Pressure-sensitive adhesive composition and pressure-sensitive adhesive tape

Abstract

The present application provides a kind of pressure sensitive adhesive composition and pressure sensitive adhesive tape, belong to adhesive technical field.The pressure sensitive adhesive composition of the present application includes core-shell filler, the core-shell filler includes core and shell, the core is phase change material with melting point of 60-120 ℃, the shell is formed by photothermal material nanoparticles;The photothermal material nanoparticles are dispersed and loaded on the outer surface of the phase change material;In the core-shell filler, the mass ratio of photothermal material and phase change material is 1: (1.5-5.6) ;The pressure sensitive adhesive tape of the present application includes adhesive layer formed by the pressure sensitive adhesive composition of the present application by curing.The pressure sensitive adhesive tape of the present application can realize initial bonding firm, near-infrared light irradiation rapid trigger failure, low peeling force and no residue, reduce the damage to the overall glue layer, and can realize multiple repair.

Description

Technical Field

[0001] This invention relates to the field of adhesive technology, and more particularly to a pressure-sensitive adhesive composition and a pressure-sensitive adhesive tape. Background Technology

[0002] Current photovoltaic positioning tapes mostly use conventional high-temperature pressure-sensitive adhesive systems, which have fixed and irreversible adhesion, resulting in common assembly defects such as misalignment of cell strings, microcracks in cells, and misalignment of solder ribbons. During rework, adhesive residue is easily left behind and the tape itself is torn when peeled off, which not only renders the tape unusable but also easily scratches the grid lines on the surface of the cells, damages the encapsulation film (such as POE film), and may even cause internal short circuits in the module, seriously affecting the module yield.

[0003] Patent CN119119891A discloses a positioning tape whose adhesive layer is made of polyethylene glycol oligomer containing tert-butyloxycarbonyl groups. When photovoltaic modules require repair, the adhesive layer can be quickly de-adhesiveted by heating with an infrared lamp, making repair easier and preventing more cells from breaking when the positioning tape is removed. However, this positioning tape can only be used for one repair, which may not meet the needs of most practical applications. Patents EP1233036B1, US6828023B2, and EP2626390B1, among others, have studied pressure-sensitive adhesive tapes containing thermally expanding microspheres and their application in solar cell modules. However, this method requires overall heating (which may damage heat-sensitive elements), has high energy consumption, slow response speed, and a steep peel force curve that may cause components to suddenly bounce off. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a pressure-sensitive adhesive composition and a pressure-sensitive adhesive tape. The pressure-sensitive adhesive tape is easy to peel off after light exposure, and its adhesiveness can be restored after peeling. The pressure-sensitive adhesive tape can be repeatedly peeled off and its adhesiveness restored at least twice.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a pressure-sensitive adhesive composition comprising a core-shell filler, the core-shell filler comprising a core and a shell, the core being a phase change material with a melting point of 60-120°C, and the shell being formed of photothermal material nanoparticles; the photothermal material nanoparticles being dispersed and loaded on the outer surface of the phase change material; and in the core-shell filler, the mass ratio of the photothermal material to the phase change material being 1:(1.5-5.6).

[0006] The pressure-sensitive adhesive composition of this invention employs a core-shell filler, which uses a phase change material as the core and a photothermal material as the shell. When exposed to near-infrared light (e.g., near-infrared laser or LED light source with wavelengths of 808nm or 980nm), the shell generates heat, which is rapidly transferred to the core. The core melts upon heating, and the core-shell filler undergoes phase change slip. This phase change slip reduces the adhesive strength, allowing for easy peeling without residue. After being protected from light, the core solidifies, thus restoring the adhesive tape's tackiness. Therefore, pressure-sensitive tapes containing the pressure-sensitive adhesive composition of this invention achieve strong initial adhesion, rapid failure triggered by near-infrared light irradiation, low peel strength, and no residue, making them suitable for temporary positioning and rework in precision electronic assemblies (such as chips, displays, and sensors).

[0007] More importantly, core-shell fillers can achieve efficient, localized phase change, reducing thermal damage to the overall adhesive layer. The ratio of photothermal material to phase change material significantly affects the performance of pressure-sensitive adhesive tapes made from the adhesive composition. For example, it influences the peel strength under light exposure, the degree of tack recovery when protected from light, and the number of peel-off repairs required. Studies show that when the mass ratio of photothermal material to phase change material is 1:(1.5-5.6), the pressure-sensitive tape exhibits low peel strength under light exposure, good tack when protected from light, and can achieve at least two repeated peel-off and tack recovery repairs, far superior to existing positioning tapes that can only undergo one repair.

[0008] In some embodiments, the core-shell filler is present in the pressure-sensitive adhesive composition at a weight percentage of 18.8%-28.2%.

[0009] In some preferred embodiments, the mass ratio of photothermal material to phase change material in the core-shell filler is 1:(3.5-4.3). Under these conditions, the pressure-sensitive tape exhibits low peel strength when exposed to light, good adhesion when protected from light, and can achieve repeated peel-and-adhesion recovery (rework) up to 3 times or more.

[0010] In some embodiments, the core is a phase change material microsphere with a melting point of 95-115°C. Preferably, the phase change material is a gallium-indium alloy, wherein the mass percentage of indium in the gallium-indium alloy is 50%-70%.

[0011] In some embodiments, the photothermal material nanoparticles contain at least one of CuS, MoO3, Fe3O4, Ti2O3, and black TiO2.

[0012] In some embodiments, the phase change material is a gallium-indium alloy, wherein the mass percentage of indium in the gallium-indium alloy is 50%-70%, and the photothermal material is CuS.

[0013] In some embodiments, the particle size D90 of the core-shell packing is 500-1000 nm, preferably 600-800 nm.

[0014] In some embodiments, the method for preparing the core-shell packing includes the following steps: Molten phase change material is injected into hot oil or polymer solution containing surfactant under a protective atmosphere, sheared and emulsified, and then quenched to obtain phase change material microspheres. Acid etching was performed on the surface of the phase change material microspheres; Photothermal material nanoparticles are loaded onto the surface of phase change material microspheres after acid etching at a temperature below the melting point of the phase change material.

[0015] In the above preparation method, acid etching of the surface of the phase change material microspheres can increase surface activity and binding sites.

[0016] In some embodiments, the photothermal material is CuS. The method for loading photothermal material nanoparticles onto the surface of acid-etched phase change material microspheres involves mixing the acid-etched phase change material microspheres with a copper source and a sulfur source, and reacting the mixture at a temperature below the melting point of the phase change material. After the reaction, CuS nanoparticles directly nucleate and grow heterogeneously on the surface of the microspheres, dispersing and loading onto the surface of the phase change material microspheres to form a non-completely continuous shell.

[0017] The pressure-sensitive adhesive composition of the present invention can be an acrylic pressure-sensitive adhesive composition. For example, in some embodiments, the pressure-sensitive adhesive composition comprises the following components in parts by weight: 30-37 parts of soft monomer, 10-13 parts of hard monomer, 1-2 parts of functional monomer, 44-48 parts of solvent, 0.1-0.2 parts of initiator, and 20-40 parts of the core-shell filler. In some embodiments, the core-shell filler is 23-34 parts by weight.

[0018] The aforementioned soft monomers refer to monomers with a glass transition temperature (Tg) below -20°C. Their function is to provide molecular chain flexibility, making the adhesive layer viscoelastic at room temperature and able to quickly wet the surface of the adhered objects. Hard monomers are monomers with a glass transition temperature (Tg) above 50°C; they are used to improve the cohesive strength and tack of pressure-sensitive adhesives. Functional monomers are polymerizable monomers containing active functional groups (such as carboxyl, hydroxyl, epoxy, amino, amide, etc.) and are used to achieve polymer crosslinking or improve interfacial adhesion. Soft monomers, hard monomers, and functional monomers can be selected based on existing technology and conventional knowledge.

[0019] In some embodiments, the soft monomer is selected from at least one of butyl acrylate (BA), 2-ethylhexyl acrylate (2-EHA), isooctyl acrylate (IOA), ethyl acrylate, lauryl acrylate, and octadecyl acrylate.

[0020] In some embodiments, the hard monomer is selected from at least one of methyl methacrylate (MMA), vinyl acetate (VAc), and styrene (St).

[0021] In some embodiments, the functional monomer is selected from at least one of hydroxyethyl acrylate (HEA), hydroxypropyl acrylate (HPA), acrylic acid (AA), methacrylic acid (MAA), N-vinylpyrrolidone (NVP), and acrylamide (AM).

[0022] In some embodiments, the solvent is selected from at least one of ethyl acetate, toluene, and acetone.

[0023] In some embodiments, the initiator is selected from at least one of azobisisobutyronitrile (AIBN), benzoyl peroxide (BPO), ammonium persulfate (APS), potassium persulfate (KPS), benzoyl ether, and benzophenone.

[0024] In some embodiments, the pressure-sensitive adhesive composition further includes 0.5-1 parts by weight of tackifying resin and / or 0.3-0.5 parts by weight of other additives.

[0025] In some embodiments, the tackifying resin is selected from at least one of petroleum resin (C5 / C9), rosin resin, and terpene resin.

[0026] In some embodiments, the other additives include at least one of antioxidants and plasticizers. Preferably, the antioxidant is a hindered phenolic antioxidant and / or an aromatic amine antioxidant.

[0027] The pressure-sensitive adhesive composition of the present invention is prepared by mixing its components in a specified ratio.

[0028] In a second aspect, the present invention provides a pressure-sensitive adhesive tape comprising an adhesive layer formed by curing the aforementioned pressure-sensitive adhesive composition.

[0029] When the pressure-sensitive tape of this invention is irradiated with near-infrared light, photothermal effects cause a phase transition and slippage in the core-shell filler, thus reducing its adhesion and enabling rework. More importantly, the pressure-sensitive tape of this invention can be reworked at least twice.

[0030] In some embodiments, the thickness of the adhesive layer is 25-50 μm.

[0031] In some embodiments, the pressure-sensitive tape further includes a substrate layer and a release film layer, wherein the substrate layer, adhesive layer and release film layer are arranged sequentially from bottom to top.

[0032] In some embodiments, the substrate layer is made of at least one of polyethylene terephthalate (PET), polypropylene (PP), polyimide (PI), polytetrafluoroethylene (PTFE), and perfluoroalkoxy resin (PFA).

[0033] In some embodiments, the thickness of the substrate layer is 100-200 μm.

[0034] In some embodiments, the release film layer is a double-sided release film.

[0035] In some embodiments, the thickness of the release film is 50 μm.

[0036] Compared with the prior art, the beneficial effects of the present invention are as follows: The pressure-sensitive adhesive composition of this invention employs a core-shell filler with a phase change material as the core and a photothermal material as the shell. When a pressure-sensitive tape containing this composition is irradiated with near-infrared light, the heat generated by the photothermal effect first melts the core alloy, achieving phase change slip. Phase change slip reduces the adhesive strength of the pressure-sensitive tape adhesive layer, making it easy to peel off without leaving any residue. Furthermore, the core-shell structure of the filler ensures that heat is generated in the shell layer and quickly transferred to the core layer, achieving efficient and localized phase change, reducing damage to the overall adhesive layer, and enabling multiple rework. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0038] Figure 1 This is a schematic diagram of the structure of the pressure-sensitive adhesive tape of the present invention.

[0039] Figure label: 1: Substrate layer; 2: Adhesive layer; 3: Release film layer. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0041] The preferred embodiments and comparative examples of the present invention will be described below. However, the following embodiments are merely preferred embodiments of the present invention, and the present invention is not limited to the following embodiments.

[0042] The sources or preparation methods of the substances involved in the examples are as follows: A1-A9: CuS-gallium indium alloy core-shell filler; A10: MoO3-gallium indium alloy core-shell filler; A11: Fe3O4-gallium indium alloy core-shell filler.

[0043] The specific preparation steps of the CuS-gallium indium alloy core-shell filler are as follows: (1) Preparation of solid low melting point alloy microspheres: Select gallium indium alloy (melting point between 60-120 degrees Celsius), inject molten gallium indium alloy into hot oil or polymer solution containing surfactant (such as polyvinyl alcohol or polyacrylic acid block copolymer) under a protective atmosphere, emulsify by high-speed shearing, and then quickly pour into a cold bath for quenching to obtain solid alloy microspheres; (2) Surface pretreatment of solid alloy microspheres: acid etching of the surface of solid alloy microspheres to increase surface activity and binding sites; (3) Loading CuS nanoparticles on the surface of solid microspheres: The pretreated alloy microspheres are added to the reactor along with copper and sulfur sources and reacted at a low temperature (below the melting point of gallium indium alloy) to allow CuS nanoparticles to grow heterogeneously on the surface of the microspheres, resulting in a core-shell filler with solid gallium indium alloy as the core and CuS nanoparticles tightly attached / embedded on the surface.

[0044] The difference between the specific preparation steps of MoO3-gallium indium alloy core-shell filler and CuS-gallium indium alloy core-shell filler is that step (3) involves loading MoO3 nanoparticles onto the surface of solid microspheres: the pretreated alloy microspheres and MoO3 are added together to the reactor and reacted at a lower temperature (below the melting point of gallium indium alloy) so that the MoO3 nanoparticles can grow heterogeneously on the surface of the microspheres, thus obtaining a core-shell filler with solid gallium indium alloy as the core and MoO3 nanoparticles tightly attached / embedded on the surface.

[0045] The specific preparation steps of Fe3O4-gallium indium alloy core-shell filler differ from those of CuS-gallium indium alloy core-shell filler only in that step (3) involves loading Fe3O4 nanoparticles onto the surface of solid microspheres: the pretreated alloy microspheres and Fe3O4 are added together to the reactor and reacted at a lower temperature (below the melting point of gallium indium alloy) so that Fe3O4 nanoparticles can grow heterogeneously on the surface of the microspheres, thus obtaining a core-shell filler with solid gallium indium alloy as the core and Fe3O4 nanoparticles tightly attached / embedded on the surface.

[0046] The characterization methods for the melting point, particle size, and filler morphology of the substances prepared by the above method are as follows: The melting point was characterized using DSC, and the test steps were as follows: approximately 5 mg of sample was placed in a crucible, the crucible lid was closed, and the crucible was placed in the instrument; the test conditions were set, and the temperature was raised to 300 degrees Celsius for testing; the experimental curve was analyzed to determine the melting point. Particle size was analyzed using dynamic light scattering. The specific steps are as follows: the sample particles were uniformly dispersed in a solvent of appropriate concentration, placed in a cuvette, and the sample was tested and the data was analyzed to obtain the particle size D90 of the sample. The morphology of the filler was tested using TEM. The specific testing steps are as follows: Dissolve the sample in a solvent, take a drop and place it on a copper grid, wait overnight for the solvent to evaporate, and then perform the test to obtain a TEM image of the filler.

[0047] The substances represented by A1-A11 are as follows: A1-A9: CuS-GaIn alloy core-shell fillers. These fillers consist of a core and a shell. The core is a GaIn alloy microsphere, and the shell is formed by CuS nanoparticles dispersed and loaded on the outer surface of the GaIn alloy microspheres. The specific CuS-GaIn alloy core-shell fillers are as follows: A1: The mass percentage of indium in the gallium-indium alloy is 60%, and its melting point is 105℃; in the CuS-gallium-indium alloy core-shell filler, the mass ratio of CuS to gallium-indium alloy is 1:4, and the particle size D90 of the CuS-gallium-indium alloy core-shell filler is 800nm. A2: The mass percentage of indium in the gallium-indium alloy is 60%, and its melting point is 105℃; in the CuS-gallium-indium alloy core-shell filler, the mass ratio of CuS to gallium-indium alloy is 1:3.5, and the particle size D90 of the CuS-gallium-indium alloy core-shell filler is 800nm. A3: The mass percentage of indium in the gallium-indium alloy is 60%, and its melting point is 105℃; in the CuS-gallium-indium alloy core-shell filler, the mass ratio of CuS to gallium-indium alloy is 1:4.3, and the particle size D90 of the CuS-gallium-indium alloy core-shell filler is 800nm. A4: The mass percentage of indium in the gallium-indium alloy is 60%, and its melting point is 105℃; in the CuS-gallium-indium alloy core-shell filler, the mass ratio of CuS to gallium-indium alloy is 1:1.5, and the particle size D90 of the CuS-gallium-indium alloy core-shell filler is 800nm. A5: The mass percentage of indium in the gallium-indium alloy is 60%, and its melting point is 105℃; in the CuS-gallium-indium alloy core-shell filler, the mass ratio of CuS to gallium-indium alloy is 1:5.6, and the particle size D90 of the CuS-gallium-indium alloy core-shell filler is 800nm. A6: The mass percentage of indium in the gallium-indium alloy is 50%, and its melting point is 95℃; in the CuS-gallium-indium alloy core-shell filler, the mass ratio of CuS to gallium-indium alloy is 1:4, and the particle size D90 of the CuS-gallium-indium alloy core-shell filler is 600nm. A7: The mass percentage of indium in the gallium-indium alloy is 70%, and its melting point is 115℃; in the CuS-gallium-indium alloy core-shell filler, the mass ratio of CuS to gallium-indium alloy is 1:4, and the particle size D90 of the CuS-gallium-indium alloy core-shell filler is 600nm. A8: The mass percentage of indium in the gallium-indium alloy is 30%, and its melting point is 139℃; in the CuS-gallium-indium alloy core-shell filler, the mass ratio of CuS to gallium-indium alloy is 1:4, and the particle size D90 of the CuS-gallium-indium alloy core-shell filler is 800nm. A9: The mass percentage of indium in the gallium-indium alloy is 60%, and its melting point is 105℃; in the CuS-gallium-indium alloy core-shell filler, the mass ratio of CuS to gallium-indium alloy is 1:14, and the particle size D90 of the CuS-gallium-indium alloy filler is 800nm. A10: MoO3-GaIn alloy core-shell filler. The MoO3-GaIn alloy core-shell filler consists of a core and a shell. The core is a GaIn alloy microsphere, and the shell is formed by MoO3 nanoparticles dispersed and loaded on the outer surface of the GaIn alloy microspheres. The mass percentage of indium in the GaIn alloy is 60%, and its melting point is 105℃. In the MoO3-GaIn alloy core-shell filler, the mass ratio of MoO3 to GaIn alloy is 1:2, and the particle size D90 of the MoO3-GaIn alloy core-shell filler is 800 nm. A11: Fe3O4-GaIn alloy core-shell filler. The Fe3O4-GaIn alloy core-shell filler consists of a core and a shell. The core is a GaIn alloy microsphere, and the shell is formed by Fe3O4 nanoparticles dispersed and loaded on the outer surface of the GaIn alloy microspheres. The mass percentage of indium in the GaIn alloy is 60%, and its melting point is 105℃. In the Fe3O4-GaIn alloy core-shell filler, the mass ratio of Fe3O4 to GaIn alloy is 1:2, and the particle size D90 of the Fe3O4-GaIn alloy core-shell filler is 800 nm.

[0048] B1 (soft monomer): butyl acrylate; B2 (soft monomer): Octadecyl acrylate; C1 (hard monomer): methyl methacrylate; C2 (hard monomer): vinyl acetate; D1 (functional monomer): hydroxyethyl acrylate; D2 (functional monomer): acrylic acid; E1 (solvent): Ethyl acetate; E2 (solvent): Acetone; F1 (initiator): Azobisisobutyronitrile (AIBN); F2 (initiator): Benzoyl peroxide; G1 (Tackifying Resin): Petroleum resin; G2 (Tackifying Resin): Rosin resin; H1 (antioxidants): Aromatic amine antioxidants; H2 (antioxidant): Hindered phenolic antioxidant.

[0049] Examples 1-13 and Comparative Examples 1-4 The compositions of the pressure-sensitive adhesive compositions of Examples 1-13 and Comparative Examples 1-4 are shown in Table 1 below.

[0050] Table 1

[0051] In the table above, "—" indicates that the substance is not present.

[0052] The specific preparation steps of the pressure-sensitive adhesive compositions in the above embodiments and Comparative Examples 1 and 2 are as follows: (1) Pretreatment of pressure-sensitive adhesive matrix: Mix soft monomers, hard monomers, functional monomers, solvents and initiators in proportion to obtain pressure-sensitive adhesive matrix; Place the pressure-sensitive adhesive matrix in a constant temperature water bath (40±2℃) and stir for 30min (stirring speed 300r / min) to homogenize the pressure-sensitive adhesive matrix and remove internal air bubbles; If there are impurities in the pressure-sensitive adhesive matrix, filter it with a 1000 mesh filter to avoid impurities affecting the smoothness of the adhesive layer; (2) Mixing pressure-sensitive adhesive matrix and auxiliary materials: Slowly add tackifier and antioxidant to the pretreated pressure-sensitive adhesive matrix, and then put it into a constant temperature water bath (40±2℃) and stir at 500r / min for 20min to ensure that the auxiliary materials are evenly dispersed in the pressure-sensitive adhesive matrix without local agglomeration, and obtain a mixed system; (3) Adding and mixing the core-shell filler: slowly pour the core-shell filler into the mixture prepared in step (2) while stirring at 300 r / min to avoid microsphere agglomeration; after pouring, increase the stirring speed to 400 r / min and continue stirring for 30 min. After stirring, use a laser particle size analyzer to detect the dispersibility of the filler to ensure that the microsphere particle size distribution is uniform (≥95% in the range of 100-200 nm) and obtain the pressure-sensitive adhesive composition.

[0053] The method for testing the dispersibility of fillers is as follows: ① Background Measurement: Inject sufficient degassed pure dispersion medium into a clean sample cell. Start circulation and ultrasonication (intensity initially set to low) to ensure the medium is homogeneous and free of air bubbles. Perform "Background Measurement," and the instrument will record the light scattering signal of the medium itself as the background. ② Take a small amount of sample and put it into a beaker. Sonicate it in an ultrasonic cleaner for 2-5 minutes (adjust according to the degree of aggregation). ③ Add the well-dispersed suspension drop by drop into the circulating sample cell, while observing the concentration (blocking rate / transmittance) displayed on the instrument in real time. Once the appropriate concentration is reached, stop adding the sample and allow the circulation system to run stably for about 30 seconds. ④ Conduct sample testing. Each sample is usually tested three times, and then the data is recorded.

[0054] The only difference between the pressure-sensitive adhesive composition of Comparative Example 3 and the preparation methods of the pressure-sensitive adhesive compositions of Comparative Examples 1 and 2 is that the preparation method of Comparative Example 3 does not include the above step (3), and the mixed system prepared in step (2) is the pressure-sensitive adhesive composition of Comparative Example 3.

[0055] The only difference between the pressure-sensitive adhesive composition of Comparative Example 4 and the preparation methods of the pressure-sensitive adhesive compositions of the above embodiments and Comparative Examples 1 and 2 is that step (3) of Comparative Example 4 is to directly mix CuS and gallium indium alloy and add them to the mixed system prepared in step (2) to obtain the pressure-sensitive adhesive composition of Comparative Example 4.

[0056] Furthermore, pressure-sensitive adhesive compositions prepared in each embodiment and comparative example were used as raw materials to prepare pressure-sensitive adhesive tapes. The preparation method of the pressure-sensitive adhesive tapes is as follows: (1) Adhesive coating: Each pressure-sensitive adhesive composition is coated onto the PET substrate by doctor blade coating or wire bar coating, and the dry film thickness is controlled to be 30 micrometers according to the solid content; (2) Adhesive layer curing and rewinding: The substrate after coating treatment in step (1) is placed in an oven at 150-180 degrees Celsius and cured for 3-5 minutes. Then, it is coated with release film on a laminating machine to prepare pressure-sensitive tape.

[0057] The structure of the obtained pressure-sensitive tape is as follows Figure 1 As shown, it includes a substrate layer 1, an adhesive layer 2, and a release film layer 3 arranged sequentially from bottom to top.

[0058] Apply pressure-sensitive tape to the part that needs positioning. If rework is required, irradiate the tape area for several seconds to tens of seconds using a near-infrared laser or LED light source with a specific wavelength (such as 808nm, 980nm). After irradiation, the part and tape can be easily and manually removed without damage.

[0059] Performance testing: The performance of pressure-sensitive adhesive tapes prepared from the pressure-sensitive adhesive compositions of Examples 1-13 and Comparative Examples 1-4 were tested respectively. The test methods are as follows (1)-(4).

[0060] (1) Peel force at stability: Apply the pressure-sensitive adhesive tape (1cm wide) flat onto the battery cell, and roll it back and forth 2-3 times at a constant speed with a standard pressure roller (such as a 2kg rubber roller) to ensure no air bubbles and complete adhesion. Clamp the test plate in the lower fixture of the testing machine. Fold the free end of the pressure-sensitive adhesive tape back at a 180° angle and clamp it in the upper fixture. Ensure that the peel angle remains constant throughout the process. Record the average force value of the stable section, which is the peel force we need.

[0061] (2) Initial and Aging Color Values: The pressure-sensitive tape was prepared into a laminate, with the specific structure from bottom to top being glass, EVA film, pressure-sensitive tape, EVA film, and glass. The initial, PCT-aged, and UV-aged color values ​​of the samples were tested using a spectrophotometer. Sample preparation required a clean, flat, scratch-free, and contamination-free surface. The instrument was adjusted using a d / 8° integrating sphere and incandescent light.

[0062] The specific testing method is as follows: use the included whiteboard and blackboard (or standard tiles) to perform zero-point calibration and white calibration; measure and save the color data of the standard sample as a reference, and finally test the sample.

[0063] (3) Triggering peel test: The finished adhesive layer (1cm wide) is pasted on the smooth surface of the cell (pasting pressure 0.4MPa, stand for 30min to ensure tight adhesion and no air bubbles). A near-infrared laser or LED light source with a specific wavelength (such as 808nm, 980nm) is used to irradiate the pressure-sensitive tape area for about 10 seconds to ensure that the core and shell filler fully undergo phase change shrinkage. Then the test piece is taken out and a 180° peel test is immediately performed using a tensile testing machine. The peeling speed is controlled at 300mm / min and the peeling strength needs to be reduced to 0.3-0.8N / 25mm to see if it can be easily peeled without damage. After peeling, there is no residual adhesive on the surface of the cell (residual adhesive area ≤1%), and the adhesive layer is undamaged and does not delaminate.

[0064] (4) Adhesive recovery test: After peeling, the adhesive layer is left to stand at room temperature (25℃) for 10 minutes, and then it is pasted on the smooth surface of the battery cell again. The 180° peel strength is tested and it needs to be restored to 2.0-3.0N / 25mm to meet the repositioning requirements. Repeat the peel-adhesive recovery test 3 times and there is no significant performance degradation (peel strength deviation ≤0.3N / 25mm).

[0065] The performance test results are shown in Table 2 below.

[0066] Table 2

[0067] As shown in Table 2, in the core-shell filler used in this invention, the melting point of the phase change material and the ratio of the phase change material to the photothermal material all affect the performance of the pressure-sensitive adhesive tape. For example, it affects whether peeling is triggered when exposed to light, the degree of recovery of adhesion when protected from light, and whether it can be reworked and the number of rework cycles. Furthermore, changes in the ratio of the pressure-sensitive adhesive composition of this invention will affect the adhesion and color of the pressure-sensitive adhesive tape.

[0068] 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 of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A pressure-sensitive adhesive composition, characterized in that, The material includes a core-shell packing, which comprises a core and a shell. The core is a phase change material with a melting point of 60-120℃, and the shell is formed of photothermal material nanoparticles. The photothermal material nanoparticles are dispersed and loaded on the outer surface of the phase change material. In the core-shell packing, the mass ratio of photothermal material to phase change material is 1:(1.5-5.6).

2. The pressure-sensitive adhesive composition according to claim 1, characterized in that, The core-shell filler is present in the pressure-sensitive adhesive composition at a weight percentage of 18.8%-28.2%.

3. The pressure-sensitive adhesive composition according to claim 1 or 2, characterized in that, In the core-shell packing material, the mass ratio of photothermal material to phase change material is 1:(3.5-4.3).

4. The pressure-sensitive adhesive composition according to any one of claims 1-3, characterized in that, The core is a phase change material microsphere with a melting point of 95-115℃; preferably, the phase change material is a gallium-indium alloy, wherein the mass percentage of indium in the gallium-indium alloy is 50%-70%. And / or, in the photothermal material nanoparticles, the photothermal material is at least one of CuS, MoO3, Fe3O4, Ti2O3, and black TiO2.

5. The pressure-sensitive adhesive composition according to any one of claims 1-4, characterized in that, The particle size D90 of the core-shell packing is 500-1000 nm.

6. The pressure-sensitive adhesive composition according to any one of claims 1-5, characterized in that, It comprises the following components in parts by weight: 30-37 parts soft monomer, 10-13 parts hard monomer, 1-2 parts functional monomer, 44-48 parts solvent, 0.1-0.2 parts initiator, and 20-40 parts of the core-shell filler; Preferably, the pressure-sensitive adhesive composition satisfies at least one of the following (I)-(V): (I) The soft monomer is selected from at least one of butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, ethyl acrylate, lauryl acrylate, and octadecyl acrylate; (II) The hard monomer is selected from at least one of methyl methacrylate, vinyl acetate, and styrene; (III) The functional monomer is selected from at least one of hydroxyethyl acrylate, hydroxypropyl acrylate, acrylic acid, methacrylic acid, N-vinylpyrrolidone, and acrylamide; (IV) The solvent is selected from at least one of ethyl acetate, toluene, and acetone; (V) The initiator is selected from at least one of azobisisobutyronitrile, benzoyl peroxide, ammonium persulfate, potassium persulfate, benzoyl ether, and benzophenone.

7. The pressure-sensitive adhesive composition according to claim 6, characterized in that, It also includes 0.5-1 parts by weight of tackifying resin and / or 0.3-0.5 parts by weight of other additives; Preferably, the tackifying resin is selected from at least one of petroleum resin, rosin resin, and terpene resin; and / or, the other additives include at least one of antioxidants and plasticizers.

8. A pressure-sensitive adhesive tape, characterized in that, It includes an adhesive layer, which is formed by curing the pressure-sensitive adhesive composition according to any one of claims 1-7.

9. The pressure-sensitive tape according to claim 8, characterized in that, The thickness of the adhesive layer is 25-50 μm.

10. The pressure-sensitive tape according to claim 8 or 9, characterized in that, It also includes a substrate layer and a release film layer, wherein the substrate layer, adhesive layer and release film layer are arranged sequentially from bottom to top; Preferably, the substrate layer is made of at least one of polyethylene terephthalate, polypropylene, polyimide, polytetrafluoroethylene, and perfluoroalkoxy resin. Preferably, the thickness of the substrate layer is 100-200 μm; and / or, the thickness of the release film layer is 50 μm.

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