Zur viskosimetrie von schnell vernetzenden epoxidharz-systemen

Crosslinking of epoxy resins (diglycidyl ether of bisphenol A) with anhydride of hexahydrophthalic acid resp. diaminodiphenyl methane was investigated by viscosimetry. The viscosity/time relations previously published could not be used and were replaced by a new approximation. The influence of liquid or solid accelerators and of fillers (quartz, calcite) on the crosslinking process was investigated and an additional acceleration was observed if calcite is present.     

Zur kinetik der Vernetzung von Epoxidharzen

The crosslinking of epoxy resins,—phenylglycidylether as a model system as well as monomers and oligomers of diglycidylether of bisphenol A and of hydantoine resins—, with acid anhydride in presence of amine accelerators has been investigated. Experimental methods used were chemical analysis, dilatometry and calorimetry. From the determination of the chemical yield resulted, that crosslinking of epoxy and anhydride is a zero order reaction, but for longer distances of reaction time different rate constants must be used, leading to large differences in the activation energies of the steps of crosslinking. From time dependant deviations of the anhydride conversion yield from stochiometry it was concluded, that at first an intermediate compound originates and the linking of these units in the network determines the second step of crosslinking.     

Studies on Cure Synergism. II,Effect of Diisopropyl Thiophosphoryl-N-Oxydiethylene Sulfenamide and Dibenzothiazyl Disulfide in the Vulcanization of NR

Thiazole sulfenamides as well as thiocarbamyl sulfenamides in the presence of dibenzothiazyl disulfide (MBTS) form synergistic combinations of rubber accelerators that provide technologically important rubber vulcanizates. The present investigation explores the feasibility of using thiophosphoryl sulfenamide with MBTS as a binary system of mutually activated accelerators in the vulcanization of rubber. The cure characteristics of the NR compound containing various proportions of diisopropyl thiophosphoryl-N-oxydiethylene sulfenamide (DIPTOS) and MBTS have been investigated keeping the total concentrations of the accelerators at 6 mmol per 100 rubber. The results indicated mutual activity of the mixed accelerators and significant enhancement of torque, modulus, and tensile strength of the resulting vulcanizates. The general character of the reaction of thiophosphoryl sulfenamide and MBTS has been established by replacing DIPTOS by diisopropylthiophosphoryl-N-cyclopentamethylene sulfenamide (DIPTCS), in the investigation. The mutual activity consequent upon the interaction of the accelerators can be demonstrated through isolation and identification of the reaction products formed in the early part of cure using the HPLC technique, which is also extremely helpful in explaining the cure behavior of the different stocks used in the investigation. The study reveals that diisopropylthiophosphoryl-2-benzothiazole disulfide (DIBDS), formed (in situ) as a result of interaction of DIPTOS and MBTS, plays an active part in improving the physical properties of NR vulcanizates. From the chemical analyses of the vulcanizates it is evident that the network structure obtained with the binary system of accelerators is highly rich in monosulfidic linkages that render the vulcanizates resistant to aging at 100°C.     

Quaternary phosphonium compounds as latent accelerators for anhydride-cured epoxy resins. I. Latency and cure characteristics

Quaternary phosphonium compounds have been found to be extremely effective latent accelerators for anhydride-cured bisphenol A epoxy resins; at concentrations from 0.01% to 0.25%, fast gel times are found in the temperature range of 135°–200°C combined with very good storage properties at ambient temperatures. Using these materials as accelerators, it is possible to formulate long-life, one-component epoxy resins. From gel time data, Arrhenius plots were made for some of these phosphonium compounds, and results indicate low activation energy values of the order of 16.1 kcal/mole. Reaction mechanisms are proposed to explain the effectiveness of these phosphonium compounds as latent accelerators. The initiation mechanism probably involves the formation of hydrogen-bonded phosphonium–epoxy or phosphonium–anhydride complexes which rearrange on the application of heat to form activated species resulting in polymerization of the epoxy–anhydride components. The transfer of a proton from the phosphonium complex(es) to other epoxy or anhydride molecules would appear to be the rate-determining step in this initiation mechanism. Comparison of other well-known accelerators used for the anhydride cure of bisphenol A epoxy resins shows quaternary phosphonium compounds to be among the most effective accelerators disclosed to date.     

Properties of polysulfide sealants of VITEF type

Results of determining the working life, tensile strength, elongation, and hardness as a function of the content of a vulcanization accelerator are reported. The following accelerators are studied: diphenylguanidine, phenyl-β-naphthylamine, and γ-aminopropyltriethoxysilane. Optimal ratios for each studied accelerator grade are established and its operating properties and hardness are determined. Results of testing of mechanical properties of polysulfide sealants with the use of new accelerators are shown. The reported results of experimental studies indicate that application of new vulcanization accelerators makes it possible to not only considerably increase the working life of sealants but also to control their mechanical properties in a required direction.     

Effects of curing accelerators on physical properties of epoxy molding compound (EMC)

The effects of various curing accelerators on the physical properties of epoxy molding compounds (EMCs) were investigated. Such properties as elasticities in rubbery and glassy regions, glass transition temperature, thermal expansion coefficient, and water absorption at 60°C of neat epoxy resins using various curing accelerators were found to be directly reflected in the properties of the EMCs that were prepared by using each resin system. However, volume resistivity and saturated water absorption at 120°C were not reflected. This was attributed to differences in the catalytic reactivity of accelerators causing different melt viscosity for the EMC, which resulted in different densities (packing degrees) and affected physical properties of molded EMC. On the other hand, it was found that the density of molded EMC was also affected by the molding conditions. To improve the physical properties of the molded EMC, in addition to proper selection of accelerators, it was very important to set the melt viscosity of the EMC as high as possible within the moldable range and to select suitable molding conditions.     

酸酐固化环氧树脂用促进剂评述

评述了几类用于酸酐固化环氧树脂的促进剂及其在酸酐/环氧体系中的固化促进机理。同时,简要介绍了促进剂的研究进展。     

固化环氧树脂用促进剂

本文综述了胺或酸酐固化环氧树脂用的各种促进剂及其在固化环氧树脂体系中的催化促进机理.促进剂方面的新进展也进行了简要的介绍。     

Behavior of zinc complex of bis(N-phenylsulfonyldithiocarbimate) as accelerator in the vulcanization of nitrile rubber compounds

Chemical complexes containing N-R-sulfonyldithiocarbimates have been looked at as potential substitutes for N-R-dithiocarbamates as accelerators for the vulcanization process, especially due to their structural similarities and, most importantly, for the capability of this last compound to not form nitrosamines during the vulcanization process. The zinc complex bis(N-phenylsulfonyldithiocarbimate)zincate(II) (n-PSC) of tetrabutylammonium was tested in nitrile rubber compositions and its performance compared with bis(4-methylphenylsulfonyldithiocarbimate)zincate(II) (MPSC) of tetrabutylammonium and also with commercial accelerators. The complex n-PSC imparted values of cure times intermediate between those given by ultrafast and moderate commercial accelerators. Nitrile rubber compounded with n-PSC also presented similar mechanical properties as compared with the commercial accelerators except for an inferior aging resistance. Concerning the two complexes, n-PSC was found to promote better properties such as optimum cure time, crosslink density, and elongation at break as compared with MPSC. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47211.     

Untersuchungen über die Erstarrungseigenschaften von Fetten und Fettprodukten nach dem TRG-Verfahren

Studies on the Solidification Properties of Fats and Fat Products Using TRG-Procedure Solidification of a molten fat is a highly complex process, which can only be inadequately followed by conventional procedures. Using the TRG-method, it is possible to clearly follow the course of solidification along a curve recorded by the instrument and measure it quantitatively. The TRG-procedure provides practical guides on the qualitative properties of a fat and their impact on fat recipes and additives. Microcrystalline triglycerides of pure fatty acids are suitable solidification accelerators, which are added to the molten fat in the form of fine solid particles; they reduce the solidification time considerably, even if added in very small amounts.     

N‐benzoyl‐N′N′‐disubstituted thioureas—A new binary accelerator system and its effect of nucleophilicity in sulfur vulcanization of natural rubber

The effect of several new binary accelerator systems were studied with special emphasis to the relationship of nucleophilicity to their rheological and mechanical properties. In this study, dialkyl/azacycloalkyl substituted benzoylthioureas (BTU 1‐5) were used as secondary accelerators (SA) along with three different primary accelerators (PA) viz., Cyclohexylbenzthiazylsulfonamide (CBS), Mercaptobenzothiazole (MBT) or Zincdithiocarbamate(ZDC) in the sulfur vulcanization of natural rubber. The effect of these secondary accelerators on the rheological and mechanical properties was found to be improved when compared to the reference mixes. It is noted that the N‐benzoyl‐N′N′‐piperidinylthiourea (BTU 4) is more effective as a secondary accelerator due to the higher nucleophilicity of the same when compared with the test compounds. The ZDC‐BTU gives the best result as binary accelerator system in natural rubber. Chemical characterization was carried out by determining the total crosslink density. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

橡胶促进剂NS的绿色合成工艺与应用研究进展

橡胶硫化促进剂按照化学结构可以分为醛胺类、秋兰姆类、硫脲类、二硫代氨基甲酸盐类、噻唑类、胍类、黄原酸盐类和次磺酰胺类等,其中次磺酰胺类促进剂具有抗烧焦时间长、硫化活性大、硫化平坦性高、力学性能优良等优点,应用最为广泛。促进剂NS（N-叔丁基-2-苯并噻唑次磺酰胺,TBBS）与其他次磺酰胺类促进剂相比,因在硫化过程中不产生致癌毒性物质亚硝胺,被誉为“标准促进剂”。本文回顾了以次氯酸钠为氧化剂合成促进剂NS的传统方法;综述了催化氧化法、氯气氧化法、电解氧化法和双氧水氧化法等绿色合成工艺;简要概述了微通道反应器在合成促进剂NS方面的工业应用。同时简介了促进剂NS在天然橡胶、丁苯橡胶、二氧化硅填充橡胶的改性剂以及合成氨基磷酸酯等领域的应用。     

固化促进剂在耐候粉末涂料用聚酯树脂中的应用研究

研究了耐候粉末涂料用聚酯树脂合成中固化促进剂的作用;讨论了固化促进剂的选择、加入量、加入时机对树脂性能及涂层固化性能的影响;分析了固化促进剂对不同配方聚酯合成的影响。     

Accelerated cure of phenol–formaldehyde resins: Studies with model compounds

2‐Hydroxymethylphenol (2‐HMP) and 4‐hydroxymethylphenol (4‐HMP) were used as model compounds to study the reactions that occur during cure of phenol–formaldehyde (PF) resin to which cure accelerators (ethyl formate, propylene carbonate, γ‐butyrolactone, and triacetin) have been added. The addition of cure accelerators significantly increased the rate of condensation reactions. The cure accelerators were consumed during the reaction, indicating that they do not act as true catalysts. Major dimeric and trimeric reaction products were isolated and their structures determined. The results are consistent with a mechanism in which the hydroxymethyl group of 2‐HMP (or 4‐HMP) is first transesterified by the cure accelerator. The ester group is then displaced by reaction with the negatively charged ortho or para position of a second molecule (S_N2 mechanism) or is converted to a reactive quinone methide intermediate, which subsequently reacts with the negatively charged ortho or para position of a second molecule (quinone methide mechanism). When accelerators were added to the reaction mixture, the self‐condensation of 2‐HMP was faster than that of 4‐HMP. As is well documented in the literature, the exact opposite is true without added accelerators. This result would seem to indicate that the phenolic oxygen helps activate the esterified ortho‐hydroxymethyl group. The number and nature of crosslinks in a PF resin cured with added cure accelerator might be different than those in a PF resin cured without an added cure accelerator. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3256–3263, 2002     

化学镀镍的渗氢测量

介绍了一种适用于化学镀镍工艺的渗氢测量方法，可用于监控渗氢速度，测定氢在金属中的扩散，研究氢脆，评估腐蚀阻化剂和酸洗中钢铁的吸氢等方面。化学镀应用中经常要使用加速剂，本研究的目标物质是化学镀镍的加速荆——硫脲及其衍生物。在这些物质存在下，化学镀镍过程中的渗氢行为不同。良好的加速剂可减少氢渗，加快金属的覆盖。     

橡胶硫化促进剂的研究进展

概述了橡胶硫化促进剂的结构、类型、性能以及橡胶硫化反应机理的研究进展、硫化促进剂的性能表征方法。指出了国内外硫化促进剂的发展趋势。     

环氧树脂中温固化促进剂评述

本文概述了取代脲、咪唑盐、有机金属化合物和含磷化合物等四种环氧中温固化体系促进剂的特点、催化反应机理和应用情况。     

我国橡胶防老剂和促进剂的进出口情况

介绍近年来我国橡胶防老剂和促进剂进出口情况。2013年,我国防老剂和促进剂进口量分别为19046.61 t和14984.44 t,同比分别增长16.12%和11.64%;进口金额分别为6202.02万美元和7391.97万美元,同比分别增长14.76%和1.39%;出口量分别为29070.40 t和89942.59 t,同比分别增长62.68%和45.72%;出口金额分别为6794.43万美元和27885.34万美元,同比分别增长60.45%和50.17%。我国进口防老剂主要来自中国大陆(以国货复进口形式进口)、美国、韩国以及中国台湾省等,进口促进剂主要来自中国台湾省、美国、韩国、日本以及德国等,防老剂主要出口日本、泰国、印度尼西亚和韩国等,促进剂主要出口美国、韩国、巴西、泰国和日本等。     

Studies on the reactions between thiocarbamyl sulfenamide and 2-(iminodithio)benzothiazole accelerator system in the early stage of vulcanization of NR

Investigations on the interactions of the synergistic pair of accelerators comprising of thiocarbamyl sulfenamide and 2-(iminodithio)benzothiazole have been carried out through hplc. N-cyclopentamethylene thiocarbamyl-N'-oxydiethylene sulfenamide, N-oxydiethylenethiocarbamyl-N'-cyclopentamethylene sulfenamide (OTCS), 2-morpholinodithiobenzothiazole, and 2-piperidinodithiobenzothiazole (PDB) have been selected as the reactants which, when suitably combined, provide most effective accelerator systems capable of generating heat and age resistant vulcanizates. The OTCS–PDB system has been found to yield vulcanizates which exhibit the greatest crosslink density, scorch safety, and highest modulus and tensile strength. An attempt has been made to explain the higher activity of the binary systems studied as compared to that obtained from comparable thiocarbamyl sulfenamide plus dibenzothiazyl disulfide system. Zin–dithiocarbamates have been found to influence the curing reactions depending upon the composition of the mixed accelerators. Cyclohexyl thiophthalimide, a versatile cure retarder, reacts with the accelerators to yield cyclohexyl thiomorpholine and cyclohexyl thiopiperidine, as the case may, which also have a profound effect upon cure retardation as noticed in the present investigation.     

硫化胶中次磺酰胺类促进剂的鉴定

用高分辨及高度灵敏的裂解毛细管气相色谱－硫选择检测器和衍生－毛细管气相色谱联用分析技术，以添加了促进剂ＣＺ，ＮＯＢＳ，ＮＳ，ＤＺ的硫化胶为研究对象，进行了硫化胶中次磺酰胺类促进剂母体苯并噻唑及上述促进剂相应的残留胺的测定，然后综合两步的分析结果，准确有效地从硫化胺中鉴定出了上述４种次磺酰胺类促进剂。