Epoxy ester-type resins from

Epoxy ester-type resins from diepoxide... 

Synthesis. The synthesis of epoxy ester type resins from diepoxide ( ) is illustrated in Figure 1. 

Resins. The epoxy ester was prepared from one of the solid grades of epichlorohydrin/bisphenol-A type resin. The resin was first esterified with benzoic acid to 40% of the available esterifiable groups. The re-... 

Epoxide resins can be esterified with fatty acids to give media ranging from air-drying to stoving types. The presence of fatty acid reduces the chemical resistance to the same order as that of the alkyds. It is nevertheless sometimes found advantageous to use an epoxy ester for certain specialised purposes. 

A plastisol may be regarded as an organosol in which the continuous phase is almost entirely liquid plasticizer (small amounts of solvent are used for viscosity adjustment). PVC plastisols are made from PVC powder, adipate and phthalate ester plasticizers and minor amounts of epoxy-type resin in solution to aid pigment dispersion and to help (with other additives) to keep the polymer stable to heat and oxidation. The resultant coating is nearly solvent-free and so can be applied in thick films (100-250 m) and stoved without disruption by escaping solvent. The plasticizer penetrates the particles, aiding sintering as the metal substrate reaches c. 200°C in 30-60 s. 

Two resin types were investigated, including epoxy esters from stepwise reaction of sucrose-partial drying oil ester with cyclic anhydride and diepoxide, and polyurethanes from sucrose-partial drying oil ester and diisocyanate. Details of synthesis of the resins and their evaluation as coatings are discussed below. 

Epoxy resin esters are formed from reacting an epoxy resin with fatty acids from drying oils in the same type of equipment used to make alkyds. The fatty acids react with both the epoxide and hydroxyl groups of the epoxy resin to form the epoxy ester, as in Figure 17. 

The coatings were cured in two steps first, a room temperature exposure for at least five hours to allow any solvent present to evaporate and/or the resin to gel and, second, an elevated temperature cure. The vinyl ester, polyester and epoxies were baked at 60°C for 4-16 hours. The coating thickness after curing was measured with a micrometer, subtracting the substrate thickness. The thickness of the coatings ranged from 6 to 12 mils (150-300 urn) and is shown for each type in Table I. 

Units of this type are available from a number of sources, usually manufactured from a polyester or vinyl ester resin, although a few epoxy structures are also on the market. At least one vendor is casting such units to order from a fu-ran castable. The standard, off-the-shelf items rarely have a top circumferential flange-a necessity if they are to be mated with an adjacent membrane system, as shown in the drawing cited above, and the buyer should make the provision of such a flange a condition of purchase. 

Within the different types of epoxies, are found epoxy diacrylates or vinyl ester resins, used to produce specific corrosion and chemical resistant composite systems. Vinyl ester resins are produced by either reacting epoxy resins of glycidyl derivatives with methacrylic acid, or from BPA and glycidyl methacrylates, where an active monomer (usually styrene) as crosslinker, hardener (usually organic peroxides), accelerators (cobalt) are added to the system. In the thermoset epoxy systems, there are also the mould releasers , which can be either internal such as, lecithin, or stearates of zinc and calcium, certain organic phosphates that are mixed in the resin, or, external - such as, fluorocarbons, silicone oil, and certain waxes, that are directly laid on the mould. 

In another study, three types of composite materials were obtained from (i) blends of soybean oil-based epoxy with commercial petroleum-based epoxy resin and E-glass fibre, (ii) blends of epoxidised methyl ester derived from canola oil with petroleum-based epoxy resin and E-glass fibre, and (iii) 100% petroleum-based epoxy resin and E-glass fibre. Panels made as in (i) exhibited comparable dynamic stiffness, flexural modulus and flexural stiffness properties to those derived from composite system (iii) However, bio-based samples from process (ii) were less promising. 

Carboxylic nitrile liquid and solid elastomers are used to prepare elastomer-modified epoxy liquid and solid resins when it is desirable to have the modifier in the epoxy portion of the system. This is effected through alkyl-hydroxy esterification reactions. This is covered in the literature for uncatalyzed liquid resins (9), for tert-amine catalyzed systems (10), for tert-phosphine catalyzed systems (11), for low molecular weight solid resins advanced from the liquid state (12) and for liquid and solid resins where an additional rubber vulcanization step is carried out in addition to the alkylhydroxy ester adducting step (13). Such adduct preparations offer formulation stability with a wide range of hardener types amines, anhydrides, catalytic, Lewis acids/bases. 

The global thermoset resins market is expected to reach as high as 95 million metric tons by 2016 (Axis Research Mind report 2012). Excluding the alkyd resins, which are used primarily in the coatings, commercially important major types of thermoset resins, altuig with their relative % market share, estimated from literature (Fosdyke and Starr 2002), can be categorized as follows Polyurethanes (31 %), PhenoUcs (18 %), Amino resins (18 %), Unsaturated polyesters (12 %), Epoxies and other specialty/high performance thermosets (12 %), such as silicones, polyimides, bismaleimides (BMl), cyanate ester thermosets, etc. 

Liquid crystals exhibit a partially ordered state (anisotropic) which falls in-between the completely ordered solid state and completely disordered liquid state. It is sometimes referred to as the fourth state of matter . In recent years, interest in liquid crystalline thermosets (especially liquid crystalline epoxy) has increased tremendously [33-44]. If the liquid crystal epoxy is cured in the mesophase, the liquid crystalline superstructure is fixed permanently in the polymer network, even at higher temperature. Liquid crystal epoxies are prepared using a liquid crystal monomer [33-38] or by chemical modification of epoxy resin [43] which incorporates liquid crystal unit in the epoxy structure. Liquid crystalline epoxy resins with different types of mesogen such as benzaldehyde azine [33], binaphthyl ether [34, 35], phenyl ester [36, 37] and azomethine ethers [38, 39] have been reported. Depending on the chemical nature of the mesogen, the related epoxies display a wide range of thermomechanical properties. The resins can be cured chemically with an acid or amine [40, 41] or by photochemical curing in the presence of a photo-initiator [3]. Broer and co-workers [42] demonstrated the fabrication of uniaxially oriented nematic networks from a diepoxy monomer in the presence of a photo-initiator. 

Similarities to epoxy resin include no volatile polymerization byproducts stable B-stage resins possible low shrinkage, high adhesion and void free structures. High purity makes cyanate esters very attractive for use in electronic applications. The performance of bisphenol A dicyanate resins in printed wiring board laminates was described by Weirauch et al(4). Mobay Chemical (and Bayer) introduced products of this type for PWB applications in the United States in 1976-78. These "Triazine A resins were not commercially successful and were withdrawn from the market about 1979. 

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