低温光-热双重固化材料的制备及其性能研究

合成了既可以光固化又可以热固化的环氧丙烯酸酯,合成的树脂加入引发剂和促进剂后不仅在紫外光辐射下可以快速固化,而且仅在50℃加热的条件下也可在1 h内达到表干;研究了涂膜在单独光固化、单独热固化时固化涂膜的性能及其影响因素;红外光谱表明无论是光固化还是热固化,涂膜的固化程度均较高,凝胶含量可达到90.34%,且热重分析显示涂膜耐热性能良好。     

紫外光固胶粘剂用促进剂的合成及应用

采用丙烯酸羟乙酯与五氧化二磷为原料制得了促进剂以改善紫外光固化胶粘剂的粘接性能。研究了丙烯酸酯种类对促进剂性能以及促进剂用量对胶粘剂固化时间和剪切强度的影响。结果表明,加入质量分数3%~4%磷酸酯促进剂可以有效缩短紫外光固胶粘剂的固化时间并提高粘接强度。     

适用于低温固化环境的环氧树脂体系的选择

环氧固化体系的干燥时间与固化促进剂用量以及固化的环境温度密切相关。随着固化促进剂用量的增加,体系的干燥性能逐步得到提升。本文解析了固化促进剂DMP-30的作用机理并用红外谱图法表征了微观反应过程,并且通过对DMP-30在-15℃到5℃的低温固化条件下对环氧固化体系干燥性能的影响,以及不同的DMP-30加入量对体系机械性能影响的研究,结合考察环氧活性稀释剂对降低环氧固化体系粘度的作用,最终得出了环氧体系中较为合适的环氧促进剂加入量和环氧稀释剂的种类。     

户内热转印粉末涂料用混合型聚酯树脂的合成研究

通过分析热转印性能的影响因素合成了不同结构的聚酯树脂,研究了树脂酸值对热转印性能的影响,同时研究了部分单体对聚酯树脂热转印性能的影响。采用 DSC热分析法研究了固化促进剂对粉末涂料固化行为的影响,结果表明：选择合适的固化促进剂对涂层转印性能的提高有至关重要的作用。     

室温固化环氧胶粘剂的研究

开发了一种室温固化环氧二聚酰胺胶粘剂．文中介绍了胶的配方、基本性能、耐介质性能和耐老化性能等。讨论了环氧树脂与聚酰胺比例的确定．加入少量液体芳胺对胶性能的影响．以及固化剂、固化促进剂和固化时间对胶性能的影响等．     

潜伏性环氧树脂固化促进剂M-Cd的合成及其应用

采用间苯二胺和溴化镉合成了一种具有潜伏性的环氧树脂固化促进剂M－Cd它是一种络合物，将它应用于二氰二胺／环氧树脂脂固化体系的高温结构粘剂中，能够显著地降低粘剂的固化温度，缩短固化时间，本文还讨论了合成该促进剂主要成分的投料比，应用于二氰二胺／环氧树脂固化体系的高温结构胶粘剂中该促进剂的使用量以及固化条件对粘剂力学性能的影响，同时还考核了应用该促进剂M的高温结构胶粘剂的综合性能。     

AlCl3络合物对酚醛树脂固化反应的影响

以苯酚和甲醛为原料合成热固性酚醛树脂,并添加聚乙烯醇缩丁醛（PVB）对酚醛树脂增韧,研究了固化促进剂AlCl3络合物对增韧后酚醛树脂的固化行为和热力学性能的影响。结果表明,加入聚乙烯醇缩丁醛后剪切强度呈现先增后降的趋势,添加20%聚乙烯醇缩丁醛后剪切强度达到最大,增韧后酚醛树脂加入2%固化促进剂后固化时间明显缩短且固化程度略有提高,并用DSC、TG、IR对其固化反应及固化物进行分析表征。     

中密度纤维板(MDF)粉末涂料低温固化技术研究

为了制备中密度纤维板(MDF)用低温固化粉末涂料,合成了一种液体叔胺促进剂,成功使聚酯/环氧粉末涂料在130℃,3 min条件下快速固化,并研究了促进剂用量对粉末涂料固化及涂层性能的影响,利用差示扫描量热仪(DSC)、红外光谱仪(FI-IR)对涂膜固化行为进行了分析:结果显示:促进剂用量提高可以有效降低固化温度和加快固化反应速率,促进剂的最佳用量为2 g时,固化后的涂层与底材结合力高.具有优异的机械性能和耐化学品性。DSC和红外光谱分析结果表明所制备的粉末涂料具备优异的低温固化性能,固化温度低于130℃。     

中密度纤维板(MDF)粉末涂料低温固化技术研究

为了制备中密度纤维板(MDF)用低温固化粉末涂料,合成了一种液体叔胺促进剂,成功使聚酯/环氧粉末涂料在130℃,3 min条件下快速固化,并研究了促进剂用量对粉末涂料固化及涂层性能的影响,利用差示扫描量热仪(DSC)、红外光谱仪(FI-IR)对涂膜固化行为进行了分析:结果显示:促进剂用量提高可以有效降低固化温度和加快固化反应速率,促进剂的最佳用量为2 g时,固化后的涂层与底材结合力高.具有优异的机械性能和耐化学品性。DSC和红外光谱分析结果表明所制备的粉末涂料具备优异的低温固化性能,固化温度低于130℃。     

苯甲酸缩水甘油酯固化型聚酯树脂的合成与性能研究

合成了一种适用于多元苯甲酸缩水甘油酯(PT910)固化的粉末涂料用聚酯树脂,分别讨论了固化剂对粉末涂料玻璃化温度(Tg)的影响、原材料2,6-萘二甲酸(NDA)对聚酯树脂Tg的影响、聚酯合成酸解封端剂对粉末涂料固化活性的影响、树脂黏度对涂料性能以及固化促进剂的影响。     

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。     

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     

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.     

Effect of various efficient vulcanization cure systems on the compression set of a nitrile rubber filled with different fillers

Effect of various efficient vulcanization (EV) sulfur cure systems on the compression set of a nitrile rubber filled with carbon black and silica/silane fillers was examined. The cure systems had different amounts of thiuram and sulfenamide accelerators and elemental sulfur, whilst the loading of zinc oxide and stearic acid activators was kept constant. The fillers had surface areas from 35 to 175 m²/g. In this study, the lowest compression set was measured for the rubber filled with carbon black with 78 m²/g surface area, which was cured with an EV cure system made of a small amount of elemental sulfur and large amounts of the two accelerators. Interestingly, a small change in the amount of elemental sulfur had a bigger effect on the compression set than did large changes in the loading of the accelerators in the cure system. Among the fillers, carbon black caused less compression set of the rubber vulcanizate than the silica/silane system did. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41512.     

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.     

Zur Häurtung von Bisphenol-A-diglycidether mit Dicyandiamid in Gegenwart von Beschleuniger-Addukten

Single-component formulations of epoxy resins with reactive accelerators must be storable. The preparation of several blocked accelerators is described. The basicity of tertiary amines, which correlates with accelerating effects, as well as acidity and structure of polyphenols and modified novolacs influences the extend of blocking. The curing process was investigated by measurements of gel time and viscosity.     

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.     

Acetylacetonates of nickel(II) and copper(II) as accelerators for the epoxy resin system

The acetylacetonates of nickel(II) and copper(II) serve as accelerators for the anhydridecurable epoxy resin system. An appreciable lowering in the cure gel time and a substantial increase in the rate of curing is observed with enhanced concentrations of the metal chelates. Cure kinetic studies and cure schedules have been followed using a differential scanning calorimeter. The thermal and electrical insulation characteristics of the cured epoxy system are little affected by the variation of temperature, voltage, and aging under UV radiation. © 1994 John Wiley & Sons, Inc.     

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.     

The chemistry of sulfur curing. Part II. Kinetics of vulcanization of an EPDM elastomer accelerated by tetramethylthiuram monosulfide and disulfide

The induction periods and maximum cure rates of an EPDM gum rubber were determined by using the Monsanto oscillating disk rheometer and correlated against the initial concentrations of curing ingredients. Sulfur curing systems accelerated by TMTM and TMTD were used. The maximum cure rates of the TMTM-accelerated and the TMTD-accelerated EPDM terpolymer compounds differed significantly only at low sulfur concentrations where the TMTM-accelerated compounds had slower maximum cure rates. Above approximately the 1% concentration level, TMTM and TMTD were found increasingly to retard the maximum cure rates of the EPDM terpolymer compounds as the initial concentrations of the thiuram accelerators were increased. The maximum cure rates of the TMTM-and TMTD-accelerated terpolymer compounds were found to be variable order in initial accelerator concentration, second-order in initial cure site concentration, approximately half-order in initial sulfur concentration above 0.3% sulfur, and of a positive variable order in initial zinc oxide concentration.