| 摘要 |
<p>Epoxy compositions suitable for use as coating, adhesives, potting compounds, castings or laminates consist of epoxy compounds having on the average more than one epoxy group per molecule and, as curing catalyst a hydrazide having the general formula: <FORM:0842867/IV(a)/1> in which R is an organic radical having a valency of 2, 3 or 4, n is 0 or 1, Z is an amino, hydroxyl, or carboxylic/acyl hydrazide group and a is in intiger one less than the valency of R. Suitable epoxy compounds are those produced by reacting epichlorhydrin with polyhydroxy compounds, by epoxidising e.g. with hydrogen peroxide and formic acid, unsaturated compounds e.g. fatty oils or copolymers of butadiene with styrene, acrylonitrile or acrylic acid. The mixture of the epoxy compound and hydrazide has a reasonable shelf life and can be heated and recooled repeatedly without permanent hardening. The rate of cure can be accelerated by addition of activators e.g. lead octoate and zinc-octoate-diethylaminopropylamine. Preferably 3/4 mol. dihydrazide is used per epoxy equivalent of the resin. In examples the following hydrazides are used to cure commercial epoxy resins. (1) sebacic (2) adipyl (e) azelayl (4) adipyl azelayl (5) succinic (6) malonyl (7) oxalyl (8) hexahydro terephthalyl (9) isophthalyl (10) isophthalyl with mica, aluminium silicate and iron oxide as fillers (13) p-aminobenzhydrazide (14) the hydrazide of 2,4-dihydroxy benzoic acid (15) p-hydrozybenzhydrazide (16) 3, 5-diaminobenzhydrazide (17) the dihydrazide of m-benzene-bis oxyacetic acid (18) the trihydrazide of citric acid. In Ex. (19) the epoxy resin was first reacted with sebacic acid and then cured with isophthalyl dihydrazide. In Ex. (20) an epoxy resin was produced from epichlorhydin and the reaction product of p-hydroxybenzoic acid with polyethylene glycol, and then cured with isophthalyl dihydrazide. In Ex. (21) an epoxy resin from cashew nut shell liquid was cured with isophthalyl dihydrazide in the presence of "Benton 34" and diethylaminopropylphthalimide-salicylic acid salt.</p> |
