Urethane acrylic resin, photocurable composition and waveguide product

Abstract

The invention provides polyurethane acrylic resin, a photocuring composition and a waveguide product, and preparation raw materials of the polyurethane acrylic resin comprise a prepolymer and an end-capping reagent; the prepolymer contains a structure as shown in the following formula I: Linker is a residue of ternary thiol, R1 is a residue of diisocyanate, R2 is a residue of binary thiol, and n is an integer greater than or equal to 1; the end-capping reagent comprises acrylic ester containing hydroxyl and nanoparticles dispersed in the acrylic ester containing hydroxyl; the refractive index of the nanoparticles is greater than or equal to 2.0; the molar ratio of the reactive NCO in the prepolymer to the hydroxyl-containing acrylate in the end-capping reagent is 1: (1-1.2). The main chain of the polyurethane acrylic resin provided by the embodiment of the invention is provided with the thiocarbamate block with high sulfur content, and the end-capping group is provided with the nanoparticles with high refractive index and the photocurable acrylate group, so that the polyurethane acrylic resin has photocuring activity, and meanwhile, the refractive index of a product prepared from the polyurethane acrylic resin can be improved.

Description

Technical Field

[0001] This disclosure relates to the field of optical materials, and more specifically, to a polyurethane acrylic resin, a photocurable composition, and a waveguide article. Background Technology

[0002] Waveguides are optical devices made from specific materials used to guide the transmission of light waves. They have significant applications in augmented reality (AR), virtual reality (VR), optical communication, integrated photonics, and optical sensors. Currently, waveguide manufacturing primarily uses two categories of materials: glass and optical plastics. These two types of materials each have unique characteristics in terms of optical properties and processing characteristics, but they also face significant technological bottlenecks.

[0003] (1) Although glass materials have good optical stability and high refractive index, their high material density restricts the development of lightweight devices and makes it difficult to meet the weight-sensitive application requirements of wearable devices.

[0004] (2) Optical plastics have good processability and lightweight properties, but the heat generated during processing can easily cause material deformation, affecting the subsequent processing accuracy; and the inherent refractive index of optical plastics is generally low, which limits the field of view (FOV) of the waveguide products manufactured, resulting in poor performance in application scenarios such as AR / VR with strict market requirements.

[0005] These limitations in material properties have, to some extent, restricted the application and expansion of waveguide products in high-end optical systems. Summary of the Invention

[0006] This disclosure provides at least one polyurethane acrylic resin, a photocurable composition, and a waveguide article.

[0007] In a first aspect, embodiments of this disclosure provide a polyurethane acrylic resin, wherein the raw materials for preparing the polyurethane acrylic resin include a prepolymer and a capping agent;

[0008] The prepolymer contains the structure shown in Formula I:

[0009]

[0010] Wherein, Linker is the residue after the reaction of trithiol with NCO, R1 is the residue after the reaction of diisocyanate with SH, R2 is the residue after the reaction of dithiol with NCO, and n is an integer ≥1;

[0011] The capping agent comprises a hydroxyl-containing acrylate and nanoparticles dispersed in the hydroxyl-containing acrylate; the refractive index of the nanoparticles is ≥2.0;

[0012] The molar ratio of reactive NCO in the prepolymer to hydroxyl-containing acrylate in the capping agent is 1:(1-1.2).

[0013] In one optional implementation, the Linker has the following structure:

[0014]

[0015] Where a is an integer ≥ 1, b is an integer ≥ 0, c is an integer ≥ 1, d is an integer ≥ 1, and e is an integer ≥ 0.

[0016] In one alternative implementation, the Linker is selected from at least one of the following structures:

[0017]

[0018] In one alternative implementation, R1 is selected from at least one of the following structures:

[0019]

[0020] In one alternative implementation, R2 is selected from at least one of the following structures:

[0021]

[0022] In one optional embodiment, the hydroxyl-containing acrylate includes at least one of hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate, and hydroxyethyl acrylate.

[0023] In one optional embodiment, the nanoparticles include at least one selected from ZrO2, TiO2, ZnO, and CeO2. Further, the average particle size of the nanoparticles is 10–40 nm.

[0024] In one optional embodiment, the nanoparticles constitute 20% to 50% of the end-capping agent by mass.

[0025] In one optional embodiment, the raw materials for preparing the polyurethane acrylic resin further include a polymerization inhibitor. More specifically, the polymerization inhibitor includes at least one selected from p-hydroxyanisole, methyl hydroquinone, and hydroquinone.

[0026] In one optional embodiment, the raw materials for preparing the prepolymer include isocyanate substances and the trithiol in a molar ratio of (3 to 3.5):1;

[0027] The isocyanate contains the structure shown in Formula II:

[0028]

[0029] In one optional embodiment, the ternary thiol comprises at least one selected from 1,3-propanedithiol-2-thioether ethyl thiol, 2,3-dithio(2-mercapto)-1-propanethiol, 3,6,9-thioundecane-5-(2-thiomercaptobutyl)-1,11-dithiol, 3,6,9,12-thiotetradecane-7-(2-thiomercaptobutyl)-1,14-dithiol, and 3,6,9,12-thiotetradecane-7-(mercaptomethyl)-1,14-dithiol.

[0030] In one optional embodiment, the raw materials for preparing the isocyanate include diisocyanate and dithiol in a molar ratio of (2-2.4):1.

[0031] In one optional embodiment, the diisocyanate includes at least one of isophthalic dimethyl isocyanate, tetramethyl isophthalimide diisocyanate, toluene diisocyanate, and norbornene diisocyanate.

[0032] In one optional embodiment, the dithiol includes at least one selected from dithioethyl sulfide, 1,4-dithiam-2,5-di(methanethiol), 1,4-benzenedimethylthiol, 1,3-propanedithiol, 1,4-butanedithiol, and 2,2'-[1,4-butadiylbis(thio)]bisethylthiol.

[0033] In one optional embodiment, the raw materials for preparing the prepolymer and the raw materials for preparing the isocyanate each independently include a catalyst. Further, the catalyst includes at least one selected from dibutyltin dilaurate, dibutyltin dichloride, stannous octoate, dibutyltin diacetate, bismuth isooctanoate, zinc 2-ethylhexanoate, and zinc neodecanoate.

[0034] This disclosure also provides a method for preparing polyurethane acrylic resin, including the following steps: reacting the prepolymer with a capping agent at 85-95°C until the NCO value is 0.

[0035] In one optional embodiment, the preparation of the prepolymer includes: reacting isocyanate and trithiol at 75-85°C under the action of a first catalyst until the NCO value is X1-2 to X1%, where X1 = [126 / M1 + 3 × (M2 + M3 × 2)] × 100%, M1 is the relative molecular mass of the trithiol, M2 is the relative molecular mass of the dithiol, and M3 is the relative molecular mass of the diisocyanate.

[0036] In one optional embodiment, the preparation of the isocyanate includes: reacting diisocyanate and dithiol at 65-75°C under the action of a second catalyst until the NCO value is X2-2 to X2%, where X2 = (84 / M2 + M3×2)×100%, M2 is the relative molecular mass of the dithiol, and M3 is the relative molecular mass of the diisocyanate.

[0037] In a second aspect, embodiments of this disclosure also provide a photocurable composition comprising the following components in parts by weight: 70-80 parts of polyurethane acrylic resin, 20-30 parts of acrylate monomers and 2-5 parts of photoinitiator;

[0038] The polyurethane acrylic resin is any one of the polyurethane acrylic resins provided in the first aspect of this disclosure.

[0039] In one optional embodiment, the acrylate monomer includes at least one of tricyclodecanediethanol diacrylate and tricyclodecanediethanol dimethyl diacrylate.

[0040] Thirdly, embodiments of this disclosure also provide waveguide articles, which are mainly made of any of the photocurable compositions described in the second aspect.

[0041] In one optional embodiment, the density of the waveguide product is 1.25–1.35 g / cm³. 3 The waveguide product has a transmittance of ≥82% at 520nm and a refractive index of >1.64 at 520nm.

[0042] The polyurethane acrylate resin, photocurable composition, and waveguide product provided in this disclosure have a main chain of high-sulfur thiocarbamate blocks, end groups consisting of high-refractive-index nanoparticles and photocurable acrylate groups. Through structural and elemental control, the polyurethane acrylate resin achieves a high refractive index of 1.64 or higher, approximately 1.25–1.35 g / cm³. 3 It has a low density and photocurable reactivity.

[0043] Furthermore, the polyurethane acrylic resin provided in this embodiment improves the material's impact resistance while ensuring its light transmittance and thus enhancing the product's performance by adjusting the specific structure of the thiocarbamate blocks.

[0044] To make the above-described objects, features and advantages of this disclosure more apparent and understandable, preferred embodiments are described in detail below. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions in the embodiments of this disclosure are described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. The components of the embodiments of this disclosure described and shown herein can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this disclosure is not intended to limit the scope of the claimed disclosure, but merely represents selected embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without inventive effort are within the scope of protection of this disclosure.

[0046] The term "and / or" as used in this article describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship.

[0047] This disclosure provides a polyurethane acrylic resin with a main chain containing thiocarbamate blocks with high sulfur content, and end groups consisting of high-refractive-index nanoparticles and photocurable acrylate groups. Through structural and elemental control, the polyurethane acrylic resin achieves a high refractive index of over 1.64, approximately 1.25–1.35 g / cm³. 3 It has a low density and photocurable reactivity.

[0048] The raw materials for preparing the polyurethane acrylic resin provided in this embodiment include prepolymer and end-capping agent;

[0049] The prepolymer contains the structure shown in Formula I:

[0050]

[0051] Wherein, Linker is the residue after the reaction of trithiol with NCO, R1 is the residue after the reaction of diisocyanate with SH, R2 is the residue after the reaction of dithiol with NCO, and n is an integer ≥1;

[0052] The capping agent comprises hydroxyl-containing acrylates and nanoparticles dispersed in the hydroxyl-containing acrylates; the refractive index of the nanoparticles is ≥2.0;

[0053] The molar ratio of reactive NCO in the prepolymer to hydroxyl-containing acrylate in the capping agent is 1:(1~1.2).

[0054] Linker refers to the residue remaining after the reaction of trithiols with NCO, specifically the portion remaining after removing the SH group from the trithiols that participated in the reaction; R1 refers to the residue remaining after the reaction of diisocyanates with SH, specifically the portion remaining after removing the NCO group from the diisocyanates that participated in the reaction; R2 refers to the residue remaining after the reaction of dithiols with NCO, specifically the portion remaining after removing the SH group from the dithiols that participated in the reaction.

[0055] The hydroxyl-containing acrylate in the capping agent introduces double bonds of acrylate into the resin through the reaction of hydroxyl groups with NCO in the prepolymer, giving the resin photocurable properties. At the same time, the nanoparticles dispersed in the hydroxyl-containing acrylate can be embedded in the polymer network during the capping reaction between the hydroxyl-containing acrylate and the prepolymer, thereby increasing the resin refractive index. In addition, the nanoparticles can be uniformly dispersed under the action of the hydroxyl-containing acrylate, improving the light transmittance of the resin.

[0056] In different embodiments, the refractive index of the nanoparticles can be a range of 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, or any combination thereof.

[0057] In different embodiments, the molar ratio of reactive NCO in the prepolymer to hydroxyl-containing acrylate in the capping agent can be a range of 1:1, 1:1.05, 1:1.1, 1:1.15, 1:1.2, or any two of these.

[0058] In some implementations, the Linker has the following structure:

[0059]

[0060] Where a is an integer ≥ 1, b is an integer ≥ 0, c is an integer ≥ 1, d is an integer ≥ 1, and e is an integer ≥ 0.

[0061] In different implementations, a can be 1, 2, 3, 4, etc., b can be 0, 1, 2, 3, etc., c can be 1, 2, 3, 4, etc., d can be 1, 2, 3, 4, etc., and e can be 0, 1, 2, 3, etc.

[0062] In some implementations, a is 1 or 2; b is 0, 1 or 2; c is 1 or 2; d is 1 or 2; and e is 0, 1 or 2.

[0063] In some implementations, the Linker is selected from at least one of the following structures:

[0064]

[0065] In this disclosure, "*" represents the site where the structure is connected to the structure of the prepolymer.

[0066] In some implementations, R1 is selected from at least one of the following structures:

[0067]

[0068] In some implementations, R2 is selected from at least one of the following structures:

[0069]

[0070] In some implementations, R2 is selected from at least one of the following structures:

[0071]

[0072] In some embodiments, the hydroxyl-containing acrylate includes at least one of hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate, and hydroxyethyl acrylate.

[0073] In some embodiments, the nanoparticles include at least one selected from ZrO2, TiO2, ZnO, and CeO2. Further, the average particle size of the nanoparticles is 10–40 nm, such as a range of 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, or any combination thereof. The titanium dioxide includes, but is not limited to, rutile titanium dioxide and anatase titanium dioxide.

[0074] In some embodiments, the mass percentage of nanoparticles in the capping agent is 20% to 50%, for example, it can be 20%, 25%, 30%, 35%, 40%, 45%, 50%, or any combination thereof. Having the mass of nanoparticles in the capping agent within this range helps to introduce nanoparticles into the polyurethane acrylic resin that improve refractive index while maintaining light transmittance. Furthermore, the content of nanoparticles in the capping agent helps to ensure dispersion stability. When the content of nanoparticles in the capping agent is too high, although the refractive index is improved, the light transmittance and uniformity deteriorate; when the content of nanoparticles in the capping agent is insufficient, the improvement in the refractive index of the polyurethane acrylic resin is not significant.

[0075] In some implementations, the capping agent can be purchased externally or made in-house.

[0076] In some embodiments, this disclosure provides an optional method for preparing a capping agent, comprising the following steps: stirring and dispersing surface-modified nanoparticles with hydroxyl-containing acrylate in a certain proportion to obtain a translucent milky white dispersion, which is the capping agent; wherein, the preparation of surface-modified nanoparticles includes: stirring and dispersing nanoparticles in an aqueous phase containing a surfactant for 2-4 hours; centrifuging to allow the particles to settle, discarding the supernatant, resuspending the particles in ultrapure water, repeating 2-3 times, centrifuging to collect the particles; and air-drying the particles naturally.

[0077] In some embodiments, the surfactant in the aqueous phase containing the surfactant is sodium dodecylbenzenesulfonate. Further, the dispersion concentration of the surfactant is 4 wt% to 6 wt%; the mass ratio of nanoparticles to the surfactant-containing aqueous phase is 1:(4-4.5). In some embodiments, the raw materials for preparing the polyurethane acrylic resin also include a polymerization inhibitor. Further, the polymerization inhibitor includes at least one selected from p-hydroxyanisole, methyl hydroquinone, and hydroquinone.

[0078] In some embodiments, the amount of polymerization inhibitor is 0.08% to 0.15% of the total mass of the prepolymer and the end-capping agent, for example, it can be 0.08%, 0.1%, 0.12%, 0.15%, or any combination thereof. The introduction of an appropriate amount of polymerization inhibitor effectively prevents the polymerization of double bonds in the end-capping agent during the reaction between the prepolymer and the end-capping agent in the polyurethane acrylic resin.

[0079] In some embodiments, the raw materials for preparing the prepolymer include isocyanates and trithiols in a molar ratio of (3 to 3.5):1;

[0080] Isocyanates contain the structure shown in Formula II:

[0081]

[0082] In different embodiments, the molar ratio of isocyanate and trithiol in the raw materials for preparing the prepolymer can be 3:1, 3.1:1, 3.2:1, 3.3:1, 3.4:1, 3.5:1, or any combination thereof.

[0083] It is understood that isocyanates can be one or more of the structures shown in Formula II with n≥1.

[0084] In some embodiments, the trithiol includes at least one selected from 1,3-propanedithiol-2-thioether ethylthiol, 2,3-dithio(2-mercapto)-1-propanethiol, 3,6,9-thioundecane-5-(2-thiomercaptobutyl)-1,11-dithiol, 3,6,9,12-thiotetradecane-7-(2-thiomercaptobutyl)-1,14-dithiol, and 3,6,9,12-thiotetradecane-7-(mercaptomethyl)-1,14-dithiol.

[0085] The structural formula of 1,3-propanedithiol-2-thioether ethylthiol is: The structural formula of 2,3-dithio(2-mercapto)-1-propanethiol is: The structural formula of 3,6,9-thioundecane-5-(2-thiomercaptobutyl)-1,11-dithiol is: The structural formula of 3,6,9,12-thiotetradecane-7(2-thiomercaptobutyl)-1,14-dithiol is: The structural formula of 3,6,9,12-thiotetradecane-7-(mercaptomethyl)-1,14-dithiol is:

[0086] In some embodiments, the raw materials for preparing the prepolymer also include a first catalyst, which includes at least one of dibutyltin dilaurate, dibutyltin dichloride, stannous octoate, dibutyltin diacetate, bismuth isooctanoate, zinc 2-ethylhexanoate, and zinc neodecanoate.

[0087] In practice, the amount of catalyst used is selected according to conventional catalytic dosage, including, but not limited to, the amount of the first catalyst being 0.05% to 1% of the mass of the reaction raw materials.

[0088] In some embodiments, the raw materials for preparing isocyanate substances as shown in Formula II include diisocyanate and dithiol in a molar ratio of (2 to 2.4):1.

[0089] In different embodiments, the molar ratio of diisocyanate to dithiol in the raw materials for preparing isocyanate substances as shown in Formula II can be 2:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1, or any combination thereof.

[0090] In some embodiments, the diisocyanate includes at least one of isophthalic dimethyl isocyanate, tetramethyl isophthalimide diisocyanate, toluene diisocyanate, and norbornene diisocyanate.

[0091] The diisocyanate used in this disclosure helps to introduce a suitable rigid structure into the resin, thereby improving the strength of the resin.

[0092] In some embodiments, the dithiol includes at least one of dithioethyl sulfide, 1,4-dithiam-2,5-di(methanethiol), 1,4-benzenedimethylthiol, 1,3-propanedithiol, 1,4-butanedithiol, and 2,2'-[1,4-butadiylbis(thio)]bisethylthiol.

[0093] The dithiols used in this disclosure help to increase the sulfur content in the resin backbone, thereby increasing the refractive index while ensuring that the resin does not easily turn yellow.

[0094] In some embodiments, the raw materials for preparing isocyanates as shown in Formula II further include a second catalyst, which includes at least one of dibutyltin dilaurate, dibutyltin dichloride, stannous octoate, dibutyltin diacetate, bismuth isooctanoate, zinc 2-ethylhexanoate, and zinc neodecanoate.

[0095] In practice, the amount of catalyst used is selected according to conventional catalytic dosage, including, but not limited to, the amount of the second catalyst being 0.05% to 1% of the mass of the reaction raw materials.

[0096] This disclosure also provides a method for preparing polyurethane acrylic resin, comprising the following steps: reacting the prepolymer with a capping agent at 85-95°C until the NCO value is 0.

[0097] In some embodiments, a polymerization inhibitor is added to the reaction system. Further, the amount of polymerization inhibitor used is 0.08% to 0.15% of the combined mass of the prepolymer and the capping agent.

[0098] In one specific embodiment, the preparation of polyurethane acrylic resin may include: adding a capping agent dropwise to the prepolymer under a protective atmosphere, controlling the system temperature below 70°C during the dropwise addition process, raising the temperature to 85–95°C after the dropwise addition is complete, adding a polymerization inhibitor, and maintaining the temperature for approximately 5–8 hours. The specific reaction time is controlled by detecting the NCO content in the reaction system using the di-n-butylamine method; the reaction is stopped when the NCO value in the reaction system reaches 0.

[0099] In some embodiments, the preparation of the prepolymer includes: reacting isocyanate and trithiol at 75–85°C under the action of a first catalyst until the NCO value is X1–2–X1%, where X1 = [126 / M1 + 3 × (M2 + M3 × 2)] × 100%, M1 is the relative molecular mass of the trithiol, M2 is the relative molecular mass of the dithiol, and M3 is the relative molecular mass of the diisocyanate. X1 represents the theoretical NCO value of the prepolymer; the actual measured NCO value is approximately 1%–2% lower than the theoretical NCO value.

[0100] In one specific embodiment, the preparation of the prepolymer may include: adding a trithiol dropwise to an isocyanate-based substance under a protective atmosphere, controlling the system temperature below 50°C during the dropwise addition process, raising the temperature to 75–85°C after the dropwise addition is complete, and maintaining the temperature for approximately 3–6 hours. The specific reaction time is controlled by detecting the NCO content in the reaction system using the di-n-butylamine method; the reaction is stopped when the NCO value in the reaction system reaches X1-2 to X1%.

[0101] In some embodiments, the preparation of isocyanates includes: reacting diisocyanate and dithiol at 65–75°C under the action of a second catalyst until the NCO value is X2-2 to X2%, where X2 = (84 / M2 + M3×2)×100%, M2 is the relative molecular mass of the dithiol, and M3 is the relative molecular mass of the diisocyanate. X2 is the theoretical NCO value of the isocyanate preparation; the actual tested NCO value is smaller than the theoretical NCO value, approximately 1%–2% lower.

[0102] In one specific embodiment, the preparation of isocyanates may include: adding a dithiol dropwise to a diisocyanate under a protective atmosphere, controlling the system temperature below 50°C during the dropwise addition, raising the temperature to 65–75°C after the dropwise addition is complete, and maintaining the temperature for approximately 3–6 hours. The specific reaction time is controlled by detecting the NCO content in the reaction system using the di-n-butylamine method; the reaction is stopped when the NCO value in the reaction system reaches X²⁻² to X²%.

[0103] In a second aspect, embodiments of this disclosure also provide a photocurable composition comprising, by weight, the following components: 70-80 parts of polyurethane acrylic resin, 20-30 parts of acrylate monomer, and 2-5 parts of photoinitiator; wherein the polyurethane acrylic resin is any one of the polyurethane acrylic resins provided in the first aspect of this disclosure.

[0104] The polyurethane acrylic resin disclosed herein is UV-curable. When formulated according to the above proportions, it yields a product possessing high refractive index, high light transmittance, and strength. In different embodiments, the amounts of each component, by weight, are as follows:

[0105] The amount of polyurethane acrylic resin can be 70 parts, 72 parts, 75 parts, 78 parts, 80 parts, or any combination thereof.

[0106] The amount of acrylate monomers can be 20 parts, 22 parts, 25 parts, 28 parts, 30 parts, or any combination thereof;

[0107] The amount of photoinitiator can be 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, 5 parts, or any combination thereof.

[0108] In some embodiments, the acrylate monomers include at least one of tricyclodecanediethanol diacrylate and tricyclodecanediethanol dimethyl diacrylate.

[0109] In some embodiments, the photoinitiator includes at least one of 1-hydroxycycloethylphenylacetone and (2,4,6-trimethylbenzoyl)diphenylphosphine oxide. The type of photoinitiator is not limited to this; any other initiator capable of initiating photocuring may be used.

[0110] Thirdly, embodiments of this disclosure also provide waveguide articles, which are mainly made of any one of the photocurable compositions in the second aspect.

[0111] In some embodiments, the density of the waveguide material is 1.25–1.35 g / cm³. 3 The transmittance of the waveguide product at 520nm is ≥82%, for example, it can be 82%~90% or 84%~90%; the refractive index of the waveguide product at 520nm is >1.64, for example, it can be 1.64~1.68.

[0112] In one specific embodiment, the preparation of the waveguide product includes: casting a photocurable composition into a light-transmitting mold, and then performing photocuring and thermocuring.

[0113] In some embodiments, photocuring includes: a light intensity of 5–15 mW / cm². 2 For example, it can be 5mW / cm 2 8mW / cm 2 10mW / cm 2 12mW / cm 2 15mW / cm 2 Or a range of any two of them; the light curing time is 1 to 5 minutes, for example, it can be 1 minute, 2 minutes, 3 minutes, 4 minutes, 5 minutes or a range of any two of them.

[0114] In some embodiments, thermosetting includes: a thermosetting temperature of 50–120°C, for example, a range of 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 90°C, 100°C, 110°C, 120°C, or any combination thereof; and a thermosetting time of 5–8 hours, for example, a range of 5 hours, 5.5 hours, 6 hours, 6.5 hours, 7 hours, 7.5 hours, 8 hours, or any combination thereof.

[0115] In practice, thermosetting treatment can be carried out according to a certain procedure, such as: raising the temperature from room temperature to 50±5℃ within 30 minutes, raising the temperature from 50±5℃ to 70±5℃ within 30 minutes, raising the temperature from 70±5℃ to 80±5℃ within 60 minutes, holding the temperature at 80±5℃ for 2.5 to 3.5 hours, raising the temperature from 80±5℃ to 120±5℃ within 180 minutes, lowering the temperature from 120±5℃ to 100±5℃ within 120 minutes, lowering the temperature from 100±5℃ to 50±5℃ within 60 minutes, and lowering the temperature from 50±5℃ to room temperature within 30 minutes to complete the thermosetting process.

[0116] Example 1

[0117] This embodiment provides a photocurable composition comprising the following components in parts by weight:

[0118] The mixture contains 75 parts polyurethane acrylic resin, 25 parts acrylate monomers, 3 parts photoinitiator, and 0.1 parts release agent (phosphate ester surfactant, such as lauryl phosphate).

[0119] Among them, the acrylate monomer is tricyclodecanediethanol dimethyl diacrylate, and the photoinitiator is photoinitiator 184.

[0120] The preparation of polyurethane acrylic resin includes:

[0121] (1) Preparation of isocyanates

[0122] Add 2 mol of m-phenylenedimethyl isocyanate (XDI) to a three-necked flask at room temperature. Then place the flask in dimethyl silicone oil, start stirring, add 0.3 g of dibutyltin dilaurate (DBTDL) and stir to dissolve. Heat the oil to 30°C. Add 1 mol of dimercaptoethyl sulfide to a constant pressure dropping funnel and slowly add it dropwise to the three-necked flask under nitrogen protection. The addition is completed in about 30 minutes, with the temperature controlled below 50°C during the addition. After the addition is complete, wait until the temperature of the reactants stops rising, then slowly increase the oil temperature to maintain the temperature of the reactants at 70±3°C and keep it at this temperature for 4 hours. Check the NCO content of the reactants using the di-n-butylamine method. If NCO ≤ 31.65%, the reaction is complete, and isocyanate compounds are obtained. The reaction route is as follows (n can be an integer ≥ 1):

[0123]

[0124] (2) Preparation of prepolymer

[0125] The material obtained from step (1) was directly heated and stirred at 50°C. 0.5 g of dibutyltin dichloride was added and stirred until dissolved. Then, under nitrogen protection, 0.33 mol of 2,3-dithio(2-mercapto)-1-propanethiol was added dropwise using a constant-pressure dropping funnel over 30 minutes. The temperature was controlled below 50°C during the addition. After the addition was complete and the temperature of the reactants stopped rising, the oil temperature was slowly increased to maintain the temperature at 80±3°C for 4 hours. The NCO content of the reactants was checked using the di-n-butylamine method. If NCO ≤ 15.92%, the reaction was considered complete, and the prepolymer was obtained. The reaction route is as follows:

[0126]

[0127] (3) Preparation of polyurethane acrylic resin

[0128] The material obtained from step (2) was directly heated and stirred at 60°C. Under nitrogen protection, a capping agent containing 1.01 mol of hydroxyethyl methacrylate (containing approximately 34 wt% ZrO2 nanoparticles with a particle size of 10–40 nm) was added dropwise using a constant-pressure dropping funnel. The addition was completed in 60 minutes, with the temperature controlled below 70°C during the addition. After the addition was completed, once the temperature of the reactants stopped rising, the oil temperature was slowly increased to maintain the temperature of the reactants at 90 ± 3°C. Then, 0.1% of the total reactant volume of p-hydroxyanisole was added and kept at this temperature for 6 hours. The NCO content of the reactants was checked using the di-n-butylamine method. If NCO ≤ 0, the reaction was considered complete, and polyurethane acrylic resin was obtained. The reaction route is as follows:

[0129]

[0130] The preparation method of the end-capping agent includes: adding 10g of sodium dodecylbenzenesulfonate to 200g of deionized water and stirring to disperse evenly; then adding 50g of nano-ZrO2 particles with a particle size of 10-40nm and stirring thoroughly for 3h; centrifuging at high speed (e.g., 10000rpm) to allow the particles to settle, and discarding the supernatant; resuspending the particles in ultrapure water, repeating 3 times, and then naturally drying the collected particles to obtain modified nanoparticles. Take 68g of modified nanoparticles and 132g of hydroxyethyl methacrylate, stir and disperse until a semi-transparent milky white dispersion is obtained, which is the end-capping agent.

[0131] The method for preparing the photocurable composition includes the following steps:

[0132] The photoinitiator was dissolved in an acrylate monomer. After complete dissolution, a release agent and polyurethane acrylic resin were added and stirred until homogeneous to obtain a photocurable composition.

[0133] Example 2

[0134] This embodiment refers to the photocurable composition and its preparation method of Example 1, the only difference being that the polyurethane acrylic resin is different.

[0135] The preparation of the polyurethane acrylic resin in this embodiment is the same as in Example 1, except that:

[0136] Replace the dithioethyl sulfide in step (1) with an equimolar amount of 1,4-dithiane-2,5-di(methanethiol), and replace the isophenyl dimethyl isocyanate with an equimolar amount of norbornane diisocyanate (NBDI).

[0137] Replace 2,3-dithio(2-mercapto)-1-propanethiol in step (2) with an equimolar amount of 1,3-propanedithiol-2-thioether ethylthiol.

[0138] Example 3

[0139] This embodiment refers to the photocurable composition and its preparation method of Example 1, the only difference being that the polyurethane acrylic resin is different.

[0140] The preparation of the polyurethane acrylic resin in this embodiment is the same as in Example 1, except that:

[0141] Replace the dimercaptoethyl sulfide in step (1) with an equimolar amount of 2,2'-[1,4-butadienebis(thio)]diethyl mercaptan, and replace the isophthalic dimethyl isocyanate with an equimolar amount of tetramethyl isophthalimide diisocyanate (TMXDI).

[0142] Example 4

[0143] This embodiment refers to the photocurable composition and its preparation method of Example 1, the only difference being that the polyurethane acrylic resin is different.

[0144] The preparation of the polyurethane acrylic resin in this embodiment is the same as in Example 1, except that:

[0145] Replace the dimercaptoethyl sulfide in step (1) with an equimolar amount of 1,4-benzenedimethyl mercaptan;

[0146] Replace 2,3-dithio(2-mercapto)-1-propanethiol in step (2) with an equimolar amount of 1,3-propanedithiol-2-thioether ethylthiol.

[0147] Example 5

[0148] This embodiment refers to the photocurable composition and its preparation method of Example 1, the only difference being that the polyurethane acrylic resin is different.

[0149] The preparation of the polyurethane acrylic resin in this embodiment is the same as in Example 1, except that:

[0150] Replace the dimercaptoethyl sulfide in step (1) with an equimolar amount of 1,4-butanedithiol.

[0151] Example 6

[0152] This embodiment refers to the photocurable composition and its preparation method in Example 1, the only difference being the amount of each component in the photocurable composition.

[0153] The photocurable composition of this embodiment includes the following components by weight: 85 parts polyurethane acrylic resin, 15 parts acrylate monomer, 3 parts photoinitiator, and 0.1 parts release agent.

[0154] Example 7

[0155] This embodiment refers to the photocurable composition and its preparation method in Example 1, the only difference being the amount of each component in the photocurable composition.

[0156] The photocurable composition of this embodiment includes the following components by weight: 65 parts polyurethane acrylic resin, 35 parts acrylate monomer, 3 parts photoinitiator, and 0.1 parts release agent.

[0157] Examples 8-14

[0158] This embodiment provides a method for preparing a waveguide product, including the following steps:

[0159] The photocurable composition is poured into a high-precision glass mold (mold transmittance > 90%), and then the mold is placed in a photocuring chamber for photocuring; then the mold is transferred to an oven for heat curing.

[0160] In the preparation methods of waveguide products in Examples 8 to 14, the photocurable compositions of Examples 1 to 7 are used respectively.

[0161] In the UV curing process, the UV irradiation intensity was set to 10 mW / cm². 2 The UV curing time is 3 minutes;

[0162] During thermosetting, the temperature is increased uniformly from room temperature to 50℃ in 30 minutes; from 50℃ to 70℃ in 30 minutes; from 70℃ to 80℃ in 1 hour; then held at 80℃ for 3 hours; from 80℃ to 120℃ in 3 hours; from 120℃ to 100℃ in 2 hours; from 100℃ to 50℃ in 1 hour; and from 50℃ to room temperature in 30 minutes, completing the thermosetting process.

[0163] Comparative Example 1

[0164] Comparative Example 1 refers to the photocurable composition and preparation method of Example 1, except that the polyurethane acrylic resin is different.

[0165] The preparation of the polyurethane acrylic resin in Comparative Example 1 is the same as in Example 1, except that:

[0166] In step (3), the capping agent does not contain ZrO2 nanoparticles.

[0167] Comparative Example 2

[0168] Comparative Example 2 refers to the photocurable composition and preparation method of Example 1, except that the polyurethane acrylic resin is different.

[0169] The preparation of the polyurethane acrylic resin in Comparative Example 2 is the same as in Example 1, except that:

[0170] Replace the dimercaptoethyl sulfide in step (1) with an equimolar amount of diethylene glycol.

[0171] Comparative Examples 3-4

[0172] The preparation methods of waveguide products of Comparative Examples 3 and 4 refer to Example 8, except that the waveguide products of Comparative Examples 3 and 4 are prepared by replacing the photocurable composition used in Example 8 with the photocurable composition of Comparative Examples 1 and 2.

[0173] Experimental Example

[0174] The transmittance, refractive index, impact resistance, and density of the waveguide products prepared in Examples 8-14 and Comparative Examples 3-4 were tested, and the test results are shown in Table 1. The transmittance test was conducted according to GB / T2410-2008 "Determination of transmittance and haze of transparent plastics", the refractive index test was conducted according to GJB 8687-2015 "Verification Procedure for Refractive Index and Thickness Testers of Optical Thin Films", and the impact resistance test was conducted according to GB 39552.1-2020 "Sunglasses and Sunglass Lenses Part 1: General Requirements".

[0175] Table 1. Test results of waveguide products from different embodiments and comparative examples.

[0176]

[0177]

[0178] Based on the above test results, the polyurethane acrylic resin disclosed herein has thiocarbamate blocks with high sulfur content in its main chain, and the end-capping groups contain high-refractive-index nanoparticles and photocurable acrylate groups. Through structural and elemental control of the polyurethane acrylic resin, it achieves a high refractive index of over 1.64, approximately 1.25–1.35 g / cm³.3 It has a low density after curing and high transmittance after light curing, while also exhibiting excellent impact resistance.

[0179] Finally, it should be noted that the above-described embodiments are merely specific implementations of this disclosure, used to illustrate the technical solutions of this disclosure, and not to limit it. The protection scope of this disclosure is not limited thereto. Although this disclosure has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features, within the scope of the technology disclosed in this disclosure. Such modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this disclosure, and should all be covered within the protection scope of this disclosure. Therefore, the protection scope of this disclosure should be determined by the protection scope of the claims.

Claims

1. A polyurethane acrylic resin, characterized in that, The raw materials for preparing the polyurethane acrylic resin include prepolymer and end-capping agent; The prepolymer contains the structure shown in Formula I: Wherein, Linker is the residue after the reaction of trithiol with NCO, R1 is the residue after the reaction of diisocyanate with SH, R2 is the residue after the reaction of dithiol with NCO, and n is an integer ≥1; The capping agent comprises a hydroxyl-containing acrylate and nanoparticles dispersed in the hydroxyl-containing acrylate; the refractive index of the nanoparticles is ≥2.0; The molar ratio of reactive NCO in the prepolymer to hydroxyl-containing acrylate in the capping agent is 1:(1-1.2).

2. The polyurethane acrylic resin according to claim 1, characterized in that, Linker has the following structure: Where a is an integer ≥ 1, b is an integer ≥ 0, c is an integer ≥ 1, d is an integer ≥ 1, and e is an integer ≥ 0.

3. The polyurethane acrylic resin according to claim 1, characterized in that, Linker is selected from at least one of the following structures:

4. The polyurethane acrylic resin according to claim 1, characterized in that, It has at least one of the following characteristics: (1) R1 is selected from at least one of the following structures: (2) R2 is selected from at least one of the following structures: (3) The hydroxyl-containing acrylate includes at least one of hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate and hydroxyethyl acrylate; (4) The nanoparticles include at least one of ZrO2, TiO2, ZnO and CeO2; (5) The average particle size of the nanoparticles is 10-40 nm; (6) In the capping agent, the mass percentage of the nanoparticles is 20% to 50%.

5. The polyurethane acrylic resin according to claim 1, characterized in that, The raw materials for preparing the polyurethane acrylic resin also include polymerization inhibitors; The polymerization inhibitor includes at least one of p-hydroxyanisole, methyl hydroquinone, and hydroquinone.

6. The polyurethane acrylic resin according to claim 1, characterized in that, The raw materials for preparing the prepolymer include isocyanate substances in a molar ratio of (3-3.5):1 and the trithiol; The isocyanate contains the structure shown in Formula II:

7. The polyurethane acrylic resin according to claim 1 or 6, characterized in that, The ternary thiols include at least one selected from 1,3-propanedithiol-2-thioether ethyl thiol, 2,3-dithio(2-mercapto)-1-propanethiol, 3,6,9-thioundecane-5-(2-thiomercaptobutyl)-1,11-dithiol, 3,6,9,12-thiotetradecane-7-(2-thiomercaptobutyl)-1,14-dithiol, and 3,6,9,12-thiotetradecane-7-(mercaptomethyl)-1,14-dithiol.

8. The polyurethane acrylic resin according to claim 6, characterized in that, The raw materials for preparing the isocyanate include the diisocyanate and the dithiol in a molar ratio of (2-2.4):

1.

9. The polyurethane acrylic resin according to claim 1 or 8, characterized in that, The diisocyanate includes at least one of isophthalic dimethyl isocyanate, tetramethyl isophthalimide diisocyanate, toluene diisocyanate, and norbornane diisocyanate; The dithiols include at least one of dithioethyl sulfide, 1,4-dithiam-2,5-di(methanethiol), 1,4-benzenedimethylthiol, 1,3-propanedithiol, 1,4-butanedithiol, and 2,2'-[1,4-butadiylbis(thio)]bisethylthiol.

10. The polyurethane acrylic resin according to claim 6, characterized in that, The raw materials for preparing the prepolymer and the raw materials for preparing the isocyanate each independently include a catalyst; The catalyst includes at least one of dibutyltin dilaurate, dibutyltin dichloride, stannous octoate, dibutyltin diacetate, bismuth isooctanoate, zinc 2-ethylhexanoate, and zinc neodecanoate.

11. A photocurable composition, characterized in that, Includes the following components by weight: The mixture comprises 70-80 parts of polyurethane acrylic resin, 20-30 parts of acrylate monomers, and 2-5 parts of photoinitiator; wherein the polyurethane acrylic resin is the polyurethane acrylic resin according to any one of claims 1-10.

12. The photocurable composition according to claim 11, characterized in that, The acrylate monomers include at least one of tricyclodecanediethanol diacrylate and tricyclodecanediethanol dimethyl diacrylate.

13. A waveguide product, characterized in that, It is mainly prepared from the photocurable composition described in claim 11 or 12.

14. The waveguide article according to claim 13, characterized in that, It has at least one of the following characteristics: (1) The density of the waveguide product is 1.25–1.35 g / cm³. 3 ; (2) The transmittance of the waveguide product at 520nm is ≥82%; (3) The refractive index of the waveguide product at 520nm is >1.64.

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