Novel uv-curing adhesive for ar optical waveguide

Abstract

The present disclosure relates to a novel ultraviolet light curing adhesive for AR optical waveguide, comprising the following components: 20-70 parts by weight of acrylate oligomer or acrylate monomer; 20-70 parts by weight of active diluent, which is isooctyl acrylate (IBOA); 1-10 parts by weight of catalyst selected from xylene ketone and its derivatives, hydrogen abstraction type photoinitiator, cleavage type photoinitiator. The ultraviolet light curing adhesive not only has a relatively low pure adhesive viscosity, can meet the demand of relatively thin coating film thickness for AR optical waveguide grating, but also has high refractive index and transmittance, excellent optical and physical and chemical properties, especially, has excellent structure forming property, high structure fidelity, and can reach >94%.

Description

A new type of UV curing adhesive for AR optical waveguide Technical Field

[0001] The present disclosure relates to the fields of chemistry and display technology, and in particular to a novel ultraviolet light-curing adhesive for AR optical waveguides. Background Art

[0002] With the rapid development of virtual reality technologies such as AR / VR driven by the "metaverse fever," optical waveguides have gradually attracted widespread attention and are being widely used in areas such as product advertising, mobile shopping, multi-screen interaction, location navigation, and gaming. Surface relief grating (SRG) diffraction waveguides are considered the most promising mainstream AR waveguide lens fabrication solution due to their ease of mass production and excellent performance.

[0003] In addition to inherent design parameters, SRG diffraction waveguides also place greater demands on structural materials for functionality, including optical properties like refractive index and structural formability like structural fidelity. Consequently, the design and development of a material that combines both optical properties and structural formability is crucial for waveguide applications.

[0004] Summary of the Invention

[0005] In order to solve the above problems, the inventors of the present invention have obtained a new UV-curing adhesive through continuous research and exploration. This UV-curing adhesive not only has a low pure adhesive viscosity, which can meet the requirements of thinner coating thickness for AR optical waveguide gratings, but also has a high refractive index and transmittance, and has excellent optical and physical and chemical properties. In particular, it also has excellent structural formability and high structural fidelity, which can reach >94%.

[0006] To this end, in a first aspect of the present disclosure, the present disclosure provides a UV-curable adhesive comprising the following components:

[0007] 20-70 parts by weight (e.g., 20, 25, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 45, 50, 55, 60, 65, or 70 parts by weight, or such as 20-25, 25-30, 30-31, 31-32, 32-33, 33-34, 34-35, 35-36, 36-37, 37-38, 38-39, 39-40, 40-45, 45-50, 50-55, 55-60, 60-65, or 65-70 parts by weight) of an acrylate oligomer or acrylate monomer (preferably an acrylate monomer);

[0008] 20-70 parts by weight (e.g., 20, 25, 30, 35, 40, 45, 50, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, or 70 parts by weight, or such as 20-25, 25-30, 30-35, 35-40, 40-45, 45-50, 50-55, 55-56, 56-57, 57-58, 58-59, 59-60, 60-61, 61-62, 62-63, 63-64, 64-65, or 65-70 parts by weight) of a reactive diluent, wherein the reactive diluent is isooctyl acrylate (IBOA);

[0009] 1-10 parts by weight (such as 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 parts by weight, or such as 1-2, 2-3, 3-4, 4-5, 5-6, 6-7, 7-8, 8-9 or 9-10 parts by weight) of a catalyst, wherein the catalyst is selected from xylene ketone and its derivatives, a hydrogen abstraction photoinitiator, a cleavage photoinitiator (preferably, the catalyst is selected from a cleavage photoinitiator).

[0010] In some embodiments, the acrylate monomer is selected from one or more acrylate monomers having a functionality of 1 to 6.

[0011] In some embodiments, the acrylic acid ester monomer is selected from 1,6-hexanediol diacrylate monomer (HDDA), 1,6-hexanediol methoxy monoacrylate monomer (EOTMPTA), neopentyl glycol diacrylate monomer (NPGDA), propoxylated neopentyl glycol diacrylate monomer (PONPGDA), tripropylene glycol diacrylate monomer (TPGDA), dipropylene glycol diacrylate monomer (DPGDA), 2-phenoxyethyl acrylate monomer (PHEA), ethoxylated phenoxy acrylate monomer (PH3EOA), tetrahydrofurfuryl acrylate monomer (THFA), isopropyl acrylate monomer (ISO-1,2-DIMETHYL HYDROX ... One or more of bornyl acrylate monomer (IBOA), benzyl acrylate monomer (BA), 4-tert-butylcyclohexyl acrylate monomer (TBCHA), trimethylolpropane triacrylate (TMPTA), ethoxylated trimethylolpropane triacrylate (EOTMPTA), propoxylated trimethylolpropane triacrylate (POTMPTA), pentaerythritol triacrylate (PET3A), pentaerythritol tetraacrylate (PET4A), di(trimethylolpropane) tetraacrylate, dipentaerythritol hexaacrylate (DPHA), and caprolactone-modified dipentaerythritol hexaacrylate.

[0012] In some embodiments, the acrylic acid ester monomer is 1,6-hexanediol diacrylate monomer (HDDA).

[0013] In some embodiments, the acrylate oligomer is selected from aliphatic urethane acrylate, aromatic urethane acrylate, epoxy acrylate, and polyester acrylate.

[0014] In some embodiments, the weight ratio of the acrylic ester oligomer or acrylic ester monomer is 30-40 (preferably 35).

[0015] In some embodiments, the cleavage-type photoinitiator is acylphosphine oxide (TPO), 1-hydroxycyclohexylbenzophenone, and the like.

[0016] In some embodiments, the cleavage-type photoinitiator is 1-hydroxycyclohexyl benzophenone.

[0017] In some embodiments, the hydrogen abstraction type photoinitiator is a thioxanthone compound.

[0018] In some embodiments, the weight portion of the catalyst is 1-3 (preferably 1).

[0019] In some embodiments, the weight percentage of the reactive diluent is 55-65 (preferably 60).

[0020] In some embodiments, the UV-curable adhesive further comprises an auxiliary agent.

[0021] In some embodiments, the auxiliary agent is selected from a tackifier, a leveling agent, a defoaming agent, or any combination thereof.

[0022] In some embodiments, the viscosity increasing agent is selected from lipids such as diethyl succinate, and silicone compounds such as 3-glycidyloxypropyltrimethoxysilane.

[0023] In some embodiments, the weight portion of the auxiliary agent is 1-5 (such as 1, 2, 3, 4 or 5, or such as 1-2, 2-3, 3-4 or 4-5, preferably 4).

[0024] In a second aspect of the present disclosure, the present disclosure provides a method for preparing the UV-curable adhesive according to any technical solution of the first aspect, comprising:

[0025] Mixing the acrylate oligomer or acrylate monomer, the catalyst, and the reactive diluent to obtain the UV-curable adhesive;

[0026] Alternatively, the acrylate oligomer or acrylate monomer, the catalyst, the reactive diluent, and the auxiliary agent are mixed to obtain the UV-curable adhesive.

[0027] In some embodiments, the method comprises:

[0028] performing a first mixing of the acrylate oligomer or acrylate monomer and the catalyst to obtain a first raw material;

[0029] Using the active diluent as a second raw material, or performing a second mixing of the active diluent and the auxiliary agent to obtain a second raw material;

[0030] The first raw material and the second raw material are mixed for a third time to obtain the UV curing adhesive.

[0031] In some embodiments, the method has one or more technical features selected from the following (i)-(vi):

[0032] (i) the first mixing is performed at room temperature;

[0033] (ii) the stirring speed of the first mixing is 500-1500 rpm / min, preferably 1000 rpm / min;

[0034] (iii) the stirring time of the first mixing is 20-40 min, preferably 30 min;

[0035] (iv) the third mixing is performed at room temperature;

[0036] (v) the stirring speed of the third mixing is 2000 rpm / min-4000 rpm / min, preferably 3000 rpm / min;

[0037] (vi) The stirring time of the third mixing is 0.5 h to 1.5 h, preferably 1 h.

[0038] In a third aspect of the present disclosure, the present disclosure provides a diffraction optical waveguide, which includes a substrate and a grating arranged on the substrate, and the grating is formed by the ultraviolet light curing adhesive described in any technical solution of the first aspect.

[0039] In a fourth aspect of the present disclosure, the present disclosure provides an electronic device comprising the diffractive optical waveguide according to the third aspect. Beneficial effects

[0040] 1. The UV-curable adhesive disclosed herein not only has a low pure adhesive viscosity, which can meet the requirement of thinner coating thickness for AR optical waveguide gratings, but also has a high refractive index and transmittance, and has excellent optical and physical and chemical properties.

[0041] 2. The UV curing adhesive disclosed herein also has excellent structural formability and high structural fidelity, which can reach >94%.

[0042] 3. The disclosed UV-curable adhesive exhibits excellent chemical and mechanical properties, including fast curing speed, good light transmittance, and toughness, making it particularly suitable for use in UV nanoimprinting processes. Furthermore, the disclosed preparation method offers low manufacturing costs, a simple process, no need for complex equipment, low energy consumption, and the ability to achieve continuous production. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 shows the light curing mechanism of UV light curing adhesive.

[0044] Figure 2 shows an example of the process for preparing UV-curable adhesive.

[0045] FIG3 shows the molecular structural formulas: (a) HDDA, (b) IBOA, and (c) 1-hydroxycyclohexylphenyl ketone.

[0046] FIG4 shows a schematic diagram of the glue prepared in the embodiment.

[0047] FIG5 shows the glue property data collection results of the glue prepared in the embodiment.

[0048] Figure 6 shows a schematic diagram of the structural formability test process of UV-curing adhesive in application.

[0049] FIG7 shows a SEM image of the structure of the homemade UV-curable adhesive prepared in Preparation Example 1 on the AR grating.

[0050] Figure 8 shows the data collection results for the comparative glue properties.

[0051] FIG9 shows a physical picture of the 1# formula in the comparative example and a physical picture of the glue after spin coating. DETAILED DESCRIPTION

[0052] The present disclosure is further explained below with reference to specific examples, but is not to be construed as limiting the present disclosure in any way. Unless otherwise specified, all reaction raw materials are commercially available. Unless otherwise specified, all detection or testing methods are well known and mastered by those skilled in the art.

[0053] This disclosure provides a UV-curable adhesive and its preparation method, aiming to address the mismatch between optical properties and formability in UV-curable adhesives. The UV-curable adhesive disclosed herein improves the optical refractive index and transmittance of the material while also achieving superior structural formability.

[0054] Figure 1 shows the curing mechanism of UV-curable adhesive. The desired UV-curable adhesive can be obtained by quantitatively configuring the monomer components as needed. UV irradiation triggers the generation of reactive free radicals from the photoinitiator, which in turn induces the generation of reactive free radicals from the reactive monomers. These radicals then gradually initiate the monomers to link into long chains, ultimately achieving complete curing.

[0055] Duty cycle: grating width / grating period (width / pitch)

[0056] The present disclosure is further explained below with reference to specific embodiments.

[0057] Example: Preparation and testing of UV-curable adhesive

[0058] Preparation Example 1:

[0059] Figure 2 shows an example of the glue preparation process. Specifically, 1,6-hexanediol diacrylate (HDDA) is selected as the acrylate monomer (molecular formula shown in Figure 3(a)) and added to the reaction vessel in an amount of 35 parts by weight. Then, a photoinitiator, 1-hydroxycyclohexyl phenyl ketone (molecular formula shown in Figure 3(c)), is added in an amount of 1 part by weight. Then, a magnetic stirrer is used at room temperature at 1000 rpm / min for 30 minutes to obtain the first raw material shown in Figure 2. Then, isooctyl acrylate (IBOA) is selected as the reactive diluent (molecular formula shown in Figure 3(b)) in an amount of 60 parts by weight as the second raw material shown in Figure 2. Finally, the first and second raw materials are thoroughly mixed and stirred at 3000 rpm / min for 1 hour to obtain the final 1# UV-curable adhesive.

[0060] Preparation Example 2-5:

[0061] Except that the weight of the reactive diluent isooctyl acrylate (IBOA) in Preparation Example 1 was adjusted, the rest of the preparation process was exactly the same as that in Preparation Example 1.

[0062] Figure 4 shows a photo of the glue obtained by adjusting the above formulations in this example. Data was collected on the physical and chemical properties, optical properties, and light-curing properties of the above light-curing glues, with the results shown in Figure 5. Viscosity was measured using a rotational viscometer, transmittance using a UV spectrophotometer, haze using a haze meter, refractive index using an ellipsometer, and light-curing energy calculated based on the curing equipment.

[0063] It can be seen from the experimental results that the light-curing glue of this embodiment exhibits a low pure glue viscosity, which can meet the requirement of a thinner coating thickness for AR optical waveguide gratings, and has a high refractive index and transmittance, and has excellent optical and physical and chemical properties.

[0064] From the above experimental results, it can be seen that the UV-curable adhesive disclosed in the present invention not only has a low pure adhesive viscosity, which can meet the requirement of thinner coating thickness for AR optical waveguide gratings, but also has a high refractive index and transmittance, and has excellent optical and physical and chemical properties.

[0065] Test example: Structural formability test of UV-curing adhesive

[0066] The structural formability of the photocurable glue prepared in the above embodiment is tested and confirmed. First, as shown in Figure 6, the structural imprinting characteristics are verified by the nanoimprinting process. First, a film layer of photoresist is deposited on a glass substrate by spin coating or the like, and the master template is preferably prepared by, but not limited to, EBL electron beam gradient exposure etching and development. The prepared grating period is preferably, but not limited to, 200-800nm, the grating duty cycle is preferably, but not limited to, 0.1-0.9, and the grating height is preferably, but not limited to, 200-600nm. The height of the rectangular grating part of the prepared master template is greater than or equal to 10nm, and the grating period and duty cycle are consistent with the blazed grating. Then, nanoimprinting is performed to transfer the master template shape to the soft template to form a mother template. Then, the homemade UV-curable glue of the above embodiment (such as the photocurable glue obtained in Preparation Example 1) is applied to the white glass, preferably, but not limited to, spin coating, and the structural imprint is performed by, preferably, but not limited to, nanoimprinting, followed by UV curing and demolding. The imprinting result is shown in Figure 7.

[0067] The size (height and width) of the product's nanostructure is measured using a scanning electron microscope (SEM) or an atomic force microscope (AFM), and compared with the size (height and width) of the master template to obtain the corresponding structural fidelity.

[0068] After testing, the embossed products obtained by the UV-curable adhesive of the above embodiment (such as Preparation Example 1) can achieve structural formability of tens to hundreds of nanometers, and the structural fidelity can reach >94%, which is better than the embossing results of commercially available structural adhesives.

[0069] From the above test results, it can be seen that the UV curing adhesive disclosed in the present invention has excellent structural formability and high structural fidelity, which can reach >94%.

[0070] Comparative Example

[0071] The preparation process of the UV-curable adhesive is basically the same as that of Preparation Example 1 in the above embodiment, except that the reactive diluent IBOA is replaced by 3-phenoxybenzyl acrylate (PBA) in equal amounts.

[0072] The testing methods for the physicochemical properties, optical properties and light-curing properties of the light-curing glue are the same as those in the above embodiment, and the test results are shown in Figure 8.

[0073] The structure forming test method is exactly the same as the above test example, and the results are shown in Figure 9. Due to the poor film forming properties and interface properties of the prepared glue, micro-nanostructure imprinting was impossible, and severe peeling problems occurred after imprinting and demolding.

[0074] While specific embodiments of the present disclosure have been described above, those skilled in the art will appreciate that these are merely illustrative and that the scope of protection of the present disclosure is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present disclosure, and such changes and modifications are intended to fall within the scope of protection of the present disclosure.

Claims

1. UV curing adhesive, which contains the following components: 20-70 parts by weight of acrylate oligomer or acrylate monomer; 20-70 parts by weight of a reactive diluent, wherein the reactive diluent is isooctyl acrylate (IBOA); 1-10 parts by weight of a catalyst, wherein the catalyst is selected from xylene ketone and its derivatives, a hydrogen abstraction type photoinitiator, and a cracking type photoinitiator.

2. The UV curing adhesive according to claim 1, wherein: The acrylic acid ester monomer is selected from one or more acrylic acid ester monomers having a functionality of 1-6.

3. The UV curing adhesive according to any one of claims 1 to 2, wherein: The acrylate monomer is selected from 1,6-hexanediol diacrylate monomer (HDDA), 1,6-hexanediol methoxy monoacrylate monomer (EOTMPTA), neopentyl glycol diacrylate monomer (NPGDA), propoxylated neopentyl glycol diacrylate monomer (PONPGDA), tripropylene glycol diacrylate monomer (TPGDA), dipropylene glycol diacrylate monomer (DPGDA), 2-phenoxyethyl acrylate monomer (PHEA), ethoxylated phenoxy acrylate monomer (PH3EOA), tetrahydrofurfuryl acrylate monomer (THFA), isobornyl acrylate monomer (BPA ... One or more of olefin ester monomer (IBOA), benzyl acrylate monomer (BA), 4-tert-butylcyclohexyl acrylate monomer (TBCHA), trimethylolpropane triacrylate (TMPTA), ethoxylated trimethylolpropane triacrylate (EOTMPTA), propoxylated trimethylolpropane triacrylate (POTMPTA), pentaerythritol triacrylate (PET3A), pentaerythritol tetraacrylate (PET4A), di(trimethylolpropane) tetraacrylate, dipentaerythritol hexaacrylate (DPHA), and caprolactone-modified dipentaerythritol hexaacrylate.

4. The UV curing adhesive according to any one of claims 1 to 3, wherein: The acrylic acid ester monomer is 1,6-hexanediol diacrylate monomer (HDDA).

5. The UV curing adhesive according to claim 1, wherein: The acrylate oligomer is selected from aliphatic polyurethane acrylate, aromatic polyurethane acrylate, epoxy acrylate, and polyester acrylate.

6. The UV curing adhesive according to any one of claims 1 to 5, wherein: The weight proportion of the acrylic ester oligomer or acrylic ester monomer is 30-40 parts.

7. The UV curing adhesive according to any one of claims 1 to 6, wherein: The cleavage-type photoinitiator is acylphosphine oxide (TPO), 1-hydroxycyclohexyl benzophenone and the like.

8. The UV curing adhesive according to any one of claims 1 to 7, wherein: The cleavage-type photoinitiator is 1-hydroxycyclohexyl benzophenone.

9. The UV curing adhesive according to claim 1, wherein: The hydrogen abstraction type photoinitiator is a thioxanthone compound.

10. The UV curing adhesive according to any one of claims 1 to 9, wherein: The weight portion of the catalyst is 1-3.

11. The UV curing adhesive according to any one of claims 1 to 10, wherein: The weight portion of the active diluent is 55-65.

12. The UV curing adhesive according to any one of claims 1 to 11, wherein: The UV curing adhesive further comprises an auxiliary agent; Preferably, the auxiliary agent is selected from a tackifier, a leveling agent, a defoamer or any combination thereof; Preferably, the viscosity enhancer is selected from lipids such as diethyl succinate, and siloxane compounds such as 3-glycidyloxypropyltrimethoxysilane; Preferably, the weight portion of the auxiliary agent is 1-5.

13. A method for preparing the UV-curable adhesive according to any one of claims 1 to 12, comprising: Mixing the acrylate oligomer or acrylate monomer, the catalyst, and the reactive diluent to obtain the UV-curable adhesive; Alternatively, the acrylate oligomer or acrylate monomer, the catalyst, the reactive diluent, and the auxiliary agent are mixed to obtain the UV-curable adhesive.

14. The method according to claim 13, wherein The method comprises: performing a first mixing of the acrylate oligomer or acrylate monomer and the catalyst to obtain a first raw material; Using the active diluent as a second raw material, or performing a second mixing of the active diluent and the auxiliary agent to obtain a second raw material; The first raw material and the second raw material are mixed for a third time to obtain the UV curing adhesive.

15. A diffraction optical waveguide comprising a substrate and a grating disposed on the substrate, wherein the grating is formed by the ultraviolet curing adhesive according to any one of claims 1 to 12.

16. An electronic device comprising the diffractive optical waveguide according to claim 15.

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