Multiple Methods for Preparing Epoxy Resin Prepregs
The epoxy matrix resin prepreg consists of epoxy matrix resin and fiber woven fabric, with a controlled volatile content of less than 1%. The mass content of epoxy matrix resin ranges from 37% to 43%. The epoxy matrix resin is composed of 40 parts phenolic epoxy resin, 60 parts bisphenol A epoxy resin, 2-10 parts core-shell polymer, 15-24 parts curing agent, and 3.0-6.0 parts curing accelerator by mass. The curing agent is a complex of dicyandiamide and 4,4'-diaminodiphenyl sulfone, with mass fractions of 4,4'-diaminodiphenyl sulfone and dicyandiamide being 18 and 6, 14 and 7, 10 and 8, or 6 and 9, respectively. The curing accelerator is an organic urea or its derivative.
The prepreg preparation method involves the following steps:
1. Preparation of Epoxy Matrix Resin: a. Weigh 40 parts phenolic epoxy resin, 60 parts bisphenol A epoxy resin, 2-10 parts core-shell polymer, 15-24 parts curing agent, and 3.0-6.0 parts curing accelerator. Heat the mixture to 150°C, stirring continuously. Add the 4,4'-diaminodiphenyl sulfone curing agent, stir, and heat to 150°C for 3-5 minutes, then cool to room temperature to obtain B-order resin. b. Take 30 parts of the B-order resin and place it in a three-roller grinder. Add the dicyandiamide curing agent and 3.0-6.0 parts of the curing accelerator. Grind the resin in the three-roller grinder 3-6 times. Add the remaining B-order resin and grind again 3-6 times to obtain the epoxy matrix resin. Maintain the three-roller grinder temperature at 60-70°C.
2. Preparation of Prepreg: a. Hang single-sided release paper on roller shafts 1, 5, and 4, and double-sided release paper on roller shafts 2, 5, and 3. Form a transmission connection between roller shafts 1, 5, and 4, and between roller shafts 2, 5, and 3. Place fiber woven fabric between single-sided and double-sided release paper. Preheat roller shafts 1 and 2 to 75-85°C. b. Pour the epoxy matrix resin into the "V-shaped" space formed by roller shafts 1 and the fiber woven cloth. Activate the device to allow the fiber woven cloth and epoxy matrix resin to pass through the gap between roller shafts 1 and 2, obtaining prepregs with single-sided and double-sided release paper adhered on both sides. Control the distance force between roller shafts 1 and 2 by 0.1-2mm. The linear speed of roller shaft 2 is 100-300m/h, and the resin temperature is 75-85°C. c. Under the action of roller shaft 4, peel off the single-sided release paper. Simultaneously, roller shaft 3 rolls the prepreg with double-sided release paper adhered to one side, completing the prepreg preparation.