WO2023272500A1 - 光学胶及其制备方法、显示屏与终端设备 - Google Patents

光学胶及其制备方法、显示屏与终端设备 Download PDF

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Publication number
WO2023272500A1
WO2023272500A1 PCT/CN2021/103185 CN2021103185W WO2023272500A1 WO 2023272500 A1 WO2023272500 A1 WO 2023272500A1 CN 2021103185 W CN2021103185 W CN 2021103185W WO 2023272500 A1 WO2023272500 A1 WO 2023272500A1
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Prior art keywords
acrylate
urethane
layer
optical adhesive
optical
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PCT/CN2021/103185
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English (en)
French (fr)
Inventor
泽登纯一
徐焰
刘孔华
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华为技术有限公司
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Priority to PCT/CN2021/103185 priority Critical patent/WO2023272500A1/zh
Priority to CN202180099984.1A priority patent/CN117597408A/zh
Publication of WO2023272500A1 publication Critical patent/WO2023272500A1/zh

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/40—Layered products comprising a layer of synthetic resin comprising polyurethanes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/20—Adhesives in the form of films or foils characterised by their carriers
    • C09J7/22—Plastics; Metallised plastics
    • C09J7/25—Plastics; Metallised plastics based on macromolecular compounds obtained otherwise than by reactions involving only carbon-to-carbon unsaturated bonds

Definitions

  • the present application relates to the field of flexible screens, in particular to an optical adhesive, a preparation method thereof, a display screen and a terminal device.
  • the folding screen is mainly assembled by a flexible organic light-emitting diode (OLED) display and a hinge structure.
  • OLED organic light-emitting diode
  • the OLED display is mainly a laminated module composed of a transparent cover, polarizer, touch screen, display panel, etc., and the film layers are bonded by optical clear adhesive (OCA).
  • OCA optical clear adhesive
  • the traditional OCA is generally a single-layer acrylate adhesive, which is easy to form dislocation deformation after repeated bending of the folding screen, which makes the OCA often suffer from failures such as interface degumming, body damage and bubbles.
  • Some high-modulus and high-adhesion OCAs are not easy to be damaged on the glue body or interface, there is a problem that other film materials in the folding screen are likely to break due to high stress due to insufficient flexibility. Therefore, there is still a lack of an optical adhesive that is not easily damaged after repeated bending, and is not easy to be degummed from the bonding interface, and is not easy to break other film materials of the folding screen.
  • the application provides an optical glue and its preparation method, a display screen and a terminal device, so as to obtain an optical adhesive that is not easy to damage the main body after repeated bending, is not easy to fall off from the bonding interface, and is not easy to break the rigid film material of the folding screen.
  • Optical glue is not easy to damage the main body after repeated bending, is not easy to fall off from the bonding interface, and is not easy to break the rigid film material of the folding screen.
  • the present application provides an optical adhesive, which includes at least one support layer, and adhesive layers are provided on both sides of any support layer, wherein the support layer contains polyurethane polymer, polyurethane
  • the weight average molecular weight of the polymer is 2000-60000.
  • the optical glue provided by this application includes at least one support layer, the support layer is made of polyurethane polymer with a weight average molecular weight of 2000-60000 as the main material, which can achieve high flexibility and high recovery, and can effectively prevent OCA and folding screen Other rigid membranes are broken during bending, and at the same time, the OCA body is not easily damaged.
  • two opposite surfaces of the supporting layer are provided with adhesive layers, which can realize effective bonding with other film materials of the folding screen. Therefore, the OCA provided by the present application can combine the characteristics of high flexibility, high recovery, and high adhesiveness, and at the same time have more excellent bending resistance.
  • the urethane acrylate-acrylate in the optical glue of the present application has high light transmission, low haze and is not easy to yellow, and has excellent optical properties on the basis of good mechanical properties.
  • the polyurethane polymer includes a first polyurethane acrylate, the weight average molecular weight of the first polyurethane acrylate is 2000-20000, and the storage elastic modulus value E25 at 25 °C is 5-25. 80KPa.
  • Urethane acrylate with this performance has a high degree of flexibility and freedom. When subjected to external stress, it will deform freely and the stress will be released freely; when the external stress is removed, the deformation will recover in the opposite direction. Thus, it is beneficial to improve the elastic deformation ability of the optical adhesive, and improve the recoverability of the optical adhesive.
  • the storage modulus value E 25 of the first type of urethane acrylate at 25°C is >3 ⁇ 10 4 Pa
  • the storage modulus value E 60 at 60°C is >2 ⁇ 10 4 Pa
  • storage modulus value E -40 ⁇ 1 ⁇ 10 6 Pa at -40°C is >3 ⁇ 10 4 Pa
  • the storage modulus value E 60 at 60°C is >2 ⁇ 10 4 Pa
  • storage modulus value E -40 ⁇ 1 ⁇ 10 6 Pa at -40°C In order to improve the elastic deformation ability of the optical adhesive under different temperature application scenarios, and improve the recoverability of the optical adhesive under different temperature application scenarios.
  • the first urethane acrylate contains urethane acrylate bonds and hydrogen bonds.
  • the presence of urethane acrylate bonds and hydrogen bonds can help urethane acrylate form a helical network structure.
  • the urethane acrylate of this structure has a high degree of flexibility and freedom. When it is subjected to external stress, it will deform freely and the stress will be released freely; when the external stress is removed, the deformation will recover in the opposite direction. During this process, the main chain is less prone to plastic deformation, thereby providing high flexibility and high recovery.
  • the first urethane acrylate includes a urethane polymer.
  • the urethane polymer includes at least one of polyester urethane, polyether urethane, polycarbonate urethane or polypropylene urethane.
  • the polyurethane polymer includes a second polyurethane acrylate, the weight average molecular weight of the second polyurethane acrylate is 23,000-60,000, and the storage modulus value E25 at 25 °C is 100-100. 500KPa.
  • the second urethane acrylate with this performance can generate stronger cohesive force with the adhesive layer, thereby improving the adhesive force between the support layer and the adhesive layer, and effectively avoiding interlayer peeling inside the optical adhesive.
  • the storage modulus value E 25 of the second polyurethane acrylate at 25°C is >12 ⁇ 10 4 Pa
  • the storage modulus value E 60 at 60°C is >5 ⁇ 10 4 Pa
  • storage modulus value E -40 ⁇ 3 ⁇ 10 6 Pa at -40°C is >12 ⁇ 10 4 Pa
  • the elongation at break of the second urethane acrylate is greater than or equal to 200%, so as to improve the strain performance of the optical adhesive.
  • the weight ratio of the first urethane acrylate to the second urethane acrylate is 9:1-2:1, preferably 7:1-3:1, more preferably 5:1-3 :1.
  • the second urethane acrylate includes a urethane polymer.
  • the urethane polymer includes at least one of polyester urethane, polyether urethane, polycarbonate urethane or polypropylene urethane.
  • the total thickness of the support layer accounts for 30%-80% of the total thickness of the optical glue.
  • the optical adhesive can be made to have high flexibility and high recovery, and at the same time have high bonding performance.
  • the recovery rate of the supporting layer is >85%, which is beneficial to improve the recoverability of the optical adhesive.
  • the visible light transmittance of the supporting layer is >90%, the haze is ⁇ 2%, and the yellowing index is ⁇ 3. It is beneficial to improve the optical properties of optical glue.
  • the adhesive layer contains an acrylic adhesive.
  • the acrylic adhesive layer and the polyurethane acrylate have good adhesive properties, so as to improve the adhesive strength between the support layer and the adhesive layer.
  • the acrylate binder includes acrylate and/or (meth)acrylate containing hydroxyl groups.
  • the (meth)acrylate containing hydroxyl group includes 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl At least one of base (meth)acrylate, 4-hydroxycyclohexyl (meth)acrylate or 5-hydroxycyclohexyl (meth)acrylate.
  • the adhesive layer further includes at least one of the following copolymers, the copolymers include vinyl copolymers, silicone copolymers, olefin copolymers, polyurethane acrylate (methyl) Acrylate or polybutadiene di(meth)acrylate to further improve the adhesive performance of the adhesive layer.
  • the copolymers include vinyl copolymers, silicone copolymers, olefin copolymers, polyurethane acrylate (methyl) Acrylate or polybutadiene di(meth)acrylate to further improve the adhesive performance of the adhesive layer.
  • the present application also provides a preparation method of optical glue, the preparation method comprising: providing at least one support layer, and forming adhesive layers on both sides of any support layer; wherein, the support layer contains polyurethane polymer , The weight-average molecular weight of the polyurethane polymer is 2000-60000.
  • the preparation method of the optical adhesive provided by the application includes at least one support layer, and the support layer is made of polyurethane polymer with a weight average molecular weight of 2000-60000 as the main material, which can realize high flexibility And high resilience, which can effectively prevent OCA and other rigid film materials of the folding screen from breaking during bending, and at the same time, make the OCA body less prone to damage.
  • two opposite surfaces of the support layer are provided with bonding layers, which can realize effective bonding with other frictions of the folding screen. Therefore, the OCA provided by the present application can combine the characteristics of high flexibility, high recovery, and high adhesiveness, and at the same time have more excellent bending resistance.
  • the urethane acrylate in the optical glue of the present application has high light transmission, low haze and is not easy to yellow, and has excellent optical properties on the basis of good mechanical properties.
  • a polyurethane polymer slurry is formed.
  • an adhesive layer is respectively formed on both sides of any supporting layer, including:
  • the adhesive layer on the surface of the second release film is pasted on the surface of the supporting layer.
  • the steps of forming the adhesive layer and the support layer can be repeated to form alternately arranged multi-layer adhesive layers and multi-layer support layers. , such as two, three, four or more layers, etc.
  • forming an adhesive layer on both sides of any support layer includes: using a co-extrusion process to simultaneously co-extrude to form an adhesive layer and a support layer that are sequentially stacked.
  • the extrusion dies of the adhesive layer and the support layer can be designed according to the structure of the final formed OCA.
  • the outermost layer should ensure the co-extrusion adhesive layer.
  • the present application also provides a display screen, which includes a transparent cover plate, a polarizer, a touch screen and a display panel arranged in sequence, wherein, between the transparent cover plate and the polarizer, between the polarizer and the touch screen,
  • the optical glue of the first aspect of the present application is provided between the touch screen and the display panel.
  • the display screen of the present application includes the optical adhesive of the first aspect of the application, the display screen of the present application has higher application life.
  • the display screen is a flexible display screen.
  • the display screen may be a flexible folding screen.
  • the present application provides a terminal device, including the display screen in the third aspect of the present application.
  • the terminal device of the present application includes the display screen according to the third aspect of the present application, the terminal device of the present application also has the feature of long service life.
  • FIG. 1 is a schematic structural view of an optical adhesive according to an embodiment of the present application
  • FIG. 2 is a schematic structural view of an optical adhesive according to another embodiment of the present application.
  • FIG. 3 is a schematic structural view of an optical adhesive according to another embodiment of the present application.
  • Fig. 4 is a schematic flow chart of a preparation method of an optical adhesive according to an embodiment of the present application.
  • Fig. 5 is a schematic structural view of preparing a bonding layer in an embodiment of the present application.
  • Fig. 6 is a schematic structural view of preparing a support layer in an embodiment of the present application.
  • Figure 7 is a schematic structural view of preparing another layer of bonding layer in one embodiment of the present application.
  • Fig. 8 is a schematic structural diagram of optical glue prepared in an embodiment of the present application.
  • FIG. 9 is a schematic flowchart of a method for preparing an optical adhesive according to another embodiment of the present application.
  • the folding screen is mainly assembled by a flexible organic light-emitting diode (OLED) display and a hinge structure.
  • OLED organic light-emitting diode
  • the OLED display is mainly a laminated module composed of a transparent cover, polarizer, touch screen, display panel, etc., and the film layers are bonded by optical clear adhesive (OCA).
  • OCA optical clear adhesive
  • OCA is required to have the following characteristics: (1) Excellent flexible deformation capability, rigid film materials (transparent covers, polarizers, touch screens, etc.) in folding screens
  • the flexible deformation of OCA absorbs large dislocations and realizes bending; (2) has excellent deformation recovery ability, and has recovery ability after repeated large deformations, and does not cause plasticity, wrinkles, etc.
  • the interface (such as the surface of the transparent cover, polarizer, etc.) needs to have excellent bonding performance, and after repeated dislocation and deformation, there will be no failure such as degumming on the interface.
  • the common failure problem of folding screens is that after the OCA is bent (under different scenarios of normal temperature, low temperature or high temperature), the OCA interface peels off and the failure of bubbles occurs.
  • Existing OCAs usually have contradictions in the three characteristics of flexibility, recoverability and adhesive performance, and cannot be realized at the same time.
  • the modulus of OCA is low and the flexibility is high, the recovery and adhesion are insufficient, and plastic deformation is prone to occur, resulting in the destruction of the OCA body; when the modulus of OCA is high and the recovery is high, its flexibility is often insufficient and the stress is too large. Therefore, there is still a lack of an optical adhesive that is not easily damaged after repeated bending, and is not easy to be degummed from the bonding interface, and is not easy to break other film materials of the folding screen.
  • an embodiment of the present application provides an optical glue.
  • the terms used in the following examples are for the purpose of describing particular examples only, and are not intended to limit the application.
  • the singular expressions "a”, “an”, “”, “above”, “the” and “this” are intended to also include for example The expression “one or more” is used unless the context clearly indicates otherwise.
  • references to "one embodiment” or “some embodiments” or the like in this specification means that a particular feature, structure, or characteristic described in connection with the embodiment is included in one or more embodiments of the present application.
  • appearances of the phrases “in one embodiment,” “in some embodiments,” “in other embodiments,” “in other embodiments,” etc. in various places in this specification are not necessarily All refer to the same embodiment, but mean “one or more but not all embodiments” unless specifically stated otherwise.
  • the terms “including”, “comprising”, “having” and variations thereof mean “including but not limited to”, unless specifically stated otherwise.
  • FIG. 1 is a schematic structural view of an optical adhesive according to an embodiment of the present application.
  • the optical adhesive 10 may include at least one supporting layer 11 , and adhesive layers 12 are provided on both sides of any supporting layer 11 .
  • the number of layers of the support layer 11 can be one layer, the support layer 11 includes two oppositely arranged surfaces, and the two oppositely arranged surfaces of the support layer 11 are An adhesive layer 12 is provided.
  • FIG. 2 is a schematic structural diagram of an optical adhesive according to another embodiment of the present application.
  • the optical adhesive 10 may include two support layers 11, any one of the support layers 11 is provided with an adhesive layer 12 on two opposite surfaces, and adjacent An adhesive layer 12 can be used to bond the two supporting layers 11 .
  • FIG. 3 is a schematic structural diagram of an optical adhesive according to another embodiment of the present application.
  • the optical adhesive 10 may include three support layers 11, and two opposite surfaces of any support layer 11 are provided with adhesive layers 12, wherein the adjacent An adhesive layer 12 can be used to bond the two supporting layers 11 .
  • optical glue 10 of the embodiment of the present application can be set to four layers, two layers or three layers in addition to four layers, Five layers or more, no specific limitation here.
  • the supporting layer and the bonding layer are explained in detail below respectively.
  • the supporting layer 11 contains a polyurethane polymer, and the weight average molecular weight of the polyurethane polymer is 2,000-60,000.
  • the weight average molecular weight of the polyurethane polymer forming the supporting layer 11 may be, for example, 2000, 4000, 6000, 8000, 10000, 12000, 14000, 16000, 18000, 20000.
  • the above weight-average molecular weights are only for illustration, and are not specifically limited to polyurethane polymers.
  • the polyurethane polymer includes a first polyurethane acrylate, the weight average molecular weight of the first polyurethane acrylate is 2000-20000, and the storage modulus value E25 at 25 °C is 5 ⁇ 80KPa.
  • Storage modulus also known as elastic modulus, refers to the amount of energy stored due to elastic (reversible) deformation when a material is deformed, reflecting the elasticity of the material.
  • the support layer formed by polyurethane acrylate that meets the above conditions can effectively improve the elastic deformation ability of the optical adhesive and improve the recoverability of the optical adhesive. At the same time, it can effectively expand the application range of the optical adhesive so that it is not affected by the ambient temperature. and fail.
  • the first urethane acrylate contains urethane acrylate bonds and hydrogen bonds.
  • the presence of urethane acrylate bonds and hydrogen bonds can help urethane acrylate form a helical network structure.
  • the urethane acrylate of this structure has a high degree of flexibility and freedom. When it is subjected to external stress, it will deform freely and the stress will be released freely; when the external stress is removed, the deformation will recover in the opposite direction. During this process, the main chain is less prone to plastic deformation, thereby providing high flexibility and high recovery.
  • the support layer may also include a second urethane acrylate, the weight average molecular weight of the second urethane acrylate is 23000-60000, and the storage capacity at 25°C is The modulus value E 25 is 100-500KPa.
  • the storage modulus value E 25 of the second urethane acrylate at 25°C is >12 ⁇ 10 4 Pa
  • the storage modulus value E 60 at 60°C is >5 ⁇ 10 4 Pa
  • storage modulus value E -40 ⁇ 3 ⁇ 10 6 Pa at -40°C The elongation at break of the second urethane acrylate is ⁇ 200%.
  • the weight ratio of the first urethane acrylate to the second urethane acrylate is 9:1-2:1, preferably 7:1-3:1, more preferably 5:1-3:1 .
  • the flexibility, elastic deformation ability and recoverability of the optical adhesive can be improved, and the bonding strength inside the optical adhesive can also be improved.
  • the weight ratio of the first urethane acrylate to the second urethane acrylate is finalized but not limited to: 9:1, 8:1, 7:1, 6:1, 5:1, 4:1, 3: 1. 2:1.
  • the supporting layer formed by the first urethane acrylate and the second urethane acrylate can have higher flexibility, stronger elastic deformation ability and stronger recoverability; in addition, the obtained supporting layer can also have higher Excellent light transmittance, low haze and low yellowing index.
  • the recovery rate of the support layer can be >85%, preferably >88%, more preferably >90%; the visible light transmittance of the support layer is >90%, preferably >92%, more preferably >93%.
  • the haze of the supporting layer is ⁇ 2%, and the yellowing index is ⁇ 3.
  • test process of the recovery rate of the support layer 11 is as follows: at 25°C, apply a 400% strain and keep it for 10 minutes, then remove the stress and recover naturally for 10 minutes, and test the residual strain value of the support layer after 10 minutes.
  • the calculation formula is as follows:
  • the first urethane acrylate and the second urethane acrylate include urethane polymer groups.
  • the urethane polymer group may be selected from at least one of the following groups: polyester urethane, polyether urethane, polycarbonate urethane or polypropylene amino Formate.
  • the selection of the above-mentioned urethane acrylate group can help to improve the interfacial bonding strength between the support layer and the bonding layer.
  • the total thickness of the supporting layer 11 accounts for 30%-80% of the total thickness of the optical glue. It can be understood that, when the support layer 11 is one layer, the total thickness of the support layer 11 is the thickness of one support layer 11; when the support layer 11 is two layers, the total thickness of the support layer 11 is two layers of support layers 11 The sum of the thicknesses; when the support layer 11 is three layers, the total thickness of the support layer 11 is the sum of the thicknesses of the three support layers 11. Wherein, the total thickness of the support layer 11 can be 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75% or 80% of the total thickness of the optical glue 10, for example.
  • the support layer 11 may also include a photoinitiator, by setting the photoinitiator to initiate the first urethane acrylate and the polymerization and curing of the second urethane acrylate.
  • the photoinitiator can be a conventional UV photoinitiator, for example, can include benzoin series, hydroxyketone series, aminoketone or bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide based on phosphine oxide, At least one of 2-hydroxy-2-methyl-1-phenylpropan-1-one or 1-hydroxycyclohexyl phenyl ketone 2-methyl-1-[4-] and the like.
  • the specific type of photoinitiator is not limited.
  • the adhesive layer 12 covers the surface of the support layer 11 , and in the formed OCA, the adhesive layer 12 is located at the outermost layer of the OCA.
  • OCA transparent cover plate, polarizer, touch screen, display panel and other film layers in the folding screen are bonded by OCA, and the adhesive layer 12 of OCA is used to contact and bond with each film layer. In order to realize the bonding function of OCA.
  • the adhesive layer 12 contains an acrylic adhesive.
  • the acrylic adhesive may be, for example, an acrylic adhesive, or may be an acrylic adhesive containing a hydroxyl group, or may be an acrylic adhesive and an acrylic adhesive containing a hydroxyl group.
  • acrylates containing hydroxyl groups may include, for example, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 4- At least one of hydroxycyclohexyl (meth)acrylate or 5-hydroxycyclohexyl (meth)acrylate.
  • the adhesive layer 12 may also include a copolymer, and the copolymer includes a vinyl copolymer, a silicone copolymer, an olefin copolymer, polyurethane acrylate (meth)acrylate or polybutylene diacrylate. At least one of di(meth)acrylates.
  • the adhesive layer 12 may further contain additives.
  • additives such as 2-ethylhexyl (meth)acrylate, isobornyl (meth)acrylate, n-butyl (meth)acrylate, tert-butyl (meth)acrylate, cyclopentyl At least one of base (meth)acrylate, cyclohexyl (meth)acrylate and the like.
  • the adhesive layer 12 may further contain additives, such as an initiator.
  • the initiator may be a conventional photopolymerization initiator or thermal polymerization initiator in the art.
  • the photopolymerization initiator may include benzoin, benzoin methyl ether, acetophenone, dimethylaminoacetophenone, benzophenone, p-phenylbenzophenone, 2-methylanthraquinone, 2- At least one of ethylanthraquinone, and 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide;
  • the thermal polymerization initiator may contain azo compounds, peroxide compounds, and redox compounds at least one of compounds and the like.
  • the raw materials for forming the adhesive layer include acrylate polymers, copolymers and initiators.
  • the adhesive layer 12 and the glass, polyester film, polyimide film and other film layers have a 180° peel strength at 25°C ⁇ 4N/cm, preferably ⁇ 8N/cm cm.
  • the present application also provides a preparation method of optical glue.
  • the preparation method of optical glue comprises the following steps: providing at least one support layer 11, forming bonding layer 12 respectively on both sides of any support layer 11; Wherein, the support layer contains The polyurethane polymer has a weight-average molecular weight of 2,000-60,000.
  • Fig. 4 is a schematic flow chart of the preparation method of optical glue according to an embodiment of the present application
  • Fig. 5 to Fig. 8 are schematic diagrams of the preparation process of optical glue, referring to Fig. 1 and Fig. 4-Fig.
  • the preparation method of optical adhesive comprises the following steps:
  • the surface of the first release film 21 is coated with acrylate glue, and after UV curing or thermal curing, an adhesive layer 12 is formed, wherein the first release film 21 can be a heavy-duty release film membrane;
  • the polyurethane polymer slurry is coated on the surface of the adhesive layer 11 obtained in step S11), and the support layer 11 is formed after UV curing or heat curing; wherein, the first polyurethane acrylate and After the second urethane acrylate and the photoinitiator are mixed, the urethane polymer slurry is formed; the selection of the first urethane acrylate, the second urethane acrylate and the photoinitiator can refer to the description of each embodiment of the optical adhesive in this application.
  • the surface of the second release film 22 is coated with acrylate glue, and another layer of adhesive layer 12 is formed after UV curing or heat curing, wherein the second release film 22 can be light Release film, the peeling force of the second release film 22 and the adhesive layer 12 is less than the peeling force of the first release film 21 and the adhesive layer 12;
  • first release film and the second release film play the role of the carrier, and the first release film and the second release film need to be torn off during the later use of the OCA, so
  • the selection of the above-mentioned first release film and second release film is only illustrative, as long as the release film can provide support and protection during preparation and use and is easy to tear off later, any release film can be used.
  • Fig. 9 is another embodiment of the preparation method of the optical adhesive of the present application, the preparation method utilizes the co-extrusion process to prepare the optical adhesive.
  • the preparation method of optical glue includes the following steps:
  • optical adhesive of the present application will be further described in detail below in combination with specific examples and comparative examples.
  • the present embodiment is a kind of OCA, and the structure of this OCA can refer to Fig. 1, and its preparation process is as follows:
  • acrylic glue preparation of acrylic glue: mix 42g of acrylic resin, 2g of monomer 4-hydroxybutyl acrylate, and 2g of additive (3-methacryloxypropyltrimethoxysilane) in proportion by weight, and put Put it into a high-speed shear dispersion mixing apparatus equipped with a vacuum device, mix at a rate of 200 rpm for 5 minutes under vacuum conditions, then mix at a rate of 2000 rpm for 1 min, and store in a can.
  • additive 3-methacryloxypropyltrimethoxysilane
  • preparation of the upper acrylic adhesive layer 12 apply acrylic glue on one side of the light-duty release film, then heat it at 80-150°C to cure, and at the same time cover the surface with a light-duty release film to obtain an acrylic adhesive layer 12.
  • the preparation of the lower acrylic adhesive layer 12 apply acrylic glue on one side of the heavy-duty release film, then heat it at 80-150°C to cure, and at the same time cover the surface with a light-duty release film to obtain another layer of acrylic adhesive Layer 12.
  • polyurethane polymer slurry preparation the first polyurethane acrylate with a weight average molecular weight of 10000 and the second polyurethane acrylate with a weight average molecular weight of 35000, photoinitiator are mixed in a ratio of 40g:10g:1g, put Put it into a high-speed shear dispersion mixing apparatus equipped with a vacuum device, mix at a rate of 200 rpm for 5 minutes under vacuum conditions, then mix at a rate of 2000 rpm for 1 min, and store in a can.
  • polyurethane acrylate layer preparation tear off the light-duty release film of the lower acrylic adhesive layer, coat the polyurethane acrylate slurry on the surface of the lower acrylic adhesive layer, and perform UV curing under a UV 365nm ⁇ 405nm wavelength light source, A urethane acrylate layer, that is, the supporting layer 11 is formed.
  • OCA finished product preparation tear off the light-duty release film of the upper acrylic adhesive layer, and attach the upper acrylic adhesive layer to the surface of the cured polyurethane acrylate layer to form the final OCA adhesive.
  • the OCA obtained in this example has a 180° peeling force of 8.5 N/cm to the interface of the transparent polyimide film.
  • the OCA obtained in this example has a storage modulus of 40KPa at 25°C and a recovery rate of 92%.
  • the OCA obtained in this example is used in a folding screen.
  • the bending radius is R2.5mm, it can be bent 200,000 times without OCA failure.
  • This embodiment is a kind of OCA, the preparation method of this embodiment OCA refers to embodiment 1, the difference between this embodiment OCA and embodiment 1 is that the first urethane acrylate with a weight average molecular weight of 10000 and the weight average molecular weight Be the second urethane acrylate of 35000, photoinitiator is mixed in the ratio of 40g:5g:1g, other are all identical with embodiment 1.
  • This embodiment is a kind of OCA, the preparation method of this embodiment OCA refers to embodiment 1, the difference between this embodiment OCA and embodiment 1 is that the first urethane acrylate with a weight average molecular weight of 10000 and the weight average molecular weight Be the second urethane acrylate of 35000, photoinitiator is mixed in the ratio of 35g:15g:1g, other are all identical with embodiment 1.
  • This embodiment is a kind of OCA, the preparation method of this embodiment OCA refers to Example 1, the difference between this embodiment OCA and Example 1 is that the first urethane acrylate with a weight average molecular weight of 15000 and the weight average molecular weight Be the second urethane acrylate of 45000, photoinitiator is mixed in the ratio of 40g:10g:1g, other are all identical with embodiment 1.
  • This embodiment is a kind of OCA, the preparation method of this embodiment OCA refers to embodiment 1, the difference between this embodiment OCA and embodiment 1 is that the first urethane acrylate with a weight average molecular weight of 5000 and the weight average molecular weight Be the second urethane acrylate of 25000, photoinitiator is mixed in the ratio of 40g:10g:1g, other are all identical with embodiment 1.
  • This embodiment is a kind of OCA, the preparation method of this embodiment OCA refers to embodiment 1, the difference between this embodiment OCA and embodiment 1 is that the first urethane acrylate with a weight average molecular weight of 10000, photoinitiator Mix by the ratio of 50g:1g, others are all identical with embodiment 1.
  • This embodiment is a kind of OCA, the preparation method of this embodiment OCA refers to embodiment 1, the difference between this embodiment OCA and embodiment 1 is that the first urethane acrylate with a weight average molecular weight of 35000, photoinitiator Mix by the ratio of 50g:1g, others are all identical with embodiment 1.
  • This comparative example is an OCA with only one acrylic tie layer.
  • the composition of the acrylic adhesive layer was the same as that of the acrylic adhesive layer in Example 1.
  • This comparative example is a kind of OCA, and its preparation process is as follows:
  • acrylic glue preparation of acrylic glue: mix 42g of acrylic resin, 2g of monomer 4-hydroxybutyl acrylate, and 2g of additive (3-methacryloxypropyltrimethoxysilane) in proportion by weight, and put Put it into a high-speed shear dispersion mixing apparatus equipped with a vacuum device, mix at a rate of 200 rpm for 5 minutes under vacuum conditions, then mix at a rate of 2000 rpm for 1 min, and store in a can.
  • additive 3-methacryloxypropyltrimethoxysilane
  • preparation of the upper acrylic adhesive layer coating acrylic glue on one side of the heavy-duty release film, then heating at 80-150°C for curing, and simultaneously covering the surface with a light-duty release film to obtain an acrylic adhesive layer.
  • preparation of the lower acrylic adhesive layer apply acrylic glue on one side of the light-duty release film, and then heat it at 80-150°C for curing, and at the same time cover the surface with a light-duty release film to obtain another acrylic adhesive layer .
  • urethane acrylate slurry preparation of urethane acrylate slurry: the weight average molecular weight is 1000 urethane acrylate, photoinitiator are mixed in the ratio of 50g:1g, put into the high-speed shear dispersion mixing instrument with vacuum device, in vacuum Under the conditions, mix at a rate of 200 rpm for 5 minutes, then mix at a rate of 2000 rpm for 1 min, and store in jars.
  • polyurethane acrylate layer preparation tear off the light-duty release film of the lower acrylic adhesive layer, coat the polyurethane acrylate slurry on the surface of the lower acrylic adhesive layer, and perform UV curing under a UV 365nm ⁇ 405nm wavelength light source, A urethane acrylate layer is formed.
  • OCA finished product preparation tear off the light-duty release film of the upper acrylic adhesive layer, and attach the upper acrylic adhesive layer to the surface of the cured polyurethane acrylate layer to form the final OCA adhesive.
  • This comparative example is a kind of OCA, and its preparation process is as follows:
  • acrylic glue preparation of acrylic glue: mix 42g of acrylic resin, 2g of monomer 4-hydroxybutyl acrylate, and 2g of additive (3-methacryloxypropyltrimethoxysilane) in proportion by weight, and put Put it into a high-speed shear dispersion mixing apparatus equipped with a vacuum device, mix at a rate of 200 rpm for 5 minutes under vacuum conditions, then mix at a rate of 2000 rpm for 1 min, and store in a can.
  • additive 3-methacryloxypropyltrimethoxysilane
  • preparation of the upper acrylic adhesive layer coating acrylic glue on one side of the heavy-duty release film, then heating at 80-150°C for curing, and simultaneously covering the surface with a light-duty release film to obtain an acrylic adhesive layer.
  • preparation of the lower acrylic adhesive layer apply acrylic glue on one side of the light-duty release film, and then heat it at 80-150°C for curing, and at the same time cover the surface with a light-duty release film to obtain another acrylic adhesive layer .
  • polyurethane acrylate slurry preparation the weight average molecular weight is 80000 polyurethane acrylate, photoinitiator are mixed in the ratio of 50g:1g, put into the high-speed shear dispersion mixing instrument with vacuum device, in vacuum Under the conditions, mix at a rate of 200 rpm for 5 minutes, then mix at a rate of 2000 rpm for 1 min, and store in jars.
  • polyurethane acrylate layer preparation tear off the light-duty release film of the lower acrylic adhesive layer, coat the polyurethane acrylate slurry on the surface of the lower acrylic adhesive layer, and perform UV curing under a UV 365nm ⁇ 405nm wavelength light source, A urethane acrylate layer is formed.
  • OCA finished product preparation tear off the light-duty release film of the upper acrylic adhesive layer, and attach the upper acrylic adhesive layer to the surface of the cured polyurethane acrylate layer to form the final OCA adhesive.
  • Haze refer to the light transmittance test, and use the spectrophotometer CM-3600A to obtain the haze value.
  • Yellowing index b* refer to the light transmittance test, and use the spectrophotometer CM-3600A to obtain the yellowing index value.
  • the OCA provided in the embodiment of the present application can have the characteristics of high flexibility, high recovery, and high adhesion, and has more excellent bending resistance.
  • the urethane acrylate in the optical glue of the present application has high light transmission, low haze and is not easy to yellow, and has excellent optical properties on the basis of good mechanical properties.
  • folding screens are less resistant to external stress than straight phones. Screen failure is prone to occur when subjected to external stress such as falling balls and pen falls.
  • the OCA provided in the embodiment of the present application is used as the main buffer material inside the screen, which needs to withstand a certain buffer capacity to improve the tolerance of the screen.

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Abstract

本申请提供了一种光学胶及其制备方法、显示屏与终端设备。该光学胶包括至少一层支撑层，任一支撑层的两侧表面均设有粘结层，其中，支撑层中含有聚氨酯类聚合物，聚氨酯类聚合物的重均分子量为2000～60000。该光学胶具有经反复弯折，本体不易破坏、不易从粘结界面脱落、不易使折叠屏的刚性膜材发生断裂的优点。

Description

光学胶及其制备方法、显示屏与终端设备 技术领域
本申请涉及柔性屏领域，具体涉及一种光学胶及其制备方法、显示屏与终端设备。
背景技术
随着显示技术的日趋发展，柔性显示装置的应用越来越广泛，尤其以折叠屏手机成为当前主要发展方向。折叠屏主要由柔性有机发光二极管(organic light-emitting diode，OLED)显示屏，以及铰链结构实现组装。其中，OLED显示屏主要是由透明盖板、偏光片、触摸屏、显示面板等组成的叠层模组，各膜层之间通过光学胶(optical clear adhesive，OCA)贴合粘接。整个显示屏中，OCA通过其自身的粘结性实现对各膜层的粘接功能，同时又通过OCA的柔性及可回复性实现显示屏的耐弯折特性，因此，OCA已成为折叠屏中的关键材料。
传统的OCA，一般为单层的丙烯酸酯粘结胶，在折叠屏反复弯折后易于形成错位形变，使得OCA经常出现界面脱胶、本体破坏出现气泡等失效。一些高模量高粘结力OCA虽然在胶本体或界面不容易发生破坏，但是存在因柔性不足而产生高应力容易造成折叠屏中的其他膜材发生断裂的问题。因此，目前还缺少一种经反复弯折，本体不易破坏、且不易从粘结界面脱胶、不易使折叠屏的其他膜材发生断裂的光学胶。
发明内容
本申请提供了一种光学胶及其制备方法、显示屏与终端设备，以获得一种经反复弯折，本体不易破坏、不易从粘结界面脱落、不易使折叠屏的刚性膜材发生断裂的光学胶。
第一方面，本申请提供一种光学胶，该光学胶包括至少一层支撑层，任一支撑层的两侧表面均设有粘结层，其中，支撑层中含有聚氨酯类聚合物，聚氨酯类聚合物的重均分子量为2000～60000。
本申请提供的光学胶，包括至少一层支撑层，支撑层以重均分子量为2000～60000的聚氨酯类聚合物为主体材料，可实现高柔性和高回复性，可有效防止OCA以及折叠屏的其他刚性膜材弯折过程中发生断裂，同时，使该OCA本体不易发生破坏。另外，支撑层的两相对设置的表面均设置粘结层，可实现与折叠屏其他膜材的有效粘结。由此，本申请提供的OCA，可兼具高柔性、高回复性、高粘接性的特点，同时具有更优异的耐弯折性能。另外，本申请光学胶中的聚氨酯丙烯酸酯-丙烯酸酯，透光性高、雾度低且不易黄变，在具有较好机械性能的基础上，还具有优异的光学性能。
在本申请一种可能的实现方式中，聚氨酯类聚合物包括第一聚氨酯丙烯酸酯，第一聚氨酯丙烯酸酯的重均分子量为2000～20000，25℃下的储能模量值E 25为5～80KPa。该性能的聚氨酯丙烯酸酯，柔性自由度高，在受到外应力时，发生自由形变，应力得到自由释放；当外应力撤掉时，形变反方向回复。由此，可利于提高光学胶的弹性形变能力，提高光学胶的可回复性。
在本申请一种可能的实现方式中，第一类聚氨酯丙烯酸酯在25℃下的储能模量值E 25>3×10 4Pa，60℃下的储能模量值E 60>2×10 4Pa，-20℃下的储能模量值E -20<2×10 5Pa， -40℃下的储能模量值E -40<1×10 6Pa。以利于提高光学胶在不同温度应用场景下的弹性形变能力，提高光学胶在不同温度应用场景下的可回复性。
在本申请一种可能的实现方式中，第一聚氨酯丙烯酸酯含有聚氨酯丙烯酸酯键和氢键。氨基甲酸酯丙烯酸酯键和氢键的存在，可有助于聚氨酯丙烯酸酯形成螺旋网状结构。该结构的聚氨酯丙烯酸酯，柔性自由度高，在受到外应力时，发生自由形变，应力得到自由释放；当外应力撤掉时，形变反方向回复。该过程中，主链不容易发生塑性变形，从而可提供高柔性和高回复性。
在本申请一种可能的实现方式中，第一聚氨酯丙烯酸酯包括氨基甲酸酯聚合物。
其中，作为示例性说明，氨基甲酸酯聚合物包括聚酯氨基甲酸酯、聚醚氨基甲酸酯、聚碳酸酯氨基甲酸酯或聚丙烯氨基甲酸酯中的至少一种。
在本申请一种可能的实现方式中，聚氨酯类聚合物包括第二聚氨酯丙烯酸酯，第二聚氨酯丙烯酸酯的重均分子量为23000～60000，25℃下的储能模量值E 25为100～500KPa。该性能的第二聚氨酯丙烯酸酯可与粘结层产生较强的粘结力，从而可利于提高支撑层与粘结层的粘结力，有效避免光学胶内部出现层间剥离。
在本申请一种可能的实现方式中，第二聚氨酯丙烯酸酯在25℃下的储能模量值E 25>12×10 4Pa，60℃下的储能模量值E 60>5×10 4Pa，-20℃下的储能模量值E -20<5×10 5Pa，-40℃下的储能模量值E -40<3×10 6Pa。由此，可利于提高光学胶在不同温度应用场景下的弹性形变能力，另外，可提高光学胶在不同温度应用场景下的可回复性。
在本申请一种可能的实现方式中，第二聚氨酯丙烯酸酯的断裂伸长率≥200％，以利于提高光学胶的应变性能。
在本申请一种可能的实现方式中，第一聚氨酯丙烯酸酯与第二聚氨酯丙烯酸酯的重量比为9:1～2:1，优选7:1～3:1，进一步优选5:1～3:1。
在本申请一种可能的实现方式中，第二聚氨酯丙烯酸酯包括氨基甲酸酯聚合物。其中，作为示例性说明，氨基甲酸酯聚合物包括聚酯氨基甲酸酯、聚醚氨基甲酸酯、聚碳酸酯氨基甲酸酯或聚丙烯氨基甲酸酯中的至少一种。
在本申请一种可能的实现方式中，支撑层的总厚度占光学胶总厚度的30％～80％。这样，可使光学胶具有高柔性和高回复性的同时，具有较高的粘结性能。
在本申请一种可能的实现方式中，支撑层的回复率>85％，以利于提高光学胶的可回复性能。
在本申请一种可能的实现方式中，支撑层的可见光透光率>90％，雾度≤2％，黄变指数≤3。利于提高光学胶的光学性能。
在本申请一种可能的实现方式中，粘结层中含有丙烯酸酯类粘结剂。丙烯酸酯类粘结层与聚氨酯丙烯酸酯之间具有较好的粘结性能，以利于提高支撑层和粘结层之间的粘结强度。
在本申请一种可能的实现方式中，丙烯酸酯类粘结剂包括丙烯酸酯和/或含有羟基的(甲基)丙烯酸酯。在本申请一种可能的具体实现方式中，含有羟基的(甲基)丙烯酸酯包括2-羟乙基(甲基)丙烯酸酯、2-羟丙基(甲基)丙烯酸酯、4-羟丁基(甲基)丙烯酸酯、4-羟环己基(甲基)丙烯酸酯或5-羟环辛基(甲基)丙烯酸酯中至少一种。
在本申请一种可能的实现方式中，粘结层中还包括以下共聚物中的至少一种，共聚物包含乙烯基共聚物、有机硅共聚物、烯烃共聚物、聚氨酯丙烯酸酯(甲基)丙烯酸酯或聚丁 二烯二(甲基)丙烯酸酯，以进一步提高粘结层的粘结性能。
第二方面，本申请还提供一种光学胶的制备方法，该制备方法包括：提供至少一支撑层，在任一支撑层的两侧分别形成粘结层；其中，支撑层中含有聚氨酯类聚合物，聚氨酯类聚合物的重均分子量为2000～60000。
本申请提供的光学胶的制备方法，利用该制备方法得到的光学胶，包括至少一层支撑层，该支撑层以重均分子量为2000～60000的聚氨酯类聚合物为主体材料，可实现高柔性和高回复性，可有效防止OCA以及折叠屏的其他刚性膜材弯折过程中发生断裂，同时，使该OCA本体不易发生破坏。另外，支撑层的两相对设置的表面均设置粘结层，可实现与折叠屏其他摩擦的有效粘结。由此，本申请提供的OCA，可兼具高柔性、高回复性、高粘接性的特点，同时具有更优异的耐弯折性能。另外，本申请光学胶中的聚氨酯丙烯酸酯，透光性高、雾度低且不易黄变，在具有较好机械性能的基础上，还具有优异的光学性能。
在本申请一种可能的实现方式中，将第一聚氨酯丙烯酸酯和第二聚氨酯丙烯酸酯以及光引发剂混合后，形成聚氨酯类聚合物浆料。
在本申请一种可能的实现方式中，在任一支撑层的两侧分别形成粘结层，包括：
在第一离型膜的表面涂覆胶液，固化后形成一层粘结层；
在粘结层的表面涂覆聚氨酯丙烯酸酯浆料，固化后形成支撑层；
在第二离型膜的表面涂覆胶液，固化后形成另一层粘结层；
将第二离型膜表面的粘结层贴合在支撑层的表面。
其中，在第一离型膜的表面形成依次形成粘结层和支撑层后，还可继续重复形成粘结层和支撑层的步骤，依次形成交替设置的多层粘结层和多层支撑层，例如两层、三层、四层或更多层等。
在本申请另一种可能的实现方式中，在任一支撑层的两侧分别形成粘结层，包括：利用共挤工艺，同时共挤形成依次叠层设置的粘结层和支撑层。其中，共挤过程中，可根据最终形成的OCA的结构，对粘结层和支撑层的挤出模头进行设计。其中，共挤时，最外层要保证共挤出粘结层。
第三方面，本申请还提供一种显示屏，该显示屏包括依次设置的透明盖板、偏光片、触摸屏和显示面板，其中，透明盖板与偏光片之间、偏光片与触摸屏之间、触摸屏与显示面板之间设有本申请第一方面的光学胶。
本申请的显示屏，由于包括本申请第一方面的光学胶，因此，在本申请光学胶具备高柔性、高回复性、高粘接性的基础上，本申请的显示屏具有较高的使用寿命。
在本申请一种可能的实现方式中，显示屏为柔性显示屏。其中，该显示屏可为柔性折叠屏。
第四方面，本申请提供一种终端设备，包括本申请第三方面的显示屏。
本申请的终端设备，由于包括本申请第三方面的显示屏，由此，本申请的终端设备也同样具有使用寿命长的特点。
附图说明
图1为本申请一种实施例的光学胶的结构示意图；
图2为本申请另一种实施例的光学胶的结构示意图；
图3为本申请另一种实施例的光学胶的结构示意图；
图4为本申请一种实施例的光学胶的制备方法流程示意图；
图5为本申请一种实施例中制备粘结层的结构示意图；
图6为本申请一种实施例中制备支撑层的结构示意图；
图7为本申请一种实施例中制备另一层粘结层的结构示意图；
图8为本申请一种实施例中制备光学胶的结构示意图；
图9为本申请另一种实施例的光学胶的制备方法流程示意图。
附图标记：10-光学胶；11-支撑层；12-粘结层；21-第一离型膜；22-第二离型膜。
具体实施方式
为了使本申请的目的、技术方案和优点更加清楚，下面将结合附图对本申请作进一步地详细描述。
随着显示技术的日趋发展，柔性显示装置的应用越来越广泛，尤其以折叠屏手机成为当前主要发展方向。折叠屏主要由柔性有机发光二极管(organic light-emitting diode，OLED)显示屏，以及铰链结构实现组装。其中，OLED显示屏主要是由透明盖板、偏光片、触摸屏、显示面板等组成的叠层模组，各膜层之间通过光学胶(optical clear adhesive，OCA)贴合粘接。整个显示屏中，OCA通过其自身的粘结性实现对各膜层的粘接功能，同时又通过OCA的柔性及可回复性实现显示屏的耐弯折特性，因此，OCA已成为折叠屏中的关键材料。
折叠屏要实现10～20万次的耐弯折特性，要求OCA需具备如下特性：(1)具备优异的柔性形变能力，折叠屏中的刚性膜材(透明盖板、偏光片、触摸屏等)通过OCA的柔性形变吸收较大错位，实现弯折；(2)具备优异的形变回复能力，在反复发生大形变后具备回复能力，本身不发生塑性、褶皱等失效；(3)OCA对粘接界面(例如透明盖板、偏光片等表面)需要具备优异的粘接性能，在经过反复错位形变后，对界面不出现脱胶等失效。折叠屏的常见失效问题是OCA在经历弯折(常温、低温或高温不同场景下)后，出现OCA界面剥离、气泡失效问题。现有OCA在柔性、可回复性及粘接性能这三大特性上通常存在矛盾，无法同时实现。当OCA模量低、柔性高时，回复性及粘接力不足，容易发生塑性变形而造成OCA本体破坏；当OCA模量高、回复性高时，其柔性往往不足，应力偏大。因此，目前还缺少一种经反复弯折，本体不易破坏、且不易从粘结界面脱胶、不易使折叠屏的其他膜材发生断裂的光学胶。
为了解决上述技术问题，本申请实施例提供一种光学胶。以下实施例中所使用的术语只是为了描述特定实施例的目的，而并非旨在作为对本申请的限制。如在本申请的说明书和所附权利要求书中所使用的那样，单数表达形式“一个”、“一种”、“”、“上述”、“该”和“这一”旨在也包括例如“一个或多个”这种表达形式，除非其上下文中明确地有相反指示。
在本说明书中描述的参考“一个实施例”或“一些实施例”等意味着在本申请的一个或多个实施例中包括结合该实施例描述的特定特征、结构或特点。由此，在本说明书中的不同之处出现的语句“在一个实施例中”、“在一些实施例中”、“在其他一些实施例中”、“在另外一些实施例中”等不是必然都参考相同的实施例，而是意味着“一个或多个但不是所有的实施例”，除非是以其他方式另外特别强调。术语“包括”、“包含”、“具有”及它们的变形都意味着“包括但不限于”，除非是以其他方式另外特别强调。
图1为本申请一种实施例的光学胶的结构示意图。如图1所示，在本申请一种实施例中，光学胶10可包括至少一层支撑层11，任一支撑层11的两侧表面均设有粘结层12。
其中，如图1所示，在本申请一种实施例中，支撑层11的层数可为一层，该支撑层11包括两相对设置的表面，在该支撑层11两相对设置的表面均设有粘结层12。
图2为本申请另一种实施例的光学胶的结构示意图。如图2所示，在本申请一种实施例中，该光学胶10可包括两层支撑层11，任一层支撑层11的两相对设置的表面均设有粘结层12，相邻的两支撑层11之间可通过一层粘结层12粘结。
图3为本申请另一种实施例的光学胶的结构示意图。如图3所示，在本申请一种实施例中，光学胶10可包括三层支撑层11，任一支撑层11的两相对设置的表面均设有粘结层12，其中，相邻的两支撑层11之间可通过一层粘结层12粘结。
可以理解的是，上述光学胶的结构仅为示例性说明，本申请实施例的光学胶10中的支撑层11的数量除可设置一层、两层或三层外，还可设置四层、五层或更多，在此不做具体的限定。
下面分别对支撑层和粘结层做详细的解释说明。
支撑层11
一并参照图1-图3，在本申请一种实施例中，支撑层11中含有聚氨酯类聚合物，聚氨酯类聚合物的重均分子量为2000～60000。其中，作为示例性说明，形成支撑层11的聚氨酯类聚合物的重均分子量例如可为：2000、4000、6000、8000、10000、12000、14000、16000、18000、20000。以上重均分子量仅为示例性说明，并非对聚氨酯类聚合物的具体限定。
其中，在本申请一种实施例中，该聚氨酯类聚合物包括第一聚氨酯丙烯酸酯，第一聚氨酯丙烯酸酯的重均分子量为2000～20000，25℃下的储能模量值E 25为5～80KPa。在本申请一种实施例中，第一类聚氨酯丙烯酸酯在25℃下的储能模量值E 25>3×10 4Pa，60℃下的储能模量值E 60>2×10 4Pa，-20℃下的储能模量值E -20<2×10 5Pa，-40℃下的储能模量值E -40<1×10 6Pa。储能模量又称为弹性模量，是指材料在发生形变时，由于弹性(可逆)形变而储存能量的大小，反映材料弹性大小。选用满足上述条件的聚氨酯丙烯酸酯形成的支撑层，可有效提高光学胶的弹性形变能力，提高光学胶的可回复性，同时，可有效扩大光学胶的应用范围，使其不受环境温度的影响而失效。
在本申请一种实施例中，第一聚氨酯丙烯酸酯含有聚氨酯丙烯酸酯键和氢键。聚氨酯丙烯酸酯键和氢键的存在，可有助于聚氨酯丙烯酸酯形成螺旋网状结构。该结构的聚氨酯丙烯酸酯，柔性自由度高，在受到外应力时，发生自由形变，应力得到自由释放；当外应力撤掉时，形变反方向回复。该过程中，主链不容易发生塑性变形，从而可提供高柔性和高回复性。
在本申请一种实施例中，支撑层中除包括第一聚氨酯丙烯酸酯外，还可包括第二聚氨酯丙烯酸酯，该第二聚氨酯丙烯酸酯的重均分子量为23000～60000，25℃下的储能模量值E 25为100～500KPa。进一步，在本申请另一种实施例中，第二聚氨酯丙烯酸酯在25℃下的储能模量值E 25>12×10 4Pa，60℃下的储能模量值E 60>5×10 4Pa，-20℃下的储能模量值E -20<5×10 5Pa，-40℃下的储能模量值E -40<3×10 6Pa。第二聚氨酯丙烯酸酯的断裂伸长率≥200％。
在本申请一种实施例中，第一聚氨酯丙烯酸酯与第二聚氨酯丙烯酸酯的重量比为 9:1～2:1，优选7:1～3:1，进一步优选5:1～3:1。通过选用上述重量比的第一聚氨酯丙烯酸酯与第二聚氨酯丙烯酸酯，既可提高光学胶的柔韧性、弹性变形能力和可回复性，还可以提高光学胶内部的粘结强度。其中，第一聚氨酯丙烯酸酯与第二聚氨酯丙烯酸酯的重量比定型但非限制性地为：9:1、8:1、7:1、6:1、5:1、4:1、3:1、2:1。
利用第一聚氨酯丙烯酸酯与第二聚氨酯丙烯酸酯形成的支撑层，可具有较高的柔韧性、较强的弹性形变能力和较强的可回复性；此外，还可使所得支撑层具有较高的透光率、较低的雾度以及较小的黄变指数。其中，支撑层的回复率可>85％，优选>88％，进一步优选>90％；支撑层的可见光透光率>90％，优选>92％，进一步优选>93％。支撑层的雾度≤2％，黄变指数≤3。
其中，支撑层11回复率的测试过程如下：25℃时，施加400％应变保持10min，然后撤销应力自然回复10min，10min后测试支撑层的剩余应变值，计算公式如下：
Figure PCTCN2021103185-appb-000001
在本申请一种实施例中，第一聚氨酯丙烯酸酯和第二聚氨酯丙烯酸酯包括氨基甲酸酯聚合物基团。作为示例性说明，氨基甲酸酯聚合物基团可选自以下基团中的至少一种：聚酯氨基甲酸酯、聚醚氨基甲酸酯、聚碳酸酯氨基甲酸酯或聚丙烯氨基甲酸酯。选用上述聚氨酯丙烯酸酯基团，可有利于提高支撑层与粘结层之间的界面粘结强度。
在本申请一种实施例中，支撑层11的总厚度占光学胶总厚度的30％～80％。可以理解的是，当支撑层11为一层时，支撑层11的总厚度为一层支撑层11的厚度；当支撑层11为两层时，支撑层11的总厚度为两层支撑层11的厚度之和；当支撑层11为三层时，支撑层11的总厚度为三层支撑层11的厚度之和。其中，支撑层11的总厚度例如可为光学胶10总厚度的30％、35％、40％、45％、50％、55％、60％、65％、70％、75％或80％。
在本申请一种实施例中，支撑层11中除了含有第一聚氨酯丙烯酸酯和第二聚氨酯丙烯酸酯外，还可包括光引发剂，通过设置光引发剂，以用于引发第一聚氨酯丙烯酸酯和第二聚氨酯丙烯酸酯的聚合以及固化。其中，光引发剂可为常规UV光引发剂，例如可以包含安息香系、羟基酮系、氨基酮或基于氧化膦的双(2,4,6-三甲基苯甲酰基)苯基氧化膦、2-羟基-2-甲基-1-苯基丙-1-酮或1-羟基环己基苯基酮2-甲基-1-[4-]等中的至少一种。在此，不对光引发剂的具体种类做出限定。
粘结层12
继续参照图1-图3，在本申请一种实施例中，粘结层12覆盖在支撑层11的表面，在形成的OCA中，粘结层12位于OCA的最外层。当将OCA用于折叠屏中时，折叠屏中的透明盖板、偏光片、触摸屏、显示面板等各膜层通过OCA粘结，OCA的粘结层12用于与各个膜层接触粘结，以实现OCA的粘结功能。
在本申请一种实施例中，粘结层12中含有丙烯酸酯类粘结剂。其中，丙烯酸酯类粘结剂例如可为丙烯酸酯粘结剂，或可为含有羟基的丙烯酸酯的粘结剂，又或者可为丙烯酸酯粘结剂和含有羟基的丙烯酸酯粘结剂。
作为举例说明，含有羟基的丙烯酸酯例如可包括2-羟乙基(甲基)丙烯酸酯、2-羟丙基(甲基)丙烯酸酯、4-羟丁基(甲基)丙烯酸酯、4-羟环己基(甲基)丙烯酸酯或5-羟环辛基(甲基)丙烯酸酯中至少一种。
在本申请一种实施例中，粘结层12中还可包括共聚物，共聚物包含乙烯基共聚物、有机硅共聚物、烯烃共聚物、聚氨酯丙烯酸酯(甲基)丙烯酸酯或聚丁二烯二(甲基)丙烯酸酯中至少一种。
在本申请一种实施例中，粘结层12中还可含有添加剂。其中，添加剂例如可为2-乙基己基(甲基)丙烯酸酯、异冰片基(甲基)丙烯酸酯、正丁基(甲基)丙烯酸酯、叔丁基(甲基)丙烯酸酯、环戊基(甲基)丙烯酸酯、环己基(甲基)丙烯酸酯等中的至少一种。
在本申请一种实施例中，粘结层12中还可含有添加剂，例如引发剂。其中，引发剂可以是本领域常规光聚合引发剂或热聚合引发剂。作为示例性说明，光聚合引发剂可以包含安息香、安息香甲醚、苯乙酮、二甲氨基苯乙酮、二苯甲酮、对苯基二苯甲酮、2-甲基蒽醌、2-乙基蒽醌、以及2,4,6-三甲基苯甲酰基-二苯基-膦氧化物等中的至少一种；热聚合引发剂可以包含偶氮化合物、过氧化物化合物以及氧化还原化合物等中的至少一种。在本申请的一种实施例中，形成粘结层的组成原料中包括丙烯酸酯类聚合物、共聚物和引发剂。
在本申请的一种实施例中，该粘结层12与玻璃、聚酯膜、聚酰亚胺膜等膜层，在25℃下，180°的剥离强度≥4N/cm，优选≥8N/cm。
基于同样的技术构思，本申请还提供一种光学胶的制备方法。参照图1，在本申请一种实施例中，光学胶的制备方法包括以下步骤：提供至少一支撑层11，在任一支撑层11的两侧分别形成粘结层12；其中，支撑层中含有聚氨酯类聚合物，聚氨酯类聚合物的重均分子量为2000～60000。
图4为本申请一种实施例的光学胶的制备方法流程示意图，图5至图8为光学胶的制备过程结构示意图，一并参照图1以及图4-图8，在本申请的一种实施例中，光学胶的制备方法包括以下步骤：
S11)、如图5所示，在第一离型膜21的表面涂覆丙烯酸酯胶夜，UV固化或热固化后形成粘结层12，其中，第一离型膜21可为重型离型膜；
S12)、如图6所示，在步骤S11)所得粘结层11的表面涂覆聚氨酯类聚合物浆料，UV固化或热固化后形成支撑层11；其中，可将第一聚氨酯丙烯酸酯和第二聚氨酯丙烯酸酯以及光引发剂混合后，形成聚氨酯类聚合物浆料；第一聚氨酯丙烯酸酯和第二聚氨酯丙烯酸酯以及光引发剂的选择可参照本申请光学胶各实施例部分的描述。
S13)、如图7所示，在第二离型膜22的表面涂覆丙烯酸酯胶，UV固化或热固化后形成另一层粘结层12，其中，第二离型膜22可为轻型离型膜，第二离型膜22与粘结层12的剥离力小于第一离型膜21与粘结层12的剥离力；
S14)、如图8所示，将涂覆有粘结层12的第二离型膜22贴合在支撑层11的表面，压合后形成光学胶。
其中，可以理解的是，上述第一离型膜和第二离型膜起到承载体的作用，在OCA的后期使用过程中需要将第一离型膜和第二离型膜撕除，因此，上述第一离型膜和第二离型膜的选择仅为示例性说明，只要在制备和使用过程中能够起到支撑保护且便于后期撕除的离型膜均可使用。
图9为本申请另一种实施例的光学胶的制备方法，该制备方法利用共挤工艺制备光学胶。如图9所示，在本申请一种实施例中，光学胶的制备方法包括以下步骤：
S21)、分别配置可UV固化或热固化的丙烯酸酯胶液和聚氨酯丙烯酸酯浆料；
S22)、采用三辊共挤工艺将丙烯酸酯胶液和聚氨酯丙烯酸酯挤出，涂布在第一离型膜 的表面，经UV固化或热固化后，形成光学胶。其中，可在光学胶的远离第一离型膜的表面覆盖第二离型膜，以保护光学胶不被污染。
下面将结合具体实施例和对比例对本申请的光学胶做进一步详细说明。
实施例1
本实施例为一种OCA，该OCA的结构可参照图1，其制备过程如下：
S101)、丙烯酸胶液制备：按重量配比将丙烯酸树脂42g、单体丙烯酸4-羟基丁酯2g、添加剂(3-甲基丙烯酰氧基丙基三甲氧基硅烷)2g组分混合，放入带有真空装置的高速率剪切分散混合仪器中，在真空条件下先以200转/每分钟速率混合5min，再以2000转/每分钟速率混合1min，罐装保存。
S102)、上层丙烯酸粘结层12制备：在轻型离型膜的一侧表面涂布丙烯酸胶液，然后加热80～150℃进行固化，同时表面覆轻型离型膜，得到一层丙烯酸粘结层12。
S103)、下层丙烯酸粘结层12制备：在重型离型膜的一侧表面涂布丙烯酸胶液，然后加热80～150℃进行固化，同时表面覆轻型离型膜，得到另外一层丙烯酸粘结层12。
S104)、聚氨酯类聚合物浆料制备：将重均分子量为10000的第一聚氨酯丙烯酸酯和重均分子量为35000的第二聚氨酯丙烯酸酯、光引发剂按40g:10g:1g的比例混合，放入带有真空装置的高速率剪切分散混合仪器中，在真空条件下先以200转/每分钟速率混合5min，再以2000转/每分钟速率混合1min，罐装保存。
S105)、聚氨酯丙烯酸酯层制备：撕除下层丙烯酸粘结层的轻型离型膜，将聚氨酯丙烯酸酯浆料涂布在下层丙烯酸粘结层的表面，UV 365nm～405nm波长光源下进行UV固化，形成聚氨酯丙烯酸酯层，即支撑层11。
S106)、OCA成品制备：撕除上层丙烯酸粘结层的轻型离型膜，将上层丙烯酸粘结层贴合在已固化的聚氨酯丙烯酸酯层表面，形成最终的OCA胶。
该实施例中得到的OCA，对透明聚酰亚胺膜界面的180°剥离力达到8.5N/cm。
该实施例中所得的OCA，25℃下的储能模量达40KPa，回复率达92％。
该实施例中所得的OCA，用于折叠屏中，弯折半径为R2.5mm时，弯折20万次，无OCA不良。
实施例2
本实施例为一种OCA，该实施例OCA的制备方法参照实施例1，该实施例OCA与实施例1的不同之处在于，将重均分子量为10000的第一聚氨酯丙烯酸酯和重均分子量为35000的第二聚氨酯丙烯酸酯、光引发剂按40g:5g:1g的比例混合，其他均与实施例1相同。
实施例3
本实施例为一种OCA，该实施例OCA的制备方法参照实施例1，该实施例OCA与实施例1的不同之处在于，将重均分子量为10000的第一聚氨酯丙烯酸酯和重均分子量为35000的第二聚氨酯丙烯酸酯、光引发剂按35g:15g:1g的比例混合，其他均与实施例1相同。
实施例4
本实施例为一种OCA，该实施例OCA的制备方法参照实施例1，该实施例OCA与实施例1的不同之处在于，将重均分子量为15000的第一聚氨酯丙烯酸酯和重均分子量为45000的第二聚氨酯丙烯酸酯、光引发剂按40g:10g:1g的比例混合，其他均与实施例1相同。
实施例5
本实施例为一种OCA，该实施例OCA的制备方法参照实施例1，该实施例OCA与实施例1的不同之处在于，将重均分子量为5000的第一聚氨酯丙烯酸酯和重均分子量为25000的第二聚氨酯丙烯酸酯、光引发剂按40g:10g:1g的比例混合，其他均与实施例1相同。
实施例6
本实施例为一种OCA，该实施例OCA的制备方法参照实施例1，该实施例OCA与实施例1的不同之处在于，将重均分子量为10000的第一聚氨酯丙烯酸酯、光引发剂按50g:1g的比例混合，其他均与实施例1相同。
实施例7
本实施例为一种OCA，该实施例OCA的制备方法参照实施例1，该实施例OCA与实施例1的不同之处在于，将重均分子量为35000的第一聚氨酯丙烯酸酯、光引发剂按50g:1g的比例混合，其他均与实施例1相同。
对比例1
该对比例为一种OCA，其仅为一层丙烯酸粘结层。该丙烯酸粘结层的成分与实施例1中的丙烯酸粘结层的成分相同。
对比例2
该对比例为一种OCA，其制备过程如下：
S101)、丙烯酸胶液制备：按重量配比将丙烯酸树脂42g、单体丙烯酸4-羟基丁酯2g、添加剂(3-甲基丙烯酰氧基丙基三甲氧基硅烷)2g组分混合，放入带有真空装置的高速率剪切分散混合仪器中，在真空条件下先以200转/每分钟速率混合5min，再以2000转/每分钟速率混合1min，罐装保存。
S102)、上层丙烯酸粘结层制备：在重型离型膜的一侧表面涂布丙烯酸胶液，然后加热80～150℃进行固化，同时表面覆轻型离型膜，得到一层丙烯酸粘结层。
S103)、下层丙烯酸粘结层制备：在轻型离型膜的一侧表面涂布丙烯酸胶液，然后加热80～150℃进行固化，同时表面覆轻型离型膜，得到另外一层丙烯酸粘结层。
S104)、聚氨酯丙烯酸酯浆料制备：将重均分子量为1000的聚氨酯丙烯酸酯、光引发剂按50g:1g的比例混合，放入带有真空装置的高速率剪切分散混合仪器中，在真空条件下先以200转/每分钟速率混合5min，再以2000转/每分钟速率混合1min，罐装保存。
S105)、聚氨酯丙烯酸酯层制备：撕除下层丙烯酸粘结层的轻型离型膜，将聚氨酯丙烯酸酯浆料涂布在下层丙烯酸粘结层的表面，UV 365nm～405nm波长光源下进行UV固化，形成聚氨酯丙烯酸酯层。
S106)、OCA成品制备：撕除上层丙烯酸粘结层的轻型离型膜，将上层丙烯酸粘结层贴合在已固化的聚氨酯丙烯酸酯层表面，形成最终的OCA胶。
对比例3
该对比例为一种OCA，其制备过程如下：
S101)、丙烯酸胶液制备：按重量配比将丙烯酸树脂42g、单体丙烯酸4-羟基丁酯2g、添加剂(3-甲基丙烯酰氧基丙基三甲氧基硅烷)2g组分混合，放入带有真空装置的高速率剪切分散混合仪器中，在真空条件下先以200转/每分钟速率混合5min，再以2000转/每分钟速率混合1min，罐装保存。
S102)、上层丙烯酸粘结层制备：在重型离型膜的一侧表面涂布丙烯酸胶液，然后加热80～150℃进行固化，同时表面覆轻型离型膜，得到一层丙烯酸粘结层。
S103)、下层丙烯酸粘结层制备：在轻型离型膜的一侧表面涂布丙烯酸胶液，然后加热80～150℃进行固化，同时表面覆轻型离型膜，得到另外一层丙烯酸粘结层。
S104)、聚氨酯丙烯酸酯浆料制备：将重均分子量为80000的聚氨酯丙烯酸酯、光引发剂按50g:1g的比例混合，放入带有真空装置的高速率剪切分散混合仪器中，在真空条件下先以200转/每分钟速率混合5min，再以2000转/每分钟速率混合1min，罐装保存。
S105)、聚氨酯丙烯酸酯层制备：撕除下层丙烯酸粘结层的轻型离型膜，将聚氨酯丙烯酸酯浆料涂布在下层丙烯酸粘结层的表面，UV 365nm～405nm波长光源下进行UV固化，形成聚氨酯丙烯酸酯层。
S106)、OCA成品制备：撕除上层丙烯酸粘结层的轻型离型膜，将上层丙烯酸粘结层贴合在已固化的聚氨酯丙烯酸酯层表面，形成最终的OCA胶。
分别测试不同实施例和对比例的OCA的各项性能，具体测试结果列于表1。其中，测试的具体项目以及具体的测试过程如下：
1)不同温度下的储能弹性模量：先制备好1mm厚度，15mm直径的圆片样品，离型膜去除，贴附在流变仪测试部位。按照正常流变仪测试步骤进行相应的设置，设置条件如下：温度：-40～100℃，升温速度5℃/min，应变：1％，频率：1HZ，轴向力：1N。测试弹性模量vs温度曲线。记录不同温度下对应的G’、G”和tanδ。
2)回复率：先制备好1mm厚度，15mm直径的圆片样品，离型膜去除，贴附在流变仪测试部位。按照正常流变仪测试步骤进行相应的设置，设置条件如下：25℃时，施加400％应变保持10min，然后撤销应力自然回复10min，10min后测试剩余应变值，计算公式如下：
Figure PCTCN2021103185-appb-000002
3)透光率：将带有离型膜的OCA裁切成4cm*4cm的胶块，去掉轻离型膜，贴在洁净的光学玻璃上，并用2KG滚压2-4次。然后脱泡机中去除气泡。按照正常分光光度计CM-3600A操作进行校准；用无尘布蘸酒精擦拭玻璃，去除玻璃面的脏污、灰尘等；将OCA上的重离型膜去除，将样品放入分光光度计进行测试。获得透光率。
4)雾度：参照透光率测试，利用分光光度计CM-3600A获得雾度值。
5)黄变指数b*：参照透光率测试，利用分光光度计CM-3600A获得黄变指数值。
6)与CPI的180°剥离力：将带有离型膜的OCA裁成2.5cm×5cm长条，CPI、PET膜裁成3cm×12cm长条。将CPI贴附在洁净玻璃上，再将OCA黏贴在CPI上(贴合前CPI表面进行空气plasma处理，水滴角＜40°)，撕去另外一层离型膜，将PET膜再贴在OCA上，并用2Kg滚轮以300mm/分的速度往返压合2次，要求贴合界面无气泡。再脱泡处理后静置24h。将样品置于拉力测试设备中，以300mm/min的速度180°剥离OCA胶，要求OCA胶与测试基板匀速剥离，以测试曲线中相对平稳区的力值为剥离力值，单位N/cm。
7)用于折叠屏中R2.5mm弯折20万次的外观性能：弯折后取出，显微镜观察样品表面是否存在气泡、OCA界面脱离等不良现象。
8)应力导致OLED屏其他膜层失效情况等：弯折后取出，显微镜观察样品表面是否存在裂纹等不良现象。
表1
Figure PCTCN2021103185-appb-000003
从表1中的数据可以看出，本申请实施例的OCA，其各项性能指标均优于对比例1-3。实施例1与对比例1相比，回复性及弯折寿命均更优。对比例1出现弯折后OCA气泡。
从对比例2和对比例3与实施例1-7的对比数据可以看出，当形成支撑层的聚氨酯丙烯酸酯的重均分子量不在本申请的范围内时，其综合性能并不能满足折叠屏对OCA的性能要求。
有上述实验数据可以看出，本申请实施例提供的OCA，可兼具高柔性、高回复性、高粘接性的特点，同时具有更优异的耐弯折性能。另外，本申请光学胶中的聚氨酯丙烯酸酯，透光性高、雾度低且不易黄变，在具有较好机械性能的基础上，还具有优异的光学性能。
此外，折叠屏相比直板手机，折叠屏的抗外应力能力更差。在受到类似落球、笔跌等外应力时容易出现屏失效。本申请实施例提供的可OCA作为屏内部主要的缓冲材料，需要承受一定的缓冲能力，提高屏的耐受能力。
以上，仅为本申请的具体实施方式，但本申请的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本申请揭露的技术范围内，可轻易想到变化或替换，都应涵盖在本申请的保护范围之内。因此，本申请的保护范围应以权利要求的保护范围为准。

Claims (26)

  1. 一种光学胶，其特征在于，包括至少一层支撑层，任一所述支撑层的两侧表面均设有粘结层，其中，所述支撑层中含有聚氨酯类聚合物，所述聚氨酯类聚合物的重均分子量为2000～60000。
  2. 根据权利要求1所述的光学胶，其特征在于，所述聚氨酯类聚合物包括第一聚氨酯丙烯酸酯，所述第一聚氨酯丙烯酸酯的重均分子量为2000～20000，25℃下的储能模量值E 25为5～80KPa。
  3. 根据权利要求2所述的光学胶，其特征在于，所述第一类聚氨酯丙烯酸酯在25℃下的储能模量值E 25>3×10 4Pa，60℃下的储能模量值E 60>2×10 4Pa，-20℃下的储能模量值E -20<2×10 5Pa，-40℃下的储能模量值E -40<1×10 6Pa。
  4. 根据权利要求2或3所述的光学胶，其特征在于，所述第一聚氨酯丙烯酸酯含有聚氨酯丙烯酸酯键和氢键。
  5. 根据权利要求2-4任一项所述的光学胶，其特征在于，所述第一聚氨酯丙烯酸酯包括氨基甲酸酯聚合物。
  6. 根据权利要求5所述的光学胶，其特征在于，所述氨基甲酸酯聚合物包括聚酯氨基甲酸酯、聚醚氨基甲酸酯、聚碳酸酯氨基甲酸酯或聚丙烯氨基甲酸酯中的至少一种。
  7. 根据权利要求2-6任一项所述的光学胶，其特征在于，所述聚氨酯类聚合物包括第二聚氨酯丙烯酸酯，所述第二聚氨酯丙烯酸酯的重均分子量为23000～60000，25℃下的储能模量值E 25为100～500KPa。
  8. 根据权利要求7所述的光学胶，其特征在于，所述第二聚氨酯丙烯酸酯在25℃下的储能模量值E 25>12×10 4Pa，60℃下的储能模量值E 60>5×10 4Pa，-20℃下的储能模量值E -20<5×10 5Pa，-40℃下的储能模量值E -40<3×10 6Pa。
  9. 根据权利要求7或8所述的光学胶，其特征在于，所述第二聚氨酯丙烯酸酯的断裂伸长率≥200％。
  10. 根据权利要求7-9任一项所述的光学胶，其特征在于，所述第二聚氨酯丙烯酸酯包括氨基甲酸酯聚合物。
  11. 根据权利要求10所述的光学胶，其特征在于，所述氨基甲酸酯聚合物包括聚酯氨基甲酸酯、聚醚氨基甲酸酯、聚碳酸酯氨基甲酸酯或聚丙烯氨基甲酸酯中的至少一种。
  12. 根据权利要求7-11任一项所述的光学胶，其特征在于，所述第一聚氨酯丙烯酸酯与所述第二聚氨酯丙烯酸酯的重量比为9:1～2:1。
  13. 根据权利要求1-12任一项所述的光学胶，其特征在于，所述支撑层的总厚度占所述光学胶总厚度的30％～80％。
  14. 根据权利要求1-13任一项所述的光学胶，其特征在于，所述支撑层的回复率>85％。
  15. 根据权利要求1-14任一项所述的光学胶，其特征在于，所述支撑层的可见光透光率>90％，雾度≤2％，黄变指数≤3。
  16. 根据权利要求1-15任一项所述的光学胶，其特征在于，所述粘结层中含有丙烯酸酯类粘结剂。
  17. 根据权利要求16所述的光学胶，其特征在于，所述丙烯酸酯类粘结剂包括丙烯酸酯和/或含有羟基的(甲基)丙烯酸酯。
  18. 根据权利要求17所述的光学胶，其特征在于，所述含有羟基的(甲基)丙烯酸酯包括2-羟乙基(甲基)丙烯酸酯、2-羟丙基(甲基)丙烯酸酯、4-羟丁基(甲基)丙烯酸酯、4-羟环己基(甲基)丙烯酸酯或5-羟环辛基(甲基)丙烯酸酯中至少一种。
  19. 根据权利要求16-18任一项所述的光学胶，其特征在于，所述粘结层中还包括以下共聚物中的至少一种：乙烯基共聚物、有机硅共聚物、烯烃共聚物、聚氨酯丙烯酸酯(甲基)丙烯酸酯或聚丁二烯二(甲基)丙烯酸酯。
  20. 一种光学胶的制备方法，其特征在于，包括：提供至少一支撑层，在任一所述支撑层的两侧分别形成粘结层；其中，所述支撑层中含有聚氨酯类聚合物，所述聚氨酯类聚合物的重均分子量为2000～60000。
  21. 根据权利要求20所述的制备方法，其特征在于，所述在任一所述支撑层的两侧分别形成粘结层，包括：
    在第一离型膜的表面涂覆胶液，固化后形成一层所述粘结层；
    在所述粘结层的表面涂覆聚氨酯类聚合物浆料，固化后形成所述支撑层；
    在第二离型膜的表面涂覆胶液，固化后形成另一层所述粘结层；
    将第二离型膜表面的所述粘结层贴合在所述支撑层的表面。
  22. 根据权利要求21所述的制备方法，其特征在于，将第一聚氨酯丙烯酸酯和第二聚氨酯丙烯酸酯以及光引发剂混合后，形成聚氨酯类聚合物浆料。
  23. 根据权利要求20所述的制备方法，其特征在于，所述在任一所述支撑层的两侧分别形成粘结层，包括：
    利用共挤工艺，同时共挤形成依次叠层设置的所述粘结层和所述支撑层。
  24. 一种显示屏，其特征在于，包括依次设置的透明盖板、偏光片、触摸屏和显示面板，其中，所述透明盖板与所述偏光片之间、所述偏光片与所述触摸屏之间、所述触摸屏与所述显示面板之间设有如权利要求1-19任一项所述的光学胶或利用如权利要求20-23任一项所述的制备方法得到的光学胶。
  25. 根据权利要求24所述的显示屏，其特征在于，所述显示屏为柔性显示屏。
  26. 一种终端设备，其特征在于，包括权利要求24或25所述的显示屏。
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