Rare-earth permanent magnet and method for manufacturing rare-earth permanent magnet

A manufacturing method of a rare-earth permanent magnet comprising steps of:

• milling magnet material into magnet powder:
• preparing a mixture by mixing the magnet powder and any one of three kinds of binders
• a binder made of a long-chain hydrocarbon
• or
• a binder made of a polymer or a copolymer consisting of one or more kinds of monomers selectable from possible monomers expressed with a general formula (2)
• (R1 and R2 represent a hydrogen atom, a lower alkyl group, a phenyl group or a vinyl group)
• or
• a binder obtained by mixing the long-chain hydrocarbon and either the polymer or the copolymer;
• obtaining a green sheet by forming the mixture into a sheet-like shape, the mixture is formed by employing a hot melt coating in which the mixture is heated to melt, and turns into a fluid state and then is spread;
• removing the binder by holding the green sheet for a predetermined length of time at binder decomposition temperature in a non-oxidizing atmosphere so that a residual carbon content contained in the permanent magnet after sintering is 1500 ppm or less and a residual oxygen content contained in the permanent magnet after sintering is 2000 ppm or less;
• and
• sintering the green sheet from which the binder has been removed by raising temperature up to sintering temperature.