Epichlorhydrin, properties

Aftertreatments include resin finishes, which improve fastness properties, and dye-fixing agents of the epichlorhydrin—organic amine type. These agents react with the dye to give condensation products that are not water soluble and hence more difficult to remove. 

Epichlorhydrin rubbers, whilst being speciality materials, have a useful combination of properties which leads to their use in many applications such as gaskets, oil-field components, fuel pump diaphragms, oil seals, fuel and hydraulic hose and printing rollers. 

Syntheses, physical and chemical properties, and technology of production of epichlorhydrin 03MI85. 

Although only cardol in CNSL has bifunctionality, attempts have been made to modify cardanol to the same effect. Thus reaction of (15 1)-cardanol with phenol in the presence of boron trifluoride afforded the 1,8-bis(hydroxyphenyl)pentadecane structure (ref. 261). Reaction then with a molar proportion of epichlorhydrin and polymerisation resulted in final products considered to be superior in properties to and cheaper than those derived from bisphenol A. The corresponding fully saturated cardbisphenol compound has been converted to a water soluble bis Mannich base by reaction with diethanolamine and formaldehyde (ref. 262) of value for cathodic electrodeposition. In another case of a related bis diethanolamine product, it was found necessary to react the hydroxyl groups with the monoisocyanate resulting from treatment of tolylenediisocyanate (TDI) with a molecular proportion of cardanol (ref. 263) in order to obtain a suitable binder for... 

For the less critical applications, standard (epichlorhydrin/bisphenol A) epoxy resins retain their physical properties well, but are particularly subject to the adverse effects of UV radiation on their appearance. This causes rapid yellowing and chalking due to their aromatic structure and UV agents are ineffective. Therefore, aU mouldings made with these resins which are to be subjected to extended outdoor exposure will benefit from protection by surface coating or shading. 

The most widely used epoxy resins are reaction products of either bisphenol A or a novolac phenolic resin with epichlorhydrin. When used to manufacture corrosion-resistant structures for use in the chemical process industry, epoxy resins are generally hardened with either aromatic or cycloaliphatic amines. The hardeners for epoxy resins are, with few exceptions, added at levels varying from 20phr (parts per hundred resin) to lOOphr. This means that the hardener is actually quite a high proportion of the matrix resin and has quite a profound effect on the mechanical and corrosion properties of the cured resin. Thus the selection of the most suitable hardener is critical to the eventual success of the application. Epoxy resins have viscosities of several thousand mPas at room temperature, which makes it much more difficult to wet out glass fibre efficiently with them than with polyesters. Wet-out therefore involves heating the resin formulation to between 40°C and 60°C to reduce the viscosity to less than 1000 mPas. 

Table 13.3 Typical properties of selected epoxy resins based on bisphenol-A and epichlorhydrin...

Table 13.5 Properties of Ciba o-cresolformaldehyde novalac/epichlorhydrin resins ...

The three most often used epoxy resins for monolithic surfacings are the bisphe-nol A, bisphenol F (epoxy novolac), and epoxy phenol novolac. These base components are reacted with epichlorhydrin to form resins of varying viscosity and molecular weight. The hardening system employed to effect the cure or solidification will determine the following properties of the cured system ... 

Epichlorhydrin-Propylene oxide-allyl glycidyl ether terpolymers These materials were prepared (Hsieh and Wright, 1972) in attempts to combine the very good low temperature properties of PO rubber with the oil resistance of the polyepichlorhydrins. A terpolymer of these monomers in proportion 70 24 6 was claimed to exhibit a good combination of properties and could be vulcanized with conventional sulphur systems. 

Note that epichlorhydrin (ECO) has good low-temperature properties in the co-polymer (C) form, but not in the homopolymer (H) form. Unfortunately it is the H form which gives very low gas permeability." ... 

As in the case of the polymers prepared from reactive oligomers (precursors), the properties of polyepoxides are closely related to the nature of the monomer used for the preparation of this precursor. In the case of epoxy resins, the potential monomers are numerous but, in reality, one of them corresponds to more than 80% of the market it is bisphenol A [or (4,4 -diphenylol)-2-propane], whose reaction with epichlorhydrin was described in Section 7.4.4. This reaction leads to a precursor that is bivalent under the usual conditions of use. The cross-linking of the system imposes the use of a hardener of valence n > 3, and the network formation can then be schematized as follows (here a tetravalent hardener reacts through its reactive hydrogen atoms) ... 

The reaction with amine derivatives such as 4-hydroxybenzeneamine 20 and 4,4 -methylenebis-benzeneamine 22 is used to produce the tri- and telrafunctional epoxies N,N,0-tris(2,3-epoxypropyl)-4-hydroxybenzeneamine 21 and A,A,iV, iV -telrakis (2,3-epoxypropyl)-4,4 -methylenebisbenzeneamine 23, respectively. However, the polyfunctional epoxies that combine the most attractive properties for electronic applications are the resins produced by epoxi-dation of the phenol novolac 24 and cresol novolac 26. Novolac resins are obtained by the condensation of a phenol with formaldehyde in the presence of acid catalysts in such conditions that the degree of polycondensation is in the range of 3—5. The epoxy novolacs 25 and 26 are produced by the reaction of epichlorhydrin with the corresponding phenol novolac and ortho-cresol novolac resins. Epoxy resins are generally characterized by their dynamic viscosity (77) at 25 °C, expressed in millipascal second (mPa s). 

Kartha, K., Srivastava, H. Reaction of epichlorhydrin with carbohydrate polymers. Part II. Starch reaction mechanism and physicochemical properties of modified starch. Starch-Starke 37(9), 297-306 (1985)... 

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