 18% (Taipol 6014). The composite film formed by the above-mentioned double-layer co-extrusion die had a transmittance (TT%) of 88.32% and a haze (Hz%) of 89.76%. The thickness of the first thermoplastic elastomer film layer of the composite film was 250 μm and the thickness of the second thermoplastic elastomer film layer was 100 μm. The LED backlight module formed after hot pressing in a heated press had a sinusoidal waveform surface microstructure in the second thermoplastic elastomer film layer with a depth-to-width ratio of 0.16. The uniformity (U%) of the LED backlight module was 56.67%. The adhesion between the composite film and the substrate of the LED unit was relatively low at 760 gf / 25 mm, and it passed the aging test at 85°C / 85% RH / 300 hours.

[0052] Comparative Example 2

[0053] A composite film was formed using the same materials and preparation method as in Example 1, except that the raw material used in the first and second styrene-based block copolymers was 40% styrene / SEBS (Tuftec H1053). The composite film formed by the above-mentioned double-layer co-extrusion die had a transmittance (TT%) of 89.1% and a haze (Hz%) of 89.98%. The thickness of the first thermoplastic elastomer film layer of the composite film was 250 μm, and the thickness of the second thermoplastic elastomer film layer was 100 μm. The resulting LED backlight module, formed after heat pressing, had a sinusoidal waveform surface microstructure in the second thermoplastic elastomer film layer with a depth-to-width ratio of 0.16. The uniformity (U%) of the LED backlight module was 69.9%. The adhesion between the composite film and the substrate of the LED unit was 1208gf / 25mm, but it failed the aging test at 85℃ / 85%RH / 300 hours.

[0054] Based on the results of Experimental Examples 1-2 and Comparative Examples 1-2, composite films formed by co-extruding first and second styrene block copolymers with different styrene / SEBS weight ratios without the addition of adhesives and diffusing particles, and further encapsulated in LED units, yielded composite films with the following optimal characteristics: the weight ratio of styrene to styrene-ethylene-butene-styrene copolymer in the first and second styrene block copolymers ranged from 0.2 / 1 to 0.34 / 1. Within this range, when the LEDs in the aforementioned LED units are damaged and need replacement, the composite film can be removed from the substrate of the LED unit using a hot air gun at approximately 80°C. Since the composite film is a thermoplastic elastomer, it can be completely removed from the substrate of the LED unit during disassembly without leaving any residue or pulling it off the LED.

[0055] When the weight ratio of styrene to styrene-ethylene-butene-styrene copolymer is less than 0.2 / 1, the adhesion between the composite mold and the LED unit is low; when the weight ratio of styrene to styrene-ethylene-butene-styrene copolymer thermoplastic elastomer is greater than 0.35 / 1, the LED module cannot pass the 85℃ / 85% RH cycle test.

[0056] Experimental Example 3

[0057] A first styrene-based block copolymer (34% styrene / SEBS content (Kraton MD 6951)) is mixed with 10% binder (W140) using a mixing and granulating machine to form a first mixture. The first mixture is then fed into a twin-screw extruder at a temperature between 140 and 170°C and a screw speed between 250 and 300 rpm. The second styrene-based block copolymer (34% styrene / SEBS content (Kraton MD 6951)) is fed into a twin-screw extruder at a temperature between 140 and 170°C and a screw speed between 250 and 300 rpm. After being melted at high temperature, the mixture is fed into a co-extrusion die and extruded from the double-layer co-extrusion die through the internal flow channel design of the die to form a double-layer film.

[0058] Then, after cooling, winding, and unwinding, the aforementioned double-layer film forms an integrally molded composite film. The composite film consists of a second thermoplastic elastomer film in the upper layer, which comprises a second styrene-based block copolymer (the weight ratio of styrene to styrene-ethylene-butene-styrene copolymer is 34%), and a first thermoplastic elastomer film in the lower layer, which comprises a first styrene-based block copolymer (the weight ratio of styrene to styrene-ethylene-butene-styrene copolymer is 34%) and 10% adhesive.

[0059] The composite film formed by the above-mentioned double-layer co-extrusion die has a transmittance (TT%) of 88.32% and a haze (Hz%) of 90.31%. The thickness of the first thermoplastic elastomer film layer of the composite film is 250 μm and the thickness of the second thermoplastic elastomer film layer is 100 μm.

[0060] The LED backlight module was formed by heating and pressing in the same manner as in Experimental Example 1. The surface microstructure of the second thermoplastic elastomer film layer is a sinusoidal waveform structure with an aspect ratio of 0.16. The uniformity (U%) of the LED backlight module is 70.1%. The adhesion between the composite film and the substrate of the LED unit is 2049 gf / 25 mm, and it passed an aging test at 85°C / 85% RH / 300 hours.

[0061] Experiment Example 4

[0062] A composite film was formed using the same materials and preparation method as in Example 3, except that 15% adhesive (W140) was added to the first styrene-based block copolymer. The transmittance (TT%) of the composite film formed by the above-mentioned double-layer co-extrusion die was 87.86%, and the haze (Hz%) was 89.82%. The thickness of the first thermoplastic elastomer film layer of the composite film was 250 μm, and the thickness of the second thermoplastic elastomer film layer was 100 μm. The light-emitting diode backlight module formed after heat pressing had a sinusoidal waveform surface microstructure in the second thermoplastic elastomer film layer with a depth-to-width ratio of 0.16. The uniformity (U%) of the light-emitting diode backlight module was 70.3%. The adhesion between the composite film and the substrate of the light-emitting diode unit was 2231 gf / 25 mm, and it passed the aging test at 85°C / 85% RH / 300 hours.

[0063] Experimental Example 5

[0064] A composite film was formed using the same materials and preparation method as in Example 3, except that 20% adhesive (W140) was added to the first styrene-based block copolymer. The transmittance (TT%) of the composite film formed by the above-mentioned double-layer co-extrusion die was 88.21%, and the haze (Hz%) was 90.67%. The thickness of the first thermoplastic elastomer film layer of the composite film was 250 μm, and the thickness of the second thermoplastic elastomer film layer was 100 μm. The light-emitting diode backlight module formed after heat pressing had a sinusoidal waveform surface microstructure in the second thermoplastic elastomer film layer, and the aspect ratio of the surface microstructure was 0.16. The uniformity (U%) of the light-emitting diode backlight module was 69.6%. The adhesion between the composite film and the substrate of the light-emitting diode unit was 2357 gf / 25 mm, and it passed the aging test at 85°C / 85%RH / 300 hours.

[0065] Comparative Example 3

[0066] A composite film was formed using the same materials and preparation method as in Example 3, except that 25% adhesive (W140) was added to the first styrene-based block copolymer. The transmittance (TT%) of the composite film formed by the above-mentioned double-layer co-extrusion die was 88.19%, and the haze (Hz%) was 89.56%. The thickness of the first thermoplastic elastomer film layer of the composite film was 250 μm, and the thickness of the second thermoplastic elastomer film layer was 100 μm. The light-emitting diode backlight module formed after heat pressing had a sinusoidal waveform surface microstructure in the second thermoplastic elastomer film layer with a depth-to-width ratio of 0.16. The uniformity (U%) of the light-emitting diode backlight module was 70.5%. The adhesion between the composite film and the substrate of the light-emitting diode unit was 2526 gf / 25 mm, but it failed the aging test at 85°C / 85% RH / 300 hours.

[0067] Based on the results of Experimental Examples 3-5 and Comparative Example 3, the weight ratio of styrene to styrene-ethylene-butene-styrene copolymer thermoplastic elastomer in the first thermoplastic elastomer film layer and the second thermoplastic elastomer film layer was fixed at 0.34 / 1. Without adding diffusing particles to the second thermoplastic elastomer film layer, but with different weight ratios of adhesive added to the first thermoplastic elastomer film layer, the composite film formed by the double-layer co-extrusion die, and further encapsulated in a light-emitting diode (LED) unit, yielded a composite film with a preferred weight ratio of adhesive to the first styrene-based block copolymer in the first thermoplastic elastomer film layer ranging from 0.05 / 1 to 0.2 / 1. Furthermore, when the LED in the aforementioned LED unit is damaged and needs replacement, a hot air gun at approximately 80°C can be used to remove the composite film from the substrate of the LED unit. Since the composite film is a thermoplastic elastomer, it can be completely removed from the substrate of the LED unit during disassembly without leaving any residue or pulling it off the LED.

[0068] When the adhesive weight ratio is less than 0.05 / 1, the adhesion between the composite film and the LED unit is low; when the adhesive weight ratio is greater than 0.2 / 1, the composite film will fail the 85℃ / 85%RH cycle test when it is pasted onto the LED unit, and air bubbles will be generated between the composite film and the LED unit.

[0069] Experimental Example 6

[0070] A first styrene-based block copolymer (34% styrene / SEBS content (Kraton MD 6951)) is mixed with 10% binder (W140) using a compounding granulator to form a second mixture. Next, the second styrene-based block copolymer (34% styrene / SEBS content (Kraton MD 6951)) is mixed with 1% diffused particles using the same compounding granulator to form a third mixture. The second mixture and the third mixture are respectively fed into a twin-screw extruder at a temperature between 140 and 170°C and a screw speed between 250 and 300 rpm; after being melted at high temperature, they are fed into a co-extrusion die and extruded through the internal flow channel design of the die to form a double-layer film.

[0071] Then, after cooling, winding, and unwinding, the aforementioned double-layer film forms an integrally molded composite film. The composite film comprises a second thermoplastic elastomer film in the upper layer, which contains a second styrene-based block copolymer (styrene to styrene-ethylene-butene-styrene copolymer in a weight ratio of 34%) and diffused particles dispersed in the second thermoplastic elastomer film layer, wherein the particle size of the diffused particles is 2 micrometers; and a first thermoplastic elastomer film in the lower layer, which contains a first styrene-based block copolymer (styrene to styrene-ethylene-butene-styrene copolymer in a weight ratio of 34%) and 10% adhesive.

[0072] The composite film formed by the above-mentioned double-layer co-extrusion die has a transmittance (TT%) of 88.37% and a haze (Hz%) of 90.3%. The thickness of the first thermoplastic elastomer film layer of the composite film is 250 μm and the thickness of the second thermoplastic elastomer film layer is 100 μm.

[0073] The LED backlight module was formed by heating and pressing in the same manner as in Experimental Example 1. The surface microstructure of the second thermoplastic elastomer film layer is a sinusoidal waveform structure with an aspect ratio of 0.16. The uniformity (U%) of the LED backlight module is 76.24%. The adhesion between the composite film and the substrate of the LED unit is 1915 gf / 25 mm, and it passed an aging test at 85°C / 85% RH / 300 hours.

[0074] Experimental Example 7

[0075] A composite film was formed using the same materials and preparation method as in Example 6, except that 3% by weight of diffusing particles (SRP-200) with a particle size of 2 micrometers was added to the second styrene-based block copolymer. The composite film formed by the above-mentioned double-layer co-extrusion die had a transmittance (TT%) of 83.42% and a haze (Hz%) of 98.5%. The thickness of the first thermoplastic elastomer film layer of the composite film was 250 μm, and the thickness of the second thermoplastic elastomer film layer was 100 μm. The light-emitting diode backlight module formed after heat pressing had a sinusoidal waveform surface microstructure in the second thermoplastic elastomer film layer with an aspect ratio of 0.16. The uniformity (U%) of the light-emitting diode backlight module was 88.7%. The adhesion between the composite film and the substrate of the light-emitting diode unit was 1783 gf / 25 mm, and it passed the aging test at 85°C / 85%RH / 300 hours.

[0076] Experimental Example 8

[0077] A composite film was formed using the same materials and preparation method as in Example 6, except that 5% by weight of diffusing particles (SRP-200) with a particle size of 2 micrometers was added to the second styrene-based block copolymer. The composite film formed by the above-mentioned double-layer co-extrusion die had a transmittance (TT%) of 60.01% and a haze (Hz%) of 99.5%. The thickness of the first thermoplastic elastomer film layer of the composite film was 250 μm, and the thickness of the second thermoplastic elastomer film layer was 100 μm. The light-emitting diode backlight module formed after heat pressing had a sinusoidal waveform surface microstructure in the second thermoplastic elastomer film layer with an aspect ratio of 0.16. The uniformity (U%) of the light-emitting diode backlight module was 85.1%. The adhesion between the composite film and the substrate of the light-emitting diode unit was 1353 gf / 25 mm, and it passed the aging test at 85°C / 85%RH / 300 hours.

[0078] Comparative Example 4

[0079] A composite film was formed using the same materials and preparation method as in Example 6, except that 7% by weight of diffusing particles (SRP-200) with a particle size of 2 micrometers was added to the second styrene-based block copolymer. The composite film formed by the above-mentioned double-layer co-extrusion die had a transmittance (TT%) of 43.2% and a haze (Hz%) of 99.7%. The thickness of the first thermoplastic elastomer film layer of the composite film was 250 μm, and the thickness of the second thermoplastic elastomer film layer was 100 μm. The light-emitting diode backlight module formed after heat pressing had a sinusoidal waveform surface microstructure in the second thermoplastic elastomer film layer with an aspect ratio of 0.16. The uniformity (U%) of the light-emitting diode backlight module was 83.6%. The adhesion between the composite film and the substrate of the light-emitting diode unit was 1129 gf / 25 mm, but it failed the aging test at 85°C / 85% RH / 300 hours.

[0080] Based on the results of Experimental Examples 6-8 and Comparative Example 4, the weight ratio of styrene to styrene-ethylene-butene-styrene copolymer thermoplastic elastomer in the first thermoplastic elastomer film layer and the second thermoplastic elastomer film layer was fixed at 0.34 / 1, and the weight ratio of adhesive to the first styrene-based block copolymer in the first thermoplastic elastomer film layer was fixed at 0.1 / 1. However, when different weight ratios of diffusing particles were added to the second thermoplastic elastomer film layer, the composite film formed by the double-layer co-extrusion die, and further encapsulated in the light-emitting diode unit, yielded a composite film with the following characteristics: 1 to 5 parts by weight of diffusing particles per 100 parts by weight of the second thermoplastic elastomer film layer. Within this range, when the light-emitting diode of the aforementioned light-emitting diode unit is damaged and needs to be replaced, the composite film can be removed from the substrate of the light-emitting diode unit using a hot air gun at a temperature of approximately 80°C. Since the composite film is a thermoplastic elastomer, it can be completely removed from the substrate of the light-emitting diode unit during disassembly without leaving any residue or pulling it off the light-emitting diode.

[0081] When the content of diffused particles is less than 1, the adhesion between the composite module and the LED unit is low, and the uniformity of the LED module decreases. When the content of diffused particles is greater than 5, the LED unit cannot pass the cyclic test at 85℃ / 85% RH.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A composite membrane, characterized in that, include: The first thermoplastic elastomer film layer includes a first styrene-based block copolymer; as well as A second thermoplastic elastomer film layer is disposed on the first thermoplastic elastomer film layer, wherein the second thermoplastic elastomer film layer comprises a second styrene-based block copolymer, a plurality of diffused particles dispersed in the second thermoplastic elastomer film layer, and surface microstructures disposed on the surface of the second thermoplastic elastomer film layer. The first styrene-based block copolymer and the second styrene-based block copolymer each include a first block derived from styrene and a second block derived from a styrene-ethylene-butene-styrene copolymer, wherein the weight ratio of styrene to the styrene-ethylene-butene-styrene copolymer ranges from 0.2 / 1 to 0.35 / 1.

2. The composite membrane according to claim 1, characterized in that, The first thermoplastic elastomer film layer also includes an adhesive.

3. The composite membrane according to claim 2, characterized in that, The weight ratio of the adhesive to the first styrene block copolymer in the first thermoplastic elastomer film layer ranges from 0.05 / 1 to 0.2 / 1.

4. The composite membrane according to claim 2, characterized in that, The adhesive comprises a C5 aliphatic resin, dicyclopentadiene, or a C9 aromatic resin.

5. The composite membrane according to claim 1, characterized in that, The first styrene-based block copolymer is the same as the second styrene-based block copolymer.

6. The composite membrane according to claim 1, characterized in that, The first styrene-based block copolymer is different from the second styrene-based block copolymer.

7. The composite membrane according to claim 1, characterized in that, The plurality of diffused particles in the second thermoplastic elastomer film layer include silica, polymethyl methacrylate, polystyrene, titanium dioxide, or a combination thereof, and the content of the plurality of diffused particles ranges from 1 to 5 parts by weight, based on 100 parts by weight of the second thermoplastic elastomer film layer.

8. The composite membrane according to claim 1, characterized in that, The particle size range of the plurality of diffused particles in the second thermoplastic elastomer film layer is 2 to 10 micrometers.

9. The composite membrane according to claim 1, characterized in that, The surface microstructure of the second thermoplastic elastomer film layer includes a pyramidal structure, a sinusoidal waveform structure, or a hemispherical structure, and the aspect ratio of the surface microstructure ranges from 0.04 to 0.

2.

10. The composite membrane according to claim 1, characterized in that, The composite film can be peeled off from the surface of a substrate to which it is attached at a temperature below 80°C without leaving any adhesive residue.

11. A light-emitting diode backlight module, characterized in that, include: A light-emitting diode unit has at least one surface; The composite film according to any one of claims 1 to 10 is configured and encapsulated on the surface of the light-emitting diode unit.

12. The light-emitting diode backlight module according to claim 11, characterized in that, The light-emitting diode unit includes: Substrate; and Multiple light-emitting diodes are disposed on the substrate, and the composite film encapsulates the multiple light-emitting diodes.

13. The light-emitting diode backlight module according to claim 11, characterized in that, The adhesion between the composite film and the surface of the light-emitting diode unit is in the range of 1200 gf / 25 mm to 2000 gf / 25 mm.

14. A method for packaging a light-emitting device, characterized in that, include: The composite film according to any one of claims 1 to 10 is encapsulated on the substrate surface of the light-emitting diode unit by hot pressing, and the first thermoplastic elastomer film layer in the composite film is in direct contact with the substrate surface.

15. The packaging method for the light-emitting device according to claim 14, characterized in that, The hot pressing temperature of the hot pressing method is in the range of 150°C to 180°C.

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