High refractive index cationic photocurable optical resin composition and use thereof

Abstract

The application discloses a high-refractive cationic photocuring optical resin composition and application thereof, and relates to the technical field of photocuring materials.The cationic photocuring optical resin composition provided by the application meets the following conditions after being cured in a 2mm thick sample: nD is greater than or equal to 1.68 (preferably 1.68-1.70), Vd is 38-42, the volume shrinkage is less than or equal to 2%, the water absorption is less than or equal to 0.3wt%, and the yellowness index is less than or equal to 2.0.The cationic photocuring optical resin composition is suitable for the rapid curing and forming of thick pieces of lenses and prisms, has a wide equipment and process window, and is easy to mass produce.

Description

Technical Field

[0001] This invention relates to the field of photocurable materials technology, and in particular to a high-refractive-index cationic photocurable optical resin composition and its applications. Background Technology

[0002] With increasing environmental awareness and stricter environmental regulations in various countries, UV-curable materials are gradually replacing traditional solvent-based coatings due to their advantages such as solvent-free or low-solvent properties, fast curing speed, low volatile organic compounds, and good film performance. UV curing includes two mechanisms: free radical curing and cationic curing. Free radical curing is more widely used, but its application is limited by poor adhesion of the cured film to the substrate, strong oxygen inhibition effect, and unique film irritation. In contrast, cationic curing overcomes these disadvantages. Cationic curable optical resins exhibit less volume shrinkage after curing, and the cured film has strong adhesion to various substrates. Furthermore, there is no oxygen inhibition effect during curing, and the curing reaction is less likely to terminate, making it suitable for thick-film curing. Therefore, cationic curing has become a research hotspot in the field of radiation curing.

[0003] Cationic curing is insensitive to oxygen and has low shrinkage, but it is difficult to achieve a balance between refractive index and Abbe number in common epoxy systems. Cyclosulfide monomers can significantly increase nD, but yellowing and curing rate need to be optimized. How to achieve a balance between high nD and relatively high Vd through the synergy of monomer ratio, chain transfer agent and photoacid system is a pain point in the industry. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] Therefore, one of the main objectives of this invention is to provide a high-refractive-index cationic photocurable optical resin composition and its applications. The cationic photocurable optical resin composition provided by this invention, after curing in a 2mm thick sample, meets the following requirements: nD ≥ 1.68 (preferably 1.68~1.70), Vd 38~42, volume shrinkage ≤ 2%, water absorption ≤ 0.3wt%, and yellowness index ≤ 2.0. It is suitable for rapid curing and molding of thick sheets of lenses and prisms, has a wide equipment and process window, and is easy to mass-produce.

[0006] (II) Technical Solution

[0007] To achieve the above objectives, the present invention provides a cationic photocurable optical resin composition, comprising the following components by total mass: 50-70 wt% cyclic sulfide monomer, 15-30 wt% alicyclic epoxy resin, 1-5 wt% ethylene ether diluent, and 1.5-3.0 wt% anionic compound thioonium salt photoacid.

[0008] Cyclosulfide monomers provide a high refractive index base, but when used alone, they may cure slowly and the network may be brittle.

[0009] The introduction of alicyclic epoxy not only effectively increases the Abbe number and reduces yellowing, but its copolymerization with cyclic sulfur can also form a tougher interpenetrating network, improving mechanical properties.

[0010] A trace amount of ethylene ether, as a highly efficient chain transfer agent, cleverly controls the chain length and network crosslinking density of cationic polymerization, significantly reducing the internal stress generated during the curing of thick sheets. This is the key to achieving low shrinkage and high dimensional stability.

[0011] Ultimately, the combination of anionic photoacids resolved the contradiction between the response efficiency of single photoacids at 405nm and the inhibition of yellowing.

[0012] In one embodiment, the cyclic sulfur monomer contains an aromatic ring and has 1 to 5 cyclic sulfur groups.

[0013] In one embodiment, the cyclic sulfur monomer contains an aromatic ring and has two cyclic sulfur groups.

[0014] In one embodiment, the cyclic sulfur monomer includes bisphenol A type cyclic sulfur resin, bisphenol F type cyclic sulfur resin, aliphatic cyclic sulfur resin and / or organosilicon cyclic sulfur resin; preferably, the cyclic sulfur monomer is an organosilicon cyclic sulfur resin.

[0015] In one embodiment, the cyclic sulfur monomer accounts for 62 wt% of the total mass of the composition.

[0016] In one embodiment, the alicyclic epoxy resin comprises 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylate, 3,4-epoxycyclohexylcarboxylate-3',4'-epoxycyclohexylmethyl ester, 1,2-epoxy-4-vinylcyclohexane, bis(3,4-epoxycyclohexyl)adipate, dicyclopentadiene diepoxide, 1,4-cyclohexanediethanol diglycidyl ether, dicyclopentadiene dioxide, and / or 3,4-epoxycyclohexylethylene; preferably, the alicyclic epoxy resin is 3,4-epoxycyclohexylcarboxylate-3',4'-epoxycyclohexylmethyl ester.

[0017] In one embodiment, the alicyclic epoxy resin accounts for 20 wt% of the total mass of the composition.

[0018] In one embodiment, the vinyl ether type diluent includes butyl vinyl ether (BVE), 4-hydroxybutyl vinyl ether (HBVE), triethylene glycol divinyl ether (DVE-3), 1,4-cyclohexyldiethanol divinyl ether, long-chain alkyl vinyl ether, and / or vinyl ether; preferably, the vinyl ether type diluent is vinyl ether.

[0019] In one embodiment, the vinyl ether diluent accounts for 2 wt% of the total mass of the composition.

[0020] In one embodiment, the anionic compound thioonium salt photoacid comprises bis(trifluoromethanesulfonyl)imide and hexafluorophosphate.

[0021] In one embodiment, the bis(trifluoromethanesulfonyl)imine (NTf) 2- ) and hexafluorophosphate (PF6) 6- The molar ratio of ) is (2~4):1.

[0022] In one embodiment, the anionic compound thioonium salt photonic acid accounts for 2.5 wt% of the total mass of the composition.

[0023] During the curing process, the cyclic sulfur / epoxy ring-opening polymerization occurs under photoacidity, and ethylene ether acts as a chain transfer agent to regulate the network crosslinking density and suppress stress peaks; mixed anions (NTf) 2- / PF 6- Improve the response and dark reaction efficiency at 405nm.

[0024] In one embodiment, the cationic photocurable optical resin composition further includes 0.1 to 0.5 wt% of a leveling agent and / or a stabilizer.

[0025] In one embodiment, the cationic photocurable optical resin composition specifically comprises, by total mass: 50-70 wt% silicone cyclosulfide resin, 15-30 wt% 3,4-epoxycyclohexylcarboxylic acid-3',4'-epoxycyclohexylmethyl ester, 1-5 wt% vinyl ether, and 1.5-3.0 wt% anionic compound thioonium salt photoacid.

[0026] In one embodiment, the cationic photocurable optical resin composition specifically comprises, by total mass: 62 wt% silicone cyclosulfide resin, 20 wt% 3,4-epoxycyclohexylcarboxylic acid-3',4'-epoxycyclohexylmethyl ester, 2 wt% vinyl ether, and 2.5 wt% anionic compound thioonium salt photoacid.

[0027] In one embodiment, the cationic photocurable optical resin composition specifically comprises, by total mass: 62 wt% silicone cyclosulfide resin, 20 wt% 3,4-epoxycyclohexylcarboxylic acid-3',4'-epoxycyclohexylmethyl ester, 2 wt% vinyl ether, 2.5 wt% anionic compound thioonium salt photoacid, and 0.5 wt% additives.

[0028] In another aspect, the present invention provides the use of the above-described cationic photocurable optical resin composition in the preparation of optical elements.

[0029] In another aspect, the present invention also provides an optical element prepared from the above-described photocurable optical resin composition.

[0030] In one embodiment, the optical element includes a convex lens, a concave lens, a right-angle prism, a beam splitter, a bandpass filter, a neutral density filter, a diffraction grating, and / or a holographic recording medium.

[0031] (III) Beneficial Effects

[0032] This invention provides a high-refractive-index cationic photocurable optical resin composition and its application. Compared with the prior art, it has the following advantages:

[0033] 1. The cationic photocurable optical resin composition provided by the present invention, after curing in a 2mm thick sample, satisfies the following: nD≥1.68 (preferably 1.68~1.70), Vd38~42, volume shrinkage≤2%, water absorption≤0.3wt%, and yellowness index≤2.0. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a schematic diagram of the ring-opening polymerization of cyclic sulfur / epoxy and the chain transfer mechanism of ethylene ether.

[0036] Figure 2 It is NTF 2- With PF 6- The effect of anion ratio on nD / Vd and yellowness.

[0037] Figure 3 It is a comparison of the haze / transmittance of thick film with the control. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] Terms and Definitions

[0040] As used in this article, “containing,” “having,” or “including” includes “containing,” “mainly composed of,” “substantially composed of,” and “composed of”; “mainly composed of,” “substantially composed of,” and “composed of” are subordinate concepts of “containing,” “having,” or “including.”

[0041] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, and the reagents, methods and equipment used are conventional reagents, methods and equipment in this technical field.

[0042] Example 1: Preparation of anionic compound thionium salt photoacid:

[0043] 1.1. Raw materials:

[0044] Triarylsulfonium salt-NTf 2- (Commercial product, commonly 50wt% soluble in PC / PGMEA);

[0045] Triarylsulfonium salt-PF 6- (Commercial product, commonly 50wt% soluble in PC / PGMEA);

[0046] Dry solvent (PC, PGMEA, or anhydrous acetonitrile), moisture content ≤300ppm; brown bottle, nitrogen protection.

[0047] 1.2. Calculation and Weighing:

[0048] Measure the ratio using "molar number of anions" (2~4:1). If it is a solution-grade product, calculate the solid content and active content before weighing.

[0049] For example, to prepare 100g of a photosensitive mother liquor (4:1) with a solid content of 50wt%: NTf was calculated based on anion equivalent. 2- The corresponding thionium salt solution accounts for approximately 80% of the total active equivalent, PF 6- Approximately 20% is allocated to this component, with the remainder being solvent to bring the total solids content to the target level.

[0050] 1.3. Compound preparation steps:

[0051] Add the two thionium salt solutions to the dry solvent at 25-40 °C under nitrogen atmosphere, and stir for 30-60 min until completely transparent. If necessary, adjust the solid content to 40-60 wt% by vacuum rotary evaporation, filter through 0.20 μm PTFE, dry under -0.09 MPa vacuum at 40-50 °C for 4-8 h, and store in a sealed, light-protected container.

[0052] 1.4. Quality Control:

[0053] Moisture content ≤300ppm (Karl Fischer); anion molar ratio (19F NMR / ion chromatography) within ±5% of the target value; transparent appearance, low YI. When using, add the mother liquor directly to the resin according to the formulation (e.g., 2.5wt% in B2), stir evenly at 40℃, degas and filter before use.

[0054] PF 6- Salt has high acid production efficiency, but yellowing and haze are relatively high at 405nm; NTf 2- Salt has low color and fog but a slightly slower response. Mix in a 2-4:1 ratio ( Figure 2 The shaded area achieves the lowest haze and lower yellowing during thick film curing. Figure 3 () is superior to pure PF 6- (Comparative Example 2 showed a significant increase in YI / haze).

[0055] Example 2 Preparation of cationic photocurable optical resin composition 1:

[0056] Composition: Organosilicon cyclosulfide resin (refer to patent CN102219905A) 58wt%, 3,4-epoxycyclohexylcarboxylic acid-3',4'-epoxycyclohexylmethyl ester 25wt%, vinyl ether 3wt%, anionic compound thioonium salt photoacid (NTf) 2- :PF 6- =3:1) 2.2wt%.

[0057] Composition curing: The above compounds are mixed and then cured using light with wavelengths of 365 nm and 405 nm and an intensity of 10 mW / cm². 2 The composite light-irradiated resin mixture was cured into a gel by 20 min and then subjected to heat curing treatment, i.e., heat treatment at 90℃ for 2 h and then annealing at 60℃ for 0.5 h.

[0058] Reaction mechanism such as Figure 1 As shown, cyclic sulfur / epoxy undergoes ring-opening polymerization under photoacid irradiation, with ethylene ether acting as a chain transfer agent to regulate network crosslinking density and suppress stress peaks; mixed anions (NTf) 2- / PF 6- Improve the response and dark reaction efficiency at 405nm.

[0059] Example 3 Preparation of cationic photocurable optical resin composition 2 (B2):

[0060] Composition: Organosilicon cyclosulfide resin (refer to patent CN102219905A) 62wt%, 3,4-epoxycyclohexylcarboxylic acid-3',4'-epoxycyclohexylmethyl ester 20wt%, vinyl ether 2wt%, anionic compound thioonium salt photoacid 2.5 (NTf) 2- :PF 6-=4:1) wt%, and BYK-UV-3510 0.25wt%, BYK-1790 0.05wt%, Irganox-1010 0.15wt%, (optional) nonionic polyether modified polysiloxane antifogging additive 0.05wt%.

[0061] Composition curing: Same as in Example 2.

[0062] Example 4: Preparation of cationic photocurable optical resin composition 3:

[0063] Composition: Organosilicon cyclosulfide resin (refer to patent CN102219905A) 55wt%, 3,4-epoxycyclohexylcarboxylic acid-3',4'-epoxycyclohexylmethyl ester 28wt%, vinyl ether 4wt%, anionic compound thioonium salt photoacid (NTf) 2- :PF 6- =4:1) 2.0wt%, and BYK-UV-3510 0.35wt%, BYK-1790 0.10wt%, Irganox-1010 0.35wt%, (optional) nonionic polyether modified polysiloxane antifogging additive 0.20wt%.

[0064] Composition curing: Same as in Example 2.

[0065] Example 5 Preparation of cationic photocurable optical resin composition 4 (low-cyclic sulfur):

[0066] Composition: Organosilicon cyclosulfide resin (refer to patent CN102219905A) 48wt%, 3,4-epoxycyclohexylcarboxylic acid-3',4'-epoxycyclohexylmethyl ester 25wt%, vinyl ether 3wt%, anionic compound thioonium salt photoacid (NTf) 2- :PF 6- =3:1) 2.2wt%.

[0067] Composition curing: Same as in Example 2.

[0068] Example 6 Cationic photocurable optical resin composition 4 (pure PF) 6- Preparation of )

[0069] Composition: 58wt% organosilicon cyclosulfide resin (refer to patent CN102219905A), 25wt% 3,4-epoxycyclohexylcarboxylic acid-3',4'-epoxycyclohexylmethyl ester, 3wt% vinyl ether, 2.2wt% anionic triarylsulfonium salt, and 0.20wt% BYK-UV-3510, 0.05wt% BYK-1790, and 0.15wt% Irganox-1010.

[0070] Composition curing: Same as in Example 2.

[0071] The refractive index (nD), Abbe number (Vd), haze, volume shrinkage rate, and residual acid of the cured optical elements in Examples 2-6 were measured respectively.

[0072] The test results are shown in Table 1:

[0073] Table 1

[0074]

[0075] Note: Examples 2 / 3 / 4 correspond to B1 / B2 / B3 respectively; Example 5 is a low-cyclic sulfur control; Example 6 is pure PF. 6- Comparison.

[0076] like Figure 2 As shown, using pure PF 6- While showing no significant disadvantage in refractive index (1.682) and Abbe number (39.8), its yellowness index (YI) deteriorated sharply from 1.9 to 3.5 (p<0.001). Furthermore, its haze also increased significantly from 0.27% to 0.85%, indicating a decrease in internal curing uniformity and increased light scattering in the 2 mm thick sample. These results confirm that the compound anionic system of this invention plays an indispensable and crucial role in suppressing yellowing and ensuring the optical quality of thick films.

[0077] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0078] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications 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 the present invention.

Claims

1. A cationic photocurable optical resin composition, characterized by comprising: The composition comprises the following components by total mass of the composition: 50-70 wt% of cyclic sulfur monomer, 15-30 wt% of alicyclic epoxy resin, 1-5 wt% of vinyl ether diluent, and 1.5-3.0 wt% of anionic complex sulfonium salt photoacid; The cyclic sulfur monomer contains aromatic rings and has 1-5 cyclic sulfur groups; The alicyclic epoxy resin comprises 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexyl carboxylate, 3,4-epoxycyclohexyl carboxylic acid-3',4'-epoxycyclohexyl methyl ester, 1,2-epoxy-4-vinyl cyclohexane, bis(3,4-epoxycyclohexyl) adipate, dicyclopentadiene diepoxide, 1,4-cyclohexane dimethanol diglycidyl ether, dicyclopentadiene dioxide, and / or 3,4-epoxycyclohexyl ethylene; The anionic complex sulfonium salt photoacid comprises triaryl sulfonium bis(trifluoromethylsulfonyl) imide salt and triaryl sulfonium hexafluorophosphate salt; The molar ratio of the triaryl sulfonium bis(trifluoromethylsulfonyl) imide salt to the triaryl sulfonium hexafluorophosphate salt is (2-4):

1.

2. The cationic photocurable optical resin composition according to claim 1, characterized by The cyclic sulfur monomer comprises bisphenol A type cyclic sulfur resin, bisphenol F type cyclic sulfur resin, aliphatic cyclic sulfur resin, and / or silicone cyclic sulfur resin.

3. The cationic photocurable optical resin composition according to claim 2, characterized by The cyclic sulfur monomer is silicone cyclic sulfur resin.

4. The cationic photocuring optical resin composition according to claim 1, characterized in that, The alicyclic epoxy resin is 3',4'-epoxycyclohexyl methyl ester of 3,4-epoxycyclohexyl carboxylic acid.

5. The cationic photocuring optical resin composition according to claim 1, characterized in that, The vinyl ether diluent comprises butyl vinyl ether, 4-hydroxybutyl vinyl ether, triethylene glycol divinyl ether, 1,4-cyclohexyl dimethanol diethyl vinyl ether, long-chain alkyl vinyl ether, and / or vinyl ether.

6. The cationic photocurable optical resin composition according to claim 5, characterized by The vinyl ether diluent is vinyl ether.

7. The cationic photocuring optical resin composition according to claim 1, characterized in that, The cationic photo-curable optical resin composition further comprises 0.1-0.5 wt% of leveling agent and / or stabilizer.

8. Use of the cationic photo-curable optical resin composition according to any one of claims 1-7 in the preparation of an optical element.

9. An optical element, characterized by, Prepared from the cationic photo-curable optical resin composition according to any one of claims 1-7.

10. The optical element according to claim 9, characterized by The optical element comprises convex lens, concave lens, right-angle prism, light-splitting prism, band-pass filter, neutral density filter, diffraction grating, and / or hologram recording medium.

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