Display panel for AR (Augmented Reality) equipment, low-refractive-index epoxy filling adhesive and preparation method of low-refractive-index epoxy filling adhesive

Abstract

The invention provides an epoxy filling adhesive with a low refractive index, the epoxy filling adhesive is used for being coated between an OLED light-emitting layer and a glass cover plate of a display panel, and the epoxy filling adhesive comprises the following components in parts by mass: 1-79 parts of monofunctional fluorine-containing epoxy resin. And 1-79 parts of bifunctional fluorine-containing epoxy resin. And 1 to 50 parts of oxetane epoxy resin. And 0.1 to 1 part of a leveling agent. And 0.1 to 3 parts of an antioxidant additive. And 0.1 to 3 parts of a photoinitiator. The epoxy filling adhesive system contains fluorine atoms, the high electronegativity of the fluorine atoms enables the density of electron clouds around the fluorine atoms to be high, so that the polarizability of the epoxy filling adhesive is reduced, scattering and reflection of light rays when the light rays pass through the epoxy filling adhesive are reduced, the refractive index of the epoxy filling adhesive is reduced, and the refractive index of the epoxy filling adhesive is reduced. Therefore, when the light passes through the epoxy filling adhesive, the refracted positive visual angle is small, and the light is more concentrated when passing through the epoxy filling adhesive, the OLED light-emitting layer and the glass cover plate, so that the light-emitting brightness of the display panel is increased.

Description

Technical Field

[0001] The present disclosure relates to the field of AR display, and in particular to a display panel for AR equipment, a low-refractive-index epoxy filler and a preparation method thereof. Background Art

[0002] As augmented reality / virtual reality technology (referred to as "AR / VR") continues to expand in the market, OLED microdisplay technology products (also known as silicon-based OLED) have increasingly obvious commercial potential in the AR display field due to their excellent self-luminescence, thin thickness and light weight, and are therefore widely used in augmented reality (AR) display technology.

[0003] The AR field has a high demand for the brightness of the display products at a front viewing angle. At present, the high brightness demand is mainly met by increasing the brightness of the direct-type or side-type backlight, but this will also increase energy consumption and heat, and high backlight brightness will also cause the channel leakage current to deteriorate. From the prior art of patent publication number CN117897013A, it is known that the brightness of OLED panels is generally 1000-3000nit, which is far from meeting the high brightness requirement.

[0004] To this end, the patent publication number is CN118192127A-an array substrate and display panel, which forms a microlens structure at the position corresponding to the first transistor by setting a first opening in a first flat layer with a low refractive index at the position corresponding to the first transistor, and filling the first opening with a second flat layer with a high refractive index, so that the light passing through the microlens structure converges to improve the brightness of the light. Although the brightness of the light is improved by changing the structure on the OLED panel, the OLED light-emitting layer is generally coated with a layer of filling glue and then encapsulated with a glass cover plate, and the refractive index of conventional filling glue is generally greater than or equal to 1.5, resulting in a larger positive viewing angle of the light refracted when passing through the filling glue, which causes the light to be more dispersed, thereby reducing the brightness of the light output of the OLED panel. Summary of the invention

[0005] The purpose of the present disclosure is to overcome the deficiencies in the prior art and to provide a display panel for AR equipment with improved light output brightness, a low-refractive-index epoxy filler and a preparation method thereof.

[0006] The purpose of this disclosure is achieved through the following technical solutions:

[0007] A low-refractive-index epoxy filler is used for coating between an OLED light-emitting layer and a glass cover plate of a display panel, wherein the epoxy filler comprises the following components in parts by weight:

[0008]

[0009] In one embodiment, the monofunctional fluorinated epoxy resin is a combination of one or more of Compounds 1-42.

[0010] In one embodiment, the difunctional fluorinated epoxy resin is a combination of one or more of compounds 43-64.

[0011] In one embodiment, the oxetane epoxy resin is a combination of one or more of compounds 65-73.

[0012] In one embodiment, the leveling agent is a silicone leveling agent.

[0013] In one embodiment, the antioxidant auxiliary agent is a combination of one or more of trioctyl phosphite, trilauryl phosphite and tridecyl phosphite.

[0014] In one embodiment, the photoinitiator is an onium salt compound.

[0015] In one embodiment, the onium salt compound is a combination of one or more of diphenyl-(4-phenylthio)phenylsulfonium hexafluoroantimonate, bis[4-diphenylthiophenyl]sulfide dihexafluoroantimonate, diaryl iodonium salt, triaryl iodonium salt, alkyl iodonium salt and isopropyl ferrocenium hexafluorophosphate.

[0016] A method for preparing a low-refractive-index epoxy filling adhesive, used for the low-refractive-index epoxy filling adhesive described in any one of the above items;

[0017] The method for preparing the low-refractive-index epoxy filling adhesive comprises the following steps:

[0018] The monofunctional fluorinated epoxy resin, the difunctional fluorinated epoxy resin, the oxetane epoxy resin, the leveling agent, the antioxidant and the photoinitiator are mixed to obtain a precursor glue solution;

[0019] filtering the precursor gel solution;

[0020] The filtered precursor glue solution is subjected to centrifugal degassing treatment to obtain an epoxy filling glue with a low refractive index.

[0021] A display panel for an AR device comprises an OLED light-emitting layer, a glass cover plate, and a low-refractive-index epoxy filler prepared by the above-mentioned method for preparing a low-refractive-index epoxy filler, wherein the epoxy filler is coated between the OLED light-emitting layer and the glass cover plate, and the epoxy filler is used to form an epoxy filler layer between the OLED light-emitting layer and the glass cover plate after photocuring.

[0022] Compared with the prior art, the present invention has at least the following advantages:

[0023] 1. By adding monofunctional fluorine-containing epoxy resin and difunctional fluorine-containing epoxy resin to the epoxy filler system, fluorine atoms are contained in the epoxy filler system. The high electronegativity of fluorine atoms makes the electron cloud density around it higher, thereby reducing the polarizability of the epoxy filler. The reduction in the polarizability of the epoxy filler helps to reduce the scattering and reflection of light when passing through the epoxy filler, thereby reducing the refractive index of the epoxy filler, making the positive viewing angle of light refracted when passing through the epoxy filler smaller, and making the light more concentrated when passing through the epoxy filler, the OLED light-emitting layer and the glass cover, thereby increasing the brightness of the display panel.

[0024] 2. Monofunctional fluorinated epoxy resin and oxetane epoxy resin can enhance the adhesion of epoxy filler, so that the epoxy filler has better adhesion when coating the OLED light-emitting layer, and increase the connection stability between the epoxy filler and the OLED light-emitting layer, while the leveling agent can reduce the surface tension of the epoxy filler, increase the fluidity of the epoxy filler, so that the epoxy filler can be evenly coated on the OLED light-emitting layer, and the antioxidant additive can enhance the antioxidant performance of the epoxy filler, prevent the epoxy filler from being oxidized and degraded, and improve the stability of the epoxy filler. Furthermore, the addition of the photoinitiator causes the monofunctional fluorinated epoxy resin, difunctional fluorinated epoxy resin and oxetane epoxy resin in the system to cross-link and cure during photocuring of the epoxy filler, and the difunctional fluorinated epoxy resin can increase the curing speed, and at the same time effectively increase the hardness of the epoxy filler after curing, thereby improving the structural strength of the epoxy filler after curing.

[0025] 3. Each component in the epoxy filler system completes cross-linking and curing at its mass fraction, and an epoxy filler with strong adhesion, strong structural strength, strong antioxidant performance and low refractive index can be obtained. When the epoxy filler is coated on the OLED light-emitting layer, it can not only improve the light brightness of the display panel, but also improve the connection strength between the OLED light-emitting layer and the glass cover in the display panel, thereby improving the structural stability of the display panel. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present disclosure and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 Schematic diagram of the chemical structure of compounds 1 to 42 in the monofunctional fluorinated epoxy resin;

[0028] Figure 2Schematic diagram of the chemical structure of compounds 43 to 64 in the difunctional fluorinated epoxy resin;

[0029] Figure 3 Schematic diagram of the chemical structure of compounds 65 to 73 in the oxetane epoxy resin;

[0030] Figure 4 The figure is a schematic diagram of a process for preparing a low refractive index epoxy filler;

[0031] Figure 5 for Figure 4 A schematic flow chart of step S80 in the method for preparing low-refractive-index epoxy filling glue is shown;

[0032] Figure 6 for Figure 4 A schematic flow chart of step S90 in the method for preparing low-refractive-index epoxy filling glue is shown;

[0033] Figure 7 Schematic diagram of the chemical structure of compounds A1 to A3 in Class A;

[0034] Figure 8 Schematic diagram of the chemical structure formula of compounds B1 to B14 in Class B;

[0035] Fig. 9 Schematic diagram of the chemical structure of compounds C1 to C7 in the C class of compounds;

[0036] Fig.10 Schematic diagram of the synthesis principle of compound 16 and compound 49. DETAILED DESCRIPTION

[0037] In order to facilitate the understanding of the present disclosure, the present disclosure will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present disclosure are given in the drawings. However, the present disclosure can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present disclosure more thoroughly and comprehensively understood.

[0038] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present disclosure. The terms used herein in the specification of the present disclosure are only for the purpose of describing specific embodiments and are not intended to limit the present disclosure. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0040] The present disclosure provides a low-refractive-index epoxy filler for coating between an OLED light-emitting layer and a glass cover plate of a display panel, wherein the epoxy filler comprises the following components by weight: 1 to 79 parts of a monofunctional fluorinated epoxy resin, 1 to 79 parts of a difunctional fluorinated epoxy resin, 1 to 50 parts of an oxetane epoxy resin, 0.1 to 1 parts of a leveling agent, 0.1 to 3 parts of an antioxidant, and 0.1 to 3 parts of a photoinitiator.

[0041] In order to better understand the low refractive index epoxy filler disclosed in the present invention, the low refractive index epoxy filler is further explained as follows:

[0042] An epoxy filler with a low refractive index according to an embodiment of the present invention is used for coating between an OLED light-emitting layer and a glass cover plate of a display panel, wherein the epoxy filler comprises the following components in parts by weight:

[0043]

[0044] In this embodiment, by adding monofunctional fluorine-containing epoxy resin and difunctional fluorine-containing epoxy resin to the epoxy filler system, fluorine atoms are contained in the epoxy filler system. The high electronegativity of fluorine atoms makes the electron cloud density around it higher, thereby reducing the polarizability of the epoxy filler. The reduction in the polarizability of the epoxy filler helps to reduce the scattering and reflection of light when passing through the epoxy filler, thereby reducing the refractive index of the epoxy filler, making the positive viewing angle of the light refracted when passing through the epoxy filler smaller, and making the light more concentrated when passing through the epoxy filler, the OLED light-emitting layer and the glass cover, thereby increasing the light output brightness of the display panel.

[0045] Furthermore, the monofunctional fluorinated epoxy resin and the oxetane epoxy resin can enhance the adhesion of the epoxy filler, so that the epoxy filler has better adhesion when coating the OLED light-emitting layer, and increase the connection stability between the epoxy filler and the OLED light-emitting layer, while the leveling agent can reduce the surface tension of the epoxy filler, increase the fluidity of the epoxy filler, and enable the epoxy filler to be evenly coated on the OLED light-emitting layer, and the antioxidant additive can enhance the antioxidant performance of the epoxy filler, prevent the epoxy filler from being oxidized and degraded, and improve the stability of the epoxy filler. Furthermore, the addition of the photoinitiator allows the monofunctional fluorinated epoxy resin, the difunctional fluorinated epoxy resin and the oxetane epoxy resin in the system to cross-link and cure during photocuring of the epoxy filler, and the difunctional fluorinated epoxy resin can increase the curing speed, and at the same time effectively increase the hardness of the epoxy filler after curing, thereby improving the structural strength of the epoxy filler after curing.

[0046] Furthermore, each component in the epoxy filler system completes cross-linking and curing at its mass fraction, and an epoxy filler having strong adhesion, strong structural strength, strong antioxidant performance and low refractive index can be obtained, so that when the epoxy filler is coated on the OLED light-emitting layer, it can not only improve the light output brightness of the display panel, but also improve the connection strength between the OLED light-emitting layer and the glass cover in the display panel, thereby improving the structural stability of the display panel.

[0047] See also Figure 1 , in one embodiment, the monofunctional fluorinated epoxy resin is a combination of one or more of compounds 1 to 42. It is understandable that the monofunctional fluorinated epoxy resin can provide fluorine atoms to the epoxy filler system, and the high electronegativity of the fluorine atom makes the electron cloud density around it higher, which can reduce the polarizability of the epoxy filler. In addition, the monofunctional fluorinated epoxy resin contains highly reactive functional groups of epoxy groups, which can react with the active functional groups on the surface of the substrate to form a strong chemical bond, thereby improving the adhesion of the epoxy filler. Further, the monofunctional fluorinated epoxy resin has good permeability and can penetrate into the tiny gaps on the surface of the substrate. This penetration effect helps to improve the closer contact between the epoxy filler and the substrate, thereby enhancing the adhesion of the epoxy filler. Furthermore, the epoxy filler can fill the pores on the surface of the substrate, that is, the pores on the OLED light-emitting layer and the glass cover, forming a mechanical locking effect to improve the connection strength between the OLED light-emitting layer and the glass cover.

[0048] See also Figure 2In one embodiment, the difunctional fluorinated epoxy resin is a combination of one or more of compounds 43 to 64. It is understandable that the difunctional fluorinated epoxy resin can provide fluorine atoms to the epoxy filler system, and the high electronegativity of the fluorine atoms makes the electron cloud density around it higher, which can not only reduce the polarizability of the epoxy filler, but also attract the electron cloud, making the epoxy group more susceptible to attack and ring-opening reaction, and the difunctional fluorinated epoxy resin contains multiple epoxy groups, which can form more cross-linking points, thereby improving the curing speed of the epoxy filler. Furthermore, the fluorine atom has a smaller atomic radius and a higher electronegativity, which can make the interaction between the epoxy resin molecular chains closer, and make the three-dimensional network structure formed by the epoxy filler after light curing more stable, thereby effectively improving the hardness of the epoxy filler after curing, that is, improving the structural strength of the epoxy filler after curing.

[0049] See also Figure 3 In one embodiment, the oxetane epoxy resin is a combination of one or more of compounds 65 to 73. It is understandable that the oxetane epoxy resin has good bonding performance and good structural strength, so that the epoxy filler has good adhesion and good structural strength after curing, thereby effectively improving the connection stability between the OLED light-emitting layer and the glass cover.

[0050] In one embodiment, the leveling agent is a silicone leveling agent. It is understandable that the leveling agent can improve the surface tension of the epoxy filler, improve the leveling and uniformity of the epoxy filler, and also improve the permeability of the epoxy filler, so that the epoxy filler can be evenly filled between the OLED light-emitting layer and the glass cover plate, ensuring that the OLED light-emitting layer and the glass cover plate have good connection strength. Further, in this embodiment, the leveling agent is a silicone leveling agent BYK-333.

[0051] In one embodiment, the antioxidant is a combination of one or more of trioctyl phosphite, trilauryl phosphite and tridecyl phosphite. It is understood that the antioxidant can enhance the antioxidant properties of the epoxy filler, prevent the epoxy filler from being oxidized and degraded after curing, and cause structural collapse, thereby ensuring the structural stability of the epoxy filler after curing.

[0052] In one embodiment, the photoinitiator is an onium salt compound. It is understandable that the photoinitiator is also called a photocuring agent, which causes the epoxy filler to generate free radicals, cations, etc. after absorbing energy, triggering a polymerization reaction, and causing the epoxy groups to cross-link and solidify. Furthermore, the onium salt compound belongs to a cationic photoinitiator. After the onium salt compound is activated by light, the molecule is in an excited state, the molecule undergoes a decomposition reaction, and a super strong proton acid is generated, which triggers the epoxy group to undergo a polymerization reaction, so that the epoxy filler is cured and cross-linked.

[0053] In one embodiment, the onium salt compound is a combination of one or more of diphenyl-(4-phenylthio)phenylsulfonium hexafluoroantimonate, bis[4-diphenylthiophenyl]sulfide dihexafluoroantimonate, diaryl iodonium salt, triaryl iodonium salt, alkyl iodonium salt and isopropyl ferrocenium hexafluorophosphate.

[0054] See also Figure 4 The present disclosure also provides a method for preparing a low-refractive-index epoxy filling adhesive, which is used for the low-refractive-index epoxy filling adhesive described in any of the above items.

[0055] The method for preparing the low-refractive-index epoxy filling adhesive comprises the following steps:

[0056] S100, a monofunctional fluorinated epoxy resin, a difunctional fluorinated epoxy resin, an oxetane epoxy resin, a leveling agent, an antioxidant and a photoinitiator are mixed to obtain a precursor glue.

[0057] In this embodiment, monofunctional fluorinated epoxy resin, difunctional fluorinated epoxy resin, oxetane epoxy resin, leveling agent, antioxidant aid and photoinitiator are added into a stirring kettle according to the above-mentioned mass fractions and stirred to obtain a precursor glue solution, and a uniformly dispersed precursor glue solution can be formed under the mass fractions of each component, thereby ensuring the uniformity of the epoxy filling glue.

[0058] Furthermore, the temperature of the mixing process is 20-30° C. In this embodiment, the temperature of the mixing process is 25° C.

[0059] S200, filtering the precursor gel solution.

[0060] In this embodiment, the viscosity of the precursor glue can be effectively controlled by filtering the precursor glue, thereby ensuring that the epoxy filling glue has excellent performance and good fluidity, thereby effectively improving the performance and dispersion uniformity of the epoxy filling glue.

[0061] S300, performing centrifugal degassing on the filtered precursor glue to obtain a low-refractive-index epoxy filling glue.

[0062] In this embodiment, the filtered precursor glue is placed in a centrifuge for centrifugation to remove bubbles in the precursor glue and further improve the mixing uniformity of the precursor glue so that the substances in the epoxy filler glue system can be evenly dispersed.

[0063] In one embodiment, the specific steps of filtering the precursor gel are as follows:

[0064] Performing a first filtration treatment on the precursor gel on a filter membrane;

[0065] The precursor gel solution after the first filtering treatment is subjected to a second filtering treatment on the filtering membrane.

[0066] It should be noted that the pore size of the filter membrane is 0.5 μm, and after two filtration treatments, the precursor glue can be ensured to have a relatively stable viscosity. Further, the viscosity of the precursor glue after the second filtration treatment is 5 to 20 cps, and the viscosity of the precursor glue is controlled between 5 and 20 cps, so that the epoxy filler has relatively excellent performance and good fluidity, and can be evenly dispersed between the OLED light-emitting layer and the glass cover.

[0067] like Figure 4 As shown, in one embodiment, before the step of mixing the monofunctional fluorinated epoxy resin, the difunctional fluorinated epoxy resin, the oxetane epoxy resin, the leveling agent, the antioxidant and the photoinitiator, the method for preparing the low refractive index epoxy filler further includes the following steps:

[0068] S80, preparing monofunctional fluorinated epoxy resin;

[0069] S90, preparing a difunctional fluorinated epoxy resin.

[0070] It should be noted that by preparing a monofunctional fluorinated epoxy resin, not only can fluorine atoms be provided to the epoxy filler system, but also the adhesion of the epoxy filler can be enhanced, so that the adhesion of the epoxy filler when coated on the OLED light-emitting layer and the glass cover is effectively improved, thereby improving the connection strength between the OLED light-emitting layer and the glass cover. Further, by preparing a difunctional fluorinated epoxy resin, not only can fluorine atoms be provided to the epoxy filler system, but also the curing speed and hardness of the epoxy filler can be improved, so that the epoxy filler can quickly form an epoxy filler layer with good structural strength under light, further improving the connection strength between the OLED light-emitting layer and the glass cover.

[0071] For further information, see Figure 5 In one embodiment, step S80 is specifically:

[0072] S81, adding the Class A compound, the Class B compound, the catalyst, water and potassium hydroxide in a molar ratio of 1:1:0.05:7.78:1.15 into a stirring reactor for a first stirring reaction treatment.

[0073] In this embodiment, the A compound, the B compound, the catalyst, water and potassium hydroxide are stirred and mixed according to this molar ratio, and the A compound and the B compound are fully reacted under the catalyst and alkaline conditions to obtain a precursor liquid of a monofunctional fluorine-containing epoxy resin.

[0074] It should be noted that the A-type compound and the B-type compound are first added into the stirring reactor, and then the catalyst and the potassium hydroxide solution are added for stirring reaction to obtain a precursor liquid of the monofunctional fluorine-containing epoxy resin. In this embodiment, the temperature of the first stirring reaction treatment is 80-85° C., and the time of the first stirring reaction treatment is 7-8 hours.

[0075] S82, adding water into the stirred reactor after the first stirring reaction treatment, and performing a first liquid separation operation on the feed liquid in the stirred reactor using a separating funnel to obtain a first lower layer solution.

[0076] In this embodiment, a proper amount of water is added into the stirring reactor, and the liquid in the stirring reactor is separated into layers. The first lower layer solution is separated out by a separating funnel to obtain a first lower layer solution containing a monofunctional fluorinated epoxy resin.

[0077] S83, performing acid titration treatment on the first lower layer solution to adjust the pH value of the first lower layer solution to between 6 and 7.

[0078] In this embodiment, the first lower layer solution is titrated with a 1 mol / L dilute sulfuric acid standard titration solution to ensure that the pH value of the first lower layer solution is between 6 and 7.

[0079] S84, placing the first lower layer solution after the acid titration treatment in a rotary evaporator for a first rotary evaporation treatment to obtain a monofunctional fluorine-containing epoxy resin.

[0080] In this embodiment, the first lower layer solution is evaporated and concentrated in a rotary evaporator to obtain a monofunctional fluorine-containing epoxy resin in a transition bottle.

[0081] It should be noted that the pressure of the first rotary evaporation treatment is -0.1 MPa, and the temperature of the first rotary evaporation treatment is 160°C.

[0082] For further information, see Figure 6 In one embodiment, step S90 is specifically:

[0083] S91, adding the Class A compound, the Class C compound, the catalyst, water and potassium hydroxide in a molar ratio of 2:1:0.05:7.78:1.15 into a stirring reactor for a second stirring reaction treatment.

[0084] In this embodiment, the A compound, the C compound, the catalyst, water and potassium hydroxide are stirred and mixed according to this molar ratio, and the A compound and the C compound are fully reacted under the catalyst and alkaline conditions to obtain a precursor liquid of a difunctional fluorinated epoxy resin.

[0085] It should be noted that the A-type compound and the C-type compound are first added into the stirring reactor, and then the catalyst and the potassium hydroxide solution are added for stirring reaction to obtain a precursor liquid of the difunctional fluorinated epoxy resin. In this embodiment, the temperature of the second stirring reaction treatment is 80-85° C., and the time of the second stirring reaction treatment is 7-8 hours.

[0086] S92, adding water into the stirred reactor after the second stirring reaction treatment, and performing a second liquid separation operation on the liquid in the stirred reactor using a separating funnel to obtain a second lower layer solution.

[0087] In this embodiment, a proper amount of water is added into the stirred reactor, and the feed liquid in the stirred reactor is separated into layers. The second lower layer solution is separated out by a separating funnel to obtain a second lower layer solution containing a difunctional fluorinated epoxy resin.

[0088] S93, performing acid titration treatment on the second lower layer solution to adjust the pH value of the second lower layer solution to between 6 and 7.

[0089] In this embodiment, the second lower layer solution is titrated with a 1 mol / L dilute sulfuric acid standard titration solution to ensure that the pH value of the second lower layer solution is between 6 and 7.

[0090] S94, placing the second lower layer solution after the acid titration treatment in a rotary evaporator for a second rotary evaporation treatment to obtain a difunctional fluorine-containing epoxy resin.

[0091] In this embodiment, the second lower layer solution is evaporated and concentrated in a rotary evaporator to obtain a difunctional fluorine-containing epoxy resin in a transition bottle.

[0092] It should be noted that the pressure of the second rotary evaporation treatment is -0.1 MPa, and the temperature of the second rotary evaporation treatment is 160°C.

[0093] like Figure 7 As shown, in one embodiment, the Class A compound is one of compounds A1-A3.

[0094] like Figure 8As shown, in one embodiment, the Class B compound is one of compounds B1-B14.

[0095] like Fig. 9 As shown, in one embodiment, the C-type compound is one of compounds C1-C7.

[0096] In one embodiment, the catalyst is tetrabutylammonium bromide.

[0097] The present disclosure also provides a display panel for an AR device, comprising an OLED light-emitting layer, a glass cover plate, and a low-refractive-index epoxy filler prepared by the low-refractive-index epoxy filler preparation method described above, wherein the epoxy filler is coated between the OLED light-emitting layer and the glass cover plate, and the epoxy filler is used to form an epoxy filler layer between the OLED light-emitting layer and the glass cover plate after photocuring.

[0098] In this embodiment, a low-refractive-index epoxy filler is coated on the OLED light-emitting layer and the glass cover plate, which can not only reduce the refractive index of the display panel, but also enhance the connection strength between the OLED light-emitting layer and the glass cover plate, thereby effectively improving the light output brightness and structural stability of the display panel.

[0099] Examples are listed below, but it should be noted that the following examples do not exhaust all possible situations, and the materials used in the following examples can be obtained from commercial channels unless otherwise specified.

[0100] Example 1

[0101] Step 1: Prepare a monofunctional fluorine-containing epoxy resin compound 16, wherein the molar ratio of A1, B6, catalyst, water, and KOH is 1:1:0.05:7.78:1.15. First, add A1 and B6 to a stirred reactor, then add the catalyst tetrabutylammonium bromide, and then add the prepared KOH aqueous solution, stir at 85°C for 8 hours. After the reaction is completed, add an appropriate amount of water to the stirred reactor, and then separate the liquid with a separatory funnel. Take the lower layer solution. Titrate the first lower layer solution to a pH value of 7 with a 1mol / L dilute sulfuric acid standard titration solution. The first lower layer solution is rotary evaporated by a rotary evaporator at -0.1Mpa and 160°C to obtain the monofunctional fluorine-containing epoxy resin compound 16 in a transition bottle.

[0102] Step 2: Prepare a difunctional fluorinated epoxy resin compound 49, wherein the molar ratio of A1, C3, catalyst, water, and KOH is 2:1:0.05:7.78:1.15. First, add A1 and C3 to a stirred reactor, then add the catalyst tetrabutylammonium bromide, and then add the prepared KOH aqueous solution, stir at 85°C for 8 hours. After the reaction is completed, add an appropriate amount of water to the stirred reactor, and then separate the liquid with a separatory funnel. Take the lower layer solution. Titrate the first lower layer solution to a pH value of 7 with a 1mol / L dilute sulfuric acid standard titration solution. The first lower layer solution is rotary evaporated by a rotary evaporator at -0.1Mpa and 160°C to obtain the prepared difunctional fluorinated epoxy resin compound 49 in a transition bottle.

[0103] Step 3: The monofunctional fluorinated epoxy resin compound 16, the difunctional fluorinated epoxy resin compound 49, the oxetane epoxy resin compound 65, the leveling agent BYK333, trioctyl phosphite and diphenyl-(4-phenylthio)phenylsulfonium hexafluoroantimonate are mixed to obtain a precursor glue, wherein the mass fraction of the monofunctional fluorinated epoxy resin compound 16 is 30 parts, the mass fraction of the difunctional fluorinated epoxy resin compound 49 is 50 parts, the mass fraction of the oxetane epoxy resin compound 65 is 20 parts, the mass fraction of the leveling agent BYK333 is 0.5 parts, the mass fraction of the antioxidant-trioctyl phosphite is 0.5 parts, and the mass fractions of the photoinitiator-trioctyl phosphite and diphenyl-(4-phenylthio)phenylsulfonium hexafluoroantimonate are 1 part.

[0104] Step 4: Use a 0.5 μm filter membrane to filter the precursor gel twice.

[0105] Step 5: The filtered precursor glue solution is subjected to centrifugal degassing treatment to obtain a low-refractive-index epoxy filling glue.

[0106] Example 2

[0107] The difference from Example 1 is that the mass fraction of the monofunctional fluorine-containing epoxy resin compound 16 is 40 parts, and the mass fraction of the difunctional fluorine-containing epoxy resin compound 49 is 40 parts.

[0108] Example 3

[0109] The difference from Example 1 is that the mass fraction of the monofunctional fluorine-containing epoxy resin compound 16 is 50 parts, and the mass fraction of the difunctional fluorine-containing epoxy resin compound 49 is 30 parts.

[0110] Example 4

[0111] The difference from Example 1 is that the mass fraction of the monofunctional fluorine-containing epoxy resin compound 16 is 60 parts, and the mass fraction of the difunctional fluorine-containing epoxy resin compound 49 is 20 parts.

[0112] Example 5

[0113] The difference from Example 1 is that the mass fraction of the monofunctional fluorine-containing epoxy resin compound 16 is 70 parts, and the mass fraction of the difunctional fluorine-containing epoxy resin compound 49 is 10 parts.

[0114] Example 6

[0115] The difference from Example 1 is that the mass fraction of the monofunctional fluorine-containing epoxy resin compound 16 is 75 parts, and the mass fraction of the difunctional fluorine-containing epoxy resin compound 49 is 5 parts.

[0116] Example 7

[0117] The difference from Example 1 is that the mass fraction of the monofunctional fluorine-containing epoxy resin compound 16 is 79 parts, and the mass fraction of the difunctional fluorine-containing epoxy resin compound 49 is 1 part.

[0118] Example 8

[0119] The difference from Example 1 is that the mass fraction of the monofunctional fluorine-containing epoxy resin compound 16 is 20 parts, and the mass fraction of the difunctional fluorine-containing epoxy resin compound 49 is 60 parts.

[0120] Example 9

[0121] The difference from Example 1 is that the mass fraction of the monofunctional fluorine-containing epoxy resin compound 16 is 10 parts, and the mass fraction of the difunctional fluorine-containing epoxy resin compound 49 is 70 parts.

[0122] Example 10

[0123] The difference from Example 1 is that the mass fraction of the monofunctional fluorine-containing epoxy resin compound 16 is 5 parts, and the mass fraction of the difunctional fluorine-containing epoxy resin compound 49 is 75 parts.

[0124] Embodiment 11

[0125] The difference from Example 1 is that the mass fraction of the monofunctional fluorine-containing epoxy resin compound 16 is 1 part, and the mass fraction of the difunctional fluorine-containing epoxy resin compound 49 is 79 parts.

[0126] Comparative Example 1

[0127] The difference from Example 1 is that the monofunctional fluorinated epoxy resin compound 16 and the difunctional fluorinated epoxy resin compound 49 are omitted, and an oxetane epoxy resin compound 65 and an oxetane epoxy resin compound 66 are added, wherein the mass fraction of the oxetane epoxy resin compound 65 is 70 parts, and the mass fraction of the oxetane epoxy resin compound 66 is 10 parts.

[0128] Comparative Example 2

[0129] The difference from Example 1 is that the mass fraction of the monofunctional fluorine-containing epoxy resin compound 16 is 80 parts, and the difunctional fluorine-containing epoxy resin compound 49 is not contained.

[0130] Comparative Example 3

[0131] The difference from Example 1 is that the monofunctional fluorine-containing epoxy resin compound 16 is not contained, and the mass fraction of the difunctional fluorine-containing epoxy resin compound 49 is 80 parts.

[0132] Comparative Example 4

[0133] The difference from Example 1 is that step 4 is missing.

[0134] Comparative Example 5

[0135] The difference from Example 1 is that step 5 is missing.

[0136] In 1kw UV mercury lamp and strong light curing UV energy is 3000-4000mj / cm 2 The epoxy filling adhesive was light-cured under the conditions and the performance test shown in Table 1 was carried out.

[0137] Table 1

[0138]

[0139]

[0140] Table 2

[0141]

[0142] Table 3

[0143]

[0144] It can be seen from Tables 1 to 3 that the hardness of the epoxy filler disclosed in the present invention after curing is 40A-80A, and it can exert its best performance under this hardness.

[0145] It can be seen from Table 2 and Table 3 that by comparing the data of Examples 1 to 11 and the data of Comparative Example 1, compared with the traditional epoxy filler, the epoxy filler disclosed in the present invention has a lower refractive index, higher light transmittance, higher light output brightness and higher adhesion, which greatly improves the light output brightness and structural stability of the AR display device, thereby effectively improving the clarity and contrast of the AR display device. Further, Example 5 is the best example.

[0146] It can be seen from Table 2 and Table 3 that by comparing the data of Examples 1 to 9, the epoxy filling glue formed by the monofunctional fluorinated epoxy resin and the difunctional fluorinated epoxy resin at their corresponding mass fractions has a lower refractive index, a higher light transmittance, a higher light output brightness and a higher adhesion. Furthermore, as the mass fraction of the difunctional fluorinated epoxy resin increases, the hardness of the epoxy filler will increase, especially in Example 10, Example 11 and Comparative Example 3, the hardness has exceeded 80A. It can be seen from the data of Example 10, Example 11 and Comparative Example 3 that too high hardness will lead to a decrease in adhesion, and will also lead to an increase in the refractive index of the epoxy filler, a decrease in the light output brightness and a decrease in the transmittance. This also shows that a filler that is too hard will affect the transmittance and refractive index of the OLED panel, resulting in a decrease in the display effect, affecting the high definition and high contrast of the AR display device. An epoxy filler that is too hard is prone to cracks when subjected to hot and cold shocks, causing water vapor to penetrate from the cracks, affecting the moisture resistance and service life of the AR display device. At the same time, if the hardness of the cured epoxy filler is too high, it is difficult to repair, that is, the repair is difficult, and the original performance and appearance of the epoxy filler will be affected after the repair. Furthermore, if the content of the difunctional fluorinated epoxy filler is too high, the transmittance of the epoxy filler after curing will be lower than 98%, especially in Example 8, Example 9, Example 10, Example 11 and Comparative Example 3. Therefore, the mass fraction of the difunctional fluorinated epoxy filler is preferably 5 to 50 parts.

[0147] It can be seen from Table 2 and Table 3 that by comparing the data of Examples 1 to 9, as the mass fraction of the monofunctional fluorinated epoxy resin increases, the refractive index of the epoxy filler decreases, so that the light output brightness of the epoxy filler is effectively improved, thereby being able to improve the light output brightness of the OLED panel, and effectively improving the clarity and contrast of the AR display device. Furthermore, as the mass fraction of the monofunctional fluorinated epoxy resin increases, the curing shrinkage of the epoxy filler increases, especially in Example 6, Example 7 and Comparative Example 2, the curing shrinkage is greater than or equal to 3%, and too high a curing shrinkage will cause cracks or stress concentration inside the cured epoxy filler, thereby reducing the tensile strength and compressive strength of the epoxy filler, and further reducing the reliability of the epoxy filler. Furthermore, as the mass fraction of the monofunctional fluorinated epoxy resin increases, the hardness of the epoxy filler will decrease, especially in Example 7 and Comparative Example 2, the hardness is already lower than 40A. Although it can reduce the refractive index and increase the brightness of the light, the structural stability of the epoxy filler is poor, especially the cured epoxy filler layer is easy to wear, thereby reducing the structural stability of the AR display device and affecting the service life of the AR display device. Furthermore, the mass fraction of the monofunctional fluorinated epoxy resin is preferably 30 to 75 parts.

[0148] It can be seen from Table 2 and Table 3 that by comparing the data of Example 1 and Comparative Example 4, the viscosity of the epoxy filler that has not been filtered through a 0.5 μm filter membrane is reduced, and the adhesion after curing is also significantly reduced, which also shows that impurities and pollutants will affect the interaction between molecules, resulting in reduced viscosity or even failure to adhere. Furthermore, pollutants (such as grease, silicone oil or lubricants, etc.) will form a thin film on the adhesive contact surface, blocking the bonding effect between the epoxy filler and the bonding surface, reducing the adhesion of the epoxy filler after curing, thereby reducing the structural connection strength of the AR display device, and then reducing the structural stability of the AR display device. Furthermore, other pollutants (such as acid, alkali or water, etc.) will reduce its viscosity during the curing process of the epoxy filler, thereby reducing the adhesion of the epoxy filler after curing. It can be seen that impurities and pollutants will reduce the strength and content of the epoxy filler, thereby affecting the mechanical properties of the epoxy filler.

[0149] It can be seen from Table 2 and Table 3 that by comparing the data of Example 1 and Comparative Example 5, the mechanical properties of the epoxy filling glue that has been treated with centrifugal degassing and that that has not been treated with centrifugal degassing are not much different, but there are slight differences in the refractive index and light brightness. This also shows that the refractive index of the epoxy filling glue after centrifugal degassing is relatively low, and the light brightness is relatively higher.

[0150] Compared with the prior art, the present invention has at least the following advantages:

[0151] 1. By adding monofunctional fluorine-containing epoxy resin and difunctional fluorine-containing epoxy resin to the epoxy filler system, fluorine atoms are contained in the epoxy filler system. The high electronegativity of fluorine atoms makes the electron cloud density around it higher, thereby reducing the polarizability of the epoxy filler. The reduction in the polarizability of the epoxy filler helps to reduce the scattering and reflection of light when passing through the epoxy filler, thereby reducing the refractive index of the epoxy filler, making the positive viewing angle of light refracted when passing through the epoxy filler smaller, and making the light more concentrated when passing through the epoxy filler, the OLED light-emitting layer and the glass cover, thereby increasing the brightness of the display panel.

[0152] 2. Monofunctional fluorinated epoxy resin and oxetane epoxy resin can enhance the adhesion of epoxy filler, so that the epoxy filler has better adhesion when coating the OLED light-emitting layer, and increase the connection stability between the epoxy filler and the OLED light-emitting layer, while the leveling agent can reduce the surface tension of the epoxy filler, increase the fluidity of the epoxy filler, so that the epoxy filler can be evenly coated on the OLED light-emitting layer, and the antioxidant additive can enhance the antioxidant performance of the epoxy filler, prevent the epoxy filler from being oxidized and degraded, and improve the stability of the epoxy filler. Furthermore, the addition of the photoinitiator causes the monofunctional fluorinated epoxy resin, difunctional fluorinated epoxy resin and oxetane epoxy resin in the system to cross-link and cure during photocuring of the epoxy filler, and the difunctional fluorinated epoxy resin can increase the curing speed, and at the same time effectively increase the hardness of the epoxy filler after curing, thereby improving the structural strength of the epoxy filler after curing.

[0153] 3. Each component in the epoxy filler system completes cross-linking and curing at its mass fraction, and an epoxy filler with strong adhesion, strong structural strength, strong antioxidant performance and low refractive index can be obtained. When the epoxy filler is coated on the OLED light-emitting layer, it can not only improve the light brightness of the display panel, but also improve the connection strength between the OLED light-emitting layer and the glass cover in the display panel, thereby improving the structural stability of the display panel.

[0154] The above-mentioned embodiments only express several implementation methods of the present disclosure, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the disclosed patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present disclosure, and these all belong to the protection scope of the present disclosure. Therefore, the protection scope of the disclosed patent shall be subject to the attached claims.

Claims

1. A low refractive index epoxy filler for coating between the OLED light-emitting layer and the glass cover of a display panel, characterized in that: Includes the following components by mass:

2. The low refractive index epoxy filler according to claim 1, characterized in that: The monofunctional fluorine-containing epoxy resin is a combination of one or more of compounds 1 to 42.

3. The low refractive index epoxy filler according to claim 1, characterized in that: The difunctional fluorine-containing epoxy resin is a combination of one or more of compounds 43 to 64.

4. The low refractive index epoxy filler according to claim 1, characterized in that: The oxetane epoxy resin is a combination of one or more of compounds 65 to 73.

5. The low refractive index epoxy filler according to claim 1, characterized in that: The leveling agent is an organic silicon leveling agent.

6. The low refractive index epoxy filler according to claim 1, characterized in that: The antioxidant auxiliary agent is a combination of one or more of trioctyl phosphite, trilauryl phosphite and tridecyl phosphite.

7. The low refractive index epoxy filler according to claim 1, characterized in that: The photoinitiator is an onium salt compound.

8. The low refractive index epoxy filler according to claim 7, characterized in that: The onium salt compound is a combination of one or more of diphenyl-(4-phenylthio)phenylsulfonium hexafluoroantimonate, bis[4-diphenylthiophenyl]sulfide dihexafluoroantimonate, diaryl iodonium salt, triaryl iodonium salt, alkyl iodonium salt and isopropyl ferrocenium hexafluorophosphate.

9. A method for preparing a low-refractive-index epoxy filler, characterized in that: Used to prepare the low refractive index epoxy filling glue according to any one of claims 1 to 8; The method for preparing the low-refractive-index epoxy filling adhesive comprises the following steps: The monofunctional fluorinated epoxy resin, the difunctional fluorinated epoxy resin, the oxetane epoxy resin, the leveling agent, the antioxidant and the photoinitiator are mixed to obtain a precursor glue solution; filtering the precursor gel; The filtered precursor glue solution is subjected to centrifugal degassing treatment to obtain an epoxy filling glue with a low refractive index.

10. A display panel for an AR device, characterized in that: It comprises an OLED light-emitting layer, a glass cover plate, and a low-refractive-index epoxy filler prepared by the method for preparing a low-refractive-index epoxy filler according to claim 9, wherein the epoxy filler is coated between the OLED light-emitting layer and the glass cover plate, and the epoxy filler is used to form an epoxy filler layer between the OLED light-emitting layer and the glass cover plate after photocuring.

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