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.     

UV curable glycidyl carbamate based resins

The synthesis and characterization of UV curable resins based on glycidyl carbamate chemistry have been explored. Glycidyl carbamate (GC) functional resins have been used to obtain crosslinked coatings with a wide range of properties using several crosslinking techniques such as epoxy-amine, self-crosslinking, and sol-gel. GC resin technology was further expanded to UV curable coatings by reacting polyfunctional GC resins with acrylic acid to yield acrylated glycidyl carbamate (AGC) resins. Alcohol-modified UV curable GC resins were also prepared to obtain lower viscosity. Commonly used reactive diluents were used to prepare a UV curable GC coating formulations. The coatings were cured in air using a Fusion LC6B Benchtop Conveyer with an F300 UV lamp. The degree of conversion of acrylic double bonds during UV curing was determined using real time FTIR and showed that the resins had fast cure rates and high extents of conversion of acrylate groups. Coating properties such as hardness, impact strength, methyl ethyl ketone double rubs, flexibility, and adhesion were studied. Dynamic mechanical analysis was used to determine crosslink density of the coatings. Differential scanning calorimetry and thermogravimetric analysis were used to study the thermal properties of the coatings. The type of polyisocyanates and the extent of modification in GC resins influenced the degree of conversion, crosslink density, and coating performance.     

Organic–inorganic hybrid coatings prepared from glycidyl carbamate resins and amino-functional silanes

Organic–inorganic hybrid coatings were prepared from glycidyl carbamate (GC) functional oligomers and different amino-functional trimethoxysilanes via a systematic three-step reaction process. Initially, glycidyl carbamate functional oligomers isocyanurate glycidyl carbamate (IGC) and biuret glycidyl carbamate (BGC) were synthesized from the reaction of the polyisocyanurate of hexamethylene diisocyanate (HDT) with glycidol and the biuret adduct of hexamethylene diisocyanate (HDB) with glycidol, respectively. Then, the GC resins were mixed with 3-aminopropyl trimethoxysilane (APTMES), N-(2-aminoethyl) 3-aminopropyl trimethoxysilane (AEAPTMES) and p-aminocyclohexyl methane (PACM) at different stoichiometric ratios. In order to form the hybrid organic–inorganic networks, the materials were cured either at room temperature and humidity for more than 20 days or with an additional heat treatment at 80 °C for 1 h and then keeping the coatings at room temperature and humidity for more than 10 days. The observable change in the structure during network formation was monitored by FTIR spectroscopy. The cured coatings were characterized by thermogravimetric (TGA) and differential scanning calorimetry (DSC). Atomic force microscopy (AFM) was used to characterize the surface properties of the hybrid systems. AFM observation suggests the phase separation behavior. Coating properties such as König pendulum hardness, crosshatch adhesion, MEK double rub resistance and water contact angle of the coatings were also evaluated. Finally, structure–property relationships are given based on the variable parameters used.     

Novel water-dispersible glycidyl carbamate (GC) resins and waterborne amine-cured coatings

Water-dispersible glycidyl carbamate (GC) functional resins were synthesized and crosslinked using a water-dispersible amine to form coatings. GC functional resins are synthesized by the reaction of an isocyanate functional compound with glycidol to yield a carbamate (urethane) linkage (–NHCO–) and reactive epoxy group. The combination of both functionalities in a single resin structure imparts excellent mechanical and chemical properties to the coatings. Previous studies on the development of GC coatings have focused on solvent-borne coating systems. In this study, GC resins were modified by incorporating nonionic hydrophilic groups to produce water-dispersible resins. To determine the influence of the content of hydrophilic groups on dispersion stability, aqueous dispersions were made from a series of hydrophilically modified GC resins and characterized for particle size and dispersion stability. The composition of a typical, dispersed GC resin particle was predicted using Monte Carlo simulations. Stable GC dispersions were used to prepare amine-cured coatings. The coatings were characterized for solvent resistance, water resistance, hardness, flexibility, adhesion, and surface morphology. It was observed that GC resins were able to be dispersed in water without using any surfactant and by minimal mixing force (hand mixing) and produced coating films with good properties when crosslinked with a compatible waterborne amine crosslinker.     

新型非离子型水性环氧固化剂的合成及性能研究

为提高水性环氧涂料的固化性能和适用期,以自制聚酰胺和生物基戊二胺为起始原料,聚乙二醇二缩水甘油醚（ PEGGE）为亲水链段,双酚 A型环氧树脂（ E-51）为疏水链段,邻甲苯缩水甘油醚（ CGE）为封端剂制备了非离子型低温水性环氧固化剂,并与自制水性环氧乳液复配制得双组分水性环氧涂料。考察了环氧固化剂合成工艺参数及涂膜各项性能。结果表明：该固化剂含有较长的柔性脂肪烃碳链和聚醚链段能够提高涂膜的柔韧性;双酚 A型环氧树脂参与扩链反应能够解决与乳液不兼容等问题;苯环结构增加了涂膜的硬度;涂膜室温固化后性能优异,具有良好的物理机械性能、耐水性、耐酸碱性和耐盐雾性。     

Low VOC carbamate functional coatings compositions for automotive topcoats

Polymers and oligomers having carbamate functional groups have been used in a variety of curable coating compositions. Carbamate functional polymers offer many advantages for automotive topcoats, such as outstanding resistance to environmental etching, scratching and marring, humidity, and UV exposure. Hydrophobic carbamate oligomers suitable for crosslinking with standard amino resins were synthesized and formulated into stable one-pack automotive clearcoats with low volatile organic compound (VOC) and excellent physical properties. Because of their unusually steep thermal viscosity curves, these oligomers are particularly adaptable to hot spray techniques that enable coatings in the 85–90% weight solids range to be applied with conventional electrostatic mini-bells. Presented at the 27th Annual International Waterborne, High-Solids, and Powder Coatings Symposium, in New Orleans, LA, March 2000. Automotive Coatings Technical Center, Southfield, MI 48034.     

Hybrid coatings from novel silane-modified glycidyl carbamate resins and amine crosslinkers

Organic–inorganic hybrid coatings were prepared using silane-modified glycidyl carbamate resins and different amine crosslinkers via the sol–gel process. Two different silane-modified glycidyl carbamate resins with 33% and 20% silane modification were prepared. The synthesized resins were crosslinked with amine crosslinkers such as Amicure PACM, Ancamide 805, Ancamide 2050, Ancamide 2353, Epicure 3164, Jeffamine D-400, etc., at different epoxy to amine equivalent ratios. The formulated hybrid coatings were cured at laboratory temperature and humidity for more than 20 days and subjected to different tests. The hybrid coatings were analyzed using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) during network maturation. Post-cured coatings were also analyzed to understand the effect of structural variables on the coatings thermal properties. Mechanical testing of the post-cured coatings such as König pendulum hardness, crosshatch adhesion and impact resistance were also evaluated. Solvent resistance of the coatings was evaluated by of testing the methyl ethyl ketone (MEK) double rub resistance. Atomic force microscopy (AFM) was used to characterize the surface topography of the hybrid coatings. Finally, structure–property correlations were given based on the observed results.     

Synthesis and applications of cyclic carbonate functional polymers in thermosetting coatings

Thermosetting coatings based on the cyclic carbonate–amine reaction are attractive since polyurethane coatings can be made without the use of isocyanates. Cyclic carbonate functional polymers were prepared via the free radical solution copolymerization of vinyl ethylene carbonate with vinyl ester monomers. The level of vinyl ethylene carbonate was varied from 10 to 50%. In order to develop an understanding of the kinetics of the reaction of cyclic carbonates with amines, kinetics of a number of amines were determined with a model cyclic carbonate, propylene carbonate. The kinetic information was used to help select appropriate amine crosslinkers and develop thermosetting coatings using cyclic carbonate functional polymers and oligomers. For screening of coating properties, clear coating formulations were applied to pretreated metal panels and cured at 80°C for 45 min. A number of coatings were prepared to study the effect of amine, stoichiometry, solvent, and copolymer composition on the coatings properties. Coatings prepared had excellent solvent resistance, good gloss, and high pendulum hardness.     

HAA体系低温固化干混消光粉末涂料用低酸值聚酯树脂的合成及性能研究

通过考察聚酯配方中的二元醇单体的作用，研究酸解剂对涂层性能的影响，并在聚酯中加入特殊搭配的光稳定剂，合成得到了适用于制备羟烷基酰胺（ HAA）体系低温固化干混消光粉末涂料的低酸值聚酯树脂，同时研究了粉末涂料的固化反应。结果表明：该粉末涂料具有较低的活化能，制备涂层可以实现 160 ℃低温固化，消光光泽约为 28，涂层具有良好的耐冲击性和耐老化性能，综合性能优异。     

Imidazole catalysis in the curing of epoxy resins

The high catalytic activity of imidazoles and particularly of 2-ethyl-4-methylimidazole (EMI) for the curing of epoxy resins and the properties of the resulting resins prompted this study concerned with the nature of the curing reaction. Epon 828 epoxy resin and the model compound phenyl glycidyl ether were used as starting materials with EMI, 2-methylimidazole, and dimethylbenzylamine as catalysts. During the curing of the resin at 50°C., the decrease in the infrared absorption of the epoxy band with time is accompanied by a decrease in the intensity of the imine band of the imidazole moiety, indicating its reaction with the epoxy group and its incorporation into the resin. The measurement of the residual epoxy content after curing for 24 hr. at 50 and 140°C. showed that the imidazoles were not more efficient in completing the epoxy reaction than dimethylbenzylamine. In the experiments with phenyl glycidyl ether the rate of reaction of the epoxy group with EMI was faster than the rate of polymerization, proving that the imidazole becomes permanently attached to the polymer chain. These results also suggest that the true catalytic species is not EMI but some addition product thereof. In comparative rate measurements the compound formed from equimolar quantities of EMI and phenyl glycidyl ether was found to be an excellent catalyst. The NMR analysis of the 1:1 and 1:2 adducts of EMI and phenyl glycidyl ether has shown that the second mole of phenyl glycidyl ether reacts with the ring nitrogen in the 3 position and not with the hydroxyl group of the mono adduct. By forming the bis adduct in this way the imidazole molecule acts as a crosslinking agent and at the same time introduces an alkoxide ion which can initiate further polymerization. It is very likely that this crosslinking is the process that leads to the superior physical and chemical properties (high heat deflection temperature, resistance to chemicals and oxidation) of the resins prepared with imidazoles as catalysts.     

A new curing system for automotive topcoat

In response to the need for an acid rain resistant topcoat, a curing system was prepared using two kinds of acrylic polymers; one contains a half-ester of acid anhydride and the other both a hydroxyl and glycidyl group as the functional groups. The half-ester group polymer does not react with a hydroxyl group at room temperature, but releases alcohol and reproduces an acid anhydride at elevated temperatures, and subsequently rapid polymer–polymer reaction through acid anhydride and hydroxyl group occurs. Carboxyl group produced during this crosslinking reaction reacts with glycidyl group. This reaction made it possible to design a one component curing system with a higher crosslink density. Upon adapting the curing system for automotive clearcoat, a function of mar resistance was also necessary, which was achieved by using hydroxyl monomer containing longer alkylene group.     

Thermal cationic curing with benzylammonium salts

Novel cationic initiators, benzylanilinium salts, were synthesized from benzylchloride and N,N-dimethylaniline followed by exchange of counter anion with SbF₆⁻. Benzylanilinium salts showed thermal latency as initiator in the cationic polymerization of glycidyl phenyl ether. The electrophilic characteristic of the benzyl group of benzylanilinium salts were estimated by the reaction of D₂O using ¹H NMR. The electrophilic characteristics of the benzyl group in benzylanilinium salts depended on the p-substituents (benzyl position in benzylanilinium salts). Cationic curing systems, consisting of benzylanilinium salts and the polymer containing oxirane moieties, were proposed and some properties of films obtained by this systems were evaluated. It was found that cationic curing systems had some better properties, especially resistance to acid, than those of the melamine curing systems and that anilinium salts were more useful than benzylpyridinium salts as the initiators for cationic curing systems for coatings.     

Inorganic/organic nanocomposite coatings: The next step in coating performance

Inorganic/organic hybrid materials have considerable promise and are beginning to become a major area of research for many coating usages, including abrasion and corrosion resistance. Our primary approach is to prepare the inorganic phase in situ within the film formation process of the organic phase. The inorganic phase is introduced via sol-gel chemistry into a thermosetting organic phase. By this method, the size, periodicity, spatial positioning, and density of the inorganic phase can be controlled. An important aspect of the inorganic/organic hybrid materials is the coupling agent. The initial task of the coupling agent is to provide uniform mixing of the oligomeric organic phase with the sol-gel precursors, which are otherwise immiscible. UV-curable inorganic/organic hybrid systems have the advantages of a rapid cure and the ability to be used on heat sensitive substrates such as molded plastics. Also, it is possible to have better control of the growth of the inorganic phase using UV curing. It is our ultimate goal to completely separate the curing of inorganic and organic phases to gain complete control over the morphology, and hence optimization of “all” the coating properties. Thus far, it has been found that concomitant UV curing of the inorganic and organic phases using titanium sol-gel precursors afforded nanocomposite coatings which completely block the substrate from UV light while maintaining a transparent to visible light. Also, it has been found that the morphology of the inorganic phase is highly dependent on the concentration and reactivity of the coupling agent. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004, in Chicago, IL.     

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℃。     

Linear glycidyl carbamate (GC) resins for highly flexible coatings

An approach to the design of highly flexible coatings based on glycidyl carbamate (GC) chemistry is presented. In past work, GC resins had been synthesized by reacting polyisocyanates such as hexamethylene diisocyanate biuret or hexamethylene diisocyanate isocyanurate resins with glycidol. When crosslinked with amines, due to their high functionality, these resins form very hard and tough coatings, but the coatings have limited flexibility. To obtain coatings with good flexibility, several GC resins were synthesized using linear and cycloaliphatic diisocyanates and a combination of diols and triol with glycidol. The combination of linear diisocyanates and diols introduces a more linear structure in the GC resin compositions. Crosslinked coatings were obtained using two amine crosslinkers, para-aminocyclohexyl methane (PACM) and a commercial polyamide, Ancamide-2353 (A-2353). The flexibility of the coatings was characterized using reverse impact test, GE impact test, and elongation at break in tensile test. The coatings were further characterized to determine their chemical resistance, hardness, thermal stability, and corrosion resistance. The diisocyanate composition and composition of diols and triol influenced the performance of the coatings. In order to understand the influence of the composition of the GC resins on their performance, coatings were characterized using differential scanning calorimetry and dynamic mechanical analysis.     

A new class of silicone resins for coatings

A new class of silicone has been developed for coatings or as coating additives. Cycloaliphatic silane monomers were prepared and reacted into more easily handled cyclic oligomers. These cyclic oligomers were ring-opened into siloxane polymers. The polymers were functionalized with a variety of groups, including: amino, glycidyl epoxide, cyclohexene epoxide, acrylic, and alkoxysilane. The cycloaliphatic silicones have been designed for a number of different curing conditions: (1) ambient temperature-cure (amino and glycidyl epoxide), (2) cationic ultraviolet (UV)-cure (cyclohexene epoxide), (3) radical UV-cure (acrylic), and (4) moisture-cure (alkoxysilane). The end usages thus far have been focused on silicone coatings; however, usage as coating additives will be a focus for future research. The cycloaliphatic silicone has been UV-cured with mixed sol–gel precursors for usage as aerospace coatings. The cycloaliphatic silicones have also been ambient temperature-cured for release coatings, and have application as anti-fouling coatings. The inherent low surface energy makes the cycloaliphatic silicones prime candidates for surface tension additives. Presented at the 2006 FutureCoat! Conference, sponsored by the Federation of Societies for Coatings Technology, in New Orleans, LA, on November 1–3, 2006.     

Catalysis of the epoxy-carboxyl reaction

We have investigated the reactions of glycidyl ether, glycidyl ester, and other oxirane functional resins with carboxyl or anhydride functional compounds and polymers in the presence of a wide range of amine, phosphonium, and metal catalysts. We confirmed that both amine and phosphonium compounds can catalyze the reaction of epoxy groups with carboxyl and anhydride groups. There are certain deficiencies with these catalysts, such as a tendency to yellow and a reduction in stability at ambient or elevated temperatures. We also observed that many of the known amine catalysts contribute to poorer humidity resistance and exterior durability. Several metal salts were found to be effective catalysts, but they also contributed to a reduction in chemical resistance or they led to paint instability. We have discovered a group of metal chelates that overcome these problems and provide stable formulations in a single package that do not yellow during cure and that give improved resistance properties. The new catalysts have been evaluated in high-solids epoxy/carboxyl coatings, automotive clearcoats, and powder coatings. Presented at the International Waterborne, High-Solids and Powder Coatings Symposium, February 21–23, 2001, New Orleans, LA. Science Rd, Norwalk, CT 06852.     

高质量羟基丙烯酸树脂的合成及应用研究

介绍了改性高质量羟基丙烯酸树脂的合成工艺,讨论了引发剂、链转移剂、反应温度及叔碳酸缩水甘油酯等因素及所合成的新型羟基丙烯酸树脂与六甲氧基甲基三聚氰胺树脂(HMMM)的交联型丙烯酸汽车罩光清漆的性能,该涂料具有优良的耐酸性,较高的施工固体份及出色的物理力学性能。     

星形齐聚物在光固化涂料中的应用

对由阴离子聚合法、有机合成法、缩合聚合法合成的可辐射固化的星形齐聚物，用高效液相色谱仪进行了测试，比较了星形齐聚物与相应的线性齐聚物的粘度、固化速度情况，对由星形齐聚物所配制的紫外光固化涂料的理化性能进行了分析测试，结果表明，该涂料粘度低，固化速度侠，其漆膜具有优异的理化性能。