To obtain an anhydrous acid curing agent which can give a varnish having a long life even when a high-melting latent cure accelerator is added by dissolving a cure accelerator having a melting temperature of a specified value or above in a liquid anhydrous acid by heating to form a solution.
A cure accelerator having a melting point of 40°C is used. In the production of a liquid anhydrous acid curing system epoxy impregnating varnish, it can be produced without detriment to the latency and curing properties by previously dissolving the latent cure accelerator in an anhydrous acid under heating and adding the solution to an epoxy resin. In the field where electric machine insulated coils, etc., are produced by using a lowly viscous liquid impregnating varnish, the varnish can show a prolonged pot life and is economically effective and besides can be produced easily. For example, manganese (III) acetylacetonate is dissolved in methylendomethylenetetrahydrophthalic anhydride under heating to obtain a black transparent composition, and this is mixed with a difunctional bisphenol A epoxy resin to obtain a black transparent varinish.
KOYAMA TORU
MARUYAMA SHOICHI
KANO YASUSHI
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