Is copying an educational CD for personal use considered an infringement of intellectual property rights, given that we participated in purchasing it?

If the owners of the cylinder do not specify a prohibition against copying, then there is no harm in copying it so that each of you has a copy. However, if they explicitly prohibit it altogether, then copying is not permissible, even for personal use, and you must seek their permission. Sheikh Ibn Uthaymeen mentioned that custom is followed in this regard, and that copying is not permissible if the owner explicitly prohibits it altogether.