Abstract: A solid catalyst component for olefin polymerization characterized by being formed from (a) a magnesium compound, (b) titanium tetrachloride, (c) a phthalic diester and a derivative thereof, and either (d1) a hydroxylated hydrocarbon compound (phenol, etc.) represented by a specific formula or (d2) a mercapto-containing hydrocarbon compound (thiophenol, etc.) represented by a specific formula. With a catalyst obtained from this solid catalyst component, an olefin polymer can be obtained in extremely high yield. In particular, a propylene polymer which retains high stereoregularity can be obtained in extremely high yield.

Abstract: Solid catalyst components and catalysts which contain (a) magnesium compound, (b) titanium tetrachloride, and (c) a phthalic acid diester or its derivative are useful in the synthesis of olefin polymers in high yields. Particularly, propylene polymers can be obtain in very high yields while retaining high stereoregularity.

Abstract: A solid catalyst component for olefin polymerization characterized by being formed from (a) a magnesium compound, (b) titanium tetrachloride, (c) a phthalic diester and a derivative thereof, and either (d1) a hydroxylated hydrocarbon compound (phenol, etc.) represented by a specific formula or (d2) a mercapto-containing hydrocarbon compound (thiophenol, etc.) represented by a specific formula. With a catalyst obtained from this solid catalyst component, an olefin polymer can be obtained in extremely high yield.

Abstract: A phthalic acid diester derivative represented by a specific formula and an electron donor used in an olefin polymerization catalyst containing the phthalic acid diester derivative as an effective component. The electron donor can produce polymers with a high stereoregularity at an extremely high polymerization activity and high yield, and exhibit a high response to hydrogen.

Abstract: Solid catalyst components and catalysts which comprise (a) a magnesium compound, (b) titanium tetra chloride, and (c) a phthalic acid diester or its derivative represented by a particular formula, can afford polymers of olefins in very high yield. Particularly, propylene polymers can be obtained in very high yield while retaining high stereoregularity. Moreover, they have high responsiveness to hydrogen.

Abstract: An offset type grindstone having a circular metal substrate provided in a central section thereof with a recess having a hole used to mount the grindstone on a power tool, and a grindstone portion including one layer of either diamond grains or CBN grains and formed in one body so as to extend continuously in the direction of an outer circumference of a front surface of the recess, in which grindstone the concentration of the grains on the grindstone portion is set high in a region of an outer circumferential end section thereof, and low in the other region thereof. This grindstone is superior in lifetime with a very high grinding speed and a high flat grindability attained at once.

Abstract: A phthalic acid diester derivative represented by a specific formula and an electron donor used in an olefin polymerization catalyst containing the phthalic acid diester derivative as an effective component. The electron donor can produce polymers with a high stereoregularity at an extremely high polymerization activity and high yield, and exhibit a high response to hydrogen.

Abstract: An offset type grindstone having a circular metal substrate provided in a central section thereof with a recess having a hole used to mount the grindstone on a power tool, and a grindstone portion including one layer of either diamond grains or cBN grains and formed in one body so as to extend continuously in the direction of an outer circumference of a front surface of the recess, in which grindstone the concentration of the grains on the grindstone portion is set high in a region of an outer circumferential end section thereof, and low in the other region thereof. This grindstone is superior in lifetime with a very high grinding speed and a high flat grindability attained at once.