Physical and thermal properties of UV curable waterborne polyurethane dispersions incorporating hyperbranched aliphatic polyester of varying generation number

Three series of novel waterborne hyperbranched polyurethane acrylates for UV curable aqueous dispersions (WHPUD) based on hydroxy-functionalized hyperbranched aliphatic polyesters Boltorn™ of varying generation number were investigated. The effects of the overall composition, including acidic and acrylate groups, and functionality of hyperbranched polyester were studied in terms of particle size, rheology, photopolymerization kinetics, dynamic mechanical thermal as well as thermal degradation behaviors of WHPUDs. The average particle sizes of aqueous dispersions, 43-134 nm, were determined by laser light scattering. The stability and particle size were dependent on the amount of carboxylic acid groups, degree of neutralization, and molecular structure. The rheological features have revealed that all dispersions belong to pseudoplastic fluids. The shear thinning behavior of WHPUDs is more pronounced for lower generation of hyperbranched polyester. The photopolymerization rates of the resins under UV irradiation in the presence of a photoinitiator showed an increasing trend with higher functionality of acrylate. The glass transition temperature (T_g) of UV cured films evaluated by dynamic mechanical thermal analysis (DMTA) showed that the influence of end capping by hard segment consisting of IPDI-HEA is remarkable due to the increase of crosslink density. The T_g, storage modulus and loss modulus increased with increasing generation number from the second to the fourth. The results of TGA for cured WHPUD films indicated good thermal stability with no appreciable weight loss until 200 °C, and that an increase in the hard segment content provoked the increases in thermal degradation temperature. This behavior is rationalized by relating crosslink density dependence of chain end concentration and the generation number of hyperbranched polyester.     

光固化超支化聚氨酯丙烯酸酯的合成及其固化膜性能

以新戊二醇为核,二羟甲基丙酸为支化单体合成得到每个分子中含有16个端羟基的超支化脂肪族聚酯,将其与自制甲苯-2,4-二异氰酸酯.丙烯酸羟丙醅单体的NCO端基团反应,获得新型可紫外光固化的超支化聚氨酯丙烯酸醑.应用红外光谱分别对超支化聚酯、超支化聚氨酯丙烯酸酯及其紫外光固化胶膜的化学结构进行分析,同时应用力学性能测试、差示扫描量热分析、热重分析等手段对单体官能度及用量对固化膜物理性能和热性能的影响进行研究.结果表明:随着活性单体用量的增加,固化膜的抗冲击强度增加,硬度减小,活性单体官能度的增加有利于提高其硬度;热重分析结果表明固化膜具有两个热分解温度,初始分解温度大于200℃,另一分解温度约为375℃;差示扫描量热分析结果显示,固化膜具有两个玻璃化转变温度(Tg.s,Tg.h),随着活性单体官能度的增加,Tg.s降低,Tg.h升高,有利于相分离,而其用量的增加却不利于相分离;利用红外和凝胶法分析对比研究超支化聚氨酯丙烯酸酯的光固化行为,结果表明其不饱和双键的最终转化率高达90%.     

松香基UV固化超支化聚酯丙烯酸酯的合成

采用季戊四醇作为聚酯内核与二羟甲基丙酸(DMPA)发生酯化反应后,再与以松香为原料合成的马来海松酸酐(MPA)反应合成富含末端基团的超支化聚酯大分子(HBP),再分别将2-羟乙基丙烯酸酯(2-HEA)和五缩六乙二醇丙烯酸单酯(PEA-6)引入到HBP结构中,得到新型UV固化超支化树脂(HBR)。采用红外光谱对产物结构进行了表征,对固化膜进行了热重分析,通过动态力学谱测试了其粘弹性,并对涂膜的其他基本性能进行了测定。结果表明,所得树脂大都具有较低的粘度,漆膜硬度较好,对金属、塑料底材附着力较好。随着PEA-6用量的增加,产物的硬度和热力学稳定性能下降,柔韧性增加。     

Preparation and properties of poly(urethane acrylate) films for ultraviolet‐curable coatings

Four different UV‐curable poly(urethane acrylate)s were prepared through the reaction of two diisocyanates [i.e., toluene‐2,4‐diisocyanate (TDI) and isophorone diisocyanate (IPDI)] and two polyols [i.e., polycaprolactone triol (PCLT) and polycaprolactone diol (PCLD)], and they were characterized with Fourier transform infrared spectroscopy. The mechanical properties, thermal properties, and water sorption of the cured poly(urethane acrylate)s were also investigated with respect to the chemical structures of the polyols and diisocyanates. In comparison with linear PCLD–TDI and PCLD–IPDI, crosslinked PCLT–TDI and PCLT–IPDI with trifunctional PCLT showed relatively high thermal decomposition temperatures. The hardness and modulus of the UV‐cured poly(urethane acrylate) films, which were measured by a nanoindentation technique, were in the following increasing order: PCLD–IPDI ～ PCLD–TDI < PCLT–IPDI ～ PCLT–TDI. The pencil hardness was 3H for PCLT–IPDI and PCLT–TDI and HB for PCLD–IPDI and PCLD–TDI. Two urethane acrylates prepared from the trifunctional polyol showed better acid and alkali resistances than those made from the bifunctional polyol. These mechanical properties and chemical resistances may have been strongly dependent on the chain flexibility of the molecules and crosslinking density. Regardless of the functionality in the polyol, the change in the yellowness index showed a lower value in the poly(urethane acrylate) coating containing the aliphatic diisocyanate IPDI in comparison with the corresponding poly(urethane acrylate) with the aromatic diisocyanate TDI. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

氨基甲酸酯基丙烯酸酯的合成及其光固化性能

利用碳酸亚乙酯与1,6-己二胺、异佛尔酮二胺反应，制备出两种含氨基甲酸酯基的二元醇，基于氨基甲酸酯二元醇与1,6-己二醇二丙烯酸酯（HDDA）、新戊二醇二丙烯酸酯（NPGDA）及三羟甲基丙烷三丙烯酸酯（TMPTA）本体条件下的Oxa-Michael加成反应及酯交换反应，合成出6种含氨基甲酸酯基的丙烯酸酯混合物。利用FTIR及高分辨质谱分析了产物结构，用FTIR考察了所合成氨基甲酸酯基丙烯酸酯光固化过程的动力学,测定了光固化膜的性能。结果表明，在含占总质量分数3% 的2-羟基-2-甲基-1-苯基-1-丙酮（1173）光引发剂的引发下，氨基甲酸酯基丙烯酸酯能在30s内固化形成表面平整、柔韧性（0.5~2.5mm）良好、透明或半透明的膜；固化膜的凝胶率及铅笔硬度分别为92%~96%、4~5H，对玻璃的附着力为0~1级。     

Tetrafunctional acrylates based on β-hydroxy alkyl amides as crosslinkers for UV curable coatings

Ultraviolet (UV) curable coating formulations were prepared from novel crosslinking acrylates synthesized from β-hydroxy alkyl amides. Variations were done with respect to the nature of the monomer backbone by introducing aliphatic, aromatic and cycloaliphatic structures in between the amide groups. The synthesized multifunctional alcohols and acrylates were subjected to IR and NMR analysis for structure confirmation. The acrylates were dissolved in chloroform and the UV–vis spectrum was recorded to substantiate the presence of carbonyl group conjugated to the vinyl group. The new acrylates were added to basic formulation and exposed to UV radiation to get transparent films. The dynamic mechanical properties of the films cast from the formulations were assessed and studies on the effect of the synthesized crosslinking acrylate content and their nature on the viscoelastic properties of the films were carried out. Improvements in glass transition temperature (T_g) were observed with increasing percentage of crosslinker. Acrylates based on aromatic acid amides showed higher T_g than aliphatic acid amides. The storage modulus (E′) increased up to 10% and further increases in the crosslinker percentage led to a decrease in the modulus. The rubbery modulus depended on percentage of crosslinker and not on crosslinker structure.     

超支化聚氨酯丙烯酸酯的合成及其固化膜性能

以合成的甲苯-2,4-二异氰酸酯.丙烯酸羟丙酯(TDI.HPA)单体对超支化聚酯(HBPE)进行端羟基改性,得到超支化聚氨酯丙烯酸酯(HBPUA)。研究了反应温度、时间对产物游离—NCO含量的影响,通过摆杆硬度、附着力、柔韧性、冲击强度等测试研究了活性单体的种类及用量对固化膜性能的影响,并采用FT-IR及TG对HBPE,HBPUA及其固化膜进行了表征和分析。结果表明,合成HBPUA的最佳条件为:n(2,4-TDI):n(HPA):n(HBPE)=6:6:1,反应温度70℃,反应时间3 h,催化剂二月桂酸丁基锡(DBTDL)用量为总质量的0.6%;TDI.HPA的合成反应温度35℃,反应时间2.5 h,DBTDL用量为总质量的0.4%。采用己二醇二丙烯酸酯为活性单体并控制其质量分数为20%时,超支化聚氨酯丙烯酸酯涂膜的力学性能、热稳定性较好。     

Novel concept for low temperature curing powder coatings based on hyperbranched polyesters

The concept of using hyperbranched polymers as scaffolds for solid thermoset resin applications is de-scribed. A series of semi-crystalline methacrylate-functional aliphatic poly-esters has been synthesized and characterized for applications as solid thermoset resing, e.g., powder coating resins. The polyester resins have been crosslinked by UV irradiation producing either amorphous or semi-crystalline crosslinked films depending on the initial structure. The resins are based on hyperbranched aliphatic polyesters onto which crystalline linear aliphatic polyester chains have been grafted and end-capped with methacrylate moieties. The resins exhibit a rheological behavior suitable for low temperature curing powder coatings, i.e., films that can be readily formed and UV cured at temperatures below 80°C. Dept. of Polymer Technology, SE-100 44 Stockholm, Sweden. E-mails: matskg@polymer.kth.se. mave@polymer.kth.se, and andult@polymer.kth.se.     

Water‐soluble urethane acrylate ionomers: Effect of molecular structure on ultraviolet coating properties

Water‐soluble urethane acrylate ionomers containing dimethylolpropionic acid (DMPA) were synthesized, changing the molecular components, and their ultraviolet (UV) coating properties were studied. It was found that the UV coating properties of the urethane acrylate ionomer films were very dependent on the molecular weight of the soft segment, the type of the diisocyanate, and the amount of neutralization. In general observations, the cured films displayed much improved mechanical properties, compared with conventional urethane acrylate film not containing ionic groups. The main reason for the improved film properties seemed to be attributed to the presence of ionic groups in the network. In dynamic mechanical analysis, two distinct glass transition temperatures, corresponding to the ionic hard domains and soft domains, were detected at high content of ionic groups. This suggested that the urethane acrylate network be composed of two phases. Consequently, the ionic hard domains formed by the phase separation from crosslinked network could act as a reinforcing filler, which possibly explains the improved film properties of the urethane acrylate ionomer films. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1853–1860, 2000     

Preparation of waterborne hyperbranched polyurethane acrylate/LDH nanocomposite

A series of novel waterborne hyperbranched polyurethane acrylate (WHPUA)/layered double hydroxide (LDH) nanocomposites based on hyperbranched aliphatic polyester Boltorn H20 (H20) and MgAl-LDH were successfully synthesized by in situ polymerization approach. The MgAl-LDH was firstly modified by sodium dodecyl sulfate (SDS) through the coprecipitation method, and then grafted by isophorone diisocyanate (IPDI), forming a complex with NCO groups at the surface and interlayer of LDH (LDH-DS-NCO). The residual hydroxyl groups after modification with succinic anhydride were crosslinked by the semi-adduct of IPDI reacted with HEA, and LDH-DS-NCO, followed by a neutralization reaction with triethylamine. The resulting water dispersible hyperbranched polyurethane acrylate WHPUA/LDH hybrid oligomer was then exposed to a medium pressure mercury lamp, forming a partially exfoliated WHPUA/LDH nanocomposite in the presence of a fragmental photoinitiator. The chemical structure, crystal configuration, morphology of WHPUA/LDH nanocomposite were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and high resolution transmission electron microscopy. The experimental results indicated that both the intercalated and exfoliated structures were formed in the UV cured polymer/LDH nanocomposite. The TGA results showed that the thermal stability was improved. Moreover, the pencil hardness was greatly increased, and the flexibility remained at an acceptable level for the UV cured polymer/LDH nanocomposites.     

光固化胶粘剂的开发应用

介绍了3种光固化树脂的制备工艺，研究了不同改性体系对光敏树脂性能的影响，不饱和聚酯树脂（UPR）具备低粘度，环氧丙烯酸酯树脂（AE）质硬，端羧基聚醚（CTPE）改性环氧丙烯酸酯（AEPE）有效的提高了材料的韧性，聚氨酯丙烯酸酯树脂可得到柔软直至强韧的固化物。     

Studies on synthesis and characterization of a novel acrylic aromatic amide oligomer of aminolysed endproducts generated from pet waste with hydrazine monohydrate and its photocuring with acrylate monomers

A novel acrylic aromatic amide oligomer was synthesized by using depolymerized end product of PET waste with hydrazine monohydrate. The end product of aminolysed PET waste was synthesized under ambient conditions and was used in the preparation of novel acrylic oligomer with the reaction of acryloyl chloride prepared from acrylic acid. The acrylic oligomer was characterized by spectroscopic techniques, such as FTIR, ¹H‐NMR, UV, Mass spectrometry, and by other analytical techniques such as, Iodine value, TGA, and DSC. The proposed structure of the oligomer is supported by its spectral analysis and the same is inferred from other techniques. The acrylic oligomer mixed with other acrylate monomers such as methylmethacrylate, ethylhexylacrylate, acrylic acid, and photoinitiator, can be cured by UV radiation and can thus be used as an adhesion promoter on metal/glass surface. This article presents the possibility of using a difunctional aromatic amide oligomer with excellent hydrogen bonding capacity as an alternative to urethane acrylates in radiation curable formulations. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation of UV-curable emulsions using PEG-modified urethane acrylates: The effect of nonionic and anionic groups

To prepare self-emulsificable urethane acrylate resin, PEG-modified urethane acrylates (PMUA), containing polyoxyethylene chains as a terminal hydrophilic group and urethane acrylate anionomers (UAA) incorporated dimethylolpropionic acid (DMPA) as a pendant hydrophilic one were synthesized. For PMUA emulsions, the reaction molar ratio of PEG to 2-hydroxyethyl methacrylate (2-HEMA) significantly influenced the viscosity and droplet size of the emulsion and tensile strength of cured films. These emulsions were stable to pH change and the addition of electrolyte, but coagulated around 60°C. In the case of UAA, emulsions, however, were very stable to elevated temperatures and coagulated in adding even a little bit of electrolyte. For soap-free emulsions of the mixture of PMUA and UAA, emulsion stabilities of these mixtures against temperature, pH change, the addition of electrolyte, and the rate of shear and freeze–thaw increased synergetically. Additionally, the tensile strength of cured films was also improved. © 1996 John Wiley & Sons, Inc.     

Photorheology of Fast UV‐Curing Multifunctional Acrylates

Summary: The fast photopolymerization of different multifunctional acrylates was analyzed by means of photorheology. The materials studied included a penta/hexaacrylate monomer and two different acrylated hyperbranched polymers. The sensitivity of the commercial rheometer was improved several‐fold, by a combination of an adaptive filter algorithm and improved data treatment, using powerful oversampling acquisition hardware. The novel set‐up was capable of monitoring up to a five orders of magnitude increase in shear modulus within short experiment timescales (about 10 s). The improvement in sensitivity and acquisition rate enabled the induction time, gelation, and vitrification of the multifunctional acrylates to be determined. In addition, the influence of UV intensity on stiffness build‐up within these materials was studied. In the case of the penta/hexaacrylate system, gelation and vitrification were detected as distinct events, in contrast to the second‐generation hyperbranched polyester, for which vitrification could not be identified. These findings are related to the difference in the glass transition temperature of the cured networks.

Absolute value of the complex shear modulus as a function of time for different acrylate monomers during UV curing.     

Fluorinated hyperbranched polyester acrylate used as an additive for UV curing coatings

The fluorinated hyperbranched polyester acrylate (FHPA) was synthesized by modifying the hyperbranched polyester Boltorn H20 with fluorinated isocyanate, and characterized with ¹H NMR and FTIR spectroscopic analysis. The water and oil wettability of the UV cured film with FHPA as an additive was investigated by measuring the contact angle. The results showed that an extremely low concentration of FHPA, even below 0.1 wt%, resulted in efficient decrement of the surface tension of UV cured film to 10–15 mN/m, and thus makes the film highly hydrophobic and oleophobic. The film with FHPA addition was stable in acidic and neutral solutions, and still had good water repellency after immersion in a pH 1 solution for several days. The X-ray photoelectron spectroscopic analysis confirmed that the film surface was enriched with fluorinated species. Moreover, the molecule with the highest average number of perfluoroalkyl groups had the highest tendency to aggregate at the surface of the UV cured film.     

Effects of reactive diluents on mechanical and physical properties of a UV curable acrylated urethane prepolymer

In this study, the dependence of the mechanical properties of a UV curable acrylated urethane on reactive diluent types and their amounts was investigated. The acrylated urethane prepolymer was synthesized from isophorone diisocyanate (IPDI), an aliphatic diisocyanate, and polypropylene glycol monomethacrylate (PPGMMA) by stepwise addition reaction. UV sensitive mixtures containing N-vinylpyrrolidinone (NVP), thiodiethylene glycol diacrylate (TDGDA) and isobornyl acrylate (IBoA) as reactive diluents were irradiated by UV light. An increase in reactive diluent content, either TDGDA or IBoA, caused an increase in tensile strength and a decrease in elongation values. In contrast, above a certain concentration a decrease in tensil strength was observed when NVP was used as reactive diluent. The water absorption capacities of the UV curable acrylated urethane films were observed to depend on type and amount of reactive diluent that was used. Thermooxidative properties of the films were also improved by incorporation of reactive diluents into formulations.     

Effect of acid groups in hydroxyl functional resins on the properties of polyester-urethane powder coatings

The concept of using hyperbranched polymers as scaffolds for solid thermoset resin applications is de-scribed. A series of semi-crystalline methacrylae-functional aliphaic poly-esters has been synthesized and characterized for applications as solid thermoset resins, e.g., powder coating resins. The polyester resin have been croslinked by UV irradiation producing either amorphous or semi-crystalline crosslinked films depending on the initial structure. The esins are based on hyperbranced aliphatic polyesters onto which crystaline linear aliphatic polyester chains have been grafted and end-capped with methacrylate moieties. The resins exhibit a rheological behavior suitable for low temperature curing powder coaings, i.e., films that can be readily formed and UV cured a temperatures below 80 °C. 2000 Lake Park Drive Smyrna GA 30080 E-Mails: bin.wu@ucb-group.com and sanilay.padaki@ucb-group.com     

Preparation of UV curable emulsions using PEG-modified urethane acrylates and their coating properties III: Effects of epoxy acrylate

Water-dispersible UV-curable urethane acrylate emulsions were prepared with polyethylene glycol (PEG)-modified urethane acrylates (PMUA), containing terminal hydrophilic polyoxyethylene chains. To improve physical properties of PMUA, epoxy acrylate (EA) having high thermal stability and hardness, was mixed with five kinds of PMUA containing different chain lengths of polyoxyethylene (POE). For PMUA/EA mixtures, the composition ratio of EA to PMUA and the chain length of POE greatly influenced the size of droplets of emulsions and the physical properties of their cured films. At higher EA to PMUA ratio, the physical properties decreased, which was due to phase separation between EA and PMUA. Phase separation was confirmed by scanning electron microscopy. Received: 13 September 1996/Revised: 27 November 1996/2 December 1996     

Preparation of hyperbranched polyester polyol-based urethane acrylates and applications on UV-curable wood coatings

In the present study, hyperbranched urethane acrylates (UA/HB-PEs) were synthesized by modifying the hydroxyl groups of hyperbranched polyester polyols (HB-PEs). The structure of oligomers were characterized by FTIR and ¹H NMR spectroscopic techniques. Formulations containing UA/HB-PEs, reactive diluents, and photoinitiator were applied onto wood substrates and successfully polymerized under UV-irradiation. The coating performances and thermal properties of UV-cured films were evaluated. The studies on film characteristics reveal that the incorporation of UA/HB-PE afforded coatings with good adhesion and high gloss properties. It is observed that UV-cured coatings originated from [2,2-bis(4-??-hydroxyethoxy) phenyl propane] (HB-HEPA)- and [2,2-bis(4-??-hydroxyethoxy) phenyl 6F propane] (HB-HEPFA)-based oligomers possessed better surface and mechanical properties.     

超支化聚酯的合成及改性环氧树脂的研究

以季戊四醇为核,2,2-二羟甲基丙酸为增长单体,对苯甲磺酸为催化剂,合成了超支化聚酯,通过FI-IR图谱对超支化聚酯进行结构表征,证明得到端基为羟基的超支化聚酯。采用超支化聚酯做增韧剂,研究其对环氧/四氢苯酐固化体系的增韧作用,探讨了超支化聚酯的分子量(代数)、超支化聚酯的含量、固化温度等因素对环氧树脂固化体系力学韧性的影响。