Patent GB-779092-A (GB)
Title: Improvements in or relating to the preparation of epoxy resins from aldehyde-ketone condensation products
IPC: D06M15/39
Filed: 1954-11-11
Abstract: Epoxy resins are prepared by dehydrohalogenating the product obtained by reacting, in presence of a condensation catalyst, (1) an alkane with a 1,2-epoxy or a halohydrin group attached directly to a halogen-bearing carbon atom, and (2) a heterocyclic condensation product of at least 1 mol. of an aldehyde for each active hydrogen atom on the carbon atoms directly attached to the carbonyl group of a ketone.  Suitable reactants designated (1) above are epichlorhydrin, epibromhydrin, 1,4-dichloro-2,3 - epoxybutane, 1 - chloro - 2,3 - epoxypentane, 1,3 - dichloro - 2 - hydroxypropane, 2,4-dibromo-3-hydroxypentane and 2,4-dichloro-3-hydroxybutane.  Th preferred aldehyde is formaldehyde and preferred ketones are acetone, methyl ethyl ketone, cyclohexanone, cyclopentanone, methyl isobutyl ketone, methyl octyl ketone, mesityl oxide and acetoxyacetone.  The epoxy resin forming reaction is preferably performed with a condensation catalyst, e.g. sodium hydroxide or carbonate when using a dihalo-hydroxy-alkane or zinc, ferric or stannic chloride, boron trifluoride-ether complexes, hydrofluoric, sulphuric or phosphoric acid, sodium or potassium hydroxide, sodium acetate or antimony pentachloride when using an epoxy-halo-alkane.  Condensation is preferably effected in a solvent, e.g. cyclohexane, benzene, or tetrahydrofuran at temperatures between 25 DEG  C. and 150 DEG  C. Dehydrohalogenation is effected with alkali, e.g. sodium or potassium hydroxide, carbonate or bicarbonate, borax, oxides or hydroxides of magnesium, zinc, lead, iron or aluminium, or aluminates, silicates or zincates of alkali metals.  The latter are preferably used in organic media, e.g. carbon tetrachloride, 1,3-dioxalane, or dichlorethyl ether.  The products are useful as stabilizing agents for halogen-containing polymers, for modifying other epoxides or as addition to coating or lubricating compositions.  They may be cured with known epoxide curing agents such as amines, e.g. triethylamine, ethylene diamine, amine- or amide-aldehyde resins, diisocyanates, dialdehydes or polycarboxylic acids, and used for castings, coatings or moulded articles.  They are particularly valuable for crease- and shrinkproofing of textile fabrics (see Group IV (c)).  Examples describe the production of epoxy resins, (I) by reacting epichlorhydrin in presence of a boron trifluoride-ether catalyst with an acetone-formaldehyde condensate of formula <FORM:0779092/IV(a)/1> and dehydrohalogenating the products with sodium orthosilicate in dioxane.  A solution of the product in isopropyl alcohol may be cured with citric acid in cotton gingham or rayon.  Alternatively, the polyepoxide may be mixed with a product from bis-phenol and epichlorhydrin and the mixture cured by heating with 2,4,6 - tri - (dimethylaminomethyl) phenol to form a casting.  (II) by similarly reacting epichlorhydrin with a methyl ethyl ketoneformaldehyde condensate of formula <FORM:0779092/IV(a)/2> or by reacting this condensate with 1,3-dichloro-2-hydroxypropane in presence of alkali and dehydrohalogenating the product.  The product mixed with water, methylcellulose, a copolymer of vinylmethyl ether and maleic anhydride, a polyglycol fatty acid ester and zinc fluoroborate is used to treat cotton cloth.  (III) by reacting epichlorhydrin in presence of tetrahydrofuran and a boron trifluoride-ether catalyst with a merityl oxide-formaldehyde condensate (mol. ratio 1 : 7) and dehydrohalogenating the product with sodium orthosilicate in dioxane. The product was used in a textile impregnating composition similar to that of Example (II), but with magnesium fluoborate as the curing catalyst. Specifications 679,536 and 766,273 are referred to.ALSO:Heterocyclic aldehyde-ketone condensates which on reaction with an epoxy-halo-alkene or a di-halo-alkane followed by dehydrohalogenation yield epoxy resins (see Group IV (a)) are prepared from at least one mol. of lower aliphatic aldehyde, preferably formaldehyde, for each active hydrogen on the carbon atoms directly attached to the carbonyl group of the ketone. Preferably, condensation is aided by an alkaline catalyst.  In examples, 1 mol. of acetone is condensed with 8 mols. of formaldehyde (as 37 per cent solution) in presence of calcium oxide at a temperature below 50 DEG C. for 2 hours.  The mixture was filtered, the filtrate acidified, stripped under vacuum, dehydrated by azeotropic distillation with methanol and benzene, filtered and recovered by distillation.  The product had the formula <FORM:0779092/IV(b)/1> A similar product was similarly obtained from 1 mol. of methyl ethyl ketone and 7 mols. of formaldehyde.  It had the formula <FORM:0779092/IV(b)/2> The preparation of a condensate from 1 mol. of mesityl oxide and about 7 mols. of formaldehyde is also described.  Specifications 679,536, [Group IV (a)], and 766,273 are referred to.ALSO:Textile material is crease- and shrink-proofed by impregnation with an aqueous solution or emulsion of an epoxy resin prepared from a heterocyclic ketone-aldehyde condensate and a compound containing or capable of giving rise to epoxy groups (see Group IV(a)), together with a curing agent, followed by heating.  When an emulsion is used, the emulsifying agents are preferably free from nitrogen and strongly acid groups.  In a modification the curing agent for the resin may be applied by spraying to the fabric impregnated with resin.  A list of suitable curing agents is given, the preferred agents being those described in Specification 766,273 [Group IV(a)].  The resins may be applied by dipping or by padding rollers.  One surface only may be treated. The materials may also be applied locally.  In Example 1, a polyepoxide from an acetone-formaldehyde condensate and epichlorhydrin dissolved in aqueous isopropyl alcohol, with nitric acid as curing agent, is applied to cotton gingham and to rayon. Physical properties of the treated fabrics are quoted.  In Example 2, the epoxy resin is prepared from methyl ethyl ketone and formaldehyde and is dispersed in water with the aid of methyl cellulose, a copolymer of vinyl methyl ether and maleic anhydride, and a polyglycol fatty acid ester.  Zinc fluoborate is added as curing catalyst and the emulsion is used to treat cotton print cloth. Example 3 is similar, using an epoxy resin from a mesityl oxide-formaldehyde condensate.  Specification 679,536 also is referred to.