A zoned flexible stretch film and its preparation method and application

Abstract

The present invention discloses a regional flexible stretch film and a preparation method and application thereof, and relates to the field of mass transfer technology. The regional flexible stretch film includes a protective film layer, a temporary bonding adhesive layer and a stretchable substrate layer from top to bottom, a linear elastic deformable body is embedded in the stretchable substrate layer, and the linear elastic deformable body is composed of a plurality of polymer elastic columns, and the arrangement structure of the plurality of polymer elastic columns is any one of a horizontal linear arrangement, a vertical linear arrangement and a grid arrangement; the raw material of the polymer elastic column is a polymer elastic material; the material properties of the stretchable substrate layer and the linear elastic deformable body satisfy the following relationship: E2πd 2 =(4-400)E1LT. During the stretching and expansion process, the deformation degree of each position of the regional flexible stretch film of the present invention can be kept consistent, and the problem of uneven distribution of stress and deformation will not occur, which can make the chip spacing uniform and solve the defect of uneven distribution of stress and deformation of the existing flexible carrier film during the stretching and expansion process.

Description

Technical Field

[0001] The present invention relates to the field of mass transfer technology, and in particular to a regional flexible stretch film and a preparation method and application thereof. Background Art

[0002] Micro-LED technology, namely LED miniaturization and matrix technology, refers to the integration of a high-density, tiny-sized LED array on a chip. For example, each pixel in an LED display can be addressed and driven to light up individually. It can be seen as a miniature version of an outdoor LED display, reducing the pixel distance from millimeters to microns.

[0003] After the Micro-LED chips are manufactured, a large number (tens of thousands to tens of millions) of Micro-LED chips need to be transferred to a driver circuit board to form an LED array. Currently, the main mass transfers are divided into several categories: (1) Fine Pick / Place; (2) Selective Release: The LED is transferred directly from the original substrate without going through the picking process. The main technologies include patterned laser: using excimer laser to irradiate the sparsely dispersed mold-sized area on the gallium nitride slice on the growth interface, and then generating gallium metal and nitrogen through ultraviolet exposure, so as to achieve parallel transfer to the substrate and realize precise optical array; (3) Self-assembly, mainly using fluid force technology: using a brush bucket to roll on the substrate, so that the LED is placed in a liquid suspension, and through fluid force, the LED falls into the corresponding well on the substrate; (4) Roll Printing, transfer by printing, pick up the thin film transistor (TFT) element and place it on the required substrate, and then pick up the LED element and place it on the substrate with the TFT element, thereby completing the active matrix Micro-LED panel combining the two elements.

[0004] The above mass transfer method has high technical requirements, and the process and operation are relatively complicated, so it has not been widely used. For this reason, people have proposed a simpler new mass transfer method, that is, using a flexible carrier film to bond the chip for mass transfer. This transfer method first stretches and expands the flexible carrier film bonded with the chip to increase the chip spacing, and then transfers the chip to the substrate, thereby realizing the mass transfer and precise placement of Micro-LED. Chinese patent CN112071798A discloses a transfer film and its application in Micro-LED mass transfer. The transfer film includes a substrate and an acrylic adhesive layer and a debonding adhesive layer arranged on both sides of the substrate. The surfaces of the acrylic adhesive layer and the debonding adhesive layer are also covered with release film layers respectively. The material of the debonding adhesive layer is UV debonding adhesive. However, since the thickness and performance of the transfer film (flexible carrier film) are difficult to achieve absolute uniformity, the deformation degree of each position cannot be kept consistent during the stretching and expansion process, and the problem of uneven stress and deformation distribution will occur, making it difficult to ensure equal spacing for all chips. This has become one of the biggest problems in the practical application of the new mass transfer method. Summary of the invention

[0005] In response to the problems raised by the background technology, the purpose of the present invention is to propose a regional flexible stretch film. During the stretching and expansion process, the deformation degree of each position of the regional flexible stretch film can be kept consistent, and the problem of uneven stress and deformation distribution will not occur. The chip spacing can be made uniform, which solves the defect of uneven stress and deformation distribution of existing flexible carrier films during the stretching and expansion process.

[0006] Another object of the present invention is to provide a method for preparing a regional flexible stretch film, which has a simple preparation process and low operating difficulty.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] A regional flexible stretch film, comprising, from top to bottom, a protective film layer, a temporary bonding adhesive layer and a stretchable substrate layer, wherein a linear elastic deformable body is embedded in the stretchable substrate layer, wherein the linear elastic deformable body is composed of a plurality of polymer elastic columns, and the arrangement structure of the plurality of polymer elastic columns is any one of a transverse linear arrangement, a longitudinal linear arrangement and a grid arrangement;

[0009] The raw material of the polymer elastic column is a polymer elastic material;

[0010] The material properties of the stretchable substrate layer and the linear elastic deformable body satisfy the following relationship:

[0011] E2πd 2 =(4~400)E1LT;

[0012] In the above relationship, E2 is the elastic modulus of the linear elastic deformer, d is the diameter of the polymer elastic column, E1 is the elastic modulus of the stretchable substrate layer, L is the original width of two adjacent polymer elastic columns, T is the original thickness of the regional flexible stretch film, and the value of π is 3.1416.

[0013] Furthermore, the raw materials of the stretchable substrate layer are composed of thermoplastic polyurethane and polyolefin elastomer, and the mass ratio of the thermoplastic polyurethane, the polyolefin elastomer and the polymer elastic material in the total raw materials used for the stretchable substrate layer and the linear elastic deformer is (2-3): (0.5-1): (0.5-0.8).

[0014] Furthermore, the polymer elastic material is selected from any one or more combinations of styrene-butadiene rubber, butyl rubber, silicone rubber and polydimethylsiloxane.

[0015] Furthermore, in terms of mass percentage, the raw materials of the temporary bonding adhesive layer include 30-50 parts of resin, 50-70 parts of solvent, 9-11 parts of tackifier, 0.06-0.08 parts of leveling agent and 0.02-1 parts of antioxidant.

[0016] Furthermore, the thermal decomposition temperature of the resin in the temporary bonding adhesive layer is ≥320°C.

[0017] Furthermore, the resin in the temporary bonding adhesive layer is a network polymer formed by a polycondensation reaction of polyalkyl acrylate and / or diamine compound with aliphatic aldehyde, or is a synthetic resin.

[0018] Furthermore, the thickness of the protective film layer 1 is 100 μm to 150 μm;

[0019] The thickness of the temporary bonding adhesive layer 2 is 200 μm to 350 μm;

[0020] The thickness of the stretchable substrate layer 3 is 300 μm to 400 μm.

[0021] Furthermore, the regional flexible stretch film is used in array expansion.

[0022] Furthermore, the regional flexible stretch film is used in the mass transfer of Micro-LEDs.

[0023] A method for preparing a regional flexible stretch film, used for preparing the regional flexible stretch film, comprises the following steps:

[0024] (1) pouring a polymer elastic material into a mold, and after the polymer elastic material is cured, a linear elastic deformable body having a structure corresponding to the mold is obtained, and the mold has any one of a transverse linear arrangement structure, a longitudinal linear arrangement structure, and a grid arrangement structure;

[0025] (2) mixing thermoplastic polyurethane and polyolefin elastomer to prepare a substrate mixed emulsion; after the linear elastic deformable body is separated from the mold, the mixed emulsion is spin-coated on the surface of the linear elastic deformable body, and after curing, a stretchable substrate layer is formed;

[0026] (3) spin coating a temporary bonding adhesive solution on the surface of the stretchable substrate layer, and forming a temporary bonding adhesive layer after curing;

[0027] (4) Bonding the protective film to the temporary bonding adhesive layer to form a protective film layer on the surface of the temporary bonding adhesive layer, and applying pressure to the protective film layer to obtain a regional flexible stretch film.

[0028] The above technical solution has the following beneficial effects: the present technical solution provides a regional flexible stretch film, which has a three-layer structure, including a protective film layer, a temporary bonding adhesive layer, and a stretchable substrate layer from top to bottom. A linear elastic deformable body with a grid arrangement is embedded in the interior of the stretchable substrate layer, so the stretching deformation of the flexible film is more uniform. Since the raw material of the linear elastic deformable body is a polymer elastic material, the polymer elastic material undergoes uniform elastic deformation during the stretching process. The polymer elastic material follows Hooke's law within its elastic range (that is, when the stress is lower than the yield strength). After the solid material is subjected to force, the stress and strain (unit deformation) are linearly related. According to Hooke's law: σ=Eε (the stress σ in the solid is proportional to the strain ε, where E is a constant), when a certain tensile force is applied, the deformation is fixed. Therefore, the deformation of the regional flexible stretch film embedded in the linear elastic deformable body is more uniform, so that all chips are enlarged at equal intervals, the chips can be transferred more accurately, and the chip transfer efficiency is improved. It can be widely used in the mass transfer of Micro-LEDs, thereby solving the defect of uneven stress and deformation distribution of existing flexible carrier films during stretching and expansion. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic structural diagram of a regional flexible stretch film according to an embodiment of the present invention;

[0030] Figure 2 It is an unstretched grid-shaped, zoned flexible stretch film;

[0031] Figure 3 A schematic diagram of the structure of a polymer elastic column in one embodiment of the present invention;

[0032] Figure 4It is a regional flexible stretch film after transverse stretching;

[0033] Figure 5 It is a regional flexible stretch film after being stretched in the transverse and longitudinal directions;

[0034] Among them, the protective film layer 1, the temporary bonding adhesive layer 2, the stretchable substrate layer 3, the linear elastic deformation body 4, the Micro-LED chip 5, Figure 1 T is the original thickness of the flexible stretch film in each region. Figure 2 The L in is the original width of a single network. Figure 3 Where d is the diameter of the polymer elastic column. DETAILED DESCRIPTION

[0035] The technical solution of the present invention is further explained below in conjunction with the accompanying drawings and specific implementation methods.

[0036] A regional flexible stretch film, comprising, from top to bottom, a protective film layer 1, a temporary bonding adhesive layer 2 and a stretchable substrate layer 3, wherein a linear elastic deformable body 4 is embedded in the stretchable substrate layer 3, wherein the linear elastic deformable body 4 is composed of a plurality of polymer elastic columns, and the arrangement structure of the plurality of polymer elastic columns is any one of a transverse linear arrangement, a longitudinal linear arrangement and a grid arrangement;

[0037] The raw material of the polymer elastic column is a polymer elastic material;

[0038] The material properties of the stretchable substrate layer 3 and the linear elastic deformable body 4 satisfy the following relationship:

[0039] E2πd 2 =(4~400)E1LT;

[0040] In the above relationship, E2 is the elastic modulus of the linear elastic deformer 4, d is the diameter of the polymer elastic column, E1 is the elastic modulus of the stretchable substrate layer 3, L is the original width of two adjacent polymer elastic columns, T is the original thickness of the regional flexible stretch film, and the value of π is 3.1416.

[0041] Since the thickness and performance of existing flexible carrier films are difficult to achieve absolute uniformity, the degree of deformation at each position of the flexible carrier film is difficult to maintain consistency during the stretching and expansion process, which will lead to uneven distribution of stress and deformation, making it difficult to ensure equal spacing for all chips. This has become a difficult problem in practical applications of mass transfer.

[0042] In order to solve the above problems, the present technical solution provides a regional flexible stretch film, which has a three-layer structure, including a protective film layer 1, a temporary bonding adhesive layer 2, and a stretchable substrate layer 3 from top to bottom. A linear elastic deformable body 4 with a grid arrangement is embedded in the stretchable substrate layer 3, so that the stretching deformation of the flexible film is more uniform. Since the raw material of the linear elastic deformable body 4 is a polymer elastic material, the polymer elastic material undergoes uniform elastic deformation during the stretching process. The polymer elastic material follows Hooke's law within its elastic range (that is, when the stress is lower than the yield strength). After the solid material is subjected to force, the stress and strain (unit deformation) are linearly related. According to Hooke's law: σ=Eε (the stress σ in the solid is proportional to the strain ε, where E is a constant), when a certain tensile force is applied, its deformation is fixed. Therefore, the deformation of the regional flexible stretch film embedded in the linear elastic deformable body 4 is more uniform, so that all chips are enlarged at equal intervals, the chips can be transferred more accurately, and the chip transfer efficiency is improved. It can be widely used in the mass transfer of Micro-LEDs, thereby solving the defect of uneven stress and deformation distribution of existing flexible carrier films during stretching and expansion.

[0043] Specifically, the protective film layer 1 can play a protective role, prevent the temporary bonding layer from attracting dust particles, maintain the cleanliness of the regional flexible stretch film, thereby ensuring the mass transfer efficiency and facilitating the preservation of the regional flexible stretch film. The temporary bonding layer 2 can be used to bond the chip, and the stretchable substrate layer 3 can give the flexible film a certain elastic modulus for spacing adjustment. Since the linear elastic deformation body 4 is embedded in the stretchable substrate layer 3, and the linear elastic deformation body 4 has a horizontal linear arrangement structure, a longitudinal linear arrangement structure and a grid arrangement structure, the linear elastic deformation body 4 is arranged in a grid on the stretchable substrate layer 3 to divide the chip into regions, realize regional transfer correction, and adjust the chip to equal spacing, which greatly improves the accuracy and controllability of the chip spacing adjustment. At the same time, in the process of mass transfer of chips, the linear elastic deformable body 4 arranged in a grid within the regional flexible stretch film is conducive to aligning the chip with the target position of the carrier substrate, so as to more accurately adjust the displacement of the moving platform of the regional flexible stretch film. In the process of stretching and expanding the regional flexible stretch film using the technical solution, the degree of deformation at each position remains consistent, and the stress and deformation are evenly distributed, so that all chips are enlarged at equal intervals.

[0044] Further explanation, the material properties of the stretchable substrate layer 3 and the linear elastic deformable body 4 satisfy the following relationship: E2πd 2=(4~400)E1LT, which can ensure that the elastic modulus between the flexible stretch film and the linear elastic material can achieve the best stretching effect, prevent the elastic modulus of the linear elastic deformable body 4 arranged in a grid from being too large, and avoid the film being stretched while the elastic material is not stretched, or the elastic material being stretched while the film cannot be stretched during the stretching process.

[0045] Specifically, when the regional flexible stretch film is used for uniaxial stretching in the XY axis, the arrangement structure of the linear elastic deformable body 4 can be selected as a horizontal linear arrangement or a longitudinal linear arrangement; when the regional flexible stretch film is used for simultaneous or sequential stretching in the XY axis, the arrangement structure of the linear elastic deformable body 4 can be selected as a grid arrangement.

[0046] Specifically, the shape of the regional flexible stretch film in the present technical solution is any one of a rectangle, a square, a triangle and a polygon.

[0047] Preferably, the protective film layer 1 in the present technical solution is a polyethylene film.

[0048] like Figure 1-5 As shown, after the protective film layer 1 is torn off from the regional flexible stretch film, the tiny object Micro-LED chips are bonded in an array on the temporary bonding layer 2, such as Figure 2 As shown in FIG. 1 , the Micro-LED chip is divided into uniform square areas by the regional flexible stretch film. The regional flexible stretch film after lateral stretching is as shown in FIG. Figure 4 As shown in the figure, after lateral stretching, the spacing between the Micro-LED chips on the flexible stretch film in different regions becomes larger and remains consistent, and the longitudinal spacing between the chips remains unchanged; Figure 4 The regional flexible stretch film is stretched longitudinally, and the results are as follows Figure 5 As shown, the longitudinal spacing increases after stretching, and the longitudinal spacing remains consistent. After horizontal and longitudinal stretching, the spacing between Micro-LED chips increases and remains consistent.

[0049] Further explanation, the raw materials of the stretchable substrate layer 3 are composed of thermoplastic polyurethane and polyolefin elastomer, and in the total raw materials used for the stretchable substrate layer 3 and the linear elastic deformer 4, the mass ratio of the thermoplastic polyurethane, the polyolefin elastomer and the polymer elastic material is (2~3): (0.5~1): (0.5~0.8).

[0050] It is worth noting that, in the total amount of raw materials used for the stretchable substrate layer 3 and the linear elastic deformer 4, the mass ratio of thermoplastic polyurethane, polyolefin elastomer and polymer elastic material is (2-3): (0.5-1): (0.5-0.8). The use of the above mass ratio of the three can enable the stretchable substrate layer 3 to obtain better mechanical properties, tensile properties, elastic properties, and toughness, and at the same time have strong resistance to damage and wear, and the residual stress is small when the stretchable substrate layer 3 is deformed. The raw materials of the stretchable substrate layer 3 are composed of thermoplastic polyurethane and polyolefin elastomer. These two polymers have good elasticity, good physical properties, good mechanical strength, excellent high tension, high tensile force, strong toughness and aging resistance, and are environmentally friendly materials. The mass ratio of thermoplastic polyurethane and polyolefin elastomer is limited to (2-3): (0.5-1), which can maximize the advantages of the two materials.

[0051] To further illustrate, the polymer elastic material is selected from any one or more combinations of styrene-butadiene rubber, butyl rubber, silicone rubber and polydimethylsiloxane.

[0052] It is worth pointing out that high molecular elastic materials such as styrene-butadiene rubber, butyl rubber, silicone rubber and polydimethylsiloxane can enable the stretchable substrate layer 3 to obtain better mechanical properties, tensile properties, elastic properties and toughness, and at the same time have strong resistance to damage and wear. The residual stress of the regional flexible stretch film is small when it is deformed. At the same time, it can also obtain good mechanical strength, and has excellent high tension, high tensile force, strong toughness and aging resistance. In addition, styrene-butadiene rubber, butyl rubber, silicone rubber and polydimethylsiloxane are all mature environmentally friendly materials.

[0053] To further illustrate, in terms of mass percentage, the raw materials of the temporary bonding adhesive layer 2 include 30-50 parts of resin, 50-70 parts of solvent, 9-11 parts of tackifier, 0.06-0.08 parts of leveling agent and 0.02-1 parts of antioxidant.

[0054] Preferably, the solvent used in the temporary bonding adhesive layer 2 is any one or more combinations of ethylene glycol, propylene glycol, styrene, perchloroethylene, trichloroethylene, ethylene glycol ether and triethanolamine.

[0055] Preferably, the tackifier used in the temporary bonding adhesive layer 2 is any one or more combinations of aqueous tackifying emulsion, aqueous tackifying resin, aqueous tackifying powder, tackifying rosin resin and modified rosin resin, wherein the modified rosin resin is selected from any one or more combinations of hydrogenated rosin, polymerized rosin, maleic rosin, rosin glycerol ester and hydrogenated rosin glycerol ester.

[0056] Preferably, the leveling agent used in the temporary bonding adhesive layer 2 is a high-boiling point organic solvent or a mixture thereof, such as any one or more combinations of isophorone, diacetone alcohol, polydimethylsiloxane and polymethylphenylsiloxane.

[0057] Preferably, the antioxidant used in the temporary bonding adhesive layer 2 is selected from any one or more combinations of zinc dialkyl dithiophosphate, zinc dialkyl dithiocarbamate, N-phenyl-α-naphthylamine and alkyl phenothiazine.

[0058] As a further explanation, the thermal decomposition temperature of the resin in the temporary bonding adhesive layer 2 is ≥320°C.

[0059] Specifically, the temporary bonding adhesive layer 2 uses a resin with a thermal decomposition temperature ≥ 320°C, which can ensure that the regional flexible stretch film still maintains good viscosity in a more extreme working environment and ensures that the object (chip) can be firmly bonded. At the same time, by selecting a resin with a thermal decomposition temperature ≥ 320°C, the decomposition temperature of the temporary bonding adhesive layer is greater than 320°C, which can ensure that the regional flexible stretch film can be used in a reflow soldering process with a temperature as high as 230°C.

[0060] To further illustrate, the resin in the temporary bonding adhesive layer 2 is a network polymer formed by a polycondensation reaction of polyalkyl acrylate and / or diamine compound with aliphatic aldehyde, or is a synthetic resin.

[0061] Preferably, the synthetic resin in the present technical solution is any one of polyamide resin, paraformaldehyde and phenolic resin.

[0062] Further explanation, the thickness of the protective film layer 1 is 100 μm to 150 μm;

[0063] The thickness of the temporary bonding adhesive layer 2 is 200 μm to 350 μm;

[0064] The thickness of the stretchable substrate layer 3 is 300 μm to 400 μm.

[0065] Further explanation, the regional flexible stretch film is used in array expansion.

[0066] Further explanation: The regional flexible stretch film is used in the mass transfer of Micro-LED.

[0067] It is worth noting that when the regional flexible stretch film is used in array expansion and mass transfer of Micro-LED, the application method includes the following steps:

[0068] (1) tearing off the protective film layer 1 of the regional flexible stretch film;

[0069] (2) transferring the object to the temporary bonding adhesive layer 2 of the regional flexible stretch film;

[0070] (3) expanding the flexible stretch film in different regions, and using a machine vision system to detect the distance between objects in each block area;

[0071] (4) When the distance between the objects reaches 2 cm to 3 cm, the mobile platform is used to adjust the position of the regional flexible stretch film to align the objects to the target position of the supporting substrate;

[0072] (5) Laser irradiation is used from above the regional flexible stretch film to separate the object from the temporary bonding adhesive surface and transfer it to the target position of the supporting substrate.

[0073] Specifically, when the regional flexible stretch film is used in the mass transfer of Micro-LED, the above-mentioned object is the Micro-LED chip.

[0074] Specifically, in the above step (3), laser irradiation is used above the regional flexible stretch film. Because the laser generates heat in the focusing area after focusing, when the temperature reaches above 320°C, the resin of the temporary bonding layer 2 undergoes thermal decomposition and loses its viscosity, and the object is separated from the temporary bonding layer 2.

[0075] Preferably, step (3) further comprises pre-stretching the regional flexible stretch film before expansion, and grasping the deformation distribution of each region of the regional flexible stretch film through pre-stretching, and screening out the regional flexible stretch film with large deformation error, and recording the region where the regional flexible stretch film produces non-uniform deformation during the pre-stretching process, and monitoring the stretching degree of the region during the subsequent expansion process, and transferring the tiny objects in the region first or last.

[0076] Preferably, the chips with qualified spacing in a specific area are transferred first, and after the chip spacing in a part of the area is transferred, the sub-regional flexible stretch film is expanded to make the remaining chip spacing reach the appropriate spacing, and the transfer of all chips is completed in sequence. By preferentially transferring the qualified area and adjusting the area with inappropriate spacing at the same time, the detection and expansion can be carried out simultaneously, which improves the transfer efficiency, and there is no need to adjust all the spacings of the sub-regional flexible stretch film before transferring the chip.

[0077] A method for preparing a regional flexible stretch film, used for preparing the regional flexible stretch film, comprises the following steps:

[0078] (1) pouring a polymer elastic material into a mold, and after the polymer elastic material is cured, a linear elastic deformable body having a structure corresponding to the mold is obtained, and the mold has any one of a transverse linear arrangement structure, a longitudinal linear arrangement structure, and a grid arrangement structure;

[0079] (2) mixing thermoplastic polyurethane and polyolefin elastomer to prepare a substrate mixed emulsion; after the linear elastic deformable body is separated from the mold, the mixed emulsion is spin-coated on the surface of the linear elastic deformable body, and after curing, a stretchable substrate layer is formed;

[0080] (3) spin coating a temporary bonding adhesive solution on the surface of the stretchable substrate layer, and forming a temporary bonding adhesive layer after curing;

[0081] (4) Bonding the protective film to the temporary bonding adhesive layer to form a protective film layer on the surface of the temporary bonding adhesive layer, and applying pressure to the protective film layer to obtain a regional flexible stretch film.

[0082] It is worth noting that the technical solution embeds a grid-shaped polymer elastic material inside the stretchable substrate layer 3. If the stretchable substrate layer 3 is not embedded with the polymer elastic material, the regional flexible stretch membrane will have uneven deformation during the stretching process due to the uneven microscopic performance. However, after embedding the linear elastic deformable body 4, the linear elastic deformable body 4 and the regional flexible stretch membrane are an integrated structure. Since the polymer elastic material has a higher strength than the stretchable substrate layer 3 and the deformation is linear within the elastic range, the polymer elastic material can constrain the non-uniform deformation of the stretchable substrate layer 3, so that the stretchable substrate layer 3 can finally be stretched evenly, thereby making the stretching deformation of the regional flexible stretch membrane more uniform.

[0083] It is worth pointing out that if the stretchable substrate layer in the regional flexible stretch film of the present technical solution does not contain a polymer elastic material, the stretching deformation will not be uniform, making it difficult to accurately transfer the chip; if the raw material of the temporary bonding layer is UV viscosity-reducing glue, the chip cannot be bonded, because the focusing performance of UV light is not as good as that of laser, and precise quantitative bonding and release cannot be performed, which is not suitable for the mass transfer of microchips; if the thermoplastic polyurethane and polyolefin elastomer in the raw material of the stretchable substrate layer 3 are replaced by polymethyl methacrylate (PMMA), due to the low impact strength of PMMA, poor heat resistance, wear resistance and scratch resistance, it cannot withstand the temperature after laser focusing, and has poor comprehensive physical properties, which will result in the inability to obtain appropriate values ​​of the elastic modulus and Poisson's ratio.

[0084] The technical solution of the present invention is further described below in conjunction with embodiments.

[0085] Example 1

[0086] A zoned flexible stretch film comprises, from top to bottom, a protective film layer, a temporary bonding adhesive layer, and a stretchable substrate layer, wherein a linear elastic deformable body is embedded in the stretchable substrate layer, and the linear elastic deformable body is composed of a plurality of polymer elastic columns, wherein the arrangement structure of the plurality of polymer elastic columns is a grid-like arrangement structure, and the plurality of polymer elastic columns are integrally formed;

[0087] Among them, the protective film layer is a polyethylene film with a thickness of 150μm;

[0088] The raw materials of the temporary bonding adhesive layer are composed of resin (phenolic resin 40g), solvent (propylene glycol 50g), tackifier (rosin tackifier 10g), leveling agent (diacetone alcohol 0.08g), antioxidant (dialkyl dithiophosphate zinc 1g), and the thickness of the temporary bonding adhesive layer is 250μm;

[0089] The raw material of the stretchable substrate layer consists of 30g of thermoplastic polyurethane and 10g of polyolefin elastomer, the raw material of the linear elastic deformation body consists of 8g of polymer elastic material (styrene-butadiene rubber), and the thickness of the stretchable substrate layer is 400μm.

[0090] The method for preparing a regional flexible stretch film comprises the following steps:

[0091] (1) pouring a curable styrene-butadiene rubber emulsion into a mold having a grid-like arrangement structure, and after the styrene-butadiene rubber emulsion is cured, a linear elastic deformable body having a grid-like arrangement structure is obtained;

[0092] (2) According to the above formula, thermoplastic polyurethane emulsion and polyolefin elastomer emulsion are mixed to prepare substrate mixed emulsion (transparent), the casting mold on the surface of the linear elastic deformable body is removed, and the substrate mixed emulsion is spin-coated on the surface of the solidified linear elastic deformable body. After the substrate mixed emulsion is solidified, a stretchable substrate layer with a smooth surface is formed, and the thickness of the stretchable substrate layer is controlled to be 400 μm;

[0093] (3) mixing phenolic resin, propylene glycol, rosin tackifier, diacetone alcohol, and zinc dialkyl dithiophosphate evenly to prepare a temporary bonding adhesive solution, and then spin-coating the temporary bonding adhesive solution onto the surface of the stretchable substrate layer, and forming a temporary bonding adhesive layer after curing, and controlling the thickness of the temporary bonding adhesive layer to be 250 μm;

[0094] (4) A polyethylene film with a thickness of 150 μm is bonded to the surface of the temporary bonding adhesive layer, and pressure is applied to the plane of the polyethylene film to solidify it, thereby obtaining a protective film layer and obtaining a regional flexible stretch film.

[0095] Example 2

[0096] A zoned flexible stretch film comprises, from top to bottom, a protective film layer, a temporary bonding adhesive layer, and a stretchable substrate layer, wherein a linear elastic deformable body is embedded in the stretchable substrate layer, and the linear elastic deformable body is composed of a plurality of polymer elastic columns, wherein the arrangement structure of the plurality of polymer elastic columns is a grid-like arrangement structure, and the plurality of polymer elastic columns are integrally formed;

[0097] Among them, the protective film layer is a polyethylene film with a thickness of 150μm;

[0098] The raw materials of the temporary bonding layer are composed of resin (phenolic resin 40g), solvent (styrene 60g), tackifier (maleic rosin 9g), leveling agent (diacetone alcohol 0.07g), antioxidant (dialkyl dithiophosphate zinc 0.5g), and the thickness of the temporary bonding layer is 200μm;

[0099] The raw material of the stretchable substrate layer consists of 30 g of thermoplastic polyurethane and 8 g of polyolefin elastomer, the raw material of the linear elastic deformation body consists of 8 g of butyl rubber, and the thickness of the stretchable substrate layer is 400 μm.

[0100] The method for preparing a regional flexible stretch film comprises the following steps:

[0101] (1) pouring a curable butyl rubber emulsion into a mold having a grid-like arrangement structure, and after the butyl rubber emulsion is cured, a linear elastic deformable body having a grid-like arrangement structure is obtained;

[0102] (2) According to the above formula, a thermoplastic polyurethane emulsion and a polyolefin elastomer emulsion are mixed evenly to obtain a substrate mixed emulsion, the casting mold on the surface of the linear elastic deformable body is removed, and the substrate mixed emulsion is spin-coated on the surface of the solidified linear elastic deformable body. After the substrate mixed emulsion is solidified, a stretchable substrate layer with a smooth surface is formed, and the thickness of the stretchable substrate layer is controlled to be 400 μm;

[0103] (3) according to the formula, phenolic resin, styrene, maleic rosin, diacetone alcohol, and zinc dialkyl dithiophosphate are uniformly mixed to prepare a temporary bonding adhesive solution, and then the temporary bonding adhesive solution is spin-coated on the surface of the flexible stretchable substrate layer, and a temporary bonding adhesive layer is formed after curing, and the thickness of the temporary bonding adhesive layer is controlled to be 200 μm;

[0104] (4) A polyethylene film with a thickness of 150 μm is bonded to the temporary bonding adhesive layer, and pressure is applied to the plane of the polyethylene film to solidify it, and the solidified protective film layer is peeled off and fluorinated to obtain a regional flexible stretch film.

[0105] Specifically, the regional flexible stretch film prepared in Example 1 is applied to the mass transfer of Micro-LEDs. First, the protective film layer of the regional flexible stretch film is torn off and then the Micro-LED chips are bonded to the temporary bonding layer in an array, such as Figure 2 As shown, the Micro-LED chip is divided into uniform square areas by a regional flexible stretch film.

[0106] After the regional flexible stretch film is stretched transversely, Figure 3 As shown, after transverse stretching, the spacing between Micro-LED chips on the flexible stretch film in different regions becomes larger and remains consistent, while the longitudinal spacing between the chips remains unchanged;

[0107] The above-mentioned regional flexible stretch film is longitudinally stretched, and the results are as follows Figure 4 As shown, the longitudinal spacing increases after stretching, and the longitudinal spacing remains consistent. After horizontal and longitudinal stretching, the spacing between Micro-LED chips increases and remains consistent.

[0108] The technical principle of the present invention is described above in conjunction with specific embodiments. These descriptions are only for explaining the principle of the present invention and cannot be interpreted as limiting the scope of protection of the present invention in any way. Based on the explanations herein, those skilled in the art can associate other specific implementations of the present invention without paying creative labor, and these methods will fall within the scope of protection of the present invention.

Claims

1. A regional flexible stretch film, characterized in that: The invention comprises a protective film layer, a temporary bonding adhesive layer and a stretchable substrate layer in order from top to bottom, wherein a linear elastic deformable body is embedded in the stretchable substrate layer, and the linear elastic deformable body is composed of a plurality of polymer elastic columns, and the arrangement structure of the plurality of polymer elastic columns is any one of a horizontal linear arrangement, a vertical linear arrangement and a grid arrangement; The raw material of the polymer elastic column is a polymer elastic material; The material properties of the stretchable substrate layer and the linear elastic deformable body satisfy the following relationship: E2πd 2 =(4~400)E1LT; In the above relationship, E2 is the elastic modulus of the linear elastic deformer, d is the diameter of the polymer elastic column, E1 is the elastic modulus of the stretchable substrate layer, L is the original width of two adjacent polymer elastic columns, T is the original thickness of the regional flexible stretch film, and the value of π is 3.1416.

2. The regional flexible stretch film according to claim 1, characterized in that: The raw materials of the stretchable substrate layer are composed of thermoplastic polyurethane and polyolefin elastomer. In the total raw materials used for the stretchable substrate layer and the linear elastic deformer, the mass ratio of the thermoplastic polyurethane, the polyolefin elastomer and the polymer elastic material is (2-3): (0.5-1): (0.5-0.8).

3. The regional flexible stretch film according to claim 1, characterized in that: The polymer elastic material is selected from any one or more combinations of styrene-butadiene rubber, butyl rubber, silicone rubber and polydimethylsiloxane.

4. The regional flexible stretch film according to claim 1, characterized in that: In terms of mass percentage, the raw materials of the temporary bonding adhesive layer include 30-50 parts of resin, 50-70 parts of solvent, 9-11 parts of tackifier, 0.06-0.08 parts of leveling agent and 0.02-1 parts of antioxidant.

5. The regional flexible stretch film according to claim 4, characterized in that: The thermal decomposition temperature of the resin in the temporary bonding adhesive layer is ≥320°C.

6. The regional flexible stretch film according to claim 5, characterized in that: The resin in the temporary bonding adhesive layer is a network polymer formed by polycondensation reaction of polyalkyl acrylate and / or diamine compound with aliphatic aldehyde, or a synthetic resin.

7. The regional flexible stretch film according to claim 1, characterized in that: The thickness of the protective film layer is 100 μm to 150 μm; The thickness of the temporary bonding adhesive layer is 200 μm to 350 μm; The thickness of the stretchable substrate layer is 300 μm to 400 μm.

8. The regional flexible stretch film according to claim 1, characterized in that: The regional flexible stretch film is used in array expansion.

9. The regional flexible stretch film according to claim 1, characterized in that: The regional flexible stretch film is used in the mass transfer of Micro-LEDs.

10. A method for preparing a regional flexible stretch film, characterized in that: The method for preparing the regional flexible stretch film according to any one of claims 1 to 9 comprises the following steps: (1) pouring a polymer elastic material into a mold, and after the polymer elastic material is cured, a linear elastic deformable body having a structure corresponding to the mold is obtained, and the mold has any one of a transverse linear arrangement structure, a longitudinal linear arrangement structure, and a grid arrangement structure; (2) mixing thermoplastic polyurethane and polyolefin elastomer to prepare a substrate mixed emulsion; after the linear elastic deformable body is separated from the mold, the mixed emulsion is spin-coated on the surface of the linear elastic deformable body, and after curing, a stretchable substrate layer is formed; (3) spin coating a temporary bonding adhesive solution on the surface of the stretchable substrate layer to form a temporary bonding adhesive layer after curing; (4) Bonding the protective film to the temporary bonding adhesive layer to form a protective film layer on the surface of the temporary bonding adhesive layer, and applying pressure to the protective film layer to obtain a regional flexible stretch film.

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