Study on esterification of acrylic phenolic resin by maleic anhydride and photocrosslinking properties of the alkali‐soluble product

An alkali‐soluble, photocrosslinkable polymer was synthesized by esterification of OH groups of acrylic phenolic resin with maleic anhydride. The OH groups were formed by the ring‐opening reaction of epoxy groups of epoxy phenolic resin with acrylic acid. The esterification conditions were studied. The results showed that it is better to use tetramethyl ammonium bromide as catalyst than N,N‐dimethylbenzylamine. The conversion of maleic anhydride in acetone can reach about 80% at 56°C for 4 h. The purified product was characterized by IR, DSC, and TGA. The product containing acrylate and maleic acid monoester groups, above a certain content, can be dissolved in 1% Na₂CO₃ solution. The photocrosslinkable properties of the product were investigated through selection of photoinitiator, accelarator, crosslinkable diluent monomer, etc. The acrylate and maleic acid monoester group‐containing phenolic resin exhibited very good photocrosslinking behavior, since it contains double bonds from both acrylate groups and maleic acid monoester groups. The activity of photoinitiator decreases in the order: isopropylthioanthraquinone > benzoin ethyl ether (BE) > anthraquinone (AQ) > benzophenone > Michel ketone (MK) > 2,2‐diethoxyacetophenone. The combination of some photoinitiators showed synergistic effects. The order of increasing activity for the accelerator is as follows: MK > ethyl p‐(dimethylamino)benzoate > N,N‐dimethylaniline > triethanolamine. The optimum diluent monomer is trimethylolpropane trimethacrylate. The gel content of the mixture of the resin and trimethylolpropane trimethacrylate could reach 85% using the combined photoinitiators of BE and AQ under UV exposure for 120 s. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1607–1614, 2005     

Hybridization of aqueous PU/epoxy resin via a dual self‐curing process

Amino‐terminated and carboxyl‐containing polyurethane (PU) is prepared by an isocyanate‐terminated PU prepolymer process. Carboxyl‐containing epoxy resin is obtained from a half‐esterification of epoxy resin with maleic anhydride. These two aqueous resins are obtained after neutralization with triethylamine and dispersion into water phase, respectively. A latent curing agent (TMPTA‐AZ) is prepared by a Michael addition of aziridine with trimethylolpropane triacrylate (TMPTA). A self‐curing system of PU/epoxy hybrid is obtained from a blending of these two aqueous resins with latent curing agent. PU/epoxy hybrid is derived from two self‐curing reactions on drying. The first curing for hybridization between PU amino groups with oxirane groups of epoxy resin is via a ring‐opening reaction and the secondary curing takes place on carboxyl groups of PU/epoxy hybrid with aziridine of TMPTA‐AZ. The final properties of these dual self‐cured PU/epoxy hybrids are reported. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Selection of quaternary ammonium groups for optimizing properties of water‐soluble,photosensitive phenolic resins and study of their postcuring mechanism

This article deals with the selection of quaternary ammonium groups for synthesis of water‐soluble, photosensitive phenolic resins, containing acrylate and different quaternary ammonium salt groups (AQSPRs), via ring‐opening reactions of epoxy phenolic resin (EPR) with acrylic acid and with different tertiary amine‐protonic acid salts. Conversion of epoxy groups, solubility, photosensitive properties, and thermal decomposition of the different AQSPRs were compared. Modification of AQSPR with methanol solution of KOH to form phenolic resin containing both quaternary ammonium hydroxide groups and acrylate groups (AQHPR) was also studied. Characterization by IR spectrum, DSC, and thermal gravimetric analysis was carried out. The results showed that in the synthesis of AQSPRs containing different quaternary ammonium salt groups, the efficiency of ring‐opening reaction of epoxy phenolic resin with tertiary amine salt in terms of conversion of epoxy groups decreases in the following order: for the tertiary amine, N,N‐dimethyl benzylamine (DMBA) > triethylamine (TEA) > trimethylamine (TMA) > N,N‐dimethyl aniline (DMA) > triethanolamine (TENA) > tri(n‐butylamine) (TBA); for the protonic acid, HCl > HBr > HCOOH > HI > NaHSO₃ > Cl₃CCOOH > HClO₄ > HBF₄. All the AQSPRs except that from HClO₄ can be dissolved in water, methanol, DMF, or DMSO. The gel content formed during UV exposure decreases in the following order of acids used in forming quaternary ammonium salt groups: HCl > HCOOH > NaHSO₃ > Cl₃CCOOH; or decreases in the following order of tertiary amines or hydrohalic acids used in forming the quaternary ammonium groups: TMA. > TEA > DBMA; HCl > HBr > HI. During thermal decomposition of EPR with about half epoxy groups of EPR ring‐opened with tertiary amine salt at 160°C for 0.5 h, water‐insoluble product was formed. The insoluble content and the % decrease of epoxy groups or halide ions increase in the following order: TMA < TEA < DMBA; HCl < HBr < HI. The % decrease of epoxy groups for the insoluble residue is nearly equal to the % decrease of halide ions. A crosslinking reaction mechanism occurred in the thermal decomposition was thus proposed. During the modification of AQSPR with KOH, conversion of quaternary ammonium chloride groups can reach above 90%. The decomposition temperature of the quaternary ammonium groups was lowered from 204 to 120°C after modification of AQSPR with KOH. The photosensitive properties of the resin after modification became lower. It is better to react DMBA · HCl with EPR so as to obtain a product with higher conversion of epoxy groups, good water solubility, moderate photosensitivity, lower decomposition temperature, and better postcuring. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2914–2922, 2004     

Synthesis of sulfonated rubber ionomers by the ring‐opening reaction of epoxidized styrene–butadiene rubber,their characterization,and their properties

A novel method for the synthesis of the sulfonate ionomer of styrene‐co‐butadiene rubber (SBR) was developed. SBR was first epoxidized by performic acid formed from hydrogen peroxide and formic acid in situ in solution, and this was followed by a ring‐opening reaction with an aqueous solution of NaHSO₃. The optimum conditions for the epoxidation of SBR in the presence of a phase‐transfer catalyst and for the ring‐opening reaction of epoxidized SBR with an aqueous solution of NaHSO₃ were studied. During the epoxidation of SBR, a phase‐transfer catalyst, such as poly(ethylene glycol), could enhance the conversion of double bonds to epoxy groups. During the ring‐opening reaction, both the phase‐transfer catalyst and ring‐opening catalyst were necessary to enhance the conversion of the epoxy groups to ionic groups. The addition of Na₂SO₃ to the reaction mixture was important to obtain 100% conversion. The products were characterized with Fourier transform infrared spectrophotometry, ¹H‐NMR spectroscopy, differential scanning calorimetry (DSC), and transmission electron microscopy (TEM). DSC showed that the sodium sulfonate SBR ionomer possessed a dissociation temperature of ionic domains at 110°C, which appeared as black spots under TEM, after the sodium ions of the ionomer were substituted by lead ions. Some properties of the sodium ionomer, such as the water absorbency, oil absorbency, and dilute solution behavior, were studied. With increasing ionic groups, the water absorbency of the ionomer increased, whereas the oil absorbency decreased. The dilute solution viscosity of the ionomer increased abruptly with increasing ionic group content. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3090–3096, 2006     

Polymerization of an epoxy resin modified with azobenzene groups monitored by near‐infrared spectroscopy

New photosensitive materials containing photochromic azobenzene moieties were synthesized. For this purpose, an epoxy resin based on diglycidyl ether of bisphenol A (DGEBA) was reacted with an azobenzene chromophore (disperse orange 3, AZ) to satisfactorily synthesize an azo‐modified prepolymer, which was then used to generate series of epoxy‐based polymers containing azo groups. Three different amines were used as hardeners, with the aim of obtaining materials with different chemical structures. Understanding the epoxy resin polymerization kinetics is essential for intelligent processing of materials. Near‐IR (NIR) spectral analysis was used to follow the polymerization kinetics. The quality of the NIR spectra enables concentrations of individual chemical species to be measured in real time. Conversion of epoxy and primary amine groups, as well as the concentration of different groups, as a function of reaction time was therefore calculated by this spectroscopic technique. Samples containing azo units were compared to the pure DGEBA/amine systems. Results showed that the azo‐prepolymer incorporation has an accelerating effect on polymerization rate. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Interphase Reaction of Isocyanates with Epoxy Resins Containing Functional Groups of Different Reactivity

Interphase reactions between cured epoxy resins and isocyanates are investigated. The epoxy resins contain secondary hydroxyl groups as reactive groups only or secondary hydroxyl plus amine. The isocyanate diffuses into the epoxy resin forming an interphase with a thickness of some micrometers. Depending on the functional groups available in the epoxy resin, urethane and urea groups are formed in the interphase. If a monofunctional isocyanate is used, no difference between both kinds of epoxy resin could be detected regarding the formation of urethane. If the epoxy resins react with bifunctional isocyanates a crosslinked interphase is formed. Due to the higher reactivity between amine and isocyanate compared to hydroxyl and isocyanate, the urea is formed first. The resulting cross‐links restrict the further diffusion of isocyanate into the epoxy resin. The consequence is a lower urethane content in the interphase and a thinner interphase compared to the epoxy resin containing hydroxyl only. If a prepolymer with isocyanate end groups is used as isocyanate the formation of the interphase is slower compared to the low molecular weight isocyanate. This is due to the reduced mobility of the prepolymer.     

积层电路板制造用光敏预聚物的合成及应用研究

用丙烯酸对酚醛环氧树脂进行改性,以使其具有感光性。考察温度及催化剂用量对反应的影响,并介绍积层电路板制造用液态感光成像油墨的配方和制作工艺,分析以合成的光敏预聚物为主体配制的油墨的感光性。结果发现,合适的反应温度为90℃,反应5h,转化率达91.83%;以十六烷基三甲基溴化铵为催化剂,其质量分数以1.5%为宜;以自制的光敏预聚物配制的油墨,在曝光20s时,双键的转化率可达80%以上。     

Synthesis and properties of novel amphiphilic sulfated ionomers by the ring‐opening reaction of an epoxidized styrene–butadiene–styrene triblock copolymer

A method for the synthesis of novel sulfated ionomer of styrene–butadiene–styrene triblock copolymer (SBS) was developed. SBS was first epoxidized by performic acid in the presence of a phase‐transfer catalyst; this was followed by a ring‐opening reaction with an aqueous solution of alkali salt of bisulfate. The optimum conditions for the ring‐opening reaction of the epoxidized SBS with an aqueous solution of KHSO₄ were studied. During the ring‐opening reaction, both phase‐transfer catalyst and ring‐opening catalyst were necessary to enhance the conversion of epoxy groups to ionic groups. The products were characterized with Fourier transform infrared spectrophotometry and transmission electron microscopy (TEM). After the potassium ions of the ionomer were substituted with lead ions, the lead sulfated ionomer exhibited dark spots under TEM. Some properties of the sulfated ionomer were studied. With increasing ionic groups or ionic potential of the cations, the water absorbency and emulsifying volume of the ionomer and the intrinsic viscosity of the ionomer solution increased, whereas the oil absorbency decreased. The sulfated ionomer possessed excellent emulsifying properties compared with the sulfonated SBS ionomer. The sodium sulfated ionomers in the presence of 10% zinc stearate showed better mechanical properties than the original SBS. When the ionomer was blended with crystalline polypropylene, a synergistic effect occurred with respect to the tensile strength. The ionomer behaved as a compatibilizer for blending equal amounts of SBS and oil‐resistant chlorohydrin rubber. In the presence of 3% ionomer, the blend exhibited much better mechanical properties and solvent resistance than the blend without the ionomer. SEM photographs indicated improved compatibility between the two components of the blend in the presence of the ionomer. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Viscoelasticity of epoxy resin/silica hybrid materials with an acid anhydride curing agent

The viscoelasticity of epoxy resin/silica hybrid materials manufactured by the sol–gel process with an acid anhydride curing agent was investigated in terms of morphology. Transmission microscopy observations demonstrated that all the prepared hybrid samples had a two‐phased structure consisting of an epoxy phase and a silica phase. The formed silica had either nanosized particles or coarse domains, depending on the catalyst for the sol–gel process. Raman spectroscopy analysis showed that the formed silica had features typical of sol–gel derived silica glass and that the ring‐opening reactions of the epoxy groups developed in the hybrid samples and in the neat epoxy samples. In dynamic mechanical thermal analysis, there were two transition temperatures due to epoxy chain mobility and epoxy network relaxation, through which the moduli changed by nearly 3 orders of magnitude. The hybridization disturbed epoxy network formation but also reinforced the epoxy network with the formed silica, which was characterized by the activation energy of the network relaxation; therefore, the modulus of the rubbery state was correlated to the activation energy. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis of epoxy resins from alcohol‐liquefied wood and the mechanical properties of the cured resins

New wood‐based epoxy resins were synthesized from alcohol‐liquefied wood. Wood was first liquefied by the reaction with polyethylene glycol and glycerin. The alcohol‐liquefied wood with plenty of hydroxyl groups were precursors for synthesizing the wood‐based epoxy resins. Namely, the alcoholic OH groups of the liquefied wood reacted with epichlorohydrin under alkali condition with a phase transfer catalyst, so that the epoxy groups were put in the liquefied wood. The wood‐based epoxy resins and the alcohol‐based epoxy resins as reference materials were cured with polyamide amine. The glass transition temperature (Tg), the tensile strength, and the modulus of elasticity of the wood‐based epoxy resin were higher than those of the alcohol‐based epoxy resin. Also, the shear adhesive strength of the wood‐based epoxy resin to steel plates was higher than those of the alcohol‐based epoxy resins, which was equivalent to the level of petroleum‐based bisphenol‐A type epoxy resins. The higher Tg of the wood‐based epoxy resin than that of the alcohol‐based epoxy resin is one of the evidences that the wood‐derived molecules were chemically incorporated into the network structures. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Effects of variation in composition and temperature on the amine cure of an epoxy resin model system

Prior liquid chromatographic studies have shown that the reactions in epoxy resin model system phenyl glycidyl ether, p-chloroaniline, and Monuron include amine addition to epoxy, homopolymerization of the epoxy, and a chain-transfer reaction involving the hydroxy groups of the addition products. The present work examines the effect of variation in concentration of the accelerator Monuron, the amine-to-epoxy ratio, and the temperature on the competitive reaction mechanisms. The fraction of phenyl glycidyl ether reacting by homopolymerization increases with accelerator concentration and decreases with increasing amine-to-epoxy ratio and increasing temperature. The estimated contribution from chain transfer is much smaller and appears to parallel the homopolymerization reaction, as might be expected.     

The role of impurities in the mechanisms and kinetics of reactions of epoxy resins and their effects on final resin properties

A series of commercial tetrafunctional epoxy prepolymers were step-growth polymerised with aromatic amines. The roles of non-epoxy chain ends and of impurities in the polymer were shown in terms of the mechanisms, reaction kinetics and final thermal properties of the material. The pure prepolymer was studied after preparative chromatographic separation. In the temperature range 100–180°C, epoxy-primary amine reactions predominate at the beginning, followed by epoxy-hydroxyl and epoxy-secondary amine reactions at the end of the reaction sequence. These reactions may be either intermolecular forming cross-linked networks, or intramolecular forming rings, the latter occurring primarily at the end of heat treatment. At temperatures higher than 180°C, there are breakdown reactions and homopolymerisation of epoxy groups. Based on data obtained with ¹³C solid phase cross polarization magic angle spinning nuclear magnetic resonance, inverse phase gas chromatography and Calvet microcalorimetry, the progress of the reaction could be determined up to the gel point and in the vitrification zone. Based on structural results (assays of residual functions and those formed in the cross-linked networks), it was possible to establish relationships between structures and thermal properties.     

电泳涂料用硫鎓盐、季铵盐混合型分散树脂的合成与性能研究

以硫醚化合物和叔胺类化合物共同与环氧树脂反应制备一种新型硫鎓盐分散树脂,以提高电泳涂层的外观和耐腐蚀能力.通过质子化硫醚和质子化叔胺混合开环环氧树脂,并在树脂中引入柔韧链段,制备一种颜填料分散树脂.对比了分别由混合型分散树脂和季铵盐树脂制备的涂层耐盐雾性能、机械力学性能和贮存稳定性.结果表明:在使用铁系磷化作为前处理时...     

柔性环氧丙烯酸酯光固化树脂的研究

通过对环氧树脂进行改性,增加其韧性,再用丙烯酸酯化,制得柔性环氧丙烯酸酯预聚体.研究了反应原料的摩尔比、反应温度、催化剂类型及用量对反应及产物性能的影响,确定了环氧树脂改性反应和丙烯酸酯化反应的最佳条件,研究了树脂的固化性能.     

Kinetics of in situ epoxidation of soybean oil in bulk catalyzed by ion exchange resin

The kinetics of the epoxidation of soybean oil in bulk by peracetic acid formed in situ, in the presence of an ion exchange resin as the catalyst, was studied. The proposed kinetic model takes into consideration two side reactions of the epoxy ring opening involving the formation of hydroxy acetate and hydroxyl groups as well as the reactions of the formation of the peracid and epoxy groups. The catalytic reaction of the peracetic acid formation was characterized by adsorption of only acetic acid and peracetic acid on the active catalyst sites, and irreversible surface reaction was the overall rate-determining step. Kinetic parameters were estimated by fitting experimental data using the Marquardt method. Good agreement between the calculated and experimental data indicated that the proposed kinetic model was correct. The effect of different reaction variables on epoxidation was also discussed. The conditions for obtaining optimal epoxide yield (91% conversion, 5.99% epoxide content in product) were found to be: 0.5 mole of glacial acetic acid and 1.1 mole of hydrogen peroxide (30% aqueous solution) per mole of ethylenic unsaturation, in the presence of 5 wt% of the ion exchange resin at 75°C, over the reaction period of 8 h.     

A new epoxy/episulfide resin system for electronic applications — 2: pot life and prepreg storage life evaluation

A new epoxy/episulfide thermosetting resin was evaluated, using a dicyandiamide (DICY) curing agent. The system was found to exhibit a longer pot life and prepreg storage life than the standard epoxy system. The properties are attributable to the change in reaction mechanism caused by the addition of episulfide. The reaction mechanisms were studied using a mono-functional model compound system; the extent of episulfide-amine reaction is relatively high in the epoxy/episulfide system relative to epoxy-amine. A tert-amine salt is probably formed which does not act as a catalyst for the epoxy ring opening, resulting in a greater pot life.     

Preparation and characterization of cardanol‐based epoxy resin for coating at room temperature curing

Novel organic solvent‐free bio‐based epoxy resin for coating was prepared from cashew nut shell liquid which is one of renewable resources. The epoxy coating was fabricated by the reaction between amine compounds and epoxy cardanol prepolymer (ECP). The drying, physical, and thermal properties of the epoxy were investigated and compared with those of the commercial cashew coating. The ECP was synthesized by thermal polymerization under the various conditions. Based on the FT‐IR analysis, hydroxyl and carbonyl groups were generated, and viscosity increased with increasing heating temperature and time. On the other hand, the NMR analysis showed decrease in the degree of unsaturation in the side group of cardanol. Based on these results, the polymerization of the ECP could be autoxidized in the unsaturated group in the side chains. The drying time until harden dry of the ECP coating took about 2.5 h at room temperature, which is faster than that of the commercial cashew coating. This is because that the curing of ECP coating was based on the prepolymer (i.e., high molecular weight) and crosslink reaction between epoxy and amine groups. The ECP coating was rubbery state due to the flexible side chains of cardanol. Furthermore, the ECP coating improved chemical stability compared with the commercial cashew. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2468–2478, 2013     

Development of bio-based hybrid resin,from natural lacquer

Preparation and structure analysis of a bio-based hybrid material composed of natural lacquer, epoxy, and organic silane compounds were investigated using liquid and solid-state nuclear magnetic resonance. The good composition of additives in the hybrid was determined by the drying, hardness, and resin-molding properties. Although natural lacquer alone cannot form thick resins, this bio-based hybrid material showed good resin formation at room temperature without thermal treatment. This result could be based on the enhancement of curing by the sol–gel reaction between natural lacquer and the organic silane compound, and a crosslink reaction between organic silane and epoxy groups. At the same time, oxidative polymerization at the unsaturated side chains in the urushiol was enhanced by the sol–gel reaction because the catechol hydroxyl groups, which have an antioxidative property, reacted with the organic silane. In addition, this bio-based resin possesses a thermoset property because curing of the hybrid was improved by thermal treatment. Based on the structure analyses, the sol–gel reaction between urushiol and organic silane compound proceeded immediately, indicating the high reactivity of this sol–gel reaction. On the other hand, the reaction between bisphenol A-type epoxy resin and the organic silane seems to progress slowly after the epoxy ring opening. In addition, a sol–gel reaction occurred between the amine group in the organic silane and the hydroxyl group formed after the crosslink reaction of the epoxy group. These results suggested that the improvement in drying and molding properties of the hybrid was based on the chemical reactions among all components (i.e., natural lacquer, epoxy, and organic silane).     

环氧树脂用KH550开环改性水性聚氨酯涂料的合成及性能研究

由于环氧树脂中环氧基团的存在,在合成环氧树脂改性水性聚氨酯预聚体和后扩链过程中,会消耗部分—NCO、胺类扩链剂,对整个合成的配方设计造成影响,重现性也差。通过KH550中的伯胺先打开环氧基团,然后改性的水性聚氨酯作为大分子扩链剂接到水性聚氨酯预聚体中,成功制备了稳定的水性聚氨酯乳液。通过傅里叶变换红外光谱和接触角测量仪对树脂的结构进行了表征。研究结果表明:KH550成功打开了环氧基团,并且树脂接上了有机硅类功能性材料,使得合成的树脂接触角大大提高。     

环氧树脂化学改性有机硅树脂的方法综述

环氧改性有机硅树脂可提高有机硅树脂的力学性能和粘接性能,还可降低有机硅树脂的固化温度.归纳总结了环氧树脂化学改性有机硅树脂的4种反应类型:1)缩聚反应;2)环氧基的开环聚合反应;3)硅氢加成反应;4)引入环氧基的反应.对该领域的近期研究成果进行了简要的综述,并展望了该领域未来的发展方向.