Star oligomers and hyperbranched polymers in low VOC polyurethane coatings: Part III

Conclusion  In this paper the effects of the functionality of hydroxyl functional star oligomers and dendritic polys have been demonstrated in a low VOC clear 2-component clear coat crosslinked with a polysocyanate. At a fixed initial composition of the overall system and with the same reactivity of hydroxyl and isocyanate functional groups, the molecular weight increase as a function of time and the conversion can be calculated using the theory of branching processes. The study has shown that the practical results agree quite well with theory and that the potlife is shortened in case of higher functionality as well as in the case of a broad functionality distribution. The hardness in such a system is not only the effect of functionality, but also of solvent evaporation during crosslinking. If the molecular weight increase upon drying is too fast due to a high functionality (and/or distribution), early gel formation can result in a low film glass transition temperature and hardness due to solvent entrapment.     

Star oligomers for low VOC polyurethane coatings

Conclusion  Hydroxyl functional star oligomers prepared by ring-opening polycondensation have a narrow molecular weight and composition distribution. Such oligomers give a solids/viscosity advantage over linear structures at the same molecular weight and can be used in low VOC two component polyurethane coatings. The solids/viscosity advantage is a combination of the highly branched structure and the narrow molecular weight distribution. Acrylic polyols formulated at the same molecular weight/polarity/average functionality and hydroxyl value give poorer drying properties. This difference can be explained by the fact that the free radical polymerisation technique leads to polymer compositions having a broad molecular weight and functionality distribution and high fractions of polymer with a low functionality. The potlife of acrylic polyols based formulations is adversely affected by the higher fractions of high molecular weight material and with a high average functionality. In low VOC polyurethane formulations star oligomers need to be formulated within a narrow range of compositions (TG, polarity), functionality and molecular weight to get an optimum balance of drying properties and potlife.     

Design and Preparation of Tertiary Amine Modified Polyurethane Acrylate Oligomer with Co‐Initiation/Polymerization Bifunctions for Photo‐Curable Inkjet Printing of Textiles

In order to resolve the conflict issues existing in currently available polyurethane acrylate (PUA) oligomers for photo‐curable inkjet printing of textile, and to avoid the safety problems caused by the immigration of small molecule amine co‐initiator, a series of tertiary amine modified PUA oligomers are delicately designed and synthesized. The chemical structures of the synthesized PUA oligomers are confirmed by FTIR and ¹H‐NMR analyses. The optimized PUA oligomer/hydroxyethyl acrylate based polymerization system show a low viscosity, high storage stability and good compatibility with various functional segments. Furthermore, the modified PUA oligomer acts as both the photopolymerization constituent and the macromolecular co‐initiator assisting to achieve high photopolymerization rate and conversion rate, and avoiding the disadvantages caused by the migration of small amine co‐initiators. Benefitting from the semi‐IPN formed by this polymerization system with suitable crosslinking density and phase separation degree, a soft, strong and flexible cured film is obtained. The high photo‐reactivity with low viscosity of the polymerization system and the good flexibility with high strength of the resultant photo‐cured film ensures the applications of the modified PUA oligomer, and the printed fabrics achieve 4 grade of colorfastness with improved handle properties, as well as brilliant color and fine patterns.     

Novel polyurethane coating technology through glycidyl carbamate chemistry

Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins. Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol. The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate functional group is more reactive than a glycidyl ether group. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago, IL.     

Reactive blending approach to modify spin‐coated epoxy film: Part I. Synthesis and characterization of star‐shaped poly(ϵ‐caprolactone)

To effectively modify the properties of an epoxy, branched oligomers were synthesized from ?‐caprolactone (CL) and end‐functionalized to realize network precursors that can be reactively blended with the epoxy. The ring‐opening polymerization (ROP) of the CL in the presence of polyglycerol (PGL) initiator (3.9 and 9.1 mol %) and Sn(II) 2‐ethylhexanoate catalyst yielded oligomers with hydroxyl end‐groups, which were converted to carboxylic acid functionality by reaction with succinic anhydride. The functionalized oligomers had a four‐armed structure and the molecular weight of the oligomers could be controlled by the ratio of CL to PGL in the feed. To achieve an adequately crosslinked network in the reactive blending, a dual‐catalyzed reaction scheme was employed. First the oligomer was incorporated into the epoxy matrix in an imidazole‐catalyzed reaction and then the crosslinking was completed with an acid‐catalyzed ROP of the residual epoxies. Investigations showed that toughened coatings could be prepared from the inherently brittle epoxy through proper choice of the blending ratio of oligomer to epoxy. The blending increased surface hydrophobicity at high concentrations of functionalized oligomer, but did not have an adverse effect on the inherently advantageous endothelial cell spreading. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3677–3688, 2006     

Ultraviolet-photocurable oligomer. II. Syntheses and cured film properties of ultraviolet-photocurable BTDA-based caprolactone multiacrylate oligomers

A series of ultraviolet (UV)-photocurable 3,3′4,4′-benzophenone tetracarboxylic dianhydride (BTDA)-based multiacrylate oligomers containing pendant glycidyl methacrylate (GMA) or glycidyl acrylate (GA) and caprolactone acrylate (Tone M-100) or caprolactone methacrylate (Tone M-201) were synthesized. The effects of the acrylic functional groups, the moles of GMA, and the molar ratio of Tone M-201 to Tone M-100 on their properties were investigated. The prepared photocurable oligomers were cured rapidly when exposed to UV or sunlight radiation without the addition of any extra photoinitiator or photosensitizer. The acrylate-type oligomer resulted in a lower thermal curing temperature and a fast curing rate. Increasing the moles of GMA or the molar ratio of Tone M-201/Tone M-100 on reaction led to a higher crosslinking density and resulted in film with higher Young's modulus, higher breaking strength, and lower elongation. The methacrylate type oligomer cured to a very hard but brittle film with higher Young's modulus and lower elongation. By contrast, the acrylate-type oligomer cured to a hard, tough film with lower Young's modulus and higher elongation. The film properties of the oligomers coated on steel plates were also investigated. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 1625–1634, 1997     

Novel crosslinking system with hydroxyl-containing polymer, alicyclic polyepoxide and polyalkoxysilane

The crosslinking system based on the reaction among alicyclic epoxide group, hydroxyl group and alkoxysilyl group in the presence of aluminum β-diketone chelate have been developed. Five kinds of reaction are possible, and the result of gas chromatography and infrared analyses indicated that the main reaction is the ring-opening reaction of alicyclic epoxide group with hydroxyl group and/or hydroxysilyl group. The acrylic resin obtained by free radical polymerization of these three kinds of functional monomers and non-functional monomers showed good curing property, and the film was superior in acid rain resistance and outdoor durability. The resin is suitable to use in automotive 2coat–1bake clear coat. The viscosity of this binder system was remarkably reduced by addition of a low molecular weight alicyclic polyepoxide compound and an alkoxysilane oligomer without affecting to its good curing property. Such a system made it possible to design novel high solid coatings. It was found that the crosslinking could be extended to the combination of a polyester polyol, an alicyclic epoxide compound and an alkoxysilane oligomer. In this case, it was necessary that the polyester polyol contained highly reactive terminal hydroxyl group in the branch chains.     

Binder systems for waterborne two-pack products for car refinishes application

Waterborne (WB) products are of growing importance in the car refinishes market. Especially WB basecoats are gaining increased market share during the last couple of years. The introduction of WB two-pack primers, fillers, clearcoats and single stage topcoats is hampered, however due to the lack of suited binder systems.

In this paper, new approaches will be presented for two-pack binder systems. A number of topics will be discussed in more detail: the design of the binders, the involved chemistry, the incorporation of stabilizing and reactive groups, the functionality and miscibility of the hardener. Based on these variables, the most important properties have been studied: film formation, reactivity, potlife and paint properties like hardness, appearance and water and solvent resistance. During the investigation, model studies have also been applied.

It is shown that some binder systems offer very attractive features in which a number of properties can be tuned, e.g. amine-functional emulsions combined with acetoacetate-functional hardeners result in an excellent level of properties suited for primer/filler application.

These binder systems have been used as the starting points for product development that resulted in new prototypes of low VOC WB products with a very attractive overall performance.     

新型紫外线固化环氧树脂/丙烯酸酯改性水性聚氨酯的合成与性能

合成了一种新型的具有高交联密度和优异涂膜性能的环氧树脂和丙烯酸酯同时改性的紫外线（UV）固化水性聚氨酯（UV-EP-AC-WPUD）。通过环氧基团与以异氰酸酯基团（-N=C=O）封端的聚氨酯预聚体之间的反应引入质量分数为4%的环氧树脂E-20。同时,通过聚氨酯链的-N=C=O与二元丙烯酸酯（PEDA）以及季戊四醇三丙烯酸酯（PETA）的羟基之间的反应引入碳碳双键（C=C）,C=C的含量达到4.65 meq·g-1。 质量分数为3%的光引发剂Irgacure 2959被用于引发涂膜中C=C的聚合,涂膜的凝胶含量在12 s UV辐射之后达到91%,意味着C=C的聚合和交联速度快,同时所得到的涂膜的交联度非常高,不溶于溶剂丙酮,测试表明环氧树脂和两种丙烯酸酯单体已经成功嵌入聚氨酯链中,涂膜具有优异的力学性能和化学性能。     

Synthesis,characterization and self-crosslinking of glycidyl carbamate functional resins

Multifunctional glycidyl carbamate functional resins were synthesized, characterized, and self-crosslinked coatings were prepared and characterized. Coatings based on glycidyl carbamate (GC) functional oligomers are attractive because they combine polyurethane properties with epoxide reactivity. The glycidyl carbamate functional resins were synthesized via reactions of the biuret adduct and isocyanurate trimer of hexamethylene diisocyanate (HDI) with glycidol. Resins were characterized using gel permeation chromatography (GPC), Fourier transform infrared (FTIR) spectroscopy and ¹³C NMR spectroscopy. Coatings were prepared to study the self-crosslinking reaction without additional hardener. Self-crosslinked coatings had an excellent combination of solvent resistance, good hardness and high impact resistance. The glycidyl carbamate resin from the biuret isocyanate adduct (BGC) was found to be more reactive during cure than glycidyl carbamate from the isocyanurate isocyanate trimer (IGC) as determined by hardness, solvent resistance, and T_g measurements. Thermogravimetric analysis (TGA) of the resins did not show thermal decomposition below 250 °C.     

Deciphering the structure of itaconate‐based unsaturated polyester resins by high resolution mass spectrometry

Unsaturated polyester (UP) resins are widely used to manufacture composite materials and fulfil a wide panel of specification for industrial or domestic applications at low cost. These resins consist of a highly viscous polyester oligomer and a reactive diluent, which allow their processability and crosslinking. The oligomers are synthesized from diols and saturated or unsaturated diacids. Maleic anhydride is classically used as an unsaturated acid because of its reactivity for esterification and its competitive cost. However, maleic anhydride is petroleum based and classified as skin and respiratory sensitizing by the European Chemicals Agency. Itaconic acid which is recognized as one of the top 12 biobased molecules by the US Department of Energy is a biobased alternative with a reactive unsaturation. In this work, a UP based on propylene glycol, itaconic acid and dimethyl terephthalate was synthesized by polycondensation and characterized by high resolution mass spectroscopy, ¹H, ¹³C 1D and 2D NMR as well as ion mobility spectrometry mass spectrometry. The main structures were linear but cyclic species and a few branched chains due to the intermolecular Ordelt reaction were also detected by NMR and high resolution mass spectroscopy. Molecular modelling has indeed demonstrated that itaconate‐based UPs are more prone to cyclization than fumarate‐based UPs. Moreover, NMR analysis showed a significant consumption of itaconate unsaturation by the Ordelt reaction. Ion mobility spectrometry mass spectrometry allowed an additional structure to be distinguished for the same m/z peaks first attributed to a linear structure only. These results suggest the existence of cyclic species based on an intramolecular Ordelt reaction. © 2020 Society of Chemical Industry     

齐聚物对聚酯纺丝及拉膜的影响研究

选择了不同齐聚物含量的聚酯进行了拉膜和纺丝实验,研究齐聚物对聚酯后加工性能的影响。发现在拉膜过程中齐聚物的存在会导致高破膜率,影响薄膜产量和质量,在纺丝过程中齐聚物的存在容易导致组件压力上升、喷丝板堵塞、断头飞丝等情况,可纺性受到影响。     

Preparation and properties of photocurable unsaturated oligoester acrylourethanes

Syntheses of several photocurable resins and their properties before and after photocuring are investigated. Unsaturated oligoester acrylourethanes (IIIa–IIId) are prepared by addition reaction between four types of hydroxy-terminate unsaturated oligoesters (Ia–Id) and intermediate of adduct II. The former is prepared by addition-condensation reaction of glycols and maleic anhydride, while the latter is prepared from 2,4-TDI and equivalent HEMA by addition reaction in the presence of stannous octoate with THF as solvent. From the decrease of NCOs characteristic absorption peak at 2250 cm^?1 of IR spectrum, the conversions of the reaction of 2,4-TDI with HEMA and hydroxy-terminated unsaturated oligoesters were calculated. The unsaturated photocurable resins are compared with saturated oligomers (obtained by replacing maleic anhydride with succinic anhydride) with regard to curing rates and mechanical properties. Properties of pure oligomers are determined both before and after hardening. If added with reactive monomers, the oligomers thus cured are found to possess better properties than otherwise. Among the monomers, HEMA proves to be especially helpful in the increase of mechanical properties. Above all, combined use of IIIb oligomer and HEMA serves the best purpose for metal coating.     

水性醇酸树脂的合成及其耐水性的研究

以甘油、亚麻油酸、三羟甲基丙烷、邻苯二甲酸酐,间苯二甲酸及偏苯三酸酐等为原料合成了水性醇酸树脂,通过涂膜性能测试研究了反应温度、反应时间及偏苯三酸酐用量对水性醇酸树脂性能的影响。对比研究了氮丙啶型、硅氧烷型及多碳二亚胺型3种室温固化交联剂对水性醇酸树脂涂膜性能的影响。结果表明:水性化阶段偏苯三酸酐用量为10%,反应时间为1.5 h,反应温度为170 ℃时树脂性能较优。耐水性研究表明:加入硅氧烷型交联剂A后涂膜的耐水性最优,吸水率最低,当用量为6%时,清漆涂膜的硬度、光泽、附着力、耐水性、耐溶剂性均达到预期效果。加入辛酸亚锡后,涂膜在低温高湿环境下,干燥性及耐水性均得到明显改善。     

Acrylated polyurethanes by reactive extrusion

A one-step acrylated polyurethanes prepolymers synthesis by reactive extrusion and bulk reaction is discussed.These oligomers are obtained by a simultaneous reaction of MDI, polycaprolactone and hydroxyethyl-acrylate. In order to obtain a high reaction conversion within the extruder, tin laurate catalyst was used at 90°C. In these conditions, an appropriate radical initiator can be introduced during the extrusion without double bond polymerization. Comparing bulk and reactive extrusion prepared products, oligomer Tg were respectively 18°C and +8°C for oligomers and +18°C and +27°C for the issued networks.     

低温阴极电泳漆的制备及性能

随着人们对环境保护以及低能量消耗要求的不断提高,低温固化阴极电泳漆已经成为电泳漆的发展趋势之一。合成了封闭物异氰酸酯固化交联剂,并探讨了反应时间和反应温度对封闭率的影响,最后以氨化改性环氧树脂为基料树脂合成了低温固化阴极电泳漆。实验结果表明：在150℃／20min的固化条件下,漆膜能得到完全固化,经过漆膜综合性能实验,在选择合适的电泳工艺参数下,可以得到硬度较高、耐潮、耐盐、耐酸碱性能好的漆膜。     

Synthesis and characteristics of aqueous reactive urethane oligomer containing sulfoisophthalate sodium salt

This research studied urethane oligomers, which contains the sulfonic acid group and different reactive groups. First, the transesterification of dimethyl 5‐sulfoisophthalate sodium salt were performed with ethylene glycol or polyethylene glycol of different molecular weights to produce PEG soft chains possessing sulfonic acid group. Subsequently, isophorone diisocyanate used as a hard chain was connected to the two terminals of the sulfonated diols, which finally were blocked by methyl ethyl ketoxime or hydroxyethyl methacrylate or 2, 3‐Epoxy‐1‐propanol to form three kinds of aqueous reactive urethane oligomers (MSE, HSE, and OSE). The MSE oligomer had the greatest particle diameter, particle variance, and streaming current readings; the HSE oligomer, and the OSE oligomer had the second large and the smallest readings of the aforementioned measurements, respectively; whereas the contact angle and surface tension appeared with an opposite trend. Within the thermal properties of oligomer, the T_g of oligomer followed the trend: OSE < HSE < MSE; however, T_m and ΔH show an opposite tendency. With regard to the reactivity of the oligomers toward PET fabric, the add‐on for the variety of oligomers was in the quantity order of MSE > HSE > OSE series, and the washing durability was rated in the order of HSE > MSE > OSE series. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Synthesis of polybutadiene-acrylates and properties of the photocured films

The acrylation of polybutadienes was performed by reaction of acrylic acid with epoxy, epoxy-hydroxyl functionalized and hydroxyl-terminated oligomers. Some epoxy-functionalized oligomers were previously obtained by epoxidation of a liquid 1,4-polybutadiene. The properties of the acrylated products were affected by the oligomer type and the reaction procedure. The UV-curing of these products was studied by FTIR and thermal analyses, which showed the amorphous and rubbery nature of the resulting films. In some cases, the double bonds conversion was increased by a thermal post-curing, but the adhesion properties were strongly reduced. The swelling of the UV-cured films was studied by varying the solvent polarity. The mixtures of some polybutadiene-acrylates with a typical epoxy-acrylic resin gave highly cross-linked films showing a flexibilizing effect due to the polybutadiene oligomers which can act as reactive diluents.     

助交联剂在氢化丁腈橡胶中的应用研究

研究了添加不同用量的助交联剂齐聚酯和三甲基丙烯酸三羟甲基丙烷酯(TMPTMA)氢化丁腈橡胶的硫化特性、力学性能,并对比了两种助交联剂对氢化丁腈橡胶的硫化特性、力学性能、老化性能、高温拉伸性能、耐磨性能和加工性能的影响。结果表明：随着齐聚酯和TMPTMA含量的增加,橡胶的扭矩增大,硫化时间缩短;拉伸强度基本不变,硬度、100%定伸应力、撕裂强度逐渐提高,拉断伸长率、回弹性减小。与添加齐聚酯的橡胶相比,添加TMPTMA橡胶的扭矩较大,硫化时间较短;对比添加齐聚酯和TMPTMA的橡胶,它们的力学性能、老化性能、高温拉伸性能和耐磨性能都非常接近,可见它们在硫化过程中的作用原理相似。由橡胶加工分析仪可知,添加TMPTMA橡胶的储能模量较小,损耗因子较大。