Adhesive film, method for manufacturing the same, composite assembly, and electronic device

Abstract

The application provides an adhesive film, a preparation method of the adhesive film, a composite assembly and an electronic device. The adhesive film is prepared by cross-linking reaction of a prepolymer. The prepolymer comprises an alkyl acrylate soft monomer and an acrylate polar monomer. The mass percentage of the alkyl acrylate soft monomer in the prepolymer is greater than or equal to 60 wt%, and the mass percentage of the acrylate polar monomer in the prepolymer is less than 30 wt%. The adhesive film provided by the application has excellent low-temperature low modulus and high creep recovery rate, and can improve the service life of a foldable electronic device in a repeated folding process.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optically clear adhesive, in particular to an adhesive film, a preparation method thereof, a composite assembly and an electronic device. BACKGROUND

[0002] At present, the folding organic light-emitting diode (OLED) display screen needs to be attached to a polarizing plate, a transparent polyimide cover film and other multi-layer optical film materials on the top, which plays multiple roles such as preventing environmental light reflection and protecting the screen. The screen needs to be attached to a support film and a metal support layer on the bottom to provide support for the screen and prevent the screen from deforming too much when pressed, which leads to display failure. Various film materials of different materials are bonded together by optically clear adhesive (OCA).

[0003] Optically clear adhesive is a viscoelastic body that has adhesive force and viscoelastic properties at room temperature. The optically clear adhesive used in ordinary 2D or 3D display modules has high adhesive force, which can firmly bond the upper and lower interfaces to be bonded. In the process of bonding the folding display module, the upper and lower interfaces to be bonded need to be bonded together by OCA with high adhesive property.

[0004] However, in the process of bending, the upper and lower film materials will move relative to each other, and the amount of movement will gradually increase with the bending radius and the distance from the neutral layer. In the currently commonly used folding display module, the amount of movement of the upper and lower film layers can reach 3 times or more the thickness of the optically clear adhesive, which requires the optically clear adhesive OCA to have a relatively high creep recovery rate.

[0005] At present, the optically clear adhesive used in ordinary 2D or 3D display modules has high adhesive force and poor creep recovery rate, which cannot meet the use requirements of folding display modules. Moreover, in the process of bending the folding display module, the upper and lower film layers will be firmly bonded and cannot move due to the high cohesion of ordinary OCA, which is easy to cause damage to the folding display module. SUMMARY

[0006] In view of this, the present application provides an adhesive film, a preparation method thereof, a composite assembly and an electronic device, which has flexibility, low modulus at low temperature, excellent creep recovery rate characteristics, and can improve the service life of foldable electronic devices.

[0007] In a first aspect, the present application provides an adhesive film, which is prepared by cross-linking reaction of a prepolymer, the prepolymer comprising an alkyl acrylate soft monomer and an acrylate polar monomer; wherein the mass fraction of the alkyl acrylate soft monomer in the prepolymer is ≥ 60 wt%, and the mass fraction of the acrylate polar monomer in the prepolymer is < 30 wt%.

[0008] In the above solution, by adjusting the mass ratio of alkyl acrylate soft monomers to polar acrylate monomers, the wetting effect of the adhesive film can be improved, enhancing the interfacial adhesion of the adhesive film. Furthermore, the adhesive film exhibits excellent low-temperature low modulus and high creep recovery rate. This avoids the need for foldable electronic devices using this adhesive film to creep and recover with the misalignment between film materials during repeated folding, preventing the film materials from failing to move due to excessive adhesive force, thus extending the service life of foldable electronic devices.

[0009] In some embodiments, the prepolymer comprises an alkyl acrylate soft monomer as shown in formula (I).

[0010]

[0011] Wherein, R1 is independently selected from substituted or unsubstituted C1-C20 alkyl groups, and n1 is an integer greater than zero.

[0012] Specifically, the alkyl acrylate soft monomer can be at least one of the following: 2-ethylhexyl (meth)acrylate (abbreviated as 2-EHA), methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate (abbreviated as BA), isobutyl (meth)acrylate, n-pentyl (meth)acrylate, hexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, n-decyl (meth)acrylate, isodecyl (meth)acrylate, dodecyl (meth)acrylate, isooctyl (meth)acrylate, hexadecyl (meth)acrylate, and octadecyl (meth)acrylate.

[0013] In some embodiments, the prepolymer comprises an acrylate polar monomer as shown in formula (II) and / or an acrylate polar monomer as shown in formula (III);

[0014]

[0015] Wherein, R2 is independently selected from substituted or unsubstituted C1-C10 alkyl groups, and R3 is selected from at least one of hydroxyl, carboxyl, epoxy, and amino groups; n2 and n3 are integers greater than zero.

[0016] Specifically, the polar monomer of the acrylate can be any one of acrylic acid (abbreviated as AA), hydroxybutyl acrylate (abbreviated as 4HBA), hydroxyethyl acrylate (abbreviated as 2HEA), 2-hydroxypropyl acrylate (abbreviated as HPA), hydroxyethyl methacrylate (abbreviated as HEMA), and hydroxypropyl methacrylate (abbreviated as HPMA). Of course, it can also be other monomers having the structure shown in formula (II), which is not limited here.

[0017] In some embodiments, the alkyl acrylate soft monomer accounts for 60 wt% to 85 wt% of the prepolymer, and the acrylate polar monomer accounts for 10 wt% to 25 wt% of the prepolymer.

[0018] In some embodiments, the prepolymer comprises two alkyl acrylate soft monomers, wherein one of the alkyl acrylate soft monomers is selected from butyl acrylate, and the butyl acrylate accounts for 5 wt% to 20 wt% of the mass of the prepolymer.

[0019] In some embodiments, the weight-average molecular weight of the prepolymer is ≥600,000 Da.

[0020] Secondly, this application provides a method for preparing an adhesive film, the method comprising:

[0021] Under inert gas protection, alkyl acrylate soft monomers, acrylate polar monomers and solvents are mixed and a thermal initiator is added. The mixture is heated to undergo a polymerization reaction to obtain a prepolymer. The alkyl acrylate soft monomers account for ≥60wt% of the mass of the prepolymer, and the acrylate polar monomers account for <30wt% of the mass of the prepolymer.

[0022] The mixture of the prepolymer and the crosslinking agent is coated to form an adhesive coating, and then heated to undergo a crosslinking reaction to obtain an adhesive film.

[0023] In the above scheme, by adjusting the mass ratio of alkyl acrylate soft monomers to polar acrylate monomers, the wetting effect of the adhesive film can be improved, enhancing the interfacial adhesion of the adhesive film. Furthermore, the adhesive film exhibits excellent low-temperature low modulus and high creep recovery rate. Moreover, the use of a thermosetting process to form the adhesive film ensures good process stability, simplifies operation, and effectively reduces preparation costs.

[0024] In some embodiments, the weight-average molecular weight of the prepolymer is ≥600,000 Da.

[0025] In some embodiments, the prepolymer comprises an alkyl acrylate soft monomer as shown in formula (I).

[0026]

[0027] Wherein, R1 is independently selected from substituted or unsubstituted C1-C20 alkyl groups, and n1 is an integer greater than zero.

[0028] In some embodiments, the prepolymer comprises an acrylate polar monomer as shown in formula (II) and / or an acrylate polar monomer as shown in formula (III);

[0029]

[0030] Wherein, R2 is independently selected from substituted or unsubstituted C1-C10 alkyl groups, and R3 is selected from at least one of hydroxyl, carboxyl, epoxy, and amino groups; n2 and n3 are integers greater than zero.

[0031] In some embodiments, the prepolymer contains 60 wt% to 85 wt% alkyl acrylate soft monomers and 10 wt% to 25 wt% acrylate polar monomers.

[0032] Based on a prepolymer mass of 100 wt%, the prepolymer contains alkyl acrylate soft monomers with a mass percentage ≥ 60 wt%, specifically 60 wt%, 62 wt%, 65 wt%, 67 wt%, 69 wt%, 72 wt%, 75 wt%, etc.

[0033] 80wt% or 85wt%, etc., or other values ​​within the above range, are not limited here.

[0034] Based on a prepolymer mass of 100 wt%, the mass percentage of acrylate polar monomers in the prepolymer is <30 wt%, specifically it can be 5 wt%, 10 wt%, 15 wt%, 17 wt%, 19 wt%, 20 wt%, 25 wt%, 28 wt%, or 29 wt%, etc., and of course, other values ​​within the above range are also possible, and are not limited here. Excessive addition of acrylate polar monomers will cause an increase in the low-temperature modulus of the optical adhesive film, which is detrimental to bending under low-temperature conditions. Insufficient addition of acrylate polar monomers will lead to a decrease in the adhesive strength between the adhesive film and the interface to be bonded. Preferably, the mass percentage of acrylate polar monomers in the prepolymer is 10 wt% to 25 wt%.

[0035] In some embodiments, the prepolymer comprises two alkyl acrylate soft monomers, wherein one of the alkyl acrylate soft monomers is selected from butyl acrylate, and the butyl acrylate accounts for 5 wt% to 20 wt% of the mass of the prepolymer.

[0036] Specifically, the concentration can be 5wt%, 7wt%, 8wt%, 10wt%, 12wt%, 13wt%, 14wt%, 15wt%, 18wt%, or 20wt%, etc., or other values ​​within the above range. The addition of butyl acrylate can adjust the wettability of the adhesive film, improve its creep recovery rate, and enhance interfacial adhesion.

[0037] In some embodiments, the thermal initiator is selected from at least one of azobisisobutyronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate, azoisobutyl cyanoformamide, benzoyl peroxide, tert-butyl peroxide, tert-amyl peroxide, dicumyl peroxide, and hydrogen peroxide.

[0038] In some embodiments, the heating temperature of the polymerization reaction is 60°C to 80°C.

[0039] In some embodiments, the polymerization reaction takes 8 to 20 hours.

[0040] In some embodiments, the inert gas includes at least one of nitrogen, helium, neon, and krypton.

[0041] In some embodiments, the amount of the thermal initiator added is 0.02 wt% to 0.5 wt% of the total monomer mass.

[0042] In some embodiments, the crosslinking agent is selected from at least one of toluene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and epoxy crosslinking agents.

[0043] In some embodiments, the amount of crosslinking agent added is 0.02 wt% to 0.2 wt% of the total monomer mass.

[0044] Thirdly, this application provides a composite component, the composite component including a first component, a second component and an adhesive film located between the first component and the second component, the adhesive film including the adhesive film described in the first aspect or the adhesive film prepared according to the preparation method described in the second aspect.

[0045] In some embodiments, the shear storage modulus of the adhesive film is ≤35 kPa at a frequency of 1 Hz within a temperature range of 25°C; specifically, it can be 35 kPa, 32 kPa, 30 kPa, 28 kPa, 25 kPa, 22 kPa, or 20 kPa, etc., or other values ​​within the above range, which are not limited here. If the shear storage modulus of the adhesive film at room temperature is too high, it will lead to increased bending stress, causing the composite component to be easily damaged during bending.

[0046] In some embodiments, the shear storage modulus of the adhesive film is ≤200 kPa at a frequency of 1 Hz within a temperature range of -20°C; specifically, it can be 200 kPa, 190 kPa, 180 kPa, 170 kPa, 160 kPa, 150 kPa, 140 kPa, 130 kPa, or 100 kPa, etc., and of course, other values ​​within the above range are also possible, which are not limited here. If the shear storage modulus of the adhesive film is too high at low temperatures, it will cause the composite component to bend, break, or peel off at low temperatures.

[0047] In some embodiments, after being subjected to a shear stress of 20 kPa for 10 minutes and then recovering for 10 minutes, the creep recovery of the adhesive film is ≥90%. The creep recovery rate can specifically be 90%, 92%, 94%, 95%, 96%, 97%, 98%, etc., or other values ​​within the above range, which are not limited here. If the creep recovery rate of the adhesive film is too low, the composite components are prone to misalignment and damage during repeated folding. The adhesive film obtained in this application has a creep recovery rate of over 92%, and even after numerous folding tests, it can quickly recover, thus preventing damage between components connected by the adhesive film. Preferably, the creep recovery of the adhesive film is ≥92%.

[0048] In some embodiments, the glass transition temperature of the adhesive film is ≤-35℃. Specifically, it can be -35℃, -37℃, -38℃, -40℃, -42℃, -45℃, or -50℃, or other values ​​within the above range, which are not limited here. If the glass transition temperature of the adhesive film is too high, it will lead to a higher low-temperature modulus of the optical adhesive, causing the composite component to bend, break, or peel off at low temperatures.

[0049] In some embodiments, the adhesive force between the adhesive film and the first or second component is ≥1200 g / in; specifically, the adhesive force can be 1200 g / in, 1250 g / in, 1280 g / in, 1300 g / in, 1350 g / in, 1400 g / in, or 1500 g / in, etc., or other values ​​within the above range, which are not limited here. If the adhesive force is too low, the composite component is easily peeled off and damaged.

[0050] In some embodiments, the thickness of the adhesive film is 15μm to 200μm. Specifically, it can be 15μm, 20μm, 30μm, 45μm, 50μm, 60μm, 70μm, 80μm, or 100μm, etc., or other values ​​within the above range, which are not limited here.

[0051] Fourthly, this application provides an electronic device comprising the composite component described in the third aspect above.

[0052] Fifthly, this application provides a foldable mobile phone, the foldable mobile phone including the composite component described in the third aspect above.

[0053] Compared with the prior art, this application has at least the following beneficial effects:

[0054] The adhesive film provided in this application, by adjusting the mass ratio of alkyl acrylate soft monomers to polar acrylate monomers, can achieve better wetting effect and improve interfacial adhesion. Furthermore, the adhesive film exhibits excellent low-temperature low modulus and high creep recovery rate. This avoids the problem of foldable electronic devices using this adhesive film experiencing creep recovery during repeated folding, preventing the film from failing to move due to excessive adhesive force, thus extending the service life of the foldable electronic devices. Attached Figure Description

[0055] Figure 1 This is a schematic diagram of the structure of the composite component provided in the embodiments of this application;

[0056] Figure 2a , Figure 2b The figures show the rheological test curves and creep recovery rate curves of the adhesive film prepared in Example 2.

[0057] Figure 3a , Figure 3b The figures show the rheological test curves and creep recovery rate curves of the adhesive film prepared in Example 5, respectively.

[0058] Figure 4a , Figure 4b The figures show the rheological test curves and creep recovery rate curves of the adhesive film prepared in Example 8. Detailed Implementation

[0059] The following are preferred embodiments of the present application. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principles of the embodiments of the present application, and these improvements and modifications are also considered to be within the protection scope of the embodiments of the present application.

[0060] For simplicity, this paper only explicitly discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form an undefined range; and any lower limit can be combined with other lower limits to form an undefined range, just as any upper limit can be combined with any other upper limit to form an undefined range. Furthermore, although not explicitly stated, every point or individual value between the endpoints of a range is included within that range. Therefore, each point or individual value can serve as its own lower or upper limit and be combined with any other point or individual value, or with other lower or upper limits, to form an undefined range.

[0061] In this description, it should be noted that, unless otherwise stated, "above" and "below" include the stated number, and "multiple" in "one or more" means two or more.

[0062] The foregoing description of this application is not intended to describe every disclosed implementation or method. Instead, the following description provides more specific examples of exemplary embodiments. Throughout the application, guidance is provided through a series of embodiments that can be used in various combinations. The examples listed are representative only and should not be construed as exhaustive.

[0063] Currently, foldable displays require multiple layers of optical films, such as polarizers and transparent polyimide cover films, to be laminated on the top, serving multiple functions including preventing ambient light reflection and protecting the screen. A support film and a metal support layer are needed on the bottom of the screen to provide support and prevent excessive deformation under pressure, which could lead to display defects. Various films of different materials are bonded together using optically clear adhesive (OCA).

[0064] Optical transparent adhesive (OCA) is a viscoelastic material that possesses both adhesive strength and viscoelastic properties at room temperature. Common OCA used in 2D or 3D display modules exhibits high adhesive strength, firmly bonding the upper and lower interfaces to be bonded. In the bonding process of foldable display modules, the upper and lower interfaces require high-adhesion OCA to bond the film materials together.

[0065] However, during bending, the upper and lower film materials will misalign with each other, and the amount of misalignment gradually increases with the bending radius and the distance from the neutral layer. In currently used foldable display modules, the amount of misalignment between the upper and lower film layers can reach three times or more the thickness of the optically transparent adhesive (OCA), requiring the OCA to have a high creep recovery rate.

[0066] Currently, the optically transparent adhesives used for bonding ordinary 2D or 3D display modules have high adhesive strength but poor creep recovery rate, which cannot meet the requirements of foldable display modules. Furthermore, during the bending process of foldable display modules, the high cohesive force of ordinary OCA adhesives causes the upper and lower film layers to be firmly bonded together, preventing them from shifting and easily leading to damage to the foldable display module.

[0067] Therefore, this application develops an adhesive film suitable for foldable display modules. The adhesive film is prepared by crosslinking a prepolymer, which includes alkyl acrylate soft monomers and acrylate polar monomers. The mass percentage of the alkyl acrylate soft monomers in the prepolymer is ≥60wt%, and the mass percentage of the acrylate polar monomers in the prepolymer is <30wt%.

[0068] In the above solution, by adjusting the mass ratio of alkyl acrylate soft monomers to polar acrylate monomers, the wetting effect of the adhesive film can be improved, enhancing the interfacial adhesion of the adhesive film. Furthermore, the adhesive film exhibits excellent low-temperature low modulus and high creep recovery rate. This avoids the need for foldable electronic devices using this adhesive film to creep and recover with the misalignment between film materials during repeated folding, preventing the film materials from failing to move due to excessive adhesive force, thus extending the service life of foldable electronic devices.

[0069] In one feasible embodiment, the prepolymer comprises an alkyl acrylate soft monomer as shown in formula (I).

[0070]

[0071] Wherein, R1 is independently selected from substituted or unsubstituted C1-C20 alkyl groups, and n1 is an integer greater than zero.

[0072] Optionally, the C1-C20 alkyl groups can be chain alkyl groups, which can be straight-chain alkyl groups, branched alkyl groups, or cyclic alkyl groups. Preferably, the C1-C20 alkyl groups can be chain alkyl groups, and more preferably, the C1-C20 alkyl groups can be straight-chain alkyl groups. The preferred lower limit for the number of carbon atoms in the C1-C20 alkyl groups is 1, 2, 3, 4, 6, or 8, and the preferred upper limit is 10, 12, 14, 15, 18, or 20. Examples of C1-C20 alkyl groups include: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, neopentyl, hexyl, 2-methylpentyl, 3-methylpentyl, 1,1,2-trimethyl-propyl, 3,3-dimethyl-butyl, heptyl, 2-heptyl, 3-heptyl, 2-methylhexyl, 3-methylhexyl, isoheptyl, octyl, nonyl, and decyl.

[0073] In some specific embodiments, the alkyl acrylate soft monomer can be at least one of 2-ethylhexyl (meth)acrylate (abbreviated as 2-EHA), methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate (abbreviated as BA), isobutyl (meth)acrylate, n-pentyl (meth)acrylate, hexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate (abbreviated as 2-EHMA), n-nonyl (meth)acrylate, isononyl (meth)acrylate, n-decyl (meth)acrylate, isodecyl (meth)acrylate, dodecyl (meth)acrylate, isooctyl (meth)acrylate, hexadecyl (meth)acrylate, and octadecyl (meth)acrylate. Of course, it can also be other monomers having the structure shown in formula (I), which is not limited here.

[0074] Based on a prepolymer mass of 100 wt%, the alkyl acrylate soft monomer in the prepolymer has a mass percentage of ≥60 wt%, specifically 60 wt%, 62 wt%, 65 wt%, 67 wt%, 69 wt%, 72 wt%, 75 wt%, 80 wt%, 85 wt%, or 90 wt%, etc., and other values ​​within the above range are also possible, without limitation. Preferably, the alkyl acrylate soft monomer in the prepolymer has a mass percentage of 60 wt% to 85 wt%.

[0075] In some specific embodiments, the alkyl acrylate soft monomer includes at least butyl acrylate (BA), and the butyl acrylate in the prepolymer has a mass percentage of 5 wt% to 30 wt%, specifically 5 wt%, 15 wt%, 19.5 wt%, 20 wt%, 23 wt%, 29.5 wt%, or 30 wt%, etc., or other values ​​within the above range, which are not limited here. Excessive alkyl acrylate soft monomer increases the flexibility of the adhesive film but decreases the low-temperature modulus. Preferably, the butyl acrylate in the prepolymer has a mass percentage of 5 wt% to 20 wt%.

[0076] In one feasible embodiment, the prepolymer comprises an acrylate polar monomer as shown in Formula (II) and / or an acrylate polar monomer as shown in Formula (III).

[0077]

[0078] Wherein, R2 is independently selected from substituted or unsubstituted C1-C10 alkyl groups, and R3 is selected from at least one of hydroxyl, carboxyl, epoxy, amino, and sulfonic acid groups; n2 and n3 are integers greater than zero.

[0079] Optionally, the C1-C10 alkyl groups can be chain alkyl groups, which can be straight-chain alkyl groups, branched alkyl groups, or cyclic alkyl groups. Preferably, the C1-C10 alkyl groups can be chain alkyl groups, and more preferably, the C1-C10 alkyl groups can be straight-chain alkyl groups. The preferred lower limit for the number of carbon atoms in the C1-C10 alkyl groups is 1, 2, 3, or 4, and the preferred upper limit is 5, 6, 8, or 10. Examples of C1-C10 alkyl groups include: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, neopentyl, hexyl, 2-methyl-pentyl, 3-methyl-pentyl, 1,1,2-trimethyl-propyl, 3,3-dimethyl-butyl, heptyl, 2-heptyl, 3-heptyl, 2-methylhexyl, 3-methylhexyl, isoheptyl, octyl, nonyl, and decyl.

[0080] In some specific embodiments, the polar monomer of the acrylate can be any one of acrylic acid (abbreviated as AA), hydroxybutyl acrylate (abbreviated as 4HBA), hydroxyethyl acrylate (abbreviated as 2HEA), 2-hydroxypropyl acrylate (abbreviated as HPA), hydroxyethyl methacrylate (abbreviated as HEMA), and hydroxypropyl methacrylate (abbreviated as HPMA). Of course, it can also be other monomers having the structure shown in formula (II), which are not limited here.

[0081] Based on a prepolymer mass of 100 wt%, the mass percentage of acrylate polar monomers in the prepolymer is <30 wt%, specifically it can be 5 wt%, 10 wt%, 15 wt%, 17 wt%, 19 wt%, 20 wt%, 25 wt%, 28 wt%, or 29 wt%, etc., and other values ​​within the above range are also possible, without limitation. Excessive acrylate polar monomer content will cause an increase in the low-temperature modulus of the optical adhesive film, which is detrimental to bending under low-temperature conditions. Insufficient acrylate polar monomer content leads to a decrease in the adhesive strength between the adhesive film and the interface to be bonded. Preferably, the mass percentage of acrylate polar monomers in the prepolymer is 10 wt% to 25 wt%.

[0082] In some specific embodiments, the weight-average molecular weight of the prepolymer is ≥600,000 Da, specifically 600,000 Da, 800,000 Da, 1,000,000 Da, 1,050,000 Da, 110,000 Da, 1,150,000 Da, 1,180,000 Da, 1,200,000 Da, 1,300,000 Da, or 1,400,000 Da, etc., or other values ​​within the above range, which are not limited here. Preferably, the weight-average molecular weight of the prepolymer is ≥1,000,000 Da.

[0083] Secondly, this application also provides a method for preparing an adhesive film, the method comprising the following steps:

[0084] S10, under the protection of an inert gas, alkyl acrylate soft monomers, acrylate polar monomers and solvents are mixed and a thermal initiator is added, and the mixture is heated to undergo a polymerization reaction to obtain a prepolymer, wherein the mass percentage of the alkyl acrylate soft monomers in the prepolymer is ≥60wt%, and the mass percentage of the acrylate polar monomers in the prepolymer is <30wt%.

[0085] S20, the mixture of the prepolymer and the crosslinking agent is coated to form an adhesive coating, and a crosslinking reaction is carried out by heating to obtain an adhesive film.

[0086] In the above scheme, by adjusting the mass ratio of alkyl acrylate soft monomers to polar acrylate monomers, the wetting effect of the adhesive film can be improved, enhancing the interfacial adhesion of the adhesive film. Furthermore, the adhesive film exhibits excellent low-temperature low modulus and high creep recovery rate. Moreover, the use of a thermosetting process to form the adhesive film ensures good process stability, simplifies operation, and effectively reduces preparation costs.

[0087] It should be noted that thermosetting is easier to control than photocuring, and can improve the creep recovery rate and adhesion of the adhesive film. In contrast, photocuring requires strict control of the uniformity of ultraviolet light, as well as the humidity and airflow inside the ultraviolet lamp box, making precise control extremely difficult.

[0088] The following is a detailed introduction to this solution:

[0089] S10 involves mixing alkyl acrylate soft monomers, polar acrylate monomers, and solvents under an inert gas atmosphere, adding a thermal initiator, and heating to induce a polymerization reaction to obtain a prepolymer.

[0090] In some embodiments, at least one alkyl acrylate soft monomer and at least one polar acrylate monomer may be mixed with a solvent, which may be any one of ethyl acetate, toluene, or butanone.

[0091] The amount of solvent added is 1-2 times the total mass of all monomers. The solvent thoroughly mixes and dissolves the monomers, which helps to improve the uniformity of the polymerization reaction.

[0092] A thermal initiator is added to the mixture after mixing. The thermal initiator is selected from at least one of azobisisobutyronitrile (AIBN), azobisisoheptanenitrile (AIBN), dimethyl azobisisobutyrate (DIH), azoisobutyl cyanoformamide (AIBN), benzoyl peroxide, tert-butyl peroxide, tert-amyl peroxide, dicumyl peroxide, and hydrogen peroxide. During heating, the monomers polymerize to obtain a prepolymer. The addition of the thermal initiator promotes a more complete polymerization reaction of the monomers and improves the reaction efficiency. Preferably, the thermal initiator is selected from azobisisobutyronitrile (AIBN) with the chemical formula C8H. 12 N4 is soluble in organic solvents such as methanol, ethanol, diethyl ether, butanone, toluene, petroleum ether, and aniline. It decomposes upon heating, releasing nitrogen gas and organic cyanides containing the -(CH2)2-C-CN group.

[0093] As an optional technical solution in this application, the amount of thermal initiator added is 0.02wt% to 0.5wt% of the total monomer mass, specifically 0.02wt%, 0.025wt%, 0.03wt%, 0.05wt%, 0.06wt%, 0.1wt%, 0.15wt%, 0.2wt%, 0.3wt%, or 0.5wt%, etc., or other values ​​within the above range, which are not limited here. Adding too much thermal initiator will lead to explosive polymerization, while adding too little will slow down the reaction and reduce the conversion rate. Preferably, the amount of thermal initiator added is 0.02wt% to 0.06wt% of the total monomer mass.

[0094] The alkyl acrylate soft monomer is a monomer having the structure shown in formula (I) above. The polar acrylate monomer can be a monomer having the structure shown in formula (II) and / or formula (III) above, which will not be elaborated here.

[0095] Based on a prepolymer mass of 100 wt%, the alkyl acrylate soft monomer in the prepolymer has a mass percentage of ≥60 wt%, specifically 60 wt%, 62 wt%, 65 wt%, 67 wt%, 69 wt%, 72 wt%, 75 wt%, 80 wt%, 85 wt%, or 90 wt%, etc., and other values ​​within the above range are also possible, without limitation. Preferably, the alkyl acrylate soft monomer in the prepolymer has a mass percentage of 60 wt% to 85 wt%.

[0096] In some specific embodiments, the alkyl acrylate soft monomer includes at least butyl acrylate (BA), and the butyl acrylate in the prepolymer has a mass percentage of 5 wt% to 30 wt%, specifically 5 wt%, 15 wt%, 19.5 wt%, 20 wt%, 23 wt%, 29.5 wt%, or 30 wt%, etc., or other values ​​within the above range, which are not limited here. Excessive alkyl acrylate soft monomer increases the flexibility of the adhesive film but decreases the low-temperature modulus. Preferably, the butyl acrylate in the prepolymer has a mass percentage of 5 wt% to 20 wt%.

[0097] Butyl acrylate has a melting point of -69℃ and exhibits good interfacial wetting properties. It can polymerize to form lower modulus polymers, helping to improve the adhesion of adhesive films to various interfaces. Furthermore, butyl acrylate has low molecular steric hindrance, which can increase the creep recovery rate of adhesive films, resulting in high creep recovery rates.

[0098] Based on a prepolymer mass of 100 wt%, the mass percentage of acrylate polar monomers in the prepolymer is <30 wt%, specifically it can be 5 wt%, 10 wt%, 15 wt%, 17 wt%, 19 wt%, 20 wt%, 25 wt%, 28 wt%, or 29 wt%, etc., and other values ​​within the above range are also possible, without limitation. Excessive addition of acrylate polar monomers will cause an increase in the low-temperature modulus of the optical adhesive film, which is detrimental to bending under low-temperature conditions. Insufficient addition of acrylate polar monomers will lead to a decrease in the adhesive strength between the adhesive film and the interface to be bonded. Preferably, the mass percentage of acrylate polar monomers in the prepolymer is 10 wt% to 25 wt%.

[0099] As an optional technical solution in this application, the heating temperature of the polymerization reaction is 60℃~80℃, specifically 60℃, 62℃, 64℃, 65℃, 66℃, 67℃, 69℃, 70℃, 75℃, or 80℃, etc., and of course, other values ​​within the above range are also possible, without limitation. Excessively high polymerization temperature will lead to an overly rapid polymerization reaction, resulting in a sharp increase in polymer viscosity, making the reaction difficult to control and hindering the preparation of an ideal adhesive film. Conversely, excessively low polymerization temperature will slow down the polymerization reaction, reduce the conversion rate, and prolong the polymerization time, which is detrimental to reducing production costs. Preferably, the heating temperature of the polymerization reaction is 65℃~70℃.

[0100] As an optional technical solution in this application, the polymerization reaction time is 8h to 20h, specifically 8h, 8.5h, 9h, 9.5h, 10h, 11h, 12h, 15h, 18h, or 20h, etc., or other values ​​within the above range, which are not limited here. If the polymerization reaction time is too long, the prepolymer molecular weight is too large, and the viscosity of the prepolymer is too high, which is not conducive to the subsequent coating process; if the polymerization reaction time is too short, the prepolymer molecular weight is too small, the solution viscosity is too low, the coating difficulty increases, and the properties of the finished adhesive do not meet the requirements.

[0101] As an optional technical solution in this application, the inert gas includes at least one of nitrogen, helium, neon, and krypton.

[0102] In the actual preparation process, alkyl acrylate soft monomers, polar acrylate monomers, and solvents are mixed, and then nitrogen or other inert gases are introduced to expel as much oxygen as possible from the mixed solution, thus avoiding oxygen-induced polymerization inhibition. Oxygen-induced polymerization inhibition may cause a large number of oxidizing structures such as hydroxyl, carbonyl, and peroxy groups to appear on the surface of the adhesive film coating, thereby affecting the stability of the adhesive film coating and potentially even the bonding performance of the cured adhesive film.

[0103] In one specific embodiment, the alkyl acrylate soft monomer is 2-ethylhexyl acrylate and butyl acrylate, and the acrylate polar monomer is hydroxybutyl acrylate.

[0104] S20, the mixture of the prepolymer and the crosslinking agent is coated to form an adhesive coating, and a crosslinking reaction is carried out by heating to obtain an adhesive film.

[0105] The molecular weight of the prepolymer reaches over 600,000 Da, and the prepolymer is cross-linked to form a polymer through a cross-linking agent.

[0106] As an optional technical solution in this application, the crosslinking agent includes at least one of isocyanate (TDI), hexamethylene isocyanate (HDI), and isophorone diisocyanate (IPDI). The highly unsaturated structure of the crosslinking agent determines its high reactivity. According to the electronic resonance theory of the isocyanate group, the resonance effect of -NCO results in an uneven charge distribution, generating nucleophilic and electrophilic centers. The electronegativity order of nitrogen, carbon, and oxygen atoms in the isocyanate group is O > N > C. Therefore, nitrogen and oxygen atoms have high electron cloud densities, exhibiting strong electronegativity and readily reacting with electrophilic reagents. Conversely, due to the effect of the strongly electronegative atoms at both ends, the electron cloud density of carbon atoms decreases, exhibiting strong positive electronegativity and becoming electrophilic centers. Therefore, the isocyanate group readily reacts with compounds containing hydrogen atoms.

[0107] In the actual preparation process, the crosslinking reaction can be accelerated by coating film formation. After coating, the adhesive film needs to be placed in a temperature chamber of 30℃-60℃ for curing to accelerate the crosslinking reaction between the crosslinking agent and the prepolymer. The curing and crosslinking reaction time is 24-120 hours, specifically 24 hours, 48 ​​hours, 72 hours, 96 hours, or 120 hours, etc., or other values ​​within the above range, which are not limited here.

[0108] As an optional technical solution in this application, the amount of crosslinking agent added is 0.02wt% to 0.2wt% of the total monomer mass, specifically 0.02wt%, 0.025wt%, 0.03wt%, 0.035wt%, 0.04wt%, 0.05wt%, 0.08wt%, 0.1wt%, 0.15wt%, or 0.2wt%, etc., and of course, other values ​​within the above range are also possible, and are not limited here. Preferably, the amount of crosslinking agent added is 0.02wt% to 0.06wt% of the total monomer mass.

[0109] By controlling the various parameters of the cross-linking reaction, it is beneficial to form a uniform and stable cross-linking product, which in turn improves the adhesive strength of the adhesive film.

[0110] In one specific embodiment, the alkyl acrylate soft monomer is 2-ethylhexyl acrylate and butyl acrylate, and the acrylate polar monomer is hydroxybutyl acrylate.

[0111] Thirdly, this application also provides a composite component 100, such as Figure 1 As shown, the composite component 100 includes a first component 10, a second component 20, and an adhesive film 30 located between the first component 10 and the second component 20. The adhesive film 30 includes the adhesive film described in the first aspect above or an adhesive film prepared according to the preparation method described in the second aspect above.

[0112] As an optional technical solution in this application, the shear storage modulus of the adhesive film is ≤35KPa at a frequency of 1Hz within a temperature range of 25℃; specifically, it can be 35KPa, 32KPa, 30KPa, 28KPa, 25KPa, 22KPa, or 20KPa, etc., or other values ​​within the above range, which are not limited here. If the shear storage modulus of the adhesive film at room temperature is too high, it will lead to increased bending stress, causing the composite component to be easily damaged during bending.

[0113] As an optional technical solution in this application, within a temperature range of -20℃ and a frequency of 1Hz, the shear storage modulus of the adhesive film is ≤200KPa; specifically, it can be 200KPa, 190KPa, 180KPa, 170KPa, 160KPa, 150KPa, 140KPa, 130KPa, or 100KPa, etc., or other values ​​within the above range, which are not limited here. If the shear storage modulus of the adhesive film is too high at low temperatures, it will cause the composite component to bend, break, or peel off at low temperatures.

[0114] As an optional technical solution in this application, the glass transition temperature of the adhesive film is ≤-35℃, specifically -35℃, -37℃, -38℃, -40℃, -42℃, -45℃, or -50℃, etc., or other values ​​within the above range, which are not limited here. If the glass transition temperature of the adhesive film is too high, it will lead to a higher low-temperature modulus of the optical adhesive, resulting in low-temperature bending breakage or peeling of the composite component.

[0115] As an optional technical solution in this application, after being subjected to a shear stress of 20 kPa for 10 minutes and then recovering for 10 minutes, the creep recovery rate of the adhesive film is ≥90%. The creep recovery rate can specifically be 90%, 92%, 94%, 95%, 96%, 97%, 98%, etc., or other values ​​within the above range, which are not limited here. If the creep recovery rate of the adhesive film is too low, the composite components are prone to misalignment and damage during repeated folding. The creep recovery rate of the adhesive film obtained in this application can reach over 92%, and even after numerous folding tests, the adhesive film can quickly recover, thus preventing damage between components connected by the adhesive film.

[0116] The adhesive film has an adhesion force ≥1200 g / inch between itself and the first or second component; specifically, the adhesion force can be 1200 g / inch, 1250 g / inch, 1280 g / inch, 1300 g / inch, 1350 g / inch, 1400 g / inch, or 1500 g / inch, etc., or other values ​​within the above range, which are not limited here.

[0117] As an optional technical solution of this application, the thickness of the adhesive film is 15μm to 100μm, specifically it can be 15μm, 20μm, 30μm, 45μm, 50μm, 60μm, 70μm, 80μm or 100μm, etc., and of course it can also be other values ​​within the above range, which are not limited here.

[0118] In specific embodiments, the adhesive film can be used for bonding interfaces of polyimide (CPI) film, polyethylene terephthalate (PET) film, polymethyl methacrylate (PMMA) film, cellulose triacetate film (TAC), rigid film, polycarbonate (PC) film, ultra-thin glass, stainless steel parts, titanium alloy parts, aluminum alloy parts, carbon fiber parts, bamboo fiber parts, sheet metal parts, etc.

[0119] Fourthly, this application provides an electronic device comprising the aforementioned composite components.

[0120] Electronic devices can also include other functions such as personal digital assistant and / or music player functions, such as mobile phones, tablets, wearable devices with wireless communication capabilities (such as smartwatches), etc.

[0121] In some embodiments, the electronic device includes a curved display or a foldable display. A curved display is a display made of flexible plastic; compared to a flat display, a curved display is more flexible and less prone to breakage. Curved displays use non-rigid glass as a substrate, which is more flexible and less likely to break. This reduces the likelihood of screen wear and tear, especially for frequently touched mobile phone screens. A foldable display is a display that can be bent.

[0122] Since foldable displays need to be folded repeatedly, the adhesive film needs to achieve a balance in terms of adhesive strength, creep recovery rate, and low temperature modulus to improve the service life of foldable displays.

[0123] Specifically, the electronic device includes composite components, which can be foldable display components, hinge components, mid-frame components, etc. The adhesive film provided in this application has excellent low-temperature low modulus and high creep recovery rate, making it suitable for foldable applications.

[0124] The preparation of adhesive film is described below using an adhesive film as an example and in conjunction with specific embodiments. Those skilled in the art will understand that the preparation methods described below are merely examples and do not limit this solution.

[0125] I. Preparation of Adhesive Film

[0126] Under nitrogen protection, alkyl acrylate soft monomers, polar acrylate monomers and ethyl acetate are mixed and a thermal initiator (azobisisobutyronitrile, AIBN) is added. The mixture is heated to 60-80℃ for 8-20 hours to obtain a prepolymer.

[0127] The mixture of the prepolymer and crosslinking agent is coated onto a heavy release film using a high-precision coating device to form an adhesive coating. The thickness of the adhesive film is controlled to be between 25 μm and 50 μm. Then, a lightweight film is covered on top, and the film is wound up to obtain an adhesive film roll.

[0128] The adhesive films of Examples 1 to 19 (i.e., S1 to S19 in the table) and the adhesive of Comparative Example 1 (i.e., R1 in the table) prepared according to the above method are shown in Table 1.

[0129] Table 1

[0130]

[0131]

[0132] In the table, " / " indicates that it has not been added.

[0133] II. Performance Testing:

[0134] Test sample preparation:

[0135] 1. Cut the adhesive film into small pieces, peel off the light release film, and bond the two pieces of adhesive film with the light release film removed by pressing with a 2KG roller. Then remove the heavy release film on one side and repeat the above operation to finally laminate the adhesive film to about 0.5mm to 1mm.

[0136] 2. Use a laminating device to press the adhesive film stack together. Set the device temperature to 80℃ and the pressing thickness to 0.5mm~1mm. After pressing for 20 minutes, remove the sample and then use the device to cut the prepared adhesive film stack into round pieces with a diameter of 8mm for later use.

[0137] 1) Rheological property testing of adhesive film

[0138] Test equipment: Rotational rheometer.

[0139] Sample quantity: 5 adhesive film samples with a diameter of 8mm.

[0140] Test steps:

[0141] Remove the release film from the prepared sample and attach it to the test area of ​​the rheometer.

[0142] Follow the normal rheometer testing procedure and set the parameters as follows: Temperature: -40-100℃, heating rate 1℃ / min, strain: 1%, frequency: 1H. Z Z-axis pressure 0.1N.

[0143] Save the original spectrum and record the storage modulus G' and the glass transition temperature (Tg) corresponding to the peak value of tanδ at -40℃, -20℃, 25℃, and 60℃.

[0144] 2) Creep recovery rate test of adhesive film

[0145] Test equipment: Rotational rheometer.

[0146] Sample quantity: 5 samples of laminated adhesive with a diameter of 8mm.

[0147] Test steps:

[0148] Remove the release film from the prepared sample and attach it to the test area of ​​the rheometer.

[0149] Follow the normal rheometer testing procedure and set the parameters as follows: Apply a force of 20 kPa for 600 s. Remove the external force and test the recovery curve of the adhesive film for 600 s. Apply a Z-axis pressure of 0.1 N and record the deformation and recovery curve of the adhesive film during the test.

[0150] Save the original graph, record the maximum deformation and the final recovery value, and calculate the creep recovery rate.

[0151] The prepared Examples 1 to 19 (i.e., S1 to S19 in the table) and Comparative Example 1 (i.e., R1 in the table) were subjected to the above performance tests, and the test results are shown in Table 2.

[0152] Table 2

[0153]

[0154]

[0155] According to the test data of Examples 1 to 18 in Tables 1 and 2 above, when the mass ratio of alkyl acrylate soft monomers to polar acrylate monomers in the adhesive film is controlled within a suitable range, the wetting effect of the adhesive film is improved, the interfacial adhesion of the adhesive film is enhanced, and the adhesive film exhibits excellent low-temperature low modulus and high creep recovery rate. This avoids the need for foldable electronic devices using this adhesive film to creep and recover with the misalignment between film materials during repeated folding, preventing the film materials from failing to move due to excessive adhesive force, thus improving the service life of foldable electronic devices.

[0156] Figure 2a The rheological test curve of the adhesive film prepared in Example 2 is shown. Figure 2b The creep recovery rate curve of the adhesive film prepared in Example 2 is shown; Figure 2a and Figure 2b It can be seen that, compared with Example 3, the prepolymer of the adhesive film in Example 2 has added the polar monomer acrylic acid (AA), which can increase the polarity of the prepolymer of the adhesive film, that is, it can increase the interfacial adhesion of the adhesive film. Thus, the addition of the polar monomer acrylic acid can improve the adhesion of the adhesive film and also improve the creep recovery rate of the adhesive film.

[0157] Figure 3a The rheological test curve of the adhesive film prepared in Example 5 is shown. Figure 3b The creep recovery rate curve is shown for the adhesive film prepared in Example 5; please refer to... Figures 3a to 3b In Example 5, the prepolymer included 70g of 2-ethylhexyl acrylate, 10g of butyl acrylate, and 20g of hydroxybutyl acrylate. Compared with Comparative Example 1 without the addition of butyl acrylate (BA), the creep recovery rate of Example 5 was higher than that of Comparative Example 1. This shows that the addition of butyl acrylate can adjust the wettability of the adhesive film, improve the creep recovery rate of the adhesive film, and improve the interfacial adhesion.

[0158] Figure 4a The rheological test curve of the adhesive film prepared in Example 7 is shown. Figure 4bThe image shows the creep recovery rate curve of the adhesive film prepared in Example 7. The prepolymer of the adhesive film in Example 7 includes 80g of 2-ethylhexyl acrylate and 20g of hydroxybutyl acrylate, which enables the adhesive film to have excellent creep recovery rate and adhesive strength.

[0159] According to the test data of Examples 1-2 and Examples 3-5, when the crosslinking agent used is TDI crosslinking agent, the adhesive film can exhibit a better creep recovery rate.

[0160] According to the test data from Examples 5 and 15-16, the creep recovery performance of various adhesive films prepared by combining 2-ethylhexyl acrylate with different alkyl acrylate soft monomers varies slightly. This is because other monomers have large steric hindrance, resulting in poor creep recovery of the finished adhesive film. Preferably, the combination of 2-ethylhexyl acrylate and butyl acrylate yields the adhesive film with the best creep recovery performance.

[0161] According to the test data of Examples 5 and 17 to 18, different alkyl acrylate soft monomers can cooperate with acrylate polar monomers to adjust the wettability of the adhesive film.

[0162] According to the test data from Examples 5 and 19, the amount of polar monomer added in Example 19 was too small, only 4g. Its room temperature storage modulus and high temperature storage modulus were both poor, resulting in low adhesion and breakage after 200,000 dynamic bends. Preferably, the mass percentage of the acrylate polar monomer in the prepolymer is 10wt% to 25wt%.

[0163] Although this application discloses preferred embodiments as described above, it is not intended to limit the claims. Any person skilled in the art can make several possible changes and modifications without departing from the concept of this application. Therefore, the scope of protection of this application should be determined by the scope defined in the claims of this application.

Claims

1. An adhesive film, characterized in that, The adhesive film is suitable for foldable electronic devices. The adhesive film is prepared by a crosslinking reaction of a mixture of a prepolymer and a crosslinking agent. The prepolymer includes alkyl acrylate soft monomers and polar acrylate monomers; wherein the alkyl acrylate soft monomers account for 75wt%~85wt% of the mass of the prepolymer, and the alkyl acrylate soft monomers include butyl acrylate, which accounts for 10wt%~23wt% of the mass of the prepolymer; the polar acrylate monomers account for 15wt%~25wt% of the mass of the prepolymer; the weight-average molecular weight of the prepolymer is ≥1,000,000 Da. The crosslinking agent is selected from at least one of toluene diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate.

2. The adhesive film according to claim 1, characterized in that, The prepolymer comprises alkyl acrylate soft monomers as shown in formula (I), （I）； Wherein, R1 is independently selected from substituted or unsubstituted C1-C20 alkyl groups, and n1 is an integer greater than zero.

3. The adhesive film according to claim 1, characterized in that, The prepolymer comprises an acrylate polar monomer as shown in Formula (II) and / or an acrylate polar monomer as shown in Formula (III); (II)) (III)) Wherein, R2 is independently selected from substituted or unsubstituted C1-C10 alkyl groups, and R3 is selected from at least one of hydroxyl, carboxyl, epoxy, and amino groups; n2 and n3 are integers greater than zero.

4. A method for preparing an adhesive film, wherein the adhesive film is suitable for foldable electronic devices, characterized in that, The method includes: Under inert gas protection, alkyl acrylate soft monomers, polar acrylate monomers, and solvents are mixed, and a thermal initiator is added. The mixture is then heated to induce a polymerization reaction, yielding a prepolymer. The alkyl acrylate soft monomers comprise 75 wt% to 85 wt% of the prepolymer by mass, and include butyl acrylate, which comprises 10 wt% to 23 wt% of the prepolymer by mass. The polar acrylate monomers comprise 15 wt% to 25 wt% of the prepolymer by mass. The weight-average molecular weight of the prepolymer is ≥1,000,000 Da. The mixture of the prepolymer and the crosslinking agent is coated to form an adhesive coating, and then heated to undergo a crosslinking reaction to obtain an adhesive film; the crosslinking agent is selected from at least one of toluene diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate.

5. The preparation method according to claim 4, characterized in that, The prepolymer comprises alkyl acrylate soft monomers as shown in formula (I), （I）； Wherein, R1 is independently selected from substituted or unsubstituted C1-C20 alkyl groups, and n1 is an integer greater than zero.

6. The preparation method according to claim 4, characterized in that, The prepolymer comprises an acrylate polar monomer as shown in Formula (II) and / or an acrylate polar monomer as shown in Formula (III); (II)) (III)) Wherein, R2 is independently selected from substituted or unsubstituted C1-C10 alkyl groups, and R3 is selected from at least one of hydroxyl, carboxyl, epoxy, and amino groups; n2 and n3 are integers greater than zero.

7. The preparation method according to claim 4, characterized in that, It satisfies at least one of the following characteristics: The thermal initiator is selected from at least one of azobisisobutyronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate, azoisobutylcyanoformamide, benzoyl peroxide, tert-butyl peroxide, tert-amyl peroxide, dicumyl peroxide, and hydrogen peroxide. The heating temperature for the polymerization reaction is 60℃~80℃; The polymerization reaction takes 8 to 20 hours. The inert gas includes at least one of nitrogen, helium, neon, and krypton; The amount of the thermal initiator added is 0.02wt%~0.5wt% of the total mass of the monomers; The amount of crosslinking agent added is 0.02wt% to 0.2wt% of the total monomer mass.

8. A composite component comprising a first component, a second component, and an adhesive film located between the first component and the second component, wherein the adhesive film comprises the adhesive film according to any one of claims 1 to 3 or the adhesive film prepared by the preparation method according to any one of claims 4 to 7.

9. The composite component according to claim 8, characterized in that, It satisfies at least one of the following characteristics: Within a temperature range of 25°C and a frequency of 1Hz, the shear storage modulus of the adhesive film is ≤35KPa; Within a temperature range of -20℃ and at a frequency of 1Hz, the shear storage modulus of the adhesive film is ≤200KPa; After being subjected to a shear stress of 20 kPa for 10 minutes and then recovering for 10 minutes, the creep recovery of the adhesive film is ≥90%. The glass transition temperature of the adhesive film is ≤-35℃; The adhesive film has an adhesion force ≥1200 g / inch to the first component or the second component; The thickness of the adhesive film is 15μm~200μm.

10. An electronic device, characterized in that, The electronic device includes the composite component as described in claim 8 or 9.

11. A foldable mobile phone, characterized in that, The foldable phone includes the composite component as described in claim 8 or 9.

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