Abstract: A heat stabilized block copolymer composition which comprises a block copolymer comprising a polymer block mainly composed of a monoalkenyl aromatic compound and a polymer block mainly composed of a conjugated diene compound, the content of the monoalkenyl aromatic compound being 5-95% by weight based on the total weight of the block copolymer, and phenolic stabilizers. By adding two or more specific phenolic stabilizers to a block copolymer of a monoalkenyl aromatic compound and a conjugated diene compound, there can be obtained a block copolymer composition which exhibits excellent heat stability even under being heated at high temperatures, is high in the effect of being inhibited from formation of gel-like materials and is excellent in color tone.

Abstract: Disclosed is a rubbery polymer comprising a conjugated diene polymer, and bonded thereto, a lithium-detached residue of a lithium-containing organic polymer used as a catalyst in the production of the conjugated diene polymer, wherein the lithium-containing organic polymer is obtained by reacting an organolithium compound with a first polymerizable material comprising at least one conjugated diene monomer and a second polymerizable material comprising at least one aromatic vinyl compound, which second polymerizable material contains at least one multi-vinyl aromatic compound having at least two vinyl groups, and wherein the lithium-containing organic polymer has a specific narrow molecular weight distribution.

Abstract: A block copolymer composition for modifying asphalt, which comprises a mixture of: (A) a block copolymer comprising: at least two polymer blocks each mainly comprising a monoalkenyl aromatic compound; and at least one polymer block mainly comprising a conjugated diene compound; and (B) a block copolymer comprising: at least one polymer block mainly comprising a monoalkenyl aromatic compound; and at least one copolymer block mainly comprising a conjugated diene compound, and having a molecular weight equivalent to 1/3 to 2/3 of the molecular weight of block copolymer (A), wherein (a) the total bonding alkenyl aromatic compound content in the mixture of block copolymers (A) and (B) is from 10 to 50% by weight, wherein (b) the vinyl bond content in the conjugated diene polymer blocks is not greater than 70% by weight, and wherein the block copolymer composition has: (c) a content of (A) component is from 98 to 20% by weight and a content of (B) component is from 2 to 80% by weight; (d) a melt index value of from

Abstract: A process for producing a high impact polystyrene characterized by polymerizing a conjugated diene (preferably, 1,3-butadiene) by the use of an organolithium-based catalyst containing a polyfunctional organolithium compound (preferably, said organolithium-based cataylst is a mixture of a polyfunctional organolithium compound and a monofunctional organolithium compound at such a mixing ratio that the amount of lithium atom in the polyfunctional organolithium compound is 5% by weight or more based on the total sum of the lithium atoms in the respective compounds), coupling the resulting polymer molecules with a polyfunctional treating agent having at least two (preferably, 2-4 on the average) reactive sites capable of reacting with the active lithium terminal of the polymer, dissolving in styrene the conjugated diene polymer thus obtained, which has substantially a network structure and is substantially soluble in styrene, preferably in a proportion of 2-30% by weight, and then radical-polymerizing the resultin