UV-cured nano-coatings combine UV-curing green technology with emerging nano-technology to make certain properties of coatings significantly improved.


Wei Jun et al. synthesized urethane terminated with NCO by using hexamethylene diisocyanate (HDI), N-methyldiethanolamine (MDEA) and 4,4'-dihydroxybenzophenone (DH-BP) as raw materials. The polymer is then grafted onto the surface of the nano-SiO 2 to obtain a nano-SiO 2 having a polyurethane structure.


A photocurable composite film was prepared by adding it to a urethane acrylate resin (PUA). Studies have shown that the introduction of polyurethane molecular chains on the surface of nano-SiO2 effectively reduces the agglomeration of nanoparticles in the matrix resin, improves the compatibility of the nanoparticles with the matrix resin, and improves the thermal stability and mechanical properties of the photocured film.


Xu Yuqing et al. prepared nano-SiO2/urethane acrylate (PUA) by grafting nano-silica (SiO2) onto the surface of hexamethylene diisocyanate (HDI) trimer and reacting with hydroxyethyl acrylate (HEA). Prepolymer.


The effects of nano-SiO2/PUA prepolymer doping amount on material flexibility, hardness, transparency, heat resistance and impact resistance were discussed. Studies have shown that when the ratio of the mass fraction of PUA/nano-SiO2 prepolymer is 60%, the comprehensive performance of the composite material is optimal.


WANG Xin et al. obtained a graphene-containing PUA nanocomposite by combining graphene nanosheets (F-GNS) functionalized with 3-methacryloxypropyltrimethyloxysilane with urethane acrylate.


The nanocomposite has a thermal degradation temperature of 16 ° C. When the F-GNS mass fraction reaches 1%, the storage modulus and glass transition temperature of the nanocomposite increase.


This is due to the covalent modification of graphene which improves the interaction between the F-GNS and PUA interfaces dispersed in the polymer matrix.


Dai Yuting used IPDI, polyether glycol, HEMA, DM-PA, GO (graphene oxide) as raw materials to obtain graphene-containing waterborne urethane acrylate prepolymer by in-situ polymerization.


It improves the wear resistance, aging resistance, mechanical properties, gas permeability and thermal stability, and also greatly reduces the electrical resistivity of the cured film, and can be used for conductive coatings.
 


 
YU Bin et al. incorporated self-made functionalized graphene oxide (FGO) into urethane acrylate (PUA) by UV curing technology (as shown in Figure 5), and characterized FGO/PUA nanocomposite coating by FTIR, XRD and TEM. Structural and morphological characteristics.


The results show that the FGO sheet is uniformly dispersed in the PUA matrix and forms a strong interfacial adhesion with PUA. This is because a crosslinked network is formed between FGO and PUA after UV curing. The introduction of FGO effectively enhances the thermal stability of the host polymer. Sex and mechanical properties.


D Kim et al. prepared a series of ZnO nanocomposites with different ZnO contents through UV curing system.


In order to ensure the good dispersion of ZnO nanoparticles in the PUA matrix, ZnO nanoparticles were modified by silane coupling agent. WAXD and SEM analysis showed that the surface-modified ZnO nanoparticles were uniformly dispersed in the PUA matrix.


Compared with pure PUA, the cured film hardness increased from 0.03 GPa to 0.056 GPa, and the elastic modulus increased from 2.75 GPa to 3.55 GPa. In addition, the hydrophobicity and thermal stability of the composite film were improved.


Due to the relatively high surface activity of nanomaterials, dispersing them into the coating matrix is a key technology for the application of nanomaterials in coatings.


J Lee et al. applied supercritical fluid (SCF) technology to the preparation of nanoparticles. The supercritical fluid has almost zero surface tension and high diffusion performance. It can be fully mixed with the substrate to maximize its performance. Solubility has recently attracted widespread attention.


2.6 Silicone modified urethane acrylate


Silicone-modified UV-curable PUA has the advantages of low surface tension, high weather resistance, hydrophobicity, chemical resistance, heat resistance, etc. It is incorporated into the silicone to modify the oligomer during the synthesis, giving the coating film good resistance. Heat, water resistance, mechanical properties.


Shi Jin et al. used trimethylolpropane (TMP) as the center and used N,N-dihydroxyethyl-o-carbamoylbenzoic acid and N,N-dihydroxyethyl-3-aminopropionate alone. The hyperbranched polymer (HBP-OH) was synthesized.


On this basis, a UV-curing hyperbranched photosensitive silicone urethane acrylate prepolymer was synthesized using hydroxyethyl acrylate (HEA), isophorone diisocyanate (IPDI) and alkylhydroxysilicone oil (SD9134) as raw materials. (HBPSUA), and discussed the influence of the synthesis route and the amount of catalyst on the reaction and product.


Studies have shown that, under the premise of maintaining the properties of the prepolymer silicone, it imparts good flexibility, wear resistance, high hardness and excellent chemical resistance, and can improve silicone and other acrylate monomers. And the miscibility of the prepolymer.


Wei Jun et al. used hexamethylene diisocyanate (HDI)/toluene-2,4-diisocyanate (TDI) and polyethylene glycol (PEG) to prepare a polyurethane prepolymer, and pre-polymerized the surface of nano-SiO2. Graft modification.


Then it was uniformly dispersed into PUA. The research shows that the thermal stability and mechanical properties of the hybrid coating can be significantly improved by adding modified nano-SiO2.


Zeng Jianwei et al. used different aliphatic diisocyanates, acrylic monomers, and alcohol hydroxyl terminated polysiloxanes as the main raw materials.


The stepwise synthesis method is used to first synthesize a silicone-modified polyurethane, introduce a hydrophilic group, and finally introduce an acrylic monomer. The catalyst is a mixture of dibutyl laurate and an organic carboxylic acid rare earth.


The mixture is refluxed at a certain temperature to optimize the reaction conditions, so that the prepared photocurable silicone modified waterborne urethane acrylate coating has good performances such as yellowing resistance and high hardness.


YU Yong et al. synthesized photosensitivity using hydroxyl terminated polysiloxane, polypropylene glycol (PPG-2000), isophorone diisocyanate (IPDI), 2-hydroxyethyl acrylate (HEA), hydroquinone (HQ). Silicon-containing urethane acrylate prepolymer (Si-IPDI-HEA).


Studies have shown that Si-IPDI-HEA has higher polymerization rate and double bond conversion than common acrylic monomer resin, and the introduction of siloxane into the prepolymer improves the thermal stability of the UV cured film and changes the microscopic The structure reduces its surface energy.
 


 
Fuyue et al. use hydroxyalkyl polysiloxane (Q4-3667), isophorone diisocyanate (IPDI), polypropylene glycol (PPG-2000), diethanolamine and β-hydroxyethyl acrylate (HEA) as raw materials. A silicone modified polyether urethane acrylate oligomer (Si5E5PUA) was prepared as shown in FIG.


Studies have shown that Si5E5PUA has good compatibility with acrylate monomers, and the double bond conversion rate in the system is over 90%, which has excellent photopolymerization performance and effectively increases the glass transition temperature of the cured film.


Hu Feiyan et al. To improve the heat resistance, water resistance and flexibility of urethane acrylate, an organosiloxane was synthesized by a two-step method using an excess of isophorone diisocyanate (IPDI), a polyester diol and an alkyl hydroxy silicone oil. Block modified polyurethane copolymer.


It is then blocked by an acrylic monomer to obtain a UV-curable silicone urethane acrylate prepolymer. The results show that when the mass fraction of hydroxypropyl polysiloxane (PDMS) is 5% to 7%, the elongation at break, heat resistance and hydrophobicity of the coating film are obviously improved.