Abstract: An adhesive composition comprising100 parts by weight of a block copolymer (a) containing of at least one polymer block composed mainly ofa vinyl aromatic hydrocarbon and at least one polymer block composed mainly of butadiene in which(i) the vinyl aromatic hydrocarbon content [S] is 10 to 30% by weight,(ii) the 1,2-vinyl content of butadiene portion [V] is 20 to 50%, and(iii) the relationship between said vinyl aromatic hydrocarbon content [S] and said 1,2-vinyl content of butadiene portion [V] satisfies the formula,:40.ltoreq.[S]+[V].ltoreq.7040 to 200 parts by weight of a tackifier (b), and, optionallyvarious stabilizers, and a process for producing said composition.

Abstract: A random SBR having excellent tensile strength, resilience, and abrasion resistance as well as a reduced heat buildup property, which comprises 10% to 40% by weight of styrene units and the balance of butadiene units and has a Mooney viscosity of 30 to 150; a content of butadiene units having 1,2-vinyl structure of 60% or less; a ratio Mw/Mn of from 1.2 to 3.5; and a content of isolated styrene units of 40% or more and a content of another styrene units in long chain block form of 5% or less, both contents being determined by decomposing the copolymer with ozone and by applying a gel permeation chromatographic analysis to the ozone decomposition product.

Abstract: Conjugated diene polymers and copolymers having a high ratio of a trans-1,4 structure content to a cis-1,4 structure content in the diene moiety can be advantageously solution polymerized by using a novel catalyst complex consisting essentially of the following components (a) and (b) or (a), (b), and (c): (a) an organosodium compound, metallic sodium or a sodium amide compound, or a mixture of at least one thereof with an organic compound of sodium other than the sodium amide compound; (b) an organic or organometallic compound of barium, strontium, or calcium; (c) an organometallic compound of an electron deficient metal selected from lithium, beryllium, magnesium, zinc, cadmium, boron, aluminum, gallium, or indium.

Abstract: A process for producing polymers of a conjugated diene, copolymers of a conjugated diene and another conjugated diene, or copolymers of conjugated diene and a vinyl aromatic hydrocarbon, which comprises polymerizing the corresponding monomers in the presence of a complex initiator consisting of components (a) and (b) described below, or (a) and (b) together with one or more components selected from components (c) and (d);(a) An organic compound of barium, strontium or calcium;(b) An organolithium-beryllium compound or an organolithiummagnesium compound;(c) An organolithium compound, an organoberyllium compound or an organomagnesium compound; and(d) An organoaluminum compound or an organozinc compound.The polymers of a conjugated diene containing relatively high trans-1,4 linkage, or the copolymers of a conjugated diene and a vinyl aromatic compound highly randomized and having high bound styrene and high trans-1,4 linkage can be produced at good yields.

Abstract: An isoprene-butadiene copolymer rubber having improved processing properties which comprises a microstructure of the butadiene portion having from 70% to 90% of trans-1,4 linkage and from 2% to 8% of vinyl linkage, an isoprene content of from 3 to 25 wt %, and a styrene content of from 0 to 30 wt %, said copolymer rubber having a Mooney Viscosity of from 30 to 150, and a molecular weight distribution, Mw/Mn of from 1.2 to 3.5, said rubber, in the unelongated state, not showing a melting point measured by the differential calorimeter analysis method. The copolymer rubber of the present invention can be used for tires, for example, a tread and a carcass or for other rubber uses.

Abstract: A tape cassette lid opening device for a magnetic recording tape driving apparatus provided with a tape cassette loading section for receiving a tape cassette and a capstan projecting from the bottom surface of said tape cassette loading section, comprises a tape cassette lid and a tape cassette lid opening mechanism. The tape cassette lid is pivotally mounted on the magnetic recording tape driving apparatus and is pivotable between a first position, in which the tape cassette lid covers the tape cassette loading section, and a second position, in which the tape cassette lid permits the loading of said tape cassette into the tape cassette loading section and unloading of the tape cassette from the tape cassette loading section. The tape cassette lid opening mechanism includes a motor which causes the pivotal motion of the tape cassette lid from said first position to said second position by means of the driving force of the motor.