CN116052530A

CN116052530A - Composite film and preparation method thereof, cover plate assembly, display screen and electronic device

Info

Publication number: CN116052530A
Application number: CN202210557666.1A
Authority: CN
Inventors: 朱昆鹏; 王鹏; 王枝泽; 杨汉宁
Original assignee: Honor Device Co Ltd
Current assignee: Honor Device Co Ltd
Priority date: 2022-05-19
Filing date: 2022-05-19
Publication date: 2023-05-02
Anticipated expiration: 2042-05-19
Also published as: CN116052530B

Abstract

The embodiment of the application relates to the technical field of display, in particular to a composite film, a preparation method thereof, a cover plate assembly, a display screen and an electronic device. The composite film comprises a first substrate layer, a buffer layer and a second substrate layer which are sequentially laminated, wherein the buffer layer is in direct contact with the surfaces of the first substrate layer and the second substrate layer. The composite film can be used as a cover plate of an electronic device or used as a protective film attached to the cover plate in the electronic device or used as a supporting component in a foldable electronic device. In the composite film, the buffer layer has certain energy absorption and shock absorption effects, and can improve the extrusion resistance and shock resistance of the electronic device. In addition, in the composite film, the buffer layer is in direct contact with the surfaces of the first substrate layer and the second substrate layer, so that the laminating adhesive between the substrate and the buffer layer is reduced, the thickness of the composite film is reduced, and the risk of separation between adjacent layers in the bending process of the composite film is reduced.

Description

Composite film and preparation method thereof, cover plate assembly, display screen and electronic device

Technical Field

The application relates to the technical field of display, in particular to a composite film, a preparation method thereof, a cover plate assembly, a display screen and an electronic device.

Background

At present, electronic devices (such as mobile phones), particularly foldable electronic devices, are increasingly thinner, and accordingly, the reliability requirements of the electronic devices are also increasingly higher. The crush and impact resistance of electronic devices needs to be improved.

Disclosure of Invention

The first aspect of the present application provides a method for preparing a composite film, comprising:

coating a raw material solution on the first substrate layer, wherein the raw material solution is one of a raw material solution of polyurethane elastomer, a raw material solution of polyamide elastomer and a raw material solution of polysiloxane elastomer;

baking to pre-cure the raw material solution into a first intermediate layer;

bonding, namely bonding the second substrate layer to one side of the first intermediate layer far away from the first substrate layer; and

curing, and curing the first intermediate layer, wherein the cured first intermediate layer is in direct contact with the first substrate layer.

In the preparation method, the raw material solution is sequentially coated, baked, cured and the like to form the cured first intermediate layer, the cured first intermediate layer is in direct contact with the first substrate layer, and the cured first intermediate layer is used as a buffer layer, so that the problems of large film thickness and complex multiple lamination processes caused by lamination of the adhesive buffer layer and the substrate layer can be avoided. In addition, in the composite film obtained by the preparation method, the buffer layer is in direct contact with the first substrate layer, so that the risk of separation (peeling) between adjacent layers in the bending process of the composite film is reduced. In addition, the preparation method can also avoid the problems of uneven lamination, easy generation of bubbles and the like in the conventional process of laminating the adhesive buffer layer and the substrate layer, and the composite film obtained by the method has good flatness, difficult existence of bubbles and high yield. And in the baking step, the raw material solution is pre-cured into the first intermediate layer, so that the surface of the first intermediate layer has certain initial viscosity, and the adhesion of the subsequent second substrate layer is facilitated. And after the second substrate layer is attached, the curing step is carried out, so that the first intermediate layer is further cured, contact connection between the first intermediate layer and the second substrate layer is enhanced, the obtained buffer layer is more tightly connected with the interface between the second substrate layer and the first substrate layer, and further, the risk of separation between adjacent layers in the bending process of the composite film is reduced.

In some embodiments, the step of applying the feedstock solution on the first substrate layer employs one of roller coating, gravure coating, knife coating, and slot coating. Specifically, the processes of roller coating, micro-concave coating, blade coating, slit coating and the like are mature, and the industrial production is facilitated.

In some embodiments, the step of pre-curing the stock solution into the first intermediate layer includes a gradient of elevated temperature over a temperature range of 60 ℃ to 120 ℃.

In some embodiments, in the curing step, the curing temperature is 45 ℃ or higher and the curing time is 72 hours or less. In this way, the adhesion between the second substrate layer and the first intermediate layer is made to reach a predetermined specification.

In some embodiments, after the curing step, further comprising disposing an adhesive layer on a surface of the first substrate layer remote from the cured first intermediate layer; or, an adhesive layer is arranged on the surface of the second substrate layer, which is far away from the cured first intermediate layer.

In some embodiments, the second substrate layer is directly attached to the surface of the first intermediate layer remote from the first substrate layer.

In some embodiments, the second substrate layer is provided with a through hole. Thus, the volatilized solvent is discharged in the curing step.

In some embodiments, the attaching step further comprises coating a raw material solution on the second substrate layer and baking to pre-cure the raw material solution on the second substrate layer into a second intermediate layer; in the attaching step, the second intermediate layer is attached to the first intermediate layer; in the curing step, the second intermediate layer is cured at the same time. In the preparation method, the first intermediate layer and the second intermediate layer are obtained by coating raw material solutions on the first substrate layer and the second substrate layer respectively and baking the raw material solutions respectively. Because the first intermediate layer and the second intermediate layer after baking all have certain initial viscosity, compared with the direct bonding of the first intermediate layer and the second substrate layer, the bonding of the first intermediate layer and the second intermediate layer is more compact, and the capability of the composite film for resisting the pressure impact can be further enhanced. In addition, after the lamination, the curing step is carried out, so that the first intermediate layer and the second intermediate layer are cured simultaneously, the process procedures can be reduced, and the cost is reduced. In addition, the first middle layer and the second middle layer are cured simultaneously, so that the uniformity of the performance of the whole film layer of the buffer layer can be ensured.

In some embodiments, the step of applying the feedstock solution onto the second substrate layer employs one of roller coating, gravure coating, knife coating, and slot coating. Specifically, the processes of roller coating, micro-concave coating, blade coating, slit coating and the like are mature, and the industrial production is facilitated.

In some embodiments, the step of pre-curing the stock solution on the second substrate layer to the second intermediate layer includes a gradient of elevated temperature over a temperature range of 60 ℃ to 120 ℃.

The second aspect of the present application provides a composite film, which comprises a first substrate layer, a buffer layer and a second substrate layer which are sequentially laminated, wherein the buffer layer is in direct contact with the surfaces of the first substrate layer and the second substrate layer, and the second substrate layer is provided with a through hole.

In some embodiments, the material of the buffer layer is one of a polyurethane-based elastomer, a polyamide-based elastomer, and a silicone-based elastomer.

In some embodiments, the material of the first substrate layer is polyethylene terephthalate or polyimide; the material of the second substrate layer is polyethylene terephthalate or polyimide.

In some embodiments, the composite film further comprises an adhesive layer on a surface of the first substrate layer remote from the buffer layer; alternatively, the adhesive layer is located on a surface of the second substrate layer remote from the buffer layer.

A third aspect of the present application provides a cover plate assembly comprising a cover plate, the cover plate being a composite membrane according to the second aspect; or the cover plate assembly comprises a cover plate and a protective layer arranged on the cover plate, wherein the protective layer is the composite film according to the second aspect.

Since the composite film according to the second aspect has an energy absorbing and damping effect, both as a cover plate and a protective layer, a cover plate assembly using the same has the advantages of anti-extrusion and impact resistance. In addition, since the thickness of the composite film according to the second aspect is reduced, the cover plate assembly using the same is also reduced in thickness.

A fourth aspect of the present application provides a display screen, which includes a cover plate assembly and a display assembly that are sequentially stacked, where the cover plate assembly is a cover plate assembly according to the third aspect.

The display screen provided in the fourth aspect of the present application may be rigid or flexible and foldable. Since it includes the cap plate assembly according to the third aspect, it has superior anti-extrusion and impact resistance properties and is thin in thickness.

A fifth aspect of the present application provides a display screen, comprising a cover plate assembly, a display assembly, and a support assembly, which are sequentially stacked, wherein the display screen is flexible; at least one of the cover plate assembly and the support assembly comprises a composite membrane according to the second aspect; when the cover plate component comprises a composite membrane, the cover plate component comprises a cover plate, and the cover plate is the composite membrane; or the cover plate component comprises a cover plate and a protective layer arranged on the cover plate, and the protective layer is a composite film.

The display screen provided in the fifth aspect of the present application is flexible, and because it includes the composite film described in the second aspect, it has the advantages of better anti-extrusion and anti-impact properties, and thin thickness, and so on, and will not be described herein.

A sixth aspect of the present application provides an electronic device, which includes a housing and a display screen mounted on the housing, where the display screen is the display screen according to the fourth aspect or the display screen according to the fifth aspect.

Drawings

Fig. 1 is a schematic structural diagram of an electronic device according to an embodiment of the disclosure.

Fig. 2 is a schematic structural diagram of the electronic device shown in fig. 1 in an folded state.

Fig. 3 is a schematic structural diagram of the electronic device shown in fig. 1 in an folded-out state.

Fig. 4 is a schematic structural diagram of a display screen of the electronic device shown in fig. 1.

Fig. 5A and 5B are schematic structural views of composite films according to different embodiments, respectively.

Fig. 6A is a schematic structural diagram of a roller coating process in the preparation method of the composite film according to an embodiment of the present application.

Fig. 6B is a schematic structural diagram of a roller coating process in a method for preparing a composite film according to another embodiment of the present application.

Fig. 7A to 7E are schematic structural views of a cover plate assembly according to various embodiments of the present application.

Fig. 8A to 8C are schematic structural views of a support assembly according to various embodiments of the present application.

Description of main reference numerals:

electronic device 100

Display screen 10

Cover plate assemblies

11, 11a, 11b, 11c, 11d, 11e

Cover plate 111

Protective layer 112

Display assembly 12

Polarizing layer 121

Display panel 122

Back film 123

Support assemblies

13, 13a, 13b, 13c

Housing 20

Composite membranes

30a, 30b

First substrate layer 41

Second substrate layer 42

Buffer layer 50

Adhesive layer 60

Coating roller 70

Composite roller 80

Detailed Description

Currently, in a foldable electronic device, a foldable module (hereinafter, also referred to as a foldable display screen or a flexible display screen) generally includes a cover plate assembly, a display assembly, and a support assembly. The cover plate assembly is generally formed by attaching multiple layers of supporting base materials together through adhesive layers, and the front surface (also called a display surface) of the display assembly is protected. The display assembly is used for displaying images. The support component is positioned on one side of the display component far away from the cover board component so as to support the display component and protect the back surface of the display component. However, with the development of ultra-thin trend, the stacking thickness of the foldable module is required to be thinner and thinner, and accordingly, the reliability requirement is higher and higher, and the anti-extrusion and anti-impact capabilities of the foldable module are required to be improved.

In this regard, embodiments of the present application provide a composite membrane. The composite film comprises a first substrate layer, a buffer layer and a second substrate layer which are sequentially laminated, wherein the buffer layer is in direct contact with the surfaces of the first substrate layer and the second substrate layer, and the second substrate layer is provided with a through hole.

When the composite film is used in a foldable electronic device, the composite film can be used in a cover plate assembly, used as a cover plate or used as a protective film attached to the cover plate. The buffer layer has certain energy absorption and shock absorption effects, and can improve the extrusion resistance and shock resistance of the cover plate assembly, so that the extrusion resistance and shock resistance of the whole electronic device are improved. In addition, as the buffer layer is in direct contact with the surfaces of the first substrate layer and the second substrate layer in the composite film, compared with a conventional cover plate assembly, the adhesive between the substrate and the buffer layer is reduced, and the risk of separation (peeling) between adjacent layers of the composite film in the bending process is reduced. In addition, the thickness of the composite film is reduced due to the reduction of the thickness of at least two layers of laminating adhesives, so that the thickness of the whole cover plate assembly is also reduced, and the overall weight of the foldable module and the electronic device is further reduced. In addition, the cost is also reduced because at least two layers of laminating adhesive are reduced. Further, as at least two layers of laminating adhesive are reduced, creep crease of the foldable module is improved to a certain extent; and, the buffer layer is in direct contact with the surfaces of the first substrate layer and the second substrate layer, so that the dislocation quantity of the foldable module is reduced, and the width of the black edge of the whole machine is reduced.

In addition, when the composite film is used in a foldable electronic device, the composite film can also be used as a support component arranged on one side of the display component far away from the cover plate component so as to support the display component. Because in this complex film, the buffer layer all direct contact with the surface of first substrate layer and second substrate layer, compare with the supporting component such as the attached support substrate of glue film on the metal sheet or buffering bubble cotton of conventionality, this complex film has cancelled the metal sheet, has reduced the rebound force of collapsible module, has alleviateed module weight, and the material cost of complex film is lower in addition compared with the metal sheet. In addition, in the composite film, the buffer layer is in direct contact with the surfaces of the first substrate layer and the second substrate layer, so that the adhesive in the composite film is reduced, and the risk of separation between adjacent layers of the composite film in the bending process is reduced. In addition, the thickness of the laminating adhesive is reduced, so that the thickness of the composite film is reduced, the thickness of the whole supporting component is also reduced, and the whole weight of the foldable module and the electronic device is further reduced. In addition, as the laminating adhesive is reduced, the creep crease of the foldable module is improved to a certain extent; and, the buffer layer is in direct contact with the surfaces of the first substrate layer and the second substrate layer, so that the dislocation quantity of the foldable module is reduced, and the width of the black edge of the whole machine is reduced.

It will be appreciated that the composite film may also be used in non-foldable electronic devices, for example, the composite film may be used in a cover sheet assembly, as a cover sheet, or as a protective film attached to a cover sheet. In the composite film, the buffer layer has certain energy absorption and shock absorption effects, so that the extrusion resistance and shock resistance of the cover plate assembly can be improved, and further the extrusion resistance and shock resistance of the whole electronic device are improved. In addition, as the buffer layer is in direct contact with the surfaces of the first substrate layer and the second substrate layer in the composite film, compared with a conventional cover plate assembly, the adhesive between the substrate and the buffer layer is reduced, and the risk of separation (peeling) between adjacent layers of the composite film in the bending process is reduced. In addition, the thickness of the composite film is reduced due to the reduction of the thickness of at least two layers of laminating adhesives, so that the thickness of the whole cover plate assembly is also reduced, and the overall weight of the foldable module and the electronic device is further reduced. In addition, the cost is also reduced because at least two layers of laminating adhesive are reduced.

In addition, the embodiment of the application also provides a preparation method of the composite film. In some embodiments, the method of making the composite film comprises: coating a raw material solution on the first substrate layer, wherein the raw material solution is one of a raw material solution of polyurethane elastomer, a raw material solution of polyamide elastomer and a raw material solution of polysiloxane elastomer; baking to pre-cure the raw material solution into a first intermediate layer; bonding, namely bonding the second substrate layer directly to the surface of the first intermediate layer far away from the first substrate layer; and curing the first intermediate layer to obtain a composite film, wherein the cured first intermediate layer is the buffer layer.

In the preparation method, the buffer layer is formed by sequentially coating, baking, curing and other steps by taking the raw material solution as the raw material solution, and the buffer layer is in direct contact with the surfaces of the first substrate layer and the second substrate layer, so that the problems of large film thickness and complex multiple lamination processes caused by laminating the adhesive buffer layer and the substrate layer can be avoided. In addition, in the composite film obtained by the preparation method, the buffer layer is in direct contact with the surfaces of the first substrate layer and the second substrate layer, so that the risk of separation (peeling) between adjacent layers in the bending process of the composite film is reduced. In addition, the preparation method can also avoid the problems of uneven lamination, easy generation of bubbles and the like in the conventional process of laminating the adhesive buffer layer and the substrate layer, and the composite film obtained by the method has good flatness, difficult existence of bubbles and high yield. In addition, in the preparation method, the raw material solution is pre-cured into the first intermediate layer in the baking step, so that the surface of the first intermediate layer has certain initial viscosity, and the subsequent attachment of the second substrate layer is facilitated. And after the second substrate layer is attached, the curing step is carried out, so that the first intermediate layer is further cured, contact connection between the first intermediate layer and the second substrate layer is enhanced, the obtained buffer layer is more tightly connected with the interface between the second substrate layer and the first substrate layer, and further, the risk of separation between adjacent layers in the bending process of the composite film is reduced. In some embodiments, through holes may also be provided in the second substrate layer to facilitate removal of solvent volatilized during the curing step.

In other embodiments, the attaching step further comprises coating the raw material solution on the second substrate layer; and baking to pre-cure the raw material solution on the second substrate layer into a second intermediate layer. In the attaching step, the second intermediate layer is attached to the first intermediate layer; in the curing step, the second intermediate layer is cured at the same time; the buffer layer further includes the second intermediate layer after curing. In the preparation method, the first intermediate layer and the second intermediate layer are obtained by coating raw material solutions on the first substrate layer and the second substrate layer respectively and baking the raw material solutions respectively. Because the first intermediate layer and the second intermediate layer after baking all have certain initial viscosity, compared with the direct bonding of the first intermediate layer and the second substrate layer, the bonding of the first intermediate layer and the second intermediate layer is more compact, and the capability of the composite film for resisting the pressure impact can be further enhanced. In addition, after the lamination, the curing step is carried out, so that the first intermediate layer and the second intermediate layer are cured simultaneously, the process procedures can be reduced, and the cost is reduced. In addition, the first middle layer and the second middle layer are cured simultaneously, so that the uniformity of the performance of the whole film layer of the buffer layer can be ensured. Also, in some embodiments, through holes may be provided in the second substrate layer to facilitate removal of the solvent volatilized during the baking and curing steps.

The following description of the technical solutions in the embodiments of the present application will be made clearly and completely with reference to the drawings in the embodiments of the present application, and it is apparent that the described embodiments are only some embodiments of the present application, not all embodiments.

Fig. 1 is a schematic structural diagram of an electronic device according to an embodiment of the disclosure. As shown in fig. 1, the electronic device 100 includes a housing 20 and a display screen 10 mounted to the housing 20. The electronic device 100 is flexible and foldable. The electronic device 100 is, for example, a foldable mobile phone or a foldable tablet computer, but not limited thereto. The housing 20 is used to mount and carry the display screen 10. In some embodiments, housing 20 includes, for example, but not limited to, two portions connected by a hinge (not shown) that allows the two portions of housing 20 to rotate relative to each other.

Fig. 2 is a schematic structural diagram of the electronic device shown in fig. 1 in an folded state. As shown in fig. 2, the electronic device 100 may be an in-folded electronic device. The display 10 has the property of being flexible and bendable. When the electronic device 100 is in the folded state, the display screen 10 is hidden inside the case 20 after being folded, and the case 20 is exposed outside as an exterior member that can be directly observed by a user.

Fig. 3 is a schematic structural diagram of the electronic device shown in fig. 1 in an folded-out state. As shown in fig. 3, the electronic device 100 may also be an out-folded electronic device. The display screen 10 is flexible and foldable. When the electronic device 100 is in the folded state, the display screen 10 is folded and then exposed outside the housing 20, and the housing 20 is a non-exterior part.

Fig. 4 is a schematic structural diagram of a display screen of the electronic device shown in fig. 1. As shown in fig. 4, the display screen 10 includes a cover plate assembly 11, a display assembly 12, and a support assembly 13 stacked in order. The display assembly 12 is used for realizing a display function, and a side of the display assembly, which is close to the cover plate assembly 11, is a display side. The cover assembly 11 covers the display side of the display assembly 12 for a user to touch and protects the display assembly 12. The supporting component 13 is located on a side of the display component 12 away from the display side, and is used for supporting and protecting the display component 12, so that the electronic device can maintain a good form in different opening and closing states.

Specifically, the display module 12 includes a polarizing layer 121, a display panel 122, and a back film 123, which are laminated in this order. The polarizing layer 121 is located at the light emitting side of the display panel 122, and can reduce interference of external ambient light. The polarizing layer 121 includes, for example, a linearly polarized light layer (not shown) and a quarter-phase retardation plate (not shown) which are stacked. The quarter-phase retarder is capable of generating a phase retardation of an odd multiple of pi/2, and converting incident linearly polarized light into elliptically polarized light. If the light vector of the incident linearly polarized light forms +/-45 degrees with the wave plate fast and slow axis, circularly polarized light is obtained. Specifically, the linear polarization layer is, for example, a horizontal linear polarization layer, when external natural light is incident on the horizontal linear polarization layer and then converted into horizontal linear polarization, the horizontal linear polarization is converted into circular polarization by a quarter-phase retardation plate, the circular polarization is reflected by the display panel 122 and then becomes circular polarization with opposite rotation directions (such as left-handed circular polarization becomes right-handed circular polarization), the right-handed circular polarization is reflected by the display panel 122 and then becomes vertical linear polarization with a vibration direction perpendicular to the polarization direction of the horizontal linear polarization layer by the quarter-phase retardation plate, and the horizontal linear polarization layer cannot be transmitted. In this way, the polarizing layer 121 suppresses interference of external ambient light.

The display panel 122 is a flexible (or foldable) display panel. The display panel 122 is, for example, an Organic Light-Emitting Diode (OLED) display panel, a Micro Light-Emitting Diode (Micro LED) display panel, a Mini Light-Emitting Diode (Mini LED) display panel, or a quantum dot electroluminescent display panel, but is not limited thereto. The back film 123 is located on a side of the display panel 122 facing away from the display surface thereof to provide a certain supporting effect to the display panel 122. The material of the back film 123 may be an organic material, for example, polyimide, acrylic, epoxy, polyethylene terephthalate, polymethyl methacrylate, polyethylene, or the like. The back film 123 may be attached to the display panel 122 by an adhesive (not shown). The adhesive is, for example, a photo-setting adhesive or a thermosetting adhesive, but is not limited thereto.

In other embodiments, the polarizing layer 121 is omitted, and the display panel 122 is an OLED display panel without a polarizer (POL-leave), which is also called COE (Color filter On Encapsulation) structure OLED display panel. Thus, the display panel 122 is lighter and thinner, and is more suitable for being applied in the foldable electronic device 100.

Since the foldable electronic device 100 is required to bend the display 10 frequently, and the stacked thickness of the display 10 is required to be thinner and thinner with the development of ultra-thin trend, the reliability requirement is required to be higher and higher, and the anti-extrusion and anti-impact capabilities of the display 10 are required to be improved. In this regard, a composite membrane is provided in embodiments of the present application. The composite film can be used in a cover plate assembly 11 or a support assembly 13 in the display screen 10 to improve the impact resistance of the display screen 10. Fig. 5A and 5B are schematic structural views of composite films according to different embodiments, respectively. As shown in fig. 5A, the composite film 30a includes a first base material layer 41, a buffer layer 50, and a second base material layer 42 stacked in this order, and the buffer layer 50 is in direct contact with the surfaces of both the first base material layer 41 and the second base material layer 42.

The material of the first substrate layer 41 is, for example, transparent polyethylene terephthalate (polyethylene glycol terephthalate, PET) or transparent polyimide (Colorless Polyimide, CPI). Also, the material of the second substrate layer 42 is, for example, PET or CPI. Among them, PET has excellent creep resistance, fatigue resistance and dimensional stability, and good folding endurance. CPI also has a strong resistance to deformation. In addition, the CPI has better toughness, the elongation at break (the ratio of the elongation length to the length before stretching when the material is subjected to tension to break) can reach 15-40%, and the CPI can be well suitable for bending scenes.

The material of the buffer layer 50 is one of polyurethane-based elastomer, polyamide-based elastomer and polysiloxane-based elastomer.

In some embodiments, the material of the cushioning layer 50 is a thermoplastic polyurethane-based elastomer (Thermoplastic polyurethanes, TPU). TPU has excellent properties that are not comparable to other types of thermoplastic elastomers. Concretely, the TPU has the characteristics of excellent wear resistance, tear resistance, bending property, high tensile strength and elongation at break, low temperature resistance of-40 ℃ and high temperature resistance of more than 120 ℃, low long-term compression deformation rate, oil resistance, aliphatic hydrocarbon solvent resistance, aging resistance and the like, and is resistant to oxygen and ozone. TPU is a novel environment-friendly material between rubber and plastic, the elastic modulus of the TPU is between the rubber and the plastic, the elastic modulus of the rubber is usually between l and 10Mpa, and the TPU is between 10Mpa and 1000Mpa. The plastic (such as nylon) is more than 10000 Mpa. The hardness range of TPU is quite broad and has high elasticity throughout the hardness range. In addition, the TPU material has extremely excellent impact strength which is more than l000 MPa; the tensile strength of the TPU material reaches 50Mpa, and the tensile elongation can reach more than 500%; the elasticity is good and is several times higher than that of rubber; and the TPU material has good surface finish. In summary, when the TPU is used as the buffer layer 50, the TPU has better energy absorption and shock absorption effects, so that when the composite film 30a is applied to the display screen 10, the anti-falling performance, anti-extrusion and anti-impact performance of the display screen 10 can be improved, and the damage to the display screen 10 caused by external impact can be buffered. Furthermore, the TPU is softer and in direct contact with the first and second substrate layers 41 and 42, so that the composite film 30a has better conformability and anti-warping properties, and creep creases when the composite film 30a is applied to the display 10 can be improved when the display 10 is folded.

In other embodiments, the buffer layer 50 is a thermoplastic polyamide-based elastomer (Thermoplastic Polyamide, TPA). Among them, polyamide (PA), commonly called nylon. TPA uses polyamide as hard segment and polyether or polyester with low glass transition temperature Tg value as soft segment. The polyamide component may be

nylon

6, 66, 610, 11, 12, etc., but nylon 6 or 12 is an important part. The component of the soft segment is a long-chain polyol of polyether glycol or polyester glycol. The ratio and type of the hard segment and the soft segment are the ones that have the greatest influence on the physical properties of TPA. As the soft segment increases, its elongation becomes longer and the stress becomes smaller. TPA has good processing formability (good rule-to-rule) and nylon-like toughness and abrasion resistance. Therefore, when TPA is used as the buffer layer 50, it may also have a certain energy-absorbing and shock-absorbing effect, so that the composite film 30a may improve the anti-falling performance, anti-extrusion and anti-impact performance of the display screen 10 and buffer the damage of external impact to the display screen 10 when applied to the display screen 10.

In still other embodiments, the cushioning layer 50 is a silicone-based elastomer. The silicone elastomer is, for example, silica gel. The silica gel as the buffer layer 50 can improve the impact resistance of the display screen 10, and meanwhile, the material source is wide and the cost is low.

As shown in fig. 5B, the composite film 30B differs from the composite film 30a shown in fig. 5A in that: composite film 30b also includes an adhesive layer 60. The adhesive layer 60 is located on the surface of the second substrate layer 42 remote from the first substrate layer 41. The material of the adhesive layer 60 is, for example, a pressure-sensitive adhesive (Pressure Sensitive Adhesive, PSA) or an optically transparent adhesive (Optically Clear Adhesive, OCA), but is not limited thereto.

It will be appreciated that the composite film 30b may further include a release layer (not shown) located on a side of the adhesive layer 60 remote from the second substrate layer 42. In attaching the composite film 30b to the component to be attached (e.g., the display assembly 12 or the cover 111, below), the release layer is peeled off, and then the composite film 30b is bonded to the component to be attached through the adhesive layer 60. In comparison to the composite film 30b, the composite film 30a may not include a release layer, and when the composite film 30a is attached to an element to be attached (such as the display assembly 12 or the cover plate 111 below), an additional adhesive layer is provided to adhere the composite film 30a to the element to be attached.

The embodiment of the application also provides a preparation method of the composite film. The method may produce the composite film 30a or the composite film 30b described above. Specifically, the preparation method comprises the following steps.

Step S1: the first substrate layer is coated with a raw material solution.

The material of the first substrate layer may be PET or CPI. The raw material solution is one of a raw material solution of polyurethane elastomer, a raw material solution of polyamide elastomer and a raw material solution of polysiloxane elastomer.

In some embodiments, the material of the buffer layer is TPU and the stock solution is a stock solution of a polyurethane elastomer. Specifically, the raw material solution can be a solution in which the TPU is completely dissolved, and the solution can be synthesized by small molecular polyalcohol, and at least one of an anti-ultraviolet auxiliary agent, an antifoaming agent, a leveling agent, a curing agent, a cosolvent and the like is optionally added. Alternatively, the feed solution may include TPU particles and a solvent. The solvent is, for example, dimethylformamide (DFM). The TPU particles are dissolved by the DFM solvent to dilute to the appropriate concentration.

In other embodiments, the material of the buffer layer is TPA and the stock solution is a stock solution of a polyamide elastomer comprising PA, a curing agent, and a solvent. The solvent may be at least one of esters, alcohols and ketones, but is not limited thereto.

In still other embodiments, the material of the buffer layer is a silicone-based elastomer, and the stock solution of the silicone-based elastomer is, for example, a solution of silica gel.

Step S2: baking to pre-cure the raw material solution into a first intermediate layer.

In step S2, the first substrate layer coated with the raw material solution (i.e., the raw material solution of the polyurethane-based elastomer, the raw material solution of the polyamide-based elastomer, or the raw material solution of the polysiloxane-based elastomer in step S1) may be baked in a zoned temperature baking oven, and gradually heated up in a temperature range of 60 to 120 ℃, and then gradually cooled down.

Specifically, the gradient heating can be performed by taking 10 ℃ as a temperature gradient, namely, the heating process is 60-70-80-90-100-110-120 ℃. From warming to cooling to room temperature, the total time was 3 minutes. In other embodiments, the gradient heating may be performed by using a temperature gradient of 5 ℃, 15 ℃, 20 ℃, 25 ℃ or the like, but is not limited thereto. Wherein, the smaller the temperature gradient, the more uniform the raw material solution is pre-cured, but the process is complicated; the larger the temperature gradient is, the less the adjustment times are, and the process is simplified. In addition, in other embodiments, the time from heating up to cooling down can also be adjusted according to the thickness of the first intermediate layer to be formed, and the thicker the thickness of the first intermediate layer to be formed, the longer the time required.

In addition, in step S2, the air volume can be adjusted according to whether the temperature of the temperature sensor in the oven meets the target requirement and whether the temperature of the incubator is uniform. Further, the proportion of the curing agent in the raw material solution may be adjusted according to whether the curing in step S2 is complete.

Therefore, in step S2, the raw material solution is primarily cured under the action of the temperature gradient, the baking time, the air quantity, the proportion of the curing agent and other parameters, so that the surface of the raw material solution is kept to have a certain initial viscosity.

Step S3: and bonding the second substrate layer to one side of the first intermediate layer far away from the first substrate layer, curing the first intermediate layer, and curing the first intermediate layer to obtain the composite film.

Specifically, the curing treatment is used to bring the adhesion between the second substrate layer and the first intermediate layer to a predetermined specification. In the curing step, the curing temperature is greater than or equal to 45 ℃ and the curing time is less than or equal to 72 hours, so that the completion degree of the crosslinking reaction (such as the crosslinking reaction in the TPU) in the raw material solution is ensured, and the first intermediate layer (and/or the second intermediate layer) is thoroughly cured. For example, the curing temperature is 45℃and the curing time is 72 hours. In other embodiments, the curing temperature may be increased and the curing time reduced, for example, the curing temperature may be 50 ℃ to 60 ℃ and the curing time may be 48 hours to 60 hours.

In some embodiments, in step S3, the second substrate layer is directly attached to the surface of the first intermediate layer away from the first substrate layer, and after curing, the cured first intermediate layer is a buffer layer. In the preparation method, the second substrate layer is attached and then cured, so that the first intermediate layer is further cured, contact connection between the first intermediate layer and the second substrate layer is enhanced, the obtained buffer layer is more tightly connected with the interface between the second substrate layer and the first substrate layer, and further the risk of separation between adjacent layers in the bending process of the composite film is reduced. Wherein, the second substrate layer can be provided with through holes so as to be beneficial to discharging the volatilized solvent in the curing step.

In the preparation method, the buffer layer is formed by sequentially coating, baking, curing and other steps by taking the raw material solution as the raw material solution, and the buffer layer is in direct contact with the surfaces of the first substrate layer and the second substrate layer, so that the problems of large film thickness and complex multiple lamination processes caused by laminating the adhesive buffer layer and the substrate layer can be avoided. In addition, in the composite film obtained by the preparation method, the buffer layer is in direct contact with the surfaces of the first substrate layer and the second substrate layer, so that the risk of separation between adjacent layers in the bending process of the composite film is reduced. In addition, the preparation method can also avoid the problems of uneven lamination, easy generation of bubbles and the like in the conventional process of laminating the adhesive buffer layer and the substrate layer, and the composite film obtained by the method has good flatness, difficult existence of bubbles and high yield. In addition, in the preparation method, the raw material solution is pre-cured into the first intermediate layer in the baking step, so that the surface of the first intermediate layer has certain initial viscosity, and the subsequent attachment of the second substrate layer is facilitated. And after the second substrate layer is attached, the curing step is carried out, so that the first intermediate layer is further cured, contact connection between the first intermediate layer and the second substrate layer is enhanced, the obtained buffer layer is more tightly connected with the interface between the second substrate layer and the first substrate layer, and further, the risk of separation between adjacent layers in the bending process of the composite film is reduced.

In other embodiments, before step S3, the method further includes a step of coating the above-mentioned raw material solution on the second substrate layer, and baking the second substrate layer coated with the above-mentioned raw material solution, so as to pre-cure the raw material solution on the second substrate layer into a second intermediate layer. In this case, in step S3, the second intermediate layer on the second base material layer is bonded to the first intermediate layer on the first base material layer. In the curing treatment, the first intermediate layer and the second intermediate layer are cured simultaneously. The buffer layer includes a cured first intermediate layer and a cured second intermediate layer. In this case, the step of coating the raw material solution on the second substrate layer may refer to the step S1, and the step of baking the second substrate layer coated with the raw material solution may refer to the step S2, which will not be described herein. The second substrate layer may also be provided with through holes to facilitate the removal of the solvent volatilized during the baking step and the curing step.

In the preparation method, the first intermediate layer and the second intermediate layer are obtained by coating raw material solutions on the first substrate layer and the second substrate layer respectively and baking the raw material solutions respectively. Because the first intermediate layer and the second intermediate layer after baking all have certain initial viscosity, compared with the direct bonding of the first intermediate layer and the second substrate layer, the bonding of the first intermediate layer and the second intermediate layer is more compact, and the capability of the composite film for resisting the pressure impact can be further enhanced. In addition, after the lamination, the curing step is carried out, so that the first intermediate layer and the second intermediate layer are cured simultaneously, the process procedures can be reduced, and the cost is reduced. In addition, the first middle layer and the second middle layer are cured simultaneously, so that the uniformity of the performance of the whole film layer of the buffer layer can be ensured. Also, in some embodiments, through holes may be provided in the second substrate layer to facilitate removal of the solvent volatilized during the baking and curing steps.

Step S4: and attaching a protective film to the composite film, slitting and rolling. Specifically, slitting and winding can be performed on a slitting machine and a winding machine respectively. And step S4, after winding, the method can further comprise the steps of aging and the like, and then a finished product is obtained.

In addition, the preparation method of the composite film 30b further includes providing an adhesive layer on a surface of the second substrate layer away from the buffer layer and providing a release layer on the adhesive layer between the step S3 and the step S4, compared with the preparation method of the composite film 30 a. In other examples, an adhesive layer may be disposed on a surface of the second substrate layer away from the buffer layer between the step S3 and the step S4, and a release layer may be disposed on the adhesive layer.

In addition, in the above preparation method, the coating process in which the raw material solution is coated on the first substrate layer or the raw material solution is coated on the second substrate layer may be one of roller coating, gravure coating, doctor blade coating and slit coating. Specifically, the processes of roller coating, micro-concave coating, blade coating, slit coating and the like are mature, and the industrial production is facilitated.

As shown in fig. 6A, in some embodiments, a raw material solution (not shown) is coated on the first substrate layer 41 using a coating roller 70, and after baking, the raw material solution is pre-cured into a first intermediate layer (not shown). The composite roller 80 directly attaches the second substrate layer 42 to the side of the first substrate layer 41 having the first intermediate layer, and then, after the curing step, the composite film is obtained. The composite film includes a laminated first base material layer 41, a cured first intermediate layer, and a second base material layer 42. Wherein the cured first intermediate layer is the buffer layer 50.

In other embodiments, as shown in fig. 6B, a coating roller 70 may be used to apply a raw material solution (not shown) to the first substrate layer 41 and the second substrate layer 42, respectively. Then, the raw material solutions on the first substrate layer 41 and the second substrate layer 42 are baked, respectively, so that the raw material solutions on the first substrate layer 41 and the second substrate layer 42 are pre-cured into a first intermediate layer (not shown) and a second intermediate layer (not shown), respectively. Then, the side of the second substrate layer 42 having the second intermediate layer is bonded to the side of the first substrate layer 41 having the first intermediate layer by using the composite roller 80, and then the composite film is obtained after the curing step. The composite film includes a laminated first base material layer 41, a cured first intermediate layer, a cured second intermediate layer, and a second base material layer 42. Wherein the cured first intermediate layer and the cured second intermediate layer are buffer layers 50.

The composite film 30a and the composite film 30b described above may be applied to a cap plate assembly. Fig. 7A to 7E are schematic structural views of a cover plate assembly according to various embodiments of the present application.

As shown in fig. 7A, the cover plate assembly 11a includes a laminated cover plate 111 and an adhesive layer 60. The cover plate 111 is the composite film 30a described above. The material of the adhesive layer 60 is, for example, PSA or OCA, but is not limited thereto. When the cover plate assembly 11a is attached to the display assembly 12, an adhesive layer 60 may be disposed on the composite film 30a, such that the composite film 30a is adhered to the display assembly 12 through the adhesive layer 60.

It will be appreciated that adhesive layer 60 may also be provided on display assembly 12, in which case cover assembly 11 may include only composite film 30a and no adhesive layer 60.

Because the composite film 30a can be directly used as the cover plate 111, the buffer layer 50 in the composite film 30a has a certain energy absorption and shock absorption function, so that the anti-extrusion and shock resistance of the cover plate assembly 11 can be improved, and further, the anti-extrusion and shock resistance of the whole electronic device can be improved. Moreover, in the composite film, the buffer layer 50 is in direct contact with the surfaces of the first substrate layer 41 and the second substrate layer 42, so that compared with the conventional cover plate assembly 11, the adhesive between the substrate and the buffer layer 50 is reduced, and the risk of separation (peeling) between adjacent layers in the bending process of the composite film is reduced. In addition, the thickness of the composite film is reduced due to the reduction of the thickness of at least two layers of laminating adhesives, so that the thickness of the whole cover plate assembly 11a is also reduced, and the weight of the whole display screen and the electronic device is further reduced. In addition, the cost is also reduced because at least two layers of laminating adhesive are reduced. Further, as at least two layers of laminating adhesive are reduced, creep crease of the foldable module is improved to a certain extent; in addition, the buffer layer 50 is in direct contact with the surfaces of the first substrate layer 41 and the second substrate layer 42, so that the dislocation amount of the foldable module is reduced, and the width of the black edge of the whole machine is reduced.

Specifically, in the cap plate assembly 11a, the thicknesses of the first substrate layer 41 and the second substrate layer 42 are 25 μm to 500 μm (e.g., 25 μm to 30 μm, 30 μm to 40 μm, 40 μm to 50 μm, 50 μm to 60 μm, 60 μm to 70 μm, 70 μm to 80 μm, 80 μm to 90 μm, 90 μm to 100 μm, 100 μm to 150 μm, 150 μm to 200 μm, 200 μm to 250 μm, 250 μm to 300 μm, 300 μm to 350 μm, 400 μm to 450 μm, 450 μm) and the thicknesses of the buffer layer 50 are 30 μm to 500 μm (e.g., 30 μm to 40 μm, 40 μm to 50 μm, 50 μm to 60 μm, 60 μm to 70 μm, 70 μm to 80 μm, 80 μm to 90 μm, 90 μm to 100 μm, 150 μm to 200 μm, 200 μm to 250 μm, 300 μm to 350 μm, 350 μm to 400 μm, 400 μm to 500 μm, 50 μm to 50 μm, 50 μm to 60 μm, 60 μm to 70 μm, 70 μm to 80 μm, 80 μm to 90 μm, 100 μm to 100 μm, 150 μm to 200 μm, 200 μm to 400 μm, 300 μm to 500 μm). For example, the thickness of each of the first substrate layer 41 and the second substrate layer 42 is 50 μm, and the thickness of the buffer layer 50 is 30 μm. If the thickness of the first substrate layer 41 or the second substrate layer 42 is smaller than 50 μm, the strength and the hardness are relatively poor, which is not beneficial to the scratch resistance of the cover assembly 11a, whereas if the thickness of the first substrate layer 41 is larger than 500 μm, the thickness of the cover assembly 11a is relatively thicker, especially when the electronic device has an under-screen fingerprint structure, the thickness is too thick, which is possibly not beneficial to the sensitivity of fingerprint touch. Also, if the thickness of the buffer layer 50 is less than 30 μm, the energy absorption and shock absorption effects of the buffer layer 50 are relatively poor, and if the thickness of the buffer layer 50 is greater than 500 μm, the thickness of the cover assembly 11a is relatively thick, especially when the electronic device has an under-screen fingerprint structure, the thickness is too thick, which may be detrimental to the sensitivity of fingerprint touch.

As shown in fig. 7B, the cover plate assembly 11B includes a cover plate 111. The cover plate 111 is the composite film 30b described above. When the cover assembly 11b is attached to the display assembly 12, the adhesive layer 60 of the composite film 30b may be adhered to the display assembly 12. Compared with the cover plate component 11a, when the cover plate component 11b is arranged on the display component 12, no additional adhesive layer is needed, and the manufacturing process is simplified. In addition, in the cover assembly 11b, the thicknesses of the first substrate layer 41, the buffer layer 50 and the second substrate layer 42 of the composite film 30b may be set to be equal to the thickness of the composite film 30a in the cover assembly 11a, which is not described herein.

As shown in fig. 7C, the cover assembly 11C includes a cover 111 and a protective layer 112 disposed on the cover 111. The protective layer 112 is a composite film 30a. The protective layer 112 is bonded to the cover 111 by the adhesive layer 60. The cover 111 is made of flexible material such as PET and CPI. In other embodiments, if the cover assembly 11c is applied to a non-foldable display screen, the cover 111 may be made of transparent glass in addition to flexible materials such as PET and CPI. The composite film 30a serves as the protective layer 112, which also has the energy absorption and shock absorption functions, can improve the anti-extrusion and shock resistance of the cover plate assembly 11c, and also has the advantages of reducing the thickness of the whole cover plate assembly 11c and reducing the cost, and will not be described again.

As shown in fig. 7D, the cover assembly 11D includes a cover 111 and a protective layer 112 disposed on the cover 111. The protective layer 112 is a composite film 30b. The adhesive layer 60 of the composite film 30b is adhered to the cover plate 111. Compared with the cover plate assembly 11c, the protective layer 112 in the cover plate assembly 11d is disposed on the cover plate 111 without an additional adhesive layer, thereby simplifying the process. In addition, the material of the cover 111 in the cover assembly 11d may refer to the cover assembly 11c, which is not described herein.

As shown in fig. 7E, the cover sheet assembly 11E includes a buffer layer 50, a first base material layer 41, and an adhesive layer 60, which are sequentially stacked. In the cover assembly 11e, the buffer layer 50 can serve as an outer surface of the cover assembly 11e for a user to touch, and the adhesive layer 60 is used for bonding with the display assembly 12.

The step of preparing the cover assembly 11e may be performed by obtaining the first substrate layer 41 having the first intermediate layer through the steps S1 and S2 in the above preparation method, then performing the curing step in the step S3, and obtaining the laminate of the buffer layer 50 and the first substrate layer 41, and then disposing the adhesive layer 60 on the first substrate layer 41.

It is understood that the adhesive layer 60 may also be disposed on the display assembly 12, in which case the cover assembly 11e may include only the buffer layer 50 and the first substrate layer 41, without including the adhesive layer 60. The cover plate assembly 11e further reduces a substrate layer compared to the cover plate assembly 11a, so that the thickness of the cover plate assembly 11e is further reduced, the weight is further reduced, the cost is further reduced, and the manufacturing process is further simplified.

It will be appreciated that the cover plate assembly 11 in fig. 4 may be any of the cover plate assemblies of fig. 7A to 7E. Of course, any of the cover assemblies of fig. 7A to 7E may be applied to a non-foldable display screen, and in this case, the display screen may include the cover assembly 11 and the display assembly 12, without including the supporting assembly.

In addition, the above-described composite film 30a and composite film 30b may also be applied to the support member 13. Fig. 8A to 8C are schematic structural views of a support assembly according to various embodiments.

As shown in fig. 8A, the support member 13a includes a laminated adhesive layer 60 and a composite film 30a. The material of the adhesive layer 60 is, for example, PSA or OCA, but is not limited thereto. When the support member 13a is attached to the display member 12, an adhesive layer 60 may be disposed on the composite film 30a, so that the composite film 30a is adhered to the display member 12 through the adhesive layer 60.

It will be appreciated that adhesive layer 60 may also be disposed on display assembly 12, in which case support assembly 13a may include only composite film 30a and no adhesive layer 60.

Because the composite membrane 30a can be directly used as the supporting component 13a, the buffer layer 50 in the composite membrane 30 is in direct contact with the surfaces of the first substrate layer 41 and the second substrate layer 42, compared with the conventional supporting component that the supporting substrate or the buffer foam is attached on the metal plate through the adhesive layer, the supporting component 13a eliminates the metal plate, reduces the rebound force of the foldable module, lightens the weight of the module, and has lower material cost compared with the metal plate. In addition, in the supporting component 13a, the buffer layer 50 is in direct contact with the surfaces of the first substrate layer 41 and the second substrate layer 42, so that the adhesive in the composite film 30a is reduced, and the risk of separating adjacent layers of the composite film 30a in the bending process is reduced. In addition, the thickness of the laminating adhesive is reduced, and the thickness of the composite film 30a is reduced, so that the thickness of the whole supporting assembly is reduced, and the weight of the foldable display screen and the whole electronic device is further reduced. In addition, as the laminating adhesive is reduced, the creep crease of the foldable display screen is improved to a certain extent; in addition, the buffer layer 50 is in direct contact with the surfaces of the first substrate layer 41 and the second substrate layer 42, so that the dislocation amount of the foldable display screen is reduced, and the whole black edge width is reduced.

Specifically, in the support member 13a, the thicknesses of the first substrate layer 41 and the second substrate layer 42 are 25 μm to 500 μm (e.g., 25 μm to 30 μm, 30 μm to 40 μm, 40 μm to 50 μm, 50 μm to 60 μm, 60 μm to 70 μm, 70 μm to 80 μm, 80 μm to 90 μm, 90 μm to 100 μm, 100 μm to 150 μm, 150 μm to 200 μm, 200 μm to 250 μm, 250 μm to 300 μm, 300 μm to 350 μm, 400 μm to 450 μm, 450 μm) and the thicknesses of the buffer layer 50 are 30 μm to 500 μm (e.g., 30 μm to 40 μm, 40 μm to 50 μm, 50 μm to 60 μm, 60 μm to 70 μm, 70 μm to 80 μm, 80 μm to 90 μm, 90 μm to 100 μm, 150 μm to 200 μm, 200 μm to 250 μm, 300 μm to 350 μm, 350 μm to 400 μm, 400 μm to 500 μm), and the thicknesses of the buffer layer 50 are 30 μm to 500 μm (e.g., 30 μm to 40 μm, 50 μm to 60 μm, 60 μm to 70 μm, 70 μm to 80 μm, 80 μm to 90 μm, 90 μm to 100 μm, 150 μm to 200 μm, 150 μm to 400 μm, 400 μm to 400 μm, 300 μm to 500 μm, and 50 μm to 500 μm). For example, the thickness of each of the first substrate layer 41 and the second substrate layer 42 is 25 μm, and the thickness of the buffer layer 50 is 50 μm. If the thickness of the first substrate layer 41 or the second substrate layer 42 is smaller than 25 μm, the supporting strength of the display device 12 will be relatively poor, whereas if the thickness of the first substrate layer 41 is larger than 500 μm, the thickness of the supporting device 13a will be relatively thicker, which is not beneficial to the design of the electronic device. Also, if the thickness of the buffer layer 50 is less than 50 μm, the energy absorption and shock absorption effects of the buffer layer 50 are relatively poor, and if the thickness of the buffer layer 50 is greater than 500 μm, the thickness of the supporting component 13a is relatively thick, which is not beneficial to the design of the electronic device.

As shown in fig. 8B, the support member 13B is the above-described composite film 30B. When the support assembly 13b is attached to the display assembly 12, the adhesive layer 60 of the composite film 30b may be adhered to the display assembly 12. Compared with the supporting component 13a, the supporting component 13b is arranged on the display component 12 without an additional adhesive layer, so that the manufacturing process is simplified. In addition, in the support assembly 13b, the thicknesses of the first substrate layer 41, the buffer layer 50 and the second substrate layer 42 of the composite film 30b can be set to be equal to the thickness of the composite film 30a in the support assembly 13a, which is not described herein.

As shown in fig. 8C, the support member 13C includes a buffer layer 50, a first base material layer 41, and an adhesive layer 60, which are laminated in this order. In the support member 13c, the adhesive layer 60 is used for adhesion with the display member 12. The preparation steps of the supporting component 13c can refer to the cover component 11E in fig. 7E, which is not described herein.

It will be appreciated that adhesive layer 60 may also be disposed on display assembly 12, in which case support assembly 13c may include only buffer layer 50 and first substrate layer 41, without adhesive layer 60. Since the support component 13c is further reduced by one substrate layer compared with the support component 13a, the thickness of the support component 13c is further reduced, the weight is further reduced, the cost is further reduced, and the manufacturing process is further simplified.

It is understood that the support assembly 13 in fig. 4 may be any one of the support assemblies of fig. 8A to 8C.

In summary, the electronic device, especially the foldable electronic device, using the composite film of the embodiments of the present application can have improved extrusion resistance and impact resistance.

The above embodiments are only for illustrating the technical solution of the present application and not for limiting, and although the present application has been described in detail with reference to the above preferred embodiments, it should be understood by those skilled in the art that the technical solution of the present application may be modified or substituted without departing from the spirit and scope of the technical solution of the present application.

Claims

1. A method of preparing a composite membrane, comprising:

baking to pre-cure the raw material solution into a first intermediate layer;

bonding, namely bonding a second substrate layer to one side of the first intermediate layer away from the first substrate layer; and

2. The method of producing a composite film according to claim 1, wherein the step of coating the raw material solution on the first substrate layer employs one of roller coating, gravure coating, doctor blade coating and slit coating.

3. The method of producing a composite film according to claim 1, wherein the step of pre-curing the raw material solution into the first intermediate layer includes a gradient temperature increase in a temperature range of 60 ℃ to 120 ℃.

4. The method according to claim 1, wherein in the aging step, the aging temperature is 45 ℃ or higher and the aging time is 72 hours or less.

5. The method of producing a composite film according to claim 1, further comprising providing an adhesive layer on a surface of the first base material layer remote from the cured first intermediate layer after the curing step; or, an adhesive layer is arranged on the surface of the second substrate layer away from the cured first intermediate layer.

6. The method of any one of claims 1 to 5, wherein the second substrate layer is directly attached to a surface of the first intermediate layer remote from the first substrate layer.

7. The method of producing a composite film according to claim 6, wherein the second base material layer is provided with a through hole.

8. The method of producing a composite film according to any one of claims 1 to 5, wherein the bonding step is preceded by:

coating the raw material solution on the second substrate layer; and

baking to pre-cure the raw material solution on the second substrate layer into a second intermediate layer;

in the attaching step, the second intermediate layer is attached to the first intermediate layer;

in the curing step, the second intermediate layer is cured at the same time.

9. The method of producing a composite film according to claim 8, wherein the step of applying the raw material solution on the second substrate layer employs one of roller coating, gravure coating, doctor blade coating and slit coating.

10. The method of producing a composite film according to claim 8, wherein the step of pre-solidifying the raw material solution on the second base material layer into the second intermediate layer includes a gradient temperature increase in a temperature range of 60 ℃ to 120 ℃.

11. The composite film is characterized by comprising a first substrate layer, a buffer layer and a second substrate layer which are sequentially laminated, wherein the buffer layer is in direct contact with the surfaces of the first substrate layer and the second substrate layer, and the second substrate layer is provided with a through hole.

12. The composite film according to claim 11, wherein the material of the buffer layer is one of a polyurethane-based elastomer, a polyamide-based elastomer, and a polysiloxane-based elastomer.

13. The composite film according to claim 11 or 12, wherein the material of the first substrate layer is polyethylene terephthalate or polyimide; the material of the second substrate layer is polyethylene terephthalate or polyimide.

14. The composite film of any one of claims 11 to 13, further comprising an adhesive layer on a surface of the first substrate layer remote from the buffer layer; alternatively, the adhesive layer is located on a surface of the second substrate layer remote from the buffer layer.

15. A cover sheet assembly, characterized in that it comprises a cover sheet, which is a composite film according to any one of claims 11 to 14; or the cover plate assembly comprises a cover plate and a protective layer arranged on the cover plate, wherein the protective layer is a composite film according to any one of claims 11 to 14.

16. A display screen comprising a cover plate assembly and a display assembly stacked in sequence, wherein the cover plate assembly is according to claim 15.

17. The display screen is characterized by comprising a cover plate assembly, a display assembly and a support assembly which are sequentially stacked, wherein the display screen is flexible; at least one of the cover plate assembly and the support assembly comprising a composite membrane according to any one of claims 11 to 14; when the cover plate component comprises the composite membrane, the cover plate component comprises a cover plate, and the cover plate is the composite membrane; or the cover plate component comprises a cover plate and a protective layer arranged on the cover plate, wherein the protective layer is the composite film.

18. An electronic device comprising a housing and a display screen mounted to the housing, wherein the display screen is according to claim 16 or 17.