Abstract: The present invention provides a method for producing a polybenzoxazole precursor having reduced contents of residual aprotic polar solvent and residual halogen without discharging a large amount of waste water during purification. The present invention specifically relates to a method for producing a polybenzoxazole precursor, which comprises synthesizing a polybenzoxazole precursor in an aprotic polar solvent, adding and mixing water and a water-insoluble solvent with the resulting polybenzoxazole precursor solution to still stand the solution, and then separating a water layer from the solution to reduce a content of impurities remaining in the polybenzoxazole precursor.

Abstract: The present invention provides a method for producing a polybenzoxazole precursor having reduced contents of residual aprotic polar solvent and residual halogen without discharging a large amount of waste water during purification. The present invention specifically relates to a method for producing a polybenzoxazole precursor, which comprises synthesizing a polybenzoxazole precursor in an aprotic polar solvent, adding and mixing water and a water-insoluble solvent with the resulting polybenzoxazole precursor solution to still stand the solution, and then separating a water layer from the solution to reduce a content of impurities remaining in the polybenzoxazole precursor.

Abstract: A norbornane lactone (meth)acrylate represented by the following general formula (1): where R1 denotes an alkylene group having 2 to 4 carbon atoms, n denotes an integer of 1 to 3, and R2 denotes a hydrogen atom or methyl group.

Abstract: [Object] It is object to provide (meth)acrylate which is liquid state in ordinary temperature and is easy to handle and (meth)acrylate (co)polymer which is improved in solubility to solvent. [Means to Solve Problem] Norbornane lactone (meth)acrylate represented by the following general formula (1): (wherein R1, represents C2-4 alkylene group; n is an integer of 1 to 3; and R2 represents hydrogen atom or methyl group. (Co)polymer obtained by polymerizing a monomer mixture comprising a norbornane lactone (meth) acrylate represented by the general formula (1). Copolymer which is obtained by polymerizing a monomer mixture comprising at least one compound represented by the general formula (1) and at least one compound copolymerizable therewith and which has a weight-average molecular weight (Mw) of 2000 to 200000.