Resin composition for optically transparent adhesive and method for improving adhesive force of the same

Abstract

To provide an optically transparent adhesive which has excellent optical characteristics, mechanical characteristics and hydrolysis stability, is stable and has low modulus, an optical laminate containing the adhesive, a method for improving adhesive force of the optically transparent adhesive, and a flexible display.SOLUTION: An optically transparent adhesive (OCA) contains a polymer resin composition. The polymer resin composition contains 30 to 60 wt.% of a thiol monomer, 20 to 60 wt.% of at least one of a vinyl monomer and an allyl monomer, and 10 to 30 wt.% of a bifunctional aliphatic urethane oligomer. The polymer resin composition further contains 1 to 3 wt.% of a hydrolysis stabilizer additive, 1 to 5 wt.% of a glycidyl monomer having at least one of an allyl functional group and an acrylate functional group, 0.1 to 1 wt.% of a cyclic azasilane monomer, 0.5 to 2 wt.% of a photoinitiator, and 0.01 to 0.03 wt.% of a wetting agent.SELECTED DRAWING: Figure 1

Description

background

[0001] The use of foldable plastic-based electronic devices has become increasingly popular in recent years. Optically clear adhesives (OCAs) play an important role in maintaining flexibility and reducing stress on display components when devices are folded at different temperatures. These adhesives must have high optical transparency (>90%) and long-term reliability with minimal yellowing when exposed to heat, humidity, and UV light. Current polyacrylate-based OCAs have difficulty achieving the desired low storage modulus in the temperature range of -20°C to 60°C. Furthermore, when exposed to harsh weathering conditions, acrylate-based OCAs are prone to network stability issues, making it difficult to maintain the desired optical and thermomechanical properties over long periods of time under high humidity and high temperature conditions. On the other hand, thiol-click-based OCAs can achieve a low storage modulus of 0.2 or less in the temperature range of -20°C to 60°C and maintain mechanical performance even under weathering conditions of 65°C and 90% humidity. However, achieving high adhesion levels of over 1000 gf / inch without substrate pretreatment remains a challenge. [Brief explanation of the drawings]

[0002] For a more complete understanding of the features and advantages of the present disclosure, reference should be made to the following detailed description taken in conjunction with the drawings, in which corresponding reference numerals refer to corresponding parts in the different views.

[0003] [Figure 1] 1 is a cross-sectional view of an optical stack according to a specific embodiment of the present disclosure. [Figure 2] 1 is a cross-sectional view of a flexible display according to a specific embodiment of the present disclosure.

[0004] The illustrated diagrams are for illustrative purposes only and are not intended to assert or imply any limitations with respect to the environment, architecture, design, or process in which different embodiments may be implemented. DETAILED DESCRIPTION OF THE INVENTION

[0005] This disclosure relates generally to materials related to the field of resin compositions for flexible display technology, and in particular to methods for improving the adhesion of optically clear adhesives (OCAs). In this disclosure, the term "adhesive" includes both permanent and pressure-sensitive adhesives. Pressure-sensitive adhesives are repositionable and can function as permanent adhesives through post-application treatment, such as UV exposure or heat.

[0006] Furthermore, in this disclosure, "optically clear" refers to a material having a haze value of approximately 2% or less over the wavelength range of 400 to 700 nm and a visible light transmittance of approximately 90% or more. Haze can be measured in accordance with JIS K 7136 (2000), and visible light transmittance can be measured in accordance with JIS K 7361 (1997). The term "optically clear" generally refers to a state in which no bubbles are visually observed. Furthermore, in this disclosure, "storage modulus (G')" refers to the storage modulus of a material when viscoelasticity is measured in a 1.0 Hz shear mode in a temperature range of -20°C to 60°C at a temperature rise rate of 5°C / min. The method disclosed herein forms a stable, low-modulus, optically clear adhesive with excellent optical properties, mechanical properties, and hydrolysis resistance.

[0007] While the making and using of various embodiments of the present disclosure are described in detail below, it should be understood that the present disclosure provides many applicable inventive concepts that can be embodied in a wide variety of specific situations. The specific embodiments discussed are illustrative only and do not limit the scope of the present disclosure. In the interest of clarity, not all features of an actual embodiment are described in this disclosure.

[0008] Unless otherwise indicated, all numerical values ​​in this specification and the related claims expressing quantities of ingredients, properties such as molecular weights, reaction conditions, and the like, are understood to be modified by the word "about." Accordingly, unless otherwise indicated, the numerical parameters set forth in this specification and the appended claims are approximations that may vary depending upon the properties of interest. At the very least, and without intending to limit the scope of the doctrine of equivalents to the scope of the claims, each numerical parameter should be construed based on the number of reported significant digits and by applying ordinary rounding approaches. It should be noted that when "about" appears at the beginning of a numerical series, the term "about" applies to every number in that series. Furthermore, in describing numerical ranges, the stated lower limit may be greater than the upper limit, but one of ordinary skill in the art will recognize that he or she must select an upper limit that is greater than the selected lower limit.

[0009] Disclosed herein is an optically clear adhesive (OCA) having a polymer resin composition adapted for incorporation into flexible display technology. The polymer resin composition comprises 30-60 wt% thiol monomer, 20-60 wt% at least one of vinyl monomer and allyl monomer, and 10-30 wt% difunctional aliphatic urethane oligomer. The polymer resin composition further comprises 1-3 wt% hydrolysis stabilizer additive, 1-5 wt% glycidyl monomer having at least one allyl or acrylate functional group, 0.1-1 wt% cyclic azasilane monomer, 0.5-2 wt% photoinitiator, and 0.01-0.03 wt% wetting agent. For application in flexible display technology, the polymer resin composition is cured into a film.

[0010] Further disclosed herein is an optical laminate comprising a first substrate layer having a first surface, a second substrate layer having a second surface, and an adhesive layer, wherein the adhesive layer comprises the optically transparent adhesive described in the preceding paragraph, is disposed between the first surface of the first substrate layer and the second surface of the second substrate layer, and is configured to adhere the first surface of the first substrate layer to the second surface of the second substrate layer.

[0011] Further disclosed herein is a flexible display comprising a window layer, a polarizer layer, a display layer, a support film layer, and a plurality of adhesive layers, each of which comprises the optically transparent adhesive described in the preceding paragraph, wherein a first adhesive layer of the plurality of adhesive layers is disposed between a first surface of the window layer and a first surface of the polarizer layer, a second adhesive layer is disposed between a second surface of the polarizer layer and a first surface of the display layer, and a third adhesive layer is disposed between the second surface of the display layer and a first surface of the support film layer, and configured to adhere the first surface of the window layer to the first surface of the polarizer layer, the second surface of the polarizer layer to the first surface of the display layer, and the second surface of the display layer to the first surface of the support film layer.

[0012] According to one or more embodiments of the present disclosure, an amine-epoxide-based chemistry process is provided that offers innovative features that cannot be replicated by silane chemistry. For example, the amine-epoxide-based chemistry / adhesion mechanism can achieve adhesion levels exceeding 1100 gf / in between the adhesive and the substrate at ambient temperature and pressure. The amine-epoxide approach also addresses key issues associated with silane-based adhesive chemistry, such as self-condensation reactions that affect the mechanical performance of OCAs over time. Additionally, additional embodiments herein disclose the development of polymer resin compositions / blends designed to form polysulfide-based OCAs that exhibit low modulus and outstanding adhesion to a variety of substrates, including, but not limited to, glass, DOP, or PET.

[0013] In one embodiment, an optically clear adhesive (OCA) is provided, comprising a polymer resin composition adapted for incorporation into flexible display technologies / materials. The adhesive composition utilizes specific multifunctional monomers and additives designed to improve the stability and performance of conventional OCAs. The polymer resin composition comprises 30-60 wt% thiol monomer, 20-60 wt% at least one vinyl or allyl monomer, and 10-30 wt% difunctional aliphatic urethane oligomer. The polymer resin composition further comprises 1-3 wt% hydrolysis stabilizer additive, 1-5 wt% glycidyl monomer having at least one allyl or acrylate functional group, 0.1-1 wt% cyclic azasilane monomer, 0.5-2 wt% photoinitiator, and 0.01-0.03 wt% wetting agent.

[0014] In flexible display technology applications, the polymer resin composition is cured into an adhesive film with outstanding mechanical performance, the polymer resin composition having a strength of substantially 4 J / cm at temperatures between room temperature and 80°C. 2The film is cured using UVA light at 1000 W / m. The fully cured film exhibits a low modulus, with a first storage modulus of 0.05 to 0.2 MPa at -20°C and a second storage modulus of 0.015 to 0.15 MPa at 60°C, measured in a 1.0 Hz shear mode at a temperature ramp rate of 5°C / min. The film also exhibits excellent optical properties, including a haze of less than 1%, a yellowing index of less than 1, and a light transmittance of up to 94% in the wavelength range of 400 nm to 700 nm. Furthermore, the film maintains its optical and thermomechanical properties even when stored in a high humidity (90%) and high temperature (65°C) environment for up to 240 hours.

[0015] Thiol monomers are a major component of the OCA polymer resin composition. In certain embodiments, the thiol monomers contain two functional groups (difunctional) or three functional groups (trifunctional). For reference herein, "difunctional" monomers are intended to include species containing two thiolic unsaturated sites. Similarly, "trifunctional" monomers are intended to include species containing three thiolic unsaturated sites. Examples of usable difunctional thiols include, but are not limited to, 1,4-bis(3-mercaptobutyroyloxy)butane, ethylene glycol bis-mercaptoacetate, ethylene bis(3-mercaptopropionate), 2,2'-(ethylenedioxy)diethanethiol, or 1,10-decanedithiol. In one embodiment, 1,4-bis(3-mercaptobutyroyloxy)butane or ethylene bis(3-mercaptopropionate) are included. Examples of suitable trifunctional thiols include, but are not limited to, trimethylolpropane tris(3-mercaptopropionate) or tris[2-(3-mercaptopropionyloxy)ethyl]isocyanurate. In one embodiment, tris[2-(3-mercaptopropionyloxy)ethyl]isocyanurate.

[0016] Vinyl and / or allylic monomers are other major components of the OCA polymer resin composition. In certain embodiments, either the vinyl or allylic monomer contains two functional groups (difunctional) or three functional groups (trifunctional). This concept can be understood by reference to the preceding paragraph. Examples of usable difunctional allylic monomers include, but are not limited to, diallyl isophthalate, trimethylolpropane diallyl ether, or triethylene glycol divinyl ether. In one embodiment, the species includes triethylene glycol divinyl ether. Examples of usable trifunctional allylic monomers include, but are not limited to, 1,3,5-triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione or pentaerythritol triallyl ether. In one embodiment, the species includes 1,3,5-triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione.

[0017] Difunctional aliphatic urethane oligomers are another major component of the polymer resin composition of the OCA. Examples of suitable difunctional aliphatic urethane oligomers include, but are not limited to, diallyltrimethylhexamethylenediurethane.

[0018] It is noted that in embodiments, the disclosed method is useful for obtaining OCAs that achieve adhesion strengths of greater than 1100 gf / in. to glass substrates without the need for pre-treatment of the substrate surface. To achieve such adhesion levels, the OCAs are laminated to the substrate surface after aging for no more than 12 hours.

[0019] FIG. 1 is a cross-sectional view of an optical laminate 1 according to a specific embodiment of the present disclosure. As shown, the optical laminate 1 includes an adhesive layer 6 containing an OCA, which is disposed between and in contact with a first surface of a first substrate layer 2 and a second surface of a second substrate layer 4. The adhesive layer 6 may be in direct contact with the first surface of the first substrate layer 2 and the second surface of the second substrate layer 4. In other embodiments, the adhesive layer 6 may be in indirect contact with one or more additional layers (not shown) disposed between the adhesive layer 6 and the first surface of the first substrate layer 2 and the second surface of the second substrate layer 4. The additional layers include, but are not limited to, a hard coat layer, a primer layer, a polarizing layer, a light-emitting layer, or a color filter layer. It is further noted that the adhesive layer 6 may be any embodiment of an OCA disclosed herein.

[0020] 2 is a cross-sectional view of a flexible display 200 according to a specific embodiment of the present disclosure. As shown, the flexible display 200 includes multiple layers commonly associated with flexible displays, including a window layer 202, a polarizer layer 204, a display layer 208, and a support film layer 210. An adhesive layer 206 containing an OCA is disposed between each layer pair (202 / 204, 204 / 208, and 208 / 210). More specifically, one adhesive layer 206 of the multiple adhesive layers 206 is disposed between and in contact with a first surface of the window layer 202 and a first surface of the polarizer layer 204, another adhesive layer 206 is disposed between and in contact with a second surface of the polarizer layer 204 and a first surface of the display layer 208, and yet another adhesive layer 206 is disposed between and in contact with a second surface of the display layer 208 and a first surface of the support film layer 210.

[0021] In other embodiments, adhesive layer 206 is in indirect contact with the first surface of window layer 202, the first surface of polarizer layer 204, the second surface of polarizer layer 204, the first surface of display layer 208, the second surface of the display layer, and the first surface of support film layer 210. In this case, one or more additional layers (not shown) are disposed between adhesive layer 206 and the above-mentioned surfaces. Additional layers include, but are not limited to, a hard coat layer, a primer layer, a polarizing layer, a light-emitting layer, or a color filter layer. It is further noted that adhesive layer 206 may be any embodiment of an OCA disclosed herein. Furthermore, those skilled in the art will understand and appreciate that embodiments of flexible display 200 may include additional layers used in flexible displays and separated by additional adhesive layer 206.

[0022] According to one embodiment of the present disclosure, a method for improving the adhesion of OCA to a substrate is carried out using the steps shown in Reaction Scheme 1 below.

[0023] [ka]

[0024] In one embodiment, a method for improving the adhesive properties of an OCA to a substrate through a tandem ring-opening mechanism using a photopolymerizable glycidyl monomer and a cyclic azasilane monomer is disclosed. The adhesive process, shown in Scheme 1, involves placing a cyclic azasilane monomer near the substrate surface, where the cyclic azasilane monomer binds to hydroxy groups on the substrate surface through a ring-opening reaction initiated by the substrate surface. After the first ring-opening reaction, a second ring-opening reaction occurs, in which the epoxy functional group of the photopolymerizable glycidyl monomer located on the OCA surface is opened by interaction with the reacted (opened) cyclic azasilane monomer (the ring-opening mechanism occurs in the photopolymerizable glycidyl monomer). As a result of these two ring-opening reactions, a covalent bond is formed between the OCA and the substrate at the interface between the OCA and the substrate. Furthermore, the reacted OCA exhibits excellent mechanical stability and optical properties, making it useful for flexible display applications. In embodiments, the process includes a glycidyl monomer having at least one of the following: one or more photopolymerizable allyl groups, one or more photopolymerizable acrylate groups, one or more photopolymerizable vinyl groups, or one or more photopolymerizable thiol groups.

[0025] In embodiments, the process includes a first ratio of glycidyl monomer to cyclic azasilane monomer of 1%:0.5% by weight. This ratio contributes to improved adhesion of the OCA to the substrate without pre-treatment of the substrate. Additionally, this ratio promotes adhesion of greater than 1100 gf / in (without pre-treatment). To achieve this adhesion, the OCA is aged for no more than 12 hours before being laminated to the substrate surface. For storage for extended periods of more than 12 hours, the glycidyl monomer and cyclic azasilane monomer are stored under an inert atmosphere, and guidelines for safe handling and storage procedures are provided to those handling these monomers. In additional embodiments, the process includes a second ratio of glycidyl monomer to cyclic azasilane monomer of 2:1.

[0026] One or more embodiments of the present disclosure provide materials for building flexible display technologies that have higher quality and performance compared to other flexible display technologies.

[0027] The optically clear adhesives (OCA) / polymer resins disclosed herein can be used in flexible or non-flexible displays / display devices / display panels. The optically clear adhesives (OCA) / polymer resins are incorporated into one or more layers of the display / display device / display panel, including, but not limited to, a sealing layer, a cathode layer, a light-emitting layer, an adhesive layer, a conductive layer, an anode layer, a substrate layer, and any layers mentioned in connection with FIG. 2. It should be understood that the display / display device / display panel may include additional film layers not mentioned herein.

[0028] In one embodiment of the present disclosure, an electronic device is provided, and one or more optically clear adhesives (OCAs) / polymer resins of the present disclosure are used in the display / display device / display panel of the electronic device. For example, the electronic device may be a smartphone, a mobile phone, a video phone, a camera, a wearable device (e.g., electronic clothing, electronic accessories, smart watches, head-worn devices, electronic bracelets, electronic necklaces, electronic tattoos), a personal digital assistant (PDA), a desktop computer (PC), a laptop PC, a netbook PC, a portable multimedia player (PMP), a digital audio player, a portable medical device, an e-reader, or the like. In an additional embodiment, the electronic device is a smart home appliance including a display / display device / display panel. For example, the smart home appliance may be an electronic key, a stereo, a television, a set-top box, a TV box, a video recorder, a game console, a vacuum cleaner, a digital video disc (DVD) player, a refrigerator, an air conditioner, an oven, a dryer, an air purifier, a microwave oven, a washing machine, an electronic dictionary, an electronic photo frame, or the like.

[0029] The exemplary systems, methods, and operations described in the above embodiments are illustrative, and in other embodiments, certain operations may be performed in a different order, in parallel with one another, omitted entirely, or combined between different exemplary embodiments, and certain additional operations may be performed, without departing from the scope and spirit of each embodiment. Accordingly, such other embodiments are also included in the description herein.

[0030] As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms unless the context clearly indicates otherwise. It will be further understood that, as used herein, the terms "comprises" and / or "comprising" identify the presence of stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. As used herein, phrases such as "between X and Y" and "between about X and Y" should be interpreted to include X and Y. A phrase such as "between about X and Y" means "between about X and about Y." As used herein, expressions such as "from about X to Y" mean "from about X to about Y."

[0031] The above-disclosed embodiments are presented as examples to enable those skilled in the art to practice the disclosure, and are not intended to limit or be exhaustive. Numerous minor modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the disclosure. The claims are intended to broadly encompass the disclosed embodiments and such modifications. Furthermore, the following aspects represent other embodiments of the present disclosure and should be included within the scope of the present disclosure.

[0032] Aspect 1. An optically clear adhesive (OCA), a polymer resin composition, the polymer resin composition comprising: 30 to 60 wt. % of a thiol monomer; 20 to 60% by weight of at least one vinyl or allyl monomer; and 10 to 30 wt % of a difunctional aliphatic urethane oligomer; 1. An optically clear adhesive comprising:

[0033] Aspect 2. 2. The optically clear adhesive of claim 1, wherein the polymer resin composition comprises: 1 to 3 wt. % of a hydrolysis stabilizer additive; 1 to 5 wt. % of a glycidyl monomer having at least one allyl or acrylate functional group; 0.1 to 1% by weight of a cyclic azasilane monomer; 0.5 to 2 wt. % of a photoinitiator, and 0.01 to 0.03 wt. % of a wetting agent; 10. The optically clear adhesive, further comprising:

[0034] Aspect 3. 2. The optically clear adhesive of embodiment 1, wherein the polymer resin composition is cured into a film.

[0035] Aspect 4. 4. The optically clear adhesive of claim 3, wherein the polymer resin composition has a viscosity of substantially 4 J / cm 2 An optically clear adhesive is cured to the film using UVA light having an intensity of 1000 .mu.m at a temperature between room temperature and 80.degree.

[0036] Aspect 5. 10. The optically transparent adhesive of claim 3, wherein the film is fully cured, and the film has a first storage modulus of 0.05 to 0.2 MPa at −20° C. and a second storage modulus of 0.015 to 0.15 MPa at 60° C.

[0037] Aspect 6. 2. The optically clear adhesive of claim 1, wherein the thiol monomer comprises two or three functional groups.

[0038] Aspect 7. 2. The optically clear adhesive of claim 1, wherein at least one of the vinyl or allylic monomers comprises a functional group of 2 or 3.

[0039] Aspect 8. 4. The optically clear adhesive of embodiment 3, wherein the film comprises less than 1% haze.

[0040] Aspect 9. 4. The optically clear adhesive of embodiment 3, wherein the film comprises a yellowing index of less than 1.

[0041] Aspect 10. 4. The optically transparent adhesive according to claim 3, wherein the film has a light transmittance of up to 94% in the wavelength range of 400 nm to 700 nm.

[0042] Aspect 11. 4. The optically clear adhesive of claim 3, wherein the film comprises an adhesion strength of greater than 1100 gf / inch to a glass substrate, and further wherein the glass substrate has not been pretreated.

[0043] Aspect 12. An optical laminate, a first substrate layer having a first surface; a second substrate layer having a second surface; and an adhesive layer; Including, the adhesive layer comprises an optically clear adhesive (OCA); the optically clear adhesive comprises a polymer resin composition; The polymer resin composition comprises: 30 to 60 wt. % of a thiol monomer; 20 to 60% by weight of at least one vinyl or allyl monomer; and 10 to 30 wt % of a difunctional aliphatic urethane oligomer; Including, an adhesive layer disposed between a first surface of the first substrate layer and a second surface of the second substrate layer, and adhering the first surface of the first substrate layer to the second surface of the second substrate layer;

[0044] Aspect 13. 13. The optical laminate of claim 12, wherein the polymer resin composition comprises: 1 to 3 wt. % of a hydrolysis stabilizer additive; 1 to 5 wt. % of a glycidyl monomer having at least one allyl or acrylate functional group; 0.1 to 1% by weight of a cyclic azasilane monomer; 0.5 to 2 wt. % of a photoinitiator, and 0.01 to 0.03 wt. % of a wetting agent; The optical laminate further comprises:

[0045] Aspect 14. A method for improving the adhesive strength of an optically clear adhesive (OCA) to a substrate, comprising carrying out the steps shown in Reaction Scheme 1 below. TIFF2025160139000003.tif86141

[0046] Aspect 15. 15. The method of embodiment 14, wherein the step is performed on a substrate that has not been pretreated.

[0047] Aspect 16. 15. The method of embodiment 14, wherein the substrate comprises glass.

[0048] Aspect 17. 15. The method of embodiment 14, wherein the step comprises providing a glycidyl monomer having at least one of the following: one or more photopolymerizable allyl groups, one or more photopolymerizable acrylate groups, one or more photopolymerizable vinyl groups, or one or more photopolymerizable thiol groups.

[0049] Aspect 18. 15. The method of embodiment 14, wherein the step comprises a 2:1 ratio of glycidyl monomers to cyclic azasilane monomers.

[0050] Aspect 19. 15. The method of embodiment 14, wherein the step comprises a ratio of glycidyl monomer to cyclic azasilane monomer of 1%:0.5% by weight.

[0051] Aspect 20. 20. The method of embodiment 19, wherein the ratio of the glycidyl monomer to the cyclic azasilane monomer promotes adhesion of the optically clear adhesive (OCA) to a substrate of greater than 1100 gf / inch.

[0052] Aspect 21. 15. The method of embodiment 14, wherein the step comprises a tandem ring-opening mechanism.

[0053] Aspect 22. A flexible display, a window layer; a polarizer layer; and a display layer; and a support film layer; and a plurality of adhesive layers; Including, each of the plurality of adhesive layers comprises an optically clear adhesive (OCA); the optically clear adhesive comprises a polymer resin composition; The polymer resin composition comprises: 30 to 60 wt. % of a thiol monomer; 20 to 60% by weight of at least one vinyl or allyl monomer; and 10 to 30 wt % of a difunctional aliphatic urethane oligomer; Including, A flexible display, wherein a first adhesive layer of the plurality of adhesive layers is disposed between the first surface of the window layer and the first surface of the polarizer layer, a second adhesive layer is disposed between the second surface of the polarizer layer and the first surface of the display layer, and a third adhesive layer is disposed between the second surface of the display layer and the first surface of the support film layer, bonding the first surface of the window layer to the first surface of the polarizer layer, the second surface of the polarizer layer to the first surface of the display layer, and the second surface of the display layer to the first surface of the support film layer.

[0054] Aspect 23. 23. The flexible display of claim 22, wherein the polymer resin composition comprises: 1 to 3 wt. % of a hydrolysis stabilizer additive; 1 to 5 wt. % of a glycidyl monomer having at least one allyl or acrylate functional group; 0.1 to 1% by weight of a cyclic azasilane monomer; 0.5 to 2 wt. % of a photoinitiator, and 0.01 to 0.03 wt. % of a wetting agent; The flexible display further includes:

Claims

1. An optically clear adhesive (OCA), comprising: a polymer resin composition, the polymer resin composition comprising: 30 to 60 wt. % of a thiol monomer; 20 to 60% by weight of at least one vinyl or allylic monomer; and 10 to 30 wt. % of a difunctional aliphatic urethane oligomer; 1. An optically clear adhesive comprising:

2. 2. The optically clear adhesive of claim 1, wherein the polymer resin composition comprises: 1-3 wt. % of a hydrolysis stabilizer additive; 1 to 5 weight percent of a glycidyl monomer having at least one allyl or acrylate functionality; 0.1 to 1 wt. % of a cyclic azasilane monomer; 0.5 to 2 wt. % of a photoinitiator, and 0.01 to 0.03 wt. % of a wetting agent; 10. The optically clear adhesive, further comprising:

3. 10. The optically clear adhesive of claim 1, wherein the polymer resin composition is cured into a film.

4. 4. The optically clear adhesive of claim 3, wherein the polymer resin composition has a viscosity of substantially 4 J / cm ２ an optically clear adhesive that is cured to the film using UVA light having an intensity of 1000 .ANG. at a temperature between room temperature and 80.degree.

5. 4. The optically clear adhesive of claim 3, wherein the film is fully cured, and the film comprises a first storage modulus of 0.05 to 0.2 MPa at −20° C. and a second storage modulus of 0.015 to 0.15 MPa at 60° C.

6. 10. The optically clear adhesive of claim 1, wherein the thiol monomer comprises two or three functional groups.

7. 10. The optically clear adhesive of claim 1, wherein at least one of the vinyl or allylic monomers contains a functionality of 2 or 3.

8. 4. The optically clear adhesive of claim 3, wherein the film comprises a haze of less than 1%.

9. 4. The optically clear adhesive of claim 3, wherein the film comprises a yellowing index of less than 1.

10. 4. The optically clear adhesive of claim 3, wherein the film comprises a maximum light transmittance of 94% in the wavelength range of 400 nm to 700 nm.

11. 4. The optically clear adhesive of claim 3, wherein the film has an adhesion strength of greater than 1100 gf / inch to a glass substrate, and further wherein the glass substrate is not pretreated.

12. An optical laminate, a first substrate layer having a first surface; a second substrate layer having a second surface; and an adhesive layer; Including, the adhesive layer comprises an optically clear adhesive (OCA); the optically clear adhesive comprises a polymer resin composition; The polymer resin composition comprises: 30 to 60 wt. % of a thiol monomer; 20 to 60% by weight of at least one vinyl or allylic monomer; and 10 to 30 wt. % of a difunctional aliphatic urethane oligomer; Including, an adhesive layer disposed between a first surface of the first substrate layer and a second surface of the second substrate layer, and adhering the first surface of the first substrate layer to the second surface of the second substrate layer;

13. 13. The optical laminate according to claim 12, wherein the polymer resin composition is 1-3 wt. % of a hydrolysis stabilizer additive; 1 to 5 weight percent of a glycidyl monomer having at least one allyl or acrylate functionality; 0.1 to 1 wt. % of a cyclic azasilane monomer; 0.5 to 2 wt. % of a photoinitiator, and 0.01 to 0.03 wt. % of a wetting agent; The optical laminate further comprises:

14. A method for improving the adhesion of an optically clear adhesive (OCA) to a substrate, comprising carrying out the steps shown in Reaction Scheme 1 below.

15. 15. The method of claim 14, wherein the process is performed on a substrate that has not been pretreated.

16. The method of claim 14 , wherein the substrate comprises glass.

17. 15. The method of claim 14, wherein the process includes a glycidyl monomer having at least one of the following: one or more photopolymerizable allyl groups, one or more photopolymerizable acrylate groups, one or more photopolymerizable vinyl groups, or one or more photopolymerizable thiol groups.

18. 15. The method of claim 14, wherein the process comprises a 2:1 ratio of glycidyl monomer to cyclic azasilane monomer.

19. 15. The method of claim 14, wherein the step comprises a ratio of glycidyl monomer to cyclic azasilane monomer of 1% by weight:0.5% by weight.

20. 20. The method of claim 19, wherein the ratio of the glycidyl monomer to the cyclic azasilane monomer promotes adhesion of the optically clear adhesive (OCA) to the substrate to greater than 1100 gf / inch.

21. 15. The method of claim 14, wherein the process comprises a tandem ring-opening mechanism.

22. A flexible display, a window layer; a polarizer layer; and a display layer; and a support film layer; and a plurality of adhesive layers; Including, each of the plurality of adhesive layers comprises an optically clear adhesive (OCA); the optically clear adhesive comprises a polymer resin composition; The polymer resin composition comprises: 30 to 60 wt. % of a thiol monomer; 20 to 60% by weight of at least one vinyl or allylic monomer; and 10 to 30 wt. % of a difunctional aliphatic urethane oligomer; Including, A flexible display, wherein a first adhesive layer of the plurality of adhesive layers is disposed between the first surface of the window layer and the first surface of the polarizer layer, a second adhesive layer is disposed between the second surface of the polarizer layer and the first surface of the display layer, and a third adhesive layer is disposed between the second surface of the display layer and the first surface of the support film layer, bonding the first surface of the window layer to the first surface of the polarizer layer, the second surface of the polarizer layer to the first surface of the display layer, and the second surface of the display layer to the first surface of the support film layer.

23. 23. The flexible display of claim 22, wherein the polymer resin composition comprises: 1-3 wt. % of a hydrolysis stabilizer additive; 1 to 5 weight percent of a glycidyl monomer having at least one allyl or acrylate functionality; 0.1 to 1 wt. % of a cyclic azasilane monomer; 0.5 to 2 wt. % of a photoinitiator, and 0.01 to 0.03 wt. % of a wetting agent; The flexible display further includes:

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