Water resistance of the membranes for UV curable waterborne polyurethane dispersions

The water absorption of the membranes made from UV curable waterborne polyurethane dispersions (UV-PUDs) was investigated systematically and correlated with the nature of the polymer and its gel content after curing. It was found that the water absorption of the membranes was reduced significantly by using polyester polyols, reducing the COOH content and increasing the gel content through a higher CC level. In particular, the membranes made from polyurethanes having hydroxyl-terminated polybutadiene (HTPB) or modified with dihydroxybutyl-terminated polydimethylsiloxane (PDMS) presented a superior water resistance. The results showed a linear relationship between the water absorption and the surface tension of the membrane.     

梳型UV固化水性聚氨酯树脂的制备与表征

通过引入含双键基团的中间体制备了分子链侧基、端基均含可UV固化基团的梳型水性聚氨酯树脂。采1用红外光谱仪FTIR、核磁共振仪H NMR、热重分析仪TGA等分析手段对样品的结构与性能进行了表征。分析表明,所得产品符合预期分子结构的设计,为半透明泛蓝光乳液,粒径细微均匀;固化层呈现2个快速失重温度区间。中间体的加入增强了固化层的耐溶剂性和硬度,附着力、拉伸强度和交联密度也得到提高。()()()     

Effect of the hard segment on the properties of UV curable waterborne blocked polyurethanes

Two types of UV curable waterborne blocked polyurethanes (PUs) were obtained from 2,4-tolylene diisocyanate(TDI) and isophorone diisocyanate (IPDI), which had the same soft segments and different hard segments. The PUs contained both the UV curable C=C bond and the blocked NCO groups which could be de-blocked when heated. Effect of the hard segment on the properties of the two types of PUs was investigated. The FTIR spectra method was employed to confirm the structure of the PUs. The photo-DSC was used to study the photo-polymerization rate of the PUs under UV irradiation in the presence of a photo-initiator and the C=C conversion behaviors. Heating-up IR analysis was used to track the de-blocking process and the heat curing process. The thermal degradation analysis (TGA) was employed to investigate the thermal stability of the UV cured films before and after heat curing process. Dynamic mechanical properties of the UV and heat cured films were investigated by the dynamic mechanical thermal analysis (DMTA).     

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.     

Effect of average functionality on properties of UV-curable waterborne polyurethane-acrylate

A series of ultraviolet (UV) curable waterborne polyurethane-acrylate (WPUA) with different average functionalities were synthesized in new methods. The chemical structures of WPUA were confirmed by Fourier-transform infrared spectroscopy (FT-IR) and the effect of average functionality on properties of WPUA was systemically investigated. It was found that the average functionality had a positive effect on the water resistance and tensile strength of WPUA, to make optimal formation of WPUA molecule chains available, whereas the increasing of average functionality decreased the viscosity and extension of WPUA samples. Besides, through the investigation on the UV curing kinetics, it was found that the average functionality too high or too low was unfavorable for the increase of unsaturation conversion. The morphology and microstructure of WPUA films were also comprehensively discussed with WAXD patterns and fractured surface observed from SEM images.     

Synthesis and properties of waterborne UV‐curable polydimethylsiloxane‐based polyurethane oligomers: UV‐cured film with excellent water resistance and thermostability

Abstract

This paper designed and synthesized a series of waterborne UV-curable polydimethylsiloxane‐based polyurethane oligomers which contain polydimethylsiloxane segment in the end of the main chain, a plurality of double bonds in the side chain and two kinds of hydrophilic groups including nonionic polyethylene glycol with low molecular weight and ionic quaternary ammonium salt groups. The unique structure endowed not only the oligomer with an excellent water solubility, but also the UV-cured film with hydrophobicity, thermostability and mechanical properties. The prepared oligomers could form a stable white emulsion and had excellent photopolymerization capability, and their conversions of double bonds were all over 92%. The UV-cured film containing long chain polydimethylsiloxane exhibited better hydrophobicity, heat resistance and tensile strength. The polydimethylsiloxane segment located in the end of the oligomer molecular chain was more conducive to its enrichment in the surface of the cured films and improving of the hydrophobicity of the cured films. The water absorption, surface water contact angle and the initial decomposition temperature (T_5%) of the obtained UV-cured films were 2.7%, 91 and 301?°C, respectively.     

The utilization of carbon nitride to reinforce the mechanical and thermal properties of UV-curable waterborne polyurethane acrylate coatings

The waterborne polyurethane-acrylate (WPUA and Wsi-PUA) oligomers were prepared by anionic self-emulsifying method, using isophorone diisocyanate (IPDI), polyethylene glycol (PEG), dimethylol propionic acid (DMPA), vinyl hydroxyl silicone oil (VHSO) and hydroxyethyl methyl acrylate (HEMA) as raw materials. Then, a series of UV-curable waterborne Wsi-PUA–C₃N₄ composites containing different content of g-C₃N₄ were obtained with oligomer and photoinitiator Darocur 1173. FTIR, XRD, TEM, SEM, and TGA were employed to investigate the structure, morphology and thermal property of the Wsi-PUA–C₃N₄ composite films. The effect of g-C₃N₄ content on the performance was also investigated. The mechanical performance, water resistance and gel content of UV-PUA films were measured. It was found that with g-C₃N₄ particle was introduced into Wsi-PUA oligomer, the hardness, tensile strength, gel content, water resistance and thermal stability of composite films were significantly augmented. Moreover, when the content of g-C₃N₄ was 1.0 wt.%, the UV-curable film had the best mechanical property. The obtained composite is promising for a number of applications, e.g., for protecting the surfaces of metal and wood.     

水性光固化改性氯化聚丙烯的制备及性能

以丙烯酸(AA)和甲基丙烯酸羟乙酯(HEMA)对氯化聚丙烯(CPP)进行溶液接枝改性。考察了AA与HEMA两种单体总用量(AA与HEMA两种单体质量之和占CPP质量的百分数,下同)及引发剂用量(即引发剂质量占CPP及单体总质量的百分数,下同)对接枝率的影响,得到了最佳AA与HEMA总用量为20%,最佳引发剂用量为3%,在该条件下接枝率达到8.81%。然后以甲基丙烯酰氯对接枝改性CPP进行光固活性成分改性,研究了不同AA用量的水性光固化改性CPP乳液性能、表面张力及附着力。结果表明,AA用量占AA和HEMA总质量20%~50%,均能形成乳液,乳液粒径随AA用量增多而减小;水性化改性产物经光固活性成分改性后,以及经光固活性成分改性后的产物光固化前后,表面性能良好,表面张力均在40 m N/m以上,附着力得到提高。该材料符合环保要求,具有良好的应用前景。     

光/湿双固化聚氨酯热熔胶的制备与性能研究

以多元醇、异氰酸酯、含羟基丙烯酸酯和光引发剂等为原料,制备了PET(聚酯)基材粘接用光/湿双固化PU(聚氨酯)-PUA(聚氨酯丙烯酸酯)型反应性HMA(热熔胶)。研究结果表明:该HMA中同时含有可光固化基团(C=C)和可湿固化基团(-NCO);当n(C=C)∶n(-NCO)=20∶80、w(复合光引发剂)=1.5%~2.0%和引入甲基丙烯酸羟乙酯(HEMA)时,相应HMA具有较高的初始强度和最终强度;光/湿双固化HMA的透明度高于湿固化HMA,说明UV固化是增加光/湿双固化HMA透明度的主要原因。     

水性聚氨酯胶膜的耐水性能研究

采用预聚体法,以聚酯多元醇、甲苯二异氰酸酯、二羟甲基丙酸(DMPA)制备了聚酯型水性聚氨酯乳液,考察了亲水扩链剂DMPA用量、NCO/OH值、中和剂的种类、中和度、扩链剂乙二胺用量对乳液涂膜耐水性的影响,制备了耐水性较好的水性聚氨酯乳液。     

双环戊二烯甲基丙烯酸酯的合成及其紫外光固化性能研究

以双环戊二烯与甲基丙烯酸为原料,在三氟化硼乙醚络合物催化剂的作用下,合成了双环戊二烯甲基丙烯酸酯（DCPMA）,并用~1HNMR、FT-IR对产品进行了表征分析。结果表明：当n（甲基丙烯酸）：n（双环戊二烯）=1.2：1、催化剂三氟化硼乙醚的加入量为0.6%、阻聚剂对苯二酚加入量为0.4%时,产品收率达52.5%。将DCPMA用于紫外光固化涂料中,与丙烯酸羟乙酯、甲基丙烯酸羟乙酯、2-苯氧基乙基丙烯酸酯、丙烯酸异冰片酯等4种单官能度的单体相比,涂料的固化收缩率低、固化膜的耐磨性好、附着力强、热稳定性高。     

紫外固化粉末涂料的合成及固化研究

用E-12、E-20环氧树脂与丙烯酸反应,合成了可紫外光固化的环氧丙烯酸酯预聚物,并对产物进行固化研究。讨论了催化剂的种类、反应温度、反应时间等对合成产物的影响,光引发剂的种类、光照时间等对固化产物的影响。结果表明:环氧树脂与丙烯酸以甲苯为溶剂、四丁基溴化铵为催化剂,在110℃下反应180 min为较适宜的反应条件;环氧丙烯酸酯以TPO为引发剂,120 w/cm的紫外灯光照15 s为较宜适的固化条件。     

Facile synthesis of waterborne UV-curable polyurethane/silica nanocomposites and morphology,physical properties of its nanostructured films

Waterborne UV-curable polyurethane (WUPU)/silica nanocomposites were prepared by in situ method using aqueous silica sol. SEM examinations of hybrid films indicated that the nanosilica were well dispersed in the matrix. Atomic force microscopy revealed that the microphase separation between polyurethane and silica was significantly affected by the amount of silica incorporated. DMA analysis showed that the nanocomposite films with silica nanoparticles showed a single tan δ peak, which implies that soft and hard segments of polyurethane are well phase mixed. The nanostructure films displayed enhanced storage modulus, tensile strength without sacrificing high elongation at break. The resulting transparent hybrid films are promising for a number of applications, e.g. for high performance water-based UV-curable coatings.     

聚氨酯丙烯酸酯软段结构对UV胶性能的影响

以几种不同结构的多元醇、异佛尔酮二异氰酸酯(IPDI)和丙烯酸羟乙酯为原料,合成了多种聚氨酯丙烯酸酯预聚物(PUA).按照同样比例的单体、引发剂及其他助剂配制成光固化胶粘剂(UV胶),考察了聚氨酯中多元醇结构对UV胶固化速度、黏结强度、胶膜性能等的影响.结果表明,聚氨酯结构中软段结构对UV胶粘剂性能影响比较大,合理地选...     

Highly branched polyurethane acrylates and their waterborne UV curing coating

A series of UV curable highly branched waterborne polyurethane acrylates (BWPUAs) were synthesized using an “oligomeric A₂ + B₃” approach. The thiol-endcapped difunctional oligomeric A₂ was synthesized first by the addition reaction of isophorone diisocyanate, α,α-dimethylol propionic acid and 2-hydroxyethyl acrylate, then further underwent thiol-Michael reaction with 1,6-hexamethylene bis(thioglycolic acetate). Trimethylolpropane triacrylate was used as a B₃ monomer. The molecular structures were characterized with FT-IR and ¹H NMR spectroscopy. 1,6-Hexanediol diacrylate (HDDA) was incorporated into the polymeric chain for preparing the HDDA-modified BWPUAs (BWPUA-Hs). For the comparison, the linear waterborne polyurethane acrylate (LWPUA) was synthesized. The UV curing kinetics study results by using the photo-DSC approach showed that the BWPUAs possessed higher photopolymerization rate and final unsaturation conversion in the UV cured films compared with the LWPUA, which increased with the increase of unsaturation concentration in BWPUA. Moreover, the photopolymerization performance, and water and solvent resistance properties were greatly enhanced by the incorporation of HDDA segment into the BWPUA chain. The dynamic mechanical thermal analysis results showed that the elastic modulus in the rubbery plateau, and the glass transition temperature of UV cured film increased with increasing unsaturation concentration in BWPUA, whereas decreased with the introduction of HDDA flexible segment. The thermogravimetric analysis confirmed the high thermal stability of UV cured BWPUA films. All UV cured BWPUA and BWPUA-H films showed better flexibility and middle refractive indices due to the thioether linkage in the polymer network.     

紫外光固化胶粘剂的粘接强度研究

以二官能团PUA(聚氨酯丙烯酸酯)为基体树脂、四氢呋喃丙烯酸酯为稀释单体、γ-缩水甘油醚基丙基三甲氧基硅烷(KH-560)为偶联剂、HCPK(1-羟基环己基苯基甲酮)为光引发剂和nano-SiO2(纳米二氧化硅)为填料,成功制备出一种UV(紫外光)固化胶。将UV固化胶用于PC(聚碳酸酯)塑料片材的胶接,并以该胶接件的T型剥离强度作为考核指标,采用单因素试验法优选出制备UV固化胶的较佳配方。结果表明:当w(二官能团PUA)=64%、w(HCPK)=3.0%、w(KH-560)=1.00%、w(四氢呋喃丙烯酸酯)=30%和w(nano-SiO2)=2.0%时,UV固化胶的剥离强度达到甚至超过市售同类产品(loctite3106)。     

一种高性能紫外光固化胶粘剂的制备

以异佛尔酮二异氰酸酯IPDI、改性聚醚多元醇、甲基丙烯酸羟乙酯(HEMA)为主要原料,制备了聚氨酯丙烯酸酯PU1。考查了水解剥离型紫外光固化胶粘剂的基本配方中各主要组分对粘接强度和水解剥离性能的影响。研究结果表明,PU1作为基础树脂玻璃粘接强度高同时剥离时间短分别为12.2 MPa和30 min;亲水性单体聚乙二醇二丙烯酸酯比单官能甲氧基聚乙二醇丙烯酸酯在粘接强度和水解剥离速度上优异。其中FA-260A均衡性最佳,玻璃粘接强度12.5 MPa,水解剥离时间20 min;高折射率、疏水性环状单体对基本配方的折射率的调节有帮助,可以实现胶粘剂折射率1.50的要求,其中低官能度邻苯基苯氧乙基丙烯酸酯性能最佳;溶剂选用环保型低级醇对水解剥离性能有帮助。()()     

A simple Raman technique to measure the degree of cure in UV curable coatings

The curing behavior of four UV curable clearcoats was examined using spectra from a confocal Raman microscope. The disappearance of the C=C line near 1636 cm⁻¹ provides the signature for the curing of the samples, but quantification of the degree of cure by standard peak-fitting and baseline subtraction methods does not work well because of sample fluorescence, baseline shifts and overlapping peaks. A smoothed second-derivative processing approach overcomes all of these difficulties and provides a simple, fast and objective quantification procedure. Steep cure gradients through the thickness of the clearcoat, due to screening of the bottom of the clearcoat by both the UVA and photoinitiator, were observed. Cure gradients at the top of the clearcoat due to oxygen inhibition were also observed. The most complete cure throughout the film thickness was obtained with a mixture of standard and red-shifted photoinitiators.     

紫外光固化涂料附着力促进剂的研制

为了解决紫外光固化涂料附着力差的问题,以丙烯酸羟乙酯或甲基丙烯酸羟乙酯与五氧化二磷为原料在一定条件下进行亲电加成反应制得可紫外光固化的含磷酸基团的附着力促进剂。采用酸值跟踪测试确定总反应时间为3.5h。对产品进行红外光谱分析,表明反应物中的羟基已经完全反应以及产物中磷酸基团与CC双键的形成。对比了自制产品与市售产品在不同板材上的性能,结果表明这两种产品对紫外光固化涂料与金属、玻璃、木材等极性基材都具有很好的附着促进作用,并确定了自制产品的优势。     

紫外光固化丙烯酸酯胶粘剂的研制

用甲基丙烯酸甲酯、丙烯酸丁酯、丙烯酸-β羟丙酯等单体共聚成光敏树脂（预聚物），加入适量甲基丙烯酸丙酯和光敏剂即得紫外光固化胶粘剂。当加入适量多官能丙烯酸酯（如季戊四醇三丙烯酸酯）时，可大大缩短胶的光固化时间。该胶对诸多基材粘接良好。