Abstract: An optical material having a high birefringence and a small absolute value of a photoelastic coefficient is provided by use of a resin composition for an optical material comprising a resin (a) having a positive photoelastic coefficient and a negative inherent birefringence and a resin (b) having a negative photoelastic coefficient and a negative inherent birefringence.

Abstract: The present invention provides a molded article obtained from an aliphatic polyester resin composition comprising 60 to 99.9 parts by weight of at least one aliphatic polyester (A) and 0.1 to 40 parts by weight of at least one elastic polymer (B), provided that the total amount of the components (A) and (B) is 100 parts by weight, wherein the aliphatic polyester component in the molded article has an enthalpy of crystal fusion ?H determined using a differential scanning calorimeter of 5 J/g or more, the molded article has a continuous phase composed of the aliphatic polyester (A) and dispersed phases composed of the elastic polymer (B), and the distance T between the walls of the dispersed phases is less than 5.0 ?m.

Abstract: An optical material having a high birefringence and a small absolute value of a photoelastic coefficient is provided by use of a resin composition for an optical material comprising a resin (a) having a positive photoelastic coefficient and a negative inherent birefringence and a resin (b) having a negative photoelastic coefficient and a negative inherent birefringence.

Abstract: It is an object of the present invention to provide a resin composition that is used as an optical material and has a low change in birefringence with external force, and a molding thereof. According to the present invention, there is provided a resin composition comprising an acrylic resin (a) and an aliphatic polyester resin (b).

Abstract: The present invention provides a molded article obtained from an aliphatic polyester resin composition comprising 60 to 99.9 parts by weight of at least one aliphatic polyester (A) and 0.1 to 40 parts by weight of at least one elastic polymer (B), provided that the total amount of the components (A) and (B) is 100 parts by weight, wherein the aliphatic polyester component in the molded article has an enthalpy of crystal fusion ?H determined using a differential scanning calorimeter of 5 J/g or more, the molded article has a continuous phase composed of the aliphatic polyester (A) and dispersed phases composed of the elastic polymer (B), and the distance T between the walls of the dispersed phases is less than 5.0 ?m.

Abstract: A hydrogenated block copolymer has at least two polymer blocks A each having an aromatic vinyl hydrocarbon compound monomer unit and at least two hydrogenated polymer blocks B each having a hydrogenated butadiene monomer unit. At least 90% of olefinically unsaturated double bonds in the polymer blocks mainly having a butadiene monomer unit before hydrogenation have been hydrogenated. At least one of the locks at the terminal of the hydrogenated block copolymer is the polymer block B. The proportion of the terminal polymer blocks B in the hydrogenated block copolymer is 0.1 wt % to 9.1 wt %. The proportion of the aromatic vinyl hydrocarbon compound in the hydrogenated block copolymer is 25 wt % to 80 wt %. The 1,2-bond content of the polymer blocks having a butadiene monomer unit before hydrogenation averages 60 mol % to 99 mol %. The resulting resin composition improves the balance among the appearance of its molded article, tensile elongation at break and moldability.

Abstract: A hydrogenated block copolymer which comprises at least two polymer blocks A each mainly comprising an aromatic vinyl hydrocarbon compound monomer unit and at least two hydrogenated polymer blocks B each mainly comprising a butadiene monomer unit, at least 90% of the olefinically unsaturated double bonds in said polymer block mainly comprising a butadiene monomer unit before hydrogenation having been hydrogenated, wherein at least one of the block at the terminal of the hydrogenated block copolymer is the polymer block B, wherein the proportion of the terminal polymer blocks B in the hydrogenated block copolymer is at least 0.1 wt % but less than 9.

Abstract: A hydrogenated block copolymer comprising: two polymer blocks A mainly comprising vinylaromatic hydrocarbon compound monomer units; and one hydrogenated polymer block B mainly comprising butadiene monomer units, in which at least 90% of olefinically unsaturated double bonds contained in a polymer block mainly comprising butadiene monomer units before hydrogenation have been hydrogenated, wherein a bonding vinylaromatic hydrocarbon compound content in the hydrogenated block copolymer is higher than 13 wt % but lower than 25 wt %, a 1,2-bond content in the unhydrogenated polymer block mainly comprising butadiene monomer units is higher than 40 mol % but lower than 60 mol %, and the copolymer has a quantity of heat of crystal fusion (&Dgr;H) smaller than 0.05 J/g, an order-disorder transition temperature of 200° C. or higher, and a melt flow rate (MFR) value, as determined in accordance with JIS K7210 under the conditions of a temperature of 230° C. and a load of 2.16 kg, of from not smaller than 0.

Abstract: A hydrogenated block copolymer comprising: at least two polymer blocks A mainly comprising vinylaromatic hydrocarbon compound monomer units; and at least two polymer blocks B mainly comprising hydrogenated conjugated diene compound monomer units, in which at least 90% of the olefinically unsaturated double bonds contained in the unhydrogenated polymer block mainly comprising the conjugated diene compound monomer units is hydrogenated, wherein at least one of the terminal blocks is a polymer block B, the proportion of the terminal polymer block B in the hydrogenated block copolymer being 0.1% by weight or higher and lower than 9.1% by weight, and wherein the content of the vinylaromatic hydrocarbon compound units in the hydrogenated block copolymer is 12% by weight or higher and lower than 25% by weight. Also disclosed are a resin composition containing the hydrogenated block copolymer, and a molded article of the resin composition.