Preparation and characterization of sol–gel derived UV-curable organo-silica–titania hybrid coatings

In this work, UV-curable organic–inorganic hybrid coatings based on cycloaliphatic epoxyacrylate were prepared by sol–gel technique. Acid catalyzed solutions of tetraethylorthosilane (TEOS) containing Ti:acac complex were used as an inorganic precursors. UV-curable, transparent hybrid coating materials were applied on plexiglass substrates and their coating performance was investigated by the analyses of various tests such as hardness, gloss, cross-cut adhesion tests, stress–strain test and optical transmission. The mechanical measurements showed that, the tensile properties of coatings underwent an abrupt change from a brittle to a tough material when the inorganic part was incorporated into the cycloaliphatic epoxy acrylate based organic network. UV–vis transmission spectroscopy results indicated that the hybrid materials with high titanium content have good transparences. The thermal behaviour of the coatings was also evaluated. It is observed that the thermal stability of the hybrids is enhanced with incorporation of sol–gel precursor.     

光固化涂料用低粘度环氧丙烯酸酯的研究

采用双羟基化合物与环氧树脂进行反应,制取低粘度改性环氧树脂,然后用丙烯酸酯化,制得光固化涂料用低粘度环氧丙烯酸酯。研究了催化剂类型和用量对环氧树脂改性反应,以及不同结构、不同链长双羟基化合物和双羟基化合物与环氧树脂当量比对环氧丙烯酸酯粘度及其配制的光固化涂料的性能影响。确定了环氧树脂改性反应和丙烯酸酯化反应的最佳条件。     

High-performance waterborne UV-curable polyurethane dispersion based on thiol–acrylate/thiol–epoxy hybrid networks

Synthesis, characterization, and film performance of waterborne thiol–acrylate/thiol–epoxy hybrid coatings are highlighted in this article. A dimer acid-modified epoxy (DME) polyol, containing both hydroxyl and epoxy functional groups, was prepared by reacting epoxy resin (EEW = 190 g/equi) with dimer fatty acid at 2:1 molar ratio. Further, a base UV-curable polyurethane acrylate dispersion (UV-PUD), with a pendant epoxy functional group, was prepared by reacting polyol (DME), isophorone diisocyanate, and dimethylol propionic acid and end-capped with hydroxyethyl methacrylate with subsequent dispersion in water. Prepared intermediates were characterized for the parameters relevant to the study by physical, spectroscopic, and chemical methods. UV-curable thiol–acrylate/thiol–epoxy hybrid coatings were prepared by blending UV-PUD with trimethylolpropane tris(3-mercaptopropionate) (TMPMP) at four different thiol ratios (0, 0.3, 0.6, and 1.0) with respect to acrylate/epoxy groups. Cured films of the hybrid coating were identified by FTIR spectroscopy. The impact of thiol ratio on film performance was evaluated in terms of mechanical, chemical, thermal, and coating properties. The gel content measurements confirm that the addition of TMPMP increased the double bond conversion along with the epoxy group. Evaluation of cured samples shows the significant improvement in storage modulus, glass transition temperature, tensile strength, and hardness with increase in thiol ratio. The cured films possessed excellent water and acid resistance (<4%) even after 28 days of immersion. Moreover, the notable improvement was alkali resistance of cured films, i.e., as thiol ratio was increased from 0 to 1, weight loss in alkaline environment deceased from 49.5 to 4.5% after 28 days. Better properties of the thiol–acrylate/thiol–epoxy hybrid films will allow it as a potential application in low-volatile high-performance coatings.     

紫外光固化环氧丙烯酸酯涂料的制备及耐蚀性能研究

以E-51环氧树脂和丙烯酸为原料合成出光敏性环氧丙烯酸酯低聚物,制备了不同组成的紫外光固化涂料.合成产物的红外光谱分析结果表明,光敏性碳碳双键基团被引入到环氧树脂结构中;固化后涂层的红外表征结果表明,碳碳双键C=C的特征吸收峰消失,涂层固化较完全.在无水乙醇、5%NaOH和5%H2SO4溶液中的浸泡实验以及在3.5%NaCl溶液中的电化学阻抗谱测量结果表明,涂层具有较好的耐蚀性,其耐蚀性随着涂料中环氧丙烯酸酯含量的增加,呈先提高后下降的趋势.当环氧丙烯酸酯含量为40%,二缩三丙二醇双丙烯酸酯含量为50%时,所得涂层的耐蚀性最佳.     

Preparation and properties of novel high performance UV-curable epoxy acrylate/hyperbranched polysiloxane coatings

Novel high performance UV-curable coatings based on epoxy acrylate (EA) oligomer and hyperbranched polysiloxane (HPSi) were prepared, the effect of HPSi on the processing of uncured EA/HPSi system and integrated performance of cured resins is evaluated. Results show that a small addition of HPSi can greatly decrease the viscosity of EA oliogmer, while the viscosity almost does not reduces as the content of HPSi continuously increases owing to the interaction between HPSi and EA oligomer. The integrated performance of cured resins is closely related with the content of HPSi, those resins with suitable contents of HPSi have significantly improved toughness and stiffness as well as thermal and moisture resistance. The origin of all these changes in macro-performance are investigated and proved to be resulted from the variety in the chemical structure and crosslinking density induced by the addition of HPSi. These attractive features of EA/HPSi resins suggest that HPSi is an effective multi-functional diluent for UV-curable EA resin, and the method proposed herein is a new approach to develop high performance UV-curable coatings, solvent-free resins, etc., for cutting-edge industries.     

Boron containing UV-curable epoxy acrylate coatings

In the present work boron acrylate monomer was synthesized by esterification reaction. UV-curable boron containing epoxy acrylate coatings were prepared and applied on plexiglass substrates to obtain thermally and mechanically stable coatings. The physical and mechanical properties of UV-cured coatings were investigated such as gel content, solvent resistance, hardness, flexibility and tensile tests. The thermal behavior of coatings was also evaluated. It was observed that the tensile properties and thermal stabilities of boron modified epoxy coatings mainly depend on the boron content.     

丙烯酸酯/环氧的自由基/阳离子同步光聚合混合体系的研究

科学技术的进步,对新材料的要求逐步向着多功能和高性能的方向发展,单组分材料已难于满足这种要求,在高分子材料方面,人们采用了共混、接枝、嵌段等方法以达到改善和提高性能的目的。感光性高分子是一类很重要的功能材料,至今,大部分采用自由基聚合方式制备。近年来,阳离子引发体系发展很快,特别鎓盐光引发体系受到很大的重视,发展迅速。目前自由基聚合及阳离子聚合已经成为合成感光性高分子材料的二种最     

Flame retardancy and thermal property of novel UV-curable epoxy acrylate coatings modified by melamine-based hyperbranched polyphosphonate acrylate

A novel melamine-based hyperbranched polyphosphonate acrylate (MHPA), successfully synthesized via the Michael addition polymerization of 2-(2-amino-ethylamino)-4,6-bisethylamino-1,3,5-triazine with tri(acryloyloxyethyl) phosphate, was blended with the epoxy acrylate (EA) to prepare UV-cured flame retardant coatings. The study of their flammability revealed that MHPA can improve the flame retardancy and the sample with 45 wt% MHPA (EA3) showed a good intumescent behavior when combusted. The results of their thermal degradation displayed that MHPA had a dual effect on the thermal stability of EA: leading to its earlier degradation catalyzed by acidic species from the relatively weak phosphorus-bearing parts, but improving the thermal stability of the char layer at high temperature due to the formed intumescent phosphorus–carbon compounds. Besides, the total release amount of gas products of EA3 was much lower than that of pure EA and various flammable gases like hydrocarbons and highly toxic CO were also reduced     

Photoinduced insolubilization of SBS–acrylate films of high thickness under 405 nm

Photosensitive styrene–butadiene–styrene formulation was prepared for flexographic plate production. Real-time FTIR analyses of 500 μm thick samples were performed and polymerization reaction was followed from overtones of acrylate and SBR unsaturations. Photo bleaching studies of photoinitiator revealed that the optimum concentration is 1.6 p (0.98 wt%). In spite of the high viscosity of the resin, the termination mechanism in the SBS acrylate resin was found to be bimolecular. The oxygen inhibition was eliminated with the addition of triphenylphosphine (TPP), each TPP molecule consuming one oxygen molecule. It is shown that the curing of thick samples is homogeneous over the whole thickness of the samples. This is confirmed by dynamic mechanical analysis of the SBS–acrylate mixtures which revealed that a homogeneous network of acrylic and styrenic segments is much more significant as the illumination dose increases.     

Shape memory effect for recovering surface damages on polymer substrates

This paper describes the synthesis of novolac epoxy resin modified polyurethane acrylates (EPUAs) for generating a grafted polymer network, which is different from the conventional interpenetrating polymer networks (IPN). It starts with preparing epoxy acrylate resins (EA) by the ring-opening reaction of novolac epoxy resin (EP) and acrylic acid (AA). Epoxy acrylate copolymers (EPAcs) with hydroxyl groups were prepared by the copolymerization of EA and acrylic monomers. EPUAs were obtained by reacting EPAcs with curing agents (polyisocycanate HDI-trimer and phthalic anhydride). The chemical structures of the obtained EA and EPAcs were characterized by Fourier-transform infrared spectroscopy (FTIR) and ¹H nuclear magnetic resonance spectra (¹H NMR). The influence of EP on chemical and physical properties of EPUAs, including fracture surface morphology, thermal stability, tensile strength, elongation at break, glass transition temperature (T_g), cross-linking density, shore hardness, water absorption, adhesion, etc., were investigated as well. It is demonstrated that the incorporation of EP into EPUAs greatly enhances the above physico-chemical properties of EPUAs.     

Study of UV-curable coatings for optical fibers

Three kinds of UV-curable prepolymers, urethane acrylate (UA), polysilicone acrylate (SA), and epoxy acrylate (EA) were prepared. These prepolymers were mixed in different proportions to modify the properties of an optical fiber coating. The relationships of component-property and structure-property of the mixture coatings were studied. When the proportion was SA:UA:EA=5:4:3, it was used for a single coating, however, the proportion SA:UA:EA=6:5:2 was used for a primary buffer coating. These mixture coatings were applied to optical fibers. No. 30 Guan Shan Road, Wuhan 430074, P.R. China.     

Preparation and characterization of UV‐cured hybrid coatings by triethoxysilane‐modified dimethacrylate based on bisphenol‐s epoxy

Novel hybrid oligomers based on a UV‐curable bisphenol‐S epoxy dimethacrylate (DBSMA) were synthetized. DBSMA was modified with various amount of (3‐isocyanatopropyl)triethoxysilane coupling agent. The modification degree of the hybrid oligomer was varied from 0 to70 wt %. The photopolymerization kinetics was monitored by a real‐time infrared spectroscopy. The conversion and rate of hybrid coatings increased with the increase in modification degree. UV‐curable, hard, and transparent organic–inorganic hybrid coatings were prepared. They were performed by the analyses of various properties such as surface and mechanical properties. Results from the mechanical measurements showed that the properties of hybrid coatings improved with the increase in modification degree. The thermal behavior of coatings was also investigated. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Fabrication of an epoxy graft poly(St-acrylate) composite latex and its functional properties as a steel coating

A novel method for preparing epoxy graft poly(St-acrylate) composite latex with high graft ratio has been devised. First, esterification was carried out between acrylic acid and an epoxy resin using the monomer as the solvent. The obtained sample, still in solution in the monomer, was emulsified to miniemulsion droplets together with other monomers. Finally, the epoxy graft acrylate composite latex was prepared by miniemulsion copolymerization. This technology will eliminate pollution arising from the organic solvent when solvent-borne systems are used. The enhanced graft ratio was confirmed by FTIR and ¹H NMR measurements. The results indicated that the acrylic monomer was grafted onto the epoxy chain. TEM showed the graft composite latex to have a spherical structure with diameter 100 nm. The adhesive performance and anti-corrosive properties on a steel substrate, as measured by salt-spray resistance, were maximized when 4.0% acrylic acid was added to the epoxy resin. Dynamic mechanical analysis (DMA) has been employed to test the damping properties of the composite latex coatings. It was interesting that the tan δ peak values of the coatings were as high as 2.15, clearly exceeding those of general damping materials. Our findings suggest great potential for the composite latex in the field of functional steel coatings.     

Synthesis and characterization of flame retarding UV‐curable organic–inorganic hybrid coatings

UV‐curable, organic–inorganic hybrid materials were synthesized via sol–gel reactions for tetraethylorthosilicate, and methacryloxypropyl trimethoxysilane in the presence of the acrylated phenylphosphine oxide resin (APPO) and a bisphenol‐A‐based epoxy acrylate resin. The sol–gel precursor content in the hybrid coatings was varied from 0 to 30 wt %. The adhesion, flexibility, and hardness of the coatings were characterized. The influences of the amounts of inorganic component incorporated into the coatings were studied. Results from the mechanical measurements show that the properties of hybrid coatings improve with the increase in sol–gel precursor content. In addition, thermal properties of the hybrids were studied by thermogravimetric analysis in air atmosphere. The char yield of pure organic coating was 32% and that of 30 wt % silicate containing hybrid coating was 30% at 500°C in air atmosphere. This result demonstrates the pronounced effect of APPO on the flame retardance of coatings. Gas chromatography/mass spectrometry analyses showed that the initial weight loss obtained in thermogravimetric analysis is due to the degradation products of the photoinitator and the reactive diluent. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1906–1914, 2006     

Factors influencing the stability and film properties of acrylic/alkyd water-reducible hybrid systems using a response surface technique

Acrylic-grafted-alkyd resins were prepared by free radical chemistry. Long, medium, and short oil alkyds were prepared using soybean oil, glycerol, phthalic anhydride (PA), and tetrahydrophthalic anhydride (THPA) and used as the alkyd phase. Acrylic co-monomer formulas containing methyl methacrylate (MMA), butyl acrylate (BA), methacrylic acid (MAA), and vinyl trimethoxysilane (VTMS) were polymerized in the presence of the different alkyds using 2,2′-azobisisobutyronitrile (AIBN) as the initiator to obtain the final grafted structures. Design of experiments was used to understand how different variables in the synthesis of the acrylated-alkyds affect the film performance. A Box–Behnkin design was used, varying the oil length of the alkyd phase, the degree of unsaturation in the polyester backbone, and acrylic to alkyd ratio. Acrylic–alkyd hybrid resins were reduced with an amine/water mixture. The hydrolytic stability of hybrid alkyd dispersed in water was evaluated. Cured films were prepared and basic coatings properties were also evaluated. It was found that the oil length of the alkyd is the most dominant factor for final coatings properties of the resins. The hydrolytic stability was dependent on the acrylic to alkyd ratio. The oil length of the alkyd backbone had a minimal effect on stability of the resin and film performance.     

Scratch resistance of nano-silica reinforced acrylic coatings

Organic–inorganic hybrid coatings were obtained by a dual-curing process combining the sol–gel reaction with the UV-induced polymerization technique by starting from bisphenol A ethoxylate (15 EO/phenol) dimethacrylate (BEMA, as organic network former), methacryloyloxypropyl-trimethoxysilane (MEMO, as coupling agent) and tetraethoxysilane (TEOS, as inorganic silica network precursor). For comparison, TEOS was also substituted with preformed silica nanoparticles. Scratch test was carried out in order to study the scratch resistance of that silica reinforced acrylic resins. Excellent scratch resistant coatings were obtained by UV and sol–gel dual curing process. On the contrary, coatings with very poor scratch resistance were obtained by dispersing preformed nano-silica into the acrylic resin indicating the key role played by the morphology of the inorganic filler and its interaction with the organic matrix.     

环氧树脂/环氧丙烯酸酯混杂光固化材料的结构与性能

以预聚物双酚A环氧树脂（E-44）和双酚A环氧丙烯酸酯（EA）为主要原料加入一定的单体和引发剂配制成混杂光固化树脂。运用FTIR、DMA、TG及TEM等手段,表征了混杂光固化材料的结构,讨论了环氧树脂含量对材料固化程度和结构变化的影响。结果表明,混杂光固化材料具有2个玻璃化转变温度,具有良好的阻尼性能及热温度性能。     

Preparation and characterization of weather resistant silicone/acrylic resin coatings

Preparation and characterization of weather resistant silicone/acrylic resin coatings were conducted. In order to prepare these coatings, a silicone/acrylic resin (KLD) was first prepared by an addition polymerization reaction of monomers, including n-butyl acrylate, methyl methacrylate, n-butyl methacrylate, and 3-methacryloxypropyltrimethoxysilane (MPTS). In the preparation of the silicone/acrylic resin, T_g of the acrylic copolymer was fixed at 40°C and the contents of MPTS were varied to be 10, 20, and 30 wt%. The weather resistant silicone/acrylic resin coatings were then prepared by blending the synthesized silicone/acrylic resin and TiO₂. The viscosity of the synthesized resin decreased with the content of MPTS, whereas the thermal stability at high temperature increased. The prepared coatings exhibited excellent adhesion to various substrates, and various physical properties of the coatings were satisfactory. The weatherability of the coatings was tested three ways: outdoor exposure test, Weather-Ometer (WOM), and QUV accelerated weatherability tester (QUV). The gloss retention, yellowness index difference, color difference, and lightness index difference were improved at high MPTS concentration. The coatings containing 30 wt% MPTS have especially good weather properties. Dept. of Chem. Eng., Yongin 449-728, Korea. Ansan 425-110, Korea.     

Multifunctional NIR-reflective and self-cleaning UV-cured coating for solar cell applications based on cycloaliphatic epoxy resin

We report here a simple, cheap and scale up process for obtaining a multifunctional coating with both, IR reflective and hydrophobic properties. These coatings can be applied on solar devices in order to limit their overheating under operating conditions. The system is based on UV-curable epoxy coating containing IR-reflective fillers and a silicone additive to modify the surface properties with a good hydrophobicity enhancement. The filler dispersion into the epoxy UV-curable resin did not significantly influence the photocuring rate, while a slight decrease of the final epoxy group conversion was evidenced. The optical properties of the obtained coatings have been evaluated by UV–vis–NIR spectroscopy showing that the films act as good “filters” in the NIR region, giving rise to a reduction of the absorbed heat and of the working temperature of the cells. A pronounced increase of hydrophobicity for the films containing the silicone additive was observed. The optical properties were not affected by the addition of the silicone additive.