UV curing resin and preparation method thereof

Abstract

The invention relates to the field of resin, in particular to UV curing resin and a preparation method thereof, and the UV curing resin comprises the following raw materials in parts by weight: 30-50 parts of NEBA, 50-70 parts of IBOA, 1-5 parts of a photoinitiator and 0.1-2 parts of nano silicon dioxide dispersion liquid. NEBA and IBOA are combined in a chemical copolymerization mode, a rigid-flexible synergistic cross-linked network is constructed, the prepared finished product has high cross-linking density, ultralow shrinkage rate and excellent optical performance, indexes such as hardness, solvent resistance and light transmittance are remarkably superior to those of products in the existing market, and the product is suitable for the fields of precise optical elements, electronic packaging, automobile coatings and the like and has wide application prospects. The finished product can be directly applied to existing UV coating equipment, extra investment is not needed, and the process compatibility is high.

Description

Technical Field

[0001] This invention relates to the field of resins, specifically a UV-curable resin and its preparation method. Background Technology

[0002] Resin generally refers to an organic polymer that softens or melts when heated, tends to flow under external force when softened, and is solid, semi-solid, or sometimes liquid at room temperature. UV-curable resin is a common type of resin.

[0003] Existing UV-curable resins typically suffer from the following problems: 1. High volumetric shrinkage (usually greater than 5%): Traditional acrylate resins (such as IBOA) shrink during curing due to the rearrangement of molecular chain segments, affecting the dimensional stability of precision devices (such as optical lenses and chip packaging). 2. Insufficient crosslinking density: The network structure formed by the polymerization of a single monomer is prone to defects, resulting in poor solvent resistance and high-temperature resistance. 3. Limited performance: Current technologies usually involve physically mixing different monomers (such as IBOA and ordinary acrylates), making it difficult to achieve synergistic optimization of crosslinking density and shrinkage rate. Summary of the Invention

[0004] To achieve the above objectives, the present invention aims to provide a UV-curable resin that can solve the problems existing in the prior art. The present invention provides the following technical solution: A UV-curable resin comprising the following raw materials in parts by weight: 30-50 parts NEBA (norborneol acrylate), 50-70 parts IBOA (isoborneol acrylate), 1-5 parts photoinitiator, and 0.1-2 parts nano silica dispersion.

[0005] As a further aspect of the present invention, the photoinitiator is a TPO-L or 819 type photoinitiator.

[0006] As a further aspect of the present invention, the molar ratio of NEBA to IBOA is 1:1.5-1:2.5.

[0007] As a further aspect of the present invention: the particle size of the nano silica in the nano silica dispersion is 20-50 nm, and the surface of the nano silica is modified by a silane coupling agent.

[0008] A method for preparing a UV-curable resin includes the following steps: (1) Mix NEBA and IBOA in proportion and stir at 40-60 degrees Celsius to form a homogeneous prepolymer; (2) Add photoinitiator and nano silica dispersion to homogeneous prepolymer, and ultrasonically disperse for 10-20 minutes to obtain semi-finished product; (3) The semi-finished product is coated on the substrate and then cured with a UV light source to obtain the finished product, which has a dense cross-linked film layer.

[0009] As a further aspect of the present invention, the frequency of ultrasonic dispersion is 18-50KHz.

[0010] As a further aspect of the present invention, ultrasonic dispersion is carried out under light-protected conditions.

[0011] As a further aspect of the present invention: the UV light source is a 365nm UV light source under nitrogen protection, and the curing energy is 500-1000mJ / cm². 2 .

[0012] Compared with the prior art, the beneficial effects of the present invention are: This invention combines NEBA and IBOA through chemical copolymerization to construct a rigid-flexible synergistic crosslinking network. The resulting product exhibits high crosslinking density, ultra-low shrinkage, and excellent optical properties. Its hardness, solvent resistance, and light transmittance are significantly superior to existing products on the market, demonstrating outstanding overall performance. It is suitable for applications such as precision optical components, electronic packaging, and automotive coatings. The finished product can be directly applied to existing UV coating equipment without additional investment, and it has strong process compatibility. Detailed Implementation

[0013] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and 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.

[0014] In this invention, NEBA is a rigid monomer, providing a rigid cyclic structure and inhibiting shrinkage; IBOA is a flexible monomer, imparting flexibility and providing high refractive index and reactivity. Utilizing the steric hindrance effect of the norbornene rigid ring of NEBA and the isobornene group of IBOA, an interpenetrating network (IPN) structure is formed. During curing, the movement of molecular chain segments is restricted, thereby reducing the shrinkage rate by more than 90%. The difference in copolymerization rate (Kp ratio 1:3) between the norbornene double bond of NEBA and the acrylate double bond of IBOA enables gradient crosslinking, improving mechanical strength (hardness not less than 4H). Filling the network gaps by in-situ dispersing nano-silica further reduces the shrinkage rate and improves scratch resistance.

[0015] The finished product of this invention achieves the following performance breakthroughs: 1. Ultra-low volume shrinkage rate, not exceeding 0.5%, suitable for non-destructive molding of micron-scale optical devices (such as AR / VR lenses). 2. High cross-linking density, with a gel content of not less than 95%. 3. Excellent optical properties, with a refractive index of 1.52-1.55 and a light transmittance greater than 92%.

[0016] The specific implementation of the present invention will be described in detail below with reference to specific embodiments. Example

[0017] Raw materials: 40 parts NBEA, 60 parts IBOA, 3 parts TPO-L and 1 part nano silica dispersion (nano silica with a particle size of 30nm).

[0018] Curing conditions: 365nm LED light source, energy 800mJ / cm² 2 .

[0019] Comparative example: Pure IBOA.

[0020] The finished product of Example 1 and the comparative example were subjected to performance tests, and the test results are shown in Table 1.

[0021] Table 1 Performance Results index Example 1 Comparative Example Volume shrinkage rate 0.45% 5.2% gel content 97.3% 89.5% Refractive index (589nm) 1.54 1.53 hardness 4H 2H Wipe with ethanol (100 times) No shedding Surface blur As can be seen from Table 1, the volume shrinkage rate of Example 1 (0.45%) was reduced by 91.3% compared with the control group (5.2%), proving that the NEBA / IBOA / SiO2 system achieved shrinkage suppression through the ring-opening expansion of norbornene and the filling of nanoparticles.

[0022] Gel content: Example 1 (97.3%) was significantly higher than that of the comparative example (89.5%), reflecting that the gradient crosslinking network (NEBA flexible crosslinking + IBOA rigid monomer) and SiO2 interfacial bonding enhanced the crosslinking density.

[0023] Refractive index: Example 1 (1.54) is slightly higher than that of the comparative example (1.53), indicating that the rigid ring of IBOA and the modified SiO2 synergistically improve the refractive index (in line with the prediction of the Lorentz-Lorenz equation).

[0024] Hardness and solvent resistance: The pencil hardness increased from 2H to 4H, which is attributed to the rigid groups of IBOA and the physical reinforcement of SiO2; The fact that 100 ethanol wipes resulted in no peeling versus a blurred surface demonstrates that the dense cross-linked network and the SiO2 interface effectively block solvent penetration. In summary, Example 1 achieves a generational leap in three dimensions: shrinkage (91%↓), mechanical strength (hardness grade 2↑), and durability (solvent resistance), proving that the NEBA / IBOA / SiO2 system provides a complete solution for the next generation of photocurable resins.

[0025] Example 2 Five parts of fluorinated acrylate (HEFA) were added to the product of Example 1 for copolymerization. The temperature resistance of the products of Example 1 and Example 2 were tested, and the results are shown in Table 2.

[0026] Table 2 Temperature resistance performance of Examples 1 and 2 Performance indicators Example 1 Example 2 Increase Test Standards TGA 5% temperature of weight loss (°C) 172 180 +8℃ <![CDATA[ASTM E1131 (N2)]]> Heat distortion temperature (°C) 152 168 +16℃ ISO 75-2 (1.8MPa) Coefficient of linear expansion (ppm / ℃) 58 41 -29% ASTM D696 As can be seen from Table 2, the temperature resistance of the product in Example 2 is improved to 180 degrees Celsius (5% TGA weight loss), which is especially suitable for lens packaging scenarios of LiDAR.

[0027] Performance tests were conducted on the product of Example 1 and competing products in the market, and the results are shown in Table 3.

[0028] Table 3 Performance of Example 1 and Market Competitors Performance indicators Example 1 Market competitors Increase Test Standards Curing shrinkage rate (%) 18 5.2 -65% ISO 3521 Pencil hardness 4H 2H +200% ASTM D3363 Transmittance (550nm, %) 99.3 97.6 +1.7% ASTM D1003 Ethanol-resistant (number of wipes) >200 80 >150% GB / T 23989-2009 Crosslinking density (mol / cm3x10-4) 8.07 3.2 +172% Swelling method (DMA determination) As can be seen from Table 3, the product performance of Example 1 is superior to that of competing products on the market.

[0029] The product from Example 1 was used in automotive headlight coatings, and its performance was verified. The verification results are shown in Table 4.

[0030] Table 4 Validation Results Test Project Results of Example 1 Industry requirements: AE < 2.0 Xenon lamp aging (1000h) ΔE<0.8 No cracks (Grade B) Impact resistance of crushed stone No peeling (Grade A) No cracks Low-temperature bending (-40°C) No cracks Level 1 Adhesion (cross-cut test) Level 0 Industry requirements: AE < 2.0 As can be seen from Table 4, the product of Example 1 meets the product requirements when applied to automotive headlight coatings.

[0031] It should be noted that, in this invention, unless otherwise explicitly specified and limited, the terms "fixed," "set," etc., should be interpreted broadly. For example, they can refer to welded connections, bolted connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0032] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A UV-curable resin, characterized in that, It includes the following raw materials in parts by weight: 30-50 parts NEBA, 50-70 parts IBOA, 1-5 parts photoinitiator, and 0.1-2 parts nano silica dispersion.

2. The UV-curable resin according to claim 1, characterized in that, The photoinitiator is a TPO-L or 819 type photoinitiator.

3. The UV-curable resin according to claim 1 or 2, characterized in that, The molar ratio of NEBA to IBOA is 1:1.5 to 1:2.

5.

4. The UV-curable resin according to claim 1, characterized in that, The nano-silica dispersion contains nano-silica with a particle size of 20-50 nm, and the surface of the nano-silica is modified with a silane coupling agent.

5. A method for preparing a UV-curable resin, characterized in that, Includes the following steps: (1) Mix NEBA and IBOA in proportion and stir at 40-60 degrees Celsius to form a homogeneous prepolymer; (2) Add photoinitiator and nano silica dispersion to homogeneous prepolymer, and ultrasonically disperse for 10-20 minutes to obtain semi-finished product; (3) The semi-finished product is coated on the substrate and then cured with a UV light source to obtain the finished product.

6. The method for preparing the UV-curable resin according to claim 5, characterized in that, The frequency of ultrasonic dispersion is 18-50KHz.

7. The method for preparing the UV-curable resin according to claim 5 or 6, characterized in that, The UV light source is used under nitrogen protection with a 365nm UV light source, and the curing energy is 500-1000mJ / cm². 2 .