High-refractive-index resin materials within the specialized segment of UV-curable materials—characterized by a refractive index range of 1.53–1.7—have emerged as core raw materials for high-end applications such as optical coatings, high-gloss wood finishes, 3C optical components, and LED packaging. Unlike conventional UV materials, which merely fulfill basic curing requirements, the key advantages of high-refractive-index UV resins and their monomers stem from precise molecular structure design and rigorous synthesis process control. Their high refractive index is not an accidental feature; rather, it exemplifies the principle that “structure determines performance.”
I. First, establish the core concept: the fundamental principle of refraction for UV high-refractive-index materials
The essence of the refractive index is a material’s ability to impede the propagation speed of light, and its magnitude is closely related to the polarizability of the material’s molecules and their packing density. To achieve a refractive index exceeding 1.53—or even as high as 1.7—the key lies in introducing high-polarizability functional groups into the molecular structures of both the resin and the monomer; this constitutes the fundamental principle for synthesizing all high-refractive-index UV materials.
Common functional groups with high polarizability, ranked by their contribution to refractive index, are as follows: aromatic rings (benzene ring, naphthalene ring) <heterocyclic rings (thiophene ring, furan ring) <halogen atoms (Br, I) <thioether bonds (-S-). These functional groups can significantly enhance molecular polarizability while ensuring tight intermolecular packing, thereby achieving high refractive indices. The core requirement for UV-curable resins is to introduce polymerizable acrylate double bonds (-OCOCH=CH₂) into the molecule, enabling rapid crosslinking and curing of the material under UV irradiation. Consequently, the synthesis of high-refractive-index UV-resins and their monomers fundamentally relies on the precise integration of high-refractive-index functional groups with curable reactive groups.
II. UV High-Refractive-Index Monomer: A fundamental core material characterized by low molecular weight, high reactivity, and high refractive index.
UV-grade high-refractive-index monomers serve as both the diluent and the crosslinked backbone in high-refractive-index systems, and must simultaneously satisfy three key requirements: a refractive index ranging from 1.53 to 1.7, low viscosity for easy formulation, and high reactivity of the acrylate double bonds. Their synthesis is centered on the core strategy of “high-refractive-index monomer precursor + reactive end-capping,” with three mainstream synthetic routes available to meet diverse refractive index requirements across different ranges.
1. Aromatic high-refractive-index monomers (refractive index: 1.53–1.62; mainstream standard variant)
This is currently the most widely used category of high-refractive-index monomers; its core mechanism relies on the high polarizability of the aromatic ring to achieve high refractive index, featuring a simple synthesis pathway and excellent cost-performance ratio, making it suitable for a wide range of mid-to-high-end applications.
• Synthetic core matrix: polyhydroxylated aromatic compounds such as bisphenol A, resorcinol, and naphthalenediol; benzene or naphthalene rings serve as the high-refractive-index core carrier.
• Synthesis mechanism: Esterification/ester exchange reaction, in which the hydroxyl group (-OH) of the aromatic precursor undergoes condensation with acrylic acid (or methyl acrylate) to introduce an acrylate double bond at the molecular terminus, thereby retaining the high refractive index characteristics of the aromatic ring while imparting UV-curable functionality;
• Typical products and specifications: bisphenol A epoxy acrylate monomer and naphthalenediol diacrylate; refractive index ranges from 1.55 to 1.62, moderate viscosity, and excellent compatibility with various UV resins.
2. Sulfide-based high-refractive-index monomers (refractive index: 1.60–1.68; primary product line: medium-to-high refractive index)
When the refractive index requirement exceeds the 1.60 threshold, a simple aromatic ring no longer suffices; the introduction of a thioether bond can further increase the refractive index without compromising curing activity, making it the core choice for the medium-to-high refractive index range.
• Synthetic core matrix: sulfur-containing hydroxyl compounds (e.g., thiobisphenols, thiol alcohols), wherein the polarizability of the thioether bond is significantly higher than that of conventional ether bonds (-O-), resulting in a more pronounced contribution to refractive index;
• Synthetic reaction mechanism: The process consists of two steps—first, a nucleophilic substitution reaction is employed to construct a polyol precursor bearing a thioether bond; second, an esterification reaction is used to introduce an acrylate double bond. The key objectives are to ensure the stability of the thioether bond against decomposition while simultaneously enhancing the grafting efficiency of the double bonds.
• Key Advantages: Compared to aromatic monomers, thioether monomers exhibit superior flexibility of the cured paint film and enhanced resistance to yellowing, making them suitable for applications with stringent performance requirements, such as 3C optical components and LED packaging.
3. Halogen-substituted high-refractive-index monomers (refractive index: 1.65–1.70; high-refractive-index variant)
To meet the demand for high refractive indices of 1.65 or even 1.7, it is necessary to introduce halogen atoms (bromine or iodine) for molecular modification. The high atomic mass and high polarizability of these halogen atoms enable breakthroughs in refractive performance, making this class of UV monomers a high-end category characterized by superior refractive properties.
• Synthetic core scaffold: brominated bisphenol A and iodinated aromatic diols, in which bromine/iodine atoms replace hydrogen atoms on the aromatic ring, thereby maximizing molecular polarizability;
• Synthetic reaction mechanism: Taking brominated bisphenol A as an example, the compound first reacts with epichlorohydrin to form a brominated epoxy resin precursor, which then undergoes ring-opening esterification with acrylic acid to introduce a curable double bond. Throughout this process, the reaction temperature must be carefully controlled to prevent the loss of halogen atoms, which could adversely affect material properties.
• Key considerations: Although halogen substitution can significantly increase the refractive index, it is essential to balance the material’s viscosity with its environmental friendliness; consequently, low-halogen, environmentally friendly high-refractive-index monomers have become a primary focus in synthetic research and development.
III. UV-High-Refractive-Index Resin: Macromolecular backbone provides structural support, serving as the core guarantee for performance and compatibility.
UV high-refractive resin serves as the primary film-forming component in high-refractive systems. Its refractive index must be compatible with that of the monomer (1.53–1.7), and it also plays a pivotal role in enhancing the paint film’s adhesion, scratch resistance, and weather resistance. The fundamental principle of its synthesis lies in the construction of a “high-refractive prepolymer,” which involves densely incorporating high-refractive functional groups into the macromolecular chain while ensuring both photopolymerization activity and the overall performance of the paint film. The mainstream synthesis systems are categorized into two types, each tailored to different application scenarios.
1. Epoxy acrylate high-refractive-index resins (most widely used; refractive index: 1.53–1.63)
Based on high-refractive-index epoxy monomer, this material is currently the most technologically mature and cost-effective UV high-refractive resin, widely used in high-gloss wood coatings and conventional optical coatings.
• Synthesis Principle: An open-ring esterification reaction is employed, utilizing high-refractive-index epoxy monomers (e.g., bisphenol A epoxy, naphthalene-based epoxy, brominated epoxy, etc.) which undergo an open-ring reaction with acrylic acid under the influence of a catalyst (such as triethylamine). Upon ring opening, the epoxy groups react with the carboxyl groups of acrylic acid, thereby introducing a large number of acrylate double bonds into the resin molecular chains while retaining the high-refractive-index functional groups—such as aromatic rings or halogens—present in the monomer.
• Performance Tuning: The refractive index is adjusted by selecting different epoxy monomers—bisphenol A-based types (1.53–1.58), naphthalene-ring-based types (1.58–1.61), and brominated types (1.61–1.63); the molecular weight and viscosity are further regulated by controlling the degree of reaction, enabling compatibility with diverse application techniques such as spray coating, roller coating, and dip coating.
2. Polyurethane acrylate high-refractive-index resins (high-performance grade, refractive index 1.55–1.68)
Combining high refractive index, high flexibility, and superior weather resistance, this resin belongs to the mid-to-high-end high-refractive resin category and is suitable for applications such as 3C optical components and high-end wood finishing.
• Synthesis principle: stepwise addition polymerization followed by esterification end-capping, carried out in three stages. In the first stage, a high-refractive-index polyol (thiol polyol or brominated polyol) reacts with a diisocyanate via addition to yield a polyurethane prepolymer containing-NCO groups; in the second stage, a hydroxyl-containing acrylate (e.g., hydroxyethyl acrylate) reacts with the-NCO groups of the prepolymer to introduce acrylate double bonds via end-capping; in the third stage, the refractive index and flexibility of the resin are controlled by adjusting the feed ratios of the raw materials.
• Core Advantages: The urethane bonds (-NHCOO-) within the molecular chain enhance the adhesion and toughness of the paint film; when combined with thioether bonds and bromine-containing groups, the formulation achieves a balance between refractive properties and overall performance. After curing, the resulting paint film exhibits significantly superior scratch resistance, yellowing resistance, and chemical resistance compared to conventional epoxy acrylate resins.
Supplement: Key Control Considerations for the Synthesis of High-Refractive-Index Resin
1. High density of refractive index-functional groups: The higher the proportion of aromatic rings, thioether bonds, and halogen atoms within the molecular chain, the higher the refractive index; it is therefore necessary to balance density and resin viscosity to avoid adversely affecting application performance.
2. Active double-bond grafting efficiency: The double-bond grafting efficiency directly determines the UV curing rate; it is essential to ensure that the grafting efficiency is ≥90% to guarantee rapid and complete curing.
3. Molecular Stability: During the synthesis process, strict control of temperature and catalyst dosage is required to prevent decomposition of high-refractive-index functional groups, thereby ensuring long-term stability of the resin’s refractive index.
IV. Bidirectional Empowerment in Synthetic Applications: Technical Trends in High-Refractive-Index UV Materials
The synthesis of UV high-refractive-index resins with monomers has consistently evolved along three key axes— “higher refractive index, superior performance, and enhanced scenario compatibility” —with technological advancements and application requirements being deeply intertwined:
1. Green synthesis: Reduce halogen usage by developing halogen-free high-refractive-index monomers/resins, replacing brominated modifications with a combination of thioether bonds and multiple aromatic rings, thereby meeting the demands of industries under increasingly stringent environmental regulations;
2. Low-viscosity enhancement: By optimizing the molecular structure, the viscosity of the high-refractive-index monomer/resin system is reduced, thereby decreasing the amount of diluent required, while enhancing the solid content and curing efficiency of the formulation;
3. Customized Synthesis: Tailored solutions for diverse application scenarios—high-gloss wood finishes prioritize a refractive index of 1.55–1.60 combined with high resistance to yellowing, while optical components prioritize a refractive index of 1.65–1.70 combined with high transparency, enabling a “one material, one solution” approach.
V. UV High-Refraction Monomer Synthesis Scheme (3 mainstream variants, covering the full refractive range)
Option 1: Aromatic high-refractive-index monomer (refractive index: 1.53–1.62; preferred for general-purpose and mass-production applications)
Ideal applications: high-gloss wood finishes and conventional optical coatings—offering the best cost-performance ratio.
1. Core raw materials (molar ratio 1:2.1–2.2): bisphenol A (high-refractive-index monomer), acrylic acid (source of active double bonds), triethylamine (catalyst), and hydroquinone (polymerization inhibitor) = 1:2.15:0.03:0.005
2. Synthesis Route
1. Add bisphenol A to the reaction vessel, heat to 60 °C, purge with nitrogen three times, and maintain the temperature while stirring until complete melting is achieved;
2. Add acrylic acid and the catalyst triethylamine sequentially; after stirring uniformly, heat the mixture to 90–95 °C, maintain the temperature constant for 4–5 h, and monitor the acid value in real time (final acid value < 5 mg KOH/g);
3. Add the polymerization inhibitor hydroquinone, cool the mixture to 50 °C, and perform vacuum distillation (vacuum pressure: –0.095 MPa; temperature: 60 °C) to remove unreacted monomers;
4. Filter the mixture and discharge the product to obtain bisphenol A epoxy acrylate monomer (refractive index adjustable from 1.55 to 1.62).
3. Key parameters: reaction temperature fluctuation ≤ ±2 °C, vacuum distillation time 1–1.5 h, to prevent double bond self-polymerization.
Option 2: Thioether-based high-refractive-index monomers (refractive index: 1.60–1.68; medium-to-high refractive index / yellowing-resistant variant)
Suitable applications: 3C optical components, LED packaging; features excellent flexibility and weather resistance.
1. Core raw materials: Thiobisphenol (high-refractive-index monomer), hydroxyethyl acrylate, toluene diisocyanate, and dibutyltin(II) laurate (catalyst), in a molar ratio of 1:2.05:2.05:0.02; and a polymerization inhibitor, p-hydroxyanisole, at 0.005% (based on the total mass of raw materials).
2. Synthesis Route
1. Add thiodibenzyl ether and toluene diisocyanate to the reaction vessel; under a nitrogen atmosphere, heat the mixture to 70 °C, stir the reaction mixture for 2 h, and prepare a thioether prepolymer containing-NCO groups;
2. Add the mixture of hydroxyethyl acrylate and the catalyst dropwise over 1 h; after completion of the addition, heat the mixture to 80 °C and maintain this temperature for 3 h, monitoring the-NCO group content (end-point content <0.1%).
3. Add a polymerization inhibitor, cool the mixture to 45 °C, remove low-molecular-weight impurities under reduced pressure, filter off the filtrate, and obtain a thioether-type high-refractive-index monomer.
3. Key parameters: The temperature during the dropwise addition process must be strictly controlled between 70–75 °C to prevent runaway polymerization; the retention rate of sulfide bonds in the final product shall be ≥98% to ensure that the refractive properties meet the required standards.
Option 3: Brominated halogen-based high-refractive-index monomers (refractive index: 1.65–1.70; high-refractive-index variant)
Application scenarios: high-end optical components and high-refractive-index coatings—setting the benchmark for refractive performance.
1. Core raw materials: brominated bisphenol A: epichlorohydrin: acrylic acid: dibutyl ether of boron trifluoride (catalyst) = 1:2.2:2.1:0.025 (molar ratio); polymerization inhibitor phenothiazine: 0.006%
2. Synthesis Route
1. Add brominated bisphenol A and epichlorohydrin to the reaction vessel, add the catalyst, and heat the mixture to 85 °C; after reacting for 3 h, the brominated epoxy resin precursor was obtained;
2. Add acrylic acid, heat to 95–100 °C, and carry out the ring-opening esterification reaction for 5–6 h until the endpoint acid value reaches <4 mg KOH/g;
3. Perform cooling and pressure reduction distillation, filter the mixture, and discharge the product to obtain brominated epoxy acrylate monomer (with a maximum refractive index of up to 1.7).
3. Key parameters: Strict control of halogen residues, with a bromine atom release rate <0.5%; finished products must undergo environmental compliance testing to meet low-halogen regulatory requirements.
VI. UV High-Refractive-Index Resin Synthesis Scheme (Category 2 Core Product: Film-Forming Core)
Option 1: Epoxy acrylate high-refractive-index resin (refractive index: 1.53–1.63; mainstream variant / cost-controlled)
Applicable scenarios: high-gloss wood finishes and general-purpose optical coatings; mature technology with easy mass production.
1. Core raw materials: high-refractive-index epoxy monomer (bisphenol A / naphthalene ring / brominated epoxy, optional); acrylic acid; triethylamine (catalyst); hydroquinone (polymerization inhibitor) = 1:1.8–2.0:0.025:0.004 (molar ratio)
2. Synthesis Route
1. Purge the reaction vessel with nitrogen; add the high-refractive-index epoxy monomer; heat to 55 °C and stir until fully dissolved; then add the catalyst triethylamine.
2. Slowly add acrylic acid dropwise over 1.5–2 h, maintaining the temperature between 60–65 °C during the addition process to prevent localized overheating;
3. After addition, heat the mixture to 85–90 °C, maintain a constant temperature for 6–7 h, and then determine the epoxy value (end-point epoxy value <0.02 eq/100 g);
4. Add a polymerization inhibitor, cool the mixture to 50 °C, perform vacuum distillation for 2 h, and filter off the filtrate.
3. Performance Tuning: Select bisphenol A epoxy monomer → refractive index 1.53–1.58; naphthalene-based epoxy → 1.58–1.61; brominated epoxy → 1.61–1.63.
Option 2: Polyurethane acrylate high-refractive-index resin (refractive index: 1.55–1.68; high-performance variant)
Application scenarios: high-end wooden products and 3C optical components; features three key advantages: scratch resistance, resistance to yellowing, and flexibility.
1. Core raw materials: thiol polyol (high-refractive-index polyol); hexamethylenediisocyanate (HDI); hydroxyethyl acrylate (HEA); dibutyltin(II) tetracosanoate (catalyst); ratio = 1:2.0:2.0:0.02 (molar ratio); and 0.005% hydroxybenzyl ether as a polymerization inhibitor.
2. Synthesis Route
1. Under nitrogen protection, the thiol polyol and HDI were charged into the reaction kettle, the temperature was raised to 75 °C, and the catalyst was added; the reaction was then proceeded for 2.5 h to prepare a polyurethane prepolymer (with monitored NCO content meeting the specified requirements);
2. Cool to 65 °C, then slowly add HEA dropwise; after 1 h of addition, raise the temperature to 75 °C and maintain this temperature for 4 h until the –NCO content falls below 0.1 %;
3. Add a polymerization inhibitor, cool the mixture to 40 °C, remove low molecular weight components under reduced pressure, and filter to obtain the final resin product.
3. Key parameters: The prepolymerization reaction requires strict control of the NCO content, with a deviation of ≤ ±0.2%, to ensure that the subsequent double-bond grafting yield meets the required specifications.
VII. Post-synthesis Testing and Performance Control (Mandatory Item)
1. Basic Testing: Refractive index (Abbe refractometer, 25 °C), viscosity (rotational viscometer, 25 °C), and acid value/epoxy value/—NCO content (titration method); products may be stored in the warehouse only if all three parameters meet the specified requirements;
2. Performance Testing: Prepare a mixture of resin and the corresponding monomer in a 1:1 ratio, add 3% photoinitiator TPO, and perform UV curing (energy: 1200 mJ/cm²); then test the paint film adhesion (100-point scratch test), yellowing resistance (UV aging for 200 h), and hardness (pencil hardness).
3. Stability Test: The finished product shall be sealed and stored in a cool place at 25 °C for 3 months; it shall be considered qualified if the refractive index fluctuation is ≤ ±0.002.
VIII. Key Considerations for Mass Production
1. Equipment: A stainless steel reaction kettle shall be selected, equipped with a precision temperature control system and a nitrogen protection system; the vacuum level of the vacuum distillation system shall be stably maintained between-0.095 and-0.1 MPa.
2. Environmental Protection: Halogen-containing products shall be equipped with exhaust gas treatment and solid waste recovery systems; for thioether-containing products, strict control must be exercised to prevent odor leakage during reactions.
3. Batch Control: Retain samples for each batch, document the raw material batch number, process parameters, and test results, to ensure traceability.
Breaking the 1.4 Limit: Ultra-Low Refractive-Index Resin with UV Curing for Optical Anti-Reflective Applications
In optical design, high-refractive-index resin is used to concentrate and enhance light intensity, while low-refractive-index resin is used to reduce reflection and improve transmittance.
If nano-titanium dioxide serves as the “optical gain engine” for elevating the refractive index, then fluorine modification, a porous structure, and specialized monomer systems constitute the core technologies for reducing the refractive index of UV resin to below 1.40.
Today, we utilize real-world industry data to conduct an in-depth analysis of the principles, formulations, selection criteria, and applications of UV-curable resins with an ultra-low refractive index of n<1.4.
I. Industry Pain Points: Why ultra-lowrefractive index resins with a ratio below 1.4 are needed.
The refractive indices of conventional acrylate UV resins typically range from 1.50 to 1.58.
Conventional modified low-refractive-index resins typically achieve a refractive index range of 1.42–1.48.
However, high-end optical coating technology must overcome the 1.4 bottleneck:
1. Essential requirement for the base layer of anti-reflective coatings
Principle of optical interference: The lower the refractive index of the film layer compared to that of air (n=1.00), the lower its reflectivity.
n=1.35–1.40 represents the optimal low-refraction range for mass production using current wet UV processing technology.
2. Increase screen transmittance
For the matching of mobile phones, AR lenses, and optical thin-film multilayer coatings, the layers must be stacked alternately in high and low refractive indices.
In the absence of low-reflection layers with a thickness of up to 1.4 mm, the overall light transmittance will decrease by 2%–5%.
3. Eliminate rainbow patterns and glare
Imbalanced refractive index matching is the primary cause of rainbow patterns, ghosting, and other optical issues in lenses, cover plates, and optical coatings.
II. Core Principle: How to compress the UV resin to below 1.40.
Fundamental formula for refractive index: molar refractive index of the molecule / molecular volume
There are only two ways to reduce the refractive index:
Reduce molecular polarizability and increase free-volume pores.
Two reference technical pathways for industry maturity:
① Fluorine modification (a commonly used approach).
The C–F bond exhibits extremely low polarizability and a highly concentrated electron cloud, making it the most effective functional group for reducing the refractive index of organic materials.
Ordinary acrylate: n ≈ 1.52
Fluorinated acrylates: n ≈ 1.38–1.40
Perfluorinated modification can consistently achieve n = 1.35–1.38.
② Nanoporous hole structure (high-end solution).
Introduction of hollow silica nanofillers (Hollow SiO₂)
Do internal air pores (n=1.0) reduce the overall refractive index of the system?
The higher the doping concentration, the lower the refractive index:
30% hollow silicon: n≈1.40.
50% hollow silicon: n ≈ 1.35–1.37.
III. Selection of Key Raw Materials (Benchmarking against commonly used monomer systems).
High refractive index achieved via TiO₂; low refractive index achieved via fluorine monomer + hollow silica + low-polarity dilution monomer.
Fully compatible with UV-curable systems; can be blended with NVP, HDDA, and DEGDMA for formulation adjustment.
① Ultra-low folding core monomer (essential)
1. Fluorinated acrylate monomer
The system features directly tunable refractive index, exceptional weather resistance, low surface energy, and stain resistance.
2. Isobornyl esters: IBOA/THFA
Characterized by low polarization and a large molecular volume, with a baseline refractive index of approximately 1.43, this compound serves as the core monomer for transition regulation.
② Functional diluent monomer (viscosity reduction + fold stability enhancement)
DEGDMA、EO2HDDA。
It exhibits low polarity, low shrinkage, and excellent compatibility; it is used to adjust the viscosity of fluorine-based systems without increasing the refractive index.
③ Core reduction-filling material (hollow silica)
Particle size: 50–100 nm; dense shell; porosity: 30%–50%.
It does not compromise transparency, exhibits low opaquity, and is the only inorganic low-refractive-index filler capable of mass production.
IV. Reference for mass production market strategy (n=1.38–1.40).
(1) Organic phase: 60 wt%.
1. Fluorinated low-refractive-index resin, 35 wt% (base refractive index: 1.36).
2. IBOA 15 wt% (adjusts hardness and enhances adhesion).
3. EO2HDDA/DEGDMA 10 wt% (reduces viscosity, improves leveling properties).
(2) Reduced inorganic phase content: 35 wt%.
Hollow nanosilica (porosity: 40%).
(3) Additive system: 5 wt%.
1. Photoinitiator 184/TPO, 3 wt% (specialized for fluorinated systems; requires long-wavelength initiation).
2. Wetting and dispersing aid: 2 wt% (to prevent settling and agglomeration of hollow silica).
Final product specifications:
Refractive index: 1.38–1.40
Transmittance: ≥97%
Haze: <0.3%
Hardness: 2H–3H
V. Four Major High-End Application Scenarios (fully aligned with the high-end discount system).
① Optical anti-reflective AR coating.
Mobile phone cover plate, lens assembly, multi-layer coated PET optical film
Alternating high and low refractive index coating: high refractive index 1.67 + low refractive index 1.38
The single-sided reflectance can be reduced to below 0.8%.
② AR/VR optical lenses
Eliminating stray light, ghost images, and rainbow fringes while enhancing image sharpness makes this film an essential component for wearable optics devices.
③ High-end anti-fouling and anti-fog coating
The fluorine-based system inherently possesses ultra-low surface energy, offering both low light transmittance and hydrophobic, anti-fouling properties.
④ Optical lithography, optical waveguide substrate matching
By precisely controlling the height difference, a light-path confinement structure is constructed for applications in micro-and nano-optics as well as the fabrication of light-guiding structures.
VI. Three Key Technical Challenges in Low-Degradation UV Resin & Their Solutions
① Challenge 1: The lower the refractive index, the poorer the adhesion.
Reason: Fluorine has extremely low surface energy, making it difficult to wet the substrate.
solve:
Add a small amount of DEGDMA/TEGDMA to increase polarity;
Pre-coat the substrate with a primer; ensure that the proportion of fluorine monomer does not exceed the specified limit.
② Challenge 2: Hollow silicon is prone to cracking, and high doping levels can cause a sharp increase in viscosity.
Reason: Excessive shear in the hollow structure may lead to bore collapse and a rebound increase in the refractive index.
solve:
Low-speed dispersion + mild sanding;
Prioritize pre-dispersion using the low-viscosity EO2HDDA system.
③ Challenge 3: Low-refractive-index systems are prone to fogging and exhibit reduced light transmittance.
Causes: Poor packing compatibility and phase separation
solve:
Specialized fluorine-modified dispersant;
Strictly control the particle size distribution of hollow silicon.
VII. Summary: High refraction for light focusing, low refraction for light transmission—achieving a complete optical closed loop.
If the TiO₂ high-refractive-index resin (n₁.₆–₂.₀) is responsible for focusing, brightening, and concentrating light;
The fluorine-modified hollow silica low-refractive-index resin (n<1.4) is responsible for reducing reflection, enhancing light transmission, and suppressing glare.
Combining a high-index and a low-index material, along with a clustered and a transparent variant, this configuration constitutes the core UV optical material system for current displays, lenses, and AR optics.
Selection of the right grade from the UV curing adhesive range usually starts with drawings and service conditions. The companion piece on Understanding UV Viscosity in One Article Core sits alongside this guide, the the JOME adhesive manufacturer profile lists every family, and the contact JOME for project review handles enquiries.