UV Curing Research Articles

Water‐based UV curable hybrid urethane‐acrylates formed by acid–base interaction between tertiary amine containing polyurethane and acrylic acid for photocoating and ink applications

AbstractUrethane acrylate hybrids are commonly used in polyurethane dispersions (PUD). PUDs are key ingredients in UV curing applications and UV curing is widely used in coatings and inks. The preparation of PUDs involves many volatiles in the form of solvents and reagents that are also carried over in the UV curing step. This article reports a process, which totally eliminates these volatile components and additionally introduces many flexibilities. The process involves acid–base interaction between tertiary amine containing polyurethane and acidic vinyl monomer like acrylic acid forming polyurethane‐acrylate (PU‐AA) hybrids in water. The developed process also overcomes the prepolymer and “endcapping” approaches used in the preparation of PUDs that restrict the molecular weight of polyurethanes. Simultaneously, because of the prevalence of large number of vinyl components in the polymer backbone through the acid–base interaction, it functions as a multifunctional acrylate similar to the reactive diluents used in UV curing applications. Thus, it helps to increase the cross‐linking density of the UV cured substrates. In general, high crosslinking density helps to improve characteristics like hardness, scratch, solvent and stain resistance of coated substrates. The process has been demonstrated to form transparent and opaque coated substrates and cured inks. This development potentially helps to shift the process from an industrial activity to do‐it‐yourself domain and has implications for the development of components for 3D printing sustainably.

Fabrication of SiC(OAl) and SiC(Al) fibers by melt-spinning, UV curing, thermolysis and sintering of photo-sensitive polyvinylaluminocarbosilane

SiC fiber is an important structural material in high-temperature extreme environments and nuclear energy applications. Oxidation and electron irradiation are main curing methods for the fabrication of industrial SiC fibers. In this work, a photo-sensitive polyvinylaluminocarbosilane (PVACS) is facilely prepared by blending polyaluminocarbosilane (PACS) and 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane (D4Vi), which can be melt spun, cured by ultraviolet irradiation at room temperature. After thermal pyrolysis and sintering, the SiC(OAl) fibers with oxygen content of 8.84 wt% and C/Si ratio of 1.34, the SiC(Al) fibers with oxygen content of 0.29 wt% and C/Si ratio of 1.03 are achieved. The cured mechanism and the structural evolution from the precursor fiber to the final ceramic fibers is investigated. The results show that homopolymerization of D4Vi is the main curing mechanism in addition to the β-addition of hydrosilylation. Different from the typical oxidative curing, the oxygen in the fibers mainly comes from D4Vi. At about 800 ℃, the SiAlxOy phase, the SiCxOy phase and free carbon are formed. At 1200 ℃, the Al-C bonds possibly in Al4C3 are formed. At around 1600 ℃, Al may exist mainly in the form of Al4O4C, and the amorphous carbon phase changes into crystalline graphitic structure. Meanwhile, a lot of mesopores and macropores in the SiC(OAl) fibers are formed due to thermal decomposition of the SiCxOy phase. However, at 1800 ℃, the SiC(Al) fibers densify again due to the formation of Al2OC and Al4SiC4 phases, which also inhibit the growth of β-SiC and favor the formation of α-SiC.

Facile synthesis of UV-curable fluorosilicone polymers and coatings with good corrosive resistance on account of the reaction of disulfide bonds with vinyl groups

A new UV curing strategy is introduced into the curing field of fluorosilicone polymers. This strategy is predicated on the reaction of sulfur radicals generated from disulfide bonds with vinyl groups under the presence of UV light. Here, we engineered and synthesized a kind of novel fluorosilicone polymers (FS-SS) with disulfide bonds and vinyl groups. The disulfide bonds contained in FS-SS undergo photocleavage under ultraviolet irradiation, generating sulfide radicals, which can interact with vinyl groups to complete the curing reaction. Subsequently, the UV curing behavior of coatings on the basis of the novel polymers and photo-initiator 1173 was investigated by FT-IR spectroscopy and a possible UV-curable reaction mechanism based on disulfide bonds and vinyl groups was proposed. The results showed that curing reactions based on disulfide bonds and vinyl groups can reach a relatively high degree of reaction in a short period of time in terms of reaction rate. However, the lower conversion rate of the reaction may be due to the fact that the sulfur radicals generated by disulfide bonds are more inclined to form disulfide bonds rather than undergo addition reactions with vinyl groups. Subsequently, a series of fluorosilicone coatings with good optical transparency (transmittance above 90 %), good hydrophobicity (the lowest value of surface energy is 21.54 mN/m), lower roughness value (Ra values was in the region of 2.24 nm– 12.2 nm) and high temperature resistance were prepared by utilizing this curing strategy. Furthermore, the applicable experiment of fluorosilicone coatings to protect tinplate as anti-corrosive coatings was also performed. The corrosive resistance results formalize its practical value for possible application as preventive coatings.

AI-driven real-time failure detection in additive manufacturing

The optimisation of 3D printing parameters for manufacturing biomedical devices is an emerging interdisciplinary field that incorporates artificial intelligence techniques such as machine learning and deep learning. In this particular study, the focus is on the fabrication of biocompatible finger splints using digital light processing 3D printing technology, followed by UV curing, to evaluate their quality. By leveraging vibration data from printers, which cannot be captured through visual inspection of layer defects, this study aims to develop a predictive model for assessing the failures of printed parts. Here, a closed-loop detection system is proposed to identify failure phenomena in 3D resin printing, combining both cloud and edge computing technologies to effectively detect and address potential failures in the printing process.

The effect of post-ultraviolet light curing on the accuracy of direct-printed aligners: an in vitro study

Abstract Background/Objectives Direct-printed aligners have proven to be more cost effective and accurate. However, the post-curing process might affect their dimensional accuracy, leading to unwanted tooth movement. The present study aimed to investigate the effect of different post-curing durations on the location specific accuracy of direct-printed aligners. Method A stereolithography printer was used to produce 30 aligners using Dental LT V2 resin. The aligners were randomly assigned into 3 groups (n = 10 each) according to different post-ultraviolet light-curing durations: 0 min (No cure); 40 min or 60 min. The aligners in each group were then scanned and superimposed on certain landmarks to check for location specific deviations using a best fit algorithm. Discrepancies were assessed at 10 different points by one examiner at two different time intervals (0.25 mm was the clinically acceptable threshold limit). One way ANOVA and repeated measures ANOVA were applied for statistical analysis. Results Deviations were maximum in the ‘No cure’ group but were statistically insignificant (p-value > 0.05). The deviation values in the ‘40 and 60 min cure’ groups were comparable and statistically significant (p-value < 0.05), with maximum deviation noted in the anterior region. All values in the ‘40 and 60 min cure’ groups were within the clinically acceptable range. Conclusion Post-print ultraviolet light curing is a crucial step to ensure the rigidity of the direct-printed aligner. However, increasing the duration of light curing has little effect on aligner accuracy.

Performance on lapping quartz glass by UV curing fixed abrasive pad with Gr2O3-diamond composite abrasives

Performance on lapping quartz glass by UV curing fixed abrasive pad with Gr2O3-diamond composite abrasives

Evaluation of gelatin-based hydrogels for colon and pancreas studies using 3D in vitro cell culture.

Biomimetic 3D models emerged some decades ago to address 2D cell culture limitations in the field of replicating biological phenomena, structures or functions found in nature. The fabrication of hydrogels for cancer disease research enables the study of cell processes including growth, proliferation and migration and their 3D design is based on the encapsulation of tumoral cells within a tunable matrix. In this work, a platform of gelatin methacrylamide (GelMA)-based photocrosslinked scaffolds with embedded colorectal (HCT-116) or pancreatic (MIA PaCa-2) cancer cells is presented. Prior to cell culture, the mechanical characterization of hydrogels was assessed in terms of stiffness and swelling behavior. Modifications of the UV curing time enabled a fine tuning of the mechanical properties, which at the same time, showed susceptibility to the chemical composition and crosslinking mechanism. All scaffolds displayed excellent cytocompatibility with both tumoral cells while eliciting various cell responses depending on the microenvironment features. Individual and collective cell migration were observed for HCT-116 and MIA PaCa-2 cell lines, highlighting the ability of the colorectal cancer cells to cluster into aggregates of different sizes governed by the surrounding matrix. Additionally, metabolic activity results pointed out to the development of a more proliferative phenotype within stiffer networks. These findings confirm the suitability of the presented platform of GelMA-based hydrogels to conduct 3D cell culture experiments and explore biological processes associated with colorectal and pancreatic cancer.

Determination of curing times in an ultraviolet curing composites manufacturing process.

Determination of curing times in an ultraviolet curing composites manufacturing process.

Gloss Level, Type of Paper and Colour of HDF Boards Finished with the Energy-Saving Acrylic Paint System

The global drive to eliminate mercury is stimulating the development of LED lamps for UV curing of coatings. Despite its many advantages, the transition to this system in the furniture industry presents technological issues. This paper aimed to determine the impact of the paint line’s individual technological and process parameters on the coating’s optical properties, such as colour and gloss of furniture components made of white-coloured light-weight boards. Samples were prepared under the conditions of an industrial paint line using LED and traditional mercury lamps at the rate of 50 m/min. The colour was tested using the CIELAB system on a BYK GARDNER spectrophotometer, while the gloss was measured using the PICO GLOSS meter. Based on the data obtained, the optical parameters were found to be highly stable irrespective of the power drop in the LED lamps. The coordinates L*, b* and gloss G were affected by the amount of topcoat and basecoat, the number of coats, the mercury lamps’ power and the panel grinding programs used. The results of the tests showed that high L* and b* values could be achieved by increasing the number of overlays. This solution also ensures less basecoat and topcoat consumption, contributing to large material savings.

Rational design of waterborne biobased epoxy methacrylates using citric acid and epoxy soybean oil for UV-curable coatings

Waterborne biobased UV-curable coatings (WBUCs) with environmentally friendly, renewable and energy-saving characteristics have attracted increasing attention. However, waterborne epoxy soybean oil-based UV-curable resin is mainly synthesized by introducing a polyurethane acrylate segment, which involves the use of toxic isocyanates. It is highly desirable to develop a more environmentally friendly method to prepare waterborne epoxy soybean oil-based UV-curable coatings. In this work, a “green + green + green” method was provided to synthesize three kinds of epoxy methacrylates, in which a citric acid (CA)-derived functional precursor (GC) was used to modify epoxy soybean oil (ESO), hydrogenated bisphenol epoxy resin (HBPAEP), and bisphenol epoxy resin (BPAEP) via an epoxy ester reaction. After confirmation by FT-IR and 1H NMR, it was found that the obtained epoxy methacrylates contain abundant intrinsic hydroxyls and carboxyls and extrinsic hydroxyls by the epoxy ester reaction, thus endowing these epoxy methacrylates with excellent hydrophilicity, compatibility, and stability. Meanwhile, after UV curing, the obtained WBUCs exhibited superior adhesion and thermal and mechanical properties. Moreover, the differences in these performances were systematically studied for these WBUCs with different compositions. Our “green + green + green” method provides a novel and rational potential design for WBUCs with high biobased content and excellent performance.

Soybean oil‐based nanocomposites for dye adsorption: AESO‐chitosan‐graphene oxide synergy in water treatment

AbstractThis study presents the synthesis and characterization of a bio‐adsorbent (A‐C2‐G3) based on the acrylated epoxidized soybean oil (AESO) for the efficient removal of methylene blue (MB) dye from aqueous solutions. The adsorbent was synthesized by incorporating chitosan and nano graphene oxide into the AESO matrix, followed by crosslinking through the UV curing process. The effects of various parameters, including pH, contact time, initial dye concentration, adsorbent dosage, and ionic strength, on the adsorption performance were systematically investigated. The experimental data were best fitted by the Langmuir isotherm model, suggesting a monolayer adsorption process, with a maximum adsorption capacity of 263.87 mg g−1. The adsorption kinetics followed the pseudo‐second‐order model, indicating the significance of electron exchange between the adsorbate and adsorbent during the process. Three primary interaction mechanisms at the interface between MB and A‐C2‐G3 and the A‐C2‐G3 bio‐adsorbent were identified: electrostatic interactions, hydrogen bond formation, and π–π stacking. The reusability of the synthesized adsorbent was evaluated through a series of adsorption–desorption cycles, maintaining high adsorption capacities for up to three cycles. These findings highlight the potential of the AESO‐based bio‐adsorbent for effective MB dye removal from wastewater.

UV light leads to the formation of reduced graphene oxide and silver nanoparticles in waterborne coating

Ultraviolet (UV)-curable waterborne epoxy acrylic resin (EB) containing silver nitrate and graphene oxide (GO) was prepared. A new waterborne epoxy acrylate-based coating (rGO/AgNP/CEB) containing reduced graphene oxide (rGO) and silver nanoparticles (AgNPs) was obtained by the in situ crosslinking of EB and the reduction of GO and silver ion (Ag+) via UV curing. The experimental results showed that UV irradiation combined with glucose effectively reduced GO and Ag+ to rGO and AgNP. Moreover, AgNPs with a diameter of approximately 60 nm were uniformly distributed in the coating. This material can be used for the antifouling of the inner wall of fishponds in mariculture.

Synthesis of mace silver nanorod with particles and water-alcohol room-temperature-curing UV conductive ink

At present, the silver nanorods of UV conductive ink have the problems of easy agglomeration of silver nanorods, and slow curing speed. In this paper, firstly mace-like silver nanorods with inorganic particles were synthesized by using polycarbonate fibers as soft-templates, AgNO3 as silver source. The diameters and lengths of silver nanorods were 0.25–0.35 μm and 2.1–5.1 μm. There are many wolf-tooth particles (0.20–0.35 μm) on the silver nanorods which prevented the silver nanorods from reuniting. The obtained silver nanorods were not easy to agglomerate. The minimum resistance value of the coating could reach 1∼10Ω. Secondly, a kind of water-alcohol UV conductive ink with low heat treatment temperature (140 °C), fast drying and curing speed and water-alcohol system was prepared. Water-alcohol soluble P(AA-r-HEMA)-g-GMA was used as the prepolymer, glycidyl triethylenetetraamine hexamethacrylate (TGMA) was used as the monomer, and 907 and ITX were used as photoinitiators. The effects of the types and contents of different photoinitiators (907:1%–5%, ITX: 0.2 %∼1 %), species and contents of prepolymer (30 %∼50 %), the number and content of monomers with different functional groups (30 %∼50 %) on the UV-curing rate were studied. The curing rate was the fastest when the mass fraction of photoinitiator ITX was 0.4 %, the mass fraction of the prepolymer with 30 % GMA content was 50 % and the mass fraction of monomer TGMA was 50 %. The curing speed can reach 2–3 s, and the ink film surface was smooth without bubbles. At last, UV conductive ink was prepared by using the obtained water-alcohol UV curing system as the bonding material and mace-like silver nanorods as the conductive filler. The influence of heat treatment temperature and time on the conductive properties of the coating was explored. The optimal heat treatment temperature was 140 °C, and the heat treatment time was 30 min.

Photoinitiator-grafted polymer coating enable various hydrogels with strong resistance to both drying and swelling

Currently, diverse hydrogels with multiple functionalities have attracted considerable attention. However, due to poor adaptability in real-life application scenarios for example in drying air and underwater, the hydrogels developed to date have not yet realized most of their promising applications, particularly in flexible electronics. Herein, inspired by the process of preparing the outermost layer of sugar coating on Tanghulu, a traditional Chinese winter snack, we report a dipping-ultraviolet (UV) encapsulation method for affording hydrogels with excellent water retention and anti-swelling capacity. A photoinitiator-grafted polymer chain (PGPC) with UV curing capability is prepared by 4-benzoylphenyl acrylate (ABP) and hydrophobic monomers radical polymerization, which is uncrosslinked during synthesis. After dipping and UV irradiation, the PGPC on the polyacrylamide (PAAm) hydrogel surface is cross-linked by benzophenone (BP) chemistry to form a coating network. Furthermore, the PGPC-coated hydrogel PAAm demonstrates great anti-drying properties with a weight fraction of up to 0.85 ± 0.02 after 21 h at 50 °C and anti-swelling capacity with a weight fraction of down to 1.01 ± 0.01 after 120 h in deionized water. Benefiting from the BP chemistry, the versatility of this method is demonstrated using various hydrogels such as polyvinyl alcohol (PVA) and polyzwitterionic hydrogel. As a proof-of-concept, the coated-hydrogel-based sensor shows strong signals anti-interference ability in ambient air and underwater. This work provides a promising route for encapsulating different hydrogels endowing weak hydrogels with strong environmental adaptability.

To Shed Light on the UV Curable Coating Technology: Current State of the Art and Perspectives

The industrial application of UV curable coatings is being widely commercialized at a rapid pace with very diversified product markets. UV curing has existed for many years now, but the new commercial opportunities emerging for sustainable, and climate friendly technologies have driven demand for photo-curable coating systems. It is primarily attributed to its environmentally friendly solvent-free and energy-efficient method. Precedented UV light curable coatings are being commercialized and numerous lamp sources are being extensively studied. In such an era of predominant research evolving the UV curing technology horizon, we attempt to outline the state of the art, opportunities, and challenges. This contribution attempts to highlight, in a comprehensive way, sustainable UV coating on the basis of recent research advancements, existing challenges and prospective scope in this field. With a set of prerequisite foundational knowledge into UV curable coatings and mechanisms, the review has meticulously looked at the recent research advancements. This review contribution attempts to focus on three aspects: the known science behind UV curing coatings, coupled with the recent advancements, and future opportunities.

Radiation Curing of Phosphorus Telomer-Based Coatings Using UV LEDs or Medium-Pressure Mercury Lamp

In the presented study, UV LEDs (365 nm) or a medium-pressure mercury lamp (UV-ABC) were verified as UV radiation sources initiating the photocrosslinking process of varnishes based on novel photopolymerizable phosphorus (meth)acrylate oligomers. Coating formulations were composed of (meth)acrylic/styrene telomers with terminal P-atoms (prepared via a UV phototelomerization process) and different photoinitiators (HAPs, APOs, or APO blends). The kinetics of the UV crosslinking process of the coating formulations depending on UV irradiation and the UV range was investigated by the photo-DSC method. Moreover, the hardness of the varnishes and the conversion of double bonds using the FTIR method were tested. The photopolymerization rate and the photoinitiation index, depending on the type of photoinitiator, were as follows: APOs < APO blends < HAPs. However, the highest coating hardness results were obtained using the least reactive photoinitiator from the APO group, i.e., Omnirad TPOL, or a mixture of three different types of acylphosphine (Omnirad BL 750). The greater effectiveness of the above-mentioned APOs over HAP was also demonstrated when using a UV LED lamp at 365 nm with a low UV dose and UV irradiance, thanks to the presence of phosphoric acid diester in the coating composition, acting as both a telogen and an antioxidant.

Ultraviolet-thermal coupling cross-linked fabricate polymer/ceramic composite solid electrolyte for room temperature quasi solid state lithium ion batteries

Polymer-based electrolyte, as a key component of lithium ion solid state battery, has good adaptability to lithium metal anode, and has received extensive attention in recent years. However, the low conductivity, limited thermal stability and poor mechanical strength of polymer-based solid electrolytes restricting its commercial application. Herein, We reveal experimentally that the Polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP)/Li1.3Al0.3Ti1.7(PO4)3 (LATP) composite solid electrolyte can be prepared by means of ultraviolet and thermal coupling curing (UV-TC) process, and the electrolyte film has better electrochemical performance than that prepared by means of thermal curing (TC) process. Therefore, the carefully designed electrolyte film is efficiently prepared by UV-TC curing process to improve the specific capacity (152.34 mAhg−1), the rate performance (89.04 mAhg−1 at 1 C) and good cycle performance (92.3 % retention rate in 100 cycles at 0.1 C) at room temperature for Li||PVDF-HFP/LATP||LFP solid state battery. The ionic conductivity of the solid electrolyte film prepared by the UV-TC method (4.3 × 10−4 S cm−1) is more encouraging than that of the TC method (9.2 × 10−5 S cm−1). This work shows that the polymer/ceramic composite solid electrolyte films (CSEs) prepared by simple and efficient UV-TC method has great prospects in realizing high energy density and high safety room temperature quasi solid state lithium ion batteries.

3D printed epoxy/acrylate hybrid polymers with excellent mechanical and shape memory properties via UV and thermal cationic dual-curing mechanism

Fabricating shape memory polymers with complex configurations and high mechanical performance for application as structural materials remains a significant challenge. Here, an epoxy/acrylate hybrid material with remarkable mechanical properties and excellent shape memory performance is fabricated using vat photopolymerization printing technology through photo-thermal dual curing mechanism. The UV-curing component comprises of a polyurethane acrylate and a rigid active diluent to ensure robustness and toughness. Meanwhile, the thermal curing epoxy constituent utilizes a benzylanilinium salt as the cationic initiator for its storage and handling stability throughout the UV curing stage. The interpenetrating polymer network and the unique two-phase molecular microstructure impart the hybrid material with good shape memory and high mechanical properties. Many complex objects are fabricated using vat photopolymerization printing technology and employed in self-deploying antennas, intelligent mechanical grippers, and switches. Combining with excellent printability, mechanical and shape memory properties, the hybrid materials have great potential applications in various fields.

The effect of carbonyl components of printing substrates on the durability of UV thermochromic prints

Special effects on a printed product can increase consumer’s interest in a product and therefore lead to higher revenues in consumer industries. For that purpose, graphic industry introduced various technologies and materials that would have such an effect and enhance consumer-goods interaction. One of those solutions is thermochromic printing. Although bringing added value, thermochromic inks have some challenges in application due to their higher sensitivity, especially when exposed to UV light. Therefore, the goal of this work is to determine whether amount of the UV radiation during curing of UV thermochromic prints, as well as exposure after printing would degrade the thermochromic print on various substrates. UV thermochromic prints were made on three different paper printing substrates using the screen printing method and dried in a laboratory controlled unit. Synthetic paper, recycled paper containing 100 % recycled cellulose fibers and bulky voluminous paper were used as printing substrates. During the UV curing of the ink, no photooxidation of the prints occurred. Additional exposure of the prints to UV radiation (after the ink has hardened) leads to their photooxidative degradation, i.e., a change in the initial color. The obtained colour difference (ΔE) is increasing with the increase of the irradiation amount. The highest colour difference is on the synthetic paper while prints on two other substrates are more resistant to UV light. A print on synthetic paper photooxidizes the fastest due to the presence of most carbonyl groups in it. Generated free radicals promote the instability of prints on synthetic paper. Research has proven that when using synthetic paper or substrates with similar characteristics, care should be taken to accurately determine the amount of UV energy required for curing in order to prevent photodegradation of the ink. The results also show that to explain any degradation of prints, the chemical components of the paper needs to be taken into account, which is rarely done.

The Modification of Cotton Fabric by Silane Coupling Agent for Improving the Durability of UV Curing Ag@rGO Coating

The Modification of Cotton Fabric by Silane Coupling Agent for Improving the Durability of UV Curing Ag@rGO Coating