Solvent-free benzoxazine impregnating varnish and preparation method thereof

The invention relates to solvent-free benzoxazine impregnating varnish and a preparation method thereof. The solvent-free benzoxazine impregnating varnish comprises the following raw materials: 100 parts of benzoxazine resin with the heat resistance index higher than or equal to 175 DEG C, 12-45 parts of epoxy acrylate, 2-20 parts of aldehyde group-containing benzoxazine, 40-70 parts of reactive diluent, 0.5-1 part of initiator and 0.5-1 part of polymerization inhibitor. The solvent-free benzoxazine impregnating varnish compounds the benzoxazine resin and the epoxy acrylate for use, and with the benzoxazine resin as a main component and the aldehyde group-containing benzoxazine as a catalyst, has the advantages of low curing temperature, long storage life, high heat resistance and flame retardance, low cost, environment friendliness and the like, and is applicable for insulating a low-voltage motor.