Studies on Performance of Cured Water-Borne Melamine–Acrylic Emulsion Coatings

In this study, water-borne coating formulations which could be cured quickly were prepared using acrylic emulsion as the major coating constituent and highly reactive melamine resin as curing agent, and further incorporating a variety of additives. Melamine and acrylic types, melamine/acrylic mass ratio in coating formulation, and curing temperature were found to influence the performance of cured coatings. When melamine resin etherified slightly with methanol was used as curing agent, melamine/acrylic mass ratio was 0.45 and the coating formulation was baked at 170°C for 30 s, it was observed that performance of cured coating was the best. FTIR was used to study molecular structural changes of coatings after curing, and to analyze the cure mechanism of the coating. DSC was used to study the range of temperature in which curing occurred. The water-borne coating prepared in this study could be cured quickly when it was applied on decorative paper surface and baked at high temperature. Performance properties of cured coatings were tested according to standard methods, it was observed that dry heat resistance, wet heat resistance, adhesion, pencil hardness, and stain resistance all met standard requirements.     

酶解木质素改性三聚氰胺脲醛树脂的制备与应用

以酶解木质素（EL）、尿素（U）、甲醛（F）和三聚氰胺（M）为原料,采用碱反应工艺制备了酶解木质素改性三聚氰胺脲醛树脂（ELMUF）。分别考查了EL用量对制备的ELMUF树脂的固化时间、固化温度、游离甲醛量及其制备胶合板胶合强度和甲醛释放量等性能的影响,随着EL用量的增加,ELMUF树脂游离甲醛量从0.26%逐渐降低至0.12%,固化时间从96 s逐渐延长至152 s,黏度由86 mPa·s迅速升高至1 140 mPa·s。通过DSC测定不同EL用量的脲醛树脂固化过程,结果表明：随着EL用量的增加脲醛树脂的反应活性逐渐降低,固化温度由120.6℃逐渐升高至132.0℃,对热压工艺要求更加苛刻。     

密胺树脂硫磺微胶囊的制备及应用

针对橡胶硫化中的"喷霜"和橡胶裂纹的自修复问题,以升华硫为芯材,密胺树脂(PMF)为壳材,采用原位聚合法制备了密胺树脂硫磺微胶囊.研究了密胺树脂的缩聚pH值对微胶囊形态的影响,乳化剂浓度、芯材含量对微胶囊粒径的影响以及密胺树脂的缩聚pH值、液固相比(w/s)、甲醛和密胺的摩尔比对微胶囊包覆率的影响.结果表明:密胺树脂的...     

A Novel Type of Organo Clay Containing Alkyd-Melamine Formaldehyde Resins

In this study, organo clay-modified alkyd resins were synthesized and these modified alkyd resins were cured with different ratios of melamine formaldehyde resin for the first time. Alkyd resins were blended with 30% and 40% of a commercial melamine-formaldehyde resin. Alkyd-melamine formaldehyde resin films were cured at 140°C for 2 h in an oven. The effect of organo clay addition on the physical and chemical film properties was investigated. These surface coating properties of the resins enhanced with amount of organo clay up to 2–3%. These resins are suitable for manufacturing of high-performance industrial baking enamels.     

甲醛/三聚氰胺配比对三聚氰胺甲醛泡沫塑料性能的影响研究

三聚氰胺和甲醛在温度为85～95℃、氢氧化钠为催化剂、持续反应3～4h的条件下,可反应生成一种固含量≥65%、化学性能相对稳定的三聚氰胺甲醛树脂。以这种树脂为基体,加入乳化剂、固化剂和发泡剂,经发泡工艺制备出三聚氰胺甲醛泡沫塑料。研究了甲醛/三聚氰胺的摩尔配比(F/M)对可发性三聚氰胺甲醛树脂的物理性能、有毒物质残余量、机械性能的影响,以及与树脂可发性的关系。结果表明,当F/M=3.0时,可发性三聚氰胺甲醛树脂的固含量为69%;黏度为1 280 mPa.s;抗弯曲强度为305.6 kPa;氧指数为40.5%;热释放速率为0.15 kW/m2;烟灰产率仅为2.1 m2/m2;峰值CO产量为0.0292 kg/kg。     

Differential scanning calorimetric examination of melamine–formaldehyde microcapsules containing decane

The main objective of this study was to investigate the composition of microcapsules and the degree of curing of melamine–formaldehyde (MF) resin, which formed a shell of microcapsules, by the use of differential dynamic calorimetry (DSC). For this purpose, decane was chosen as core material. The microencapsulation of decane with MF resin was carried out at different temperatures and pH values. The temperature and pH value were kept constant during the process. The composition of the microcapsules and the degree of curing of the shell material were studied during and after the microencapsulation process. DSC analysis, in combination with scanning electron microscopy analysis, was revealed as an effective tool for the investigation of the microencapsulation process with MF resin. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

三聚氰胺添加方式对MUF胶粘剂性能的影响

以三聚氰胺作为脲醛树脂(UF)的共聚改性剂制备MUF(三聚氰胺甲醛树脂)胶粘剂。探讨了三聚氰胺的添加方式对MUF胶粘剂性能的影响,同时对其固化特性、分子结构和耐热性等进行了分析。结果表明:三聚氰胺2次投料法可有效降低MUF胶粘剂的甲醛释放量,但其胶接强度也随之下降;同时,该MUF固化体系的外推固化温度、表观活化能和反应级数均有所增加,耐热性降低;另外,2次投料体系使MUF的相对分子质量降低、相对分子质量分布变宽。     

氨基树脂改性聚醚多元醇的合成及残留甲醛的去除

以三聚氰胺、尿素、甲醛溶液、高活性聚醚多元醇为原料合成了氨基树脂改性聚醚多元醇。讨论了甲醛、三聚氰胺投料比对改性聚醚多元醇稳定性的影响,确定了减压脱除甲醛的最佳条件,对比了不同甲醛去除剂的除醛效果,并考察了改性聚醚多元醇的阻燃效果。结果表明,当甲醛与三聚氰胺投料摩尔比确定为4．5时,合成的改性聚醚多元醇稳定性最好;改性聚醚多元醇减压脱醛温度控制为100～120℃,时间为8h,可达到最佳脱醛效果;结合减压脱醛处理,再先后用氧化剂、甲醛捕捉剂和光触媒的分别处理可将制成高回弹聚氨酯泡沫的甲醛量降低至16mg／kg;以改性聚醚多元醇制成的高回弹聚氨酯泡沫氧指数达到27％,最大烟密度值为4．11。     

三聚氰胺草酸盐与氯化铵作为UF固化剂的性能对比

以三聚氰胺草酸盐(MOX)和氯化铵分别作为脲醛树脂(UF)的固化剂,然后以相应的改性UF胶粘剂压制胶合板,并探讨了不同固化剂对UF的固化时间、胶合板的胶接强度和甲醛释放量等影响。结果表明:以MOX作为固化剂时,相应UF的固化速率相对较慢,由该改性UF胶粘剂压制而成的胶合板,其胶接强度相对较高,甲醛释放量略高于含氯化铵体系;含MOX固化剂的UF胶粘剂,其DSC曲线峰顶温度(86.22℃)和吸热量(51.14 J/mg)低于含氯化铵体系,并且含MOX体系的固化反应比较平稳。     

A Study on Composites from Casein Modified Melamine-Formaldehyde Resin

Amino resins are used for various applications such as decorative plastic plates, decorative wood boards, particle boards, leather tanning, foam, coating, and molding materials. In the present work, it was planned to prepare modified melamine-formaldehyde resin by incorporating casein. The intended melamine-formaldehyde-casein (MFC) resin samples were prepared under alkaline condition with an 1:3 melamine: formaldehyde ratio. Casein was incorporated in varying proportions (up to 25% w/w of melamine content) at 85–90°C. The samples were characterized by viscosity measurement and vapor pressure osmometry (VPO). The resin samples were cured isothermally at 60°C using ammonium chloride as well as hydroxylamine hydrochloride and at 120°C using hexamine as the curing agents. Jute fabric (JFRC) and glass fabric reinforced composites (GFRC) were produced by maintaining 60:40 and 40:60 proportion of resin to reinforcement materials, respectively. The laminates thus formed were characterized for their mechanical properties and chemical resistance.     

Semiconductive polyaniline melamine–formaldehyde blend electronic barrier to corrosion

Abstract

Polyaniline (PANI) is one of the intrinsic semiconductive polymers and shows some useful properties: high conductivity, transparency for the red and violet domain of spectrum, good elasticity and processability, superficial tension and chemical, photochemical and electrochemical behaviour. A PANI primer coat has been developed to act as an active electronic barrier to corrosion. When overlaid with a conventional durable topcoat, the coating has been shown to protect steel against salt, pollutants and other harsh environments.

Dry blends were prepared by blending the powders of doped PANI and the host polymer, a commercial melamine–formaldehyde resin AZAMIN M514 in a mixer. The hardness, elasticity, resistance and protective behaviour of melamine–formaldehyde resin films were determined. The protective behaviour of obtained melamine–formaldehyde resin blend was evaluated from quantity of Fe (II) released by the coated carbon steel samples (exposed area 1·0 cm^–2) immersed for 1 month in 50 mL 3·5%NaCl solutions. The prepared coatings protect substrate from corrosion by stabilising the oxide layer formed on the metal surface and thus prevent the metal dissolution process. An optimum formulation of melamine–formaldehyde resin coatings with 5 wt-% doped PANI exhibits good protective behaviour.     

Preparation and curing of alkyd based on ricinoleic acid/melamine coatings

Three alkyd resins of high hydroxyl numbers based on ricinoleic acid, phthalic anhydride and glycerin, trimethylolpropane or ethoxylated pentaerythritol as polyol were prepared. Afterwards synthesized alkyds were made into baking enamels by blending with commercial melamine-formaldehyde resins (weight ratio of 70:30 based on dried mass). Alkyd/melamine resin mixtures were cured in a differential scanning calorimeter (DSC) under non-isothermal mode. Apparent degree of curing as a function of temperature was calculated from the curing enthalpies. Fourier transform infrared spectroscopy (FTIR) was used to identify characteristic peaks of resin mixtures before and after being cured. The gel content, hardness, elasticity and impact resistance of coated film cured at 150 °C for 60 min were measured. The onset of film thermal degradation, determined by thermogravimetric analysis (TGA) was observed at the temperatures from 281 to 330 °C. Based on the results obtained we suppose that the combinations of synthesized alkyds based on ricinoleic acid with used melamine resins could be employed as the compositions for the preparation of baking enamels.     

Evaluation of melamine‐modified urea‐formaldehyde resins as particleboard binders

Particleboards bonded with 6 and 12% melamine‐modified urea‐formaldehyde (UMF) resins were manufactured using two different press temperatures and press times and the mechanical properties, water resistance, and formaldehyde emission (FE) values of boards were measured in comparison to a typical urea‐formaldehyde (UF) resin as control. The formaldehyde/(urea + melamine) (F/(U + M)) mole ratio of UMF resins and F/U mole ratio of UF resins were 1.05, 1.15, and 1.25 that encompass the current industrial values near 1.15. UMF resins exhibited better physical properties, higher water resistance, and lower FE values of boards than UF resin control for all F/(U + M) mole ratios tested. Therefore, addition of melamine at these levels can provide lower FE and maintain the physical properties of boards. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Flexible epoxy novolac coatings: Use of cardanol‐based flexibilizers

Flexible epoxy novolac coatings were developed by reacting an epoxy novolac resin, poly[(phenylglycidyl ether)‐co‐formaldehyde] (PPGEF) with an amine curing agent, 4,4′‐diamino‐3,3′‐dimethyldicyclohexyl methane (BMCHA), cardanol based reactive diluent (Cardolite NC‐513) and two different cardanol‐based flexibilizers (Cardolite NC‐514 and Cardolite NC‐547). The flexibilizer content was varied from 5 to 10% by weight of the resin. These resins were coated onto the stainless steel panels and tested for their gloss, cross‐hatch adhesion, falling weight impact resistance, flexibility, abrasion, scratch hardness, solvent scrub resistance, and chemical resistance. The thermo‐mechanical properties of these coatings were determined by TGA, DSC, DMTA, and tensile strength measurements. The cryofractured specimens were subjected to SEM analysis. The influence of structural differences of two flexibilizers on the coating properties was investigated. These coatings exhibited excellent properties and have great potential in industrial applications. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44920.     

Curing of low level melamine‐modified urea‐formaldehyde particleboard binder resins studied with dynamic mechanical analysis (DMA)

Effects of resin formulation, catalyst, and curing temperature were studied for particleboard binder‐type urea‐formaldehyde (UF) and 6 ～ 12% melamine‐modified urea‐melamine‐formaldehyde (UMF) resins using the dynamic mechanical analysis method at 125 ～ 160°C. In general, the UF and UMF resins gelled and, after a relatively long low modulus period, rapidly vitrified. The gel times shortened as the catalyst level and resin mix time increased. The cure slope of the vitrification stage decreased as the catalyst mix time increased, perhaps because of the deleterious effects of polymer advancements incurred before curing. For UMF resins, the higher extent of polymerization effected for UF base resin in resin synthesis increased the cure slope of vitrification. The cure times taken to reach the vitrification were longer for UMF resins than UF resins and increased with increased melamine levels. The thermal stability and rigidity of cured UMF resins were higher than those of UF resins and also higher for resins with higher melamine levels, to indicate the possibility of bonding particleboard with improved bond strength and lower formaldehyde emission. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 377–389, 2005     

丁腈橡胶与尼龙织物的粘接

本文叙述了弹性体——间苯二酚甲醛树脂胶粘剂的组成,胶粘剂涂层厚度以及固化压力对丁腈橡胶与尼龙织物粘接的影响。文章还介绍了蜜胺衍生物作为无刺激性气味的甲醛给予体对粘接性能的影响。     

Properties of plywood panels bonded with ionic liquid-modified lignin–phenol–formaldehyde resin

The aim of this research was to investigate the physical and mechanical properties of plywood panels bonded with ionic liquid-modified lignin–phenol–formaldehyde (LPF) resin. For this purpose, soda bagasse lignin was modified by 1-ethyl-3-methylimidazolium acetate ([Emim][OAc]) ionic liquid, and then, various contents of modified lignins (10, 15, and 20 wt%) were added as a substitute of phenol in phenol–formaldehyde (PF) resin synthesis. The properties of the synthesized resin were compared with those of a control PF resin. The changes in curing behavior of the resins prepared were analyzed by differential scanning calorimetry (DSC). The physical properties of the resins prepared, as well as the water absorption, thickness swelling, shear strength, and formaldehyde emission of the plywood panels bonded with these adhesives, were measured according to standard methods. DSC analysis indicated that in comparison with PF resins, curing of the LPF resin occurred at lower temperatures. The physical properties of the synthesized resins indicated that viscosity and solid content increased, while gel time and density decreased by addition of treated lignin to the PF resin. Although the panels containing resins with modified lignin yielded low formaldehyde emission, their dimensional stability was worse than those bonded with a commercial PF adhesive. The plywood prepared using IL-treated lignin PF resins has shear strength, which satisfy the requirements of the relevant standards specifications and significantly better than that of panels prepared with the control PF resin. The mechanical properties of the panels could be significantly enhanced with increased percentage of treated lignin content from 0 to 20 wt%.     

发泡剂对三聚氰胺甲醛泡沫塑料性能的影响

用多聚甲醛代替部分甲醛溶液,与三聚氰胺在pH值为8.5～9.5、温度在85℃条件下发生羟甲基化反应,制备固含量≥65%的树脂,加入固化剂和乳化剂,用发泡剂进行发泡,讨论了不同种类的发泡剂对三聚氰胺甲醛树脂发泡理化性能的影响。结果表明,三聚氰胺甲醛树脂"泡孔"是开孔结构,MD I发泡剂能提高树脂的强度,NaH-CO3发泡剂可以提高树脂的阻燃性能,AIBN发泡剂能制备出高发泡材料。     

N,N-bis (2-hydroxyethyl) fatty amide as novel environmentally friendly crosslinking agent for acid functional acrylic copolymer resin

N,N-bis (2-hydroxyethyl) fatty amide (HAFA) derived from dehydrated castor oil (DCO) has been employed as a curing agent for a carboxylic acid functional acrylic resin (AAR). Coating compositions with a varying AAR/HAFA ratio have been prepared and their various film properties have been studied and compared with the conventional butylated melamine formaldehyde (MF) based systems. The study reveals that HAFA can be used successfully as a crosslinking agent for AAR in baking systems. In addition to other technical advantages, the use of HAFA is environmentally friendly as no toxic volatiles are evolved during curing reaction, unlike in MF-cured systems. Department of Industrial Chemistry, Vallabh Vidyanagar, Gujarat 388 120 India. Hyderabad, India.